[
    {
        "anchor": "Nonlinear Transport through Coupled Double Quantum Dot Systems: We investigate sequential tunneling transport through a semiconductor double\nquantum dot structure by combining a simple microscopic quantum confinement\nmodel with a Mott-Hubbard type correlation model. We calculate\nnonperturbatively the evolution of the Coulomb blockade oscillations as a\nfunction of the interdot barrier conductance, obtaining good qualitative\nagreement with the experimental data over the whole tunneling regime from the\nweak-coupling individual dot to the strong-coupling coherent double-dot\nmolecular system.",
        "positive": "Spontaneous Magnetization of Composite Fermions: It is argued that the composite fermion liquid is a promising candidate for\nan observation of the elusive, interaction driven magnetization first proposed\nby Bloch seven decades ago. In analogy to what is theoretically believed to be\nthe case for the idealized electron gas in zero magnetic field, this\nspontaneously broken symmetry phase is predicted to occur prior to a transition\ninto the Wigner crystal."
    },
    {
        "anchor": "Fractional-quantum-Hall edges at filling factor 1-1/m: We consider the edge of a two-dimensional electron system that is in the\nquantum-Hall-effect regime at filling factor 1-1/m with m being an odd integer,\nwhere microscopic theory explaining the occurrence of the quantum Hall effect\nin the bulk predicts the existence of two counterpropagating edge-excitation\nmodes. These two modes are the classical edge-magnetoplasmon mode and a\nslow-moving neutral mode. Assuming the electrons to be confined by a coplanar\nneutralizing background of positive charges, and taking careful account of\nlong-range Coulomb interactions, we determine microscopically the velocity of\nthe neutral mode and the edge width. Our results are intended to guide\nexperimental efforts aimed at verifying the existence of the neutral mode,\nwhich would provide a powerful confirmation of the current microscopic\nunderstanding of quantum-Hall physics at the simplest hierarchical filling\nFactors 1-1/m.",
        "positive": "Multicomponent Quantum Hall Ferromagnetism and Landau Level Crossing in\n  Rhombohedral Trilayer Graphene: Using transport measurements, we investigate multicomponent quantum Hall (QH)\nferromagnetism in dual-gated rhombohedral trilayer graphene (r-TLG), in which\nthe real spin, orbital pseudospin and layer pseudospins of the lowest Landau\nlevel form spontaneous ordering. We observe intermediate quantum Hall plateaus,\nindicating a complete lifting of the degeneracy of the zeroth Landau level (LL)\nin the hole-doped regime. In charge neutral r-TLG, the orbital degeneracy is\nbroken first, and the layer degeneracy is broken last and only the in presence\nof an interlayer potential U. In the phase space of U and filling factor, we\nobserve an intriguing hexagon pattern, which is accounted for by a model based\non crossings between symmetry-broken LLs."
    },
    {
        "anchor": "Transformation of an energy spectrum and wave functions in the crossover\n  from two- to three-dimensional topological insulator in HgTe quantum wells:\n  long and thorny way: A magnetotransport and quantum capacitance of the two-dimensional electron\ngas in HgTe/Cd$_x$Hg$_{1-x}$Te quantum wells of a width ($20.2-46.0$)~nm are\nexperimentally investigated. It is shown that the first energy subband of\nspatial quantization is split due to the spin-orbit interaction and the split\nbranches are single-spin, therewith the splitting strength increases with the\nincrease of the quantum well width. The electron effective masses in the\nbranches are close to each other within the actual density range.\nMagneto-intersubband oscillations (MISO) observed in the structures under study\nexhibit the growing amplitude with the increasing electron density that\ncontradicts to the expected decrease of wave function overlap for the\nrectangular quantum well. To interpret the data obtained, we have used a\nself-consistent approach to calculate the electron energy spectrum and the wave\nfunction within framework of the \\emph{kP}-model. It has been in particular\nshown that the MISO amplitude increase results from the increasing overlap of\nthe wave functions due to their shift from the gate electrode with the gate\nvoltage increase known as phenomenon of the negative electron polarizability.\nThe results obtained from the transport experiments are supported by quantum\ncapacitance measurements.",
        "positive": "One-dimensional Quantum Wire Formed at the Boundary Between Two\n  Insulating LaAlO3/SrTiO3 Interfaces: We grow a tiled structure of insulating two dimensional LaAlO3/SrTiO3\ninterfaces composed of alternating one and three LaAlO3 unit cells. The\nboundary between two tiles is conducting. At low temperatures this conductance\nexhibits quantized steps as a function of gate voltage indicative of a one\ndimensional channel. The step size of half the quantum of conductance is an\nevidence for absence of spin degeneracy."
    },
    {
        "anchor": "Hot-Carrier Seebeck Effect: Diffusion and Remote Detection of Hot\n  Carriers in Graphene: We investigate hot carrier propagation across graphene using an electrical\nnonlocal injection/detection method. The device consists of a monolayer\ngraphene flake contacted by multiple metal leads. Using two remote leads for\nelectrical heating, we generate a carrier temperature gradient that results in\na measurable thermoelectric voltage VNL across the remaining (detector) leads.\nDue to the nonlocal character of the measurement, VNL is exclusively due to the\nSeebeck effect. Remarkably, a departure from the ordinary relationship between\nJoule power P and VNL, VNL ~ P, becomes readily apparent at low temperatures,\nrepresenting a fingerprint of hot-carrier dominated thermoelectricity. By\nstudying VNL as a function of bias, we directly determine the carrier\ntemperature and the characteristic cooling length for hot-carrier propagation,\nwhich are key parameters for a variety of new applications that rely on\nhot-carrier transport.",
        "positive": "Tunable Magnetic Textures: From Majorana Bound States to Braiding: A versatile control of magnetic systems, widely used to store information,\ncan also enable manipulating Majorana bounds states (MBS) and implementing\nfault-tolerant quantum information processing. The proposed platform relies on\nthe proximity-induced superconductivity in a two-dimensional electron gas\nplaced next to an array of magnetic tunnel junctions (MTJs). A change in the\nmagnetization configuration in the MTJ array creates tunable magnetic textures\nthereby removing several typical requirements for MBS: strong spin-orbit\ncoupling, applied magnetic field, and confinement by one-dimensional structures\nwhich complicates demonstrating non-Abelian statistics through braiding. Recent\nadvances in fabricating two-dimensional epitaxial superconductor/semiconductor\nheterostructures and designing tunable magnetic textures support the\nfeasibility of this novel platform for MBS."
    },
    {
        "anchor": "Energy-Momentum dispersion relation of plasmarons in bilayer graphene: The relation between the energy and momentum of plasmarons in bilayer\ngraphene is investigated within the Overhauser approach, where the\nelectron-plasmon interaction is described as a field theoretical problem. We\nfind that the Dirac-like spectrum is shifted by $\\Delta E(\\mathbf{k})\\sim\n100\\div150\\,{\\rm meV}$ depending on the electron concentration $n_{e}$ and\nelectron momentum. The shift increases with electron concentration as the\nenergy of plasmons becomes larger. The dispersion of plasmarons is more\npronounced than in the case of single layer graphene, which is explained by the\nfact that the energy dispersion of electrons is quadratic and not linear. We\nexpect that these predictions can be verified using angle-resolved\nphotoemission spectroscopy (ARPES).",
        "positive": "Electrical control of near-field energy transfer between quantum dots\n  and 2D semiconductors: We investigate near-field energy transfer between chemically synthesized\nquantum dots (QDs) and two-dimensional semiconductors. We fabricate devices in\nwhich electrostatically gated semiconducting monolayer molybdenum disulfide\n(MoS2) is placed atop a homogenous self-assembled layer of core-shell CdSSe\nQDs. We demonstrate efficient non-radiative F\\\"orster resonant energy transfer\n(FRET) from QDs into MoS2 and prove that modest gate-induced variation in the\nexcitonic absorption of MoS2 lead to large (~500%) changes in the FRET rate.\nThis, in turn, allows for up to ~75% electrical modulation of QD\nphotoluminescence intensity. The hybrid QD/MoS2 devices operate within a small\nvoltage range, allow for continuous modification of the QD photoluminescence\nintensity, and can be used for selective tuning of QDs emitting in the\nvisible-IR range."
    },
    {
        "anchor": "Forster mechanism of electron-driven proton pump: We examine a simple model of proton pumping through the inner membrane of\nmitochondria in the living cell. We demonstrate that the pumping process can be\ndescribed using approaches of condensed matter physics. In the framework of\nthis model, we show that the resonant F\\\"orster-type energy exchange due to\nelectron-proton Coulomb interaction can provide an unidirectional flow of\nprotons against an electrochemical proton gradient, thereby accomplishing\nproton pumping. The dependence of this effect on temperature as well as\nelectron and proton voltage build-ups are obtained taking into account\nelectrostatic forces and noise in the environment. We find that the proton pump\nworks with maximum efficiency in the range of temperatures and transmembrane\nelectrochemical potentials which correspond to the parameters of living cells.",
        "positive": "Spectroscopic signatures of tetralayer graphene polytypes: Tetralayer graphene has recently become a new addition to the family of\nfew-layer graphene with versatile electronic properties. This material can be\nrealised in three distinctive stacking configurations, for which we determine\nspectroscopic signatures in angle-resolved photoemission spectroscopy (ARPES),\ndynamical optical conductivity, and Raman spectra of inter-band excitations.\nThe reported library of spectral features of tetralayer graphenes can be used\nfor the non-invasive identification of the stacking order realised in a\nparticular film."
    },
    {
        "anchor": "Breakdown electron-hole symmetry in graphene structure with a\n  semiconductor gate: The electron-hole symmetry in the structure \"graphene - insulating substrate\n-semiconductor gate\" is violated due to an asymmetrical drop of potential in\nthe semiconductor gate under positive or negative biases. The gate voltage\ndependencies of concentration and conductivity are calculated for the case of\nSiO_2 substrate placed over low- (moderate-) doped p-Si. Similar dependencies\nof the optical conductivity are analyzed for the case of high-kappa substrates\n(AlN, Al_2O_3, HfO_2, and ZrO_2). The comparison of our results with\nexperimental data shows a good agreement for both cases.",
        "positive": "Doping Mechanisms in Graphene-MoS2 Hybrids: We present a joint theoretical and experimental investigation of charge\ndoping and electronic potential landscapes in hybrid structures composed of\ngraphene and semiconducting single layer MoS2. From first-principles\nsimulations we find electron doping of graphene due to the presence of rhenium\nimpurities in MoS2. Furthermore, we show that MoS2 edges give rise to charge\nreordering and a potential shift in graphene, which can be controlled through\nexternal gate voltages. The interplay of edge and impurity effects allows the\nuse of the graphene-MoS2 hybrid as a photodetector. Spatially resolved\nphotocurrent signals can be used to resolve potential gradients and local\ndoping levels in the sample."
    },
    {
        "anchor": "Topological insulator in junction with ferromagnets: quantum Hall\n  effects: The ferromagnet-topological insulator-ferromagnet (FM-TI-FM) junction\nexhibits thermal and electrical quantum Hall effects. The generated Hall\nvoltage and transverse temperature gradient can be controlled by the directions\nof magnetizations in the FM leads, which inspires the use of FM-TI-FM junctions\nas electrical and as heat switches in spintronic devices. Thermal and\nelectrical Hall coefficients are calculated as functions of the magnetization\ndirections in ferromagnets and the spin-relaxation time in TI. Both the Hall\nvoltage and the transverse temperature gradient decrease but are not completely\nsuppressed even at very short spin-relaxation times. The Hall coefficients turn\nout to be independent of the spin-relaxation time for symmetric configuration\nof FM leads.",
        "positive": "Gap closing and universal phase diagrams in topological insulators: We study a general problem how the gap in a nonmagnetic band insulator closes\nby tuning a parameter. We review our recent results on the classification of\nall the possible gap closing in two and three dimensions. We show that they\naccompany the change of Z_2 topological numbers, and that the gap closings\ncorrespond to phase transitions between the quantum spin Hall and the insulator\nphases. Interestingly, in inversion-asymmetric three-dimensional systems there\nappears a gapless phase between the quantum spin Hall and insulator phases.\nThis gapless phase is due to a topological nature of gap-closing points in\nthree dimensions, but not in two dimensions."
    },
    {
        "anchor": "Charging of a Single InAs QD with Electrically-Injected Holes using a\n  Lateral Electric Field: InAs/GaAs quantum dots (QDs) and quantum dot molecules (QDMs) are\nself-assembled semiconductor nanostructures that can trap a single electron or\nhole with well-defined spin projections. QDs and QDMs have excellent optical\nproperties and have long been of interest for incorporation into quantum\noptoelectronic devices ranging from single photon sources to multi-bit quantum\ncomputers. The properties of single QDs, or carriers confined within those QDs,\ncan be tuned by external electric fields, which provides an important tool for\nthe development of scalable and tunable devices. Deterministic charging of a QD\nwith a single electron or hole is an important tool for quantum devices and is\nwell-established under the application of growth-direction electric fields in a\ndiode structure. Here, we report a new charging mechanism for a single QD in a\n3-electrode device that does not contain a vertical diode and can be used to\ncontrol electric field profiles in two dimensions. We fabricate the device with\nE-beam lithography and characterize photoluminescence from single QDs under\ndifferent bias configurations. Using a combination of experimental data and\nCOMSOL band structure calculations, we explain how the charging originates in\nthe electrical-injection of holes induced by lateral electric fields. We\ndiscuss the applications for this device and the potential for full 2-D\nelectric field control of a single QD and QDM.",
        "positive": "Effect of the spatial reflection symmetry on the distribution of the\n  parametric conductance derivative in ballistic chaotic cavities: We study the effect of left-right symmetry on the distribution of the\nparametric derivative of the dimensionless conductance T with respect to an\nexternal parameter X, dT/dX, of ballistic chaotic cavities with two leads, each\nsupporting N propagating modes. We show that T and dT/dX are uncorrelated for\nany N. For N=1 we calculate the distribution of dT/dX in the presence and\nabsence of time-reversal invariance. In both cases, it has a logarithmic\nsingularity at zero derivative and algebraic tails with an exponent different\nfrom the one of the asymmetric case. We also obtain explicit analytical results\nfor the mean and variance of the distribution of dT/dX for arbitrary N.\nNumerical simulations are performed for N=5 and 10 to show that the\ndistribution P(dT/dX) tends towards a Gaussian one when N increases."
    },
    {
        "anchor": "Tunneling conductance of a metal-semiconductor heterostructure with\n  Rashba effect: We theoretically studied the in-plane tunneling spectroscopy of the hybrid\nstructure composed of a metal and a semiconductor with Rashba spin-orbit\ncoupling. We found that the energy spacing between two distinct features in the\nconductance spectrum can be used to measure the Rashba energy of the\nsemiconductor. We also considered the effect that varying the probability of\nspin-conserving and spin-flip scattering at the interface has on the overall\nconductance. Surprisingly, an increase in interface scattering probability can\nactually result in increased conductance under certain conditions.\nParticularly, in the tunneling regime, an increase in spin-flip scattering\nprobability enhances the conductance. It is also found that the interfacial\nscattering greatly affects the spin polarization of the conductance in metal,\nbut hardly affects that in the semiconductor.",
        "positive": "Photoconductivity calculations of bilayer graphene from first principles\n  and deformation-potential approach: We report first-principles calculations of electron-phonon coupling in\nbilayer graphene and the corresponding contribution to carrier scattering. At\nthe phonon $\\Gamma$ point, electrons with energies less than 200 meV are\nscattered predominantly by LA$^\\prime$ and TA$^\\prime$ modes while\nhigher-energy electron scattering is dominated by optical phonon modes. Based\non a two-temperature model, heat transfer from electrons with an initial\ntemperature of 2000 K to the lattice (phonons) with an initial temperature of\n300 K is computed, and in the overall relaxation process, most of this energy\nscatters into K-point phonon optical modes due to their strong coupling with\nelectrons and their high energies. A Drude model is used to calculate\nphotoconductivity for bilayer graphene with different doping levels. Good\nagreement with prior experimental trends for both the real and imaginary\ncomponents of photoconductivity confirms the model's applicability. The effects\nof doping levels and electron-phonon scattering on photoconductiviy are\nanalyzed. We also extract acoustic and optical deformation potentials from\naverage scattering rates obtained from density functional theory (DFT)\ncalculations and compare associated photoconductivity calculations with DFT\nresults. The comparison indicates that momentum-dependent electron-phonon\nscattering potentials are required to provide accurate predictions."
    },
    {
        "anchor": "Role of magnons and the size effect in heat transport through an\n  insulating ferromagnet/insulator interface: While recent experiments on the spin Seebeck effect have revealed the\ndecisive role of the magnon contribution to the heat current $Q$ in hybrid\nsystems containing thin ferromagnetic layers, the available acoustic mismatch\ntheory does not account for their magnetic properties. Here, we analyze\ntheoretically the heat transfer through an insulating ferromagnet (F)\nsandwiched between two insulators (I). Depending on the relation between the F\nthickness, $d$, and the mean free path of phonons generated by magnons,\n$l_{ls}$, we reveal two qualitatively different regimes in the nonlinear heat\ntransport through the F/I interfaces. Namely, in thick F layers the regime of\nconventional \"Joule\" heating with $Q \\propto T_s^4$ is realized, in which the\ndetailed structure of the F/I interfaces is inessential. Here $T_s$ is the\nmagnon temperature. By contrast, in thin F layers with $d\\ll l_{ls}$, most of\nphonons emitted by magnons can leave F without being absorbed in its interior,\ngiving rise to the \\emph{magnon overheating} regime with $Q \\propto T_s^m$ and\n$m\\gtrsim7$. Conditions for the examination of both regimes and the\ndetermination of $T_s$ from experiments are discussed. The reported results are\nrelevant for the theoretical analysis of the spin Seebeck effect and the\ndevelopment of magnon-based spin caloritronic devices.",
        "positive": "Sensing behavior of acetone vapors on TiO$_2$ nanostructures ---\n  application of density functional theory: The electronic properties of TiO$_2$ nanostructure are explored using density\nfunctional theory. The adsorption properties of acetone on TiO$_2$\nnanostructure are studied in terms of adsorption energy, average energy gap\nvariation and Mulliken charge transfer. The density of states spectrum and the\nband structure clearly reveals the adsorption of acetone on TiO$_2$\nnanostructures. The variation in the energy gap and changes in the density of\ncharge are observed upon adsorption of acetone on n-type TiO$_2$ base material.\nThe results of DOS spectrum reveal that the transfer of electrons takes place\nbetween acetone vapor and TiO$_2$ base material. The findings show that the\nadsorption property of acetone is more favorable on TiO$_2$ nanostructure.\nSuitable adsorption sites of acetone on TiO$_2$ nanostructure are identified at\natomistic level. From the results, it is confirmed that TiO$_2$ nanostructure\ncan be efficiently utilized as a sensing element for the detection of acetone\nvapor in a mixed environment."
    },
    {
        "anchor": "Gate-tunable and high responsivity graphene phototransistors on undoped\n  semiconductor substrates: Due to its high charge carrier mobility, broadband light absorption, and\nultrafast carrier dynamics, graphene is a promising material for the\ndevelopment of high-performance photodetectors. Graphene-based photodetectors\nhave been demonstrated to date using monolayer graphene operating in\nconjunction with either metals or semiconductors. Most graphene devices are\nfabricated on doped Si substrates with SiO2 dielectric used for back gating.\nHere, we demonstrate photodetection in graphene field effect phototransistors\nfabricated on undoped semiconductor (SiC) substrates. The photodetection\nmechanism relies on the high sensitivity of the graphene conductivity to the\nlocal change of the electric field that can result from the photo-excited\ncharge carriers produced in the back-gated semiconductor substrate. We also\nmodeled the device and simulated its operation using the finite element method\nto validate the existence of the field induced photoresponse mechanism and\nstudy its properties. Our graphene phototransistor possesses a room-temperature\nphotoresponsivity as high as ~ 7.4 A/W, higher than the required\nphotoresponsivity (1 A/W) in most practical applications. The light\npower-dependent photocurrent and photoresponsivity can be tuned by the\nsource-drain bias voltage and back-gate voltage. Graphene phototransistors\nbased on this simple and generic architecture can be fabricated by depositing\ngraphene on a variety of undoped substrates, and are attractive for many\napplications in which photodetection or radiation detection is sought.",
        "positive": "Band mixing in the quantum anomalous Hall regime of twisted\n  semiconductor bilayers: Remarkable recent experiments have observed fractional quantum anomalous Hall\n(FQAH) effects at zero field and unusually high temperatures in twisted\nsemiconductor bilayer $t$MoTe$_2$. Intriguing observations in these experiments\nsuch as the absence of integer Hall effects at twist angles where a fractional\nHall effect is observed, do however remain unexplained. The experimental phase\ndiagram as a function of twist angle remains to be established. By\ncomprehensive numerical study, we show that band mixing has large qualitative\nand quantitative effects on the energetics of competing states and their energy\ngaps throughout the twist angle range $\\theta\\leq 4^\\circ$. This lays the\nground for the detailed realistic study of a rich variety of strongly\ncorrelated twisted semiconductor multilayers and an understanding of the phase\ndiagram of these fascinating systems."
    },
    {
        "anchor": "Fractional quantum Hall effect at the filling factor $\u03bd=5/2$: The fractional quantum Hall (FQH) effect at the filling factor $\\nu=5/2$ was\ndiscovered in GaAs heterostructures more than 35 years ago. Various topological\norders have been proposed as possible candidates to describe this FQH state.\nSome of them possess non-Abelian anyon excitations, an entirely new type of\nquasiparticle with fascinating properties. If observed, non-Abelian anyons\ncould offer fundamental building blocks of a topological quantum computer.\nNevertheless, the nature of the FQH state at $\\nu=5/2$ is still under debate.\nIn this chapter, we provide an overview of the theoretical background,\nnumerical results, and experimental measurements pertaining to this special FQH\nstate. Furthermore, we review some recent developments and their possible\ninterpretations. Possible future directions toward resolving the nature of the\n$5/2$ state are also discussed.",
        "positive": "Ultrafast exciton relaxation in monolayer transition metal\n  dichalcogenides: We examine a mechanism by which excitons undergo ultrafast relaxation in\ncommon monolayer transition metal dichalcogenides. It is shown that at\ndensities $\\approx$ 1$\\times$ 10$^{11}$ cm$^{-2}$ and temperatures $ \\le 60$ K,\nexcitons in well known monolayers (MoS$_2$, MoSe$_2$, WS$_2$ and WSe$_2$) exist\nas point-like structureless electron-hole quasi-particles. We evaluate the\naverage rate of exciton energy relaxation due to acoustic phonons via the\ndeformation potential and the piezoelectric coupling mechanisms and examine the\neffect of spreading of the excitonic wavefunction into the region perpendicular\nto the monolayer plane. Our results show that the exciton relaxation rate is\nenhanced with increase in the exciton temperature, while it is decreased with\nincrease in the lattice temperature. Good agreements with available\nexperimental data are obtained when the calculations are extrapolated to room\ntemperatures. A unified approach taking into account the deformation potential\nand piezoelectric coupling mechanisms shows that exciton relaxation induced by\nphonons is as significant as defect assisted scattering and trapping of\nexcitons by surface states in monolayer transition metal dichalcogenides."
    },
    {
        "anchor": "Energy and power fluctuations in ac-driven coherent conductors: Using a scattering matrix approach we study transport in coherent conductors\ndriven by a time-periodic bias voltage. We investigate the role of\nelectron-like and hole-like excitations created by the driving in the energy\ncurrent noise and we reconcile previous studies on charge current noise in this\nkind of systems. The energy noise reveals additional features due to\nelectron-hole correlations. These features should be observable in power\nfluctuations. In particular, we show results for the case of a harmonic and\nbi-harmonic driving and of Lorentzian pulses applied to a two-terminal\nconductor, addressing the recent experiments of Refs. 1 and 2.",
        "positive": "Single-mode heat conduction by photons: Electrical conductance is quantized in units of $\\sigma_{\\rm Q}=2e^2/h$ in\nballistic one-dimensional conductors. Similarly, thermal conductance at\ntemperature $T$ is expected to be limited by the quantum of thermal conductance\nof one mode, $G_{\\rm Q} = \\frac{\\pi k_{\\rm B}^2}{6\\hbar}T$, when physical\ndimensions are small in comparison to characteristic wavelength of the\ncarriers. The relation between $\\sigma_{\\rm Q}$ and $G_{\\rm Q}$ obeys the\nWiedemann-Franz law for ballistic electrons (apart from factor 2 in\n$\\sigma_{\\rm Q}$ due to spin degeneracy), but somewhat amazingly the same\nexpression of $G_{\\rm Q}$ is expected to hold also for phonons and photons, or\nany other particles with arbitrary exclusion statistics. The single-mode heat\nconductance is particularly relevant in nano-structures, e.g., when studying\nheat conduction by phonons in dielectric materials, or cooling of electrons in\nmetals at very low temperatures. Here we show, based on our experimental\nresults, that at low temperatures heat is transferred by photon radiation, in\nour case along a superconducting line, when electron-phonon as well as normal\nelectronic heat conduction are frozen out. Thermal conductance is limited by\n$G_{\\rm Q}$, approaching this value towards low temperatures. Our observation\nhas implications on, e.g., performance and design of ultra-sensitive bolometers\nand electronic micro-refrigerators, whose operation is largely dependent on\nweak thermal coupling between the device and its environment."
    },
    {
        "anchor": "Data-driven Thiele equation approach for solving the full nonlinear\n  spin-torque vortex oscillator dynamics: The dynamics of vortex based spin-torque nano-oscillators is investigated\ntheoretically. Starting from a fully analytical model based on the Thiele\nequation approach, fine-tuned data-driven corrections are carried out to the\ngyrotropic and damping terms. These adjustments, based on micromagnetic\nsimulation results, allow to quantitatively model the response of such\noscillators to any dc current within the range of the vortex stability. Both,\nthe transient and the steady-state regimes are accurately predicted under the\nproposed data-driven Thiele equation approach. Furthermore, the computation\ntime required to solve the dynamics of such system is reduced by about six\norders of magnitude compared to the most powerful micromagnetic simulations.\nThis major breakthrough opens the path for unprecedented high-throughput\nsimulations of spin-torque vortex oscillators submitted to long-duration input\nsignals, for example in neuromorphic computing applications.",
        "positive": "Microwave-frequency scanning gate microscopy of a Si/SiGe double quantum\n  dot: Conventional quantum transport methods can provide quantitative information\non spin, orbital, and valley states in quantum dots, but often lack spatial\nresolution. Scanning tunneling microscopy, on the other hand, provides\nexquisite spatial resolution of the local electronic density of states, but\noften at the expense of speed. Working to combine the spatial resolution and\nenergy sensitivity of scanning probe microscopy with the speed of microwave\nmeasurements, we couple a metallic probe tip to a Si/SiGe double quantum dot\nthat is integrated with a local charge detector. We first demonstrate that a\ndc-biased tip can be used to change the charge occupancy of the double dot. We\nthen apply microwave excitation through the scanning tip to drive\nphoton-assisted tunneling transitions in the double dot. We infer the double\ndot energy level diagram from the frequency and detuning dependence of the\nphoton-assisted tunneling resonance condition. These measurements allow us to\nresolve $\\sim$65 $\\mu$eV excited states, an energy scale consistent with\ntypical valley splittings in Si/SiGe. Future extensions of this approach may\nallow spatial mapping of the valley splitting in Si devices, which is of\nfundamental importance for spin-based quantum processors."
    },
    {
        "anchor": "Shaping electronic flows with strongly correlated physics: Nonequilibrium quantum transport is of central importance in nanotechnology.\nIts description requires the understanding of strong electronic correlations,\nwhich couple atomic-scale phenomena to the nanoscale. So far, research in\ncorrelated transport focused predominantly on few-channel transport, precluding\nthe investigation of cross-scale effects. Recent theoretical advances enable\nthe solution of models that capture the interplay between quantum correlations\nand confinement beyond a few channels. This problem is the focus of this study.\nWe consider an atomic impurity embedded in a metallic nanosheet spanning two\nleads, showing that transport is significantly altered by tuning only the phase\nof a single, local hopping parameter. Furthermore -- depending on this phase --\ncorrelations reshape the electronic flow throughout the sheet, either funneling\nit through the impurity or scattering it away from a much larger region. This\ndemonstrates the potential for quantum correlations to bridge length scales in\nthe design of nanoelectronic devices and sensors.",
        "positive": "Fully guided electrically-controlled exciton polaritons: We demonstrate two types of waveguide structures which optically confine\nexciton- polaritons in two dimensions and act as polaritonic channels. We show\na strong optical confinement in an etched rectangular waveguide, that\nsignificantly increases the propa- gation distance of the polaritons and allow\nto direct them in curved trajectories. Also, we show low-loss optical guiding\nover a record-high of hundreds of microns which is com- bined seamlessly with\nelectrical control of the polaritons, in a strip waveguide formed by\nelectrically conductive and optically transparent strips deposited on top of a\nplanar waveguide. Both structures are scalable and easy to fabricate and offer\nnew possibilities for designing complex polaritonic devices."
    },
    {
        "anchor": "Moire superlattice effects in graphene/boron-nitride van der Waals\n  heterostructures: Van der Waals heterostructures of graphene and hexagonal boron nitride\nfeature a moir\\'e superlattice for graphene's Dirac electrons. Here, we review\nthe effects generated by this superlattice, including a specific miniband\nstructure featuring gaps and secondary Dirac points, and a fractal spectrum of\nmagnetic minibands known as Hofstadter's butterfly.",
        "positive": "Atomistic-to-Continuum Multiscale Modeling with Long-Range Electrostatic\n  Interactions in Ionic Solids: We present a multiscale atomistic-to-continuum method for ionic crystals with\ndefects. Defects often play a central role in ionic and electronic solids, not\nonly to limit reliability, but more importantly to enable the functionalities\nthat make these materials of critical importance. Examples include solid\nelectrolytes that conduct current through the motion of charged point defects,\nand complex oxide ferroelectrics that display multifunctionality through the\nmotion of domain wall defects. Therefore, it is important to understand the\nstructure of defects and their response to electrical and mechanical fields. A\ncentral hurdle, however, is that interactions in ionic solids include both\nshort-range atomic interactions as well as long-range electrostatic\ninteractions. Existing atomistic-to-continuum multi-scale methods, such as the\nQuasicontinuum method, are applicable only when the atomic interactions are\nshort-range. In addition, empirical reductions of quantum mechanics to density\nfunctional models are unable to capture key phenomena of interest in these\nmaterials. To address this open problem, we develop a multiscale atomistic\nmethod to coarse-grain the long-range electrical interactions in ionic crystals\nwith defects. In these settings, the charge density is rapidly varying, but in\nan almost-periodic manner. The key idea is to use the polarization density\nfield as a multiscale mediator that enables efficient coarse-graining by\nexploiting the almost-periodic nature of the variation. In regions far from the\ndefect, where the crystal is close-to-perfect, the polarization field serves as\na proxy that enables us to avoid accounting for the details of the charge\nvariation. We combine this approach for long-range electrostatics with the\nstandard Quasicontinuum method for short-range interactions to achieve an\nefficient multiscale atomistic-to-continuum method."
    },
    {
        "anchor": "Fabry-Perot interference, Kondo effect and Coulomb blockade in carbon\n  nanotubes: High quality single wall carbon nanotube quantum dots have been made showing\nboth metallic and semiconducting behavior. Some of the devices are identified\nas small band gap semiconducting nanotubes with relatively high broad\nconductance oscillations for hole transport through the valence band and low\nconductance Coulomb blockade oscillations for electron transport through the\nconduction band. The transition between these regimes illustrates that\ntransport evolves from being wave-like transmission known as Fabry-Perot\ninterference to single particle-like tunneling of electrons or holes. In the\nintermediate regime four Coulomb blockade peaks appear in each Fabry-Perot\nresonance, which is interpreted as entering the SU(4) Kondo regime. A bias\nshift of opposite polarity for the Kondo resonances for one electron and one\nhole in a shell is in some cases observed.",
        "positive": "Emergent Geometry Fluctuation in Quantum Confined Electron Systems: The intrinsic geometric degree of freedom that was proposed to determine the\noptimal correlation energy of the fractional quantum Hall states, is analyzed\nfor quantum confined planar electron systems. One major advantage in this case\nis that the role of various unimodular metrics resulting from the absence of\nrotational symmetry can be investigated independently or concurrently. For\ninteracting electrons in our system, the confinement metric due to the\nanisotropy shifts the minimum of the ground state and the low-lying excited\nstates from the isotropic case much more strongly than the corresponding shift\ndue to the unimodular Galilean metric. Implications of these results for\npossible observation of higher Landau level filling fractions have been\nelucidated."
    },
    {
        "anchor": "Dry-transferred CVD graphene for inverted spin valve devices: Integrating high-mobility graphene grown by chemical vapor deposition (CVD)\ninto spin transport devices is one of the key tasks in graphene spintronics. We\nuse a van der Waals pickup technique to transfer CVD graphene by hexagonal\nboron nitride (hBN) from the copper growth substrate onto predefined Co/MgO\nelectrodes to build inverted spin valve devices. Two approaches are presented:\n(i) a process where the CVD-graphene/hBN stack is first patterned into a bar\nand then transferred by a second larger hBN crystal onto spin valve electrodes\nand (ii) a direct transfer of a CVD-graphene/hBN stack. We report record high\nspin lifetimes in CVD graphene of up to 1.75 ns at room temperature. Overall,\nthe performances of our devices are comparable to devices fabricated from\nexfoliated graphene also revealing nanosecond spin lifetimes. We expect that\nour dry transfer methods pave the way towards more advanced device geometries\nnot only for spintronic applications but also for CVD-graphene-based\nnanoelectronic devices in general where patterning of the CVD graphene is\nrequired prior to the assembly of final van der Waals heterostructures.",
        "positive": "Oxygen adsorption effect on magnetic properties of graphite: Both experimental and theoretical studies of the magnetic properties of\nmicrographite and nanographite indicate a crucial role of the partial oxidation\nof graphitic zigzag edges in ferromagnetism. In contrast to total and partial\nhydrogenation, the oxidation of half of the carbon atoms on the graphite edges\ntransforms the antiferromagnetic exchange interaction between graphite planes\nand over graphite ribbons to the ferromagnetic interaction. The stability of\nthe ferromagnetism is discussed."
    },
    {
        "anchor": "Topological phases of non-Hermitian systems: Recent experimental advances in controlling dissipation have brought about\nunprecedented flexibility in engineering non-Hermitian Hamiltonians in open\nclassical and quantum systems. A particular interest centers on the topological\nproperties of non-Hermitian systems, which exhibit unique phases with no\nHermitian counterparts. However, no systematic understanding in analogy with\nthe periodic table of topological insulators and superconductors has been\nachieved. In this paper, we develop a coherent framework of topological phases\nof non-Hermitian systems. After elucidating the physical meaning and the\nmathematical definition of non-Hermitian topological phases, we start with\none-dimensional lattices, which exhibit topological phases with no Hermitian\ncounterparts and are found to be characterized by an integer topological\nwinding number even with no symmetry constraint, reminiscent of the quantum\nHall insulator in Hermitian systems. A system with a nonzero winding number,\nwhich is experimentally measurable from the wave-packet dynamics, is shown to\nbe robust against disorder, a phenomenon observed in the Hatano-Nelson model\nwith asymmetric hopping amplitudes. We also unveil a novel bulk-edge\ncorrespondence that features an infinite number of (quasi-)edge modes. We then\napply the K-theory to systematically classify all the non-Hermitian topological\nphases in the Altland-Zirnbauer classes in all dimensions. The obtained\nperiodic table unifies time-reversal and particle-hole symmetries, leading to\nhighly nontrivial predictions such as the absence of non-Hermitian topological\nphases in two dimensions. We provide concrete examples for all the nontrivial\nnon-Hermitian AZ classes in zero and one dimensions. In particular, we identify\na Z2 topological index for arbitrary quantum channels. Our work lays the\ncornerstone for a unified understanding of the role of topology in\nnon-Hermitian systems.",
        "positive": "Unexpected systematic degeneracy in a system of two coupled Gaudin\n  models with homogeneous couplings: We report an unexpected systematic degeneracy between different multiplets in\nan inversion symmetric system of two coupled Gaudin models with homogeneous\ncouplings, as occurring for example in the context of solid state quantum\ninformation processing. We construct the full degenerate subspace (being of\nmacroscopic dimension), which turns out to lie in the kernel of the commutator\nbetween the two Gaudin models and the coupling term. Finally we investigate to\nwhat extend the degeneracy is related to the inversion symmetry of the system\nand find that indeed there is a large class of systems showing the same type of\ndegeneracy."
    },
    {
        "anchor": "Excitons in quantum-ring structures in a magnetic field: Optical\n  properties and persistent currents: We study theoretically the magnetic field effect on a neutral, but\npolarizable exciton confined in quantum-ring structures. For excitons with a\nnonzero dipole moment, a novel magnetic interference effect occurs: The ground\nstate of an exciton confined in a finite-width quantum ring possesses a nonzero\nangular momentum with increasing normal magnetic field. This effect is\naccompanied by a suppression of the photoluminescence in well-defined\nmagnetic-field intervals. The magnetic interference effect is calculated for\ntype-II quantum dots and quantum rings.",
        "positive": "Nanotube heat conductors under tensile strain: Reducing the three-phonon\n  scattering strength of acoustic phonons: Acoustic phonons play a special role in lattice heat transport, and confining\nthese low-energy modes in low-dimensional materials may enable nontrivial\ntransport phenomena. By applying lowest-order anharmonic perturbation theory to\nan atomistic model of a carbon nanotube, we investigate numerically and\nanalytically the spectrum of three-phonon scattering channels in which at least\none phonon is of low energy. Our calculations show that acoustic longitudinal\n(LA), flexural (FA), and twisting (TW) modes in nanotubes exhibit a distinct\ndissipative behavior in the long-wavelength limit, $|k| \\rightarrow 0$, which\nmanifests itself in scattering rates that scale as $\\Gamma_{\\rm{LA}}\\sim\n|k|^{-1/2}$, $\\Gamma_{\\rm{FA}}\\sim k^0$, and $\\Gamma_{\\rm{TW}}\\sim |k|^{1/2}$.\nThese scaling relations are a consequence of the harmonic lattice approximation\nand critically depend on the condition that tubes are free of mechanical\nstrain. In this regard, we show that small amounts of tensile lattice strain\n$\\epsilon$ reduce the strength of anharmonic scattering, resulting in\nstrain-modulated rates that, in the long-wavelength limit, obey $\\Gamma \\sim\n\\epsilon^{r} |k|^{s}$ with $r\\leq 0$ and $s\\geq 1$, irrespectively of acoustic\nmode polarization. Under the single-mode relaxation time approximation of the\nlinearized Peierls-Boltzmann equation (PBE), the long-tube limit of lattice\nthermal conductivity in stress-free and stretched tube configurations can be\nunambiguously characterized. Going beyond relaxation time approximations,\nanalytical results obtained in the present study may help to benchmark\nnumerical routines which aim at deriving the thermal conductivity of nanotubes\nfrom an exact solution of the PBE."
    },
    {
        "anchor": "The Theory of Scanning Quantum Dot Microscopy: Electrostatic forces are among the most common interactions in nature and\nomnipresent at the nanoscale. Scanning probe methods represent a formidable\napproach to study these interactions locally. The lateral resolution of such\nimages is, however, often limited as they are based on measuring the force\n(gradient) due to the entire tip interacting with the entire surface. Recently,\nwe developed scanning quantum dot microscopy (SQDM), a new technique for the\nimaging and quantification of surface potentials which is based on the gating\nof a nanometer-size tip-attached quantum dot by the local surface potential and\nthe detection of charge state changes via non-contact atomic force microscopy.\nHere, we present a rigorous formalism in the framework of which SQDM can be\nunderstood and interpreted quantitatively. In particular, we present a general\ntheory of SQDM based on the classical boundary value problem of electrostatics,\nwhich is applicable to the full range of sample properties (conductive vs\ninsulating, nanostructured vs homogeneously covered). We elaborate the general\ntheory into a formalism suited for the quantitative analysis of images of\nnanostructured but predominantly flat and conductive samples.",
        "positive": "Suspended graphene films and their Casimir interaction with ideal\n  conductor: We adopt the Dirac model for graphene and calculate the Casimir interaction\nenergy between a plane suspended graphene sample and a parallel plane ideal\nconductor. We employ both the Quantum Field Theory (QFT) approach, and the\nLifshitz formula generalizations. The first approach turns out to be the\nleading order in the coupling constant of the second one. The Casimir\ninteraction for this system appears to be rather weak but experimentally\nmeasurable. It exhibits a strong dependence on the mass of the quasi-particles\nin graphene."
    },
    {
        "anchor": "Exchange-biased quantum anomalous Hall effect: The quantum anomalous Hall (QAH) effect is characterized by a dissipationless\nchiral edge state with a quantized Hall resistance at zero magnetic field.\nManipulating the QAH state is of great importance in both the understanding of\ntopological quantum physics and the implementation of dissipationless\nelectronics. Here, we realized the QAH effect in the magnetic topological\ninsulator Cr-doped (Bi,Sb)2Te3 (CBST) grown on an uncompensated\nantiferromagnetic insulator Al-doped Cr2O3. Through polarized neutron\nreflectometry (PNR), we find a strong exchange coupling between CBST and\nAl-Cr2O3 surface spins fixing interfacial magnetic moments perpendicular to the\nfilm plane. The interfacial coupling results in an exchange-biased QAH effect.\nWe further demonstrate that the magnitude and sign of the exchange bias can be\neffectively controlled using a field training process to set the magnetization\nof the Al-Cr2O3 layer. Our work demonstrates the use of the exchange bias\neffect to effectively manipulate the QAH state, opening new possibilities in\nQAH-based spintronics.",
        "positive": "Characterization of a multimode coplanar waveguide parametric amplifier: We characterize a novel Josephson parametric amplifier based on a\nflux-tunable quarter-wavelength resonator. The fundamental resonance frequency\nis ~1GHz, but we use higher modes of the resonator for our measurements. An\non-chip tuning line allows for magnetic flux pumping of the amplifier. We\ninvestigate and compare degenerate parametric amplification, involving a single\nmode, and nondegenerate parametric amplification, using a pair of modes. We\nshow that we reach quantum-limited noise performance in both cases, and we show\nthat the added noise can be less than 0.5 added photons in the case of low\ngain."
    },
    {
        "anchor": "Tuning thermal transport in graphene via combinations of molecular\n  antiresonances: We propose a method to engineer the phonon thermal transport properties of\nlow dimensional systems. The method relies on introducing a predetermined\ncombination of molecular adsorbates, which give rise to antiresonances at\nfrequencies specific to the molecular species. Despite their dissimilar\ntransmission spectra, thermal resistances due to individual molecules remain\nalmost the same for all species. On the other hand, thermal resistance due to\ncombinations of different species are not additive and show large differences\ndepending on the species. Using a toy model, the physics underlying the\nviolation of resistance summation rule is investigated. It is demonstrated that\nequivalent resistance of two scatterers having the same resistances can be\nclose to the sum of the constituents or $\\sim$70\\% of it depending on the\nrelative positions of the antiresonances. The relative positions of the\nantiresonances determine the net change in transmission, therefore the\nequivalent resistance. Since the entire spectrum is involved in phonon spectrum\nchanges in different parts of the spectrum become important. Performing\nextensive first-principles based computations, we show that these distinctive\nattributes of phonon transport can be useful to tailor the thermal transport\nthrough low dimensional materials, especially for thermoelectric and thermal\nmanagement applications.",
        "positive": "Temperature Dependence of Highly Excited Exciton Polaritons in\n  Semiconductor Microcavities: Observations of polariton condensation in semiconductor microcavities suggest\nthat polaritons can be exploited as a novel type of laser with low input-power\nrequirements. The low-excitation regime is approximately equivalent to thermal\nequilibrium, and a higher excitation results in more dominant nonequilibrium\nfeatures. Although standard photon lasing has been experimentally observed in\nthe high excitation regime, e-h pair binding can still remain even in the\nhigh-excitation regime theoretically. Therefore, the photoluminescence with a\ndifferent photon lasing mechanism is predicted to be different from that with a\nstandard photon lasing. In this paper, we report the temperature dependence of\nthe change in photoluminescence with the excitation density. The second\nthreshold behavior transited to the standard photon lasing is not measured at a\nlow-temperature, high-excitation power regime. Our results suggest that there\nmay still be an electron--hole pair at this regime to give a different photon\nlasing mechanism."
    },
    {
        "anchor": "Conductance of a Dissipative Quantum Dot: Nonequilibrium Crossover Near\n  a Non-Fermi-Liquid Quantum Critical Point: We find the nonlinear conductance of a dissipative resonant level in the\nnonequilibrium steady state near its quantum critical point. The system\nconsists of a spin-polarized quantum dot connected to two resistive leads that\nprovide ohmic dissipation. We focus on the crossover from the strong-coupling,\nnon-Fermi-liquid regime to the weak-coupling, Fermi-liquid ground state, a\ncrossover driven by the instability of the quantum critical point to\nhybridization asymmetry or detuning of the level in the dot. We show that the\ncrossover properties are given by tunneling through an effective single barrier\ndescribed by the boundary sine-Gordon model. The nonlinear conductance is then\nobtained from thermodynamic Bethe ansatz results in the literature, which were\ndeveloped to treat tunneling in a Luttinger liquid. The current-voltage\ncharacteristics are thus found for any value of the resistance of the leads.\nFor the special case of lead resistance equal to the quantum resistance, we\nfind mappings onto, first, the two-channel Kondo model and, second, an\neffectively noninteracting model from which the nonlinear conductance is found\nanalytically. A key feature of the general crossover function is that the\nnonequilibrium crossover driven by applied bias is different from the crossover\ndriven by temperature -- we find that the nonequilibrium crossover is\nsubstantially sharper. Finally, we compare to experimental results for both the\nbias and temperature crossovers: the agreement is excellent.",
        "positive": "Tunable quantum interference in bilayer graphene in double-resonant\n  Raman scattering: The line shape of the double-resonant $2D$ Raman mode in bilayer graphene is\noften considered to be characteristic for a certain laser excitation energy.\nHere, in a joint experimental and theoretical study, we analyze the dependence\nof the double-resonant Raman scattering processes in bilayer graphene on the\nelectronic broadening parameter $\\gamma$. We demonstrate that the ratio between\nsymmetric and anti-symmetric scattering processes sensitively depends on the\nlifetime of the electronic states, explaining the experimentally observed\nvariation of the complex $2D$-mode line shape."
    },
    {
        "anchor": "Density of states as a probe of electrostatic confinement in graphene: We theoretically analyze the possibility to confine electrons in single-layer\ngraphene with the help of metallic gates, via the evaluation of the density of\nstates of such a gate-defined quantum dot in the presence of a ring-shaped\nmetallic contact. The possibility to electrostatically confine electrons in a\ngate-defined ``quantum dot'' with finite-carrier density, surrounded by an\nundoped graphene sheet, strongly depends on the integrability of the electron\ndynamics in the quantum dot. With the present calculations we can\nquantitatively compare confinement in dots with integrable and chaotic\ndynamics, and verify the prediction that the Berry phase associated with the\npseudospin leads to partial confinement in situations where no confinement is\nexpected according to the arguments relying on the classical dynamics only.",
        "positive": "Strong Aharonov-Bohm quantum interference in simply-connected\n  LaAlO$_3$/SrTiO$_3$ structures: We report Aharonov-Bohm (AB)-type quantum interference in simply-connected\ndevices created at the LaAlO$_3$/SrTiO$_3$ interface using conductive-atomic\nforce microscope (c-AFM) lithography. The oscillations are multi-periodic\nfunctions of magnetic field strength, and they exhibit a substantial magnetic\nhysteresis with frequencies that depends on the magnetic sweep direction. The\noscillation amplitude for the lowest two frequencies approaches $e^2/h$,\nconsistent with the theoretical maximum for the AB effect, and harmonics up to\nthird order are observable. Broadband quasiperiodic behavior is reported in a\nfraction of simply-connected electron waveguide devices that exhibit magnetic\nasymmetries. Curiously, nanoscale ring devices that are multiply-connected lack\nsignatures of AB quantum interference. The interference phenomena are\nassociated with an inhomogeneous magnetic landscape within the\nLaAlO$_3$/SrTiO$_3$ nanostructures."
    },
    {
        "anchor": "High-Chern-number bands and tunable Dirac cones in $\u03b2$-graphyne: Graphynes represent an emerging family of carbon allotropes that recently\nattracted much interest due to the tunability of the Dirac cones in the band\nstructure. Here, we show that the spin-orbit couplings in $\\beta$-graphyne\ncould produce various effects related to the topological properties of its\nelectronic bands. Intrinsic spin-orbit coupling yields high- and tunable\nChern-number bands, which may host both topological and Chern insulators, in\nthe presence and absence of time-reversal symmetry, respectively. Furthermore,\nRashba spin-orbit coupling can be used to control the position and the number\nof Dirac cones in the Brillouin zone. These findings suggest that\nspin-orbit-related physics in $\\beta$-graphyne is very rich, and, in\nparticular, that this system could provide a platform for the realization of a\ntwo-dimensional material with tunable topological properties.",
        "positive": "Tuning spinaron and Kondo resonances via quantum confinement: Controlling zero bias anomalies in magnetic atoms provides a promising\nstrategy to engineer tunable quantum many-body excitations. Here we show how\ntwo different quantum impurities featuring spinaron and Kondo excitations can\nbe controlled via quantum confinement engineering by using circular quantum\ncorrals on a Ag(111) surface. In corrals built from both Ag and Co adatoms, the\nwidth of the zero bias anomaly in the central Co adatom oscillates as a\nfunction of corral radius with a period of half of the Ag(111) surface state\nwavelength. Parameters extracted for Co/Ag(111) show only small differences in\nextracted spinaron zero-bias anomaly between corral walls built from Ag or Co\nadatoms. In quantum corrals occupied with metal-free phthalocyanine, a\nparadigmatic $S=1/2$ Kondo system, we observe notable changes in the zero bias\nanomaly lineshape as a function of corral radius. Our results offer insight\ninto many-body Kondo and spinaron resonances where the electronic density is\ncontrolled by confinement engineering."
    },
    {
        "anchor": "Experimental observation of the interaction of propagating spin waves\n  with N\u00e9el domain walls in a Landau domain structure: The interaction of propagating dipolar spin waves with magnetic domain walls\nis investigated in square-shaped microstructures patterned from the Heusler\ncompound Co$_2$Mn$_{0.6}$Fe$_{0.4}$Si. Using magnetic force microscopy, the\nreversible preparation of a Landau state with four magnetic domains separated\nby N\\'eel domain walls is confirmed. A local spin-wave excitation using a\nmicrostructured antenna is realized in one of the domains. It is shown by\nBrillouin light scattering microscopy (BLS) that the domain structure in the\nremanence state has a strong influence on the spin-wave excitation and\npropagation. The domain walls strongly reflect the spin waves and can be used\nas spin-wave reflectors. A comparison with micromagnetic simulations shows that\nthe strong reflection is due to the long-range dipolar interaction which has\nimportant implications for the use of these spin waves for exerting an\nall-magnonic spin-transfer torque.",
        "positive": "Two-dimensional electron gas in a metal/amorphous oxide interface with\n  spin orbit interaction: The formation of novel two-dimensional electron gas (2DEG) with high mobility\nin metal/amorphous interfaces has motivated an ongoing debate regarding the\nformation and novel characteristics of these 2DEGs. Here we report an optical\nstudy, based on infrared spectroscopic ellipsometry, of nonmagnetic metal and\namorphous semiconducting oxide (Cu/Bi$_2$O$_3$) interfaces that confirms the\nformation of a 2DEG with spin orbit coupling (SOC). The 2DEG optical response\nwas simulated with a uniaxial diagonal dielectric tensor within a sub-nanometer\nthin layer, where its $x$ and $z$ components lineshapes resolved in both\nfree-electron and peak-like contributions, resulted very similar to theoretical\npredictions [M. Xie et al., Phys. Rev. B $\\bf{89}$, 245417 (2014)] of a two\ndimensional electron gas confined in the normal direction of a perovskite\ninterface. In particular, the small but finite conducting character of the $z$\ncomponent provides a unambiguous signature of the presence of the 2DEG in the\nCu/Bi$_2$O$_3$ system. Although the original constituent materials do not\npossess spin-orbit coupling (SOC), the resulting interfacial hybridization of\nsuch states induce electronic asymmetric wave functions. This work demonstrates\nthe detection of 2DEG in amorphous crystals allowing to study its challenging\ninterfacial phenomena such as SOC and interface-bulk coupling, overcoming an\nexperimental impediment which has hold back for decades important advancements\nfor the understanding of 2DEGs in amorphous materials."
    },
    {
        "anchor": "Eigenvalues of strictly regular Hall-plates: This work is about uniform, plane, singly connected, strictly regular\nHall-plates with an arbitrary number of peripheral contacts exposed to a\nuniform magnetic field of arbitrary strength. The strictly regular symmetry is\nthe highest possible degree of symmetry, and it is found in commercial\nHall-plates for magnetic field sensors or circulators. It means that all\ncontacts and contact spacings are equally large, if the Hall-plate is mapped\nconformally to the unit disk. The indefinite conductance matrices of such\nHall-plates are circulant matrices, whose complex eigenvalues can be computed\nin closed form. It is shown how to express the conductance and resistance\nmatrices of these Hall-plates, how to compute their equivalent resistor\ncircuit, their Hall-output voltages or currents, their signal-to-thermal noise\nratio, and their power as functions of the eigenvalues. It is also proven that\nthe noise efficiency of strictly regular Hall-plates with many contacts can be\nup to 112% better than for conventional Hall-plates with four contacts, and it\nis explained why their optimal biasing uses patterns of supply voltages or\ncurrents, which vary sinusoidally along their boundary.",
        "positive": "Tunable Strong Magnon-Magnon Coupling in Two-Dimensional Array of\n  Diamond Shaped Ferromagnetic Nanodots: Hybrid magnonics involving coupling between magnons and different quantum\nparticles have been extensively studied during past few years for varied\ninterests including quantum electrodynamics. In such systems, magnons in\nmagnetic materials with high spin density are utilized where the coupling\nstrength is collectively enhanced by the square root of the number of spins to\novercome the weaker coupling between individual spins and the microwave field.\nHowever, achievement of strong magnon-magnon coupling in a confined nanomagnets\nwould be essential for on-chip integration of such hybrid systems. Here,\nthrough intensive study of interaction between different magnon modes in a\nNi80Fe20 (Py) nanodot array, we demonstrate that the intermodal coupling can\napproach the strong coupling regime with coupling strength up to 0.82 GHz and\ncooperativity of 2.51. Micromagnetic simulations reveal that the intermodal\ncoupling is mediated by the exchange field inside each nanodot. The coupling\nstrength could be continuously tuned by varying the bias field strength and\norientation, opening routes for external control over hybrid magnonic systems.\nThese findings could greatly enrich the rapidly evolving field of quantum\nmagnonics."
    },
    {
        "anchor": "Disorder-tuned selection of order in bilayer graphene: The nature of the interaction-driven spontaneously broken-symmetry state in\ncharge neutral bilayer graphene (BLG) has attracted a lot of interest.\nTheoretical studies predict various ordered states as the candidates for the\nground state of BLG in the absence of external fields. Several experiments have\nbeen performed by different groups to identify the nature of the collective\nground state in BLG. However, so far, there is no consensus: some experiments\nshow evidence that suggests the establishment of a nematic gapless state, while\nothers present results that are more consistent with the establishment of a\nfully gapped state. Moreover, even among the experiments that appear to see a\nbulk gap, some of the samples are found to be conducting (suggesting existence\nof gapless edge states), while others are insulating. Here we explore the\nhypothesis that disorder might explain the discrepancy between experiments. We\nfind that the pair breaking effect due to non-magnetic short-range disorder\nvaries among the candidate ground states, giving rise to different amounts of\nsuppression of their mean-field transition temperatures. Our results indicate\nthat BLG can undergo a transition between different ordered states as a\nfunction of the disorder strength providing a possible scenario to resolve the\ndiscrepancy between experimental observations.",
        "positive": "Minibands in twisted bilayer graphene probed by magnetic focusing: Magnetic fields force ballistic electrons injected from a narrow contact to\nmove along skipping orbits and form caustics. This leads to pronounced\nresistance peaks at nearby voltage probes as electrons are effectively focused\ninside them, a phenomenon known as magnetic focusing. This can be used not only\nfor the demonstration of ballistic transport but also to study the electronic\nstructure of metals. Here we use magnetic focusing to probe narrow bands in\ngraphene bilayers twisted at 2 degrees. Their minibands are found to support\nlong-range ballistic transport limited at low temperatures by intrinsic\nelectron-electron scattering. A voltage bias between the layers causes strong\nvalley splitting and allows selective focusing for different valleys, which is\nof interest for using this degree of freedom in frequently-discussed\nvalleytronics."
    },
    {
        "anchor": "Structural stability and uniformity of magnetic Pt13 nanoparticles in\n  NaY zeolite: Based on first-principles simulations, the structural stability and magnetic\nuniformity of Pt13 nanoparticles encapsulated in a NaY zeolite were\ninvestigated. Among 50 stable isomers in the gas phase, only 15 could be\naccommodated into a zeolite pore and severe structural rearrangements occured\ndepending on whether the solid angle at the Pt vertex bound to the supercage\nwas larger than 2 sr (i.e. icosahedron). When van der Waals forces were\nincluded, the global minimum was found to be a new L-shaped cubic wire that is\nunstable in the gas phase. The total magnetization of the encapsulated Pt13\ndecreases due to the stabilization of less coordinated isomers, with the\nmajority of clusters charaterized by a total magnetization of 2 {\\mu}B, while\nthe majority of free clusters exhibit a threefold value.",
        "positive": "Calculation of Binding Energies for Fractional Quantum Hall States with\n  Even Denominators: Fractional quantum Hall states with even denominators have the following\nspecific properties: states with filling factors nu=5/8, 7/10, 3/8, 3/10, and\nso on have respective local minima in the experimental curve of diagonal\nresistivity Rxx versus magnetic field strength. These states are not standard\ncomposite fermion states and are described in the expanded framework. For that\nreason, the binding energies of these states are not obtained. Therefore, it is\nmeaningful to calculate those binding energies using various means. We\ncalculate the binding energies of electron pairs in nearest neighbor orbitals\nor nearest neighbor hole pairs using the second-order perturbation method for\nthe Coulomb interactions among many electrons. The calculated binding energies\nper electron are (1/10)Z2 for nu=5/8, (2/35)Z2 for nu=7/10, (1/6)Z2 for nu=3/8\nand (2/15)Z2 for nu=3/10 and so on, but they are zero for nu=1/2, nu=1/4,\nnu=3/4, nu=1/6, nu=5/6, nu=1/8, nu=7/8, nu=1/10, nu=9/10, nu=1/12 and nu=11/12.\nThe higher order calculations also show the same behavior as in the second\norder. These results further elucidate some aspects of experimental data."
    },
    {
        "anchor": "Dynamic melting and condensation of topological dislocation modes: Bulk dislocation lattice defects are instrumental in identifying\ntranslationally active topological insulators (TATIs), featuring band inversion\nat a finite momentum (${\\bf K}_{\\rm inv}$). As such, TATIs host robust gapless\nmodes around the dislocation core, when the associated Burgers vector ${\\bf b}$\nsatisfies ${\\bf K}_{\\rm inv} \\cdot {\\bf b}=\\pi$ (modulo $2 \\pi$). From the time\nevolution of appropriate density matrices, we show that when a TATI via a real\ntime ramp enters into a trivial or translationally inert topological insulating\nphase, devoid of gapless dislocation modes, the signatures of the preramp\ndefect modes survive for a long time. More intriguingly, as the system ramps\ninto a TATI phase from any translationally inert insulator, signature of the\ndislocation mode dynamically builds up near its core, which is prominent for\nslow ramps. We exemplify these generic outcomes for two-dimensional\ntime-reversal symmetry breaking insulators. Proposed dynamic responses at the\ndislocation core can be experimentally observed in quantum crystals, optical\nlattices and metamaterials with time a tunable band gap.",
        "positive": "Symmetry of electron bands in graphene: (nearly) free electron vs.\n  tight-binding: We present the symmetry labelling of all electron bands in graphene obtained\nby combining numerical band calculations and analytical analysis based on group\ntheory. The latter was performed both in the framework of the (nearly) free\nelectron model, or in the framework of the tight-binding model. The predictions\nabout relative positions of the bands which can be made on the basis of each of\nthe models just using the group theory (and additional simple qualitative\narguments, if necessary) are complimentary."
    },
    {
        "anchor": "Strain engineered graphene using a nanostructured substrate: I\n  Deformations: Using atomistic simulations we investigate the morphological properties of\ngraphene deposited on top of a nanostructured substrate. Sinusoidally\ncorrugated surfaces, steps, elongated trenches, one dimensional and cubic\nbarriers, spherical bubbles, Gaussian bump and Gaussian depression are\nconsidered as support structures for graphene. The graphene-substrate\ninteraction is governed by van der Waals forces and the profile of the graphene\nlayer is determined by minimizing the energy using molecular dynamics\nsimulations. Based on the obtained optimum configurations, we found that: (i)\nfor graphene placed over sinusoidally corrugated substrates with corrugation\nwave lengths longer than 2\\,nm, the graphene sheet follows the substrate\npattern while for supported graphene it is always suspended across the peaks of\nthe substrate, (ii) the conformation of graphene to the substrate topography is\nenhanced when increasing the energy parameter in the van der Waals model, (iii)\nthe adhesion of graphene into the trenches depends on the width of the trench\nand on graphene's orientation, i.e. in contrast to a small width (3 nm)\nnanoribbon with armchair edges, the one with zig-zag edges follows the\nsubstrate profile, (iv) atomic scale graphene follows a Gaussian bump substrate\nbut not the substrate with a Gaussian depression, and (v) the adhesion energy\ndue to van der Waals interaction varies in the range [0.1-0.4] J/m^2.",
        "positive": "Dynamic Characteristics of the Low-Temperature Decomposition of the C20\n  Fullerene: A novel algorithm has been proposed for simulating thermal decomposition of\natomic clusters at such low temperatures that the corresponding lifetimes are\nmacroscopic and, hence, standard molecular dynamics algorithms are\ninapplicable. The proposed algorithm is based on a combination of the molecular\ndynamics and Monte Carlo techniques. It is used to calculate the temperature\ndependence of the lifetime of the thermalized C20 fullerene until it decomposes\nat T = 1300-4000 K. The frequency factor and activation energy of the\ndecomposition are determined. It is demonstrate that the temperature\ndependences of the lifetimes of the heat-isolated and thermalized fullerenes\ndiffer significantly."
    },
    {
        "anchor": "Many-body correlations and coupling in benzene-dithiol junctions: Most theoretical studies of nanoscale transport in molecular junctions rely\non the combination of the Landauer formalism with Kohn-Sham density functional\ntheory (DFT) using standard local and semilocal functionals to approximate\nexchange and correlation effects. In many cases, the resulting conductance is\noverestimated with respect to experiments. Recent works have demonstrated that\nthis discrepancy may be reduced when including many-body corrections on top of\nDFT. Here we study benzene-dithiol (BDT) gold junctions and analyze the effect\nof many-body perturbation theory (MBPT) on the calculation of the conductance\nwith respect to different bonding geometries. We find that the many-body\ncorrections to the conductance strongly depend on the metal-molecule coupling\nstrength. In the BDT junction with the lowest coupling, many-body corrections\nreduce the overestimation on the conductance to a factor two, improving the\nagreement with experiments. In contrast, in the strongest coupling cases,\nmany-body corrections on the conductance are found to be sensibly smaller and\nstandard DFT reveals a valid approach.",
        "positive": "Vibrational features in inelastic electron tunneling spectra: A theoretical analysis of inelastic electron tunneling spectroscopy (IETS)\nexperiments conducted on molecular junctions are presented, where the second\nderivative of the current with respect to voltage is usually plotted as a\nfunction of applied bias. Within the nonperturbative computational scheme,\nadequate for arbitrary parameters of the model, we consider the virtual\nconduction process in the off-resonance region. Here we study the influence of\nfew crucial factors on the IETS spectra: the strength of the vibronic coupling,\nthe phonon energy, and the device working temperature. It was also shown that\nweak asymmetry in the IETS signal with respect to bias polarity is obtained as\na result of strongly asymmetric connection with the electrodes."
    },
    {
        "anchor": "Long-wavelength gauge symmetry and translations in a magnetic field for\n  Dirac electrons in graphene: In two-dimensional (2D) electron systems in a magnetic field, the Coulomb\ninteraction among charge carriers, under Landau quantization, essentially\ngoverns a variety of many-body phenomena while there are also phenomena, such\nas the (integer) quantum Hall effect, that appear unaffected by the\ninteraction. It is pointed out that the response of 2D electrons to\nspatially-uniform potentials and fields enjoys a long-wavelength gauge\nsymmetry, associated with cyclotron motion of electrons, that leaves the\nCoulomb interaction invariant and that thus naturally explains why cyclotron\nresonance (as implied by Kohn's theorem) and the quantized Hall conductance\nappear insensitive to the interaction. It is discussed, in the light of this\nnew long-wavelength gauge symmetry, how Dirac electrons in graphene and\nconventional 2D electrons differ in cyclotron-resonance characteristics and the\nquantum Hall effect.",
        "positive": "Spin current generation from sputtered Y3Fe5O12 films: Spin current injection from sputtered yttrium iron garnet (YIG) films into an\nadjacent platinum layer has been investigated by means of the spin pumping and\nthe spin Seebeck effects. Films with a thickness of 83 and 96 nanometers were\nfabricated by on-axis magnetron rf sputtering at room temperature and\nsubsequent post-annealing. From the frequency dependence of the ferromagnetic\nresonance linewidth, the damping constant has been estimated to be\n$(7.0\\pm1.0)\\times 10^{-4}$. Magnitudes of the spin current generated by the\nspin pumping and the spin Seebeck effect are of the same order as values for\nYIG films prepared by liquid phase epitaxy. The efficient spin current\ninjection can be ascribed to a good YIG|Pt interface, which is confirmed by the\nlarge spin-mixing conductance $(2.0\\pm0.2)\\times 10^{18}$ m$^{-2}$."
    },
    {
        "anchor": "A Platform for Far-Infrared Spectroscopy of Quantum Materials at\n  Millikelvin Temperatures: Optical spectroscopy of quantum materials at ultralow temperatures is rarely\nexplored, yet it may provide critical characterizations of quantum phases not\npossible using other approaches. We describe the development of a novel\nexperimental platform that enables optical spectroscopic studies, together with\nstandard electronic transport, of materials at millikelvin temperatures inside\na dilution refrigerator. The instrument is capable of measuring both bulk\ncrystals and micron-sized two-dimensional van der Waals materials and devices.\nWe demonstrate the performance by implementing photocurrent-based Fourier\ntransform infrared spectroscopy on a monolayer WTe$_2$ device and a multilayer\n1T-TaS$_2$ crystal, with a spectral range available from the near-infrared to\nthe terahertz regime and in magnetic fields up to 5 T. In the far-infrared\nregime, we achieve spectroscopic measurements at a base temperature as low as ~\n43 mK and a sample electron temperature of ~ 450 mK. Possible experiments and\npotential future upgrades of this versatile instrumental platform are\nenvisioned.",
        "positive": "Spin-Strain Phase Diagram of Defective Graphene: Using calculations on defective graphene from first principles, we herein\nconsider the dependence of the properties of the monovacancy of graphene under\nisotropic strain, with a particular focus on spin moments. At zero strain, the\nvacancy shows a spin moment of 1.5 $\\mu_B$ that increases to $\\sim$2 $\\mu_B$\nwhen the graphene is in tension. The changes are more dramatic under\ncompression, in that the vacancy becomes non-magnetic when graphene is\ncompressed more than 2%. This transition is linked to changes in the atomic\nstructure that occurs around vacancies, and is associated with the formation of\nripples. For compressions slightly greater than 3%, this rippling leads to the\nformation of a heavily reconstructed vacancy structure that consists of two\ndeformed hexagons and pentagons. Our results suggest that any defect-induced\nmagnetism that occurs in graphene can be controlled by applying a strain, or\nsome other mechanical deformations."
    },
    {
        "anchor": "Resonant Electron Transport in Single-Molecule Junctions: Vibrational\n  Excitation, Rectification, Negative Differential Resistance and Local Cooling: Vibronic effects in resonant electron transport through single-molecule\njunctions are analyzed. The study is based on generic models for molecular\njunctions, which include electronic states on the molecular bridge that are\nvibrationally coupled and exhibit Coulomb interaction. The transport\ncalculations employ a master equation approach. The results, obtained for a\nseries of models with increasing complexity, show a multitude of interesting\ntransport phenomena, including vibrational excitation, rectification, negative\ndifferential resistance (NDR) as well as local cooling. While some of these\nphenomena have been observed or proposed before, the present analysis extends\nprevious studies and allows a more detailed understanding of the underlying\ntransport mechanisms. In particular, it is shown that many of the observed\nphenomena can only be explained if electron-hole pair creation processes at the\nmolecule-lead interface are taken into account. Furthermore, vibronic effects\nin sytems with multiple electronic states and their role for the stability of\nmolecular junctions are analyzed.",
        "positive": "Antiferromagnetism-induced second-order nonlinear optical responses of\n  centrosymmetric bilayer CrI$_3$: Antiferromagnetism (AF) in AB'-stacked centrosymmetric bilayer (BL) CrI$_3$\nbreaks both spatial inversion ($P$) and time-reversal ($T$) symmetries but\nmaintains the combined $PT$ symmetry, thus inducing novel second-order\nnonlinear optical (NLO) responses such as second-harmonic generation (SHG),\nlinear electric-optic effect (LEO) and bulk photovoltaic effect (BPVE). In this\nwork, we calculate AF-induced NLO responses of the BL CrI$_3$ based on the\ndensity functional theory with the generalized gradient approximation (GGA)\nplus onsite Coulomb correlation (U), i.e., the GGA+U method. Interestingly, we\nfind that the magnetic SHG, LEO and photocurrent in the AF BL CrI$_3$ are huge,\nbeing comparable or even larger than that of the well-known nonmagnetic\nnoncentrosymmetric semiconductors. For example, the calculated SHG coefficients\nare in the same order of magnitude as that of MoS$_2$ monolayer (ML), the most\npromising 2D material for NLO devices. The calculated LEO coefficients are\nalmost three times larger than that of MoS$_2$ ML. The calculated NLO\nphotocurrent in the CrI$_3$ BL is among the largest values predicted so far for\nthe BPVE materials. On the other hand, unlike nonmagnetic semiconductors, the\nNLO responses in the AF BL CrI$_3$ are nonreciprocal and also switchable by\nrotating magnetization direction. Therefore, our interesting findings indicate\nthat the AF BL CrI$_3$ will not only provide a valuable platform for exploring\nnew physics of low-dimensional magnetism but also have promising applications\nin magnetic NLO and LEO devices such as frequency conversion, electro-optical\nswitches, and light signal modulators as well as high energy conversion\nefficiency photovoltaic solar cells."
    },
    {
        "anchor": "Vibrational and electronic ultrafast relaxation of the nitrogen-vacancy\n  centers in diamond: Two dimensional electronic spectroscopy and transient grating measurements\nwere performed, for the first time, on nitrogen-vacancy centers in diamond.\nThese measurements reveal energy transfer and vibrational pathways with\nconsequences for spin coherence.",
        "positive": "Domain wall propagation through spin wave emission: We theoretically study field-induced domain wall (DW) motion in an\nelectrically insulating ferromagnet with hard- and easy-axis anisotropies. DWs\ncan propagate along a dissipationless wire through spin wave emission locked\ninto the known soliton velocity at low fields. In the presence of damping, the\nmode appears before the Walker breakdown field for strong out-of-plane magnetic\nanisotropy, and the usual Walker rigid-body propagation mode becomes unstable\nwhen the field is between the maximal-DW-speed field and Walker breakdown\nfield."
    },
    {
        "anchor": "Electrical Spin Injection in Multi-Wall carbon NanoTubes with\n  transparent ferromagnetic contacts: We report on electrical spin injection measurements on MWNTs . We use a\nferromagnetic alloy Pd$_{1-x}$Ni$_{x}$ with x $\\approx$ 0.7 which allows to\nobtain devices with resistances as low as 5.6 $k\\Omega$ at 300 $K$. The yield\nof device resistances below 100 $k\\Omega$, at 300 $K$, is around 50%. We\nmeasure at 2 $K$ a hysteretic magneto-resistance due to the magnetization\nreversal of the ferromagnetic leads. The relative difference between the\nresistance in the antiparallel (AP) orientation and the parallel (P)\norientation is about 2%.",
        "positive": "Isolated and hybrid bilayer graphene rings: Using the continuum model, we investigate the electronic properties of two\ntypes of bilayer graphene (BLG) quantum ring (QR) geometries: (i) an isolated\nBLG QR and (ii) a monolayer graphene (MLG) with a QR put on top of an infinite\ngraphene sheet (hybrid BLG QR). Solving the Dirac-Weyl equation in the presence\nof a perpendicular magnetic field and applying the infinite-mass boundary\ncondition at the ring boundaries, we obtain analytical results for the energy\nlevels and corresponding wave spinors for both structures. In the case of\nisolated BLG QR, we observe a sizeable and magnetically tunable band gap which\nagrees with the tight-binding transport simulations. Our analytical results\nalso show the intervalley symmetry $ E^K_e (m) = -E^{K'}_h(m) $ between the\nelectron (e) and hole (h) states ($ m $ being the angular momentum quantum\nnumber) for the energy spectrum of the isolated BLG QR. The presence of\ninterface boundary in a hybrid BLG QR modifies drastically the energy levels as\ncompared to that of an isolated BLG QR. Its energy levels are tunable from MLG\ndot, to isolated BLG QR, and to MLG Landau energy levels as magnetic field is\nvaried. Our predictions can be verified experimentally using different\ntechniques such as by magnetotransport measurements."
    },
    {
        "anchor": "Dominant non-local superconducting proximity effect due to\n  electron-electron interaction in a ballistic double nanowire: Cooper pair splitting (CPS) can induce non-local correlation between two\nnormal conductors coupling to a superconductor. CPS into a double\none-dimensional electron gas is an appropriate platform for extracting large\namount of entangled electron pairs and one of the key ingredients for\nengineering Majorana Fermions with no magnetic field. Here we study CPS using a\nJosephson junction of a gate-tunable ballistic InAs double nanowire. The\nmeasured switching current into the two nanowires significantly larger than sum\nof that into the respective nanowires, indicating the inter-wire\nsuperconductivity dominant compared to the intra-wire superconductivity. From\ndependence on the number of propagating channels in the nanowires, the observed\nCPS is assigned to one-dimensional electron-electron interaction. Our results\nwill pave the way for utilizing one-dimensional electron-electron interaction\nto reveal physics of high-efficient CPS and engineer Majorana Fermions in\ndouble nanowire systems via CPS.",
        "positive": "Origin of the gap in the surface states of the antiferromagnetic\n  topological insulator: We study the influence of the antiferromagnetic order on the surface states\nof topological insulators. We derive an effective Hamiltonian for these states,\ntaking into account the space structure of the antiferromagnetic ordering. We\nobtain a typical (gapless) Dirac Hamiltonian for the surface states if the\nsurface of the sample is not perturbed. However, a shift in the chemical\npotential of the surface layer opens a gap in the spectrum away from Fermi\nenergy. Such a gap arises only in systems with a finite antiferromagnetic\norder. We observe that the gap is robust against the surface disorder. The\nobtained results are consistent with the recent experiments and density\nfunctional theory calculations."
    },
    {
        "anchor": "Optical Charge Injection and Full Coherent Control of Spin-Qubit in the\n  Telecom C-band Emitting Quantum Dot: Solid-state quantum emitters with manipulable spin-qubits are promising\nplatforms for quantum communication applications. Although such light-matter\ninterfaces could be realized in many systems only a few allow for light\nemission in the telecom bands necessary for long-distance quantum networks.\nHere, we propose and implement a new optically active solid-state spin-qubit\nbased on a hole confined in a single InAs/GaAs quantum dot grown on an InGaAs\nmetamorphic buffer layer emitting photons in the C-band. We lift the hole\nspin-degeneracy using an external magnetic field and demonstrate hole\ninjection, initialization, read-out and complete coherent control using\npicosecond optical pulses. These results showcase a new solid-state spin-qubit\nplatform compatible with preexisting optical fibre networks.",
        "positive": "Near-complete violation of Kirchhoff s law in thermal radiation in\n  ultrathin magnetic Weyl semimetal films: The ability to break Kirchhoff s law is of fundamental importance in thermal\nradiation. Various nonreciprocal emitters have been proposed to break the\nbalance between absorption and emission. However, the thicknesses of the\nnonreciprocal materials are usually larger than 1/10 times of the wavelength.\nBesides, the previous proposed nonreciprocal emitters are complex, thus they\ncan hardly be fabricated in experiment to verify the Kirchhoff s law for\nnonreciprocal materials. In this paper, we investigate the nonreciprocal\nthermal radiation of the magnetic Weyl semimetal (MWSM) film atop of the metal\nsubstrate. It is found that the strong nonreciprocal radiation at the\nwavelength of 9.15 {\\mu}m can be achieved when the thickness of the MWSM film\nis 100 nm. The enhanced nonreciprocity is attributed to the Fabry-Perot\nresonances. The results indicate that the MWSM film is the promising candidate\nto engineer the ultrathin and simple nonreciprocal thermal emitters. What is\nperhaps most intriguing here is that the proposed structure can be more easily\nfabricated in experiment to verify the Kirchhoff s law for nonreciprocal\nmaterials."
    },
    {
        "anchor": "The Electronic Thickness of Graphene: The van-der-Waals stacking technique enables the fabrication of\nheterostructures, where two conducting layers are atomically close. In this\ncase, the finite layer thickness matters for the interlayer electrostatic\ncoupling. Here we investigate the electrostatic coupling of two graphene\nlayers, twisted by 22 degrees such that the layers are decoupled by the huge\nmomentum mismatch between the K and K' points of the two layers. We observe a\nsplitting of the zero-density lines of the two layers with increasing\ninterlayer energy difference. This splitting is given by the ratio of\nsingle-layer quantum capacitance over interlayer capacitance C and is therefore\nsuited to extract C. We explain the large observed value of C by considering\nthe finite dielectric thickness d of each graphene layer and determine d=2.6\nAngstrom. In a second experiment we map out the entire density range with a\nFabry-P\\'erot resonator. We can precisely measure the Fermi-wavelength in each\nlayer, showing that the layers are decoupled. We find that the Fermi wavelength\nexceeds 600nm at the lowest densities and can differ by an order of magnitude\nbetween the upper and lower layer. These findings are reproduced using\ntight-binding calculations.",
        "positive": "Conditions for Conductance Quantization in Mesoscopic Dirac Systems on\n  the Examples of Graphene Nanoconstrictions: Ballistic transport through an impurity-free section of the Corbino disk in\ngraphene is investigated by means of the Landauer-B\\\"{u}ttiker formalism in the\nmesoscopic limit. In the linear-responce regime the conductance is quantized in\nsteps close to integer multiples of $4e^{2}/h$, yet Fabry-Perot oscillations\nare strongly suppressed. The quantization arises for small opening angles\n$\\theta\\lesssim\\pi/3$ and large radii ratios $R_2/R_1\\gtrsim{}10$. We find that\nthe condition for emergence of the $n$-th conductance step can be written as\n$\\sqrt{n}\\theta/\\pi\\ll{}1$. A brief comparison with the conductance spectra of\ngraphene nanoribbons with parallel edges is also provided."
    },
    {
        "anchor": "Anisotropic Spin Relaxation Induced by Surface Spin-Orbit Effects: It is a common perception that the transport of a spin current in\npolycrystalline metal is isotropic and independent of the polarization\ndirection, even though spin current is a tensorlike quantity and its\npolarization direction is a key variable. We demonstrate surprising anisotropic\nspin relaxation in mesoscopic polycrystalline Cu channels in nonlocal spin\nvalves. For directions in the substrate plane, the spin-relaxation length is\nlonger for spins parallel to the Cu channel than for spins perpendicular to it,\nby as much as 9% at 10 K. Spin-orbit effects on the surfaces of Cu channels can\naccount for this anisotropic spin relaxation. The finding suggests novel\ntunability of spin current, not only by its polarization direction but also by\nelectrostatic gating.",
        "positive": "Quantum heat fluctuations of single particle sources: Optimal single electron sources emit regular streams of particles, displaying\nno low frequency charge current noise. Due to the wavepacket nature of the\nemitted particles, the energy is however fluctuating, giving rise to heat\ncurrent noise. We investigate theoretically this quantum source of heat noise\nfor an emitter coupled to an electronic probe in the hot-electron regime. The\ndistribution of temperature and potential fluctuations induced in the probe is\nshown to provide direct information on the single particle wavefunction\nproperties and display strong non-classical features."
    },
    {
        "anchor": "Tunable entanglement generation for mobile-electron spin qubits: Recent studies have shown that linear electron optics can be used to generate\nentangled two-particle states from nonentangled ones if additional measurements\nof charge or parity are performed. We have investigated such nondeterministic\nentanglement production in electronic versions of the Mach-Zehnder\ninterferometer, where spin-dependent interference occurs due to the presence of\nelectric-field tunable Rashba spin splitting. Adjustment of the spin-precession\nlength turns out to switch the entangler on and off, as well as control the\ndetailed form of entangled output states.",
        "positive": "Voltage-driven exchange resonance achieving 100\\% mechanical efficiency: Magnetic resonances driven by current-induced torques are crucial tools to\nstudy magnetic materials but are very limited in frequency and mechanical\nefficiency. We propose an alternative mechanism, voltage-induced torque, to\nrealize high efficiency in generating high-frequency magnetization dynamics.\nWhen a ferromagnet-topological insulator-ferromagnet trilayer heterostructure\nis operated as an adiabatic quantum motor, voltage-induced torque arises from\nthe adiabatic motion of gapped topological electrons on the two interfaces and\nact oppositely on the two ferromagnetic layers, which can excite the exchange\nmode where the two ferromagnetic layers precess with a $\\pi$-phase difference.\nThe exchange mode resonance, bearing a much higher frequency than the\nferromagnetic resonance, is accompanied by topological charge pumping, leading\nto a sharp peak in electrical admittance at the resonance point. Because the\noutput current is purely adiabatic while dissipative current vanishes\nidentically, the proposed voltage-driven exchange resonance entails a\nremarkably high mechanical efficiency close to unity, which is impossible in\nany current-driven systems."
    },
    {
        "anchor": "Decoherence induced by magnetic impurities in quantum Hall system: Scattering by magnetic impurities is known to destroy coherence of electron\nmotion in metals and semiconductors. We investigate the decoherence introduced\nin a single act of electron scattering by a magnetic impurity in a quantum Hall\nsystem. To this end we introduce a fictitious nonunitary scattering matrix\n$\\mathcal{S}$ for electrons that reproduces the exactly calculated scattering\nprobabilities. The strength of decoherence is identified by the deviation of\neigenvalues of the product $\\mathcal{S}\\mathcal{S}^{\\dagger}$ from unity. Using\nthe fictitious scattering matrix, we estimate the width of the metallic region\nat the quantum Hall effect inter-plateau transition and its dependence on the\nexchange coupling strength and the degree of polarization of magnetic\nimpurities.",
        "positive": "Terahertz dynamics of a topologically protected state: quantum Hall\n  effect plateaus near cyclotron resonance in a GaAs/AlGaAs heterojunction: We measure the Hall conductivity of a two-dimensional electron gas formed at\na GaAs/AlGaAs heterojunction in the terahertz regime close to the cyclotron\nresonance frequency by employing a highly sensitive Faraday rotation method\ncoupled with electrical gating of the sample to change the electron density. We\nobserve clear plateau-and step-like features in the Faraday rotation angle vs.\nelectron density and magnetic field (Landau-level filling factor), which are\nthe high frequency manifestation of quantum Hall plateaus - a signature of\ntopologically protected edge states. The results are compared to a recent\ndynamical scaling theory."
    },
    {
        "anchor": "Realistic picture of helical edge states in HgTe quantum wells: We propose a minimal effective two-dimensional Hamiltonian for HgTe/CdHgTe\nquantum wells (QWs) describing the side maxima of the first valence subband. By\nusing the Hamiltonian, we explore the picture of helical edge states in tensile\nand compressively strained HgTe QWs. We show that both dispersion and\nprobability density of the edge states can differ significantly from those\npredicted by the Bernevig-Hughes-Zhang (BHZ) model. Our results pave the way\ntowards further theoretical investigations of HgTe-based quantum spin Hall\ninsulators with direct and indirect band gaps beyond the BHZ model.",
        "positive": "Transport in Bilayer Graphene: Calculations within a self-consistent\n  Born approximation: The transport properties of a bilayer graphene are studied theoretically\nwithin a self-consistent Born approximation. The electronic spectrum is\ncomposed of $k$-linear dispersion in the low-energy region and $k$-square\ndispersion as in an ordinary two-dimensional metal at high energy, leading to a\ncrossover between different behaviors in the conductivity on changing the Fermi\nenergy or disorder strengths. We find that the conductivity approaches\n$2e^2/\\pi^2\\hbar$ per spin in the strong-disorder regime, independently of the\nshort- or long-range disorder."
    },
    {
        "anchor": "Many-body effects between unbosonized excitons: We here give a brief survey of our new many-body theory for composite\nexcitons, as well as some of the results we have already obtained using it. In\nview of them, we conclude that, in order to fully trust the results one finds,\ninteracting excitons should not be bosonized: Indeed, all effective bosonic\nHamiltonians (even the hermitian ones !) can miss terms as large as the ones\nthey generate; they can even miss the dominant term, as in problems dealing\nwith optical nonlinearities.",
        "positive": "Controlling spin without magnetic fields -- the Bloch-Rashba rotator: We consider the dynamics of a quantum particle held in a lattice potential,\nand subjected to a time-dependent spin-orbit coupling. Tilting the lattice\ncauses the particle to perform Bloch oscillations, and by suitably changing the\nRashba interaction during its motion, the spin of the particle can be gradually\nrotated. Even if the Rashba coupling can only be altered by a small amount,\nlarge spin-rotations can be obtained by accumulating the rotation from\nsuccessive oscillations. We show how the time-dependence of the spin-orbit\ncoupling can be chosen to maximize the rotation per cycle, and thus how this\nmethod can be used to produce a precise and controllable spin-rotator, the\nBloch-Rashba rotator, without requiring an applied magnetic field."
    },
    {
        "anchor": "Spin-orbital Texture in Topological Insulators: Relativistic spin-orbit coupling plays an essential role in the field of\ntopological insulators and quantum spintronics. It gives rise to the\ntopological non-trivial band structure and enables electric manipulation of the\nspin degree of freedom. Because of the spin-orbit coupling, rich spin-orbital\ncoupled textures can exist both in momentum and in real space. For three\ndimensional topological insulators in the Bi$_2$Se$_3$ family, topological\nsurface states with p$_z$ orbitals have a left-handed spin texture for the\nupper Dirac cone and a right-handed spin texture for the lower Dirac cone. In\nthis work, we predict a new form of the spin-orbital texture associated with\nthe p$_x$ and p$_y$ orbitals. For the upper Dirac cone, a left-handed\n(right-handed) spin texture is coupled to the \"radial\" (\"tangential\") orbital\ntexture, whereas for the lower Dirac cone, the coupling of spin and orbital\ntextures is the exact opposite. The \"tangential\" (\"radial\") orbital texture is\ndominant for the upper (lower) Dirac cone, leading to the right-handed spin\ntexture for the in-plane orbitals of both the upper and lower Dirac cones. A\nspin-resovled and photon polarized angle-resolved photoemission spectroscopy\nexperiment is proposed to observe this novel spin-orbital texture.",
        "positive": "Graphane as polyhydride of graphene. Computational synthesis applied to\n  two-side membrane: A great efficacy of molecular quantum chemistry applied to basic graphene\nproblems has been recently demonstrated by the authors when studying the\nformation of peculiar composites between carbon nanotubes and graphene as well\nas considering tensile deformation and fracture of a graphene sheet in due\ncourse of a mechanochemical reaction. The optimistic results obtained in the\nstudies make it possible to shift attention from the solid state problems and\nconsider the graphane formation as multistep hydrogenation of the pristine\nmolecule. To proceed we have to answer the following questions: 1) which kind\nof the hydrogen adsorption, namely, molecular or atomic, is the most probable;\n2) what is a characteristic image of the hydrogen atom attachment to the\nsubstrate; 3) which carbon atom (or atoms) is the first target subjected to the\nhydrogen attachment and how carbon atoms are selected for the next steps of the\nadsorption; 4) is there any connection between the sequential adsorption\npattern and cyclohexane conformers. First results obtained on this way are\npresented in the current paper. The calculations were performed within the\nframework of unrestricted broken symmetry Hartree-Fock approach by using\nsemiempirical AM1 technique."
    },
    {
        "anchor": "Edge states and spin-valley edge photocurrent in transition metal\n  dichalcogenide monolayers: We develop an analytical theory for edge states in monolayers of transition\nmetal dichalcogenides based on a general boundary condition for a two-band\n${\\bf kp}$-Hamiltonian in case of uncoupled valleys. Taking into account {\\it\nedge} spin-orbit interaction we reveal that edge states, in general, have\nlinear dispersion that is determined by three real phenomenological parameters\nin the boundary condition. In absence of the edge spin-orbit interaction, edge\nstates are described by a single real parameter whose sign determines whether\ntheir spectra intersect the bulk gap or not. In the former case we show that\nillumination by circularly polarised light results in spin and valley polarised\nphotocurrent along the edge. Flow direction, spin and valley polarisation of\nthe edge photocurrent are determined by the direction of circular polarisation\nof the illuminated light.",
        "positive": "Topological characterization of dynamic chiral magnetic textures using\n  machine learning: Recently proposed spintronic devices use magnetic skyrmions as bits of\ninformation. The reliable detection of those chiral magnetic objects is an\nindispensable requirement. Yet, the high mobility of magnetic skyrmions leads\nto their stochastic motion at finite temperatures, which hinders the precise\nmeasurement of the topological numbers. Here, we demonstrate the successful\ntraining of artificial neural networks to reconstruct the skyrmion number in\nconfined geometries from time-integrated, dimensionally reduced data. Our\nresults prove the possibility to recover the topological charge from a\ntime-averaged measurement and hence smeared dynamic skyrmion ensemble, which is\nof immediate relevance to the interpretation of experimental results,\nskyrmion-based computing, and memory concepts"
    },
    {
        "anchor": "Response of incompressible fractional quantum Hall states to magnetic\n  and non-magnetic impurities: Using exact diagonalization we examine the response of several most prominent\nfractional quantum Hall states to a single local impurity. The 2/3 singlet\nstate is found to be more inert than the polarized one in spite of its smaller\nincompressibility gap. Based on its spin-spin correlation functions we\ninterpret it as a liquid of electron pairs with opposite spin. A comparison of\ndifferent types of impurities, non-magnetic and magnetic, is presented.",
        "positive": "Quasiparticle band-edge energy and band offsets of monolayer of\n  molybdenum and tungsten chalcogenide: We report the quasiparticle energy of monolayer of molybdenum and tungsten\ndichalcogenides, MX2 (M=Mo, W; X=S, Se, Te). Beyond calculating bandgaps, we\nhave achieved converged absolute band energies relative to the vacuum level.\nCompared with the results from other approaches, the GW calculation reveals\nsubstantially larger bandgaps and different absolute band energies because of\nenhanced many-electron effects. Interestingly, our fully-converged\nquasiparticle energies ratify the band-gap-center approximation, making it a\nconvenient way to estimate quasiparticle energy. The absolute quasiparticle\nenergies and band offsets obtained in this work are important for designing\nheterojunction devices and chemical catalysts based on monolayer\ndichalcogenides."
    },
    {
        "anchor": "Controllable Andreev retroreflection and specular Andreev reflection in\n  a four-terminal graphene-superconductor hybrid system: We report the investigation of electron transport through a four-terminal\ngraphene-superconductor hybrid system. Due to the quantum interference of the\nreflected holes from two graphene-superconductor interfaces with phase\ndifference $\\theta$, it is found that the specular Andreev reflection vanishes\nat $\\theta=0$ while the Andreev retroreflection disappears at $\\theta=\\pi$.\nThis means that the retroreflection and specular reflection can be easily\ncontrolled and separated in this device. In addition, due to the diffraction\neffect in the narrow graphene nanoribbon, the reflected hole can exit from both\ngraphene terminals. As the width of nanoribbon increases, the diffraction\neffect gradually disappears and the reflected hole eventually exits from a\nparticular graphene terminal depending on the type of Andreev reflection.",
        "positive": "Veselago Lens for Electrons: Focusing and Caustics in Graphene p-n\n  Junctions: The focusing of electric current by a single \\textit{p-n} junction in\ngraphene is predicted. We show that precise focusing can be achieved by\nfine-tuning the densities of carriers on the n- and p-sides of the junction to\nequal values, whereas the current distribution in junctions with different\ndensities resembles caustics in optics. This finding can be utilized in the\nengineering of electronic lenses and focused beam-splitters using\ngate-controlled \\textit{n-p-n} junctions in graphene-based transistors."
    },
    {
        "anchor": "Tunneling of interacting fermions in 1D systems: Using the self-consistent Hartree-Fock approximation for spinless electrons\nat zero temperature, we study tunneling of the interacting electron gas through\na single delta-barrier in a finite one-dimensional (1D) wire connected to\ncontacts. Our results exhibit features known from correlated many-body models.\nIn particular, the conductance decays with the wire length as $\\propto\nL^{-2\\alpha}$, where the power $\\alpha$ is universal. We also show that a\nsimilar result for a wire conductance can be extracted from the persistent\ncurrent (I) through the delta-barrier in a 1D ring, where it is known that I\n\\propto L^{-1-\\alpha}$.",
        "positive": "Noise-induced Renyi entropy flow of a quantum heat engine: Entropy is one of the central quantities in thermodynamics, whose flow\nbetween two systems determines the statistics of energy transfers. In quantum\nsystems entropy is non-linear in density matrix whose time evolution is\ncumbersome. Using recent developments in the Keldysh formalism for the\nevolution of nonlinear quantum information measures (Phys. Rev. B 91, 174307\n(2015)), we study the flow of von Neumann and Renyi entropies in a generic\nfour-level quantum system that is weakly coupled to equilibrium heat engines.\nWe show that noise-induced coherence has significant influence on the entropy\nflow of the quantum heat engine. We determine analytical optimization of\ncouplings for the purpose of designing optimal artificial energy transfer\nsystems."
    },
    {
        "anchor": "Topological phase in one-dimensional interacting fermion system: We study a one-dimensional interacting topological model by means of exact\ndiagonalization method. The topological properties are firstly examined with\nthe existence of the edge states at half-filling. We find that the topological\nphases are not only robust to small repulsive interactions but also are\nstabilized by small attractive interactions, and also finite repulsive\ninteraction can drive a topological non-trivial phase into a trivial one while\nthe attractive interaction can drive a trivial phase into a non-trivial one.\nNext we calculate the Berry phase and parity of the bulk system and find that\nthey are equivalent in characterizing the topological phases. With them we\nobtain the critical interaction strengths and construct part of the phase\ndiagram in the parameters space. Finally we discuss the effective Hamiltonian\nat large-U limit and provide additional understanding of the numerical results.\nOur these results could be realized experimentally using cold atoms trapped in\nthe 1D optical lattice.",
        "positive": "Thermal transport in a granular metal array: We obtain the Kubo formula for the electronic thermal conductivity kappa(T)\nof a granular metal array at low temperatures for the Ambegaokar-Eckern-Schoen\n(AES) model and study the kinetic and potential contributions in the\ndiamagnetic (local) and paramagnetic (current-current) terms. For small values\nof dimensionless intergrain tunneling conductance, g << 1, we show that\ninelastic cotunneling processes contribute to thermal conductivity due to\nnon-cancellation of the diamagnetic and paramagnetic terms, unlike electrical\nconductivity. We find that the electrical conductivity obeys the Arrhenius law,\nsigma(T) ~ ge^{-E_c/T}, however kappa(T) decreases only algebraically, kappa(T)\n\\~ g^2 T^3/E_c^2. At large values of intergrain coupling, g >> 1, we find it\nplausible that the Wiedemann-Franz law weakly deviates from the free-electron\ntheory due to Coulomb effects."
    },
    {
        "anchor": "Electronic Specific Heat of DNA: Effects of backbones and disorder: In this present work we report the results of our investigation on the\nelectronic specific heat (ESH) of DNA molecule modelled within the\ntight-binding framework. We take four different DNA sequences ranging from\nperiodic, quasi-periodic to random and studied both ESH and also the density of\nstates to supplement our ESH results. The role of the backbone structure and\nthe effectsof environment on ESH are discussed. We observe that irrespective of\nthe sequences there is auniversal response of the ESH spectra for a given\ndisorder. The nature of response of specific heaton backbone disorder is\ntotally opposite in low and high temperature regimes.",
        "positive": "AFM probe for the signatures of Wigner correlations in the conductance\n  of a one-dimensional quantum dot: The transport properties of an interacting one-dimensional quantum dot\ncapacitively coupled to an atomic force microscope probe are investigated. The\ndot is described within a Luttinger liquid framework which captures both\nFriedel and Wigner oscillations. In the linear regime, we demonstrate that both\nthe conductance peak position and height oscillate as the tip is scanned along\nthe dot. A pronounced beating pattern in the conductance maximum is observed,\nconnected to the oscillations of the electron density. Signatures of the\neffects induced by a Wigner molecule are clearly identified and their stability\nagainst the strength of Coulomb interactions are analyzed. While the\noscillations of the peak position due to Wigner get enhanced at strong\ninteractions, the peak height modulations are suppressed as interactions grow.\nOscillations due to Friedel, on the other hand, are robust against interaction."
    },
    {
        "anchor": "Enhancement of spin-orbit torque efficiency by tailoring interfacial\n  spin-orbit coupling in Pt-based magnetic multilayers: We study inserting Co layer thickness-dependent spin transport and spin-orbit\ntorques (SOTs) in the Pt/Co/Py trilayers by spin-torque ferromagnetic\nresonance. The interfacial perpendicular magnetic anisotropy energy density\n($K_s = 2.7~erg/cm^2$), which is dominated by interfacial spin-orbit coupling\n(ISOC) in the Pt/Co interface, total effective spin-mixing conductance\n($G_{eff,tot} = 0.42 {\\times} 10^{15}~{\\Omega}^{-1} m^{-2}$) and two-magnon\nscattering (${\\beta}_{TMS} = 0.46~nm^2$) are first characterized, and the\ndamping-like torque (${\\xi}_{DL}$ = 0.103) and field-like torque (${\\xi}_{FL}$\n= -0.017) efficiencies are also calculated quantitatively by varying the\nthickness of the inserting Co layer. The significant enhancement of\n${\\xi}_{DL}$ and ${\\xi}_{FL}$ in Pt/Co/Py than Pt/Py bilayer system originates\nfrom the interfacial Rashba-Edelstein effect due to the strong ISOC between\nCo-3d and Pt-5d orbitals at the Pt/Co interface. Additionally, we find a\nconsiderable out-of-plane spin polarization SOT, which is ascribed to the spin\nanomalous Hall effect and possible spin precession effect due to IPMA-induced\nperpendicular magnetization at the Pt/Co interface. Our results demonstrate\nthat the ISOC of the Pt/Co interface plays a vital role in spin transport and\nSOTs-generation. Our finds offer an alternative approach to improve the\nconventional SOTs efficiencies and generate unconventional SOTs with\nout-of-plane spin polarization to develop low power Pt-based spintronic via\ntailoring the Pt/FM interface.",
        "positive": "Oscillation of the tunnel splitting in nanospin systems within the\n  particle mapping formalism: The oscillation of tunnel splitting in the biaxial spin system within\nmagnetic field along the anisotropy axis is analyzed within the particle\nmapping approach, rather than in the (\\theta-\\phi) spin coherent-state\nrepresentation. In our mapping procedure, the spin system is transformed into a\nparticle moving in the restricted $S^1$ geometry whose wave function subjects\nto the boundary condition involving additional phase shift. We obtain the new\ntopological phase that plays the same role as the Wess-Zumino action in spin\ncoherent-state representation. Considering the interference of two possible\ntrajectories, instanton and anti-instanton, we get the identical condition for\nthe field at which tunneling is quenched, with the previous result within spin\ncoherent-state representation."
    },
    {
        "anchor": "Building Blocks of Topological Quantum Chemistry: Elementary Band\n  Representations: The link between chemical orbitals described by local degrees of freedom and\nband theory, which is defined in momentum space, was proposed by Zak several\ndecades ago for spinless systems with and without time-reversal in his theory\nof \"elementary\" band representations. In Nature 547, 298-305 (2017), we\nintroduced the generalization of this theory to the experimentally relevant\nsituation of spin-orbit coupled systems with time-reversal symmetry and proved\nthat all bands that do not transform as band representations are topological.\nHere, we give the full details of this construction. We prove that elementary\nband representations are either connected as bands in the Brillouin zone and\nare described by localized Wannier orbitals respecting the symmetries of the\nlattice (including time-reversal when applicable), or, if disconnected,\ndescribe topological insulators. We then show how to generate a band\nrepresentation from a particular Wyckoff position and determine which Wyckoff\npositions generate elementary band representations for all space groups. This\ntheory applies to spinful and spinless systems, in all dimensions, with and\nwithout time reversal. We introduce a homotopic notion of equivalence and show\nthat it results in a finer classification of topological phases than approaches\nbased only on the symmetry of wavefunctions at special points in the Brillouin\nzone. Utilizing a mapping of the band connectivity into a graph theory problem,\nwhich we introduced in Nature 547, 298-305 (2017), we show in companion papers\nwhich Wyckoff positions can generate disconnected elementary band\nrepresentations, furnishing a natural avenue for a systematic materials search.",
        "positive": "Valley-Selective Topological Ordered States in Irradiated Bilayer\n  Graphene: Gapless bilayer graphene is susceptible to a variety of spontaneously gapped\nstates. As predicted by theory and observed by experiment, the ground state is\nhowever topologically trivial, because a valley-independent gap is\nenergetically favorable. Here, we show that under the application of interlayer\nelectric field and circularly polarized light, one valley can be selected to\nexhibit the original interaction instability while the other is frozen out.\nTuning this Floquet system stabilizes multiple competing topological ordered\nstates, distinguishable by edge transport and circular dichroism. Notably,\nquantized charge, spin, and valley Hall conductivities coexist in one\nstabilized state."
    },
    {
        "anchor": "Magnetoresistance Oscillations in Two-dimensional Electron Systems\n  Induced by AC and DC Fields: We report on magnetotransport measurements in a high-mobility two-dimentional\nelectron system subject simultaneously to AC (microwave) and DC (Hall) fields.\nWe find that DC excitation affects microwave photoresistance in a nontrivial\nway. Photoresistance maxima (minima) evolve into minima (maxima) and back,\nreflecting strong coupling and interplay of AC- and DC-induced effects. Most of\nour observations can be explained in terms of indirect electron transitions\nusing a new, ``combined'' resonant condition. Observed quenching of\nmicrowave-induced zero resistance by a DC field cannot be unambiguously linked\nto a domain model, at least until a systematic theory treating both excitation\ntypes within a single framework is developed.",
        "positive": "Self-assembly of InAs nanostructures on the sidewalls of GaAs nanowires\n  directed by a Bi surfactant: Surface energies play a dominant role in the self-assembly of three\ndimensional (3D) nanostructures. In this letter, we show that using surfactants\nto modify surface energies can provide a means to externally control\nnanostructure self-assembly, enabling the synthesis of novel hierarchical\nnanostructures. We explore Bi as a surfactant in the growth of InAs on the\n{1-10} sidewall facets of GaAs nanowires. The presence of surface Bi induces\nthe formation of InAs 3D islands by a process resembling the Stranski-Krastanov\nmechanism, which does not occur in the absence of Bi on these surfaces. The\nInAs 3D islands nucleate at the corners of the {1-10} facets above a critical\nshell thickness and then elongate along <110> directions in the plane of the\nnanowire sidewalls. Exploiting this growth mechanism, we realize a series of\nnovel hierarchical nanostructures, ranging from InAs quantum dots on single\n{1-10} nanowire facets to zig-zag shaped nanorings completely encircling\nnanowire cores. Photoluminescence spectroscopy and cathodoluminescence spectral\nline scans reveal that small surfactant-induced InAs 3D islands behave as\noptically active quantum dots. This work illustrates how surfactants can\nprovide an unprecedented level of external control over nanostructure\nself-assembly."
    },
    {
        "anchor": "Spin current pumping in helical Luttinger liquids: We study the DC spin current induced into an unbiased quantum spin Hall\nsystem through a two-point contacts setup with time dependent electron\ntunneling amplitudes. By means of two external gates, it is possible to drive a\ncurrent with spin-preserving and spin-flipping contributions showing peculiar\noscillations as a function of pumping frequency, electron-electron interaction\nand temperature. From its interference patterns as a function of the\nFabry-Perot and Aharonov-Bohm phases, it is possible to extract information\nabout the helical nature of the edge states and the intensity of the\nelectron-electron interaction.",
        "positive": "Evaluation of a gate capacitance in the sub-aF range for a chemical\n  field-effect transistor with a silicon nanowire channel: An evaluation of the gate capacitance of a field-effect transitor (FET) whose\nchannel length and width are several ten nanometer, is a key point for sensors\napplications. However, experimental and precise evaluation of capacitance in\nthe aF range or less has been extremely difficult. Here, we report an\nextraction of the capacitance down to 0.55 aF for a silicon FET with a\nnanoscale wire channel whose width and length are 15 and 50 nm, respectively.\nThe extraction can be achieved by using a combination of four kinds of\nmeasurements: current characteristics modulated by double gates,\nrandom-telegraph-signal noise induced by trapping and detrapping of a single\nelectron, dielectric polarization noise, and current characteristics showing\nCoulomb blockade at low temperature. The extraction of such a small gate\ncapacitance enables us to evaluate electron mobility in a nanoscale wire using\na classical model of current characteristics of a FET."
    },
    {
        "anchor": "Diagnosis for topological semimetals in the absence of spin-orbital\n  coupling: Topological semimetals are under intensive theoretical and experimental\nstudies. The first step of these studies is always the theoretical (numerical)\npredication of one of several candidate materials, starting from first\nprinciples. In these calculations, it is crucial that all topological band\ncrossings, including their types and positions in the Brillouin zone, are\nfound. While band crossings along high-symmetry lines, which are routinely\nscanned in numerics, are simple to locate, the ones at generic momenta are\nnotoriously time-consuming to find, and may be easily missed. In this paper, we\nestablish a theoretical scheme of diagnosis for topological semimetals where\nall band crossings are at generic momenta in systems with time-reversal\nsymmetry and negligible spin-orbital coupling. The scheme only uses the\nsymmetry (inversion and rotation) eigenvalues of the valence bands at\nhigh-symmetry points in the BZ as input, and provides the types, numbers and\nconfigurations of all topological band crossings, if any, at generic momenta.\nThe nature of new diagnosis scheme allows for full automation and\nparallelizations, and paves way to high throughput numerical predictions of\ntopological materials.",
        "positive": "Interaction-induced zero-energy pinning and quantum dot formation in\n  Majorana nanowires: Majorana modes emerge in non-trivial topological phases at the edges of some\nspecific materials, like proximitized semiconducting nanowires under a external\nmagnetic field. Ideally, they are non-local states that are charge neutral\nsuperpositions of electrons and holes. However, in nanowires of realistic\nlength their wave functions overlap and acquire a finite charge that, under\ncertain circumstances, makes them susceptible to interactions, specifically\nwith the image charges that arise in the electrostatic environment. Considering\na realistic three-dimensional model of the dielectric surroundings, here we\nshow that this interaction leads to a suppression of the Majorana oscillations\npredicted by simpler theoretical models, and to the formation of low-energy\nquantum dot states that interact with the Majorana modes. Both features are\nobserved in recent experiments on the detection of Majoranas and could thus\nhelp to properly characterize them."
    },
    {
        "anchor": "Suppressing Andreev bound state zero bias peaks using a strongly\n  dissipative lead: Hybrid semiconductor-superconductor nanowires are predicted to host Majorana\nzero modes, manifested as zero-bias peaks (ZBPs) in tunneling conductance. ZBPs\nalone, however, are not sufficient evidence due to the ubiquitous presence of\nAndreev bound states in the same system. Here, we implement a strongly\nresistive normal lead in our InAs-Al nanowire devices and show that most of the\nexpected ZBPs, corresponding to zero-energy Andreev bound states, can be\nsuppressed, a phenomenon known as environmental Coulomb blockade. Our result is\nthe first experimental demonstration of this dissipative interaction effect on\nAndreev bound states and can serve as a possible filter to narrow down ZBP\nphase diagram in future Majorana searches.",
        "positive": "Landau level mixing and spin degeneracy in the quantum Hall effect: We study dynamics of electrons in a magnetic field using a network model with\ntwo channels per link with random mixing in a random intrachannel potential;\nthe channels represent either two Landau levels or two spin states. We consider\nchannel mixing as function of the energy separation of the two extended states\nand show that its effect changes from repulsion to attraction as the energy\nseparation increases. For two Landau levels this leads to level floating at low\nmagnetic fields while for Zeeman split spin states we predict level attraction\nat high magnetic fields, accounting for ESR data. We also study random mixing\nof two degenerate channels, while the intrachannel potential is periodic\n(non-random). We find a single extended state with a localization exponent\n$\\nu\\approx 1.1$ for real scattering at nodes; the general case has also a\nsingle extended state, though the localized nature of nearby states sets in at\nunusually large scales."
    },
    {
        "anchor": "Bound states induced giant oscillations of the conductance in the\n  quantum Hall regime: We theoretically studied the quasiparticle transport in a 2D electron gas\nbiased in the quantum Hall regime and in the presence of a lateral potential\nbarrier. The lateral junction hosts the specific magnetic field dependent\nquasiparticle states highly localized in the transverse direction. The quantum\ntunnelling across the barrier provides a complex bands structure of a\none-dimensional energy spectrum of these bound states, $\\epsilon_n(p_y)$, where\n$p_y$ is the electron momentum in the longitudinal direction $y$. Such a\nspectrum manifests itself by a large number of peaks and drops in the\ndependence of the magnetic edge states transmission coefficient $D(E)$ on the\nelectron energy $E$. E.g., the high value of $D$ occurs as soon as the electron\nenergy $E$ reaches gaps in the spectrum. These peaks and drops of $D(E)$ result\nin giant oscillations of the transverse conductance $G_x$ with the magnetic\nfield and/or the transport voltage. Our theoretical analysis based on the\ncoherent macroscopic quantum superposition of the bound states and the magnetic\nedge states propagating along the system boundaries, is in a good accord with\nthe experimental observations found in Ref. W. Kang et al., Letters to Nature,\n403, 59 (2000).",
        "positive": "Measurement of Temporal Correlations of the Overhauser Field in a Double\n  Quantum Dot: In quantum dots made from materials with nonzero nuclear spins, hyperfine\ncoupling creates a fluctuating effective Zeeman field (Overhauser field) felt\nby electrons, which can be a dominant source of spin qubit decoherence. We\ncharacterize the spectral properties of the fluctuating Overhauser field in a\nGaAs double quantum dot by measuring correlation functions and power spectra of\nthe rate of singlet-triplet mixing of two separated electrons. Away from zero\nfield, spectral weight is concentrated below 10 Hz, with 1/f^2 dependence on\nfrequency, f. This is consistent with a model of nuclear spin diffusion, and\nindicates that decoherence can be largely suppressed by echo techniques."
    },
    {
        "anchor": "Carrier mobility and scattering lifetime in electric double-layer gated\n  few-layer graphene: We fabricate electric double-layer field-effect transistor (EDL-FET) devices\non mechanically exfoliated few-layer graphene. We exploit the large capacitance\nof a polymeric electrolyte to study the transport properties of three, four and\nfive-layer samples under a large induced surface charge density both above and\nbelow the glass transition temperature of the polymer. We find that the carrier\nmobility shows a strong asymmetry between the hole and electron doping regime.\nWe then employ ab-initio density functional theory (DFT) calculations to\ndetermine the average scattering lifetime from the experimental data. We\nexplain its peculiar dependence on the carrier density in terms of the specific\nproperties of the electrolyte we used in our experiments.",
        "positive": "Topology detection in cavity QED: We explore the physics of topological lattice models in c-QED architectures\nfor arbitrary coupling strength, and the use of the cavity transmission as a\ntopological marker. For this, we develop an approach combining the input-output\nformalism with an expansion in quantum fluctuations which allows to go beyond\nthe small-coupling regime. We apply our formalism to a fermionic\nSu-Schrieffer-Heeger (SSH) chain coupled to a single-mode cavity, and find that\nthe cavity can indeed act as a quantum sensor for topological phases, where the\ninitial state preparation plays a crutial role. Additionally, we discuss the\npersistence of topological features as the coupling strength increases, in\nterms of an effective Hamiltonian, and calculate the entanglement entropy."
    },
    {
        "anchor": "Berry curvature induced valley Hall effect in non-encapsulated\n  hBN/Bilayer graphene heterostructure aligned with near-zero twist angle: Valley Hall effect has been observed in asymmetric single-layer and bilayer\ngraphene systems. In single-layer graphene systems, asymmetry is introduced by\naligning graphene with hexagonal boron nitride (hBN) with a near-zero twist\nangle, breaking the sub-lattice symmetry. Although a similar approach has been\nused in bilayer graphene to break the layer symmetry and thereby observe the\nvalley Hall effect, the bilayer graphene was sandwiched with hBN on both sides\nin those studies. This study looks at a much simpler, non-encapsulated\nstructure where hBN is present only at the top of graphene. The\ncrystallographic axes of both hBN and bilayer graphene are aligned. A clear\nsignature of the valley Hall effect through non-local resistance measurement\n($R_{\\rm{NL}}$) was observed. The observed non-local resistance could be\nmanipulated by applying a displacement field across the heterostructure.\nFurthermore, the electronic band structure and Berry curvature calculations\nvalidate the experimental observations.",
        "positive": "Anomalous Josephson current through a driven double quantum dot: Josephson junctions based on quantum dots offer a convenient tunability by\nmeans of local gates. Here we analyze a Josephson junction based on a serial\ndouble quantum dot in which the two dots are individually gated by\nphase-shifted microwave tones of equal frequency. We calculate the\ntime-averaged current across the junction and determine how the phase shift\nbetween the drives modifies the current-phase relation of the junction.\nBreaking particle-hole symmetry on the dots is found to give rise to a finite\naverage anomalous Josephson current with phase bias between the superconductors\nfixed to zero. This microwave gated weak link thus realizes a tunable \"Floquet\n$\\varphi_{0}$-junction\" with maximum critical current achieved for driving\nfrequencies slightly off-resonance with the energy cost of exciting a sub-gap\nstate on each dot. We provide numerical results supported by an analytical\nanalysis for infinite superconducting gap and weak inter-dot coupling. We\nidentify an interaction driven $0-\\pi$ transition of anomalous Josephson\ncurrent as a function of driving phase difference. Finally, we show that this\njunction can be tuned so as to provide for complete rectification of the\ntime-averaged Josephson current phase relation."
    },
    {
        "anchor": "Angle Dependence of Photonic Enhancement of Magneto-Optical Kerr Effect\n  in DMS Layers: We investigate theoretically an angle dependence of enhancement of polar\nmagneto-optical Kerr effect (MOKE) obtained thanks to a deposition of a\nparamagnetic Diluted Magnetic Semiconductor (DMS) layer on one-dimensional\nphotonic crystal layer. Our transfer matrix method based calculations conducted\nfor TE and TM polarizations of the incident light predict up to an order of\nmagnitude stronger MOKE for a (Ga,Fe)N DMS layer when implementing the proposed\ndesign. The maximum enhancement for TE and TM polarization occurs for the light\nincidence at the normal and at the Brewster angle, respectively. This indicates\na possibility of tuning of the MOKE enhancement by adjustment of the\npolarization and the incidence angle of the light.",
        "positive": "On the electrical conductivity of metals with a rough surface: We discuss surface roughness effects on the conduction of electrons in metals\nusing both the quantal Kubo-Greenwood formalism and the semi-classical\nFuchs-Sondheimer method. The main purpose here is to compare these methods and\nclarify a few subtle conceptual issues. One of such issues is concerned with\nthe conditions under which the broken translation symmetry along a rough\nsurface may be restored. This symmetry has often been presumed in existing work\nbut not always with proper justifications. Another one relates to the physical\nmeaning of a phenomenological parameter (denoted by $p$) intuitively introduced\nin the semi-classical theory. This parameter, called the specularity parameter\nor sometimes the \\textit{Fuchs} parameter, plays an important role in the\nexperimental studies of surface roughness but has so far lacked a rigorous\nmicroscopic definition. The third issue arises as to the domain of validity for\nthe electrical conductivity obtained in those methods. A misplacement of the\ndomain may have resulted in erroneous analysis of surface effects in a variety\nof electrodynamic phenomena including surface plasma waves."
    },
    {
        "anchor": "Unravelling the edge spectra of non-Hermitian Chern insulators: Non-Hermitian Chern insulators differ from their Hermitian cousins in one key\naspect: their edge spectra are incredibly rich and confounding. For example,\neven in the simple case where the bulk spectrum consists of two bands with\nChern number $\\pm 1$, the edge spectrum in the slab geometry may have one or\ntwo edge states on both edges, or only at one of the edges, depending on the\nmodel parameters. This blatant violation of the familiar bulk-edge\ncorrespondence casts doubt on whether the bulk Chern number can still be a\nuseful topological invariant, and demands a working theory that can predict and\nexplain the myriad of edge spectra from the bulk Hamiltonian to restore the\nbulk-edge correspondence. We outline how such a theory can be set up to yield a\nthorough understanding of the edge phase diagram based on the notion of the\ngeneralized Brillouin zone (GBZ) and the asymptotic properties of block\nToeplitz matrices. The procedure is illustrated by solving and comparing three\nnon-Hermitian generalizations of the Qi-Wu-Zhang model, a canonical example of\ntwo-band Chern insulators. We find that, surprisingly, in many cases the phase\nboundaries and the number and location of the edge states can be obtained\nanalytically. Our analysis also reveals a non-Hermitian semimetal phase whose\nenergy-momentum spectrum forms a continuous membrane with the edge modes\ntransversing the hole, or genus, of the membrane. Subtleties in defining the\nChern number over GBZ, which in general is not a smooth manifold and may have\nsingularities, are demonstrated using examples. The approach presented here can\nbe generalized to more complicated models of non-Hermitian insulators or\nsemimetals in two or three dimensions.",
        "positive": "Internal field induced enhancement and effect of resonance in Raman\n  scattering of InAs nanowires: An internal field induced resonant intensity enhancement of Raman scattering\nof phonon excitations in InAs nanowires is reported. The experimental\nobservation is in good agreement with the simulated results for the scattering\nof light under varying incident wavelengths, originating from the enhanced\ninternal electric field in an infinite dielectric cylinder. Our analysis\ndemonstrates the combined effect of the first higher lying direct band gap\nenergy (E1) and the refractive index of the InAs nanowires in the internal\nfield induced resonant Raman scattering. Furthermore, the difference in the\nrelative contribution of electro-optic effect and deformation potential in\nRaman scattering of nanowires and bulk InAs over a range of excitation energies\nis discussed by comparing the intensity ratio of their LO and TO phonon modes."
    },
    {
        "anchor": "Dominant role of the shear strain induced admixture in spin-flip\n  processes in self-assembled quantum dots: We study theoretically the spin-flip relaxation processes for a single\nelectron in a self-assembled InAs/GaAs quantum dot, using an 8-band kp theory\nin the envelope function approximation. We show that the dominating channel of\nspin relaxation is spin admixture induced by symmetry-breaking shear strain,\nwhich can be mapped onto two effective spin-phonon terms in a conduction band\n(effective mass) Hamiltonian that have a similar structure and interfere\nconstructively. Unlike the Dresselhaus coupling that dominates spin relaxation\nin larger, unstrained dots, the shear strain contribution cannot be modeled by\na unique standard term in the Hamiltonian but rather relies on the actual\nstrain distribution in the quantum dot.",
        "positive": "Remote-control spin filtering through a $T$-type structure: We propose a spin filter scheme using a $T$-stub waveguide. By applying a\nmoderate magnetic field at the tip of the sidearm, this device can produce both\nlarge electric and spin current. The direction, polarization of the output spin\ncurrent can be further adjusted electronically by a remote gate which tunes the\nlength of the sidearm. The device is robust against the disorder."
    },
    {
        "anchor": "Interface dependence of the Josephson-current fluctuations in short SNS\n  junctions: We discuss the dependence of the Josephson current correlations in mesoscopic\nsuperconductor/normal-conductor/superconductor (SNS) devices on the\ntransparency of the superconductor/normal-conductor (SN) interfaces. Focusing\non short junctions we apply the supersymmetry method to construct an effective\nfield theory for mesoscopic SNS devices which is evaluated in the limit of\nhighly and weakly transparent interfaces. We show that the two-point\nJosephson-current correlator differs by an universal factor 2 in these two\ncases.",
        "positive": "Ultrafast carrier dynamics in pristine and FeCl3-intercalated bilayer\n  graphene: Ultrafast carrier dynamics of pristine bilayer graphene (BLG) and bilayer\ngraphene intercalated with FeCl3 (FeCl3-G), were studied using time-resolved\ntransient differential reflection (delta R/R). Compared to BLG, the FeCl3-G\ndata showed an opposite sign of delta R/R, a slower rise time, and a single\n(instead of double) exponential relaxation. We attribute these differences in\ndynamics to the down-shifting of the Fermi level in FeCl3-G, as well as the\nformation of numerous horizontal bands arising from the d-orbitals of Fe. Our\nwork shows that intercalation can dramatically change the electronic structure\nof graphene, and its associated carrier dynamics."
    },
    {
        "anchor": "Structural details of Al/Al2O3 junctions and their role in formation of\n  electron tunnel barriers: We present a computational study of the adhesive and structural properties of\nthe Al/Al2O3 interfaces as building blocks of the Metal-Insulator-Metal (MIM)\ntunnel devices, where electron transport is accomplished via tunnelling\nmechanism through the sandwiched insulating barrier. The main goal of this\npaper is to understand, on the atomic scale, the role of the geometrical\ndetails in the formation of the tunnel barrier profiles. To provide reliable\nresults, we carefully assess the accuracy of the traditional methods used to\nexamine Al/Al2O3 interfaces. These are the most widely employed\nexchange-correlation functionals, LDA, PBE and PW91, the Universal Binding\nEnergy Relation (UBER) for predicting equilibrium interfacial distances and\nadhesion energies, and the ideal work of separation as a measure of junction\nstability. Finally, we perform a detailed analysis of the atomic and\ninterplanar relaxations in each junction. Our results imply that the structural\nirregularities on the surface of the Al film have a significant contribution to\nlowering the tunnel barrier height, while interplanar relaxations in the Al\nfilm, away from the immediate interface do not have a notable impact on the\ntunnelling properties. On the other hand, up to 5-7 layers of Al2O3 may be\ninvolved in shaping the tunnel barriers. Interplanar relaxations of these\nlayers depend on the geometry of the interface and may result in the net\ncontraction by 13% relative to the corresponding thickness in the bulk oxide.\nThis is a significant amount as the tunnelling probability depends\nexponentially on the barrier width.",
        "positive": "Magnetic-proximity-induced magnetoresistance on topological insulators: We theoretically study the magnetoresistance (MR) of two-dimensional massless\nDirac electrons as found on the surface of three-dimensional topological\ninsulators (3D TIs) that is capped by a ferromagnetic insulator (FI). We\ncalculate charge and spin transport by Kubo and Boltzmann theories, taking into\naccount the ladder-vertex correction and the in-scattering due to normal and\nmagnetic disorder. The induced exchange splitting is found to generate an\nelectric conductivity that depends on the magnetization orientation, but its\nform is very different from both the anisotropic and spin Hall MR. The in-plane\nMR vanishes identically for non-magnetic disorder, while out-of-plane\nmagnetizations cause a large MR ratio. On the other hand, we do find an\nin-plane MR and planar Hall effect in the presence of magnetic disorder aligned\nwith the FI magnetization. Our results may help understand recent transport\nmeasurements on TI|FI systems."
    },
    {
        "anchor": "Tunable topological phononic crystals: Topological insulators, first observed in electronic systems, have inspired\nmany analogues in photonic and phononic crystals in which remarkable one-way\npropagation edge states are supported by topologically nontrivial bandgaps.\nSuch bandgaps can be achieved by breaking the time-reversal symmetry to lift\nthe degeneracy associated with Dirac cones at the corners of the Brillouin\nzone. Here, we report on our construction of a phononic crystal exhibiting a\nDirac-like cone in the Brillouin zone center. We demonstrate that\nsimultaneously breaking the time-reversal symmetry and altering the geometric\nsize of the unit cell result in a topological transition that is verified by\nthe Chern number calculation and edge mode analysis. The topology of the\nbandgap is tunable by varying both the velocity field and the geometric size;\nsuch tunability may dramatically enrich the design and use of acoustic\ntopological insulators.",
        "positive": "Thermal effects and spontaneous frictional relaxation in atomically thin\n  layered materials: We study the thermal effects on the frictional properties of atomically thin\nsheets. We simulate a simple model based on the Prandtl-Tomlinson model that\nreproduces the layer dependence of friction and strengthening effects seen in\nAFM experiments. We investigate sliding at constant speed as well as reversing\ndirection. We also investigate contact aging: the changes that occur to the\ncontact when the sliding stops completely. We compare the numerical results to\nanalytical calculations based on Kramers rates. We find that there is a slower\nthan exponential contact aging that weakens the contact and that we expect will\nbe observable in experiments. We discuss the implications for sliding as well\nas aging experiments."
    },
    {
        "anchor": "Comparison of finite-temperature topological indicators based on Uhlmann\n  connection: Two indicators of finite-temperature topological properties based on the\nUhlmann connection, one generalizing the Wilson loop to the Uhlmann-Wilson loop\nand the other generalizing the Berry phase to the Uhlmann phase, are\nconstructed explicitly for a time-reversal invariant topological insulators\nwith a $Z_2$ index. While the phases of the eigenvalues of the Wilson loop\nreflect the $Z_2$ index of the model at zero temperature, it is found that the\nsignature from the Uhlmann-Wilson loop gradually fades away as temperature\nincreases. On the other hand, the Berry phase exhibits quantization due to the\nunderlying holonomy group. The Uhlmann phase retains the quantization at finite\ntemperatures and serves as an indicator of topological properties. A phase\ndiagram showing where jumps of the Uhlmann phase can be found is presented. By\nmodifying the model to allow higher winding numbers, finite-temperature\ntopological regimes sandwiched between trivial regimes at high and low\ntemperatures may emerge.",
        "positive": "Boosting the voltage gain of graphene FETs through a differential\n  amplifier scheme with positive feedback: We study a possible circuit solution to overcome the problem of low voltage\ngain of short-channel graphene FETs. The circuit consists of a fully\ndifferential amplifier with a load made of a cross-coupled transistor pair.\nStarting from the device characteristics obtained from self-consistent\nballistic quantum transport simulations, we explore the circuit parameter space\nand evaluate the amplifier performance in terms of dc voltage gain and voltage\ngain bandwidth. We show that the dc gain can be effectively improved by the\nnegative differential resistance provided by the cross-coupled pair. Contact\nresistance is the main obstacle to achieving gain bandwidth products in the\nterahertz range. Limitations of the proposed amplifier are identified with its\npoor linearity and relatively large Miller capacitance."
    },
    {
        "anchor": "Theory of non-retarded ballistic surface plasma waves in metal films: We present a theory of surface plasma waves in metal films with arbitrary\nelectronic collision rate $\\tau$. Both \\textit{tangential} and \\textit{normal}\nmodes are investigated. A universal self-amplification channel for these waves\nis established as a result of the unique interplay between ballistic electronic\nmotions and boundary effects. The channel is shown to be protected by a general\nprinciple and its properties independent of $\\tau$. The effects of film\nthickness and surface roughness are also calculated. Experimental implications,\nsuch as Ferrel radiation, are discussed.",
        "positive": "Low-Temperature Collapse of Electron Localisation in Two Dimensions: We report direct experimental evidence that the insulating phase of a\ndisordered, yet strongly interacting two-dimensional electron system (2DES)\nbecomes unstable at low temperatures. As the temperature decreases, a\ntransition from insulating to metal-like transport behaviour is observed, which\npersists even when the resistivity of the system greatly exceeds the quantum of\nresistivity h/e^2. The results have been achieved by measuring transport on a\nmesoscopic length-scale while systematically varying the strength of disorder."
    },
    {
        "anchor": "Polariton linewidth and the reservoir temperature dynamics in a\n  semiconductor microcavity: A method of determining the temperature of the nonradiative reservoir in a\nmicrocavity exciton-polariton system is developed. A general relation for the\nhomogeneous polariton linewidth is theoretically derived and experimentally\nused in the method. In experiments with a GaAs microcavity under nonresonant\npulsed excitation, the reservoir temperature dynamics is extracted from the\npolariton linewidth. Within the first nanosecond the reservoir temperature\ngreatly exceeds the lattice temperature and determines the dynamics of the\nmajor processes in the system. It is shown that, for nonresonant pulsed\nexcitation of GaAs microcavities, the polariton Bose-Einstein condensation is\ntypically governed by polariton-phonon scattering, while interparticle\nscattering leads to condensate depopulation.",
        "positive": "Entanglement swapping between electromagnetic field modes and matter\n  qubits: Scalable quantum networks require the capability to create, store and\ndistribute entanglement among distant nodes (atoms, trapped ions, charge and\nspin qubits built on quantum dots, etc.) by means of photonic channels. We show\nhow the entanglement between qubits and electromagnetic field modes allows\ngeneration of entangled states of remotely located qubits. We present\nanalytical calculations of linear entropy and the density matrix for the\nentangled qubits for the system described by the Jaynes-Cummings model. We also\ndiscuss the influence of decoherence. The presented scheme is able to drive an\ninitially separable state of two qubits into an highly entangled state suitable\nfor quantum information processing."
    },
    {
        "anchor": "Approaches for modeling magnetic nanoparticle dynamics: Magnetic nanoparticles are useful biological probes as well as therapeutic\nagents. There have been several approaches used to model nanoparticle\nmagnetization dynamics for both Brownian as well as N\\'eel rotation. The\nmagnetizations are often of interest and can be compared with experimental\nresults. Here we summarize these approaches including the Stoner-Wohlfarth\napproach, and stochastic approaches including thermal fluctuations.\nNon-equilibrium related temperature effects can be described by a distribution\nfunction approach (Fokker-Planck equation) or a stochastic differential\nequation (Langevin equation). Approximate models in several regimes can be\nderived from these general approaches to simplify implementation.",
        "positive": "Self-detecting gate-tunable nanotube paddle resonators: We have fabricated suspended metal paddle resonators with carbon nanotubes\nfunctioning as self-detecting torsional springs. We observe gate-tunable\nresonances, that either tune to higher or to lower frequencies when increasing\nthe dc voltage on the back-gate. We attribute the former modes to flexural\nvibrations of the paddle resonator, while the latter ones are identified as\ntorsional vibrations. Compared to top-down silicon fabricated paddle\nresonators, nanotube springs have smaller torsional spring constants and\nprovide a larger frequency tunability."
    },
    {
        "anchor": "Four-Dimensional Topological Insulators with Nodal-Line Boundary States: Conventional topological insulators and superconductors have topologically\nprotected nodal points on their boundaries, and the recent interests in\nnodal-line semimetals only concerned bulk band structures. Here, we present a\nnovel four-dimensional topological insulator protected by an anti-unitary\nreflection symmetry, whose boundary band has a single $PT$-symmetric nodal line\nwith double topological charges. Inspired by the recent experimental\nrealization of the four-dimensional quantum Hall effect, we also propose a\ncold-atom system which realizes the novel topological insulator with tunable\nparameters as extra dimensions.",
        "positive": "Coexistence of Topological and Normal Insulating Phases in\n  Electro-Optically Tuned InAs/GaSb Bilayer Quantum Wells: We report on the coexistence of both normal and topological insulating phases\nin InAs/GaSb bilayer quantum well induced by the built-in electric field tuned\noptically and electrically. The emergence of topological and normal insulating\nphases is assessed based on the evolution of the charge carrier densities, the\nresistivity dependence of the gap via in-plane magnetic fields and the thermal\nactivation of carriers. For the Hall bar device tuned optically, we observe the\nfingerprints associated with the presence of only the topological insulating\nphase. For another Hall bar processed identically but with an additional top\ngate, the coexistence of normal and topological insulating phases is found by\nelectrical tuning. Our finding paves the way for utilizing a new\nelectro-optical tuning scheme to manipulate InAs/GaSb bilayer quantum wells to\nobtain trivial-topological insulating interfaces in the bulk rather than at the\nphysical edge of the device."
    },
    {
        "anchor": "Graphene for Emission of Terahertz Radiation: Graphene is a two-dimensional crystal consisting of a monatomic layer of\ncarbon atoms. Electrons and holes in graphene behave as quasi-relativistic\nparticles with zero effective mass and large (as compared to semiconductors)\nFermi velocity. These unique physical properties can be used for designing\ndetectors, emitters and modulators of terahertz radiation. Here we discuss\nseveral ideas of using graphene based structures for emission of terahertz\nradiation.",
        "positive": "Emergence of intrinsically isolated flat bands and their topology in\n  fully relaxed twisted multi-layer graphene: We study the electronic structure and band topology of fully relaxed twisted\nmulti-layer graphene (TMLG). Isolated flat bands emerge in TMLG with the number\nof layers [$M+N$ with $M$ the layer number of the bottom few-layer graphene\n(FLG)] up to 10 and with various stacking orders, and most of them are on the\nhole side. The touched bands of FLGs around the Fermi level are split by the\nmoir\\'{e} coupling through the electron-hole asymmetry in low-energy bands of\nFLGs and by the vertical hopping between next-nearest layers. The full\nstructural relaxation leads to global gaps that completely isolate a flat band.\nFor TMLG with given $M$ and $N$, the highest magnitude of Chern numbers ($|C|$)\nof the separable flat bands reaches $M+N-1$ and can be hosted by certain\nisolated bands. The $|C|=9$ occurs in the isolated flat valence band of several\nconfigurations with 10 layers. Such high $|C|$ originates from the lifting of\nthe band-state degeneracy in the weak regime of moir\\'{e} coupling or from the\ntopological phase transitions induced by the strong moir\\'{e} coupling.\nMoreover, large orbital magnetic moments arise in isolated flat bands with high\n$|C|$ and depend on the structural configurations of TMLG."
    },
    {
        "anchor": "Heat Capacity Evidence for the Suppression of Skyrmions at Large Zeeman\n  Energy: Measurements on a multilayer two-dimensional electron system (2DES) near\nLandau level filling $\\nu$=1 reveal the disappearance of the nuclear spin\ncontribution to the heat capacity as the ratio $\\tilde{g}$ between the Zeeman\nand Coulomb energies exceeds a critical value $\\tilde{g}_c \\approx$0.04. This\ndisappearance suggests the vanishing of the Skyrmion-mediated coupling between\nthe lattice and the nuclear spins as the spin excitations of the 2DES make a\ntransition from Skyrmions to single spin-flips above $\\tilde{g}_c$. Our\nexperimental $\\tilde{g}_c$ is smaller than the calculated $\\tilde{g}_c$=0.054\nfor an ideal 2DES; we discuss possible origins of this discrepancy.",
        "positive": "Spin-dependent electron transport through a ferromagnetic domain wall: We present a theoretical study of spin-dependent transport through a\nferromagnetic domain wall. With an increase of the number of components of the\nexchange coupling, we have observed that the variance of the conductance\nbecomes half. As the strength of the domain wall magnetization is increased,\nnegative magnetoresistance is also observed."
    },
    {
        "anchor": "Conductance recovery and spin polarization in boron and nitrogen codoped\n  graphene nanoribbons: We present an ab initio study of the structural, electronic, and quantum\ntransport properties of B-N-complex edge-doped graphene nanoribbons (GNRs). We\nfind that the B-N edge codop-ing is energetically a very favorable process and\nfurthermore can achieve novel doping effects that are absent for the single B\nor N doping. The compensation effect between B and N is predicted to generally\nrecover the excellent electronic transport properties of pristine GNRs. For the\nzigzag GNRs, however, the spatially localized B-N defect states selectively\ndestroy the doped-side spin-polarized GNR edge currents at the valence and\nconduction band edges. We show that the energetically and spatially\nspin-polarized currents survive even in the fully ferromagnetic metallic state\nand heterojunction configurations. This suggests a simple yet ef-ficient scheme\nto achieve effectively smooth GNR edges and graphene-based spintronic de-vices.",
        "positive": "Dephasing in an Aharonov-Bohm interferometer containing a lateral double\n  quantum dot induced by coupling with a quantum dot charge sensor: We theoretically investigated the dephasing in an Aharonov-Bohm\ninterferometer containing a lateral double quantum dot induced by coupling with\na quantum dot charge sensor. We employed the interpolative 2nd-order\nperturbation theory to include the charge sensing Coulomb interaction. It is\nshown that the visibility of the Aharonov-Bohm oscillation of the linear\nconductance decreases monotonically as the sensing Coulomb interaction\nincreases. In particular, for a weak sensing interaction regime, the visibility\ndecreases parabolically, and it behaves linearly for a strong sensing\ninteraction regime."
    },
    {
        "anchor": "Enhanced Casimir effect for doped graphene: We analyze the Casimir interaction of doped graphene. To this end we derive a\nsimple expression for the finite temperature polarization tensor with a\nchemical potential. It is found that doping leads to a strong enhancement of\nthe Casimir force reaching almost $60\\%$ in quite realistic situations. This\nresult should be important for planning and interpreting the Casimir\nmeasurements, especially taking into account that the Casimir interaction of\nundoped graphene is rather weak.",
        "positive": "Orientation and strain modulated electronic structures in puckered\n  arsenene nanoribbons: Orthorhombic arsenene was recently predicted as an indirect bandgap\nsemiconductor. Here, we demonstrate that nanostructuring arsenene into\nnanoribbons can successfully transform the bandgap to be direct. It is found\nthat direct bandgaps hold for narrow armchair but wide zigzag nanoribbons,\nwhich is dominated by the competition between the in-plane and out-of-plane\nbondings. Moreover, straining the nanoribbons also induces a direct bandgap and\nsimultaneously modulates effectively the transport property. The gap energy is\nlargely enhanced by applying tensile strains to the armchair structures. In the\nzigzag ones, a tensile strain makes the effective mass of holes much higher\nwhile a compressive strain cause it much lower than that of electrons. Our\nresults are crutial to understand and engineer the electronic properties of two\ndimensional materials beyond the planar ones like graphene."
    },
    {
        "anchor": "Size dependent exciton g-factor in self-assembled InAs/InP quantum dots: We have studied the size dependence of the exciton g-factor in self-assembled\nInAs/InP quantum dots. Photoluminescence measurements on a large ensemble of\nthese dots indicate a multimodal height distribution. Cross-sectional Scanning\nTunneling Microscopy measurements have been performed and support the\ninterpretation of the macro photoluminescence spectra. More than 160 individual\nquantum dots have systematically been investigated by analyzing single dot\nmagneto-luminescence between 1200nm and 1600 nm. We demonstrate a strong\ndependence of the exciton g-factor on the height and diameter of the quantum\ndots, which eventually gives rise to a sign change of the g-factor. The\nobserved correlation between exciton g-factor and the size of the dots is in\ngood agreement with calculations. Moreover, we find a size dependent anisotropy\nsplitting of the exciton emission in zero magnetic field.",
        "positive": "\"New Zero-Resistance State\" in Heterojunctions: A Dynamical Effect: In this paper we discuss some general concepts regarding the recent\nexperiments of Mani et al and Zudov et al regarding the appearance of large\nresistance variations in the presence of a rf field. The possibility of\nnegative resistance is also discussed."
    },
    {
        "anchor": "Ratchet propagation of a magnetic domain wall in a single magnetic wire\n  with quantum interference: Quantum interference incorporating spatially asymmetric potential profiles is\nrealized experimentally to manipulate a magnetic domain wall (DW) into a single\nmultilayered wire whose spacer has a thickness gradient for generating\nasymmetrical interlayer exchange coupling from side to side. We demonstrate\nexperimentally how to guide a DW in a micron-scale ferromagnetic wire without\nreflection symmetry of the interlayer exchange coupling. This is the ratcheting\nof a DW in a form of ratchet potential using quantum interference. The\nexperimental results can be described well by numerical simulations considering\nspatially asymmetric potential profiles due to quantum interference.",
        "positive": "Finkel'stein nonlinear sigma model: interplay of disorder and\n  interaction in 2D electron systems: In this paper I briefly review recent theoretical results derived within the\nFinkel'stein nonlinear sigma model approach for description of 2D interacting\ndisordered electron systems. The examples include an electron system with two\nvalleys, electrons in a double quantum well, electrons on the surface of a\ntopological insulator, an electron system with superconducting correlations,\nand the integer quantum Hall effect."
    },
    {
        "anchor": "Semiclassical transport with Berry curvature: Chambers formula and\n  applications to systems with Fermi surface topological transitions: Starting with general semiclassical equations of motion for electrons in the\npresence of electric and magnetic fields, we extend the Chambers formula to\ninclude in addition to a magnetic field, time-dependent electric fields and\nbands with Berry curvature. We thereby compute the conductivity tensor\n${\\sigma}_{{\\alpha}{\\beta}}(B,{\\omega})$ in the presence of magnetic field for\nbands in two (2D) and three (3D) dimensions with Berry curvature. We focus then\non several applications to magnetotransport for metals with Fermi surface\ntopological transitions in 2D. In particular, we consider a rectangular lattice\nand a model related to overdoped graphene, to investigate the signatures of\ndifferent types of Fermi surface topological transitions in metals in the Hall\ncoefficient, Hall conductivity ${\\sigma}_{xy}$ and longitudinal conductivity\n${\\sigma}_{xx}$. The behavior of those quantities as a function of frequency,\nwhen the electric field is time dependent, is also investigated. As an example\nof non-zero Berry curvature, we study the magnetotransport of the Haldane model\nwithin this context. In addition, we provide the linear and nonlinear electric\ncurrent formula to order $E^2$.",
        "positive": "Anomalous sequence of quantum Hall liquids revealing tunable Lifshitz\n  transition in bilayer graphene: Fermi surface topology plays an important role in determining the electronic\nproperties of metals. In bulk metals, the Fermi energy is not easily tunable at\nthe energy scale needed for reaching conditions for the Lifshitz transition - a\nsingular point in the band structure where the connectivity of the Fermi\nsurface changes. Bilayer graphene is a unique system where both Fermi energy\nand the low-energy electron dispersion can be tuned using the interplay between\ntrigonal warping and a band gap opened by a transverse electric field. Here, we\ndrive the Lifshitz transition to experimentally controllable carrier densities\nby applying large transverse electric fields through a h-BN-encapsulated\nbilayer graphene structure, and detect it by measuring the degeneracies of\nLandau levels. These degeneracies are revealed by filling factor -3 and -6\nquantum Hall effect states of holes at low magnetic fields reflecting the\nexistence of three maxima on the top of the valence band dispersion. At high\nmagnetic fields all integer quantum Hall states are observed, indicating that\ndeeper in the valence band the constant energy contours are singly-connected.\nThe fact that we observe ferromagnetic quantum Hall states at odd-integer\nfilling factors testifies to the high quality of our sample, and this enables\nus to identify several phase transitions between correlated quantum Hall states\nat intermediate magnetic fields, in agreement with the calculated evolution of\nthe Landau level spectrum."
    },
    {
        "anchor": "Edge Configurational Effect on Band Gaps in Graphene Nanoribbons: In this Letter, we put forward a resolution to the prolonged ambiguity in\nenergy band gaps between theory and experiments of fabricated graphene\nnanoribbons (GNRs). Band structure calculations using density functional theory\nare performed on oxygen passivated GNRs supercells of customized edge\nconfigurations without disturbing the inherent sp2 hybridization of carbon\natoms. Direct band gaps are observed for both zigzag and armchair GNRs,\nconsistent with the experimental reports. In addition, band gap values of GNRs\nscattered about an average value curve for a given crystallographic orientation\nare correlated with their width on basis of the edge configurations elucidates\nthe band gaps in fabricated GNRs. We conclude that edge configurations of GNRs\nsignificantly contribute to band gap formation in addition to its width for a\ngiven crystallographic orientation, and would play a crucial role in band gap\nengineering of GNRs for future research works on fabrication of nanoelectronic\ndevices.",
        "positive": "Coupled exciton internal and center-of-mass motions in two-dimensional\n  semiconductors by a periodic electrostatic potential: We theoretically investigated the coupling between the exciton internal and\ncenter-of-mass motions in monolayer transition metal dichalcogenides subjected\nto a periodic electrostatic potential. The coupling leads to the emergence of\nmultiple absorption peaks in the exciton spectrum which are the hybridizations\nof 1s, 2s and 2p$\\pm$ Rydberg states with different center-of-mass momentums.\nThe energies and wave functions of hybrid states can be strongly modulated by\nvarying the profile of the periodic electrostatic potential, which well\nreproduces the recent experimental observations. Combined with the\nelectron-hole exchange interaction, non-degenerate valley-coherent bright\nexcitons can be realized by applying an in-plane electric field, with the\nvalley coherence determined by the field direction."
    },
    {
        "anchor": "Some symmetry properties of spin currents and spin polarizations in\n  multi-terminal mesoscopic spin-orbit coupled systems: We study theoretically some symmetry properties of spin currents and spin\npolarizations in multi-terminal mesoscopic spin-orbit coupled systems. Based on\na scattering wave function approach, we show rigorously that in the equilibrium\nstate no finite spin polarizations can exist in a multi-terminal mesoscopic\nspin-orbit coupled system (both in the leads and in the spin-orbit coupled\nregion) and also no finite equilibrium terminal spin currents can exist. By use\nof a typical two-terminal mesoscopic spin-orbit coupled system as the example,\nwe show explicitly that the nonequilibrium terminal spin currents in a\nmulti-terminal mesoscopic spin-orbit coupled system are non-conservative in\ngeneral. This non-conservation of terminal spin currents is not caused by the\nuse of an improper definition of spin current but is intrinsic to\nspin-dependent transports in mesoscopic spin-orbit coupled systems. We also\nshow that the nonequilibrium lateral edge spin accumulation induced by a\nlongitudinal charge current in a thin strip of \\textit{finite} length of a\ntwo-dimensional electronic system with intrinsic spin-orbit coupling may be\nnon-antisymmetric in general, which implies that some cautions may need to be\ntaken when attributing the occurrence of nonequilibrium lateral edge spin\naccumulation induced by a longitudinal charge current in such a system to an\nintrinsic spin Hall effect.",
        "positive": "Impact of junction length on supercurrent resilience against magnetic\n  field in InSb-Al nanowire Josephson junctions: Semiconducting nanowire Josephson junctions represent an attractive platform\nto investigate the anomalous Josephson effect and detect topological\nsuperconductivity by studying Josephson supercurrent. However, an external\nmagnetic field generally suppresses the supercurrent through hybrid nanowire\njunctions and significantly limits the field range in which the supercurrent\nphenomena can be studied. In this work, we investigate the impact of the length\nof InSb-Al nanowire Josephson junctions on the supercurrent resilience against\nmagnetic fields. We find that the critical parallel field of the supercurrent\ncan be considerably enhanced by reducing the junction length. Particularly, in\n30 nm-long junctions supercurrent can persist up to 1.3 T parallel field -\napproaching the critical field of the superconducting film. Furthermore, we\nembed such short junctions into a superconducting loop and obtain the\nsupercurrent interference at a parallel field of 1 T. Our findings are highly\nrelevant for multiple experiments on hybrid nanowires requiring a magnetic\nfield-resilient supercurrent."
    },
    {
        "anchor": "Size Dependence of Current Spin Polarization Through\n  Superconductor/Ferromagnet Nanocontacts: The spin polarization P of the transport current through the interface\nbetween superconducting Al and ferromagnetic Fe is determined by means of\nAndreev reflection at nanostructured point contacts. We observe a systematic\ndecrease of P with decreasing contact resistance. Our data provide evidence for\nthe reduction of P by spin-orbit scattering and thus establish a link between\ndensity-of-states and transport spin polarizations.",
        "positive": "Topological insulators in twisted transition metal dichalcogenide\n  homobilayers: We show that moir\\'e bands of twisted homobilayers can be topologically\nnontrivial, and illustrate the tendency by studying valence band states in $\\pm\nK$ valleys of twisted bilayer transition metal dichalcogenides, in particular,\nbilayer MoTe$_2$. Because of the large spin-orbit splitting at the monolayer\nvalence band maxima, the low energy valence states of the twisted bilayer\nMoTe$_2$ at $+K$ ($-K$) valley can be described using a two-band model with a\nlayer-pseudospin magnetic field $\\boldsymbol{\\Delta}(\\boldsymbol{r})$ that has\nthe moir\\'e period. We show that $\\boldsymbol{\\Delta}(\\boldsymbol{r})$ has a\ntopologically non-trivial skyrmion lattice texture in real space, and that the\ntopmost moir\\'e valence bands provide a realization of the Kane-Mele quantum\nspin-Hall model, i.e., the two-dimensional time-reversal-invariant topological\ninsulator. Because the bands narrow at small twist angles, a rich set of broken\nsymmetry insulating states can occur at integer numbers of electrons per\nmoir\\'e cell."
    },
    {
        "anchor": "Universal absorption of two-dimensional systems: We discuss the optical conductivity of several non-interacting\ntwo-dimensional (2D) semiconducting systems focusing on gapped Dirac and\nSchr\\\"odinger fermions as well as on a system mixing these two types. Close to\nthe band-gap, we can define a universal optical conductivity quantum of\n$\\sigma_0=\\frac{1}{16}\\frac{e^2}{\\hbar}$ for the pure systems. The effective\noptical conductivity then depends on the degeneracy factors $g_s$ (spin) and\n$g_v$ (valley) and on the curvature around the band-gap $\\nu$, i.e., it\ngenerally reads $\\sigma=g_sg_v\\nu\\sigma_0$. For a system composed of both types\nof carriers, the optical conductivity becomes non-universal.",
        "positive": "Coherent Population Trapping of an Electron Spin in a Single Negatively\n  Charged Quantum Dot: Coherent population trapping (CPT) refers to the steady-state trapping of\npopulation in a coherent superposition of two ground states which are coupled\nby coherent optical fields to an intermediate state in a three-level atomic\nsystem. Recently, CPT has been observed in an ensemble of donor bound spins in\nGaAs and in single nitrogen vacancy centers in diamond by using a fluorescence\ntechnique. Here we report the demonstration of CPT of an electron spin in a\nsingle quantum dot (QD) charged with one electron."
    },
    {
        "anchor": "Changing the Electronic Spectrum of a Quantum Dot by Adding Electrons: The temperature dependence of Coulomb blockade peak height correlation is\nused to investigate how adding electrons to a quantum dot alters or \"scrambles\"\nits electronic spectrum. Deviations from finite-temperature random matrix\ntheory with an unchanging spectrum indicate spectral scrambling after a small\nnumber of electrons are added. Enhanced peak-to-peak correlations at low\ntemperature are observed. Peak height statistics show similar behavior in\nseveral dot configurations despite significant differences in correlations.",
        "positive": "Parametric control of a superconducting flux qubit: Parametric control of a superconducting flux qubit has been achieved by using\ntwo-frequency microwave pulses. We have observed Rabi oscillations stemming\nfrom parametric transitions between the qubit states when the sum of the two\nmicrowave frequencies or the difference between them matches the qubit Larmor\nfrequency. We have also observed multi-photon Rabi oscillations corresponding\nto one- to four-photon resonances by applying single-frequency microwave\npulses. The parametric control demonstrated in this work widens the frequency\nrange of microwaves for controlling the qubit and offers a high quality testing\nground for exploring nonlinear quantum phenomena."
    },
    {
        "anchor": "On Choosing a Physically Meaningful Topological Classification for\n  Non-Hermitian Systems and the Issue of Diagonalizability: The topological classification of hermitian operators is solely determined by\nthe presence or absence of certain discrete symmetries. For non-hermitian\noperators we in addition need to specify the type of spectral gap. They come in\nthe flavor of a point gap or a line gap. Since the presence of a line gap\nimplies the existence of a point gap, there is usually more than one\nmathematical classification applicable to a physical system. That raises the\nquestion: which of these gap-type classifications is physically meaningful?\n  To decide this question, I propose a simple criterion, namely the choice of\nphysically relevant states. This generalizes the notion of Fermi projection\nthat plays a crucial role in the topological classification of fermionic\ncondensed matter systems, and enters as an auxiliary quantity in the bulk\nclassification of photonic and magnonic crystals. After that the classification\nis entirely algorithmic, the system's topology is encoded in (pairs of)\nprojections with symmetries and constraints. A crucial point in my\ninvestigation is the relevance of diagonalizability. Even for existing\ntopological classifications of non-hermitian systems diagonalizability needs to\nbe assumed to ensure that continuous deformations of the hamiltonian lead to\ncontinuous deformations of the spectra, projections and unitaries.",
        "positive": "Total Current Blockade in an Ultra-Cold Dipolar Quantum Wire: Cold atom systems offer a great potential for the future design of new\nmesoscopic quantum systems with properties that are fundamentally different\nfrom semiconductor nanostructures, such as quantum dots and quantum wires with\nelectrons. Here, we investigate the analog of a quantum wire using ultra-cold\nparticles, and find a new scenario for the quantum transport: Attractive\ninteractions may lead to a complete suppression of current in the low-bias\nrange, a total current blockade. We demonstrate this effect for the example of\nultra-cold quantum gases with dipolar interactions."
    },
    {
        "anchor": "Quantum transport in weakly coupled superlattices at low temperature: We report on the study of the electrical current flowing in weakly coupled\nsuperlattice (SL) structures under an applied electric field at very low\ntemperature, i.e. in the tunneling regime. This low temperature transport is\ncharacterized by an extremely low tunneling probability between adjacent wells.\nExperimentally, I(V) curves at low temperature display a striking feature, i.e\na plateau or null differential conductance. A theoretical model based on the\nevaluation of scattering rates is developed in order to understand this\nbehaviour, exploring the different scattering mechanisms in AlGaAs alloys. The\ndominant interaction in usual experimental conditions such as ours is found to\nbe the electron-ionized donors scattering. The existence of the plateau in the\nI(V) characteristics is physically explained by a competition between the\nelectric field localization of the Wannier-Stark electron states in the weakly\ncoupled quantum wells and the electric field assisted tunneling between\nadjacent wells. The influence of the doping concentration and profile as well\nas the presence of impurities inside the barrier are discussed.",
        "positive": "Addition energies of a Quantum Dot with harmonic electron-electron\n  interactions: We study a two dimensional electron system in a parabolic confining potential\nand constant magnetic field for the case of harmonic electron-electron\ninteraction. We present analytic results for the electrochemical potential\nversus magnetic field and discuss the effects of correlation in connection with\nthe addition energy of a Quantum Dot with few electrons."
    },
    {
        "anchor": "Disentangling Orbital Magnetic Susceptibility with Wannier Functions: Orbital magnetic susceptibility involves rich physics such as interband\neffects despite of its conceptual simplicity. In order to appreciate the rich\nphysics related to the orbital magnetic susceptibility, it is essential to\nderive a formula to decompose the susceptibility into the contributions from\neach band. Here, we propose a scheme to perform this decomposition using the\nmodified Wannier functions. The derived formula nicely decomposes the\nsusceptibility into intraband and interband contributions, and from the other\naspect, into itinerant and local contributions. The validity of the formula is\ntested in a couple of simple models. Interestingly, it is revealed that the\nquality of the decomposition depends on the degree of localization of the used\nWannier functions. The formula here complements another formula using Bloch\nfunctions, or the formula derived in the semiclassical theory, which deepens\nour understanding of the orbital magnetic susceptibility and may serve as a\nfoundation of a better computational method. The relationship to the Berry\ncurvature in the present scheme is also clarified.",
        "positive": "Spin relaxation in fluorinated single and bilayer graphene: We present a joint experiment-theory study on the role of fluorine adatoms in\nspin and momentum scattering of charge carriers in dilute fluorinated graphene\nand bilayer graphene. The experimental spin-flip and momentum scattering rates\nand their dependence on the density of fluorine and carrier doping are obtained\nthrough weak localization and conductivity measurements, respectively, and\nsuggest the role of fluorine as resonant magnetic impurities. For the estimated\nfluorine concentration of a few 100 ppm, the observed spin lifetimes are in the\nrange of 1-10\\,ps. Theoretically, we established tight-binding electronic\nstructures of fluorinated graphene and bilayer graphene by fitting to density\nfunctional supercell calculations and performed a comprehensive analysis of the\nspin-flip and momentum scattering rates within the same devices, aiming to\ndevelop a consistent description of both scattering channels. We find that\nresonant scattering in graphene is very sensitive to the precise position of\nthe resonance level, as well as to the magnitude of the exchange coupling\nbetween itinerant carriers and localized spins. The experimental data point to\nthe presence of weak spin-flip scatterers that, at the same time, relax the\nelectron momentum strongly, nearly preserving the electron-hole symmetry. Such\nscatterers would exhibit resonance energies much closer to the neutrality point\nthan what density functional theory predicts in the dilute limit. The inclusion\nof a magnetic moment on fluorine adatoms allowed us to qualitatively capture\nthe carrier density dependence of the experimental rates but predicts a greater\n(weaker) spin (momentum) relaxation rate than the measurements. We discuss\npossible scenarios that may be responsible for the discrepancies. Our\nsystematic study exposes the complexities involved in accurately capturing the\nbehavior of adatoms on graphene."
    },
    {
        "anchor": "Graphene bubbles with controllable curvature: Raised above the substrate and elastically deformed areas of graphene in the\nform of bubbles are found on different substrates. They come in a variety of\nshapes, including those which allow strong modification of the electronic\nproperties of graphene. We show that the shape of the bubble can be controlled\nby an external electric field. This effect can be used to make graphene-based\nadaptive focus lenses.",
        "positive": "Soft-clamped silicon nitride string resonators at millikelvin\n  temperatures: We demonstrate that soft-clamped silicon nitride strings with large aspect\nratio can be operated at \\si{\\milli\\kelvin} temperatures. The quality factors\n($Q$) of two measured devices show consistent dependency on the cryostat\ntemperature, with soft-clamped mechanical modes reaching $Q > 10^9$ at\n$46~\\mathrm{mK}$. For low optical readout power, $Q$ is found to saturate,\nindicating good thermalization between the sample and the stage it is mounted\non. Our best device exhibits a force sensitivity of\n$9.6~\\mathrm{zN}/\\sqrt{\\mathrm{Hz}}$ and a thermal decoherence time of\n$0.38~\\mathrm{s}$ which bode well for future applications such as\nnanomechanical force sensing and beyond."
    },
    {
        "anchor": "Observation of excited states in a graphene double quantum dot: We study a graphene double quantum dot in different coupling regimes. Despite\nthe strong capacitive coupling between the dots, the tunnel coupling is below\nthe experimental resolution. We observe additional structures inside the\nfinite-bias triangles, part of which can be attributed to electronic excited\ndot states, while others are probably due to modulations of the transmission of\nthe tunnel barriers connecting the system to source and drain leads.",
        "positive": "Phonon-induced enhancement of photon entanglement in quantum dot-cavity\n  systems: We report on simulations of the degree of polarization entanglement of photon\npairs simultaneously emitted from a quantum dot-cavity system that demand\nrevisiting the role of phonons. Since coherence is a fundamental precondition\nfor entanglement and phonons are known to be a major source of decoherence, it\nseems unavoidable that phonons can only degrade entanglement. In contrast, we\ndemonstrate that phonons can cause a degree of entanglement that even surpasses\nthe corresponding value for the phonon-free case. In particular, we consider\nthe situation of comparatively small biexciton binding energies and either\nfinite exciton or cavity mode splitting. In both cases, combinations of the\nsplitting and the dot-cavity coupling strength are found where the entanglement\nexhibits a nonmonotonic temperature dependence which enables entanglement above\nthe phonon-free level in a finite parameter range. This unusual behavior can be\nexplained by phonon-induced renormalizations of the dot-cavity coupling $g$ in\ncombination with a nonmonotonic dependence of the entanglement on $g$ that is\npresent already without phonons."
    },
    {
        "anchor": "Strain-induced collapse of Landau Levels in real Weyl semimetals: The collapse of Landau levels under an electric field perpendicular to the\nmagnetic field is one of the distinctive features of Dirac materials. So is the\ncoupling of lattice deformations to the electronic degrees of freedom in the\nform of gauge fields which allows the formation of pseudo-Landau levels from\nstrain. We analyze the collapse of Landau levels induced by strain on realistic\nWeyl semimetals hosting anisotropic, tilted Weyl cones in momentum space. We\nperform first-principles calculations, to establish the conditions on the\nexternal strain for the collapse of Landau levels in TaAs which can be\nexperimentally accessed.",
        "positive": "Magneto-Optical Quantum Switching in a System of Spinor Excitons: In this work we investigate magneto-optical properties of two-dimensional\nsemiconductor quantum-ring excitons with Rashba and Dresselhaus spin-orbit\ninteractions threaded by a magnetic flux perpendicular to the plane of the\nring. By calculating the excitonic Aharonov-Bohm spectrum, we study the Coulomb\nand spin-orbit effects on the Aharonov-Bohm features. From the light-matter\ninteractions of the excitons, we find that for scalar excitons, there are open\nchannels for spontaneous recombination resulting in a bright photoluminescence\nspectrum, whereas the forbidden recombination of dipolar excitons results in a\ndark photoluminescence spectrum. We investigate the generation of persistent\ncharge and spin currents. The exploration of spin orientations manifests that\nby adjusting the strength of the spin-orbit interactions, the exciton can be\nconstructed as a squeezed complex with specific spin polarization. Moreover, a\ncoherently moving dipolar exciton acquires a nontrivial dual Aharonov-Casher\nphase, creating the possibility to generate persistent dipole currents and spin\ndipole currents. Our study reveals that a manipulation of the spin-orbit\ninteractions provides a potential application for quantum-ring spinor excitons\nto be utilized in nano-scaled magneto-optical switches."
    },
    {
        "anchor": "Fermi liquid approach for superconducting Kondo problems: We present a Fermi liquid approach to superconducting Kondo problems\napplicable when the Kondo temperature is large compared to the superconducting\ngap. To illustrate the theory, we study the current-phase relation and the\nAndreev level spectrum for an Anderson impurity between two $s$-wave\nsuperconductors. In the particle-hole symmetric Kondo limit, we find a $4\\pi$\nperiodic Andreev spectrum. The $4\\pi$ periodicity persists under a small\nvoltage bias which however causes an asymmetric distortion of Andreev levels.\nThe latter distinguishes the present $4\\pi$ effect from the one in topological\nMajorana junctions.",
        "positive": "Electronic and magnetic properties of honeycomb zigzag nanoribbons in\n  the in-plane transverse electric field using Kane-Mele-Hubbard model: Using the Kane-Mele-Hubbard model in the unrestricted mean field\napproximation, the effect of spin-orbit coupling, as an intrinsic parameter,\nand an in-plane transverse electric field, as an external parameter, on the\nelectronic and magnetic properties of honeycomb zigzag nanoribbons are\ninvestigated in the presence of electron-electron interaction. Our calculations\nshow that each of these parameters has significant effects on the physical\nproperties of nanoribbons, and each of them independently transitions the\nnanoribbon from a magnetic to non-magnetic state. The process of change in some\naspect of physical properties, such as symmetry breaking, separation of spin up\nand spin down energy bands, reduction of magnetic order, change of electric\ndipole moment and spin current of nanoribbons, which are due to change of these\ntwo parameters are investigated. we will see that spin-orbit coupling in the\ncompetition with the transverse electric field determines the basic physical\nproperties of the nanoribbon. This research, can provide a better understanding\nof two types of topological and non-topological transitions. In addition, the\nseparation of spin-up and spin-down energy bands and their tuning by these\nparameters can be considered as a candidate for use in spintronic instruments."
    },
    {
        "anchor": "Angular momentum in the fractional quantum Hall effect: Suppose a classical electron is confined to move in the $xy$ plane under the\ninfluence of a constant magnetic field in the positive $z$ direction. It then\ntraverses a circular orbit with a fixed positive angular momentum $L_z$ with\nrespect to the center of its orbit. It is an underappreciated fact that the\nquantum wave functions of electrons in the ground state (the so-called lowest\nLandau level) have an azimuthal dependence $\\propto \\exp(-im\\phi) $ with $m\\geq\n0$, seemingly in contradiction with the classical electron having positive\nangular momentum. We show here that the gauge-independent meaning of that\nquantum number $m$ is not angular momentum, but that it quantizes the distance\nof the center of the electron's orbit from the origin, and that the physical\nangular momentum of the electron is positive and independent of $m$ in the\nlowest Landau levels. We note that some textbooks and some of the original\nliterature on the fractional quantum Hall effect do find wave functions that\nhave the seemingly correct azimuthal form $\\propto\\exp(+im\\phi)$ but only on\naccount of changing a sign (e.g., by confusing different conventions) somewhere\non the way to that result.",
        "positive": "Breaking the theoretical scaling limit for predicting quasi-particle\n  energies: The stochastic GW approach: We develop a formalism to calculate the quasi-particle energy within the GW\nmany-body perturbation correction to the density functional theory (DFT). The\noccupied and virtual orbitals of the Kohn-Sham (KS) Hamiltonian are replaced by\nstochastic orbitals used to evaluate the Green function, the polarization\npotential, and thereby the GW self-energy. The stochastic GW (sGW) relies on\nnovel theoretical concepts such as stochastic time-dependent Hartree\npropagation, stochastic matrix compression and spatial/temporal stochastic\ndecoupling techniques. Beyond the theoretical interest, the formalism enables\nlinear scaling GW calculations breaking the theoretical scaling limit for GW as\nwell as circumventing the need for energy cutoff approximations. We illustrate\nthe method for silicon nanocrystals of varying sizes with over 3000 electrons."
    },
    {
        "anchor": "From the Chern-Simons theory for the fractional quantum Hall effect to\n  the Luttinger model of its edges: The chiral Luttinger model for the edges of the fractional quantum Hall\neffect is obtained as the low energy limit of the Chern-Simons theory for the\ntwo dimensional system. In particular we recover the Kac-Moody algebra for the\ncreation and annihilation operators of the edge density waves and the\nbosonization formula for the electronic operator at the edge.",
        "positive": "Direct Observation of Long-range field-effect from gate tuning of\n  non-local conductivity: We report the observation of an unexpected, long-range field-effect in\nWTe$_2$ devices, leading to large gate-induced changes of the transport\nproperties of crystals much thicker than the electrostatic screening length.\nThe phenomenon --which manifests itself very differently from the conventional\nfield-effect-- originates from the non-local nature of transport in the devices\nthat are thinner than the carrier mean free path, because of the dominant role\nof surface scattering. We reproduce theoretically the gate dependence of the\nmeasured classical and quantum magneto-transport in all detail, and show that\nthe phenomenon is caused by the gate-tuning of the bulk carrier mobility by\nchanging the scattering at the surface. Our results demonstrate the possibility\nto gate tune the electronic properties deep in the interior of conducting\nmaterials, avoiding limitations imposed by electrostatic screening."
    },
    {
        "anchor": "Experimental determination of the absorption strength in absorbing\n  chaotic cavities: Due to the experimental necessity we present a formula to determine the\nabsorption strength by power losses inside a chaotic system (cavities, graphs,\nacoustic resonators, etc) when the antenna coupling, always present in\nexperimental measurements, is taken into account. This is done by calculating\nthe average of the absorption coefficient as a function of the absorption\nstrength and the coupling of the antenna to the system, in the one channel\ncase.",
        "positive": "Characterizing the attenuation of coaxial and rectangular\n  microwave-frequency waveguides at cryogenic temperatures: Low-loss waveguides are required for quantum communication at distances\nbeyond the chip-scale for any low-temperature solid-state implementation of\nquantum information processors. We measure and analyze the attenuation constant\nof commercially available microwave-frequency waveguides down to millikelvin\ntemperatures and single photon levels. More specifically, we characterize the\nfrequency-dependent loss of a range of coaxial and rectangular microwave\nwaveguides down to $0.005\\,\\rm{dB}/\\rm{m}$ using a resonant-cavity technique.\nWe study the loss tangent and relative permittivity of commonly used dielectric\nwaveguide materials by measurements of the internal quality factors and their\ncomparison with established loss models. The results of our characterization\nare relevant for accurately predicting the signal levels at the input of\ncryogenic devices, for reducing the loss in any detection chain, and for\nestimating the heat load induced by signal dissipation in cryogenic systems."
    },
    {
        "anchor": "Symmetry and Control of Spin-Scattering Processes in Two-Dimensional\n  Transition Metal Dichalcogenides: Transition metal dichalcogenides (TMDs) combine interesting optical and\nspintronic properties in an atomically-thin material, where the light\npolarization can be used to control the spin and valley degrees-of-freedom for\nthe development of novel opto-spintronic devices. These promising properties\nemerge due to their large spin-orbit coupling in combination with their crystal\nsymmetries. Here, we provide simple symmetry arguments in a group-theory\napproach to unveil the symmetry-allowed spin scattering mechanisms, and\nindicate how one can use these concepts towards an external control of the spin\nlifetime. We perform this analysis for both monolayer (inversion asymmetric)\nand bilayer (inversion symmetric) crystals, indicating the different mechanisms\nthat play a role in these systems. We show that, in monolayer TMDs, electrons\nand holes transform fundamentally differently -- leading to distinct\nspin-scattering processes. We find that one of the electronic states in the\nconduction band is partially protected by time-reversal symmetry, indicating a\nlonger spin lifetime for that state. In bilayer and bulk TMDs, a hidden\nspin-polarization can exist within each layer despite the presence of global\ninversion symmetry. We show that this feature enables control of the interlayer\nspin-flipping scattering processes via an out-of-plane electric field,\nproviding a mechanism for electrical control of the spin lifetime.",
        "positive": "Transverse anisotropy effects on spin-resolved transport through\n  large-spin molecules: The transport properties of a large-spin molecule strongly coupled to\nferromagnetic leads in the presence of transverse magnetic anisotropy are\nstudied theoretically. The relevant spectral functions, linear-response\nconductance and the tunnel magnetoresistance are calculated by means of the\nnumerical renormalization group method. We study the dependence of transport\ncharacteristics on orbital level position, uniaxial and transverse\nanisotropies, external magnetic field and temperature. It is shown that while\nuniaxial magnetic anisotropy leads to the suppression of the Kondo effect,\nfinite transverse anisotropy can restore the Kondo resonance. The effect of\nKondo peak restoration strongly depends on the magnetic configuration of the\ndevice and leads to nontrivial behavior of the tunnel magnetoresistance. We\nshow that the temperature dependence of the conductance at points where the\nrestoration of the Kondo effect occurs is universal and shows a scaling typical\nfor usual spin-one-half Kondo effect."
    },
    {
        "anchor": "Ferromagnetic resonant tunneling diodes as spin polarimeters and\n  polarizers: A method for measuring the degree of spin polarization of magnetic materials\nbased on spin-dependent resonant tunneling is proposed. The device we consider\nis a ballistic double-barrier resonant structure consisting of a ferromagnetic\nlayer embedded between two insulating barriers. A simple procedure, based on a\ndetailed analysis of the differential conductance, allows to accurately\ndetermine the polarization of the ferromagnet. The spin-filtering character of\nsuch a system is furthermore addressed. We show that a 100% spin selectivity\ncan be achieved under appropriate conditions. This approach is believed to be\nwell suited for the investigation of diluted magnetic semiconductor\nheterostructures.",
        "positive": "Time-dependent theory of non-linear response and current fluctuations: A general non-linear response theory is derived for an arbitrary\ntime-dependent Hamiltonian, not necessarily obeying time-reversal symmetry.\nThis allows us to obtain a greatly generalized Kubo type formula. Applied to a\nmesoscopic system with any type of interactions, and coupled to multiple probes\nand gates with arbitrarily time-dependent voltages, we derive\ncurrent-conserving differential conductance and current fluctuation matrices\nobeying a generalized Fluctuation-Dissipation Theorem. This relation provides a\ncommon explanation for asymmetries of the excess noise in several non-linear\nmesoscopic systems, as well as of its surprising negative sign."
    },
    {
        "anchor": "Time-dependent magneto-transport in a driven graphene spin valve: Based on the time-dependent nonequilibrium Green's function method we\ninvestigate theoretically the time and spin-dependent transport through a\ngraphene layer upon the application of a static bias voltage to the electrodes\nand a time-alternating gate voltage to graphene. The electrodes are magnetic\nwith arbitrary mutual orientations of their magnetizations. We find features in\nthe current that are governed by an interplay of the strength of the\nalternating field and the Dirac point in graphene: The influence of a weak\nalternating field on the zero bias conductance is strongly suppressed by the\nzero density of state at the Dirac point. In contrast, for a strong amplitude\nof the alternating field the current is dominated by several resonant peaks, in\nparticular a marked peak appears at zero bias. This subtle competition results\nin a transition of the tunnel magnetoresistance from a broad peak to a sharp\ndip at a zero bias voltage applied to the electrodes. The dip amplitude can be\nmanipulated by tuning the ac field frequency.",
        "positive": "The Hall conductance, topological quantum phase transition and the\n  Diophantine equation on honeycomb lattice: We consider a tight-binding model with the nearest neighbour hopping\nintegrals on the honeycomb lattice in a magnetic field. Assuming one of the\nthree hopping integrals, which we denote t_a, can take a different value from\nthe two others, we study quantum phase structures controlled by the anisotropy\nof the honeycomb lattice.For weak and strong t_a regions, respectively, the\nHall conductances are calculated algebraically by using the Diophantine\nequation. Except for a few specific gaps, we completely determine the Hall\nconductances in these two regions including those for subband gaps. In a weak\nmagnetic field, it is found that the weak t_a region shows the unconventional\nquantization of the Hall conductance, \\sigma_{xy}=-(e^2/h)(2n+1), (n=0,\\pm\n1,\\pm 2,...), near the half-filling, while the strong t_a region shows only the\nconventional one, \\sigma_{xy}=-(e^2/h)n,(n=0,1,2,...). From topological nature\nof the Hall conductance, the existence of gap closing points and quantum phase\ntransitions in the intermediate t_a region are concluded. We also study\nnumerically the quantum phase structure in detail, and find that even when\nt_a=1, namely in graphene case, the system is in the weak t_a phase except when\nthe Fermi energy is located near the van Hove singularity or the lower and\nupper edges of the spectrum."
    },
    {
        "anchor": "The Localization Dichotomy for gapped periodic quantum systems: We investigate the localization properties of gapped periodic quantum\nsystems, modeled by a periodic or covariant family of projectors, as e.g. the\northogonal projectors on the occupied orbitals at fixed crystal momentum for a\ngas of non-interacting electrons. We prove a general localization dichotomy for\ndimension $d\\leq 3$: either the system is topologically trivial i.e. all the\nChern numbers vanish, or any arbitrary choice of composite Wannier functions\nyields an infinite expectation value for the squared position operator.\nEquivalently, in the topologically non-trivial phase, the localization\nfunctional introduced by Marzari and Vanderbilt diverges, as already noticed in\nthe case of the Haldane model. Our result is formulated by using only the\nrelevant symmetries of the system, and it is thus largely model-independent.\nPossible applications include both tight-binding and continuous models of\ncrystalline solids, cold gases in optical lattices as well as flat band\nsuperconductivity.",
        "positive": "Disorder effects on Majorana zero modes: Kitaev chain versus\n  semiconductor nanowire: Majorana zero modes in a superconductor-semiconductor nanowire have been\nextensively studied during the past decade. Disorder remains a serious problem,\npreventing the definitive observation of topological Majorana bound states.\nThus, it is worthwhile to revisit the simple model, the Kitaev chain, and study\nthe effects of weak and strong disorder on the Kitaev chain. By comparing the\nrole of disorder in a Kitaev chain with that in a nanowire, we find that\ndisorder affects both systems but in a nonuniversal manner. In general,\ndisorder has a much stronger effect on the nanowire than the Kitaev chain,\nparticularly for weak to intermediate disorder. For strong disorder, both the\nKitaev chain and nanowire manifest random featureless behavior due to universal\nAnderson localization. Only the vanishing and strong disorder regimes are thus\nuniversal, manifesting respectively topological superconductivity and Anderson\nlocalization, but the experimentally relevant intermediate disorder regime is\nnonuniversal with the details dependent on the disorder realization in the\nsystem."
    },
    {
        "anchor": "Probing miniband structure and Hofstadter butterfly in gated graphene\n  superlattices via magnetotransport: The presence of periodic modulation in graphene leads to a reconstruction of\nthe band structure and formation of minibands. In an external uniform magnetic\nfield, a fractal energy spectrum called Hofstadter butterfly is formed.\nParticularly interesting in this regard are superlattices with tunable\nmodulation strength, such as electrostatically induced ones in graphene. We\nperform quantum transport modeling in gate-induced square two-dimensional\nsuperlattice in graphene and investigate the relation to the details of the\nband structure. At low magnetic field the dynamics of carriers reflects the\nsemi-classical orbits which depend on the mini band structure. We theoretically\nmodel transverse magnetic focusing, a ballistic transport technique by means of\nwhich we investigate the minibands, their extent and carrier type. We find a\ngood agreement between the focusing spectra and the mini band structures\nobtained from the continuum model, proving usefulness of this technique.\n%positions of van Hove singularities at high magnetic field the calculated\nfour-probe resistance fit the Hofstadter butterfly spectrum obtained for our\nsuperlattice. Our quantum transport modeling provides an insight into the mini\nband structures, and can be applied to other superlattice geometries.",
        "positive": "A general solution to the Schr\u00f6dinger-Poission equation for charged\n  hard wall: Application to potential profile of an AlN/GaN barrier structure: A general, system-independent formulation of the parabolic\nSchr\\\"odinger-Poisson equation is presented for a charged hard wall in the\nlimit of complete screening by the ground state. It is solved numerically using\niteration and asymptotic-boundary conditions. The solution gives a simple\nrelation between the band bending and charge density at an interface. I further\ndevelop approximative analytical forms for the potential and wave function,\nbased on properties of the exact solution. Specific tests of the validity of\nthe assumptions leading to the general solution are made. The assumption of\ncomplete screening by the ground state is found be a limitation; however, the\ngeneral solution still provides a fair approximate account of the potential\nwhen the bulk is doped. The general solution is further used in a simple model\nfor the potential profile of an AlN/GaN barrier, and gives an approximation\nwhich compares well with the solution of the full Schr\\\"odinger-Poisson\nequation."
    },
    {
        "anchor": "Higher-order Weyl superconductors with anisotropic Weyl-point\n  connectivity: Weyl superconductors feature Weyl points at zero energy in the\nthree-dimensional (3D) Brillouin zone and arc states that connect the\nprojections of these Weyl points on the surface. We report that higher-order\nWeyl superconductors can be realized in odd-parity topological superconductors\nwith time-reversal symmetry being broken by periodic driving. Different from\nconventional Weyl points, the higher-order Weyl points in the bulk separate 2D\nfirst- and second-order topological phases, while on the surface, their\nprojections are connected not only by conventional surface Majorana arcs, but\nalso by hinge Majorana arcs. We show that the Weyl-point connectivity via\nMajorana arcs is largely enriched by the underlying higher-order topology and\nbecomes anisotropic with respect to surface orientations. We identify the\nanisotropic Weyl-point connectivity as a characteristic feature of higher-order\nWeyl materials. As each 2D subsystem can be singled out by fixing the periodic\ndriving, we propose how the Majorana zero modes in the 2D higher-order\ntopological phases can be detected and manipulated in experiments.",
        "positive": "High Frequency EPR Spectra of [Fe8O2(OH)12(tacn)6]Br8. A Critical\n  Appraisal of the Barrier for the Reorientation of the Magnetization in Single\n  Molecule Magnets: A detailed multifrequency high field - high frequency EPR (95-285 GHz) study\nhas been performed on the single-molecule magnet of formula\n  [Fe8O2(OH)12(tacn)6]Br8 9H2O, where tacn=1,4,7-triazacyclononane.\nPolycrystalline powder spectra have allowed estimating the zero field splitting\nparameters up to the fourth order terms.\n  The single crystal spectra have provided the principal directions of the\nmagnetic anisotropy of the cluster. These results have been compared to an\nevaluation of the intra-cluster dipolar contribution to the magnetic\nanisotropy, suggesting that single ion anisotropy is mainly contributing to the\nmagnetic anisotropy.\n  The role of the transverse magnetic anisotropy in determining the height of\nthe barrier for the reversal of the magnetization is also discussed."
    },
    {
        "anchor": "Non-left-handed transmission and bianisotropic effect in a [pi]-shaped\n  metallic metamaterials: A [pi]-shaped metallic metamaterial (geometrically, a combination medium of\nC-shaped resonators and continuous wires) is proposed to numerically\ninvestigate its transmission band near the resonant frequency, where otherwise\nit should be a negative-permeability (or negative-permittivity) stop band if\neither the C-shaped or continuous-wire constituent is separately considered.\nHowever, in contrast to the left-handed materials (LHMs)composed of split-ring\nresonators and wires as well as other metallic LHMs, this resonant transmission\nis a non-left-handed one as a result of the intrinsic bianisotropic effect\nattributed to the electrically asymmetric configuration of this [pi]-shaped\nmetamaterial.",
        "positive": "Electron conduction within Landau level tails of medium-mobility GaAs /\n  AlGaAs heterostructures: The temperature dependence of both components of the resistivity tensor\n$\\varrho_{xx}(T)$ and $\\varrho_{xy}(T)$ has been studied at T $\\geq$ 4.2 K\nwithin IQHE plateaux around filling factors \\nu=2 and \\nu=4 of medium-\n-mobility GaAs/AlGaAs heterostructures. In the middle of the mobility gap\nstandard activated conductivity has been found with activation energies $\\Delta\n$ scaling well with $\\hbar\\omega_{c} / 2$ . At filling factors slightly below\n$\\nu$=2 another contribution adds to the activated conductivity at T $\\leq$ 12\nK. This additional contribution can be further enhanced at higher mesuring d.c.\ncurrents.We suggest, that it arises due to enhanced electric field assisted\ntunneling across potential barriers separating localized states within the bulk\nof the sample.This effect contributes to the backscattering across the sample\nleading to an enhanced longitudinal conductivity. The additional contribution\nto $\\sigma_{xx}(T)$ can be reasonably well fitted to the formula for the\nvariable range hopping in strong magnetic fields indicating that the hopping\ncan persist even at temperatures well above 4.2K."
    },
    {
        "anchor": "Evidence of quantum Griffiths phase in Ni_{1-x}V_x nanoalloys: Metallic Ni$_{1-x}$V$_x$ alloys are known to exhibit a ferromagnetic to\nparamagnetic disordered quantum phase transition (QPT) at the critical\nconcentration $x_c \\sim$ 0.114 in bulk. Such a QPT is accompanied by a quantum\nGriffiths phase (QGP), the physical observables in which follow non-universal\npower-law temperature dependences, in a finite temperature range on the\nparamagnetic side of the transition. In the present work, we explore the\noccurrence of QGP in nanoparticles of this alloy system. Nanoalloys with $x$ in\nthe neighbourhood of $x_c$ and mean diameter 18-33 nm were prepared by a\nchemical reflux method. Following a few microscopic and spectroscopic studies\nto determine the sizes, compositions and phases, dc magnetization measurements\nwere also performed to seek out any signature of QGP in the nanoalloys. A\nparamagnetic-like increase of magnetization is observed to emerge below an\n$x$-dependent transition temperature $\\rm{T_P} (\\it{x})$ within the blocked\nferromagnetic state of the nanoparticles, and is corroborated by a peak at\n$\\rm{T_P} (\\it{x})$ in the temperature dependence of resistivity. The magnetic\nsusceptibility in this emergent phase follows a non-Curie power-law temperature\ndependence below 10 K for $0.09 \\leq x \\leq 0.14$, indicating the presence of a\nQGP in the nanoparticles within these temperature and composition ranges.",
        "positive": "Moir\u00e9 phonons in graphene/hexagonal boron nitride moir\u00e9 superlattice: We theoretically study in-plane acoustic phonons of graphene/hexagonal boron\nnitride moir\\'e superlattice by using a continuum model. We demonstrate that\nthe original phonon bands of individual layers are strongly hybridized and\nreconstructed into moir\\'e phonon bands consisting of dispersive bands and flat\nbands. The phonon band structure can be effectively described by a spring-mass\nnetwork model to simulate the motion of moir\\'e domain walls, where the\nflat-band modes are interpreted as vibrations of independent, decoupled\nstrings. We also show that the moir\\'e phonon has angular momentum due to the\ninversion symmetry breaking by hBN, with high amplitudes concentrated near\nnarrow gap region. Finally, we apply the same approach to twisted bilayer\ngraphene, and we find a notable difference between the origins of the flat-band\nmodes in G/hBN and TBG, reflecting distinct geometric structures of domain\npattern."
    },
    {
        "anchor": "Theory of spin accumulation and spin transfer torque in a magnetic\n  domain wall: We study spin accumulation and spin transfer torque in a domain wall by\nsolving the Boltzmann equation with a diffusion approximation. We obtained the\nanalytical expressions of spin accumulation and spin transfer torque. Both the\nadiabatic and the non-adiabatic components of the spin transfer torque\noscillate with the thickness of the domain wall. We show that the oscillation\nplays a dominant role in the non-adiabatic torque when the domain wall\nthickness is less than the spin-flip length, which is defined by the product of\nthe Fermi velocity and the spin-flip scattering time.",
        "positive": "Drag effects in the system of electrons and microcavity polaritons: The theory of the drag effects in the system of spatially separated electrons\nand excitons in coupled quantum wells (QW) embedded in an optical microcavity\nis developed. It is shown that at low temperature an electron current induces\nthe (normal component) polariton flow, therefore, a transport of photons along\nthe cavity. However, the electron current dragged by the polariton flow is\nstrongly suppressed below polariton superfluid transition temperature and\nhence, the strong suppression of the induced electron current indicates the\nsuperfluidity of polaritons. Therefore, the transport properties of polaritons\ncan be investigated by measuring the current or voltage in the electron\nsubsystem. At high temperatures we study the exciton-electron drag effects. At\nhigh temperatures regime, from one hand, the existence of the electric current\nin an electron QW induces the exciton flow in the other QW, from the other\nhand, the electron current in one QW induces the exciton flow in the other QW\nvia the drag of excitons by the electrons. The drag coefficients for the\npolariton-electron systems are calculated and analyzed. We discuss the possible\nexperimental observation of the drag effects in the system of electrons and\nmicrocavity polaritons, that also allow to observe the cavity polaritons\nsuperfluidity."
    },
    {
        "anchor": "Theory of Exciton Energy Transfer in Carbon Nanotube Composites: We compute the exciton transfer (ET) rate between semiconducting single-wall\ncarbon nanotubes (SWNTs). We show that the main reasons for the wide range of\nmeasured ET rates reported in the literature are 1) exciton confinement in\nlocal quantum wells stemming from disorder in the environment and 2) exciton\nthermalization between dark and bright states due to intratube scattering. The\nSWNT excitonic states are calculated by solving the Bethe-Salpeter equation\nusing tight-binding basis functions. The ET rates due to intertube Coulomb\ninteraction are computed via Fermi's golden rule. In pristine samples, the ET\nrate between parallel (bundled) SWNTs of similar chirality is very high ($\\sim\n10^{14}\\;\\text{s}^{-1}$) while the ET rate for dissimilar or nonparallel tubes\nis considerably lower ($\\sim 10^{12}\\;\\text{s}^{-1}$). Exciton confinement\nreduces the ET rate between same-chirality parallel SWNTs by two orders of\nmagnitude, but has little effect otherwise. Consequently, the ET rate in most\nmeasurements will be on the order of $ 10^{12}\\;\\text{s}^{-1}$, regardless of\nthe tube relative orientation or chirality. Exciton thermalization between\nbright and dark states further reduces the ET rate to about\n$10^{11}\\;\\text{s}^{-1}$. The ET rate also increases with increasing\ntemperature and decreases with increasing dielectric constant of the\nsurrounding medium.",
        "positive": "Majorana bound states and zero-bias conductance peaks in\n  superconductor/semiconductor nanowire devices: Theoretical research suggests a emergence of the Majorana bound states at the\nends of the nanowires. Experimental verifications of said concept has already\nbeen executed, e.g., in superconductor/semiconductor nanowire devices where\ninterplay between superconducting gap, spin-orbit coupling and external\nmagnetic field allows for creation of zero-energy bound states. Recent\nexperiments propose a topological phase diagram by local modification of the\neffective chemical potential. We discuss this possibility, using a model of\nexperimental system in form of semi-infinite S/N junction. We calculate the\nzero--bias differential conductance $G$ in the case of the homogeneous system,\nas well as in the presence of the gate voltage. Relation between conductance\nand the effective gap in the system is investigated. We show that $G$ can\nreproduce the topological phase diagram in magnetic field vs. gate voltage\nspace of parameters."
    },
    {
        "anchor": "Microwave Spin-Pumping from an Antiferromagnet FeBO3: Recently, canted antiferromagnets offer great potential for fundamental\nresearch and applications due to their unique properties. The presence of the\nDzyaloshinskii-Moriya interaction leads to the existence of a weak\nferromagnetic moment at room temperature. We study both theoretically and\nexperimentally microwave spin pumping by the quasi-ferromagnetic mode from a\ncanted easy plane antiferromagnet with weak ferromagnetism FeBO3. The\nconversion of a microwave signal into the constant voltage is realized using\nthe inverse spin Hall effect in an iron borate/heavy metal heterostructure. We\nuse an additional bias magnetic field to selectively tune the resonance\nfrequency of such a microwave detector over a wide range up to 43.5 GHz with\npotential sensitivity near 2.5 microV/W. We confirm the pure spin current\nnature by changing polarity of the detected via inverse spin Hall effect\nvoltage by switching the direction of the bias magnetic field. We believe that\nour results will be useful for the development of highly tunable, portable and\nsensitive microwave antiferromagnet-based functional devices.",
        "positive": "Polarization-sensitive absorption of THz radiation by interacting\n  electrons in chirally stacked multilayer graphene: We show that opacity of a clean multilayer graphene flake depends on the\nhelicity of the circular polarized electromagnetic radiation. The effect can be\nunderstood in terms of the pseudospin selection rules for the interband optical\ntransitions in the presence of exchange electron-electron interactions which\nalter the pseudospin texture in momentum space. The interactions described\nwithin a semi-analytical Hartree--Fock approach lead to the formation of the\ntopologically different broken--symmetry states characterized by Chern numbers\nand zero-field anomalous Hall conductivities."
    },
    {
        "anchor": "Gain in quantum cascade lasers and superlattices: A quantum transport\n  theory: Gain in current-driven semiconductor heterostructure devices is calculated\nwithin the theory of nonequilibrium Green functions. In order to treat the\nnonequilibrium distribution self-consistently the full two-time structure of\nthe theory is employed without relying on any sort of Kadanoff-Baym Ansatz. The\nresults are independent of the choice of the electromagnetic field if the\nvariation of the self-energy is taken into account. Excellent quantitative\nagreement is obtained with the experimental gain spectrum of a quantum cascade\nlaser. Calculations for semiconductor superlattices show that the simple 2-time\nminiband transport model gives reliable results for large miniband widths at\nroom temperature",
        "positive": "Exchange and the Coulomb blockade: Peak height statistics in quantum\n  dots: We study the effect of the exchange interaction on the Coulomb blockade peak\nheight statistics in chaotic quantum dots. Because exchange reduces the level\nrepulsion in the many body spectrum, it strongly affects the fluctuations of\nthe peak conductance at finite temperature. We find that including exchange\nsubstantially improves the description of the experimental data. Moreover, it\nprovides further evidence of the presence of high spin states (S>1) in such\nsystems."
    },
    {
        "anchor": "Size-dependent melting: Numerical calculations of the phonon spectrum: In order to clarify the relationship between the phonon spectra of\nnanoparticles and their melting temperature, we studied in detail the\nsize-dependent low energy vibration modes. A minimum model with atoms on a\nlattice and harmonic potentials for neighboring atoms is used to reveal a\ngeneral behavior. By calculating the phonon spectra for a series of\nnanoparticles of two lattice types in different sizes, we found that density of\nlow energy modes increases as the size of nanoparticles decreases, and this\ndensity increasing causes decreasing of melting temperature. Size-dependent\nbehavior of the phonon spectra accounts for typical properties of\nsurface-premelting and irregular melting temperature on fine scales. These\nresults show that our minimum model captures main physics of nanoparticles.\nTherefore, more physical characteristics for nanoparticles of certain types can\nbe given by phonons and microscopic potential models.",
        "positive": "Gap engineering and wave function symmetry in C and BN armchair\n  nanoribbons: Many are the ways of engineering the band gap of nanoribbons including\napplication of stress, electric field and functionalization of the edges. In\nthis article, we investigate separately the effects of these methods on\narmchair graphene and boron nitride nanoribbons. By means of density functional\ntheory calculations, we show that, despite their similar structure, the two\nmaterials respond in opposite ways to these stimuli. By treating them as\nperturbations of a heteroatomic ladder model based on the tight-binding\nformalism, we connect the two behaviours to the different symmetries of the top\nvalence and bottom conduction wave functions. These results indicate that\nopposite and complementary strategies are preferable to engineer the gapwidth\nof armchair graphene and boron nitride nanoribbons."
    },
    {
        "anchor": "Regulating spin dynamics in magnetic nanomaterials: Magnetic nanomaterials can be used in the construction of devices for\ninformation processing and memory storage. For this purpose, they have to enjoy\ntwo contradictory properties, from one side being able of keeping for long time\nmagnetization frozen, hence information stored, and from the other side\nallowing for quick change of magnetization required for fast erasing of memory\nand rewriting new information. Methods of resolving this dilemma are suggested\nbased on triggering resonance, dynamic resonance tuning, and on quadratic\nZeeman effect. These methods make it possible to realize effective regulation\nof spin dynamics in such materials as magnetic nanomolecules and magnetic\nnanoclusters.",
        "positive": "The quantum scattering time and its implications on scattering sources\n  in graphene (Supplementary): Supplementary Information Content:\n  1. Sample preparation;\n  2. Background subtraction of Shubnikov-de Haas (SdH) oscillations;\n  3. The effect of density inhomogeneity on the quantum scattering time tau_q;\n  4. Determine the concentration of charged impurity n_imp at a distance z;\n  5. Scattering from charges in the bulk of the SiO_2 substrate."
    },
    {
        "anchor": "Skyrmion Helicity: Quantization and Quantum Tunneling Effects: We derive the quantization of magnetic helicity in the solid-state and\ndemonstrate tunable macroscopic quantum tunneling, coherence, and oscillation\nfor a skyrmion spin texture stabilized in frustrated magnets. We also discuss\nthe parameter space for the experimental realization of quantum effects.\nTypically, for a skyrmion of 5 nm radius, quantum tunneling between two\nmacroscopic states with distinct helicities occurs with an inverse escape rate\nwithin seconds below 100 mK, and an energy splitting in the MHz regime.\nFeasibility of quantum tunneling of an ensemble of magnetic spins inspires new\nplatforms for quantum operations utilizing topologically protected chiral spin\nconfigurations.",
        "positive": "Plasmon-enhanced near-field chirality in twisted van der Waals\n  heterostructures: It is shown that chiral plasmons, characterized by a longitudinal magnetic\nmoment accompanying the longitudinal charge plasmon, lead to electromagnetic\nnear-fields that are also chiral. For twisted bilayer graphene, we estimate\nthat the near field chirality of screened plasmons can be several orders of\nmagnitude larger than that of the related circularly polarized light. The\nchirality also manifests itself in a deflection angle that is formed between\nthe direction of the plasmon propagation and its Poynting vector. Twisted van\nder Waals heterostructures might thus provide a novel platform to promote\nenantiomer-selective physio-chemical processes in chiral molecules without the\napplication of a magnetic field or external nano-patterning that break\ntime-reversal, mirror plane or inversion symmetry, respectively."
    },
    {
        "anchor": "Berry's Phase and Renormalization of Applied Oscillating Electric Fields\n  by Topological Quasi-Particles: We introduce the concept of Berry's phase in Josephson junctions and consider\nhow this geometric phase arises due to applied oscillating electric fields. The\nelectromagnetic field excites topological quasi-particles from the junction\nvacuum which affect Cooper-pair tunneling across the Josephson junction\nbarrier. A finite Berry's phase can be detected by its renormalization of the\nelectric field amplitude absorbed by the junction. This has implications for\nthe designing of accurate Josephson junction microwave detectors.",
        "positive": "Magnetic Field Induced Insulating Phases at Large $r_s$: Exploring a backgated low density two-dimensional hole sample in the large\n$r_s$ regime we found a surprisingly rich phase diagram. At the highest\ndensities, beside the $\\nu=1/3$, 2/3, and 2/5 fractional quantum Hall states,\nwe observe both of the previously reported high field insulating and reentrant\ninsulating phases. As the density is lowered, the reentrant insulating phase\ninitially strengthens, then it unexpectedly starts weakening until it\ncompletely dissapears. At the lowest densities the terminal quantum Hall state\nmoves from $\\nu=1/3$ to $\\nu=1$. The intricate behavior of the insulating\nphases can be explained by a non-monotonic melting line in the $\\nu$-$r_s$\nphase space."
    },
    {
        "anchor": "Charge transfer and asymmetric coupling of MoSe$_2$ valleys to the\n  magnetic order of CrSBr: Van der Waals (vdW) heterostructures composed of two-dimensional (2D)\ntransition metal dichalcogenides (TMD) and vdW magnetic materials offer an\nintriguing platform to functionalize valley and excitonic properties in\nnon-magnetic TMDs. Here, we report magneto-photoluminescence (PL)\ninvestigations of monolayer (ML) MoSe$_2$ on the layered A-type\nantiferromagnetic (AFM) semiconductor CrSBr under different magnetic field\norientations. Our results reveal a clear influence of the CrSBr magnetic order\non the optical properties of MoSe$_2$, such as an anomalous linear-polarization\ndependence, changes of the exciton/trion energies, a magnetic-field dependence\nof the PL intensities, and a valley $g$-factor with signatures of an asymmetric\nmagnetic proximity interaction. Furthermore, first principles calculations\nsuggest that MoSe$_2$/CrSBr forms a broken-gap (type-III) band alignment,\nfacilitating charge transfer processes. The work establishes that\nantiferromagnetic-nonmagnetic interfaces can be used to control the valley and\nexcitonic properties of TMDs, relevant for the development of opto-spintronics\ndevices.",
        "positive": "Singular perturbations approach to localized surface-plasmon resonance:\n  Nearly touching metal nanospheres: Metallic nano-structures characterised by multiple geometric length scales\nsupport low-frequency surface-plasmon modes, which enable strong light\nlocalization and field enhancement. We suggest studying such configurations\nusing singular perturbation methods, and demonstrate the efficacy of this\napproach by considering, in the quasi-static limit, a pair of nearly touching\nmetallic nano-spheres subjected to an incident electromagnetic wave polarized\nwith the electric field along the line of sphere centers. Rather than\nattempting an exact analytical solution, we construct the pertinent\n(longitudinal) eigen-modes by matching relatively simple asymptotic expansions\nvalid in overlapping spatial domains. We thereby arrive at an effective\nboundary eigenvalue problem in a half-space representing the metal region in\nthe vicinity of the gap. Coupling with the gap field gives rise to a mixed-type\nboundary condition with varying coefficients, whereas coupling with the\nparticle-scale field enters through an integral eigenvalue selection rule\ninvolving the electrostatic capacitance of the configuration. By solving the\nreduced problem we obtain accurate closed-form expressions for the resonance\nvalues of the metal dielectric function. Furthermore, together with an\nenergy-like integral relation, the latter eigen-solutions yield also\nclosed-form approximations for the induced-dipole moment and gap-field\nenhancement under resonance. We demonstrate agreement between the asymptotic\nformulas and a semi-numerical computation. The analysis, underpinned by\nasymptotic scaling arguments, elucidates how metal polarization together with\ngeometrical confinement enables a strong plasmon-frequency redshift and\namplified near-field at resonance."
    },
    {
        "anchor": "Metastable bound states of the quasi-bimagnetoexcitons in the lowest\n  Landau levels approximation: Four different spin structures of two electrons and of two holes situated on\nthe lowest Landau levels (LLLs) are taken into account to investigate possible\nbound states of the two-dimensional magnetic biexciton formed of two\nmagnetoexcitons with opposite wave vectors and antiparallel dipole moments. The\nsinglet and triplet states of the spins of two electrons and of two holes\nseparately, as well as of two para- and two ortho-magnetoexcitons are\nconsidered. The general expressions describing the binding energy of the bound\nstates and the normalization conditions characterized by the effective spin\nparameter for the corresponding wave functions are derived. The most favorable\nof the four considered spin configurations happened to be the triplet-triplet\nspin structure of two electrons and of two holes. In its frame a metastable\nbound state with activation barrier comparable with two ionization potentials\nof the magnetoexciton is revealed .",
        "positive": "Angular harmonics of the excitonic polarization conversions effect: We suggest a phenomenological theory of the polarization conversions effect,\nan excitonic analog of the first-order spatial dispersion phenomena which is,\nhowever, observed in the photoluminescence rather than in the passing light.\nThe optical polarization response of a model system of electrically neutral\nquantum dots subject to the magnetic field along the growth axis was calculated\nby means of the pseudospin method. All possible forms of the polarization\nresponse are determined by nine different field-dependent coefficients which\nrepresent, therefore, a natural basis for classification of a variety of\nconversions. Existing experimental data can be well inscribed in this\nclassification scheme. Predictions were made regarding two effects which have\nnot been addressed experimentally."
    },
    {
        "anchor": "Intermolecular Casimir-Polder Forces in Water and near Surfaces: The Casimir-Polder force is an important long range interaction involved in\nadsorption and desorption of molecules in fluids. We explore Casimir-Polder\ninteractions between methane molecules in water, and between a molecule in\nwater near SiO2 and hexane surfaces. Inclusion of the finite molecular size in\nthe expression for the Casimir-Polder energy leads to estimates of the\ndispersion contribution to the binding energies between molecules and between\none molecule and a planar surface.",
        "positive": "Inelastic effects in electron transport studied with wave packet\n  propagation: A time-dependent approach is used to explore inelastic effects during\nelectron transport through few-level systems. We study a tight-binding chain\nwith one and two sites connected to vibrations. This simple but transparent\nmodel gives insight about inelastic effects, their meaning and the\napproximations currently used to treat them. Our time-dependent approach allows\nus to trace back the time sequence of vibrational excitation and electronic\ninterference, the ibrationally introduced time delay and the electronic phase\nshift. We explore a full range of parameters going from weak to strong\nelectron-vibration coupling, from tunneling to contact, from one-vibration\ndescription to the need of including all vibrations for a correct description\nof inelastic effects in transport. We explore the validity of single-site\nresonant models as well as its extension to more sites via molecular orbitals\nand the conditions under which multi-orbital, multi-vibrational descriptions\ncannot be simplified. We explain the physical meaning of the spectral features\nin the second derivative of the electron current with respect to the bias\nvoltage. This permits us to nuance the meaning of the energy value of dips and\npeaks. Finally, we show that finite-band effects lead to electron\nback-scattering off the molecular vibrations in the regime of high-conductance,\nalthough the drop in conductance at the vibrational threshold is rather due to\nthe rapid variation of the vibronic density of states."
    },
    {
        "anchor": "Plasmonic detection of the parity anomaly in a two-dimensional Chern\n  insulator: In this work, we present an analytical study on the surface plasmon\npolaritons in a two dimensional parity anomaly Chern insulator. The connections\nbetween the topology in the bulk implied by the BHZ model and the dispersion\nrelations of the surface plasmons have been revealed. Anisotropy has been\nconsidered during the calculations of the dispersion relations which allows\ndifferent permittivities perpendicular to the conductive plane. Two surface\nplasmon modes each contains two branches of dispersion relations have been\nfound. The topologically non-trivial case gives quite different Hall\nconductivities compared with the trivial one, which leads to significant\nmodifications of the dispersion curves or even the absence of particular branch\nof the surface plasmons. Our investigations pave a possible way for the\ndetection of the parity anomaly in a two-dimensional Chern insulator via\nplasmonic responses.",
        "positive": "Quantum plasmons with optical-range frequencies in doped few-layer\n  graphene: Although plasmon modes exist in doped graphene, the limited range of doping\nachieved by gating restricts the plasmon frequencies to a range that does not\ninclude visible and infrared. Here we show, through the use of first-principles\ncalculations, that the high levels of doping achieved by lithium intercalation\nin bilayer and trilayer graphene shift the plasmon frequencies into the visible\nrange. To obtain physically meaningful results, we introduce a correction of\nthe effect of plasmon interaction across the vacuum separating periodic images\nof the doped graphene layers, consisting of transparent boundary conditions in\nthe direction perpendicular to the layers; this represents a significant\nimprovement over the Exact Coulomb cutoff technique employed in earlier works.\nThe resulting plasmon modes are due to local field efffects and the non-local\nresponse of the material to external electromagnetic fields, requiring a fully\nquantum mechanical treatment. We describe the features of these quantum\nplasmons, including the dispersion relation, losses and field localization. Our\nfindings point to a strategy for fine-tuning the plasmon frequencies in\ngraphene and other two dimensional materials."
    },
    {
        "anchor": "Spin-polarized transport in magnetic tunnel junctions with ZnTe barriers: Magnetic tunnel junctions with wide band gap semiconductor ZnTe barrier were\nfabricated. A very low barrier height and sizable magnetoresistance were\nobserved in the Fe/ZnTe/Fe junctions at room temperature. The nonlinear I-V\ncharacteristic curve confirmed the observed magnetoresistance is due to\nspin-dependent tunneling effect. Temperature dependent study indicated that the\ntotal conductance of the junction is dominated by direct tunneling, with only a\nsmall portion from the hopping conduction through the defect states inside the\nbarrier.",
        "positive": "Singlet exciton optics and phonon-mediated dynamics in oligoacene\n  semiconductor crystals: Organic semiconductor crystals stand out as an efficient, cheap and diverse\nplatform for realising optoelectronic applications. The optical response of\nthese crystals is governed by a rich tapestry of exciton physics. So far,\nlittle is known on the phonon-driven singlet exciton dynamics in this class of\nmaterials. In this joint theory-experiment work, we combine the fabrication of\na high-quality oligoacene semiconductor crystal and characterization via\nphotoluminescence measurements with a sophisticated approach to the microscopic\nmodeling in these crystals. This allows us to investigate singlet exciton\noptics and dynamics. We predict phonon-bottleneck effects in pentacene\ncrystals, where we find dark excitons acting as crucial phonon-mediated\nrelaxation scattering channels. While the efficient singlet fission in\npentacene crystals hampers the experimental observation of this bottleneck\neffect, we reveal both in theory and experiment a distinct polarisation- and\ntemperature-dependence in absorption and photoluminescence spectra of tetracene\ncrystals, including microscopic origin of exciton linewidths, the activation of\nthe higher Davydov states at large temperatures, and polarisation-dependent\nquenching of specific exciton resonances. Our joint theory-experiment study\nrepresents a significant advance in microscopic understanding of singlet\nexciton optics and dynamics in oligoacene crystals."
    },
    {
        "anchor": "A kilobyte rewritable atomic memory: The advent of devices based on single dopants, such as the single atom\ntransistor, the single spin magnetometer and the single atom memory, motivates\nthe quest for strategies that permit to control matter with atomic precision.\nManipulation of individual atoms by means of low-temperature scanning\ntunnelling microscopy provides ways to store data in atoms, encoded either into\ntheir charge state, magnetization state or lattice position. A defining\nchallenge at this stage is the controlled integration of these individual\nfunctional atoms into extended, scalable atomic circuits. Here we present a\nrobust digital atomic scale memory of up to 1 kilobyte (8,000 bits) using an\narray of individual surface vacancies in a chlorine terminated Cu(100) surface.\nThe memory can be read and rewritten automatically by means of atomic scale\nmarkers, and offers an areal density of 502 Terabits per square inch,\noutperforming state-of-the-art hard disk drives by three orders of magnitude.\nFurthermore, the chlorine vacancies are found to be stable at temperatures up\nto 77 K, offering prospects for expanding large-scale atomic assembly towards\nambient conditions.",
        "positive": "Spatially resolved quantum nano-optics of single photons using an\n  electron microscope: We report on the experimental demonstration of single photon state generation\nand characterization in an electron microscope. In this aim we have used low\nintensity relativistic (energy between 60kV and 100 keV) electrons beams\nfocused in a ca 1 nm probe to excite diamond nanoparticles. This triggered\nindividual neutral Nitrogen-vacancies (NV0) centers to emit photon which could\nbe gathered and sent to a Hanbury Brown Twiss intensity interferometer. The\ndetection of a dip in the correlation function at small time delays clearly\ndemonstrates antibunching and thus the creation of non-classical light states.\nSpecifically, we have also demonstrated single photon state detection. We\nunveil the mechanism behind quantum states generation in an electron\nmicroscope, and show that it clearly makes cathodoluminescence the nanometer\nscale analog of photoluminescence rather than electroluminescence. By using an\nextremely small electron probe size and the ability to monitor its position\nwith sub nanometer resolution, we also show the possibility of measuring the\nquantum character of the emitted beam with deep sub wavelength resolution."
    },
    {
        "anchor": "(Quasi-)Quantization of the electrical, thermal, and thermoelectrical\n  conductivities in two and three dimensions: The quantum Hall effect in a 2D electron system expresses a topological\ninvariant, leading to a quantized conductivity. The thermal Hall and\nthermoelectric Nernst conductances in two dimensions are also reported to be\nquantized in specific systems. However, a comprehensive study of these\nquantities within one formalism for quantum Hall systems is so far elusive. In\nthis work, we investigate the Hall, thermal Hall, and Nernst effects\nanalytically and numerically in 2D and 3D. In addition to the quantized values\nfor the Hall and thermal Hall conductances in two dimensions, we also find\nquasi-quantized values in three dimensions, which are the related 2D quanta\nscaled by a characteristic length. The Nernst conductivity is not generally\nquantized. Instead, an integration in energy is required to obtain a\nuniversally (quasi-)quantized thermoelectric quantity.",
        "positive": "Exciton diffusion in WSe2 monolayers embedded in a van der Waals\n  heterostructure: We have combined spatially-resolved steady-state micro-photoluminescence\n($\\mu$PL) with time-resolved photoluminescence (TRPL) to investigate the\nexciton diffusion in a WSe$_2$ monolayer encapsulated with hexagonal boron\nnitride (hBN). At 300 K, we extract an exciton diffusion length $L_X= 0.36\\pm\n0.02 \\; \\mu$m and an exciton diffusion coefficient of $D_X=14.5 \\pm\n2\\;\\mbox{cm}^2$/s. This represents a nearly 10-fold increase in the effective\nmobility of excitons with respect to several previously reported values on\nnonencapsulated samples. At cryogenic temperatures, the high optical quality of\nthese samples has allowed us to discriminate the diffusion of the different\nexciton species : bright and dark neutral excitons, as well as charged\nexcitons. The longer lifetime of dark neutral excitons yields a larger\ndiffusion length of $L_{X^D}=1.5\\pm 0.02 \\;\\mu$m."
    },
    {
        "anchor": "Photon statistics from a resonantly driven quantum dot: Photon correlations in the emission of a resonantly driven quantum dot are\ninvestigated, accounting for the influence of the solid-state phonon\nenvironment. An analytical expression is derived for the second-order\nfluorescence intensity correlation function, from which regimes of correlated\nand uncorrelated photon emission are predicted as the driving field is varied.\nExperiments to investigate this effect would provide valuable insight into\nquantum dot carrier-phonon dynamics and are feasible with current technology.",
        "positive": "Josephson Coupled Moore-Read States: We study a quantum Hall bilayer system of bosons at total filling factor $\\nu\n= 1$, and study the phase that results from short ranged pair-tunneling\ncombined with short ranged interlayer interactions. We introduce two exactly\nsolvable model Hamiltonians which both yield the coupled Moore-Read state\n[Phys.~Rev.~Lett.~{\\bf 108}, 256809 (2012)] as a ground state, when projected\nonto fixed particle numbers in each layer. One of these Hamiltonians describes\na gapped topological phase while the other is gapless. However, on introduction\nof a pair tunneling term, the second system becomes gapped and develops the\nsame topological order as the gapped Hamiltonian. Supported by the exact\nsolution of the full zero-energy quasihole spectrum and a conformal field\ntheory approach, we develop an intuitive picture of this system as two coupled\ncomposite fermion superconductors. In this language, pair tunneling provides a\nJosephson coupling of the superconducting phases of the two layers, and gaps\nout the Goldstone mode associated with particle transport between the layers.\nIn particular, this implies that quasiparticles are confined between the\nlayers. In the bulk, the resulting phase has the topological order of the\nHalperin 220 phase with $U(1)_2\\times U(1)_2$ topological order, but it is\nrealized in the symmetric/antisymmetric-basis of the layer index. Consequently,\nthe edge spectrum at a fixed particle number reveals an unexpected $U(1)_4\n\\times U(1)$ structure."
    },
    {
        "anchor": "Controlling superconducting spin flow with spin-flip immunity using a\n  single homogeneous ferromagnet: Spin transport via electrons is typically plagued by Joule heating and short\ndecay lengths due to spin-flip scattering. It is known that dissipationless\nspin currents can arise when using conventional superconducting contacts, yet\nthis has only been experimentally demonstrated when using intricate\nmagnetically inhomogeneous multilayers, or in extreme cases such as half-metals\nwith interfacial magnetic disorder. Moreover, it is unknown how such spin\nsupercurrents decay in the presence of spin-flip scattering. Here, we present a\nmethod for generating a spin supercurrent by using only a single homogeneous\nmagnetic element. Remarkably, the spin supercurrent generated in this way does\nnot decay spatially, in stark contrast to normal spin currents that remain\npolarized only up to the spin relaxation length. We also expose the existence\nof a superconductivity-mediated torque even without magnetic inhomogeneities,\nshowing that the different components of the spin supercurrent polarization\nrespond fundamentally differently to a change in the superconducting phase\ndifference. This establishes a mechanism for tuning dissipationless spin and\ncharge flow separately, and confirms the advantage that superconductors can\noffer in spintronics.",
        "positive": "Tunable transmission via quantum state evolution in oval quantum dots: We explore the quantum transmission through open oval shaped quantum dots.\nThe transmission spectra show periodic resonances and, depending on the\ngeometry parameter, a strong suppression of the transmission for low energies.\nApplying a weak perpendicular magnetic field changes this situation drastically\nand introduces a large conductance. We identify the underlying mechanisms being\npartially due to the specific shape of the oval that causes a systematic\ndecoupling of a substantial number of states from the leads. Importantly a\npairwise destructive interference of the transmitting states is encountered\nthereby leading to the complete conductance suppression. Coupling properties\nand interferences can be tuned via a weak magnetic field. These properties are\nrobust with respect to the presence of disorder in the quantum dot."
    },
    {
        "anchor": "Glass-like Electronics in Vanadium Dioxide: Functional materials can offer new paradigms for miniaturized and\nenergy-efficient electronics, providing a complementary or even alternative\nplatform to metal-oxide-semiconductors. Here we report on electronically\naccessible long-lived structural states in Vanadium Dioxide that can offer a\nscheme for data storage and processing. We show that such states can be\nelectrically manipulated and tracked beyond 10,000 seconds after excitation,\nexhibiting similar features of glasses, which are beyond the classic\nmetastability in Mott systems. Glass-like electronics can potentially overcome\nsome of the fundamental limitations in conventional metal-oxide-semiconductor\nelectronics, and open avenues for neuromorphic computation and multi-level\nmemories.",
        "positive": "Thermal radiation and near-field energy density of thin metallic films: We study the properties of thermal radiation emitted by a thin dielectric\nslab, employing the framework of macroscopic fluctuational electrodynamics.\nParticular emphasis is given to the analytical construction of the required\ndyadic Green's functions. Based on these, general expressions are derived for\nboth the system's Poynting vector, describing the intensity of propagating\nradiation, and its energy density, containing contributions from\nnon-propagating modes which dominate the near-field regime. An extensive\ndiscussion is then given for thin metal films. It is shown that the radiative\nintensity is maximized for a certain film thickness, due to Fabry-Perot-like\nmultiple reflections inside the film. The dependence of the near-field energy\ndensity on the distance from the film's surface is governed by an interplay of\nseveral length scales, and characterized by different exponents in different\nregimes. In particular, this energy density remains finite even for arbitrarily\nthin films. This unexpected feature is associated with the film's low-frequency\nsurface plasmon polariton. Our results also serve as reference for current\nnear-field experiments which search for deviations from the macroscopic\napproach."
    },
    {
        "anchor": "Resonant Tunneling Spectroscopy of Interacting Localised States --\n  Observation of the Correlated Current Through Two Impurities: We study effects of Coulomb interactions between localised states in a\npotential barrier by measuring resonant-tunneling spectra with a small bias\napplied along the barrier. In the ohmic regime the conductance of 0.2um--gate\nlateral GaAs microstructures shows distinct peaks associated with individual\nlocalised states. However, when an electric field is applied new states start\ncontributing to the current, which becomes a correlated electron flow through\ntwo interacting localised states. Several situations of such correlations have\nbeen observed, and the conclusions are confirmed by calculations.",
        "positive": "Large Magnetoresistance Ratio in Ferromagnetic Single-Electron\n  Transistors in the Strong Tunneling Regime: We study transport through a ferromagnetic single-electron transistor. The\nresistance is represented as a path integral, so that systems where the tunnel\nresistances are smaller than the quantum resistance can be investigated. Beyond\nthe low order sequential tunneling and co-tunneling regimes, a large\nmagnetoresistance ratio at sufficiently low temperatures is found. In the\nopposite limit, when the thermal energy is larger than the charging energy, the\nmagnetoresistance ratio is only slightly enhanced."
    },
    {
        "anchor": "Resonant photoluminescence and dynamics of a hybrid Mn-hole spin in a\n  positively charged magnetic quantum dot: We analyze, through resonant photoluminescence, the spin dynamics of an\nindividual magnetic atom (Mn) coupled to a hole in a semiconductor quantum dot.\nThe hybrid Mn-hole spin and the positively charged exciton in a CdTe/ZnTe\nquantum dot forms an ensemble of $\\Lambda$ systems which can be addressed\noptically. Auto-correlation of the resonant photoluminescence and resonant\noptical pumping experiments are used to study the spin relaxation channels in\nthis multilevel spin system. We identified for the hybrid Mn-hole spin an\nefficient relaxation channel driven by the interplay of the Mn-hole exchange\ninteraction and the coupling to acoustic phonons. We also show that the optical\n$\\Lambda$ systems are connected through inefficient spin-flips than can be\nenhanced under weak transverse magnetic field. The dynamics of the resonant\nphotoluminescence in a p-doped magnetic quantum dot is well described by a\ncomplete rate equation model. Our results suggest that long lived hybrid\nMn-hole spin could be obtained in quantum dot systems with large\nheavy-hole/light-hole splitting.",
        "positive": "Spin-wave spectroscopy of individual ferromagnetic nanodisks: The increasing demand for ultrahigh data storage densities requires\ndevelopment of 3D magnetic nanostructures. In this regard, focused electron\nbeam induced deposition (FEBID) is a technique of choice for direct-writing of\nvarious complex nano-architectures. However, intrinsic properties of\nnanomagnets are often poorly known and can hardly be assessed by local optical\nprobe techniques. Here, we demonstrate spatially resolved spin-wave\nspectroscopy of individual circular magnetic elements with radii down to 100\nnm. The key component of the setup is a microwave antenna whose microsized\ncentral part is placed over a movable substrate with well-separated CoFe-FEBID\nnanodisks. The circular symmetry of the disks gives rise to standing spin-wave\nresonances and allows for the deduction of the saturation magnetization and the\nexchange stiffness of the material using an analytical theory. The presented\napproach is especially valuable for the characterization of direct-write\nelements opening new horizons for 3D nanomagnetism and magnonics."
    },
    {
        "anchor": "Evidence of Flat Bands and Correlated States in Buckled Graphene\n  Superlattices: Two-dimensional atomic crystals can radically change their properties in\nresponse to external influences such as substrate orientation or strain,\nresulting in essentially new materials in terms of the electronic structure. A\nstriking example is the creation of flat-bands in bilayer-graphene for certain\n'magic' twist-angles between the orientations of the two layers. The quenched\nkinetic-energy in these flat-bands promotes electron-electron interactions and\nfacilitates the emergence of strongly-correlated phases such as\nsuperconductivity and correlated-insulators. However, the exquisite fine-tuning\nrequired for finding the magic-angle where flat-bands appear in twisted-bilayer\ngraphene, poses challenges to fabrication and scalability. Here we present an\nalternative route to creating flat-bands that does not involve fine tuning.\nUsing scanning tunneling microscopy and spectroscopy, together with numerical\nsimulations, we demonstrate that graphene monolayers placed on an\natomically-flat substrate can be forced to undergo a buckling-transition,\nresulting in a periodically modulated pseudo-magnetic field, which in turn\ncreates a post-graphene material with flat electronic bands. Bringing the\nFermi-level into these flat-bands by electrostatic doping, we observe a\npseudogap-like depletion in the density-of-states, which signals the emergence\nof a correlated-state. The described approach of 2D crystal buckling offers a\nstrategy for creating other superlattice systems and, in particular, for\nexploring interaction phenomena characteristic of flat-bands.",
        "positive": "Majorana Superconducting Qubit: We propose a platform for universal quantum computation that uses\nconventional $s$-wave superconducting leads to address a topological qubit\nstored in spatially separated Majorana bound states in a multi-terminal\ntopological superconductor island. Both the manipulation and read-out of this\n\"Majorana superconducting qubit\" are realized by tunnel couplings between\nMajorana bound states and the superconducting leads. The ability of turning on\nand off tunnel couplings on-demand by local gates enables individual qubit\naddressability while avoiding cross-talk errors. By combining the scalability\nof superconducting qubit and the robustness of topological qubits, the Majorana\nsuperconducting qubit may provide a promising and realistic route towards\nquantum computation."
    },
    {
        "anchor": "Plasmons in Two-Dimensional Topological Insulators: We analyze collective excitations in models of two-dimensional topological\ninsulators using the random phase approximation. In a two-dimensional extension\nof the Su-Schrieffer-Heeger model, edge plasmonic excitations with induced\ncharge-density distributions localized at the boundaries of the system are\nfound in the topologically non-trivial phase, dispersing similarly as\none-dimensional bulk plasmons in the conventional Su-Schrieffer-Heeger chain.\nFor two-dimensional bulk collective modes, we reveal regimes of enhanced\ninter-band wave function correlations, leading to characteristic hardening and\nsoftening of inter- and intra-band bulk plasmonic branches, respectively. In\nthe two-dimensional Haldane Chern insulator model, chiral, uni-directional edge\nplasmons in nano-ribbon architectures are observed, which can be characterized\nby an effective Coulomb interaction cross section. Bulk collective excitations\nin the two-dimensional Haldane model are shown to be originated by\nsingle-particle band structure details in different topological phases.",
        "positive": "Interference and transport properties of conductions electrons on the\n  surface of a topological insulator: The surface conductivity for conduction electrons with a fixed chirality in a\ntopological insulator with impurities scattering is considered. The surface\nexcitations are described by the Weyl Hamiltonian. For a finite chemical\npotential one projects out the hole band and one obtains a single electronic\nband with a fixed chirality. One obtains a model of spinless electrons which\nexperience a half vortex when they return to the origin. As a result the\nconductivity is equivalent to a spinless problem with correlated noise which\ngives rise to anti-localization. We compute conductivity as a function of\nfrequency and compare our results with the $Raman$ shift measurement for\n$Bi_{2}Se_{3}$."
    },
    {
        "anchor": "Effects of charging energy on SINIS tunnel junction thermometry: We have investigated theoretically the effects of the charging energy to the\nnormal metal--insulator--superconductor (NIS) tunnel junction used as a\nthermometer. We demonstrate by numerical calculations how the charging effects\nmodify NIS thermometry, and how the voltage--to--temperature response and the\nresponsivity $|dV/dT|$ of a current biased thermometer are affected. In\naddition, we show that the responsivity of the thermometer can be modulated\nwith an additional gate electrode. The maximum responsivity is achieved when\nthe Coulomb blockade is maximal, i.e. with a closed gate.",
        "positive": "Hydrodynamic theory of chiral angular momentum generation in metals: We present a hydrodynamic theory to describe a chiral electron system with a\nWeyl spin-orbit interaction on a field-theoretic basis. Evaluating the momentum\nflux density as a linear response to a driving electric field, we derive an\nequation of motion for the orbital angular momentum. It is shown that the\nchiral nature leads to a dynamic bulk angular momentum generation by inducing a\nglobal torque as a response to the applied field. The steady state angular\nmomentum is calculated taking account of rotational viscosity."
    },
    {
        "anchor": "The topological inequivalence of Hall bar versus Corbino geometries in\n  real space: This work discusses the effect of topology in the frame of direct Coulomb\ninteractions, considering two distinct geometries, namely the Hall bar and the\nCorbino disc. In the mainstream approaches to the quantized Hall effect, the\nconsequences of interactions are usually underestimated. Here, we investigate\nthe electron number density, potential and current distributions within the\nscreening theory that considers electron-electron interactions. Inclusion of\ndirect Coulomb interaction and realistic boundary conditions result in local\nmetal-like compressible and (Topological) insulator-like incompressible\nregions. Consequently, we show that the bulk of both geometries in coordinate\nspace is not incompressible throughout the quantized Hall plateau. Furthermore,\nplacing two inner contacts within the Hall bar geometry shows that the\nquantization is unaffected by changing the genus number in real space. Finally,\nwe propose novel experiments which will enable us to distinguish the\ntopological properties of the two geometries in the configuration space.",
        "positive": "Bulk detection of time-dependent topological transitions in quenched\n  chiral models: The topology of one-dimensional chiral systems is captured by the winding\nnumber of the Hamiltonian eigenstates. Here we show that this invariant can be\nread-out by measuring the mean chiral displacement of a single-particle\nwavefunction that is connected to a fully localized one via a unitary and\ntranslational-invariant map. Remarkably, this implies that the mean chiral\ndisplacement can detect the winding number even when the underlying Hamiltonian\nis quenched between different topological phases. We confirm experimentally\nthese results in a quantum walk of structured light."
    },
    {
        "anchor": "Does adsorption in a single nanogroove exhibit hysteresis?: A simple fluid, in a microscopic capillary capped at one end, is studied by\nmeans of fundamental measure density functional. The model represents a single,\ninfinitely long nanogroove with long-range wall-fluid attractive (dispersion)\nforces. It is shown that the presence or absence of hysteresis in adsorption\nisotherms is determined by wetting properties of the wall as follows: Above\nwetting temperature, $T_w$, appropriate to a single wall of the groove, the\nadsorption is a continuous process corresponding to a rise of a meniscus from\nthe capped to the open end of the groove. For a sufficiently deep capillary the\nmeniscus rise is shown to be a steep, yet continuous process taking place near\nthe capillary condensation of a corresponding slit. However, for temperatures\nlower than $T_w$ the condensation exhibits a first-order transition accompanied\nby hysteresis of the adsorption isotherm. Finally, it is shown that hysteresis\nmay occur even for $T>T_w$ as a consequence of prewetting on the side and\nbottom walls of the groove.",
        "positive": "Phase-sensitive bichromatic photoresistance in a two-dimensional\n  electron gas: We have studied microwave photoresistance in a two-dimensional electron\nsystem subject to two radiation fields (frequencies $\\omega_1$ and $\\omega_2$)\nusing quantum kinetic equation. We have found that when $\\omega_2/\\omega_1= 1 +\n2/N$, where $N$ is an integer, and both waves have the same polarization, the\ndisplacement mechanism gives rise to a new, phase-sensitive photoresistance.\nThis photoresistance oscillates with the magnetic field and can be a good\nfraction of the total photoresistance under typical experimental conditions.\nThe inelastic mechanism, on the other hand, gives zero phase-sensitive\nphotoresistance if the radiation fields are circularly polarized."
    },
    {
        "anchor": "Two-dimensional metal-insulator-transition as a potential fluctuation\n  driven semiclassical transport phenomenon: We theoretically consider the carrier density tuned (apparent)\ntwo-dimensional (2D) metal-insulator-transition (MIT) in semiconductor\nheterostructure-based 2D carrier systems as arising from a classical\npercolation phenomenon in the inhomogeneous density landscape created by the\nlong-range potential fluctuations induced by random quenched charged impurities\nin the environment. The long-range Coulomb disorder inherent in semiconductors\nproduces strong potential fluctuations in the 2D system where a fraction of the\ncarriers gets trapped or classically localized, leading to a mixed 2-component\nsemiclassical transport behavior at intermediate densities where a fraction of\nthe carriers is mobile and another fraction immobile. At high carrier density,\nall the carriers are essentially mobile whereas at low carrier density all the\ncarriers are essentially trapped since there is no possible percolating\ntransport path through the lake-and-mountain inhomogeneous potential landscape.\nThe low-density situation with no percolation would mimic an insulator whereas\nthe high-density situation with allowed percolating paths through the\nlake-and-mountain energy landscape would mimic a metal with the system\nmanifesting an apparent MIT in between. We calculate the transport properties\nas a function of carrier density, impurity density, impurity location, and\ntemperature using a 2-component (trapped and mobile carriers) effective medium\ntheory. Our theoretically calculated transport properties are in good\nqualitative agreement with the experimentally observed 2D MIT phenomenology in\n2D electron and hole systems. We find a high (low) density metallic\n(insulating) temperature-dependence of the 2D resistivity, and an\nintermediate-density crossover behavior which could be identified with the\nexperimentally observed 2D MIT.",
        "positive": "Logical operations using phenyl ring: Exploiting the effects of quantum interference we put forward an idea of\ndesigning three primary logic gates, OR, AND and NOT, using a benzene molecule.\nUnder a specific molecule-lead interface geometry, anti-resonant states appear\nwhich play the crucial role for AND and NOT operations, while for OR gate no\nsuch states are required. Our analysis leads to a possibility of designing\nlogic gates using simple molecular structure which might be significant in the\narea of molecular electronics."
    },
    {
        "anchor": "Skyrmion confinement in ultrathin film nanostructures in the presence of\n  Dzyaloshinskii-Moriya interaction: We study the modification of micromagnetic configurations in nanostructures,\ndue to the Dzyaloshinskii-Moriya interaction (DMI) that appear at the interface\nof an ultrathin film. We show that this interaction leads to new micromagnetic\nboundary conditions that bend the magnetization at the edges. We explore\nseveral cases of ultrathin film nanostructures that allow analytical\ncalculations (1D systems, domain walls, cycloids and skyrmions), compare with\nfully numerical calculations, and show that a good physical understanding of\nthis new type of micromagnetics can be reached. We particularly focus on\nskyrmions confined in circular nanodots and show that edges allow for the\nisolation of single skyrmions for a large range of the DMI parameter.",
        "positive": "Large photoluminescence enhancement by an out-of-plane magnetic field in\n  exfoliated WS$_2$ flakes: We report an out-of-plane magnetic field induced large photoluminescence\nenhancement in WS${}_2$ flakes at $4$ K, in contrast to the photoluminescence\nenhancement provided by in-plane field in general. Two mechanisms for the\nenhancement are proposed. One is a larger overlap of electron and hole caused\nby the magnetic field induced confinement. The other is that the energy\ndifference between $\\Lambda$ and K valleys is reduced by magnetic field, and\nthus enhancing the corresponding indirect-transition trions. Meanwhile, the\nLand\\'e g factor of the trion is measured as $-0.8$, whose absolute value is\nmuch smaller than normal exciton, which is around $|-4|$. A model for the trion\ng factor is presented, confirming that the smaller absolute value of Land\\'e g\nfactor is a behavior of this $\\Lambda$-K trion. By extending the valley space,\nwe believe this work provides a further understanding of the valleytronics in\nmonolayer transition metal dichalcogenides."
    },
    {
        "anchor": "Quantum Hall effect in n-p-n and n-2D Topological Insulator-n junctions: We have studied quantized transport in HgTe wells with inverted band\nstructure corresponding to the two-dimensional topological insulator phase (2D\nTI) with locally-controlled density allowing n-p-n and n-2D TI-n junctions. The\nresistance reveals the fractional plateau $2h/e^{2}$ in n-p-n regime in the\npresence of the strong perpendicular magnetic field. We found that in n-2D TI-n\nregime the plateaux in resistance in not universal and results from the edge\nstate equilibration at the interface between chiral and helical edge modes. We\nprovided the simple model describing the resistance quantization in n-2D TI-n\nregime.",
        "positive": "Quantum corrections to transport in graphene: a trajectory-based\n  semiclassical analysis: We review a calculation of the quantum corrections to electrical transport in\ngraphene using the trajectory-based semiclassical method. Compared to\nconventional metals, for graphene the semiclassical propagator contains an\nadditional pseudospin structure, which influences the results for weak\nlocalization, and interaction-induced effects, such as the Altshuler-Aronov\ncorrection and dephasing. Our results apply to a sample of graphene that is\ndoped away from the Dirac point and subject to a smooth disorder potential,\nsuch that electrons follow classical trajectories. In such system, the\nEhrenfest time enters as an additional timescale."
    },
    {
        "anchor": "Magneto-Crystalline Composite Topological Defects and Half-Hopfions: We consider a new class of topological defects in chiral magnetic crystals\nsuch as FeGe and MnSi. These are composite topological defects that arise when\nskyrmions in the magnetic order intersect with twin boundaries in the\nunderlying crystalline lattice. We show that the resulting stable\nconfigurations are a new type of defect that can be viewed as half-hopfions.",
        "positive": "Unconventional charge and spin dependent transport properties of a\n  graphene nanoribbon with line-disorder: Electronic transport with a line (or a few lines) of Anderson type disorder\nin a zigzag graphene nanoribbon is investigated in presence of Rashba\nspin-orbit interaction. Such line disorders give rise to peculiar behavior in\nboth charge as well as spin-polarized transmission in the following sense. In\nthe weak disorder regime, the charge transport data show Anderson localization\nup to a certain disorder strength, beyond which the extended states emerge and\nstart dominating over the localized states. These results are the hallmark\nsignature of a selectively disordered (as opposed to bulk disorder) graphene\nnanoribbon. However, the spin-polarized transport shows a completely\ncontradicting behavior. Further, the structural symmetries are shown to have an\nimportant role in the spintronic properties of the nanoribbons. Moreover, the\nedge-disorder scenario (disorder selectively placed at the edges) seems to hold\npromise for the spin-filter and switching device applications."
    },
    {
        "anchor": "Magnetization Reversal of 50-nm-wide Ni81Fe19 Nanostripes by Ultrashort\n  Magnons in Yttrium Iron Garnet for Memory-Enhanced Magnonic Circuits: Spin waves (magnons) can enable wave-based neuromorphic computing by which\none aims at overcoming limitations inherent to conventional electronics and the\nvon Neumann architecture. In this study, we explore the storage of magnon\nsignals and the magnetization switching of periodic and aperiodic arrays of\nNi81Fe19 (Py) nanostripes with widths (w) between 50 nm and 200 nm. Spin waves\nexcited with low microwave power in yttrium iron garnet induce the reversal of\nthe nanostripes of different w in a small opposing field. Exploiting\nmicrowave-to-magnon transducers for magnon modes with ultrashort wavelengths,\nwe demonstrate the reversal of 50-nm-wide Py nanostripes by magnons with\nwavelength ~ 100 nm after they have propagated over 25 micrometer in YIG. The\nfindings are important for designing a magnon-based in-memory computing device.",
        "positive": "Electrical spin injection from ferromagnet into an InAs heterostructures\n  through MgO tunnel barrier: We have investigated electrical spin injection from Ni81Fe19 into an InAs\nquantum well through MgO tunneling barrier for potential application to\nInAs-based spin field effect transistor. Injected spin polarized current were\ndetected in both nonlocal and local spin valve set-ups and the spin diffusion\nlength and spin injection efficiency were analyzed. The spin diffusion length\nwas estimated to be 1.6 {\\mu}m in nonlocal set-up at 1.4 K. The spin\npolarization of Ni81Fe19/MgO/InAs as-deposited sample was relealed to be 6.9 %,\nwhile increased spin polarization of 8.9 % was observed by additional thermal\ntreatment."
    },
    {
        "anchor": "Niobium and niobium nitride SQUIDs based on anodized nanobridges made\n  with an Atomic Force Microscope: We present a fabrication method of superconducting quantum interference\ndevices (SQUIDs) based on direct write lithography with an Atomic Force\nMicroscope (AFM). This technique involves maskless local anodization of Nb or\nNbN ultrathin films using the voltage biased tip of the AFM. The SQUIDs are of\nweak-link type, for which two geometries have been tested: Dayem and variable\nthickness nanobridges. The magnetic field dependence of the maximum\nsupercurrent Ic(flux) in resulting SQUIDs is thoroughly measured for different\nweak link geometries and for both tested materials. It is found that the\nmodulation shape and depth of Ic(flux) curves are greatly dependent on the weak\nlink size. We analyze the results taking into account the kinetic inductance of\nnanobridges and using the Likharev-Yakobson model. Finally we show that the\npresent resolution reached by this technique (20nm) enables us to fabricate Nb\nweak-links which behavior approaches those of ideal Josephson junctions.",
        "positive": "Symmetric excitation and de-excitation of a cavity QED system: We calculate the time evolution of a cavity-QED system subject to a time\ndependent sinusoidal drive. The drive is modulated by an envelope function with\nthe shape of a pulse. The system consists of electrons embedded in a\nsemiconductor nanostructure which is coupled to a single mode quantized\nelectromagnetic field. The electron-electron as well as photon-electron\ninteraction is treated exactly using \"exact numerical diagonalization\" and the\ntime evolution is calculated by numerically solving the equation of motion for\nthe system's density matrix. We find that the drive causes symmetric excitation\nand de-excitation where the system climbs up the Jaynes-Cummings ladder and\ndescends back down symmetrically into its original state. This effect persists\neven in the ultra-strong coupling regime where the Jaynes-Cummings model is\ninvalid. We investigate the robustness of this symmetric behavior with respect\nto the drive de-tuning and pulse duration."
    },
    {
        "anchor": "Dynamical correlations in electronic transport through a system of\n  coupled quantum dots: Current auto- and cross-correlations are studied in a system of two\ncapacitively coupled quantum dots. We are interested in a role of Coulomb\ninteraction in dynamical correlations, which occur outside the Coulomb blockade\nregion (for high bias). After decomposition of the current correlation\nfunctions into contributions between individual tunneling events, we can show\nwhich of them are relevant and lead to sub-/supper-Poissonian shot noise and\nnegative/positive cross-correlations. The results are differentiated for a weak\nand strong inter-dot coupling. Interesting results are for the strong coupling\ncase when electron transfer in one of the channel is strongly correlated with\ncharge drag in the second channel. We show that cross-correlations are\nnon-monotonic functions of bias voltage and they are in general negative\n(except some cases with asymmetric tunnel resistances). This is effect of local\npotential fluctuations correlated by Coulomb interaction, which mimics the\nPauli exclusion principle.",
        "positive": "Peculiar atomic bond nature in platinum monatomic chains: Metal atomic chains have been reported to change their electronic or magnetic\nproperties by slight mechanical stimulus. However, the mechanical response has\nbeen veiled because of lack of information on the bond nature. Here, we clarify\nthe bond nature in platinum (Pt) monatomic chains by our developed in-situ\ntransmission electron microscope method. The stiffness is measured with sub N/m\nprecision by quartz length-extension resonator. The bond stiffnesses at the\nmiddle of the chain and at the connecting to the base are estimated to be 25\nand 23 N/m, respectively, which are higher than the bulk counterpart.\nInterestingly, the bond length of 0.25 nm is found to be elastically stretched\nto 0.31 nm, corresponding to 24% in strain. Such peculiar bond nature could be\nexplained by a novel concept of \"string tension\". This study is a milestone\nthat will significantly change the way we think about atomic bonds in\none-dimensional substance."
    },
    {
        "anchor": "Engineering topological surface-states: HgS, HgSe and HgTe: Using density functional electronic structure calculations, we establish the\nconsequences of surface termination and modification on protected\nsurface-states of metacinnabar (beta-HgS). Whereas we find that the Dirac cone\nis isotropic and well-separated from the valence band for the (110) surface, it\nis highly anisotropic at the pure (001) surface. We demonstrate that the\nanisotropy is modified by surface passivation because the topological\nsurface-states include contributions from dangling bonds. Such dangling bonds\nexist on all pure surfaces within the whole class HgX with X = S, Se, or Te and\ndirectly affect the properties of the Dirac cone. Surface modifications also\nalter the spatial location (depth and decay length) of the topologically\nprotected edge-states which renders them essential for the interpretation of\nphotoemission data.",
        "positive": "Robust Majorana bound state in pseudo-spin domain wall of 2-D\n  topological insulator: We investigate helical edge states (HES) emerging at the composite domain\nwall of spin and pseudo-spin degrees of freedom in a 2-D bulk governed by the\nBernevig-Hughes-Zhang Hamiltonian which underwent quantum spin Hall to\nanomalous Hall transition. We numerically study the stability of Majorana bound\nstate (MBS) formed due to proximity induced superconductivity in these helical\nedge states. We establish exceptional robustness of MBS against moderate\nchemical potential or magnetic disorder owing to the existence of the\nsimultaneous orthogonality between the right and the left moving modes both in\nspin and pseudo-spin space. Hence our proposal could pave the way to realizing\nrobust Majorana bound state on 2D platforms."
    },
    {
        "anchor": "Layer Number Determination and Thickness-dependent Properties of\n  Graphene Grown on SiC: The electronic properties of few-layer graphene grown on the carbon-face of\nsilicon carbide (SiC) are found to be strongly dependent on the number of\nlayers. The carrier mobility is larger in thicker graphene because\nsubstrate-related scattering is reduced in the higher layers. The carrier\ndensity dependence of the mobility is qualitatively different in thin and thick\ngraphene, with the transition occurring at about 2 layers. The mobility\nincreases with carrier density in thick graphene, similar to multi-layer\ngraphene exfoliated from natural graphite, suggesting that the individual\nlayers are still electrically coupled in spite of reports recording non-Bernal\nstacking order in C-face grown graphene. The Hall coefficient peak value is\nreduced in thick graphene due to the increased density of states. A reliable\nand rapid characterization tool for the layer number is therefore highly\ndesirable. To date, AFM height determination and Raman scattering are typically\nused since the optical contrast of graphene on SiC is weak. However, both\nmethods suffer from low throughput. We show that the scanning electron\nmicroscopy (SEM) contrast can give similar results with much higher throughput.",
        "positive": "The one-dimensional Stefan problem with non-Fourier heat conduction: We investigate the one-dimensional growth of a solid into a liquid bath,\nstarting from a small crystal, using the Guyer-Krumhansl and Maxwell-Cattaneo\nmodels of heat conduction. By breaking the solidification process into the\nrelevant time regimes we are able to reduce the problem to a system of two\ncoupled ordinary differential equations describing the evolution of the\nsolid-liquid interface and the heat flux. The reduced formulation is in good\nagreement with numerical simulations. In the case of silicon, differences\nbetween classical and non-classical solidification kinetics are relatively\nsmall, but larger deviations can be observed in the evolution in time of the\nheat flux through the growing solid. From this study we conclude that the heat\nflux provides more information about the presence of non-classical modes of\nheat transport during phase-change processes."
    },
    {
        "anchor": "The exchange bias phenomenon in uncompensated interfaces: Theory and\n  Monte Carlo simulations: We performed Monte Carlo simulations in a bilayer system composed by two thin\nfilms, one ferromagnetic (FM) and the other antiferromagnetic (AFM). Two\nlattice structures for the films were considered: simple cubic (sc) and a body\ncenter cubic (bcc). In both lattices structures we imposed an uncompensated\ninterfacial spin structure, in particular we emulated a FeF2-FM system in the\ncase of the (bcc) lattice. Our analysis focused on the incidence of the\ninterfacial strength interactions between the films J_eb and the effect of\nthermal fluctuations on the bias field H_EB. We first performed Monte Carlo\nsimulations on a microscopic model based on classical Heisenberg spin\nvariables. To analyze the simulation results we also introduced a simplified\nmodel that assumes coherent rotation of spins located on the same layer\nparallel to the interface. We found that, depending on the AFM film anisotropy\nto exchange ratio, the bias field is either controlled by the intrinsic pinning\nof a domain wall parallel to the interface or by the stability of the first AFM\nlayer (quasi domain wall) near the interface.",
        "positive": "Enhanced Light Emission from the Ridge of Two-dimensional InSe Flakes: InSe, a newly rediscovered two-dimensional (2D) semiconductor, possesses\nsuperior electrical and optical properties as a direct bandgap semiconductor\nwith high mobility from bulk to atomically thin layers, drastically different\nfrom transition metal dichalcogenides (TMDCs) in which the direct bandgap only\nexists at the single layer limit. However, absorption in InSe is mostly\ndominated by an out-of-plane dipole contribution which results in the limited\nabsorption of normally incident light which can only excite the in-plane dipole\nat resonance. To address this challenge, we have explored a unique geometric\nridge state of the 2D flake without compromising the sample quality. We\nobserved the enhanced absorption at the ridge over a broad range of excitation\nfrequencies from photocurrent and photoluminescence (PL) measurements. In\naddition, we have discovered new PL peaks at low temperature due to defect\nstates on the ridge, which can be as much as ~ 60 times stronger than the\nintrinsic PL peak of InSe. Interestingly, the PL of the defects is highly\ntunable through an external electrical field, which can be attributed to the\nStark effect of the localized defects. InSe ridges thus provide new avenues for\nmanipulating light-matter interaction and defect-engineering which are vitally\ncrucial for novel optoelectronic devices based on 2D semiconductors."
    },
    {
        "anchor": "Klein-like tunneling of sound via negative index metamaterials: Klein tunneling is a counterintuitive quantum-mechanical phenomenon,\npredicting perfect transmission of relativistic particles through higher energy\nbarriers. This phenomenon was shown to be supported at normal incidence in\ngraphene due to pseudospin conservation. Here I show that Klein tunneling\nanalogue can occur in classical systems, and remarkably, not relying on\nmimicking graphene's spinor wavefunction structure. Instead, the mechanism\nrequires a particular form of constitutive parameters of the penetrated medium,\nyielding transmission properties identical to the quantum tunneling in\ngraphene. I demonstrate this result by simulating tunneling of sound in a\ntwo-dimensional acoustic metamaterial. More strikingly, I show that by\nintroducing a certain form of anisotropy, the tunneling can be made unimpeded\nfor any incidence angle, while keeping most of its original Klein dispersion\nproperties. This phenomenon may be denoted by the omnidirectional Klein-like\ntunneling. The new tunneling mechanism and its omnidirectional variant may be\nuseful for applications requiring lossless and direction-independent\ntransmission of classical waves.",
        "positive": "Experimental observation of the curvature-induced asymmetric spin-wave\n  dispersion in hexagonal nanotubes: Theoretical and numerical studies on curved magnetic nano-objects predict\nnumerous exciting effects that can be referred to as magneto-chiral effects,\nwhich do not originate from the intrinsic Dzyaloshinskii-Moriya interaction or\nsurface-induced anisotropies. The origin of these chiral effects is the\nisotropic exchange or the dipole-dipole interaction present in all magnetic\nmaterials but renormalized by the curvature. Here, we demonstrate\nexperimentally that curvature induced effects originating from the\ndipole-dipole interaction are directly observable by measuring spin-wave\npropagation in magnetic nanotubes with hexagonal cross section using time\nresolved scanning transmission X-ray microscopy. We show that the dispersion\nrelation is asymmetric upon reversal of the wave vector when the propagation\ndirection is perpendicular to the static magnetization. Therefore\ncounter-propagating spin waves of the same frequency exhibit different\nwavelenghts. Hexagonal nanotubes have a complex dispersion, resulting from\nspin-wave modes localised to the flat facets or to the extremely curved regions\nbetween the facets. The dispersion relations obtained experimentally and from\nmicromagnetic simulations are in good agreement. %The asymmetric spin-wave\ntransport is present for all modes, promoting hexagonal nanotubes for magnonic\napplications. These results show that spin-wave transport is possible in 3D,\nand that the dipole-dipole induced magneto-chiral effects are significant."
    },
    {
        "anchor": "Entangling Pairs of Nano-Cantilevers, Cooper-Pair Boxes and Mesoscopic\n  Teleportation: We propose two schemes to establish entanglement between two mesoscopic\nquantum systems through a third mesoscopic quantum system. The first scheme\nentangles two nano-mechanical oscillators in a non-Gaussian entangled state\nthrough a Cooper pair box. Entanglement detection of the nano-mechanical\noscillators is equivalent to a teleportation experiment in a mesoscopic\nsetting. The second scheme can entangle two Cooper pair box qubits through a\nnano-mechanical oscillator in a thermal state without using measurements in the\npresence of arbitrarily strong decoherence.",
        "positive": "Spinmotive force due to motion of magnetic bubble arrays driven by\n  magnetic field gradient: Interaction between local magnetization and conduction electrons is\nresponsible for a variety of phenomena in magnetic materials. It has been\nrecently shown that spin current and associated electric voltage can be induced\nby magnetization that depends on both time and space. This effect, called\nspinmotive force, provides for a powerful tool for exploring the dynamics and\nthe nature of magnetic textures, as well as a new source for electromotive\nforce. Here we theoretically demonstrate the generation of electric voltages in\nmagnetic bubble array systems subjected to a magnetic field gradient. It is\nshown by deriving expressions for the electric voltages that the present system\noffers a direct measure of phenomenological parameter that describes\nnon-adiabaticity in the current induced magnetization dynamics. This spinmotive\nforce opens a door for new types of spintronic devices that exploit the\nfield-gradient."
    },
    {
        "anchor": "Exciton spin dynamics and photoluminescence polarization of CdSe/CdS\n  dot-in-rod nanocrystals in high magnetic fields: The exciton spin dynamics and polarization properties of the related emission\nare investigated in colloidal CdSe/CdS dot-in-rod (DiR) and spherical\ncore/shell nanocrystal (NC) ensembles by magneto-optical photoluminescence (PL)\nspectroscopy in magnetic fields up to 15 T. It is shown that the degree of\ncircular polarization (DCP) of the exciton emission induced by the magnetic\nfield is affected by the NC geometry as well as the exciton fine structure and\ncan provide information on nanorod orientation. A theory to describe the\ncircular and linear polarization properties of the NC emission in magnetic\nfield is developed. It takes into account phonon mediated coupling between the\nexciton fine structure states as well as the dielectric enhancement effect\nresulting from the anisotropic shell of DiR NCs. This theoretical approach is\nused to model the experimental results and allows us to explain most of the\nmeasured features. The spin dynamics of the dark excitons is investigated in\nmagnetic fields by time-resolved photoluminescence. The results highlight the\nimportance of confined acoustic phonons in the spin relaxation of dark\nexcitons. The bare core surface as well as the core/shell interface give rise\nto an efficient spin relaxation channel, while the surface of core/shell NCs\nseems to play only a minor role.",
        "positive": "Unconventional topological phase transition in two-dimensional systems\n  with space-time inversion symmetry: We study a topological phase transition between a normal insulator and a\nquantum spin Hall insulator in two-dimensional (2D) systems with time-reversal\nand two-fold rotation symmetries. Contrary to the case of ordinary\ntime-reversal invariant systems where a direct transition between two\ninsulators is generally predicted, we find that the topological phase\ntransition in systems with an additional two-fold rotation symmetry is mediated\nby an emergent stable two-dimensional Weyl semimetal phase between two\ninsulators. Here the central role is played by the so-called space-time\ninversion symmetry, the combination of time-reversal and two-fold rotation\nsymmetries, which guarantees the quantization of the Berry phase around a 2D\nWeyl point even in the presence of strong spin-orbit coupling.\nPair-creation/pair-annihilation of Weyl points accompanying partner exchange\nbetween different pairs induces a jump of a 2D $Z_{2}$ topological invariant\nleading to a topological phase transition. According to our theory, the\ntopological phase transition in HgTe/CdTe quantum well structure is mediated by\na stable 2D Weyl semimetal phase since the quantum well, lacking inversion\nsymmetry intrinsically, has two-fold rotation about the growth direction.\nNamely, the HgTe/CdTe quantum well can show 2D Weyl semimetallic behavior\nwithin a small but finite interval in the thickness of HgTe layers between a\nnormal insulator and a quantum spin Hall insulator. We also propose that\nfew-layer black phosphorus under perpendicular electric field is another\ncandidate system to observe the unconventional topological phase transition\nmechanism accompanied by emerging 2D Weyl semimetal phase protected by\nspace-time inversion symmetry."
    },
    {
        "anchor": "Orbital Stark effect and quantum confinement transition of donors in\n  silicon: Adiabatic shuttling of single impurity bound electrons to gate induced\nsurface states in semiconductors has attracted much attention in recent times,\nmostly in the context of solid-state quantum computer architecture. A recent\ntransport spectroscopy experiment for the first time was able to probe the\nStark shifted spectrum of a single donor in silicon buried close to a gate.\nHere we present the full theoretical model involving large-scale quantum\nmechanical simulations that was used to compute the Stark shifted donor states\nin order to interpret the experimental data. Use of atomistic tight-binding\ntechnique on a domain of over a million atoms helped not only to incorporate\nthe full band structure of the host, but also to treat realistic device\ngeometries and donor models, and to use a large enough basis set to capture any\nnumber of donor states. The method yields a quantitative description of the\nsymmetry transition that the donor electron undergoes from a 3D Coulomb\nconfined state to a 2D surface state as the electric field is ramped up\nadiabatically. In the intermediate field regime, the electron resides in a\nsuperposition between the states of the atomic donor potential and that of the\nquantum dot like states at the surface. In addition to determining the effect\nof field and donor depth on the electronic structure, the model also provides a\nbasis to distinguish between a phosphorus and an arsenic donor based on their\nStark signature. The method also captures valley-orbit splitting in both the\ndonor well and the interface well, a quantity critical to silicon qubits. The\nwork concludes with a detailed analysis of the effects of screening on the\ndonor spectrum.",
        "positive": "Plasmon-enhanced nonlinear wave mixing in nanostructured graphene: Localized plasmons in metallic nanostructures have been widely used to\nenhance nonlinear optical effects due to their ability to concentrate and\nenhance light down to extreme-subwavelength scales. As alternatives to noble\nmetal nanoparticles, graphene nanostructures can host long-lived plasmons that\nefficiently couple to light and are actively tunable via electrical doping.\nHere we show that doped graphene nanoislands present unique opportunities for\nenhancing nonlinear optical wave-mixing processes between two externally\napplied optical fields at the nanoscale. These small islands can support\npronounced plasmons at multiple frequencies, resulting in extraordinarily high\nwave-mixing susceptibilities when one or more of the input or output\nfrequencies coincide with a plasmon resonance. By varying the doping charge\ndensity in a nanoisland with a fixed geometry, enhanced wave mixing can be\nrealized over a wide spectral range in the visible and near infrared. We\nconcentrate in particular on second- and third-order processes, including sum\nand difference frequency generation, as well as on four-wave mixing. Our\ncalculations for armchair graphene triangles composed of up to several hundred\ncarbon atoms display large wave mixing polarizabilities compared with metal\nnanoparticles of similar lateral size, thus supporting nanographene as an\nexcellent material for tunable nonlinear optical nanodevices."
    },
    {
        "anchor": "The Strong Sensitivity of the Characteristics of Binary Stochastic\n  Neurons Employing Low Barrier Nanomagnets to Small Geometrical Variations: Binary stochastic neurons (BSNs) are excellent activators for machine\nlearning. An ideal platform for implementing them are low- or\nzero-energy-barrier nanomagnets (LBMs) possessing in-plane anisotropy (e.g.\ncircular or slightly elliptical disks) whose fluctuating magnetization encodes\na probabilistic (p-) bit. Here, we show that such a BSN's activation function,\nthe pinning current (which pins the output to a particular binary state), and\nthe response time - all exhibit strong sensitivity to very slight geometric\nvariations in the LBM's cross section. A mere 1% change in the diameter of a\ncircular nanomagnet in any arbitrary direction can alter the response time by a\nfactor of ~4 at room temperature and a 10% change can alter the pinning current\nby a factor of ~2. All this causes large device-to-device variation which is\ndetrimental to integration.\n  We also show that the energy dissipation is lowered but the response time is\nincreased by replacing a circular cross-section with a slightly elliptical one\nand then encoding the p-bit in the magnetization component along the major\naxis. Encoding the p-bit in the magnetization component along the minor axis\nhas the opposite effect. The energy-delay-product, however, is relatively\nindependent of whether the cross-section is a circle or an ellipse and which\nmagnetization component encodes the p-bit in the case of the ellipse.",
        "positive": "A quantum fiber-pigtail: We present the experimental realization of a quantum fiber-pigtail. The\ndevice consists of a semiconductor quantum-dot embedded into a conical photonic\nwire that is directly connected to the core of a fiber-pigtail. We demonstrate\na photon collection efficiency at the output of the fiber of 5.8% and suggest\nrealistic improvements for the implementation of a useful device in the context\nof quantum information. We finally discuss potential applications in scanning\nprobe microscopy."
    },
    {
        "anchor": "Noise Suppression for Micromechanical Resonator via Intrinsic Dynamic\n  Feedback: We study a dynamic mechanism to passively suppress the thermal noise of a\nmicromechanical resonator through an intrinsic self-feedback that is genuinely\nnon-Markovian. We use two coupled resonators, one as the target resonator and\nthe other as an ancillary resonator, to illustrate the mechanism and its noise\nreduction effect. The intrinsic feedback is realized through the dynamics of\ncoupling between the two resonators: the motions of the target resonator and\nthe ancillary resonator mutually influence each other in a cyclic fashion.\nSpecifically, the states that the target resonator has attained earlier will\naffect the state it attains later due to the presence of the ancillary\nresonator. We show that the feedback mechanism will bring forth the effect of\nnoise suppression in the spectrum of displacement, but not in the spectrum of\nmomentum.",
        "positive": "Quantum Computational Gates with Radiation Free Couplings: We examine a generic three state mechanism which realizes all fundamental\nsingle and double qubit quantum logic gates operating under the effect of\nadiabatically controllable static (radiation free) bias couplings between the\nstates. At the instant of time that the gate operations are defined the third\nlevel is unoccupied which, in a certain sense, derives analogy with the\nrecently suggested dissipation free qubit subspaces. The physical\nimplementation of the mechanism is tentatively suggested in a form of the\nAharonov-Bohm persistent current loop in crossed electric and magnetic fields,\nwith the output of the loop read out by a (quantum) Hall effect aided\nmechanism."
    },
    {
        "anchor": "Solid-state quantum optics with quantum dots in photonic nanostructures: Quantum nanophotonics has become a new research frontier where quantum optics\nis combined with nanophotonics in order to enhance and control the interaction\nbetween strongly confined light and quantum emitters. Such progress provides a\npromising pathway towards quantum-information processing on an all-solid-state\nplatform. Here we review recent progress on experiments with single quantum\ndots in nanophotonic structures. Embedding the quantum dots in photonic\nband-gap structures offers a way of controlling spontaneous emission of single\nphotons to a degree that is determined by the local light-matter coupling\nstrength. Introducing defects in photonic crystals implies new functionalities.\nFor instance, efficient and strongly confined cavities can be constructed\nenabling cavity-quantum-electrodynamics experiments. Furthermore, the speed of\nlight can be tailored in a photonic-crystal waveguide forming the basis for\nhighly efficient single-photon sources where the photons are channeled into the\nslowly propagating mode of the waveguide. Finally, we will discuss some of the\nsurprises that arise in solid-state implementations of quantum-optics\nexperiments in comparison to their atomic counterparts. In particular, it will\nbe shown that the celebrated point-dipole description of light-matter\ninteraction can break down when quantum dots are coupled to plasmon\nnanostructures.",
        "positive": "Stripe formation driven by space noncommutativity in quantum Hall\n  systems: We propose that the transport anisotropy observed in half-filled high Landau\nlevels ($N \\geq 2$) is caused by the space noncommutativity effect, namely the\nHeisenberg uncertainty relation between the spatial coordinates of electrons.\nThe stripe corresponds to a limit that one coordinate of a large number of\nparticles is fixed at a certain value while its conjugate coordinate is\ncompletely uncertain. We make a renormalization group analysis and find that\nthe noncommutativity effect is able to drive the stripe formation only at\nhalf-fillings $\\nu = 9/2, 11/2, 13/2,$ etc., in agreement with experiments."
    },
    {
        "anchor": "Effect of electron-phonon coupling on energy and density of states\n  renormalizations of dynamically screened graphene: Electronic screening strongly renormalizes the linear bands which occur near\nthe Dirac crossing in graphene. The single bare Dirac crossing is split into\ntwo individual Dirac-like points, which are separated in energy but still at\nzero momentum relative to the K-point. A diamond-like structure occurs in\nbetween as a result of the formation of plasmarons. In this work we explore the\ncombined effect of electron-electron and electron-phonon coupling on the\nrenormalized energy dispersion, the spectral function and on the electronic\ndensity of states. We find that distinct signatures of the plasmaron structure\nare observable in the density of states with the split Dirac points presenting\nthemselves as minima with quadratic dependence on energy about such points. By\nexamining the slopes of both the density of states and the renormalized\ndispersion near the Fermi level, we illustrate how one can separate\n$k$-dependent and $\\omega$-dependent renormalizations and suggest how this\nmight allow for the isolation of the renormalization due to the electron-phonon\ninteraction from that of the electron-electron interaction.",
        "positive": "Ultrafast Response of Monolayer Molybdenum Disulfide (MoS2)\n  Photodetectors: The strong light emission and absorption exhibited by single atomic layer\ntransitional metal dichalcogenides in the visible to near-infrared wavelength\nrange makes them attractive for optoelectronic applications. In this work,\nusing two-pulse photovoltage correlation technique, we show that monolayer\nmolybdenum disulfide photodetector can have intrinsic response times as short\nas 3 ps implying photodetection bandwidths as wide as 300 GHz. The fast\nphotodetector response is a result of the short electron-hole and exciton\nlifetimes in this material. Recombination of photoexcited carriers in most\ntwo-dimensional metal dichalcogenides is dominated by non-radiative processes,\nmost notable among which is Auger scattering. The fast response time, and the\nease of fabrication of these devices, make them interesting for low-cost\nultrafast optical communication links."
    },
    {
        "anchor": "Avoided Band Crossing in Locally Periodic Elastic Rods: Avoided band crossings have been studied theoretically and it has been shown\nthat they can provide a tunning of the metal-insulator transition. Here we\npresent an experimental example of an avoided band crossing for a classical\nundulatory system: torsional waves in locally periodic rods. To excite and\ndetect the torsional waves, an electromagnetic-acoustic transducer for\nlow-frequencies that we have recently developed, is used. Calculations\nperformed using the transfer matrix method agree with the experimental\nmeasurements. In the observed avoided band crossing one level, which is a\nborder-induced bulk level, moves from one band to the next.",
        "positive": "Double Dirac Cones and Topologically Non-Trivial Phonons for Continuous,\n  Square Symmetric (C$_{4v}$ and C$_{2v}$) Unit Cells: Because phononic topological insulators have primarily been studied in\ndiscrete, graphene-like structures with C$_{6}$ or C$_{3}$ hexagonal symmetry,\nan open question is how to systematically achieve double Dirac cones and\ntopologically non-trivial structures using continuous, non-hexagonal unit\ncells. Here, we address this challenge by presenting a novel computational\nmethodology for the inverse design of continuous two-dimensional square\nphononic metamaterials exhibiting C$_{4v}$ and C$_{2v}$ symmetry. This leads to\nthe systematic design of square unit cell topologies exhibiting a double Dirac\ndegeneracy, which enables topologically-protected interface propagation based\non the quantum spin Hall effect (QSHE). Numerical simulations prove that\nhelical edge states emerge at the interface between two topologically distinct\nsquare phononic metamaterials, which opens the possibility of QSHE-based\npseudospin-dependent transport beyond hexagonal lattices."
    },
    {
        "anchor": "Thermal Probing of Energy Dissipation in Current-Carrying Carbon\n  Nanotubes: The temperature distributions in current-carrying carbon nanotubes have been\nmeasured with a scanning thermal microscope. The obtained temperature profiles\nreveal diffusive and dissipative electron transport in multi-walled nanotubes\nand in single-walled nanotubes when the voltage bias was higher than the\n0.1-0.2 eV optical phonon energy. Over ninety percent of the Joule heat in a\nmulti-walled nanotube was found to be conducted along the nanotube to the two\nmetal contacts. In comparison, about eighty percent of the Joule heat was\ntransferred directly across the nanotube-substrate interface for single-walled\nnanotubes. The average temperature rise in the nanotubes is determined to be in\nthe range of 5 to 42 K per micro watt Joule heat dissipation in the nanotubes.",
        "positive": "Higher-order Fermi-liquid corrections for an Anderson impurity away from\n  half-filling III: non-equilibrium transport: We extend the microscopic Fermi-liquid theory for the Anderson impurity\n[Phys.\\ Rev.\\ B {\\bf 64}, 153305 (2001)] to explore non-equilibrium transport\nat finite magnetic fields. Using the Ward identities in the Keldysh formalism\nwith the analytic and anti-symmetric properties of the vertex function, the\nspin-dependent Fermi-liquid corrections of order $T^2$ and $(eV)^2$ are\ndetermined at low temperatures $T$ and low bias voltages $eV$. Away from\nhalf-filling, these corrections can be expressed in terms of the linear and\nnon-linear static susceptibilities which represent the two-body and three-body\nfluctuations, respectively. We calculate the non-linear susceptibilities using\nthe numerical renormalization group, to explore the differential conductance\n$dI/dV$ through a quantum dot. We find that the two-body fluctuations dominate\nthe corrections in the Kondo regime at zero magnetic field. The contribution of\nthe three-body fluctuations become significant far away from half-filling,\nespecially in the valence-fluctuation regime and empty-orbital regimes. In\nfinite magnetic fields, the three-body contributions become comparable to the\ntwo-body contributions, and play an essential role in the splitting of the\nzero-bias conductance peak occurring at a magnetic field of the order of the\nKondo energy scale. We also apply our microscopic formulation to the\nmagneto-resistance and thermal conductivity of dilute magnetic alloys away from\nhalf-filling."
    },
    {
        "anchor": "Tuning electron correlation in magic-angle twisted bilayer graphene\n  using Coulomb screening: The ability to control the strength of interaction is essential for studying\nquantum phenomena emerging from a system of correlated fermions. For example,\nthe isotope effect illustrates the effect of electron-phonon coupling on\nsuperconductivity, providing an important experimental support for the BCS\ntheory. In this work, we report a new device geometry where the magic-angle\ntwisted bilayer graphene (tBLG) is placed in close proximity to a Bernal\nbilayer graphene (BLG) separated by a 3 nm thick barrier. Using charge\nscreening from the Bernal bilayer, the strength of electron-electron Coulomb\ninteraction within the twisted bilayer can be continuously tuned. Transport\nmeasurements show that tuning Coulomb screening has opposite effect on the\ninsulating and superconducting states: as Coulomb interaction is weakened by\nscreening, the insulating states become less robust, whereas the stability of\nsuperconductivity is enhanced. Out results demonstrate the ability to directly\nprobe the role of Coulomb interaction in magic-angle twisted bilayer graphene.\nMost importantly, the effect of Coulomb screening points toward electron-phonon\ncoupling as the dominant mechanism for Cooper pair formation, and therefore\nsuperconductivity, in magic-angle twisted bilayer graphene.",
        "positive": "Spin relaxation due to electron-electron magnetic interaction in high\n  Lande g-factor semiconductors: We investigate spin transport in InSb/InAlSb heterostructure using the Monte\nCarlo approach, generalized by including density matrix description of spin for\ntaking spin dynamics into account. In addition to the dominant Dyakonov-Perel\n(DP) mechanism for spin control and relaxation, we consider magnetic\ninteraction between electrons which assumes importance due to high electronic\nLande g-factor in the material. It is found that while the effect of magnetic\ninteraction is not important at low densities, it reduces the spin relaxation\nlength by as much as 50% at higher densities. We also present a calculation\nwhich elucidates the suppression of decoherence attributed to wave vector\ndependent magnetic field in the DP relaxation mechanism. We note that magnetic\ninteraction is a general relaxation mechanism which may assume importance in\nmaterials with high electronic Lande g-factor."
    },
    {
        "anchor": "Non-Hermitian Floquet topological phases: Exceptional points, coalescent\n  edge modes, and the skin effect: Periodically driven non-Hermitian systems can exhibit rich topological band\nstructure and non-Hermitian skin effect, without analogs in their static or\nHermitian counterparts. In this work we investigate the exceptional\nband-touching points in the Floquet quasi-energy bands, the topological\ncharacterization of such exceptions points and the Floquet non-Hermitian skin\neffect (FNHSE). Specifically, we exploit the simplicity of periodically\nquenched two-band systems in one dimension or two dimensions to analytically\nobtain the Floquet effective Hamiltonian as well as locations of the many\nexceptional points possessed by the Floquet bulk bands. Two different types of\ntopological winding numbers are used to characterize the topological features.\nBulk-edge correspondence (BBC) is naturally found to break down due to FNHSE,\nwhich can be drastically different among different bulk states. Remarkably,\ngiven the simple nature of our model systems, recovering the BBC is doable in\npractice only for certain parameter regime where a low-order truncation of the\ncharacteristic polynomial (which determines the Floquet band structure) becomes\nfeasible. Furthermore, irrespective of which parameter regime we work with, we\nfind a number of intriguing aspects of Floquet topological zero modes and $\\pi$\nmodes. For example, under the open boundary condition zero edge modes and $\\pi$\nedge modes can individually coalesce and localize at two different boundaries.\nThese anomalous edge states can also switch their accumulation boundaries when\ncertain system parameter is tuned. These results indicate that non-Hermitian\nFloquet topological phases, though more challenging to understand than their\nHermitian counterparts, can be extremely rich in the presence of FNHSE.",
        "positive": "Spin-orbit torque characterization in a nutshell: Spin current and spin torque generation through the spin-orbit interactions\nin solids, of bulk or interfacial origin, is at the heart of spintronics\nresearch. The realization of spin-orbit torque (SOT) driven magnetic dynamics\nand switching in diverse magnetic heterostructures also pave the way for\ndeveloping SOT magnetoresistive random access memory and other novel SOT memory\nand logic devices. Of scientific and technological importance are accurate and\nefficient SOT quantification techniques, which have been abundantly developed\nin the last decade. In this article, we summarize popular techniques to\nexperimentally quantify SOTs in magnetic heterostructures at micro- and\nnano-scale. For each technique, we give an overview of its principle,\nvariations, strengths, shortcomings, error sources, and any cautions in usage.\nFinally, we discuss the remaining challenges in understanding and quantifying\nthe SOTs in heterostructures."
    },
    {
        "anchor": "Optical emission spectroscopy study of competing phases of electrons in\n  the second Landau level: Quantum phases of electrons in the filling factor range $2 \\leq\\nu\\leq 3$ are\nprobed by the weak optical emission from the partially populated second Landau\nlevel and spin wave measurements. Observations of optical emission include a\nmultiplet of sharp peaks that exhibit a strong filling factor dependence. Spin\nwave measurements by resonant inelastic light scattering probe breaking of spin\nrotational invariance and are used to link this optical emission with\ncollective phases of electrons. A remarkably rapid interplay between emission\npeak intensities manifests phase competition in the second Landau level.",
        "positive": "DECaNT: Simulation Tool for Diffusion of Excitons in Carbon Nanotube\n  Films: We present the numerical tool DECaNT (Diffusion of Excitons in Carbon\nNanoTubes) that simulates exciton transport in thin films of carbon nanotubes.\nThrough a mesh of nanotubes generated using the Bullet Physics C++ library,\nexcitons move according to an ensemble Monte Carlo algorithm, with the\nscattering rates that account for tube chirality, orientation, and distance. We\ncalculate the diffusion tensor from the position--position correlation\nfunctions and analyze its anisotropy and dependence on the film composition,\nmorphology, and defect density."
    },
    {
        "anchor": "From Coupled Rashba Electron and Hole Gas Layers to 3D Topological\n  Insulators: We introduce a system of stacked two-dimensional electron and hole gas layers\nwith Rashba spin orbit interaction and show that the tunnel coupling between\nthe layers induces a strong three- dimensional (3D) topological insulator\nphase. At each of the two-dimensional bulk boundaries we find the spectrum\nconsisting of a single anistropic Dirac cone, which we show by analytical and\nnumerical calculations. Our setup has a unit-cell consisting of four tunnel\ncoupled Rashba layers and presents a synthetic strong 3D topological insulator\nand is distinguished by its rather high experimental feasibility.",
        "positive": "Klein Factors in multiple Fractional Quantum Hall edge tunneling: A fractional quantum Hall liquid with multiple edges is considered. The\ncomputation of transport quantities such as current, noise and noise cross\ncorrelations in such multiple edge samples requires the implementation of so\ncalled Klein factors, which insure the correct quasiparticle exchange\nproperties. The commutation relations of these factors are obtained by closing\nthe system into a single edge. The non-equilibrium Green's function formalism\nassociated with such factors is derived for a simple Laughlin fraction of the\nHall effect. It is shown explicitly how Klein factors enter the calculation of\nthe noise cross correlations, as well as the correction to the Poisson limit\nfor the noise."
    },
    {
        "anchor": "Comments on the continuing widespread and unnecessary use of a defective\n  emission equation in field emission related literature: Field electron emission (FE) has relevance in many different technological\ncontexts. However, many related technological papers use a physically defective\nelementary FE equation for local emission current density (LECD). This equation\ntakes the tunneling barrier as exactly triangular, as in the original FE theory\nof 90 years ago. More than 60 years ago, it was shown that the so-called\nSchottky-Nordheim (SN) barrier, which includes an image-potential-energy term\n(that models exchange-and-correlation effects) is better physics. For a\nmetal-like emitter with work-function 4.5 eV, the SN-barrier-related\nMurphy-Good FE equation predicts LECD values that are higher than the\nelementary equation values by a large factor, often between around 250 and\naround 500. By failing to mention/apply this 60-year-old established science,\nor to inform readers of the large errors associated with the elementary\nequation, many papers (aided by defective reviewing) spread a new kind of\n\"pathological science\", and create a modern research-integrity problem. The\npresent paper aims to enhance author and reviewer awareness by summarizing\nrelevant aspects of FE theory, by explicitly identifying the misjudgment in the\noriginal 1928 Fowler-Nordheim paper, by explicitly calculating the size of the\nresulting error, and by showing in detail why most FE theoreticians regard the\n1950s modifications as better physics. Suggestions are made, about nomenclature\nand about citation practice, that may help to diminish misunderstandings.",
        "positive": "Topological $\u03c0$-junctions from crossed Andreev reflection in the\n  Quantum Hall regime: We consider a two-dimensional electron gas (2DEG) in the Quantum Hall regime\nin the presence of a Zeeman field, with the Fermi level tuned to filling factor\n$\\nu=1$. We show that, in the presence of spin-orbit coupling, contacting the\n2DEG to a narrow strip of an s-wave superconductor produces a topological\nsuperconducting gap along the contact as a result of crossed Andreev reflection\n(CAR) processes across the strip. The sign of the topological gap, controlled\nby the CAR amplitude, depends periodically on the Fermi wavelength and strip\nwidth and can be externally tuned. An interface between two halves of a long\nstrip with topological gaps of opposite sign implements a robust\n$\\pi$-junction, hosting a pair of Majorana zero modes that do not split despite\ntheir overlap. We show that such a situation can be exploited to perform\nprotected non-Abelian tunnel-braid operations without any fine tuning."
    },
    {
        "anchor": "Hotspots in two-phase conducting media: We study electric properties of random resistor networks consisting of\nresistors of two kinds numerically, focusing on the power loss across each\nbond. Tuning the ratio of the resistances $r$ and their respective fraction\n$\\alpha$ we find that at large $r$ the conductance of the network is dominated\nby a few optimal, percolation-like, conducting paths. We demonstrate that the\ndistribution of the local power losses $P$ is exponential,\n$\\propto\\exp(-P/\\langle P\\rangle)$, and reveal the spatial distribution of\nhotspots concentrating the main part of the dissipated power.",
        "positive": "Inter-quintuple layer coupling and topological phase transitions in the\n  chalcogenide topological insulators: Driving quantum phase transitions in the 3D topological insulators offers\npathways to tuning the topological states and their properties. We use\nDFT-based calculations to systematically investigate topological phase\ntransitions in Bi$_2$Se$_3$, Sb$_2$Se$_3$, Bi$_2$Te$_3$ and Sb$_2$Te$_3$ by\nvarying the $c/a$ ratio of lattice constants. This ensures no net hydrostatic\npressure under anisotropic stress and strain and allows a clear identification\nof the physics leading to the transition. As a function of $c/a$, all of these\nmaterials exhibit structural and electronic stability of the quintuple layers\n(QLs), and quasi-linear behavior of both the inter-quintuple layer distance and\nthe energy gap near the topological transition. Our results show that the\ntransition is predominantly controlled by the inter-QL physics, namely by\ncompeting Coulomb and van der Waals interactions between the outer atomic\nsheets in neighboring quintuple layers. We discuss the implications of our\nresults for topological tuning by alloying."
    },
    {
        "anchor": "Curved Graphene Nanoribbons: Structure and Dynamics of Carbon Nanobelts: Carbon nanoribbons (CNRs) are graphene (planar) structures with large aspect\nratio. Carbon nanobelts (CNBs) are small graphene nanoribbons rolled up into\nspiral-like structures, i. e., carbon nanoscrolls (CNSs) with large aspect\nratio. In this work we investigated the energetics and dynamical aspects of\nCNBs formed from rolling up CNRs. We have carried out molecular dynamics\nsimulations using reactive empirical bond-order potentials. Our results show\nthat similarly to CNSs, CNBs formation is dominated by two major energy\ncontribution, the increase in the elastic energy due to the bending of the\ninitial planar configuration (decreasing structural stability) and the\nenergetic gain due to van der Waals interactions of the overlapping surface of\nthe rolled layers (increasing structural stability). Beyond a critical diameter\nvalue these scrolled structures can be even more stable (in terms of energy)\nthan their equivalent planar configurations. In contrast to CNSs that require\nenergy assisted processes (sonication, chemical reactions, etc.) to be formed,\nCNBs can be spontaneously formed from low temperature driven processes. Long\nCNBs (length of $\\sim$ 30.0 nm) tend to exhibit self-folded racket-like\nconformations with formation dynamics very similar to the one observed for long\ncarbon nanotubes. Shorter CNBs will be more likely to form perfect scrolled\nstructures. Possible synthetic routes to fabricate CNBs from graphene membranes\nare also addressed.",
        "positive": "Leakage Current of a Superconductor-Normal Metal Tunnel Junction\n  Connected to a High-Temperature Environment: We consider a voltage-biased Normal metal-Insulator-Superconductor (NIS)\ntunnel junction, connected to a high-temperature external electromagnetic\nenvironment. This model system features the commonly observed subgap leakage\ncurrent in NIS junctions through photon-assisted tunneling which is detrimental\nfor applications. We first consider a NIS junction directly coupled to the\nenvironment and analyze the subgap leakage current both analytically and\nnumerically; we discuss the link with the phenomenological Dynes parameter.\nThen we focus on a circuit where a low-temperature lossy transmission line is\ninserted between the NIS junction and the environment. We show that the subgap\nleakage current is exponentially suppressed as the length, $\\ell$, and the\nresistance per unit length, $R_0$, of the line are increased. We finally\ndiscuss our results in view of the performance of NIS junctions in\napplications."
    },
    {
        "anchor": "Zero-bias anomaly in two-dimensional electron layers and multiwall\n  nanotubes: The zero-bias anomaly in the dependence of the tunneling density of states\n$\\nu (\\epsilon)$ on the energy $\\epsilon$ of the tunneling particle for two-\nand one-dimensional multilayered structures is studied. We show that for a\nballistic two-dimensional (2D) system the first order interaction correction to\nDOS due to the plasmon excitations studied by Khveshchenko and Reizer is partly\ncompensated by the contribution of electron-hole pairs which is twice as small\nand has the opposite sign. For multilayered systems the total correction to the\ndensity of states near the Fermi energy has the form $\\delta \\nu/\\nu_0 = {max}\n(| \\epsilon |, \\epsilon^*)/4\\epsilon_F$, where $\\epsilon^*$ is the plasmon\nenergy gap of the multilayered 2D system. In the case of one-dimensional\nconductors we study multiwall nanotubes with the elastic mean free path\nexceeding the radius of the nanotube. The dependence of the tunneling density\nof states energy, temperature and on the number of shells is found.",
        "positive": "Quasicrystalline electronic states in twisted bilayers and the effects\n  of interlayer and sublattice symmetries: We study the electronic structure of quasicrystals composed of incommensurate\nstacks of atomic layers. We consider two systems: a pair of square lattices\nwith a relative twist angle of $\\theta=45^\\circ$ and a pair of hexagonal\nlattices with a relative twist angle of $\\theta=30^\\circ$, with various\ninterlayer interaction strengths. This constitutes every two-dimensional\nbilayer quasicrystal system. We investigate the resonant coupling governing the\nquasicrystalline order in each quasicrystal symmetry, and calculate the\nquasi-band dispersion. The resonant interaction emerges in bilayer\nquasicrystals if all the dominant interlayer interactions occur between the\natomic orbitals that have the same magnetic quantum number. Thus, not only the\nquasicrystal composed of the widely studied graphene, but also those composed\nof transition metal dichalcogenides will exhibit the quasicrystalline states.\nWe find that some quasicrystalline states, which are usually obscured by\ndecoupled monolayer states, are more prominent, i.e., \"exposed\", in the systems\nwith strong interlayer interaction. We also show that we can switch the states\nbetween quasicrystalline configuration and its layer components, by turning on\nand off the interlayer symmetry."
    },
    {
        "anchor": "Magnon based logic in a multi-terminal YIG/Pt nanostructure: Boolean logic is the foundation of modern digital information processing.\nRecently, there has been a growing interest in phenomena based on pure spin\ncurrents, which allow to move from charge to spin based logic gates. We study a\nproof-of-principle logic device based on the ferrimagnetic insulator Yttrium\nIron Garnet (YIG), with Pt strips acting as injectors and detectors for\nnonequilibrium magnons. We experimentally observe incoherent superposition of\nmagnons generated by different injectors. This allows to implement a fully\nfunctional majority gate, enabling multiple logic operations (AND and OR) in\none and the same device. Clocking frequencies of the order of several GHz and\nstraightforward down-scaling make our device promising for applications.",
        "positive": "Nonlinear relaxation between magnons and phonons in insulating\n  ferromagnets: Nonlinear relaxation between spin waves (magnons) and the crystal lattice\n(phonons) in an insulating ferromagnet is investigated theoretically. Magnons\nand phonons are described by the equilibrium Bose-Einstein distributions with\ndifferent temperatures. The nonlinear heat current from magnons to phonons is\ncalculated microscopically in terms of the Cherenkov radiation of phonons by\nmagnons. The results are discussed in comparison with the well-known\ntheoretical results on the nonlinear electron-phonon relaxation in metals\n[Kaganov, Lifshitz, Tanatarov, J. Exp. Theor. Phys. 31, 232 (1956)]. The\nelaborated theoretical description is relevant for spin-pumping experiments and\nthermoelectric devices in which the magnon temperature is essentially higher\nthan the phonon one."
    },
    {
        "anchor": "Bosonization out of equilibrium: We develop a bosonization technique for one-dimensional fermions out of\nequilibrium. The approach is used to study a quantum wire attached to two\nelectrodes with arbitrary energy distributions. The non-equilibrium electron\nGreen function is expressed in terms of functional determinants of a\nsingle-particle``counting'' operator with a time-dependent scattering phase.\nThe result reveals an intrinsic relation of dephasing and energy redistribution\nin Luttinger-liquids to ``fractionalization'' of electron-hole excitations in\nthe tunneling process and at boundaries with leads.",
        "positive": "Large conduction band and Fermi velocity spin splittings due to Coulomb\n  interactions in single-layer MoS_{2}: We study the effect of Coulomb interactions on the low energy band structure\nof single-layer transition metal dichalcogenide semiconductors using an\neffective low energy model. We show how a large conduction band spin splitting\nand a spin dependent Fermi velocity are generated in MoS$_2$, as a consequence\nof the difference between the gaps of the two spin projections induced by the\nspin-orbit interaction. The conduction band and Fermi velocity spin splittings\nfound are in agreement with the optical absorption energies of the excitonic\npeaks A, B measured in the experiments."
    },
    {
        "anchor": "Mapping universal conductance fluctuations: Graphene provides a fascinating testbed for new physics and exciting\nopportunities for future applications based on quantum phenomena. To understand\nthe coherent flow of electrons through a graphene device, we employ a nanoscale\nprobe that can access the relevant length scales - the tip of a\nliquid-He-cooled scanning probe microscope (SPM) capacitively couples to the\ngraphene device below, creating a movable scatterer for electron waves. At\nsufficiently low temperatures and small size scales, the diffusive transport of\nelectrons through graphene becomes coherent, leading to universal conductance\nfluctuations (UCF). By scanning the tip over a device, we map these conductance\nfluctuations \\textit{vs.} scatterer position. We find that the conductance is\nhighly sensitive to the tip position, producing $\\delta G \\sim e^2/h$\nfluctuations when the tip is displaced by a distance comparable to half the\nFermi wavelength. These measurements are in good agreement with detailed\nquantum simulations of the imaging experiment, and demonstrate the value of a\ncooled SPM for probing coherent transport in graphene.",
        "positive": "Signatures of exchange correlations in the thermopower of quantum dots: We use a many-body rate-equation approach to calculate the thermopower of a\nquantum dot in the presence of an exchange interaction. At temperatures much\nsmaller than the single-particle level spacing, the known quantum jumps\n(discontinuities) in the thermopower are split by the exchange interaction. The\norigin and nature of the splitting are elucidated with a simple physical\nargument based on the nature of the intermediate excited state in the\nsequential tunneling approach. We show that this splitting is sensitive to the\nnumber parity of electrons in the dot and the dot's ground-state spin. These\neffects are suppressed when cotunneling dominates the electrical and thermal\nconductances. We calculate the thermopower in the presence of elastic\ncotunneling, and show that some signatures of exchange correlations should\nstill be observed with current experimental methods. In particular, we propose\na method to determine the strength of the exchange interaction from\nmeasurements of the thermopower."
    },
    {
        "anchor": "Liquid-activated quantum emission from pristine hexagonal boron nitride\n  for nanofluidic sensing: Liquids confined down to the atomic scale can show radically new properties.\nHowever, only indirect and ensemble measurements operate in such extreme\nconfinement, calling for novel optical approaches enabling direct imaging at\nthe molecular level. Here, we harness fluorescence originating from\nsingle-photon emitters at the surface of hexagonal boron nitride (hBN) for\nmolecular imaging and sensing in nanometrically confined liquids. The emission\noriginates from the chemisorption of organic solvent molecules onto native\nsurface defects, revealing single-molecule dynamics at the interface through\nspatially correlated activation of neighboring defects. Emitter spectra further\noffer a direct readout of local dielectric properties, unveiling increasing\ndielectric order under nanometer-scale confinement. Liquid-activated native hBN\ndefects bridge the gap between solid-state nanophotonics and nanofluidics,\nopening new avenues for nanoscale sensing and optofluidics.",
        "positive": "Spin Seebeck effect of correlated magnetic molecules: In this paper we investigate the spin-resolved thermoelectric properties of\nstrongly correlated molecular junctions in the linear response regime. The\nmagnetic molecule is modeled by a single orbital level to which the molecular\ncore spin is attached by an exchange interaction. Using the numerical\nrenormalization group method we analyze the behavior of the (spin) Seebeck\neffect, heat conductance and figure of merit for different model parameters of\nthe molecule. We show that the thermopower strongly depends on the strength and\ntype of the exchange interaction as well as the molecule's magnetic anisotropy.\nWhen the molecule is coupled to ferromagnetic leads, the thermoelectric\nproperties reveal an interplay between the spin-resolved tunneling processes\nand intrinsic magnetic properties of the molecule. Moreover, in the case of\nfinite spin accumulation in the leads, the system exhibits the spin Seebeck\neffect. We demonstrate that a considerable spin Seebeck effect can develop when\nthe molecule exhibits an easy-plane magnetic anisotropy, while the sign of the\nspin thermopower depends on the type and magnitude of the molecule's exchange\ninteraction."
    },
    {
        "anchor": "The Kondo Effect in the Presence of Magnetic Impurities: We measure transport through gold grain quantum dots fabricated using\nelectromigration, with magnetic impurities in the leads. A Kondo interaction is\nobserved between dot and leads, but the presence of magnetic impurities results\nin a gate-dependent zero-bias conductance peak that is split due to an RKKY\ninteraction between the spin of the dot and the static spins of the impurities.\nA magnetic field restores the single Kondo peak in the case of an\nantiferromagnetic RKKY interaction. This system provides a new platform to\nstudy Kondo and RKKY interactions in metals at the level of a single spin.",
        "positive": "Finite size effects in the magnetization of periodic mesoscopic systems: We calculate the orbital magnetization of a confined 2DEG as a function of\nthe number of electrons in the system. Size effects are investigated by\nsystematically increasing the area of the confining region. The results for the\nfinite system are compared to an infinite one, where the magnetization is\ncalculated in the thermodynamic limit. In all calculations the\nelectron-electron interaction is included in the Hartree approximation."
    },
    {
        "anchor": "Quantum Dynamics of Spins Coupled by Electrons in 1D Channel: We develop a unified theoretical description of the induced interaction and\nquantum noise in a system of two spins (qubits) coupled via a\nquasi-one-dimensional electron gas in the Luttinger liquid regime. Our results\nallow evaluation of the degree of coherence in quantum dynamics driven by the\ninduced indirect exchange interaction of localized magnetic moments due to\nconduction electrons, in channel geometries recently experimentally studied for\nqubit control and measurement.",
        "positive": "Multi-domain electromagnetic absorption of triangular quantum rings: We present a theoretical study of the unielectronic energy spectra, electron\nlocalization, and optical absorption of triangular core-shell quantum rings. We\nshow how these properties depend on geometric details of the triangle, such as\nside thickness or corners' symmetry. For equilateral triangles, the lowest six\nenergy states (including spin) are grouped in an energy shell, are localized\nonly around corner areas, and are separated by a large energy gap from the\nstates with higher energy which are localized on the sides of the triangle. The\nenergy levels strongly depend on the aspect ratio of the triangle sides, i.e.,\nthickness/length ratio, in such a way that the energy differences are not\nmonotonous functions of this ratio. In particular, the energy gap between the\ngroup of states localized in corners and the states localized on the sides\nstrongly decreases with increasing the side thickness, and then slightly\nincreases for thicker samples. With increasing the thickness the low-energy\nshell remains distinct but the spatial distribution of these states spreads.\nThe behavior of the energy levels and localization leads to a thickness\ndependent absorption spectrum where one transition may be tuned in the THz\ndomain and a second transition can be tuned from THz to the infrared range of\nelectromagnetic spectrum. We show how these features may be further controlled\nwith an external magnetic field. In this work the electron-electron Coulomb\nrepulsion is neglected."
    },
    {
        "anchor": "Dual approach to circuit quantization using loop charges: The conventional approach to circuit quantization is based on node fluxes and\ntraces the motion of node charges on the islands of the circuit. However, for\nsome devices, the relevant physics can be best described by the motion of\npolarization charges over the branches of the circuit that are in general\nrelated to the node charges in a highly nonlocal way. Here, we present a\nmethod, dual to the conventional approach, for quantizing planar circuits in\nterms of loop charges. In this way, the polarization charges are directly\nobtained as the differences of the two loop charges on the neighboring loops.\nThe loop charges trace the motion of fluxes through the circuit loops. We show\nthat loop charges yield a simple description of the flux transport across\nphase-slip junctions. We outline a concrete construction of circuits based on\nphase-slip junctions that are electromagnetically dual to arbitrary planar\nJosephson junction circuits. We argue that loop charges also yield a simple\ndescription of the flux transport in conventional Josephson junctions shunted\nby large impedances. We show that a mixed circuit description in terms of node\nfluxes and loop charges yields an insight into the flux decompactification of a\nJosephson junction shunted by an inductor. As an application, we show that the\nfluxonium qubit is well approximated as a phase-slip junction for the\nexperimentally relevant parameters. Moreover, we argue that the $0$-$\\pi$ qubit\nis effectively the dual of a Majorana Josephson junction.",
        "positive": "Modulation of the high mobility two-dimensional electrons in Si/SiGe\n  using atomic-layer-deposited gate dielectric: Metal-oxide-semiconductor field-effect transistors (MOSFET's) using\natomic-layer-deposited (ALD) Al$_2$O$_3$ as the gate dielectric are fabricated\non the Si/Si$_{1-x}$Ge$_x$ heterostructures. The low-temperature carrier\ndensity of a two-dimensional electron system (2DES) in the strained Si quantum\nwell can be controllably tuned from 2.5$\\times10^{11}$cm$^{-2}$ to\n4.5$\\times10^{11}$cm$^{-2}$, virtually without any gate leakage current.\nMagnetotransport data show the homogeneous depletion of 2DES under gate biases.\nThe characteristic of vertical modulation using ALD dielectric is shown to be\nbetter than that using Schottky barrier or the SiO$_2$ dielectric formed by\nplasma-enhanced chemical-vapor-deposition(PECVD)."
    },
    {
        "anchor": "Tuning of quantum interference in top-gated graphene on SiC: We report on quantum-interference measurements in top-gated Hall bars of\nmonolayer graphene epitaxially grown on the Si face of SiC, in which the\ntransition from negative to positive magnetoresistance was achieved varying\ntemperature and charge density. We perform a systematic study of the quantum\ncorrections to the magnetoresistance due to quantum interference of\nquasiparticles and electron-electron interaction. We analyze the contribution\nof the different scattering mechanisms affecting the magnetotransport in the\n$-2.0 \\times 10^{10}$ cm$^{-2}$ to $3.75 \\times 10^{11}$ cm$^{-2}$ density\nregion and find a significant influence of the charge density on the\nintravalley scattering time. Furthermore, we observe a modulation of the\nelectron-electron interaction with charge density not accounted for by present\ntheory. Our results clarify the role of quantum transport in SiC-based devices,\nwhich will be relevant in the development of a graphene-based technology for\ncoherent electronics.",
        "positive": "Dynamical classification of topological quantum phases: Topological phase of matter is now a mainstream of research in condensed\nmatter physics, of which the classification, synthesis, and detection of\ntopological states have brought excitements over the recent decade while remain\nincomplete with ongoing challenges in both theory and experiment. Here we\npropose to establish a universal dynamical characterization of the topological\nquantum phases classified by integers, and further propose the high-precision\ndynamical schemes to detect such states. The framework of {the dynamical\nclassification theory} consists of basic theorems. First, we uncover that\nclassifying a $d$-dimensional ($d$D) gapped topological phase {of generic\nmultibands} can reduce to a ($d-1$)D invariant defined on so-called band\ninversion surfaces (BISs), rendering a {\\it bulk-surface duality} which\nsimplifies the topological characterization. Further, we show in quenching\nacross phase boundary the (pseudo)spin dynamics to exhibit unique topological\npatterns on BISs, which are attributed to the post-quench bulk topology and\nmanifest a {\\it dynamical bulk-surface correspondence}. For this the\ntopological phase is classified by a dynamical topological invariant measured\nfrom dynamical spin-texture field on the BISs. Applications to quenching\nexperiments on feasible models are proposed and studied, demonstrating the new\nexperimental strategies to detect topological phases with high feasibility.\nThis work opens a broad new direction to classify and detect topological phases\nby quantum dynamics."
    },
    {
        "anchor": "Quantum Hall effect and Landau level crossing of Dirac fermions in\n  trilayer graphene: We investigate electronic transport in high mobility (\\textgreater 100,000\ncm$^2$/V$\\cdot$s) trilayer graphene devices on hexagonal boron nitride, which\nenables the observation of Shubnikov-de Haas oscillations and an unconventional\nquantum Hall effect. The massless and massive characters of the TLG subbands\nlead to a set of Landau level crossings, whose magnetic field and filling\nfactor coordinates enable the direct determination of the\nSlonczewski-Weiss-McClure (SWMcC) parameters used to describe the peculiar\nelectronic structure of trilayer graphene. Moreover, at high magnetic fields,\nthe degenerate crossing points split into manifolds indicating the existence of\nbroken-symmetry quantum Hall states.",
        "positive": "Phase preserving amplification near the quantum limit with a Josephson\n  Ring Modulator: Recent progress in solid state quantum information processing has stimulated\nthe search for ultra-low-noise amplifiers and frequency converters in the\nmicrowave frequency range, which could attain the ultimate limit imposed by\nquantum mechanics. In this article, we report the first realization of an\nintrinsically phase-preserving, non-degenerate superconducting parametric\namplifier, a so far missing component. It is based on the Josephson ring\nmodulator, which consists of four junctions in a Wheatstone bridge\nconfiguration. The device symmetry greatly enhances the purity of the\namplification process and simplifies both its operation and analysis. The\nmeasured characteristics of the amplifier in terms of gain and bandwidth are in\ngood agreement with analytical predictions. Using a newly developed noise\nsource, we also show that our device operates within a factor of three of the\nquantum limit. This development opens new applications in the area of quantum\nanalog signal processing."
    },
    {
        "anchor": "Ab initio study of charge transport through single oxygen molecules in\n  atomic aluminum contacts: We present ab initio calculations of transport properties of atomic-sized\naluminum contacts in the presence of oxygen. The experimental situation is\nmodeled by considering a single oxygen atom (O) or one of the molecules O2 and\nO3 bridging the gap between electrodes forming ideal, atomically sharp\npyramids. The transport characteristics are computed for these geometries with\nincreasing distances between the leads, simulating the opening of a break\njunction. To facilitate comparison with experiments further, the vibrational\nmodes of the oxygen connected to the electrodes are studied. It is found that\nin the contact regime the change of transport properties due to the presence of\noxygen is strong and should be detectable in experiments. All three types of\noxygen exhibit a comparable behavior in their vibrational frequencies and\nconductances, which are well below the conductance of pure aluminum atomic\ncontacts. The conductance decreases for an increasing number of oxygen atoms.\nIn the tunneling regime the conductance decays exponentially with distance and\nthe decay length depends on whether or not oxygen is present in the junction.\nThis fact may provide a way to identify the presence of a gas molecule in\nmetallic atomic contacts.",
        "positive": "Comment on two recent arXiv postings [arXiv:1412.2200 and\n  arXiv:1412.8244]: This is a comment on two recent arXiv postings."
    },
    {
        "anchor": "Exciton-polariton condensation in a natural two dimensional trap: Bose Einstein condensation of exciton-polaritons has recently been reported\nin homogeneous structures only affected by random in-plane fluctuations. We\nhave taken advantage of the ubiquitous defects in semiconductor microcavities\nto reveal the spontaneous dynamical condensation of polaritons in the quantised\nlevels of a trap. We observe condensation in several quantized states, taking\ntheir snapshots in real and reciprocal space. We show also the effect of\nparticle interactions for high occupations numbers, revealed by a change in the\nconfined wave function toward the Thomas Fermi profile.",
        "positive": "Weak localization of the open kicked rotator: We present a numerical calculation of the weak localization peak in the\nmagnetoconductance for a stroboscopic model of a chaotic quantum dot. The\nmagnitude of the peak is close to the universal prediction of random-matrix\ntheory. The width depends on the classical dynamics, but this dependence can be\naccounted for by a single parameter: the level curvature around zero magnetic\nfield of the closed system."
    },
    {
        "anchor": "Evidence of the Coulomb gap in the density of states of MoS$_2$: $\\mathrm{MoS_2}$ is an emergent van der Waals material that shows promising\nprospects in semiconductor industry and optoelectronic applications. However,\nits electronic properties are not yet fully understood. In particular, the\nnature of the insulating state at low carrier density deserves further\ninvestigation, as it is important for fundamental research and applications. In\nthis study, we investigate the insulating state of a dual-gated exfoliated\nbilayer $\\mathrm{MoS_2}$ field-effect transistor by performing magnetotransport\nexperiments. We observe positive and non-saturating magnetoresistance, in a\nregime where only one band contributes to electron transport. At low electron\ndensity ($\\sim 1.4\\times 10^{12}~\\mathrm{cm^{-2}}$) and a perpendicular\nmagnetic field of 7 Tesla, the resistance exceeds by more than one order of\nmagnitude the zero field resistance and exponentially drops with increasing\ntemperature. We attribute this observation to strong electron localization.\nBoth temperature and magnetic field dependence can, at least qualitatively, be\ndescribed by the Efros-Shklovskii law, predicting the formation of a Coulomb\ngap in the density of states due to Coulomb interactions. However, the\nlocalization length obtained from fitting the temperature dependence exceeds by\nmore than one order of magnitude the one obtained from the magnetic field\ndependence. We attribute this discrepancy to the presence of a nearby metallic\ngate, which provides electrostatic screening and thus reduces long-range\nCoulomb interactions. The result of our study suggests that the insulating\nstate of $\\mathrm{MoS_2}$ originates from a combination of disorder-driven\nelectron localization and Coulomb interactions.",
        "positive": "Influence of Joule heating on current-induced domain wall depinning: The domain wall depinning from a notch in a Permalloy nanostrip on top of a\n${\\rm SiO_2/Si}$ substrate is studied theoretically under application of static\nmagnetic fields and the injection of short current pulses. The influence of\nJoule heating on current-induced domain wall depinning is explored\nself-consistently by coupling the magnetization dynamics in the ferromagnetic\nstrip to the heat transport throughout the system. Our results indicate that\nJoule heating plays a remarkable role in these processes, resulting in a\nreduction in the critical depinning field and/or in a temporary destruction of\nthe ferromagnetic order for typically injected current pulses. In agreement\nwith experimental observations, similar pinning-depinning phase diagrams can be\ndeduced for both current polarities when the Joule heating is taken into\naccount. These observations, which are incompatible with the sole contribution\nof spin transfer torques, provide a deeper understanding of the physics\nunderlying these processes and establish the real scope of the spin transfer\ntorque. They are also relevant for technological applications based on\ncurrent-induced domain-wall motion along soft strips."
    },
    {
        "anchor": "Electronic and Transport Properties of Molecular Junctions under a\n  Finite Bias: A Dual Mean Field Approach: We show that when a molecular junction is under an external bias, its\nproperties can not be uniquely determined by the total electron density in the\nsame manner as the density functional theory (DFT) for ground state (GS)\nproperties. In order to correctly incorporate bias-induced nonequilibrium\neffects, we present a dual mean field (DMF) approach. The key idea is that the\ntotal electron density together with the density of current-carrying electrons\nare sufficient to determine the properties of the system. Two mean fields, one\nfor current-carrying electrons and the other one for equilibrium electrons can\nthen be derived.By generalizing the Thomas-Fermi-Dirac (TFD) model to\nnon-equilibrium cases, we analytically derived the DMF exchange energy density\nfunctional. We implemented the DMF approach into the computational package\nSIESTA to study non-equilibrium electron transport through molecular junctions.\nCalculations for a graphene nanoribbon (GNR) junction show that compared with\nthe commonly used \\textit{ab initio} transport theory, the DMF approach could\nsignificantly reduce the electric current at low biases due to the\nnon-equilibrium corrections to the mean field potential in the scattering\nregion.",
        "positive": "Spin degree of freedom in two dimensional exciton condensates: We present a theoretical analysis of a spin-dependent multicomponent\ncondensate in two dimensions. The case of a condensate of resonantly\nphotoexcited excitons having two different spin orientations is studied in\ndetail. The energy and the chemical potentials of this system depend strongly\non the spin polarization . When electrons and holes are located in two\ndifferent planes, the condensate can be either totally spin polarized or spin\nunpolarized, a property that is measurable. The phase diagram in terms of the\ntotal density and electron-hole separation is discussed."
    },
    {
        "anchor": "0.7-anomaly and magnetotransport of disordered quantum wires: The unexpected \"0.7\" plateau of conductance quantisation is usually observed\nfor ballistic one-dimensional devices. In this work we study a quasi-ballistic\nquantum wire, for which the disorder induced backscattering reduces the\nconductance quantisation steps. We find that the transmission probability\nresonances coexist with the anomalous plateau. The studies of these resonances\nas a function of the in-plane magnetic field and electron density point to the\npresence of spin polarisation at low carrier concentrations and constitute a\nmethod for the determination of the effective g-factor suitable for disordered\nquantum wires.",
        "positive": "On the interpretation of wave function overlaps in quantum dots: The spontaneous emission rate of excitons strongly confined in quantum dots\nis proportional to the overlap integral of electron and hole envelope wave\nfunctions. A common and intuitive interpretation of this result is that the\nspontaneous emission rate is proportional to the probability that the electron\nand the hole are located at the same point or region in space, i.e. they must\ncoincide spatially to recombine. Here we show that this interpretation is not\ncorrect even loosely speaking. By general mathematical considerations we\ncompare the envelope wave function overlap, the exchange overlap integral, and\nthe probability of electrons and holes coinciding and find that the frequency\ndependence of the envelope wave function overlap integral is very different\nfrom that expected from the common interpretation. We show that these\ntheoretical considerations lead to predictions for measurements. We compare our\nqualitative predictions with recent measurements of the wave function overlap\nand find good agreement."
    },
    {
        "anchor": "Effects of n-type doping in InAs/GaAs quantum dot layer on\n  current-voltage characteristic of intermediate band solar cells: We investigated the current-voltage characteristic of InAs/GaAs quantum dot\nintermediate band solar cells (QD IBSCs) with different n-type doping density\nin the QD layer. The n-type doping evidently increases the open circuit\nvoltage, meanwhile decreases the short circuit current density, and leads to\nthe conversion efficiency approaching that of the control solar cell, that is\nthe major role of n-type doping is to suppress the effects of QDs on the\ncurrent-voltage characteristic. Our model adopts practical parameters for\nsimulation rather than those from detailed balanced method, so that the results\nin our simulation are not overestimated.",
        "positive": "S-duality constraints on 1D patterns associated with fractional quantum\n  Hall states: Using the modular invariance of the torus, constraints on the 1D patterns are\nderived that are associated with various fractional quantum Hall ground states,\ne.g. through the thin torus limit. In the simplest case, these constraints\nenforce the well known odd-denominator rule, which is seen to be a necessary\nproperty of all 1D patterns associated to quantum Hall states with minimum\ntorus degeneracy. However, the same constraints also have implications for the\nnon-Abelian states possible within this framework. In simple cases, including\nthe $\\nu=1$ Moore-Read state and the $\\nu=3/2$ level 3 Read-Rezayi state, the\nfilling factor and the torus degeneracy uniquely specify the possible patterns,\nand thus all physical properties that are encoded in them. It is also shown\nthat some states, such as the \"strong p-wave pairing state\", cannot in\nprinciple be described through patterns."
    },
    {
        "anchor": "Tunable valley Hall effect in gate-defined graphene superlattices: We theoretically investigate gate-defined graphene superlattices with broken\ninversion symmetry as a platform for realizing tunable valley dependent\ntransport. Our analysis is motivated by recent experiments [C. Forsythe et al.,\nNat. Nanotechnol. 13, 566 (2018)] wherein gate-tunable superlattice potentials\nhave been induced on graphene by nanostructuring a dielectric in the\ngraphene/patterneddielectric/gate structure. We demonstrate how the electronic\ntight-binding structure of the superlattice system resembles a gapped Dirac\nmodel with associated valley dependent transport using an unfolding procedure.\nIn this manner we obtain the valley Hall conductivities from the Berry\ncurvature distribution in the superlattice Brillouin zone, and demonstrate the\ntunability of this conductivity by the superlattice potential. Finally, we\ncalculate the valley Hall angle relating the transverse valley current and\nlongitudinal charge current and demonstrate the robustness of the valley\ncurrents against irregularities in the patterned dielectric.",
        "positive": "Hamiltonian theory of the half-filled Landau level with disorder:\n  Application to recent NMR data: The Hamiltonian Theory of the fractional quantum Hall effect is an operator\ndescription that subsumes many properties of Composite Fermions, applies to\ngapped and gapless cases, and has been found to provide results in quantitative\naccord with data on gaps, relaxation rates and polarizations at temperatures of\n$300mK$ and above. The only free parameter is $\\lambda$, which is related to\nthe sample thickness and appears in the Zhang-Das Sarma potential $v(q) = {2\\pi\ne^2\\over \\kappa q} e^{-ql\\lambda}$ where $l$ and $\\kappa $ are the magnetic\nlength and dielectric constant. Here we examine the recent data of Tracy and\nEisenstein on the nuclear magnetic resonance relaxation rate at filling factor\n$\\nu=\\half$ deduced from resistivity measurements at temperatures as low as\n$45mK$. We find that their results can be satisfactorily described by this\ntheory, if in addition to a $v(q)$ with $\\lambda \\simeq 2$, a constant disorder\nwidth $\\Gamma\\simeq 100 mK$ is incorporated."
    },
    {
        "anchor": "Goos-Hanchen Shift of a Spin-Wave Beam at the Interface Between Two\n  Ferromagnets: Spin waves are promising information carriers which can be used in modern\nmagnonic devices, characterized by higher performance and lower energy\nconsumption than presently used electronic circuits. However, before practical\napplication of spin waves, the efficient control over spin wave amplitude and\nphase needs to be developed. We analyze analytically reflection and refraction\nof the spin waves at the interface between two ferromagnetic materials. In the\nmodel we consider the system consisting of two semi-infinite ferromagnetic\nmedia, separated by the ultra-narrow interface region with the magnetic\nanisotropy. We have found the Goos-Hanchen shift for spin waves in transmission\nand reflection, and performed detailed investigations of its dependence on the\nanisotropy at the interface and materials surrounding the interface. We have\ndemonstrated possibility of obtaining Goos-Hanchen shift of several wavelengths\nin reflection for realistic material parameters. That proves the possibility\nfor change of the spin waves phase in ferromagnetic materials at subwavelength\ndistances, which can be regarded as a metasurface for magnonics.",
        "positive": "Tailoring population inversion in Landau-Zener-St\u00fcckelberg\n  interferometry of flux qubits: We distinguish different mechanisms for population inversion in flux qubits\ndriven by dc+ac magnetic fields. We show that for driving amplitudes such that\nthere are Landau-Zener-St\\\"uckelberg intereferences, it is possible to have\npopulation inversion solely mediated by the environmental bath at long driving\ntimes. We study the effect of the resonant frequency $\\Omega_p$ of the\nmeasuring circuit, finding different regimes for the asymptotic population of\nthe state of the flux qubit. By tailoring $\\Omega_p$ the degree of population\ninversion can be controlled. Our studies are based on realistic simulations of\nthe device for the Josephson flux qubit using the Floquet-Born-Markov\nformalism."
    },
    {
        "anchor": "Fabrication of graphene nanoribbon by local anodic oxidation lithography\n  using atomic force microscope: We conducted local anodic oxidation (LAO) lithography in single-layer,\nbilayer, and multilayer graphene using tapping-mode atomic force microscope.\nThe width of insulating oxidized area depends systematically on the number of\ngraphene layers. An 800-nm-wide bar-shaped device fabricated in single-layer\ngraphene exhibits the half-integer quantum Hall effect. We also fabricated a\n55-nm-wide graphene nanoribbon (GNR). The conductance of the GNR at the charge\nneutrality point was suppressed at low temperature, which suggests the opening\nof an energy gap due to lateral confinement of charge carriers. These results\nshow that LAO lithography is an effective technique for the fabrication of\ngraphene nanodevices.",
        "positive": "Experimental Realization of the 1D Random Field Ising Model: We have measured magnetic-field-induced avalanches in a square artificial\nspin ice array of interacting nanomagnets. Starting from the ground state\nordered configuration, we imaged the individual nanomagnet moments after each\nsuccessive application of an incrementally increasing field. The statistics of\nthe evolution of the moment configuration show good agreement with the\ncanonical one-dimensional random field Ising model. We extract information\nabout the microscopic structure of the arrays from our macroscopic measurements\nof their collective behavior, demonstrating a process that could be applied to\nother systems exhibiting avalanches."
    },
    {
        "anchor": "Spin polarization amplification within nonmagnetic semiconductors at\n  room temperature: We demonstrate theoretically that the spin polarization of current can be\nelectrically amplified within nonmagnetic semiconductors by exploiting the fact\nthe spin current, compared to the charge current, is weakly perturbed by\nelectric driving forces. As a specific example, we consider a T-shaped current\nbranching geometry made entirely of a nonmagnetic semiconductor, where the\ncurrent is injected into one of the branches (input branch) and splits into the\nother two branches (output branches). We show that when the input current has a\nmoderate spin polarization, the spin polarization in one of the output branches\ncan be higher than the spin polarization in the input branch and may reach 100%\nwhen the relative magnitudes of current-driving electric fields in the two\noutput branches are properly tuned. The proposed amplification scheme does not\nuse ferromagnets or magnetic fields, and does not require low temperature\noperation, providing an efficient way to generate a highly spin polarized\ncurrent in nonmagnetic semiconductors at room temperature.",
        "positive": "Nontrivial Berry phase and type II Dirac transport in layered material\n  PdTe2: Here we report the evidence of the type II Dirac Fermion in the layered\ncrystal PdTe2. The de Haas-van Alphen oscillations find a small Fermi pocket\nwith a cross section of 0.077nm-2 with a nontrivial Berry phase.\nFirst-principal calculations reveal that it is originated from the hole pocket\nof a tilted Dirac cone. Angle Resolved Photoemission Spectroscopy demonstrates\na type II Dirac cone featured dispersion. We also suggest PdTe2 is an improved\nplatform to host the topological superconductors."
    },
    {
        "anchor": "Atomic structure of Mn wires on Si(001) resolved by scanning tunneling\n  microscopy: At submonolayer coverage, Mn forms atomic wires on the Si(001) surface\noriented perpendicular to the underlying Si dimer rows. While many other\nelements form symmetric dimer wires at room temperature, we show that Mn wires\nhave an asymmetric appearance and pin the Si dimers nearby. We find that an\natomic configuration with a Mn trimer unit cell can explain these observations\ndue to the interplay between the Si dimer buckling phase near the wire and the\norientation of the Mn trimer. We study the resulting four wire configurations\nin detail using high-resolution scanning tunneling microscopy (STM) imaging and\ncompare our findings with STM images simulated by density functional theory.",
        "positive": "Faraday effect in bi-periodic photonic-magnonic crystals: We present a theoretical investigation of the polarization plane rotation at\nlight transmission - Faraday effect, through one-dimensional multilayered\nmagneto-photonic systems consisting of periodically distributed magnetic and\ndielectric layers. We calculate Faraday rotation spectra of photonic-magnonic\ncrystals, where cell (or supercell) is composed of magnetic layer and\ndielectric layer (or section of dielectric photonic crystal). We found that the\nFaraday rotation of p-polarized incident light is increasing in the\ntransmission band with the number of magnetic supercells. The increase of\nFaraday rotation is observed also in vicinity of the band-gap modes localized\nin magnetic layers but the maximal polarization plane rotation angles are\nreached at minimal transmittivity. We show that presence of linear\nmagneto-electric interaction in the magnetic layers leads to significant\nincrease of the Faraday rotation angles of s-polarized incident light in the\nvicinity of the fine-structured modes inside the photonic-band-gap."
    },
    {
        "anchor": "Spin-dependent tunneling in the nearly-free-electron model: Spin-dependent ballistic transport through a tunnel barrier is treated within\nthe one-dimensional nearly-free-electron model. The comparison with free\nelectrons reveals significant effects of band gaps, in particular in the bias\ndependence. The results are qualitatively explained by the number of incident\nand transmitted states in the leads. With an extension to ferromagnetic leads\nthe bias dependence of tunnel magneto-resistance is discussed.",
        "positive": "Tuning of structure inversion asymmetry by the $\u03b4$-doping position\n  in (001)-grown GaAs quantum wells: Structure and bulk inversion asymmetry in doped (001)-grown GaAs quantum\nwells is investigated by applying the magnetic field induced photogalvanic\neffect. We demonstrate that the structure inversion asymmetry (SIA) can be\ntailored by variation of the delta-doping layer position. Symmetrically-doped\nstructures exhibit a substantial SIA due to impurity segregation during the\ngrowth process. Tuning the SIA by the delta-doping position we grow samples\nwith almost equal degrees of structure and bulk inversion asymmetry."
    },
    {
        "anchor": "Generalized Bloch theorem and topological characterization: The Bloch theorem enables reduction of the eigenvalue problem of the\nsingle-particle Hamiltonian that commutes with translational group. Based on a\ngroup theory analysis we present generalization of the Bloch theorem that\nincorporates all additional symmetries of a crystal. The generalized Bloch\ntheorem constrains the form of the Hamiltonian which becomes manifestly\ninvariant under additional symmetries. In the case of isotropic interactions\nthe generalized Bloch theorem gives a unique Hamiltonian. This Hamiltonian\ncoincides with the Hamiltonian in the periodic gauge. In the case of\nanisotropic interactions the generalized Bloch theorem allows a family of\nHamiltonians. Due to the continuity argument we expect that even in this case\nthe Hamiltonian in the periodic gauge defines observables, such as Berry\ncurvature, in the inverse space. For both cases we present examples and\ndemonstrate that the average of the Berry curvatures of all possible\nHamiltonians in the Bloch gauge is the Berry curvature in the periodic gauge.",
        "positive": "Molecularly Resolved Electronic Landscapes of Differing Acceptor-Donor\n  Interface Geometries: Organic semiconductors are a promising class of materials for numerous\nelectronic and optoelectronic applications, including solar cells. However,\nthese materials tend to be extremely sensitive to the local environment and\nsurrounding molecular geometry, causing the energy levels near boundaries and\ninterfaces essential to device function to differ from those of the bulk.\nScanning Tunneling Microscopy and Spectroscopy (STM/STS) has the ability to\nexamine both the structural and electronic properties of these interfaces on\nthe molecular and submolecular scale. Here we investigate the prototypical\nacceptor/donor system PTCDA/CuPc using sub-molecularly resolved pixel-by-pixel\nSTS to demonstrate the importance of subtle changes in interface geometry in\nprototypical solar cell materials. PTCDA and CuPc were sequentially deposited\non NaCl bilayers to create lateral heterojunctions that were decoupled from the\nunderlying substrate. Donor and acceptor states were observed to shift in\nopposite directions suggesting an equilibrium charge transfer between the two.\nNarrowing of the gap energy compared to isolated molecules on the same surface\nare indicative of the influence of the local dielectric environment. Further,\nwe find that the electronic state energies of both acceptor and donor are\nstrongly dependent on the ratio and positioning of both molecules in larger\nclusters. This molecular-scale structural dependence of the electronic states\nof both interfacial acceptor and donor has significant implications for device\ndesign where level alignment strongly correlates to device performance."
    },
    {
        "anchor": "Tracking Quasiparticle Energies in Graphene with Near Field Optics: Advances in infrared nanoscopy have enabled access to the finite momentum\noptical conductivity $\\sigma(\\vec{q},\\omega)$. The finite momentum optical\nconductivity in graphene has a peak at the Dirac fermion quasiparticle energy\n$\\epsilon(k_F-q)$, i.e. at the Fermi momentum minus the incident photon\nmomentum. We find that the peak remains robust even at finite temperature as\nwell as with residual scattering. It can be used to trace out the fermion\ndispersion curves. However, this effect depends strongly on the linearity of\nthe Dirac dispersion. Should the Dirac fermions acquire a mass, the peak in\n$\\sigma(q,w)$ shifts to lower energies and broadens as optical spectral weight\nis redistributed over an energy range of the order of the mass gap energy. Even\nin this case structures remain in the conductivity which can be used to\ndescribe the excitation spectrum. By contrast, in graphene strained along the\narmchair direction, the peak remains intact, but shifts to a lower value of $q$\ndetermined by the anisotropy induced by the deformation.",
        "positive": "Renormalization of competing interactions and superconductivity on small\n  scales: The interaction-induced orbital magnetic response of a nanoscale ring is\nevaluated for a diffusive system which is a superconductor in the bulk. The\ninterplay of the renormalized Coulomb and Fr\\\"{o}hlich interactions is crucial.\nThe magnetic susceptibility which results from the fluctuations of the uniform\nsuperconducting order parameter is diamagnetic (paramagnetic) when the\nrenormalized combined interaction is attractive (repulsive). Above the\ntransition temperature of the bulk the total magnetic susceptibility has\ncontributions from many wave-vector- and (Matsubara) frequency-dependent order\nparameter fluctuations. Each of these contributions results from a different\nrenormalization of the relevant coupling energy, when one integrates out the\nfermionic degrees of freedom. The total diamagnetic response of the large\nsuperconductor may become paramagnetic when the system's size decreases."
    },
    {
        "anchor": "Nonlinear electromagnetic response for Hall effect in time-reversal\n  breaking materials: It is known that materials with broken time-reversal symmetry can have Hall\nresponses. Here we show that in addition to the conventional currents, either\nlinear or nonlinear in the electric field, another Hall current can occur in\nthe time-reversal breaking materials within the second-order response to\nin-plane electric and vertical magnetic fields. Such a Hall response is\ngenerated by the oscillation of the electromagnetic field and has a quantum\norigin arising from a novel dipole associated with the Berry curvature and band\nvelocity. We demonstrate that the massive Dirac model of LaAlO3/LaNiO3/LaAlO3\nquantum well can be used to detect this Hall effect. Our work widens the theory\nof the Hall effect in the time-reversal breaking materials by proposing a new\nkind of nonlinear electromagnetic response.",
        "positive": "Chaotic dynamics in a macrospin spin-torque nano-oscillator with delayed\n  feedback: A theoretical study of delayed feedback in spin-torque nano-oscillators is\npresented. A macrospin geometry is considered, where self-sustained\noscillations are made possible by spin transfer torques associated with spin\ncurrents flowing perpendicular to the film plane. By tuning the delay and\namplification of the self-injected signal, we identify dynamical regimes in\nthis system such as chaos, switching between precession modes with complex\ntransients, and oscillator death. Such delayed feedback schemes open up a new\nfield of exploration for such oscillators, where the complex transient states\nmight find important applications in information processing."
    },
    {
        "anchor": "Topological Phases in InAs$_{1-x}$Sb$_x$: From Novel Topological\n  Semimetal to Majorana Wire: Superconductor proximitized one-dimensional semiconductor nanowires with\nstrong spin-orbit interaction (SOI) are at this time the most promising\ncandidates for the realization of topological quantum information processing.\nIn current experiments the SOI originates predominantly from extrinsic fields,\ninduced by finite size effects and applied gate voltages. The dependence of the\ntopological transition in these devices on microscopic details makes scaling to\na large number of devices difficult unless a material with dominant intrinsic\nbulk SOI is used. Here we show that wires made of certain ordered alloys\nInAs$_{1-x}$Sb$_x$ have spin-splittings up to 20 times larger than those\nreached in pristine InSb wires. In particular, we show this for a stable\nordered CuPt-structure at $x = 0.5$, which has an inverted band ordering and\nrealizes a novel type of a topological semimetal with triple degeneracy points\nin the bulk spectrum that produce topological surface Fermi arcs.\nExperimentally achievable strains can drive this compound either into a\ntopological insulator phase, or restore the normal band ordering making the\nCuPt-ordered InAs$_{0.5}$Sb$_{0.5}$ a semiconductor with a large intrinsic\nlinear in $k$ bulk spin splitting.",
        "positive": "All electrically controlled quantum gates for single heavy hole spin\n  qubits: In this paper, several nanodevices which realize basic single heavy hole\nqubit operations are proposed and supported by time dependent self consistent\nPoisson-Schr\\\"{o}dinger calculations using a four band heavy hole-light hole\nmodel. In particular we propose a set of nanodevices which can act as Pauli X,\nY, Z quantum gates and as a gate that acts similar as a Hadamard gate (i.e. it\ncreates a balanced superposition of basis states but with an additional phase\nfactor) on the heavy hole spin qubit. We also present the design and simulation\nof a gated semiconductor nanodevice which can realize an arbitrary sequence of\nall these proposed single quantum logic gates. The proposed devices exploit the\nself-focusing effect of the hole wave function which allows for guiding the\nhole along a given path in the form of a stable soliton-like wave packet.\nThanks to the presence of the Dresselhaus spin orbit coupling, the motion of\nthe hole along a certain direction is equivalent to the application of an\neffective magnetic field which induces in turn a coherent rotation of the heavy\nhole spin. The hole motion and consequently the quantum logic operation is\ninitialized only by weak static voltages applied to the electrodes which cover\nthe nanodevice. The proposed gates allow for an all electric and ultrafast\n(tens of picoseconds) heavy hole spin manipulation and give the possibility to\nimplement a scalable architecture of heavy hole spin qubits for quantum\ncomputation applications."
    },
    {
        "anchor": "Model and Simulations of the Epitaxial Growth of Graphene on Non-Planar\n  6H-SiC Surfaces: We study step flow growth of epitaxial graphene on 6H-SiC using a one\ndimensional kinetic Monte Carlo model. The model parameters are effective\nenergy barriers for the nucleation and propagation of graphene at the SiC\nsteps. When the model is applied to graphene growth on vicinal surfaces, a\nstrip width distribution is used to characterize the surface morphology.\nAdditional kinetic processes are included to study graphene growth on SiC\nnano-facets. Our main result is that the original nano-facet is fractured into\nseveral nano-facets during graphene growth. This phenomenon is characterized by\nthe angle at which the fractured nano-facet is oriented with respect to the\nbasal plane. The distribution of this angle across the surface is found to be\nrelated to the strip width distribution for vicinal surfaces. As the terrace\npropagation barrier decreases, the fracture angle distribution changes\ncontinously from two-sided Gaussian to one-sided power-law. Using this\ndistribution, it will be possible to extract energy barriers from experiments\nand interpret the growth morphology quantitatively.",
        "positive": "Large dynamical axion field in topological antiferromagnetic insulator\n  Mn$_2$Bi$_2$Te$_5$: The dynamical axion field is a new state of quantum matter where the\nmagnetoelectric response couples strongly to its low-energy magnetic\nfluctuations. It is fundamentally different from an axion insulator with a\nstatic quantized magnetoelectric response. The dynamical axion field exhibits\nmany exotic phenomena such as axionic polariton and axion instability. However,\nthese effects have not been experimentally confirmed due to the lack of proper\ntopological magnetic materials. Here by combining analytic models and\nfirst-principles calculations, we predict a series of van der Waal layered\nMn$_2$Bi$_2$Te$_5$-related topological antiferromagnetic materials could host\nthe long-sought dynamical axion field with a topological origin. We also show a\nlarge dynamical axion field can be achieved in antiferromagnetic insulating\nstates close to the topological phase transition. We further propose the\noptical and transport experiments to detect such a dynamical axion field. Our\nresults could directly aid and facilitate the search for topological-origin\nlarge dynamical axion field in realistic materials."
    },
    {
        "anchor": "Quantum Computers and Quantum Coherence: If the states of spins in solids can be created, manipulated, and measured at\nthe single-quantum level, an entirely new form of information processing,\nquantum computing, will be possible. We first give an overview of quantum\ninformation processing, showing that the famous Shor speedup of integer\nfactoring is just one of a host of important applications for qubits, including\ncryptography, counterfeit protection, channel capacity enhancement, distributed\ncomputing, and others. We review our proposed spin-quantum dot architecture for\na quantum computer, and we indicate a variety of first generation materials,\noptical, and electrical measurements which should be considered. We analyze the\nefficiency of a two-dot device as a transmitter of quantum information via the\nballistic propagation of carriers in a Fermi sea.",
        "positive": "Crystal mean field based trial wavefunctions for the FQHE ground states: Employing the Haldane-Rezayi periodic representation, the crystalline\ndeterminantal Hall crystal mean field solutions derived in previous works are\nused to construct variational wavefunctions for the FQHE at $\\nu=1/q$. The\nproposed states optimize the short range correlations in a similar measure as\nthe Laughlin ones, since the zero of the states when the coordinates of two\nparticles join is of order $q$. However, the proposed wavefunctions also\nincorporate the crystalline correlations of the mean field problem, through a\ndeterminantal mean field function entering their construction. The above\nproperties, lead to the expectation that the considered states can be\ncompetitive in energy per particle with the Laughlin ones. Their similar\nstructure also could explain way the breaking of the translation invariance in\nthe FQHE ground states can result to be a weak one, which after disregarded,\nproduce the Laughlin states as good approximations. Calculation for checking\nthese possibilities are under consideration."
    },
    {
        "anchor": "Photoconductance of a submicron oxidized line in surface conductive\n  single crystalline diamond: We report on sub-bandgap optoelectronic phenomena of hydrogen-terminated\ndiamond patterned with a submicron oxidized line. The line acts as an energy\nbarrier for the two-dimensional hole gas located below the hydrogenated diamond\nsurface. A photoconductive gain of the hole conductivity across the barrier is\nmeasured for sub-bandgap illumination. The findings are consistent with\nphotogenerated electrons being trapped in defect levels within the barrier. We\ndiscuss the spatial and energetic characteristics of the optoelectronic\nphenomena, as well as possible photocurrent effects.",
        "positive": "Bistability in the Tunnelling Current through a Ring of $N$ Coupled\n  Quantum Dots: We study bistability in the electron transport through a ring of N coupled\nquantum dots with two orbitals in each dot. One orbital is localized (called b\norbital) and coupling of the b orbitals in any two dots is negligible; the\nother is delocalized in the plane of the ring (called d orbital), due to\ncoupling of the d orbitals in the neighboring dots, as described by a\ntight-binding model. The d orbitals thereby form a band with finite width. The\nb and d orbitals are connected to the source and drain electrodes with a\nvoltage bias V, allowing the electron tunnelling. Tunnelling current is\ncalculated by using a nonequilibrium Green function method recently developed\nto treat nanostructures with multiple energy levels. We find a bistable effect\nin the tunnelling current as a function of bias V, when the size N>50; this\neffect scales with the size N and becomes sizable at N~100. The temperature\neffect on bistability is also discussed. In comparison, mean-field treatment\ntends to overestimate the bistable effect."
    },
    {
        "anchor": "Magnon transport and spin current switching through quantum dots: We study the nonequilibrium spin current through a quantum dot consisting of\ntwo localized spin-1/2 coupled to two ferromagnetic insulators. The influence\nof an intra-dot magnetic field and exchange coupling, different dot-reservoir\ncoupling configurations, and the influence of magnon chemical potential\ndifferences vs. magnetic field gradients onto the spin current are examined. We\ndiscuss various spin switching mechanisms and find that, in contrast to\nelectronic transport, the spin current is very sensitive to the specific\ncoupling configuration and band edges. In particular, we identify 1- and\n2-magnon transport processes which can lead to resonances and antiresonances\nfor the spin current.",
        "positive": "Nanoscale magnetism and magnetic phase transitions in atomically thin\n  CrSBr: Since their first observation in 2017, atomically thin van der Waals (vdW)\nmagnets have attracted significant fundamental, and application-driven\nattention. However, their low ordering temperatures, $T_c$, sensitivity to\natmospheric conditions and difficulties in preparing clean large-area samples\nstill present major limitations to further progress. The remarkably stable\nhigh-$T_c$ vdW magnet CrSBr has the potential to overcome these key\nshortcomings, but its nanoscale properties and rich magnetic phase diagram\nremain poorly understood. Here we use single spin magnetometry to\nquantitatively characterise saturation magnetization, magnetic anisotropy\nconstants, and magnetic phase transitions in few-layer CrSBr by direct magnetic\nimaging. We show pristine magnetic phases, devoid of defects on micron\nlength-scales, and demonstrate remarkable air-stability down the monolayer\nlimit. We address the spin-flip transition in bilayer CrSBr by direct imaging\nof the emerging antiferromagnetic (AFM) to ferromagnetic (FM) phase wall and\nelucidate the magnetic properties of CrSBr around its ordering temperature. Our\nwork will enable the engineering of exotic electronic and magnetic phases in\nCrSBr and the realisation of novel nanomagnetic devices based on this highly\npromising vdW magnet."
    },
    {
        "anchor": "Hetero-structure Mode Space Method for Efficient Device Simulations: The Hamiltonian size reduction method or the mode space method applicable to\ngeneral heterogeneous structures is developed in this work. The effectiveness\nand accuracy of the method are demonstrated for four example devices of\nGaSb/InAs tunnel field effect transistor (FET), MoTe2/SnS2 bilayer vertical\nFET, InAs nanowire FET with a defect, and Si nanowire FET with rough surfaces.\nThe Hamiltonian size is reduced to around 5 % of the original full Hamiltonian\nsize without losing the accuracy of the calculated transmission and local\ndensity of states in a practical sense. The method developed in this work can\nbe used with any type of Hamiltonian and can be applied to virtually any\nhetero-structure, so it has the potential to become an enabling technology for\nefficient simulations of hetero-structures.",
        "positive": "Heat Transfer Through Near-Field Interactions in Nanofluids: Using the Landauer-Buttiker theory we calculate the thermal conductance\nassociated to plasmons modes in one dimensional arrays of nanoparticles closely\nspaced in a host fluid. Our numerical simulations show that the near-field\ninteractions between particles have a negligible effect on the thermal\nconductivity of nanoparticles colloidal solutions (nanofluids)."
    },
    {
        "anchor": "Weak localization in GaMnAs: evidence of impurity band transport: We report the observation of negative magnetoresistance in the ferromagnetic\nsemiconductor GaMnAs at low temperatures ($T<3$ K) and low magnetic fields ($0<\nB <20$ mT). We attribute this effect to weak localization. Observation of weak\nlocalization provides a strong evidence of impurity band transport in these\nmaterials, since for valence band transport one expects either weak\nanti-localization due to strong spin-orbit interactions or total suppression of\ninterference by intrinsic magnetization. In addition to the weak localization,\nwe observe Altshuler-Aronov electron-electron interactions effect in this\nmaterial.",
        "positive": "Tunable non-additivity in Casimir-Lifshitz force between graphene\n  gratings: We investigate the Casimir-Lifshitz force (CLF) between two identical\ngraphene strip gratings, laid on finite dielectric substrates, by using the\nscattering matrix (S-matrix) approach derived from the Fourier Modal Method\nwith Local Basis Functions (FMM-LBF). We fully take into account the high-order\nelectromagnetic diffractions, the multiple scattering and the exact 2D feature\nof the graphene strips. We show that the non-additivity, which is one of the\nmost interesting features of the CLF in general, is significantly high and can\nbe modulated in situ, without any change in the actual material geometry and\nthis by varying the graphene chemical potential. We discuss the nature of the\ngeometrical effects and show the relevance of the geometric parameter d/D (i.e.\nthe ratio between separation and grating period), which allows to explore the\nregions of parameters where the additive result is fully acceptable or where\nthe full calculation is needed. This study can open to deeper experimental\nexploration of the non-additive features of the CLF with micro- or\nnano-electromechanical graphene-based systems."
    },
    {
        "anchor": "Spin-directed network model for the surface states of weak\n  three-dimensional $\\mathbb{Z}^{\\,}_{2}$ topological insulators: A two-dimensional spin-directed $\\mathbb{Z}^{\\,}_{2}$ network model is\nconstructed that describes the combined effects of dimerization and disorder\nfor the surface states of a weak three-dimensional $\\mathbb{Z}^{\\,}_{2}$\ntopological insulator. The network model consists of helical edge states of\ntwo-dimensional layers of $\\mathbb{Z}^{\\,}_{2}$ topological insulators which\nare coupled by time-reversal symmetric interlayer tunneling. It is argued that,\nwithout dimerization of interlayer couplings, the network model has no\ninsulating phase for any disorder strength. However, a sufficiently strong\ndimerization induces a transition from a metallic phase to an insulating phase.\nThe critical exponent $\\nu$ for the diverging localization length at\nmetal-insulator transition points is obtained by finite-size scaling analysis\nof numerical data from simulations of this network model. It is shown that the\nphase transition belongs to the two-dimensional symplectic universality class\nof Anderson transition.",
        "positive": "Giant magnetoresistance in the junction of two ferromagnets on the\n  surface of diffusive topological insulators: We reveal the giant magnetoresistance induced by the spin-polarized current\nin the ferromagnet (F_1)/topological insulator (TI)/ferromagnet (F_2) junction,\nwhere two ferromagnets are deposited on the diffusive surface of the TI. We can\nincrease and reduce the value of the giant magnetoresistance by tuning the\nspin-polarized current, which is controlled by the magnetization\nconfigurations. The property is intuitively understood by the non-equilibrium\nspin-polarized current, which plays the role of an effective electrochemical\npotential on the surface of the TI."
    },
    {
        "anchor": "The effects of non-abelian statistics on two-terminal shot noise in a\n  quantum Hall liquid in the Pfaffian state: We study non-equilibrium noise in the tunnelling current between the edges of\na quantum Hall liquid in the Pfaffian state, which is a strong candidate for\nthe plateau at $\\nu=5/2$. To first non-vanishing order in perturbation theory\n(in the tunneling amplitude) we find that one can extract the value of the\nfractional charge of the tunnelling quasiparticles. We note however that no\ndirect information about non-abelian statistics can be retrieved at this level.\nIf we go to higher-order in the perturbative calculation of the non-equilibrium\nshot noise, we find effects due to non-Abelian statistics. They are subtle, but\neventually may have an experimental signature on the frequency dependent shot\nnoise. We suggest how multi-terminal noise measurements might yield a more\ndramatic signature of non-Abelian statistics and develop some of the relevant\nformalism.",
        "positive": "Conduction mechanisms in biphenyl-dithiol single-molecule junctions: Based on density-functional theory calculations, we report a detailed study\nof the single-molecule charge-transport properties for a series of recently\nsynthesized biphenyl-dithiol molecules [D. Vonlanthen et al., Angew. Chem.,\nInt. Ed. 48, 8886 (2009); A. Mishchenko et al., Nano Lett. 10, 156 (2010)]. The\ntorsion angle {\\phi} between the two phenyl rings, and hence the degree of\n{\\pi} conjugation, is controlled by alkyl chains and methyl side groups. We\nconsider three different coordination geometries, namely top-top,\nbridge-bridge, and hollow-hollow with the terminal sulfur atoms bound to one,\ntwo, and three gold surface atoms, respectively. Our calculations show that\ndifferent coordination geometries give rise to conductances which vary by one\norder of magnitude for the same molecule. Irrespective of the coordination\ngeometries, the charge transport calculations predict a cos^{2}{\\phi}\ndependence of the conductance, which is confirmed by our experimental\nmeasurements. We observe that the calculated transmission through biphenyl\ndithiols is typically dominated by a single transmission eigenchannel formed\nfrom {\\pi} electrons. Only for a single molecule with a completely broken\nconjugation we find a perfect channel degeneracy for the hollow-hollow-type\ncontact in our theory."
    },
    {
        "anchor": "Quantum Transport in Graphene Nanoribbons with Realistic Edges: Due to their unique electrical properties, graphene nanoribbons (GNRs) show\ngreat promise as the building blocks of novel electronic devices. However,\nthese properties are strongly dependent on the geometry of the edges of the\ngraphene devices. Thus far only zigzag and armchair edges have been extensively\nstudied. However, several other self passivating edge reconstructions are\npossible, and were experimentally observed. Here we utilize the Nonequilibrium\nGreen's Function (NEGF) technique in conjunction with tight binding methods to\nmodel quantum transport through armchair, zigzag, and several other\nself-passivated edge reconstructions. In addition we consider the\nexperimentally relevant cases of mixed edges, where random combinations of\npossible terminations exist on a given GNR boundary. We find that transport\nthrough GNR's with self-passivating edge reconstructions is governed by the\nsublattice structure of the edges, in a manner similar to their parent zigzag\nor armchair configurations. Furthermore, we find that the reconstructed\narmchair GNR's have a larger band gap energy than pristine armchair edges and\nare more robust against edge disorder. These results offer novel insights into\nthe transport in GNRs with realistic edges and are thus of paramount importance\nin the development of GNR based devices.",
        "positive": "How nonlocal damping reduces plasmon-enhanced fluorescence in\n  ultranarrow gaps: The nonclassical modification of plasmon-assisted fluorescence enhancement is\ntheoretically explored by placing two-level dipole emitters at the narrow gaps\nencountered in canonical plasmonic architectures, namely dimers and trimers of\ndifferent metallic nanoparticles. Through detailed simulations, in comparison\nwith appropriate analytical modelling, it is shown that within classical\nelectrodynamics, and for the reduced separations explored here, fluorescence\nenhancement factors of the order of $10^{5}$ can be achieved, with a divergent\nbehaviour as the particle touching regime is approached. This remarkable\nprediction is mainly governed by the dramatic increase in excitation rate\ntriggered by the corresponding field enhancement inside the gaps. Nevertheless,\nonce nonclassical corrections are included, the amplification factors decrease\nby up to two orders of magnitude and a saturation regime for narrower gaps is\nreached. These nonclassical limitations are demonstrated by simulations based\non the generalised nonlocal optical response theory, which accounts in an\nefficient way not only for nonlocal screening, but also for the enhanced Landau\ndamping near the metal surface. A simple strategy to introduce nonlocal\ncorrections to the analytic solutions is also proposed. It is therefore shown\nthat the nonlocal optical response of the metal imposes more realistic, finite\nupper bounds to the enhancement feasible with ultrasmall plasmonic cavities,\nthus providing a theoretical description closer to state of the art\nexperiments."
    },
    {
        "anchor": "Using a tunable quantum wire to measure the large out-of-plane spin\n  splitting of quasi two-dimensional holes in a GaAs nanostructure: The out-of-plane g-factor g_perp for quasi-2D holes in a (100) GaAs\nheterostructure is studied using a variable width quantum wire. A direct\nmeasurement of the Zeeman splitting is performed in a magnetic field applied\nperpendicular to the 2D plane. We measure an out-of-plane g-factor up to g_perp\n= 5, which is larger than previous optical studies of g_perp, and is\napproaching the long predicted but never experimentally verified out-of-plane\ng-factor of 7.2 for heavy holes.",
        "positive": "Imaging and writing magnetic domains in the non-collinear\n  antiferromagnet Mn$_{\\text{3}}$Sn: Harnessing the unique properties of non-collinear antiferromagnets (AFMs)\nwill be essential for exploiting the full potential of antiferromagnetic\nspintronics. Indeed, many of the effects enabling ferromagnetic spintronic\ndevices have a corresponding counterpart in materials with non-collinear spin\nstructure. In addition, new phenomena such as the magnetic spin Hall effect\nwere experimentally observed in non-collinear AFMs, and the presence of the\nequivalent to the ferromagnetic spin transfer torque via spin polarized\ncurrents was theoretically predicted. In spite of these developments, an\ninterpretation of the rich physical phenomena observed in non-collinear\nantiferromagnets is challenging, since the microscopic spin arrangement, the\nmagnetic domain distribution, and the domain orientations have proven\nnotoriously difficult to access experimentally. This is all the more\nproblematic, as imaging and writing magnetic domains is of central importance\nfor applications. Successful imaging is a basic requirement to experimentally\nconfirm the spin transfer torque acting on non-collinear domain walls and\ntherefore of eminent interest. Here, we demonstrate that the local magnetic\nstructure of the non-collinear AFM Mn3Sn films can be imaged by scanning\nthermal gradient microscopy (STGM). The technique is based on scanning a laser\nspot over the sample's surface, and recording the ensuing thermo-voltage. We\nimage the magnetic structure at a series of different temperatures and show\nthat at room temperature, the domain structure is not affected by the\napplication of moderate magnetic fields. In addition to imaging, we establish a\nscheme for heat-assisted magnetic recording, using local laser heating in\ncombination with magnetic fields to intentionally write domain patterns into\nthe antiferromagnet."
    },
    {
        "anchor": "Electronic structure of wurtzite quantum dots with cylindrical symmetry: This paper presents a six-band k.p theory for wurtzite semiconductor\nnanostructures with cylindrical symmetry. Our work extends the formulation of\nVahala and Sercel [Physical Review Letters 65, 239 (1990)] to the\nRashba-Sheka-Pikus Hamiltonian for wurtzite semiconductors, without the need\nfor the axial approximation. Results comparing our formulation for studying the\nelectronic structure of wurzite quantum dots with the conventional formulation\nare given.",
        "positive": "Spin Superfluidity in the $\u03bd=0$ Quantum Hall State of Graphene: A proposal to detect the purported canted antiferromagnet order for the\n$\\nu=0$ quantum Hall state of graphene based on a two-terminal spin transport\nsetup is theoretically discussed. In the presence of a magnetic field normal to\nthe graphene plane, a dynamic and inhomogeneous texture of the N\\'eel vector\nlying within the plane should mediate (nearly dissipationless) superfluid\ntransport of spin angular momentum polarized along the $z$ axis, which could\nserve as a strong support for the canted antiferromagnet scenario. Spin\ninjection and detection can be achieved by coupling two spin-polarized edge\nchannels of the $|\\nu|=2$ quantum Hall state on two opposite ends of the\n$\\nu=0$ region. A simple kinetic theory and Onsager reciprocity are invoked to\nmodel the spin injection and detection processes, and the transport of spin\nthrough the antiferromagnet is accounted for using the Landau-Lifshitz-Gilbert\nphenomenology."
    },
    {
        "anchor": "Polaritons in two-dimensional parabolic waveguides: The suite of highly confined polaritons supported by two-dimensional (2D)\nmaterials constitutes a versatile platform for nano-optics, offering the means\nto channel light on deep-subwavelength scales. Graphene, in particular, has\nattracted considerable interest due to its ability to support long-lived\nplasmons that can be actively tuned via electrical gating. While the excellent\noptoelectronic properties of graphene are widely exploited in plasmonics, its\nmechanical flexibility remains relatively underexplored in the same context.\nHere, we present a semi-analytical formalism to describe plasmons and other\npolaritons supported in waveguides formed by bending a 2D material into a\nparabolic shape. Specifically, for graphene parabolas, our theory reveals that\nthe already large field confinement associated with graphene plasmons can be\nsubstantially increased by bending an otherwise flat graphene sheet into a\nparabola shape, thereby forming a plasmonic waveguide without introducing\npotentially lossy edge terminations via patterning. Further, we show that the\nhigh field confinement associated with such channel polaritons in 2D parabolic\nwaveguides can enhance the spontaneous emission rate of a quantum emitter near\nthe parabola vertex. Our findings apply generally to 2D polaritons in\natomically thin materials deposited onto grooves or wedges prepared on a\nsubstrate or freely suspended in a quasi-parabolic (catenary) shape. We\nenvision that both the optoelectronic and mechanical flexibility of 2D\nmaterials can be harnessed in tandem to produce 2D channel polaritons with\nversatile properties that can be applied to a wide range of nano-optics\nfunctionalities, including subwavelength polaritonic circuitry and bright\nsingle-photon sources.",
        "positive": "Undoped Electron-Hole Bilayers in a GaAs/AlGaAs Double Quantum Well: We present the fabrication details of completely undoped electron-hole\nbilayer devices in a GaAs/AlGaAs double quantum well heterostructure with a 30\nnm barrier. These devices have independently tunable densities of the\ntwo-dimensional electron gas and two-dimensional hole gas. We report\nfour-terminal transport measurements of the independently contacted electron\nand hole layers with balanced densities from $1.2 \\times 10^{11}$cm$^{-2}$ down\nto $4 \\times 10^{10}$ cm$^{-2}$ at $T = 300 mK$. The mobilities can exceed $1\n\\times 10^{6}$ cm$^{2}$ V$^{-1}$ s$^{-1}$ for electrons and $4 \\times 10^{5}$\ncm$^{2}$ V$^{-1}$ s$^{-1}$ for holes."
    },
    {
        "anchor": "Non-linear electromagnetic response of graphene: It is shown that the massless energy spectrum of electrons and holes in\ngraphene leads to the strongly non-linear electromagnetic response of this\nsystem. We predict that the graphene layer, irradiated by electromagnetic\nwaves, emits radiation at higher frequency harmonics and can work as a\nfrequency multiplier. The operating frequency of the graphene frequency\nmultiplier can lie in a broad range from microwaves to the infrared.",
        "positive": "Generation and detection of mode-locked spin coherence in (In,Ga)As/GaAs\n  quantum dots by laser pulses of long duration: Using optical pulses of variable duration up to 80 ps, we report on spin\ncoherence initialization and its subsequent detection in n-type singly-charged\nquantum dots, subject to a transverse magnetic field, by pump-probe techniques.\nWe demonstrate experimentally and theoretically that the spin coherence\ngeneration and readout efficiencies are determined by the ratio of laser pulse\nduration to spin precession period: An increasing magnetic field suppresses the\nspin coherence signals for a fixed duration of pump and/or probe pulses, and\nthis suppression occurs for smaller fields the longer the pulse duration is.\nThe reason for suppression is the varying spin orientation due to precession\nduring pulse action."
    },
    {
        "anchor": "Theory of Conductivity of Chiral Particles: In this methodology focused paper we scrutinize the application of the\nband-coherent Boltzmann equation approach to calculating the conductivity of\nchiral particles. As the ideal testing ground we use the two-band kinetic\nHamiltonian with an N-fold chiral twist that arise in a low-energy description\nof charge carriers in rhombohedrally stacked multilayer graphene. To understand\nthe role of chirality in the conductivity of such particles we also consider\nthe artificial model with the chiral winding number decoupled from the power of\nthe dispersion. We first utilize the approximate but analytically solvable\nband-coherent Boltzmann approach including the ill-understood principal value\nterms that are a byproduct of several quantum-many body theory derivations of\nBoltzmann collision integrals. Further on, we employ the finite-size Kubo\nformula with the exact diagonalization of the total Hamiltonian perturbed by\ndisorder. Finally, we compare several choices of Ansatz in the derivation of\nthe Boltzmann equation according to the qualitative agreement between the\nBoltzmann and Kubo conductivities. We find that the best agreement can be\nreached in the approach where the principle value terms in the collision\nintegral are absent.",
        "positive": "Quantum-anomalous-Hall current patterns and interference in thin slabs\n  of chiral topological superconductors: The chiral topological superconductor, which supports propagating nontrivial\nedge modes while maintaining a gapped bulk, can be realized hybridizing a\nquantum-anomalous-Hall thin slab with an ordinary $s$-wave superconductor. We\nshow that by sweeping the voltage bias in a normal-hybrid-normal double\njunction, the pattern of electric currents in the normal leads spans three main\nregimes. From single-mode edge-current quantization at low bias, to double-mode\nedge-current oscillations at intermediate voltages and up to diffusive bulk\ncurrents at larger voltages. Observing such patterns by resolving the spatial\ndistribution of the local current in the thin slab could provide additional\nevidence, besides the global conductance, on the physics of chiral topological\nsuperconductors."
    },
    {
        "anchor": "Electron-nuclear coherent spin oscillations probed by spin dependent\n  recombination: We demonstrate the detection of coherent electron-nuclear spin oscillations\nrelated to the hyperfine interaction and revealed by the band-to-band\nphotoluminescence (PL) in zero external magnetic field. On the base of a\npump-probe PL experiment we measure, directly in the temporal domain, the\nhyperfine constant of an electron coupled to a gallium defect in GaAsN by\ntracing the dynamical behavior of the conduction electron spin-dependent\nrecombination to the defect site. The hyperfine constants and the relative\nabundance of the nuclei isotopes involved can be determined without the need of\nelectron spin resonance technique and in the absence of any magnetic field.\nInformation on the nuclear and electron spin relaxation damping parameters can\nalso be estimated from the oscillations damping and the long delay behavior.",
        "positive": "Observation of Quantum-Tunneling Modulated Spin Texture in Ultrathin\n  Topological Insulator Bi2Se3 Films: Understanding the spin-texture behavior of boundary modes in ultrathin\ntopological insulator films is critically essential for the design and\nfabrication of functional nano-devices. Here by using spin-resolved\nphotoemission spectroscopy with p-polarized light in topological insulator\nBi2Se3 thin films, we report tunneling-dependent evolution of spin\nconfiguration in topological insulator thin films across the metal-to-insulator\ntransition. We observe strongly binding energy- and wavevector-dependent spin\npolarization for the topological surface electrons in the ultra-thin\ngapped-Dirac-cone limit. The polarization decreases significantly with enhanced\ntunneling realized systematically in thin insulating films, whereas magnitude\nof the polarization saturates to the bulk limit faster at larger wavevectors in\nthicker metallic films. We present a theoretical model which captures this\ndelicate relationship between quantum tunneling and Fermi surface spin\npolarization. Our high-resolution spin-based spectroscopic results suggest that\nthe polarization current can be tuned to zero in thin insulating films forming\nthe basis for a future spin-switch nano-device."
    },
    {
        "anchor": "Quantum thermodynamics of the driven resonant level model: We present a consistent thermodynamic theory for the resonant level model in\nthe wide band limit, whose level energy is driven slowly by an external force.\nThe problem of defining 'system' and 'bath' in the strong coupling regime is\ncircumvented by considering as the 'system' everything that is influenced by\nthe externally driven level. The thermodynamic functions that are obtained to\nfirst order beyond the quasistatic limit fulfill the first and second law with\na positive entropy production, successfully connect to the forces experienced\nby the external driving, and reproduce the correct weak coupling limit of\nstochastic thermodynamics.",
        "positive": "Effect of Many Modes on Self-Polarization and Photochemical Suppression\n  in Cavities: The standard description of cavity-modified molecular reactions typically\ninvolves a single (resonant) mode, while in reality the quantum cavity supports\na range of photon modes. Here we demonstrate that as more photon modes are\naccounted for, physico-chemical phenomena can dramatically change, as\nillustrated by the cavity-induced suppression of the important and ubiquitous\nprocess of proton-coupled electron-transfer. Using a multi-trajectory Ehrenfest\ntreatment for the photon-modes, we find that self-polarization effects become\nessential, and we introduce the concept of self-polarization-modified\nBorn-Oppenheimer surfaces as a new construct to analyze dynamics. As the number\nof cavity photon modes increases, the increasing deviation of these surfaces\nfrom the cavity-free Born-Oppenheimer surfaces, together with the interplay\nbetween photon emission and absorption inside the widening bands of these\nsurfaces, leads to enhanced suppression. The present findings are general and\nwill have implications for the description and control of cavity-driven\nphysical processes of molecules, nanostructures and solids embedded in\ncavities."
    },
    {
        "anchor": "Graphene Spin Transistor: Graphitic nanostructures, e.g. carbon nanotubes (CNT) and graphene, have been\nproposed as ideal materials for spin conduction[1-7]; they have long electronic\nmean free paths[8] and small spin-orbit coupling[9], hence are expected to have\nvery long spin-scattering times. In addition, spin injection and detection in\ngraphene opens new opportunities to study exotic electronic states such as the\nquantum Hall[10,11] and quantum spin Hall[9] states, and spin-polarized edge\nstates[12] in graphene ribbons. Here we perform the first non-local four-probe\nexperiments[13] on graphene contacted by ferromagnetic Permalloy electrodes. We\nobserve sharp switching and often sign-reversal of the non-local resistance at\nthe coercive field of the electrodes, indicating definitively the presence of a\nspin current between injector and detector. The non-local resistance changes\nmagnitude and sign quasi-periodically with back-gate voltage, and\nFabry-Perot-like oscillations[6,14,15] are observed, consistent with\nquantum-coherent transport. The non-local resistance signal can be observed up\nto at least T = 300 K.",
        "positive": "Hierarchical equations of motion approach to hybrid fermionic and\n  bosonic environments: Matrix product state formulation in twin space: We extend the twin-space formulation of the hierarchical equations of motion\napproach in combination with the matrix product state representation\n(introduced in J. Chem. Phys. 150, 234102, [2019]) to nonequilibrium scenarios\nwhere the open quantum system is coupled to a hybrid fermionic and bosonic\nenvironment. The key ideas used in the extension are a reformulation of the\nhierarchical equations of motion for the auxiliary density matrices into a\ntime-dependent Schr\\\"odinger-like equation for an augmented multi-dimensional\nwave function as well as a tensor decomposition into a product of low-rank\nmatrices. The new approach facilitates accurate simulations of non-equilibrium\nquantum dynamics in larger and more complex open quantum systems. The\nperformance of the method is demonstrated for a model of a molecular junction\nexhibiting current-induced mode-selective vibrational excitation."
    },
    {
        "anchor": "Reservoir-engineered entanglement in optomechanical systems: We show how strong steady-state entanglement can be achieved in a three-mode\noptomechanical system (or other parametrically-coupled bosonic system) by using\none of the modes as a cold reservoir to effectively laser-cool a delocalized\nBogoliubov mode. This approach allows one to surpass the bound on the maximum\nstationary intracavity entanglement possible with a coherent two-mode squeezing\ninteraction. Unlike typical dissipative entanglement schemes, the entangling\ndynamics here are most effective in a regime where the effects of the\nengineered reservoir cannot be described by a Markovian Lindblad master\nequation.",
        "positive": "Quantitative modeling of superconducting planar resonators with improved\n  field homogeneity for electron spin resonance: We present three designs for planar superconducting microwave resonators for\nelectron spin resonance (ESR) experiments. We implement finite element\nsimulations to calculate the resonance frequency and quality factors as well as\nthe three-dimensional microwave magnetic field distribution of the resonators.\nOne particular resonator design offers an increased homogeneity of the\nmicrowave magnetic field while the other two show a better confinement of the\nmode volume. We extend our model simulations to calculate the collective\ncoupling rate between a spin ensemble and a microwave resonator in the presence\nof an inhomogeneous magnetic resonator field. Continuous-wave ESR experiments\nof phosphorus donors in $^\\mathrm{nat}$Si demonstrate the feasibility of our\nresonators for magnetic resonance experiments. We extract the collective\ncoupling rate and find a good agreement with our simulation results,\ncorroborating our model approach. Finally, we discuss specific application\ncases for the different resonator designs."
    },
    {
        "anchor": "Magnetoresistance in a soft billiard: giant peak near the percolation\n  threshold: By numerical simulation, we study the classical magnetoresistance of\ntwo-dimensional electrons in the presence of weak short range scattering. A\ncritical magnetic field defines the percolation threshold, above which the\nlongitudinal resistance vanishes. Unexpectedely, just below this threshold we\nfind a shrp narrow peak, where the resistance may increase 15 times compared to\nits zero-field value. By considering the complex topology of the effective\npotential landscape for the center of the cyclotron circle, we show that this\nphenomenon is related to infinite equipotential lines, which exists only in a\nnarrow magnetic field interval below the percolation threshold",
        "positive": "Gate-modulated conductance of few-layer WSe_2 field-effect transistors\n  in the subgap regime: Schottky barrier transistor and subgap impurity states: Two key subjects stand out in the pursuit of semiconductor research: material\nquality and contact technology. The fledging field of atomically thin\ntransition metal dichalcogenides (TMDCs) faces a number of challenges in both\nefforts. This work attempts to establish a connection between the two by\nexamining the gate-dependent conductance of few-layer (1-5L) WSe2 field effect\ndevices. Measurements and modeling of the subgap regime reveal Schottky barrier\ntransistor behavior. We show that transmission through the contact barrier is\ndominated by thermionic field emission (TFE) at room temperature, despite the\nlack of intentional doping. The TFE process arises due to a large number of\nsubgap impurity states, the presence of which also leads to high mobility edge\ncarrier densities. The density of states of such impurity states is\nself-consistently determined to be approximately 1-2x10^13 /cm^2/eV in our\ndevices. We demonstrate that substrate is unlikely to be a major source of the\nimpurity states and suspect that lattice defects within the material itself are\nprimarily responsible. Our experiments provide key information to advance the\nquality and understanding of TMDC materials and electrical devices."
    },
    {
        "anchor": "Two-Qubit Pulse Gate for the Three-Electron Double Quantum Dot Qubit: The three-electron configuration of gate-defined double quantum dots encodes\na promising qubit for quantum information processing. I propose a two-qubit\nentangling gate using a pulse-gated manipulation procedure. The requirements\nfor high-fidelity entangling operations are equivalent to the requirements for\nthe pulse-gated single-qubit manipulations that have been successfully realized\nfor Si QDs. This two-qubit gate completes the universal set of all-pulse-gated\noperations for the three-electron double-dot qubit and paves the way for a\nscalable setup to achieve quantum computation.",
        "positive": "Excitonic Rayleigh scattering spectra of metallic single-walled carbon\n  nanotubes: We have performed microscopic calculations of the Rayleigh scattering cross\nsection for arbitrary metallic single-walled carbon nanotubes. The focus of our\ninvestigations lies on excitonic effects and their influence on the\ncharacteristic features in a Rayleigh scattering spectrum. Our approach is\nbased on density matrix theory including tight-binding energies, the\ncarrier-light coupling as well as the carrier-carrier interaction. Due to the\nrefractive index contribution to the scattering cross section, we observe\ncharacteristic features in Rayleigh spectra, such as a strong deviation from\nthe Lorentz peak shape and the larger oscillator strength of the lower-lying\ntransition $M_{ii}^-$ in the double-peaked structure, independently of the\nchiral angle and the diameter of the investigated nanotubes. We observe\nexcitonic binding energies in the range of $\\unit[60-80]{meV}$ for metallic\nnanotubes with diameters of $\\unit[1.5-2.5]{nm}$. The overlap of the excitonic\ntransition with the close-by continuum has a significant influence on the peak\nshape and a minor influence on the peak intensity ratios. The presented results\nare in good agreement with recent experimental data."
    },
    {
        "anchor": "Observation of Giant Orbital Magnetic Moments and Paramagnetic Shift in\n  Artificial Relativistic Atoms and Molecules: Massless Dirac fermions have been observed in various materials such as\ngraphene and topological insulators in recent years, thus offering a\nsolid-state platform to study relativistic quantum phenomena. Single quantum\ndots (QDs) and coupled QDs formed with massless Dirac fermions can be viewed as\nartificial relativistic atoms and molecules, respectively. Such structures\noffer a unique platform to study atomic and molecular physics in the\nultra-relativistic regime. Here, we use a scanning tunneling microscope to\ncreate and probe single and coupled electrostatically defined graphene QDs to\nunravel the unique magnetic field responses of artificial relativistic\nnanostructures. Giant orbital Zeeman splitting and orbital magnetic moment are\nobserved in single graphene QDs. While for coupled graphene QDs, Aharonov Bohm\noscillations and strong Van Vleck paramagnetic shift are observed. Such\nproperties of artificial relativistic atoms and molecules can be leveraged for\nnovel magnetic field sensing modalities.",
        "positive": "The Hanbury Brown and Twiss Experiment with Fermions: We realized an equivalent Hanbury Brown and Twiss experiment for a beam of\nelectrons in a two dimensional electron gas in the quantum Hall regime. A\nmetallic split gate serves as a tunable beam splitter which is used to\npartition the incident beam into transmitted and reflected partial beams. The\ncurrent fluctuations in the reflected and transmitted beam are fully\nanticorrelated demonstrating that fermions tend to exclude each other\n(anti-bunching). If the occupation probability of the incident beam is lowered\nby an additional gate, the anticorrelation is reduced and disappears in the\nclassical limit of a highly diluted beam."
    },
    {
        "anchor": "Spin-Orbit-Induced Spin, Charge, and Energy Transport in Diffusive\n  Superconductors: We consider the spin-orbit-induced spin Hall effect and spin swapping in\ndiffusive superconductors. By employing the non-equilibrium Keldysh Green's\nfunction technique in the quasiclassical approximation, we derive coupled\ntransport equations for the spectral spin and particle distributions and for\nthe energy density in the elastic scattering regime. We compute four\ncontributions to the spin Hall conductivity, namely, skew scattering,\nside-jump, anomalous velocity, and the Yafet contribution. The reduced density\nof states in the superconductor causes a renormalization of the spin Hall\nangle. We demonstrate that all four of these contributions to the spin Hall\nconductivity are renormalized in the same way in the superconducting state. In\nits simplest manifestation, spin swapping transforms a primary spin current\ninto a secondary spin current with swapped current and polarization directions.\nWe find that the spin-swapping coefficient is not explicitly but only\nimplicitly affected by superconducting correlations through the renormalized\ndiffusion coefficients. We discuss experimental consequences for measurements\nof the (inverse) spin Hall effect and spin swapping in four-terminal\ngeometries. In our geometry, below the superconducting transition temperature,\nthe spin-swapping signal is increased an order of magnitude while changes in\nthe (inverse) spin Hall signal are moderate.",
        "positive": "Layer-resolved conductivities in multilayer graphenes: We study interlayer transport of multilayer graphenes in magnetic field with\nvarious stacking structures (AB, ABC, and AA types) by calculating the Hall and\nlongitudinal conductivities as functions of Fermi energy. Their behavior\ndepends strongly on the stacking structures and selection of the layers. The\nHall conductivity between different layers is no longer quantized. Moreover,\nfor AB stacking, the interlayer conductivity vanishes around zero energy with\nincreasing layer separation, and shows negative values in particular cases. The\nfact that longitudinal interlayer conductivity suppressed by the magnetic field\nindicates that this system can be applied as a switching device."
    },
    {
        "anchor": "Quantum Hall Conductivity in a Landau Type Model with a Realistic\n  Geometry: In this paper, we revisit some quantum mechanical aspects related to the\nQuantum Hall Effect. We consider a Landau type model, paying a special\nattention to the experimental and geometrical features of Quantum Hall\nexperiments. The resulting formalism is then used to compute explicitely the\nHall conductivity from a Kubo formula.",
        "positive": "Distribution function of persistent current: We introduce a variant of the replica trick within the nonlinear sigma model\nthat allows calculating the distribution function of the persistent current. In\nthe diffusive regime, a Gaussian distribution is derived. This result holds in\nthe presence of local interactions as well. Breakdown of the Gaussian\nstatistics is predicted for the tails of the distribution function at large\ndeviations."
    },
    {
        "anchor": "Kinetic Monte Carlo model of epitaxial graphene growth: In this thesis we present a kinetic Monte Carlo model for the description of\nepitaxial graphene growth. Experimental results suggest a growth mechanism by\nwhich clusters of 5 carbon atoms are an intermediate species necessary for\nnucleation and island growth. This model is proposed by experimentally studying\nthe velocity of growth of islands which is a highly nonlinear function of\nadatom concentration. In our simulation we incorporate this intermediate\nspecies and show that it can explain all other experimental observations: the\ntemperature dependence of the adatom nucleation density, the equilibrium adatom\ndensity and the temperature dependence of the equilibrium island density. All\nthese processes are described only by the kinematics of the system.",
        "positive": "Qubit dephasing due to Quasiparticle Tunneling: We study dephasing of a superconducting qubit due to quasiparticle tunneling\nthrough a Josephson junction. While qubit decay due to tunneling processes is\nwell understood within a golden rule approximation, pure dephasing due to BCS\nquasiparticles gives rise to a divergent golden rule rate. We calculate qubit\ndephasing due to quasiparticle tunneling beyond lowest order approximation in\ncoupling between qubit and quasiparticles. Summing up a certain class of\ndiagrams we show that qubit dephasing due to purely longitudinal coupling to\nquasiparticles leads to a dephasing $\\sim \\exp(-x(t))$ where $x(t)$ is not\nlinear in time on short time scales while it tends towards a selfconsistent\ncalculated dephasing rate for longer times."
    },
    {
        "anchor": "Direct versus indirect band gap emission and exciton-exciton\n  annihilation in atomically thin molybdenum ditelluride (MoTe$_2$): We probe the room temperature photoluminescence of $N$-layer molybdenum\nditelluride (MoTe$_2$) in the continuous wave (cw) regime. The\nphotoluminescence quantum yield of monolayer MoTe$_2$ is three times larger\nthan in bilayer MoTe$_2$ and forty times greater than in the bulk limit. Mono-\nand bilayer MoTe$_2$ display almost symmetric emission lines at $1.10~\\rm eV$\nand $1.07~\\rm eV$, respectively, which predominantly arise from direct\nradiative recombination of the A exciton. In contrast, $N\\geq3-$layer MoTe$_2$\nexhibits a much reduced photoluminescence quantum yield and a broader,\nredshifted and seemingly bimodal photoluminescence spectrum. The low- and\nhigh-energy contributions are attributed to emission from the indirect and\ndirect optical band gaps, respectively. Bulk MoTe$_2$ displays a broad emission\nline with a dominant contribution at 0.94~eV that is assigned to emission from\nthe indirect optical band gap. As compared to related systems (such as MoS$_2$,\nMoSe$_2$, WS$_2$ and WSe$_2$), the smaller energy difference between the\nmonolayer direct optical band gap and the bulk indirect optical band gap leads\nto a smoother increase of the photoluminescence quantum yield as $N$ decreases.\nIn addition, we study the evolution of the photoluminescence intensity in\nmonolayer MoTe$_2$ as a function of the exciton formation rate $W_\\mathrm{abs}$\nup to $3.6\\times 10^{22}~\\rm{cm}^{-2} s^{-1}$. The lineshape of the\nphotoluminescence spectrum remains largely independent of $W_\\mathrm{abs}$,\nwhereas the photoluminescence intensity grows sub-linearly above\n$W_\\mathrm{abs}\\sim 10^{21}~\\rm cm^{-2} s^{-1}$. This behavior is assigned to\nexciton-exciton annihilation and is well-captured by an elementary rate\nequation model.",
        "positive": "Stark Effects of Rydberg Excitons in a Monolayer WSe2 P-N Junction: The enhanced Coulomb interaction in two-dimensional (2D) semiconductors leads\nto the tightly bound electron-hole pairs known as excitons. The large binding\nenergy of excitons enables the formation of Rydberg excitons with high\nprincipal quantum numbers (n), analogous to Rydberg atoms. Rydberg excitons\npossess strong interactions among themselves, as well as sensitive responses to\nexternal stimuli. Here, we probe Rydberg exciton resonances through\nphotocurrent spectroscopy in a monolayer WSe2 p-n junction formed by a\nsplit-gate geometry. We show that an external in-plane electric field not only\ninduces a large Stark shift of Rydberg excitons up to quantum principal number\nn=3 but also mixes different orbitals and brightens otherwise dark states such\nas 3p and 3d. Our study provides an exciting platform for engineering Rydberg\nexcitons for new quantum states and quantum sensing."
    },
    {
        "anchor": "Two topologically distinct Dirac-line semimetal phases and topological\n  phase transitions in rhombohedrally stacked honeycomb lattices: Three-dimensional topological semimetals can support band crossings along\none-dimensional curves in the momentum space (nodal lines or Dirac lines)\nprotected by structural symmetries and topology. We consider rhombohedrally\n(ABC) stacked honeycomb lattices supporting Dirac lines protected by\ntime-reversal, inversion and spin rotation symmetries. For typical band\nstructure parameters there exists a pair of nodal lines in the momentum space\nextending through the whole Brillouin zone in the stacking direction. We show\nthat these Dirac lines are topologically distinct from the usual Dirac lines\nwhich form closed loops inside the Brillouin zone. In particular, an energy gap\ncan be opened only by first merging the Dirac lines going through the Brillouin\nzone in a pairwise manner so that they turn into closed loops inside the\nBrillouin zone, and then by shrinking these loops into points. We show that\nthis kind of topological phase transition can occur in rhombohedrally stacked\nhoneycomb lattices by tuning the ratio of the tunneling amplitudes in the\ndirections perpendicular and parallel to the layers. We also discuss the\nproperties of the surface states in the different phases of the model.",
        "positive": "Angular dependence and symmetry of Rashba spin torque in ferromagnetic\n  heterostructures: In a ferromagnetic heterostructure, the interplay between a Rashba spin-orbit\ncoupling and an exchange field gives rise to a current-driven spin torque. In a\nrealistic device setup, we investigate the Rashba spin torque in the diffusive\nregime and report two major findings: (i) a nonvanishing torque exists at the\nedges of the device even when the magnetization and effective Rashba field are\naligned; (ii) anisotropic spin relaxation rates driven by the Rashba spin-orbit\ncoupling assign the spin torque a general expression ${\\bm\nT}=T^y_{\\para}(\\theta){\\bm m}\\times(\\hat{\\bm y}\\times{\\bm\nm})+T^y_{\\bot}(\\theta)\\hat{\\bm y}\\times{\\bm m}+T^z_{\\para}(\\theta){\\bm\nm}\\times(\\hat{\\bm z}\\times{\\bm m})+T^z_{\\bot}(\\theta)\\hat{\\bm z}\\times{\\bm m}$,\nwhere the coefficients $T_{\\para,\\bot}^{y,z}$ depend on the magnetization\ndirection. Our results agree with recent experiments."
    },
    {
        "anchor": "Quantum theory of multimode polariton condensation: We develop a theory for the dynamics of the density matrix describing a\nmultimode polariton condensate. In such a condensate several single-particle\norbitals become highly occupied, due to stimulated scattering from reservoirs\nof high-energy excitons. A generic few-parameter model for the system leads to\na Lindblad equation which includes saturable pumping, decay, and condensate\ninteractions. We show how this theory can be used to obtain the population\ndistributions, and the time-dependent first- and second-order coherence\nfunctions, in such a multimode condensate. As a specific application, we\nconsider a polaritonic Josephson junction, formed from a double-well potential.\nWe obtain the population distributions, emission line shapes, and widths\n(first-order coherence functions), and predict the dephasing time of the\nJosephson oscillations.",
        "positive": "A new kind of 2D topological insulators BiCN with a giant gap and its\n  substrate effects: Based on DFT calculation, we predict that BiCN, i.e., bilayer Bi films\npassivated with -CN group, is a novel 2D Bi-based material with highly\nthermodynamic stability, and demonstrate that it is also a new kind of 2D TI\nwith a giant SOC gap (? 1 eV) by direct calculation of the topological\ninvariant Z2 and obvious exhibition of the helical edge states. Monolayer h-BN\nand MoS2 are identified as good candidate substrates for supporting the\nnontrivial topological insulating phase of the 2D TI films, since the two\nsubstrates can stabilize and weakly interact with BiCN via van derWaals\ninteraction and thus hardly affect the electronic properties, especially the\nband topology. The topological properties are robust against the strain and\nelectric field. This may provide a promising platform for realization of novel\ntopological phases."
    },
    {
        "anchor": "Role of electron back action on photons in hybridizing double-layer\n  graphene plasmons with localized photons: Induced polarization by Dirac electrons in double-layer graphene can affect\nhybridization of radiative and evanescent fields. Electron back action appears\nas a localized optical field to modify an incident surface-plasmon-polariton\n(SPP) evanescent field. This leads to high sensitivity (beyond the diffraction\nlimit) to local environments and provides a scrutiny tool for molecules or\nprotein selectively bounded with carbon. A scattering matrix with frequencies\naround the surface-plasmon (SP) resonance supports this scrutiny tool and\nexhibits sensibly the increase, decrease and even a full suppression of the\npolarization field in the vicinity of a conducting surface for longer SPP\nwavelengthes. Moreover, triply-hybridized absorption peaks associated with SP,\nacoustic- and optical-like graphene plasmons become significant only at high SP\nfrequencies, but are overshadowed by a round SPP peak for low SP frequencies.\nThese resonant features (different from 3D photonic lattices) facilitate the\npolariton-only excitations, giving rise to possible polariton condensation for\na threshold-free laser. The current graphene-plasmon hybridization formalism\ncan be easily generalized to other two-dimensional materials, such as silicene,\ngermanene, molybdenum disulfide, etc.",
        "positive": "Orbital contributions to the electron g-factor in semiconductor\n  nanowires: Recent experiments on Majorana fermions in semiconductor nanowires [Albrecht\net al., Nat. 531, 206 (2016)] revealed a surprisingly large electronic Land\\'e\ng-factor, several times larger than the bulk value - contrary to the\nexpectation that confinement reduces the g-factor. Here we assess the role of\norbital contributions to the electron g-factor in nanowires and quantum dots.\nWe show that an LS coupling in higher subbands leads to an enhancement of the\ng-factor of an order of magnitude or more for small effective mass\nsemiconductors. We validate our theoretical finding with simulations of InAs\nand InSb, showing that the effect persists even if cylindrical symmetry is\nbroken. A huge anisotropy of the enhanced g-factors under magnetic field\nrotation allows for a straightforward experimental test of this theory."
    },
    {
        "anchor": "Layer-dependent pressure effect on electronic structures of 2D black\n  phosphorus: Through infrared spectroscopy, we systematically study the pressure effect on\nelectronic structures of few-layer black phosphorus (BP) with layer number\nranging from 2 to 13. We reveal that the pressure-induced shift of optical\ntransitions exhibits strong layer-dependence. In sharp contrast to the bulk\ncounterpart which undergoes a semiconductor to semimetal transition under ~1.8\nGPa, the bandgap of 2 L increases with increasing pressure until beyond 2 GPa.\nMeanwhile, for a sample with a given layer number, the pressure-induced shift\nalso differs for transitions with different indices. Through the tight-binding\nmodel in conjunction with a Morse potential for the interlayer coupling, this\nlayer- and transition-index-dependent pressure effect can be fully accounted.\nOur study paves a way for versatile van der Waals engineering of\ntwo-dimensional BP.",
        "positive": "Multifractality at the spin quantum Hall transition: Statistical properties of critical wave functions at the spin quantum Hall\ntransition are studied both numerically and analytically (via mapping onto the\nclassical percolation). It is shown that the index $\\eta$ characterizing the\ndecay of wave function correlations is equal to 1/4, at variance with the\n$r^{-1/2}$ decay of the diffusion propagator. The multifractality spectra of\neigenfunctions and of two-point conductances are found to be\nclose-to-parabolic, $\\Delta_q\\simeq q(1-q)/8$ and $X_q\\simeq q(3-q)/4$."
    },
    {
        "anchor": "Effects of site asymmetry and valley mixing on Hofstadter-type spectra\n  of bilayer graphene in a square-scatter array potential: Under a magnetic field perpendicular to an monolayer graphene, the existence\nof a two-dimensional periodic scatter array can not only mix Landau levels of\nthe same valley for displaying split electron-hole Hofstadter-type energy\nspectra, but also couple two sets of Landau subbands from different valleys in\na bilayer graphene. Such a valley mixing effect with a strong scattering\nstrength has been found observable and studied thoroughly in this paper by\nusing a Bloch-wave expansion approach and a projected $2\\times 2$ effective\nHamiltonian including interlayer effective mass, interlayer coupling and\nasymmetrical on-site energies due to a vertically-applied electric field. For\nbilayer graphene, we find two important characteristics, i.e., mixing and\ninterference of intervalley scatterings in the presence of a scatter array, as\nwell as a perpendicular-field induced site-energy asymmetry which deforms\nseverely or even destroy completely the Hofstadter-type band structures due to\nthe dependence of Bloch-wave expansion coefficients on the applied electric\nfield.",
        "positive": "Comment on cond-mat/0409228 \"Microwave photoresponse in the 2D electron\n  system caused by intra-Landau level transitions\": We provide an article-extract which points out that a microwave-induced\nmodification in the resistance occurs at relatively \"high\" magnetic fields\nwhere the radiation is incapable of producing inter-Landau level excitations\nand, therefore, that the microwave radiation must be producing intra Landau\nlevel excitations as well."
    },
    {
        "anchor": "Image charge effects in single-molecule junctions: Breaking of\n  symmetries and negative differential resistance in a benzene transistor: Both experiments and theoretical studies have demonstrated that the\ninteraction between the current carrying electrons and the induced polarization\ncharge in single-molecule junctions leads to a strong renormalization of\nmolecular charging energies. However, the effect on electronic excitations and\nmolecular symmetries remain unclear. Using a theoretical framework developed\nfor semiconductor nanostructure based single-electron transistors (SETs), we\ndemonstrate that the image charge interaction breaks the molecular symmetries\nin a benzene based single-molecule transistor operating in the Coulomb blockade\nregime. This results in the appearance of a so-called blocking state, which\ngives rise to negative differential resistance (NDR). We show that the\nappearance of NDR and its magnitude in the symmetry-broken benzene SET depends\nin a complicated way on the interplay between the many-body matrix elements,\nthe lead tunnel coupling asymmetry, and the bias polarity. In particular, the\ncurrent reducing property of the blocking state causing the NDR, is shown to\nvanish under strongly asymmetric tunnel couplings, when the molecule is coupled\nstronger to the drain electrode. The calculated IV characteristic may serve as\nan indicator for image charge broken molecular symmetries in experimental\nsituations.",
        "positive": "Spin-charge coupling effects in a two-dimensional electron gas: In these lecture notes we study the disordered two-dimensional electron gas\nin the presence of Rashba spin-orbit coupling, by using the Keldysh\nnon-equilibrium Green function technique. We describe the effects of the\nspin-orbit coupling in terms of a SU(2) gauge field and derive a generalized\nBoltzmann equation for the charge and spin distribution functions. We then\napply the formalism to discuss the spin Hall and the inverse spin galvanic\n(Edelstein) effects. Successively we show how to include, within the\ngeneralized Boltzmann equation, the side jump, the skew scattering and the spin\ncurrent swapping processes originating from the extrinsic spin-orbit coupling\ndue to impurity scattering."
    },
    {
        "anchor": "Landau levels and snake states of pseudo-spin-1 Dirac-like electrons in\n  gapped Lieb lattices: This work reports the three-band structure associated with a Lieb lattice\nwith arbitrary nearest and next-nearest neighbors hopping interactions. For\nspecific configurations, the system admits a flat band located between two\ndispersion bands. Three inequivalent Dirac valleys are identified so that the\nquasi-particles are effectively described by the spin-1 Dirac-type equation.\nUnder external homogeneous magnetic fields, the Landau levels are exactly\ndetermined as the third-order polynomial equation for the energy can be solved\nusing Cardano's formula. It is also shown that an external anti-symmetric field\npromotes the existence of current-carrying states, so-called snake states,\nconfined at the interface where the external field changes its sign.",
        "positive": "Radial Spin Helix in Two-Dimensional Electron Systems with Rashba\n  Spin-Orbit Coupling: We suggest a long-lived spin polarization structure, a radial spin helix, and\nstudy its relaxation dynamics. For this purpose, starting with a simple and\nphysically clear consideration of spin transport, we derive a system of\nequations for spin polarization density and find its general solution in the\naxially symmetric case. It is demonstrated that the radial spin helix of a\ncertain period relaxes slower than homogeneous spin polarization and plain spin\nhelix. Importantly, the spin polarization at the center of the radial spin\nhelix stays almost unchanged at short times. At longer times, when the initial\nnon-exponential relaxation region ends, the relaxation of the radial spin helix\noccurs with the same time constant as that describing the relaxation of the\nplain spin helix."
    },
    {
        "anchor": "Interaction without back-action in the context of quantum manipulation: We address the interaction between two quantum systems (A and B) that is\nmediated by their common linear environment. If the environment is out of\nequilibrium the resulting interaction violates Onsager relations and cannot be\ndescribed by a Hamiltonian. In simple terms the action of system A on system B\ndoes not necessarily produce a back-action. We derive general quantum equations\ndescribing the situation and analyze in details their classical correspondence.\nChanging the properties of the environment one can easily change and engineer\nthe resulting interaction. It is tempting to use this for quantum manipulation\nof the systems. However the resulting quantum gate is not always unitary and\nmay induce a loss of quantum coherence. For a relevant example we consider\nsystems A and B to be spins of arbitrary values and arrange the interaction to\nrealize an analogue of the two-qubit CNOT gate. The direction of spin A\ncontrols the rotation of spin B while spin A is not rotated experiencing no\nback-action from spin B. We solve the quantum dynamics equations and analyze\nthe purity of the resulting density matrix. The resulting purity essentially\ndepends on the initial states of the systems. We attempt to find a universal\ncharacteristics of the purity optimizing it for the worst choice of initial\nstates. For both spins $s_A=s_B=1/2$, the optimized purity is bounded by 1/2\nirrespective of the details of the gate. We also study in detail the\nsemiclassical limit of large spins. In this case the optimized purity is\nbounded by $(1+\\pi/2)^{-1}\\approx0.39$. This is much better than the typical\npurity of a large spin state $\\sim s^{-1}$. We conclude that although the\nquantum manipulation without back-action inevitably causes decoherence of the\nquantum states the actual purity of the resulting state can be optimized and\nmade relatively high.",
        "positive": "Higher-order topology in honeycomb lattice with Y-Kekul\u00e9 distortions: We investigate higher-order topological states in honeycomb lattice with\nY-Kekul\\'e distortions that preserve $C_{6v}$ crystalline symmetry. The gapped\nstates in expanded and shrunken distortions are adiabatically connected to\nisolated hexamers and Y-shaped tetramer states, respectively, where the former\npossesses nontrivial higher-order topology characterized by a $\\mathbb{Z}_6$\ninvariant. Topological corner states exist in a flake structure with expanded\ndistortion where the hexamers are broken at the corners. Our work reveals that\nhoneycomb lattice with Y-Kekul\\'e distortions serves as a promising platform to\nstudy higher-order topological states."
    },
    {
        "anchor": "Two-dimensional spin-filtered chiral network model for the Z_2 quantum\n  spin-Hall effect: The effects of static disorder on the Z_2 quantum spin-Hall effect for\nnon-interacting electrons propagating in two-dimensional space is studied\nnumerically. A two-dimensional time-reversal symmetric network model is\nconstructed to account for the effects of static disorder on the propagation of\nnon-interacting electrons subjected to spin-orbit couplings. This network model\nis different from past network models belonging to the symplectic symmetry\nclass in that the propagating modes along the links of the network can be\narranged into an odd number of Kramers doublet. It is found that (1) a\ntwo-dimensional metallic phase of finite extent is embedded in a Z_2 insulating\nphase in parameter space and (2) the quantum phase transitions between the\nmetallic and Z_2 insulating phases belong to the conventional symplectic\nuniversality class in two space dimensions.",
        "positive": "Effects of different lead magnetizations on the Datta-Das spin\n  field-effect transistor: A Datta-Das spin field effect transistor is built of a one-dimensional weak\nlink, with Rashba spin orbit interactions (SOI), which connects two magnetized\nreservoirs. The particle and spin currents between the two reservoirs are\ncalculated to lowest order in the tunneling through the weak link and in the\nwide-band approximation, with emphasis on their dependence on the origins of\nthe `bare' magnetizations in the reservoirs. The SOI is found to generate\nmagnetization components in each reservoir, which rotate in the plane of the\nelectric field (generating the SOI) and the weak link, only if the `bare'\nmagnetization of the other reservoir has a non-zero component in that plane.\nThe SOI affects the charge current only if both reservoirs are polarized. The\ncharge current is conserved, but the transverse rotating magnetization current\nis not conserved since the SOI in the weak link generates extra spin\npolarizations which are injected into the reservoirs."
    },
    {
        "anchor": "Spectroscopic Signatures of Nonlocal Interfacial Coupling in\n  Superconducting FeSe/SrTiO3 Heterostructures: The mechanism of enhanced superconductivity in the one unit-cell (1UC) FeSe\nfilm on a SrTiO3 (STO) substrate has stimulated significant research interest\nbut remains elusive. Using low-temperature, voltage-gated Raman spectroscopy\nand low-temperature valence electron energy loss spectroscopy (VEELS), we\ncharacterize the phonon behavior and interfacial charge transfer in single- and\nfew-layer FeSe films on STO. Raman measurements reveal ambipolar softening of\nthe FeSe vibrational modes, mimicking that of the underlying STO substrate. We\nattribute this behavior to an interfacial coupling effect of STO on FeSe\nlattice dynamics. This interfacial coupling effect is further supported by\nlocal electron effective mass enhancement, which is determined from the\nred-shift in the FeSe VEELS spectrum near the FeSe/STO interface. Our work\nsheds light on the possible interfacial mechanisms contributing to the enhanced\nsuperconductivity across the FeSe/STO interface and further unveils the\npotential of low-temperature gated Raman spectroscopy and VEELS in clarifying a\nbroad category of quantum materials.",
        "positive": "Probing Layer Localization in Twisted Graphene Bilayers via Cyclotron\n  Resonance: Electron wavefunctions in twisted bilayer graphene may have a strong single\nlayer character or be intrinsically delocalized between layers, with their\nnature often determined by how energetically close they are to the Dirac point.\nIn this paper, we demonstrate that in magnetic fields, optical absorption\n(cyclotron resonance) spectra contain signatures which may be used to\ndistinguish the nature of these wavefunctions at low energies, as well as to\nlocate low energy critical points in the zero-field energy spectrum. Optical\nabsorption for two different configurations -- electric field parallel and\nperpendicular to the bilayer -- are calculated, which are shown to have\ndifferent selection rules with respect to which states are connected by the\nperturbation. Interlayer bias further distinguishes transitions involving\nstates of a single layer nature from those with support in both layers. For\ndoped systems, a sharp increase in intra-Landau level absorption occurs with\nincreasing field as the level passes through the zero-field saddle point\nenergy, where the states change character from single layer to bilayer."
    },
    {
        "anchor": "Coulomb drag in high Landau levels: Recent experiments on Coulomb drag in the quantum Hall regime have yielded a\nnumber of surprises. The most striking observations are that the Coulomb drag\ncan become negative in high Landau levels and that its temperature dependence\nis non-monotonous. We develop a systematic diagrammatic theory of Coulomb drag\nin strong magnetic fields explaining these puzzling experiments. The theory is\napplicable both in the diffusive and the ballistic regimes; we focus on the\nexperimentally relevant ballistic regime (interlayer distance $a$ smaller than\nthe cyclotron radius $R_c$). It is shown that the drag at strong magnetic\nfields is an interplay of two contributions arising from different sources of\nparticle-hole asymmetry, namely the curvature of the zero-field electron\ndispersion and the particle-hole asymmetry associated with Landau quantization.\nThe former contribution is positive and governs the high-temperature increase\nin the drag resistivity. On the other hand, the latter one, which is dominant\nat low $T$, has an oscillatory sign (depending on the difference in filling\nfactors of the two layers) and gives rise to a sharp peak in the temperature\ndependence at $T$ of the order of the Landau level width.",
        "positive": "Heat and charge transport in interacting nanoconductors driven by\n  time-modulated temperatures: We investigate the quantum transport of the heat and the charge through a\nquantum dot coupled to fermionic contacts under the influence of time\nmodulation of temperatures. We derive, within the nonequilibrium Keldysh\nGreen's function formalism, generic formulas for the charge and heat currents\nby extending the concept of gravitational field introduced by Luttinger to the\ndynamically driven system and by identifying the correct form of dynamical\ncontact energy. In linear response regime our formalism is validated from\nsatisfying the Onsager reciprocity relations and demonstrates its utility to\nreveal nontrivial dynamical effects of the Coulomb interaction on charge and\nenergy relaxations."
    },
    {
        "anchor": "Quantized electromagnetic response of three-dimensional chiral\n  topological insulators: Protected by the chiral symmetry, three dimensional chiral topological\ninsulators are characterized by an integer-valued topological invariant. How\nthis invariant could emerge in physical observables is an important question.\nHere we show that the magneto-electric polarization can identify the\ninteger-valued invariant if we gap the system without coating a quantum Hall\nlayer on the surface. The quantized response is demonstrated to be robust\nagainst weak perturbations. We also study the topological properties by\nadiabatically coupling two nontrivial phases, and find that gapless states\nappear and are localized at the boundary region. Finally, an experimental\nscheme is proposed to realize the Hamiltonian and measure the quantized\nresponse with ultracold atoms in optical lattices.",
        "positive": "Inelastic Effects in Low-Energy Electron Reflectivity of Two-dimensional\n  Materials: A simple method is proposed for inclusion of inelastic effects (electron\nabsorption) in computations of low-energy electron reflectivity (LEER) spectra.\nThe theoretical spectra are formulated by matching of electron wavefunctions\nobtained from first-principles computations in a repeated vacuum-slab-vacuum\ngeometry. Inelastic effects are included by allowing these states to decay in\ntime in accordance with an imaginary term in the potential of the slab, and by\nmixing of the slab states in accordance with the same type of distribution as\noccurs in a free-electron model. LEER spectra are computed for various\ntwo-dimensional materials, including free-standing multilayer graphene,\ngraphene on copper substrates, and hexagonal boron nitride (h-BN) on cobalt\nsubstrates."
    },
    {
        "anchor": "Electron transport signature of H$_2$ dissociation on atomic gold wires: Non-equilibrium Green's functions calculations based on density functional\ntheory show a direct link between the initial stages of H$_2$ dissociation on a\ngold atomic wire and the electronic current supported by the gold wire. The\nsimulations reveal that for biases below the stability threshold of the wire,\nthe minimum-energy path for H$_2$ dissociation is not affected. However, the\nelectronic current presents a dramatic drop when the molecule initiates its\ndissociation. This current drop is traced back to quantum interference between\nelectron paths when the molecule starts interacting with the gold wire.",
        "positive": "Revisiting thermal conductivity and interface conductance at the\n  nanoscale: A semi-analytical model for studying thermal transport at the nanoscale, able\nto accurately describe both the effect of out of equilibrium transport and the\nthermal transfer at interfaces, is presented. Our approach is based on the\ndefinition of pseudo local temperatures distinguishing the phonon populations\naccording to the direction of their velocity. This formalism leads to a\ncomplete set of equations capturing the heat transfer in nanostructures even in\nthe case of hetero-structures. This model only requires introducing a new\nintrinsic thermal parameter called ballistic thermal conductance and a\ngeometric one called the effective thermal conductivity. Finally, this model is\nable to reproduce accurately advanced numerical results of Monte Carlo\nsimulation for phonons in all phonon transport regime: diffusive (as the\nFourier heat transport regime is included), ballistic, and intermediate ones\neven if thermal interface are involved. This formalism should provide new\ninsights in the interpretation of experimental measurements."
    },
    {
        "anchor": "Local spin transfer torque and magnetoresistance in domain walls with\n  variable width: Use of a spin polarized current for the manipulation of magnetic domain walls\nin ferromagnetic nanowires has been the subject of intensive research for many\nyears. Recently, due to technological advancements, creating nano-contacts with\nspecial characteristics is becoming more and more prevalent. We now present a\nfull quantum investigation of the magnetoresistance and the spin transfer\ntorque in a domain wall, which is embedded in a nano-contact of Ni$_{80}$Fe$_\n{20}$, where the size of the domain wall becomes a relevant tunable parameter.\nThe dependence on the domain wall width as well as the spatial dependence of\nthe torque along the domain wall can be analyzed in complete detail. The\nmagnetoresistance drops with increasing domain wall width as expected, but also\nshows characteristic modulations and points of resonant spin-flip transmission.\nThe spin transfer torque has both significant in-plane and out-of-plane\ncontributions even without considering relaxation. A closer inspection\nidentifies contributions from the misalignment of the spin density for short\ndomain walls as well as an effective gauge field for longer domain walls, both\nof which oscillate along the domain wall.",
        "positive": "Synchronization of two anharmonic nanomechanical oscillators: We investigate the synchronization of oscillators based on anharmonic\nnanoelectromechanical resonators. Our experimental implementation allows\nunprecedented observation and control of parameters governing the dynamics of\nsynchronization. We find close quantitative agreement between experimental data\nand theory describing reactively coupled Duffing resonators with fully\nsaturated feedback gain. In the synchronized state we demonstrate a significant\nreduction in the phase noise of the oscillators, which is key for sensor and\nclock applications. Our work establishes that oscillator networks constructed\nfrom nanomechanical resonators form an ideal laboratory to study\nsynchronization given their high-quality factors, small footprint, and ease of\nco-integration with modern electronic signal processing technologies."
    },
    {
        "anchor": "Creating photon-number squeezed strong microwave fields by a Cooper-pair\n  injection laser: The use of artificial atoms as an active lasing medium opens a way to\nconstruct novel sources of nonclassical radiation. An example is the creation\nof photon-number squeezed light. Here we present a design of a laser consisting\nof multiple Cooper-pair transistors coupled to a microwave resonator. Over a\nbroad range of experimentally realizable parameters, this laser creates\nphoton-number squeezed microwave radiation, characterized by a Fano factor $F\n\\ll 1$, at a very high resonator photon number. We investigate the impact of\ngate-charge disorder in a Cooper-pair transistor and show that the system can\ncreate squeezed strong microwave fields even in the presence of maximum\ndisorder.",
        "positive": "Charge transport in pn and npn junctions of silicene: We investigate charge transport of pn and npn junctions made from silicene,\nSi analogue of graphene. The conductance shows the distinct gate-voltage\ndependences peculiar to the topological and non-topological phases, where the\ntopological phase transition is caused by external electric field. Namely, the\nconductance is suppressed in the np regime when the both sides are topological,\nwhile in the nn regime when one side is topological and the other side is\nnon-topological. Furthermore, we find that the conductance is almost quantized\nto be 0, 1 and 2. Our findings will open a new way to nanoelectronics based on\nsilicene."
    },
    {
        "anchor": "Effects of excitation frequency on high-order terahertz sideband\n  generation in semiconductors: We theoretically investigate the effects of the excitation frequency on the\nplateau of high-order terahertz sideband generation (HSG) in semiconductors\ndriven by intense terahertz (THz) fields. We find that the plateau of the\nsideband spectrum strongly depends on the detuning between the NIR laser field\nand the band gap. We use the quantum trajectory theory (three-step model) to\nunderstand the HSG. In the three-step model, an electron-hole pair is first\nexcited by a weak laser, then driven by the strong THz field, and finally\nrecombine to emit a photon with energy gain. When the laser is tuned below the\nband gap (negative detuning), the electron-hole generation is a virtual process\nthat requires quantum tunneling to occur. When the energy gained by the\nelectron-hole pair from the THz field is less than 3.2 times the ponderomotive\nenergy, the electron and the hole can be driven to the same position and\nrecombine without quantum tunneling, so the HSG will have large probability\namplitude. This leads to a plateau feature of the HSG spectrum with a\nhigh-frequency cutoff at about 3.2 times the ponderomotive energy above the\nband gap. Such a plateau feature is similar to the case of high-order harmonics\ngeneration in atoms where electrons have to overcome the binding energy to\nescape the atomic core. A particularly interesting excitation condition in HSG\nis that the laser can be tuned above the band gap (positive detuning),\ncorresponding to the unphysical \"negative\" binding energy in atoms for\nhigh-order harmonic generation. Now the electron-hole pair is generation by\nreal excitation, but the recombination process can be real or virtual depending\non the energy gained from the THz field, which determines the plateau feature\nin HSG.",
        "positive": "Hanbury Brown and Twiss Exchange Correlations in Graphene Box: Quadratic detection in linear mesoscopic transport systems produces cross\nterms that can be viewed as interference signals reflecting statistical\nproperties of charge carriers. In electronic systems these cross term\ninterferences arise from exchange effects due to Pauli principle. Here we\ndemonstrate fermionic Hanbury Brown and Twiss (HBT) exchange phenomena due to\nindistinguishability of charge carriers in a diffusive graphene system. These\nexchange effects are verified using current-current cross correlations in\ncombination with regular shot noise (autocorrelation) experiments at microwave\nfrequencies. Our results can be modeled using semiclassical analysis for a\nsquare-shaped metallic diffusive conductor, including contributions from\ncontact transparency. The experimentally determined HBT exchange factor values\nlie between the calculated ones for coherent and hot electron transport."
    },
    {
        "anchor": "Magneto-optical control of F\u00f6rster energy transfer: We introduce a general framework to study dipole-dipole energy transfer\nbetween an emitter and an absorber in a nanostructured environment. The theory\nallows us to address F\\\"orster Resonant Energy Transfer (FRET) between a donor\nand an acceptor in the presence of a nanoparticle with an anisotropic\nelectromagnetic response. In the particular case of a magneto-optical\nanisotropy, we compute the generalized FRET rate and discuss the orders of\nmagnitude. The distance dependence, the FRET efficiency and the sensitivity to\nthe orientation of the transition dipoles orientation differ from standard FRET\nand can be controlled using the static magnetic field as an external parameter.",
        "positive": "Ultrafast Carrier Recombination and Generation Rates for Plasmon\n  Emission and Absorption in Graphene: Electron-hole generation and recombination rates for plasmon emission and\nabsorption in Graphene are presented. The recombination times of carriers due\nto plasmon emission have been found to be in the tens of femtoseconds to\nhundreds of picoseconds range. The recombination times depend sensitively on\nthe carrier energy, carrier density, temperature, and the plasmon dispersion.\nCarriers near the Dirac point are found to have much longer lifetimes compared\nto carriers at higher energies. Plasmons in a Graphene layer on a polar\nsubstrate hybridize with the surface optical phonons and this hybridization\nmodifies the plasmon dispersion. We also present generation and recombination\nrates of carriers due to plasmon emission and absorption in Graphene layers on\npolar substrates."
    },
    {
        "anchor": "Memory circuit elements: from systems to applications: In this paper, we briefly review the concept of memory circuit elements,\nnamely memristors, memcapacitors and meminductors, and then discuss some\napplications by focusing mainly on the first class. We present several\nexamples, their modeling and applications ranging from analog programming to\nbiological systems. Since the phenomena associated with memory are ubiquitous\nat the nanoscale, we expect the interest in these circuit elements to increase\nin coming years.",
        "positive": "Current-Induced Instability of a Perpendicular Ferromagnet in Spin Hall\n  Geometry: We develop a theoretical formula of spin Hall torque in the presence of two\nferromagnets. While the direction of the conventional spin Hall torque always\npoints to the in-plane direction, the present system enables to manipulate the\ntorque direction acting on one magnetization by changing the direction of\nanother magnetization. Based on the diffusion equation of the spin accumulation\nand the Landauer formula, we derive analytical formula of the spin Hall torque.\nThe present model provides a solution to switch a perpendicular ferromagnet\ndeterministically at zero field using the spin Hall effect."
    },
    {
        "anchor": "Giant fluctuations and gate control of the g-factor in InAs Nanowire\n  Quantum Dots: We study the g-factor of discrete electron states in InAs nanowire based\nquantum dots. The g values are determined from the magnetic field splitting of\nthe zero bias anomaly due to the spin 1/2-Kondo effect. Unlike to previous\nstudies based on 2DEG quantum dots, the g-factors of neighboring electron\nstates show a surprisingly large fluctuation: g can scatter between 2 and 18.\nFurthermore electric gate tunability of the g-factor is demonstrated.",
        "positive": "Exploiting Aharonov-Bohm oscillations to probe Klein tunneling in\n  tunable pn-junctions in graphene: One of the unique features of graphene is that the Fermi wavelength of its\ncharge carriers can be tuned electrostatically over a wide range. This allows\nin principle to tune the transparency of a pn-junction electrostatically, as\nthis depends on the ratio between the physical extension of the junction and\nthe electron wavelength, i.e. on the effective width of the junction itself.\nHowever, this simple idea - which would allow to switch smoothly between a\nVeselago lens and a Klein-collimator - has proved to be difficult to\ndemonstrate experimentally because of the limited amount of\nindependently-tunable parameters available in most setups. In this work, we\npresent transport measurements in a quasi-ballistic Aharonov-Bohm graphene ring\nwith gate tunable pn-junctions in one arm, and show that the interference\npatterns provide unambiguous information on the Klein tunneling efficiency and\non the junctions effective width. We find a gate-controlled transparency of the\npn-junctions ranging from 35-100%. Our results are in excellent agreement with\na semiclassical description."
    },
    {
        "anchor": "Coulomb instabilities of 3D higher-order topological insulators: Topological insulator (TI) is an exciting discovery because of its robustness\nagainst disorder and interactions. Recently, higher-order TIs have been\nattracting increasing attention, because they host 1D topologically-protected\nhinge states in 3D or 0D corner states in 2D. A significantly critical issue is\nwhether the higher-order TIs also survive interactions, but it is still\nunexplored. We study the effects of weak Coulomb interaction on a 3D\nsecond-order TI, with the help of a renormalization group calculation. We find\nthat the 3D higher-order TIs are always unstable, suffering from two types of\ntopological phase transitions. One is from higher-order TI to TI, the other is\nto normal insulator (NI). The first type is accompanied by emergent\ntime-reversal and inversion symmetries and has a dynamical critical exponent\n$\\kappa=1$. The second type does not have the emergent symmetries and has\nnon-universal dynamical critical exponents $\\kappa<1$. Our results may inspire\nmore inspections on the stability of higher-order topological states of matter\nand related novel quantum criticalities.",
        "positive": "Nanoscale resolution scanning thermal microscopy with thermally\n  conductive nanowire probes: Scanning thermal microscopy (SThM) - a type of scanning probe microscopy that\nallows mapping thermal transport and temperatures in nanoscale devices, is\nbecoming a key approach that may help to resolve heat dissipation problems in\nmodern processors and develop new thermoelectric materials. Unfortunately,\nperformance of current SThM implementations in measurement of high thermal\nconductivity materials continues to me limited. The reason for these\nlimitations is two-fold - first, SThM measurements of high thermal conductivity\nmaterials need adequate high thermal conductivity of the probe apex, and\nsecondly, the quality of thermal contact between the probe and the sample\nbecomes strongly affected by the nanoscale surface corrugations of the studied\nsample. In this paper we develop analytical models of the SThM approach that\ncan tackle these complex problems - by exploring high thermal conductivity\nnanowires as a tip apex, and exploring contact resistance between the SThM\nprobe and studied surface, the latter becoming particularly important when both\ntip and surface have high thermal conductivities. We develop analytical model\nsupported by the finite element analysis simulations and by the experimental\ntests of SThM prototype using carbon nanotube (CNT) at the tip apex as a heat\nconducting nanowire. These results elucidate vital relationships between the\nperformance of the probe in SThM from one side and thermal conductivity,\ngeometry of the probe and its components from the other, providing pathway for\novercoming current limitations of SThM."
    },
    {
        "anchor": "Boundary conditions for magnetization in magnetic nano-elements: We show that the dynamic magnetization at the edges of a thin magnetic\nelement with finite lateral size can be described by new effective boundary\nconditions that take into account inhomogeneous demagnetizing fields near the\nelement edges. These fields play a dominant role in the effective pinning of\nthe dynamic magnetization at the boundaries of mesoscopic and nano-sized\nmagnetic elements. The derived effective boundary conditions generalize\nwell-known Rado-Weertman boundary conditions and are reduced to them in the\nlimiting case of a very thin magnetic element.",
        "positive": "Current-driven magnetization switching in a van der Waals ferromagnet\n  Fe3GeTe2: The recent discovery of ferromagnetism in two-dimensional (2D) van der Waals\n(vdW) materials holds promises for novel spintronic devices with exceptional\nperformances. However, in order to utilize 2D vdW magnets for building\nspintronic nanodevices such as magnetic memories, key challenges remain in\nterms of effectively switching the magnetization from one state to the other\nelectrically. Here, we devise a bilayer structure of Fe3GeTe2/Pt, in which the\nmagnetization of few-layered Fe3GeTe2 can be effectively switched by the\nspin-orbit torques (SOTs) originated from the current flowing in the Pt layer.\nThe effective magnetic fields corresponding to the SOTs are further\nquantitatively characterized using harmonic measurements. Our demonstration of\nthe SOT-driven magnetization switching in a 2D vdW magnet could pave the way\nfor implementing low-dimensional materials in the next-generation spintronic\napplications."
    },
    {
        "anchor": "Goos-H\u00e4nchen Shifts in Graphene-Based Linear Barrier: Using the energy spectrum of a system made of graphene subjected to a linear\nbarrier potential, we study the Goos-H\\\"anshen shifts. The calculation is done\nby first determining the corresponding phase shifts via the transmission and\nreflection probabilities. Numerical analysis shows that the Goos-H\\\"anshen\nshifts depend strongly on the incident energy, barrier height and width, and\nvary positively or negatively under suitable conditions.",
        "positive": "Spatial correlation of the thermally generated electromagnetic field in\n  layered media: A general formulation for the cross-spectral density tensor enabling\ncalculation of the spatial correlation of the thermally generated\nelectromagnetic field in layered media is derived. The formulation is based on\nfluctuational electrodynamics, and is thus applicable in the near and far field\nof heat sources. The resulting cross-spectral density tensor is written in\nterms of a single integration over the parallel wavevector, as the angular\nintegrations leading to numerical instability are evaluated analytically. Using\nthis formulation, the spatial correlation length in the near field of a film\nmade of silicon carbide (SiC) supporting surface phonon-polaritons (SPhPs) in\nthe infrared is analyzed. It is shown that the spatial correlation length of a\nSiC heat source suspended in vacuum decreases substantially by decreasing its\nthickness owing to SPhP coupling. In the limit of a 10-nm-thick SiC film, the\nspatial correlation length is similar to that of a blackbody. The results also\nreveal that it is possible to control the spatial coherence of a thin SiC heat\nsource via dielectric and metallic substrates, respectively allowing and\npreventing SPhP coupling. This suggests that active modulation of thermal\nemission via thin films supporting surface polaritons in the infrared is\npossible by using a phase change material substrate such as vanadium dioxide."
    },
    {
        "anchor": "Current and power spectrum in a magnetic tunnel device with an atomic\n  size spacer: Current and its noise in a ferromagnetic double tunnel barrier device with a\nsmall spacer particle were studied in the framework of the sequential tunneling\napproach. Analytical formulae were derived for electron tunneling through the\nspacer particle containing only a single energy level. It was shown that\nCoulomb interactions of electrons with a different spin orientation lead to an\nincrease of the tunnel magnetoresistance. Interactions can also be responsible\nfor the negative differential resistance. A current noise study showed, which\nrelaxation processes can enhance or reduce fluctuations leading either to a\nsuper-Poissonian or a sub-Poissonian shot noise.",
        "positive": "Acoustoelectric current in graphene due to electron deformation\n  potential and piezoelectric phonon couplings: Recent studies strongly indicate that graphene can be used as a channel\nmaterial for converting surface acoustic waves to acoustoelectric current,\nwhich is a resource for various exciting technological applications. On the\ntheoretical side, studies on phonon amplification/attenuation and\nacoustoelectric current at low temperatures in graphene have reported\napproximate analytical results under exceedingly simplifying conditions using\nthe Boltzmann transport equation. Overcoming the earlier simplifying\nassumptions, we investigate both numerically and analytically the governing\nkinetic equations for amplification/attenuation and acoustoelectric current,\ntaking into account the piezoelectric and deformation potential electron phonon\ncoupling mechanism in the semi classical Boltzmann transport formalism\napproach, and obtain analytical results that are in reasonable agreement with\nthe reported experimental results."
    },
    {
        "anchor": "Observation of plasmon-phonon coupling in natural 2D graphene-talc\n  heterostructures: Two-dimensional (2D) materials occupy noteworthy place in nanophotonics\nproviding for subwavelength light confinement and optical phenomena dissimilar\nto those of their bulk counterparts. In the mid-infrared, graphene-based\nheterostructures and van der Waals crystals of hexagonal boron nitride (hBN)\noverwhelmingly concentrate the attention by exhibiting real-space nano-optics\nfrom plasmons, phonon-polaritons and hybrid plasmon phonon-polaritons\nquasiparticles. Here we present the mid-infrared nanophotonics of talc, a\nnatural atomically flat layered material, and graphene-talc (G-talc)\nheterostructures using broadband synchrotron infrared nano-spectroscopy. We\nachieve wavelength tuning of the talc resonances, assigned to in- and\nout-of-plane vibrations by changing the thickness of the crystals, which serves\nas its infrared fingerprints. Moreover, we encounter coupling of the graphene\nplasmons polaritons with surface optical phonons of talc. As in the case of the\nG-hBN heterostructures, this coupling configures hybrid surface plasmon\nphonon-polariton modes causing 30 % increase in intensity for the out-of-plane\nmode, blue-shift for the in-plane mode and we have succeeded in altering the\namplitude of such hybridization by varying the gate voltage. Therefore, our\nresults promote talc and G-talc heterostructures as appealing materials for\nnanophotonics, like hBN and G-hBN, with potential applications for controllably\nmanipulating infrared electromagnetic radiation at the subdiffraction scale.",
        "positive": "Flat Energy Bands within Antiphase and Twin Boundaries and at Open Edges\n  in Topological Materials: A model for two-dimensional electronic, photonic, and mechanical metamaterial\nsystems is presented, which has flat one-dimensional zero-mode energy bands and\nstable localized states of a topological origin confined within twin\nboundaries, antiphase boundaries, and at open edges. Topological origins of\nthese flat bands are analyzed for an electronic system as a specific example,\nusing a two-dimensional extension of the Su-Schrieffer-Heeger Hamiltonian with\nalternating shift of the chains. It is demonstrated that the slow group\nvelocities of the localized flat band states are sensitively controlled by the\ndistance between the boundaries and the propagation can be guided through\ndesigned paths of these boundaries. We also discuss how to realize this model\nin metamaterials."
    },
    {
        "anchor": "Strong enhancement of photoresponsivity with shrinking the electrodes\n  spacing in few layer GaSe photodetectors: A critical challenge for the integration of the optoelectronics is that\nphotodetectors have relatively poor sensitivities at the nanometer scale. It is\ngenerally believed that a large electrodes spacing in photodetectors is\nrequired to absorb sufficient light to maintain high photoresponsivity and\nreduce the dark current. However, this will limit the optoelectronic\nintegration density. Through spatially resolved photocurrent investigation, we\nfind that the photocurrent in metal-semiconductor-metal (MSM) photodetectors\nbased on layered GaSe is mainly generated from the photoexcited carriers close\nto the metal-GaSe interface and the photocurrent active region is always close\nto the Schottky barrier with higher electrical potential. The photoresponsivity\nmonotonically increases with shrinking the spacing distance before the direct\ntunneling happen, which was significantly enhanced up to 5,000 AW-1 for the\nbottom contacted device at bias voltage 8 V and wavelength of 410 nm. It is\nmore than 1,700-fold improvement over the previously reported results. Besides\nthe systematically experimental investigation of the dependence of the\nphotoresponsivity on the spacing distance for both the bottom and top contacted\nMSM photodetectors, a theoretical model has also been developed to well explain\nthe photoresponsivity for these two types of device configurations. Our\nfindings realize shrinking the spacing distance and improving the performance\nof 2D semiconductor based MSM photodetectors simultaneously, which could pave\nthe way for future high density integration of 2D semiconductor optoelectronics\nwith high performances.",
        "positive": "Anomalous magneto-transport in disordered structures: classical\n  edge-state percolation: By event-driven molecular dynamics simulations we investigate\nmagneto-transport in a two-dimensional model with randomly distributed\nscatterers close to the field-induced localization transition. This transition\nis generated by percolating skipping orbits along the edges of obstacle\nclusters. The dynamic exponents differ significantly from those of the\nconventional transport problem on percolating systems, thus establishing a new\ndynamic universality class. This difference is tentatively attributed to a\nweak-link scenario, which emerges naturally due to barely overlapping edge\ntrajectories. We make predictions for the frequency-dependent conductivity and\ndiscuss implications for active colloidal circle swimmers in a heterogeneous\nenvironment."
    },
    {
        "anchor": "Tailoring the band structure of twisted double bilayer graphene with\n  pressure: Twisted two-dimensional structures open new possibilities in band structure\nengineering. At magic twist angles, flat bands emerge, which give a new drive\nto the field of strongly correlated physics. In twisted double bilayer graphene\ndual gating allows changing the Fermi level and hence the electron density and\nalso allows tuning the interlayer potential, giving further control over band\ngaps. Here, we demonstrate that by applying hydrostatic pressure, an additional\ncontrol of the band structure becomes possible due to the change of tunnel\ncouplings between the layers. We find that the flat bands and the gaps\nseparating them can be drastically changed by pressures up to 2 GPa, in good\nagreement with our theoretical simulations. Furthermore, our measurements\nsuggest that in finite magnetic field due to pressure a topologically\nnon-trivial band gap opens at the charge neutrality point at zero displacement\nfield.",
        "positive": "Suppression of dephasing and phase lapses in the fractional quantum Hall\n  regime: A charge fluctuator which is electrostatically coupled to a conducting\nchannel may fully dephase quantum transport through the latter. Here, we\naddress the case where a quantum dot (QD), playing the role of a charge\nfluctuator, is tunnel-coupled to an additional channel. In the case where the\nlatter may support fractional charge, distinct differences from the integer\ncase arise: Abrupt phase lapses of the transmission through the conducting\nchannel occur (which may or may not be equal to $\\pi$). This is accompanied by\na cusp-like suppression of the interferometer's visibility, yet no full\ndephasing. We interpret our findings in terms of the entanglement between the\nfluctuator and the conducting channels."
    },
    {
        "anchor": "Polariton condensates at room temperature: We review the recent developments of the polariton physics in microcavities\nfeaturing the exciton-photon strong coupling at room-temperature, and leading\nto the achievement of room-temperature polariton condensates. Such cavities\nembed active layers with robust excitons that present a large binding energy\nand a large oscillator strength, i.e. wide bandgap inorganic or organic\nsemiconductors, or organic molecules. These various systems are compared, in\nterms of figures of merit and of common features related to their strong\noscillator strength. The various demonstrations of polariton laser are\ncompared, as well as their condensation phase diagrams. The room-temperature\noperation indeed allows a detailed investigation of the thermodynamic and\nout-of-equilibrium regimes of the condensation process. The crucial role of the\nspatial dynamics of the condensate formation is discussed, as well as the\ndebated issue of the mechanism of stimulated relaxation from the reservoir to\nthe condensate under non-resonant excitation. Finally the prospects of\npolariton devices are presented.",
        "positive": "Proximity effect-assisted absorption of spin currents in superconductors: The injection of pure spin current into superconductors by the dynamics of a\nferromagnetic contact is studied theoretically. Taking into account suppression\nof the order parameter at the interfaces (inverse proximity effect) and the\nenergy-dependence of spin-flip scattering, we determine the\ntemperature-dependent ferromagnetic resonance linewidth broadening. Our results\nagree with recent experiments in Nb|permalloy bilayers [C. Bell et al.,\narXiv:cond-mat/0702461]."
    },
    {
        "anchor": "In-plane optical phonon modes of current-carrying graphene: In this work, we study the in-plane optical phonon modes of current-carrying\nsingle-layer graphene whose coupling to the $\\pi$ electron gas is strong. Such\nmodes are expected to undergo a frequency shift compared to the\nnon-current-carrying state due to the non-equilibrium occupation of the Dirac\ncone electronic eigen-states with the flowing $\\pi$ electron gas. Large\nelectron-phonon coupling (EPC) can be identified by an abrupt change in the\nslope of the phonon mode dispersion known as the Kohn anomaly, which mainly\noccurs for (i) the in-plane longitudinal/transverse optical (LO/TO) modes at\nthe Brillouin zone (BZ) center ($\\Gamma$ point), and (ii) the TO modes at the\nBZ corners ($K$ points). We show that the breaking of the rotational symmetry\nby the DC current results in different frequency shifts to the $\\Gamma$-TO and\n$\\Gamma$-LO modes. More specifically, the DC current breaks the TO-LO mode\ndegeneracy at the $\\Gamma$ point which ideally would be manifested as the\nsplitting of the Raman G peak.",
        "positive": "Non-local detection of resistance fluctuations of an open quantum dot: We investigate quantum fluctuations in the non-local resistance of an open\nquantum dot which is connected to four reservoirs via quantum point contacts.\nIn this four-terminal quantum dot the voltage path can be separated from the\ncurrent path. We measured non-local resistance fluctuations of several hundreds\nof Ohms, which have been characterized as a function of bias voltage, gate\nvoltage and perpendicular magnetic field. The amplitude of the resistance\nfluctuations is strongly reduced when the coupling between the voltage probes\nand the dot is enhanced. Along with experimental results, we present a\ntheoretical analysis based on the Landauer-B\\\"{u}ttiker formalism. While the\ntheory predicts non-local resistance fluctuations of considerably larger\namplitude than what has been observed, agreement with theory is very good if an\nadditional dephasing mechanism is assumed."
    },
    {
        "anchor": "Theory of inverse Rashba-Edelstein effect induced by spin pumping into a\n  two-dimensional electron gas: The inverse Rashba-Edelstein effect (IREE) in a two-dimensional electron gas\n(2DEG) induced by spin pumping from an adjacent ferromagnetic insulator (FI) is\ninvestigated theoretically. In particular, spin and current densities in the\n2DEG in which both Rashba and Dresselhaus spin-orbit interactions coexist are\nformulated, and their dependencies on ferromagnetic resonance frequency and\norientation of the spin in the FI are clarified. It is shown that spin density\ndiverges when the ratio between the Rashba and Dresselhaus spin-orbit\ninteractions approaches unity, while current density stays finite there. These\nresults can be applied for evaluating spin splitting on the Fermi surface in a\n2DEG and designing spintronic devices using IREE.",
        "positive": "Effect of TE-TM Splitting on the topological stability of half-vortices\n  in exciton-polariton condensates: Half-vortices have been recently shown to be the elementary topological\ndefects supported by a spinor cavity exciton-polaritons condensates with spin\nanisotropic interactions (Y. G. Rubo, Phys. Rev. Lett. 99, 106401 (2007)). A\nhalf vortex is composed by an integer vortex for one circular component of the\ncondensate, whereas the other component remain static. We analyze theoretically\nthe effect of the splitting between TE and TM polarized eigen modes on the\nstructure of the vortices in this system. For TE and TM modes, the polarization\nstates depend on the direction of propagations of particles and imposes some\nwell defined phase relation between the two circular component. As a result\nelementary topogical defects in this system are no more half vortices but\ninteger vortices correspond to an integer vortex for both circular components\nof the condensate. The intrinsic life time of half vortices is given and the\ntexture of a few vortex states is analyzed."
    },
    {
        "anchor": "Virtual Scanning Tunneling Microscopy: A Local Spectroscopic Probe of 2D\n  Electron Systems: We propose a novel probe technique capable of performing local\nlow-temperature spectroscopy on a 2D electron system (2DES) in a semiconductor\nheterostructure. Motivated by predicted spatially-structured electron phases,\nthe probe uses a charged metal tip to induce electrons to tunnel locally,\ndirectly below the tip, from a \"probe\" 2DES to a \"subject\" 2DES of interest. We\ntest this concept with large-area (non-scanning) tunneling measurements, and\npredict a high spatial resolution and spectroscopic capability, with minimal\ninfluence on the physics in the subject 2DES.",
        "positive": "Electrical manipulation of the edge states in graphene and the effect on\n  the quantum Hall transport: We investigate new properties of the Dirac electrons in the finite graphene\nsample under perpendicular magnetic field that emerge when an in-plane electric\nbias is also applied. The numerical analysis of the Hofstadter spectrum and of\nthe edge-type wave functions evidentiate the presence of shortcut edge states\nthat appear under the influence of the electric field. The states are\ncharacterized by a specific spatial distribution, which follows only partially\nthe perimeter, and exhibit ridges that shortcut opposite sides of the graphene\nplaquette. Two kinds of such states have been found in different regions of the\nspectrum, their particular spatial localization being shown along with the\ndiamagnetic moments that reveal their chirality. By simulating a four-lead Hall\ndevice, we investigate the transport properties and observe new, unconventional\nplateaus of the integer quantum Hall effect, which are associated with the\npresence of the shortcut edge states. The contributions of the novel states to\nthe transmittance matrix that determine the new transport properties are shown.\nThe shortcut edge states resulting from the splitting of the n=0 Landau level\nrepresent a special case, giving rise to non-trivial transverse and\nlongitudinal resistance."
    },
    {
        "anchor": "Splitting of interlayer shear modes and photon energy dependent\n  anisotropic Raman response in $N$-layer ReSe$_2$ and ReS$_2$: We investigate the interlayer phonon modes in $N$-layer rhenium diselenide\n(ReSe$_2$) and rhenium disulfide (ReS$_2$) by means of ultralow-frequency\nmicro-Raman spectroscopy. These transition metal dichalcogenides exhibit a\nstable distorted octahedral (1T') phase with significant in-plane anisotropy,\nleading to sizable splitting of the (in-plane) layer shear modes. The\nfan-diagrams associated with the measured frequencies of the interlayer shear\nmodes and the (out-of-plane) interlayer breathing modes are perfectly described\nby a finite linear chain model and allow the determination of the interlayer\nforce constants. Nearly identical values are found for ReSe$_2$ and ReS$_2$.\nThe latter are appreciably smaller than but on the same order of magnitude as\nthe interlayer force constants reported in graphite and in trigonal prismatic\n(2Hc) transition metal dichalcogenides (such as MoS$_2$, MoSe$_2$, MoTe$_2$,\nWS$_2$, WSe$_2$), demonstrating the importance of van der Waals interactions in\n$N$-layer ReSe$_2$ and ReS$_2$. In-plane anisotropy results in a complex\nangular dependence of the intensity of all Raman modes, which can be\nempirically utilized to determine the crystal orientation. However, we also\ndemonstrate that the angular dependence of the Raman response drastically\ndepends on the incoming photon energy, shedding light on the importance of\nresonant exciton-phonon coupling in ReSe$_2$ and ReS$_2$.",
        "positive": "Trapping electrons in semiconductor air bubbles: A theoretical approach: The role of image charges in nanoporous semiconductor materials is\ninvestigated within the framework of the effective mass and envelope function\napproximations. We show that nanometric air bubbles in these materials can act\nas electron-trapping centers. This trapping capability originates from a deep\nstabilizing self-polarization potential well induced by the air - semiconductor\ndielectric mismatch which can surpass the electroaffinity barrier. The trapping\nstrength is a function of the pore size and the bulk parameters of the matrix\nmaterial. A {\\it trapping parameter} characteristic for each semiconductor\nmaterial is defined. This parameter provides a simple way to ascertain the\nmaximum pore size in a given material which is able to induce self-trapping of\nexcess electrons."
    },
    {
        "anchor": "Ultrafast field control of symmetry, reciprocity, and reversibility in\n  buckled graphene-like materials: We theoretically show that buckled two-dimensional graphene-like materials\n(silicene and germanene) subjected to a femtosecond strong optical pulse can be\ncontrolled by the optical field component normal to their plane. In such strong\nfields, these materials are predicted to exhibit non-reciprocal reflection,\noptical rectification and generation of electric currents both parallel and\nnormal to the in-plane field direction. Reversibility of the conduction band\npopulation is also field- and carrier-envelope phase controllable. There is a\nnet charge transfer along the material plane that is also dependent on the\nnormal field component. Thus a graphene-like buckled material behaves\nanalogously to a field-effect transistor controlled and driven by the electric\nfield of light with subcycle (femtosecond) speed.",
        "positive": "Evolution of the nu = 1 Ground-State in Coupled Double Quantum Wells:\n  Optical Evidence for Broken-Symmetry States: We present the first magneto-absorption studies of coupled electron double\nlayers in the quantum Hall regime. Optical absorption spectra in the vicinity\nof total filling factor nu = 1 reveal intriguing behavior that have no analog\nin the single electron layer nu = 1 state and demonstrate the interplay between\nsingle-particle tunneling and inter-layer Coulomb effects. The spectra provide\ndirect evidence of a ground-state that evolves from a region dominated by\nsingle-particle tunneling to a regime in which inter-layer Coulomb interactions\ndetermine the nature of the ground-state. Moreover the spectra provide the\nfirst direct evidence that the incompressible ground-state at nu = 1 in the\nmany-body regime is not fully pseudospin polarized and is sensitive to the\neffects of quantum fluctuations in the pseudospin variable."
    },
    {
        "anchor": "Statistical analysis of the transmission based on the DMPK equation: An\n  application to Pb nano-contacts: The density of the transmission eigenvalues of Pb nano-contacts has been\nestimated recently in mechanically controllable break-junction experiments.\nMotivated by these experimental analyses, here we study the evolution of the\ndensity of the transmission eigenvalues with the disorder strength and the\nnumber of channels supported by the ballistic constriction of a quantum point\ncontact in the framework of the Dorokhov-Mello-Pereyra-Kumar equation. We find\nthat the transmission density evolves rapidly into the density in the diffusive\nmetallic regime as the number of channels $N_c$ of the constriction increase.\nTherefore, the transmission density distribution for a few $N_c$ channels comes\nclose to the known bimodal density distribution in the metallic limit. This is\nin agreement with the experimental statistical-studies in Pb nano-contacts. For\nthe two analyzed cases, we show that the experimental densities are seen to be\nwell described by the corresponding theoretical results.",
        "positive": "Dynamical Spin-Orbit-Based Spin Transistor: Spin-orbit interaction (SOI) has been a key tool to steer and manipulate\nspin-dependent transport properties in two-dimensional electron gases. Here we\ndemonstrate how spin currents can be created and efficiently read out in nano-\nor mesoscale conductors with time-dependent and spatially inhomogeneous Rashba\nSOI. Invoking an underlying non-Abelian SU(2) gauge structure we show how\ntime-periodic spin-orbit fields give rise to spin electric forces and enable\nthe generation of pure spin currents of the order of several hundred\nnano-Amperes. In a complementary way, by combining gauge transformations with\n\"hidden\" Onsager relations, we exploit spatially inhomogeneous Rashba SOI to\nconvert spin currents (back) into charge currents. In combining both concepts,\nwe devise a spin transistor that integrates efficient spin current generation,\nby employing dynamical SOI, with its experimentally feasible detection via\nconversion into charge signals. We derive general expressions for the\nrespective spin- and charge conductance, covering large parameter regimes of\nSOI strength and driving frequencies, far beyond usual adiabatic approaches\nsuch as the frozen scattering matrix approximation. We check our analytical\nexpressions and approximations with full numerical spin-dependent transport\nsimulations and demonstrate that the predictions hold true in a wide range from\nlow to high driving frequencies."
    },
    {
        "anchor": "Non-linear response of molecular junctions: The polaron model revisited: A polaron model proposed as a possible mechanism for nonlinear conductance\n[Galperin M, Ratner M A, and Nitzan A 2005 Nano Lett. 5 125-30] is revisited\nwith focus on the differences between the weak and strong molecule-lead\ncoupling cases. Within the one-molecular level model we present an approximate\nexpression for the electronic Green function corresponding to inelastic\ntransport case, which in the appropriate limits reduces to expressions\npresented previously for the isolated molecule and for molecular junction\ncoupled to a slow vibration (static limit). The relevance of considerations\nbased on the isolated molecule limit to understanding properties of molecular\njunctions is discussed.",
        "positive": "Geometric approach to fragile topology beyond symmetry indicators: We present a framework to systematically address topological phases when\nfiner partitionings of bands are taken into account, rather than only\nconsidering the two subspaces spanned by valence and conduction bands. Focusing\non $C_2\\mathcal{T}$-symmetric systems that have gained recent attention, for\nexample in the context of layered van-der-Waals graphene heterostructures, we\nrelate these insights to homotopy groups of Grassmannians and flag varieties,\nwhich in turn correspond to cohomology classes and Wilson-flow approaches. We\nfurthermore make use of a geometric construction, the so-called Pl\\\"ucker\nembedding, to induce windings in the band structure necessary to facilitate\nnon-trivial topology. Specifically, this directly relates to the\nparametrization of the Grassmannian, which describes partitioning of an\narbitrary band structure and is embedded in a better manageable exterior\nproduct space. From a physical perspective, our construction encapsulates and\nelucidates the concepts of fragile topological phases beyond symmetry\nindicators as well as non-Abelian reciprocal braiding of band nodes that arises\nwhen the multiple gaps are taken into account. The adopted geometric viewpoint\nmost importantly culminates in a direct and easily implementable method to\nconstruct model Hamiltonians to study such phases, constituting a versatile\ntheoretical tool."
    },
    {
        "anchor": "Electromagnetic field induced suppression of transport through $n$-$p$\n  junctions in graphene: We study quasi-particle transmission through an $n $-$p$ junction in a\ngraphene irradiated by an electromagnetic field (EF). In the absence of EF the\nelectronic spectrum of undoped graphene is gapless, and one may expect the\nperfect transmission of quasi-particles flowing perpendicular to the junction.\nWe demonstrate that the resonant interaction of propagating quasi-particles\nwith the component of EF parallel to the junction induces a\n\\textit{non-equilibrium dynamic gap} $(2\\Delta_R)$ between electron and hole\nbands in the quasi-particle spectrum of graphene. In this case the strongly\nsuppressed quasi-particle transmission is only possible due to interband\ntunnelling. The effect may be used for controlling transport properties of\ndiverse structures in graphene, like, e.g., $n$-$p$-$n$ transistors, single\nelectron transistors, quantum dots, etc., by variation of the intensity $S$ and\nfrequency $\\omega$ of the external radiation.",
        "positive": "Fractional Quantum Hall States on CP2 Space: We study four-dimensional fractional quantum Hall states on CP2 geometry from\nmicroscopic approaches. While in 2d the standard Laughlin wave function, given\nby a power of Vandermonde determinant, admits a product representation in terms\nof the Jastrow factor, this is no longer true in higher dimensions. In 4d we\ncan define two different types of Laughlin wavefunctions, the\nDeterminant-Laughlin (Det-Laughlin) and Jastrow-Laughlin (Jas-Laughlin) states.\nWe find that they are exactly annihilated by, respectively, two-particle and\nthree-particle short ranged interacting Hamiltonians. We then mainly focus on\nthe ground state, low energy excitations and the quasi-hole degeneracy of\nDet-Laughlin state. The quasi-hole degeneracy exhibits an anomalous counting,\nindicating the existence of multiple forms of quasi-hole wavefunctions. We\nargue that these are captured by the mathematical framework of the \"commutative\nalgebra of N-points in the plane\". We also generalize the pseudopotential\nformalism to dimensions higher than two, by considering coherent state\nwavefunction of bound states. The microscopic wavefunctions and Hamiltonians\nstudied in this work pave the way for systematic study of high dimensional\ntopological phase of matter that is potentially realizable in cold atom and\noptical experiments."
    },
    {
        "anchor": "Knotted Non-Hermitian Metals: We report on the occurrence of knotted metallic band structures as stable\ntopological phases in non-Hermitian (NH) systems. These knotted NH metals are\ncharacterized by open Fermi surfaces, known in mathematics as Seifert surfaces,\nthat are bounded by knotted lines of exceptional points. Quite remarkably, and\nin contrast to the situation in Hermitian systems, no fine tuning or symmetries\nare required in order to stabilize these exotic phases of matter. By explicit\nconstruction, we derive microscopic tight-binding models hosting knotted NH\nmetals with strictly short-ranged hopping, and investigate the stability of\ntheir topological properties against perturbations. Building up on recently\ndeveloped experimental techniques for the realization of NH band structures, we\ndiscuss how the proposed models may be experimentally implemented in photonic\nsystems.",
        "positive": "Exceptionally strong coupling of defect emission in hexagonal boron\n  nitride to stacking sequences: Van der Waals structures present a unique opportunity for tailoring material\ninterfaces and integrating photonic functionalities. By precisely manipulating\nthe twist angle and stacking sequences, it is possible to elegantly tune and\nfunctionalize the electronic and optical properties of layered van der Waals\nstructures. Among these materials, two-dimensional hexagonal boron nitride\n(hBN) stands out for its remarkable optical properties and wide band gap,\nmaking it a promising host for solid state single photon emitters at room\ntemperature. Previous investigations have demonstrated the observation of\nbright single photon emission in hBN across a wide range of wavelengths. In\nthis study, we unveil an application of van der Waals technology in modulating\ntheir spectral shapes and brightness by carefully controlling the stacking\nsequences and polytypes. Our theoretical analysis reveals remarkably large\nvariations in the Huang-Rhys factors-an indicator of the interaction between a\ndefect and its surrounding lattice-reaching up to a factor of 3.3 for the same\ndefect in different stackings. We provide insights into the underlying\nmechanism behind these variations, shedding light on the design principles\nnecessary to achieve rational and precise control of defect emission. This work\npaves the way for enhancing defect identification and facilitating the\nengineering of highly efficient single photon sources and qubits using van der\nWaals materials."
    },
    {
        "anchor": "Electrical low-frequency $1/f^\u03b3$ noise due to surface diffusion\n  of scatterers on an ultra low noise graphene platform: Low-frequency $1/f^{\\gamma}$ noise is ubiquitous, even in high-end electronic\ndevices. For qubits such noise results in decrease of their coherence times.\nRecently, it was found that adsorbed O$_2$ molecules provide the dominant\ncontribution to flux noise in superconducting quantum interference devices. To\nclarify the basic principles of such adsorbant noise, we have investigated the\nformation of low-frequency noise while the mobility of surface adsorbants is\nvaried by temperature. In our experiments, we measured low-frequency current\nnoise in suspended monolayer graphene samples under the influence of adsorbed\nNe atoms. Owing to the extremely small intrinsic noise of graphene in suspended\nCorbino geometry, we could resolve a combination of $1/f^{\\gamma}$ and\nLorentzian noise spectra induced by the presence of Ne. We find that the\n$1/f^{\\gamma}$ noise is caused by surface diffusion of Ne atoms and by\ntemporary formation of few-Ne-atom clusters. Our results support the idea that\nclustering dynamics of defects is relevant for understanding of $1/f$ noise in\ngeneral metallic systems.",
        "positive": "Zero energy and chiral edge modes in a p-wave magnetic spin model: In this work we discuss the formation of zero energy vortex and chiral edge\nmodes in a fermionic representation of the Kitaev honeycomb model. We introduce\nthe representation and show how the associated Jordan-Wigner procedure\nnaturally defines the so called branch cuts that connect the topological vortex\nexcitations. Using this notion of the branch cuts we show how to, in the\nnon-Abelian phase of the model, describe the Majorana zero mode structure\nassociated with vortex excitations. Furthermore we show how, by intersecting\nthe edges between Abelian and non-Abelian domains, the branch cuts dictate the\ncharacter of the chiral edge modes. In particular we will see in what\nsituations the exact zero energy Majorana edge modes exist. On a cylinder, and\nfor the particular instances where the Abelian phase of the model is the full\nvacuum, we have been able to exactly solve for the systems edge energy\neigensolutions and derive a recursive formula that exactly describes the edge\nmode structure. Penetration depth is also calculated and shown to be dependent\non the momentum of the edge mode. These solutions also describe the overall\ncharacter of the fully open non-Abelian domain and are excellent approximations\nat moderate distances from the corners."
    },
    {
        "anchor": "Effect of Zeeman splitting on magnetoresistivity of 2D hole gas in a\n  Ge_{1-x}Si_x/Ge/Ge_{1-x}Si_x quantum well: For a two-dimensional (2D) hole system (confined within Ge layers of a\nmultilayered p-Ge/Ge_{1-x}Si_x heterostructure) described by Luttinger\nHamiltonian with the g-factor highly anisotropic for orientations of magnetic\nfield perpendicular and parallel to the 2D plane (g_perp >> g_par), reported is\nan observation of low-temperature transition from metallic (dR/dT > 0) to\ninsulator (dR/dT < 0) behavior of resistivity R(T) induced by a perpendicular\nmagnetic field B. The revealed positive magnetoresistance scales as a function\nof B/T. We attribute this finding to a suppression of the triplet channel of\nelectron-electron (hole-hole) interaction due to Zeeman splitting in the hole\nspectrum.",
        "positive": "Polaritonic hybrid-epsilon-near-zero modes: engineering strong\n  optoelectronic coupling and dispersion in doped cadmium oxide bilayers: Polaritonic materials that support epsilon-near-zero (ENZ) modes offer the\nopportunity to design light-matter interactions at the nanoscale through\nphenomena like resonant perfect absorption and extreme sub-wavelength light\nconcentration. To date, the utility of ENZ modes is limited in propagating\npolaritonic systems by a relatively flat spectral dispersion, which gives ENZ\nmodes small group velocities and short propagation lengths. Here we overcome\nthis constraint by coupling ENZ modes to surface plasmon polariton (SPP) modes\nin doped cadmium oxide ENZ-on-SPP bilayers. What results is a strongly coupled\nhybrid mode, characterized by strong anti-crossing and a large spectral\nsplitting on the order of 1/3 of the mode frequency. The resonant frequencies,\ndispersion, and coupling of these polaritonic-hybrid-epsilon-near-zero (PH-ENZ)\nmodes are controlled by tailoring the modal oscillator strength and the ENZ-SPP\nspectral overlap, which can potentially be utilized for actively tunable strong\ncoupling at the nanoscale. PH-ENZ modes ultimately leverage the most desirable\ncharacteristics of both ENZ and SPP modes through simultaneous strong interior\nfield confinement and mode propagation."
    },
    {
        "anchor": "Semimetal behavior of bilayer stanene: Stanene is a two-dimensional (2D) buckled honeycomb structure which has been\nstudied recently owing to its promising electronic properties for potential\nelectronic and spintronic applications in nanodevices. In this article, we\npresent a first-principles study of electronic properties of fluorinated\nbilayer stanene. The effect of tensile strain, intrinsic spin-orbit, and van\nder Waals interactions are considered within the framework of density\nfunctional theory. The electronic band structure shows a very small overlap\nbetween valence and conduction bands at the {\\Gamma} point which is a\ncharacteristic of semimetal in fluorinated bilayer stanene. A relatively high\nvalue of tensile strain is needed to open an energy band gap in the electronic\nband structure and the parity analysis reveals that the strained nanostructure\nis a trivial insulator. According to our results, despite the monolayer\nfluorinated stanene, the bilayer one is not an appropriate candidate for\ntopological insulator.",
        "positive": "Edge magnetotransport in graphene: A combined analytical and numerical\n  study: The current flow along the boundary of graphene stripes in a perpendicular\nmagnetic field is studied theoretically by the nonequilibrium Green's function\nmethod. In the case of specular reflections at the boundary, the Hall\nresistance shows equidistant peaks, which are due to classical cyclotron\nmotion. When the strength of the magnetic field is increased, anomalous\nresistance oscillations are observed, similar to those found in a\nnonrelativistic 2D electron gas [New. J. Phys. 15:113047 (2013)]. Using a\nsimplified model, which allows to solve the Dirac equation analytically, the\noscillations are explained by the interference between the occupied edge states\ncausing beatings in the Hall resistance. A rule of thumb is given for the\nexperimental observability. Furthermore, the local current flow in graphene is\naffected significantly by the boundary geometry. A finite edge current flows on\narmchair edges, while the current on zigzag edges vanishes completely. The\nquantum Hall staircase can be observed in the case of diffusive boundary\nscattering. The number of spatially separated edge channels in the local\ncurrent equals the number of occupied Landau levels. The edge channels in the\nlocal density of states are smeared out but can be made visible if only a\nsubset of the carbon atoms is taken into account."
    },
    {
        "anchor": "Vibrational Properties of a Naturally Occurring Semiconducting van der\n  Waals heterostructure: We present vibrational properties of Franckeite, which is a naturally\noccurring van der Waals heterostructure consisting of two different\nsemiconducting layers. Franckeite is a complex layered crystal composed of\nalternating SnS$_2$ like pseudohexagonal and PbS-like pseudotetragonal layers\nstacked on top of each other, providing a unique platform to study vibrational\nproperties and thermal transport across layers with mass density and phonon\nmismatches. By using micro-Raman spectroscopy and first-principles Raman\nsimulations, we found that the PbS-like pseudotetragonal structure is mostly\ncomposed of Pb$_3$SbS$_4$. We also discovered several low-frequency Raman modes\nthat originate from the intralayer vibrations of the pseudotetragonal layer.\nUsing density functional theory, we determined all vibrational patterns of\nFranckeite, whose signatures are observed in the Raman spectrum. By studying\ntemperature dependent Raman spectroscopy (300 K - 500 K), we have found\ndifferent temperature coefficients for both pseudotetragonal and\npseudohexagonal layers. We believe that our study will help understand the\nvibration modes of its complex heterostructure and the thermal properties at\nthe nanoscale.",
        "positive": "Pure spin photocurrents: The pure spin currents, i.e., the counterflow of particles with opposite spin\norientations, can be optically injected in semiconductors. Here, we develop a\nphenomenological theory, which describes the polarization dependencies of spin\ncurrents excited by linearly polarized light in bulk semiconductors and quantum\nwell structures of various symmetries. We present microscopic descriptions of\nthe pure spin photocurrents for interband optical transitions in undoped\nquantum wells as well as for direct intersubband and indirect intrasubband\n(Drude-like) transitions in n-doped quantum well structures. We also\ndemonstrate that pure spin currents can be generated in structures of\nsufficiently low symmetries by simple electron gas heating. The theoretical\nresults are compared with recent experimental observations."
    },
    {
        "anchor": "Spin superfluid Josephson oscillator: The magnetic analogue of the Josephson effect can be exploited to develop a\nnew class of nano-spin oscillators that we denote as spin superfluid Josephson\noscillators. Such a device, consisting of two exchange coupled easy-plane\nmetallic ferromagnets separated by a thin normal metal spacer, is proposed and\nanalyzed. A spin chemical potential difference drives a $2\\pi$ precession of\nthe in-plane magnetization of each ferromagnet. The $2 \\pi$ precession angle\ngives maximum values of the giant magnetoresistance, resulting in large output\npower compared to conventional spin Hall oscillators. An applied ac current\nresults in a time-averaged magnetoresistance with Shapiro-like steps. The\nmultistate mode-locking behavior exhibited by the spin Shapiro steps may be\nexplored for applications in neuromorphic computing. As an experimental\ncharacterization method, electrical measurements of spin superfluid Josephson\njunctions can provide additional signatures of spin superfluidity.",
        "positive": "Scanned Potential Microscopy of Edge and Bulk Currents in the Quantum\n  Hall Regime: Using an atomic force microscope as a local voltmeter, we measure the Hall\nvoltage profile in a 2D electron gas in the quantum Hall (QH) regime. We\nobserve a linear profile in the bulk of the sample in the transition regions\nbetween QH plateaus and a distinctly nonlinear profile on the plateaus. In\naddition, localized voltage drops are observed at the sample edges in the\ntransition regions. We interpret these results in terms of theories of edge and\nbulk currents in the QH regime."
    },
    {
        "anchor": "Spin-orbit induced longitudinal spin-polarized currents in non-magnetic\n  solids: For certain non-magnetic solids with low symmetry the occurrence of\nspin-polarized longitudinal currents is predicted. These arise due to an\ninterplay of spin-orbit interaction and the particular crystal symmetry. This\nresult is derived using a group-theoretical scheme that allows investigating\nthe symmetry properties of any linear response tensor relevant to the field of\nspintronics. For the spin conductivity tensor it is shown that only the\nmagnetic Laue group has to be considered in this context. Within the introduced\ngeneral scheme also the spin Hall- and additional related transverse effects\nemerge without making reference to the two-current model. Numerical studies\nconfirm these findings and demonstrate for (Au$_{1-x}$Pt$_{\\rm x}$)$_4$Sc that\nthe longitudinal spin conductivity may be in the same order of magnitude as the\nconventional transverse one. The presented formalism only relies on the\nmagnetic space group and therefore is universally applicable to any type of\nmagnetic order.",
        "positive": "Band Tunneling through Double Barrier in Bilayer Graphene: By taking into account the full four band energy spectrum, we calculate the\ntransmission probability and conductance of electrons across symmetric and\nasymmetric double potential barrier with a confined interlayer potential\ndifference in bilayer graphene. For energies less than the interlayer coupling\n\\gamma_{1}, E<\\gamma_1, we have one channel for transmission which exhibits\nresonances, even for incident particles with energies less than the strength of\nbarriers, E < U_j, depending on the double barrier geometry. In contrast, for\nhigher energies E > \\gamma_{1}, we obtain four possible ways for transmission\nresulting from the two propagating modes. We compute the associated\ntransmission probabilities as well as their contribution to the conductance,\nstudy the effect of the double barrier geometry."
    },
    {
        "anchor": "Unified description of bulk and interface-enhanced spin pumping: The dynamics of non-equilibrium spin accumulation generated in metals or\nsemiconductors by rf magnetic field pumping is treated within a diffusive\npicture. The dc spin accumulation produced in a uniform system by a rotating\napplied magnetic field or by a precessing magnetization of a weak ferromagnet\nis in general given by a (small) fraction of hbar omega, where omega is the\nrotation or precession frequency. With the addition of a neighboring,\nfield-free region and allowing for the diffusion of spins, the spin\naccumulation is dramatically enhanced at the interface, saturating at the\nuniversal value hbar omega in the limit of long spin relaxation time. This\neffect can be maximized when the system dimensions are of the order of sqrt(2pi\nD omega), where D is the diffusion constant. We compare our results to the\ninterface spin pumping theory of A. Brataas et al. [Phys. Rev. B 66, 060404(R)\n(2002)].",
        "positive": "Near-field microwave imaging of inhomogeneous K$_x$Fe$_y$Se$_2$:\n  separation of topographic and electric features: It is important for modern scanning microwave microscopes to overcome the\neffect of the surface roughness. Here, we report microwave conductivity imaging\nof the phase-separated iron chalcogenide K$_x$Fe$_y$Se$_2$ ($x=0.8$,\n$y=1.6$-$2$), in which electric conductivity-induced contrast is distinguished\nfrom topography-induced contrast using a combination of a scanning tunneling\nmicroscope and a scanning microwave microscope (STM-SMM). We observed the\ncharacteristic modulation of the local electric property that originates from\nthe mesoscopic phase separation of the metallic and semiconducting phases in\ntwo different scanning modes: constant current (CC) mode and constant $Q$ (CQ)\nmode. In particular, CQ scanning is useful because we obtain a qualitative\nimage in which the topographic contrast is largely eliminated without\ndegradation of the spatial resolution."
    },
    {
        "anchor": "Majorana Fermions: The race continues: A critical overview is given, aimed at non-specialist audience, of the recent\nefforts to detect and manipulate Majorana fermions in solid state devices. It\nis argued that the experiments on semiconductor quantum wires proximity coupled\nto superconducting leads present tantalizing hints but not a definitive\nevidence for these elusive particles.",
        "positive": "Symmetries and dynamics in an AC-driven self-assembled quantum dot lens: Theoretical results for a single electron in multi-level system given by a\nlens-shape self-assembled quantum dot in the presence of an intense harmonic\nelectric field are presented. A non-perturbative Floquet approach is used to\nstudy the dynamical localization of the particle when going beyond the\ntwo-level approach by introducing the full spectral level structure. It is\ndiscussed the role of the different quasi-energy sidebands as the parameters of\nthe system change. It is found that the contribution of different drive\nharmonics is controlled by fine tuning of field intensity. It is also shown\nthat avoided crossings in the quasi-energy spectrum are correlated with the\nspectral force of the sidebands and dynamical state localization."
    },
    {
        "anchor": "Optimizing thermoelectric efficiency of superlattice nanowires at room\n  temperature: It is known that the figure of merit ($ZT$) of thin nanowires can be\nsignificantly enhanced at room temperature due to the reduction of phonon\nthermal conductance arising from the increase of boundary scattering of\nphonons. It is expected that the phonon thermal conductance of nanowires filled\nwith quantum dots (QDs) will be further reduced. Here we consider a\nsuperlattice nanowire (SLNW) modeled by a linear chain of strongly coupled QDs\nconnected to electrodes. We study the dependence of $ZT$ on the QD energy level\n($E_0$) (relative to the Fermi level $E_F$ in the electrodes), inter-dot\ncoupling strength ($t_c$), tunneling rate ($\\Gamma$), and temperature $T$ in\norder to optimize the design. It is found that at room temperature the maximum\npower factor occurs when $(E_0-E_F)/k_BT \\approx 2.4$ and $\\Gamma=t_c$, a\nresult almost independent of the number of QDs in SLNW as long as $t_c/k_BT\n<0.5$. By using reasonable physical parameters we show that thin SLNW with\ncross-sectional width near $3~nm$ has a potential to achieve $ZT\\ge3$.",
        "positive": "A nonlinear, geometric Hall effect without magnetic field: The classical Hall effect, the traditional means of determining\ncharge-carrier sign and density in a conductor, requires a magnetic field to\nproduce transverse voltages across a current-carrying wire. We show that along\ncurved paths -- $\\mathrm{\\textit{without}}$ any magnetic field -- geometry\nalone can produce nonlinear transverse potentials that reflect the\ncharge-carrier sign and density. We demonstrate this effect in curved graphene\nwires where the transverse potentials are consistent with the doping and change\npolarity as we switch the carrier sign. In straight wires, we measure\ntransverse potential fluctuations with random polarity demonstrating that the\ncurrent follows a complex, tortuous path. This geometrically-induced potential\noffers a sensitive characterization of inhomogeneous current flow in thin\nfilms."
    },
    {
        "anchor": "Topological protection from exceptional points in Weyl and nodal line\n  semimetals: We investigate the topological protection of surface states in Weyl and\nnodal-line semimetals by characterizing them as evanescent states when the band\nstructure is extended to complex momenta. We find in this way a sequence of\nexceptional points -that is, branch points with zero energy in the complex\nspectrum- allowing us to identify the set of surface states with complex\nmomentum signaling the decay into the 3D semimetal. From this point of view,\nWeyl and nodal-line semimetals can be classified in two types depending on the\nway surface states decay. Type A semimetals have surface states with smaller\npenetration length and oscillating decay while type B semimetals have longer\nsimple exponential decays. The difference between both types reflects in the\nway the branch cuts in the spectrum accommodate in the complex plane. The\nstability of the surface states stems in this approach from the complex\nstructure that develops around the exceptional points, with a topological\nprotection which is based on the fact that the branch cuts cannot be closed by\nsmall perturbations. We check this property when nodal-line semimetals are\nplaced under circularly polarized light, where we observe that the exceptional\npoints survive the effect of such a perturbation, though appropriate boundary\nconditions for zero-energy surface states cannot be satisfied in general due to\nthe breakdown of time-reversal invariance by the radiation field.",
        "positive": "Partial decoherence in a qubit coupled to a control register subject to\n  telegraph noise: A qubit (containing two quantum states, 1 and 2), is coupled to a control\nregister (state 3), which is subject to telegraph noise. We study the time\nevolution of the density matrix $\\rho$ of an electron which starts in some\ncoherent state on the qubit. At infinite time, $\\rho$ usually approaches the\nfully decoherent state, with $\\rho^{}_{nm}=\\delta^{}_{nm}/3$. However, when the\nHamiltonian is symmetric under $1\\leftrightarrow 2$, the element $\\rho^{}_{12}$\napproaches a non-zero real value, implying a partial coherence of the\nasymptotic state. The asymptotic density matrix depends only on ${\\rm\nRe}[\\rho^{}_{12}(t=0)]$. In several cases, the information stored on the qubit\nis protected from the noise."
    },
    {
        "anchor": "Pseudomagnetic Fields in a Locally Strained Graphene Drumhead: Recent experiments reveal that a scanning tunneling microscopy (STM) probe\ntip can generate a highly localized strain field in a graphene drumhead, which\nin turn leads to pseudomagnetic fields in the graphene that can spatially\nconfine graphene charge carriers in a way similar to a lithographically defined\nquantum dot (QD). While these experimental findings are intriguing, their\nfurther implementation in nanoelectronic devices hinges upon the knowledge of\nkey underpinning parameters, which still remain elusive. In this paper, we\nfirst summarize the experimental measurements of the deformation of graphene\nmembranes due to interactions with the STM probe tip and a back gate electrode.\nWe then carry out systematic coarse grained, (CG), simulations to offer a\nmechanistic interpretation of STM tip-induced straining of the graphene\ndrumhead. Our findings reveal the effect of (i) the position of the STM probe\ntip relative to the graphene drumhead center, (ii) the sizes of both the STM\nprobe tip and graphene drumhead, as well as (iii) the applied back-gate\nvoltage, on the induced strain field and corresponding pseudomagnetic field.\nThese results can offer quantitative guidance for future design and\nimplementation of reversible and on-demand formation of graphene QDs in\nnanoelectronics.",
        "positive": "Anomalous Nernst and Thermal Hall Effects in Tilted Weyl Semimetals: We study the anomalous Nernst and thermal Hall effects in a linearized\nlow-energy model of a tilted Weyl semimetal, with two Weyl nodes separated in\nmomentum space. For inversion symmetric tilt, we give analytic expressions in\ntwo opposite limits: for a small tilt, corresponding to a type-I Weyl\nsemimetal, the Nernst conductivity is finite and independent of the Fermi\nlevel, while for a large tilt, corresponding to a type-II Weyl semimetal, it\nacquires a contribution depending logarithmically on the Fermi energy. This\nresult is in a sharp contrast to the nontilted case, where the Nernst response\nis known to be zero in the linear model. The thermal Hall conductivity\nsimilarly acquires Fermi surface contributions, which add to the Fermi level\nindependent, zero tilt result, and is suppressed as one over the tilt parameter\nat half filling in the Type-II phase. In the case of inversion breaking tilt,\nwith the tilting vector of equal modulus in the two Weyl cones, all Fermi\nsurface contributions to both anomalous responses cancel out, resulting in zero\nNernst conductivity. We discuss two possible experimental setups, representing\nopen and closed thermoelectric circuits."
    },
    {
        "anchor": "Quantum Coherence Beyond the Thermal Length: Recent experiments have used scattering to map the flow of electrons in a\ntwo-dimensional electron gas. Among other things, the data from these\nexperiments show perseverance of regular interference fringes beyond the\nkinematic thermal length. These fringes are seen in full quantum-mechanical\nsimulations with thermal averaging, and within the phase coherence length they\ncan also be understood with a simple, single-scattering model. This effect\nprovides a new way to gauge the coherence length independent of thermal\nbroadening. Appealing to higher-order scattering, we present a mechanism by\nwhich interference fringes may survive even beyond the phase coherence length.",
        "positive": "Quantum Gates Between Mesoscopic Spin Ensembles: Quantum algorithmics with single spins poses serious technological challenges\nsuch as precision fabrication, rapid decoherence, atomic-scale addressing and\nreadout. To circumvent atomic-scale challenges, we examine the case of fully\npolarized mesoscopic spin ensembles (spin-coherent states) whose total angular\nmomenta states map to qudit submanifolds. We show that in the limit where the\nsize of the ensembles is small compared to their separation, it is possible to\ntreat them as qubits with an effective coupling strength that scales with the\nnumber of spins. If the spins within each ensemble are decoupled (e.g., via\ncontrol fields, spinning or diffusional averaging or materials engineering),\none- and two-qubit gate operations can be implemented with high fidelities."
    },
    {
        "anchor": "Topologically protected quantum transport in locally exfoliated bismuth\n  at room temperature: We report electrical conductance measurements of Bi nanocontacts created by\nrepeated tip-surface indentation using a scanning tunneling microscope at\ntemperatures of 4 K and 300 K. As a function of the elongation of the\nnanocontact we measure robust, tens of nanometers long plateaus of conductance\nG0 = 2e^2/h at room temperature. This observation can be accounted for by the\nmechanical exfoliation of a Bi(111) bilayer, a predicted QSH insulator, in the\nretracing process following a tip-surface contact. The formation of the bilayer\nis further supported by the additional observation of conductance steps below\nG0 before break-up at both temperatures. Our finding provides the first\nexperimental evidence of the possibility of mechanical exfoliation of Bi\nbilayers, of the existence of the QSH phase in a two-dimensional crystal, and,\nmost importantly, of the observation of the QSH phase at room temperature.",
        "positive": "Non-equilibrium Tunneling Spectroscopy in Carbon Nanotubes: We report measurements of the non-equilibrium electron energy distribution in\ncarbon nanotubes. Using tunneling spectroscopy via a superconducting probe, we\nstudy the shape of the local electron distribution functions, and hence energy\nrelaxation rates, in nanotubes that have bias voltages applied between their\nends. At low temperatures, electrons interact weakly in nanotubes of a few\nmicrons channel length, independent of end-to-end conductance values.\nSurprisingly, the energy relaxation rate can increase substantially when the\ntemperature is raised to only 1.5 K."
    },
    {
        "anchor": "Measuring the magnon-photon coupling in shaped ferromagnets: tuning of\n  the resonance frequency: Cavity photons and ferromagnetic spins excitations can exchange information\ncoherently in hybrid architectures, at speeds set by their mutual coupling\nstrength. Speed enhancement is usually achieved by optimizing the geometry of\nthe electromagnetic cavity. Here we show that the geometry of the ferromagnet\nplays also an important role, by setting the fundamental frequency of the\nmagnonic resonator. Using focused ion beam patterning, we vary the aspect ratio\nof different Permalloy samples reaching operation frequencies above 10 GHz\nwhile working at low external magnetic fields. Additionally, we perform broad\nband ferromagnetic resonance measurements and cavity experiments that\ndemonstrate that the magnon-photon coupling strength can be estimated using\neither open transmission lines or resonant cavities, yielding very good\nagreement. Finally, we describe a simple theoretical framework based on\nelectromagnetic and micromagnetic simulations that successfully accounts for\nthe experimental results. This approach can be used to design hybrid quantum\nsystems exploiting whatsoever magnetostatic mode excited in ferromagnets of\narbitrary size and shape and to tune their operation conditions.",
        "positive": "Modelling of the Peltier effect in magnetic multilayers: We model the charge, spin, and heat currents in ferromagnetic metal$|$normal\nmetal$|$normal metal trilayer structures in the two current model, taking into\naccount bulk and interface thermoelectric properties as well as Joule heating.\nResults include the temperature distribution as well as resistance-current\ncurves that reproduce the observed shifted parabolic characteristics. Thin\ntunneling barriers can enhance the apparent Peltier cooling. The model agrees\nwith experimental results for wide multilayer pillars, but the giant effects\nobserved for diameters $\\lesssim 100\\,$nm are still under discussion."
    },
    {
        "anchor": "Ground state and dynamics of the biased dissipative two-state system:\n  Beyond variational polaron theory: We propose a ground-state ansatz for the Ohmic spin-boson model that improves\nupon the variational treatment of Silbey and Harris for biased systems in the\nscaling limit. In particular, it correctly captures the smooth crossover\nbehaviour expected for the ground-state magnetisation when moving between the\ndelocalised and localised regimes of the model, a feature that the variational\ntreatment is unable to properly reproduce, while it also provides a lower\nground-state energy estimate in the crossover region. We further demonstrate\nthe validity of our intuitive ground-state by showing that it leads to\npredictions in excellent agreement with those derived from a non-perturbative\nBethe-ansatz technique. Finally, recasting our ansatz in the form of a\ngeneralised polaron transformation, we are able to explore the dissipative\ntwo-state dynamics beyond weak system-environment coupling within an efficient\ntime-local master equation formalism.",
        "positive": "Chiral spin-transfer torque induced by curvature gradient: This work analyzes the propagation of a transverse domain wall (DW) motion\nunder the action of an electric current along a nanowire (NW) with a curvature\ngradient. Our results evidence that the curvature gradient induces a chiral\nspin-transfer torque (CSTT) whose effect on the DW motion depends on the\ndirection along which the DW points. The origin of the CSTT is explained in\nterms of a position and phase-dependent effective field associated with the DW\nprofile and the electric current direction. Finally, our results reveal that\nthis chiral mechanism can also affect the behavior of other magnetization\ncollective modes, such as spin waves. This work shows the emergence of\ncurvature-induced chiral spin transport and highlights a new phenomenon to be\nconsidered for designing spintronic devices."
    },
    {
        "anchor": "Tunable g factor and phonon-mediated hole spin relaxation in Ge/Si\n  nanowire quantum dots: We theoretically consider g factor and spin lifetimes of holes in a\nlongitudinal Ge/Si core/shell nanowire quantum dot that is exposed to external\nmagnetic and electric fields. For the ground states, we find a large anisotropy\nof the g factor which is highly tunable by applying electric fields. This\ntunability depends strongly on the direction of the electric field with respect\nto the magnetic field. We calculate the single-phonon hole spin relaxation\ntimes T1 for zero and small electric fields and propose an optimal setup in\nwhich very large T1 of the order of tens of milliseconds can be reached.\nIncreasing the relative shell thickness or the longitudinal confinement length\nfurther prolongs T1. In the absence of electric fields, the dephasing vanishes\nand the decoherence time T2 is determined by T2 = 2 T1.",
        "positive": "Topological transitions and fractional charges induced by strain and\n  magnetic field in carbon nanotubes: We show that carbon nanotubes (CNT) can be driven through a topological phase\ntransition using either strain or a magnetic field. This can naturally lead to\nJackiw-Rebbi soliton states carrying fractionalized charges, similar to those\nfound in a domain wall in the Su-Schrieffer-Heeger model, in a setup with a\nspatially inhomogeneous strain and an axial field. Two types of fractionalized\nstates can be formed at the interface between regions with different strain: a\nspin-charge separated state with integer charge and spin zero (or zero charge\nand spin $\\pm \\hbar/2$), and a state with charge $\\pm e/2$ and spin $\\pm\n\\hbar/4$. The latter state requires spin-orbit coupling in the CNT. We show\nthat in our setup, the precise quantization of the fractionalized interface\ncharges is a consequence of the symmetry of the CNT under a combination of a\nspatial rotation by $\\pi$ and time reversal. Finally, we comment on the effects\nof many-body interaction on this phenomena."
    },
    {
        "anchor": "Simulated Charge Stability in a MOSFET Linear Quantum Dot Array: In this study, we address challenges in designing quantum information\nprocessors based on electron spin qubits in electrostatically-defined quantum\ndots (QDs). Numerical calculations of charge stability diagrams are presented\nfor a realistic double QD device geometry. These methods generaize to linear QD\narrays, and are based on determining the effective parameters of a Hubbard\nmodel Hamiltonian that is then diagonalized to find the many-electron ground\nstate energy. These calculations enable the identification of gate voltage\nranges that maintain desired charge states during qubit manipulation, and also\naccount for electrical cross-talk between QDs. As a result, the methods\npresented here promise to be a valuable tool for developing scalable spin qubit\nquantum processors.",
        "positive": "Controlling spin Hall effect by using a band anticrossing and\n  nonmagnetic impurity scattering: The spin Hall effect (SHE) is one of the promising phenomena to utilize a\nspin current as spintronics devices, and the theoretical understanding of its\nmicroscopic mechanism is essential to know how to control its response.\nAlthough the SHE in multiorbital systems without inversion symmetry (IS) is\nexpected to show several characteristic properties due to the cooperative roles\nof orbital degrees of freedom and a lack of IS, a theoretical understanding of\nthe cooperative roles has been lacking. To clarify the cooperative roles, we\nstudy the spin Hall conductivity (SHC) derived by the linear-response theory\nfor a $t_{2g}$-orbital tight-binding model of the $[001]$ surface or interface\nof Sr$_2$RuO$_4$ in the presence of dilute nonmagnetic impurities. We find that\nthe band anticrossing, arising from a combination of orbital degrees of freedom\nand a lack of IS, causes an increase of magnitude and a sign change of the SHC\nat some nonmagnetic impurity concentrations. Since a similar mechanism for\ncontrolling the magnitude and sign of the response of Hall effects works in\nother multiorbital systems without IS, our mechanism provides an ubiquitous\nmethod to control the magnitude and sign of the response of Hall effects in\nsome multiorbital systems by introducing IS breaking and tuning of the\nnonmagnetic impurity concentration."
    },
    {
        "anchor": "Non-Hermitian semi-Dirac semi-metals: Recently, many novel and exotic phases have been proposed by considering the\nrole of topology in non-Hermitian systems, and their emergent properties are of\nwide current interest. In this work we propose the non-Hermitian generalization\nof semi-Dirac semimetals, which feature a linear dispersion along one momentum\ndirection and a quadratic one along the other. We study the topological phase\ntransitions in such two-dimensional semi-Dirac semimetals in the presence of a\nparticle gain-and-loss term. We show that such a non-Hermitian term creates\nexceptional points originating out of each semi-Dirac point. We map out the\ntopological phase diagram of our model, using winding number and vorticity as\ntopological invariants of the system. By means of numerical and analytical\ncalculations, we examine the nature of edge states for different types of\nsemi-Dirac models and establish bulk-boundary correspondence and absence of the\nnon-Hermitian skin effect, in one class. On the other hand, for other classes\nof semi-Dirac models with asymmetric hopping, we restore the non-Hermitian skin\neffect, an anomalous feature usually present in non-Hermitian topological\nsystems.",
        "positive": "The Effect of Interactions on the Conductance of Graphene Nanoribbons: We study the effects of the interaction between electrons and holes on the\nconductance G of quasi-one-dimensional graphene systems.\n  We first consider as a benchmark the limit in which all interactions are\nnegligible, recovering the predictions of the tight-binding approximation for\nthe spectrum of the system, and the well-known result G=4 e^2/h for the lowest\nconductance quantum. Then we consider an exactly solvable field theoretical\nmodel in which the electro-magnetic interactions are effectively local.\nFinally, we use the effective field theory formalism to develop an exactly\nsolvable model in which we also include the effect of non-local interactions.\nWe find that such interactions turn the nominally metallic armchair graphene\nnanoribbon into a semi-conductor, while the short-range interactions lead to a\ncorrection to the G=4 e^2/h formula."
    },
    {
        "anchor": "Spin-Hall Effect in A Symmetric Quantum Wells by A Random Rashba Field: Changes dopant ion concentrations in the sides of a symmetric quantum well\nare known to create a random Rashba-type spin-orbit coupling. Here we\ndemonstrate that, as a consequence, a finite size spin-Hall effect is also\npresent. Our numerical algorithm estimates the result of the Kubo formula for\nthe spin-Hall conductivity, by using a tight-binding approximation of the\nHamiltonian in the framework of a time-dependent Green's function formalism,\nwell suited for very large systems.",
        "positive": "The Berry dipole photovoltaic demon and the thermodynamics of\n  photo-current generation within the optical gap of metals: We dismantle the previously held misconception that it is impossible for bulk\nrectification mechanisms to induce a net DC electric current when the frequency\nof the impinging radiation lies within the optical gap of a metal in the limit\nof small carrier relaxation rates. We argue that generically such in-gap\nrectification mechanisms are irreversible and accompanied by a continuous\nexchange of energy with a heat bath and must also be necessarily accompanied by\na small but finite absorption of radiation in order to guarantee the positivity\nof the net entropy production and abide by the second law of thermodynamics. We\nshow, however, that the intra-band non-linear Hall effect arising from the\nBerry curvature is a special kind of in-gap rectification mechanism that\nbehaves as a ``photo-voltaic demon'', namely it can operate as an ideal\nreversible and dissipationless conveyor of energy between the radiation and an\nexternal circuit. Its reversible nature allows for an interesting mode of\noperation as an amplifier of circularly polarized light, whose efficiency can\napproach 100%, and which could be technologically promising especially in the\ninfrared frequency range."
    },
    {
        "anchor": "Interacting electrons in a magnetic field: mapping quantum mechanics to\n  a classical ersatz-system: Solving the quantum-mechanical many-body problem requires scalable\ncomputational approaches, which are rooted in a good understanding of the\nphysics of correlated electronic systems. Interacting electrons in a magnetic\nfield display a huge variety of eigenstates with different internal structures,\nwhich have been probed experimentally in the Hall effect. The advent of\nhigh-performing graphics processing units has lead to a boost in computational\nspeed in particular for classical systems. In the absence of a\nquantum-computer, it is thus of importance to see how quantum-mechanical\nproblems can be cast into a seemingly classical dynamics, which can be\nefficiently implemented. At the same time, such mappings provide insights into\nthe quantum-to-classical transition of many-body systems.",
        "positive": "Single Magnetic Atom on a Surface: Anisotropy Energy and Spin Density: Studying single-atom magnetic anisotropy on surfaces enables the exploration\nof the smallest magnetic storage bit that can be built. In this work, magnetic\nanisotropy of a single rare-earth atom on a surface is studied computationally\nfor the first time. The single adatom and its substrate surface are chosen to\nbe a Dysprosium (Dy) atom and a copper-nitrite surface, respectively, where\nsingle transition-metal magnetic atoms on the same surface were previously\nstudied one atom at a time by scanning tunneling microscopes. We propose\nunconventional f and d subshell symmetries so that following the\nfirst-principles calculations, simple pictorial analyses of the spin-density\ndistribution can be performed for the first time, independently for both a\nrare-earth atom Dy and a transition-metal Fe. The magnetic anisotropy energy of\nDy on the surface is calculated to be a factor of five larger than the previous\nhighest one, reaching a record-high value of 31 meV."
    },
    {
        "anchor": "Charge Motion along Polynucleotide Chains in a Constant Electric Field\n  Depends on the Charge Coupling Constant with Chain Displacements: Various regimes of a charge motion along a chain in a constant electric field\nare investigated. This motion is simulated on the basis of the Holstein model.\nEarlier studies demonstrate a possibility of a uniform motion of a charge in a\nconstant electric field over very long distances. For small values of the\nelectric field intensity a Holstein polaron can move at a constant velocity. As\nthe electric field intensity increases, a charge motion acquires oscillatorily\ncharacter, performing Bloch oscillations. Since the charge motion depends on\nthe whole set of the system parameters the character of the motion depends not\nonly on the value of the electric field intensity. Therefore, the electric\nfield intensity for which the uniform motion takes place differs for chains\nwith different parameters. The character of the charge motion and distribution\nis considered in chains with different values of the constant of coupling\nbetween the charge and the displacements of the chain. It is shown that the\nvalues of the electric field intensity for which the regime of a charge motion\nchanges are different in chains with different values of the coupling constant.\nIt is also demonstrated that for one and the same value of the electric field\nintensity, in chains with different values of the coupling constant either a\nuniform motion or an oscillatory motion, or a stationary polaron can be\nobserved.",
        "positive": "Consequences of the thermal dependence of spin orbit coupling in\n  semiconductors: The $\\vec{k}.\\vec{p}$ perturbation theory in semiconductor modifies some spin\nrelated parameters of the semi-conducting system. Furthermore, renormalization\nof the Kane model parameters occurs when temperature appears in the scenario.\nIn this paper, we have analysed the consequences of this renormalized Kane\nparameters on some spin transport issues. It is noteworthy to study that the\ntemperature corrected scenario, explained here can open up a new direction\ntowards the spin calorimetric applications in semiconductors."
    },
    {
        "anchor": "Electron transport through a quantum interferometer with side-coupled\n  quantum dots: Green's function approach: We study electron transport through a quantum interferometer with\nside-coupled quantum dots. The interferometer, threaded by a magnetic flux\n$\\phi$, is attached symmetrically to two semi-infinite one-dimensional metallic\nelectrodes. The calculations are based on the tight-binding model and the\nGreen's function method, which numerically compute the conductance-energy and\ncurrent-voltage characteristics. Our results predict that under certain\nconditions this particular geometry exhibits anti-resonant states. These states\nare specific to the interferometric nature of the scattering and do not occur\nin conventional one-dimensional scattering problems of potential barriers. Most\nimportantly we show that, such a simple geometric model can also be used as a\nclassical XOR gate, where the two gate voltages, viz, $V_a$ and $V_b$, are\napplied, respectively, in the two dots those are treated as the two inputs of\nthe XOR gate. For $\\phi=\\phi_0/2$ ($\\phi_0=ch/e$, the elementary flux-quantum),\na high output current (1) (in the logical sense) appears if one, and only one,\nof the inputs to the gate is high (1), while if both inputs are low (0) or both\nare high (1), a low output current (0) appears. It clearly demonstrates the XOR\ngate behavior and this aspect may be utilized in designing the electronic logic\ngate.",
        "positive": "Out-of-time-ordered commutators in Dirac--Weyl systems: Quantum information stored in local operators spreads over other degrees of\nfreedom of the system during time evolution, known as scrambling. This process\nis conveniently characterized by the out-of-time-order commutators (OTOC),\nwhose time dependence reveals salient aspects of the system's dynamics. Here we\nstudy the spatially local spin correlation function i.e., the expectation value\nof spin commutator and the corresponding OTOC of Dirac--Weyl systems in one,\ntwo, and three spatial dimensions. The OTOC can be written as the square of the\nexpectation value of the commutator and the variance of the commutator. In\nprinciple, the problem features two energy scales, the chemical potential, and\nthe high energy cutoff. We find that only the latter is dominant, therefore the\ntime evolution is separated into only two different regions. The spin\ncorrelation function grows linearly with time initially and decays as $t^{-2}$\nfor late times. The OTOC reveals a universal $t^2$ initial growth from both the\ncommutator and the variance while its late time decay, $t^{-2}$ originates from\nthe variance of the commutator. This late time decay is identified as a\ncharacteristic signature or Dirac-Weyl fermions. These features remain present\nalso at finite temperatures. Our results indicate that Dirac--Weyl systems are\nslow information scramblers and are essential when additional channels for\nscrambling, i.e., interaction or disorder are analyzed."
    },
    {
        "anchor": "Thermal noise and dephasing due to electron interactions in non-trivial\n  geometries: We study Johnson-Nyquist noise in macroscopically inhomogeneous disordered\nmetals and give a microscopic derivation of the correlation function of the\nscalar electric potentials in real space. Starting from the interacting\nHamiltonian for electrons in a metal and the random phase approximation, we\nfind a relation between the correlation function of the electric potentials and\nthe density fluctuations which is valid for arbitrary geometry and\ndimensionality. We show that the potential fluctuations are proportional to the\nsolution of the diffusion equation, taken at zero frequency. As an example, we\nconsider networks of quasi-1D disordered wires and give an explicit expression\nfor the correlation function in a ring attached via arms to absorbing leads. We\nuse this result in order to develop a theory of dephasing by electronic noise\nin multiply-connected systems.",
        "positive": "Microwave-induced magnetooscillations and signatures of zero-resistance\n  states in phonon-drag voltage in two-dimensional electron systems: We observe the phonon-drag voltage oscillations correlating with the\nresistance oscillations under microwave irradiation in a two-dimensional\nelectron gas in perpendicular magnetic field. This phenomenon is explained by\nthe influence of dissipative resistivity modified by microwaves on the\nphonon-drag voltage perpendicular to the phonon flux. When the lowest-order\nresistance minima evolve into zero-resistance states, the phonon-drag voltage\ndemonstrates sharp features suggesting that current domains associated with\nthese states can exist in the absence of external dc driving."
    },
    {
        "anchor": "Polarization of Bloch electrons and Berry phase in the presence of\n  electromagnetic fields: We consider Bloch electrons in the presence of the uniform electromagnetic\nfield in two- and three-dimensions. It is renowned that the quantized Hall\neffect occurs in such systems. We suppose a weak and homogeneous electric field\nrepresented by the time-dependent vector potential which is changing\nadiabatically. The adiabatic process can be closed in the parameter space and a\nBerry phase is generated. In the system, one can define the macroscopic\nelectric polarization whose time derivative is equivalent to the quantized Hall\ncurrent and its conductivity is written by the Chern number. Then, the\npolarization is induced perpendicular to the electric field. We show that the\ninduced polarization per a cycle in the parameter space is quantized and\nclosely related to the Berry phase as well as the Chern number. The process is\nadiabatic and the system always remains the ground state, then, the\npolarization is quite different from the usual dielectric polarization and has\nsome similarity to the spontaneous polarization in the crystalline dielectrics\nwhich is also written by the Berry phase. We also point out the relation\nbetween our results and the adiabatic pumping.",
        "positive": "Enhancement of Persistent Current in Metal Rings by Correlated Disorder: We study analytically the effect of a correlated random potential on the\npersistent current in a one-dimensional ring threaded by a magnetic flux\n$\\phi$, using an Anderson tight-binding model. In our model, the system of\n$N=2M$ atomic sites of the ring is assumed to be partitioned into $M$ pairs of\nidentical nearest-neighbour sites (dimers). The site energies for different\ndimers are taken to be uncorrelated gaussian variables. For this system we\nobtain the exact flux-dependent energy levels to second order in the random\nsite energies, using an earlier exact transfer matrix perturbation theory.\nThese results are used to study the mean persistent current generated by\n$N_e\\leq N$ spinless electrons occupying the $N_e$ lowest levels of the\nflux-dependent energy band at zero temperature. Detailed analyses are carried\nout in the limit $1\\ll N_e\\ll N$ and for a half-filled band ($N_e=N/2$), for\nmagnetic fluxes $-1/2 <\\phi/\\phi_0<1/2$. While the uncorrelated disorder leads\nto a reduction of the persistent current, the disorder correlation acts to\nenhance it. In particular, in the half-filled band case the correlated disorder\nleads to a global flux-dependent enhancement of persistent current which has\nthe same form for even and odd $N_e$. At low filling of the energy band the\neffect of the disorder on the persistent current is found to depend on the\nparity of $N_e$: the correlated disorder yields a reduction of the current for\nodd $N_e$ and an enhancement of the current for even $N_e$."
    },
    {
        "anchor": "First Principles Study of Bismuth Films at Transition Metal Grain\n  Boundaries: Recent experiments suggest that Bi impurities segregate to form bilayer films\non Ni and Cu grain boundaries but do not segregate in Fe. To explain these\nphenomena, we study the total energies of Bi films on transition metal (TM)\n$\\Sigma$3(111) and $\\Sigma$5(012) GBs using density functional theory. Our\nresults agree with the observed stabilities. We propose a model to predict Bi\nbilayer stability at Ni GBs which suggests that Bi bilayer is not stable on\n(111) twist CSL GBs but is stable in most (100) twist CSL GBs. We investigate\nthe interaction and bonding character between Bi and TMs to explain the\ndifferences among TMs based on localization of orbitals and magnetism.",
        "positive": "Direct observation of non-equilibrium spin population in\n  quasi-one-dimensional nanostructures: Observation of the interplay between interacting energy levels of two spin\nspecies is limited by the difficulties in continuously tracking energy levels,\nand thus leaves spin transport in quantum wires still not well understood. We\npresent a dc conductance feature in the non-equilibrium transport regime, a\ndirect indication that the first one-dimensional subband is filled mostly by\none spin species only. How this anomalous spin population changes with magnetic\nfield and source-drain bias is directly measured. We show the source-drain bias\nchanges spin polarisation in semiconductor nanowires, providing a fully\nelectrical method for the creation and manipulation of spin polarization as\nwell as spin-polarized currents."
    },
    {
        "anchor": "Effect of a skin-deep surface zone on formation of two-dimensional\n  electron gas at a semiconductor surface: Two dimensional electron gases (2DEGs) at surfaces and interfaces of\nsemiconductors are described straightforwardly with a 1D self-consistent\nPoisson-Schr\\\"{o}dinger scheme. However, their band energies have not been\nmodeled correctly in this way. Using angle-resolved photoelectron spectroscopy\nwe study the band structures of 2DEGs formed at sulfur-passivated surfaces of\nInAs(001) as a model system. Electronic properties of these surfaces are tuned\nby changing the S coverage, while keeping a high-quality interface, free of\ndefects and with a constant doping density. In contrast to earlier studies we\nshow that the Poisson-Schr\\\"{o}dinger scheme predicts the 2DEG bands energies\ncorrectly but it is indispensable to take into account the existence of the\nphysical surface. The surface substantially influences the band energies beyond\nsimple electrostatics, by setting nontrivial boundary conditions for 2DEG\nwavefunctions.",
        "positive": "Skyrmion dynamics in a frustrated ferromagnetic film and current-induced\n  helicity locking-unlocking transition: The helicity-orbital coupling is an intriguing feature of magnetic skyrmions\nin frustrated magnets. Here, we explore the skyrmion dynamics in a frustrated\nmagnet based on the $J_{1}$-$J_{2}$-$J_{3}$ classical Heisenberg model\nexplicitly by including the dipole-dipole interaction. The skyrmion energy\nacquires a helicity dependence due to the dipole-dipole interaction, resulting\nin the current-induced translational motion with a fixed helicity. The lowest\nenergy states are the degenerate Bloch-type states, which can be used for\nbuilding the binary memory. By increasing the driving current, the helicity\nlocking-unlocking transition occurs, where the translational motion changes to\nthe rotational motion. Furthermore, we demonstrate that two skyrmions can\nspontaneously form a bound state. The separation of the bound state forced by a\ndriving current is also studied. In addition, we show the annihilation of a\npair of skyrmion and antiskyrmion. Our results reveal the distinctive\nfrustrated skyrmions may enable viable applications in topological magnetism."
    },
    {
        "anchor": "A Microscopic and Spectroscopic View of Quantum Tunneling of\n  Magnetization: This chapter takes a microscopic view of quantum tunneling of magnetization\n(QTM) in single-molecule magnets (SMMs), focusing on the interplay between\nexchange and anisotropy. Careful consideration is given to the relationship\nbetween molecular symmetry and the symmetry of the spin Hamiltonian that\ndictates QTM selection rules. Higher order interactions that can modify the\nusual selection rules are shown to be very sensitive to the exchange strength.\nIn the strong coupling limit, the spin Hamiltonian possess rigorous $D_{2h}$\nsymmetry (or $C_{\\infty}$ in high-symmetry cases). In the case of weaker\nexchange, additional symmetries may emerge through mixing of excited spin\nstates into the ground state. Group theoretic arguments are introduced to\nsupport these ideas, as are extensive results of magnetization hysteresis and\nelectron paramagnetic resonance measurements.",
        "positive": "Observation of the fractional quantum spin Hall effect in moir\u00e9 MoTe2: Quantum spin Hall (QSH) insulators are two-dimensional electronic materials\nthat have a bulk band gap like an ordinary insulator but have topologically\nprotected pairs of edge modes of opposite chiralities. To date, experimental\nstudies have found only integer QSH insulators with counter-propagating\nup-spins and down-spins at each edge leading to a quantized conductance\nG0=e^2/h. Here we report transport evidence of a fractional QSH insulator in\n2.1-degree-twisted bilayer MoTe2, which supports spin-Sz conservation and flat\nspin-contrasting Chern bands. At filling factor v = 3 of the moir\\'e valence\nbands, each edge contributes a conductance 3/2 G0 with zero anomalous Hall\nconductivity. The state is likely a time-reversal pair of the even-denominator\n3/2-fractional Chern insulators. Further, at v = 2, 4 and 6, we observe a\nsingle, double and triple QSH insulator with each edge contributing a\nconductance G0, 2G0 and 3G0, respectively. Our results open up the possibility\nof realizing time reversal symmetric non-abelian anyons and other unexpected\ntopological phases in highly tunable moir\\'e materials."
    },
    {
        "anchor": "Controllable Goos-H\u00e4nchen shifts and spin beam splitter for\n  ballistic electrons in a parabolic quantum well under a uniform magnetic\n  field: The quantum Goos-H\\\"{a}nchen shift for ballistic electrons is investigated in\na parabolic potential well under a uniform vertical magnetic field. It is found\nthat the Goos-H\\\"{a}nchen shift can be negative as well as positive, and\nbecomes zero at transmission resonances. The beam shift depends not only on the\nincident energy and incidence angle, but also on the magnetic field and Landau\nquantum number. Based on these phenomena, we propose an alternative way to\nrealize the spin beam splitter in the proposed spintronic device, which can\ncompletely separate spin-up and spin-down electron beams by negative and\npositive Goos-H\\\"{a}nchen shifts.",
        "positive": "Electrical operation of planar Ge hole spin qubits in an in-plane\n  magnetic field: In this work we present a comprehensive theory of spin physics in planar Ge\nhole quantum dots in an in-plane magnetic field, where the orbital terms play a\ndominant role in qubit physics, and provide a brief comparison with\nexperimental measurements of the angular dependence of electrically driven spin\nresonance. We focus the theoretical analysis on electrical spin operation,\nphonon-induced relaxation, and the existence of coherence sweet spots. We find\nthat the choice of magnetic field orientation makes a substantial difference\nfor the properties of hole spin qubits. Furthermore, although the\nSchrieffer-Wolff approximation can describe electron dipole spin resonance\n(EDSR), it does not capture the fundamental spin dynamics underlying qubit\ncoherence. Specifically, we find that: (i) EDSR for in-plane magnetic fields\nvaries non-linearly with the field strength and weaker than for perpendicular\nmagnetic fields; (ii) The EDSR Rabi frequency is maximized when the a.c.\nelectric field is aligned parallel to the magnetic field, and vanishes when the\ntwo are perpendicular; (iii) The Rabi ratio $T_1/T_\\pi$, i.e. the number of\nEDSR gate operation per unit relaxation time, is expected to be as large as\n$5{\\times}10^5$ at the magnetic fields used experimentally; (iv) The orbital\nmagnetic field terms make the in-plane $g$-factor strongly anisotropic in a\nsqueezed dot, in excellent agreement with experimental measurements; (v) The\ncoherence sweet spots do not exist in an in-plane magnetic field, as the\norbital magnetic field terms expose the qubit to all components of the defect\nelectric field. These findings will provide a guideline for experiments to\ndesign ultrafast, highly coherent hole spin qubits in Ge."
    },
    {
        "anchor": "Strong interlayer charge transfer due to exciton condensation in an\n  electrically-isolated GaAs quantum well bilayer: We introduce a design of electrically isolated floating bilayer GaAs quantum\nwells (QW) in which application of a large gating voltage controllably and\nhighly reproducibly induces charges that remain trapped in the bilayer after\nremoval of the gating voltage. At smaller gate voltages, the bilayer is fully\nelectrically isolated from external electrodes by thick insulating barriers.\nThis design permits full control of the total and differential densities of two\ncoupled 2D electron systems. The floating bilayer design provides a unique\napproach for studying systems inaccessible by simple transport measurements. It\nalso provides the ability to measure the charge transfer between the layers,\neven when the in-plane resistivities of the 2D systems diverge. We measure the\ncapacitance and inter-layer tunneling spectra of the QW bilayer with\nindependent control of the top and bottom layer electron densities. Our\nmeasurements display strongly enhanced inter-layer tunneling current at the\ntotal filling factor of 1, a signature of exciton condensation of a strongly\ninterlayer-correlated bilayer system. With fully tunable densities of\nindividual layers, the floating bilayer QW system provides a versatile platform\nto access previously unavailable information on the quantum phases in electron\nbilayer systems.",
        "positive": "Magic angle twisted bilayer graphene as a highly efficient quantum Otto\n  engine: At a discrete set of magic angles, twisted bilayer graphene has been shown to\nhost extraordinarily flat bands, correlated insulating states, unconventional\nsuperconductivity, and distinct Landau level degeneracies. In this work, we\ndesign a highly efficient quantum Otto engine using a twisted bilayer graphene\nsample. Flat bands, which occur at magic angles, make the prospect of\nextracting useful work from our Otto engine lucrative. We use an eight-band\ncontinuum model of twisted bilayer graphene to compute efficiencies and work\noutputs for magic and non-magic angle twists, and compare the results with an\n$AB$ stacked bilayer and a monolayer. It is observed that the efficiency varies\nsmoothly with the twist angle and the maximum is attained at the magic angle."
    },
    {
        "anchor": "Fermionic analogue of black hole radiation with a super high Hawking\n  temperature: Measurement of gravitational Hawking radiation of black hole (BH) is\nprohibitive because of an extremely low Hawking temperature (TH). Here we\ndemonstrate a fermionic analog of BH with a super high TH ~ 3 K, which is\nseveral orders of magnitude higher than previous works. We propose that\nFloquet-Dirac states, formed in a periodically laser driven two-dimensional\nblack phosphorous thin film, can be designed with a spatial gradient to mimic\nthe \"gravity\" felt by fermionic quasiparticles as that for a Schwarzschild BH\n(SBH). Quantum tunneling of electrons from a type-II Dirac cone (inside BH) to\na type-I Dirac cone (outside) emits a SBH-like Hawking radiation spectrum.",
        "positive": "Reduced dielectric screening and enhanced energy transfer in single and\n  few-layer MoS2: We report highly efficient non-radiative energy transfer from cadmium\nselenide (CdSe) quantum dots to monolayer and few-layer molybdenum disulfide\n(MoS2). The quenching of the donor quantum dot photoluminescence increases as\nthe MoS2 flake thickness decreases, with the highest efficiency (>95%) observed\nfor monolayer MoS2. This counterintuitive result arises from reduced dielectric\nscreening in thin layer semiconductors having unusually large permittivity and\na strong in-plane transition dipole moment, as found in MoS2. Excitonic energy\ntransfer between a 0D emitter and a 2D absorber is fundamentally interesting\nand enables a wide range of applications including broadband optical\ndown-conversion, optical detection, photovoltaic sensitization, and color\nshifting in light-emitting devices."
    },
    {
        "anchor": "Hydrodynamic Navier-Stokes equations in two-dimensional systems with\n  Rashba spin-orbit coupling: We study a two-dimensional (2D) electron system with a linear spectrum in the\npresence of Rashba spin-orbit (RSO) coupling in the hydrodynamic regime. We\nderive a semiclassical Boltzmann equation with a collision integral due to\nCoulomb interactions in the basis of the eigenstates of the system with RSO\ncoupling. Using the local equilibrium distribution functions, we obtain a\ngeneralized hydrodynamic Navier-Stokes equation for electronic systems with RSO\ncoupling. In particular, we discuss the influence of the spin-orbit coupling on\nthe viscosity and the enthalpy of the system and present some of its observable\neffects in hydrodynamic transport.",
        "positive": "Weyl semimetals from noncentrosymmetric topological insulators: We study the problem of phase transitions from 3D topological to normal\ninsulators without inversion symmetry. In contrast with the conclusions of some\nprevious work, we show that a Weyl semimetal always exists as an intermediate\nphase regardless of any constriant from lattice symmetries, although the\ninterval of the critical region is sensitive to the choice of path in the\nparameter space and can be very narrow. We demonstrate this behavior by\ncarrying out first-principles calculations on the noncentrosymmetric\ntopological insulators LaBiTe$_3$ and LuBiTe$_3$ and the trivial insulator\nBiTeI. We find that a robust Weyl-semimetal phase exists in the solid solutions\nLaBi$_{1-x}$Sb$_x$Te$_3$ and LuBi$_{1-x}$Sb$_x$Te$_3$ for\n$x\\!\\approx\\!38.5-41.9$\\% and $x\\!\\approx\\!40.5-45.1$\\% respectively. A\nlow-energy effective model is also constructed to describe the critical\nbehavior in these two materials. In BiTeI, a Weyl semimetal also appears with\napplied pressure, but only within a very small pressure range, which may\nexplain why it has not been experimentally observed."
    },
    {
        "anchor": "Octahedral tilt independent magnetism in confined GdTiO$_3$ films: Polarized neutron reflectometry measurements are presented exploring the\nevolution of ferrimagnetism in GdTiO$_3$ films as they are confined between\nSrTiO$_3$ layers of variable thicknesses. As GdTiO$_3$ films approach the thin\nlayer limit and are confined within a substantially thicker SrTiO$_3$ matrix,\nthe TiO$_6$ octahedral tilts endemic to GdTiO$_3$ coherently relax toward the\nundistorted, cubic phase of SrTiO$_3$. Our measurements reveal that the\nferrimagnetic state within the GdTiO$_3$ layers survives as the TiO$_6$\noctahedral tilts in the GdTiO$_3$ layers are suppressed. Furthermore, our data\nsuggest that a magnetic dead layer develops within the GdTiO$_3$ layer at each\nGdTiO$_3$/ SrTiO$_3$ interface. The ferrimagnetic moment inherent to the core\nGdTiO$_3$ layers is negligibly (in models with dead layers) or only weakly (in\nmodels without dead layers) impacted as the octahedral tilt angles are\nsuppressed by more than 50$\\%$ and the $t_{2g}$ bandwidth is dramatically\nrenormalized.",
        "positive": "A two-atom electron pump: The fabrication of single atom transistors paved the way for electronics\nbased on single dopants. Recently the spectrum of a single dopant was measured\nelectrically by coupling two such devices. The next step towards promising\nfunctionalities for future nanoelectronics consists in manipulating a single\nelectron over two dopants. Here we demonstrate electron pumping through two\nphosphorus donors in series implanted in a silicon nanowire. While quantized\npumping is achieved in the low frequency adiabatic regime, we observe\nremarkable features at higher frequency when the charge transfer is limited by\nthe different tunneling rates. The transitions between quantum states are\nmodeled involving a Landau-Zener transition, allowing to reproduce in detail\nthe characteristic signatures observed in the non-adiabatic regime."
    },
    {
        "anchor": "Resonant Measurement of Non-Reorientable Spin-Orbit Torque from a\n  Ferromagnetic Source Layer Accounting for Dynamic Spin Pumping: Using a multilayer structure containing (cobalt detector layer)/(copper\nspacer)/(Permalloy source layer), we show experimentally how the\nnon-reorientable spin-orbit torque generated by the Permalloy source layer (the\ncomponent of spin-orbit torque that does not change when the Permalloy\nmagnetization is rotated) can be measured using spin-torque ferromagnetic\nresonance (ST-FMR) with lineshape analysis. We find that dynamic spin pumping\nbetween the magnetic layers exerts torques on the magnetic layers as large or\nlarger than the spin-orbit torques, so that if dynamic spin pumping is\nneglected the result would be a large overestimate of the spin-orbit torque.\nNevertheless, the two effects can be separated by performing ST-FMR as a\nfunction of frequency. We measure a non-reorientable spin torque ratio\n$\\xi_{\\text{Py}} = 0.04 \\pm 0.01$ for spin current flow from Permalloy through\nan 8 nm Cu spacer to the Co, and a strength of dynamic spin pumping that is\nconsistent with previous measurements by conventional ferromagnetic resonance.",
        "positive": "Quantum simulation of ZnO nanowire piezotronics: We address the problem of quantum transport in a nanometre sized two-terminal\nZnO device subject to an external strain. The two junctions formed between the\nelectrodes and the ZnO are generally taken as Ohmic and Schottky type,\nrespectively. Unlike the conventional treatment to the piezopotential, we treat\nit as a potential barrier which is only induced at the interfaces. By\ncalculating the transmission coefficient of a Fermi-energized electron that\nflows from one end to the other, it is found that the piezopotential has the\neffect of modulating the voltage threshold of the current flowing. The\ncalculations are based on the quantum scattering theory. The work is believed\nto pave the way for investigating the quantum piezotronics."
    },
    {
        "anchor": "Fluctuation theorem for heat transport probed by a thermal electrode: We analyze the full-counting statistics of the electric heat current flowing\nin a two-terminal quantum conductor whose temperature is probed by a third\nelectrode (\"probe electrode\"). In particular we demonstrate that the\ncumulant-generating function obeys the fluctuation theorem in the presence of a\nconstant magnetic field. The analysis is based on the scattering matrix of the\nthree-terminal junction (comprising of the two electronic terminals and the\nprobe electrode), and a separation of time scales: it is assumed that the rapid\ncharge transfer across the conductor and the rapid relaxation of the electrons\ninside the probe electrode give rise to much slower energy fluctuations in the\nlatter. This separation allows for a stochastic treatment of the probe\ndynamics, and the reduction of the three-terminal setup to an effective\ntwo-terminal one. Expressions for the lowest nonlinear transport coefficients,\ne.g., the linear-response heat-current noise and the second nonlinear thermal\nconductance, are obtained and explicitly shown to preserve the symmetry of the\nfluctuation theorem for the two-terminal conductor. The derivation of our\nexpressions which is based on the transport coefficients of the three-terminal\nsystem explicitly satisfying the fluctuation theorem, requires the full\ncalculations of vertex corrections.",
        "positive": "Rectification of laser-induced electronic transport through molecules: We study the influence of laser radiation on the electron transport through a\nmolecular wire weakly coupled to two leads. In the absence of a generalized\nparity symmetry, the molecule rectifies the laser induced current, resulting in\ndirected electron transport without any applied voltage. We consider two\ngeneric ways of dynamical symmetry breaking: mixing of different harmonics of\nthe laser field and molecules consisting of asymmetric groups. For the\nevaluation of the nonlinear current, a numerically efficient formalism is\nderived which is based upon the Floquet solutions of the driven molecule. This\npermits a treatment in the non-adiabatic regime and beyond linear response."
    },
    {
        "anchor": "Charge to Spin Conversion in van der Waals Metal NbSe2: Quantum materials with a large charge current-induced spin polarization are\npromising for next-generation all-electrical spintronic science and technology.\nVan der Waals metals with high spin-orbit coupling and novel spin textures have\nattracted significant attention for an efficient charge to spin conversion\nprocess. Here, we demonstrate the electrical generation of spin polarization in\nNbSe2 up to room temperature. To probe the current-induced spin polarization in\nNbSe2, we used a graphene-based non-local spin-valve device, where the\nspin-polarization in NbSe2 is efficiently injected and detected using non-local\nspin-switch and Hanle spin precession measurements. A significantly higher\ncharge-spin conversion in NbSe2 is observed at a lower temperature, below the\nsuperconducting transition temperature Tc ~ 7 K of NbSe2. However, the\ncharge-spin conversion signal could only be observed with a higher bias current\nabove the superconducting critical current, limiting the observation of the\nsignal only to the non-superconducting state of NbSe2. Systematic measurements\nprovide the possible origins of the spin polarization to be predominantly due\nto the spin Hall effect or Rashba-Edelstein effect in NbSe2, considering\ndifferent symmetry allowed charge-spin conversion processes.",
        "positive": "Macroscopic Quantum Coherence in Molecular Magnets: We study macroscopic quantum coherence in antiferromagnetic molecular magnets\nin the presence of magnetic fields. Such fields generate artificial tunnel\nbarriers with externally tunable strength. We give detailed semi-classical\npredictions for the tunnel splitting in various regimes for low and high\nmagnetic fields. We show that the tunneling dynamics of the Neel vector can be\ndirectly measured via the static magnetization and the specific heat. We also\nreport on a new quantum phase arising from fluctuations. The analytic results\nare complemented by numerical simulations."
    },
    {
        "anchor": "Distribution of energy dissipated by a driven two-level system: In the context of fluctuation relations, we study the distribution of energy\ndissipated by a driven two-level system. Incorporating an energy counting field\ninto the well known spin-boson model enables us to calculate the distribution\nfunction of the amount of energy exchanged between the system and the bath. We\nalso derive the conditional distribution functions of the energy exchanged with\nthe bath for particular initial and/or final states of the two-level system. We\nconfirm the symmetry of the conditional distribution function expected from the\ntheory of fluctuation relations. We also find that the conditional distribution\nfunctions acquire considerable quantum corrections at times shorter or of the\norder of the dephasing time. Our findings can be tested using solid-state\nqubits.",
        "positive": "High frequency impact ionization and nonlinearity of photocurrent\n  induced by intense terahertz radiation in HgTe-based quantum well structures: We report on a strong nonlinear behavior of the photogalvanics and\nphotoconductivity under excitation of HgTe quantum wells (QWs) by intense\nterahertz (THz) radiation. The increasing radiation intensity causes an\ninversion of the sign of the photocurrent and transition to its superlinear\ndependence on the intensity. The photoconductivity also shows a superlinear\nraise with the intensity. We show that the observed photoresponse\nnonlinearities are caused by the band-to-band \\emph{light} impact ionization\nunder conditions of a photon energy less than the forbidden gap. The signature\nof this kind of impact ionization is that the angular radiation frequency\n$\\omega=2\\pi f$ is much higher than the reciprocal momentum relaxation time.\nThus, the impact ionization takes place solely because of collisions in the\npresence of a high-frequency electric field. The effect has been measured on\nnarrow HgTe/CdTe QWs of 5.7\\,nm width; the nonlinearity is detected for\nlinearly and circularly polarized THz radiation with different frequencies\nranging from $f=0.6$ to 1.07\\,THz and intensities up to hundreds of kW/cm$^2$.\nWe demonstrate that the probability of the impact ionization is proportional to\nthe exponential function, $\\exp(-E_0^2/E^2)$, of the radiation electric field\namplitude $E$ and the characteristic field parameter $E_0$. The effect is\nobservable in a wide temperature range from 4.2 to 90\\,K, with the\ncharacteristic field increasing with rising temperature."
    },
    {
        "anchor": "Hyperfine effects in quantum wires: This paper has been removed.",
        "positive": "Nanomechanical vibrational response from electrical mixing measurements: Driven nanomechanical resonators based on low-dimensional materials are\nroutinely and efficiently detected with electrical mixing measurements.\nHowever, the measured signal is a non-trivial combination of the mechanical\neigenmode displacement and an electrical contribution, which makes the\nextraction of the driven mechanical response challenging. Here, we report a\nsimple yet reliable method to extract solely the driven mechanical vibrations\nby eliminating the contribution of pure electrical origin. This enables us to\nmeasure the spectral mechanical response as well as the driven quadratures of\nmotion. We further show how to calibrate the measured signal into units of\ndisplacement. Additionally, we utilize the pure electrical contribution to\ndirectly determine the effective mass of the measured mechanical mode. Our\nmethod marks a key step forward in the study of nanoelectromechanical\nresonators based on low-dimensional materials in both the linear and the\nnonlinear regime."
    },
    {
        "anchor": "Phonon-pump XUV-photoemission-probe in graphene: evidence for\n  non-adiabatic heating of Dirac carriers by lattice deformation: We modulate the atomic structure of bilayer graphene by driving its lattice\nat resonance with the in-plane E1u lattice vibration at 6.3um. Using time- and\nangle-resolved photoemission spectroscopy (tr-ARPES) with extreme ultra-violet\n(XUV) pulses, we measure the response of the Dirac electrons near the K-point.\nWe observe that lattice modulation causes anomalous carrier dynamics, with the\nDirac electrons reaching lower peak temperatures and relaxing at faster rate\ncompared to when the excitation is applied away from the phonon resonance or in\nmonolayer samples. Frozen phonon calculations predict dramatic band structure\nchanges when the E1u vibration is driven, which we use to explain the anomalous\ndynamics observed in the experiment.",
        "positive": "Correlation Effects in Wave Function Mapping of Molecular Beam Epitaxy\n  Grown Quantum Dots: We investigate correlation effects in the regime of a few electrons in\nuncapped InAs quantum dots by tunneling spectroscopy and wave function (WF)\nmapping at high tunneling currents where electron-electron interactions become\nrelevant. Four clearly resolved states are found, whose approximate symmetries\nare roughly s and p, in order of increasing energy. Because the major axes of\nthe p-like states coincide, the WF sequence is inconsistent with the imaging of\nindependent-electron orbitals. The results are explained in terms of many-body\ntunneling theory, by comparing measured maps with those calculated by taking\ncorrelation effects into account."
    },
    {
        "anchor": "Gate tunable third-order nonlinear optical response of massless Dirac\n  fermions in graphene: Materials with massless Dirac fermions can possess exceptionally strong and\nwidely tunable optical nonlinearities. Experiments on graphene monolayer have\nindeed found very large third-order nonlinear responses, but the reported\nvariation of the nonlinear optical coefficient by orders of magnitude is not\nyet understood. A large part of the difficulty is the lack of information on\nhow doping or chemical potential affects the different nonlinear optical\nprocesses. Here we report the first experimental study, in corroboration with\ntheory, on third harmonic generation (THG) and four-wave mixing (FWM) in\ngraphene that has its chemical potential tuned by ion-gel gating. THG was seen\nto have enhanced by ~30 times when pristine graphene was heavily doped, while\ndifference-frequency FWM appeared just the opposite. The latter was found to\nhave a strong divergence toward degenerate FWM in undoped graphene, leading to\na giant third-order nonlinearity. These truly amazing characteristics of\ngraphene come from the possibility to gate-control the chemical potential,\nwhich selectively switches on and off one- and multi-photon resonant\ntransitions that coherently contribute to the optical nonlinearity, and\ntherefore can be utilized to develop graphene-based nonlinear optoelectronic\ndevices.",
        "positive": "Landau-Zener transitions in a linear chain: We present an exact asymptotic solution for electron transition amplitudes in\nan infinite linear chain driven by an external homogeneous time-dependent\nelectric field. This solution extends the Landau-Zener theory for the case of\ninfinite number of states in discrete spectrum. In addition to transition\namplitudes we calculate an effective diffusion constant."
    },
    {
        "anchor": "Continuous monitoring of a trapped, superconducting spin: Readout and control of fermionic spins in solid-state systems are key\nprimitives of quantum information processing and microscopic magnetic sensing.\nThe highly localized nature of most fermionic spins decouples them from\nparasitic degrees of freedom, but makes long-range interoperability difficult\nto achieve. In light of this challenge, an active effort is underway to\nintegrate fermionic spins with circuit quantum electrodynamics (cQED), which\nwas originally developed in the field of superconducting qubits to achieve\nsingle-shot, quantum-non-demolition (QND) measurements and long-range\ncouplings. However, single-shot readout of an individual spin with cQED has\nremained elusive due to the difficulty of coupling a resonator to a particle\ntrapped by a charge-confining potential. Here we demonstrate the first\nsingle-shot, cQED readout of a single spin. In our novel implementation, the\nspin is that of an individual superconducting quasiparticle trapped in the\nAndreev levels of a semiconductor nanowire Josephson element. Due to a\nspin-orbit interaction inside the nanowire, this \"superconducting spin\"\ndirectly determines the flow of supercurrent through the element. We harnessed\nthis spin-dependent supercurrent to achieve both a zero-field spin splitting as\nwell as a long-range interaction between the quasiparticle and a\nsuperconducting microwave resonator. Owing to the strength of this interaction\nin our device, measuring the resultant spin-dependent resonator frequency\nyielded QND spin readout with 92% fidelity in 1.9 $\\mu$s and allowed us to\nmonitor the quasiparticle's spin in real time. These results pave the way for\nnew \"fermionic cQED\" devices: superconducting spin qubits operating at zero\nmagnetic field, devices in which the spin has enhanced governance over the\ncircuit, and time-domain measurements of Majorana modes.",
        "positive": "Tunable Capacitor For Superconducting Qubits Using an InAs/InGaAs\n  Heterostructure: Adoption of fast, parametric coupling elements has improved the performance\nof superconducting qubits, enabling recent demonstrations of quantum advantage\nin randomized sampling problems. The development of low loss, high contrast\ncouplers is critical for scaling up these systems. We present a blueprint for a\ngate-tunable coupler realized with a two-dimensional electron gas in an\nInAs/InGaAs heterostructure. Rigorous numerical simulations of the\nsemiconductor and high frequency electromagnetic behavior of the coupler and\nmicrowave circuitry yield an on/off ratio of more than one order of magnitude.\nWe give an estimate of the dielectric-limited loss from the inclusion of the\ncoupler in a two qubit system, with coupler coherences ranging from a few to\ntens of microseconds."
    },
    {
        "anchor": "Dichotomous Dynamics of Magnetic Monopole Fluids: A recent advance in the study of emergent magnetic monopoles was the\ndiscovery that monopole motion is restricted to dynamical fractal trajectories\n(J. Hall\\'en et al, Science 378, 1218 (2022)) thus explaining the\ncharacteristics of magnetic monopole noise spectra (Dusad, R. et al. Nature\n571, 234 (2019); Samarakoon, A. M. et al. Proc. Natl. Acad. Sci. 119,\ne2117453119 (2022)). Here we apply this new theory to explore the dynamics of\nfield-driven monopole currents, finding them comprised of two quite distinct\ntransport processes: initially swift fractal rearrangements of local monopole\nconfigurations followed by conventional monopole diffusion. This theory also\npredicts a characteristic frequency dependence of the dissipative loss-angle\nfor AC-field-driven currents. To explore these novel perspectives on monopole\ntransport, we introduce simultaneous monopole current control and measurement\ntechniques using SQUID-based monopole current sensors. For the canonical\nmaterial Dy2Ti2O7, we measure ${\\Phi}(t)$, the time-dependence of magnetic flux\nthreading the sample when a net monopole current $J(t) = \\dot{\\Phi}(t)/\\mu_0$\nis generated by applying an external magnetic field $B_0(t)$. These experiments\nfind a sharp dichotomy of monopole currents, separated by their distinct\nrelaxation time-constants before and after $t \\approx 600 {\\mu}s$ from monopole\ncurrent initiation. Application of sinusoidal magnetic fields $B_0(t) =\nBcos({\\omega}t)$ generates oscillating monopole currents whose loss angle\n${\\theta}(f)$ exhibits a characteristic transition at frequency $f \\approx 1.8$\nkHz over the same temperature range. Finally, the magnetic noise power is also\ndichotomic, diminishing sharply after $t \\approx 600 {\\mu}s$. This complex\nphenomenology represents a new form of heterogeneous dynamics generated by the\ninterplay of fractionalization and local spin configurational symmetry.",
        "positive": "Bound States in a Quantized Hall Ferromagnet: We report on a study of the quasielectron-quasihole and skyrmion-antiskyrmion\nbound states in the $\\nu=1$ quantum Hall regime. The short range attraction\npotential is assumed to be determined by a point magnetic impurity. The\ncalculations are performed within the strong field approximation when the\nbinding energy and the characteristic electron-electron interaction energy are\nsmaller than the Landau level spacing. The Excitonic Representation technique\nis used in that case."
    },
    {
        "anchor": "Black phosphorus: A new bandgap tuning knob: Modern electronics rely on devices whose functionality can be adjusted by the\nend-user with an external 'knob'. A new tuning knob to modify the band gap of\nblack phosphorus has been experimentally demonstrated.",
        "positive": "Diamond quantum thermometry: From foundations to applications: Diamond quantum thermometry exploits the optical and electrical spin\nproperties of colour defect centres in diamonds and, acts as a quantum sensing\nmethod exhibiting ultrahigh precision and robustness. Compared to the existing\nluminescent nanothermometry techniques, a diamond quantum thermometer can be\noperated over a wide temperature range and a sensor spatial scale ranging from\nnanometres to micrometres. Further, diamond quantum thermometry is employed in\nseveral application, including electronics and biology, to explore these fields\nwith nanoscale temperature measurements. This review covers the operational\nprinciples of diamond quantum thermometry for spin-based and all-optical\nmethods, material development of diamonds with a focus on thermometry, and\nexamples of applications in electrical and biological systems with demand-based\ntechnological requirements."
    },
    {
        "anchor": "Including many-body effects into the Wannier-interpolated quadratic\n  photoresponse tensor: We present a first-principles scheme for incorporating many-body interactions\ninto the unified description of the quadratic optical response to light of\nnoncentrosymmetric crystals. The proposed method is based on time-dependent\ncurrent-density response theory and includes the electron-hole attraction\n\\textit{via} a tensorial long-range exchange-correlation kernel, which we\ncalculate self-consistently using the bootstrap method. By bridging with the\nWannier-interpolation of the independent-particle transition matrix elements,\nthe resulting numerical scheme is very general and allows resolving narrow\nmany-body spectral features at low computational cost. We showcase its\npotential by inspecting the second-harmonic generation in the benchmark\nzinc-blende semiconductor GaAs, the layered graphitic semiconductor BC$_{2}$N\nand the Weyl semimetal TaAs. Our results show that excitonic effects can give\nrise to large and sharply localized one- and two-photon resonances that are\nabsent in the independent-particle approximation. We find overall good\nagreement with available experimental measurements, capturing the magnitude and\npeak-structure of the spectrum as well as the angular dependence at fixed\nphoton energy. The implementation of the method in Wannier-based code packages\ncan serve as a basis for performing accurate theoretical predictions of\nquadratic optical properties in a vast pool of materials.",
        "positive": "Impurity States in Graphene: Defects in graphene are of crucial importance for its electronic and magnetic\nproperties. Here impurity effects on the electronic structure of surrounding\ncarbon atoms are considered and the distribution of the local densities of\nstates (LDOS) is calculated. As the full range from near field to the\nasymptotic regime is covered, our results are directly accessible by scanning\ntunnelling microscopy (STM). We also include exchange scattering at magnetic\nimpurities and eludicate how strongly spin polarized impurity states arise."
    },
    {
        "anchor": "Anisotropic quantum transport in monolayer graphene in the presence of\n  Rashba spin-orbit coupling: We have studied spin-depend electron tunnelling through the Rashba barrier in\na monolayer graphene lattice. The transfer matrix method, have been employed to\nobtain the spin dependent transport properties of the chiral particles. It is\nshown that graphene sheets in presence of Rashba spin-orbit barrier will act as\nan electron spin- inverter.",
        "positive": "Quantum Kinetic Equation for the Wigner Equation and Reduction to the\n  Boltzmann Transport Equation under Discrete Impurities: We drive a quantum kinetic equation under discrete impurities for the Wigner\nfunction from the quantum Liouville equation. To attain this goal, the\nelectrostatic Coulomb potential is separated into the long- and short-range\nparts, and the self-consistent coupling with Poisson's equation is explicitly\ntaken into account. It is shown that the collision integral associated with\nimpurity scattering as well as the usual drift term is derived on an equal\nfooting and that the conventional treatment of impurity scattering under the\nWigner function scheme is inconsistent in the sense that the collision integral\nis introduced in an ad hoc way and, thus, the short-range part of the impurity\npotential is double-counted. The Boltzmann transport equation (BTE) is derived\nwithout imposing an assumption of random impurity configurations over the\nsubstrate. The derived BTE is able to describe the discrete nature of\nimpurities such as potential fluctuations and, thus, appropriate to analyze\nelectron transport under semiconductor nanostructures."
    },
    {
        "anchor": "Composite fermion theory of correlated electrons in semiconductor\n  quantum dots in high magnetic fields: Interacting electrons in a semiconductor quantum dot at strong magnetic\nfields exhibit a rich set of states, including correlated quantum fluids and\ncrystallites of various symmetries. We develop in this paper a perturbative\nscheme based on the correlated basis functions of the composite-fermion theory,\nthat allows a systematic improvement of the wave functions and the energies for\nlow-lying eigenstates. For a test of the method, we study systems for which\nexact results are known, and find that practically exact answers are obtained\nfor the ground state wave function, ground state energy, excitation gap, and\nthe pair correlation function. We show how the perturbative scheme helps\nresolve the subtle physics of competing orders in certain anomalous cases.",
        "positive": "The effects of Mn concentration on spin-polarized transport through\n  ZnSe/ZnMnSe/ZnSe heterostructures: We have studied the effects of Mn concentration on the ballistic\nspin-polarized transport through diluted magnetic semiconductor\nheterostructures with a single paramagnetic layer. Using a fitted function for\nzero-field conduction band offset based on the experimental data, we found that\nthe spin current densities strongly depend on the Mn concentration. The\nmagnitude as well as the sign of the electron-spin polarization and the tunnel\nmagnetoresistance can be tuned by varying the Mn concentration, the width of\nthe paramagnetic layer, and the external magnetic field. By an appropriate\nchoice of the Mn concentration and the width of the paramagnetic layer, the\ndegree of spin polarization for the output current can reach 100% and the\ndevice can be used as a spin filter."
    },
    {
        "anchor": "Testing the Landau Fermi liquid description of the fractional quantum\n  Hall effect: We study theoretically the dispersion of a single quasiparticle or quasihole\nof the fractional quantum Hall effect, obtained by injecting or removing a\ncomposite fermion. By comparing to a free fermion system, we estimate the\nregime of validity of the Landau-Fermi-liquid-type description and deduce the\nLandau mass.",
        "positive": "Electrical spin injection and accumulation in CoFe/MgO/Ge contacts at\n  room temperature: We first report the all-electrical spin injection and detection in\nCoFe/MgO/moderately doped n-Ge contact at room temperature (RT), employing\nthreeterminal Hanle measurements. A sizable spin signal of ~170 k{\\Omega}\n{\\mu}m^2 has been observed at RT, and the analysis using a single-step\ntunneling model gives a spin lifetime of ~120 ps and a spin diffusion length of\n~683 nm in Ge. The observed spin signal shows asymmetric bias and temperature\ndependences which are strongly related to the asymmetry of the tunneling\nprocess."
    },
    {
        "anchor": "Back-action Induced Non-equilibrium Effect in Electron Charge Counting\n  Statistics: We report our study of the real-time charge counting statistics measured by a\nquantum point contact (QPC) coupled to a single quantum dot (QD) under\ndifferent back-action strength. By tuning the QD-QPC coupling or QPC bias, we\ncontrolled the QPC back-action which drives the QD electrons out of thermal\nequilibrium. The random telegraph signal (RTS) statistics showed strong and\ntunable non-thermal-equilibrium saturation effect, which can be quantitatively\ncharacterized as a back-action induced tunneling out rate. We found that the\nQD-QPC coupling and QPC bias voltage played different roles on the back-action\nstrength and cut-off energy.",
        "positive": "Ultrafast Momentum-resolved Hot Electron Dynamics in the Two-dimensional\n  Topological Insulator Bismuthene: Two-dimensional quantum spin Hall (QSH) insulators are a promising material\nclass for spintronic applications based on topologically-protected spin\ncurrents in their edges. Yet, they have not lived up to their technological\npotential, as experimental realizations are scarce and limited to cryogenic\ntemperatures. These constraints have also severely restricted characterization\nof their dynamical properties. Here, we report on the electron dynamics of the\nnovel room-temperature QSH candidate bismuthene after photoexcitation using\ntime- and angle-resolved photoemission spectroscopy. We map the transiently\noccupied conduction band and track the full relaxation pathway of hot\nphotocarriers. Intriguingly, we observe photocarrier lifetimes much shorter\nthan in \\red{conventional} semiconductors. This is ascribed to the presence of\ntopological in-gap states already established by local probes. Indeed, we find\nspectral signatures consistent with these earlier findings. Demonstration of\nthe large band gap and the view into photoelectron dynamics mark a critical\nstep toward optical control of QSH functionalities."
    },
    {
        "anchor": "Fine structure of an exciton coupled to a single Fe2+ ion in a CdSe/ZnSe\n  quantum dot: We present a polarization-resolved photoluminescence study of the exchange\ninteraction effects in a prototype system consisting of an individual Fe2+ ion\nand a single neutral exciton confined in a CdSe/ZnSe quantum dot. Maximal\npossible number of eight fully linearly-polarized lines in the bright exciton\nemission spectrum is observed, evidencing complete degeneracy lifting in the\ninvestigated system. We discuss conditions required for such a scenario to take\nplace: anisotropy of the electron-hole interaction and the zero-field splitting\nof the Fe2+ ion spin states. Neglecting of either of these components is shown\nto restore partial degeneracy of the transitions, making the excitonic spectrum\nsimilar to those previously reported for all other systems of quantum dots with\nsingle magnetic dopants.",
        "positive": "Retardation of entanglement decay of two spin qubits by quantum\n  measurements: We study a system of two electron spins each interacting with its small\nnuclear spin environment (NSE), which is a prototype system of two electron\nspin quantum dot (QD) qubits. We propose a way to counteract the decay of\nentanglement in two-electron spin subsystem (TESSS) by performing some\nmanipulations on TESSS (the subsystem to which experimentalists have an\naccess), e.g. repeatable quantum projective measurements of TESSS. Unlike in\nthe quantum Zeno effect, the goal of the proposed manipulations is not to\nfreeze TESSS in its initial state and to preclude any time evolution of the\nstate by infinitely frequent quantum measurements. Instead of that, performing\na few cycles of free evolution of the system for some time $\\tau$ followed by a\nquantum measurement of TESSS with subsequent postselection of TESSS state (the\nsame as the initial one) produces quantum correlations in NSEs and also\nrestores the quantum correlations in TESSS. By numerical calculation of the\nsystem evolution (the full density matrix $\\hat \\rho(t)$), we show that, in\ncontrast to the fast decay of TESSS entanglement on timescale of the order of\n$T_2^*$, application of the proposed manipulation sequence gradually builds up\ncoherences in the entire system and the rest decay of quantum correlations of\nTESSS may be significantly slowed down for specific cycle durations $\\tau$ and\nnumbers of performed cycles."
    },
    {
        "anchor": "Dirac Hamiltonians for bosonic spectra: Dirac materials are of great interest as condensed matter realizations of the\nDirac and Weyl equations. In particular, they serve as a starting point for the\nstudy of topological phases. This physics has been extensively studied in\nelectronic systems such as graphene, Weyl- and Dirac semi-metals. In contrast,\nrecent studies have highlighted several examples of Dirac-like cones in\ncollective excitation spectra, viz. in phonon, magnon and triplon bands. These\ncannot be directly related to the Dirac or Weyl equations as they are bosonic\nin nature with pseudo-unitary band bases. In this article, we show that any\nDirac-like equation can be smoothly deformed into a form that is applicable to\nbosonic bands. The resulting bosonic spectra bear a two-to-one relation to that\nof the parent Dirac system. Their dispersions inherit several interesting\nproperties including conical band touching points and a gap-opening-role for\n`mass' terms. The relationship also extends to the band eigenvectors with the\nbosonic states carrying the same Berry connections as the parent fermionic\nstates. The bosonic bands thus inherit topological character as well. If the\nparent fermionic system has non-trivial topology that leads to mid-gap surface\nstates, the bosonic analogue also hosts surface states that lie within the\ncorresponding band gap. The proposed bosonic Dirac structure appears in several\nknown models. In materials, it is realized in Ba$_2$CuSi$_2$O$_6$Cl$_2$ and\npossibly in CoTiO$_3$ as well as in paramagnetic honeycomb ruthenates. Our\nresults allow for a rigorous understanding of Dirac phononic and magnonic\nsystems and enable concrete predictions, e.g., of surface states in magnonic\ntopological insulators and Weyl semi-metals.",
        "positive": "1500-fold Tunneling Anisotropic Magnetoresistance in a (Ga,Mn)As stack: We report the discovery of a super-giant tunneling anisotropic\nmagnetoresistance in an epitaxially grown (Ga,Mn)As/GaAs/(Ga,Mn)As structure.\nThe effect arises from a strong dependence of the electronic structure of\nferromagnetic semiconductors on the magnetization orientation rather than from\na parallel or antiparallel alignment of the contacts. The key novel spintronics\nfeatures of this effect are: (i) both normal and inverted spin-valve like\nsignals; (ii) a large non-hysteretic magnetoresistance for magnetic fields\nperpendicular to the interfaces; (iii) magnetization orientations for extremal\nresistance are, in general, not aligned with the magnetic easy and hard axis.\n(iv) Enormous amplification of the effect at low bias and temperatures."
    },
    {
        "anchor": "Shot-noise anomalies in nondegenerate elastic diffusive conductors: We present a theoretical investigation of shot-noise properties in\nnondegenerate elastic diffusive conductors. Both Monte Carlo simulations and\nanalytical approaches are used. Two new phenomena are found: (i) the display of\nenhanced shot noise for given energy dependences of the scattering time, and\n(ii) the recovery of full shot noise for asymptotic high applied bias. The\nfirst phenomenon is associated with the onset of negative differential\nconductivity in energy space that drives the system towards a dynamical\nelectrical instability in excellent agreement with analytical predictions. The\nenhancement is found to be strongly amplified when the dimensionality in\nmomentum space is lowered from 3 to 2 dimensions. The second phenomenon is due\nto the suppression of the effects of long range Coulomb correlations that takes\nplace when the transit time becomes the shortest time scale in the system, and\nis common to both elastic and inelastic nondegenerate diffusive conductors.\nThese phenomena shed new light in the understanding of the anomalous behavior\nof shot noise in mesoscopic conductors, which is a signature of correlations\namong different current pulses.",
        "positive": "Periodic magnetic structures generated by spin-polarized currents in\n  nanostripes: The influence of a spin-polarized current on long ferromagnetic nanostripes\nis studied numerically. The current flows perpendicularly to the stripe. The\nstudy is based on the Landau-Lifshitz phenomenological equation with the\nSlonczewski-Berger spin-torque term. The magnetization behavior is analyzed for\nall range of the applied currents, up to the saturation. It is shown that the\nsaturation current is a nonmonotonic function of the stripe width. For a stripe\nwidth increasing it approaches the saturation value for an infinite film. A\nnumber of stable periodic magnetization structures are observed below the\nsaturation. Type of the periodical structure depends on the stripe width.\nBesides the one-dimensional domain structure, typical for narrow wires, and the\ntwo-dimensional vortex-antivortex lattice, typical for wide films, a number of\nintermediate structures are observed, e.g. cross-tie and diamond state. For\nnarrow stripes an analytical analysis is provided."
    },
    {
        "anchor": "Global Equilibrium and Non-Equilibrium Theory of Hopping Exciton\n  Transport in Disordered Semiconductors: We develop a temperature dependent theory for singlet exciton hopping\ntransport in disordered semiconductors. It draws on the transport level concept\nwithin a F\\\"orster transfer model and bridges the gap in describing the\ntransition from equilibrium to non-equilibrium time dependent spectral\ndiffusion. We test the validity range of the developed model using kinetic\nMonte Carlo simulations and find agreement over a broad range of temperatures.\nIt reproduces the scaling of the diffusion length and spectral shift with the\ndimensionless disorder parameter and describes in a unified manner the\ntransition from equilibrium to non-equilibrium transport regime. We find that\nthe diffusion length in the non-equilibrium regime does not scale with the the\nthird power of the F\\\"orster radius. The developed theory provides a powerful\ntool for interpreting time-resolved and steady state spectroscopy experiments\nin a variety of disordered materials, including organic semiconductors and\ncolloidal quantum dots.",
        "positive": "Slow steady flow of a skyrmion lattice in a confined geometry probed by\n  resistance narrow-band noise: Using resistance fluctuation spectroscopy, we observe current-induced\nnarrow-band noise (NBN) in the magnetic skyrmion-lattice phase of\nmicrometer-sized MnSi. The NBN appears only when electric-current density\nexceeds a threshold value, indicating that the current-driven motion of the\nskyrmion lattice triggers the NBN. The observed NBN frequency is 10-10$^4$ Hz\nat $\\sim$10$^{9}$ A/m$^{2}$, implying a skyrmion steady flow velocity of 1-100\n$\\mu$m/s, 3-5 orders of magnitude slower than previously reported. The\ntemperature evolution of the NBN frequency suggests that the steady flow\nentails thermally activated processes, which are most likely due to skyrmion\ncreation and annihilation at the sample edges. This scenario is qualitatively\nsupported by our numerical simulations considering boundary effects, which\nreveals that the edges limit the steady flow of skyrmions, especially at low\ntemperatures. We discuss a mechanism that dramatically slows the skyrmion\nsteady flow in a microfabricated specimen."
    },
    {
        "anchor": "Current driven second harmonic domain wall resonance in ferromagnetic\n  metal/ nonmagnetic metal bilayer: a field-free method for spin Hall angle\n  measurements: We study the ac current-driven domain wall motion in bilayer ferromagnetic\nmetal (FM)/nonmagnetic metal (NM) nanowire. The solution of the modified\nLandau-Lifshitz-Gilbert equation including all the spin transfer torques is\nused to describe motion of the domain wall in presence of the spin Hall effect.\nWe show that the domain wall center has second harmonic frequency response in\naddition to the known first harmonic excitation. In contrast to the\nexperimentally observed second harmonic response in harmonic Hall measurements\nof spin-orbit torque in magnetic thin films, this second harmonic response\ndirectly originates from spin-orbit torque driven domain wall dynamics. Based\non the spin current generated by domain wall dynamics, the longitudinal spin\nmotive force generated voltage across the length of the nanowire is determined.\nThe second harmonic response introduces additionally a new practical field-free\nand all-electrical method to probe the effective spin Hall angle for FM/NM\nbilayer structures that could be applied in experiments. Our results also\ndemonstrate the capability of utilizing FM/NM bilayer structure in domain wall\nbased spin torque signal generators and resonators.",
        "positive": "Residual bulk viscosity of a disordered 2D electron gas: The nonzero bulk viscosity signals breaking of the scale invariance. We\ndemonstrate that a disorder in two-dimensional noninteracting electron gas in a\nperpendicular magnetic field results in the nonzero disorder-averaged bulk\nviscosity. We derive analytic expression for the bulk viscosity within the\nself-consistent Born approximation. This residual bulk viscosity provides the\nlower bound for the bulk viscosity of 2D interacting electrons at low enough\ntemperatures."
    },
    {
        "anchor": "A Josephson frequency for fractionally charged anyons: Anyons occur in two-dimensional electron systems as excitations with\nfractional charge in the topologically ordered states of the Fractional Quantum\nHall Effect (FQHE). Their dynamics are of utmost importance for topological\nquantum phases and possible decoherence free quantum information approaches,\nbut observing these dynamics experimentally is challenging. Here we report on a\ndynamical property of anyons: the long predicted Josephson relation fJ=e*V/h\nfor charges e*=e/3 and e/5, where e is the charge of the electron and h is\nPlanck's constant. The relation manifests itself as marked signatures in the\ndependence of Photo Assisted Shot Noise (PASN) on voltage V when irradiating\ncontacts at microwaves frequency fJ. The validation of FQHE PASN models\nindicates a path towards realizing time-resolved anyon sources based on\nlevitons.",
        "positive": "Impedance-matched High-overtone Bulk Acoustic Resonator: A high-overtone bulk acoustic resonator (HBAR), in which a piezoelectric\ntransducer is set on an acoustic cavity, has been attracting attention in both\nfundamental research and RF applications due to its scalability, high\nfrequency, and high quality factor. The acoustic impedance matching in HBARs is\ncrucial for efficient acoustic power transfer from the piezoelectric transducer\nto the cavity. However, impedance mismatch remains in most HBARs due to the\nmetal layer insertion between the piezoelectric layer and cavity substrate. In\nthis study, we fabricated a nearly impedance-matched high-quality HBAR using an\nepitaxial AlN piezoelectric layer directly grown on a conductive SiC cavity\nsubstrate with no metal layer insertion. The small impedance mismatch was\nverified from the variation in the free spectral range (FSR), which is\ncomparable to the best value in previously reported HBARs. The experimentally\nobtained FSR spectra was greatly reproduced by using the Mason model. Broadband\nphonon cavity modes up to the K-band (26.5 GHz) were achieved by reducing the\nthickness of the AlN layer from 800 to 200 nm. The high figure of merit of\n$f\\times\\text{Q} \\sim 1.3\\times 10^{13}\\ \\textrm{Hz}$ at 10 GHz was also\nobtained. Our nearly impedance-matched high-quality HBAR will enable the\ndevelopment of RF applications, such as low-phase noise oscillators and\nacoustic filters, as well as research on high-frequency acoustic systems\nhybridized with electric, optical, and magnetic systems."
    },
    {
        "anchor": "Surface optical phonon scattering in N-polar GaN quantum well channels: N-polar GaN channel mobility is important for high frequency device\napplications. In this Letter, we report the theoretical calculations on the\nsurface optical (SO) phonon scattering rate of two-dimensional electron gas\n(2-DEG) in N-polar GaN quantum well channels with high-k dielectrics. The\neffect of SO phonons on 2-DEG mobility was found to be small at >5 nm channel\nthickness. However, the SO mobility in 3 nm N-polar GaN channels with high-k\ndielectrics is low and limits the total mobility. The SO scattering for SiNx\ndielectric GaN was found to be negligible due to its high SO phonon energy.",
        "positive": "Two-component nonlinear wave of the cubic Boussinesq equation: In this work, we employ the generalized perturbation reduction method to find\nthe two-component vector breather solution of the cubic Boussinesq equation\n$U_{tt} - C U_{zz} - D U_{zzzz}+G (U^{3})_{zz}=0$. Explicit analytical\nexpressions for the shape and parameters of the two-component nonlinear pulse\noscillating with the sum and difference of the frequencies and wave numbers are\nobtained."
    },
    {
        "anchor": "Thermodynamic reciprocity in scanning photocurrent maps: Scanning photocurrent maps in inhomogeneous materials contain nontrivial\npatterns, which often can only be understood with a full model of device\ngeometry and nonuniformities. We remark on the consequences of Onsager\nreciprocity to the photocurrent in linear response, with immediate applications\nin photovoltaic and photothermoelectric effects. In particular with\nphotothermoelectric effects, we find that the ampere-per-watt responsivity is\nexactly governed by Peltier-induced temperature shifts in the same device when\ntime-reversed and voltage-biased. We show, with the example of graphene, that\nthis principle aids in understanding and modelling of photocurrent maps.",
        "positive": "Gate-induced magneto-oscillation phase anomalies in graphene bilayers: The magneto-oscillations in graphene bilayers are studied in the vicinity of\nthe K and K' points of the Brillouin zone within the four-band continuum model\nased on the simplest tight-binding approximation involving only the nearest\nneighbor interactions. The model is employed to construct Landau plots for a\nvariety of carrier concentrations and bias strengths between the graphene\nplanes. The quantum-mechanical and quasiclassical approaches are compared. We\nfound that the quantum magneto-oscillations are only asymptotically periodic\nand reach the frequencies predicted quasiclassically for high indices of Landau\nlevels. In unbiased bilayers the phase of oscillations is equal to the phase of\nmassive fermions. Anomalous behavior of oscillation phases was found in biased\nbilayers with broken inversion symmetry. The oscillation frequencies again tend\nto quasiclassically predicted ones, which are the same for $K$ and $K'$, but\nthe quantum approach yields the gate-tunable corrections to oscillation phases,\nwhich differ in sign for K and K'. These valley-dependent phase corrections\ngive rise, instead of a single quasiclassical series of oscillations, to two\nseries with the same frequency but shifted in phase."
    },
    {
        "anchor": "Oscillations in electron transport caused by multiple resonances in a\n  quantum dot-QED system in the steady-state regime: We model the electron transport current as the photon energy is swept through\nseveral resonances of a multi-level quantum dot, embedded in a short quantum\nwire, coupled to photon cavity. We use a Markovian quantum master equation\nappropriate for the long-time evolution and include the electron-electron and\nboth the para- and the diamagnetic electron-photon interactions via\ndiagonalization in a truncated many-body Fock space. Tuning the photon energy,\nseveral anti-crossings caused by Rabi-splitting in the energy spectrum of the\nquantum dot system are found. The strength of the Rabi-splittings and the\nphoton-exchange between the resonant states depend on the polarization of the\ncavity photon field. We observe oscillations of the charge in the system and\nseveral resonant transport current peaks for the photon energies corresponding\nto the resonances in the steady-state regime.",
        "positive": "Reduced Exchange Interactions in Magnetic Tunnel Junction Free Layers\n  with Insertion Layers: Perpendicularly magnetized CoFeB layers with ultra-thin non-magnetic\ninsertion layers are very widely used as the electrodes in magnetic tunnel\njunctions for spin transfer magnetic random access memory devices. Exchange\ninteractions play a critical role in determining the thermal stability of\nmagnetic states in such devices and their spin torque switching efficiency.\nHere the exchange constant of free layers incorporated in full magnetic tunnel\njunction layer stacks, specifically CoFeB free layers with W insertion layers\nis determined by magnetization measurements in a broad temperature range. A\nsignificant finding is that the exchange constant decreases significantly and\nabruptly with W insertion layer thickness. The perpendicular magnetic\nanisotropy shows the opposite trend; it initially increases with W insertion\nlayer thickness and shows a broad maximum for approximately one monolayer (0.3\nnm) of W. These results highlight the interdependencies of magnetic\ncharacteristics required to optimize the performance of magnetic tunnel\njunction devices."
    },
    {
        "anchor": "Classical absorption in small metal particles and thin films: We study the electric dipole absorption in small metal particles and thin\nfilms in a longitudnal electric field. In diffusive approximation, we give both\nthe phenomenological and microscopic derivations with the account for\nThomas-Fermi screening and Drude relaxation.",
        "positive": "Fluctuations and photon statistics in quantum metamaterial near the\n  superradiant transition: The analysis of single-mode photon fluctuations and their counting statistics\nat the superradiant phase transition is presented. The study concerns the\nequilibrium Dicke model in a regime where the Rabi frequency, related to a\ncoupling of the photon mode with a finite-number qubit environment, plays a\nrole of the transition's control parameter. We use the effective Matsubara\naction formalism based on the representation of Pauli operators as bilinear\nforms with complex and Majorana fermions. Then, we address fluctuations of\nsuperradiant order parameter and quasiparticles. The average photon number, the\nfluctuational Ginzburg-Levanyuk region of the phase transition and Fano factor\nare evaluated. We determine the cumulant generating function which describes a\nfull counting statistics of equilibrium photon number. Exact numerical\nsimulation of the superradiant transition demonstrates quantitative agreement\nwith analytical calculations."
    },
    {
        "anchor": "On-chip excitation of single germanium-vacancies in nanodiamonds\n  embedded in plasmonic waveguides: Monolithic integration of quantum emitters in nanoscale plasmonic circuitry\nrequires low-loss plasmonic configurations capable of confining light well\nbelow the diffraction limit. We demonstrate on-chip remote excitation of\nnanodiamond-embedded single quantum emitters by plasmonic modes of dielectric\nridges atop colloidal silver crystals. The nanodiamonds are produced to\nincorporate single germanium-vacancy (GeV) centers, providing bright,\nspectrally narrow and stable single-photon sources suitable for highly\nintegrated circuits. Using electron-beam lithography with hydrogen\nsilsesquioxane (HSQ) resist, dielectric-loaded surface plasmon polariton\nwaveguides (DLSPPWs) are fabricated on single crystalline silver plates so as\nto contain those of spin-casted nanodiamonds that are found to feature\nappropriate single GeV centers. The low-loss plasmonic configuration enabled\nthe 532 nm pump laser light to propagate on-chip in the DLSPPW and reach to an\nembedded nanodiamond where a single GeV center is incorporated. The remote GeV\nemitter is thereby excited and coupled to spatially confined DLSPPW modes with\nan outstanding figure-of-merit of 180 due to a ~6-fold Purcell enhancement,\n~56% coupling efficiency and ~33 {\\mu}m transmission length, revealing the\npotential of our approach for on-chip realization of nanoscale functional\nquantum devices.",
        "positive": "STM contrast of a CO dimer on a Cu(1 1 1) surface: a wave-function\n  analysis: We present a method used to intuitively interpret the STM contrast by\ninvestigating individual wave functions originating from the substrate and tip\nside. We use localized basis orbital density functional theory, and propagate\nthe wave functions into the vacuum region at a real-space grid, including\naveraging over the lateral reciprocal space. Optimization by means of the\nmethod of Lagrange multipliers is implemented to perform a unitary\ntransformation of the wave functions in the middle of the vacuum region. The\nmethod enables (i) reduction of the number of contributing tip-substrate wave\nfunction combinations used in the corresponding transmission matrix, and (ii)\nto bundle up wave functions with similar symmetry in the lateral plane, so that\n(iii) an intuitive understanding of the STM contrast can be achieved. The\ntheory is applied to a CO dimer adsorbed on a Cu(1 1 1) surface scanned by a\nsingle-atom Cu tip, whose STM image is discussed in detail by the outlined\nmethod."
    },
    {
        "anchor": "Inconsistency between Linearized Thomas-Fermi Approximation and\n  Electron-Ionized Impurity Scattering Rate in the first Born Approximation: We show that by computing the electron-impurity scattering rate at the first\norder via Fermi's golden rule, and assuming that the localized impurity\npotential is of Yukawa form, one obtains a wave vector transfer distribution\nwhich is inconsistent with the finite temperature linearized Thomas-Fermi\napproximation for {\\it n}-type semiconductors. Our previous findings show that\nthis is not the case for the carrier nondegenerate dynamics, because the\naverage wave vector transferred being in general negligible in this regime.\nMoreover, we examine the behavior of the electron-impurity differential\ncross-sections in the first Born approximation for relevant values of the wave\nvector transfer. We find that in the majority of collisions, the scattering\nprobabilities differ at the most by $1$ \\% from the estimates computed by means\nof the impurity potential at random phase approximation level.",
        "positive": "Entanglement Spectrum Crossings Reveal non-Hermitian Dynamical Topology: The development of non-Hermitian topological band theory has led to\nobservations of novel topological phenomena in effectively classical, driven\nand dissipative systems. However, for open quantum many-body systems, the\nabsence of a ground state presents a challenge to define robust signatures of\nnon-Hermitian topology. We show that such a signature is provided by crossings\nin the time evolution of the entanglement spectrum. These crossings occur in\nquenches from the trivial to the topological phase of a driven-dissipative\nKitaev chain that is described by a Markovian quantum master equation in\nLindblad form. At the topological transition, which can be crossed either by\nchanging parameters of the Hamiltonian of the system or by increasing the\nstrength of dissipation, the time scale at which the first entanglement\nspectrum crossing occurs diverges with a dynamical critical exponent of\n$\\epsilon = 1/2$. We corroborate these numerical findings with an exact\nanalytical solution of the quench dynamics for a spectrally flat postquench\nLiouvillian. This exact solution suggests an interpretation of the topological\nquench dynamics as a fermion parity pump. Our work thus reveals signatures of\nnon-Hermitian topology which are unique to quantum many-body systems and cannot\nbe emulated in classical simulators of non-Hermitian wave physics."
    },
    {
        "anchor": "Classical and quantum magneto-oscillations of current flow near a p-n\n  junction in graphene: The proposed semiclassical theory predicts two types of oscillations in the\nflow of current injected from a point source near a ballistic p-n junction in\ngraphene in a strong magnetic field. One originates from the classical effect\nof bunching of cyclotron orbits of electrons passing back and forth across the\np-n interface, which displays a pronounced dependence on the commensurability\nbetween the cyclotron radii in the n- and p-regions. The other effect is caused\nby the interference of monochromatic electron waves in p-n junctions with equal\ncarrier densities on the two sides and it consists in magneto-oscillations in\nthe current transmission through the interface with periodicity similar to\nShubnikov-de Haas oscillations.",
        "positive": "Electron Spectral Functions of Reconstructed Quantum Hall Edges: During the reconstruction of the edge of a quantum Hall liquid, Coulomb\ninteraction energy is lowered through the change in the structure of the edge.\nWe use theory developed earlier by one of the authors [K. Yang, Phys. Rev.\nLett. 91, 036802 (2003)] to calculate the electron spectral functions of a\nreconstructed edge, and study the consequences of the edge reconstruction for\nthe momentum-resolved tunneling into the edge. It is found that additional\nexcitation modes that appear after the reconstruction produce distinct features\nin the energy and momentum dependence of the spectral function, which can be\nused to detect the presence of edge reconstruction."
    },
    {
        "anchor": "Emergent gauge fields from curvature in single layers of\n  transition-metal dichalcogenides: We analyze the electron dynamics in corrugated layers of transition-metal\ndichalcogenides. Due to the strong spin-orbit coupling, the intrinsic\n(Gaussian) curvature leads to an emergent gauge field associated with the Berry\nconnection of the spinor wave function. We discuss the gauge field created by\ntopological defects of the lattice, namely, tetragonal/octogonal disclinations\nand edge dislocations. Ripples and topological disorder induce the same\ndephasing effects as a random magnetic field, suppressing the weak localization\neffects. This geometric magnetic field can be detected in a Aharonov-Bohm\ninterferometry experiment by measuring the local density of states in the\nvicinity of corrugations.",
        "positive": "Rhodium Nanoparticles for Ultraviolet Plasmonics: The non-oxidizing catalytic noble metal rhodium is introduced for ultraviolet\nplasmonics. Planar tripods of 8 nm Rh nanoparticles, synthesized by a modified\npolyol reduction method, have a calculated local surface plasmon resonance near\n330 nm. By attaching p-aminothiophenol, local field-enhanced Raman spectra and\naccelerated photo-damage were observed under near-resonant ultraviolet\nillumination, while charge transfer simultaneously increased fluorescence for\nup to 13 minutes. The combined local field enhancement and charge transfer\ndemonstrate essential steps toward plasmonically-enhanced ultraviolet\nphotocatalysis."
    },
    {
        "anchor": "Holographic duality between $(2+1)$-d quantum anomalous Hall state and\n  $(3+1)$-d topological insulators: In this paper, we study $(2+1)$-dimensional quantum anomalous Hall states,\ni.e. band insulators with quantized Hall conductance, using the exact\nholographic mapping. The exact holographic mapping is an approach to\nholographic duality which maps the quantum anomalous Hall state to a different\nstate living in $(3+1)$-dimensional hyperbolic space. By studying topological\nresponse properties and the entanglement spectrum, we demonstrate that the\nholographic dual theory of a quantum anomalous Hall state is a\n$(3+1)$-dimensional topological insulator. The dual description enables a new\ncharacterization of topological properties of a system by the quantum\nentanglement between degrees of freedom at different length scales.",
        "positive": "Comment on Hess et al. Phys. Rev. Lett. {\\bf 130}, 207001 (2023): In this comment, we show that the model introduced in Hess et al. Phys. Rev.\nLett. {\\bf 130}, 207001 (2023) fails the topological gap protocol (TGP)\n(Pikulin et al., arXiv:2103.12217 and M. Aghaee et al., Phys. Rev. B 107,\n245424 (2023)). In addition, we discuss this model in the broader context of\nhow the TGP has been benchmarked."
    },
    {
        "anchor": "Signatures of dark excitons in exciton-polariton optics of transition\n  metal dichalcogenides: Integrating 2D materials into high-quality optical microcavities opens the\ndoor to fascinating many-particle phenomena including the formation of\nexciton-polaritons. These are hybrid quasi-particles inheriting properties of\nboth the constituent photons and excitons. In this work, we investigate the\nso-far overlooked impact of dark excitons on the momentum-resolved absorption\nspectra of hBN-encapsulated WSe$_2$ and MoSe$_2$ monolayers in the\nstrong-coupling regime. In particular, thanks to the efficient phonon-mediated\nscattering of polaritons into energetically lower dark exciton states, the\nabsorption of the lower polariton branch in WSe$_2$ is much higher than in\nMoSe$_2$. It shows unique step-like increases in the momentum-resolved profile\nindicating opening of specific scattering channels. We study how different\nexternally accessible quantities, such as temperature or mirror reflectance,\nchange the optical response of polaritons. Our study contributes to an improved\nmicroscopic understanding of exciton-polaritons and their interaction with\nphonons, potentially suggesting experiments that could determine the energy of\ndark exciton states via momentum-resolved polariton absorption.",
        "positive": "Direct observation of vortices in an electron fluid: Vortices are the hallmarks of hydrodynamic flow. Recent studies indicate that\nstrongly-interacting electrons in ultrapure conductors can display signatures\nof hydrodynamic behavior including negative nonlocal resistance, Poiseuille\nflow in narrow channels, and a violation of the Wiedemann-Franz law. Here we\nprovide the first visualization of whirlpools in an electron fluid. By\nutilizing a nanoscale scanning superconducting quantum interference device on a\ntip (SQUID-on-tip) we image the current distribution in a circular chamber\nconnected through a small aperture to an adjacent narrow current carrying strip\nin high-purity type-II Weyl semimetal WTe2. In this geometry, the Gurzhi\nmomentum diffusion length and the size of the aperture determine the vortex\nstability phase diagram. We find that the vortices are present only for small\napertures, whereas the flow is laminar (non-vortical) for larger apertures,\nconsistent with the theoretical analysis of the hydrodynamic regime and in\ncontrast to the expectations of ballistic transport in WTe2 at low\ntemperatures. Moreover, near the vortical-to-laminar transition, we observe a\nsingle vortex in the chamber splitting into two vortices, a behavior that can\noccur only in the hydrodynamic regime and cannot be sustained by ballistic\ntransport. These findings suggest a novel mechanism of hydrodynamic flow:\ninstead of the commonly considered electron-electron scattering at the bulk,\nwhich becomes extremely weak at low temperatures, the spatial diffusion of\ncharge carriers' momenta is enabled by small-angle scattering at the planar\nsurfaces of thin pure crystals. This surface-induced para-hydrodynamics opens\nnew avenues for exploring and utilizing electron fluidics in high-mobility\nelectron systems."
    },
    {
        "anchor": "Controlling Photoluminescence Spectra of hBN Color Centers by Selective\n  Phonon-Assisted Excitation: A Theoretical Proposal: Color centers in hexagonal boron nitride (hBN) show stable single photon\nemission even at room temperature, making these systems a promising candidate\nfor quantum information applications. Besides this remarkable property, also\ntheir interaction with longitudinal optical (LO) phonons is quite unique\nbecause they lead to dominant phonon sidebands (PSBs), well separated from the\nzero phonon line (ZPL). In this work we utilize this clear spectral separation\nto theoretically investigate the influence of phonon decay dynamics on\ntime-dependent photoluminescence (PL) signals. Our simulations show, that by\nusing tailored optical excitation schemes it is possible to create a\nsuperposition between the two LO modes, leading to a phonon quantum beat that\nmanifests in the time-dependent PL signal.",
        "positive": "Nanodiamond-enhanced MRI: Nanodiamonds are of interest as nontoxic substrates for targeted drug\ndelivery and as highly biostable fluorescent markers for cellular tracking.\nBeyond optical techniques however, options for noninvasive imaging of\nnanodiamonds in vivo are severely limited. Here, we demonstrate that the\nOverhauser effect, a proton-electron double resonance technique developed to\ndetect free radicals in vivo, can enable high contrast magnetic resonance\nimaging (MRI) of nanodiamonds in water at room temperature and ultra-low\nmagnetic field. The technique transfers spin polarization from paramagnetic\nimpurities at nanodiamond surfaces to $^1$H spins in the surrounding water\nsolution, creating MRI contrast on-demand. We further examine the conditions\nrequired for maximum enhancement as well as the ultimate sensitivity of the\ntechnique. The ability to perform continuous hyperpolarization via the\nOverhauser mechanism, in combination with excellent in vivo stability, raises\nthe possibility of performing noninvasive tracking of nanodiamonds over\nindefinitely long periods of time."
    },
    {
        "anchor": "Bipolar Anodization Enables the Fabrication of Controlled Arrays of TiO2\n  Nanotube Gradients: We report here a new concept, the use of bipolar electrochemistry, which\nallows the rapid and wireless growth of self-assembled TiO2 NT layers that\nconsist of highly defined and controllable gradients in NT length and diameter.\nThe gradient height and slope can be easily tailored with the time of\nelectrolysis and the applied electric field, respectively. As this technique\nallows obtaining in one run a wide range of self-ordered TiO2 NT dimensions, it\nprovides the basis for rapid screening of TiO2 NT properties. In two examples,\nwe show how these gradient arrays can be used to screen for an optimized\nphotocurrent response from TiO2 NT based devices such as dye-sensitized solar\ncells.",
        "positive": "Raman scattering and electrical resistance of highly disordered graphene: Raman scattering (RS) spectra and current-voltage characteristics at room\ntemperature were measured in six series of small samples fabricated by means of\nelectron-beam lithography on the surface of a large size (5x5 mm) industrial\nmonolayer graphene film. Samples were irradiated by different doses of C${}^+$\nion beam up to $10^{15}$ cm${}^{-2}$. It was observed that at the utmost degree\nof disorder, the Raman spectra lines disappear which is accompanied by the\nexponential increase of resistance and change in the current-voltage\ncharacteristics.These effects are explained by suggestion that highly\ndisordered graphene film ceases to be a continuous and splits into separate\nfragments. The relationship between structure (intensity of RS lines) and\nsample resistance is defined. It is shown that the maximal resistance of the\ncontinuous film is of order of reciprocal value of the minimal graphene\nconductivity $\\pi h/4e^2\\approx 20$ kOhm."
    },
    {
        "anchor": "Plasmonic Properties of Close-packed Metallic Nanoparticle Mono- and\n  Bilayers: The self-assembly of metallic nanoparticles is a promising route to\nmetasurfaces with unique properties for many optical applications, such as\nsurface-enhanced spectroscopy, light manipulation, and sensing. We present an\nin-depth theoretical study of the optical properties of mono- and bilayers\nassembled from gold and silver nanoparticles. With finite-difference\ntime-domain simulations, we predict the occurrence of two plasmon modes, a\nbright and a dark mode, which exhibit symmetric and antisymmetric dipole\nconfigurations between the layers, respectively. The dark mode resonance energy\ndepends sensitively on the size of the particles and the interparticle gaps.\nHotspots with a nearfield intensity enhancement of up to 3000 are expected,\nwhich, together with the fact that the dark mode is roughly four times narrower\nthan the bright mode, reveals how promising these materials are for\nspectroscopy purposes.",
        "positive": "Single Spin Detection with a Carbon Nanotube Double Quantum Dot: Spin qubits defined in carbon nanotube quantum dots are of considerable\ninterest for encoding and manipulating quantum information because of the long\nelectron spin coherence times expected. However, before carbon nanotubes can\nfind applications in quantum information processing schemes, we need to\nunderstand and control the coupling between individual electron spins and the\ninteraction between the electron spins and their environment. Here we make use\nof spin selection rules to directly measure - and demonstrate control of - the\nsinglet-triplet exchange coupling between two carbon nanotube quantum dots. We\nfurthermore elucidate the effects of spin-orbit interaction on the electron\ntransitions and investigate the interaction of the quantum dot system with a\nsingle impurity spin - the ultimate limit in spin sensitivity."
    },
    {
        "anchor": "Visibility of dichalcogenide nanolayers: Dichalcogenides with the common formula MX2 are layered materials with\nelectrical properties that range from semiconducting to superconducting. Here,\nwe describe optimal imaging conditions for optical detection of ultrathin,\ntwo-dimensional dichalcogenide nanocrystals containing single, double and\ntriple layers of MoS2, WSe2 and NbSe2. A simple optical model is used to\ncalculate the contrast for nanolayers deposited on wafers with varying\nthickness of SiO2. The model is extended for imaging using the green channel of\na video camera. Using AFM and optical imaging we confirm that single layers of\nMoS2, WSe2 and NbSe2 can be detected on 90nm and 270 nm SiO2 using optical\nmeans. By measuring contrast under broad-band green illumination we are also\nable to distinguish between nanostructures containing single, mono and triple\nlayers of MoS2, WSe2 and NbSe2.",
        "positive": "Raman Images of a Single Molecule in a Highly Confined Plasmonic Field: Under the local plasmonic excitation, the Raman images of a single molecule\ncan now reach sub-nanometer resolution. We report here a theoretical\ndescription of the interaction between a molecule and a highly confined\nplasmonic field. It is shown that when the spatial distribution of the\nplasmonic field is comparable with the size of the molecule, the optical\ntransition matrix of the molecule becomes to be dependent on the position and\nthe spatial distribution of the plasmonic field, resulting in spatially\nresolved Raman image of a molecule. It is found that the resonant Raman image\nreflects the electronic transition density of the molecule. In combination with\nthe first principles calculations, the simulated Raman image of a porphyrin\nderivative adsorbed on the silver surface nicely reproduces its experimental\ncounterpart. The present theory provides the basic framework for describing\nlinear and nonlinear responses of molecules under the highly confined plasmonic\nfield."
    },
    {
        "anchor": "Observation of Hybrid-Order Topological Pump in a Kekule-Textured\n  Graphene Lattice: Thouless charge pumping protocol provides an effective route for realizing\ntopological particle transport. To date, the first-order and higher-order\ntopological pumps, exhibiting transitions of edge-bulk-edge and\ncorner-bulk-corner states, respectively, are observed in a variety of\nexperimental platforms. Here, we propose a concept of hybrid-order topological\npump, which involves a transition of bulk, edge, and corner states\nsimultaneously. More specifically, we consider a Kekul\\'e-textured graphene\nlattice that features a tunable phase parameter. The finite sample of zigzag\nboundaries, where the corner configuration is abnormal and inaccessible by\nrepeating unit cells, hosts topological responses at both the edges and\ncorners. The former is protected by a nonzero winding number, while the latter\ncan be explained by a nontrivial vector Chern number. Using our skillful\nacoustic experiments, we verify those nontrivial boundary landmarks and\nvisualize the consequent hybrid-order topological pump process directly. This\nwork deepens our understanding to higher-order topological phases and broadens\nthe scope of topological pumps.",
        "positive": "Vortices in Bose-Einstein Condensed Na Atoms: There are surface modes on the Bose-Einstein condensed Na atoms so that the\nnumber of vortices diverges when the stirring frequency becomes equal to that\nof the surface waves. We introduce the finite life time of the surface modes so\nthat the number of vortices becomes finite. Usually the number of vortices is a\nlinear function of the stirring frequency. We find that this linearity is\ndestroyed by the finite life time and a peaked function emerges with several\npeaks, one for each surface mode. The vortices become normal, as they should\nbe, so that there occurs a phase transition from normal to the superfluid\nstate."
    },
    {
        "anchor": "Optical properties of graphene antidot lattices: Undoped graphene is semi-metallic and thus not suitable for many electronic\nand optoelectronic applications requiring gapped semiconductor materials.\nHowever, a periodic array of holes (antidot lattice) renders graphene\nsemiconducting with a controllable band gap. Using atomistic modelling, we\ndemonstrate that this artificial nanomaterial is a dipole-allowed direct gap\nsemiconductor with a very pronounced optical absorption edge. Hence, optical\ninfrared spectroscopy should be an ideal probe of the electronic structure. To\naddress realistic experimental situations, we include effects due to disorder\nand the presence of a substrate in the analysis.",
        "positive": "Interacting electrons on a half line coupled to impurities: We generalize the bosonization methods for systems in the half line that we\ndiscussed elsewhere, to study the effects of interactions on electronic systems\ncoupled to impurities. We introduce a model for a quantum wire coupled with a\nquantum dot by a purely capacitive interaction. We show that the effect on the\nquantum wire is a dynamical boundary condition which reflects the charge\nfluctuations of the quantum dot. Special attention is given to the role of the\nfermion boundary conditions and their interplay with the electron interactions\non the bosonized effective theory."
    },
    {
        "anchor": "Geometrical optics limit of phonon transport in a channel of\n  disclinations: The presence of topological defects in a material can modify its electrical,\nacoustic or thermal properties. However, when a group of defects is present,\nthe calculations can become quite cumbersome due to the differential equations\nthat can emerge from the modeling. In this work, we express phonons as\ngeodesics of a 2 + 1 spacetime in the presence of a channel of dislocation\ndipoles in a crystalline environment described analytically in the continuum\nlimit with differential geometry methods. We show that such a simple model of\n1D array of topological defects is able to guide phonon waves. The presence of\ndefects indeed distorts the effective metric of the material, leading to an\nanisotropic landscape of refraction index which curves the path followed by\nphonons, with focusing/defocusing properties depending on the angle of the\nincident wave. As a consequence, using Boltzmann transfer equation, we show\nthat the defects may induce an enhancement or a depletion of the elastic energy\ntransport. We comment on the possibility of designing artificial materials\nthrough the presence of topological defects.",
        "positive": "Weak dynamical localization in periodically kicked cold atomic gases: Quantum kicked rotor was recently realized in experiments with cold atomic\ngases and standing optical waves. As predicted, it exhibits dynamical\nlocalization in the momentum space. Here we consider the weak localization\nregime concentrating on the Ehrenfest time scale. The later accounts for the\nspread-time of a minimal wavepacket and is proportional to the logarithm of the\nPlanck constant. We show that the onset of the dynamical localization is\nessentially delayed by four Ehrenfest times and give quantitative predictions\nsuitable for an experimental verification."
    },
    {
        "anchor": "Splitting of roton minimum in the \u03bd=5/2 Moore-Read state: We calculate the dynamical structure factor of the \\nu=5/2 non-abelian\nquantum Hall state in the dipole approximation, valid for large momenta. Due to\nthe fact that both quasi-particles (qps) and quasi-holes (qhs) have an internal\nMajorana degree of freedom, a qp-qh pair has a fermionic degree of freedom\nwhich can be either empty or occupied, and leads to a splitting of the roton\nmode. Observation of this splitting by means of finite wavelength optical\nspectroscopy could provide evidence for Majorana modes in the \\nu=5/2 quantum\nHall state.",
        "positive": "Ultralong 100 ns Spin Relaxation Time in Graphite at Room Temperature: Graphite has been intensively studied, yet its electron spins dynamics\nremains an unresolved problem even 70 years after the first experiments. The\ncentral quantities, the longitudinal ($T_1$) and transverse ($T_2$) relaxation\ntimes were postulated to be equal, mirroring standard metals, but $T_1$ has\nnever been measured for graphite. Here, based on a detailed band structure\ncalculation including spin-orbit coupling, we predict an unexpected behavior of\nthe relaxation times. We find, based on saturation ESR measurements, that $T_1$\nis markedly different from $T_2$. Spins injected with perpendicular\npolarization with respect to the graphene plane have an extraordinarily long\nlifetime of $100$ ns at room temperature. This is ten times more than in the\nbest graphene samples. The spin diffusion length across graphite planes is thus\nexpected to be ultralong, on the scale of $\\sim 70~\\mu$m, suggesting that thin\nfilms of graphite -- or multilayer AB graphene stacks -- can be excellent\nplatforms for spintronics applications compatible with 2D van der Waals\ntechnologies. Finally, we provide a qualitative account of the observed spin\nrelaxation based on the anisotropic spin admixture of the Bloch states in\ngraphite obtained from density functional theory calculations."
    },
    {
        "anchor": "Cavity-mediated electron hopping in disordered quantum Hall systems: We investigate the emergence of long-range electron hopping mediated by\ncavity vacuum fields in disordered quantum Hall systems. We show that the\ncounter-rotating (anti-resonant) light-matter interaction produces an effective\nhopping between disordered eigenstates within the last occupied Landau band.\nThe process involves a number of intermediate states equal to the Landau\ndegeneracy: each of these states consists of a virtual cavity photon and an\nelectron excited in the next Landau band with the same spin. We study such a\ncavity-mediated hopping mechanism in the dual presence of a random disordered\npotential and a wall potential near the edges, accounting for both paramagnetic\ncoupling and diamagnetic renormalization. We determine the cavity-mediated\nscattering rates, showing the impact on both bulk and edge states. The effect\nfor edge states is shown to increase when their energy approaches the\ndisordered bulk band, while for higher energy the edge states become\nasymptotically free. We determine the scaling properties while increasing the\nLandau band degeneracy. Consequences on the quantum Hall physics and future\nperspectives are discussed.",
        "positive": "Visibility recovery by strong interaction in an electronic Mach-Zehnder\n  interferometer: We study the evolution of a single-electron packet of Lorentzian shape along\nan edge of the integer quantum Hall regime or in a Mach-Zehnder interferometer,\nconsidering a capacitive Coulomb interaction and using a bosonization approach.\nWhen the packet propagates along a chiral quantum Hall edge, we find that its\nelectron density profile becomes more distorted from Lorentzian due to the\ngeneration of electron-hole excitations, as the interaction strength increases\nyet stays in a weak interaction regime. However, as the interaction strength\nbecomes larger and enters a strong interaction regime, the distortion becomes\nweaker and eventually the Lorentzian packet shape is recovered. The recovery of\nthe packet shape leads to an interesting feature of the interference visibility\nof the symmetric Mach-Zehnder interferometer whose two arms have the same\ninteraction strength. As the interaction strength increases, the visibility\ndecreases from the maximum value in the weak interaction regime, and then\nincreases to the maximum value in the strong interaction regime. We argue that\nthis counterintuitive result also occurs under other types of interactions."
    },
    {
        "anchor": "Computer-automated tuning procedures for semiconductor quantum dot\n  arrays: As with any quantum computing platform, semiconductor quantum dot devices\nrequire sophisticated hardware and controls for operation. The increasing\ncomplexity of quantum dot devices necessitates the advancement of automated\ncontrol software and image recognition techniques for rapidly evaluating charge\nstability diagrams. We use an image analysis toolbox developed in Python to\nautomate the calibration of virtual gates, a process that previously involved a\nlarge amount of user intervention. Moreover, we show that straightforward\nfeedback protocols can be used to simultaneously tune multiple tunnel couplings\nin a triple quantum dot in a computer automated fashion. Finally, we adopt the\nuse of a `tunnel coupling lever arm' to model the interdot barrier gate\nresponse and discuss how it can be used to more rapidly tune interdot tunnel\ncouplings to the GHz values that are compatible with exchange gates.",
        "positive": "Self-consistent Coulomb picture of an electron-electron bilayer system: In this work we implement the self-consistent Thomas-Fermi approach and a\nlocal conductivity model to an electron-electron bilayer system. The presence\nof an incompressible strip, originating from screening calculations at the top\n(or bottom) layer is considered as a source of an external potential\nfluctuation to the bottom (or top) layer. This essentially yields modifications\nto both screening properties and the magneto-transport quantities. The effect\nof the temperature, inter-layer distance and density mismatch on the density\nand the potential fluctuations are investigated. It is observed that the\nexistence of the incompressible strips plays an important role simply due to\ntheir poor screening properties on both screening and the magneto-resistance\n(MR) properties. Here we also report and interpret the observed MR Hysteresis\nwithin our model."
    },
    {
        "anchor": "Simulation of inelastic spin flip excitations and Kondo effect in STM\n  spectroscopy of magnetic molecules on metal substrates: Single-ion magnetic anisotropy in molecular magnets leads to spin flip\nexcitations that can be measured by inelastic scanning tunneling microscope\n(STM) spectroscopy. Here I present a semi ab initio scheme to compute the\nspectral features associated with inelastic spin flip excitations and Kondo\neffect of single molecular magnets. To this end density functional theory\ncalculations of the molecule on the substrate are combined with more\nsophisticated many-body techniques for solving the Anderson impurity problem of\nthe spin-carrying orbitals of the magnetic molecule coupled to the rest of the\nsystem, containing a phenomenological magnetic anisotropy term. For calculating\nthe STM spectra an exact expression for the dI/dV in the ideal STM limit, when\nthe coupling to the STM tip becomes negligibly small, is derived. In this limit\nthe dI/dV is simply related to the spectral function of the molecule-substrate\nsystem. For the case of an Fe porphyrin molecule on the Au(111) substrate, the\ncalculated STM spectra are in good agreement with recently measured STM\nspectra, showing the typical step features at finite bias associated with spin\nflip excitation of a spin-1 quantum magnet. For the case of Kondo effect in Mn\nporphyrin on Au(111), the agreement with the experimental spectra is not as\ngood due to the neglect of quantum interference in the tunneling.",
        "positive": "Polarization- and frequency-tunable microwave circuit for selective\n  excitation of nitrogen-vacancy spins in diamond: We report on a planar microwave resonator providing arbitrarily polarized\noscillating magnetic fields that enable selective excitation of the electronic\nspins of nitrogen-vacancy (NV) centers in diamond. The polarization plane is\nparallel to the surface of diamond, which makes the resonator fully compatible\nwith (111)-oriented diamond. The field distribution is spatially uniform in a\ncircular area with a diameter of 4 mm, and a near-perfect circular polarization\nis achieved. We also demonstrate that the original resonance frequency of 2.8\nGHz can be varied in the range of 2-3.2 GHz by introducing varactor diodes that\nserve as variable capacitors."
    },
    {
        "anchor": "Quantum Channel AlGaN/GaN/AlGaN High Electron Mobility Transistor: Scaling down the GaN channel in a double heterostructure AlGaN/GaN/AlGaN High\nElectron Mobility Transistor (HEMT) to the thicknesses on the order of or even\nsmaller than the Bohr radius confines electrons in the quantum well even at low\nsheet carrier densities. In contrast to the conventional designs, this Quantum\nChannel (QC) confinement is controlled by epilayer design and the polarization\nfield and not by the electron sheet density. As a result, the breakdown field\nat low sheet carrier densities increases by approximately 36% or even more\nbecause the quantization leads to an effective increase in the energy gap. In\naddition, better confinement increases the electron mobility at low sheet\ncarrier densities by approximately 50%. Another advantage is the possibility of\nincreasing the aluminum molar fraction in the barrier layer because a very thin\nlayer prevents material relaxation and the development of dislocation arrays.\nThis makes the QC especially suitable for high-voltage, high-frequency,\nhigh-temperature, and radiation-hard applications.",
        "positive": "Shift charge and spin photocurrents in Dirac surface states of\n  topological insulator: The generation of photocurrent in condensed matter is of main interest for\nphotovoltaic and optoelectronic applications. Shift current, a nonlinear\nphotoresponse, has attracted recent intensive attention as a dominant player of\nbulk photovoltaic effect in ferroelectric materials. In three dimensional\ntopological insulators $\\text{Bi}_2\\text{X}_3$ (X: Te, Se), we find that Dirac\nsurface states with a hexagonal warping term carry shift current by linearly\npolarized light. In addition, shift spin-current is introduced with the\ntime-reversal symmetry breaking perturbation. The estimate for the magnitudes\nof the shift charge- and spin-currents are 0.13$I_0$ and 0.21$I_0$(nA/m) with\nthe intensity of light $I_0$ measured in $(\\text{W}/\\text{m}^2)$, respectively,\nwhich can offer a useful method to generate these currents efficiently."
    },
    {
        "anchor": "Graphene's non-equilibrium fermions reveal Doppler-shifted magnetophonon\n  resonances accompanied by Mach supersonic and Landau velocity effects: Oscillatory magnetoresistance measurements on graphene have revealed a wealth\nof novel physics. These phenomena are typically studied at low currents. At\nhigh currents, electrons are driven far from equilibrium with the atomic\nlattice vibrations so that their kinetic energy can exceed the thermal energy\nof the phonons. Here, we report three non-equilibrium phenomena in monolayer\ngraphene at high currents: (i) a \"Doppler-like\" shift and splitting of the\nfrequencies of the transverse acoustic (TA) phonons emitted when the electrons\nundergo inter-Landau level (LL) transitions; (ii) an intra-LL Mach effect with\nthe emission of TA phonons when the electrons approach supersonic speed, and\n(iii) the onset of elastic inter-LL transitions at a critical carrier drift\nvelocity, analogous to the superfluid Landau velocity. All three quantum\nphenomena can be unified in a single resonance equation. They offer avenues for\nresearch on out-of-equilibrium phenomena in other two-dimensional fermion\nsystems.",
        "positive": "Electroluminescence from a polythiophene molecular wire suspended in a\n  plasmonic scanning tunneling microscope junction: The electroluminescence of a polythiophene wire suspended between two\nmetallic electrodes is probed using a scanning tunneling microscope. Under\npositive sample voltage, the spectral and voltage dependencies of the emitted\nlight are consistent with the fluorescence of the wire junction mediated by\nlocalized plasmons. This emission is strongly attenuated for the opposite\npolarity. Both emission mechanism and polarity dependence are similar to what\noccurs in organic light emitting diodes (OLED) but at the level of a single\nmolecular wire."
    },
    {
        "anchor": "Transport, refraction and interface arcs in junctions of Weyl semimetals: We study the low-energy single-electron transport across a junction of two\nmagnetic Weyl semimetals, in which the anisotropy axes are tilted one respect\nto the other. Using a two-band model with a potential step, we compute the\ntransmission factor for normal and Klein tunneling and the refraction\nproperties of the interface as a function of the tilt angle. We show that the\ninterface acts as a beam splitter, separating electrons with different\nchiralities. We also characterize interface states, only appearing for finite\ntilt angle, which connect the projection of the Fermi surfaces on the two sides\nof the junction, and we discuss transport effects due to their interplay with\nFermi arcs.",
        "positive": "Quantitative Current-Voltage Characteristics in Molecular Junctions from\n  First Principles: Using self-energy-corrected density functional theory (DFT) and a coherent\nscattering-state approach, we explain current-voltage (IV) measurements of four\npyridine-Au and amine-Au linked molecular junctions with quantitative accuracy.\nParameter-free many-electron self-energy corrections to DFT Kohn-Sham\neigenvalues are demonstrated to lead to excellent agreement with experiments at\nfinite bias, improving upon order-of-magnitude errors in currents obtained with\nstandard DFT approaches. We further propose an approximate route for prediction\nof quantitative IV characteristics for both symmetric and asymmetric molecular\njunctions based on linear response theory and knowledge of the Stark shifts of\njunction resonance energies. Our work demonstrates that a quantitative,\ncomputationally inexpensive description of coherent transport in molecular\njunctions is readily achievable, enabling new understanding and control of\ncharge transport properties of molecular-scale interfaces at large bias\nvoltages."
    },
    {
        "anchor": "Existence of two-channel Kondo regime for tunneling impurities with\n  resonant scattering: Dynamical tunneling systems have been proposed earlier to display a\ntwo-channel Kondo effect, the orbital index of the particle playing the role of\na pseudospin in the equivalent Kondo problem, and the spin being a silent\nchannel index. However, as shown recently by Aleiner et al. [Phys. Rev. Lett.\n86, 2629 (2001)], the predicted two-channel Kondo behavior can never be\nobserved in the weak coupling regime, where the tunneling induced splitting of\nthe levels of the tunneling system always dominates the physics. Here we show\nthat the above scenario changes completely if the conduction electrons are\nscattered by resonant scattering off the tunneling impurity; Then - as a\nnon-perturbative analysis reveals - the two-channel Kondo regime can easily be\nreached.",
        "positive": "Corner states of two-dimensional second-order topological insulators\n  with a chiral symmetry and broken time reversal and charge conjugation: Two-dimensional second-order topological insulators are characterized by the\npresence of topologically protected zero-energy bound states localized at the\ncorners of a flake. In this paper we theoretically study the occurrence and\nfeatures of such corner states inside flakes in the shape of a convex polygon.\nWe consider two different models, both in Cartan class IIIA, the first obeying\ninversion symmetry and the other obeying a combined $\\pi/4$ rotation symmetry\nand time-reversal symmetry ($\\hat{C}_4^z\\hat{T}$). By using an analytical\neffective model of an edge corresponding to a massive Dirac fermion, we\ndetermine the presence of a corner state between two given edges by studying\nthe sign of their induced masses and derive general rules for flakes in the\nshape of a convex polygon. In particular, we find that the number of corner\nstates in a flake is always two in the first model, while in the second model\nthere are either 0, 2 or 4. To corroborate our findings, we focus on flakes of\nspecific shapes (a triangle and a square) and use a numerical finite-difference\napproach to determine the features of the corner states in terms of their\nprobability density. In the case of a triangular flake, we can change the\nposition of corner states by rotating the flake in the first model, while in\nthe second model we can also change their number. Remarkably, when the induced\nmass of an edge is zero the corresponding corner state becomes delocalized\nalong the edge. In the case of a square flake and the model with\n$\\hat{C}_4^z\\hat{T}$ symmetry, there is an orientation of the flake with\nrespect to the crystal axes, for which the corner states extend along the whole\nperimeter of the square."
    },
    {
        "anchor": "Pseudo-spin canting transition in bilayer quantum Hall ferromagnets: a\n  self-charging capacitor: For sufficiently strong in-plane magnetic field a $\\nu_T=1$ bilayer quantum\nHall pseudo-ferromagnet is expected to exhibit a soliton lattice. For\nsufficiently close layers and large in-plane field, we predict this\nincommensurate ``planar'' phase $P_I$ to undergo a reentrant pseudo-spin\ncanting transition to an incommensurate state $C_I$, with a finite out-of-plane\npseudo-magnetization component, corresponding to an interlayer charge imbalance\nin regions between solitons. At $T>0$ the transition is in the 2d compressible\nIsing universality class, and at T=0, the quantum transition is in heretofore\nunexplored universality class. The striking experimental signatures are the\nuniversal nonlinear charge-voltage and in-plane field relations, and the\ndivergence of the differential bilayer capacitance at the transition, resulting\nin a bilayer capacitor that spontaneously charges itself, even in the absence\nof an applied interlayer voltage.",
        "positive": "Record-high Anomalous Ettingshausen effect in a micron-sized magnetic\n  Weyl semimetal on-chip cooler: Solid-state cooling devices offer compact, quiet, reliable and\nenvironmentally friendly solutions that currently rely primarily on the\nthermoelectric (TE) effect. Despite more than two centuries of research,\nclassical thermoelectric coolers suffer from low efficiency which hampers wider\napplication. In this study, the less researched Anomalous Ettingshausen effect\n(AEE), a transverse thermoelectric phenomenon, is presented as a new approach\nfor on-chip cooling. This effect can be boosted in materials with non-trivial\nband topologies as demonstrated in the Heusler alloy $\\text{Co}_2\\text{MnGa}$.\nEnabled by the high quality of our material, in situ scanning thermal\nmicroscopy experiments reveal a record-breaking anomalous Ettingshausen\ncoefficient of $-2.1$~mV in $\\mu$m-sized on-chip cooling devices at room\ntemperature. A significant 44\\% of the effect is contributed by the intrinsic\ntopological properties, in particular the Berry curvature of\n$\\text{Co}_2\\text{MnGa}$, emphasising the unique potential of magnetic Weyl\nsemimetals for high-performance spot cooling in nanostructures."
    },
    {
        "anchor": "Conductivity of a superlattice with parabolic miniband: The static and high-frequency differential conductivity of a one-dimensional\nsuperlattice with parabolic miniband, in which the dispersion law is assumed to\nbe parabolic up to the Brillouin zone edge, are investigated theoretically.\nUnlike the earlier published works, devoted to this problem, the novel formula\nfor the static current density contains temperature dependence, which leads to\nthe current maximum shift to the low field side with increasing temperature.\nThe high-frequency differential conductivity response properties including the\ntemperature dependence is examined and opportunities of creating a terahertz\noscillator on Bloch electron oscillations in such superlattices are discussed.\nAnalysis shows that superlattices with parabolic miniband dispersion law may be\nused for generation and amplification of terahertz fields only at very low\ntemperatures.",
        "positive": "Hund nodal line semimetals: The case of twisted magnetic phase in the\n  double-exchange model: We propose a class of topological metals, which we dub \\emph{Hund nodal line\nsemimetals}, arising from the strong Coulomb interaction encoded in the Hund's\ncoupling between itinerant electrons and localized spins. We here consider a\nparticular twisted spin configuration, which is realized in the double exchange\nmodel which describes the manganite oxides. The resulting effective tetragonal\nlattice of electrons with hoppings tied to the local spin features an\nantiunitary \\emph{non-symmorphic} symmetry that in turn, together with another\nnon-symmorphic but unitary, glide mirror symmetry, protects crossings of a\ndouble pair of bands along a high-symmetry line on the Brillouin zone boundary.\nWe also discuss symmetry breaking arising from various perturbations of the\ntwisted phase. Our results may motivate further studies of other realizations\nof this state of matter, for instance in different spin backgrounds, properties\nof its drumhead surface states, as well as its stability to disorder and\ninteractions among the itinerant electrons."
    },
    {
        "anchor": "The Half-Full Landau Level: At even-denominator Landau level filling fractions, such as $\\nu=1/2$, the\nground state, in most cases, has no energy gap, and there is no quantized\nplateau in the Hall conductance. Nevertheless, the states exhibit non-trivial\nlow-energy phenomena. Open questions concerning the proper description of these\nsystems have attracted renewed attention during the last few years. Issues at\n$\\nu=1/2$ include consequences of particle-hole symmetry, which should be\npresent for a spin-aligned system in the limit where one can neglect mixing\nbetween Landau levels. Other issues concern questions of anisotropy and\ngeometry, properties at non-zero temperature, and effects of relatively strong\ndisorder. In cases where one does find a gapped even-denominator quantized Hall\nstate, such as $\\nu=5/2$ in GaAs structures, major questions have arisen about\nthe nature of the quantum state, which will be discussed briefly in this\nchapter. The chapter will also discuss phenomena that can occur in a\ntwo-component system near half filling, i.e., when the total filling factor\n$\\nu_{\\rm{tot}} $ is close to 1.",
        "positive": "Multiterminal Conductance of a Floquet Topological Insulator: We report on simulations of the dc conductance and quantum Hall response of a\nFloquet topological insulator using Floquet scattering theory. Our results\nreveal that laser-induced edge states in graphene lead to quantum Hall plateaus\nonce imperfect matching with the non-illuminated leads is lessened. But the\nmagnitude of the Hall plateaus is not directly related to the number and\nchirality of all the edge states at a given energy as usual. Instead, the\nplateaus are dominated only by those edge states adding to the dc density of\nstates. Therefore, the dc quantum Hall conductance of a Floquet topological\ninsulator is not directly linked to topological invariants of the full the\nFloquet bands."
    },
    {
        "anchor": "Magnetoelectric Coupling and Electric Control of Magnetization in\n  Ferromagnet-Ferroelectric-Metal Superlattices: Ferromagnet-ferroelectric-metal superlattices are proposed to realize the\nlarge room-temperature magnetoelectric effect. Spin dependent electron\nscreening is the fundamental mechanism at the microscopic level. We also\npredict an electric control of magnetization in this structure. The naturally\nbroken inversion symmetry in our tri-component structure introduces a\nmagnetoelectric coupling energy of $P M^2$. Such a magnetoelectric coupling\neffect is general in ferromagnet-ferroelectric heterostructures, independent of\nparticular chemical or physical bonding, and will play an important role in the\nfield of multiferroics.",
        "positive": "On the nature of the spin polarization limit in the warped Dirac cone of\n  the Bi2Te3: The magnitude of electron spin polarization in topologically protected\nsurface states is an important parameter with respect to spintronics\napplications. In order to analyze the warped spin texture in Bi$_2$Te$_3$ thin\nfilms, we combine angle- and spin-resolved photoemission experiments with\ntheoretical \\textit{ab initio} calculations. We find an \\textit{in-plane} spin\npolarization of up to $\\sim$~45\\% in the topologically protected Dirac cone\nstates near the Fermi level. The Fermi surface of the Dirac cone state is\nwarped and shows an \\textit{out-of-plane} spin polarization of $\\sim$~15\\%.\nThese findings are in quantitative agreement with dedicated simulations which\nfind electron density of the Dirac cone delocalized over the first quintuple\nlayer with spin reversal occurring in the surface atomic layer."
    },
    {
        "anchor": "Magnetic-field dependence of energy levels in ultrasmall metal grains: We present a theory of mesoscopic fluctuations of g tensors and avoided\ncrossing energies in a small metal grain. The model, based on random matrix\ntheory, contains both the orbital and spin contributions to the g tensor. The\ntwo contributions can be experimentally separated for weak spin-orbit coupling\nwhile they merge in the strong coupling limit. For intermediate coupling,\nsubstantial correlations are found between g factors of neighboring levels.",
        "positive": "Optical detection of Mott and generalized Wigner crystal states in\n  WSe2/WS2 moir\u00e9 superlattices: Moir\\'e superlattices are emerging as a new route for engineering strongly\ncorrelated electronic states in two-dimensional van der Waals heterostructures,\nas recently demonstrated in the correlated insulating and superconducting\nstates in magic-angle twisted bilayer graphene and ABC trilayer graphene/boron\nnitride moir\\'e superlattices. Transition metal dichalcogenide (TMDC) moir\\'e\nheterostructures provide another exciting model system to explore correlated\nquantum phenomena, with the addition of strong light-matter interactions and\nlarge spin-orbital coupling. Here we report the optical detection of strongly\ncorrelated phases in semiconducting WSe2/WS2 moir\\'e superlattices. Our\nsensitive optical detection technique reveals a Mott insulator state at one\nhole per superlattice site ({\\nu} = 1), and surprising insulating phases at\nfractional filling factors {\\nu} = 1/3 and 2/3, which we assign to generalized\nWigner crystallization on an underlying lattice. Furthermore, the unique\nspin-valley optical selection rules of TMDC heterostructures allow us to\noptically create and investigate low-energy spin excited states in the Mott\ninsulator. We reveal an especially slow spin relaxation lifetime of many\nmicroseconds in the Mott insulating state, orders-of-magnitude longer than that\nof charge excitations. Our studies highlight novel correlated physics that can\nemerge in moir\\'e superlattices beyond graphene."
    },
    {
        "anchor": "Identifying Chern numbers of superconductors from local measurements: Fascination in topological materials originates from their remarkable\nresponse properties and exotic quasiparticles which can be utilized in quantum\ntechnologies. In particular, large-scale efforts are currently focused on\nrealizing topological superconductors and their Majorana excitations. However,\ndetermining the topological nature of superconductors with current experimental\nprobes is an outstanding challenge. This shortcoming has become increasingly\npressing due to rapidly developing designer platforms which are theorized to\ndisplay very rich topology and are better accessed by local probes rather than\ntransport experiments. We introduce a robust machine-learning protocol for\nclassifying the topological states of two-dimensional (2D) chiral\nsuperconductors and insulators from local density of states (LDOS) data. Since\nthe LDOS can be measured with standard experimental techniques, our protocol\ncontributes to overcoming the almost three decades standing problem of\nidentifying the topological phase of 2D superconductors with broken\ntime-reversal symmetry.",
        "positive": "Electronic Correlations in Double Quantum Dots: We present a study of the electronic structure of two laterally coupled\ngaussian quantum dots filled with two particles. The exact diagonalization\nmethod has been used in order to inspect the spatial correlations and examine\nthe particular spin singlet-triplet configurations for different coupling\ndegrees between quantum dots. The outcome of our research shows this structure\nto have highly modifiable properties promoting it as an interesting quantum\ndevice, showing the possible use of this states as a quantum bit gate."
    },
    {
        "anchor": "Electron Cotunneling in a Semiconductor Quantum Dot: We report transport measurements on a semiconductor quantum dot with a small\nnumber of confined electrons. In the Coulomb blockade regime, conduction is\ndominated by cotunneling processes. These can be either elastic or inelastic,\ndepending on whether they leave the dot in its ground state or drive it into an\nexcited state, respectively. We are able to discriminate between these two\ncontributions and show that inelastic events can occur only if the applied bias\nexceeds the lowest excitation energy. Implications to energy-level spectroscopy\nare discussed.",
        "positive": "Multi-messenger nano-probes of hidden magnetism in a strained manganite: The ground state properties of correlated electron systems can be\nextraordinarily sensitive to external stimuli, such as temperature, strain, and\nelectromagnetic fields, offering abundant platforms for functional materials.\nWe present a metastable and reversible photoinduced ferromagnetic transition in\nstrained films of the doped manganite La(2/3)Ca(1/3)MnO3. Using the novel\nmulti-messenger combination of atomic force microscopy, cryogenic scanning\nnear-field optical microscopy, magnetic force microscopy, and ultrafast laser\nexcitation, we demonstrate both \"writing\" and \"erasing\" of a metastable\nferromagnetic metal phase with nanometer-resolved finesse. By tracking both\noptical conductivity and magnetism at the nano-scale, we reveal how spontaneous\nstrain underlies the thermal stability, persistence, and reversal of this\nphotoinduced metal. Our first-principles electronic structure calculations\nreveal how an epitaxially engineered Jahn-Teller distortion can stabilize\nnearly degenerate antiferromagnetic insulator and ferromagnetic metal phases.\nWe propose a Ginzburg-Landau description to rationalize the co-active interplay\nof strain, lattice distortion, and magnetism we resolve in strained LCMO, thus\nguiding future functional engineering of epitaxial oxides like manganites into\nthe regime of phase-programmable materials."
    },
    {
        "anchor": "On the sample-dependent minimal conductivity in weakly disordered\n  graphene: We present a unified understanding of the experimentally observed minimal dc\nconductivity in weakly disordered graphene. Firstly, based on linear response\ntheory, we reveal that randomness or disorder inevitably induces momentum\ndependent corrections to the electron self-energy function, which naturally\nyields a sample-dependent minimal conductivity. Taking the long-ranged Gaussian\nand Coulomb potentials as examples, we derive the momentum dependent\nself-energy function within the Born approximation, and further validate it via\nnumerical simulations using the large-scale Lanczos algorithm. The explicit\nmomentum dependences of the self-energy on the intensity, concentration and\nrange of potential are critically addressed. Therefore, our results provide a\nreasonable interpretation of the sample-dependent minimal conductivity observed\nin graphene samples.",
        "positive": "Phonon wind and drag of excitons in monolayer semiconductors: We study theoretically the non-equilibrium exciton transport in monolayer\ntransition metal dichalcogenides. We consider the situation where excitons\ninteract with non-equilibrium phonons, e.g., under the conditions of localized\nexcitation where a ``hot spot'' in formed. We develop the theory of the exciton\ndrag by the phonons and analyze in detail the regimes of diffusive propagation\nof phonons and ballistic propagation of phonons where the phonon wind is\nformed. We demonstrate that a halo-like spatial distribution of excitons akin\nobserved in [Phys. Rev. Lett. 120, 207401 (2018)] can be formed as a result of\nthe exciton drag by non-equilibrium phonons or Seebeck effect."
    },
    {
        "anchor": "Localized charge bifurcation in the coupled quantum dots: We analyzed theoretically localized charge relaxation in a double quantum dot\n(QD) system coupled with continuous spectrum states in the presence of\nlocalized electrons Coulomb interaction in a single QD. We have found that for\na wide range of system parameters charge relaxation occurs through two stable\nregimes with significantly different relaxation rates. A peculiar time moment\nexists in the system at which rapid switching between stable regimes takes\nplace. We consider this phenomenon to be applicable for creation of active\nelements in nano-electronics based on the fast transition effect between two\nstable states.",
        "positive": "Current carried by evanescent modes and possible device application: Quantum tunneling of an electron through a classically forbidden regime has\nno classical analogue and several aspects of it are still not well understood.\nIn this work we analyze electronic currents under the barrier. For this we\nconsider a multichannel Aharonov-Bohm ring and developed a correct formalism to\ncalculate the currents inside the ring when the states are evanescent. We also\nshow unlike other proposed quantum devices that such currents and associated\nconductance are not very sensitive to changes in material parameters and thus\nthe system can be used to build stable devices that work on magnetic and\ntransport properties. We also study the current magnification property of the\nring in presence of both propagating and evanescent states."
    },
    {
        "anchor": "Highly anisotropic thermoelectric properties of carbon sulfide\n  monolayers: Strain engineering applied to carbon monosulphide monolayers allows to\ncontrol the bandgap, controlling electronic and thermoelectric responses.\nHerein, we study the semiconductor-metal phase transition of this layered\nmaterial driven by strain control on the basis of first-principles\ncalculations. We consider uniaxial and biaxial tensile strain and we find a\nhighly anisotropic electronic and thermoelectonic responses depending on the\ndirection of the applied strain. Our results indicate that strain-induced\nresponse could be an effective method to control the electronic response and\nthe thermoelectric performance.",
        "positive": "Tunable ${\\cal \u03c7/PT}$ Symmetry in Noisy Graphene: We investigate the resonant regime of a mesoscopic cavity made of graphene or\na doped beam splitter. Using Non-Hermitian Quantum Mechanics, we consider the\nBender-Boettcher assumption that a system must obey parity and time reversal\nsymmetry. Therefore, we describe such system by coupling chirality, parity and\ntime reversal symmetries through the scattering matrix formalism and apply it\nin the shot noise functions, also derived here. Finally we show how to achieve\nthe resonant regime only by setting properly the parameters concerning the\nchirality and the PT symmetry."
    },
    {
        "anchor": "Dirac cones in the spectrum of bond-decorated graphenes: We present a two-band model based on periodic H\\\"uckel theory, which is\ncapable of predicting the existence and position of Dirac cones in the first\nBrillouin zone of an infinite class of two-dimensional periodic carbon\nnetworks, obtained by systematic perturbation of the graphene connectivity by\nbond decoration, that is by inclusion of arbitrary $\\pi$-electron H\\\"uckel\nnetworks into each of the three carbon-carbon $\\pi$-bonds within the graphene\nunit cell. The bond decoration process can fundamentally modify the graphene\nunit cell and honeycomb connectivity, representing a simple and general way to\ndescribe many cases of graphene chemical functionalization of experimental\ninterest, such as graphyne, janusgraphenes and chlorographenes. Exact\nmathematical conditions for the presence of Dirac cones in the spectrum of the\nresulting two-dimensional $\\pi$-networks are formulated in terms of the\nspectral properties of the decorating graphs. Our method predicts the existence\nof Dirac cones in experimentally characterized janusgraphenes and\nchlorographenes, recently speculated on the basis of DFT calculations. For\nthese cases, our approach provides a proof of the existence of Dirac cones, and\ncan be carried out at the cost of a back of the envelope calculation, bypassing\nany diagonalization step, even within H\\\"uckel theory.",
        "positive": "Probing Transverse Magnetic Anisotropy by Electronic Transport through a\n  Single-Molecule Magnet: By means of electronic transport, we study the transverse magnetic anisotropy\nof an individual Fe$_4$ single-molecule magnet (SMM) embedded in a\nthree-terminal junction. In particular, we determine in situ the transverse\nanisotropy of the molecule from the pronounced intensity modulations of the\nlinear conductance, which are observed as a function of applied magnetic field.\nThe proposed technique works at temperatures exceeding the energy scale of the\ntunnel splittings of the SMM. We deduce that the transverse anisotropy for a\nsingle Fe$_4$ molecule captured in a junction is substantially larger than the\nbulk value."
    },
    {
        "anchor": "Effects of Coulomb screening and disorder on artificial graphene based\n  on nanopatterned semiconductor: A residual disorder in the gate system is the main problem on the way to\ncreate artificial graphene based on two-dimensional electron gas. The disorder\ncan be significantly screened/reduced due to the many-body effects. To analyse\nthe screening/disorder problem we consider AlGaAs/GaAs/AlGaAs heterostructure\nwith two metallic gates. We demonstrate that the design least susceptible to\nthe disorder corresponds to the weak coupling regime (opposite to tight\nbinding) which is realised via system of quantum anti-dots. The most relevant\ntype of disorder is the area disorder which is a random variation of areas of\nquantum anti-dots. The area disorder results in formation of puddles. Other\ntypes of disorder, the position disorder and the shape disorder, are\npractically irrelevant. The formation/importance of puddles dramatically\ndepends on parameters of the nanopatterned heterostructure. A variation of the\nparameters by 20--30\\% can change the relative amplitude of puddles by orders\nof magnitude. Based on this analysis we formulate criteria for the acceptable\ndesign of the heterostructure aimed at creation of the artificial graphene.",
        "positive": "Localized plasmons in graphene-coated nanospheres: We present an analytical derivation of the electromagnetic response of a\nspherical object coated by a conductive film, here exemplified by a graphene\ncoating. Applying the framework of Mie-Lorenz theory augmented to account for a\nconductive boundary condition, we derive the multipole scattering coefficients,\nmodified essentially through the inclusion of an additive correction in\nnumerator and denominator. By reductionist means, starting from the retarded\nresponse, we offer simple results in the quasistatic regime by analyzing the\nmultipolar polarizability and associated dispersion equation for the localized\nplasmons. We consider graphene coatings of both dielectric and conducting\nspheres, where in the former case the graphene coating introduces the plasmons\nand in the latter case modifies in interesting ways the existing ones. Finally,\nwe discuss our analytical results in the context of extinction cross-section\nand local density of states. Recent demonstrations of fabricated spherical\ngraphene nanostructures make our study directly relevant to experiments."
    },
    {
        "anchor": "Topological Edge States with Zero Hall Conductivity in a Dimerized\n  Hofstadter Model: The Hofstadter model is a simple yet powerful Hamiltonian to study quantum\nHall physics in a lattice system, manifesting its essential topological states.\nLattice dimerization in the Hofstadter model opens an energy gap at half\nfilling. Here we show that even if the ensuing insulator has a Chern number\nequal to zero, concomitantly a doublet of edge states appear that are pinned at\nspecific momenta. We demonstrate that these states are topologically protected\nby inversion symmetry in specific one-dimensional cuts in momentum space,\ndefine and calculate the corresponding invariants and identify a platform for\nthe experimental detection of these novel topological states.",
        "positive": "Tuning quantum non-local effects in graphene plasmonics: The response of an electron system to electromagnetic fields with sharp\nspatial variations is strongly dependent on quantum electronic properties, even\nin ambient conditions, but difficult to access experimentally. We use\npropagating graphene plasmons, together with an engineered dielectric-metallic\nenvironment, to probe the graphene electron liquid and unveil its detailed\nelectronic response at short wavelengths.The near-field imaging experiments\nreveal a parameter-free match with the full theoretical quantum description of\nthe massless Dirac electron gas, in which we identify three types of quantum\neffects as keys to understanding the experimental response of graphene to\nshort-ranged terahertz electric fields. The first type is of single-particle\nnature and is related to shape deformations of the Fermi surface during a\nplasmon oscillations. The second and third types are a many-body effect\ncontrolled by the inertia and compressibility of the interacting electron\nliquid in graphene. We demonstrate how, in principle, our experimental approach\ncan determine the full spatiotemporal response of an electron system."
    },
    {
        "anchor": "Light matter interaction in WS$_{2}$ nanotube-graphene hybrid devices: We study the light matter interaction in WS$_{2}$ nanotube-graphene hybrid\ndevices. Using scanning photocurrent microscopy we find that by engineering\ngraphene electrodes for WS$_{2}$ nanotubes we can improve the collection of\nphotogenerated carriers. We observe inhomogeneous spatial photocurrent response\nwith an external quantum efficiency of $\\sim 1\\%$ at 0 V bias. We show that\ndefects play an important role and can be utilized to enhance and tune\nphotocarrier generation.",
        "positive": "Polaron spectroscopy of a bilayer excitonic insulator: Recent advances in fabrication of two dimensional materials and their moir\\'e\nheterostructures have opened up new avenues for realization of ground-state\nexcitonic insulators, where the structure spontaneously develops a finite\ninterlayer electronic polarization. We propose and analyze a scheme where an\noptically generated intralayer exciton is screened by excitations out of the\nexcitonic insulator to form interlayer polarons. Using Quantum Monte-Carlo\ncalculations we first determine the binding energy of the biexciton state\ncomposed of inter- and intralayer excitons, which plays a central role in\nunderstanding polaron formation. We describe the excitations out of the\nground-state condensate using BCS theory and use a single\ninteracting-quasiparticle-pair excitation Ansatz to describe dynamical\nscreening of optical excitations. Our predictions carry the hallmarks of the\nexcitonic insulator excitation spectrum and show how changing the interlayer\nexciton binding energy by increasing the layer separation modifies the optical\nspectra."
    },
    {
        "anchor": "Quantum oscillations of dissipative resistance in crossed electric and\n  magnetic fields: Oscillations of dissipative resistance of two-dimensional electrons in GaAs\nquantum wells are observed in response to an electric current I and a strong\nmagnetic field applied perpendicular to the two-dimensional systems. Period of\nthe current-induced oscillations does not depend on the magnetic field and\ntemperature. At a fixed current the oscillations are periodic in inverse\nmagnetic fields with a period that does not depend on dc bias. The proposed\nmodel considers spatial variations of electron filling factor, which are\ninduced by the electric current, as the origin of the resistance oscillations.",
        "positive": "Spin Diffusion in Spin Glasses Require Two Magnetic Variables, $\\vec{M}$\n  and $\\vec{m}$: Experiment has established that spin-glasses can support a steady-state spin\ncurrent $\\vec{j}_{i}$. However, the accepted theory of spin glass dynamics\npermits oscillations but no steady-state spin current. Onsager's irreversible\nthermodynamics implies that the spin current is proportional to the gradient of\na magnetization. We argue, however, that the magnon distribution function\nassociated with the local equilibrium magnetization $\\vec{M}$ cannot diffuse\nbecause it represents $10^{23}$ variables. We therefore invoke the\nnon-equilibrium magnetization $\\vec{m}$, which in spintronics is called the\n{\\it spin accumulation}. Applying the theory of irreversible thermodynamics we\nindeed find that it predicts spin diffusion, and we consider other experimental\nconsequences of the theory, including a wavelength-dependent coupling between\nthe reactive and the diffusive degrees of freedom."
    },
    {
        "anchor": "Non-equilibrium spin accumulation in ferromagnetic single-electron\n  transistors: We study transport in ferromagnetic single-electron transistors. The non-\nequilibrium spin accumulation on the island caused by a finite current through\nthe system is described by a generalized theory of the Coulomb blockade. It\nenhances the tunnel magnetoresistance and has a drastic effect on the time-\ndependent transport properties. A transient decay of the spin accumulation may\nreverse the electric current on time scales of the order of the spin-flip\nrelaxation time. This can be used as an experimental signature of the non-\nequilibrium spin accumulation.",
        "positive": "Photoinduced Nonperturbative Valley Polarization in Graphene: We investigate a valleytronic device based on graphene with charge separation\nat different sublattices and correspondingly at nonequivalent valleys. We\ncharacterize the maximality condition of valley polarization and investigate\nthe parameters and conditions upon which we can coherently control the carriers\nand store data via valley degree of freedom. The valley polarization is\ncontrolled by the amplitude as well as the carrier envelope phase of the pulse\nand the curvature of the electron trajectory in the reciprocal space. When\nstrong field excitation is taken into account, the optical selection rule in\nperturbative optics is replaced by the nonadiabatic geometric effects. As a\nresult, a nonperturbative valley polarization in two dimensional Dirac\nmaterials is induced regardless of having an intrinsic bandgap.\nMicroscopically, such a nonreciprocal response of graphene in the chiral\nelectric field is encoded by the quantum Berry phase, as a (pseudo)\nmagnetoelectric monopole."
    },
    {
        "anchor": "High-temperature fusion of a multi-electron leviton: The state of electrons injected onto the surface of the Fermi sea depends on\ntemperature. The state is pure at zero temperature and is mixed at finite\ntemperature. In the case of a single-electron injection, such a transformation\ncan be detected as a decrease in shot noise with increasing temperature. In the\ncase of a multi-electron injection, the situation is more subtle. The mixedness\nhelps the development of quantum-mechanical exchange correlations between\ninjected electrons, even if such correlations are absent at zero temperature.\nThese correlations enhance the shot noise, what in part counteracts the\nreduction of noise with temperature. Moreover, at sufficiently high\ntemperatures, the correlation contribution to noise predominates over the\ncontribution of individual particles. As a result, in the system of $N$\nelectrons, the apparent charge (which is revealed via the shot noise) is\nchanged from $e$ at zero temperature to $Ne$ at high temperatures. It looks\nlike the exchange correlations glue up electrons into one particle of total\ncharge and energy. This point of view is supported by both charge noise and\nheat noise. Interestingly, in the macroscopic limit, $N\\to \\infty$, the\ncorrelation contribution completely suppresses the effect of temperature on\nnoise.",
        "positive": "Observation of an intrinsic bandgap and Landau level renormalization in\n  graphene/boron-nitride heterostructures: Van der Waals heterostructures formed by assembling different two-dimensional\natomic crystals into stacks can lead to many new phenomena and device\nfunctionalities. In particular, graphene/boron-nitride heterostructures have\nemerged as a very promising system for band engineering of graphene. However,\nthe intrinsic value and origin of the bandgap in such heterostructures remain\nunresolved. Here we report the observation of an intrinsic bandgap in epitaxial\ngraphene/boron-nitride heterostructures with zero crystallographic alignment\nangle. Magneto-optical spectroscopy provides a direct probe of the Landau level\ntransitions in this system and reveals a bandgap of ~ 38 meV (440 K). Moreover,\nthe Landau level transitions are characterized by effective Fermi velocities\nwith a critical dependence on specific transitions and magnetic field. These\nfindings highlight the important role of many body interactions in determining\nthe fundamental properties of graphene heterostructures."
    },
    {
        "anchor": "Driven Hofstadter Butterflies and Related Topological Invariants: The properties of the Hofstadter butterfly, a fractal, self similar spectrum\nof a two dimensional electron gas, are studied in the case where the system is\nadditionally illuminated with monochromatic light. This is accomplished by\napplying Floquet theory to a tight binding model on the honeycomb lattice\nsubjected to a perpendicular magnetic field and either linearly or circularly\npolarized light. It is shown how the deformation of the fractal structure of\nthe spectrum depends on intensity and polarization. Thereby, the topological\nproperties of the Hofstadter butterfly in presence of the oscillating electric\nfield are investigated. A thorough numerical analysis of not only the Chern\nnumbers but also the $W_{3}$-invariants gives the appropriate insight into the\ntopology of this driven system. This includes a comparison of a direct\n$W_3$-calculation to the method based on summing up Chern numbers of the\ntruncated Floquet Hamiltonian.",
        "positive": "Fluorescence from a few electrons: Systems containing few Fermions (e.g., electrons) are of great current\ninterest. Fluorescence occurs when electrons drop from one level to another\nwithout changing spin. Only electron gases in a state of equilibrium are\nconsidered. When the system may exchange electrons with a large reservoir, the\nelectron-gas fluorescence is easily obtained from the well-known Fermi-Dirac\ndistribution. But this is not so when the number of electrons in the system is\nprevented from varying, as is the case for isolated systems and for systems\nthat are in thermal contact with electrical insulators such as diamond. Our\naccurate expressions rest on the assumption that single-electron energy levels\nare evenly spaced, and that energy coupling and spin coupling between electrons\nare small. These assumptions are shown to be realistic for many systems.\nFluorescence from short, nearly isolated, quantum wires is predicted to drop\nabruptly in the visible, a result not predicted by the Fermi-Dirac\ndistribution. Our exact formulas are based on restricted and unrestricted\npartitions of integers. The method is considerably simpler than the ones\nproposed earlier, which are based on second quantization and contour\nintegration."
    },
    {
        "anchor": "A simple all-inorganic hole-only device structure for monitoring the\n  trap densities in perovskite solar cells: One of the most critical challenges in soaring the performance of perovskite\nsolar cells is decreasing the density of trap states in the light-absorbing\nperovskite layer. These traps cause an increase in the recombination of charge\ncarriers and decrease the efficiency of devices. One of the methods to study\nthe trap density is space charge limited current (SCLC) analysis. For this\npurpose, some structures are needed with the ability to transport only\nelectrons or holes. The trap density can be calculated by investigating the\ncurrent-voltage diagram and finding the voltage corresponding to the slope\nchange point. One of the challenges in these structures is using organic\npolymers like Spiro-OMeTAD, PEDOT: PSS, and PTAA as hole transport layers. They\nhave problems like high acidity, lack of stability against moisture, low charge\nmobility, low conductivity, and high cost. In this work, a hole-only device\nstructure is explained, made based on inorganic materials, which possesses high\nstability, a simple preparation method, and reasonable cost compared to\nconventional hole-only device structures. This structure is built by coating a\nnanostructured NiOx layer, perovskite, CIS, and Au on the ITO substrate. To\ninvestigate the performance of this structure, various perovskite layers were\nmade at different experimental conditions, and their trap density was obtained\nby the proposed hole-only device structure. The analysis of the photovoltaic\ncharacteristics of cells revealed a clear correlation between the perovskite\nlayer's trap density and the cells' performance. Our results show the\nintroduced structure is a simple and stable structure that can be utilized in\nstudying the trap density in perovskite layers to make more efficient cells.",
        "positive": "Tunneling Via Individual Electronic States in Ferromagnetic\n  Nanoparticles: We measure electron tunneling via discrete energy levels in ferromagnetic\ncobalt particles less than 4 nm in diameter, using non-magnetic electrodes. Due\nto magnetic anisotropy, the energy of each tunneling resonance shifts as an\napplied magnetic field rotates the particle's magnetic moment. We see both\nspin-increasing and decreasing tunneling transitions, but we do not observe the\nspin degeneracy at small magnetic fields seen previously in non-magnetic\nmaterials. The tunneling spectrum is denser than predicted for independent\nelectrons, possibly due to spin-wave excitations."
    },
    {
        "anchor": "Trion Species-Resolved Quantum Beats in MoSe2: Monolayer photonic materials offer a tremendous potential for on-chip\noptoelectronic devices. Their realization requires knowledge of optical\ncoherence properties of excitons and trions that have so far been limited to\nnonlinear optical experiments carried out with strongly inhomogenously\nbroadened material. Here we employ h-BN encapsulated and electrically gated\nMoSe2 to reveal coherence properties of trion-species directly in the linear\noptical response. Autocorrelation measurements reveal long dephasing times up\nto T2=1.16+-0.05 ps for positively charged excitons. Gate dependent\nmeasurements provide evidence that the positively-charged trion forms via\nspatially localized hole states making this trion less prone to dephasing in\nthe presence of elevated hole carrier concentrations. Quantum beat signatures\ndemonstrate coherent coupling between excitons and trions that have a dephasing\ntime up to 0.6 ps, a two-fold increase over those in previous reports. A key\nmerit of the prolonged exciton/trion coherences is that they were achieved in a\nlinear optical experiment, and thus are directly relevant to applications in\nnanolasers, coherent control, and on-chip quantum information processing\nrequiring long photon coherence.",
        "positive": "Bias-dependent D'yakonov-Perel' spin relaxation in bilayer graphene: We calculate the spin relaxation time of mobile electrons due to spin\nprecession between random impurity scattering (D'yakonov-Perel' mechanism) in\nelectrically gated bilayer graphene analytically and numerically. Due to the\ntrigonal warping of the bandstructure, the spin relaxation time exhibits an\ninteresting non-monotonic behavior as a function of both the Fermi energy and\nthe interlayer bias potential. Our results are in good agreement with recent\nfour-probe measurements of the spin relaxation time in bilayer graphene and\nindicate the possibility of an electrically-switched spin device."
    },
    {
        "anchor": "Ultrafast near-field imaging of exciton-polariton dynamics in WSe_2\n  waveguides at room temperature: Van der Waals (vdW) materials, weakly bound layered compounds, have received\nenormous interest as they offer a malleable playground for a wide range of\nphysical properties in thermal, electronic and optical devices. In particular,\nowing to their inherent deep subwavelength light confinement, they support a\nvariety of light-matter interactions phenomena such as plasmons, excitons and\nphonons conveyed as polaritonic modes. Specifically, semiconductor vdW\nmaterials such as WSe_2 are particularly attractive for photonic and quantum\nintegrated technologies since they sustain VIS-NIR exciton-polariton modes at\nroom temperature. In the quest to unravel the underlying physics of these\nintriguing phenomena, advanced subdiffraction imaging techniques such as SNOM\nhas provided valuable insights on the nature of the EP coupling mechanism to\nthe waveguide modes sustained in vdW materials. While most of these works\nfocused on the steady state of the EP, the spatio-temporal dynamics of EP\nformation, happening in the sub-picosecond regime, remains largely unexplored.\nHence, a direct imaging at the femtosecond-nanoscale of the EP evolution is\ncritical to the understanding of these coupled light-matter states. Here we\nreport for the first time the ultrafast and deep-subwavelength imaging of EP\nformation and propagation in WSe2 waveguides. Our method, based on a novel\nultrafast pump-probe near-field imaging, allows to directly visualize the EP\ntime evolution at room temperature. More specifically, and in agreement with\nour time dependent model, we directly observe a significantly slow EP wave\npacket group velocity of v_g~0.017c which is attributed to the bandgap\nrenormalization originating in the light coupling near the exciton transition.\nThese findings suggest that vdW materials could be used for slow light with\napplications in light storage for memory, enhanced optical nonlinearity,\nsensing and more.",
        "positive": "Embedding quantum optimization problems using AC driven quantum\n  ferromagnets: Analog quantum optimization methods, such as quantum annealing, are promising\nand at least partially noise tolerant ways to solve hard optimization and\nsampling problems with quantum hardware. However, they have thus far failed to\ndemonstrate broadly applicable quantum speedups, and an important contributing\nfactor to this is slowdowns from embedding, the process of mapping logical\nvariables to long chains of physical qubits, enabling arbitrary connectivity on\nthe short-ranged 2d hardware grid. Beyond the spatial overhead in qubit count,\nembedding can lead to severe time overhead, arising from processes where\nindividual chains ``freeze\" into ferromagnetic states at different times during\nevolution, and once frozen the tunneling rate of this single logical variable\ndecays exponentially in chain length. We show that this effect can be\nsubstantially mitigated by local AC variation of the qubit parameters as in the\nRFQA protocol (Kapit and Oganesyan, Quant. Sci. Tech. \\textbf{6}, 025013\n(2021)), through a mechanism we call Symphonic Tunneling. We provide general\narguments and substantial numerical evidence to show that AC-driven multi-qubit\ntunneling is dramatically faster than its DC counterpart, and since ST is not a\n1d-specific mechanism, this enhancement should extend to clusters of coupled\nchains as well. And unlike a uniform transverse field, in higher dimensions\nthis method cannot be efficiently simulated classically. We explore schemes to\nsynchronize the AC tones within chains to further improve performance.\nImplemented at scale, these methods could significantly improve the prospects\nfor achieving quantum scaling advantages in near-term hardware."
    },
    {
        "anchor": "Large Rashba Spin-Orbit Coupling and High-Temperature Quantum Anomalous\n  Hall Effect in Re-Intercalated Graphene/CrI$_3$ Heterostructure: In 2010, quantum anomalous Hall effect (QAHE) in graphene was proposed in the\npresence of Rashba spin-orbit coupling and ferromagnetic exchange field. After\na decade's experimental exploration, the anomalous Hall conductance can only\nreach about 0.25 in the units of $2e^2/h$, which was attributed to the tiny\nRashba spin-orbit coupling. Here, we theoretically show that Re-intercalation\nin graphene/CrI$_3$ heterostructure can not only induce sizeable Rashba\nspin-orbit coupling ($>$ 40~meV), but also open up large band gaps at valleys\n$K$ (22.2 meV) and $K' $ (30.3 meV), and a global band gap over 5.5 meV (19.5\nmeV with random Re distribution) hosting QAHE. A low-energy continuum model is\nconstructed to explain the underlying physical mechanism. We find that Rashba\nspin-orbit coupling is robust against external stress whereas a tensile strain\ncan increase the global bulk gap. Furthermore, we also show that\nRe-intercalated graphene with hexagonal boron-nitride can also realize QAHE\nwith bulk gap over 40~meV, indicating the tunability of $5d$-intercalated\ngraphene-based heterostructure. Our finding makes a great leap towards the\nexperimental realization of graphene-based QAHE, and will definitely accelerate\nthe practical application of graphene-based low-power electronics.",
        "positive": "Sensing Noncollinear Magnetism at the Atomic Scale Combining Magnetic\n  Exchange and Spin-Polarized Imaging: Storing and accessing information in atomic-scale magnets requires magnetic\nimaging techniques with single-atom resolution. Here, we show simultaneous\ndetection of the spin-polarization and exchange force, with or without the flow\nof current, with a new method, which combines scanning tunneling microscopy and\nnon-contact atomic force microscopy. To demonstrate the application of this new\nmethod, we characterize the prototypical nano-skyrmion lattice formed on a\nmonolayer of Fe/Ir(111). We resolve the square magnetic lattice by employing\nmagnetic exchange force microscopy, demonstrating its applicability to\nnon-collinear magnetic structures, for the first time. Utilizing\ndistance-dependent force and current spectroscopy, we quantify the exchange\nforces in comparison to the spin-polarization. For strongly spin-polarized\ntips, we distinguish different signs of the exchange force which we suggest\narises from a change in exchange mechanisms between the probe and a skyrmion.\nThis new approach may enable both non-perturbative readout combined with\nwriting by current-driven reversal of atomic-scale magnets."
    },
    {
        "anchor": "A two-terminal spin valve device controlled by spin-orbit torques with\n  enhanced giant magnetoresistance: We report on the combination of current-induced spin-orbit torques and giant\nmagnetoresistance in a single device to achieve all-electrical write and read\nout of the magnetization. The device consists of perpendicularly magnetized\nTbCo and Co layers separated by a Pt or Cu spacer. Current injection through\nsuch layers exerts spin-orbit torques and switches the magnetization of the Co\nlayer while the TbCo magnetization remains fixed. Subsequent current injection\nof lower amplitude senses the relative orientation of the magnetization of the\nCo and TbCo layers, which results in two distinct resistance levels for\nparallel and antiparallel alignment due to the current-in-plane giant\nmagnetoresistance effect. We further show that the giant magnetoresistance of\ndevices including a single TbCo/spacer/Co trilayer can be improved from 0.02%\nto 6% by using a Cu spacer instead of Pt. This type of devices offers an\nalternative route to a two terminal spintronic memory that can be fabricated\nwith moderate effort.",
        "positive": "(In)commensurability, scaling and multiplicity of friction in\n  nanocrystals and application to gold nanocrystals on graphite: The scaling of friction with the contact size $A$ and (in)commensurabilty of\nnanoscopic and mesoscopic crystals on a regular substrate are investigated\nanalytically for triangular nanocrystals on hexagonal substrates. The crystals\nare assumed to be stiff, but not completely rigid. Commensurate and\nincommensurate configurations are identified systematically. It is shown that\nthree distinct friction branches coexist, an incommensurate one that does not\nscale with the contact size ($A^0$) and two commensurate ones which scale\ndifferently (with $A^{1/2}$ and $A$) and are associated with various\ncombinations of commensurate and incommensurate lattice parameters and\norientations. This coexistence is a direct consequence of the two-dimensional\nnature of the contact layer, and such multiplicity exists in all geometries\nconsisting of regular lattices. To demonstrate this, the procedure is repeated\nfor rectangular geometry. The scaling of irregularly shaped crystals is also\nconsidered, and again three branches are found ($A^{1/4}, A^{3/4}, A$). Based\non the scaling properties, a quantity is defined which can be used to classify\ncommensurability in infinite as well as finite contacts. Finally, the\nconsequences for friction experiments on gold nanocrystals on graphite are\ndiscussed."
    },
    {
        "anchor": "An {\\it ab initio} study of the magnetic and electronic properties of\n  Fe, Co, and Ni nanowires on Cu(001) surface: Magnetism at the nanoscale has been a very active research area in the past\ndecades, because of its novel fundamental physics and exciting potential\napplications. We have recently performed an {\\it ab intio} study of the\nstructural, electronic and magnetic properties of all 3$d$ transition metal\n(TM) freestanding atomic chains and found that Fe and Ni nanowires have a giant\nmagnetic anisotropy energy (MAE), indicating that these nanowires would have\napplications in high density magnetic data storages. In this paper, we perform\ndensity functional calculations for the Fe, Co and Ni linear atomic chains on\nCu(001) surface within the generalized gradient approximation, in order to\ninvestigate how the substrates would affect the magnetic properties of the\nnanowires. We find that Fe, Co and Ni linear chains on Cu(001) surface still\nhave a stable or metastable ferromagnetic state. When spin-orbit coupling (SOC)\nis included, the spin magnetic moments remain almost unchanged, due to the\nweakness of SOC in 3$d$ TM chains, whilst significant orbital magnetic moments\nappear and also are direction-dependent. Finally, we find that the MAE for Fe,\nand Co remains large, i.e., being not much affected by the presence of Cu\nsubstrate.",
        "positive": "All-Electrical Spin Field Effect Transistor in van der Waals\n  Heterostructures at Room Temperature: Spintronics aims to exploit the spin degree of freedom in solid state devices\nfor data storage and information processing technologies. The fundamental\nspintronic device concepts such as creation, manipulation and detection of spin\npolarization has been demonstrated in semiconductors and spin transistor\nstructures using both the electrical and optical methods. However, an unsolved\nchallenge in the field is the realization of all electrical methods to control\nthe spin polarization and spin transistor operation at ambient temperature. For\nthis purpose, two-dimensional (2D) crystals offer a unique platform due to\ntheir remarkable and contrasting spintronic properties, such as weak spin-orbit\ncoupling (SOC) in graphene and strong SOC in molybdenum disulfide (MoS$_2$).\nHere we combine graphene and MoS$_2$ in a van der Waals heterostructure to\nrealize the electric control of the spin polarization and spin lifetime, and\ndemonstrated a spin field-effect transistor (spin-FET) at room temperature in a\nnon-local measurement geometry. We observe electrical gate control of the spin\nvalve signal due to pure spin transport and Hanle spin precession signals in\nthe graphene channel in proximity with MoS$_2$ at room temperature. We show\nthat this unprecedented control over the spin polarization and lifetime stems\nfrom the gate-tuning of the Schottky barrier at the MoS$_2$/graphene interface\nand MoS$_2$ channel conductivity leading to spin interaction with high SOC\nmaterial. The all-electrical creation, transport and control of the spin\npolarization in a spin-FET device at room temperature is a substantial step in\nthe field of spintronics. It opens a new platform for the interplay of spin,\ncharge and orbital degrees of freedom for testing a plethora of exotic physical\nphenomena, which can be key building blocks in future device architectures."
    },
    {
        "anchor": "Potential-tuned magnetic switches and half-metallicity transition in\n  zigzag graphene nanoribbons: Realizing controllable room-temperature ferromagnetism in carbon-based\nmaterials is one of recent prospects. The magnetism in graphene nanostructures\nreported previously is mostly formed near the vacancies, zigzag edges, or\nimpurities by breaking the local sublattice imbalance, though a bulk chiral\nspin-density-wave ground state is also reported at van Hove filling due to its\nperfectly nested Fermi surface. Here, combining of the first-principles and\ntight-binding model simulations, we predict a robust ferromagnetic domain lies\nbetween the inter-chain carbon atoms inside the zigzag graphene nanoribbons by\napplying a potential drop. We show that the effective zigzag edges provide the\nstrong correlation background through narrowing the band width, while the\ninternal Van Hove filling provides the strong ferromagnetic background\ninherited from the bulk. The induced ferromagnetism exhibit interesting\nswitching effect when the nominal Van Hove filling crosses the intra- and\ninter-chain region by tuning the potential drops. We further observe a robust\nhalf-metallicity transition from one spin channel to another within the same\nmagnetic phase. These novel properties provide promising ways to manipulate the\nspin degree of freedom in graphene nanostructures.",
        "positive": "Clauser-Horne inequality and decoherence in mesoscopic conductors: We analyze the effect of decoherence on the violation of the Clauser-Horne\n(CH) inequality for the full electron counting statistics in a mesoscopic\nmultiterminal conductor. Our setup consists of an entangler that emits a flux\nof entangled electrons into two conductors characterized by a scattering matrix\nand subject to decoherence. Loss of phase memory is modeled phenomenologically\nby introducing fictitious extra leads. The outgoing electrons are detected\nusing spin-sensitive electron counters. Given a certain average number of\nincoming entangled electrons, the CH inequality is evaluated as a function of\nthe numbers of detected particles and on the various quantities characterizing\nthe scattering matrix. When decoherence is turned on, we show that the amount\nof violation of the CH inequality is effectively reduced. Interestingly we find\nthat, by adjusting the parameters of the system, there exists a protected\nregion of $Q$ values for which violation holds for arbitrary strong\ndecoherence."
    },
    {
        "anchor": "Nonlinear dynamics and magneto-elasticity of nanodrums near the phase\n  transition: Nanomechanical resonances of two-dimensional (2D) materials are sensitive\nprobes for condensed-matter physics, offering new insights into magnetic and\nelectronic phase transitions. Despite extensive research, the influence of the\nspin dynamics near a second-order phase transition on the nonlinear dynamics of\n2D membranes has remained largely unexplored. Here, we investigate nonlinear\nmagneto-mechanical coupling to antiferromagnetic order in suspended\nFePS$_3$-based heterostructure membranes. By monitoring the motion of these\nmembranes as a function of temperature, we observe characteristic features in\nboth nonlinear stiffness and damping close to the N\\'{e}el temperature\n$T_{\\rm{N}}$. We account for these experimental observations with an analytical\nmagnetostriction model in which these nonlinearities emerge from a coupling\nbetween mechanical and magnetic oscillations, demonstrating that\nmagneto-elasticity can lead to nonlinear damping. Our findings thus provide\ninsights into the thermodynamics and magneto-mechanical energy dissipation\nmechanisms in nanomechanical resonators due to the material's phase change and\nmagnetic order relaxation.",
        "positive": "Induced Superconductivity in the Quantum Spin Hall Edge: Topological insulators are a newly discovered phase of matter characterized\nby a gapped bulk surrounded by novel conducting boundary states. Since their\ntheoretical discovery, these materials have encouraged intense efforts to study\ntheir properties and capabilities. Among the most striking results of this\nactivity are proposals to engineer a new variety of superconductor at the\nsurfaces of topological insulators. These topological superconductors would be\ncapable of supporting localized Majorana fermions, particles whose braiding\nproperties have been proposed as the basis of a fault-tolerant quantum\ncomputer. Despite the clear theoretical motivation, a conclusive realization of\ntopological superconductivity remains an outstanding experimental goal. Here we\npresent measurements of superconductivity induced in two-dimensional\nHgTe/HgCdTe quantum wells, a material which becomes a quantum spin Hall\ninsulator when the well width exceeds d_{C}=6.3 nm. In wells that are 7.5 nm\nwide, we find that supercurrents are confined to the one-dimensional sample\nedges as the bulk density is depleted. However, when the well width is\ndecreased to 4.5 nm the edge supercurrents cannot be distinguished from those\nin the bulk. These results provide evidence for superconductivity induced in\nthe helical edges of the quantum spin Hall effect, a promising step toward the\ndemonstration of one-dimensional topological superconductivity. Our results\nalso provide a direct measurement of the widths of these edge channels, which\nrange from 180 nm to 408 nm."
    },
    {
        "anchor": "Direct Visualization of Gigahertz Acoustic Wave Propagation in Suspended\n  Phononic Circuits: We report direct visualization of gigahertz-frequency Lamb waves propagation\nin aluminum nitride phononic circuits by transmission-mode microwave impedance\nmicroscopy (TMIM). Consistent with the finite-element modeling, the acoustic\neigenmodes in both a horn-shaped coupler and a sub-wavelength waveguide are\nrevealed in the TMIM images. Using fast Fourier transform filtering, we\nquantitatively analyze the acoustic loss of individual Lamb modes along the\nwaveguide and the power coupling coefficient between the waveguide and the\nparabolic couplers. Our work provides insightful information on the\npropagation, mode conversion, and attenuation of acoustic waves in\npiezoelectric nanostructures, which is highly desirable for designing and\noptimizing phononic devices for microwave signal processing and quantum\ninformation transduction.",
        "positive": "There is Plenty of Room for THz Tunneling Electron Devices Beyond the\n  Transit Time Limit: The traditional transmission coefficient present in the original Landauer\nformulation, which is valid for quasi-static scenarios with working frequencies\nbelow the inverse of the electron transit time, is substituted by a novel\ntime-dependent displacement current coefficient valid for frequencies above\nthis limit. Our model captures in a simple way the displacement current\ncomponent of the total current, which at frequencies larger than the inverse of\nthe electron transit time can be more relevant than the particle component. The\nproposed model is applied to compute the response of a resonant tunneling diode\nfrom 10$\\,$GHz up to 5$\\,$THz. We show that tunneling electron devices are\nintrinsically nonlinear at such high frequencies, even under small-signal\nconditions, due to memory effects related to the displacement current. We show\nthat these intrinsic nonlinearities (anharmonicities) represent an advantage,\nrather than a drawback, as they open the path for tunneling devices in many THz\napplications, and avoid further device downscaling."
    },
    {
        "anchor": "Phonon Transport in Graphene: Properties of phonons - quanta of the crystal lattice vibrations - in\ngraphene have attracted strong attention of the physics and engineering\ncommunities. Acoustic phonons are the main heat carriers in graphene near room\ntemperature while optical phonons are used for counting the number of atomic\nplanes in Raman experiments with few-layer graphene. It was shown both\ntheoretically and experimentally that transport properties of phonons, i.e.\nenergy dispersion and scattering rates, are substantially different in the\nquasi two-dimensional system such as graphene compared to basal planes in\ngraphite or three-dimensional bulk crystals. The unique nature of\ntwo-dimensional phonon transport translates to unusual heat conduction in\ngraphene and related materials. In this review we outline different theoretical\napproaches developed for phonon transport in graphene, discuss contributions of\nthe in-plane and cross-plane phonon modes and provide comparison with available\nexperimental thermal conductivity data. Particular attention is given to\nanalysis of recent theoretical results for the phonon thermal conductivity of\ngraphene and few-layer graphene, and the effects of the strain, defects and\nisotopes on the phonon transport in these systems.",
        "positive": "Local strain engineering in atomically thin MoS2: Tuning the electronic properties of a material by subjecting it to strain\nconstitutes an important strategy to enhance the performance of semiconducting\nelectronic devices. Using local strain, confinement potentials for excitons can\nbe engineered, with exciting possibilities for trapping excitons for quantum\noptics and for efficient collection of solar energy. Two-dimensional materials\nare able to withstand large strains before rupture, offering a unique\nopportunity to introduce large local strains. Here, we study atomically thin\nMoS2 layers with large local strains of up to 2.5% induced by controlled\ndelamination from a substrate. Using simultaneous scanning Raman and\nphotoluminescence imaging, we spatially resolve a direct bandgap reduction of\nup to 90 meV induced by local strain. We observe a funnel effect in which\nexcitons drift hundreds of nanometers to lower bandgap regions before\nrecombining, demonstrating exciton confinement by local strain. The\nobservations are supported by an atomistic tight-binding model developed to\npredict the effect of inhomogeneous strain on the local electronic states in\nMoS2. The possibility of generating large strain-induced variations in exciton\ntrapping potentials opens the door for a variety of applications in atomically\nthin materials including photovoltaics, quantum optics and two-dimensional\noptoelectronic devices."
    },
    {
        "anchor": "Gap and channelled plasmons in tapered grooves: a review: Tapered metallic grooves have been shown to support plasmons --\nelectromagnetically coupled oscillations of free electrons at metal-dielectric\ninterfaces -- across a variety of configurations and V-like profiles. Such\nplasmons may be divided into two categories: gap-surface plasmons (GSPs) that\nare confined laterally between the tapered groove sidewalls and propagate\neither along the groove axis or normal to the planar surface, and channelled\nplasmon polaritons (CPPs) that occupy the tapered groove profile and propagate\nexclusively along the groove axis. Both GSPs and CPPs exhibit an assortment of\nunique properties that are highly suited to a broad range of cutting-edge\nnanoplasmonic technologies, including ultracompact photonic circuits,\nquantum-optics components, enhanced lab-on-a-chip devices, efficient\nlight-absorbing surfaces and advanced optical filters, while additionally\naffording a niche platform to explore the fundamental science of plasmon\nexcitations and their interactions. In this Review, we provide a research\nstatus update of plasmons in tapered grooves, starting with a presentation of\nthe theory and important features of GSPs and CPPs, and follow with an overview\nof the broad range of applications they enable or improve. We cover the\ntechniques that can fabricate tapered groove structures, in particular\nhighlighting wafer-scale production methods, and outline the various photon-\nand electron-based approaches that can be used to launch and study GSPs and\nCPPs. We conclude with a discussion of the challenges that remain for further\ndeveloping plasmonic tapered-groove devices, and consider the future directions\noffered by this select yet potentially far-reaching topic area.",
        "positive": "Stacking in incommensurate graphene/hexagonal-boron-nitride\n  heterostructures based on ab initio study of interlayer interaction: The interlayer interaction in graphene/boron-nitride heterostructures is\nstudied using density functional theory calculations with the correction for\nvan der Waals interactions. It is shown that the use of the experimental\ninterlayer distance allows to describe the potential energy surface at the\nlevel of more accurate but expensive computational methods. On the other hand,\nit is also demonstrated that the dependence of the interlayer interaction\nenergy on the relative in-plane position of the layers can be fitted with high\naccuracy by a simple expression determined by the system symmetry. The use of\nonly two independent parameters in such an approximation suggests that various\nphysical properties of flat graphene/boron-nitride systems are interrelated and\ncan be expressed through these two parameters. Here we estimate some of the\ncorresponding physical properties that can be accessed experimentally,\nincluding the correction to the period of the Moir\\'{e} superstructure for the\nhighly incommensurate ground state of graphene/boron-nitride bilayer coming\nfrom the interlayer interaction, width of stacking dislocations in slightly\nincommensurate systems of boron nitride on stretched graphene and shear mode\nfrequencies for commensurate graphene/boron-nitride systems, such as a flake on\na layer. We propose that the commensurate-incommensurate phase transition can\nbe observed in boron nitride on stretched graphene and experimental\nmeasurements of the corresponding critical strain can be also used to get an\ninsight into graphene/boron-nitride interactions."
    },
    {
        "anchor": "Phonon-induced dephasing in quantum dot-cavity QED: Limitations of the\n  polaron master equation: A semiconductor quantum dot (QD) embedded within an optical microcavity is a\nsystem of fundamental importance within quantum information processing. The\noptimization of quantum coherence is crucial in such applications, requiring an\nin-depth understanding of the relevant decoherence mechanisms. We provide\nherein a critical review of prevalent theoretical treatments of the QD-cavity\nsystem coupled to longitudinal acoustic phonons, comparing predictions against\na recently obtained exact solution. Within this review we consider a range of\ntemperatures and exciton-cavity coupling strengths. Predictions of the polaron\nNakajima-Zwanzig (NZ) and time-convolutionless (TCL) master equations, as well\nas a variation of the former adapted for adiabatic continuous wave excitation\n(CWE), are compared against an asymptotically exact solution based upon\nTrotter's decomposition (TD) theorem. The NZ and TCL implementations, which\napply a polaron transformation to the Hamiltonian and subsequently treat the\nexciton-cavity coupling to second order, do not offer a significant improvement\naccuracy relative to the polaron transformation alone. The CWE adaptation\nprovides a marked improvement, capturing the broadband features of the\nabsorption spectrum (not present in NZ and TCL implementations). We attribute\nthis difference to the effect of the Markov approximation, and particularly its\nunsuitability in pulsed excitation regime. Even the CWE adaptation, however,\nbreaks down in the regime of high temperature ($50K$) and strong exciton-cavity\ncoupling ($g \\gtrsim 0.2$ meV). The TD solution is of comparable computational\ncomplexity to the above-mentioned master equation approaches, yet remains\naccurate at higher temperatures and across a broad range of exciton-cavity\ncoupling strengths (at least up to $g=1.5$ meV).",
        "positive": "Magnetic Response in a Zigzag Carbon Nanotube: Magnetic response of interacting electrons in a zigzag carbon nanotube\nthreaded by a magnetic flux is investigated within a Hartree-Fock mean field\napproach. Following the description of energy spectra for both non-interacting\nand interacting cases we analyze the behavior of persistent current in\nindividual branches of a nanotube. Our present investigation leads to a\npossibility of getting a filling-dependent metal-insulator transition in a\nzigzag carbon nanotube."
    },
    {
        "anchor": "Ground State thermodynamic and response properties of electron gas in a\n  strong magnetic and electric field: Exact analytical solutions for a\n  conventional semiconductor and for Graphene: Consequences of an exceedingly strong electric field (E field) on the ground\nstate energetics and transport properties of a 2D spinless electron gas in a\nperpendicular magnetic field (a Quantum Hall Effect (QHE) configuration) are\ninvestigated to all orders in the fields. For a conventional semiconductor, we\nfind fractional values of the Hall conductivity and some magnetoelectric\ncoefficients for certain values of E and B fields that do not result from\ninteractions or impurities, but are a pure consequence of a strong enough\nin-plane E field. We also determine analytically the ground state energy, and\nresponse properties such as magnetization and polarization as functions of the\nelectromagnetic field in the strong E field limit. In the case of Graphene, we\nobtain more complex behaviors leading to the possibility of irrational Hall\nvalues. The results are also qualitatively discussed in connection to various\nmechanisms for the QHE-breakdown.",
        "positive": "Quantum Dynamics of Pseudospin Solitons in Double-Layer Quantum Hall\n  Systems: Pseudospin solitons in double-layer quantum Hall systems can be introduced by\na magnetic field component coplanar with the electrons and can be pinned by\napplying voltages to external gates. We estimate the temperature below which\ndepinning occurs predominantly via tunneling and calculate low-temperature\ndepinning rates for realistic geometries. We discuss the local changes in\ncharge and current densities and in spectral functions that can be used to\ndetect solitons and observe their temporal evolution."
    },
    {
        "anchor": "Enhanced thermoelectric properties in phosphorene nanorings: Using the tight-binding approach, we investigate the thermoelectric (TE)\nproperties of rectangular phosphorene nanorings for both symmetrically and\nasymmetrically attaching to phosphorene nanoribbon leads. We design our\nphosphorene-based nanostructures to enhance the TE performance in the absence\nand the presence of perpendicular magnetic fields. Our results show that when\nzigzag phosphorene nanoribbons (ZPNRs) are coupled symmetrically to rectangular\nrings, a comparatively large band gap is induced in the electronic conductance\ndue to the suppression of the contribution of edge states. This gives rise to a\nremarkable increase in the thermopower response compared to the case of\npristine ZPNRs. More intriguingly, we found that though the maximum power\nfactor in this system is about the same as the one for its ZPNR counterpart,\nthe much smaller electronic thermal conductance of this phosphorene-based\nnanostructure can remarkably contribute to the improvement of the figure of\nmerit. Also, we found that the symmetry/asymmetry of our designed\nnanostructures, the geometrical characteristics of the ring, and the magnetic\nflux are three important factors that control the thermoelectric properties of\nphosphorene quantum rings. Our numerical calculations show that by changing the\nmagnetic flux through the nanoring, a drastic increase in the thermopower is\nobserved near an antiresonance point. We demonstrate the tunability of the\nthermopower and the possibility to switch on and off the TE response of\nphosphorene nanorings with the magnetic flux. Moreover, for asymmetric\nconnection configurations with armchair-edged leads, we found that though the\nthermopower is almost intact, a remarkable reduction of the electronic thermal\nconductance can lead to a notable improvement in the figure of merit. Our\nresults suggest phosphorene nanorings as promising candidate nanostructures for\nTE applications.",
        "positive": "Spin motive force induced by Rashba interaction in the strong sd\n  coupling regime: Spin motive force induced by the Rashba interaction in the presence of strong\nsd interaction between conduction electron and localized spin is theoretically\nstudied. The motive force is calculated by evaluating the time-derivative of\nthe current density on the basis of microscopic formalism. It is shown that\nthere are two motive forces, one proportional to $\\EvR\\times\\dot{\\nv}$, the\nother, perpendicular component, proportional to\n$\\EvR\\times(\\nv\\times\\dot{\\nv})$, where $\\EvR$ and $\\nv$ are the Rashba\nelectric field and localized spin direction, respectively. The second type\narises in the strong sd coupling regime from the spin relaxation. The\nappearance of perpendicular component from the spin relaxation is understood\nfrom the analogy with the current-induced torques. In the case of domain wall\nmotion, the two contributions to the spin motive force are the same order of\nmagnitude, while the first term dominates in the case of precession of uniform\nmagnetization. Our result explains appearance of the perpendicular component in\nthe weak sd coupling limit, recently discussed in the context of spin damping\nmonopole. Detection of AC voltage induced by the precession of uniform\nmagnetization serves as a experimental evidence of the Rashba interaction in\nfilms and wires."
    },
    {
        "anchor": "Nanoelectromechanical resonators from high-T$_c$ superconducting\n  crystals of Bi$_2$Sr$_2$Ca$_1$Cu$_2$O$_{8+\u03b4}$: In this report, we present nanoelectromechanical resonators fabricated with\nthin exfoliated crystals of a high-T$_c$ cuprate superconductor\nBi$_2$Sr$_2$Ca$_1$Cu$_2$O$_{8+\\delta}$. The mechanical readout is performed by\ncapacitively coupling their motion to a coplanar waveguide microwave cavity\nfabricated with a superconducting alloy of molybdenum-rhenium. We demonstrate\nmechanical frequency tunability with external dc-bias voltage, and quality\nfactors up to 36600. Our spectroscopic and time-domain measurements show that\nmechanical dissipation in these systems is limited by the contact resistance\narising from resistive outer layers. The temperature dependence of dissipation\nindicates the presence of tunneling states, further suggesting that their\nintrinsic performance could be as good as other two-dimensional atomic crystals\nsuch as graphene.",
        "positive": "Revisiting Coulomb diamond signatures in quantum Hall interferometers: Coulomb diamonds are the archetypal signatures of Coulomb blockade, a\nwell-known charging effect mainly observed in nanometer-sized \"electronic\nislands\" tunnel-coupled with charge reservoirs. Here, we identify apparent\nCoulomb diamond features in the scanning gate spectroscopy of a quantum point\ncontact carved out of a semiconductor heterostructure, in the quantum Hall\nregime. Varying the scanning gate parameters and the magnetic field, the\ndiamonds are found to smoothly evolve to checkerboard patterns. To explain this\nsurprising behavior, we put forward a model which relies on the presence of a\nnanometer-sized Fabry-P\\'erot quantum Hall interferometer at the center of the\nconstriction with tunable tunneling paths coupling the central part of the\ninterferometer to the quantum Hall channels running along the device edges.\nBoth types of signatures, diamonds and checkerboards, and the observed\ntransition, are reproduced by simply varying the interferometer size and the\ntransmission probabilities at the tunneling paths. The new proposed\ninterpretation of diamond phenomenology will likely lead to revisit previous\ndata, and opens the way towards engineering more complex interferometric\ndevices with nanoscale dimensions."
    },
    {
        "anchor": "Graphene membranes and the Dirac-Born-Infeld action: We propose the use of the Dirac-Born-Infeld action in the phenomenological\ndescription of graphene sheet dynamics and interactions. Both the electronic\nproperties of the Dirac fermions and the overall dynamics can be incorporated\ninto this model. Classical static configurations, as well as quantum\nfluctuations of the membrane degrees of freedom can be studied in this\nframework. This makes it an interesting tool for Casimir physics and novel QED\nprocesses.",
        "positive": "Phonon-mediated decoherence in triple quantum dot interferometers: We investigate decoherence in a triple quantum dot in ring configuration in\nwhich one dot is coupled to a damped phonon mode, while the other two dots are\nconnected to source and drain, respectively. In the absence of decoherence,\nsingle electron transport may get blocked by an electron falling into a\nsuperposition decoupled from the drain and known as dark state. Phonon-mediated\ndecoherence affects this superposition and leads to a finite current. We study\nthe current and its shot noise numerically within a master equation approach\nfor the electrons and the dissipative phonon mode. A polaron transformation\nallows us to obtain a reduced equation for only the dot electrons which\nprovides analytical results in agreement with numerical ones."
    },
    {
        "anchor": "Electronic Structure of Disclinated Graphene in an Uniform Magnetic\n  Field: The electronic structure in the vicinity of the 1-heptagonal and 1-pentagonal\ndefects in the carbon graphene plane is investigated. Using a continuum gauge\nfield-theory model the local density of states around the Fermi energy is\ncalculated for both cases. In this model, the disclination is represented by an\nSO(2) gauge vortex and corresponding metric follows from the elasticity\nproperties of the graphene membrane. To enhance the interval of energies, a\nself-consistent perturbation scheme is used. The Landau states are investigated\nand compared with the predicted values.",
        "positive": "Dynamical Coulomb blockade of multiple Andreev reflections: We analyze the dynamical Coulomb blockade of multiple Andreev reflections\n(MAR) in a superconducting quantum point contact coupled to a macroscopic\nimpedance. We find that at very low transmission the blockade scales as $n^2$\nwith $n = {Int}(2\\Delta/eV)$, where $V$ is the bias voltage and $\\Delta$ is the\nsuperconducting gap, as it would correspond to the occurrence of \"shots\" of\ncharge $ne$. For higher transmission the blockade is reduced both due to Pauli\nprinciple and to elastic renormalization of the MAR probability, and for\ncertain voltage regions it may even become an \"antiblockade\", i.e. the current\nis enhanced due to the coupling with the electromagnetic environment."
    },
    {
        "anchor": "High-yield exfoliation of MoS2 nanosheets by a novel spray technique and\n  the importance of soaking and surfactants: Liquid-phase exfoliation of two-dimensional materials is very attractive for\nlarge-scale applications. Although used extensively, isolating MoS2 layers\n(<10) with high efficiency is reported to be extremely difficult. Further, the\nimportance of soaking has not yet been studied, and the surfactants' role in\nstabilizing MoS2 nanosheets is poorly understood1. Herein, we report a novel\napproach to exfoliating large quantities of MoS2 via high-pressure (HP)\nliquid-phase exfoliation (LPE) in deionized (DI) water. 4 to 7 layers of MoS2\nnanosheets were obtained from 60 days-soaked samples and they were found to be\nstable in solvents for periods of up to six months. Studies on the effect of\nthree surfactants, namely sodium dodecyl benzenesulfonate (SDBS), sodium\ncholate (SC), and tetra-butyl ammonium bromide (TBAB), indicate that\nexfoliation of MoS2 nanosheets in SDBS is highly efficient than the other two\nsurfactants. The estimated yield reaches up to 7.25%, with a nanosheet\nconcentration of 1.45 mg/ml, which is one of the highest ever reported. Our\nstudies also suggest that the nanosheets' concentration and the lateral size\ndepend on exfoliation cycles, applied pressure and surfactant concentration.\nHydrogen evolution reaction (HER) and ion-transport study show that the\nnanosheets prepared by our method are stable in an acidic medium and free from\nsurfactants. A high hydrogen evolution rate of 30.13 mmol g-1 h-1 was estimated\nunder ambient laboratory conditions.",
        "positive": "Magnon transport through a quantum dot: Conversion to electronic spin\n  and charge currents: We consider a single-level quantum dot coupled to magnetic insulators\n(magnonic reservoirs) and magnetic metals (electronic reservoirs). The whole\nsystem is in an external magnetic field. In a general case, the system includes\ntwo magnonic and two electronic reservoirs, but we also present results for\nsome specific situations, where only two or three reservoirs are effectively\nconnected to the dot. The main objective is the analysis of the conversion of\nmagnon current to electronic spin and charge currents, and {\\it vice versa}. We\nconsider the limiting case of large Coulomb energy in the dot (Coulomb\nblockade), as well as the case when the Coulomb energy is finite and double\noccupancy is allowed."
    },
    {
        "anchor": "Microscopic metallic air-bridge arrays for connecting quantum devices: We present a single-exposure fabrication technique for a very large array of\nmicroscopic air-bridges using a tri-layer resist process with electron-beam\nlithography. The technique is capable of forming air-bridges with strong\nmetal-metal or metal-substrate connections. This was demonstrated by its\napplication in an electron tunnelling device consisting of 400 identical\nsurface gates for defining quantum wires, where the air-bridges are used as\nsuspended connections for the surface gates. This technique enables us to\ncreate a large array of uniform one-dimensional channels that are open at both\nends. In this article, we outline the details of the fabrication process,\ntogether with a study and the solution of the challenges present in the\ndevelopment of the technique, which includes the use of water-IPA (isopropyl\nalcohol) developer, calibration of resist thickness and numerical simulation of\nthe development.",
        "positive": "$\u03bd=2$ Bilayer Quantum Hall System in Tilted Magnetic Field: We report on a theoretical study of $\\nu=2$ bilayer quantum Hall systems with\na magnetic field that has a component parallel to the layers. As in the $\\nu=1$\ncase, interlayer phase coherence is closely coupled to electron correlations\nand the Aharonov-Bohm phases introduced by a parallel magnetic field can have a\nstrong influence on the ground state of the system. We find that response of a\n$\\nu=2$ system to a parallel field is more subtle than that of a $\\nu=1$ system\nbecause of the interplay between spin and layer degrees of freedom. There is no\ncommensurate-incommensurate transition as the parallel field is increased.\nInstead, we find a new phase transition which can occur in fixed parallel field\nas the interlayer bias potential is varied. The transition is driven by the\ncompetition between canted antiferromagnetic order and interlayer phase\ncoherence in the presence of the parallel field. We predict a strong\nsingularity in the differential capacitance of the bilayer which can be used to\ndetect the phase transition."
    },
    {
        "anchor": "Observation of impedance oscillations in single walled carbon nanotube\n  bundles excited by high frequency signals: We report experimental observation of impedance oscillations in single-walled\ncarbon nanotubes measured from 100 MHz to 65 GHz on coplanar wave guides and a\npower law dependence of the differential conductance with bias voltage. From\nthe crossover of the real and imaginary parts of the complex impedance observed\nin the range of 10 GHz, we estimate a long lifetime of 15 ps that can support\nthe claim of ballistic transport. By measuring the scattering parameters at\nhigh-frequencies of a few aligned single-walled bundles at low temperatures we\nshow that, this observation is strongly influenced by the number of tubes\navailable.",
        "positive": "Floating of critical states and the QH to insulator transition: The transition from the quantum Hall state to the insulator is considered for\nnon-interacting electrons in a two-dimensional disordered lattice model with\nperpendicular magnetic field. Using correlated random disorder potentials the\nfloating up of the critical states can be observed in a similar way as in the\ncontinuum model. Thus, the peculiar behaviour of the lattice models reported\npreviously originates in the special choice of uncorrelated random disorder\npotentials."
    },
    {
        "anchor": "Modal frustration and periodicity breaking in artificial spin ice: Here an artificial spin ice (ASI) lattice is introduced that exhibits unique\nIsing and non-Ising behavior under specific field switching protocols because\nof the inclusion of coupled nanomagnets into the unit cell. In the Ising\nregime, a magnetic switching mechanism that generates a uni- or bimodal\ndistribution of states dependent on the alignment of the field is demonstrated\nwith respect to the lattice unit cell. In addition, a method for generating a\nplethora of randomly distributed energy states across the lattice, consisting\nof Ising and Landau states, is investigated through magnetic force microscopy\nand micromagnetic modeling. We demonstrate that the dispersed energy\ndistribution across the lattice is a result of the intrinsic design and can be\nfinely tuned through control of the incident angle of a critical field. The\npresent manuscript explores a complex frustrated environment beyond the\n16-vertex Ising model for the development of novel logic-based technologies.",
        "positive": "Fermi arc reconstruction at the interface of twisted Weyl semimetals: Three-dimensional Weyl semimetals have pairs of topologically protected Weyl\nnodes, whose projections onto the surface Brillouin zone are the end points of\nzero energy surface states called Fermi arcs. At the endpoints of the Fermi\narcs, surface states extend into and are hybridized with the bulk. Here, we\nconsider a two-dimensional junction of two identical Weyl semimetals whose\nsurfaces are twisted with respect to each other and tunnel-coupled. Confining\nourselves to commensurate angles (such that a larger unit cell preserves a\nreduced translation symmetry at the interface) enables us to analyze arbitrary\nstrengths of the tunnel-coupling. We study the evolution of the Fermi arcs at\nthe interface, in detail, as a function of the twisting angle and the strength\nof the tunnel-coupling. We show unambiguously that in certain parameter\nregimes, all surface states decay exponentially into the bulk, and the Fermi\narcs become Fermi loops without endpoints. We study the evolution of the `Fermi\nsurfaces' of these surface states as the tunnel-coupling strengths vary. We\nshow that changes in the connectivity of the Fermi arcs/loops have interesting\nsignatures in the optical conductivity in the presence of a magnetic field\nperpendicular to the surface."
    },
    {
        "anchor": "Anomalous-Nernst and anisotropic magnetoresistive heating in a lateral\n  spin valve: We measured the anomalous-Nernst effect and anisotropic magnetoresistive\nheating in a lateral multiterminal Permalloy/Copper spin valve using\nall-electrical lock-in measurements. To interpret the results, a\nthree-dimensional thermoelectric finite-element-model is developed. Using this\nmodel, we extract the heat profile which we use to determine the anomalous\nNernst coefficient of Permalloy Rn=0.13 and also determine the maximum angle of\ntheta=8 degrees of the magnetization prior to the switching process when an\nopposing non-collinear 10$^{\\circ}$ magnetic field is applied.",
        "positive": "Low-energy effective theory in the bulk for transport in a topological\n  phase: We construct a low-energy effective action for a two-dimensional\nnon-relativistic topological (i.e.\\ gapped) phase of matter in a continuum,\nwhich completely describes all of its bulk electrical, thermal, and\nstress-related properties in the limit of low frequencies, long distances, and\nzero temperature, without assuming either Lorentz or Galilean invariance. This\nis done by generalizing Luttinger's approach to thermoelectric phenomena, via\nthe introduction of a background vielbein (i.e.\\ gravitational) field and spin\nconnection a la Cartan, in addition to the electromagnetic vector potential, in\nthe action for the microscopic degrees of freedom (the matter fields).\nCrucially, the geometry of spacetime is allowed to have timelike and spacelike\ntorsion. These background fields make all natural invariances--- under U(1)\ngauge transformations, translations in both space and time, and spatial\nrotations---appear locally, and corresponding conserved currents and the stress\ntensor can be obtained, which obey natural continuity equations. On integrating\nout the matter fields, we derive the most general form of a local bulk induced\naction to first order in derivatives of the background fields, from which\nthermodynamic and transport properties can be obtained. We show that the gapped\nbulk cannot contribute to low-temperature thermoelectric transport other than\nthe ordinary Hall conductivity; the other thermoelectric effects (if they\noccur) are thus purely edge effects. The coupling to \"reduced\" spacelike\ntorsion is found to be absent in minimally-coupled models, and using a\ngeneralized Belinfante stress tensor, the stress response to time-dependent\nvielbeins (i.e.\\ strains) is the Hall viscosity, which is robust against\nperturbations and related to the spin current as in earlier work."
    },
    {
        "anchor": "Internal structure of hexagonal skyrmion lattices in cubic helimagnets: We have utilised a high spatial resolution imaging method, Differential Phase\nContrast (DPC) performed in a scanning transmission electron microscope (STEM),\nfor precise measurement of the magnetic induction distribution in skyrmion\nstates in noncentrosymmetric magnetically ordered materials. Applied to\ninvestigate the internal structure of hexagonal skyrmion lattice cells,\nstabilised by an out-plane applied magnetic field in an FeGe nanowedge\nspecimen, mapping of the in-plane component of magnetic induction has yielded\n\"average\" skyrmion profiles and observation of internal six-fold symmetry. With\nincreasing field strength, the diameter of \"average\" skyrmion cores was\nobserved to decrease accompanied by a non-linear variation of the lattice\nperiodicity. Variations in structure for individual skyrmions were studied\nutilising an advanced DPC detection scheme with a variety of symmetry lowering\ndistortions being observed. Our observations are consistent with a theoretical\nphenomenological model, which has predicted the structure of hexagonal skyrmion\nlattice cells and also that twisting states near to the material surfaces\nprovide a basis for energetic stabilisation of the skyrmion lattice over the\nconical phase. There was good agreement with experiment for predictions of bulk\nskyrmion structure and their response (core-size & lattice periodicity\nvariation) to an applied field.",
        "positive": "Breit-Wigner-Fano lineshapes in Raman spectra of graphene: Excitation of electron-hole pairs in the vicinity of the Dirac cone by the\nCoulomb interaction gives rise to an asymmetric Breit-Wigner-Fano lineshape in\nthe phonon Raman spectra in graphene. This asymmetric lineshape appears due to\nthe interference effect between the phonon spectra and the electron-hole pair\nexcitation spectra. The calculated Breit-Wigner-Fano asymmetric factor 1/qBWF\nas a function of the Fermi energy shows a V-shaped curve with a minimum value\nat the charge neutrality point and gives good agreement with the experimental\nresult."
    },
    {
        "anchor": "Two-electron n-p double quantum dots in carbon nanotubes: We consider electron states in n-p double quantum dots defined in a\nsemiconducting carbon nanotube (CNT) by an external potential. We describe\nformation of extended single-electron orbitals originating from the conduction\nand valence bands confined in a minimum and a maximum of the external\npotential, respectively. We solve the problem of a confined electron pair using\nan exact diagonalization method within the tight-binding approach, which allows\nfor a straightforward treatment of the conduction and valence band states,\nkeeping an exact account for the intervalley scattering mediated by the atomic\ndefects and the electron-electron interaction. The exchange interaction - which\nin the unipolar double dots is nearly independent of the axial magnetic field\n(B) and forms singlet-like and triplet-like states - in the n-p system appears\nonly for selected states and narrow intervals of B. In particular the\nground-state energy level of a n-p double dot is not split by the exchange\ninteraction and remains four-fold degenerate at zero magnetic field also for a\nstrong tunnel coupling between the dots.",
        "positive": "Intervalley coupling by quantum dot confinement potentials in monolayer\n  transition metal dichalcogenides: Monolayer transition metal dichalcogenides (TMDs) offer new opportunities for\nrealizing quantum dots (QDs) in the ultimate two-dimensional (2D) limit. Given\nthe rich control possibilities of electron valley pseudospin discovered in the\nmonolayers, this quantum degree of freedom can be a promising carrier of\ninformation for potential quantum spintronics exploiting single electrons in\nTMD QDs. An outstanding issue is to identify the degree of valley\nhybridization, due to the QD confinement, which may significantly change the\nvalley physics in QDs from its form in the 2D bulk. Here we perform a\nsystematic study of the intervalley coupling by QD confinement potentials on\nextended TMD monolayers. We find that the intervalley coupling in such geometry\nis generically weak due to the vanishing amplitude of the electron wavefunction\nat the QD boundary, and hence valley hybridization shall be well quenched by\nthe much stronger spin-valley coupling in monolayer TMDs and the QDs can well\ninherit the valley physics of the 2D bulk. We also discover sensitive\ndependence of intervalley coupling strength on the central position and the\nlateral length scales of the confinement potentials, which may possibly allow\ntuning of intervalley coupling by external controls"
    },
    {
        "anchor": "Mesoscopic Spin Tunneling in Molecular Crystals: The phenomenon of Quantum Tunneling of Mesoscopic Spins is reviewed in the\nlight of the behavior of the archetype of these systems: the molecular complex\nMn12-ac. Most observations can be understood in the framework of the reduced\nHilbert space dimension 2S+1=21. Due to the large spin S=10, the energy barrier\npreventing spin rotation is large, and as a consequence, quantum relaxation is\nvery slow. The application of a magnetic field of a few Tesla below 1 K allows\nto observe tunneling (i) between the states m=-10 and m=10-n with n=8 to 11 if\nthe field is longitudinal, or (ii) between the two ground-states m~-10 and m~10\nif the field is transverse. The crossover temperature between ground-state and\nthermally assisted tunneling in a longitudinal field extrapolates in zero field\nat ~1.7 K. The observation of square root relaxation at\nshort-times/low-temperatures and of exponential relaxation at\nlong-times/high-temperatures, as observed previously above 1.5 K, confirms the\nimportant role of the spin bath dynamics which is out of equilibrium in the\nfirst regime and at equilibrium in the second one. In a second part of this\npaper a new molecule, so-called V15, with resultant spin S=1/2 is investigated.\nContrary to high spin molecules, the energy barrier of low spin molecules is\nsmall or null, and the splitting between the symmetrical and anti-symmetrical\nstates is sufficiently large to allow spin-phonon transitions during spin\nrotation. In low spin molecules the coupling to the environment is quite\ndifferent from the one found in large spin molecules in low fields.",
        "positive": "Two Electron Quantum Dot - A Variational Treatment For The Ground State: A variational treatment for a two-electron quantum dot (the artificial helium\natom) is proposed which leads to exact answer for the ground state energy.\nDepending on the magnetic field value the singlet-triplet and triplet-triplet\ntransitions of the ground state take place, which are captured in our solution.\nUsing the same variational technique we find corrections to wave function and\nenergy and the transition field strengths in a realistic dot where electron\nwave function has a finite extent in the direction perpendicular to the x-y\nplane in which usually 2-D dot electrons are confined. Using the variational\nwave function we show that photoemission cross-section as a function of\nmagnetic field has sharp discontinuities, which can be used for experimental\nverification of the singlet-triplet transitions."
    },
    {
        "anchor": "Reduced quantum electrodynamics in curved space: An approach that has been given promising results concerning investigations\non the physics of graphene is the so-called reduced quantum electrodynamics. In\nthis work we consider the natural generalization of this formalism to curved\nspaces. We employ the local momentum space representation. We discuss the\nvalidity of the Ward identity and study one-loop diagrams in detail. We show\nthat the one-loop beta function is zero. As an application, we calculate the\none-loop optical conductivity of graphene by taking into account curvature\neffects which can be incorporated locally. In addition, we demonstrate how such\neffects may contribute to the conductivity. Furthermore, and quite\nunexpectedly, our calculations unveil the emergence of a curvature-induced\neffective chemical potential contribution in the optical conductivity.",
        "positive": "Theoretical and experimental investigations of Coulomb blockade in\n  coupled quantum dot systems: Two strongly coupled quantum dots are theoretically and experimentally\ninvestigated. In the conductance measurements of a GaAs based low-dimensional\nsystem additional features to the Coulomb blockade have been detected at low\ntemperatures. These regions of finite conductivity are compared with\ntheoretical investigations of a strongly coupled quantum dot system and good\nagreement of the theoretical and the experimental results has been found."
    },
    {
        "anchor": "Floquet higher-order Weyl and nexus semimetals: This work reports the general design and characterization of two exotic,\nanomalous nonequilibrium topological phases. In equilibrium systems, the Weyl\nnodes or the crossing points of nodal lines may become the transition points\nbetween higher-order and first-order topological phases defined on\ntwo-dimensional slices, thus featuring both hinge Fermi arc and surface Fermi\narc. We advance this concept by presenting a strategy to obtain, using\ntime-sequenced normal insulator phases only, Floquet higher-order Weyl\nsemimetals and Floquet higher-order nexus semimetals, where the concerned\ntopological singularities in the three-dimensional Brillouin zone border\nanomalous two-dimensional higher-order Floquet phases. The fascinating\ntopological phases we obtain are previously unknown and can be experimentally\nstudied using, for example, a three-dimensional lattice of coupled ring\nresonators.",
        "positive": "Hierarchical tensile structures with ultralow mechanical dissipation: Structural hierarchy is found in myriad biological systems and has improved\nman-made structures ranging from the Eiffel tower to optical cavities.\nHierarchical metamaterials utilize structure at multiple size scales to realize\nnew and highly desirable properties which can be strikingly different from\nthose of the constituent materials. In mechanical resonators whose rigidity is\nprovided by static tension, structural hierarchy can reduce the dissipation of\nthe fundamental mode to ultralow levels due to an unconventional form of soft\nclamping. Here, we apply hierarchical design to silicon nitride nanomechanical\nresonators and realize binary tree-shaped resonators with quality factors as\nhigh as $10^9$ at 107 kHz frequency, reaching the parameter regime of levitated\nparticles. The resonators' thermal-noise-limited force sensitivities reach\n$740\\ \\mathrm{zN/\\sqrt{Hz}}$ at room temperature and $\\mathrm{90\\\nzN/\\sqrt{Hz}}$ at 6 K, surpassing state-of-the-art cantilevers currently used\nfor force microscopy. We also find that the self-similar structure of binary\ntree resonators results in fractional spectral dimensions, which is\ncharacteristic of fractal geometries. Moreover, we show that the hierarchical\ndesign principles can be extended to 2D trampoline membranes, and we fabricate\nultralow dissipation membranes suitable for interferometric position\nmeasurements in Fabry-P\\'erot cavities. Hierarchical nanomechanical resonators\nopen new avenues in force sensing, signal transduction and quantum\noptomechanics, where low dissipation is paramount and operation with the\nfundamental mode is often advantageous."
    },
    {
        "anchor": "Weak Localization and Weak Antilocalization in Double-Gate a-InGaZnO\n  Thin-Film Transistors: We demonstrate manipulation of quantum interference by controlling the\ncompetitions between weak localization (WL) and weak antilocalization (WAL) via\nvariation of the gate voltages of double- gate amorphous InGaZnO thin-film\ntransistors. Our study unveils the full profile of an intriguing universal\ndependence of the respective WL and WAL contributions on the channel\nconductivity. This universality is discovered to be robust against interface\ndisorder.",
        "positive": "Chiral surface twists and skyrmion stability in nanolayers of cubic\n  helimagnets: Lorentz transmission electron microscopy (LTEM) investigations of modulated\nstates in a FeGe wedge and detailed calculations demonstrate that chiral twists\narising near the surfaces of noncentrosymmetric ferromagnets (Meynell et al.\nPhys. Rev. B, 90, 014406 (2014)) provide a stabilization mechanism for skyrmion\nlattices and helicoids in cubic helimagnet nanolayers. The calculated magnetic\nphase diagram for free standing cubic helimagnet nanolayers shows that\nmagnetization processes in these compounds fundamentally differ from those in\nbulk cubic helimagnets and are characterized by the first-order transitions\nbetween modulated phases and the formation of specific multidomain states. The\npaper reports LTEM observations of multidomain patterns in FeGe free-standing\nnanolayers."
    },
    {
        "anchor": "Spatial extent of the excited exciton states in WS$_2$ monolayers from\n  diamagnetic shifts: We experimentally study the radii of excitons in hBN-encapsulated WS2\nmonolayers by means of magneto-optical reflectance spectroscopy at cryogenic\ntemperatures in magnetic fields up to 29 T. We observe field-induced energy\nshifts of the exciton ground and excited states due to valley Zeeman and\ndiamagnetic effects. We find the g factor of the first excited state of\n$-4.2(+/-0.1) to be essentially equal to that of the ground state of\n-4.35(+/-0.1). From diamagnetic shifts we determine the root mean square radii\nof the excitons. The radius of the first excited state is found to be 5-8 nm\nand that of the ground state around 2 nm. Our results further confirm the\nWannier-Mott nature of the exciton quasiparticles in monolayer semiconductors\nand the assignment of the optical resonances in absorption-type measurements.\nThey also provide additional support for the applicability of the effective\nmass hydrogenlike models in these systems.",
        "positive": "Theory and Experimental Investigation of the Quantum Valley Hall Effect: The quantum valley Hall effect (QVHE) has been observed in a variety of\nexperimental setups, both quantum and classical. While extremely promising for\napplications, one should be reminded that QVHE is not an exact topological\nphenomenon and that, so far, it has been fully understood only qualitatively in\ncertain extreme limits. Here we present a technique to relate QVHE systems with\nexact quantum spin-Hall insulators that accept real-space representations,\nwithout taking any extreme limit. Since the bulk-boundary correspondence is\nwell understood for the latter, we are able to formulate precise quantitative\nstatements about the QVHE regime and its robustness against disorder. We\nfurther investigate the effect using a novel experimental platform based on\nmagnetically coupled spinners. Visual renderings, quantitative data and various\ntests of the domain-wall modes are supplied, hence giving an unprecedented\ninsight into the effect."
    },
    {
        "anchor": "Stabilizing topological superconductivity in disordered spin-orbit\n  coupled semiconductor-superconductor heterostructures: We investigate theoretically a one-dimensional semiconductor-superconductor\n(SM-SC) heterostructure with Rashba spin-orbit coupling and parallel Zeeman\nfield in the presence of disorder generated by random charged impurities and\nidentify the optimal regimes for realizing topological superconductivity and\nMajorana zero modes. Using a Green's function approach, we show that upon\nincreasing the disorder strength the stable topological superconducting phase\ncharacterized by robust end-to-end Majorana correlations \"migrates\" toward\nlarger values of the Zeeman field and can be stabilized by increasing the\neffective SM-SC coupling. Based on these findings, we propose a strategy for\naccessing a regime characterized by well-separated Majorana zero modes that is\nbased on (a) enhancing the strength of the effective SM-SC coupling (e.g.,\nthrough interface engineering) and (b) expanding the range of accessible Zeeman\nfields (e.g., by enhancing the gyromagnetic ratio or optimizing the parent\nsuperconductor, to enable the application of larger magnetic fields). While\nthis strategy may still require some reduction of the disorder strength, this\nrequirement is significantly less strict than the corresponding requirement in\na strategy that focuses exclusively on disorder reduction.",
        "positive": "Screening and plasmons in pure and disordered single- and bilayer black\n  phosphorus: We study collective plasmon excitations and screening of disordered single-\nand bilayer black phosphorus beyond the low energy continuum approximation. The\ndynamical polarizability of phosphorene is computed using a tight-binding model\nthat properly accounts for the band structure in a wide energy range.\nElectron-electron interaction is considered within the Random Phase\nApproximation. Damping of the plasmon modes due to different kinds of disorder,\nsuch as resonant scatterers and long-range disorder potentials, is analyzed. We\nfurther show that an electric field applied perpendicular to bilayer\nphosphorene can be used to tune the dispersion of the plasmon modes. For\nsufficiently large electric field, the bilayer BP enters in a topological phase\nwith a characteristic plasmon spectrum, which is gaped in the armchair\ndirection."
    },
    {
        "anchor": "Evidence for Extraction of Photoexcited Hot Carriers from Graphene: We report evidence of nonequilibrium hot carriers extraction from graphene by\ngate-dependent photocurrent study. Scanning photocurrent excited by femtosecond\npulse laser shows unusual gate dependence compared with continuous wave (CW)\nlaser excitation. Power dependence studies further confirm that the\nphotocarriers extracted at the metal/graphene contact are nonequilibrium hot\ncarriers. Hot carrier extraction is found to be most efficient near the Dirac\npoint where carrier lifetime reaches maximum. These observations not only\nprovide evidence of hot carrier extraction from graphene, but also open the\ndoor for graphene based hot carrier optoelectronics.",
        "positive": "Fate of fractional quantum Hall states in open quantum systems:\n  characterization of correlated topological states for the full Liouvillian: Despite previous extensive analysis of open quantum systems described by the\nLindblad equation, it is unclear whether correlated topological states, such as\nfractional quantum Hall states, are maintained even in the presence of the jump\nterm. In this paper, we introduce the pseudo-spin Chern number of the\nLiouvillian which is computed by twisting the boundary conditions only for one\nof the subspaces of the doubled Hilbert space. The existence of such a\ntopological invariant elucidates that the topological properties remain\nunchanged even in the presence of the jump term which does not close the gap of\nthe effective non-Hermitian Hamiltonian (obtained by neglecting the jump term).\nIn other words, the topological properties are encoded into an effective\nnon-Hermitian Hamiltonian rather than the full Liouvillian. This is\nparticularly useful when the jump term can be written as a strictly block-upper\n(-lower) triangular matrix in the doubled Hilbert space, in which case the\npresence or absence of the jump term does not affect the spectrum of the\nLiouvillian. With the pseudo-spin Chern number, we address the characterization\nof fractional quantum Hall states with two-body loss but without gain,\nelucidating that the topology of the non-Hermitian fractional quantum Hall\nstates is preserved even in the presence of the jump term. This numerical\nresult also supports the use of the non-Hermitian Hamiltonian which\nsignificantly reduces the numerical cost. Similar topological invariants can be\nextended to treat correlated topological states for other spatial dimensions\nand symmetry (e.g., one-dimensional open quantum systems with inversion\nsymmetry), indicating the high versatility of our approach."
    },
    {
        "anchor": "Ultra-coherent single photon source: We present a novel type of single photon source in solid state, based on the\ncoherent laser light scattering by a single InAs quantum dot. We demonstrate\nthat the coherence of the emitted single photons is tailored by the resonant\nexcitation with a spectral linewidth below the radiative limit. Our\nultra-coherent source opens the way for integrated quantum devices dedicated to\nthe generation of single photons with high degrees of indistinguishability.",
        "positive": "Noise Thermal Impedance of a Diffusive Wire: The current noise density S of a conductor in equilibrium, the Johnson noise,\nis determined by its temperature T: S=4kTG with G the conductance. The sample's\nnoise temperature Tn=S/(4kG) generalizes T for a system out of equilibrium. We\nintroduce the \"noise thermal impedance\" of a sample as the amplitude of the\noscillation of Tn when heated by an oscillating power. For a macroscopic\nsample, it is the usual thermal impedance. We show for a diffusive wire how\nthis (complex) frequency-dependent quantity gives access to the electron-phonon\ninteraction time in a long wire and to the diffusion time in a shorter one, and\nhow its real part may also give access to the electron-electron inelastic time.\nThese times are not simply accessible from the frequency dependence of S\nitself."
    },
    {
        "anchor": "Characterizing the rate and coherence of single-electron tunneling\n  between two dangling bonds on the surface of silicon: We devise a scheme to characterize tunneling of an excess electron shared by\na pair of tunnel-coupled dangling bonds on a silicon surface -- effectively a\ntwo-level system. Theoretical estimates show that the tunneling should be\nhighly coherent but too fast to be measured by any conventional techniques. Our\napproach is instead to measure the time-averaged charge distribution of our\ndangling-bond pair by a capacitively coupled atomic-force-microscope tip in the\npresence of both a surface-parallel electrostatic potential bias between the\ntwo dangling bonds and a tunable midinfrared laser capable of inducing Rabi\noscillations in the system. With a nonresonant laser, the time-averaged charge\ndistribution in the dangling-bond pair is asymmetric as imposed by the bias.\nHowever, as the laser becomes resonant with the coherent electron tunneling in\nthe biased pair the theory predicts that the time-averaged charge distribution\nbecomes symmetric. This resonant symmetry effect should not only reveal the\ntunneling rate, but also the nature and rate of decoherence of single-electron\ndynamics in our system.",
        "positive": "Field-Free Spin-Orbit Torque driven Switching of Perpendicular Magnetic\n  Tunnel Junction through Bending Current: Current-induced spin-orbit torques (SOTs) enable fast and efficient\nmanipulation of the magnetic state of magnetic tunnel junctions (MTJs), making\nit attractive for memory, in-memory computing, and logic applications. However,\nthe requirement of the external magnetic field to achieve deterministic\nswitching in perpendicular magnetized SOT-MTJs limits its implementation for\npractical applications. Here, we introduce a field-free switching (FFS)\nsolution for the SOT-MTJ device by shaping the SOT channel to create a \"bend\"\nin the SOT current. The resulting bend in the charge current creates a\nspatially non-uniform spin current, which translates into inhomogeneous SOT on\nan adjacent magnetic free layer enabling deterministic switching. We\ndemonstrate FFS experimentally on scaled SOT-MTJs at nanosecond time scales.\nThis proposed scheme is scalable, material-agnostic, and readily compatible\nwith wafer-scale manufacturing, thus creating a pathway for developing purely\ncurrent-driven SOT systems."
    },
    {
        "anchor": "Ultra-robust topologically protected edge states in quasi-1D systems: Topological materials yield robust edge states with potential applications in\nelectronics or quantum technologies. Yet, their simplest Su--Schrieffer--Heeger\nmodel covers only coupling disorders, leaving other types unexplored. Here, by\nstudying a quasi-one-dimensional zigzag model with negative couplings, we show\nnon-chiral edge states simultaneously resilient to dissipation, hopping and\non-site energy disorders. To this end, we derive regularized values of the\ntopological invariant via a novel approach. Our work hints on constructing\ntopological phases even in the absence of usual symmetries.",
        "positive": "Intrinsic supercurrent diode effect in NbSe2 nanobridge: The significance of the superconducting diode effect lies in its potential\napplication as a fundamental component in the development of next-generation\nsuperconducting circuit technology. The stringent operating conditions at low\ntemperatures have posed challenges for the conventional semiconductor diode,\nprimarily due to its exceptionally high resistivity. In response to this\nlimitation, various approaches have emerged to achieve the superconducting\ndiode effect, primarily involving the disruption of inversion symmetry in a\ntwo-dimensional superconductor through heterostructure fabrication. In this\nstudy, we present a direct observation of the supercurrent diode effect in a\nNbSe2 nanobridge with a length of approximately 15 nm, created using focused\nhelium ion beam fabrication. Nonreciprocal supercurrents were identified,\nreaching a peak value of approximately 380 $\\mu$A for each bias polarity at\n$B_{z}^{max} =\\pm 0.2$ mT. Notably, the nonreciprocal supercurrent can be\ntoggled by altering the bias polarity. This discovery of the superconducting\ndiode effect introduces a novel avenue and mechanism through nanofabrication on\na superconducting flake, offering fresh perspectives for the development of\nsuperconducting devices and potential circuits."
    },
    {
        "anchor": "Coherent spin radiation by magnetic nanomolecules and nanoclusters: The peculiarities of coherent spin radiation by magnetic nanomolecules is\ninvestigated by means of numerical simulation. The consideration is based on a\nmicroscopic Hamiltonian taking into account realistic dipole interactions.\nSuperradiance can be realized only when the molecular sample is coupled to a\nresonant electric circuit. The feedback mechanism allows for the achievement of\na fast spin reversal time and large radiation intensity. The influence on the\nlevel of radiation, caused by sample shape and orientation, is analysed. The\nmost powerful coherent radiation is found to occur for an elongated sample\ndirected along the resonator magnetic field.",
        "positive": "Observation of neutral modes in the fractional quantum Hall regime: In the quantum Hall effect regime, taking place in a two-dimensional-electron\ngas under strong magnetic field, currents flow along the edges of the sample.\nFor some particle-hole conjugate states of the fractional regime, e.g., with\nfilling between 1/2 and 1 of the lowest Landau level; early predictions\nsuggested the presence of counter-propagating edge currents in addition to the\nexpected ones. When this did not agree with the measured conductance, it was\nsuggested that disorder and interactions will lead to counterpropagating modes\nthat carry only energy - the so called neutral modes. In addition, a neutral\nupstream mode (Majorana mode) was also expected for selected wavefunctions\nproposed for the even denominator filling 5/2. Here we report on the direct\nobservation of counter-propagating neutral modes in fillings 2/3, 3/5 and 5/2.\nThis was done by injecting such modes and allowing them to impinge on a narrow\nconstriction, which partly reflected them, with two main observed effects: (a)\nA resultant shot noise proportional to the applied voltage on the injecting\ncontact; (b) With simultaneously injecting also a charge mode, the presence of\nthe neutral mode was found to significantly affect the Fano factor and the\ntemperature of the backscattered charge mode. In particular, such observation\nfor filling 5/2, may single out the non-abelian wavefunctions for the state."
    },
    {
        "anchor": "Theory of intrinsic acoustic plasmons in twisted bilayer graphene: We present a theoretical study of the intrinsic plasmonic properties of\ntwisted bilayer graphene (TBG) as a function of the twist angle $\\theta$ (and\nother microscopic parameters such as temperature and filling factor). Our\ncalculations, which rely on the random phase approximation, take into account\nfour crucially important effects, which are treated on equal footing: i) the\nlayer-pseudospin degree of freedom, ii) spatial non-locality of the\ndensity-density response function, iii) crystalline local field effects, and\niv) Hartree self-consistency. We show that the plasmonic spectrum of TBG\ndisplays a smooth transition from a strongly-coupled regime (at twist angles\n$\\theta \\lesssim 2^{\\circ}$), where the low-energy spectrum is dominated by a\nweakly dispersive intra-band plasmon, to a weakly-coupled regime (for twist\nangles $\\theta \\gtrsim 2^{\\circ}$) where an acoustic plasmon clearly emerges.\nThis crossover offers the possibility of realizing tunable mid-infrared\nsub-wavelength cavities, whose vacuum fluctuations may be used to manipulate\nthe ground state of strongly correlated electron systems.",
        "positive": "Low-frequency phase diagram of irradiated graphene and periodically\n  driven spin-1/2 $XY$ chain: We study the Floquet phase diagram of two-dimensional Dirac materials such as\ngraphene and the one-dimensional (1D) spin-1/2 $XY$ model in a transverse field\nin the presence of periodic time-varying terms in their Hamiltonians in the low\ndrive frequency ($\\omega$) regime where standard $1/\\omega$ perturbative\nexpansions fail. For graphene, such periodic time dependent terms are generated\nvia the application of external radiation of amplitude $A_0$ and time period $T\n= 2\\pi/\\omega$, while for the 1D $XY$ model, they result from a two-rate drive\nprotocol with time-dependent magnetic field and nearest-neighbor couplings\nbetween the spins. Using the adiabatic-impulse method, we provide several\nsemi-analytic criteria for the occurrence of changes in the topology of the\nphase bands of such systems. For irradiated graphene, we point out the role of\nthe symmetries of $H(t)$ and $U$ behind such topology changes. Our analysis\nreveals that at low frequencies, phase band topology changes may also happen at\n$t= T/3, 2T/3$ (apart from $t=T$). We chart out the phase diagrams at $t=T/3,\n2T/3,\\, {\\rm and }\\, T$ as a function of $A_0$ and $T$ using exact numerics,\nand compare them with the prediction of the adiabatic-impulse method. We show\nthat several characteristics of these phase diagrams can be analytically\nunderstood from results obtained using the adiabatic-impulse method and point\nout the crucial contribution of the high-symmetry points in the graphene\nBrillouin zone to these diagrams. Finally we study the 1D $XY$ model with a\ntwo-rate driving protocol using the adiabatic-impulse method and exact numerics\nrevealing a phase band crossing at $t=T/2$ and $k=\\pi/2$. We also study the\nanomalous end modes generated by such a drive. We suggest experiments to test\nour theory."
    },
    {
        "anchor": "Tunable point nodes from line node semimetals via application of light: We propose that illumination with light provides a useful platform for\ncreating tunable semimetals. We show that by shining light on semimetals with a\nline degeneracy, one can convert them to a point node semimetal. These point\nnodes are adjustable and their position can be controlled by simply rotating\nthe incident light beam. We also discuss the implications of this change in\nFermi surface topology, as manifested in transport observables.",
        "positive": "Optimal orientation of striped states in the quantum Hall system against\n  external modulations (in 26th ICPS proceedings): The physical properties of striped Hall state in the presence of an external\nunidirectional periodic potential is investigated. The study of searching the\noptimal orientation of the state is reported for the state at filling factor\n$\\nu=2+1/2$ and for the state at higher Landau levels at $l+1/2$ where\n$l=3,4,5,6,7,8$. It is predicted that two phases of the orientation, parallel\nphase and perpendicular phase, exist and a phase transition from one to another\nphase occurs."
    },
    {
        "anchor": "Charge transfer in molecular conductors -- oxidation or reduction?: We discuss the nature of charge transfer in molecular conductors upon\nconnecting to two metallic contacts and imposing a voltage bias across them.\nThe sign of the charge transfer (oxidation vs. reduction) depends on the\nposition of the metal Fermi energy with respect to the molecular levels. In\naddition, the charge transfer depends on the strength of the coupling\n(chemisorption vs. physisorption) with the contacts. A convenient way to\nestablish the nature and onset of the charge transfer and the corresponding\nfeatures in the I-V is to draw an energy level diagram for each spin species.\nStarting from such a level diagram, we argue that transport in the Tour-Reed\nswitching molecules, which consist of a central phenyl ring with a nitroamine\nredox center, involves the oxidation of a highest occupied molecular orbital\n(HOMO)-based level.",
        "positive": "Nonlocal transistor based on pure crossed Andreev reflection in a\n  EuO-graphene/superconductor hybrid structure: We study the interband transport in a superconducting device composed of\ngraphene with EuO-induced exchange interaction. We show that pure crossed\nAndreev reflection can be generated exclusively without the parasitic local\nAndreev reflection and elastic cotunnelling over a wide range of bias and Fermi\nlevels in an EuO-graphene/superconductor/EuO-graphene device. The pure\nnon-local conductance exhibits rapid on/off switching and oscillatory behavior\nwhen the Fermi levels in the normal and the superconducting leads are varied.\nThe oscillation reflects the quasiparticle propagation in the superconducting\nlead and can be used as a tool to probe the subgap quasiparticle mode in\nsuperconducting graphene, which is inaccessible from the current-voltage\ncharacteristics. Our results suggest that the device can be used as a highly\ntunable transistor that operates purely in the non-local and spin-polarized\ntransport regime."
    },
    {
        "anchor": "Chirality-2 fermion induced anti-Klein tunneling in 2D checkerboard\n  lattice: The quantum tunneling effect in the two-dimensional (2D) checkerboard lattice\nis investigated. By analyzing the pseudospin texture of the states in a 2D\ncheckerboard lattice based on the low-energy effective Hamiltonian, we find\nthat this system has a chiral symmetry with chirality equal to 2. Although\ncompared to regular chiral fermions, its pseudospin orientation does not vary\nuniformly. This suggests that the perfect reflection chiral tunneling, also\nknown as the anti-Klein tunneling, is expected to appear in checkerboard\nlattice as well. In order to verify the conjecture, we calculate the\ntransmission probability and find that normally incident electron states can be\nperfectly reflected by the barrier with hole states inside, and vice versa.\nFurthermore, we also numerically calculate the tunneling conductance of the\ncheckerboard nanotube using the recursive Green's function method. The results\nshow that a perfect on-off ratio can be achieved by confining the energy of the\nincident states within a certain range. It also suggests that, by tuning the\nbarrier, the checkerboard nanotube is able to work as a perfect ``band filter\"\nor ``tunneling field effect transistor\", which transmits electrons selectively\nwith respect to the pseudospin of the incident electrons.",
        "positive": "Electronic states, pseudo-spin, and transport in the zinc-blende quantum\n  wells and wires with vanishing band gap: We consider theoretically the electronic structure of quasi-two and\nquasi-one-dimensional heterostructures comprised of III-V and II-VI\nsemiconductors such as InAs/GaInSb and HgCdTe. We show that not only a\nDirac-like dispersion exists in these materials when the energy gap approaches\nzero, but that the states with opposite momentum are orthogonal (i.e. can be\ndescribed by a pseudo-spin), which suppresses backscattering and thereby\nenhances the electron mobility, by analogy with the case of graphene. However,\nunlike in graphene, a quasi-one-dimensional quantum wire with zero gap can be\nrealized, which should eliminate most of the scattering processes and lead to\nlong coherence lengths required for both conventional and ballistic electronic\ndevices."
    },
    {
        "anchor": "Anomalous Spin-Related Quantum Phase in Mesoscopic Hole Rings: We have obtained numerically exact results for the spin-related geometric\nquantum phases that arise in p-type semiconductor ring structures. The\ninterplay between gate-controllable (Rashba) spin splitting and\nquantum-confinement-induced mixing between hole-spin states causes a much\nhigher sensitivity of magnetoconductance oscillations to external parameters\nthan previously expected. Our results imply a much-enhanced functionality of\nhole-ring spin-interference devices and shed new light on recent experimental\nfindings.",
        "positive": "Non-Fermi-Liquid in a modified single electron transistor: At low temperatures, a system built from a small droplet of electrons and a\nlarger, but still finite, droplet may display non-Fermi-liquid behavior.\nStabilization of a multi-channel Kondo fixed point requires fine control of the\nelectrochemical potential in each droplet. The desired fine control can be\nachieved by adjusting voltages on nearby gate electrodes. We study the\nconditions for obtaining this type of non-Fermi-liquid behavior and discuss the\nexperimentally-observable consequences."
    },
    {
        "anchor": "Spin Wave Based Full Adder: Spin Waves (SWs) propagate through magnetic waveguides and interfere with\neach other without consuming noticeable energy, which opens the road to new\nultra-low energy circuit designs. In this paper we build upon SW features and\npropose a novel energy efficient Full Adder (FA) design consisting of The FA 1\nMajority and 2 XOR gates, which outputs Sum and Carry-out are generated by\nmeans of threshold and phase detection, respectively. We validate our proposal\nby means of MuMax3 micromagnetic simulations and we evaluate and compare its\nperformance with state-of-the-art SW, 22nm CMOS, Magnetic Tunnel Junction\n(MTJ), Spin Hall Effect (SHE), Domain Wall Motion (DWM), and Spin-CMOS\nimplementations. Our evaluation indicates that the proposed SW FA consumes\n22.5% and 43% less energy than the direct SW gate based and 22nm CMOS\ncounterparts, respectively. Moreover it exhibits a more than 3 orders of\nmagnitude smaller energy consumption when compared with state-of-the-art MTJ,\nSHE, DWM, and Spin-CMOS based FAs, and outperforms its contenders in terms of\narea by requiring at least 22% less chip real-estate.",
        "positive": "Evolution of Dopant-Concentration-Induced Magnetic Exchange Interaction\n  in Topological Insulator Thin Films: Two essential ingredients for the quantum anomalous Hall (QAH) effect, i.e.\ntopological and magnetic orders, can be combined by doping magnetic ions into a\ntopological insulator (TI) film. Through this approach, the QAH effect has been\nrealized in chromium (Cr)- and/or vanadium (V)-doped TI (Bi,Sb)2Te3 thin films.\nIn this work, we synthesize both V- and Cr-doped Bi2Te3 thin films with\ncontrolled dopant concentration using molecular beam epitaxy (MBE). By\nperforming magneto-transport measurements, we find that both systems show an\nunusual but yet similar ferromagnetic response with respect to magnetic dopant\nconcentration, specifically the Curie temperature does not increase\nmonotonically but shows a local maximum at a critical dopant concentration. Our\nangle-resolved photoemission spectroscopy (ARPES) measurements show that the\nCr/V doping introduces hole carriers into Bi2Te3, which consequently move the\nchemical potential toward the charge neutral point. In addition, the Cr/V\ndoping also reduces the spin-orbit coupling of Bi2Te3 which drives it from a\nnontrivial TI to a trivial semiconductor. The unusual ferromagnetic response\nobserved in Cr/V-doped Bi2Te3 thin films is attributed to the\ndopant-concentration-induced magnetic exchange interaction, which displays the\nevolution from the van Vleck-type ferromagnetism in a nontrivial magnetic TI to\nthe Ruderman-Kittel-Kasuya-Yosida (RKKY)-type ferromagnetism in a trivial\ndiluted magnetic semiconductor. Our work provides insights into the\nferromagnetic properties of magnetically doped TI thin films and facilitates\nthe pursuit of high-temperature QAH effect."
    },
    {
        "anchor": "Magnetic Bloch Theorem and Reentrant Flat Bands in Twisted Bilayer\n  Graphene at $2\u03c0$ Flux: Bloch's theorem is the centerpiece of topological band theory, which itself\nhas defined an era of quantum materials research. However, Bloch's theorem is\nbroken by a perpendicular magnetic field, making it difficult to study\ntopological systems in strong flux. For the first time, moir\\'e materials have\nmade this problem experimentally relevant, and its solution is the focus of\nthis work. We construct gauge-invariant irreps of the magnetic translation\ngroup at $2\\pi$ flux on infinite boundary conditions, allowing us to give\nanalytical expressions in terms of the Siegel theta function for the magnetic\nBloch Hamiltonian, non-Abelian Wilson loop, and many-body form factors. We\nillustrate our formalism using a simple square lattice model and the\nBistritzer-MacDonald Hamiltonian of twisted bilayer graphene, obtaining\nreentrant ground states at $2\\pi$ flux under the Coulomb interaction.",
        "positive": "Theory of charged impurity scattering in two dimensional graphene: We review the physics of charged impurities in the vicinity of graphene. The\nlong-range nature of Coulomb impurities affects both the nature of the ground\nstate density profile as well as graphene's transport properties. We discuss\nthe screening of a single Coulomb impurity and the ensemble averaged density\nprofile of graphene in the presence of many randomly distributed impurities.\nFinally, we discuss graphene's transport properties due to scattering off\ncharged impurities both at low and high carrier density."
    },
    {
        "anchor": "Black Phosphorus Radio-Frequency Transistors: Few-layer and thin film forms of layered black phosphorus (BP) have recently\nemerged as a promising material for applications in high performance\nnanoelectronics and infrared optoelectronics. Layered BP thin film offers a\nmoderate bandgap of around 0.3 eV and high carrier mobility, leading to\ntransistors with decent on-off ratio and high on-state current density. Here,\nwe demonstrate the gigahertz frequency operation of black phosphorus\nfield-effect transistors for the first time. The BP transistors demonstrated\nhere show excellent current saturation with an on-off ratio exceeding 2000. We\nachieved a current density in excess of 270 mA/mm and DC transconductance above\n180 mS/mm for hole conduction. Using standard high frequency characterization\ntechniques, we measured a short-circuit current-gain cut-off frequency fT of 12\nGHz and a maximum oscillation frequency fmax of 20 GHz in 300 nm channel length\ndevices. BP devices may offer advantages over graphene transistors for high\nfrequency electronics in terms of voltage and power gain due to the good\ncurrent saturation properties arising from their finite bandgap, thus enabling\nthe future ubiquitous transistor technology that can operate in the multi-GHz\nfrequency range and beyond.",
        "positive": "Spin-to-charge conversion in lateral and vertical\n  topological-insulator/ferromagnet heterostructures with microwave-driven\n  precessing magnetization: Using the charge-conserving Floquet-Green function approach to open quantum\nsystems driven by external time periodic potential, we analyze how spin current\npumped (in the absence of any dc bias voltage) by the precessing magnetization\nof a ferromagnetic (F) layer is injected {\\em laterally} into the interface\nwith strong spin-orbit coupling (SOC) and converted into charge current flowing\nin the same direction. In the case of metallic interface with the Rashba SOC\nused in experiments [Nature Comm. {\\bf 4}, 2944 (2013)], both spin\n$I^{S_\\alpha}$ and charge $I$ current flow within it where $I/I^{S_\\alpha}\n\\simeq$ 2--8\\% (depending on the precession cone angle), while for\nF/topological-insulator (F/TI) interface employed in related experiments\n(arXiv:1312.7091) the conversion efficiency is greatly enhanced $I/I^{S_\\alpha}\n\\simeq$ 40--60\\% due to perfect spin-momentum locking on the surface of TI. The\nspin-to-charge conversion occurs also when spin current is pumped {\\em\nvertically} through the F/TI interface with smaller efficiency $I/I^{S_\\alpha}\n\\sim 0.001\\%$, but with charge current signal being sensitive to whether the\nDirac fermions at the interface are massive or massless."
    },
    {
        "anchor": "Picosecond Spin-Orbit Torque Induced Coherent Magnetization Switching in\n  a Ferromagnet: Electrically controllable non-volatile magnetic memories show great potential\nfor the replacement of semiconductor-based technologies. Recently there has\nbeen strong interest in spin-orbit torque (SOT) induced magnetization reversal\ndue to the device's increased lifetime and speed of operation. However, recent\nSOT switching studies reveal an incubation delay in the ~ns range due to\nstochasticity in the nucleation of a magnetic domain during reversal. Here, we\nexperimentally demonstrate ultrafast SOT-induced magnetization switching\ndynamics of a ferromagnet with no incubation delay by avoiding the nucleation\nprocess and driving the magnetization coherently. We employ an ultrafast\nphoto-conducting switch and a co-planar strip line to generate and guide ~ps\ncurrent pulses into the heavy metal/ferromagnet layer stack and induce\nultrafast SOT. We use magneto-optical probing to investigate the magnetization\nswitching dynamics with sub-picosecond time resolution. Depending on the\nrelative current pulse and in-plane magnetic field polarities, we observe\neither an ultrafast demagnetization and subsequent recovery along with a\nSOT-induced precessional oscillation, or ultrafast SOT switching. The\nmagnetization zero-crossing occurs in ~70 ps, which is approximately an order\nof magnitude faster than previous studies. Complete switching needs ~250 ps and\nis limited by the heat diffusion to the substrate. We use a macro-magnetic\nsimulation coupled with an ultrafast heating model to analyze the effect of\nultrafast thermal anisotropy torque and current-induced torque in the observed\ndynamics. Good agreement between our experimental results and the macro-spin\nmodel shows that the switching dynamics are coherent and present no noticeable\nincubation delay. Our work suggests a potential pathway toward dramatically\nincreasing the writing speed of SOT magnetic random-access memory devices.",
        "positive": "Hofstadter Topology with Real Space Invariants and Reentrant Projective\n  Symmetries: Adding magnetic flux to a band structure breaks Bloch's theorem by realizing\na projective representation of the translation group. The resulting Hofstadter\nspectrum encodes the non-perturbative response of the bands to flux. Depending\non their topology, adding flux can enforce a bulk gap closing (a Hofstadter\nsemimetal) or boundary state pumping (a Hofstadter topological insulator). In\nthis work, we present a real-space classification of these Hofstadter phases.\nWe give topological indices in terms of symmetry-protected Real Space\nInvariants (RSIs) which encode bulk and boundary responses of fragile\ntopological states to flux. In fact, we find that the flux periodicity in\ntight-binding models causes the symmetries which are broken by the magnetic\nfield to reenter at strong flux where they form projective point group\nrepresentations. We completely classify the reentrant projective point groups\nand find that the Schur multipliers which define them are Arahanov-Bohm phases\ncalculated along the bonds of the crystal. We find that a nontrivial Schur\nmultiplier is enough to predict and protect the Hofstadter response with only\nzero-flux topology."
    },
    {
        "anchor": "Thermally assisted Skyrmion drag in a nonuniform electric field: Magnetic skyrmions are topologically protected excitations of the\nmagnetization vector field with promising applications in spintronics and\nspin-caloritronics, particularly due to their high mobility. Skyrmions can be\nsteered by a spin-polarized charge current or by exposure to a magnonic spin\ncurrent. Here, we propose a further method for driving skyrmions by applying an\ninhomogeneous electric field and a homogeneous thermal bias. We show that the\ninhomogeneous electric torque leads to an efficient skyrmionic drag which can\nbe thermally assisted as to enhance the skyrmion velocity. The calculations and\nanalysis are limited to insulating samples; for conducting materials the\ninfluence of the inhomogeneous electric field on the charge carriers need to be\ntaken also into account.",
        "positive": "Large spin-orbit effects in small quantum dots: We consider small ballistic quantum dots weakly coupled to the leads in the\nchaotic regime and look for significant spin-orbit effects. We find that these\neffects can become quite prominent in the vicinity of degeneracies of many-body\nenergies. We illustrate the idea by considering a case where the intrinsic\nexchange term -JS^2 brings singlet and triplet many-body states near each\nother, while an externally tunable Zeeman term then closes the gap between the\nsinglet and the one of the triplet states (with spin projection parallel the\nexternal field). Near this degeneracy, the spin-orbit coupling leads to a\nstriking temperature dependence of the conductance, with observable effects of\norder unity at temperatures lower than the strength of the spin-orbit coupling.\nUnder favorable circumstances, spelled out in the paper, these order unity\neffects in the conductance persist to temperatures much higher than the\nspin-orbit coupling strength. Our conclusions are unaffected by the presence of\nnon-universal perturbations. We suggest a class of experiments to explore this\nregime."
    },
    {
        "anchor": "Spin Hall conductivity in insulators with non-conserved spin: We study the linear response of a spin current to a small electric field in a\ntwo-dimensional crystalline insulator with non-conserved spin. We adopt the\nspin current operator proposed in [J. Shi et al., Phys. Rev. Lett. 96, 076604\n(2006)], which satisfies a continuity equation and fits the Onsager relations.\nWe use the time-independent perturbation theory to present a formula for the\nspin Hall conductivity, which consists of a \"Chern-like\" term, reminiscent of\nthe Kubo formula obtained for the quantum Hall systems, and a correction term\nthat accounts for the non-conservation of spin. We illustrate our findings on\nthe Bernevig-Hughes-Zhang model and the Kane-Mele model for time-reversal\nsymmetric topological insulators and show that the correction term scales\nquadratically with the amplitude of the spin-conservation-breaking terms. In\nboth models, the spin Hall conductivity deviates from the quantized value when\nspin is not conserved.",
        "positive": "Minimal Non-orthogonal Gate Decomposition for Qubits with Limited\n  Control: In quantum control theory, a question of fundamental and practical interest\nis how an arbitrary unitary transformation can be decomposed into minimum\nnumber of elementary rotations for implementation, subject to various physical\nconstraints. Examples include the singlet-triplet (ST) and exchange-only (EO)\nqubits in quantum-dot systems, and gate construction in the Solovay-Kitaev\nalgorithm. For two important scenarios, we present complete solutions to the\nproblems of optimal decomposition of single-qubit unitary gates with\nnon-orthogonal rotations. For each unitary gate, we give the criteria for\ndetermining the minimal number of pieces, the explicit gate construction\nprocedure, as well as a computer code for practical uses. Our results include\nan analytic explanation to the four-gate decomposition of EO qubits, previously\ndetermined numerically by Divincenzo et al [Nature, 408, 339 (2000)].\nFurthermore, compared with the approaches of Ramon sequence and its variant\n[Phys. Rev. Lett., 118, 216802 (2017)], our method can reduce about 50% of gate\ntime for ST qubits. Finally, our approach can be extended to solve the problem\nof optimal control of topological qubits, where gate construction is achieved\nthrough the braiding operations."
    },
    {
        "anchor": "Nonequilibrium Kondo model: Crossover from weak to strong coupling: We analyze the nonequilibrium Kondo model at finite voltage and temperature\nby using a new formulation of the real-time renormalization group method with\nthe Laplace variable as the flow parameter. We evaluate the energy-dependent\nspin relaxation rate and nonlinear conductance, and derive an approximate form\nfor the universal line shape for the latter in the whole crossover regime from\nweak to strong coupling. The results are shown to agree well with exact methods\nin equilibrium, Fermi-liquid theory, weak-coupling expansions, and recent\nexperiments. For the transient spin dynamics we find a universal exponential\ndecay in the long-time limit along with a truncation-dependent pre-exponential\npower law. For multichannel models a pure power-law decay typical for\nnon-Fermi-liquid behaviour is predicted.",
        "positive": "Raman imaging and electronic properties of graphene: Graphite is a well-studied material with known electronic and optical\nproperties. Graphene, on the other hand, which is just one layer of carbon\natoms arranged in a hexagonal lattice, has been studied theoretically for quite\nsome time but has only recently become accessible for experiments. Here we\ndemonstrate how single- and multi-layer graphene can be unambiguously\nidentified using Raman scattering. Furthermore, we use a scanning Raman set-up\nto image few-layer graphene flakes of various heights. In transport experiments\nwe measure weak localization and conductance fluctuations in a graphene flake\nof about 7 monolayer thickness. We obtain a phase-coherence length of about 2\n$\\mu$m at a temperature of 2 K. Furthermore we investigate the conductivity\nthrough single-layer graphene flakes and the tuning of electron and hole\ndensities via a back gate."
    },
    {
        "anchor": "Fermions in optical lattices near a Feshbach resonance: from band\n  insulator to Mott insulator: We study a model of an equal mixture of two species of fermions in a deep\noptical lattice at a filling of two fermions per site. At weak inter-species\ninteraction, the system is a band insulator. When the inter-species interaction\nis tuned via a Feshbach resonance to be larger than an energy related to the\nenergy separation of the first and second Bloch band, atoms populate equally\nthe two Bloch bands. With weak tunneling between sites of the optical lattice,\nthe system becomes a Mott insulator with the low energy effective Hamiltonian\nof a spin-1 Heisenberg antiferromagnet, because of a Hund's rule like coupling\nbetween the two bands. We discuss experimental signatures of these two types of\ninsulators.",
        "positive": "Quantum Nernst Effect: It is theoretically predicted that the Nernst coefficient is strongly\nsuppressed and the thermal conductance is quantized in the quantum Hall regime\nof the two-dimensional electron gas. The Nernst effect is the induction of a\nthermomagnetic electromotive force in the $y$ direction under a temperature\nbias in the $x$ direction and a magnetic field in the $z$ direction. The\nquantum nature of the Nernst effect is analyzed with the use of a circulating\nedge current and is demonstrated numerically. The present system is a physical\nrealization of the non-equilibrium steady state."
    },
    {
        "anchor": "Yu-Shiba-Rusinov states in 2D superconductors with arbitrary Fermi\n  contours: Magnetic impurities on a superconductor induce sub-gap Yu-Shiba-Rusinov (YSR)\nbound states, localized at the impurity site and fading away from it for\ndistances up to several nanometers. In this article, we present a theoretical\nmethod to calculate the spatial distribution of the YSR spectrum of a\ntwo-dimensional superconductor with arbitrary Fermi contours (FCs) in the\npresence of magnetic impurities. Based on the Green's Function (GF) formalism,\nwe obtain a general analytical expression by approximating an arbitrary contour\nshape to a regular polygon. This method allows us to show the connection\nbetween the spatial decay (and, hence, the extension) of YSR states and the\nshape of the FC of the host superconductor. We further apply this formalism to\ncompute the evolution of YSR states in the presence of a nearby impurity atom,\nand compare the results with Scanning Tunneling Microscopy (STM) measurements\non interacting manganese dimers on the $\\beta$-Bi2Pd superconductor. The method\ncan be easily extended to any arbitrary number of magnetically coupled\nimpurities, thus, providing a useful tool for simulating the spectral\nproperties of interacting YSR states in artificial atomic nanostructures.",
        "positive": "Electronic Kapitza conductance and related kinetic coefficients at an\n  interface between n-type semiconductors: We calculate the Kapitza conductance, which is the proportionality\ncoefficient between heat flux and temperature jump at the interface, for the\ncase of two conducting solids separated by the interface. We show that for\nconducting solids in a non-equilibrium state, there should also arise the\nelectrochemical potential jump at the interface. Hence to describe linear\ntransport at the interface we need three kinetic coefficients: interfacial\nanalogs of electric and heat conductances and interfacial analog of the Seebeck\ncoefficient. We calculate these coefficients for the case of an interface\nbetween n-type semiconductors. We perform calculations in the framework of\nBoltzmann transport theory. We have found out that the interfacial analog of\nthe Seebeck coefficient for some range of parameters of the considered\nsemiconductors, has a high value of about $10^{-3}$ V/K. Thus this effect has\nthe potential to be used for the synthesis of effective thermoelectric\nmaterials."
    },
    {
        "anchor": "Snaking states on a cylindrical surface in a perpendicular magnetic\n  field: We calculate electronic states on a closed cylindrical surface as a model of\na core-shell nanowire. The length of the cylinder can be infinite or finite. We\ndefine cardinal points on the circumference of the cylinder and consider a\nspatially uniform magnetic field perpendicular to the cylinder axis,in the\ndirection South-North. The orbital motion of the electrons depends on the\nradial component of the field which is not uniform around the circumference: it\nis equal to the total field at North and South, but vanishes at the West and\nEast sides. For a strong field, when the magnetic length is comparable to the\nradius of the cylinder, the electronic states at North and South become\nlocalized cyclotron orbits, whereas at East and West the states become long and\nnarrow snaking orbits propagating along the cylinder. The energy of the\ncyclotron states increases with the magnetic field whereas the energy of the\nsnaking states is stable. Consequently, at high magnetic fields the electron\ndensity vanishes at North and South and concentrates at East and West. We\ninclude spin-orbit interaction with linear Rashba and Dresselhaus models. For a\ncylinder of finite length the Dresselhaus interaction produces an axial twist\nof the charge density relative to the center of the wire, which may be\namplified in the presence of the Rashba interaction.",
        "positive": "Slow non-exponential phase relaxation and enhanced mesoscopic kinetic\n  inductance noise in disordered superconductors: Mesoscopic low frequency noise in electrical characteristics of disordered\nconductors is a result of dynamic quantum interference pattern due to motion of\ndefects. This has been firmly established by demonstrating the characteristic\npartial suppression of the noise amplitude by the dephasing effect of a weak\nexternal magnetic field. The spatial correlation of the quantum interference\npattern in disordered normal state conductors is invariably limited by the\nexponential phase relaxation due to inelastic processes. In this paper we\ndevelop a quantitative theory of the mesoscopic noise in the s-wave\nsuperconducting phase of a strongly disordered superconductor (such that the\nsuperconducting coherence length is much longer than the mean free path). We\nfind that the superconducting coherence length limits the quantum interference\neffects in superconductors. However, in contrast to the normal phase, the decay\nof the phase relaxation on the scale of the superconducting coherence length is\nnon-exponential. This unusual slow relaxation manifests in the enhanced\namplitude of the mesoscopic noise in superconductors and a peculiar non-linear\nscaling of the amplitude with the strength/number of mobile defects in very\nthin superconducting films and wires (effectively 2D and 1D with respect to the\nsuperconducting coherence length). Mesoscopic noise sets a natural limit on the\nquality of kinetic inductance elements."
    },
    {
        "anchor": "Direct Interband Light Absorption in Strongly Prolated Ellipsoidal\n  Quantum Dots' Ensemble: Within the framework of adiabatic approximation, the energy levels and direct\ninterband light absorption in a strongly prolated ellipsoidal quantum dot are\nstudied. Analytical expressions for the particle energy spectrum and absorption\nthreshold frequencies in three regimes of quantization are obtained. Selection\nrules for quantum transitions are revealed. Absorption edge and absorption\ncoefficient for three regimes of size quantization (SQ) are also considered. To\nfacilitate the comparison of obtained results with the probable experimental\ndata, size dispersion distribution of growing quantum dots by the small semiaxe\nin the regimes of strong and weak SQ by two experimentally realizing\ndistribution functions have been taken into account. Distribution functions of\nLifshits-Slezov and Gaussian have been considered.",
        "positive": "Non-equilibrium Spin-Hall Effect in Aluminum and Tungsten: The method proposed by us in [1], which eliminates obstacles in the\napplication of electrical methods for studying the spin-Hall effect (SHE) by\ncreating a spin unbalance, which generates a charge unbalance, using the form\neffect without using polarized injected current, is used in this work to study\nand compare SHE of different origin - internal (band) and external (structural\nand impurity). The internal SHE (ISHE) was studied on ultrapure single crystal\nsamples of uncompensated (aluminum) and compensated (tungsten) metals. The\ninfluence of external factors on SHE was studied on polycrystalline and\nimpurity aluminum samples. The investigations were carried out in the region of\nsmall magnetic fields, which ensure the symmetry of the conventional Hall\neffect (CHE), which makes it possible to study the chiral behavior of the spin\nHall effect."
    },
    {
        "anchor": "Quantum heat transfer in harmonic chains with self consistent\n  reservoirs: Exact numerical simulations: We describe a numerical scheme for exactly simulating the heat current\nbehavior in a quantum harmonic chain with self-consistent reservoirs.\nNumerically-exact results are compared to classical simulations and to the\nquantum behavior under the linear response approximation. In the classical\nlimit or for small temperature biases our results coincide with previous\ncalculations. At large bias and for low temperatures the quantum dynamics of\nthe system fundamentally differs from the close-to-equilibrium behavior,\nrevealing in particular the effect of thermal rectification for asymmetric\nchains. Since this effect is absent in the classical analog of our model, we\nconclude that in the quantum model studied here thermal rectification is a\npurely quantum phenomenon, rooted in the quantum statistics.",
        "positive": "Scattering Theory of Current-Induced Spin Polarization: We construct a novel scattering theory to investigate magnetoelectrically\ninduced spin polarizations. Local spin polarizations generated by electric\ncurrents passing through a spin-orbit coupled mesoscopic system are measured by\nan external probe. The electrochemical and spin-dependent chemical potentials\non the probe are controllable and tuned to values ensuring that neither charge\nnor spin current flow between the system and the probe, on time-average. For\nthe relevant case of a single-channel probe, we find that the resulting\npotentials are exactly independent of the transparency of the contact between\nthe probe and the system. Assuming that spin relaxation processes are absent in\nthe probe, we therefore identify the local spin-dependent potentials in the\nsample at the probe position, and hence the local current-induced spin\npolarization, with the spin-dependent potentials in the probe itself. The\nstatistics of these local chemical potentials is calculated within random\nmatrix theory. While they vanish on spatial and mesoscopic average, they\nexhibit large fluctuations, and we show that single systems typically have spin\npolarizations exceeding all known current-induced spin polarizations by a\nparametrically large factor. Our theory allows to calculate quantum\ncorrelations between spin polarizations inside the sample and spin currents\nflowing out of it. We show that these large polarizations correlate only weakly\nwith spin currents in external leads, and that only a fraction of them can be\nconverted into a spin current in the linear regime of transport, which is\nconsistent with the mesoscopic universality of spin conductance fluctuations.\nWe numerically confirm the theory."
    },
    {
        "anchor": "Magneto-transport in the monolayer MoS2 material system for\n  high-performance field-effect transistor applications: Electronic transport in monolayer MoS2 is significantly constrained by\nseveral extrinsic factors despite showing good prospects as a transistor\nchannel material. Our paper aims to unveil the underlying mechanisms of the\nelectrical and magneto-transport in monolayer MoS2. In order to quantitatively\ninterpret the magneto-transport behavior of monolayer MoS2 on different\nsubstrate materials, identify the underlying bottlenecks, and provide\nguidelines for subsequent improvements, we present a deep analysis of the\nmagneto-transport properties in the diffusive limit. Our calculations are\nperformed on suspended monolayer MoS2 and MoS2 on different substrate materials\ntaking into account remote impurity and the intrinsic and extrinsic phonon\nscattering mechanisms. We calculate the crucial transport parameters such as\nthe Hall mobility, the conductivity tensor elements, the Hall factor, and the\nmagnetoresistance over a wide range of temperatures, carrier concentrations,\nand magnetic fields. The Hall factor being a key quantity for calculating the\ncarrier concentration and drift mobility, we show that for suspended monolayer\nMoS2 at room temperature, the Hall factor value is around 1.43 for magnetic\nfields ranging from 0.001 to 1 Tesla, which deviates significantly from the\nusual value of unity. In contrast, the Hall factor for various substrates\napproaches the ideal value of unity and remains stable in response to the\nmagnetic field and temperature. We also show that the MoS2 over an Al2O3\nsubstrate is a good choice for the Hall effect detector. Moreover, the\nmagnetoresistance increases with an increase in magnetic field strength for\nsmaller magnetic fields before reaching saturation at higher magnetic fields.\nThe presented theoretical model quantitatively captures the scaling of mobility\nand various magnetoresistance coefficients with temperature, carrier densities\nand magnetic fields.",
        "positive": "New quantum phases of matter: Topological Materials: In this article, we provide an overview of the basic concepts of novel\ntopological materials. This new class of materials developed by combining the\nWeyl/Dirac fermionic electron states and magnetism, provide a materials-science\nplatform to test predictions of the laws of topological physics. Owing to their\ndissipationless transport, these materials hold high promises for technological\napplications in quantum computing and spintronics devices."
    },
    {
        "anchor": "Cooperative amplification of energy transfer in plasmonic systems: We study cooperative effects in energy transfer (ET) from an ensemble of\ndonors to an acceptor near a plasmonic nanostructure. We demonstrate that in\ncooperative regime ET takes place from plasmonic superradiant and subradiant\nstates rather than from individual donors leading to a significant increase of\nET efficiency. The cooperative amplification of ET relies on the large coupling\nof superradiant states to external fields and on the slow decay rate of\nsubradiant states. We show that superradiant and subradiant ET mechanisms are\nefficient in different energy domains and therefore can be utilized\nindependently. We present numerical results demonstrating the amplification\neffect for a layer of donors and an acceptor on a spherical plasmonic\nnanoparticle.",
        "positive": "Unbounded fluctuations in transport through an integrable cavity: We derive a semiclassical scheme for the conductance through a rectangular\ncavity. The transmission amplitudes are expressed as a sum over families of\ntrajectories rather than a sum over isolated trajectories. The contributing\nfamilies are obtained from the evaluation of a finite number of continued\nfractions. We find that, contrary to the chaotic case, the conductance\nfluctuations increase with the incoming energy and the correlation function\nexhibits a singularity at the origin."
    },
    {
        "anchor": "Unlocking the electronic, optical and transport properties of\n  semiconductor coupled quantum dots using first principles methods: Semiconductor coupled quantum dots provide a unique opportunity of tuning\nbandgaps by tailoring band offsets, making them ideal for photovoltaic and\nother applications. Here, we have studied stability, trends in the band gap,\nband offsets, and optical properties for a series of coupled quantum dots\ncomprised of II-VI semiconductor using a hybrid functional method. We have\nshown how the quantum confinement and interfacial strain considerably affect\nthe band gap and band offsets for these heterostructures at the nanoscale. We\nshow that the trend in band offsets obtained from our first-principles\nelectronic structure calculations agrees with that obtained from the method of\naverage electrostatic potential. It is found that a common anion rule for band\noffset is followed for these heterostructures at the nanoscale. Further, the\ncalculated optical absorption spectra for these coupled quantum dots reveal\nthat absorption peaks lie in the ultra-violet (UV) region, whereas absorption\nedges are in the visible region. In addition to electronic and optical\nproperties, we have also explored transport properties for two representative\ncoupled quantum dots, either having common cations or common anions, which\nrevealed asymmetric nature in current-voltage characteristics. Therefore these\nsemiconductor coupled quantum dots may be useful for photovoltaic,\nlight-emitting diode, and opto-electronic devices.",
        "positive": "Dislocations in stacking and commensurate-incommensurate phase\n  transition in bilayer graphene and hexagonal boron nitride: Dislocations corresponding to a change of stacking in two-dimensional\nhexagonal bilayers, graphene and boron nitride, and associated with boundaries\nbetween commensurate domains are investigated using the two-chain\nFrenkel-Kontorova model on top of ab initio calculations. Structural\ntransformations of bilayers in which the bottom layer is stretched and the\nupper one is left to relax freely are considered for gradually increased\nelongation of the bottom layer. Formation energies of dislocations, dislocation\nwidth and orientation of the boundary between commensurate domains are analyzed\ndepending on the magnitude and direction of elongation. The second-order phase\ntransition from the commensurate phase to the incommensurate one with multiple\ndislocations is predicted to take place at some critical elongation. The order\nparameter for this transition corresponds to the density of dislocations, which\ngrows continuously upon increasing the elongation of the bottom layer above the\ncritical value. In graphene and metastable boron nitride with the layers\naligned in the same direction, where elementary dislocations are partial, this\ntransition, however, is preceded by formation of the first dislocation at the\nelongation smaller than the critical one. The phase diagrams including this\nintermediate state are plotted in coordinates of the magnitude and direction of\nelongation of the bottom layer."
    },
    {
        "anchor": "Microtubules as electron-based topological insulators: The microtubule is a cylindrical biological polymer that plays key roles in\ncellular structure, transport, and signalling. In this work, based on studies\nof electronic properties of polyacetelene and mechanical properties of\nmicrotubules themselves (see Phys. Rev. Lett. 103, 248101), we explore the\npossibility that microtubules could act as topological insulators that are\ngapped to electronic excitations in the bulk but possess robust electronic\nbounds states at the tube ends. Through analyses of structural and electronic\nproperties, we model the microtubule as a cylindrical stack of\nSu-Schrieffer-Heeger chains (originally proposed in the context of\npolyacetylene) describing electron hopping between the underlying dimerized\ntubulin lattice sites. We postulate that the microtubule is mostly uniform,\ndominated purely by GDP-bound dimers, and is capped by a disordered regime due\nto the presence of GTP-bound dimers as well. In the uniform region, we identify\nthe electron hopping parameter regime in which the microtubule is a topological\ninsulator. We then show the manner in which these topological features remain\nrobust when the hopping parameters are disordered. We briefly mention possible\nbiological implications for these microtubules to possess topologically robust\nelectronic bound states.",
        "positive": "Magnetism in a lattice of spinor Bose condensates: We study the ground state magnetic properties of ferromagnetic spinor\nBose-Einstein condensates confined in a deep optical lattices. In the Mott\ninsulator regime, the ``mini-condensates'' at each lattice site behave as\nmesoscopic spin magnets that can interact with neighboring sites through both\nthe static magnetic dipolar interaction and the light-induced dipolar\ninteraction. We show that such an array of spin magnets can undergo a\nferromagnetic or anti-ferromagnetic phase transition under the magnetic dipolar\ninteraction depending on the dimension of the confining optical lattice. The\nground-state spin configurations and related magnetic properties are\ninvestigated in detail."
    },
    {
        "anchor": "Direct visualization of hybrid excitons in van der Waals\n  heterostructures: Van der Waals heterostructures show fascinating physics including trapped\nmoire exciton states, anomalous moire exciton transport, generalized Wigner\ncrystals, etc. Bilayers of transition metal dichalcogenides (TMDs) are\ncharacterized by long-lived spatially separated interlayer excitons. Provided a\nstrong interlayer tunneling, hybrid exciton states consisting of interlayer and\nintralayer excitons can be formed. Here, electrons and/or holes are in a\nsuperposition of both layers. Although crucial for optics, dynamics, and\ntransport, hybrid excitons are usually optically inactive and have therefore\nnot been directly observed yet. Based on a microscopic and material-specific\ntheory, we show that time- and angle-resolved photoemission spectroscopy\n(tr-ARPES) is the ideal technique to directly visualize these hybrid excitons.\nConcretely, we predict a characteristic double-peak ARPES signal arising from\nthe hybridized hole in the MoS$_2$ homobilayer. The relative intensity is\nproportional to the quantum mixture of the two hybrid valence bands at the\n$\\Gamma$ point. Due to the strong hybridization, the peak separation of more\nthan 0.5 eV can be resolved in ARPES experiments. Our study provides a concrete\nrecipe of how to directly visualize hybrid excitons and how to distinguish them\nfrom the usually observed regular excitonic signatures.",
        "positive": "Oligothiophene nano-rings as electron resonators for whispering gallery\n  modes: Structural and electronic properties of oligothiophene nano-wires and rings\nsynthesized on a Au(111) surface are investigated by scanning tunneling\nmicroscopy. The spectroscopic data of the linear and cyclic oligomers show\nremarkable differences which, to a first approximation, can be accounted by\nconsidering electronic states confinement to one-dimensional (1D) boxes having\nrespectively fixed and periodic boundary conditions. A more detailed analysis\nshows that polythiophene must be treated as a ribbon (i.e. having an effective\nwidth) rather than a purely 1D structure. A fascinating consequence is that the\nmolecular nano-rings act as whispering gallery mode resonators for electrons,\nopening the way for new applications in quantum-electronics."
    },
    {
        "anchor": "Molecule-Induced Conformational Change in Boron Nitride Nanosheets with\n  Enhanced Surface Adsorption: Surface interaction is extremely important to both fundamental research and\npractical application. Physisorption can induce shape and structural distortion\n(i.e. conformational changes) in macromolecular and biomolecular adsorbates,\nbut such phenomenon has rarely been observed on adsorbents. Here, we\ndemonstrate theoretically and experimentally that atomically thin boron nitride\n(BN) nanosheets as an adsorbent experience conformational changes upon surface\nadsorption of molecules, increasing adsorption energy and efficiency. The study\nnot only provides new perspectives on the strong adsorption capability of BN\nnanosheets and many other two-dimensional nanomaterials but also opens up\npossibilities for many novel applications. For example, we demonstrate that BN\nnanosheets with the same surface area as bulk hBN particles are more effective\nin purification and sensing.",
        "positive": "Temperature dependent PL from SWNTs: Photoluminescence (PL) and photoluminescence excitation (PLE) spectroscopy of\npillar-suspended single-walled carbon nanotubes has been measured for\ntemperatures between 300 K and 5 K."
    },
    {
        "anchor": "Bottom-up fabrication of highly ordered metal nanostructures by\n  hierarchical self-assembly: In a hierarchical nanopatterning routine relying exclusively on self-assembly\nprocesses we combine crystal surface reconstruction, microphase separation of\ncopolymers, and selective metal diffusion to produce monodisperse metal\nnanostructures in highly regular arrays covering areas of square centimeters.\nIn-situ GISAXS during Fe nanostructure formation evidences the outstanding\nstructural order in the self-assembling system and hints at possibilities of\nsculpting nanostructures by external process parameters. Thus, we demonstrate\nthat nanopatterning via self-assembly is a competitive alternative to\nlithography-based routines, achieving comparable pattern regularity, feature\nsize, and patterned areas with considerably reduced effort. The option for\nin-situ investigations during pattern formation, the possibility of customizing\nthe nanostructure morphology, the capacity to pattern arbitrarily large areas\nwith ultra-high structure densities, and the potential of addressing the\nnanostructures individually enable numerous applications, e.g., in high-density\nmagnetic data storage, in functional nanostructured materials, e.g., for\nphotonics or catalysis, or in sensing based on surface plasmon resonances.",
        "positive": "Long range phase coherencein double barrier magnetic tunnel junctions\n  with large thick metallic quantum well: Double barrier heterostructures are model systems for the study of electron\ntunneling and discrete energy levels in a quantum well (QW). Until now resonant\ntunneling phenomena in metallicQW have been observed for limited thicknesses\n(1-2 nm) under which electron phase coherence is conserved. In the present\nstudy we show evidence of QW resonance states in Fe QW up to12 nmthick and at\nroom temperature in fully epitaxial doubleMgAlOxbarrier magnetic tunnel\njunctions. The electron phase coherence displayed in this QWis of unprecedented\nquality because ofa homogenous interface phase shift due to the small lattice\nmismatch at the Fe/MgAlOx interface. The physical understanding of the critical\nrole of interface strain on QW phase coherence will greatly promote the\ndevelopment of the spin-dependent quantum resonant tunneling applications."
    },
    {
        "anchor": "Electrical detection of magnetic skyrmions by non-collinear\n  magnetoresistance: Magnetic skyrmions are localised non-collinear spin textures with high\npotential for future spintronic applications. Skyrmion phases have been\ndiscovered in a number of materials and a focus of current research is the\npreparation, detection, and manipulation of individual skyrmions for an\nimplementation in devices. Local experimental characterization of skyrmions has\nbeen performed by, e.g., Lorentz microscopy or atomic-scale tunnel\nmagnetoresistance measurements using spin-polarised scanning tunneling\nmicroscopy. Here, we report on a drastic change of the differential tunnel\nconductance for magnetic skyrmions arising from their non-collinearity: mixing\nbetween the spin channels locally alters the electronic structure, making a\nskyrmion electronically distinct from its ferromagnetic environment. We propose\nthis non-collinear magnetoresistance (NCMR) as a reliable all-electrical\ndetection scheme for skyrmions with an easy implementation into device\narchitectures.",
        "positive": "Conformal invariance of chiral edge theories: The low-energy effective quantum field theory of the edge excitations of a\nfully-gapped bulk topological phase corresponding to a local interaction\nHamiltonian must be local and unitary. Here it is shown that whenever all the\nedge excitations propagate in the same direction with the same velocity, it is\na conformal field theory. In particular, this is the case in the quantum Hall\neffect for model \"special Hamiltonians\", for which the ground state, quasihole,\nand edge excitations can be found exactly as zero-energy eigenstates, provided\nthe spectrum in the interior of the system is fully gapped. In addition, other\nconserved quantities in the bulk, such as particle number and spin, lead to\naffine Lie algebra symmetries in the edge theory. Applying the arguments to\nsome trial wavefunctions related to non-unitary conformal field theories, it is\nargued that the Gaffnian state and an infinite number of others cannot describe\na gapped topological phase because the numbers of edge excitations do not match\nany unitary conformal field theory."
    },
    {
        "anchor": "Frequency Adapted Phase Transition of Interacting Nano-Magnetic Ensemble: Each single domain nano-magnet acts as a magnetic dipole in addition it\noscillates its magnetization about the easy axis and rotates coherently\ndepending upon temperature and anisotropy. In an ensemble of nano-magnets, the\nrelaxation time of a nano-magnet tunes with the long range dipolar interaction\nwhich in turn is determined by the particle size, density and the number of\nnano-magnets present in the ensemble. Hence, the aggregation of interacting\nnano-magnetic dipoles, demonstrates both experimentally and theoretically as a\nmodel system to detect intriguing co-operative physical phenomena. Here we show\na new variant of phase transition from paramagnetic to diamagnetic phase by\nchanging the frequency of the applied sinusoidal magnetic field for a\nnano-magnetic ensemble. This phenomenon unravels a new insight of physics and\nit may be significant on the design and development of magnetic devices. The\nsimulation of the system is well in agreement with the experimental results.",
        "positive": "On Cherenkov Friction and Radiation of a Neutral Polarizable Particle\n  Moving Parallel to a Transparent Dielectric Plate: We have obtained general expressions for the intensity of radiation,\ndecelerating force, the rate of heating and acceleration of a small polarizable\nparticle under the conditions of Cherenkov friction: at relativistic motion\nparallel to the surface of thick transparent dielectric plate. Comparison with\nthe results of other authors is given."
    },
    {
        "anchor": "Molecular Simulation of Fracture Dynamics of Symmetric Tilt Grain\n  Boundaries in Graphene: Atomistic simulations were utilized to obtain microscopic information of the\nelongation process in graphene sheets consisting of various embedded symmetric\ntilt grain boundaries (GBs). In contrast to pristine graphene, these GBs\nfractured in an extraordinary pattern under transverse uniaxial elongation in\nall but the largest misorientation angle case, which exhibited intermittent\ncrack propagation and formed many stringy residual connections after quasi\nmechanical failure. The strings known as monoatomic carbon chains (MACCs),\nwhose importance was recently highlighted, gradually extended to a maximum of a\nfew nanometers as the elongation proceeded. These features, which critically\naffect the tensile stress and the shape of stress-strain curve, were observed\nin both armchair and zigzag-oriented symmetric tilt GBs. However, there exist\nremarkable differences in the population density and the achievable length of\nMACCs appearing after quasi mechanical failure which were higher in the\nzigzag-oriented GBs. In addition, the maximum stress and ultimate strain for\narmchair-oriented GBs were significantly greater than those of zigzag-oriented\nGBs in case of the largest misorientation angle while they were slightly\nsmaller in other cases. The maximum stress was larger as the misorientation\nangle increased for both armchair and zigzag-oriented GBs ranging between 32~80\nGPa, and the ultimate strains were between 0.06~0.11, the lower limit of which\nagrees very well with the experimental value of threshold strain beyond which\nmechanical failure often occurred in polycrystalline graphene.",
        "positive": "Visualizing topological insulating Bi2Te3 quintuple layers on\n  SiO2-capped Si substrates and its contrast optimization: Thin Bi2Te3 flakes, with as few as 3 quintuple layers, are optically\nvisualized on the SiO2-capped Si substrates. Their optical contrasts vary with\nthe illumination wavelength, flake thickness and capping layers. The maximum\ncontrast appears at the optimized light with the 570nm wavelength. The contrast\nturns reversed when the flake is reduced to less than 20 quintuple layers. A\ncalculation based on the Fresnel law describes the above observation with the\nconstructions of the layer number-wave length-contrast three-dimensional (3D)\ndiagram and the cap thickness-wavelength-contrast 3D diagram, applicative in\nthe current studies of topological insulating flakes."
    },
    {
        "anchor": "Influence of the Constant Electric Field on the Mutual Rectification of\n  the Electromagnetic Waves in Graphene Superlattice: In tight binding approximation the explicit form of the electron energy in\ngraphene superlattice was derived. The possibility of propagation of the\ncnoidal waves in graphene superlattice was discussed. The direct current\ninduced perpendicularly to the superlattice axis by cnoidal and sinusoidal\nelectromagnetic waves under the presence of longitudinal constant electric\nfield was calculated. Such direct current was shown to change its direction\nwhen the intensity of longitudinal electric field changes its absolute value.",
        "positive": "Joule heating induced negative differential resistance in free standing\n  metallic carbon nanotubes: The features of the $IV$ characteristics of metallic carbon nanotubes (m-NTs)\nin different experimental setups are studied using semi-classical Boltzmann\ntransport equation together with the heat dissipation equation to account for\nsignificant thermal effects at high electric bias. Our model predicts that the\nshape of the m-NT characteristics is basically controlled by heat removal\nmechanisms. In particular we show that the onset of negative differential\nresistance in free standing nanotubes finds its origins in strong transport\nnonlinearities associated with poor heat removal unlike in substrate-supported\nnanotubes."
    },
    {
        "anchor": "Resistivity of inhomogeneous quantum wires: We study the effect of electron-electron interactions on the transport in an\ninhomogeneous quantum wire. We show that contrary to the well-known Luttinger\nliquid result, non-uniform interactions contribute substantially to the\nresistance of the wire. In the regime of weakly interacting electrons and\nmoderately low temperatures we find a linear in T resistivity induced by the\ninteractions. We then use the bosonization technique to generalize this result\nto the case of arbitrarily strong interactions.",
        "positive": "Doublons, topology and interactions in a one-dimensional lattice: We investigate theoretically the Bose-Hubbard version of the celebrated\nSu-Schrieffer-Heeger topological model, which essentially describes a\none-dimensional dimerized array of coupled oscillators with on-site\ninteractions. We study the physics arising from the whole gamut of possible\ndimerizations of the chain, including both the weakly and the strongly\ndimerized limiting cases. Focusing on two-excitation subspace, we\nsystematically uncover and characterize the different types of states which may\nemerge due to the competition between the inter-oscillator couplings, the\nintrinsic topology of the lattice, and the strength of the on-site\ninteractions. In particular, we discuss the formation of scattering bands full\nof extended states, bound bands full of two-particle pairs (including so-called\n`doublons', when the pair occupies the same lattice site), and different\nflavors of topological edge states. The features we describe may be realized in\na plethora of systems, including nanoscale architectures such as photonic\ncavities and optical lattices, and provide perspectives for topological\nmany-body physics."
    },
    {
        "anchor": "Transporting a single-spin qubit through a double quantum dot: Coherent spatial transport or shuttling of a single electron spin through\nsemiconductor nanostructures is an important ingredient in many spintronic and\nquantum computing applications. In this work we analyze the possible errors in\nsolid-state quantum computation due to leakage in transporting a single-spin\nqubit through a semiconductor double quantum dot. In particular, we consider\nthree possible sources of leakage errors associated with such transport: finite\nramping times, spin-dependent tunneling rates between quantum dots induced by\nfinite spin-orbit couplings, and the presence of multiple valley states. In\neach case we present quantitative estimates of the leakage errors, and discuss\nhow they can be minimized. Moreover, we show that in order to minimize leakage\nerrors induced by spin-dependent tunnelings, it is necessary to apply pulses to\nperform certain carefully designed spin rotations. We further develop a\nformalism that allows one to systematically derive constraints on the pulse\nshapes and present a few examples to highlight the advantage of such an\napproach.",
        "positive": "Equilibrium free energy measurement of a confined electron driven out of\n  equilibrium: We study out-of equilibrium properties of a quantum dot in a GaAs/AlGaAs\ntwo-dimensional electron gas. By means of single electron counting experiments,\nwe measure the distribution of work and dissipated heat of the driven quantum\ndot and relate these quantities to the equilibrium free energy change, as it\nhas been proposed by C. Jarzynski [Phys. Rev. Lett. {\\bf78}, 2690 (1997)]. We\ndiscuss the influence of the degeneracy of the quantized energy state on the\nfree energy change as well as its relation to the tunnel rates between the dot\nand the reservoir."
    },
    {
        "anchor": "Floquet engineering flat bands for bosonic fractional quantum Hall in\n  small lattices: The quest to realize novel phases of matter with topological order is an\nimportant pursuit with implications for strongly correlated physics and quantum\ninformation. Utilizing ideas from state-of-the-art coherent control of\nartificial quantum systems such as superconducting circuits, we present a\nproposal to realize bosonic fractional quantum Hall physics on small lattices\nby creating nearly flat topological bands using staggered flux patterns.\nFingerprints of fractionalization through charge pumping can be observed with\nnearly perfect quantization using as few as 24 lattice sites (two photons). We\nsuggest an implementation using a finite lattice of superconducting qubits with\ncylindrical connectivity on both triangular and square lattices.",
        "positive": "Magnetic noise from ultra-thin abrasively deposited materials on diamond: Sensing techniques based on the negatively charged nitrogen-vacancy (NV)\ncentre in diamond have emerged as promising candidates to characterise\nultra-thin and 2D materials. An outstanding challenge to this goal is isolating\nthe contribution of 2D materials from undesired contributions arising from\nsurface contamination, and changes to the diamond surface induced by the sample\nor transfer process. Here we report on such a scenario, in which the abrasive\ndeposition of trace amounts of materials onto a diamond gives rise to a\npreviously unreported source of magnetic noise. By deliberately scratching the\ndiamond surface with macroscopic blocks of various metals (Fe, Cu, Cr, Au), we\nare able to form ultra-thin structures (i.e. with thicknesses down to\n$<1$\\,nm), and find that these structures give rise to a broadband source of\nnoise. Explanation for these effects are discussed, including spin and charge\nnoise native to the sample and/or induced by sample-surface interactions, and\nindirect effects, where the deposited material affects the charge stability and\nmagnetic environment of the sensing layer. This work illustrates the high\nsensitivity of NV noise spectroscopy to ultra-thin materials down to sub-nm\nregimes -- a key step towards the study of 2D electronic systems -- and\nhighlights the need to passivate the diamond surface for future sensing\napplications in ultra-thin and 2D materials."
    },
    {
        "anchor": "Non-Ohmic Coulomb drag in the ballistic electron transport regime: We work out a theory of the Coulomb drag current created under the ballistic\ntransport regime in a one-dimensional nanowire by a ballistic non-Ohmic current\nin a nearby parallel nanowire. As in the Ohmic case, we predict sharp\noscillation of the drag current as a function of gate voltage or the chemical\npotential of electrons. We study also dependence of the drag current on the\nvoltage V across the driving wire. For relatively large values of V the drag\ncurrent is proportional to V^2.",
        "positive": "Nanoscale rheology: Dynamic Mechanical Analysis over a broad and\n  continuous frequency range using Photothermal Actuation Atomic Force\n  Microscopy: Polymeric materials are widely used in industries ranging from automotive to\nbiomedical. Their mechanical properties play a crucial role in their\napplication and function and arise from the nanoscale structures and\ninteractions of their constitutive polymer molecules. Polymeric materials\nbehave viscoelastically, i.e. their mechanical responses depend on the time\nscale of the measurements; quantifying these time-dependent rheological\nproperties at the nanoscale is relevant to develop, for example, accurate\nmodels and simulations of those materials, which are needed for advanced\nindustrial applications. In this paper, an atomic force microscopy (AFM) method\nbased on the photothermal actuation of an AFM cantilever is developed to\nquantify the nanoscale loss tangent, storage modulus, and loss modulus of\npolymeric materials. The method is then validated on a styrene-butadiene rubber\n(SBR), demonstrating the method's ability to quantify nanoscale viscoelasticity\nover a continuous frequency range up to five orders of magnitude (0.2 Hz to\n20,200 Hz). Furthermore, this method is combined with AFM viscoelastic mapping\nobtained with amplitude-modulation frequency-modulation (AM-FM) AFM, enabling\nthe extension of viscoelastic quantification over an even broader frequency\nrange, and demonstrating that the novel technique synergizes with preexisting\nAFM techniques for quantitative measurement of viscoelastic properties. The\nmethod presented here introduces a way to characterize the viscoelasticity of\npolymeric materials, and soft matter in general at the nanoscale, for any\napplication."
    },
    {
        "anchor": "Powerful and efficient energy harvester with resonant-tunneling quantum\n  dots: We propose a nanoscale heat engine that utilizes the physics of resonant\ntunneling in quantum dots in order to transfer electrons only at specific\nenergies. The nanoengine converts heat into electrical current in a\nmultiterminal geometry which permits one to separate current and heat flows. By\nputting two quantum dots in series with a hot cavity, electrons that enter one\nlead are forced to gain a prescribed energy in order to exit the opposite lead,\ntransporting a single electron charge. This condition yields an ideally\nefficient heat engine. The energy gain is a property of the composite system\nrather than of the individual dots. It is therefore tunable to optimize the\npower while keeping a much larger level spacing for the individual quantum\ndots. Despite the simplicity of the physical model, the optimized rectified\ncurrent and power is larger than any other candidate nano-engine. The ability\nto scale the power by putting many such engines into a two-dimensional layered\nstructure gives a paradigmatic system for harvesting thermal energy at the\nnanoscale. We demonstrate that the high power and efficiency of the layered\nstructure persists even if the quantum dots exhibit some randomness.",
        "positive": "Retrieving the quantitative chemical information at nanoscale from SEM\n  EDX measurements by Machine Learning: The quantitative composition of metal alloy nanowires on InSb(001)\nsemiconductor surface and gold nanostructures on germanium surface is\ndetermined by blind source separation (BSS) machine learning (ML) method using\nnon negative matrix factorization (NMF) from energy dispersive X-ray\nspectroscopy (EDX) spectrum image maps measured in a scanning electron\nmicroscope (SEM). The BSS method blindly decomposes the collected EDX spectrum\nimage into three source components, which correspond directly to the X-ray\nsignals coming from the supported metal nanostructures, bulk semiconductor\nsignal and carbon background. The recovered quantitative composition is\nvalidated by detailed Monte Carlo simulations and is confirmed by separate\ncross-sectional TEM EDX measurements of the nanostructures. This shows that SEM\nEDX measurements together with machine learning blind source separation\nprocessing could be successfully used for the nanostructures quantitative\nchemical composition determination."
    },
    {
        "anchor": "Addition spectrum, persistent current, and spin polarization in coupled\n  quantum dot arrays: coherence, correlation, and disorder: The ground state persistent current and electron addition spectrum in\ntwo-dimensional quantum dot arrays and one-dimensional quantum dot rings,\npierced by an external magnetic flux, are investigated using the extended\nHubbard model. The collective multidot problem is shown to map exactly into the\nstrong field noninteracting finite-size Hofstadter butterfly problem at the\nspin polarization transition. The finite size Hofstadter problem is discussed,\nand an analytical solution for limiting values of flux is obtained. In weak\nfields we predict novel flux periodic oscillations in the spin component along\nthe quantization axis with a periodicity given by $\\nu h/e$ ($\\nu \\le 1$). The\nsensitivity of the calculated persistent current to interaction and disorder is\nshown to reflect the intricacies of various Mott-Hubbard quantum phase\ntransitions in two- dimensional systems: the persistent current is suppressed\nin the antiferromagnetic Mott-insulating phase governed by intradot Coulomb\ninteractions; the persistent current is maximized at the spin density wave -\ncharge density wave transition driven by the nearest neighbor interdot\ninteraction; the Mott-insulating phase persistent current is enhanced by the\nlong-range interdot interactions to its noninteracting value; the strong\nsuppression of the noninteracting current in the presence of random disorder is\nseen only at large disorder strengths; at half filling even a relatively weak\nintradot Coulomb interaction enhances the disordered noninteracting system\npersistent current; in general, the suppression of the persistent current by\ndisorder is less significant in the presence of the long-range interdot Coulomb\ninteraction.",
        "positive": "Electroluminescence of monolayer WS$_2$ in a scanning tunneling\n  microscope: the effect of bias polarity on the spectral and angular\n  distribution of the emitted light: Inelastic electron tunneling in a scanning tunneling microscope (STM) is used\nto generate excitons in monolayer tungsten disulfide (WS$_2$). Excitonic\nelectroluminescence is measured both at positive and negative sample bias.\nUsing optical spectroscopy and Fourier-space optical microscopy, we show that\nthe bias polarity of the tunnel junction determines the spectral and angular\ndistribution of the emitted light. At positive sample bias, only emission from\nexcitonic species featuring an in-plane transition dipole moment is detected.\nBased on the spectral distribution of the emitted light, we infer that the\ndominant contribution is from charged excitons, i.e., trions. At negative\nsample bias, additional contributions from lower-energy excitonic species are\nevidenced in the emission spectra and the angular distribution of the emitted\nlight reveals a mixed character of in-plane and out-of-plane transition dipole\nmoments."
    },
    {
        "anchor": "Vibrational cooling and thermoelectric response of nanoelectromechanical\n  systems: An important goal in nanoelectromechanics is to cool the vibrational motion,\nideally to its quantum ground state. Cooling by an applied charge current is a\nparticularly simple and hence attractive strategy to this effect. Here, we\nexplore this phenomenon in the context of the general theory of\nthermoelectrics. In linear response, this theory describes thermoelectric\nrefrigerators in terms of their cooling efficiency and figure of merit ZT. We\nshow that both concepts carry over to phonon cooling in nanoelectromechanical\nsystems. As an important consequence, this allows us to discuss the efficiency\nof phonon refrigerators in relation to the fundamental Carnot efficiency. We\nillustrate these general concepts by thoroughly investigating a simple\ndouble-quantum-dot model with the dual advantage of being quite realistic\nexperimentally and amenable to a largely analytical analysis theoretically.\nSpecifically, we obtain results for the efficiency, the figure of merit, and\nthe effective temperature of the vibrational motion in two regimes. In the\nquantum regime in which the vibrational motion is fast compared to the\nelectronic degrees of freedom, we can describe the electronic and phononic\ndynamics of the model in terms of master equations. In the complementary\nclassical regime of slow vibrational motion, the dynamics is described in terms\nof an appropriate Langevin equation. Remarkably, we find that the efficiency\ncan approach the maximal Carnot value in the quantum regime, with large\nassociated figures of merit. In contrast, the efficiencies are typically far\nfrom the Carnot limit in the classical regime. Our theoretical results should\nprovide guidance to implementing efficient vibrational cooling of\nnanoelectromechanical systems in the laboratory.",
        "positive": "Low Barrier Nanomagnets as p-bits for Spin Logic: It has recently been shown that a suitably interconnected network of tunable\ntelegraphic noise generators or \"p-bits\" can be used to perform even precise\narithmetic functions like a 32-bit adder. In this paper we use simulations\nbased on the stochastic Landau-Lifshitz-Gilbert (sLLG) equation to demonstrate\nthat similar impressive functions can be performed using unstable nanomagnets\nwith energy barriers as low as a fraction of a kT. This is surprising since the\nmagnetization of low barrier nanomagnets is not telegraphic with discrete\nvalues of +1 and -1. Rather it fluctuates randomly among all values between -1\nand +1, and the output magnets are read with a thresholding device that\ntranslates all positive values to 1 and all negative values to zero. We present\nsLLG-based simulations demonstrating the operation of a 32-bit adder with a\nnetwork of several hundred nanomagnets, exhibiting a remarkably precise\ncorrelation: The input magnets {A} and {B} as well as the output magnets {S}\nall fluctuate randomly and yet the quantity A+B-S is sharply peaked around\nzero! If we fix {A} and {B}, the sum magnets {S} rapidly converge to a unique\nstate with S=A+B so that the system acts as an adder. But unlike standard\nadders, the operation is invertible. If we fix {S} and {B}, the remaining\nmagnets {A} converge to the difference A=S-B. These examples suggest a new\ndirection for the field of nanomagnetics away from stable high barrier magnets\ntowards stochastic low barrier magnets which not only operate with lower\ncurrents, but are also more promising for continued downscaling."
    },
    {
        "anchor": "Novel Circuit Theory of Andreev Reflection: We review here a novel circuit theory of superconductivity. The existed\ncircuit theory of Andreev reflection has been revised to account for\ndecoherence between electrons and holes and twofold nature of the distribution\nfunction. The description of arbitrary connectors has been elaborated. In this\nway one can cope with the most of the factors that limited applicability of the\nold circuit theory. We give a simple example and discuss numerical\nimplementation of the theory.",
        "positive": "Goos-H\u00e4nchen Shifts in Gapped Graphene subject to External Fields: We study Dirac fermions in gapped graphene that are subjected to a magnetic\nfield and a potential barrier harmonically oscillating in time. The tunneling\nmodes inside the gap and the associated Goos-H\\\"anchen (GH) shifts are\nanalytically investigated. We show that the GH shifts in transmission for the\ncentral band and the first two sidebands change sign at the Dirac points\n$\\epsilon+l\\hbar\\tilde{\\omega}$ $(l=0,\\pm 1)$. We also find that the GH shifts\ncan be either negative or positive and becomes zero at transmission resonances."
    },
    {
        "anchor": "Tunable Kondo physics in a carbon nanotube double quantum dot: We investigate a tunable two-impurity Kondo system in a strongly correlated\ncarbon nanotube double quantum dot, accessing the full range of charge regimes.\nIn the regime where both dots contain an unpaired electron, the system\napproaches the two-impurity Kondo model. At zero magnetic field the interdot\ncoupling disrupts the Kondo physics and a local singlet state arises, but we\nare able to tune the crossover to a Kondo screened phase by application of a\nmagnetic field. All results show good agreement with a numerical\nrenormalization group study of the device.",
        "positive": "Fabrication and Electric Field Dependent Transport Measurements of\n  Mesoscopic Graphite Devices: We have developed a unique micromechanical method to extract extremely thin\ngraphite samples. Graphite crystallites with thicknesses ranging from 10 - 100\nnm and lateral size $\\sim$ 2 $\\mu$m are extracted from bulk. Mesoscopic\ngraphite devices are fabricated from these samples for electric field dependent\nconductance measurements. Strong conductance modulation as a function of gate\nvoltage is observed in the thinner crystallite devices. The temperature\ndependent resistivity measurements show more boundary scattering contribution\nin the thinner graphite samples."
    },
    {
        "anchor": "The Progresses of preparation and modification of graphene on substrate: It is significant to prepare large area of high quality graphene for the\nstudy of the characteristics of graphene and the research of the nano-devices\nbased on graphene. This paper summarizes the experiment progresses and\nmechanism of graphene grown on different substrates. Nowadays, we can obtain\nthe large area of high quality graphene by using the methods, such as CVD,\nepitaxial growth, etc. The interaction between the graphene and the substrates\nis closely related to the mismatch of the lattice, weakness of the bonds and\nthe transformation of the electrons, which has a great influence on geometry,\nenergy band and the properties of electrons of the graphene. The combination of\nthe experiment and the calculation can make deeper understanding of the\nmechanism of the effects between graphene and different substrates, which can\nbe served as a guide for further study.",
        "positive": "Broadband Femtosecond Transient Absorption Spectroscopy for CVD MoS2\n  monolayer: Carrier dynamics in monolayer MoS2 have been investigated using broadband\nfemtosecond transient absorption spectroscopy (FTAS). A tunable pump pulse was\nused while a broadband probe pulse revealed ground and excited state carrier\ndynamics. Interestingly, for pump wavelengths both resonant and non-resonant\nwith the A and B excitons, we observe a broad ground state bleach around 2.9\neV, with decay components similar to A and B. Associating this bleach with the\nband nesting region between K and Gamma in the band structure indicates\nsignificant k-space delocalization and overlap among excitonic wave functions\nidentified as A, B, C, and D. Comparison of time dynamics for all features in\nresonance and non-resonance excitation is consistent with this finding."
    },
    {
        "anchor": "Scanned Potential Microscopy of Edge States in a Quantum Hall Liquid: Using a low-temperature atomic force microscope as a local voltmeter, we\nmeasure the Hall voltage profile in a quantum Hall conductor in the presence of\na gate-induced non-equilibrium edge state population at n=3. We observe sharp\nvoltage drops at the sample edges which are suppressed by re-equilibrating the\nedge states.",
        "positive": "Nonequilibrium phases and phase transitions of the XY-model: We obtain the steady-state phase diagram of a transverse field XY spin chain\ncoupled at its ends to magnetic reservoirs held at different magnetic\npotentials. In the long-time limit, the magnetization bias across the system\ngenerates a current-carrying non-equilibrium steady-state. We characterize the\ndifferent non-equilibrium phases as functions of the chain's parameters and\nmagnetic potentials, in terms of their correlation functions and entanglement\ncontent. The mixed-order transition, recently observed for the particular case\nof a transverse field Ising chain, is established to emerge as a generic\nout-of-equilibrium feature and its critical exponents are determined\nanalytically. Results are also contrasted with those obtained in the limit of\nMarkovian reservoirs. Our findings should prove helpful in establishing the\nproperties of non-equilibrium phases and phase transitions of extended open\nquantum systems."
    },
    {
        "anchor": "Dispersion and damping of multi-quantum well polaritons from resonant\n  Brillouin scattering by folded acoustic modes: We report on confined exciton resonances of acoustic and folded acoustic\nphonon light scattering in a GaAs/AlAs multi-quantum-well. Significant\nvariations of the line shifts and widths are observed across the resonance and\nquantitatively reproduced in terms of the polariton dispersion. This high\nresolution Brillouin study brings new unexpectedly detailed informations on the\npolariton dynamics in confined systems.",
        "positive": "Extremely high-resolution measurements of microwave magnetisation\n  dynamics in magnetic thin films and nanostructures: In this work we discuss the use of interferometric measurement technique to\nstudy microwave magnetization dynamics on ferromagnetic nanostructures. We\ndemonstrate that in this way one can resolve features which are impossible to\nresolve with broadband ferromagnetic resonance and traveling spin wave\nspectroscopy otherwise."
    },
    {
        "anchor": "Ab initio k.p theory of spin-momentum locking: Application to\n  topological surface states: Based on ab initio relativistic ${\\mathbf k}\\cdot{\\mathbf p}$ theory, we\nderive an effective two-band model for surface states of three-dimensional\ntopological insulators up to seventh order in $\\mathbf{k}$. It provides a\ncomprehensive description of the surface spin structure characterized by a\nnon-orthogonality between momentum and spin. We show that the oscillation of\nthe non-orthogonality with the polar angle of $\\mathbf{k}$ with a $\\pi/3$\nperiodicity can be seen as due to effective six-fold symmetric spin-orbit\nmagnetic fields with a quintuple and septuple winding of the field vectors per\nsingle rotation of $\\mathbf{k}$. Owing to the dominant effect of the classical\nRashba field, there remains a single-winding helical spin structure but with a\nperiodic few-degree deviation from the orthogonal locking between momentum and\nspin.",
        "positive": "Screening and gap generation in bilayer graphene: A fully selfconsistent treatment for gap generation and Coulomb screening in\nexcitonic insulators is presented. The method is based on the equations of\nmotion for the relevant dynamical variables combined with a variational\napproach. Applying the theory for a model system of bilayer graphene, an\nexcitonic groundstate with a gap exceeding 10 meV is predicted."
    },
    {
        "anchor": "Effects of Non-Hermiticity on Su-Schrieffer-Heeger Defect States: We study the emergence and disappearance of defect states in the complex\nSu-Schrieffer-Heeger (cSSH) model, a non-Hermitian one-dimensional lattice\nmodel containing gain and loss on alternating sites. Previous studies of this\nmodel have focused on the existence of a non-Hermitian defect state that is\nlocalized to the interface between two cSSH domains, and is continuable to the\ntopologically protected defect state of the Hermitian Su-Schrieffer-Heeger\n(SSH) model. For large gain/loss magnitudes, we find that these defect states\ncan disappear into the continuum, or undergo pairwise spontaneous breaking of a\ncomposite sublattice/time-reversal symmetry. The symmetry-breaking transition\ngives rise to a pair of defect states continuable to\nnon-topologically-protected defect states of the SSH model. We discuss the\nphase diagram for the defect states, and its implications for non-Hermitian\ndefect states.",
        "positive": "Tunnelling through a semiconducting spacer: complex band predictions vs.\n  thin film calculations: Using a simple tight-binding model, we compare the limitations of the\ntunnelling predictions coming out of the complex band structure of a\nsemiconductor with the output of thin film calculations done for the same\nsemiconducting spacer but considering it to be of finite width, and sandwiched\nby metallic electrodes. The comparison is made as a function of spacer width\nand interfacial roughness."
    },
    {
        "anchor": "Localization and exact current compensation in the quantum Hall effect: A field-theoretic formulation of a planar Hall-electron system with edges is\npresented and some fundamental aspects of the integer quantum Hall effect are\nstudied with emphasis on clarifying general symmetry-based consequences of\nlocalization. It is shown, in particular, that the immobility of localized\nelectron states and current compensation by extended electron states, both\ncrucial for quantization of the Hall conductance, are derived through the\noperation of magnetic translation of localized electron states alone. They\nactually are consequences of gauge invariance and hold under general\ncircumstances with both level mixing and electron edge states taken into\naccount.",
        "positive": "Theory of Weyl orbital semimetals and predictions of several materials\n  classes: Graphene, topological insulators, and Weyl semimetals are three widely\nstudied materials classes which possess Dirac or Weyl cones arising from either\nsublattice symmetry or spin-orbit coupling. In this work, we present a theory\nof a new class of bulk Dirac and Weyl cones, dubbed Weyl orbital semimetals,\nwhere the orbital polarization and texture inversion between two electronic\nstates at discrete momenta lend itself into protected Dirac or Weyl cones\nwithout spin-orbit coupling. We also predict several families of Weyl orbital\nsemimetals including V$_3$S$_4$, NiTi3S6, BLi, and PbO$_2$ via first-principle\nband structure calculations. We find that the highest Fermi velocity predicted\nin some of these materials is even larger than that of the existing Dirac\nmaterials. The synthesis of Weyl orbital semimetals will not only expand the\nterritory of Dirac materials beyond the quintessential spin-orbit coupled\nsystems and hexagonal lattice to the entire periodic table, but it may also\nopen up new possibilities for orbital controlled electronics or `orbitronics'."
    },
    {
        "anchor": "Superconducting Quantum Interference in Edge State Josephson Junctions: We study superconducting quantum interference in a Josephson junction linked\nvia edge states in two-dimensional (2D) insulators. We consider two scenarios\nin which the 2D insulator is either a topological or a trivial insulator\nsupporting one-dimensional (1D) helical or nonhelical edge states,\nrespectively. In equilibrium, we find that the qualitative dependence of\ncritical supercurrent on the flux through the junction is insensitive to the\nhelical nature of the mediating states and can, therefore, not be used to\nverify the topological features of the underlying insulator. However, upon\napplying a finite voltage bias smaller than the superconducting gap to a\nrelatively long junction, the finite-frequency interference pattern in the\nnon-equilibrium transport current is qualitatively different for helical edge\nstates as compared to nonhelical ones.",
        "positive": "Dynamical second-order noise sweetspots in resonantly driven spin qubits: Quantum dot-based quantum computation employs extensively the exchange\ninteraction between nearby electronic spins in order to manipulate and couple\ndifferent qubits. The exchange interaction, however, couples the qubit states\nto charge noise, which reduces the fidelity of the quantum gates that employ\nit. The effect of charge noise can be mitigated by working at noise sweetspots\nin which the sensitivity to charge variations is reduced. In this work we study\nthe response to charge noise of a double quantum dot based qubit in the\npresence of ac gates, with arbitrary driving amplitudes, applied either to the\ndot levels or to the tunneling barrier. Tuning with an ac driving allows to\nmanipulate the sign and strength of the exchange interaction as well as its\ncoupling to environmental electric noise. Moreover, we show the possibility of\ninducing a second-order sweetspot in the resonant spin-triplet qubit in which\nthe dephasing time is significantly increased."
    },
    {
        "anchor": "Frequency dependence of the light-induced Hall effect in dissipative\n  graphene: We determine the Hall conductivity of light-driven graphene, with specific\nfocus on its frequency dependence, and compare it to the static effective\napproximation, based on Floquet states. This approximation gives the Haldane\nmodel as the effective model for light-driven graphene, with a gapped spectrum\nand a quantized Hall conductivity of $-2e^2/h$. We simulate both the\nlight-driven and the effective model, and explicitly include the dissipative\nenvironment in our simulations. We investigate the effect of different driving\nregimes and dissipation strengths on the Hall conductivity in graphene. As a\ncentral result, the Hall conductivity of the light-driven system is not well\napproximated by the effective model, except for a regime of intermediate\ndriving frequencies and small dissipation where the Hall conductivity\ncontribution of the Dirac point approximately recovers the quantized value of\n$-2e^2/h$, as well as in the transient dynamics for weak dissipation.",
        "positive": "Non-monotonic velocity dependence of atomic friction: We study the velocity dependence of the frictional force of the tip of an\natomic force microscope as it is dragged across a surface, taking into account\nmemory effects and thermal fluctuations. Memory effects are described by a\ncoupling of the tip to low frequency excitation modes of the surface in\naddition to the coupling to the periodic corrugation potential. We find that\nwhen the excitation mode frequency is comparable to the characteristic\nfrequency corresponding to the motion of the tip across the surface, the\nvelocity dependence of the frictional force is non monotonic, displaying a\nvelocity range where the frictional force can decrease with increasing\nvelocity. These results provide theoretical support for the interpretation of\nrecent experiments which find a frictional force that decreases with velocity\non surfaces covered with a monolayer."
    },
    {
        "anchor": "The critical transition of Coulomb impurities in gapped graphene: The effect of supercritical charge impurities in graphene is very similar to\nthe supercritical atomic collapses in QED for Z > 137, but with a much lower\ncritical charge. In this sense graphene can be considered as a natural testing\nground for the analysis of quantum field theory vacuum instabilities. We\nanalyze the quantum transition from subcritical to supercritical charge regimes\nin gapped graphene in a common framework that preserves unitarity for any value\nof charge impurities. In the supercritical regime it is possible to introduce\nboundary conditions which control the singular behavior at the impurity. We\nshow that for subcritical charges there are also non-trivial boundary\nconditions which are similar to those that appear in QED for nuclei in the\nintermediate regime 118<Z<137. We analyze the behavior of the energy levels\nassociated to the different boundary conditions. In particular, we point out\nthe existence of new bound states in the subcritical regime which include a\nnegative energy bound state in the attractive Coulomb regime. A remarkable\nproperty is the continuity of the energy spectral flow under variation of the\nimpurity charge even when jumping across the critical charge transition. We\nalso remark that the energy levels of Hydrogenoid bound states at critical\nvalues of charge impurities act as focal points of the spectral flow.",
        "positive": "Two-photon luminescence of single colloidal gold nanorods: revealing the\n  origin of plasmon relaxation in small nanocrystals: The two-photon luminescence (TPL) of small 10 nm x 40 nm colloidal gold\nnanorods (GNR) is investigated at the single object level, combining\npolarization resolved TPL and simultaneously acquired topography. A very high\ndependence of the TPL signal with both the nanorods longitudinal axis and the\nincident wavelength is observed confirming the plasmonic origin of the signal\nand pointing the limit of the analogy between GNRs and molecules. The spectral\nanalysis of the TPL evidences two emission bands peaks: in the visible (in\ndirect connection with the gold band structure), and in the infrared. Both\nbands are observed to vary quadradically with the incident excitation beam but\nexhibit different polarization properties. The maximum two-photon brightness of\na single GNR is measured to be a few millions higher than the two-photon\nbrightness of fluorescein molecules. We show that the important TPL observed in\nthese small gold nanorods results from resonance effects both at the excitation\nand emission level : local field enhancement at the longitudinal surface\nplasmon resonances (LSPR) first results in an increase of the electron-hole\ngeneration. Further relaxation of electron-hole pairs then mostly leads to the\nexcitation of the GNR transverse plasmon mode and its subsequent radiative\nrelaxation."
    },
    {
        "anchor": "Super Bloch oscillations in the Peyrard-Bishop-Holstein model: Recently, polarons in the Peyrard-Bishop-Holstein model under DC electric\nfields were established to perform Bloch oscillations, provided the\ncharge-lattice coupling is not large. In this work, we study this model when\nthe charge is subjected to an applied field with both DC and AC components.\nSimilarly to what happens in the rigid lattice, we find that the carrier\nundergoes a directed motion or coherent oscillations when the AC field is\nresonant or detuned with respect to the Bloch frequency, respectively. The\nelectric density current and its Fourier spectrum are also studied to reveal\nthe frequencies involved in the polaron dynamics.",
        "positive": "Chiral spin structure of electron gas in systems with magnetic skyrmions: The theoretical study considers chiral spin texture induced in a 2D electron\ngas (2DEG) by magnetic skyrmions. We calculate the electron gas spin density as\na linear response to the exchange interaction between the 2DEG and the\nmagnetization field of a magnetic skyrmion. Two physically distinct regimes\noccur. When the size of the skyrmion is larger than the inverse Fermi\nwavevector $k_F^{-1}$, the spin density response follows the magnetization\nprofile of the skyrmion. In the opposite case of a small skyrmion the emerging\nspin structure of 2DEG has a characteristic size of $k_F^{-1}$ and the response\nbecomes non-local, it can be viewed as chiral Friedel oscillations. At that,\nthe emerging spin structure of the oscillations appears to be more complex than\nthat of the skyrmion itself."
    },
    {
        "anchor": "All Optical Measurement Proposed for the Photovoltaic Hall Effect: We propose an all optical way to measure the recently proposed \"photovoltaic\nHall effect\", i.e., a DC Hall effect induced by a circularly polarized light in\nthe absence of static magnetic fields. For this, we have calculated the Faraday\nrotation angle induced by the photovoltaic Hall effect with the Kubo formula\nextended for photovoltaic optical response in the presence of strong AC\nelectric fields treated with the Floquet formalism. We also point out the\npossibility of observing the effect in three-dimensional graphite, and more\ngenerally in multi-band systems such as materials described by the dp-model.",
        "positive": "High temperature phase transition in the coupled atom-light system in\n  the presence of optical collisions: The problem of photonic phase transition for the system of a two-level atomic\nensemble interacting with a quantized single-mode electromagnetic field in the\npresence of optical collisions (OC) is considered. We have shown that for large\nand negative atom-field detuning a photonic field exhibits high temperature\nsecond order phase transition to superradiant state under thermalization\ncondition for coupled atom-light states. Such a transition can be connected\nwith superfluid (coherent) properties of photon-like low branch (LB)\npolaritons. We discuss the application of metallic cylindrical waveguide for\nobserving predicted effects."
    },
    {
        "anchor": "Comment on ``Quantum Suppression of Shot Noise in Atom-Size Metallic\n  Contacts'': In a recent letter (Phys.Rev.Lett. 82, 1526 (1999)), van den Brom and van\nRuitenbeek found a pronounced suppression of the shot noise in atom-size gold\ncontacts with conductances near integer multiples of $G_0=2e^2/h$, revealing\nunambiguously the quantized nature of the electronic transport. However, the ad\nhoc model they introduced to describe the contribution of partially-open\nconductance channels to the shot noise is unable to fit either the maxima or\nminima of their shot noise data. Here we point out that a model of\nquantum-confined electrons with disorder quantitatively reproduces their\nmeasurements.",
        "positive": "Two-dimensional electrons at a cleaved semiconductor surface:\n  Observation of the quantum Hall effect: Low-temperature in-plane magnetotransport measurements have been performed on\nadsorbate-induced electron systems formed at in-situ cleaved surfaces of p-type\nInAs. The Ag-coverage dependence of the surface electron density strongly\nsupports a simple model based on a surface donor level lying above the\nconduction band minimum. The observations of the quantized Hall resistance and\nzero longitudinal resistivity demonstrate the perfect two-dimensionality of the\nsurface electron system. We also observed the Rashba effect due to the strong\nasymmetry of the confining potential well."
    },
    {
        "anchor": "Field induced nucleation in the presence of a metal electrode: We consider the effect of metal electrodes on the polarizability and\nnucleation of metal phases responsible for the operations of the emerging solid\nstate memory. Our analysis is based on the image charge approach. We find\nresults for point dipoles in static and oscillatory fields as well as an erect\ncylindrical nucleus near metal surfaces in resistive switching memories. We\npredict a large increase in polarizability and nucleation rate due to the metal\nelectrode effects.",
        "positive": "Damping of a nanomechanical oscillator strongly coupled to a quantum dot: We present theoretical and experimental results on the mechanical damping of\nan atomic force microscope cantilever strongly coupled to a self-assembled InAs\nquantum dot. When the cantilever oscillation amplitude is large, its motion\ndominates the charge dynamics of the dot which in turn leads to nonlinear,\namplitude-dependent damping of the cantilever. We observe highly asymmetric\nlineshapes of Coulomb blockade peaks in the damping that reflect the degeneracy\nof energy levels on the dot, in excellent agreement with our strong coupling\ntheory. Furthermore, we predict that excited state spectroscopy is possible by\nstudying the damping versus oscillation amplitude, in analogy to varying the\namplitude of an ac gate voltage."
    },
    {
        "anchor": "Magnetic Reversal in Nanoscopic Ferromagnetic Rings: We present a theory of magnetization reversal due to thermal fluctuations in\nthin submicron-scale rings composed of soft magnetic materials. The\nmagnetization in such geometries is more stable against reversal than that in\nthin needles and other geometries, where sharp ends or edges can initiate\nnucleation of a reversed state. The 2D ring geometry also allows us to evaluate\nthe effects of nonlocal magnetostatic forces. We find a `phase transition',\nwhich should be experimentally observable, between an Arrhenius and a\nnon-Arrhenius activation regime as magnetic field is varied in a ring of fixed\nsize.",
        "positive": "Mechanical entanglement detection in an optomechanical system: We propose here a setup to generate and evaluate the entanglement between two\nmechanical resonators in a cavity optomechanical setting. As in previous\nproposals, our scheme includes two driving pumps allowing for the generation of\ntwo-mode mechanical squeezing. In addition, we include here four additional\nprobing tones, which allow for the separate evaluation of the collective\nmechanical quadratures required to estimate the Duan quantity, thus allowing us\nto infer whether the mechanical resonators are entangled."
    },
    {
        "anchor": "Non-local Andreev reflection through Andreev molecular states in\n  graphene Josephson junctions: We propose that a device composed of two vertically stacked monolayer\ngraphene Josephson junctions can be used for Cooper pair splitting. The\nhybridization of the Andreev bound states of the two Josephson junction can\nfacilitate non-local transport in this normal-superconductor hybrid structure,\nwhich we study by calculating the non-local differential conductance. Assuming\nthat one of the graphene layers is electron and the other is hole doped, we\nfind that the non-local Andreev reflection can dominate the differential\nconductance of the system. Our setup does not require the precise control of\njunction length, doping, or superconducting phase difference, which could be an\nimportant advantage for experimental realization.",
        "positive": "Trial wavefunctions for the Goldstone mode in \u03bd=1/2+1/2 quantum Hall\n  bilayers: Based on the known physics of the excitonic superfluid or 111 state of the\nquantum Hall \\nu=1/2+1/2 bilayer, we create a simple trial wavefunction ansatz\nfor constructing a low energy branch of (Goldstone) excitations by taking the\noverall ground state and boosting one layer with respect to the other. This\nansatz works extremely well for any interlayer spacing. For small d this is\nsimply the physics of the Goldstone mode, whereas for large d this is a\nreflection of composite fermion physics. We find hints that certain aspects of\ncomposite fermion physics persist to low d whereas certain aspects of Goldstone\nmode physics persist to high d. Using these results we show nonmonotonic\nbehavior of the Goldstone mode velocity as a function of d."
    },
    {
        "anchor": "Unconventional Quantum Hall Effect and Tunable Spin Hall Effect in MoS2\n  Trilayers: We analyze the Landau level (LL) structure and spin Hall effect in a MoS2\ntrilayer. Due to orbital asymmetry, the low-energy Dirac fermions become\nheavily massive and the LL energies grow linearly with $B$, rather than with\n$\\sqrt{B}$. Spin-orbital couplings break spin and valley degenerate LL's into\ntwo time reversal invariant groups, with LL crossing effects present in the\nvalence bands. We find a field-dependent unconventional Hall plateau sequence\n$\\nu=...$ $-2M-6$, $-2M-4$, $-2M-2$, $-2M-1$, ..., -5, -3, -1, 0, 2, 4 .... In\na p-n junction, spin-resolved fractionally quantized conductance appears in\ntwo-terminal measurements with a controllable spin-polarized current that can\nbe probed at the interface. We also show the tunability of zero-field spin Hall\nconductivity.",
        "positive": "Hall conductivity as the topological invariant in magnetic Brillouin\n  zone: Hall conductivity for the intrinsic quantum Hall effect in homogeneous\nsystems is given by the topological invariant composed of the Green function\ndepending on momentum of quasiparticle. This expression reveals correspondence\nwith the mathematical notion of the degree of mapping. A more involved\nsituation takes place for the Hall effect in the presence of external magnetic\nfield. In this case the mentioned expression remains valid if the Green\nfunction is replaced by its Wigner transformation while ordinary products are\nreplaced by the Moyal products. Such an expression, unfortunately, is much more\ncomplicated and might be useless for the practical calculations. Here we\nrepresent the alternative representation for the Hall conductivity of a uniform\nsystem in the presence of constant magnetic field. The Hall conductivity is\nexpressed through the Green function taken in Harper representation, when its\nnonhomogeneity is attributed to the matrix structure while functional\ndependence is on one momentum that belongs to magnetic Brillouin zone. Our\nresults were obtained for the non - interacting systems. But we expect that\nthey remain valid for the interacting systems as well. We, therefore, propose\nthe hypothesis that the obtained expression may be used for the topological\ndescription of fractional quantum Hall effect."
    },
    {
        "anchor": "Optical dipole orientation of interlayer excitons in\n  MoSe$_{2}$-WSe$_{2}$ heterostacks: We report on the far-field photoluminescence intensity distribution of\ninterlayer excitons in MoSe$_{2}$-WSe$_{2}$ heterostacks as measured by back\nfocal plane imaging in the temperature range between 1.7 K and 20 K. By\ncomparing the data with an analytical model describing the dipolar emission\npattern in a dielectric environment, we are able to obtain the relative\ncontributions of the in- and out-of-plane transition dipole moments associated\nto the interlayer exciton photon emission. We determine the transition dipole\nmoments for all observed interlayer exciton transitions to be (99 $\\pm$ 1)%\nin-plane for R- and H-type stacking, independent of the excitation power and\ntherefore the density of the exciton ensemble in the experimentally examined\nrange. Finally, we discuss the limitations of the presented measurement\ntechnique to observe correlation effects in exciton ensembles.",
        "positive": "Effective Mass of the Four Flux Composite Fermion at $\u03bd= 1/4$: We have measured the effective mass ($m^*$) of the four flux composite\nfermion at Landau level filling factor $\\nu = 1/4$ ($^4$CF), using the\nactivation energy gaps at the fractional quantum Hall effect (FQHE) states\n$\\nu$ = 2/7, 3/11, and 4/15 and the temperature dependence of the Shubnikov-de\nHaas (SdH) oscillations around $\\nu = 1/4$. We find that the energy gaps show a\nlinear dependence on the effective magnetic field $B_{eff}$ ($\\equiv\nB-B_{\\nu=1/4}$), and from this linear dependence we obtain $m^* = 1.0 m_e$ and\na disorder broadening $\\Gamma \\sim$ 1 K for a sample of density $n = 0.87\n\\times 10^{11}$ /cm$^2$. The $m^*$ deduced from the temperature dependence of\nthe SdH effect shows large differences for $\\nu > 1/4$ and $\\nu < 1/4$. For\n$\\nu > 1/4$, $m^* \\sim 1.0 m_e$. It scales as $\\sqrt{B_{\\nu}}$ with the mass\nderived from the data around $\\nu =1/2$ and shows an increase in $m^*$ as $\\nu\n\\to 1/4$, resembling the findings around $\\nu =1/2$. For $\\nu < 1/4$, $m^*$\nincreases rapidly with increasing $B_{eff}$ and can be described by $m^*/m_e =\n-3.3 + 5.7 \\times B_{eff}$. This anomalous dependence on $B_{eff}$ is\nprecursory to the formation of the insulating phase at still lower filling."
    },
    {
        "anchor": "Fractional Josephson effect versus fractional charge in\n  superconducting-normal metal hybrid circuits: Fractionally charged excitations play a central role in condensed matter\nphysics, and can be probed in different ways. If transport occurs via\ndissipation-less supercurrents, they manifest as a fractional Josephson effect,\nwhereas in dissipative transport they can be revealed by the transport\nstatistics. However, in a regime where supercurrents and lossy currents\ncoincide, a full understanding of the relationship between these two transport\nphenomena is still missing. Moreover, especially for superconducting circuits,\nthe question of how noninteger quasicharges can be reconciled with charge\nquantization is still not fully resolved, and plays an important role for the\ncircuit dynamics. Here, we aim to unify the above concepts by studying the\nsystem-detector dynamics in terms of a Lindbladian capturing both coherent and\ndissipative transport. Charge quantization is here a conserved property of the\ndetector basis of the Lindbladian, while charge fractionalization is a\ntopological property of its complex-valued eigenspectrum. We show that already\nconventional superconductor-normal metal hybrid circuits exhibit a variety of\ntopological phases, including an open quantum system version of a fractional\nJosephson effect. Surprisingly, quasiparticles, usually considered a\ndetrimental side effect, are here a necessary ingredient to observe nontrivial\ntransport behaviour.",
        "positive": "Gate modulation of the hole singlet-triplet qubit frequency in germanium: Spin qubits in germanium gate-defined quantum dots have made considerable\nprogress within the last few years, partially due to their strong spin-orbit\ncoupling and site-dependent $g$-tensors. While this characteristic of the\n$g$-factors removes the need for micromagnets and allows for the possibility of\nall-electric qubit control, relying on these $g$-tensors necessitates the need\nto understand their sensitivity to the confinement potential that defines the\nquantum dots. Here, we demonstrate a $S-T\\_$ qubit whose frequency is a strong\nfunction of the voltage applied to the barrier gate shared by the quantum dots.\nWe find a $g$-factor that can be approximately increased by an order of\nmagnitude adjusting the barrier gate voltage only by 12 mV. We attribute the\nstrong dependence to a variable strain profile in our device. This work not\nonly reinforces previous findings that site-dependent $g$-tensors in germanium\ncan be utilized for qubit manipulation, but reveals the sensitivity and\ntunability these $g$-tensors have to the electrostatic confinement of the\nquantum dot."
    },
    {
        "anchor": "Cyclotron- and magnetoplasmon resonances in bilayer graphene ratchets: We report on a tunable - by magnetic field and gate voltage - conversion of\nterahertz radiation into a dc current in spatially modulated bilayer graphene.\nWe experimentally demonstrate that the underlying physics is related to the\nso-called ratchet effect. Our key findings are the direct observation of a\nsharp cyclotron resonance in the photocurrent and the demonstration of two\neffects caused by electron-electron interaction: the plasmonic splitting of the\nresonance due to long-range Coulomb coupling and the partial suppression of its\nsecond harmonic due to fast interparticle collisions. We develop a theory which\nperfectly fits our data. We argue that the ratchet current is generated in the\nhydrodynamic regime of non-ideal electron liquid.",
        "positive": "Edge-dependent electronic and magnetic characteristics of freestanding\n  \u03b2_12-Borophene Nanoribbons: Nanoribbons produced from cutting {\\beta}_12-Borophene sheet is investigated\nby density functional theory. The electronic and magnetic properties of\nBorophene nanoribbons are studied and found that all considered ribbons are\nmetal which is in good agreement with recent experimental results.\n{\\beta}_12-Borophene nanoribbons have a lot of diversity due to existence of 5\nBoron atoms in a unit cell of the sheet. The magnetic properties of ribbons are\nstrongly dependent on the cutting direction and the edge profile. It is\ninteresting that a ribbon with a specific width can be a normal or\nferromagnetic metal with magnetization in just one edge or two edges. The spin\nanisotropy is observed in some ribbons so that magnetic moment is not the same\nin both edges in antiferromagnetic configuration. The effect comes from the\nedge asymmetry of the ribbons and results in the breaking of spin degeneracy in\nthe bandstructure. Our findings show that {\\beta}_12 nanoribbons are potential\ncandidates for next-generation spintronic devices."
    },
    {
        "anchor": "Effect of ferromagnetic exchange field on band-gap and spin-polarization\n  of graphene on a TMD substrate: We calculate the electronic band dispersion of graphene monolayer on a two\ndimensional transition metal dichalcogenide substrate (GTMD) (viz., XY2 , X =\nMo, W; Y = S, Se) around K and K prime points taking into account the interplay\nof the exchange field due to the ferromagnetic impurities and the substrate\ninduced, sub-lattice-resolved, strongly enhanced intrinsic spin-orbit\ncouplings(SOC). There are extrinsic Rashba spin-orbit coupling(RSOC) and the\norbital gap related to the transfer of the electronic charge from graphene to\nXY2 as well. The former allows for external tuning of the band gap in GTMD and\nconnects the nearest neighbors with spin-flip. On account of the strong SOC,\nthe system acts as a quantum spin Hall insulator. We introduce the exchange\nfield (M) in the Hamiltonian to take into account the deposition of Fe atoms on\nthe graphene surface. The cavalcade of the perturbations yield particle-hole\nsymmetric bands with an effective Zeeman field due to the interplay of the\nsubstrate induced interactions with RSOC as the prime player. Our graphical\nanalysis with extremely low-lying states strongly suggests the following: The\nGTMDs like WY2 exhibit band gap narrowing/widening (Moss-Burs-tein(MB)gap\nshift)including the spin-polarization inversion(SPI) at finite but low\ntemperature (T = 1 K) due to the increase in the exchange field (M) at the\nDirac point K. For graphene on MoY2, on the other hand, the occurrence of the\nMB-shift and the SPI at higher temperature (T = 10 K) take place as M is\nincreased at the Dirac point K prime. Finally, there is anti-crossing of\nnon-parabolic bands with opposite spins around Dirac points. A direct electric\nfield control of magnetism at the nano-scale is needed here. The magnetic\nmulti-ferroics, like BiFeO3 (BFO), are useful for this purpose due to the\ncoupling between the magnetic and electric order parameters.",
        "positive": "Bias induced circular spin current: Effects of environmental dephasing\n  and disorder: Analogous to circular spin current in an isolated quantum loop, bias induced\nspin circular current can also be generated under certain physical conditions\nin a nanojunction having single and/or multiple loop geometries which we\npropose first time, to the best of our concern, considering a magnetic quantum\nsystem. The key aspect of our work is the development of a suitable theory for\ndefining and analyzing circular spin current in presence of environmental\ndephasing and impurities. Unlike transport current in a conducting junction,\ncircular current may enhance significantly in presence of disorder and phase\nrandomizing processes. Our analysis provides a new spin dependent phenomenon,\nand can give important signatures in designing suitable spintronic devices as\nwell as selective spin regulations."
    },
    {
        "anchor": "Nonlinear Hall effect from long-lived valley-polarizing relaxons: The nonlinear Hall effect has attracted much attention due to the famous,\nwidely adopted interpretation in terms of the Berry curvature dipole in\nmomentum space. Using ab initio Boltzmann transport equations, we find a 60%\nenhancement in the nonlinear Hall effect of p-doped GeTe and its noticeable\nfrequency dependence, qualitatively different from the predictions based on the\nBerry curvature dipole. The origin of these differences is long-lived valley\npolarization in the electron distribution arising from electron-phonon\nscattering. Our findings await immediate experimental confirmation.",
        "positive": "Spin texture motion in antiferromagnetic and ferromagnetic nanowires: We propose a Hamiltonian dynamics formalism for the current and magnetic\nfield driven dynamics of ferromagnetic and antiferromagnetic domain walls in\none dimensional systems. To demonstrate the power of this formalism, we derive\nHamilton equations of motion via Poisson brackets based on the\nLandau-Lifshitz-Gilbert phenomenology, and add dissipative dynamics via the\nevolution of the energy. We use this approach to study current induced domain\nwall motion and compute the drift velocity. For the antiferromagnetic case, we\nshow that a nonzero magnetic moment is induced in the domain wall, which\nindicates that an additional application of a magnetic field would influence\nthe antiferromagnetic domain-wall dynamics. We consider both cases of the\nmagnetic field being parallel and transverse to the N{\\'e}el field. Based on\nthis formalism, we predict an orientation switch mechanism for\nantiferromagnetic domain walls which can be tested with the recently discovered\nN{\\'e}el spin orbit torques."
    },
    {
        "anchor": "Control of surface induced phase separation in immiscible semiconductor\n  alloy core-shell nanowires: Semiconductor nanowires have been shown to exhibit novel optoelectronic\nproperties with respect to bulk specimens made of the same material. However,\nif a semiconductor alloy has a miscibility gap in its phase diagram, at\nequilibrium it will phase separate, leading to deterioration of the\naforementioned properties. One way to prevent this separation is to grow the\nmaterial at low temperatures and therefore to suppress kinetics. Such growth\noften needs to be followed by high-temperature annealing in order to rid the\nsystem of undesirable growth-induced defects. In this study, we propose a\nmethod to control phase separation in core-shell nanowires during high\ntemperature annealing by tailoring geometry and strain. Using a phase field\nmodel we determined that phase separation in nanowires begins at the free\nsurface and propagates into the bulk. We discovered that including a thin shell\naround the core delays the phase separation whereas a thick shell suppresses\nthe separation almost entirely.",
        "positive": "Connectivity dependence of Fano resonances in single molecules: Using a first principles approach combined with analysis of heuristic\ntight-binding models, we examine the connectivity dependence of two forms of\nquantum interference in single molecules. Based on general arguments, Fano\nresonances are shown to be insensitive to connectivity, while Mach-Zehnder-type\ninterference features are shown to be connectivity dependent. This behaviour is\nfound to occur in molecular wires containing anthraquinone units, in which the\npendant carbonyl groups create Fano resonances, which coexist with\nmultiple-path quantum interference features."
    },
    {
        "anchor": "Tail States below the Thouless Gap in SNS junctions: Classical\n  Fluctuations: We study the tails of the density of states (DOS) in a diffusive\nsuperconductor-normal metal-superconductor (SNS) junction below the Thouless\ngap. We show that long-wave fluctuations of the concentration of impurities in\nthe normal layer lead to the formation of subgap quasiparticle states, and\ncalculate the associated subgap DOS in all effective dimensionalities. We\ncompare the resulting tails with those arising from mesoscopic gap\nfluctuations, and determine the dimensionless parameters controlling which\ncontribution dominates the subgap DOS. We observe that the two contributions\nare formally related to each other by a dimensional reduction.",
        "positive": "Superlubricity of Graphene Nanoribbons on Gold Surfaces: The state of vanishing friction known as superlubricity has important\napplications for energy saving and increasing the lifetime of devices.\nSuperlubricity detected with atomic force microscopy appears in examples like\nsliding large graphite flakes or gold nanoclusters across surfaces. However,\nthe origin of the behavior is poorly understood due to the lack of a\ncontrollable nano-contact. We demonstrate graphene nanoribbons superlubricity\nwhen sliding on gold with a joint experimental and computational approach. The\natomically well-defined contact allows us to trace the origin of\nsuperlubricity, unravelling the role played by edges, surface reconstruction\nand ribbon elasticity. Our results pave the way to the scale-up of\nsuperlubricity toward the realization of frictionless coatings."
    },
    {
        "anchor": "Spin Transfer Torque as a Non-Conservative Pseudo-Field: In this paper we show that the spin transfer torque can be described by a\npseudo magnetic field, proportional to the magnetic moment of the itinerant\nelectrons that enters the Landau-Lifshitz-Gilbert equation in the same way as\nother external or internal magnetic fields. However, unlike an ordinary\nmagnetic field, which is always conservative in nature, the spin torque induced\npseudo field may have both conservative and non-conservative components. We\nfurther show that the magnetic moment of itinerant electrons develops an\nout-of-plane component only at non-equilibrium and this component is\nresponsible for the Slonczewski type switching that acts against the damping\nand is always non-conservative. On the other hand, the in-plane components of\nthe pseudo field exist both at equilibrium and out-of-equilibrium, and are\nresponsible for the field like term. For tunnel based devices, this term\nresults in lower switching current for anti-parallel (AP) to parallel (P)\nswitching compared to P to AP, even when the torque magnitudes are completely\nsymmetric with voltage.",
        "positive": "Theory of the random potential and conductivity at the surface of a\n  topological insulator: We study the disorder potential induced by random Coulomb impurities at the\nsurface of a topological insulator (TI). We use a simple model in which\npositive and negative impurities are distributed uniformly throughout the bulk\nof the TI, and we derive the magnitude of the disorder potential at the TI\nsurface using a self-consistent theory based on the Thomas-Fermi approximation\nfor screening by the Dirac mode. Simple formulas are presented for the mean\nsquared potential both at the Dirac point and far from it, as well as for the\ncharacteristic size of electron/hole puddles at the Dirac point and the total\nconcentration of electrons/holes that they contain. We also derive an\nexpression for the autocorrelation function for the potential at the surface\nand show that it has an unusually slow decay, which can be used to verify the\nbulk origin of disorder. The implications of our model for the electron\nconductivity of the surface are also presented."
    },
    {
        "anchor": "Nonlinear spectroscopy of exciton-polaritons in a GaAs-based microcavity: We present a systematic investigation of two-photon excitation processes in a\nGaAs-based microcavity in the strong-coupling regime. We observe second\nharmonic generation resonant to the upper and lower polariton level, which\nexhibits a strong dependence on the photonic fraction of the corresponding\npolariton. In addition we have performed two-photon excitation spectroscopy to\nidentify $2p$ exciton states which are crucial for the operation as a terahertz\nlasing device, which was suggested recently [A. V. Kavokin et al., Phys. Rev.\nLett. \\textbf{108}, 197401 (2012)]. However, no distinct signatures of a $2p$\nexciton state could be identified, which indicates a low two-photon pumping\nefficiency.",
        "positive": "Limit to 2D mobility in modulation-doped GaAs quantum structures: How to\n  achieve a mobility of 100 millions: Considering scattering by unintentional background charged impurities and by\ncharged dopants in the modulation doping layer as well as by GaAs acoustic\nphonons, we theoretically consider the practical intrinsic (phonons) and\nextrinsic (background and dopants) limits to carrier mobility in modulation\ndoped AlGaAs-GaAs 2D semiconductor structures. We find that reducing background\nimpurity density to $10^{12}$ cm$^{-3}$ along with a modulation doping\nseparation of 1000 \\AA or above will achieve a mobility of $100 \\times 10^6$\ncm$^2$/Vs at a carrier density of $3\\times 10^{11}$ cm$^{-2}$ for T=1K. At T=4\n(10)K, however, the hard limit to the 2D mobility would be set by acoustic\nphonon scattering with the maximum intrinsic mobility being no higher than 22\n$(5) \\times 10^6$ cm$^2$/Vs. Detailed numerical results are presented as a\nfunction of carrier density, modulation doping distance, and temperature to\nprovide a quantitative guide to experimental efforts for achieving ultra-high\n2D mobilities."
    },
    {
        "anchor": "Interplay of non-Hermitian skin effects and Anderson localization in\n  non-reciprocal quasiperiodic lattices: Non-Hermiticity from non-reciprocal hoppings has been shown recently to\ndemonstrate the non-Hermitian skin effect (NHSE) under open boundary conditions\n(OBCs). Here we study the interplay of this effect and the Anderson\nlocalization in a \\textit{non-reciprocal} quasiperiodic lattice, dubbed\nnon-reciprocal Aubry-Andr\\'{e} model, and a \\textit{rescaled} transition point\nis exactly proved. The non-reciprocity can induce not only the NHSE, but also\nthe asymmetry in localized states with two Lyapunov exponents for both sides.\nMeanwhile, this transition is also topological, characterized by a winding\nnumber associated with the complex eigenenergies under periodic boundary\nconditions (PBCs), establishing a \\textit{bulk-bulk} correspondence. This\ninterplay can be realized by an elaborately designed electronic circuit with\nonly linear passive RLC devices instead of elusive non-reciprocal ones, where\nthe transport of a continuous wave undergoes a transition between insulating\nand amplifying. This initiative scheme can be immediately applied in\nexperiments to other non-reciprocal models, and will definitely inspires the\nstudy of interplay of NHSEs and more other quantum/topological phenomena.",
        "positive": "Quantum Dynamics of Molecular Nanomagnets in a Resonant Cavity and the\n  Maser Effect: We study the dynamics of molecular nanomagnets through a fully quantum\nmechanical model describing high-spin and high-anisotropy magnetic molecules\nsubjected to a time-dependent magnetic field along the quantization axis, which\ncontinuously inverts the population of spin states. Crystals of molecular\nnanomagnets placed inside a resonant cavity interact with a quantized\nelectromagnetic field. Relaxation of excited states takes place by means of\nspin-photon interaction, allowing stimulated emission of radiation and creating\na maser effect."
    },
    {
        "anchor": "Universal dependence on the channel conductivity of the competing weak\n  localization and antilocalization in amorphous InGaZnO$_4$ thin-film\n  transistors: We investigate the gate-voltage dependence of the magnetoconductivity of\nseveral amorphous InGaZnO$_4$ (a-IGZO) thin-film transistors (TFTs). The\nmagnetoconductivity exhibits gate-voltage- controlled competitions between weak\nlocalization (WL) and weak antilocalization (WAL), and the respective weights\nof WL and WAL contributions demonstrate an intriguing universal dependence on\nthe channel conductivity regardless of the difference in the electrical\ncharacteristics of the a-IGZO TFTs. Our findings help build a theoretical\ninterpretation of the competing WL and WAL observed in the electron systems in\na-IGZO TFTs.",
        "positive": "Spin half-adder: A new proposal is given to design a spin half-adder in a nano-junction. It is\nwell known that at finite voltage a net circulating current (known as circular\ncurrent) appears within a mesoscopic ring under asymmetric ring-to-electrode\ninterface configuration. This circular current induces a finite magnetic field\nat the center of the ring. We utilize this phenomenon to construct a spin half\nadder. The circular current induced magnetic field is used to regulate the\nalignments of local free spins, by their orientations we specify the output\nstates of the `sum' and `carry'. All the outputs are spin based, therefore the\nresults get atomically stored in the system. We also illustrate the\nexperimental possibilities of our proposed model."
    },
    {
        "anchor": "Fr\u00f6hlich Polarons from 0D to 3D: Concepts and Recent Developments: I analyse our present understanding of the Froehlich polaron with emphasis on\nthe response properties, in particular optical absorption.",
        "positive": "Spin splitting and switching effect in a four-terminal two-dimensional\n  electron gas nanostructure: We have studied the spin-splitting effect in a four-terminal two-dimensional\n(2D) electron gas system with two potential barriers generated by two surface\nmetal gates and an external perpendicular magnetic field. The calculations show\nthat by tuning the voltage applied on the gates, the injected spin-unpolarized\ncurrent can be split into different spin currents with a high efficiency. The\nsplit currents flow out of the geometry from different output leads separately.\nThe spin freedom of the outputs can be controlled by simply tuning voltage on\ngates. This phenomenon is a result of the combination of three effects - the\npotential barriers, Zeeman splitting and edge current. Furthermore, by tuning\nthe voltage on gates, the outflow spin of current in one terminal can be\nswitched. Therefore, these features open up a possibility for making a spin\nfilter or a switcher device by applying the four-terminal 2D electron gas\nsystem."
    },
    {
        "anchor": "Proposal of a one-dimensional electron gas in the steps at the\n  LaAlO$_3$-SrTiO$_3$ interface: The two-dimensional electron gas (2DEG) at the interface between LaAlO$_3$\n(LAO) and SrTiO$_3$ (STO) has become one of the most fascinating and\nhighly-debated oxide systems of recent times. Here we propose that a\none-dimensional electron gas (1DEG) can be engineered at the step edges of the\nLAO/STO interface. These predictions are supported by first principles\ncalculations and electrostatic modeling which elucidate the origin of the 1DEG\nas an electronic reconstruction to compensate a net surface charge in the step\nedge. The results suggest a novel route to increasing the functional density in\nthese electronic interfaces.",
        "positive": "Kondo effect in coupled quantum dots with RKKY interaction: Finite\n  temperature and magnetic field effects: We study transport through two quantum dots coupled by an RKKY interaction as\na function of temperature and magnetic field. By applying the Numerical\nRenormalization Group (NRG) method we obtain the transmission and the linear\nconductance. At zero temperature and magnetic field, we observe a quantum phase\ntransition between the Kondo screened state and a local spin singlet as the\nRKKY interaction is tuned. Above the critical RKKY coupling the Kondo peak is\nsplit. However, we find that both finite temperature and magnetic field restore\nthe Kondo resonance. Our results agree well with recent transport experiments\non gold grain quantum dots in the presence of magnetic impurities."
    },
    {
        "anchor": "Fundamental bound on topological gap: We provide a universal tight bound on the energy gap of topological\ninsulators by exploring relationships between topology, quantum geometry, and\noptical absorption. Applications of our theory to infrared absorption near\ntopological band inversion, magnetic circular dichorism in Chern insulators,\nand topological gap in moir\\'e materials are demonstrated.",
        "positive": "The effect of the stagnant layer on the photon mean-free-path length in\n  concentrated suspensions of nanoparticles: We analyze the possibility of evaluation of the thickness and refractive\nindex of the stagnant layer in concentrated suspensions of nanoparticles\nthrough the transport characteristics of scattered light photons. The analysis\nis based on a physically-transparent generalization of the concept of the\nsingle scattering intensity off systems in which the number of particles within\nregions with linear sizes of order of the wavelength in the medium greatly\nexceeds unity. This generalization is carried out within the notion of compact\ngroups of particles, makes it possible to go beyond the traditional Born\napproximation, and take into account many-particle effects contributed from\nthose ranges of integration variables in the terms of the iteration series for\nthe scattered field where the internal propagators have delta-function-type\nbehavior. The evaluation of the photon transport characteristics becomes\npossible without a detailed modeling of many-particle scattering and\ncorrelation processes in the system. The photon mean-free-path length, $l$, is\ninvestigated as a function of the stagnant refractive index and that of the\nlayer thickness to show a noticeable effect of both parameters on it. As the\nlayer refractive index is increased at a fixed layer thickness, $l$ decreases\nbecause the suspension optical density increases. As a function of the layer\nthickness, $l$ reveals different types of behavior, depending on the relation\nbetween refractive indices of the stagnant layer and base liquid. If the former\nis smaller than the latter, this behavior is increasing; in the opposite case,\nit is decreasing. An experimentally observed increase of $l$ with the particle\nconcentration is explained as a manifestation of higher correlation effects.\nOur theory reveals that the stagnant layer make the situation more complicated,\nfor both factors may either enhance or diminish each other."
    },
    {
        "anchor": "Controlled Finite Momentum Pairing and Spatially Varying Order Parameter\n  in Proximitized HgTe Quantum Wells: Conventional $s$-wave superconductivity is understood to arise from singlet\npairing of electrons with opposite Fermi momenta, forming Cooper pairs whose\nnet momentum is zero [1]. Several recent studies have focused on structures\nwhere such conventional $s$-wave superconductors are coupled to systems with an\nunusual configuration of electronic spin and momentum at the Fermi surface.\nUnder these conditions, the nature of the paired state can be modified and the\nsystem may even undergo a topological phase transition [2, 3]. Here we present\nmeasurements and theoretical calculations of several HgTe quantum wells coupled\nto either aluminum or niobium superconductors and subject to a magnetic field\nin the plane of the quantum well. By studying the oscillatory response of\nJosephson interference to the magnitude of the in-plane magnetic field, we find\nthat the induced pairing within the quantum well is spatially varying. Cooper\npairs acquire a tunable momentum that grows with magnetic field strength,\ndirectly reflecting the response of the spin-dependent Fermi surfaces to the\nin-plane magnetic field. In addition, in the regime of high electron density,\nnodes in the induced superconductivity evolve with the electron density in\nagreement with our model based on the Hamiltonian of Bernevig, Hughes, and\nZhang [4]. This agreement allows us to quantitatively extract the value of\n$\\tilde{g}/v_{F}$, where $\\tilde{g}$ is the effective g-factor and $v_{F}$ is\nthe Fermi velocity. However, at low density our measurements do not agree with\nour model in detail. Our new understanding of the interplay between spin\nphysics and superconductivity introduces a way to spatially engineer the order\nparameter, as well as a general framework within which to investigate\nelectronic spin texture at the Fermi surface of materials.",
        "positive": "Collective effects in emission of quantum dots strongly coupled to a\n  microcavity photon: A theory of non-linear emission of quantum dot ensembles coupled to the\noptical mode of the microcavity is presented. Numerical results are compared\nwith analytical approaches. The effects of exciton-exciton interaction within\nthe quantum dots and with the reservoir formed by nonresonant pumping are\nconsidered. It is demonstrated, that the nonlinearity due to the interaction\nstrongly affects the shape of the emission spectra. The collective superradiant\nmode of the excitons is shown to be stable against the non-linear effects."
    },
    {
        "anchor": "Topological phases in the periodically kicked Chern insulators: Novel topological properties that arose in the periodically driven system are\nunique, in which there are two kinds of quasienergy gaps, the zero quasienergy\ngap and the $\\pi$ quasienergy gap. The corresponding edge modes would traverse\neither the zero quasienergy gap or the $\\pi$ quasienergy gap, or traverse both\ntwo quasienergy gaps. And the characterization of these two kinds of edge modes\nmight not be the same. However, in this paper, we find that both the zero edge\nmodes and the $\\pi$ edge modes in the Floquet Chern insulators can be\ncharacterized by the same topological invariant, where the corresponding Dirac\nmass term is periodically kicked. Particularly, we take the periodically kicked\nQi-Wu-Zhang model as an illustrative example. In this model, the topology is\ncharacterized by the Floquet Chern number $C_F$, and there are six different\ntopological phases in total, denoted as $C_F=\\{-1_0,-2,-1_\\pi,1_\\pi,2,1_0\\}$.\nFurthermore, we find that the Floquet operator associated with the periodically\nkicked Qi-Wu-Zhang model reduces to a Dirac Hamiltonian in the low-energy\nlimit. Then, the phase diagram is uncovered by examining the topology of this\nDirac Hamiltonian. Additionally, we explore the orders of topological phase\ntransitions in the context of Floquet stationary states by analyzing the von\nNeumann entropy of these states. Our work provides further insights into the\ntopological phases in periodically driven systems.",
        "positive": "Tunneling of multi-Weyl semimetals through a potential barrier under the\n  influence of magnetic fields: We investigate the tunneling of the quasiparticles arising in multi-Weyl\nsemimetals through a barrier consisting of both electrostatic and vector\npotentials, existing uniformly in a finite region along the transmission axis.\nThe dispersion of a multi-Weyl semimetal is linear in one direction (say,\n$k_z$), and proportional to $k_\\perp^J$ in the plane perpendicular to it (where\n$k_\\perp =\\sqrt{k_x^2+k_y^2}$). Hence, we study the cases when the barrier is\nperpendicular to $k_z$ and $k_x$, respectively. For comparison, we also state\nthe corresponding results for the Weyl semimetal."
    },
    {
        "anchor": "Quantum coherent biomolecular energy transfer with spatially correlated\n  fluctuations: We show that the quantum coherent transfer of excitations between\nbiomolecular chromophores is strongly influenced by spatial correlations of the\nenvironmental fluctuations. The latter are due either to propagating\nenvironmental modes or to local fluctuations with a finite localization length.\nA simple toy model of a single donor-acceptor pair with spatially separated\nchromophore sites allows to investigate the influence of these spatial\ncorrelations on the quantum coherent excitation transfer. The sound velocity of\nthe solvent determines the wave lengths of the environmental modes, which, in\nturn, has to be compared to the spatial distance of the chromophore sites. When\nthe wave length exceeds the distance between donor and acceptor site, we find\nstrong suppression of decoherence. In addition, we consider two spatially\nseparated donor-acceptor pairs under the influence of propagating environmental\nmodes. Depending on their wave lengths fixed by the sound velocity of the\nsolvent material, the spatial range of correlations may extend over typical\ninterpair distances, which can lead to an increase of the decohering influence\nof the solvent. Surprisingly, this effect is counteracted by increasing\ntemperature.",
        "positive": "Effects of nuclear spins on the transport properties of the edge of\n  two-dimensional topological insulators: The electrons in the edge channels of two-dimensional topological insulators\ncan be described as a helical Tomonaga-Luttinger liquid. They couple to nuclear\nspins embedded in the host materials through the hyperfine interaction, and are\ntherefore subject to elastic spin-flip backscattering on the nuclear spins. We\ninvestigate the nuclear-spin-induced edge resistance due to such backscattering\nby performing a renormalization-group analysis. Remarkably, the effect of this\nbackscattering mechanism is stronger in a helical edge than in nonhelical\nchannels, which are believed to be present in the trivial regime of InAs/GaSb\nquantum wells. In a system with sufficiently long edges, the disordered nuclear\nspins lead to an edge resistance which grows exponentially upon lowering the\ntemperature. On the other hand, electrons from the edge states mediate an\nanisotropic Ruderman-Kittel-Kasuya-Yosida nuclear spin-spin interaction, which\ninduces a spiral nuclear spin order below the transition temperature. We\ndiscuss the features of the spiral order, as well as its experimental\nsignatures. In the ordered phase, we identify two backscattering mechanisms,\ndue to charge impurities and magnons. The backscattering on charge impurities\nis allowed by the internally generated magnetic field, and leads to an\nAnderson-type localization of the edge states. The magnon-mediated\nbackscattering results in a power-law resistance, which is suppressed at zero\ntemperature. Overall, we find that in a sufficiently long edge the nuclear\nspins, whether ordered or not, suppress the edge conductance to zero as the\ntemperature approaches zero."
    },
    {
        "anchor": "The Stochastic Dynamics of an Array of Atomic Force Microscopes in a\n  Viscous Fluid: We consider the stochastic dynamics of an array of two closely spaced atomic\nforce microscope cantilevers in a viscous fluid for use as a possible\nbiomolecule sensor. The cantilevers are not driven externally, as is common in\napplications of atomic force microscopy, and we explore the stochastic\ncantilever dynamics due to the constant buffeting of fluid particles by\nBrownian motion. The stochastic dynamics of two adjacent cantilevers are\ncorrelated due to long range effects of the viscous fluid. Using a recently\nproposed thermodynamic approach the hydrodynamic correlations are quantified\nfor precise experimental conditions through deterministic numerical\nsimulations. Results are presented for an array of two readily available atomic\nforce microscope cantilevers. It is shown that the force on a cantilever due to\nthe fluid correlations with an adjacent cantilever is more than 3 times smaller\nthan the Brownian force on an individual cantilever. Our results indicate that\nmeasurements of the correlations in the displacement of an array of atomic\nforce microscopes can detect piconewton forces with microsecond time\nresolution.",
        "positive": "Transient regime in non-linear transport through many-level quantum dots: We investigate the nonstationary electronic transport in noninteracting\nnanostructures driven by a finite bias and time-dependent signals applied at\ntheir contacts to the leads. The systems are modelled by a tight-binding\nHamiltonian and the transient currents are computed from the non-equilibrium\nGreen-Keldysh formalism. The numerical implementation is not restricted to weak\ncoupling to the leads and does not imply the wide-band limit assumption for the\nspectral width of the leads. As an application of the method we study in detail\nthe transient behavior and the charge dynamics in single and double quantum\ndots connected to leads by a step-like potential, but the method allows as well\nthe consideration of non-periodic potentials or short pulses. We show that when\nthe higher energy levels of the isolated system are located within the bias\nwindow of the leads the transient current approaches the steady state in a\nnon-oscillatory smooth fashion. At moderate coupling to the leads and fixed\nbias the transient acquires a step-like structure, the length of the steps\nincreasing with the system size. The number of levels inside a finite bias\nwindow can be tuned by a constant gate potential. We find also that the\ntransient behavior depends on the specific way of coupling the leads to the\nmesoscopic system."
    },
    {
        "anchor": "Chiral topological phases and fractional domain wall excitations in\n  one-dimensional chains and wires: According to the general classification of topological insulators, there\nexist one-dimensional chirally (sublattice) symmetric systems that can support\nany number of topological phases. We introduce a zigzag fermion chain with\nspin-orbit coupling in magnetic field and identify three distinct topological\nphases. Zero-mode excitations, localized at the phase boundaries, are\nfractionalized: two of the phase boundaries support $\\pm e/2$ charge states\nwhile one of the boundaries support $\\pm e$ and neutral excitations. In\naddition, a finite chain exhibits $\\pm e/2$ edge states for two of the three\nphases. We explain how the studied system generalizes the Peierls-distorted\npolyacetylene model and discuss possible realizations in atomic chains and\nquantum spin Hall wires.",
        "positive": "The generalized plane piezoelectric problem: Theoretical formulation and\n  application to heterostructure nanowires: We present a systematic methodology for the reformulation of a broad class of\nthree-dimensional (3D) piezoelectric problems into a two-dimensional (2D)\nmathematical form. The sole underlying hypothesis is that the system geometry\nand material properties as well as the applied loads (forces and charges) and\nboundary conditions are translationally invariant along some direction. This\nclass of problems is commonly denoted here as the generalized plane\npiezoelectric (GPP) problem. The first advantage of the generalized plane\nproblems is that they are more manageable from both analytical and\ncomputational points of view. Moreover, they are flexible enough to accommodate\nany geometric cross section, crystal class symmetry, axis orientation and a\nwide range of boundary conditions. As an illustration we present numerical\nsimulation of indefinite lattice-mismatched core-shell nanowires made of\ndiamond Ge/Si and zincblende piezoelectric InN/GaN materials. The remarkable\nagreement with exact 3D simulations of finite versions of those systems reveal\nthe GPP approach as a reliable procedure to study accurately and with moderate\ncomputing resources the strain and electric field distribution in elongated\npiezoelectric systems."
    },
    {
        "anchor": "The Chern Number Governs Soliton Motion in Nonlinear Thouless Pumps: Nonlinear Thouless pumps for bosons exhibit quantized pumping via soliton\nmotion, despite the lack of a meaningful notion of filled bands. However, the\ntheoretical underpinning of this quantization, as well as its relationship to\nthe Chern number, has thus far been lacking. Here we show that for low power\nsolitons, transport is dictated by the Chern number of the band from which the\nsoliton bifurcates. We do this by expanding the discrete nonlinear\nSchr\\\"odinger equation (equivalently, the Gross-Pitaevskii equation) in the\nbasis of Wannier states, showing that the soliton's position is dictated by\nthat of the Wannier state throughout the pump cycle. Furthermore, we describe\nsoliton pumping in two dimensions.",
        "positive": "Light-induced chiral gauge field in a massive 3D Dirac electron system: The concept of the chiral gauge field (CGF), originally developed in\ntheoretical particle physics, has now emerged in condensed matter systems in\nmaterials known as Weyl semimetals. In general, Weyl semimetals emerge from\nDirac semimetals when time-reversal or spatial-inversion symmetries are broken.\nRecently, it has gained a growing interest to manipulate such topological\nstates of matter by implementing the CGF by shining light to materials. Here we\nhave demonstrated the emergence of CGF in a massive 3D Dirac electron system in\nthe paramagnetic phase of Co3Sn2S2, which exhibits a ferromagnetic Weyl\nsemimetal phase at low temperatures. We first show theoretically that the\nillumination of circularly polarized light implements the CGF in the\nparamagnetic state of Co3Sn2S2 and gives rise to a topological Weyl state,\nwhich can be realized only in the nonequilibrium state. Then we demonstrated\nthat the presence of light-induced CGF through the observation of light-induced\nanomalous Hall effect, the behavior of which quantitatively agrees with the\ncalculation from the Floquet theory. The light-induced AHE manifests the Berry\ncurvature which becomes nonzero as the bands split due to the light-induced\nCGF. Our demonstration paves a new pathway for ultrafast manipulation of\ntopological phases in 3D Dirac semimetals and for further exploring new quantum\nmatter phases which can be only achieved by light."
    },
    {
        "anchor": "Direct probing of band-structure Berry phase in diluted magnetic\n  semiconductors: We report on experimental evidence of the Berry phase accumulated by the\ncharge carrier wave function in single-domain nanowires made from a\n(Ga,Mn)(As,P) diluted ferromagnetic semiconductor layer. Its signature on the\nmesoscopic transport measurements is revealed as unusual patterns in the\nmagnetoconductance, that are clearly distinguished from the universal\nconductance fluctuations. We show that these patterns appear in a magnetic\nfield region where the magnetization rotates coherently and are related to a\nchange in the band-structure Berry phase as the magnetization direction\nchanges. They should be thus considered as a band structure Berry phase\nfingerprint of the effective magnetic monopoles in the momentum space. We argue\nthat this is an efficient method to vary the band structure in a controlled way\nand to probe it directly. Hence, (Ga,Mn)As appears to be a very interesting\ntest bench for new concepts based on this geometrical phase.",
        "positive": "Semiclassical theory of the photogalvanic effect in non-centrosymmetric\n  systems: We develop a semiclassical theory of nonlinear transport and the\nphotogalvanic effect in non-centrosymmetric media. We show that terms in\nsemiclassical kinetic equations for electron motion which are associated with\nthe Berry curvature and side jumps give rise to a dc current quadratic in the\namplitude of the ac electric field. We demonstrate that the circular\nphotogalvanic effect is governed by these terms in contrast to the linear\nphotogalvanic effect and nonlinear I-V characteristics which are governed\nmainly by the skew scattering mechanism. In addition, the Berry curvature\ncontribution to the magnetic-field induced photogalvanic effect is calculated."
    },
    {
        "anchor": "Strain-induced modulation of Dirac cones and van Hove singularities in\n  twisted graphene bilayer: By means of atomistic tight-binding calculations, we investigate the effects\nof uniaxial strain on the electronic bandstructure of twisted graphene bilayer.\nWe find that the bandstructure is dramatically deformed and the degeneracy of\nthe bands is broken by strain. As a conseqence, the number of Dirac cones can\ndouble and the van Hove singularity points are separated in energy. The\ndependence of these effects on the strength of strain, its applied direction\nand the twist angle is carefully clarified. As an important result, we\ndemonstrate that the position of van Hove singularities can be modulated by\nstrain, suggesting the possibility of observing this phenomenon at low energy\nin a large range of twist angle (i.e., larger than $10^\\circ$). Unfortunately,\nthese interesting/important phenomena have not been clarified in the previous\nworks based on the continuum approximation. While they are in good agreement\nwith available experiments, our results provide a detailed understanding of the\nstrain effects on the electronic properties and may motivate other\ninvestigations of electronic transport in this type of graphene lattice.",
        "positive": "Coherent and dissipative coupling in a magneto-mechanical system: Hybrid elastic and spin waves hold promises for energy-efficient and\nversatile generation and detection of magnetic signals, with potentially long\ncoherence times. Here we report on the combined elastic and magnetic dynamics\nin a one-dimensional magneto-mechanical crystal composed of an array of\nmagnetic nanowires. Phononic and magnonic modes are impulsively excited by an\noptical ultrafast trigger and their decay is monitored by time resolved Magneto\nOptical Kerr Effect, with complementary Brillouin Light Scattering measurements\nand micromagnetic simulations. The strength and degree of mixing of coherent\nand dissipative coupling of the quasi-particles is determined quantitatively."
    },
    {
        "anchor": "Casimir Force in Non-Planar Geometric Configurations: The Casimir force for charge-neutral, perfect conductors of non-planar\ngeometric configurations have been investigated. The configurations are: (1)\nthe plate-hemisphere, (2) the hemisphere-hemisphere and (3) the spherical\nshell. The resulting Casimir forces for these physical arrangements have been\nfound to be attractive. The repulsive Casimir force found by Boyer for a\nspherical shell is a special case requiring stringent material property of the\nsphere, as well as the specific boundary conditions for the wave modes inside\nand outside of the sphere. The necessary criteria in detecting Boyer's\nrepulsive Casimir force for a sphere are discussed at the end of this thesis.",
        "positive": "Scanning Gate Microscopy of Quantum Contacts Under Parallel Magnetic\n  Field: Beating Patterns Between Spin-Split Transmission Peaks or Channel\n  Openings: We study the conductance $g$ of an electron interferometer created in a two\ndimensional electron gas between a nanostructured contact and the depletion\nregion induced by the charged tip of a scanning gate microscope. Using\nnon-interacting models, we study the beating pattern of interference fringes\nexhibited by the images giving $g$ as a function of the tip position when a\nparallel magnetic field is applied. The analytical solution of a simplified\nmodel allows us to distinguish between two cases: (i) If the field is applied\neverywhere, the beating of Fabry-P\\'erot oscillations of opposite spins gives\nrise to interference rings which can be observed at low temperatures when the\ncontact is open between spin-split transmission resonances. (ii) If the field\nacts only upon the contact, the interference rings cannot be observed at low\ntemperatures, but only at temperatures of the order of the Zeeman energy. For a\ncontact made of two sites in series, a model often used for describing an\ninversion-symmetric double-dot setup, a pseudo-spin degeneracy is broken by the\ninter-dot coupling and a similar beating effect can be observed without\nmagnetic field at temperatures of the order of the interdot coupling.\nEventually, numerical studies of a quantum point contact with quantized\nconductance plateaus confirm that a parallel magnetic field applied everywhere\nor only upon the contact gives rises to similar beating effects between\nspin-split channel openings."
    },
    {
        "anchor": "Wurtzite spin lasers: Semiconductor lasers are strongly altered by adding spin-polarized carriers.\nSuch spin lasers could overcome many limitations of their conventional\n(spin-unpolarized) counterparts. While the vast majority of experiments in spin\nlasers employed zinc-blende semiconductors, the room temperature electrical\nmanipulation was first demonstrated in wurtzite GaN-based lasers. However, the\nunderlying theoretical description of wurtzite spin lasers is still missing. To\naddress this situation, focusing on (In,Ga)N-based wurtzite quantum wells, we\ndevelop a theoretical framework in which the calculated microscopic\nspin-dependent gain is combined with a simple rate equation model. A small\nspin-orbit coupling in these wurtzites supports simultaneous spin polarizations\nof electrons and holes, providing unexplored opportunities to control spin\nlasers. For example, the gain asymmetry, as one of the key figures of merit\nrelated to spin amplification, can change the sign by simply increasing the\ncarrier density. The lasing threshold reduction has a nonmonotonic depenedence\non electron spin polarization, even for a nonvanishing hole spin polarization.",
        "positive": "Floquet theory of microwave absorption by an impurity in two dimensional\n  electron gas: We investigate the dynamics of a two-dimensional electron gas (2DEG) under\ncircular polarized microwave radiation in presence of dilute localized\nimpurities. Inspired by recent developments on Floquet topological insulators\nwe obtain the Floquet wavefunctions of this system which allow us to predict\nthe microwave absorption and charge density responses of the electron gas, we\ndemonstrate how these properties can be understood from the underlying\nsemiclassical dynamics even for impurities with a size of around a magnetic\nlength. The charge density response takes the form of a rotating charge density\nvortex around the impurity that can lead to a significant renormalization of\nthe external microwave field which becomes strongly inhomogeneous on the scale\nof a cyclotron radius around the impurity. We show that this in-homogeneity can\nsuppress the circular polarization dependence which is theoretically expected\nfor MIRO but which was not observed in MIRO experiments on semiconducting\n2DEGs. Our explanation, for this so far unexplained polarization independence,\nhas close similarities with the Azbel'-Kaner effect in metals where the\ninteraction length between the microwave field and conduction electrons is much\nsmaller than the cyclotron radius due to skin effect generating harmonics of\nthe cyclotron resonance."
    },
    {
        "anchor": "Can spintronic field effect transistors compete with their electronic\n  counterparts?: Current interest in spintronics is largely motivated by a belief that spin\nbased devices (e.g. spin field effect transistors) will be faster and consume\nless power than their electronic counterparts. Here we show that this is\ngenerally untrue. Unless materials with extremely strong spin orbit interaction\ncan be developed, the spintronic devices will not measure up to their\nelectronic cousins. We also show that some recently proposed modifications of\nthe original spin field effect transistor concept of Datta and Das [Appl. Phys.\nLett., Vol. 56, 665 (1990)] actually lead to worse performance than the\noriginal construct.",
        "positive": "Numerical package for QFT calculations of defect-induced phenomena in\n  graphene: We introduce a computationally efficient method based on the path integral\nformalism to describe defect-modified graphene. By taking into account the\nentire Brillouin zone, our approach respects the lattice symmetry and can be\nused to investigate both short-range and long-range effects. The proposed\nmethod's key advantage is that the computational complexity does not increase\nwith the system size, scaling, instead, with the number of defects. As a\ndemonstration of our method, we explore the graphene-mediated RKKY interaction\nbetween multiple magnetic impurities. Our results concur with earlier findings\nby showing that the interaction strength and sign depend on various factors\nlike impurity separation, sublattice arrangement, and system doping. We\ndemonstrate that frustration can be introduced between the impurity spins by\ncontrolling their relative positions and that this frustration can be switched\non and off by tuning the chemical potential of the system."
    },
    {
        "anchor": "Fragile topological insulators protected by rotation symmetry without\n  spin-orbit coupling: We present a series of models of three-dimensional rotation-symmetric fragile\ntopological insulators in class AI (time-reversal symmetric and spin-orbit-free\nsystems), which have gapless surface states protected by time-reversal ($T$)\nand $n$-fold rotation ($C_n$) symmetries ($n=2,4,6$). Our models are\ngeneralizations of Fu's model of a spinless topological crystalline insulator,\nin which orbital degrees of freedom play the role of pseudo-spins. We consider\nminimal surface Hamiltonian with $C_n$ symmetry in class AI and discuss\npossible symmetry-protected gapless surface states, i.e., a quadratic band\ntouching and multiple Dirac cones with linear dispersion. We characterize\ntopological structure of bulk wave functions in terms of two kinds of\ntopological invariants obtained from Wilson loops: $\\mathbb{Z}_2$ invariants\nprotected by $C_n$ ($n=4,6$) and time-reversal symmetries, and\n$C_2T$-symmetry-protected $\\mathbb{Z}$ invariants (the Euler class) when the\nnumber of occupied bands is two. Accordingly, our models realize two kinds of\nfragile topological insulators. One is a fragile $\\mathbb{Z}$ topological\ninsulator whose only nontrivial topological index is the Euler class that\nspecifies the number of surface Dirac cones. The other is a fragile\n$\\mathbb{Z}_2$ topological insulator having gapless surface states with either\na quadratic band touching or four (six) Dirac cones, which are protected by\ntime-reversal and $C_4$ ($C_6$) symmetries. Finally, we discuss the instability\nof gapless surface states against the addition of $s$-orbital bands and\ndemonstrate that surface states are gapped out through hybridization with\nsurface-localized $s$-orbital bands.",
        "positive": "Field emitter electrostatics: a review with special emphasis on modern\n  high-precision finite-element modelling: This review of quantitative field emitter electrostatics, covering\nanalytical, numerical and fitted-formula approaches, is thought the first of\nits kind. The review relates chiefly to situations where emitters operate in an\nelectronically ideal manner, and zero-current electrostatics is applicable.\nTerminology is carefully described and is polarity independent; thus the review\napplies to both field electron and field ion emitters. It also applies more\ngenerally to charged, pointed electron-conductors that exhibit the\n\"electrostatic lightning-rod effect\", but are poorly discussed in general\nelectricity and magnetism literature. Modern electron-conductor electrostatics\nis an application of the chemical thermodynamics and statistical mechanics of\nelectrons. The review focuses chiefly on the electrostatics of two common basic\nemitter forms: the needle-shaped emitters used in traditional projection\ntechnologies; and the post-shaped emitters often used in modelling large-area\nmulti-emitter electron sources. In the post-on-plane context, we consider in\ndetail both the electrostatics of the single post and the interaction between\ntwo identical posts that occurs as a result of electrostatic depolarization\n(often called \"screening\" or \"shielding\"). Core to the review are discussions\nof the \"minimum domain dimensions\" method for implementing effective\nfinite-element-method electrostatic simulations, and of the variant that leads\nto very precise estimates of dimensionless field enhancement factors (error\ntypically less than 0.001 % in situations where analytical comparisons exist).\nBrief outline discussions, and core references, are given for each of many\n\"related considerations\" that are relevant to the electrostatic situations,\nmethods and results described. Many areas of field emitter electrostatics are\nsuggested where further research and/or separate mini-reviews would probably be\nuseful."
    },
    {
        "anchor": "Bilayer Graphene Lateral Contacts for DNA Sequencing: Translocation of DNA through a nanopore with embedded electrodes is at the\ncentre of new rapid inexpensive sequencing methods which allow distinguishing\nthe four nucleobases by their different electronic structure. However, the\nsubnanometer separation between nucleotides in DNA requires ultra-sharp probes.\nHere, we propose a device architecture consisting of a nanopore formed in\nbilayer graphene, with the two layers acting as separate electrical contacts.\nThe 0.34 nm interlayer distance of graphene is ideally suited for electrical\ncoupling to a single nucleobase, avoiding the difficulty of fabricating probes\nwith subnanometer precision. The top and bottom graphene electrodes contact the\ntarget molecule from the same lateral side, removing the orders-of-magnitude\ntunneling current variations between smaller pyrimidine bases and larger purine\nbases. We demonstrate that incorporating techniques for molecular manipulation\nenables the proposed device to sequence single-stranded DNA and that it offers\neven the prospect of sequencing double-stranded DNA.",
        "positive": "Mesoscopic Rectifiers Based on Ballistic Transport: Playing off\n  Classical against Quantum Mechanics: Recent experiments on symmetry-broken mesoscopic semiconductor structures\nhave exhibited an amazing rectifying effect in the transverse current-voltage\ncharacteristics with promising prospects for future applications. We present a\nsimple microscopic model, which takes into account the energy dependence of\ncurrent-carrying modes and explains the rectifying effect by an interplay of\nfully quantized and quasi-classical transport channels in the system. It also\nsuggests the design of a ballistic rectifier with an optimized rectifying\nsignal and predicts voltage oscillations which may provide an experimental test\nfor the mechanism considered here."
    },
    {
        "anchor": "Excitation spectra for Andreev billiards of Box and Disk geometries: We study Andreev billiards of box and disk geometries by matching the wave\nfunctions at the interface of the normal and the superconducting region using\nthe exact solutions of the Bogoliubov-de Gennes equation. The mismatch in the\nFermi wavenumbers and the effective masses of the normal system and the\nsuperconductor, as well as the tunnel barrier at the interface are taken into\naccount. A Weyl formula (for the smooth part of the counting function of the\nenergy levels) is derived. The exact quantum mechanical calculations show\nequally spaced singularities in the density of states. Based on the\nBohr-Sommerfeld quantization rule a semiclassical theory is proposed to\nunderstand these singularities. For disk geometries two kinds of states can be\ndistinguished: states either contribute through whispering gallery modes or are\nAndreev states strongly coupled to the superconductor. Controlled by two\nrelevant material parameters, three kinds of energy spectra exist in disk\ngeometry. The first is dominated by Andreev reflections, the second, by normal\nreflections in an annular disk geometry. In the third case the coherence length\nis much larger than the radius of the superconducting region, and the spectrum\nis identical to that of a full disk geometry.",
        "positive": "Transport through graphene-like flakes with intrinsic spin orbit\n  interactions: It has been shown recently [J. L. Lado et al., Phys. Rev. Lett. 113, 027203\n(2014)] that edge magnetic moments in graphene-like nanoribbons are strongly\ninfluenced by the intrinsic spin-orbit interaction. Due to this interaction an\nanisotropy comes about which makes the in-plane arrangement of magnetic moments\nenergetically more favorable than that corresponding to the out-of-plane\nconfiguration. In this paper we raise both the edge magnetism problem as well\nas differential conductance and shot noise Fano factor issues, in the context\nof finite-size flakes within the Coulomb blockade (CB) transport regime. Our\nfindings elucidate the following problems: (i) modification of the CB diamonds\nby the appearance of the in-plane magnetic moments, (ii) modification of the CB\ndiamonds by intrinsic spin-orbit interaction."
    },
    {
        "anchor": "Controlling free superflow, dark matter and luminescence rings of\n  excitons in quantum well structures: Following the discovery of Bose-Einstein condensation (BEC) in ultra cold\natoms [E. Gosta, Nobel Lectures in Physics (2001-2005), World Scientific\n(2008)], there has been a huge experimental and theoretical push to try and\nilluminate a superfluid state of Wannier-Mott excitons. Excitons in quantum\nwells, generated by a laser pulse, typically diffuse only a few micrometers\nfrom the spot they are created. However, Butov et al. and Snoke et al. reported\nluminescence from indirect and direct excitons hundreds of micrometers away\nfrom the laser excitation spot in double and single quantum well (QW)\nstructures at low temperatures. This luminescence appears as a ring around the\nlaser spot with the dark region between the spot and the ring. Developing the\ntheory of a free superflow of Bose-liquids we show that the macroscopic\nluminesce rings and the dark state are signatures of the coherent superflow of\ncondensed excitons at temperatures below their Berezinskii-Kosterlitz-Thouless\n(BKT) transition temperature. To further verify the dark excitonic superflow we\npropose several keystone experiments, including interference of superflows from\ntwo laser spots, vortex formation, scanning of moving dipole moments, and a\ngiant increase of the luminescence distance by applying one-dimensional\nconfinement potential. These experiments combined with our theory will open a\nnew avenue for creating and controlling superflow of coherent excitons on\nnanoscale.",
        "positive": "Tuning the inter-shell splitting in self-assembled CdTe quantum dots: We present photoluminescence studies of highly excited single self--assembled\nCdTe quantum dots under continuous--wave and pulsed excitations. We observe\nappearance of emission bands related to sequential filling of s--, p-- and\nd--shells. We analyze the inter-shell splitting for five samples, in which the\ndots were formed from a strained CdTe layer of different width. We find that\nwith increasing the CdTe layer width the inter-shell splitting increases. In a\ntime resolved measurement, we observe a radiative cascade between transitions\ninvolving one, two, and more than two excitons."
    },
    {
        "anchor": "Switching the sign of photon induced exchange interactions in\n  semiconductor microcavities with finite quality factors: We investigate coupling of localized spins in a semiconductor quantum dot\nembedded in a microcavity with a finite quality factor. The lowest cavity mode\nand the quantum dot exciton are coupled forming a polariton, whereas excitons\ninteract with localized spins via exchange. The finite quality of the cavity Q\nis incorporated in the model Hamiltonian by adding an imaginary part to the\nphoton frequency. The Hamiltonian, which treats photons, spins and excitons\nquantum mechanically, is solved exactly. Results for a single polariton clearly\ndemonstrate the existence of a resonance, sharper as the temperature decreases,\nthat shows up as an abrupt change between ferromagnetic and antiferromagnetic\nindirect anisotropic exchange interaction between localized spins. The origin\nof this spin-switching finite-quality-factor effect is discussed in detail\nremarking on its dependence on model parameters, i.e., light-matter coupling,\nexchange interaction between impurities, detuning and quality factor. For\nparameters corresponding to the case of a (Cd,Mn)Te quantum dot, the resonance\nshows up for Q around 70 and detuning around 10 meV. In addition, we show that,\nfor such a quantum dot, and the best cavities actually available (quality\nfactors better than 200) the exchange interaction is scarcely affected.",
        "positive": "Chiral Majorana edge states in HgTe quantum wells: HgTe-based quantum wells (QWs) recently attracted a lot of attention for the\nrealization of a two-dimensional topological insulator with protected helical\nedge states. Another class of topological systems are topological\nsuperconductors (TSCs) with Majorana edge states. In this paper, we show how\nproximity induced s-wave superconductivity in the bulk of HgTe-QWs and in the\npresence of a Zeeman field can exhibit a TSC with chiral Majorana edge states.\nWe calculate the topological invariants and the corresponding Majorana edge\nstates explicitly within a four-band model accounting for inversion symmetry\nbreaking terms due to Rashba spin-orbit coupling and bulk inversion asymmetry\npresent in these QWs."
    },
    {
        "anchor": "Quantum Effects in Small-Capacitance Single Josephson Junctions: We have measured the current-voltage (I-V) characteristics of\nsmall-capacitance single Josephson junctions at low temperatures (T=0.02-0.6\nK), where the strength of the coupling between the single junction and the\nelectromagnetic environment was controlled with one-dimensional arrays of dc\nSQUIDs. The single-junction I-V curve is sensitive to the impedance of the\nenvironment, which can be tuned IN SITU. We have observed Coulomb blockade of\nCooper-pair tunneling and even a region of negative differential resistance,\nwhen the zero-bias resistance R_0' of the SQUID arrays is much higher than the\nquantum resistance R_K = h/e^2 = 26 kohm. The negative differential resistance\nis evidence of coherent single-Cooper-pair tunneling within the theory of\ncurrent-biased single Josephson junctions. Based on the theory, we have\ncalculated the I-V curves numerically in order to compare with the experimental\nones at R_0' >> R_K. The numerical calculation agrees with the experiments\nqualitatively. We also discuss the R_0' dependence of the\nsingle-Josephson-junction I-V curve in terms of the superconductor-insulator\ntransition driven by changing the coupling to the environment.",
        "positive": "Electronics and Chemistry: Varying Single Molecule Junction Conductance\n  Using Chemical Substituents: We measure the low bias conductance of a series of substituted benzene\ndiamine molecules while breaking a gold point contact in a solution of the\nmolecules. Transport through these substituted benzenes is by means of\nnonresonant tunneling or superexchange, with the molecular junction conductance\ndepending on the alignment of the metal Fermi level to the closest molecular\nlevel. Electron-donating substituents, which drive the occupied molecular\norbitals up, increase the junction conductance, while electron-withdrawing\nsubstituents have the opposite effect. Thus for the measured series,\nconductance varies inversely with the calculated ionization potential of the\nmolecules. These results reveal that the occupied states are closest to the\ngold Fermi energy, indicating that the tunneling transport through these\nmolecules is analogous to hole tunneling through an insulating film."
    },
    {
        "anchor": "Morphing of 2D Hole Systems at $\u03bd=3/2$ in Parallel Magnetic Fields:\n  Compressible, Stripe, and Fractional Quantum Hall Phases: A transport study of two-dimensional (2D) holes confined to wide GaAs quantum\nwells provides a glimpse of a subtle competition between different many-body\nphases at Landau level filling $\\nu=3/2$ in tilted magnetic fields. At large\ntilt angles ($\\theta$), an anisotropic, stripe (or nematic) phase replaces the\nisotropic compressible Fermi sea at $\\nu=3/2$ if the quantum well has a\nsymmetric charge distribution. When the charge distribution is made asymmetric,\ninstead of the stripe phase, an even-denominator fractional quantum state\nappears at $\\nu=3/2$ in a range of large $\\theta$, and reverts back to a\ncompressible state at even higher $\\theta$. We attribute this remarkable\nevolution to the significant mixing of the excited and ground-state Landau\nlevels of 2D hole systems in tilted fields.",
        "positive": "Obstruction and Interference in Low Energy Models for Twisted Bilayer\n  Graphene: The electronic bands of twisted bilayer graphene (TBLG) with a large-period\nmoir\\'e superlattice fracture to form narrow Bloch minibands that are\nspectrally isolated by forbidden energy gaps from remote dispersive bands. When\nthese gaps are sufficiently large, one can study a band-projected Hamiltonian\nthat correctly represents the dynamics within the minibands. This inevitably\nintroduces nontrivial geometrical constraints that arise from the assumed form\nof the projection. Here we show that this choice has a profound consequence in\na low-energy experimentally-observable signature which therefore can be used to\ntightly constrain the analytic form of the appropriate low-energy theory. We\nfind that this can be accomplished by a careful analysis of the electron\ndensity produced by backscattering of Bloch waves from an impurity potential\nlocalized on the moir\\'e superlattice scale. We provide numerical estimates of\nthe effect that can guide experimental work to clearly discriminate between\ncompeting models for the low-energy band structure."
    },
    {
        "anchor": "Electronic structure of monolayer antimonene nanoribbons under\n  out-of-plane and transverse bias: A systematic study of the electronic properties of single layer Sb\n(antimonene) nanoribbons is presented. By using a 6-orbital tight-binding\nHamiltonian, we study the electronic band structure of finite ribbons with\nzigzag or armchair termination. We show that there is good agreement between ab\ninitio calculations and the tight-binding model. We study how the size of the\ngap can be controlled by applying an external bias potential. An electric field\napplied perpendicular to the antimonene layer is found to increase the band\ngap, while a transverse bias potential leads to a position dependent reduction\nof the band gap. Both kinds of bias potential break inversion symmetry of the\ncrystal. This, together with the strong intrinsic spin-orbit coupling of\nantimonene, leads to spin-splitting of the valence band states.",
        "positive": "Strong entanglement of spins inside a quantum domain wall: Magnetic domain walls (DWs) are widely regarded as classical objects in\nphysics community, even though the concepts of electron spins and spin-spin\nexchange interaction are quantum mechanical in nature. One intriguing question\nis whether DWs can survive at the quantum level and acquire the quantum\nproperties such as entanglement. Here we show that spins within a DW are highly\nentangled in their quantum description. The total magnetization of a magnetic\nDW is nonzero, which is a manifestation of the global entanglement of the\ncollective spin state. These results significantly deepen our understanding of\nmagnetic DWs and enable the application of DWs in quantum information science.\nThe essential physics can be generalized to skyrmions so that they can also\nplay a role in quantum information processing."
    },
    {
        "anchor": "Tuning the exciton g-factor in single InAs/InP quantum dots: Photoluminescence data from single, self-assembled InAs/InP quantum dots in\nmagnetic fields up to 7 T are presented. Exciton g-factors are obtained for\ndots of varying height, corresponding to ground state emission energies ranging\nfrom 780 meV to 1100 meV. A monotonic increase of the g-factor from -2 to +1.2\nis observed as the dot height decreases. The trend is well reproduced by sp3\ntight binding calculations, which show that the hole g-factor is sensitive to\nconfinement effects through orbital angular momentum mixing between the\nlight-hole and heavy-hole valence bands. We demonstrate tunability of the\nexciton g-factor by manipulating the quantum dot dimensions using pyramidal InP\nnanotemplates.",
        "positive": "Structural, electronic, and optical properties of $m$-plane InGaN/GaN\n  quantum wells: Insights from experiment and atomistic theory: In this paper we present a detailed analysis of the structural, electronic,\nand optical properties of an $m$-plane (In,Ga)N/GaN quantum well structure\ngrown by metal organic vapor phase epitaxy. The sample has been structurally\ncharacterized by x-ray diffraction, scanning transmission electron microscopy,\nand 3D atom probe tomography. The optical properties of the sample have been\nstudied by photoluminescence (PL), time-resolved PL spectroscopy, and polarized\nPL excitation spectroscopy. The PL spectrum consisted of a very broad PL line\nwith a high degree of optical linear polarization. To understand the optical\nproperties we have performed atomistic tight-binding calculations, and based on\nour initial atom probe tomography data, the model includes the effects of\nstrain and built-in field variations arising from random alloy fluctuations.\nFurthermore, we included Coulomb effects in the calculations. Our microscopic\ntheoretical description reveals strong hole wave function localization effects\ndue to random alloy fluctuations, resulting in strong variations in ground\nstate energies and consequently the corresponding transition energies. This is\nconsistent with the experimentally observed broad PL peak. Furthermore, when\nincluding Coulomb contributions in the calculations we find strong exciton\nlocalization effects which explain the form of the PL decay transients.\nAdditionally, the theoretical results confirm the experimentally observed high\ndegree of optical linear polarization. Overall, the theoretical data are in\nvery good agreement with the experimental findings, highlighting the strong\nimpact of the microscopic alloy structure on the optoelectronic properties of\nthese systems."
    },
    {
        "anchor": "Conductivity fluctuations in proton-implanted ZnO microwires: The electric noise can be an important limitation for applications of\nconducting elements of size in the nanometer range. The intrinsic electrical\nnoise of prospective materials for opto-spintronics applications like ZnO has\nnot been characterized yet. In this study we have investigated the conductivity\nfluctuations in 10~nm thick current paths produced by proton implantation of\nZnO microwires at room temperature. The voltage noise under a constant dc\ncurrent bias in undoped as well as in Li-doped microwires is characterized by\n$1/f^a$ power spectra with $a \\sim 1$. The noise intensity scales with the\nsquare of the bias current pointing out to bias-independent resistivity\nfluctuations as a source of the observed noise. The normalized power spectral\ndensity appears inversely proportional to the number of carriers in the probed\nsample volume, in agreement with the phenomenological Hooge law. For the\nproton-implanted ZnO microwire and at 1~Hz we obtain a normalized power\nspectral density as low as $\\sim 10^{-11}~$Hz$^{-1}$.",
        "positive": "Quantum-dot lithium in strong-interaction regime: Depolarization of\n  electron spins by magnetic field: Magnetic field usually leads to a polarization of electron spins. It is shown\nthat in a system of {\\em strongly interacting} particles applying magnetic\nfield may lead to an opposite effect -- depolarization of electron spins.\nResults of the work are based on an exact-diagonalization study of quantum-dot\nlithium -- a system of three Coulomb interacting two-dimensional electrons in a\nparabolic confinement potential."
    },
    {
        "anchor": "RKKY signals characterizing the topological phase transitions in Floquet\n  Dirac semimetals: Recently, the Floquet ${\\rm Na_3Bi}$-type material has been proposed as an\nideal platform for realizing various phases, i.e., the spin-degenerate Dirac\nsemimetal (DSM) can be turned into the Weyl semimetal (WSM), and even to the\nWeyl half-metal (WHM). Instead of the conventional electrical methods, we use\nthe RKKY interaction to characterize the topological phase transitions in this\npaper. It is found that detecting the Ising term $J_I$ is feasible for\ndistinguishing the phase transition of DSM/WSM, since the emergence of $J_I$ is\ninduced by the broken spin degeneracy. For the case with impurities deposited\non $z$ axis (the line connecting the Weyl points), the Heisenberg term $J_H$\ncoexists with $J_I$ in the WSM, while $J_H$ is filtered out and only $J_I$\nsurvives in the WHM. This magnetic filtering effect is a reflection of the\nfully spin-polarized property (one spin band is in the WSM phase while the\nother is gapped) of the WHM, and it can act a signal to capture the phase\ntransition of WSM/WHM. This signal can not be disturbed unless the direction of\nthe impurities greatly deviates from $z$ axis. Interestingly, as the impurities\nare moved into the $x$-$y$ plane, there arises another signal (a dip structure\nfor $J_H$ at the phase boundary), which can also identify the phase transition\nof WSM/WHM. Furthermore, we have verified that all magnetic signals are robust\nto the term that breaks the electron-hole symmetry. Besides characterizing the\nphase transitions, our results also suggest that the Floquet DSMs are power\nplatforms for controlling the magnetic interaction.",
        "positive": "Valley-dependent transport in strain engineering graphene\n  heterojunctions: We study the effect of the strain on the band structure and the\nvalley-dependent transport property of graphene heterojunctions. It is found\nthat valley-dependent separation of electrons can be achieved by utilizing the\nstrain and on-site energies. In the presence of the strain, the values of the\ntransmission can be effectively adjusted by changing the strengths of the\nstrain, while the transport angle basically keeps unchanged. When an extra\non-site energy is simultaneously applied to the central scattering region, not\nonly are the electrons of valleys K and K' separated into two distinct\ntransmission lobes in opposite transverse directions, but the transport angles\nof two valleys can be significantly changed. Therefore, one can realize an\neffective modulation of valley-dependent transport by changing the strength and\nstretch angle of the strain and on-site energies, which can be exploited for\ngraphene-based valleytronics devices."
    },
    {
        "anchor": "Directional spontaneous emission in photonic crystal slabs: Spontaneous emission is one of the most fundamental out-of-equilibrium\nprocesses in which an excited quantum emitter relaxes to the ground state due\nto quantum fluctuations. In this process, a photon is emitted that can interact\nwith other nearby emitters and establish quantum correlations between them,\ne.g., via super and subradiance effects. One way to modify these\nphoton-mediated interactions is to alter the dipole radiation patterns of the\nemitter, e.g., by placing photonic crystals near them. One recent example is\nthe generation of strong directional emission patterns-key to enhancing super\nand subradiance effects-in two dimensions by employing photonic crystals with\nband structures characterized by linear isofrequency contours and\nsaddle-points. However, these studies have predominantly used oversimplified\ntoy models, overlooking the electromagnetic field's intricacies in actual\nmaterials, including aspects like geometrical dependencies, emitter positions,\nand polarization. Our study delves into the interaction between these\ndirectional emission patterns and the aforementioned variables, revealing the\nuntapped potential to fine-tune collective quantum optical phenomena.",
        "positive": "Bias and temperature dependence of the noise in a single electron\n  transistor: A single electron transistor based on Al-AlO_x-Nb tunnel junctions was\nfabricated by shadow evaporation and in situ barrier formation. Its output\ncurrent noise was measured, using a transimpedance amplifier setup, as a\nfunction of bias voltage, gain, and temperature, in the frequency range 1...300\nHz. The spot noise at 10 Hz is dominated by a gain dependent component,\nindicating that the main noise contribution comes from fluctuations at the\ninput of the transistor. Deviations from ideal input charge noise behaviour are\nfound in the form of a bias dependence of the differential charge equivalent\nnoise, i. e. the derivative of current noise with respect to gain. The\ntemperature dependence of this effect could indicate that heating is activating\nthe noise sources, and that they are located inside or in the near vicinity of\nthe junctions."
    },
    {
        "anchor": "Mid-Infrared Radiative Emission from Bright Hot Plasmons in Graphene: The decay dynamics of excited carriers in graphene have attracted wide\nscientific attention, as the gapless Dirac electronic band structure opens up\nrelaxation channels that are not allowed in conventional materials. We report\nFermi-level-dependent mid-infrared emission in graphene originating from a\npreviously unobserved decay channel: hot plasmons generated from optically\nexcited carriers. The observed Fermi-level dependence rules out Planckian light\nemission mechanisms and is consistent with the calculated plasmon emission\nspectra in photoinverted graphene. Evidence for bright hot plasmon emission is\nfurther supported by Fermi-level-dependent and polarization-dependent resonant\nemission from graphene plasmonic nanoribbon arrays under pulsed laser\nexcitation. Spontaneous plasmon emission is a bright emission process as our\ncalculations for our experimental conditions indicate that the spectral flux of\nspontaneously generated plasmons is several orders of magnitude higher than\nblackbody emission at a temperature of several thousand Kelvin. In this work,\nit is shown that a large enhancement in radiation efficiency of graphene\nplasmons can be achieved by decorating graphene surface with gold nanodisks,\nwhich serve as out-coupling scatterers and promote localized plasmon excitation\nwhen they are resonant with the incoming excitation light. These observations\nset a framework for exploration of ultrafast and ultrabright mid-infrared\nemission processes and light sources.",
        "positive": "Damping of Nanomechanical Resonators: We study the transverse oscillatory modes of nanomechanical silicon nitride\nstrings under high tensile stress as a function of geometry and mode index m <=\n9. Reproducing all observed resonance frequencies with classical elastic theory\nwe extract the relevant elastic constants. Based on the oscillatory local\nstrain we successfully predict the observed mode-dependent damping with a\nsingle frequency independent fit parameter. Our model clarifies the role of\ntensile stress on damping and hints at the underlying microscopic mechanisms."
    },
    {
        "anchor": "Transmission of a single electron through a Berry's ring: A theoretical model of transmission and reflection of an electron with spin\nis proposed for a mesoscopic ring with rotating localized magnetic moment. This\nmodel may be realized in a pair of domain walls connecting two ferromagnetic\ndomains with opposite magnetization. If the localized magnetic moment and the\ntraveling spin is ferromagnetically coupled and if the localized moment rotates\nwith opposite chirality in the double-path, our system is formulated in the\nmodel of an emergent spin-orbit interaction in a ring. The scattering problem\nfor the transmission spectrum of the traveling spin is solved both in a single\npath and a double path model. In the double path, the quantum-path interference\nchanges dramatically the transmission spectrum due to the effect of the Berry's\nphase. Specifically, the spin-flip transmission and reflection are both\nstrictly forbidden.",
        "positive": "Coherent Oscillations and Giant Edge Magnetoresistance in Singly\n  Connected Topological Insulators: The topological insulators have a gap in the bulk but extended states at the\nedge that can carry current. We study a geometry in which such edge states will\nmanifest themselves through periodic oscillations in the magnetoconductance of\na singly connected sample coupled to leads through narrow point contacts. The\noscillations occur due to quantum interference of helical edge states of\nelectrons traveling along the circumference of the sample, and have a period of\nB_0=h/eA_{eff}, where A_{eff} is the effective area enclosed by the edge states\nof the sample. Our calculation indicates the possibility of a large change in\nthe magnetoresistance at small B, termed giant edge magnetoresistance, which\ncan have potential for application. The zero field conductance also exhibits\noscillations as a function of the Fermi energy due to interference between edge\nstates. The amplitude of the oscillations is governed by, and therefore can be\nused to investigate, the transverse width of the edge channels."
    },
    {
        "anchor": "Edge Trapping of Exciton-Polariton Condensates in Etched Pillars: In this letter, we present a study of the condensation of exciton-polaritons\nin large etched pillar structures that exhibit shallow edge trapping. The\n$\\approx$ 100 $\\mu$m $\\times$ 100 $\\mu$m pillars were fabricated using\nphotolithography and a BCl$_3$/Cl$_2$ reactive ion etch. A low energy region\nemerged along the etched edge, with the minima $\\approx$ 7 $\\mu$m from the\nouter edge. The depth of the trap was 0.5-1.5 meV relative to the level central\nregion, with the deepest trapping at the corners. We were able to produce a\nBose-Einstein condensate in the trap near the edges and corners by pumping\nnon-resonantly in the middle of the pillar. This condensate began as a set of\ndisconnected condensates at various points along the edges, but then became a\nsingle mono-energetic condensate as the polariton density was increased.\nSimilar edge traps could be used to produce shallow 1D traps along edges or\nother more complex traps using various etch geometries and scales.",
        "positive": "Negative Photoconductance in van der Waals Heterostructures-Based\n  Floating Gate Phototransistor: Van der Waals (vdW) heterostructures made of two-dimensional materials have\nbeen demonstrated to be versatile architectures for optoelectronic applications\ndue to strong light-matter interactions. However, most of light-controlled\nphenomena and applications in the vdW heterostructures rely on positive\nphotoconductance (PPC). Negative photoconductance (NPC) has not yet been\nreported in vdW heterostructures. Here we report the observation of the NPC in\nReS2/h-BN/MoS2 vdW heterostructures-based floating gate phototransistor. The\nfabricated devices exhibit excellent performance of nonvolatile memory without\nlight illumination. More interestingly, we observe a gate-tunable transition\nbetween the PPC and the NPC under the light illumination. The observed NPC\nphenomenon can be attributed to the charge transfer between floating gate and\nconduction channel. Furthermore, we show that the control of NPC through light\nintensity is promising in realization of light-tunable multi-bit memory\ndevices. Our results may enable potential applications in multifunctional\nmemories and optoelectronic devices."
    },
    {
        "anchor": "New Aspects of Photocurrent Generation at Graphene pn Junctions Revealed\n  by Ultrafast Optical Measurements: The unusual electrical and optical properties of graphene make it a promising\ncandidate for optoelectronic applications. An important, but as yet unexplored\naspect is the role of photo-excited hot carriers in charge and energy transport\nat graphene interfaces. Here, we perform time-resolved (~250 fs) scanning\nphotocurrent microscopy on a tunable graphene pn junction. The ultrafast\npump-probe measurements yield a photocurrent response time of ~1.5 ps at room\ntemperature increasing to ~4 ps at 20 K. Combined with the negligible\ndependence of photocurrent amplitude on environmental temperature this implies\nthat hot carriers rather than phonons dominate energy transport at high\nfrequencies. Gate-dependent pump-probe measurements demonstrate that both\nthermoelectric and built-in electric field effects contribute to the\nphotocurrent excited by laser pulses. The relative weight of each contribution\ndepends on the junction configuration. A single laser beam excitation also\ndisplays multiple polarity-reversals as a function of carrier density, a\nsignature of impact ionization. Our results enhance the understanding of\nnon-equilibrium electron dynamics, electron-electron interactions, and\nelectron-phonon interactions in graphene. They also determine fundamental\nlimits on ultrafast device operation speeds (~500 GHz) for potential\ngraphene-based photon detection, sensing, and communication.",
        "positive": "Spatial control of carrier capture in two-dimensional materials: Beyond\n  energy selection rules: Transition metal dichalcogenide monolayers have attracted wide attention due\nto their remarkable optical, electronic and mechanical properties. In these\nmaterials local strain distributions effectively form quasi zero-dimensional\npotentials, whose localized states may be populated by carrier capture from the\ncontinuum states. Using a recently developed Lindblad single-particle approach,\nhere we study the phonon-induced carrier capture in a MoSe$_2$ monolayer.\nAlthough one decisive control parameter is the energy selection rule, which\nlinks the energy of the incoming carriers to that of the final state via the\nemitted phonon, we show that additionally the spatio-temporal dynamics plays a\ncrucial role. By varying the direction of the incoming carriers with respect to\nthe orientation of the localized potential, we introduce a new control\nmechanism for the carrier capture: the spatial control."
    },
    {
        "anchor": "Bichromatic Microwave Photoresistance of Two-Dimensional Electron System: We explore experimentally bichromatic (frequencies $\\omega_1$ and $\\omega\n_2$) photoresistance of a two-dimensional electron system in the regimes of\nmicrowave-induced resistance oscillations and zero-resistance states. We find\nbichromatic resistance to be well described by a superposition of $\\omega_1$\nand $\\omega_2$ components, provided that both monochromatic resistances are\npositive. This relation holds even when the oscillation amplitudes are small\nand one could expect additive contributions from monochromatic\nphotoresistances. In contrast, whenever a zero-resistance state is formed by\none of the frequencies, such superposition relation breaks down and the\nbichromatic resistance is strongly suppressed.",
        "positive": "Acoustic excitation and electrical detection of spin waves and spin\n  currents in hypersonic bulk waves resonator with YIG/Pt system: We report on the self-consisted semi-analytical theory of magnetoelastic\nexcitation and electrical detection of spin waves and spin currents in\nhypersonic bulk acoustic waves resonator with ZnO-GGG-YIG/Pt layered structure.\nElectrical detection of acoustically driven spin waves occurs due to spin\npumping from YIG to Pt and inverse spin Hall (ISHE) effect in Pt as well as due\nto electrical response of ZnO piezotransducer. The frequency-field dependences\nof the resonator frequencies and ISHE voltage $U_{ISHE}$ are correlated with\nexperimental ones observed previously. Their fitting allows to determine some\nmagnetic and magnetoelastic parameters of YIG. The analysis of the YIG film\nthickness influence on $U_{ISHE}$ gives the possibility to find the optimal\nthickness for maximal $U_{ISHE}$ value."
    },
    {
        "anchor": "Transport and elastic scattering times as probes of the nature of\n  impurity scattering in single and bilayer graphene: Both transport $\\tau_{tr}$ and elastic scattering times $\\tau_{e}$ are\nexperimentally determined from the carrier density dependence of the\nmagnetoconductance of monolayer and bilayer graphene. Both times and their\ndependences in carrier density are found to be very different in the monolayer\nand the bilayer. However their ratio $\\tau_{tr}/\\tau_{e} $is found to be of the\norder of $1.5 $ in both systems and independent of the carrier density. These\nmeasurements give insight on the nature (neutral or charged) and spatial extent\nof the scattering centers. Comparison with theoretical predictions yields that\nthe main scattering mechanism in our graphene samples could be due to strong\nscatterers of short range, inducing resonant scattering, a likely candidate\nbeing vacancies.",
        "positive": "Terahertz phonon engineering and spectroscopy with van der Waals\n  heterostructures: Phononic engineering at GHz frequencies form the foundation of microwave\nacoustic filters, high-speed acousto-optic modulators, and quantum transducers.\nTHz phononic engineering could lead to acoustic filters and modulators at\nhigher bandwidth and speed, as well as quantum circuits operating at higher\ntemperatures. It can also enable new ways to manipulate and control thermal\ntransport, as THz acoustic phonons are the main heat carriers in nonmetallic\nsolids. Despite its potential, methods for engineering THz phonons have been\nlittle explored due to the challenges of achieving the required material\ncontrol at sub-nanometer precision and efficient phonon coupling at THz\nfrequencies. Here, we demonstrate efficient generation, detection, and\nmanipulation of THz phonons through precise integration of atomically thin\nlayers in van der Waals heterostructures. We employ few-layer graphene as an\nultrabroadband transducer, converting fs near-infrared pulses to broadband\nacoustic phonon pulses with spectral content up to 3 THz. A single layer of\nWSe$_2$ is used as a sensor, where high-fidelity readout is enabled by the\nexciton-phonon coupling and strong light-matter interactions. By combining\nthese capabilities in a single van der Waals heterostructure and detecting\nresponses to incident mechanical waves, we performed THz phononic spectroscopy,\nsimilar to conventional optical spectroscopy which detects responses to\nincident electromagnetic waves. We demonstrate high-Q THz phononic cavities\nusing hBN stacks. We further show that a single layer of WSe$_2$ embedded in\nhBN can efficiently block the transmission of THz phonons. By comparing our\nmeasurements to a nanomechanical model, we obtain the important force constants\nat the heterointerfaces. Our results could enable THz phononic metamaterials\nbased on van der Waals heterostructures, as well as novel routes for thermal\nengineering."
    },
    {
        "anchor": "Electrically tunable three-dimensional g-factor anisotropy in single\n  InAs self-assembled quantum dots: Three-dimensional anisotropy of the Lande g-factor and its electrical\nmodulation are studied for single uncapped InAs self-assembled quantum dots\n(QDs). The g-factor is evaluated from measurement of inelastic cotunneling via\nZeeman substates in the QD for various magnetic field directions. We find that\nthe value and anisotropy of the g-factor depends on the type of orbital state\nwhich arises from the three-dimensional confinement anisotropy of the QD\npotential. Furthermore, the g-factor and its anisotropy are electrically tuned\nby a side-gate which modulates the confining potential.",
        "positive": "Transition from a fractional quantum Hall liquid to an electron solid at\n  Landau level filling nu = 1/3 in tilted magnetic fields: We have observed in a low density two-dimensional hole system (2DHS) of\nextremely high quality (with hole density p=1.6x10^{10} cm^{-2} and mobility\n\\mu=0.8x10^6 cm^2/Vs) that, as the 2DHS is continuously tilted with respect to\nthe direction of the magnetic field, the \\nu=1/3 fractional quantum Hall effect\n(FQHE) state is weakened and its magnetoresistivity rises from ~ 0.4\nkohm/square in the normal orientation to ~ 180 kohm/square at tilt angle \\theta\n\\~ 80 degrees. We attribute this phenomenon to the transition of the 2DHS from\nthe FQHE liquid state to the pinned Wigner solid state, and argue that its\norigin is the strong coupling of subband Landau levels under the tilted\nmagnetic fields."
    },
    {
        "anchor": "Majorana-Josephson Interferometer: We propose an interferometer for chiral Majorana modes where the interference\neffect is caused and controlled by a Josephson junction of proximity-induced\ntopological superconductors, hence, a Majorana-Josephson interferometer. This\ninterferometer is based on a two-terminal quantum anomalous Hall bar, and as\nsuch its transport observables exhibit interference patterns depending on both\nthe Josephson phase and the junction length. Observing these interference\npatterns will establish quantum coherent Majorana transport and further provide\na powerful characterization tool for the relevant system.",
        "positive": "Exciton Transfer in Array of Epitaxially Connected Nanocrystals: Recently, epitaxially connected at facets semiconductor nanocrystals (NCs)\nhave been introduced to fascilitate the electron transport between\nnanocrystals. To fully deploy their potential a better understanding of the\nexciton transfer between connected NCs is needed. We go beyond the two\nwell-known transfer mechanisms suggested by F\\\"orster and Dexter and propose a\nthird mechanism of exciton tandem tunneling. The tandem tunnelling occurs\nthrough the intermediate state in which electron and hole are in different NCs.\nThe corresponding rate for exciton hops is larger than the Dexter rate and for\nSi is even much larger that the F\\\"orster one."
    },
    {
        "anchor": "Spin-Orbit Coupling and Tunneling Current in a Parabolic Quantum Dot: We propose a novel approach to explore the properties of a quantum dot in the\npresence of the spin-orbit interaction and in a tilted magnetic field. The\nspin-orbit coupling within the quantum dot manifest itself as anti-crossing of\nthe energy levels when the tilt angle is varied. The anti-crossing gap has a\nnon-monotonic dependence on the magnitude of the magnetic field and exhibits a\npeak at some finite values of the magnetic field. From the dependence of the\ntunneling current through the quantum dot on the bias voltage and the tilt\nangle, the anti-crossing gap and most importantly the spin-orbit strength can\nbe uniquely determined.",
        "positive": "Berry Phase and Anomalous Transport of the Composite Fermions at the\n  Half-Filled Landau Level: The fractional quantum Hall effect (FQHE) in two-dimensional electron system\n(2DES) is an exotic, superfluid-like matter with an emergent topological order.\nFrom the consideration of Aharonov-Bohm interaction of electrons and magnetic\nfield, the ground state of a half-filled lowest Landau level is mathematically\ntransformed to a Fermi sea of composite objects of electrons bound to two flux\nquanta, termed composite fermions (CFs). A strong support for the CF theories\ncomes from experimental confirmation of the predicted Fermi surface at $\\nu$ =\n1/2 (where $\\nu$ is the Landau level filling factor) from the detection of the\nFermi wave vector in the semi-classical geometrical resonance experiments.\nRecent developments in the theory of CFs have led to a prediction of a $\\pi$\nBerry phase for the CF circling around the Fermi surface at half-filling. In\nthis paper we provide the first experimental evidence for the detection of the\nBerry phase of CFs in the fractional quantum Hall effect. Our measurements of\nthe Shubnikov-de Haas oscillations of CFs as a function carrier density at a\nfixed magnetic field provide a strong support for an existence of a $\\pi$ Berry\nphase at $\\nu$ = 1/2. We also discover that the conductivity of composite\nfermions at $\\nu$ = 1/2 displays an anomalous linear density dependence, whose\norigin remains mysterious yet tantalizing."
    },
    {
        "anchor": "Towards Realizing a Quantum Memory for a Superconducting Qubit: Storage\n  and Retrieval of quantum states: We have built a hybrid system composed of a superconducting flux qubit (the\nprocessor) and an ensemble of nitrogen-vacancy centers in diamond (the memory)\nthat can be directly coupled to one another and demonstrated how information\ncan be transferred from the flux qubit to the memory, stored and subsequently\nretrieved. We have established the coherence properties of the memory, and\nsucceeded in creating an entangled state between the processor and memory,\ndemonstrating how the entangled state's coherence is preserved. Our results are\na significant step towards using an electron spin ensemble as a quantum memory\nfor superconducting qubits.",
        "positive": "Optomechanical lasing and domain walls driven by exciton-phonon\n  interactions: We study theoretically interaction of optically-pumped excitons with acoustic\nwaves in planar semiconductor nanostructures in the strongly nonlinear regime.\nWe start with the multimode optomechanical lasing regime for optical pump\nfrequency {above} the exciton resonance and demonstrate broadband chaotic-like\nlasing spectra. We also predict formation of propagating optomechanical domain\nwalls driven by optomechanical nonlinearity for the optical pump {below} the\nexciton resonance. Stability conditions for the domain walls are examined\nanalytically and are in agreement with direct numerical simulations. Our\nresults apply to nonlinear sound propagation in the arrays of quantum wells or\nin the plane of Bragg semiconductor microcavities hosting excitonic polaritons."
    },
    {
        "anchor": "Coulomb Blockade Peak Spacing Distribution: The Interplay of Temperature\n  and Spin: We calculate the Coulomb Blockade peak spacing distribution at finite\ntemperature using the recently introduced ``universal Hamiltonian'' to describe\nthe e-e interactions. We show that the temperature effect is important even at\nkT~0.1\\Delta (\\Delta is the single-particle mean level spacing). This\nsensitivity arises because: (1) exchange reduces the minimum energy of\nexcitation from the ground state and (2) the entropic contribution depends on\nthe change of the spin of the quantum dot. Including the leading corrections to\nthe universal Hamiltonian yields results in quantitative agreement with the\nexperiments. Surprisingly, temperature appears to be the most important effect.",
        "positive": "Scanning-gate-induced effects and spatial mapping of a cavity: Tailored electrostatic potentials are the foundation of scanning gate\nmicroscopy. We present several aspects of the tip-induced potential on the\ntwo-dimensional electron gas. First, we give methods on how to estimate the\nsize of the tip-induced potential. Then, a ballistic cavity is formed and\nstudied as a function of the bias-voltage of the metallic top gates and probed\nwith the tip-induced potential. It is shown how the potential of the cavity\nchanges by tuning the system to a regime where conductance quantization in the\nconstrictions formed by the tip and the top gates occurs. This conductance\nquantization leads to a unprecedented rich fringe pattern over the entire\nstructure. Finally, the effect of electrostatic screening of the metallic top\ngates is discussed."
    },
    {
        "anchor": "Optimisation of electrically-driven multi-donor quantum dot qubits: Multi-donor quantum dots have been at the forefront of recent progress in\nSi-based quantum computation. Among them, $2P:1P$ qubits have a built-in dipole\nmoment, enabling all-electrical spin operation via hyperfine mediated electron\ndipole spin resonance (EDSR). The development of all-electrical multi-donor dot\nqubits requires a full understanding of their EDSR and coherence properties,\nincorporating multi-valley nature of their ground state. Here, by introducing a\nvariational effective mass wave-function, we examine the impact of qubit\ngeometry and nearby charge defects on the electrical operation and coherence of\n$2P:1P$ qubits. We report four outcomes: (i) The difference in the hyperfine\ninteraction between the $2P$ and $1P$ sites enables fast EDSR, with $T_\\pi \\sim\n10-50$ ns and a Rabi ratio $ (T_1/T_\\pi) \\sim 10^6$. We analyse qubits with the\n$2P:1P$ axis aligned along the [100], [110] and [111] crystal axes, finding\nthat the fastest EDSR time $T_\\pi$ occurs when the $2P:1P$ axis is\n$\\parallel$[111], while the best Rabi ratio occurs when it is $\\parallel$\n[100]. This difference is attributed to the difference in the wave function\noverlap between $2P$ and $1P$ for different geometries. In contrast, the choice\nof $2P$ axis has no visible impact on qubit operation. (ii) Sensitivity to\nrandom telegraph noise due to nearby charge defects depends strongly on the\nlocation of the nearby defects with respect to the qubit. For certain\norientations of defects random telegraph noise has an appreciable effect both\non detuning and $2P-1P$ tunneling, with the latter inducing gate errors. (iii)\nThe qubit is robust against $1/f$ noise provided it is operated away from the\ncharge anticrossing. (iv) Entanglement via exchange is several orders of\nmagnitude faster than dipole-dipole coupling. These findings pave the way\ntowards fast, low-power, coherent and scalable donor dot-based quantum\ncomputing.",
        "positive": "Ultrafast transient dynamics in composite multiferroics: We investigate theoretically the dynamic multiferroic response of coupled\nferroelectric/ferromagnetic composites upon excitation by a photo-induced\nacoustic strain pulse. Two magnetoelectric mechanisms are considered: interface\nstrain- and charge-mediated magnetoelectric couplings. The former results in\ndemagnetization, depolarization and repolarization within tens of picoseconds\nvia respectively magnetostriction and piezoelectricity. Charge magnetoelectric\ninteraction affects the ferroelectric/ferromagnetic feedback response leading\nto magnetization recovery. Experimental realization based on time-resolved\nx-ray diffraction is suggested. The findings indicate the potential of\ncomposite multiferroics for photo-steered, high-speed, multi-state electronic\ndevices."
    },
    {
        "anchor": "Spin-orbit effects in nanowire-based wurtzite semiconductor quantum dots: We study the effect of the Dresselhaus spin-orbit interaction on the\nelectronic states and spin relaxation rates of cylindrical quantum dots defined\non quantum wires having wurtzite lattice structure. The linear and cubic\ncontributions of the bulk Dresselhaus spin-orbit coupling are taken into\naccount, along with the influence of a weak external magnetic field. The\npreviously found analytic solution for the electronic states of cylindrical\nquantum dots with zincblende lattice structures with Rashba interaction is\nextended to the case of quantum dots with wurtzite lattices. For the electronic\nstates in InAs dots, we determine the spin texture and the effective g-factor,\nwhich shows a scaling collapse when plotted as a function of an effective\nrenormalized dot-size dependent spin-orbit coupling strength. The\nacoustic-phonon-induced spin relaxation rate is calculated and the transverse\npiezoelectric potential is shown to be the dominant one.",
        "positive": "Multiphoton processes at cyclotron resonance subharmonics in a 2D\n  electron system under DC and microwave excitation: We investigate a two-dimensional electron system (2DES) under microwave\nillumination at cyclotron resonance subharmonics. The 2DES carries sufficient\ndirect current, $I$, that the differential resistivity oscillates as $I$ is\nswept. At magnetic fields sufficient to resolve individual Landau levels, we\nfind the number of oscillations within an $I$ range systematically changes with\nincreasing microwave power. Microwave absorption and emission of $N$ photons,\nwhere $N$ is controlled by the microwave power, describes our observations in\nthe framework of the displacement mechanism of impurity scattering between\nHall-field tilted Landau levels."
    },
    {
        "anchor": "Theory of Tunneling in the Exciton Condensate of Bilayer Quantum Hall\n  Systems: We develop a theory of interlayer tunneling in the exciton condensate of\nbilayer quantum Hall systems, which predicts strongly enhanced, but finite,\ntunneling conductance peaks near zero bias even at zero temperature. It is\nemphasized that, though this strongly enhanced tunneling originates from\nspontaneous interlayer phase coherence, it is fundamentally not the Josephson\neffect. Because of strong interlayer correlation, the bilayer system behaves as\na single system so that conventional tunneling theories treating two layers as\nindependent systems are not applicable. Based on our theory, we compute the\nheight of conductance peak as a function of interlayer distance, which is in\ngood agreement with experiment.",
        "positive": "Electrical control of phonon mediated spin relaxation rate in\n  semiconductor quantum dots: the Rashba vs the Dresselhaus spin-orbit\n  couplings: In symmetric quantum dots (QDs), it is well known that the spin-hot spot\n(i.e., the cusp-like structure due to the presence of degeneracy near the level\nor anticrossing point) is present for the pure Rashba case but is absent for\nthe pure Dresselhaus case [Phys. Rev. Lett. 95, 076805 (2005)]. Since the\nDresselhaus spin-orbit coupling dominates over the Rashba spin-orbit coupling\nin GaAs and GaSb QDs, it is important to find the exact location of the\nspin-hot spot or the cusp-like structure even for the pure Dresselhaus case. In\nthis paper, for the first time, we present analytical and numerical results\nthat show that the spin-hot spot can also be seen for the pure Dresselhaus\nspin-orbit coupling case by inducing large anisotropy through external gates.\nAt or nearby the spin-hot spot, the spin transition rate enhances and the\ndecoherence time reduces by several orders of magnitude compared to the case\nwith no spin-hot spot. Thus one should avoid such locations when designing QD\nspin based transistors for the possible implementation in quantum logic gates,\nsolid state quantum computing and quantum information processing. It is also\npossible to extract the exact experimental data (Phys. Rev. Lett. 100, 046803\n(2008)) for the phonon mediated spin-flip rates from our developed theoretical\nmodel."
    },
    {
        "anchor": "Charging of graphene by magnetic field and mechanical effect of magnetic\n  oscillations: We discuss the fact that quantum capacitance of graphene-based devices leads\nto variation of it's charge density under changes of external magnetic\nfield.The charge is conserved, but redistributes to substrate or other graphene\nsheet. We derive exact analytic expression for charge redistribution in the\ncase of ideal graphene in strong magnetic field. When we account for impurities\nand temperature, the effect decreases and the formulae reduce to standard\nquantum capacitance expressions. The importance of quantum capacitance for\npotential Casimir force experiments is emphasized and an application of atomic\nforce microscope technique for measurement of density of states is proposed.",
        "positive": "Tomonaga-Luttinger physics in electronic quantum circuits: In one-dimensional conductors, interactions result in correlated electronic\nsystems. At low energy, a hallmark signature of the so-called\nTomonaga-Luttinger liquids (TLL) is the universal conductance curve predicted\nin presence of an impurity. A seemingly different topic is the quantum laws of\nelectricity, when distinct quantum conductors are assembled in a circuit. In\nparticular, the conductances are suppressed at low energy, a phenomenon called\ndynamical Coulomb blockade (DCB). Here we investigate the conductance of\nmesoscopic circuits constituted by a short single-channel quantum conductor in\nseries with a resistance, and demonstrate a proposed link to TLL physics. We\nreformulate and establish experimentally a recently derived phenomenological\nexpression for the conductance using a wide range of circuits, including carbon\nnanotube data obtained elsewhere. By confronting both conductance data and\nphenomenological expression with the universal TLL curve, we demonstrate\nexperimentally the predicted mapping between DCB and the transport across a TLL\nwith an impurity."
    },
    {
        "anchor": "Hamiltonian Theory of the Fractional Quantum Hall Effect: Effect of\n  Landau Level Mixing: We derive an effective hamiltonian in the Lowest Landau Level (LLL) that\nincorporates the effects of Landau-level mixing to all higher\n  Landau levels to leading order in the ratio of interaction energy to the\ncyclotron energy. We then transcribe the hamiltonian to the composite fermion\nbasis using our hamiltonian approach and compute the effect of LL mixing on\ntransport gaps.",
        "positive": "Layer Coherence Origin of Intrinsic Planar Hall Effect in 2D Limit: The intrinsic planar Hall effect has attracted intensive interest inspired by\nrecent experiments. Existing theories of this effect require three dimensional\norbital motion, or strong spin-orbit coupling of certain forms, which do not\nexist in van der Waals thin films. Here, we uncover a new origin of the planar\nHall effect - as an intrinsic property of layer coherent electrons - that\nallows its presence even in bilayer and trilayer atomically thin limit. As\nexamples, we show that the effect can be triggered by strain and interlayer\nsliding respectively in twisted bilayer graphene and trilayer transition metal\ndichalcogenides, where the effect features rich tunability and even stronger\nmagnitude than those induced by topological nodal structures in bulk materials.\nThe layer mechanism also provides a new route towards quantized Hall response\nupon a topological phase transition induced by in-plane magnetic field. These\nresults unveil the unexplored potential of quantum layertronics and moir\\'e\nflat band for planar Hall transport."
    },
    {
        "anchor": "Composite Fermions with Spin Freedom: General rule for the composite fermion transformation, when the spins of the\nelectrons are not polarized is derived. Condition for the quantum phase\ntransition between various spin states is obtained based on the rule. This rule\ngives foundation for the experimental determination of the mass and $g$-factor\nof the composite fermion.",
        "positive": "Non-Abelian $\u03bd=1/2$ quantum Hall state in $\u0393_8$ Valence Band Hole\n  Liquid: In search of states with non-Abelian statistics, we explore the fractional\nquantum Hall effect in a system of two-dimensional charge carrier holes. We\npropose a new method of mapping states of holes confined to a finite width\nquantum well in a perpendicular magnetic field to states in a spherical shell\ngeometry. This method provides single-particle hole states used in exact\ndiagonalization of systems with a small number of holes in the presence of\nCoulomb interactions. An incompressible fractional quantum Hall state emerges\nin a hole liquid at the half-filling of the ground state in a magnetic field in\nthe range of fields where single-hole states cross. This state has a negligible\noverlap with the Halperin 331 state, but a significant overlap with the\nMoore-Read Pfaffian state. Excited fractional quantum Hall states for small\nsystems have sizable overlap with non-Abelian excitations of the Moore-Read\nPfaffian state."
    },
    {
        "anchor": "Transport properties of Majorana bound states networks in the Coulomb\n  blockade regime: Topologically protected qubits based on nanostructures hosting Majorana bound\nstates (MBSs) hold great promise for fault-tolerant quantum computing. We study\nthe transport properties of nanowire networks hosting MBSs with a focus on the\neffects of the charging energy and the overlap between neighboring MBSs in\nshort mesoscopic samples. In particular, we investigate structures hosting four\nMBSs such as T-junctions and Majorana boxes. Using a master equation in the\nMarkovian approximation, we discuss the leading transport processes mediated by\nthe MBSs. Single-electron tunneling and processes involving creation and\nannihilation of Cooper pairs dominate in the sequential tunneling limit. In the\ncotunneling regime the charge in the MBSs network is fixed and transport is\ngoverned by transitions via virtual intermediate states. Our results show that\nfour-terminal measurements in the T-junction and Majorana box geometries can be\nuseful tools for the characterization of the properties of MBSs with finite\noverlaps and charging energy.",
        "positive": "Hund and anti-Hund rules in circular molecules: We study the validity of Hund's first rule for the spin multiplicity in\ncircular molecules - made of real or artificial atoms such as quantum dots - by\nconsidering a perturbative approach in the Coulomb interaction in the extended\nHubbard model with both on-site and long-range interactions. In this\napproximation, we show that an anti-Hund rule {\\it always} defines the ground\nstate in a molecule with $4N$ atoms at half-filling. In all other cases (i.e.\nnumber of atoms {\\it not} multiple of four, or a $4N$ molecule away from\nhalf-filling) both the singlet and the triplet outcomes are possible, as\ndetermined {primarily} by the total number of electrons in the system. In some\ninstances, the Hund rule is always obeyed and the triplet ground state is\nrealized {\\it mathematically} for any values of the on-site and long range\ninteractions, while for other filling situations the singlet is also possible\nbut only if the long-range interactions exceed a certain threshold, relatively\nto the on-site interaction."
    },
    {
        "anchor": "SU(4) spin waves in the $\u03bd=\\pm1$ quantum Hall ferromagnet in graphene: We study generalized spin waves in graphene under a strong magnetic field\nwhen the Landau-level filling factor is $\\nu=\\pm 1$. In this case, the ground\nstate is a particular SU(4) quantum Hall ferromagnet, in which not only the\nphysical spin is fully polarized but also the pseudo-spin associated with the\nvalley degree of freedom. The nature of the ground state and the spin-valley\npolarization depend on explicit symmetry breaking terms that are also reflected\nin the generalised spin-wave spectrum. In addition to pure spin waves, one\nencounters valley-pseudo-spin waves as well as more exotic entanglement waves\nthat have a mixed spin-valley character. Most saliently, the SU(4)\nsymmetry-breaking terms do not only yield gaps in the spectra, but under\ncertain circumstances, namely in the case of residual ground-state symmetries,\nrender the originally quadratic (in the wave vector) spin-wave dispersion\nlinear.",
        "positive": "Finite size effects of helical edge states in HgTe/CdTe quantum wells: The solutions for the helical edge states for an effective continuum model\nfor the quantum spin Hall effect in HgTe/CdTe quantum wells are presented. For\na sample of a large size, the solution gives the linear dispersion for the edge\nstates. However, in a finite strip geometry, the edge states at two sides will\ncouple with each other, which leads to a finite energy gap in the spectra. The\ngap decays in an exponential law of the width of sample. The magnetic field\ndependence of the edge states illustrates the difference of the edge states\nfrom those of a conventional quantum Hall strip of two-dimensional electron\ngas."
    },
    {
        "anchor": "Spintronic Oscillator Based on Magnetic Field Feedback: We present a circuit design of a spintronic oscillator based on magnetic\ntunnel junction. In this design, a dc current is passed through a magnetic\ntunnel junction which is connected to a feed-back wire below it. Any\nfluctuation in the magnetization direction of the free layer of MTJ, drives a\nfluctuating current through the feed-back wire, which exerts a magnetic field\non the free layer. This in turn can amplify the magnetization fluctuations of\nthe free layer. If the dc current passing through the MTJ is more than a\ncritical value, continuous precessing states of the magnetization are possible.",
        "positive": "Current-voltage characteristic and shot noise of shift current\n  photovoltaics: We theoretically study the current-voltage relation, $I-V$ characteristic, of\nthe photovoltaics due to the shift current, i.e., the photocurrent generated\n${\\it without}$ the external dc electric field in noncentrosymmetric crystals\nthrough the Berry connection of the Bloch wavefunctions. We find that the $I-V$\ncharacteristic and shot noise are controlled by the difference of group\nvelocities between conduction and valence bands, i.e., $v_{11}-v_{22}$, and the\nrelaxation time $\\tau$. Since the shift current itself is independent of these\nquantities, there are wide possibilities to design it to maximize the energy\nconversion rate and also to suppress the noise. We propose that the Landau\nlevels in noncentrosymmetric two-dimensional systems are the promising\ncandidate for energy conversion."
    },
    {
        "anchor": "Investigating thermal transport in knotted graphene nanoribbons using\n  non-equilibrium molecular dynamics: In this work, we investigated the effect of knots in the thermal transport of\ngraphene nanoribbons through non-equilibrium molecular dynamics simulations. We\nconsidered the cases of one, two, and three knots are present. Temperature\njumps appear in the temperature profile where the knots are located, which\nindicates that they introduce thermal resistances in the system, similar to\ninterfacial Kapitza resistance present between two different materials and/or\nsingle materials with defects and/or lattice distortions. We found that the\nthermal resistance introduced by each individual knot is essentially the same\nas the overall resistance increase linearly with the number of knots, as they\nbehave as thermal resistances associated in series. Also, the relative position\nbetween each knot in the arrangement does not strongly affect the thermal\ncurrent produced by the temperature gradient, showing a weak thermal\nrectification effect.",
        "positive": "Line Widths of Single-Electron Tunneling Oscillations: Experiment and\n  Numerical Simulations: We present experimental and numerical results from a real-time detection of\ntime-correlated single-electron tunneling oscillations in a one-dimensional\nseries array of small tunnel junctions. The electrons tunnel with a frequency\nf=I/e, where I is the current and e is the electron charge. Experimentally, we\nhave connected a single-electron transistor to the last array island, and in\nthis way measured currents from 5 fA to 1 pA by counting the single electrons.\nWe find that the line width of the oscillation is proportional to the frequency\nf. The experimental data agrees well with numerical simulations."
    },
    {
        "anchor": "Electronic and Optical Properties of Self-Assembled Quantum Wires: We have studied the band and optical properties of self-assembled quantum\nwires. In particular, the band structures and optical matrix elements of\nstrained multiple quantum-wires (QWR's) are investigated theoretically via the\neffective bond-orbital model(EBOM), which takes into account the effects of\nvalence-band anisotropy and the band mixing. It is found that the strain leads\nto further confinement of carriers and enhancement of the anisotropy.\n  By using the EBOM and valence-force field model, we systematically studied\nthe microstrain effects on the electronic and optical properties of\nGa$_{1-x}$In$_x$As self-assembled quantum-wires (QWR's) made of short-period\nsuperlattices with strain-induced lateral ordering. Valence-band anisotropy,\nband mixing, and effects due to local strain distribution at the atomistic\nlevel are all taken into account.A comprehensive collection of different\nstructures in our model are presented.\n  Finally, the excitonic absorption spectrum for the SILO quantum wires are\ninvestigated by using our envelope function model.",
        "positive": "Why does bulk boundary correspondence fail in some non-hermitian\n  topological models: Bulk boundary correspondence is crucial to topological insulator as it\nassociates the boundary states (with zero energy, chiral or helical) to\ntopological numbers defined in bulk. The application of this correspondence\nneeds a prerequisite condition which is usually not mentioned explicitly: the\nboundaries themselves cannot alter the bulk states, so as to the topological\nnumbers defined on them. In non-hermitian models with fractional winding\nnumber, we prove that such precondition fails and the bulk boundary\ncorrespondence is cut out. We show that, as eliminating the hopping between the\nboundaries to simulate the evolution of a system from the periodic boundary\ncondition to the open boundary condition, exceptional points must be passed\nthrough and the topological structure of the spectrum has been changed. This\nmakes the topological structures of a chain with open boundary totally\ndifferent from that without the boundary. We also argue that such exotic\nbehavior does not emerge when the open boundary is replaced by a domain-wall.\nSo the index theorem can be applied to the systems with domain-walls but cannot\nbe further used to those with open boundary."
    },
    {
        "anchor": "Quantum Monte-Carlo for correlated out-of-equilibrium nanoelectronics\n  devices: We present a simple, general purpose, quantum Monte-Carlo algorithm for\nout-of-equilibrium interacting nanoelectronics systems. It allows one to\nsystematically compute the expansion of any physical observable (such as\ncurrent or density) in powers of the electron-electron interaction coupling\nconstant $U$. It is based on the out-of-equilibrium Keldysh Green's function\nformalism in real-time and corresponds to evaluating all the Feynman diagrams\nto a given order $U^n$ (up to $n=15$ in the present work). A key idea is to\nexplicitly sum over the Keldysh indices in order to enforce the unitarity of\nthe time evolution. The method can easily reach long time, stationary regimes,\neven at zero temperature. We then illustrate our approach with an application\nto the Anderson model, an archetype interacting mesoscopic system. We recover\nvarious results of the literature such as the spin susceptibility or the \"Kondo\nridge\" in the current-voltage characteristics. In this case, we found the\nMonte-Carlo free of the sign problem even at zero temperature, in the\nstationary regime and in absence of particle-hole symmetry. The main limitation\nof the method is the lack of convergence of the expansion in $U$ for large $U$,\ni.e. a mathematical property of the model rather than a limitation of the\nMonte-Carlo algorithm. Standard extrapolation methods of divergent series can\nbe used to evaluate the series in the strong correlation regime.",
        "positive": "Design and performance of an ultra-high vacuum spin-polarized scanning\n  tunneling microscope operating at 30 mK and in a vector magnetic field: We describe the design and performance of a scanning tunneling microscope\n(STM) which operates at a base temperature of 30 mK in a vector magnetic field.\nThe cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution\nrefrigerator that contains a vector magnet allowing for fields up to 9 T\nperpendicular and 4 T parallel to the sample. The STM is placed in a\nmulti-chamber UHV system, which allows in-situ preparation and exchange of\nsamples and tips. The entire system rests on a 150-ton concrete block suspended\nby pneumatic isolators, which is housed in an acoustically isolated and\nelectromagnetically shielded laboratory optimized for extremely low noise\nscanning probe measurements. We demonstrate the overall performance by\nillustrating atomic resolution and quasiparticle interference imaging and\ndetail the vibrational noise of both the laboratory and microscope. We also\ndetermine the electron temperature via measurement of the superconducting gap\nof Re(0001) and illustrate magnetic field-dependent measurements of the spin\nexcitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin\nresolution by imaging the magnetic structure of the Fe double layer on W(110)."
    },
    {
        "anchor": "Charge noise analysis of an AlGaAs/GaAs quantum dot using\n  transmission-type radio-frequency single-electron transistor technique: Radio-frequency (rf)- operated single-electron transistors (SETs) are\nhigh-sensitivity, fast-response electrometers, which are valuable for\ndeveloping new insights into single-charge dynamics. We investigate\nhigh-frequency (up to 1 MHz) charge noise in an AlGaAs/GaAs quantum dot using a\ntransmission-type rf-SET technique. The electron capture and emission kinetics\non a trap in the vicinity of the quantum dot are dominated by a Poisson\nprocess. The maximum bandwidth for measuring single trapping events is about 1\nMHz, which is the same as that required for observing single-electron tunneling\noscillations in a measurable current (~0.1pA).",
        "positive": "Comment on \"Deformations of the spin currents by topological screw\n  dislocation and cosmic dispiration'': In this comment, we showed that the Dirac equation in the screw dislocation\nspace-time also carries a term that represents the torsion of such topological\ndefect, given by $K_\\mu$. Therefore, the Dirac equation worked by Wang et al.\nis incomplete since such a term was ignored in your equation (what cannot\nhappen). In other words, it is only possible to work with the Dirac equation in\nthe form presented by Wang et al. if the space-time is torsion-free, which is\nobviously not the case."
    },
    {
        "anchor": "Nonlocal optical responses of ultrapure metals in the hydrodynamic\n  regime: Our conventional understanding of optical responses in metals has been based\non the Drude theory. In recent years, however, it has become possible to\nprepare ultrapure metallic samples where the electron-electron scattering\nbecomes the most dominant process governing transport and thus the Drude\ntheory, where momentum-relaxing scatterings such as electron-impurity\nscattering are assumed to be dominant, is no longer valid. This regime is\ncalled the hydrodynamic regime and described by an emergent hydrodynamic\ntheory. Here, we develop a basic framework of optical responses in the\nhydrodynamic regime. Based on the hydrodynamic equation, we reveal the\nexistence of a ``hydrodynamic mode'' resulting from the viscosity effect and\ncompute the reflectance and the transmittance in three-dimensional electron\nfluids. Our theory also describes how to probe the hydrodynamic effects and\nmeasure the viscosity through simple optical techniques.",
        "positive": "Lateral p-n Junction in an Inverted InAs/GaSb Double Quantum Well: We present transport measurements on a lateral p-n junction in an inverted\nInAs/GaSb double quantum well at zero and nonzero perpendicular magnetic\nfields. At a zero magnetic field, the junction exhibits diodelike behavior in\naccordance with the presence of a hybridization gap. With an increasing\nmagnetic field, we explore the quantum Hall regime where spin-polarized edge\nstates with the same chirality are either reflected or transmitted at the\njunction, whereas those of opposite chirality undergo a mixing process, leading\nto full equilibration along the width of the junction independent of spin.\nThese results lay the foundations for using p-n junctions in InAs/GaSb double\nquantum wells to probe the transition between the topological quantum spin Hall\nand quantum Hall states."
    },
    {
        "anchor": "Controlling shot noise in double-barrier magnetic tunnel junctions: We demonstrate that shot noise in Fe/MgO/Fe/MgO/Fe double-barrier magnetic\ntunnel junctions is determined by the relative magnetic configuration of the\njunction and also by the asymmetry of the barriers. The proposed theoretical\nmodel, based on sequential tunneling through the system and including spin\nrelaxation, successfully accounts for the experimental observations for bias\nvoltages below 0.5V, where the influence of quantum well states is negligible.\nA weak enhancement of conductance and shot noise, observed at some voltages\n(especially above 0.5V), indicates the formation of quantum well states in the\nmiddle magnetic layer. The observed results open up new perspectives for a\nreliable magnetic control of the most fundamental noise in spintronic\nstructures.",
        "positive": "Sign reversal of Hall conductivity and quantum confinement in graphene\n  ribbons: Characterized by zigzag and armchair boundaries, the narrow ribbons display\nthe very different characteristics in Hall conductivities. It is shown that the\nmulti-band-crossings occur in the energy spectrum for armchair ribbons, and the\nnumber of them depends on the width of ribbons. Theoretically, it is predicated\nthat the conductivities exhibit drastic sign reversals for narrow ribbons as\nthe Fermi energy sweep over the band-crossings. A new classification of\narmchair ribbons is suggested based on the emergence of a flat band in the\nenergy spectrum only for odd armchair ribbons. The evolution of jumped Hall\nconductivities to step-like plateaus and the restore of density of states at\nthe van Hove singularity in the limitation to graphene sheet have been\nanalyzed."
    },
    {
        "anchor": "Protocol for high fidelity readout in the photon blockade regime of\n  circuit QED: The driven-damped Jaynes-Cummings model in the regime of strong coupling is\nfound to exhibit a coexistence between the quantum photon blockaded state and a\nquasi-coherent bright state. We characterize the slow time scales and the basin\nof attraction of these metastable states using full quantum simulations. This\nform of bistability can be useful for implementing a qubit readout scheme that\ndoes not require additional circuit elements. We propose a coherent control\nsequence that makes use of a simple linear chirp of drive amplitude and\nfrequency as well as qubit frequency. By optimizing the parameters of the\nsystem and the control pulse we demonstrate theoretically very high readout\nfidelities (>98%) and high contrast, with experimentally realistic parameters\nfor qubits implemented in the circuit QED architecture.",
        "positive": "Non-Hermitian skin effect of dislocations and its topological origin: We demonstrate that dislocations in two-dimensional non-Hermitian systems can\ngive rise to density accumulation or depletion through the localization of an\nextensive number of states. These effects are shown by numerical simulations in\na prototype lattice model and expose a different face of non-Hermitian skin\neffect, by disentangling it from the need for boundaries. We identify a\ntopological invariant responsible for the dislocation skin effect, which takes\nthe form of a ${\\mathbb Z}_2$ Hopf index that depends on the Burgers vector\ncharacterizing the dislocations. Remarkably, we find that this effect and its\ncorresponding signature for defects in Hermitian systems falls outside of the\nknown topological classification based on bulk-defect correspondence."
    },
    {
        "anchor": "Long exciton spin memory in coupled quantum wells: Spatially indirect excitons in a coupled quantum well structure were studied\nby means of polarization and time resolved photoluminescence. A strong degree\nof circular polarization (> 50%) in emission was achieved when the excitation\nenergy was tuned into resonance with the direct exciton state. The indirect\ntransition remained polarized several tens of nanoseconds after the pumping\nlaser pulse, demonstrating directly a very long relaxation time of exciton\nspin. The observed spin memory effect exceeds the radiative lifetime of the\nindirect excitons.",
        "positive": "Directionally asymmetric self-assembly of cadmium sulfide nanotubes\n  using porous alumina nanoreactors: Need for chemohydrodynamic instability at\n  the nanoscale: We explore nanoscale hydrodynamical effects on synthesis and self-assembly of\ncadmium sulfide nanotubes oriented along one direction. These nanotubes are\nsynthesized by horizontal capillary flow of two different chemical reagents\nfrom opposite directions through nanochannels of porous anodic alumina which\nare used primarily as nanoreactors. We show that uneven flow of different\nchemical precursors is responsible for directionally asymmetric growth of these\nnanotubes. On the basis of structural observations using scanning electron\nmicroscopy, we argue that chemohydrodynamic convective interfacial instability\nof multicomponent liquid-liquid reactive interface is necessary for sustained\nnucleation of these CdS nanotubes at the edges of these porous nanochannels\nover several hours. However, our estimates clearly suggest that classical\nhydrodynamics cannot account for the occurrence of such instabilities at these\nsmall length scales. Therefore, we present a case which necessitates further\ninvestigation and understanding of chemohydrodynamic fluid flow through\nnanoconfined channels in order to explain the occurrence of such interfacial\ninstabilities at nanometer length scales."
    },
    {
        "anchor": "Non-Generic Dispersion of Excitons in the Bulk of WSe$_2$: We combine electron energy-loss spectroscopy (EELS) and density functional\ntheory (DFT) calculations to study the dispersion and effective mass of\nexcitons in the bulk of WSe$_2$. Our EELS data suggest substantial deviations\nfrom the generic quadratic momentum dependence along the $\\Gamma K$-direction.\nFrom the DFT-derived Kohn-Sham states we deduce the EELS response without the\ninclusion of particle-hole attraction to study the possible role of the\nsingle-particle band structure on the exciton behavior. Based on this analysis\nwe argue in favor of a strongly momentum dependent particle-hole interaction in\nWSe$_2$ and other group VI-transition-metal dichalcogenides.",
        "positive": "Energy Levels in Spheroidal Quantum Dot: The effect of non-sphericity of the quantum dot on the eigenvalues and\neigenfunctions has been investigated for the case of both the finite and\ninfinite barrier. The ground and excited state energies have been calculated\nfor prolate and oblate spheroids as a function of eccentricity of the spheroid.\nThe analytic wavefunctions giving the admixture of higher angular momentum\nstates have been obtained as a function of eccentricity."
    },
    {
        "anchor": "Bounds on quantum confinement effects in metal nanoparticles: Quantum size effects on the permittivity of metal nanoparticles are\ninvestigated using the quantum box model. Explicit upper and lower bounds are\nderived for the permittivity and relaxation rates due to quantum confinement\neffects. These bounds are verified numerically, and the size-dependence and\nfrequency-dependence of the empirical Drude size parameter is extracted from\nthe model. Results suggest that the common practice of empirically modifying\nthe dielectric function can lead to inaccurate predictions for highly uniform\ndistributions of finite-sized particles.",
        "positive": "Effect of Coulomb scattering on graphene conductivity: The effect of Coulomb scattering on graphene conductivity in field effect\ntransistor structures is discussed. Inter-particle scattering\n(electron-electron, hole-hole, and electron-hole) and scattering on charged\ndefects are taken into account in a wide range of gate voltages. It is shown\nthat an intrinsic conductivity of graphene (purely ambipolar system where both\nelectron and hole densities exactly coincide) is defined by strong\nelectron-hole scattering. It has a universal value independent of temperature.\nWe give an explicit derivation based on scaling theory. When there is even a\nsmall discrepancy in electron and hole densities caused by applied gate voltage\nthe conductivity is determined by both strong electron-hole scattering and weak\nexternal scattering: on defects or phonons. We suggest that a density of\ncharged defects (occupancy of defects) depends on Fermi energy to explain a\nsub-linear dependence of conductivity on a fairly high gate voltage observed in\nexperiments. We also eliminate contradictions between experimental data\nobtained in deposited and suspended graphene structures regarding graphene\nconductivity."
    },
    {
        "anchor": "Correlative Microscopy of Morphology and Luminescence of Cu porphyrin\n  aggregates: Transfer of energy and information through molecule aggregates requires as\none important building block anisotropic, cable-like structures. Knowledge on\nthe spatial correlation of luminescence and morphology represents a\nprerequisite in the understanding of internal processes and will be important\nfor architecting suitable landscapes. In this context we study the morphology,\nfluorescence and phosphorescence of molecule aggregate structures on surfaces\nin a spatially correlative way. We consider as two morphologies, lengthy\nstrands and isotropic islands. It turns out that phosphorescence is quite\nstrong compared to fluorescence and the spatial variation of the observed\nintensities is largely in line with the amount of dye. However in proportion,\nthe strands exhibit more fluorescence than the isotropic islands suggesting\nweaker non-radiative channels. The ratio fluorescence to phosphorescence\nappears to be correlated with the degree of aggregation or internal order. The\nheights at which luminescence saturates is explained in the context of\nattenuation and emission multireflection, inside the dye. This is supported by\ncorrelative photoemission electron microscopy which is more sensitive to the\nsurface region. The lengthy structures exhibit a pronounced polarization\ndependence of the luminescence with a relative dichroism up to about 60%,\nrevealing substantial perpendicular orientation preference of the molecules\nwith respect to the substrate and parallel with respect to the strands.",
        "positive": "Straining the Identity of Majorana Fermions: We propose an experimental setup of an interferometer for the observation of\nneutral Majorana fermions on topological insulator - superconductor -\nferromagnet junctions. We show that the extended lattice defects naturally\npresent in materials, dislocations, induce spin currents on the edges while\nkeeping the bulk time-reversal symmetry intact. We propose a simple two\nterminal conductance measurement in an interferometer formed by two edge point\ncontacts, which reveals the nature of Majorana states through the effect of\ndislocations. The zero temperature magneto-conductance changes from even\noscillations with period phi/2 (phi is the flux quantum hc/e) to odd\noscillations with period phi, when non-trivial dislocations are present and the\nMajorana states are sufficiently strongly coupled. Additionally, the\nconductance acquires a notable asymmetry as a function of the incident electron\nenergy, due to the topological influence of the dislocations, while resonances\nappear at the coupling energy of Majorana states."
    },
    {
        "anchor": "Transport properties of a molecule embedded in an Aharonov-Bohm\n  interferometer: We theoretically investigate the transport properties of a molecule embedded\nin one arm of a mesoscopic Aharonov-Bohm interferometer. Due to the presence of\nphonons the molecule level position ($\\epsilon_d$) and the electron-electron\ninteraction ($U$) undergo a \\emph{polaronic shift} which affects dramatically\nthe electronic transport through the molecular junction. When the\nelectron-phonon interaction is weak the linear conductance presents Fano-line\nshapes as long as the direct channel between the electrodes is opened. The\nobserved Fano resonances in the linear conductance are originated from the\ninterference between the spin Kondo state and the direct path. For strong\nenough electron-phonon interaction, the electron-electron interaction is\nrenormalized towards negative values, {\\it i.e.} becomes effectively\nattractive. This scenario favors fluctuations between the empty and doubly\noccupied charge states and therefore promotes a charge Kondo effect. However,\nthe direct path between the contacts breaks the electron-hole symmetry which\ncan efficiently suppress this charge Kondo effect. Nevertheless, we show that a\nproper tuning of the gate voltage is able to revive the Kondo resonance. Our\nresults are obtained by using the Numerical Renormalization approximation to\ncompute the electronic spectral function and the linear conductance.",
        "positive": "Landau-Zener transition between two levels coupled to continuum: For a Landau-Zener transition in a two-level system, the probability for a\nparticle, initially in the first level, {\\em i}, to survive the transition and\nto remain in the first level, depends exponentially on the square of the tunnel\nmatrix element between the two levels. This result remains valid when the\nsecond level, {\\em f}, is broadened due to e.g. coupling to continuum [V. M.\nAkulin and W. P. Schleicht, Phys. Rev. A {\\bf 46}, 4110 (1992)]. If the level,\n{\\em i}, is also coupled to continuum, albeit much weaker than the level {\\em\nf}, a particle, upon surviving the transition, will eventually escape. However,\nfor shorter times, the probability to find the particle in the level {\\em i}\nafter crossing {\\em f} is {\\em enhanced} due to the coupling to continuum.\nThis, as shown in the present paper, is the result of a second-order process,\nwhich is an {\\em additional coupling between the levels}. The underlying\nmechanism of this additional coupling is virtual tunneling from {\\em i} into\ncontinuum followed by tunneling back into {\\em f}."
    },
    {
        "anchor": "Giant radiative thermal rectification using an intrinsic semiconductor\n  film: Rectification of heat flow via a thermal diode is not only of fundamental\ninterest, but can also enable a range of novel applications in thermal\nmanagement and energy conversion. However, despite decades of extensive\nresearch, large rectification ratios of practical importance have yet to be\ndemonstrated. Here, we theoretically achieve giant rectification ratios (3 to\nalmost 5 orders of magnitude) by leveraging near-field radiative thermal\ntransport between two parallel planes. Guided by a rational design approach\ncentering on the electromagnetic local density of states (LDOS), we employ a\nthin film of an intrinsic semiconductor-such as silicon-as one terminal of our\nradiative thermal diodes, which provides the necessary nonlinearity and a\nsubstantial LDOS contrast as the temperature bias is flipped. For the other\nterminal, we explore two kinds of materials which either serve as a narrowband\nor a broadband filter, both capable of converting the large LDOS contrast into\ngiant thermal rectification. We further consider representative multilayer\nconfigurations in order to block backside radiation and improve mechanical\nstability. All the diodes perform well over a wide range of film thicknesses,\ngap sizes, and temperatures. Our work offers an opportunity for realizing\nthermal diodes with unprecedented rectification ratios.",
        "positive": "`Deterministic' quantum plasmonics: We demonstrate `deterministic' launching of propagative quantum\nsurface-plasmon polaritons at freely chosen positions on gold plasmonic\nreceptacles. This is achieved by using as plasmon launcher a near-field\nscanning optical source made of a diamond nanocrystal with two Nitrogen-Vacancy\ncolor-center occupancy. Our demonstration relies on leakage-radiation\nmicroscopy of a thin homogeneous gold film and on near-field optical microscopy\nof a nanostructured thick gold film. Our work paves the way to future\nfundamental studies and applications in quantum plasmonics that require an\naccurate positioning of single-plasmon sources and may open a new branch in\nplasmonics and nanophotonics, namely scanning quantum plasmonics."
    },
    {
        "anchor": "Graphene-mediated exchange coupling between cobaltocene and magnetic\n  substrates: Using first-principles calculations we demonstrate sizable exchange coupling\nbetween a magnetic molecule and a magnetic substrate via a graphene layer. As a\nmodel system we consider cobaltocene (CoCp$_2$) adsorbed on graphene deposited\non Ni(111). We find that the magnetic coupling between the molecule and the\nsubstrate is antiferromagnetic and varies considerably depending on the\nmolecule structure, the adsorption geometry, and the stacking of graphene on\nNi(111). We show how this coupling can be tuned by intercalating a magnetic\nmonolayer, e.g. Fe or Co, between graphene and Ni(111). We identify the leading\nmechanism responsible for the coupling to be the spatial and energy matching of\nthe frontier orbitals of CoCp$_2$ and graphene close to the Fermi level, and we\ndemonstrate the role of graphene as an electronic decoupling layer, yet\nallowing spin communication between molecule and substrate.",
        "positive": "Tailoring and enhancing spontaneous two-photon emission processes using\n  resonant plasmonic nanostructures: The rate of spontaneous emission is known to depend on the environment of a\nlight source, and the enhancement of one-photon emission in a resonant cavity\nis known as the Purcell effect. Here we develop a theory of spontaneous\ntwo-photon emission for a general electromagnetic environment including\ninhomogeneous dispersive and absorptive media. This theory is used to evaluate\nthe two-photon Purcell enhancement in the vicinity of metallic nanoparticles\nand it is demonstrated that the surface plasmon resonances supported by these\nparticles can enhance the emission rate by more than two orders of magnitude.\nThe control over two-photon Purcell enhancement given by tailored\nnanostructured environments could provide an emitter with any desired spectral\nresponse and may serve as an ultimate route for designing light sources with\nnovel properties."
    },
    {
        "anchor": "Heat transfer at the van der Waals interface between graphene and NbSe2: Graphene has been widely used to construct low-resistance van der Waals (vdW)\ncontacts to other two-dimensional (2D) materials. However, a rise of electron\ntemperature of the graphene under a current flow has not been seriously\nconsidered in many applications. Owing to its small electronic heat capacity\nand electron-phonon coupling, electron temperature of the graphene can be\nincreased easily by the application of current. The heat generated within the\ngraphene is transferred to the contacted 2D materials through the vdW interface\nand potentially influences their properties. Here, we compare the\nsuperconducting critical currents of an NbSe2 flake for two different methods\nof current application: with a Au/Ti electrode fabricated by thermal\nevaporation and with a graphene electrode contacted to the NbSe2 flake through\na vdW interface. The influence of the heat transfer from the graphene to NbSe2\nis detected through the change of the superconductivity of NbSe2. We found that\nthe critical current of NbSe2 significantly reduces when the current is applied\nwith the graphene electrode compared to that from the conventional Au/Ti\nelectrode. Further, since the electron heating in graphene exhibits ambipolar\nback-gate modulation, we demonstrate the electric field modulation of the\ncritical current in NbSe2 when the current is applied with graphene electrode.\nThese results are attributed to the significant heat transfer from the graphene\nelectrode to NbSe2 through vdW interface.",
        "positive": "Deflection of (anti)ferromagnetic skyrmions at heterochiral interfaces: Devising magnetic nanostructures with spatially heterogeneous\nDzyaloshinskii-Moriya interaction (DMI) is a promising pathway towards advanced\nconfinement and control of magnetic skyrmions in potential devices. Here we\ndiscuss theoretically how a skyrmion interacts with a heterochiral interface\nusing micromagnetic simulations and analytic arguments. We show that a\nheterochiral interface deflects the trajectory of ferromagnetic (FM) skyrmions,\nand that the extent of such deflection is tuned by the applied spin-polarized\ncurrent and the difference in DMI across the interface. Further, we show that\nthis deflection is characteristic for the FM skyrmion, and is completely absent\nin the antiferromagnetic (AFM) case. In turn, we reveal that the AFM skyrmion\nachieves much higher velocities than its FM counterpart, yet experiences far\nstronger confinement in nanoengineered heterochiral tracks, which reinforces\nAFM skyrmions as a favorable choice for skyrmion-based devices."
    },
    {
        "anchor": "Valley polarized quantum Hall effect and topological insulator phase\n  transitions in silicene: Silicene is a buckled monolayer of silicon. Its electronic properties are\ndistinct from both the conventional two dimensional electron gas and the famous\ngraphene due to strong spin orbit interaction and the buckled structure.\nSilicene has the potential to overcome limitations encountered for graphene, in\nparticular the zero band gap and weak spin orbit interaction. We find for\nsilicene a valley polarized quantum Hall effect and topological insulator phase\ntransitions. We use the Kubo formalism to discuss the Hall conductivity and\naddress the longitudinal conductivity for elastic impurity scattering in the\nfirst Born approximation. We show that the combination of an electric field\nwith intrinsic spin orbit interaction leads to quantum phase transitions at the\ncharge neutrality point. This provides a tool to experimentally tune the\ntopological state of silicene. In contrast to graphene and other conventional\ntopological insulators, the effects in silicene are experimentally accessible.\nTherefore, silicene constitutes a model system for exploring the spin and\nvalley physics not accessible in graphene due to the small spin orbit\ninteraction.",
        "positive": "Pulse-width modulated oscillations in a nonlinear resonator under\n  two-tone driving as a means for MEMS sensor readout: A MEMS Duffing resonator is driven by two adjacent frequency tones into the\nnonlinear regime. We show that if the two-tone drive is applied at a frequency\nwhere a bistable response of the nonlinear oscillator exists, then the system\noutput will be modulated by a relaxation cycle caused by periodically jumping\nbetween the two solution-branches of the bistable response. Although the jumps\nare caused by the beating of the drives, the existence and period of this\nrelaxation or hysteresis cycle is not solely dictated by the beat frequency\nbetween the two driving tones, but also by their amplitude and detuning with\nrespect to the device resonance frequency. We equally demonstrate how the\nperiod of the cycles can be tuned via added tension in the device and how these\noscillations can be used as a means of sensitive pulse-width modulated (PWM)\nreadout of MEMS sensors."
    },
    {
        "anchor": "Magnetoplasmons and SU(4) symmetry in graphene: We study magnetoplasmons or neutral collective excitations of graphene in a\nstrong perpendicular magnetic field, which can be modelled as bound\nelectron-hole pairs. The SU(4) symmetry of graphene arising from spin and\nvalley pseudospin degrees of freedom is explored using Young diagrams to\ncorrectly predict the degeneracies of these excitations. The multiplet\nstructure of the states is identical to that of mesons composed of first and\nsecond generation quarks.",
        "positive": "Proximity-enhanced valley Zeeman splitting at the WS$_2$/graphene\n  interface: The valley Zeeman physics of excitons in monolayer transition metal\ndichalcogenides provides valuable insight into the spin and orbital degrees of\nfreedom inherent to these materials. Being atomically-thin materials, these\ndegrees of freedom can be influenced by the presence of adjacent layers, due to\nproximity interactions that arise from wave function overlap across the 2D\ninterface. Here, we report 60 T magnetoreflection spectroscopy of the A- and B-\nexcitons in monolayer WS$_2$, systematically encapsulated in monolayer\ngraphene. While the observed variations of the valley Zeeman effect for the A-\nexciton are qualitatively in accord with expectations from the bandgap\nreduction and modification of the exciton binding energy due to the\ngraphene-induced dielectric screening, the valley Zeeman effect for the B-\nexciton behaves markedly different. We investigate prototypical WS$_2$/graphene\nstacks employing first-principles calculations and find that the lower\nconduction band of WS$_2$ at the $K/K'$ valleys (the $CB^-$ band) is strongly\ninfluenced by the graphene layer on the orbital level. This leads to variations\nin the valley Zeeman physics of the B- exciton, consistent with the\nexperimental observations. Our detailed microscopic analysis reveals that the\nconduction band at the $Q$ point of WS$_2$ mediates the coupling between $CB^-$\nand graphene due to resonant energy conditions and strong coupling to the Dirac\ncone. Our results therefore expand the consequences of proximity effects in\nmultilayer semiconductor stacks, showing that wave function hybridization can\nbe a multi-step process with different bands mediating the interlayer\ninteractions. Such effects can be exploited to resonantly engineer the\nspin-valley degrees of freedom in van der Waals and moir\\'e heterostructures."
    },
    {
        "anchor": "Multiple Silicon Atom Artificial Molecules: We present linear ensembles of dangling bond chains on a hydrogen terminated\nSi(100) surface, patterned in the closest spaced arrangement allowed by the\nsurface lattice. Local density of states maps over a range of voltages\nextending spatially over the close-coupled entities reveal a rich energetic and\nspatial variation of electronic states. These artificial molecules exhibit\ncollective electronic states resulting from covalent interaction of the\nconstituent atoms. A pronounced electrostatic perturbation of dangling bond\nchain structure is induced by close placement of a negatively dangling bond.\nThe electronic changes so induced are entirely removed, paradoxically, by\naddition of a second dangling bond.",
        "positive": "Anomalous Hall effect in 2D Dirac materials: We present a unified theory of charge carrier transport in 2D Dirac systems\nwith broken mirror inversion and time-reversal symmetries (e.g., as realized in\nferromagnetic graphene). We find that the entanglement between spin and\npseudospin SU(2) degrees of freedom stemming from spin-orbit effects leads to a\ndistinctive gate voltage dependence (change of sign) of the anomalous Hall\nconductivity approaching the topological gap, which remains robust against\nimpurity scattering and thus is a smoking gun for magnetized 2D Dirac fermions.\nFurthermore, we unveil a robust skew scattering mechanism, modulated by the\nspin texture of the energy bands, which causes a net spin accumulation at the\nsample boundaries even for spin-transparent disorder. The newly unveiled\nextrinsic spin Hall effect is readily tunable by a gate voltage and opens novel\nopportunities for the control of spin currents in 2D ferromagnetic materials."
    },
    {
        "anchor": "Enhanced quantum yields and efficiency in a quantum dot photocell\n  modeled by a multi-level system: To absorb the photons below the band-gap energy effectively, we proposed a\nquantum dot (QD) photocell modeled by multi-level system for the quantum yields\nand photo-to-charge efficiency limits. The theoretical results show the quantum\nyields are enhanced as compared to the single band-gap solar cell, and the\nphoto-to-charge efficiencies are larger than Shockley and Queisser efficiency\nin the same absorbed spectrum. What's more, at the room temperature the\nefficiency limits are well beyond 63% achieved by Luque and Marti\n(Ref\\cite{26}) due to absorbing the low-energy photons via two sub-bands in\nthis proposed photocell system. The achievements may reveal a novel theoretical\napproach to enhance the QD photocell performance modeled a multi-level\nabsorbing photons system.",
        "positive": "Strong Electron-Electron Interactions of a Tomonaga--Luttinger Liquid\n  Observed in InAs Quantum Wires: We report strong electron-electron interactions in quantum wires etched from\nan InAs quantum well, a material known to have strong spin-orbit interactions.\nWe find that the current through the wires as a function of the bias voltage\nand temperature follows the universal scaling behavior of a Tomonaga--Luttinger\nliquid. Using a universal scaling formula, we extract the interaction parameter\nand find strong electron-electron interactions, increasing as the wires become\nmore depleted. We establish theoretically that spin-orbit interactions cause\nonly minor modifications of the interaction parameter in this regime,\nindicating that genuinely strong electron-electron interactions are indeed\nachieved in the device. Our results suggest that etched InAs wires provide a\nplatform with both strong electron-electron and strong spin-orbit interactions."
    },
    {
        "anchor": "Anisotropic Magnetoresistance components in (Ga,Mn)As: Our experimental and theoretical study of the non-crystalline and crystalline\ncomponents of the anisotropic magnetoresistance (AMR) in (Ga,Mn)As is aimed at\nexploring the basic physical aspects of this relativistic transport effect. The\nnon-crystalline AMR reflects anisotropic lifetimes of the holes due to\npolarized Mn impurities while the crystalline AMR is associated with valence\nband warping. We find that the sign of the non-crystalline AMR is determined by\nthe form of spin-orbit coupling in the host band and by the relative strengths\nof the non-magnetic and magnetic contributions to the impurity potential. We\ndevelop experimental methods directly yielding the non-crystalline and\ncrystalline AMR components which are then independently analyzed. We report the\nobservation of an AMR dominated by a large uniaxial crystalline component and\nshow that AMR can be modified by local strain relaxation. We discuss generic\nimplications of our experimental and theoretical findings including predictions\nfor non-crystalline AMR sign reversals in dilute moment systems.",
        "positive": "Exciton Condensation and Perfect Coulomb Drag: Coulomb drag is a process whereby the repulsive interactions between\nelectrons in spatially separated conductors enable a current flowing in one of\nthe conductors to induce a voltage drop in the other. If the second conductor\nis part of a closed circuit, a net current will flow in that circuit. The drag\ncurrent is typically much smaller than the drive current owing to the heavy\nscreening of the Coulomb interaction. There are, however, rare situations in\nwhich strong electronic correlations exist between the two conductors. For\nexample, bilayer two-dimensional electron systems can support an exciton\ncondensate consisting of electrons in one layer tightly bound to holes in the\nother. One thus expects \"perfect\" drag; a transport current of electrons driven\nthrough one layer is accompanied by an equal one of holes in the other. (The\nelectrical currents are therefore opposite in sign.) Here we demonstrate just\nthis effect, taking care to ensure that the electron-hole pairs dominate the\ntransport and that tunneling of charge between the layers is negligible."
    },
    {
        "anchor": "Magnetization Dynamics of Nanoscale Magnetic Materials: A Perspective: Nanomagnets form the building blocks for a gamut of miniaturized\nenergy-efficient devices including data storage, memory, wave-based computing,\nsensors and biomedical devices. They also offer a span of exotic phenomena and\nstern challenges. The progress in the magnetization dynamics of single\nnanomagnets and one- and two-dimensional arrays of nanostructures in the form\nof dots, antidots, nanoparticles, binary and bicomponent structures and\npatterned multilayers have been presented. Progress in unconventional and new\nstructures like artificial spin ice and three-dimensional nanomagnets and spin\ntextures like domain walls, vortex and skyrmions have been presented.\nFurthermore, a huge variety of new topics in the magnetization dynamics of\nmagnetic nanostructures are rapidly emerging. An overview of the steadily\nevolving topics like spatio-temporal imaging of fast dynamics of\nnanostructures, dynamics of spin textures, artificial spin ice have been\ndiscussed. In addition, dynamics of contemporary and newly transpired magnetic\narchitectures such as nanomagnet arrays with complex basis and symmetry,\nmagnonic quasicrystals, fractals, defect structures, novel three-dimensional\nstructures have been introduced. Effects of various spin-orbit coupling and\nensuing spin textures as well as quantum hybrid systems comprising of\nmagnon-photon, magnon-phonon and magnon-magnon coupling, antiferromagnetic\nnanostructures are rapidly growing and are expected to dominate this research\nfield in the coming years. Finally, associated topics like nutation dynamics\nand nanomagnet antenna are briefly discussed. Despite showing a great progress,\nonly a small fraction of nanomagnetism and its ancillary topics have been\nexplored so far and huge efforts are envisaged in this evergrowing research\narea in the generations to come.",
        "positive": "Distance dependence of the energy transfer mechanism in WS$_2$-graphene\n  heterostructures: We report on the mechanism of energy transfer in van der Waals\nheterostructures of the two-dimensional semiconductor WS$_2$ and graphene with\nvarying interlayer distances, achieved through spacer layers of hexagonal boron\nnitride (hBN). We record photoluminescence and reflection spectra at interlayer\ndistances between 0.5 nm and 5.8 nm (0-16 hBN layers). We find that the energy\ntransfer is dominated by states outside the light cone, indicative of a\nF\\\"orster transfer process, with an additional contribution from a Dexter\nprocess at 0.5 nm interlayer distance. We find that the measured dependence of\nthe luminescence intensity on interlayer distances above 1 nm can be\nquantitatively described using recently reported values of the F\\\"orster\ntransfer rates of thermalized charge carriers. At smaller interlayer distances,\nthe experimentally observed transfer rates exceed the predictions and\nfurthermore depend on excess energy as well as on excitation density. Since the\ntransfer probability of the F\\\"orster mechanism depends on the momentum of\nelectron-hole pairs, we conclude that at these distances, the transfer is\ndriven by non-thermalized charge carrier distributions."
    },
    {
        "anchor": "Absolute Negative Conductivity and Spontaneous Current Generation in\n  Semiconductor Superlattices with Hot Electrons: We study electron transport through a semiconductor superlattice subject to\nan electric field parallel to and a magnetic field perpendicular to the growth\naxis. Using a single miniband, semiclassical balance equation model with both\nelastic and inelastic scattering, we find that (1) the current-voltage\ncharacteristic becomes multistable in a large magnetic field; and (2) ``hot''\nelectrons display novel features in their current-voltage characteristics,\nincluding absolute negative conductivity (ANC) and, for sufficiently strong\nmagnetic fields, a spontaneous dc current at zero bias. We discuss possible\nexperimental situations providing the necessary hot electrons to observe the\npredicted ANC and spontaneous dc current generation.",
        "positive": "Microscopic theory on magnetic-field-tuned sweet spot of exchange\n  interactions in multielectron quantum-dot systems: The exchange interaction in a singlet-triplet qubit defined by two-electron\nstates in the double-quantum-dot system (\"two-electron singlet-triplet qubit\")\ntypically varies monotonically with the exchange interaction and thus carries\nno sweet spot. Here we study a singlet-triplet qubit defined by four-electron\nstates in the double-quantum-dot system (\"four-electron singlet-triplet\nqubit\"). We demonstrate, using configuration-interaction calculations, that in\nthe four-electron singlet-triplet qubit the exchange energy as a function of\ndetuning can be non-monotonic, suggesting existence of sweet spots. We further\nshow that the tuning of the sweet spot and the corresponding exchange energy by\nperpendicular magnetic field can be related to the variation of orbital\nsplitting. Our results suggest that a singlet-triplet qubit with more than two\nelectrons can have advantages in the realization of quantum computing."
    },
    {
        "anchor": "Magnetoresistance of a three-dimensional Dirac gas: We study the transversal magnetoconductivity and magnetoresistance of a\nmassive Dirac fermion gas. This can be used as a simple model for gapped Dirac\nmaterials. In the zero-mass limit, the case of gapless Dirac semimetals is also\nstudied. In the case of Weyl semimetals, to reproduce the nonsaturating linear\nmagnetoresistance seen in experiments, the use of screened charged impurities\nis inevitable. In this paper, these are included using the first Born\napproximation for the self-energy. The screening wave number is calculated\nusing the random phase approximation with the polarization function taking into\naccount the electron-electron interaction. The Hall conductivity is calculated\nanalytically in the case of no impurities and is shown to be perfectly\ninversely proportional to the magnetic field. Thus the magnetic field\ndependence of the magnetoresistance is mainly determined by $\\sigma_{xx}$. We\nshow that in the extreme quantum limit at very high magnetic fields the gapped\nDirac materials are expected to have $\\sigma_{xx}\\propto B^{-3}$ leading to\n$\\varrho_{xx}\\propto B^{-1}$, in contrast with the gapless case where\n$\\sigma_{xx}\\propto B^{-1}$ and $\\varrho_{xx}\\propto B$. At lower fields, we\nfind that the effect of the mass term is negligible and in the region of the\nShubnikov-de Haas oscillations the two systems behave almost identically. We\nsuggest a phenomenological scattering rate that is able to reproduce the linear\nbehavior at the oscillating region. We show that in the case of the scattering\nrate calculated using the Born approximation, the strength of the relative\npermittivity and the density of impurities affects the magnetic field\ndependence of the conductivity significantly.",
        "positive": "Electron spin polarization induced by spin Hall effect in semiconductors\n  with a linear in the momentum spin-orbit splitting of conduction band: It is shown that spin Hall effect creates uniform spin polarization of\nelectrons in semiconductor with a linear in the momentum spin splitting of\nconduction band. In turn, the profile of the non-uniform spin polarization\naccumulated at the edge of the sample oscillates in space even in the absence\nof an external magnetic field."
    },
    {
        "anchor": "Edge-state enhanced transport in a 2-dimensional quantum walk: Quantum walks on translation invariant regular graphs spread quadratically\nfaster than their classical counterparts. The same coherence that gives them\nthis quantum speedup inhibits, or even stops their spread in the presence of\ndisorder. We ask how to create an efficient transport channel from a fixed\nsource site (A) to fixed target site (B) in a disordered 2-dimensional\ndiscrete-time quantum walk by cutting some of the links. We show that the\nsomewhat counterintuitive strategy of cutting links along a single line\nconnecting A to B creates such a channel. The efficient transport along the cut\nis due to topologically protected chiral edge states, which exist even though\nthe bulk Chern number in this system vanishes. We give a realization of the\nwalk as a periodically driven lattice Hamiltonian, and identify the bulk\ntopological invariant responsible for the edge states as the quasienergy\nwinding of this Hamiltonian.",
        "positive": "Excitons and high-order optical transitions in individual carbon\n  nanotubes: We examine the excitonic nature of high-lying optical transitions in\nsingle-walled carbon nanotubes by means of Rayleigh scattering spectroscopy. A\ncareful analysis of the principal transitions of individual semiconducting and\nmetallic nanotubes reveals that in both cases the lineshape is consistent with\nan excitonic model, but not one of free-carriers. For semiconducting species,\nside-bands are observed at ~200 meV above the third and fourth optical\ntransitions. These features are ascribed to exciton-phonon bound states. Such\nside-bands are not apparent for metallic nanotubes,as expected from the reduced\nstrength of excitonic interactions in these systems."
    },
    {
        "anchor": "Many-Body perturbation theory calculations on circular quantum dots: The possibility to use perturbation theory to systematically improve\ncalculations on circular quantum dots is investigated. A few different starting\npoints, including Hartree-Fock, are tested and the importance of correla- tion\nis discussed. Quantum dots with up to 12 electrons are treated and the effects\nof an external magnetic field are examined. The sums over excited states are\ncarried out with a complete finite radial basis set obtained through the use of\nB splines. The calculated addition energy spectra are compared with experiments\nand the implications for the filling sequence of the third shell are discussed\nin detail.",
        "positive": "Computational Determination of the Electronic Structure for different\n  Graphene Quantum Dot geometries: The interaction between carbon nanostructures like quantum dots and radiation\ncan generate different effects inside the nanomaterial, with the use of\ncomputational methods such effects can be predicted and optimize the material\nallowing a desired output. In this work, a theoretical model for pristine\ngraphene quantum dots is studied, allowing to explain the shape and size\ndependence for the electronic properties and how the bandgap can be tuned with\nthe functionalization of the nanostructure at the edges."
    },
    {
        "anchor": "Exact transition probabilities for a linear sweep through a\n  Kramers-Kronig resonance: We consider a localized electronic spin controlled by a circularly polarized\noptical beam and an external magnetic field. When the frequency of the beam is\ntuned near an optical resonance with a continuum of higher energy states,\neffective magnetic fields are induced on the two-level system via the Inverse\nFaraday Effect. We explore the process in which the frequency of the beam is\nmade linearly time-dependent so that it sweeps through the optical resonance,\nstarting and ending at the values far away from it. In addition to changes of\nspin states, Kramers-Kronig relations guarantee that a localized electron can\nalso escape into a continuum of states. We argue that probabilities of\ntransitions between different possible electronic states after such a sweep of\nthe optical frequency can be found exactly regardless the shape of the\nresonance. We also discuss extension of our results to multistate systems.",
        "positive": "A low-disorder Metal-Oxide-Silicon double quantum dot: One of the biggest challenges impeding the progress of Metal-Oxide-Silicon\n(MOS) quantum dot devices is the presence of disorder at the Si/SiO$_2$\ninterface which interferes with controllably confining single and few\nelectrons. In this work we have engineered a low-disorder MOS quantum\ndouble-dot device with critical electron densities, i.e. the lowest electron\ndensity required to support a conducting pathway, approaching critical electron\ndensities reported in high quality Si/SiGe devices and commensurate with the\nlowest critical densities reported in any MOS device. Utilizing a nearby charge\nsensor, we show that the device can be tuned to the single-electron regime\nwhere charging energies of $\\approx$8 meV are measured in both dots, consistent\nwith the lithographic size of the dot. Probing a wide voltage range with our\nquantum dots and charge sensor, we detect three distinct electron traps,\ncorresponding to a defect density consistent with the ensemble measured\ncritical density. Low frequency charge noise measurements at 300 mK indicate a\n1/$f$ noise spectrum of 3.4 $\\mu$eV/Hz$^{1/2}$ at 1 Hz and magnetospectroscopy\nmeasurements yield a valley splitting of 110$\\pm$26 $\\mu$eV. This work\ndemonstrates that reproducible MOS spin qubits are feasible and represents a\nplatform for scaling to larger qubit systems in MOS."
    },
    {
        "anchor": "Transport properties of nano-devices: One-dimensional model study: A 1D model study of charge transport in nano-devices is made by comparing\nmulti-configuration time dependent Hartree-Fock and frozen core calculations.\nThe influence of exchange and Coulomb correlation on the tunneling current is\ndetermined. We identify the shape of the tunneling barrier and the resonance\nstructure of the nano-device as the two dominant parameters determining the\nelectron transport. Whereas the barrier shape determines the size of the\ntunneling current, the resonances determine the structure of the current.",
        "positive": "Sensing chiral magnetic noise via quantum impurity relaxometry: We present a theory for quantum impurity relaxometry of magnons in thin\nfilms, exhibiting quantitative agreement with recent experiments without\nneeding arbitrary scale factors used in theoretical models thus far. Our theory\nreveals that chiral coupling between prototypical spin>1/2 quantum impurities\nand magnons plays a central role in determining impurity relaxation, which is\nfurther corroborated by our experiments on nickel films interfaced with\nnitrogen-vacancy centers. Along with advancing magnonics and understanding\ndecoherence in hybrid quantum platforms with magnets, the ability of a quantum\nimpurity spin to sense chiral magnetic noise presents an opportunity to probe\nchiral phenomena in condensed matter."
    },
    {
        "anchor": "Supplementary Information: Quantum phase transition in a single-molecule\n  quantum dot: Quantum criticality is the intriguing possibility offered by the laws of\nquantum mechanics when the wave function of a many-particle physical system is\nforced to evolve continuously between two distinct, competing ground states.\nThis phenomenon, often related to a zero-temperature magnetic phase transition,\ncan be observed in several strongly correlated materials such as heavy fermion\ncompounds or possibly high-temperature superconductors, and is believed to\ngovern many of their fascinating, yet still unexplained properties. In contrast\nto these bulk materials with very complex electronic structure, artificial\nnanoscale devices could offer a new and simpler vista to the comprehension of\nquantum phase transitions. This long-sought possibility is demonstrated by our\nwork in a fullerene molecular junction, where gate voltage induces a crossing\nof singlet and triplet spin states at zero magnetic field. Electronic tunneling\nfrom metallic contacts into the $\\rm{C_{60}}$ quantum dot provides here the\nnecessary many-body correlations to observe a true quantum critical behavior.",
        "positive": "Contacts for organic switches with carbon-nanotube leads: Molecular devices, as future electronics, seek low-resistivity contacts for\nthe energy saving. At the same time, the contacts should intensify desired\nproperties of tailored electronic elements. In this work, we focus our\nattention on two classes of organic switches connected to carbon-nanotube leads\nand operating due to photo- or field-induced proton transfer (PT) process. By\nmeans of the first-principles atomistic simulations of the ballistic\nconductance, we search for atomic contacts which strengthen diversity of the\ntwo swapped I-V characteristics between two tautomers of a given molecular\nsystem. We emphasize, that the low-resistive character of the contacts is not\nnecessarily in accordance with the switching properties. Very often, the\nhigher-current flow makes it more difficult to distinguish between the logic\nstates of the molecular device. Instead, the resistive contacts multiply a\ncurrent gear at the tautomeric transition to a larger extent. The low- and\nhigh-bias work regimes set additional conditions, which are fulfilled by\ndifferent contacts. In some cases, the peroxide contacts or the direct\nconnection to the tube perform better than the popular sulfur contact.\nAdditionally, we find that the switching-bias value is not an inherent property\nof the conducting molecule, but it strongly depends on the chosen contacts."
    },
    {
        "anchor": "Spin transport and tunable Gilbert damping in a single-molecule magnet\n  junction: We study time-dependent electronic and spin transport through an electronic\nlevel connected to two leads and coupled with a single-molecule magnet via\nexchange interaction. The molecular spin is treated as a classical variable and\nprecesses around an external magnetic field. We derive expressions for charge\nand spin currents by means of the Keldysh non-equilibrium Green's functions\ntechnique in linear order with respect to the time-dependent magnetic field\ncreated by this precession. The coupling between the electronic spins and the\nmagnetization dynamics of the molecule creates inelastic tunneling processes\nwhich contribute to the spin currents. The inelastic spin currents, in turn,\ngenerate a spin-transfer torque acting on the molecular spin. This back-action\nincludes a contribution to the Gilbert damping and a modification of the\nprecession frequency. The Gilbert damping coefficient can be controlled by the\nbias and gate voltages or via the external magnetic field and has a\nnon-monotonic dependence on the tunneling rates.",
        "positive": "Heat Transport in Mesoscopic Systems: Phonon heat transport in mesoscopic systems is investigated using methods\nanalogous to the Landauer description of electrical conductance. A \"universal\nheat conductance\" expression that depends on the properties of the conducting\npathway only through the mode cutoff frequencies is derived. Corrections due to\nreflections at the junction between the thermal body and the conducting bridge\nare found to be small except at very low temperatures where only the lowest few\nbridge modes are excited. Various non-equilibrium phonon distributions are\nstudied: a narrow band distribution leads to clear steps in the cooling curve,\nanalogous to the quantized resistance values in narrow wires, but a thermal\ndistribution is too broad to show such features."
    },
    {
        "anchor": "Probing the band structure of quadri-layer graphene with magneto-phonon\n  resonance: We show how the magneto-phonon resonance, particularly pronounced in sp2\ncarbon allotropes, can be used as a tool to probe the band structure of\nmultilayer graphene specimens. Even when electronic excitations cannot be\ndirectly observed, their coupling to the E2g phonon leads to pronounced\noscillations of the phonon feature observed through Raman scattering\nexperiments with multiple periods and amplitudes detemined by the electronic\nexcitation spectrum. Such experiment and analysis have been performed up to 28T\non an exfoliated 4-layer graphene specimen deposited on SiO2, and the observed\noscillations correspond to the specific AB stacked 4-layer graphene electronic\nexcitation spectrum.",
        "positive": "Poiseuille flow of liquid methane in nanoscopic graphite channels by\n  molecular dynamics simulation: MD simulations of methane confined between graphite walls with up to\n4,800,000 interaction sites, i.e., carbon atoms and methane molecules, are\nconducted, where the channel width is varied to include both the\nboundary-dominated regime and the transition to the continuum regime. This\nproves that MD can be used today to cover the entire range of characteristic\nlengths for which continuum methods fail."
    },
    {
        "anchor": "Signatures of two- and three-dimensional semimetals from circular\n  dichroism: Topological invariants are crucial quantities for classifying materials with\ntopological phases. Hence, their connections with experimentally measurable\nquantities are extremely important. In this context, circular dichroism (CD)\nprovides a protocol to detect the Chern number $\\mathcal{C}_0$ of the lowest\nenergy Bloch band (LBB) of a semimetal. This hinges on the unequal depletion\nrates of the Bloch electrons from a filled LBB, under the action of a\ntime-periodic circular drive, depending on the chirality of the polarization.\nAccording to the dimensionality of the system (i.e., whether it is two- or\nthree-dimensional), the integrated differential rate for depletion has to be\nformulated a bit differently in order to relate it to $\\mathcal{C}_0$. Our aim\nis to capture the nature of the CD response for semimetals with anisotropic\nband dispersions. We show that while the quantization of the CD response for\nthe three-dimensional cases is strongly sensitive to anisotropy, the\ntwo-dimensional counterparts show a perfectly quantized response.",
        "positive": "sin(2 phi) current-phase relation in SFS junctions with decoherence in\n  the ferromagnet: We propose a theoretical description of the sin(2 phi) current-phase relation\nin SFS junctions at the 0-$\\pi$ cross-over obtained in recent experiments by\nSellier et al. [Phys. Rev. Lett. 92, 257005 (2004)] where it was suggested that\na strong decoherence in the magnetic alloy can explain the magnitude of the\nresidual supercurrent at the 0-pi cross-over. To describe the interplay between\ndecoherence and elastic scattering in the ferromagnet we use an analogy with\ncrossed Andreev reflection in the presence of disorder. The supercurrent as a\nfunction of the length R of the ferromagnet decays exponentially over a length\nxi, larger than the elastic scattering length $l_d$ in the absence of\ndecoherence, and smaller than the coherence length $l_\\phi$ in the absence of\nelastic scattering on impurities. The best fit leads to $\\xi \\simeq\n\\xi_h^{({\\rm diff})}/3$, where $\\xi_h^{({\\rm diff})}$ is exchange length of the\ndiffusive system without decoherence (also equal to $\\xi$ in the absence of\ndecoherence). The fit of experiments works well for the amplitude of both the\nsin(phi) and sin(2 phi) harmonics."
    },
    {
        "anchor": "Microwave-induced magnetotransport phenomena in two-dimensional electron\n  systems: Importance of electrodynamic effects: We discuss possible origins of recently discovered microwave induced\nphotoresistance oscillations in very-high-electron-mobility two-dimensional\nelectron systems. We show that electrodynamic effects -- the radiative decay,\nplasma oscillations, and retardation effects, -- are important under the\nexperimental conditions, and that their inclusion in the theory is essential\nfor understanding the discussed and related microwave induced magnetotransport\nphenomena.",
        "positive": "Photoconductivity in Ac-driven lateral superlattice in the presence of a\n  magnetic field: In this work we present a model for the photoconductivity of two-dimensional\nelectron system in a perpendicular homogeneous magnetic field, a weak lateral\nsuperlattice, and exposed to millimeter irradiation. The model includes the\nmicrowave and Landau contributions in a non-perturbative exact way, the\nperiodic potential is treated perturbatively. The Landau-Floquet states provide\na convenient base with respect to which the lattice potential becomes\ntime-dependent, inducing transitions between the Landau-Floquet levels. Based\non this formalism, we provide a Kubo-like formula that takes into account the\noscillatory Floquet structure of the problem. The total conductivity exhibits\nstrong oscillations, determined by $\\epsilon = \\omega / \\omega_c$ with $\\omega$\nthe radiation frequency and $\\omega_c$ the cyclotron frequency. The\noscillations follow a pattern with minima centered at $\\omega/\\omega_c =j +\n{1/2} (l-1) + \\delta $, and maxima centered at $\\omega/\\omega_c =j + {1/2}\n(l-1) - \\delta $, where $j=1,2,3.......$, $\\delta$ is a constant phase shift\nand $l$ is the dominant multipole contribution. Negative conductance states\ndevelop as the electron mobility and the intensity of the microwave power are\nincreased. It is proposed that, depending on the geometry, negative conductance\nsates or negative resistance states may be observed in lateral superlattices\nfabricated in $GaAs/AlGa As$ heterostructures."
    },
    {
        "anchor": "Epitaxial Indium on PbTe Nanowires for Quantum Devices: Superconductivity in semiconductor nanostructures contains fascinating\nphysics due to the interplay between Andreev reflection, spin, and orbital\ninteractions. New material hybrids can access new quantum regimes and\nphenomena. Here, we report the realization of epitaxial indium thin films on\nPbTe nanowires.The film is continuous and forms an atomically sharp interface\nwith PbTe.Tunneling devices reveal a hard superconducting gap.The gap size,\n1.08 to 1.18 meV, is twice as large as bulk indium (around 0.5 meV), due to the\npresence of PbTe. A similar enhancement is also observed in the critical\ntemperature of In on a PbTe substrate. Zero bias conductance peaks appear at\nfinite magnetic fields. The effective g-factor (15 to 45) is notably enhanced\ncompared to bare PbTe wires (less than 10) due to the presence of In, differing\nfrom Al-hybrids. Josephson devices exhibit gate-tunable supercurrents. The\nPbTe-In hybrid enhances the properties of both, the superconductivity of In and\ng-factors of PbTe, and thus may enable exotic phases of matter such as\ntopological superconductivity.",
        "positive": "Evidence of high-temperature exciton condensation in a two-dimensional\n  semimetal: Electrons and holes can spontaneously form excitons and condense in a\nsemimetal or semiconductor, as predicted decades ago. This type of Bose\ncondensation can happen at much higher temperatures in comparison with dilute\natomic gases. Two-dimensional (2D) materials with reduced Coulomb screening\naround the Fermi level are promising for realizing such a system. Here we\nreport a change in the band structure accompanied by a phase transition at\nabout 180 K in single-layer ZrTe2 based on angle-resolved photoemission\nspectroscopy (ARPES) measurements. Below the transition temperature, gap\nopening and development of an ultra-flat band top around the zone center are\nobserved. This gap and the phase transition are rapidly suppressed with extra\ncarrier densities introduced by adding more layers or dopants on the surface.\nThe results suggest the formation of an excitonic insulating ground state in\nsingle-layer ZrTe2, and the findings are rationalized by first principles\ncalculations and a self-consistent mean-field theory. Our study provides\nevidence for exciton condensation in a 2D semimetal and demonstrates strong\ndimensionality effects on the formation of intrinsic bound electron-hole pairs\nin solids."
    },
    {
        "anchor": "3D quantum Hall effect of Fermi arcs in topological semimetals: The quantum Hall effect is usually observed in 2D systems. We show that the\nFermi arcs can give rise to a distinctive 3D quantum Hall effect in topological\nsemimetals. Because of the topological constraint, the Fermi arc at a single\nsurface has an open Fermi surface, which cannot host the quantum Hall effect.\nVia a \"wormhole\" tunneling assisted by the Weyl nodes, the Fermi arcs at\nopposite surfaces can form a complete Fermi loop and support the quantum Hall\neffect. The edge states of the Fermi arcs show a unique 3D distribution, giving\nan example of (d-2)-dimensional boundary states. This is distinctly different\nfrom the surface-state quantum Hall effect from a single surface of topological\ninsulator. As the Fermi energy sweeps through the Weyl nodes, the sheet Hall\nconductivity evolves from the 1/B dependence to quantized plateaus at the Weyl\nnodes. This behavior can be realized by tuning gate voltages in a slab of\ntopological semimetal, such as the TaAs family, Cd$_3$As$_2$, or Na$_3$Bi. This\nwork will be instructive not only for searching transport signatures of the\nFermi arcs but also for exploring novel electron gases in other topological\nphases of matter.",
        "positive": "Spectroscopy of Quantum-Dot Orbitals with In-Plane Magnetic Fields: We show that in-plane-magnetic-field assisted spectroscopy allows extraction\nof the in-plane orientation and full 3D shape of the quantum mechanical\norbitals of a single electron GaAs lateral quantum dot with sub-nm precision.\nThe method is based on measuring orbital energies in a magnetic field with\nvarious strengths and orientations in the plane of the 2D electron gas. As a\nresult, we deduce the microscopic quantum dot confinement potential landscape,\nand quantify the degree by which it differs from a harmonic oscillator\npotential. The spectroscopy is used to validate shape manipulation with gate\nvoltages, agreeing with expectations from the gate layout. Our measurements\ndemonstrate a versatile tool for quantum dots with one dominant axis of strong\nconfinement."
    },
    {
        "anchor": "Adsorption and ultrafast diffusion of lithium in bilayer graphene ab\n  initio and kinetic Monte Carlo simulation study: In this work, we adopt first-principle calculations based on density\nfunctional theory and Kinetic Monte Carlo simulations to investigate the\nadsorption and diffusion of lithium in bilayer graphene (BLG) as anodes in\nlithium-ion batteries. Based on energy barriers directly obtained from\nfirst-principle calculations for single-Li and two-Li intercalated BLG, a new\nequation was deduced for predicting energy barriers considering Li's\ninteractions for multi-Li intercalated BLG. Our calculated results indicate\nthat Li energetically prefers to intercalate within rather than adsorb outside\nthe bilayer graphene. Additionally, lithium exists in cationic state in the\nbilayer graphene. More excitingly, ultrafast Li diffusion coefficient, within\nAB-stacked BLG near room temperature was obtained, which reproduces the\nultrafast Li diffusion coefficient measured in recent experiment. However,\nultrafast Li diffusion was not found within AA-stacked BLG near room\ntemperature. The analyses of potential distribution indicate that the stacking\nstructure of BLG greatly affects its height of potential well within BLG, which\ndirectly leads to the large difference in Li diffusion. Furthermore, it is\nfound that both the interaction among Li ions and the stacking, structure cause\nLi diffusion within AB-stacked BLG to exhibit directional preference. Finally,\nthe temperature dependence of Li diffusion is described by the Arrhenius law.\nThese findings suggest that the stacking structure of BLG has an important\ninfluence on Li diffusion within BLG, and changing the stacking structure of\nBLG is one possible way to greatly improve Li diffusion rate within BLG. At\nlast, it is suggested that AB-stacked BLG can be an excellent candidate for\nanode material in Lithium-ion batteries.",
        "positive": "Doping-less Tunnel Field Effect Transistor: Design and Investigation: Using calibrated simulations, we report a detailed study of the doping-less\ntunnel field effect transistor (TFET) on a thin intrinsic silicon film using\ncharge plasma concept. Without the need for any doping, the source and drain\nregions are formed using the charge plasma concept by choosing appropriate work\nfunctions for the source and drain metal electrodes. Our results show that the\nperformance of the doping-less TFET is similar to that of a corresponding doped\nTFET. The doping-less TFET is expected to be free from problems associated with\nrandom dopant fluctuations. Further, fabrication of doping-less TFET does not\nrequire high-temperature doping/annealing processes and therefore, cuts down\nthe thermal budget opening up the possibilities for fabricating TFETs on single\ncrystal silicon-on-glass substrates formed by wafer scale epitaxial transfer."
    },
    {
        "anchor": "Effect of phonon dispersion on thermal conduction across Si/Ge\n  interfaces: We report finite-volume simulations of the phonon Boltzmann transport\nequation (BTE) for heat conduction across the heterogeneous interfaces in SiGe\nsuperlattices. The diffuse mismatch model incorporating phonon dispersion and\npolarization is implemented over a wide range of Knudsen numbers. The results\nindicate that the thermal conductivity of a Si/Ge superlattice is much lower\nthan that of the constitutive bulk materials for superlattice periods in the\nsubmicron regime. We report results for effective thermal conductivity of\nvarious material volume fractions and superlattice periods. Details of the\nnon-equilibrium energy exchange between optical and acoustic phonons that\noriginate from the mismatch of phonon spectra in silicon and germanium are\ndelineated for the first time. Conditions are identified for which this effect\ncan produce significantly more thermal resistance than that due to boundary\nscattering of phonons.",
        "positive": "Strong spin-orbit interaction and $g$-factor renormalization of hole\n  spins in Ge/Si nanowire quantum dots: The spin-orbit interaction lies at the heart of quantum computation with spin\nqubits, research on topologically non-trivial states, and various applications\nin spintronics. Hole spins in Ge/Si core/shell nanowires experience a\nspin-orbit interaction that has been predicted to be both strong and\nelectrically tunable, making them a particularly promising platform for\nresearch in these fields. We experimentally determine the strength of\nspin-orbit interaction of hole spins confined to a double quantum dot in a\nGe/Si nanowire by measuring spin-mixing transitions inside a regime of\nspin-blockaded transport. We find a remarkably short spin-orbit length of\n$\\sim$65 nm, comparable to the quantum dot length and the interdot distance. We\nadditionally observe a large orbital effect of the applied magnetic field on\nthe hole states, resulting in a large magnetic field dependence of the\nspin-mixing transition energies. Strikingly, together with these orbital\neffects, the strong spin-orbit interaction causes a significant enhancement of\nthe $g$-factor with magnetic field.The large spin-orbit interaction strength\ndemonstrated is consistent with the predicted direct Rashba spin-orbit\ninteraction in this material system and is expected to enable ultrafast Rabi\noscillations of spin qubits and efficient qubit-qubit interactions, as well as\nprovide a platform suitable for studying Majorana zero modes."
    },
    {
        "anchor": "Novel properties of graphene in the presence of energy gap: optics,\n  transport and mobility studies: We review the transmission of Dirac electrons through a potential barrier in\nthe presence of circularly polarized light. A different type of transmission is\ndemonstrated and explained. Perfect transmission for nearly head-on collision\nin inffnite graphene is suppressed in gapped dressed states of electrons. We\nalso present our results on enhanced mobility of hot Dirac electrons in\nnanoribbons and magnetoplasmons in graphene in the presence of the energy gap.\nThe calculated carrier mobility for a graphene nanoribbon as a function of the\nbias field possesses a high threshold for entering the nonlinear transport\nregime. This threshold is a function of both extrinsic and intrinsic\nproperties, such as lattice temperature, linear density, impurity scattering\nstrength, ribbon width, and correlation length for the line-edge roughness.\nAnalysis of non-equilibrium carrier distribution function confirms that the\ndifference between linear and nonlinear transport is due to sweeping electrons\nfrom the right to left Fermi one through elastic scattering as well as moving\nelectrons from low to high-energy ones through field-induced heating. The\nplasmons, as well as the electron-hole continuum are determined by both energy\ngap and the magnetic field, showing very specific features, which have been\nstudied and discussed in details.",
        "positive": "Intrinsic Spin Hall Effect in 5d Metals Calculated from Ab-Initio\n  Transport Theory: We describe how the spin Hall effect (SHE) can be studied from ab-initio by\ncombining density functional theory with the non-equilibrium Green's functions\ntechnique for quantum transport into the so-called DFT+NEGF method. After\nlaying down our theoretical approach in particular discussing how to compute\ncharge and spin bond currents, DFT+NEGF calculations are carried out for ideal\nclean systems. In these the transport is ballistic and the linear response\nlimit is met. The SHE emerges in a central region attached to two leads when we\napply a bias voltage so that electrons are accelerated by a uniform electric\nfield. As a result, we obtain a finite spin-Hall current and, by performing a\nscaling analysis with respect to the system size, we estimate the ballistic\nspin Hall conductivity (SHC). We consider 5d metals with fcc and bcc crystal\nstructures, finding that the SHC exhibits a rough qualitative dependence on the\nd-band filling, and comment on these results in relation to existing\nliterature. Finally, within the same DFT+NEGF approach, we also predict the\nappearance of a current-induced spin dipole moment inside the materials' unit\ncell and estimate its magnitude."
    },
    {
        "anchor": "Edge states of mechanical diamond and its topological origin: A mechanical diamond, a classical mechanics of a spring-mass model arrayed on\na diamond lattice, is discussed topologically. Its frequency dispersion\npossesses an intrinsic nodal structure in the three-dimensional Brillouin zone\n(BZ) protected by the chiral symmetry. Topological changes of the line nodes\nare demonstrated associated with modification of the tension. The line nodes\nprojected into two-dimensional BZ form loops which are characterized by the\nquantized Zak phases by 0 and $\\pi$. With boundaries, edge states are discussed\nin relation to the Zak phases and winding numbers. It establishes a bulk-edge\ncorrespondence of the mechanical diamond.",
        "positive": "Disorder-generated non-Abelions: Two classes of topological superconductors and Majorana modes in condensed\nmatter systems are known to date: one, in which impurity disorder strongly\nsuppresses topological superconducting gap and is detrimental to Majorana\nmodes, and the other, where Majorana fermions are protected by disorder-robust\nsuperconductor gap. In this work we predict a third class of topological\nsuperconductivity and Majorana modes, in which they appear exclusively in the\npresence of impurity disorder. Observation and control of Majorana fermions and\nother non-Abelions often requires a symmetry leading to a gap in a\nsingle-particle spectra. Disorder introduces states into the gap and enables\nconductance and proximity-induced superconductivity via the in-gap states. We\nshow that disorder-enabled topological superconductivity can be realized in a\nquantum Hall ferromagnet, when helical domain walls are coupled to an s-wave\nsuperconductor. Solving a general quantum mechanical problem of impurity bound\nstates in a system of spin-orbit coupled Landau levels, we show that\ndisorder-induced Majorana modes emerge in a setting of the quantum Hall\nferromagnetic transition in a CdMnTe quantum wells at a filling factor $\\nu=2$.\nRecent experiments on transport through electrostatically controlled single\ndomain wall in this system indicated the vital role of disorder in conductance,\nbut left an unresolved question whether this could intrinsically preclude\ngeneration of Majorana fermions. The proposed resolution of the problem,\ndemonstrating emergence of Majorana fermions exclusively due to impurity\ndisorder, opens a path forward. We show that electrostatic control of domain\nwalls in an integer quantum Hall ferromagnet allows manipulation of Majorana\nmodes. Similar physics can emerge for ferromagnetic transitions in the\nfractional quantum Hall regime leading to the formation and control of higher\norder non-Abelian excitations."
    },
    {
        "anchor": "Bose-Einstein Condensation in Gap-Confined Exciton-Polariton States: The development of patterned multi-quantum well heterostructures in\nGaAs/AlGaAs waveguides has recently allowed to achieve exciton-polariton\ncondensation in a topologically protected bound state in the continuum (BIC).\nRemarkably, condensation occurred above a saddle point of the polariton\ndispersion. A rigorous analysis of the condensation phenomenon in these\nsystems, as well as the role of the BIC, is still missing. In the present\nLetter we theoretically and experimentally fill this gap, by showing that\npolariton confinement resulting from the negative effective mass and the\nphotonic energy gap in the dispersion play a key role in enhancing the\nrelaxation towards the condensed state. In fact, our results show that\nlow-threshold polariton condensation is achieved within the effective trap\ncreated by the exciting laser spot regardless of whether the resulting confined\nmode is long-lived (polariton BIC) or short-lived (lossy mode). In both cases,\nthe spatial quantization of the polariton condensate and the threshold\ndifferences associated to the corresponding state lifetime are measured and\ncharacterized. For a given negative mass, a slightly lower condensation\nthreshold from the polariton BIC mode is found and associated to its suppressed\nradiative losses as compared to the lossy one.",
        "positive": "The threshold effects in one-dimensional strongly-interacting systems\n  out of equilibrium: In this work we investigate the phenomena associated with the new thresholds\nin the spectrum of excitations arising when different one-dimensional strongly\ninteracting systems are voltage biased and weakly coupled by tunneling. We\ndevelop the perturbation theory with respect to tunneling and derive an\nasymptotic behavior of physical quantities close to threshold energies. We\nreproduce earlier results for the electron relaxation at the edge of an integer\nquantum Hall system and for the non-equilibrium Fermi edge singularity\nphenomenon. In contrast to the previous works, our analysis does not rely on\nthe free-fermionic character of local tunneling, therefore we are able to\nextend our theory to wider class of systems, without well-defined electron\nexcitations, such as spinless Luttinger liquids and chiral quantum Hall edge\nstates at fractional filling factors."
    },
    {
        "anchor": "Finite-temperature phase transitions in $\u03bd=2$ bilayer quantum Hall\n  systems: In this paper, the influence of an in-plane magnetic field B_\\parallel on the\nfinite-temperature phase transitions in nu=2 bilayer quantum Hall systems are\nexamined. It is found that there can exist two types of finite-temperature\nphase transitions. The first is the Kosterlitz-Thouless (KT) transitions, which\ncan have an unusual non-monotonic dependence on B_\\parallel; the second type\noriginates from the crossing of energy levels and always increases with\nB_\\parallel. Based on these results, we point out that the threshold\ntemperature observed in the inelastic light scattering experiments cannot be\nthe KT transition temperature, because the latter shows a totally different\nB_\\parallel-dependence as compared with the experimental observation. Instead,\nit should be the level-crossing temperature, which we found agrees with the\nB_\\parallel-dependence observed. Moreover, combining the knowledge of these two\ntransition temperatures, a complete finite-temperature phase diagram is\npresented.",
        "positive": "The chiral biquadratic pair interaction: Magnetic interactions underpin a plethora of magnetic states of matter, hence\nplaying a central role both in fundamental physics and for future spintronic\nand quantum computation devices. The Dzyaloshinskii-Moriya interaction, being\nchiral and driven by relativistic effects, leads to the stabilization of\nhighly-noncollinear spin textures such as skyrmions, which thanks to their\ntopological nature are promising building blocks for magnetic data storage and\nprocessing elements. Here, we reveal and study a new chiral pair interaction,\nwhich is the biquadratic equivalent of the Dzyaloshinskii-Moriya interaction.\nFirst, we derive this interaction and its guiding principles from a microscopic\nmodel. Second, we study its properties in the simplest prototypical systems,\nmagnetic dimers deposited on various substrates, resorting to systematic\nfirst-principles calculations. Lastly, we discuss its importance and\nimplications not only for magnetic dimers but also for extended systems, namely\none-dimensional spin spirals and complex two-dimensional magnetic structures,\nsuch as a nanoskyrmion lattice."
    },
    {
        "anchor": "A micro-structured ion-implanted magnonic crystal: We investigate spin-wave propagation in a microstructured magnonic-crystal\nwaveguide fabricated by localized ion implantation. The irradiation caused a\nperiodic variation in the saturation magnetization along the waveguide. As a\nconsequence, the spin-wave transmission spectrum exhibits a set of frequency\nbands, where spin-wave propagation is suppressed. A weak modification of the\nsaturation magnetization by 7% is sufficient to decrease the spin-wave\ntransmission in the band gaps by a factor of 10. These results evidence the\napplicability of localized ion implantation for the fabrication of efficient\nmicron- and nano-sized magnonic crystals for magnon spintronic applications.",
        "positive": "Ice phonon spectra and Bayes inference: a gateway to a new understanding\n  of terahertz sound propagation in water: Understanding how molecules engage in collective motions in a liquid where a\nnetwork of bonds exists has both fundamental and applied relevance. On the one\nhand, it can elucidate the ``ordering\" role of long-range correlations in an\notherwise strongly dissipative system; on the other hand, it can inspire new\navenues to control such order to implement sound manipulation. Water represents\nan ideal investigation case to unfold these general aspects and, across the\ndecades, it has been the focus of thorough scrutiny. Despite this investigative\neffort, the spectrum of terahertz density fluctuations of water largely remains\na puzzle for Condensed Matter physicists. To unravel it, we compare previous\nscattering measurements of water spectra with new ones on ice. Thanks to the\nunique asset of Bayesian inference, we draw a more detailed portrayal of the\nphonon response of ice. The comparison with the one of liquid water challenges\nthe current understanding of density fluctuations in water, or more in general,\nof any networked liquid."
    },
    {
        "anchor": "Theroy of anisotropic plasmons: We develop the complete theory for the collective plasmon modes of an\ninteracting electron system in the presence of explicit mass (or velocity)\nanisotropy in the corresponding non-interacting situation, with the effective\nFermi velocity being different along different axes. Such effective mass\nanisotropy is common in solid state materials (e.g., silicon or germanium),\nwhere the Fermi surface is often not spherical. We find that the plasmon\ndispersion itself develops significant anisotropy in such systems, and the\ncommonly used isotropic approximation of using a density of states or optical\neffective mass does not work for the anisotropic system. We predict a\nqualitatively new phenomenon in anisotropic systems with no corresponding\nisotropic analog, where the plasmon mode along one direction decays into\nelectron-hole pairs through Landau damping while the mode remains undamped and\nstable along a different directions",
        "positive": "Effective field theory and tunneling currents in the fractional quantum\n  Hall effect: We review the construction of a low-energy effective field theory and its\nstate space for \"abelian\" quantum Hall fluids. The scaling limit of the\nincompressible fluid is described by a Chern-Simons theory in 2+1 dimensions on\na manifold with boundary. In such a field theory, gauge invariance implies the\npresence of anomalous chiral modes localized on the edge of the sample. We\nassume a simple boundary structure, i.e., the absence of a reconstructed edge.\nFor the bulk, we consider a multiply connected planar geometry. We study\ntunneling processes between two boundary components of the fluid and calculate\nthe tunneling current to lowest order in perturbation theory as a function of\ndc bias voltage. Particular attention is paid to the special cases when the\nedge modes propagate at the same speed, and when they exhibit two significantly\ndistinct propagation speeds. We distinguish between two \"geometries\" of\ninterference contours corresponding to the (electronic) Fabry-Perot and\nMach-Zehnder interferometers, respectively. We find that the interference term\nin the current is absent when exactly one hole in the fluid corresponding to\none of the two edge components involved in the tunneling processes lies inside\nthe interference contour (i.e., in the case of a Mach-Zehnder interferometer).\nWe analyze the dependence of the tunneling current on the state of the quantum\nHall fluid and on the external magnetic flux through the sample."
    },
    {
        "anchor": "Magnetoresistance of antidot lattices with grain boundaries: The magnetotransport properties of antidot lattices containing artificially\ndesigned grain boundaries have been measured. We find that the grain boundaries\nbroaden the commensurability resonances and displace them anisotropically.\nThese phenomena are unexpectedly weak but differ characteristically from\nisotropic, Gaussian disorder in the antidot positions. The observations are\ninterpreted in terms of semiclassical trajectories which tend to localize along\nthe grain boundaries within certain magnetic field intervals. Furthermore, our\nresults indicate how the transport through superlattices generated by\nself-organizing templates may get influenced by grain boundaries.",
        "positive": "A prohibition of equilibrium spin currents in multi-terminal ballistic\n  devices: We show that in the multi-terminal ballistic devices with intrinsic\nspin-orbit interaction connected to normal metal contacts there are no\nequilibrium spin currents present at any given electron energy. Obviously, this\nstatement holds also after the integration over all occupied states. Based on\nthe proof of this fact, a number of scenarios involving nonequilibrium spin\ncurrents is identified and further analyzed. In particular, it is shown that an\narbitrary two-terminal device cannot polarize transient current. The same is\ntrue for the output terminal of an N-terminal device when all N-1 inputs are\nconnected in parallel."
    },
    {
        "anchor": "Temperature dependence of photoluminescence intensity and spin contrast\n  in nitrogen-vacancy centers: We report on measurements of the photoluminescence (PL) properties of single\nnitrogen-vacancy (NV) centers in diamond at temperatures between 4-300 K. We\nobserve a strong reduction of the PL intensity and spin contrast between ca.\n10-100 K that recovers to high levels below and above. Further, we find a rich\ndependence on magnetic bias field and crystal strain. We develop a\ncomprehensive model based on spin mixing and orbital hopping in the electronic\nexcited state that quantitatively explains the observations. Beyond a more\ncomplete understanding of the excited-state dynamics, our work provides a novel\napproach for probing electron-phonon interactions and a predictive tool for\noptimizing experimental conditions for quantum applications.",
        "positive": "Graphene-based spin switch device via modulated Rashba field and strain: We investigate the spin-resolved transport in a two-terminal zigzag graphene\nnanoribbon device with two independent gate induced Rashba spin-orbit coupling\nregions and in the presence of strain. By employing a recursive Green's\nfunction technique to the tight-binding model for the graphene nanoribbon, we\ncalculate the spin-resolved conductance of the system. We show that by\nswitching the sign of one of the gates it is possible to select which spin\ncomponent will be transmitted. Moreover, our results show that an uniaxial\nstrain applied to the nanoribbon plays a significant role in the transport,\nproviding and additional manner to control the spin-polarized conductance. This\nmakes the present system a potential candidate for future implementations of\nspin-based mechanical strain sensors."
    },
    {
        "anchor": "Perfectly conducting channel on the dark surface of weak topological\n  insulators: A weak topological insulator (WTI) bears, generally, an even number of Dirac\ncones on its surface; they are susceptible of doubling, while on the surface of\na certain orientation it shows no Dirac cone. On this \"dark\" surface of a WTI,\nwe predict the existence of a single pair of isolated 1D perfectly conducting\nchannels that forms either a closed loop or a segment of a line. The former is\nassociated typically with a single atomic-layer-thick island formed on the dark\nsurface, while the latter is shown to be the consequence of a pair of crystal\n(screw) dislocations terminating on the dark surface.",
        "positive": "Demagnetizing fields in all-optical switching: Time-resolved pump-probe measurements show ultrafast and heat accumulation\ndemagnetization in Co/Pd superlattices on glass substrates. A model of\ndemagnetizing fields and micromagnetic simulations are applied to examine the\nevolution of a demagnetized cylinder into a switched state."
    },
    {
        "anchor": "Topological Graphene plasmons in a plasmonic realization of the\n  Su-Schrieffer-Heeger Model: Graphene hybrids, made of thin insulators, graphene, and metals can support\npropagating acoustic plasmons (AGPs). The metal screening modifies the\ndispersion relation of usual graphene plasmons leading to slowly propagating\nplasmons, with record confinement of electromagnetic radiation. Here, we show\nthat a graphene monolayer, covered by a thin dielectric material and an array\nof metallic nanorods can be used as a robust platform to emulate the\nSu-Schrieffer-Heeger model. We calculate the Zak's phase of the different\nplasmonic bands to characterise their topology. The system shows bulk-edge\ncorrespondence: strongly localized interface states are generated in the domain\nwalls separating arrays in different topological phases. We find signatures of\nthe nontrivial phase which can directly be probed by far-field mid-IR\nradiation, hence allowing a direct experimental confirmation of graphene\ntopological plasmons. The robust field enhancement, highly localized nature of\nthe interface states, and their gate-tuned frequencies expand the capabilities\nof AGP-based devices.",
        "positive": "Comment on \"Theoretical design of molecular nanomagnets for magnetic\n  refrigeration\" [Appl. Phys. Lett. 103, 202410 (2013)]: Garlatti et al. [Appl. Phys. Lett. 103, 202410 (2013)] report theoretical\nsimulations aimed at showing that the best molecular nanomagnets for magnetic\nrefrigeration between T = 10 K and sub-Kelvin region are those made of strongly\nferromagnetically-coupled magnetic ions. This Comment revises such conclusion\nbased on results that, apparently, contrast with the established belief in this\nresearch field."
    },
    {
        "anchor": "Propagation of acoustic surface waves on a phononic surface investigated\n  by transient reflecting grating spectroscopy: We present a study of surface acoustic waves (SAW) propagation on a 1D\nphononic surface (PS) by mean of an heterodyne-detected transient reflecting\ngrating experiment. We excited and detected coherent stationary SAWs\ncharacterized by variable wave-vectors. The measured SAW frequencies enables\nthe characterization of the band diagram of this PS sample beyond the first\nBrillouin zone (BZ). Four different SAW frequencies have been revealed, whose\nband diagram show articulated dispersion phenomena. In order to address the\nnature of the investigated SAWs, the experimental results are compared with a\nnumerical simulation of elastic modes based on a finite element model. The\nobserved SAWs are addressed to four Bloch waves characterized by different\nfrequencies and surface energy localization. Moreover, we measured the SAW\npropagation on a flat non-phononic part of the sample surface and compared it\nwith results from the PS.",
        "positive": "Comment on \"quantum theory for mesosocopic electric circuits\".\n  Cond-mat/9907171 and cond-mat/9606206: In references cond-mat/9907171 and cond-mat/9606206 (Phys.Rev.B.53, 4927\n(1996)) by You-Quan Li and Bin Chen, was considered a mesoscopic LC circuit\nwith charge discreteness. So, it was proposed a finite difference Schroedinger\nequation for the charge time behavior. In this comment, we generalize the\ncorresponding mesoscopic Hamiltonian in order to taken into account the\ndissipative effects (resistance R). Namely, a quantum term RI, proportional to\nthe current, is added to the mesoscopic LC circuit equation. This is\ncarried-out in analogy with the theory of Caldirola-Kanai for quantum one\nparticle damping."
    },
    {
        "anchor": "Magnetic field influenced electron-impurity scattering and\n  magnetotransport: We formulate a quasiclassical theory ($\\omega_c\\tau \\lesssim 1$ with\n$\\omega_c$ as the cyclotron frequency and $\\tau$ as the relaxation time) to\nstudy the influence of magnetic field on electron-impurity scattering process\nin the two-dimensional electron gas. We introduce a general recipe based on an\nabstraction of the detailed impurity scattering process to define the\nscattering parameter such as the incoming and outgoing momentum and coordinate\njump. In this picture, we can conveniently describe the skew scattering and\ncoordinate jump, which will eventually modify the Boltzmann equation. We find\nan anomalous Hall resistivity different from the conventional Boltzmann-Drude\nresult and a negative magnetoresistivity parabolic in magnetic field. The\norigin of these results has been analyzed. The relevance between our theory and\nrecent simulation and experimental works is also discussed. Our theory\ndominates in dilute impurity system where the correlation effect is negligible.",
        "positive": "Observation of Moir\u00e9 Excitons in WSe2/WS2 Heterostructure\n  Superlattices: Moir\\'e superlattices provide a powerful tool to engineer novel quantum\nphenomena in two-dimensional (2D) heterostructures, where the interactions\nbetween the atomically thin layers qualitatively change the electronic band\nstructure of the superlattice. For example, mini-Dirac points, tunable Mott\ninsulator states, and the Hofstadter butterfly can emerge in different types of\ngraphene/boron nitride moir\\'e superlattices, while correlated insulating\nstates and superconductivity have been reported in twisted bilayer graphene\nmoir\\'e superlattices. In addition to their dramatic effects on the single\nparticle states, moir\\'e superlattices were recently predicted to host novel\nexcited states, such as moir\\'e exciton bands. Here we report the first\nobservation of moir\\'e superlattice exciton states in nearly aligned WSe2/WS2\nheterostructures. These moir\\'e exciton states manifest as multiple emergent\npeaks around the original WSe2 A exciton resonance in the absorption spectra,\nand they exhibit gate dependences that are distinctly different from that of\nthe A exciton in WSe2 monolayers and in large-twist-angle WSe2/WS2\nheterostructures. The observed phenomena can be described by a theoretical\nmodel where the periodic moir\\'e potential is much stronger than the exciton\nkinetic energy and creates multiple flat exciton minibands. The moir\\'e exciton\nbands provide an attractive platform to explore and control novel excited state\nof matter, such as topological excitons and a correlated exciton Hubbard model,\nin transition metal dichalcogenides."
    },
    {
        "anchor": "Many-body characterization of topological superconductivity: The\n  Richardson-Gaudin-Kitaev chain: What distinguishes trivial from topological superluids in interacting\nmany-body systems where the number of particles is conserved? Building on a\nclass of integrable pairing Hamiltonians, we present a number-conserving,\ninteracting variation of the Kitaev model, the Richardson-Gaudin-Kitaev chain,\nthat remains exactly solvable for periodic and antiperiodic boundary\nconditions. Our model allows us to identify fermionic parity switches that\ndistinctively characterize topological superconductivity in interacting\nmany-body systems. Although the Majorana zero-modes in this model have only a\npower-law confinement, we may still define many-body Majorana operators by\ntuning the flux to a fermion parity switch. We derive a closed-form expression\nfor an interacting topological invariant and show that the transition away from\nthe topological phase is of third order.",
        "positive": "Temperature-dependent scanning tunneling spectroscopy on the Si(557)-Au\n  surface: Room-temperature and low-temperature (77 K) scanning tunneling spectroscopy\n(STS) and voltage-dependent scanning tunneling microscopy (STM) data are used\nto study the local electronic properties of the quasi-one-dimensional\nSi(557)-Au surface in real space. A gapped local electron density of states\nnear the Gamma-point is observed at different positions of the surface, i.e.,\nat protrusions arising from Si adatoms and step-edge atoms. Within the gap\nregion, two distinct peaks are observed on the chain of localized protrusions\nattributed to Si adatoms. The energy gap widens on both types of protrusions\nafter cooling from room temperature to T = 77 K. The temperature dependence of\nthe local electronic properties can therefore not be attributed to a Peierls\ntransition occurring for the step edge only. We suggest that more attention\nshould be paid to finite-size effects on the one-dimensional segments."
    },
    {
        "anchor": "Spatial-Translation-Induced Discrete Time Crystals: A discrete time crystal is a phase unique to nonequilibrium systems, where\ndiscrete time translation symmetry is spontaneously broken. Most of\nconventional time crystals proposed so far rely on spontaneous breaking of\non-site symmetries and their corresponding on-site symmetry operations. In this\nLetter, we propose a new time crystal dubbed \"spatial-translation-induced\ndiscrete time crystal (STI-DTC)\", which is realized by spatial translation and\nits symmetry breaking. Owing to the properties of spatial translation, in this\nnew time crystal, various time crystal orders can emerge only by changing the\nfilling but not changing the driving protocol. We demonstrate that local\ntransport of charges or spins shows a nontrivial oscillation, enabling\ndetection and applications of time crystal orders. Our proposal opens up a new\navenue of realizing time crystal orders by spatial translation.",
        "positive": "Berry curvature associated to Fermi arcs in continuum and lattice Weyl\n  systems: Recently it has been discovered that in Weyl semimetals the surface state\nBerry curvature can diverge in certain regions of momentum. This occurs in a\ncontinuum description of tilted Weyl cones, which for a slab geometry results\nin the Berry curvature dipole associated to the surface Fermi arcs growing\nlinearly with slab thickness. Here we investigate analytically incarnations of\nlattice Weyl semimetals and demonstrate this diverging surface Berry curvature\nby solving for their surface states and connect these to their continuum\ndescriptions. We show how the shape of the Fermi arc and the Berry curvature\nhot-line is determined and confirm the 1/k^2 divergence of the Berry curvature\nat the end of the Fermi arc as well as the finite size effects for the Berry\ncurvature and its dipole, using finite slab calculations and surface Green's\nfunction methods. We further establish that apart from affecting the second\norder, non-linear Hall effect, the divergent Berry curvature has a strong\nimpact on other transport phenomena as the Magnus-Hall effect and the\nnon-linear chiral anomaly."
    },
    {
        "anchor": "Vacancy induced energy band gap changes of semiconducting zigzag single\n  walled carbon nanotubes: In this work, we have examined how the multi-vacancy defects induced in the\nhorizontal direction change the energetics and the electronic structure of\nsemiconducting Single-Walled Carbon Nanotubes (SWCNTs). The electronic\nstructure of SWCNTs is computed for each deformed configuration by means of\nreal space, Order(N) Tight Binding Molecular Dynamic (O(N) TBMD) simulations.\nEnergy band gap is obtained in real space through the behavior of electronic\ndensity of states (eDOS) near the Fermi level. Vacancies can effectively change\nthe energetics and hence the electronic structure of SWCNTs. In this study, we\nchoose three different kinds of semiconducting zigzag SWCNTs and determine the\nband gap modifications. We have selected (12,0), (13,0) and (14,0) zigzag\nSWCNTs according to n (mod 3) = 0, n (mod 3) = 1 and n (mod 3) = 2\nclassification. (12,0) SWCNT is metallic in its pristine state. The application\nof vacancies opens the electronic band gap and it goes up to 0.13 eV for a di-\nvacancy defected tube. On the other hand (13,0) and (14,0) SWCNTs are\nsemiconductors with energy band gap values of 0.44 eV and 0.55 eV in their\npristine state, respectively. Their energy band gap values decrease to 0.07 eV\nand 0.09 eV when mono-vacancy defects are induced in their horizontal\ndirections. Then the di-vacancy defects open the band gap again. So in both\ncases, the semiconducting-metallic - semiconducting transitions occur. It is\nalso shown that the band gap modification exhibits irreversible\ncharacteristics, which means that band gap values of the nanotubes do not reach\ntheir pristine values with increasing number of vacancies.",
        "positive": "Effects of interactions on periodically driven dynamically localized\n  systems: It is known that there are lattice models in which non-interacting particles\nget dynamically localized when periodic $\\delta$-function kicks are applied\nwith a particular strength. We use both numerical and analytical methods to\nstudy the effects of interactions in three different models in one dimension.\nThe systems we have considered include spinless fermions with interactions\nbetween nearest-neighbor sites, the Hubbard model of spin-1/2 fermions, and the\nBose Hubbard model with on-site interactions. We derive effective Floquet\nHamiltonians up to second order in the time period of kicking. Using these we\nshow that interactions can give rise to a variety of interesting results such\nas two-body bound states in all three models and dispersionless many-body bound\nstates for spinless fermions and bosons. We substantiate these results by exact\ndiagonalization and stroboscopic time evolution of systems with a finite number\nof particles. We derive a low-energy pseudo-spin-1/2 limit of the Bose Hubbard\nsystem in the thermodynamic limit and show that a special case of this has an\nexponentially large number of ground states. Finally we study the effect of\nchanging the strength of the $\\delta$-function kicks slightly away from perfect\ndynamical localization; we find that a single particle remains dynamically\nlocalized for a long time after which it moves ballistically."
    },
    {
        "anchor": "Dynamical Coulomb Blockade and the Derivative Discontinuity of\n  Time-Dependent Density Functional Theory: The role of the discontinuity of the exchange-correlation potential of\ndensity functional theory is studied in the context of electron transport and\nshown to be intimately related to Coulomb blockade. By following the time\nevolution of an interacting nanojunction attached to biased leads, we find\nthat, instead of evolving to a steady state, the system reaches a dynamical\nstate characterized by correlation-induced current oscillations. Our results\nestablish a dynamical picture of Coulomb blockade manifesting itself as a\nperiodic sequence of charging and discharging of the nanostructure.",
        "positive": "Phonon-induced long-lasting nonequilibrium in the electron system of a\n  laser-excited solid: Electron-electron thermalization and electron-phonon relaxation processes in\nlaser-excited solids are often assumed to occur on different timescales. This\nis true for the majority of the conduction band electrons in a metal. However,\nelectron-phonon interactions can influence the thermalization process of the\nexcited electrons. We study the interplay of the underlying scattering\nmechanisms for the case of a noble metal with help of a set of complete\nBoltzmann collision integrals. We trace the transient electron distribution in\ncopper and its deviations from a Fermi-Dirac distribution due to the excitation\nwith an ultrashort laser pulse. We investigate the different stages of\nelectronic nonequilibrium after an excitation with an ultrashort laser-pulse of\n800 nm wavelength and 10 fs pulse duration. Our calculations show a strong\nnonequilibrium during and directly after the end of the laser pulse.\nSubsequently, we find a fast thermalization of most electrons. Surprisingly, we\nobserve a long-lasting nonequilibrium, which can be attributed to the\nelectron-phonon scattering. This nonequilibrium establishes at energies around\npeaks in the density of states of the electrons and persists on the timescale\nof electron-phonon energy relaxation. It influences in turn the electron phonon\ncoupling strength."
    },
    {
        "anchor": "Ultrafast ratchet dynamics of skyrmion by defect engineering under\n  gigahertz magnetic fields: The novel ratchet motion of magnetic skyrmions driven by microwave magnetic\nfields, with the motion direction and speed tunable by field parameters,\nprovides a promising route to drive magnetic skyrmions in materials with poor\nconductivity. However, as an indirect motion, skyrmion ratchet motion speed is\ngenerally low in comparison with the direct motions driven by current. Toward\npractical applications, it is important to ask if there are mechanisms to\nrealize ultrafast ratchet motion of magnetic skyrmions and how such novel\nmotion can be integrated into racetrack-type skyrmion devices. In this work, we\nexplore the effects of defects and edges on the ratchet motion of magnetic\nskyrmions under time-varying magnetic fields in GHz. We demonstrate that the\nratchet motion of skyrmion is not only guided along the defect tracks or edges,\nbut also with a remarkable speed-up (with a factor over ten) compared with that\nin the bulk region. The skyrmion ratchet motion speed reaches 100 m/s along a\nstraight defect track/edge and 10^9 rad/s along a circular edge under a field\nof ~50 mT, comparable to those direct motions driven by currents. Moreover, the\nskyrmion ratchet motion along the defect track/edge can be facilely controlled\nby the field and defect parameters. Analysis based on time-averaged Thiele\nequation of skyrmion verifies that such a speed-up effect is due to the\nincreased time-averaged driving force perpendicular to the skyrmion motion when\nit approaches the defect track or edge, analogous to that discovered in direct\nmotions driven by currents.",
        "positive": "Effect of anisotropic band curvature on carrier multiplication in\n  graphene: We study relaxation of an excited electron in the conduction band of\nintrinsic graphene at zero temperature due to production of interband\nelectron-hole pairs. The electronic band curvature, being anisotropic because\nof trigonal warping, is shown to suppress relaxation for a range of directions\nof the initial electron momentum. For other directions, relaxation is allowed\nonly if the curvature exceeds a finite critical value; otherwise, a\nnon-decaying quasiparticle state is found to exist."
    },
    {
        "anchor": "Machine learning of phase transitions in nonlinear polariton lattices: Polaritonic lattices offer a unique testbed for studying nonlinear\ndriven-dissipative physics. They show qualitative changes of a steady state as\na function of system parameters, which resemble non-equilibrium phase\ntransitions. Unlike their equilibrium counterparts, these transitions cannot be\ncharacterised by conventional statistical physics methods. Here, we study a\nlattice of square-arranged polariton condensates with nearest-neighbour\ncoupling, and simulate the polarisation (pseudo-spin) dynamics of the polariton\nlattice, observing regions with distinct steady-state polarisation patterns. We\nclassify these patterns using machine learning methods and determine the\nboundaries separating different regions. First, we use unsupervised data mining\ntechniques to sketch the boundaries of phase transitions. We then apply\nlearning by confusion, a neural network-based method for learning labels in the\ndataset, and extract the polaritonic phase diagram. Our work takes a step\ntowards AI-enabled studies of polaritonic systems.",
        "positive": "Zero-line modes at stacking faulted domain walls in multilayer graphene: Rhombohedral multilayer graphene is a physical realization of the chiral\ntwo-dimensional electron gas that can host zero-line modes (ZLMs), also known\nas kink states, when the local ap opened by inversion symmetry breaking\npotential changes sign in real space. Here we study how the variations in the\nlocal stacking coordination of multilayer graphene affects the formation of the\nZLMs. Our analysis indicates that the valley Hall effect develops whenever an\ninterlayer potential difference is able to open up a band gap in stacking\nfaulted multilayer graphene, and that ZLMs can appear at the domain walls\nseparating two distinct regions with imperfect rhombohedral stacking\nconfigurations. Based on a tight-binding formulation with distant hopping terms\nbetween carbon atoms, we first show that topologically distinct domains\ncharacterized by the valley Chern number are separated by a metallic region\nconnecting AA and AA$'$ stacking line in the layer translation vector space. We\nfind that gapless states appear at the interface between the two stacking\nfaulted domains with different layer translation or with opposite perpendicular\nelectric field if their valley Chern numbers are different."
    },
    {
        "anchor": "Emergent dual topology in the three-dimensional Kane-Mele Pt$_2$HgSe$_3$: Recently, the very first large-gap Kane-Mele quantum spin Hall insulator was\npredicted to be monolayer jacutingaite (Pt$_2$HgSe$_3$), a naturally-occurring\nexfoliable mineral discovered in Brazil in 2008. The stacking of quantum spin\nHall monolayers into a van-der-Waals layered crystal typically leads to a\n(0;001) weak topological phase, which does not protect the existence of surface\nstates on the (001) surface. Unexpectedly, recent angle-resolved photoemission\nspectroscopy experiments revealed the presence of surface states dispersing\nover large areas of the 001-surface Brillouin zone of jacutingaite single\ncrystals. The 001-surface states have been shown to be topologically protected\nby a mirror Chern number $C_M=-2$, associated with a nodal line gapped by\nspin-orbit interactions. Here, we extend the two-dimensional Kane-Mele model to\nbulk jacutingaite and unveil the microscopic origin of the gapped nodal line\nand the emerging crystalline topological order. By using maximally-localized\nWannier functions, we identify a large non-trivial second nearest-layer hopping\nterm that breaks the standard paradigm of weak topological insulators.\nComplemented by this term, the predictions of the Kane-Mele model are in\nremarkable agreement with recent experiments and first-principles simulations,\nproviding an appealing conceptual framework also relevant for other layered\nmaterials made of stacked honeycomb lattices.",
        "positive": "Majorana fermions on the quantum Hall edge: Superconductivity and the quantum Hall effect are considered to be two\ncornerstones of condensed matter physics. The realization of hybrid structures\nwhere these two effects coexist has recently become an active field of\nresearch. In this work, we study a Josephson junction where a central region in\nthe quantum Hall regime is proximitized with superconductors that can be driven\nto a topological phase with an external Zeeman field. In this regime, the\nMajorana modes that emerge at the ends of each superconducting lead couple to\nthe chiral quantum Hall edge states. This produces distinguishable features in\nthe Andreev levels and Fraunhofer patterns that could help in detecting not\nonly the topological phase transition but also the spin degree of freedom of\nthese exotic quasiparticles. The current phase relation and the spectral\nproperties of the junction throughout the topological transition are fully\ndescribed by a numerical tight-binding calculation. In pursuance of the\nunderstanding of these results, we develop a low-energy spinful model that\ncaptures the main features of the numerical transport simulations in the\ntopological phase."
    },
    {
        "anchor": "Spin Transport in Organic Semiconductors: A Brief Overview of the First\n  Eight Years: In this article we briefly review the current state of the experimental\nresearch on spin polarized transport in organic semiconductors. These systems,\nwhich include small molecular weight compounds and polymers, are central in the\nrapidly maturing area of organic electronics. A great deal of effort has been\ninvested in the last eight years toward understanding spin injection and\ntransport in organics. These developments have opened up the possibility of\nrealizing a new family of organic spintronic devices which will blend the\nchemical versatility of organic materials with spintronic functionalities.",
        "positive": "Thermal conductivity spectrum calculation from first-principles-based\n  harmonic phonon theory: In recent years, nanostructuring of dielectric and semiconducting crystals\nhas enhanced controllability of their thermal conductivity. To carry out\ncomputational material search for nanostructured materials with desirable\nthermal conductivity, a key property is the thermal conductivity spectrum of\nthe original single crystal, which determines the appropriate length scale of\nnanostructures and mutual adaptability of different kinds of nanostructures.\nAlthough the first-principles phonon transport calculations have become\naccessible, the anharmonic lattice dynamics calculations are still heavy to\nscan many materials. To this end, we have developed an empirical model that\ndescribes the thermal conductivity spectrum in terms only of harmonic phonon\nproperties and bulk thermal conductivity. The model was tested for several\ncrystals with different structures and thermal conductivities, and was\nconfirmed to reproduce the overall profiles of thermal conductivity spectra and\ntheir anharmonic calculations."
    },
    {
        "anchor": "Energy and Momentum Distribution of Surface Plasmon-induced Hot Carriers\n  Isolated via Spatiotemporal Separation: Understanding the differences between photon-induced and plasmon-induced hot\nelectrons is essential for the construction of devices for plasmonic energy\nconversion. The mechanism of the plasmonic enhancement in photochemistry,\nphotocatalysis, and light-harvesting and especially the role of hot carriers is\nstill heavily discussed. The question remains, if plasmon-induced and\nphoton-induced hot carriers are fundamentally different, or if plasmonic\nenhancement is only an effect of field concentration producing these carriers\nin greater numbers. For the bulk plasmon resonance, a fundamental difference is\nknown, yet for the technologically important surface plasmons this is far from\nbeing settled. The direct imaging of surface plasmon-induced hot carriers could\nprovide essential insight, but the separation of the influence of driving\nlaser, field-enhancement, and fundamental plasmon decay has proven to be\ndifficult. Here, we present an approach using a two-color femtosecond\npump-probe scheme in time-resolved 2-photon-photoemission (tr-2PPE), supported\nby a theoretical analysis of the light and plasmon energy flow. We separate the\nenergy and momentum distribution of the plasmon-induced hot electrons from the\none of photoexcited electrons by following the spatial evolution of\nphotoemitted electrons with energy-resolved Photoemission Electron Microscopy\n(PEEM) and Momentum Microscopy during the propagation of a Surface Plasmon\nPolariton (SPP) pulse along a gold surface. With this scheme, we realize a\ndirect experimental access to plasmon-induced hot electrons. We find a\nplasmonic enhancement towards high excitation energies and small in-plane\nmomenta, which suggests a fundamentally different mechanism of hot electron\ngeneration, as previously unknown for surface plasmons.",
        "positive": "Photoexcitation in two-dimensional topological insulators: Generating\n  and controlling electron wavepackets in Quantum Spin Hall systems: One of the most fascinating challenges in Physics is the realization of an\nelectron-based counterpart of quantum optics, which requires the capability to\ngenerate and control single electron wave packets. The edge states of quantum\nspin Hall (QSH) systems, i.e. two-dimensional (2D) topological insulators\nrealized in HgTe/CdTe and InAs/GaSb quantum wells, may turn the tide in the\nfield, as they do not require the magnetic field that limits the\nimplementations based on quantum Hall effect. Here we show that an electric\npulse, localized in space and/or time and applied at a QSH edge, can\nphotoexcite electron wavepackets by intra-branch electrical transitions,\nwithout invoking the bulk states or the Zeeman coupling. Such wavepackets are\nspin-polarised and propagate in opposite directions, with a density profile\nthat is independent of the initial equilibrium temperature and that does not\nexhibit dispersion, as a result of the linearity of the spectrum and of the\nchiral anomaly characterising massless Dirac electrons. We also investigate the\nphotoexcited energy distribution and show how, under appropriate circumstances,\nminimal excitations (Levitons) are generated. Furthermore, we show that the\npresence of a Rashba spin-orbit coupling can be exploited to tailor the shape\nof photoexcited wavepackets. Possible experimental realizations are also\ndiscussed."
    },
    {
        "anchor": "Topological phase transitions driven by polarity change and\n  next-nearest-neighbor hopping in skyrmion crystals: By considering the bulk-edge correspondence of the skyrmion crystal this work\nfocused on the relation of the topological properties to the polarity\n($Q_{\\rm{sk}}$), next-nearest-neighbor hopping ($t'$), and exchange coupling\n($J$). We found that by continually increasing polarity of the skyrmions from 1\nto 2, the monopole-lattice phase and the dipole-lattice phase both span a wide\nrange in the parameter space demonstrating topological robustness. While the\nnext-nearest-neighbor-hopping of the electrons coexists with the\nnearest-neighbor hopping the flux pattern of the emergent magnetic field\ntraversing the two-dimensional SkX is reshaped giving rise to different\ntopological Hall effect. By increasing $t'$ from 0 to $t$ with the polarity\nfixed to be 1, we found Chern numbers of the electronic bands change from unity\nto indefinite values demonstrating a phase transition. We also considered the\neffect of finite $J$ and found the results obtained in the adiabatic limit hold\nto around $J=t$.",
        "positive": "Dynamical coupling and negative differential resistance from\n  interactions across the molecule-electrode interface in molecular junctions: Negative differential resistance - a decrease in current with increasing bias\nvoltage - is a counter-intuitive effect that is observed in various molecular\njunctions. Here, we present a novel mechanism that may be responsible for such\nan effect, based on strong Coulomb interaction between electrons in the\nmolecule and electrons on the atoms closest to the molecule. The Coulomb\ninteraction induces electron-hole binding across the molecule-electrode\ninterface, resulting in a renormalized and enhanced molecule-electrode\ncoupling. Using a self-consistent non-equilibrium Green's function approach, we\nshow that the effective coupling is non-monotonic in bias voltage, leading to\nnegative differential resistance. The model is in accord with recent\nexperimental observations that showed a correlation between the negative\ndifferential resistance and the coupling strength. We provide detailed\nsuggestions for experimental tests which may help to shed light on the origin\nof the negative differential resistance. Finally, we demonstrate that the\ninterface Coulomb interaction affects not only the I-V curves but also the\nthermoelectric properties of molecular junctions."
    },
    {
        "anchor": "Topological Properties of Time Reversal Symmetric Kitaev Chain and\n  Applications to Organic Superconductors: We show that the pair of Majorana modes at each end of a 1D spin triplet\nsuperconductor with total Cooper pair spin S_x=0 (i.e., Delta_{up,up} =\n-Delta_{down,down} = p*Delta_0; two uncoupled time reversed copies of the\nKitaev p-wave chain) are topologically robust to perturbations such as mixing\nby the S_z=0 component of the order parameter\n(Delta_{up,down}=Delta_{down,up}), transverse hopping (in quasi-1D systems),\nnon-magnetic disorder, and also, most importantly, to time reversal breaking\nperturbations such as applied Zeeman fields/magnetic impurities and the mixing\nby the S_y=0 component of the triplet order parameter\n(Delta_{up,up}=Delta_{down,down}). We show that the robustness to time reversal\nbreaking results from a hidden chiral symmetry which places the system in the\nBDI topological class with an integer Z invariant. Our work has important\nimplications for the quasi-1D organic superconductors (TMTSF)_2X (X=PF_6,\nCIO_4) (Bechgaard salts) which have been proposed as triplet superconductors\nwith equal spin pairing (Delta_{up,up},Delta_{down,down} \\neq 0,\nDelta_{up,down}=0) in applied magnetic fields.",
        "positive": "Fabrication and electrical transport properties of embedded graphite\n  microwires in a diamond matrix: Micrometer width and nanometer thick wires with different shapes were\nproduced $\\approx 3~\\upmu$m below the surface of a diamond crystal using a\nmicrobeam of He$^+$ ions with 1.8~MeV energy. Initial samples are amorphous and\nafter annealing at $T\\approx 1475$~K, the wires crystallized into a\ngraphite-like structures, according to confocal Raman spectroscopy\nmeasurements. The electrical resistivity at room temperature is only one order\nof magnitude larger than the in-plane resistivity of highly oriented pyrolytic\nbulk graphite and shows a small resistivity ratio($\\rho(2{\\rm K})/\\rho(315{\\rm\nK}) \\approx 1.275$). A small negative magnetoresistance below $T=200$~K was\nmeasured and can be well understood taking spin-dependent scattering processes\ninto account. The used method provides the means to design and produce\nmillimeter to micrometer sized conducting circuits with arbitrary shape\nembedded in a diamond matrix."
    },
    {
        "anchor": "Spin-valve effects in point contacts to exchange biased Co40Fe40B20\n  films: Nonlinear current-voltage characteristics and magnetoresistance of point\ncontacts between a normal metal (N) and films of amorphous ferromagnet (F)\nCo40Fe40B20 of different thickness, exchange-biased by antiferromagnetic\nMn80Ir20 are studied. A surface spin valve effect in the conductance of such\nF-N contacts is observed. The effect of exchange bias is found to be inversely\nproportional to the Co40Fe40B20 film thickness. This behavior as well as other\nmagneto-transport effects we observe on single exchange-pinned ferromagnetic\nfilms are similar in nature to those found in conventional three-layer\nspin-valves.",
        "positive": "Scanning Gate Microscopy in a Viscous Electron Fluid: We measure transport through a Ga[Al]As heterostructure at temperatures\nbetween 0.1 K and 30 K. Increasing the temperature enhances the\nelectron-electron scattering rate and viscous effects in the two-dimensional\nelectron gas arise. To probe this regime we measure so-called vicinity voltages\nand use a voltage-biased scanning tip to induce a movable local perturbation.\nWe find that the scanning gate images differentiate reliably between the\ndifferent regimes of electron transport. Our data are in good agreement with\nrecent theories for interacting electron liquids in the ballistic and viscous\nregimes stimulated by measurements in graphene. However, the range of\ntemperatures and densities where viscous effects are observable in Ga[Al]As are\nvery distinct from the graphene material system."
    },
    {
        "anchor": "Charge and spin density waves: Quasi one dimension to two dimension: Possibility of electronic charge and spin separation leading to charge\ndensity wave and spin density wave is well established in one dimensional\nsystems in presence and absence of Coulomb interaction. We start from quasi one\ndimension and show the possibility of such a transition in quasi one dimension\nas well as in two dimension by going to a regime where it can be shown for free\nelectrons that just interact via Fermi statistics. Since Coulomb interaction\ncan only facilitate the phenomenon, the purpose of our work is to show the\nphenomena unambiguously in the limit when Coulomb interaction can be ignored.\nFinally we also comment on dimensions greater than two and inclusion of Coulomb\ninteractions.",
        "positive": "OLEDs as models for bird magnetoception: detecting electron spin\n  resonance in geomagnetic fields: Certain species of living creatures are known to orientate themselves in the\ngeomagnetic field. Given the small magnitude of approximately 48 {\\mu}T, the\nunderlying quantum mechanical phenomena are expected to exhibit coherence times\napproaching the millisecond regime. In this contribution, we show sensitivity\nof organic light-emitting diodes (OLEDs) to magnetic fields far below Earth's\nmagnetic field, suggesting that coherence times of the spins of charge-carrier\npairs in these devices can be similarly long. By electron paramagnetic\nresonance (EPR) experiments, a lower bound for the coherence time can be\nassessed directly. Moreover, this technique offers the possibility to determine\nthe distribution of hyperfine fields within the organic semiconductor layer. We\nextend this technique to a material system exhibiting both fluorescence and\nphosphorescence, demonstrating stable anticorrelation between optically\ndetected magnetic resonance (ODMR) spectra in the singlet (fluorescence) and\ntriplet (phosphorescence) channel. The experiments demonstrate the extreme\nsensitivity of OLEDs to both static as well as dynamic magnetic fields and\nsuggest that coherent spin precession processes of Coulombically bound electron\nspin pairs may play a crucial role in the magnetoreceptive ability of living\ncreatures."
    },
    {
        "anchor": "Dephasing-assisted transport in linear triple quantum dots: Environmental noise usually hinders the efficiency of charge transport\nthrough coherent quantum systems; an exception is dephasing-assisted transport\n(DAT). We show that linear triple quantum dots in a transport configuration and\nsubjected to pure dephasing exhibit DAT if the coupling to the drain reservoir\nexceeds a threshold. DAT occurs for arbitrarily weak dephasing and the\nenhancement can be directly controlled by the coupling to the drain. Moreover,\nfor specific settings, the enhanced current is accompanied by a reduction in\nrelative shot noise. We identify the quantum Zeno effect and long-distance\ntunnelling as underlying dynamical processes involved in dephasing-assisted and\n-suppressed transport. Our analytical results are obtained by using the density\nmatrix formalism and the characteristic polynomial approach to full counting\nstatistics.",
        "positive": "Effective mass staircase and the Fermi liquid parameters for the\n  fractional quantum Hall composite fermions: Effective mass of the composite fermion in the fractional quantum Hall\nsystem, which is of purely interaction originated, is shown, from a numerical\nstudy, to exhibit a curious nonmonotonic behavior with a staircase correlated\nwith the number (=2,4,...) of attached flux quanta. This is surprising since\nthe usual composite-fermion picture predicts a smooth behavior. On top of that,\nsignificant interactions are shown to exist between composite fermions, where\nthe excitation spectrum is accurately reproduced in terms of Landau's Fermi\nliquid picture with negative (i.e., Hund's type) orbital and spin exchange\ninteractions."
    },
    {
        "anchor": "Dynamic Transport Characteristics of Side-Coupled Double\n  Quantum-Impurity Systems: A systematic study is made on the time-dependent dynamic transport\ncharacteristics of the side-coupled double quantum-impurity system based on the\nhierarchical equations of motion. It is found that the transport current\nbehaves like a single quantum dot when the coupling strength is low during\ntunneling or coulomb coupling. The dynamic current oscillates due to the\ntemporal coherence of the electron tunneling device only when the tunneling\ntransition is coupled. The oscillation frequency of the transport current is\nrelated to the step voltage applied by the lead, while the $T$, e-e interaction\n$U$ and the bandwidth $W$ have little influence. The amplitude of the current\noscillation exists in positive correlation with $W$ and negative correlation\nwith $U$. With the increase in coupling $t_{12}$ between impurities, the ground\nstate of the system changes from a Kondo singlet of one impurity to a\nspin-singlet of two impurities. Moreover, lowering the temperature could\npromote the Kondo effect to intensify the oscillation of the dynamic current.\nWhen only the coulomb transition is coupled, it is found that the two split-off\nHubbard peaks move upward and have different interference effects on the Kondo\npeak at the Fermi surface with the increase in $U_{12}$, from the dynamics\npoint of view.",
        "positive": "Theory of the quantum Hall effect in graphene: We study the quantum Hall effect (QHE) in graphene based on the current\ninjection model. In our model, the presence of disorder, the edge-state\npicture, extended states and localized states, which are believed to be\nindispensable ingredients in describing the QHE, do not play an important role.\nInstead the boundary conditions during the injection into the graphene sheet,\nwhich are enforced by the presence of the Ohmic contacts, determine the\ncurrent-voltage characteristics."
    },
    {
        "anchor": "Coupling between conduction and near-field radiative heat transfer in\n  tip-plane geometry: We analyze the coupling between conduction and radiative heat transfer in\nnear-field regime between two coaxial cylinders separated by a vacuum gap. By\nsolving the heat transport equation in the steady-state regime between metals\nor polar materials we highlight a flux saturation mechanism for the radiative\ntransfer even without non-local effect. In the case of polar materials this\nsaturation occurs in the separation distances range of 1 to 10 nm which can be\nexperimentally explored.",
        "positive": "Nonlinear effects in the propagation of optically generated\n  magnetostatic volume mode spin waves: Recent experimental work has demonstrated optical control of spin wave\nemission by tuning the shape of the optical pulse (Satoh et al.\\ Nature\nPhotonics, 6, 662 (2012)). We reproduce these results and extend the scope of\nthe control by investigating nonlinear effects for large amplitude excitations.\nWe observe an accumulation of spin wave power at the center of the initial\nexcitation combined with short-wavelength spin waves. These kind of nonlinear\neffects have not been observed in earlier work on nonlinearities of spin waves.\nOur observations pave the way for the manipulation of magnetic structures at a\nsmaller scale than the beam focus, for instance in devices with all-optical\ncontrol of magnetism."
    },
    {
        "anchor": "Multi-Band Mobility in Semiconducting Carbon Nanotubes: We present new data and a compact mobility model for single-wall carbon\nnanotubes, with only two adjustable parameters, the elastic and inelastic\ncollision mean free paths at 300 K. The mobility increases with diameter,\ndecreases with temperature, and has a more complex dependence on charge\ndensity. The model and data suggest the room temperature mobility does not\nexceed 10,000 cm2/V.s at high carrier density (n > 0.5 nm-1) for typical\nsingle-wall nanotube diameters, due to the strong scattering effect of the\nsecond subband.",
        "positive": "Two-Dimensional Electrostatic Lattices for Indirect Excitons: We report on a method for the realization of two-dimensional electrostatic\nlattices for excitons using patterned interdigitated electrodes. Lattice\nstructure is set by the electrode pattern and depth of the lattice potential is\ncontrolled by applied voltages. We demonstrate square, hexagonal, and honeycomb\nlattices created by this method."
    },
    {
        "anchor": "Quantum Hall ferromagnetism in graphene: a SU(4) bosonization approach: We study the quantum Hall effect in graphene at filling factors \\nu = 0 and\n\\nu = \\pm, concentrating on the quantum Hall ferromagnetic regime, within a\nnon-perturbative bosonization formalism. We start by developing a bosonization\nscheme for electrons with two discrete degrees of freedom (spin-1/2 and\npseudospin-1/2) restricted to the lowest Landau level. Three distinct phases\nare considered, namely the so-called spin-pseudospin, spin, and pseudospin\nphases. The first corresponds to a quarter-filled (\\nu =-1) while the others to\na half-filled (\\nu = 0) lowest Landau level. In each case, we show that the\nelementary neutral excitations can be treated approximately as a set of\nn-independent kinds of boson excitations. The boson representation of the\nprojected electron density, the spin, pseudospin, and mixed spin-pseudospin\ndensity operators are derived. We then apply the developed formalism to the\neffective continuous model, which includes SU(4) symmetry breaking terms,\nrecently proposed by Alicea and Fisher. For each quantum Hall state, an\neffective interacting boson model is derived and the dispersion relations of\nthe elementary excitations are analytically calculated. We propose that the\ncharged excitations (quantum Hall skyrmions) can be described as a coherent\nstate of bosons. We calculate the semiclassical limit of the boson model\nderived from the SU(4) invariant part of the original fermionic Hamiltonian and\nshow that it agrees with the results of Arovas and co-workers for SU(N) quantum\nHall skyrmions. We briefly discuss the influence of the SU(4) symmetry breaking\nterms in the skyrmion energy.",
        "positive": "Weyl Metals: Weyl metal is the first example of a conducting material with a nontrivial\nelectronic structure topology, making it distinct from an ordinary metal.\nUnlike in insulators, the nontrivial topology is not related to invariants,\nassociated with completely filled bands, but with ones, associated with the\nFermi surface. The Fermi surface of a topological metal consists of\ndisconnected sheets, each enclosing a Weyl node, which is a point of contact\nbetween two nondegenerate bands. Such a point contact acts as a source of Berry\ncurvature, or a magnetic monopole in momentum space. Its charge, or the flux of\nthe Berry curvature through the enclosing Fermi surface sheet, is a topological\ninvariant. We review the current state of this rapidly growing field, with a\nfocus on bulk transport phenomena in topological metals."
    },
    {
        "anchor": "Non-monotonic spin relaxation and decoherence in graphene quantum dots\n  with spin-orbit interactions: We investigate the spin relaxation and decoherence in a single-electron\ngraphene quantum dot with Rashba and intrinsic spin-orbit interactions. We\nderive an effective spin-phonon Hamiltonian via the Schrieffer-Wolff\ntransformation in order to calculate the spin relaxation time T_1 and\ndecoherence time T_2 within the framework of the Bloch-Redfield theory. In this\nmodel, the emergence of a non-monotonic dependence of T_1 on the external\nmagnetic field is attributed to the Rashba spin-orbit coupling-induced\nanticrossing of opposite spin states. A rapid decrease of T_1 occurs when the\nspin and orbital relaxation rates become comparable in the vicinity of the\nspin-mixing energy-level anticrossing. By contrast, the intrinsic spin-orbit\ninteraction leads to a monotonic magnetic field dependence of the spin\nrelaxation rate which is caused solely by the direct spin-phonon coupling\nmechanism. Within our model, we demonstrate that the decoherence time T_2 ~ 2\nT_1 is dominated by relaxation processes for the electron-phonon coupling\nmechanisms in graphene up to leading order in the spin-orbit interaction.\nMoreover, we show that the energy anticrossing also leads to a vanishing pure\nspin dephasing rate for these states for a super-Ohmic bath.",
        "positive": "Evaluating Spintronic Devices Using The Modular Approach: Over the past decade a large family of spintronic devices have been proposed\nas candidates for replacing CMOS for future digital logic circuits. Using the\nrecently developed Modular Approach framework, we investigate and identify the\nphysical bottlenecks and engineering challenges facing current spintronic\ndevices. We then evaluate how systematic advancements in material properties\nand device design innovations impact the performance of spintronic devices, as\na possible continuation of Moore's Law, even though some of these projections\nare speculative and may require technological breakthroughs. Lastly, we\nillustrate the use of the Modular Approach as an exploratory tool for\nprobabilistic networks, using superparamagnetic magnets as building blocks for\nsuch networks. These building blocks leverage the inherent physics of\nstochastic spin-torque switching and could provide ultra-compact and efficient\nhardware for beyond-Boolean computational paradigms."
    },
    {
        "anchor": "Polaritonic Chemistry: Collective Strong Coupling Implies Strong Local\n  Modification of Chemical Properties: Polaritonic chemistry has become a rapidly developing field within the last\nfew years. A multitude of experimental observations suggest that chemical\nproperties can be fundamentally altered and novel physical states appear when\nmatter is strongly coupled to resonant cavity modes, i.e. when hybrid\nlight-matter states emerge. Up until now, theoretical approaches to explain and\npredict these observations were either limited to phenomenological quantum\noptical models, suited to describe collective polaritonic effects, or\nalternatively to ab initio approaches for small system sizes. The later methods\nwere particularly controversial since collective effects could not be\nexplicitly included due to the intrinsically low particle numbers, which are\ncomputationally accessible. Here, we demonstrate for a nitrogen dimer chain of\nvariable size that any impurity present in a collectively coupled chemical\nensemble (e.g. temperature fluctuations or reaction process) induces local\nmodifications in the polaritonic system. From this we deduce that a novel dark\nstate is formed, whose local chemical properties are modified considerably at\nthe impurity due to the collectively coupled environment. Our simulations unify\ntheoretical predictions from quantum optical models (e.g. formation of\ncollective dark states and different polaritonic branches) with the single\nmolecule quantum chemical perspective, which relies on the (quantized)\nredistribution of local charges. Moreover, our findings suggest that the\nrecently developed QEDFT method is suitable to access these locally scaling\npolaritonic effects and it is a useful tool to better understand recent\nexperimental results and to even design novel experimental approaches. All of\nwhich paves the way for many novel discoveries and applications in polaritonic\nchemistry.",
        "positive": "Nonadiabatic Correction and Adiabatic Criteria of Noninteracting Quantum\n  Dot Systems: We theoretically study nonadiabatic corrections for charge pumping in a\nnoninteracting electron model of a single-level quantum dot. We derive a\nformula for the velocity limit of parameter driving to realize adiabatic\npumping and illustrate its features in the wide-band limit. We discuss the\neffect of the nonadiabatic corrections in terms of a typical velocity limit,\nwhich is defined by averaging the velocity limits on the parameter contour. We\nalso show that the typical velocity limit vanishes when the adiabaticity\nbreakdown occurs in a quantum dot coupled to reservoirs with a band edge."
    },
    {
        "anchor": "Strongly correlated bistable sublattice and temperature hysteresis of\n  elastic and thermal crystal properties: It is shown that in crystal lattices with a basis the cooperative behavior of\na certain type of atoms performing optical long-wavelength vibrations in a\ndouble-well potential of the field of the matrix lattice may lead to the\nformation of a bistable sublattice. As a result of the interaction of the\nmetastable states of such a sublattice with the vibrational states of the\nmatrix lattice, the elastic and thermal properties of the crystal acquire\nanomalous, hysteresis-like, temperature curves. The concepts developed in the\npaper make it possible to obtain a qualitative interpretation, which agrees\nwith the experimental data, of the hysteresis-like temperature dependence of\nthe speed and absorption of ultrasonic waves, the specific heat, and the\nthermal conductivity in superconducting yttrium and bismuth cuprates.",
        "positive": "Quantum interference tuning of spin-orbit coupling in twisted van der\n  Waals trilayers: We show that in van der Waals stacks of twisted hexagonal layers the\nproximity induced Rashba spin-orbit coupling can be affected by quantum\ninterference. We calculate the quantum phase responsible for this effect in\ngraphene--transition metal dichalcogenide bilayers as a function of interlayer\ntwist angle. We show how this quantum phase affects the spin-polarization of\nthe graphene bands and discuss its potential effect on spin-to-charge\nconversion measurements. In twisted trilayers symmetries can be broken as well\nas restored for certain twist angles. This can be used to deduce the effects of\ninduced spin-orbit coupling on spin-lifetime anisotropy and magnetoconductance\nmeasurements."
    },
    {
        "anchor": "Huge negative differential conductance in Au-H2 molecular nanojunctions: Experimental results showing huge negative differential conductance in\ngold-hydrogen molecular nanojunctions are presented. The results are analyzed\nin terms of two-level system (TLS) models: it is shown that a simple TLS model\ncannot produce peaklike structures in the differential conductance curves,\nwhereas an asymmetrically coupled TLS model gives perfect fit to the data. Our\nanalysis implies that the excitation of a bound molecule to a large number of\nenergetically similar loosely bound states is responsible for the peaklike\nstructures. Recent experimental studies showing related features are discussed\nwithin the framework of our model.",
        "positive": "A quantum model of charge capture and release onto/from deep traps: The rapid development of optical technologies and applications revealed the\ncritical role of point defects affecting device performance. One of the\npowerful tools to study influence of defects on charge capture and\nrecombination processes is thermoluminescence. The popular models behind\nthermoluminescence and carrier capture processes are semi-classic though. They\noffer good qualitative description, but implicitly exclude quantum nature of\nthe accompanying parameters, such as frequency factors and capture cross\nsections. As a consequence, results obtained for a specific host material\ncannot be successfully extrapolated to other materials. Thus, the main purpose\nof our work is to introduce a reliable analytical model that describes\nnon-radiative capture and release of electrons from/to the conduction band\n(CB). The proposed model is governed by Bose-Einstein statistics (for phonon\noccupation) and Fermi's golden rule (for resonant charge transfer between the\ntrap and the CB). The constructed model offers a physical interpretation of the\ncapture coefficients and frequency factors, and seamlessly includes the Coulomb\nneutral/attractive nature of traps. It connects the frequency factor to the\noverlap of wavefunctions of the delocalized CB and trap states, and suggests a\nstrong dependence on the density of charge distribution, i.e. the\nionicity/covalency of the chemical bonds within the host. Separation of the\nresonance condition from the accumulation/dissipation of phonons on the site\nleads to the conclusion that the capture cross-section does not necessarily\ndepend on the trap depth. The model is verified by comparison to reported\nexperimental data, showing good agreement. As such, the model generates\nreliable information about trap states whose exact nature is not completely\nunderstood and allows to do materials research in a more systematic way."
    },
    {
        "anchor": "Tuning the electronic transport properties of graphene through\n  functionalisation with fluorine: Engineering the electronic properties of graphene has triggered great\ninterest for potential applications in electronics and opto-electronics. Here\nwe demonstrate the possibility to tune the electronic transport properties of\ngraphene monolayers and multilayers by functionalisation with fluorine. We show\nthat by adjusting the fluorine content different electronic transport regimes\ncan be accessed. For monolayer samples, with increasing the fluorine content,\nwe observe a transition from electronic transport through Mott variable range\nhopping in two dimensions to Efros - Shklovskii variable range hopping.\nMultilayer fluorinated graphene with high concentration of fluorine show\ntwo-dimensional Mott variable range hopping transport, whereas CF0.28\nmultilayer flakes have a band gap of 0.25eV and exhibit thermally activated\ntransport. Our experimental findings demonstrate that the ability to control\nthe degree of functionalisation of graphene is instrumental to engineer\ndifferent electronic properties in graphene materials.",
        "positive": "Gaped graphene bilayer: disorder and magnetic field effects: Double layer graphene is a gapless semiconductor which develops a finite gap\nwhen the layers are placed at different electrostatic potentials. We study,\nwithin the tight-biding approximation, the electronic properties of the gaped\ngraphene bilayer in the presence of disorder, perpendicular magnetic field, and\ntransverse electric field. We show that the gap is rather stable in the\npresence of diagonal disorder. We compute the cyclotron effective mass in the\nsemi-classical approximation, valid at low magnetic fields. Landau level\nformation is clearly seen in zigzag and armchair ribbons of the gaped bilayer\nat intermediate magnetic fields."
    },
    {
        "anchor": "Shot noise of weak cotunneling current: Non-equilibrium\n  fluctuation-dissipation theorem: We study the noise of the cotunneling current through one or several\ntunnel-coupled quantum dots in the Coulomb blockade regime. We consider the\nregime of weak (elastic and inelastic) cotunneling, and prove a non-equilibrium\nfluctuation-dissipation theorem which leads to a universal expression for the\nnoise-to-current ratio (Fano factor).",
        "positive": "Beyond steric selectivity of ions using angstrom-scale capillaries: Ion-selective channels play a key role in physiological processes and are\nused in many technologies. While biological channels can efficiently separate\nsame-charge ions with similar hydration shells, it remains a challenge to mimic\nsuch exquisite selectivity using artificial solid-state channels. Although,\nthere are several nanoporous membranes that show high selectivity with respect\nto certain ions, the underlying mechanisms are based on the hydrated ion size\nand/or charge. There is a need to rationalize the design of artificial channels\nto make them capable of selecting between similar-size same-charge ions, which\nin turn requires understanding of why and how such selectivity can occur. To\naddress this issue, we study angstrom-scale artificial channels made by van der\nWaals assembly, which are comparable in size with typical ions and carry little\nresidual charge on channel walls. This allows us to exclude the first-order\neffects of steric and Coulomb-based exclusion. We show that the studied\ntwo-dimensional angstrom-scale capillaries can distinguish between same-charge\nions with similar hydrated diameters. The selectivity is attributed to\ndifferent positions occupied by ions within the layered structure of\nnanoconfined water, which depend on the ion-core size and differ for anions and\ncations. The revealed mechanism points at possibilities of ion separation\nbeyond the simple steric sieving."
    },
    {
        "anchor": "Energy gap in graphene nanoribbons with structured external electric\n  potentials: The electronic properties of graphene zig-zag nanoribbons with electrostatic\npotentials along the edges are investigated. Using the Dirac-fermion approach,\nwe calculate the energy spectrum of an infinitely long nanoribbon of finite\nwidth $w$, terminated by Dirichlet boundary conditions in the transverse\ndirection. We show that a structured external potential that acts within the\nedge regions of the ribbon, can induce a spectral gap and thus switches the\nnanoribbon from metallic to insulating behavior. The basic mechanism of this\neffect is the selective influence of the external potentials on the spinorial\nwavefunctions that are topological in nature and localized along the boundary\nof the graphene nanoribbon. Within this single particle description, the\nmaximal obtainable energy gap is $E_{\\rm max}\\propto \\pi\\hbar v_{\\rm F}/w$,\ni.e., $\\approx 0.12$\\,eV for $w=$15\\,nm. The stability of the spectral gap\nagainst edge disorder and the effect of disorder on the two-terminal\nconductance is studied numerically within a tight-binding lattice model. We\nfind that the energy gap persists as long as the applied external effective\npotential is larger than $\\simeq 0.55\\times W$, where $W$ is a measure of the\ndisorder strength. We argue that there is a transport gap due to localization\neffects even in the absence of a spectral gap.",
        "positive": "Exact diagonalization study of double quantum dots in parallel geometry\n  in zero-bandwidth limit: Exact eigenstates of the parallel coupled double quantum dots attached to the\nnon-interacting leads taken in zero-bandwidth limit are analytically obtained\nin each particle and spin sector. The ground state of the half-filled system is\nidentified from a four dimensional subspace of the twenty dimensional Hilbert\nspace for different values of tunable parameters of the system viz. the energy\nlevels of the quantum dots, the interdot tunneling matrix-element, the ondot\nand interdot Coulomb interactions and quantities like spin-spin correlation\nbetween the dots, occupancies of the dots are calculated. In the parameter\nspace of the interdot tunneling matrix-element and ondot Coulomb interaction,\nthe dots exhibit both ferromagnetic and antiferromagnetic correlation. There is\na critical dependency of the interdot tunneling matrix-element on the ondot\nCoulomb interaction which leads to transition from the ferromagnetic\ncorrelation to the antiferromagnetic correlation as the interdot tunneling\nmatrix-element is increased. The ferromagnetic and antiferromagnetic\ncorrelations also exist in the absence of interdot tunneling matrix-element\nthrough indirect exchange via the leads. The interdot Coulomb interaction is\nfound to affect this dependency considerably."
    },
    {
        "anchor": "Crossover regimes in lower dimensional structures: Modern growth and fabrication techniques can produce lower dimensional\nstructures in the crossover regime. Such structures in the crossover regime can\nprovide tunability of various properties. For example, a zero-dimensional (0-D)\nstructure evolving towards a 2-D structure shows electronic structure which is\nneither 0-D-like, nor 2-D-like. Within the crossover regime the electronic\ndensity of states (DOS) at Fermi level (Ef) keeps on changing as the size of\nthe system changes. DOS at Ef determines many properties of materials, such as\nelectronic specific heat, spin susceptibility etc. Keeping the importance of\nDOS at Ef in mind, we determine their values and other details of electronic\nstructure of lower dimensional structures of metals, in the 0-D to 1-D, 1-D to\n2-D, 2-D to 3-D, 0-D to 2-D, 0-D to 3-Dand 1-D to 3-Dcrossover regimes, in a\nsimple free electron model. We compare our results with analytical theory and\nexperimental results, wherever available. We also present some results obtained\nby scanning tunneling spectroscopy measurements on Ag islands on Si(111)\nevolving from a 0-D to a 2-D structure. This simple model is quite useful in\nunderstanding lower dimensional structures in the crossover regimes.",
        "positive": "Marginally Self-Averaging One-Dimensional Localization in Bilayer\n  Graphene: The combination of field tunable bandgap, topological edge states, and\nvalleys in the band structure, makes insulating bilayer graphene a unique\nlocalized system, where the scaling laws of dimensionless conductance g remain\nlargely unexplored. Here we show that the relative fluctuations in ln g with\nthe varying chemical potential, in strongly insulating bilayer graphene (BLG)\ndecay nearly logarithmically for channel length up to L/${\\xi}$ ${\\approx}$ 20,\nwhere ${\\xi}$ is the localization length. This 'marginal' self averaging, and\nthe corresponding dependence of <ln g> on L, suggest that transport in strongly\ngapped BLG occurs along strictly one-dimensional channels, where ${\\xi}$\n${\\approx}$ 0.5${\\pm}$0.1 ${\\mu}$m was found to be much longer than that\nexpected from the bulk bandgap. Our experiment reveals a nontrivial\nlocalization mechanism in gapped BLG, governed by transport along robust edge\nmodes."
    },
    {
        "anchor": "Particle Production in Ultra-Strong Coupling Waveguide QED: Understanding large-scale interacting quantum matter requires dealing with\nthe huge number of quanta that are produced by scattering even a few particles\nagainst a complex quantum object. Prominent examples are found from high energy\ncosmic ray showers to the optical or electrical driving of degenerate Fermi\ngases. We tackle this challenge in the context of many-body quantum optics, as\nmotivated by the recent developments of circuit quantum electrodynamics at\nultrastrong coupling. The issue of particle production is addressed\nquantitatively with a simple yet powerful concept rooted in the quantum\nsuperposition principle. This key idea is illustrated by the study of\nmulti-photon emission from a single two-level artificial atom coupled to a high\nimpedance waveguide. We find surprisingly that the off-resonant inelastic\nemission lineshape is dominated by broadband particle production, due to the\nlarge phase space associated with contributions that do not conserve the number\nof excitations. Such frequency conversion processes produce striking signatures\nin time correlation measurements, which can be tested experimentally in quantum\nwaveguides. These ideas open new directions for the simulation of a variety of\nphysical systems, from polaron dynamics in solids to complex superconducting\nquantum architectures.",
        "positive": "Temperature Profile for Ballistic and Diffusive Phonon Transport in a\n  Suspended Membrane with a Radial Symmetric Heat Source: We have calculated the temperature profiles for phonon heat transport in a\nsuspended membrane with a radially symmetric heat source in the two extreme\ncases of either fully ballistic or fully diffusive transport. Theoretical\nresults confirm that it is possible to distinguish these two transport\nmechanisms from the radial temperature profiles alone. Models are also compared\nto experimental data measured with 40 nm thick, free standing silicon nitride\nmembranes below 1 K by using tunnel junction (SINIS) thermometers. The measured\ntemperature profile is qualitatively in agreement with the ballistic model."
    },
    {
        "anchor": "Observation of Van Hove singularities in twisted graphene layers: Electronic instabilities at the crossing of the Fermi energy with a Van Hove\nsingularity in the density of states often lead to new phases of matter such as\nsuperconductivity, magnetism or density waves. However, in most materials this\ncondition is difficult to control. In the case of single-layer graphene, the\nsingularity is too far from the Fermi energy and hence difficult to reach with\nstandard doping and gating techniques. Here we report the observation of\nlow-energy Van Hove singularities in twisted graphene layers seen as two\npronounced peaks in the density of states measured by scanning tunneling\nspectroscopy. We demonstrate that a rotation between stacked graphene layers\ncan generate Van Hove singularities, which can be brought arbitrarily close to\nthe Fermi energy by varying the angle of rotation. This opens intriguing\nprospects for Van Hove singularity engineering of electronic phases.",
        "positive": "Floquet scattering theory for current and heat noise in large amplitude\n  adiabatic pumps: We discuss the statistical correlation properties of currents and energy\nflows generated by an adiabatic quantum pump. Our approach emphasizes the\nimportant role of quantized energy exchange between the sea of electrons and\nthe oscillating scatterer. The pump-frequency introduces a natural energy\nscale. In the low temperature limit, thermal energy much smaller than a\nmodulation quantum, the pump generates a shot-like noise which manifests itself\nin photon-assisted quantum mechanical exchange amplitudes. In the high\ntemperature limit, thermal energy much larger than a modulation quantum, the\npump producesa thermal-like noise due to ac-currents generated by the pump. We\npredict that with increasing temperature the frequency dependence of the noise\nchanges. The current noise is linear in pump-frequency at low temperatures, is\nquadratic at intermediate temperatures, and is linear again at high\ntemperatures. Similarly, in the same temperature regions, the heat flow noise\nis proportional to the third, second and first power of the pump-frequency."
    },
    {
        "anchor": "Influence of the Hall-bar geometry on harmonic Hall voltage measurements\n  of spin-orbit torques: Harmonic Hall voltage measurements are a wide-spread quantitative technique\nfor the measurement of spin-orbit induced effective fields in heavy-metal /\nferromagnet heterostructures. In the vicinity of the voltage pickup lines in\nthe Hall bar, the current is inhomogeneous, which leads to a hitherto not\nquantified reduction of the effective fields and derived quantities, such as\nthe spin Hall angle or the spin Hall conductivity. Here we present a thorough\nanalysis of the influence of the aspect ratio of the voltage pickup lines to\ncurrent channel widths on the apparent spin Hall angle. Experiments were\nperformed with Hall bars with a broad range of aspect ratios and a substantial\nreduction of the apparent spin Hall angle is already seen in Hall crosses with\nan aspect ratio of 1:1. Our experimental results are confirmed by\nfinite-element simulations of the current flow.",
        "positive": "Room Temperature Spin Filtering and Quantum Transport with Transition\n  Metal-Doped Silicon Quantum Dot: Spin filtering is a fundamental operation in spintronics, enabling the\ngeneration and detection of spin-polarized carriers. Here, we proposed and\ntheoretically demonstrated that a 3d transition metal (TM) doped silicon\nquantum dot (SiQD) is a suitable candidate for spin filter device at room\ntemperature. Using density functional theory (DFT), we investigate the\nstructure, electronic properties, and magnetic behavior of TM-SiQD. Our\ncalculations demonstrate that Mn-doped SiQD exhibits the highest stability. The\ndesigned spin-filter device using Mn-doped SiQD shows a spin-filtering\nefficiency of 99.9% at 300K electrode temperature along with very high\nconductance. This remarkable efficiency positions it as a promising candidate\nfor room-temperature spintronic devices."
    },
    {
        "anchor": "Quantum unidirectional magnetoresistance: We predict unidirectional magnetoresistance effects arising in a bilayer\ncomposed of a nonmagnetic metal and a ferromagnetic insulator, whereby both\nlongitudinal and transverse resistances vary when the direction of the applied\nelectric field is reversed or the magnetization of the ferromagnetic layer is\nrotated. In the presence of spin-orbit coupling, an electron wave incident on\nthe interface of the bilayer undergoes a spin rotation and a momentum-dependent\nphase shift. Quantum interference between the incident and reflected waves\nfurnishes the electron with an additional velocity that is even in the in-plane\ncomponent of the electron's wavevector, giving rise to quadratic\nmagnetotransport that is rooted in the wave nature of electrons. The\ncorresponding unidirectional magnetoresistances exhibit decay lengths at the\nscale of the Fermi wavelength$-$distinctive signatures of the quantum nonlinear\nmagnetotransport effect.",
        "positive": "Field-free spin-orbit torque switching of an antiferromagnet with\n  perpendicular N\u00e9el vector: The field-free spin-orbit torque induced 180{\\deg} reorientation of\nperpendicular magnetization is beneficial for the high performance magnetic\nmemory. The antiferromagnetic material (AFM) can provide higher operation speed\nthan the ferromagnetic counterpart. In this paper, we propose a trilayer\nAFM/Insulator/Heavy Metal structure as the AFM memory device. We show that the\nfield-free switching of the AFM with perpendicular N\\'eel vector can be\nachieved by using two orthogonal currents, which provide the uniform\ndamping-like torque and stagger field-like torque, respectively. The reversible\nswitching can be obtained by reversing either current. A current density of\n1.79 10^11A/m^2 is sufficient to induce the switching. In addition, the two\nmagnetic moments become noncollinear during the switching. This enables an\nultrafast switching within 40 picoseconds. The device and switching mechanism\nproposed in this work offer a promising approach to deterministically switch\nthe AFM with perpendicular N\\'eel vector. It can also stimulate the development\nof ultrafast AFM-based MRAM."
    },
    {
        "anchor": "Electron-phonon scattering and in-plane electric conductivity in twisted\n  bilayer graphene: We have surveyed the in-plane transport properties of the graphene twist\nbilayer using (i) a low-energy effective Hamiltonian for the underlying\nelectronic structure, (ii) an isotropic elastic phonon model, and (iii) the\nlinear Boltzmann equation for elastic electron-phonon scattering. We find that\ntransport in the twist bilayer is profoundly sensitive to the rotation angle of\nthe constituent layers. Similar to the electronic structure of the twist\nbilayer the transport is qualitatively different in three distinct angle\nregimes. At large angles ($\\theta > \\,\\approx\\!\\!10^\\circ$) and at temperatures\nbelow an interlayer Bloch-Gr\\\"uneisen temperature of $\\approx 10$~K the\nconductivity is independent of the twist angle i.e. the layers are fully\ndecoupled. Above this temperature the layers, even though decoupled in the\nground state, are re-coupled by electron-phonon scattering and the transport is\ndifferent both from single layer graphene as well as the Bernal bilayer. In the\nsmall angle regime $\\theta <\\,\\approx\\!\\!2^\\circ$ the conductivity drops by two\norders of magnitude and develops a rich energy dependence, reflecting the\ncomplexity of the underlying topological changes (Lifshitz transitions) of the\nFermi surface. At intermediate angles the conductivity decreases continuously\nas the twist angle is reduced, while the energy dependence of the conductivity\npresents two sharp transitions, that occur at specific angle dependent\nenergies, and that may be related to (i) the well studied van Hove singularity\nof the twist bilayer and (ii) a Lifshitz transition that occurs when trigonally\nplaced electron pockets decorate the strongly warped Dirac cone. We examine the\nrole of a layer perpendicular electric field finding that it affects the\nconductivity strongly at low temperatures whereas this effect is washed out by\nFermi smearing at room temperatures.",
        "positive": "Vacancy-induced localized modes and impurity band formation in the\n  Haldane model: a quantum dot analogy: In this study, the Haldane model's edge states are utilized to illustrate\nthat a zero-energy localized state forms around a single vacancy in the model.\nIn order to complete this task, the conventional unit cell associated to the\nHaldane hexagonal structure is transferred onto a two-leg ladder in momentum\nspace, effectively forming an extended Su-Schrieffer-Heeger~(SSH) lattice\nthrough a one-dimensional Fourier transform. Through the application of a\nsuitable unitary transformation, the two-leg SSH ladder in momentum space is\nconverted into an equivalent lattice with two distinct on-site states with\ndifferent momentum that are suitable for the calculations. Ultimately, the\ndesired zero-energy localized mode formed around the vacant-site is represented\nby a combination of the armchair edge states. Furthermore, the scenario\ninvolving two vacant sites is investigated and it is revealed that an effective\nhopping interaction exists between the localized states formed around the\non-site vacancies created along a zigzag chain in the lattice. This structure\ncan be likened to the structure of a quantum dot with two none-degenerate\nenergy levels. Such a hopping interaction is absent for the same vacancies\ncreated on the armchair chains. Finally, it is shown that introducing vacancies\nperiodically on the sites of a zigzag row along a finite-width ribbon with the\nHaldane structure leads to the emergence of an impurity band within the energy\ngap."
    },
    {
        "anchor": "Topological correlations and breaking of fermionic antisymmetry of\n  electrons in FQHE: Highly nonlocal interparticle correlations in quantum Hall states of 2D\ncharged system exposed to the perpendicular strong magnetic field are detailed\nby application of the commensurability condition upon path-integral\nquantization approach and examined by Monte-Carlo Metropolis simulations in\nperfect consistence with exact diagonalization of the Coulomb interaction in\nsmall models and with experimental data. In this way refined filling rate\nhierarchy in the lowest Landau level fully explains the experimentally\ncollected features for FQHE at filling ratios predicted by the conventional\ncomposite fermion model as well as for those beyond the composite fermion model\nbut also visible in the experiment. The trial wave functions for FQHE states\nare proposed using a systematic topological method revealing the different\nsymmetry for different correlated states depending on filling fraction. A\nviolation of fermionic antisymmetry for 2D electrons is evidenced for some\nfilling rates related to specific correlations in FQHE.",
        "positive": "Exploiting the nonlinear impact dynamics of a single-electron shuttle\n  for highly regular current transport: The nanomechanical single-electron shuttle is a resonant system in which a\nsuspended metallic island oscillates between and impacts at two electrodes.\nThis setup holds promise for one-by-one electron transport and the\nestablishment of an absolute current standard. While the charge transported per\noscillation by the nanoscale island will be quantized in the Coulomb blockade\nregime, the frequency of such a shuttle depends sensitively on many parameters,\nleading to drift and noise. Instead of considering the nonlinearities\nintroduced by the impact events as a nuisance, here we propose to exploit the\nresulting nonlinear dynamics to realize a highly precise oscillation frequency\nvia synchronization of the shuttle self-oscillations to an external signal."
    },
    {
        "anchor": "Fine-structure splitting reduction of ionized impurity bound exciton in\n  quantum dot: The ground-state energy and fine-structure splitting of ionized shallow donor\nimpurity-exciton complex in quantum dots are investigated. It is found that\nfine-structure splitting could be largely reduced by the off-center ionized\nimpurities since the anisotropic shape of exciton envelope function is\nsignificantly changed. Anomalous Stark shifts of the ground-state energy and\nefficient tuning of the fine-structure splitting by the external electric field\ndue to the local electric field produced by the ionized impurities are\ndiscussed. The scheme may be useful for the design of the quantum dots-based\nentangled-photon source.",
        "positive": "Supercritical instability in graphene with two charged impurities: We study the supercritical instability in gapped graphene with two charged\nimpurities separated by distance R using the two-dimensional Dirac equation for\nelectron quasiparticles. Attention is paid to a situation when charges of\nimpurities are subcritical, whereas their total charge exceeds a critical one.\nThe critical distance R_{cr} in the system of two charged centers is defined as\nthat at which the electron bound state with the lowest energy reaches the\nboundary of the lower continuum. A variational calculation of the critical\ndistance R_{cr} separating the supercritical (R<R_{cr}) and subcritical\n(R>R_{cr}) regimes is carried out. It is shown that the critical distance\nR_{cr} increases as the quasiparticle gap decreases. The energy and width of a\nquasistationary state as functions of the distance between two impurities are\nderived in the quasiclassical approximation."
    },
    {
        "anchor": "Long-range Fermi sea correlations as the resource for encoding quantum\n  information: An extra constant phase can be added to the wave function of a finite-length\nportion of a chiral Fermi sea. This phase can be read-out with the help of an\nimbalanced interferometer, where such a phase carrier interferes with the\nreference Fermi sea. As a result of such interference, the same in value but\nopposite in sign charge is appeared at interferometer's outputs. A phase\ncarrier consists of electron-hole pairs residing on the surface of the Fermi\nsea. Importantly, these pairs are not only electrically neutral, but in\naddition do not carry heat. A phase carrier can be created, for instance, with\nthe help of an on-demand single-electron source able to produce excitations\nwith a multiple-peak density profile.",
        "positive": "First-Principles Evaluation of the Dzyaloshinskii--Moriya Interaction: We review recent developments of formulations to calculate the\nDzyaloshinskii--Moriya (DM) interaction from first principles. In particular,\nwe focus on three approaches. The first one evaluates the energy change due to\nthe spin twisting by directly calculating the helical spin structure. The\nsecond one employs the spin gauge field technique to perform the derivative\nexpansion with respect to the magnetic moment. This gives a clear picture that\nthe DM interaction can be represented as the spin current in the equilibrium\nwithin the first order of the spin-orbit couplings. The third one is the\nperturbation expansion with respect to the exchange couplings and can be\nunderstood as the extension of the Ruderman--Kittel--Kasuya--Yosida (RKKY)\ninteraction to the noncentrosymmetric spin-orbit systems. By calculating the DM\ninteraction for the typical chiral ferromagnets Mn$_{1-x}$Fe$_x$Ge and\nFe$_{1-x}$Co$_x$Ge, we discuss how these approaches work in actual systems."
    },
    {
        "anchor": "Gap opening in the zeroth Landau level of graphene: We have measured a strong increase of the low-temperature resistivity\n$\\rho_{xx}$ and a zero-value plateau in the Hall conductivity $\\sigma_{xy}$ at\nthe charge neutrality point in graphene subjected to high magnetic fields up to\n30 T. We explain our results by a simple model involving a field dependent\nsplitting of the lowest Landau level of the order of a few Kelvin, as extracted\nfrom activated transport measurements. The model reproduces both the increase\nin $\\rho_{xx}$ and the anomalous $\\nu=0$ plateau in $\\sigma_{xy}$ in terms of\ncoexisting electrons and holes in the same spin-split zero-energy Landau level.",
        "positive": "Quantum lifetime of 2D electron in magnetic field: The lifetime of two dimensional electrons in GaAs quantum wells, placed in\nweak quantizing magnetic fields, is measured using a simple transport method in\nbroad range of temperatures from 0.3 K to 20 K. The temperature variations of\nthe electron lifetime are found to be in good agreement with conventional\ntheory of electron-electron scattering in 2D systems."
    },
    {
        "anchor": "Spin-charge separation in an Aharonov-Bohm interferometer: We study manifestations of spin-charge separation (SCS) in transport through\na tunnel-coupled interacting single-channel quantum ring. We focus on the\nhigh-temperature case (temperature $T$ larger than the level spacing $\\Delta$)\nand discuss both the classical (flux-independent) and interference\ncontributions to the tunneling conductance of the ring in the presence of\nmagnetic flux. We demonstrate that the SCS effects, which arise solely from the\nelectron-electron interaction, lead to the appearance of a peculiar fine\nstructure of the electron spectrum in the ring. Specifically, each level splits\ninto a series of sublevels, with their spacing governed by the interaction\nstrength. In the high-$T$ limit, the envelope of the series contains of the\norder of $T/\\Delta$ sublevels. At the same time, SCS suppresses the tunneling\nwidth of the sublevels by a factor of $\\Delta/T$. As a consequence, the\nclassical transmission through the ring remains unchanged compared to the\nnoninteracting case: the suppression of tunneling is compensated by the\nincrease of the number of tunneling channels. On the other hand, the\nflux-dependent contribution to the conductance depends on the\ninteraction-induced dephasing rate which is known to be parametrically\nincreased by SCS in an infinite system. We show, however, that SCS is not\neffective for dephasing in the limit of weak tunneling. Moreover, generically,\nin the almost closed ring, the dephasing rate does not depend on the\ninteraction strength and is determined by the tunneling coupling to the leads.\nIn certain special symmetric cases, dephasing is further suppressed. Similar to\nthe spinless case, the high-$T$ conductance shows, as a function of magnetic\nflux, a sequence of interaction-induced sharp negative peaks on top of the\nclassical contribution.",
        "positive": "Room temperature nanocavity laser with interlayer excitons in 2D\n  heterostructures: Atomically thin layered two dimensional (2D) material has provided a rich\nlibrary for both fundamental research and device applications. One of the\nspecial advantages is that, bandgap engineering and controlled material\nresponse can be achieved by stacking different 2D materials. Recently several\ntypes of excitonic lasers have been reported based on Transition metal\ndichalcogenide (TMDC) monolayers, however, the emission is still the intrinsic\nenergy bandgap of the monolayers and lasers harnessing the flexibility of Van\nder Waals heterostructures have not been demonstrated yet. Here, we report for\nthe first time a room temperature interlayer exciton laser with MoS2/WSe2\nheterostructures. The onset of lasing action was identified by a combination of\ndistinct kink in the 'L-L' curve and the noticeable collapse of spectral\nlinewidth. Different from visible emission of intralayer excitons for both MoS2\nand WSe2, our interlayer exciton laser works in the infrared range, which is\nfully compatible with the well-established technologies in silicon photonics.\nThanks to the long lifetime of interlayer excitons, the requirement of the\ncavity quality factor is relaxed by orders of magnitude. The demonstration of\nroom temperature interlayer exciton laser might open new perspectives for the\ndevelopment of coherent light source with tailored optical properties on\nsilicon photonics platform."
    },
    {
        "anchor": "Hallmarks of Majorana mode leaking into a hybrid double quantum dot: We investigate the spectral and transport properties of a double quantum dot\nlaterally attached to a topological superconducting nanowire, hosting the\nMajorana zero-energy modes. Specifically, we consider a geometry, in which the\nouter quantum dot is embedded between the external normal and superconducting\nleads, forming a circuit. First, we derive analytical expressions for the bound\nstates in the case of an uncorrelated system and discuss their signatures in\nthe tunneling spectroscopy. Then, we explore the case of strongly correlated\nquantum dots by performing the numerical renormalization group calculations,\nfocusing on the interplay and relationship between the leaking Majorana mode\nand the Kondo states on both quantum dots. Finally, we discuss feasible means\nto experimentally probe the in-gap quasiparticles by using the Andreev\nspectroscopy based on the particle-to-hole scattering mechanism.",
        "positive": "Coupled Mode Theory of Optomechanical Crystals: Acousto-optic interaction in optomechanical crystals allows unidirectional\ncontrol of elastic waves over optical waves. However, as a result of this\nnonlinear interaction, infinitely many optical modes are born. This article\npresents an exact formulaion of coupled mode theory for interaction between\nelastic and photonic Bloch waves moving along an optomechanical waveguide. In\ngeneral, an optical wavefront is strongly diffracted by an elastic wave in\nfrequency and wavevector, and thus infinite modes with different frequencies\nand wavevectors appear. We discuss resonance and mode conversion conditions,\nand present a rigorous method to derive coupling rates and mode profiles. We\nalso find a conservation law which rules over total optical power from\ninteracting individual modes. We present application examples to the theory to\noptomechanical waveguides and cavities, as well as non-reciprocal transmission\nof light and optomechanical switches."
    },
    {
        "anchor": "Magnetic-field asymmetry of nonlinear thermoelectric and heat transport: Nonlinear transport coefficients do not obey, in general, reciprocity\nrelations. We here discuss the magnetic-field asymmetries that arise in\nthermoelectric and heat transport of mesoscopic systems. Based on a scattering\ntheory of weakly nonlinear transport, we analyze the leading-order symmetry\nparameters in terms of the screening potential response to either voltage or\ntemperature shifts. We apply our general results to a quantum Hall antidot\nsystem. Interestingly, we find that certain symmetry parameters show a\ndependence on the measurement configuration.",
        "positive": "Thermopower of a Two-Dimensional Semimetal in a HgTe Quantum Well: The thermopower in a two-dimensional semimetal existing in HgTe quantum wells\n18-21 nm thick has been studied experimentally and theoretically for the first\ntime. It has been found theoretically and experimentally that the thermopower\nhas two components - diffusion and phonon drag and that the second component is\nseveral times larger than the first. It has been concluded that the\nelectron-hole scattering plays an important role in both mechanisms of the\nthermopower."
    },
    {
        "anchor": "In-plane Magnetization Induced Quantum Anomalous Hall Effect: In a two-dimensional electron gas, the quantized Hall conductance can be\ninduced by a strong magnetic field, known as the quantum Hall effect, and it\ncan also result from the strong exchange coupling of magnetic ions, dubbed as\nthe \"quantum anomalous Hall effect\". The quantum Hall effect requires the\nout-of-plane magnetic field, and similarly, it is commonly believed that the\nmagnetization should be out-of-plane for the quantum anomalous Hall effect. In\nthe present work, we find this condition is not necessary and predict that the\nquantum anomalous Hall effect can also be induced by the purely in-plane\nmagnetization in two realistic systems, including Bi$_2$Te$_3$ thin film with\nmagnetic doping and HgMnTe quantum wells with shear strains, when all the\nreflection symmetries are broken. An experimental setup is proposed to confirm\nthis effect, the observation of which will pave the way to search for the\nquantum anomalous Hall effect in a wider range of materials.",
        "positive": "Tenfold Topology of Crystals: Unified classification of crystalline\n  topological insulators and superconductors: The celebrated tenfold-way of Altland-Zirnbauer symmetry classes discern any\nquantum system by its pattern of non-spatial symmetries. It lays at the core of\nthe periodic table of topological insulators and superconductors which provided\na complete classification of weakly-interacting electrons' non-crystalline\ntopological phases for all symmetry classes. Over recent years, a plethora of\ntopological phenomena with diverse surface states has been discovered in\ncrystalline materials. In this paper, we obtain an exhaustive classification of\ntopologically distinct groundstates as well as topological phases with\nanomalous surface states of crystalline topological insulators and\nsuperconductors for key space-groups, layer-groups, and rod-groups. This is\ndone in a unified manner for the full tenfold-way of Altland-Zirnbauer\nnon-spatial symmetry classes. We establish a comprehensive paradigm that\nharnesses the modern mathematical framework of equivariant spectra; it allows\nus to obtain results applicable to generic topological classification problems.\nIn particular, this paradigm provides efficient computational tools that enable\nan inherently unified treatment of the full tenfold-way."
    },
    {
        "anchor": "Non-Hermitian Majorana modes protect degenerate steady states: We introduce non-Hermitian generalizations of Majorana zero modes (MZMs)\nwhich appear in the topological phase of a weakly dissipative Kitaev chain\ncoupled to a Markovian bath. Notably, the presence of MZMs ensures that the\nsteady state in the absence of decoherence events is two-fold degenerate.\nWithin a stochastic wavefunction approach, the effective Hamiltonian governing\nthe coherent, non-unitary dynamics retains BDI classification of the closed\nlimit, but belongs to one of four non-Hermitian \"flavors\" of the ten-fold way.\nWe argue for the stability of MZMs due to a generalization of particle-hole\nsymmetry, and uncover the resulting topological phase diagram. Qualitative\nfeatures of our study generalize to two-dimensional chiral superconductors. The\ndissipative superconducting chain can be mapped to an Ising model in a complex\ntransverse field, and we discuss potential signatures of the degeneracy.",
        "positive": "Propagation of Time-Nonlocal Quantum Master Equations for Time-Dependent\n  Electron Transport: Time-resolved electron transport in nano-devices is described by means of a\ntime-nonlocal quantum master equation for the reduced density operator. Our\nformulation allows for arbitrary time dependences of any device or contact\nparameter. The quantum master equation and the related expression for the\nelectron current through the device are derived in fourth order of the coupling\nto the contacts. It is shown that a consistent sum up to infinite orders\ninduces level broadening in the device. To facilitate a numerical propagation\nof the equations we propose to use auxiliary density operators. An expansion of\nthe Fermi function in terms of a sum of simple poles leads to a set of\nequations of motion, which can be solved by standard methods. We demonstrate\nthe viability of the proposed propagation scheme and consider electron\ntransport through a double quantum dot."
    },
    {
        "anchor": "Broadband ferromagnetic resonance characterization of GaMnAs thin films: The precessional magnetization dynamics of GaMnAs thin films are\ncharacterized by broadband network analyzer ferromagnetic resonance (FMR) in a\ncoplanar geometry at cryogenic temperatures. The FMR frequencies are\ncharacterized as function of in-plane field angle and field amplitude. Using an\nextended Kittel model of the FMR dispersion the magnetic film parameters such\nas saturation magnetization and anisotropies are derived. The modification of\nthe FMR behavior and of the magnetic parameters of the thin film upon annealing\nis analyzed.",
        "positive": "Spin Orbit Torque on a Curved Surface: We provide a general formulation of the spin-orbit coupling on a 2D curved\nsurface. Considering the wide applicability of spin-orbit effect in\nspinor-based condensed matter physics, a general spin-orbit formulation could\naid the study of spintronics, Dirac graphene, topological systems, and quantum\ninformation on curved surfaces. Particular attention is then devoted to the\ndevelopment of an important spin-orbit quantity known as the spin-orbit torque.\nAs devices trend smaller in dimension, the physics of local geometries on\nspin-orbit torque, hence spin and magnetic dynamics shall not be neglected. We\nderived the general expression of a spin-orbit anisotropy field for the curved\nsurfaces and provided explicit solutions in the special contexts of the\nspherical, cylindrical and flat coordinates. Our expressions allow spin-orbit\nanisotropy fields and hence spin-orbit torque to be computed over the entire\nsurfaces of devices of any geometry."
    },
    {
        "anchor": "Quantized charge fractionalization at quantum Hall Y junctions in the\n  disorder-dominated regime: Fractionalization is a phenomenon where an elementary excitation partitions\ninto several pieces. This picture explains non-trivial transport through a\njunction of one-dimensional edge channels defined by topologically distinct\nquantum Hall states, for example, a hole-conjugate state at Landau-level\nfilling factor $\\nu$ = 2/3. Here we employ a time-resolved scheme to identify\nan elementary fractionalization process; injection of charge q from a\nnon-interaction region into an interacting and scattering region of\none-dimensional channels results in the formation of a collective excitation\nwith charge $(1-\\textit{r})\\textit{q}$ by reflecting fractionalized charge\n$\\textit{rq}$. The fractionalization factors, $\\textit{r}$ = 0.34$\\pm$0.03 for\n$\\nu$ = 2/3 and $\\textit{r}$ = 0.49$\\pm$0.03 for $\\nu$ = 2, are consistent with\nthe quantized values of 1/3 and 1/2, respectively, which are expected in the\ndisorder dominated regime. The scheme can be used for generating and\ntransporting fractionalized charges with a well-defined time course along a\nwell-defined path.",
        "positive": "Suppressing phonon transport in nanowires: a simple model for\n  phonon-surface roughness interaction: Suppressing phonon propagation in nanowires is an essential goal towards\nachieving efficient thermoelectric devices. Recent experiments have shown\nunambiguously that surface roughness is a key factor that can reduce the\nthermal conductivity well below the Casimir limit in thin crystalline silicon\nnanowires. We use insights gained from the experimental studies to construct a\nsimple analytically tractable model of the phonon-surface roughness interaction\nthat provides a better theoretical understanding of the effects of surface\nroughness on the thermal conductivity, which could potentially help in\ndesigning better thermoelectric devices."
    },
    {
        "anchor": "Non-perturbative laser effects on the electrical properties of graphene\n  nanoribbons: The use of Floquet theory combined with a realistic description of the\nelectronic structure of illuminated graphene and graphene nanoribbons is\ndeveloped to assess the emergence of non-adiabatic and non-perturbative effects\non the electronic properties. Here, we introduce an efficient computational\nscheme and illustrate its use by applying it to graphene nanoribbons in the\npresence of both linear and circular polarization. The interplay between\nconfinement due to the finite sample size and laser-induced transitions is\nshown to lead to sharp features on the average conductance and density of\nstates. Particular emphasis is given to the emergence of the bulk limit\nresponse.",
        "positive": "Dispersive cavity-mediated quantum gate between driven dot-donor nuclear\n  spins: Nuclear spins show exceptionally long coherence times but the underlying good\nisolation from their environment is a challenge when it comes to controlling\nnuclear spin qubits. A particular difficulty, not only for nuclear spin qubits,\nis the realization of two-qubit gates between distant qubits. Recently, strong\ncoupling between an electron spin and microwave resonator photons as well as a\nmicrowave resonator mediated coupling between two electron spins both in the\nresonant and the dispersive regime have been reported and, thus, a microwave\nresonator mediated electron spin two qubit gate seems to be in reach. Inspired\nby these findings, we theoretically investigate the interaction of a microwave\nresonator with a hybrid quantum dot-donor (QDD) system consisting of a gate\ndefined Si QD and a laterally displaced $^{31}$P phosphorous donor atom\nimplanted in the Si host material. We find that driving the QDD system allows\nto compensate the frequency mismatch between the donor nuclear spin splitting\nin the MHz regime and typical superconducting resonator frequencies in the GHz\nregime, and also enables an effective nuclear spin-photon coupling. While we\nexpect this coupling to be weak, we predict that coupling the nuclear spins of\ntwo distant QDD systems dispersively to the microwave resonator allows the\nimplementation of a resonator mediated nuclear spin two-qubit\n$\\sqrt{i\\mathrm{SWAP}}$ gate with a gate fidelity approaching $90\\%$."
    },
    {
        "anchor": "Quantum coherent control of a hybrid superconducting circuit made with\n  graphene-based van der Waals heterostructures: Quantum coherence and control is foundational to the science and engineering\nof quantum systems. In van der Waals (vdW) materials, the collective coherent\nbehavior of carriers has been probed successfully by transport measurements.\nHowever, temporal coherence and control, as exemplified by manipulating a\nsingle quantum degree of freedom, remains to be verified. Here we demonstrate\nsuch coherence and control of a superconducting circuit incorporating\ngraphene-based Josephson junctions. Furthermore, we show that this device can\nbe operated as a voltage-tunable transmon qubit, whose spectrum reflects the\nelectronic properties of massless Dirac fermions traveling ballistically. In\naddition to the potential for advancing extensible quantum computing\ntechnology, our results represent a new approach to studying vdW materials\nusing microwave photons in coherent quantum circuits.",
        "positive": "Modulated Kondo screening along magnetic mirror twin boundaries in\n  monolayer MoS2 on graphene: A many-body resonance emerges at the Fermi energy when an electron bath\nscreens the magnetic moment of a half-filled impurity level. This Kondo effect,\noriginally introduced to explain the abnormal resistivity behavior in bulk\nmagnetic alloys, has been realized in many quantum systems over the past\ndecades, such as quantum dots, quantum point contacts, nanowires,\nsingle-molecule transistors, heavy-fermion lattices, down to adsorbed single\natoms. Here we describe a unique Kondo system which allows us to experimentally\nresolve the spectral function consisting of impurity levels and Kondo resonance\nin a large Kondo temperature range, as well as their spatial modulation. Our\nexperimental Kondo system, based on a discrete half-filled quantum confined\nstate within a MoS2 grain boundary, in conjunction with numerical\nrenormalization group calculations, enables us to test the predictive power of\nthe Anderson model which is the basis of the microscopic understanding of Kondo\nphysics."
    },
    {
        "anchor": "Fluctuations of the Electromagnetic Local Density of States as a Probe\n  for Structural Phase Switching: We study the statistics of the fluorescence decay rates for single quantum\nemitters embedded in a scattering medium undergoing a phase transition. Under\ncertain circumstances, the structural properties of the scattering medium\nexplore a regime in which the system dynamically switches between two different\nphases. While in that regime the light scattering properties of both phases are\nhardly distinguishable, we demonstrate that the lifetime statistics of single\nemitters with low diffusivity is clearly dependent on the dynamical state in\nwhich the medium evolves. Hence, lifetime statistics provides clear signatures\nof phase switching in systems where light scattering does not.",
        "positive": "Cotunneling effects in GaAs vertical double quantum dot: We observed lifting of Coulomb blockade in GaAs vertical double quantum dot\nwith low potential barriers, induced by cotunneling mechanisms at dilution\nfridge temperature of 10 mK. Several distinct features were observed, compared\nto single dot case, and appropriate explanation for them was given"
    },
    {
        "anchor": "Spin transfer nano-oscillators: The use of spin transfer nano-oscillators (STNOs) to generate microwave\nsignal in nanoscale devices have aroused tremendous and continuous research\ninterest in recent years. Their key features are frequency tunability,\nnanoscale size, broad working temperature, and easy integration with standard\nsilicon technology. In this feature article, we give an overview of recent\ndevelopments and breakthroughs in the materials, geometry design and properties\nof STNOs. We focus in more depth on our latest advances in STNOs with\nperpendicular anisotropy showing a way to improve the output power of STNO\ntowards the {\\mu}W range. Challenges and perspectives of the STNOs that might\nbe productive topics for future research were also briefly discussed.",
        "positive": "Anomalous photon thermal Hall effect: We predict an anomalous thermal Hall effect (ATHE) mediated by photons in\nnetworks of Weyl semi-metals. Contrary to the photon thermal Hall effect in\nmagneto-optical systems which requires the application of an external magnetic\nfield the ATHE in a Weyl semi-metals network is an intrinsic property of these\nsystems. Since the Weyl semi-metals can exhibit a strong nonreciprocal response\nin the infrared over a broad spectral range the magnitude of thermal Hall flux\nin these systems can be relatively large compared to the primary flux. This\nATHE paves the way for a directional control of heat flux by localy tuning the\nmagnitude of temperature field without changing the direction of temperature\ngradient."
    },
    {
        "anchor": "Chiral anomaly, dimensional reduction, and magnetoresistivity of Weyl\n  and Dirac semimetals: By making use of the Kubo formula, we calculate the conductivity of Dirac and\nWeyl semimetals in a magnetic field. We find that the longitudinal (along the\ndirection of the magnetic field) magnetoresistivity is negative at sufficiently\nlarge magnetic fields for {\\it both} Dirac and Weyl semimetals. The physical\nreason of this phenomenon is intimately connected with the dimensional spatial\nreduction $3 \\to 1$ in the dynamics of the lowest Landau level. The\noff-diagonal component of the transverse (with respect to the direction of the\nmagnetic field) conductivity in Weyl semimetals contains an anomalous\ncontribution directly proportional to the momentum space separation between the\nWeyl nodes. This contribution comes exclusively from the lowest Landau level\nand, as expected, is independent of the temperature, chemical potential, and\nmagnetic field. The other part of the off-diagonal conductivity is the same as\nin Dirac semimetals and is connected with a nonzero density of charge carriers.\nThe signatures for experimental distinguishing Weyl semimetals from Dirac ones\nthrough the measurements of conductivity are discussed.",
        "positive": "Tracking the energies of one-dimensional subband edges in quantum point\n  contacts using dc conductance measurements: The semiconductor quantum point contact has long been a focal point for\nstudies of one-dimensional electron transport. Their electrical properties are\ntypically studied using ac conductance methods, but recent work has shown that\nthe dc conductance can be used to obtain additional information, with a\ndensity-dependent Land\\'{e} effective g-factor recently reported [T.-M. Chen et\nal, Phys. Rev. B 79, 081301 (2009)]. We discuss previous dc conductance\nmeasurements of quantum point contacts, demonstrating how valuable additional\ninformation can be extracted from the data. We provide a comprehensive and\ngeneral framework for dc conductance measurements that provides a path to\nimproving the accuracy of existing data and obtaining useful additional data. A\nkey aspect is that dc conductance measurements can be used to map the energy of\nthe 1D subband edges directly, giving new insight into the physics that takes\nplace as the spin-split 1D subbands populate. Through a re-analysis of the data\nobtained by Chen et al, we obtain two findings. The first is that the 2-down\nsubband edge closely tracks the source chemical potential when it first begins\npopulating before dropping more rapidly in energy. The second is that the 2-up\nsubband populates more rapidly as the subband edge approaches the drain\npotential. This second finding suggests that the spin-gap may stop opening, or\neven begin to close again, as the 2-up subband continues populating, consistent\nwith recent theoretical calculations and experimental studies."
    },
    {
        "anchor": "Mesoscopic versus Macroscopic division of current fluctuations: We investigate the current shot noise at a three terminal node in which one\nof the branches contains a noise generating source and the correlations are\nmeasured between the currents flowing through the other two branches.\nInterestingly, if the node is macroscopic, the current correlations are\npositive, whereas for a quantum coherent mesoscopic node anti-bunching of\nelectrons leads to negative correlations. We present specific predictions which\npermit the experimental investigation of the crossover from quantum mechanical\nnoise division to macroscopic noise noise division.",
        "positive": "Twist Mode in Spherical Alkali Metal Clusters: A remarkable orbital quadrupole magnetic resonance, so-called twist mode, is\npredicted in alkali metal clusters where it is represented by $I^{\\pi}=2^-$\nlow-energy excitations of valence electrons with strong M2 transitions to the\nground state. We treat the twist by both macroscopic and microscopic ways. In\nthe latter case, the shell structure of clusters is fully exploited, which is\ncrucial for the considered size region ($8\\le N_e\\le 1314$). The\nenergy-weighted sum rule is derived for the pseudo-Hamiltonian. In medium and\nheavy spherical clusters the twist dominates over its spin-dipole counterpart\nand becomes the most strong multipole magnetic mode."
    },
    {
        "anchor": "Heat vortexes of ballistic, diffusive and hydrodynamic phonon transport\n  in two-dimensional materials: In this work, the heat vortexes in two-dimensional porous or ribbon\nstructures are investigated based on the phonon Boltzmann transport equation\n(BTE) under the Callaway model. First, the separate thermal effects of normal\n(N) scattering and resistive (R) scattering are investigated with\nfrequency-independent assumptions. And then the heat vortexes in graphene are\nstudied as a specific example. It is found that the heat vortexes can appear in\nboth ballistic (rare R/N scattering) and hydrodynamic (N scattering dominates)\nregimes but disappear in the diffusive (R scattering dominates) regime. As long\nas there is not sufficient R scattering, the heat vortexes can appear in\npresent simulations.",
        "positive": "Emergence of a low-energy excitonic state in single layer WS2 with 1H/1T\n  phase mixture: Transition metal dichalcogenides possess a unique combination of properties\nthat make them a malleable platform to study and engineer light-matter\ninteractions. On one hand, monolayers of WS2 naturally occur in the\nsemiconducting 1H phase whose optical properties are dominated by excitons\nemerging from the band edges at the K valley. On the other hand, the 1T phase\nexhibits metallic properties and can be triggered by weak external stimuli.\nHere we use plasma irradiation to engineer a 1H/1T mixed phase state in WS2 and\ncontrol the grain size of the 1T patches by tuning the irradiation time. We\nshow that in the mixed phase WS2 a band nesting effect gives rise to new\ncritical points resulting in a low-energy excitonic transition below the A\nexciton. Compared to standard excitons in WS2, this new resonance shows larger\nabsorption and longer lifetime. The combination of these properties suggests\nnew concepts for exciton-based optoelectronic devices that could stem from the\ncontrol of phase mixture states in two-dimensional semiconductors."
    },
    {
        "anchor": "Ballistic interferences in suspended graphene: Graphene is a 2-dimensional (2D) carbon allotrope with the atoms arranged in\na honeycomb lattice. The low-energy electronic excitations in this 2D crystal\nare described by massless Dirac fermions that have a linear dispersion relation\nsimilar to photons. Taking advantage of this optics-like electron dynamics,\ngeneric optical elements like lenses, beam splitters and wave guides have been\nproposed for electrons in engineered ballistic graphene. Tuning of these\nelements relies on the ability to adjust the carrier concentration in defined\nareas, including the possibility to create bipolar regions of opposite charge\n(p-n regions). However, the combination of ballistic transport and complex\nelectrostatic gating remains challenging. Here, we report on the fabrication\nand characterization of fully suspended graphene p-n junctions. By local\nelectro-static gating, resonant cavities can be defined, leading to complex\nFabry-Perot interference patterns in the unipolar and the bipolar regime. The\namplitude of the observed conductance oscillations accounts for quantum\ninterference of electrons that propagate ballistically over long distances\nexceeding 1 micron. We also demonstrate that the visibility of the interference\npattern is enhanced by Klein collimation at the p-n interface. This finding\npaves the way to more complex gate-controlled ballistic graphene devices and\nbrings electron optics in graphene closer to reality.",
        "positive": "Space charge and screening of a supercritical impurity cluster in\n  monolayer graphene: Coulomb impurity of charge $Ze$ is known to destabilize the ground state of\nundoped graphene with respect to creation of screening space charge if $Z$\nexceeds a critical value of $1/2\\alpha$ set by material's fine structure\nconstant $\\alpha$. Recent experimental advances made it possible to explore\nthis transition in a controlled manner by tuning $Z$ across the critical point.\nCombined with relatively large value of $\\alpha$ this opens a possibility to\nstudy graphene's screening response to a supercritical impurity $Z\\alpha\\gg1$\nwhen the screening charge is large, and the Thomas-Fermi analysis, that we\nrevisit, is adequate. The character of screening in this regime is controlled\nby the dimensionless screening parameter $Z\\alpha^{2}$. Specifically, for\ncircular impurity cluster most of the screening charge in the weak-screening\nregime $Z\\alpha^{2}\\ll1$ is found to reside outside the cluster. The\nstrong-screening regime $Z\\alpha^{2}\\gg1$ provides a realization of the Thomson\natom: most of the screening charge is inside the cluster nearly perfectly\nneutralizing the source charge with the exception of a transition layer near\ncluster's edge where the rest of the space charge is localized."
    },
    {
        "anchor": "Schottky-barrier double-walled carbon nanotube field-effect transistors: We investigate electronic transport properties of Schottky-barrier\nfield-effect transistors (FET) based on double-walled carbon nanotubes (DWNT)\nwith a semiconducting outer shell and a metallic inner one. These kind of\nDWNT-FET show asymmetries of the $I$-$V$ characteristics and threshold voltages\ndue to the electron-hole asymmetry of the Schottky barrier. The presence of the\nmetallic inner shell induces a large effective band gap, which is one order of\nmagnitude larger than that due to the semiconducting shell alone of a\nsingle-walled carbon nanotube FET.",
        "positive": "Level-spectra Statistics in Planar Fractal Tight-Binding Models: In this communication, we study the level-spectra statistics when a\nnoninteracting electron gas is confined in \\textit{Sierpi\\'{n}ski Carpet}\n(\\textit{SC}) lattices. These \\textit{SC} lattices are constructed under two\nrepresentative patterns of the $self$ and $gene$ patterns, and classified into\ntwo subclass lattices by the area-perimeter scaling law. By the singularly\ncontinuous spectra and critical traits using two level-statistic tools\\iffalse\nthe nearest spacing distribution and alternative gap-ratio distribution\\fi, we\nascertain that both obey the critical phase due to broken translation symmetry\nand the long-range order of scaling symmetry. The Wigner-like conjecture is\nconfirmed numerically since both belong to the Gaussian orthogonal ensemble. An\nanalogy was observed in a quasiperiodic lattice~\\cite{Zhong1998Level}. In\naddition, this critical phase isolates the crucial behavior near the\nmetal-insulator transition edge in Anderson model. The lattice topology of the\nself-similarity feature can induce level clustering behavior."
    },
    {
        "anchor": "Optical chiral properties in a large resonant hybrid photonic cluster: Optical chiral properties of a resonant hybrid photonic crystal (RHPC) are\ncomputed taking into account spin-orbit effect due to light-hole excitons\nperfectly confined in 2D quantum wells. The trends of the optical activity,\nexpressed as a ratio between the absorption intensities of the z and xy\nlight-hole polaritons, are obtained by computing the optical response in a\nrather large N-cluster of elementary cells (N= 34) and for exciton energy, in\nresonance with a stationery inflection point (SIP). High values of spin-orbit\ninteraction (0.7 eV A) produce strong distortions of the optical activity polar\ncurves that, differently, becomes rather isotropic if the experimental value\n(0.14 eV A) is used.",
        "positive": "Thomas-Fermi-Dirac-von Weizsacker hydrodynamics in laterally modulated\n  electronic systems: We have studied the collective plasma excitations of a two-dimensional\nelectron gas with an arbitrary lateral charge-density modulation. The dynamics\nis formulated using a previously developed hydrodynamic theory based on the\nThomas-Fermi-Dirac-von Weizsacker approximation. In this approach, both the\nequilibrium and dynamical properties of the periodically modulated electron gas\nare treated in a consistent fashion. We pay particular attention to the\nevolution of the collective excitations as the system undergoes the transition\nfrom the ideal two-dimensional limit to the highly-localized one-dimensional\nlimit. We also calculate the power absorption in the long-wavelength limit to\nillustrate the effect of the modulation on the modes probed by far-infrared\n(FIR) transmission spectroscopy."
    },
    {
        "anchor": "Electric-field tunable Dirac semimetal state in phosphorene thin films: We study the electric-field tunable electronic properties of phosphorene thin\nfilms, using the framework of density functional theory. We show that\nphosphorene thin films offer a versatile material platform to study two\ndimensional Dirac fermions on application of a transverse electric field.\nIncreasing the strength of the transverse electric field beyond a certain\ncritical value in phosphorene leads to the formation of two symmetry protected\ngapless Dirac fermions states with anisotropic energy dispersion. The\nspin-orbit coupling splits each of these Dirac state into two spin- polarized\nDirac cones which are also protected by non-symmorphic crystal symmetries. Our\nstudy shows that the position as well as the carrier velocity of the spin\npolarized Dirac cone states can be controlled by the strength of the external\nelectric field.",
        "positive": "Disordered double Weyl node: Comparison of transport and\n  density-of-states calculations: Double Weyl nodes are topologically protected band crossing points which\ncarry chiral charge $\\pm2$. They are stabilized by $C_{4}$ point group symmetry\nand are predicted to occur in $\\mathrm{SrSi_{2}}$ or $\\mathrm{HgCr_{2}Se_{4}}$.\nWe study their stability and physical properties in the presence of a disorder\npotential. We investigate the density of states and the quantum transport\nproperties at the nodal point. We find that, in contrast to their counterparts\nwith unit chiral charge, double Weyl nodes are unstable to any finite amount of\ndisorder and give rise to a diffusive phase, in agreement with predictions of\nGoswami and Nevidomskyy [Phys. Rev. B 92, 214504 (2015)] and Bera, Sau, and Roy\n[Phys. Rev. B 93, 201302(R) (2016)]. However, for finite system sizes a\ncrossover between pseudodiffusive and diffusive quantum transport can be\nobserved."
    },
    {
        "anchor": "Damping and Anti-Damping Phenomena in Metallic Antiferromagnets: An\n  ab-initio Study: We report on a first principles study of anti-ferromagnetic resonance (AFMR)\nphenomena in metallic systems [MnX (X=Ir,Pt,Pd,Rh) and FeRh] under an external\nelectric field. We demonstrate that the AFMR linewidth can be separated into a\nrelativistic component originating from the angular momentum transfer between\nthe collinear AFM subsystem and the crystal through the spin orbit coupling\n(SOC), and an exchange component that originates from the spin exchange between\nthe two sublattices. The calculations reveal that the latter component becomes\nsignificant in the low temperature regime. Furthermore, we present results for\nthe current-induced intersublattice torque which can be separated into the\nField-Like (FL) and Damping-Like (DL) components, affecting the intersublattice\nexchange coupling and AFMR linewidth, respectively.",
        "positive": "Dirac-Source Diode with Sub-unity Ideality Factor: An increase in power consumption necessitates a low-power circuit technology\nto extend Moore's law. Low-power transistors, such as tunnel field-effect\ntransistors (TFETs), negative-capacitance field-effect transistors (NC-FETs),\nand Dirac-source field-effect transistors (DS-FETs), have been realised to\nbreak the thermionic limit of the subthreshold swing (SS). However, a low-power\ndiode rectifier, which breaks the thermionic limit of an ideality factor (n) of\n1 at room temperature, has not been proposed yet. In this study, we have\nrealised a DS Schottky diode, which exhibits a steep-slope characteristic\ncurve, by utilising the linear density of states (DOSs) of graphene. For the\ndeveloped DS Schottky diode, n<1 for more than two decades of drain current\nwith a minimum value of 0.8, and the rectifying ratio is large (100000). The\nrealisation of a DS Schottky diode paves the way for the development of\nlow-power electronic circuits."
    },
    {
        "anchor": "Symmetric Wannier states and tight-binding model for quantum spin Hall\n  bands in AB-stacked MoTe$_2$/WSe$_2$: Motivated by the observation of topological states in AB-stacked\nMoTe$_2$/WSe$_2$, we construct the symmetry-adapted Wannier states and\ntight-binding model for the quantum spin Hall bands in this system. Our\nconstruction is based on the symmetry analysis of Bloch states obtained from\nthe continuum moir\\'e Hamiltonian. For model parameters extracted from\nfirst-principles calculations, we find that the quantum spin Hall bands can be\ndescribed by a tight-binding model defined on a triangular lattice. There are\ntwo Wannier states per valley, which have the same Wannier center but different\nangular momenta under threefold rotation. The tight-binding model not only\nreproduces the energy spectrum, but also accurately describes the topological\nphase transition induced by the out-of-plane displacement field. Our study\nsheds new light on the topological states in moir\\'e transition metal\ndichalcogenides bilayers, and provides a route to addressing the many-body\nphysics in AB-stacked MoTe$_2$/WSe$_2$.",
        "positive": "From nanoscale to macroscale: applications of nanotechnology to\n  production of bulk ultra-strong materials: Carbon nanotubes have been famous since their discovery twenty years ago for\ntheir remarkable physical properties, from strength a hundred times higher than\nsteel, to electrical current capacity a 1,000 times higher than copper. But so\nfar they have only been produced at most up to centimeter lengths.\n  Here are presented some proposals to combine the nanotubes in such a way to\nget arbitrarily long lengths while maintaining their extraordinary physical\nproperties."
    },
    {
        "anchor": "Current-Driven Domain Wall Depinning and Propagation in Notched\n  Nanowires: Adiabatic spin transfer torque induced domain wall (DW) depinning from a\nnotch and DW propagation in a nanowire with a series of notches is\ninvestigated. Surprisingly, notches help a current to depin a DW and make a DW\neasier to propagate along a wire. Following fascinating results on DW dynamics\nare found. 1) The depinning current density of a DW in a notch is substantially\nlower than the intrinsic threshold value below which a sustainable DW\npropagation doesn't exist in a homogeneous wire. 2) The DW displacement from a\nnotch is insensitive to notch geometry and current density when it is between\nthe depinning and the intrinsic threshold current density. 3) A current density\nbelow the intrinsic threshold value can induce a sustainable DW propagation\nalong notched nanowires. These findings not only reveal interesting and\ncomplicated interaction between a current and a DW, but also have profound\nimplications in our current understanding of current-driven DW dynamics as well\nas in the design of spintronic devices.",
        "positive": "Helical Symmetry Breaking and Quantum Anomaly in Massive Dirac Fermions: Helical symmetry of massive Dirac fermions is broken explicitly in the\npresence of electric and magnetic fields. Here we present two equations for the\ndivergence of helical and axial-vector currents following the Jackiw-Johnson\napproach to the anomaly of the neutral axial vector current. We discover the\ncontribution from the helical symmetry breaking is attributed to the occupancy\nof the two states at the top of the valence band and the bottom of the\nconduction band. The explicit symmetry breaking fully cancels the anomalous\ncorrection from the quantum fluctuation in the band gap. The chiral anomaly can\nbe derived from the helical symmetry breaking. It provides an alternative route\nto understand the chiral anomaly from the point of view of the helical symmetry\nbreaking. The pertinent physical consequences in condensed matter are the\nhelical magnetic effect which means a charge current circulating at the\ndirection of the magnetic field, and the mass-dependent positive longitudinal\nmagnetoconductivity as a transport signature. The discovery not only reflects\nanomalous magneto-transport properties of massive Dirac materials but also\nreveals the close relation between the helical symmetry breaking and the\nphysics of chiral anomaly in quantum field theory and high energy physics."
    },
    {
        "anchor": "Metal nanofilm in strong ultrafast optical fields: We predict that a metal nanofilm subjected to an ultrashort (single\noscillation) optical pulse of a high field amplitude $\\sim 3 \\mathrm{V/\\AA}$ at\nnormal incidence undergoes an ultrafast (at subcycle times $\\lesssim 1\n\\mathrm{fs}$) transition to a state resembling semimetal. Its reflectivity is\ngreatly reduced, while the transmissivity and the optical field inside the\nmetal are greatly increased. The temporal profiles of the optical fields are\npredicted to exhibit pronounced subcycle oscillations, which are attributed to\nthe Bloch oscillations and formation of the Wannier-Stark ladder of electronic\nstates. The reflected, transmitted, and inside-the-metal pulses have non-zero\nareas approaching half-cycle pulses. The effects predicted are promising for\napplications to nanoplasmonic modulators and field-effect transistors with\npetahertz bandwidth.",
        "positive": "Supersymmetric non-Hermitian topological interface laser: We investigate laser emission at the interface of a topological and trivial\nphases with loss and gain. The system is described by a Su-Schrieffer-Heeger\nmodel with site-dependent hopping parameters. We study numerically and\nanalytically the interface states. The ground state is described by the\nJackiw-Rebbi mode with a pure imaginary energy, reflecting the non-Hermiticity\nof the system. It is strictly localized only at the A sites. We also find a\nseries of analytic solutions of excited states based on SUSY quantum mechanics,\nwhere the A and B sites of the bipartite lattice form SUSY partners. We then\nstudy the system containing loss and gain with saturation. The Jackiw-Rebbi\nmode is extended to a nonlinear theory, where B sites are also excited. The\nrelative phases between A and B sites are fixed, and hence it will serve as a\nlarge area coherent laser."
    },
    {
        "anchor": "Anomalous fractal scaling in two-dimensional electric networks: Much of the qualitative nature of physical systems can be predicted from the\nway it scales with system size. Contrary to the continuum expectation, we\nobserve a profound deviation from logarithmic scaling in the impedance of a\ntwo-dimensional $LC$ circuit network. We find this anomalous impedance\ncontribution to sensitively depend on the number of nodes $N$ in a curious\nerratic manner, and experimentally demonstrate its robustness against\nperturbations from the contact and parasitic impedance of individual\ncomponents. This impedance anomaly is traced back to a generalized resonance\ncondition reminiscent of the Harper's equation for electronic lattice transport\nin a magnetic field, even though our circuit network does not involve magnetic\ntranslation symmetry. It exhibits an emergent fractal parametric structure of\nanomalous impedance peaks for different $N$ that cannot be reconciled with\ncontinuum theory and does not correspond to regular waveguide resonant\nbehavior. This anomalous fractal scaling extends to the transport properties of\ngeneric systems described by a network Laplacian whenever a resonance frequency\nscale is simultaneously present.",
        "positive": "Cooper pair splitting in a nanoSQUID geometry at high transparency: We describe a Josephson device composed of two superconductors separated by\ntwo interacting quantum dots in parallel, as a probe for Cooper pair splitting.\nIn addition to sequential tunneling of electrons through each dot, an\nadditional transport channel exists in this system: crossed Andreev reflection,\nwhere a Cooper pair from the source is split between the two dots and\nrecombined in the drain superconductor. Unlike non-equilibrium scenarios for\nCooper pair splitting which involves superconducting/normal metal \"forks\", our\nproposal relies on an Aharonov-Bohm measurement of the DC Josephson current\nwhen a flux is inserted between the two dots. We provide a path integral\napproach to treat arbitrary transparencies, and we explore all contributions\nfor the individual phases ($0$ or $\\pi$) of the quantum dots. We propose a\ndefinition of the Cooper pair splitting efficiency for arbitrary\ntransparencies, which allows us to find the phase associations which favor the\ncrossed Andreev process. Possible applications to experiments using nanowires\nas quantum dots are discussed."
    },
    {
        "anchor": "Electron Transport in Granular Metals: We consider thermodynamic and transport properties of a long granular array\nwith strongly connected grains (inter-grain conductance g>>1.) We find that the\nsystem exhibits activated behavior of conductance and thermodynamic density of\nstates ~exp(-T*/T) where the gap, T*, is parametrically larger than the energy\nat which conventional perturbation theory breaks down. The scale T* represents\nenergy needed to create a long single-electron charge soliton propagating\nthrough the array.",
        "positive": "Magnetization-tuned topological quantum phase transition in MnBi2Te4\n  devices: Recently, the intrinsic magnetic topological insulator MnBi2Te4 has attracted\nenormous research interest due to the great success in realizing exotic\ntopological quantum states, such as the quantum anomalous Hall effect (QAHE),\naxion insulator state, high-Chern-number and high-temperature Chern insulator\nstates. One key issue in this field is to effectively manipulate these states\nand control topological phase transitions. Here, by systematic angle-dependent\ntransport measurements, we reveal a magnetization-tuned topological quantum\nphase transition from Chern insulator to magnetic insulator with gapped Dirac\nsurface states in MnBi2Te4 devices. Specifically, as the magnetic field is\ntilted away from the out-of-plane direction by around 40-60 degrees, the Hall\nresistance deviates from the quantization value and a colossal, anisotropic\nmagnetoresistance is detected. The theoretical analyses based on modified\nLandauer-Buttiker formalism show that the field-tilt-driven switching from\nferromagnetic state to canted antiferromagnetic state induces a topological\nquantum phase transition from Chern insulator to magnetic insulator with gapped\nDirac surface states in MnBi2Te4 devices. Our work provides an efficient means\nfor modulating topological quantum states and topological quantum phase\ntransitions."
    },
    {
        "anchor": "A tight binding model for quantum spin Hall effect on triangular optical\n  lattice: We propose a tight binding model for the quantum spin Hall system on\ntriangular optical lattice and we determined the edge state spectrum which\ncontains gap traversing states as the hallmark of $\\mathds{Z}_{2}$ topological\ninsulator. The advantage of this system is the possibility of implementing it\nin the fermionic ultracold atomic system whose nearly free electron limit is\nproposed by B. B\\'eri and N. R. Cooper, Phys. Rev. Lett. {\\bf 107}, 145301\n(2011).",
        "positive": "Impact of magnetic nanoparticles on the Casimir pressure in three-layer\n  systems: The Casimir pressure is investigated in three-layer systems where the\nintervening stratum possesses magnetic properties. This subject is gaining in\nimportance in connection with ferrofluids and their use in various\nmicroelectromechanical devices. We present general formalism of the Lifshitz\ntheory adapted to the case of ferrofluid sandwiched between two dielectric\nwalls. The Casimir pressure is computed for the cases of kerosene- and\nwater-based ferrofluids containing a 5% fraction of magnetite nanoparticles\nwith different diameters between silica glass walls. For this purpose, we have\nfound the dielectric permittivities of magnetite and kerosene along the\nimaginary frequency axis employing the available optical data and used the\nfamiliar dielectric properties of silica glass and water, as well as the\nmagnetic properties of magnetite. We have also computed the relative difference\nin the magnitudes of the Casimir pressure which arises on addition of magnetite\nnanoparticles to pure carrier liquids. It is shown that for nanoparticles of 20\nnm diameter at 2 micrometer separation between the walls this relative\ndifference exceeds 140% and 25% for kerosene- and water-based ferrofluids,\nrespectively. An interesting effect is found that at a fixed separation between\nthe walls an addition of magnetite nanoparticles with some definite diameter\nmakes no impact on the Casimir pressure. The physical explanation for this\neffect is provided. Possible applications of the obtained results are\ndiscussed."
    },
    {
        "anchor": "Electrical transport and persistent photoconductivity in monolayer MoS2\n  phototransistors: We study electrical transport properties in exfoliated molybdenum disulfide\n(MoS2) back-gated field effect transistors at low drain bias and under\ndifferent illumination intensities. It is found that photoconductive and\nphotogating effect as well as space charge limited conduction can\nsimultaneously occur. We point out that the photoconductivity increases\nlogarithmically with the light intensity and can persist with a decay time\nlonger than 10^4 s, due to photo-charge trapping at the MoS2/SiO2 interface and\nin MoS2 defects. The transfer characteristics present hysteresis that is\nenhanced by illumination. At low drain bias, the devices feature low contact\nresistance of 1.4 k{\\Omega}/{\\mu}m, ON current as high as 1.25 nA/{\\mu}m, 10^5\nON-OFF ratio, mobility of 1 cm^2/Vs and photoresponsivity R=1 A/W.",
        "positive": "Stability of topological properties of bismuth (111) bilayer: We investigate electronic and transport properties of bismuth (111) bilayer\nin the context of stability of its topological properties against different\nperturbations. The effects of spin-orbit coupling variations, geometry\nrelaxation and an interaction with a substrate are considered. Transport\nproperties are studied in the presence of Anderson disorder. Band structure\ncalculations are performed within multi-orbital tight-binding model and density\nfunctional theory methods. A band inversion process in bismuth (111) infinite\nbilayer and an evolution of edge states dispersion in ribbons as a function of\nspin-orbit coupling strength are analyzed. A significant change of orbital\ncomposition of the conduction and valence bands during a topological phase\ntransition is observed. A topological phase is shown to be robust when the\neffect of geometry relaxation is taken into account. An interaction with a\nsubstrate has similar effect to an external perpendicular electric field. The\nrobust quantized conductance is observed when the Fermi energy lies within the\nbulk energy gap, where only two counter-propagating edge states are present.\nFor energies where the Fermi level crosses more in-gap states, a scattering is\npossible between channels lying close in $k-$space. When the energy of edge\nstates overlaps with bulk states, no topological protection is observed."
    },
    {
        "anchor": "Nonadiabatic Dynamics of Molecules Interacting with Metal Surfaces: An\n  Approach Based on Langevin Dynamics and the Hierarchical Equations of Motion: A novel mixed quantum-classical approach to simulating nonadiabatic dynamics\nof molecules at metal surfaces is presented. The method combines the\nnumerically exact hierarchical equations of motion approach for the quantum\nelectronic degrees of freedom with Langevin dynamics for the classical degrees\nof freedom, namely low-frequency vibrational modes within the molecule. The\napproach extends previous mixed quantum-classical methods based on Langevin\nequations to models containing strong electron-electron or quantum\nelectronic-vibrational interactions, while maintaining a nonperturbative and\nnon-Markovian treatment of the molecule-metal coupling. To demonstrate the\napproach, nonequilibrium transport observables are calculated for a molecular\nnanojunction containing strong interactions.",
        "positive": "Geometric phase at graphene edge: We study the scattering phase shift of Dirac fermions at graphene edge. We\nfind that when a plane wave of a Dirac fermion is reflected at an edge of\ngraphene, its reflection phase is shifted by the geometric phase resulting from\nthe change of the pseudospin of the Dirac fermion in the reflection. The\ngeometric phase is the Pancharatnam-Berry phase that equals the half of the\nsolid angle on Bloch sphere determined by the propagation direction of the\nincident wave and also by the orientation angle of the graphene edge. The\ngeometric phase is finite at zigzag edge in general, while it always vanishes\nat armchair edge because of intervalley mixing. To demonstrate its physical\neffects, we first connect the geometric phase with the energy band structure of\ngraphene nanoribbon with zigzag edge. The magnitude of the band gap of the\nnanoribbon, that opens in the presence of the staggered sublattice potential\ninduced by edge magnetization, is related to the geometric phase. Second, we\nnumerically study the effect of the geometric phase on the Veselago lens formed\nin a graphene nanoribbon. The interference pattern of the lens is distinguished\nbetween armchair and zigzag nanoribbons, which is useful for detecting the\ngeometric phase."
    },
    {
        "anchor": "Comment on \"Electron screening and excitonic condensation in\n  double-layer graphene systems\": The influence of screening on the condensed state of bilayer graphene is\nstudied within the framework of the Thomas Fermi approximation. We find that\nscreening has little effect on the Kosterlitz-Thouless temperature in the\nstrongly interacting regime. Furthermore, we predict that the phase transition\nto the condensed state is first order.",
        "positive": "Imaging resonant dissipation from individual atomic defects in graphene: Conversion of electric current into heat involves microscopic processes that\noperate on nanometer length-scales and release minute amounts of power. While\ncentral to our understanding of the electrical properties of materials,\nindividual mediators of energy dissipation have so far eluded direct\nobservation. Using scanning nano-thermometry with sub-micro K sensitivity we\nvisualize and control phonon emission from individual atomic defects in\ngraphene. The inferred electron-phonon 'cooling power spectrum' exhibits sharp\npeaks when the Fermi level comes into resonance with electronic quasi-bound\nstates at such defects, a hitherto uncharted process. Rare in the bulk but\nabundant at graphene's edges, switchable atomic-scale phonon emitters define\nthe dominant dissipation mechanism. Our work offers new insights for addressing\nkey materials challenges in modern electronics and engineering dissipation at\nthe nanoscale."
    },
    {
        "anchor": "Spin-valley relaxation and quantum transport regimes in two-dimensional\n  transition metal dichalcogenides: Quantum transport and spintronics regimes are studied in p- and n-doped\natomic layers of hexagonal transition metal dichalcogenides (TMDCs), subject to\nthe interplay between the valley structure and spin-orbit coupling. We find how\nspin relaxation of carriers depends on their areal density and show that it\nvanishes for holes near the band edge, leading to the density-independent spin\ndiffusion length, and we develop a theory of weak\nlocalisation/antilocalisation, describing the crossovers between the\northogonal, double-unitary and symplectic regimes of quantum transport in\nTMDCs.",
        "positive": "Exploring quantum interference in heteroatom-substituted graphene-like\n  molecules: If design principles for controlling quantum interference in single molecules\ncould be elucidated and verified, then this will lay the foundations for\nexploiting such effects in nanoscale devices and thin-film materials.When the\ncore of a graphene-like polyaromatic hydrocarbon (PAH) is weakly coupled to\nexternal electrodes by atoms i and j, the single-molecule electrical\nconductance sigma-ij depends on the choice of connecting atoms i,j.\nFurthermore, conductance ratios sigma-ij/sigma-lm corresponding to different\nconnectivities i,j and l,m are determined by quantum interference within the\nPAH core. In this paper, we examine how such conductance ratios change when one\nof the carbon atoms within the \"parent\" PAH core is replaced by a heteroatom to\nyield a \"daughter\" molecule. For bipartite parental cores, in which\nodd-numbered sites are connected to even-numbered sites only, the effect of\nheteroatom substitution onto an odd-numbered site is summarized by the\nfollowing qualitative rules:\n  (a) When i and j are odd, both parent and daughter have low conductances (b)\nWhen i is odd and j is even, or vice versa both parent and daughter have high\nconductances (c) When i,j are both even, the parent has a low conductance and\nthe daughter a high conductance. These rules are verified by comparison with\ndensity-functional calculations on naphthalene, anthracene, pyrene and\nanthanthrene cores connected via two different anchor groups to gold\nelectrodes."
    },
    {
        "anchor": "Room temperature cavity electromechanics in the sideband-resolved regime: We demonstrate a sideband-resolved cavity electromechanical system operating\nat room temperature. The mechanical resonator, a strongly pre-stressed silicon\nnitride string, is dielectrically coupled to a three-dimensional microwave\ncavity made of copper. The electromechanical coupling is characterized by two\nmeasurements, the cavity-induced eigenfrequency shift of the mechanical\nresonator and the optomechanically induced transparency. While the former is\ndominated by dielectric effects, the latter reveals a clear signature of the\ndynamical backaction of the cavity field on the resonator. This unlocks the\nfield of cavity electromechanics for room temperature applications.",
        "positive": "Observation of the nonlinear Hall effect under time reversal symmetric\n  conditions: The electrical Hall effect is the production of a transverse voltage under an\nout-of-plane magnetic field. Historically, studies of the Hall effect have led\nto major breakthroughs including the discoveries of Berry curvature and the\ntopological Chern invariants. In magnets, the internal magnetization allows\nHall conductivity in the absence of external magnetic field. This anomalous\nHall effect (AHE) has become an important tool to study quantum magnets. In\nnonmagnetic materials without external magnetic fields, the electrical Hall\neffect is rarely explored because of the constraint by time-reversal symmetry.\nHowever, strictly speaking, only the Hall effect in the linear response regime,\ni.e., the Hall voltage linearly proportional to the external electric field,\nidentically vanishes due to time-reversal symmetry. The Hall effect in the\nnonlinear response regime, on the other hand, may not be subject to such\nsymmetry constraints. Here, we report the observation of the nonlinear Hall\neffect (NLHE) in the electrical transport of the nonmagnetic 2D quantum\nmaterial, bilayer WTe2. Specifically, flowing an electrical current in bilayer\nWTe2 leads to a nonlinear Hall voltage in the absence of magnetic field. The\nNLHE exhibits unusual properties sharply distinct from the AHE in metals: The\nNLHE shows a quadratic I-V characteristic; It strongly dominates the nonlinear\nlongitudinal response, leading to a Hall angle of about 90 degree. We further\nshow that the NLHE directly measures the \"dipole moment\" of the Berry\ncurvature, which arises from layer-polarized Dirac fermions in bilayer WTe2.\nOur results demonstrate a new Hall effect and provide a powerful methodology to\ndetect Berry curvature in a wide range of nonmagnetic quantum materials in an\nenergy-resolved way."
    },
    {
        "anchor": "Melting temperature of graphene: We present an approach to the melting of graphene based on nucleation theory\nfor a first order phase transition from the 2D solid to the 3D liquid via an\nintermediate quasi-2D liquid.\n  The applicability of nucleation theory, supported by the results of\nsystematic atomistic Monte Carlo simulations, provides an intrinsic definition\nof the melting temperature of graphene, $ T_m $, and allows us to determine it.\nWe find $T_m \\simeq 4510$ K, about 250 K higher than that of graphite using the\nsame interatomic interaction model. The found melting temperature is shown to\nbe in good agreement with the asymptotic results of melting simulations for\nfinite disks and ribbons of graphene. Our results strongly suggest that\ngraphene is the most refractory of all known materials.",
        "positive": "Normal metal tunnel junction-based superconducting quantum interference\n  proximity transistor: the N-SQUIPT: We report the fabrication and characterization of an alternative design for a\nsuperconducting quantum interference proximity transistor (SQUIPT) based on a\nnormal metal (N) probe. The absence of direct Josephson coupling between the\nproximized metal nanowire and the N probe allows us to observe the full\nmodulation of the wire density of states around zero voltage and current\n\\textit{via} the application of an external magnetic field. This results into a\ndrastic suppression of power dissipation which can be as low as a few $\\sim\n10^{-17}$ W. In this context the interferometer allows an improvement of up to\nfour orders of magnitude with respect to earlier SQUIPT designs, and makes it\nideal for extra-low power cryogenic applications. In addition, the N-SQUIPT has\nbeen recently predicted to be the enabling candidate for the implementation of\ncoherent caloritronic devices based on proximity effect."
    },
    {
        "anchor": "Prospects of carbyne applications in microelectronics: We design carbyne transistor which is integrable into the existing silicon\ntechnology and can be scaled up in a rather broad range -- starting from that\nprepared by us (by 0.5-mkm technology) up to the monomolecular one because the\nkey mechanism here is the inter-chain charge transfer.",
        "positive": "Many-body correlations brought to light in absorption spectra of diluted\n  magnetic semiconductors: Diluted magnetic semiconductors are materials well known to exhibit strong\ncorrelations which typically manifest in carrier-mediated magnetic ordering. In\nthis Rapid Communication, we show that the interaction between excitons and\nmagnetic impurities in these materials is even strong enough to cause a\nsignificant deviation from the bare exciton picture in linear absorption\nspectra of quantum well nanostructures. It is found that exciton-impurity\ncorrelations induce a characteristic fingerprint in the form of an additional\nfeature close to the exciton resonance in combination with a shift of the main\nexciton line of up to a few meV. We trace back these features to the form of\nthe self-energy and demonstrate that reliable values of the average correlation\nenergy per exciton can be extracted directly from the spectra. Since the only\nrequirement for our findings is sufficiently strong correlations, the results\ncan be generalized to other strongly correlated systems."
    },
    {
        "anchor": "Universal anyons at the irradiated surface of topological insulator: Anyons have recently received great attention due to their promising\napplication in topological quantum computation. The best validated system that\nenjoys the anyonic excitations are the Laughlin states. The quasi-particles in\nLaughlin states are neither fermions nor bosons but possess the discrete\nstatistical angle ? = ?=m, with m being an integer. Here we report a possible\nrealization of the universal Abelian anyons, whose statistical angle can be\ntuned continuously by external parameters and can take any arbitrary values\ninterpolating ? = 0 and ? = ?. The proposed setup is the surface state of a\nthree dimensional topological insulator driven by an amplitude-modulated\ncircularly-polarized light. It is found that the external field leads to a\nparticular Floquet phase, which is a two-spatial-dimensional analogy of the\nWeyl semimetal phase in the Floquet first Brillouin zone. The chiral anomaly of\nthis phase results in a U(1) Chern-Simons gauge theory with a tunable Floquet\nChern number. Owing to this underlying gauge field theory, the irradiated\nsurface of topological insulator constitutes a promising platform for the\nobservation of the universal anyons.",
        "positive": "Quantum metric and wavepackets at exceptional points in non-Hermitian\n  systems: The usual concepts of topological physics, such as the Berry curvature,\ncannot be applied directly to non-Hermitian systems. We show that another\nobject, the quantum metric, which often plays a secondary role in Hermitian\nsystems, becomes a crucial quantity near exceptional points in non-Hermitian\nsystems, where it diverges in a way that fully controls the description of\nwavepacket trajectories. The quantum metric behaviour is responsible for a\nconstant acceleration with a fixed direction, and for a non-vanishing constant\nvelocity with a controllable direction. Both contributions are independent of\nthe wavepacket size."
    },
    {
        "anchor": "A many-body overview of low-energy optical excitations in armchair\n  graphene nanoribbons: Excitonic spectra of armchair graphene nanoribbons (AGNRs) obtained from a\nfull many-body exact diagonalization of the Hubbard model are reported for both\nlongitudinally and transversely polarized photons, thus providing a complete\nsurvey of low-energy may-body optical excitations in these systems. The\nresulting one-photon allowed eigenstates turn out to be well separated in\nenergy from each other but both couple to the same set of two-photon allowed\nstates. The magnitude of the calculated optical oscillator strengths for\nperpendicular polarization suggest that these optical features can be indeed\nobserved in polarized absorption measurements.",
        "positive": "Current-induced CrI3 surface spin-flop transition probed by proximity\n  magnetoresistance in Pt: By exploiting proximity coupling, we probe the spin state of the surface\nlayers of CrI3, a van der Waals magnetic semiconductor, by measuring the\ninduced magnetoresistance (MR) of Pt in Pt/CrI3 nano-devices. We fabricate the\ndevices with clean and stable interfaces by placing freshly exfoliated CrI3\nflake atop pre-patterned thin Pt strip and encapsulating the Pt/CrI3\nheterostructure with hexagonal boron nitride (hBN) in a protected environment.\nIn devices consisting of a wide range of CrI3 thicknesses (30 to 150 nm), we\nobserve that an abrupt upward jump in Pt MR emerge at a 2 T magnetic field\napplied perpendicularly to the layers when the current density exceeds\n2.5x10^10 A/m2, followed by a gradual decrease over a range of 5 T. These\ndistinct MR features suggest a spin-flop transition which reveals strong\nantiferromagnetic interlayer coupling in the surface layers of CrI3. We study\nthe current dependence by holding the Pt/CrI3 sample at approximately the same\ntemperature to exclude the joule heating effect, and find that the MR jump\nincreases with the current density, indicating a spin current origin. This spin\ncurrent effect provides a new route to control spin configurations in\ninsulating antiferromagnets, which is potentially useful for spintronic\napplications."
    },
    {
        "anchor": "Topological phases: Classification of topological insulators and\n  superconductors of non-interacting Fermions, and beyond: After briefly recalling the quantum entanglement-based view of topological\nphases of matter in order to outline the general context, we give an overview\nof different approaches to the classification problem of topological insulators\nand superconductors of non-interacting Fermions. In particular, we review in\nsome detail general symmetry aspects of the \"ten-fold way\" which forms the\nfoundation of the classification, and put different approaches to the\nclassification in relationship with each other. We end by briefly mentioning\nsome of the results obtained on the effect of interactions, mainly in three\nspatial dimensions.",
        "positive": "Non-local Aharonov-Bohm conductance oscillations in an asymmetric\n  quan-tum ring: We investigate ballistic transport and quantum interference in a nanoscale\nquantum wire loop fab-ricated as a GaAs/AlGaAs field-effect heterostructure.\nFour-terminal measurements of current and voltage characteristics as a function\nof top gate voltages show negative bend resistance as a clear signature of\nballistic transport. In perpendicular magnetic fields phase-coherent transport\nleads to Aharonov-Bohm (AB) conductance oscillations which show equal\namplitudes in the local and the non-local measurement at a temperature of 1.5 K\nand above. We attribute this novel observation to the symmetry of the\northogonal cross junctions connecting the four quantum wire leads with the\nasymmetric quantum wire ring."
    },
    {
        "anchor": "The Two-impurity Anderson Model Revisited: Competition between Kondo\n  Effect and Reservoir-mediated Superexchange in Double Quantum Dots: We study a series-coupled double quantum dot in the Kondo regime modeled by\nthe two-impurity Anderson model and find a new conduction-band mediated\nsuperexchange interaction that competes with Kondo physics in the strong\nCoulomb interaction limit. Our numerical renormalization group results,\ncomplemented with the higher-order Rayleigh-Schr\\\"odinger perturbation theory,\nshow that the novel exchange mechanism leads to clear experimental consequences\nthat can be checked in transport measurements through double quantum dots.",
        "positive": "Gapped Dirac semimetal with mixed linear and parabolic dispersions: In this paper, we make a comprehensive study of the properties of a gapped\nDirac semimetal model, which was originally proposed in the magnetoinfrared\nspectroscopy measurement of ZeTe$_5$, and includes both the linear and\nparabolic dispersions in all three directions. We find that, depending on the\nband inversion parameters, $\\zeta'$ and $\\zeta_z'$, the model can support three\ndifferent phases: the single Dirac point (DP) phase, the double DPs phase and\nthe Dirac ring phase. The three different phases can be distinguished by their\nlow-energy features in the density of states (DOS) and optical conductivity. At\nhigh energy, both the DOS and optical conductivity exhibit power-law like\nbehaviors, with the asymptotic exponents depending heavily on the signs of\n$\\zeta'$ and $\\zeta_z'$. Moreover, the thumb-of-rule formula between the DOS\nand optical conductivity is satisfied only when $(\\zeta',\\zeta_z')>0$. The\nimplications of our results for experiments are discussed."
    },
    {
        "anchor": "Thermoelectric properties of electrically gated bismuth telluride\n  nanowires: We theoretically studied the effect of the perpendicular electric field on\nthe thermoelectric properties of the intrinsic, n-type and p-type bismuth\ntelluride nanowires with the growth direction [110]. The electronic structure\nand the wave functions were calculated by solving self-consistently the system\nof the Schrodinger and Poisson equations using the spectral method. The Poisson\nequation was solved in terms of the Newton - Raphson method within the\npredictor-corrector approach. The electron - electron exchange - correlation\ninteractions were taken into account in our analysis. In the temperature range\nfrom 77 to 500 K, the dependences of the Seebeck coefficient, thermal\nconductivity, electron (hole) concentration, and thermoelectric figure of merit\non the nanowire thickness, gate voltage, and excess hole (electron)\nconcentration were investigated in the constant relaxation-time approximation.\nThe results of our calculations indicate that the external perpendicular\nelectric field can increase the Seebeck coefficient of the bismuth telluride\nnanowires with thicknesses of 7 - 15 nm by nearly a factor of 2 and enhance ZT\nby an order of magnitude. At room temperature, ZT can reach a value as high as\n3.4 under the action of the external perpendicular electric field for realistic\nwidths of the nanowires. The obtain results may open up a completely new way\nfor a drastic enhancement of the thermoelectric figure of merit in a wide\ntemperature range.",
        "positive": "Intensity equations for birefringent spin lasers: Semiconductor spin lasers are distinguished from their conventional\ncounterparts by the presence of spin-polarized carriers. The transfer of\nangular momentum of the spin-polarized carriers to photons provides important\nopportunities for the operation of lasers. With the injection of spin-polarized\ncarriers, which lead to the circularly polarized light, the polarization of the\nemitted light can be changed an order of magnitude faster than its intensity.\nThis ultrafast operation of spin lasers relies on a large birefringence,\nusually viewed as detrimental in spin and conventional lasers. We introduce a\ntransparent description of spin lasers using intensity equations, which\nelucidate the influence of birefringence on the intensity and polarization\nmodulation of lasers. While intensity modulation is independent of\nbirefringence, for polarization modulation an increase in birefringence\ndirectly increases the resonant frequency. Our results for dynamical operation\nof lasers provide a guide for their spin-dependent response and spintronic\napplications beyond magnetoresistance."
    },
    {
        "anchor": "Non-Hermitian Floquet topological phases with arbitrarily many\n  real-quasienergy edge states: Topological states of matter in non-Hermitian systems have attracted a lot of\nattention due to their intriguing dynamical and transport properties. In this\nstudy, we propose a periodically driven non-Hermitian lattice model in\none-dimension, which features rich Floquet topological phases. The topological\nphase diagram of the model is derived analytically. Each of its non-Hermitian\nFloquet topological phases is characterized by a pair of integer winding\nnumbers, counting the number of real 0- and \\pi-quasienergy edge states at the\nboundaries of the lattice. Non-Hermiticity induced Floquet topological phases\nwith unlimited winding numbers are found, which allow arbitrarily many real 0-\nand \\pi-quasienergy edge states to appear in the complex quasienergy bulk gaps\nin a well-controlled manner. We further suggest to probe the topological\nwinding numbers of the system by dynamically imaging the stroboscopic spin\ntextures of its bulk states.",
        "positive": "Angle-dependent electron confinement in graphene moir\u00e9 superlattices: In graphene moir\\'e superlattices, electronic interactions between layers are\nmostly hidden as band structures get crowded because of folding, making their\ninterpretation cumbersome. Here, the evolution of the electronic band structure\nas a function of the interlayer rotation angle is studied using Density\nFunctional Theory followed by unfolding bands and then comparing them to their\ncorresponding individual components. We observe interactions at regions not\ntheoretically elucidated so far, where for small interlayer angles, gaps turn\ninto discrete-like states that are evenly spaced in energy. We find that\n$V_{pp\\sigma}$ attractive interactions between out-of-plane orbitals from\ndifferent layers are responsible for the discretization. Furthermore, when the\ninterlayer angle becomes small, these discrete evenly-spaced states have energy\ndifferences comparable to graphene phonons. Thus, they might be relevant to\nexplain electron-phonon-assisted effects, which have been experimentally\nobserved in graphene moir\\'e superlattices."
    },
    {
        "anchor": "Implications of the Klein tunneling times on high frequency graphene\n  devices using Bohmian trajectories: Because of its large Fermi velocity, leading to a great mobility, graphene is\nexpected to play an important role in (small signal) radio frequency\nelectronics. Among other, graphene devices based on Klein tunneling phenomena\nare already envisioned. The connection between the Klein tunneling times of\nelectrons and cut-off frequencies of graphene devices is not obvious. We argue\nin this paper that the trajectory-based Bohmian approach gives a very natural\nframework to quantify Klein tunneling times in linear band graphene devices\nbecause of its ability to distinguish, not only between transmitted and\nreflected electrons, but also between reflected electrons that spend time in\nthe barrier and those that do not. Without such distinction, typical\nexpressions found in the literature to compute dwell times can give unphysical\nresults when applied to predict cut-off frequencies. In particular, we study\nKlein tunneling times for electrons in a two-terminal graphene device\nconstituted by a potential barrier between two metallic contacts. We show that\nfor a zero incident angle (and positive or negative kinetic energy), the\ntransmission coefficient is equal to one, and the dwell time is roughly equal\nto the barrier distance divided by the Fermi velocity. For electrons incident\nwith a non-zero angle smaller than the critical angle, the transmission\ncoefficient decreases and dwell time can still be easily predicted in the\nBohmian framework. The main conclusion of this work is that, contrary to\ntunneling devices with parabolic bands, the high graphene mobility is roughly\nindependent of the presence of Klein tunneling phenomena in the active device\nregion.",
        "positive": "Minority-carrier dynamics in semiconductors probed by two-photon\n  microscopy: Two-photon time-resolved photoluminescence has been recently applied to\nvarious semiconductor devices to determine carrier lifetime and surface\nrecombination velocities. So far the theoretical modeling activity has been\nmainly limited to the commonly used one-photon counterpart of the technique.\nHere we provide the analytical solution to a 3D diffusion equation that\ndescribes two-photon microscopy in the low-injection regime. We focus on a\nsystem with a single buried interface with enhanced recombination, and analyze\nhow transport, bulk and surface recombinations influence photoluminescence\ndecays. We find that bulk measurements are dominated by diffusion at short\ntimes and by bulk recombination at long times. Surface recombination modifies\nbulk signals when the optical spot is less than a diffusion length away from\nthe probed interface. In addition, the resolution is increased as the spot size\nis reduced, which however makes the signal more sensitive to diffusion."
    },
    {
        "anchor": "What is a proper definition of spin current? -- Lessons from the\n  Kane-Mele Model: Spin current, a key concept in spintronics that carries spin angular\nmomentum, has a non-unique definition due to the non-conservation of spins in\nsolids. While two primary definitions exist -- conventional spin current and\nconserved spin current -- their validity has not been quantitatively examined.\nHere, we examine the validity of these definitions of spin current by comparing\ntheir spin Hall conductivities to the spin accumulation on edges of materials\ncalculated in a real-time evolution simulation. Employing the Kane-Mele model\nwith the Rashba term, which explicitly violates spin conservation, we reveal\nthat the spin Hall conductivities calculated under both definitions fail to\nreproduce the simulated results of spin accumulation when the Rashba term is\nlarge. Our results suggest that the standard definitions of spin current and\nthe associated spin Hall conductivity do not give an accurate quantitative\nestimate of spin accumulation. This conclusion indicates that real-time\nsimulations are necessary to accurately estimate spin accumulation on\nedges/surfaces of materials.",
        "positive": "Light-dependent Impedance Spectra and Transient Photoconductivity in a\n  Ruddlesden-Popper 2D Lead-halide Perovskite Revealed by Electrical Scanned\n  Probe Microscopy and Accompanying Theory: Electric force microscopy was used to record the light-dependent impedance\nspectrum and the probe transient photoconductivity of a film of butylammonium\nlead iodide, BA$_{2}$PbI$_{4}$, a 2D Ruddlesden--Popper perovskite\nsemiconductor. The impedance spectrum of BA$_{2}$PbI$_{4}$ showed modest\nchanges as the illumination intensity was varied up to 1400 mW/cm$^{2}$, in\ncontrast with the comparatively dramatic changes seen for 3D lead-halide\nperovskites under similar conditions. BA$_{2}$PbI$_{4}$'s light-induced\nconductivity had a rise time and decay time of $\\sim$ 100 $\\mu$s, 10$^{4}$\nslower than expected from direct electron-hole recombination and yet 10$^{5}$\nfaster than the conductivity-recovery times recently observed in 3D lead-halide\nperovskites and attributed to the relaxation of photogenerated vacancies. What\nsample properties are probed by electric force microscope measurements remains\nan open question. A Lagrangian-mechanics treatment of the electric force\nmicroscope experiment was recently introduced by Dwyer, Harrell, and Marohn\nwhich enabled the calculation of steady-state electric force microscope signals\nin terms of a complex sample impedance. Here this impedance treatment of the\ntip-sample interaction is extended, through the introduction of a\ntime-dependent transfer function, to include time-resolved electrical scanned\nprobe measurements. It is shown that the signal in a phase-kick electric force\nmicroscope experiment, and therefore also the signal in a time-resolved\nelectrostatic force microscope experiment, can be written explicitly in terms\nof the sample's time-dependent resistance (i.e., conductivity)."
    },
    {
        "anchor": "Isotope effect in acetylene C$_2$H$_2$ and C$_2$D$_2$ rotations on\n  Cu(001): A comprehensive analysis of the elementary processes behind the scanning\ntunneling microscope controlled rotation of C$_2$H$_2$ and C$_2$D$_2$,\nisotopologues of a single acetylene molecule adsorbed on the Cu(001) surface is\ngiven, with a focus on the isotope effects. With the help of density-functional\ntheory we calculate the vibrational modes of C$_2$H$_2$ and C$_2$D$_2$ on\nCu(001) and estimate the anharmonic couplings between them, using a simple\nstrings-on-rods model. The probability of the elementary processes --\nnon-linear and combination band -- are estimated using the Keldysh diagram\ntechnique. This allows us to clarify the main peculiarities and the isotope\neffects of the C$_2$H$_2$ and C$_2$D$_2$ on Cu(001) rotation, discovered in the\npioneering work [Stipe et al., Phys. Rev. Lett. 81, 1263 (1998)], which have\nnot been previously understood.",
        "positive": "Interference of chiral Andreev edge states: The search for topological excitations such as Majorana fermions has spurred\ninterest in the boundaries between distinct quantum states. Here, we explore an\ninterface between two prototypical phases of electrons with conceptually\ndifferent ground states: the integer quantum Hall insulator and the s-wave\nsuperconductor. We find clear signatures of hybridized electron and hole states\nsimilar to chiral Majorana fermions, to which we refer as chiral Andreev edge\nstates (CAES). They propagate along the interface in the direction determined\nby magnetic field and their interference can turn an incoming electron into an\noutgoing electron or a hole, depending on the phase accumulated by the CAES\nalong their path. Our results demonstrate that these excitations can propagate\nand interfere over a significant length, opening future possibilities for their\ncoherent manipulation."
    },
    {
        "anchor": "Topological Zero-Energy Modes in Gapless Commensurate\n  Aubry-Andr\u00e9-Harper Models: The Aubry-Andr\\'e or Harper (AAH) model has been the subject of extensive\ntheoretical research in the context of quantum localization. Recently, it was\nshown that one-dimensional quasicrystals described by the incommensurate AAH\nmodel has a nontrivial topology. In this Letter, we show that the commensurate\noff-diagonal AAH model is topologically nontrivial in the gapless regime and\nsupports zero-energy edge modes. Unlike the incommensurate case, the nontrivial\ntopology in the off-diagonal AAH model is attributed to the topological\nproperties of the one-dimensional Majorana chain. We discuss the feasibility of\nexperimental observability of our predicted topological phase in the\ncommensurate AAH model.",
        "positive": "Fractional second-order topological insulator from a three-dimensional\n  coupled-wires construction: We construct a three-dimensional second-order topological insulator with\ngapless helical hinge states from an array of weakly tunnel-coupled Rashba\nnanowires. For suitably chosen interwire tunnelings, we demonstrate that the\nsystem has a fully gapped bulk as well as fully gapped surfaces, but hosts a\nKramers pair of gapless helical hinge states propagating along a path of hinges\nthat is determined by the hierarchy of interwire tunnelings and the boundary\ntermination of the system. Furthermore, the coupled-wires approach allows us to\nincorporate electron-electron interactions into our description. At suitable\nfilling factors of the individual wires, we show that sufficiently strong\nelectron-electron interactions can drive the system into a fractional\nsecond-order topological insulator phase with hinge states carrying only a\nfraction $e/p$ of the electronic charge $e$ for an odd integer $p$."
    },
    {
        "anchor": "Controlling nanothread backbone structure through precursor design: Nanothreads are 1D carbon-based nanomaterials produced by pressure-induced\npolymerization of multiply unsaturated (and typically aromatic) precursors with\nmultiple bonds between adjacent precursors. We computationally design\nnon-covalent interactions between functional groups on thread-forming monomers\nto control the relative stabilities of different nanothread backbones. In\nparticular, functionalized furan or thiophene precursors are identified that\nfavor nanothreads with oxygen or sulfur atoms arrayed along the same side of\nthe thread backbone, rather than on alternating sides as currently seen\nexperimentally for threads formed from unfunctionalized furan or thiophene.\nThis heteroatom chain provides opportunities for unusual properties arising\nfrom a sterically compressed one-dimensional chain of p orbitals.",
        "positive": "Fractional quantum conductance staircase of edge hole channels in\n  silicon quantum wells: We present the findings for the fractional quantum conductance of holes that\nis caused by the edge channels in the silicon nanosandwich prepared within\nframeworks of the Hall geometry. This nanosandwich represents the ultra-narrow\np-type silicon quantum well (Si-QW), 2 nm, confined by the {\\delta}-barriers\nheavily doped with boron on the n-type Si (100) surface. The edge channels in\nthe Si-QW plane are revealed by measuring the longitudinal quantum conductance\nstaircase, Gxx, as a function of the voltage applied to the Hall contacts, Vxy,\nto a maximum of 4e2/h. In addition to the standard plateau, 2e2/h, the\nvariations of the Vxy voltage appear to exhibit the fractional form of the\nquantum conductance staircase with the plateaus and steps that bring into\ncorrelation respectively with the odd and even fractional values."
    },
    {
        "anchor": "Non-adiabatic corrections to chiral charge pumping in topological nodal\n  semimetals: Studying many-body versions of Landau-Zener-like problems of non-interacting\nelectrons in the Slater formalism for several $k \\cdot p$ models representing\nWeyl and Dirac semimetals, we systematically include non-adiabatic corrections\nto a quantum limit of chiral charge pumping in these models. In this paper, we\nshow that relative homotopy invariant [Sun et al., Phys. Rev. Lett. 121, 106402\n(2018)] and Euler class invariant [Bouhon et al., Nat. Phys. 16, 1137 (2020)]\nnon-trivially manifest in the non-adiabatic corrections to the quantum limit of\nchiral charge pumping. These corrections could affect conductivity channels\nconnected with the presence of chiral anomaly. Moreover, we show that, for\nnon-symmorphic systems, this contribution is sensitive to the direction of the\napplied magnetic field (in respect to the so-called non-symmorphic nodal loop),\nsuggesting that the conjectured direction-selective chiral anomaly in\nnon-symmorphic systems [Bzdu\\v{s}ek et al., Nature (London) 538, 75 (2016)]\ncould lead to a strongly anisotropic longitudinal magnetoresistance. The\npresented approach can be easily applied to other $k \\cdot p$ or tight-binding\nmodels.",
        "positive": "Inhomogeneous superconductivity and quasilinear magnetoresistance at\n  amorphous LaTiO3/SrTiO3 interfaces: We have studied the transport properties of LaTiO3/SrTiO3 (LTO/STO)\nheterostructures. In spite of 2D growth observed in reflection high energy\nelectron diffraction, Transmission Electron Microscopy images revealed that the\nsamples tend to amorphize. Still, we observe that the structures are\nconducting, and some of them exhibit high conductance and/or superconductivity.\nWe established that conductivity arises mainly on the STO side of the\ninterface, and shows all the signs of the 2-dimensional electron gas usually\nobserved at interfaces between SrTiO3 and LaTiO3 or LaAlO3, including the\npresence of two electron bands and tunability with a gate voltage. Analysis of\nmagnetoresistance (MR) and superconductivity indicates presence of a spatial\nfluctuations of the electronic properties in our samples. That can explain the\nobserved quasilinear out-of-plane MR, as well as various features of the\nin-plane MR and the observed superconductivity."
    },
    {
        "anchor": "Dissipation and spontaneous emission in quantum electrodynamical density\n  functional theory based on optimized effective potential: A proof of concept\n  study: We generalize the optimized effective potential (OEP) formalism in the\nquantum electrodynamical density functional theory (QEDFT) to the case of\ncontinuous distribution of photon modes, and study its applicability to\ndissipative dynamics of electron systems interacting with photons of lossy\ncavities. Specifically, we test whether this technique is capable of capturing\nthe quantum features of electron-photon interaction related to spontaneous\nemission and the corresponding energy transfer from the electrons to cavity\nphotons. For this purpose, we analyze a discrete three-site system with one\nelectron coupled to photons of the cavity, which, in fact, is a minimal model\nallowing to eliminate classical radiation and the corresponding energy loss,\nbut still have nontrivial density dynamics. By considering two typical spectral\ndensities of photon modes, modeling (i) lossy cavity with Lorentzian broadening\nof photon peaks, and (ii) the Ohmic bath, and several representative dynamical\nregimes, we find that OEP-QEDFT demonstrates a good qualitative and\nquantitative performance, especially in the case when the disspation is\ndominated by one-photon processes.",
        "positive": "Spin-boson quantum phase transition in multilevel superconducting qubits: Superconducting circuits are currently developed as a versatile platform for\nthe exploration of many-body physics, by building on non-linear elements that\nare often idealized as two-level qubits. A classic example is given by a charge\nqubit that is capacitively coupled to a transmission line, which leads to the\ncelebrated spin-boson description of quantum dissipation. We show that the\nintrinsic multilevel structure of superconducting qubits drastically restricts\nthe validity of the spin-boson paradigm due to phase localization, which\nspreads the wavefunction over many charge states. Numerical Renormalization\nGroup simulations also show that the quantum critical point moves out of the\nphysically accessible range in the multilevel regime. Imposing charge\ndiscreteness in a simple variational state accounts for these multilevel\neffects, that are relevant for a large class of devices."
    },
    {
        "anchor": "Optimal geometry of lateral GaAs and Si/SiGe quantum dots for electrical\n  control of spin qubits: We investigate the effects of the orientation of the magnetic field and the\norientation of a quantum dot, with respect to crystallographic coordinates, on\nthe quality of an electrically controlled qubit realized in a gated\nsemiconductor quantum dot. We find that, due to the anisotropy of the\nspin-orbit interactions, varying the two orientations it is possible to tune\nthe qubit in the sense of optimizing the ratio of its couplings to phonons and\nto a control electric field. We find conditions under which such optimal setup\ncan be reached by solely reorienting the magnetic field, and when a specific\npositioning of the dot is required. We also find that the knowledge of the\nrelative sign of the spin-orbit interactions strengths allows to choose a\nrobust optimal dot geometry, with the dot main axis along [110], or\n[1$\\overline{1}$0], where the qubit can be always optimized by reorienting the\nmagnetic field.",
        "positive": "Photoluminescence quenching in gold - MoS2 hybrid nanoflakes: Achieving tunability of two dimensional (2D) transition metal dichalcogenides\n(TMDs) functions calls for the introduction of hybrid 2D materials by means of\nlocalized interactions with zero dimensional (0D) materials. A\nmetal-semiconductor interface, as in gold (Au) - molybdenum disulfide (MoS2),\nis of great interest from the standpoint of fundamental science as it\nconstitutes an outstanding platform to investigate plasmonic-exciton\ninteractions and charge transfer. The applied aspects of such systems introduce\nnew options for electronics, photovoltaics, detectors, gas sensing, catalysis,\nand biosensing. Here we consider pristine MoS2 and study its interaction with\nAu nanoislands, resulting in local variations of photoluminescence (PL)\nassociated with various Au-MoS2 hybrid configurations. By controllably\ndepositing monolayers of Au on MoS2 to form Au nanostructures of given size and\nthickness, we investigate the electronic structure of the resulting hybrid\nsystems. We present strong evidence of PL quenching of MoS2 as a result of\ncharge transfer from MoS2 to Au: p-doping of MoS2. The results suggest new\navenues for 2D nanoelectronics, active control of transport or catalytic\nproperties."
    },
    {
        "anchor": "Voltage-controlled transmission in a dielectric slab doped with the\n  quantum dot molecules: Transmission and reflection of an electromagnetic pulse through a dielectric\nslab doped with the quantum dot molecules is investigated. It is shown that the\ntransmitted and reflected pulses depend on the inter-dot tunneling effect and\ncan be controlled by applying a gate voltage.",
        "positive": "Non-Hermitian Boundary State Engineering in Anomalous Floquet\n  Topological Insulators: In Hermitian topological systems, the bulk-boundary correspondence strictly\nconstraints boundary transport to values determined by the topological\nproperties of the bulk. We demonstrate that this constraint can be lifted in\nnon-Hermitian Floquet insulators. Provided that the insulator supports an\nanomalous topological phase, non-Hermiticity allows us to modify the boundary\nstates independently of the bulk, without sacrificing their topological nature.\nWe explore the ensuing possibilities for a Floquet topological insulator with\nnon-Hermitian time-reversal symmetry, where the helical transport via\ncounterpropagating boundary states can be tailored in ways that overcome the\nconstraints imposed by Hermiticity. Non-Hermitian boundary state engineering\nspecifically enables the enhancement of boundary transport relative to bulk\nmotion, helical transport with a preferred direction, and chiral transport in\nthe same direction on opposite boundaries. We explain the experimental\nrelevance of our findings for the example of photonic waveguide lattices."
    },
    {
        "anchor": "From Transparent Conduction to Coulomb Blockade at Fixed Hole Number: We present a complex set of transport spectroscopy data on a clean\nsingle-wall carbon nanotube device in high magnetic fields. At zero axial\nfield, the device displays in hole conduction with increasingly negative gate\nvoltage a fast transition towards high contact transparency and eventually\nFabry-Perot interference of conductance. When increasing the axial field\ncomponent up to B=17T, the contact transparency and the overall conductance are\nreduced all the way to Coulomb blockade, clearly displaying the subsequent\ncharging with the first 10 holes. The continuous transition between the\ntransport regimes is dominated by a rich spectrum of Kondo-like resonances,\nwith distinct features in the stability diagrams.",
        "positive": "Interaction induced AC-Stark shift of exciton-polaron resonances: Laser induced shift of atomic states due to the AC-Stark effect has played a\ncentral role in cold-atom physics and facilitated their emergence as analog\nquantum simulators. Here, we explore this phenomena in an atomically thin layer\nof semiconductor MoSe$_2$, which we embedded in a heterostructure enabling\ncharge tunability. Shining an intense pump laser with a small detuning from the\nmaterial resonances, we generate a large population of virtual collective\nexcitations, and achieve a regime where interactions with this background\npopulation is the leading contribution to the AC-Stark shift. Using this\ntechnique we study how itinerant charges modify -- and dramatically enhance --\nthe interactions between optical excitations. In particular, our experiments\nshow that the interaction between attractive polarons could be more than an\norder of magnitude stronger than those between bare excitons."
    },
    {
        "anchor": "Controlling the nucleation and annihilation of skyrmions with\n  magnetostatic interactions: Skyrmions have become one of the most visited topics during the last decade\nin condensed matter physics. In this work, and by means of analytical\ncalculations and micromagnetic simulations, we explore the effect of the\nmagnetostatic field generated by a magnetic tip on the stability of skyrmions.\nOur results show that the interaction energy between the tip and the skyrmion\nplays a fundamental role in the stabilization of N\\'eel skyrmions confined in\nnanodisks, allowing its nucleation and annihilation, and also providing precise\ncontrol of its size and polarity. Based on our results, we propose a very\nsimple and cyclic method to nucleate and annihilate skyrmions, as well as to\ncontrol their polarity and chirality. This proposal could open new\npossibilities for logic devices taking advantage of all the degrees of freedom\nthat skyrmionic textures have.",
        "positive": "Berry's Phase for Standing Wave Near Graphene Edge: Standing waves near the zigzag and armchair edges, and their Berry's phases\nare investigated. It is suggested that the Berry's phase for the standing wave\nnear the zigzag edge is trivial, while that near the armchair edge is\nnon-trivial. A non-trivial Berry's phase implies the presence of a singularity\nin parameter space. We have confirmed that the Dirac singularity is absent\n(present) in the parameter space for the standing wave near the zigzag\n(armchair) edge. The absence of the Dirac singularity has a direct consequence\nin the local density of states near the zigzag edge. The transport properties\nof graphene nanoribbons observed by recent numerical simulations and\nexperiments are discussed from the point of view of the Berry's phases for the\nstanding waves."
    },
    {
        "anchor": "Exchange mechanism for electron paramagnetic resonance of individual\n  adatoms: We propose a new universal mechanism that makes it possible to drive an\nindividual atomic spin using a spin polarized scanning tunnel microscope (STM)\nwith an oscillating electric signal. We show that the combination of the\ndistance dependent exchange with the magnetic tip and the electrically driven\nmechanical oscillation of the surface spins permits to control their quantum\nstate. Based on a combination of density functional theory and multiplet\ncalculations, we show that the proposed mechanism is essential to account for\nthe recently observed electrically driven paramagnetic spin resonance (ESR) of\nan individual Fe atom on a MgO/Ag(100) surface. Our findings set the foundation\nto deploy the ESR-STM quantum sensing technique to a much broader class of\nsystems.",
        "positive": "Current-Driven Dynamics of Skyrmions Stabilized in MnSi Nanowires\n  Revealed by Topological Hall Effect: Skyrmions, novel topologically stable spin vortices, hold promise for\nnext-generation magnetic storage due to their nanoscale domains to enable high\ninformation storage density and their low threshold for current-driven motion\nto enable ultralow energy consumption. One-dimensional (1D) nanowires are ideal\nhosts for skyrmions since they not only serve as a natural platform for\nmagnetic racetrack memory devices but also can potentially stabilize skyrmions.\nHere we use the topological Hall effect (THE) to study the phase stability and\ncurrent-driven dynamics of the skyrmions in MnSi nanowires. The THE was\nobserved in an extended magnetic field-temperature window (15 to 30 K),\nsuggesting stabilization of skyrmion phase in nanowires compared with the bulk\n(27 to 29.5 K). Furthermore, for the first time, we study skyrmion dynamics in\nthis extended skyrmion phase region and found that under the high\ncurrent-density of $10^{8}-10^{9} Am^{-2}$ enabled by nanowire geometry, the\nTHE decreases with increasing current densities, which demonstrates the\ncurrent-driven motion of skyrmions generating the emergent electric field.\nThese results open up the exploration of nanowires as an attractive platform\nfor investigating skyrmion physics in 1D systems and exploiting skyrmions in\nmagnetic storage concepts."
    },
    {
        "anchor": "Acoustic plasmons in type-I Weyl semimetals: Massless chiral fermions emergent in inversion symmetry-breaking Weyl\nsemimetals (WSMs) reside in the vicinity of multiple low symmetry nodes and\nthus acquire strongly anisotropic dispersion. We investigate the longitudinal\nelectromagnetic modes of two-component degenerate Weyl plasma relevant to the\nrealistic band structure of type-I WSM. We show that the actual spectrum of\nthree dimensional collective density excitations in TaAs family of WSM is\ngaples due to emergence of acoustic plasmons corresponding to out-of-phase\noscillations of the plasma components. These modes exist around the [001]\ncrystallographic direction and are weakly damped, thanks to large difference in\nthe Weyl velocities of the $W_1$ and $W_2$ quasiparticles when propagating\nalong [001]. We show that acoustic plasmons can manifest themselves as slow\nbeatings of electric potential superimposed on fast plasmonic oscillations upon\ncharge relaxation. The revealed acoustic modes can stimulate purely electronic\nsuperconductivity, collisionless plasmon instabilities, and formation of Weyl\nsoundarons.",
        "positive": "Strain-induced Fermi contour anisotropy of GaAs 2D holes: We report measurements of magneto-resistance commensurability peaks, induced\nby a square array of anti-dots, in GaAs (311)A two-dimensional holes as a\nfunction of applied in-plane strain. The data directly probe the shapes of the\nFermi contours of the two spin subbands that are split thanks to the spin-orbit\ninteraction and strain. The experimental results are in quantitative agreement\nwith the predictions of accurate energy band calculations, and reveal that the\nmajority spin-subband has a severely distorted Fermi contour whose anisotropy\ncan be tuned with strain."
    },
    {
        "anchor": "Environmental Instability and Degradation of Single- and Few-Layer WTe2\n  Nanosheets in Ambient Conditions: Since the discovery of large, non-saturating magnetoresistance in bulk WTe2\nwhich allows microexfoliation, single- and few-layer WTe2 crystals have\nattracted increasing interests. However, as it mentioned in existing studies,\nWTe2 flakes appear to degrade in ambient conditions. Here we report\nexperimental observations of saturating degradation in few-layer WTe2 through\nRaman spectroscopy characterization and careful monitoring of the degradation\nof single-, bi- and tri-layer (1L, 2L & 3L) WTe2 over long time. Raman peak\nintensity decreases during WTe2 degradation and 1L flakes degrade faster than\n2L and 3L flakes. The relatively faster degradation in 1L WTe2 could be\nattributed to low energy barrier of oxygen reaction with WTe2. We further\ninvestigate the degradation mechanisms of WTe2 using XPS and AES and find that\noxidation of Te and W atoms is the main reason of WTe2 degradation. In\naddition, we observe oxidation occurs only in the depth of 0.5nm near the\nsurface, and the oxidized WTe2 surface could help prevent inner layers from\nfurther degradation.",
        "positive": "Single Dirac point and helical states in a one-dimensional system: Odd numbers of Dirac points and helical states can exist at edges (surfaces)\nof two-dimensional (three-dimensional) topological insulators. In the bulk of a\none-dimensional lattice (not an edge) with time reversal symmetry, however, a\nno-go theorem forbids the existence of an odd number of Dirac points or helical\nstates. Introducing a magnetic field can violate the time reversal condition\nbut would usually lift the degeneracy at the Dirac points. We find that a\nspatially periodic magnetic field with zero mean value can induce a single\nDirac point in a one-dimensional system with spin-orbit coupling. A wealth of\nnew physics may emerge due to the existence of a single Dirac point and helical\nstates in the bulk of a one-dimensional lattice (rather than edge states). A\nseries of quantized numbers emerge due to the non-trivial topology of the 1D\nhelical states, including the doubled period of helical Bloch oscillations,\nquantized conductance near the Dirac point, and 1/2-charge solitons at mass\nkinks. Such a system can be realized in one-dimensional semiconductor systems\nor in optical traps of atoms."
    },
    {
        "anchor": "Thermoelectric and Seebeck coefficients of granular metals: In this work we present a detailed study and derivation of the thermopower\nand thermoelectric coefficient of nano-granular metals at large tunneling\nconductance between the grains, g_T>> 1. An important criterion for the\nperformance of a thermoelectric device is the thermodynamic figure of merit\nwhich is derived using the kinetic coefficients of granular metals. All results\nare valid at intermediate temperatures, E_c>>T/g_T>\\delta, where \\delta is the\nmean energy level spacing for a single grain and E_c its charging energy. We\nshow that the electron-electron interaction leads to an increase of the\nthermopower with decreasing grain size and discuss our results in the light of\nfuture generation thermoelectric materials for low temperature applications.\nThe behavior of the figure of merit depending on system parameters like grain\nsize, tunneling conductance, and temperature is presented.",
        "positive": "Oscillating magnetoresistance in graphene p-n junctions at intermediate\n  magnetic fields: We report on the observation of magnetoresistance oscillations in graphene\np-n junctions. The oscillations have been observed for six samples, consisting\nof single-layer and bilayer graphene, and persist up to temperatures of 30 K,\nwhere standard Shubnikov-de Haas oscillations are no longer discernible. The\noscillatory magnetoresistance can be reproduced by tight-binding simulations.\nWe attribute this phenomenon to the modulated densities of states in the n- and\np- regions."
    },
    {
        "anchor": "Collapse of the vacuum in hexagonal graphene quantum dots: a comparative\n  study between the tight-binding and the mean-field Hubbard models: In this paper, we perform a systematic study on the electronic, magnetic, and\ntransport properties of the hexagonal graphene quantum dots (GQDs) with\narmchair edges in the presence of a charged impurity using two different\nconfigurations: (1) a central Coulomb potential and (2) a positively charged\ncarbon vacancy. The tight binding (TB) and the half-filled extended Hubbard\nmodels are numerically solved and compared with each other in order to reveal\nthe effect of electron interactions and system sizes. Numerical results point\nout that off-site Coulomb repulsion leads to an increase in the critical\ncoupling constant to $\\beta_{\\text{c}}$ = 0.6 for a central Coulomb potential.\nThis critical value of the $\\beta$ is found to be independent of GQD size,\nreflecting its universality even in the presence of electron-electron\ninteractions. In addition, a sudden downshift in the transmission peaks shows a\nclear signature of the transition from subcritical $\\beta$ $<$\n$\\beta_{\\text{c}}$ to supercritical $\\beta$ $>$ $\\beta_{\\text{c}}$ regime. On\nthe other hand, for a positively charged vacancy, the collapse of the lowest\nbound state occurs at $\\beta_{\\text{c}}$ = 0.7 for the interacting case.\nInterestingly, the local magnetic moment, induced by a bare carbon vacancy, is\ntotally quenched when the vacancy is subcritically charged, whereas the valley\nsplittings in electron and hole channels continue to exist in both regimes.",
        "positive": "Symmetries of the Resistance of Mesoscopic Samples in the Quantum Hall\n  Regime: The symmetry properties of the resistance of mesoscopic samples in the\nquantum Hall regime are investigated. In addition to the reciprocity relation,\nour samples obey new symmetries, that relate resistances measured with\ndifferent contact configurations. Different kinds of symmetries are identified,\ndepending on whether the magnetic field value is such that the system is above,\nor below, a quantum Hall transition. Related symmetries have recently been\nreported for macroscopic samples in the quantum Hall regime by Ponomarenko {\\it\net al.} (Solid State Commun. {\\bf 130}, 705 (2004)), and Karmakar {\\it et al.}\n(Preprint cond-mat/0309694)."
    },
    {
        "anchor": "Opportunities in topological insulator devices: Topological insulators (TIs) are expected to be a promising platform for\nnovel quantum phenomena, whose experimental realizations require sophisticated\ndevices. In this Technical Review, we discuss four topics of particular\ninterest for TI devices: topological superconductivity, quantum anomalous Hall\ninsulator as a platform for exotic phenomena, spintronic functionalities, and\ntopological mesoscopic physics. We also discuss the present status and\ntechnical challenges in TI device fabrications to address new physics.",
        "positive": "Reduced frequency noise in superconducting resonators: We report a reduction of the frequency noise in coplanar waveguide\nsuperconducting resonators. The reduction of 7 dB is achieved by removing the\nexposed dielectric substrate surface from the region with high electric fields\nand by using NbTiN. In a model-analysis the surface of NbTiN is found to be a\nnegligible source of noise, experimentally supported by a comparison with NbTiN\non SiOx resonators. The reduction is additive to decreasing the noise by\nwidening the resonators."
    },
    {
        "anchor": "Niobium Dayem nano-bridge Josephson field-effect transistors: We report on the first realization of Nb-based \\textit{all-metallic} gated\nDayem nano-bridge field-effect transistors (Nb-FETs). These Josephson devices\noperate up to a temperature of $\\sim 3$ K, and exhibit full suppression of the\nsupercurrent thanks to the application of a control gate voltage. The\ndependence of the kinetic inductance and of the transconductance on gate\nvoltage promises a performance already on par with so far realized metallic\nJosephson transistors, and let to foresee the implementation of a\nsuperconducting digital logic based on Nb-FETs. We conclude by showing the\npractical realization of a scheme implementing an all-metallic gate-tunable\n\\emph{half-wave} rectifier to be used either for superconducting electronics or\nfor photon detection applications.",
        "positive": "Resonant dephasing in the electronic Mach-Zehnder interferometer: We address the recently-observed unexpected behavior of Aharonov-Bohm\noscillations in the electronic Mach-Zehnder interferometer that was realized\nexperimentally in a quantum Hall system [1]. We argue that the measured lobe\nstructure in the visibility of oscillations and the phase rigidity result from\na strong long-range interaction between two adjacent counter-propagating edge\nstates, which leads to a resonant scattering of plasmons. The visibility and\nphase shift, which we expressed in terms of the transmission coefficient for\nplasmons, can be used for the tomography of edge states."
    },
    {
        "anchor": "Torsion, energy magnetization and thermal Hall effect: We study the effective action of hydrostatic response to torsion in the\nabsence of spin connections in gapped $\\left(2+1\\right)$-dimensional\ntopological phases. In previous studies, a torsional Chern-Simons term with a\ntemperature-squared ($T^2$) coefficient was proposed as an alternative action\nto describe thermal Hall effect with the idea of balancing the diffusion of\nheat by a torsional field. However, the question remains whether this action\nleads to local bulk thermal response which is not suppressed by the gap. In our\nhydrostatic effective action, we show that the $T^2$ bulk term is invariant\nunder variations up to boundary terms considering the back reaction of the\ngeometry on local temperature, which precisely describes the edge thermal\ncurrent. Furthermore, there is no boundary diffeomorphism anomalies and bulk\ninflow thermal currents at equilibrium and therefore no edge-to-edge adiabatic\nthermal current pumping. These results are in consistent with exponentially\nsuppressed thermal current for gapped phases.",
        "positive": "Finite-frequency counting statistics of electron transport: Markovian\n  Theory: We present a theory of frequency-dependent counting statistics of electron\ntransport through nanostructures within the framework of Markovian quantum\nmaster equations. Our method allows the calculation of finite-frequency current\ncumulants of arbitrary order, as we explicitly show for the second- and\nthird-order cumulants. Our formulae generalize previous zero-frequency\nexpressions in the literature and can be viewed as an extension of MacDonald's\nformula beyond shot noise. When combined with an appropriate treatment of\ntunneling, using, e.g. Liouvillian perturbation theory in Laplace space, our\nmethod can deal with arbitrary bias voltages and frequencies, as we illustrate\nwith the paradigmatic example of transport through a single resonant level\nmodel. We discuss various interesting limits, including the recovery of the\nfluctuation-dissipation theorem near linear response, as well as some drawbacks\ninherent of the Markovian description arising from the neglect of quantum\nfluctuations."
    },
    {
        "anchor": "Quantum oscillations and Berry's phase in topological insulator surface\n  states with broken particle-hole symmetry: Quantum oscillations can be used to determine properties of the Fermi surface\nof metals by varying the magnitude and orientation of an external magnetic\nfield. Topological insulator surface states are an unusual mix of normal and\nDirac fermions. Unlike in graphene and simple metals, Berry's geometric phase\nin topological insulator surface states is not necessarily quantised. We show\nthat reliably extracting this geometric phase from the phase offset associated\nwith the quantum oscillations is subtle. This is especially so in the presence\nof a Dirac gap such as that associated with the Zeeman splitting or interlayer\ntunneling. We develop a semi-classical theory for general mixed normal-Dirac\nsystems in the presence of a gap, and in doing so clarify the role of topology\nand broken particle-hole symmetry. We propose a systematic procedure of fitting\nLandau level index plots at large filling factors to reliably extract the phase\noffset associated with Berry's phase.",
        "positive": "Uncovering Exceptional Contours in non-Hermitian Hyperbolic Matter: Hyperbolic lattices are starting to be explored in search of novel phases of\nmatter. At the same time, non-Hermitian physics has come to the forefront in\nphotonic, optical, phononic, and condensed matter systems. In this work, we\nintroduce non-Hermitian hyperbolic matter and elucidate its exceptional\nproperties in depth. We use hyperbolic Bloch theory to investigate band\nstructures of hyperbolic lattices in the presence of non-Hermitian on-site gain\nand loss as well as non-reciprocal hopping. Using various analytical and\nnumerical approaches we demonstrate widely accessible and tunable exceptional\npoints and contours in {10,5} tessellations, which we characterize using phase\nrigidity, energy scaling, and vorticity. We further demonstrate the occurrence\nof higher-order exceptional points and contours in the {8,4} tessellations\nusing the method of Newton polygons, supported by vorticity and phase rigidity\ncomputations. Finally, we investigate the open boundary spectra and densities\nof states to compare with results from band theory, along with a demonstration\nof boundary localisation. Our results unveil an abundance of exceptional\ndegeneracies in hyperbolic non-Hermitian matter."
    },
    {
        "anchor": "Near field versus far field in radiative heat transfer between\n  two-dimensional metals: Using the standard fluctuational electrodynamics framework, we analytically\ncalculate the radiative heat current between two thin metallic layers,\nseparated by a vacuum gap. We analyse different contributions to the heat\ncurrent (travelling or evanescent waves, transverse electric or magnetic\npolarization) and reveal the crucial qualitative role played by the dc\nconductivity of the metals as compared to the speed of light. For poorly\nconducting metals, the heat current may be dominated by evanescent waves even\nwhen the separation between the layers greatly exceeds the thermal photon\nwavelength, and the coupling is of electrostatic nature. For well-conducting\nmetals, the evanescent contribution dominates at separations smaller than the\nthermal wavelength and is mainly due to magnetostatic coupling, in agreement\nwith earlier works on bulk metals.",
        "positive": "Field-induced Gap and Quantized Charge Pumping in Nano-helix: We propose several novel physical phenomena based on nano-scale helical\nwires. Applying a static electric field transverse to the helical wire induces\na metal to insulator transition, with the band gap determined by the applied\nvoltage. Similar idea can be applied to \"geometrically\" constructing\none-dimensional systems with arbitrary external potential. With a quadrupolar\nelectrode configuration, the electric field could rotate in the transverse\nplane, leading to a quantized dc charge current proportional to the frequency\nof the rotation. Such a device could be used as a new standard for the high\nprecession measurement of the electric current. The inverse effect implies that\npassing an electric current through a helical wire in the presence of a\ntransverse static electric field can lead to a mechanical rotation of the\nhelix. This effect can be used to construct nano-scale electro-mechanical\nmotors. Finally, our methodology also enables new ways of controlling and\nmeasuring the electronic properties of helical biological molecules such as the\nDNA."
    },
    {
        "anchor": "Dicke effect in a quantum wire with side-coupled quantum dots: A system of an array of side-coupled quantum-dots attached to a quantum wire\nis studied theoretically. Transport through the quantum wire is investigated by\nmeans of a noninteracting Anderson tunneling Hamiltonian. Analytical\nexpressions of the transmission probability and phase are given. The\ntransmission probability shows an energy spectrum with forbidden and allowed\nbands that depends on the up-down asymmetry of the system. In up-down symmetry\nonly the gap survives, and in up-down asymmetry an allowed band is formed. We\nshow that the allowed band arises by the indirect coupling between the up and\ndown quantum dots. In addition, the band edges can be controlled by the degree\nof asymmetry of the quantum dots. We discuss the analogy between this\nphenomenon with the Dicke effect in optics.",
        "positive": "Transition between ordinary and topological insulator regimes in\n  two-dimensional resonant magnetotransport: In the two-dimensional case the transition between ordinary and topological\ninsulator states can be described by a massive Dirac model with the mass term\nchanging its sign at the transition point. We theoretically investigate how\nsuch a transition manifests itself in resonant transport via localized helical\nedge states. The resonance occurs in the middle of the band gap due to a zero\nedge-state mode which is protected by the time-reversal symmetry, also when\ncoupled to the conducting leads. We obtain the explicit dependence of the\nresonant conductance on the mass parameter and an external magnetic field. The\nproposal may be of practical use, allowing one to determine the orbital\ng-factor of helical edge states in two-dimensional topological insulators."
    },
    {
        "anchor": "Discrete differential geometry and the properties of conformal\n  two-dimensional materials: Two-dimensional materials were first isolated no longer than ten years ago,\nand a comprehensive understanding of their properties under non-planar shapes\nis still being developed. Strictly speaking, the theoretical study of the\nproperties of graphene and other two-dimensional materials is the most complete\nfor planar structures and for structures with small deformations from\nplanarity. The opposite limit of large deformations is yet to be studied\ncomprehensively but that limit is extremely relevant because it determines\nmaterial properties near the point of failure. We are exploring uses for\ndiscrete differential geometry within the context of graphene and other\ntwo-dimensional materials, and these concepts appear promising in linking\nmaterials properties to shape regardless of how large a given material\ndeformation is. A brief account of additional contributions arising from our\ngroup to two-dimensional materials that include graphene, stanene and\nphosphorene is provided towards the end of this manuscript.",
        "positive": "Reduction of Phonon Lifetimes and Thermal Conductivity of a Carbon\n  Nanotube on Amorphous Silica: We use molecular dynamics simulations to examine the phonon lifetimes in\n(10,10) carbon nano-tubes (CNTs), both when isolated and when supported on\namorphous SiO2 substrates. We deter-mine the Umklapp, normal, boundary and\nCNT-substrate phonon scattering rates from the com-puted inverse lifetimes.\nSuspended CNTs have in-plane optical phonon lifetimes between 0.7-2 ps,\nconsistent with recent experiments, but contact with the substrate leads to a\nlifetime reduction to the 0.6-1.3 ps range. The thermal conductivity of the\nsupported CNT is also computed to be ~30 percent lower than that of the\nisolated CNT. The thermal boundary conductance estimated from the CNT-substrate\nphonon scattering rates is in good agreement with that computed from the\nGreen-Kubo relation and with previous experimental results. The results\nhighlight that solid substrates can strongly affect and could be even used to\ntune the thermal properties of CNTs."
    },
    {
        "anchor": "Effect of Inversion Asymmetry on Bilayer Graphene's Superconducting and\n  Exciton Condensates: Inversion asymmetry in bilayer graphene can be tuned by the displacement\nfield. As a result, the band dispersion in biased bilayer graphene acquires\nflat band regions near the Dirac points along with a non-trivial band geometry.\nWe analyze the effect of inversion symmetry on the critical temperature and\nsuperfluid stiffness of the superconducting state of AB-stacked graphene\nbilayer and on the exciton condensate in double layers formed by two AB-stacked\ngraphene bilayers. The geometric superfluid stiffness in bilayer graphene\nsuperconductors is found to be negligible due to the small superconducting gap.\nFurthermore, we show that the geometric superfluid stiffness is maximized for a\nconstant order parameter. Therefore, it can be neglected in biased bilayer\ngraphene superconductors with any pairing symmetry. However, the displacement\nfield enhances the geometric superfluid stiffness in exciton condensates. It is\nmost prominent at low densities and high displacement fields. A consequence of\nthe geometric superfluid stiffness is a modest enhancement of the\nBerezinskii-Kosterlitz-Thouless transition temperature in bilayer graphene's\nexciton condensate.",
        "positive": "Spin-resolved scattering through spin-orbit nanostructures in graphene: We address the problem of spin-resolved scattering through spin-orbit\nnanostructures in graphene, i.e., regions of inhomogeneous spin-orbit coupling\non the nanometer scale. We discuss the phenomenon of spin-double refraction and\nits consequences on the spin polarization. Specifically, we study the\ntransmission properties of a single and a double interface between a normal\nregion and a region with finite spin-orbit coupling, and analyze the\npolarization properties of these systems. Moreover, for the case of a single\ninterface, we determine the spectrum of edge states localized at the boundary\nbetween the two regions and study their properties."
    },
    {
        "anchor": "Tunable band gap in germanene by surface adsorption: Opening a sizable band gap in the zero-gap germanene without heavy loss of\ncarrier mobility is a key issue for its application in nanoelectronic devices\nsuch as high-performance field effect transistors (FETs) operating at room\ntemperature. Using the first-principles calculations, we find a band gap is\nopened at the Dirac point in germanene by single-side adsorption of alkali\nmetal (AM) atoms. This band gap is tunable by varying the coverage and the\nspecies of AM atoms, ranging from 0.02 to 0.31 eV, and the maximum global band\ngap is 0.26 eV. Since the effective masses of electrons and holes in germanene\nnear the Dirac point after surface adsorption (ranging from 0.005 to 0.106 me)\nare small, the carrier mobility is expected not to degrade much. Therefore\ngermanene is a potential candidate of effective FET channel operating at room\ntemperature upon surface adsorption.",
        "positive": "Entanglement production in chaotic quantum dots subject to spin-orbit\n  coupling: We study numerically the production of orbital and spin entangled states in\nchaotic quantum dots for non-interacting electrons. The introduction of\nspin-orbit coupling permit us to identify signatures of time-reversal symmetry\ncorrelations in the entanglement production previously unnoticed, resembling\nweak-(anti)localization quantum corrections to the conductance. We find the\nentanglement to be strongly dependent on spin-orbit coupling, showing universal\nfeatures for broken time-reversal and spin-rotation symmetries."
    },
    {
        "anchor": "Shot-Noise in Fractional Wires: a Universal Fano-Factor Different than\n  the Tunneling Charge: We consider partially gapped one dimensional (1D) conductors connected to\nnormal leads, as realized in fractional helical wires. At certain electron\ndensities, some distinct charge mode develops a gap due to electron\ninteractions, leading to a fractional conductance. For this state we study the\ncurrent noise caused by tunneling events inside the wire. We find that the\nnoise's Fano-factor is different from the tunneling charge. This fact arises\nfrom charge scattering at the wire-leads interfaces. The resulting noise is,\nhowever, universal - it depends only on the identification of the gapped mode,\nand is insensitive to additional interactions in the wire. We further show that\nthe tunneling charge can be deduced from the finite frequency noise, and yet is\ninteraction dependent due to screening effects.",
        "positive": "The influence of a strong infrared radiation field on the conductance\n  properties of doped semiconductors: This work presents an analytic angular differential cross section formula for\nthe electromagnetic radiation field assisted electron scattering by %% was on\nimpurities in semiconductors. These impurities are approximated with various\nmodel potentials. The scattered electrons are described by the well-known\nVolkov wave function, which has been used describe strong laser field matter\ninteraction for more than half a century, %% I would remove this time reference\nfor clarity which exactly describes the interaction of the electron with the\nexternal oscillating field. These calculations show that the electron\nconductance in a semiconductor could be enhanced by an order of magnitude if an\ninfrared electromagnetic field is present with $ 10^{11} < I < 10^{13}$\nW/cm$^2$ intensity."
    },
    {
        "anchor": "Time dependent configuration interaction simulations of spin swap in\n  spin orbit coupled double quantum dots: We perform time-dependent simulations of spin exchange for an electron pair\nin laterally coupled quantum dots. The calculation is based on configuration\ninteraction scheme accounting for spin-orbit (SO) coupling and\nelectron-electron interaction in a numerically exact way. Noninteracting\nelectrons exchange orientations of their spins in a manner that can be\nunderstood by interdot tunneling associated with spin precession in an\neffective SO magnetic field that results in anisotropy of the spin swap. The\nCoulomb interaction blocks the electron transfer between the dots but the spin\ntransfer and spin precession due to SO coupling is still observed. The\nelectron-electron interaction additionally induces an appearance of spin\ncomponents in the direction of the effective SO magnetic field which are\nopposite in both dots. Simulations indicate that the isotropy of the spin swap\nis restored for equal Dresselhaus and Rashba constants and properly oriented\ndots.",
        "positive": "Thermal nonlinearities in a nanomechanical oscillator: Nano- and micromechanical oscillators with high quality (Q) factors have\ngained much attention for their potential application as ultrasensitive\ndetectors. In contrast to micro-fabricated devices, optically trapped\nnanoparticles in vacuum do not suffer from clamping losses, hence leading to\nmuch larger Q-factors. We find that for a levitated nanoparticle the thermal\nenergy suffices to drive the motion of the nanoparticle into the nonlinear\nregime. First, we experimentally measure and fully characterize the frequency\nfluctuations originating from thermal motion and nonlinearities. Second, we\ndemonstrate that feedback cooling can be used to mitigate these fluctuations.\nThe high level of control allows us to fully exploit the force sensing\ncapabilities of the nanoresonator. Our approach offers a force sensitivity of\n20 zN $Hz^{-1/2}$, which is the highest value reported to date at room\ntemperature, sufficient to sense ultra-weak interactions, such as non-Newtonian\ngravity-like forces."
    },
    {
        "anchor": "Variational study of the nu=1 quantum Hall ferromagnet in the presence\n  of spin-orbit interaction: We investigate the nu=1 quantum Hall ferromagnet in the presence of\nspin-orbit coupling of the Rashba or Dresselhaus type by means of\nHartree-Fock-typed variational states. In the presence of Rashba (Dresselhaus)\nspin-orbit coupling the fully spin-polarized quantum Hall state is always\nunstable resulting in a reduction of the spin polarization if the product of\nthe particle charge $q$ and the effective $g$-factor is positive (negative). In\nall other cases an alternative variational state with O(2) symmetry and finite\nin-plane spin components is lower in energy than the fully spin-polarized state\nfor large enough spin-orbit interaction. The phase diagram resulting from these\nconsiderations differs qualitatively from earlier studies.",
        "positive": "Determination of spin-orbit interaction in semiconductor nanostructures\n  via non-linear transport: We investigate non-linear transport signatures stemming from linear and cubic\nspin-orbit interactions in one- and two-dimensional systems. The analytical\nzero-temperature response to external fields is complemented by finite\ntemperature numerical analysis, establishing a way to distinguish between\nlinear and cubic spin-orbit interactions. We also propose a protocol to\ndetermine the relevant material parameters from transport measurements\nattainable in realistic conditions, illustrated by values for Ge\nheterostructures. Our results establish a method for the fast benchmarking of\nspin-orbit properties in semiconductor nanostructures."
    },
    {
        "anchor": "Phonon-induced decoherence for a quantum dot spin qubit operated by\n  Raman passage: We study single-qubit gates performed via stimulated Raman adiabatic passage\n(STIRAP) on a spin qubit implemented in a quantum dot system in the presence of\nphonons. We analyze the interplay of various kinds of errors resulting from the\ncarrier-phonon interaction as well as from quantum jumps related to\nnonadiabaticity and calculate the fidelity as a function of the pulse\nparameters. We give quantitative estimates for an InAs/GaAs system and identify\nthe parameter values for which the error is considerably minimized, even to\nvalues below $10^{-4}$ per operation.",
        "positive": "Photonic Chern insulators made of gyromagnetic hyperbolic metamaterials: Controlling light propagation using artificial photonic crystals and\nelectromagnetic metamaterials is an important topic in the vibrant field of\nphotonics. Notably, chiral edge states on the surface or at the interface of\nphotonic Chern insulators can be used to make reflection-free waveguides. Here,\nby both theoretical analysis and electromagnetic simulations, we demonstrate\nthat gyromagnetic hyperbolic metamaterials (GHM) are photonic Chern insulators\nwith superior properties. As a novel mechanism, the simultaneous occurrence of\nthe hyperbolic and gyromagnetic effects in these metamaterials is shown to open\nthe large topological band gaps with gap Chern number of one. Importantly,\nunlike many other photonic Chern insulators, the GHM Chern insulators possess\nnon-radiative chiral edge modes on their surfaces, and thus allow to fabricate\nunidirectional waveguides without cladding metals which generally incurr\nconsiderable Ohmic loss. Furthermore, the photonic edge states in the proposed\nChern insulators are robust against disorder on a wide range of length scales,\nin strong contrast to crystalline topological insulators, and the light flow\ndirection on the surface of the Chern insulators can be easily flipped by\nswitching the direction of an applied magnetic field. Fascinatingly, we find\nthat negative refraction of the topological surface wave occurs at the boundary\nbetween the GHMs with the opposite signs of gyromagnetic parameters. Finally,\nwe show that compared with other photonic topological materials such as chiral\nhyperbolic materials, the present GHM Chern insulators can be much easier to\nfabricate."
    },
    {
        "anchor": "Coulomb Excitations for a Short Linear Chain of Metallic Shells: A self-consistent-field theory is given for the electronic collective modes\nof a chain containing a finite number, $N$, of Coulomb-coupled spherical\ntwo-dimensional electron gases (S2DE's) arranged with their centers along a\nstraight line, simulating a narrow micro-ribbon of metallic shells. The\nseparation between nearest-neighbor shells is arbitrary and because of the\nquantization of the electron energy levels due to their confinement to the\nspherical surface, all angular momenta $L$ of the Coulomb excitations and their\nprojections $M$ on the quantization axis are coupled. However, for incoming\nlight with a specific polarization, only one angular momentum quantum number is\nchosen. We show that when $N=3$ the next-nearest-neighbor Coulomb coupling is\nlarger than its value if they are located at opposite ends of a right-angle\ntriangle forming the triad. Additionally, the frequencies of the plasma\nexcitations depend on the orientation of the line joining them with respect to\nthe axis of quantization since the magnetic field generated from the induced\noscillating electric dipole moment on one sphere can couple to the induced\nmagnetic dipole moment on another.",
        "positive": "Statistics of delay times in mesoscopic systems as a manifestation of\n  eigenfunction fluctuations: We reveal a general explicit relation between the statistics of delay times\nin one-channel reflection from a mesoscopic sample of any spatial dimension and\nthe statistics of the eigenfunction intensities in its closed counterpart. This\nopens a possibility to use experimentally measurable delay times as a sensitive\nprobe of eigenfunction fluctuations. For the particular case of quasi-one\ndimensional geometry of the sample we use an alternative technique to derive\nthe probability density of partial delay times for any number of open channels."
    },
    {
        "anchor": "Evidence of a first-order quantum phase transition of excitons in\n  electron double layers: Complexity in many-particle systems occurs through processes of qualitative\ndifferentiation. These are described by concepts such as emerging states with\nspecific symmetries that are linked to order parameters. In quantum Hall phases\nof electrons in semiconductor double layers with large inter-layer electron\ncorrelation there is an emergent many body exciton phase with an order\nparameter that measures the condensate fraction of excitons across the\ntunneling gap. As the inter-layer coupling is reduced by application of an\nin-plane magnetic field, this excitonic insulating state is brought in\ncompetition with a Fermi-metal phase of composite fermions (loosely, electrons\nwith two magnetic flux quanta attached) stabilized by intra-layer electron\ncorrelation. Here we show that the quantum phase transformation between\nmetallic and excitonic insulating states in the coupled bilayers becomes\ndiscontinuous (first-order) by impacts of different terms of the\nelectron-electron interactions that prevail on weak residual disorder. The\nevidence is based on precise determinations of the excitonic order parameter by\ninelastic light scattering measurements close to the phase boundary. While\nthere is marked softening of low-lying excitations, our experiments underpin\nthe roles of competing orders linked to quasi-particle correlations in removing\nthe divergence of quantum fluctuations.",
        "positive": "Enhanced magnon spin transport in NiFe$_2$O$_4$ thin films on a\n  lattice-matched substrate: We investigate magnon spin transport in epitaxial nickel ferrite\n(NiFe$_2$O$_4$, NFO) films grown on magnesium gallate spinel (MgGa$_2$O$_4$,\nMGO) substrates, which have a lattice mismatch with NFO as small as 0.78%,\nresulting in the reduction of antiphase boundary defects and thus in improved\nmagnetic properties in the NFO films. In the nonlocal transport experiments,\nenhanced signals are observed for both electrically and thermally excited\nmagnons, and the magnon relaxation length ($\\lambda_m$) of NFO is found to be\naround 2.5 $\\mu$m at room temperature. Moreover, at both room and low\ntemperatures, we present distinct features from the nonlocal spin Seebeck\nsignals which arise from magnon polaron formation. Our results demonstrate\nexcellent magnon transport properties (magnon spin conductivity, $\\lambda_m$\nand spin mixing conductance at the interface between Pt) of NFO films grown on\na lattice-matched substrate that are comparable with those of yttrium iron\ngarnet."
    },
    {
        "anchor": "Current-induced bond rupture in single-molecule junctions: Effects of\n  multiple electronic states and vibrational modes: Current-induced bond rupture is a fundamental process in nanoelectronic\narchitectures such as molecular junctions and in scanning tunneling microscopy\nmeasurements of molecules at surfaces. The understanding of the underlying\nmechanisms is important for the design of molecular junctions that are stable\nat higher bias voltages and is a prerequisite for further developments in the\nfield of current-induced chemistry. In this work, we analyse the mechanisms of\ncurrent-induced bond rupture employing a recently developed method, which\ncombines the hierarchical equations of motion approach in twin space with the\nmatrix product state formalism, and allows accurate, fully quantum mechanical\nsimulations of the complex bond rupture dynamics. Extending previous work [J.\nChem. Phys. 154, 234702 (2021)], we consider specifically the effect of\nmultiple electronic states and multiple vibrational modes. The results obtained\nfor a series of models of increasing complexity show the importance of vibronic\ncoupling between different electronic states of the charged molecule, which can\nenhance the dissociation rate at low bias voltages profoundly.",
        "positive": "Universal probes of two-dimensional topological insulators: Dislocation\n  and pi-flux: We show that the pi-flux and the dislocation represent topological\nobservables that probe two-dimensional topological order through binding of the\nzero-energy modes. We analytically demonstrate that pi-flux hosts a Kramers\npair of zero modes in the topological Gamma (Berry phase skyrmion at the zero\nmomentum) and M (Berry phase skyrmion at a finite momentum) phases of the M-B\nmodel introduced for the HgTe quantum spin Hall insulator. Furthermore, we\nanalytically show that the dislocation acts as a pi-flux, but only so in the M\nphase. Our numerical analysis confirms this through a Kramers pair of zero\nmodes bound to a dislocation appearing in the M phase only, and further\ndemonstrates the robustness of the modes to disorder and the Rashba coupling.\nFinally, we conjecture that by studying the zero modes bound to dislocations\nall translationally distinguishable two-dimensional topological band insulators\ncan be classified."
    },
    {
        "anchor": "First Principles Calculation of Field Emission from Nanostructures using\n  Time-Dependent Density Functional Theory: a Simplified Approach: We introduce a new simplified method for computing the electron field\nemission current in short carbon nanotubes using ab-initio computation in\nperiodic simulation cells. We computed the evolution of the wave functions\nusing Time-Dependent Density Functional Theory, where we have utilized the\nCrank-Nicholson propagator. We found that in pristine carbon nanotubes, the\nemitted charge tends to emerge mostly from electrons that are concentrated at\nthe nanotube tip region. The charge beam concentrates into specific channel\nstructures, showing the utility of carbon nanotubes in precision emission\napplications.",
        "positive": "Hopf Semimetals: We construct two-band topological semimetals in four dimensions using the\nunstable homotopy of maps from the three-torus $T^3$ (Brillouin zone of a 3D\ncrystal) to the two-sphere $S^2$. Dubbed ``Hopf semimetals'', these gapless\nphases generically host nodal lines, with a surface enclosing such a nodal line\nin the four-dimensional Brillouin zone carrying a Hopf flux. These semimetals\nshow a unique class of surface states: while some three-dimensional surfaces\nhost gapless Fermi-arc states {\\em and} drumhead states, other surfaces have\ngapless Fermi surfaces. Gapless two-dimensional corner states are also present\nat the intersection of three-dimensional surfaces."
    },
    {
        "anchor": "Quantum spin Hall phase in GeSn heterostructures on silicon: Quantum phases of solid-state electron systems look poised to sustain exotic\nphenomena and a very rich spin physics. We propose a practical silicon-based\narchitecture that spontaneously sustains topological properties, while being\nfully compatible with the high-volume manufacturing capabilities of modern\nmicroelectronic foundries. Here we show how Ge1-xSnx alloys, an emerging group\nIV semiconductor, can be engineered into junctions that demonstrate a broken\ngap alignment. We predict such basic building block undergo a quantum phase\ntransition that can elegantly accommodate the existence of gate-controlled\nchiral edge states directly on Si. This will enable tantalizing prospects for\ndesigning integrated circuits hosting quantum spin hall insulators and advanced\ntopological functionalities.",
        "positive": "Counting statistics for electron capture in a dynamic quantum dot: We report non-invasive single-charge detection of the full probability\ndistribution $P_n$ of the initialization of a quantum dot with $n$ electrons\nfor rapid decoupling from an electron reservoir. We analyze the data in the\ncontext of a model for sequential tunneling pinch-off, which has generic\nsolutions corresponding to two opposing mechanisms. One limit considers\nsequential \"freeze out\" of an adiabatically evolving grand canonical\ndistribution, the other one is an athermal limit equivalent to the solution of\na generalized decay cascade model. We identify the athermal capturing mechanism\nin our sample, testifying to the high precision of our combined theoretical and\nexperimental methods. The distinction between the capturing mechanisms allows\nto derive efficient experimental strategies for improving the initialization."
    },
    {
        "anchor": "Network Models of Photonic Floquet Topological Insulators: A recently-proposed class of photonic topological insulators is shown to map\nonto Chalker-Coddington-type networks, which were originally formulated to\nstudy disordered quantum Hall systems. Such network models are equivalent to\nthe Floquet states of periodically-driven lattices. We show that they can\nexhibit topologically protected edge states even if all bands have zero Chern\nnumber, which is a characteristic property of Floquet bandstructures. These\nedge states can be counted by an adiabatic pumping invariant based on the\nwinding number of the coefficient of reflection from one edge of the network.",
        "positive": "Energy and phase relaxation in non-equilibrium diffusive nano-wires with\n  two-level systems: In recent experiments the non-equilibrium distribution function $f(E,U)$ in\ndiffusive Cu and Au quantum wires at a transport voltage $U$ shows scaling\nbehavior, $f(E,U)=f(E/eU)$, indicating a non-Fermi liquid interaction with {\\it\nnon-vanishing} T=0 scattering rate. The two-channel Kondo (2CK) effect,\npossibly produced by degenerate two-level systems, is known to exhibit such\nbehavior. Generalizing the auxiliary boson method to non-equilibrium, we\ncalculate $f(E,U)$ in the presence of 2CK impurities. We show that the 2CK\nequations reproduce the scaling form $f(E/eU)$. For all measured samples the\ntheoretical, scaled distribution functions coincide quantitatively with the\nexperimental results, the impurity concentration being the only adjustable\nparameter. This provides a microscopic explanation for the experiments and,\nconsidering that no other mechanism producing the scaling form is known to\ndate, lends strong evidence for the presence of degenerate two-level defects in\nthese systems. The relevance of these results for the problem of dephasing in\nmesoscopic wires is discussed."
    },
    {
        "anchor": "First Principles Analysis of Electron-Phonon Interaction in Graphene: The electron-phonon interaction in monolayer graphene is investigated by\nusing density functional perturbation theory. The results indicate that the\nelectron-phonon interaction strength is of comparable magnitude for all four\nin-plane phonon branches and must be considered simultaneously. Moreover, the\ncalculated scattering rates suggest an acoustic phonon contribution that is\nmuch weaker than previously thought, revealing the role of optical phonons even\nat low energies. Accordingly it is predicted, in good agreement with a recent\nmeasurement, that the intrinsic mobility of graphene may be more than an order\nof magnitude larger than the high values reported in suspended samples.",
        "positive": "Controlled parity switch of persistent currents in quantum ladders: We investigate the behavior of persistent currents for a fixed number of\nnoninteracting fermions in a periodic quantum ladder threaded by Aharonov-Bohm\nand transverse magnetic fluxes $\\Phi$ and $\\chi$. We show that the coupling\nbetween ladder legs provides a way to effectively change the ground-state\nfermion-number parity, by varying $\\chi$. Specifically, we demonstrate that\nvarying $\\chi$ by $2\\pi$ (one flux quantum) leads to an apparent fermion-number\nparity switch. We find that persistent currents exhibit a robust $4\\pi$\nperiodicity as a function of $\\chi$, despite the fact that $\\chi \\to \\chi +\n2\\pi$ leads to modifications of order $1/N$ of the energy spectrum, where $N$\nis the number of sites in each ladder leg. We show that these parity-switch and\n$4\\pi$ periodicity effects are robust with respect to temperature and disorder,\nand outline potential physical realizations using cold atomic gases and, for\nbosonic analogs of the effects, photonic lattices."
    },
    {
        "anchor": "Electronic, Optical and Mechanical Properties of Silicene Derivatives: Successful isolation of graphene from graphite opened a new era for material\nscience and con- densed matter physics. Due to this remarkable achievement,\nthere has been an immense interest to synthesize new two dimensional materials\nand to investigate their novel physical properties. Silicene, form of Si atoms\narranged in a buckled honeycomb geometry, has been successfully synthesized and\nemerged as a promising material for nanoscale device applications. However, the\nmajor obstacle for using silicene in electronic applications is the lack of a\nband gap similar to the case of graphene. Therefore, tuning the electronic\nproperties of silicene by using chemical functionalization methods such as\nhydrogenation, halogenation or oxidation has been a focus of interest in\nsilicene research. In this paper, we review the recent studies on the\nstructural, electronic, optical and mechanical proper- ties of\nsilicene-derivative structures. Since these derivatives have various band gap\nenergies, they are promising candidates for the next generation of electronic\nand optoelectronic device applications.",
        "positive": "Magnetic-field effect in the heterostructure\n  Ba$_{0.8}$Sr$_{0.2}$TiO$_3$/LaMnO$_3$: We have studied transport and magnetotransport properties of the\nheterostructure consisting of the ferroelectric Ba$_{0.8}$Sr$_{0.2}$TiO$_3$\nfilm deposited on the single crystalline manganite LaMnO$_3$. Two-dimensional\nelectron gas arising at the interface transforms the interface region of the\nantiferromagnetic manganite to the ferromagnetic state with the reoriented\nmagnetic moments. We obtained that the contribution of these ferromagnetic\nregions to the resistance of the heterostructure appears to be dependent on the\nexternal magnetic field applied perpendicularly to the interface (and parallel\nto {\\it c}-axis of the ferromagnetic state of LaMnO$_3$). We believe that the\ndecrease of the resistance of the studied heterostructure under the influence\nof the external magnetic field is caused by an appearance of the ferromagnetic\norder in the interface area. This leads to a relatively small resistance. In\nturn, the cycling of the applied magnetic field leads to the increase of the\nregions of the ferromagnetic order and, as a result, to decreasing scattering\nof the current carriers at the ferromagnetic disordering."
    },
    {
        "anchor": "Transport and thermoelectric properties of the LaAlO$_3$/SrTiO$_3$\n  interface: The transport and thermoelectric properties of the interface between\nSrTiO$_3$ and a 26-monolayer thick LaAlO$_3$-layer grown at high\noxygen-pressure have been investigated at temperatures from 4.2 K to 100 K and\nin magnetic fields up to 18 T. For $T>$ 4.2 K, two different electron-like\ncharge carriers originating from two electron channels which contribute to\ntransport are observed. We probe the contributions of a degenerate and a\nnon-degenerate band to the thermoelectric power and develop a consistent model\nto describe the temperature dependence of the thermoelectric tensor. Anomalies\nin the data point to an additional magnetic field dependent scattering.",
        "positive": "Dynamically Induced Exceptional Phases in Quenched Interacting\n  Semimetals: We report on the dynamical formation of exceptional degeneracies in basic\ncorrelation functions of non-integrable one- and two-dimensional systems\nquenched to the vicinity of a critical point. Remarkably, fine-tuned\nsemi-metallic points in the phase diagram of the considered systems are thereby\npromoted to topologically robust non-Hermitian (NH) nodal phases emerging in\nthe coherent long-time evolution of a dynamically equilibrating system. In the\nframework of non-equilibrium Green's function methods within the conserving\nsecond Born approximation, we predict observable signatures of these novel NH\nnodal phases in simple spectral functions as well as in the time-evolution of\nmomentum distribution functions."
    },
    {
        "anchor": "Two-dimensional magnetic nanoelectromechanical resonators: Two-dimensional (2D) layered materials possess outstanding mechanical,\nelectronic and optical properties, making them ideal materials for\nnanoelectromechanical applications. The recent discovery of 2D magnetic\nmaterials has promised a new class of magnetically active nanoelectromechanical\nsystems (NEMS). Here we demonstrate resonators made of 2D CrI3, whose\nmechanical resonances depend on the magnetic state of the material. We quantify\nthe underlining effects of exchange and anisotropy magnetostriction by\nmeasuring the field dependence of the resonance frequency under a magnetic\nfield parallel and perpendicular to the easy axis, respectively. Furthermore,\nwe show efficient strain tuning of magnetism in 2D CrI3 as a result of the\ninverse magnetostrictive effect using the NEMS platform. Our results establish\nthe basis for mechanical detection of magnetism and magnetic phase transitions\nin 2D layered magnetic materials. The new magnetic NEMS may also find\napplications in magnetic actuation and sensing.",
        "positive": "Quantum Pump for Fractional Charge: We propose a theoretical scenario for pumping of fractionally charged\nquasi-particle in the context of $\\nu=1/3$ fractional quantum Hall liquid. We\nconsider quasi-particle pumping across an anti-dot level tuned close to the\nresonance. Fractional charge pumping is achieved by slow and periodic\nmodulation of coupling of the anti-dot level to left and right moving edges of\na Hall bar set-up. This is attained by periodically modulating the gate\nvoltages controlling the couplings. In order to obtain quantization of pumped\ncharge in the unit of the electronic charge fraction ($\\nu e$) per pumping\ncycle in the adiabatic limit, we argue that the only possibility is to tune the\nquasi-particle operator to be irrelevant from being relevant in the\nrenormalization group sense, which can be accomplished by invoking quantum Hall\nline junctions into the Hall bar geometry. We also comment on possibility for\nexperimental realization of the above scenario."
    },
    {
        "anchor": "Anomalous Hall-like transverse magnetoresistance in Au thin films on\n  Y$_3$Fe$_5$O$_{12}$: Anomalous Hall-like signals in platinum in contact with magnetic insulators\nare common observations that could be explained by either proximity\nmagnetization or spin Hall magnetoresistance. In this work, longitudinal and\ntransverse magnetoresistances are measured in a pure gold thin film on the\nferrimagnetic insulator Y$_3$Fe$_5$O$_{12}$ (Yttrium Iron Garnet, YIG). We show\nthat both the longitudinal and transverse magnetoresistances have\nquantitatively consistent scaling in YIG/Au and in a YIG/Pt reference system\nwhen applying the Spin Hall magnetoresistance framework. No contribution of an\nanomalous Hall effect due to the magnetic proximity effect is evident.",
        "positive": "Valley-dependent Exciton Fine Structure and Autler-Townes Doublets from\n  Berry Phases in Monolayer Molybdenum Diselenide: The Berry phase of Bloch states can have profound effects on electron\ndynamics lead to novel transport phenomena, such as the anomalous Hall effect\nand the valley Hall effect. Recently, it was predicted that the Berry phase\neffect can also modify the exciton states in transition metal dichalcogenide\nmonolayers, and lift the energy degeneracy of exciton states with opposite\nangular momentum through an effective valley-orbital coupling. Here, we report\nthe first observation and control of the Berry-phase induced splitting of the\n2p-exciton states in monolayer molybdenum diselenide using the intraexciton\noptical Stark spectroscopy. We observe the time-reversal-symmetric analog of\nthe orbital Zeeman effect resulting from the valley-dependent Berry phase,\nwhich leads to energy difference of +14 (-14) meV between the $2p^+$ and $2p^-$\nexciton states in +K (-K) valley, consistent with the ordering from our ab\ninitio GW-BSE results. In addition, we show that the light-matter coupling\nbetween intraexciton states are remarkably strong, leading to prominent\nvalley-dependent Autler-Townes doublet under resonant driving. Our study opens\nup new pathways to coherently manipulate the quantum states and excitonic\nexcitation with infrared radiation in two-dimensional semiconductors."
    },
    {
        "anchor": "Turnstile pumping through an open quantum wire: We use a non-Markovian generalized master equation (GME) to describe the\ntime-dependent charge transfer through a parabolically confined quantum wire of\na finite length coupled to semi-infinite quasi two-dimensional leads. The\nquantum wire and the leads are in a perpendicular external magnetic field. The\ncontacts to the left and right leads depend on time and are kept out of phase\nto model a quantum turnstile of finite size. The effects of the driving period\nof the turnstile, the external magnetic field, the character of the contacts,\nand the chemical potential bias on the effectiveness of the charge transfer of\nthe turnstile are examined, both in the absence and in the presence of the\nmagnetic field. The interplay between the strength of the coupling and the\nstrength of the magnetic field is also discussed. We observe how the edge\nstates created in the presence of the magnetic field contribute to the pumped\ncharge.",
        "positive": "Molecular Switching Operation in Gate Constricted Interface of MoS$_2$\n  and hBN Heterostructure: Combined diverse two-dimensional (2D) materials for semiconductor interfaces\nare attractive for electrically controllable carrier confinement to enable\nexcellent electrostatic control. We investigated the transport characteristic\nin heterointerface of multilayer molybdenum disulfide and hexagonal boron\nnitride (MoS$_2$/h-BN) to reveal that the charge transfer switching (CTS) is\nhighly dependent on both the local gate constriction and bias in the channel.\nNotably, the CTS is shown to be controlled at a molecular level through\nelectrotunable gated constriction. The resulting significant change in\nconductance due to exposing 100 parts-per-billion of nitrogen dioxide gas led\nto a high on/off ratio of 10 2 for completely switching off the channel thus,\nacting as a molecular switch. First-principle calculations further explained\nthe mechanism of molecular CTS in the device. The molecular tunability of CTS\nhas not been previously reported in any of the van der Waals semiconductor\ninterfaces. Our finding opens avenues to exploit various atomically thin\nheterostructures for the mesoscopic transport phenomena towards molecular\nswitching operation at room temperature."
    },
    {
        "anchor": "Phenomenology of soft gap, zero bias peak, and zero mode splitting in\n  ideal Majorana nanowires: We theoretically consider the observed soft gap in the proximity-induced\nsuperconducting state of semiconductor nanowires in the presence of spin-orbit\ncoupling, Zeeman splitting, and tunneling leads, but in the absence of any\nextrinsic disorder. We critically consider the effects of three distinct\nintrinsic physical mechanisms (tunnel barrier to normal leads, temperature, and\ndissipation) on the phenomenology of the gap softness in the tunnel\nspectroscopy of the normal-superconductor junction as a function of spin\nsplitting and chemical potential. We find that all three mechanisms\nindividually can produce a soft gap, leading to calculated conductance spectra\nqualitatively mimicking experimental results. We also show that the\nphenomenology of the soft gap is intrinsically tied to the broadening and the\nheight of the Majorana zero mode(MZM)-induced differential conductance peak\nabove the topological quantum phase transition point with both the soft gap and\nthe quality of the MZM being simultaneously affected by tunnel barrier,\ntemperature, and dissipation. We establish that the MZM splitting oscillations\ncan be suppressed by temperature or dissipation, but not by the tunnel barrier.\nSince all three mechanisms are likely to be present in any realistic nanowires,\ndiscerning the effects of various mechanisms is difficult, necessitating\ndetailed experimental data as a function of all the system parameters, some of\nwhich (e.g., dissipation, chemical potential, tunnel barrier) may not be known\nexperimentally. While the tunneling-induced soft-gap behavior is benign with no\ndirect adverse effect on the Majorana topological properties with the zero-bias\npeak remaining quantized at $2e^2/h$, the soft gap induced by finite\ntemperature and/or finite dissipation is detrimental to topological properties\nand must be avoided as much as possible.",
        "positive": "Effect of quantum entanglement on Aharonov-Bohm oscillations,\n  spin-polarized transport and current magnification effect: We present a simple model of transmission across a metallic mesoscopic ring.\nIn one of its arm an electron interacts with a single magnetic impurity via an\nexchange coupling. We show that entanglement between electron and spin impurity\nstates leads to reduction of Aharonov-Bohm oscillations in the transmission\ncoefficient. The spin-conductance is asymmetric in the flux reversal as opposed\nto the two probe electrical conductance which is symmetric. In the same model\nin contradiction to the naive expectation of a current magnification effect, we\nobserve enhancement as well as the suppression of this effect depending on the\nsystem parameters. The limitations of this model to the general notion of\ndephasing or decoherence in quantum systems are pointed out."
    },
    {
        "anchor": "Domain-wall, overlap, and topological insulators: Topological insulators are a new class of materials which have gapped spectra\nin the bulk, but are accompanied by topologically protected gapless excitations\nat the surface (edge) of the system. These phenomena have a close relationship\nwith symmetry and dimensionality of the system through quantum anomalies. We\npoint out that such a surface state is a physical realization of the\ndomain-wall/overlap fermion. From this point of view, we discuss its\nimplications for experiments of topological insulators. We also discuss an\nunconventional overlap fermion, which is suggested by the \"periodic table\" of\ntopological insulators and superconductors.",
        "positive": "Auxiliary-level-assisted operations with charge qubits in semiconductors: We present a new scheme for rotations of a charge qubit associated with a\nsingly ionized pair of donor atoms in a semiconductor host. The logical states\nof such a qubit proposed recently by Hollenberg et al. are defined by the\nlowest two energy states of the remaining valence electron localized around one\nor another donor. We show that an electron located initially at one donor site\ncan be transferred to another donor site via an auxiliary molecular level\nformed upon the hybridization of the excited states of two donors. The electron\ntransfer is driven by a single resonant microwave pulse in the case that the\nenergies of the lowest donor states coincide or two resonant pulses in the case\nthat they differ from each other. Depending on the pulse parameters, various\none-qubit operations, including the phase gate, the NOT gate, and the Hadamard\ngate, can be realized in short times. Decoherence of an electron due to the\ninteraction with acoustic phonons is analyzed and shown to be weak enough for\ncoherent qubit manipulation being possible, at least in the proof-of-principle\nexperiments on one-qubit devices."
    },
    {
        "anchor": "The signature of a double quantum-dot structure in the I-V\n  characteristics of a complex system: We demonstrate that by carefully analyzing the temperature dependent\ncharacteristics of the I-V measurements for a given complex system it is\npossible to determine whether it is composed of a single, double or multiple\nquantum-dot structure. Our approach is based on the orthodox theory for a\ndouble-dot case and is capable of simulating I-V characteristics of systems\nwith any resistance and capacitance values and for temperatures corresponding\nto thermal energies larger than the dot level spacing. We compare I-V\ncharacteristics of single-dot and double-dot systems and show that for a given\nmeasured I-V curve considering the possibility of a second dot is equivalent to\ndecreasing the fit temperature. Thus, our method allows one to gain information\nabout the structure of an experimental system based on an I-V measurement.",
        "positive": "Linear magneto-resistance versus weak antilocalization effects in\n  Bi$_2$Te$_3$ films: In chalcogenide topological insulator materials, two types of\nmagneto-resistance (MR) effects are widely discussed: a positive MR dip around\nzero magnetic field associated with the weak antilocalization (WAL) effect and\na linear MR effect which generally persists to high fields and high\ntemperatures. We have studied the MR of topological insulator Bi2Te3 films from\nthe metallic to semiconducting transport regime. While in metallic samples, the\nWAL is difficult to identify due to the smallness of the WAL compared to the\nsamples' conductivity, the sharp WAL dip in the MR is clearly present in the\nsamples with higher resistivity. To correctly account for the low field MR by\nthe quantitative theory of WAL according to the Hikami-Larkin-Nagaoka (HLN)\nmodel, we find that the classical (linear) MR effect should be separated from\nthe WAL quantum correction. Otherwise the WAL fitting alone yields an\nunrealistically large coefficient $\\alpha$ in the HLN analysis."
    },
    {
        "anchor": "Majorana corner modes and flat-band Majorana edge modes in\n  superconductor/topological-insulator/superconductor junctions: Recently, superconductors with higher-order topology have stimulated\nextensive attention and research interest. Higher-order topological\nsuperconductors exhibit unconventional bulk-boundary correspondence, thus allow\nexotic lower-dimensional boundary modes, such as Majorana corner and hinge\nmodes. However, higher-order topological superconductivity has yet to be found\nin naturally occurring materials. In this work, we investigate higher-order\ntopology in a two-dimensional Josephson junction comprised of two $s$-wave\nsuperconductors separated by a topological insulator thin film. We found that\nzero-energy Majorana corner modes, a boundary fingerprint of higher-order\ntopological superconductivity, can be achieved by applying magnetic field. When\nan in-plane Zeeman field is applied to the system, two corner states appear in\nthe superconducting junction. Furthermore, we also discover a two dimensional\nnodal superconducting phase which supports flat-band Majorana edge modes\nconnecting the bulk nodes. Importantly, we demonstrate that zero-energy\nMajorana corner modes are stable when increasing the thickness of topological\ninsulator thin film.",
        "positive": "Giant Photocurrent Enhancement by Coulomb Interaction in a Single\n  Quantum Dot for Energy Harvesting: Understanding the carrier excitation and transport processes at the\nsingle-charge level plays a key role in quantum-dot-based solar cells and\nphotodetectors. Here, we report on Coulomb-induced giant photocurrent\nenhancement of positive charged trions (\\emph{X$^+$}) in a single\nself-assembled InAs/GaAs quantum dot embedded in an \\emph{n-i-}Schottky device\nby high-resolution photocurrent (PC) spectroscopy. The Coulomb repulsion\nbetween the two holes in the \\emph{X$^+$} increases the tunneling rate of the\nhole, and the remaining hole can be reused as the initial state to regenerate\n\\emph{X$^+$} again. This process brings the PC amplitude of \\emph{X$^+$} up to\n30 times larger than that of the neutral exciton. The analysis of the hole\ntunneling time gives the equivalent change of hole tunnel barriers caused by\nCoulomb interaction between two holes with a value of 8.05 meV during the\ntunneling process. Our work brings a fundamental understanding of energy\nconversion for solar cells in nanoscale to improve internal quantum efficiency\nfor energy harvesting."
    },
    {
        "anchor": "Coupling and coherent electrical control of two dopants in a silicon\n  nanowire: Electric control of individual atoms or molecules in a solid-state system\noffers a promising way to bring quantum mechanical functionalities into\nelectronics. This idea has recently come into the reach of the established\ndomain of silicon technology, leading to the realization of single-atom\ntransistors and to the first measurements of electron spin dynamics in single\ndonors. Here we show that we can electrically couple two donors embedded in a\nmulti-gate silicon transistor, and induce coherent oscillations in their charge\nstates by means of microwave signals. We measure single-electron tunneling\nacross the two donors, which reveals their energy spectrum. The lowest energy\nstates, corresponding to a single electron located on either of the two donors,\nform a two-level system (TLS) well separated from all other electronic levels.\nGigahertz driving of this TLS results in a quantum interference pattern\nassociated with the absorption or the stimulated emission of up to ten\nmicrowave photons. We estimate a charge dephasing time of 0.3 nanoseconds,\nconsistent with other types of charge quantum bits. Here, however, the\nrelatively short coherence time can be counterbalanced by fast operation\nsignals (in principle up to 1 terahertz) as allowed by the large empty energy\nwindow separating ground and excited states in donor atoms. The demonstrated\ncoherent coupling of two donors constitutes an essential step towards\ndonor-based quantum computing devices in silicon.",
        "positive": "Theory of Transport Phenomena in Coherent Quantum Hall Bilayers: We argue that all anomalous transport properties of coherent quantum quantum\nHall bilayers can be understood in terms of a mean-field transport theory in\nwhich the condensate phase is nearly uniform across the sample, and the\nstrength of condensate coupling to interlayer tunneling processes is\nsubstantially reduced compared to the predictions of disorder-free microscopic\nmean-field theory. These ingredients provide a natural explanation for recently\nestablished I-V characteristics which feature a critical current above which\nthe tunneling resistance abruptly increases and a non-local interaction between\ninterlayer tunneling at the inner and outer edges of Corbino rings. We propose\na microscopic picture in which disorder is the main agent responsible for the\nreduction of the effective interlayer tunneling strength."
    },
    {
        "anchor": "Schottky Electric Field Induced Circular Photogalvanic Effect in Cd3As2\n  Nanobelts: Dirac semimetals are expected to forbid the manifestation of the circular\nphotogalvanic effect (CPGE) because of their crystal inversion symmetry. Here,\nwe report the observation of the CPGE in Cd3As2 nanobelt field effect\ntransistors, when the photoexcitation is focused in the vicinity of the metal\ncontacts up to room temperature. We attribute the CPGE to the Schottky electric\nfield induced symmetry breaking, which results in the photocurrent modulation\nby circularly polarized photoexcitation via spin-momentum locking. The\nhypothesis is supported by a suite of experiments including spatially and\nangularly resolved helicity dependent photocurrent, Kelvin probe force\nmicroscopy, and gate voltage dependence. First principles calculations\nconfirmed a topological phase transition upon field induced structural\ndistortion. This work provides key insights on the electrically controlled\nhelicity dependent optoelectronics in Dirac materials.",
        "positive": "Approach to Dark Spin Cooling in a Diamond Nanocrystal: Using a Hartman-Hahn protocol, we demonstrate spin polarization transfer from\na single, optically-polarized nitrogen-vacancy (NV) center to the ensemble of\nparamagnetic defects hosted by an individual diamond nanocrystal. Owing to the\nstrong NV-bath coupling, the transfer takes place on a short, microsecond time\nscale. Upon fast repetition of the pulse sequence we observe strong\npolarization transfer blockade, which we interpret as an indication of spin\nbath cooling. Numerical simulations indicate that the spin bath polarization is\nnon-uniform throughout the nanoparticle averaging approximately 5% over the\ncrystal volume, but reaching up to 25% in the immediate vicinity of the NV.\nThese observations may prove relevant to the planning of future bath-assisted\nmagnetometry tests."
    },
    {
        "anchor": "Collision fragmentation of aggregates. The role of the interaction\n  potential between comprising particles: We investigate disruptive collisions of aggregates comprised of particles\nwith different interaction potentials. We study Lennard-Jones (L-J), Tersoff,\nmodified L-J potential and the one associated with Johnson-Kendall-Roberts\n(JKR) model. These refer to short, middle and long-ranged inter-particle\npotentials and describe both inter-atomic interactions and interactions of\nmacroscopic adhesive bodies. We perform comprehensive molecular dynamics\nsimulations and observe for all four potentials power-law dependencies for the\nsize distribution of collision fragments and for their size-velocity\ncorrelation. We introduce a new fragmentation characteristic -- the shattering\ndegree $S$, quantifying the fraction of monomers in debris and reveal its\nuniversal behavior. Namely, we demonstrate that for all potentials, $1-S$ is\ndescribed by a universal function of the impact velocity. Using the above\nresults, we perform the impact classification and construct the respective\ncollision phase diagram. Finally, we present a qualitative theory that explains\nthe observed scaling behavior.",
        "positive": "Blocking transition of interface traps in MoS$_2$-on-SiO$_2$ FETs: Electrical conductivity with gate-sweep in a few layer MoS$_2$-on-SiO$_2$\nfield-effect-transistor shows an abrupt reduction in hysteresis when cooled.\nThe hysteresis and time dependent conductivity of the MoS$_2$ channel are\nmodeled using the dynamics of interface traps' occupancy. The reduction in\nhysteresis is found to be steepest at a blocking temperature near 225 K. This\nis attributed to the interplay between thermal and barrier energies and fitted\nusing a distribution of the latter. Further, the charge stored in the blocked\ntraps is programmed at low temperatures by cooling under suitable gate voltage.\nThus the threshold gate-voltage in nearly non-hysteretic devices at 80 K\ntemperature is reversibly controlled over a wide range."
    },
    {
        "anchor": "Subperiods and apparent pairing in integer quantum Hall interferometers: We analyze the magnetic field and gate voltage dependence of the longitudinal\nresistance in an integer quantum Hall Fabry-P\\'{e}rot interferometer, taking\ninto account the interactions between an interfering edge mode, a\nnon-interfering edge mode and the bulk. For weak bulk-edge coupling and\nsufficiently strong inter-edge interaction, we obtain that the interferometer\noperates in the Aharonov-Bohm regime with a flux periodicity halved with\nrespect to the usual expectation. Even in the regime of strong bulk-edge\ncoupling, this behavior can be observed as a subperiodicity of the interference\nsignal in the Coulomb dominated regime. We do not find evidence for a\nconnection between a reduced flux period and electron pairing, though. Our\nresults can reproduce some recent experimental findings.",
        "positive": "Mode splitting of spin waves in magnetic nanotubes with discrete\n  symmetries: We investigate how geometry influences spin dynamics in polygonal magnetic\nnanotubes. We find that lowering the rotational symmetry of nanotubes by\ndecreasing the number of planar facets, splits an increasing number of\nspin-wave modes, which are doubly degenerate in cylindrical tubes. This\nsymmetry-governed splitting is distinct form the topological one recently\nobserved in cylindrical nanotubes. Doublet modes with half-integer or integer\nmultiple azimuthal periods of the number of facets, split to singlet pairs with\nlateral standing-wave profiles of opposing mirror-plane symmetries.\nFurthermore, the polygonal geometry facilitates the hybridization of modes with\ndifferent azimuthal periods but the same symmetry, manifested in avoided level\ncrossings. These phenomena, unimaginable in cylindrical geometry, provide new\ntools to control spin dynamics on nanoscale. The presented concept can be\ngeneralized to nano-objects of versatile geometries and order parameters,\noffering new routes to engineer dynamic response in nanoscale devices."
    },
    {
        "anchor": "Spin torque contribution to the a.c. spin Hall conductivity: Using the recently proposed definition of a conserved spin-current operator\n[J. Shi et al., Phys. Rev. Lett. 96, 076604 (2006)] we explore the frequency\ndependent spin Hall conductivity for a two-dimensional electron gas with Rashba\nand Dresselhaus spin-orbit interaction in response to an oscillating electric\nfield. We show that the optical spectrum of the spin Hall conductivity exhibit\nremarkable changes when the new definition of spin current is applied. Such\nbehavior is mainly due to a significant contribution of the spin torque term\nwhich is absent in the conventional form of the spin current. In addition, it\nis observed that the magnitude and direction of the dynamic spin Hall current\nstrongly depends on the electric field frequency as with the interplay of the\nspin-orbit coupling strengths.",
        "positive": "Quantum pumping induced by disorder in one dimension: The topological property in one dimension (1D) is protected by symmetry.\nBased on a concrete model, we show that since a 1D topological model usually\ncontain two of the three Pauli matrix, the left one automatically become the\nprotecting symmetry. We study the effect of disorder preserving or breaking the\nsymmetry and show the nature of symmetry protecting in the 1D topological\nphase. Based on the 1D topological model, a stable quantum pumping can be\nconstructed, which is topologically nontrivial and can be characterized by the\nChern number. By calculating the instantaneous local current we show that an\ninteger charge is pumped across a periodic chain in a cyclic process. Also on\nan open chain, an edge state can be transferred to the other edge by the\nquantum pumping. Furthermore we find that not only the quantum pumping is\nstable to on-site disorder, but also can be induced by it. These results may be\nrealized experimentally using quasicrystals."
    },
    {
        "anchor": "Irreducible momentum-space spin structure of Weyl semimetals and its\n  signatures in Friedel oscillations: Materials that break time-reversal or inversion symmetry possess\nnondegenerate electronic bands, which can touch at so-called Weyl points. The\nspinor eigenstates in the vicinity of a Weyl point exhibit a well-defined\nchirality $\\pm 1$. Numerous works have studied the consequences of this\nchirality, for example in unconventional magnetoelectric transport. However,\neven a Weyl point with isotropic dispersion is not only characterized by its\nchirality but also by the momentum dependence of the spinor eigenstates. For a\nsingle Weyl point, this momentum-space spin structure can be brought into\nstandard \"hedgehog\" form by a unitary transformation, but for two or more Weyl\npoints, this is not possible. In this work, we show that the relative spin\nstructure of a pair of Weyl points has strong qualitative signatures in the\nelectromagnetic response. Specifically, we investigate the Friedel oscillations\nin the induced charge density due to a test charge for a centrosymmetric system\nconsisting of two Weyl points with isotropic dispersion. The most pronounced\nsignature is that the amplitude of the Friedel oscillations falls off as\n$1/r^4$ in directions in which both Weyl points exhibit the same spin\nstructure, while for directions with inverted spin structures, the amplitude of\nthe Friedel oscillations decreases as $1/r^3$.",
        "positive": "Enabling Adiabatic Passages Between Disjoint Regions in Parameter Space\n  through Topological Transitions: We explore topological transitions in parameter space in order to enable\nadiabatic passages between regions adiabatically disconnected within a given\nparameter manifold. To this end, we study the Hamiltonian of two coupled qubits\ninteracting with external magnetic fields, and make use of the analogy between\nthe Berry curvature and magnetic fields in parameter space, with spectrum\ndegeneracies associated to magnetic charges. Symmetry-breaking terms induce\nsharp topological transitions on these charge distributions, and we show how\none can exploit this effect to bypass crossing degeneracies. We also\ninvestigate the curl of the Berry curvature, an interesting but as of yet not\nfully explored object, which together with its divergence uniquely defines this\nfield. Finally, we suggest a simple method for measuring the Berry curvature,\nthereby showing how one can experimentally verify our results."
    },
    {
        "anchor": "Effect of Rashba splitting on RKKY interaction in topological insulator\n  thin films: In this work we have investigated the effect of Rashba splitting on the RKKY\ninteraction in TI thin film both at finite and zero chemical potential. We find\nthat the spin susceptibility of Rashba materials including TI thin film is\nstrongly dependent on the direction of distance vector. Moreover, we find\nanother term in the off-diagonal terms of the spin-susceptibility tensor which\nin contrast to the well-known DM-like term is symmetric. We show how one can\ntune the RKKY interaction by using electric field applied perpendicularly to\nthe surface plane and by small chemical doping giving rise to enhance the RKKY\nterm, drastically. We have presented our results for two different situations,\nnamely inter-surface pairing of magnetic impurities as well as intra-surface\none. The behavior of these two situations is completely different which we\ndescribe it by mapping the density of states of each surface on the band\ndispersion.",
        "positive": "The Kondo Temperature of SU(4) Symmetric Quantum Dots: A path integral approach is used to derive a closed analytical expression for\nthe Kondo temperature of the SU(4) symmetrical Anderson model. In contrast to\nthe SU(2) case, the prefactor of the Kondo temperature is found to display a\npeculiar orbital energy (gate voltage) dependence, reflecting the presence of\nvarious SU(4) mixed valence fixed points. Our analytical expressions are tested\nagainst and confirmed by numerical renormalization group computations."
    },
    {
        "anchor": "Evidence of topological superconductivity in planar Josephson junctions: Majorana zero modes are quasiparticle states localized at the boundaries of\ntopological superconductors that are expected to be ideal building blocks for\nfault-tolerant quantum computing. Several observations of zero-bias conductance\npeaks measured in tunneling spectroscopy above a critical magnetic field have\nbeen reported as experimental indications of Majorana zero modes in\nsuperconductor/semiconductor nanowires. On the other hand, two dimensional\nsystems offer the alternative approach to confine Ma jorana channels within\nplanar Josephson junctions, in which the phase difference {\\phi} between the\nsuperconducting leads represents an additional tuning knob predicted to drive\nthe system into the topological phase at lower magnetic fields. Here, we report\nthe observation of phase-dependent zero-bias conductance peaks measured by\ntunneling spectroscopy at the end of Josephson junctions realized on a InAs/Al\nheterostructure. Biasing the junction to {\\phi} ~ {\\pi} significantly reduces\nthe critical field at which the zero-bias peak appears, with respect to {\\phi}\n= 0. The phase and magnetic field dependence of the zero-energy states is\nconsistent with a model of Majorana zero modes in finite-size Josephson\njunctions. Besides providing experimental evidence of phase-tuned topological\nsuperconductivity, our devices are compatible with superconducting quantum\nelectrodynamics architectures and scalable to complex geometries needed for\ntopological quantum computing.",
        "positive": "Full frequency voltage noise spectral density of a single electron\n  transistor: We calculate the full frequency spectral density of voltage fluctuations in a\nSingle Electron Transistor (SET), used as an electrometer biased above the\nCoulomb threshold so that the current through the SET is carried by sequential\ntunnel events. We consider both a normal state SET and a superconducting SET.\nThe whole spectrum from low frequency telegraph noise to quantum noise at\nfrequencies comparable to the SET charging energy $(E_{C}/\\hbar)$, and high\nfrequency Nyquist noise is described. We take the energy exchange between the\nSET and the measured system into account using a real-time diagrammatic Keldysh\ntechnique. The voltage fluctuations determine the back-action of the SET onto\nthe measured system and we specifically discuss the case of superconducting\ncharge qubit read-out and measuring the so-called Coulomb staircase of a single\nCooper pair box."
    },
    {
        "anchor": "Cross-plane enhanced thermoelectricity and phonon suppression in\n  graphene/MoS2 van der Waals heterostructures: The thermoelectric figures of merit of pristine two-dimensional materials are\npredicted to be significantly less than unity, making them uncompetitive as\nthermoelectric materials. Here we elucidate a new strategy that overcomes this\nlimitation by creating multi-layer nanoribbons of two different materials and\nallowing thermal and electrical currents to flow perpendicular to their planes.\nTo demonstrate this enhancement of thermoelectric efficiency ZT, we analyse the\nthermoelectric performance of monolayer molybdenum disulphide (MoS2) sandwiched\nbetween two graphene monolayers and demonstrate that the cross-plane (CP) ZT is\nsignificantly enhanced compared with the pristine parent materials. For the\nparent monolayer of MoS2, we find that ZT can be as high as approximately 0.3,\nwhereas monolayer graphene has a negligibly small ZT. In contrast for the\ngraphene/MoS2/graphene heterostructure, we find that the CP ZT can be as large\nas 2.8. One contribution to this enhancement is a reduction of the thermal\nconductance of the van der Waals heterostructure compared with the parent\nmaterials, caused by a combination of boundary scattering at the MoS2/graphene\ninterface which suppresses the phonons transmission and the lower Debye\nfrequency of monolayer MoS2, which filters phonons from the monolayer graphene.\nA second contribution is an increase in the electrical conductance and Seebeck\ncoefficient associated with molybdenum atoms at the edges of the nanoribbons.",
        "positive": "Charge and spin transport on graphene grain boundaries in a quantizing\n  magnetic field: We study charge and spin transport along grain boundaries in single layer\ngraphene in the presence of a quantizing magnetic field. Transport states in a\ngrain boundary are produced by hybridization of Landau zero modes with\ninterfacial states. In selected energy regimes quantum Hall edge states can be\ndeflected either fully or partially into grain boundary states. The degree of\nedge state deflection is studied in the nonlocal conductance and in the shot\nnoise. We also consider the possibility of grain boundaries as gate-switchable\nspin filters, a functionality enabled by counterpropagating transport channels\nlaterally confined in the grain boundary."
    },
    {
        "anchor": "Large, tunable valley splitting and single-spin relaxation mechanisms in\n  a Si/Si$_x$Ge$_{1-x}$ quantum dot: Valley splitting is a key figure of silicon-based spin qubits. Quantum dots\nin Si/SiGe heterostructures reportedly suffer from a relatively low valley\nsplitting, limiting the operation temperature and the scalability of such qubit\ndevices. Here, we demonstrate a robust and large valley splitting exceeding 200\n$\\mu$eV in a gate-defined single quantum dot, hosted in molecular-beam\nepitaxy-grown $^{28}$Si/SiGe. The valley splitting is monotonically and\nreproducibly tunable up to 15 % by gate voltages, originating from a 6 nm\nlateral displacement of the quantum dot. We observe static spin relaxation\ntimes $T_1>1$ s at low magnetic fields in our device containing an integrated\nnanomagnet. At higher magnetic fields, $T_1$ is limited by the valley hotspot\nand by phonon noise coupling to intrinsic and artificial spin-orbit coupling,\nincluding phonon bottlenecking.",
        "positive": "Andreev experiments on superconductor/ferromagnet point contacts: Andreev reflection is a smart tool to investigate the spin polarisation P of\nthe current through point contacts between a superconductor and a ferromagnet.\nWe compare different models to extract P from experimental data and investigate\nthe dependence of P on different contact parameters."
    },
    {
        "anchor": "Quantized one-dimensional edge channels with strong spin-orbit coupling\n  in 3D topological insulators: A strong coupling between the electron spin and its motion is one of the\nprerequisites of spin-based data storage and electronics. A major obstacle is\nto find spin-orbit coupled materials where the electron spin can be probed and\nmanipulated on macroscopic length scales, for instance across the gate channel\nof a spin-transistor. Here, we report on millimeter-scale edge channels with a\nconductance quantized at a single quantum 1 $\\times$ $e^2/h$ at zero magnetic\nfield. The quantum transport is found at the lateral edges of three-dimensional\ntopological insulators made of bismuth chalcogenides. The data are explained by\na lateral, one-dimensional quantum confinement of non-topological surface\nstates with a strong Rashba spin-orbit coupling. This edge transport can be\nswitched on and off by an electrostatic field-effect. Our results are\nfundamentally different from an edge transport in quantum spin Hall insulators\nand quantum anomalous Hall insula-tors.",
        "positive": "Can the conductance of an adiabatic ballistic constriction be lower than\n  $2e^2/h$?: We have performed four-terminal conductance measurements of a one-dimensional\n(1D) channel in which it is possible to modulate the potential profile using\nthree overlaying finger gates. In such a 1D ballistic structure we have\nobserved, {\\em for the first time,} that the conductance steps show a gradual\ndecrease from $2e^2/h$ to $0.97 \\times 2e^2/h$ with increasing negative finger\ngate voltage in a short, clean 1D constriction. We suggest this phenomenon is\ndue to differing shifts of 1D subbands with changing spilt-gate voltage. Both a\nsimple analytical estimate for an adiabatic constriction and, realistic\nmodeling of the device, give the same magnitude of the conductance decrease as\nobserved in our experiments."
    },
    {
        "anchor": "Nuclear spin effect in metallic spin valve: We study electronic transport through a ferromagnet normal-metal ferromagnet\nsystem and we investigate the effect of hyperfine interaction between electrons\nand nuclei in the normal-metal part. A switching of the magnetization\ndirections of the ferromagnets causes nuclear spins to precess. We show that\nthe effect of this precession on the current through the system is large enough\nto be observed in experiment.",
        "positive": "Moving crystal phases of a quantum Wigner solid in an ultra-high-quality\n  2D electron system: In low-disorder, two-dimensional electron systems (2DESs), the fractional\nquantum Hall states at very small Landau level fillings ($\\nu$) terminate in a\nWigner solid (WS) phase, where electrons arrange themselves in a periodic\narray. The WS is typically pinned by the residual disorder sites and manifests\nan insulating behavior, with non-linear current-voltage (\\textit{I-V}) and\nnoise characteristics. We report here, measurements on an ultra-low-disorder,\ndilute 2DES, confined to a GaAs quantum well. In the $\\nu < 1/5$ range,\nsuperimposed on a highly-insulating longitudinal resistance, the 2DES exhibits\na developing fractional quantum Hall state at $\\nu=1/7$, attesting to its\nexceptional high quality, and dominance of electron-electron interaction in the\nlow filling regime. In the nearby insulating phases, we observe remarkable\nnon-linear \\textit{I-V} and noise characteristics as a function of increasing\ncurrent, with current thresholds delineating three distinct phases of the WS: a\npinned phase (P1) with very small noise, a second phase (P2) in which $dV/dI$\nfluctuates between positive and negative values and is accompanied by very high\nnoise, and a third phase (P3) where $dV/dI$ is nearly constant and small, and\nnoise is about an order of magnitude lower than in P2. In the depinned (P2 and\nP3) phases, the noise spectrum also reveals well-defined peaks at frequencies\nthat vary linearly with the applied current, suggestive of washboard\nfrequencies. We discuss the data in light of a recent theory that proposes\ndifferent dynamic phases for a driven WS."
    },
    {
        "anchor": "Spin-blockade spectroscopy of a two-level artificial molecule: Coulomb and spin blockade spectroscopy investigations have been performed on\nan electrostatically defined ``artificial molecule'' connected to spin\npolarized leads. The molecule is first effectively reduced to a two-level\nsystem by placing both constituent atoms at a specific location of the level\nspectrum. The spin sensitivity of the conductance enables us to identify the\nelectronic spin-states of the two-level molecule. We find in addition that the\nmagnetic field induces variations in the tunnel coupling between the two atoms.\nThe lateral nature of the device is evoked to explain this behavior.",
        "positive": "Electronic transport and the localization length in the quantum Hall\n  effect: We report on recent experimental results from transport measurements with\nlarge Hall bars made of high mobility GaAs/AlGaAs heterostructures. Thermally\nactivated conductivities and hopping transport were investigated in the integer\nquantum Hall regime. The predominant transport processes in two dimensions are\ndiscussed. The implications of transport regime on prefactor universality and\non the relation between $\\rho_{xx}$ and $\\rho_{xy}$ are studied. Particularly\nin the Landau level tails, strictly linear dependence\n$\\delta\\rho_{xy}(\\rho_{xx})$ was found, with pronounced asymmetries with\nrespect to the plateau centre. At low temperatures, Ohmic (temperature\ndependent) as well as non-Ohmic (current dependent) transport were investigated\nand analysed on the basis of variable-range hopping theory. The non-Ohmic\nregime could successfully be described by an effective electron temperature\nmodel. The results from either the Ohmic transport or from a comparison of\nOhmic and non-Ohmic data allowed to determine the localization length $\\xi$ in\ntwo different ways. The observed divergence of $\\xi(\\nu)$ with the filling\nfactor $\\nu$ approaching a Landau level centre, is in qualitative agreement\nwith scaling theories of electron localization. The absolute values of $\\xi$\nfar from the $\\rho_{xx}$ peaks are compared with theoretical predictions. On\none hand, discrepancies between the $\\xi$ results obtained from the two\nexperimental methods are attributed to an inhomogeneous electric field\ndistribution. Extrapolation yields an effective width of dominant potential\ndrop of about $100 mu$m. On the other hand, our analysis suggests a divergence\nof the dielectric function $\\epsilon_{r} \\propto \\xi^{\\beta}$ with $\\beta\n\\simeq 1$."
    },
    {
        "anchor": "Remanence effects in the electrical resistivity of spin glasses: We have measured the low temperature electrical resistivity of Ag : Mn\nmesoscopic spin glasses prepared by ion implantation with a concentration of\n700 ppm. As expected, we observe a clear maximum in the resistivity (T ) at a\ntemperature in good agreement with theoretical predictions. Moreover, we\nobserve remanence effects at very weak magnetic fields for the resistivity\nbelow the freezing temperature Tsg: upon Field Cooling (fc), we observe clear\ndeviations of (T ) as compared with the Zero Field Cooling (zfc); such\ndeviations appear even for very small magnetic fields, typically in the Gauss\nrange. This onset of remanence for very weak magnetic fields is reminiscent of\nthe typical signature on magnetic susceptibility measurements of the spin glass\ntransition for this generic glassy system.",
        "positive": "Spin mediated magneto-electro-thermal transport behavior in\n  Ni80Fe20/MgO/p-Si thin films: In Si, spin-phonon interaction is the primary spin relaxation mechanism. At\nlow temperatures, the absence of spin-phonon relaxation will lead to enhanced\nspin accumulation. Spin accumulation may change the electro-thermal transport\nwithin the material, and thus may serve as an investigative tool for\ncharacterizing spin-mediated behavior. Here we present the first experimental\nproof of spin accumulation induced electro-thermal transport behavior in a Pd\n(1 nm)/Ni80Fe20 (25 nm)/MgO (1 nm)/p-Si (2 um) specimen. The spin accumulation\noriginates from the spin-Hall effect. The spin accumulation changes the\nphononic thermal transport in p-Si causing the observed magneto-electro-thermal\ntransport behavior. We also observe the inverted switching behavior in\nmagnetoresistance measurement at low temperatures in contrast to magnetic\ncharacterization, which is attributed to the canted spin states in p-Si due to\nspin accumulation. The spin accumulation is elucidated by current dependent\nanomalous Hall resistance measurement, which shows a decrease as the electric\ncurrent is increased. This result may open a new paradigm in the field of\nspin-mediated transport behavior in semiconductor and semiconductor\nspintronics."
    },
    {
        "anchor": "Evidence for flat zero-energy bands in bilayer graphene with a periodic\n  defect lattice: In this work, we perform ab initio calculations, based on the density\nfunctional theory, of the effects on the graphene bilayer when we intercalate\ncarbon atoms between the layers. We use the unit cell of the bilayer to\nconstruct larger unit cells (supercells), positioning a single carbon atom in\nthe hollow position between the monolayers and periodically replicating the\nsupercell. By increasing the size of the unit cell and consequently, the\nperiodicity of the inserted atoms, we are able to minimize the carbon-carbon\ninteraction and therefore infer the changes in the electronic, vibrational and\nthermal behavior of the bilayer when the intercalated atoms do not interact\nwith each other. The main result, concerning the electronic properties, is the\nappearance of a doubly degenerate flat band at the Fermi level. These states\nare interpreted as coming from the periodic deformation of the bilayer due to\nthe inserted atoms. It acts as a non-Abelian flux network creating zero energy\nat bands as predicted by San-Jose, Gonz\\'alez and Guinea in 2012. Since the\nperiodic strain field associated to the defect array has such a strong\ninfluence on the electronic properties of the bilayer, it may be useful for\npractical applications. For instance, it can act as frozen-in magnetic-like\nfield flux tubes. All-carbon nanostructures can then be designed to have\nelectronic behavior at different regions tailored by the chosen defect pattern.",
        "positive": "Soft X-ray phase nano-microscopy of micrometre-thick magnets: Imaging of nanoscale magnetic textures within extended material systems is of\ncritical importance both to fundamental research and technological\napplications. Whilst high resolution magnetic imaging of thin nanoscale samples\nis well-established with electron and soft X-ray microscopy, the extension to\nmicrometer-thick systems with hard X-rays currently limits high resolution\nimaging to rare-earth magnets. Here we overcome this limitation by establishing\nsoft X-ray magnetic imaging of micrometer-thick systems using the pre-edge\nphase X-ray Magnetic Circular Dichroism signal, thus making possible the study\nof a wide range of magnetic materials. By performing dichroic\nspectro-ptychography, we demonstrate high spatial resolution imaging of\nmagnetic samples up to 1.7 {\\mu}m thick, an order of magnitude higher than\nconventionally possible with absorption-based techniques. This new regime of\nmagnetic imaging makes possible the study of extended non rare-earth systems\nthat have until now been inaccessible, from magnetic textures for future\nspintronic applications to non-rare-earth permanent magnets."
    },
    {
        "anchor": "Interaction corrections to the minimal conductivity of graphene via\n  dimensional regularization: We compute the two-loop interaction correction to the minimal conductivity of\ndisorder-free intrinsic graphene with the help of dimensional regularization.\nThe calculation is done in two different ways: via density-density and via\ncurrent-current correlation functions. Upon properly renormalizing the\nperturbation theory, in both cases, we find that: $\\sigma = \\sigma_0\\,( 1 +\n\\al\\,(19-6\\pi)/12) \\approx \\sigma_0 \\,(1 + 0.01\\, \\al)$, where $\\al = e^2 / (4\n\\pi \\hbar v)$ is the renormalized fine structure constant and $\\sigma_0 = e^2 /\n(4 \\hbar)$. Our results are consistent with experimental uncertainties and\nresolve a theoretical dispute.",
        "positive": "Anomalous and Spin Hall Effects in a Magnetic Tunnel Junction with\n  Rashba Spin-Orbit Coupling: Anomalous and spin Hall effects are investigated theoretically for a magnetic\ntunnel junction where the applied voltage produces a Rashba spin-or bit\ncoupling within the tunneling barrier layer. The ferromagnetic electrodes are\nthe source of the spin-polarized current. The tunneling electrons experience a\nspin-orbit coupling inside the barrier due to the applied electrical field.\nCharge and spin Hall currents are calculated as functions of the position\ninside the barrier and the angle between the magnetizations of the electrodes.\nWe find that both charge and spin Hall currents are located inside the barrier\nnear the in terfaces. The dependence of the currents on magnetic configuration\nof the magnetic tunnel junction makes possible the manipulation by the Hall\ncurrents via rotation of the magnetization of the electrodes."
    },
    {
        "anchor": "Nodal Surfaces in Photoemission from Twisted Bilayer Graphene: Selection rules and interference effects in angle resolved photoemission\nspectra from twisted graphene bilayers are studied within a long wavelength\ntheory for the electronic structure. Using a generic model for the interlayer\ncoupling, we identify features in the calculated ARPES momentum distributions\nthat are controlled by the singularities and topological character of its long\nwavelength spectrum. We distinguish spectral features that are controlled by\nsingle-layer singularities in the spectrum, their modification by gauge\npotentials in each layer generated by the interlayer coupling, and new\nenergy-dependent interference effects that directly probe the interlayer\ncoherence. The results demonstrate how the energy- and polarization- dependence\nof ARPES spectra can be used to characterize the interlayer coupling in twisted\nbilayer graphenes.",
        "positive": "Pressure control of conducting channels in singlewall nanotube networks: We measure electrical transport on networks of single wall nanotube ropes as\na function of temperature T, voltage V and pressure up to 22GPa. We observe\nLuttinger liquid (LL) behavior, a conductance ~T^alpha and a dynamic\nconductance ~V^alpha. With pressure conductance increases while alpha\ndecreases, enabling us to test the theoretical prediction for LL on the alpha\ndependence of the T and V independent coefficient of the tunneling conductance,\nand to obtain the high frequency cut-off of LL modes. The possible transition\nto a fermi liquid at alpha -> 0 is unattainable, as nanotubes collapse to an\ninsulating state at high pressures."
    },
    {
        "anchor": "The optical signature of few-layer ReSe$_2$: Optical properties of thin layers of rhenium diselenide (ReSe$_2$) with\nthickness ranging from mono- (1 ML) to nona-layer (9 MLs) are demonstrated. The\nphotoluminescence (PL) and Raman scattering were measured at low ($T$=5 K) and\nroom ($T$=300 K) temperature, respectively. The PL spectra of ReSe$_2$ layers\ndisplay two well-resolved emission lines, which blueshift by about 120 meV when\nthe layer thickness decreases from 9 MLs to a monolayer. A rich structure of\nthe observed low-energy Raman scattering modes can be explained within a linear\nchain model. The two phonon modes of intralayer vibrations, observed in Raman\nscattering spectra at about 120 cm$^{-1}$, exhibit very sensitive and opposite\nevolution as a function of layer thickness. It is shown that their energy\ndifference can serve as a convenient and reliable tool to determine the\nthickness of ReSe$_2$ flakes in the few-layer limit.",
        "positive": "Observation of quantum-Hall effect in gated epitaxial graphene grown on\n  SiC (0001): Epitaxial graphene films were formed on the Si-face of semi-insulating 4H-SiC\nsubstrates by a high temperature sublimation process. A high-k gate stack on\nepitaxial graphene is realized by inserting a fully oxidized nanometer thin\naluminum film as a seeding layer followed by an atomic-layer deposition\nprocess. The electrical properties of epitaxial graphene films are sustained\nafter gate stack formation without significant degradation. At low\ntemperatures, the quantum-Hall effect in Hall resistance is observed along with\npronounced Shubnikov-de Hass oscillations in diagonal magneto-resistance of\ngated epitaxial graphene on SiC (0001)."
    },
    {
        "anchor": "Corner Junction as a Probe of Helical Edge States: We propose and analyze inter-edge tunneling in a quantum spin Hall corner\njunction as a means to probe the helical nature of the edge states. We show\nthat electron-electron interactions in the one-dimensional helical edge states\nresult in Luttinger parameters for spin and charge that are intertwined, and\nthus rather different than those for a quantum wire with spin rotation\ninvariance. Consequently, we find that the four-terminal conductance in a\ncorner junction has a distinctive form that could be used as evidence for the\nhelical nature of the edge states.",
        "positive": "Competition of Dzyaloshinskii-Moriya and higher-order exchange\n  interactions in Rh/Fe atomic bilayers on Ir(111): Using spin-polarized scanning tunneling microscopy and density functional\ntheory we demonstrate the occurrence of a novel type of noncollinear spin\nstructure in Rh/Fe atomic bilayers on Ir(111). We find that higher-order\nexchange interactions depend sensitively on the stacking sequence. For\nfcc-Rh/Fe/Ir(111) frustrated exchange interactions are dominant and lead to the\nformation of a spin spiral ground state with a period of about 1.5 nm. For\nhcp-Rh/Fe/Ir(111) higher-order exchange interactions favor a double-row wise\nantiferromagnetic or \"uudd\" state. However, the Dzyaloshinskii- Moriya\ninteraction at the Fe/Ir interface leads to a small angle of about 4{\\deg}\nbetween adjacent magnetic moments resulting in a canted \"uudd\" ground state."
    },
    {
        "anchor": "Tunable ferromagnetism at non-integer filling of a moir\u00e9 superlattice: The flat bands resulting from moir\\'e superlattices in magic-angle twisted\nbilayer graphene (MATBG) and ABC-trilayer graphene aligned with hexagonal boron\nnitride (ABC-TLG/hBN) have been shown to give rise to fascinating correlated\nelectron phenomena such as correlated insulators and superconductivity. More\nrecently, orbital magnetism associated with correlated Chern insulators was\nfound in this class of layered structures centered at integer multiples of n0,\nthe density corresponding to one electron per moir\\'e superlattice unit cell.\nHere we report the experimental observation of ferromagnetism at fractional\nfilling of a flat Chern band in an ABC-TLG/hBN moir\\'esuperlattice. The\nferromagnetic state exhibits prominent ferromagnetic hysteresis behavior with\nlarge anomalous Hall resistivity in a broad region of densities, centered in\nthe valence miniband at n = -2.3 n0. This ferromagnetism depends very\nsensitively on the control parameters in the moir\\'e system: not only the\nmagnitude of the anomalous Hall signal, but also the sign of the hysteretic\nferromagnetic response can be modulated by tuning the carrier density and\ndisplacement field. Our discovery of electrically tunable ferromagnetism in a\nmoir\\'e Chern band at non-integer filling highlights the opportunities for\nexploring new correlated ferromagnetic states in moir\\'e heterostructures.",
        "positive": "Ripplonic Lamb shift for electrons on liquid helium: We study the shift of the energy levels of electrons on helium surface due to\nthe coupling to the quantum field of surface vibrations. As in quantum\nelectrodynamics, the coupling is known, and it is known to lead to an\nultraviolet divergence of the level shifts. We show that there are diverging\nterms of different nature and use the Bethe-type approach to show that they\ncancel each other, to the leading-order. This resolves the long-standing\ntheoretical controversy and explains the existing experiments. The results\nallow us to study the temperature dependence of the level shift. The\npredictions are in good agreement with the experimental data."
    },
    {
        "anchor": "A real-time software simulator for scanning force microscopy: We describe software that simulates the hardware of a scanning force\nmicroscope. The essential feature of the software is its real-time response,\nwhich is critical for mimicking the behavior of real scanning probe hardware.\nThe simulator runs on an open-source real time Linux kernel, and can be used to\ntest scanning probe microscope control software as well as theoretical models\nof different types of scanning probe microscopes. We describe the\nimplementation of a tuning-fork based atomic force microscope and a dc\nelectrostatic force microscope, and present representative images obtained from\nthese models.",
        "positive": "Effect of electric current on optical orientation of electrons in\n  AlGaAs/GaAs heterostructure: The effect of a lateral electric current on the photoluminescence H-band of\nan AlGaAs/GaAs heterostructure is investigated. The photoluminescence intensity\nand optical orientation of electrons contributing to the H-band are studied by\nmeans of continuous wave and time-resolved photoluminescence spectroscopy and\ntime-resolved Kerr rotation. It is shown that the H-band is due to\nrecombination of the heavy holes localized at the heterointerface with\nphotoexcited electrons attracted to the heterointerface from the GaAs layer.\nTwo lines with significantly different decay times constitute the H-band: a\nshort-lived high-energy one and a long-lived low-energy one. The high-energy\nline originates from recombination of electrons freely moving along the\nstructure plane, while the low-energy one is due to recombination of\ndonor-bound electrons near the interface. Application of the lateral electric\nfield of ~ 100-200 V/cm results in a quenching of both lines. This quenching is\ndue to a decrease of electron concentration near the heterointerface as a\nresult of a photocurrent-induced heating of electrons in the GaAs layer. On the\ncontrary, electrons near the heterointerface are effectively cooled, so the\ndonors near the interface are not completely empty up to ~ 100 V/cm, which is\nin stark contrast with the case of bulk materials. The optical spin\npolarization of the donor-bound electrons near the heterointerface weakly\ndepends on the electric field. Their polarization kinetics is determined by the\nspin dephasing in the hyperfine fields of the lattice nuclei. The long spin\nmemory time (> 40 ns) can be associated with suppression of the\nBir-Aronov-Pikus mechanism of spin relaxation for electrons."
    },
    {
        "anchor": "Spin Precession and Oscillations in Mesoscopic Systems: We compare and contrast magneto-transport oscillations in the fully quantum\n(single-electron coherent) and classical limits for a simple but illustrative\nmodel. In particular, we study the induced magnetization and spin current in a\ntwo-terminal double-barrier structure with an applied Zeeman field between the\nbarriers and spin disequilibrium in the contacts. Classically, the spin current\nshows strong tunneling resonances due to spin precession in the region between\nthe two barriers. However, these oscillations are distinguishable from those in\nthe fully coherent case, for which a proper treatment of the electron phase is\nrequired. We explain the differences in terms of the presence or absence of\ncoherent multiple wave reflections.",
        "positive": "Quantum Hall effect on centimeter scale chemical vapor deposited\n  graphene films: We report observations of well developed half integer quantum Hall effect\n(QHE) on mono layer graphene films of 7 mm \\times 7 mm in size. The graphene\nfilms are grown by chemical vapor deposition (CVD) on copper, then transferred\nto SiO_{2} /Si substrates, with typical carrier mobilities \\approx 4000 cm^{2}\n/Vs. The large size graphene with excellent quality and electronic homogeneity\ndemonstrated in this work is promising for graphene-based quantum Hall\nresistance standards, and can also facilitate a wide range of experiments on\nquantum Hall physics of graphene and practical applications exploiting the\nexceptional properties of graphene."
    },
    {
        "anchor": "The Computational 2D Materials Database: High-Throughput Modeling and\n  Discovery of Atomically Thin Crystals: We introduce the Computational 2D Materials Database (C2DB), which organises\na variety of structural, thermodynamic, elastic, electronic, magnetic, and\noptical properties of around 1500 two-dimensional materials distributed over\nmore than 30 different crystal structures. Material properties are\nsystematically calculated by state-of-the art density functional theory and\nmany-body perturbation theory (G$_0\\!$W$\\!_0$ and the Bethe-Salpeter Equation\nfor $\\sim$200 materials) following a semi-automated workflow for maximal\nconsistency and transparency. The C2DB is fully open and can be browsed online\nor downloaded in its entirety. In this paper, we describe the workflow behind\nthe database, present an overview of the properties and materials currently\navailable, and explore trends and correlations in the data. Moreover, we\nidentify a large number of new potentially synthesisable 2D materials with\ninteresting properties targeting applications within spintronics,\n(opto-)electronics, and plasmonics. The C2DB offers a comprehensive and easily\naccessible overview of the rapidly expanding family of 2D materials and forms\nan ideal platform for computational modeling and design of new 2D materials and\nvan der Waals heterostructures.",
        "positive": "Radiative Decay of Dark Exciton Related Emission in a Sandwiched\n  Monolayer WSe2 Revealed by Room Temperature Micro and Nano Photoluminescence: TMDCs have attracted a lot of attention in recent years due to their unique\nindirect to direct band gap transition from bulk to monolayer thickness. Strong\nconfinement in the out-of-plane direction enhances the Coulomb potential\nbetween the charged particles (e-h pairs) and thus increases the exciton\nbinding energy dramatically. The lattice inversion asymmetry in a monolayer\ncreates two non-equivalent (but degenerate in energy) band edges protected by\ntime reversal polarisation via pseudo-spin. However, the presence of strong\nspin-orbit coupling in the valence band and weak spin-splitting in the\nconduction band results in the lowest lying exciton in WX2 (X = S, Se) being\nspin forbidden and optically dark. Because of their long life times, dark\nexcitons (XD) are highly attractive for quantum optics and optoelectronic\napplications. To date studying XD emission is limited to cryogenic temperature\nor required very complex experimental configurations to observe them at room\ntemperature (RT). Here, we demonstrate a novel approach of radiative decay of\nXD related emissions in 1L-WSe2 studied by micro and nano PL at RT. 1L-WSe2\nflakes were sandwiched by noble metal (Au or Ag) substrates and PDMS\nnano-patches providing a strong local out-of-plane dipole moment with respect\nto the 2D plane. This strong dipole moment not only enhances the XD in WSe2, it\nalso produces bound excitons due to extrinsic charge defects visible at RT. The\nspatial distributions of these XD related emissions were studied by TEPL with a\nspatial resolution < 10 nm confirming the confinement of these excitons within\nthe PDMS nano-patches. Finally, by removing the nano-patches from the top of\nthe flakes we are able to recover the bright excitons in the 1L-WSe2. Our\napproach paves the way for deep understanding and to harness excitonic\nproperties in low dimensional semiconductors, thus offering a platform towards\nquantum optics."
    },
    {
        "anchor": "Electron-photon correlations and the third moment of quantum noise: The radiation generated by a quantum conductor should be correlated with\nelectrons crossing it. We have measured the correlation between the\nfluctuations of the high frequency electromagnetic power and the low frequency\ntransport in a tunnel junction. We have explored the regimes where\nelectromagnetic fluctuations correspond to real photons and where they\ncorrespond to vacuum at very low temperature. We deduce from our data the\nintrinsic third moment of quantum shot noise, which appears to be frequency\nindependent.",
        "positive": "Comparison of charged-defect finite-size supercell correction methods in\n  a general framework: Starting from the total energy expressions within density functional theory,\nwe are able to perform a comparison of several currently used charged-defect\nfinite-size supercell correction schemes in a unified manner. This approach\nalso provides a framework for a further development of corrections not only for\nDFT supercell calculations, but also for more advanced methods and for complex\ngeometries. The comparison is performed for three separate defect cases: a\ngallium vacancy in GaAs, a beryllium interstitial in GaAs and a vacancy in\ndiamond. We found two methods working sufficiently well for all three cases: a\nmethod which is very similar to one presented by Freysoldt, and a slightly\naltered potential alignment method."
    },
    {
        "anchor": "Perpendicular magnetic anisotropy and magnetization process in CoFeB/Pd\n  multilayer films: Perpendicular magnetic anisotropy (PMA) and dynamic magnetization reversal\nprocess in [CoFeB $t$ nm/Pd 1.0 nm]$_n$ ($t$ = 0.4, 0.6, 0.8, 1.0, and 1.2 nm;\n$n$ = 2 - 20) multilayer films have been studied by means of magnetic\nhysteresis and Kerr effect measurements. Strong and controllable PMA with an\neffective uniaxial anisotropy up to 7.7$\\times$ 10$^6$ J.m$^{-3}$ and a\nsaturation magnetization as low as 200 emu/cc are achieved. Surface/interfacial\nanisotropy of CoFeB/Pd interfaces, the main contribution to the PMA, is\nseparated from the effective uniaxial anisotropy of the films, and appears to\nincrease with the number of the CoFeB/Pd bilayers. Observation of the magnetic\ndomains during a magnetization reversal process using polar magneto-optical\nKerr microscopy shows the detailed behavior of nucleation and displacement of\nthe domain walls.",
        "positive": "Reply to the reply to \"Comment on Universal out-of-equilibrium transport\n  in Kondo-correlated quantum dots\": I reply to the new arguments of Mu\\~noz et al. (arXiv:1308.0638) regarding\nour controversy on non-equilibrium Green functions of the impurity Anderson\nmodel, and to new unfounded criticism to my paper Ref. 1 (arXiv:1110.0816). In\nparticular, I show that the lesser self energy given in Ref. 1 does satisfy a\nWard identity. References are updated."
    },
    {
        "anchor": "Strong Nernst-Ettingshausen effect in folded graphene: We study electronic transport in graphene under the influence of a\ntransversal magnetic field $\\f{B}(\\f{r})=B(x)\\f{e}_z$ with the asymptotics\n$B(x\\to\\pm\\infty)=\\pm B_0$, which could be realized via a folded graphene sheet\nin a constant magnetic field, for example. By solving the effective Dirac\nequation, we find robust modes with a finite energy gap which propagate along\nthe fold -- where particles and holes move in opposite directions. Exciting\nthese particle-hole pairs with incident photons would then generate a nearly\nperfect charge separation and thus a strong magneto-thermoelectric\n(Nernst-Ettingshausen) or magneto-photoelectric effect -- even at room\ntemperature.",
        "positive": "Electronic states in a graphene flake strained by a Gaussian bump: The effect of strain in graphene is usually modeled by a pseudo-magnetic\nvector potential which is, however, derived in the limit of small strain. In\nrealistic cases deviations are expected in view of graphene's very high strain\ntolerance, which can be up to 25%. Here we investigate the pseudo-magnetic\nfield generated by a Gaussian bump and we show that it exhibits significant\ndifferences with numerical tight-binding results. Furthermore, we calculate the\nelectronic states in the strained region for a hexagon shaped flake with\narmchair edges. We find that the six-fold symmetry of the wave functions inside\nthe Gaussian bump is directly related to the different effect of strain along\nthe fundamental directions of graphene: zigzag and armchair. Low energy\nelectrons are strongly confined in the armchair directions and are localized on\nthe carbon atoms of a single sublattice."
    },
    {
        "anchor": "Weak values of electron spin in a double quantum dot: We propose a protocol for a controlled experiment to measure a weak value of\nthe electron's spin in a solid state device. The weak value is obtained by a\ntwo step procedure -- weak measurement followed by a strong one\n(post-selection), where the outcome of the first measurement is kept provided a\nsecond post-selected outcome occurs. The set-up consists of a double quantum\ndot and a weakly coupled quantum point contact to be used as a detector.\nAnomalously large values of the spin of a two electron system are predicted, as\nwell as negative values of the total spin. We also show how to incorporate the\nadverse effect of decoherence into this procedure.",
        "positive": "Stable Higher-Order Topological Dirac Semimetals with $\\mathbb{Z}_2$\n  Monopole Charge in Alternating-twisted Multilayer Graphenes and beyond: We demonstrate that a class of stable $\\mathbb{Z}_2$ monopole charge Dirac\npoint ($\\mathbb{Z}_2$DP) phases can robustly exist in real materials, which\nsurmounts the understanding: that is, a $\\mathbb{Z}_2$DP is unstable and\ngenerally considered to be only the critical point of a $\\mathbb{Z}_2$ nodal\nline ($\\mathbb{Z}_2$NL) characterized by a $\\mathbb{Z}_2$ monopole charge (the\nsecond Stiefel-Whitney number $w_2$) with space-time inversion symmetry but no\nspin-orbital coupling. For the first time, we explicitly reveal the\nhigher-order bulk-boundary correspondence in the stable $\\mathbb{Z}_2$DP phase.\nWe propose the alternating-twisted multilayer graphene, which can be regarded\nas 3D twisted bilayer graphene (TBG), as the first example to realize such\nstable $\\mathbb{Z}_2$DP phase and show that the Dirac points in the 3D TBG are\nessential degenerate at high symmetric points protected by crystal symmetries\nand carry a nontrivial $\\mathbb{Z}_2$ monopole charge ($w_2=1$), which results\nin higher-order hinge states along the entire Brillouin zone of the $k_z$\ndirection. By breaking some crystal symmetries or tailoring interlayer coupling\nwe are able to access $\\mathbb{Z}_2$NL phases or other $\\mathbb{Z}_2$DP phases\nwith hinge states of adjustable length. In addition, we present other 3D\nmaterials which host $\\mathbb{Z}_2$DPs in the electronic band structures and\nphonon spectra. We construct a minimal eight-band tight-binding lattice model\nthat captures these nontrivial topological characters and furthermore tabulate\nall possible space groups to allow the existence of the stable $\\mathbb{Z}_2$DP\nphases, which will provide direct and strong guidance for the realization of\nthe $\\mathbb{Z}_2$ monopole semimetal phases in electronic materials,\nmetamaterials and electrical circuits, etc."
    },
    {
        "anchor": "The key role of non-local screening in the environment-insensitive\n  exciton fine structures of transition-metal dichalcogenide monolayers: In this work, we present a comprehensive theoretical and computational\ninvestigation of exciton fine structures of WSe$_2$-monolayers, one of the best\nknown two-dimensional (2D) transition-metal dichalcogenides (TMD's), in various\ndielectric-layer environments by solving the first-principles-based\nBethe-Salpeter equation. While the physical and electronic properties of\natomically thin nano-materials are normally sensitive to the variation of\nsurrounding environment, our studies reveal that the influence of dielectric\nenvironment on the exciton fine structures of TMD-ML's is surprisingly limited.\nWe point out that the non-locality of Coulomb screening plays a key role to\nsuppress the factor of dielectric environment and drastically shrink the fine\nstructure splittings between bright exciton (BX) states and various dark\nexciton (DX) states of TMD-ML's. The intriguing non-locality of screening in 2D\nmaterials can be manifested by the measurable {\\it non-linear} correlation\nbetween the BX-DX splittings and exciton binding energies with varying the\nsurrounding dielectric environments. The revealed environment-insensitive\nexciton fine structures of TMD-ML's suggest the robustness of prospective\ndark-exciton-based opto-electronics against the inevitable variation of\ninhomogeneous dielectric environment.",
        "positive": "Towards room-temperature superfluidity of exciton polaritons in an\n  optical microcavity with an embedded MoS$_2$ monolayer: By considering driven diffusive dynamics of exciton polaritons in an optical\nmicrocavity with an embedded molybdenum disulfide monolayer, we determine\nexperimentally relevant range of parameters at which room-temperature\nsuperfuidity can be observed. It is shown that the superfluid transitions\noccurs in a trapped polariton gas at laser pumping power $P>600$ mW and and\ntrapping potential strength $k > 50$ eV/cm$^2$. We also propose a simple\nanalytic model that provides a useful estimate for the polariton gas density,\nwhich enables one to determine the conditions for observation of room\ntemperature polariton superfluidity."
    },
    {
        "anchor": "Discontinuous Euler instability in nanoelectromechanical systems: We investigate nanoelectromechanical systems near mechanical instabilities.\nWe show that quite generally, the interaction between the electronic and the\nvibronic degrees of freedom can be accounted for essentially exactly when the\ninstability is continuous. We apply our general framework to the Euler buckling\ninstability and find that the interaction between electronic and vibronic\ndegrees of freedom qualitatively affects the mechanical instability, turning it\ninto a discontinuous one in close analogy with tricritical points in the Landau\ntheory of phase transitions.",
        "positive": "Spin-textures, Berry's phase and Quasiparticle Interference in Bi2Te3: A\n  Topological Insulator with Warped Surface States: The energy-momentum relationship of electrons on the surface of an ideal\n\"Hydrogen-Atom\" Topological Insulator forms a cone - a Dirac cone, which, when\nwarped and distorted (no longer described by the Dirac equation), can lead to\nunusual phenomena such as enhanced electronic interference around defects\n(observed in STM) and a magnetically ordered broken symmetry surface with lost\ntopological protection. A detailed spin-texture and hexagonal warping maps on\nBi2Te3 are presented in this context as a Viewpoint on L.Fu, Phys. Rev. Lett.\n\\textbf{103}, 266801 (2009)."
    },
    {
        "anchor": "Evolution of Berry curvature and reentrant quantum anomalous Hall effect\n  in an intrinsic magnetic topological insulator: Recently, the magnetic topological insulator MnBi$_2$Te$_4$ emerged as a\ncompetitive platform to realize quantum anomalous Hall (QAH) states. We report\na Berry-curvature splitting mechanism to realize the QAH effect in the\ndisordered magnetic TI multilayers when switching from an antiferromagnetic\norder to a ferromagnetic order. We reveal that the splitting of spin-resolved\nBerry curvature, originating from the separation of the mobility edge during\nthe magnetic switching, can give rise to a QAH insulator even \\emph{without}\nclosing the band gap. We present a global phase diagram, and also provide a\nphenomenological picture to elucidate the Berry curvature splitting mechanism\nby the evolution of topological charges. At last, we predict that the Berry\ncurvature splitting mechanism will lead to a reentrant QAH effect, which can be\ndetected by tuning gate voltage. Our theory will be instructive for the studies\nof the QAH effect in MnBi$_2$Te$_4$ in future experiments.",
        "positive": "Anomalous transport model with axial magnetic fields: The transport properties of massless fermions in $3+1$ spacetime dimension\nhave been in the focus of recent theoretical and experimental research. New\ntransport properties appear as consequences of chiral anomalies. The most\nprominent is the generation of a current in a magnetic field, the so-called\nchiral magnetic effect leading to an enhancement of the electric conductivity\n(negative magnetoresistivity). We study the analogous effect for axial magnetic\nfields that couple with opposite signs to fermions of different chirality. We\nemphasize local charge conservation and study the induced\nmagneto-conductivities proportional to an electric field and a gradient in\ntemperature. We find that the magnetoconductivity is enhanced whereas the\nmagneto-thermoelectric conductivity is diminished. As a side result we\ninterpret an anomalous contribution to the entropy current as a generalized\nthermal Hall effect."
    },
    {
        "anchor": "Retrieval of material properties of monolayer transition-metal\n  dichalcogenides from magnetoexciton energy spectra: Reduced exciton mass, polarizability, and dielectric constant of the\nsurrounding medium are essential properties for semiconducting materials, and\nthey have been extracted recently from the magnetoexciton energies. However,\nthe acceptable accuracy of the suggested method requires very high magnetic\nintensity. Therefore, in the present paper, we propose an alternative method of\nextracting these material properties from recently available experimental\nmagnetoexciton s-state energies in monolayer transition-metal dichalcogenides\n(TMDCs). The method is based on the high sensitivity of exciton energies to the\nmaterial parameters in the Rytova-Keldysh model. It allows us to vary the\nconsidered material parameters to get the best fit of the theoretical\ncalculation to the experimental exciton energies for the $1s$, $2s$, and $3s$\nstates. This procedure gives values of the exciton reduced mass and $2D$\npolarizability. Then, the experimental magnetoexciton spectra compared to the\ntheoretical calculation also determine the average dielectric constant.\nConcrete applications are presented only for monolayers WSe$_2$ and WS$_2$ from\nthe recently available experimental data; however, the presented approach is\nuniversal and can be applied to other monolayer TMDCs. The mentioned fitting\nprocedure requires a fast and effective method of solving the Schr\\\"{o}dinger\nequation of an exciton in monolayer TMDCs with a magnetic field. Therefore, we\nalso develop such a method in this paper for highly accurate magnetoexciton\nenergies.",
        "positive": "High intensity study of THz detectors based on field effect transistors: Terahertz power dependence of the photoresponse of field effect transistors,\noperating at frequencies from 0.1 to 3 THz for incident radiation power density\nup to 100 kW/cm^2 was studied for Si metal-oxide-semiconductor field-effect\ntransistors and InGaAs high electron mobility transistors. The photoresponse\nincreased linearly with increasing radiation power up to kW/cm^2 range. The\nsaturation of the photoresponse was observed for all investigated field effect\ntransistors for intensities above several kW/cm^2. The observed signal\nsaturation is explained by drain photocurrent saturation similar to saturation\nin direct currents output characteristics. The theoretical model of terahertz\nfield effect transistor photoresponse at high intensity was developed. The\nmodel explains quantitatively experimental data both in linear and nonlinear\n(saturation) range. Our results show that dynamic range of field effect\ntransistors is very high and can extend over more than six orderd of magnitudes\nof power densities (from 0.5 mW/cm^2 to 5 kW/cm^2)."
    },
    {
        "anchor": "Fingerprints of classical diffusion in open 2D mesoscopic systems in the\n  metallic regime: We investigate the distribution of the resonance widths ${\\cal P}(\\Gamma)$\nand Wigner delay times ${\\cal P}(\\tau_W)$ for scattering from two-dimensional\nsystems in the diffusive regime. We obtain the forms of these distributions\n(log-normal for large $\\tau_W$ and small $\\Gamma$, and power law in the\nopposite case) for different symmetry classes and show that they are determined\nby the underlying diffusive classical dynamics. Our theoretical arguments are\nsupported by extensive numerical calculations.",
        "positive": "Numerical simulations of time resolved quantum electronics: This paper discusses the technical aspects - mathematical and numerical -\nassociated with the numerical simulations of a mesoscopic system in the time\ndomain (i.e. beyond the single frequency AC limit). After a short review of the\nstate of the art, we develop a theoretical framework for the calculation of\ntime resolved observables in a general multiterminal system subject to an\narbitrary time dependent perturbation (oscillating electrostatic gates, voltage\npulses, time-vaying magnetic fields) The approach is mathematically equivalent\nto (i) the time dependent scattering formalism, (ii) the time resolved Non\nEquilibrium Green Function (NEGF) formalism and (iii) the partition-free\napproach. The central object of our theory is a wave function that obeys a\nsimple Schrodinger equation with an additional source term that accounts for\nthe electrons injected from the electrodes. The time resolved observables\n(current, density. . .) and the (inelastic) scattering matrix are simply\nexpressed in term of this wave function. We use our approach to develop a\nnumerical technique for simulating time resolved quantum transport. We find\nthat the use of this wave function is advantageous for numerical simulations\nresulting in a speed up of many orders of magnitude with respect to the direct\nintegration of NEGF equations. Our technique allows one to simulate realistic\nsituations beyond simple models, a subject that was until now beyond the\nsimulation capabilities of available approaches."
    },
    {
        "anchor": "Persistent charge and spin currents in a 1D ring with Rashba and\n  Dresselhaus spin-orbit interactions by excitation with a terahertz pulse: Persistent, oscillatory charge and spin currents are shown to be driven by a\ntwo-component terahertz laser pulse in a one-dimensional mesoscopic ring with\nRashba-Dresselhaus spin orbit interactions (SOI) linear in the electron\nmomentum. The characteristic interference effects result from the opposite\nprecession directions imposed on the electron spin by the two SOI couplings.\nThe time dependence of the currents is obtained by solving numerically the\nequation of motion for the density operator, which is later employed in\ncalculating statistical averages of quantum operators on few electron\neigenstates. The parameterization of the problem is done in terms of the SOI\ncoupling constants and of the phase difference between the two laser\ncomponents. Our results indicate that the amplitude of the oscillations is\ncontrolled by the relative strength of the two SOI's, while their frequency is\ndetermined by the difference between the excitation energies of the electron\nstates. Furthermore, the oscillations of the spin current acquire a beating\npattern of higher frequency that we associate with the nutation of the electron\nspin between the quantization axes of the two SOI couplings. This phenomenon\ndisappears at equal SOI strengths, whereby the opposite precessions occur with\nthe same probability.",
        "positive": "Formation of Hydrogenated Graphene Nanoripples by Strain Engineering and\n  Directed Surface Self-assembly: We propose a new class of semiconducting graphene-based nanostructures:\nhydrogenated graphene nanoripples (HGNRs), based on continuum-mechanics\nanalysis and first principles calculations. They are formed via a two-step\ncombinatorial approach: first by strain engineered pattern formation of\ngraphene nanoripples, followed by a curvature-directed self-assembly of H\nadsorption. It offers a high level of control of the structure and morphology\nof the HGNRs, and hence their band gaps which share common features with\ngraphene nanoribbons. A cycle of H adsorption/desorption at/from the same\nsurface locations completes a reversible metal-semiconductor-metal transition\nwith the same band gap."
    },
    {
        "anchor": "Chemically-induced Mobility Gaps in Graphene Nanoribbons: A Route for\n  Upscaling Device Performances: We report a first-principles based study of mesoscopic quantum transport in\nchemically doped graphene nanoribbons with a width up to 10 nm. The occurrence\nof quasibound states related to boron impurities results in mobility gaps as\nlarge as 1 eV, driven by strong electron-hole asymmetrical backscattering\nphenomena. This phenomenon opens new ways to overcome current limitations of\ngraphene-based devices through the fabrication of chemically-doped graphene\nnanoribbons with sizes within the reach of conventional lithography.",
        "positive": "Exciton-polaron interactions in monolayer WS$_2$: Interactions between quasiparticles are of fundamental importance and\nultimately determine the macroscopic properties of quantum matter. A famous\nexample is the phenomenon of superconductivity, which arises from attractive\nelectron-electron interactions that are mediated by phonons or even other more\nexotic fluctuations in the material. Here we introduce mobile exciton\nimpurities into a two-dimensional electron gas and investigate the interactions\nbetween the resulting Fermi polaron quasiparticles. We employ multi-dimensional\ncoherent spectroscopy on monolayer WS$_2$, which provides an ideal platform for\ndetermining the nature of polaron-polaron interactions due to the underlying\ntrion fine structure and the valley specific optical selection rules. At low\nelectron doping densities, we find that the dominant interactions are between\npolaron states that are dressed by the same Fermi sea. In the absence of bound\npolaron pairs (bipolarons), we show using a minimal microscopic model that\nthese interactions originate from a phase-space filling effect, where excitons\ncompete for the same electrons. We furthermore reveal the existence of a\nbipolaron bound state with remarkably large binding energy, involving excitons\nin different valleys cooperatively bound to the same electron. Our work lays\nthe foundation for probing and understanding strong electron correlation\neffects in two-dimensional layered structures such as moir\\'e superlattices."
    },
    {
        "anchor": "AC Response of the Edge States in a Two-Dimensional Topological\n  Insulator Coupled to a Conducting Puddle: We calculate an AC response of the edge states of a two-dimensional\ntopological insulator, which can exchange electrons with a conducting puddle in\nthe bulk of the insulator. This exchange leads to finite corrections to the\nresponse of isolated edge states both at low and high frequencies. By comparing\nthese corrections, one may determine the parameters of the puddle.",
        "positive": "Imaging de Haas-van Alphen quantum oscillations and milli-Tesla\n  pseudomagnetic fields: A unique attribute of atomically thin quantum materials is the in-situ\ntunability of their electronic band structure by externally controllable\nparameters like electrostatic doping, electric field, strain, electron\ninteractions, and displacement or twisting of atomic layers. This unparalleled\ncontrol of the electronic bands has led to the discovery of a plethora of\nexotic emergent phenomena. But despite its key role, there is currently no\nversatile method for mapping the local band structure in advanced 2D materials\ndevices in which the active layer is commonly embedded in various insulating\nlayers and metallic gates. Utilizing a scanning superconducting quantum\ninterference device, we image the de Haas-van Alphen quantum oscillations in a\nmodel system, the Bernal-stacked trilayer graphene with dual gates, which\ndisplays multiple highly-tunable bands. By resolving thermodynamic quantum\noscillations spanning over 100 Landau levels in low magnetic fields, we\nreconstruct the band structure and its controllable evolution with the\ndisplacement field with unprecedented precision and spatial resolution of 150\nnm. Moreover, by developing Landau level interferometry, we reveal\nshear-strain-induced pseudomagnetic fields and map their spatial dependence. In\ncontrast to artificially-induced large strain, which leads to pseudomagnetic\nfields of hundreds of Tesla, we detect naturally occurring pseudomagnetic\nfields as low as 1 mT corresponding to graphene twisting by just 1 millidegree\nover one {\\mu}m distance, two orders of magnitude lower than the typical angle\ndisorder in high-quality twisted bilayer graphene devices. This ability to\nresolve the local band structure and strain on the nanoscale opens the door to\nthe characterization and utilization of tunable band engineering in practical\nvan der Waals devices."
    },
    {
        "anchor": "Slow Magnetic Relaxation of a 12-Metallacrown-4 Complex with a\n  Manganese(III)-Copper(II) Heterometallic Ring Motif: The heterobimetallic metallacrown (MC),\n(TMA)$_2${Mn(OAc)$_2$[12-MC$_{Mn(III)Cu(II)N(shi)}$-4](CH$_3$OH)}$\\cdot$2.90CH$_3$OH,\n1, where TMA$^+$ is tetramethylammonium, $^-$OAc is acetate, and shi$^{3-}$ is\nsalicylhydroximate, consists of a Mn$^{II}$ ion captured in the central cavity\nand alternating unambiguous and ordered manganese(III) and copper(II) sites\nabout the MC ring, a first for the archetypal MC structure design.\nDC-magnetometry characterization and subsequent simulation with the Spin\nHamiltonian $$H =\n-J_1(\\mathbf{s}_1+\\mathbf{s}_3)\\cdot\\mathbf{s}_5-J_2(\\mathbf{s}_2+\\mathbf{s}_4)\\cdot\\mathbf{s}_5-J_3\\sum_{i=1}^{4}\\mathbf{s}_i\\cdot\\mathbf{s}_{i+1}\n+ d(s_{z,1}^2 + s_{z,3}^2) + \\mu_B\\sum_{j=1}^5 g_j\\mathbf{s}_j\\cdot\\mathbf{B}$$\nindicates an S = 5/2 ground state and a sizable axial zero-field splitting on\nMn$^{III}$. AC-susceptibility measurements reveal that 1 displays slow\nmagnetization relaxation akin to single-molecule magnet (SMM) behavior.",
        "positive": "The Fano Effect in Aharonov-Bohm interferometers: After briefly reviewing the Fano effect, we explain why it may be relevant to\nvarious types of Aharonov-Bohm interferometers. We discuss both closed\n(electron conserving) and open interferometers, in which one path contains\neither a simple quantum dot or a decorated quantum dot (with more than one\ninternal state or a parallel path). The possible relevance to some hitherto\nunexplained experimental features is also discussed."
    },
    {
        "anchor": "Strongly enhanced nonlinear acoustic valley Hall effect in tilted Dirac\n  materials: It has been recently established that a nonlinear valley current could be\ngenerated through traveling a surface acoustic wave (SAW) in two-dimensional\nDirac materials. So far, the SAW-driven valley currents have been attributed to\nwarping Fermi surface or Berry phase effect. Here, we demonstrate that tilt\nmechanism can also lead to a nonlinear valley Hall current (VHC) when\npropagating SAW in materials with the tilted Dirac cone placed on a\npiezoelectric substrate. It's found that the nonlinear VHC exhibits a\n$\\sin\\theta$ dependence on the orientation of tilt with respect to SAW. In\naddition, this tilt-induced nonlinear acoustic VHC shows independence on the\nrelaxation time, distinguishing from the contributions from the Berry phase or\ntrigonal warping. Remarkably, the magnitude of the nonlinear acoustic VHC from\ntilt mechanism in the uniaxially strained graphene is two orders larger than\nthose reported in MoS$_2$ stemmed from the Berry phase effect and the warping\neffect.",
        "positive": "Phonons and electron-phonon coupling in graphene-h-BN heterostructures: First principle calculations of the phonons of graphene-BN heterostructures\nare presented and compared to those of the constituents. We show that AA and\nAB' stacking are not only energetically less favoured than AB but also\ndynamically unstable. We have identified low energy flat phonon branches of BN\ncharacter with out of plane displacement and evaluated their coupling to\nelectrons in graphene."
    },
    {
        "anchor": "High fidelity ac gate operations of the quantum dot hybrid qubit: Semiconductor quantum dots in silicon are promising qubits because of long\nspin coherence times and their potential for scalability. However, such qubits\nwith complete electrical control and fidelities above the threshold for quantum\nerror correction have not yet been achieved. We show theoretically that the\nthreshold fidelity can be achieved with ac gate operation of the quantum dot\nhybrid qubit. Formed by three electrons in a double dot, this qubit is\nelectrically controlled, does not require magnetic fields, and runs at GHz gate\nspeeds. We analyze the decoherence caused by 1/f charge noise in this qubit,\nfind the parameter regime for tunnel couplings and detuning that minimize the\ncharge noise dependence in the qubit frequency, and determine the optimal\nworking points for ac gate operations that drive the detuning and tunnel\ncoupling.",
        "positive": "Interacting Dirac Fermions on a Topological Insulator in a Magnetic\n  Field: We have studied the fractional quantum Hall states on the surface of a\ntopological insulator thin film in an external magnetic field, where the Dirac\nfermion nature of the charge carriers have been experimentally established only\nrecently. Our studies indicate that the fractional quantum Hall states should\nindeed be observable in the surface Landau levels of a topological insulator.\nThe strength of the effect will however be different, compared to that in\ngraphene, due to the finite thickness of the topological insulator film and due\nto the admixture of Landau levels of the two surfaces of the film. At a small\nfilm thickness, that mixture results in a strongly non-monotonic dependence of\nthe excitation gap on the film thickness. At a large enough thickness of the\nfilm, the excitation gap in the lowest two Landau levels are comparable in\nstrength."
    },
    {
        "anchor": "Nonlocality in microscale heat conduction: Thermal transport at short length and time scales inherently constitutes a\nnonlocal relation between heat flux and temperature gradient, but this is\nrarely addressed explicitly. Here, we present a formalism that enables detailed\ncharacterisation of the delocalisation effects in nondiffusive heat flow\nregimes. A convolution kernel $\\kappa^{\\ast}$, which we term the nonlocal\nthermal conductivity, fully embodies the spatiotemporal memory of the heat flux\nwith respect to the temperature gradient. Under the relaxation time\napproximation, the Boltzmann transport equation formally obeys the postulated\nconstitutive law and yields a generic expression for $\\kappa^{\\ast}$ in terms\nof the microscopic phonon properties. Subsequent synergy with stochastic\nframeworks captures the essential transport physics in compact models with easy\nto understand parameters. A fully analytical solution for $\\kappa^{\\ast}(x')$\nin tempered L\\'evy transport with fractal dimension $\\alpha$ and diffusive\nrecovery length $x_{\\text{R}}$ reveals that nonlocality is physically important\nover distances $\\sqrt{2-\\alpha} \\,\\,x_{\\text{R}}$. This is not only relevant to\nquasiballistic heat conduction in semiconductor alloys but also applies to\nsimilar dynamics observed in other disciplines including hydrology and\nchemistry. We also discuss how the previously introduced effective thermal\nconductivity $\\kappa_{\\text{eff}}$ inferred phenomenologically by transient\nthermal grating and time domain thermoreflectance measurements relates to\n$\\kappa^{\\ast}$. Whereas effective conductivities depend on the experimental\nconditions, the nonlocal thermal conductivity forms an intrinsic material\nproperty. Experimental results indicate nonlocality lengths of 400$\\,$nm in Si\nmembranes and $\\simeq 1\\,\\mu$m in InGaAs and SiGe, in good agreement with\ntypical median phonon mean free paths.",
        "positive": "Observation of second-harmonic generation induced by pure spin currents: Extensive efforts are currently being devoted to developing a new electronic\ntechnology, called spintronics, where the spin of electrons is explored to\ncarry information. [1,2] Several techniques have been developed to generate\npure spin currents in many materials and structures. [3-10] However, there is\nstill no method available that can be used to directly detect pure spin\ncurrents, which carry no net charge current and no net magnetization.\nCurrently, studies of pure spin currents rely on measuring the induced spin\naccumulation with optical techniques [5, 11-13] or spin-valve configurations.\n[14-17] However, the spin accumulation does not directly reflect the spatial\ndistribution or temporal dynamics of the pure spin current, and therefore\ncannot monitor the pure spin current in a real-time and real-space fashion.\nThis imposes severe constraints on research in this field. Here we demonstrate\na second-order nonlinear optical effect of the pure spin current. We show that\nsuch a nonlinear optical effect, which has never been explored before, can be\nused for the non-invasive, non-destructive, and real-time imaging of pure spin\ncurrents. Since this detection scheme does not rely on optical resonances, it\ncan be generally applied in a wide range of materials with different electronic\nbandstructures. Furthermore, the control of nonlinear optical properties of\nmaterials with pure spin currents may have potential applications in photonics\nintegrated with spintronics."
    },
    {
        "anchor": "Polarization jumps by breaking symmetries of two-dimensional Weyl\n  semimetals: The electric polarization as a bulk quantity is described by the modern\ntheory of polarization in insulating systems and cannot be defined in\nconducting systems. Upon a gradual change of a parameter in the system, the\npolarization always varies smoothly as long as the gap remains open. In this\npaper, we focus on the two-dimensional Weyl semimetal, which hosts Weyl nodes\nprotected by symmetries, and study the behavior of the polarization when a\nsymmetry-breaking term $M$ is introduced and a gap opens. We show that there\ncan be a jump between $M\\to0^+$ and $M\\to0^-$ limits. We find that the jump is\nuniversally described by the ``Weyl dipole\" representing how the Weyl nodes\nwith monopole charges are displaced in the reciprocal space. Our result is\napplicable to general two-dimensional Weyl semimetals.",
        "positive": "Contrast between spin and valley degrees of freedom: We measure the renormalized effective mass (m*) of interacting\ntwo-dimensional electrons confined to an AlAs quantum well while we control\ntheir distribution between two spin and two valley subbands. We observe a\nmarked contrast between the spin and valley degrees of freedom: When electrons\noccupy two spin subbands, m* strongly depends on the valley occupation, but not\nvice versa. Combining our m* data with the measured spin and valley\nsusceptibilities, we find that the renormalized effective Lande g-factor\nstrongly depends on valley occupation, but the renormalized conduction-band\ndeformation potential is nearly independent of the spin occupation."
    },
    {
        "anchor": "Photoluminescence of tetrahedral quantum-dot quantum wells: Taking into account the tetrahedral shape of a quantum dot quantum well\n(QDQW) when describing excitonic states, phonon modes and the exciton-phonon\ninteraction in the structure, we obtain within a non-adiabatic approach a\nquantitative interpretation of the photoluminescence spectrum of a single\nCdS/HgS/CdS QDQW. We find that the exciton ground state in a tetrahedral QDQW\nis bright, in contrast to the dark ground state for a spherical QDQW. The\nposition of the phonon peaks in the photoluminescence spectrum is attributed to\ninterface optical phonons. We also show that the experimental value of the\nHuang-Rhys parameter can be obtained only within the nonadiabatic theory of\nphonon-assisted transitions.",
        "positive": "Effects of Coulomb interactions on the splitting of luminescence lines: We study the splitting between the right-hand and left-hand circularly\npolarized luminescence lines in a quantum dot under relatively weak confinement\nregime and resonant high-power excitation. When the dot is populated with an\neven number of electron-hole pairs (biexciton and higher excitations), the\nsplitting measures basically the Zeeman energy. However, in the odd number of\npairs case, we have, in addition to the Zeeman and Overhauser shifts, a\ncontribution to the splitting coming from Coulomb interactions. This\ncontribution is of the order of a few meV, and shows distinct signatures of\nshell-filling in the quantum dot."
    },
    {
        "anchor": "Polarization sensitive photodectector based on GaAsN: We propose and numerically simulate an optoelectronic compact circular\npolarimeter. It allows to electrically measure the degree of circular\npolarization and light intensity at room temperature for a wide range of\nincidence angles in a single shot. The device, being based on GaAsN, is easy to\nintegrate into standard electronics and does not require bulky movable parts\nnor extra detectors. Its operation hinges mainly on two phenomena: the spin\ndependent capture of electrons and the hyperfine interaction between bound\nelectrons and nuclei on Ga$^{2+}$ paramagnetic centers in GaAsN. The first\nphenomenon confers the device with sensitivity to the degree of circular\npolarization and the latter allows to discriminate the handedness of the\nincident light.",
        "positive": "Controlled lasing from active optomechanical resonators: Planar microcavities with distributed Bragg reflectors (DBRs) host, besides\nconfined optical modes, also mechanical resonances due to stop bands in the\nphonon dispersion relation of the DBRs. These resonances have frequencies in\nthe sub-terahertz (10E10-10E11 Hz) range with quality factors exceeding 1000.\nThe interaction of photons and phonons in such optomechanical systems can be\ndrastically enhanced, opening a new route toward manipulation of light. Here we\nimplemented active semiconducting layers into the microcavity to obtain a\nvertical-cavity surface-emitting laser (VCSEL). Thereby three resonant\nexcitations -photons, phonons, and electrons- can interact strongly with each\nother providing control of the VCSEL laser emission: a picosecond strain pulse\ninjected into the VCSEL excites long-living mechanical resonances therein. As a\nresult, modulation of the lasing intensity at frequencies up to 40 GHz is\nobserved. From these findings prospective applications such as THz laser\ncontrol and stimulated phonon emission may emerge."
    },
    {
        "anchor": "Evidence of correlation in spin excitations of few-electron quantum dots: We report inelastic light scattering measurements of spin and charge\nexcitations in nanofabricated AlGaAs/GaAs quantum dots with few electrons. A\nnarrow spin excitation peak is observed and assigned to the intershell\ntriplet-to-singlet monopole mode of dots with four electrons.\nConfigurationinteraction theory provides precise quantitative interpretations\nthat uncover large correlation effects that are comparable to exchange Coulomb\ninteractions.",
        "positive": "Coulomb drag of viscous electron fluids: drag viscosity and negative\n  drag conductivity: We show that Coulomb drag in hydrodynamic bilayer systems leads to additional\nviscosity terms in the hydrodynamic equations, i.e., the drag and drag-Hall\nviscosities, besides the well-known kinematic and Hall viscosities. These new\nviscosity terms arise from a change of the stress tensor due to the interlayer\nCoulomb interactions. All four viscosity terms are tunable by varying the\napplied magnetic field and the electron densities in the two layers. At certain\nratios between the electron densities in the two layers, the drag viscosity\ndramatically changes the longitudinal transport resulting in a negative drag\nconductivity."
    },
    {
        "anchor": "Pseudo-zero-mode Landau levels and collective excitations in bilayer\n  graphene: Bilayer graphene in a magnetic field supports eight zero-energy Landau\nlevels, which, as a tunable band gap develops, split into two nearly-degenerate\nquartets separated by the band gap. A close look is made into the properties of\nsuch an isolated quartet of pseudo-zero-mode levels at half filling in the\npresence of an in-plane electric field and the Coulomb interaction, with focus\non revealing further controllable features in bilayer graphene. The half-filled\npseudo-zero-mode levels support, via orbital level mixing, charge carriers with\nnonzero electric moment, which would lead to field-induced level splitting and\nthe current-induced quantum Hall effect. It is shown that the Coulomb\ninteraction enhances the effect of the in-plane field and their interplay leads\nto rich spectra of collective excitations, pseudospin waves, accessible by\nmicrowave experiments; also a duality in the excitation spectra is revealed.",
        "positive": "The nature of localization in graphene under quantum Hall conditions: Particle localization is an essential ingredient in quantum Hall physics\n[1,2]. In conventional high mobility two-dimensional electron systems Coulomb\ninteractions were shown to compete with disorder and to play a central role in\nparticle localization [3]. Here we address the nature of localization in\ngraphene where the carrier mobility, quantifying the disorder, is two to four\norders of magnitude smaller [4,5,6,7,8,9,10]. We image the electronic density\nof states and the localized state spectrum of a graphene flake in the quantum\nHall regime with a scanning single electron transistor [11]. Our microscopic\napproach provides direct insight into the nature of localization. Surprisingly,\ndespite strong disorder, our findings indicate that localization in graphene is\nnot dominated by single particle physics, but rather by a competition between\nthe underlying disorder potential and the repulsive Coulomb interaction\nresponsible for screening."
    },
    {
        "anchor": "Stacking-Dependent Interlayer Phonons in 3R and 2H MoS$_{2}$: We have investigated the interlayer shear and breathing phonon modes in\nMoS$_{2}$ with pure 3R and 2H stacking order by using polarization-dependent\nultralow-frequency Raman spectroscopy. We observe up to three shear branches\nand four breathing branches in MoS$_{2}$ with thickness from 2 to 13 layers.\nThe breathing modes show the same Raman activity behavior for both polytypes,\nbut the 2H breathing frequencies are consistently several wavenumbers higher\nthan the 3R breathing frequencies, signifying that 2H MoS$_{2}$ has slightly\nstronger interlayer lattice coupling than 3R MoS$_{2}$. In contrast, the\nshear-mode Raman spectra are strikingly different for 2H and 3R MoS$_{2}$.\nWhile the strongest shear mode corresponds to the highest-frequency branch in\nthe 2H structure, it corresponds to the lowest-frequency branch in the 3R\nstructure. Such distinct and complementary Raman spectra of the 3R and 2H\npolytypes allow us to survey a broad range of shear modes in MoS$_{2}$, from\nthe highest to lowest branch. By combining the linear chain model, group\ntheory, effective bond polarizability model and first-principles calculations,\nwe can account for all the major observations in our experiment.",
        "positive": "Dipole-exchange spin waves in Fibonacci magnetic multilayers: A microscopic model is employed to calculate the spectrum of spin waves in\nquasiperiodic magnetic multilayers in the dipole-exchange regime. Results are\npresented for structures in which thin ferromagnetic films are separated by\nnon-magnetic spacers following a Fibonacci sequence and extend previous\nmagnetostatic calculations. The results show the splitting of the frequency\nbands and the mode mixing caused by the dipolar interaction between the films\nas a function of spacer thickness, as well as the fractal aspect of the\nspectrum induced by the non-periodic aspect of the structure."
    },
    {
        "anchor": "Quantum interference from sums over closed paths for electrons on a\n  three-dimensional lattice in a magnetic field: total energy, magnetic moment,\n  and orbital susceptibility: We study quantum interference effects due to electron motion on a\nthree-dimensional cubic lattice in a continuously-tunable magnetic field of\narbitrary orientation and magnitude. These effects arise from the interference\nbetween magnetic phase factors associated with different electron closed paths.\nThe sums of these phase factors, called lattice path-integrals, are\n``many-loop\" generalizations of the standard ``one-loop\" Aharonov-Bohm-type\nargument. Our lattice path integral calculation enables us to obtain various\nimportant physical quantities through several different methods. The spirit of\nour approach follows Feynman's programme: to derive physical quantities in\nterms of ``sums over paths\". From these lattice path-integrals we compute\nanalytically, for several lengths of the electron path, the half-filled\nFermi-sea ground-state energy of noninteracting spinless electrons in a cubic\nlattice. Our results are valid for any strength of the applied magnetic field\nin any direction. We also study in detail two experimentally important\nquantities: the magnetic moment and orbital susceptibility at half-filling, as\nwell as the zero-field susceptibility as a function of the Fermi energy.",
        "positive": "Magnetic Susceptibility of Dirac Fermions, Bi-Sb Alloys, Interacting\n  Bloch Fermions, Dilute Nonmagnetic Alloys, and Kondo Alloys: Wide ranging interest in Dirac Hamiltomian is due to the emergence of novel\nmaterials, namely, graphene, topological insulators and superconductors, the\nnewly-discovered Weyl semimetals, and still actively-sought after Majorana\nfermions in real materials. We give a brief review of the relativistic Dirac\nquantum mechanics and its impact in the developments of modern physics. The\nquantum band dynamics of Dirac Hamiltonian is crucial in resolving the giant\ndiamagnetism of bismuth and Bi-Sb alloys. Quantitative agreement of the theory\nwith the experiments on Bi-Sb alloys has been achieved, and physically\nmeaningful contributions to the diamagnetism has been identified. We also treat\nrelativistic Dirac fermion as an interband dynamics in uniform magnetic fields.\nFor the interacting Bloch electrons, the role of translation symmetry for\ncalculating the magnetic susceptibility avoids any approximation to second\norder in the field. The magnetic susceptibility of Hubbard model and those of\nFermi liquids are readily obtained as limiting cases. The expressions for\nmagnetic susceptibility of dilute nonmagnetic alloys give a firm theoretical\nfoundation of the empirical formulas used in fitting experimental results. For\ncompleteness, the magnetic susceptibility of dilute magnetic or Kondo alloys is\nalso given for high and low temperature regimes."
    },
    {
        "anchor": "Asymmetry of the Geometrical Resonances of Composite Fermions: We propose an experiment to test the uniform-Berry-curvature picture of\ncomposite fermions. We show that the asymmetry of geometrical resonances\nobserved in a periodically modulated composite fermion system can be explained\nwith the uniform-Berry-curvature picture. Moreover, we show that an alternative\nway of modulating the system, i.e., modulating the external magnetic field,\nwill induce an asymmetry opposite to that of the usual periodic grating\nmodulation which effectively modulates the Chern-Simons field. The experiment\ncan serve as a critical test of the uniform-Berry-curvature picture, and probe\nthe dipole structure of composite fermions proposed by Read.",
        "positive": "Visualising Majorana bound states in 1D and 2D using the generalized\n  Majorana polarization: We study the solutions of generic Hamiltonians exhibiting particle-hole\nmixing. We show that there exists a universal quantity that can describe\nlocally the Majorana nature of a given state. This pseudo-spin like\ntwo-component quantity is in fact a generalization of the Majorana polarization\n(MP) measure introduced in Sticlet et al. 2012, which was applicable only for\nsome models with specific spin and symmetry properties. We apply this to an\nopen two-dimensional Kitaev system, as well as to a one-dimensional topological\nwire. We show that the MP characterization is a necessary and sufficient\ncriterion to test whether a state is a Majorana or not, and use it to\nnumerically determine the topological phase diagram."
    },
    {
        "anchor": "UV Photosensing Characteristics of Nanowire-Based GaN/AlN Superlattices: We have characterized the photodetection capabilities of single GaN nanowires\nincorporating 20 periods of AlN/GaN:Ge axial heterostructures enveloped in an\nAlN shell. Transmission electron microscopy confirms the absence of an\nadditional GaN shell around the heterostructures. In the absence of a surface\nconduction channel, the incorporation of the heterostructure leads to a\ndecrease of the dark current and an increase of the photosensitivity. A\nsignificant dispersion in the magnitude of dark currents for different single\nnanowires is attributed to the coalescence of nanowires with displaced\nnanodisks, reducing the effective length of the heterostructure. A larger\nnumber of active nanodisks and AlN barriers in the current path results in\nlower dark current and higher photosensitivity, and improves the sensitivity of\nthe nanowire to variations in the illumination intensity (improved linearity).\nAdditionally, we observe a persistence of the photocurrent, which is attributed\nto a change of the resistance of the overall structure, particularly the GaN\nstem and cap sections. In consequence, the time response is rather independent\nof the dark current.",
        "positive": "Unlocking Hidden Spins in Centrosymmetric SnSe2 by Vacancy-Controlled\n  Spin-Orbit Scattering: Spin current generation and manipulation remain the key challenge of\nspintronics, in which relativistic spinorbit coupling (SOC) play a ubiquitous\nrole. In this letter, we demonstrate that hidden Rashba spins in the\nnon-magnetic, centrosymmetric lattice of multilayer SnSe2 can be efficiently\nactivated by spin-orbit scattering introduced by Se vacancies. Via vacancy\nscattering, conduction electrons with hidden spin-momentum locked polarizations\nacquire out-of-plane magnetization components, which effectively break the\nchiral symmetry between the two Se sublattices of an SnSe2 monolayer when\nelectron spins start precession in the strong built-in Rashba SOC field. The\nresulting spin separations are manifested in quantum transport as vacancy\nconcentrationand temperature-dependent crossovers from weak antilocalization\n(WAL) to weak localization (WL), with the distinctive spin relaxation mechanism\nof the Dyakonov-Perel type. Our study shows the great potential of\ntwodimensional systems with hidden-spin textures for spintronics."
    },
    {
        "anchor": "Vibrational coherence in electron spin resonance in nanoscale\n  oscillators: We study a scheme for electrical detection, using electron spin resonance, of\ncoherent vibrations in a molecular single electron level trapped near a\nconduction channel. Both equilibrium spin-currents and non-equilibrium spin-\nand charge currents are investigated. Inelastic side-band anti-resonances\ncorresponding to the vibrational modes appear in the electron spin resonance\nspectrum.",
        "positive": "Improved Contacts to MoS2 Transistors by Ultra-High Vacuum Metal\n  Deposition: The scaling of transistors to sub-10 nm dimensions is strongly limited by\ntheir contact resistance (Rc). Here we present a systematic study of scaling\nMoS2 devices and contacts with varying electrode metals and controlled\ndeposition conditions, over a wide range of temperatures (80 to 500 K), carrier\ndensities (10^12 to 10^13 1/cm^2), and contact dimensions (20 to 500 nm). We\nuncover that Au deposited in ultra-high vacuum (~10^-9 Torr) yields three times\nlower Rc than under normal conditions, reaching 740 Ohm-um and specific contact\nresistivity 3x10^-7 Ohm.cm2, stable for over four months. Modeling reveals\nseparate Rc contributions from the Schottky barrier and the series access\nresistance, providing key insights on how to further improve scaling of MoS2\ncontacts and transistor dimensions. The contact transfer length is ~35 nm at\n300 K, which is verified experimentally using devices with 20 nm contacts and\n70 nm contact pitch (CP), equivalent to the \"14 nm\" technology node."
    },
    {
        "anchor": "The competition between superconductivity and ferromagnetism in small\n  metallic grains: thermodynamic properties: We study the thermodynamic properties of a small superconducting metallic\ngrain using a quantum Monte Carlo method. The grain is described by the\nuniversal Hamiltonian, containing pairing and ferromagnetic exchange\ncorrelations. In particular, we study how the thermodynamic signatures of\npairing correlations are affected by the spin exchange interaction. We find the\nexchange interaction effects to be qualitatively different in the BCS and\nfluctuation-dominated regimes of pairing correlations.",
        "positive": "Doubled Moir\u00e9 Flat Bands in Double-twisted Few Layer Graphite: We study the electronic structure of a double-twisted few layer graphite\n(DTFLG), which consists of three few layer graphite (FLG), i.e. ABA-stacked\ngraphene multilayer, stacked with two twist angles. We consider two categories\nof DTFLG, alternately twisted case and chirally twisted one, according to the\nrotation direction of the two twist angles. We show that, once the middle FLG\nof DTFLG is not thinner than trilayer, both kinds of DTFLG can remarkably host\ntwo pairs of degenerate moir\\'{e} flat bands (MFBs) at $E_f$, twice that of the\nmagic angle twisted bilayer graphene (TBG). The doubled MFBs of DTFLG lead to\ndoubled DOS at $E_f$, which implies much stronger correlation effects than the\nTBG. The degeneracy of MFBs can be lifted by a perpendicular electric field,\nand the isolated MFBs have nonzero valley Chern number. We also reveal the\npeculiar wave function patterns of the MFBs in the DTFLG. Our results establish\na new family of moir\\'{e} systems that have the much larger DOS at $E_f$, and\nthus possible much stronger correlation effects."
    },
    {
        "anchor": "Determination of the bandgap and split-off band of wurtzite GaAs: GaAs nanowires with a 100% wurtzite structure are synthesized by the\nvapor-liquid-solid method in a molecular beam epitaxy system, using gold as a\ncatalyst. We use resonant Raman spectroscopy and photoluminescence to determine\nthe position of the crystal-field split-off band of hexagonal wurtzite GaAs.\nThe temperature dependence of this transition enables us to extract the value\nat 0 K, which is 1.982 eV. Our photoluminescence excitation spectroscopy\nmeasurements are consistent with a band gap of GaAs wurtzite below 1.523 eV.",
        "positive": "Inhomogeneous Gilbert damping from impurities and electron-electron\n  interactions: We present a unified theory of magnetic damping in itinerant electron\nferromagnets at order $q^2$ including electron-electron interactions and\ndisorder scattering. We show that the Gilbert damping coefficient can be\nexpressed in terms of the spin conductivity, leading to a Matthiessen-type\nformula in which disorder and interaction contributions are additive. In a weak\nferromagnet regime, electron-electron interactions lead to a strong enhancement\nof the Gilbert damping."
    },
    {
        "anchor": "Nano antenna-assisted quantum dots emission into high-index planar\n  waveguide: Integrated quantum photonic circuits require the efficient coupling of photon\nsources to photonic waveguides. Hybrid plasmonic/photonic platforms are a\npromising approach, taking advantage of both plasmon modal confinement for\nefficient coupling to a nearby emitter and photonic circuitry for optical data\ntransfer and processing. In this work, we established directional quantum dot\n(QD) emission coupling to a planar TiO$_2$ waveguide assisted by a Yagi-Uda\nantenna. Antenna on waveguide is first designed by scaling radio frequency\ndimensions to nano-optics, taking into account the hybrid plasmonic/photonic\nplatform. Design is then optimized by full numerical simulations. We fabricate\nthe antenna on a TiO$_2$ planar waveguide and deposit a few QDs close to the\nYagi-Uda antenna. The optical characterization shows clear directional coupling\noriginating from antenna effect. We estimate the coupling efficiency and\ndirectivity of the light emitted into the waveguide.",
        "positive": "Confinement enhanced viscosity vs shear thinning in lubricated ice\n  friction: The ice surface is known for presenting a very small kinetic friction\ncoefficient, but the origin of this property remains highly controversial to\ndate. In this work, we revisit recent computer simulations of ice sliding on\natomically smooth substrates, using newly calculated bulk viscosities for the\nTIP4P/Ice water model. The results show that spontaneously formed premelting\nfilms in static conditions exhibit an effective viscosity which is about twice\nthe bulk viscosity. However, upon approaching sliding speeds in the order of\nm/s, the shear rate becomes very large, and the viscosities decrease by several\norders of magnitude. This shows that premelting films can act as an efficient\nlubrication layer despite their small thickness, and illustrates an interesting\ninterplay between confinement enhanced viscosities, and shear thinning. Our\nresults suggest that the strongly thinned viscosities that operate under the\nhigh speed skating regime could largely reduce the amount of frictional\nheating."
    },
    {
        "anchor": "Amplification and squeezing of quantum noise with a tunable Josephson\n  metamaterial: It has recently become possible to encode the quantum state of\nsuperconducting qubits and the position of nanomechanical oscillators into the\nstates of microwave fields. However, to make an ideal measurement of the state\nof a qubit, or to detect the position of a mechanical oscillator with\nquantum-limited sensitivity requires an amplifier that adds no noise. If an\namplifier adds less than half a quantum of noise, it can also squeeze the\nquantum noise of the electromagnetic vacuum. Highly squeezed states of the\nvacuum serve as an important quantum information resource. They can be used to\ngenerate entanglement or to realize back-action-evading measurements of\nposition. Here we introduce a general purpose parametric device, which operates\nin a frequency band between 4 and 8 GHz. It is a subquantum-limited microwave\namplifier, it amplifies quantum noise above the added noise of commercial\namplifiers, and it squeezes quantum fluctuations by 10 dB.",
        "positive": "A Tunable Kondo Effect in Quantum Dots: We demonstrate a tunable Kondo effect realized in small quantum dots. We can\nswitch our dot from a Kondo impurity to a non-Kondo system as the number of\nelectrons on the dot is changed from odd to even. We show that the Kondo\ntemperature can be tuned by means of a gate voltage as a single-particle energy\nstate nears the Fermi energy. Measurements of the temperature and magnetic\nfield dependence of a Coulomb-blockaded dot show good agreement with\npredictions of both equilibrium and non-equilibrium Kondo effects."
    },
    {
        "anchor": "Nonequilibrium Transport through Double Quantum Dots: Exact Results near\n  Quantum Critical Point: We study a double quantum dot in the regime where each dot carries a\nspin-1/2. This system is described by the 2-impurity Kondo model, having a\nnon-Fermi liquid fixed point for a critical value of the inter-impurity\ncoupling. The Hamiltonian describing the vicinity of the critical point,\nincluding the relevant potential scattering perturbations, can be cast in\nquadratic form. This allows us to predict a universal scaling function for the\nfinite temperature nonlinear conductance along the crossover from the critical\npoint to the surrounding stable fixed points.",
        "positive": "Conductance of a molecular wire attached to mesoscopic leads: contact\n  effects: We study linear electron transport through a molecular wire sandwiched\nbetween nanotube leads. We show that the presence of such electrodes strongly\ninfluences the calculated conductance. We find that depending on the quality\nand geometry of the contacts between the molecule and the tubular reservoirs,\nlinear transport can be tuned between an effective Newns spectral behavior and\na more structured one. The latter strongly depends on the topology of the\nleads. We also provide analytical evidence for an anomalous behavior of the\nconductance as a function of the contact strength."
    },
    {
        "anchor": "A nearly closed ballistic billiard with random boundary transmission: A variety of mesoscopic systems can be represented as a billiard with a\nrandom coupling to the exterior at the boundary. Examples include quantum dots\nwith multiple leads, quantum corrals with different kinds of atoms forming the\nboundary, and optical cavities with random surface refractive index. The\nspecific example we study is a circular (integrable) billiard with no internal\nimpurities weakly coupled to the exterior by a large number of leads with one\nchannel open in each lead. We construct a supersymmetric nonlinear\n$\\sigma$-model by averaging over the random coupling strengths between bound\nstates and channels. The resulting theory can be used to evaluate the\nstatistical properties of any physically measurable quantity in a billiard. As\nan illustration, we present results for the local density of states.",
        "positive": "Partial condensation of mobile excitons in graphene multilayers: At a large displacement field, in rhomboedral and Bernal-stacked graphene a\nnormal paramagnetic state transitions to a correlated state. Recent experiments\nshowed that such systems have several phase transitions as a function of the\ncarrier density. The phase adjacent to a paramagnetic state has anomalously\nhigh resistance and reduced degeneracy of the Fermi sea. We show that both\nphenomena can be explained through a concept of partial intervalley exciton\ncondensation: a fraction of particles condenses into excitons, and another\nforms an intervalley coherent Fermi liquid. The exciton part of the system do\nnot contribute to the electrical current thus increasing the resistance. Within\nthis paradigm, the increase in the resistance has entirely geometrical origin.\nWe check validity of the phenomenological theory through numerical\ncalculations. We also show that the quantum oscillation data should not be very\ndifferent between the partial excitonic state and the intervalley coherent\nstates suggested by other authors. Further, we suggest STM/AFM or Raman\nspectroscopy to have a conclusive evidence for the occurrence of the partial\nexciton condensation that we suggest in this paper."
    },
    {
        "anchor": "Spin-dependent thermoelectric phenomena in a quantum dot attached to\n  ferromagnetic and superconducting electrodes: We investigate transport and thermoelectric properties of hybrid systems\nbased on a single-level quantum dot and one superconducting lead. The other\nlead is generally normal-metallic ferromagnet. In the latter case\nsingle-particle transport is spin-polarized. Our main interest is in the\ninterplay of Andreev tunneling of Cooper pairs and single-particle tunneling.\nThe latter is responsible for relatively large thermopower and figure of merit\ndue to a diverging density of single-particle states at the superconducting gap\nedges. System with ferromagnetic and superconducting leads can also reveal spin\nthermoelectric phenomena. Finite superconducting gap is considered within the\nBCS theory, and the thermoelectric coefficients are calculated by means of\nnonequilibrium Green's function technique within Hartree-Fock like\napproximation with respect to the intradot Coulomb interaction.",
        "positive": "Monotonic growth of interlayer magnetoresistance in strong magnetic\n  field in very anisotropic layered metals: It is shown, that the monotonic part of interlayer electronic conductivity\nstrongly decreases in high magnetic field perpendicular to the conducting\nlayers. We consider only the coherent interlayer tunnelling, and the obtained\nresult strongly contradicts the standard theory. This effect appears in very\nanisotropic layered quasi-two-dimensional metals, when the interlayer transfer\nintegral is less than the Landau level separation."
    },
    {
        "anchor": "Vorticity induced negative nonlocal resistance in viscous\n  two-dimensional electron system: We report non-local electrical measurements in a mesoscopic size\ntwo-dimensional (2D) electron gas in a GaAs quantum well in a hydrodynamic\nregime. Viscous electric flow is expected to be dominant when electron-electron\ncollisions occur more often than the impurity or phonon scattering events. We\nobserve a negative nonlocal resistance and attribute it to the formation of\nwhirlpools in the electron flow. We use the different nonlocal transport\ngeometries and compare the results with a theory demonstrating the significance\nof hydrodynamics in mesoscopic samples.",
        "positive": "Anisotropic magneto-thermal transport and Spin-Seebeck effect: The angular dependence of the thermal transport in insulating or conducting\nferromagnets is derived on the basis of the Onsager reciprocity relations\napplied to a magnetic system. It is shown that the angular dependence of the\ntemperature gradient takes the same form as that of the anisotropic\nmagnetoresistance, including anomalous and planar Hall contributions. The\nmeasured thermocouple generated between the extremities of the non-magnetic\nelectrode in thermal contact to the ferromagnet follows this same angular\ndependence. The sign and amplitude of the magneto-voltaic signal is controlled\nby the difference of the Seebeck coefficients of the thermocouple."
    },
    {
        "anchor": "Anisotropic nanoscale wrinkling in solid state substrates: Pattern formation induced by wrinkling is a very common phenomenon exhibited\nin soft-matter substrates. In all these systems wrinkles develop in presence of\ncompressively stressed thin films lying on compliant substrates. Here we\ndemonstrate the controlled growth of self-organized nanopatterns exploiting a\nwrinkling instability on a solid-state substrate. Soda-lime glasses are\nmodified in the surface layers by a defocused ion beam which triggers the\nformation of a compressively stressed surface layer deprived of alkali ions.\nWhen the substrate is heated up near its glass transition temperature, the\nwrinkling instability boosts the growth rate of the pattern by about two orders\nof magnitude. High aspect ratio anisotropic ripples bound by faceted ridges are\nthus formed which represent an optimal template for guiding the growth of large\narea arrays of functional nanostructures. We demonstrate the engineering over\nlarge square cm areas of quasi-1D arrays of Au nanostripe dimers endowed with\ntunable plasmonic response, strong optical dichroism and high electrical\nconductivity. These peculiar functionalities allow to exploit these large area\nsubstrates as active metamaterials in nanophotonics, biosensing and\noptoelectronics.",
        "positive": "Universal structure of the edge states of the fractional quantum Hall\n  states: We present an effective theory for the bulk fractional quantum Hall states on\nthe Jain sequences on closed surfaces and show that it has a universal form\nwhose structure does not change from fraction to fraction. The structure of\nthis effective theory follows from the condition of global consistency of the\nflux attachment transformation on closed surfaces. We derive the theory of the\nedge states on a disk that follows naturally from this globally consistent\ntheory on a torus. We find that, for a fully polarized two-dimensional electron\ngas, the edge states for all the Jain filling fractions $\\nu=p/(2np+1)$ have\nonly one propagating edge field that carries both energy and charge, and two\nnon-propagating edge fields of topological origin that are responsible for the\nstatistics of the excitations. Explicit results are derived for the electron\nand quasiparticle operators and for their propagators at the edge. We show that\nthese operators create states with the correct charge and statistics. It is\nfound that the tunneling density of states for all the Jain states scales with\nfrequency as $|\\omega|^{(1-\\nu)/\\nu}$."
    },
    {
        "anchor": "Mie-excitons: understanding strong coupling in dielectric nanoparticles: We theoretically analyse the hybrid Mie-exciton optical modes arising from\nthe strong coupling of excitons in organic dyes or transition-metal\ndichalcogenides with the Mie resonances of high-index dielectric nanoparticles.\nDetailed analytic calculations show that silicon--exciton core--shell\nnanoparticles are characterised by a richness of optical modes which can be\ntuned through nanoparticle dimensions to produce large anticrossings in the\nvisible or near infrared, comparable to those obtained in plexcitonics. The\ncomplex magnetic-excitonic nature of these modes is understood through spectral\ndecomposition into Mie-coefficient contributions, complemented by electric and\nmagnetic near-field profiles. In the frequency range of interest, absorptive\nlosses in silicon are sufficiently low to allow observation of several periods\nof Rabi oscillations in strongly coupled emitter-particle architectures, as\nconfirmed here by discontinuous Galerkin time-domain calculations for the\nelectromagnetic field beat patterns. These results suggest that Mie resonances\nin high-index dielectrics are promising alternatives for plasmons in\nstrong-coupling applications in nanophotonics, while the coupling of magnetic\nand electric modes opens intriguing possibilities for external control.",
        "positive": "Imaging reconfigurable molecular concentration on a graphene\n  field-effect transistor: The spatial arrangement of adsorbates deposited onto a clean surface in\nvacuum typically cannot be reversibly tuned. Here we use scanning tunneling\nmicroscopy to demonstrate that molecules deposited onto graphene field-effect\ntransistors exhibit reversible, electrically-tunable surface concentration.\nContinuous gate-tunable control over the surface concentration of charged\nF4TCNQ molecules was achieved on a graphene FET at T = 4.5K. This capability\nenables precisely controlled impurity doping of graphene devices and also\nprovides a new method for determining molecular energy level alignment based on\nthe gate-dependence of molecular concentration. The gate-tunable molecular\nconcentration can be explained by a dynamical molecular rearrangement process\nthat reduces total electronic energy by maintaining Fermi level pinning in the\ndevice substrate. Molecular surface concentration in this case is fully\ndetermined by the device back-gate voltage, its geometric capacitance, and the\nenergy difference between the graphene Dirac point and the molecular LUMO\nlevel."
    },
    {
        "anchor": "A Chemical turnstile: A chemical turnstile is a device for transporting small, well-characterised\ndoses of atoms from one location to another. A working turnstile has yet to be\nbuilt, despite the numerous technological applications available for such a\ndevice. The key difficulty in manufacturing a chemical turnstile is finding a\nmedium which will trap and transport atoms. Here we propose that ferroelastic\ntwin walls are suitable for this role. Previous work shows that twin walls can\nact as two-dimensional trapping planes within which atomic transport is fast.\nWe report simulations showing that a stress-induced reorientation of a twin\nwall can occur. This behaviour is ideal for chemical turnstile applications.",
        "positive": "Nucleation of superconducting pairing states at mesoscopic scales at\n  zero temperature: We find the spin polarized disordered Fermi liquids are unstable to the\nnucleation of superconducting pairing states at mesoscopic scales even when\nmagnetic fields which polarize the spins are substantially higher than the\ncritical one. We study the probability of finding superconducting pairing\nstates at mesoscopic scales in this limit. We find that the distribution\nfunction depends only on the film conductance. The typical length scale at\nwhich pairing takes place is universal, and decreases when the magnetic field\nis increased. The number density of these states determines the strength of the\nrandom exchange interactions between mesoscopic pairing states."
    },
    {
        "anchor": "Interplay between direct and crossed Andreev reflections in hybrid\n  nano-structures: The interplay between various many body effects in a quantum dot attached to\ntwo normal and one superconducting lead is considered in the limit of large\nsuperconducting gap. By the proximity effect the superconducting lead induces\npairing correlations on the quantum dot. In the subgap region one observes the\nanomalous tunneling via direct and crossed Andreev scattering, whereas the\nusual single particle electronic transfer is suppressed. The interactions of\nelectrons on the dot leading to such phenomena as the Coulomb blockade and the\nKondo effect severely modify the currents flowing in the system. In particular:\n(i) they prevent the existence of the negative differential conductance\nobserved for non-interacting quantum dot over the whole range of voltages, (ii)\naffect the distribution of the currents as function of the applied voltage and\n(iii) lead to the appearance of additional low bias feature due to the\nformation of the Abrikosov-Suhl resonance. The non-local correlations in the\nCoulomb blockade regime are most pronounced for the particle-hole symmetric dot\nand thus can be easily tuned by means of gate voltage. They are observed even\nin the Kondo regime and dominate the behavior close to the Abrikosov-Suhl\nresonance showing convincingly that Kondo correlations do not destroy subtle\nentanglement between electrons.",
        "positive": "Diffusion equation and spin drag in spin-polarized transport: We study the role of electron-electron interactions for spin polarized\ntransport using the Boltzmann equation and derive a set of coupled transport\nequations. For spin polarized transport the electron-electron interactions are\nimportant, because they tend to equilibrate the momentum of the two spin\nspecies. This ``spin drag'' effect enhances the resistivity of the system. The\nenhancement is stronger the lower the dimension and should be measurable in for\nexample a two dimensional electron gas with ferromagnetic contacts. We also\ninclude spin flip scattering which has two effects: it equilibrates the spin\ndensity imbalance and, provided it has a non s-wave component, also the current\nimbalance."
    },
    {
        "anchor": "Noise on the Non-Abelian $\u03bd=5/2$ Fractional Quantum Hall Edge: The recent measurement of a half-integer thermal conductance for the\n$\\nu=5/2$ fractional quantum Hall state has confirmed its non-Abelian nature,\nmaking the question of the underlying topological order highly intriguing. We\nanalyze the shot noise at the edge of the three most prominent non-Abelian\ncandidate states. We show that the noise scaling with respect to the edge\nlength can, in combination with the thermal conductance, be used to\nexperimentally distinguish between the Pfaffian, anti-Pfaffian, and\nparticle-hole-Pfaffian edge structures.",
        "positive": "Topological phase transitions between chiral and helical spin textures\n  in a lattice with spin-orbit coupling and a magnetic field: We consider the combined effects of large spin-orbit couplings and a\nperpendicular magnetic field in a 2D honeycomb fermionic lattice. This system\nprovides an elegant setup to generate versatile spin textures propagating along\nthe edge of a sample. The spin-orbit coupling is shown to induce topological\nphase transitions between a helical quantum spin Hall phase and a chiral\nspin-imbalanced quantum Hall state. Besides, we find that the spin orientation\nof a single topological edge state can be tuned by a Rashba spin-orbit\ncoupling, opening an interesting route towards quantum spin manipulation. We\ndiscuss the possible realization of our results using cold atoms trapped in\noptical lattices, where large synthetic magnetic fields and spin-orbit\ncouplings can be engineered and finely tuned. In particular, this system would\nlead to the observation of a time-reversal-symmetry-broken quantum spin Hall\nphase."
    },
    {
        "anchor": "Tunneling Characteristics of an Electron-Hole Trilayer under an In-plane\n  Magnetic Field: We have studied the tunneling properties of GaSb/AlSb/InAs/AlSb/GaSb\nheterostructures, in which electrons and holes accumulate in the InAs and GaSb\nregions respectively, under a magnetic field parallel to the interfaces. The\nlow-temperature (T = 4.2K), zero-bias magnetoconductance has shown a behavior\nwith field that evidences the two-dimensional character of both electrons and\nholes and that has allowed us to determine the hole density and the\nelectron-hole separation. The observed field dependence of the current-voltage\ncharacteristics is explained by the relative change in parallel momentum of\nelectrons and holes induced by the field.",
        "positive": "Orbital fluctuations and strong correlations in quantum dots: In this lecture note we focus our attention to quantum dot systems where\nexotic strongly correlated behavior develops due to the presence of orbital or\ncharge degrees of freedom. After giving a concise overview of the theory of\ntransport and Kondo effect through a single electron transistor, we discuss how\nSU(4) Kondo effect develops in dots having orbitally degenerate states and in\ndouble dot systems, and then study the singlet-triplet transition in lateral\nquantum dots. Charge fluctuations and Matveev's mapping to the two-channel\nKondo model in the vicinity of charge degeneracy point are also discussed."
    },
    {
        "anchor": "Local Density of States around an Impurity in a Strong Magnetic Field.\n  I. a Two-Dimensional System with Parabolic Dispersion: Bound states around an impurity are investigated for a two dimensional\nelectron system in a strong magnetic field. Long-range Coulomb potential and\nrelated potentials are considered. Schr\\\"odinger equation is solved numerically\nto obtain the bound states. The energy and wave function of these bound states\nare indirectly observed by the scanning tunneling spectroscopy as local density\nof states (LDOS). Theoretically obtained LDOS is compared with experiment.\nReasonable agreement is obtained.",
        "positive": "Polyyne Electronic and Vibrational Properties under Environmental\n  Interactions: Recently, the novel system of linear carbon chains inside of double-walled\ncarbon nanotubes has extended the length of $sp^1$ hybridized carbon chains\nfrom 44 to thousands of atoms [L. Shi et al., Nat. Mater. 15, 634 (2016)]. The\noptoelectronic properties of these ultra-long chains are poorly described by\ncurrent theoretical models, which are based on short chain experimental data\nand assume a constant environment. As such, a physical understanding of the\nsystem in terms of charge transfer and van der Waals interactions is widely\nmissing. We provide a reference for the intrinsic Raman frequency of polyynes\nin vacuo and explicitly describe the interactions between polyynes and carbon\nnanotubes. We find that van der Waals interactions strongly shift the Raman\nfrequency, which has been neither expected nor addressed before. As a\nconsequence of charge transfer from the tube to the chain, the Raman response\nof long chains is qualitatively different from the known phonon dispersion of\npolymers close to the $\\Gamma$-point. Based on these findings we show how to\ncorrectly interpret the Raman data, considering the nanotube's properties. This\nis essential for its use as an analytical tool to optimize the growth process\nfor future applications."
    },
    {
        "anchor": "Magic in twisted transition metal dichalcogenide bilayers: The long wavelength moir\\'e superlattices in twisted 2D structures have\nemerged as a highly tunable platform for strongly correlated electron physics.\nWe study the moir\\'e bands in twisted transition metal dichalcogenide\nhomobilayers, focusing on WSe$_2$, at small twist angles using a combination of\nfirst principles density functional theory, continuum modeling, and\nHartree-Fock approximation. We reveal the rich physics at small twist angles\n$\\theta<4^\\circ$, and identify a particular magic angle at which the top\nvalence moir\\'e band achieves almost perfect flatness. In the vicinity of this\nmagic angle, we predict the realization of a generalized Kane-Mele model with a\ntopological flat band, interaction-driven Haldane insulator, and Mott\ninsulators at the filling of one hole per moir\\'e unit cell. The combination of\nflat dispersion and uniformity of Berry curvature near the magic angle holds\npromise for realizing fractional quantum anomalous Hall effect at fractional\nfilling. We also identify twist angles favorable for quantum spin Hall\ninsulators and interaction-induced quantum anomalous Hall insulators at other\ninteger fillings.",
        "positive": "Charge Transport Behavior of 1D Gold Chiral Nanojunctions: Understanding the process of electron tunneling in chirality-induced\nsingle-molecule junctions is imperative for the development of nanoscale\nswitching and artificial nanomotors. Based on the combined non-equilibrium\nGreen functions formalism and the ground-state density functional theory, we\npresent here the charge transport behavior of chiral gold (7,3) nanowires (NWs)\nin comparison with various other chiral and achiral 1D gold nanostructures as\nthe principal leads to form stable single-molecule junctions. For\nsigma-saturated alkane chains, we find that the contact potential barriers vary\nwidely with the achiral leads but not with the chiral ones, although a close\nresemblance exists in the tunneling constants. Lower energy gaps for\nsingle-molecule junctions with Au(7,3)NWs ensure better electronic conductance\neven after allowing for the low thermal loss, due mainly to the close-packed\narrangements of atoms with minimum wire tension. Our first-principles quantum\ntransport analysis further suggests that chiral Au(7,3)NWs render higher\nelectronic conductance than chiral gold (5,3) nanotubes (NTs), once bridged by\neither sigma-saturated or pi-conjugated molecular moieties. It, however, turns\nout that asymmetricity in the characteristics of channel formation at the\nlead-molecule contact remains often associated with chiral Au(7,3)NWs only."
    },
    {
        "anchor": "Effects of Boundary on Orbital Magnetization for a Bilayer System with\n  Different Chern Numbers: The real space formalism of orbital magnetization (OM) is an average of the\nlocal OM over some appropriate region of the system. Previous studies prefer a\nbulk average (i.e., without including boundaries). Based on a bilayer model\nwith an adjustable Chern number at half filling, we numerically investigate the\neffects from boundaries on the real space expressions of OM. The size\nconvergence processes of its three constituent terms $M_{\\mathrm{LC}}$,\n$M_{\\mathrm{IC}}$, $M_{\\mathrm{BC}}$ are analysed. The topological term\n$M_{\\mathrm{BC}}$ makes a nonnegligible contribution from boundaries as a\nmanifestation of edge states, especially in the case of nonzero Chern numbers.\nHowever, we show that the influence of the boundary on $M_{\\mathrm{LC}}$ and\n$M_{\\mathrm{IC}}$ exactly compensates that on $M_{\\mathrm{BC}}$. This\ncompensation effect leads to the conclusion that the whole sample average is\nalso a correct algorithm in the thermodynamic limit, which gives the same value\nas those from the bulk average and the $k$ space formula. This clarification\nwill be beneficial to further studies on orbitronics, as well as the orbital\nmagnetoelectric effects in higher dimensions.",
        "positive": "Non-linear model of impurity diffusion in nanoporous materials upon\n  ultrasonic treatment: Non-linear theory of diffusion of impurities in porous materials upon\nultrasonic treatment is described. It is shown that at a defined value of\ndeformation amplitude, an average concentration of vacancies and temperature as\na result of the effect of ultrasound possibly leads to the formation of\nnanoclusters of vacancies and to their periodic educations in porous materials.\nIt is shown that at a temperature smaller than some critical value, a\nsignificant growth of a diffusion coefficient is observed in porous materials."
    },
    {
        "anchor": "Spin-dependent transport and current modulation in a current-in-plane\n  field-effect transistor: We propose a current-in-plane spin-valve field-effect transistor\n(CIP-SV-FET), which is composed of a ferromagnet / nonferromagnet / ferromagnet\ntrilayer structure and a gate electrode. This is a promising device alternative\nto spin metal-oxide-semiconductor field-effect transistors. Here, we fabricate\na ferromagnetic-semiconductor GaMnAs-based CIP-SV-FET and demonstrate its basic\noperation of the resistance modulation both by the magnetization configuration\nand by the gate electric field. Furthermore, we present the\nelectric-field-assisted magnetization reversal in this device.",
        "positive": "Stable quantum dots in an InSb two-dimensional electron gas: Indium antimonide (InSb) two-dimensional electron gases (2DEGs) have a unique\ncombination of material properties: high electron mobility, strong spin-orbit\ninteraction, large Land\\'{e} g-factor, and small effective mass. This makes\nthem an attractive platform to explore a variety of mesoscopic phenomena\nranging from spintronics to topological superconductivity. However, there exist\nlimited studies of quantum confined systems in these 2DEGs, often attributed to\ncharge instabilities and gate drifts. We overcome this by removing the\n$\\delta$-doping layer from the heterostructure, and induce carriers\nelectrostatically. This allows us to perform the first detailed study of stable\ngate-defined quantum dots in InSb 2DEGs. We demonstrate two distinct strategies\nfor carrier confinement and study the charge stability of the dots. The small\neffective mass results in a relatively large single particle spacing, allowing\nfor the observation of an even-odd variation in the addition energy. By\ntracking the Coulomb oscillations in a parallel magnetic field we determine the\nground state spin configuration and show that the large g-factor ($\\sim$30)\nresults in a singlet-triplet transition at magnetic fields as low as 0.3 T."
    },
    {
        "anchor": "Electronic Structure in Gapped Graphene with Coulomb Potential: In this paper, we numerically study the bound electron states induced by long\nrange Coulomb impurity in gapped graphene and the quasi-bound states in\nsupercritical region based on the lattice model. We present a detailed\ncomparison between our numerical simulations and the prediction of the\ncontinuum model which is described by the Dirac equation in (2+1)-dimensional\nQuantum Electrodynamics (QED). We also use the Fano's formalism to investigate\nthe quasi-bound state development and design an accessible experiments to test\nthe decay of the supercritical vacuum in the gapped graphene.",
        "positive": "Highly efficient two photon generation from a coherently pumped quantum\n  dot embedded in a microcavity: We propose a scheme to realize a highly efficient solid state source of\nphoton pairs using cavity-assisted stimulated Raman adiabatic passage (STIRAP)\nin a single quantum dot, where a single photon from pump pulse and two stokes\nphotons from cavity mode drives the Raman transition. The Autler-Townes\ndoublet, generated by using a resonant continuous wave laser between biexciton\nand exciton states, and two-photon-resonant transition through strongly coupled\ncavity mode are utilized to facilitate (1+2)type Raman transition in the\nquantum dot. We show in the case of weak pump although the probability of\ngenerating two photons in cavity mode is small without cavity damping but\ntwo-photon-resonant emission is enhanced by cavity damping within strong\ncoupling regime. We also discuss spectrum of the generated photon pair and\nphoton-photon correlations in the generated photon pair. The efficiency of two\nphoton source could be more than 80\\% in current experimental conditions."
    },
    {
        "anchor": "Proton transport through nanoscale corrugations in two-dimensional\n  crystals: Defect-free graphene is impermeable to all atoms and ions at ambient\nconditions. Experiments that can resolve gas flows of a few atoms per hour\nthrough micrometre-sized membranes found that monocrystalline graphene is\ncompletely impermeable to helium, the smallest of atoms. Such membranes were\nalso shown to be impermeable to all ions, including the smallest one, lithium.\nOn the other hand, graphene was reported to be highly permeable to protons,\nnuclei of hydrogen atoms. There is no consensus, however, either on the\nmechanism behind the unexpectedly high proton permeability or even on whether\nit requires defects in graphene's crystal lattice. Here using high resolution\nscanning electrochemical cell microscopy (SECCM), we show that, although proton\npermeation through mechanically-exfoliated monolayers of graphene and hexagonal\nboron nitride cannot be attributed to any structural defects, nanoscale\nnon-flatness of 2D membranes greatly facilitates proton transport. The spatial\ndistribution of proton currents visualized by SECCM reveals marked\ninhomogeneities that are strongly correlated with nanoscale wrinkles and other\nfeatures where strain is accumulated. Our results highlight nanoscale\nmorphology as an important parameter enabling proton transport through 2D\ncrystals, mostly considered and modelled as flat, and suggest that strain and\ncurvature can be used as additional degrees of freedom to control the proton\npermeability of 2D materials.",
        "positive": "Spin fluctuations of non-equilibrium electrons and excitons in\n  semiconductors: Effects related with deviations from thermodynamic equilibrium take a special\nplace in the modern physics. Among those, non-equilibrium phenomena in quantum\nsystems attract the highest interest. To date, the experimental technique of\nspin noise spectroscopy has became quite widespread, which makes possible to\nobserve spin fluctuations of charge carriers in semiconductors both in\nequilibrium and non-equilibrium conditions. It calls for development of the\ntheory of spin fluctuations of electrons and electron-hole complexes for\nnon-equilibrium conditions. In this paper we consider a range of physical\nsituations where a deviation from an equilibrium becomes pronounced in the spin\nnoise. A general method of calculation of electron and exciton spin\nfluctuations in non-equilibrium state is proposed. A short review of\ntheoretical and experimental results in this area is given."
    },
    {
        "anchor": "Large-Area Nanopatterned Graphene For Ultrasensitive Gas Sensing: Chemical vapor deposited graphene is nanopatterned by a spherical\nblock-copolymer etch mask. The use of spherical rather than cylindrical block\ncopolymers allows homogeneous patterning of cm-scale areas without any\nsubstrate surface treatment. Raman spectroscopy was used to study the\ncontrolled generation of point defects in the graphene lattice with increasing\netching time, confirming that alongside the nanomesh patterning, the\nnanopatterned CVD graphene presents a high defect density between the mesh\nholes. The nanopatterned samples showed sensitivities for NO2 of more than one\norder of magnitude higher than for non-patterned graphene. NO2 concentrations\nas low as 300 ppt were detected with an ultimate detection limit of tens of\nppt. This is so far the smallest value reported for not UV illuminated graphene\nchemiresistive NO2 gas sensors. The drastic improvement in the gas sensitivity\nis believed to be due to the high adsorption site density, thanks to the\ncombination of edge sites and point defect sites. This work opens the\npossibility of large area fabrication of nanopatterned graphene with extreme\ndensity of adsorption sites for sensing applications.",
        "positive": "Tutorial: Dirac Equation Perspective on Higher-Order Topological\n  Insulators: In this tutorial, we pedagogically review recent developments in the field of\nnon-interacting fermionic phases of matter, focussing on the low energy\ndescription of higher-order topological insulators in terms of the Dirac\nequation. Our aim is to give a mostly self-contained treatment. After\nintroducing the Dirac approximation of topological crystalline band structures,\nwe use it to derive the anomalous end and corner states of first- and\nhigher-order topological insulators in one and two spatial dimensions. In\nparticular, we recast the classical derivation of domain wall bound states of\nthe Su-Schrieffer-Heeger (SSH) chain in terms of crystalline symmetry. The edge\nof a two-dimensional higher-order topological insulators can then be viewed as\na single crystalline symmetry-protected SSH chain, whose domain wall bound\nstates become the corner states. We never explicitly solve for the full\nsymmetric boundary of the two-dimensional system, but instead argue by\nadiabatic continuity. Our approach captures all salient features of\nhigher-order topology while remaining analytically tractable."
    },
    {
        "anchor": "Quantum Anomalous Hall Effect in Graphene Proximity Coupled to an\n  Antiferromagnetic Insulator: We propose realizing the quantum anomalous Hall effect by proximity coupling\ngraphene to an antiferromagnetic insulator that provides both broken\ntime-reversal symmetry and spin-orbit coupling. We illustrate our idea by\nperforming ab initio calculations for graphene adsorbed on the (111) surface of\nBiFeO3. In this case, we find that the proximity-induced exchange field in\ngraphene is about 70 meV, and that a topologically nontrivial band gap is\nopened by Rashba spin-orbit coupling. The size of the gap depends on the\nseparation between the graphene and the thin film substrate, which can be tuned\nexperimentally by applying external pressure.",
        "positive": "Tunnel barrier design in donor nanostructures defined by hydrogen-resist\n  lithography: A four-terminal donor quantum dot (QD) is used to characterize potential\nbarriers between degenerately doped nanoscale contacts. The QD is fabricated by\nhydrogen-resist lithography on Si(001) in combination with $n$-type doping by\nphosphine. The four contacts have different separations ($d$ = 9, 12, 16 and 29\nnm) to the central 6 nm $\\times$ 6 nm QD island, leading to different tunnel\nand capacitive coupling. Cryogenic transport measurements in the\nCoulomb-blockade (CB) regime are used to characterize these tunnel barriers. We\nfind that field enhancement near the apex of narrow dopant leads is an\nimportant effect that influences both barrier breakdown and the magnitude of\nthe tunnel current in the CB transport regime. From CB-spectroscopy\nmeasurements, we extract the mutual capacitances between the QD and the four\ncontacts, which scale inversely with the contact separation $d$. The\ncapacitances are in excellent agreement with numerical values calculated from\nthe pattern geometry in the hydrogen resist. We show that by engineering the\nsource-drain tunnel barriers to be asymmetric, we obtain a much simpler\nexcited-state spectrum of the QD, which can be directly linked to the orbital\nsingle-particle spectrum."
    },
    {
        "anchor": "Non-Linear hydrodynamics and Fractionally Quantized Solitons at\n  Fractional Quantum Hall Edge: We argue that dynamics of gapless Fractional Quantum Hall Edge states is\nessentially non-linear and that it features fractionally quantized solitons\npropagating along the edge. Observation of solitons would be a direct evidence\nof fractional charges. We show that the non-linear dynamics of the Laughlin's\nFQH state is governed by the quantum Benjamin-Ono equation. Non-linear dynamics\nof gapless edge states is determined by gapped modes in the bulk of FQH liquid.\nThe dispersion of edge modes is traced to the double boundary layer of FQH\nstates.",
        "positive": "Topological end states due to inhomogeneous strains in wrinkled\n  semiconducting ribbons: We show that curvature-induced inhomogeneous strain distributions in\nnanoscale buckled semiconducting ribbons lead to the existence of end states\nwhich are topologically protected by inversion symmetry. These end-state\ndoublets, corresponding to the so-called Maue-Shockley states, are robust\nagainst weak disorder. By identifying and calculating the corresponding\ntopological invariants, we further show that a buckled semiconducting ribbon\nundergoes topological phase transitions between trivial and non-trivial\ninsulating phases by varying its real space geometry."
    },
    {
        "anchor": "Decoherence, Autler-Townes effect, and dark states in two-tone driving\n  of a three-level superconducting system: We present a detailed theoretical analysis of a multi-level quantum system\ncoupled to two radiation fields and subject to decoherence. We concentrate on\nan effect known from quantum optics as the Autler-Townes splitting, which has\nbeen recently demonstrated experimentally [M. A. Sillanpaa et al., Phys. Rev.\nLett. 103, 193601 (2009)] in a superconducting phase qubit. In the three-level\napproximation, we derive analytical solutions and describe how they can be used\nto extract the decoherence rates and to account for the measurement data.\nBetter agreement with the experiment can be obtained by extending this model to\nfive levels. Finally, we investigate the stationary states created in the\nexperiment and show that their structure is close to that of dark states.",
        "positive": "Collapse of Landau levels in Weyl semimetals: It is known that in two dimensional relativistic Dirac systems, the Landau\nlevels can collapse in the presence of a critical in plane electric field. We\nextend this mechanism to the three dimensional Weyl semimetals and analyze the\nphysical consequences for the cases of both, real and pseudo Landau levels\narising form strain induced elastic magnetic fields."
    },
    {
        "anchor": "Doping of Graphene Nanoribbons via Functional Group Edge Modification: We report on the on-surface synthesis of 7 armchair graphene nanoribbons\n(7-AGNRs) substituted with nitrile (CN) functional groups. The CN groups are\nattached to the GNR backbone by modifying the 7-AGNR precursor. While many of\nthese groups survive the on-surface synthesis, the reaction process causes the\ncleavage of some CN from the ribbon backbone and the on-surface\ncycloisomerization of few nitriles onto pyridine rings. Scanning Tunneling\nSpectroscopy and Density Functional Theory reveal that CN groups behave as very\nefficient n-dopants, significantly downshifting the bands of the ribbon, and\nintroducing deep impurity levels associated to the nitrogen electron lone\npairs.",
        "positive": "Thermal transport in suspended silicon membranes measured by\n  laser-induced transient gratings: Studying thermal transport at the nanoscale poses formidable experimental\nchallenges due both to the physics of the measurement process and to the issues\nof accuracy and reproducibility. The laser-induced transient thermal grating\n(TTG) technique permits non-contact measurements on nanostructured samples\nwithout a need for metal heaters or any other extraneous structures, offering\nthe advantage of inherently high absolute accuracy. We present a review of\nrecent studies of thermal transport in nanoscale silicon membranes using the\nTTG technique. An overview of the methodology, including an analysis of\nmeasurements errors, is followed by a discussion of new findings obtained from\nmeasurements on both solid and nanopatterned membranes. The most important\nresults have been a direct observation of non-diffusive phonon-mediated\ntransport at room temperature and measurements of thickness-dependent thermal\nconductivity of suspended membranes across a wide thickness range, showing good\nagreement with first-principles-based theory assuming diffuse scattering at the\nboundaries. Measurements on a membrane with a periodic pattern of nanosized\nholes indicated fully diffusive transport and yielded thermal diffusivity\nvalues in agreement with Monte Carlo simulations. Based on the results obtained\nto-date, we conclude that room-temperature thermal transport in membranebased\nsilicon nanostructures is now reasonably well understood."
    },
    {
        "anchor": "Quantization of spin Hall conductivity in two-dimensional topological\n  insulators versus symmetry and spin-orbit interaction: The third-rank tensor of the static spin Hall conductivity is investigated\nfor two-dimensional (2D) topological insulators by electronic structure\ncalculations. Its seeming quantization is numerically demonstrated for highly\nsymmetric systems independent of the gap size. 2D crystals with hexagonal and\nsquare Bravais lattice show similar effects, while true rectangular\ntranslational symmetry yields conductivity values much below the quantum\n$e^2/h$. Field-induced lifting the inversion symmetry does not influence the\nquantum spin Hall state up to band inversion but the conductivity quantization.\nWeak symmetry-conserving biaxial but also uniaxial strain has a minor influence\nas long as inverted gaps dictate the topological character. The results are\ndiscussed in terms of the atomic geometry and the Rashba contribution to the\nspin-orbit interaction (SOI). Translational and point-group symmetry as well as\nSOI rule the deviation from the quantization of the spin Hall conductance.",
        "positive": "Predicted antiferromagnetic-vortex dynamics driven by spin polarized\n  current in thin discs: We investigate vortex configuration in antiferromagnetic thin discs. It is\nshown that the vortex acquires oscillatory dynamics with well-defined amplitude\nand frequency which may be controlled on demand by an alternating spin\npolarized current. These findings may be useful for the emerging field of\nantiferromagnetic topological spintronics, once vortex dynamics may be\ncontrolled by purely electric means."
    },
    {
        "anchor": "Probing the Ginzburg-Landau Potential for Lasers Using Higher-order\n  Photon Correlations: Lasing transition is known to be analogous to the second-order phase\ntransition. Furthermore, for some cases, it is possible to define the\nGinzburg-Landau (GL) potential, and the GL theory predicts the photon\nstatistical properties of lasers. However, the GL potential for lasers is\nsurprising, because lasers are operating far from equilibrium. In this paper,\nwe theoretically examine the validity of the GL theory for lasers in terms of\nvarious parameters, particularly, the ratio between photon and carrier\nlifetimes. For this purpose, we use stochastic rate equations and higher-order\nphoton correlation functions. With higher-order photon correlation\nmeasurements, we can check whether or not laser dynamics are described by the\nGL theory. We demonstrate that, for low-$\\beta$ lasers, the GL theory is\napplicable even when the photon lifetime is comparable to the carrier lifetime\nand that photon-carrier relaxation oscillation is the fundamental origin of the\nbreakdown of the GL theory, which can be understood in the framework of center\nmanifold reduction.",
        "positive": "Electric field control of interaction between magnons and quantum spin\n  defects: Hybrid systems coupling quantum spin defects (QSD) and magnons can enable\nunique spintronic device functionalities and probes for magnetism. Here, we add\nelectric field control of magnon-QSD coupling to such systems by integrating\nferromagnet-ferroelectric multiferroic with nitrogen-vacancy (NV) center spins.\nCombining quantum relaxometry with ferromagnetic resonance measurements and\nanalytical modeling, we reveal that the observed electric-field tuning results\nfrom ferroelectric polarization control of the magnon-generated fields at the\nNV. Exploiting the demonstrated control, we also propose magnon-enhanced hybrid\nelectric field sensors with improved sensitivity."
    },
    {
        "anchor": "Effects of van der Waals interaction on the N$_2$ adsorption on carbon\n  nanotubes: proposal of new force field parameters: The separation of carbon dioxide CO$_2$ from nitrogen gas (N$_2$), the main\ncomponent of flue gas, has become an emerging action to mitigate climate\nchange. Feasible and efficient approaches to exploring the separation\nproperties of materials are molecular dynamics (MD) and Monte Carlo (MC)\nsimulations. In these approaches, a careful choice of force fields is required\nto avoid unrealistic predictions of thermodynamic properties. However, most\nstudies use Lorentz-Berthelot combining rules (LB) to obtain the interaction\nbetween different species, an approximation that could not capture the essence\nof interfacial interactions. In this context, we verified how accurate LB is in\ndescribing the interaction of N$_2$ molecules and carbon nanostructures by\ncomparing the interaction energies from LB with those from density functional\ntheory (DFT) calculations. We selected carbon nanomaterials because they are\nconsidered promising materials to perform N$_2$/CO$_2$ separation. The results\nshow that the LB underestimates the interaction energies and affects the\nprediction of fundamental properties of solid-fluid interfacial interactions.\nTo overcome this limitation, we parametrized a Lennard-Jones potential using\nenergies and forces from DFT, obtained through the van der Waals functional\nKBM. The proposed potential show good transferability and agreement to\nab-initio calculations. Grand Canonical Monte Carlo simulations were performed\nto verify the effects of employing LB in predicting the amount of nitrogen gas\nadsorbed inside different CNTs. LB predicts a lower density inside them.\nMoreover, our results suggest that LB leads to a different characterization of\nthe adsorption properties of carbon nanotubes, by changing significantly the\nadsorption isotherm.",
        "positive": "Zeeman term for the N\u00e9el vector in a two sublattice antiferromagnet\n  using Dzyaloshinsky-Moriya interaction and magnetic field: We theoretically investigate the dynamics of solitons in two sublattice\nantiferromagnets under external perturbations, focusing on the effect of\nDzyaloshinsky-Moriya (DM) interactions. To this end, we construct a\nmicromagnetic field theory for the antiferromagnet in the presence of the\nexternal magnetic field, DM interaction, and spin-transfer torque. In\nparticular, we show external magnetic field and spin current couple to N\\'eel\nvector in a Zeeman-like manner when DM interactions present, which can be used\nto efficiently drive antiferromagnetic solitons of different dimensions.\nBesides, we study the effect of straining the local lattice. It can serve as an\nexternal handle on the N\\'eel field inertia and thus dynamical properties. Our\nfindings may find applications in antiferromagnetic spintronics."
    },
    {
        "anchor": "Spin Torque Ferromagnetic Resonance Induced by the Spin Hall Effect: We demonstrate that the spin Hall effect in a thin film with strong\nspin-orbit scattering can excite magnetic precession in an adjacent\nferromagnetic film. The flow of alternating current through a Pt/NiFe bilayer\ngenerates an oscillating transverse spin current in the Pt, and the resultant\ntransfer of spin angular momentum to the NiFe induces ferromagnetic resonance\n(FMR) dynamics. The Oersted field from the current also generates an FMR signal\nbut with a different symmetry. The ratio of these two signals allows a\nquantitative determination of the spin current and the spin Hall angle.",
        "positive": "Energy transfer from an individual quantum dot to a carbon nanotube: A detailed understanding of energy transduction is crucial for achieving\nprecise control of energy flow in complex, integrated systems. In this context,\ncarbon nanotubes (CNTs) are intriguing model systems due to their rich,\nchirality-dependent electronic and optical properties. Here, we study the\nquenching of fluorescence from isolated quantum dots (QDs) upon approach of\nindividual CNTs attached to atomic force microscope probes. Precision\nmeasurements of many different CNT/QD pairs reveal behavior consistent with\nresonant energy transfer between QD and CNT excitons via a Fohrster-like\ndipole-dipole coupling. The data reveal large variations in energy transfer\nlength scales even though peak efficiencies are narrowly distributed around\n96%. This saturation of efficiency is maintained even when energy transfer must\ncompete with elevated intrinsic non-radiative relaxation rates during QD aging.\nThese observations suggest that excitons can be created at different locations\nalong the CNT length, thereby resulting in self-limiting behavior."
    },
    {
        "anchor": "A Three-dimensional simulation study of the performance of Carbon\n  Nanotube Field Effect Transistors with doped reservoirs and realistic\n  geometry: In this work, we simulate the expected device performance and the scaling\nperspectives of Carbon nanotube Field Effect Transistors (CNT-FETs), with doped\nsource and drain extensions. The simulations are based on the self-consistent\nsolution of the 3D Poisson-Schroedinger equation with open boundary conditions,\nwithin the Non-Equilibrium Green's Function formalism, where arbitrary gate\ngeometry and device architecture can be considered. The investigation of short\nchannel effects for different gate configurations and geometry parameters shows\nthat double gate devices offer quasi ideal subthreshold slope and DIBL without\nextremely thin gate dielectrics. Exploration of devices with parallel CNTs show\nthat On currents per unit width can be significantly larger than the silicon\ncounterpart, while high-frequency performance is very promising.",
        "positive": "Transport properties of an interacting Majorana chain: We study a one-dimensional (1D) chain of $2N$ Majorana bound states, which\ninteract through a local quartic interaction. This model describes for example\nthe edge physics of a quasi 1D stack of $2N$ Kitaev chains with modified\ntime-reversal symmetry $T\\gamma_iT^{-1}=\\gamma_i$, which precludes the presence\nof quadratic coupling. The ground state of our 1D Majorana chain displays a\nfour-fold periodicity in $N$, corresponding to the four distinct topological\nclasses of the stacked Kitaev chains. We analyze the transport properties of\nthe 1D Majorana chain, when probed by local conductors located at its ends. We\nfind that for finite but large $N$, the scattering matrix partially reflects\nthe four-fold periodicity, and the chain exhibits strikingly different\ntransport properties for different chain lengths. In the thermodynamic limit,\nthe 1D Majorana chain hosts a robust many-body zero mode, which indicates that\nthe corresponding stacked two-dimensional bulk system realizes a weak\ntopological phase."
    },
    {
        "anchor": "Energy emanating from the molecular nanomagnet Fe$_{8}$ revisited: In the molecular nanomagnet Fe$_{8}$ tunneling can occur from a metastable\nstate to an excited state followed by a transition to the ground state. This\ntransition is accompanied by an energy release of $115.6$GHz. We constructed an\nexperimental setup to measure whether this energy is released in the form of\nthermal or electromagnetic energy. Contrary to a previous publication we find\nno evidence for release of electromagnetic radiation. Our results for\ntransitions between the first and second excited states to the ground state are\nconsistent with a release of only thermal energy. This energy release extends\nfor a longer time for the second excited state than for the first excited\nstate.",
        "positive": "3D Analytical Model of Skyrmions and Skyrmion-like Structures in a\n  Two-sublattice Antiferromagnet with Dzyaloshinskii-Moriya Interaction: The analytical model is developed for description of skyrmions and\nskyrmion-like magnetic structures in a two-sublattice antiferromagnet with\nuniaxial magnetic anisotropy and Dzyaloshinskii-Moriya interaction.\nRelativistic contraction of skyrmion size in the direction of motion is\ndemonstrated for subcritical case when the skyrmion velocity is less than spin\nwave velocity in antiferromagnet. Lorentz-like supercritical transformation are\nfound for skyrmion-like magnetic structures moving with velocity greater than\nspin wave velocity in antiferromagnet."
    },
    {
        "anchor": "Entropy per particle spikes in the transition metal dichalcogenides: We derive a general expression for the entropy per particle as a function of\nchemical potential, temperature and gap magnitude for the single layer\ntransition metal dichalcogenides. The electronic excitations in these materials\ncan be approximately regarded as two species of the massive or gapped Dirac\nfermions. Inside the smaller gap there is a region with zero density of states\nwhere the dependence of the entropy per particle on the chemical potential\nexhibits a huge dip-and-peak structure. The edge of the larger gap is\naccompanied by the discontinuity of the density of states that results in the\npeak in the dependence of the entropy per particle on the chemical potential.\nThe specificity of the transition metal dichalcogenides makes possible the\nobservation of these features at rather high temperatures order of 100 K. The\ninfluence of the uniaxial strain on the entropy per particle is discussed.",
        "positive": "Efficient and realistic device modeling from atomic detail to the\n  nanoscale: As semiconductor devices scale to new dimensions, the materials and designs\nbecome more dependent on atomic details. NEMO5 is a nanoelectronics modeling\npackage designed for comprehending the critical multi-scale, multi-physics\nphenomena through efficient computational approaches and quantitatively\nmodeling new generations of nanoelectronic devices as well as predicting novel\ndevice architectures and phenomena. This article seeks to provide updates on\nthe current status of the tool and new functionality, including advances in\nquantum transport simulations and with materials such as metals, topological\ninsulators, and piezoelectrics."
    },
    {
        "anchor": "Enhanced magnetism of Cu$_n$ clusters capped with N and endohedrally\n  doped with Cr: The focus of our work is on the production of highly magnetic materials out\nof Cu clusters. We have studied the relative effects of N-capping as well as N\nmono-doping on the structural stability and electronic properties of the small\nCu clusters using first principles density functional theory based electronic\nstructure calculations.\n  We find that the N-capped clusters are more promising in producing giant\nmagnetic moments, such as 14 $\\mu_B$ for the Cu$_6$N$_6$ cluster and 29 $\\mu_B$\nfor the icosahedral Cu$_{13}$N$_{12}$ clusters. This is accompanied by a\nsubstantial enhancement in their stability. We suggest that these giant\nmagnetic moments of the capped Cu$_n$ clusters have relevance to the observed\nroom temperature ferromagnetism of Cu doped GaN. For cage-like hollow\nCu-clusters, an endohedral Cr-doping together with the N-capping appears as the\nmost promising means to produce stable giant magnetic moments in the copper\nclusters.",
        "positive": "Can the interface between a non-ideal ferromagnet and a semiconductor\n  quantum wire acts as an ideal spin filter?: The problem of spin injection across the interface between a non-ideal\nferromagnet (less than 100% spin polarization) and a semiconductor\n(paramagnetic) quantum wire is examined in the presence of Rashba spin orbit\ncoupling and an axial magnetic field along the wire axis. The field is caused\nby the ferromagnet magnetized along the wire axis. At low temperatures and for\ncertain injection energies, the interface can act as an ideal spin filter\nallowing injection only from the majority spin band of the ferromagnet. Thus,\n100% spin filtering can take place even if the ferromagnet itself is less than\n100% spin polarized. Below a critical value of the magnetic field, there are\ntwo injection energies for which ideal (100%) spin filtering is possible; above\nthis critical field, there is only one such injection energy."
    },
    {
        "anchor": "Electrical Probing of Field-Driven Cascading Quantized Transitions of\n  Skyrmion Cluster States in MnSi Nanowires: Magnetic skyrmions are topologically stable whirlpool-like spin textures that\noffer great promise as information carriers for future ultra-dense memory and\nlogic devices1-4. To enable such applications, particular attention has been\nfocused on the skyrmions properties in highly confined geometry such as one\ndimensional nanowires5-8. Hitherto it is still experimentally unclear what\nhappens when the width of the nanowire is comparable to that of a single\nskyrmion. Here we report the experimental demonstration of such scheme, where\nmagnetic field-driven skyrmion cluster (SC) states with small numbers of\nskyrmions were demonstrated to exist on the cross-sections of ultra-narrow\nsingle-crystal MnSi nanowires (NWs) with diameters, comparable to the skyrmion\nlattice constant (18 nm). In contrast to the skyrmion lattice in bulk MnSi\nsamples, the skyrmion clusters lead to anomalous magnetoresistance (MR)\nbehavior measured under magnetic field parallel to the NW long axis, where\nquantized jumps in MR are observed and directly associated with the change of\nthe skyrmion number in the cluster, which is supported by Monte Carlo\nsimulations. These jumps show the key difference between the clustering and\ncrystalline states of skyrmions, and lay a solid foundation to realize\nskyrmion-based memory devices that the number of skyrmions can be counted via\nconventional electrical measurements.",
        "positive": "Opening an energy gap in an electron double layer system at integer\n  filling factor in a tilted magnetic field: We employ magnetocapacitance measurements to study the spectrum of a double\nlayer system with gate-voltage-tuned electron density distributions in tilted\nmagnetic fields. For the dissipative state in normal magnetic fields at filling\nfactor $\\nu=3$ and 4, a parallel magnetic field component is found to give rise\nto opening a gap at the Fermi level. We account for the effect in terms of\nparallel-field-caused orthogonality breaking of the Landau wave functions with\ndifferent quantum numbers for two subbands."
    },
    {
        "anchor": "Diffuson contribution to anomalous Hall effect in disordered Co2FeSi\n  thin films: A wide variation in the disorder strength, as inferred from an order of\nmagnitude variation in the longitudinal resistivity of Co2FeSi (CFS) Huesler\nalloy thin films of fixed (50 nm) thickness, has been achieved by growing these\nfilms on Si(111) substrates at substrate temperatures ranging from room\ntemperature (RT) to 600 C. An in-depth study of the influence of disorder on\nanomalous Hall resistivity,longitudinal resistivity(LR) and magnetoresistance,\nenabled by this approach, reveals the following. The side-jump mechanism gives\na dominant contribution to anomalous Hall resistivity (AHR) in the CFS thin\nfilms, regardless of the degree of disorder present. A new and novel\ncontribution to both LR and AHR characterized by the logarithmic temperature\ndependence at temperatures below the minimum, exclusive to the amorphous CFS\nfilms, originates from the scattering of conduction electrons from the\ndiffusive hydrodynamic modes associated with the longitudinal component of\nmagnetization, called diffusons. In these amorphous CFS films, the\nelectron-diffuson, e d, scattering and weak localization (WL) mechanisms\ncompete with that arising from the inelastic electron magnon, e m, scattering\nto produce the minimum in longitudinal resistivity, whereas the minimum in AHR\nis caused by the competing contributions from the e d and e m scattering, as WL\ndoes not make any contribution to AHR. In sharp contrast, in crystalline films,\nenhanced electron electron Coulomb interaction (EEI), which is basically\nresponsible for the resistivity minimum, makes no contribution to AHR with the\nresult that AHR does not exhibit a minimum.",
        "positive": "Higher order topological matter and fractional chiral states: We develop a chiral anomalous fermion hamiltonian proposal to study the\nhigher order topological (HOT) phase with chiral symmetry $\\mathcal{C}$\nfractionalized like $\\mathcal{C}_{x}\\mathcal{C}_{y}\\mathcal{C}_{z}$. First, we\nsolve the $\\mathcal{C}$-chiral symmetry constraint for eight band models and\ndescribe those induced by the partial $\\mathcal{C}_{i}$'s. Then, we determine\nthe explicit expression of fractional states characterising HOT matter and\ncomment on the relationships amongst them and with the standard\nAltland-Zirnbauer gapless modes. We also give characteristic properties of the\ngapless fractional states and compute their contribution to the topological\nindex of the chiral model. The findings of this work are shown to be crucial\nfor investigating and handling high order topological phase."
    },
    {
        "anchor": "Enhancement of bulk photovoltaic effect in topological insulators: We investigate the shift current bulk photovoltaic response of materials\nclose to a band inversion topological phase transition. We find that the bulk\nphotocurrent reverses direction across the band inversion transition, and that\nits magnitude is enhanced in the vicinity of the phase transition. These\nresults are demonstrated with first principles DFT calculations of BiTeI and\nCsPbI$_3$ under hydrostatic pressure, and explained with an analytical model,\nsuggesting that this phenomenon remains robust across disparate material\nsystems.",
        "positive": "Fluorination-Enriched Electronic and Magnetic Properties in Graphene\n  Nanoribbons: The feature-rich electronic and magnetic properties of fluorine-doped\ngraphene nanoribbons are investigated by the first-principles calculations.\nThey arise from the cooperative or competitive relations among the significant\nchemical bonds, finite-size quantum confinement and edge structure. There exist\nC-C, C-F, and F-F bonds with the multi-orbital hybridizations. Fluorine adatoms\ncan create the p-type metals or the concentration- and distribution-dependent\nsemiconductors, depending on whether the $\\pi$ bonding is seriously suppressed\nby the top-site chemical bonding. Furthermore, five kinds of spin-dependent\nelectronic and magnetic properties cover the non-magnetic and ferromagnetic\nmetals, the non-magnetic semiconductors, and the anti-ferromagnetic\nsemiconductors with/without the spin splitting. The diverse essential\nproperties are clearly revealed in the spatial charge distribution, the spin\ndensity, and the orbital-projected density of states."
    },
    {
        "anchor": "Friction of Water on Graphene and Hexagonal Boron Nitride from ab initio\n  Methods: Very Different Slippage Despite Very Similar Interface Structures: Friction is one of the main sources of dissipation at liquid water/solid\ninterfaces. Despite recent progress, a detailed understanding of water/solid\nfriction in connection with the structure and energetics of the solid surface\nis lacking. Here we show for the first time that \\textit{ab initio} molecular\ndynamics can be used to unravel the connection between the structure of\nnanoscale water and friction for liquid water in contact with graphene and with\nhexagonal boron nitride. We find that whilst the interface presents a very\nsimilar structure between the two sheets, the friction coefficient on boron\nnitride is $\\approx 3$ times larger than that on graphene. This comes about\nbecause of the greater corrugation of the energy landscape on boron nitride\narising from specific electronic structure effects. We discuss how a subtle\ndependence of the friction on the atomistic details of a surface, that is not\nrelated to its wetting properties, may have a significant impact on the\ntransport of water at the nanoscale, with implications for the development of\nmembranes for desalination and for osmotic power harvesting.",
        "positive": "Topological properties of quantum periodic Hamiltonians: We consider periodic quantum Hamiltonians on the torus phase space\n(Harper-like Hamiltonians). We calculate the topological Chern index which\ncharacterizes each spectral band in the generic case. This calculation is made\nby a semi-classical approach with use of quasi-modes. As a result, the Chern\nindex is equal to the homotopy of the path of these quasi-modes on phase space\nas the Floquet parameter (\\theta) of the band is varied. It is quite\ninteresting that the Chern indices, defined as topological quantum numbers, can\nbe expressed from simple properties of the classical trajectories."
    },
    {
        "anchor": "2D SNS junction with Rashba spin-orbit interaction: The effect of Rashba spin-orbital interaction upon supercurrent in S-2DEG-S\nproximity junctions is investigated in the clean limit. Generalization of\nBeenakker's formula for Andreev levels to the case of spin-orbital scattering\nis presented. Spin-orbit - induced splitting of Andreev bound-states is\npredicted for a junction of infinite width, and with non-vanishing normal\nbackscattering at S/N interfaces. Semiclassical average of the Josephson\ncurrent is however insensitive to the Rashba coupling as long as\nelectron-electron interaction in 2DEG is neglected.",
        "positive": "Non-conservation of the valley density and its implications for the\n  observation of the valley Hall effect: We show that the conservation of the valley density in multi-valley and\ntime-reversal-invariant insulators is broken in an unexpected way by the\nelectric field that drives the valley Hall effect. This implies that\nfully-gapped insulators can support a valley Hall current in the bulk and yet\nshow no valley density accumulation on the edges. Thus, the valley Hall effect\ncannot be observed in such systems. If the system is not fully gapped then\nvalley density accumulation at the edges is possible and can result in a net\ngeneration of valley density. The accumulation has no contribution from\nundergap states and can be expressed as a Fermi surface average, for which we\nderive an explicit formula. We demonstrate the theory by calculating the valley\ndensity accumulations in an archetypical valley-Hall insulator: a gapped\ngraphene nanoribbon. Surprisingly, we discover that a net valley density\npolarization is dynamically generated for some types of edge terminations."
    },
    {
        "anchor": "New fermions on the line in topological symmorphic metals: Topological metals and semimetals (TMs) have recently drawn significant\ninterest. These materials give rise to condensed matter realizations of many\nimportant concepts in high-energy physics, leading to wide-ranging protected\nproperties in transport and spectroscopic experiments. The most studied TMs,\ni.e., Weyl and Dirac semimetals, feature quasiparticles that are direct\nanalogues of the textbook elementary particles. Moreover, the TMs known so far\ncan be characterized based on the dimensionality of the band crossing. While\nWeyl and Dirac semimetals feature zero-dimensional points, the band crossing of\nnodal-line semimetals forms a one-dimensional closed loop. In this paper, we\nidentify a TM which breaks the above paradigms. Firstly, the TM features\ntriply-degenerate band crossing in a symmorphic lattice, hence realizing\nemergent fermionic quasiparticles not present in quantum field theory.\nSecondly, the band crossing is neither 0D nor 1D. Instead, it consists of two\nisolated triply-degenerate nodes interconnected by multi-segments of lines with\ntwo-fold degeneracy. We present materials candidates. We further show that\ntriplydegenerate band crossings in symmorphic crystals give rise to a Landau\nlevel spectrum distinct from the known TMs, suggesting novel magneto-transport\nresponses. Our results open the door for realizing new topological phenomena\nand fermions including transport anomalies and spectroscopic responses in\nmetallic crystals with nontrivial topology beyond the Weyl/Dirac paradigm.",
        "positive": "Nonlinear non-Hermitian higher-order topological laser: We investigate topological lasers in combination of nonlinear, non-Hermitian\nand topological lattice systems based on a quench dynamics starting from one\nsite. We consider explicitly the topological laser in the Su-Schrieffer-Heeger\n(SSH) model with two topological edge states and the second-order topological\nlaser in the breathing Kagome lattice with three topological corner states.\nOnce we stimulate any one site, after a delay, all sites belonging to the\ntopological edge or corner states begin to emit stable laser light depending on\nthe density of states, although no wave propagation is observed from the\nstimulated site. It is intriguing that the profile of topological edge or\ncorner states is observable by measuring the intensity of lasing. The\nphenomenon occurs due to a combinational effect of linear non-Hermitian loss\nterms and nonlinear non-Hermitian gain terms in the presence of the topological\nedge or corner states."
    },
    {
        "anchor": "On the electron transport in conducting polymer nanofibers: Recent advances in synthesis and electrical characterization of nanofibers\nand nanotubes made out of various conjugated polymers attract attention of the\nresearch community to studies of transport properties of these materials. In\nthis work we present a theoretical analysis of electron transport in polymer\nnanofibers assuming them to be in conducting state. We treat a conducting\npolymer as a network of metallic-like grains embedded in poorly conducting\nenvironment, which consists of randomly distributed polymeric chains. We\nanalyze the contribution from intergrain electron resonance tunneling via\nintermediate states localized on the polymeric chains between the grains.\nCorrespondingly, we apply the quantum theory of conduction in mesoscopic\nsystems to analyze this transport mechanism. We show that the contribution of\nresonance electron tunneling to the intergrain electron transport may be\npredominating, as follows from experiments on the electrical characterization\nof single polyaniline nanofibers. We study the effect of temperature on the\ntransport characteristics. We represent the thermal environment as a phonon\nbath coupled to the intermediate state, which provides electron tunneling\nbetween the metallic-like grains. Using the Buttiker model within the\nscattering matrix formalism combined with the nonequilibrium Green's functions\ntechnique, we show that temperature dependencies of both current and\nconductance associated with the intergrain electron tunneling, differ from\nthose typical for other conduction mechanisms in conducting polymers. Also, we\ndemonstrate that under certain conditions the phonon bath may cause suppression\nof the original intermediate state accompanied by emergence of new states for\nelectron tunneling. The temperature dependencies of the magnitudes of the peaks\nin the transmission corresponding to these new states are analyzed.",
        "positive": "Josephson radiation from gapless Andreev bound states in HgTe-based\n  topological junctions: Frequency analysis of the rf emission of oscillating Josephson supercurrent\nis a powerful passive way of probing properties of topological Josephson\njunctions. In particular, measurements of the Josephson emission enables to\ndetect the expected presence of topological gapless Andreev bound states that\ngive rise to emission at half the Josephson frequency $f_J$, rather than\nconventional emission at $f_J$. Here we report direct measurement of rf\nemission spectra on Josephson junctions made of HgTe-based gate-tunable\ntopological weak links. The emission spectra exhibit a clear signal at half the\nJosephson frequency $f_{\\rm J}/2$. The linewidths of emission lines indicate a\ncoherence time of $0.3-\\SI{4}{ns}$ for the $f_{\\rm J}/2$ line, much shorter\nthan for the $f_{\\rm J}$ line ($3-\\SI{4}{ns}$). These observations strongly\npoint towards the presence of topological gapless Andreev bound states, and\npave the way for a future HgTe-based platform for topological quantum\ncomputation."
    },
    {
        "anchor": "Acoustically regulated carrier injection into a single optically active\n  quantum dot: We study the carrier injection into a single InGaAs/GaAs quantum dot\nregulated by a radio frequency surface acoustic wave. We find that the time of\nlaser excitation during the acoustic cycle programs both the emission\nintensities and time of formation of neutral $(X^0)$ and negatively charged\n$(X^-)$ excitons. We identify underlying, characteristic formation pathways of\nboth few-particle states in the time-domain experiments and show that both\nexciton species can be formed either with the optical pump or at later times by\ninjection of single electrons and holes \"surfing\" the acoustic wave. All\nexperimental observations are in excellent agreement with calculated electron\nand hole trajectories in the plane of the two-dimensional wetting layer which\nis dynamically modulated by the acoustically induced piezoelectric potentials.\nTaken together, our findings provide insight on both the onset of\nacousto-electric transport of electrons and holes and their conversion into the\noptical domain after regulated injection into a single quantum dot emitter.",
        "positive": "Current-field diagram of magnetic states of a surface spin valve in a\n  point contact with a single ferromagnetic film: We present a study of the influence of an external magnetic field H and an\nelectric current I on the spin-valve (SV) effect between a ferromagnetic thin\nfilm (F) and a sharp tip of a nonmagnetic metal (N). To explain our\nobservations, we propose a model of a local surface SV which is formed in such\na N/F contact. In this model, a ferromagnetic cluster at the N/F interface\nplays the role of the free layer in this SV. This cluster exhibits a larger\ncoercive field than the bulk of the ferromagnetic film, presumably due to its\nnanoscale nature. Finally, we construct a magnetic state diagram of the surface\nSV as a function of I and H."
    },
    {
        "anchor": "Qubit-photon interactions in a cavity: Measurement induced dephasing and\n  number splitting: We theoretically study measurement induced-dephasing of a superconducting\nqubit in the circuit QED architecture and compare the results to those obtained\nexperimentally by Schuster {\\it et al.}, [Phys. Rev. Lett. 94, 123602 (2005)].\nStrong coupling of the qubit to the resonator leads to a significant ac-Stark\nshift of the qubit transition frequency. As a result, quantum fluctuations in\nthe photon number populating the resonator cause dephasing of the qubit. We\nfind good agreement between the predicted line shape of the qubit spectrum and\nthe experimental results. Furthermore, in the strong dispersive limit, where\nthe Stark shift per photon is large compared to the cavity decay rate and the\nqubit linewidth, we predict that the qubit spectrum will be split into multiple\npeaks, with each peak corresponding to a different number of photons in the\ncavity.",
        "positive": "Wigner crystallization at graphene edges: Using many-body configuration interaction techniques we show that Wigner\ncrystallization occurs at the zigzag edges of graphene at surprisingly high\nelectronic densities up to $0.8$ $\\mbox{nm}^{-1}$. In contrast with\none-dimensional electron gas, the flat-band structure of the edge states makes\nthe system interaction dominated, facilitating the electronic localization. The\nresulting Wigner crystal manifests itself in pair-correlation functions, and\nevolves smoothly as the edge electron density is lowered. We also show that the\ncrystallization affects the magnetization of the edges. While the edges are\nfully polarized when the system is charge neutral (i.e. high density), above\nthe critical density, the spin-spin correlations between neighboring electrons\ngo through a smooth transition from antiferromagnetic to magnetic coupling as\nthe electronic density is lowered."
    },
    {
        "anchor": "Metallic coatings of MEMS at low temperatures: stress, elasticity and\n  non-linear dissipation: We present mechanical measurements performed at low temperatures on\ncantilever-based microelectro-mechanicalstructures(MEMS) coated with a metallic\nlayer. Two very different coatings are presented in order to illustrate the\ncapabilities of the present approach, namely (soft) aluminum and (hard) niobium\noxide. The temperature is used as a control parameter to access materials\nproperties. We benefit from low temperature techniques to extract a\nphase-resolved measurement of the first mechanical resonance mode in cryogenic\nvacuum. By repeating the experiment on the same samples, after multiple\nmetallic depositions, we can determine accurately the contribution of the\ncoating layers to the mechanical properties in terms of surface stress,\nadditional mass, additional elasticity and damping. Analytic theoretical\nexpressions are derived and used to fit the data. Taking advantage of the\nextremely broad dynamic range provided by the technique, we can measure the\nanelasticity of the thin metallic film. The key parameters describing the\nmetals' dynamics are analyzed in an original way in order to provide new\nexperimental grounds for future theoretical modelings of the underlying\nmechanisms.",
        "positive": "Nanoassembly technique of carbon nanotubes for hybrid circuit-QED: A complex quantum dot circuit based on a clean and suspended carbon nanotube\nembedded in a circuit quantum electrodynamique (cQED) architecture is a very\nattractive platform to investigate a large spectrum of physics phenomena\nranging from qubit physics to nanomechanics. We demonstrate a carbon nanotube\ntransfer process allowing us to integrate clean carbon nanotubes into complex\nquantum dot circuits inside a cQED platform. This technique is compatible with\nvarious contacting materials such as superconductors or ferromagnets. This\nmakes it suitable for hybrid quantum devices. Our results are based on 8\ndifferent devices demonstrating the robustness of this technique."
    },
    {
        "anchor": "Anisotropic Laser-Pulse-Induced Magnetization Dynamics in van der Waals\n  Magnet Fe$_3$GeTe$_2$: Femtosecond laser-pulse excitation provides an energy efficient and fast way\nto control magnetization at the nanoscale, providing great potential for\nultrafast next-generation data manipulation and nonvolatile storage devices.\nFerromagnetic van der Waals materials have garnered much attention over the\npast few years due to their low dimensionality, excellent magnetic properties,\nand large response to external stimuli. Nonetheless, their behaviour upon fs\nlaser-pulse excitation remains largely unexplored. Here, we investigate the\nultrafast magnetization dynamics of a thin flake of Fe$_3$GeTe$_2$ (FGT) and\nextract its intrinsic magnetic properties using a microscopic framework. We\nfind that our data is well described by our modelling, with FGT undergoing a\nslow two-step demagnetization, and we experimentally extract the\nspin-relaxation timescale as a function of temperature, magnetic field and\nexcitation fluence. Our observations indicate a large spin-flip probability in\nagreement with a theoretically expected large spin-orbit coupling, as well as a\nweak interlayer exchange coupling. The spin-flip probability is found to\nincrease when the magnetization is pulled away from its quantization axis,\nopening doors to an external control over the spins in this material. Our\nresults provide a deeper understanding of the dynamics van der Waals materials\nupon fs laser-pulse excitation, paving the way towards two-dimensional\nmaterials-based ultrafast spintronics.",
        "positive": "Quantum oscillations in Weyl semimetals - a surface theory approach: We develop an effective surface theory for the surface states of a Weyl\nsemimetal. This theory includes the peculiar Fermi arc states on the surface as\nwell as leakage of the states from the surface to the bulk. Subjecting the\nmodel to a magnetic field perpendicular to the surface results in quantum\noscillations. The oscillations are different from the usual ones since they do\nnot involve a closed Fermi surface cross section. It has been shown previously\nthat the Quantum oscillations can be understood semiclassically as resulting\nfrom motion of electrons on the surface Fermi arcs as well as tunneling through\nchiral Landau levels associated with the bulk. In this work we develop an\neffective surface theory and use it to analyze the quantum oscillation in the\nsemiclassical regime and beyond. Specifically, we show that when a pair of Weyl\npoints are close to each other the surface quantum oscillations acquire a phase\noffset which originates from the bulk. While the surface states are responsible\nfor a large part of the electron motion, tunneling through the bulk is\nnecessary for completing the orbit. This tunneling makes use of the bulk, zero\nenergy, chiral Landau level in each Weyl node. When the nodes are close in\nmomentum space their chiral levels overlap and a gap at zero energy is formed.\nThis gap causes the phase offset in the surface quantum oscillations."
    },
    {
        "anchor": "Length scale of puddle formation in compensation-doped semiconductors\n  and topological insulators: In most semiconductors and insulators the presence of a small density of\ncharged impurities cannot be avoided, but their effect can be reduced by\ncompensation doping, i.e. by introducing defects of opposite charge. Screening\nin such a system leads to the formation of electron-hole puddles, which\ndominate bulk transport, as first recognized by Efros and Shklovskii. Metallic\nsurface states of topological insulators (TI) contribute extra screening\nchannels, suppressing puddles. We investigate the typical length $l_p$, which\ndetermines the distance between puddles and the suppression of puddle formation\nclose to metallic surfaces in the limit where the gap $\\Delta$ is much larger\nthan the typical Coulomb energy $E_c$ of neighboring dopants, $\\Delta \\gg E_c$.\nIn particular, this is relevant for three dimensional Bi-based topological\ninsulators, where $\\Delta/E_c \\sim 100$. Scaling arguments predict $l_p \\sim\n(\\Delta/E_c)^2$. In contrast, we find numerically that $l_p$ is much smaller\nand grows in an extended crossover regime approximately linearly with\n$\\Delta/E_c$ for numerically accessible values, $\\Delta/E_c \\lesssim 35$. We\nshow how a quantitative scaling argument can be used to extrapolate to larger\n$\\Delta/E_c$, where $l_p \\sim (\\Delta/E_c)^2/\\ln(\\Delta/E_c)$. Our results can\nbe used to predict a characteristic thickness of TI thin films, below which the\nsample quality is strongly enhanced.",
        "positive": "Robust magnetotransport in disordered ferromagnetic kagome layers with\n  quantum anomalous Hall effect: The magnetotransport properties of disordered ferromagnetic kagome layers are\ninvestigated numerically. We show that a large domain-wall magnetoresistance or\nnegative magnetoresistance can be realized in kagome layered materials (e.g.\nFe$_3$Sn$_2$, Co$_3$Sn$_2$S$_2$, and Mn$_3$Sn), which show the quantum\nanomalous Hall effect. The kagome layers show a strong magnetic anisotropy and\na large magnetoresistance depending on their magnetic texture. These\ndomain-wall magnetoresistances are expected to be robust against disorder and\nobserved irrespective of the domain-wall thickness, in contrast to conventional\ndomain-wall magnetoresistance in ferromagnetic metals."
    },
    {
        "anchor": "Loss Mechanism Analyses of Perovskite Solar Cells with an Equivalent\n  Circuit Model: Understanding and quantifying the main loss factors affecting the power\nconversion efficiency of perovskite solar cells are urgently needed. In this\nwork, based on semiconductor physics, the expressions of bulk and surface\nrecombination currents are analytically derived. Then taking the optical loss,\nseries and shunt resistance losses, and bulk and surface recombination losses\ninto consideration, an equivalent circuit model is proposed to describe the\ncurrent density-voltage characteristics of practical perovskite solar cells.\nFurthermore, by comparing to the drift-diffusion model, the pre-defined\nphysical parameters of the drift-diffusion model well agree with the fitting\nparameters retrieved by the equivalent circuit model, which verifies the\nreliability of the proposed model. Moreover, when the circuit model is applied\nto analyze experimental results, the fitting outcomes show favorable\nconsistency to the physical investigations offered by the experiments. And the\nrelative fitting errors of the above cases are all less than 2%. Through\nemploying the model, the dominant recombination type is clearly identified and\nsplit current density-voltage curves characterizing different loss mechanisms\nare offered, which intuitively reveals the physical principles of efficiency\nloss. Additionally, through calculating the efficiency loss ratios under the\nopen-circuit voltage condition, quantifying the above-mentioned loss mechanisms\nbecomes simple and compelling. Consequently, this model offers a guideline to\napproach the efficiency limit from a circuit-level perspective. And the model\nis a comprehensive simulation and analysis tool for understanding the device\nphysics of perovskite solar cells.",
        "positive": "Controlled single electron transfer between Si:P dots: We demonstrate electrical control of Si:P double dots in which the potential\nis defined by nanoscale phosphorus doped regions. Each dot contains\napproximately 600 phosphorus atoms and has a diameter close to 30 nm. On\napplication of a differential bias across the dots, electron transfer is\nobserved, using single electron transistors in both dc- and rf-mode as charge\ndetectors. With the possibility to scale the dots down to few and even single\natoms these results open the way to a new class of precision-doped quantum dots\nin silicon."
    },
    {
        "anchor": "Localization of Dirac-like excitations in graphene in the presence of\n  smooth inhomogeneous magnetic fields: The present article discusses magnetic confinement of the Dirac excitations\nin graphene in presence of inhomogeneous magnetic fields. In the first case a\nmagnetic field directed along the z axis whose magnitude is proportional to\n$1/r$ is chosen. In the next case we choose a more realistic magnetic field\nwhich does not blow up at the origin and gradually fades away from the origin.\nThe magnetic fields chosen do not have any finite/infinite discontinuity for\nfinite values of the radial coordinate. The novelty of the two magnetic fields\nis related to the equations which are used to find the excited spectra of the\nexcitations. It turns out that the bound state solutions of the two-dimensional\nhydrogen atom problem are related to the spectra of graphene excitations in\npresence of the $1/r$ (inverse-radial) magnetic field. For the other magnetic\nfield profile one can use the knowledge of the bound state spectrum of a\ntwo-dimensional cut-off Coulomb potential to dictate the excitation spectra of\nthe states of graphene. The spectrum of the graphene excitations in presence of\nthe inverse-radial magnetic field can be exactly solved while the other case\ncannot be. In the later case we give the localized solutions of the zero-energy\nstates in graphene.",
        "positive": "Strong non-equilibrium effects in spin torque systems: We consider a problem of persistent magnetization precession in a single\ndomain ferromagnetic nano particle under the driving by the spin-transfer\ntorque. We find that the adjustment of the electronic distribution function in\nthe particle renders this state unstable. Instead, abrupt switching of the spin\norientation is predicted upon increase of the spin-transfer torque current. On\nthe technical level, we derive an effective action of the type of\nAmbegaokar-Eckern-Sch\\\"on action for the coupled dynamics of magnetization\n(gauge group $SU(2)$) and voltage (gauge group $U(1)$)."
    },
    {
        "anchor": "Axial Current driven by Magnetization Dynamics in Weyl Semimetals: We theoretically study the axial current $\\bm{j}_5$ (defined as the\ndifference between the charge current with opposite chirality) in doped Weyl\nsemimetal using a Green's function technique. We show that the axial current is\ncontrolled by the magnetization dynamics in a magnetic insulator attached to a\nWeyl semimetal. We find that the induced axial current can be detected by using\nferromagnetic resonance or the inverse spin Hall effect and can be converted\ninto charge current with no accompanying energy loss. These properties make\nWeyl semimetal advantageous for application to low-consumption electronics with\nnew functionality.",
        "positive": "Quantum transport signature of strain-induced scalar and pseudo-vector\n  potentials in a crenellated hBN-graphene heterostructure: The sharp Dirac cone of the electronic dispersion confers to graphene a\nremarkable sensitivity to strain. It is usually encoded in scalar and\npseudo-vector potentials, induced by the modification of hopping parameters,\nwhich have given rise to new phenomena at the nanoscale such as giant\npseudomagnetic fields and valley polarization. Here, we unveil the effect of\nthese potentials on the quantum transport across a succession of strain-induced\nbarriers. We use high-mobility, hBN-encapsulated graphene, transferred over a\nlarge (10x10 $\\mu$m$^{2}$) crenellated hBN substrate. We show the emergence of\na broad resistance ancillary peak at positive energy that arises from Klein\ntunneling barriers induced by the tensile strain at the trench edges. Our\ntheoretical study, in quantitative agreement with experiment, highlights the\nbalanced contributions of strain-induced scalar and pseudo-vector potentials on\nballistic transport. Our results establish crenellated van der Waals\nheterostructures as a promising platform for strain engineering in view of\napplications and basic physics."
    },
    {
        "anchor": "Spin textures of strongly correlated spin Hall quantum dots: We study the spin ordering of a quantum dot defined via magnetic barriers in\nan interacting quantum spin Hall edge. The spin-resolved density-density\ncorrelation functions are computed. We show that strong electron interactions\ninduce a ground state with a highly correlated spin pattern. The crossover from\nthe liquid-type correlations at weak interactions to the ground state spin\ntexture found at strong interactions parallels the formation of a\none-dimensional Wigner molecule in an ordinary strongly interacting quantum\ndot.",
        "positive": "Dynamics of interacting transport qubits: We investigate the electronic transport through two parallel double quantum\ndots coupled both capacitively and via a perpendicularly aligned charge qubit.\nThe presence of the qubit leads to a modification of the coherent tunnel\namplitudes of each double quantum dot. We study the influence of the qubit on\nthe electronic steady state currents through the system, the entanglement\nbetween the transport double quantum dots, and the back action on the charge\nqubit. We use a Born-Markov-Secular quantum master equation for the system. The\nobtained currents show signatures of the qubit. The stationary qubit state may\nbe tuned and even rendered pure by applying suitable voltages. In the Coulomb\ndiamonds it is also possible to stabilize pure entangled states of the\ntransport double quantum dots."
    },
    {
        "anchor": "Friedel Sum Rule for single channel quantum wire: Elastic scattering in a quantum wire has several novel features not seen in\n1D, 2D or 3D. In this work we consider a single channel quantum wire as its\napplication is inevitable in making devices based on quantum interference\neffects. We consider a point defect or a single delta function impurity in such\na wire and show how some of these novel features affect Friedel-sum-rule (FSR)\nin a way, that is quite unlike in 1D, 2D and 3D.",
        "positive": "Response of parametrically-driven nonlinear coupled oscillators with\n  application to micro- and nanomechanical resonator arrays: The response of a coupled array of nonlinear oscillators to parametric\nexcitation is calculated in the weak nonlinear limit using secular perturbation\ntheory. Exact results for small arrays of oscillators are used to guide the\nanalysis of the numerical integration of the model equations of motion for\nlarge arrays. The results provide a qualitative explanation for a recent\nexperiment [Buks and Roukes, cond-mat/0008211, to appear in J. MEMS (2002)]\ninvolving a parametrically-excited micromechanical resonator array. Future\nexperiments are suggested that could provide quantitative tests of the\ntheoretical predictions."
    },
    {
        "anchor": "Hartree theory calculations of quasiparticle properties in twisted\n  bilayer graphene: A detailed understanding of interacting electrons in twisted bilayer graphene\n(tBLG) near the magic angle is required to gain insights into the physical\norigin of the observed broken symmetry phases. Here, we present extensive\natomistic Hartree theory calculations of the electronic properties of tBLG in\nthe (semi-)metallic phase as function of doping and twist angle. Specifically,\nwe calculate quasiparticle properties, such as the band structure, density of\nstates (DOS) and local density of states (LDOS), which are directly accessible\nin photoemission and tunnelling spectroscopy experiments. We find that\nquasiparticle properties change significantly upon doping - an effect which is\nnot captured by tight-binding theory. In particular, we observe that the\npartially occupied bands flatten significantly which enhances the density of\nstates at the Fermi level. We predict a clear signature of this band flattening\nin the LDOS in the AB/BA regions of tBLG which can be tested in scanning\ntunneling experiments. We also study the dependence of quasiparticle properties\non the dielectric environment of tBLG and discover that these properties are\nsurprisingly robust as a consequence of the strong internal screening. Finally,\nwe present a simple analytical expression for the Hartree potential which\nenables the determination of quasiparticle properties without the need for\nself-consistent calculations.",
        "positive": "Theory of the Magnon Parametron: The 'magnon parametron' is a ferromagnetic particle that is parametrically\nexcited by microwaves in a cavity. Above a certain threshold of the microwave\npower, a bistable steady state emerges that forms an effective Ising spin. We\ncalculate the dynamics of the magnon parametron as a function of microwave\npower, applied magnetic field and temperature for the interacting magnon\nsystem, taking into account thermal and quantum fluctuations. We predict three\ndynamical phases, viz. a stable Ising spin, telegraph noise of thermally\nactivated switching, and an intermediate regime that at lower temperatures is\nquantum correlated with significant distillible magnon entanglement. These\nthree regimes of operation are attractive for alternative computing schemes."
    },
    {
        "anchor": "Observation of non-Hermitian many-body skin effects in Hilbert space: Non-Hermiticity greatly expands existing physical laws beyond the Hermitian\nframework, revealing various novel phenomena with unique properties. Up to now,\nmost exotic nonHermitian effects, such as exceptional points and non-Hermitian\nskin effects, are discovered in single-particle systems. The interplay between\nnon-Hermitian and manybody correlation is expected to be a more fascinating but\nmuch less explored area. Due to the complexity of the problem, current\nresearches in this field mainly stay at the theoretical level. The experimental\nobservation of predicted non-Hermitian manybody phases is still a great\nchallenging. Here, we report the first experimental simulation of strongly\ncorrelated non-Hermitian many-body system, and reveal a new type of\nnonHermitian many-body skin states toward effective boundaries in Hilbert\nspace. Such an interaction-induced non-Hermitian many-body skin effect\nrepresents the aggregation of bosonic clusters with non-identical occupations\nin the periodic lattice. In particular, by mapping eigen-states of three\ncorrelated bosons to modes of the designed threedimensional electric circuit,\nnon-Hermitian many-body skin effects in Hilbert space is verified by measuring\nthe spatial impedance response. Our finding not only discloses a new physical\neffect in the non-Hermitian many-body system, but also suggests a flexible\nplatform to further investigate other non-Hermitian correlated phases in\nexperiments.",
        "positive": "Topological magnons in CrI$_3$ monolayers: an itinerant fermion\n  description: Magnons dominate the magnetic response of the recently discovered insulating\nferromagnetic two dimensional crystals such as CrI$_3$. Because of the\narrangement of the Cr spins in a honeycomb lattice, magnons in CrI$_3$ bear a\nstrong resemblance with electronic quasiparticles in graphene. Neutron\nscattering experiments carried out in bulk CrI$_3$ show the existence of a gap\nat the Dirac points, that has been conjectured to have a topological nature.\nHere we propose a theory for magnons in ferromagnetic CrI$_3$ monolayers based\non an itinerant fermion picture, with a Hamiltonian derived from first\nprinciples. We obtain the magnon dispersion for 2D CrI$_3$ with a gap at the\nDirac points with the same Berry curvature in both valleys. For CrI$_3$\nribbons, we find chiral in-gap edge states. Analysis of the magnon wave\nfunctions in momentum space further confirms their topological nature.\nImportantly, our approach does not require to define a spin Hamiltonian, and\ncan be applied to both insulating and conducting 2D materials with any type of\nmagnetic order."
    },
    {
        "anchor": "Ratchet transport of a two-dimensional electron gas at cyclotron\n  resonance: The driving of charge carriers confined in a quantum well lacking the center\nof space inversion by an alternating electric field leads to the formation of a\ndirect electric current. We develop a microscopic theory of such a quantum\nratchet effect for quantum wells subjected to a static magnetic field. We show\nthat the ratchet current emerges for a linearly polarized alternating electric\nfield as well as a rotating electric field and drastically increases at the\ncyclotron resonance conditions. For the magnetic field tilted with respect to\nthe quantum well normal, the ratchet current contains an additional resonance\nat the first subharmonic of the cyclotron resonance.",
        "positive": "Cross-correlations of coherent multiple Andreev reflections: We use the Landauer-B\\\"uttiker scattering theory for electronic transport to\ncalculate the current cross-correlations in a voltage-biased three-terminal\njunction with all superconducting leads. At low bias voltage, when charge\ntransport is due to coherent multiple Andreev reflections, we find large\ncross-correlations compared with their normal-state value. Furthermore,\ndepending on the parameters that characterize the properties of the scattering\nregion between the leads, the cross-correlations can reverse their sign with\nrespect to the case of non-interacting fermionic systems."
    },
    {
        "anchor": "Mott-Hubbard Transition of Bosons in Optical Lattices with Three-body\n  Interactions: In this paper, the quantum phase transition between superfluid state and\nMott-insulator state is studied based on an extended Bose-Hubbard model with\ntwo- and three-body on-site interactions. By employing the mean-field\napproximation we find the extension of the insulating 'lobes' and the existence\nof a fixed point in three dimensional phase space. We investigate the link\nbetween experimental parameters and theoretical variables. The possibility to\nobverse our results through some experimental effects in optically trapped\nBose-Einstein Condensates(BEC) is also discussed.",
        "positive": "Optical Dichroism by Nonlinear Excitations in Graphene Nanoribbons: The honeycomb carbon structure of graphene and nanotubes has a dynamics which\ncan give rise to a spectrum. This can be excited via the interaction with an\nexternal electromagnetic field. In this work, non-linear waves on graphene and\nnanotubes associated with the carbon structure are investigated using a gauge\nmodel. Typical energies are estimated and there scaling with the nanoribbon\nwidth investigated. Furthermore, the soliton-photon interaction depends on the\nincident photon polarization. In particular, we find that the nanoribbon is\ntransparent when the polarization is along the largest length. Relying on the\nscaling with the width, we suggest a way to experimentally identify the soliton\nwaves in nanoribbons."
    },
    {
        "anchor": "Nonlocal Response of Polar Nanostructures: Polar dielectric nanoresonators can support hybrid photon-phonon modes termed\nsurface phonon polaritons with lengthscales below the diffraction limit. In the\ndeep sub-wavelength regime the optical response of these systems was recently\nshown to diverge from that predicted through a standard dielectric description.\nRecently we developed an analytical, dielectric approach and applied it to\nspheres and planar heterostructures, reproducing anomalous features observed in\nexperiment and microscopic calculations. In this Letter we develop tools to\ndescribe the nonlocal response of polar nanoresonators of arbitrary symmetry.\nTheir validity is verified by comparison to our previous analytical work,\nbefore application to new systems. We show that nonlocal energy transfer into\nmatter-like modes in the dielectric diminish field enhancement in nanoscale\ndimers and that strong nonlocal frequency shifts are possible in macroscopic\nsystems comprised of nanoscopic layers.",
        "positive": "Liquid exfoliation of solvent-stabilised black phosphorus: applications\n  beyond electronics: Few layer black phosphorus is a new two-dimensional material which is of\ngreat interest for applications, mainly in electronics. However, its lack of\nstability severely limits our ability to synthesise and process this material.\nHere we demonstrate that high-quality, few-layer black phosphorus nanosheets\ncan be produced in large quantities by liquid phase exfoliation in the solvent\nN-cyclohexyl-2-pyrrolidone (CHP). We can control nanosheet dimensions and have\ndeveloped metrics to estimate both nanosheet size and thickness\nspectroscopically. When exfoliated in CHP, the nanosheets are remarkably stable\nunless water is intentionally introduced. Computational studies show the\ndegradation to occur by reaction with water molecules only at the nanosheet\nedge, leading to the removal of phosphorus atoms and the formation of phosphine\nand phosphorous acid. We demonstrate that liquid exfoliated black phosphorus\nnanosheets are potentially useful in a range of applications from optical\nswitches to gas sensors to fillers for composite reinforcement."
    },
    {
        "anchor": "Circular-polarization sensitive metamaterial based on triple quantum-dot\n  molecules: We propose a new type of a chiral metamaterial based on an ensemble of\nartificial molecules formed by three identical quantum-dots in a triangular\narrangement. A static magnetic field oriented perpendicular to the plane breaks\nmirror symmetry, rendering the molecules sensitive to the circular polarization\nof light. By varying the orientation and magnitude of the magnetic field one\ncan control the polarization and frequency of the emission spectrum. We\nidentify a threshold frequency, {\\Omega}, above which we find strong\nbirefringence. In addition, a Kerr rotation and circularly polarized lasing\naction can be implemented. We investigate the single-molecule lasing properties\nfor different energy-level arrangements and demonstrate the possibility of\ncircular polarization conversion. Finally, we analyze the effect of weak stray\nelectric fields or deviations from the equilateral triangular geometry.",
        "positive": "Transmission in double quantum dots in the Kondo regime:\n  Quantum-critical transitions and interference effects: We study the transmission through a double quantum-dot system in the Kondo\nregime. An exact expression for the transmission coefficient in terms of fully\ninteracting many-body Green's functions is obtained. By mapping the system into\nan effective Anderson impurity model, one can determine the transmission using\nnumerical renormalization-group methods. The transmission exhibits signatures\nof the different Kondo regimes of the effective model, including an unusual\nKondo phase with split peaks in the spectral function, as well as a\npseudogapped regime exhibiting a quantum critical transition between Kondo and\nunscreened phases."
    },
    {
        "anchor": "Nanoladder cantilevers made from diamond and silicon: We present a \"nanoladder\" geometry that minimizes the mechanical dissipation\nof ultrasensitive cantilevers. A nanoladder cantilever consists of a\nlithographically patterned scaffold of rails and rungs with feature size $\\sim$\n100 nm. Compared to a rectangular beam of the same dimensions, the mass and\nspring constant of a nanoladder are each reduced by roughly two orders of\nmagnitude. We demonstrate a low force noise of $158 (+62)(-42)\\,$zN and $190\n(+42)(-33)\\,$zN in a one-Hz bandwidth for devices made from silicon and\ndiamond, respectively, measured at temperatures between 100--150 mK. As opposed\nto bottom-up mechanical resonators like nanowires or nanotubes, nanoladder\ncantilevers can be batch-fabricated using standard lithography, which is a\ncritical factor for applications in scanning force microscopy.",
        "positive": "Coupling a single electron spin to a microwave resonator: Controlling\n  transverse and longitudinal couplings: Microwave-frequency superconducting resonators are ideally suited to perform\ndispersive qubit readout, to mediate two-qubit gates, and to shuttle states\nbetween distant quantum systems. A prerequisite for these applications is a\nstrong qubit-resonator coupling. Strong coupling between an electron-spin qubit\nand a microwave resonator can be achieved by correlating spin- and orbital\ndegrees of freedom. This correlation can be achieved through the Zeeman\ncoupling of a single electron in a double quantum dot to a spatially\ninhomogeneous magnetic field generated by a nearby nanomagnet. In this paper,\nwe consider such a device and estimate spin-resonator couplings of order ~ 1\nMHz with realistic parameters. Further, through realistic simulations, we show\nthat precise placement of the double dot relative to the nanomagnet allows to\nselect between a purely longitudinal coupling (commuting with the bare spin\nHamiltonian) and a purely transverse (spin non-conserving) coupling.\nAdditionally, we suggest methods to mitigate dephasing and relaxation channels\nthat are introduced in this coupling scheme. This analysis gives a clear route\ntoward the realization of coherent state transfer between a microwave resonator\nand a single electron spin in a GaAs double quantum dot with a fidelity above\n90%. Improved dynamical decoupling sequences, low-noise environments, and\nlonger-lived microwave cavity modes may lead to substantially higher fidelities\nin the near future."
    },
    {
        "anchor": "Direct observation of spin-polarized surface states in the parent\n  compound of topological insulator Bi-Sb using spin-resolved-ARPES in a 3D\n  Mott-polarimetry spin mode: We report high-resolution spin-resolved photoemission spectroscopy\n(Spin-ARPES) measurements on the parent compound Sb of the first discovered 3D\ntopological insulator Bi{1-x}Sb{x} [D. Hsieh et al., Nature 452, 970 (2008)\nSubmitted 2007]. By modulating the incident photon energy, we are able to map\nboth the bulk and (111) surface band structure, from which we directly\ndemonstrate that the surface bands are spin polarized by the spin-orbit\ninteraction and connect the bulk valence and conduction bands in a\ntopologically non-trivial way. A unique asymmetric Dirac surface state gives\nrise to a $k$-splitting of its spin polarized electronic channels. These\nresults complement our previously published works on this materials class and\nre-confirm our discovery of first bulk (3D) topological insulator - topological\norder in bulk solids. [Invited article for NJP-IOP Focus issue on \"Topological\nInsulators\"]",
        "positive": "HFinFET: A Scalable, High Performance, Low Leakage Hybrid N-Channel FET: In this letter we propose the design and simulation study of a novel\ntransistor, called HFinFET, which is a hybrid of a HEMT and a FinFET, to obtain\nexcellent performance and good off state control. Followed by the description\nof the design, 3D device simulation has been performed to predict the\ncharacteristics of the device. The device has been benchmarked against\npublished state of the art HEMT as well as planar and non-planar Si NMOSFET\ndata of comparable gate length using standard benchmarking techniques."
    },
    {
        "anchor": "Next steps of quantum transport in Majorana nanowire devices: Majorana zero modes are localized quasiparticles that obey non-Abelian\nexchange statistics. Braiding Majorana zero modes forms the basis of\ntopologically protected quantum operations which could in principle\nsignificantly reduce qubit decoherence and gate control errors in the device\nlevel. Therefore, searching for Majorana zero modes in various solid state\nsystems is a major topic in condensed matter physics and quantum computer\nscience. Since the first experimental signature observed in hybrid\nsuperconductor-semiconductor nanowire devices, this field has witnessed a\ndramatic expansion in material science, transport experiments and theory. While\nmaking the first topological qubit based on these Majorana nanowires is\ncurrently an on-going effort, several related important transport experiments\nare still being pursued in the near term. These will not only serve as\nintermediate steps but also show Majorana physics in a more fundamental aspect.\nIn this perspective, we summarize these key Majorana experiments and the\npotential challenges.",
        "positive": "Kondo effect and bistability in a double-quantum-dot: We study theoretically the out-of-equilibrium transport properties of a\ndouble quantum dot system in the Kondo regime. We model the system by means of\na two-impurity Anderson Hamiltonian. The transport properties are characterized\nby Kondo effect properties, however, superimposed them, the system possesses\nnovel non-linear bistability behavior."
    },
    {
        "anchor": "Identification of different silicon vacancy centers in 6H-SiC: Silicon vacancies in silicon carbide (SiC) have been proposed as interesting\ncandidates for quantum technology applications such as quantum sensing and\nquantum repeaters. SiC exists in many polytypes with different plane stacking\nsequences, and in each polytype, the vacancies can occupy a variety of\ndifferent lattice sites. In this work, we characterize and identify the three\nmost important charged silicon vacancies in the 6H-SiC polytype. We record the\nphotoluminescence and continuous-wave optically detected magnetic resonance\nspectra at different radio-frequency power levels and different temperatures.\nWe individually select the zero-phonon lines of the different silicon vacancies\nat low temperatures and record the corresponding optically detected magnetic\nresonance (ODMR) spectra. ODMR allows us to correlate optical and magnetic\nresonance spectra and thereby resolve a controversy from earlier work.",
        "positive": "Unconventional optical selection rules in ZrTe5 under an in-plane\n  magnetic field: The optical selection rules of an electron system under a magnetic field play\nkey roles in determining its optical properties, from which the band structures\nand underlying symmetries can be derived. In this Letter, based on a\nthree-dimensional strong topological insulator model describing ZrTe5,we study\nthe Landau levels (LLs) and magneto-optical conductivity under an in-plane\nmagnetic field. We reveal that in the transverse conductivity Re(\\sigma_{zz}),\nthe unconventional optical selection rules n\\righatarrow n\\pm 2 dominate, with\nn being the LL index. We attribute the unconventional selection rules to the\npeculiar distribution of parity carried by the LLs, resulting from the chiral\nsymmetry of the sub-Hamiltonians. Moreover, we predict that, if the strong\nanisotropic system is tuned to be nearly isotropic, the LLs would redistribute\nand the conventional selection rules n\\rightarrow n\\pm 1 can be recovered."
    },
    {
        "anchor": "DC SQUID based on the mesoscopic multiterminal Josephson junction: A theory is offered for a novel device, mesoscopic four-terminal SQUID. The\nstudied system consists of a mesoscopic four-terminal junction, one pair of\nterminals of which is incorporated in a superconducting ring and the other one\nis connected with a transport circuit. The nonlocal weak coupling between the\nterminals leads to effects of phase dragging and magnetic flux transfer. The\nbehaviour of a four-terminal SQUID, controlled by the external parameters, the\napplied magnetic flux and the transport current is investigated. The critical\ncurrent and the current voltage characteristics as functions of magnetic flux\nare calculated. In the nonlocal mesoscopic case they depend not only on the\nmagnitude of the applied flux but also on its sign, allowing measurement of the\ndirection of the external magnetic field.",
        "positive": "Photo-Physical Characteristics of Boron Vacancy-Derived Defect Centers\n  in Hexagonal Boron Nitride: Single photon emitter (SPE) sources are important building blocks for\nphotonics-based quantum technologies. Recently, the highly bright and versatile\nSPEs from the two-dimensional insulator material hexagonal boron nitride (hBN)\nhave attracted significant research interest. However, due to the variability\nof emitter species and properties, an exact correlation between the underlying\natomistic structures and their photo-physical properties is still lacking. In\nthis work, we study six boron vacancy-derived defect centers in hBN ($V_B^-$,\n$V_B$+$H$, $V_{B2}$, $V_BC_N$, $V_BC_N^-$, and $V_BC_NC_N$) using advanced\nfirst principles techniques, characterizing their quasiparticle defect levels,\noptical spectra and excitation energies, and magneto-resonance properties.\nThese defects have been chosen because of their relatively low formation\nenergies, and, importantly, because they are amenable to intentional creation\nunder experimental conditions. We establish the correlation between the\nunderlying defect atomic structure and their photo-physical properties, thus\nfacilitating the identification of SPEs that have already been observed in\nexperiments. Our results lead to clear insights into very recent experiments\nwhere hBN SPEs can be controlled intentionally. On the other hand, our results\nalso serve as guidelines for the bottom-up design of defect emitter centers in\nhBN for target applications that require specific defect properties, such as\nemission in the telecom wavelength, optical addressability and high radiative\ndecay rates. This work thus provides a comprehensive understanding of the\nphoto-physical characteristics of $V_B$-derived defect emitting centers, aiding\nin their identification and manipulation for tailored applications."
    },
    {
        "anchor": "Spin accumulation in asymmetric topological insulator thin films in out\n  of plane magnetic fields: In this work we study the spin accumulation due to an in-plane electric field\nin an asymmetric topological insulator (TI) thin film system with an out of\nplane magnetic field and an in-plane magnetization. A TI thin film differs from\nthe more typically studied thick TI system in that the former has both a top\nand a bottom surface where the states localized at both surfaces can couple to\neach other due to the finite thickness. In typical spin torque experiments on\nTI thin film systems, the top and bottom surfaces of the film are asymmetric as\nthe former is in contact with a ferromagnetic layer while the latter is\nadjacent to a non magnetic substrate. This may lead to differing (i) potentials\nand (ii) magnetization strengths experienced by the top and bottom surface\nstates. We show, via Kubo formula calculations, that each of these two effects\ncan lead to in-plane spin accumulation perpendicular to the magnetization\ndirection which are otherwise absent in a top-bottom symmetric TI thin film\nsystem. This spin accumulation results from the breaking of the antisymmetry of\nthe spin accumulation around the zero magnetic field equal energy contours.",
        "positive": "3D nanostructuring of La0.7Sr0.3MnO3 thin film surfaces by scanning\n  tunnelling microscopy: Nanoscale 3D surface modifications, by scanning tunneling microscopy under\nambient conditions, of La0.7Sr0.3MnO3 thin films have been performed. It was\ndemonstrated that there are well defined combinations of bias voltages and scan\nspeeds which allow for controlled surface structuring. Lateral structures with\nsizes down to 1.5 nm are possible to obtain. Moreover, it is possible to\nreproducibly control the depth of etching with half a unit cell precision,\nenabling design of 3D surface structures and control of the surface termination\nof La0.7Sr0.3MnO3 through etching."
    },
    {
        "anchor": "Quasi-free-standing monolayer hexagonal boron nitride on Ni: The electronic structure of monolayer hexagonal boron nitride grown on Ni by\nthe diffusion and precipitation method was studied by x-ray absorption\nspectroscopy, emission spectroscopy, x-ray photoelectron spectroscopy and\nmicro-ultraviolet photoemission spectroscopy. No indication of hybridization\nbetween h-BN pi and Ni 3d orbitals was observed. That is, the monolayer h-BN\nwas found to be in the quasi-free-standing state. These results are in striking\ncontrast to those of previous studies in which h-BN was strongly bound to the\nNi surface by the orbital hybridization. The absence of hybridization is\nattributed to absence of a Ni(111) surface in this study. The lattice-matched\nNi(111) surface is considered to be essential to orbital hybridization between\nh-BN and Ni.",
        "positive": "Unusual change in the Dirac-cone energy band upon two-step magnetic\n  transition in CeBi: We have performed angle-resolved photoemission spectroscopy (ARPES) on CeBi\nwhich undergoes a two-step antiferromagnetic (AF) transition with temperature.\nSoft-x-ray ARPES has revealed the inverted band structure at the X point of\nbulk Brillouin zone for CeBi (and also for LaBi) as opposed to LaSb with\nnon-inverted band structure. Low-energy ARPES on CeBi has revealed the\nDirac-cone band at the Gamma point in the paramagnetic phase associated with\nthe bulk band inversion. On the other hand, a double Dirac-cone band appears on\nentering the first AF phase at T = 25 K, whereas a single Dirac-cone band\nrecovers below the second AF transition at T = 14 K. The present result\nsuggests an intricate interplay between antiferromagnetism and topological\nsurface states in CeBi."
    },
    {
        "anchor": "Correlated photon-pair emission from pumped-pulsed quantum dots embedded\n  in a microcavity: We theoretically investigate the optical response of a quantum dot, embedded\nin a microcavity and incoherently excited by pulsed pumping. The exciton and\nbiexciton transition are off-resonantly coupled with the left- and\nright-polarized mode of the cavity, while the two-photon resonance condition is\nfulfilled. Rich behaviours are shown to occur in the time dependence of the\nsecond-order correlation functions which refer to counter-polarized photons.\nThe corresponding time-averaged quantities, which are accessible to\nexperiments, confirm that such a dot-cavity system behaves as a good emitter of\nsingle, polarization-correlated photon pairs.",
        "positive": "Theory of pump-probe photoemission in graphene: Ultrafast tuning of\n  Floquet bands and local pseudospin textures: The control of physical properties of solids with short laser pulses is an\nintriguing prospect of ultrafast materials science. Continuous-wave\nhigh-frequency laser driving with circular polarization was predicted to induce\na light-matter coupled new state possessing a quasi-static band structure with\nan energy gap and a quantum Hall effect, coined \"Floquet topological\ninsulator\". Whereas the envisioned Floquet topological insulator requires well\nseparated Floquet bands and therefore high-frequency pumping, a natural\nfollow-up question regards the creation of Floquet-like states in graphene with\nrealistic pump laser pulses. Here we predict that with short low-frequency\nlaser pulses attainable in pump-probe experiments, states with local spectral\ngaps at the Dirac points and novel pseudospin textures can be achieved in\ngraphene using circular light polarization. We demonstrate that time- and\nangle-resolved photoemission spectroscopy can track these states by measuring\nsizeable energy gaps and quasi-Floquet energy bands that form on femtosecond\ntime scales. By analyzing Floquet energy level crossings and snapshots of\npseudospin textures near the Dirac points, we identify transitions to new\nstates with optically induced nontrivial changes of sublattice mixing that can\nlead to Berry curvature corrections of electrical transport and magnetization."
    },
    {
        "anchor": "Unidirectional tilt of domain walls in equilibrium in biaxial stripes\n  with Dzyaloshinskii-Moriya interaction: The orientation of a chiral magnetic domain wall in a racetrack determines\nits dynamical properties. In equilibrium, magnetic domain walls are expected to\nbe oriented perpendicular to the stripe axis. We demonstrate the appearance of\na unidirectional domain wall tilt in out-of-plane magnetized stripes with\nbiaxial anisotropy and Dzyaloshinskii--Moriya interaction (DMI). The tilt is a\nresult of the interplay between the in-plane easy-axis anisotropy and DMI. We\nshow that the additional anisotropy and DMI prefer different domain wall\nstructure: anisotropy links the magnetization azimuthal angle inside the domain\nwall with the anisotropy direction in contrast to DMI, which prefers the\nmagnetization perpendicular to the domain wall plane. Their balance with the\nenergy gain due to domain wall extension defines the equilibrium magnetization\nthe domain wall tilting. We demonstrate that the Walker field and the\ncorresponding Walker velocity of the domain wall can be enhanced in the system\nsupporting tilted walls.",
        "positive": "Exploring the transport properties of polytypic and twin-plane\n  nanowires: from tunneling phase-time to spin-orbit interaction effects: The variety of nanowire crystal structures gave rise to unique and novel\ntransport phenomena. In particular, we have explored the superlattice profile\ngenerated by strain field modulation in twinplane nanowires for the tuning of\ntransport channels and the built-in spin-orbit potential profile of polytypic\nnanowires, in order to realize a spin filter. The Multicomponent Scattering\nApproach has been used in terms of the Transfer Matrix Method to describe the\nphase-time of charge carriers. This system showed advantages for attaining\nconditions for the propagation of wave packets with negative group velocity.\nMoreover, the spin transport effect of a potential profile with volumetric\nspin-orbit bulk inversion asymmetry, as present on polytypic nanowires, was\ndescribed through the Reverse Runge-Kutta Method. Using the peculiar symmetry\nof the excited states we have characterized a dominant spin dependence on\nstructural parameters that results in effective spin filtering."
    },
    {
        "anchor": "Strain- and Adsorption-Dependent Electronic States and Transport or\n  Localization in Graphene: The chapter generalizes results on influence of uniaxial strain and\nadsorption on the electron states and charge transport or localization in\ngraphene with different configurations of imperfections (point defects):\nresonant (neutral) adsorbed atoms either oxygen- or hydrogen-containing\nmolecules or functional groups, vacancies or substitutional atoms, charged\nimpurity atoms or molecules, and distortions. To observe electronic properties\nof graphene-admolecules system, we applied electron paramagnetic resonance\ntechnique in a broad temperature range for graphene oxides as a good basis for\nunderstanding the electrotransport properties of other active carbons. Applied\ntechnique allowed observation of possible metal-insulator transition and\nsorption pumping effect as well as discussion of results in relation to the\ngranular metal model. The electronic and transport properties are calculated\nwithin the framework of the tight-binding model along with the Kubo-Greenwood\nquantum-mechanical formalism. Depending on electron density and type of the\nsites, the conductivity for correlated and ordered adsorbates is found to be\nenhanced in dozens of times as compared to the cases of their random\ndistribution. In case of the uniaxially strained graphene, the presence of\npoint defects counteracts against or contributes to the band-gap opening\naccording to their configurations. The band-gap behaviour is found to be\nnonmonotonic with strain in case of a simultaneous action of defect ordering\nand zigzag deformation. The amount of localized charge carriers (spins) is\nfound to be correlated with the content of adsorbed centres responsible for the\nformation of potential barriers and, in turn, for the localization effects.\nPhysical and chemical states of graphene edges, especially at a uniaxial strain\nalong one of them, play a crucial role in electrical transport phenomena in\ngraphene-based materials.",
        "positive": "Topological phase of the interlayer exchange coupling with application\n  to magnetic switching: We show, theoretically, that the phase of the interlayer exchange coupling\n(IEC) undergoes a topological change of approximately $2\\pi$ as the chemical\npotential of the ferromagnetic (FM) lead moves across a hybridization gap (HG).\nThe effect is largely independent of the detailed parameters of the system, in\nparticular the width of the gap. The implication is that for a narrow gap, a\nsmall perturbation in the chemical potential of the lead can give a sign\nreversal of the exchange coupling. This offers the possibility of controlling\nmagnetization switching in spintronic devices such as MRAM, with little power\nconsumption. Furthermore we believe that this effect has already been\nindirectly observed, in existing measurements of the IEC as a function of\ntemperature and of doping of the leads."
    },
    {
        "anchor": "Effect of detuning on the phonon induced dephasing of optically driven\n  InGaAs/GaAs quantum dots: Recently, longitudinal acoustic phonons have been identified as the main\nsource of the intensity damping observed in Rabi rotation measurements of the\nground-state exciton of a single InAs/GaAs quantum dot. Here we report\nexperiments of intensity damped Rabi rotations in the case of detuned laser\npulses, the results have implications for the coherent optical control of both\nexcitons and spins using detuned laser pulses.",
        "positive": "Electronic cooling of a submicron-sized metallic beam: We demonstrate electronic cooling of a suspended AuPd island using\nsuperconductor-insulator-normal metal tunnel junctions. This was achieved by\ndeveloping a simple fabrication method for reliably releasing narrow submicron\nsized metal beams. The process is based on reactive ion etching and uses a\nconducting substrate to avoid charge-up damage and is compatible with e.g.\nconventional e-beam lithography, shadow-angle metal deposition and oxide tunnel\njunctions. The devices function well and exhibit clear cooling; up to factor of\ntwo at sub-kelvin temperatures."
    },
    {
        "anchor": "Multiband ballistic transport and anisotropic commensurability\n  magnetoresistance in antidot lattices of AB-stacked trilayer graphene: Ballistic transport was studied in a multiple-band system consisting of an\nantidot lattice of AB-stacked trilayer graphene. The low temperature\nmagnetoresistance showed commensurability peaks arising from matching of the\nantidot lattice period and radius of cyclotron orbits for each mono- and\nbilayer-like band in AB stacked trilayer graphene. The commensurability peak of\nthe monolayer-like band appeared at a lower magnetic field than that of the\nbilayer-like band, which reflects the fact that the Fermi surface of the\nbilayer-like band is larger than that of monolayer-like band. Rotation of the\nantidot lattice relative to the crystallographic axes of graphene resulted in\nanisotropic magnetoresistance, which reflects the trigonally warped Fermi\nsurface of the bilayer-like band. Numerical simulations of magnetoresistance\nthat assumed ballistic transport in the mono- and bilayer-like bands\napproximately reproduced the observed magnetoresistance features. It was found\nthat the monolayer-like band significantly contributes to the conductivity even\nthough its carrier density is an order smaller than that of the bilayer-like\nband. These results indicate that ballistic transport experiments could be used\nfor studying the anisotropic band structure of multiple-band systems.",
        "positive": "Renormalization of the dephasing by zero point fluctuations: We study the role of zero-point-fluctuations (ZPF) in dephasing at low\ntemperature. Unlike the Caldeira-Leggett model where the interaction is with an\nhomogeneous fluctuating field of force, here we consider the effect of short\nrange scattering by localized bath modes. We find that in presence of ZPF the\ninelastic cross-section gets renormalized. Thus indirectly ZPF might contribute\nto the dephasing at low temperature."
    },
    {
        "anchor": "Sudden modulation theory of hole spin-3/2 relaxation: We investigate the hole spin-3/2 relaxation process induced by nonadiabatic\nstochastic modulations of the instantaneous Luttinger Hamiltonian. The theory\nallows to consider fluctuations of both the direction and the magnitude of a\nhole wave vector in all regimes of momentum scattering: from\ncollision-dominated to ballistic.",
        "positive": "Thermodynamic uncertainty relation in thermal transport: We use the fundamental nonequilibrium steady-state fluctuation symmetry and\nderive a condition on the validity of the thermodynamic uncertainty relation\n(TUR) in thermal transport problems, classical or quantum alike. We test this\ncondition and study the breakdown of the TUR in different thermal transport\njunctions of bosonic and electronic degrees of freedom. First, we prove that\nthe TUR is valid in harmonic oscillator junctions. In contrast, in the\nnonequilibrium spin-boson model, which realizes many-body effects, it is\nsatisfied in the Markovian limit, but violations arise as we tune (reduce) the\ncutoff frequency of the thermal baths, thus observing non-Markovian dynamics.\nFinally, we consider heat transport by noninteracting electrons in a\ntight-binding chain model. Here we show that the TUR is feasibly violated by\ntuning e.g. the hybridization energy of the chain to the metal leads. These\nresults manifest that the validity of the TUR relies on the statistics of the\nparticipating carriers, their interaction, and the nature of their couplings to\nthe macroscopic contacts (metal electrodes, phonon baths)."
    },
    {
        "anchor": "Dynamical Coulomb Blockade as a Local Probe for Quantum Transport: Quantum fluctuations are imprinted with valuable information about transport\nprocesses. Experimental access to this information is possible, but\nchallenging. We introduce the dynamical Coulomb blockade (DCB) as a local probe\nfor fluctuations in a scanning tunneling microscope (STM) and show that it\nprovides information about the conduction channels. In agreement with\ntheoretical predictions, we find that the DCB disappears in a single-channel\njunction with increasing transmission following the Fano factor, analogous to\nwhat happens with shot noise. Furthermore we demonstrate local differences in\nthe DCB expected from changes in the conduction channel configuration. Our\nexperimental results are complemented by ab initio transport calculations that\nelucidate the microscopic nature of the conduction channels in our atomic-scale\ncontacts. We conclude that probing the DCB by STM provides a technique\ncomplementary to shot noise measurements for locally resolving quantum\ntransport characteristics.",
        "positive": "Effect of dilute impurities on short graphene Josephson junctions: We study the effect of a dilute homogeneous spatial distribution of\nnon-magnetic impurities on the equilibrium supercurrent sustained by a\nballistic graphene Josephson junction in the short junction limit. Within the\nDirac-Bogoliubov-de Gennes approach and modeling impurities by the Anderson\nmodel we derive the supercurrent and its equilibrium power spectrum. We find a\nmodification of the current-phase relation with a reduction of the skewness\ninduced by disorder, and a nonmonotonic temperature dependence of the critical\ncurrent. The potentialities of the supercurrent power spectrum for accurate\nspectroscopy of the hybridized Andreev bound states-impurities spectrum are\nhighlighted. In the low temperature limit, the supercurrent zero frequency\nthermal noise directly probes the spectral function at the Fermi energy."
    },
    {
        "anchor": "Tuning decoherence with a voltage probe: We present an experiment where we tune the decoherence in a quantum\ninterferometer using one of the simplest object available in the physic of\nquantum conductors : an ohmic contact. For that purpose, we designed an\nelectronic Mach-Zehnder interferometer which has one of its two arms connected\nto an ohmic contact through a quantum point contact. At low temperature, we\nobserve quantum interference patterns with a visibility up to 57%. Increasing\nthe connection between one arm of the interferometer to the floating ohmic\ncontact, the voltage probe, reduces quantum interferences as it probes the\nelectron trajectory. This unique experimental realization of a voltage probe\nworks as a trivial which-path detector whose efficiency can be simply tuned by\na gate voltage.",
        "positive": "Absolutely continuous energy bands and extended electronic states in an\n  aperiodic comb-shaped nanostructure: The nature of electronic eigenstates and quantum transport in a comb-shaped\nFibonacci nanostructure model is investigated within a tight-binding framework.\nPeriodic linear chains are side-attached to a Fibonacci chain, giving it the\nshape of an aperiodic comb. The effect of the side-attachments on the usual\nCantor set energy spectrum of a Fibonacci chain is analyzed using the Greens\nfunction technique. A special correlation between the coupling of the\nside-attached chain with the Fibonacci chain and the inter-atomic coupling of\nthe Fibonacci chain results in a dramatic triggering of the fragmented Cantor\nset energy spectrum into multiple sets of continuous sub-bands of extended\neigenstates. The result is valid even for a disordered comb and turns out to be\na rare exception of the conventional Anderson localization problem. The\nelectronic transport thus can be made selectively ballistic within desired\nenergy regimes. The number and the width of such continuous sub-bands can be\neasily controlled by tuning the number of atomic sites in the side-coupled\nperiodic linear chains. This gives us a scope of proposing such aperiodic\nnanostructures as potential candidates for prospective energy selective\nnanoscale filtering devices."
    },
    {
        "anchor": "Bosonic condensation of exciton-polaritons in an atomically thin crystal: The emergence of two-dimensional crystals has revolutionized modern\nsolid-state physics. From a fundamental point of view, the enhancement of\ncharge carrier correlations has sparked enormous research activities in the\ntransport- and quantum optics communities. One of the most intriguing effects,\nin this regard, is the bosonic condensation and spontaneous coherence of\nmany-particle complexes. Here, we find compelling evidence of bosonic\ncondensation of exciton-polaritons emerging from an atomically thin crystal of\nMoSe2 embedded in a dielectric microcavity under optical pumping. The formation\nof the condensate manifests itself in a sudden increase of luminescence\nintensity in a threshold-like manner, and a significant spin-polarizability in\nan externally applied magnetic field. Spatial coherence is mapped out via\nhighly resolved real-space interferometry, revealing a spatially extended\ncondensate. Our device represents a decisive step towards the implementation of\ncoherent light-sources based on atomically thin crystals, as well as\nnon-linear, valleytronic coherent devices.",
        "positive": "Enhancement of persistent currents due to confinement in metallic\n  samples: Confinement and surface roughness (SR) effects on the magnitude of the\npersistent current are analized for ballistic bidimensional metallic samples.\nDepending on the particular geometry, localized border states can show up at\nhalf filling. These border states contribute coherently to the persistent\ncurrent and its magnitude is enhanced with respect to their value in the absent\nof confinement. A linear scaling of the typical current $I_{typ}$ with the\nnumber of conduction channels M is obtained. This result is robust with respect\nto changes in the relevant lengths of the samples and to the SR. Possible links\nof our results to experiments are also discussed."
    },
    {
        "anchor": "Adiabatic pumping through interacting quantum dots: We present a general formalism to study adiabatic pumping through interacting\nquantum dots. We derive a formula that relates the pumped charge to the local,\ninstantaneous Green function of the dot. This formula is then applied to the\ninfinite-U Anderson model both for weak and strong tunnel-coupling strengths.",
        "positive": "Tuning the Electronic Structure of Monolayer Graphene/MoS2 van der Waals\n  Heterostructures via Interlayer Twist: We directly measure the electronic structure of twisted graphene/MoS2 van der\nWaals heterostructures, in which both graphene and MoS2 are monolayers. We use\ncathode lens microscopy and microprobe angle-resolved photoemission\nspectroscopy measurements to image the surface, determine twist angle, and map\nthe electronic structure of these artificial heterostructures. For monolayer\ngraphene on monolayer MoS2, the resulting band structure reveals the absence of\nhybridization between the graphene and MoS2 electronic states. Further, the\ngraphene-derived electronic structure in the heterostructures remains intact,\nirrespective of the twist angle between the two materials. In contrast,\nhowever, the electronic structure associated with the MoS2 layer is found to be\ntwist-angle dependent; in particular, the relative difference in the energy of\nthe valence band maximum at {\\Gamma} and K of the MoS2 layer varies from\napproximately 0 to 0.2 eV. Our results suggest that monolayer MoS2 within the\nheterostructure becomes predominantly an indirect bandgap system for all twist\nangles except in the proximity of 30 degrees. This result enables potential\nbandgap engineering in van der Waals heterostructures comprised of monolayer\nstructures."
    },
    {
        "anchor": "Frequency dependence of induced spin polarization and spin current in\n  quantum wells: Dynamic response of two-dimensional electron systems with spin-orbit\ninteraction is studied theoretically on the basis of quantum kinetic equation,\ntaking into account elastic scattering of electrons. The spin polarization and\nspin current induced by the applied electric field are calculated for the whole\nclass of electron systems described by p-linear spin-orbit Hamiltonians. The\nabsence of nonequilibrium intrinsic static spin currents is confirmed for these\nsystems with arbitrary (nonparabolic) electron energy spectrum. Relations\nbetween the spin polarization, spin current, and electric current are\nestablished. The general results are applied to the quantum wells grown in\n[001] and [110] crystallographic directions, with both Rashba and Dresselhaus\ntypes of spin-orbit coupling. It is shown that the existence of the fixed\n(momentum-independent) precession axes in [001]-grown wells with equal Rashba\nand Dresselhaus spin velocities or in symmetric [110]-grown wells leads to\nvanishing spin polarizability at arbitrary frequency of the applied electric\nfield. This property is explained by the absence of Dyakonov-Perel-Kachorovskii\nspin relaxation for the spins polarized along these precession axes. As a\nresult, a considerable frequency dispersion of spin polarization at very low\nfrequency in the vicinity of the fixed precession axes is predicted. Possible\neffects of extrinsic spin-orbit coupling on the obtained results are discussed.",
        "positive": "Influence of non-collisional laser heating on the electron dynamics in\n  dielectric materials: The electron dynamics in dielectric materials induced by intense femtosecond\nlaser pulses is theoretically addressed. The laser driven temporal evolution of\nthe energy distribution of electrons in the conduction band is described by a\nkinetic Boltzmann equation. In addition to the collisional processes for energy\ntransfer such as electron-phonon-photon and electron-electron interactions, a\nnon-collisional process for photon absorption in the conduction band is\nincluded. It relies on direct transitions between sub-bands of the conduction\nband through multiphoton absorption. This mechanism is shown to significantly\ncontribute to the laser heating of conduction electrons for large enough laser\nintensities. It also increases the time required for the electron distribution\nto reach the equilibrium state as described by the Fermi-Dirac statistics.\nQuantitative results are provided for quartz irradiated by a femtosecond laser\npulse with a wavelength of 800 nm and for intensities in the range of tens of\nTW/cm$^2$, lower than the ablation threshold. The change in the energy\ndeposition induced by this non-collisional heating process is expected to have\na significant influence on the laser processing of dielectric materials."
    },
    {
        "anchor": "Optimal dispersive readout of a spin qubit with a microwave resonator: Strong coupling of semiconductor spin qubits to superconducting microwave\nresonators was recently demonstrated. These breakthroughs pave the way for\nquantum information processing that combines the long coherence times of\nsolid-state spin qubits with the long-distance connectivity, fast control, and\nfast high-fidelity quantum-non-demolition readout of existing superconducting\nqubit implementations. Here, we theoretically analyze and optimize the\ndispersive readout of a single spin in a semiconductor double quantum dot (DQD)\ncoupled to a microwave resonator via its electric dipole moment. The strong\nspin-photon coupling arises from the motion of the electron spin in a local\nmagnetic field gradient. We calculate the signal-to-noise ratio (SNR) of the\nreadout accounting for both Purcell spin relaxation and spin relaxation arising\nfrom intrinsic electric noise within the semiconductor. We express the maximum\nachievable SNR in terms of the cooperativity associated with these two\ndissipation processes. We find that while the cooperativity increases with the\nstrength of the dipole coupling between the DQD and the resonator, it does not\ndepend on the strength of the magnetic field gradient. We then optimize the SNR\nas a function of experimentally tunable DQD parameters. We identify wide\nregions of parameter space where the unwanted backaction of the resonator\nphotons on the qubit is small. Moreover, we find that the coupling of the\nresonator to other DQD transitions can enhance the SNR by at least a factor of\ntwo, a ``straddling'' effect that occurs only at nonzero energy detuning of the\nDQD double-well potential. We estimate that with current technology,\nsingle-shot readout fidelities in the range $82-95\\%$ can be achieved within a\nfew $\\mu\\textrm{s}$ of readout time without requiring the use of Purcell\nfilters.",
        "positive": "The Berry phase in ferromagnetic spin systems and anomalous Hall Effect: We have shown that the study of topological aspects of the underlying\ngeometry in a ferromagnetic spin system gives rise to an intrinsic Berry phase.\nThis real space Berry phase arises due to the spin rotations of conducting\nelectrons which can be manifested as a further contribution in anomalous Hall\neffect."
    },
    {
        "anchor": "Periodic structure of memory function in spintronics reservoir with\n  feedback current: The role of the feedback effect on physical reservoir computing is studied\ntheoretically by solving the vortex-core dynamics in a nanostructured\nferromagnet. Although the spin-transfer torque due to the feedback current\nmakes the vortex dynamics complex, it is clarified that the feedback effect\ndoes not always contribute to the enhancement of the memory function in a\nphysical reservoir. The memory function, characterized by the correlation\ncoefficient between the input data and the dynamical response of the vortex\ncore, becomes large when the delay time of the feedback current is not an\nintegral multiple of the pulse width. On the other hand, the memory function\nremains small when the delay time is an integral multiple of the pulse width.\nAs a result, a periodic behavior for the short-term memory capacity is observed\nwith respect to the delay time, the phenomenon of which can be attributed to\ncorrelations between the virtual neurons via the feedback current.",
        "positive": "Graphane with carbon dimer defects: Robust in-gap states and a scalable\n  two-dimensional platform for quantum computation: We study the energy level structures of the defective graphane lattice, where\na carbon dimer defect is created by removing the hydrogen atoms on two\nnearest-neighbor carbon sites. Robust defect states emerge inside the bulk\ninsulating gap of graphane. While for the stoichiometric half-filled system\nthere are two doubly degenerate defect levels, there are four nondegenerate and\nspin-polarized in-gap defect levels in the system with one electron less than\nhalf filling. A universal set of quantum gates can be realized in the defective\ngraphane lattice, by triggering resonant transitions among the defect states\nvia optical pulses and \\emph{ac} magnetic fields. The sizable energy separation\nbetween the occupied and the empty in-gap states enables precise control at\nroom temperature. The spatial locality of the in-gap states implies a qubit\nnetwork of extremely high areal density. Based on these results, we propose\nthat graphane as a unique platform could be used to construct the future\nall-purpose quantum computers."
    },
    {
        "anchor": "Stacking faults as quantum wells in nanowires: Density of states,\n  oscillator strength and radiative efficiency: We investigate the nature of excitons bound to I1 basal-plane stacking faults\n[(I1;X)] in GaN nanowire ensembles by continuous-wave and time-resolved\nphotoluminescence spectroscopy. Based on the linear increase of the radiative\nlifetime of these excitons with temperature, they are demonstrated to exhibit a\ntwo-dimensional density of states, i. e., a basal-plane stacking fault acts as\na quantum well. From the slope of the linear increase, we determine the\noscillator strength of the (I1;X) and show that the value obtained reflects the\npresence of large internal electrostatic fields across the stacking fault.\nWhile the recombination of donor-bound and free excitons in the GaN nanowire\nensemble is dominated by nonradiative phenonema already at 10 K, we observe\nthat the (I1;X) recombines purely radiatively up to 60 K. This finding provides\nimportant insight into the nonradiative recombination processes in GaN\nnanowires. First, the radiative lifetime of about 6 ns measured at 60 K sets an\nupper limit for the surface recombination velocity of 450 cm/s considering the\nnanowires mean diameter of 105 nm. Second, the density of nonradiative centers\nresponsible for the fast decay of donor-bound and free excitons cannot be\nhigher than 2x10^16 cm^-3. As a consequence, the nonradiative decay of\ndonor-bound excitons in these GaN nanowire ensembles has to occur indirectly\nvia the free exciton state.",
        "positive": "True, quasi and unstable Nambu Goldstone modes of the twodimensional\n  Bose Einstein condensed magnetoexcitons: The collective elementary excitations of two dimensional magnetoexcitons in a\nBose Einstein condensate with zero wavevector are investigated in the framework\nof the Bogoliubov theory of quasi averages. The Hamiltonian of the electrons\nand holes lying in the lowest Landau levels contains supplementary interactions\ndue to virtual quantum transitions of the particles to the excited Landau\nlevels and back. As a result, the interaction between the magnetoexcitons zero\nwavenumbers does not vanish and their BEC becomes stable. The energy spectrum\ncontains only one gapless,true Nambu Goldstone mode of the second kind,\nproportional to the square of wavenumber at small values of wavenumber\ndescribing the optical plasmon type oscillations. There are two exciton type\nbranches corresponding to normal and abnormal Green functions. Both modes are\ngapped with roton type segments at intermediary values of the wavevectors and\ncan be named quasi NG modes. The fourth branch is the acoustical plasmon type\nmode with absolute instability in the region of small and intermediary values\nof the wavevectors. All branches have a saturation type dependencies at great\nvalues of the wave vectors. The number and the kind of the true NG modes are in\naccordance with the number of the broken symmetry operators."
    },
    {
        "anchor": "Differential current noise as an identifier of Andreev bound states that\n  induce nearly quantized conductance plateaus: Quantized conductance plateaus, a celebrated hallmark of Majorana bound\nstates (MBSs) predicted a decade ago, have recently been observed with small\ndeviations in iron-based superconductors and hybrid nanowires. Here, we\ndemonstrate that nearly quantized conductance plateaus can also arise from\ntrivial Andreev bound states (ABSs). To avoid ABS interruptions, we propose\nidentifying ABS-induced quantized conductance plateaus by measuring the\nassociated differential current noise $P$ versus bias voltage $V$.\nSpecifically, for a quantized conductance plateau induced by one or multiple\nlow-energy ABSs, the associated $P(V)$ curve exhibits a double-peak around zero\nbias, with the peak positions at $e|V|\\approx 3k_B T$ (where $T$ is the\ntemperature) and peak values larger than $2e^3/h$. These features greatly\ncontrast those of an MBS or quasi-MBS, whose $P(V)$ curve displays a broad\nzero-bias dip and is consistently below $2e^3/h$. This protocol can be\npractically implemented in a variety of MBS candidate platforms using an\nelectrode or STM tip as a probe.",
        "positive": "Bridging the Gap between Crystal Theory and Semiconductor Physics: The theory of perfect crystals, founded upon the Bloch theorem, gives an\nunderstanding of extended quantum states grouped into energy bands, and permits\nthe derivation of the dynamics of electrons in those states. The semiconductor\nphysics used to explain the operation of electronic devices treats the\n(imperfect) semiconductor crystal as a uniform effective medium in which\npositively and negatively charged quasi-particles mostly obey Newtonian\ndynamics, and in which the chemistry of impurity atoms is far different from\nthat of those same atoms in free space. The connection between these two\npictures can be made by made by invoking a mathematical transformation that\ntakes the finite-temperature, impure device structure and algebraically\nsubtracts from it a perfect crystal, leaving only the residual differences to\nbe analyzed. This notion of the residual difference offers a conceptual basis\nfor understanding many aspects of semiconductor physics, including the\nproperties of impurity states and heterogeneous interfaces. The mesoscopic\ntransformation that underlies the residual-difference picture provides the\nsystematic way to define a concept that is essential to the understanding of\nsemiconductor devices: a position-dependent band structure."
    },
    {
        "anchor": "Topological Raman Band in Carbon Nanohorn: Raman spectroscopy has been used in chemistry and physics to investigate the\nfundamental process involving light and phonons (quantum of lattice vibration).\nThe carbon nanohorn introduces a new subject to Raman spectroscopy, namely\ntopology. We show theoretically that a photo-excited carrier with a non-zero\nwinding number activates a topological $D$ Raman band through the Aharonov-Bohm\neffect. The topology-induced $D$ Raman band can be distinguished from the\nordinary $D$ Raman band for a graphene edge by its peak position.",
        "positive": "Gate-tunable split Kondo effect in a carbon nanotube quantum dot: We show a detailed investigation of the split Kondo effect in a carbon\nnanotube quantum dot with multiple gate electrodes. It is found that the\nsplitting decreases for increasing magnetic field, to result in a recovered\nzero-bias Kondo resonance at finite magnetic field. Surprisingly, in the same\ncharge state, but under different gate-configurations, the splitting does not\ndisappear for any value of the magnetic field, but we observe an avoided\ncrossing of two high-conductance lines. We think that our observations can be\nunderstood in terms of a two-impurity Kondo effect with two spins coupled\nantiferromagnetically. The exchange coupling between the two spins can be\ninfluenced by a local gate, and the non-recovery of the Kondo resonance for\ncertain gate configurations is explained by the existence of a small\nantisymmetric contribution to the exchange interaction between the two spins."
    },
    {
        "anchor": "Theory of Harmonic Hall Responses of Spin-Torque Driven Antiferromagnets: Harmonic analysis is a powerful tool to characterize and quantify\ncurrent-induced torques acting on magnetic materials, but so far it remains an\nopen question in studying antiferromagnets. Here we formulate a general theory\nof harmonic Hall responses of collinear antiferromagnets driven by\ncurrent-induced torques including both field-like and damping-like components.\nBy scanning a magnetic field of variable strength in three orthogonal planes,\nwe are able to distinguish the contributions from field-like torque,\ndamping-like torque, and concomitant thermal effects by analyzing the second\nharmonic signals in the Hall voltage. The analytical expressions of the first\nand second harmonics as functions of the magnetic field direction and strength\nare confirmed by numerical simulations with good agreement. We demonstrate our\npredictions in two prototype antiferromagnets, $\\alpha-$Fe$_{2}$O$_{3}$ and\nNiO, providing direct and general guidance to current and future experiments.",
        "positive": "Generalized parafermions and non-local Josephson effect in multi-layer\n  systems: We theoretically investigate the effects of backscattering and\nsuperconducting proximity terms between the edges of two multi-layer fractional\nquantum Hall (FQH) systems. While the different layers are strongly\ninteracting, we assume that tunneling between them is absent. Studying the\nboundaries between regions gapped by the two mechanisms in an $N$-layer system,\nwe find $N$ localized zero-mode operators realizing a generalized parafermionic\nalgebra. We further propose an experiment capable of probing imprints of the\ngeneralized parafermionic bound states. This is done by coupling different\nsuperconducting contacts to different layers, and examining the periodicity of\nthe Josephson effect as a function of the various relative superconducting\nphases. Remarkably, even if we apply a phase difference between the\nsuperconductors in one layer, we induce a Josephson current at the other layers\ndue to inter-layer interactions. Furthermore, while the Josephson effect is\ncommonly used to probe only charged degrees of freedom, the possibility of\nindependently controlling the superconducting phase differences between the\nlayers allows us to find imprints of the neutral modes of the underlying\nmulti-layer system. In particular, we propose two configurations, one of which\nis capable of isolating the signal associated with the charge modes, while the\nother probes the neutral modes."
    },
    {
        "anchor": "Coulomb Drag near the metal-insulator transition in two-dimensions: We studied the drag resistivity between dilute two-dimensional hole systems,\nnear the apparent metal-insulator transition. We find the deviations from the\n$T^{2}$ dependence of the drag to be independent of layer spacing and\ncorrelated with the metalliclike behavior in the single layer resistivity,\nsuggesting they both arise from the same origin. In addition, layer spacing\ndependence measurements suggest that while the screening properties of the\nsystem remain relatively independent of temperature, they weaken significantly\nas the carrier density is reduced. Finally, we demonstrate that the drag itself\nsignificantly enhances the metallic $T$ dependence in the single layer\nresistivity.",
        "positive": "Hall resistivity of granular metals: We calculate the Hall conductivity $\\sig_{xy}$ and resistivity $\\rho_{xy}$ of\na granular system at large tunneling conductance $g_{T}\\gg 1$. We show that in\nthe absence of Coulomb interaction the Hall resistivity depends neither on the\ntunneling conductance nor on the intragrain disorder and is given by the\nclassical formula $\\rho_{xy}=H/(n^* e c)$, where $n^*$ differs from the carrier\ndensity $n$ inside the grains by a numerical coefficient determined by the\nshape of the grains. The Coulomb interaction gives rise to logarithmic in\ntemperature $T$ correction to $\\rho_{xy}$ in the range $\\Ga \\lesssim T \\lesssim\n\\min(g_T E_c,\\ETh)$, where $\\Ga$ is the tunneling escape rate, $E_c$ is the\ncharging energy and $\\ETh$ is the Thouless energy of the grain."
    },
    {
        "anchor": "Magnetotransport Signatures of the Radial Rashba Spin-Orbit Coupling in\n  Proximitized Graphene: Graphene-based van der Waals heterostructures take advantage of tailoring\nspin-orbit coupling (SOC) in the graphene layer by proximity effect. At\nlong-wavelength -- saddled by the electronic states near the Dirac points --\nthe proximitized features can be effectively modelled by the Hamiltonian\ninvolving novel SOC terms and allow for an admixture of the tangential and\nradial spin textures -- by the so-called Rashba angle $\\theta_{\\text{R}}$.\nTaking such effective models we perform realistic large-scale magneto-transport\ncalculations -- transverse magnetic focusing and Dyakonov-Perel spin relaxation\n-- and show that there are unique qualitative and quantitative features\nallowing for an unbiased experimental disentanglement of the conventional\nRashba SOC from its novel radial counterpart, called here the radial Rashba\nSOC. Along with that, we propose a scheme for a direct estimation of the Rashba\nangle by exploring the magneto-response symmetries when swapping an in-plane\nmagnetic field. To complete the story, we analyze the magneto-transport\nsignatures in the presence of an emergent Dresselhaus SOC and also provide some\ngeneric ramifications about possible scenarios of the radial superconducting\ndiode effect.",
        "positive": "Spin transport in an electrically-driven magnon gas near Bose-Einstein\n  condensation: Hartree-Fock-Keldysh theory: An easy-plane ferromagnetic insulator in a uniform external magnetic field\nand in contact with a phonon bath and a normal metal bath is studied\ntheoretically in the presence of dc spin current injection via the spin Hall\neffect in the metal. The Keldysh path integral formalism is used to model the\nmagnon gas driven into a nonequilibrium steady state by mismatched bath\ntemperatures and/or electrical injection, and we analyze the magnon system in\nthe normal (uncondensed) state, but close to the instability to Bose-Einstein\ncondensation (BEC), within the self-consistent Hartree-Fock approximation. We\nfind that the steady state magnon distribution function generally has a\nnon-thermal form that cannot be described by a single effective chemical\npotential and effective temperature. We also show that the BEC instability in\nthe electrically-driven magnon system is signaled by a sign change in the\nimaginary part of the poles for long-wavelength magnon modes and by the\ndivergence of the nonequilibrium magnon distribution function. In the presence\nof two bath temperatures, we find that the correlation length of the superfluid\norder parameter fluctuations exhibits nontrivial finite temperature crossover\nbehaviors that are richer than the standard crossover behaviors obtained for\nthe vacuum-superfluid transition in an equilibrium dilute Bose gas. We study\nthe consequences of these thermal crossovers on the magnon spin conductivity\nand obtain an inverse square-root divergence in the spin conductivity in the\nvicinity of the electrically-induced BEC instability. A spintronics device\ncapable of testing our spin transport predictions is discussed."
    },
    {
        "anchor": "Phononic heat transport in the transient regime: An analytic solution: We investigate the time-resolved quantum transport properties of phonons in\narbitrary harmonic systems connected to phonon baths at different temperatures.\nWe obtain a closed analytic expression of the time-dependent one-particle\nreduced density matrix by explicitly solving the equations of motion for the\nnonequilibrium Green's function. This is achieved through a well-controlled\napproximation of the frequency-dependent bath self-energy. Our result allows\nfor exploring transient oscillations and relaxation times of local heat\ncurrents, and correctly reduces to an earlier known result in the steady-state\nlimit. We apply the formalism to atomic chains, and benchmark the validity of\nthe approximation against full numerical solutions of the bosonic\nKadanoff--Baym equations for the Green's function. We find good agreement\nbetween the analytic and numerical solutions for weak contacts and baths with a\nwide energy dispersion. We further analyze relaxation times from low to high\ntemperature gradients.",
        "positive": "Transconductance and effective Land\u00e9 factors for quantum point\n  contacts: spin-orbit coupling and interaction effects: We analyze the effective $g^*$ factors and their dependence on the\norientation of the external magnetic field for a quantum point contact defined\nin the two-dimensional electron gas. The paper simulates the experimental\nprocedure for evaluation of the effective Land\\'e factors from the\ntransconductance of a biased device in external magnetic field. The\ncontributions of the orbital effects of the magnetic field, the\nelectron-electron interaction and spin-orbit (SO) coupling are studied. The\nanisotropy of the $g^*$ factors for the in-plane magnetic field orientation,\nwhich seems counterintuitive from the perspective of the effective SO magnetic\nfield, is explained in an analytical model of the constriction as due to the\nSO-induced subband mixing. The asymmetry of the transconductance as a function\nof the gate voltage is obtained in agreement with the experimental data and the\nresults are explained as due to the depletion of the electron gas within the\nquantum point contact constriction and the related reduction of the screening\nas described within the DFT approach. The results for transconductance and the\n$g^*$ factors are in a good agreement with the experimental data [Phys. Rev. B\n{\\bf 81}, 041303, 2010]."
    },
    {
        "anchor": "Majorana bound states in nanowire-superconductor hybrid systems in\n  periodic magnetic fields: We study how the shape of a periodic magnetic field affects the presence of\nMajorana bound states (MBS) in a nanowire-superconductor system. Motivated by\nthe field configurations that can be produced by an array of nanomagnets, we\nconsider spiral fields with an elliptic cross-section and fields with two\nsinusoidal components. We show that MBS are robust to imperfect helical\nmagnetic fields. In particular, if the amplitude of one component is tuned to\nthe value determined by the superconducting order parameter in the wire, the\nMBS can exist even if the second component has a much smaller amplitude. We\nalso explore the effect of the chemical potential on the phase diagram. Our\nanalysis is both numerical and analytical, with good agreement between the two\nmethods.",
        "positive": "Longitudinal Eigenvibration of Multilayer Colloidal Crystals and the\n  Effect of Nanoscale Contact Bridges: Longitudinal contact-based vibrations of colloidal crystals with a controlled\nlayer thickness are studied. These crystals consist of 390 nm diameter\npolystyrene spheres arranged into close packed, ordered lattices with a\nthickness of one to twelve layers. Using laser ultrasonics, eigenmodes of the\ncrystals that have out-of-plane motion are excited. The particle-substrate and\neffective interlayer contact stiffnesses in the colloidal crystals are\nextracted using a discrete, coupled oscillator model. Extracted stiffnesses are\ncorrelated with scanning electron microscope images of the contacts and atomic\nforce microscope characterization of the substrate surface topography after\nremoval of the spheres. Solid bridges of nanometric thickness are found to\ndrastically alter the stiffness of the contacts, and their presence is found to\nbe dependent on the self-assembly process. Measurements of the eigenmode\nquality factors suggest that energy leakage into the substrate plays a role for\nlow frequency modes but is overcome by disorder- or material-induced losses at\nhigher frequencies. These findings help further the understanding of the\ncontact mechanics, and the effects of disorder in three-dimensional micro- and\nnano-particulate systems, and open new avenues to engineer new types of micro-\nand nanostructured materials with wave tailoring functionalities via control of\nthe adhesive contact properties."
    },
    {
        "anchor": "Proposed Method for Distinguishing Majorana Peak from Other Peaks:\n  Tunneling Spectroscopy with Ohmic Dissipation using Resistive Electrodes: We propose a scheme to distinguish zero-energy peaks due to Majorana from\nthose due to other effects at finite temperature by simply replacing the normal\nmetallic lead with a resistive lead (large R k\\Omega) in the tunneling\nspectroscopy. The dissipation effects due to the large resistance change the\ntunneling conductance significantly in different ways. The Majorana peak\nremains increase as temperature decreases G T^(2r-1) for r=e^2 R/h<1/2. The\nzero-energy peak due to other effects splits into two peaks at finite\ntemperature and the conductance at zero voltage bias varies with temperature by\na power law. The dissipative tunneling with a Majorana mode belongs to a same\nuniversal class as the unstable critical point of the case with a non-Majorana\nmode.",
        "positive": "Thermoelectric transport in monolayer phosphorene: We apply the generalized Boltzmann theory to describe thermoelectric\ntransport properties of monolayer phosphorene in the presence of short- and\nlong-range charged impurity interactions. First, we propose a low-energy\nHamiltonian to explore the accurate electronic band structure of phosphorene in\ncomparison with those results obtained by density-functional simulations. We\nexplain the effect of the coupling between the conduction and valence bands on\nthe thermoelectric properties. We show that the electric conductivity of\nphosphorene is highly anisotropic, while the Seebeck coefficient and figure of\nmerit, without being influenced via either the presence or absence of the\ncoupling term, are nearly isotropic. Furthermore, we demonstrate that the\nconductivity for the $n$ type of doping is more influenced by the coupling term\nthan that of the $p$ type. Along with thermopower sign change, profound\nthermoelectric effects can be achieved."
    },
    {
        "anchor": "Recent progress in parallel fabrication of individual single walled\n  carbon nanotube devices: Single walled carbon nanotubes (SWNTs) have attracted immense research\ninterest because of their remarkable physical and electronic properties. In\nparticular, electronic devices fabricated using individual SWNT have shown\noutstanding device performance surpassing those of Si. However, for the\nwidespread application of SWNTs based electronic devices, parallel fabrication\ntechniques along with Complementary Metal Oxide (CMOS) compatibility are\nrequired. One technique that has the potential to integrate SWNTs at the\nselected position of the circuit in a parallel fashion is AC dielectrophoresis\n(DEP). In this paper, we review recent progress in the parallel fabrication of\nSWNT-based devices using DEP. The review begins with a theoretical background\nfor the DEP and then discusses various parameters affecting DEP assembly of\nSWNTs. We also review the electronic transport properties of the DEP assembled\ndevices and show that high performance devices can be fabricated using DEP. The\ntechnique for fabricating all semiconducting field effect transistor using DEP\nis also reviewed. Finally, we discuss the challenges and opportunities for the\nDEP assembly of SWNTs.",
        "positive": "Universal density scaling of disorder-limited low-temperature\n  conductivity in high-mobility two-dimensional systems: We theoretically consider the carrier density dependence of low-temperature\nelectrical conductivity in high-quality and low-disorder two-dimensional (2D)\n`metallic' electronic systems such as 2D GaAs electron or hole quantum wells or\ngated graphene. Taking into account resistive scattering by Coulomb disorder\narising from quenched random charged impurities in the environment, we show\nthat the 2D conductivity \\sigma(n) varies as \\sigma ~ n^{\\beta(n)} as a\nfunction of the 2D carrier density n where the exponent \\beta(n) is a smooth,\nbut non-monotonic, function of density with possible nontrivial extrema. In\nparticular, the density scaling exponent \\beta(n) depends qualitatively on\nwhether the Coulomb disorder arises primarily from remote or background charged\nimpurities or short-range disorder, and can, in principle, be used to\ncharacterize the nature of the dominant background disorder. A specific\nimportant prediction of the theory is that for resistive scattering by remote\ncharged impurities, the exponent \\beta can reach a value as large as 2.7 for\nk_F d ~ 1, where k_F ~\\sqrt{n} is the 2D Fermi wave vector and d is the\nseparation of the remote impurities from the 2D layer. Such an exponent \\beta\n(>5/2) is surprising because unscreened Coulomb scattering by remote impurities\ngives a limiting theoretical scaling exponent of \\beta = 5/2, and naively one\nwould expect \\beta(n) \\le 5/2 for all densities since unscreened Coulomb\nscattering should nominally be the situation bounding the resistive scattering\nfrom above. We find numerically and show theoretically that the maximum value\nof \\alpha (\\beta), the mobility (conductivity) exponent, for 2D semiconductor\nquantum wells is around 1.7 (2.7) for all values of d (and for both electrons\nand holes) with the maximum \\alpha occurring around k_F d ~ 1. We discuss\nexperimental scenarios for the verification of our theory."
    },
    {
        "anchor": "Long-lived binary tunneling spectrum in a quantum-Hall\n  Tomonaga-Luttinger liquid: The existence of long-lived non-equilibrium states without showing\nthermalization, which has previously been demonstrated in time evolution of\nultracold atoms, suggests the possibility of their spatial analogue in\ntransport behavior of interacting electrons in solid-state systems. Here we\nreport long-lived non-equilibrium states in one-dimensional edge channels in\nthe integer quantum Hall regime. An indirect heating scheme in a\ncounterpropagating configuration is employed to generate a non-trivial binary\nspectrum consisting of high- and low-temperature components. This unusual\nspectrum is sustained even after travelling 5 - 10 {\\mu}m, much longer than the\nlength for electronic relaxation (about 0.1 {\\mu}m), without showing\nsignificant thermalization. This observation is consistent with the integrable\nmodel of Tomonaga-Luttinger liquid. The long-lived spectrum implies that the\nsystem is well described by non-interacting plasmons, which are attractive for\ncarrying information for a long distance.",
        "positive": "Anomalous nonlinearity of the magnonic edge mode: Nonlinearity of magneto-dynamics is typically described by a single constant,\n$\\mathcal{N}$, with positive and negative values indicating repulsion and\nattraction of magnons, respectively. In thin magnetic films with easy-plane\nmagnetic anisotropy, magnon attraction is typically achieved for an in-plane\nmagnetization. At sufficient stimulus, e.g. via application of spin transfer\ntorque, the attraction can give rise to self-localized magnetic solitons, such\nas spin wave bullets, which shrink as their amplitude increases. In contrast,\nfor an oblique magnetization above a certain critical angle, the repulsion of\nmagnons only allows for propagating modes, which expand when pumped more\nstrongly. Here we demonstrate, both analytically and using micromagnetic\nsimulations, that such a dichotomic description is inadequate for magnonic edge\nmodes, which naturally appear in confined magnetic systems. In particular, we\ndemonstrate that the confinement potential of such modes is nonlinear in nature\nand its contribution makes $\\mathcal{N}$ non-monotonically dependent on their\namplitude. As a prominent example, edge modes show compression and expansion\nfor negative and positive $\\mathcal{N}$, yet remain localized. In striking\ncontrast to the extended geometries, edge magnons might also repeal even for an\nin-plane magnetization."
    },
    {
        "anchor": "Topological framework for directional amplification in\n  driven-dissipative cavity arrays: Directional amplification, in which signals are selectively amplified\ndepending on their propagation direction, has attracted much attention as key\nresource for applications, including quantum information processing. Recently,\nseveral, physically very different, directional amplifiers have been proposed\nand realized in the lab. In this work, we present a unifying framework based on\ntopology to understand non-reciprocity and directional amplification in\ndriven-dissipative cavity arrays. Specifically, we unveil a one-to-one\ncorrespondence between a non-zero topological invariant defined on the spectrum\nof the dynamic matrix and regimes of directional amplification, in which the\nend-to-end gain grows exponentially with the number of cavities. We compute\nanalytically the scattering matrix, the gain and reverse gain, showing their\nexplicit dependence on the value of the topological invariant. Parameter\nregimes achieving directional amplification can be elegantly obtained from a\ntopological `phase diagram', which provides a guiding principle for the design\nof both phase-preserving and phase-sensitive multimode directional amplifiers.",
        "positive": "Wigner Molecular Crystals from Multi-electron Moir\u00e9 Artificial Atoms: Semiconductor moir\\'e superlattices provide a versatile platform to engineer\nnew quantum solids composed of artificial atoms on moir\\'e sites. Previous\nstudies have mostly focused on the simplest correlated quantum solid - the\nFermi-Hubbard model - where intra-atom interactions are simplified to a single\nonsite repulsion energy U. These studies have revealed novel quantum phases\nranging from Mott insulators to quantum anomalous Hall insulators at a filling\nof one electron per moir\\'e unit cell. New types of quantum solids should arise\nat even higher filling factors where the multi-electron configuration of\nmoir\\'e artificial atoms provides new degrees of freedom. Here we report the\nexperimental observation of Wigner molecular crystals emerging from\nmulti-electron artificial atoms in twisted bilayer WS2 moir\\'e superlattices.\nMoir\\'e artificial atoms, unlike natural atoms, can host qualitatively\ndifferent electron states due to the interplay between quantized energy levels\nand Coulomb interactions. Using scanning tunneling microscopy (STM), we\ndemonstrate that Wigner molecules appear in multi-electron artificial atoms\nwhen Coulomb interactions dominate. Three-electron Wigner molecules, for\nexample, are seen to exhibit a characteristic trimer pattern. The array of\nWigner molecules observed in a moir\\'e superlattice comprises a new crystalline\nphase of electrons: the Wigner molecular crystal. We show that these Wigner\nmolecular crystals are highly tunable through mechanical strain, moir\\'e\nperiod, and carrier charge type. Our study presents new opportunities for\nexploring quantum phenomena in moir\\'e quantum solids composed of\nmulti-electron artificial atoms."
    },
    {
        "anchor": "Magneto-gyrotropic effects in semiconductor quantum wells (review): Magneto-gyrotropic photogalvanic effects in quantum wells are reviewed. We\ndiscuss experimental data, results of phenomenological analysis and microscopic\nmodels of these effects. The current flow is driven by spin-dependent\nscattering in low-dimensional structures gyrotropic media resulted in asymmetry\nof photoexcitation and relaxation processes. Several applications of the\neffects are also considered.",
        "positive": "Circular photocurrent in Weyl semimetals with mirror symmetry: We have studied theoretically the Weyl semimetals the point symmetry group of\nwhich has reflection planes and which contain equivalent valleys with opposite\nchiralities. These include the most frequently studied compounds, namely the\ntransition metals monopnictides TaAs, NbAs, TaP, NbP, and also Bi$_{1-x}$Sb$_x$\nalloys. The circular photogalvanic current, which inverts its direction under\nreversal of the light circular polarization, has been calculated for the light\nabsorption under direct optical transitions near the Weyl points. In the\nstudied materials, the total contribution of all the valleys to the\nphotocurrent is nonzero only beyond the simple Weyl model, namely, if the\neffective electron Hamiltonian is extended to contain either an anisotropic\nspin-dependent linear contribution together with a spin-independent tilt or a\nspin-dependent contribution cubic in the electron wave vector $\\bf{k}$. With\nallowance for the tilt of the energy dispersion cone in a Weyl semimetal of the\n$C_{4v}$ symmetry, the photogalvanic current is expressed in terms of the\ncomponents of the second-rank symmetric tensor that determines the energy\nspectrum of the carriers near the Weyl node; at low temperature, this\ncontribution to the photocurrent is generated within a certain limited\nfrequency range $\\Delta $. The photocurrent due to the cubic corrections, in\nthe optical absorption region, is proportional to the light frequency squared\nand generated both inside and outside the $\\Delta$ window."
    },
    {
        "anchor": "Fingerprints of Majorana fermions in current-correlations measurements\n  from a superconducting tunnel microscope: We compute various current correlation functions of electrons flowing from a\ntopological nanowire to the tip of a superconducting scanning tunnel microscope\nand identify fingerprints of a Majorana bound state. In particular, the spin\nresolved cross-correlations are shown to display a clear distinction between\nthe presence of a such an exotic state (negative correlations) and an Andreev\nbound state (positive correlations). Similarity and differences with\nmeasurements with a normal tunnel microscope are also discussed, like the\nrobustness to finite temperature for instance.",
        "positive": "Cavity-induced switching between Bell-state textures in a quantum dot: Nanoscale quantum dots in microwave cavities can be used as a laboratory for\nexploring electron-electron interactions and their spin in the presence of\nquantized light and a magnetic field. We show how a simple theoretical model of\nthis interplay at resonance predicts complex but measurable effects. New\npolariton states emerge that combine spin, relative modes, and radiation. These\nstates have intricate spin-space correlations and undergo polariton transitions\ncontrolled by the microwave cavity field. We uncover novel topological effects\ninvolving highly correlated spin and charge density that display\nsinglet-triplet and inhomogeneous Bell-state distributions. Signatures of these\ntransitions are imprinted in the photon distribution, which will allow for\noptical read-out protocols in future experiments and nanoscale quantum\ntechnologies."
    },
    {
        "anchor": "Bound states at partial dislocation defects in multipole higher-order\n  topological insulators: The bulk-boundary correspondence, which links a bulk topological property of\na material to the existence of robust boundary states, is a hallmark of\ntopological insulators. However, in crystalline topological materials the\npresence of boundary states in the insulating gap is not always necessary since\nthey can be hidden in the bulk energy bands, obscured by boundary artifacts of\nnon-topological origin, or, in the case of higher-order topology, they can be\ngapped altogether. Crucially, in such systems the interplay between\nsymmetry-protected topology and the corresponding symmetry defects can provide\na variety of bulk probes to reveal their topological nature. For example, bulk\ncrystallographic defects, such as disclinations and dislocations, have been\nshown to bind fractional charges and/or robust localized bound states in\ninsulators protected by crystalline symmetries. Recently, exotic defects of\ntranslation symmetry called partial dislocations have been proposed as a probe\nof higher-order topology. However, it is a herculean task to have experimental\ncontrol over the generation and probing of isolated defects in solid-state\nsystems; hence their use as a bulk probe of topology faces many challenges.\nInstead, here we show that partial dislocation probes of higher-order topology\nare ideally suited to the context of engineered materials. Indeed, we present\nthe first observations of partial-dislocation-induced topological modes in 2D\nand 3D higher-order topological insulators built from circuit-based resonator\narrays. While rotational defects (disclinations) have previously been shown to\nindicate higher-order topology, our work provides the first experimental\nevidence that exotic translation defects (partial dislocations) are bulk\ntopological probes.",
        "positive": "Electronic bandstructure and van der Waals coupling of ReSe2 revealed by\n  high-resolution angle-resolved photoemission spectroscopy: ReSe2 and ReS2 are unusual compounds amongst the layered transition metal\ndichalcogenides as a result of their low symmetry, with a characteristic\nin-plane anisotropy due to in-plane rhenium chains. They preserve inversion\nsymmetry independent of the number of layers and, in contrast to more\nwell-known transition metal dichalcogenides, bulk and few-monolayer Re-TMD\ncompounds have been proposed to behave as electronically and vibrational\ndecoupled layers. Here, we probe for the first time the electronic band\nstructure of bulk ReSe2 by direct nanoscale angle-resolved photoemission\nspectroscopy. We find a highly anisotropic in- and out-of-plane electronic\nstructure, with the valence band maxima located away from any particular\nhigh-symmetry direction. The effective mass doubles its value perpendicular to\nthe Re chains and the interlayer van der Waals coupling generates significant\nelectronic dispersion normal to the layers. Our density functional theory\ncalculations, including spin-orbit effects, are in excellent agreement with\nthese experimental findings."
    },
    {
        "anchor": "Surface acoustic wave coupled to magnetic resonance on a multiferroic\n  CuB$_2$O$_4$: We observed surface acoustic wave (SAW) propagation on a multiferroic\nmaterial CuB$_2$O$_4$ with use of two interdigital transducers (IDTs). The\nperiod of IDT fingers is as short as 1.6 $\\mu$m so that the frequency of SAW is\n3 GHz, which is comparable with that of magnetic resonance. In\nantiferromagnetic phase, the SAW excitation intensity varied with the magnitude\nand direction of the magnetic field, owing to the dynamical coupling between\nSAWs and antiferromagnetic resonance of CuB$_2$O$_4$. The microscopic mechanism\nis discussed based on the symmetrically allowed magentoelastic coupling.",
        "positive": "Local and Non-local Microwave Impedance of a Three-Terminal Hybrid\n  Device: We report microwave impedance measurements of a superconductor-semiconductor\nhybrid nanowire device with three terminals (3T). Our technique makes use of\ntransmission line resonators to acquire the nine complex scattering matrix\nparameters (S-parameters) of the device on fast timescales and across a\nspectrum of frequencies spanning 0.3 - 7 GHz. Via comparison with dc-transport\nmeasurements, we examine the utility of this technique for probing the local\nand non-local response of 3T devices where capacitive and inductive\ncontributions can play a role. Such measurements require careful interpretation\nbut may be of use in discerning true Majorana zero modes from trivial states\narising from disorder."
    },
    {
        "anchor": "Shot noise induced charge and potential fluctuations of edge states in\n  proximity of a gate: We evaluate the RC-time of edge states capacitively coupled to a gate located\naway from a QPC which allows for partial transmission of an edge channel. At\nlong times or low frequencies the RC-time governs the relaxation of charge and\ncurrent and governs the fluctuations of the equilibrium electrostatic\npotential. The RC-time in mesoscopic structures is determined by an\nelectrochemical capacitance which depends on the density of states of the edge\nstates and a charge relaxation resistance. In the non-equilibrium case, in the\npresence of transport, the shot noise leads to charge fluctuations in proximity\nof the gate which are again determined by the equilibrium electrochemical\ncapacitance but with a novel resistance. The case of multiple edge states is\ndiscussed and the effect of a dephasing voltage probe on these resistances is\ninvestigated. The potential fluctuations characterized by these capacitances\nand resistances are of interest since they determine the dephasing rate in\nCoulomb coupled mesoscopic conductors.",
        "positive": "Experimental evidence for the formation of stripe phases in Si/SiGe: We observe pronounced transport anisotropies in magneto-transport experiments\nperformed in the two-dimensional electron system of a Si/SiGe heterostructure.\nThey occur when an in-plane field is used to tune two Landau levels with\nopposite spin to energetic coincidence. The observed anisotropies disappear\ndrastically for temperatures above 1 K. We propose that our experimental\nfindings may be caused by the formation of a unidirectional stripe phase\noriented perpendicular to the in-plane field."
    },
    {
        "anchor": "Interfaces Within Graphene Nanoribbons: We study the conductance through two types of graphene nanostructures:\nnanoribbon junctions in which the width changes from wide to narrow, and curved\nnanoribbons. In the wide-narrow structures, substantial reflection occurs from\nthe wide-narrow interface, in contrast to the behavior of the much studied\nelectron gas waveguides. In the curved nanoribbons, the conductance is very\nsensitive to details such as whether regions of a semiconducting armchair\nnanoribbon are included in the curved structure -- such regions strongly\nsuppress the conductance. Surprisingly, this suppression is not due to the band\ngap of the semiconducting nanoribbon, but is linked to the valley degree of\nfreedom. Though we study these effects in the simplest contexts, they can be\nexpected to occur for more complicated structures, and we show results for\nrings as well. We conclude that experience from electron gas waveguides does\nnot carry over to graphene nanostructures. The interior interfaces causing\nextra scattering result from the extra effective degrees of freedom of the\ngraphene structure, namely the valley and sublattice pseudospins.",
        "positive": "Characterization of spin-orbit fields in InGaAs quantum wells: Coherent electron spin dynamics in 10-nm-wide InGaAs/InAlAs quantum wells is\nstudied from 10 K to room temperature using time-resolved Kerr rotation. The\nspin lifetime exceeds 1 ns at 10 K and decreases with temperature. By varying\nthe spatial overlap between pump and probe pulses, a diffusive velocity is\nimprinted on the measured electron spins and a spin precession in the\nspin-orbit field is measured. A Rashba symmetry of the SOI is determined. By\ncomparing the spatial precession frequency gradient with the spin decay rate,\nan upper limit for the Rashba coefficients $\\alpha$ of 2$\\times$10$^{-12}$ eVm\nis estimated."
    },
    {
        "anchor": "Nonlinear magnetotransport in dual spin valves: Recent experimental measurements of magnetoresistance in dual spin valves [A.\nAziz et al., Phys. Rev. Lett. 103, 237203 (2009)] reveal some nonlinear\nfeatures of transport, which have not been observed in other systems. We\npropose a phenomenological model describing current-dependent resistance (and\ngiant magnetoresistance) in double spin valves. The model is based on a\nmodified Valet-Fert approach, and takes into account the dependence of\nbulk/interface resistance and bulk/interface spin asymmetry parameters for the\ncentral magnetic layer on spin accumulation, and consequently on charge\ncurrent. Such a nonlinear model accounts for recent experimental observations.",
        "positive": "Bright excitons with negative-mass electrons: Bound electron-hole excitonic states are generally not expected to form with\ncharges of negative effective mass. We identify such excitons in a single layer\nof the semiconductor WSe2, where they give rise to narrow-band upconverted\nphotoluminescence in the UV, at an energy of 1.66 eV above the first band-edge\nexcitonic transition. Negative band curvature and strong electron-phonon\ncoupling result in a cascaded phonon progression with equidistant peaks in the\nphotoluminescence spectrum, resolvable to ninth order. Ab initio GW-BSE\ncalculations with full electron-hole correlations unmask and explain the\nadmixture of upper conduction-band states to this complex many-body excitation:\nan optically bright, bound exciton in resonance with the semiconductor\ncontinuum. This exciton is responsible for atomic-like quantum-interference\nphenomena such as electromagnetically induced transparency. Since band\ncurvature can be tuned by pressure or strain, synthesis of exotic\nquasiparticles such as flat-band excitons with infinite reduced mass becomes\nfeasible."
    },
    {
        "anchor": "Coulomb drag in graphene - boron nitride heterostructures: the effect of\n  virtual phonon exchange: For a system of two spatially separated monoatomic graphene layers\nencapsulated in hexagonal boron nitride, we consider the drag effect between\ncharge carriers in the Fermi liquid regime. Commonly, the phenomenon is\ndescribed in terms of an interlayer Coulomb interaction. We show that if an\nadditional electron - electron interaction via exchange of virtual substrate\nphonons is included in the model, the predicted drag resistivity is modified\nconsiderably at temperatures above 150 K. The anisotropic crystal structure of\nboron nitride, with strong intralayer and comparatively weak interlayer bonds,\nis found to play an important role in this effect.",
        "positive": "Charge-Resistance Approach to Benchmarking Performance of Beyond-CMOS\n  Information Processing Devices: Multiple beyond-CMOS information processing devices are presently under\nactive research and require methods of benchmarking them. A new approach for\ncalculating the performance metric, energy-delay product, of such devices is\nproposed. The approach involves estimating the device properties of resistance\nand switching charge, rather than dynamic evolution characteristics, such as\nswitching energy and time. Application of this approach to a wide class of\ncharge-based and non-charge based devices is discussed. The approach suggests\npathways for improving the performance of beyond-CMOS devices and a new\nrealistic limit for energy-delay product in terms of the Planks constant."
    },
    {
        "anchor": "Gate-tunable direct and inverse electrocaloric effect in trilayer\n  graphene: The electrocaloric (EC) effect is the reversible change in temperature and/or\nentropy of a material when it is subjected to an adiabatic electric field\nchange. Our tight-binding calculations linked to Fermi statistics, show that\nthe EC effect is sensitive to the stacking arrangement in trilayer graphene\n(TLG) structures connected to a heat source, and is produced by changes of the\nelectronic density of states (DOS) near the Fermi level when external gate\nfields are applied on the outer graphene layers. We demonstrate the AAA-stacked\nTLG presents an inverse EC response (cooling), whereas the EC effect in\nABC-stacked TLG remains direct (heating) regardless of the applied gate field\npotential strength. We reveal otherwise the TLG with Bernal-ABA stacking\ngeometry generates both the inverse and direct EC response in the same sample,\nassociated with a gate-dependent electronic entropy transition at finite\ntemperature. By varying the chemical potential to different Fermi levels, we\nfind maxima and minima of the DOS are located near the extremes of the\nelectronic entropy, which are correlated with sign changes in the differential\nentropy per particle, giving a particular experimentally measurable electronic\nentropy spectrum for each TLG geometry. The EC effect in quantum\ntwo-dimensional layered systems may bring a wide variety of prototype van der\nWaals materials that could be used as versatile platforms to controlling the\ntemperature in nanoscale electronic devices required in modern portable on-chip\ntechnologies.",
        "positive": "Frustrated magnetic interactions in a cyclacene crystal: We study the emergence of magnetism and its interplay with structural\nproperties in a two dimensional molecular crystal of cyclacenes, using density\nfunctional theory (DFT). Isolated cyclacenes with an even number of fused\nbenzenes host two unpaired electrons in two topological protected zero modes,\nat the top and bottom carbon rings that form the molecule. We show that, in the\ngas phase, electron repulsion promotes an open-shell singlet with strong\nintramolecular antiferromagnetic exchange. We consider a closed packing\ntriangular lattice crystal phase and we find a strong dependence of the band\nstructure and magnetic interactions on the rotation angle of the cyclacenes\nwith respect to the crystal lattice vectors. The orientational ground state\nmaximizes the intermolecular hybridization, yet local moments survive.\nIntermolecular exchange is computed to be antiferromagnetic, and DFT predicts a\nbroken symmetry $120^\\circ$ spin phase reflecting the frustration of the\nintermolecular spin coupling. Thus, the cyclacene crystal realizes a bilayer of\ntwo antiferromagnetically coupled S = 1/2 triangular lattices. Our results\nprovide a bottom-up route towards carbon based strongly correlated platforms in\ntwo dimensions."
    },
    {
        "anchor": "Skyrmion Lattice Collapse and Defect-Induced Melting in Chiral Magnetic\n  Films: Magnetic phase transitions are a test bed for exploring the physics of\nnon-equilibrium phenomena in condensed matter, which become even more complex\nwhen topological constraints are involved. In particular, the investigation of\nskyrmions and skyrmion lattices offers insight into fundamental processes of\ntopological-charge creation and annihilation upon changing the magnetic state.\nNonetheless, the exact physical mechanisms behind these phase transitions\nremain unresolved. Here, we have systematically compared ultra-thin films with\nisotropic and anisotropic Dzyaloshinskii-Moriya interactions (DMI),\ndemonstrating a nearly identical behavior in technologically relevant materials\nsuch as interfacial systems. We numerically show that in perfect systems\nskyrmion lattices can be inverted in a field-induced first-order phase\ntransition. The existence of even a single defect, however, replaces the\ninversion with a second-order phase transition of defect-induced lattice\nmelting. This radical change in the system's behavior from a first-order to a\nsecond-order phase transition signifies the importance of such an analysis for\nall realistic systems in order to correctly interpret experimental data. Our\nresults shed light on complex topological charge annihilation mechanisms that\nmediate transitions between magnetic states and pave the way for an\nexperimental realization of these phenomena.",
        "positive": "Spin Transfer Torque in Fully Insulating Magnetic Tunnel Junctions: Voltage-driven spin transfer torque in a magnetic tunnel junction comprising\nmagnetic insulating electrodes is studied theoretically. In contrast with the\nconventional magnetic tunnel junctions comprising transition metal\nferromagnets, the spin transfer torque presents unconventional bias\ndependencies, related to the presence of spin-dependent Fowler-Nordheim\ntunneling processes. In particular, we find that (i) the out-of-plane torque\ngenerally dominates the in-plane torque, (ii) out-of-plane torque and in-plane\ntorque are symmetric and asymmetric at low bias voltage, respectively, and\n(iii) both of torques show a dramatic enhancement at large bias voltage.\nMaterials consideration are discussed and we show that due to the low damping\nparameter expected in magnetic insulators a spin transfer torque can be\nexperimentally observed in such systems."
    },
    {
        "anchor": "Pinning theory of domain walls in helical magnets: The theory of elasticity and pinning of domain walls in helical magnets is\npresented. Domain walls perpendicular to the helical axis show non-local\nelasticity and are marginally pinned by local disorder. Weak anisotropy\ncombined with magnetic dilution leads however to a non-local bulk pinning\neffect. Domain walls with other orientations include generically vortex arrays,\nsimilar to type-II superconductors. Their pinning force is calculated as a\nfunction of wall orientation, pitch angle and impurity concentration. It is\nshown that metastable domains can vary between needle and pancake like shape.",
        "positive": "Hall conductivity in the cosmic defect and dislocation space-time: Influences of topological defect and dislocation on conductivity behavior of\ncharge carries in external electromagnetic fields are studied. Particularly the\nquantum Hall effect is investigated in detail. It is found that the nontrivial\ndeformations of spacetime due to topological defect and dislocation produce an\nelectric current at the leading order of perturbation theory. This current then\ninduces a deformation on the Hall conductivity. The corrections on the Hall\nconductivity depend on the external electric fields, the size of the sample and\nthe momentum of the particle."
    },
    {
        "anchor": "Nonreciprocal superposition state in antiferromagnetic optospintronics: The absence of net magnetization, which forbids any stray magnetic fields, is\none of the greatest advantages of antiferromagnets in device applications. In\nconventional antiferromagnets, however, spin current cannot be extracted\nwithout the aid of a static magnetic field. Here, we develop a theory of\nantiferromagnetic opto-spintronics to resolve this fundamental dilemma. By\ncoupling a linearly polarized photon and nonreciprocal magnon bands, we\nconstruct a superposition state of left- and right-handed magnon states with\nopposite group velocities. We numerically demonstrate that by using this\nsuperposition state, an antiferromagnetic spin current can be efficiently\ngenerated without a net magnetic field including net magnetization. We also\nfind that the breakdown of the superposition state induces the stripe\nsuperfluid phase of a two-component Bose-Einstein condensate. Our results lay\nthe foundation for manipulating the superposition states of emergent particles\nin devices.",
        "positive": "A green's function approach for surface state photoelectrons in\n  topological insulators: The topology of the surface electronic states is detected with photoemission.\nWe explain the photoemission from the topological surface state . This is done\nby identifying the effective coupling between surface electrons-photons and\nvacuum electrons. The effective electron photon coupling is given by $e\\tau^2$\nwhere $\\tau$ is the dimensionless tunneling amplitude of the zero mode surface\nstates to tunnel into the vacuum. We compute the polarization and intensity of\nthe emitted photoelectrons. We introduce a model which takes in account the\nDirac Hamiltonian for the surface electron to photons coupling and the\ntunneling of the zero mode into the vacuum.\n  Within the Green's function formalism we obtain exact results for the emitted\nPhotoelectrons to second order in the laser field. The number of the emitted\nphotoelectrons is sensitive to the laser coherent state intensity, the\npolarization is sensitive to the surface topology of the electronic states and\nthe incoming photon polarization. The calculation is performed for the helical,\nZeeman and warping case allowing to study spin textures."
    },
    {
        "anchor": "Non-Abelian phases, charge pumping, and quantum computation with\n  Josephson junctions: Non-Abelian geometric phases can be generated and detected in certain\nsuperconducting nanocircuits. Here we consider an example where the holonomies\nare related to the adiabatic charge dynamics of the Josephson network. We\ndemonstrate that such a device can be applied both for adiabatic charge pumping\nand as an implementation of a quantum computer.",
        "positive": "Efros-Shklovskii variable range hopping in reduced graphene oxide sheets\n  of varying carbon sp2 fraction: We investigate the low temperature electron transport properties of\nchemically reduced graphene oxide (RGO) sheets with different carbon sp2\nfractions of 55 to 80 %. We show that in the low bias (Ohmic) regime, the\ntemperature (T) dependent resistance (R) of all the devices follow\nEfros-Shklovskii variable range hopping (ES-VRH) R ~ exp[(T(ES)/T)^1/2] with\nT(ES) decreasing from 30976 to 4225 K and electron localization length\nincreasing from 0.46 to 3.21 nm with increasing sp2 fraction. From our data, we\npredict that for the temperature range used in our study, Mott-VRH may not be\nobserved even at 100 % sp2 fraction samples due to residual topological defects\nand structural disorders. From the localization length, we calculate a bandgap\nvariation of our RGO from 1.43 to 0.21 eV with increasing sp2 fraction from 55\nto 80 % which agrees remarkably well with theoretical prediction. We also show\nthat, in the high bias regime, the hopping is field driven and the data follow\nR ~ exp[(E(0)/E)^1/2] providing further evidence of ES-VRH."
    },
    {
        "anchor": "Direct observation of a magnetic field-induced Wigner crystal: Eugene Wigner predicted long ago that when the Coulomb interactions between\nelectrons become much stronger than their kinetic energy, electrons crystallize\ninto a closely packed lattice. A variety of two-dimensional systems have shown\nevidence for Wigner crystals; however, a spontaneously formed classical or\nquantum Wigner crystal (WC) has never been directly visualized. Neither the\nidentification of the WC symmetry nor direct investigation of its melting has\nbeen accomplished. Here we use high-resolution scanning tunneling microscopy\n(STM) measurements to directly image a magnetic field-induced electron WC in\nBernal-stacked bilayer graphene (BLG), and examine its structural properties as\na function of electron density, magnetic field, and temperature. At high fields\nand the lowest temperature, we observe a triangular lattice electron WC in the\nlowest Landau Level (LLL) of BLG. The WC possesses the expected lattice\nconstant and is robust in a range of filling factors between $\\nu\\sim$ 0.13 and\n$\\nu\\sim$ 0.38 except near fillings where it competes with fractional quantum\nHall (FQH) states. Increasing the density or temperature results in the melting\nof the WC into a liquid phase that is isotropic but has a modulated structure\ncharacterized by the WC's Bragg wavevector. At low magnetic fields, the WC\nunexpectedly transitions into an anisotropic stripe phase, which has been\ncommonly anticipated to form in higher LLs. Analysis of individual lattice\nsites reveals signatures that may be related to the quantum zero-point motion\nof electrons in the WC lattice.",
        "positive": "Probing quantum devices with radio-frequency reflectometry: Many important phenomena in quantum devices are dynamic, meaning that they\ncannot be studied using time-averaged measurements alone. Experiments that\nmeasure such transient effects are collectively known as fast readout. One of\nthe most useful techniques in fast electrical readout is radio-frequency\nreflectometry, which can measure changes in impedance (both resistive and\nreactive) even when their duration is extremely short, down to a microsecond or\nless. Examples of reflectometry experiments, some of which have been realised\nand others so far only proposed, include projective measurements of qubits and\nMajorana devices for quantum computing, real-time measurements of mechanical\nmotion and detection of non-equilibrium temperature fluctuations. However, all\nof these experiments must overcome the central challenge of fast readout: the\nlarge mismatch between the typical impedance of quantum devices (set by the\nresistance quantum) and of transmission lines (set by the impedance of free\nspace). Here, we review the physical principles of radio-frequency\nreflectometry and its close cousins, measurements of radio-frequency\ntransmission and emission. We explain how to optimise the speed and sensitivity\nof a radio-frequency measurement, and how to incorporate new tools such as\nsuperconducting circuit elements and quantum-limited amplifiers into advanced\nradio-frequency experiments. Our aim is three-fold: to introduce the readers to\nthe technique, to review the advances to date and to motivate new experiments\nin fast quantum device dynamics. Our intended audience includes\nexperimentalists in the field of quantum electronics who want to implement\nradio-frequency experiments or improve them, together with physicists in\nrelated fields who want to understand how the most important radio-frequency\nmeasurements work."
    },
    {
        "anchor": "Near-field heat transfer in a scanning thermal microscope: We present measurements of the near-field heat transfer between the tip of a\nthermal profiler and planar material surfaces under ultrahigh vacuum\nconditions. For tip-sample distances below 10-8 m our results differ markedly\nfrom the prediction of fluctuating electrodynamics. We argue that these\ndifferences are due to the existence of a material-dependent small length scale\nbelow which the macroscopic description of the dielectric properties fails, and\ndiscuss a corresponding model which yields fair agreement with the available\ndata. These results are of importance for the quantitative interpretation of\nsignals obtained by scanning thermal microscopes capable of detecting local\ntemperature variations on surfaces.",
        "positive": "Evaluation of Decoherence for Quantum Computing Architectures: Qubit\n  System Subject to Time-Dependent Control: We present an approach that allows quantifying decoherence processes in an\nopen quantum system subject to external time-dependent control. Interactions\nwith the environment are modeled by a standard bosonic heat bath. We develop\ntwo unitarity-preserving approximation schemes to calculate the reduced density\nmatrix. One of the approximations relies on a short-time factorization of the\nevolution operator, while the other utilizes expansion in terms of the\nsystem-bath coupling strength. Applications are reported for two illustrative\nsystems: an exactly solvable adiabatic model, and a model of a rotating-wave\nquantumcomputing gate function. The approximations are found to produce\nconsistent results at short and intermediate times."
    },
    {
        "anchor": "Spontaneous valley polarization of interacting carriers in a monolayer\n  semiconductor: We report magneto-absorption spectroscopy of gated WSe$_2$ monolayers in high\nmagnetic fields up to 60~T. When doped with a 2D Fermi sea of mobile holes,\nwell-resolved sequences of optical transitions are observed in both\n$\\sigma^\\pm$ circular polarizations, which unambiguously and separately\nindicate the number of filled Landau levels (LLs) in both $K$ and $K'$ valleys.\nThis reveals the interaction-enhanced valley Zeeman energy, which is found to\nbe highly tunable with hole density $p$. We exploit this tunability to align\nthe LLs in $K$ and $K'$, and find that the 2D hole gas becomes unstable against\nsmall changes in LL filling and can spontaneously valley-polarize. These\nresults cannot be understood within a single-particle picture, highlighting the\nimportance of exchange interactions in determining the ground state of 2D\ncarriers in monolayer semiconductors.",
        "positive": "Voltage controlled propagating spin waves on a perpendicularly\n  magnetized nanowire: We numerically and analytically investigate the voltage controlled spin wave\n(SW) propagations in a nanowire with locally manipulated perpendicular magnetic\nanisotropy (PMA) by applying an electric field. It is shown that the velocity\nand wavelength of the propagating SWs are tailored by the modified PMA, which\ncan be locally controlled by the external electric field. First, we observe a\nphase shift when the propagating SWs pass through the area of locally modified\nPMA. By introducing phase control of the SWs, we finally propose a three\nterminal SW device. Constructive/destructive interferences of two propagating\nSWs are controlled at the detecting area by the voltage controlled phase shift."
    },
    {
        "anchor": "Dynamics of coupled spins in quantum dots with strong spin-orbit\n  interaction: We investigated the time dependence of two-electron spin states in a double\nquantum dot fabricated in an InAs nanowire. In this system, spin-orbit\ninteraction has substantial influence on the spin states of confined electrons.\nPumping single electrons through a Pauli spin-blockade configuration allowed to\nprobe the dynamics of the two coupled spins via their influence on the pumped\ncurrent. We observed spin-relaxation with a magnetic field dependence different\nfrom GaAs dots, which can be explained by spin-orbit interaction. Oscillations\nwere detected for times shorter than the relaxation time, which we attribute to\ncoherent evolution of the spin states.",
        "positive": "Probing coherent Cooper pair splitting with cavity photons: This work discusses theoretically the behavior of a microwave cavity and a\nCooper pair beam splitter (CPS) coupled non-resonantly. The cavity frequency\npull is modified when the CPS is resonant with a microwave excitation. This\nprovides a direct way to probe the coherence of the Cooper pair splitting\nprocess. More precisely, the cavity frequency pull displays an anticrossing\nwhose specificities can be attributed unambiguously to coherent Cooper pair\ninjection. This work illustrates that microwave cavities represent a powerful\ntool to investigate current transport in complex nanocircuits."
    },
    {
        "anchor": "Nuclear Spin-Depleted, Isotopically Enriched 70Ge/28Si70Ge Quantum Wells: The p-symmetry of the hole wavefunction is associated with a weaker hyperfine\ninteraction as compared to electrons, thus making hole spin qubits attractive\ncandidates to implement long coherence quantum processors. However, recent\nstudies demonstrated that hole qubits in planar germanium (Ge) heterostructures\nare still very sensitive to nuclear spin bath. These observations highlight the\nneed to develop nuclear spin-free Ge qubits to suppress this decoherence\nchannel and evaluate its impact. With this perspective, this work demonstrates\nthe epitaxial growth of $^\\text{73}$Ge-depleted isotopically enriched\n$^\\text{70}$Ge/SiGe quantum wells. The growth was achieved by reduced pressure\nchemical vapor deposition using isotopically purified monogermane\n$^\\text{70}$GeH$_\\text{4}$ and monosilane $^\\text{28}$SiH$_\\text{4}$ with an\nisotopic purity higher than 99.9 $\\%$ and 99.99 $\\%$, respectively. The quantum\nwells consist of a series of $^\\text{70}$Ge/SiGe heterostructures grown on Si\nwafers using a Ge virtual substrate and a graded SiGe buffer layer. The\nisotopic purity is investigated using atom probe tomography following an\nanalytical procedure addressing the discrepancies in the isotopic content\ncaused by the overlap of isotope peaks in mass spectra. The nuclear spin\nbackground in the quantum wells was found to be sensitive to the growth\nconditions. The lowest concentration of nuclear spin-full isotopes\n$^\\text{73}$Ge and $^\\text{29}$Si in the heterostructure was established at\n0.01 $\\%$ in the Ge quantum well and SiGe barriers. The measured average\ndistance between nuclear spins reaches 3-4 nm in\n$^\\text{70}$Ge/$^\\text{28}$Si$^\\text{70}$Ge, which is an order of magnitude\nlarger than in natural Ge/SiGe heterostructures.",
        "positive": "Theory of two-photon absorption in poly(diphenyl) polyacetylenes: In this paper, we present a theoretical study of the nonlinear optical\nresponse of the newly discovered conjugated polymer poly(diphenyl)polyacetylene\n(PDPA). In particular, we compute the third-order nonlinear susceptibility\ncorresponding to two-photon absorption process in PDPA using: (a)\nindependent-particle H\\\"uckel model, and (b) using the correlated-electron\nPariser-Parr-Pople (P-P-P) model coupled with various configuration-interaction\nmethodologies such as the singles-configuration-interaction (SCI), the\nmulti-reference-singles-doubles CI (MRSDCI), and the quadruples-CI (QCI)\nmethod. At all levels of theory, the polymer is found to exhibit highly\nanisotropic nonlinear optical response, distributed over two distinct energy\nscales. The low-energy response is predominantly polarized in the conjugation\ndirection, and can be explained in terms of chain-based orbitals. The\nhigh-energy response of the polymer is found to be polarized perpendicular to\nthe conjugation direction, and can be explained in terms of orbitals based on\nthe side phenylene rings. Moreover, the intensity of the nonlinear optical\nresponse is also enhanced as compared to the corresponding polyenes, and can be\nunderstood in terms of reduced optical gap."
    },
    {
        "anchor": "Combination quantum oscillations in canonical single-band Fermi liquids: Chemical potential oscillations mix individual-band frequencies of the de\nHaas-van Alphen (dHvA) and Shubnikov-de Haas (SdH) magneto-oscillations in\ncanonical low-dimensional multi-band Fermi liquids. We predict a similar mixing\nin canonical single-band Fermi liquids, which Fermi-surfaces have two or more\nextremal cross-sections. Combination harmonics are analysed using a single-band\nalmost two-dimensional energy spectrum. We outline some experimental conditions\nallowing for resolution of combination harmonics.",
        "positive": "Magnus Induced Diode Effect for Skyrmions in Channels with Periodic\n  Potentials: Using a particle based model, we investigate the skyrmion dynamical behavior\nin a channel where the upper wall contains divots of one depth and the lower\nwall contains divots of a different depth. Under an applied driving force,\nskyrmions in the channels move with a finite skyrmion Hall angle that deflects\nthem toward the upper wall for $-x$ direction driving and the lower wall for\n$+x$ direction driving. When the upper divots have zero height, the skyrmions\nare deflected against the flat upper wall for $-x$ direction driving and the\nskyrmion velocity depends linearly on the drive. For $+x$ direction driving,\nthe skyrmions are pushed against the lower divots and become trapped, giving\nreduced velocities and a nonlinear velocity-force response. When there are\nshallow divots on the upper wall and deep divots on the lower wall, skyrmions\nget trapped for both driving directions; however, due to the divot depth\ndifference, skyrmions move more easily under $-x$ direction driving, and become\nstrongly trapped for $+x$ direction driving. The preferred $-x$ direction\nmotion produces what we call a Magnus diode effect since it vanishes in the\nlimit of zero Magnus force, unlike the diode effects observed for asymmetric\nsawtooth potentials. We show that the transport curves can exhibit a series of\njumps or dips, negative differential conductivity, and reentrant pinning due to\ncollective trapping events. We also discuss how our results relate to recent\ncontinuum modeling on a similar skyrmion diode system."
    },
    {
        "anchor": "Perspective on Coupled Colloidal Quantum Dot Molecules: Electronic coupling and hence hybridization of atoms serve as the basis for\nthe rich properties of the endless library of naturally occurring molecules.\nColloidal quantum dots (CQDs) manifesting quantum strong confinement, possess\natomic like characteristics with s and p electronic levels, which popularized\nthe notion of CQDs as artificial atoms. Continuing this analogy, when two atoms\nare close enough to form a molecule so that their orbitals start overlapping,\nthe orbitals' energies start to split into bonding and anti-bonding states made\nout of hybridized orbitals. The same concept is also applicable for two fused\ncore-shell nanocrystals in close proximity. Their band-edge states, which\ndictate the emitted photon energy, start to hybridize changing their electronic\nand optical properties. Thus, an exciting direction of artificial molecules\nemerges leading to a multitude of possibilities for creating a library of new\nhybrid nanostructures with novel optoelectronic properties with relevance\ntowards diverse applications including quantum technologies. In a model fused\ncore-shell homodimer molecule, the hybridization energy is strongly correlated\nwith the extent of structural continuity, the delocalization of the exciton\nwavefunction, and the barrier thickness as calculated numerically. The\nhybridization impacts the emitted photon statistics manifesting a faster\nradiative decay rate, photon bunching effect, and modified Auger recombination\npathway compared to the monomer artificial atoms. Future perspectives for the\nnanocrystals chemistry paradigm are highlighted.",
        "positive": "Shot noise fluctuations in disordered graphene nanoribbons near the\n  Dirac point: Random fluctuations of the shot-noise power in disordered graphene\nnanoribbons are studied. In particular, we calculate the distribution of the\nshot noise of nanoribbons with zigzag and armchair edge terminations. We show\nthat the shot noise statistics is different for each type of these two graphene\nstructures, which is a consequence of presence of different electron\nlocalizations: while in zigzag nanoribbons electronic edge states are Anderson\nlocalized, in armchair nanoribbons edge states are absent, but electrons are\nanomalously localized. Our analytical results are verified by tight binding\nnumerical simulations with random hopping elements, i.e., off diagonal\ndisorder, which preserves the symmetry of the graphene sublattices."
    },
    {
        "anchor": "Experimental realization of Laughlin quasiparticle interferometers: Laughlin quasiparticles are the elementary excitations of a highly-correlated\nfractional quantum Hall electron fluid. They have fractional charge and obey\nfractional statistics. The quasiparticles can propagate quantum-coherently in\nchiral edge channels, and constructively or destructively interfere. Unlike\nelectrons, the interference condition for Laughlin quasiparticles has a\nnon-vanishing statistical contribution that can be observed experimentally. Two\nkinds of interferometer devices have been realized. In the primary-filling\ninterferometer, the entire device has filling 1/3, and the e/3 edge channel\nquasiparticles encircle identical e/3 island quasiparticles. Here the flux\nperiod is h/e, same as for electrons, but the back-gate charge period is e/3.\nIn the second kind of interferometer, a lower density edge channel at filling\n1/3 forms around a higher density island at filling 2/5, so that e/3 edge\nquasiparticles encircle e/5 island quasiparticles. Here we observe\nsuperperiodic oscillations with 5h/e flux and 2e charge periods, both\ncorresponding to excitation of ten island quasiparticles. These periods can be\nunderstood as imposed by the anyonic braiding statistics of Laughlin\nquasiparticles.",
        "positive": "Electrically driven and electrically tunable quantum light sources: Compact and electrically controllable on-chip sources of indistinguishable\nphotons are desirable for the development of integrated quantum technologies.\nWe demonstrate that two quantum dot light emitting diodes (LEDs) in close\nproximity on a single chip can function as a tunable, all-electric quantum\nlight source. Light emitted by an electrically excited driving LED is used to\nexcite quantum dots the neighbouring diode. The wavelength of the quantum dot\nemission from the neighbouring driven diode is tuned via the quantum confined\nStark effect. We also show that we can electrically tune the fine structure\nsplitting."
    },
    {
        "anchor": "Spintronics and Magnon Bose-Einstein Condensation: Spintronics is the science and technology of electric control over spin\ncurrents in solid-state-based devices. Recent advances have demonstrated a\ncoupling between electronic spin currents in non-magnetic metals and magnons in\nmagnetic insulators. The coupling is due to spin transfer and spin pumping at\ninterfaces between the normal metals and magnetic insulators. In this Chapter,\nwe review these developments and the prospects they raise for electric control\nof quasi-equilibrium magnon Bose-Einstein condensates and spin superfluidity.",
        "positive": "Majorana-like zero modes in Kekul\u00e9 distorted sonic lattices: Topological phases have recently been realised in bosonic systems. The\nassociated boundary modes between regions of distinct topology have been used\nto demonstrate robust waveguiding, protected from defects by the topology of\nthe surrounding bulk. A related type of topologically protected state that is\nnot propagating but is bound to a defect has not been demonstrated to date in a\nbosonic setting. Here we demonstrate numerically and experimentally that an\nacoustic mode can be topologically bound to a vortex fabricated in a\ntwo-dimensional, Kekul\\'e-distorted triangular acoustic lattice. Such lattice\nrealises an acoustic analogue of the Jackiw-Rossi mechanism that topologically\nbinds a bound state in a p-wave superconductor vortex. The acoustic bound state\nis thus a bosonic \\edit{\\emph{analogue}} of Majorana bound state, \\edit{where\nthe two valleys replace particle and hole components}. We numerically show that\nit is topologically protected against arbitrary symmetry-preserving local\nperturbations, and remains pinned to the Dirac frequency of the unperturbed\nlattice regardless of parameter variations. We demonstrate our prediction\nexperimentally by 3D printing the vortex pattern in a plastic matrix and\nmeasuring the spectrum of the acoustic response of the device. Despite\nviscothermal losses, the measured topological resonance remains robust, with\nits frequency closely matching our simulations."
    },
    {
        "anchor": "Electronic properties of Janus black arsenic-phosphorus (b-AsP)\n  nanoribbons under transverse electric field: The electronic transport properties of Janus monolayer black arsenic\nphosphorus (b-AsP) nanoribbons have been investigated utilizing the\ntight-binding approach. The dependence of electronic structure on edge\nstructures is systematically investigated. (1,3)nb and (3,1)nb b-AsP\nnanoribbons exhibit flatter edge bands than zigzag and armchair counterparts.\nThe edge band of the armchair ones show double degeneracy. Further, the\ncalculated results show the band gap of the zigzag ribbon with different\nboundary morphology is widely tunable by transverse electric field. A critical\nelectric field can fully close the gap and induce a phase transition from a\nsemiconductor into a conductor. Our work suggests dynamically tunable bandgap\nin Janus b-AsP nanoribbons and reveals the potential of Janus b-AsP for\ntransmission devices.",
        "positive": "Ultimate accuracy of frequency to power conversion by single-electron\n  injection: We analyze theoretically the properties of the recently introduced and\nexperimentally demonstrated converter of frequency to power. The system is\ncomposed of a hybrid single-electron box with normal island and superconducting\nlead, and the detector of the energy flow using a thermometer on a normal metal\nbolometer. Here we consider its potential for metrology. The errors in power\narise mainly from inaccuracy of injecting electrons at the precise energy equal\nto the energy gap of the superconductor. We calculate the main systematic error\nin form of the excess average energy of the injected electrons and its\ncumulants, and due to sub-gap leakage. We demonstrate by analytic and numerical\ncalculations that the systematic error in detection can, in principle, be made\nmuch smaller than the injection errors, which also, with proper choice of\nsystem parameters, can be very small, < 1 %, at low enough temperature. Finally\nwe propose a simplified configuration for metrological purposes."
    },
    {
        "anchor": "Two-phonon Raman bands of bilayer graphene: revisited: We present complete calculations of the two-phonon Raman bands of bilayer\ngraphene, including all overtone and combination modes, within a\ndensity-functional tight-binding model. Based on our results, we assign\nunambiguously the observed two-phonon Raman bands to two-phonon modes, thus\nresolving the existing controversies. In particular, we show that both overtone\nand combination modes have essential contribution to the 2D band, bringing\nabout specific modifications of the band shape. We argue that a mid-range\ntwo-phonon Raman band, previously assigned to the 2ZO mode, should be assigned\nto the TOZO' mode. We find that the Raman band, usually assigned to the LOLA\nmode, has significant contribution from the TOZO mode. The predicted Raman\nbands can be used for assignment of the observed ones in the Raman spectra of\nbilayer graphene for the needs of sample characterization for future\ntechnological applications.",
        "positive": "Quantum rings with time dependent spin-orbit coupling: Rabi\n  oscillations, spintronic Schrodinger-cat states, and conductance properties: The strength of the (Rashba-type) spin-orbit coupling in mesoscopic\nsemiconductor rings can be tuned with external gate voltages. Here we consider\nthe case of a periodically changing spin-orbit interaction strength as induced\nby sinusoidal voltages. In a closed one dimensional quantum ring with weak\nspin-orbit coupling, Rabi oscillations are shown to appear. We find that the\ntime evolution of initially localized wave packets exhibits a series of\ncollapse and revival phenomena. Partial revivals -- that are typical in\nnonlinear systems -- are shown to correspond to superpositions of states\nlocalized at different spatial positions along the ring. These \"spintronic\nSchrodinger-cat sates\" appear periodically, and similarly to their counterparts\nin other physical systems, they are found to be sensitive to environment\ninduced disturbances. The time dependent spin transport problem, when leads are\nattached to the ring, is also solved. We show that the \"sideband currents\"\ninduced by the oscillating spin-orbit interaction strength can become the\ndominant output channel, even in the presence of moderate thermal fluctuations\nand random scattering events."
    },
    {
        "anchor": "Theory of inelastic scattering from magnetic impurities: We use the numerical renormalization group method tocalculate the single\nparticle matrix elements $\\cal T$ of the many body $T$-matrix of the conduction\nelectrons scattered by a magnetic impurity at T=0 temperature. Since $\\cal T$\ndetermines both the total and the elastic, spin-diagonal scattering cross\nsections, we are able to compute the full energy-, spin- and magnetic field\ndependence of the inelastic scattering cross section, $\\sigma_{\\rm\ninel}(\\omega)$. We find an almost linear frequency dependence of $\\sigma_{\\rm\ninel}(\\omega)$ below the Kondo temperature, $T_K$, which crosses over to a\n$\\sim \\omega^2$ behavior only at extremely low energies. Our method can be\ngeneralized to other quantum impurity models.",
        "positive": "Persistent Optical Gating of a Topological Insulator: Topological insulators (TIs) have attracted much attention due to their\nspin-polarized surface and edge states, whose origin in symmetry gives them\nintriguing quantum-mechanical properties. Robust control over the chemical\npotential of TI materials is important if these states are to become useful in\nnew technologies, or as a venue for exotic physics. Unfortunately, chemical\npotential tuning is challenging in TIs in part because the fabrication of\nelectrostatic top-gates tends to degrade material properties and the addition\nof chemical dopants or adsorbates can cause unwanted disorder. Here, we present\nan all-optical technique which allows persistent, bidirectional gating of a\n(Bi,Sb)2Te3 channel by optically manipulating the distribution of electric\ncharge below its interface with an insulating SrTiO3 substrate. In this fashion\nwe optically pattern p-n junctions in a TI material, which we subsequently\nimage using scanning photocurrent microscopy. The ability to dynamically write\nand re-write mesoscopic electronic structures in a TI may aid in the\ninvestigation of the unique properties of the topological insulating phase. The\noptical gating effect may be adaptable to other material systems, providing a\nmore general mechanism for reconfigurable electronics."
    },
    {
        "anchor": "Spin pinning and spin-wave dispersion in nanoscopic ferromagnetic\n  waveguides: Spin waves are investigated in Yttrium Iron Garnet (YIG) waveguides with a\nthickness of 39 nm and widths ranging down to 50 nm, i.e., with aspect ratios\nthickness over width approaching unity, using Brillouin Light Scattering\nspectroscopy. The experimental results are verified by a semi-analytical theory\nand micromagnetic simulations. A critical width is found, below which the\nexchange interaction suppresses the dipolar pinning phenomenon. This changes\nthe quantization criterion for the spin-wave eigenmodes and results in a\npronounced modification of the spin-wave characteristics. The presented\nsemi-analytical theory allows for the calculation of spin-wave mode profiles\nand dispersion relations in nano-structures.",
        "positive": "Asymmetric propagation of electronic wave function through molecular\n  bonding and anti-bonding states: Electron transport through molecular bridge shows novel quantum features.\nPropogation of electronic wave function through molecular bridge is completely\ndifferent than individual atomic bridge employed between two contacts. In case\nof molecular bridge electronic wave propagators interfere and effect conduction\nthrough molecular bonding and anti-bonding states.In the present work i showed\nthrough simple calculation that interference of electronic wave propagators\ncause asymmetric propagation of electronic wave through bonding and\nanti-bonding state. While for hydrogenic molecule these propagators interfere\ncompletely destructively for bonding state and constructively for anti-bonding\nstate, giving rise to only one peak in spectral function for anti- bonding\nstate."
    },
    {
        "anchor": "Size effect on the hysteresis characteristics of a system of interacting\n  core/shell nanoparticles: We have developed a model for the interacting ore/shell nanoparticles, which\nwe used to analyze the dependence of the coercive field Hc, the remanent\nsaturation magnetization Mrs and the satu- ration magnetization Ms on the\ninterfacial exchange interaction between the core and the shell, the size of\nthe nanoparticles and their interaction for Fe/Fe3O4 nanoparticles have been\ncarried out. It has been shown that the hysteresis characteristics increase\ntogether with the size of nanoparticles. Hc and Mrs are changing nonmonotonic\nwhen the constant interfacial exchange interaction changes from negative to\npositive values. In the system of core/shell nanoparticles, magnetic\ninteraction results in Hc and Mrs dropping, which was conformed by experiments.\nUsage: Secondary publications and information retrieval purposes.",
        "positive": "Quantum-Limited Position Detection and Amplification: A Linear Response\n  Perspective: Using standard linear response relations, we derive the quantum limit on the\nsensitivity of a generic linear-response position detector, and the noise\ntemperature of a generic linear amplifier. Particular emphasis is placed on the\ndetector's effective temperature and damping effects; the former quantity\ndirectly determines the dimensionless power gain of the detector. Unlike the\napproach used in the seminal work of Caves [Phys. Rev. D, 26, 1817 (1982)], the\nlinear-response approach directly involves the noise properties of the\ndetector, and allows one to derive simple necessary and sufficient conditions\nfor reaching the quantum limit. Our results have direct relevance to recent\nexperiments on nanoelectromechanical systems, and complement recent theoretical\nstudies of particular mesoscopic position detectors."
    },
    {
        "anchor": "On the Mechanical and Electronic Properties of Thiolated Gold\n  Nanocrystals: We present a quantitative exploration, combining experiment and simulation,\nof the mechanical and electronic properties, as well as the modifications\ninduced by an alkylthiolated coating, at the single NP level. We determine the\nresponse of the NPs to external pressure in a controlled manner by using an\natomic force microscope tip. We find a strong reduction of their Young modulus,\nas compared to bulk gold, and a significant influence of strain in the\nelectronic properties of the alkylthiolated NPs. Electron transport\nmeasurements of tiny molecular junctions (NP/alkylthiol/CAFM tip) show that the\neffective tunnelling barrier through the adsorbed monolayer strongly decreases\nwith increasing the applied load, which translates in a remarkable and\nunprecedented increase of the tunnel current. These observations are\nsuccessfully explained using simulations based on finite element analysis (FEA)\nand first-principles calculations that permit to consider the coupling between\nthe mechanical response of the system and the electric dipole variations at the\ninterface.",
        "positive": "Optical spin-wave detection beyond the diffraction limit: Spin waves are proposed as information carriers for next-generation computing\ndevices because of their low power consumption. Moreover, their wave-like\nnature allows for novel computing paradigms. Conventional methods to detect\nspin waves are based either on electrical induction, limiting the downscaling\nand efficiency complicating eventual implementation, or on light scattering,\nwhere the minimum detectable spin-wave wavelength is set by the wavelength of\nthe laser. In this Article we demonstrate magneto-optical detection of spin\nwaves beyond the diffraction limit using a metallic grating that selectively\nabsorbs laser light. Specifically, we demonstrate the detection of propagating\nspin waves with a wavelength of 700 nm using a diffraction-limited laser spot\nwith a size of 10 $\\mu$m in 20 nm thick Py strips. Additionally, we show that\nthis grating is selective to the wavelength of the spin wave, providing\nwavevector-selective spin-wave detection. This should open up new avenues\ntowards the integration of the burgeoning fields of photonics and magnonics,\nand aid in the optical detection of spin waves in the short-wavelength exchange\nregime for fundamental research."
    },
    {
        "anchor": "Shubnikov-de Haas oscillations in p and n-type topological insulator\n  (Bi$_{x}$Sb$_{1-x}$)$_{2}$Te$_{3}$: We show Shubnikov-de Haas oscillations in topological insulator\n(Bi$_{x}$Sb$_{1-x}$)$_{2}$Te$_{3}$ films whose carrier type is p-type (x =\n0.29, 0.34) and n-type (x = 0.42). The physical properties such as the Berry\nphase, mobility, and the scattering time are significantly changed by tuning\nthe Fermi-level position with the concentration x. The Landau-level fan diagram\nin the sample with x = 0.42 showed the $\\pi$ Berry phase and its mobility was\nas high as 17,000 cm$^{2}$/V/s, whereas the others had the 2$\\pi$ Berry phase\nand much lower mobility. This suggests that because the bulk band of the sample\nwith x = 0.42 does not cross the Fermi level, it becomes bulk insulating,\nresulting in the topological surface-state dominating transport. Thus, we can\nswitch sample properties from degenerate to bulk insulating by tuning the\nconcentration x, which is consistent with results of angle-resolved\nphotoemission spectroscopy.",
        "positive": "Interference in presence of Dissipation: We study a particle on a ring in presence of various dissipative\nenvironments. We develop and solve a variational scheme assuming low frequency\ndominance. We analyze our solution within a renormalization group (RG) scheme\nto all orders which reproduces a 2 loop RG for the Caldeira-Legget environment.\nIn the latter case the Aharonov-Bohm (AB) oscillation amplitude is exponential\nin -R^2 where R is the ring's radius. For either a charge or an electric dipole\ncoupled to a dirty metal we find that the metal induces dissipation, however\nthe AB amplitude is ~ R^{-2} for large R, as for free particles. Cold atoms\nwith a large electric dipole may show a crossover between these two behaviors."
    },
    {
        "anchor": "Temperature dependence of the energy band gap in ZrTe$_5$: implications\n  for the topological phase: Using Landau level spectroscopy, we determine the temperature dependence of\nthe energy band gap in zirconium pentatelluride (ZrTe$_5$). We find that the\nband gap reaches $E_g=(5 \\pm 1)$ meV at low temperatures and increases\nmonotonously when the temperature is raised. This implies that ZrTe$_5$ is a\nweak topological insulator, with non-inverted ordering of electronic bands in\nthe center of the Brillouin zone. Our magneto-transport experiments performed\nin parallel show that the resistivity anomaly in ZrTe$_5$ is not connected with\nthe temperature dependence of the band gap.",
        "positive": "Spin heat accumulation and spin-dependent temperatures in nanopillar\n  spin valves: Since the discovery of the giant magnetoresistance (GMR) effect the use of\nthe intrinsic angular momentum of the electrons has opened up new spin based\ndevice concepts. The two channel model of spin-up and spin-down electrons with\nspin-dependent conductivities very well describes spin and charge transport in\nsuch devices. In studies of the interaction between heat and spin transport, or\nspin caloritronics, until recently it was assumed that both spin species are\nalways at the same temperature. Here we report the observation of different\ntemperatures for the spin up (T_\\uparrow) and spin down (T_\\downarrow)\nelectrons in a nanopillar spin valve subject to a heat current. The weak\nrelaxation, especially at room temperature, of the spin heat accumulation (T_s\n= T_\\uparrow-T_\\downarrow) is essential for its detection in our devices. Using\n3D finite element modeling spin heat accumulation (SHA) values of 120 mK and\n350 mK are extracted at room temperature and 77 K, respectively, which is of\nthe order of 10% of the total temperature bias over the pillar. This technique\nuniquely allows the study of inelastic spin scattering at low energies and\nelevated temperatures, which is not possible by spectroscopic methods."
    },
    {
        "anchor": "Topological Insulators-Based Magnetic Heterostructure: The combination of magnetism and topology in magnetic topological insulators\n(MTIs) has led to unprecedented advancements of time reversal symmetry-breaking\ntopological quantum physics in the past decade. Compared with the uniform\nfilms, the MTI heterostructures provide a better framework to manipulate the\nspin-orbit coupling and spin properties. In this review, we summarize the\nfundamental mechanisms related to the physical orders host in\n(Bi,Sb)2(Te,Se)3-based hybrid systems. Besides, we provide an assessment on the\ngeneral strategies to enhance the magnetic coupling and spin-orbit torque\nstrength through different structural engineering approaches and effective\ninterfacial interactions. Finally, we offer an outlook of MTI\nheterostructures-based spintronics applications, particularly in view of their\nfeasibility to achieve room-temperature operation.",
        "positive": "Origin of Second Harmonic Generation from individual Silicon Nanowires: We investigate Second Harmonic Generation from individual silicon nanowires\nand study the influence of resonant optical modes on the far-field nonlinear\nemission. We find that the polarization of the Second Harmonic has a\nsize-dependent behavior and explain this phenomenon by a combination of\ndifferent surface and bulk nonlinear susceptibility contributions. We show that\nthe Second Harmonic Generation has an entirely different origin, depending on\nwhether the incident illumination is polarized parallel or perpendicularly to\nthe nanowire axis. The results open perspectives for further geometry-based\nstudies on the origin of Second Harmonic Generation in nanostructures of\nhigh-index centrosymmetric semiconductors."
    },
    {
        "anchor": "Electronic structure of a graphene superlattice with massive Dirac\n  fermions: We study the electronic and transport properties of a graphene-based\nsuperlattice theoretically by using an effective Dirac equation. The\nsuperlattice consists of a periodic potential applied on a single-layer\ngraphene deposited on a substrate that opens an energy gap of $2\\Delta$ in its\nelectronic structure. We find that extra Dirac points appear in the electronic\nband structure under certain conditions, so it is possible to close the gap\nbetween the conduction and valence minibands. We show that the energy gap $E_g$\ncan be tuned in the range $0\\leq E_g \\leq 2\\Delta$ by changing the periodic\npotential. We analyze the low energy electronic structure around the contact\npoints and find that the effective Fermi velocity in very anisotropic and\ndepends on the energy gap. We show that the extra Dirac points obtained here\nbehave differently compared to previously studied systems.",
        "positive": "Analysis of point defects in graphene using low dose scanning\n  transmission electron microscopy imaging and maximum likelihood\n  reconstruction: Freestanding graphene displays an outstanding resilience to electron\nirradiation at low electron energies. Point defects in graphene are, however,\nsubject to beam driven dynamics. This means that high resolution micrographs of\npoint defects, which usually require a high electron irradiation dose might not\nrepresent the intrinsic defect population. Here, we capture the inital defects\nformed by ejecting carbon atoms under electron irradiation, by imaging with\nvery low doses and subsequent reconstruction of the frequently occuring defects\nvia a maximum likelihood algorithm."
    },
    {
        "anchor": "Coupled system of electrons and exciton-polaritons: Screening, dynamical\n  effects, and superconductivity: Bose-Fermi systems such as mixtures of electrons with excitons or\nexciton-polaritons are extensively discussed as candidates to host a variety of\nintriguing phenomena, including polaron formation, drag effects, supersolidity,\nand superconductivity. In this work, assuming the strong-coupling regime\nbetween the semiconductor excitons and cavity photons, we develop the many-body\ntheory approach addressing the interplay of different types of interaction\namong various species in such a mixture, wherein we take into account dynamical\ndensity responses of both the Bose-condensed exciton-polaritons and the\ntwo-dimensional electron gas inside an optical microcavity. As was anticipated\npreviously, at high enough polariton densities the lower hybrid mode of the\nsystem's excitation spectrum acquires a roton minimum, making the system prone\nto superconducting pairing in the vicinity of the roton instability. We analyze\nthe possibility of polariton-BEC-mediated superconductivity in the electron gas\ntaking into account full momentum and frequency dependence of the gap, as well\nas in the Eliashberg approach where the momentum dependence is neglected, and\nin the Bardeen-Cooper-Schrieffer approach that discards the frequency\ndependence and dynamical effects. Considering the interaction screening in\nThomas-Fermi and in random-phase approximations, we estimate the critical\ntemperatures of superconductivity to be not larger than 0.1 K in the vicinity\nof instability. As possible realizations of the coupled polariton-electron\nsystem, semiconductor quantum wells and two-dimensional transition metal\ndichalcogenides are considered.",
        "positive": "Landau level evolution driven by band hybridization in mirror symmetry\n  broken ABA-stacked trilayer graphene: Layer stacking and crystal lattice symmetry play important roles in the band\nstructure and the Landau levels of multilayer graphene. ABA-stacked trilayer\ngraphene possesses mirror-symmetry-protected monolayer-like and bilayer-like\nband structures. Broken mirror symmetry by a perpendicular electric field\ntherefore induces hybridization between these bands and various quantum Hall\nphases emerge. We experimentally explore the evolution of Landau levels in\nABA-stacked trilayer graphene under electric field. We observe a variety of\nvalley and orbital dependent Landau level evolutions. These evolutions are\nqualitatively well explained by considering the hybridization between multiple\nLandau levels possessing close Landau level indices and the hybridization\nbetween every third Landau level orbitals due to the trigonal warping effect.\nThese observations are consistent with numerical calculations. The combination\nof experimental and numerical analysis thus reveals the entire picture of\nLandau level evolutions decomposed into the monolayer- and bilayer-like band\ncontributions in ABA-stacked trilayer graphene."
    },
    {
        "anchor": "Thermal conductivity reduction by acoustic Mie resonance in\n  nanoparticles: We evaluate the impact of acoustic Mie resonance in nanoparticles on the\nthermal conductivity of semiconductor and polymer composites. By appropriately\nchoosing the bulk modulus and density, and selecting the size of the\nnanoparticle to align the Mie resonances with the dominant portion of the\nthermal conductivity spectrum, we show that large reductions in thermal\nconductivity are achievable with dilute concentrations of nanoparticles. In\nsemiconductor alloys, where the spectral thermal conductivity is known, our\nmodel can explain the steep reductions in thermal conductivity observed\npreviously. However, the results of our effort to evaluate acoustic Mie\nresonance in polymer composites are inconclusive due to uncertainties in the\nspectral thermal conductivity. Acoustic Mie resonances can be useful for\nmaximizing ZT for thermoelectric applications, since a dilute loading of\nnanoparticles can reduce thermal conductivity with minimal impact on electrical\nconductivity.",
        "positive": "Comment on \"Gravitational Mass Carried by Sound Waves\": We comment on the paper A. Esposito, R. Krichevsky, and A. Nicolis,\n\"Gravitational Mass Carried by Sound Waves\", Phys. Rev. Lett. 122, 084501\n(2019). Our comment aims to avoid the confusion arisen in the scientific\ncommunity and beyond on how the result of Esposito et al. should be\ninterpreted."
    },
    {
        "anchor": "Diversity of behavior after collisions of Sn and Si nanoparticles found\n  using a new Density-Functional Tight-Binding model: We present a new approach to studying nanoparticle collisions using Density\nFunctional based Tight Binding (DFTB). A novel DFTB parameterisation has been\ndeveloped to study the collision process of Sn and Si nanoparticles (NPs) using\nMolecular Dynamics (MD). While bulk structures were used as training sets, we\nshow that our model is able to accurately reproduce the cohesive energy of the\nnanoparticles using Density Functional Theory (DFT) as a reference. A\nsurprising variety of phenomena are revealed for the Si/Sn nanoparticle\ncollisions, depending on the size and velocity of the collision: from\ncore-shell structure formation to bounce-off phenomena.",
        "positive": "Quantum Transport in Topological Semimetals under Magnetic Fields (II): We review our recent works on the quantum transport, mainly in topological\nsemimetals and also in topological insulators, organized according to the\nstrength of the magnetic field. At weak magnetic fields, we explain the\nnegative magnetoresistance in topological semimetals and topological insulators\nby using the semiclassical equations of motion with the nontrivial Berry\ncurvature. We show that the negative magnetoresistance can exist without the\nchiral anomaly. At strong magnetic fields, we establish theories for the\nquantum oscillations in topological Weyl, Dirac, and nodal-line semimetals. We\npropose a new mechanism of 3D quantum Hall effect, via the \"wormhole\" tunneling\nthrough the Weyl orbit formed by the Fermi arcs and Weyl nodes in topological\nsemimetals. In the quantum limit at extremely strong magnetic fields, we find\nthat an unexpected Hall resistance reversal can be understood in terms of the\nWeyl fermion annihilation. Additionally, in parallel magnetic fields,\nlongitudinal resistance dips in the quantum limit can serve as signatures for\ntopological insulators."
    },
    {
        "anchor": "Non-Markovian qubit dynamics in the presence of 1/f noise: Within the lowest-order Born approximation, we calculate the exact dynamics\nof a single qubit in the presence of 1/f noise, without making any Markov\napproximation. We show that the non-Markovian qubit time-evolution exhibits\nasymmetries and beatings that cannot be explained within a Markovian theory.\nThe present theory for 1/f noise is relevant for both spin- and superconducting\nqubit realizations in solid-state devices, where 1/f noise is ubiquitous.",
        "positive": "Electron Counting Statistics for Non-Additive Environments: Molecular electronics is a rapidly developing field focused on using\nmolecules as the structural basis for electronic components. It is common in\nsuch devices for the system of interest to couple simultaneously to multiple\nenvironments. Here we consider a model comprised of a double quantum dot (or\nmolecule) coupled strongly to vibrations and weakly to two electronic leads\nheld at arbitrary bias voltage. The strong vibrational coupling invalidates\ntreating the bosonic and electronic environments simply as acting additively,\nas would be the case in the weak coupling regime or for flat leads at infinite\nbias. Instead, making use of the reaction coordinate framework we incorporate\nthe dominant vibrational coupling effects within an enlarged system\nHamiltonian. This allows us to derive a non-additive form for the lead\ncouplings that accounts properly for the influence of strong and non-Markovian\ncoupling between the double dot system and the vibrations. Applying counting\nstatistics techniques we track electron flow between the double dot and the\nelectronic leads, revealing both strong-coupling and non-additive effects in\nthe electron current, noise and Fano factor."
    },
    {
        "anchor": "Electronically Guided Self Assembly within Quantum Corrals: A grand challenge of nanoscience is to master the control of structure and\nproperties in order to go beyond present day functionality. The creation of\nnanostructures via atom manipulation by means of a scanning probe represents\none of the great achievements of the nano era. Here we build on this\nachievement to self-assemble nanostructures within quantum corrals. The\nstructuring is guided by the quantum confinement of the electronic density of a\nsilver metallic substrate within the corrals. We experimentally demonstrate\ndifferent self-organized Gd atomic structures confined within 30-nm circular\nand triangular Fe quantum corrals. This approach enables the creation of model\nsystems to explore and understand new nanomaterials and device prototypes.",
        "positive": "Giant nonlinear Hall effect in twisted WSe$_2$: The recently discovered nonlinear Hall effect (NHE) in a few non-interacting\nsystems provides a novel mechanism to generate second harmonic electrical Hall\nsignals under time-reversal-symmetric conditions. Here, we introduce a new\napproach to engineering NHE by using twisted moir\\'e structures. We find that\nthe twisted WSe$_2$ bilayer exhibits a NHE when tuning the Fermi level to the\nmoir\\'e flat bands. Near half-filling of the first moir\\'e band, the nonlinear\nHall signal shows a sharp peak with the generation efficiency at least two\norders of magnitude larger than those in previous experiments. We propose that\nthe giant NHE and diverging generation efficiency originate from a\nmass-diverging type continuous Mott transition, which is evidenced by\nresistivity measurements. This work demonstrates not only how interaction\neffects can couple to Berry curvature dipoles to produce novel quantum\nphenomena, but also what NHE measurements can provide for developing a new tool\nto study the quantum criticality."
    },
    {
        "anchor": "Kramers Pairs of Majorana Fermions and Parafermions in Fractional\n  Topological Insulators: We propose a scheme based on topological insulators to generate Kramers pairs\nof Majorana fermions or parafermions in the complete absence of magnetic\nfields. Our setup consists of two topological insulators whose edge states are\nbrought close to an s-wave superconductor. The resulting proximity effect leads\nto an interplay between a non-local crossed Andreev pairing, which is dominant\nin the strong electron-electron interaction regime, and usual superconducting\npairing, which is dominant at large separation between the two topological\ninsulator edges. As a result, there are zero-energy bound states localized at\ninterfaces between spatial regions dominated by the two different types of\npairing. Due to the preserved time-reversal symmetry, the bound states come in\nKramers pairs. If the topological insulators carry fractional edge states, the\nzero-energy bound states are parafermions, otherwise, they are Majorana\nfermions.",
        "positive": "Information about the Integer Quantum Hall Transition Extracted from the\n  Autocorrelation Function of Spectral Determinants: The Autocorrelation function of spectral determinants (ASD) is used to probe\nthe sensitivity of a two-dimensional disordered electron gas to the system's\nsize L.\n  For weak magnetic fields ASD is shown to depend only trivially on L, which is\na strong indication that all states are localized.\n  From nontrivial dependence of ASD on L for infinite L at a Hall conductance\nof 1/2 e^2/h we deduce the existence of critical wave functions at this point,\nas long as the disorder strength does not exceed a critical value."
    },
    {
        "anchor": "Method of Collective Degrees of Freedom in Spin Coherent State Path\n  Integral: We present a detailed field theoretic description of those collective degrees\nof freedom (CDF) which are relevant to study macroscopic quantum dynamics of a\nquasi-one-dimensional ferromagnetic domain wall. We apply spin coherent state\npath integral (SCSPI) in the proper discrete time formalism (a) to extract the\nrelevant CDF's, namely, the center position and the chirality of the domain\nwall, which originate from the translation and the rotation invariances of the\nsystem in question, and (b) to derive effective action for the CDF's by\nelimination of environmental zero-modes with the help of the {\\it Faddeev-Popov\ntechnique}. The resulting effective action turns out to be such that both the\ncenter position and the chirality can be formally described by boson coherent\nstate path integral. However, this is only formal; there is a subtle departure\nfrom the latter.",
        "positive": "Graphene Transport Mediated by Micropatterned Substrates: Engineered substrates offer a promising avenue towards graphene devices\nhaving tunable properties. In particular, topographically patterned substrates\ncan expose unique behavior due to their ability to induce local variations in\nstrain and electrostatic doping. However, to explore the range of possible\nscience and applications, it is important to create topographic substrates\nwhich both have tunable features and are suitable for transport measurements.\nIn this Letter we describe the fabrication of tunable, topographically\npatterned substrates suitable for transport measurements. We report both\noptical and transport measurements of graphene devices fabricated on these\nsubstrates, and demonstrate characteristic strain and local doping behavior\ninduced by the topographic features."
    },
    {
        "anchor": "Quantum Mechanics of Spin Transfer in Ferromagnetic Multilayers: We use a quantum mechanical treatment of a ballistic spin current to describe\nnovel aspects of spin transfer to a ferromagnetic multilayer. We demonstrate\nquantum phenomena from spin transmission resonance (STR) to magnetoelectric\nspin echo (MESE), depending on the coupling between the magnetic moments in the\nferromagnetic thin films. Our calculation reveals new channels through which\nthe zero spin transfer occurs in multilayers: the STR and MESE. We also\nillustrate that counter-intuitively, a negative spin torque can act initially\non the second moment in a bilayer system.",
        "positive": "Ultrafast strong-field absorption in gapped graphene: We study theoretically the strong-field absorption of an ultrafast optical\npulse by a gapped graphene monolayer. At low field amplitudes, the absorbance\nin the pristine graphene is equal to the universal value of $2.3$ percent.\nAlthough the ultrafast optical absorption for low field amplitudes is\nindependent of the polarization, linear or circular, of the applied optical\npulse, for high field amplitudes, the absorption strongly depends on the pulse\npolarization. For a linearly polarized pulse, the optical absorbance is\nsaturated at the value of $\\approx 1.4$ percent for the pulse's amplitude of\n$\\geq 0.4~\\mathrm{V/\\AA}$, but no such saturation is observed for a circularly\npolarized pulse. For the gapped graphene, the absorption of a linearly\npolarized pulse has a weak dependence on the bandgap, while for a circularly\npolarized pulse, the absorption is very sensitive to the bandgap. %Opening a\nbandgap in graphene by placing in on, for example, SiC substrate strongly\nmodify the ultrafast absorption at small field amplitudes."
    },
    {
        "anchor": "Light-induced long-ranged disorder effect in ultra-dilute\n  two-dimensional holes in GaAs heterojunction-insulated-gate\n  field-effect-transistors: Comparing the results of transport measurements of strongly correlated\ntwo-dimensional holes in a GaAs heterojunction-insulated-gate\nfield-effect-transistor obtained before and after a brief photo-illumination,\nthe light-induced disorder is found to cause qualitative changes suggesting\naltered carrier states. For charge concentrations ranging from $3\\times10^{10}$\n$cm^{-2}$ down to $7\\times10^{8}$ cm$^{-2}$, the post-illumination hole\nmobility exhibits a severe suppression for charge densities below\n$2\\times10^{10}$ cm$^{-2}$, while almost no change for densities above. The\nlong-ranged nature of the disorder is identified. The temperature dependence of\nthe conductivity is also drastically modified by the disorder reconfiguration\nfrom being nonactivated to activated.",
        "positive": "Tunable terahertz reflection of graphene via ionic liquid gating: We report a highly efficient tunable THz reflector in graphene. By applying a\nsmall gate voltage (up to 3 V), the reflectance of graphene is modulated from a\nminimum of 0.79% to a maximum of 33.4% using graphene/ionic liquid structures\nat room temperature, and the reflection tuning is uniform within a wide\nspectral range (0.1 - 1.5 THz). Our observation is explained by the Drude\nmodel, which describes the THz wave-induced intraband transition in graphene.\nThis tunable reflectance of graphene may contribute to broadband THz mirrors,\ndeformable THz mirrors, variable THz beam splitters and other optical\ncomponents."
    },
    {
        "anchor": "Quantum simulation of the tricritical Ising model in tunable Josephson\n  junction ladders: Modern hybrid superconductor-semiconductor Josephson junction arrays are a\npromising platform for analog quantum simulations. Their controllable and\nnon-sinusoidal energy/phase relation opens the path to implement nontrivial\ninteractions and study the emergence of exotic quantum phase transitions. Here,\nwe propose the analysis of an array of hybrid Josephson junctions defining a\n2-leg ladder geometry for the quantum simulation of the tricritical Ising phase\ntransition. This transition provides the paradigmatic example of minimal\nconformal models beyond Ising criticality and its excitations are intimately\nrelated with Fibonacci non-Abelian anyons and topological order in two\ndimensions. We study this superconducting system and its thermodynamic phases\nbased on bosonization and matrix-product-states techniques. Its effective\ncontinuous description in terms of a three-frequency sine-Gordon quantum field\ntheory suggests the presence of the targeted tricritical point and the\nnumerical simulations confirm this picture. Our results indicate which\nexperimental observables can be adopted in realistic devices to probe the\nphysics and the phase transitions of the model. Additionally, our proposal\nprovides a useful one-dimensional building block to design exotic topological\norder in two-dimensional scalable Josephson junction arrays.",
        "positive": "Evidence for an Anisotropic State of Two-Dimensional Electrons in High\n  Landau Levels: Magneto-transport experiments on high mobility two-dimensional electron gases\nin GaAs/AlGaAs heterostructures have revealed striking anomalies near\nhalf-filling of several spin-resolved, yet highly excited, Landau levels. These\nanomalies include strong anisotropies and non-linearities of the longitudinal\nresistivity rho_xx which commence only below about 150mK. These phenomena are\nnot seen in the ground or first excited Landau level but begin abruptly in the\nthird level. Although their origin remains unclear, we speculate that they\nreflect the spontaneous development of a generic anisotropic many-electron\nstate."
    },
    {
        "anchor": "Localized bright luminescence of indirect excitons and trions in\n  MoSe$_2$/WSe$_2$ van der Waals heterostructure: Indirect excitons (IX) in semiconductor heterostructures are bosons, which\ncan cool below the temperature of quantum degeneracy and can be effectively\ncontrolled by voltage and light. IX quantum Bose gases and IX devices were\nexplored in GaAs heterostructures where an IX range of existence is limited to\nlow temperatures due to low IX binding energies. IXs in van der Waals\ntransition-metal dichalcogenide (TMD) heterostructures are characterized by\nlarge binding energies giving the opportunity for exploring excitonic quantum\ngases and for creating excitonic devices at high temperatures. TMD\nheterostructures also offer a new platform for studying single-exciton\nphenomena and few-particle complexes. In this work, we present studies of IXs\nin MoSe$_2$/WSe$_2$ heterostructures and report on two IX luminescence lines\nwhose energy splitting and temperature dependence identify them as neutral and\ncharged IXs. The experimentally found binding energy of the indirect charged\nexcitons, i.e. indirect trions, is close to the calculated binding energy of 28\nmeV for negative indirect trions in TMD heterostructures [Deilmann, Thygesen,\nNano Lett. 18, 1460 (2018)]. We also report on the realization of IXs with a\nluminescence linewidth reaching 4~meV at low temperatures. An enhancement of IX\nluminescence intensity and the narrow linewidth are observed in localized\nspots.",
        "positive": "The trion: two electrons plus one hole versus one electron plus one\n  exciton: We first show that, for problems dealing with trions, it is totally hopeless\nto use the standard many-body description in terms of electrons and holes and\nits associated Feynman diagrams. We then show how, by using the description of\na trion as an electron interacting with an exciton, we can obtain the trion\nabsorption through far simpler diagrams, written with electrons and\n\\emph{excitons}. These diagrams are quite novel because, for excitons being not\nexact bosons, we cannot use standard procedures designed to deal with\ninteracting true fermions or true bosons. A new many-body formalism is\nnecessary to establish the validity of these electron-exciton diagrams and to\nderive their specific rules. It relies on the ``commutation technique'' we\nrecently developed to treat interacting close-to-bosons. This technique\ngenerates a scattering associated to direct Coulomb processes between electrons\nand excitons and a dimensionless ``scattering'' associated to electron exchange\ninside the electron-exciton pairs -- this ``scattering'' being the original\npart of our many-body theory. It turns out that, although exchange is crucial\nto differentiate singlet from triplet trions, this ``scattering'' enters the\nabsorption explicitly when the photocreated electron and the initial electron\nhave the same spin -- \\emph{i}. \\emph{e}., when triplet trions are the only\nones created -- \\emph{but not} when the two spins are different, although\ntriplet trions are also created in this case. The physical reason for this\nrather surprising result will be given."
    },
    {
        "anchor": "Approaching a fully-polarized state of nuclear spins in a semiconductor\n  quantum dot: Magnetic noise of atomic nuclear spins is a major problem for solid state\nspin qubits. Highly-polarized nuclei would not only overcome this obstacle, but\nalso make nuclear spins a useful quantum information resource. However,\nachieving sufficiently high nuclear polarizations has remained an evasive goal.\nHere we implement a nuclear spin polarization protocol which combines strong\noptical pumping and fast electron tunneling. Polarizations well above 95% are\ngenerated in GaAs semiconductor quantum dots on a timescale of 1 minute. The\ntechnique is compatible with standard quantum dot device designs, where\nhighly-polarized nuclear spins can simplify implementations of quantum bits and\nmemories, as well as offer a testbed for studies of many-body quantum dynamics\nand magnetism.",
        "positive": "Quantum computing with spin qubits in semiconductor structures: We survey recent work on designing and evaluating quantum computing\nimplementations based on nuclear or bound-electron spins in semiconductor\nheterostructures at low temperatures and in high magnetic fields. General\noverview is followed by a summary of results of our theoretical calculations of\ndecoherence time scales and spin-spin interactions. The latter were carried out\nfor systems for which the two-dimensional electron gas provides the dominant\ncarrier for spin dynamics via exchange of spin-excitons in the integer quantum\nHall regime."
    },
    {
        "anchor": "Magnetization in narrow ribbons: curvature effects: A ribbon is a surface swept out by a line segment turning as it moves along a\ncentral curve. For narrow magnetic ribbons, for which the length of the line\nsegment is much less than the length of the curve, the anisotropy induced by\nthe magnetostatic interaction is biaxial, with hard axis normal to the ribbon\nand easy axis along the central curve. The micromagnetic energy of a narrow\nribbon reduces to that of a one-dimensional ferromagnetic wire, but with\ncurvature, torsion and local anisotropy modified by the rate of turning. These\ngeneral results are applied to two examples, namely a helicoid ribbon, for\nwhich the central curve is a straight line, and a M\\\"obius ribbon, for which\nthe central curve is a circle about which the line segment executes a\n$180^\\circ$ twist. In both examples, for large positive tangential anisotropy,\nthe ground state magnetization lies tangent to the central curve. As the\ntangential anisotropy is decreased, the ground state magnetization undergoes a\ntransition, acquiring an in-surface component perpendicular to the central\ncurve. For the helicoid ribbon, the transition occurs at vanishing anisotropy,\nbelow which the ground state is uniformly perpendicular to the central curve.\nThe transition for the M\\\"obius ribbon is more subtle; it occurs at a positive\ncritical value of the anisotropy, below which the ground state is nonuniform.\nFor the helicoid ribbon, the dispersion law for spin wave excitations about the\ntangential state is found to exhibit an asymmetry determined by the geometric\nand magnetic chiralities.",
        "positive": "Semianalytical quantum model for graphene field-effect transistors: We develop a semianalytical model for monolayer graphene field-effect\ntransistors in the ballistic limit. Two types of devices are considered: in the\nfirst device, the source and drain regions are doped by charge transfer with\nSchottky contacts, while, in the second device, the source and drain regions\nare doped electrostatically by a back gate. The model captures two important\neffects that influence the operation of both devices: (i) the finite density of\nstates in the source and drain regions, which limits the number of states\navailable for transport and can be responsible for negative output differential\nresistance effects, and (ii) quantum tunneling across the potential steps at\nthe source-channel and drain-channel interfaces. By comparison with a\nself-consistent non-equilibrium Green's function solver, we show that our model\nprovides very accurate results for both types of devices, in the bias region of\nquasi-saturation as well as in that of negative differential resistance."
    },
    {
        "anchor": "Optimizing Broadband Terahertz Modulation with Hybrid\n  Graphene/Metasurface Structures: We demonstrate efficient terahertz (THz) modulation by coupling graphene\nstrongly with a broadband THz metasurface device. This THz metasurface, made of\nperiodic gold slit arrays, shows near unity broadband transmission, which\narises from coherent radiation of the enhanced local-field in the slits.\nUtilizing graphene as an active load with tunable conductivity, we can\nsignificantly modify the local-field enhancement and strongly modulate the THz\nwave transmission. This hybrid device also provides a new platform for future\nnonlinear THz spectroscopy study of graphene.",
        "positive": "Anisotropic profiles in the spin polarization of multichannel\n  semiconductor rings with Rashba spin orbit coupling: We investigate the spin accumulation effect in eccentric semiconductor\nmultichannel rings with Rashba spin-orbit interaction and threaded by a\nmagnetic flux. Due to the finite eccentricity, the spin polarization induced at\nthe borders of the sample is anisotropic and exhibits different patterns and\nintensities at specific angular directions. This effect, reminiscent of the\nspin polarization drift induced by the application of an in plane electric\nfield, could be used to manipulate and functionalize the spin polarization in\nelectronic nanorings."
    },
    {
        "anchor": "Magnetocaloric effect in multilayers studied by membrane-based\n  calorimetry: We study magnetic multilayers, incorporating dilute ferromagnetic spacers\nbetween strongly-ferromagnetic layers exhibiting a proximity-enhanced\nmagnetocaloric effect. Using magnetometry and direct measurements of the\nadiabatic temperature change based on a nanomembrane-calorimetry, we find that\nthe magnetocaloric effect in the studied multilayer is indeed enhanced compared\nto that in the bulk spacer material. We develop a phenomenological numerical\nmodel of the studied trilayer and find that a long-range exchange interaction\nthrough the weakly-ferromagnetic spacer is required to adequately describe the\nmagnetic and magnetocaloric properties of the system.",
        "positive": "RKKY interaction in graphene: We consider RKKY interaction between two magnetic impurities in graphene. The\nconsideration is based on the perturbation theory for the thermodynamic\npotential in the imaginary time representation. We analyze the symmetry of the\nRKKY interaction on the bipartite lattice at half filling. Our analytical\ncalculation of the interaction is based on direct evaluation of real space spin\nsusceptibility. We show in the Appendix, added to the published version, that\nthe approach can be easily generalized to the case of finite temperature."
    },
    {
        "anchor": "Investigation of electron and phonon transport in Bi-doped CaMnO$_3$ for\n  thermoelectric applications: Electron and phonon transports in CaMnO3 and its Bi-doped counterpart,\nBi0.03Ca0.97MnO3, are investigated by thermoelectric transport measurements,\nRaman spectroscopy, and first-principles calculations. In particular, we focus\non CaMnO3 and Bi0.03Ca0.97MnO3's electronic structures, temperature-dependent\nelectron and phonon lifetimes, and their sound velocities. We find that the\nanti-ferromagnetic insulator CaMnO3 breaks the Wiedemann-Franz (WF) law with\nthe Lorenz number reaching four times that of ordinary metals at room\ntemperature. Bismuth doping reduces both the electrical resistivity and the\nSeebeck coefficient of CaMnO3, thus it recovers the WF law behavior. Raman\nspectroscopy confirms that Bi0.03Ca0.97MnO3 has a lower Debye frequency as well\nas a shorter phonon lifetime. As a result, Bi0.03Ca0.97MnO3 exhibits superior\nthermoelectric properties over the pristine CaMnO3 due to the lower thermal\nconductivity and electronic resistivity.",
        "positive": "Edge Channels of Broken-Symmetry Quantum Hall States in Graphene probed\n  by Atomic Force Microscopy: The quantum Hall (QH) effect, a topologically non-trivial quantum phase,\nexpanded and brought into focus the concept of topological order in physics.\nThe topologically protected quantum Hall edge states are of crucial importance\nto the QH effect but have been measured with limited success. The QH edge\nstates in graphene take on an even richer role as graphene is distinguished by\nits four-fold degenerate zero energy Landau level (zLL), where the symmetry is\nbroken by electron interactions on top of lattice-scale potentials but has\neluded spatial measurements. In this report, we map the quantum Hall\nbroken-symmetry edge states comprising the graphene zLL at integer filling\nfactors of $\\nu=0,\\pm 1$ across the quantum Hall edge boundary using atomic\nforce microscopy (AFM). Measurements of the chemical potential resolve the\nenergies of the four-fold degenerate zLL as a function of magnetic field and\nshow the interplay of the moir\\'e superlattice potential of the graphene/boron\nnitride system and spin/valley symmetry-breaking effects in large magnetic\nfields."
    },
    {
        "anchor": "Linearly controlled arrangement of $^{13}$C isotopes in single-wall\n  carbon nanotubes: The growth of single wall carbon nanotubes (SWCNT) inside host SWCNTs remains\na compelling alternative to the conventional catalyst induced growth processes.\nIt not only provides a catalyst free process but the ability to control the\nconstituents of the inner tube if appropriate starting molecules are used. We\nreport herein the growth of inner SWCNTs from $^{13}$C labeled toluene and\nnatural carbon C$_{60}$. The latter molecule is essentially a stopper which\nacts to retain the smaller toluene. The Raman spectrum of the inner nanotubes\nis anomalous as it contains a highly isotope shifted \"tail\", which cannot be\nexplained by assuming a homogeneous distribution of the isotopes.\n{\\color{black}Semi-empirical} calculations of the Raman modes indicate that\nthis unsual effect is explicable if small clusters of $^{13}$C are assumed.\nThis indicates the absence of carbon diffusion during the inner tube growth.\nWhen combined with appropriate molecular recognition, this may enable a\nmolecular engineering of the atomic and isotope composition of the inner tubes.",
        "positive": "Nematic and smectic stripe phases and stripe-SkX transformations: Based on the findings of stripe skyrmions and the metastability of a state of\nan arbitrary number of skyrmions, precisely controlled manipulation of stripe\nskyrmions in pre-designed structures and mutual transformation between helical\nstates and skyrmion crystals (SkXs) are demonstrated in chiral magnetic films.\nAs a proof of the concept, we show how to use patterned magnetic fields and\nspin-transfer torques (STTs) to generate nematic and smectic stripe phases, as\nwell as \"UST\" mosaic from three curved stripe skyrmions. Cutting one stripe\ninto many pieces and coalescing several skyrmions into one by various external\nfields are good ways to transform helical states and SkXs from each other."
    },
    {
        "anchor": "Carrier Density and Magnetism in Graphene Zigzag Nanoribbons: The influence of carrier density on magnetism in a zigzag graphene nanoribbon\nis studied in a $\\pi$-orbital Hubbard-model mean-field approximation.\nDepartures from half-filling alter the magnetism, leading to states with charge\ndensity variation across the ribbon and parallel spin-alignment on opposite\nedges. Finite carrier densities cause the spin-density near the edges to\ndecrease steadily, leading eventually to the absence of magnetism. At low\ndoping densities the system shows a tendency to multiferroic order in which\nedge charges and spins are simultaneously polarized.",
        "positive": "Gateway state-mediated, long-range tunnelling in molecular wires: If the factors controlling the decay in single-molecule electrical\nconductance G with molecular length L could be understood and controlled, then\nthis would be a significant step forward in the design of high-conductance\nmolecular wires. For a wide variety of molecules conducting by phase coherent\ntunneling, conductance G decays with length following the relationship G =\nAexp-\\b{\\eta}L. It is widely accepted that the attenuation coefficient \\b{\\eta}\nis determined by the position of the Fermi energy of the electrodes relative to\nthe energy of frontier orbitals of the molecular bridge, whereas the terminal\nanchor groups which bind to the molecule to the electrodes contribute to the\npre-exponential factor A. We examine this premise for several series of\nmolecules which contain a central conjugated moiety (phenyl, viologen or\n{\\alpha}-terthiophene) connected on either side to alkane chains of varying\nlength, with each end terminated by thiol or thiomethyl anchor groups. In\ncontrast with this expectation, we demonstrate both experimentally and\ntheoretically that additional electronic states located on thiol anchor groups\ncan significantly decrease the value of \\b{eta}, by giving rise to resonances\nclose to EF through coupling to the bridge moiety. This interplay between the\ngateway states and their coupling to a central conjugated moiety in the\nmolecular bridges creates a new design strategy for realising\nhigher-transmission molecular wires by taking advantage of the\nelectrode-molecule interface properties."
    },
    {
        "anchor": "Polarized photoluminescence and g-factor in an ensemble of quantum dots\n  in magnetic fields: In this paper, polarized photoluminescence caused by exciton\nquasi-equilibrium spin orientation on Zeeman sublevels in an ensemble of\nquantum dots of different sizes is theoretically studied. It is found that: (i)\nthe splitting of the photoluminescence bands in a magnetic field in an ensemble\nof quantum dots is several orders of magnitude larger than the Zeeman splitting\nof exciton levels in a single dot, (ii) the sign of the circular polarization\nof the photoluminescence changes along the contour of the bands, (iii) the\nchange of the sign of the polarization is associated with the change of the\nsign of the exciton g-factor. A universal formula for the dependence of the\nexciton g-factor on the quantum dot size is obtained. This dependence is valid\nfor both bulk material and nanostructures of different types and sizes.\nComparison of the results obtained with the experimentally measured data has\nbeen carried out.",
        "positive": "Enhancing Thermoelectric Properties Through a Three-Terminal Benzene\n  Molecule: The thermoelectric transport through a benzene molecule with three metallic\nterminals is discussed. Using general local and non-local transport\ncoeffcients, we investigated different conductance and thermopower coefficients\nwithin the linear response regime. Based on the Onsager coefficient which\ndepend on the number of terminal efficiencies, efficiency at maximum power is\nalso studied. In the three-terminal set up with tuning temperature differences,\na great enhancement of the figure of merit is observed. Results also show that\nthe third terminal model can be useful to improve the efficiency at maximum\noutput power compared to the two-terminal model."
    },
    {
        "anchor": "Coexistence of parallel and series current paths in parallel-coupled\n  double quantum dots in nonlinear transport regime: We investigated the electron transport properties of parallel-coupled double\nquantum dot (DQD) devices under magnetic fields. When a low magnetic field was\napplied, electron tunneling through parallel-coupled DQDs was observed. Under a\nhigh magnetic field, we observed both electron tunneling through parallel- and\nseries-coupled DQDs under nonlinear transport conditions. In addition, the\nPauli spin blockade was observed, indicating tunneling through the\nseries-coupled DQDs. We attribute these behaviors to the magnetic-field-induced\nchanges in the tunnel-couplings that allow the coexistence of the current paths\nof the parallel and series configurations.",
        "positive": "Very low shot noise in carbon nanotubes: We have performed noise measurements on suspended ropes of single wall carbon\nnanotubes (SWNT) between 1 and 300 K for different values of dc current through\nthe ropes. We find that the shot noise is suppressed by more than a factor 100\ncompared to the full shot noise 2eI. We have also measured an individual SWNT\nand found a level of noise which is smaller than the minimum expected. Another\nfinding is the very low level of 1/f noise, which is significantly lower than\nprevious observations. We propose two possible interpretations for this strong\nshot noise reduction: i) Transport within a rope takes place through a few\nnearly ballistic tubes within a rope and possibly involves non integer\neffective charges. ii) A substantial fraction of the tubes conduct with a\nstrong reduction of effective charge (by more than a factor 50)."
    },
    {
        "anchor": "Encyclopedia of emergent particles in three-dimensional crystals: The past decade has witnessed a surge of interest in exploring emergent\nparticles in condensed matter systems. Novel particles, emerged as excitations\naround exotic band degeneracy points, continue to be reported in real materials\nand artificially engineered systems, but so far, we do not have a complete\npicture on all possible types of particles that can be achieved. Here, via\nsystematic symmetry analysis and modeling, we accomplish a complete list of all\npossible particles in time reversal-invariant systems. This includes both\nspinful particles such as electron quasiparticles in solids, and spinless\nparticles such as phonons or even excitations in electric-circuit and\nmechanical networks. We establish detailed correspondence between the particle,\nthe symmetry condition, the effective model, and the topological character.\nThis obtained encyclopedia concludes the search for novel emergent particles\nand provides concrete guidance to achieve them in physical systems.",
        "positive": "Effective Medium Model for Graphene Superlattices with Electrostatic and\n  Magnetic Vector Potentials: In this article we develop an effective medium model to characterize the\nelectron wave propagation in graphene based nanostructures with an\nelectrostatic and magnetic vector potentials imposed on their surface. We use a\nnumerical algorithm to determine the effective medium parameters of the\nheterostructure and calculate the electronic band structure of the system. We\napply our formalism to analyze superlattices with solely a magnetic potential\nand reveal that the response of the structure remains reciprocal and is\ncharacterized by a decrease in charge carrier's velocity. We also study the\nresponse of superlattices with both potentials superimposed on graphene and\nshow that the response of the system becomes nonreciprocal with a dispersion\ncharacterized by a tilted Dirac cone. We demonstrate that it is possible to\nalternate between a type-I, type-II or type-III Dirac cones by properly tuning\nthe amplitude of the potentials."
    },
    {
        "anchor": "Dynamic enhancement of conductance in fractional quantum Hall\n  constriction: AC transformer action of a quantum point contact separating quantum Hall\nstates with distinct filling fractions $(\\nu_{1},\\nu_{2})$ is studied\ntheoretically. The AC gain ($g_{\\nu_{1},\\nu_{2}}(\\omega)$) of this setup is\nshown to exceed its DC bound ($g^{max}_{\\nu_{1},\\nu_{2}}(\\omega=0) =\n2\\,\\mathrm{max}\\lbrace\\nu_{1},\\nu_{2}\\rbrace/(\\nu_{1}+\\nu_{2})$) for a certain\nrange of frequency in the presence of appropriate inter-electron interactions\nowing to displacement current induced by the ambient gate electrodes. This\nsetup is also endowed with the unique possibility of having frequency tunable\nresonances and anti-resonances across the QPC.",
        "positive": "Weak Localization and Integer Quantum Hall Effect in a Periodic\n  Potential: We consider magnetotransport in a disordered two-dimensional electron gas in\nthe presence of a periodic modulation in one direction. Existing quasiclassical\nand quantum approaches to this problem account for Weiss oscillations in the\nresistivity tensor at moderate magnetic fields, as well as a strong\nmodulation-induced modification of the Shubnikov-de Haas oscillations at higher\nmagnetic fields. They do not account, however, for the operation at even higher\nmagnetic fields of the integer quantum Hall effect, for which quantum\ninterference processes are responsible. We then introduce a field-theory\napproach, based on a nonlinear sigma model, which encompasses naturally both\nthe quasiclassical and quantum-mechanical approaches, as well as providing a\nconsistent means of extending them to include quantum interference corrections.\nA perturbative renormalization-group analysis of the field theory shows how\nweak localization corrections to the conductivity tensor may be described by a\nmodification of the usual one-parameter scaling, such as to accommodate the\nanisotropy of the bare conductivity tensor. We also show how the two-parameter\nscaling, conjectured as a model for the quantum Hall effect in unmodulated\nsystems, may be generalized similarly for the modulated system. Within this\nmodel we illustrate the operation of the quantum Hall effect in modulated\nsystems for parameters that are realistic for current experiments."
    },
    {
        "anchor": "Hydrodynamic magnetoresistance in graphene Corbino devices: We study hydrodynamic electron magnetotransport in graphene devices. We show\nthat in these systems a distinct mechanism of magnetoresistance appears, which\nis absent in systems with Galilean-invariant electron liquid. The resulting\nmagnetoresistance depends on the intrinsic conductivity and viscosity of the\nelectron liquid, and becomes especially pronounced near charge neutrality. We\nobtain analytic expressions for magnetoransport coefficients of Corbino\ndevices, and obtain estimates for the electrical and thermal magnetoresistances\nfor monolayer and bilayer systems at charge neutrality. Magnetoresistance\nbecomes strong (of order 100%) at relatively weak fields, at which the kinetic\ncoefficients of the electron liquid are practically unaffected by the magnetic\nfield.",
        "positive": "Heterogeneous nucleation of catalyst-free InAs nanowires on silicon: We report on the heterogeneous nucleation of catalyst-free InAs nanowires on\nSi (111) substrates by chemical beam epitaxy. We show that nanowire nucleation\nis enhanced by sputtering the silicon substrate with energetic particles. We\nargue that particle bombardment introduces lattice defects on the silicon\nsurface that serve as preferential nucleation sites. The formation of these\nnucleation sites can be controlled by the sputtering parameters, allowing the\ncontrol of nanowire density in a wide range. Nanowire nucleation is accompanied\nby unwanted parasitic islands, but by careful choice of annealing and growth\ntemperature allows to strongly reduce the relative density of these islands and\nto realize samples with high nanowire yield."
    },
    {
        "anchor": "Proposal for Manipulation of Majorana Fermions in Nano-Patterned\n  Semiconductor-Superconductor Heterostructure: We investigate a heterostructure system with a spin-orbit coupled\nsemiconductor sandwiched by an s-wave superconductor and a ferromagnetic\ninsulator, which supports Majorana fermions (MFs) at the superconducting vortex\ncores. We propose a scheme of transporting and braiding the MFs, which only\nrequires application of point-like gate voltages in a system with nano-meter\npatterns. By solving the time-dependent Bogoliubov-de Gennes equation\nnumerically, we monitor the time evolutions of MF wave-functions and show that\nthe braiding of MFs with non-Abelian statistics can be achieved by adiabatic\nswitching within several nano seconds.",
        "positive": "Tunable crossed Andreev reflection in a heterostructure consisting of\n  ferromagnets, normal metal and superconductors: Crossed Andreev reflection (CAR) is a nonlocal transport phenomenon in a\nsystem of two normal metal (NM) leads connected to a superconductor (SC) that\nconverts the electron like excitations in one metallic lead into hole like\nexcitations in the other metallic lead. The scattering phenomena viz. electron\ntunneling (ET), electron reflection (ER) and Andreev reflection (AR) compete\nwith CAR and reduce the probability of CAR generically. One of the\nexperimentally realized proposals to observe CAR is to employ two ferromagnetic\n(FM) leads in antiparallel configuration connected to the SC by suppressing ET\nand AR. But CAR probability cannot be tuned in this setup. We propose a setup\nconsisting of a gate tunable NM region connected to two superconducting regions\non either side which are connected to FM leads further away in antiparallel\nconfiguration, in which probabilities of CAR and ER can be changed from $0$ to\n$1$ by a changing the gate voltage applied to the NM region. The gate voltage\napplied to the NM region dictates the chemical potential of the NM region and\ngives a handle on the Fabry-P\\'erot interference of the electron and hole modes\nin the NM region. We calculate differential transconductance for the proposed\nsetup which can be tuned across the range $0$ to $-e^2/h$."
    },
    {
        "anchor": "Chiral tunneling of topological states: towards the efficient generation\n  of spin current using spin-momentum locking: We show that the interplay between chiral tunneling and spin-momentum locking\nof helical surface states leads to spin amplification and filtering in a 3D\nTopological Insulator (TI). Chiral tunneling across a TI pn junction allows\nnormally incident electrons to transmit, while the rest are reflected with\ntheir spins flipped due to spin-momentum locking. The net result is that the\nspin current is enhanced while the dissipative charge current is simultaneously\nsuppressed, leading to an extremely large, gate tunable spin to charge current\nratio (~20) at the reflected end. At the transmitted end, the ratio stays close\nto one and the electrons are completely spin polarized.",
        "positive": "Orbital magnetization of Floquet topological systems: A general expression for the orbital magnetization of a Floquet system is\nderived. The expression holds for a clean system, and is valid for any driving\nprotocol, and arbitrary occupation of the bands. The orbital magnetization is\nshown to be large not only for Chern insulators, but also for anomalous phases\nwhere the Chern number does not fully account for the topology. In addition,\nthe orbital magnetization is shown to take significant values both for a\nthermal equilibrium occupation of the Floquet bands, and for occupations\ndetermined by a quantum quench from an initial state with zero orbital\nmagnetization. For the latter case, the orbital magnetization is shown to be\nhighly sensitive to van Hove singularities of the Floquet bands."
    },
    {
        "anchor": "The effect of uniaxial pressure on the magnetic anisotropy of the\n  Mn_{12}-Ac single-molecule magnet: We study the effect of uniaxial pressure on the magnetic hysteresis loops of\nthe single-molecule magnet Mn_{12}-Ac. We find that the application of pressure\nalong the easy axis increases the fields at which quantum tunneling of\nmagnetization occurs. The observations are attributed to an increase in the\nmolecule's magnetic anisotropy constant D of 0.142(1)%/kbar. The increase in D\nproduces a small, but measurable increase in the effective energy barrier for\nmagnetization reversal. Density-functional theory calculations also predict an\nincrease in the barrier with applied pressure.",
        "positive": "RKKY interaction in a disordered two-dimensional electron gas with\n  Rashba and Dresselhaus spin-orbit couplings: We study theoretically the statistical properties of the\nRuderman-Kittel-Kasuya-Yosida (RKKY) interaction between localized magnetic\nmoments in a disordered two-dimensional electron gas with both Rashba and\nDresselhaus spin-orbit couplings. Averaging over disorder, the static spin\nsusceptibility tensor is evaluated diagrammatically in the mesoscopic\n(phase-coherent) regime. The disorder-averaged susceptibility leads to a\ntwisted exchange interaction suppressed exponentially with distance, whereas\nthe second-order correlations, which determine the fluctuations (variance) of\nthe RKKY energy, decay with the same power-law as in the clean case. We obtain\nanalytic expressions in the limits of large/small spin orbit interactions and\nfor equal Rashba and Dresselhaus couplings. Beside these limiting cases, we\nstudy numerically the variance of the RKKY interaction in the presence of pure\nRashba spin-orbit coupling. Our results are relevant for magnetic impurities or\nnuclear moments embedded in III-V two-dimensional heterostructures or in\ncontact with surface states of metals and metal alloys, which can display a\nsizable Rashba spin-orbit coupling."
    },
    {
        "anchor": "Electronic structure of multilayer graphene: We study the electronic structure of multilayer graphene using a\n$\\pi$-orbital continuum model with nearest-neighbor intralayer and interlayer\ntunneling. Using degenerate state perturbation theory, we show that the\nlow-energy electronic structure of arbitrarily stacked graphene multilayers\nconsists of chiral pseudospin doublets with a conserved chirality sum.",
        "positive": "The spin Hall effect: In metallic systems with spin-orbit coupling a longitudinal charge current\nmay generate a transverse pure spin current; vice-versa an injected pure spin\ncurrent may result in a transverse charge current. Such direct and inverse spin\nHall effects share the same microscopic origin: intrinsic band/device structure\nproperties, external factors such as impurities, or a combination of both. They\nallow all-electrical manipulation of the electronic spin degrees of\nfreedom,i.e. without magnetic elements, and their transverse nature makes them\npotentially dissipationless. It is customary to talk of spin Hall effects in\nplural form, referring to a group of related phenomena typical of spin-orbit\ncoupled systems of lowered symmetry."
    },
    {
        "anchor": "Ultrahigh magnetic field spectroscopy reveals the band structure of the\n  3D topological insulator Bi$_2$Se$_3$: We have investigated the band structure at the $\\Gamma$ point of the\nthree-dimensional (3D) topological insulator Bi$_2$Se$_3$ using\nmagneto-spectroscopy over a wide range of energies ($0.55-2.2$\\,eV) and in\nultrahigh magnetic fields up to 150\\,T. At such high energies ($E>0.6$\\,eV) the\nparabolic approximation for the massive Dirac fermions breaks down and the\nLandau level dispersion becomes nonlinear. At even higher energies around 0.99\nand 1.6 eV, new additional strong absorptions are observed with a temperature\nand magnetic-field dependence which suggest that they originate from higher\nband gaps. Spin orbit splittings for the further lying conduction and valence\nbands are found to be 0.196 and 0.264 eV.",
        "positive": "Comment on 'Field ion microscopy characterized tips in noncontact atomic\n  force microscopy: Quantification of long-range force interactions': A recent article by Falter et al. (Phys. Rev. B 87, 115412 (2013)) presents\nexperimental results using field ion microscopy characterized tips in\nnoncontact atomic force microscopy in order to characterize electrostatic and\nvan der Waals long range forces. In the article, the tip radius was\nsubstantially underestimated at ~4.7 nm rather than ~8.1 nm due to subtleties\nin the application of the ring counting method. We point out where common\nerrors in ring counting arise in order to benefit future experimental work in\nwhich the determination of tip radius by FIM is important."
    },
    {
        "anchor": "Fine structure of exciton excited levels in a quantum dot with a\n  magnetic ion: The fine structure of excited excitonic states in a quantum dot with an\nembedded magnetic ion is studied theoretically and experimentally. The\ndeveloped theory takes into account the Coulomb interaction between charged\ncarriers, the anisotropic long-range electron-hole exchange interaction in the\nzero-dimensional exciton, and the exchange interaction of the electron and the\nhole with the $d$-electrons of a Mn ion inserted inside the dot. Depending on\nthe relation between the quantum dot anisotropy and the exciton-Mn coupling the\nphotoluminescence excitation spectrum has a qualitatively different behavior.\nIt provides a deep insight into the spin structure of the excited excitonic\nstates.",
        "positive": "Atomic relaxation and electronic structure in twisted bilayer MoS2 with\n  rotation angle of 5.09 degrees: It is now well established theoretically and experimentally that a moir\\'e\npattern, due to a rotation of two atomic layers with respect to each other,\ncreates low-energy flat bands. First discovered in twisted bilayer graphene,\nthese new electronic states are at the origin of strong electronic correlations\nand even of unconventional superconductivity. Twisted bilayers (tb) of\ntransition metal dichalcogenides (TMDs) also exhibit flat bands around their\nsemiconductor gap at small rotation angles. In this paper, we present a DFT\nstudy to analyze the effect of the atomic relaxation on the low-energy bands of\ntb-MoS2 with a rotation angle of 5.09 degrees. We show that in-plane atomic\nrelaxation is not essential here, while out-of-plane relaxation dominates the\nelectronic structure. We propose a simple and efficient atomic model to predict\nthis relaxation."
    },
    {
        "anchor": "Macroscopic transport of a current-induced spin polarization: Experimental studies of spin transport in a two-dimensional electron gas\nhosted by a triple GaAs/AlGaAs quantum well are reported. Using time-resolved\nKerr rotation, we observed the precession of the spin polarization about a\ncurrent-controlled spin-orbit magnetic field. Spatially-resolved imaging showed\na large variation of the electron g-factor and the drift transport of coherent\nelectron spins over distances exceeding half-millimetre in a direction\ntransverse to the electric field.",
        "positive": "Thermodynamics and kinetics of H adsorption and intercalation for\n  graphene on 6H-SiC(0001) from first-principles calculations: Previous experimental observations for H intercalation under graphene on SiC\nsurfaces motivate clarification of configuration stabilities and kinetic\nprocesses related to intercalation. From first-principles\ndensity-functional-theory (DFT) calculations, we analyze H adsorption and\nintercalation for graphene on a 6H-SiC(0001) surface, where the system includes\ntwo single-atom-thick graphene layers: the top-layer graphene (TLG) and the\nunderling buffer-layer graphene (BLG) above the terminal Si layer. Our chemical\npotential analysis shows that, in the low-H coverage regime (described by a\nsingle H atom within a sufficiently large supercell), intercalation into the\ngallery between TLG and BLG, or into the gallery underneath BLG, is more\nfavorable thermodynamically than adsorption on top of TLG. However,\nintercalation into the gallery between TLG and BLG is most favorable. We obtain\nenergy barriers of about 1.3 eV and 2.3 eV for a H atom diffusing on and under\nTLG, respectively. From an additional analysis of the energy landscape in the\nvicinity of a step on the TLG, we assess how readily one guest H atom on the\nTLG terrace can directly penetrate the TLG into the gallery between TLG and BLG\nversus crossing a TLG step to access the gallery. We also perform DFT\ncalculations for higher H coverages revealing a shift in favorability to\nintercalation of H underneath BLG, as well as characterizing the variation with\nH coverage in interlayer spacings."
    },
    {
        "anchor": "An ultrasensitive spintronic strain sensor: We propose a spintronic strain sensor capable of sensing strain with a\nsensitivity of 1E-13/sqrt{Hz} at room temperature with an active sensing area\nof 1 cmE2 and power dissipation of 1 watt. This device measures strain by\nmonitoring the change in the spin-polarized current in a parallel array of free\nstanding nanowire spin valves when the array is subjected to compressive or\ntensile stress along the wires' length. The change in the current is linearly\nproportional to the strain, which makes the sensor relatively distortion-free.\nSuch a sensor can be fabricated using a variety of techniques involving\nnanolithography, self assembly and epitaxial growth.",
        "positive": "Electronic Structure of Mononuclear Cu-based Molecule from\n  Density-Functional Theory with Self-Interaction Correction: We investigate the electronic structure of a planar mononuclear Cu-based\nmolecule [Cu(C$_6$H$_4$S$_2$)$_2$]$^z$ in two oxidation states ($z$$=$$-2$,\n$-$1) using density-functional theory (DFT) with Fermi-L\\\"owdin orbital (FLO)\nself-interaction correction (SIC). The dianionic Cu-based molecule was proposed\nto be a promising qubit candidate. Self-interaction error within approximate\nDFT functionals renders severe delocalization of electron and spin densities\narising from 3$d$ orbitals. The FLO-SIC method relies on optimization of\nFermi-L\\\"owdin orbital descriptors (FODs) with which localized occupied\norbitals are constructed to create the SIC potentials. Starting with many\ninitial sets of FODs, we employ a frozen-density loop algorithm within the\nFLO-SIC method to study the Cu-based molecule. We find that the electronic\nstructure of the molecule remains unchanged despite somewhat different final\nFOD configurations. In the dianionic state (spin $S=1/2$), FLO-SIC spin density\noriginates from the Cu $d$ and S $p$ orbitals with an approximate ratio of 2:1,\nin quantitative agreement with multireference calculations, while in the case\nof SIC-free DFT, the orbital ratio is reversed. Overall, FLO-SIC lowers the\nenergies of the occupied orbitals and in particular the 3$d$ orbitals\nunhybridized with the ligands significantly, which substantially increases the\nenergy gap between the highest occupied molecular orbital (HOMO) and the lowest\nunoccupied molecular orbital (LUMO) compared to SIC-free DFT results. The\nFLO-SIC HOMO-LUMO gap of the dianionic state is larger than that of the\nmonoionic state, which is consistent with experiment. Our results suggest a\npositive outlook of the FLO-SIC method in the description of magnetic exchange\ncoupling within 3$d$-element based systems."
    },
    {
        "anchor": "Aharonov-Bohm conductance oscillations and current equilibration in\n  local n - p junctions in graphene: We consider a small p-type island defined within n-type graphene nanoribbon\ninduced by potential of a floating electrode. In the quantum Hall conditions\nthe island supports persistent currents localized at the $n-p$ junction. When\ncoupled to the graphene edge the island acts as an Aharonov-Bohm\ninterferometer. We evaluate the electrostatic potential induced by the floating\ngate within the ribbon near the charge neutrality point and consider\nequilibration of the currents at both sides of the junction. The incoherent\nequilibration is introduced by the virtual probes technique. We describe the\nevolution of the coherent Aharonov-Bohm conductance oscillations to the quantum\nHall fractional plateaus due to the current equilibration.",
        "positive": "Probing (topological) Floquet states through DC transport: We consider the differential conductance of a periodically driven system\nconnected to infinite electrodes. We focus on the situation where the\ndissipation occurs predominantly in these electrodes. Using analytical\narguments and a detailed numerical study we relate the differential\nconductances of such a system in two and three terminal geometries to the\nspectrum of quasi-energies of the Floquet operator. Moreover these differential\nconductances are found to provide an accurate probe of the existence of gaps in\nthis quasi-energy spectrum, being quantized when topological edge states occur\nwithin these gaps. Our analysis opens the perspective to describe the\nintermediate time dynamics of driven mesoscopic conductors as topological\nFloquet filters."
    },
    {
        "anchor": "Fano-shaped impurity spectral density, electric-field-induced in-gap\n  state and local magnetic moment of an adatom on trilayer graphene: Recently, the existence of local magnetic moment in a hydrogen adatom on\ngraphene has been confirmed experimentally [Gonz\\'{a}lez-Herrero et al.,\nScience, 2016, 352, 437]. Inspired by this breakthrough, we theoretically\ninvestigate the top-site adatom on trilayer graphene (TLG) by solving the\nAnderson impurity model via self-consistent mean field method. The influence of\nthe stacking order, the adsorption site and external electric field are\ncarefully considered. We find that, due to its unique electronic structure, the\nsituation of the TLG is drastically different from that of the monolayer\ngraphene. Firstly, the adatom on rhombohedral stacked TLG (r-TLG) can have a\nFano-shaped impurity spectral density, instead of the normal Lorentzian-like\none, when the impurity level is around the Fermi level. Secondly, the impurity\nlevel of the adatom on r-TLG can be tuned into an in-gap state by an external\nelectric field, which strongly depends on the direction of the applied electric\nfield and can significantly affect the local magnetic moment formation.\nFinally, we systematically calculate the impurity magnetic phase diagrams,\nconsidering various stacking orders, adsorption sites, doping and electric\nfield. We show that, because of the in-gap state, the impurity magnetic phase\nof r-TLG will obviously depend on the direction of the applied electric field\nas well. All our theoretical results can be readily tested in experiment, and\nmay give a comprehensive understanding about the local magnetic moment of\nadatom on TLG.",
        "positive": "Machine learning topological phases in real space: We develop a supervised machine learning algorithm that is able to learn\ntopological phases of finite condensed matter systems from bulk data in real\nlattice space. The algorithm employs diagonalization in real space together\nwith any supervised learning algorithm to learn topological phases through an\neigenvector ensembling procedure. We combine our algorithm with decision trees\nand random forests to successfully recover topological phase diagrams of\nSu-Schrieffer-Heeger (SSH) models from bulk lattice data in real space and show\nhow the Shannon information entropy of ensembles of lattice eigenvectors can be\nused to retrieve a signal detailing how topological information is distributed\nin the bulk. We further use insights obtained from these information entropy\nsignatures to engineer global topological features from real space lattice data\nthat still carry most of the topological information in the lattice, while\ngreatly diminishing the size of feature space, thus effectively amounting to a\ntopological lattice compression. Finally, we explore the theoretical\npossibility of interpreting the information entropy topological signatures in\nterms of emergent information entropy wave functions, which lead us to\nHeisenberg and Hirschman uncertainty relations for topological phase\ntransitions. The discovery of Shannon information entropy signals associated\nwith topological phase transitions from the analysis of data from several\nthousand SSH systems illustrates how model explainability in machine learning\ncan advance the research of exotic quantum materials with properties that may\npower future technological applications such as qubit engineering for quantum\ncomputing."
    },
    {
        "anchor": "Quasi free-standing silicene in a superlattice with hexagonal boron\n  nitride: We study a superlattice of silicene and hexagonal boron nitride by first\nprinciples calculations and demonstrate that the interaction between the layers\nof the superlattice is very small. As a consequence, quasi free-standing\nsilicene is realized in this superlattice. In particular, the Dirac cone of\nsilicene is preserved, which has not been possible in any other system so far.\nDue to the wide band gap of hexagonal boron nitride, the superlattice realizes\nthe characteristic physical phenomena of free-standing silicene. In particular,\nwe address by model calculations the combined effect of the intrinsic\nspin-orbit coupling and an external electric field, which induces a transition\nfrom a metal to a topological insulator and further to a band insulator.",
        "positive": "Quantization of Hall Conductance in Double Exchange Systems: Topology\n  and Lattice Gauge Field: We study quantization conditions of the Hall conductivity for a two\ndimensional system described by a double exchange Hamiltonian with and without\nan external magnetic field. This is obtained by an extension of the topological\narguments familiar from the theory of the integer quantum Hall effect. The\nquantization conditions are related to spontaneous breaking of spin O(3),\ntime-reversal, and spin chiral symmetries. Extension to systems with higher\ndimensions is briefly discussed."
    },
    {
        "anchor": "Frequency stabilization of the zero-phonon line of a quantum dot via\n  phonon-assisted active feedback: We report on the feedback stabilization of the zero-phonon emission frequency\nof a single InAs quantum dot. The spectral separation of the phonon-assisted\ncomponent of the resonance fluorescence provides a probe of the detuning\nbetween the zero-phonon transition and the resonant driving laser. Using this\nprobe in combination with active feedback, we stabilize the zero-phonon\ntransition frequency against environmental fluctuations. This protocol reduces\nthe zero-phonon fluorescence intensity noise by a factor of 22 by correcting\nfor environmental noise with a bandwidth of 191 Hz, limited by the experimental\ncollection efficiency. The associated sub-Hz fluctuations in the zero-phonon\ncentral frequency are reduced by a factor of 7. This technique provides a means\nof stabilizing the quantum dot emission frequency without requiring access to\nthe zero-phonon emission.",
        "positive": "Tuning the Threshold Voltage of MoS2 Field-Effect Transistors via\n  Surface Treatment: Controlling the threshold voltage (Vth) of a field-effect transistor is\nimportant for realizing robust logic circuits. Here, we report a facile\napproach to achieve bidirectional Vth tuning of molybdenum disulfide (MoS2)\nfield-effect transistors. By increasing and decreasing the amount of sulfur\nvacancies in the MoS2 surface, the Vth of MoS2 transistors can be left- and\nright-shifted, respectively. Transistors fabricated on perfect MoS2 flakes are\nfound to exhibit two-fold enhancement in mobility and a very positive Vth. More\nimportantly, our elegant hydrogen treatment is able to tune the large Vth to a\nsmall value without any performance degradation simply by reducing the atomic\nratio of S:Mo slightly; in other words, creating a certain amount of sulfur\nvacancies in the MoS2 surface, which generate defect states in the band gap of\nMoS2 that mediate conduction of a MoS2 transistor in the subthreshold regime.\nFirst-principles calculations further indicate that the edge and width of\ndefect band can be tuned according to the vacancy density. This work not only\ndemonstrates for the first time the ease in tuning the Vth of MoS2 transistors,\nbut also offers a process technology solution that is critical for further\ndevelopment of MoS2 as a mainstream electronic material."
    },
    {
        "anchor": "Dynamical diffusion and renormalization group equation for the Fermi\n  velocity in doped graphene: The aim of this work is to study the electron transport in graphene with\nimpurities by introducing a generalization of linear response theory for linear\ndispersion relations and spinor wave functions. Current response and density\nresponse functions are derived and computed in the Boltzmann limit, showing\nthat in the former case, a minimum conductivity appears in the no-disorder\nlimit. In turn, from the generalization of both functions, an exact relation\ncan be obtained that relates both. Combining this result with the relation\ngiven by the continuity equation, it is possible to obtain general functional\nbehavior of the diffusion pole. Finally, a dynamical diffusion is computed in\nthe quasistatic limit using the definition of relaxation function. A lower\ncutoff must be introduced to regularize infrared divergences, which allow us to\nobtain a full renormalization group equation for the Fermi velocity, which is\nsolved up to order O(h^2).",
        "positive": "Supermoir\u00e9 low-energy effective theory of twisted trilayer graphene: Stacking three monolayers of graphene with a twist generally produces two\nmoir\\'e patterns. A moir\\'e of moir\\'e structure then emerges at larger\ndistance where the three layers periodically realign. We devise here an\neffective low-energy theory to describe the spectrum at distances larger than\nthe moir\\'e lengthscale. In each valley of the underlying graphene, the theory\ncomprises one Dirac cone at the ${\\bf \\Gamma}_M$ point of the moir\\'e Brillouin\nzone and two weakly gapped points at ${\\bf K}_M$ and ${\\bf K}'_M$. The\nvelocities and small gaps exhibit a spatial dependence in the\nmoir\\'e-of-moir\\'e unit cell, entailing a non-abelian connection potential\nwhich ensures gauge invariance. The resulting model is numerically solved and a\nfully connected spectrum is obtained, which is protected by the combination of\ntime-reversal and twofold-rotation symmetries."
    },
    {
        "anchor": "Edge magnetism impact on electrical conductance and thermoelectric\n  properties of graphenelike nanoribbons: Edge states in narrow quasi two-dimensional nanostructures determine, to a\nlarge extent, their electric, thermoelectric and magnetic properties.\nNon-magnetic edge states may quite often lead to topological insulator type\nbehavior. However another scenario develops when the zigzag edges are magnetic\nand the time reversal symmetry is broken. In this work we report on the\nelectronic band structure modifications, electrical conductance and\nthermoelectric properties of narrow zigzag nanoribbons with spontaneously\nmagnetized edges. Theoretical studies based on the Kane-Mele- Hubbard\ntight-binding model show that for silicene, germanene and stanene both the\nSeebeck coefficient and the thermoelectric power factor are strongly enhanced\nfor energies close to the charge neutrality point. Perpendicular gate voltage\nlifts the spin degeneracy of energy bands in the ground state with antiparallel\nmagnetized zigzag edges and makes the electrical conductance significantly\nspin-polarized. Simultaneously the gate voltage worsens the thermoelectric\nperformance. Estimated room-temperature figures of merit for the aforementioned\nnanoribbons can exceed a value of 3 if phonon thermal conductances are\nadequately reduced.",
        "positive": "Control of spin current by a magnetic YIG substrate in NiFe/Al nonlocal\n  spin valves: We study the effect of a magnetic insulator (Yttrium Iron Garnet - YIG)\nsubstrate on the spin transport properties of Ni$_{80}$Fe$_{20}$/Al nonlocal\nspin valve (NLSV) devices. The NLSV signal on the YIG substrate is about 2 to 3\ntimes lower than that on a non magnetic SiO$_2$ substrate, indicating that a\nsignificant fraction of the spin-current is absorbed at the Al/YIG interface.\nBy measuring the NLSV signal for varying injector-to-detector distance and\nusing a three dimensional spin-transport model that takes spin current\nabsorption at the Al/YIG interface into account we obtain an effective\nspin-mixing conductance $G_{\\uparrow\\downarrow}\\simeq 5 - 8\\times\n10^{13}~\\Omega^{-1}$m$^{-2}$. We also observe a small but clear modulation of\nthe NLSV signal when rotating the YIG magnetization direction with respect to\nthe fixed spin polarization of the spin accumulation in the Al. Spin relaxation\ndue to thermal magnons or roughness of the YIG surface may be responsible for\nthe observed small modulation of the NLSV signal."
    },
    {
        "anchor": "Influence of nanoparticle surface and shape on the dipole magnetic\n  absorption of ultrashort laser pulses: The theory on the magnetic field energy absorption by metal nanoparticles of\na nonspherical shape irradiated with ultrashort laser pulses of different\nduration is developed. The effect of both the particle surface and the particle\nshape on the absorbed energy is studied. For the particles having an oblate or\nprolate spheroidal shape, the dependence of this energy on the orientation of\nthe magnetic field upon a particle, the degree of its deviation from a\nspherical shape, a pulse duration, and the carrier frequency of the laser ray\nare found. A significant increase in the absorption is established when an\nelectron mean free path coincides with the size of the particle. The Drude and\nkinetic approaches are used and the results are compared with each other.",
        "positive": "Electron cooling in graphene enhanced by plasmon-hydron resonance: Evidence is accumulating for the crucial role of a solid's free electrons in\nthe dynamics of solid-liquid interfaces. Liquids induce electronic polarization\nand drive electric currents as they flow; electronic excitations, in turn,\nparticipate in hydrodynamic friction. Yet, the underlying solid-liquid\ninteractions have been lacking a direct experimental probe. Here, we study the\nenergy transfer across liquid-graphene interfaces using ultrafast spectroscopy.\nThe graphene electrons are heated up quasi-instantaneously by a visible\nexcitation pulse, and the time evolution of the electronic temperature is then\nmonitored with a terahertz pulse. We observe that water accelerates the cooling\nof the graphene electrons, whereas other polar liquids leave the cooling\ndynamics largely unaffected. A quantum theory of solid-liquid heat transfer\naccounts for the water-specific cooling enhancement through a resonance between\nthe graphene surface plasmon mode and the so-called hydrons -- water charge\nfluctuations --, particularly the water libration modes, that allows for\nefficient energy transfer. Our results provide direct experimental evidence of\na solid-liquid interaction mediated by collective modes and support the\ntheoretically proposed mechanism for quantum friction. They further reveal a\nparticularly large thermal boundary conductance for the water-graphene\ninterface and suggest strategies for enhancing the thermal conductivity in\ngraphene-based nanostructures."
    },
    {
        "anchor": "Characterization of the size and position of electron-hole puddles at a\n  graphene p-n junction: The effect of an electron-hole puddle on the electrical transport when\ngoverned by snake states in a bipolar graphene structure is investigated. Using\nnumerical simulations we show that information on the size and position of the\nelectron-hole puddle can be obtained using the dependence of the conductance on\nmagnetic field and electron density of the gated region. The presence of the\nscatterer disrupts snake state transport which alters the conduction pattern.\nWe obtain a simple analytical formula that connects the position of the\nelectron-hole puddle with features observed in the conductance. Size of the\nelectron-hole puddle is estimated from the magnetic field and gate potential\nthat maximizes the effect of the puddle on the electrical transport.",
        "positive": "Observation of half-integer quantum Hall effect in single-layer graphene\n  using pulse magnet: We report magnetotransport measurements on a single-layer graphene in pulsed\nmagnetic fields up to $B$ = 53 T. With either electron- or hole-type charge\ncarriers, the Hall resistance $R_{H}$ is quantized into $R_{H}$ = $(h/e^2)\\nu\n^{-1}$ with $\\nu$ = $\\pm$2, $\\pm$6, and $\\pm$10, which demonstrates the\nobservation of half-integer quantum Hall effect (QHE). At $B$ = 50 T, the\nhalf-integer QHE is even observed at room temperature in spite of a\nconventional carrier mobility $\\mu$ = 4000 cm$^2$/Vs."
    },
    {
        "anchor": "Spin noise and Bell inequalities in a realistic superconductor-quantum\n  dot entangler: Charge and spin current correlations are analyzed in a source of\nspin-entangled electrons built from a superconductor and two quantum dots in\nparallel. In addition to the ideal (crossed Andreev) channel, parasitic\nchannels (direct Andreev and cotunneling) and spin flip processes are fully\ndescribed in a density matrix framework. The way they reduce both the\nefficiency and the fidelity of the entangler is quantitatively described by\nanalyzing the zero-frequency noise correlations of charge current as well as\nspin current in the two output branches. Spin current noise is characterized by\na spin Fano factor, equal to 0 (total current noise) and -1 (crossed\ncorrelations) for an ideal entangler. The violation of the Bell inequalities,\nas a test of non-locality (entanglement) of split pairs, is formulated in terms\nof the correlations of electron charge and spin numbers counted in a specific\ntime window $\\tau$. The efficiency of the test is analyzed, comparing $\\tau$ to\nthe various time scales in the entangler operation.",
        "positive": "Surface state atoms and their contribution to the surface tension of\n  quantum liquids: We investigate the new type of excitations on the surface of liquid helium.\nThese excitations, called surfons, appear because helium atoms have discrete\nenergy level at the liquid surface, being attracted to the surface by the van\nder Waals force and repulsed at a hard-core interatomic distance. The\nconcentration of the surfons increases with temperature. The surfons propagate\nalong the surface and form a two-dimensional gas. Basing on the simple model of\nthe surfon microscopic structure, we estimate the surfon activation energy and\neffective mass for both helium isotopes. We also calculate the contribution of\nthe surfons to the temperature dependence of the surface tension. This\ncontribution explains the great and long-standing discrepancy between theory\nand experiment on this temperature dependence in both helium isotopes. The\nachieved agreement between our theory and experiment is extremely high. The\ncomparison with experiment allows to extract the surfon activation energy and\neffective mass. The values of these surfon microscopic parameters are in a\nreasonable agreement with the calculated from the proposed simple model of\nsurfon structure."
    },
    {
        "anchor": "STM/S study of electronic inhomogeneity evolution with gate voltage in\n  graphene: role of screening and charge-state of interface defects: Evolution of electronic inhomogeneities with back-gate voltage in graphene on\nSiO$_2$ was studied using room temperature scanning tunneling microscopy and\nspectroscopy. The reversal of local contrast in some places in the STS maps and\nsharp changes in cross-correlations between topographic and conductance maps,\nwhen graphene Fermi energy approaches its Dirac point, are attributed to change\nin charge-state of interface defects. The spatial correlations in the\nconductance maps, described by two different length scales and their growth\nduring approach to Dirac point, show a qualitative agreement with the\npredictions of the screening theory of graphene. Thus a sharp change in the two\nlength-scales close to the Dirac point, seen in our experiments, is interpreted\nin terms of the change in charge state of some of the interface defects. A\nsystematic understanding and control of the charge state of defects will help\nin memory applications of graphene.",
        "positive": "Full Classification of Transport on an Equilibrated 5/2 Edge via Shot\n  Noise: The nature of the bulk topological order of the 5/2 non-Abelian fractional\nquantum Hall state and the steady-state of its edge are long-studied questions.\nThe most promising non-Abelian model bulk states are the Pfaffian (Pf),\nanti-Pffafian (APf), and particle-hole symmetric Pfaffian (PHPf). Here, we\npropose to employ a set of dc current-current correlations \\emph{(electrical\nshot noise)} in order to distinguish among the Pf, APf, and PHPf candidate\nstates, as well as to determine their edge thermal equilibration regimes: full\nvs.\\ partial. Using other tools, measurements of GaAs platforms have already\nindicated consistency with the PHPf state. Our protocol, realizable with\navailable experimental tools, is based on fully electrical measurements."
    },
    {
        "anchor": "Electrical manipulation of spin states in a single electrostatically\n  gated transition-metal complex: We demonstrate an electrically controlled high-spin (S=5/2) to low-spin\n(S=1/2) transition in a three-terminal device incorporating a single Mn2+ ion\ncoordinated by two terpyridine ligands. By adjusting the gate-voltage we reduce\nthe terpyridine moiety and thereby strengthen the ligand-field on the Mn-atom.\nAdding a single electron thus stabilizes the low-spin configuration and the\ncorresponding sequential tunnelling current is suppressed by spin-blockade.\n  From low-temperature inelastic cotunneling spectroscopy, we infer the\nmagnetic excitation spectrum of the molecule and uncover also a strongly\ngate-dependent singlet-triplet splitting on the low-spin side. The measured\nbias-spectroscopy is shown to be consistent with an exact diagonalization of\nthe Mn-complex, and an interpretation of the data is given in terms of a\nsimplified effective model.",
        "positive": "Transmission spectra and valley processing of graphene and carbon\n  nanotube superlattices with inter-valley coupling: We numerically investigate the electronic transport properties of graphene\nnanoribbons and carbon nanotubes with inter-valley coupling, e.g., in \\sqrt{3}N\n\\times \\sqrt{3}N and 3N \\times 3N superlattices. By taking the \\sqrt{3} \\times\n\\sqrt{3} graphene superlattice as an example, we show that tailoring the bulk\ngraphene superlattice results in rich structural configurations of nanoribbons\nand nanotubes. After studying the electronic characteristics of the\ncorresponding armchair and zigzag nanoribbon geometries, we find that the\nlinear bands of carbon nanotubes can lead to the Klein tunnelling-like\nphenomenon, i.e., electrons propagate along tubes without backscattering even\nin the presence of a barrier. Due to the coupling between K and K' valleys of\npristine graphene by \\sqrt{3} \\times \\sqrt{3} supercells,we propose a\nvalley-field-effect transistor based on the armchair carbon nanotube, where the\nvalley polarization of the current can be tuned by applying a gate voltage or\nvarying the length of the armchair carbon nanotubes."
    },
    {
        "anchor": "Currents in a many-particle parabolic quantum dot under a strong\n  magnetic field: Currents in a few-electron parabolic quantum dot placed into a perpendicular\nmagnetic field are considered. We show that traditional ways of investigating\nthe Wigner crystallization by studying the charge density correlation function\ncan be supplemented by the examination of the density-current correlator.\nHowever, care must be exercised when constructing the correct projection of the\nmulti-dimensional wave function space. The interplay between the magnetic field\nand Euler-liquid-like behavior of the electron liquid gives rise to persistent\nand local currents in quantum dots. We demonstrate these phenomena by collating\na quasi-classical theory valid in high magnetic fields and an exact numerical\nsolution of the many-body problem.",
        "positive": "High-sensitivity diamond magnetometer with nanoscale resolution: We present a novel approach to the detection of weak magnetic fields that\ntakes advantage of recently developed techniques for the coherent control of\nsolid-state electron spin quantum bits. Specifically, we investigate a magnetic\nsensor based on Nitrogen-Vacancy centers in room-temperature diamond. We\ndiscuss two important applications of this technique: a nanoscale magnetometer\nthat could potentially detect precession of single nuclear spins and an optical\nmagnetic field imager combining spatial resolution ranging from micrometers to\nmillimeters with a sensitivity approaching few femtotesla/Hz$^{1/2}$."
    },
    {
        "anchor": "Low carrier concentration crystals of the topological insulator\n  Bi$_{2-x}$Sb$_{x}$Te$_{3-y}$Se$_{y}$: a magnetotransport study: In 3D topological insulators achieving a genuine bulk-insulating state is an\nimportant research topic. Recently, the material system\n(Bi,Sb)$_{2}$(Te,Se)$_{3}$ (BSTS) has been proposed as a topological insulator\nwith high resistivity and a low carrier concentration (Ren \\textit{et al.}\n\\cite{Ren2011}). Here we present a study to further refine the bulk-insulating\nproperties of BSTS. We have synthesized Bi$_{2-x}$Sb${_x}$Te$_{3-y}$Se$_{y}$\nsingle crystals with compositions around $x = 0.5$ and $y = 1.3$. Resistance\nand Hall effect measurements show high resistivity and record low bulk carrier\ndensity for the composition Bi$_{1.46}$Sb$_{0.54}$Te$_{1.7}$Se$_{1.3}$. The\nanalysis of the resistance measured for crystals with different thicknesses\nwithin a parallel resistor model shows that the surface contribution to the\nelectrical transport amounts to 97% when the sample thickness is reduced to $1\n\\mu$m. The magnetoconductance of exfoliated BSTS nanoflakes shows 2D weak\nantilocalization with $\\alpha \\simeq -1$ as expected for transport dominated by\ntopological surface states.",
        "positive": "Quantitative relationship between polarization differences and the\n  zone-averaged shift photocurrent: A relationship is derived between differences in electric polarization\nbetween bands and the \"shift vector\" that controls part of a material's bulk\nphotocurrent, then demonstrated in several models. Electric polarization has a\nquantized gauge ambiguity and is normally observed at surfaces via the surface\ncharge density, while shift current is a bulk property and is described by\nshift vector gauge invariant at each point in momentum space. They are\nconnected because the same optical transitions that are described in shift\ncurrents pick out a relative gauge between valence and conduction bands. We\nalso discuss subtleties arising when there are points at the Brillouin zone\nwhere optical transitions are absent. We conclude that two-dimensional\nmaterials with significant interband polarization differences should have high\nbulk photocurrent, meaning that the modern theory of polarization can be used\nas a straightforward way to search for bulk photovoltaic material candidates."
    },
    {
        "anchor": "Spin wave excitations in a nanowire spin-torque oscillator with\n  perpendicular magnetic anisotropy: Spin torque oscillators (STOs) are emerging microwave devices that can\npotentially be used in spin-logic devices and the next-generation high-speed\ncomputing architecture. Thanks to their non-linear nature, STOs are easily\ntunable by the magnetic field and the dc current. Spin Hall nano-oscillators\n(SHNOs) are promising types of STOs and most of the current studies focus on\nlocalized modes that can be easily excited. Here, we study using micromagnetic\nsimulations, the nature of the spin-torque-induced excitations in nanowire\ndevices made of perpendicular magnetic anisotropy (PMA) material. Our results\nshowed that upon including PMA the excitation of localized and propagating spin\nwave modes is feasible. We study the nature of the mode excitations as a\nfunction of the PMA strength (\\text{K}$_u$), and the current. Indeed, we\nestimate a critical value of \\text{K}$_u$ to allow for the excitation of the\npropagating spin wave. We attribute this mode selectivity between localized and\npropagating modes to a switch in the sign of the nonlinearity of the system\nfrom negative to positive at a non-zero \\text{K}$_u$ which is supported by\nanalytical calculations. Our results provide deep insight into engineering\nreconfigurable microwave devices for future magnonic and computational\napplications.",
        "positive": "Magnetization of a homogeneous two dimensional fermion gas with\n  repulsive contact interaction and Rashba spin-orbit potential: The z axis magnetization of a two dimensional electron gas with contact\nrepulsive interaction and in presence of a Rashba potential is computed by\nmeans of quantum field theory at second order. A striking effect of the pure\nRashba interaction is that of hindering spin alignment along the z direction.\nEvidence of transition at critical repulsive interaction coupling constant is\nstill found. The degree of magnetization, however, shows a clear dependence on\nthe spin-orbit interaction strength. Furthermore, the transition to magnetized\nstate appears to be smoothed by the presence of the Rashba interaction."
    },
    {
        "anchor": "Spin Properties of Very Shallow Nitrogen Vacancy Defects in Diamond: We investigate spin and optical properties of individual nitrogen-vacancy\ncenters located within 1-10 nm from the diamond surface. We observe stable\ndefects with a characteristic optically detected magnetic resonance spectrum\ndown to lowest depth. We also find a small, but systematic spectral broadening\nfor defects shallower than about 2 nm. This broadening is consistent with the\npresence of a surface paramagnetic impurity layer [Tisler et al., ACS Nano 3,\n1959 (2009)] largely decoupled by motional averaging. The observation of stable\nand well-behaved defects very close to the surface is critical for single-spin\nsensors and devices requiring nanometer proximity to the target.",
        "positive": "Magnetic Domain Wall Motion due to AC Bias-Driven Resonances: Most of the existing researches on the dynamics of a domain wall (DW) have\nfocused on the effect of DC biases, where the induced velocity is determined by\nthe bias strength. Here we show that AC biases such as a field or a current are\nalso able to move a DW via synchronization between the DW angle and the phase\nof the AC bias. The resulting DW velocity is proportional to the driving\nfrequency of the AC bias, but independent of the bias strength, offering\npotentially low-power operations of DW devices. The AC-bias-driven DW motion is\nshown to exhibit a phase locking-unlocking transition, a critical phenomenon\nakin to the Walker breakdown of a DC-bias-driven DW motion. Our work shows that\na DW can be driven resonantly by synchronizing its angle to AC biases, shedding\na light on hitherto overlooked utility of internal degree of freedom for\ndriving magnetic textures."
    },
    {
        "anchor": "Multi-mode Fabry-P\u00e9rot conductance oscillations in suspended\n  stacking-faults-free InAs nanowires: We report on observation of coherent electron transport in suspended\nhigh-quality InAs nanowire-based devices. The InAs nanowires were grown by\nlow-temperature gold-assisted vapor-liquid-solid molecular-beam-epitaxy. The\nhigh quality of the nanowires was achieved by removing the typically found\nstacking-faults and reducing possible Au incorporation. Minimizing\nsubstrate-induced scattering in the device was achieved by suspending the\nnanowires over predefined grooves. Coherent transport involving more than a\nsingle one-dimensional mode transport, was observed in the experiment,\nmanifested by Fabry-P\\'erot conductance oscillations. The length of the\nFabry-P\\'erot interferometer, deduced from the period of the conductance\noscillations, was found to be close to the physical length of the device. The\nhigh oscillations visibility imply nearly ballistic electron transport through\nthe nanowire.",
        "positive": "Flying electron spin control gates: The control of \"flying\" (or moving) spin qubits is an important functionality\nfor the manipulation and exchange of quantum information between remote\nlocations on a chip. Typically, gates based on electric or magnetic fields\nprovide the necessary perturbation for their control either globally or at\nwell-defined locations. Here, we demonstrate the dynamic control of moving\nelectron spins via contactless gates that move together with the spin. The\nconcept is realized using electron spins trapped and transported by moving\npotential dots defined by a surface acoustic wave (SAW). The SAW strain at the\nelectron trapping site, which is set by the SAW amplitude, acts as a\ncontactless, tunable gate that controls the precession frequency of the flying\nspins via the spin-orbit interaction. We show that the degree of precession\ncontrol in moving dots exceeds previously reported results for unconstrained\ntransport by an order of magnitude and is well accounted for by a theoretical\nmodel for the strain contribution to the spin-orbit interaction. This flying\nspin gate permits the realization of an acoustically driven optical\npolarization modulator based on electron spin transport, a key element for\non-chip spin information processing with a photonic interface."
    },
    {
        "anchor": "Adsorption geometry and electronic properties of flat-lying monolayers\n  of tetracene on the Ag(111) surface: The geometrical and electronic properties of the monolayer (ML) of tetracene\n(Tc) molecules on Ag(111) are systematically investigated by means of DFT\ncalculations with the use of localized basis set. The bridge and hollow\nadsorption positions of the molecule in the commensurate $\\gamma$-Tc/Ag(111)\nare revealed to be the most stable and equally favorable irrespective to the\napproximation chosen for the exchange-correlation functional. The binding\nenergy is entirely determined by the long-range dispersive interaction. The\nformer lowest unoccupied orbital remains being unoccupied in the case of\n$\\gamma$-Tc/Ag(111) as well as in the $\\alpha$-phase with increased coverage.\nThe unit cell of the $\\alpha$-phase with point-on-line registry was adapted for\ncalculations based on the available experimental data and the computed\nstructures of the $\\gamma$-phase. The calculated position of the Tc/Ag(111)\ninterface state is found to be noticeably dependent on the lattice constant of\nthe substrate, however its energy shift with respect to the Shockley surface\nstate of the unperturbed clean side of the slab is sensitive only to the\nadsorption distance and in good agreement with the experimentally measured\nenergy shift.",
        "positive": "Time-Reversal Symmetry Breaking Type-II Weyl State in YbMnBi2: Detection of Dirac, Majorana and Weyl fermions in real materials may\nsignificantly strengthen the bridge between high-energy and condensed-matter\nphysics. While the presence of Dirac fermions is well established in graphene\nand topological insulators, Majorana particles have been reported recently and\nevidence for Weyl fermions in non-centrosymmetric crystals has been found only\na couple of months ago, the 'magnetic' Weyl fermions are still elusive despite\nnumerous theoretical predictions and intense experimental search. In order to\ndetect a time-reversal symmetry breaking Weyl state we designed two materials\nwith Fermi velocities superior to that of graphene and present here the\nexperimental evidence of the realization of such a state in one of them,\nYbMnBi2. We model the time reversal symmetry breaking observed by magnetization\nmeasurements by a canted antiferromagnetic state and find a number of Weyl\npoints both above and below the Fermi level. Using angle-resolved\nphotoemission, we directly observe these latter Weyl points and a hallmark of\nthe exotic state - the arc of the surface states which connects these points.\nOur results not only provide a fundamental link between the two areas of\nphysics, but also demonstrate the practical way to design novel materials with\nexotic properties."
    },
    {
        "anchor": "Electrical detection of spin pumping due to the precessing magnetization\n  of a single ferromagnet: We report direct electrical detection of spin pumping, using a lateral normal\nmetal/ferromagnet/normal metal device, where a single ferromagnet in\nferromagnetic resonance pumps spin polarized electrons into the normal metal,\nresulting in spin accumulation. The resulting backflow of spin current into the\nferromagnet generates a d.c. voltage due to the spin dependent conductivities\nof the ferromagnet. By comparing different contact materials (Al and /or Pt),\nwe find, in agreement with theory, that the spin related properties of the\nnormal metal dictate the magnitude of the d.c. voltage.",
        "positive": "Visualizing dissipative charge carrier dynamics at the nanoscale with\n  superconducting charge qubit microscopy: The investigation of novel electronic phases in low-dimensional quantum\nmaterials demands for the concurrent development of new measurement techniques\nthat combine surface sensitivity with high spatial resolution and high\nmeasurement accuracy. We propose a new quantum sensing imaging modality based\non superconducting charge qubits to study dissipative charge carrier dynamics\nwith nanometer spatial and high temporal resolution. Using analytical and\nnumerical calculations we show that superconducting charge qubit microscopy\n(SCQM) has the potential to resolve temperature and resistivity changes in a\nsample as small as $\\Delta T\\leq0.1\\;$mK and $\\Delta\\rho\\leq1\\cdot10^{4}\n\\,\\Omega\\cdot$cm, respectively. Among other applications, SCQM will be\nespecially suited to study the microscopic mechanisms underlying interaction\ndriven quantum phase transitions, to investigate the boundary modes found in\nnovel topological insulators and, in a broader context, to visualize the\ndissiaptive charge carrier dynamics occurring in mesoscopic and nanoscale\ndevices."
    },
    {
        "anchor": "Tunable giant magnetoresistance in a single-molecule junction: Controlling electronic transport through a single-molecule junction is\ncrucial for molecular electronics or spintronics. In magnetic molecular\ndevices, the spin degree-of-freedom can be used to this end since the magnetic\nproperties of the magnetic ion centers fundamentally impact the transport\nthrough the molecules. Here we demonstrate that the electron pathway in a\nsingle-molecule device can be selected between two molecular orbitals by\nvarying a magnetic field, giving rise to a tunable anisotropic\nmagnetoresistance up to 93%. The unique tunability of the electron pathways is\ndue to the magnetic reorientation of the transition metal center, resulting in\na re-hybridization of molecular orbitals. We obtain the tunneling electron\npathways by Kondo effect, which manifests either as a peak or a dip line shape.\nThe energy changes of these spin-reorientations are remarkably low and less\nthan one millielectronvolt. The large tunable anisotropic magnetoresistance\ncould be used to control electronic transport in molecular spintronics.",
        "positive": "Spin diffusion and magnetoresistance in\n  ferromagnet/topological-insulator junctions: We study spin and charge diffusion in\nmetallic-ferromagnet/topological-insulator junctions. The coupled diffusion\nequations are derived perturbatively with respect to the strength of the\ninterlayer tunneling. We calculate spin accumulation in the ferromagnet and\njunction magnetoresistance associated with a current bias along the interface."
    },
    {
        "anchor": "Multichannel effects in Rashba quantum wires: We investigate intersubband mixing effects in multichannel quantum wires in\nthe presence of Rashba spin-orbit coupling and attached to two terminals. When\nthe contacts are ferromagnetic and their magnetization direction is\nperpendicular to the Rashba field, the spin-transistor current is expected to\ndepend in a oscillatory way on the Rashba coupling strength due to spin\ncoherent oscillations of the travelling electrons. Nevertheless, we find that\nthe presence of many propagating modes strongly influences the spin precession\neffect, leading to (i) a quenching of the oscillations and (ii) strongly\nirregular curves for high values of the Rashba coupling. We also observe that\nin the case of leads' magnetization parallel to the Rashba field, the\nconductance departs from a uniform value as the Rashba strength increases. We\nalso discuss the Rashba interaction induced current polarization effects when\nthe contacts are not magnetic and investigate how this mechanism is affected by\nthe presence of several propagating channels.",
        "positive": "Magnetic Field Effect on Strained Graphene Junctions: We investigate the spin-dependent transport properties of a\nferromagnetic/strained/normal graphene junctions with central region subjected\nto a magnetic field $B$. An analytical approach, based on Dirac equation, is\nimplemented to obtain the eigenstates and eigenvalues of the charge carrier in\nthree regions. Using the transfer matrix method, we determine the\nspin-dependent transmission in the presence of an applied strain along the\narmchair and zigzag directions of the graphene sample. We find that the strain\nremarkably modifies the Landau levels (LLs) originating from the applied $B$.\nIt is shown that the spin up/down energy bands, in the first region, are\nshifted by the exchange $H_{ex}$ and left the whole spectrum linear as in the\ncase of pristine graphene. In the central region, the position of the Dirac\npoint changes due to the uniaxial strain and $B$. It is also found that the\nuniaxial strain in graphene induces a contraction of the LLs spectra. Moreover,\nthe strain and $B$ modify the shape and position of some peaks in the\ntransmission probabilities."
    },
    {
        "anchor": "Hubbard ring: currents induced by change of magnetic flux: We investigate currents in a quantum ring threaded by a magnetic flux which\ncan be varied in an arbitrary way from an initial value $\\phi_i$ at time $t_i$\nto a final value $\\phi_f$ at time $t_f$. Dynamics of electrons in the ring is\ndescribed by the Hubbard and the extended Hubbard models. We demonstrate that\ntime dependence of the induced current bears information on electron\ncorrelations. In the case of the Hubbard model with infinite on--site repulsion\nwe prove that the current for $t>t_f$ is independent of the flux variation\nbefore $t_f$. Additionally, this current is fully determined by a solution of\nthe initial equilibrium problem and the value of $\\phi_f$. Apart from\nmesoscopic rings our results pose important implications for designing of\nquantum motors built out as the ring--shaped optical lattice.",
        "positive": "Dynamical polarization, plasmon model, and the Friedel oscillation of\n  the screened potential in doped Dirac and Weyl system: We discuss the dynamical polarization, plasmon dispersion, relaxation time,\nand the Friedel oscillation of screened potential of the two-dimension Dirac\nand three-dimension Weyl system (which are gapped) in the low-energy\ntigh-binding model. The results, like the Fermi wavevector, Thomas-Fermi\nwavevector, and longitudinal conductivity are obtained in different dimensions.\nSome important conclusions are detailedly discussed in this paper, including\nthe screening character under short or long range Coulomb interaction, and the\nlongitudinal conductivity in two- or three-dimensions. The longitudinal\nconductivity in optical limit is distinguishing for the case of two-dimension\nsystem and three-dimension system. The density-dependence (including the\ncarrier density and the impurity concentration) of the Fermi wavevector, dc\nconductivity, and the relaxation time are discussed. Specially, for the doped\nWeyl system, the pumped carrier density due to the chiral anomaly origin from\nelectromagnetic response is controlled by the internode relaxation time which\nhas also been analyzed. %The model for which the calculations based on is the\nlow-energy tight-binding model as presented in the Sec.2, %i.e., the results in\nthis paper is for the low-temperature and low-energy case %and it's thus\npossible to carrying out a logarithmic self-energy correction to the relaxation\ntime as we discussed in the text. %The difference between the longitudinal\nconductivity in serversal systems is also been discussed. Our results is\nhelpful to the application of the Dirac or Weyl systems as well as the study on\ntheir low-temperature characters."
    },
    {
        "anchor": "THz radiation induced circular Hall effect in graphene: We report on the observation of the circular transversal terahertz\nphotoconductivity in monolayer graphene supplied by a back gate. The\nphotoconductivity response is caused by the free carrier absorption and\nreverses its sign upon switching the radiation helicity. The observed dc Hall\neffect manifests the time inversion symmetry breaking induced by circularly\npolarized terahertz radiation in the absence of a magnetic field. For low gate\nvoltages, the photosignal is found to be proportional to the radiation\nintensity and can be ascribed to the alignment of electron momenta by the\ncombined action of THz and static electric fields as well as by the dynamic\nheating and cooling of the electron gas. Strikingly, at high gate voltages, we\nobserve that the linear-in-intensity Hall photoconductivity vanishes; the\nphotoresponse at low intensities becomes superlinear and varies with the square\nof the radiation intensity. We attribute this behavior to the interplay of the\nsecond- and fourth-order effects in the radiation electric field which has not\nbeen addressed theoretically so far and requires additional studies.",
        "positive": "Particle-hole asymmetry on Hall conductivity of a topological insulator: The helical Dirac states on the surface of a topological insulator are\nprotected by topology and display significant particle-hole asymmetry. This\nasymmetry arises from a subdominant Schr\\\"{o}dinger type contribution to the\nHamiltonian which provides a small perturbation to a dominant Dirac\ncontribution. This changes the Landau levels energies in an external magnetic\nfield ($B$) and provides modifications to the usual relativistic optical matrix\nelements. Nevertheless we find that the relativistic quantization of the Hall\nplateaux remains even when the ratio of the Schr\\\"{o}dinger ($E_0$) to Dirac\n($E_1$) magnetic energy scale increases either through an increase in $B$, a\ndecrease in the Schr\\\"{o}dinger mass or of the Dirac fermi velocity. First\ncorrections to the optical matrix elements(OME) in the relativistic case drop\nout at least to order $(E_0/E_1)^3$. In the opposite limit $E_1$ small, the\nquantization remains classical but there is a split into two series. The first\ncorrections to the OME in this case, cancel out at least to order\n$(E_1/E_0)^4$."
    },
    {
        "anchor": "Dynamical piezoelectric and magnetopiezoelectric effects in polar metals\n  from Berry phases and orbital moments: The polarization of a material and its response to applied electric and\nmagnetic fields are key solid-state properties with a long history in\ninsulators, although a satisfactory theory required new concepts such as\nBerry-phase gauge fields. In metals, quantities such as static polarization and\nmagnetoelectric $\\theta$-term cease to be well-defined. In polar metals there\ncan be analogous dynamical current responses, which we study in a common\ntheoretical framework. We find that current responses to dynamical strain in\npolar metals depend on both the first and second Chern forms, related to\npolarization and magnetoelectricity in insulators, as well as the orbital\nmagnetization on the Fermi surface. We provide realistic estimates that predict\nthat the latter contribution will dominate and investigate the feasibility of\nexperimental detection of this effect.",
        "positive": "Imaging three-dimensional nanoscale magnetization dynamics: The ability to experimentally map the three-dimensional structure and\ndynamics in bulk and patterned three-dimensional ferromagnets is essential both\nfor understanding fundamental micromagnetic processes, as well as for\ninvestigating technologically-relevant micromagnets whose functions are\nconnected to the presence and dynamics of fundamental micromagnetic structures,\nsuch as domain walls and vortices. Here, we demonstrate time-resolved magnetic\nlaminography, a technique which offers access to the temporal evolution of a\ncomplex three-dimensional magnetic structure with nanoscale resolution. We\nimage the dynamics of the complex three-dimensional magnetization state in a\ntwo-phase bulk magnet with a lateral spatial resolution of 50 nm, mapping the\ntransition between domain wall precession and the dynamics of a uniform\nmagnetic domain that is attributed to variations in the magnetization state\nacross the phase boundary. The capability to probe three-dimensional magnetic\nstructures with temporal resolution paves the way for the experimental\ninvestigation of novel functionalities arising from dynamic phenomena in bulk\nand three-dimensional patterned nanomagnets."
    },
    {
        "anchor": "Photovoltaic and Rectification Currents in Quantum Dots: We investigate theoretically and experimentally the statistical properties of\ndc current through an open quantum dot subject to ac excitation of a\nshape-defining gate. The symmetries of rectification current and photovoltaic\ncurrent with respect to applied magnetic field are examined. Theory and\nexperiment are found to be in good agreement throughout a broad range of\nfrequency and ac power, ranging from adiabatic to nonadiabatic regimes.",
        "positive": "Asymmetric double barrier resonant tunneling structures with improved\n  characteristics: We present a self-consistent calculation, based on the global coherent\ntunnelling model, and show that structural asymmetry of double barrier resonant\ntunnelling structures significantly modifies the current-voltage\ncharacteristics compared to the symmetric structures. In particular, a suitably\ndesigned asymmetric structure can produce much larger peak current and absolute\nvalue of the negative differential conductivity than its commonly used\nsymmetric counterpart."
    },
    {
        "anchor": "Shaping electron wave functions in a carbon nanotube with a parallel\n  magnetic field: A magnetic field, through its vector potential, usually causes measurable\nchanges in the electron wave function only in the direction transverse to the\nfield. Here we demonstrate experimentally and theoretically that in carbon\nnanotube quantum dots, combining cylindrical topology and bipartite hexagonal\nlattice, a magnetic field along the nanotube axis impacts also the longitudinal\nprofile of the electronic states. With the high (up to 17T) magnetic fields in\nour experiment the wave functions can be tuned all the way from \"half-wave\nresonator\" shape, with nodes at both ends, to \"quarter-wave resonator\" shape,\nwith an antinode at one end. This in turn causes a distinct dependence of the\nconductance on the magnetic field. Our results demonstrate a new strategy for\nthe control of wave functions using magnetic fields in quantum systems with\nnontrivial lattice and topology.",
        "positive": "Coupling a quantum dot, fermionic leads and a microwave cavity on-chip: We demonstrate a hybrid architecture consisting of a quantum dot circuit\ncoupled to a single mode of the electromagnetic field. We use single wall\ncarbon nanotube based circuits inserted in superconducting microwave cavities.\nBy probing the nanotube-dot using a dispersive read-out in the Coulomb blockade\nand the Kondo regime, we determine an electron-photon coupling strength which\nshould enable circuit QED experiments with more complex quantum dot circuits."
    },
    {
        "anchor": "Breakdown of the Wiedemann-Franz law in AB-stacked bilayer graphene: We present a simple theory of thermoelectric transport in bilayer graphene\nand report our results for the electrical resistivity, the thermal resistivity,\nthe Seebeck coefficient, and the Wiedemann-Franz ratio as functions of doping\ndensity and temperature. In the absence of disorder, the thermal resistivity\ntends to zero as the charge neutrality point is approached; the electric\nresistivity jumps from zero to an intrinsic finite value, and the Seebeck\ncoefficient diverges in the same limit. Even though these results are similar\nto those obtained for single-layer graphene, their derivation is considerably\nmore delicate. The singularities are removed by the inclusion of a small amount\nof disorder, which leads to the appearance of a \"window\" of doping densities\n$0<n<n_c$ (with $n_c$ tending to zero in the zero-disorder limit) in which the\nWiedemann-Franz law is severely violated.",
        "positive": "Selective transmission of Dirac electrons and ballistic\n  magnetoresistance of \\textit{n-p} junctions in graphene: We show that an electrostatically created n-p junction separating the\nelectron and hole gas regions in a graphene monolayer transmits only those\nquasiparticles that approach it almost perpendicularly to the n-p interface.\nSuch a selective transmission of carriers by a single n-p junction would\nmanifest itself in non-local magnetoresistance effect in arrays of such\njunctions and determines the unusual Fano factor in the current noise universal\nfor the n-p junctions in graphene."
    },
    {
        "anchor": "Dynamical phase transition in vibrational surface modes: We consider the dynamical properties of a simple model of vibrational surface\nmodes. We obtain the exact spectrum of surface excitations and discuss their\ndynamical features. In addition to the usually discussed localized and\noscillatory regimes we also find a second phase transition where surface mode\nfrequency becomes purely imaginary and describes an overdamped regime.\nNoticeably, this transition has an exact correspondence to the oscillatory -\noverdamped transition of the standard oscillator with a frictional force\nproportional to velocity.",
        "positive": "Electrically Tunable Band Gap in Silicene: We report calculations of the electronic structure of silicene and the\nstability of its weakly buckled honeycomb lattice in an external electric field\noriented perpendicular to the monolayer of Si atoms. We find that the electric\nfield produces a tunable band gap in the Dirac-type electronic spectrum, the\ngap being suppressed by a factor of about eight by the high polarizability of\nthe system. At low electric fields, the interplay between this tunable band\ngap, which is specific to electrons on a honeycomb lattice, and the Kane-Mele\nspin-orbit coupling induces a transition from a topological to a band\ninsulator, whereas at much higher electric fields silicene becomes a semimetal."
    },
    {
        "anchor": "Tunable electrochemistry with moir\u00e9 flat bands and topological defects\n  at twisted bilayer graphene: Tailoring electron transfer dynamics across solid-liquid interfaces is\nfundamental to the interconversion of electrical and chemical energy. Stacking\natomically thin layers with a very small azimuthal misorientation to produce\nmoir\\'e superlattices enables the controlled engineering of electronic band\nstructures and the formation of extremely flat electronic bands. Here, we\nreport a strong twist angle dependence of heterogeneous charge transfer\nkinetics at twisted bilayer graphene electrodes with the greatest enhancement\nobserved near the 'magic angle' (~1.1 degrees). This effect is driven by the\nangle-dependent tuning of moir\\'e-derived flat bands that modulate electron\ntransfer processes with the solution-phase redox couple. Combined experimental\nand computational analysis reveals that the variation in electrochemical\nactivity with moir\\'e angle is controlled by atomic reconstruction of the\nmoir\\'e superlattice at twist angles <2 degrees, and topological defect AA\nstacking regions produce a large anomalous local electrochemical enhancement\nthat cannot be accounted for by the elevated local density of states alone. Our\nresults introduce moir\\'e flat band materials as a distinctively tunable\nparadigm for mediating electrochemical transformations.",
        "positive": "Eight fold quantum Hall phases in a time reversal symmetry broken tight\n  binding model: We consider a time reversal symmetry (TRS) broken Kane-Mele model\nsuperimposed with Haldane model and chart out the phase diagram using spin\nChern number to investigate the fate of quantum anomalous Hall insulator (QAHI)\nand quantum spin Hall insulator (QSHI) phases. Interestingly, in addition to\nQSHI and QAHI phase, the phase diagram unveils quantum anomalous spin Hall\ninsulator (QASHI) phase where only one spin sector is topological. We also find\nmulticritical points where three / four topological phase boundaries coalesce.\nThese topological phases are protected by an effective TRS and a composite\nanti-unitary particle-hole symmetry leading to remarkable properties of edge\nmodes. We find spin-selective, spin-polarized and spin-neutral edge transport\nin QASHI, QSHI and QAHI phases respectively. Our study indicates that the\nrobustness of the topological phase mainly depends on the spin gap which does\nnot necessarily vanish at the Dirac points across a topological phase\ntransition. We believe that our proposals can be tested in near future using\nrecent experimental advancements in solid state and cold atomic systems."
    },
    {
        "anchor": "Nonlocality, Correlations, and Magnetotransport in a Spatially Modulated\n  Two-Dimensional Electron Gas: It is shown that the classical commensurability phenomena in weakly modulated\ntwo-dimensional electron systems is a manifestation of the intrinsic properties\nof the correlation functions describing a homogeneous electron gas in a\nmagnetic field. The theory demonstrates the importance for consideration of\nnonlocal response and removes the gap between classical and quantum approaches\nto magnetotransport in such systems.",
        "positive": "A high performance Nb nano-SQUID with a three-dimensional structure: A superconducting quantum interference device (SQUID) miniaturized into\nnanoscale is promising in the inductive detection of a single electron spin. A\nnano-SQUID with a strong spin coupling coefficient, a low flux noise, and a\nwide working magnetic field range is highly desired in a single spin resonance\nmeasurement. Nano-SQUIDs with Dayem-bridge junctions excel in a high working\nfield range and in the direct coupling from spins to the bridge. However, the\ncommon planar structure of nano-SQUIDs is known for problems such as a shallow\nflux modulation depth and a troublesome hysteresis in current-voltage curves.\nHere, we developed a fabrication process for creating three-dimensional (3-D)\nniobium (Nb) nano-SQUIDs with nano-bridge junctions that can be tuned\nindependently. Characterization of the device shows up to 45.9 % modulation\ndepth with a reversible current-voltage curve. Owning to the large modulation\ndepth, the measured flux noise is as low as 0.34 \\mu\\Phi$_0$/Hz$^{1/2}$. The\nworking field range of the SQUID is greater than 0.5 T parallel to the SQUID\nplane. We believe that 3-D Nb nano-SQUIDs provide a promising step toward\neffective single-spin inductive detection."
    },
    {
        "anchor": "Graphene Quantum Dot with Divacancy and Topological Defects: A Novel\n  Material for Promoting Prompt and Delayed Fluorescence of Tunable Wavelengths: This work demonstrates the unique approach of introducing divacancy\nimperfections in topological Stone-Wales type defected graphene quantum dots\nfor harvesting both singlet and triplet excitons, essential for fabricating\nfluorescent organic light-emitting diodes. Here, we first reveal that\nstructural relaxation of these systems establishes the high-spin triplet state\nas the stable ground state at room temperature, thereby significantly\nincreasing their potential in designing spintronic devices. Our extensive\nelectron-correlated computations then demonstrate that the energetic ordering\nof the singlet and triplet states in these relaxed structures can trigger both\nprompt and delayed fluorescence of different wavelengths through various decay\nchannels. Particularly, the position of divacancy determines the tunability\nrange of the emission wavelengths. In addition, our results obtained from both\nmulti-reference singles-doubles configurationinteraction (MRSDCI) and\nfirst-principles time-dependent density functional theory (TDDFT) methodologies\nhighlight that the synergetic effects of divacancy-position,structural\nrelaxation and spin multiplicity critically govern the nature and magnitude of\nshift exhibited by the most intense peak of the absorption profile, crucial for\ndesigning optoelectronic devices.",
        "positive": "Generation of magnetic skyrmion bubbles by inhomogeneous spin Hall\n  currents: Recent experiments have shown that magnetic skyrmion bubbles can be generated\nand injected at room temperature in thin films [W. Jiang et al, Science vol.\n349, 283 (2015)]. Here, we demonstrate, using micromagnetic modeling, that such\nskyrmions can be generated by an inhomogeneous spin Hall torque in the presence\nof Dzyaloshinskii-Moriya interactions (DMIs). In the experimental\nTa/Co$_{20}$Fe$_{60}$B$_{20}$ thin films, the DMI is rather small;\nnevertheless, the skyrmion bubbles are stable, or at least metastable on\nobservational time scales."
    },
    {
        "anchor": "Coupled quantum wires: We study a set of crossed 1D systems, which are coupled with each other via\ntunnelling at the crossings. We begin with the simplest case with no\nelectron-electron interactions and find that besides the expected level\nsplitting, bound states can emerge. Next, we include an external potential and\nelectron-electron interactions, which are treated within the Hartree\napproximation. Then, we write down a formal general solution to the problem,\ngiving additional details for the case of a symmetric external potential.\nConcentrating on the case of a single crossing, we were able to explain recent\nexperinents on crossed metallic and semiconducting nanotubes [J. W. Janssen, S.\nG. Lemay, L. P. Kouwenhoven, and C. Dekker, Phys. Rev. B 65, 115423 (2002)],\nwhich showed the presence of localized states in the region of crossing.",
        "positive": "Analytical expression of negative differential thermal resistance in a\n  macroscopic heterojunction: Heat flux ($J$) generally increases with temperature difference in a\nmaterial. A differential coefficient of $J$ against temperature ($T$) is called\ndifferential thermal conductance ($k$), and an inverse of $k$ is differential\nthermal resistance ($r$). Although $k$ and $r$ are generally positive, they can\nbe negative in a macroscopic heterojunction with positive $T$-dependent\ninterfacial thermal resistance (ITR). The negative differential thermal\nresistance (NDTR) effect is an important effect that can realize thermal\ntransistor, thermal memory, and thermal logic gate. In this paper, we examine\nanalytical expressions of $J$, $k$, $r$, and other related quantities as a\nfunction of parameters related to thermal conductivity ($\\kappa$) and ITR in a\nmacroscopic heterojunction to precisely describe the NDTR effect."
    },
    {
        "anchor": "Quantum time mirrors for general two-band systems: Methods that are devised to achieve reversal of quantum dynamics in time have\nbeen named \"quatum time mirrors\". Such a time mirror can be considered as a\ngeneralization of Hahn's spin echo to systems with continuous degrees of\nfreedom. We extend the quantum time mirror protocol originally proposed for\nDirac dispersions to arbitrary two-band systems and establish the general\nrequirements for its efficient implementation. We further discuss its\nsensitivity to various non- homogeneous perturbations including disorder\npotentials and the effect of external static magnetic and electric fields. Our\ngeneral statements are verified for a number of exemplary Hamiltonians, whose\nphase-coherent dynamics are studied both analytically and numerically. The\nHamiltonians considered can be used to describe the low-energy properties of\nsystems as diverse as cold atom- optics setups, direct band gap semiconductors\nor (mono- or bilayer) graphene. We discuss the consequences of many-body\neffects at a qualitative level, and consider the protocol feasibility in\nstate-of-the-art experimental setups.",
        "positive": "Single-Electron Transistor in Strained Si/SiGe Heterostructures: A split gate technique is used to form a lateral quantum dot in a\ntwo-dimensional electron gas of a modulation-doped silicon/silicon-germanium\nheterostructure. e-beam lithography was employed to produce split gates. By\napplying negative voltages to these gates the underlying electron gas is\ndepleted and a lateral quantum dot is formed, the size of which can be adjusted\nby the gate voltage. We observe single-electron operation with Coulomb blockade\nbehavior below 1K. Gate leakage currents are well controlled, indicating that\nthe recently encountered problems with Schottky gates for this type of\napplication are not an inherent limitation of modulation-doped Si/SiGe\nheterostructures, as had been speculated."
    },
    {
        "anchor": "Field enhancement in subnanometer metallic gaps: Motivated by recent experiments [Ward et al., Nature Nanotech. 5, 732\n(2010)], we present here a theoretical analysis of the optical response of\nsharp gold electrodes separated by a subnanometer gap. In particular, we have\nused classical finite difference time domain simulations to investigate the\nelectric field distribution in these nanojunctions upon illumination. Our\nresults show a strong confinement of the field within the gap region, resulting\nin a large enhancement compared to the incident field. Enhancement factors\nexceeding 1000 are found for interelectrode distances on the order of a few\nangstroms, which are fully compatible with the experimental findings. Such huge\nenhancements originate from the coupling of the incident light to the\nevanescent field of hybrid plasmons involving charge density oscillations in\nboth electrodes.",
        "positive": "Control of threshold voltages in Si/SiGe quantum devices via optical\n  illumination: Optical illumination of quantum-dot qubit devices at cryogenic temperatures,\nwhile not well studied, is often used to recover operating conditions after\nundesired shocking events or charge injection. Here, we demonstrate systematic\nthreshold voltage shifts in a dopant-free, Si/SiGe field effect transistor\nusing a near infrared (780 nm) laser diode. We find that illumination under an\napplied gate voltage can be used to set a specific, stable, and reproducible\nthreshold voltage that, over a wide range in gate bias, is equal to that gate\nbias. Outside this range, the threshold voltage can still be tuned, although\nthe resulting threshold voltage is no longer equal to the applied gate bias\nduring illumination. We present a simple and intuitive model that provides a\nmechanism for the tunability in gate bias. The model presented also explains\nwhy cryogenic illumination is successful at resetting quantum dot qubit devices\nafter undesired charging events."
    },
    {
        "anchor": "Silicon Donor Array as a Disordered One-Dimensional Electron Gas: Donors in silicon can now be positioned with an accuracy of about one lattice\nconstant, making it possible in principle to form donor arrays for quantum\ncomputation or quantum simulation applications. However the multi-valley\ncharacter of the silicon conduction band combines with central cell corrections\nto the donor state Hamiltonian to translate atomic scale imperfections in donor\nplacement into strongly disordered inter-donor hybridization. We present a\nsimple model that is able to account accurately for central-cell corrections,\nand use it to assess the impact of donor-placement disorder on donor array\nproperties in both itinerant and localized limits.",
        "positive": "Silicon on a graphene nanosheet with triangle- and dot-shape: Electronic\n  structure, specific heat, and thermal conductivity from first-principle\n  calculations: The electronic structure, specific heat, and thermal conductivity of silicon\nembedded in a monolayer graphene nanosheet are studied using Density Functional\nTheory. Two different shapes of the substitutional Si doping in the graphene\nare studied, a triangular and a dot shape. The silicon doping of a graphene\nnanosheet, with the silicon atoms arranged in a triangular configuration in\northo- and para-positions, opens up a band gap transforming the sheet to a\nsemiconducting material. The opening of the band gap is caused by the presence\nof the repulsion force between the silicon and carbon atoms decreasing the\ndensity of states around the Fermi energy. Consequently, the specific heat and\nthe thermal conductivity of the system are suppressed. For graphene nanosheet\ndoped with a dot-like configuration of silicon atoms, at the ortho-, meta-, and\npara-positions, the valence band crosses the Fermi level. This doping\nconfiguration increases the density of state at the Fermi level, but mobile\ncharge are delocalized and diminished around the silicon atoms. As a result,\nthe specific heat and the thermal conductivity are enhanced. Silicon\nsubstitutionally doped graphene nanosheets may be beneficial for photovoltaics\nand can further improve solar cell devices by controlling the geometrical\nconfiguration of the underlying atomic systems."
    },
    {
        "anchor": "Exact analytical solution of a time-reversal-invariant topological\n  superconducting wire: We consider a model proposed before for a time-reversal-invariant topological\nsuperconductor (TRITOPS) which contains a hopping term $t$, a chemical\npotential $\\mu$, an extended $s$-wave pairing $\\Delta$ and spin-orbit coupling\n$\\lambda$. We show that for $|\\Delta|=|\\lambda|$, $\\mu=t=0$, the model can be\nsolved exactly defining new fermion operators involving nearest-neighbor sites.\nThe many-body ground state is four-fold degenerate due to the existence of two\nzero-energy modes localized exactly at the first and the last site of the\nchain. These four states show entanglement in the sense that creating or\nannihilating a zero-energy mode at the first site is proportional to a similar\noperation at the last site. By continuity, this property should persist for\ngeneral parameters. Using these results we correct some statements related with\nthe so called \"time-reversal anomaly\". Addition of a small hopping term for a\nchain with an even number of sites breaks the degeneracy and the ground state\nbecomes unique with an even number of particles. We also consider a small\nmagnetic field applied to one end of the chain. We compare the many-body\nexcitation energies and spin projection along the spin-orbit direction for both\nends of the chains with numerical results %for a small chain obtaining good\nagreement.",
        "positive": "First-principle studies of the spin-orbit and the Dzyaloshinskii-Moriya\n  interactions in the \\{Cu$_3$\\} single-molecule magnet: Frustrated triangular molecule magnets such as \\{Cu$_3$\\} are characterized\nby two degenerate S=1/2 ground-states with opposite chirality. Recently it has\nbeen proposed theoretically [PRL {\\bf 101}, 217201 (2008)] and verified by {\\it\nab-initio} calculations [PRB {\\bf 82}, 155446 (2010)] that an external electric\nfield can efficiently couple these two chiral spin states, even in the absence\nof spin-orbit interaction (SOI). The SOI is nevertheless important, since it\nintroduces a splitting in the ground-state manifold via the\nDzyaloshinskii-Moriya interaction. In this paper we present a theoretical study\nof the effect of the SOI on the chiral states within spin density functional\ntheory. We employ a recently-introduced Hubbard model approach to elucidate the\nconnection between the SOI and the Dzyaloshinskii-Moriya interaction. This\nallows us to express the Dzyaloshinskii-Moriya interaction constant $D$ in\nterms of the microscopic Hubbard model parameters, which we calculate from\nfirst-principles. The small splitting that we find for the \\{Cu$_3$\\} chiral\nstate energies ($\\Delta \\approx 0.02$ meV) is consistent with experimental\nresults. The Hubbard model approach adopted here also yields a better estimate\nof the isotropic exchange constant than the ones obtained by comparing total\nenergies of different spin configurations. The method used here for calculating\nthe DM interaction unmasks its simple fundamental origin which is the\noff-diagonal spin-orbit interaction between the generally multireference vacuum\nstate and single-electron excitations out of those states."
    },
    {
        "anchor": "Synthesizing and Controlling Helical Indirect Exchange Interactions at\n  Nonequilibrium: We study the nonequilibrium effects of spin and/or electric currents on the\nhelical indirect exchange interactions of local spins that embedded in general\nopen electronic systems. Especially, besides the synthesized anisotropic\nHeisenberg interactions, we find that the synthetic helical indirect exchange\ninteractions possess two parts: antisymmetric (Dzyaloshinskii-Moriya\ninteraction) and symmetric (Kaplan-Shekhtman-Entin-Wohlman-Aharony\ninteraction), which are all formulated in terms of Keldysh nonequilibrium\nGreen's functions. The presence of either spin-orbit coupling or spin polarized\ncurrents alone is able to synthesize and control the antisymmetric\nDzyaloshinskii-Moriya exchange interactions, as the same direction as spin\nsplitting. However, the appearance of symmetric\nKaplan-Shekhtman-Entin-Wohlman-Aharony interactions requires both, i.e., the\nspin-orbit coupling and spin polarized currents with different splitting\ndirections. Our results show the detailed scheme of controlling the sign,\nmagnitude, and direction of indirect Dzyaloshinskii-Moriya vectors and\nKaplan-Shekhtman-Entin-Wohlman-Aharony interactions at nonequilibrium in open\nquantum devices.",
        "positive": "Inelastic effects in molecular transport junctions: The probe technique\n  at high bias: We extend the Landauer-B\\\"uttiker probe formalism for conductances to the\nhigh bias regime, and study the effects of environmentally-induced elastic and\ninelastic scattering on charge current in single molecule junctions, focusing\non high-bias effects. The probe technique phenomenologically incorporates\nincoherent elastic and inelastic effects to the fully coherent case, mimicking\na rich physical environment at trivial cost. We further identify\nenvironmentally-induced mechanisms which generate an asymmetry in the current,\nmanifested as a weak diode behavior. This rectifying behavior, found in two\ntypes of molecular junction models, is absent in the coherent-elastic limit,\nand is only active in the case with incoherent-inelastic scattering. Our work\nillustrates that in the low bias - linear response regime, the commonly used\n\"dephasing probe\" (mimicking only elastic decoherence effects) operates nearly\nindistinguishably from a \"voltage probe\" (admitting inelastic-dissipative\neffects). However, these probes realize fundamentally distinct $I$-$V$\ncharacteristics at high biases, reflecting the central roles of dissipation and\ninelastic scattering processes on molecular electronic transport\nfar-from-equilibrium."
    },
    {
        "anchor": "Macroscopic Coherent Rectification in Andreev Interferometers: We investigate nonlinear transport through quantum coherent metallic\nconductors contacted to superconducting components. We find that in certain\ngeometries, the presence of superconductivity generates a large, finite-average\nrectification effect. Specializing to Andreev interferometers, we show that the\ndirection and magnitude of rectification can be controlled by a magnetic flux\ntuning the superconducting phase difference at two contacts. In particular,\nthis results in the breakdown of an Onsager reciprocity relation at finite\nbias. The rectification current is macroscopic in that it scales with the\nlinear conductance, and we find that it exceeds 5% of the linear current at\nsub-gap biases of few tens of \\mu eV's.",
        "positive": "Zero-bias conductance anomaly in bilayer quantum Hall systems: Bilayer quantum Hall system at total filling factor $\\nu=1$ shows a rich\nvariety of broken symmetry ground states because of the competition between the\ninterlayer and intralayer Coulomb interactions. When the layers are\nsufficiently close, a bilayer system develops spontaneous interlayer\nphase-coherence that manifests itself through a spectacular enhancement of the\nzero-bias interlayer tunneling conductance. We present a theory of this\ntunneling conductance anomaly, and show that the zero-bias conductance is\nproportional to the square of the {\\it quasiparticle} tunneling amplitude."
    },
    {
        "anchor": "Is silicene stable in air? -- First principles study of oxygen\n  adsorption and dissociation on silicene: The oxygen adsorption and dissociation on pristine silicene surface are\nstudied by use of first-principles in this letter. The oxygen adsorption and\ndissociation on pristine silicene surface are studied by use of\nfirst-principles in this letter. It is found that the pristine silicene is not\nstable in air because the oxygen molecule can be easily adsorbed and\ndissociated into two O atoms without overcoming any energy barrier on pristine\nsilicene surface. In addition, dissociated oxygen atoms are relatively\ndifficult to migrate on or desorbed from pristine silicene surface, leading to\npoor mobility of oxygen atom. As a result, silicene would be changed into Si-O\ncompounds in air. The work will be helpful to reveal the detail of the\ninteraction between oxygen molecules and pristine silicene surface, especially\nhelpful to understand the stability of silicene in air.",
        "positive": "Anisotropy in Ferromagnetic Nanoparticles: Level-to-Level Fluctuations\n  of a Collective Effect: We calculate the mesoscopic fluctuations of the magnetic anisotropy of\nferromagnetic nanoparticles. A microscopic spin-orbit Hamiltonian considered as\na perturbation of the much stronger exchange interaction first yields an\nexplicit expression for the anisotropy tensor. Then, assuming a simple random\nmatrix model for the spin-orbit coupling allows us to describe the fluctuation\nof such a tensor. In the case of uniaxial anisotropy, we calculate the\ndistribution of the anisotropy constant for a given number of electrons, and\nits variation upon increasing this number by one. The magnitude of the latter\nis sufficient to account for the experimental data."
    },
    {
        "anchor": "Anisotropies of the g-factor tensor and diamagnetic coefficient in\n  crystal-phase quantum dots in InP nanowires: Crystal-phase low-dimensional structures offer great potential for the\nimplementation of photonic devices of interest for quantum information\nprocessing. In this context, unveiling the fundamental parameters of the\ncrystal phase structure is of much relevance for several applications. Here, we\nreport on the anisotropy of the g-factor tensor and diamagnetic coefficient in\nwurtzite/zincblende (WZ/ZB) crystal-phase quantum dots (QDs) realized in single\nInP nanowires. The WZ and ZB alternating axial sections in the NWs are\nidentified by high-angle annular dark-field scanning transmission electron\nmicroscopy. The electron (hole) g-factor tensor and the exciton diamagnetic\ncoefficients in WZ/ZB crystal-phase QDs are determined through\nmicro-photoluminescence measurements at low temperature (4.2 K) with different\nmagnetic field configurations, and rationalized by invoking the spin-correlated\norbital current model. Our work provides key parameters for band gap\nengineering and spin states control in crystal-phase low-dimensional structures\nin nanowires.",
        "positive": "Field Theory of Mesoscopic Fluctuations in Superconductor/Normal-Metal\n  Systems: Thermodynamic and transport properties of normal disordered conductors are\nstrongly influenced by the proximity of a superconductor. A cooperation between\nmesoscopic coherence and Andreev scattering of particles from the\nsuperconductor generates new types of interference phenomena. We introduce a\nfield theoretic approach capable of exploring both averaged properties and\nmesoscopic fluctuations of superconductor/normal-metal systems.\n  As an example the method is applied to the study of the level statistics of a\nSNS-junction."
    },
    {
        "anchor": "Reduced and projected two-particle entanglement at finite temperatures: We present a theory for two-particle entanglement production and detection in\nmesoscopic conductors at finite temperature. In contrast to the zero\ntemperature limit, the entanglement of the density matrix projected out of the\nemitted many-body state is different from the entanglement of the reduced\ndensity matrix, detectable by current correlation measurements. We show that\nunder very general conditions the reduced entanglement constitutes a lower\nbound for the projected entanglement. Applying the theory to the recent\nexperiment [Neder et al, Nature 448 333 (2007)] on a fermionic Hanbury Brown\nTwiss two-particle interferometer we find that despite an appreciable\nentanglement production in the experiment, the detectable entanglement is close\nto zero.",
        "positive": "$^{13}$C NMR Study on Zero-Gap State in the Organic Conductor\n  $\u03b8$-(BEDT-TTF)$_{2}$I$_{3}$ under Pressure: We present the results of our $^{13}$C NMR study of the quasi-two-dimensional\norganic conductor $\\theta$-(BEDT-TTF)$_2$I$_{3}$ under pressure, which is\nsuggested to be a zero-gap conductor by transport measurements. We found that\nNMR spin shift is proportional to $T$ and that spin-lattice relaxation rate\nfollows the power law $T^{\\alpha}$ ($\\alpha =3 \\sim 4$), where $T$ is the\ntemperature. This behavior is consistent with the cone-like band dispersion and\nprovides microscopic evidence for the realization of the zero-gap state in the\npresent material under pressure."
    },
    {
        "anchor": "From an array of quantum wires to three-dimensional fractional\n  topological insulators: The coupled-wires approach has been shown to be useful in describing\ntwo-dimensional strongly interacting topological phases. In this manuscript we\nextend this approach to three-dimensions, and construct a model for a\nfractional strong topological insulator. This topologically ordered phase has\nan exotic gapless state on the surface, called a fractional Dirac liquid, which\ncannot be described by the Dirac theory of free fermions. Like in\nnon-interacting strong topological insulators, the surface is protected by the\npresence of time-reversal symmetry and charge conservation. We show that upon\nbreaking these symmetries, the gapped fractional Dirac liquid presents unique\nfeatures. In particular, the gapped phase that results from breaking\ntime-reversal symmetry has a halved fractional Hall conductance of the form\n$\\sigma_{xy}=\\frac{1}{2}\\frac{e^{2}}{mh}$ if the filling is $\\nu=1/m$. On the\nother hand, if the surface is gapped by proximity coupling to an $s$-wave\nsuperconductor, we end up with an exotic topological superconductor. To reveal\nthe topological nature of this superconducting phase, we partition the surface\ninto two regions: one with broken time-reversal symmetry and another coupled to\na superconductor. We find a fractional Majorana mode, which cannot be described\nby a free Majorana theory, on the boundary between the two regions. The density\nof states associated with tunneling into this one-dimensional channel is\nproportional to $\\omega^{m-1}$, in analogy to the edge of the corresponding\nLaughlin state.",
        "positive": "Polarization and polarization induced electric field in nitrides -\n  critical evaluation based on DFT studies: Density Functional Theory (DFT) calculations were used to evaluate polarity\nof group III nitrides, such as aluminum nitride (AlN), gallium nitride (GaN)\nand indium nitride (InN) providing physically sound quantitative measure of\npolarity of these materials. Two different approaches to polarization of\nnitride semiconductors were assessed and the conclusions have been used to\ndevelop models. It was shown that Berry phase formulation of the electron\nrelated polarization component provides a number of various solutions,\ndifferent for various selection of the simulated volume. The electronic part\ngives saw-like pattern for polarization. A total number of these solutions,\nrelated to well known scaling of the geometric phase, is equal to the number of\nvalence electrons in the system. Summation with similar pattern for ionic part\nprovides several polarization values. Standard dipole density formulation\ndepends on the selection of the simulation volume in periodic continuous way.\nUsing a condition of continuous embedding into the infinite medium, and\nsimultaneously, the zero surface charge representation at crystal boundary\nprovides to physically sound solution. This solution is corresponding to\nmaximal and minimal polarization values and also corresponds to different\nphysical termination of the crystal surfaces, either bare or covered by\ncomplementary atoms. This change leads to polarization and electric field\nreversal. The polarization and related fields in finite size systems were\nobtained."
    },
    {
        "anchor": "Single wall carbon nanotubes as coherent plasmon generators: The possibility of low-energy surface plasmon amplification by optically\nexcited excitons in small-diameter single wall carbon nanotubes is\ntheoretically demonstrated. The nonradiative exciton-plasmon energy transfer\ncauses the buildup of the macroscopic population numbers of coherent localized\nsurface plasmons associated with high-intensity coherent local fields formed at\nnanoscale throughout the nanotube surface. These strong local fields can be\nused in a variety of new optoelectronic applications of carbon nanotubes,\nincluding near-field nonlinear-optical probing and sensing, optical switching,\nenhanced electromagnetic absorption, and materials nanoscale modification.",
        "positive": "Supplementary Material to the Comment on \"Photoluminescence Ring\n  Formation in Coupled Quantum Wells: Excitonic Versus Ambipolar Diffusion\": This is a supplementary material to our Comment arXiv:0909.4265 on M. Stern,\nV. Garmider, E. Segre, M. Rappaport, V. Umansky, Y. Levinson, and I.\nBar-Joseph, Phys. Rev. Lett. 101, 257402 (2008)."
    },
    {
        "anchor": "Topological edge-state contributions to high-order harmonic generation\n  in finite flakes: Edge states play a major role in the electron dynamics of topological\ninsulators as they are the only conducting part in such materials. In this\nwork, we consider the Haldane model for a 2D topological insulator, subjected\nto an intense laser field. We compare the numerically simulated high-harmonic\ngeneration (HHG) in the bulk of the Haldane model to HHG in corresponding\nfinite flakes with edge states present, and explain the differences. In\nparticular, peaks for energies below the bulk band gap appear in the spectra\nfor the finite flakes. The positions of these peaks show a strong dependence on\nthe size of the flakes, which can be explained using the dispersion relation\nfor the edge states.",
        "positive": "Spectral broadening of optical transitions at tunneling resonances in\n  InAs/GaAs coupled quantum dot pairs: We report on linewidth analysis of optical transitions in InAs/GaAs coupled\nquantum dots as a function of bias voltage, temperature, and tunnel coupling\nstrength. A significant line broadening up to 100 $\\mu$eV is observed at hole\ntunneling resonances where the coherent tunnel coupling between spatially\ndirect and indirect exciton states is maximized, corresponding to a\nphonon-assisted transition rate of 150 ns${}^{-1}$ at 20 K. With increasing\ntemperature, the linewidth shows broadening characteristic of single-phonon\ntransitions. The linewidth as a function of tunnel coupling strength tracks the\ntheoretical prediction of linewidth broadening due to phonon-assisted\ntransitions, and is maximized with an energy splitting between the two exciton\nbranches of 0.8$-$0.9 meV. This report highlights the linewidth broadening\nmechanisms and fundamental aspects of the interaction between these systems and\nthe local environment."
    },
    {
        "anchor": "Nonlocal Charge Transport Mediated by Spin Diffusion in the Spin-Hall\n  Effect Regime: A nonlocal electric response in the spin-Hall regime, resulting from spin\ndiffusion mediating charge conduction, is predicted. The spin-mediated\ntransport stands out due to its long-range character, and can give dominant\ncontribution to nonlocal resistance. The characteristic range of nonlocality,\nset by the spin diffusion length, can be large enough to allow detection of\nthis effect in materials such as GaAs despite its small magnitude. The\ndetection is facilitated by a characteristic nonmonotonic dependence of\ntransresistance on the external magnetic field, exhibiting sign changes and\ndecay.",
        "positive": "Binary switching in a symmetric potential landscape: The general methodology of binary switching requires tilting of potential\nlandscape along the desired direction of switching. The tilt generates a torque\nalong the direction of switching and the degree of tilt should be sufficient\nenough to beat thermal agitations with a tolerable error probability. However,\nwe show here that such tilt is not necessary. Considering the full\nthree-dimensional motion, we point out that the built-in dynamics can\nfacilitate switching without requiring any asymmetry in potential landscape\neven in the presence of thermal noise. With experimentally feasible parameters,\nwe theoretically demonstrate such intriguing possibility in electric\nfield-induced magnetization switching of a magnetostrictive nanomagnet."
    },
    {
        "anchor": "Spectroscopy of three strongly coupled flux qubits: We have carried out spectroscopic measurements of a system of three strongly\ncoupled four-junction flux qubits. The samples studied cover a wide range of\nparameters with the coupling energy between neighboring qubits varying between\n0.75 GHz and 6.05 GHz. The observed complicated spectra agree well with\neight-level theory. The experiments are relevant for the realization of a\ntunable coupling between qubits.",
        "positive": "Designable electron transport features in one-dimensional arrays of\n  metallic nanoparticles: Monte Carlo study of the relation between shape and\n  transport: We study the current and shot noise in a linear array of metallic\nnanoparticles taking explicitly into consideration their discrete electronic\nspectra. Phonon assisted tunneling and dissipative effects on single\nnanoparticles are incorporated as well. The capacitance matrix which determines\nthe classical Coulomb interaction within the capacitance model is calculated\nnumerically from a realistic geometry. A Monte Carlo algorithm which\nself-adapts to the size of the system allows us to simulate the single-electron\ntransport properties within a semiclassical framework. We present several\neffects that are related to the geometry and the one-electron level spacing\nlike e.g. a negative differential conductance (NDC) effect. Consequently these\neffects are designable by the choice of the size and arrangement of the\nnanoparticles."
    },
    {
        "anchor": "Tunable All Electric Spin Polarizer: We propose a new device to create a tunable all-electric spin polarizer: a\nquantum point contact (QPC) with four gates -- two in-plane side gates in\nseries. The first pair of gates, near the source, is asymmetrically biased to\ncreate spin polarization in the QPC channel. The second set of gates, near the\ndrain, is symmetrically biased and that bias is varied to maximize the amount\nof spin polarization in the channel. The range of common mode bias on the first\nset of gates over which maximum spin polarization can be achieved is much\nbroader for the four gate structure compared with the case of a single pair of\nin-plane side gates.",
        "positive": "Disorder, pseudospins, and backscattering in carbon nanotubes: We address the effects of disorder on the conducting properties of metal and\nsemiconducting carbon nanotubes. Experimentally, the mean free path is found to\nbe much larger in metallic tubes than in doped semiconducting tubes. We show\nthat this result can be understood theoretically if the disorder potential is\nlong-ranged. The effects of a pseudospin index that describes the internal\nsublattice structure of the states lead to a suppression of scattering in\nmetallic tubes, but not in semiconducting tubes. This conclusion is supported\nby tight-binding calculations."
    },
    {
        "anchor": "Field-Effect Controllable Metallic Josephson Interferometer: Gate-tunable Josephson junctions (JJs) are the backbone of superconducting\nclassical and quantum computation. Typically, these systems exploit low charge\nconcentration materials, and present technological diffculties limiting their\nscalability. Surprisingly, electric field modulation of supercurrent in\nmetallic wires and JJs has been recently demonstrated. Here, we report the\nrealization of titanium-based monolithic interferometers which allow tuning\nboth JJs independently via voltage bias applied to capacitively-coupled\nelectrodes. Our experiments demonstrate full control of the amplitude of the\nswitching current (IS) and of the superconducting phase across the single JJ in\na wide range of temperatures. Astoundingly, by gate-biasing a single junction\nthe maximum achievable total IS suppresses down to values much lower than the\ncritical current of a single JJ. A theoretical model including gate-induced\nphase fluctuations on a single junction accounts for our experimental findings.\nThis class of quantum interferometers could represent a breakthrough for\nseveral applications such as digital electronics, quantum computing, sensitive\nmagnetometry and single-photon detection.",
        "positive": "Magnetizations and de Haas-van Alphen oscillations in massive Dirac\n  fermions: We theoretically study magnetic field, temperature, and energy band-gap\ndependences of magnetizations in the Dirac fermions. We use the zeta function\nregularization to obtain analytical expressions of thermodynamic potential,\nfrom which the magnetization of graphene for strong field/low temperature and\nweak field/high temperature limits are calculated. Further, we generalize the\nresult by considering the effects of impurity on orbital susceptibility of\ngraphene. In particular, we show that in the presence of impurity, the\nsusceptibility follows a scaling law which can be approximated by the Faddeeva\nfunction. In the case of the massive Dirac fermions, we show that a large\nband-gap gives a robust magnetization with respect to temperature and impurity.\nIn the doped Dirac fermion, we discuss the dependence of the band-gap on the\nperiod and amplitude of the de Haas-van Alphen effect."
    },
    {
        "anchor": "Role of crystal structure and junction morphology on interface thermal\n  conductance: We argue that the relative thermal conductance between interfaces with\ndifferent morphologies is controlled by crystal structure through $M_{min}/M_c\n> 1$, the ratio between the {\\it minimum mode} count on either side $M_{min}$,\nand the {\\it conserving modes} $M_c$ that preserve phonon momentum transverse\nto the interface. Junctions with an added homogenous layer, \"uniform\", and\n\"abrupt\" junctions are limited to $M_c$ while junctions with interfacial\ndisorder, \"mixed\", exploit the expansion of mode spectrum to $M_{min}$. In our\nstudies with cubic crystals, the largest enhancement of conductance from\n\"abrupt\" to \"mixed\" interfaces seems to be correlated with the emergence of\nvoids in the conserving modes, where $M_c = 0$. Such voids typically arise when\nthe interlayer coupling is weakly dispersive, making the bands shift rigidly\nwith momentum. Interfacial mixing also increases alloy scattering, which\nreduces conductance in opposition with the mode spectrum expansion. Thus the\nconductance across a \"mixed' junction does not always increase relative to that\nat a \"uniform\" interface.",
        "positive": "Microwave spectroscopy of a carbon nanotube charge qubit: Carbon nanotube quantum dots allow accurate control of electron charge, spin\nand valley degrees of freedom in a material which is atomically perfect and can\nbe grown isotopically pure. These properties underlie the unique potential of\ncarbon nanotubes for quantum information processing, but developing nanotube\ncharge, spin, or spin-valley qubits requires efficient readout techniques as\nwell as understanding and extending quantum coherence in these devices. Here,\nwe report on microwave spectroscopy of a carbon nanotube charge qubit in which\nquantum information is encoded in the spatial position of an electron. We\ncombine radio-frequency reflectometry measurements of the quantum capacitance\nof the device with microwave manipulation to drive transitions between the\nqubit states. This approach simplifies charge-state readout and allows us to\noperate the device at an optimal point where the qubit is first-order\ninsensitive to charge noise. From these measurements, we are able to quantify\nthe degree of charge noise experienced by the qubit and obtain an inhomogeneous\ncharge coherence of 5 ns. We use a chopped microwave signal whose duty-cycle\nperiod is varied to measure the decay of the qubit states, yielding a charge\nrelaxation time of 48 ns."
    },
    {
        "anchor": "Conduction gap in graphene strain junctions: direction dependence: It has been shown in a recent study [Nguyen et al., Nanotechnol. \\textbf{25},\n165201 (2014)] that unstrained/strained graphene junctions are promising\ncandidates to improve the performance of graphene transistors that is usually\nhindered by the gapless nature of graphene. Although the energy bandgap of\nstrained graphene still remains zero, the shift of Dirac points in the\n\\textbf{\\emph{k}}-space due to strain-induced deformation of graphene lattice\ncan lead to the appearance of a finite conduction gap of several hundreds meV\nin strained junctions with a strain of only a few percent. However, since it\ndepends essentially on the magnitude of Dirac point shift, this conduction gap\nstrongly depends on the direction of applied strain and the transport\ndirection. In this work, a systematic study of conduction gap properties with\nrespect to these quantities is presented and the results are carefully\nanalyzed. Our study provides useful information for further investigations to\nexploit graphene strained junctions in electronic applications.",
        "positive": "Boltzmann transport and residual conductivity in bilayer graphene: A Drude-Boltzmann theory is used to calculate the transport properties of\nbilayer graphene. We find that for typical carrier densities accessible in\ngraphene experiments, the dominant scattering mechanism is overscreened Coulomb\nimpurities that behave like short-range scatterers. We anticipate that the\nconductivity $\\sigma(n)$ is linear in $n$ at high density and has a plateau at\nlow density corresponding to a residual density of $n^* = \\sqrt{n_{\\rm imp}\n{\\tilde n}}$, where ${\\tilde n}$ is a constant which we estimate using a\nself-consistent Thomas-Fermi screening approximation to be ${\\tilde n} \\approx\n0.01 ~q_{\\rm TF}^2 \\approx 140 \\times 10^{10} {\\rm cm}^{-2}$. Analytic results\nare derived for the conductivity as a function of the charged impurity density.\nWe also comment on the temperature dependence of the bilayer conductivity."
    },
    {
        "anchor": "Electronic Structure of Three-Dimensional Superlattices Subject to\n  Tilted Magnetic Fields: Full quantum-mechanical description of electrons moving in 3D structures with\nunidirectional periodic modulation subject to tilted magnetic fields requires\nan extensive numerical calculation. To understand magneto-oscillations in such\nsystems it is in many cases sufficient to use the quasi-classical approach, in\nwhich the zero-magnetic-field Fermi surface is considered as a\nmagnetic-field-independent rigid body in k-space and periods of oscillations\nare related to extremal cross-sections of the Fermi surface cut by planes\nperpendicular to the magnetic-field direction. We point out cases where the\nquasi-classical treatment fails and propose a simple tight-binding\nfully-quantum-mechanical model of the superlattice electronic structure.",
        "positive": "Nanoscale optical waveform control of strong-field photoemission: Strong-field photoemission from metal nanostructures enabled fundamental\ndiscoveries recently. Here, we deliver theoretical demonstration of the\nelectric field control of electrons in the closest nanoscale vicinity of\nplasmonic nanoparticles with the help of few-cycle laser waveforms. We analyze\nthe effect of plasmonic resonance on photoemission properties and show that it\nis only off-resonant nanoparticles that can provide electron control on a true\nsub-fs timescale."
    },
    {
        "anchor": "Conductance of quantum spin Hall edge states from first principles: the\n  critical role of magnetic impurities and inter-edge scattering: The outstanding transport properties expected at the edge of two-dimensional\ntime-reversal invariant topological insulators have proven to be challenging to\nrealize experimentally, and have so far only been demonstrated in very short\ndevices. In search for an explanation to this puzzling observation, we here\nreport a full first-principles calculation of topologically protected transport\nat the edge of novel quantum spin Hall insulators - specifically, Bismuth and\nAntimony halides - based on the non-equilibrium Green's functions formalism.\nOur calculations unravel two different scattering mechanisms that may affect\ntwo-dimensional topological insulators, namely time-reversal symmetry breaking\nat vacancy defects and inter-edge scattering mediated by multiple co-operating\nimpurities, possibly non-magnetic. We discuss their drastic consequences for\ntypical non-local transport measurements as well as strategies to mitigate\ntheir negative impact. Finally, we provide an instructive comparison of the\ntransport properties of topologically protected edge states to those of the\ntrivial edge states in MoS$_2$ ribbons. Although we focus on a few specific\ncases (in terms of materials and defect types) our results should be\nrepresentative for the general case and thus have significance beyond the\nsystems studied here.",
        "positive": "Oscillatory Size-Dependence of the Surface Plasmon Linewidth in Metallic\n  Nanoparticles: We study the linewidth of the surface plasmon resonance in the optical\nabsorption spectrum of metallic nanoparticles, when the decay into\nelectron-hole pairs is the dominant channel. Within a semiclassical approach,\nwe find that the electron-hole density-density correlation oscillates as a\nfunction of the size of the particles, leading to oscillations of the\nlinewidth. This result is confirmed numerically for alkali and noble metal\nparticles. While the linewidth can increase strongly, the oscillations persist\nwhen the particles are embedded in a matrix."
    },
    {
        "anchor": "Thermal conductivity of porous polycrystalline PbTe: PbTe is a leading thermoelectric material at intermediate temperatures,\nlargely thanks to its low lattice thermal conductivity. However, its efficiency\nis too low to compete with other forms of power generation. This efficiency can\nbe effectively enhanced by designing nanostructures capable of scattering\nphonons over a wide range of length scales to reduce the lattice thermal\nconductivity. The presence of grain boundaries can reduce the thermal\nconductivity to $\\sim 0.5$ Wm$^{-1}$K$^{-1}$ for small vacancy concentrations\nand grain sizes. However, grains anneal at finite temperature, and equilibrium\nand metastable grain size distributions determine the extent of the reduction\nin thermal conductivity. In the present work, we propose a phase-field model\ninformed by molecular dynamics simulations to study the annealing process in\nPbTe and how it is affected by the presence of grain boundaries and voids. We\nfind that the thermal conductivity of PbTe is reduced by up to 35\\% in the\nporous material at low temperatures. We observe that a phase transition at a\nfinite density of voids governs the kinetics of impeding grain growth by Zener\npinning.",
        "positive": "Exact Symmetries of Electron Interactions in the Lowest Landau Level: Considering the system of interacting electrons in the lowest Landau level we\nshow that the corresponding four-fermion Hamiltonian is invariant with respect\nto the local area-preserving transformations. Testing a certain class of\ninteraction potentials, we find that this symmetry is universal with respect to\na concrete type of potentials."
    },
    {
        "anchor": "Weak Antilocalization and Conductance Fluctuation in a\n  Sub-micrometer-sized Wire of Epitaxial Bi2Se3: In this study, we address the phase coherent transport in a\nsub-micrometer-sized Hall bar made of epitaxial Bi2Se3 thin film by probing the\nweak antilocalization (WAL) and the magnetoresistance fluctuation below 22 K.\nThe WAL effect is well described by the Hikami-Larkin-Nagaoka model, where the\ntemperature dependence of the coherence length indicates that electron\nconduction occurs quasi-one-dimensionally in the narrow Hall bar. The\ntemperature-dependent magnetoresistance fluctuation is analyzed in terms of the\nuniversal conductance fluctuation, which gives a coherence length consistent\nwith that derived from the WAL effect.",
        "positive": "Controlling stability of Bose-Einstein condensation of interacting\n  magnons in an antiferromagnet by an external magnetic field: We propose a mechanism for destabilizing or stabilizing Bose-Einstein\ncondensation (BEC) of interacting magnons in an antiferromagnet. We study how\nthe interaction between magnons affects the magnon BEC in a two-sublattice\nantiferromagnet without and with an external magnetic field. We show that in\nthe absence of the magnetic field the magnon BEC is destabilized by the\nattractive interband interaction, which is larger than the repulsive intraband\ninteraction. We also show that in the presence of the magnetic field the magnon\nBEC is stabilized only if the magnetic field is large enough to make the\nintraband interaction larger than the interband interaction. Our results\nprovide the first step for understanding the interaction effects on the magnon\nBEC in antiferromagnets and may open interaction physics of multicomponent BEC\nof magnons in magnets."
    },
    {
        "anchor": "Magnetotransport and spin dynamics in an electron gas formed at oxide\n  interfaces: We investigate the spin-dependent transport properties of a two-dimensional\nelectron gas formed at oxides' interface in the presence of a magnetic field.\nWe consider several scenarios for the oxides' properties, including oxides with\nco-linear or spiral magnetic and ferroelectric order. For spiral multiferroic\noxides, the magnetoelectric coupling and the topology of the localized magnetic\nmoments introduce additional, electric field controlled spin-orbit coupling\nthat affects the magneto-oscillation of the current. An interplay of this\nspin-orbit coupling, the exchange field, and of the applied magnetic field\nresults in a quantum, gate-controlled spin and charge Hall conductance.",
        "positive": "Giant effective Zeeman splitting in a monolayer semiconductor realized\n  by spin-selective strong light-matter coupling: Strong coupling between light and the fundamental excitations of a\ntwo-dimensional electron gas (2DEG) are of foundational importance both to pure\nphysics and to the understanding and development of future photonic\nnanotechnologies. Here we study the relationship between spin polarization of a\n2DEG in a monolayer semiconductor, MoSe$_2$, and light-matter interactions\nmodified by a zero-dimensional optical microcavity. We find robust\nspin-susceptibility of the 2DEG to simultaneously enhance and suppress\ntrion-polariton formation in opposite photon helicities. This leads to\nobservation of a giant effective valley Zeeman splitting for trion-polaritons\n(g-factor >20), exceeding the purely trionic splitting by over five times.\nGoing further, we observe robust effective optical non-linearity arising from\nthe highly non-linear behaviour of the valley-specific strong light-matter\ncoupling regime, and allowing all-optical tuning of the polaritonic Zeeman\nsplitting from 4 to >10 meV. Our experiments lay the groundwork for engineering\nquantum-Hall-like phases with true unidirectionality in monolayer\nsemiconductors, accompanied by giant effective photonic non-linearities rooted\nin many-body exciton-electron correlations."
    },
    {
        "anchor": "Higher-order bulk-boundary correspondence for topological crystalline\n  phases: We study the bulk-boundary correspondence for topological crystalline phases,\nwhere the crystalline symmetry is an order-two (anti)symmetry, unitary or\nantiunitary. We obtain a formulation of the bulk-boundary correspondence in\nterms of a subgroup sequence of the bulk classifying groups, which uniquely\ndetermines the topological classification of the boundary states. This\nformulation naturally includes higher-order topological phases as well as\ntopologically nontrivial bulk systems without topologically protected boundary\nstates. The complete bulk and boundary classification of higher-order\ntopological phases with an additional order-two symmetry or antisymmetry is\ncontained in this work.",
        "positive": "Crystallization of Levitons in the fractional quantum Hall regime: Using a periodic train of Lorentzian voltage pulses, which generates\nsoliton-like electronic excitations called Levitons, we investigate the charge\ndensity backscattered off a quantum point contact in the fractional quantum\nHall regime. We find a regular pattern of peaks and valleys, reminiscent of\nanalogous self-organization recently observed for optical solitons in\nnon-linear environments. This crystallization phenomenon is confirmed by\nadditional side dips in the Hong-Ou-Mandel noise, a feature that can be\nobserved in nowadays electron quantum optics experiments."
    },
    {
        "anchor": "Hybrid spin Hall nano-oscillators based on ferromagnetic\n  metal/ferrimagnetic insulator heterostructures: Spin-Hall nano-oscillators (SHNOs) are promising spintronic devices to\nrealize current controlled GHz frequency signals in nanoscale devices for\nneuromorphic computing and creating Ising systems. However, traditional SHNOs\n-- devices based on transition metals -- have high auto-oscillation threshold\ncurrents as well as low quality factors and output powers. Here we demonstrate\na new type of hybrid SHNO based on a permalloy (Py) ferromagnetic-metal\nnanowire and low-damping ferrimagnetic insulator, in the form of epitaxial\nlithium aluminum ferrite (LAFO) thin films. The superior characteristics of\nsuch SHNOs are associated with the excitation of larger spin-precession angles\nand volumes. We further find that the presence of the ferrimagnetic insulator\nenhances the auto-oscillation amplitude of spin-wave edge modes, consistent\nwith our micromagnetic modeling. This hybrid SHNO expands spintronic\napplications, including providing new means of coupling multiple SHNOs for\nneuromorphic computing and advancing magnonics.",
        "positive": "Fabrication of nanometer-spaced electrodes using gold nanoparticles: A simple and highly reproducible technique is demonstrated for the\nfabrication of metallic electrodes with nanometer separation. Commercially\navailable bare gold colloidal nanoparticles are first trapped between\nprefabricated large-separation electrodes to form a low-resistance bridge by an\nac electric field. A large dc voltage is then applied to break the bridge via\nelectromigration at room temperature, which consistently produces gaps in the\nsub-10 nm range. The technique is readily applied to prefabricated electrodes\nwith separation up to 1 micron, which can be defined using optical lithography.\nThe simple fabrication scheme will facilitate electronic transport studies of\nindividual nanostructures made by chemical synthesis. As an example,\nmeasurement of a thiol-coated gold nanoparticle showing a clear Coulomb\nstaircase is presented."
    },
    {
        "anchor": "The generator coordinate method in time-dependent density-functional\n  theory: memory made simple: The generator coordinate (GC) method is a variational approach to the quantum\nmany-body problem in which interacting many-body wave functions are constructed\nas superpositions of (generally nonorthogonal) eigenstates of auxiliary\nHamiltonians containing a deformation parameter. This paper presents a\ntime-dependent extension of the GC method as a new approach to improve existing\napproximations of the exchange-correlation (XC) potential in time-dependent\ndensity-functional theory (TDDFT). The time-dependent GC method is shown to be\na conceptually and computationally simple tool to build memory effects into any\nexisting adiabatic XC potential. As an illustration, the method is applied to\ndriven parametric oscillations of two interacting electrons in a harmonic\npotential (Hooke's atom). It is demonstrated that a proper choice of\ntime-dependent generator coordinates in conjunction with the adiabatic\nlocal-density approximation reproduces the exact linear and nonlinear\ntwo-electron dynamics quite accurately, including features associated with\ndouble excitations that cannot be captured by TDDFT in the adiabatic\napproximation.",
        "positive": "Exclusion Statistics of Composite Fermions: The exclusion statistics parameter of composite fermions is determined as an\nodd number ($\\alpha=3$, 5, ...). The statistics of composite fermion\nexcitations at $\\nu= \\frac{n}{2pn+1}$ is rederived as\n$\\alpha_{qe}^{CF}=1+\\frac{2p}{2pn+1}$, $\\alpha_{qh}^{CF}=1-\\frac{2p}{2pn+1}$.\nThe duality $\\frac{1}{\\alpha_{qe}(n,2p)}=\\alpha_{qh}(n+1,2p)$ is found. The\ndistribution function for $\\alpha=3$ is obtained."
    },
    {
        "anchor": "Towards Realistic Time-Resolved Simulations of Quantum Devices: We report on our recent efforts to perform realistic simulations of large\nquantum devices in the time domain. In contrast to d.c. transport where the\ncalculations are explicitly performed at the Fermi level, the presence of\ntime-dependent terms in the Hamiltonian makes the system inelastic so that it\nis necessary to explicitly enforce the Pauli principle in the simulations. We\nillustrate our approach with calculations for a flying qubit interferometer, a\nnanoelectronic device that is currently under experimental investigation. Our\ncalculations illustrate the fact that many degrees of freedom (16,700\ntight-binding sites in the scattering region) and long simulation times (80,000\ntimes the inverse Bandwidth of the tight-binding model) can be easily achieved\non a local computer.",
        "positive": "Characterization of aluminum oxide tunnel barriers by combining\n  transport measurements and transmission electron microscope imaging: We present two approaches for studying the uniformity of a tunnel barrier.\nThe first approach is based on measuring single-electron and two-electron\ntunneling in a hybrid single-electron transistor. Our measurements indicate\nthat the effective area of a conduction channel is about one order of magnitude\nlarger than predicted by theoretical calculations. With the second method,\ntransmission electron microscopy, we demonstrate that variations in the barrier\nthickness are a plausible explanation for the larger effective area and an\nenhancement of higher order tunneling processes."
    },
    {
        "anchor": "Comparison between a quantum kinetic theory of spin transfer dynamics in\n  Mn doped bulk semiconductors and its Markov limit for non-zero Mn\n  magnetization: We investigate the transfer between carrier and Mn spins due to the\ns-d-exchange interaction in a Mn doped bulk semiconductor within a microscopic\nquantum kinetic theory. We demonstrate that the spin transfer dynamics is\nqualitatively different for components of the carrier spin parallel and\nperpendicular to the Mn magnetization. From our quantum kinetic equations we\nhave worked out the corresponding Markov limit which is equivalent to rate\nequations based on Fermi's golden rule. The resulting equations resemble the\nwidely used Landau-Lifshitz-Gilbert-equations, but also describe genuine spin\ntransfer due to quantum corrections. Although it is known that the Markovian\nrate description works well for bulk systems when the initial Mn magnetization\nis zero, we find large qualitative deviations from the full quantum kinetic\ntheory for finite initial Mn magnetizations. These deviations mainly reflect\ncorrections of higher than leading order in the interaction which are not\naccounted for in golden rule-type rates.",
        "positive": "Quantum coherence in a ferromagnetic metal: time-dependent conductance\n  fluctuations: Quantum coherence of electrons in ferromagnetic metals is difficult to assess\nexperimentally. We report the first measurements of time-dependent universal\nconductance fluctuations in ferromagnetic metal (Ni$_{0.8}$Fe$_{0.2}$)\nnanostructures as a function of temperature and magnetic field strength and\norientation. We find that the cooperon contribution to this quantum correction\nis suppressed, and that domain wall motion can be a source of\ncoherence-enhanced conductance fluctuations. The fluctuations are more strongly\ntemperature dependent than those in normal metals, hinting that an unusual\ndephasing mechanism may be at work."
    },
    {
        "anchor": "Tunnel Magnetoresistance with Atomically Thin Two-Dimensional Hexagonal\n  Boron Nitride Barriers: The two-dimensional atomically thin insulator hexagonal boron nitride (h-BN)\nconstitutes a new paradigm in tunnel based devices. A large band gap along with\nits atomically flat nature without dangling bonds or interface trap states\nmakes it an ideal candidate for tunnel spin transport in spintronic devices.\nHere, we demonstrate the tunneling of spin-polarized electrons through large\narea monolayer h-BN prepared by chemical vapor deposition in magnetic tunnel\njunctions. In ferromagnet/h-BN/ferromagnet heterostructures fabricated over a\nchip scale, we show tunnel magneto resistance at room temperature. Measurements\nat different bias voltages and on multiple devices with different ferromagnetic\nelectrodes establish the spin polarized tunneling using h-BN barriers. These\nresults open the way for integration of 2D monolayer insulating barriers in\nactive spintronic devices and circuits operating at ambient temperature, and\nfor further exploration of their properties and prospects.",
        "positive": "Thermally Assisted Current-Driven Bistable Precessional Regimes in\n  Asymmetric Spin Valves: Spin-transfer torque in asymmetric spin valves can destabilize both parallel\nand antiparallel configurations and can lead to precessional modes also in the\nabsence of an external magnetic field. We find a bistable precessional regime\nin such systems and show that thermal fluctuations can excite transitions\n(telegraph noise) between the corresponding oscillatory regimes that are well\nseparated by irreversible paths at low temperatures. Because of the thermally\ninduced transitions, the frequency of the resulting current-driven oscillations\nis different from that obtained at very low temperatures. We also show that the\npower spectrum in the bistable region is dominated by the out-of-plane\noscillatory mode."
    },
    {
        "anchor": "Anderson localization at the boundary of a two-dimensional topological\n  superconductor: A one-dimensional boundary of a two-dimensional topological superconductor\ncan host a number of topologically protected chiral modes. Combining two\ntopological superconductors with different topological indices, it is possible\nto achieve a situation when only a given number of channels ($m$) are\ntopologically protected, while others are not and therefore are subject to\nAnderson localization in the presence of disorder. We study transport\nproperties of such quasi-one-dimensional quantum wires with broken\ntime-reversal and spin-rotational symmetries (class D) and calculate the\naverage conductance, its variance and the third cumulant, as well as the\naverage shot noise power. The results are obtained for arbitrary wire length,\ntracing a crossover from the diffusive Drude regime to the regime of strong\nlocalization where only $m$ protected channels conduct. Our approach is based\non the non-perturbative treatment of the non-linear supersymmetric sigma model\nof symmetry class D with two replicas developed in our recent publication [D.\nS. Antonenko et al., Phys. Rev. B 102, 195152 (2020)]. The presence of\ntopologically protected modes results in the appearance of a topological\nWess-Zumino-Witten term in the sigma-model action, which leads to an additional\nsubsidiary series of eigenstates of the transfer-matrix Hamiltonian. The\ndeveloped formalism can be applied to study the interplay of Anderson\nlocalization and topological protection in quantum wires of other symmetry\nclasses.",
        "positive": "Electrical observation of a tunable band gap in bilayer graphene\n  nanoribbons at room temperature: We investigate the transport properties of double-gated bilayer graphene\nnanoribbons at room temperature. The devices were fabricated using conventional\nCMOS-compatible processes. By analyzing the dependence of the resistance at the\ncharge neutrality point as a function of the electric field applied\nperpendicular to the graphene surface, we show that a band gap in the density\nof states opens, reaching an effective value of ~sim50 meV. This demonstrates\nthe potential of bilayer graphene as FET channel material in a conventional\nCMOS environment."
    },
    {
        "anchor": "Signatures of electron-magnon interaction in charge and spin currents in\n  magnetic tunnel junctions: A nonequilibrium many-body perturbation theory\n  approach: We develop a numerically exact scheme for resumming certain classes of\nFeynman diagrams in the self-consistent perturbation expansion for the electron\nand magnon self-energies in the nonequilibrium Green function formalism applied\nto a coupled electron-magnon (\\mbox{e-m}) system which is driven out of\nequilibrium by the applied finite bias voltage. Our scheme operates with the\nelectronic and magnonic GFs and the corresponding self-energies viewed as\nmatrices in the Keldysh space, rather than conventionally extracting their\nretarded and lesser components. This is employed to understand the effect of\ninelastic \\mbox{e-m} scattering on charge and spin current vs. bias voltage\n$V_b$ in F/I/F magnetic tunnel junctions (MTJs), which are modeled on a\none-dimensional (1D) tight-binding lattice for the electronic subsystem and 1D\nHeisenberg model for the magnonic subsystem. For this purpose, we evaluate Fock\ndiagram for the electronic self-energy and the electron-hole polarization\nbubble diagram for the magnonic self-energy. The respective electronic and\nmagnonic GF lines within these diagrams are the fully interacting ones, thereby\nrequiring to solve the ensuing coupled system of nonlinear integral equations\nself-consistently. Despite using the 1D model and treating \\mbox{e-m}\ninteraction in many-body fashion only within a small active region consisting\nof few lattice sites around the F/I interface, our analysis captures essential\nfeatures of the so-called zero-bias anomaly observed in both MgO- and\nAlO$_x$-based realistic 3D MTJs where the second derivative $d^2 I/dV_b^2$\n(i.e., inelastic electron tunneling spectrum) of charge current exhibits sharp\npeaks of opposite sign on either side of the zero bias voltage.",
        "positive": "Exchange-interaction of two spin qubits mediated by a superconductor: Entangling two quantum bits by letting them interact is the crucial\nrequirements for building a quantum processor. For qubits based on the spin of\nthe electron, these two-qubit gates are typically performed by exchange\ninteraction of the electrons captured in two nearby quantum dots. Since the\nexchange interaction relies on tunneling of the electrons, the range of\ninteraction for conventional approaches is severely limited as the tunneling\namplitude decays exponentially with the length of the tunneling barrier. Here,\nwe present a novel approach to couple two spin qubits via a superconducting\ncoupler. In essence, the superconducting coupler provides a tunneling barrier\nfor the electrons which can be tuned with exquisite precision. We show that as\na result exchange couplings over a distance of several microns become\nrealistic, thus enabling flexible designs of multi-qubit systems."
    },
    {
        "anchor": "Spin Hall Effect: This is a brief review of the phenomenology of the spin Hall effect and\nrelated phenomena.",
        "positive": "Collective fluorescence and decoherence of a few nearly identical\n  quantum dots: We study the collective interaction of excitons in closely spaced artificial\nmolecules and arrays of nearly identical quantum dots with the electromagnetic\nmodes. We discuss how collective fluorescence builds up in the presence of a\nsmall mismatch of the transition energy. We show that a superradiant state of a\nsingle exciton in a molecule of two dots with realistic energy mismatch\nundergoes a two-rate decay. We analyze also the stability of subdecoherent\nstates for non-identical systems."
    },
    {
        "anchor": "The photonic trumpet: An efficient, broadband interface between a\n  solid-state quantum emitter and a Gaussian beam: We introduce the photonic trumpet, a dielectric structure which ensures a\nnearly perfect coupling between an embedded quantum light source and a Gaussian\nfree-space beam. A photonic trumpet exploits both the broadband spontaneous\nemission control provided by a single-mode photonic wire and the adiabatic\nexpansion of this mode within a conical taper. Numerical simulations highlight\nthe outstanding performance and robustness of this concept. As a first\napplication in the field of quantum optics, we report the realisation of an\nultra-bright single-photon source. The device, a GaAs photonic trumpet\ncontaining few InAs quantum dots, demonstrates a first-lens external efficiency\nof $0.75 \\pm 0.1$.",
        "positive": "Berry Curvature Spectroscopy from Bloch Oscillations: Artificial crystals such as moir\\'e superlattices can have a real-space\nperiodicity much larger than the underlying atomic scale. This facilitates the\npresence of Bloch oscillations in the presence of a static electric field. We\ndemonstrate that the optical response of such a system, when dressed with a\nstatic field, becomes resonant at the frequencies of Bloch oscillations, which\nare in the terahertz regime when the lattice constant is of the order of 10 nm.\nIn particular, we show within a semiclassical band-projected theory that\nresonances in the dressed Hall conductivity are proportional to the lattice\nFourier components of the Berry curvature. We illustrate our results with a\nlow-energy model on an effective honeycomb lattice."
    },
    {
        "anchor": "Microwave response of a two-dimensional electron stripe: Electromagnetic response of a finite-width two-dimensional electron stripe is\ntheoretically studied. It is shown that retardation and radiative effects\nsubstantially modify the absorption spectrum of the system at microwave\nfrequencies, leading to a non-trivial zigzag behavior of the\nmagnetoplasmon-polariton modes in magnetic fields, similar to that recently\nobserved by Kukushkin et al. [Phys. Rev. Lett. {\\bf 90}, 156801 (2003)].",
        "positive": "Weiss oscillations in the electronic structure of modulated graphene: We present a theoretical study of the electronic structure of modulated\ngraphene in the presence of a perpendicular magnetic field. The density of\nstates and the bandwidth for the Dirac electrons in this system are determined.\nThe appearance of unusual Weiss oscillations in the bandwidth and density of\nstates is the main focus of this work."
    },
    {
        "anchor": "Interaction Effects on the Conductance in One-Dimensional Systems --\n  Short-Range Interaction --: We investigate the effect of electron-electron interactions on the\nconductance of quasi one-dimensional systems without potential scattering. For\na finite temperature or system length, the short-range interaction is not\nrenormalized to 0, and it gives rise to a finite correction to the conductance\nif we calculate it using Kubo formula. We show that this correction can be\nabsorbed into the renormalization of the chemical potential and that the\nproperly defined conductance to be observed in the experiments is equal to that\nof non-interacting electrons.",
        "positive": "Electronic transport in a two-dimensional superlattice engineered via\n  self-assembled nanostructures: Nanoscience offers a unique opportunity to design modern materials from the\nbottom up, via low-cost, solution processed assembly of nanoscale building\nblocks. These systems promise electronic band structure engineering using not\nonly the nanoscale structural modulation, but also the mesoscale spatial\npatterning, although experimental realization of the latter has been\nchallenging. Here we design and fabricate a new type of artificial solid by\nstacking graphene on a self-assembled, nearly periodic array of nanospheres,\nand experimentally observe superlattice miniband effects. We find conductance\ndips at commensurate fillings of charge carriers per superlattice unit cell,\nwhich are key features of minibands that are induced by the quasi-periodic\ndeformation of the graphene lattice. These dips become stronger when the\nlattice strain is larger. Using a tight-binding model, we simulate the effect\nof lattice deformation as a parameter affecting the inter-atomic hopping\nintegral, and confirm the superlattice transport behavior. This 2D\nmaterial-nanoparticle heterostructure enables facile band structure engineering\nvia self-assembly, promising for large area electronics and optoelectronics\napplications."
    },
    {
        "anchor": "Vibrations of weakly-coupled nanoparticles: The vibrations of a coupled pair of isotropic silver spheres are investigated\nand compared with the vibrations of the single isolated spheres. Situations of\nboth strong coupling and also weak coupling are investigated using continuum\nelasticity and perturbation theory. The numerical calculation of the eigenmodes\nof such dimers is augmented with a symmetry analysis. This checks the\nconvergence and applicability of the numerical method and shows how the\neigenmodes of the dimer are constructed from those of the isolated spheres. The\nfrequencies of the lowest frequency vibrations of such dimers are shown to be\nvery sensitive to the strength of the coupling between the spheres. Some of\nthese modes can be detected by inelastic light scattering and time-resolved\noptical measurements which provides a convenient way to study the nature of the\nmechanical coupling in dimers of micro and nanoparticles.",
        "positive": "Regular Rather than Chaotic Origin of the Resonant Transport in\n  Superlattices: We address the enhancement of electron drift in semiconductor superlattices\nof nanometre scale that occurs in combined electric and tilted magnetic fields\nif Bloch oscillations become resonant with cyclotron rotation in the transverse\nplane. We uncover the true dynamical mechanism of the phenomenon: the electron\ndynamics at relevant time-scales is regular or almost regular, contrary to the\nwidespread belief that the enhancement arises through chaotic diffusion between\ncollisions. The theory provides an accurate description of earlier numerical\nsimulations, predicts new remarkable features verified by simulations, and\nsuggests new ways of controlling resonant transport."
    },
    {
        "anchor": "Paramagnetic reentrant effect in high purity mesoscopic AgNb proximity\n  structures: We discuss the magnetic response of clean Ag coated Nb proximity cylinders in\nthe temperature range 150 \\mu K < T < 9 K. In the mesoscopic temperature\nregime, the normal metal-superconductor system shows the yet unexplained\nparamagnetic reentrant effect, discovered some years ago [P. Visani, A. C.\nMota, and A. Pollini, Phys. Rev. Lett. 65, 1514 (1990)], superimposing on full\nMeissner screening. The logarithmic slope of the reentrant paramagnetic\nsusceptibility chi_para(T) \\propto \\exp(-L/\\xi_N) is limited by the condition\n\\xi_N=n L, with \\xi_N=\\hbar v_F/2 \\pi k_B T, the thermal coherence length and\nn=1,2,4. In wires with perimeters L=72 \\mu m and L=130 \\mu m, we observe\ninteger multiples n=1,2,4. At the lowest temperatures, \\chi_para compensates\nthe diamagnetic susceptibility of the \\textit{whole} AgNb structure.",
        "positive": "Short circuit current enhancement in GaAs/AlGaAs MQW solar cells: The GaAs/AlGaAs quantum well solar cell (QWSC) shows promise as a novel\napproach to higher efficiency solar cells but suffers from a poor short circuit\ncurrent Jsc. We report on efforts to reduce this problem with the use of\ncompositional grading and back surface mirroring. We present experimental\nquantum efficiency (QE) data on a range of compositionally graded QWSCs and\ndevices in which the back surface of the cell is coated with a mirror,\nincreasing the optical thickness of the quantum well layer in the long\nwavelength range. The experimental QE spectra are reproduced by a model which\ndeals with arbitrary compositional profiles and optical cavities formed in the\nmirrored cells. The model is used to design an optimised QWSC, and projected\nJsc values given. Applications including II-VI and tandem solar cells are\nconsidered."
    },
    {
        "anchor": "Triple nodal points characterized by their nodal-line structure in all\n  magnetic space groups: We analyze triply degenerate nodal points [or triple points (TPs) for short]\nin energy bands of crystalline solids. Specifically, we focus on spinless band\nstructures, i.e., when spin-orbit coupling is negligible, and consider TPs\nformed along high-symmetry lines in the momentum space by a crossing of three\nbands transforming according to a 1D and a 2D irreducible corepresentation\n(ICR) of the little co-group. The result is a complete classification of such\nTPs in all magnetic space groups, including the non-symmorphic ones, according\nto several characteristics of the nodal-line structure at and near the TP. We\nshow that the classification of the presently studied TPs is exhausted by 13\nmagnetic point groups (MPGs) that can arise as the little co-group of a\nhigh-symmetry line and which support both 1D and 2D spinless ICRs. For 10 of\nthe identified MPGs, the TP characteristics are uniquely determined without\nfurther information; in contrast, for the 3 MPGs containing sixfold rotational\nsymmetry, two types of TPs are possible, depending on the choice of the\ncrossing ICRs. The classification result for each of the 13 MPGs is illustrated\nwith first-principles calculations of a concrete material candidate.",
        "positive": "Electronic transport in an array of quasi-particles in the nu=5/2\n  non-abelian quantum Hall state: The Moore-Read Pfaffian $\\nu=5/2$ quantum Hall state is a p-wave\nsuper-conductor of composite fermions. Small deviations from $\\nu=5/2$ result\nin the formation of an array of vortices within this super-conductor, each\nsupporting a Majorana zero mode near its core. Here we consider how tunneling\nbetween these cores is reflected in the electronic response to an electric\nfield of non-zero wave vector $\\bf q$ and frequency $\\omega$. We find a\nmechanism for dissipative transport at frequencies below the $\\nu=5/2$ gap, and\ncalculate the ${\\bf q},\\omega$ dependence of the dissipative conductivity. The\ncontributions we find depend exponentially on $|\\nu-5/2|^{-1/2}$."
    },
    {
        "anchor": "Micromagnetic simulations of persistent oscillatory modes excited by\n  spin-polarized current in nanoscale exchange-biased spin valves: We perform 3D micromagnetic simulations of current-driven magnetization\ndynamics in nanoscale exchange biased spin-valves that take account of (i) back\naction of spin-transfer torque on the pinned layer, (ii) non-linear damping and\n(iii) random thermal torques. Our simulations demonstrate that all these\nfactors significantly impact the current-driven dynamics and lead to a better\nagreement between theoretical predictions and experimental results. In\nparticular, we observe that, at a non-zero temperature and a sub-critical\ncurrent, the magnetization dynamics exhibits nonstationary behaviour in which\ntwo independent persistent oscillatory modes are excited which compete for the\nangular momentum supplied by spin-polarized current. Our results show that this\nmulti-mode behaviour can be induced by combined action of thermal and spin\ntransfer torques.",
        "positive": "Theory of charge and spin pumping in atomic-scale spiral magnets: An Archimedean screw is a classical pump that exploits the equivalence of\nrotation and translation in helices. Similarly, a spin spiral texture can pump\ncharge and spin by rotating at a frequency $\\omega$. In the present paper, we\nstudy these pumping phenomena within a microscopic quantum model by both\nperturbation theory and numerical simulations. Inside the spiral region, the\nspin polarization and charge current are linear in $\\omega$ whereas the spin\ncurrent is $\\omega^2$ for small $\\omega$. We find that the charge current is\nrelated to the mixed momentum-phason Berry phase, which can be viewed as a\nnovel approximate realization of a Thouless pump. It is nearly quantized in\nspirals with short pitch $\\lambda$ but decays with $\\lambda^{-1}$ for longer\npitches, unlike true Thouless pumps or Archimedian screws. Moreover, we study\nthe onset of non-adiabaticity (large $\\omega$), the impact of attached\nnon-magnetic or magnetic contacts, and the real-time evolution of the transport\nobservables. Finally, we analyze the effects of disorders which, surprisingly,\nmight enhance the spin current but suppress the charge current."
    },
    {
        "anchor": "Magneto-optical effects in the Landau level manifold of 2D lattices with\n  spin-orbit interaction: Silicene is a competitive and promising 2D material, possessing interesting\ntopological, electronic and optical properties. The presence of strong spin\norbit interaction in silicene and its analogues, germanene and tinene, leads to\nthe opening of a gap in the energy spectrum and spin-splitting of the bands in\neach valley. We develop a general method to determine the magneto-optic\nresponse of silicene, when a Gaussian beam is incident on silicene grown on a\ndielectric substrate in the presence of a static magnetic field. We use a\nsemiclassical treatment of silicene monolayer to describe the Faraday rotation\n(FR) and Magneto-optical Kerr effect (MOKE) using a general model for beam\npropagation. The response can be modulated both electrically and magnetically.\nWe derive analytic expressions for valley and spin polarized FR and MOKE for\narbitrary polarization of incident light in the terahertz regime. We\ndemonstrate that large FR and MOKE can be achieved by tuning the electric\nfield, magnetic fields and chemical potential in these fascinating 2D\nmaterials. Implications for novel valleytronic experiments are also discussed.",
        "positive": "Nonequilibrium spintronic transport through Kondo impurities: In this work we analyze the nonequilibrium transport through a quantum\nimpurity (quantum dot or molecule) attached to ferromagnetic leads by using a\nhybrid numerical renormalization group-time-dependent density matrix\nrenormalization group thermofield quench approach.For this, we study the bias\ndependence of the differential conductance through the system, which shows a\nfinite zero-bias peak, characteristic of the Kondo resonance and reminiscent of\nthe equilibrium local density of states. In the non-equilibrium settings, the\nresonance in the differential conductance is also found to decrease with\nincreasing the lead spin polarization. The latter induces an effective exchange\nfield that lifts the spin degeneracy of the dot level. Therefore as we\ndemonstrate, the Kondo resonance can be restored by counteracting the exchange\nfield with a finite external magnetic field applied to the system. Finally, we\ninvestigate the influence of temperature on the nonequilibrium conductance,\nfocusing on the split Kondo resonance. Our work thus provides an accurate\nquantitative description of the spin-resolved transport properties relevant for\nquantum dots and molecules embedded in magnetic tunnel junctions."
    },
    {
        "anchor": "Valley and spin accumulation in ballistic and hydrodynamic channels: A theory of the valley and spin Hall effects and resulting accumulation of\nthe valley and spin polarization is developed for ultraclean channels made of\ntwo-dimensional semiconductors where the electron mean free path due to the\nresidual disorder or phonons exceeds the channel width. Both ballistic and\nhydrodynamic regimes of the electron transport are studied. The polarization\naccumulation is determined by interplay of the anomalous velocity, side-jump\nand skew scattering effects. In the hydrodynamic regime, where the\nelectron-electron scattering is dominant, the valley and spin current\ngeneration and dissipation by the electron-electron collisions are taken into\naccount. The accumulated polarization magnitude and its spatial distribution\ndepend strongly on the transport regime. The polarization is much larger in the\nhydrodynamic regime as compared to the ballistic one. Significant valley and\nspin polarization arises in the immediate vicinity of the channel edges due to\nthe side-jump and skew scattering mechanisms.",
        "positive": "Goos-H\u00e4nchen effect in light transmission through biperiodic\n  photonic-magnonic crystals: We present a theoretical investigation of the Goos-H\\\"anchen effect, i.e.,\nthe lateral shift of the light beam transmitted through one-dimensional\nbiperiodic multilayered photonic systems consisting of equidistantmagnetic\nlayers separated by finite size dielectric photonic crystals. We show that the\nincrease of the number of periods in the photonic-magnonic structure leads to\nincrease of the Goos-H\\\"anchen shift in the vicinity of the frequencies of\ndefect modes located inside the photonic band gaps. Presence of the linear\nmagnetoelectric coupling in the magnetic layers can result in a vanishing of\nthe positive maxima of the cross-polarized contribution to the Goos-H\\\"anchen\nshift."
    },
    {
        "anchor": "Topological insulators and superconductors: ten-fold way and dimensional\n  hierarchy: It has recently been shown that in every spatial dimension there exist\nprecisely five distinct classes of topological insulators or superconductors.\nWithin a given class, the different topological sectors can be distinguished,\ndepending on the case, by a Z or a Z_2 topological invariant. This is an\nexhaustive classification. Here we construct representatives of topological\ninsulators and superconductors for all five classes and in arbitrary spatial\ndimension d, in terms of Dirac Hamiltonians. Using these representatives we\ndemonstrate how topological insulators (superconductors) in different\ndimensions and different classes can be related via dimensional reduction by\ncompactifying one or more spatial dimensions (in Kaluza-Klein-like fashion).\nFor Z-topological insulators (superconductors) this proceeds by descending by\none dimension at a time into a different class. The Z_2-topological insulators\n(superconductors), on the other hand, are shown to be lower-dimensional\ndescendants of parent Z-topological insulators in the same class, from which\nthey inherit their topological properties. The 8-fold periodicity in dimension\nd that exists for topological insulators (superconductors) with Hamiltonians\nsatisfying at least one reality condition (arising from time-reversal or\ncharge-conjugation/particle-hole symmetries) is a reflection of the 8-fold\nperiodicity of the spinor representations of the orthogonal groups SO(N) (a\nform of Bott periodicity). We derive a relation between the topological\ninvariant that characterizes topological insulators/superconductors with chiral\nsymmetry and the Chern-Simons invariant: it relates the invariant to the\nelectric polarization (d=1), or to the magnetoelectric polarizability (d=3).\nFinally, we discuss topological field theories describing the space time theory\nof linear responses, and study how the presence of inversion symmetry modifies\nthe classification.",
        "positive": "Large insulating nitride islands on Cu3Au as a template for atomic spin\n  structures: We present controlled growth of c(2$\\times$2)N islands on the (100) surface\nof Cu$_3$Au, which can be used as an insulating surface template for\nmanipulation of magnetic adatoms. Compared to the commonly used\nCu(100)/c(2$\\times$2)N surface, where island sizes do not exceed several\nnanometers due to strain limitation, the current system provides better lattice\nmatching between metal and adsorption layer, allowing larger unstrained islands\nto be formed. We show that we can achieve island sizes ranging from tens to\nhundreds of nanometers, increasing the potential building area by a factor\n10$^3$. Initial manipulation attempts show no observable difference in adatom\nbehaviour, either in manipulation or spectroscopy."
    },
    {
        "anchor": "Transport properties of 2D-electron gas in a n-InGaAs/GaAs DQW in a\n  vicinity of low magnetic-field-induced Hall insulator--quantum Hall liquid\n  transition: The resistivity (R) of low mobility dilute 2D-electron gas in a n-InGaAs/GaAs\ndouble quantum well (DQW) exhibits the monotonic 'insulating-like' temperature\ndependence (dR/dT < 0) at T = 1.8 -- 70K in zero magnetic field. This\ntemperature interval corresponds to a ballistic regime (kTtau/hbar > 0.1 --\n3.5) for our samples, and the electron density is on a 'insulating' side of the\nso-called B = 0 2D metal--insulator transition. We show that the observed\nlocalization and Landau quantization is due to the Sigma_xy(T)anomalous\nT-dependence.",
        "positive": "Nonlinear Chiral Transport in Dirac Semimetals: We study the current of chiral charge density in a Dirac semimetal with two\nDirac points in momentum space, subjected to an externally applied time\ndependent electric field and in the presence of a magnetic field. Based on the\nkinetic equation approach, we find contributions to the chiral charge current,\nthat are proportional to the second power of the electric field and to the\nfirst and second powers of the magnetic field, describing the interplay of the\nchiral anomaly and the drift motion of electrons moving under the action of\nelectric and magnetic fields."
    },
    {
        "anchor": "On the anisotropy barrier reduction in fast relaxing Mn12\n  single-molecule magnets: A novel angle-swept high-frequency EPR (HFEPR) technique is described that\nenables in-situ alignment of single-crystal samples containing low-symmetry\nmagnetic species such as single-molecule magnets (SMMs). This cavity-based\nmethod involves recording spectra at fixed frequency and field, while sweeping\nthe field orientation. The method is applied to the study of a low-symmetry\nJahn-Teller variant of the spin S = 10 Mn12 SMMs (e.g. Mn12-acetate). The\nlow-symmetry complex is also an SMM, but with a significantly reduced barrier\nto magnetization reversal (Ueff ~ 43 K) and, hence, faster relaxation at low\ntemperature in comparison with the high-symmetry species. Mn12 complexes that\ncrystallize in lower symmetry structures exhibit a tendency for one or more of\nthe Mn(III) Jahn-Teller axes to be abnormally oriented, which is believed to be\nthe cause of the faster relaxation. An extensive HFEPR study of\n[Mn12O12(O2CCH2But)16(H2O)4].CH2Cl2.MeNO2 is presented in order to examine the\ninfluence of the abnormally oriented Jahn-Teller axis on the effective barrier.\nThe reduction in the axial anisotropy, D, is found to be insufficient to\naccount for the nearly 40% reduction in Ueff. However, the reduced symmetry of\nthe Mn12 core gives rise to a very significant 2nd order transverse anisotropy,\nE ~ D/6. This, in turn, causes a significant mixing of spin projection states\nwell below the top of the classical barrier. Thus, magnetic quantum tunneling\nis the dominant factor contributing to the barrier reduction in fast relaxing\nMn12 SMMs.",
        "positive": "Quantum \"contact\" friction: the contribution of kinetic friction\n  coefficient from thermal fluctuations: A thermal model of kinetic friction is assigned to a classical loaded\nparticle moving on a fluctuating smooth surface. A sinusoidal wave resembles\nsurface fluctuations with a relaxation time. The Hamiltonian is approximated to\nthe mean energy of the wave describing a system of Harmonic oscillators. The\nquantization of amplitudes yields in terms of annihilation and creation\noperators multiplied by a quantum phase. Further, we consider acoustic\ndispersion relation and evaluate the friction coefficient from the force\nautocorrelation function. While the sliding particle remains classical\ndescribing a nano-particle or a tip with negligible quantum effects like\ntunneling or delocalization in the wave function, the quantized model of the\nsurface fluctuations results in the temperature dependence of the kinetic\nfriction coefficient. It follows an asymptotic value for higher temperatures\nand supperslipperiness at low temperatures."
    },
    {
        "anchor": "Conforming nanoparticle sheets to surfaces with Gaussian curvature: Nanoparticle monolayer sheets are ultrathin inorganic-organic hybrid\nmaterials that combine highly controllable optical and electrical properties\nwith mechanical flexibility and remarkable strength. Like other thin sheets,\ntheir low bending rigidity allows them to easily roll into or conform to\ncylindrical geometries. Nanoparticle monolayers not only can bend, but also\ncope with strain through local particle rearrangement and plastic deformation.\nThis means that, unlike thin sheets such as paper or graphene, nanoparticle\nsheets can much more easily conform to surfaces with complex topography\ncharacterized by non-zero Gaussian curvature, like spherical caps or saddles.\nHere, we investigate the limits of nanoparticle monolayers' ability to conform\nto substrates with Gaussian curvature by stamping nanoparticle sheets onto\nlattices of larger polystyrene spheres. Tuning the local Gaussian curvature by\nincreasing the size of the substrate spheres, we find that the stamped sheet\nmorphology evolves through three characteristic stages: from full substrate\ncoverage, where the sheet extends over the interstices in the lattice, to\ncoverage in the form of caps that conform tightly to the top portion of each\nsphere and fracture at larger polar angles, to caps that exhibit radial folds.\nThrough analysis of the nanoparticle positions, obtained from scanning electron\nmicrographs, we extract the local strain tensor and track the onset of\nstrain-induced dislocations in the particle arrangement. By considering the\ninterplay of energies for elastic and plastic deformations and adhesion, we\nconstruct arguments that capture the observed changes in sheet morphology as\nGaussian curvature is tuned over two orders of magnitude.",
        "positive": "Hybrid moir\u00e9 excitons and trions in twisted MoTe$_2$-MoSe$_2$\n  heterobilayers: We report experimental and theoretical studies of MoTe$_2$-MoSe$_2$\nheterobilayers with rigid moir\\'e superlattices controlled by the twist angle.\nUsing an effective continuum model that combines resonant interlayer electron\ntunneling with stacking-dependent moir\\'e potentials, we identify the nature of\nmoir\\'e excitons and the dependence of their energies, oscillator strengths and\nLand\\'e $g$-factors on the twist angle. Within the same framework, we interpret\ndistinct signatures of bound complexes among electrons and moir\\'e excitons in\nnearly collinear heterostacks. Our work provides fundamental understanding of\nhybrid moir\\'e excitons and trions in MoTe$_2$-MoSe$_2$ heterobilayers, and\nestablishes the material system as a prime candidate for optical studies of\ncorrelated phenomena in moir\\'e lattices."
    },
    {
        "anchor": "Energy dissipation in DC-field driven electron lattice coupled to\n  fermion baths: Electron transport in electric-field-driven tight-binding lattice coupled to\nfermion baths is comprehensively studied. We reformulate the problem by using\nthe scattering state method within the Coulomb gauge. Calculations show that\nthe formulation justifies direct access to the steady-state bypassing the\ntime-transient calculations, which then makes the steady-state methods\ndeveloped for quantum dot theories applicable to lattice models. We show that\nthe effective temperature of the hot-electron induced by a DC electric field\nbehaves as $T_{\\rm eff}=C\\gamma(\\Omega/\\Gamma)$ with a numerical constant $C$,\ntight-binding parameter $\\gamma$, the Bloch oscillation frequency $\\Omega$ and\nthe damping parameter $\\Gamma$. In the small damping limit $\\Gamma/\\Omega\\to\n0$, the steady-state has a singular property with the electron becoming\nextremely hot in an analogy to the short-circuit effect. This leads to the\nconclusion that the dissipation mechanism cannot be considered as an implicit\nprocess, as treated in equilibrium theories. Finally, using the energy flux\nrelation, we derive a steady-state current for interacting models where only\non-site Green's functions are necessary.",
        "positive": "Nonlocal correlations in a proximity-coupled normal metal: We report evidence of large, nonlocal correlations between two spatially\nseparated normal metals in superconductor/normal-metal (SN) heterostructures,\nwhich manifest themselves a nonlocal voltage generated in response to a driving\ncurrent. Unlike prior experiments in SN heterostructures, the nonlocal\ncorrelations are mediated not by a superconductor, but by a proximity-coupled\nnormal metal. The nonlocal correlations extend over relatively long length\nscales in comparison to the superconduncting case. At very low temperatures, we\nfind a reduction in the nonlocal voltage for small applied currents that cannot\nbe explained by the quasiclassical theory of superconductivity. We believe is a\nsignature of new long-range quantum correlations in the system."
    },
    {
        "anchor": "Electron-nuclear coherent coupling and nuclear spin readout through\n  optically polarized VB- spin states in hBN: Coherent coupling of defect spins with surrounding nuclei along with the\nendowment to read out the latter, are basic requirements for an application in\nquantum technologies. We show that negatively charged boron vacancies (VB-) in\nelectron-irradiated hexagonal boron nitride (hBN) meet these prerequisites. We\ndemonstrate Hahn-echo coherence of the VB- electron spin with a characteristic\ndecay time Tcoh = 15 us, close to the theoretically predicted limit of 18 us\nfor spin defects in hBN. Modulation in the MHz range superimposed on the\nHahn-echo decay curve are shown to be induced by coherent coupling of the VB-\nspin with the three nearest 14N nuclei through a nuclear quadrupole interaction\nof 2.11 MHz. Supporting DFT calculation confirm that the electron-nuclear\ncoupling is confined to the defective layer. Our findings allow an in-depth\nunderstanding of the electron-nuclear interactions of the VB- defect in hBN and\ndemonstrate its strong potential in quantum technologies.",
        "positive": "Topologically distinct Weyl-fermion pairs: on the effect of magnetic\n  tunnelling: A Weyl semimetal has Weyl nodes that always come in pairs with opposite\nchiralities. Notably, different ways of connection between nodes are possible\nand would lead to distinct topologies. Here we identify their differences in\nmany respects from two proposed models with different vorticities. One\nprominent feature is the behaviour of zeroth Landau levels (LLs) under magnetic\nfield. We demonstrate that the magnetic tunnelling does not always expel LLs\nfrom zero energy because the number of zero-energy modes is linked to the\nvorticity of the Weyl nodes, instead of the chirality. Other respects in\ndisorder effects for weak (anti-)localization, surface Fermi arcs, and\nWeyl-node annihilation, are interesting consequences that await future\nexploration."
    },
    {
        "anchor": "Activation energies for spin-reversed excitations in the fractional\n  quantum Hall effect: The activation energy measured in transport experiments in the fractional\nHall regime corresponds to the energy required to create a far separated\nparticle hole pair. We calculate, for several fractional quantum Hall states,\nthe energy gaps for the excitation in which the excited composite fermion\nreverses its spin quantum number. Our results indicate that such spin reversed\nexcitations may be relevant in experimentally accessible regimes.",
        "positive": "A new phenomenon in graphene: The pseudospinorial Zitterbewegung: We foretell a new pseudospin-dependent phenomenon in mono-layer graphene\n(MLG), which is numerically simulated \\emph{via} an innovator nano-spintronic\ndevice. We proposed a novel theoretical procedure for describing the dynamics\nof Dirac fermions, departing from classic theoretical modelling. More\nimportantly, we have found appealing evidences of wiggling anti-phase\noscillations in the probability density time-distribution for each sub-lattice\nstate, which we called pseudospinorial Zitterbewegung effect (PZBE). The PZBE\nundergoes modulated by a robust transient character, with decay time of\nfemtoseconds. Interestingly, several features of the PZBE become tunable, even\nup to fully vanishing it at the vicinity of the Dirac points, as well as for a\nsymmetric pseudospin configuration. We have observed evidences of perfect Klein\ntunneling and perfect anti-Klein backscattering in a single simulation, which\nis unprecedented for Q1D-MLG, as far as we know."
    },
    {
        "anchor": "Dipolar and charged localized excitons in carbon nanotubes: We study both experimentally and theoretically the fundamental interplay of\nexciton localization and polarization in semiconducting single-walled carbon\nnanotubes. From Stark spectroscopy of individual carbon nanotubes at cryogenic\ntemperatures we identify localized excitons as permanent electric dipoles with\ndipole moments of up to 1e{\\AA}. Moreover, we demonstrate field-effect doping\nof localized excitons with an additional charge which results in\ndefect-localized trions. Our findings provide not only fundamental insight into\nthe microscopic nature of localized excitons in carbon nanotubes, they also\nsignify their potential for sensing applications and may serve as guidelines\nfor molecular engineering of exciton-localizing quantum dots in other\natomically thin semiconductors including transition metal dichalcogenides.",
        "positive": "Topological Insulators in Random Lattices: Our understanding of topological insulators is based on an underlying\ncrystalline lattice where the local electronic degrees of freedom at different\nsites hybridize with each other in ways that produce nontrivial band topology,\nand the search for material systems to realize such phases have been strongly\ninfluenced by this. Here we theoretically demonstrate topological insulators in\nsystems with a random distribution of sites in space, i. e., a random lattice.\nThis is achieved by constructing hopping models on random lattices whose ground\nstates possess nontrivial topological nature (characterized e. g., by Bott\nindices) that manifests as quantized conductances in systems with a boundary.\nBy tuning parameters such as the density of sites (for a given range of fermion\nhopping), we can achieve transitions from trivial to topological phases. We\ndiscuss interesting features of these transitions. In two spatial dimensions,\nwe show this for all five symmetry classes (A, AII, D, DIII and C) that are\nknown to host nontrivial topology in crystalline systems. We expect similar\nphysics to be realizable in any dimension and provide an explicit example of a\n$Z_2$ topological insulator on a random lattice in three spatial dimensions.\nOur study not only provides a deeper understanding of the topological phases of\nnon-interacting fermions, but also suggests new directions in the pursuit of\nthe laboratory realization of topological quantum matter."
    },
    {
        "anchor": "Wave functions and edge states in rectangular honeycomb lattices\n  revisited: nanoflakes, armchair and zigzag nanoribbons and nanotubes: Properties of bulk and boundaries of materials can, in general, be quite\ndifferent, both for topological and non-topological reasons. One of the\nsimplest boundary problems to pose is the tight-binding problem of\nnoninteracting electrons on a finite honeycomb lattice. Despite its simplicity,\nthe problem is quite rich and directly related to the physics of graphene. We\nrevisit this long-studied problem and present an analytical derivation of the\nelectron spectrum and wave functions for graphene rectangular derivatives. We\nprovide an exact analytical description of extended and localized states, the\ntransition between them, and a special case of a localized state when the wave\nfunction is nonzero only at the edge sites. The later state has zero energy, we\ndiscuss its existence in zigzag nanoribbons, zigzag nanotubes with number of\nsites along a zigzag edge divisible by 4, and rectangular graphene nanoflakes\nwith an odd number of sites along both zigzag and armchair edges.",
        "positive": "Theory of spin center sensing of diffusion: Surface electric (charge) noise influences spin defects due to fluctuation of\nthe surface charge density and also the electrostatic potential at the crystal\nsurface. Surprisingly, the two-point correlation function of both the charged\nparticles' positions and the surface electrostatic potential strongly\ninfluences the power of the polynomial decay of the electric noise spectral\ndensity; this power is not determined solely by the character of the charge\nfluctuators. Time-dependent crossover behavior near the correlation time of the\nfluctuators, of the spin defect's relaxation and decoherence, provide a\nquantitative fingerprint of the diffusive behavior of charged particles at the\nsurface."
    },
    {
        "anchor": "Spin pumping and inverse spin Hall effect in CoFeB/IrMn heterostructures: High spin to charge conversion efficiency is the requirement for the\nspintronics devices which is governed by spin pumping and inverse spin Hall\neffect (ISHE). In last one decade, ISHE and spin pumping are heavily\ninvestigated in ferromagnet/ heavy metal (HM) heterostructures. Recently\nantiferromagnetic (AFM) materials are found to be good replacement of HMs\nbecause AFMs exhibit terahertz spin dynamics, high spin-orbit coupling, and\nabsence of stray field. In this context we have performed the ISHE in CoFeB/\nIrMn heterostructures. Spin pumping study is carried out for\n$Co_{40}Fe_{40}B_{20} (12\\ nm)/ Cu (3\\ nm)/ Ir_{50}Mn_{50} (t\\ nm)/ AlO_{x} (3\\\nnm)$ samples where \\textit{t} value varies from 0 to 10 nm. Damping of all the\nsamples are higher than the single layer CoFeB which indicates that spin\npumping due to IrMn is the underneath mechanism. Further the spin pumping in\nthe samples are confirmed by angle dependent ISHE measurements. We have also\ndisentangled other spin rectifications effects and found that the spin pumping\nis dominant in all the samples. From the ISHE analysis the real part of spin\nmixing conductance (\\textit{$g_{r}^{\\uparrow \\downarrow}$}) is found to be\n0.704 $\\pm$ 0.003 $\\times$ $10^{18}$ $m^{-2}$.",
        "positive": "Spin dynamics in InAs-nanowire quantum-dots coupled to a transmission\n  line: We study theoretically electron spins in nanowire quantum dots placed inside\na transmission line resonator. Because of the spin-orbit interaction, the spins\ncouple to the electric component of the resonator electromagnetic field and\nenable coherent manipulation, storage, and read-out of quantum information in\nan all-electrical fashion. Coupling between distant quantum-dot spins, in one\nand the same or different nanowires, can be efficiently performed via the\nresonator mode either in real time or through virtual processes. For the latter\ncase we derive an effective spin-entangling interaction and suggest means to\nturn it on and off. We consider both transverse and longitudinal types of\nnanowire quantum-dots and compare their manipulation timescales against the\nspin relaxation times. For this, we evaluate the rates for spin relaxation\ninduced by the nanowire vibrations (phonons) and show that, as a result of\nphonon confinement in the nanowire, this rate is a strongly varying function of\nthe spin operation frequency and thus can be drastically reduced compared to\nlateral quantum dots in GaAs. Our scheme is a step forward to the formation of\nhybrid structures where qubits of different nature can be integrated in a\nsingle device."
    },
    {
        "anchor": "Circular polarization memory effect in enhanced backscattering of light\n  under partially coherent illumination: We experimentally study the propagation of circularly polarized light in the\nsub-diffusion regime by exploiting enhanced backscattering (EBS, also known as\ncoherent backscattering) of light under low spatial coherence illumination. We\ndemonstrate for the first time that circular polarization memory effect exists\nin EBS over a large range of scatterers' sizes in this regime. We show that EBS\nmeasurements under low spatial coherence illumination from the helicity\npreserving and orthogonal helicity channels cross over as the mean free\npathlength of light in media varies, and that the cross point indicates the\ntransition from multiple to double scattering in EBS of light.",
        "positive": "Electron resonant tunneling through InAs/GaAs quantum dots embedded in a\n  Schottky diode with an AlAs insertion layer: Molecular beam epitaxy is employed to manufacture self-assembled InAs/GaAs\nquantum dot Schottky resonant tunneling diodes. By virtue of a thin AlAs\ninsertion barrier, the thermal current is effectively reduced and electron\nresonant tunneling through quantum dots under both forward and reverse biased\nconditions is observed at relatively high temperature of 77K. The ground states\nof quantum dots are found to be at ~0.19eV below the conduction band of GaAs\nmatrix. The theoretical computations are in conformity with experimental data."
    },
    {
        "anchor": "An RF Circuit Model for Carbon Nanotubes: We develop an rf circuit model for single walled carbon nanotubes for both dc\nand capacitively contacted geometries. By modeling the nanotube as a\nnano-transmission line with distributed kinetic and magnetic inductance as well\nas distributed quantum and electrostatic capacitance, we calculate the complex,\nfrequency dependent impedance for a variety of measurement geometries. Exciting\nvoltage waves on the nano-transmission line is equivalent to directly exciting\nthe yet-to-be observed one dimensional plasmons, the low energy excitation of a\nLuttinger liquid.",
        "positive": "Spin-transfer torque in ferromagnetic bilayers generated by anomalous\n  Hall effect and anisotropic magnetoresistance: We propose an experimental scheme to determine the spin-transfer torque\nefficiency excited by the spin-orbit interaction in ferromagnetic bilayers from\nthe measurement of the longitudinal magnetoresistace. Solving a diffusive\nspin-transport theory with appropriate boundary conditions gives an analytical\nformula of the longitudinal charge current density. The longitudinal charge\ncurrent has a term that is proportional to the square of the spin-transfer\ntorque efficiency and that also depends on the ratio of the film thickness to\nthe spin diffusion length of the ferromagnet. Extracting this contribution from\nmeasurements of the longitudinal resistivity as a function of the thickness can\ngive the spin-transfer torque efficiency."
    },
    {
        "anchor": "Superconducting complementary metasurfaces for THz ultrastrong\n  light-matter coupling: A superconducting metasurface operating in the THz range and based on the\ncomplementary metamaterial approach is discussed. Experimental measurements as\na function of temperature and magnetic field display a modulation of the\nmetasurface with a change in transmission amplitude and frequency of the\nresonant features. Such a metasurface is successively used as a resonator for a\ncavity quantum electrodynamic experiment displaying ultrastrong coupling to the\ncyclotron transition of a 2DEG. A finite element modeling is developed and its\nresults are in good agreement with the experimental data. In this system a\nnormalized coupling ratio of $\\frac{\\Omega}{\\omega_c}=0.27$ is measured and a\nclear modulation of the polaritonic states as a function of the temperature is\nobserved.",
        "positive": "Spin currents in rough graphene nanoribbons: Universal fluctuations and\n  spin injection: We investigate spin conductance in zigzag graphene nanoribbons and propose a\nspin injection mechanism based only on graphitic nanostructures. We find that\nnanoribbons with atomically straight, symmetric edges show zero spin\nconductance, but nonzero spin Hall conductance. Only nanoribbons with\nasymmetrically shaped edges give rise to a finite spin conductance and can be\nused for spin injection into graphene. Furthermore, nanoribbons with rough\nedges exhibit mesoscopic spin conductance fluctuations with a universal value\nof $\\mathrm{rms} G_\\mathrm{s}\\approx 0.4 e/4\\pi$."
    },
    {
        "anchor": "Violation of detailed balance in microwave circuits: theory and\n  experiment: We propose a new approach to detailed balance violation in electrical\ncircuits by relying on the scattering matrix formalism commonly used in\nmicrowave electronics. This allows to include retardation effects which are\nparamount at high frequencies. We define the spectral densities of phase space\nangular momentum, heat transfer and cross power, which can serve as criteria\nfor detailed balance violation. We confirm our theory with measurements in the\n4-8 GHz frequency range on several two port circuits of varying symmetries, in\nspace and time. This validates our approach, which will allow to treat quantum\ncircuits at ultra-low temperature.",
        "positive": "Quantum Hall studies of a Semi-Dirac Nanoribbon: Here we comprehensively investigate Landau levels, Hofstadter butterfly and\ntransport properties of a semi-Dirac nanoribbon in a perpendicular magnetic\nfield using a recently developed real-space implementation of the Kubo formula\nbased on Kernel Polynomial Method. A Dirac ribbon is considered to compare and\ncontrast our results for a semi-Dirac system. We find that the Landau levels\nbeing non-equidistant from each other for the semi-Dirac case (true for a Dirac\nas well), the flatness of the energy bands vanishes in the bulk and becomes\ndispersive for a semi-Dirac ribbon in contrast to a Dirac system. This feature\nis most discernible for intermediate values of the external field. We further\ncompute the longitudinal ($\\sigma_{xx}$ and $\\sigma_{yy}$) and the transverse\nor Hall ($\\sigma_{xy}$) conductivities where the Hall conductivity shows a\nfamiliar quantization, namely, $\\sigma_{xy} \\propto 2n$ (the factor `2'\nincludes the spin degeneracy) which is highly distinct from a Dirac system,\nsuch as graphene. We also observe anisotropic behavior in magneto-transport in\na semi-Dirac ribbon owing to the dispersion anomalies in two different\nlongitudinal directions. Our studies may have important ramifications for\nmonolayer phosphorene."
    },
    {
        "anchor": "Integration and characterization of micron-sized YIG structures with\n  very low Gilbert damping on arbitrary substrates: We present a novel process that allows the transfer of monocrystalline\nyttrium-iron-garnet microstructures onto virtually any kind of substrate. The\nprocess is based on a recently developed method that allows the fabrication of\nfreestanding monocrystalline YIG bridges on gadolinium-gallium-garnet. Here the\nbridges' spans are detached from the substrate by a dry etching process and\nimmersed in a watery solution. Using drop casting the immersed YIG platelets\ncan be transferred onto the substrate of choice, where the structures finally\ncan be reattached and thus be integrated into complex devices or experimental\ngeometries. Using time resolved scanning Kerr microscopy and inductively\nmeasured ferromagnetic resonance we can demonstrate that the structures retain\ntheir excellent magnetic quality. At room temperature we find a ferromagnetic\nresonance linewidth of $\\mu_0\\Delta H_{HWHM}\\approx 195\\,\\mu T$ and we were\neven able to inductively measure magnon spectra on a single micron-sized\nyttrium-iron-garnet platelet at a temperature of 5 K. The process is flexible\nin terms of substrate material and shape of the structure. In the future this\napproach will allow for new types of spin dynamics experiments up to now\nunthinkable.",
        "positive": "Proposal for a phase-coherent thermoelectric transistor: Identifying materials and devices which offer efficient thermoelectric\neffects at low temperature is a major obstacle for the development of thermal\nmanagement strategies for low-temperature electronic systems. Superconductors\ncannot offer a solution since their near perfect electron-hole symmetry leads\nto a negligible thermoelectric response; however, here we demonstrate\ntheoretically a superconducting thermoelectric transistor which offers\nunparalleled figures of merit of up to $\\sim 45$ and Seebeck coefficients as\nlarge as a few mV/K at sub-Kelvin temperatures. The device is also\nphase-tunable meaning its thermoelectric response for power generation can be\nprecisely controlled with a small magnetic field. Our concept is based on a\nsuperconductor-normal metal-superconductor interferometer in which the normal\nmetal weak-link is tunnel coupled to a ferromagnetic insulator and a Zeeman\nsplit superconductor. Upon application of an external magnetic flux, the\ninterferometer enables phase-coherent manipulation of thermoelectric properties\nwhilst offering efficiencies which approach the Carnot limit."
    },
    {
        "anchor": "Electronic and optical properties of graphene antidot lattices:\n  Comparison of Dirac and tight-binding models: The electronic properties of graphene may be changed from semimetallic to\nsemiconducting by introducing perforations (antidots) in a periodic pattern.\nThe properties of such graphene antidot lattices (GALs) have previously been\nstudied using atomistic models, which are very time consuming for large\nstructures. We present a continuum model that uses the Dirac equation (DE) to\ndescribe the electronic and optical properties of GALs. The advantages of the\nDirac model are that the calculation time does not depend on the size of the\nstructures and that the results are scalable. In addition, an approximation of\nthe band gap using the DE is presented. The Dirac model is compared with\nnearest-neighbour tight-binding (TB) in order to assess its accuracy. Extended\nzigzag regions give rise to localized edge states, whereas armchair edges do\nnot. We find that the Dirac model is in quantitative agreement with TB for GALs\nwithout edge states, but deviates for antidots with large zigzag regions.",
        "positive": "Dynamics of parafermionic states in transport measurements: Advances in hybrid fractional quantum Hall (FQH)-superconductor platforms\npave the way for realisation of parafermionic modes. We analyse signatures of\nthese non-abelian anyons in transport measurements across devices with\n$\\mathbb{Z}_6$ parafermions (PFs) coupled to an external electrode. Simulating\nthe dynamics of these open systems by a stochastic quantum jump method, we show\nthat a current readout over sufficiently long times constitutes a projective\nmeasurement of the fractional charge shared by two PFs. Interaction of these\ntopological modes with the FQH environment, however, may cause poisoning events\naffecting this degree of freedom which we model by jump operators that describe\nincoherent coupling of PFs with FQH edge modes. We analyse how this gives rise\nto a characteristic three-level telegraph noise in the current, constituting a\nvery strong signature of PFs. We discuss also other forms of poisoning and\nnoise caused by interaction with fractional quasiparticles in the bulk of the\nHall system. We conclude our work with an analysis of four-PF devices, in\nparticular on how the PF fusion algebra can be observed in electrical transport\nexperiments."
    },
    {
        "anchor": "Kondo-effect protected topological surface states on Sb(111): Local density of states and quasiparticle interference phenomena of\nCo/Sb(111) were investigated by scanning tunneling spectroscopy. A sharp peak\nobserved near the Fermi energy is interpreted as a fingerprint of the\nconventional Kondo resonance with the Kondo temperature of K. Moreover, by\nidentifying the interference wavevectors, only the scattering channels relating\nto backscattering confinements are observed for surfaces with and without the\nCo deposition. It reveals that the Kondo effect fully screens the magnetic\nimpurities and thereby suppresses the backscattering of the topological surface\nstate.",
        "positive": "Quantum electron transport in ohmic edge contacts between\n  two-dimensional materials: The metal-semiconductor contact is a major factor limiting the shrinking of\ntransistor dimension to further increase device performance. In-plane edge\ncontacts have the potential to achieve lower contact resistance due to stronger\norbital hybridization compared to conventional top contacts. However, a\nquantitative understanding of the electron transport properties in the edge\ncontact is still lacking. In this work, we present full-band atomistic quantum\ntransport simulations of the graphene/MoS$_2$ edge contact. By using a Wannier\nfunction basis to accurately describe the electronic bands, together with a\nfull self-consistent solution of the electrostatics, we are able to efficiently\nmodel device structures on a micron scale, but with atomic level accuracy. We\nfind that the potential barrier created by trapped charges decays fast with\ndistance away from the interface, and is thus thin enough to enable efficient\ninjection of electrons. This results in Ohmic behavior in its I-V\ncharacteristics, which agrees with experiments. Our results demonstrate the\nrole played by trapped charges in the formation of a Schottky barrier, and how\none can reduce the Schottky barrier height (SBH) by adjusting the relevant\nparameters of the edge contact system. Our framework can be extended\nconveniently to incorporate more general nanostructure geometries. For example,\na full 3D solution of the electrostatics will also lead to better modeling of\nthe electrical potential. Furthermore, better ab-initio calculations can be\nconveniently added to our methods to further improve their accuracy."
    },
    {
        "anchor": "Flat bands in bilayer graphene induced by proximity with polar $h$-BN\n  superlattices: Motivated by the observation of polarization superlattices in twisted\nmultilayers of hexagonal boron nitride ($h$-BN), we address the possibility of\nusing these heterostructures for tailoring the properties of multilayer\ngraphene by means of the electrostatic proximity effect. By using the\ncombination of first-principles and large-scale tight-binding model\ncalculations coupled via the Wannier function approach, we demonstrate the\npossibility of creating a sequence of well-separated flat-band manifolds in\nAB-stacked bilayer graphene at experimentally relevant superlattice\nperiodicities above $\\sim$30 nm. Our calculations show that the details of band\nstructures depend on the local inversion symmetry breaking and the vertical\nelectrical polarization, which are directly related to the atomic arrangement.\nThe results advance the atomistic characterization of graphene-based systems in\na superlattice potential beyond the continuum model.",
        "positive": "Topological skyrmion semimetals: We introduce topological skyrmion semimetal phases of matter, characterized\nby bulk electronic structures with topological defects in ground state\nobservable textures over the Brillouin zone (BZ), rather than topological\ndegeneracies in band structures. We present and characterize toy models for\nthese novel topological phases, focusing on realizing such topological defects\nin the ground state spin expectation value texture over the BZ. We find\ngeneralized Fermi arc bulk-boundary correspondences and chiral anomaly response\nsignatures, including Fermi arc-like states which do not terminate with\ntopological band structure degeneracies in the bulk, but rather with\ntopological defects in the spin texture of bulk insulators. We also consider\nnovel boundary conditions for topological semimetals, in which the 3D bulk is\nmapped to a 2D bulk plus 0D defect. Given the experimental significance of\ntopological semimetals, our work paves the way to broad experimental study of\ntopological skyrmion phases and the quantum skyrmion Hall effect."
    },
    {
        "anchor": "Remarks on thermodynamic properties of a double ring-shaped quantum dot\n  at low and high temperatures: In a recent paper published in this Journal, Khordad and collaborators [J Low\nTemp Phys (2018) 190:200] have studied the thermodynamics properties of a GaAs\ndouble ring-shaped quantum dot under external magnetic and electric fields. In\nthat meritorious research the energy of system was obtained by solving the\nSchr\\\"{o}dinger equation. The radial equation was mapped into a confluent\nhypergeometric differential equation and the differential equation associated\nto $z$ coordinate was mapped into a biconfluent Heun differential equation. In\nthis paper, it is pointed out a misleading treatment on the solution of the\nbiconfluent Heun equation. It is shown that the energy $E_{z}$ can not be\nlabeled with $n_{z}$ and this fact jeopardizes the results of this system. We\ncalculate the partition function with the correct energy spectrum and\nrecalculate the specific heat and entropy as a function of low and high\ntemperatures.",
        "positive": "2D Rutherford-Like Scattering in Ballistic Nanodevices: Ballistic injection in a nanodevice is a complex process where electrons can\neither be transmitted or reflected, thereby introducing deviations from the\notherwise quantized conductance. In this context, quantum rings (QRs) appear as\nmodel geometries: in a semiclassical view, most electrons bounce against the\ncentral QR antidot, which strongly reduces injection efficiency. Thanks to an\nanalogy with Rutherford scattering, we show that a local partial depletion of\nthe QR close to the edge of the antidot can counter-intuitively ease ballistic\nelectron injection. On the contrary, local charge accumulation can focus the\nsemi-classical trajectories on the hard-wall potential and strongly enhance\nreflection back to the lead. Scanning gate experiments on a ballistic QR, and\nsimulations of the conductance of the same device are consistent, and agree to\nshow that the effect is directly proportional to the ratio between the strength\nof the perturbation and the Fermi energy. Our observation surprisingly fits the\nsimple Rutherford formalism in two-dimensions in the classical limit."
    },
    {
        "anchor": "Gapless excitations in strongly fluctuating superconducting wires: We study the low temperature tunneling density of states of thin wires where\nsuperconductivity is destroyed through quantum phase-slip proliferation.\nAlthough this regime is believed to behave as an insulator, we show that for a\nlarge temperature range this phase is characterized by a conductivity falling\noff at most linearly with temperature, and has a gapless excitation spectrum.\nThis novel conducting phase results from electron-electron interaction induced\npair breaking. Also, it may help clarify the low temperature metallic features\nfound in films and wires whose bulk realization is superconducting.",
        "positive": "Scaling of critical wavefunctions at topological Anderson transitions in\n  1D: Topological Anderson transitions, which are direct phase transitions between\ntopologically distinct Anderson localised phases, allow for criticality in 1D\ndisordered systems. We analyse the statistical properties of an emsemble of\ncritical wavefunctions at such transitions. We find that the local moments are\nstrongly inhomogeneous, with significant amplification towards the edges of the\nsystem. In particular, we obtain an analytic expression for the spatial profile\nof the local moments which is valid at all topological Anderson transitions in\n1D, as we verify by direct comparison with numerical simulations of various\nlattice models."
    },
    {
        "anchor": "Coulomb blockade in quantum dots with overlapping resonances: Coulomb blockade (CB) in a quantum dot (QD) with one anomalously broad level\nis considered. In this case many consecutive pronounced CB peaks correspond to\noccupation of one and the same broad level. Between the peaks the electron\njumps from this level to one of the narrow levels and the transmission through\nthe dot at the next resonance essentially repeats that at the previous one.\nThis offers a natural explanation to the recently observed behavior of the\ntransmission phase in an interferometer with a QD. Single particle resonances\nof very different width are natural if the dot is not fully chaotic. This idea\nis illustrated by the numerical simulations for a non-integrable QD whose\nclassical dynamics is intermediate between integrable and chaotic. Possible\nmanifestations for the Kondo experiments in the QD are discussed.",
        "positive": "Widely tunable single-photon source from a carbon nanotube in the\n  Purcell regime: Single-Wall Carbon Nanotubes (SWNTs) are among the very few candidates for\nsingle-photon sources operating in the telecom bands since they exhibit large\nphoton antibunching up to room temperature. However, coupling a nanotube to a\nphotonic structure is highly challenging because of the random location and\nemission wavelength in the growth process. Here, we demonstrate the realization\nof a widely tunable single-photon source by using a carbon nanotube inserted in\nan original repositionable fiber micro-cavity : we fully characterize the\nemitter in the free-space and subsequently form the cavity around the nanotube.\nThis brings an invaluable insight into the emergence of quantum\nelectrodynamical effects. We observe an efficient funneling of the emission\ninto the cavity mode with a strong sub-Poissonian statistics together with an\nup to 6-fold Purcell enhancement factor. By exploiting the cavity feeding\neffect on the phonon wings, we locked the single-photon emission at the cavity\nfrequency over a 4~THz-wide band while keeping the mode width below 80~GHz.\nThis paves the way to multiplexing and multiple qubit coupling."
    },
    {
        "anchor": "Theory of Luminescent Emission in Nanocrystal ZnS:Mn with an Extra\n  Electron: We consider the effect of an extra electron injected into a doped quantum dot\n$ZnS:Mn^{2+}$. The Coulomb interaction and the exchange interaction between the\nextra electron and the states of the Mn ion will mix the wavefunctions, split\nthe impurity energy levels, break the previous selection rules and change the\ntransition probabilities. Using this model of an extra electron in the doped\nquantum dot, we calculated the energy and the wavefunctions, the luminescence\nprobability and the transition lifetime and compare with the experiments. Our\ncalculation shows that two orders of magnitudes of lifetime shortening can\noccur in the transition $^4T_1-^6A_1$ when an extra electron is present.",
        "positive": "Understanding current-driven dynamics of magnetic N\u00e9el walls in\n  heavy metal/ferromagnetic metal/oxide trilayers: We consider analytically current-driven dynamics of magnetic N\\'{e}el walls\nin heavy metal/ferromagnetic metal/oxide trilayers where strong spin-orbit\ncoupling and interfacial Dzyaloshinskii-Moriya interaction (i-DMI) coexist. We\nshow that field-like spin-orbit torque (FL-SOT) with effective field along\n$\\mathbf{n}\\times\\hat{\\mathbf{J}}$ ($\\mathbf{n}$ being the interface normal and\n$\\hat{\\mathbf{J}}$ being the charge current direction) and i-DMI induced torque\ncan both lead to Walker breakdown suppression meanwhile leaving the wall\nmobility (velocity versus current density) unchanged. However, i-DMI itself can\nnot induce the \"universal absence of Walker breakdown\" (UAWB) while FL-SOT\nexceeding a certain threshold can. Finitely-enlarged Walker limits before UAWB\nare theoretically calculated and well explain existing data. In addition,\nchange in wall mobility and even its sign-inversion can be understood only if\nthe anti-damping-like (ADL) SOT is appended. For N\\'{e}el walls in\nferromagnetic-metal layer with both perpendicular and in-plane anisotropies, we\nhave calculated the respective modifications of wall mobility under the\ncoexistence of spin-transfer torque, SOTs and i-DMI. Analytics shows that in\ntrilayers with perpendicular anisotropy strong enough spin Hall angle and\nappropriate sign of i-DMI parameter can lead to sign-inversion in wall mobility\neven under small enough current density, while in those with in-plane\nanisotropy this only occurs for current density in a specific range."
    },
    {
        "anchor": "Spin-statistics relation for quantum Hall states: We prove a generic spin-statistics relation for the fractional quasiparticles\nthat appear in abelian quantum Hall states on the disk. The proof is based on\nan efficient way for computing the Berry phase acquired by a generic\nquasiparticle translated in the plane along a circular path, and on the crucial\nfact that once the gauge-invariant generator of rotations is projected onto a\nLandau level, it fractionalizes among the quasiparticles and the edge. Using\nthese results we define a measurable quasiparticle fractional spin that\nsatisfies the spin-statistics relation. As an application, we predict the value\nof the spin of the composite-fermion quasielectron proposed by Jain; our\nnumerical simulations agree with that value. We also show that Laughlin's\nquasielectrons satisfy the spin-statistics relation, but carry the wrong spin\nto be the anti-anyons of Laughlin's quasiholes. We continue by highlighting the\nfact that the statistical angle between two quasiparticles can be obtained by\nmeasuring the angular momentum whilst merging the two quasiparticles. Finally,\nwe show that our arguments carry over to the non-abelian case by discussing\nexplicitly the Moore-Read wavefunction.",
        "positive": "A thermodynamic theory of filamentary resistive switching: We present a phenomenological theory of filamentary resistive random access\nmemory (RRAM) describing the commonly observed features of their\ncurrent-voltage characteristics. Our approach follows the approach of\nthermodynamic theory developed earlier for chalcogenide memory and threshold\nswitches and largely independent of their microscopic details. It explains,\nwithout adjustable parameters, such features as the domains of filament\nformation and switching, voltage independent current in SET and current\nindependent voltage in RESET regimes, the relation between the set and reset\nvoltages, filament resistance independent of its length, etc. Furthermore, it\nexpresses the observed features through the material and circuitry parameters\nthus paving a way to device improvements."
    },
    {
        "anchor": "Manipulating Magnetization of a Nanomagnet by Surface Acoustic Waves:\n  Spin-Rotation Mechanism: We show that the magnetic moment of a nanoparticle embedded in the surface of\na solid can be switched by surface acoustic waves (SAW) in the GHz frequency\nrange via a universal mechanism that does not depend on the structure of the\nparticle and the structure of the substrate. It is based upon generation of the\neffective ac magnetic field in the coordinate frame of the nanoparticle by the\nshear deformation of the surface due to SAW. The magnetization reversal occurs\nvia a consecutive absorption of surface phonons of the controlled variable\nfrequency. We derive analytical equations governing this process and solve them\nnumerically for the practical range of parameters.",
        "positive": "The stochastic dynamics of micron and nanoscale elastic cantilevers in\n  fluid: fluctuations from dissipation: The stochastic dynamics of micron and nanoscale cantilevers immersed in a\nviscous fluid are quantified. Analytical results are presented for long slender\ncantilevers driven by Brownian noise. The spectral density of the noise force\nis not assumed to be white and the frequency dependence is determined from the\nfluctuation-dissipation theorem. The analytical results are shown to be useful\nfor the micron scale cantilevers that are commonly used in atomic force\nmicroscopy. A general thermodynamic approach is developed that is valid for\ncantilevers of arbitrary geometry as well as for arrays of multiple cantilevers\nwhose stochastic motion is coupled through the fluid. It is shown that the\nfluctuation-dissipation theorem permits the calculation of stochastic\nquantities via straightforward deterministic methods. The thermodynamic\napproach is used with deterministic finite element numerical simulations to\nquantify the autocorrelation and noise spectrum of cantilever fluctuations for\na single micron scale cantilever and the cross-correlations and noise spectra\nof fluctuations for an array of two experimentally motivated nanoscale\ncantilevers as a function of cantilever separation. The results are used to\nquantify the noise reduction possible using correlated measurements with two\nclosely spaced nanoscale cantilevers."
    },
    {
        "anchor": "Long-range Coulomb interaction effects on the surface Dirac electron\n  system of a three-dimensional topological insulator: The surface state of a three-dimensional topological insulator forms a\ntwo-dimensional massless Dirac electron system. In Dirac electron systems,\nCoulomb interaction is not screened due to the small density of states at the\nFermi energy and thus the long-range Coulomb interaction (LRCI) plays a crucial\nrole. In this paper, we investigate the surface state with chemical potential\n$\\mu=0$ in the presence of the LRCI using the Wilsonian renormalization group.\nWe first check the Fermi velocity enhancement in the surface Dirac system,\nwhich also occurs in a usual Dirac electron system. The most remarkable feature\nof the surface Dirac system is that the Dirac Hamiltonian contains not pseudo\nspin but real spin Pauli matrices. Because of this feature, we find the\ng-factor enhancement, which is a unique property of the surface Dirac system.\nWe also investigate the explicit form of the spin susceptibility and find that\nthe spin susceptibility is enhanced in the presence of the LRCI.",
        "positive": "Confined Electron and Hole States in Semiconducting Carbon Nanotube\n  sub-10 nm Artificial Quantum Dots: We show that quantum confinement in the valence and conduction bands of\nsemiconducting single-walled carbon nanotubes can be engineered by means of\nartificial defects. This ability holds potential for designing future\nnanotube-based quantum devices such as electrically driven room-temperature\nsingle-photon sources emitting at telecom-wavelength. Using Ar$^{+}$ and\nN$^{+}$ ion-induced defects, intrananotube quantum dots with sub-10 nm lateral\nsizes are created, giving rise to quantized electronic bound states with level\nspacings of the order of 100 meV and larger. Using low-temperature scanning\ntunneling spectroscopy, we resolve the energy and real space properties of the\nquantized states and compare them with theoretical model calculations. By\nsolving the Schr\\\"odinger equation over a one-dimensional piecewise constant\npotential model, the effects of inhomogeneous defect scattering strength as\nwell as surface variations in the Au(111) substrate on the quantized states\nstructure are remarkably well reproduced. Furthermore, using ab-initio\ncalculations, we demonstrate that defect structures such as vacancies,\ndi-vacancies and chemisorbed nitrogen ad-atoms constitute strong scattering\ncenters able to form quantum dots with clear signatures of discrete bound\nstates as observed experimentally. The ab-initio simulations also allowed to\nstudy the scattering strength profile as a function of energy for different\ndefect combinations, supporting the potential of highly stable double vacancies\nfor practical applications at room temperature."
    },
    {
        "anchor": "We cannot believe we overlooked these Majorana discoveries: In 2011-2012 we performed experiments on hybrid superconductor-semiconductor\nnanowire devices which yielded signatures of Majorana fermions based on\nzero-bias peaks in tunneling measurements. The research field that grew out of\nthose findings and other contemporary works has advanced significantly, and a\nlot of new knowledge and insights were gained. However, key smoking gun\nevidence of Majorana is still lacking. In this paper, we report that while\nreviewing our old data recently, armed with a decade of knowledge, we realized\nthat back in 2012 our results contained two breakthrough Majorana discoveries.\nSpecifically, we have observed quantized zero-bias peaks, the hallmark of ideal\nMajorana states. Furthermore, we have observed the closing and re-opening of\nthe induced gap perfectly correlated with the emergence of the zero-bias peak -\nclear evidence of the topological quantum phase superconducting transition.\nThese insights should pave the way to topological Majorana qubits, and you\nshould also check supplementary information for important disclosures.",
        "positive": "Effect of Coulomb carrier drag and terahertz plasma instability in\n  p+-p-i-n-n+ graphene tunneling transistor structures: We evaluate the influence of the Coulomb drag of the electrons and holes in\nthe gated n- and p-regions by the ballistic electrons and holes generated in\nthe depleted i-region due to the interband tunneling on the current-voltage\ncharacteristics and impedance of the p+-p-i-n-n+ graphene tunneling transistor\nstructures (GTTSs). The drag leads to a current amplification in the gated n-\nand p-regions and a positive feedback between the amplified dragged current and\nthe injected tunneling current. A sufficiently strong drag can result in the\nnegative real part of the GTTS impedance enabling the plasma instability and\nthe self-excitation of the plasma oscillations in the terahertz (THz) frequency\nrange. This effect might be used for the generation of the THz radiation."
    },
    {
        "anchor": "Asymmetry-induced resistive switching in Ag-Ag$_{2}$S-Ag memristors\n  enabling a simplified atomic-scale memory design: Prevailing models of resistive switching arising from electrochemical\nformation of conducting filaments across solid state ionic conductors commonly\nattribute the observed polarity of the voltage-biased switching to the sequence\nof the active and inert electrodes confining the resistive switching memory\ncell. Here we demonstrate equivalent, stable switching behavior in metallic\nAg-Ag$_{2}$S-Ag nanojunctions at room temperature. Our experimental results and\nnumerical simulations reveal that the polarity of the switchings is solely\ndetermined by the geometrical asymmetry of the electrode surfaces. By the\nlithographical design of a proof of principle device we demonstrate the merits\nof simplified fabrication of atomic-scale, robust planar Ag$_{2}$S memory\ncells.",
        "positive": "Momentum resolved tunneling into the Pfaffian and anti-Pfaffian edges: We calculate the electron spectral functions at the edges of the Moore-Read\nPfaffian and anti-Pfaffian fractional quantum Hall states, in the clean limit.\nWe show that their qualitative differences can be probed using momentum\nresolved tunneling, thus providing a method to unambiguously distinguish which\none is realized in the fractional quantum Hall state observed at filling factor\n$\\nu=5/2$. We further argue that edge reconstruction, which may be less\nimportant in the first excited Landau level (LL) than in the lowest LL, can\nalso be detected this way if present."
    },
    {
        "anchor": "Entanglement fidelity for electron-electron interaction in strongly\n  coupled semiclassical plasma and under external fields: This paper presents the effects of AB-flux field and electric field on\nelectron-electron interaction, encircled by a strongly coupled semiclassical\nplasma. We found that weak external fields are required to perpetuate a\nlow-energy elastic electron-electron interaction in a strongly coupled\nsemiclassical plasma. The entanglement fidelity in the interaction process has\nbeen examined. We have used partial wave analysis to derive the entanglement\nfidelity. We found that for a weak electric field, the fidelity ratio for\nelectron-electron interaction increase as projectile energy increase but\nremains constant or almost zero for a strong electric field. Our results\nprovide an invaluable information on how the efficiency of entanglement\nfidelity for a low-energy elastic electron-electron interaction in a strongly\ncoupled semiclassical plasma can be influenced by the presence of external\nfields.",
        "positive": "Hydrogenation-induced ferromagnetism on graphite surfaces: We calculate the electronic structure and magnetic properties of hydrogenated\ngraphite surfaces using van der Waals density functional theory (DFT) and model\nHamiltonians. We find, as previously reported, that the interaction between\nhydrogen atoms on graphene favors adsorption on different sublattices along\nwith an antiferromagnetic coupling of the induced magnetic moments. On the\ncontrary, when hydrogenation takes place on the surface of graphene multilayers\nor graphite (Bernal stacking), the interaction between hydrogen atoms competes\nwith the different adsorption energies of the two sublattices. This competition\nmay result in all hydrogen atoms adsorbed on the same sublattice and, thereby,\nin a ferromagnetic state for low concentrations. Based on the exchange\ncouplings obtained from the DFT calculations, we have also evaluated the Curie\ntemperature by mapping this system onto an Ising-like model with randomly\nlocated spins. Remarkably, the long-range nature of the magnetic coupling in\nthese systems makes the Curie temperature size dependent and larger than room\ntemperature for typical concentrations and sizes."
    },
    {
        "anchor": "The effects of cap layer thickness on the performance of InGaN/GaN MQW\n  solar cell: Following letter introduces a theoretical approach to investigate the effect\nof two-step GaN barrier layer growth methodology on the performance of\nInGaN/GaN MQW solar cell, in which a lower temperature GaN cap layer was grown\non top of each quantum well followed by a higher temperature GaN barrier layer.\nDifferent growth conditions would cause changes in the concentration of trap\nlevel density of states and imperfection sites. The simulation and comparison\nof 3 samples each with different cap layer thickness, reveals the fact that\nincreasing cap layer thickness results in higher quantum efficiency, improved\nshort circuit density of current and 3.2% increase of the fill factor.",
        "positive": "Topological acoustic triple point: Acoustic phonon in a crystalline solid is a well-known and ubiquitous example\nof elementary excitation with a triple degeneracy in the band structure.\nBecause of the Nambu-Goldstone theorem, this triple degeneracy is always\npresent in the phonon band structure. Here, we show that the triple degeneracy\nof acoustic phonons can be characterized by a topological charge $\\mathfrak{q}$\nthat is a property of three-band systems with $\\mathcal{PT}$ symmetry, where\n$\\mathcal{P}$ and $\\mathcal{T}$ are the inversion and the time-reversal\nsymmetries, respectively. We therefore call triple points with nontrivial\n$\\mathfrak{q}$ the topological acoustic triple point (TATP). The topological\ncharge $\\mathfrak{q}$ can equivalently be characterized by the skyrmion number\nof the longitudinal mode, or by the Euler number of the transverse modes, and\nthis strongly constrains the nodal structure around the TATP. The TATP can also\nbe symmetry-protected at high-symmetry momenta in the band structure of phonons\nand spinless electrons by the $O_h$ and the $T_h$ groups. The nontrivial\nwavefunction texture around the TATP can induce anomalous thermal transport in\nphononic systems and orbital Hall effect in electronic systems. Our theory\ndemonstrates that the gapless points associated with the Nambu-Goldstone\ntheorem are an avenue for discovering new classes of degeneracy points with\ndistinct topological characteristics."
    },
    {
        "anchor": "Hierarchy of Hofstadter states and replica quantum Hall ferromagnetism\n  in graphene superlattices: Self-similarity and fractals have fascinated researchers across various\ndisciplines. In graphene placed on boron nitride and subjected to a magnetic\nfield, self-similarity appears in the form of numerous replicas of the original\nDirac spectrum, and their quantization gives rise to a fractal pattern of\nLandau levels, referred to as the Hofstadter butterfly. Here we employ\ncapacitance spectroscopy to probe directly the density of states (DoS) and\nenergy gaps in this spectrum. Without a magnetic field, replica spectra are\nseen as pronounced DoS minima surrounded by van Hove singularities. The\nHofstadter butterfly shows up as recurring Landau fan diagrams in high fields.\nElectron-electron interactions add another twist to the self-similar behaviour.\nWe observe suppression of quantum Hall ferromagnetism, a reverse Stoner\ntransition at commensurable fluxes and additional ferromagnetism within replica\nspectra. The strength and variety of the interaction effects indicate a large\nplayground to study many-body physics in fractal Dirac systems.",
        "positive": "Spin Relaxation in Quasi-1D GaAs Mesowires: Control via Electric Field\n  and Aspect Ratio: We report on the measurements of spin relaxation in GaAs\nquasi-one-dimensional mesowires, relying on spin noise spectroscopy, thus\nadding to the existing body of spin relaxation studies in bulk, two-dimensional\nand zero dimensional systems. In addition to temperature and magnetic field\ndependence, we modify the spin relaxation time via applied electric field and\naspect ratio of the mesowires, suggesting that scalable spintronics devices\nwith controllable spin relaxation are achievable. Overall, we observed higher\nspin-relaxation time in mesowires compared to bulk with a spin noise exhibiting\nDyakonov-Perel scattering and other scattering behavior. Spectral spin noise\ndata are interpreted in part via Glazov-Sherman model, where both, diffusive\nand ballistic spin relaxation are accounted for."
    },
    {
        "anchor": "Ultrafast charging in a two-photon Dicke quantum battery: We consider a collection of two level systems, such as qubits, embedded into\na microwave cavity as a promising candidate for the realization of high power\nquantum batteries. In this perspective, the possibility to design devices where\nthe conventional single-photon coupling is suppressed and the dominant\ninteraction is mediated by two-photon processes is investigated, opening the\nway to an even further enhancement of the charging performance. By solving a\nDicke model with both single- and two-photon coupling we determine the range of\nparameters where the latter unconventional interaction dominates the dynamics\nof the system leading to better performances both in the charging times and\naverage charging power of the QB compared to the single-photon case. In\naddition, the scaling of the maximum stored energy, fluctuations and charging\npower with the finite number of qubits N is inspected. While the energy and\nfluctuations scale linearly with N, the quadratic growth of the average power\nleads to a relevant improvement of the charging performance of quantum\nbatteries based on this scheme with respect to the purely single-photon\ncoupling case. Moreover, it is shown that the charging process is progressively\nfaster by increasing the coupling from the weak to the ultra-strong regime.",
        "positive": "Stokes flow around an obstacle in viscous two-dimensional electron\n  liquid: The electronic analog of the Poiseuille flow is the transport in a narrow\nchannel with disordered edges that scatter electrons in a diffuse way. In the\nhydrodynamic regime, the resistivity decreases with temperature, referred to as\nthe Gurzhi effect, distinct from conventional Ohmic behaviour. We studied\nexperimentally an electronic analog of the Stokes flow around a disc immersed\nin a two-dimensional viscous liquid. The circle obstacle results in an additive\ncontribution to resistivity. If specular boundary conditions apply, it is no\nlonger possible to detect Poiseuille type flow and the Gurzhi effect. However,\nin flow through a channel with a circular obstacle, the resistivity decreases\nwith temperature. By tuning the temperature, we observed the transport\nsignatures of the ballistic and hydrodynamic regimes on the length scale of\ndisc size. Our experimental results confirm theoretical predictions."
    },
    {
        "anchor": "Stability of a Magnetically Levitated Nanomagnet in Vacuum: Effects of\n  Gas and Magnetization Damping: In the absence of dissipation a non-rotating magnetic nanoparticle can be\nstably levitated in a static magnetic field as a consequence of the spin origin\nof its magnetization. Here we study the effects of dissipation on the stability\nof the system, considering the interaction with the background gas and the\nintrinsic Gilbert damping of magnetization dynamics. At large applied magnetic\nfields we identify magnetization switching induced by Gilbert damping as the\nkey limiting factor for stable levitation. At low applied magnetic fields and\nfor small particle dimensions magnetization switching is prevented due to the\nstrong coupling of rotation and magnetization dynamics, and the stability is\nmainly limited by the gas-induced dissipation. In the latter case, high vacuum\nshould be sufficient to extend stable levitation over experimentally relevant\ntimescales. Our results demonstrate the possibility to experimentally observe\nthe phenomenon of quantum spin stabilized magnetic levitation.",
        "positive": "Effects of uniaxial pressure on the quantum tunneling of magnetization\n  in a high-symmetry Mn12 single-molecule magnet: The symmetry of single-molecule magnets dictates their spin quantum dynamics,\ninfluencing how such systems relax via quantum tunneling of magnetization\n(QTM). By reducing a system's symmetry, through the application of a magnetic\nfield or uniaxial pressure, these dynamics can be modified. We report\nmeasurements of the magnetization dynamics of a crystalline sample of the\nhigh-symmetry [Mn12O12(O2CMe)16(MeOH)4]MeOH single-molecule magnet as a\nfunction of uniaxial pressure applied either parallel or perpendicular to the\nsample's \"easy\" magnetization axis. At temperatures between 1.8 and 3.3 K,\nmagnetic hysteresis loops exhibit the characteristic steplike features that\nsignal the occurrence of QTM. After applying uniaxial pressure to the sample in\nsitu, both the magnitude and field position of the QTM steps changed. The step\nmagnitudes were observed to grow as a function of pressure in both arrangements\nof pressure, while pressure applied along (perpendicular to) the sample's easy\naxis caused the resonant-tunneling fields to increase (decrease). These\nobservations were compared with simulations in which the system's Hamiltonian\nparameters were changed. From these comparisons, we determined that parallel\npressure induces changes to the second-order axial anisotropy parameter as well\nas either the fourth-order axial or fourth-order transverse parameter, or to\nboth. In addition, we find that pressure applied perpendicular to the easy axis\ninduces a rhombic anisotropy E ~ D/2000 per kbar that can be understood as\nderiving from a symmetry-breaking distortion of the molecule."
    },
    {
        "anchor": "Critical magnetic flux for Weyl points in the three-dimensional\n  Hofstadter model: We investigate the band structure of the three-dimensional Hofstadter model\non cubic lattices, with an isotropic magnetic field oriented along the diagonal\nof the cube with flux $\\Phi=2 \\pi \\cdot m /n$, where $m,n$ are co-prime\nintegers. Using reduced exact diagonalization in momentum space, we show that,\nat fixed $m$, there exists an integer $n(m)$ associated with a specific value\nof the magnetic flux, that we denote by $\\Phi_c(m) \\equiv 2 \\pi \\cdot m/n(m)$,\nseparating two different regimes. The first one, for fluxes $\\Phi<\\Phi_c(m)$,\nis characterized by complete band overlaps, while the second one, for\n$\\Phi>\\Phi_c(m)$, features isolated band touching points in the density of\nstates and Weyl points between the $m$- and the $(m+1)$-th bands. In the\nHasegawa gauge, the minimum of the $(m+1)$-th band abruptly moves at the\ncritical flux $\\Phi_c(m)$ from $k_z=0$ to $k_z=\\pi$. We then argue that the\nlimit for large $m$ of $\\Phi_c(m)$ exists and it is finite: $\\lim_{m\\to \\infty}\n\\Phi_c(m) \\equiv \\Phi_c$. Our estimate is $\\Phi_c/2\\pi=0.1296(1)$. Based on the\nvalues of $n(m)$ determined for integers $m\\leq60$, we propose a mathematical\nconjecture for the form of $\\Phi_c(m)$ to be used in the large-$m$ limit. The\nasymptotic critical flux obtained using this conjecture is $\\Phi_c^{{\\rm\n(conj)}}/2\\pi=7/54$.",
        "positive": "Strongly bound excitons dominate electronic relaxation in resonantly\n  excited twisted bilayer graphene: When two sheets of graphene stack in a twisted bilayer graphene (tBLG)\nconfiguration, the resulting constrained overlap between interplanar 2p\norbitals produce angle-tunable electronic absorption resonances. Using a novel\ncombination of multiphoton transient absorption (TA) microscopy and TEM, we\nresolve the resonant electronic structure, and ensuing electronic relaxation\ninside single tBLG domains. Strikingly, we find that the transient electronic\npopulation in resonantly excited tBLG domains is enhanced many fold, forming a\nmajor electronic relaxation bottleneck. 2-photon TA microscopy shows this\nbottleneck effect originates from a strongly bound, dark exciton state lying\n0.37 eV below the 1-photon absorption resonance. This stable coexistence of\nstrongly bound excitons alongside free-electron continuum states has not been\npreviously observed in a metallic, 2D material."
    },
    {
        "anchor": "Deterministic preparation of spin qubits in droplet etched GaAs quantum\n  dots using quasi-resonant excitation: We present a first comprehensive study on deterministic spin preparation\nemploying excited state resonances of droplet etched GaAs quantum dots. This\nachievement facilitates future investigations of spin qubit based quantum\nmemories using the GaAs quantum dot material platform. By observation of\nexcitation spectra for a range of fundamental excitonic transitions the\nproperties of different quantum dot energy levels, i.e. shells, are revealed.\nThe innovative use of polarization resolved excitation and detection in\nquasi-resonant excitation spectroscopy facilitates determination of $85$ $\\%$\nmaximum spin preparation fidelity - irrespective of the relative orientations\nof lab and quantum dot polarization eigenbases. Additionally, the\ncharacteristic non-radiative decay time is investigated as a function of ground\nstate, excitation resonance and excitation power level, yielding decay times as\nlow as $29$ ps for s-p-shell exited state transitions. Finally, by time\nresolved correlation spectroscopy it is demonstrated that the employed\nexcitation scheme has a significant impact on the electronic environment of\nquantum dot transitions thereby influencing its charge and coherence.",
        "positive": "Probing Thermally Activated Atomic and Nanocrystalline Defect Motion\n  through Noise Processes in RuO$_2$ Nanowires: The present-day nanodevice dimensions continuously shrink, with the aim to\nprolong Moore's law. As downsizing meticulously persists, undesirable dynamic\ndefects, which cause low-frequency noise and structural instability, play\ndetrimental roles on limiting the ultimate performance and reliability of\nminiaturized devices. A good understanding and a meaningful control of the\ndefect kinetics then become fundamental and urgent issues. Here we report\nobservations of thermally activated atomic defect motion as well as\nnanocrystalline defect motion through electrical noise processes in metallic\nRuO$_2$ rutile nanowires around room temperature. First, we extract the energy\ndistribution function and the number density of mobile atomic defects (oxygen\nvacancies). Second, we obtain the geometrical size, grain-boundary bonding\nstrength, and relaxation times of dynamic nanocrystallites. Our results show\nclearly a powerful probe for effective and noninvasive characterizations of\nnanostructures and nanomaterials for which quantitative information about\nmechanical hardness, breakdown current density, and/or resistance noise is\nessential."
    },
    {
        "anchor": "Superlattice with hot electron injection: an approach to a Bloch\n  oscillator: A semiconductor superlattice with hot electron injection into the miniband is\nconsidered. The injection changes the stationary distribution function and\nresults in a qualitative change of the frequency behaviour of the differential\nconductivity. In the regime with Bloch oscillating electrons and injection into\nthe upper part of the miniband the region of negative differential conductivity\nis shifted from low frequencies to higher frequencies. We find that the dc\ndifferential conductivity can be made positive and thus the domain instability\ncan be suppressed. At the same time the high-frequency differential\nconductivity is negative above the Bloch frequency. This opens a new way to\nmake a Bloch oscillator operating at THz frequencies.",
        "positive": "Nanosecond-timescale low error switching of in-plane magnetic tunnel\n  junctions through dynamic Oersted-field assisted spin-Hall effect: We investigate fast-pulse switching of in-plane-magnetized magnetic tunnel\njunctions (MTJs) within 3-terminal devices in which spin-transfer torque is\napplied to the MTJ by the giant spin Hall effect. We measure reliable\nswitching, with write error rates down to $10^{-5}$, using current pulses as\nshort as just 2 ns in duration. This represents the fastest reliable switching\nreported to date for any spin-torque-driven magnetic memory geometry, and\ncorresponds to a characteristic time scale that is significantly shorter than\npredicted possible within a macrospin model for in-plane MTJs subject to\nthermal fluctuations at room temperature. Using micromagnetic simulations, we\nshow that in the 3-terminal spin-Hall devices the Oersted magnetic field\ngenerated by the pulse current strongly modifies the magnetic dynamics excited\nby the spin-Hall torque, enabling this unanticipated performance improvement.\nOur results suggest that in-plane MTJs controlled by Oersted-field-assisted\nspin-Hall torque are a promising candidate for both cache memory applications\nrequiring high speed and for cryogenic memories requiring low write energies."
    },
    {
        "anchor": "Control of electron trapping effects in graphene quantum dots via light\n  polarization state: We theoretically analyze the scattering process of an electron on a graphene\nquantum dot (GQD) exposed to an external light irradiation. We prove that for\nsuitable choices of the light polarization state, there emerge scattering\nresonances, characterized by electron trapping effects inside the GQD.",
        "positive": "Abnormal Critical Fluctuations Revealed by Magnetic Resonance in the\n  Two-Dimensional Ferromagnetic Insulators: Phase transitions and critical phenomena, which are dominated by fluctuations\nand correlations, are one of the fields replete with physical paradigms and\nunexpected discoveries. Especially for two-dimensional magnetism, the\nlimitation of the Ginzburg criterion leads to enhanced fluctuations breaking\ndown the mean-field theory near a critical point. Here, by means of magnetic\nresonance, we investigate the behavior of critical fluctuations in the\ntwo-dimensional ferromagnetic insulators $\\rm CrXTe_3 (X=Si, Ge)$. After\nderiving the classical and quantum models of magnetic resonance, we deem the\ndramatic anisotropic shift of the measured $g$ factor to originate from\nfluctuations with anisotropic interactions. The deduction of the $g$ factor\nbehind the fluctuations is consistent with the spin-only state (${g\\approx}$\n2.050(10) for $\\rm CrSiTe_3$ and 2.039(10) for $\\rm CrGeTe_3$). Furthermore,\nthe abnormal enhancement of $g$ shift, supplemented by specific heat and\nmagnetometry measurements, suggests that $\\rm CrSiTe_3$ exhibits a more typical\ntwo-dimensional nature than $\\rm CrGeTe_3$ and may be closer to the quantum\ncritical point."
    },
    {
        "anchor": "Quantum Hall Effect on the Hofstadter Butterfly: Motivated by recent experimental attempts to detect the Hofstadter butterfly,\nwe numerically calculate the Hall conductivity in a modulated two-dimensional\nelectron system with disorder in the quantum Hall regime. We identify the\ncritical energies where the states are extended for each of butterfly subbands,\nand obtain the trajectory as a function of the disorder. Remarkably, we find\nthat when the modulation becomes anisotropic, the critical energy branches\naccompanying a change of the Hall conductivity.",
        "positive": "Exact time-evolving scattering states in open quantum-dot systems with\n  an interaction: Discovery of time-evolving resonant states: We study exact time-evolving many-electron states of an open double\nquantum-dot system with an interdot Coulomb interaction. A systematic\nconstruction of the time-evolving states for arbitrary initial conditions is\nproposed. For any initial states of one- and two-electron plane waves on the\nelectrical leads, we obtain exact solutions of the time-evolving scattering\nstates, which converge to known stationary scattering eigenstates in the\nlong-time limit. For any initial states of localized electrons on the quantum\ndots, we find exact time-evolving states of a new type, which we refer to as\ntime-evolving resonant states. In contrast to stationary resonant states, whose\nwave functions spatially diverge and not normalizable, the time-evolving\nresonant states are normalizable since their wave functions are restricted to a\nfinite space interval due to causality. The exact time-evolving resonant states\nenable us to calculate the time-dependence of the survival probability of\nelectrons on the quantum dots for the system with the linearized dispersions.\nIt decays exponentially in time on one side of an exponential point of\nresonance energies while, on the other side, it oscillates during the decay as\na result of the interference of the two resonance energies."
    },
    {
        "anchor": "Quantitative Simulation of the Superconducting Proximity Effect: A numerical method is developed to calculate the transition temperature of\ndouble or multi-layers consisting of films of super- and normal conductors. The\napproach is based on a dynamic interpretation of Gorkov's linear gap equation\nand is very flexible. The mean free path of the different metals, transmission\nthrough the interface, ratio of specular reflection to diffusive scattering at\nthe surfaces, and fraction of diffusive scattering at the interface can be\nincluded. Furthermore it is possible to vary the mean free path and the BCS\ninteraction NV in the vicinity of the interface. The numerical results show\nthat the normalized initial slope of an SN double layer is independent of\nalmost all film parameters except the ratio of the density of states. There are\nonly very few experimental investigations of this initial slope and they\nconsist of Pb/Nn double layers (Nn stands for a normal metal). Surprisingly the\ncoefficient of the initial slope in these experiments is of the order or less\nthan 2 while the (weak coupling) theory predicts a value of about 4.5. This\ndiscrepancy has not been recognized in the past. The autor suggests that it is\ndue to strong coupling behavior of Pb in the double layers. The strong coupling\ngap equation is evaluated in the thin film limit and yields the value of 1.6\nfor the coefficient. This agrees much better with the few experimental results\nthat are available.\n  PACS: 74.45.+r, 74.62.-c, 74.20.Fg",
        "positive": "Spin inversion in fluorinated graphene n-p junction: We consider a dilute fluorinated graphene nanoribbon as a spin-active\nelement. The fluorine adatoms introduce a local spin-orbit Rashba interaction\nthat induces spin-precession for electron passing by. In the absence of the\nexternal magnetic field the transport is dominated by multiple scattering by\nadatoms which cancels the spin precession effects, since the direction of the\nspin precession depends on the electron momentum. Accumulation of the spin\nprecession effects is possible provided that the Fermi level electron passes\nmany times near the same adatom with the same momentum. In order to arrange for\nthese conditions a circular n-p junction can be introduced to the ribbon by\ne.g. potential of the tip of an atomic force microscope. In the quantum Hall\nconditions the electron current gets confined along the junction. The electron\nspin interaction with the local Rashba field changes with the lifetime of the\nquasi-bound states that is controlled with the coupling of the junction to the\nedge of the ribbon. We demonstrate that the spin-flip probability can be\nincreased in this manner by as much as three orders of magnitude."
    },
    {
        "anchor": "SO(3) symmetry between Neel and ferromagnetic order parameters for\n  graphene in a magnetic field: I consider the Hubbard model of graphene in an external magnetic field and in\nthe Hartree-Fock approximation. In the continuum limit, the ground state energy\nat half filling becomes nearly symmetric under rotations of the three-component\nvector (N1,N2,m), with the first two components representing the Neel order\nparameter orthogonal to and the third component the magnetization parallel with\nthe external magnetic field. When the symmetry breaking effects arising from\nthe lattice, Zeeman coupling, and higher Landau levels are included the system\ndevelops a quantum critical point at which the antiferromagnetic order\ndisappears and the magnetization has a kink. The observed incompressible state\nat filling factor one is argued to arise due to a finite third component of the\nNeel order parameter at these electron densities. Recent experiments appear\nconsistent with vanishing N1 and N2, and finite N3, at the filling factors zero\nand one, respectively.",
        "positive": "Hamiltonian approach to the ac Josephson effect in\n  superconducting-normal hybrid systems: The ac Josephson effect in hybrid systems of a normal mesoscopic conductor\ncoupled to two superconducting (S) leads is investigated theoretically. A\ngeneral formula of the ac components of time-dependent current is derived which\nis valid for arbitrary interactions in the normal region. We apply this formula\nto analyze a S-normal-S system where the normal region is a noninteracting\nsingle level quantum dot. We report the physical behavior of time-averaged\nnonequilibrium distribution of electrons in the quantum dot, the formation of\nAndreev bound states, and ac components of the time-dependent current. The\ndistribution is found to exhibit a population inversion; and all Andreev bound\nstates between the superconducting gap $\\Delta$ carry the same amount of\ncurrent and in the same flow direction. The ac components of time-dependent\ncurrent show strong oscillatory behavior in marked contrast to the subharmonic\ngap structure of the average current."
    },
    {
        "anchor": "Tunneling in Nanoscale Devices: Theoretical treatments of tunneling in electronic devices are often based on\none-dimensional (1D) approximations. Here we show that for many nanoscale\ndevices, such as widely studied semiconductor gate-defined quantum dots, 1D\napproximations yield an incorrect functional dependence on the tunneling\nparameters (e.g., lead width and barrier length) and an incorrect magnitude for\nthe transport conductance. Remarkably, the physics of tunneling in 2D or 3D\nalso yields transport behavior that appears classical (like Ohm's law), even\ndeep in the quantum regime.",
        "positive": "A single hole spin with enhanced coherence in natural silicon: Semiconductor spin qubits based on spin-orbit states are responsive to\nelectric field excitation allowing for practical, fast and potentially scalable\nqubit control. Spin-electric susceptibility, however, renders these qubits\ngenerally vulnerable to electrical noise, which limits their coherence time.\nHere we report on a spin-orbit qubit consisting of a single hole\nelectrostatically confined in a natural silicon metal-oxide-semiconductor\ndevice. By varying the magnetic field orientation, we reveal the existence of\noperation sweet spots where the impact of charge noise is minimized while\npreserving an efficient electric-dipole spin control. We correspondingly\nobserve an extension of the Hahn-echo coherence time up to 88 $\\mu$s, exceeding\nby an order of magnitude the best reported values for hole-spin qubits, and\napproaching the state-of-the-art for electron spin qubits with synthetic\nspin-orbit coupling in isotopically-purified silicon. This finding largely\nenhances the prospects of silicon-based hole spin qubits for scalable quantum\ninformation processing."
    },
    {
        "anchor": "First observation of spin-helical Dirac fermions and topological phases\n  in undoped and doped Bi2Te3 demonstrated by spin-ARPES spectroscopy: Electron systems that possess light-like dispersion relations or the conical\nDirac spectrum, such as graphene and bismuth, have recently been shown to\nharbor unusual collective states in high magnetic fields. Such states are\npossible because their light-like electrons come in spin pairs that are\nchiral,which means that their direction of propagation is tied to a quantity\ncalled pseudospin that describes their location in the crystal lattice. An\nemerging direction in quantum materials research is the manipulation of atomic\nspin-orbit coupling to simulate the effect of a spin dependent magnetic\nfield,in attempt to realize novel spin phases of matter. This effect has been\nproposed to realize systems consisting of unpaired Dirac cones that are\nhelical, meaning their direction of propagation is tied to the electron spin\nitself, which are forbidden to exist in graphene or bismuth. The experimental\nexistence of topological order can not be determined without spin-resolved\nmeasurements. Here we report a spin-and angle-resolved photoemission study of\nthe hexagonal surface of the Bi2Te3 and Bi{2-x}MnxTe3 series, which is found to\nexhibit a single helical Dirac cone that is fully spin-polarized. Our\nobservations of a gap in the bulk spin-degenerate band and a spin-resolved\nsurface Dirac node close to the chemical potential show that the low energy\ndynamics of Bi2Te3 is dominated by the unpaired spin-helical Dirac modes. Our\nspin-texture measurements prove the existence of a rare topological phase in\nthis materials class for the first time, and suggest its suitability for novel\n2D Dirac spin device applications beyond the chiral variety or traditional\ngraphene.",
        "positive": "Conductance Fluctuations and Domain Depinning in Quasi-2D\n  Charge-Density-Wave 1T-TaS$_2$ Thin Films: We investigated the temperature dependence of the conductance fluctuations in\nthin films of the quasi-two-dimensional 1T-TaS$_2$ van der Waals material. The\nconductance fluctuations, determined from the derivative current-voltage\ncharacteristics of two-terminal 1T-TaS$_2$ devices, appear prominently at the\nelectric fields that correspond to the transitions between various\ncharge-density-wave macroscopic quantum condensate phases and at the onset of\nthe depinning of the charge density wave domains. The depinning threshold\nfield, $E_D$, monotonically increases with decreasing temperature within the\nnearly commensurate charge-density-wave phase. The $E_D$ value increases with\nthe decreasing 1T-TaS$_2$ film thickness, revealing the surface pinning of the\ncharge density waves. Our analysis suggests that depinning is absent in the\ncommensurate phase. It is induced by the electric field but facilitated by\nlocal heating. The measured trends for $E_D$ of the domain depinning are\nimportant for understanding the physics of charge density waves in\nquasi-two-dimensional crystals and for developing electronic devices based on\nthis type of quantum materials."
    },
    {
        "anchor": "Electrically driven singlet-triplet transition in triangulene spin-1\n  chains: Recently, graphene triangulene chains have been synthesized and their\nmagnetic response has been analyzed by STM methods by Mishra and coworkers\n(Nature 598, 287 (2021)). Motivated by this study, we determine the exchange\nbilinear and biquadratic constants of the triangulene chains by calculating\ntwo-spin rotations in the spirit of the magnetic force theorem. We then analyze\nopen-ended, odd-numbered chains, whose edge states pair up forming a triplet\nground state. We propose three experimental approaches that enable us to\ntrigger and control a singlet-triplet spin transition. Two of these methods are\nbased on applying a mechanical distortion to the chain. We finally show that\nthe transition can be controlled efficiently by the application of an electric\nfield.",
        "positive": "Spin-orbit interaction in GaAs wells: From one to two subbands: We investigate the Rashba and Dresselhaus spin-orbit (SO) couplings in GaAs\nquantum wells in the range of well widths $w$ allowing for a transition of the\nelectron occupancy from one to two subbands. By performing a detailed\nPoisson-Schr\\\"odinger self-consistent calculation, we determine all the intra-\nand inter-subband Rashba ($\\alpha_1$, $\\alpha_2$, $\\eta$) and Dresselhaus\n($\\beta_1$, $\\beta_2$, $\\Gamma$) coupling strengths. For relatively narrow\nwells with only one subband occupied, our results are consistent with the data\nof Koralek \\emph{et al.} [Nature \\bfs{48}, 610 (2009)], i.e., the Rashba\ncoupling $\\alpha_1$ is essentially independent of $w$ in contrast to the\ndecreasing linear Dresselhaus coefficient $\\beta_1$. When we widen the well so\nthat the second subband can also be populated, we observe that $\\alpha_2$\ndecreases and $\\alpha_1$ increases, both almost linearly with $w$.\nInterestingly, we find that in the parameter range studied (i.e., very\nasymmetric wells) $\\alpha_2$ can attain zero and change its sign, while\n$\\alpha_1$ is always positive. In this double-occupancy regime of $w$'s,\n$\\beta_1$ is mostly constant and $\\beta_2$ decreases with $w$ (similarly to\n$\\beta_1$ for the single-occupancy regime). On the other hand, the intersubband\nRashba coupling strength $\\eta$ decreases with $w$ while the intersubband\nDresselhaus $\\Gamma$ remains almost constant. We also determine the\npersistent-spin-helix symmetry points, at which the Rashba and the renormalized\n(due to cubic corrections) linear Dresselhaus couplings in each subband are\nequal, as a function of the well width and doping asymmetry. Our results should\nstimulate experiments probing SO couplings in multi-subband wells."
    },
    {
        "anchor": "Phase-channel dynamics reveal the role of impurities and screening in a\n  quasi-one-dimensional charge-density wave system: We investigate the low-energy phase excitations of the quasi-one-dimensional\ncharge density wave (CDW) in $\\mathrm{K}_{0.3}\\mathrm{Mo}\\mathrm{O}_3$, by\ndirect probing of infrared-active CDW-lattice modes (phase-phonons) with\nultrafast terahertz spectroscopy. Both the nonequilibrium response and\ntemperature dependence of the bands are reconciled by generalizing the\ntime-dependent Ginzburg-Landau theory, beyond that previously applied to the\namplitude-phonons, to include impurity effects, while the photoinduced\nblue-shifts are attributed to a reduction of the electron-phonon coupling\ninduced by a long-lived free-carrier population.",
        "positive": "Subnanosecond spectral diffusion of a single quantum dot in a nanowire: We have studied spectral diffusion of the photoluminescence of a single CdSe\nquantum dot inserted in a ZnSe nanowire. We have measured the characteristic\ndiffusion time as a function of pumping power and temperature using a recently\ndeveloped technique [G. Sallen et al, Nature Photon. \\textbf{4}, 696 (2010)]\nthat offers subnanosecond resolution. These data are consistent with a model\nwhere only a \\emph{single} carrier wanders around in traps located in the\nvicinity of the quantum dot."
    },
    {
        "anchor": "Phase imaging with intermodulation atomic force microscopy: Intermodulation atomic force microscopy (IMAFM) is a dynamic mode of atomic\nforce microscopy (AFM) with two-tone excitation. The oscillating AFM cantilever\nin close proximity to a surface experiences the nonlinear tip-sample force\nwhich mixes the drive tones and generates new frequency components in the\ncantilever response known as intermodulation products (IMPs). We present a\nprocedure for extracting the phase at each IMP and demonstrate phase images\nmade by recording this phase while scanning. Amplitude and phase images at\nintermodulation frequencies exhibit enhanced topographic and material contrast.",
        "positive": "Topological insulators, spin, and the tight-binding method: As one of the first proposed topologically protected states, the quantum spin\nHall effect in graphene relies critically on the existence of a spin-dependent\ngap at the K/K' points of the Brillouin zone. Using a tight-binding formulation\nbased on the method of invariants, we identify the origin of such an intrinsic\ngap as the three-center interaction between the pi-orbitals caused by\nspin-orbit interactions. This methodology incorporates all symmetry compliant\ninteractions previously neglected and has wider applications for comparisons\nbetween first-principle calculations and the tight-binding method. It also\nidentifies a correction to the Haldane model and its generalization, which\nincorporates the spin degrees of freedom and reproduces all the salient\nfeatures required for the quantum spin Hall effect in graphene."
    },
    {
        "anchor": "Boundary multifractality in critical 1D systems with long-range hopping: Boundary multifractality of electronic wave functions is studied analytically\nand numerically for the power-law random banded matrix (PRBM) model, describing\na critical one-dimensional system with long-range hopping. The peculiarity of\nthe Anderson localization transition in this model is the existence of a line\nof fixed points describing the critical system in the bulk. We demonstrate that\nthe boundary critical theory of the PRBM model is not uniquely determined by\nthe bulk properties. Instead, the boundary criticality is controlled by an\nadditional parameter characterizing the hopping amplitudes of particles\nreflected by the boundary.",
        "positive": "Full Counting Statistics of Cooper Pair Shuttling: The Cooper pair shuttle is a simple model system that combines features of\ncoherent and incoherent transport. We evaluate the full counting statistics\n(FCS) of charge transfer via the shuttle in the incoherent regime. We describe\ntwo limiting cases when the FCS allows for classical interpretation. Generally,\nthe classical interpretation fails yielding negative and imaginary\n\"probabilities\". This signals that superconducting coherence survives even in\nincoherent regime. We evaluate the current noise in some detail."
    },
    {
        "anchor": "High-quality electrical transport using scalable CVD graphene: Producing and manipulating graphene on fab-compatible scale, while\nmaintaining its remarkable carrier mobility, is key to finalize its\ntechnological application. We show that a large-scale approach (chemical vapor\ndeposition on Cu followed by polymer-mediated semi-dry transfer) yields\nsingle-layer graphene crystals fully comparable, in terms of electronic\ntransport, to micro-mechanically exfoliated flakes. hBN is used to encapsulate\nthe graphene crystals $-$ without taking part to their detachment from the\ngrowth catalyst $-$ and study their intrinsic properties in field-effect\ndevices. At room temperature, the electron-phonon coupling sets the mobility to\n$\\sim1.3 \\times10^5$ cm$^2$V$^{-1}$s$^{-1}$ at $\\sim10^{11}$ cm$^{-2}$\nconcentration. At cryogenic temperatures, the mobility ($ > 6\\times10^5$\ncm$^2$V$^{-1}$s$^{-1}$ at $\\sim10^{11}$ cm$^{-2}$) is limited by the devices'\nphysical edges, and charge fluctuations $ < 7\\times10^9$ cm$^{-2}$ are\ndetected. Under perpendicular magnetic fields, we observe early onset of Landau\nquantization ($B\\sim50$ mT) and signatures of electronic correlation, including\nthe fractional quantum Hall effect.",
        "positive": "Partial equilibration of integer and fractional edge channels in the\n  thermal quantum Hall effect: Since the charged mode is much faster than the neutral modes on quantum Hall\nedges at large filling factors, the edge may remain out of equilibrium in\nthermal conductance experiments. This sheds light on the observed imperfect\nquantization of the thermal Hall conductance at $\\nu=8/3$ and can increase the\nobserved thermal conductance by two quanta at $\\nu=8/5$. Under certain unlikely\nbut not impossible assumptions, this might also reconcile the observed thermal\nconductance at $\\nu=5/2$ with not only the PH-Pfaffian order but also the\nanti-Pfaffian order."
    },
    {
        "anchor": "Exchange cotunneling through quantum dots with spin-orbit coupling: We investigate the effects of spin-orbit interaction (SOI) on the exchange\ncotunneling through a spinful Coulomb blockaded quantum dot. In the case of\nzero magnetic field, Kondo effect is shown to take place via a Kramers doublet\nand the SOI will merely affect the Kondo temperature. In contrast, we find that\nthe breaking of time-reversal symmetry in a finite field has a marked influence\non the effective Anderson, and Kondo models for a single level. The nonlinear\nconductance can now be asymmetric in bias voltage and may depend strongly on\ndirection of the magnetic field. A measurement of the angle dependence of\nfinite-field cotunneling spectroscopy thus provides valuable information about\norbital, and spin degrees of freedom and their mutual coupling.",
        "positive": "Measuring Charge Transport in an Amorphous Semiconductor Using Charge\n  Sensing: We measure charge transport in hydrogenated amorphous silicon (a-Si:H) using\na nanometer scale silicon MOSFET as a charge sensor. This charge detection\ntechnique makes possible the measurement of extremely large resistances. At\nhigh temperatures, where the a-Si:H resistance is not too large, the charge\ndetection measurement agrees with a direct measurement of current. The device\ngeometry allows us to probe both the field effect and dispersive transport in\nthe a-Si:H using charge sensing and to extract the density of states near the\nFermi energy."
    },
    {
        "anchor": "Cyclotron spin-flip excitations in a \u03bd=1/3 quantum Hall ferromagnet: Inelastic light scattering spectroscopy around the \\nu=1/3 filling discloses\na novel type of cyclotron spin-flip excitation in a quantum Hall system in\naddition to the excitations previously studied. The excitation energy of the\nobserved mode follows qualitatively the degree of electron spin polarization,\nreaching a maximum value at \\nu=1/3 and thus characterizing it as a \\nu=1/3\nferromagnet eigenmode. Its absolute energy substantially exceeds the\ntheoretical prediction obtained within the renowned single-mode approximation.\nDouble-exciton corrections neglected utilizing the single-mode approach are\nevaluated within the framework of the excitonic representation and are inferred\nto be responsible for the observed effect.",
        "positive": "Laser-induced effects on the electronic features of graphene nanoribbons: We study the interplay between lateral confinement and photon-induced\nprocesses on the electronic properties of illuminated graphene nanoribbons. We\nfind that by tuning the device setup (edges geometries, ribbon width and\npolarization direction), a laser with frequency {\\Omega} may either not affect\nthe electronic structure, or induce bandgaps or depletions at \\hbar {\\Omega}/2,\nand/or at other energies not commensurate with half the photon energy. Similar\nfeatures are also observed in the dc conductance, suggesting the use of the\npolarization direction to switch on and off the graphene device. Our results\ncould guide the design of novel types of optoelectronic nano-devices."
    },
    {
        "anchor": "Heralded spectroscopy reveals exciton-exciton correlations in single\n  colloidal quantum dots: Multiply-excited states in semiconductor quantum dots feature intriguing\nphysics and play a crucial role in nanocrystal-based technologies. While\nphotoluminescence provides a natural probe to investigate these states, room\ntemperature single-particle spectroscopy of their emission has so far proved\nelusive due to the temporal and spectral overlap with emission from the\nsingly-excited and charged states. Here we introduce biexciton heralded\nspectroscopy, enabled by a single-photon avalanche diode array based\nspectrometer. This allows us to directly observe biexciton-exciton emission\ncascades and measure the biexciton binding energy of single quantum dots at\nroom temperature, even though it is well below the scale of thermal broadening\nand spectral diffusion. Furthermore, we uncover correlations hitherto masked in\nensembles, of the biexciton binding energy with both charge-carrier confinement\nand fluctuations of the local electrostatic potential. Heralded spectroscopy\nhas the potential of greatly extending our understanding of charge-carrier\ndynamics in multielectron systems and of parallelization of quantum optics\nprotocols.",
        "positive": "Electronic coherence and coherent dephasing in the optical control of\n  electrons in graphene: Electronic coherence is of utmost importance for the access and control of\nquantum-mechanical solid-state properties. Using a purely electronic\nobservable, the photocurrent, we measure an electronic coherence time of 22 +/-\n4 fs in graphene. The photocurrent is ideally suited to measure electronic\ncoherence as it is a direct result of quantum path interference, controlled by\nthe delay between two ultrashort two-color laser pulses. The maximum delay for\nwhich interference between the population amplitude injected by the first pulse\ninterferes with that generated by the second pulse determines the electronic\ncoherence time. In particular, numerical simulations reveal that the\nexperimental data yield a lower boundary on the electronic coherence time and\nthat coherent dephasing masks a lower coherence time. We expect that our\nresults will significantly advance the understanding of coherent\nquantum-control in solid-state systems ranging from excitation with weak fields\nto strongly driven systems."
    },
    {
        "anchor": "Switching 2D Magnetic States via Pressure Tuning of Layer Stacking: The physical properties of two-dimensional van der Waals (2D vdW) crystals\ndepend sensitively on the interlayer coupling, which is intimately connected to\nthe stacking arrangement and the interlayer spacing. For example, simply\nchanging the twist angle between graphene layers can induce a variety of\ncorrelated electronic phases, which can be controlled further in a continuous\nmanner by applying hydrostatic pressure to decrease the interlayer spacing. In\nthe recently discovered 2D magnets, theory suggests that the interlayer\nexchange coupling strongly depends on layer separation, while the stacking\narrangement can even change the sign of the magnetic exchange, thus drastically\nmodifying the ground state. Here, we demonstrate pressure tuning of magnetic\norder in the 2D magnet CrI3. We probe the magnetic states using tunneling and\nscanning magnetic circular dichroism microscopy measurements. We find that the\ninterlayer magnetic coupling can be more than doubled by hydrostatic pressure.\nIn bilayer CrI3, pressure induces a transition from layered antiferromagnetic\nto ferromagnetic phases. In trilayer CrI3, pressure can create coexisting\ndomains of three phases, one ferromagnetic and two distinct antiferromagnetic.\nThe observed changes in magnetic order can be explained by changes in the\nstacking arrangement. Such coupling between stacking order and magnetism\nprovides ample opportunities for designer magnetic phases and functionalities.",
        "positive": "Spin orbit in curved graphene ribbons: We study the electronic properties of electrons in flat and curved zigzag\ngraphene ribbons using a tight-binding model within the Slater Koster\napproximation.\n  We find that curvature dramatically enhances the action of spin orbit effects\nin graphene ribbons and has a strong effect on the spin orientation of the edge\nstates: whereas spins are normal to the surface in the case of flat ribbons,\nthis is no longer the case in the case of curved ribbons. We find that for the\nedge states, the spin density lies always in the plane perpendicular to the\nribbon axis, and deviate strongly from the normal to the ribbon, even for very\nsmall curvature and the small spin orbit coupling of carbon. We find that\ncurvature results also in an effective second neighbor hopping that modifies\nthe electronic properties of zigzag graphene ribbons. We discuss the\nimplications of our finding in the spin Hall phase of curved graphene Ribbons."
    },
    {
        "anchor": "Improved optomechanical disk resonator sitting on a pedestal mechanical\n  shield: We experimentally demonstrate the controlled enhancement of the mechanical\nquality factor Q of GaAs disk optomechanical resonators. Disks vibrating at 1.3\nGHz with a mechanical shield integrated in their pedestal show a Q improvement\nby a factor 10 to 16. The structure is modeled numerically and different modes\nof vibration are observed, which shed light on the Q enhancement mechanism. An\noptimized double-disk geometry is presented that promises Q above the million\nfor a large parameter range.",
        "positive": "Cavity-photon contribution to the effective interaction of electrons in\n  parallel quantum dots: A single cavity photon mode is expected to modify the Coulomb interaction of\nan electron system in the cavity. Here we investigate this phenomena in a\nparallel double quantum dot system. We explore properties of the closed system\nand the system after it has been opened up for electron transport. We show how\nresults for both cases support the idea that the effective electron-electron\ninteraction becomes more repulsive in the presence of a cavity photon field.\nThis can be understood in terms of the cavity photons dressing the polarization\nterms in the effective mutual electron interaction leading to nontrivial\ndelocalization or polarization of the charge in the double parallel dot\npotential. In addition, we find that the effective repulsion of the electrons\ncan be reduced by quadrupolar collective oscillations excited by an external\nclassical dipole electric field."
    },
    {
        "anchor": "Klein tunneling in graphene: optics with massless electrons: This article provides a pedagogical review on Klein tunneling in graphene,\ni.e. the peculiar tunneling properties of two-dimensional massless Dirac\nelectrons. We consider two simple situations in detail: a massless Dirac\nelectron incident either on a potential step or on a potential barrier and use\nelementary quantum wave mechanics to obtain the transmission probability. We\nemphasize the connection to related phenomena in optics, such as the\nSnell-Descartes law of refraction, total internal reflection, Fabry-P\\'erot\nresonances, negative refraction index materials (the so called meta-materials),\netc. We also stress that Klein tunneling is not a genuine quantum tunneling\neffect as it does not necessarily involve passing through a classically\nforbidden region via evanescent waves. A crucial role in Klein tunneling is\nplayed by the conservation of (sublattice) pseudo-spin, which is discussed in\ndetail. A major consequence is the absence of backscattering at normal\nincidence, of which we give a new shorten proof. The current experimental\nstatus is also thoroughly reviewed. The appendix contains the discussion of a\none-dimensional toy model that clearly illustrates the difference in Klein\ntunneling between mono- and bi-layer graphene.",
        "positive": "Interlayer excitons in MoSe$_2$/WSe$_2$ heterostructures from\n  first-principles: Based on \\emph{ab initio} theoretical calculations of the optical spectra of\nvertical heterostructures of MoSe$_2$ (or MoS$_2$) and WSe$_2$ sheets, we\nreveal two spin-orbit-split Rydberg series of excitonic states below the\n\\textsl{A} excitons of MoSe$_2$ and WSe$_2$ with a significant binding energy\non the order of 250\\,meV for the first excitons in the series. At the same\ntime, we predict crystalographically aligned MoSe$_2$/WSe$_2$ heterostructures\nto exhibit an indirect fundamental band gap. Due to the type-II nature of the\nMoSe$_2$/WSe$_2$ heterostructure, the indirect transition and the exciton\nRydberg series corresponding to a direct transition exhibit a distinct\ninterlayer nature with spatial charge separation of the coupled electrons and\nholes. The experimentally observed long-lived states in photoluminescence\nspectra of MoX$_2$/WY$_2$ heterostructure are attributed to such interlayer\nexciton states. Our calculations further suggest an effect of stacking order on\nthe peak energy of the interlayer excitons and their oscillation strengths."
    },
    {
        "anchor": "Three-dimensional topological photonic crystal with a single surface\n  Dirac cone: A single Dirac cone on the surface is the hallmark of three-dimensional (3D)\ntopological insulators, where the double degeneracy at the Dirac point is\nprotected by time-reversal symmetry and the spin-splitting away from the point\nis provided by the spin-orbital coupling. Here we predict a single Dirac-cone\nsurface state in a 3D photonic crystal, where the degeneracy at the Dirac point\nis protected by a nonsymmorphic glide reflection and the linear splitting away\nfrom it is enabled by breaking time-reversal symmetry. Such a gapless surface\nstate is fully robust against random disorder of any type. This bosonic\ntopological band structure is achieved by applying alternating magnetization to\ngap out the 3D \"generalized Dirac points\" discovered in the bulk of our\ncrystal. The $Z_2$ bulk invariant is characterized through the evolution of\nWannier centers. Our proposal--readily realizable using ferrimagnetic materials\nat microwave frequencies--can also be regarded as the photonic analog of\ntopological crystalline insulators, providing the first 3D bosonic\nsymmetry-protected topological system.",
        "positive": "Spin Response and Collective Modes in Simple Metal Dichalcogenides: Transition metal dichalcogenide (TMD) monolayers are interesting materials in\npart because of their strong spin-orbit coupling. This leads to intrinsic\nspin-splitting of opposite signs in opposite valleys, so the valleys are\nintrinsically spin-polarized when hole-doped. We study spin response in a\nsimple model of these materials, with an eye to identifying sharp collective\nmodes (i.e, spin-waves) that are more commonly characteristic of ferromagnets.\nWe demonstrate that such modes exist for arbitrarily weak repulsive\ninteractions, even when they are too weak to induce spontaneous ferromagnetism.\nThe behavior of the spin response is explored for a range of hole dopings and\ninteraction strengths."
    },
    {
        "anchor": "A single hydrogen molecule as an intensity chopper in an\n  electrically-driven plasmonic nanocavity: Photon statistics is a powerful tool for characterizing the emission dynamics\nof nanoscopic systems and their photophysics. Recent advances that combine\ncorrelation spectroscopy with scanning tunneling microscopy-induced\nluminescence (STML) have allowed measuring the emission dynamics from\nindividual molecules and defects demonstrating their nature as single photon\nemitters. The application of correlation spectroscopy to the analysis of the\ndynamics of a well-characterized adsorbate system in ultrahigh vacuum remained\nto be shown. Here we combine single photon time correlations with STML to\nmeasure the dynamics of individual $H_2$ molecules between a gold tip and a\nAu(111) surface. An adsorbed $H_2$ molecule performs recurrent excursions below\nthe tip apex. We use the fact that the presence of the $H_2$ molecule in the\njunction modifies plasmon emission to study the adsorbate dynamics. Using the\n$H_2$ molecule as a chopper for STM-induced optical emission intensity we\ndemonstrate bunching in the plasmonic photon train in a single measurement over\nsix orders of magnitude in the time domain (from microseconds to seconds) that\ntakes only a few seconds. Our findings illustrate the power of using photon\nstatistics to measure the diffusion dynamics of adsorbates with STML.",
        "positive": "Data mining, dashboard and statistical analysis: a powerful framework\n  for the chemical design of molecular nanomagnets: Three decades of research in molecular nanomagnets have raised their magnetic\nmemories from liquid helium to liquid nitrogen temperature thanks to a wise\nchoice of the magnetic ion and coordination environment. Still, serendipity and\nchemical intuition played a main role. In order to establish a powerful\nframework for statistically driven chemical design, we collected chemical and\nphysical data for lanthanide-based nanomagnets, catalogued over 1400 published\nexperiments, developed an interactive dashboard (SIMDAVIS) to visualise the\ndataset, and applied inferential statistical analysis. Our analysis showed that\nthe Arrhenius energy barrier correlates unexpectedly well with the magnetic\nmemory, as both Orbach and Raman processes can be controlled by vibronic\ncoupling. Indeed, only bis-phthalocyaninato sandwiches and metallocenes, with\nrigid ligands, consistently present magnetic memory up to high temperature.\nAnalysing magnetostructural correlations, we offer promising strategies for\nimprovement, in particular for the preparation of pentagonal bipyramids, where\neven \"softer\" complexes are protected against molecular vibrations."
    },
    {
        "anchor": "Cavity control of Excitons in two dimensional Materials: We propose a robust and efficient way of controlling the optical spectra of\ntwo-dimensional materials and van der Waals heterostructures by quantum cavity\nembedding. The cavity light-matter coupling leads to the formation of\nexciton-polaritons, a superposition of photons and excitons. Our first\nprinciples study demonstrates a reordering and mixing of bright and dark\nexcitons spectral features and in the case of a type II van-der-Waals\nheterostructure an inversion of intra and interlayer excitonic resonances. We\nfurther show that the cavity light-matter coupling strongly depends on the\ndielectric environment and can be controlled by encapsulating the active 2D\ncrystal in another dielectric material. Our theoretical calculations are based\non a newly developed non-perturbative many-body framework to solve the coupled\nelectron-photon Schr\\\"odinger equation in a quantum-electrodynamical extension\nof the Bethe-Salpeter approach. This approach enables the ab-initio simulations\nof exciton-polariton states and their dispersion from weak to strong cavity\nlight-matter coupling regimes. Our method is then extended to treat van der\nWaals heterostructures and encapsulated 2D materials using a simplified\nMott-Wannier description of the excitons that can be applied to very large\nsystems beyond reach for fully ab-initio approaches.",
        "positive": "Magnetic properties of graphene quantum dots: Using the tight-binding approximation we calculated the magnetic\nsusceptibility of graphene quantum dots (GQD) of different geometrical shapes\nand sizes, smaller than the magnetic length, when the magnetic properties are\ngoverned by the electron edge states. Two types of edge states can be\ndiscerned: the zero-energy states (ZES) located exactly at the zero-energy\nDirac point, and the dispersed edge states (DES) with the energy close, but not\nexactly equal to zero. DES are responsible for the temperature independent\ndiamagnetic response, while ZES provide the temperature dependent spin Curie\nparamagnetism. The hexagonal, circular and randomly shaped GQDs contain mainly\nDES and, as a result, they are diamagnetic. The edge states of the triangular\nGQDs are ZES and these dots reveal the interplay between the spin\nparamagnetism, dominating for small dots and at low temperatures, and bulk\norbital diamagnetism, dominating for large dots and at high temperatures."
    },
    {
        "anchor": "Non-Hermitian physics without gain or loss: the skin effect of reflected\n  waves: Physically, one tends to think of non-Hermitian systems in terms of gain and\nloss: the decay or amplification of a mode is given by the imaginary part of\nits energy. Here, we introduce an alternative avenue to the realm of\nnon-Hermitian physics, which involves neither gain nor loss. Instead, complex\neigenvalues emerge from the amplitudes and phase-differences of waves\nbackscattered from the boundary of insulators. We show that for any strong\ntopological insulator in a Wigner-Dyson class, the reflected waves are\ncharacterized by a reflection matrix exhibiting the non-Hermitian skin effect.\nThis leads to an unconventional Goos-H\\\"{a}nchen effect: due to non-Hermitian\ntopology, waves undergo a lateral shift upon reflection, even at normal\nincidence. Going beyond systems with gain and loss vastly expands the set of\nexperimental platforms that can access non-Hermitian physics and show\nsignatures associated to non-Hermitian topology.",
        "positive": "Non-adiabatic exciton-phonon coupling in Raman spectroscopy of layered\n  materials: We present an ab initio computational approach for the calculation of\nresonant Raman intensities, including both excitonic and non-adiabatic effects.\nOur diagrammatic approach, which we apply to two prototype, semiconducting\nlayered materials, allows a detailed analysis of the impact of phonon-mediated\nexciton-exciton scattering on the intensities. In the case of bulk hexagonal\nboron nitride, this scattering leads to strong quantum interference between\ndifferent excitonic resonances, strongly redistributing oscillator strength\nwith respect to optical absorption spectra. In the case of MoS$_2$, we observe\nthat quantum interference effects are suppressed by the spin-orbit splitting of\nthe excitons."
    },
    {
        "anchor": "Coherent magnetotransport spectroscopy in an edge-blocked double quantum\n  wire with window and resonator coupling: We propose an electronic double quantum wire system that contains a pair of\nedge blocking potential and a coupling element in the middle barrier between\ntwo ballistic quantum wires. A window and a resonator coupling control between\nthe parallel wires are discussed and compared for the enhancement of the\ninterwire transfer processes in an appropriate magnetic field. We illustrate\nthe results of the analysis by performing computational simulations on the\nconductance and probability density of electron waves in the window and\nresonator coupled double wire system.",
        "positive": "Role of Anisotropy in Nonlinear Harmonic Generation Across TMD\n  Monolayers: Recent techniques have allowed transition metal dichalcogenides (TMD)\nmonolayers to be grown and adequately characterised. Of particular interest,\ntheir nonlinear optical response presents many promising opportunities for\nfuture nanophotonic devices and technology. The dispersion of the carriers is\ntrigonally-warped, leading to an anisotropic Fermi surface for low-lying\nstates. In this paper, the effects of such a deformation on the nonlinear\nharmonic generation are studied by considering a tight-binding model expanded\nup to third order in $\\mathbf{k} \\cdot \\mathbf{p}$. By solving exactly the\nfree-carrier dynamics of the carriers when interacting with intense and\nultrashort pulses of light, we predict the photogenerated current in a\nnonperturbative way and study its harmonic composition. We find frequency and\namplitude modulation of the nonlinear current in quadratic and cubic models.\nFurthermore, we demonstrate anisotropy-induced modulation of the intensity of\nhigher-order harmonics and the existence of harmonic crossovers, depending on\nthe incident light polarisation. The methodology presented in this paper may be\napplied to any general effective two-band model and offer a pathway to identify\nsignatures of electronic features in optical output."
    },
    {
        "anchor": "Disorder-driven splitting of the conductance peak at the Dirac point in\n  graphene: The electronic properties of a bricklayer model, which shares the same\ntopology as the hexagonal lattice of graphene, are investigated numerically. We\nstudy the influence of random magnetic-field disorder in addition to a strong\nperpendicular magnetic field. We found a disorder-driven splitting of the\nlongitudinal conductance peak within the narrow lowest Landau band near the\nDirac point. The energy splitting follows a relation which is proportional to\nthe square root of the magnetic field and linear in the disorder strength. We\ncalculate the scale invariant peaks of the two-terminal conductance and obtain\nthe critical exponents as well as the multifractal properties of the chiral and\nquantum Hall states. We found approximate values $\\nu\\approx 2.5$ for the\nquantum Hall states, but $\\nu=0.33\\pm 0.1$ for the divergence of the\ncorrelation length of the chiral state at E=0 in the presence of a strong\nmagnetic field. Within the central $n=0$ Landau band, the multifractal\nproperties of both the chiral and the split quantum Hall states are the same,\nshowing a parabolic $f[\\alpha(s)]$ distribution with $\\alpha(0)=2.27\\pm 0.02$.\nIn the absence of the constant magnetic field, the chiral critical state is\ndetermined by $\\alpha(0)=2.14\\pm 0.02$.",
        "positive": "Berry curvature induced giant intrinsic spin-orbit torque in single\n  layer magnetic Weyl semimetal thin films: Topological quantum materials can exhibit unconventional surface states and\nanomalous transport properties, but their applications to spintronic devices\nare restricted as they require the growth of high-quality thin films with\nbulk-like properties. Here, we study 10--30 nm thick epitaxial ferromagnetic\nCo$_{\\rm 2}$MnGa films with high structural order. Very high values of the\nanomalous Hall conductivity, $\\sigma_{\\rm xy}=1.35\\times10^{5}$ $\\Omega^{-1}\nm^{-1}$, and the anomalous Hall angle, $\\theta_{\\rm H}=15.8\\%$, both comparable\nto bulk values. We observe a dramatic crystalline orientation dependence of the\nGilbert damping constant of a factor of two and a giant intrinsic spin Hall\nconductivity, $\\mathit{\\sigma_{\\rm SHC}}=(6.08\\pm 0.02)\\times 10^{5}$\n($\\hbar/2e$) $\\Omega^{-1} m^{-1}$, which is an order of magnitude higher than\nliterature values of single-layer Ni$_{\\rm 80}$Fe$_{\\rm 20}$, Ni, Co, Fe, and\nmultilayer Co$_{\\rm 2}$MnGa stacks. Theoretical calculations of the intrinsic\nspin Hall conductivity, originating from a strong Berry curvature, corroborate\nthe results and yield values comparable to the experiment. Our results open up\nfor the design of spintronic devices based on single layers of topological\nquantum materials."
    },
    {
        "anchor": "Measurement of Topological Berry Phase in Highly Disordered Graphene: We have observed the quantum Hall effect (QHE) and Shubnikov-de Haas (SdH)\noscillations in highly disordered graphene at magnetic fields up to 65 T.\nDisorder was introduced by hydrogenation of graphene up to a ratio H/C $\\approx\n0.1\\%$. The analysis of SdH oscillations and QHE indicates that the topological\npart of the Berry phase, proportional to the pseudo-spin winding number, is\nrobust against introduction of disorder by hydrogenation in large scale\ngraphene.",
        "positive": "Coherent spin rotations in open driven double quantum dots: We analyze the charge and spin dynamics in a DC biased double quantum dot\ndriven by crossed DC and AC magnetic fields. In this configuration, spatial\ndelocalization due to inter-dot tunnel competes with intra-dot spin rotations\ninduced by the time dependent magnetic field, giving rise to a complicated time\ndependent behavior of the tunnelling current. When the Zeeman splitting has the\nsame value in both dots and spin flip is negligible, the electrons remain in\nthe triplet subspace (dark subspace) performing coherent spin rotations and the\ncurrent does not flow. This electronic trapping is removed either by finite\nspin relaxation or when the Zeeman splitting is different in each quantum dot.\nIn the first case, our results show that measuring the current will allow to\nget information on the spin relaxation time. In the last case, we will show\nthat applying a resonant bichromatic magnetic field, the electrons become\ntrapped in a coherent superposition of states and electronic transport is\nblocked. Then, manipulating AC magnetic fields, electrons are driven to perform\ncoherent spin rotations which can be unambiguously detected by direct\nmeasurement of the tunneling current."
    },
    {
        "anchor": "Dielectric screening in two-dimensional insulators: Implications for\n  excitonic and impurity states in graphane: For atomic thin layer insulating materials we provide an exact analytic form\nof the two-dimensional screened potential. In contrast to three-dimensional\nsystems where the macroscopic screening can be described by a static dielectric\nconstant in 2D systems the macroscopic screening is non local (q-dependent)\nshowing a logarithmic divergence for small distances and reaching the\nunscreened Coulomb potential for large distances. The cross-over of these two\nregimes is dictated by 2D layer polarizability that can be easily computed by\nstandard first-principles techniques. The present results have strong\nimplications for describing gap-impurity levels and also exciton binding\nenergies. The simple model derived here captures the main physical effects and\nreproduces well, for the case of graphane, the full many-body GW plus\nBethe-Salpeter calculations. As an additional outcome we show that the impurity\nhole-doping in graphane leads to strongly localized states, what hampers\napplications in electronic devices. In spite of the inefficient and nonlocal\ntwo-dimensional macroscopic screening we demonstrate that a simple\n$\\mathbf{k}\\cdot\\mathbf{p}$ approach is capable to describe the electronic and\ntransport properties of confined 2D systems.",
        "positive": "Charge transport in a multi-terminal DNA tetrahedron: Interplay among\n  contact position, disorder, and base-pair mismatch: As a secondary structure of DNA, DNA tetrahedra exhibit intriguing charge\ntransport phenomena and provide a promising platform for wide applications like\nbiosensors, as shown in recent electrochemical experiments. Here, we study\ncharge transport in a multi-terminal DNA tetrahedron, finding that its charge\ntransport properties strongly depend upon the interplay among contact position,\non-site energy disorder, and base-pair mismatch. Our results indicate that the\ncharge transport efficiency is nearly independent of contact position in the\nweak disorder regime, and is dramatically declined by the occurrence of a\nsingle base-pair mismatch between the source and the drain, in accordance with\nexperimental results [J. Am. Chem. Soc. {\\bf 134}, 13148 (2012); Chem. Sci.\n{\\bf 9}, 979 (2018)]. By contrast, the charge transport efficiency could be\nenhanced monotonically by shifting the source toward the drain in the strong\ndisorder regime, and be increased when the base-pair mismatch takes place\nexactly at the contact position. In particular, when the source moves\nsuccessively from the top vertex to the drain, the charge transport through the\ntetrahedral DNA device can be separated into three regimes, ranging from\ndisorder-induced linear decrement of charge transport to disorder-insensitive\ncharge transport, and to disorder-enhanced charge transport. Finally, we\npredict that the DNA tetrahedron functions as a more efficient spin filter\ncompared to double-stranded DNA and opposite spin polarization could be\nobserved at different drains, which may be used to separate spin-unpolarized\nelectrons into spin-up ones and spin-down ones. These results could be readily\nchecked by electrochemical measurements and may help for designing novel DNA\ntetrahedron-based molecular nanodevices."
    },
    {
        "anchor": "Variation of elastic scattering across a quantum well: The Drude scattering times of electrons in two subbands of a parabolic\nquantum well have been studied at constant electron sheet density and different\npositions of the electron distribution along the growth direction. The\nscattering times obtained by magnetotransport measurements decrease as the\nelectrons are displaced towards the well edges, although the lowest-subband\ndensity increases. By comparing the measurements with calculations of the\nscattering times of a two-subband system, new information on the location of\nthe relevant scatterers and the anisotropy of intersubband scattering is\nobtained. It is found that the scattering time of electrons in the lower\nsubband depends sensitively on the position of the scatterers, which also\nexplains the measured dependence of the scattering on the carrier density. The\nmeasurements indicate segregation of scatterers from the substrate side towards\nthe quantum well during growth.",
        "positive": "Stable antiferromagnetic graphone: Density functional modeling of atomic structure and calculation of electronic\nstructure of one-side one-sublattice functionalized graphene (graphone) are\nperformed for hydrogen and fluorine adatoms. Shown that using of fluorine for\nfunctionalization not on enhance stability of compound but also provide switch\nof magnetic ground state from ferro- to antiferromagnetic. Half-metallic\nferromagnetic state in fluorine based graphone is also discussed."
    },
    {
        "anchor": "Energy loss of the electron system in individual single-walled carbon\n  nanotubes: We characterize the energy loss of the non-equilibrium electron system in\nindividual metallic single-walled carbon nanotubes at low temperature. Using\nJohnson noise thermometry, we demonstrate that, for a nanotube with ohmic\ncontacts, the dc resistance at finite bias current directly reflects the\naverage electron temperature. This enables a straightforward determination of\nthe thermal conductance associated with cooling of the nanotube electron\nsystem. In analyzing the temperature- and length-dependence of the thermal\nconductance, we consider contributions from acoustic phonon emission, optical\nphonon emission, and hot electron outdiffusion.",
        "positive": "Spin noise of localized electrons: Interplay of hopping and hyperfine\n  interaction: The theory of spin fluctuations is developed for an ensemble of localized\nelectrons taking into account both hyperfine interaction of electron and\nnuclear spins and electron hopping between the sites. The analytical expression\nfor the spin noise spectrum is derived for arbitrary relation between the\nelectron spin precession frequency in the field of the nuclear fluctuation and\nthe hopping rate. An increase in the hopping rate results in the drastic change\nof the spin noise spectrum. The effect of an external magnetic field is briefly\naddressed."
    },
    {
        "anchor": "Quantum entanglement in soliton fractionalisation process: Quantum state, in relativistic quantum mechanics, itself turns out to be an\nentangled state due to its own degrees freedom such as spin and momentum. This\npeculiar entanglement leaves the transformed state mixed. We consider the\nfractional charge state that arises in a theory of fermion interacting with\nscalar background in this context. The apparent entanglement occurs between\nfermion ans scalar through Yukawa-type interaction. However, the spontaneous\nsymmetry breaking causes appearance of the $c$-number zero energy solution of\nthe Dirac equation as a pure state. Quantum entanglement in such relativistic\nsystem is proposed to have a microscopic view of the spontaneous symmetry\nbreaking which has been realised in condensed matter system like polyacetylene.",
        "positive": "Tunable Ultrafast Thermal Relaxation in Graphene Measured by\n  Continuous-Wave Photomixing: Hot electron effects in graphene are significant because of graphene's small\nelectronic heat capacity and weak electron-phonon coupling, yet the dynamics\nand cooling mechanisms of hot electrons in graphene are not completely\nunderstood. We describe a novel photocurrent spectroscopy method that uses the\nmixing of continuous-wave lasers in a graphene photothermal detector to measure\nthe frequency dependence and nonlinearity of hot-electron cooling in graphene\nas a function of the carrier concentration and temperature. The method offers\nunparalleled sensitivity to the nonlinearity, and probes the ultrafast cooling\nof hot carriers with an optical fluence that is orders of magnitude smaller\nthan in conventional time-domain methods, allowing for accurate\ncharacterization of electron-phonon cooling near charge neutrality. Our\nmeasurements reveal that near the charge neutral-point the nonlinear power\ndependence of the electron cooling is dominated by disorder-assisted\ncollisions, while at higher carrier concentrations conventional\nmomentum-conserving cooling prevails in the nonlinear dependence. The relative\ncontribution of these competing mechanisms can be electrostatically tuned\nthrough the application of a gate voltage -- an effect that is unique to\ngraphene."
    },
    {
        "anchor": "Infrared Spectroscopy of Wafer-Scale Graphene: We report on spectroscopy results from the mid- to far-infrared on\nwafer-scale graphene, grown either epitaxially on silicon carbide, or by\nchemical vapor deposition. The free carrier absorption (Drude peak) is\nsimultaneously obtained with the universal optical conductivity (due to\ninterband transitions), and the wavelength at which Pauli blocking occurs due\nto band filling. From these the graphene layer number, doping level, sheet\nresistivity, carrier mobility, and scattering rate can be inferred. The mid-IR\nabsorption of epitaxial two-layer graphene shows a less pronounced peak at\n0.37\\pm0.02 eV compared to that in exfoliated bilayer graphene. In heavily\nchemically-doped single layer graphene, a record high transmission reduction\ndue to free carriers approaching 40% at 250 \\mum (40 cm-1) is measured in this\natomically thin material, supporting the great potential of graphene in\nfar-infrared and terahertz optoelectronics.",
        "positive": "Diffusion-induced dissipation and mode coupling in nanomechanical\n  resonators: We study a system consisting of a particle adsorbed on a carbon nanotube\nresonator. The particle is allowed to diffuse along the resonator, in order to\nenable study of e.g. room temperature mass sensing devices. The system is\ninitialized in a state where only the fundamental vibration mode is excited,\nand the ring-down of the system is studied by numerically and analytically\nsolving the stochastic equations of motion. We find two mechanisms of\ndissipation, induced by the diffusing adsorbate. First, short-time correlations\nbetween particle and resonator motions means that the net effect of the former\non the latter does not average out, but instead causes dissipation of\nvibrational energy. For vibrational amplitudes that are much larger than the\nthermal energy this dissipation is linear; for small amplitudes the decay takes\nthe same form as that of a nonlinearly damped oscillator. Second, the particle\ndiffusion mediates a coupling between vibration modes, enabling energy transfer\nfrom the fundamental mode to excited modes, which rapidly reach thermal\nequilibrium."
    },
    {
        "anchor": "Nano-to-micro spatiotemporal imaging of magnetic skyrmion's life cycle: Magnetic skyrmions are the self-organized topological spin textures behaving\nlike particles. Because of their fast creation and typically long lifetime,\nexperimental verification of skyrmion's creation/annihilation processes has\nbeen challenging. Here we successfully track skyrmions dynamics in\ndefect-introduced Co9Zn9Mn2, by using pump-probe Lorentz transmission electron\nmicroscope. Following the nanosecond-photothermal excitation, we resolve\n160-nm-skyrmion's proliferation at <1 ns, contraction at 5 ns, drift from 10 ns\nto 4 microsecond and coalescence at 5 microsecond. These motions relay the\nmultiscale arrangement and relaxation of skyrmion clusters in a repeatable\ncycle of 20 kHz. Such repeatable dynamics of skyrmions, arising from the\nweakened but still persistent topological protection around defects, enables us\nto visualize the whole life of the skyrmions, as well as demonstrating the\npossible high-frequency manipulations of topological charges brought by\nskyrmions.",
        "positive": "Skyrmions Driven by Intrinsic Magnons: We study the dynamics of a skyrmion in a magnetic insulating nanowire in the\npresence of time-dependent oscillating magnetic field gradients. These ac\nfields act as a net driving force on the skyrmion via its own intrinsic\nmagnetic excitations. In a microscopic quantum field theory approach we include\nthe unavoidable coupling of the external field to the magnons, which gives rise\nto time-dependent dissipation for the skyrmion. We demonstrate that the\nmagnetic ac field induces a super-Ohmic to Ohmic crossover behavior for the\nskyrmion dissipation kernels with time-dependent Ohmic terms. The ac driving of\nthe magnon bath at resonance results in a unidirectional helical propagation of\nthe skyrmion in addition to the otherwise periodic bounded motion."
    },
    {
        "anchor": "Seebeck power generation and Peltier cooling in a Normal metal-quantum\n  dot-superconductor nanodevice: We theoretically investigate the Seebeck and Peltier effect across an\ninteracting quantum dot(QD) coupled between a normal metal and a\nBardeen-Cooper-Schrieffer superconductor within the Coulomb blockade regime.\nOur results demonstrate that the thermoelectric conversion efficiency at\noptimal power output (optimized with respect to QD energy level and external\nserial load) in NQDS nanodevice can reach up to $58\\%\\eta_C$, where $\\eta_C$ is\nCarnot efficiency, with output power $P_{max}\\approx 35fW$ for temperature\nbelow the superconducting transition temperature. Further, the Peltier cooling\neffect is observed for a wide range of parameter regimes, which can be\noptimized by varying the background thermal energy, QD level energy,\nQD-reservoir tunneling strength, and bias voltage. The results presented in\nthis study are within the scope of existing experimental capabilities for\ndesigning miniature hybrid devices that operate at cryogenic temperatures.",
        "positive": "Coherent coupling of a single spin to microwave cavity photons: Electron spins and photons are complementary quantum-mechanical objects that\ncan be used to carry, manipulate and transform quantum information. To combine\nthese resources, it is desirable to achieve the coherent coupling of a single\nspin to photons stored in a superconducting resonator. Using a circuit design\nbased on a nanoscale spin-valve, we coherently hybridize the individual spin\nand charge states of a double quantum dot while preserving spin coherence. This\nscheme allows us to achieve spin-photon coupling up to the MHz range at the\nsingle spin level. The cooperativity is found to reach 2.3, and the spin\ncoherence time is about 60ns. We thereby demonstrate a mesoscopic device\nsuitable for non-destructive spin read-out and distant spin coupling."
    },
    {
        "anchor": "Field Effect Transistors for Terahertz Detection: Physics and First\n  Imaging Applications: Resonant frequencies of the two-dimensional plasma in FETs increase with the\nreduction of the channel dimensions and can reach the THz range for sub-micron\ngate lengths. Nonlinear properties of the electron plasma in the transistor\nchannel can be used for the detection and mixing of THz frequencies. At\ncryogenic temperatures resonant and gate voltage tunable detection related to\nplasma waves resonances, is observed. At room temperature, when plasma\noscillations are overdamped, the FET can operate as an efficient broadband THz\ndetector. We present the main theoretical and experimental results on THz\ndetection by FETs in the context of their possible application for THz imaging.",
        "positive": "Majorana bound states in encapsulated bilayer graphene: The search for robust topological superconductivity and Majorana bound states\ncontinues, exploring both one-dimensional (1D) systems such as semiconducting\nnanowires and two-dimensional (2D) platforms. In this work we study a 2D\napproach based on graphene bilayers encapsulated in transition metal\ndichalcogenides that, unlike previous proposals involving the Quantum Hall\nregime in graphene, requires weaker magnetic fields and does not rely on\ninteractions. The encapsulation induces strong spin-orbit coupling on the\ngraphene bilayer, which opens a sizeable gap and stabilizes fragile pairs of\nhelical edge states. We show that, when subject to an in-plane Zeeman field,\narmchair edges can be transformed into p-wave one-dimensional topological\nsuperconductors by contacting them laterally with conventional superconductors.\nWe demonstrate the emergence of Majorana bound states (MBSs) at the sample\ncorners of crystallographically perfect flakes, belonging either to the D or\nthe BDI symmetry classes depending on parameters. We compute the phase diagram,\nthe resilience of MBSs against imperfections, and their manifestation as a\n4$\\pi$-periodic effect in Josephson junction geometries, all suggesting the\nexistence of a topological phase within experimental reach."
    },
    {
        "anchor": "Electronic and magneto-optical properties of monolayer phosphorene\n  quantum dots: We theoretically investigate the electronic and magneto-optical properties of\nrectangular, hexangular, and triangular monolayer phosphorene quantum dots\n(MPQDs) utilizing the tight-binding method. The electronic states, density of\nstates, electronic density distribution, and Laudau levels as well as the\noptical absorption spectrum are calculated numerically. Our calculations show\nthat: (1) edge states appear in the band gap in all kinds of MPQDs regardless\nof their shapes and edge configurations due to the anisotropic electron hopping\nin monolayer phosphorene (MLP). Electrons in any edge state appear only in the\narmchair direction of the dot boundary, which is distinct from that in graphene\nquantum dots; (2) the magnetic levels of MPQDs exhibit a Hofstadter-butterfly\nspectrum and approach the Landau levels of MLP as the magnetic field increases\n. A \"flat band\" appears in the magneto-energy spectrum which is totally\ndifferent from that of MLP; (3) the electronic and optical properties can be\ntuned by the dot size, the types of boundary edges and the external magnetic\nfield.",
        "positive": "Quantum pumping in a ballistic graphene bilayer: We investigate quantum pumping of massless Dirac fermions in an ideal\n(impurity free) double layer of graphene. The pumped current is generated by\nadiabatic variation of two gate voltages in the contact regions to a weakly\ndoped double graphene sheet. At the Dirac point and for a wide bilayer with\nwidth W much larger then length L, we find that the pumped current scales\nlinearly with the interlayer coupling length l_{perp} for L/l_{perp} << 1, is\nmaximal for L/l_{perp} ~ 1, and crosses over to a\nlog(L/l_{perp})/(L/l_{perp})-dependence for L/l_{perp} >> 1. We compare our\nresults with the behavior of the conductance in the same system and discuss\ntheir experimental feasibility."
    },
    {
        "anchor": "Noiseless nonreciprocity in a parametric active device: Nonreciprocal devices such as circulators and isolators belong to an\nimportant class of microwave components employed in applications like the\nmeasurement of mesoscopic circuits at cryogenic temperatures. The measurement\nprotocols usually involve an amplification chain which relies on circulators to\nseparate input and output channels and to suppress backaction from different\nstages on the sample under test. In these devices the usual reciprocal symmetry\nof circuits is broken by the phenomenon of Faraday rotation based on magnetic\nmaterials and fields. However, magnets are averse to on-chip integration, and\nmagnetic fields are deleterious to delicate superconducting devices. Here we\npresent a new proposal combining two stages of parametric modulation emulating\nthe action of a circulator. It is devoid of magnetic components and suitable\nfor on-chip integration. As the design is free of any dissipative elements and\nbased on reversible operation, the device operates noiselessly, giving it an\nimportant advantage over other nonreciprocal active devices for quantum\ninformation processing applications.",
        "positive": "Engineering of anomalous Josephson effect in coherently coupled\n  Josephson junctions: A Josephson junction (JJ) is a key device in the development of\nsuperconducting circuits, wherein a supercurrent in the JJ is controlled by the\nphase difference between the two superconducting electrodes. Recently, it has\nbeen shown that the JJ current is nonlocally controlled by the phase difference\nof another nearby JJ via coherent coupling. Here, we use the nonlocal control\nto engineer the anomalous Josephson effect. We observe that a supercurrent is\nproduced by the nonlocal phase control even without any local phase difference,\nusing a quantum interference device. The nonlocal phase control simultaneously\ngenerates an offset of a local phase difference giving the JJ ground state.\nThese results provide novel concepts for engineering superconducting devices\nsuch as phase batteries and dissipationless rectifiers."
    },
    {
        "anchor": "Quantum phase transition in a non-Hermitian XY spin chain with global\n  complex transverse field: In this work, we investigate the quantum phase transition in a non-Hermitian\nXY spin chain. The phase diagram shows that the critical points of Ising phase\ntransition expand into a critical transition zone after introducing a\nnon-Hermitian effect. By analyzing the non-Hermitian gap and long-range\ncorrelation function, one can distinguish different phases by means of\ndifferent gap features and decay properties of correlation function, a tricky\nproblem in traditional XY model. Furthermore, the results reveal the\nrelationship among different regions of the phase diagram, non-Hermitian energy\ngap and long-range correlation function.",
        "positive": "The role of first neighbors geometry in the electronic and mechanical\n  properties of atomic contacts: We study in detail, by experimental measurements, atomistic simulations and\nDFT transport calculations, the process of formation and the resulting\nelectronic properties of atomic-sized contacts made of Au, Ag and Cu. Our novel\napproaches to the data analysis of both experimental results and simulations,\nlead to a precise relationship between geometry and electronic transmission. We\nreestablish the significant influence of the number of first neighbors on the\nelectronic properties of atomic-sized contacts. Our results allow us also to\ninterpret subtle differences between the metals during the process of contact\nformation as well as the characteristics of the resulting contacts."
    },
    {
        "anchor": "Exploring a proximity-coupled Co chain on Pb(110) as a possible Majorana\n  platform: Linear, suspended chains of magnetic atoms proximity coupled to an s-wave\nsuperconductor are predicted to host Majorana zero modes at the chain ends in\nthe presence of strong spin-orbit coupling. Specifically, iron (Fe) chains on\nPb(110) have been explored as a possible system to exhibit topological\nsuperconductivity and host Majorana zero-modes [Nadj-Perge, et al., Science\n346, 602 (2014)]. Here, we study chains of the transition metal cobalt (Co) on\nPb(110) and check for topological signatures. Using spin-polarized scanning\ntunneling spectroscopy, we resolve ferromagnetic order in the $d$ bands of the\nchains. Interestingly, also the subgap Yu-Shiba-Rusinov (YSR) bands carry a\nspin polarization as was predicted decades ago. Superconducting tips allow us\nto resolve further details of the YSR bands and in particular resonances at\nzero energy. We map the spatial distribution of the zero-energy signal and find\nit delocalized along the chain. Hence, despite of the ferromagnetic coupling\nwithin the chains and the strong-spin orbit coupling in the superconductor, we\ndo not find clear evidence of Majorana modes. Simple tight-binding calculations\nsuggest that the spin-orbit-split bands may cross the Fermi level four times\nwhich suppresses the zero-energy modes.",
        "positive": "Coupling Remote States through the Continuum: Multi-State Fano\n  Resonances: We demonstrate a fully-tunable multi-state Fano system in which\nremotely-implemented quantum states interfere with each other through their\ncoupling to a mutual continuum. On tuning these resonances near coincidence a\nrobust avoided crossing is observed, with a distinctive character that confirms\nthe continuum as the source of the coupling. While the continuum often serves\nas a source of decoherence, our work therefore shows how its presence can\ninstead also be essential to mediate the interaction of quantum states, a\nresult that could allow new approaches to engineer the collective states of\nnanostructures."
    },
    {
        "anchor": "Non-adiabatic two-parameter charge and spin pumping in a quantum dot: We study DC charge and spin transport through a weakly coupled quantum dot,\ndriven by a non-adiabatic periodic change of system parameters. We generalize\nthe model of Tien and Gordon to simultaneously oscillating voltages and tunnel\ncouplings. When applying our general result to the two-parameter charge pumping\nin quantum dots, we find interference effects between the oscillations of the\nvoltage and tunnel couplings. Furthermore, we discuss the possibility to\nelectrically pump a spin current in presence of a static magnetic field.",
        "positive": "Microwave Transport in Metallic Single-Walled Carbon Nanotubes: The dynamical conductance of electrically contacted single-walled carbon\nnanotubes is measured from dc to 10 GHz as a function of source-drain voltage\nin both the low-field and high-field limits. The ac conductance of the nanotube\nitself is found to be equal to the dc conductance over the frequency range\nstudied for tubes in both the ballistic and diffusive limit. This clearly\ndemonstrates that nanotubes can carry high-frequency currents at least as well\nas dc currents over a wide range of operating conditions. Although a detailed\ntheoretical explanation is still lacking, we present a phenomenological model\nof the ac impedance of a carbon nanotube in the presence of scattering that is\nconsistent with these results."
    },
    {
        "anchor": "Fast coherent manipulation of three-electron states in a double quantum\n  dot: A fundamental goal in the manipulation of quantum systems is the achievement\nof many coherent oscillations within the characteristic dephasing time T2*[1].\nMost manipulations of electron spins in quantum dots have focused on the\nconstruction and control of two-state quantum systems, or qubits, in which each\nquantum dot is occupied by a single electron[2-7]. Here we perform quantum\nmanipulations on a system with more electrons per quantum dot, in a double dot\nwith three electrons. We demonstrate that tailored pulse sequences can be used\nto induce coherent rotations between 3-electron quantum states. Certain pulse\nsequences yield coherent oscillations with a very high figure of merit (the\nratio of coherence time to rotation time) of >100. The presence of the third\nelectron enables very fast rotations to all possible states, in contrast to the\ncase when only two electrons are used, in which some rotations are slow. The\nminimum oscillation frequency we observe is >5 GHz.",
        "positive": "The Fermi edge singularity of spin polarized electrons: We study the absorption spectrum of a two-dimensional electron gas (2DEG) in\na magnetic field. We find that that at low temperatures, when the 2DEG is spin\npolarized, the absorption spectra, which correspond to the creation of spin up\nor spin down electron, differ in magnitude, linewidth and filling factor\ndependence. We show that these differences can be explained as resulting from\ncreation of a Mahan exciton in one case, and of a power law Fermi edge\nsingularity in the other."
    },
    {
        "anchor": "Measurement of Rashba and Dresselhaus spin-orbit magnetic fields: Spin-orbit coupling is a manifestation of special relativity. In the\nreference frame of a moving electron, electric fields transform into magnetic\nfields, which interact with the electron spin and lift the degeneracy of\nspin-up and spin-down states. In solid-state systems, the resulting spin-orbit\nfields are referred to as Dresselhaus or Rashba fields, depending on whether\nthe electric fields originate from bulk or structure inversion asymmetry,\nrespectively. Yet, it remains a challenge to determine the absolute value of\nboth contributions in a single sample. Here we show that both fields can be\nmeasured by optically monitoring the angular dependence of the electrons' spin\nprecession on their direction of movement with respect to the crystal lattice.\nFurthermore, we demonstrate spin resonance induced by the spin-orbit fields. We\napply our method to GaAs/InGaAs quantum-well electrons, but it can be used\nuniversally to characterise spin-orbit interactions in semiconductors,\nfacilitating the design of spintronic devices.",
        "positive": "Multi-particle correlations of an oscillating scatterer: Using multi-particle distribution functions we calculate the correlations\nproduced by a periodically driven scatterer in a system of noninteracting\nelectrons at zero temperature. The multi-particle correlations due to a quantum\nexchange effect are expressed in terms of photon-assisted scattering\namplitudes. The results we obtain are valid for slow but arbitrary in strength\ndriving. We show that even for large amplitude pumps the zero-frequency noise\npower is related to two-particle correlations. In addition to two-particle\ncorrelations a large amplitude pump can generate multi-particle correlations."
    },
    {
        "anchor": "Strongly Correlated Chern Insulators in Magic-Angle Twisted Bilayer\n  Graphene: Interactions among electrons and the topology of their energy bands can\ncreate novel quantum phases of matter. Most topological electronic phases\nappear in systems with weak electron-electron interactions. The instances where\ntopological phases emerge only as a result of strong interactions are rare, and\nmostly limited to those realized in the presence of intense magnetic fields.\nThe discovery of flat electronic bands with topological character in\nmagic-angle twisted bilayer graphene (MATBG) has created a unique opportunity\nto search for new strongly correlated topological phases. Here we introduce a\nnovel local spectroscopic technique using a scanning tunneling microscope (STM)\nto detect a sequence of topological insulators in MATBG with Chern numbers C =\n$\\pm$ 1, $\\pm$ 2, $\\pm$ 3, which form near $\\nu$ = $\\pm$ 3, $\\pm$ 2, $\\pm$ 1\nelectrons per moir\\'e unit cell respectively, and are stabilized by the\napplication of modest magnetic fields. One of the phases detected here (C = +1)\nhas been previously observed when the sublattice symmetry of MATBG was\nintentionally broken by hexagonal boron nitride (hBN) substrates, with\ninteractions playing a secondary role. We demonstrate that strong\nelectron-electron interactions alone can produce not only the previously\nobserved phase, but also new and unexpected Chern insulating phases in MATBG.\nThe full sequence of phases we observed can be understood by postulating that\nstrong correlations favor breaking time-reversal symmetry to form Chern\ninsulators that are stabilized by weak magnetic fields. Our findings illustrate\nthat many-body correlations can create topological phases in moir\\'e systems\nbeyond those anticipated from weakly interacting models.",
        "positive": "Direct spectrum analysis using a threshold detector with application to\n  a superconducting circuit: We introduce a new and quantitative theoretical framework for noise spectral\nanalysis using a threshold detector, which is then applied to a superconducting\ndevice: the Cavity Bifurcation Amplifier (CBA). We show that this new framework\nprovides direct access to the environmental noise spectrum with a sensitivity\napproaching the standard quantum limit of weak continuous measurements. In\naddition, the accessible frequency range of the spectrum is, in principle,\nlimited only by the ring down time of the CBA. This on-chip noise detector is\nnon-dissipative and works with low probing powers, allowing it to be operated\nat low temperatures ($T<15$mK). We exploit this technique for measuring the\nfrequency fluctuations of the CBA and find a low frequency noise with an\namplitude and spectrum compatible with a dielectric origin."
    },
    {
        "anchor": "Optical signatures of charge order in a Mott-Wigner state: The elementary optical excitations in two dimensional semiconductors hosting\nitinerant electrons are attractive and repulsive polarons -- excitons that are\ndynamically screened by electrons. Exciton-polarons have hitherto been studied\nin translationally invariant degenerate Fermi systems. Here, we show that\nelectronic charge order breaks the excitonic translational invariance and leads\nto a direct optical signature in the exciton-polaron spectrum. Specifically, we\ndemonstrate that new optical resonances appear due to spatially modulated\ninteraction between excitons and electrons in an incompressible Mott state. Our\nobservations demonstrate that resonant optical spectroscopy provides an\ninvaluable tool for studying strongly correlated states, such as Wigner\ncrystals and density waves, where exciton-electron interactions are modified by\nthe emergence of new electronic charge or spin order.",
        "positive": "Topological classification under nonmagnetic and magnetic point group\n  symmetry: Application of real-space Atiyah-Hirzebruch spectral sequence to\n  higher-order topology: We classify time-reversal breaking (class A) spinful topological crystalline\ninsulators with crystallographic non-magnetic (32 types) and magnetic (58\ntypes) point groups. The classification includes all possible magnetic\ntopological crystalline insulators protected by point group symmetry. Whereas\nthe classification of topological insulators is known to be given by the\n$K$-theory in the momentum space, computation of the $K$-theory has been a\ndifficult task in the presence of complicated crystallographic symmetry. Here\nwe consider the $K$-homology in the real space for this problem, instead of the\n$K$-theory in the momentum space, both of which give the same topological\nclassification. We apply the Atiyah-Hirzebruch spectral sequence (AHSS) for\ncomputation of the $K$-homology, which is a mathematical tool for generalized\n(co)homology. In the real space picture, the AHSS naturally gives the\nclassification of higher-order topological insulators at the same time. By\nsolving the group extension problem in the AHSS on the basis of physical\narguments, we completely determine possible topological phases including\nhigher-order ones for each point group. Relationships among different\nhigher-order topological phases are argued in terms of the AHSS in the\n$K$-homology. We find that in some nonmagnetic and magnetic point groups, a\nstack of two $\\mathbb{Z}_2$ second-order topological insulators can be smoothly\ndeformed into non-trivial fourth-order topological insulators, which implies\nnon-trivial group extensions in the AHSS."
    },
    {
        "anchor": "Nonlinear localized excitations in a topological ferromagnetic honeycomb\n  lattice: We theoretically investigate nonlinear localized excitations in a Heisenberg\nhoneycomb ferromagnet with a second neighbour Dzialozinskii-Moriya interaction,\nwhich has been proved to possess the topological band structure. Using the\ntime-dependent variational principle, we obtain the equation of motion for the\nsystem in the Glauber coherent-state representation. By means of the\nsemidiscrete multiple-scale method, different types of nonlinear localized\nexcitations are gotten.Our results show that both two-dimensional discrete\nbreathers and bulk gap solitons may occur in the Heisenberg honeycomb\nferromagnet.",
        "positive": "Electronic structure of few-layer black phosphorus from $\u03bc$-ARPES: Black phosphorus (BP) stands out among two-dimensional (2D) semiconductors\nbecause of its high mobility and thickness dependent direct band gap. However,\nthe quasiparticle band structure of ultrathin BP has remained inaccessible to\nexperiment thus far. Here we use a recently developed laser-based micro-focus\nangle resolved photoemission ($\\mu$-ARPES) system to establish the electronic\nstructure of 2-9 layer BP from experiment. Our measurements unveil ladders of\nanisotropic, quantized subbands at energies that deviate from the scaling\nobserved in conventional semiconductor quantum wells. We quantify the\nanisotropy of the effective masses and determine universal tight-binding\nparameters which provide an accurate description of the electronic structure\nfor all thicknesses."
    },
    {
        "anchor": "Laughlin's argument for the quantized thermal Hall effect: We extend Laughlin's magnetic-flux-threading argument to the quantized\nthermal Hall effect. A proper analogue of Laughlin's adiabatic magnetic-flux\nthreading process for the case of the thermal Hall effect is given in terms of\nan external gravitational field. From the perspective of the edge theories of\nquantum Hall systems, the quantized thermal Hall effect is closely tied to the\nbreakdown of large diffeomorphism invariance, that is, a global gravitational\nanomaly. In addition, we also give an argument from the bulk perspective in\nwhich a free energy, decomposed into its Fourier modes, is adiabatically\ntransferred under an adiabatic process involving external gravitational\nperturbations.",
        "positive": "Intercalation of graphene on SiC(0001) via ion-implantation: Electronic devices based on graphene technology are catching on rapidly and\nthe ability to engineer graphene properties at the nanoscale is becoming, more\nthan ever, indispensable. Here, we present a new procedure of graphene\nfunctionalization on SiC(0001) that paves the way towards the fabrication of\ncomplex graphene electronic chips. The procedure resides on the well-known\nion-implantation technique. The efficiency of the working principle is\ndemonstrated by the intercalation of the epitaxial graphene layer on SiC(0001)\nwith Bi atoms, which was not possible following standard procedures. Our\nresults put forward the ion-beam lithography to nanostructure and functionalize\ndesired graphene chips."
    },
    {
        "anchor": "Conduction-radiation coupling between two closely-separated solids: In the theory of radiative heat exchanges between two closely-spaced bodies\nintroduced by Polder and van Hove, no interplay between the heat carriers\ninside the materials and the photons crossing the separation gap is assumed.\nHere we release this constraint by developing a general theory to describe the\nconduction-radiation coupling between two solids of arbitrary size separated by\na subwavelength separation gap. We show that, as a result of the temperature\nprofile induced by the coupling with conduction, the radiative heat flux\nexchanged between two parallel slabs at nanometric distances can be several\norders of magnitude smaller than the one predicted by the conventional theory.\nThese results could have important implications in the fields of nanoscale\nthermal management, near-field solid-state cooling and nanoscale energy\nconversion.",
        "positive": "A novel site-controlled quantum dot system with high uniformity and\n  narrow excitonic emission: We report on the optical properties of a newly developed site-controlled\nInGaAs Dots in GaAs barriers grown in pre-patterned pyramidal recesses by\nmetalorganic vapour phase epitaxy. The inhomogeneous broadening of excitonic\nemission from an ensemble of quantum dots is found to be extremely narrow, with\na standard deviation of 1.19 meV. A dramatic improvement in the spectral purity\nof emission lines from individual dots is also reported (18-30 ueV) when\ncompared to the state-of-the-art for site controlled quantum dots."
    },
    {
        "anchor": "Reflectance of graphene-coated dielectric plates in the framework of\n  Dirac model: Joint action of energy gap and chemical potential: We investigate the reflectance of a dielectric plate coated with a graphene\nsheet which possesses the nonzero energy gap and chemical potential at any\ntemperature. The general formalism for the reflectance using the polarization\ntensor is presented in the framework of Dirac model. It allows calculation of\nthe reflectivity properties for any material plate coated with real graphene\nsheet on the basis offirst principles of quantum electrodynamics. Numerical\ncomputations of the reflectance are performed for the graphene-coated SiO$_2$\nplate at room, liquid-nitrogen, and liquid-helium temperatures. We demonstrate\nthat there is a nontrivial interplay between the chemical potential, energy\ngap, frequency, and temperature in their joint action on the reflectance of a\ngraphene-coated plate. Specifically, it is shown that at the fixed frequency of\nan incident light an increase of the chemical potential and the energy gap\naffect the reflectance in opposite directions by increasing and decreasing it,\nrespectively. According to our results, the reflectance approaches unity at\nsufficiently low frequencies and drops to that of an uncoated plate at high\nfrequencies for any values of the chemical potential and energy gap. The impact\nof temperature on the reflectance is found to be more pronounced for graphene\ncoatings with smaller chemical potentials. The obtained results could be\napplied for optimization of optical detectors and other devices exploiting\ngraphene coatings.",
        "positive": "Quantum optics measurement scheme for quantum geometry and topological\n  invariants: We show how a quantum optical measurement scheme based on heterodyne\ndetection can be used to explore geometrical and topological properties of\ncondensed matter systems. Considering a 2D material placed in a cavity with a\ncoupling to the environment, we compute correlation functions of the photons\nexiting the cavity and relate them to the hybrid light-matter state within the\ncavity. Different polarizations of the intracavity field give access to all\ncomponents of the quantum geometric tensor on contours in the Brillouin zone\ndefined by the transition energy. Combining recent results based on the\nmetric-curvature correspondence with the measured quantum metric allows us to\ncharacterize the topological phase of the material. Moreover, in systems where\n$S_z$ is a good quantum number, the procedure also allows us to extract the\nspin Chern number. As an interesting application, we consider a minimal model\nfor twisted bilayer graphene at the magic angle, and discuss the feasibility of\nextracting the Euler number."
    },
    {
        "anchor": "Non-linear transport without spin-orbit coupling or warping in\n  two-dimensional Dirac semimetals: It has recently been realized that the first-order moment of the Berry\ncurvature, namely the Berry curvature dipole (BCD) can give rise to non-linear\ncurrent in a wide variety of time-reversal invariant and non-centrosymmetric\nmaterials. While the BCD in two-dimensional Dirac systems is known to be finite\nonly in the presence of either substantial spin-orbit coupling where low-energy\nDirac quasiparticles form tilted cones or higher order warping of the Fermi\nsurface, we argue that the low-energy Dirac quasiparticles arising from the\nmerging of a pair of Dirac points without any tilt or warping of the Fermi\nsurface can lead to a non-zero BCD. Remarkably, in such systems, the BCD is\nfound to be independent of Dirac velocity as opposed to the Dirac dispersion\nwith a tilt or warping effects. We further show that the proposed systems can\nnaturally host helicity-dependent photocurrent due to their linear\nmomentum-dependent Berry curvatures. Finally, we discuss an important byproduct\nof this work, i.e., nonlinear anomalous Nernst effect as a second-order thermal\nresponse.",
        "positive": "Confined Electrons in Effective Plane Fractals: As an emerging complex two-dimensional structure, plane fractal has attracted\nmuch attention due to its novel dimension-related physical properties. In this\npaper, we check the feasibility to create an effective Sierpinski carpet (SC),\na plane fractal with Hausdorff dimension intermediate between one and two, by\napplying an external electric field to a square or a honeycomb lattice. The\nelectric field forms a fractal geometry but the atomic structure of the\nunderlying lattice remains the same. By calculating and comparing various\nelectronic properties, we find parts of the electrons can be confined\neffectively in a fractional dimension with a relatively small field, and\nrepresenting properties very close to these in a real fractal. In particular,\ncompared to the square lattice, the external field required to effectively\nconfine the electron is smaller in the hexagonal lattice, suggesting that a\ngraphene-like system will be an ideal platform to construct an effective SC\nexperimentally. Our work paves a new way to build fractals from a top-down\nperspective, and can motivate more studies of fractional dimensions in real\nsystems."
    },
    {
        "anchor": "Orbital-resolved single atom magnetism measured with X-ray absorption\n  spectroscopy: Lanthanide atoms and molecules are promising candidates for atomic data\nstorage and quantum logic due to the long magnetic lifetime of their electron\nquantum states. Accessing these states through electrical transport requires\nthe engineering of their electronic configuration down to the level of\nindividual atomic orbitals. Here, we address the magnetism of surface-supported\nlanthanide atoms, clusters, and films with orbital selectivity using X-ray\nabsorption spectroscopy and magnetic circular dichroism. We exploit the\nselection rules of electric dipole transitions to reveal the occupation and\nmagnetism of the valence electrons of Gd and Ho deposited on MgO/Ag(100).\nComparing our results with multiplet calculations and density functional\ntheory, we identify a charge transfer mechanism that leaves the lanthanide\nspecies in an unconventional singly ionized configuration. Our approach allows\ndetermining the role of valence electrons on the quantum level structure of\nlanthanide-based nanostructures.",
        "positive": "Relaxation, decoherence and steady-state population inversion in qubits\n  doubly dressed by microwave and radiofrequency fields: The coherent dynamics of relaxing spin qubits driven by a classical\nbichromatic field comprising a strong resonant component and a weaker component\nwith a frequency close to the strong-field Rabi frequency is studied. The\ndouble dressing by the bichromatic field modifies dephasing and dissipation\nprocesses. We demonstrate that detuning of the weaker-field frequency from the\nstrong-field Rabi frequency prolongs the decay of Rabi oscillations between\nsome doubly dressed states. The sensitivity of Rabi oscillations to the\nmodified detuning-dependent relaxation is illustrated for nitrogen-vacancy\nqubits in diamond. We discuss a steady-state population inversion of the doubly\ndressed-state levels."
    },
    {
        "anchor": "Generalized constraints on quantum amplification: We derive quantum constraints on the minimal amount of noise added in linear\namplification involving input or output signals whose component operators do\nnot necessarily have c-number commutators, as is the case for fermion currents.\nThis is a generalization of constraints derived for the amplification of\nbosonic fields whose components posses c-number commutators.",
        "positive": "Metal-insulator transition in type II heterostructures based on\n  transition metal dichalcogenides: The problem of screening the Coulomb interaction between charge carriers in\ntype II heterostructures based on transition metal dichalcogenides is\nAnalytically solved. At a sufficiently high density of charge carriers, the\ndensity dependence of the interlayer exciton energy is obtained. The energy of\nthe interlayer exciton tends to zero in the metal--insulator transition point.\nThe presented scheme of calculations makes it possible to find the temperature\ndependence of the density of this transition."
    },
    {
        "anchor": "Exact solutions for a Dirac electron in an exponentially decaying\n  magnetic field: We consider a Dirac electron in the presence of an exponentially decaying\nmagnetic field. We obtain exact energy eigenvalues with a zero-energy state and\nthe corresponding eigenfunctions. We also calculate the probability density and\ncurrent distributions.",
        "positive": "Robust micro-magnet design for fast electrical manipulations of single\n  spins in quantum dots: Tailoring spin coupling to electric fields is central to spintronics and\nspin-based quantum information processing. We present an optimal micromagnet\ndesign that produces appropriate stray magnetic fields to mediate fast\nelectrical spin manipulations in nanodevices. We quantify the practical\nrequirements for spatial field inhomogeneity and tolerance for misalignment\nwith spins, and propose a design scheme to improve the spin-rotation frequency\n(to exceed 50MHz in GaAs nanostructures). We then validate our design by\nexperiments in separate devices. Our results will open a route to rapidly\ncontrol solid-state electron spins with limited lifetimes and to study coherent\nspin dynamics in solids."
    },
    {
        "anchor": "Multi-dimensional microwave sensing using graphene waveguides: This paper presents an electrolytically gated broadband microwave sensor\nwhere atomically-thin graphene layers are integrated into coplanar waveguides\nand coupled with microfluidic channels. The interaction between a solution\nunder test and the graphene surface causes material and concentration-specific\nmodifications of graphene's DC and AC conductivity. Moreover, wave propagation\nin the waveguide is modified by the dielectric properties of materials in its\nclose proximity via the fringe field, resulting in a combined sensing mechanism\nleading to an enhanced S-parameter response compared to metallic microwave\nsensors. The possibility of further controlling the graphene conductivity via\nan electrolytic gate enables a new, multi-dimensional approach merging chemical\nfield-effect sensing and microwave measurement methods. By controlling and\nsynchronizing frequency sweeps, electrochemical gating and liquid flow in the\nmicrofluidic channel, we generate multidimensional datasets that enable a\nthorough investigation of the solution under study. As proof of concept, we\nfunctionalize the graphene surface in order to identify specific\nsingle-stranded DNA sequences dispersed in phosphate buffered saline solution.\nWe achieve a limit of detection of ~1 attomole per litre for a perfect match\nDNA strand and a sensitivity of ~3 dB/decade for sub-pM concentrations. These\nresults show that our devices represent a new and accurate metrological tool\nfor chemical and biological sensing.",
        "positive": "Wide ferromagnetic domain walls can host both adiabatic reflectionless\n  spin transport and finite nonadiabatic spin torque: A time-dependent quantum\n  transport picture: The key concept in spintronics of current-driven noncollinear magnetic\ntextures, such as magnetic domain walls (DWs), is adiabaticity, i.e., how\nclosely electronic spins track classical localized magnetic moments (LMMs) of\nthe texture. When mistracking occurs nonadiabatic effects arise, the salient of\nwhich is nonadiabatic spin transfer torque (STT) where spin angular momentum is\nexchanged between electrons and LMMs to cause their dynamics and enable DW\nmotion without any current threshold. The microscopic mechanisms behind\nnonadiabatic STT have been debated theoretically for nearly two decades, but\nwith unanimous conclusion that they should be significant only in narrow DWs.\nHowever, this contradicts sharply experiments [O. Boulle {\\em et al.}, Phys.\nRev. Lett. {\\bf 101}, 216601 (2008); C. Burrowes {\\em et al.}, Nat. Phys. {\\bf\n6}, 17 (2010)] observing nonadiabatic STT in DWs much wider than putatively\nrelevant $\\sim 1$ nm scale, as well as largely insensitive to further\nincreasing the DW width $w$. Here we employ time-dependent quantum transport\nfor electrons to obtain both nonadiabatic and adiabatic STT from the exact\nnonequilibrium density matrix and its lowest order as adiabatic density matrix\ndefined by assuming that LMMs are infinitely slow. This allows us to\ndemonstrate that our microscopically, and without any simplifications of prior\nderivations like effectively static DW, extracted nonadiabatic STT: (i) does\nnot decay, but instead saturates at a finite value, with increasing $w$ of a\nmoving DW ensuring entry into the adiabatic limit, which we characterize by\nshowing that electronic spins do not reflect from the static DW in this limit;\nand (ii) it has both out-of-DW-plane, as is the case of phenomenological\nexpression widely used in the LLG equation, and in-plane components, where the\nformer remains finite with increasing $w$."
    },
    {
        "anchor": "Ultrafast evanescent heat transfer across solid interfaces via\n  hyperbolic phonon polaritons in hexagonal boron nitride: The efficiency of phonon-mediated heat transport is limited by the intrinsic\natomistic properties of materials, seemingly providing an upper limit to heat\ntransfer in materials and across their interfaces. The typical speeds of\nconductive transport, which are inherently limited by the chemical bonds and\natomic masses, dictate how quickly heat will move in solids. Given that\nphonon-polaritons, or coupled phonon-photon modes, can propagate at speeds\napproaching 1 percent of the speed of light - orders of magnitude faster than\ntransport within a pure diffusive phonon conductor - we demonstrate that\nvolume-confined, hyperbolic phonon-polariton(HPhP) modes supported by many\nbiaxial polar crystals can couple energy across solid-solid interfaces at an\norder of magnitude higher rates than phonon-phonon conduction alone. Using\npump-probe thermoreflectance with a mid-infrared, tunable, probe pulse with\nsub-picosecond resolution, we demonstrate remote and spectrally selective\nexcitation of the HPhP modes in hexagonal boron nitride in response to\nradiative heating from a thermally emitting gold source. Our work demonstrates\na new avenue for interfacial heat transfer based on broadband radiative\ncoupling from a hot spot in a gold film to hBN HPhPs, independent of the broad\nspectral mismatch between the pump(visible) and probe(mid-IR) pulses employed.\nThis methodology can be used to bypass the intrinsically limiting phonon-phonon\nconductive pathway, thus providing an alternative means of heat transfer across\ninterfaces. Further, our time-resolved measurements of the temperature changes\nof the HPhP modes in hBN show that through polaritonic coupling, a material can\ntransfer heat across and away from an interface at rates orders of magnitude\nfaster than diffusive phonon speeds intrinsic to the material, thus\ndemonstrating a pronounced thermal transport enhancement in hBN via\nphonon-polariton coupling.",
        "positive": "The relaxation time of a chiral quantum R-L circuit: We report on the GHz complex admittance of a chiral one dimensional ballistic\nconductor formed by edge states in the quantum Hall regime. The circuit\nconsists of a wide Hall bar (the inductor L) in series with a tunable resistor\n(R) formed by a quantum point contact. Electron interactions between edges are\nscreened by a pair of side gates. Conductance steps are observed on both real\nand imaginary parts of the admittance. Remarkably, the phase of the admittance\nis transmission-independent. This shows that the relaxation time of a chiral\nR-L circuit is resistance independent. A current and charge conserving\nscattering theory is presented that accounts for this observation with a\nrelaxation time given by the electronic transit time in the c cuit."
    },
    {
        "anchor": "Detection of incoherent broadband terahertz light using antenna-coupled\n  high-electron-mobility field-effect transistors: The sensitivity of direct terahertz detectors based on self-mixing of\nterahertz electromagnetic wave in field-effect transistors is being improved\nwith noise-equivalent power close to that of Schottky-barrier-diode detectors.\nHere we report such detectors based on AlGaN/GaN two-dimensional electron gas\nat 77~K are able to sense broadband and incoherent terahertz radiation. The\nmeasured photocurrent as a function of the gate voltage agrees well with the\nself-mixing model and the spectral response is mainly determined by the\nantenna. A Fourier-transform spectrometer equipped with detectors designed for\n340, 650 and 900~GHz bands allows for terahertz spectroscopy in a frequency\nrange from 0.1 to 2.0~THz. The 900~GHz detector at 77~K offers an optical\nsensitivity about $1~\\mathrm{pW/\\sqrt{Hz}}$ being comparable to a commercial\nsilicon bolometer at 4.2~K. By further improving the sensitivity,\nroom-temperature detectors would find applications in active/passive terahertz\nimaging and terahertz spectroscopy.",
        "positive": "Current vortices in aromatic carbon molecules: The local current flow through three small aromatic carbon molecules, namely\nbenzene, naphthalene and anthracene, is studied. Applying density functional\ntheory and the non-equilibrium Green's function method for transport, we\ndemonstrate that pronounced current vortices exist at certain electron energies\nfor these molecules. The intensity of these circular currents, which appear not\nonly at the anti-resonances of the transmission but also in vicinity of its\nmaxima, can exceed the total current flowing through the molecular junction and\ngenerate considerable magnetic fields. The $\\pi$ electron system of the\nmolecular junctions is emulated experimentally by a network of macroscopic\nmicrowave resonators. The local current flows in these experiments confirm the\nexistence of current vortices as a robust property of ring structures. The\ncircular currents can be understood in terms of a simple nearest-neighbor\ntight-binding H\\\"uckel model. Current vortices are caused by the interplay of\nthe complex eigenstates of the open system which have energies close-by the\nconsidered electron energy. Degeneracies, as observed in benzene and\nanthracene, can thus generate strong circular currents, but also non-degenerate\nsystems like naphthalene exhibit current vortices. Small imperfections and\nperturbations can couple otherwise uncoupled states and induce circular\ncurrents."
    },
    {
        "anchor": "Enhancement of Resonant Energy Transfer Due to Evanescent-wave from the\n  Metal: The high density of evanescent modes in the vicinity of a metal leads to\nenhancement of the near-field F\\\"{o}rster resonant energy transfer (FRET) rate.\nWe present a classical approach to calculate the FRET rate based on the dyadic\nGreen's function of an arbitrary dielectric environment, and consider non-local\nlimit of material permittivity in case of metallic halfspace and thin film. In\na dimer system, we find that the FRET rate is enhanced due to shared evanescent\nphoton modes bridging a donor and an acceptor. Furthermore, a general\nexpression for the FRET rate for multimer systems is derived. The presence of a\ndielectric environment and the path interference effect enhance the transfer\nrate, depending on the combination of distance and geometry.",
        "positive": "Few-body systems in condensed matter physics: This review focuses on the studies and computations of few-body systems of\nelectrons and holes in condensed matter physics. We analyze and illustrate the\napplication of a variety of methods for description of two- three- and\nfour-body excitonic complexes such as an exciton, trion and biexciton in\nthree-, two- and one-dimensional configuration spaces in various types of\nmaterials. We discuss and analyze the contributions made over the years to\nunderstanding how the reduction of dimensionality affects the binding energy of\nexcitons, trions and biexcitons in bulk and low dimensional semiconductors and\naddress the challenges that still remain."
    },
    {
        "anchor": "Visualizing Electrical Breakdown and ON/OFF States in Electrically\n  Switchable Suspended Graphene Break Junctions: Narrow gaps are formed in suspended single to few layer graphene devices\nusing a pulsed electrical breakdown technique. The conductance of the resulting\ndevices can be programmed by the application of voltage pulses, with a voltage\nof 2.5V~4.5V corresponding to an ON pulse and voltages ~8V corresponding to OFF\npulses. Electron microscope imaging of the devices shows that the graphene\nsheets typically remain suspended and that the device conductance tends to zero\nwhen the observed gap is large. The switching rate is strongly temperature\ndependent, which rules out a purely electromechanical switching mechanism. This\nobserved switching in suspended graphene devices strongly suggests a switching\nmechanism via atomic movement and/or chemical rearrangement, and underscores\nthe potential of all-carbon devices for integration with graphene electronics.",
        "positive": "Non-Hermitian topology in monitored quantum circuits: We demonstrate that genuinely non-Hermitian topological phases and\ncorresponding topological phase transitions can be naturally realized in\nmonitored quantum circuits, exemplified by the paradigmatic non-Hermitian\nSu-Schrieffer-Heeger model. We emulate this model by a 1D chain of spinless\nelectrons evolving under unitary dynamics and subject to periodic measurements\nthat are stochastically invoked. The non-Hermitian topology is visible in\ntopological invariants adapted to the context of monitored circuits. For\ninstance, the topological phase diagram of the monitored realization of the\nnon-Hermitian Su-Schrieffer-Heeger model is obtained from the biorthogonal\npolarization computed from an effective Hamiltonian of the monitored system.\nImportantly, our monitored circuit realization allows direct access to steady\nstate biorthogonal expectation values of generic observables, and hence, to\nmeasure physical properties of a genuine non-Hermitian model. We expect our\nresults to be applicable more generally to a wide range of models that host\nnon-Hermitian topological phases."
    },
    {
        "anchor": "Bloch Oscillations of an Exciton-polariton Bose-Einstein Condensate: We study theoretically Bloch oscillations of half-matter, half-light\nquasi-particles: exciton-polaritons. We propose an original structure for the\nobservation of this phenomenon despite the constraints imposed by the\nrelatively short lifetime of the particles and the limitations on the\nengineered periodic potential. First, we focus on the linear regime in a\nperfect lattice where regular oscillations are obtained. Second, we take into\naccount a realistic structural disorder known to localize non-interacting\nparticles, which is quite dramatic for propagation-related phenomena. In the\nnon-linear condensed regime the renormalization of the energy provided by\ninteractions between particles allows us to screen efficiently the disorder and\nto recover oscillations. This effect is useful only in a precise range of\nparameters outside of which the system becomes dynamically unstable. For a\nlarge chemical potential of the order of the potential's amplitude, a strong\nLandau-Zener tunneling tends to completely delocalize particles.",
        "positive": "Topological spin textures in electronic non-Hermitian systems: Non-Hermitian systems have been discussed mostly in the context of open\nsystems and nonequilibrium. Recent experimental progress is much from optical,\ncold-atomic, and classical platforms due to the vast tunability and clear\nidentification of observables. However, their counterpart in solid-state\nelectronic systems in equilibrium remains unmasked although highly desired,\nwhere a variety of materials are available, calculations are solidly founded,\nand accurate spectroscopic techniques can be applied. We demonstrate that, in\nthe surface state of a topological insulator with spin-dependent relaxation due\nto magnetic impurities, highly nontrivial topological soliton spin textures\nappear in momentum space. Such spin-channel phenomena are delicately related to\nthe type of non-Hermiticity and correctly reveal the most robust non-Hermitian\nfeatures detectable spectroscopically. Moreover, the distinct topological\nsoliton objects can be deformed to each other, mediated by topological\ntransitions driven by tuning across a critical direction of doped magnetism.\nThese results not only open a solid-state avenue to exotic spin patterns via\nspin- and angle-resolved photoemission spectroscopy, but also inspire\nnon-Hermitian dissipation engineering of spins in solids."
    },
    {
        "anchor": "Comparative study of the binding energy in a thin and ultra-thin\n  organic-inorganic perovskite within dielectric mismatches effects: The multi-quantum well (MQW) organic-inorganic perovskite offer an approach\nof tuning the exciton binding energy based on the well-barrier dielectric\nmismatch effect, which called the image charge effect. The exfoliation from MQW\norganic-inorganic perovskite forms a twodimensional (2D) nano-sheet. As with\nother 2D materials, like graphene or transition metal dichalcogenides (TMDs),\nthe ultra-thin perovskites layers are highly sensitive to the dielectric\nenvironment. We investigate the ultrathin crystalline 2D van-der-Waals (vdW)\nlayers of organic-inorganic perovskite crystals close to a surface of the\nsubstrate. We show that binding exciton energy is strongly influenced by the\nsurrounding dielectric environment. We find that the Keldysh model somehow\nestimates the strong dependence of the exciton binding energies on\nenvironmental screening. We compare our binding energies results with\nexperimental results in the (C6H13NH3)2PbI4 perovskite, and we estimate the\nbinding energy values of (C4H9NH3)2PbBr4.",
        "positive": "A reduced model for precessional switching of thin-film nanomagnets\n  under the influence of spin-torque: We study the magnetization dynamics of thin-film magnetic elements with\nin-plane magnetization subject to a spin-current flowing perpendicular to the\nfilm plane. We derive a reduced partial differential equation for the in-plane\nmagnetization angle in a weakly damped regime. We then apply this model to\nstudy the experimentally relevant problem of switching of an elliptical element\nwhen the spin-polarization has a component perpendicular to the film plane,\nrestricting the reduced model to a macrospin approximation. The macrospin\nordinary differential equation is treated analytically as a weakly damped\nHamiltonian system, and an orbit-averaging method is used to understand\ntransitions in solution behaviors in terms of a discrete dynamical system. The\npredictions of our reduced model are compared to those of the full\nLandau--Lifshitz--Gilbert--Slonczewski equation for a macrospin."
    },
    {
        "anchor": "Electron-beam propagation in a two-dimensional electron gas: A quantum mechanical model based on a Green's function approach has been used\nto calculate the transmission probability of electrons traversing a\ntwo-dimensional electron gas injected and detected via mode-selective quantum\npoint contacts. Two-dimensional scattering potentials, back-scattering, and\ntemperature effects were included in order to compare the calculated results\nwith experimentally observed interference patterns. The results yield detailed\ninformation about the distribution, size, and the energetic height of the\nscattering potentials.",
        "positive": "Theory of Orbital Pumping: We develop a theory of orbital pumping, which corresponds to the emission of\norbital currents from orbital dynamics. This phenomenon exhibits two distinct\ncharacteristics compared to spin pumping. Firstly, while spin pumping generates\nsolely spin (angular momentum) currents, orbital pumping yields both orbital\nangular momentum currents and orbital angular position currents. Secondly,\nlattice vibrations induce orbital dynamics and associated orbital pumping as\nthe orbital angular position is directly coupled to the lattice. These pumped\norbital currents can be detected as transverse electric voltages via the\ninverse orbital(-torsion) Hall effect, stemming from orbital textures. Our work\nproposes a new avenue for generating orbital currents and provides a broader\nunderstanding of angular momentum dynamics encompassing spin, orbital, and\nphonon."
    },
    {
        "anchor": "Fractional spin and Josephson effect in time-reversal-invariant\n  topological superconductors: Time reversal invariant topological superconducting (TRITOPS) wires are known\nto host a fractional spin hbar/4 at their ends. We investigate how this\nfractional spin affects the Josephson current in a TRITOPS-quantum dot-TRITOPS\nJosephson junction, describing the wire in a model which can be tuned between a\ntopological and a nontopological phase. We compute the equilibrium Josephson\ncurrent of the full model by continuous-time Monte Carlo simulations and\ninterpret the results within an effective low-energy theory. We show that in\nthe topological phase, the 0-to-pi transition is quenched via formation of a\nspin singlet from the quantum dot spin and the fractional spins associated with\nthe two adjacent topological superconductors.",
        "positive": "Enhancement of mechanical Q-factors by optical trapping: The quality factor of a mechanical resonator is an important figure of merit\nfor various sensing applications and for observing quantum behavior. Here, we\ndemonstrate a technique to push the quality factor of a micro-mechanical\nresonator beyond conventional material and fabrication limits by using an\noptical field to stiffen or \"trap\" a particular motional mode. Optical forces\nincrease the oscillation frequency by storing most of the mechanical energy in\na lossless optical potential, thereby strongly diluting the effect of material\ndissipation. By using a 130 nm thick SiO$_2$ disk as a suspended pendulum, we\nachieve an increase in the pendulum center-of-mass frequency from 6.2 kHz to\n145 kHz. The corresponding quality factor increases 50-fold from its intrinsic\nvalue to a final value of $Q=5.8(1.1)\\times 10^5$, representing more than an\norder of magnitude improvement over the conventional limits of SiO$_2$ for this\ngeometry. Our technique may enable new opportunities for mechanical sensing and\nfacilitate observations of quantum behavior in this class of mechanical\nsystems."
    },
    {
        "anchor": "Unsupervised learning of topological phase diagram using topological\n  data analysis: Topology and machine learning are two actively researched topics not only in\ncondensed matter physics, but also in data science. Here, we propose the use of\ntopological data analysis in unsupervised learning of the topological phase\ndiagrams. This is possible because the quantum distance can capture the shape\nof the space formed by the Bloch wavefunctions as we sweep over the Brillouin\nzone. Therefore, if we minimize the volume of the space formed by the\nwavefunction through a continuous deformation, the wavefunctions will end up\nforming distinct spaces which depend on the topology of the wavefunctions.\nCombining this observation with the topological data analysis, which provides\ntools such as the persistence diagram to capture the topology of the space\nformed by the wavefunctions, we can cluster together Hamiltonians that give\nrise to similar persistence diagrams after the deformation. By examining these\nclusters as well as representative persistence diagrams in the clusters, we can\ndraw the phase diagram as well as distinguish between topologically trivial and\nnontrivial phases. Our proposal to minimize the volume can be interpreted as\nfinding geodesics in 1D Brillouin zone, and minimal surfaces in 2D and\nhigher-dimensional Brillouin zones. Using this interpretation, we can guarantee\nthe convergence of the minimization under certain conditions, which is an\noutstanding feature of our algorithm. We demonstrate the working principles of\nour machine learning algorithm using various models.",
        "positive": "Modeling Single Molecule Junction Mechanics as a Probe of Interface\n  Bonding: Using the atomic force microscope based break junction approach, applicable\nto metal point contacts and single molecule junctions, measurements can be\nrepeated thousands of times resulting in rich data sets characterizing the\nproperties of an ensemble of nanoscale junction structures. This paper focuses\non the relationship between the measured force extension characteristics\nincluding bond rupture and the properties of the interface bonds in the\njunction. A set of exemplary model junction structures have been analyzed using\ndensity functional theory based calculations to simulate the adiabatic\npotential surface that governs the junction elongation. The junction structures\ninclude representative molecules that bond to the electrodes through amine,\nmethylsulfide and pyridine links. The force extension characteristics are shown\nto be most effectively analyzed in a scaled form with maximum sustainable force\nand the distance between the force zero and force maximum as scale factors.\nWidely used, two parameter models for chemical bond potential energy versus\nbond length are found to be nearly identical in scaled form. Furthermore, they\nfit well to the present calculations of N-Au and S-Au donor-acceptor bonds,\nprovided no other degrees of freedom are allowed to relax. Examination of the\nreduced problem of a single interface, but including relaxation of atoms\nproximal to the interface bond, shows that a single-bond potential form\nrenormalized by an effective harmonic potential in series fits well to the\ncalculated results. This allows relatively accurate extraction of the interface\nbond energy. Analysis of full junction models show cooperative effects that go\nbeyond the series inclusion of the second bond in the junction, the spectator\nbond that does not rupture."
    },
    {
        "anchor": "Ultrafast optical control of entanglement between two quantum dot spins: The interaction between two quantum bits enables entanglement, the\ntwo-particle correlations that are at the heart of quantum information science.\nIn semiconductor quantum dots much work has focused on demonstrating single\nspin qubit control using optical techniques. However, optical control of\nentanglement of two spin qubits remains a major challenge for scaling from a\nsingle qubit to a full-fledged quantum information platform. Here, we combine\nadvances in vertically-stacked quantum dots with ultrafast laser techniques to\nachieve optical control of the entangled state of two electron spins. Each\nelectron is in a separate InAs quantum dot, and the spins interact through\ntunneling, where the tunneling rate determines how rapidly entangling\noperations can be performed. The two-qubit gate speeds achieved here are over\nan order of magnitude faster than in other systems. These results demonstrate\nthe viability and advantages of optically controlled quantum dot spins for\nmulti-qubit systems.",
        "positive": "Thermal Conductivity of Suspended Graphene with Defects: We investigate the thermal conductivity of suspended graphene as a function\nof the density of defects, ND, introduced in a controllable way. Graphene\nlayers are synthesized using chemical vapor deposition, transferred onto a\ntransmission electron microscopy grid, and suspended over ~7.5-micrometer size\nsquare holes. Defects are induced by irradiation of graphene with the\nlow-energy electron beam (20 keV) and quantified by the Raman D-to-G peak\nintensity ratio. As the defect density changes from 2.0x10^10 cm-2 to 1.8x10^11\ncm-2 the thermal conductivity decreases from ~(1.8+/-0.2)x10^3 W/mK to\n~(4.0+/-0.2)x10^2 W/mK near room temperature. At higher defect densities, the\nthermal conductivity reveals an intriguing saturation behavior at a relatively\nhigh value of ~400 W/mK. The thermal conductivity dependence on defect density\nis analyzed using the Boltzmann transport equation and molecular dynamics\nsimulations. The results are important for understanding phonon - point defect\nscattering in two-dimensional systems and for practical applications of\ngraphene in thermal management."
    },
    {
        "anchor": "Interlayer Exciton-Phonon Bound State in Bi2Se3/monolayer WS2 van der\n  Waals Heterostructures: The ability to assemble layers of two-dimensional (2D) materials to form\npermutations of van der Waals heterostructures provides significant\nopportunities in materials design and synthesis. Interlayer interactions\nprovide a path to new properties and functionality, and understanding such\ninteractions is essential to that end. Here we report formation of interlayer\nexciton-phonon bound states in Bi2Se3/WS2 heterostructures, where the Bi2Se3\nA1(3) surface phonon, a mode particularly susceptible to electron-phonon\ncoupling, is imprinted onto the excitonic emission of the WS2. The\nexciton-phonon bound state (or exciton-phonon quasiparticle) presents itself as\nevenly separated peaks superposed on the WS2 excitonic photoluminescence\nspectrum, whose periodic spacing corresponds to the A1(3) surface phonon\nenergy. Low-temperature polarized Raman spectroscopy of Bi2Se3 reveals intense\nsurface phonons and local symmetry breaking that allows the A1(3) surface\nphonon to manifest in otherwise forbidden scattering geometries. Our work\nadvances knowledge of the complex interlayer van der Waals interactions, and\nfacilitates technologies that combine the distinctive transport and optical\nproperties from separate materials into one device for possible spintronics,\nvalleytronics, and quantum computing applications.",
        "positive": "Maximizing Specific Loss Power for Magnetic Hyperthermia by Hard-Soft\n  Mixed Ferrites: We report maximized specific loss power and intrinsic loss power approaching\ntheoretical limits for AC magnetic field heating of nanoparticles. This is\nachieved by engineering the effective magnetic anisotropy barrier of\nnanoparticles via alloying of hard and soft ferrites. 22 nm\nCo0.03Mn0.28Fe2.7O4/SiO2 NPs reached a specific loss power value of 3417\nW/gmetal at a field of 33 kA/m and 380 kHz. Biocompatible Zn0.3Fe2.7O4/SiO2\nnanoparticles achieved specific loss power of 500 W/gmetal and intrinsic loss\npower of 26.8 nHm2/kg at field parameters of 7 kA/m and 380 kHz, below the\nclinical safety limit. Magnetic bone cement achieved heating adequate for bone\ntumor hyperthermia, incorporating ultralow dosage of just 1 wt% of\nnanoparticles. In cellular hyperthermia experiments, these nanoparticles\ndemonstrated high cell death rate at low field parameters. Zn0.3Fe2.7O4/SiO2\nnanoparticles show cell viabilities above 97% at concentrations up to 0.5 mg/ml\nwithin 48 hrs, suggesting toxicity lower than that of magnetite."
    },
    {
        "anchor": "Binding Energy and Lifetime of Excitons in Metallic Nanotubes: The difficulty of describing excitons in semiconducting SWNTs analytically\nlies with the fact that excitons can neither be considered strictly 1D nor 2D\nobjects. However, the situation changes in the case of metallic nanotubes\nwhere, by virtue of screening from gapless metallic subbands, the radius of the\nexciton becomes much larger than the radius of the nanotube $R_\\text{ex}\\gg R$.\nTaking advantage of this, we develop the theory of excitons in metallic\nnanotubes, determining that their binding energy is about $0.08v/R$, in\nagreement with the existing experimental data. Additionally, because of the\npresence of the gapless subbands, there are processes where bound excitons are\nscattered into unbound electron-hole pairs belonging to the gapless subbands.\nSuch processes lead to a finite exciton lifetime and the broadening of its\nspectral function. We calculate the corresponding decay rate of the excitons.",
        "positive": "Electronic transport through a local state linearly coupled to phonon\n  modes: A resolvent formalism is applied to the problem of inelastic scattering of an\nelectron linearly coupled to a set of phonon modes. It is shown how the many\nphonon mode coupling and excitation can be reduced to a single phonon mode\ndescription, consistent with other approaches to the phenomenon of inelastic\ntunneling in heterostructures. A unifying connection is made with the phenomena\nof resonant electron scattering through molecules in the gas phase and of\ntunneling of electrons through adsorbates in scanning tunneling microscopy."
    },
    {
        "anchor": "Euler equation of the optimal trajectory for the fastest magnetization\n  reversal of nano-magnetic structures: Based on the modified Landau-Lifshitz-Gilbert equation for an arbitrary\nStoner particle under an external magnetic field and a spin-polarized electric\ncurrent, differential equations for the optimal reversal trajectory, along\nwhich the magnetization reversal is the fastest one among all possible reversal\nroutes, are obtained. We show that this is a Euler-Lagrange problem with\nconstrains. The Euler equation of the optimal trajectory is useful in designing\na magnetic field pulse and/or a polarized electric current pulse in\nmagnetization reversal for two reasons. 1) It is straightforward to obtain the\nsolution of the Euler equation, at least numerically, for a given magnetic\nnano-structure characterized by its magnetic anisotropy energy. 2) After\nobtaining the optimal reversal trajectory for a given magnetic nano-structure,\nfinding a proper field/current pulse is an algebraic problem instead of the\noriginal nonlinear differential equation.",
        "positive": "Effect of the disorder in graphene grain boundaries: A wave packet\n  dynamics study: Chemical vapor deposition (CVD) on Cu foil is one of the most promising\nmethods to produce graphene samples despite of introducing numerous grain\nboundaries into the perfect graphene lattice. A rich variety of GB structures\ncan be realized experimentally by controlling the parameters in the CVD method.\nGrain boundaries contain non-hexagonal carbon rings (4,5,7,8 membered rings)\nand vacancies in various ratios and arrangements. Using wave packet dynamic\n(WPD) simulations and tight-binding electronic structure calculations, we have\nstudied the effect of the structure of GBs on the transport properties. Three\nmodel GBs with increasing disorder were created in the computer: a periodic 5-7\nGB, a \"serpentine\" GB, and a disordered GB containing 4,8 membered rings and\nvacancies. It was found that for small energies (E=EF+-1eV) the transmission\ndecreases with increasing disorder. Four membered rings and vacancies are\nidentified as the principal scattering centres. Revealing the connection\nbetween the properties of GBs and the CVD growth method may open new\nopportunities in the graphene based nanoelectronics."
    },
    {
        "anchor": "Direct surface cyclotron resonance terahertz emission from a quantum\n  cascade structure: A strong magnetic field applied along the growth direction of a semiconductor\nquantum well gives rise to a spectrum of discrete energy states, the Landau\nlevels. By combining quantum engineering of a quantum cascade structure with a\nstatic magnetic field, we can selectively inject electrons into the excited\nLandau level of a quantum well and realize a tunable surface emitting device\nbased on cyclotron emission. By applying the appropriate magnetic field between\n0 and 12 T, we demonstrate emission from a single device over a wide range of\nfrequencies (1-2 THz and 3-5 THz).",
        "positive": "The Quantum Hall Transition in Real Space: From Localized to Extended\n  States: Using scanning tunneling spectroscopy in ultra-high vacuum at low temperature\n(T = 0.3 K) and high magnetic fields (B < 12 T), we directly probe electronic\nwave functions across an integer quantum Hall transition. In accordance with\ntheoretical predictions, we observe the evolution from localized drift states\nin the insulating phases to branched extended drift states at the quantum\ncritical point. The observed microscopic behavior close to the extended state\nindicates points of localized quantum tunneling, which are considered to be\ndecisive for a quantitative description of the transition."
    },
    {
        "anchor": "Strain-induced programmable half-metal and spin-gapless semiconductor in\n  an edge-doped boron nitride nanoribbon: The search for half-metals and spin-gapless semiconductors has attracted\nextensive attention in material design for spintronics. Existing progress in\nsuch a search often requires peculiar atomistic lattice configuration and also\nlacks active control of the resulting electronic properties. Here we reveal\nthat a boron-nitride nanoribbon with a carbon-doped edge can be made a\nhalf-metal or a spin-gapless semiconductor in a programmable fashion. The\nmechanical strain serves as the on/off switches for functions of half-metal and\nspin-gapless semiconductor to occur. Our findings shed light on how the edge\ndoping combined with strain engineering can affect electronic properties of\ntwo-dimensional materials",
        "positive": "Theory and simulation of quantum photovoltaic devices based on the\n  non-equilibrium Green's function formalism: This article reviews the application of the non-equilibrium Green's function\nformalism to the simulation of novel photovoltaic devices utilizing quantum\nconfinement effects in low dimensional absorber structures. It covers\nwell-known aspects of the fundamental NEGF theory for a system of interacting\nelectrons, photons and phonons with relevance for the simulation of\noptoelectronic devices and introduces at the same time new approaches to the\ntheoretical description of the elementary processes of photovoltaic device\noperation, such as photogeneration via coherent excitonic absorption,\nphonon-mediated indirect optical transitions or non-radiative recombination via\ndefect states. While the description of the theoretical framework is kept as\ngeneral as possible, two specific prototypical quantum photovoltaic devices, a\nsingle quantum well photodiode and a silicon-oxide based superlattice absorber,\nare used to illustrated the kind of unique insight that numerical simulations\nbased on the theory are able to provide."
    },
    {
        "anchor": "Modal decomposition of a propagating matter wave via electron\n  ptychography: We employ ptychography, a phase-retrieval imaging technique, to show\nexperimentally for the first time that a partially coherent high-energy matter\n(electron) wave emanating from an extended source can be decomposed into a set\nof mutually independent modes of minimal rank. Partial coherence significantly\ndetermines the optical transfer properties of an electron microscope and so\nthere has been much work on this subject. However, previous studies have\nemployed forms of interferometry to determine spatial coherence between\ndiscrete points in the wavefield. Here we use the density matrix to derive a\nformal quantum mechanical description of electron ptychography and use it to\nmeasure a full description of the spatial coherence of a propagating matter\nwavefield, at least to the within the fundamental uncertainties of the\nmeasurements we can obtain.",
        "positive": "Relaxation and coherent oscillations in the spin dynamics of II-VI\n  diluted magnetic quantum wells: We study theoretically the ultrafast spin dynamics of II-VI diluted magnetic\nquantum wells in the presence of spin-orbit interaction. We extend a recent\nstudy where it was shown that the spin-orbit interaction and the exchange sd\ncoupling in bulk and quantum wells can compete resulting in qualitatively new\ndynamics when they act simultaneously. We concentrate on\nHg$_{1-x-y}$Mn$_x$Cd$_y$Te quantum wells, which have a highly tunable Rashba\nspin-orbit coupling. Our calculations use a recently developed formalism which\nincorporates electronic correlations originating from the exchange\n$sd$-coupling. We find that the dependence of electronic spin oscillations on\nthe excess energy changes qualitatively depending on whether or not the\nspin-orbit interaction dominates or is of comparable strength with the sd\ninteraction."
    },
    {
        "anchor": "Nanopore creation in graphene at the nanoscale for water desalination: Creating nanopores in graphene is a powerful tool for engineering its\nproperties. Nanopores in graphene tune their electrical, optical, magnetic, and\nmechanical properties. However, controlling nanopores formation at the\nnanoscale level remains a significant challenge. We report an easy method to\ncontrol nanopore sizes using argon-plasma magnetron sputtering. By calculating\nand measuring Raman spectra, we show that the nano-pores in graphene are\ncontrollable and size-tunable. Furthermore, we report that the graphene Raman\nmode around 1450 cm-1, which was attributed to the substrate effect, is due to\nnanopores.\n  We also propose here a novel graphene device-based water filtration. Our\nproposed concept of two graphene electrodes with nanopores on the substrate\n(SiC and SiO2) makes it possible to have the highest permeability value,\nkeeping almost 100 % salt rejection and improving its mechanical properties.\nThese reported results are essential for developing water desalination\nmembranes based on graphene devices.",
        "positive": "Non-quantized Dirac monopoles and strings in the Berry phase of\n  anisotropic spin systems: The Berry phase of an anisotropic spin system that is adiabatically rotated\nalong a closed circuit C is investigated. It is shown that the Berry phase\nconsists of two contributions: (i) a geometric contribution which can be\ninterpreted as the flux through C of a non-quantized Dirac monopole, and (ii) a\ntopological contribution which can be interpreted as the flux through C of a\nDirac string carrying a non-quantized flux, i.e., a spin analogue of the\nAharonov-Bohm effect. Various experimental consequences of this novel effect\nare discussed."
    },
    {
        "anchor": "Stability of skyrmion lattices and symmetries of quasi-two-dimensional\n  chiral magnets: Recently, there has been substantial interest in realizations of skyrmions,\nin particular in 2D systems due to increased stability resulting from reduced\ndimensionality. A stable skyrmion, representing the smallest realizable\nmagnetic texture, could be an ideal element for ultra-dense magnetic memories.\nHere, we use the most general form of the 2D free energy with\nDzyaloshinskii-Moriya interactions constructed from general symmetry\nconsiderations reflecting the underlying system. We predict that skyrmion phase\nis robust and it is present even when the system lacks the in-plane rotational\nsymmetry. In fact, the lowered symmetry leads to increased stability of\nvortex-antivortex lattices with four-fold symmetry and in-plane spirals, in\nsome instances even in the absence of an external magnetic field. Our results\nrelate different hexagonal and square cell phases to the symmetries of\nmaterials used for realizations of skyrmions. This will give clear directions\nfor experimental realizations of hexagonal and square cell phases, and will\nallow engineering of skyrmions with unusual properties. We also predict\nstriking differences in gyro-dynamics induced by spin currents for isolated\nskyrmions and for crystals where spin currents can be induced by charge\ncarriers or by thermal magnons. We find that under certain conditions, isolated\nskyrmions can move along the current without a side motion which can have\nimplications for realizations of magnetic memories.",
        "positive": "Field-driven skyrmion motion through velocity equipartition between\n  skyrmions and a domain wall: Magnetic skyrmions, as a whirling spin texture with axisymmetry, cannot be\npropelled by a uniform magnetic field. Therefore, reported skyrmion motions\nhave been induced using other sorts of stimuli; typically, electric currents in\nmagnetic metals as well as spin waves, thermal gradient, and field gradient\nhave manifested their ability to drive skyrmion motion. Here, we demonstrate,\nthrough micromagnetic simulations and analytically, that magnetic skyrmions can\nbe displaced by a uniform perpendicular magnetic field via a domain-wall (DW)\nmediator. For a fixed field strength, the velocity of a skyrmion train evolves\nin terms of 1 / (1 + Ns) with Ns denoting the number of skyrmions. Based on\nThiele's model, we reproduce the velocity-Ns relation first identified from\nnumerical results and reveal that the skyrmion-DW and inter-skyrmion repulsions\noffer the direct driving force for skyrmion motion. This study underlines the\nrole of spin textures' interaction in skyrmion dynamics, and opens an\nalternative route for skyrmion manipulation especially relevant to insulating\nmagnets. Given the correspondence between magnetism and electricity, we\nanticipate that the scheme should also work for polar skyrmions in\nferroelectrics."
    },
    {
        "anchor": "Anomalous Crystal Shapes of Topological Crystalline Insulators: Understanding crystal shapes is a fundamental subject in surface science. It\nis now well studied how chemical bondings determine crystal shapes via\ndependence of surface energies on surface orientations. Meanwhile, discoveries\nof topological materials have led us to a new paradigm in surface science, and\none can expect that topological surface states may affect surface energies and\ncrystal facets in an unconventional way. Here we show that the surface energy\nof glide-symmetric topological crystalline insulators (TCI) depends on the\nsurface orientation in a singular way via the parity of the Miller index. This\nsingular surface energy of the TCI affects equilibrium crystal shapes,\nresulting in emergence of unique crystal facets of the TCI. This singular\ndependence of the topological surface states is unique to the TCI protected by\nthe glide symmetry in contrast to a TCI protected by a mirror symmetry. In\naddition, we show that such singular surface states of the TCI protected by the\nglide symmetries can be realized in KHgSb with first-principles calculations.\nOur results provide a basis for designs and manipulations of crystal facets by\nutilizing symmetry and topology.",
        "positive": "Observation of nonreciprocal magnon Hanle effect: The precession of magnon pseudospin about the equilibrium pseudofield, the\nlatter capturing the nature of magnonic eigen-excitations in an\nantiferromagnet, gives rise to the magnon Hanle effect. Its realization via\nelectrically injected and detected spin transport in an antiferromagnetic\ninsulator demonstrates its high potential for devices and as a convenient probe\nfor magnon eigenmodes and the underlying spin interactions in the\nantiferromagnet. Here, we observe a nonreciprocity in the Hanle signal measured\nin hematite using two spatially separated platinum electrodes as spin\ninjector/detector. Interchanging their roles was found to alter the detected\nmagnon spin signal. The recorded difference depends on the applied magnetic\nfield and reverses sign when the signal passes its nominal maximum at the\nso-called compensation field. We explain these observations in terms of a spin\ntransport direction-dependent pseudofield. The latter leads to a\nnonreciprocity, which is found to be controllable via the applied magnetic\nfield. The observed nonreciprocal response in the readily available hematite\nfilms opens interesting opportunities for realizing exotic physics predicted so\nfar only for antiferromagnets with special crystal structures."
    },
    {
        "anchor": "Spinless composite fermions in an ultra-high quality strained Ge quantum\n  well: We report on an observation of a fractional quantum Hall effect in an\nultra-high quality two-dimensional hole gas hosted in a strained Ge quantum\nwell. The Hall resistance reveals precisely quantized plateaus and vanishing\nlongitudinal resistance at filling factors $\\nu = 2/3, 4/3$ and $5/3$. From the\ntemperature dependence around $\\nu = 3/2$ we obtain the composite fermion mass\nof $m^\\star \\approx 0.4\\,m_e$, where $m_e$ is the mass of a free electron.\nOwing to large Zeeman energy, all observed states are spin-polarized and can be\ndescribed in terms of spinless composite fermions.",
        "positive": "Coupling of Spin and Orbital Motion of Electrons in Carbon Nanotubes: Electrons in atoms possess both spin and orbital degrees of freedom. In\nnon-relativistic quantum mechanics, these are independent, resulting in large\ndegeneracies in atomic spectra. However, relativistic effects couple the spin\nand orbital motion leading to the well-known fine structure in their spectra.\nThe electronic states in defect-free carbon nanotubes (NTs) are widely believed\nto be four-fold degenerate, due to independent spin and orbital symmetries, and\nto also possess electron-hole symmetry. Here we report measurements\ndemonstrating that in clean NTs the spin and orbital motion of electrons are\ncoupled, thereby breaking all of these symmetries. This spin-orbit coupling is\ndirectly observed as a splitting of the four-fold degeneracy of a single\nelectron in ultra-clean quantum dots. The coupling favours parallel alignment\nof the orbital and spin magnetic moments for electrons and anti-parallel\nalignment for holes. Our measurements are consistent with recent theories that\npredict the existence of spin-orbit coupling in curved graphene and describe it\nas a spin-dependent topological phase in NTs. Our findings have important\nimplications for spin-based applications in carbon-based systems, entailing new\ndesign principles for the realization of qubits in NTs and providing a\nmechanism for all-electrical control of spins in NTs."
    },
    {
        "anchor": "Interaction-induced crossover between weak anti-localization and weak\n  localization in a disordered InAs/GaSb double quantum well: We present magneto-transport study in an InAs/GaSb double quantum well\nstructure in the weak localization regime. As the charge carriers are depleted\nusing a top gate electrode, we observe a crossover from weak anti-localization\n(WAL) to weak localization (WL), when the inelastic phase breaking time\ndecreases below spin-orbit characteristic time as a result of enhanced\nelectron-electron interactions at lower carrier concentrations. The same\ncrossover is observed with increasing temperature. The linear temperature\nbehavior of inelastic scattering rate indicates that the dominant phase\nbreaking mechanism in our 2D system is due to electron-electron interaction.",
        "positive": "Non-linear effects and dephasing in disordered electron systems: The calculation of the dephasing time in electron systems is presented. By\nmeans of the Keldysh formalism we discuss in a unifying way both weak\nlocalization and interaction effects in disordered systems. This allows us to\nshow how dephasing arises both in the particle-particle channel (weak\nlocalization) and in the particle-hole channel (interaction effect). First we\ndiscuss dephasing by an external field. Besides reviewing previous work on how\nan external oscillating field suppresses the weak localization correction, we\nderive a new expression for the effect of a field on the interaction\ncorrection. We find that the latter may be suppressed by a static electric\nfield, in contrast to weak localization. We then consider dephasing due to\ninelastic scattering. The ambiguities involved in the definition of the\ndephasing time are clarified by directly comparing the diagrammatic approach\nwith the path-integral approach. We show that different dephasing times appear\nin the particle-particle and particle-hole channels. Finally we comment on\nrecent experiments."
    },
    {
        "anchor": "Commensuration Effects in Layered Nanoparticle Solids: We have developed HiNTS, the {\\bf Hi}erarchical {\\bf N}anoparticle {\\bf\nT}ransport {\\bf S}imulator, and adapted it to study commensuration effects in\ntwo classes of Nanoparticle (NP) solids: (1) a bilayer NP solid (BNS) with an\nenergy offset, and (2) a BNS as part of a Field-Effect Transistor (FET). HiNTS\nintegrates the ab initio characterization of single NPs with the\nphonon-assisted tunneling transition model of the NP-NP transitions into a\nKinetic Monte Carlo based simulation of the charge transport in NP solids.\nFirst, we studied a BNS with an inter-layer energy offset $\\Delta$, possibly\ncaused by a fixed electric field. Our results include the following. (1) In the\nindependent energy-offset model, we observed the emergence of commensuration\neffects when scanning the electron filling factor $FF$ across integer values.\nThese commensuration effects were profound as they reduced the mobility by\nseveral orders of magnitude. We analyzed these commensuration effects in a five\ndimensional parameter space, as a function of the on-site charging energy\n$E_C$, energy offset $\\Delta$, the disorder $D$, the electron filling factor\n$FF$, and the temperature $k_{B}T$. We demonstrated the complexity of our model\nby showing that at integer filling factors $FF$ commensuration effects are\npresent in some regions of the parameter space, while they vanish in other\nregions, thus defining distinct dynamical phases of the model. We determined\nthe phase boundaries between these dynamical phases. (2) Using these results as\na foundation, we shifted our focus to the experimentally much-studied NP-FETs.\nNP-FETs are also characterized by an inter-layer energy offset $\\Delta$, which,\nin contrast to our first model, is set by the gate voltage $V_G$ and thereby\nrelated to the electron filling $FF$. We demonstrated the emergence of\ncommensuration effects and distinct dynamical phases in these NP-FETs.",
        "positive": "Klein tunneling of two correlated bosons: Reflection of two strongly interacting bosons with long-rage interaction\nhopping on a one-dimensional lattice scattered off by a potential step is\ntheoretically investigated in the framework of the extended Hubbard model. The\nanalysis shows that, in the presence of unbalanced on-site and nearest-neighbor\nsite interaction, two strongly correlated bosons forming a bound particle state\ncan penetrate a high barrier, despite the single particle can not. Such a\nphenomenon is analogous to one-dimensional Klein tunneling of a relativistic\nmassive Dirac particle across a potential step."
    },
    {
        "anchor": "Efficient terahertz emission from InAs nanowires: We observe intense pulses of far-infrared electromagnetic radiation emitted\nfrom arrays of InAs nanowires. The THz radiation power efficiency of these\nstructures is about 15 times higher compared to a planar InAs substrate. This\nis explained by the preferential orientation of coherent plasma motion to the\nwire surface, which overcomes radiation trapping by total-internal reflection.\nWe present evidence that this radiation originates from a low-energy acoustic\nsurface plasmon mode of the nanowire. This is supported by independent\nmeasurements of electronic transport on individual nanowires, ultrafast THz\nspectroscopy and theoretical analysis. Our combined experiments and analysis\nfurther indicate that these plasmon modes are specific to high aspect ratio\ngeometries.",
        "positive": "Time-evolution of the GaAs(0 0 1) pre-roughening process: The GaAs(0 0 1) surface is observed to evolve from being perfectly flat to a\nsurface half covered with one-monolayer high spontaneously formed GaAs islands.\nThe dynamics of this process are monitored with atomic-scale resolution using\nscanning tunneling microscopy. Surprisingly, pit formation dominates the early\nstages of island formation. Insight into the nucleation process is reported."
    },
    {
        "anchor": "Calculation of Elastic Strain Fields for Single Ge/Si Quantum Dots: An atomistic model based on the Keating potential and the conjugate gradient\nmethod are used for simulation of the strain fields for single Ge/Si quantum\ndots. Calculations are performed in the cluster approximation using clusters\ncontaining about three million atoms belonging to 150 coordination spheres. The\nspatial distributions of the strain energy density and electron potential\nenergy are calculated for different valleys forming the bottom of the silicon\nconduction band. It is shown that the strain field in silicon decreases\nsufficiently rapidly with distance from the center of the quantum dot, so the\ninfluence of the cluster boundary is observed only for very large quantum dots.",
        "positive": "Coherent charge carrier dynamics in the presence of thermal lattice\n  vibrations: We develop the coherent state representation of lattice vibrations to\ndescribe their interactions with charge carriers. In direct analogy to quantum\noptics, the coherent state representation leads from quantized lattice\nvibrations (phonons) naturally to a quasiclassical field limit, i.e., the\ndeformation potential. To an electron, the deformation field is a sea of hills\nand valleys, as ``real'' as any external field, morphing and propagating at the\nsound speed, and growing in magnitude with temperature. In this disordered\npotential landscape, the charge carrier dynamics is treated nonperturbatively,\npreserving their coherence beyond single collision events. We show the coherent\nstate picture agrees exactly with the conventional Fock state picture in\nperturbation theory. Furthermore, it goes beyond by revealing aspects that the\nconventional theory could not explain: transient localization even at high\ntemperatures by charge carrier coherence effects, and band tails in the density\nof states due to the self-generated disorder (deformation) potential in a pure\ncrystal. The coherent state paradigm of lattice vibrations supplies tools for\nprobing important questions in condensed matter physics as in quantum optics."
    },
    {
        "anchor": "Quantum Hall States in Graphene from Strain-Induced Nonuniform Magnetic\n  Fields: We examine strain-induced quantized Landau levels in graphene. Specifically,\narc-bend strains are found to cause nonuniform pseudomagnetic fields. Using an\neffective Dirac model which describes the low-energy physics around the nodal\npoints, we show that several of the key qualitative properties of graphene in a\nstrain-induced pseudomagnetic field are different compared to the case of an\nexternally applied physical magnetic field. We discuss how using different\nstrain strengths allows us to spatially separate the two components of the\npseudospinor on the different sublattices of graphene. These results are\nchecked against a tight-binding calculation on the graphene honeycomb lattice,\nwhich is found to exhibit all the features described. Furthermore, we find that\nintroducing a Hubbard repulsion on the mean-field level induces a measurable\npolarization difference between the A and the B sublattices, which provides an\nindependent experimental test of the theory presented here.",
        "positive": "The resistance of 2D Topological insulator in the absence of the\n  quantized transport: We report unconventional transport properties of HgTe wells with inverted\nband structure: the resistance does not show insulating behavior even when it\nis of the order of $10^2\\times h/2e^{2}$. The system is expected to be a\ntwo-dimensional topological insulator with a dominant edge state contribution.\nThe results are inconsistent with theoretical models developed within the\nframework of the helical Luttinger liquid."
    },
    {
        "anchor": "The root cause of hydrogen induced changes in optical transmission of\n  vanadium: The changes in the optical transmission of thin vanadium layers upon hydrogen\nabsorption are found to be dominated by the volume changes of the layers and\nnot directly linked to concentration. This effect is demonstrated by utilising\nthe difference in the hydrogen induced expansion of V layers in Fe/V and Cr/V\nsuperlattices. Hydrogen resides solely in the vanadium layers in these\nsuperlattices, while occupying different sites, causing different lattice\nexpansion. Quantitative agreement is obtained between the experimental results\nand first principle density functional calculations.",
        "positive": "Spontaneous spin polarization in doped semiconductor quantum wells: We calculate the critical density of the zero-temperature, first-order\nferromagnetic phase transition in n-doped GaAs/AlGaAs quantum wells. We find\nthat the existence of the ferromagnetic transition is dependent upon the choice\nof well width. We demonstrate rigorously that this dependence is governed by\nthe interplay between different components of the exchange interaction and that\nthere exists an upper limit for the well width beyond which there is no\ntransition. We predict that some narrow quantum wells could exhibit this\ntransition at electron densities lower than the ones that have been considered\nexperimentally thus far. We use a screened Hartree-Fock approximation with a\npolarization-dependent effective mass, which is adjusted to match the critical\ndensity predicted by Monte Carlo calculations for the two-dimensional electron\ngas."
    },
    {
        "anchor": "Magnetically stable zero-bias anomaly in Andreev contact to the magnetic\n  Weyl semimetal Co$_3$Sn$_2$S$_2$: Being encouraged by the interplay between topology, superconductivity and\nmagnetism, we experimentally investigate charge transport through the interface\nbetween the Nb superconductor and the time-reversal symmetry breaking Weyl\nsemimetal Co$_3$Sn$_2$S$_2$. In addition to the proximity induced\nsuperconducting gap, we observe several subgap features, among which the most\ninteresting is the prominent subgap zero-bias anomaly, absolutely stable\nagainst external magnetic fields up to the critical field of Nb. As the\npromising scenario for the zero-bias anomaly to appear in transport\ncharacteristics, we consider the proximity induced zero-energy Andreev bound\nstates interfaced with the half-metallic Co$_3$Sn$_2$S$_2$ and influenced by\nthe strong spin-orbit coupling and large Zeeman splitting.",
        "positive": "Quantum Interference Controlled Molecular Electronics: Quantum interference in coherent transport through single molecular rings may\nprovide a mechanism to control current in molecular electronics. We investigate\nits applicability by using a single-particle Green function method combined\nwith ab initio electronic structure calculations. We find that the quantum\ninterference effect (QIE) depends strongly on the interaction between molecular\npi states and contact sigma states. It is absent in small molecular rings with\nAu leads, such as benzene, due to strong pi-sigma hybridization, while it is\npreserved in large rings, such as [18]annulene, which then could be used to\nrealize QIE transistors."
    },
    {
        "anchor": "Transport signatures of pseudo-magnetic Landau levels in strained\n  graphene ribbons: In inhomogeneously strained graphene, low-energy electrons experience a\nvalley-antisymmetric pseudo-magnetic field which leads to the formation of\nlocalized states at the edge between the valence and conduction bands,\nunderstood in terms of peculiar n=0 pseudo-magnetic Landau levels. Here we show\nthat such states can manifest themselves as an isolated quadruplet of\nlow-energy conductance resonances in a suspended stretched graphene ribbon,\nwhere clamping by the metallic contacts results in a strong inhomogeneity of\nstrain near the ribbon ends.",
        "positive": "Remagnetization in the array of ferromagnetic nanowires with periodic\n  and quasiperiodic order: We investigate experimentally and theoretically the magnetization reversal\nprocess in one-dimensional magnonic structures composed of permalloy nanowires\nof the two different widths and finite length arranged in a periodic and\nquasiperiodic order. The main features of the hysteresis loop are determined by\ndifferent shape anisotropies of the component elements and the dipolar\ninteractions between them. We showed, that the dipolar interactions between\nnanowires forming a ribbon can be controlled by change a distance between the\nneighboring ribbons. The quasiperiodic order can influence the hysteresis loop\nby introduction additional tiny switching steps when the dipolar interactions\nare sufficiently strong."
    },
    {
        "anchor": "Photon-photon correlation statistics in the collective emission from\n  ensembles of self-assembled quantum dots: We present a theoretical analysis of the intensity autocorrelation for the\nspontaneous emission from a planar ensemble of self-assembled quantum dots.\nUsing the quantum jump approach, we numerically simulate the evolution of the\nsystem and construct photon-photon delay time statistics that approximates the\nsecond order correlation function of the field. The form of this correlation\nfunction in the case of collective emission from a highly homogeneous ensemble\nqualitatively differs form that characterizing an ensemble of independent\nemitters (inhomogeneous ensemble of uncoupled dots). The signatures of\ncollective emission in the intensity correlations are observed also in the case\nof an inhomogeneous but sufficiently strongly coupled ensemble. Thus, we show\nthat the second order correlation function of the emitted field provides a\nsensitive test of cooperative effects.",
        "positive": "Electronic transport in Si:P delta-doped wires: Despite the importance of Si:P delta-doped wires for modern nanoelectronics,\nthere are currently no computational models of electron transport in these\ndevices. In this paper we present a nonequilibrium Green's function model for\nelectronic transport in a delta-doped wire, which is described by a\ntight-binding Hamiltonian matrix within a single-band effective-mass\napproximation. We use this transport model to calculate the current-voltage\ncharacteristics of a number of delta-doped wires, achieving good agreement with\nexperiment. To motivate our transport model we have performed\ndensity-functional calculations for a variety of delta-doped wires, each with\ndifferent donor configurations. These calculations also allow us to accurately\ndefine the electronic extent of a delta-doped wire, which we find to be at\nleast 4.6 nm."
    },
    {
        "anchor": "Quantum electron transport controlled by cavity vacuum fields: We explore theoretically how the coupling to cavity vacuum fields affects the\nelectron transport in quantum conductors due to the counter-rotating-wave terms\nof light-matter interaction. We determine the quantum conductance in terms of\nthe transmission coefficients predicted by an effective electron Hamiltonian.\nThe coupling between bare electronic states is mediated by virtual processes\ninvolving intermediate states with one electron (or one hole) on top of the\nFermi sea and one virtual cavity photon. We study the behavior of the quantum\nconductance in the presence of artificial or disordered single-particle\npotentials, as well as a spatially varying cavity mode. As illustrative\nexamples, we apply our theory to 1D conductors and to disordered 2D quantum\nHall systems. We show how the cavity vacuum fields can lead to both large\nenhancement or suppression of electron conductance in the ballistic regime, as\nwell as modification of the conductance quantization and fluctuations.",
        "positive": "Direct determination of zero-field splitting for single Co$^{2+}$ ion\n  embedded in a CdTe/ZnTe quantum dot: When Co$^{2+}$ impurity is embedded in semiconductor structure, crystal\nstrain strongly influences zero-filed splitting between Co$^{2+}$ states with\nspin projection $S_z = \\pm 3/2$ and $S_z = \\pm 1/2$. Experimental evidences of\nthis effect have been given in previous studies, however direct measurement of\nthe strain induced zero-field splitting has been inaccessible so far. Here this\nsplitting is determined thanks to magneto-optical studies of individual\nCo$^{2+}$ ion in epitaxial CdTe quantum dot in ZnTe barrier. Using partially\nallowed optical transitions we measure strain induced zero-field splitting of\nCo$^{2+}$ ion directly on excitonic photoluminescence spectrum. Moreover, by\nobservation of anticrossing of $S_z = + 3/2$ and $S_z = - 1/2$ Co$^{2+}$ spin\nstates in magnetic field, we determine axial and in-plane components of crystal\nfield acting on Co$^{2+}$. Proposed technique can be applied for optical\ndetermination of zero-field splitting of other transition metal ions in quantum\ndots."
    },
    {
        "anchor": "Coulomb interacting Dirac fermions in disordered graphene: We study interacting Dirac quasiparticles in disordered graphene and find\nthat an interplay between the unscreened Coulomb interactions and\npseudo-relativistic quasiparticle kinematics can be best revealed in the\nballistic regime, whereas in the diffusive limit the behavior is qualitatively\n(albeit, not quantitatively) similar to that of the ordinary 2DEG with\nparabolic dispersion. We calculate the quasiparticle width and density of\nstates that can be probed by photoemission, tunneling, and magnetization\nmeasurements.",
        "positive": "Strongly anisotropic ballistic magnetoresistance in compact\n  three-dimensional semiconducting nanoarchitectures: We establish theoretically that in nonmagnetic semiconducting bilayer or\nmultilayer thin film systems rolled up into compact quasi-one-dimensional\nnanoarchitectures, the ballistic magnetoresistance is very anisotropic:\nconductances depend strongly on the direction of an externally applied magnetic\nfield. This phenomenon originates from the curved open geometry of rolled-up\nnanotubes, which leads to a tunability of the number of quasi-one-dimensional\nmagnetic subbands crossing the Fermi energy. The experimental significance of\nthis phenomenon is illustrated by a sizable anisotropy that scales with the\ninverse of the winding number, and persists up to a critical temperature that\ncan be strongly enhanced by increasing the strength of the external magnetic\nfield or the characteristic radius of curvature, and can reach room\ntemperature."
    },
    {
        "anchor": "Spin-Scattering Rates in Metallic Thin Films Measured by Ferromagnetic\n  Resonance Damping Enhanced by Spin-Pumping: We determined the spin-transport properties of Pd and Pt thin films by\nmeasuring the increase in ferromagnetic resonance damping due to spin-pumping\nin ferromagnetic (FM)-nonferromagnetic metal (NM) multilayers with varying NM\nthicknesses. The increase in damping with NM thickness depends strongly on both\nthe spin- and charge-transport properties of the NM, as modeled by diffusion\nequations that include both momentum- and spin-scattering parameters. We use\nthe analytical solution to the spin-diffusion equations to obtain\nspin-diffusion lengths for Pt and Pd. By measuring the dependence of\nconductivity on NM thickness, we correlate the charge- and spin-transport\nparameters, and validate the applicability of various models for\nmomentum-scattering and spin-scattering rates in these systems: constant,\ninverse-proportional (Dyakanov-Perel), and linear-proportional (Elliot-Yafet).\nWe confirm previous reports that the spin-scattering time can be shorter than\nthe momentum scattering time in Pt, and the Dyakanov-Perel-like model is the\nbest fit to the data.",
        "positive": "Monte Carlo Comparison of Quasielectron Wave Functions: Variational Monte Carlo calculations of the quasielectron and quasihole\nexcitation energies in the fractional quantum Hall effect have been carried out\nat filling fractions $\\nu=1/3$, 1/5, and 1/7. For the quasielectron both the\ntrial wave function originally proposed by Laughlin and the composite fermion\nwave function proposed by Jain have been used. We find that for long-range\nCoulomb interactions the results obtained using these two wave functions are\nessentially the same, though the energy gap obtained using the composite\nfermion quasielectron is slightly smaller, and closer to extrapolated\nexact-diagonalization results."
    },
    {
        "anchor": "Out of equilibrium charge dynamics in a hybrid cQED architecture: The recent development of hybrid cQED allows one to study how cavity photons\ninteract with a system driven out of equilibrium by fermionic reservoirs. We\nstudy here one of the simplest combination : a double quantum dot coupled to a\nsingle mode of the electromagnetic field. We are able to couple resonantly the\ncharge levels of a carbon nanotube based double dot to cavity photons. We\nperform a microwave read out of the charge states of this system which allows\nus to unveil features of the out of equilibrium charge dynamics, otherwise\ninvisible in the DC current. We extract relaxation rate, dephasing rate and\nphoton number of the hybrid system using a theory based on a master equation\ntechnique. These findings open the path for manipulating other degrees of\nfreedom e.g. the spin and/or the valley in nanotube based double dots using\nmicrowave light.",
        "positive": "Continuous Nucleation Dynamics of Magnetic Skyrmions in T-shaped\n  Helimagnetic Nanojunction: Magnetic skyrmions are topologically-protected spin textures existing in\nhelimagentic materials, which can be utilized as information carriers for\nnon-volatile memories and logic circuits in spintronics. Searching simple and\ncontrollable way to create isolated magnetic skyrmions is desirable for further\ntechnology developments and industrial designs. Based on micromagnetic\nsimulations, we show that the temporal dissipative structure can be developed\nin the T-shaped helimagnetic nanojunction when it is driven to the\nfar-from-equilibrium regime by a constant spin-polarized current. Then the\nmagnetic skyrmions can be continuously nucleated during the periodic\nmagnetization dynamics of the nanojunction. We have systematically investigated\nthe effects of current density, Dzyaloshinskii-Moriya interaction, external\nmagnetic field, and thermal fluctuation on the nucleation dynamics of the\nmagnetic skyrmions. Our results here suggest a novel and promising mechanism to\ncontinuously create magnetic skyrmions for the development of skyrmion-based\nspintronics devices."
    },
    {
        "anchor": "Magnetic Counting Rule of Radical Carbon Edge Nano Graphene: In order to explain room-temperature ferromagnetism of graphite-like\nmaterials, this paper offers a new magnetic counting rule of radical carbon\nzigzag edge nano graphene. Multiple spin state analysis based on a density\nfunction theory shows that the highest spin state is most stable. Energy\ndifference with next spin state overcomes kT=2000K suggesting a\nroom-temperature ferromagnetism. Local spin density at a radical carbon shows\ntwice a large up-spin cloud which comes from two orbital with tetrahedral\nconfiguration occupied by up-up spins. This leads a new magnetic counting rule\nto give a localized spin Sz=+2/2 to one radical carbon site, whereas Sz= -1/2\nto the nearest carbon site. Applied to five model molecules, we could confirm\nthis magnetic counting rule. In addition, we enhanced such concept to oxygen\nsubstituted zigzag edge occupied by four electrons.",
        "positive": "Strain effects on optical properties of tetrapod-shaped CdTe/CdS\n  core-shell nanocrystals: The exciton states of strained CdTe/CdS core-shell tetrapod-shaped\nnanocrystals were theoretically investigated by the numerical diagonalization\nof a configuration interaction Hamiltonian based on the single-band effective\nmass approximation. We found that the inclusion of strain promotes the type-II\nnature by confining the electrons and holes in nonadjacent regions. This\ncarrier separation is more efficient than that with type-II spherical\nnanocrystals. The strain leads to a small blue shift of the lowest exciton\nenergy. Its magnitude is smaller than the red shift induced by increasing the\nshell thickness. Moreover, the larger arm diameter reduces the influence of\nboth shell thickness and strain on the exciton energy. Considering the broken\nsymmetry, a randomness induced carrier separation was revealed which is unique\nto a branched core-shell structure. The calculated shell thickness dependence\nof the emission energy agrees well with available experimental data."
    },
    {
        "anchor": "Structural stability, electronic structure and optical properties of\n  dimension controlled self-assembled structures from clusters of cadmium\n  telluride: We report the first principle theory-based study of stability, electronic\nstructure and optical properties of cluster assembled materials in various 1D,\n2D and 3D nanostructures using a cage-like Cd9Te9 cluster as the super-atom.\nThe bulk 3D self-assemblies form in 2D stacked structures for different cubic\nlattices. The face centered stacking is the most stable as compared to the\nsimple cubic, body centered and zinc blende type stackings. The 2D stacks are\nformed as cluster assembled monolayers and the monolayer derived from the face\ncentered structure is most stable. Further, the cluster chains (or wires) with\nmore number of inter-cluster bonds are also seen to be dynamically stable. The\nelectronic structure, bandgap, dielectric constant and absorption spectra along\nwith the phonon dispersions are discussed for these self-assembled\nnanostructures.",
        "positive": "Strained topological insulator spin field effect transistor: The notion of a spin field effect transistor, where transistor action is\nrealized by manipulating the spin degree of freedom of charge carriers instead\nof the charge degree of freedom, has captivated researchers for at least three\ndecades. These transistors are usually implemented by modulating the spin orbit\ninteraction in a two- or one-dimensional semiconductor structure with an\nelectrostatic potential, which then causes controlled spin precession in the\ntransistor's channel that modulates the current flowing between two\nferromagnetic (spin-polarized) source and drain contacts. Here, we introduce a\nnew concept for a spin field effect transistor whose channel is made of a\nstrained topological insulator\n(strained-topological-insulator-field-effect-transistor or STI-SPINFET), which\ndoes not exploit spin-orbit interaction. Instead, the transistor function is\nelicited by straining the topological insulator (TI) with a gate voltage which\nmodifies the energy dispersion relation, or the Dirac velocity, to vary the\ninterference between the two spin eigenstates on the surface of the TI. This\nmodulates the current flowing between two ferromagnetic source and drain\ncontacts. The conductance on/off ratio of this transistor is too poor to be\nuseful as a switch, but it may have other uses, such as an extremely\nenergy-efficient stand-alone frequency multiplier."
    },
    {
        "anchor": "Probing the influence of dielectric environment on excitons in monolayer\n  WSe2: Insight from high magnetic fields: Excitons in atomically-thin semiconductors necessarily lie close to a\nsurface, and therefore their properties are expected to be strongly influenced\nby the surrounding dielectric environment. However, systematic studies\nexploring this role are challenging, in part because the most readily\naccessible exciton parameter -- the exciton's optical transition energy -- is\nlargely \\textit{un}affected by the surrounding medium. Here we show that the\nrole of the dielectric environment is revealed through its systematic influence\non the \\textit{size} of the exciton, which can be directly measured via the\ndiamagnetic shift of the exciton transition in high magnetic fields. Using\nexfoliated WSe$_2$ monolayers affixed to single-mode optical fibers, we tune\nthe surrounding dielectric environment by encapsulating the flakes with\ndifferent materials, and perform polarized low-temperature magneto-absorption\nstudies to 65~T. The systematic increase of the exciton's size with dielectric\nscreening, and concurrent reduction in binding energy (also inferred from these\nmeasurements), is quantitatively compared with leading theoretical models.\nThese results demonstrate how exciton properties can be tuned in future 2D\noptoelectronic devices.",
        "positive": "Quantum Simulation of the Hubbard Model with Dopant Atoms in Silicon: In quantum simulation, many-body phenomena are probed in controllable quantum\nsystems. Recently, simulation of Bose-Hubbard Hamiltonians using cold atoms\nrevealed previously hidden local correlations. However, fermionic many-body\nHubbard phenomena such as unconventional superconductivity and spin liquids are\nmore difficult to simulate using cold atoms. To date the required single-site\nmeasurements and cooling remain problematic, while only ensemble measurements\nhave been achieved. Here we simulate a two-site Hubbard Hamiltonian at low\neffective temperatures with single-site resolution using subsurface dopants in\nsilicon. We measure quasiparticle tunneling maps of spin-resolved states with\natomic resolution, finding interference processes from which the entanglement\nentropy and Hubbard interactions are quantified. Entanglement, determined by\nspin and orbital degrees of freedom, increases with increasing covalent bond\nlength. We find separation-tunable Hubbard interaction strengths that are\nsuitable for simulating strongly correlated phenomena in larger arrays of\ndopants, establishing dopants as a platform for quantum simulation of the\nHubbard model."
    },
    {
        "anchor": "The loop-zag resonator: A loop-gap resonator design for improved\n  sensitivity in electron-spin resonance experiments: We present a novel design of loop-gap resonator, the loop-zag resonator, for\nsub-X-band electron-spin resonance spectroscopy. The loop-zag design can\nachieve improved coupling to small-sample spin systems through the improvement\nof sample filling factor and RF $B_1$ field. By introducing ``zags'' to the\nresonator's gap path, the capacitance is increased, accommodating a smaller\nloop size and thereby a larger filling factor to maintain the requisite\nresonant frequency. We present experimental spectra on five different\nresonators, each with approximately the same resonant frequency of\n$\\sim2.9$~GHz, showing that an increase in the number of zags and reduction in\nloop size gives rise to higher sensitivity. Finite-element simulations of these\nresonators provide estimates of the improved filling factors obtained through\nthe addition of zags. The frequency range over which this loop-zag design is\npractical enables a breadth of future applications in microwave engineering,\nincluding ESR and ESR-like quantum information microwave techniques.",
        "positive": "Charge dynamics and spin blockade in a hybrid double quantum dot in\n  silicon: Electron spin qubits in silicon, whether in quantum dots or in donor atoms,\nhave long been considered attractive qubits for the implementation of a quantum\ncomputer due to the semiconductor vacuum character of silicon and its\ncompatibility with the microelectronics industry. While donor electron spins in\nsilicon provide extremely long coherence times and access to the nuclear spin\nvia the hyperfine interaction, quantum dots have the complementary advantages\nof fast electrical operations, tunability and scalability. Here we present an\napproach to a novel hybrid double quantum dot by coupling a donor to a\nlithographically patterned artificial atom. Using gate-based rf reflectometry,\nwe probe the charge stability of this double quantum dot system and the\nvariation of quantum capacitance at the interdot charge transition. Using\nmicrowave spectroscopy, we find a tunnel coupling of 2.7 GHz and characterise\nthe charge dynamics, which reveals a charge T2* of 200 ps and a relaxation time\nT1 of 100 ns. Additionally, we demonstrate spin blockade at the inderdot\ntransition, opening up the possibility to operate this coupled system as a\nsinglet-triplet qubit or to transfer a coherent spin state between the quantum\ndot and the donor electron and nucleus."
    },
    {
        "anchor": "A twisted conformal field theory description of the Quantum Hall Effect: We construct an effective conformal field theory by using a procedure which\ninduces twisted boundary conditions for the fundamental scalar fields. That\nallows to describe a quantum Hall fluid at Jain hierarchical filling,\nnu=m/(2pm+1), in terms of one charged scalar field and m-1 neutral ones. Then\nthe resulting algebra of the chiral primary fields is U(1)xW_m. Finally the\nground state wave functions are given as correlators of appropriate composite\nfields (a-electrons).",
        "positive": "Reply to Comment on `Theory of microwave-induced zero-resistance states\n  in two-dimensional electron systems' and on `Microwave-induced\n  zero-resistance states and second-harmonic generation in an ultraclean\n  two-dimensional electron gas': We show that all questions raised in the Comment can be easily answered\nwithin the theory formulated in the commented papers. It is also shown that the\nbulk theory promoted by the commenter fails to explain the most important\nfundamental features of the discussed phenomenon."
    },
    {
        "anchor": "Topological Protection from Random Rashba Spin-Orbit Backscattering:\n  Ballistic Transport in a Helical Luttinger Liquid: The combination of Rashba spin-orbit coupling and potential disorder induces\na random current operator for the edge states of a 2D topological insulator. We\nprove that charge transport through such an edge is ballistic at any\ntemperature, with or without Luttinger liquid interactions. The solution\nexploits a mapping to a spin 1/2 in a time-dependent field that preserves the\nprojection along one randomly undulating component (integrable dynamics). Our\nresult is exact and rules out random Rashba backscattering as a source of\ntemperature-dependent transport, absent integrability-breaking terms.",
        "positive": "Transport and quantum coherence in graphene rings: Aharonov-Bohm\n  oscillations, Klein tunneling and particle localization: Simulating quantum transport through mesoscopic, ring-shaped graphene\nstructures, we address various quantum coherence and interference phenomena.\nFirst, a perpendicular magnetic field, penetrating the graphene ring, gives\nrise to Aharonov-Bohm oscillations in the conductance as a function of the\nmagnetic flux, on top of the universal conductance fluctuations. At very high\nfluxes the interference gets suppressed and quantum Hall edge channels develop.\nSecond, applying an electrostatic potential to one of the ring arms, $nn'n$- or\n$npn$-junctions can be realized with particle transmission due to normal\ntunneling or Klein tunneling. In the latter case the Aharonov-Bohm oscillations\nweaken for smooth barriers. Third, if potential disorder comes in to play, both\nAharonov-Bohm and Klein tunneling effects rate down, up to the point where\nparticle localization sets in."
    },
    {
        "anchor": "Temperature dependence of the visibility in an electronic Mach-Zehnder\n  interferometer: We performed the conductance and the shot noise measurements in an electronic\nMach-Zehnder interferometer. The visibility of the interference is investigated\nas a function of the electron temperature that is derived from the thermal\nnoise of the interferometer. The non-equilibrium noise displays both h/e and\nh/2e oscillations vs. the modulation gate voltage.",
        "positive": "Photo-spintronics of spin-orbit active electric weak links: We show that a carbon nanotube can serve as a functional electric weak link\nperforming photo-spintronic transduction. A spin current, facilitated by strong\nspin-orbit interactions in the nanotube and not accompanied by a charge\ncurrent, is induced in a device containing the nanotube weak link by circularly\npolarized microwaves. Nanomechanical tuning of the photo-spintronic\ntransduction can be achieved due to the sensitivity of the spin-orbit\ninteraction to geometrical deformations of the weak link."
    },
    {
        "anchor": "Polarization-entangled twin photons from two-photon quantum-dot emission: Semiconductor quantum dots are promising sources for polarization-entangled\nphotons. As an alternative to the usual cascaded biexciton-exciton emission,\ndirect two-photon emission from the biexciton can be used. With a high-quality\noptical resonator tuned to half the biexciton energy, a large proportion of the\nphotons can be steered into the two-photon emission channel. In this case the\ndegree of polarization entanglement is inherently insensitive to the exciton\nfine-structure splitting. In the present work we analyze the biexciton emission\nwith particular emphasis on the influence of coupling of the quantum-dot cavity\nsystem to its environment. Especially for a high-quality cavity, the coupling\nto the surrounding semiconductor material can open up additional\nphonon-assisted decay channels. Our analysis demonstrates that with the cavity\ntuned to half the biexciton energy, the potentially detrimental influence of\nthe phonons on the polarization entanglement is strongly suppressed -- high\ndegrees of entanglement can still be achieved. We further discuss spectral\nproperties and statistics of the emitted twin photons.",
        "positive": "Large enhancement of Edelstein effect in Weyl semimetals from Fermi-arc\n  surface states: One remarkable feature of Weyl semimetals is the manifestation of their\ntopological nature in the form of the Fermi-arc surface states. In a recent\ncalculation by \\cite{Johansson2018}, the current-induced spin polarization or\nEdelstein effect has been predicted, within the semiclassical Boltzmann theory,\nto be strongly amplified in a Weyl semimetal TaAs due to the existence of the\nFermi arcs. Motivated by this result, we calculate the Edelstein response of an\neffective model for an inversion-symmetry-breaking Weyl semimetal in the\npresence of an interface using linear response theory. The scatterings from\nscalar impurities are included and the vertex corrections are computed within\nthe self-consistent ladder approximation. At chemical potentials close to the\nWeyl points, we find the surface states have a much stronger response near the\ninterface than the bulk states by about one to two orders of magnitude. At\nhigher chemical potentials, the surface states' response near the interface\ndecreases to be about the same order of magnitude as the bulk states' response.\nWe attribute this phenomenon to the decoupling between the Fermi arc states and\nbulk states at energies close to the Weyl points. The surface states which are\neffectively dispersing like a one-dimensional chiral fermion become nearly\nnondissipative. This leads to a large surface vertex correction and, hence, a\nstrong enhancement of the surface states' Edelstein response."
    },
    {
        "anchor": "Memristive and tunneling effects in 3D interconnected silver nanowires: Due to their memristive properties nanowire networks are very promising for\nneuromorphic computing applications. Indeed, the resistance of such systems can\nevolve with the input voltage or current as it confers a synaptic behaviour to\nthe device. Here, we propose a network of silver nanowires (Ag-NWs) which are\ngrown in a nanopourous membrane with interconnected nanopores by\nelectrodeposition. This bottom-up approach fabrication method gives a\nconducting network with a 3D architecture and a high density of Ag-NWs. The\nresulting 3D interconnected Ag-NW network exhibits a high initial resistance as\nwell as a memristive behavior. It is expected to arise from the creation and\nthe destruction of conducting silver filaments inside the Ag-NW network.\nMoreover, after several cycles of measurement, the resistance of the network\nswitches from a high resistance regime, in the GOhm range, with a tunnel\nconduction to a low resistance regime, in the kOhm range.",
        "positive": "Energy Spectrum of Neutral Collective Excitations in Striped Hall States: We investigate neutral collective excitations in the striped Hall state. In\nthe striped Hall state, the magnetic translation and rotation symmetries are\nspontaneously broken. Using the commutation relation between charges and\ncurrents corresponding to the broken and unbroken symmetry, the existence of\nthe gapless neutral excitation is proved. The spectrum of the neutral\ncollective excitation at the half-filled third Landau level is obtained in the\nsingle mode approximation. We find the periodic line nodes in the spectrum. The\nspectrum is compared with the particle-hole excitation spectrum in the\nHartree-Fock approximation."
    },
    {
        "anchor": "Broadband photoresponse arising from photo-bolometric effect in\n  quasi-one-dimensional Ta2Ni3Se8: In this paper, we report the synthesis of high-quality Ta2Ni3Se8 crystals\nfree of noble or toxic elements and the fabrication and testing of\nphotodetectors on the wire samples. A broadband photoresponse from 405 nm to\n1550 nm is observed, along with performance parameters including relatively\nhigh photoresponsivity (10 mA W^-1) and specific detectivity (3.5 * 10^7 Jones)\nand comparably short response time ({\\tau}_rise = 433 ms, {\\tau}_decay = 372\nms) for 1064 nm, 0.5 V bias and 1.352 mW mm^-2. Through extensive measurement\nand analysis, it is determined that the dominant mechanism for photocurrent\ngeneration is the photo-bolometric effect, which is believed to be responsible\nfor the very broad spectral detection capability. More importantly, the\npronounced response to 1310 nm and 1550 nm wavelengths manifests its promising\napplications in optical communications. Considering the quasi-one-dimensional\nstructure with layered texture, the potential to build nanodevices on Ta2Ni3Se8\nmakes it even more important in future electronic and optoelectronic\napplications.",
        "positive": "Unconventional Filling Factor 4/11: A Closed-Form Ground State Wave\n  Function: The ground state at 4/11 filling factor is very well understood [Phys. Rev.\nLett. 112, 016801 (2014)] in terms of the 1/3 filled second effective Landau\nlevel of the composite fermions whose correlations resemble with that of\nelectrons in the ground state of two-body Haldane pseudo-potential of relative\nangular momentum 3, $V_3$. We here propose a closed-form ground state wave\nfunction for $V_3$ at 1/3 filling factor. We successfully compare it with the\nexact wave function for the systems with a few electrons, by calculating their\nmutual overlap, pair-correlation function, and entanglement spectra. By\nnumerical exact diagonalization for a few electron systems, we find a window of\nnonzero $V_3$ is essential together with $V_1$ for being 4/11 state\nincompressible. The constructed wave function for 4/11 state using this\nproposed wave function has satisfactorily high overlap with the previously\nstudied composite-fermion-diagonalized ground state wave function."
    },
    {
        "anchor": "Bound states in the continuum in graphene quantum dot structures: The existence of bound states in the continuum was predicted at the dawn of\nquantum mechanics by von Neumann and Wigner. In this work we discuss the\nmechanism of formation of these exotic states and the feasibility to observe\nthem experimentally in symmetrical heterostructures composed by segments of\ngraphene ribbons with different widths forming a graphene quantum dot. We\nidentify the existence of bound states in the continuum in these graphene\nquantum dot systems by means of local density of states and electronic\nconductance calculations.",
        "positive": "Weak localization in transition metal dichalcogenide monolayers and\n  their heterostructures with graphene: We calculate the interference correction to the conductivity of doped\ntransition metal dichalcogenide (TMDC) monolayers. Because of the interplay\nbetween valley structure and intrinsic spin-orbit coupling (SOC), these\nmaterials exhibit a rich weak localization (WL) behavior that is qualitatively\ndifferent from conventional metals or similar two-dimensional materials such as\ngraphene. Our results can also be used to describe graphene/TMDC\nheterostructures, where the SOC is induced in the graphene sheet. We discuss\nnew parameter regimes that go beyond existing theories, and can be used to\ninterpret recent experiments in order to assess the strength of SOC and\ndisorder. Furthermore, we show that an in-plane Zeeman field can be used to\ndistinguish the contributions of different kinds of SOC to the WL\nmagnetoconductance."
    },
    {
        "anchor": "Spin-motive force due to domain wall motion in the presence of\n  Dzyaloshinskii-Moriya Interaction: We theoretically demonstrate that the presence of Dzyaloshinskii-Moriya\nInteraction (DMI) can lead to enhancement of the spin-motive force (SMF)\narising due to field-induced ferromagnetic domain wall motion. A SMF refers to\nan electric voltage induced by dynamical magnetic textures, which reflects the\ntemporal and spatial variations of the magnetization. A DMI can introduce extra\nspatial rotation of the magnetization in the domain wall region, which turns\nout to cause the enhancement of the SMF. We derive an expression for the SMF,\nand examine the field- and DMI-dependences of the SMF. We find that the SMF can\nbe amplified by up to an order of magnitude in the low field regime, where the\nexternal field is lower than the so-called Walker breakdown field.",
        "positive": "Theory of tunneling conductance of graphene NIS junctions: We calculate the tunneling conductance of a graphene normal\nmetal-insulator-superconductor (NIS) junction with a barrier of thickness $d$\nand with an arbitrary voltage $V_0$ applied across the barrier region. We\ndemonstrate that the tunneling conductance of such a NIS junction is an\noscillatory function of both $d$ and $V_0$. We also show that the periodicity\nand amplitude of such oscillations deviate from their universal values in the\nthin barrier limit as obtained in earlier work [Phys. Rev. Lett. {\\bf 97},\n217001 (2006)] and become a function of the applied voltage $V_0$. Our results\nreproduces the earlier results on tunneling conductance of such junctions in\nthe thin [Phys. Rev. Lett. {\\bf 97}, 217001 (2006)] and zero [Phys. Rev. Lett.\n{\\bf 97}, 067007 (2006)] barrier limits as special limiting cases. We discuss\nexperimental relevance of our results."
    },
    {
        "anchor": "Coexistent State of Charge Density Wave and Spin Density Wave in\n  One-Dimensional Quarter Filled Band Systems under Magnetic Fields: We theoretically study how the coexistent state of the charge density wave\nand the spin density wave in the one-dimensional quarter filled band is\nenhanced by magnetic fields. We found that when the correlation between\nelectrons is strong the spin density wave state is suppressed under high\nmagnetic fields, whereas the charge density wave state still remains. This will\nbe observed in experiments such as the X-ray measurement.",
        "positive": "High magnetoresistance at room temperature in p-i-n graphene nanoribbons\n  due to band-to-band tunneling effects: A large magnetoresistance effect is obtained at room-temperature by using\np-i-n armchair-graphene-nanoribbon (GNR) heterostructures. The key advantage is\nthe virtual elimination of thermal currents due to the presence of band gaps in\nthe contacts. The current at B=0T is greatly decreased while the current at\nB>0T is relatively large due to the band-to-band tunneling effects, resulting\nin a high magnetoresistance ratio, even at room-temperature. Moreover, we\nexplore the effects of edge-roughness, length, and width of GNR channels on\ndevice performance. An increase in edge-roughness and channel length enhances\nthe magnetoresistance ratio while increased channel width can reduce the\noperating bias."
    },
    {
        "anchor": "Amorphous topological insulators constructed from random point sets: The discovery that the band structure of electronic insulators may be\ntopologically non-trivial has unveiled distinct phases of electronic matter\nwith novel properties. Recently, mechanical lattices have been found to have\nsimilarly rich structure in their phononic excitations, giving rise to\nprotected uni-directional edge modes whose existence was demonstrated in\nlattices of interacting gyroscopes and coupled pendula. In all these cases,\nhowever, as well as in other topological metamaterials, the underlying\nstructure was finely tuned, be it through periodicity, quasi-periodicity or\nisostaticity. Here we show that amorphous mechanical Chern insulators\nconsisting of interacting gyroscopes can be readily constructed from arbitrary\nunderlying structures, including hyperuniform, jammed, quasi-crystalline, and\nuniformly random point sets. While our findings apply to mechanical and\nelectronic systems alike, we focus on networks of interacting gyroscopes as a\nmodel system. Local decoration control the topology of the vibrational\nspectrum, endowing amorphous structures with protecting edge modes -- with a\nchirality of choice. Using a real-space generalization of the Chern number, we\ninvestigate the topology of our structures numerically, analytically and\nexperimentally. The robustness of our approach enables the topological design\nand self-assembly of non-crystalline topological metamaterials on the micro and\nmacro scale.",
        "positive": "Near-field heat transfer between multilayer hyperbolic metamaterials: We review the near-field radiative heat flux between hyperbolic materials\nfocusing on multilayer hyperbolic meta-materials. We discuss the formation of\nthe hyperbolic bands, the impact of ordering of the multilayer slabs, as well\nas the impact of the first single layer on the heat transfer. Furthermore, we\ncompare the contribution of surface modes to that of hyperbolic modes. Finally,\nwe also compare the exact results with predictions from effective medium\ntheory."
    },
    {
        "anchor": "Coherent magnetotransport and time-dependent transport through\n  split-gated quantum constrictions: The authors report on modeling of transport spectroscopy in split-gate\ncontrolled quantum constrictions. A mixed momentum-coordinate representation is\nemployed to solve a set of time-dependent Lippmann-Schwinger equations with\nintricate coupling between the subbands and the sidebands. Our numerical\nresults show that the transport properties are tunable by adjusting the\nac-biased split-gates and the applied perpendicular magnetic field. We\nillustrate time-modulated quasibound-state features involving inter-sideband\ntransitions and the Aharonov-Bohm oscillation characteristics in the\nsplit-gated systems.",
        "positive": "Transport signatures of a quantum spin Hall - chiral topological\n  superconductor junction: We investigate transport through a normal-superconductor (NS) junction made\nfrom a quantum spin Hall (QSH) system with helical edge states and a\ntwo-dimensional (2D) chiral topological superconductor (TSC) having a chiral\nMajorana edge mode. We employ a two-dimensional extended four-band model for\nHgTe-based quantum wells in a magnetic (Zeeman) field and subject to s-wave\nsuperconductivity. We show using the Bogoliubov-de Gennes scattering formalism\nthat this structure provides a striking transport signal of a 2D TSC. As a\nfunction of the sample width (or Fermi energy) the conductance resonances go\nthrough a sequence of $2e^2/h$ (non-trivial phase) and $4e^2/h$ plateaux\n(trivial phase) which fall within the region of a non-zero Chern number (2D\nlimit) as the sample width becomes large. These signatures are a manifestation\nof the topological nature of the QSH effect and the TSC."
    },
    {
        "anchor": "Cooling of chiral heat transport in the quantum Hall effect graphene: In the quantum Hall effect (QHE) regime, heat is carried by electrons in the\nedge states of Landau levels. Here, we study cooling of hot electrons\npropagating along the edge of graphene at the filling factor $\\nu=\\pm2$,\nmediated by acoustic phonons. We determine the temperature profile extended\nfrom a hot spot, where the Hall current is injected into graphene from a\nmetallic contact, taking into account specifics of boundary conditions for\nlattice displacements in graphene in a van der Waals heterostructure with an\ninsulating substrate. Our calculations, performed using generic boundary\nconditions for Dirac electrons, show that emission of phonons can explain a\nshort cooling length observed in graphene-based QHE devices by Nahm, Hwang and\nLee [PRL 110, 226801 (2013)].",
        "positive": "Topologically non-trivial magnon bands in artificial square spin ices\n  subject to Dzyaloshinskii-Moriya interaction: Systems that exhibit topologically protected edge states are interesting both\nfrom a fundamental point of view as well as for potential applications, the\nlatter because of the absence of back-scattering and robustness to\nperturbations. It is desirable to be able to control and manipulate such edge\nstates. Here, we show that artificial square ices can incorporate both\nfeatures: an interfacial Dzyaloshinksii-Moriya gives rise to topologically\nnon-trivial magnon bands, and the equilibrium state of the spin ice is\nreconfigurable with different configurations having different magnon\ndispersions and topology. The topology is found to develop as odd-symmetry bulk\nand edge magnon bands approach each other, so that constructive band inversion\noccurs in reciprocal space. Our results show that topologically protected bands\nare supported in square spin ices."
    },
    {
        "anchor": "Symmetry-broken Chern insulators in twisted double bilayer graphene: Twisted double bilayer graphene (tDBG) has emerged as an especially rich\nplatform for studying strongly correlated and topological states of matter. The\nmaterial features moir\\'e bands that can be continuously deformed by both\nperpendicular displacement field and twist angle. Here, we construct a phase\ndiagram representing of the correlated and topological states as a function of\nthese parameters, based on measurements on over a dozen tDBG devices\nencompassing the two distinct stacking configurations in which the constituent\nBernal bilayer graphene sheets are rotated either slightly away from 0{\\deg} or\n60{\\deg}. We find a hierarchy of symmetry-broken states that emerge\nsequentially as the twist angle approaches an apparent optimal value of $\\theta\n\\approx$ 1.34{\\deg}. Among them, we discover a sequence of symmetry-broken\nChern insulator (SBCI) states that arise only within a narrow range of twist\nangles ($\\approx$ 1.33{\\deg} to 1.39{\\deg}). We observe an associated anomalous\nHall effect at zero field in all samples supporting SBCI states, indicating\nspontaneous time-reversal symmetry breaking and possible moir\\'e unit cell\nenlargement at zero magnetic field.",
        "positive": "Bimerons in Double Layer Quantum Hall Systems: In this paper we discuss bimeron pseudo spin textures for double layer\nquantum hall systems with filling factor $\\nu =1$. Bimerons are excitations\ncorresponding to bound pairs of merons and anti-merons.\n  Bimeron solutions have already been studied at great length by other groups\nby minimising the microsopic Hamiltonian between microscopic trial\nwavefunctions. Here we calculate them by numerically solving coupled nonlinear\npartial differential equations arising from extremisation of the effective\naction for pseudospin textures. We also calculate the different contributions\nto the energy of our bimerons, coming from pseudospin stiffness, capacitance\nand coulomb interactions between the merons. Apart from augmenting earlier\nresults, this allows us to check how good an approximation it is to think of\nthe bimeron as a pair of rigid objects (merons) with logarithmically growing\nenergy, and with electric charge ${1 \\over 2}$. Our differential equation\napproach also allows us to study the dependence of the spin texture as a\nfunction of the distance between merons, and the inter layer distance. Lastly,\nthe technical problem of solving coupled nonlinear partial differential\nequations, subject to the special boundary conditions of bimerons is\ninteresting in its own right."
    },
    {
        "anchor": "Quantum nanoconstrictions fabricated by cryo-etching in encapsulated\n  graphene: More than a decade after the discovery of graphene, ballistic transport in\nnanostructures based on this intriguing material still represents a challenging\nfield of research in two-dimensional electronics. The presence of rough edges\nin nanostructures based on this material prevents the appearance of truly\nballistic electron transport as theo\\-re\\-tically predicted and, therefore, not\nwell-developed plateaus of conductance have been revealed to date. In this work\nwe report on a novel implementation of the cryo-etching method, which enabled\nus to fabricate graphene nanoconstrictions encapsulated between hexagonal boron\nnitride thin films with unprecedented control of the structure edges. High\nquality smooth nanometer-rough edges are characterized by atomic force\nmicroscopy and a clear correlation between low roughness and the existence of\nwell-developed quantized conductance steps with the concomitant occurrence of\nballistic transport is found at low temperature. In par\\-ti\\-cu\\-lar, we come\nupon exact 2$e^{2}/h$ quantization steps of conductance at zero magnetic field\ndue to size quantization, as it has been theoretically predicted for truly\nballistic electron transport through graphene nanoconstrictions.",
        "positive": "Thermal rectification in a double quantum dots system with polaron\n  effect: We investigate the rectification of heat current carried by electrons through\na double quantum dot (DQD) system under a temperature bias. The DQD can be\nrealized by molecules such as suspended carbon nanotube and be described by the\nAnderson-Holstein model in presence of electron-phonon interaction. Strong\nelectron-phonon interaction can lead to formation of polaronic states in which\nelectronic states are dressed by phonon cloud. Dressed tunneling approximation\n(DTA), which is nonperturbative in dealing with strong electron-phonon\ninteraction, is employed to obtain the heat current expression. In DTA,\nself-energies are dressed by phonon cloud operator and are temperature\ndependent. The temperature dependency of imaginary part of dressed retarded\nself-energy gives rise to the asymmetry of the system and is the necessary\ncondition of thermal rectification. On top of this, one can either tune DQD\neffective energy levels such that $|\\bar{\\epsilon}_1|\\neq |\\bar{\\epsilon}_2|$\nor have asymmetric dot-lead couplings to achieve thermal rectification. We\nnumerically find that increasing electron-phonon coupling and reducing inter\ndot coupling can both improve thermal rectification effect, while the\nelectronic heat current is reduced."
    },
    {
        "anchor": "Large linear magnetoresistance from neutral defects in Bi$_2$Se$_3$: The chalcogenide Bi$_2$Se$_3$ can attain the three dimensional (3D) Dirac\nsemimetal state under the influence of strain and microstrain. Here we report\nthe presnece of large linear magnetoresistance in such a Bi$_2$Se$_3$ crystal.\nThe magnetoresistance has quadratic form at low fields which crossovers to\nlinear above 4 T. The temperature dependence of magnetoresistance scales with\ncarrier mobility and the crossover field scales with inverse of mobility. Our\nanalysis suggest that the linear magnetoresistance in our system has a\nclassical origin and arises from the scattering of high mobility 3D Dirac\nelectrons from crystalline inhomogeneities. We observe that the charged\nselenium vacancies are strongly screened by high mobility Dirac electrons and\nthe neutral crystalline defects are the main scattering center for transport\nmechanism. Our analysis suggests that both the resistivity and the\nmagnetoresistance have their origin in scattering of charge carriers from\nneutral defects.",
        "positive": "Advanced method for reliable estimation of the spin-orbit torque\n  efficiency in low coercive ferromagnetic multilayers: An experimental study of current-induced magnetization reversal of the\nRu/Co/Ru and Ru/Co/Ru/W structures was carried out. In the considered\nstructures, due to the small value of the coercive force comparable in\nmagnitude to the Oersted field and the SOT effect field, magnetization reversal\nis carried out by moving a domain wall parallel to the direction of current\ninjection. For such a case, a new method for estimating the effective field of\nSOT based on the analysis of the domain wall position taking into account the\ndistribution of the Oersted field was proposed. This method allowed determining\nthe effective longitudinal field and the efficiency of SOT equal 0.03 in the\nquasi-symmetric Ru/Co/Ru structure. It was found that adding the W capping\nlayer enhances the SOT effect by 5 times."
    },
    {
        "anchor": "Cavity quantum electrodynamics with semiconductor double-dot molecules\n  on a chip: We describe a coherent control technique for coupling electron spin states\nassociated with semiconductor double-dot molecule to a microwave stripline\nresonator on a chip. We identify a novel regime of operation in which strong\ninteraction between a molecule and a resonator can be achieved with minimal\ndecoherence, reaching the so-called strong coupling regime of cavity QED. We\ndescribe potential applications of such a system, including low-noise coherent\nelectrical control, fast QND measurements of spin states, and long-range spin\ncoupling.",
        "positive": "Exciton-photon correlations in bosonic condensates of exciton-polaritons: Exciton-polaritons are mixed light-matter quasiparticles. We have developed a\nstatistical model describing stochastic exciton-photon transitions within a\ncondensate of exciton polaritons. We show that the exciton-photon correlator\ndepends on the \"hidden variable\" which characterizes the rate of exciton-photon\ntransformations in the condensate. We discuss implications of this effect for\nthe quantum statistics of photons emitted by polariton lasers."
    },
    {
        "anchor": "Detecting and Distinguishing Majorana Zero Modes with the Scanning\n  Tunneling Microscope: The goal of creating topologically protected qubits using non-Abelian anyons\nis currently one of the most exciting areas of research in quantum condensed\nmatter physics. Majorana zero modes (MZM), which are non-Abelian anyons\npredicted to emerge as localized zero energy states at the ends of\none-dimensional topological superconductors, have been the focus of these\nefforts. In the search for experimental signatures of these novel\nquasi-particles in different material platforms, the scanning tunneling\nmicroscope (STM) has played a key role. The power of high-resolution STM\ntechniques is perhaps best illustrated by their application in identifying MZM\nin one-dimensional chains of magnetic atoms on the surface of a superconductor.\nIn this platform, STM spectroscopic mapping has demonstrated the localized\nnature of MZM zero-energy excitations at the ends of such chains, while\nexperiments with superconducting and magnetic STM tips have been used to\nuniquely distinguish them from trivial edge modes. Beyond the atomic chains,\nSTM has also uncovered signatures of MZM in two-dimensional materials and\ntopological surface and boundary states, when they are subjected to the\nsuperconducting proximity effect. Looking ahead, future STM experiments can\nadvance our understanding of MZM and their potential for creating topological\nqubits, by exploring avenues to demonstrate their non-Abelian statistics.",
        "positive": "A Physics-based Analytical Model for Perovskite Solar Cells: Perovskites are promising next-generation absorber materials for low-cost and\nhigh-efficiency solar cells. Although perovskite cells are configured similar\nto the classical solar cells, their operation is unique and requires\ndevelopment of a new physical model for characterization, optimization of the\ncells, and prediction of the panel performance. In this paper, we develop such\na physics-based analytical model to describe the operation of different types\nof perovskite solar cells, explicitly accounting non-uniform generation,\ncarrier selective transport layers, and voltage-dependent carrier collection.\nThe model would allow experimentalists to characterize key parameters of\nexisting cells, understand performance bottlenecks, and predict performance of\nperovskite-based solar panel - the obvious next step to the evolution of\nperovskite solar cell technology."
    },
    {
        "anchor": "Interference induced thermoelectric switching and heat rectification in\n  quantum Hall junctions: Interference represents one of the most striking manifestation of quantum\nphysics in low-dimensional systems. Despite evidences of quantum interference\nin charge transport have been known for a long time, only recently signatures\nof interference induced thermal properties have been reported, paving the way\nfor the phase-coherent manipulation of heat in mesoscopic devices. In this work\nwe show that anomalous thermoelectric properties and efficient heat\nrectification can be achieved by exploiting the phase-coherent edge states of\nquantum Hall systems. By considering a tunneling geometry with multiple quantum\npoint contacts, we demonstrate that the interference paths effectively break\nthe electron-hole symmetry, allowing for a thermoelectric charge current\nflowing either from hot to cold or viceversa, depending on the details of the\ntunnel junction. Correspondingly, an interference induced heat current is\npredicted, and we are able to explain these results in terms of an intuitive\nphysical picture. Moreover, we show that heat rectification can be achieved by\ncoupling two quantum Hall systems with different filling factors, and that this\neffect can be enhanced by exploiting the interference properties of the tunnel\njunction.",
        "positive": "Spin transport in ferromagnet-InSb nanowire quantum devices: Signatures of Majorana zero modes (MZMs), which are the building blocks for\nfault-tolerant topological quantum computing, have been observed in\nsemiconductor nanowires (NW) with strong spin-orbital-interaction (SOI), such\nas InSb and InAs NWs with proximity-induced superconductivity. Realizing\ntopological superconductivity and MZMs in this most widely-studied platform\nalso requires eliminating spin degeneracy, which is realized by applying a\nmagnetic field to induce a helical gap. However, the applied field can\nadversely impact the induced superconducting state in the NWs and also places\ngeometric restrictions on the device, which can affect scaling of future\nMZM-based quantum registers. These challenges could be circumvented by\nintegrating magnetic elements with the NWs. With this motivation, in this work\nwe report the first experimental investigation of spin transport across InSb\nNWs, which are enabled by devices with ferromagnetic (FM) contacts. We observe\nsignatures of spin polarization and spin-dependent transport in the\nquasi-one-dimensional ballistic regime. Moreover, we show that electrostatic\ngating tunes the observed magnetic signal and also reveals a transport regime\nwhere the device acts as a spin filter. These results open an avenue towards\ndeveloping MZM devices in which spin degeneracy is lifted locally, without the\nneed of an applied magnetic field. They also provide a path for realizing\nspin-based devices that leverage spin-orbital states in quantum wires."
    },
    {
        "anchor": "Edge states of zigzag bilayer graphite nanoribbons: Electronic structures of the zigzag bilayer graphite nanoribbons(Z-BGNR) with\nvarious ribbon width $N$ are studied within the tight binding approximation.\nNeglecting the inter-layer hopping amplitude $\\gamma_4$, which is an order of\nmagnitude smaller than the other inter-layer hopping parameters $\\gamma_1$ and\n$\\gamma_3$, there exist two fixed Fermi points $\\pm k^*$ independent of the\nribbon width with the peculiar energy dispersion near $k^*$ as $\\ve (k) \\sim\n\\pm (k-k^*)^N$. By investigating the edge states of the Z-BGNR, we notice that\nthe trigonal warping of the bilayer graphene sheets are reflected on in the\nedge state structure. With the inclusion of $\\gamma_4$, the above two Fermi\npoints are not fixed, but drift toward the vicinity of the Dirac point with the\nincrease of the width $N$ as shown by the finite scaling method and the\npeculiar dispersions change to the parabolic ones. The edge magnetism of the\nZ-BGNR is also examined by solving the half-filled Hubbard Hamiltonian for the\nribbon using the Hartree-Fock approximation. We have shown that within the same\nside of the edges, the edge spins are aligned ferromagnetically for the\nexperimentally relevant set of parameters.",
        "positive": "Antenna-enhanced Optoelectronic Probing of Carbon Nanotubes: We report on the first antenna-enhanced optoelectronic microscopy studies on\nnanoscale devices. By coupling the emission and excitation to a scanning\noptical antenna, we are able to locally enhance the electroluminescence and\nphotocurrent along a carbon nanotube device. We show that the emission source\nof the electroluminescence can be point-like with a spatial extension below 20\nnm. Topographic and antenna-enhanced photocurrent measurements reveal that the\nemission takes place at the location of highest local electric field indicating\nthat the mechanism behind the emission is the radiative decay of excitons\ncreated via impact excitation."
    },
    {
        "anchor": "A magnetically-induced Coulomb gap in graphene due to electron-electron\n  interactions: Insights into the fundamental properties of graphene's Dirac-Weyl fermions\nhave emerged from studies of electron tunnelling transistors in which an\natomically thin layer of hexagonal boron nitride (hBN) is sandwiched between\ntwo layers of high purity graphene. Here, we show that when a single defect is\npresent within the hBN tunnel barrier, it can inject electrons into the\ngraphene layers and its sharply defined energy level acts as a high resolution\nspectroscopic probe of electron-electron interactions in graphene. We report a\nmagnetic field dependent suppression of the tunnel current flowing through a\nsingle defect below temperatures of $\\sim$ 2 K. This is attributed to the\nformation of a magnetically-induced Coulomb gap in the spectral density of\nelectrons tunnelling into graphene due to electron-electron interactions.",
        "positive": "The influence of anisotropic Rashba spin-orbit coupling on\n  current-induced spin polarization in graphene: We consider a disordered graphene layer with anisotropic Rashba spin-orbit\ncoupling subjected to a longitudinal electric field. Using the linear response\ntheory we calculate current-induced spin polarization including in-plane normal\nand parallel components with respect to the electric field direction. Unlike\nthe case of isotropic Rashba spin-orbit where the normal component of spin\npolarization is linear in terms of Fermi energy around the Dirac point,\nanisotropic Rashba spin-orbit can result in non-linear dependence of this\ncomponent at such energies within the Lifshitz points. Furthermore, we show\nthat anisotropic Rashba interaction allows for tuning the direction of spin\npolarization from perpendicular direction to the parallel one such that for\ncertain values of Rashba parameters the magnitudes of both components can also\nbe quenched. The effect of carriers scattering on randomly distributed\nnon-magnetic disorders is also taken into account by calculating vertex\ncorrection. This results in modification of spin polarization components\ndepending on the relative strength of Rashba parameters."
    },
    {
        "anchor": "Spin-Hall Conductivity and Electric Polarization in Metallic Thin Films: We predict theoretically that, when a normal metallic thin film (without bulk\nspin-orbit coupling, such as Cu or Al) is sandwiched by two insulators, two\nprominent effects arise due to the interfacial spin-orbit coupling: a giant\nspin-Hall conductivity due to the surface scattering and a transverse electric\npolarization due to the spin-dependent phase shift in the spinor wave\nfunctions.",
        "positive": "Planar Josephson Junctions Templated by Nanowire Shadowing: More and more materials, with a growing variety of properties, are built into\nelectronic devices. This is motivated both by increased device performance and\nby the studies of materials themselves. An important type of device is a\nJosephson junction based on the proximity effect between a quantum material and\na superconductor, useful for fundamental research as well as for quantum and\nother technologies. When both junction contacts are placed on the same surface,\nsuch as a two-dimensional material, the junction is called ``planar\". One\noutstanding challenge is that not all materials are amenable to the standard\nplanar junction fabrication. The device quality, rather than the intrinsic\ncharacteristics, may be defining the results. Here, we introduce a technique in\nwhich nanowires are placed on the surface and act as a shadow mask for the\nsuperconductor. The advantages are that the smallest dimension is determined by\nthe nanowire diameter and does not require lithography, and that the junction\nis not exposed to chemicals such as etchants. We demonstrate this method with\nan InAs quantum well, using two superconductors - Al and Sn, and two\nsemiconductor nanowires - InAs and InSb. The junctions exhibit critical current\nlevels consistent with transparent interfaces and uniform width. We show that\nthe template nanowire can be operated as a self-aligned electrostatic gate.\nBeyond single junctions, we create SQUIDs with two gate-tunable junctions. We\nsuggest that our method can be used for a large variety of quantum materials\nincluding van der Waals layers, topological insulators, Weyl semimetals and\nfuture materials for which proximity effect devices is a promising research\navenue."
    },
    {
        "anchor": "Suppression of non-Poissonian shot noise by Coulomb correlations in\n  ballistic conductors: We investigate the current injection into a ballistic conductor under the\nspace-charge limited regime, when the distribution function of injected\ncarriers is an arbitrary function of energy F_c(epsilon). The analysis of the\ncoupled kinetic and Poisson equations shows that the injected current\nfluctuations may be essentially suppressed by Coulomb correlations, and the\nsuppression level is determined by the shape of F_c(epsilon). This is in\ncontrast to the time-averaged quantities: the mean current and the spatial\nprofiles are shown to be insensitive to F_c(epsilon) in the leading-order terms\nat high biases. The asymptotic high-bias behavior for the energy resolved\nshot-noise suppression has been found for an arbitrary (non-Poissonian)\ninjection, which may suggest a new field of investigation on the optimization\nof the injected energy profile to achieve the desired noise-suppression level.",
        "positive": "Strain-free GaSb quantum dots as single-photon sources in the telecom\n  S-band: Creating single photons in the telecommunication wavelength range from\nsemiconductor quantum dots (QDs) and interfacing them with spins of electrons\nor holes has been of high interest in recent years, with research mainly\nfocusing on indium based QDs. However, there is not much data on the optical\nand spin properties of galliumantimonide (GaSb) QDs, despite it being a\nphysically rich system with an indirect to direct bandgap crossover in the\ntelecom wavelength range. Here, we investigate the (quantum-) optical\nproperties of GaSb quantum dots, which are fabricated by filling droplet-etched\nnanoholes in an aluminum-galliumantimonide (AlGaSb) matrix. We observe\nphotoluminescence (PL) features from isolated and highly symmetric QDs that\nexhibit narrow linewidth in the telecom S-band and show an excitonic fine\nstructure splitting of $\\Delta E=(12.0\\pm0.5)\\mu eV$. Moreover, we perform\ntime-resolved measurements of the decay characteristics of an exciton and\nmeasure the second-order photon autocorrelation function of the charge complex\nto $g^{(2)}(0)=0.16\\pm0.02$, revealing clear antibunching and thus proving the\ncapability of this material platform to generate non-classical light."
    },
    {
        "anchor": "Strain distributions in lattice-mismatched semiconductor core-shell\n  nanowires: The authors study the elastic deformation field in lattice-mismatched\ncore-shell nanowires with single and multiple shells. The authors consider\ninfinite wires with a hexagonal cross section under the assumption of\ntranslational symmetry. The strain distributions are found by minimizing the\nelastic energy per unit cell using the finite element method. The authors find\nthat the trace of the strain is discontinuous with a simple, almost piecewise\nvariation between core and shell, whereas the individual components of the\nstrain can exhibit complex variations.",
        "positive": "Non-trivial effect of dephasing: Enhancement of rectification of spin\n  current in graded XX chains: In order to reveal mechanisms to control and manipulate spin currents, we\nperform a detailed investigation of the dephasing effects in the open XX model\nwith a Lindblad dynamics involving global dissipators and thermal baths.\nSpecifically, we consider dephasing noise modelled by current preserving\nLindblad dissipators acting on graded versions of these spin systems, that is,\nsystems in which the magnetic field and/or the spin interaction are growing\n(decreasing) along the chain. In our analysis, we study the non-equilibrium\nsteady-state via the covariance matrix using the Jordan-Wigner approach to\ncompute the spin currents. We find that the interplay between dephasing and\ngraded systems gives rise to a non trivial behavior: when we have homogeneous\nmagnetic field and graded interactions we have rectification enhancement\nmechanims, and when we have fully graded system we can control the spin current\nin order to keep the direction of the particle/spin flow even with inverted\nbaths. We describe our result in detailed numerical analisys and we see that\nrectification in this simple model indicates that the phenomenon may be of\ngeneral occurrence in quantum spin systems."
    },
    {
        "anchor": "First experimental evidence of one-dimensional plasma modes in\n  superconducting thin wires: We have studied niobium superconducting thin wires deposited onto a\nSrTiO$_{3}$ substrate. By measuring the reflection coefficient of the wires,\nresonances are observed in the superconducting state in the 130 MHz to 4 GHz\nrange. They are interpreted as standing wave resonances of one-dimensional\nplasma modes propagating along the superconducting wire. The experimental\ndispersion law, $\\omega$ versus $q$, presents a linear dependence over the\nentire wave vector range. The modes are softened as the temperature increases\nclose the superconducting transition temperature. Very good agreement are\nobserved between our data and the dispersion relation predicted by Kulik and\nMooij and Sch\\\"on.",
        "positive": "Improved Light Absorption by Quantum Confinement and Band Folding:\n  Enhanced Efficiency in Silicon Based Solar Cells: The improvement of light absorption in Si/BeSe$_{0.41}$Te$_{0.59}$\nheterostructures for solar cell applications is studied theoretically. First,\nusing simple approaches we found that light absorption could be improved in a\nsingle (uncoupled) quantum well with a thickness up to 20 {\\AA}. Second, by\nsemiempirical tight-binding methods we calculated the electronic structure and\noptical properties of various (Si$_{2})_{n}$/(BeSe$_{0.41}$Te$_{0.59})_{m}$\n[001] superlattices. Two bands of interface states were found in the band gap\nof bulk Si. Our calculations indicate that the optical edges are close to the\nfundamental band gap of bulk Si and the transitions are optically allowed."
    },
    {
        "anchor": "Acoustic wave tunneling across a vacuum gap between two piezoelectric\n  crystals with arbitrary symmetry and orientation: It is not widely appreciated that an acoustic wave can \"jump\" or \"tunnel\"\nacross a vacuum gap between two piezoelectric solids, nor has the general case\nbeen formulated or studied in detail. Here, we remedy that situation, by\npresenting a general formalism and approach to study such an acoustic tunneling\neffect between two arbitrarily oriented anisotropic piezoelectric semi-infinite\ncrystals. The approach allows one to solve for the reflection and transmission\ncoefficients of all the partial wave modes, and is amenable to practical\nnumerical or even analytical implementation, as we demonstrate by a few chosen\nexamples. The formalism can be used in the future for quantitative studies of\nthe tunneling effect in connection not only with the manipulation of acoustic\nwaves, but with many other areas of physics of vibrations such as heat\ntransport, for example.",
        "positive": "Distinct mechanisms of DNA sensing based on N-doped carbon nanotubes\n  with enhanced conductance and chemical selectivity: Carrying out first-principles calculations, we study N-doped capped carbon\nnanotube (CNT) electrodes applied to DNA sequencing. While we obtain for the\nface-on nucleobase junction configurations a conventional conductance ordering\nwhere the largest signal results from guanine according to its high highest\noccupied molecular orbital (HOMO) level, we extract for the edge-on\ncounterparts a distinct conductance ordering where the low-HOMO thymine\nprovides the largest signal. The edge-on mode is shown to operate based on a\nnovel molecular sensing mechanism that reflects the chemical connectivity\nbetween N-doped CNT caps that can act both as electron donors and electron\nacceptors and DNA functional groups that include the hyperconjugated thymine\nmethyl group."
    },
    {
        "anchor": "Statistics of Anderson-localized modes in disordered photonic crystal\n  slab waveguides: We present a fully three-dimensional Bloch mode expansion technique and\nphoton Green function formalism to compute the quality factor, mode volume, and\nPurcell enhancement distributions of a disordered W1 photonic crystal slab\nwaveguide in the slow-light Anderson localization regime. By considering\nfabrication (intrinsic) and intentional (extrinsic) disorder we find that the\nquality factor and Purcell enhancement statistics are well described by\nlog-normal distributions without any fitting parameters. We also compare\ndirectly the effects of hole size fluctuations as well as fluctuations in the\nhole position. The functional dependence of the mean and standard deviation of\nthe quality factor and Purcell enhancement distributions is found to decrease\nexponentially on the square root of the extrinsic disorder parameter. The\nstrong coupling probability between a single quantum dot and an\nAnderson-localized mode is numerically computed and found to exponential\ndecrease with the squared extrinsic disorder parameter, where low disordered\nsystems give rise to larger probabilities when state-of-art quantum dots are\nconsidered. The optimal regions to position quantum dots in the W1 waveguide\nare also discussed. These theoretical results are fundamental interesting and\nconnect to recent experimental works on photonic crystal slab waveguides in the\nslow-light regime.",
        "positive": "Semiconductor-to-Metal Transition in the Bulk of WSe2 upon Potassium\n  Intercalation: We present electron energy-loss spectroscopic measurements of potassium (K)\nintercalated tungsten diselenide (WSe2). After exposure of pristine WSe2 films\nto potassium, we observe a charge carrier plasmon excitation at about 0.97 eV,\nwhich indicates a semiconductor to metal transition. Our data signal the\nformation of one particular doped K-WSe2 phase. A Kramers-Kronig analysis (KKA)\nallows the determination of the dielectric function and to estimate the\ncomposition of about K0.6WSe2. Momentum dependent measurements reveal a\nsubstantial plasmon dispersion to higher energies."
    },
    {
        "anchor": "Quasi-ballistic heat conduction due to L\u00e9vy phonon flights in silicon\n  nanowires: Future of silicon-based microelectronics relies on solving the heat\ndissipation problem. A solution may lie in a nanoscale phenomenon known as\nballistic heat conduction, which implies heat conduction without heating the\nconductor. But, attempts to demonstrate this phenomenon experimentally are\ncontroversial and scarce whereas its mechanism in confined nanostructures is\nyet to be fully understood. Here, we experimentally demonstrate quasi-ballistic\nheat conduction in silicon nanowires (NWs). We show that the ballisticity is\nstrongest in short NWs at low temperatures but weakens as the NW length or\ntemperature is increased. Yet, even at room temperature, quasi-ballistic heat\nconduction remains visible in short NWs. To better understand this phenomenon,\nwe probe directionality and lengths of phonon flights. Our experiments and\nsimulations show that the quasi-ballistic phonon transport in NWs is the L\\'evy\nwalk with short flights between the NW boundaries and long ballistic leaps\nalong the NW.",
        "positive": "Spin and valley transports in junctions of Dirac fermions: We study spin and valley transports in junctions composed of silicene and\ntopological crystalline insulators. We consider normal/magnetic/normal Dirac\nmetal junctions where a gate electrode is attached to the magnetic region. In\nnormal/antiferromagnetic/normal silicene junction, we show that the current\nthrough this junction is valley and spin polarized due to the coupling between\nvalley and spin degrees of freedom, and the valley and spin polarizations can\nbe tuned by local application of a gate voltage. In particular, we find a fully\nvalley and spin polarized current by applying the electric field. In\nnormal/ferromagnetic/normal topological crystalline insulator junction with a\nstrain induced in the ferromagnetic segment, we investigate valley resolved\nconductances and clarify how the valley polarization stemming from the strain\nand exchange field appears in this junction. It is found that changing the\ndirection of the magnetization and the potential in the ferromagnetic region,\none can control the dominant valley contribution out of four valley degrees of\nfreedom. We also review spin transport in normal/ferromagnetic/normal graphene\njunctions, and spin and valley transports in normal/ferromagnetic/normal\nsilicene junctions for comparison."
    },
    {
        "anchor": "Efficient spin injection into graphene through trilayer hBN tunnel\n  barriers: We characterize the spin injection into bilayer graphene fully encapsulated\nin hBN using trilayer (3L) hexagonal boron nitride (hBN) tunnel barriers. As a\nfunction of the DC bias, the differential spin injection polarization is found\nto rise up to -60% at -250 mV DC bias voltage. We measure a DC spin\npolarization of $\\sim$ 50%, a 30% increase compared to 2L-hBN. The large\npolarization is confirmed by local, two terminal spin transport measurements up\nto room temperature. We observe comparable differential spin injection\nefficiencies from Co/2L-hBN and Co/3L-hBN into graphene and conclude that\npossible exchange interaction between cobalt and graphene is likely not the\norigin of the bias dependence. Furthermore, our results show that local gating,\narising from the applied DC bias is not responsible for the DC bias dependence.\nCarrier density dependent measurements of the spin injection efficiency are\ndiscussed, where we find no significant modulation of the differential spin\ninjection polarization. We also address the bias dependence of the injection of\nin-plane and out-of-plane spins and conclude that the spin injection\npolarization is isotropic and does not depend on the applied bias.",
        "positive": "Hinge mode dynamics of periodically driven higher-order Weyl semimetals: We study the stroboscopic dynamics of hinge modes of a second-order\ntopological material modeled by a tight-binding free fermion Hamiltonian on a\ncubic lattice in the intermediate drive frequency regime for both discrete\n(square pulse) and continuous (cosine) periodic drive protocols. We analyze the\nFloquet phases of this system and show that its quasienergy spectrum becomes\nalmost gapless in the large drive amplitude regime at special drive\nfrequencies. Away from these frequencies, the gapped quasienergy spectrum\nsupports weakly dispersing Floquet hinge modes. Near them, these hinge modes\npenetrate into the bulk and eventually become indistinguishable from the bulk\nmodes. We provide an analytic, albeit perturbative, expression for the Floquet\nHamiltonian using Floquet perturbation theory (FPT) which explains this\nphenomenon and leads to analytic expressions of these special frequencies. We\nalso show that in the large drive amplitude regime, the zero energy hinge modes\ncorresponding to the static tight-binding Hamiltonian display qualitatively\ndifferent dynamics at these special frequencies. We discuss possible local\ndensity of state measurement using a scanning tunneling microscope which can\ntest our theory."
    },
    {
        "anchor": "Shock Waves in Nanomechanical Resonators: The dream of every surfer is an extremely steep wave propagating at the\nhighest speed possible. The best waves for this would be shock waves, but are\nvery hard to surf. In the nanoscopic world the same is true: the surfers in\nthis case are electrons riding through nanomechanical devices on acoustic waves\n[1]. Naturally, this has a broad range of applications in sensor technology and\nfor communication electronics for which the combination of an electronic and a\nmechanical degree of freedom is essential. But this is also of interest for\nfundamental aspects of nano-electromechanical systems (NEMS), when it comes to\nquantum limited displacement detection [2] and the control of phonon number\nstates [3]. Here, we study the formation of shock waves in a NEMS resonator\nwith an embedded two-dimensional electron gas using surface acoustic waves. The\nmechanical displacement of the nano-resonator is read out via the induced\nacoustoelectric current. Applying acoustical standing waves we are able to\ndetermine the anomalous acoustocurrent. This current is only found in the\nregime of shock wave formation. We ontain very good agreement with model\ncalculations.",
        "positive": "Layer Coherent Phase in Double Layer graphene at $\u03bd^{}_1=\u03bd^{}_2=0$: In the recent advancement in graphene heterostructures, it is possible to\ncreate a double layer tunnel decoupled graphene system that has a strong\ninterlayer electronic interaction. In this work, we restrict the parameters in\nthe low energy effective Hamiltonian using simple symmetry arguments. Then, we\nstudy the ground state of this system in the Hartree-Fock approximation at\n$\\nu^{}_1=\\nu^{}_2=0$. In addition to the phases found in monolayer graphene,\nwe found an existence of layer coherent phase which breaks the layer $U(1)$\nsymmetry. At non-zero Zeeman coupling strength ($E^{}_z$), this layer coherent\nstate has a small magnetization, that vanishes when $E^{}_z$ tends to zero. We\ndiscuss the bulk gapless modes using the Goldstone theorem. We also comment on\nthe edge structure for the layer coherent phase."
    },
    {
        "anchor": "A nanogapped hysteresis-free field-effect transistor: We propose a semi-suspended device structure and construct nanogapped,\nhysteresis-free field-effect transistors (FETs), based on the van der Waals\nstacking technique. The structure, which features a semi-suspended channel\nabove a submicron-long wedge-like nanogap, is fulfilled by transferring\nultraclean BN-supported MoS$_2$ channels directly onto dielectric-spaced\nvertical source/drain stacks. Electronic characterization and analyses reveal a\nhigh overall device quality, including ultraclean channel interfaces,\nnegligible electrical scanning hysteresis, and Ohmic contacts in the\nstructures. The unique hollow FET structure holds the potential for exploiting\nreliable electronics, as well as nanofluid and pressure sensors.",
        "positive": "Tunable coupling of terahertz Dirac plasmons and phonons in transition\n  metal dicalchogenide-based van der Waals heterostructures: Dirac plasmons in graphene hybridize with phonons of transition metal\ndichalcogenides (TMDs) when the materials are combined in so-called van der\nWaals heterostructures (vdWh), thus forming surface plasmon-phonon polaritons\n(SPPPs). The extend to which these modes are coupled depends on the TMD\ncomposition and structure, but also on the plasmons' properties. By performing\nrealistic simulations that account for the contribution of each layer of the\nvdWh separately, we calculate how the strength of plasmon-phonon coupling\ndepends on the number and composition of TMD layers, on the graphene Fermi\nenergy and the specific phonon mode. From this, we present a semiclassical\ntheory that is capable of capturing all relevant characteristics of the SPPPs.\nWe find that it is possible to realize both strong and ultra-strong coupling\nregimes by tuning graphene's Fermi energy and changing TMD layer number."
    },
    {
        "anchor": "Observation of spin-glass behavior in nickel adsorbed few layer graphene: Nickel-adsorbed graphene was prepared by first synthesizing graphite oxide\n(GO) by modified Hummers' method and then reducing a solution containing both\nGO and $Ni^{2+}$. EDX analysis showed 31 atomic percent nickel was present.\nMagnetization measurements under both dc and ac magnetic fields were carried\nout in the temperature range 2 K to 300 K. The zero field cooled and field\ncooled magnetization data showed a pronounced irreversibility at a temperature\naround 20 K. The analysis of the ac susceptibility data were carried out by\nboth Vogel-Fulcher as well as power law. From dynamic scaling analysis the\nmicroscopic flipping time $\\tau_{0}\\sim 10^{-13} s$ and critical exponent\n$z\\nu=5.9\\pm0.1$ were found, indicating presence of conventional spin glass in\nthe system. The spin glass transition temperature was estimated as 19.5 K.\n  Decay of thermoremanent magnetization (TRM) was explained by stretched\nexponential function with a value of the exponent as 0.6 .\n  From the results it is concluded that nickel adsorbed graphene behaves like a\nspin-glass.",
        "positive": "Topological changes of two-dimensional magnetic textures: We investigate the interaction of magnetic vortices and skyrmions with a\nspin-polarized current. In a square lattice, fixed classical spins and quantum\nitinerant electrons, evolve according to the coupled Landau-Lifshitz and\nSchr\\\"odinger equations. Changes in the topology occur at microscopic time and\nlength scales, and are shown to be triggered by the nucleation of a nontrivial\nelectron-spin structure at the vortex core."
    },
    {
        "anchor": "Subband Engineering Even-Denominator Quantum Hall States: Proposed even-denominator fractional quantum Hall effect (FQHE) states\nsuggest the possibility of excitations with non-Abelian braid statistics.\nRecent experiments on wide square quantum wells observe even-denominator FQHE\neven under electrostatic tilt. We theoretically analyze these structures and\ndevelop a procedure to accurately test proposed quantum Hall wavefunctions. We\nfind that tilted wells favor partial subband polarization to yield Abelian\neven-denominator states. Our results show that tilting quantum wells\neffectively engineers different interaction potentials allowing exploration of\na wide variety of even-denominator states.",
        "positive": "Interference of coherent spin waves in micron-sized ferromagnetic\n  waveguides: We present experimental observations of the interference of spin-wave modes\npropagating in opposite directions in micron-sized NiFe-waveguides. To monitor\nthe local spin-wave intensity distribution and phase of the formed interference\npattern, we use Brillouin light scattering microscopy. The two-dimensional\nspin-wave intensity map can be understood by considering the interference of\nseveral waveguide eigenmodes with different wavevectors quantized across the\nwidth of the stripe. The phase shows a transition from linear dependence on the\nspace coordinate near the antennas characteristic for propagating waves to\ndiscrete values in the center region characteristic for standing waves."
    },
    {
        "anchor": "Dynamical Properties in the Bilayer Quantum Hall Ferromagnet: The spectral functions of the pseudospin correlation functions in the bilayer\nquantum Hall system at \\nu=1 are investigated numerically, where the pseudospin\ndescribes the layer degrees of freedom. In the pseudospin-ferromagnetic phase,\nthe lowest-energy excitation branch is closely connected with the ground state\nthrough the fluctuations of pseudospin S_y and S_z, and it plays a significant\nrole on the tunneling properties in this system. For the system with very small\ntunneling amplitude and layer separation smaller than the critical one, the\nsystem-size dependence of calculated spectral function A_{y z} suggests the\nsuperfluidity on the tunneling current in the absence of impurities.",
        "positive": "Spin-polarization of platinum (111) induced by the proximity to cobalt\n  nanostripes: We measured a spin polarization above a Pt (111) surface in the vicinity of a\nCo nanostripe by spin-polarized scanning tunneling spectroscopy. The spin\npolarization is exponentially decaying away from the Pt/Co interface and is\ndetectable at distances larger than 1 nm. By performing self-consistent\nab-initio calculations of the electronic-structure for a related model system\nwe reveal the interplay between the induced magnetic moments within the Pt\nsurface and the spin-resolved electronic density of states above the surface."
    },
    {
        "anchor": "Confluence of resonant laser excitation and bi-directional quantum dot\n  nuclear spin polarization: Resonant laser scattering along with photon correlation measurements have\nestablished the atom-like character of quantum dots. Here, we present\nmeasurements which challenge this identification for a wide range of\nexperimental parameters: the absorption lineshapes that we measure at magnetic\nfields exceeding 1 Tesla indicate that the nuclear spins polarize by an amount\nthat ensures locking of the quantum dot resonances to the incident laser\nfrequency. In contrast to earlier experiments, this nuclear spin polarization\nis bi-directional, allowing the electron+nuclear spin system to track the\nchanges in laser frequency dynamically on both sides of the quantum dot\nresonance. Our measurements reveal that the confluence of the laser excitation\nand nuclear spin polarization suppresses the fluctuations in the resonant\nabsorption signal. A master equation analysis shows narrowing of the nuclear\nOverhauser field variance, pointing to potential applications in quantum\ninformation processing.",
        "positive": "Long-range-correlated disorder in graphene: We study transport of two-dimensional quasi-relativistic electronic\nexcitations in graphene in the presence of static long-range-correlated random\nscalar and vector potentials. Using a combination of perturbation theory and\npath-integral techniques, we estimate scattering rates which control Drude\nconductivity, magneto-transport, and Friedel oscillations in the ballistic\nregime of large quasiparticle energies. We also discuss properties of\nzero-energy states and pertinent localization scenarios."
    },
    {
        "anchor": "Numerical study of Klein quantum dots in graphene system: Klein quantum dot (KQD) refers to a QD with quasi-bound states and a finite\ntrapping time, which has been observed in experiments focused on graphene\nrecently. In this paper, we develop a numerical method to calculate local\ndensity of states (LDOS) of KQD and apply it to monolayer graphene. By\ninvestigating the variation of LDOS in a circular quantum dot, we obtain the\ndependence of the quasi-bound states on the quantum dot parameters (e.g. the\nelectron energy, radius, confined potential, etc). Based on these results, not\nonly can we well explain the experimental phenomena, but also demonstrate how\nquasi-bound states turn to real bound states when intervalley scattering is\ntaken into considered. We further study the evolution of the LDOS for KQD\nvarying from a circle shape to a semicircle shape, which reveals the mechanism\nof whispering gallery mode on the quasi-bound states.",
        "positive": "Limited accuracy of conduction band effective mass equations for\n  semiconductor quantum dots: Effective mass equations are the simplest models of carrier states in a\nsemiconductor structures that reduce the complexity of a solid-state system to\nSchr\\\"odinger- or Pauli-like equations resempling those well known from quantum\nmechanics textbooks. Here we present a systematic derivation of a\nconduction-band effective mass equation for a self-assembled semiconductor\nquantum dot in a magnetic field from the 8-band kp theory. The derivation\nallows us to classify various forms of the effective mass equations in terms of\na hierarchy of approximations. We assess the accuracy of the approximations in\ncalculating selected spectral and spin-related characteristics. We indicate the\nimportance of preserving the off-diagonal terms of the valence band Hamiltonian\nand argue that an effective mass theory cannot reach satisfactory accuracy\nwithout self-consistently including non-parabolicity corrections and\nrenormalization of kp parameters. Quantitative comparison with the 8-band kp\nresults supports the phenomenological Roth-Lax-Zwerdling formula for the\ng-factor in a nanostructure."
    },
    {
        "anchor": "A Better Method for Volume Determination of Regularly and Irregularly\n  Shaped Nanoparticles with Enhanced Accuracy: Nanoparticles (NPs) are widely used in diverse application areas, such as\nmedicine, engineering, and cosmetics. The size (or volume) of NPs is one of the\nmost important parameters for their successful application. It is relatively\nstraightforward to determine the volume of regular NPs such as spheres and\ncubes from a one-dimensional or two-dimensional measurement. However, due to\nthe three-dimensional nature of NPs, it is challenging to determine the proper\nphysical size of many types of regularly and irregularly-shaped NPs (IS-NPs) at\nhigh-throughput using a single tool. Here, we present a relatively simple\nmethod that statistically determines a better volume estimate of many types of\nNPs by combining measurements from their top-down projection areas and\npeak-heights using two tools. The proposed method is significantly faster and\nmore economical than the electron tomography method. We demonstrate the\nimproved accuracy of the combined method over scanning electron microscopy\n(SEM) and atomic force microscopy (AFM) by using both modeling and\nmeasurements. This study also shows that SEM provides a more accurate estimate\nof size than AFM for most IS-NP size measurements. The method provides a much\nneeded, proper high-throughput volumetric measurement method useful for many\napplications.",
        "positive": "Pseudosymmetric bias and correct estimation of Coulomb/confinement\n  energy for unintentional quantum dot in channel of metal-oxide-semiconductor\n  field-effect transistor: We describe a measurement method that enables the correct estimation of the\ncharging energy of an unintentional quantum dot (QD) in the channel of a\nmetal-oxide-semiconductor field-effect transistor (MOSFET). If the channel has\na dominant QD with a large charging energy and an array of stray QDs with much\nweaker charging, this method eliminates the additional voltage drops due to\nstray QDs by regarding the stray QDs as series resistors. We apply this method\nto a short-channel MOSFET and find that the charging energy of the dominant QD\ncan indeed be smaller than the size of the Coulomb diamond."
    },
    {
        "anchor": "Fermi liquid parameters in 2D with spin-orbit interaction: We derive analytical expressions for the quasiparticle lifetime tau, the\neffective mass m*, and the Green's function renormalization factor Z for a 2D\nFermi liquid with electron-electron interaction in the presence of the Rashba\nspin-orbit interaction. We find that the modifications are independent of the\nRashba band index rho, and occur in second order of the spin-orbit coupling\nalpha. In the derivation of these results, we also discuss the screening of the\nCoulomb interaction, as well as the susceptibility and the self-energy in small\nalpha.",
        "positive": "Measurement of Topological Order based on Metric-Curvature\n  Correspondence: A unified expression for topological invariants has been proposed recently to\ndescribe the topological order in Dirac models belonging to any dimension and\nsymmetry class. We uncover a correspondence between the curvature function that\nintegrates to this unified topological invariant and the quantum metric that\nmeasures the distance between properly defined many-body Bloch states in\nmomentum space. Based on this metric-curvature correspondence, a time-resolved\nand angle-resolved photoemission spectroscopy experiment is proposed to measure\nthe violation of spectral sum rule caused by a pulse electric field to detect\nthe quantum metric, from which the topological properties of the system may be\nextracted."
    },
    {
        "anchor": "Enhanced excitation of a driven bistable system induced by spectrum\n  degeneracy: The non-equilibrium statistics and kinetics of a simple bistable system\n(resonantly driven nonlinear oscillator coupled to reservoir) have been\ninvestigated by means of master equation for the density matrix and\nquasiclassical Fokker-Planck equation in quasienergy space. We found out that\nthe system's statistical and kinetic properties drastically change when the\nquasienergy states become nearly degenerate and the occupation of the most\nexcited state is strongly enhanced. It has been revealed that in nearly\ndegenerate case a new critical quasienergy parameter emerges. Below the\ncritical quasienergy value the eigenstates are superpositions of the\nquasiclassical states from different phase space regions, while above this\nvalue the eigenstates correspond to only one particular region of the phase\nspace. We have also generalized Keldysh theory for ionization of atoms in the\nelectromagnetic field for bistable systems. It has been demonstrated that\nKeldysh parameter in bistability region is large when pumping intensity is\nsmaller than the critical value. It has been shown by direct calculations that\nmulti-photon transition amplitude coincides with the tunneling amplitude. So,\nmulti-photon transitions and tunneling between the regions of the phase space\nare just the same effects. We also demonstrated that for bistable systems the\nKeldysh parameter logarithmically depends on the external field amplitude.",
        "positive": "Spin relaxation and decoherence of two-level systems: We revisit the concepts of spin relaxation and spin decoherence of two level\n(spin-1/2) systems. From two toy-models, we clarify two issues related to the\nspin relaxation and decoherence: 1) For an ensemble of two-level particles each\nsubjected to a different environmental field, there exists an ensemble\nrelaxation time $T_1^*$ which is fundamentally different from $T_1$. When the\noff-diagonal coupling of each particle is in a single mode with the same\nfrequency but a random coupling strength, we show that $T_1^*$ is finite while\nthe spin relaxation time of a single spin $T_1$ and the usual ensemble\ndecoherence time $T_2^*$ are infinite. 2) For a two-level particle under only a\nrandom diagonal coupling, its relaxation time $T_1$ shall be infinite but its\ndecoherence time $T_2$ is finite."
    },
    {
        "anchor": "Higher-order ferromagnetic resonances in periodic arrays of\n  synthetic-antiferromagnet nanodiscs: We investigate spin dynamics in nanodisc arrays of synthetic-antiferromagnets\n(SAF) made of Py/NiCu/Py trilayers, where the NiCu spacer undergoes a Curie\ntransition at about 200 K. The observed ferromagnetic resonance spectra have\nthree distinct resonance modes at room temperature, which are fully recreated\nin our micromagnetic simulations showing also how the intra-SAF asymmetry can\nbe used to create and control the higher-order resonances in the structure.\nBelow the Curie temperature of the spacer, the system effectively transitions\ninto a single-layer nanodisc array with only two resonance modes. Our results\nshow how multi-layering of nano-arrays can add tunable GHz functionality\nrelevant for such rapidly developing fields as magnetic meta-materials,\nmagnonic crystals, arrays of spin-torque oscillators and neuromorphic\njunctions.",
        "positive": "Disorder by order in graphene: We predict the existence of an intriguing \"disorder by order\" phenomenon in\ngraphene transport where higher quality (and thus more ordered) samples, while\nhaving higher mobility at high carrier density, will manifest more strongly\ninsulating (and thus effectively more disordered) behavior as the carrier\ndensity is lowered compared with lower quality samples (with higher disorder)\nwhich exhibit an approximate resistivity saturation phenomenon at low carrier\ndensity near the Dirac point. This predicted behavior simulating a\nmetal-insulator transition, which we believe to have recently been observed in\nan experiment at Manchester University [L. A. Ponomarenko et al., Nat. Phys. 7,\n958 (2011)], arises from the suppression of Coulomb disorder induced\ninhomogeneous puddles near the charge neutrality point in high quality graphene\nsamples."
    },
    {
        "anchor": "Lattice rotation vortex at the monoclinic ferroelectric domain boundary\n  in relaxor ferroelectric crystal: We present the evidence of lattice rotation vortices having an average radius\nof ~7 nm at the monoclinic ferroelectric domain boundary of\n(1-x)Pb(Zn1/3Nb2/3)O3-xPbTiO3 (PZN-xPT, x=0.08). Maps of crystal orientations,\ndomain configurations, symmetry breaking are obtained using scanning convergent\nbeam electron diffraction (SCBED). Such measurements suggest the merging of 2D\nand 1D topological defects, with implications for domain-switching mechanisms\nin relaxor ferroelectric crystals, and the possibility of a new form of\nnanoscale ferroelectric devices.",
        "positive": "Spatial magnetization profile in spherical nanomagnets with surface\n  anisotropy: Green's function approach: We consider a single spherical nanomagnet and investigate the spatial\nmagnetization profile $\\mathbf{m}\\left(\\mathbf{r}\\right)$ in the continuum\napproach, using the Green's function formalism. The energy of the (many-spin)\nnanomagnet comprises an isotropic exchange interaction, a uniaxial anisotropy\nin the core and N\\'eel's surface anisotropy, and an external magnetic field. We\nderive a semi-analytical expression for the magnetization vector field\n$\\mathbf{m}\\left(\\mathbf{r}\\right)$ for an arbitrary position $\\mathbf{r}$\nwithin and on the boundary of the nanomagnet, as a solution of a homogeneous\nHelmholtz equation with inhomogeneous Neumann boundary conditions.\n  ...\n  For a more plausible comparison with experiments, e.g. using the technique of\nsmall-angle magnetic neutron scattering, we have averaged over the direction\nsolid angle and derived the spatial profile in terms of the distance $r$. We\nbelieve that the predictions of the present study could help to characterize\nand understand the effects of size and surface anisotropy on the magnetization\nconfigurations in nanomagnet assemblies such as arrays of well-spaced\nplatelets."
    },
    {
        "anchor": "Gated Spin Transport through an Individual Single Wall Carbon Nanotube: Hysteretic switching in the magnetoresistance of short-channel,\nferromagnetically contacted individual single wall carbon nanotubes is\nobserved, providing strong evidence for nanotube spin transport. By varying the\nvoltage on a capacitively coupled gate, the magnetoresistance can be\nreproducibly modified between +10% and -15%. The results are explained in terms\nof wave vector matching of the spin polarized electron states at the\nferromagnetic / nanotube interfaces.",
        "positive": "Acoustic Higher-Order Topological Insulators Protected by Multipole\n  Chiral Numbers: Recently, the higher-order topological phases from the chiral AIII symmetry\nclasses are characterized by a Z topological invariant known as the multipole\nchiral numbers, which indicate the number of degenerate zero-energy corner\nstates at each corner. Here, we report the first experimental realization of\nhigher-order topological insulators protected by multipole chiral numbers with\nusing acoustic crystals. Our acoustic measurements demonstrate unambiguously\nthe emergence of multiple corner states in the middle of the gap, as predicted\nby the quantized multipole chiral numbers. Our study may provoke new\npossibilities for controlling sound, such as acoustic sensing and energy\ntrapping."
    },
    {
        "anchor": "Raman fingerprints of atomically precise graphene nanoribbons: Bottom-up approaches allow the production of ultra-narrow and atomically\nprecise graphene nanoribbons (GNRs), with electronic and optical properties\ncontrolled by the specific atomic structure. Combining Raman spectroscopy and\nab-initio simulations, we show that GNR width, edge geometry and functional\ngroups all influence their Raman spectra. The low-energy spectral region below\n1000 cm-1 is particularly sensitive to edge morphology and functionalization,\nwhile the D peak dispersion can be used to uniquely fingerprint the presence of\nGNRs, and differentiates them from other sp2 carbon nanostructures.",
        "positive": "Lifshitz transition and van Hove singularity in a Topological Dirac\n  Semimetal: A topological Dirac semimetal is a novel state of quantum matter which has\nrecently attracted much attention as an apparent 3D version of graphene. In\nthis paper, we report critically important results on the electronic structure\nof the 3D Dirac semimetal Na3Bi at a surface that reveals its nontrivial\ngroundstate. Our studies, for the first time, reveal that the two 3D Dirac\ncones go through a topological change in the constant energy contour as a\nfunction of the binding energy, featuring a Lifshitz point, which is missing in\na strict 3D analog of graphene (in other words Na3Bi is not a true 3D analog of\ngraphene). Our results identify the first example of a band saddle point\nsingularity in 3D Dirac materials. This is in contrast to its 2D analogs such\nas graphene and the helical Dirac surface states of a topological insulator.\nThe observation of multiple Dirac nodes in Na3Bi connecting via a Lifshitz\npoint along its crystalline rotational axis away from the Kramers point serves\nas a decisive signature for the symmetry-protected nature of the Dirac\nsemimetal's topological groundstate."
    },
    {
        "anchor": "Material-Dependencies of the THz Emission from Plasmonic Graphene-Based\n  Photoconductive Antenna Structures: Graphene supports surface plasmon polaritons with comparatively slow\npropagation velocities in the THz region, which becomes increasingly\ninteresting for future communication technologies. This ability can be used to\nrealize compact antennas, which are up to two orders of magnitude smaller than\ntheir metallic counterparts. For a proper functionality of these antennas some\nminimum material requirements have to be fulfilled, which are presently\ndifficult to achieve, since the fabrication and transfer technologies for\ngraphene are still evolving. In this work we analyze available graphene\nmaterials experimentally and extract intrinsic characteristics at THz\nfrequencies, in order to predict the dependency of the THz signal emission\nthreshold as a function of the graphene relaxation time tau_r and the chemical\npotential mu_c.",
        "positive": "Topologically Protected Extended States in Disordered Quantum Spin-Hall\n  Systems without Time-Reversal Symmetry: We demonstrate the existence of robust bulk extended states in the disordered\nKane-Mele model with vertical and horizontal Zeeman fields, in the presence of\na large Rashba coupling. The phase diagrams are mapped out by using level\nstatistics analysis and computations of the localization length and spin-Chern\nnumbers $C_\\pm$. $C_\\pm$ are protected by the finite energy and spin mobility\ngaps. The latter is shown to stay open for arbitrarily large vertical Zeeman\nfields, or for horizontal Zeeman fields below a critical strength or at\nmoderate disorder. In such cases, a change of $C_\\pm$ is necessarily\naccompanied by the closing of the mobility gap at the Fermi level. The\nnumerical simulations reveal sharp changes in the quantized values of $C_\\pm$\nwhen crossing the regions of bulk extended states, indicating that the\ntopological nature of the extended states is indeed linked to the spin-Chern\nnumbers. For large horizontal Zeeman fields, the spin-gap closes at strong\ndisorder prompting a change in the quantized spin-Chern numbers without a\nclosing of the energy mobility gap."
    },
    {
        "anchor": "Anisotropic complex refractive indices of atomically thin materials:\n  determination of the optical constants of few-layer black phosphorus: In this work we briefly review the studies of the optical constants of\nmonolayer transition metal dichalcogenides and few layer black phosphorus, with\nparticular emphasis to the complex dielectric function and refractive index.\nSpecifically, we give an estimate of the complex index of refraction of\nphosphorene and few-layer black phosphorus. We extracted the complex index of\nrefraction of this material from differential reflectance data reported in\nliterature by employing a constrained Kramers-Kronig analysis. Finally, we\nstudied the linear optical response of multilayer systems embedding phosphorene\nby using the transfer matrix method.",
        "positive": "Effects of biased and unbiased illuminations on dopant-free GaAs/AlGaAs\n  2DEGs: Illumination is performed at low temperature on dopant-free two-dimensional\nelectron gases (2DEGs) of varying depths, under unbiased (gates grounded) and\nbiased (gates at a positive or negative voltage) conditions. Unbiased\nilluminations in 2DEGs located more than 70 nm away from the surface result in\na gain in mobility at a given electron density, primarily driven by the\nreduction of background impurities. In 2DEGs closer to the surface, unbiased\nilluminations result in a mobility loss, driven by an increase in surface\ncharge density. Biased illuminations performed with positive applied gate\nvoltages result in a mobility gain, whereas those performed with negative\napplied voltages result in a mobility loss. The magnitude of the mobility gain\n(loss) weakens with 2DEG depth, and is likely driven by a reduction (increase)\nin surface charge density. Remarkably, this mobility gain/loss is fully\nreversible by performing another biased illumination with the appropriate gate\nvoltage, provided both n-type and p-type ohmic contacts are present.\nExperimental results are modeled with Boltzmann transport theory, and possible\nmechanisms are discussed."
    },
    {
        "anchor": "Geometric effects on the electronic structure of curved nanotubes and\n  curved graphene: the case of the helix, catenary, helicoid, and catenoid: Since electrons in a ballistic regime perceive a carbon nanotube or a\ngraphene layer structure as a continuous medium, we can use the study of the\nquantum dynamics of one electron constrained to a curve or surface to obtain a\nqualitative description of the conduction electrons' behavior. The confinement\nprocess of a quantum particle to a curve or surface leads us, in the so-called\n\"confining potential formalism\" (CPF), to a geometry-induced potential (GIP) in\nthe effective Schr\\\"odinger equation. With these considerations, this work aims\nto study in detail the consequences of constraining a quantum particle to a\nhelix, catenary, helicoid, or catenoid, exploring the relations between these\ncurves and surfaces using differential geometry. Initially, we use the\nvariational method to estimate the energy of the particle in its ground state,\nand thus, we obtain better approximations with the use of the confluent Heun\nfunction through numerical calculations. Thus, we conclude that a quantum\nparticle constrained to an infinite helix has its angular momentum quantized\ndue to the geometry of the curve, while in the cases of the catenary, helicoid,\nand catenoid the particle can be found either in a single bound state or in\nexcited states which constitute a continuous energy band. Additionally, we\npropose measurements of physical observables capable of discriminating the\ntopologies of the studied surfaces, in the context of topological metrology.",
        "positive": "Spin edge helices in a perpendicular magnetic field: We present an exact solution to the problem of the spin edge states in the\npresence of equal Bychkov-Rashba and Dresselhaus spin-orbit fields in a\ntwo-dimensional electron system, restricted by a hard-wall confining potential\nand exposed to a perpendicular magnetic field. We find that the spectrum of the\nspin edge states depends critically on the orientation of the sample edges with\nrespect to the crystallographic axes. Such a strikingly different spectral\nbehavior generates new modes of the persistent spin helix-spin edge helices\nwith novel properties, which can be tuned by the applied electric and magnetic\nfields."
    },
    {
        "anchor": "Efficient method to calculate energy spectra for analysing\n  magneto-oscillations: Magneto-oscillations in two-dimensional systems with spin-orbit interaction\nare typically characterized by fast Shubnikov-de~Haas (SdH) oscillations and\nslower spin-orbit-related beatings. The characterization of the full SdH\noscillatory behavior in systems with both spin-orbit interaction and Zeeman\ncoupling requires a time consuming diagonalization of large matrices for many\nmagnetic field values. By using the Poisson summation formula we can explicitly\nseparate the density of states into, fast and slow oscillations, which\ndetermine the corresponding fast and slow parts of the magneto-oscillations. We\nintroduce an efficient scheme of partial diagonalization of our Hamiltonian,\nwhere only states close to the Fermi energy are needed to obtain the SdH\noscillations, thus reducing the required computational time. This allows an\nefficient method for fitting numerically the SdH data, using the inherent\nseparation of the fast and slow oscillations. We compare systems with only\nRashba spin-orbit interaction (SOI) and both Rashba and Dresselhaus SOI with,\nand without, an in-plane magnetic field. The energy spectra are characterized\nin terms of symmetries, which have direct and visible consequences in the\nmagneto-oscillations. To highlight the benefits of our methodology, we use it\nto extract the spin-orbit parameters by fitting realistic transport data.",
        "positive": "Room-Temperature Bound States in the Continuum Polariton Condensation: Exciton-polaritons resulting from the strong exciton-photon interaction\nstimulate the development of novel coherent light sources with low threshold,\nlong range spatial, and temporal coherence to circumvent the ever increasing\nenergy demands of optical communications. Polaritons from bound states in the\ncontinuum (BICs) are promising for Bose-Einstein condensation owing to their\ninfinite quality factors that enlarge photon lifetimes and benefit polariton\naccumulations. However, BIC polariton condensation remains limited to cryogenic\ntemperatures ascribed to the small exciton binding energies of conventional\nmaterial platforms. Herein, we demonstrated a room-temperature BIC polaritonic\nplatform based on halide perovskite air-hole photonic crystals, profiting from\nthe non-radiative BIC states and stable excitons of cesium lead bromide. BIC\npolariton condensation was achieved near the dispersion minimum that generates\ndirectional vortex beam emission with long-range coherence. Our work provides a\nsignificant basis for the applications of polariton condensates for integrated\nphotonic and topological circuits."
    },
    {
        "anchor": "Spin and reoccupation noise in a single quantum dot beyond the\n  fluctuation-dissipation theorem: We report on the nonequilibrium spin noise of a single InGaAs quantum dot\ncharged by a single hole under strong driving by a linearly polarized probe\nlight field. The spectral dependency of the spin noise power evidences a\nhomogeneous broadening and negligible charge fluctuations in the environment of\nthe unbiased quantum dot. Full analysis of the spin noise spectra beyond the\nfluctuation-dissipation theorem yields the heavy-hole spin dynamics as well as\nthe trion spin dynamics. Moreover, the experiment reveals an additional much\nweaker noise contribution in the Kerr rotation noise spectra. This additional\nnoise contribution has a maximum at the quantum dot resonance and shows a\nsignificantly longer correlation time. Magnetic-field-dependent measurements in\ncombination with theoretical modeling prove that this additional noise\ncontribution unveils a charge reoccupation noise which is intrinsic in\nnaturally charged quantum dots.",
        "positive": "Highly efficient phase-tunable photonic thermal diode: We investigate the photon-mediated thermal transport between a\nsuperconducting electrode and a normal metal. When the quasiparticle\ncontribution can be neglected, the photon-mediated channel becomes an efficient\nheat transport relaxation process for the superconductor at low temperatures,\nbeing larger than the intrinsic contribution due to the electron-phonon\ninteraction. Furthermore, the superconductor-normal metal system acts as a\nnearly-perfect thermal diode, with a rectification factor up to $10^8$ for a\nrealistic aluminum superconducting island. The rectification factor can be also\ntuned in a phase-controlled fashion through a non-galvanic coupling, realized\nby changing the magnetic flux piercing a superconducting quantum interference\ndevice (SQUID), which modifies the coupling impedance between the\nsuperconductor and the normal metal. The scheme can be exploited for passive\ncooling in superconducting quantum circuits by transferring heat toward normal\nmetallic pads where it dissipates more efficiently or for more general thermal\nmanagement purposes."
    },
    {
        "anchor": "Spin-wave instabilities in spin-transfer-driven magnetization dynamics: We study the stability of magnetization precessions induced in spin-transfer\ndevices by the injection of spin-polarized electric currents. Instability\nconditions are derived by introducing a generalized, far-from-equilibrium\ninterpretation of spin-waves. It is shown that instabilities are generated by\ndistinct groups of magnetostatically coupled spin-waves. Stability diagrams are\nconstructed as a function of external magnetic field and injected\nspin-polarized current. These diagrams show that applying larger fields and\ncurrents has a stabilizing effect on magnetization precessions. Analytical\nresults are compared with numerical simulations of spin-transfer-driven\nmagnetization dynamics.",
        "positive": "Observation of quantum corrections to conductivity up to optical\n  frequencies: It is well known that conductivity of disordered metals is suppressed in the\nlimit of low frequencies and temperatures by quantum corrections. Although\npredicted by theory to exist up to much higher energies, such corrections have\nso far been experimentally proven only for $\\lesssim$80 meV. Here, by a\ncombination of transport and optical studies, we demonstrate that the quantum\ncorrections are present in strongly disordered conductor MoC up to at least\n$\\sim$4 eV, thereby extending the experimental window where such corrections\nwere found by a factor of 50. The knowledge of both, the real and imaginary\nparts of conductivity, enables us to identify the microscopic parameters of the\nconduction electron fluid. We find that the conduction electron density of\nstrongly disordered MoC is surprisingly high and we argue that this should be\nconsidered a generic property of metals on the verge of disorder-induced\nlocalization transition."
    },
    {
        "anchor": "Ultrafast Magnetization Reversal by Picosecond Electrical Pulses: The field of spintronics involves the study of both spin and charge transport\nin solid state devices with a view toward increasing their functionality and\nefficiency. Alternatively, the field of ultrafast magnetism focuses on the use\nof femtosecond laser pulses to excite electrons in magnetic materials, which\nallows the magnetic order to be dramatically changed on unprecedented\nsub-picosecond time-scales. Here, we unite these two distinct research\nactivities by using picosecond electrical pulses to rapidly excite electrons in\na magnetic metal. We are able to deterministically and repetitively reverse the\nmagnetization of a GdFeCo film with sub-10 picosecond electrical pulses. The\nmagnetization reverses in ~10ps, which is more than an order of magnitude\nfaster than any other electrically controlled magnetic switching. We attribute\nthe deterministic switching of the magnetization to ultrafast excitation of the\nelectrons, a fundamentally different mechanism from other current driven\nswitching mechanisms such as spin-transfer-torque (STT) or spin-orbit-torque\n(SOT). The energy density required for switching is measured and the process is\nfound to be efficient, projecting to only 4 fJ needed to switch a (20 nm)^3\ncell, which is comparable to other state-of-the-art STT-MRAM memory devices.\nThis discovery will launch a new field of research into picosecond spintronic\nphenomena and devices.",
        "positive": "Higher Chern Number States in Curved Periodic Nanowires: The coupling between the spin and momentum degrees of freedom due to\nspin-orbit interactions (SOI) suggests that the strength of the latter can be\nmodified by controlling the motion of the charge carriers. In this paper, we\ninvestigate how the effective SOI can be modulated by constraining the motion\nof charge carriers to curved waveguides thereby introducing real-space\ngeometric curvature in their motion. The change in the SOI can in turn induce\ntopological phase transitions in the system. Specifically, we study how the\nintroduction of periodic sinusoidal curvature in nanowires with intrinsic SOC\ncan induce the onset of mid-gap topologically protected edge states, which can\nbe characterized by a topological invariant or Chern number. The Chern number\ncorresponds to the number of discrete charges that would be pumped across the\nlength of the nanowire when the phase of a sliding gate potential relative to\nthat of the sinusoidal curvature is varied adiabatically over a complete\nperiod. In addition, coupling to an external magnetization can be utilized as\nan experimental knob to modify the Chern number by changing the ordering of the\nnanowire energy bands. The magnetization can be tuned to achieve large discrete\njumps in the number of pump charges per phase period."
    },
    {
        "anchor": "Evolution of photo-excited carrier distribution from anisotropic to\n  isotropic and isotropic photon absorption in graphene: Femtosecond time-resolved spectroscopy using 400 nm-pump and 800 nm-probe in\nCVD-grown multilayer graphene provides strong evidence for isotropic\ndistribution of photoexcited carrier after initial relaxation. Indicative of\nsuch isotropic distribution is a pump polarization independence of differential\nreflectivity (\\DeltaR/R) and transmittance (\\DeltaT/T) from pump-probe\nmeasurements. Combined with results using 800 nm-pump in [arXiv. 1301.1743v3\n(2013)], these pump polarization dependences of time-resolved spectroscopy\ncorroborates the evolution of photo-excited carrier distribution from\nanisotropic to isotropic with carrier relaxation. And, the absorbance of\ngraphene is identical for in-plane and out-of-plane optical fields. No matter\nthe carrier distribution in momentum space, the influence of carrier on\nin-plane and out-of-plane optical fields from state filling effect is\nidentical. The sign reversing of ps dynamics signal in graphene/graphite should\nnot directly relate to carrier.",
        "positive": "Networks of ABA and ABC stacked graphene on mica observed by scanning\n  tunneling microscopy: Graphene flakes are prepared on freshly cleaved mica by exfoliation and\nstudied by scanning tunneling microscopy in ultra high vacuum. On few-layer\ngraphene, a triangular network of partial dislocations separating ABC stacked\nand ABA stacked graphene was found similar to the networks occasionally visible\non freshly cleaved HOPG. We found differences in the electronic structure of\nABC and ABA stacked areas by scanning tunneling spectroscopy, i.e., a\npronounced peak at 0.25 eV above the Fermi level exclusively in the ABA areas,\nwhich is shown to be responsible for the different apparent heights observed in\nSTM images."
    },
    {
        "anchor": "Nonequilibrium current driven by a step voltage pulse: an exact solution: One of the most important problems in nanoelectronic device theory is to\nestimate how fast or how slow a quantum device can turn on/off a current. For\nan arbitrary noninteracting phase-coherent device scattering region connected\nto the outside world by leads, we have derived an exact solution for the\nnonequilibrium, nonlinear, and time-dependent current driven by both up- and\ndown-step pulsed voltages. Our analysis is based on the Keldysh nonequilibrium\nGreen's functions formalism where the electronic structure of the leads as well\nas the scattering region are treated on an equal footing. A model calculation\nfor a quantum dot with a Lorentzian linewidth function shows that the\ntime-dependent current dynamics display interesting finite-bandwidth effects\nnot captured by the commonly used wideband approximation.",
        "positive": "Aharonov-Casher effect in Bi$_{\\rm 2}$Se$_{\\rm 3}$ square-ring\n  interferometers: Electrical control of spin dynamics in Bi$_{\\rm 2}$Se$_{\\rm 3}$ was\ninvestigated in ring-type interferometers. Aharonov-Bohm and\nAltshuler-Aronov-Spivak resistance oscillations against magnetic field, and\nAharorov-Casher resistance oscillations against gate voltage were observed in\nthe presence of a Berry phase of $\\pi$. A very large tunability of spin\nprecession angle by gate voltage has been obtained, indicating that Bi$_{\\rm\n2}$Se$_{\\rm 3}$-related materials with strong spin-orbit coupling are promising\ncandidates for constructing novel spintronic devices."
    },
    {
        "anchor": "Strain Mapping In Single-Layer 2D Crystals Via Raman Activity: By performing density functional theory-based ab-initio calculations, Raman\nactive phonon modes of novel single-layer two-dimensional (2D) materials and\nthe effect of in-plane biaxial strain on the peak frequencies and corresponding\nactivities of the Raman active modes are calculated. Our findings confirm the\nRaman spectrum of the unstrained 2D crystals and provide expected variations in\nthe Raman active modes of the crystals under in-plane biaxial strain. The\nresults are summarized as follows; (i) frequencies of the phonon modes soften\n(harden) under applied tensile (compressive) strains, (ii) the response of the\nRaman activities to applied strain for the in-plane and out-of-plane\nvibrational modes have opposite trends, thus, the built-in strains in the\nmaterials can be monitored by tracking the relative activities of those modes,\n(iii) in particular, the A-peak in single-layer Si and Ge disappear under a\ncritical tensile strain, (iv) especially in mono and di- atomic single-layers,\nthe shift of the peak frequencies is stronger indication of the strain rather\nthan the change in Raman activities, (v) Raman active modes of single-layer ReX\n2 (X=S, Se) are almost irresponsive to the applied strain. Strain-induced\nmodifications in the Raman spectrum of 2D materials in terms of the peak\npositions and the relative Raman activities of the modes could be a convenient\ntool for characterization.",
        "positive": "Selective Spin Injection Controlled by Electrical way in\n  Ferromagnet/Quantum Dot/Semiconductor system: Selective and large polarization of current injected into semiconductor (SC)\nis predicted in Ferromagnet (FM)/Quantum Dot (QD)/SC system by varying the gate\nvoltage above the Kondo temperature. In addition, spin-dependent Kondo effect\nis also revealed below Kondo temperature. It is found that Kondo resonances for\nup spin state is suppressed with increasing of the polarization P of the FM\nlead. While the down one is enhanced. The Kondo peak for up spin is disappear\nat P=1."
    },
    {
        "anchor": "Quantum interference and weak localisation effects in the interlayer\n  magnetoresistance of layered metals: Studies of angle-dependent magnetoresistance oscillations (AMRO) in the\ninterlayer conductivity of layered metals have generally considered\nsemi-classical electron transport. We consider a quantum correction to the\nsemi-classical conductivity that arises from what can be described as an\ninterlayer Cooperon. This depends on both the disorder potential within a layer\nand the correlations of the disorder potential between layers. We compare our\nresults with existing experimental data on organic charge transfer salts that\nare not explained within the standard semi-classical transport picture. In\nparticular, our results may be applicable to effects that have been seen when\nthe applied magnetic field is almost parallel to the conducting layers. We\npredict the presence of a peak in the resistivity as the field direction\napproaches the plane of the layers. The peak can occur even when there is\nweakly incoherent transport between layers.",
        "positive": "Orbital magnetic susceptibility of finite-sized graphene: We study the orbital magnetism of graphene ribbon in the effective-mass\napproximation, to figure out the finite-size effect on the singular\nsusceptibility known in the bulk limit. We find that the susceptibility at T =\n0 oscillates between diamagnetism and paramagnetism as a function of Fermi\nenergy, in accordance with the subband structure formed by quantum confinement.\nIn increasing T, the oscillation rapidly disappears once the thermal broadening\nenergy exceeds the subband spacing, and the susceptibility approaches the bulk\nlimit i.e., a thermally broadened diamagnetic peak centered at zero energy\npoint. The electric current supporting the diamagnetism is found to flow near\nthe edge with a depth which proportional to reciprocal of T, with v being the\nband velocity, while at T = 0 the current distribution spreads entirely in the\nsample reflecting the absence of the characteristic wavelength in graphene. The\nresult is applied to estimate the three-dimensional random-stacked multilayer\ngraphene, where we show that the external magnetic field is significantly\nscreened inside the sample in low temperatures, in a much stronger manner than\nin graphite."
    },
    {
        "anchor": "Localization of low-frequency oscillations in single-walled carbon\n  nanotubes. Supplementary materials: In this supplement we present a short derivation of dynamical equations of\nthin elastic shell in the framework of modified nonlinear Sanders-Koiter\ntheory, and their relationship with the dynamics of one-dimensional oscillatory\nchain.",
        "positive": "Coulomb blockade and Kondo effect in quantum dots: We review the mechanisms of low-temperature electron transport across a\nquantum dot weakly coupled to two conducting leads. Conduction in this case is\ncontrolled by the interaction between electrons. At temperatures moderately\nlower than the single-electron charging energy of the dot, the linear\nconductance is suppressed by the Coulomb blockade. Upon further lowering of the\ntemperature, however, the conductance may start to increase again due to the\nKondo effect. This increase occurs only if the dot has a non-zero spin S. We\nconcentrate on the simplest case of S=1/2, and discuss the conductance across\nthe dot in a broad temperature range, which includes the Kondo temperature.\nTemperature dependence of the linear conductance in the Kondo regime is\ndiscussed in detail. We also consider a simple (but realistic) limit in which\nthe differential conductance at a finite bias can be fully investigated."
    },
    {
        "anchor": "First-Principles Study of Substitutional Metal Impurities in Graphene:\n  Structural, Electronic and Magnetic Properties: We present a theoretical study using density functional calculations of the\nstructural, electronic and magnetic properties of 3d transition metal, noble\nmetal and Zn atoms interacting with carbon monovacancies in graphene. We pay\nspecial attention to the electronic and magnetic properties of these\nsubstitutional impurities and found that they can be fully understood using a\nsimple model based on the hybridization between the states of the metal atom,\nparticularly the d shell, and the defect levels associated with an\nunreconstructed D3h carbon vacancy. We identify three different regimes\nassociated with the occupation of different carbon-metal hybridized electronic\nlevels:\n  (i) bonding states are completely filled for Sc and Ti, and these impurities\nare non-magnetic;\n  (ii) the non-bonding d shell is partially occupied for V, Cr and Mn and,\ncorrespondingly, these impurties present large and localized spin moments;\n  (iii) antibonding states with increasing carbon character are progressively\nfilled for Co, Ni, the noble metals and Zn. The spin moments of these\nimpurities oscillate between 0 and 1 Bohr magnetons and are increasingly\ndelocalized.\n  The substitutional Zn suffers a Jahn-Teller-like distortion from the C3v\nsymmetry and, as a consequence, has a zero spin moment. Fe occupies a distinct\nposition at the border between regimes (ii) and (iii) and shows a more complex\nbehavior: while is non-magnetic at the level of GGA calculations, its spin\nmoment can be switched on using GGA+U calculations with moderate values of the\nU parameter.",
        "positive": "Mesoscopic fluctuations of the local density of states in interacting\n  electron systems: We review our recent theoretical results for mesoscopic fluctuations of the\nlocal density of states in the presence of electron-electron interaction. We\nfocus on the two specific cases: (i) a vicinity of interacting critical point\ncorresponding to Anderson-Mott transition, and (ii) a vicinity of\nnon-interacting critical point in the presence of a weak electron-electron\nattraction. In both cases strong mesoscopic fluctuations of the local density\nof states exist."
    },
    {
        "anchor": "Topological one-way fiber of second Chern number: Optical fiber is a ubiquitous and indispensable component in communications,\nsensing, biomedicine and many other lightwave technologies and applications.\nHere we propose topological one-way fibers to remove two fundamental mechanisms\nthat limit fiber performance: scattering and reflection. We design\nthree-dimensional~(3D) photonic crystal fibers, inside which photons propagate\nonly in one direction, that are completely immune to Rayleigh and Mie\nscatterings and significantly suppress the nonlinear Brillouin and Raman\nscatterings. A one-way fiber is also free from Fresnel reflection, naturally\neliminating the needs for fiber isolators. Our finding is enabled by the\nrecently discovered Weyl points in a double-gyroid~(DG) photonic crystal. By\nannihilating two Weyl points by supercell modulation in a magnetic DG, we\nobtain the photonic analogue of the 3D quantum Hall phase with a non-zero first\nChern number~($C_1$). When the modulation becomes helixes, one-way fiber modes\ndevelop along the winding axis, with the number of modes determined by the\nspatial frequency of the helix. These single-polarization single-mode and\nmulti-mode one-way fibers, having nearly identical group and phase velocities,\nare topologically-protected by the second Chern number~($C_2$) in the 4D\nparameter space of the 3D wavevectors plus the winding angle of the helixes.\nThis work suggests a unique way to utilize higher-dimensional topological\nphysics without resorting to artificial dimensions.",
        "positive": "All-magnetic control of skyrmions in nanowires by a spin wave: Magnetic skyrmions are topologically protected nanoscale objects, which are\npromising building blocks for novel magnetic and spintronic devices. Here, we\ninvestigate the dynamics of a skyrmion driven by a spin wave in a magnetic\nnanowire. It is found that (i) the skyrmion is first accelerated and then\ndecelerated exponentially; (ii) it can turn L-corners with both right and left\nturns; and (iii) it always turns left (right) when the skyrmion number is\npositive (negative) in the T- and Y-junctions. Our results will be the basis of\nskyrmionic devices driven by a spin wave."
    },
    {
        "anchor": "Giant negative magnetoresistance induced by the chiral anomaly in\n  individual Cd3As2 nanowires: Cd3As2 is a newly booming Dirac semimetal with linear dispersion along all\nthree momentum directions and can be viewed as 3D analog of graphene. As\nbreaking of either time reversal symmetry or spatial inversion symmetry, the\nDirac semimetal is believed to transform into Weyl semimetal with exotic chiral\nanomaly effect, while the experimental evidence of the chiral anomaly is still\nmissing in Cd3As2. Here we report the magneto-transport properties of\nindividual Cd3As2 nanowires. Large negative magnetoresistance (MR) with\nmagnitude of -63% at 60 K and -11% at 300 K are observed when the magnetic\nfield is parallel with the electric field direction, giving the evidence of the\nchiral magnetic effect in Cd3As2 nanowires. In addition, the critical magnetic\nfield BC, where there is an extremum of the negative MR, increases with\nincreasing temperature. As the first observation of chiral anomaly induced\nnegative MR in Cd3As2 nanowires, it may offer valuable insights for low\ndimensional physics in Dirac semimetals.",
        "positive": "The General Principle behind Magnetization-induced Second-Order\n  Topological Corner States in the Kane-Mele Model: We propose a general principle for realizing second-order topological corner\nstates in the modified Kane-Mele model with magnetization. It is demonstrated\nthat the sign of the edge Dirac mass depends on the magnetization of the edge\nsublattice termination. By adjusting the directions of magnetization according\nto the type of sublattice at the termination of two edges, a mass domain wall\ncan be induced in the presence of topological corner states at an arbitrary\nposition. All previous work on introducing magnetization in the Kane-Mele model\nto realize second-order topological corner states can be explained by the\npresence of the Dirac mass domain wall with opposite signs. Applying this\nprinciple, we design square-shaped and armchair-type hexagon-shaped graphene\nnanoflakes with edge magnetization, allowing for the emergence of second-order\ntopological corner states. Our findings serve as a general theory,\ndemonstrating that the realization of second-order topological corner states is\nnot limited by boundary type or nanoflake shape."
    },
    {
        "anchor": "Defect Controlled Ferromagnetic Ordering in Au Implanted TiSe$_2$\n  Nanocrystals: Layered transition metal dichalcogenides (TMDs) are attracting increasing\nattention because they exhibit unconventional magnetic properties due to\ncrystal imperfections in their usually non-magnetic 2D structure. This work\naims to investigate the magnetic response of self-engineered Se deficient\nTiSe$_2$ thin films, synthesized using chemical vapour deposition. We\ndemonstrate tunability of the ferromagnetic order with the introduction of Au\natoms using low energy Au ion implantation, which works as a controlling knob\nto vary the stoichiometry of Se in TiSe$_{2-x}$. The corresponding isothermal\nfield-magnetization curves fit well with a modified Brillouin J function with J\nvalue of 1.5 for Ti$^{3+}$, and 4 for Au$^{3+}$, accounting for the\ndiamagnetism that arises from Au implantation. We propose a qualitative model\nfor the experimentally observed magnetization as a function of ion fluence,\ncorroborated with high-resolution transmission electron microscopy. Depending\non the Au nanoparticle size in the implanted samples, magnetization saturates\nfaster at a much lower applied magnetic field than the pristine sample. Our\nfindings hold potential to expand the range of 2D ferromagnetic materials for\nspintronics and magnetic sensing applications.",
        "positive": "Low-symmetry nanowire cross-sections for enhanced Dresselhaus spin-orbit\n  interaction: We study theoretically the spin-orbit interaction of low-energy electrons in\nsemiconducting nanowires with a zinc-blende lattice. The effective Dresselhaus\nterm is derived for various growth directions, including <11(-2)>-oriented\nnanowires. While a specific configuration exists where the Dresselhaus\nspin-orbit coupling is suppressed even at confinement potentials of low\nsymmetry, many configurations allow for a strong Dresselhaus coupling. In\nparticular, we discuss qualitative and quantitative results for nanowire\ncross-sections modeled after sectors of rings or circles. The parameter\ndependence is analyzed in detail, enabling predictions for a large variety of\nsetups. For example, we gain insight into the spin-orbit coupling in recently\nfabricated GaAs-InAs nanomembrane-nanowire structures. By combining the\neffective Dresselhaus and Rashba terms, we find that such structures are\npromising platforms for applications where an electrically controllable\nspin-orbit interaction is needed. If the nanowire cross-section is scaled down\nand InAs replaced by InSb, remarkably high Dresselhaus-based spin-orbit\nenergies of the order of millielectronvolt are expected. A Rashba term that is\nsimilar to the effective Dresselhaus term can be induced via electric gates,\nproviding means to switch the spin-orbit interaction on and off. By varying the\ncentral angle of the circular sector, we find, among other things, that\nparticularly strong Dresselhaus couplings are possible when nanowire\ncross-sections resemble half-disks."
    },
    {
        "anchor": "The tunneling density-of-states of interacting massless Dirac fermions: We calculate the tunneling density-of-states (DOS) of a disorder-free\ntwo-dimensional interacting electron system with a massless-Dirac band\nHamiltonian. The DOS exhibits two main features: i) linear growth at large\nenergies with a slope that is suppressed by quasiparticle velocity enhancement,\nand ii) a rich structure of plasmaron peaks which appear at negative bias\nvoltages in an n-doped sample and at positive bias voltages in a p-doped\nsample. We predict that the DOS at the Dirac point is non-zero even in the\nabsence of disorder because of electron-electron interactions, and that it is\nthen accurately proportional to the Fermi energy. The finite background DOS\nobserved at the Dirac point of graphene sheets and topological insulator\nsurfaces can therefore be an interaction effect rather than a disorder effect.",
        "positive": "Tunable symmetry breaking and helical edge transport in a graphene\n  quantum spin Hall state: Low-dimensional electronic systems have traditionally been obtained by\nelectrostatically confining electrons, either in heterostructures or in\nintrinsically nanoscale materials such as single molecules, nanowires, and\ngraphene. Recently, a new paradigm has emerged with the advent of\nsymmetry-protected surface states on the boundary of topological insulators,\nenabling the creation of electronic systems with novel properties. For example,\ntime reversal symmetry (TRS) endows the massless charge carriers on the surface\nof a three-dimensional topological insulator with helicity, locking the\norientation of their spin relative to their momentum. Weakly breaking this\nsymmetry generates a gap on the surface, resulting in charge carriers with\nfinite effective mass and exotic spin textures. Analogous manipulations of the\none-dimensional boundary states of a two-dimensional topological insulator are\nalso possible, but have yet to be observed in the leading candidate materials.\nHere, we demonstrate experimentally that charge neutral monolayer graphene\ndisplays a new type of quantum spin Hall (QSH) effect, previously thought to\nexist only in TRS topological insulators, when it is subjected to a very large\nmagnetic field angled with respect to the graphene plane. Unlike in the TRS\ncase, the QSH presented here is protected by a spin-rotation symmetry that\nemerges as electron spins in a half-filled Landau level are polarized by the\nlarge in-plane magnetic field. The properties of the resulting helical edge\nstates can be modulated by balancing the applied field against an intrinsic\nantiferromagnetic instability, which tends to spontaneously break the\nspin-rotation symmetry. In the resulting canted antiferromagnetic (CAF) state,\nwe observe transport signatures of gapped edge states, which constitute a new\nkind of one-dimensional electronic system with tunable band gap and associated\nspin-texture."
    },
    {
        "anchor": "Topological Toda lattice and nonlinear bulk-edge correspondence: The Toda lattice is a model of nonlinear wave equations allowing exact\nsoliton solutions. It is realized by an electric circuit made of a transmission\nline with variable capacitance diodes and inductors. It has been generalized to\nthe dimerized Toda lattice by introducing alternating bondings specified by a\ncertain parameter $\\lambda $, where it is reduced to the Toda lattice at\n$\\lambda =0$. In this work, we investigate the topological dynamics of the\nvoltage along the transmission line. It is demonstrated numerically that the\nsystem is topological for $\\lambda <0$, while it is trivial for $\\lambda >0$\nwith the phase transition point given by the original Toda lattice ($\\lambda\n=0$). These topological behaviors are well explained by the chiral index\nfamiliar in the Su-Schrieffer-Heeger model. The topological phase transition is\nobservable by a significant difference between the dynamics of voltages in the\ntwo phases, which is explained by the emergence of the topological edge states.\nThis is a bulk-edge correspondence in nonlinear systems. The dimerized Toda\nlattice is adiabaticaly connected to a linear system, which would be the reason\nwhy the topological arguments are valid. Furthermore, we show that the\ntopological edge state is robust against randomness.",
        "positive": "Negative dynamic Drude conductivity in pumped graphene: We theoretically reveal a new mechanism of light amplification in graphene\nunder the conditions of interband population inversion. It is enabled by the\nindirect interband transitions, with the photon emission preceded or followed\nby the scattering on disorder. The emerging contribution to the optical\nconductivity, which we call the interband Drude conductivity, appears to be\nnegative for the photon energies below the double quasi-Fermi energy of pumped\nelectrons and holes. We find that for the Gaussian correlated distribution of\nscattering centers, the real part of the net Drude conductivity (interband plus\nintraband) can be negative in the terahertz and near-infrared frequency ranges,\nwhile the radiation amplification by a single graphene sheet can exceed 2.3%."
    },
    {
        "anchor": "Switching probability of all-perpendicular spin valve nanopillars: In all-perpendicular spin valve nanopillars the probability density of the\nfree-layer magnetization is independent of the azimuthal angle and its\nevolution equation simplifies considerably compared to the general,\nnonaxisymmetric geometry. Expansion of the time-dependent probability density\nto Legendre polynomials enables analytical integration of the evolution\nequation and yields a compact expression for the practically relevant switching\nprobability. This approach is valid when the free layer behaves as a\nsingle-domain magnetic particle and it can be readily applied to fitting\nexperimental data.",
        "positive": "Unusual electronic properties of clean and disordered zigzag graphene\n  nanoribbons: We revisit the problem of electron transport in clean and disordered zigzag\ngraphene nanoribbons, and expose numerous hitherto unknown peculiar properties\nof these systems at zero energy, where both sublattices decouple because of\nchiral symmetry. For clean ribbons, we give a quantitative description of the\nunusual power-law dispersion of the central energy bands and of its main\nconsequences, including the strong divergence of the density of states near\nzero energy, and the vanishing of the transverse localization length of the\ncorresponding edge states. In the presence of off-diagonal disorder, which\nrespects the lattice chiral symmetry, all zero-energy localization properties\nare found to be anomalous. Recasting the problem in terms of coupled Brownian\nmotions enables us to derive numerous asymptotic results by analytical means.\nIn particular the typical conductance $g_N$ of a disordered sample of width $N$\nand length $L$ is shown to decay as $\\exp(-C_Nw\\sqrt{L})$, for arbitrary values\nof the disorder strength $w$, while the relative variance of $\\ln g_N$\napproaches a non-trivial constant $K_N$. The dependence of the constants $C_N$\nand $K_N$ on the ribbon width $N$ is predicted. From the mere viewpoint of the\ntransfer-matrix formalism, zigzag ribbons provide a case study with many\nunusual features. The transfer matrix describing propagation through one unit\ncell of a clean ribbon is not diagonalizable at zero energy. In the disordered\ncase, we encounter non-trivial random matrix products such that all Lyapunov\nexponents vanish identically."
    },
    {
        "anchor": "Kinetic Monte Carlo Model of Breakup of Nanowires into Chains of\n  Nanoparticles: A kinetic Monte Carlo approach is applied to studying shape instability of\nnanowires that results in their breaking up into chains of nanoparticles. Our\napproach can be used to explore dynamical features of the process that\ncorrespond to experimental findings, but that cannot be interpreted by\ncontinuum mechanisms reminiscent of the description of the Plateau-Rayleigh\ninstability in liquid jets. For example, we observe long-lived dumbbell-type\nfragments and other typical non-liquid-jet characteristics of the process, as\nwell as confirm the observed lattice-orientation dependence of the breakup\nprocess of single-crystal nanowires. We provide snapshots of the process\ndynamics, and elaborate on the nanowire-end effects, as well as on the\nmorphology of the resulting nanoparticles.",
        "positive": "Missing Shapiro steps and the $8\u03c0$-periodic Josephson effect in\n  interacting helical electron systems: Two-particle backscattering in time-reversal invariant interacting helical\nelectron systems can lead to the formation of quasiparticles with charge $e/2$.\nWe propose a way to detect such states by means of the Josephson effect in the\npresence of proximity-induced superconductivity. In this case, the existence of\n$e/2$ charges leads to an $8 \\pi$-periodic component of the Josephson current\nwhich can be identified through measurement of Shapiro steps in Josephson\njunctions. In particular, we show that even when there is weak explicit\ntime-reversal symmetry breaking, which causes the two-particle backscattering\nto be a sub-leading effect at low energies, its presence can still be detected\nin driven, current-biased Shapiro step measurements. The disappearance of some\nof these steps as a function of the drive frequency is directly related to the\nexistence of non-Abelian zero-energy states. We suggest that this effect can be\nmeasured in current state-of-the-art Rashba wires."
    },
    {
        "anchor": "Time-domain measurements of quasiparticle tunneling rates in a\n  single-Cooper-pair transistor: We have measured, in real time, individual quasiparticle tunneling in a\nsingle Cooper pair transistor, using rf reflectometry on the supercurrent\nbranch. We have extracted the even-to-odd and odd-to-even transition rates\ndirectly by analyzing the distributions of dwell times in the even and odd\nstates of the transistor. We discuss both the measurement and analysis\ntechniques and report on the temperature and gate dependence of the\nquasiparticle tunneling rates.",
        "positive": "Transmission Phase of a Quantum Dot with Kondo Correlation Near the\n  Unitary Limit: The complex transmission amplitude -- both magnitude and phase -- of a\nquantum dot (QD) with Kondo correlation was measured near the unitary limit.\nContrary to previous phase measurements, performed far from this limit [Ji et\nal., Science 290, 779 (2000)], the transmission phase was observed to evolve\nlinearly over a range of about 1.5 pi when the Fermi energy was scanned through\na Kondo pair -- a pair of spin degenerate energy levels. Moreover, the phase in\nCoulomb blockade (CB) peak, adjancent to the Kondo pair, retained a memory of\nthe Kondo correlation and did not exhibit the familiar behavior in the CB\nregime. These results do not agree with theoretical predictions, suggesting\nthat a full explanation may go beyond the framework of the Anderson model."
    },
    {
        "anchor": "Spin rectification for collinear and non-collinear magnetization and\n  external magnetic field configurations: Spin rectification in a single crystal Fe/Au/Fe sandwich is electrically\ndetected for collinear and non-collinear magnetization and external magnetic\nfield configurations. The line shape, line width and signal polarity are\nanalysed. The spin rectication theory has been much extended by taking the\nmagneto-crystalline anisotropy and shape anisotropy into account, which\nexplained non-collinear resonances and agrees very well with experimental data.\nThus, a comprehensive understanding of spin rectification in ferromagnetic\nmetal was demonstrated in this work.",
        "positive": "NMR evidence for energy gap opening in thiol-capped platinum\n  nanoparticles: When the particle size of a metal is reduced, it is expected that an energy\ngap will open due to the quantum size effect. However, the energy gap in\nplatinum (Pt) metal nanoparticles has not been observed directly by nuclear\nmagnetic resonance (NMR). To investigate the particle size dependence of the\nelectronic state of Pt nanoparticles, we performed 195Pt NMR experiments on\nthiol-capped Pt nanoparticles with three different average diameters of less\nthan 3 nm. For the nanoparticles with a diameter of 2.8 nm, we observed usual\nmetallic behavior with a smaller density of states than that of the bulk Pt. In\ncontrast, the temperature dependence of 1/T1T in nanoparticles less than 2.5 nm\nin diameter is an activation-energy form above 150 K, which is semiconducting\nbehavior with an energy gap of the order of 2000 K. The significant decrease in\n1/T1T by more than two orders of magnitude in the smaller Pt nanoparticles\ncompared to the bulk Pt is attributable to the disappearance of the density of\nstates at the Fermi energy, which is consistent with the opening of an energy\ngap. These results indicate a metal-insulator transition below 2.5 nm in\ndiameter is present in our thiol-capped Pt nanoparticle samples. The effect of\nthe thiol capping on the electronic structure suggested by the experimental\nresults is also discussed."
    },
    {
        "anchor": "Symmetry-enforced nodal lines in the band structures of\n  vacancy-engineered graphene: We elaborate that single-layer graphene with periodic vacancies can have a\nband structure containing nodal lines or nodal loops, opening the possibility\nof graphene-based electronic or spintronic devices with novel functionalities.\nThe principle is that by removing carbon atoms such that the lattice becomes\nnonsymmorphic, every two sublattices in the unit cell will map to each other\nunder glide plane operation. This mapping yields degenerate eigenvalues for the\nglide plane operation, which guarantees that the energy bands must stick\ntogether pairwise at a boundary of the Brillouin zone. Moving away from the\nBrillouin zone boundary causes the symmetry-enforced nodal lines to split,\nresulting in accidental nodal lines caused by the crossings of the split bands.\nMoreover, the density of states at the Fermi level may be dramatically enhanced\nif the nodal lines crosses the Fermi level. The nodal lines occur a variety of\nvacancy configurations even in the presence of Rashba spin-orbit coupling.\nFinally, our theory also explains the nodal loops surrounding the entire\nBrillouin zone of a chevron-type nanoporous graphene fabricated in a recent\nexperiment.",
        "positive": "Nonlinear optical conductivity of a generic two band systems, with\n  application to doped and gapped graphene: We present a general formulation to calculate the dynamic optical\nconductivity, beyond the linear response regime, of any electronic system whose\nquasiparticle dispersion is described by a two band model. Our phenomenological\nmodel is based on the optical Bloch equations. In the steady state regime it\nyields an analytic solution for the population inversion and the interband\ncoherence, which are nonlinear in the optical field intensity, including finite\ndoping and temperature effects. We explicitly show that the optical\nnonlinearities are controlled by a single dimensionless parameter which is\ndirectly proportional to the incident field strength and inversely proportional\nto the optical frequency. This identification leads to a unified way to study\nthe dynamical conductivity and the differential transmission spectrum across a\nwide range of optical frequencies, and optical field strength. We use our\nformalism to analytically calculate the nonlinear optical conductivity of doped\nand gapped graphene, deriving the well known universal ac conductivity of\n$\\sigma_0={e^2}/4\\hbar$ in the linear response regime of low optical\nintensities (or equivalently high frequencies) and non-linear deviations from\nit which appear at high laser intensities (or low frequencies) including the\nimpact of finite doping and band-gap opening."
    },
    {
        "anchor": "Spin switching in semiconductor quantum dots through spin-orbit coupling: The spin-orbit coupling influences the total spin of semiconductor quantum\ndots. We analyze the theoretical prediction for the combined effects of\nspin-orbit coupling, weak vertical magnetic fields and deformation of the dot.\nOur results allow the characterization of the quantum dots as spin switches,\ncontrollable with electric gates.",
        "positive": "Generalized transmon Hamiltonian for Andreev spin qubits: We solve the problem of an interacting quantum dot embedded in a Josephson\njunction between two superconductors with finite charging energy described by\nthe transmon (Cooper pair box) Hamiltonian. The approach is based on the\nflat-band approximation of the Richardson model, which reduces the Hilbert\nspace to the point where exact diagonalisation is possible while retaining all\nstates that are necessary to describe the low energy phenomena. The presented\nmethod accounts for the physics of the quantum dot, the Josephson effect and\nthe Coulomb repulsion (charging energy) at the same level. In particular, it\ncaptures the quantum fluctuations of the superconducting phase as well as the\ncoupling between the superconducting phase and the quantum dot (spin) degrees\nof freedom. The method can be directly applied for modelling Andreev spin\nqubits embedded in transmon circuits in all parameter regimes, for describing\ntime-dependent processes, and for the calculation of transition matrix elements\nfor microwave-driven transmon, spin-flip and mixed transitions that involve\ncoupling to charge or current degree of freedom."
    },
    {
        "anchor": "Non-adiabaticity and single-electron transport driven by surface\n  acoustic waves: Single-electron transport driven by surface acoustic waves (SAW) through a\nnarrow constriction, formed in two-dimensional electron gas, is studied\ntheoretically. Due to long-range Coulomb interaction, the tunneling coupling\nbetween the electron gas and the moving minimum of the SAW-induced potential\nrapidly decays with time. As a result, nonadiabaticiy sets a limit for the\naccuracy of the quantization of acoustoelectric current.",
        "positive": "Exploiting Grids for applications in Condensed Matter Physics: Grids - the collection of heterogeneous computers spread across the globe -\npresent a new paradigm for the large scale problems in variety of fields. We\ndiscuss two representative cases in the area of condensed matter physics\noutlining the widespread applications of the Grids. Both the problems involve\ncalculations based on commonly used Density Functional Theory and hence can be\nconsidered to be of general interest. We demonstrate the suitability of Grids\nfor the problems discussed and provide a general algorithm to implement and\nmanage such large scale problems."
    },
    {
        "anchor": "A model for individual quantal nano-skyrmions: A quantal model description of a discrete localized skyrmion singularity\nembedded in a ferromagnetic environment is proposed. It allows discussing the\nimportance of various parameters in the appearance of a quantal skyrmion\nsingularity. Analysis of the skyrmion reveals a few specific quantal\nproperties: presence of a whole series of skyrmion states, non-classical nature\nof the local spins, presence of superposition states and presence of\nextra-skyrmion states due to the quantization of the central spin of the\nsingularity. The interaction of an electron, tunneling or substrate, with the\nskyrmion is also described allowing a new view at the origin of the skyrmion\nstability as well as the possibility to discriminate between ferromagnetic and\nskyrmion phase in an Inelastic Electron Tunneling Spectroscopy (IETS)\nexperiment, based on the skyrmion quantal properties.",
        "positive": "Fork stamping of pristine carbon nanotubes onto ferromagnetic contacts\n  for spin-valve devices: We present a fabrication scheme called 'fork stamping' optimized for the dry\ntransfer of individual pristine carbon nanotubes (CNTs) onto ferromagnetic\ncontact electrodes fabricated by standard lithography. We demonstrate the\ndetailed recipes for a residue-free device fabrication and in-situ current\nannealing on suspended CNT spin-valve devices with ferromagnetic Permalloy (Py)\ncontacts and report preliminary transport characterization and\nmagnetoresistance experiments at cryogenic temperatures. This scheme can\ndirectly be used to implement more complex device structures, including\nmultiple gates or superconducting contacts."
    },
    {
        "anchor": "Probing topological protected transport in finite-sized\n  Su-Schrieffer-Heeger chains: In order to transport information with topological protection, we reveal and\ndemonstrate experimentally the existence of a characteristic length $L_c$,\ncoined as the transport length, in the bulk size for edge states in\none-dimensional Su-Schrieffer-Heeger (SSH) chains. In spite of the\ncorresponding wavefunction amplitude decays exponentially, characterized by the\npenetration depth $\\xi$, the transport between two edge states remains possible\neven when the lattice size $L$ is much larger than the penetration depth, i.e.,\n$\\xi \\ll L \\le L_c$. Due to the non-zero coupling energy in a finite-size\nsystem, the supported SSH edge states are not completely isolated at the two\nends, giving an abrupt change in the wave localization, manifested through the\ninverse participation ratio to the lattice size. To verify such a\nnon-exponential scaling factor to the system size, we implement a chain of\nsplit-ring resonators and their complementary ones with controllable hopping\nstrengths. By performing the measurements on the group velocity from the\ntransmission spectroscopy of non-trivially topological edge states with pulse\nexcitations, the transport velocity between two edge states is directly\nobserved with the number of lattices up to $20$. Along the route to harness\ntopology to protect optical information, our experimental demonstrations\nprovide a crucial guideline for utilizing photonic topological devices.",
        "positive": "Plasmons in semiconductor and topological insulator wires with large\n  dielectric constant: The dispersion law of plasmons running along thin wires with radius $a$ is\nknown to be practically linear. We show that in a wire with a dielectric\nconstant $\\kappa$ much larger than that of its environment $\\kappa_e$, such\ndispersion law crosses over to a dispersionless three-dimensional-like law when\nthe plasmon wavelength becomes shorter than the length $(a/2)\n\\sqrt{(\\kappa/\\kappa_e)\\ln(\\kappa/2\\kappa_e)}$ at which the electric field\nlines of a point charge exit from the wire to the environment. This happens\nboth in trivial semiconductor wires and wires of three-dimensional topological\ninsulators."
    },
    {
        "anchor": "Magneto-orientation and quantum size effect in SP-STM conductance in the\n  presence of a subsurface magnetic cluster: The influence of a single magnetic cluster in a non-magnetic host metal on\nthe spin current $\\mathbf{j}^{(s)}$ and the charge current $\\mathbf{j}$ in the\nvicinity of a ferromagnetic STM tip is studied theoretically. Spin-flip\nprocesses due to electron interaction with the cluster are taken into account.\nWe show that quantum interference between the partial waves injected from the\nSTM tip and those scattered by the cluster results in the appearance of\ncomponents perpendicular to the initial polarization of the spin current\n$\\mathbf{j}^{(s)}$, which obtain a strongly inhomogeneous spatial distribution.\nThis interference produces oscillations of the conductance as a function of the\ndistance between the contact and the cluster center. The oscillation amplitude\ndepends on the current polarization. We predict a strong magneto-orientational\neffect: the conductance oscillations may grow, shrink, or even vanish for\nrotation of the cluster magnetic moment $\\mathbf{\\mu}_{\\mathrm{eff}}$ by an\nexternal magnetic field. These results can be used for the determination of the\n$ \\mathbf{\\mu}_{\\mathrm{eff}}$ for magnetic clusters below a metal surface.",
        "positive": "Spectroscopic signatures of many-body interactions and delocalized\n  states in self-assembled lateral quantum dot molecules: Lateral quantum dot molecules consist of at least two closely-spaced InGaAs\nquantum dots arranged such that the axis connecting the quantum dots is\nperpendicular to the growth direction. These quantum dot complexes are called\nmolecules because the small spacing between the quantum dots is expected to\nlead to the formation of molecular-like delocalized states. We present optical\nspectroscopy of ensembles and individual lateral quantum dot molecules as a\nfunction of electric fields applied along the growth direction. The results\nallow us to characterize the energy level structure of lateral quantum dot\nmolecules and the spectral signatures of both charging and many-body\ninteractions. We present experimental evidence for the existence of\nmolecular-like delocalized states for electrons in the first excited energy\nshell."
    },
    {
        "anchor": "Electronic transport and device prospects of monolayer molybdenum\n  disulphide grown by chemical vapour deposition: Layered transition metal dichalcogenides display a wide range of attractive\nphysical and chemical properties and are potentially important for various\ndevice applications. Here we report the electronic transport and device\nproperties of monolayer molybdenum disulphide (MoS2) grown by chemical vapour\ndeposition (CVD). We show that these devices have the potential to suppress\nshort channel effects and have high critical breakdown electric field. However,\nour study reveals that the electronic properties of these devices are at\npresent, severely limited by the presence of a significant amount of band tail\ntrapping states. Through capacitance and ac conductance measurements, we\nsystematically quantify the density-of-states and response time of these\nstates. Due to the large amount of trapped charges, the measured effective\nmobility also leads to a large underestimation of the true band mobility and\nthe potential of the material. Continual engineering efforts on improving the\nsample quality are needed for its potential applications.",
        "positive": "On the stability of Laughlin's fractional quantum Hall phase: The fractional quantum Hall effect in 2D electron gases submitted to large\nmagnetic fields remains one of the most striking phenomena in condensed matter\nphysics. Historically, the first observed signature is a Hall resistance\nquantized to the value (2m+1) when the filling factor (electron density divided\nby magnetic flux quantum density) of a 2D electron gas is in the vicinity of an\ninverse odd integer 1/(2m +1). This was one of the first observation of\nfractional quantum numbers. A large part of our basic theoretical understanding\nof this effect (and descendants) originates from Laughlin's theory of 1983,\nreviewed here from a mathematical physics perspective. We explain in which\nsense Laughlin's proposed ground and excited states for the system are\nrigid/incompressible liquids, and why this is crucial for the explanation of\nthe effect."
    },
    {
        "anchor": "Upper bound for the conductivity of nanotube networks: Films composed of nanotube networks have their conductivities regulated by\nthe junction resistances formed between tubes. Conductivity values are enhanced\nby lower junction resistances but should reach a maximum that is limited by the\nnetwork morphology. By considering ideal ballistic-like contacts between\nnanotubes we use the Kubo formalism to calculate the upper bound for the\nconductivity of such films and show how it depends on the nanotube\nconcentration as well as on their aspect ratio. Highest measured conductivities\nreported so far are approaching this limiting value, suggesting that further\nprogress lies with nanowires other than nanotubes.",
        "positive": "Phonon-bottleneck enhanced magnetic hysteresis in a molecular paddle\n  wheel complex of Ru$_2^{5+}$: The ruthenium based molecular magnet\n[Ru$_2$(D(3,5-Cl$_2$Ph)F)$_4$Cl(0.5H$_2$O)$\\cdotp$C$_6$H$_{14}$] (hereafter\nRu$_2$) behaves as a two-level system at sufficiently low temperatures. The\nauthors performed spin detection by means of single-crystal measurements and\nobtained magnetic hysteresis loops around zero bias as a function of field\nsweeping rate. Compared to other molecular systems, Ru$_2$ presents an enhanced\nirreversibility as shown by ``valleys'' of negative differential susceptibility\nin the hysteresis curves. Simulations based on phonon bottleneck model are in\ngood qualitative agreement and suggest an abrupt spin reversal combined with\ninsufficient thermal coupling between sample and cryostat phonon bath."
    },
    {
        "anchor": "Orbital angular momentum and current-induced motion of a\n  Skyrmion-textured domain wall in a ferromagnetic nanotube: We theoretically study the current-induced dynamics of a domain wall in a\nferromagnetic nanotube by developing a theory for the orbital angular momentum\nof a domain wall and the current-induced torque on it. Specifically, a domain\nwall with nontrivial magnetization winding along the circumference is shown to\npossess finite orbital angular momentum, which is proportional to the product\nof its Skyrmion charge and position, and the current is shown to exert a torque\nchanging the orbital angular momentum of the domain wall and thereby drives it.\nThe current-induced torque is interpreted as the transfer of orbital angular\nmomentum from electrons to the domain wall, which occurs due to the emergent\nmagnetic field associated with the Skyrmion charge. Our results reveal a\nhitherto unrecognized utility of the orbital degree of freedom of magnetic\nsolitons.",
        "positive": "A physical model for the reverse leakage current in (In,Ga)N/GaN\n  light-emitting diodes based on nanowires: We investigated the origin of the high reverse leakage current in light\nemitting diodes (LEDs) based on (In,Ga)N/GaN nanowire (NW) ensembles grown by\nmolecular beam epitaxy on Si substrates. To this end, capacitance deep level\ntransient spectroscopy (DLTS) and temperature-dependent current-voltage (I-V)\nmeasurements were performed on a fully processed NW-LED. The DLTS measurements\nreveal the presence of two distinct electron traps with high concentrations in\nthe depletion region of the p-i-n junction. These band gap states are located\nat energies of $570\\pm20$ and $840\\pm30$ meV below the conduction band minimum.\nThe physical origin of these deep level states is discussed. The\ntemperature-dependent I-V characteristics, acquired between 83 and 403 K, show\nthat different conduction mechanisms cause the observed leakage current. On the\nbasis of all these results, we developed a quantitative physical model for\ncharge transport in the reverse bias regime. By taking into account the mutual\ninteraction of variable range hopping and electron emission from Coulombic trap\nstates, with the latter being described by phonon-assisted tunnelling and the\nPoole-Frenkel effect, we can model the experimental I-V curves in the entire\nrange of temperatures with a consistent set of parameters. Our model should be\napplicable to planar GaN-based LEDs as well. Furthermore, possible approaches\nto decrease the leakage current in NW-LEDs are proposed."
    },
    {
        "anchor": "Equilibrium currents in a Corbino graphene ring: We address the description of a graphene Corbino disk in the context of a\ntight binding approach that includes both kinetic and Rashba spin-orbit\ncoupling due to an external out-of-plane electric field. Persistent equilibrium\ncurrents are induced by an external magnetic field breaking time reversal\nsymmetry. By direct diagonalization, we compute the spectrum and focus on the\ndispersion near the $K$ points at the Fermi level. The dispersion keenly\nreproduces that of a continuum model in spite of the complexity of the boundary\nconditions. We validate the assumptions of the continuum model in terms of\npredominant zig-zag boundaries conditions and weak sub-band coupling. The wave\nfunctions displaying the lowest transverse modes are obtained, showing the\npredominance of edge states with charge density at the zig-zag edges. The\npersistent charge currents, nevertheless, do not follow the traditional\nargument of current cancellation from levels below the Fermi level, and thus\nthey depart in the tight-binding from those found in the continuum model.",
        "positive": "Theory of the collective magnetophonon resonance and melting of the\n  field-induced Wigner solid: Electron solid phases of matter are revealed by characteristic vibrational\nresonances. Sufficiently large magnetic fields can overcome the effects of\ndisorder, leading to a weakly pinned collective mode called the magnetophonon.\nConsequently, in this regime it is possible to develop a tightly constrained\nhydrodynamic theory of pinned magnetophonons. The behavior of the magnetophonon\nresonance across thermal and quantum melting transitions has been\nexperimentally characterized in two-dimensional electron systems. Applying our\ntheory to these transitions we explain several key features of the data: (i)\nviolation of the Fukuyama-Lee sum rule as the transition is approached is\ndirectly tied to the non-Lorentzian form taken by the resonance and (ii) the\nnon-Lorentzian shape is caused by characteristic dissipative channels that\nbecome especially important close to melting: proliferating dislocations and\nuncondensed charge carriers."
    },
    {
        "anchor": "Fast thermal relaxation in cavity-coupled graphene bolometers with a\n  Johnson noise read-out: Since the invention of the bolometer, its main design principles relied on\nefficient light absorption into a low-heat-capacity material and its\nexceptional thermal isolation from the environment. While the reduced thermal\ncoupling to its surroundings allows for an enhanced thermal response, it in\nturn strongly reduces the thermal time constant and dramatically lowers the\ndetector's bandwidth. With its unique combination of a record small electronic\nheat capacity and a weak electron-phonon coupling, graphene has emerged as an\nextreme bolometric medium that allows for both, high sensitivity and high\nbandwidths. Here, we introduce a hot-electron bolometer based on a novel\nJohnson noise readout of the electron gas in graphene, which is critically\ncoupled to incident radiation through a photonic nanocavity. This\nproof-of-concept operates in the telecom spectrum, achieves an enhanced\nbolometric response at charge neutrality with a noise equivalent power NEP <\n5pW/ Sqrt(Hz), a thermal relaxation time of {\\tau} < 34ps, an improved light\nabsorption by a factor ~3, and an operation temperature up to T=300K.",
        "positive": "Low-amplitude magnetic vortex core reversal by non-linear interference\n  between azimuthal spin waves and the vortex gyromode: We demonstrate a non-linear interference due to an active 'dual frequency'\nexcitation of both, the sub-GHz vortex gyromode and multi-GHz magneto-static\nspin waves in ferromagnetic micrometer sized platelets in the vortex state.\nWhen the sub-GHz vortex gyromode is excited simultaneously a significant\nbroadband reduction of the switching threshold for spin wave mediated vortex\ncore reversal is observed in both, experiments and micromagnetic simulations.\nConsequently, the magnetic field amplitudes required for vortex core reversal\ncan be lowered by nearly one order of magnitude. Moreover, additional spin wave\nresonance frequencies are found which emerge only if the vortex gyromode is\nactively excited simultaneously which can be explained by frequency doubling\nand by the broken symmetry of the vortex state."
    },
    {
        "anchor": "Spin-orbit gap of graphene: First-principles calculations: Even though graphene is a low energy system consisting of the two dimensional\nhoneycomb lattice of carbon atoms, its quasi-particle excitations are fully\ndescribed by the 2+1 dimensional relativistic Dirac equation. In this paper we\nshow that while the spin-orbit interaction in graphene is of the order of $4\nmeV$, it opens up a gap of the order of $10^{-3} meV$ at the Dirac points. We\npresent the first principle calculation of the spin-orbit gap, and explain the\nbehavior in terms of a simple tight-binding model. Our result also shows that\nthe recently predicted quantum spin Hall effect in graphene can only occur at\nunrealistically low temperature.",
        "positive": "Incidence of multilayers in chemically exfoliated graphene: An efficient route to synthesize macroscopic amounts of graphene is highly\ndesired and a bulk characterization of such samples, in terms of the number of\nlayers, is equally important. We present a Raman spectroscopy-based method to\ndetermine the distribution of the number of graphene layers in chemically\nexfoliated graphene. We utilize a controlled vapor-phase potassium\nintercalation technique and identify a lightly doped stage, where the Raman\nmodes of undoped and doped few-layer graphene flakes coexist. The spectra can\nbe unambiguously distinguished from alkali doped graphite, and a modeling with\nthe distribution of the layers yields an upper limit of flake thickness of five\nlayers with a significant single-layer graphene content. Complementary\nstatistical AFM measurements on individual few-layer graphene flakes find a\nconsistent distribution of the layer numbers."
    },
    {
        "anchor": "Topological states and phase transitions in Sb$_2$Te$_3$-GeTe\n  multilayers: Topological insulators (TIs) are bulk insulators with exotic 'topologically\nprotected' surface conducting modes. It has recently been pointed out that when\nstacked together, interactions between surface modes can induce diverse phases\nincluding the TI, Dirac semimetal, and Weyl semimetal. However, currently a\nfull experimental understanding of the conditions under which topological modes\ninteract is lacking. Here, working with multilayers of the TI Sb$_2$Te$_3$ and\nthe band insulator GeTe, we provide experimental evidence of a multiple\ntopological modes in a single Sb$_2$Te$_3$-GeTe-Sb$_2$Te$_3$ structure.\nFurthermore, we show that reducing the thickness of the GeTe layer induces a\nphase transition from a Dirac-like phase to a gapped phase. By comparing\ndifferent multilayer structures we demonstrate that this transition occurs due\nto the hybridisation of states associated with different TI films. Our results\ndemonstrate that the Sb$_2$Te$_3$-GeTe system offers strong potential towards\nmanipulating topological states as well as towards controlledly inducing\nvarious topological phases.",
        "positive": "Electronic transport on carbon nanotube networks: a multiscale\n  computational approach: Carbon nanotube networks are one of the candidate materials to function as\nmalleable, transparent, conducting films, with the technologically promising\napplication of being used as flexible electronic displays. Nanotubes disorderly\ndistributed in a film offers many possible paths for charge carriers to travel\nacross the entire system, but the theoretical description of how this charge\ntransport occurs is rather challenging for involving a combination of intrinsic\nnanotube properties with network morphology aspects. Here we attempt to\ndescribe the transport properties of such films in two different length scales.\nFirstly, from a purely macroscopic point of view we carry out a geometrical\nanalysis that shows how the network connectivity depends on the nanotube\nconcentration and on their respective aspect ratio. Once this is done, we are\nable to calculate the resistivity of a heavily disordered networked film.\nComparison with experiment offers us a way to infer about the junction\nresistance between neighbouring nanotubes. Furthermore, in order to guide the\nfrantic search for high-conductivity films of nanotube networks, we turn to the\nmicroscopic scale where we have developed a computationally efficient way for\ncalculating the ballistic transport across these networks. While the ballistic\ntransport is probably not capable of describing the observed transport\nproperties of these films, it is undoubtedly useful in establishing an upper\nvalue for their conductivity. This can serve as a guideline in how much room\nthere is for improving the conductivity of such networks."
    },
    {
        "anchor": "Ferromagnetic Behavior of High Purity ZnO nanoparticles: ZnO nanoparticles with Wurtzite structure were prepared by chemical methods\nat low temperature in aqueous solution. Nanoparticles are in the range from\nabout 10 to 30 nm. Ferromagnetic properties were observed from 2 K to room\ntemperature and above. Magnetization vs temperature, M(T) and isothermal\nmeasurements M(H) were determined. The coercive field clearly shows\nferromagnetism above room temperature. The chemical synthesis, structural\ndefects in the bulk related to oxygen vacancies are the main factors for the\nobserved magnetic behavior.\n  PACS numbers: 61.46.Hk Nanocrystals, 75.50.Pp Magnetic semiconductors,\n81.05.Dz II-VI semiconductors",
        "positive": "Effective field theory description of topological crystalline insulators: We propose a phenomenological theory for topological crystalline insulators\nwith time reversal and $C_4$ symmetries. First, we introduce a fictitious space\nand transformation of electromagnetic field operators. This transformation\nleaves the speed of light unchanged but changes the elementary charge to\n$\\sqrt{2}e$. Then we formulate the theory of topological crystalline insulators\nin terms of transformed fields in this fictitious space as 3D BF theory\ncontaining $\\pi$-flux excitations. It is known that a 3D BF theory with half\nflux quantum excitations describes low energy properties of time reversal\ninvariant insulators. By making an inverse transform we recover the effective\nfield theory in original space. It turns out that this field theory contains\nquarter flux quantum excitations."
    },
    {
        "anchor": "A steady state approach for studying valley relaxation using optical\n  vortex beam: Spin-valley coupling in monolayer transition metal dichalcogenides gives rise\nto valley polarization and coherence effect, limited by intervalley scattering\ncaused by exciton-phonon, exciton-impurity, and electron-hole exchange\ninteraction (EHEI). We explore an approach to tune the EHEI by controlling\nexcitons center of mass momentum (COM) utilizing the photon distribution of\nhigher-order optical vortex beam. By virtue of this, we have observed excitons\nCOM-dependent valley depolarization and decoherence which gives us the ability\nto measure the timescale associated with valley dynamics in the steady-state\nmeasurement. Our steady-state technique to probe the valley dynamics can open\nup a new paradigm to explore the physics of excitons in two-dimensional\nsystems.",
        "positive": "Eigenmodes of Neel skyrmions in ultrathin magnetic films: The static and dynamic states of N\\'eel skyrmions in ultrathin ferromagnetic\nfilms with interfacial Dzyaloshinskii-Moriya interaction (DMI) have been\nmicromagnetically simulated as functions of the interfacial DMI strength and\napplied static magnetic field. Findings reveal that while the breathing,\ncounterclockwise (CCW) and clockwise (CW) rotational eigenmodes exist in the\nskyrmion lattice (SkL) phase, only the first two modes are present in the\nisolated skyrmion (ISk) phase. Additionally, the eigenfrequency of the CCW mode\nis insensitive to the magnetic-field driven SkL-ISk phase transition, and the\ninter-skyrmion interaction is largely responsible for exciting the CW mode in\nthe SkL phase. The findings provide physical insight into the dynamics of the\nphase transition and would be of use to potential skyrmion-based microwave\napplications."
    },
    {
        "anchor": "Wave-packet propagation in a finite topological insulator and the\n  spectral localizer index: We consider a model of electrons in a finite topological insulator. We\nnumerically study the propagation of electronic wave-packets localized near\nedges of the structure in the presence of defects and random disorder. We\ncompare the propagation with computations of the \\emph{spectral localizer\nindex}: a spatially local topological index. We find that without disorder,\nwave-packets propagate along boundaries between regions of differing spectral\nlocalizer index with minimal loss, even in the presence of strong defects. With\ndisorder, wave-packets still propagate along boundaries between regions of\ndiffering localizer index, but lose significant mass as they propagate. We also\nfind that with disorder, the \\emph{localizer gap}, a measure of the localizer\nindex \"strength\", is generally smaller away from the boundary than without\ndisorder. Based on this result, we conjecture that wave-packets propagating\nalong boundaries between regions of differing spectral localizer index do not\nlose significant mass whenever the localizer gap is sufficiently large on both\nsides of the boundary.",
        "positive": "Pauli spin blockade with site-dependent g-tensors and spin-polarized\n  leads: Pauli spin blockade (PSB) in double quantum dots (DQDs) has matured into a\nprime technique for precise measurements of nanoscale system parameters. In\nthis work we demonstrate that systems with site-dependent g-tensors and\nspin-polarized leads allow for a complete characterization of the g-tensors in\nthe dots by magnetotransport experiments alone. Additionally, we show that\nspecial polarization configurations can enhance the often elusive\nmagnetotransport signal, rendering the proposed technique robust against noise\nin the system, and inducing a giant magnetoresistance effect. Finally, we\nincorporate the effects of the spin-orbit interaction (SOI) and show that in\nthis case the leakage current contains information about the degree of spin\npolarization in the leads."
    },
    {
        "anchor": "Symmetry-Breaking Interlayer Dzyaloshinskii-Moriya Interactions in\n  Synthetic Antiferromagnets: The magnetic interfacial Dzyaloshinskii-Moriya interaction (DMI) in\nmulti-layered thin films can lead to exotic chiral spin states, of paramount\nimportance for future spintronic technologies. Interfacial DMI is normally\nmanifested as an intralayer interaction, mediated via a paramagnetic heavy\nmetal in systems lacking inversion symmetry. Here we show how, by designing\nsynthetic antiferromagnets with canted magnetization states, it is also\npossible to observe interfacial interlayer-DMI at room temperature. The\ninterlayer-DMI breaks the symmetry of the magnetic reversal process via the\nemergence of noncollinear spin states, which results in chiral exchange-biased\nhysteresis loops. This work opens up yet unexplored avenues for the development\nof new chiral spin textures in multi-layered thin film systems.",
        "positive": "Unveiling quantum Hall transport by Efros-Shklovskii to Mott variable\n  range hopping transition with Graphene: The quantum localization in the quantum Hall regime is revisited using\nGraphene monolayers with accurate measurements of the longitudinal resistivity\nas a function of temperature and current. We experimentally show for the first\ntime a cross-over from Efros-Shklovskii Variable Range Hopping (VRH) conduction\nregime with Coulomb interactions to a Mott VRH regime without interaction. This\noccurs at Hall plateau transitions for localization lengths larger than the\ninteraction screening length set by the nearby gate. Measurements of the\nscaling exponents of the conductance peak widths with both temperature and\ncurrent give the first validation of the Polyakov-Shklovskii scenario that VRH\nalone is sufficient to describe conductance in the Quantum Hall regime and that\nthe usual assumption of a metallic conduction regime on conductance peaks is\nunnecessary."
    },
    {
        "anchor": "Directional Scattering Cancellation for an Electrically Large Dielectric\n  Sphere: We demonstrate the directional scattering cancellation for a dielectric\nsphere of radius up to ten times the incident wavelength, by coating it with a\nsurface of finite conductivity. Specifically, the problem of determining the\nvalues of the surface conductivity that guarantees destructive interference\namong hundreds of multipolar scattering orders at the prescribed angular\ndirection is reduced to the determination of the zeros of a polynomial, whose\ncoefficients are analytically known.",
        "positive": "Quantum Phase Pumping: In this Letter, we consider the adiabatic charge transport through a normal\nmesoscopic sample sandwiched by superconductors without modulation of local\nchemical potentials. The deformation of coherent quasiparticles in the normal\nmetal in the presence of periodically changing phases in the superconductors\nleads to a charge transport. Both the magnitude and the phase dependence of the\ncharge transferred per period through the sample strongly depend on\ntemperature."
    },
    {
        "anchor": "Graphene-based polaritonic crystal: It is shown that monolayer graphene deposited on a spatially-periodic gate\nbehaves as a polaritonic crystal. Its band structure depending on the applied\ngate voltage is studied. The scattering of electromagnetic radiation from such\na crystal is presented calculated and analyzed in terms of Fano-type resonances\nbetween the reflected continuum and plasmon-polariton modes forming narrow\nbands.",
        "positive": "Transport properties of a GaAs/InGaAs/GaAs quantum well: temperature,\n  magnetic field and many-body effects: We investigate the zero and finite temperature transport properties of a\nquasi-two-dimensional electron gas in a GaAs/InGaAs/GaAs quantum well under a\nmagnetic field, taking into account many-body effects via a local-field\ncorrection. We consider the surface roughness, roughness-induced piezoelectric,\nremote charged impurity and homogeneous background charged impurity scattering.\nThe effects of the quantum well width, carrier density, temperature and\nlocal-field correction on resistance ratio are investigated. We also consider\nthe dependence of the total mobility on the multiple scattering effect."
    },
    {
        "anchor": "Effect of a magnetic field on the two-phonon Raman scattering in\n  graphene: We have studied, both experimentally and theoretically, the change of the\nso-called 2D band of the Raman scattering spectrum of graphene (the two-phonon\npeak near 2700 cm-1) in an external magnetic field applied perpendicular to the\ngraphene crystal plane at liquid helium temperature. A shift to lower frequency\nand broadening of this band is observed as the magnetic field is increased from\n0 to 33 T. At fields up to 5--10 T the changes are quadratic in the field while\nthey become linear at higher magnetic fields. This effect is explained by the\ncurving of the quasiclassical trajectories of the photo-excited electrons and\nholes in the magnetic field, which enables us (i) to extract the electron\ninelastic scattering rate, and (ii) to conclude that electronic scattering\naccounts for about half of the measured width of the 2D peak.",
        "positive": "Pseudo-spectral Landau-Lifshitz description of magnetization dynamics: Magnetic materials host a wealth of nonlinear dynamics, textures, and\ntopological defects. This is possible due to the competition between strong\nnonlinearity and dispersion that act at the atomic scale as well as long-range\ninteractions. However, these features are difficult to analytically and\nnumerically study because of the vastly different temporal and spatial scales\ninvolved. Here, we present a pseudo-spectral approach for the Landau-Lifshitz\nequation that invokes energy and momentum conservation embodied in the magnon\ndispersion relation to accurately describe both atomic and continuum limits.\nFurthermore, this approach enables analytical study at every scale. We show the\napplicability of this model in both the continuum and atomic limit by\ninvestigating modulational instability and ultrafast evolution of magnetization\ndue to transient grating, respectively, in a 1D ferromagnetic chain with\nperpendicular magnetic anisotropy. This model provides the possibility of\ngrid-independent multiscale numerical approaches that will enable the\ndescription of singularities within a single framework."
    },
    {
        "anchor": "Decoupling superconductivity and correlated insulators in twisted\n  bilayer graphene: When bilayer graphene is rotationally faulted to an angle $\\theta\\approx\n1.1^\\circ$, theory predicts the formation of a flat electronic band and\ncorrelated insulating, superconducting, and ferromagnetic states have all been\nobserved at partial band filling. The proximity of superconductivity to\ncorrelated insulators has suggested a close relationship between these states,\nreminiscent of the cuprates where superconductivity arises by doping a Mott\ninsulator. Here, we show that superconductivity can appear without correlated\ninsulating states. While both superconductivity and correlated insulating\nbehavior are strongest near the flat band condition, superconductivity survives\nto larger detuning of the angle. Our observations are consistent with a\n\"competing phases\" picture, in which insulators and superconductivity arise\nfrom disparate mechanisms.",
        "positive": "Spin-Torque-Induced Rotational Dynamics of a Magnetic Vortex Dipole: We study, both experimentally and by numerical modeling, the magnetic\ndynamics that can be excited in a magnetic thin-film nanopillar device using\nthe spin torque from a spatially localized current injected via a\n10s-of-nm-diameter aperture. The current-driven magnetic dynamics can produce\nlarge amplitude microwave emission at zero magnetic field, with a frequency\nwell below that of the uniform ferromagnetic resonance mode. Micromagnetic\nsimulations indicate that the physical origin of this efficient microwave\nnano-oscillator is the nucleation and subsequent steady-state rotational\ndynamics of a magnetic vortex dipole driven by the localized spin torque. These\nresults show this novel implementation of a spintronic nano-oscillator is a\npromising candidate for microwave technology applications."
    },
    {
        "anchor": "Stability of negative and positive trions in quantum wires: Binding energies of negative ($X^-$) and positive trions ($X^+$) in quantum\nwires are studied for strong quantum confinement of carriers which results in a\nnumerical exactly solvable model. The relative electron and hole localization\nhas a strong effect on the stability of trions. For equal hole and electron\nconfinement, $X^+$ is more stable but a small imbalance of the particle\nlocalization towards a stronger hole localization e.g. due to its larger\neffective mass, leads to the interchange of $X^-$ and $X^+$ recombination lines\nin the photoluminescent spectrum as was recently observed experimentally. In\ncase of larger $X^-$ stability, a magnetic field oriented parallel to the wire\naxis leads to a stronger increase of the $X^+$ binding energy resulting in a\ncrossing of the $X^+$ and $X^-$ lines.",
        "positive": "Observation of an anomalous density-dependent energy gap of the\n  $\u03bd=5/2$ fractional quantum Hall state in the low density regime: We have studied the $\\nu=5/2$ fractional quantum Hall state in a\ndensity-tunable sample at extremely low electron densities. For the densities\naccessed in our experiment, the Landau level mixing parameter $\\kappa$ spans\nthe $2.52<\\kappa<2.82$ range. In the vicinity of $5.8 \\times 10^{10}$~cm$^{-2}$\nor $\\kappa = 2.6$ an anomalously large change in the density dependence of the\nenergy gap is observed. Possible origins of such an anomaly are discussed,\nincluding a topological phase transition in the $\\nu=5/2$ fractional quantum\nHall state."
    },
    {
        "anchor": "Chaos based Berry phase detector: The geometric or Berry phase, a characteristic of quasiparticles, is\nfundamental to the underlying quantum materials. The discoveries of new\nmaterials at a rapid pace nowadays call for efficient detection of the Berry\nphase. Utilizing $\\alpha$-T$_3$ lattice as a paradigm, we find that, in the\nDirac electron optics regime, the semiclassical decay of the quasiparticles\nfrom a chaotic cavity can be effectively exploited for detecting the Berry\nphase. In particular, we demonstrate a one-to-one correspondence between the\nexponential decay rate and the geometric phase for the entire family of\n$\\alpha$-T$_3$ materials. This chaos based detection scheme represents an\nexperimentally feasible way to assess the Berry phase and to distinguish the\nquasiparticles.",
        "positive": "Zero-energy bound state at the interface between an $s$-wave\n  superconductor and a disordered normal metal with repulsive electron-electron\n  interactions: In recent years, there has been a renewed interest in the proximity effect\ndue to its role in the realization of topological superconductivity. Here, we\nstudy a superconductor--normal metal proximity system with repulsive\nelectron-electron interactions in the normal layer. It is known that in the\nabsence of disorder or normal reflection at the superconductor--normal metal\ninterface, a zero-energy bound state forms and is localized to the interface\n[Fauchere et al., Phys. Rev. Lett. 82, 3336 (1999)]. Using the quasiclassical\ntheory of superconductivity, we investigate the low-energy behavior of the\ndensity of states in the presence of finite disorder and an interfacial\nbarrier. We find that as the mean free path is decreased, the zero-energy peak\nin the density of states is broadened and reduced. In the quasiballistic limit,\nthe bound state eliminates the minigap pertinent to a noninteracting normal\nlayer and a distinct peak is observed. When the mean free path becomes\ncomparable to the normal layer width, the zero-energy peak is strongly\nsuppressed and the minigap begins to develop. In the diffusive limit, the\nminigap is fully restored and all signatures of the bound state are eliminated.\nWe find that an interfacial potential barrier does not change the functional\nform of the density of states peak but does shift this peak away from zero\nenergy."
    },
    {
        "anchor": "Tuning of the magnetic properties of the high spin molecular cluster Fe8: The synthesis, crystal structure and magnetic characterization of a high spin\ncluster comprising eight iron ions, are presented in this contribution. The\ncluster has formula [(tacn)6Fe8O2(OH)12Br4.3(ClO4)3.7]6H2O, (Fe8PCL) where tacn\nis the organic ligand 1,4,7-triazacyclononane. It can be considered a\nderivative of Fe8Br8, a cluster whose low temperature dynamics of the\nmagnetization has been deeply investigated, where four of the bromide ions have\nbeen replaced by perchlorate anions. The structure of the central core of the\ntwo molecules, [Fe8O(OH)12(tacn)6]8+, is essentially the same, but Fe8PCL has a\nhigher symmetry (Fe8Br8 crystallizes in the acentric P1 space group, while\nFe8PCL crystallizes in the P21/c space group, monoclinic). The magnetic\nproperties of Fe8PCL suggest it is very similar to Fe8Br having a S=10 ground\nstate as well. The zero field splitting parameters were accurately determined\nby HF-EPR measurements. The two clusters have similar axial anisotropy but\nFe8PCL has a larger transverse anisotropy. Ac susceptibility measurements\nrevealed the cluster behaves like a superparamagnetic particle. However, due to\nthe occurrence of large terms in the transverse anisotropy, the temperature\ndependence of the relaxation time can not be reproduced by a simple Arrhenius\nlaw. As observed in Fe8Br8, below 350 mK the relaxation time becomes\ntemperature independent, indicating that a pure tunneling regime is attained.\nThe comparison of the tunneling rate in the two clusters shows that in the\nperchlorate derivative the relaxation process is 35 times faster. The observed\nratio of the tunneling rates is in reasonable agreement with that calculated\nfrom the tunneling splitting, i.e. the energy difference between the two almost\ndegenerate lowest levels Ms = +/-10, in the two clusters.",
        "positive": "Evolution of Superconductivity in Twisted Graphene Multilayers: The group of moir\\'e graphene superconductors keeps growing, and by now it\ncontains twisted graphene multilayers and twisted double bilayers. We analyze\nthe contribution of long range charge fluctuations in the superconductivity of\ntwisted double graphene bilayers and helical trilayers, and compare the results\nto twisted bilayer graphene. We apply a diagrammatic approach which depends on\na few, well known parameters. We find that the critical temperature and the\norder parameter differ significantly between twisted double bilayers and\nhelical trilayers on one hand, and twisted bilayer graphene on the other. We\nshow that this trend, consistent with experiments, can be associated to the\nrole played by moir\\'e Umklapp processes in the different systems."
    },
    {
        "anchor": "Numerical Green's Function Modeling of One-Dimensional Quantum Transport: Since the initial development of one-dimensional electron gases (1DEG) two\ndecades ago, there has been intense interest in both the fundamental physics\nand the potential applications, including quantum computation, of these quantum\ntransport systems. While experimental measurements of 1DEGs reveal the\nconductance through a system, they do not probe critical other aspects of the\nunderlying physics, including energy eigenstate distribution, magnetic field\neffects, and band structure. These are better accessed by theoretical modeling,\nespecially modeling of the energy and wavefunction distribution across a\nsystem: the local density of states (DOS). In this thesis, a numerical Greens\nfunction model of the local DOS in a 1DEG has been developed and implemented.\nThe model uses an iterative method in a discrete lattice to calculate Greens\nfunctions by vertical slice across a 1DEG. The numerical model is adaptable to\narbitrary surface gate geometry and arbitrary finite magnetic field conditions.\nWhen compared with exact analytical results for the local DOS, waveband\nstructure, and real band structure, the model returned very accurate results. A\nsecond numerical model was also developed that measured the transmission and\nreflection coefficients through the quantum system based on the\nLandauer-Buttiker formalism. The combination of the local DOS model with the\ntransmission coefficients model was applied to two current research topics:\nantidot behavior and zero-dimensional to one-dimensional tunneling. These\nmodels can be further applied to investigate a wide range of quantum transport\nphenomena.",
        "positive": "Quantum Fluctuations along Symmetry Crossover in Kondo-correlated\n  Quantum Dot: Universal properties of entangled many-body states are controlled by their\nsymmetry and quantum fluctuations. By magnetic-field tuning of the spin-orbital\ndegeneracy in a Kondo-correlated quantum dot, we have modified quantum\nfluctuations to directly measure their influence on the many-body properties\nalong the crossover from $SU(4)$ to $SU(2)$ symmetry of the ground state.\nHigh-sensitive current noise measurements combined with the non-equilibrium\nFermi liquid theory clarify that the Kondo resonance and electron correlations\nare enhanced as the fluctuations, measured by the Wilson ratio, increase along\nthe symmetry crossover. Our achievement demonstrates that non-linear noise\nconstitutes a measure of quantum fluctuations that can be used to tackle\nquantum phase transitions."
    },
    {
        "anchor": "Consequences of Many-cell Correlations in Treating Clocked Quantum-dot\n  Cellular Automata Circuits: Quantum-dot Cellular Automata (QCA) provides a basis for classical\ncomputation without transistors. Many simulations of QCA rely upon the\nso-called Intercellular Hartree Approximation (ICHA), which neglects the\npossibility of entanglement between cells. Here, we present computational\nresults that treat small groups of QCA cells with a Hamiltonian analogous to a\nquantum mechanical Ising-like spin chain in a transverse field, including the\neffects of intercellular entanglement. When energy relaxation is included in\nthe model, we find that intercellular entanglement changes the qualitative\nbehaviour of the system, and new features appear. In clocked QCA, isolated\ngroups of active cells experience oscillations in their polarization states as\ninformation propagates. Additionally, energy relaxation tends to bring groups\nof cells to an unpolarized ground state. This contrasts with the results of\nprevious simulations which employed the ICHA. The ICHA is a valid approximation\nin the limit of very low tunneling rates, which can be realized in\nlithographically defined quantum-dots. However, in molecular and atomic\nimplementations of QCA, entanglement will play a greater role. The degree to\nwhich entanglement poses a problem for memory and clocking depends upon the\ninteraction of the system with its environment, as well as the system's\ninternal dynamics.",
        "positive": "Mechanisms of normal reflection at metal interfaces studied by\n  Andreev-reflection spectroscopy: Andreev-reflection spectroscopy of elemental superconductors in contact with\nnon-magnetic normal metals reveals that the strength of normal-reflection\nvaries only slightly. This observation imposes strong constrictions on the\nthree possible normal-reflection mechanisms: tunneling through a dielectric\nbarrier, reflection due to the different electronic properties of the two\nelectrodes, and diffusive transport caused by elastic scattering in the contact\nregion. We discuss in detail the role played by Fermi-surface mismatch,\nrepresented by the different Fermi velocities on both sides of the contact\ninterface. We find that it is at least not the dominant mechanism and possibly\ncompletely absent in the Andreev-reflection process."
    },
    {
        "anchor": "Validity criteria for Fermi's golden rule scattering rates applied to\n  metallic nanowires: Fermi's golden rule underpins the investigation of mobile carriers\npropagating through various solids, being a standard tool to calculate their\nscattering rates. As such, it provides a perturbative estimate under the\nimplicit assumption that the effect of the interaction Hamiltonian which causes\nthe scattering events is sufficiently small. To check the validity of this\nassumption, we present a general framework to derive simple validity criteria\nin order to assess whether the scattering rates can be trusted for the system\nunder consideration, given its statistical properties such as average size,\nelectron density, impurity density et cetera. We derive concrete validity\ncriteria for metallic nanowires with conduction electrons populating a single\nparabolic band subjected to different elastic scattering mechanisms:\nimpurities, grain boundaries and surface roughness.",
        "positive": "Unitary limit in crossed Andreev transport: One of the most promising approaches of generating spin- and energy-entangled\nelectron pairs is splitting a Cooper pair into the metal through spatially\nseparated terminals. Utilizing hybrid systems with the energy-dependent\nbarriers at the superconductor-normal metal interfaces, one can achieve\npractically 100% efficiency outcome of entangled electrons. We investigate\nminimalistic one-dimensional model comprising a superconductor and two metallic\nleads and derive an expression for an electron-to-hole transmission probability\nas a measure of splitting efficiency. We find the conditions for achieving 100%\nefficiency and present analytical results for the differential conductance and\ndifferential noise."
    },
    {
        "anchor": "Memristor: Why do we have to know about it?: Review on Memristor.",
        "positive": "Thermal transport driven by Coulomb interactions in quantum dots:\n  Enhancement of thermoelectric and heat currents: We investigate thermal transport in a serial asymmetric double quantum dot\n(DQD) coupled to two electron reservoirs with different temperatures. The\ninter- and intra-Coulomb interactions are taken into account in a Coulomb\nblockade DQD where the electron sequential tunneling via four different master\nequation approaches is considered. In the absence of Coulomb interactions, a\nneglectable thermoelectric and heat currents is found identifying as the\nCoulomb blockade DQD regime. In the presence of Coulomb interactions, intra-\nand inter-Coulomb interactions, crossings energies between the intra- and the\ninter-dot many-body electron states are observed. The crossings induce extra\nchannels in the energy spectrum of the DQD that enhance thermoelectric and heat\ncurrents. The extra channels form several peaks in the thermoelectric and heat\ncurrents in which intensity and position of the peaks depend on strength of the\ninter- and intra-dot Coulomb interactions. In addition, the problem of\ncoherences and incoherences are studied using different approaches to the\nmaster equation, which are the first order von-Neumann, the Redfield, a first\norder Lindblad, and the Pauli methods. We find that all methods give almost\nsimilar thermal transport when the role of the coherences is irrelevant in the\nDQD."
    },
    {
        "anchor": "Ghost Fano resonance in a double quantum dot molecule attached to leads: We study the electronic transport through a double quantum dot molecule\nattached to leads, and examine the transition from a configuration in series to\na symmetrical parallel geometry. We find that a progressive reduction of the\ntunneling through the antibonding state takes place as a result of the\ndestructive quantum interference between the different pathways through the\nmolecule. The Fano resonance narrows down, disappearing entirely when the\nconfiguration is totally symmetric, so that only the bonding state participates\nof the transmission. In this limit the antibonding state becomes completely\nlocalized.",
        "positive": "Anomalous Stark Shift of Excitonic Complexes in Monolayer Semiconductor: Monolayer transition metal dichalcogenide semiconductors host strongly bound\ntwo-dimensional excitonic complexes, and form an excellent platform for probing\nmany-body physics through manipulation of Coulomb interaction. Quantum confined\nStark effect is one of the routes to dynamically tune the emission line of\nthese excitonic complexes. In this work, using a high quality\ngraphene/hBN/WS$_2$/hBN/Au vertical heterojunction, we demonstrate for the\nfirst time, an out-of-plane electric field driven change in the sign of the\nStark shift from blue to red for four different excitonic species, namely, the\nneutral exciton, the charged exciton (trion), the charged biexciton, and the\ndefect-bound exciton. Such universal non-monotonic Stark shift with electric\nfield arises from a competition between the conventional quantum confined Stark\neffect driven red shift and a suppressed binding energy driven anomalous blue\nshift of the emission lines, with the latter dominating in the low field\nregime. We also find that the encapsulating environment of the monolayer TMDC\nplays an important role in wave function spreading, and hence in determining\nthe magnitude of the blue Stark shift. The results for neutral and charged\nexcitonic species are in excellent agreement with calculations from\nBethe-Salpeter Equation that uses seven-band per spin tight binding\nHamiltonian. The findings have important implications in probing many-body\ninteraction in the two dimension as well as in developing layered semiconductor\nbased tunable optoelectronic devices."
    },
    {
        "anchor": "Tailed skyrmions -- an obscure branch of magnetic solitons: We report tailed skyrmions -- a new class of stable soliton solutions of the\n2D chiral magnet model. Tailed skyrmions have elongated shapes and emerge in a\nnarrow range of fields near the transition between the spin spirals and the\nsaturated state. We analyze the stability range of these solutions in terms of\nexternal magnetic field and magnetocrystalline anisotropy. Minimum energy paths\nand the homotopies (continuous transitions) between tailed skyrmions of the\nsame topological charge have been calculated using the geodesic nudged elastic\nbands method. The discovery of tailed skyrmions extends the diversity of\nalready-known solutions illustrated by complex morphology solitons, such as\ntailed skyrmion bags with and without chiral kinks.",
        "positive": "Finite-frequency noise in a non-interacting quantum dot: We calculate the non-symmetrized finite-frequency NS-FF noise for a\nsingle-level quantum dot connected to reservoirs in the spinless\nnon-interacting case. The calculations are performed within the framework of\nthe Keldysh Green's function formalism in the wide band approximation limit. We\nestablish the general formula for NS-FF noise for any values of temperature,\nfrequency and bias voltage. The electron transfer processes from one to the\nother reservoir act via the transmission amplitude and transmission coefficient\ndepending on the energy. By taking the symmetrized version of this expression,\nwe show that our result coincides with the expression of the finite frequency\nnoise obtained by B\\\"uttiker using the scattering theory. We also give the\nexplicit analytical expression for the NS-FF noise in the zero temperature\nlimit. By performing numerical calculations, we finally discuss the evolution\nof the NS-FF noise spectrum when varying temperature, dot energy level, and\ncoupling strength to the reservoirs, revealing a large variety of behaviors\nwith different symmetry properties."
    },
    {
        "anchor": "Non-volatile rewritable frequency tuning of a nanoelectromechanical\n  resonator using photoinduced doping: Tuning the frequency of a resonant element is of vital importance in both the\nmacroscopic world, such as when tuning a musical instrument, as well as at the\nnanoscale. In particular, precisely controlling the resonance frequency of\nisolated nanoelectromechanical resonators (NEMS) has enabled innovations such\nas tunable mechanical filtering and mixing as well as commercial technologies\nsuch as robust timing oscillators. Much like their electronic device\ncounterparts, the potential of NEMS grows when they are built up into\nlarge-scale arrays. Such arrays have enabled neutral-particle mass spectroscopy\nand have been proposed for ultralow-power alternatives to traditional analog\nelectronics as well as nanomechanical information technologies like memory,\nlogic, and computing. A fundamental challenge to these applications is to\nprecisely tune the vibrational frequency and coupling of all resonators in the\narray, since traditional tuning methods, like patterned electrostatic gating or\ndielectric tuning, become intractable when devices are densely packed. Here, we\ndemonstrate a persistent, rewritable, scalable, and high-speed frequency tuning\nmethod for graphene-based NEMS. Our method uses a focused laser and two shared\nelectrical contacts to photodope individual resonators by simultaneously\napplying optical and electrostatic fields. After the fields are removed, the\ntrapped charge created by this process persists and applies a local\nelectrostatic tension to the resonators, tuning their frequencies. By providing\na facile means to locally address the strain of a NEMS resonator, this approach\nlays the groundwork for fully programmable large-scale NEMS lattices and\nnetworks.",
        "positive": "Magnetic Control of Valley Pseudospin in Monolayer WSe2: Local energy extrema of the bands in momentum space, or valleys, can endow\nelectrons in solids with pseudo-spin in addition to real spin. In transition\nmetal dichalcogenides this valley pseudo-spin, like real spin, is associated\nwith a magnetic moment which underlies the valley-dependent circular dichroism\nthat allows optical generation of valley polarization, intervalley quantum\ncoherence, and the valley Hall effect. However, magnetic manipulation of valley\npseudospin via this magnetic moment, analogous to what is possible with real\nspin, has not been shown before. Here we report observation of the valley\nZeeman splitting and magnetic tuning of polarization and coherence of the\nexcitonic valley pseudospin, by performing polarization-resolved\nmagneto-photoluminescence on monolayer WSe2. Our measurements reveal both the\natomic orbital and lattice contributions to the valley orbital magnetic moment;\ndemonstrate the deviation of the band edges in the valleys from an exact\nmassive Dirac fermion model; and reveal a striking difference between the\nmagnetic responses of neutral and charged valley excitons which is explained by\nrenormalization of the excitonic spectrum due to strong exchange interactions."
    },
    {
        "anchor": "Anisotropic Friedel oscillations inside the domain wall: The influence of the non-collinear magnetic configuration on Friedel is\ninvestigated theoretically. Specifically the influence of the magnetic\nconfiguration on the induced electric charge in a N\\'{e}el type domain wall\n(DW) has been obtained. The well-known Levy and Zhang eigenstates for a linear\nDW have been employed. Then the dielectric function of this magnetic system has\nbeen obtained within the random phase approximation. Results of the current\nwork demonstrated that magnetic configuration of the system manifests itself in\nthe electric properties such as induced charge distribution. Meanwhile the\nanisotropy of the induced charge distribution in the real space provides a\nmeasurable way for the determination of the DW orientation. In addition\nanisotropy of the dielectric function in k-space arises as a result of the\nanisotropy of the magnetic configuration. Therefore the orientation of the\nmagnetic DW could also be captured by full optical measurements.",
        "positive": "Role of interlayer spacing on electronic, thermal and optical properties\n  of BN-codoped bilayer graphene:\\break Influence of the interlayer and the\n  induced dipole-dipole interactions: We demonstrate that the electronic, thermal, and optical properties of a\ngraphene bilayer with boron and nitrogen dopant atoms can be controlled by the\ninterlayer distance between the layers in which the interaction energy and the\nvan der Waals interaction between the dopant atoms play an essential role. We\nfind a conversion of an AA- to an AB-stacked bilayer graphene caused by the\nrepulsive interaction between dopant atoms. At a short interlayer distance, a\nstrong repulsive interaction inducing a strong electric dipole moment of the\ndopant atoms is found. This gives rise to a breaking of the high symmetry,\nopening up a bandgap. Consequently, a considerable change in thermoelectric\nproperties such as the Seebeck coefficient and the figure of merit are seen.\nThe repulsive interaction is reduced by increasing the interlayer distance, and\nat a large interlayer distance the conversion process of the stacking order\nvanishes. A small bandgap is found leading to a low Seebeck coefficient and a\nfigure of merit. For both short and large interlayer distances, a prominent\npeak in the optical response is found in the visible range and the peak\nposition is inversely proportional to the interlayer distance."
    },
    {
        "anchor": "Surface Chern-Simons theory for third-order topological insulators and\n  superconductors: Three-dimensional 3rd-order topological insulators (TOTIs) and\nsuperconductors (TOTSCs), as the highestorder topological phases hosting zero\ncorner modes in physical dimension, has sparked extensive research interest.\nHowever, such topological states have not been discovered in reality due to the\nlack of experimental schemes of realization. Here, we propose a novel surface\nChern-Simons (CS) theory for 3rd-order topological phases, and show that the\ntheory enables a feasible and systematic design of TOTIs and TOTSCs. We show\nthat the emergence of zero Dirac (Majorana) corner modes is entirely captured\nby an emergent $\\mathbb{Z}_{2}$ CS term that can be further characterized by a\nnovel two-particle Wess-Zumino (WZ) term uncovered here in the surfaces of\nthree-dimensional topological materials. Importantly, our proposed CS term\ncharacterization and two-particle WZ term mechanism provide a unique\nperspective to design TOTIs (TOTSCs) in terms of minimal ingredients, feasibly\nguiding the search for underlying materials, with promising candidates being\ndiscussed. This work shall advance both the theoretical and experimental\nresearch for highest-order topological matters.",
        "positive": "Superconductivity and strong interactions in a tunable moir\u00e9\n  quasiperiodic crystal: Electronic states in quasiperiodic crystals generally preclude a Bloch\ndescription, rendering them simultaneously fascinating and enigmatic. Owing to\ntheir complexity and relative scarcity, quasiperiodic crystals are\nunderexplored relative to periodic and amorphous structures. Here, we introduce\na new type of highly tunable quasiperiodic crystal easily assembled from\nperiodic components. By twisting three layers of graphene with two different\ntwist angles, we form two moir\\'e patterns with incommensurate moir\\'e unit\ncells. In contrast to many common quasiperiodic structures that are defined on\nthe atomic scale, the quasiperiodicity in our system is defined on moir\\'e\nlength scales of several nanometers. This novel \"moir\\'e quasiperiodic crystal\"\nallows us to tune the chemical potential and thus the electronic system between\na periodic-like regime at low energies and a strongly quasiperiodic regime at\nhigher energies, the latter hosting a large density of weakly dispersing\nstates. Interestingly, in the quasiperiodic regime we observe superconductivity\nnear a flavor-symmetry-breaking phase transition, the latter indicative of the\nimportant role electronic interactions play in that regime. The prevalence of\ninteracting phenomena in future systems with in situ tunability is not only\nuseful for the study of quasiperiodic systems, but it may also provide insights\ninto electronic ordering in related periodic moir\\'e crystals. We anticipate\nthat extending this new platform to engineer quasiperiodic crystals by varying\nthe number of layers and twist angles, and by using different two-dimensional\ncomponents, will lead to a new family of quantum materials to investigate the\nproperties of strongly interacting quasiperiodic crystals."
    },
    {
        "anchor": "Controllable valley splitting in silicon quantum devices: Silicon has many attractive properties for quantum computing, and the quantum\ndot architecture is appealing because of its controllability and scalability.\nHowever, the multiple valleys in the silicon conduction band are potentially a\nserious source of decoherence for spin-based quantum dot qubits. Only when\nthese valleys are split by a large energy does one obtain well-defined and\nlong-lived spin states appropriate for quantum computing. Here we show that the\nsmall valley splittings observed in previous experiments on Si/SiGe\nheterostructures result from atomic steps at the quantum well interface.\nLateral confinement in a quantum point contact limits the electron\nwavefunctions to several steps, and enhances the valley splitting\nsubstantially, up to 1.5 meV. The combination of electronic and magnetic\nconfinement produces a valley splitting larger than the spin splitting, which\nis controllable over a wide range. These results improve the outlook for\nrealizing spin qubits with long coherence times in silicon-based devices.",
        "positive": "A Novel Non-Fermi Liquid Ground State in One Dimension: We propose a new non-Fermi liquid ground state in one dimension that is not\nof the Luttinger type. It is the ground state of fermions interacting via a\nlong range repulsive interaction in real space of the form $ V(x) = e^2/|x| $.\nWe characterise it by computing the momentum distribution which is perfectly\nflat near the Fermi points signalling a radical departure from Luttinger liquid\ntheory(and Fermi liquid theory). The dispersion of elementary excitations is\nfound to be sublinear but gapless of the form $ v {} |q| {}[ Log[2k_{F}/|q|\n]^{{1/2}} $. We also compute the conductance of a mesoscopic wire made of such\nobjects and contrast it from the answer we obtain for a Luttinger wire."
    },
    {
        "anchor": "Magnetoconductance switching in an array of oval quantum dots: Employing oval shaped quantum billiards connected by quantum wires as the\nbuilding blocks of a linear quantum dot array, we calculate the ballistic\nmagnetoconductance in the linear response regime. Optimizing the geometry of\nthe billiards, we aim at a maximal finite- over zero-field ratio of the\nmagnetoconductance. This switching effect arises from a relative phase change\nof scattering states in the oval quantum dot through the applied magnetic\nfield, which lifts a suppression of the transmission characteristic for a\ncertain range of geometry parameters. It is shown that a sustainable switching\nratio is reached for a very low field strength, which is multiplied by\nconnecting only a second dot to the single one. The impact of disorder is\naddressed in the form of remote impurity scattering, which poses a temperature\ndependent lower bound for the switching ratio, showing that this effect should\nbe readily observable in experiments.",
        "positive": "Partial lattice defects in higher order topological insulators: Nonzero weak topological indices are thought to be a necessary condition to\nbind a single helical mode to lattice dislocations. In this work we show that\nhigher-order topological insulators (HOTIs) can, in fact, host a single helical\nmode along screw or edge dislocations (including step edges) in the absence of\nweak topological indices. When this occurs, the helical mode is necessarily\nbound to a dislocation characterized by a fractional Burgers vector,\nmacroscopically detected by the existence of a stacking fault. The robustness\nof a helical mode on a partial defect is demonstrated by an adiabatic\ntransformation that restores translation symmetry in the stacking fault. We\npresent two examples of HOTIs, one intrinsic and one extrinsic, that show\nhelical modes at partial dislocations. Since partial defects and stacking\nfaults are commonplace in bulk crystals, the existence of such helical modes\ncan measurably affect the expected conductivity in these materials."
    },
    {
        "anchor": "Theory of measuring the \"Luttinger-g\" of a one-dimensional quantum dot: We study electron transport through a quantum dot in a Tomonaga-Luttinger\nliquid with an inhomogeneity induced either by a non-uniform electron\ninteraction or by the presence of tunnel resistances of contacts. The\nnon-analytic temperature behavior of the conductance peaks show crossovers\ndetermined by the different energy scales associated with the dot and the\ninhomogeneity despite the Coulomb blockade remains intact. This suggests an\nexplanation of recent findings in semiconductor quantum wires and carbon\nnanotubes.",
        "positive": "Energy Transfer Controlled by Dynamical Stark Shift in Two-level\n  Dissipative Systems: A strong electromagnetic field interacting with an electron system generates\nboth the Rabi oscillations and the Stark splitting of the electron density.\nChanging of the electron density gives rise to nonadiabatic effects due to\nexistence of the electron-vibrational interaction in a dissipative system. In\nthis Letter, the mechanism of energy transfer between the electron system and\nthe phonon reservoir is presented. This mechanism is based on establishment of\nthe coupling between the electron states dressed by the electromagnetic field\nand the forced vibrations of reservoir oscillators under the action of rapid\nchanging of the electron density with the Rabi frequency. The photoinduced\nvibronic coupling results in appearance of the states that are doubly dressed\nby interaction, first time due to the electron-photon interaction, and second\ntime due to the electron-vibrational interaction. Moreover, this coupling opens\nthe way to control energy which can be transferred to (heating) or removed from\n(cooling) the phonon reservoir depending on the parameters of the\nelectromagnetic pulse."
    },
    {
        "anchor": "Quasiparticle self-energy and many-body effective mass enhancement in a\n  two-dimensional electron liquid: Motivated by a number of recent experimental studies we have revisited the\nproblem of the microscopic calculation of the quasiparticle self-energy and\nmany-body effective mass enhancement in a two-dimensional electron liquid. Our\nsystematic study is based on the many-body local fields theory and takes\nadvantage of the results of the most recent Diffusion Monte Carlo calculations\nof the static charge and spin response of the electron liquid. We report\nextensive calculations of both the real and imaginary parts of the\nquasiparticle self-energy. We also present results for the many-body effective\nmass enhancement and the renormalization constant over an extensive range of\nelectron density. In this respect we critically examine the relative merits of\nthe on-shell approximation versus the self-consistent solution of the Dyson\nequation. We show that in the strongly-correlated regime a solution of the\nDyson equation proves necessary in order to obtain a well behaved effective\nmass. The inclusion of both charge- and spin-density fluctuations beyond the\nRandom Phase Approximation is indeed crucial to get reasonable agreement with\nrecent measurements.",
        "positive": "Probing the Hydrogen Enhanced Near-Field Emission of ITO without a\n  Vacuum-Gap: Thermal fluctuations of charged particles, fluctuations akin to Brownian\nmotion, can excite optical surface-states leading to the concept of the thermal\nnear-field, which is a highly localized, and, therefore, evanescent optical\ndensity of states that exist at distances much less than the thermal emission\nwavelength. By tunneling the surface charge emitted photons into nearby\nwaveguides, the thermally excitable near-field optical density of states can be\nenhanced, engineered, and efficiently extracted to the far-field for\nobservation. With this technique, the plasmonic thermal near-field of a 10nm\nthick ITO film, known to have plasmonic activity in the 1500nm wavelength\nregion, was probed under external illumination and by thermal excitation at\n873K. The results confirm that waveguides provide a large density of optical\nchannels with spatial overlap and k-vector matching to facilitate plasmon\nde-excitation in the near-field through photon tunneling for extraction into\nthe far-field. Furthermore, it is shown that the thermal near-field can be\nobserved without the introduction of a vacuum-gap, a feature unique to this\nparticular method."
    },
    {
        "anchor": "Non-collinear spin states in bottom-up fabricated atomic chains: Non-collinear spin states with unique rotational sense, such as chiral\nspin-spirals, are recently heavily investigated because of advantages for\nfuture applications in spintronics and information technology and as potential\nhosts for Majorana Fermions when coupled to a superconductor. Tuning the\nproperties of such spin states, e.g., the rotational period and sense, is a\nhighly desirable yet difficult task. Here, we experimentally demonstrate the\nbottom-up assembly of a spin-spiral derived from a chain of Fe atoms on a Pt\nsubstrate using the magnetic tip of a scanning tunneling microscope as a tool.\nWe show that the spin-spiral is induced by the interplay of the Heisenberg and\nDzyaloshinskii-Moriya components of the Ruderman-Kittel-Kasuya-Yosida\ninteraction between the Fe atoms. The relative strengths and signs of these two\ncomponents can be adjusted by the interatomic Fe distance, which enables\ntailoring of the rotational period and sense of the spin-spiral.",
        "positive": "Thermal stability of cubane C8H8: The reasons for the anomalously high thermal stability of cubane C8H8 and the\nmechanisms of its decomposition are studied by numerically simulating the\ndynamics of this metastable cluster at T = 1050 - 2000 K using a tight-binding\npotential. The decomposition activation energy is found from the temperature\ndependence of the cubane lifetime obtained from the numerical experiment; this\nenergy is fairly high, Ea = 1.8 - 2.0 eV. The decomposition products are, as a\nrule, either C6H6 and C2H2 molecules or the isomer C8H8 with a lower energy."
    },
    {
        "anchor": "A single-particle path integral for composite fermions and the\n  renormalization of the effective mass: To study composite fermions around an even denominator fraction, we adapt the\nphase space single-particle path integral technique for interacting electrons\nin zero magnetic field developed recently by D.S. Golubev and A.D. Zaikin,\nPhys. Rev. B {\\bf 59}, 9195 (1999). This path integral description gives an\nintuitive picture of composite fermion propagation very similar to the\nCaldeira-Leggett treatment of a particle interacting with an external\nenvironment. We use the new description to explain the origin of the famous\ncancellation between the self-energy and the vertex corrections in\nsemi-classical transport measurements. The effective range of the cancellation\nis given by the size of the propagating particle, which for the Coulomb\ninteraction scales with the temperature T as T^{-1/4} |log T|^{-1} in the\nsemi-classical limit. Using this scheme we find that the effective mass in the\nsemi-classical limit for composite fermions in GaAs is approximately 6 times\nthe bare mass.",
        "positive": "Trion ladder diagrams: We first derive a new ``commutation technique'' for an exciton interacting\nwith electrons, inspired from the one we recently developed for excitons\ninteracting with excitons. These techniques allow to take \\emph{exactly} into\naccount the possible exchanges between carriers. We use it to get the\n$\\mathrm{X}^-$ trion creation operator in terms of exciton and free-electron\ncreation operators. In a last part we generate the ladder diagrams associated\nto these trions. Although similar to the exciton ladder diagrams, with the hole\nreplaced by an exciton, they are actually much more tricky : (i) Due to the\ncomposite nature of the exciton, one cannot identify an exciton-electron\npotential similar to the Coulomb potential between electron and hole ; (ii) the\nspins are unimportant for excitons while they are crucial for trions, singlet\nand triplet states having different energies."
    },
    {
        "anchor": "Prospects of Zero Schottky Barrier Height in a Graphene Inserted\n  MoS2-Metal Interface: A low Schottky barrier height (SBH) at source/drain contact is essential for\nachieving high drive current in atomic layer MoS2 channel based field-effect\ntransistors. Approaches such as choosing metals with appropriate work functions\nand chemical doping are employed previously to improve the carrier injection\nfrom the contact electrodes to the channel and to mitigates the SBH between the\nMoS2 and metal. Recent experiments demonstrate significant SBH reduction when\ngraphene layer is inserted between metal slab (Ti and Ni) and MoS2. However,\nthe physical or chemical origin of this phenomenon is not yet clearly\nunderstood. In this work, density functional theory (DFT) simulations are\nperformed, employing pseudopotentials with very high basis sets to get insights\nof the charge transfer between metal and monolayer MoS2 through the inserted\ngraphene layer. Our atomistic simulations on 16 different interfaces involving\nfive different metals (Ti, Ag, Ru, Au and Pt) reveal that: (i) such a decrease\nin SBH is not consistent among various metals, rather an increase in SBH is\nobserved in case of Au and Pt (ii) unlike MoS2-metal interface, the projected\ndispersion of MoS2 remains preserved in any MoS2-graphene-metal system with\nshift in the bands on the energy axis. (iii) a proper choice of metal (e.g.,\nRu) may exhibit ohmic nature in a graphene inserted MoS2-metal contact. These\nunderstandings would provide a direction in developing high performance\ntransistors involving hetero atomic layers as contact electrodes.",
        "positive": "Quasi-low-dimensional electron gas with one populated band as a testing\n  ground for time-dependent density-functional theory: We find the analytical solution to the time-dependent density-functional\ntheory (TDDFT) problem for the quasi-low-dimensional (2D and 1D) electron gas\n(QLDEG) with only one band filled in the direction perpendicular to the system\nextent. The theory is developed at the level of TD exact exchange and yields\nthe exchange potential as an explicit nonlocal operator of the spin-density.\nThe dressed interband (image states) excitation spectra of the Q2DEG are\ncalculated, while the comparison with the Kohn-Sham (KS) transitions provides\nthe insight into the qualitative and quantitative role of the many-body\ninteractions. Important cancellations between the Hartree $f_H$ and the\nexchange $f_x$ kernels are found in the low-density limit, shedding light on\nthe interrelations between the KS and many-body excitations."
    },
    {
        "anchor": "Semiconducting Carbon Nanotubes in Photovoltaic Blends: the case of\n  PTB7:PC60BM:(6,5) SWNT: Blends of carbon nanotubes with conjugated polymer and fullerene derivatives\nare complex nanocomposite systems, which have recently attracted a great\nresearch interest for their photovoltaic ability. Therefore, gaining a better\nunderstanding of the excitonic dynamics in such materials can be important to\nboost the efficiency of excitonic solar cells. Here, we studied the\nphotophysics of a ternary system in which the polymer PTB7 and the fullerene\nderivative PCBM are integrated with (6,5) SWNTs. We highlight the contribution\nof SWNTs in the exciton dissociation and in the charge transfer process. These\nfindings can be useful for the exploitation of these multi-component systems\nfor organic photovoltaic and, in general, optoelectronic applications.",
        "positive": "Nanoscale mapping and spectroscopy of non-radiative hyperbolic modes in\n  hexagonal boron nitride nanostructures: The inherent crystal anisotropy of hexagonal boron nitride (hBN) sustains\nnaturally hyperbolic phonon polaritons, i.e. polaritons that can propagate with\nvery large wavevectors within the material volume, thereby enabling optical\nconfinement to exceedingly small dimensions. Indeed, previous research has\nshown that nanometer-scale truncated nanocone hBN cavities, with deep\nsubwavelength dimensions, support three-dimensionally confined optical modes in\nthe mid-infrared. Due to optical selection rules, only a few of many such modes\npredicted theoretically have been observed experimentally via far-field\nreflection and scattering-type scanning near-field optical microscopy. The\nPhotothermal induced resonance (PTIR) technique probes optical and vibrational\nresonances overcoming weak far-field emission by leveraging an atomic force\nmicroscope (AFM) probe to transduce local sample expansion due to light\nabsorption. Here we show that PTIR enables the direct observation of previously\nunobserved, dark hyperbolic modes of hBN nanostructures. Leveraging these\noptical modes could yield a new degree of control over the electromagnetic\nnear-field concentration, polarization and angular momentum in nanophotonic\napplications."
    },
    {
        "anchor": "Theoretical studies of electronic transport in mono- and bi-layer\n  phosphorene: A critical overview: Recent $\\textit{ab initio}$ theoretical calculations of the electrical\nperformance of several two-dimensional materials predict a low-field carrier\nmobility that spans several orders of magnitude (from 26,000 to 35 cm$^{2}$\nV$^{-1}$ s$^{-1}$, for example, for the hole mobility in monolayer phosphorene)\ndepending on the physical approximations used. Given this state of uncertainty,\nwe review critically the physical models employed, considering phosphorene, a\ngroup V material, as a specific example. We argue that the use of the most\naccurate models results in a calculated performance that is at the\ndisappointing lower-end of the predicted range. We also employ first-principles\nmethods to study high-field transport characteristics in mono- and bi-layer\nphosphorene. For thin multi-layer phosphorene we confirm the most disappointing\nresults, with a strongly anisotropic carrier mobility that does not exceed\n$\\sim$ 30 cm$^{2}$ V$^{-1}$ s$^{-1}$ at 300 K for electrons along the armchair\ndirection.",
        "positive": "Unraveling current-induced dissociation mechanisms in single-molecule\n  junctions: Understanding current-induced bond rupture in single-molecule junctions is\nboth of fundamental interest and a prerequisite for the design of molecular\njunctions, which are stable at higher bias voltages. In this work, we use a\nfully quantum mechanical method based on the hierarchical quantum master\nequation approach to analyze the dissociation mechanisms in molecular\njunctions. Considering a wide range of transport regimes, from off-resonant to\nresonant, non-adiabatic to adiabatic transport, and weak to strong vibronic\ncoupling, our systematic study identifies three dissociation mechanisms. In the\nweak and intermediate vibronic coupling regime, the dominant dissociation\nmechanism is stepwise vibrational ladder climbing. For strong vibronic\ncoupling, dissociation is induced via multi-quantum vibrational excitations\ntriggered either by a single electronic transition at high bias voltages or by\nmultiple electronic transitions at low biases. Furthermore, the influence of\nvibrational relaxation on the dissociation dynamics is analyzed and strategies\nfor improving the stability of molecular junctions are discussed."
    },
    {
        "anchor": "Witnessing quantum correlations in a nuclear ensemble via an electron\n  spin qubit: A coherent ensemble of spins interfaced with a proxy qubit is an attractive\nplatform to create many-body coherences and probe the regime of collective\nexcitations. An electron spin qubit in a semiconductor quantum dot can act as\nsuch an interface to the dense nuclear spin ensemble within the quantum dot\nconsisting of multiple high-spin atomic species. Earlier work has shown that\nthe electron can relay properties of its nuclear environment through the\nstatistics of its mean-field interaction with the total nuclear polarisation,\nnamely its mean and variance. Here, we demonstrate a method to probe the spin\nstate of a nuclear ensemble that exploits its response to collective spin\nexcitations, enabling a species-selective reconstruction beyond the mean field.\nFor the accessible range of optically prepared mean fields, the reconstructed\npopulations indicate that the ensemble is in a non-thermal, correlated nuclear\nstate. The sum over reconstructed species-resolved polarisations exceeds the\nclassical prediction threefold. This stark deviation follows from a spin\nensemble that contains inter-particle coherences, and serves as an entanglement\nwitness that confirms the formation of a dark many-body state.",
        "positive": "Chiral anomaly as origin of planar Hall effect in Weyl semimetals: In condensed matter physics, the term \"chiral anomaly\" implies the violation\nof the separate number conservation laws of Weyl fermions of different\nchiralities in the presence of parallel electric and magnetic fields. One\neffect of chiral anomaly in the recently discovered Dirac and Weyl semimetals\nis a positive longitudinal magnetoconductance (LMC). Here we show that chiral\nanomaly and non-trivial Berry curvature effects engender another striking\neffect in WSMs, the planar Hall effect (PHE). Remarkably, PHE manifests itself\nwhen the applied current, magnetic field, and the induced transverse \"Hall\"\nvoltage all lie in the same plane, precisely in a configuration in which the\nconventional Hall effect vanishes. In this work we treat PHE quasi-classically,\nand predict specific experimental signatures for type-I and type-II Weyl\nsemimetals that can be directly checked in experiments."
    },
    {
        "anchor": "Interlayer exciton dynamics in van der Waals heterostructures: Exciton binding energies of hundreds of meV and strong light absorption in\nthe optical frequency range make transition metal dichalcogenides (TMDs)\npromising for novel optoelectronic nanodevices. In particular, atomically thin\nTMDs can be stacked to heterostructures enabling the design of new materials\nwith tailored properties. The strong Coulomb interaction gives rise to\ninterlayer excitons, where electrons and holes are spatially separated in\ndifferent layers. In this work, we reveal the microscopic processes behind the\nformation, thermalization and decay of these fundamentally interesting and\ntechnologically relevant interlayer excitonic states. In particular, we present\nfor the exemplary MoSe$_2$-WSe$_2$ heterostructure the interlayer exciton\nbinding energies and wave functions as well as their time- and energy-resolved\ndynamics. Finally, we predict the dominant contribution of interlayer excitons\nto the photoluminescence of these materials.",
        "positive": "Cavity magnonics with domain walls in insulating ferromagnetic wires: Magnetic domain walls (DWs) are topological defects that exhibit robust\nlow-energy modes that can be harnessed for classical and neuromorphic\ncomputing. However, the quantum nature of these modes has been elusive thus\nfar. Using the language of cavity optomechanics, we show how to exploit a\ngeometric Berry-phase interaction between the localized DWs and the extended\nmagnons in short ferromagnetic insulating wires to efficiently cool the DW to\nits quantum ground state or to prepare nonclassical states exhibiting a\nnegative Wigner function that can be extracted from the power spectrum of the\nemitted magnons. Moreover, we demonstrate that magnons can mediate long-range\nentangling interactions between qubits stored in distant DWs, which could\nfacilitate the implementation of a universal set of quantum gates. Our proposal\nrelies only on the intrinsic degrees of freedom of the ferromagnet, and can be\nnaturally extended to explore the quantum dynamics of DWs in ferrimagnets and\nantiferromagnets, as well as quantum vortices or skyrmions confined in\ninsulating magnetic nanodisks."
    },
    {
        "anchor": "Periodic Chaotic Billiards: Quantum-Classical Correspondence in Energy\n  Space: We investigate the properties of eigenstates and local density of states\n(LDOS) for a periodic 2D rippled billiard, focusing on their quantum-classical\ncorrespondence in energy representation. To construct the classical\ncounterparts of LDOS and the structure of eigenstates (SES), the effects of the\nboundary are first incorporated (via a canonical transformation) into an\neffective potential, rendering the one-particle motion in the 2D rippled\nbilliard equivalent to that of two-interacting particles in 1D geometry. We\nshow that classical counterparts of SES and LDOS in the case of strong chaotic\nmotion reveal quite a good correspondence with the quantum quantities. We also\nshow that the main features of the SES and LDOS can be explained in terms of\nthe underlying classical dynamics, in particular of certain periodic orbits. On\nthe other hand, statistical properties of eigenstates and LDOS turn out to be\ndifferent from those prescribed by random matrix theory. We discuss the quantum\neffects responsible for the non-ergodic character of the eigenstates and\nindividual LDOS that seem to be generic for this type of billiards with a large\nnumber of transverse channels.",
        "positive": "Non--Equilibrium Transport in Open Quantum Systems via Dynamically\n  Constrained non--Hermitian Boundary Domains: The accurate simulation of real--time quantum transport is notoriously\ndifficult, requiring a consistent scheme to treat incoming and outgoing fluxes\nat the boundary of an open system. We demonstrate a method to converge\nnon--equilibrium steady states using non--Hermitian source and sink potentials\nalongside the application of dynamic density constraints during wavefunction\npropagation. This scheme adds negligible cost to existing computational methods\nwhile exhibiting exceptional stability and numerical accuracy."
    },
    {
        "anchor": "Topological insulators in three dimensions from spontaneous symmetry\n  breaking: We study three dimensional systems where strong repulsion leads to an\ninsulating state via spontaneously generated spin-orbit interactions. We\ndiscuss a microscopic model where the resulting state is topological. Such\ntopological `Mott' insulators differ from their band insulator counterparts in\nthat they possess an additional order parameter, a rotation matrix, that\ndescribes the spontaneous breaking of spin-rotation symmetry. We show that line\ndefects of this order are associated with protected one dimensional modes in\nthe {\\em strong} topological Mott insulator, which provides a bulk\ncharacterization of this phase.",
        "positive": "Anomalous Enhancement of the Boltzmann Conductivity in Disordered Zigzag\n  Graphene Nanoribbons: We study the conductivity of disordered zigzag graphene nanoribbons in the\nincoherent regime by using the Boltzmann equation approach. The band structure\nof zigzag nanoribbons contains two energy valleys, and each valley has an\nexcess one-way channel. The crucial point is that the numbers of conducting\nchannels for two propagating directions are imbalanced in each valley due to\nthe presence of an excess one-way channel. It was pointed out that as a\nconsequence of this imbalance, a perfectly conducting channel is stabilized in\nthe coherent regime if intervalley scattering is absent. We show that even in\nthe incoherent regime, the conductivity is anomalously enhanced if intervalley\nscattering is very weak. Particularly, in the limit of no intervalley\nscattering, the dimensionless conductance approaches to unity with increasing\nribbon length as if there exists a perfectly conducting channel. We also show\nthat anomalous valley polarization of electron density appears in the presence\nof an electric field."
    },
    {
        "anchor": "Current driven spin-orbit torque oscillator: ferromagnetic and\n  antiferromagnetic coupling: We consider theoretically the impact of Rashba spin-orbit coupling on spin\ntorque oscillators (STOs) in synthetic ferromagnets and antiferromagnets that\nhave either a bulk multilayer or a thin film structure. The synthetic magnets\nconsist of a fixed polarizing layer and two free magnetic layers that interact\nthrough the Ruderman-Kittel-Kasuya-Yosida interaction. We determine\nanalytically which collinear states along the easy axis that are stable, and\nestablish numerically the phase diagram for when the system is in the STO mode\nand when collinear configurations are stable, respectively. It is found that\nthe Rashba spin-orbit coupling can induce anti-damping in the vicinity of the\ncollinear states, which assists the spin transfer torque in generating\nself-sustained oscillations, and that it can substantially increase the STO\npart of the phase diagram. Moreover, we find that the STO phase can extend deep\ninto the antiferromagnetic regime in the presence of spin-orbit torques.",
        "positive": "Intrinsic lifetime of Dirac plasmons in graphene: Dirac plasmons in a doped graphene sheet have recently been shown to enable\nconfinement of light to ultrasmall volumes. In this work we calculate the\nintrinsic lifetime of a Dirac plasmon in a doped graphene sheet by analyzing\nthe role of electron-electron interactions beyond the random phase\napproximation. The damping mechanism at work is intrinsic since it operates\nalso in disorder-free samples and in the absence of lattice vibrations. We\ndemonstrate that graphene's sublattice-pseudospin degree of freedom suppresses\nintrinsic plasmon losses with respect to those that occur in ordinary\ntwo-dimensional electron liquids. We relate our findings to a microscopic\ncalculation of the homogeneous dynamical conductivity at energies below the\nsingle-particle absorption threshold."
    },
    {
        "anchor": "Snowflake Topological Insulator for Sound Waves: We show how the snowflake phononic crystal structure, which has been realized\nexperimentally recently, can be turned into a topological insulator for sound\nwaves. This idea, based purely on simple geometrical modifications, could be\nreadily implemented on the nanoscale.",
        "positive": "A polarizing situation: Taking an in-plane perspective for\n  next-generation near-field studies: This mini-review provides a perspective on recent progress and emerging\ndirections aimed at utilizing and controlling in-plane optical polarization,\nhighlighting key application spaces where in-plane near-field tip responses\nhave enabled recent advancements in the understanding and development of new\nnanostructured materials and devices."
    },
    {
        "anchor": "Electromagnetic modes and resonances of two-dimensional bodies: The electromagnetic modes and the resonances of homogeneous, finite size,\ntwo-dimensional bodies are examined in the frequency domain by a rigorous full\nwave approach based on an integro-differential formulation of the\nelectromagnetic scattering problem. Using a modal expansion for the current\ndensity that disentangles the geometric and material properties of the body the\nintegro-differential equation for the induced surface (free or polarization)\ncurrent density field is solved. The current modes and the corresponding\nresonant values of the surface conductivity (eigen-conductivities) are\nevaluated by solving a linear eigenvalue problem with a non-Hermitian operator.\nThey are inherent properties of the body geometry and do not depend on the body\nmaterial. The material only determines the coefficients of the modal expansion\nand hence the frequencies at which their amplitudes are maximum (resonance\nfrequencies). The eigen-conductivities and the current modes are studied in\ndetail as the frequency, the shape and the size of the body vary. Open and\nclosed surfaces are considered. The presence of vortex current modes, in\naddition to the source-sink current modes (no whirling modes), which\ncharacterize plasmonic oscillations, is shown. Important topological features\nof the current modes, such as the number of sources and sinks, the number of\nvortexes, the direction of the vortexes are preserved as the size of the body\nand the frequency vary. Unlike the source-sink current modes, in open surfaces\nthe vortex current modes can be resonantly excited only in materials with\npositive imaginary part of the surface conductivity. Eventually, as examples,\nthe scattering by two-dimensional bodies with either positive or negative\nimaginary part of the surface conductivity is analyzed and the contributions of\nthe different modes are examined.",
        "positive": "Fractional charges on an integer quantum Hall edge: We propose ways to create and detect fractionally charged excitations in\n\\emph{integer} quantum Hall edge states. The charge fractionalization occurs\ndue to the Coulomb interaction between electrons propagating on different edge\nchannels. The fractional charge of the soliton-like collective excitations can\nbe observed in time resolved or frequency dependent shot noise measurements."
    },
    {
        "anchor": "Quantum nonlinear planar Hall effect in bilayer graphene: an orbital\n  effect of a steady in-plane magnetic field: We study the quantum nonlinear planar Hall effect in bilayer graphene under a\nsteady in-plane magnetic field. When time-reversal symmetry is broken by the\nmagnetic field, a charge current occurs in the second-order response to an\nexternal electric field, as a result of the Berry curvature dipole in momentum\nspace. We have shown that a nonlinear planar Hall effect originating from the\nanomalous velocity is deduced by an orbital effect of an in-plane magnetic\nfield on electrons in bilayer graphene in the complete absence of spin-orbit\ncoupling. Taking into account the symmetry analysis, we derived the dominant\ndependence of Berry curvature dipole moment on the magnetic field components.\nMoreover, we illustrate how to control and modulate the Berry curvature dipole\nwith an external planar magnetic field, gate voltage, and Fermi energy.",
        "positive": "Charge Separation and Dissipation in Molecular Wires under a Light\n  Radiation: Photo-induced charge separation in nanowires or molecular wires had been\nstudied in previous experiments and simulations. Most researches deal with the\ncarrier diffusions with the classical phenomenological models, or the static\nenergy levels by quantum mechanics calculations. Here we give a dynamic quantum\ninvestigation on the charge separation and dissipation in molecule wires. The\nmethod is based on the time-dependent non-equilibrium Green's function theory.\nPolyacetylene chain and poly-phenylene are used as model systems with a\ntight-binding Hamiltonian and the wide band limit approximation in this study.\nA light pulse with the energy larger than the band gap is radiated on the\nsystem. The evolution and dissipation of the non-equilibrium carriers in the\nopen nano systems are studied. With an external electric potentials or impurity\natoms, the charge separation is observed. Our calculations show that the\nseparation behaviors of the electron/hole wave packets are related to the\nCoulomb interaction, light intensity and the effective masses of electron/hole\nin the molecular wire."
    },
    {
        "anchor": "Theory of Half-Integer Fractional Quantum Spin Hall Insulator Edges: We study the edges of fractional quantum spin Hall insulators (FQSH) with\nhalf-integer spin Hall conductance. These states can be viewed as symmetric\ncombinations of a spin-up and spin-down half-integer fractional quantum Hall\nstate (FQH) that are time-reversal invariant, and conserve the z-component of\nspin. We consider the non-Abelian states based on the Pfaffian, anti-Pfaffian,\nPH-Pfaffian, and 221 FQH, and generic Abelian FQH. For strong enough\nspin-conserving interactions, we find that all the non-Abelian and Abelian\nedges flow to the same fixed point that consists of a single pair of charged\ncounter-propagating bosonic modes. If spin-conservation is broken, the Abelian\nedge can be fully gapped in a time-reversal symmetric fashion. The non-Abelian\nedge with broken spin-conservation remains gapless due to time-reversal\nsymmetry, and can flow to a new fixed point with a helical gapless pair of\nMajorana fermions. We discuss the possible relevance of our results to the\nrecent observation of a half-integer edge conductance in twisted MoTe2.",
        "positive": "High-field noise in metallic diffusive conductors: We analyze high-field current fluctuations in degenerate conductors by\nmapping the electronic Fermi-liquid correlations at equilibrium to their\nsemiclassical non-equilibrium form. Our resulting Boltzmann description is\napplicable to diffusive mesoscopic wires. We derive a non-equilibrium\nconnection between thermal fluctuations of the current and resistive\ndissipation. In the weak-field limit this is the canonical fluctuation-\ndissipation theorem. Away from equilibrium, the connection enables explicit\ncalculation of the excess ``hot-electron'' contribution to the thermal\nspectrum. We show that excess thermal noise is strongly inhibited by Pauli\nexclusion. This behaviour is generic to the semiclassical metallic regime."
    },
    {
        "anchor": "Suppression of electron spin decoherence in Rabi oscillations induced by\n  an inhomogeneous microwave field: The decay of Rabi oscillations provides direct information about coherence of\nelectron spins. When observed in EPR experiments, it is often shortened by\nspatial inhomogeneity of the microwave field amplitude in a bulk sample. In\norder to suppress this undesired loss of coherence, we propose an additional\ndressing of spin states by a weak longitudinal continuous radiofrequency field.\nOur calculations of the Rabi oscillations between the doubly dressed spin\nstates show that the maximum suppression of decoherence is achieved at the\nso-called Rabi resonance when the radio-field frequency is in resonance with\nthe Rabi frequency of spins in the microwave field. This effect is feasible\neven in the absence of phase matching in the radiofrequency field and for\ndifferent types of inhomogeneity of the microwave field. The manifestations of\nsuch suppression in the published EPR experiments with the bichromatic driving\nare discussed. The realization of the Rabi resonance using the radiofrequency\nfield could open new possibilities for separating the contributions of\nrelaxation mechanisms from those due to the inhomogeneous driving in spin\ndecoherence.",
        "positive": "Universal Lindblad equation for open quantum systems: We develop a Markovian master equation in the Lindblad form that enables the\nefficient study of a wide range of open quantum many-body systems that would be\ninaccessible with existing methods. The validity of the master equation is\nbased entirely on properties of the bath and the system-bath coupling, without\nany requirements on the level structure within the system itself. The master\nequation is derived using a Markov approximation that is distinct from that\nused in earlier approaches. We provide a rigorous bound for the error induced\nby this Markov approximation; the error is controlled by a dimensionless\ncombination of intrinsic correlation and relaxation timescales of the bath. Our\nmaster equation is accurate on the same level of approximation as the\nBloch-Redfield equation. In contrast to the Bloch-Redfield approach, our\napproach ensures preservation of the positivity of the density matrix. As a\nresult, our method is robust, and can be solved efficiently using stochastic\nevolution of pure states (rather than density matrices). We discuss how our\nmethod can be applied to static or driven quantum many-body systems, and\nillustrate its power through numerical simulation of a spin chain that would be\nchallenging to treat by existing methods."
    },
    {
        "anchor": "Proposal for a Detector of Photons with Zero Projection of Spin: We suggest an indirect method of detection of photons with zero projection of\nspin mediated by emission of terahertz photons. This terahertz source is based\non a system of microcavity exciton polaritons in the regime of polariton BEC\nformation when the cavity photons acquire an effective mass being localised in\nthe cavity and therefore receive the third spin degree of freedom\n(corresponding to the longitudinal polarization with chirality l = 0). The\noptical transitions can occur between two polariton ground states based on the\nlight-hole and heavy-hole excitons, respectively, accompanied by the emission\nof terahertz radiation with controllable characteristics. We calculate the\ndipole matrix element of such transitions and corresponding rate of spontaneous\nemission for a realistic cavity based on InAlGaAs alloys, investigate its\ndynamics and estimate quantum efficiency of the terahertz source.",
        "positive": "Quantum Hall Phase Diagram of Half-filled Bilayers in the Lowest and the\n  Second Orbital Landau Levels: Abelian versus Non-Abelian Incompressible\n  Fractional Quantum Hall States: We examine the quantum phase diagram of the fractional quantum Hall effect\n(FQHE) in the lowest two Landau levels in half-filled bilayer structures as a\nfunction of tunneling strength and layer separation, i.e., we revisit the\nlowest Landau level filling factor 1/2 bilayer problem and make new predictions\ninvolving bilayers in the half-filled second Landau level (i.e., filling factor\n5/2). Using numerical exact diagonalization we investigate the important\nquestion of whether this system supports a FQHE described by the non-Abelian\nMoore-Read Pfaffian state in the strong tunneling regime. In the lowest Landau\nlevel, we find that although in principle, increasing (decreasing) tunneling\nstrength (layer separation) could lead to a transition from the Abelian\ntwo-component Halperin 331 to non-Abelian one-component Moore-Read Pfaffian\nstate, the FQHE excitation gap is relatively small in the lowest Landau level\nPfaffian regime--we establish that all so far observed FQHE states in\nhalf-filled lowest Landau level bilayers are most likely described by the\nAbelian Halperin 331 state. In the second Landau level we make the prediction\nthat bilayer structures would manifest two distinct branches of incompressible\nFQHE corresponding to the Abelian 331 state (at moderate to low tunneling and\nlarge layer separation) and the non-Abelian Moore-Read Pfaffian state (at large\ntunneling and small layer separation). The observation of these two FQHE\nbranches and the possible quantum phase transition between them will be\ncompelling evidence supporting the existence of the non-Abelian Moore-Read\nPfaffian state in the second Landau level. We discuss our results in the\ncontext of existing experiments and theoretical works."
    },
    {
        "anchor": "Multiquantum well spin oscillator: A dc voltage biased II-VI semiconductor multiquantum well structure attached\nto normal contacts exhibits self-sustained spin-polarized current oscillations\nif one or more of its wells are doped with Mn. Without magnetic impurities, the\nonly configurations appearing in these structures are stationary. Analysis and\nnumerical solution of a nonlinear spin transport model yield the minimal number\nof wells (four) and the ranges of doping density and spin splitting needed to\nfind oscillations.",
        "positive": "Carrier-envelope phase effects in graphene: We numerically study the interaction of a terahertz pulse with monolayer\ngraphene. We observe that the electron momentum density is affected by the\ncarrier-envelope phase (CEP) of the single- to few-cycle terahertz laser pulse\nthat induces the electron dynamics. In particular, we see strong asymmetric\nelectron momentum distributions for non-zero values of the CEP. We explain the\norigin of the asymmetry within the adiabatic-impulse model by finding\nconditions to reach minimal adiabatic gap between the valence band and the\nconduction band. We discuss how these conditions and the interference pattern,\nemanating from successive non-adiabatic transitions at this minimal gap, affect\nthe electron momentum density and how they are modified by the CEP. This opens\nthe door to control fundamental time-dependent electron dynamics in the\ntunneling regime in Dirac materials. Also, this control suggests a way to\nmeasure the CEP of a terahertz laser pulse when it interacts with condensed\nmatter systems."
    },
    {
        "anchor": "Resonant electron transfer between quantum dots: An interaction of electromagnetic field with a nanostructure composed of two\nquantum dots is studied theoretically. An effect of a resonant electron\ntransfer between the localized low-lying states of quantum dots is predicted. A\nnecessary condition for such an effect is the existence of an excited bound\nstate whose energy lies close to the top of the barrier separating the quantum\ndots. This effect may be used to realize the reversible quantum logic gate NOT\nif the superposition of electron states in different quantum dots is viewed as\nthe superposition of bits 0 and 1.",
        "positive": "Two-channel Kondo effect and renormalization flow with macroscopic\n  quantum charge states: Many-body correlations and macroscopic quantum behaviors are fascinating\ncondensed matter problems. A powerful test-bed for the many-body concepts and\nmethods is the Kondo model which entails the coupling of a quantum impurity to\na continuum of states. It is central in highly correlated systems and can be\nexplored with tunable nanostructures. Although Kondo physics is usually\nassociated with the hybridization of itinerant electrons with microscopic\nmagnetic moments, theory predicts that it can arise whenever degenerate quantum\nstates are coupled to a continuum. Here we demonstrate the previously elusive\n`charge' Kondo effect in a hybrid metal-semiconductor implementation of a\nsingle-electron transistor, with a quantum pseudospin-1/2 constituted by two\ndegenerate macroscopic charge states of a metallic island. In contrast to other\nKondo nanostructures, each conduction channel connecting the island to an\nelectrode constitutes a distinct and fully tunable Kondo channel, thereby\nproviding an unprecedented access to the two-channel Kondo effect and a clear\npath to multi-channel Kondo physics. Using a weakly coupled probe, we reveal\nthe renormalization flow, as temperature is reduced, of two Kondo channels\ncompeting to screen the charge pseudospin. This provides a direct view of how\nthe predicted quantum phase transition develops across the symmetric quantum\ncritical point. Detuning the pseudospin away from degeneracy, we demonstrate,\non a fully characterized device, quantitative agreement with the predictions\nfor the finite-temperature crossover from quantum criticality."
    },
    {
        "anchor": "Controlling the Interferometers of Zero-Line Modes in Graphene by\n  Pseudomagnetic field: Networks of graphene-based topological domain walls function as nano-scale\ninterferometers of zero-line modes, with magnetic field and(or) scalar\npotential as the controlling parameters. In the absence of externally applied\nmagnetic or electrical field, strain induces pseudomagnetic field and scalar\npotential in graphene, which could control the interferometers more\nefficiently. Two types of strains are considered: (i) Horizontally bending the\ngraphene nanoribbon into circular arc induces nearly uniform pseudomagnetic\nfield; (ii) Helicoidal graphene nanoribbon exhibit nonuniform pseudomagnetic\nfield. Both types of strain induce small scalar potential due to dilatation.\nThe interferometers are studied by transport calculation of the tight binding\nmodel. The transmission rates through the interferometer depend on the strain\nparameters. An interferometer with three loops is designed, which could\ncompletely switch the transmitting current from one export to the other.",
        "positive": "Spin Orientation of Holes in Quantum Wells: This paper reviews the spin orientation of spin-3/2 holes in quantum wells.\nWe discuss the Zeeman and Rashba spin splitting in hole systems that are\nqualitatively different from their counterparts in electron systems. We show\nhow a systematic understanding of the unusual spin-dependent phenomena in hole\nsystems can be gained using a multipole expansion of the spin density matrix.\nAs an example we discuss spin precession in hole systems that can give rise to\nan alternating spin polarization. Finally, we discuss the qualitatively\ndifferent regimes of hole spin polarization decay in clean and dirty samples."
    },
    {
        "anchor": "Energetic optimization effects in single resonant tunneling\n  $GaAs$--nanoconverters: Several models of thermionic energy nanoconverters have been proposed to\nstudy the transport phenomena that take place in electronic devices. For\nexample, in resonant tunneling junctions those phenomena are manifested through\nthe thermoelectric effects. The coupling between the electron flux and the heat\nflux in this type of semiconductor heterostructures, not only allows to obtain\ntransport coefficients (electrical and thermal conductivities, and a\nSeebeck--like and Peltier--like coefficients), but also to study its operation\nas a thermionic generator or as a refrigerator within the context of\nirreversible thermodynamics. The existence of the characteristic steady states\nthat can be reached by any linear energy converter led us to characterize a\nfamily of Seebeck--like coefficients, as well as establish bounds for the\nvalues of a kind of figure of merit $(Tz'_{D,I})$, both associated with the\nwell-known operating regimes: minimum dissipation function, maximum power\noutput, maximum efficiency and maximum compromise function. By taking as\nexample an $Al_{x}GaAs/GaAs$ junction, we found that the transport coefficients\ndepend strongly on temperature and the conduction band height, which can be\nmodulated according to the selected operation mode.",
        "positive": "Spectroscopy of van der Waals nanomaterials: Opportunities and\n  Challenges: The study of van der Waals (vdW) materials has seen increased interest in\nrecent years, due to the wide range of uses for these materials because of\ntheir unique mechanical, electronic, and optical properties. This area has\nrecently expanded further into studying the behavior of vdW nanomaterials, as\ndecreasing dimensions open up opportunities to interact with these materials in\nnew ways. However, measuring the band structures of nanomaterials, which is key\nto understanding how confinement affects material properties and interactions,\ncomes with several challenges. In this review, we survey a range of techniques\nfor synthesizing and characterizing vdW nanomaterials, in order to outline the\nkey material and characterization challenges. This includes controlling the\nFermi level in vdW nanoparticles, preparing these particles for either ensemble\nor individual particle measurement, as well as protecting the pristine surface\nfrom oxidation."
    },
    {
        "anchor": "Optomagnonic whispering gallery microresonators: Magnons in ferrimagnetic insulators such as yttrium iron garnet (YIG) have\nrecently emerged as promising candidates for coherent information processing in\nmicrowave circuits. Here we demonstrate optical whispering gallery modes of a\nYIG sphere interrogated by a silicon nitride photonic waveguide, with quality\nfactors approaching $10^6$ in the telecom c-band after surface treatments.\nMoreover, in contrast to conventional Faraday setup, this implementation allows\ninput photon polarized colinearly to the magnetization to be scattered to a\nsideband mode of orthogonal polarization. This Brillouin scattering process is\nenhanced through triply resonant magnon, pump and signal photon modes - all of\nwhispering gallery nature - within an \"optomagnonic cavity\". Our results show\nthe potential use of magnons for mediating microwave-to-optical carrier\nconversion.",
        "positive": "Virial Coefficients of Multispecies Anyons: A path integral formalism for multispecies anyons is introduced, whereby\npartition functions are expressed in terms of generating functions of winding\nnumber probability distributions. In a certain approximation, the equation of\nstate for exclusion statistics follows. By Monte Carlo simulation, third-order\ncluster and virial coefficients are found numerically."
    },
    {
        "anchor": "Prospects for single-molecule electrostatic detection in molecular motor\n  gliding motility assays: Molecular motor gliding motility assays based on myosin/actin or\nkinesin/microtubules are of interest for nanotechnology applications ranging\nfrom cargo-trafficking in lab-on-a-chip devices to novel biocomputation\nstrategies. Prototype systems are typically monitored by expensive and bulky\nfluorescence microscopy systems and the development of integrated, direct\nelectric detection of single filaments would strongly benefit applications and\nscale-up. We present estimates for the viability of such a detector by\ncalculating the electrostatic potential change generated at a carbon nanotube\ntransistor by a motile actin filament or microtubule under realistic gliding\nassay conditions. We combine this with detection limits based on previous\nstate-of-the-art experiments using carbon nanotube transistors to detect\ncatalysis by a bound lysozyme molecule and melting of a bound short-strand DNA\nmolecule. Our results show that detection should be possible for both actin and\nmicrotubules using existing low ionic strength buffers given good device\ndesign, e.g., by raising the transistor slightly above the guiding channel\nfloor. We perform studies as a function of buffer ionic strength, height of the\ntransistor above the guiding channel floor, presence/absence of the casein\nsurface passivation layer for microtubule assays and the linear charge density\nof the actin filaments/microtubules. We show that detection of microtubules is\na more likely prospect given their smaller height of travel above the surface,\nhigher negative charge density and the casein passivation, and may possibly be\nachieved with the nanoscale transistor sitting directly on the guiding channel\nfloor.",
        "positive": "Anomalous transport phenomena in Weyl metal beyond the Drude model for\n  Landau's Fermi liquids: Landau's Fermi-liquid theory is the standard model for metals, characterized\nby the existence of electron quasiparticles near a Fermi surface as long as\nLandau's interaction parameters lie below critical values for instabilities.\nRecently, this fundamental paradigm has been challenged by physics of strong\nspin-orbit coupling although the concept of electron quasiparticles remains\nvalid near the Fermi surface, where the Landau's Fermi-liquid theory fails to\ndescribe electromagnetic properties of this novel metallic state, referred to\nas Weyl metal. A novel ingredient is that such a Fermi surface encloses a Weyl\npoint with definite chirality, referred to as a chiral Fermi surface, which can\narise from breaking of either time reversal or inversion symmetry in systems\nwith strong spin-orbit coupling, responsible for both Berry curvature and\nchiral anomaly. As a result, electromagnetic properties of the Weyl metallic\nstate are described not by conventional Maxwell equations but by axion\nelectrodynamics, where Maxwell equations are modified with a\ntopological-in-origin spatially modulated $\\theta(\\bm{r}) \\bm{E} \\cdot \\bm{B}$\nterm. This novel metallic state has been realized recently in\nBi$_{1-x}$Sb$_{x}$ around $x \\sim 3%$ under magnetic fields, where the Dirac\nspectrum appears around the critical point between the normal semiconducting\n($x < 3%$) and topological semiconducting phases ($x > 3%$) and the time\nreversal symmetry breaking perturbation causes the Dirac point to split into a\npair of Weyl points along the direction of the applied magnetic field for such\na strong spin-orbit coupled system. In this review article, we discuss how the\ntopological structure of both the Berry curvature and chiral anomaly (axion\nelectrodynamics) gives rise to anomalous transport phenomena in\nBi$_{1-x}$Sb$_{x}$ around $x \\sim 3%$ under magnetic fields, modifying the\nDrude model of Landau's Fermi liquids."
    },
    {
        "anchor": "Adiabatic observables and Berry curvatures in insulators and metals: A sharp definition of what \"adiabatic\" means is given; it is then shown that\nthe time-dependent expectation value of a quantum-mechanical observable in the\nadiabatic limit can be expressed -- in many cases -- by means of the\nappropriate Berry curvature. Condensed-matter observables belonging to this\nclass include: Born effective charges in insulators and in metals, quantized\nFaraday charges in electrolytes, and linear dc conductivities (longitudinal and\ntransverse). Remarkably, the adiabatic limit is well defined even in metals,\ndespite the absence of a spectral gap therein. For all of the above observables\nthe explicit Berry-curvature expressions are derived in a general many-body\nsetting, which also allows for compact and very transparent notations and\nformulas. Their conversion into band-structure formulas in the\nindependent-electron crystalline case is straightforward.",
        "positive": "Time-Reversal Soliton Pairs In Even Spin-Chern-Number Higher-Order\n  Topological Insulators: Solitons formed through the one-dimensional mass-kink mechanism on the edges\nof two-dimensional systems with non-trivial topology play an important role in\nthe emergence of higher-order (HO) topological phases. In this connection, the\nexisting work in time-reversal symmetric systems has focused on gapping the\nedge Dirac cones in the presence of particle-hole symmetry, which is not suited\nto the common spin-Chern insulators. Here, we address the emergence of edge\nsolitons in spin-Chern number of $2$ insulators, in which the edge Dirac cones\nare gapped by perturbations preserving time-reversal symmetry but breaking\nspin-$U(1)$ symmetry. Through the mass-kink mechanism, we thus explain the\nappearance of pairwise corner modes and predict the emergence of extra charges\naround the corners. By tracing the evolution of the mass term along the edge,\nwe demonstrate that the in-gap corner modes and the associated extra charges\ncan be generated through the $S_z$-mixing spin-orbit coupling via the mass-kink\nmechanism. We thus provide strong evidence that an even spin-Chern-number\ninsulator is an HO topological insulator with protected corner charges."
    },
    {
        "anchor": "Resonant Tunneling through double-bended Graphene Nanoribbons: We investigate theoretically resonant tunneling through double-bended\ngraphene nanoribbon structures, i.e., armchair-edged graphene nanoribbons\n(AGNRs) in between two semi-infinite zigzag graphene nanoribbon (ZGNR) leads.\nOur numerical results demonstrate that the resonant tunneling can be tuned\ndramatically by the Fermi energy and the length and/or widths of the AGNR for\nboth the metallic and semiconductor-like AGNRs. The structure can also be use\nto control the valley polarization of the tunneling currents and could be\nuseful for potential application in valleytronics devices.",
        "positive": "Magnetism and Magneto-optical Effects in Bulk and Few-layer CrI$_3$: A\n  Theoretical GGA + U Study: The latest discovery of ferromagnetism in atomically thin films of\nsemiconductors Cr$_2$Ge$_2$Te$_6$ and CrI$_3$ has unleashed numerous\nopportunities for fundamental physics of magnetism in two-dimensional (2D)\nlimit and also for technological applications based on 2D magnetic materials.\nIn this paper, we present a comprehensive theoretical study of the magnetic,\nelectronic, optical and magneto-optical(MO) properties of multilayers\n[monolayer(ML), bilayer and trilayer] and bulk CrI$_3$, based on the density\nfunctional theory with the generalized gradient approximation plus on-site\nCoulomb repulsion scheme. Interestingly, all the structures are found to be\nsingle-spin ferromagnetic(FM) semiconductors. They all have a large\nout-of-plane magnetic anisotropy energy(MAE) of $\\sim$0.5 meV/Cr. These large\nMAEs suppress transverse spin fluctuations and thus stabilize long-range\nmagnetic orders at finite temperatures down to the ML limit. They also exhibit\nstrong MO effects with their Kerr and Faraday rotation angles being comparable\nto that of best-known bulk MO materials. The shape and position of the main\nfeatures in the optical and MO spectra are found to be nearly\nthickness-independent although the magnitude of Kerr rotation angles increases\nmonotonically with the film thickness. Magnetic transition temperatures\nestimated based on calculated exchange coupling parameters, calculated optical\nconductivity, MO Kerr and Faraday rotation angles agree quite well with\navailable experimental data. The calculated MAE as well as optical and MO\nproperties are analyzed in terms of the calculated orbital-decomposed densities\nof states, band state symmetries and dipole selection rules. Our findings of\nlarge out-of-plane MAEs and strong MO effects in these single-spin FM\nsemiconducting CrI$_3$ ultrathin films suggest that they will find valuable\napplications in semiconductor MO and spintronic nanodevices."
    },
    {
        "anchor": "Anomalous Hall Effect in Variable Range Hopping Regime: Unusual Scaling\n  Law and Sign Reversal with Temperature: Anomalous Hall effect (AHE) is important for understanding the topological\nproperties of electronic states, and provides insight into the spin-polarized\ncarriers of magnetic materials. AHE has been extensively studied in metallic,\nbut not variable-range-hopping (VRH), regime. Here we report the experiments of\nboth anomalous and ordinary Hall effect (OHE) in Mott and Efros VRH regimes. We\nfound unusual scaling law of the AHE coefficient $Rah=aRxx^b$ with b>2,\ncontrasting the OHE coefficient $Roh=cRxx^d$ with d<1. More strikingly, the\nsign of AHE coefficient changes with temperature with specific electron\ndensities.",
        "positive": "Quantum kinetic theory of nonlinear thermal current: We investigate the second-order nonlinear electronic thermal transport\ninduced by temperature gradient. We develop the quantum kinetic theory\nframework to describe thermal transport in presence of a temperature gradient.\nUsing this, we predict an intrinsic scattering time independent nonlinear\nthermal current in addition to the known extrinsic nonlinear Drude and Berry\ncurvature dipole contributions. We show that the intrinsic thermal current is\ndetermined by the band geometric quantities and is non-zero only in systems\nwhere both the space inversion and time-reversal symmetries are broken. We\nemploy the developed theory to study the thermal response in tilted massive\nDirac systems. We show that besides the different scattering time dependence,\nthe various current contributions have distinct temperature dependence in the\nlow temperature limit. Our systematic and comprehensive theory for nonlinear\nthermal transport paves the way for future theoretical and experimental studies\non intrinsic thermal responses."
    },
    {
        "anchor": "Brightened spin-triplet interlayer excitons and optical selection rules\n  in van der Waals heterobilayers: We investigate the optical properties of spin-triplet interlayer excitons in\nheterobilayer transition metal dichalcogenides in comparison with the\nspin-singlet ones. Surprisingly, the optical transition dipole of the\nspin-triplet exciton is found to be in the same order of magnitude to that of\nthe spin-singlet exciton, in sharp contrast to the monolayer excitons where the\nspin triplet species is considered as dark compared to the singlet. Unlike the\nmonolayer excitons whose spin-conserved (spin-flip) transition dipole can only\ncouple to light of in-plane (out-of-plane) polarization, such restriction is\nremoved for the interlayer excitons due to the breaking of the out-of-plane\nmirror symmetry. We find that as the interlayer atomic registry changes, the\noptical transition dipole of interlayer exciton crosses between in-plane ones\nof opposite circular polarization and the out-of-plane one for both the\nspin-triplet and spin-singlet species. As a result, excitons of both species\nhave non-negligible coupling into photon modes of both in-plane and\nout-of-plane propagations, another sharp difference from the monolayers where\nthe exciton couples predominantly into the out-of-plane propagation channel. At\ngiven atomic registry, the spin-triplet and spin-singlet excitons have distinct\nvalley polarization selection rules, allowing the selective optical addressing\nof both the valley configuration and the spin singlet/triplet configuration of\ninterlayer excitons.",
        "positive": "Spin-wave chirality and its manifestations in antiferromagnets: As first demonstrated by Tang and Cohen in chiral optics, the asymmetry in\nthe rate of electromagnetic energy absorption between left and right\nenantiomers is determined by an optical chirality density [1]. Here, we\ndemonstrate that this effect can exist in magnetic spin systems. By\nconstructing a formal analogy with electrodynamics, we show that in\nantiferromagnets with broken chiral symmetry the asymmetry in local spin-wave\nenergy absorption is proportional to a spin-wave chirality density, which is a\ndirect counterpart of optical zilch. We propose that injection of a pure spin\ncurrent into an antiferromagnet may serve as a chiral symmetry breaking\nmechanism, since its effect in the spin-wave approximation can be expressed in\nterms of additional Lifshitz invariants. We use linear response theory to show\nthat the spin current induces a nonequilibrium spin-wave chirality density."
    },
    {
        "anchor": "Rashba coupling induced spin susceptibility and magnetic phase\n  transition of conduction electrons in monolayer graphene: Using the Kubo formalism, the magnetic properties of the system in the linear\nregime have been investigated. Mainly the effect of non-magnetic substrate on\nthe spin susceptibility is calculated. Results show that the Rashba coupling\ninteraction has a central role in the magnetic response function of the system\nand it is really remarkable since this type of spin orbit coupling can be\neffectively controlled by an external gate voltage. Most importantly it was\nshown that, in the presence of the Rashba interaction a magnetic phase\ntransition could be observed. This magnetic phase corresponds to a magnetic\norder of conduction electrons that takes place at some especial frequency of\nexternal magnetic field.",
        "positive": "Modelling impurity-assisted chain creation in noble-metal break\n  junctions: In this work we present the generalization of the model for chain formation\nin break-junctions, introduced by Thiess {\\it et al.} [\\onlinecite{Alex08}], to\nzigzag transition-metal chains with $s$ and $p$ impurities. We apply this\nextended model to study the producibility trends for noble-metal chains with\nimpurities, often present in break junction experiments, namely, Cu, Ag and Au\nchains with H, C, O and N adatoms. Providing the material-specific parameters\nfor our model from systematic full-potential linearized augmented plane-wave\nfirst-principles calculations, we find that the presence of such impurities\ncrucially affects the binding properties of the noble-metal chains. We reveal\nthat both, the impurity-induced bond strengthening and the formation of zigzag\nbonds, can lead to a significantly enhanced probability for chain formation in\nbreak junctions."
    },
    {
        "anchor": "Quantum anomalous Hall effect in atomic crystal layers from in-plane\n  magnetization: We theoretically report that, with \\textit{in-plane} magnetization, the\nquantum anomalous Hall effect (QAHE) can be realized in two-dimensional atomic\ncrystal layers with preserved inversion symmetry but broken out-of-plane mirror\nreflection symmetry. We take the honeycomb lattice as an example, where we find\nthat the low-buckled structure, which makes the system satisfy the symmetric\ncriteria, is crucial to induce QAHE. The topologically nontrivial bulk gap\ncarrying a Chern number of $\\mathcal{C}=\\pm1$ opens in the vicinity of the\nsaddle points $M$, where the band dispersion exhibits strong anisotropy. We\nfurther show that the QAHE with electrically tunable Chern number can be\nachieved in Bernal-stacked multilayer systems, and the applied interlayer\npotential differences can dramatically decrease the critical magnetization to\nmake the QAHE experimentally feasible.",
        "positive": "Replacing Leads by Self-Energies Using Nonequilibrium Green's Functions: An open quantum system consists of leads connected to a device of interest.\nWithin the nonequilibrium Green's function technique, we examine the\nreplacement of leads by self-energies in continuum calculations. Our starting\npoint is a formulation of the problem for continuum systems by T.E. Feuchtwang.\nIn this approach there is considerable flexibility in the choice of unperturbed\nGreen's functions. We examine the consequences of this freedom on the treatment\nof leads. For any choice the leads can be replaced by coupling self-energies\nwhich are simple functions of energy. We find that the retarded self-energy\ndepends on the details of the choice of unperturbed Green's function, and can\ntake any value. However, the nonequilibrum self-energy or scattering function\ncan be taken to be independent of this choice. Expressed in terms of these\nself-energies, nonequilibrium transport calculations take a particularly simple\nform."
    },
    {
        "anchor": "Tunable electronic transport and unidirectional quantum wires in\n  graphene subjected to electric and magnetic fields: Magnetic barriers in graphene are not easily tunable. However, introducing\nboth electric and magnetic fields, provides tunable and far more controllable\nelectronic states in graphene. Here we study such systems. A one-dimensional\nchannel can be formed in graphene using perpendicular electric and magnetic\nfields. This channel (quantum wire) supports localized electron-hole states,\nwith parameters that can be controlled by an electric field. Such quantum wire\noffers peculiar conducting properties, like unidirectional conductivity and\nrobustness to disorder. Two separate quantum wires comprise a waveguide with\ntwo types of eigenmodes: one type is similar to traditional waveguides, the\nother type is formed by coupled surface waves propagating along the boundaries\nof the waveguide.",
        "positive": "Floquet Engineering of Magnetism in Topological Insulator Thin Films: Dynamic manipulation of magnetism in topological materials is demonstrated\nhere via a Floquet engineering approach using circularly polarized light.\nIncreasing the strength of the laser field, besides the expected topological\nphase transition, the magnetically doped topological insulator thin film also\nundergoes a magnetic phase transition from ferromagnetism to paramagnetism,\nwhose critical behavior strongly depends on the quantum quenching. In sharp\ncontrast to the equilibrium case, the non-equilibrium Curie temperatures vary\nfor different time scale and experimental setup, not all relying on change of\ntopology. Our discoveries deepen the understanding of the relationship between\ntopology and magnetism in the non-equilibrium regime and extend optoelectronic\ndevice applications to topological materials."
    },
    {
        "anchor": "Analytic Theory of Edge Modes in Topological Insulators: Spectrum and wave function of gapless edge modes are derived analytically for\na tight-binding model of topological insulators on square lattice. Particular\nattention is paid to dependence on edge geometries such as the straight (1,0)\nand zigzag (1,1) edges in the thermodynamic limit. The key technique is to\nidentify operators that combine to annihilate the edge state in the effective\none-dimensional (1D) model with momentum along the edge. In the (1,0) edge, the\nedge mode is present either around the center of 1D Brillouin zone or its\nboundary, depending on location of the bulk excitation gap. In the (1,1) edge,\nthe edge mode is always present both at the center and near the boundary.\nDepending on system parameters, however, the mode is absent in the middle of\nthe Brillouin zone. In this case the binding energy of the edge mode near the\nboundary is extremely small; about $10^{-3}$ of the overall energy scale.\nOrigin of this minute energy scale is discussed.",
        "positive": "Theory of multiexciton generation in semiconductor nanocrystals: We develop a generalized framework based on a Green's function formalism to\ncalculate the efficiency of multiexciton gen-eration in nanocrystal quantum\ndots. The direct/indirect absorption and coherent/incoherent impact ionization\nmechanisms, often used to describe multiexciton generation in nanocrystals, are\nreviewed and rederived from the unified theory as certain approximations. In\naddition, two new limits are described systematically - the weak Coulomb\ncoupling limit and the semi-wide band limit. We show that the description of\nmultiexciton generation in nanocrystals can be described as incoherent process\nand we discuss the scaling of multiexciton generation with respect to the\nphoton energy and nanocrystal size. Illustrations are given for three prototype\nsystems: CdSe, InAs and silicon quantum dots."
    },
    {
        "anchor": "Spin readout of a CMOS quantum dot by gate reflectometry and\n  spin-dependent tunnelling: Silicon spin qubits are promising candidates for realising large scale\nquantum processors, benefitting from a magnetically quiet host material and the\nprospects of leveraging the mature silicon device fabrication industry. We\nreport the measurement of an electron spin in a singly-occupied gate-defined\nquantum dot, fabricated using CMOS compatible processes at the 300 mm wafer\nscale. For readout, we employ spin-dependent tunneling combined with a\nlow-footprint single-lead quantum dot charge sensor, measured using\nradiofrequency gate reflectometry. We demonstrate spin readout in two devices\nusing this technique, obtaining valley splittings in the range 0.5-0.7 meV\nusing excited state spectroscopy, and measure a maximum electron spin\nrelaxation time ($T_1$) of $9 \\pm 3$ s at 1 Tesla. These long lifetimes\nindicate the silicon nanowire geometry and fabrication processes employed here\nshow a great deal of promise for qubit devices, while the spin-readout method\ndemonstrated here is well-suited to a variety of scalable architectures.",
        "positive": "Electronic transport in bent carbon nanotubes: We study the electronic transport through uniformly bent carbon nanotubes.\nFor this purpose, we describe the nanotube with the tight-binding model and\ncalculate the local current flow by employing non-equilibrium Green's functions\n(NEGF) in the Keldysh formalism. In addition, we describe the low-energy\nexcitations using an effective Dirac equation in curved space with a\nstrain-induced pseudo-magnetic field which can be solved analytically for the\ntorus geometry in terms of the Mathieu functions. We obtain a perfect\nquantitative agreement with the NEGF results. For nanotubes with an armchair\nedge, already a weak bending of 1% substantially changes the electronic\nproperties. Depending on the valley, the current of the zero mode flows either\non the outer or the inner side of the torus and, therefore, can be used as a\nvalley splitter. In contrast, the zigzag nanotubes are largely unaffected by\nthe bending. Our findings are of importance for nanoelectronic applications of\ncarbon nanotubes and open new possibilities for valleytronics."
    },
    {
        "anchor": "Nonadiabatic Electron Manipulation in Quantum-Dot Arrays: A novel method of coherent manipulation of the electron tunneling in\nquantum-dots is proposed, which utilizes the quantum interference in\nnonadiabatic double-crossing of the discrete energy levels. In this method, we\nneed only a smoothly varying gate voltage to manipulate electrons, without a\nsudden switching-on and off. A systematic design of a smooth gate-pulse is\npresented with a simple analytic formula to drive the two-level electronic\nstate to essentially arbitrary target state, and numerical simulations for\ncomplete transfer of an electron is shown for a coupled double quantum-dots and\nan array of quantum-dots. Estimation of the manipulation-time shows that the\npresent method can be employed in realistic quantum-dots.",
        "positive": "Floquet Scattering Theory based on Effective Hamiltonians of Driven\n  Systems: The design of time-independent effective Hamiltonians that describe\nperiodically modulated systems, provides a promising approach to realize new\nforms of matter. This, so-called, Floquet engineering approach is currently\nlimited to the description of wavepacket dynamics. Here, we utilize the notion\nof effective Hamiltonians and develop a Floquet engineering scattering\nformalism that relies on a systematic high-frequency expansion of the\nscattering matrix. The method unveils the critical role of micromotion. An\napplication to the case of non-reciprocal transport is presented."
    },
    {
        "anchor": "Topological phase transition from trigonal warping in van der Waals\n  multilayers: In van der Waals multilayers of triangular lattice, trigonal warping occurs\nuniversally due to the interlayer hopping. We theoretically investigate the\neffect of trigonal warping upon distinctive topological phases, like the\nquantum anomalous Hall effect (QAHE) and the quantum valley Hall effect (QVHE).\nTaking Bernal-stacked bilayer graphene as an example, we find that the trigonal\nwarping plays a crucial role in the formation of QAHE in large exchange field\nand/or interlayer potential difference by inducing extra band inversion points\nat momentum further away from high symmetric point. The presence of trigonal\nwarping shrinks the phase space of QAHE and QVHE, leading to the emergence of\nvalley-polarized QAHE with high Chern numbers ranging from $ \\mathcal{C}=-7 $\nto $ 7 $. These results suggest that the universal trigonal warping may play\nimportant role when the Bloch states at momentum away from high-symmetric\npoints are involved.",
        "positive": "Origin of the quasi-universality of the graphene minimal conductivity: It is a fact that the minimal conductivity $\\sigma_0$ of most graphene\nsamples is larger than the well-established universal value for ideal graphene\n$4e^2/\\pi h$; in particular, larger by a factor $\\gtrsim\\pi$. Despite intense\ntheoretical activity, this fundamental issue has eluded an explanation so far.\nHere we present fully atomistic quantum mechanical estimates of the graphene\nminimal conductivity where electron-electron interactions are considered in the\nframework of density functional theory. We show the first conclusive evidence\nof the dominant role on the minimal conductivity of charged impurities over\nripples, which have no visible effect. Furthermore, in combination with the\nlogarithmic scaling law for diffusive metallic graphene, we ellucidate the\norigin of the ubiquitously observed minimal conductivity in the range $8e^2/h >\n\\sigma_0 \\gtrsim 4e^2/h$."
    },
    {
        "anchor": "Chiral anomaly and anomalous finite-size conductivity in graphene: Graphene is a monolayer of carbon atoms packed into a hexagon lattice to host\ntwo pairs of massless two-dimensional Dirac fermions in the absence of or with\nnegligible spin-orbit coupling. It is known that the existence of non-zero\nelectric polarization in reduced momentum space which is associated with a\nhidden chiral symmetry will lead to the zero-energy flat band of zigzag\nnanoribbon. The Adler-Bell-Jackiw chiral anomaly or non-conservation of chiral\ncharges at different valleys can be realized in a confined ribbon of finite\nwidth. In the laterally diffusive regime, the finite-size correction to\nconductivity is always positive and goes inversely with the square of the\nlateral dimension W, which is different from the finite-size correction\ninversely with W from boundary modes. This anomalous finite-size conductivity\nreveals the signature of the chiral anomaly in graphene, and is measurable\nexperimentally.",
        "positive": "Atomically thin mirrors made of monolayer semiconductors: Transition metal dichalcogenide monolayers are promising candidates for\nexploring new electronic and optical phenomena and for realizing atomically\nthin optoelectronic devices. They host tightly bound electron-hole pairs\n(excitons) that can be efficiently excited by resonant light fields. Here, we\ndemonstrate that a single monolayer of molybdenum diselenide (MoSe2) can\ndramatically modify light transmission near the excitonic resonance, acting as\nan electrically switchable mirror that reflects up to 85% of incident light at\ncryogenic temperatures. This high reflectance is a direct consequence of the\nexcellent coherence properties of excitons in this atomically thin\nsemiconductor, encapsulated by hexagonal boron nitride. Furthermore, we show\nthat the MoSe2 monolayer exhibits power- and wavelength-dependent\nnonlinearities that stem from exciton-based lattice heating in the case of\ncontinuous-wave excitation and exciton-exciton interactions when fast, pulsed\nlaser excitation is used. These observations open up new possibilities for\nstudying quantum nonlinear optical phenomena and topological photonics, and for\nminiaturizing optical devices."
    },
    {
        "anchor": "Nanometre-scale probing of spin waves using single electron spins: Correlated-electron systems support a wealth of magnetic excitations, ranging\nfrom conventional spin waves to exotic fractional excitations in\nlow-dimensional or geometrically-frustrated spin systems. Probing such\nexcitations on nanometre length scales is essential for unravelling the\nunderlying physics and developing new spintronic nanodevices. However, no\nestablished technique provides real-space, few-nanometre-scale probing of\ncorrelated-electron magnetic excitations under ambient conditions. Here we\npresent a solution to this problem using magnetometry based on single\nnitrogen-vacancy (NV) centres in diamond. We focus on spin-wave excitations in\na ferromagnetic microdisc, and demonstrate local, quantitative, and\nphase-sensitive detection of the spin-wave magnetic field at ~50 nm from the\ndisc. We map the magnetic-field dependence of spin-wave excitations by\ndetecting the associated local reduction in the disc's longitudinal\nmagnetization. In addition, we characterize the spin-noise spectrum by NV-spin\nrelaxometry, finding excellent agreement with a general analytical description\nof the stray fields produced by spin-spin correlations in a 2D magnetic system.\nThese complementary measurement modalities pave the way towards imaging the\nlocal excitations of systems such as ferromagnets and antiferromagnets,\nskyrmions, atomically assembled quantum magnets, and spin ice.",
        "positive": "Ground-state characterization of Nb charge-phase Josephson qubits: We present investigations of Josephson charge-phase qubits inductively\ncoupled to a radio-frequency driven tank-circuit enabling the readout of the\nstates by measuring the Josephson inductance of the qubit. The circuits\nincluding junctions with linear dimensions of 60 nm and 80 nm are fabricated\nfrom Nb trilayer and allowing the determination of relevant sample parameters\nat liquid helium temperature. The observed partial suppression of the\ncirculating supercurrent at 4.2 K is explained in the framework of a quantum\nstatistical model. We have probed the ground-state properties of qubit\nstructures with different ratios of the Josephson coupling to Coulomb charging\nenergy at 20 mK, demonstrating both the magnetic control of phase and the\nelectrostatic control of charge on the qubit island."
    },
    {
        "anchor": "Synthesis, structure and magnetic properties of Fe@Pt core-shell\n  nanoparticles: Structural and magnetic properties of Fe@Pt core-shell nanostructure prepared\nby a sequential reduction process are reported. Transmission electron\nmicroscopy (TEM) shows nearly spherical particles fitting a lognormal size\ndistribution with $D$$_o$= 3.0 nm and distribution width $\\lambda$$_D$= 0.31.\nIn x-ray diffraction, Bragg lines due to Pt shell only are clearly identified\nwith line-widths yielding crystallite size =3.1 nm. Measurements of\nmagnetization $M$ vs. $T$ (2 K - 350 K) in magnetic fields up to 90 kOe show a\nblocking temperature $T$$_B$ = 13 K below which hysteresis loops are observed\nwith coercivity $H$$_C$ increasing with decreasing $T$ reaching $H$$_C$ = 750\nOe at 2 K. Temperature dependence of the ac susceptibilities at frequencies\n$f$$_m$ = 10 Hz to 5 kHz is measured to determine the change in $T$$_B$ with\n$f$$_m$ using Vogel-Fulcher law. This analysis shows the presence of\nsignificant interparticle interaction, the N\\'{e}el-Brown relaxation frequency\n$f$$_o$ = 5.3 x 10$^{10}$ Hz and anisotropy constant $K$$_a$ =3.6 x10$^6$\nergs/cm$^3$. A fit of the $M$ vs. $H$ data up to $H$ = 90 kOe for $T$ $>$\n$T$$_B$ to the modified Langevin function taking particle size distribution\ninto account yields magnetic moment per particle consistent with the proposed\ncore-shell structure; Fe core of 2.2 nm diameter and Pt shell of 0.4 nm\nthickness.",
        "positive": "Superconductor spintronics: Modeling spin and charge accumulation in\n  out-of-equilibrium NS junctions subjected to Zeeman magnetic fields: We study the spin and charge accumulation in junctions between a\nsuperconductor and a ferromagnet or a normal metal in the presence of a Zeeman\nmagnetic field, when the junction is taken out of equilibrium by applying a\nvoltage bias. We write down the most general form for the spin and charge\ncurrent in such junctions, taking into account all spin-resolved possible\ntunneling processes. We make use of these forms to calculate the spin\naccumulation in NS junctions subjected to a DC bias, and to an AC bias,\nsinusoidal or rectangular. We observe that in the limit of negligeable changes\non the superconducting gap, the NS dynamical conductance is insensitive to spin\nimbalance. Therefore to probe the spin accumulation in the superconductor, one\nneeds to separate the injection and detection point, i. e. the electrical spin\ndetection must be non-local. We address also the effect of the spin\naccumulation induced in the normal leads by driving a spin current and its\neffects on the detection of the spin accumulation in the superconductor.\nFinally, we investigate the out-of-equilibrium spin susceptibility of the SC,\nand we show that it deviates drastically from it's equilibrium value."
    },
    {
        "anchor": "Towards a description of the Kondo effect using time-dependent density\n  functional theory: We demonstrate that the zero-temperature conductance of the Anderson model\ncan be calculated within the Landauer formalism combined with static density\nfunctional theory (DFT). The proposed approximate functional is based on\nfinite-temperature DFT and yields the exact Kohn-Sham potential at the\nparticle-hole symmetric point. Furthermore, in the limit of zero temperature it\ncorrectly exhibits a derivative discontinuity which is shown to be essential to\nreproduce the conductance plateau. On the other hand, at the Kondo temperature\nthe exact Kohn-Sham conductance overestimates the real one by an order of\nmagnitude. To understand the failure of DFT we resort to its time-dependent\nversion and conclude that the suppression of the Kondo resonance with\nincreasing temperature must be attibuted to dynamical exchange-correlation\ncorrections.",
        "positive": "A lossy transmission line as a quantum open system in the standard\n  quantum limit: We systematically investigate how to quantize a transmission line resonator\n(TLR) in a mesoscopic electrical circuits in the presence of the resistance and\nthe conductance of the dielectric media. Developed from the quantum bath based\neffective Hamiltonian method for single mode harmonic oscillator, the approach\nwe presented in this article is a microscopic theory integrating quantum\nfluctuation-dissipation relation. To qualitatively check the condition under\nwhich the TLR can behave as a quantum object we study the classical-quantum\nboundary characterized by the standard quantum limit."
    },
    {
        "anchor": "Modulating dichroism and optical conductivity in bilayer graphene under\n  intense electromagnetic field irradiation: This study explores the impact of a strong perpendicular laser field on the\nelectronic structure and optical conductivity of bilayer graphene. Employing\nthe Floquet-Bloch theorem and a four-band Hamiltonian model, we calculate the\noptical conductivity, unveiling modified optical properties due to the altered\nband structure. We investigate the effects of both circularly and linearly\npolarized dressing fields on the electronic structure and optical conductivity\nin the system. Under linear polarization, we observe a notable anisotropy in\nthe band dispersion and optical conductivity, resulting in linear dichroism. In\nthe case of circular polarization, we anticipate the emergence of induced Berry\ncurvature and circular dichroism, especially close to the dynamical gaps. When\ncircularly polarized light is applied alongside a bias potential, the band\nstructure differs for right-handed and left-handed polarization. In this case,\nthe longitudinal optical conductivity remains the same for both, while the\ntransversal optical conductivity exhibits distinct results. Furthermore, the\ninduced Berry curvature and valley asymmetry introduce the potential for\ngenerating a valley-polarized current, enabling valley-selective pumping and\nleading to circular dichroism.",
        "positive": "Quantum ammeter: We present the theoretical model of the \"quantum ammeter\", a device that is\nable to measure the full counting statistics of an electron current at quantum\ntime scales. It consists of an Ohmic contact, perfectly coupled to chiral\nquantum Hall channels, and of a quantum dot attached to one of the outgoing\nchannels. At energies small compared to its charging energy, the Ohmic contact\nfractionalizes each incoming electron and redistributes it between outgoing\nchannels. By monitoring the resonant tunneling current through the quantum dot,\none gets an access to the moment generator of the current in one of the\nincoming channels at time scales comparable to its correlation time."
    },
    {
        "anchor": "Unraveling the mesoscopic character of quantum dots in nanophotonics: We provide a microscopic theory for semiconductor quantum dots that explains\nthe pronounced deviations from the prevalent point-dipole description that were\nrecently observed in spectroscopic experiments on quantum dots in photonic\nnanostructures. At the microscopic level the deviations originate from\nstructural inhomogeneities generating a large circular quantum current density\nthat flows inside the quantum dot over mesoscopic length scales. The model is\nsupported by the experimental data, where a strong variation of the multipolar\nmoments across the emission spectrum of quantum dots is observed. Our work\nenriches the physical understanding of quantum dots and is of significance for\nthe fields of nanophotonics, quantum photonics, and quantum-information\nscience, where quantum dots are actively employed.",
        "positive": "From Graphene to Bismuth Telluride: Mechanical Exfoliation of Quasi-2D\n  Crystals for Applications in Thermoelectrics and Topological Insulators: Bismuth telluride (Bi2Te3) and its alloys are the best bulk thermoelectric\nmaterials known today. The stacked quasi-two-dimensional (2D) layers of Bi2Te3\nwere also identified as topological insulators. In this paper we describe a\nmethod for graphene-inspired exfoliation of crystalline bismuth telluride films\nwith a thickness of a few atoms. The atomically thin films were suspended\nacross trenches in Si/SiO2 substrates, and subjected to detail\ncharacterization. The presence of the van der Waals gaps allowed us to\ndisassemble Bi2Te3 crystal into its quintuple building blocks - five\nmono-atomic sheets consisting of Te(1)-Bi-Te(2)-Bi-Te(1). By altering the\nthickness and sequence of atomic planes we were able to create designer\nnon-stoichiometric quasi-2D crystalline films, change their composition and\ndoping, as well as other properties. The exfoliated quintuples and ultra-thin\nfilms have low thermal conductivity, high electrical conductivity and enhanced\nthermoelectric properties. The obtained results pave the way for producing\nstacks of crystalline bismuth telluride quantum wells with the strong spatial\nconfinement of charge carriers and acoustic phonons for thermoelectric devices.\nThe developed technology for producing free-standing quasi-2D layers of\nTe(1)-Bi-Te(2)-Bi-Te(1) creates an impetus for investigation of the topological\ninsulators and their possible practical applications."
    },
    {
        "anchor": "Coulomb drag in graphene single layers separated by a thin spacer: Motivated by very recent studies of Coulomb drag in grahene-BN-graphene\nsystem we develop a theory of Coulomb drag for the Fermi liquid regime, for the\ncase when the ratio of spacer thickness $d$ to the Fermi wavelength of\nelectrons is arbitrary. The concentration ($n$) and thickness dependence of the\ndrag resistivity is changed from $n^{-3}d^{-4}$ for the thick spacer to\n$n^{-1}|\\ln{(nd^2)}|$ for the thin one.",
        "positive": "Hard wall edge confinement in 2D topological insulators and the energy\n  of the Dirac Point: In 2D topological insulators (TIs) based on semiconductor quantum wells such\nas HgTe/CdTe or InAs/GaSb/AlSb, spin polarized edge states have been predicted\nwith a massless Dirac like dispersion. In a hard wall treatment based on the 4\nx 4 BHZ Hamiltonian and open boundary conditions (OBCs), the wave function is\nweakly confined near the edge, with which it makes no contact. In contrast,\nstandard boundary conditions for the wave function and its derivative (SBCs)\nlead to strong confinement with a peak amplitude at the edge. Unfortunately,\nweak confinement exhibits unphysical behavior related to a spurious gap\nsolution that is included in the OBC wave function. This is confirmed by the\ngap solutions of the parent multiband Hamiltonian from which the smaller\nHamiltonian is derived, which exhibit physical behavior and do not satisfy\nOBCs. Unlike OBCs or other approaches based on phenomenological boundary\nconditions, SBCs treat the wall explicitly. Using a basis of empty crystal free\nelectron states for the vacuum with the same symmetry as the TI states, it is\nshown that a large wall band gap overlapping that of the TI can only be\nachieved by including a thin passivation layer. For passivation materials such\nas silicon dioxide where the mid gap energy is nearly degenerate with that of\nthe TI, the Dirac point is very close to mid gap and virtually independent of\nthe TI band asymmetry. The treatment also demonstrates that a significant shift\nof the dispersion may be introduced by interface band mixing. The shift is\nlargest at the Dirac point and decreases monotonically with edge state wave\nvector, vanishing when the edge states merge with the bulk band edges."
    },
    {
        "anchor": "Weak localisation, hole-hole interactions and the \"metal\"-insulator\n  transition in two dimensions: A detailed investigation of the metallic behaviour in high quality\nGaAs-AlGaAs two dimensional hole systems reveals the presence of quantum\ncorrections to the resistivity at low temperatures. Despite the low density\n($r_{s}>10$) and high quality of these systems, both weak localisation\n(observed via negative magnetoresistance) and weak hole-hole interactions\n(giving a correction to the Hall constant) are present in the so-called\nmetallic phase where the resistivity decreases with decreasing temperature. The\nresults suggest that even at high $r_{s}$ there is no metallic phase at T=0 in\ntwo dimensions.",
        "positive": "Experimental review on Majorana zero-modes in hybrid nanowires: As the condensed matter analog of Majorana fermion, the Majorana zero-mode is\nwell known as a building block of fault-tolerant topological quantum computing.\nThis review focuses on the recent progress of Majorana experiments, especially\nexperiments about semiconductor-superconductor hybrid devices. We first sketch\nMajorana zero-mode formation from a bottom-up view, which is more suitable for\nbeginners and experimentalists. Then, we survey the status of zero-energy state\nsignatures reported recently, from zero-energy conductance peaks, the\noscillations, the quantization, and the interactions with extra degrees of\nfreedom. We also give prospects of future experiments for advancing\none-dimensional semiconductor nanowire-superconductor hybrid materials and\ndevices."
    },
    {
        "anchor": "Entanglement detection from conductance measurements in carbon nanotube\n  Cooper pair splitters: Spin-orbit interaction provides a spin filtering effect in carbon nanotube\nbased Cooper pair splitters that allows us to determine spin correlators\ndirectly from current measurements. The spin filtering axes are tunable by a\nglobal external magnetic field. By a bending of the nanotube the filtering axes\non both sides of the Cooper pair splitter become sufficiently different that a\ntest of entanglement of the injected Cooper pairs through the Bell inequality\ncan be implemented. This implementation does not require noise measurements,\nsupports imperfect splitting efficiency and disorder, and does not demand a\nfull knowledge of the spin-orbit strength. Using a microscopic calculation we\ndemonstrate that entanglement detection by violation of the Bell inequality is\nwithin the reach of current experimental setups.",
        "positive": "Tunneling through molecules and quantum dots: master-equation approaches: An important class of approaches to the description of electronic transport\nthrough molecules and quantum dots is based on the master equation. We discuss\nvarious formalisms for deriving a master equation and their interrelations. It\nis shown that the master equations derived by Wangsness, Bloch, and Redfield\nand by Koenig et al. are equivalent. The roles of the large-reservoir and\nMarkov approximations are clarified. The Markov approximation is traced back to\nnonzero bias voltage and temperature, whereas interactions and the\ncorresponding rapid relaxation in the leads are shown to be irrelevant for the\ntransport under certain conditions. It is explained why the T-matrix formalism\ngives incomplete results except for diagonal density operators and to second\norder in the tunneling amplitudes. The time-convolutionless master equation is\nadapted to tunneling problems and a diagrammatic scheme for generating\narbitrary orders in the tunneling amplitudes is developed."
    },
    {
        "anchor": "Site-dependent conduction channel transmission in atomic-scale\n  superconducting junctions: Using scanning tunneling microscopy, we reproducibly obtained electrical\nconductance spectra of superconductor- superconductor atomic point contacts\nformed on various atomic sites of the substrate. From the analysis of the\nsubharmonic features due to the multiple Andreev reflection, spatial\ndistributions of the number of the conduction channels and their transmission\nprobabilities were obtained. It is found that the number of channels and the\ntransmission probabilities strongly depend on an atomic site where the contact\nis formed. We also revealed how the conduction channels and their transmission\nprobability evolve from the tunneling to contact regimes. The Josephson current\nalso exhibits the atomic site dependence, which is explained by the\nsite-dependent transmission probabilities. Our results demonstrate a crucial\nrole of the atomic geometry in the conduction channels of the ultimately\nconfined conductor for the first time experimentally.",
        "positive": "High quality electrostatically defined hall bars in monolayer graphene: Realizing graphene's promise as an atomically thin and tunable platform for\nfundamental studies and future applications in quantum transport requires the\nability to electrostatically define the geometry of the structure and control\nthe carrier concentration, without compromising the quality of the system.\nHere, we demonstrate the working principle of a new generation of high quality\ngate defined graphene samples, where the challenge of doing so in a gapless\nsemiconductor is overcome by using the $\\nu=0$ insulating state, which emerges\nat modest applied magnetic fields. In order to verify that the quality of our\ndevices is not compromised by the presence of multiple gates we compare the\nelectronic transport response of different sample geometries, paying close\nattention to fragile quantum states, such as the fractional quantum Hall (FQH)\nstates, that are highly susceptible to disorder. The ability to define local\ndepletion regions without compromising device quality establishes a new\napproach towards structuring graphene-based quantum transport devices."
    },
    {
        "anchor": "Entangling a nanomechanical resonator and a superconducting microwave\n  cavity: We propose a scheme able to entangle at the steady state a nanomechanical\nresonator with a microwave cavity mode of a driven superconducting coplanar\nwaveguide. The nanomechanical resonator is capacitively coupled with the\ncentral conductor of the waveguide and stationary entanglement is achievable up\nto temperatures of tens of milliKelvin.",
        "positive": "Non-equilibrium nuclear spin distribution function in quantum dots\n  subject to periodic pulses: Electron spin dephasing in a singly charged semiconductor quantum dot can\npartially be suppressed by periodic laser pulsing. We propose a semi-classical\napproach describing the decoherence of the electron spin polarization governed\nby the hyperfine interaction with the nuclear spins as well as the\nprobabilistic nature of the photon absorption. We use the steady-state Floquet\ncondition to analytically derive two subclasses of resonance conditions\nexcellently predicting the peak locations in the part of the Overhauser field\ndistribution which is projected in the direction of the external magnetic\nfield. As a consequence of the periodic pulsing, a non-equilibrium distribution\ndevelops as a function of time. The numerical simulation of the coupled\ndynamics reveals the influence of the hyperfine coupling constant distribution\nonto the evolution of the electron spin polarisation before the next laser\npulse. Experimental indications are provided for both subclasses of resonance\nconditions."
    },
    {
        "anchor": "Strong interminivalley scattering in twisted bilayer graphene revealed\n  by high-temperature magnetooscillations: Twisted bilayer graphene (TBG) provides an example of a system in which the\ninterplay of interlayer interactions and superlattice structure impacts\nelectron transport in a variety of non-trivial ways and gives rise to a\nplethora of interesting effects. Understanding the mechanisms of electron\nscattering in TBG has, however, proven challenging, raising many questions\nabout the origins of resistivity in this system. Here we show that TBG exhibits\nhigh-temperature magnetooscillations originating from the scattering of charge\ncarriers between TBG minivalleys. The amplitude of these oscillations reveals\nthat interminivalley scattering is strong, and its characteristic time scale is\ncomparable to that of its intraminivalley counterpart. Furthermore, by\nexploring the temperature dependence of these oscillations, we estimate the\nelectron-electron collision rate in TBG and find that it exceeds that of\nmonolayer graphene. Our study demonstrates the consequences of the relatively\nsmall size of the superlattice Brillouin zone and Fermi velocity reduction on\nlateral transport in TBG.",
        "positive": "Inverted random nanopyramids patterning for crystalline silicon\n  photovoltaics: We demonstrate a nanopatterning technique for silicon photovoltaics, which\noptically outperforms conventional micron-scale random pyramids, while\ndecreasing by a factor of ten the quantity of silicon lost during the texturing\nprocess. We combine hole-mask colloidal lithography, a bottom-up\nnanolithography technique, with reactive ion etching to define nanopyramids at\nthe surface of a silicon wafer. Thanks to the self-organised aspect of the\ntechnique, the beads are randomly distributed, however keeping a interbead\ndistance of the order of their diameter. We tune the nanopattern feature size\nto maximize the absorption in the crystalline silicon by exploiting both\nanti-reflection and light trapping. When optimized, the nanopyramids lead to a\nhigher absorption in the crystalline silicon than the conventional micron-scale\nrandom pyramids in the visible and near the band edge, with a superior\nrobustness to variations of the angle of the incident light. As the\nnanopatterning technique presented here is simple, we expect that it could be\nreadily integrated into the crystalline silicon solar cell fabrication\nprocessing."
    },
    {
        "anchor": "Local Gating of an Ir(111) Surface Resonance by Graphene Islands: The influence of graphene islands on the electronic structure of the Ir(111)\nsurface is investigated. Scanning tunneling spectroscopy (STS) indicates the\npresence of a two-dimensional electron gas with a binding energy of -160meV and\nan effective mass of -0.18m_e underneath single-layer graphene on the Ir(111)\nsurface. Density functional calculations reveal that the STS features are\npredominantly due to a holelike surface resonance of the Ir(111) substrate.\nNanometer-sized graphene islands act as local gates, which shift and confine\nthe surface resonance.",
        "positive": "Quantum Hall Mach-Zehnder interferometer at fractional filling factors: We use a Mach-Zehnder quantum Hall interferometer of a novel design to\ninvestigate the interference effects at fractional filling factors. Our device\nbrings together the advantages of usual Mach-Zehnder and Fabry-Perot quantum\nHall interferometers. It realizes the simplest-for-analysis Mach-Zehnder\ninterference scheme, free from Coulomb blockade effects. By contrast to the\nstandard Mach-Zehnder realization, our device does not contain an etched region\ninside the interference loop. For the first time for Mach-Zehnder interference\nscheme, the device demonstrates interference oscillations with\n$\\Phi^*=e/e^*\\Phi_0=\\Phi_0/\\nu$ periodicity at fractional filling factor 1/3.\nThis result indicates that we observe clear evidence for fractionally charged\nquasiparticles from simple Aharonov-Bohm interference."
    },
    {
        "anchor": "Density of states at disorder-induced phase transitions in a\n  multichannel Majorana wire: An $N$-channel spinless p-wave superconducting wire is known to go through a\nseries of $N$ topological phase transitions upon increasing the disorder\nstrength. Here, we show that at each of those transitions the density of states\nshows a Dyson singularity $\\nu(\\varepsilon) \\propto\n\\varepsilon^{-1}|\\ln\\varepsilon|^{-3} $, whereas $\\nu(\\varepsilon) \\propto\n\\varepsilon^{|\\alpha|-1}$ has a power-law singularity for small energies\n$\\varepsilon$ away from the critical points. Using the concept of\n\"superuniversality\" [Gruzberg, Read, and Vishveshwara, Phys. Rev. B 71, 245124\n(2005)], we are able to relate the exponent $\\alpha$ to the wire's transport\nproperties at zero energy and, hence, to the mean free path $l$ and the\nsuperconducting coherence length $\\xi$.",
        "positive": "Floquet-Drude conductivity: This letter presents a generalization of the Drude conductivity for systems\nwhich are exposed to periodic driving. The probe bias is treated perturbatively\nby using the Kubo formula, whereas the external driving is included\nnon-perturbatively using the Floquet theory. Using a new type of four-times\nGreen's functions disorder is approached diagrammatically, yielding a fully\nanalytical expression for the Floquet-Drude conductivity. Furthermore, the\nFloquet Fermi's golden rule is generalized to $tt'$-Floquet states, connecting\nthe Floquet-Dyson series with scattering theory for Floquet states. Our\nformalism allows for a direct application to numerous systems e.g. graphene or\nspin-orbit systems."
    },
    {
        "anchor": "Nonadiabatic Josephson current pumping by microwave irradiation: Irradiating a Josephson junction with microwaves can operate not only on the\namplitude but also on the phase of the Josephson current. This requires\nbreaking time inversion symmetry, which is achieved by introducing a phase\nlapse between the microwave components acting on the two{\\dag} sides of the\njunction. General symmetry arguments and the solution of a specific single\nlevel quantum dot model show that this induces chirality in the Cooper pair\ndynamics, due to the topology of the Andreev bound state wavefunction. Another\nessential condition is to break electron-hole symmetry within the junction. A\nshift of the current-phase relation is obtained, which is controllable in sign\nand amplitude with the microwave phase and an electrostatic gate, thus\nproducing a \"chiral\" Josephson transistor. The dot model is solved in the\ninfinite gap limit by Floquet theory and in the general case with Keldysh\nnonequilibrium Green's functions. The chiral current is nonadiabatic: it is\nextremal and changes sign close to resonant chiral transitions between the\nAndreev bound states.",
        "positive": "Electrical control of uniformity in quantum dot devices: Highly uniform quantum systems are essential for the practical implementation\nof scalable quantum processors. While quantum dot spin qubits based on\nsemiconductor technology are a promising platform for large-scale quantum\ncomputing, their small size makes them particularly sensitive to their local\nenvironment. Here, we present a method to electrically obtain a high degree of\nuniformity in the intrinsic potential landscape using hysteretic shifts of the\ngate voltage characteristics. We demonstrate the tuning of pinch-off voltages\nin quantum dot devices over hundreds of millivolts that then remain stable at\nleast for hours. Applying our method, we homogenize the pinch-off voltages of\nthe plunger gates in a linear array for four quantum dots reducing the spread\nin pinch-off voltage by one order of magnitude. This work provides a new tool\nfor the tuning of quantum dot devices and offers new perspectives for the\nimplementation of scalable spin qubit arrays."
    },
    {
        "anchor": "A Josephson Junction Microscope for Low-frequency Fluctuators: The high-Q harmonic oscillator mode of a Josephson junction can be used as a\nnovel probe of spurious two-level systems (TLSs) inside the amorphous oxide\ntunnel barriers of the junction. In particular, we show that spectroscopic\ntransmission measurements of the junction resonator mode can reveal how the\ncoupling magnitude between the junction and the TLSs varies with an external\nmagnetic field applied in the plane of the tunnel barrier. The proposed\nexperiments offer the possibility of clearly resolving the underlying coupling\nmechanism for these spurious TLSs, an important decoherence source limiting the\nquality of superconducting quantum devices.",
        "positive": "Single-Molecule Device Prototypes for Protein-Based Nanoelectronics:\n  Negative Differential Resistance and Current Rectification in Oligopeptides: We investigate electrical conduction through individual oligopeptide\nmolecules thiol-bonded between gold nanocontacts using ab initio and\nsemi-empirical techniques. Our theory explains for the first time these\nmolecules' experimentally observed current-voltage characteristics, including\nboth the magnitude and rectification of the current, and uses no adjustable\nparameters. We identify the mechanism of the observed current rectification,\nand predict that it will result in negative differential resistance at moderate\nbiases. Our findings open the way to the realization of protein-based\nnanoelectronic devices."
    },
    {
        "anchor": "Non-exponential relaxations in disordered conductors: We show that, in low dimensional conductors, the quasiparticle decay and the\nrelaxation of the phase are not exponential processes. In quasi-one dimension,\nthey scale as $e^{- (t/\\tau_N)^{3/2}}$ where the characteristic time\n$\\tau_{in}$, identical for both processes, is a power $T^{2/3}$ of the\ntemperature. This result implies a distribution of relaxation times.",
        "positive": "On the remote coherence of polariton condensates in 1D microcavities: a\n  photoluminescence study: In this manuscript we will gather clear experimental evidences of remote\ncoherence between two polariton condensate droplets that have never overlapped\nin real space and discuss how these interferences in momentum space can be used\nto estimate the critical temperature for the BEC like transition."
    },
    {
        "anchor": "Multiple Edge Partition Functions For Fractional Quantum Hall States: We consider the multiple edge states of the Laughlin state and the Pfaffian\nstate. These edge states are globally constrained through the operator algebra\nof conformal field theory in the bulk. We analyze these constraints by\nintroducing an expression of quantum hall state by the chiral vertex operators\nand obtain the multiple edge partition functions by using the Verlinde formula.",
        "positive": "Molecular orbital calculations of two-electron states for P donor\n  solid-state spin qubits: We theoretically study the Hilbert space structure of two neighbouring P\ndonor electrons in silicon-based quantum computer architectures. To use\nelectron spins as qubits, a crucial condition is the isolation of the electron\nspins from their environment, including the electronic orbital degrees of\nfreedom. We provide detailed electronic structure calculations of both the\nsingle donor electron wave function and the two-electron pair wave function. We\nadopted a molecular orbital method for the two-electron problem, forming a\nbasis with the calculated single donor electron orbitals. Our two-electron\nbasis contains many singlet and triplet orbital excited states, in addition to\nthe two simple ground state singlet and triplet orbitals usually used in the\nHeitler-London approximation to describe the two-electron donor pair wave\nfunction. We determined the excitation spectrum of the two-donor system, and\nstudy its dependence on strain, lattice position and inter donor separation.\nThis allows us to determine how isolated the ground state singlet and triplet\norbitals are from the rest of the excited state Hilbert space. In addition to\ncalculating the energy spectrum, we are also able to evaluate the exchange\ncoupling between the two donor electrons, and the double occupancy probability\nthat both electrons will reside on the same P donor. These two quantities are\nvery important for logical operations in solid-state quantum computing devices,\nas a large exchange coupling achieves faster gating times, whilst the magnitude\nof the double occupancy probability can affect the error rate."
    },
    {
        "anchor": "Nanoscopic interferometer model for spin resonance in current noise: We study a model for the observed phenomenon of electron spin resonance (ESR)\nat the Zeeman frequency as seen by a scanning tunneling microscope (STM) via\nits current noise. The model for this ESR-STM phenomenon allows the STM current\nto flow in two arms of a nanoscopic interferometer, one arm has direct\ntunneling from the tip to the substrate while the second arm has tunneling\nthrough two spin states. We evaluate analytically the noise spectrum for\nnon-polarized leads, as relevant to the experimental setup. We show that\nspin-orbit interactions allow for an interference of two tunneling paths\nresulting in a resonance effect.",
        "positive": "Current-driven domain wall motion with spin Hall effect: Reduction of\n  threshold current density: We theoretically study the current-driven domain wall motion in the presence\nof both the spin Hall effect and an extrinsic pinning potential. The spin Hall\neffect mainly affects the damping ratio of the domain wall precession in the\npinning potential. When the pinning potential is not too strong, this results\nin a significant reduction of a threshold current density for the depinning of\na domain wall with certain polarity. We also propose one way to distinguish the\nspin Hall effect induced spin-transfer torque from the one induced by the\nRashba spin-orbit coupling experimentally."
    },
    {
        "anchor": "Dielectric Confinement Enables Molecular Coupling in Stacked Colloidal\n  Nanoplatelets: We show theoretically that carriers confined in semiconductor colloidal\nnanoplatelets (NPLs) sense the presence of neighbor, cofacially stacked NPLs in\ntheir energy spectrum. When approaching identical NPLs, the otherwise\ndegenerate energy levels redshift and split, forming (for large stacks)\nminibands of several meV width. Unlike in epitaxial structures, the molecular\nbehavior does not result from quantum tunneling but from changes in the\ndielectric confinement. The associated excitonic absorption spectrum shows a\nrich structure of bright and dark states, whose optical activity and\nmultiplicity can be understood from reflection symmetry and Coulomb tunneling.\nWe predict spectroscopic signatures which should confirm the formation of\nmolecular states, whose practical realization would pave the way to the\ndevelopment of nanocrystal chemistry based on NPLs.",
        "positive": "Kondo correlations formation and the local magnetic moment dynamics in\n  the Anderson model: We investigated the typical time scales of the Kondo correlations formation\nfor the single-state Anderson model, when coupling to the reservoir is switched\non at the initial time moment. The influence of the Kondo effect appearance on\nthe system non-stationary characteristics was analyzed and discussed."
    },
    {
        "anchor": "Spin Polarization Dependence of the Coulomb Drag at Large $r_{s}$: We find that the temperature dependence of the drag resistivity ($\\rho_{D}$)\nbetween two dilute two-dimensional hole systems exhibits an unusual dependence\nupon spin polarization. Near the apparent metal-insulator transition, the\ntemperature dependence of the drag, given by $T^{\\alpha}$, weakens with the\napplication of a parallel magnetic field ($B_{||}$), with $\\alpha$ saturating\nat half its zero field value for $B_{||} > B^{*}$, where $B^{*}$ is the\npolarization field. Furthermore, we find that $\\alpha$ is roughly 2 at the\nparallel field induced metal-insulator transition, and that the temperature\ndependence of $\\rho_{D}/T^{2}$ at different $B_{||}$ looks strikingly similar\nto that found in the single layer resistivity. In contrast, at higher\ndensities, far from the zero field transition, the temperature dependence of\nthe drag is roughly independent of spin polarization, with $\\alpha$ remaining\nclose to 2, as expected from a simple Fermi liquid picture.",
        "positive": "Electrothermal Actuation of NEMS Resonators: Modeling and Experimental\n  Validation: We study the electrothermal actuation of nanomechanical motion using a\ncombination of numerical simulations and analytical solutions. The\nnanoelectrothermal actuator structure is a u-shaped gold nanoresistor that is\npatterned on the anchor of a doubly-clamped nanomechanical beam or a\nmicrocantilever resonator. This design has been used in recent experiments\nsuccessfully. In our finite-element analysis (FEA) based model, our input is an\nac current; we first calculate the temperature oscillations due to Joule\nheating using Ohm's Law and the heat equation; we then determine the thermally\ninduced bending moment and the displacement profile of the beam by coupling the\ntemperature field to Euler-Bernoulli beam theory with tension. Our model\nefficiently combines transient and frequency-domain analyses: we compute the\ntemperature field using a transient approach and then impose this temperature\nfield as a harmonic perturbation for determining the mechanical response in the\nfrequency domain. This unique modeling method offers lower computational\ncomplexity and improved accuracy, and is faster than a fully transient FEA\napproach. Our dynamical model computes the temperature and displacement fields\nin time domain over a broad range of actuation frequencies and amplitudes. We\nvalidate the numerical results by directly comparing them with experimentally\nmeasured displacement amplitudes of NEMS beams around their eigenmodes in\nvacuum. Our model predicts a thermal time constant of 1.9 ns in vacuum for our\nparticular structures, indicating that electrothermal actuation is efficient up\nto ~80 MHz. We also investigate the thermal response of the actuator when\nimmersed in a variety of fluids."
    },
    {
        "anchor": "Long-range permeation of wave function and superficial surface state due\n  to strong quantum size effects in topological Bi/BiSb heterojunctions: The quantum size effect has a significant impact on electrons, such that it\ncan even change their topologically protected properties. An example of this\nphenomenon is the gap opening in the topologically protected gapless surface\nstate in finite-thickness topological-insulator films. However, much is not\nknown about the quantum size effect in topological heterojunctions. In this\nstudy, by calculating the single-particle spectrum of Bi/Bi$_{1-x}$Sb$_{x}$\nbased on the well-known Liu-Allen model, we found that the strong quantum size\neffect in topological heterojunctions yields an unexpected band alignment. The\nwave functions permeate each other through the attached materials, and this\noccurs even in 80-nm-thick heterojunctions. Furthermore, we theoretically found\nthat one of the two major spectra obtained from the Bi surface does not\nrepresent the true surface state of Bi. This finding may overturn the previous\nunderstanding of the topological surface state of Bi.",
        "positive": "All-electric spin transistor based on a side-gate-modulated\n  two-dimensional topological insulator: We propose and investigate a spin transistor device consisting of two\nferromagnetic leads connected by a two-dimensional topological insulator as the\nchannel material. It exploits the unique features of the topological\nspin-helical edge states, such that the injected carriers with a non-collinear\nspin-direction would travel through both edges and show interference effect.\nThe conductance of the device can be controlled in a simple and allelectric\nmanner by a side-gate voltage, which effectively rotates the spin-polarization\nof the carrier. At low voltages, the rotation angle is linear in the gate\nvoltage, and the device can function as a good spin-polarization rotator by\nreplacing the drain electrode with a paramagnetic material."
    },
    {
        "anchor": "Orthogonality catastrophe in a composite fermion liquid: We discuss the emergence of an orthogonality catastrophe in the response of a\ncomposite fermion liquid as the filling factor \\nu approaches 1/2m, where\nm=1,2,3.... A tunneling experiment is proposed in which dramatic changes in the\nI-V characteristic should be observable as \\nu is varied. Explicit I-V\ncharacteristics calculated within the so-called Modified Random Phase\nApproximation, are provided for \\nu=1/3 -> \\nu=1/2.",
        "positive": "Theory of Quantum Work in Metallic Grains: We generalize Anderson's orthogonality determinant formula to describe the\nstatistics of work performed on generic disordered, non-interacting fermionic\nnanograins during quantum quenches. The energy absorbed increases linearly with\ntime, while its variance exhibits a superdiffusive behavior due to Pauli's\nexclusion principle. The probability of adiabatic evolution decays as a\nstretched exponential. In slowly driven systems, work statistics exhibits\nuniversal features, and can be understood in terms of fermion diffusion in\nenergy space, generated by Landau-Zener transitions. This diffusion is very\nwell captured by a Markovian symmetrical exclusion process, with the diffusion\nconstant identified as the energy absorption rate. The energy absorption rate\nshows an anomalous frequency dependence at small energies, reflecting the\nsymmetry class of the underlying Hamiltonian. Our predictions can be\nexperimentally verified by calorimetric measurements performed on nanoscale\ncircuits."
    },
    {
        "anchor": "New explanation of Raman peak redshift in nanoparticles: In this letter, we propose a new model that explains the Raman peak downshift\nobserved in nanoparticles with respect to bulk materials. The proposed model\ntakes into account discreteness of the vibrational spectra of nanoparticles.\nFor crystals with a cubic lattice (Diamond, Silicon, Germanium) we give a\nrelation between the displacement of Raman peak position and the size of\nnanoparticles. The proposed model does not include any uncertain parameters,\nunlike the conventionally used phonon confinement model (PCM), and can be\nemployed for unambiguous nanoparticles size estimation.",
        "positive": "Quantum electrodynamics description of localized surface plasmons at a\n  metal nanosphere: A canonical quantization scheme for localized surface plasmons (LSPs) in a\nmetal nanosphere is presented based on a microscopic model composed of\nelectromagnetic fields, oscillators that describe plasmons, and a reservoir\nthat describes excitations other than plasmons. The eigenmodes of this fully\nquantum electrodynamic theory show a spectrum that includes radiative\ndepolarization and broadening, including redshifting from the quasi-static LSP\nmodes, with increasing particle size. These spectral profiles correctly match\nthose obtained with exact classical electrodynamics (Mie theory). The present\nscheme provides the electric fields per plasmon in both near- and far-field\nregions whereby its utility in the fields of quantum plasmonics and nano-optics\nis demonstrated."
    },
    {
        "anchor": "Slant-gap plasmonic nanoantenna for optical chirality enhancement: We present a new design of plasmonic nanoantenna with a slant gap for optical\nchirality engineering. At resonance, the slant gap provides highly enhanced\nelectric field parallel to external magnetic field with a phase delay of 90\ndegree, resulting in enhanced optical chirality. We show by numerical\nsimulations that upon linearly polarized excitation our achiral nanoantenna can\ngenerate near field with enhanced optical chirality that can be tuned by the\nslant angle and resonance condition. Our design can be easily realized and may\nfind applications in circular dichroism enhancement.",
        "positive": "Fast tunnel rates in Si/SiGe one-electron single and double quantum dots: We report the fabrication and measurement of one-electron single and double\nquantum dots with fast tunnel rates in a Si/SiGe heterostructure. Achieving\nfast tunnel rates in few-electron dots can be challenging, in part due to the\nlarge electron effective mass in Si. Using charge sensing, we identify\nsignatures of tunnel rates in and out of the dot that are fast or slow compared\nto the measurement rate. Such signatures provide a means to calibrate the\nabsolute electron number and verify single electron occupation. Pulsed gate\nvoltage measurements are used to validate the approach."
    },
    {
        "anchor": "Theory of the STM detection of Wigner molecules in spin incoherent CNTs: The linear conductance of a carbon nanotube quantum dot in the Wigner\nmolecule regime, coupled to two scanning tunnel microscope tips is inspected.\nConsidering the high temperature regime, the nanotube quantum dot is described\nby means of the spin-incoherent Luttinger liquid picture. The linear\nconductance exhibits spatial oscillations induced by the presence of the\ncorrelated, molecular electron state. A power-law scaling of the electron\ndensity and of the conductance as a function of the interaction parameter are\nfound. They confirm local transport as a sensitive tool to investigate the\nWigner molecule. The double-tip setup allows to explore different transport\nregimes with different shapes of the spatial modulation, all bringing\ninformation about the Wigner molecule.",
        "positive": "Thermal Dissipation and Variability in Electrical Breakdown of Carbon\n  Nanotube Devices: We study high-field electrical breakdown and heat dissipation from carbon\nnanotube (CNT) devices on SiO2 substrates. The thermal \"footprint\" of a CNT\ncaused by van der Waals interactions with the substrate is revealed through\nmolecular dynamics (MD) simulations. Experiments and modeling find the\nCNT-substrate thermal coupling scales proportionally to CNT diameter and\ninversely with SiO2 surface roughness (~d/{\\Delta}). Comparison of diffuse\nmismatch modeling (DMM) and data reveals the upper limit of thermal coupling\n~0.4 W/K/m per unit length at room temperature, and ~0.7 W/K/m at 600 C for the\nlargest diameter (3-4 nm) CNTs. We also find semiconducting CNTs can break down\nprematurely, and display more breakdown variability due to dynamic shifts in\nthreshold voltage, which metallic CNTs are immune to; this poses a fundamental\nchallenge for selective electrical breakdowns in CNT electronics."
    },
    {
        "anchor": "Realizable spin models and entanglement dynamics in superconducting flux\n  qubit systems: Realizable spin models are investigated in a two superconducting flux qubit\nsystem. It is shown that a specific adjustment of system parameters in the two\nflux qubit system makes it possible to realize an artificial two-spin system\nthat cannot be found naturally. For the artificial two-spin systems, time\nevolution of a prepared quantum state is discussed to quantify quantum\nentanglement dynamics. The concurrence and fidelity as a function of time are\nshown to reveal a characteristic entanglement dynamics of the artificial spin\nsystems. It is found that the unentangled input state can evolute to be a\nmaximally entangled output state periodically due to the exchange interactions\ninduced by two-qubit flipping tunneling processes while single-qubit flipping\ntunneling processes plays a role of magnetic fields for the artificial spins.",
        "positive": "Sound-driven single-electron transfer in a circuit of coupled quantum\n  rails: Surface acoustic waves (SAWs) strongly modulate the shallow electric\npotential in piezoelectric materials. In semiconductor heterostructures such as\nGaAs/AlGaAs, SAWs can thus be employed to transfer individual electrons between\ndistant quantum dots. This transfer mechanism makes SAW technologies a\npromising candidate to convey quantum information through a circuit of quantum\nlogic gates. Here we present two essential building blocks of such a SAW-driven\nquantum circuit. First, we implement a directional coupler allowing to\npartition a flying electron arbitrarily into two paths of transportation.\nSecond, we demonstrate a triggered single-electron source enabling\nsynchronisation of the SAW-driven sending process. Exceeding a single-shot\ntransfer efficiency of 99 %, we show that a SAW-driven integrated circuit is\nfeasible with single electrons on a large scale. Our results pave the way to\nperform quantum logic operations with flying electron qubits."
    },
    {
        "anchor": "Magnetic states in multiply-connected flat nano-elements: Flat magnetic nano-elements are an essential component of current and future\nspintronic devices. By shaping an element it is possible to select and\nstabilize chosen metastable magnetic states, control its magnetization\ndynamics. Here, using a recent significant development in mathematics of\nconformal mapping, complex variable based approach to the description of\nmagnetic states in planar nano-elements is extended to the case when elements\nare multiply-connected (that is, contain holes or magnetic anti-dots). We show\nthat presence of holes implies a certain restriction on the set of magnetic\nstates of nano-element.",
        "positive": "Dynamics of an Exciton-phonon Triangle under Photoirradiation: Herein, the dynamics of excitons coupled with optical phonons in a triangular\nsystem is numerically studied. By representing the excitons by quasi-spin\nstates, the similarity between the chiral spin states and the exciton chiral\nstates is discussed. In particular, the optical control of excitons is\ndiscussed, where photoirradiation causes the switching of the exciton states on\nthe ultrafast time scale by Raman scattering. A phase diagram is obtained based\non the ground-state properties of the system determined by the magnitudes of\nthe exciton-phonon interactions and exciton transfer energy. By varying the\nfrequency and/or intensity of light, a transition between exciton-phonon\ncomposite states is induced, which suggests the possibility of the coherent\ncontrol of the chiral properties of excitonic systems via phonon excitation."
    },
    {
        "anchor": "Adiabatic charge and spin pumping through quantum dots with\n  ferromagnetic leads: We study adiabatic pumping of electrons through quantum dots attached to\nferromagnetic leads. Hereby we make use of a real-time diagrammatic technique\nin the adiabatic limit that takes into account strong Coulomb interaction in\nthe dot. We analyze the degree of spin polarization of electrons pumped from a\nferromagnet through the dot to a nonmagnetic lead (N-dot-F) as well as the\ndependence of the pumped charge on the relative leads' magnetization\norientations for a spin-valve (F-dot-F) structure. For the former case, we find\nthat, depending on the relative coupling strength to the leads, spin and charge\ncan, on average, be pumped in opposite directions. For the latter case, we find\nan angular dependence of the pumped charge, that becomes more and more\nanharmonic for large spin polarization in the leads.",
        "positive": "Influence of Nuclear Quadrupole Moments on Electron Spin Coherence in\n  Semiconductor Quantum Dots: We theoretically investigate the influence of the fluctuating Overhauser\nfield on the spin of an electron confined to a quantum dot (QD). The\nfluctuations arise from nuclear angular momentum being exchanged between\ndifferent nuclei via the nuclear magnetic dipole coupling. We focus on the role\nof the nuclear electric quadrupole moments (QPMs), which generally cause a\nreduction in internuclear spin transfer efficiency in the presence of electric\nfield gradients. The effects on the electron spin coherence time are studied by\nmodeling an electron spin echo experiment. We find that the QPMs cause an\nincrease in the electron spin coherence time and that an inhomogeneous\ndistribution of the quadrupolar shift, where different nuclei have different\nshifts in energy, causes an even larger increase in the electron coherence time\nthan a homogeneous distribution. Furthermore, a partial polarization of the\nnuclear spin ensemble amplifies the effect of the inhomogeneous quadrupolar\nshifts, causing an additional increase in electron coherence time, and provides\nan alternative to the experimentally challenging suggestion of full dynamic\nnuclear spin polarization."
    },
    {
        "anchor": "Josephson-Coulomb drag effect between graphene and LaAlO3/SrTiO3\n  interfacial superconductor: Coulomb drag refers to the phenomenon that a charge current in one electronic\ncircuit induces a responsive current in a neighboring circuit solely through\nCoulomb interactions. For conventional interactions between fermionic particles\nsuch as electrons, the as-induced drag current in the passive layer is orders\nof magnitude weaker than the active current due to strong dielectric screening\neffect between the two. Here we propose a 'super' Coulomb drag effect between\nan active normal conductor and a passive superconductor of Josephson junction\narrays, whereby the passive current can greatly exceed the active. The drag\nforce originates from the interactions between the substantially enhanced\ndynamical quantum fluctuations of the superconducting phases in the passive\nlayer and the normal electrons in the active layer. We demonstrate this effect\nin the devices composed of monolayer graphene and LaAlO3/SrTiO3\nheterointerface, an inherently non-uniform superconductor described by\nJosephson junction arrays. Remarkable drag signal is observed in the\nsuperconducting transition regime of the LaAlO3/SrTiO3 interface, with its sign\nindependent of the carrier type in the graphene layer. The estimated\npassive-to-active ratio can reach about 0.3 at the optimal gate voltage and the\ntemperature dependence follows that of the typical Josephson energy between\nsuperconducting puddles. Strikingly, the ratio ought to be as large as 10^5 at\nzero temperature by theoretical extrapolation. From engineering perspective,\nour device may work as current or voltage transformers, and the drag mechanism\nlays the foundation for synchronizing Josephson-junction-array-based terahertz\nradiators.",
        "positive": "Signatures of a non-thermal metastable state in copropagating quantum\n  Hall edge channels: A Tomonaga-Luttinger (TL) liquid is known as an integrable system, in which a\nnon-equilibrium many-body state survives without relaxing to a thermalized\nstate. This intriguing characteristic is tested experimentally in copropagating\nquantum Hall edge channels at bulk filling factor nu = 2. The unidirectional\ntransport allows us to investigate the time evolution by measuring the spatial\nevolution of the electronic states. The initial state is prepared with a biased\nquantum point contact, and its spatial evolution is measured with a quantum-dot\nenergy spectrometer. We find strong evidences for a non-thermal metastable\nstate in agreement with the TL theory before the system relaxes to thermal\nequilibrium with coupling to the environment."
    },
    {
        "anchor": "Ensemble Monte Carlo for III-V and Si n-channel FinFETs considering\n  non-equilibrium degenerate statistics and quantum-confined scattering: Particle-based ensemble semi-classical Monte Carlo (MC) methods employ\nquantum corrections (QCs) to address quantum confinement and degenerate carrier\npopulations to model tomorrow's ultra-scaled MOSFETs. Here we present new\napproaches to quantum confinement and carrier degeneracy effects in a\nthree-dimensional (3D) MC device simulator, and illustrate their significance\nthrough simulation of n-channel Si and III-V FinFETs. Original contributions\ninclude our treatment of far-from-equilibrium degenerate statistics and\nQC-based modeling of surface-roughness scattering, as well as considering\nquantum-confined phonon and impurity scattering in 3D. Typical MC simulations\napproximate degenerate carrier populations as Fermi distributions to model the\nPauli-blocking (PB) of scattering to occupied final states. To allow for\nincreasingly far-from-equilibrium non-Fermi carrier distributions in\nultra-scaled devices, we instead generate the final-state occupation\nprobabilities used for PB by sampling the local carrier populations as a\nfunction of energy and energy valley. This process is aided by the use of\nfractional carriers or sub-carriers, which minimizes classical carrier-carrier\nscattering. Quantum confinement effects are addressed through\nquantum-correction potentials (QCPs) generated from Schr\\\"{o}dinger-Poisson\nsolvers, as commonly done. However, we use our valley- and\norientation-dependent QCPs not just to redistribute carriers in real space, or\neven among energy valleys, but also to calculate confinement-dependent phonon,\nimpurity, and surface-roughness scattering rates. FinFET simulations are used\nto illustrate how, collectively, these quantum effects can substantially reduce\nand even eliminate otherwise expected benefits of\nIn$_{\\text{0.53}}$Ga$_{\\text{0.47}}$As FinFETs over otherwise identical Si\nFinFETs, despite higher thermal velocities in\nIn$_{\\text{0.53}}$Ga$_{\\text{0.47}}$As.",
        "positive": "Dielectric nano-antennas for strain engineering in atomically thin\n  two-dimensional semiconductors: Atomically thin two-dimensional semiconducting transition metal\ndichalcogenides (TMDs) can withstand large levels of strain before their\nirreversible damage occurs. This unique property offers a promising route for\ncontrol of the optical and electronic properties of TMDs, for instance by\ndepositing them on nano-structured surfaces, where position-dependent strain\ncan be produced on the nano-scale. Here, we demonstrate strain-induced\nmodifications of the optical properties of mono- and bilayer TMD WSe$_2 $\nplaced on photonic nano-antennas made from gallium phosphide (GaP).\nPhotoluminescence (PL) from the strained areas of the TMD layer is enhanced\nowing to the efficient coupling with the confined optical mode of the\nnano-antenna. Thus, by following the shift of the PL peak, we deduce the\nchanges in the strain in WSe$_2$ deposited on the nano-antennas of different\nradii. In agreement with the presented theory, strain up to $\\approx 1.4 \\%$ is\nobserved for WSe$_2$ monolayers. We also estimate that $>3\\%$ strain is\nachieved in bilayers, accompanied with the emergence of a direct bandgap in\nthis normally indirect-bandgap semiconductor. At cryogenic temperatures, we\nfind evidence of the exciton confinement in the most strained nano-scale parts\nof the WSe$_2$ layers, as also predicted by our theoretical model. Our results,\nof direct relevance for both dielectric and plasmonic nano-antennas, show that\nstrain in atomically thin semiconductors can be used as an additional parameter\nfor engineering light-matter interaction in nano-photonic devices."
    },
    {
        "anchor": "Strain determination in the Si channel above a single SiGe island inside\n  a field effect transistor using nanobeam x-ray diffraction: SiGe islands are used to induce tensile strain in the Si channel of Field\nEffect Transistors to achieve larger transconductance and higher current\ndriveabilities. We report on x-ray diffraction experiments on a single\nfully-processed and functional device with a TiN+Al gate stack and source,\ngate, and drain contacts in place. The strain fields in the Si channel were\nexplored using an x-ray beam focused to 400 nm diameter combined with finite\nelement simulations. A maximum in-plane tensile strain of about 1% in the Si\nchannel was found, which is by a factor of three to four higher than achievable\nfor dislocation-free tensile strained Si in state-of-the-art devices.",
        "positive": "Emission of plasmons by drifting Dirac electrons: where hydrodynamics\n  matters: Direct current in clean semiconductors and metals was recently shown to obey\nthe laws of hydrodynamics in a broad range of temperatures and sample\ndimensions. However, the determination of frequency window for hydrodynamic\nphenomena remains challenging. Here, we reveal a phenomenon being a hallmark of\nhigh-frequency hydrodynamic transport, the Cerenkov emission of plasmons by\ndrifting Dirac electrons. The effect appears in hydrodynamic regime only due to\nreduction of plasmon velocity by electron-electron collisions below the\nvelocity of carrier drift. To characterize the Cerenkov effect quantitatively,\nwe analytically find the high-frequency non-local conductivity of drifting\nDirac electrons across the hydrodynamic-to-ballistic crossover. We find the\ngrowth rates of hydrodynamic plasmon instabilities in two experimentally\nrelevant setups: parallel graphene layers and graphene covered by subwavelength\ngrating, further showing their absence in ballistic regime. We argue that the\npossibility of Cerenkov emission is linked to singular structure of non-local\nconductivity of Dirac materials and is independent on specific dielectric\nenvironment."
    },
    {
        "anchor": "Direct observation of the thickness distribution of ultra thin AlOx\n  barrier in Al/AlOx/Al Josephson junctions: We show that less than 10% of the barrier area dominates the electron\ntunneling in state-of-art Al/AlOx/Al Josephson junctions. They have been\nstudied by transmission electron microscopy, specifically using atomic\nresolution annular dark field (ADF) scanning transmission electron microscopy\n(STEM) imaging. The direct observation of the local barrier thickness shows a\nGaussian distribution of the barrier thickness variation along the junction,\nfrom ~1 nm to ~2 nm in the three junctions we studied. We have investigated how\nthe thickness distribution varies with oxygen pressure (po) and oxidation time\n(to) and we find, in agreement with resistance measurements on similar\njunctions, that an increased to gives a thicker barrier than an increased po.",
        "positive": "Electrically controlled crossing of energy levels in quantum dots in\n  two-dimensional topological insulators: We study the energy spectra of bound states in quantum dots (QDs) formed by\nan electrostatic potential in two-dimensional topological insulator (TI) and\ntheir transformation with changes in QD depth and radius. It is found that,\nunlike a trivial insulator, the energy difference between the levels of the\nground state and first excited state can decrease with decreasing the radius\nand increasing the depth of the QD so that these levels intersect under some\ncritical conditions. The crossing of the levels results in unusual features of\noptical properties caused by intracenter electron transitions. In particular,\nit leads to significant changes of light absorption due to electron transitions\nbetween such levels and to the transient electroluminescence induced by\nelectrical tuning of QD and TI parameters. In the case of magnetic TIs, the\npolarization direction of the absorbed or emitted circularly polarized light is\nchanged due to the level crossing."
    },
    {
        "anchor": "Multiphoton absorption and Rabi oscillations in armchair graphene\n  nanoribbons: We present an analytical approach to the problem of the multiphoton\nabsorption and Rabi oscillations in an armchair graphene nanoribbon (AGNR) in\nthe presence of a time-oscillating strong electric field induced by a light\nwave directed parallel to the ribbon axis. The two-dimensional Dirac equation\nfor the massless electron subject to the ribbon confinement is employed. In the\nresonant approximation the electron-hole pair production rate, associated with\nthe electron transitions between the valence and conduction size-quantized\nsubbands, the corresponding multiphoton absorption coefficient and the\nfrequency of the Rabi oscillations are obtained in an explicit form. We trace\nthe dependencies of the above quantities on the ribbon width and electric field\nstrength for both the multiphoton assisted and tunneling regimes relevant to\nthe time-oscillating and practically constant electric field, respectively. A\nsignificant enhancement effect of the oscillating character of the electric\nfield on the intersubband transitions is encountered. Our analytical results\nare in qualitative agreement with those obtained for the graphene layer by\nnumerical methods. Estimates of the expected experimental values for the\ntypically employed AGNR and laser parameters show that both the Rabi\noscillations and multiphoton absorption are accessible in the laboratory. The\ndata relevant to the intersubband tunneling makes the AGNR a 1D condensed\nmatter analog in which the quantum electrodynamic vacuum decay can be detected\nby applying an external laboratory electric field.",
        "positive": "Evidence of Spin-Filtering in Quantum Constrictions with Spin-Orbit\n  Interaction: A new type of blockade effect - spin-orbit blockade (SOB) - is found in the\nconduction of a quantum dot (QD) made of a material with spin-orbit\ninteraction. The blockade arises from spin-filtering effect in a quantum point\ncontact (QPC), which is a component of the QD. Hence the appearance of the\nblockade itself evidences the spin-filtering effect in the QPC. The lower bound\nof filtering efficiency is estimated to be above 80%."
    },
    {
        "anchor": "Spin Transfer Torques induced by Spin Hall Effect: Spin accumulation and spin transfer torques induced by Spin Hall Effect in\nbi-layer structures comprising ferromagnetic and paramagnetic materials are\ntheoretically investigated. The charge and spin diffusion equations taking into\naccount spin-flip and spin Hall effect are formulated and solved analytically\nand numerically for in structures with simplified and complex geometry,\nrespectively. It is demonstrated that spin torques could be efficiently\nproduced by means of Spin Hall effect which may be further enhanced by\nmodifying structure geometry.",
        "positive": "Physics-Based Compact Modeling of Double-Gate Graphene Field-Effect\n  Transistor Operation Including Description of Two Saturation Modes: Based on diffusion-drift approximation a version of analytic compact model\nfor large-area double-gate graphene field-effect transistor is presented. As\nparts of the model, the electrostatics of double-gate structure is described\nand a unified phenomenological approach for modeling of the two drain current\nsaturation modes is proposed."
    },
    {
        "anchor": "Quantum Dynamics of Magnetic Skyrmions: Consistent Path Integral\n  Formulation: We present a path integral formalism for the intrinsic quantum dynamics of\nmagnetic skyrmions coupled to a thermal background of magnetic fluctuations.\nUpon promoting the skyrmion's collective coordinate $\\boldsymbol{R}$ to a\ndynamic variable and integrating out the magnonic heat bath, we derive the\ngeneralized equation of motion for $\\boldsymbol{R}$ with a non-local damping\nterm that describes a steady-state skyrmion dynamics at finite temperatures.\nBeing essentially temperature dependent, the intrinsic damping is shown to\noriginate from the coupling of thermally activated magnon modes to the\nadiabatic potential driven by a rigid skyrmion motion, which can be regarded as\nanother manifestation of emergent electrodynamics inherent to topological\nmagnetic textures. We further argue that the diagonal components of the damping\nterm act as the source of dissipation and inertia, while its off-diagonal\ncomponents modify the gyrotropic motion of a magnetic skyrmion. By means of\nnumerical calculations for the lattice spin model of chiral ferromagnets, we\nstudy the temperature behavior of the intrinsic damping as a function of\nmagnetic field in periodic and confined geometries. The intrinsic damping is\ndemonstrated to be highly non-local, revealing its quantum-mechanical nature,\nthat becomes more pronounced with increasing temperature. At high temperatures\nwhen the magnon occupation factors are large, the intrinsic damping is shown to\nyield a modified Thiele's equation with the additional non-local dissipative\nand mass terms that exhibit an almost linear temperature behavior. Our results\nprovide a microscopic background for semiclassical magnetization dynamics and\nestablish a framework for understanding spin caloritronics effects in\ntopological magnetic textures.",
        "positive": "Exponentially growing bulk Green functions as signature of nontrivial\n  non-Hermitian winding number in one dimension: A nonzero non-Hermitian winding number indicates that a gapped system is in a\nnontrivial topological class due to the non-Hermiticity of its Hamiltonian.\nWhile for Hermitian systems nontrivial topological quantum numbers are\nreflected by the existence of edge states, a nonzero non-Hermitian winding\nnumber impacts a system's bulk response. To establish this relation, we\nintroduce the bulk Green function, which describes the response of a gapped\nsystem to an external perturbation on timescales where the induced excitations\nhave not propagated to the boundary yet, and show that it will grow in space if\nthe non-Hermitian winding number is nonzero. Such spatial growth explains why\nthe response of non-Hermitian systems on longer timescales, where excitations\nhave been reflected at the boundary repeatedly, may be highly sensitive to\nboundary conditions. This exponential sensitivity to boundary conditions\nexplains the breakdown of the bulk-boundary correspondence in non-Hermitian\nsystems: topological invariants computed for periodic boundary conditions no\nlonger predict the presence or absence of boundary states for open boundary\nconditions."
    },
    {
        "anchor": "Charge-carrier-induced frequency renormalization, damping and heating of\n  vibrational modes in nanoscale junctions: In nanoscale junctions the interaction between charge carriers and the local\nvibrations results in renormalization, damping and heating of the vibrational\nmodes. We here formulate a nonequilibrium Green's functions based theory to\ndescribe such effects. Studying a generic junction model with an off-resonant\nelectronic level, we find a strong bias dependence of the frequency\nrenormalization and vibrational damping accompanied by pronounced nonlinear\nvibrational heating in junctions with intermediate values of the coupling to\nthe leads. Combining our theory with ab-initio calculations we furthermore show\nthat the bias dependence of the Raman shifts and linewidths observed\nexperimentally in an OPV3 junction [D. Ward et al., Nature Nano. 6, 33 (2011)]\nmay be explained by a combination of dynamic carrier screening and molecular\ncharging.",
        "positive": "Modulated Interlayer Exciton Properties in a Two-Dimensional Moire\n  Crystal: Twisted van der Waals heterostructures and the corresponding superlattices,\nmoire superlattices, are remarkable new material platforms, in which electron\ninteractions and excited-state properties can be engineered. Particularly, the\nband offsets between adjacent layers can separate excited electrons and holes,\nforming interlayer excitons that exhibit unique optical properties. In this\nwork, we employ the first-principles GW-Bethe-Salpeter Equation (BSE) method to\ncalculate quasiparticle band gaps, interlayer excitons, and their modulated\nexcited-state properties in twisted MoSe2/WSe2 bilayers that are of broad\ninterest currently. In addition to achieving good agreements with the measured\ninterlayer exciton energies, we predict a more than 100-meV lateral quantum\nconfinement on quasiparticle energies and interlayer exciton energies, guiding\nthe effort on searching for localized quantum emitters and simulating the\nHubbard model in two-dimensional twisted structures. Moreover, we find that the\noptical dipole oscillator strength and radiative lifetime of interlayer\nexcitons are modulated by a few orders of magnitude across moire supercells,\nhighlighting the potential of using moire crystals to engineer exciton\nproperties for optoelectronic applications."
    },
    {
        "anchor": "Friedel phase discontinuity and bound states in the continuum in quantum\n  dot systems: n this article we study the Friedel phase of the electron transport in two\ndifferent systems of quantum dots which exhibit bound states in the continuum\n(BIC). The Friedel phase jumps abruptly in the energies of the BICs, which is\nassociated to the vanishing width of these states, as shown by Friedrich and\nWintgen in Phys. Rev. A \\textbf{31}, 3964 (1985). This odd behavior of the\nFriedel phase has consequences in the charge through the Friedel sum rule.\nNamely, if the energy of the BIC drops under the Fermi energy the charge\nchanges abruptly in a unity. We show that this behavior closely relates with\ndiscontinuities in the conductance predicted for interacting quantum dot\nsystems.",
        "positive": "Entanglement subspaces, trial wavefunctions, and special Hamiltonians in\n  the fractional quantum Hall effect: We consider spaces of trial wavefunctions for ground states and edge\nexcitations in the fractional quantum Hall effect that can be obtained in\nvarious ways. In one way, functions are obtained by analyzing the entanglement\nof the ground state wavefunction, partitioned into two parts. In another,\nfunctions are defined by the way in which they vanish as several coordinates\napproach the same value, or by a projection-operator Hamiltonian that enforces\nthose conditions. In a third way, functions are given by conformal blocks from\na conformal field theory (CFT). These different spaces of functions are closely\nrelated. The use of CFT methods permits an algebraic formulation to be given\nfor all of them. In some cases, we can prove that there is a ground state, a\nHamiltonian, and a CFT such that, for any number of particles, all of these\nspaces are the same. For such cases, this resolves several questions and\nconjectures: it gives a finite-size bulk-edge correspondence, and we can use\nthe analysis of functions to construct a projection-operator Hamiltonian that\nproduces those functions as zero-energy states. For a model related to the N=1\nsuperconformal algebra, the corresponding Hamiltonian imposes vanishing\nproperties involving only three particles; for this we determine all the\nwavefunctions explicitly. We do the same for a sequence of models involving the\nM(3,p) Virasoro minimal models that has been considered previously, using\nresults from the literature. We exhibit the Hamiltonians for the first few\ncases of these. The techniques we introduce can be applied in numerous examples\nother than those considered here."
    },
    {
        "anchor": "Topological Insulator-Based van der Waals Heterostructures for Effective\n  Control of Massless and Massive Dirac Fermions: Three dimensional (3D) topological insulators (TIs) are an important class of\nmaterials with applications in electronics, spintronics and quantum computing.\nWith the recent development of truly bulk insulating 3D TIs, it has become\npossible to realize surface dominated phenomena in electrical transport\nmeasurements e.g. the quantum Hall (QH) effect of massless Dirac fermions in\ntopological surface states (TSS). However, to realize more advanced devices and\nphenomena, there is a need for a platform to tune the TSS or modify them e.g.\ngap them by proximity with magnetic insulators, in a clean manner. Here we\nintroduce van der Waals (vdW) heterostructures in the form of topological\ninsulator/insulator/graphite to effectively control chemical potential of the\nTSS. Two types of gate dielectrics, normal insulator hexagonal boron nitride\n(hBN) and ferromagnetic insulator Cr2Ge2Te6 (CGT) are utilized to tune charge\ndensity of TSS in the quaternary TI BiSbTeSe2. hBN/graphite gating in the QH\nregime shows improved quantization of TSS by suppression of magnetoconductivity\nof massless Dirac fermions. CGT/graphite gating of massive Dirac fermions in\nthe QH regime yields half-quantized Hall conductance steps and a measure of the\nDirac gap. Our work shows the promise of the vdW platform in creating advanced\nhigh-quality TI-based devices.",
        "positive": "Exact approaches to charged particle motion in a time-dependent\n  flux-driven ring: We consider a charged particle which is driven by a time-dependent flux\nthreading a circular ring system. Various approaches including classical\ntreatment, Fourier expansion method, time-evolution method, and\nLewis-Riesenfeld method are used and compared to solve the time-dependent\nproblem. By properly managing the boundary condition of the system, a\ntime-dependent wave function of the charged particle can be obtained by using a\nnon-Hermitian time-dependent invariant, which is a specific linear combination\nof initial angular-momentum and azimuthal-angle operators. The eigenfunction of\nthe linear invariant can be realized as a Gaussian-type wave packet with a peak\nmoving along the classical angular trajectory, while the distribution of the\nwave packet is determined by the ratio of the coefficient of the initial angle\nto that of the initial canonical angular momentum. In this topologically\nnontrivial system, we find that although the classical trajectory and angular\nmomentum can determine the motion of the wave packet; however, the peak\nposition is no longer an expectation value of the angle operator. Therefore, in\nsuch a system, the Ehrenfest theorem is not directly applicable."
    },
    {
        "anchor": "Localisation, delocalisation, and topological transitions in disordered\n  2D quantum walks: We investigate time-independent disorder on several two-dimensional\ndiscrete-time quantum walks. We find numerically that, contrary to claims in\nthe literature, random onsite phase disorder, spin-dependent or otherwise,\ncannot localise the Hadamard quantum walk; rather, it induces diffusive\nspreading of the walker. In contrast, split-step quantum walks are generically\nlocalised by phase disorder. We explain this difference by showing that the\nHadamard walk is a special case of the split-step quantum walk, with parameters\ntuned to a critical point at a topological phase transition. We show that the\ntopological phase transition can also be reached by introducing strong disorder\nin the rotation angles. We determine the critical exponent for the divergence\nof the localisation length at the topological phase transition, and find\n$\\nu=2.6$, in both cases. This places the two-dimensional split-step quantum\nwalk in the universality class of the quantum Hall effect.",
        "positive": "Kinetics of intermediate-mediated self-assembly in nano-sized materials:\n  a generic model: We propose in this paper a generic model of a non-standard aggregation\nmechanism for self-assembly processes of a class of materials involving the\nmediation of intermediates consisting of a polydisperse population of\nnano-sized particles. The model accounts for a long induction period in the\nprocess. The proposed mechanism also gives insight on future experiments aiming\nat a more comprehensive picture of the role of self-organization in\nself-assembly processes."
    },
    {
        "anchor": "Generalization of Phonon Confinement Model for Interpretation of Raman\n  Line-Shape from Nano-Silicon: A comparative analysis of two Raman line-shape functions has been carried out\nto validate the true representation of experimentally observed Raman scattering\ndata for semiconducting nanomaterials. A modified form of already existing\nphonon confinement model incorporates two basic considerations, phonon momentum\nconservation and shift in zone centre phonon frequency. After incorporation of\nthe above mentioned two factors, a rather symmetric Raman line-shape is\ngenerated which is in contrary to the usual asymmetric Raman line-shapes\nobtained from nanostructured semiconductor. By fitting an experimentally\nobserved Raman scattering data from silicon nanostructures, prepared by metal\ninduced etching, it can be established that the Raman line-shape obtained\nwithin the framework of phonon confinement model is a true representative Raman\nline-shape of sufficiently low dimensions semiconductors.",
        "positive": "Spin-dependent electron transport in waveguide with continuous shape: We study effects of the shape of a two-dimensional waveguide on the\nspin-dependent electron transport in the presence of spin-orbit coupling. The\ntransition from classical motion to the tunneling regime can be controlled\nthere by modulating the strength of spin-orbit coupling if the waveguide has a\nconstriction. The spin precession strongly depends on the shape of the\nwaveguide."
    },
    {
        "anchor": "Quantum interference of pseudospin-1 fermions: Quantum interference is studied in a three-band model of pseudospin-one\nfermions in the $\\alpha-\\mathcal{T}_3$ lattice. We derive a general formula for\nmagnetoconductivity that predicts a rich crossover between weak localization\n(WL) and weak antilocalization (WAL) in various scenarios. Recovering the known\nresults for graphene ($\\alpha=0$), we remarkably discover that WAL is notably\nenhanced when one deviates slightly from the graphene lattice, i.e. when\n$\\alpha>0$, even though Berry's phase is no longer $\\pi$. This is attributed to\nthe presence of multiple Cooperon channels. Upon further increasing $\\alpha$, a\ncrossover to WL occurs that is maximal for the case of the Dice lattice\n($\\alpha=1$). Our work distinctly underscores the role of non-trivial band\ntopology in the localization properties of electrons confined to the\ntwo-dimensional $\\alpha-\\mathcal{T}_3$ lattice.",
        "positive": "Electrical detection of spin-polarized current in topological insulator\n  Bi1.5Sb0.5Te1.7Se1.3: Spin-momentum locked (SML) topological surface state (TSS) provides exotic\nproperties for spintronics applications. The spin-polarized current, which\nemerges owing to the SML, can be directly detected by performing spin\npotentiometric measurement. We observed spin-polarized current using a bulk\ninsulating topological insulator (TI), Bi1.5Sb0.5Te1.7Se1.3, and Co as the\nferromagnetic spin probe. The spin voltage was probed with varying the bias\ncurrent, temperature, and gate voltage. Moreover, we observed non-local\nspin-polarized current, which is regarded as a distinguishing property of TIs.\nThe spin-polarization ratio of the non-local current was larger than that of\nthe local current. These findings could reveal a more accurate approach to\ndetermine spin-polarization ratio at the TSS."
    },
    {
        "anchor": "Analogy and dissimilarity of excitons in monolayer and bilayer of\n  MoSe$_2$: Excitons in thin layers of semiconducting transition metal dichalcogenides\nare highly subject to the strongly modified Coulomb electron-hole interaction\nin these materials. Therefore, they do not follow the model system of a\ntwo-dimensional hydrogen atom. We investigate experimentally and theoretically\nexcitonic properties in both the monolayer (ML) and the bilayer (BL) of\nMoSe$_2$ encapsulated in hexagonal BN. The measured magnetic field evolutions\nof the reflectance contrast spectra of the MoSe$_2$ ML and BL allow us to\ndetermine $g$-factors of intralayer A and B excitons, as well as the $g$-factor\nof the interlayer exciton. We explain the dependence of $g$-factors on the\nnumber of layers and excitation state using first principles calculations.\nFurthermore, we demonstrate that the experimentally measured ladder of\nexcitonic $s$ states in the ML can be reproduced using the $\\mathbf{k\\cdot p}$\napproach with the Rytova-Keldysh potential that describes the electron-hole\ninteraction. In contrast, the analogous calculation for the BL case requires\ntaking into account the out-of-plane dielectric response of the MoSe$_2$ BL.",
        "positive": "Magnetoconductivity in Weyl semimetals: Effect of chemical potential and\n  temperature: We present the detailed analyses of magneto-conductivities in a Weyl\nsemimetal within Born and self-consistent Born approximations. In the presence\nof the charged impurities, the linear magnetoresistance can happen when the\ncharge carriers are mainly from the zeroth (n=0) Landau level. Interestingly,\nthe linear magnetoresistance is very robust against the change of temperature,\nas long as the charge carriers mainly come from the zeroth Landau level. We\ndenote this parameter regime as the high-field regime. On the other hand, the\nlinear magnetoresistance disappears once the charge carriers from the higher\nLandau levels can provide notable contributions. Our analysis indicates that\nthe deviation from the linear magnetoresistance is mainly due to the deviation\nof the longitudinal conductivity from the $1/B$ behavior. We found two\nimportant features of the self-energy approximation: 1. a dramatic jump of\n$\\sigma_{xx}$, when the $n=1$ Landau level begins to contribute charge\ncarriers, which is the beginning point of the middle-field regime, when\ndecreasing the external magnetic field from high field; 2. In the low-field\nregime $\\sigma_{xx}$ shows a $B^{-5/3}$ behavior and results the\nmagnetoresistance $\\rho_{xx}$ to show a $B^{1/3}$ behavior. The detailed and\ncareful numerical calculation indicates that the self-energy approximation\n(including both the Born and the self-consistent Born approximations) does not\nexplain the recent experimental observation of linear magnetoresistance in Weyl\nsemimetals."
    },
    {
        "anchor": "Single-Dirac-Cone topological surface states on\n  pseudo-IV-VI-semimetal/semiconductors: Thallium-based III-V-VI2 Ternary\n  Chalcogenides: We have investigated several classes of strong spin-orbit chalcogenides\nrelated to the (Pb,Sn)Te series studied in connection with the Dirac fermion\nphysics in the 1980s. Our first-principle theoretical calculations suggest that\nternary chalcogenides TlBiX$_2$ and TlSbX$_2$ (X=Te, Se, S) series harbor small\nbandgap topological insulators with single Dirac cone on some selective\nsurfaces whereas the isostructural and isoelectronic silver-based AgBiX$_2$ and\nAgSbX$_2$ (X=Te, Se, S) series do not. We find that several Tl-compounds are in\nthe vicinity of a topological critical point. We identify the precise surface\ntermination that realizes the single Dirac cone. The single-Dirac-cone surface\nis shown to be correlated with a termination that minimizes dangling bonding\neffects favorable for ARPES experiments. Our results further suggest that this\nclass of topological semi-metals may harbor odd-parity topological\nsuperconductors similar to the possibility proposed for CuxBi2Se3 (T_c ~ 4K).",
        "positive": "Wiedemann-Franz law for massless Dirac fermions with implications for\n  graphene: In the 2016 experiment by Crossno et al. [Science 351, 1058 (2016)],\nelectronic contribution to the thermal conductivity of graphene was found to\nviolate the well-known Wiedemann-Franz (WF) law for metals. At liquid nitrogen\ntemperatures, the thermal to electrical conductivity ratio of charge-neutral\nsamples was more than 10 times higher than predicted by the WF law, what was\nattributed to interactions between particles leading to collective behavior\ndescribed by hydrodynamics. Here we show, by adapting the handbook derivation\nof the WF law to the case of massless Dirac fermions, that significantly\nenhanced thermal conductivity should appear also in few- or even sub-kelvin\ntemperatures, where the role of interactions can be neglected. The comparison\nwith numerical results obtained within the Landauer-B\\\"uttiker formalism for\nrectangular and disk-shaped (Corbino) devices in ballistic graphene is also\nprovided."
    },
    {
        "anchor": "Anisotropic Particle-Hole Excitations in Black Phosphorus: We report about the energy and momentum resolved optical response of black\nphosphorus (BP) in its bulk form. Along the armchair direction of the puckered\nlayers we find a highly dispersive mode that is trongly suppressed in the\nperpendicular (zig-zag) direction. This mode emerges out of the single-particle\ncontinuum for finite values of momentum and is therefore interpreted as an\nexciton. We argue that this exciton, which has already been predicted\ntheoretically for phosphorene -- the monolayer form of BP -- can be detected by\nconventional optical spectroscopy in the two-dimensional case and might pave\nthe way for optoelectronic applications of this emerging material.",
        "positive": "Knots and Non-Hermitian Bloch Bands: Knots have a twisted history in quantum physics. They were abandoned as\nfailed models of atoms. Only much later was the connection between knot\ninvariants and Wilson loops in topological quantum field theory discovered.\nHere we show that knots tied by the eigenenergy strings provide a complete\ntopological classification of one-dimensional non-Hermitian (NH) Hamiltonians\nwith separable bands. A $\\mathbb{Z}_2$ knot invariant, the global biorthogonal\nBerry phase $Q$ as the sum of the Wilson loop eigenphases, is proved to be\nequal to the permutation parity of the NH bands. We show the transition between\ntwo phases characterized by distinct knots occur through exceptional points and\ncome in two types. We further develop an algorithm to construct the\ncorresponding tight-binding NH Hamiltonian for any desired knot, and propose a\nscheme to probe the knot structure via quantum quench. The theory and algorithm\nare demonstrated by model Hamiltonians that feature for example the Hopf link,\nthe trefoil knot, the figure-8 knot and the Whitehead link."
    },
    {
        "anchor": "Influence of O2 and N2 on the conductivity of carbon nanotube networks: We have performed experiments on single-wall carbon nanotube (SWNT) networks\nand compared with density-functional theory (DFT) calculations to identify the\nmicroscopic origin of the observed sensitivity of the network conductivity to\nphysisorbed O2 and N2. Previous DFT calculations of the transmission function\nfor isolated pristine SWNTs have found physisorbed molecules have little\ninfluence on their conductivity. However, by calculating the four-terminal\ntransmission function of crossed SWNT junctions, we show that physisorbed O2\nand N2 do affect the junction's conductance. This may be understood as an\nincrease in tunneling probability due to hopping via molecular orbitals. We\nfind the effect is substantially larger for O2 than for N2, and for\nsemiconducting rather than metallic SWNTs junctions, in agreement with\nexperiment.",
        "positive": "Entanglement of spin chains with general boundaries and of dissipative\n  systems: We analyze the entanglement properties of spins (qubits) close to the\nboundary of spin chains in the vicinity of a quantum critical point and show\nthat the concurrence at the boundary is significantly different from the one of\nbulk spins. We also discuss the von Neumann entropy of dissipative environments\nin the vicinity of a (boundary) critical point, such as two Ising-coupled\nKondo-impurities or the dissipative two-level system. Our results indicate that\nthe entanglement (concurrence and/or von Neumann entropy) changes abruptly at\nthe point where coherent quantum oscillations cease to exist. The phase\ntransition modifies significantly less the entanglement if no symmetry breaking\nfield is applied and we argue that this might be a general property of the\nentanglement of dissipative systems. We finally analyze the entanglement of an\nharmonic chain between the two ends as function of the system size."
    },
    {
        "anchor": "Dynamical response of dissipative helical edge states: Quantum spin Hall insulators are characterized by topologically protected\ncounterpropagating edge states. Here we study the dynamical response of these\nhelical edge states under a time-dependent flux biasing, in the presence of a\nheat bath. It is shown that the relaxation time of the edge carriers can be\ndetermined from a measurement of the dissipative response of topological\ninsulator disks. The effects of various perturbations, including Zeeman\ncoupling and disorder, are also discussed.",
        "positive": "Scattering matrix approach to the description of quantum electron\n  transport: We consider the scattering matrix approach to quantum electron transport in\nmeso- and nano-conductors. This approach is an alternative to the more\nconventional kinetic equation and Green's function approaches, and often is\nmore efficient for coherent conductors (especially for proving general\nrelations) and typically more transparent. We provide a description of both\ntime-averaged quantities (for example, current-voltage characteristics) and\ncurrent fluctuations in time -- noise, as well as full counting statistics of\ncharge transport in a finite time. In addition to normal conductors, we\nconsider contacts with superconductors and Josephson junctions."
    },
    {
        "anchor": "\"Reservoir model\" for shallow modulation-doped digital magnetic quantum\n  wells: Digital Magnetic Heterostructures (DMH) are semiconductor structures with\nmagnetic monolayers. Here we study electronic and magneto-transport properties\nof shallow modulation-doped (ZnSe/ZnCdSe) DMHs with spin-5/2 Mn impurities. We\ncompare the \"reservoir\" model, possibly relevant to shallow geometries, to the\nusual \"constant-density\" model. Our results are obtained by solving the\nKohn-Sham equations within the Local Spin Density Approximation (LSDA). In the\npresence of a magnetic field, we show that both models exhibit characteristic\nbehaviors for the electronic structure, two-dimensional carrier density, Fermi\nlevel and transport properties. Our results illustrate the relevance of\nexchange and correlation effects in the study shallow heterostructures of the\ngroup II-VI.",
        "positive": "Edge states of hydrogen terminated monolayer materials: silicene,\n  germanene and stanene ribbons: We investigate the energy dispersion of the edge states in zigzag silicene,\ngermanene and stanene nanoribbons with and without hydrogen termination based\non a multi-orbital tight-binding model. Since the low buckled structures are\ncrucial for these materials, both the $\\pi$ and $\\sigma$ orbitals have a strong\ninfluence on the edge states, different from the case for graphene nanoribbons.\nThe obtained dispersion of helical edge states is nonlinear, similar to that\nobtained by first-principles calculations. On the other hand, the dispersion\nderived from the single-orbital tight-binding model is always linear.\nTherefore, we find that the non-linearity comes from the multi-orbital effects,\nand accurate results cannot be obtained by the single-orbital model but can be\nobtained by the multi-orbital tight-binding model. We show that the\nmulti-orbital model is essential for correctly understanding the dispersion of\nthe edge states in tetragen nanoribbons with a low buckled geometry."
    },
    {
        "anchor": "Parity symmetry as the origin of 'spin' in the quantum spin Hall effect: The quantum spin Hall effect arises due to band inversion in topological\ninsulators, and has the defining characteristic that it hosts helical edge\nchannels at zero magnetic field, leading to a finite spin Hall conductivity.\nThe spin Hall conductivity is understood as the difference of the contributions\nof two spin states. In the effective four-band BHZ model, these two spin states\nappear as two uncoupled blocks in the Hamiltonian matrix. However, this idea\nbreaks down if additional degrees of freedom are considered. The two blocks\ncannot be identified by proper spin $S_z$ or total angular momentum $J_z$, both\nnot conserved quantum numbers. In this work, we discuss a notion of block\nstructure for the more general k.p model, defined by a conserved quantum number\nthat we call isoparity, a combination of parity $z\\to-z$ and spin. Isoparity\nremains a conserved quantity under a wide range of conditions, in particular in\npresence of a perpendicular external magnetic field. From point-group\nconsiderations, isoparity is fundamentally defined as the action of $z\\to-z$ on\nthe spatial and spinorial degrees of freedom. Since time reversal anticommutes\nwith isoparity, the two blocks act as Kramers partners. The combination of\nconductivity and isoparity defines spin conductivity. This generalized notion\nof spin Hall conductivity uncovers the meaning of 'spin': It is not the proper\nspin $S_z$, but a crystal symmetry that is realized by a spinorial\nrepresentation.",
        "positive": "Thermodynamic properties of a quantum Hall anti-dot interferometer: We study quantum Hall interferometers in which the interference loop\nencircles a quantum anti-dot. We base our study on thermodynamic\nconsiderations, which we believe reflect the essential aspects of interference\ntransport phenomena. We find that similar to the more conventional Fabry-Perot\nquantum Hall interferometers, in which the interference loop forms a quantum\ndot, the anti-dot interferometer is affected by the electro-static Coulomb\ninteraction between the edge modes defining the loop. We show that in the\nAharonov-Bohm regime, in which effects of fractional statistics should be\nvisible, is easier to access in interferometers based on anti-dots than in\nthose based on dots. We discuss the relevance of our results to recent\nmeasurements on anti-dots interferometers."
    },
    {
        "anchor": "Acoustic Phonon-Assisted Resonant Tunneling via Single Impurities: We perform the investigations of the resonant tunneling via impurities\nembedded in the AlAs barrier of a single GaAs/AlGaAs heterostructure. In the\n$I(V)$ characteristics measured at 30mK, the contribution of individual donors\nis resolved and the fingerprints of phonon assistance in the tunneling process\nare seen. The latter is confirmed by detailed analysis of the tunneling rates\nand the modeling of the resonant tunneling contribution to the current.\nMoreover, fluctuations of the local structure of the DOS (LDOS) and Fermi edge\nsingularities are observed.",
        "positive": "Regularized framework of a Weyl equation for describing a Weyl\n  semimetal: Application to the case with a screw dislocation: The term Weyl semimetal originates from the fact that its energy dispersion\nobeys a Weyl equation. However, a Weyl equation itself cannot fully describe\nthe electron states in an actual bounded geometry. For example, the appearance\nof chiral surface states, which is a characteristic feature of a Weyl\nsemimetal, cannot be captured with a Weyl equation. This indicates that some\ndegree of freedom is lost when a Weyl equation is derived from a microscopic\nmodel of a Weyl semimetal. To overcome this difficulty, we present a framework\nconsisting of a Weyl equation and a supplementary equation, which can be\nderived from a microscopic model. Applying this framework to a cylindrical\nsystem in the presence of a screw dislocation, we show that it appropriately\ndescribes the chiral surface states and one-dimensional chiral modes along a\ndislocation line. The local charge current induced by these chiral states is\ndetermined in an analytical manner."
    },
    {
        "anchor": "Charge Current Density from the Scattering Matrix: A method to derive the charge current density and its quantum mechanical\ncorrelation from the scattering matrix is discussed for quantum scattering\nsystems described by a time-dependent Hamiltonian operator. The current density\nand charge density are expressed with the help of functional derivatives with\nrespect to the vector potential and the electric potential. A condition imposed\nby the requirement that these local quantities are gauge invariant is\nconsidered. Our formulas lead to a direct relation between the local density of\nstates and the total current density at a given energy. To illustrate the\nresults we consider, as an example, a chiral ladder model.",
        "positive": "Spin-dependent transmission in curved graphene superlattice: We investigate spin-dependent transmission in a curved graphene superlattice\nof $N$ cells where each one is made up of four regions. The first is concave,\nand the third is convex, two arcs of circles separated by a distance $d$ from\nflat graphene sheets. The tunneling analysis allows us to determine all\ntransmission and reflection channels associated with our system. As a result,\nwe show that the number of cells acts by decreasing the transmissions with the\nsame spin. We predict a solid spin-filtering effect when $d$ and $N$ are\nsufficiently large. Finally, it is determined that the degree and duration of\nsuppression of the transmissions with the same spin over a range of energy are\ncontrollable using $d$."
    },
    {
        "anchor": "Proximity Enhanced Quantum Spin Hall State in Graphene: Graphene is the first model system of two-dimensional topological insulator\n(TI), also known as quantum spin Hall (QSH) insulator. The QSH effect in\ngraphene, however, has eluded direct experimental detection because of its\nextremely small energy gap due to the weak spin-orbit coupling. Here we predict\nby ab initio calculations a giant (three orders of magnitude) proximity induced\nenhancement of the TI energy gap in the graphene layer that is sandwiched\nbetween thin slabs of Sb2Te3 (or MoTe2). This gap (1.5 meV) is accessible by\nexisting experimental techniques, and it can be further enhanced by tuning the\ninterlayer distance via compression. We reveal by a tight-binding study that\nthe QSH state in graphene is driven by the Kane-Mele interaction in competition\nwith Kekul\\'e deformation and symmetry breaking. The present work identifies a\nnew family of graphene-based TIs with an observable and controllable bulk\nenergy gap in the graphene layer, thus opening a new avenue for direct\nverification and exploration of the long-sought QSH effect in graphene.",
        "positive": "A solvable quantum model of dynamic nuclear polarization in quantum dots: We present a quantum mechanical theory of optically induced dynamic nuclear\npolarization applicable to quantum dots and other interacting spin systems. The\nexact steady state of the optically driven coupled electron-nuclear system is\ncalculated under the assumption of uniform hyperfine coupling strengths (box\nmodel) for an arbitrary number of nuclear spins. This steady state is given by\na tractable expression that allows for an intuitive interpretation in terms of\nspin-flip rates. Based on this result, we investigate the nuclear spin\nbehaviour for different experimental parameter regimes and find that our model\nreproduces the flat-top and triangular absorption line shapes seen in various\nexperiments (line dragging) under the assumption of fast electron spin\ndephasing due to phonons and co-tunneling. The mechanism responsible for line\ndragging has been a matter of controversy so far; in contrast with previous\nworks, we show that the effect can be explained solely in terms of the contact\nhyperfine interaction, without the need to introduce non-collinear terms or\nother types of electron-nuclear interactions. Furthermore we predict a novel\nnuclear spin polarization effect: under particular, experimentally realistic\nconditions, the nuclear spin system tends to become sharply polarized in such a\nway as to cancel the effect of the external magnetic field. This effect can\ntherefore suppress electron spin dephasing due to inhomogeneous broadening,\nwhich could have important repercussions for quantum technological\napplications."
    },
    {
        "anchor": "A hands-on laboratory and computational experience for nanoscale\n  materials, devices and systems education for electronics, spintronics and\n  optoelectronics: To enhance the undergraduate and graduate engineering education for nanoscale\nmaterials, devices and systems, we report a multi-disciplinary course based on\nthe integration of theory, hands-on laboratory and hands-on computation into a\nsingle curriculum. The hands-on laboratory modules span various\ndimensionalities of nanomaterials as well as applications in logic, memory, and\nenergy harvesting. In the hands-on computational exercises, students simulate\nthe material and the device characteristics, and in some cases, design the\nexperimental process flow to fabricate and characterize the devices and\nsystems. Such a course not only grooms the students for multi-disciplinary\ncollaborative activities in nanoscience and nanoengineering, but also prepares\nthem well for future academic or industrial pursuit in this area.",
        "positive": "Majorana nanowires for topological quantum computation: Majorana bound states are quasiparticle excitations localized at the\nboundaries of a topologically nontrivial superconductor. They are zero-energy,\ncharge-neutral, particle-hole symmetric, and spatially-separated end modes\nwhich are topologically protected by the particle-hole symmetry of the\nsuperconducting state. Due to their topological nature, they are robust against\nlocal perturbations and, in an ideal environment, free from decoherence.\nFurthermore, unlike ordinary fermions and bosons, the adiabatic exchange of\nMajorana modes is noncommutative, i.e., the outcome of exchanging two or more\nMajorana modes depends on the order in which exchanges are performed. These\nproperties make them ideal candidates for the realization of topological\nquantum computers. In this tutorial, I will present a pedagogical review of 1D\ntopological superconductors and Majorana modes in quantum nanowires. I will\ngive an overview of the Kitaev model and the more realistic Oreg-Lutchyn model,\ndiscuss the experimental signatures of Majorana modes, and highlight their\nrelevance in the field of topological quantum computation. This tutorial may\nserve as a pedagogical and relatively self-contained introduction for graduate\nstudents and researchers new to the field, as well as an overview of the\ncurrent state-of-the-art of the field and a reference guide to specialists."
    },
    {
        "anchor": "Towards full counting statistics for the Anderson impurity model: We analyse the full counting statistics (FCS) of the charge transport through\nthe Anderson impurity model (AIM) and similar systems with a single conducting\nchannel. The object of principal interest is the generating function for the\ncumulants of charge current distribution. We derive an exact analytic formula\nrelating the FCS generating function to the self energy of the system in the\npresence of the measuring field. We first check that our approach reproduces\ncorrectly known results in simple limits, like the FCS of the resonant level\nsystem (AIM without Coulomb interaction). We then proceed to study the FCS for\nthe AIM both perturbatively in the Coulomb interaction and in the Kondo regime\nat the Toulouse point (we also study a related model of a spinless single-site\nquantum dot coupled to two half-infinite metallic leads in the Luttinger liquid\nphase at a special interaction strength). At zero temperature the FCS turns out\nto be binomial for small voltages. For the generic case of arbitrary energy\nscales the FCS is shown to be captured very well by generalisations of the\nLevitov-Lesovik type formula. Surprisingly, the FCS for the AIM indicates a\npresence of coherent electron pair tunnelling in addition to conventional\nsingle-particle processes. By means of perturbative expansions around the\nToulouse point we succeeded in showing the universality of the binomial FCS at\nzero temperature in linear response. Based on our general formula for the FCS\nwe then argue for a more general binomial theorem stating that the linear\nresponse zero-temperature FCS for any interacting single-channel set-up is\nalways binomial.",
        "positive": "Dirac Electrons on a Sharply Edged Surface of Topological Insulators: An unpaired gapless Dirac electron emergent at the surface of a strong\ntopological insulator (STI) is protected by the bulk-surface correspondence and\nbelieved to be immune to backward scattering. It is less obvious, however, and\nyet to be verified explicitly whether such a gapless Dirac state is smoothly\nextended over the entire surface when the surface is composed of more than a\nsingle facet with different orientations in contact with one another at sharp\ncorner edges (typically forming a steplike structure). In the realistic\nsituation that we consider, the anisotropy of the sample leads to different\ngroup velocities in each of such facets. Here, we propose that much insight on\nthis issue can be obtained by studying the electronic states on a hyperbolic\nsurface of an STI. By explicitly constructing the surface effective\nHamiltonian, we demonstrate that no backward scattering takes place at a\nconcave $90^\\circ$ step edge. A strong renormalization of the velocity in the\nclose vicinity of the step edge is also suggested."
    },
    {
        "anchor": "Suppressing photochemical reactions with quantized light fields: Photoisomerization, i.e., a change of molecular structure after absorption of\na photon, is one of the most fundamental photochemical processes. It can\nperform desirable functionality, e.g., as the primary photochemical event in\nhuman vision, where it stores electronic energy in the molecular structure, or\nfor possible applications in solar energy storage and as memories, switches,\nand actuators; but it can also have detrimental effects, for example as an\nimportant damage pathway under solar irradiation of DNA, or as a limiting\nfactor for the efficiency of organic solar cells. While photoisomerization can\nbe avoided by shielding the system from light, this is of course not a viable\npathway for approaches that rely on the interaction with external light (such\nas solar cells or solar energy storage). Here, we show that strong coupling of\norganic molecules to a confined light mode can be used to strongly suppress\nphotoisomerization, and thus convert molecules that normally show fast\nphotodegradation into photostable forms.",
        "positive": "High-performance planar nanoscale dielectric capacitors: We propose a model for planar nanoscale dielectric capacitor consisting of a\nsingle layer, insulating hexagonal boron nitride (BN) stripe placed between two\nmetallic graphene stripes, all forming commensurately a single atomic plane.\nFirst-principles density functional calculations on these nanoscale capacitors\nfor different levels of charging and different widths of graphene - BN stripes\nmark high gravimetric capacitance values, which are comparable to those of\nsupercapacitors made from other carbon based materials. Present nanocapacitor\nmodel allows the fabrication of series, parallel and mixed combinations which\noffer potential applications in 2D flexible nanoelectronics, energy storage and\nheat-pressure sensing systems."
    },
    {
        "anchor": "Charge-conserving equilibration of quantum Hall edge states: We address the experimentally relevant situation, where a non-equilibrium\nstate is created at the edge of a quantum Hall system by injecting charge\ncurrent into a chiral edge state with the help of a quantum point contact,\nquantum dots, or mesoscopic Ohmic contact. We show that the commonly accepted\npicture of the full equilibration of a non-equilibrium state at finite\ndistances longer than a characteristic length scale contradicts to the charge\nconservation requirement. We use a phenomenological transmission line model to\naccount for the local equilibration process and the charge and energy\nconserving dynamics of the collective mode. By solving this model in the limit\nof long distances $L$ from the injection point, we demonstrate that the\ncorrection of the electron distribution function to its eventual equilibrium\nform scales down slowly as $1/\\sqrt{L}$.",
        "positive": "Microscopic theory of cavity-enhanced single-photon emission from\n  optical two-photon Raman processes: We consider cavity-enhanced single-photon generation from stimulated\ntwo-photon Raman processes in three-level systems. We compare four fundamental\nsystem configurations, one $\\Lambda$-, one V- and two ladder ($\\Xi$-)\nconfigurations. These can be realized as subsystems of a single quantum dot or\nof quantum-dot molecules. For a new microscopic understanding of the Raman\nprocess, we analyze the Heisenberg equation of motion applying the\ncluster-expansion scheme. Within this formalism an exact and rigorous\ndefinition of a cavity-enhanced Raman photon via its corresponding Raman\ncorrelation is possible. This definition for example enables us to\nsystematically investigate the on-demand potential of Raman-transition-based\nsingle-photon sources. The four system arrangements can be divided into two\nsubclasses, $\\Lambda$-type and V-type, which exhibit strongly different\nRaman-emission characteristics and Raman-emission probabilities. Moreover, our\napproach reveals whether the Raman path generates a single photon or just\ninduces destructive quantum interference with other excitation paths. Based on\nour findings and as a first application, we gain a more detailed understanding\nof experimental data from the literature. Our analysis and results are also\ntransferable to the case of atomic three-level-resonator systems, and can be\nextended to more complicated multi-level schemes."
    },
    {
        "anchor": "Absence of weak antilocalization in ferromagnetic films: We present magnetoresistance measurements performed on ultrathin films of\namorphous Ni and Fe. In these films the Curie temperature drops to zero at\nsmall thickness, making it possible to study the effect of ferromagnetism on\nlocalization. We find that non-ferromagnetic films are characterized by\npositive magnetoresistance. This is interpreted as resulting from weak\nantilocalization due to strong Bychkov-Rashba spin orbit scattering. As the\nfilms become ferromagnetic the magnetoresistance changes sign and becomes\nnegative. We analyze our data to identify the individual contributions of weak\nlocalization, weak antilocalization and anisotropic magnetoresistance and\nconclude that the magnetic order suppresses the influence of spin-orbit effects\non localization phenomena in agreement with theoretical predictions.",
        "positive": "Dynamics of large anisotropic spin in a sub-ohmic dissipative\n  environment close to a quantum-phase transition: We investigate the dynamics of a large anisotropic spin whose easy-axis\ncomponent is coupled to a bosonic bath with a spectral function $J(\\w)\\propto\n\\omega^s$. Such a spin complex might be realized in a single-molecular magnet.\nUsing the non-perturbative renormalization group, we calculate the line of\nquantum-phase transitions in the sub-ohmic regime ($s<1$). These quantum-phase\ntransitions only occur for integer spin $J$. For half-integer $J$, the low\ntemperature fixed-point is identical to the fixed-point of the spin-boson model\nwithout quantum-tunneling between the two levels. Short-time coherent\noscillations in the spin decay prevail even into the localized phase in the\nsub-ohmic regime. The influence of the reorganization energy and the recurrence\ntime on the decoherence in the absence of quantum-tunneling is discussed."
    },
    {
        "anchor": "First-passage time theory of activated rate chemical processes in\n  electronic molecular junctions: Confined nanoscale spaces, electric fields and tunneling currents make the\nmolecular electronic junction an experimental device for the discovery of new,\nout-of-equilibrium chemical reactions. Reaction-rate theory for\ncurrent-activated chemical reactions is developed by combining a Keldysh\nnonequilibrium Green's functions treatment of electrons, Fokker-Planck\ndescription of the reaction coordinate, and Kramers' first-passage time\ncalculations. The NEGF provide an adiabatic potential as well as a diffusion\ncoefficient and temperature with local dependence on the reaction coordinate.\nVan Kampen's Fokker-Planck equation, which describes a Brownian particle moving\nin an external potential in an inhomogeneous medium with a position-dependent\nfriction and diffusion coefficient, is used to obtain an analytic expression\nfor the first-passage time. The theory is applied to several transport\nscenarios: a molecular junction with a single, reaction coordinate dependent\nmolecular orbital, and a model diatomic molecular junction. We demonstrate the\nnatural emergence of Landauer's blowtorch effect as a result of the interplay\nbetween the configuration dependent viscosity and diffusion coefficients. The\nresultant localized heating in conjunction with the bond-deformation due to\ncurrent-induced forces are shown to be the determining factors when considering\nchemical reaction rates; each of which result from highly tunable parameters\nwithin the system.",
        "positive": "Symmetry breaking and spin-orbit coupling for individual vacancy-induced\n  in-gap states in MoS2 monolayers: Spins confined to point defects in atomically-thin semiconductors constitute\nwell-defined atomic-scale quantum systems that are being explored as single\nphoton emitters and spin qubits. Here, we investigate the in-gap electronic\nstructure of individual sulphur vacancies in molybdenum disulphide (MoS2)\nmonolayers using resonant tunneling scanning probe spectroscopy in the Coulomb\nblockade regime. Spectroscopic mapping of defect wavefunctions reveals an\ninterplay of local symmetry breaking by a charge-state dependent Jahn-Teller\nlattice distortion that, when combined with strong (~100 meV) spin-orbit\ncoupling, leads to a locking of an unpaired spin-1/2 magnetic moment to the\nlattice at low temperature, susceptible to lattice strain. Our results provide\nnew insights into spin and electronic structure of vacancy induced in-gap\nstates towards their application as electrically and optically addressable\nquantum systems."
    },
    {
        "anchor": "Negative magnetoresistance and sign change of the planar Hall effect due\n  to the negative off-diagonal effective-mass in Weyl semimetals: We theoretically investigated the magnetoresistance (MR) and planar Hall\neffect (PHE) in Weyl semimetals based on the semiclassical Boltzmann theory,\nfocusing on the fine structure of the band dispersion. We identified that the\nnegative longitudinal MR and sign change in the PHE occur because of the\nnegative off-diagonal effective-mass with no topological effects or chiral\nanomaly physics. Our results highlight the crucial role of the off-diagonal\neffective-mass, which can cause anomalous galvanomagnetic effects. We propose\nthat the PHE creates a dip in their temperature dependence, which enables the\nexperimental detection of the Weyl point.",
        "positive": "Hausdorff dimension and filling factor: We propose a new hierarchy scheme for the filling factor, a parameter which\ncharacterizes the occurrence of the Fractional Quantum Hall Effect (FQHE). We\nconsider the Hausdorff dimension, $h$, as a parameter for classifying\nfractional spin particles, such that, it is written in terms of the statistics\nof the collective excitations. The number $h$ classifies these excitations with\ndifferent statistics in terms of its homotopy class."
    },
    {
        "anchor": "Gated two-dimensional electron gas in magnetic field: nonlinear versus\n  linear regimes: We study the effect of magnetic field on the properties of a high mobility\ngated two-dimensional electron gas in a field effect transistor with the Hall\nbar geometry. When approaching the current saturation when the drain side of\nthe channel becomes strongly depleted, we see a number of unusual effects\nrelated to the magnetic field induced re-distribution of the electron density\nin the conducting channel. The experimental results obtained in the non-linear\nregime have been interpreted based on the results obtained in the linear regime\nby a simple theoretical model, which describes quite well our observations.",
        "positive": "Unexpected trend of exchange interactions in Fe clusters on Rh(111) and\n  Ru(0001): We use first-principles calculations based on density functional theory to\ninvestigate the magnetic exchange interaction of Fe clusters on Rh(111) and\nRu(0001). We consider dimers, trimers, tetramers, and pentamers of different\nshape in fcc and hcp stacking as well as infinite atomic and biatomic chains.\nFrom the dimer calculations we extract the exchange interaction as a function\nof adatom distance by mapping total energies to a Heisenberg model. The\nnearest-neighbor (NN) exchange constant is about one order of magnitude smaller\nthan reported for other substrates due to the strong hybridization between the\nFe atoms and the partly filled $4d$-band of the surface. We also find a\ntransition from a ferromagnetic NN exchange interaction for Fe dimers on\nRh(111) to an antiferromagnetic one on Ru(0001). The distance-dependent\nexchange coupling displays a RKKY-like oscillatory behavior which is nearly\ninverted for Fe dimers on the Rh(111) surface compared to those on Ru(0001).\nUnexpectedly, for Fe clusters beyond dimers, a complex trend of the magnetic\nground state is observed which alternates between ferro- and antiferromagnetic\nconfigurations depending on cluster size and shape. In view of the exchange\nconstants obtained for dimers, it is surprising that on both surfaces small\ncompact clusters are ferromagnetic while open structures such as linear trimers\nor tetramers become antiferromagnetic. We demonstrate that both vertical and\nlateral structural relaxations of the clusters are crucial in order to\nunderstand this unexpected trend of magnetic order and connected to the\ncompetition of direct ferromagnetic exchange among Fe atoms in the cluster and\nthe hybridization with the substrate."
    },
    {
        "anchor": "Topological photocurrent responses from chiral surface Fermi arcs: The nonlinear optical responses from topological semimetals are crucial in\nboth understanding the fundamental properties of quantum materials and\ndesigning next-generation light-sensors or solar-cells. However, previous work\nwas focusing on the optical effects from bulk states only, disregarding\ntopological surface responses. Here we propose a new (hitherto unknown)\nsurface-only topological photocurrent response from chiral Fermi arcs. Using\nthe ideal topological chiral semimetal RhSi as a representative, we\nquantitatively compute the topologically robust photocurrents from Fermi arcs\non different surfaces. By rigorous crystal symmetry analysis, we demonstrate\nthat Fermi arc photocurrents can be perpendicular to the bulk injection\ncurrents regardless of the choice of materials' surface. We then generalize\nthis finding to all cubic chiral space groups and predict material candidates.\nOur theory reveals a powerful notion where common crystalline-symmetry can be\nused to induce universal topological responses as well as making it possible to\ncompletely disentangle bulk and surface topological responses in many\nconducting material families.",
        "positive": "Adiabatic Transfer of Electrons in Coupled Quantum Dots: We investigate the influence of dissipation on one- and two-qubit rotations\nin coupled semiconductor quantum dots, using a (pseudo) spin-boson model with\nadiabatically varying parameters. For weak dissipation, we solve a master\nequation, compare with direct perturbation theory, and derive an expression for\nthe `fidelity loss' during a simple operation that adiabatically moves an\nelectron between two coupled dots. We discuss the possibility of visualizing\ncoherent quantum oscillations in electron `pump' currents, combining quantum\nadiabaticity and Coulomb blockade. In two-qubit spin-swap operations where the\nrole of intermediate charge states has been discussed recently, we apply our\nformalism to calculate the fidelity loss due to charge tunneling between two\ndots."
    },
    {
        "anchor": "Spin-transfer torque on a single magnetic adatom: We theoretically show how the spin orientation of a single magnetic adatom\ncan be controlled by spin polarized electrons in a scanning tunneling\nmicroscope configuration. The underlying physical mechanism is spin assisted\ninelastic tunneling. By changing the direction of the applied current, the\norientation of the magnetic adatom can be completely reversed on a time scale\nthat ranges from a few nanoseconds to microseconds, depending on bias and\ntemperature. The changes in the adatom magnetization direction are, in turn,\nreflected in the tunneling conductance.",
        "positive": "A quantitative study of spin-flip co-tunneling transport in a quantum\n  dot: We report detailed transport measurements in a quantum dot in a spin-flip\nco-tunneling regime, and a quantitative comparison of the data to microscopic\ntheory. The quantum dot is fabricated by lateral gating of a GaAs/AlGaAs\nheterostructure, and the conductance is measured in the presence of an in-plane\nZeeman field. We focus on the ratio of the nonlinear conductance values at bias\nvoltages exceeding the Zeeman threshold, a regime that permits a spin flip on\nthe dot, to those below the Zeeman threshold, when the spin flip on the dot is\nenergetically forbidden. The data obtained in three different odd-occupation\ndot states show good quantitative agreement with the theory with no adjustable\nparameters. We also compare the theoretical results to the predictions of a\nphenomenological form used previously for the analysis of non-linear\nco-tunneling conductance, specifically the determination of the heterostructure\ng-factor, and find good agreement between the two."
    },
    {
        "anchor": "Coulomb matrix elements of bilayers of confined charge carriers with\n  arbitrary spatial separation: We describe a practical procedure to calculate the Coulomb matrix elements of\n2D spatially separated and confined charge carriers, which are needed for\ndetailed theoretical descriptions of important condensed matter finite systems.\nWe derive an analytical expression, for arbitrary separations, in terms of a\nsingle infinite series and apply a u-type Levin transform in order to\naccelerate the resulting infinite series. This procedure has proven to be\nefficient and accurate. Direct consequences concerning the functional\ndependence of the matrix elements on the separation distance, transition\namplitudes and the diagonalization of a single electron-hole pair in vertically\nstacked parabolic quantum dots are presented.",
        "positive": "Ignition and formation dynamics of a polariton condensate on a\n  semiconductor microcavity pillar: We present an experimental study on the ignition and decay of a polariton\noptical parametric oscillator (OPO) in a semiconductor microcavity pillar. The\ncombination of a continuous wave laser pump, under quasi-phase matching\nconditions, and a non-resonant, 2 ps-long pulse probe allows us to obtain the\nfull dynamics of the system. The arrival of the probe induces a blue-shift in\nthe polariton emission, bringing the OPO process into resonance with the pump,\nwhich triggers the OPO-process. We time-resolve the polariton OPO signal\nemission for more than 1 nanosecond in both real and momentum-space. We fully\ncharacterize the emission of the OPO signal with spectral tomography\ntechniques. Our interpretations are backed up by theoretical simulations based\non the 2D coupled Gross-Pitaevskii equation for excitons and photons."
    },
    {
        "anchor": "Terahertz photoconductivity in bilayer graphene transistors: evidence\n  for tunneling at gate-induced junctions: Photoconductivity of novel materials is the key property of interest for\ndesign of photodetectors, optical modulators, and switches. Despite the\nphotoconductivity of most novel 2d materials has been studied both\ntheoretically and experimentally, the same is not true for 2d p-n junctions\nthat are necessary blocks of most electronic devices. Here, we study the\nsub-terahertz photocoductivity of gapped bilayer graphene with\nelectrically-induced p-n junctions. We find a strong positive contribution from\njunctions to resistance, temperature resistance coefficient and\nphoto-resistivity at cryogenic temperatures T ~ 20 K. The contribution to these\nquantities from junctions exceeds strongly the bulk values at uniform channel\ndoping even at small band gaps ~ 10 meV. We further show that positive junction\nphotoresistance is a hallmark of interband tunneling, and not of intra-band\nthermionic conduction. Our results point to the possibility of creating various\ninterband tunneling devices based on bilayer graphene, including\nsteep-switching transistors and selective sensors.",
        "positive": "Two distinct methods to evaluate graphene relaxation time and mobility\n  in Boltzmann diffusive transport, considering ionized impurity scattering and\n  Thomas-Fermi screening: Boltzmann diffusive transport including relaxation time and mobility in\ngraphene limited by ionized impurity scattering is investigated. The relaxation\ntime is evaluated with two different methods, first one directly use Boltzmann\ntransport equation via scattering matrix, second one is based on scattering\ncross-section. Two methods yield the same relaxation time results for graphene.\nAssume linear Thomas-Fermi screening and a reasonable electron carrier density,\nrelaxation time and mobility can be calculated and plotted, which demonstrates\ngraphene is a very promising high mobility material for ultra fast electronic\ndevice applications."
    },
    {
        "anchor": "Taking stock of the quantum Hall effects: Thirty years on: The quantum Hall effects, discovered about thirty years ago have remained one\nof the most spectacular discoveries in condensed matter physics in the past\ncentury. Those discoveries triggered huge expansion in the field of\nlow-dimensional electronic systems, the area grew at an unprecedented rate and\ncontinues to expand. Novel and challenging observations, be it theoretical or\nexperimental, have been reported since then on a regular basis. Additionally,\nthe effects have inspired physicists to find analogous situations in far-flung\nfields as disparate as string theory or black hole physics.",
        "positive": "Nonlinear electron dynamics in a rippled channel with time-dependent\n  electric field: Quantum Arnol'd diffusion: We study the electron dynamics in a 2D waveguide bounded by a periodically\nrippled surface in the presence of the time-periodic electric field. The main\nattention is paid to a possibility of a weak quantum diffusion along the\ncoupling resonance, that can be associated with the classical Arnol'd\ndiffusion. It was found that quantum diffusion is possible only when the\nperturbation is large enough in order to mix many near-separatrix levels. The\nrate of the quantum diffusion turns out to be less than the corresponding\nclassical one, thus indicating the influence of quantum coherent effects.\nAnother important effect is the dynamical localization of the quantum\ndiffusion, that may be compared with the famous Anderson localization occurring\nin 1D random potentials. Our estimates show that the quantum Arnol'd diffusion\ncan be observed in semi-metal rippled channels, for which the scattering and\ndecoherence times are larger than the saturation time due to the dynamical\nlocalization."
    },
    {
        "anchor": "Barrier tunneling of the Loop-Nodal Semimetal in the Hyperhoneycomb\n  lattice: We theoretically investigate the barrier tunneling in the three-dimensional\nmodel of the hyperhoneycomb lattice, which is a nodal-line semimetal with a\nDirac loop at zero energy. In the presence of a rectangular potential, the\nscattering amplitudes for different injecting states around the nodal loop are\ncalculated, by using analytical treatments of the effective model, as well as\nnumerical simulations of the tight binding model. In the low energy regime,\nstates with remarkable transmissions are only concentrated in a small range\naround the loop plane. When the momentum of the injecting electron is coplanar\nwith the nodal loop, nearly perfect transmissions can occur for a large range\nof injecting azimuthal angles if the potential is not high. For higher\npotential energies, the transmission shows a resonant oscillation with the\npotential, but still with peaks being perfect transmissions that do not decay\nwith the potential width. These robust transports of the loop-nodal semimetal\ncan be approximately explained by a momentum dependent Dirac Hamiltonian.",
        "positive": "Crossover between Thermally Assisted and Pure Quantum Tunneling in\n  Molecular Magnet Mn12-Acetate: The crossover between thermally assisted and pure quantum tunneling has been\nstudied in single crystals of high spin (S=10) uniaxial molecular magnet Mn12\nusing micro-Hall-effect magnetometry. Magnetic hysteresis and relaxation\nexperiments have been used to investigate the energy levels that determine the\nmagnetization reversal as a function of magnetic field and temperature. These\nexperiments demonstrate that the crossover occurs in a narrow (0.1 K) or broad\n(1 K) temperature interval depending on the magnitude of the field transverse\nto the anisotropy axis."
    },
    {
        "anchor": "Plasmon excitations on a single-wall carbon nanotube by external\n  charges: two-dimensional, two-fluid hydrodynamic model: We present a quantization of the hydrodynamic model to describe the\nexcitation of plasmons in a single-walled carbon nanotube by a fast point\ncharge moving near its surface at an arbitrary angle of incidence. Using a\ntwo-dimensional electron gas represented by two interacting fluids, which takes\ninto account the different nature of the sigma and pi electrons, we obtain\nplasmon energies in near-quantitative agreement with experiment. Further, the\nimplemented quantization procedure allows us to study the probability of\nexciting various plasmon modes, as well as the stopping force and energy loss\nspectra of the incident particle.",
        "positive": "Interplay of Wave Localization and Turbulence in Spin Seebeck Effect: One of the most important discoveries in spintronics is the spin Seebeck\neffect (SSE) recently observed in both insulating and (semi-)conducting\nmagnets. However, the very existence of the effect in transverse configuration\nis still a subject of current debates, due to conflicting results reported in\ndifferent experiments. Present understanding of the SSE is mainly based on a\nparticle-like picture with the local equilibrium approximation (LEA), i.e.,\nspatially resolved temperature-field assumed to describe the system. In this\nwork, we abandon the LEA to some extent and develop a wave theory to explain\nthe SSE, by highlighting the interplay between wave localization and\nturbulence. We show that the emerging SSE with a sign change in the\nhigh/low-temperature regions is closely related to the extendedness of the spin\nwave that senses an average temperature of the system. On the one hand,\nubiquitous disorders (or magnetic field gradients) can strongly suppress the\ntransverse spin Seebeck effect (TSSE) due to Anderson (or Wannier-Zeeman)\nspin-wave localization. On the other hand, the competing wave turbulence of\ninteracting magnons tends to delocalize the wave, and thus remarkably revives\nthe TSSE before the magnon self-trapping. Our theory provides a promising route\nto resolve the heated debate on TSSE with a clear experiment scheme to test it\nin future spin caloritronic devices."
    },
    {
        "anchor": "Floquet interface states in illuminated three-dimensional topological\n  insulators: Recent experiments showed that the surface of a three dimensional topological\ninsulator develops gaps in the Floquet-Bloch band spectrum when illuminated\nwith a circularly polarized laser. These Floquet-Bloch bands are characterized\nby non-trivial Chern numbers which only depend on the helicity of the\npolarization of the radiation field. Here we propose a setup consisting of a\npair of counter-rotating lasers, and show that one-dimensional chiral states\nemerge at the interface between the two lasers. These interface states turn out\nto be spin-polarized and may trigger interesting applications in the field of\noptoelectronics and spintronics.",
        "positive": "Localization and absence of Breit-Wigner form for Cauchy random band\n  matrices: We analytically calculate the local density of states for Cauchy random band\nmatrices with strongly fluctuating diagonal elements. The Breit-Wigner form for\nordinary band matrices is replaced by a Levy distribution of index $\\mu=1/2$\nand the characteristic energy scale $\\alpha$ is strongly enhanced as compared\nto the Breit-Wigner width. The unperturbed eigenstates decay according to the\nnon-exponential law $\\propto e^{-\\sqrt{\\alpha t}}$. We analytically determine\nthe localization length by a new method to derive the supersymmetric non-linear\n$\\sigma$ model for this type of band matrices."
    },
    {
        "anchor": "Andreev reflection in two-dimensional topological insulators with either\n  conserved or broken time-reversal symmetry: We investigate Andreev reflection in two-dimensional heterojunctions formed\nby a superconductor in contact with a topological insulator ribbon either\npossessing or breaking time-reversal symmetry. Both classes of topological\ninsulators exhibit perfect Andreev reflection, which is robust against\ndisorder. This is assigned to topologically protected edge states. In the\ntime-reversal symmetric case we show that doping one of the ribbon edges with\nmagnetic impurities suppresses one Andreev channel, while no such suppression\nis seen in the broken symmetry situation. Based on this observation we suggest\na tabletop transport experiment able to distinguish between the two types of\ntopological insulators, which does not involve the direct measurement of the\nmaterial band structure.",
        "positive": "Intrinsic Magnetoconductivity of Non-magnetic Metals: We present a comprehensive study of magnetoconductivity for general\nthree-dimensional non-magnetic metals within the Berry-curvature-corrected\nsemiclassical and Boltzmann framework. We find a new contribution, which is\nintrinsic in the sense that its ratio to the zero-magnetic-field conductivity\nis fully determined by the intrinsic band properties, independent of the\ntransport relaxation time, showing a clear violation of Kohler's rule.\nRemarkably, this contribution can generally be positive for the longitudinal\nconfiguration, providing a new mechanism for the appearance of positive\nmagnetoconductivity under longitudinal configuration besides the chiral anomaly\neffect."
    },
    {
        "anchor": "Enhanced Andreev Tunneling via the Kondo Resonance in a Quantum Dot at\n  Finite Bias: We study the nonequilibrium transport through a quantum dot coupled to normal\nand superconducting leads. We use the modified second-order perturbation theory\nto calculate the differential conductance and the local density of states at\nthe quantum dot. In the strong but finite Coulomb interaction regime, the\ndifferential conductance shows an anomalous peak not at a zero bias voltage but\nat a finite bias voltage. We also observe an additional Kondo resonance besides\nthe normal one in the local density of states, where the former is caused by\nnonequilibrium Andreev tunneling via the normal Kondo resonance. We explain\nthat this specific Andreev tunneling gives rise to the anomalous peak in the\ndifferential conductance. Since the Andreev tunneling via the Kondo resonance\nis suppressed with increasing temperature, the anomalous peak in the\ndifferential conductance disappears at high temperatures.",
        "positive": "Theory of Electric Dipole Spin Resonance in a Parabolic Quantum Well: A theory of Electric Dipole Spin Resonance (EDSR), that is caused by various\nmechanisms of spin-orbit coupling, is developed as applied to free electrons in\na parabolic quantum well. Choosing a parabolic shape of the well has allowed us\nto find explicit expressions for the EDSR intensity and its dependence on the\nmagnetic field direction in terms of the basic parameters of the Hamiltonian.\nBy using these expressions, we have investigated and compared the effect of\nspecific mechanisms of spin orbit (SO) coupling and different polarizations of\nac electric field on the intensity of EDSR. Angular dependences of the EDSR\nintensity are indicative of the relative contributions of the competing\nmechanisms of SO coupling. Our results show that electrical manipulating\nelectron spins in quantum wells is generally highly efficient, especially by an\nin-plane ac electric field."
    },
    {
        "anchor": "Directional emission of light from a nano-optical Yagi-Uda antenna: The plasmon resonance of metal nanoparticles can enhance and direct light\nfrom optical emitters in much the same way that radio frequency (RF) antennas\nenhance and direct the emission from electrical circuits. In the RF regime, a\ntypical antenna design for high directivity is the Yagi-Uda antenna, which\nbasically consists of a one-dimensional array of antenna elements driven by a\nsingle feed element. Here, we present the experimental demonstration of\ndirectional light emission from a nano-optical Yagi-Uda antenna composed of an\narray of appropriately tuned gold nanorods. Our results indicate that\nnano-optical antenna arrays are a simple but efficient tool for the spatial\ncontrol of light emission.",
        "positive": "Order O(1) algorithm for first-principles transient current through open\n  quantum systems: In the study the response time of ultrafast transistor and peak transient\ncurrent to prevent melt down of nano-chips, the first principles transient\ncurrent calculation plays an essential role in nanoelectronics. The first\nprinciples calculation of transient current through nano-devices for a period\nof time T is known to be extremely time consuming with the best scaling TN^3\nwhere N is the dimension of the device. In this work, we provide an order O(1)\nalgorithm that reduces the computational complexity to T^0 N^3 for large\nsystems. Benchmark calculation has been done on graphene nanoribbons with N =\n10^4 confirming the O(1) scaling. This breakthrough allows us to tackle many\nlarge scale transient problems including magnetic tunneling junctions and\nferroelectric tunneling junctions that cannot be touched before."
    },
    {
        "anchor": "Optomechanical response of a non-linear mechanical resonator: We investigate theoretically in detail the non-linear effects in the response\nof an optical/microwave cavity coupled to a Duffing mechanical resonator. The\ncavity is driven by a laser at a red or blue mechanical subband, and a probe\nlaser measures the reflection close to the cavity resonance. Under these\nconditions, we find that the cavity exhibits optomechanically induced\nreflection (OMIR) or absorption (OMIA) and investigate the optomechanical\nresponse in the limit of non-linear driving of the mechanics. Similar to linear\nmechanical drive, an overcoupled cavity the red-sideband drive may lead to both\nOMIA and OMIR depending on the strength of the drive, whereas the blue-sideband\ndrive only leads to OMIR. The dynamics of the phase of the mechanical resonator\nleads to the difference between the shapes of the response of the cavity and\nthe amplitude response of the driven Duffing oscillator, for example, at weak\nred-sideband drive the OMIA dip has no inflection point. We also verify that\nmechanical non-linearities beyond Duffing model have little effect on the size\nof the OMIA dip though they affect the width of the dip.",
        "positive": "Quantum phase transitions in effective spin-ladder models for graphene\n  zigzag nanoribbons: We examine the magnetic correlations in quantum spin models that were derived\nrecently as effective low-energy theories for electronic correlation effects on\nthe edge states of graphene nanoribbons. For this purpose, we employ quantum\nMonte Carlo simulations to access the large-distance properties, accounting for\nquantum fluctuations beyond mean-field-theory approaches to edge magnetism. For\ncertain chiral nanoribbons, antiferromagnetic inter-edge couplings were\npreviously found to induce a gapped quantum disordered ground state of the\neffective spin model. We find that the extended nature of the intra-edge\ncouplings in the effective spin model for zigzag nanoribbons leads to a quantum\nphase transition at a large, finite value of the inter-edge coupling. This\nquantum critical point separates the quantum disordered region from a gapless\nphase of stable edge magnetism at weak intra-edge coupling, which includes the\nground states of spin-ladder models for wide zigzag nanoribbons. To study the\nquantum critical behavior, the effective spin model can be related to a model\nof two antiferromagnetically coupled Haldane-Shastry spin-half chains with\nlong-ranged ferromagnetic intra-chain couplings. The results for the critical\nexponents are compared also to several recent renormalization group\ncalculations for related long-ranged interacting quantum systems."
    },
    {
        "anchor": "Topological Edge Conduction Induced by Strong Anisotropic Exchange\n  Interactions: We predict that an interplay between isotropic and anisotropic exchange\ninteractions in a honeycomb lattice structure can lead to topological edge\nconduction when the anisotropic interaction is at least twice the strength of\nthe isotropic interaction. For materials like Na$_2$IrO$_3$, such a strong\nanisotropic exchange interaction simultaneously induces a zigzag type of\nantiferromagnetic order that breaks the time-reversal symmetry of the\ntopological edge conductor. We show that the electronic transport in such\ntopological conductors will exhibit a quantized Hall conductance without any\nexternal magnetic field when the Fermi energy lies within a particular energy\nrange.",
        "positive": "Derivative relation for thermopower in the quantum Hall regime: Recently, Tieke et al (to be published in PRL) have observed the relation\nS_{yx} = alpha B dS_{xx}/dB for the components of the thermopower tensor in the\nquantum Hall regime, where alpha is a constant and B is the magnetic field.\nSimon and Halperin (PRL 73, 3278 (1994)) have suggested that an analogous\nrelation observed for the resistivity tensor R_{xx} = \\alpha B dR_{xy}/dB can\nbe explained with a model of classical transport in an inhomogeneous medium\nwhere the local Hall resistivity is a function of position and the local\ndissipative resistivity is a small constant. In the present paper, we show that\nthis new thermopower relation can be explained with a similar model."
    },
    {
        "anchor": "Spin-orbit coupling in ballistic carbon nanotubes: This paper has been withdrawn.",
        "positive": "Strong Coupling Fixed Points of Current Interactions and Disordered\n  Fermions in 2D: The all-orders beta function is used to study disordered Dirac fermions in\n2D. The generic strong coupling fixed `points' of anisotropic current-current\ninteractions at large distances are actually isotropic manifolds corresponding\nto subalgebras of the maximal current algebra at short distances. The IR\ntheories are argued to be current algebra cosets. We illustrate this with the\nsimple example of anisotropic su(2), which is the physics of\nKosterlitz-Thouless transitions. We work out the phase diagram for the\nChalker-Coddington network model which is in the universality class of the\ninteger Quantum Hall transition. One massless phase is in the universality\nclass of dense polymers."
    },
    {
        "anchor": "Electronic, optical, and thermodynamic properties of borophene from\n  first-principle calculations: Borophene (two-dimensional boron sheet) is a new type of two-dimensional\nmaterial, which was recently grown successfully on single crystal Ag\nsubstrates. In this paper, we investigate the electronic structure and bonding\ncharacteristics of borophene by first-principle calculations. The band\nstructure of borophene shows highly anisotropic metallic behaviour. The\nobtained optical properties of borophene exhibit strong anisotropy as well. The\ncombination of high optical transparency and high electrical conductivity in\nborophene makes it a promising candidate for future design of transparent\nconductors used in photovoltaics. Finally, the thermodynamic properties are\ninvestigated based on the phonon properties.",
        "positive": "Left-handed Ferromagnet: The dynamics of the total magnetization in metallic ferromagnet is studied\ntheoretically taking into account the relativistic spin-orbit interaction. It\nis found that its quantum dynamics is seriously influenced by the band\ncrossings near the Fermi energy, and sometimes the direction of the precession\ncan be reversed from what expected from the commutation relation\n$[S^{x},S^{y}]= i\\hbar S^{z}$ ($h = 2\\pi \\hbar$: Planck constant), i.e., the\nleft-handed ferromagnet can be realized."
    },
    {
        "anchor": "Excitation of a Si/SiGe quantum dot using an on-chip microwave antenna: We report transport measurements on a Si/SiGe quantum dot subject to\nmicrowave excitation via an on-chip antenna. The response shows signatures of\nphoton-assisted tunneling and only a small effect on charge stability. We also\nexplore the use of a d.c. current applied to the antenna for generating\ntunable, local magnetic field gradients and put bounds on the achievable field\ngradients, limited by heating of the reservoirs.",
        "positive": "On the role of electron-phonon interaction in the resistance anisotropy\n  of two-dimensional electrons in GaAs heterostructures: A contribution of the electron-phonon interaction into the energy of a\nunidirectional charge ordered state (stripe phase) of two-dimensional electrons\nin GaAs heterostructures is analyzed. The dependence of the energy on the\ndirection of the electron density modulation is calculated. It is shown that in\nelectrons layers situated close to the (001) surface the interference between\nthe piezoelectric and the deformation potential interaction causes a\npreferential orientation of the stripes along the [110] axis."
    },
    {
        "anchor": "Selective nonresonant excitation of vibrational modes in suspended\n  graphene via vibron-plasmon interaction: We theoretically study a doped graphene ribbon suspended over a trench and\nsubject to an ac-electrical field polarized perpendicularly to the graphene\nplane. In such a system, the external ac-field is coupled to the relatively\nslow mechanical vibrations via plasmonic oscillations in the isolated graphene\nsheet. We show that the electrical field generates an effective pumping of the\nmechanical modes. It is demonstrated that in the case of underdamped plasma\noscillation, a peculiar kind of geometrical resonance of the mechanical and\nplasma oscillations appear. Namely the efficiency of pumping significantly\nincreases when the wave number of the mechanical mode is in close agreement\nwith the wave number of the plasma waves. The intensity of the pumping\nincreases with the wave number of the mode. This phenomenon allows selective\nactuation of different mechanical modes although the driving field is\nhomogeneous.",
        "positive": "Anharmonicity and asymmetry of Landau levels for a two-dimensional\n  electron gas: We calculate the density of states of a two dimensional electron gas located\nat the interface of a GaAlAs/GaAs heterojunction. The disorder potential which\nis generally created by a single doping layer behind a spacer, is here enhanced\nby the presence of a second delta doped layer of scatterers which can be\nrepulsive or attractive impurities. We have calculated the density of states by\nmeans of the Klauder's approximation, in the presence of a magnetic field of\narbitrary strength. At low field either band tails or impurity bands are\nobserved for attractive potentials, depending on the impurity concentration. At\nhigher field, impurity bands are observed for both repulsive and attractive\npotentials. We discuss the effect of such an asymmetrical density of states on\nthe transport properties in the quantum Hall effect regime."
    },
    {
        "anchor": "Unusual non-equilibrium behavior of cupric oxide nanoparticles: We report studies on temperature, field and time dependence of magnetization\non cupric oxide nanoparticles of sizes 9 nm, 13 nm and 16 nm. The nanoparticles\nshow unusual features in comparison to other antiferromagnetic nanoparticle\nsystems. The field cooled (FC) and zero field cooled (ZFC) magnetization curves\nbifurcate well above the Neel temperature and the usual peak in the ZFC\nmagnetization curve is absent.\n  The system does not show any memory effects which is in sharp contrast to the\nusual behavior shown by other antiferromagnetic nanoparticles. It turns out\nthat the nature of CuO nanoparticles is very strange and is neither\nsuperparamagnetic nor spin glass-like .",
        "positive": "Effects of asymmetry in strongly coupled spin vortex pairs: Effects of magnetic asymmetry on strongly coupled spin-vortex pairs with\nparallel core polarization and antiparallel chirality in synthetic nanomagnets\nare investigated. This includes vortex-core length asymmetry, biasing field\nasymmetry, and pinning of one of the two vortex cores. Our experimental\nobservations as well as analytical and micromagnetic modeling show how magnetic\nasymmetry can be used to differentiate magneto-resistively otherwise degenerate\nmultiple stable states of a vortex pair. These results expand the knowledge\nbase for spin vortex arrays in nanostructures and should be useful in light of\nthe recent proposals on coding information into multiple topological spin\nstates, such as single and multiple vortex core/chirality states."
    },
    {
        "anchor": "Optical conductivity of tilted higher pseudospin Dirac-Weyl cones: We investigate the finite-frequency optical response of systems described at\nlow energies by Dirac-Weyl Hamiltonians with higher pseudospin $\\mathcal{S}$\nvalues. In particular, we examine the situation where a tilting term is applied\nin the Hamiltonian, which results in tilting of the Dirac electronic band\nstructure. We calculate and discuss the optical conductivity for the cases\n$\\mathcal{S}=1$, $3/2$, and $2$, in both two and three dimensions in order to\ndemonstrate the expected signatures in the optical response. We examine both\nundertilted (type I) and overtilted (type II) as well as the critically-tilted\ncase (type III). Along with the well-known case of $\\mathcal{S} =1/2$, a\npattern emerges for any $\\mathcal{S}$. We note that in situations with multiple\nnested cones, such as happens for $\\mathcal{S}>1$, the possibility of having\none cone being type I while the other is type II allows for more rich\nvariations in the optical signature, which we will label as type IV behavior.\nWe also comment on the presence of optical sum rules in the presence of\ntilting. Finally, we discuss tilting in the $\\alpha$-T$_3$ model in two\ndimensions, which is a hybrid of the $\\mathcal{S}=1/2$ (honeycomb lattice) and\n$\\mathcal{S}=1$ (dice or T$_3$ lattice) model with a variable Berry's phase. We\ncontrast this model's conductivity with that of $\\mathcal{S}=3/2$ and\n$\\mathcal{S}=2$ as the resultant optical response has some similarities,\nalthough there are clear distinguishing features between the these cases.",
        "positive": "Metastable domain wall dynamics in magnetic nanowires: We study the formation and control of metastable states of pairs of domain\nwalls in cylindrical nanowires of small diameter where the transverse walls are\nthe lower energy state. We show that these pairs form bound states under\ncertain conditions, with a lifetime as long as 200ns, and are stabilized by the\ninfluence of a spin polarized current. Their stability is analyzed with a model\nbased on the magnetostatic interaction and by 3D micromagnetic simulations. The\napparition of bound states could hinder the operation of devices."
    },
    {
        "anchor": "Reversible Metal-Semiconductor Transition of ssDNA-Decorated\n  Single-Walled Carbon Nanotubes: A field effect transistor (FET) measurement of a SWNT shows a transition from\na metallic one to a p-type semiconductor after helical wrapping of DNA. Water\nis found to be critical to activate this metal-semiconductor transition in the\nSWNT-ssDNA hybrid. Raman spectroscopy confirms the same change in electrical\nbehavior. According to our ab initio calculations, a band gap can open up in a\nmetallic SWNT with wrapped ssDNA in the presence of water molecules due to\ncharge transfer.",
        "positive": "Thermoelectric response of fractional quantized Hall and re-entrant\n  insulating states in the N=1 Landau level: Detailed measurements of the longitudinal thermopower of two-dimensional\nelectrons in the first excited Landau level are reported. Clear signatures of\nnumerous fractional quantized Hall states, including those at $\\nu = 5/2$ and\n7/3, are observed in the magnetic field and temperature dependence of the\nthermopower. An abrupt collapse of the thermopower is observed below about $T=\n40$ mK at those filling factors where re-entrant insulating electronic states\nhave been observed in conventional resistive transport studies. The thermopower\nobserved at $\\nu = 5/2$ is discussed in the context of recent theories which\nincorporate non-abelian quasiparticle exchange statistics."
    },
    {
        "anchor": "Exotic Multifractal Conductance Fluctuations in Graphene: In quantum systems, signatures of multifractality are rare. They have been\nfound only in the multiscaling of eigenfunctions at critical points. Here we\ndemonstrate multifractality in the magnetic-field-induced universal conductance\nfluctuations of the conductance in a quantum condensed-matter system, namely,\nhigh-mobility single-layer graphene field-effect transistors. This\nmultifractality decreases as the temperature increases or as doping moves the\nsystem away from the Dirac point. Our measurements and analysis present\nevidence for an incipient Anderson-localization near the Dirac point as the\nmost plausible cause for this multifractality. Our experiments suggest that\nmultifractality in the scaling behaviour of local eigenfunctions are reflected\nin macroscopic transport coefficients. We conjecture that an incipient\nAnderson-localization transition may be the origin of this multifractality. It\nis possible that multifractality is ubiquitous in transport properties of\nlow-dimensional systems. Indeed, our work suggests that we should look for\nmultifractality in transport in other low-dimensional quantum condensed-matter\nsystems.",
        "positive": "Electric Current Focusing Efficiency in Graphene Electric Lens: In present work, we theoretically study the electron wave's focusing\nphenomenon in a single layered graphene pn junction(PNJ) and obtain the\nelectric current density distribution of graphene PNJ, which is in good\nagreement with the qualitative result in previous numerical calculations\n[Science, 315, 1252 (2007)]. In addition, we find that for symmetric PNJ, 1/4\nof total electric current radiated from source electrode can be collected by\ndrain electrode. Furthermore, this ratio reduces to 3/16 in a symmetric\ngraphene npn junction. Our results obtained by present analytical method\nprovide a general design rule for electric lens based on negative refractory\nindex systems."
    },
    {
        "anchor": "Thermoelectric and thermal transport in bilayer graphene systems: We numerically study the disorder effect on the thermoelectric and thermal\ntransport for bilayer graphene under a strong perpendicular magnetic field. In\nthe unbiased case, we find that the thermoelectric transport has similar\nproperties as in the monolayer graphene, i.e., the Nernst signal has a peak at\nthe central Landau level (LL) with the value of the order of $k_B/e$ and\nchanges sign near other LLs while the thermopower has an opposite behavior. We\nattribute this to the coexistence of particle and hole LLs around the Dirac\npoint. When a finite interlayer bias is applied and a band gap is opened, it is\nfound that the transport properties are consistent with those of a band\ninsulator. We further study the thermal transport from electronic origins and\nverify the validity of the generalized Weidemann-Franz law.",
        "positive": "Quantum Diagrammatic Theory of the Extrinsic Spin Hall Effect in\n  Graphene: We present a rigorous microscopic theory of the extrinsic spin Hall effect in\ndisordered graphene based on a nonperturbative quantum diagrammatic treatment\nincorporating skew scattering and anomalous---impurity\nconcentration-independent---quantum corrections on equal footing. The leading\nskew scattering contribution to the spin Hall conductivity is shown to\nquantitatively agree with Boltzmann transport theory over a wide range of\nparameters. Our self-consistent approach---where all topologically equivalent\nnoncrossing diagrams are resummed---unveils that the skewness generated by\nspin--orbit-active impurities deeply influences the anomalous component of the\nspin Hall conductivity, even in the weak scattering regime. This seemingly\ncounterintuitive result is explained by the rich sublattice structure of\nscattering potentials in graphene, for which traditional Gaussian disorder\napproximations fail to capture the intricate correlations between skew\nscattering and side jumps generated through diffusion. Finally, we assess the\nrole of quantum interference corrections by evaluating an important subclass of\ncrossing diagrams recently considered in the context of the anomalous Hall\neffect, the $X$ and $\\Psi$ diagrams [Ado et al., EPL 111, 37004 (2015)]. We\nshow that $\\Psi$ diagrams---encoding quantum coherent skew scattering---display\na strong Fermi energy dependence, dominating the anomalous spin Hall component\naway from the Dirac point. Our findings have direct implications for nonlocal\ntransport experiments in spin--orbit-coupled graphene systems."
    },
    {
        "anchor": "Double Point Contact in the k=3 Read-Rezayi State: We compute the dependence of the tunneling current in a double point contact\nin the k=3 Read-Rezayi state (which is conjectured to describe an\nincompressible quantum hall fluid at filling fraction nu=12/5) on voltage,\nseparation between the two contacts, and temperature. Using the tunneling\nhamiltonian of cond-mat/0607431, we show that the effect of quasiholes in the\nbulk region between the two contacts is simply an overall constant multiplying\nthe interference term. This is the same effect as found for the differential\nconductivity in cond-mat/0601242; the difference is that we do an actual edge\ntheory calculation and compute the full current-voltage curve at weak\ntunneling.",
        "positive": "Power and linewidth of propagating and localized modes in nanocontact\n  spin-torque oscillators: Integrated power and linewidth of a propagating and a self-localized spin\nwave modes excited by spin-polarized current in an obliquely magnetized\nmagnetic nanocontact are studied experimentally as functions of the angle\n$\\theta_e$ between the external bias magnetic field and the nanocontact plane.\nIt is found that the power of the propagating mode monotonically increases with\n$\\theta_e$, while the power of the self-localized mode has a broad maximum near\n$\\theta_e = 40$ deg, and exponentially vanishes near the critical angle\n$\\theta_e = 58$ deg, at which the localized mode disappears. The linewidth of\nthe propagating mode in the interval of angles $58<\\theta_e<90$ deg, where only\nthis mode is excited, is adequtely described by the existing theory, while in\nthe angular interval where both modes can exist the observed linewidth of both\nmodes is substantially broadened due to the telegraph switching between the\nmodes. Numetical simulations and an approximate analytical model give good\nsemi-quantitative description of the observed results."
    },
    {
        "anchor": "Stretchable persistent spin helices in GaAs quantum wells: The Rashba and Dresselhaus spin-orbit (SO) interactions in 2D electron gases\nact as effective magnetic fields with momentum-dependent directions, which\ncause spin decay as the spins undergo arbitrary precessions about these\nrandomly-oriented SO fields due to momentum scattering. Theoretically and\nexperimentally, it has been established that by fine-tuning the Rashba $\\alpha$\nand Dresselhaus $\\beta$ couplings to equal $\\it{fixed}$ strengths\n$\\alpha=\\beta$, the total SO field becomes unidirectional thus rendering the\nelectron spins immune to dephasing due to momentum scattering. A robust\npersistent spin helix (PSH) has already been experimentally realized at this\nsingular point $\\alpha=\\beta$. Here we employ the suppression of weak\nantilocalization as a sensitive detector for matched SO fields together with a\ntechnique that allows for independent electrical control over the SO couplings\nvia top gate voltage $V_T$ and back gate voltage $V_B$. We demonstrate for the\nfirst time the gate control of $\\beta$ and the $\\it{continuous\\,locking}$ of\nthe SO fields at $\\alpha=\\beta$, i.e., we are able to vary both $\\alpha$ and\n$\\beta$ controllably and continuously with $V_T$ and $V_B$, while keeping them\nlocked at equal strengths. This makes possible a new concept: \"stretchable\nPSHs\", i.e., helical spin patterns with continuously variable pitches $P$ over\na wide parameter range. The extracted spin-diffusion lengths and decay times as\na function of $\\alpha/\\beta$ show a significant enhancement near\n$\\alpha/\\beta=1$. Since within the continuous-locking regime quantum transport\nis diffusive (2D) for charge while ballistic (1D) for spin and thus amenable to\ncoherent spin control, stretchable PSHs could provide the platform for the much\nheralded long-distance communication $\\sim 8 - 25$ $\\mu$m between solid-state\nspin qubits.",
        "positive": "Cryogenic on-chip multiplexer for the study of quantum transport in 256\n  split-gate devices: We present a multiplexing scheme for the measurement of large numbers of\nmesoscopic devices in cryogenic systems. The multiplexer is used to contact an\narray of 256 split gates on a GaAs/AlGaAs heterostructure, in which each split\ngate can be measured individually. The low-temperature conductance of\nsplit-gate devices is governed by quantum mechanics, leading to the appearance\nof conductance plateaux at intervals of 2e^2/h. A fabrication-limited yield of\n94% is achieved for the array, and a \"quantum yield\" is also defined, to\naccount for disorder affecting the quantum behaviour of the devices. The\nquantum yield rose from 55% to 86% after illuminating the sample, explained by\nthe corresponding increase in carrier density and mobility of the\ntwo-dimensional electron gas. The multiplexer is a scalable architecture, and\ncan be extended to other forms of mesoscopic devices. It overcomes previous\nlimits on the number of devices that can be fabricated on a single chip due to\nthe number of electrical contacts available, without the need to alter existing\nexperimental set ups."
    },
    {
        "anchor": "Exciton Liquid in Coupled Quantum Wells: Excitons in semiconductors may form correlated phases at low temperatures. We\nreport the observation of an exciton liquid in GaAs/AlGaAs coupled quantum\nwells. Above a critical density and below a critical temperature the\nphotogenerated electrons and holes separate into two phases, an electron-hole\nplasma and an exciton liquid, with a clear sharp boundary between them. The two\nphases are characterized by distinct photoluminescence spectra and by different\nelectrical conductance. The liquid phase is formed by the repulsive interaction\nbetween the dipolar excitons, and exhibits a short range order, which is\nmanifested in the photoluminescence lineshape.",
        "positive": "Strong, Ultra-narrow Peaks of Longitudinal and Hall Resistances in the\n  Regime of Breakdown of the Quantum Hall Effect: With unusually slow and high-resolution sweeps of magnetic field, strong,\nultra-narrow (width down to $100 {\\rm \\mu T}$) resistance peaks are observed in\nthe regime of breakdown of the quantum Hall effect. The peaks are dependent on\nthe directions and even the history of magnetic field sweeps, indicating the\ninvolvement of a very slow physical process. Such a process and the sharp peaks\nare, however, not predicted by existing theories. We also find a clear\nconnection between the resistance peaks and nuclear spin polarization."
    },
    {
        "anchor": "Density inhomogeneity driven percolation metal-insulator transition and\n  dimensional crossover in graphene nanoribbons: Transport in graphene nanoribbons with an energy gap in the spectrum is\nconsidered in the presence of random charged impurity centers. At low carrier\ndensity, we predict and establish that the system exhibits a density\ninhomogeneity driven two dimensional metal-insulator transition that is in the\npercolation universality class. For very narrow graphene nanoribbons (with\nwidths smaller than the disorder induced length-scale), we predict that there\nshould be a dimensional crossover to the 1D percolation universality class with\nobservable signatures in the transport gap. In addition, there should be a\ncrossover to the Boltzmann transport regime at high carrier densities. The\nmeasured conductivity exponent and the critical density are consistent with\nthis percolation transition scenario.",
        "positive": "Electron-phonon interaction in thin copper and gold films: We have studied the electron-phonon (e-p) interaction in thin Cu and Au films\nat sub-Kelvin temperatures with the help of the hot electron effect, using\nsymmetric normal metal-insulator-superconductor tunnel junction pairs as\nthermometers. By Joule heating the electron gas and measuring the electron and\nthe lattice temperatures simultaneously, we show that the electron-phonon\nscattering rate follows a $T^{4}$ temperature dependence in both metals. The\nresult is in accordance with the theory of e-p scattering in disordered films\nwith vibrating boudaries and impurities, in contrast to the $T^{3}$-law\nexpected for pure samples, and $T^{2}$-law for static disorder."
    },
    {
        "anchor": "Giant off-resonance resistance spike related phenomena in irradiated\n  ultraclean two-dimensional electron systems: We report on theoretical studies of a recently discovered strong\nradiation-induced magnetoresistance spike obtained in ultraclean\ntwo-dimensional electron systems at low temperatures. The most striking feature\nof this spike is that it shows up on the second harmonic of the cyclotron\nresonance and with an amplitude that can reach an order of magnitude larger\nthan the radiation-induced resistance oscillations. We apply the\nradiation-driven electron orbits model in the ultraclean scenario. Accordingly,\nwe calculate the elastic scattering rate (charged impurity) which will define\nthe unexpected resonance spike position. We also obtain the inelastic\nscattering rate (phonon damping), that will be responsible of the large spike\namplitude. We present a microscopical model to explain the dependence of the\nLandau level width on the magnetic field for ultraclean samples. We find that\nthis dependence explains the experimental shift of the resistance oscillations\nwith respect to the magnetic field found in this kind of samples. We study also\nrecent results on the influence of an in-plane magnetic field on the spike. We\nare able to reconcile the obtained different experimental response of both\nspike and resistance oscillations versus an increasing in-plane field. The same\nmodel on the variation of the LL width, allows us to explain such surprising\nresults based in the increasing disorder in the sample caused by the in-planed\nmagnetic field. Calculated results are in good agreement with experiments.\nThese results would be of special interest in nanophotonics; they could lead to\nthe design of novel ultrasensitive microwave detectors.",
        "positive": "Gauge-invariant cutoff for Dirac electron systems with a vector\n  potential: The continuum Dirac model with an unbounded energy spectrum is widely used to\ndescribe low-energy states in various electron systems, such as graphene,\ntopological insulators, and Weyl semimetals. However, if it is applied to\nanalyze the electromagnetic response of electrons to a vector potential, we\noften find an unphysical result that breaks gauge invariance. This is an\nartifact caused by an energy or wavenumber cutoff, which is used to avoid\ndivergence of the response. Here, we propose a modified energy cutoff procedure\nthat preserves the gauge invariance. We use this procedure to calculate the\nresponse functions in a two-dimensional massless Dirac electron system. It is\nshown that the resulting functions properly describe the electromagnetic\nresponse in a gauge-invariant manner."
    },
    {
        "anchor": "Phonon-assisted resonant tunneling through a triple-quantum-dot: a\n  phonon-signal detector: We study the effect of electron-phonon interaction on current and\nzero-frequency shot noise in resonant tunneling through a series\ntriple-quantum-dot coupling to a local phonon mode by means of a\nnonperturbative mapping technique along with the Green function formulation. By\nfixing the energy difference between the first two quantum dots to be equal to\nphonon frequency and sweeping the level of the third quantum dot, we find a\nlargely enhanced current spectrum due to phonon effect, and in particular we\npredict current peaks corresponding to phonon-absorption and -emission assisted\nresonant tunneling processes, which shows that this system can be acted as a\nsensitive phonon-signal detector or as a cascade phonon generator.",
        "positive": "Determining the Rashba parameter from the bilinear magnetoresistance\n  response in a two-dimensional electron gas: Two-dimensional (2D) Rashba systems have been intensively studied in the last\ndecade due to their unconventional physics, tunability capabilities, and\npotential for spin-charge interconversion when compared to conventional heavy\nmetals. With the advent of a new generation of spin-based logic and memory\ndevices, the search for Rashba systems with more robust and larger conversion\nefficiencies is expanding. Conventionally, demanding techniques such as angle-\nand spin-resolved photoemission spectroscopy are required to determine the\nRashba parameter $\\alpha_{R}$ that characterizes these systems. Here, we\nintroduce a simple method that allows a quantitative extraction of\n$\\alpha_{R}$, through the analysis of the bilinear response of angle-dependent\nmagnetotransport experiments. This method is based on the modulation of the\nRashba-split bands under a rotating in-plane magnetic field. We show that our\nmethod is able to correctly yield the value of $\\alpha_{R}$ for a wide range of\nFermi energies in the 2D electron gas at the LaAlO$_{3}$/SrTiO$_{3}$ interface.\nBy applying a gate voltage, we observe a maximum $\\alpha_{R}$ in the region of\nthe band structure where interband effects maximize the Rashba effect,\nconsistently with theoretical predictions."
    },
    {
        "anchor": "Large spin to charge conversion in topological superconductor\n  \\b{eta}-PdBi2 at room temperature: \\b{eta}-PdBi2 has attracted much attention for its prospective ability to\npossess simultaneously topological surface and superconducting states due to\nits unprecedented spin-orbit interaction (SOC). Whereas most works have focused\nsolely on investigating its topological surface states, the coupling between\nspin and charge degrees of freedom in this class of quantum material remains\nunexplored. Here we first report a study of spin-to-charge conversion in a\n\\b{eta}-PdBi2 ultrathin film grown by molecular beam epitaxy, utilizing a spin\npumping technique to perform inverse spin Hall effect measurements. We find\nthat the room temperature spin Hall angle of Fe/\\b{eta}-PdBi2,\n{\\theta}_SH=0.037. This value is one order of magnitude larger than that of\nreported conventional superconductors, and is comparable to that of the best\nSOC metals and topological insulators. Our results provide an avenue for\ndeveloping superconductor-based spintronic applications.",
        "positive": "Universal vortex formation in rotating traps with bosons and fermions: When a system consisting of many interacting particles is set rotating, it\nmay form vortices. This is familiar to us from every-day life: you can observe\nvortices while stirring your coffee or watching a hurricane. In the world of\nquantum mechanics, famous examples of vortices are superconducting films and\nrotating bosonic $^4$He or fermionic $^3$He liquids. Vortices are also observed\nin rotating Bose-Einstein condensates in atomic traps and are predicted to\nexist for paired fermionic atoms. Here we show that the rotation of trapped\nparticles with a repulsive interaction leads to a similar vortex formation,\nregardless of whether the particles are bosons or (unpaired) fermions. The\nexact, quantum mechanical many-particle wave function provides evidence that in\nfact, the mechanism of this vortex formation is the same for boson and fermion\nsystems."
    },
    {
        "anchor": "General nonlinear Hall current in magnetic insulators beyond the quantum\n  anomalous Hall effect: Can a generic magnetic insulator exhibit a Hall current? The quantum\nanomalous Hall effect (QAHE) is one example of an insulating bulk carrying a\nquantized Hall conductivity and other insulators (with zero Chern number)\npresent zero Hall conductance in the linear response regime. Here, we find that\na general magnetic insulator possesses a nonlinear Hall conductivity quadratic\nto the electric field if the system breaks inversion symmetry. This\nconductivity originates from an induced orbital magnetization due to virtual\ninterband transitions. We identify three contributions to the wavepacket\nmotion, a velocity shift, a positional shift, and a Berry curvature\nrenormalization. In contrast to the crystalline solid, we find that this\nnonlinear Hall conductivity vanishes for Landau levels of a 2D electron gas,\nindicating a fundamental difference between the QAHE and the Integer quantum\nHall effect.",
        "positive": "Rashba spin-orbit coupling and spin precession in carbon nanotubes: The Rashba spin-orbit coupling in carbon nanotubes and its effect on\nspin-dependent transport properties are analyzed theoretically. We focus on\nclean non-interacting nanotubes with tunable number of subbands $N$. The\npeculiar band structure is shown to allow in principle for Datta-Das\noscillatory behavior in the tunneling magnetoresistance as a function of gate\nvoltage, despite the presence of multiple bands. We discuss the conditions for\nobserving Datta-Das oscillations in carbon nanotubes."
    },
    {
        "anchor": "Bilinear magnetoresistance in HgTe topological insulator: opposite signs\n  at opposite interfaces demonstrated by gate control: Spin-orbit effects appearing in topological insulators (TI) and at Rashba\ninterfaces are currently revolutionizing how we can manipulate spins and have\nled to several newly discovered effects, from spin-charge interconversion and\nspin-orbit torques to novel magnetoresistance phenomena. In particular, a\npuzzling magnetoresistance has been evidenced, bilinear in electric and\nmagnetic fields. Here, we report the observation of bilinear magnetoresistance\n(BMR) in strained HgTe, a prototypical TI. We show that both the amplitude and\nsign of this BMR can be tuned by controlling, with an electric gate, the\nrelative proportions of the opposite contributions of opposite surfaces. At\nmagnetic fields of 1 T, the magnetoresistance is of the order of 1 \\% and has a\nlarger figure of merit than previously measured TIs. We propose a theoretical\nmodel giving a quantitative account of our experimental data. This phenomenon,\nunique to TI, offers novel opportunities to tune their electrical response for\nspintronics.",
        "positive": "Coulomb effects on the transport properties of quantum dots in strong\n  magnetic field: We investigate the transport properties of quantum dots placed in strong\nmagnetic field using a quantum-mechanical ' approach based on the 2D\ntight-binding Hamiltonian with direct Coulomb interaction and the\nLandauer-B\\\"{u}ttiker (LB) formalism. The electronic transmittance and the Hall\nresistance show Coulomb oscillations and also prove multiple addition\nprocesses. We identify this feature as the 'bunching' of electrons observed in\nrecent experiments and give an elementary explanation in terms of spectral\ncharacteristics of the dot. The spatial distribution of the added electrons may\ndistinguish between edge and bulk states and it has specific features for\nbunched electrons. The dependence of the charging energy on the number of\nelectrons is discussed for strong and vanishing magnetic field. The crossover\nfrom the tunneling to quantum Hall regime is analyzed in terms of dot-lead\ncoupling."
    },
    {
        "anchor": "Non-Hermitian boundary spectral winding: Spectral winding of complex eigenenergies represents a topological aspect\nunique in non-Hermitian systems, which vanishes in one-dimensional (1D) systems\nunder the open boundary conditions (OBC). In this work, we discover a boundary\nspectral winding in two-dimensional non-Hermitian systems under the OBC,\noriginating from the interplay between Hermitian boundary localization and\nnon-Hermitian non-reciprocal pumping. Such a nontrivial boundary topology is\ndemonstrated in a non-Hermitian breathing Kagome model with a triangle\ngeometry, whose 1D boundary mimics a 1D non-Hermitian system under the periodic\nboundary conditions with nontrivial spectral winding. In a trapezoidal\ngeometry, such a boundary spectral winding can even co-exist with corner\naccumulation of edge states, instead of extended ones along 1D boundary of a\ntriangle geometry. An OBC type of hybrid skin-topological effect may also\nemerge in a trapezoidal geometry, provided the boundary spectral winding\ncompletely vanishes. By studying the Green's function, we unveil that the\nboundary spectral winding can be detected from a topological response of the\nsystem to a local driving field, offering a realistic method to extract the\nnontrivial boundary topology for experimental studies.",
        "positive": "Intrinsic graphene field effect transistor on amorphous carbon films: Fabrication of graphene field effect transistor is described which uses an\nintrinsic graphene on the surface of as deposited hydrogenated amorphous carbon\nfilms. Ambipolar characteristic has been demonstrated typical for graphene\ndevices, which changes to unipolar characteristic if the surface graphene was\netched in oxygen plasma. Because amorphous carbon films can be growth easily,\nwith unlimited dimensions and no transfer of graphene is necessary, this can\nopen new perspective for graphene electronics."
    },
    {
        "anchor": "Valley-Dependent Magnetoresistance in Two-Dimensional Semiconductors: We show theoretically that two-dimensional direct-gap semiconductors with a\nvalley degree of freedom, including monolayer transition-metal dichalcogenides\nand gapped bilayer graphene, have a longitudinal magnetoconductivity\ncontribution that is odd in valley and odd in the magnetic field applied\nperpendicular to the system. Using a quantum kinetic theory we show how this\nvalley-dependent magnetoconductivity arises from the interplay between the\nmomentum-space Berry curvature of Bloch electrons, the presence of a magnetic\nfield, and disorder scattering. We discuss how the effect can be measured\nexperimentally and used as a detector of valley polarization.",
        "positive": "Charge response of the Majorana toric code: At zero temperature, a two dimensional lattice of Majorana zero modes on\nmesoscopic superconducting islands has a topologically ordered toric code\nphase. Recently, a Landau field theory has been proposed for the system that\ncaptures its different phases and the associated phase-transitions. It was\nshown that with the increase of Josephson tunneling between the islands, a\ncontinuous symmetry-breaking 3D-XY transition gets transformed into a discrete\nsymmetry-breaking 3D-Ising transition through a couple of tricritical points\nand first order transitions. Using the proposed field theory, we analyze the\ncharge-response of the system at the different continuous phase-transitions. We\ncalculate the universal conductivity at the 3D-XY transitions and the change in\nthe superconducting density at the Ising transition using 1/N expansion.\nFurthermore, by computing a one-loop correction to the field theory, we show\nthat an additional tricritical point is likely to be present in the\nphase-diagram. Finally, we provide a mean-field calculation that supports the\nearlier proposed field theory."
    },
    {
        "anchor": "Transport of Dirac quasiparticles in graphene: Hall and optical\n  conductivities: The analytical expressions for both diagonal and off-diagonal ac and dc\nconductivities of graphene placed in an external magnetic field are derived.\nThese conductivities exhibit rather unusual behavior as functions of frequency,\nchemical potential and applied field which is caused by the fact that the\nquasiparticle excitations in graphene are Dirac-like. One of the most striking\neffects observed in graphene is the odd integer quantum Hall effect. We argue\nthat it is caused by the anomalous properties of the Dirac quasiparticles from\nthe lowest Landau level. Other quantities such as Hall angle and Nernst signal\nalso exhibit rather unusual behavior, in particular when there is an excitonic\ngap in the spectrum of the Dirac quasiparticle excitations.",
        "positive": "Determination of the time scale of photoemission from the measurement of\n  spin polarization: The Eisenbud-Wigner-Smith (EWS) time delay of photoemission depends on the\nphase term of the matrix element describing the transition. Because of an\ninterference process between partial channels, the photoelectrons acquire a\nspin polarization which is also related to the phase term. The analytical model\nfor estimating the time delay by measuring the spin polarization is reviewed in\nthis manuscript. In particular, the distinction between scattering EWS and\ninterfering EWS time delay will be introduced, providing an insight in the\nchronoscopy of photoemission. The method is applied to the recent experimental\ndata for Cu(111) presented in M. Fanciulli et al., PRL 118, 067402 (2017),\nallowing to give better upper and lower bounds and estimates for the EWS time\ndelays."
    },
    {
        "anchor": "Electron subband degeneracy heat pump for cryogenic cooling: An unconventional method of continuous solid-state cryogenic cooling\nutilizing the electron subband degeneracy of semiconductor heterostructures is\nproposed in this Letter. An electrostatic heat pump is modeled, which employs\nsubband \"expansion\" and \"compression\" to reach sub-dilution refrigeration\ntemperatures with the fundamental limit set by electron-phonon interaction.\nUsing an ultra-wide GaAs quantum well as an example, the cooling power per unit\nvolume is estimated to reach $4.5\\ \\rm mW/cm^3$ with a hot-side temperature of\n$300\\ \\rm mK$, suitable for applications such as quantum computers or infrared\ndetectors.",
        "positive": "Statistics of heat transport across capacitively coupled double quantum\n  dot circuit: We study heat current and the full statistics of heat fluctuations in a\ncapacitively-coupled double quantum dot system. This work is motivated by\nrecent theoretical studies and experimental works on heat currents in quantum\ndot circuits. As expected intuitively, within the (static) mean-field\napproximation, the system at steady-state decouples into two single-dot\nequilibrium systems with renormalized dot energies, leading to zero average\nheat flux and fluctuations. This reveals that dynamic correlations induced\nbetween electrons on the dots is solely responsible for the heat transport\nbetween the two reservoirs. To study heat current fluctuations, we compute\nsteady-state cumulant generating function for heat exchanged between reservoirs\nusing two approaches : Lindblad quantum master equation approach, which is\nvalid for arbitrary coulomb interaction strength but weak system-reservoir\ncoupling strength, and the saddle point approximation for Schwinger-Keldysh\ncoherent state path integral, which is valid for arbitrary system-reservoir\ncoupling strength but weak coulomb interaction strength. Using thus obtained\ngenerating functions, we verify steady-state fluctuation theorem for stochastic\nheat flux and study the average heat current and its fluctuations. We find that\nthe heat current and its fluctuations change non-monotonically with the coulomb\ninteraction strength ($U$) and system-reservoir coupling strength ($\\Gamma$)\nand are suppressed for large values of $U$ and $\\Gamma$."
    },
    {
        "anchor": "Strain superlattices and macroscale suspension of Graphene induced by\n  corrugated substrates: We investigate the organized formation of strain, ripples and suspended\nfeatures in macroscopic CVD-prepared graphene sheets transferred onto a\ncorrugated substrate made of an ordered arrays of silica pillars of variable\ngeometries. Depending on the aspect ratio and sharpness of the corrugated\narray, graphene can conformally coat the surface, partially collapse, or lay,\nfakir-like, fully suspended between pillars over tens of micrometers. Upon\nincrease of pillar density, ripples in collapsed films display a transition\nfrom random oriented pleats emerging from pillars to ripples linking nearest\nneighboring pillars organized in domains of given orientation.\nSpatially-resolved Raman spectroscopy, atomic force microscopy and electronic\nmicroscopy reveal uniaxial strain domains in the transferred graphene, which\nare induced and controlled by the geometry. We propose a simple theoretical\nmodel to explain the transition between suspended and collapsed graphene. For\nthe arrays with high aspect ratio pillars, graphene membranes stays suspended\nover macroscopic distances with minimal interaction with pillars tip apex. It\noffers a platform to tailor stress in graphene layers and open perspectives for\nelectron transport and nanomechanical applications.",
        "positive": "Spin-relaxation and magnetoresistance in FM/SC/FM tunnel junctions: The effect of spin relaxation on tunnel magnetoresistance (TMR) in a\nferromagnet/superconductor/ferromagnet (FM/SC/FM) double tunnel junction is\ntheoretically studied. The spin accumulation in SC is determined by balancing\nof the spin-injection rate and the spin-relaxation rate. In the superconducting\nstate, the spin-relaxation time becomes longer with decreasing temperature,\nresulting in a rapid increase of TMR. The TMR of FM/SC/FM junctions provides a\nuseful probe to extract information about spin-relaxation in superconductors."
    },
    {
        "anchor": "Exchange in a silicon-based quantum dot quantum computer architecture: In bulk silicon, intervalley electronic interference has been shown to lead\nto strong oscillations in the exchange coupling between impurity electronic\nwavefunctions, posing a serious manufacturability problem for proposed quantum\ncomputers. Here we show that this problem does not arise in proposed\narchitectures using Si/SiGe quantum dots because of the large in-plane strain\nin Si quantum wells together with the strong confinement potential typical of\nheterostructures.",
        "positive": "Driven nonlinear nanomechanical resonators as digital signal detectors: Because of their nonlinearity, vibrational modes of resonantly driven\nnanomechanical systems have coexisting stable states of forced vibrations in a\ncertain range of the amplitude of the driving force. Depending on its phase,\nwhich encodes binary information, a signal at the same frequency increases or\ndecreases the force amplitude. The resulting force amplitude can be outside the\nrange of bistability. The values of the mode amplitude differ significantly on\nthe opposite sides of the bistability region. Therefore the mode amplitude is\nvery sensitive to the signal phase. This suggests using a driven mode as a\nbi-directional bifurcation amplifier, which switches in the opposite directions\ndepending on the signal phase and provides an essentially digital output. We\nstudy the operation of the amplifier near the critical point where the width of\nthe bistability region goes to zero and thus the threshold of the signal\namplitude is low. We also develop an analytical technique and study the error\nrate near the threshold. The results apply to a broad range of currently\nstudied systems and extend to micromechanical systems and nonlinear\nelectromagnetic cavities."
    },
    {
        "anchor": "Berry curvature inside parity-time-symmetry protected exceptional\n  surface: A three-dimensional non-Hermitian Hamiltonian with parity-time symmetry can\nexhibit a closed exceptional surface (EP surface) in momentum space, which is a\nnon-Hermitian deformation of the degeneracy line (DL). Since the degeneracy\nline lacks an internal space, the distributions of Berry curvature inside the\nEP surface becomes particularly intriguing. This paper studies the\ndistributions taking a torus-like EP surface as an example. In a meridian\ncross-section, the Berry connection exhibits a vortex-like field with only\nangular components, while the Berry curvature is perpendicular to this\ncross-section; in a equatorial cross-section, the Berry curvature forms a\nclosed curve surrounding the central genus. Both Berry connection and curvature\nconverge along the coplanar axis and diverge at the surface. We find the Berry\nflux depends on the radius of the integration region and is not quantized\ninside the EP torus. Approaching the surface, the Berry flux tends to infinity\nand the dynamical phase oscillates violently. We point that the streamlines of\nBerry curvature can be used to estimate the zero or non-zero Berry flux. We\ngeneralize the above patterns to the case of EP surfaces with complex shapes,\nand present a proposal of realizing the EP surface in an electrical circuit.\nOur research outcomes enhance the comprehension of EP surfaces and the\ntopological characteristics of non-Hermitian systems with parity-time (PT )\nsymmetry.",
        "positive": "Gradient expansion formalism for generic spin torques: We propose a new quantum-mechanical formalism to calculate spin torques based\non the gradient expansion, which naturally involves spacetime gradients of the\nmagnetization and electromagnetic fields. We have no assumption in the\nsmall-amplitude formalism or no difficulty in the SU($2$) gauge transformation\nformalism. As a representative, we calculate the spin renormalization, Gilbert\ndamping, spin-transfer torque, and $\\beta$-term in a three-dimensional\nferromagnetic metal with nonmagnetic and magnetic impurities being taken into\naccount within the self-consistent Born approximation. Our results serve as a\nfirst-principles formalism for spin torques."
    },
    {
        "anchor": "Charge Pumping and Photovoltaic effect in Open Quantum Dots: We propose a random matrix theory to describe the influence of a\ntime-dependent external field on electron transport through open quantum dots.\nWe describe the generation of the current by an oscillating field for the dot,\nconnected to two leads with equal chemical potentials. For low frequency fields\nour results correspond to adiabatic charge pumping. Finite current can be\nproduced if the system goes along a closed loop in parameter space, which\ncovers a finite area. At high frequency finite current is produced even if the\nloop is a line in parameter space. This result can be explained in the same way\nas adiabatic pumping but considering the evolution of the system in phase space\nrather than in parametric space.",
        "positive": "Interface-induced magnetism in perovskite quantum wells: We investigate the angular dependence of the magnetoresistance of thin (< 1\nnm), metallic SrTiO3 quantum wells epitaxially embedded in insulating,\nferrimagnetic GdTiO3 and insulating, antiferromagnetic SmTiO3, respectively.\nThe SrTiO3 quantum wells contain a high density of mobile electrons (~7x10^14\ncm^-2). We show that the longitudinal and transverse magnetoresistance in the\nstructures with GdTiO3 are consistent with anisotropic magnetoresistance, and\nthus indicative of induced ferromagnetism in the SrTiO3, rather than a\nnonequilibrium proximity effect. Comparison with the structures with\nantiferromagnetic SmTiO3 shows that the properties of thin SrTiO3 quantum wells\ncan be tuned to obtain magnetic states that do not exist in the bulk material."
    },
    {
        "anchor": "Optimum Size of Nanorods for Heating Application: Magnetic nanoparticles (MNP's) have become increasingly important in heating\napplications such as hyperthermia treatment of cancer due to their ability to\nrelease heat when a remote external alternating magnetic field is applied. It\nhas been shown that the heating capability of such particles varies\nsignificantly with the size of particles used. In this paper, we theoretically\nevaluate the heating capability of rod-shaped MNP's and identify conditions\nunder which these particles display highest efficiency. For optimally sized\nmonodisperse particles, the power generated by rod-shaped particles is found to\nbe equal to that generated by spherical particles. However, for particles which\nhave a dispersion in size, rod-shaped particles are found to be more effective\nin heating as a result of the greater spread in the power density distribution\ncurve. Additionally, for rod-shaped particles, a dispersion in the radius of\nthe particle contributes more to the reduction in loss power when compared to a\ndispersion in the length. We further identify the optimum size, i.e the radius\nand length of nanorods, given a bi-variate log-normal distribution of particle\nsize in two dimensions.",
        "positive": "Graphene Gas Osmometers: Here it is shown that graphene membranes that separate 2 gases at identical\npressure are deflected by osmotic pressure. The osmotic pressure is a\nconsequence of differences in gas permeation rates into a graphene enclosed\ncavity. The deflection of the few layer graphene membranes is detected by an\ninterferometric technique for measuring their tension-induced resonance\nfrequency. Using a calibration measurement of the relation between resonance\nfrequency and pressure, the time dependent osmotic pressure on the graphene is\nextracted. The osmotic pressure for different combinations of gases shows large\ndifferences that can be accounted for by a model based on the different gas\npermeation rates. Thus a graphene membrane based gas osmometer with a\nresponsitivity of ~60 kHz/mbar and nanoscale dimensions is demonstrated."
    },
    {
        "anchor": "Thermal conductivity of graphene isotope superlattices: Graphene has a high intrinsic thermal conductivity and a high electron\nmobility. The thermal conductivity of graphene can be significantly reduced\nwhen different carbon isotopes are mixed, which can enhance the performance of\nthermoelectric devices. Here we compare the thermal conductivities of isotopic\nc12/c13 random mixes with isotope superlattices with periods ranging from 46 to\n225 nm. Raman Opto-Thermal conductivity measurements of these superlattice\nstructures show an approximately 50% reduction in thermal conductivity compared\nto pristine c12 graphene. This average reduction is similar to the random\nisotope mix. The reduction of the thermal conductivity in the superlattice is\nwell described by a model of pristine graphene and an additional quasi-one\ndimensional periodic interfacial thermal resistance of (2.5\\pm 0.5)\\times\n10^{-11} m^2 K/W for the c12/c13 boundary. This is consistent with a large\nanisotropic thermal conductivity in the superlattice, where the thermal\nconductivity depends on the orientation of the c12/c13 boundary.",
        "positive": "Penetration Depth of Transverse Spin Current in Ferromagnetic Metals: The line width of the ferromagnetic resonance (FMR) spectrum of\nCu/CoFeB/Cu/Co/Cu is studied. Analyzing the FMR spectrum by the theory of spin\npumping, we determined the penetration depth of the transverse spin current in\nthe Co layer. The obtained penetration depth of Co is 1.7 nm."
    },
    {
        "anchor": "Direct electronic measurement of Peltier cooling and heating in graphene: Thermoelectric effects allow the generation of electrical power from waste\nheat and the electrical control of cooling and heating. Remarkably, these\neffects are also highly sensitive to the asymmetry in the density of states\naround the Fermi energy and can therefore be exploited as probes of distortions\nin the electronic structure at the nanoscale. Here we consider two-dimensional\ngraphene as an excellent nanoscale carbon material for exploring the\ninteraction between electronic and thermal transport phenomena, by presenting a\ndirect and quantitative measurement of the Peltier component to electronic\ncooling and heating in graphene. Thanks to an architecture including nanoscale\nthermometers, we detected Peltier component modulation of up to 15 mK for\ncurrents of 20 $\\mu$A at room temperature and observed a full reversal between\nPeltier cooling and heating for electron and hole regimes. This fundamental\nthermodynamic property is a complementary tool for the study of nanoscale\nthermoelectric transport in two-dimensional materials.",
        "positive": "Quadratic and Cubic Nodal Lines Stabilized by Crystalline Symmetry: In electronic band structures, nodal lines may arise when two (or more) bands\ncontact and form a one-dimensional manifold of degeneracy in the Brillouin\nzone. Around a nodal line, the dispersion for the energy difference between the\nbands is typically linear in any plane transverse to the line. Here, we perform\nan exhaustive search over all 230 space groups for nodal lines with\nhigher-order dispersions that can be stabilized by crystalline symmetry in\nsolid state systems with spin-orbit coupling and time reversal symmetry. We\nfind that besides conventional linear nodal lines, only lines with quadratic or\ncubic dispersions are possible, for which the allowed degeneracy cannot be\nlarger than two. We derive effective Hamiltonians to characterize the novel\nlow-energy fermionic excitations for the quadratic and cubic nodal lines, and\nexplicitly construct minimal lattice models to further demonstrate their\nexistence. Their signatures can manifest in a variety of physical properties\nsuch as the (joint) density of states, magneto-response, transport behavior,\nand topological surface states. Using ab-initio calculations, we also identify\npossible material candidates that realize these exotic nodal lines."
    },
    {
        "anchor": "Quantum Oscillations from Surface Fermi-Arcs in Weyl and Dirac\n  Semi-Metals: The surface states of Weyl semi-metals (SM's) consist of disjointed\nFermi-arcs. This unusual surface-Fermiology provides a fingerprint of the\ntopological features of the bulk Weyl-phase. Using a combination of\nsemiclassical and numerical methods, we show that, in contrast to naive\nexpectation, there are closed magnetic orbits involving the open- surface\nFermi-arcs. Below a critical field strength that depends on sample thickness,\nthese orbits produce periodic quantum oscillations of the density of states in\na magnetic field, enabling a variety of experimental probes of the\nunconventional Fermi-arc surface states. The orbits are also essential for\nreproducing the bulk chiral anomaly in a finite slab. These results are then\nextended to the closely related and recently discovered 3D Dirac SM materials,\nincluding Cd3As2 and Na3Bi, which are doubled copies of Weyl semi-metals\nprotected by crystal symmetry. Despite the fact that the protecting crystal\nsymmetry is broken by a surface, we show that Dirac materials can still host\nunconventional surface-states, which can be detected in quantum oscillations\nexperiments.",
        "positive": "Electrical Contact between an Ultrathin Topological Dirac Semimetal and\n  a Two-Dimensional Material: Ultrathin films of topological Dirac semimetal, Na$_3$Bi, has recently been\nrevealed as an unusual electronic materials with field-tunable topological\nphases. Here we investigate the electronic and transport properties of\nultrathin Na$_3$Bi as an electrical contact to two-dimensional (2D) metal, i.e.\ngraphene, and 2D semiconductor, i.e. MoS$_2$ and WS$_2$ monolayers. Using\ncombined first-principle density functional theory and nonequilibrium Green's\nfunction simulation, we show that the electrical coupling between Na$_3$Bi\nbilayer thin film and graphene results in a notable interlayer charge transfer,\nthus inducing sizable $n$-type doping in the Na$_3$Bi/graphene\nheterostructures. In the case of MoS$_2$ and WS$_2$ monolayers, the lateral\nSchottky transport barrier is significantly lower than many commonly studied\nbulk metals, thus unraveling Na$_3$Bi bilayer as a high-efficiency electrical\ncontact material for 2D semiconductors. These findings opens up an avenue of\nutilizing topological semimetal thin film as electrical contact to 2D\nmaterials, and further expands the family of 2D heterostructure devices into\nthe realm of topological materials."
    },
    {
        "anchor": "Experimental evidences of a large extrinsic spin Hall effect in AuW\n  alloy: We report an experimental study of a gold-tungsten alloy (7% at. W\nconcentration in Au host) displaying remarkable properties for spintronics\napplications using both magneto-transport in lateral spin valve devices and\nspin-pumping with inverse spin Hall effect experiments. A very large spin Hall\nangle of about 10% is consistently found using both techniques with the\nreliable spin diffusion length of 2 nm estimated by the spin sink experiments\nin the lateral spin valves. With its chemical stability, high resistivity and\nsmall induced damping, this AuW alloy may find applications in the nearest\nfuture.",
        "positive": "Transport Signatures of Majorana Quantum Criticality Realized by\n  Dissipative Resonant Tunneling: We consider theoretically the transport properties of a spinless resonant\nelectronic level coupled to strongly dissipative leads, in the regime of\ncircuit impedance near the resistance quantum. Using the Luttinger liquid\nanalogy, one obtains an effective Hamiltonian expressed in terms of interacting\nMajorana fermions, in which all environmental degrees of freedom (leads and\nelectromagnetic modes) are encapsulated in a single fermionic bath. General\ntransport equations for this system are then derived in terms of the Majorana\nT-matrix. Perturbative treatment of the Majorana interaction term yields the\nappearance of a marginal, linear dependence of the conductance on temperature\nwhen the system is tuned to its quantum critical point, in agreement with\nrecent experimental observations. We investigate in detail the different\ncrossovers involved in the problem, and analyze the role of the interaction\nterms in the transport scaling functions. In particular, we show that single\nbarrier scaling applies when the system is slightly tuned away from its\nMajorana critical point, strengthening the general picture of dynamical Coulomb\nblockade."
    },
    {
        "anchor": "Correlated electron current and temperature dependence of the\n  conductance of a quantum point contact: We investigate finite temperature corrections to the Landauer formula due to\nelectron-electron interaction within the quantum point contact. When the Fermi\nlevel is close to the barrier height, the interaction is strongly enhanced due\nto semiclassical slowing of the electrons. To describe electron transport we\nformulate and solve a nonlocal kinetic equation for the density matrix of\nelectrons. The correction to the conductance $G$ is negative and strongly\nenhanced in the region 0.5*2e^2/h < G < 1*2e^2/h . Our results for conductance\nagree with the so-called ``0.7 structure'' observed in experiments..",
        "positive": "Edge and surface plasmons in graphene nanoribbons: We report on nano-infrared (IR) imaging studies of confined plasmon modes\ninside patterned graphene nanoribbons (GNRs) fabricated with high-quality\nchemical-vapor-deposited (CVD) graphene on Al2O3 substrates. The confined\ngeometry of these ribbons leads to distinct mode patterns and strong field\nenhancement, both of which evolve systematically with the ribbon width. In\naddition, spectroscopic nano-imaging in mid-infrared 850-1450 cm-1 allowed us\nto evaluate the effect of the substrate phonons on the plasmon damping.\nFurthermore, we observed edge plasmons: peculiar one-dimensional modes\npropagating strictly along the edges of our patterned graphene nanostructures."
    },
    {
        "anchor": "Capacitance and charging of metallic objects: The capacitance of arbitrarily shaped objects is reformulated in terms of the\nNeumann-Poincar\\'{e} operator. Capacitance is simply the dielectric\npermittivity of the surrounding medium multiplied by the area of the object and\ndivided by the squared norm of the Neumann-Poincar\\'{e} eigenfunction that\ncorresponds to its largest eigenvalue. The norm of this eigenfunction varies\nslowly with shape changes and allows perturbative calculations. This result is\nalso extended to capacitors. For axisymmetric geometries a numerical method\nprovides excellent results against finite element method results. Two\nscale-invariant shape factors and the capacitance of nanowires and of membrane\nin biological cells are discussed.",
        "positive": "Anisotropic Stark Effect and Electric-Field Noise Suppression for\n  Phosphorus Donor Qubits in Silicon: We report the use of novel, capacitively terminated coplanar waveguide (CPW)\nresonators to measure the quadratic Stark shift of phosphorus donor qubits in\nSi. We confirm that valley repopulation leads to an anisotropic spin-orbit\nStark shift depending on electric and magnetic field orientations relative to\nthe Si crystal. By measuring the linear Stark effect, we estimate the effective\nelectric field due to strain in our samples. We show that in the presence of\nthis strain, electric-field sources of decoherence can be non-negligible. Using\nour measured values for the Stark shift, we predict magnetic fields for which\nthe spin-orbit Stark effect cancels the hyperfine Stark effect, suppressing\ndecoherence from electric-field noise. We discuss the limitations of these\nnoise-suppression points due to random distributions of strain and propose a\nmethod for overcoming them."
    },
    {
        "anchor": "Non-Adiabatic Effect in Topological and Interacting Charge Pumping: Topological charge pumping occurs in the adiabatic limit, and the\nnon-adiabatic effect due to finite ramping velocity reduces the pumping\nefficiency and leads to deviation from quantized charge pumping. In this work,\nwe discuss the relation between this deviation from quantized charge pumping\nand the entanglement generation after a pumping circle. In the simplest\nsetting, we show that purity $\\mathcal{P}$ of the half system reduced density\nmatrix equals to $\\mathcal{R}$ defined as $(1-\\kappa)^2+\\kappa^2$, where\n$\\kappa$ denotes the pumping efficiency. In generic situations, we argue\n$\\mathcal{P}<\\mathcal{R}$ and the pumping efficiency can provide an upper bound\nfor purity and, therefore, a lower bound for generated entanglement. To support\nthis conjecture, we propose a solvable pumping scheme in the\nRice--Mele--Hubbard model, which can be represented as brick-wall type quantum\ncircuit model. With this pumping scheme, numerical calculation of charge\npumping only needs to include at most six sites, and therefore, the interaction\nand the finite temperature effects can be both included reliably in the exact\ndiagonalization calculation. The numerical results using the solvable pumping\ncircle identify two regimes where the pumping efficiency is sensitive to\nramping velocity and support the conjecture $\\mathcal{P}<\\mathcal{R}$ when both\ninteraction and finite temperature effects are present.",
        "positive": "High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter: We demonstrate high efficiency Cooper pair splitting in a graphene-based\ndevice. We utilize a true Y-shape design effectively placing the splitting\nchannels closer together: graphene is used as the central superconducting\nelectrode as well as QD output channels, unlike previous designs where a\nconventional superconductor was used with tunnel barriers to the quantum dots\n(QD) of a different material. Superconductivity in graphene is induced via the\nproximity effect, thus resulting in both a large measured superconducting gap\n$\\Delta=0.5$meV, and a long coherence length $\\xi=200$nm. The\ngraphene-graphene, flat, two dimensional, superconductor-QD interface lowers\nthe capacitance of the quantum dots, thus increasing the charging energy $E_C$\n(in contrast to previous devices). As a result we measure a visibility of up to\n96% and a splitting efficiency of up to 62%. Finally, the devices utilize\ngraphene grown by chemical vapor deposition allowing for a standardized device\ndesign with potential for increased complexity."
    },
    {
        "anchor": "Mobility enhancement in graphene by in situ reduction of random strain\n  fluctuations: Microscopic corrugations are ubiquitous in graphene even when placed on\natomically flat substrates. These result in random local strain fluctuations\nlimiting the carrier mobility of high quality hBN-supported graphene devices.\nWe present transport measurements in hBN-encapsulated devices where such strain\nfluctuations can be in situ reduced by increasing the average uniaxial strain.\nWhen $\\sim0.2\\%$ of uniaxial strain is applied to the graphene, an enhancement\nof the carrier mobility by $\\sim35\\%$ is observed while the residual doping\nreduces by $\\sim39\\%$. We demonstrate a strong correlation between the mobility\nand the residual doping, from which we conclude that random local strain\nfluctuations are the dominant source of disorder limiting the mobility in these\ndevices. Our findings are also supported by Raman spectroscopy measurements.",
        "positive": "Magnetic field induced luminescence spectra in a quantum cascade laser: We report on our study of the luminescence spectra of a quantum cascade laser\nin the presence of an external magnetic field tilted from the direction\nperpendicular to the electron plane. The effect of the tilted field is to allow\nnovel optical transitions because of the coupling of intersubband-cyclotron\nenergies. We find that by tuning the applied field, one can get optical\ntransitions at different energies that are as sharp as the zero-field\ntransitions."
    },
    {
        "anchor": "Persistent Current States in Bilayer Graphene: We argue that at finite carrier density and large displacement fields,\nbilayer graphene is prone to $\\ell =0$ and $\\ell = 1$ Pomeranchuk Fermi surface\ninstabilities. The broken symmetries are driven by non-local exchange\ninteractions which favor momentum space condensation. We find that\nelectron-electron interactions lead first to spontaneous valley polarization,\nwhich breaks time-reversal invariance and is associated with spontaneous\norbital magnetism, and then under some circumstances to a nematic phase with\nreduced rotational symmetry. When present, nematic order is signaled by reduced\nsymmetry in the dependence of optical absorption on light polarization.",
        "positive": "Current-induced breakdown of the quantum anomalous Hall effect: The quantum anomalous Hall effect (QAHE) realizes dissipationless\nlongitudinal resistivity and quantized Hall resistance without the need of an\nexternal magnetic field. However, when reducing the device dimensions or\nincreasing the current density, an abrupt breakdown of the dissipationless\nstate occurs with a relatively small critical current, limiting the\napplications of the QAHE. We investigate the mechanism of this breakdown by\nstudying multi-terminal devices and identified that the electric field created\nbetween opposing chiral edge states lies at the origin. We propose that\nelectric-field-driven percolation of two-dimensional charge puddles in the\ngapped surface states of compensated topological-insulator films is the most\nlikely cause of the breakdown."
    },
    {
        "anchor": "Measuring the Momentum of a Nanomechanical Oscillator through the Use of\n  Two Tunnel Junctions: We propose a way to measure the momentum p of a nanomechanical oscillator.\nThe p-detector is based on two tunnel junctions in a Aharonov-Bohm-type setup.\nOne of the tunneling amplitudes depends on the motion of the oscillator, the\nother one not. Although the coupling between the detector and the oscillator is\nassumed to be linear in the position x of the oscillator, it turns out that the\nfinite-frequency noise output of the detector will in general contain a term\nproportional to the momentum spectrum of the oscillator. This is a true quantum\nphenomenon, which can be realized in practice if the phase of the tunneling\namplitude of the detector is tuned by the Aharonov-Bohm flux Phi to a\np-sensitive value.",
        "positive": "Fano Effect through Parallel-coupled Double Coulomb Islands: By means of the non-equilibrium Green function and equation of motion method,\nthe electronic transport is theoretically studied through a parallel-coupled\ndouble quantum dots(DQD) in the presence of the on-dot Coulomb correlation,\nwith an emphasis put on the quantum interference. It has been found that in the\nCoulomb blockage regime, the quantum interference between the bonding and\nantiboding DQD states or that between their Coulomb blockade counterparts may\nresult in the Fano resonance in the conductance spectra, and the Fano peak\ndoublet may be observed under certain non-equilibrium condition. The\npossibility of manipulating the Fano lineshape is predicted by tuning the\ndot-lead coupling and magnetic flux threading the ring connecting the dots and\nleads. Similar to the case without Coulomb interaction, the direction of the\nasymmetric tail of Fano lineshape can be flipped by the external field. Most\nimportantly, by tuning the magnetic flux, the function of four relevant states\ncan be interchanged, giving rise to the swap effect, which might play a key\nrole as a qubit in the quantum computation."
    },
    {
        "anchor": "A tunable Fabry-P\u00e9rot quantum Hall interferometer in graphene: Electron interferometry with quantum Hall edge channels holds promise for\nprobing and harnessing exotic exchange statistics of non-Abelian anyons. In\nsemiconductor heterostructures, however, quantum Hall interferometry has proven\nchallenging and often obscured by charging effects. Here we show that\nhigh-mobility monolayer graphene equipped with a series of gate-tunable quantum\npoint contacts that act as electron beam-splitters provides a model system to\nperform Fabry-P\\'{e}rot quantum Hall interferometry. We observe high-visibility\nAharonov-Bohm interference free of charging effects and widely tunable through\nelectrostatic gating or magnetic field, in remarkable agreement with theory. A\ncoherence length of $\\mathbf{10 \\,\\mu m}$ at a temperature of $0.02$ K allows\nus to further achieve coherently-coupled double Fabry-P\\'{e}rot interferometry.\nOur results open a new avenue for quantum Hall interferometry and the\nexploitation of topological excitations for quantum computation.",
        "positive": "Shot noise detection in hBN-based tunnel junctions: High quality Au/hBN/Au tunnel devices are fabricated using transferred\natomically thin hexagonal boron nitride as the tunneling barrier. All tunnel\njunctions show tunneling resistance on the order of several\nk$\\Omega$/$\\mu$m$^{2}$. Ohmic I-V curves at small bias with no signs of\nresonances indicate the sparsity of defects. Tunneling current shot noise is\nmeasured in these devices, and the excess shot noise shows consistency with\ntheoretical expectations. These results show that atomically thin hBN is an\nexcellent tunnel barrier, especially for the study of shot noise properties,\nand this can enable the study of tunneling density of states and shot noise\nspectroscopy in more complex systems."
    },
    {
        "anchor": "Transport measurement of fractional charges in topological models: The static topological fractional charge (TFC) in condensed matter systems is\nrelated to the band topology and thus has potential applications in topological\nquantum computation. However, the experimental measurement of these TFCs in\nelectronic systems is quite challenging. We propose an electronic transport\nmeasurement scheme that both the charge amount and the spatial distribution of\nthe TFC can be extracted from the differential conductance through a quantum\ndot coupled to the topological system being measured. For one-dimensional\nSu-Schrieffer-Heeger (SSH) model, both the $e/2$ charge of the TFC and its\ndistribution can be verified. We also show that the Anderson disorder effect,\nwhich breaks certain symmetry related to the TFC, is significant in\nhigher-dimensional systems while has little effect on the one-dimensional SSH\nchain. Nonetheless, our measurement scheme can still work well for specific\nhigher-order topological insulator materials, for instance, the $2e/3$ TFC in\nthe breathing kagome model could be confirmed even in the presence of disorder\neffect.",
        "positive": "Gatemon Benchmarking and Two-Qubit Operation: Recent experiments have demonstrated superconducting transmon qubits with\nsemiconductor nanowire Josephson junctions. These hybrid gatemon qubits utilize\nfield effect tunability characteristic for semiconductors to allow complete\nqubit control using gate voltages, potentially a technological advantage over\nconventional flux-controlled transmons. Here, we present experiments with a\ntwo-qubit gatemon circuit. We characterize qubit coherence and stability and\nuse randomized benchmarking to demonstrate single-qubit gate errors below 0.7%\nfor all gates, including voltage-controlled $Z$ rotations. We show coherent\ncapacitive coupling between two gatemons and coherent swap operations. Finally,\nwe perform a two-qubit controlled-phase gate with an estimated fidelity of 91%,\ndemonstrating the potential of gatemon qubits for building scalable quantum\nprocessors."
    },
    {
        "anchor": "Low-dimensional polaritonics: Emergent non-trivial topology on\n  exciton-polariton simulators: Polaritonic lattice configurations in dimensions $D=2$ are used as simulators\nof topological phases, based on symmetry class A Hamiltonians. Numerical and\ntopological studies are performed in order to characterise the bulk topology of\ninsulating phases, which is predicted to be connected to non-trivial edge mode\nstates on the boundary. By using spectral flattened Hamiltonians on specific\nlattice geometries with time reversal symmetry breaking, e.g. Kagome lattice,\nwe obtain maps from the Brillouin zone into Grassmannian spaces, which are\nfurther investigated by the topological method of space fibrations. Numerical\nevidence reveals a connection between the sum of valence band Chern numbers and\nthe index of the projection operator onto the valence band states. Along these\nlines, we discover an index formula which resembles other index theorems and\nthe classical result of Atiyah-Singer, but without any Dirac operator and from\na different perspective. Through a combination of different tools, in\nparticular homotopy and homology-cohomology duality, we provide a comprehensive\nmathematical framework, which fully addresses the source and structure of\ntopological phases in coupled polaritonic array systems. Based on these\nresults, it becomes possible to infer further designs and models of\ntwo-dimensional single sheet Chern insulators, implemented as polariton\nsimulators.",
        "positive": "Magnetization dynamics induced by in-plane currents in ultrathin\n  magnetic nanostructures: Ultrathin magnetic systems have properties qualitatively different from their\nthicker counterparts, implying that different physics governs their properties.\nWe demonstrate that various such properties can be explained naturally by the\nRashba spin-orbit coupling in ultrathin magnetic systems. This work will be\nvaluable for the development of next generation spintronic devices based on\nultrathin magnetic systems."
    },
    {
        "anchor": "Dynamical Floquet spectrum of Kekul\u00e9-distorted graphene under normal\n  incidence of electromagnetic radiation: Electromagnetic dressing by a high-frequency field drastically modifies the\nelectronic transport properties on Dirac systems. Here its effects on the\nenergy spectrum of graphene with two possible phases of Kekul\\'e distortion\n(namely, Kek-Y and Kek-O textures) are studied. Using Floquet theory it is\nshown how circularly polarized light modifies the gapless spectrum of the Kek-Y\ntexture, producing dynamical band gaps at the Dirac point that depends on the\namplitude and the frequency of the electric field, and breaks the valley\ndegeneracy of the gapped spectrum of the Kek-O texture. To further explore the\nelectronic properties under circularly polarized radiation, the dc conductivity\nis studied by using the Boltzmann approach and considering both inter-valley\nand intra-valley contributions. When linearly polarized light is considered,\nthe band structure of both textures is always modified in a perpendicular\ndirection to the electric field. While the band structure for the Kek-Y texture\nremains gapless, the gap for the Kek-O texture is reduced considerably. For\nthis linear polarization it is also shown that non-dispersive bands can appear\nby a precise tuning of the light field parameters thus inducing dynamical\nlocalization. The present results suggest that optical measurements will allow\nto distinguish between different Kekul\\'e bond textures.",
        "positive": "A Micromagnetic Study of Magnetization Reversal in Ferromagnetic\n  Nanorings: We present results of micromagnetic simulations of thin ferromagnetic rings\nundergoing magnetization reversal. This geometry is one of few examples in\nmicromagnetics in which the transition states have been found analytically in a\n1D model. According to this model, at low fields and large ring sizes, the\nenergetically preferred transition state is a localized magnetization\nfluctuation (instanton saddle). At high fields and small ring size, the\npreferred saddle state is a uniformly rotated magnetization (constant saddle).\nIn the first part of this paper, we use numerical micromagnetic simulations to\ntest these predictions of the 1D analytical model for more realistic\nsituations, including a variety of ring radii, annular widths and magnetic\nfields. The predicted activation energies for magnetization reversal are found\nto be in close agreement with numerical results, even for rings with a large\nannular width where the 1D approximation would be expected to break down. We\nfind that this approximation breaks down only when the ring's annular width\nexceeds its radius. In the second part, we present new metastable states found\nin the large radius limit and discuss how they provide a more complete\nunderstanding of the energy landscape of magnetic nanorings."
    },
    {
        "anchor": "Plasmon coupling in extended structures: Graphene superlattice\n  nanoribbon arrays: Interactions between localized plasmons in proximal nanostructures is a\nwell-studied phenomenon. Here we explore plasmon plasmon interactions in\nconnected extended systems. Such systems can now be easily produced using\ngraphene. Specifically we employ the finite element method to study such\ninteractions in graphene nanoribbon arrays with a periodically modulated\nelectrochemical potential or number of layers. We find a rich variation in the\nresulting plasmonic resonances depending on the dimensions and the\nelectrochemical potentials (doping) of the nanoribbon segments and the\ninvolvement of transverse and longitudinal plasmon interactions. Unlike\npredictions based of the well-known \"orbital hybridization model\", the energies\nof the resulting hybrid plasmonic resonances of the extended system can lie\nbetween the energies of the plasmons of the individual components. The results\ndemonstrate the wide range tunability of the graphene plasmons and can help to\ndesign structures with desired spectra, which can be used to enhance optical\nfields in the infrared region of the electromagnetic spectrum.",
        "positive": "Scanning gradiometry with a single spin quantum magnetometer: Here, we demonstrate a gradiometry technique that significantly enhances the\nmeasurement sensitivity of such static fields, leading to new opportunities in\nthe imaging of weakly magnetic systems. Our method relies on the mechanical\noscillation of a single nitrogen-vacancy center at the tip of a scanning\ndiamond probe, which up-converts the local spatial gradients into ac magnetic\nfields enabling the use of sensitive ac quantum protocols. We show that\ngradiometry provides important advantages over static field imaging: (i) an\norder-of-magnitude better sensitivity, (ii) a more localized and sharper image,\nand (iii) a strong suppression of field drifts. We demonstrate the capabilities\nof gradiometry by imaging the nanotesla fields appearing above topographic\ndefects and atomic steps in an antiferromagnet, direct currents in a graphene\ndevice, and para- and diamagnetic metals."
    },
    {
        "anchor": "Very large thermal rectification in ferromagnetic insulator-based\n  superconducting tunnel junctions: We investigate electronic thermal rectification in ferromagnetic\ninsulator-based superconducting tunnel junctions. Ferromagnetic insulators\ncoupled to superconductors are known to induce sizable spin splitting in the\nsuperconducting density of states, and also lead to efficient spin filtering if\noperated as tunnel barriers. The combination of spin splitting and spin\nfiltering is shown to yield a substantial self-amplification of the electronic\nheat diode effect due to breaking of the electron-hole symmetry in the system\nwhich is added to the thermal asymmetry of the junction. Large spin splitting\nand large spin polarization can potentially lead to thermal rectification\nefficiency exceeding 5 .10^4 for realistic parameters in a suitable temperature\nrange, thereby outperforming up to a factor of 250 the heat diode effect\nachievable with conventional superconducting tunnel junctions. These results\ncould be relevant for improved mastering of the heat currents in innovative\nphase-coherent caloritronic nanodevices, and for enhanced thermal management of\nquantum circuits at the nanoscale.",
        "positive": "Hysteretic behavior and evidence for domain formation in a double-layer\n  quantum Hall system at total filling factor 2: We report anomalous behavior in a double-layer two dimensional hole gas\n(2DHG) at even integer filling factors which includes hysteresis in the\nlongitudinal and Hall resistances and a very weak temperature dependence of the\nresistance minima. All anomalies disappear and the conventional quantum Hall\neffect behavior recovers when a thin metal film is placed on top of the 2DHG.\nThe behavior is attributed to presence of the theoretically predicted magnetic\nordering at even integer filling factors which causes the formation of\nmacroscopic spin-charge domains."
    },
    {
        "anchor": "Electromigrated nanoscale gaps for surface-enhanced Raman spectroscopy: Single-molecule detection with chemical specificity is a powerful and much\ndesired tool for biology, chemistry, physics, and sensing technologies.\nSurface-enhanced spectroscopies enable single molecule studies, yet reliable\nsubstrates of adequate sensitivity are in short supply. We present a simple,\nscaleable substrate for surface-enhanced Raman spectroscopy (SERS)\nincorporating nanometer-scale electromigrated gaps between extended electrodes.\nMolecules in the nanogap active regions exhibit hallmarks of very high Raman\nsensitivity, including blinking and spectral diffusion. Electrodynamic\nsimulations show plasmonic focusing, giving electromagnetic enhancements\napproaching those needed for single-molecule SERS.",
        "positive": "Chirality of nanophotonic waveguide with embedded quantum emitter for\n  unidirectional spin transfer: Scalable quantum technologies require faithful conversion between matter\nqubits storing the quantum information and photonic qubits carrying the\ninformation in integrated circuits and waveguides. We demonstrate that the\nelectromagnetic field chirality which arises in nanophotonic waveguides leads\nto unidirectional emission from an embedded quantum dot quantum emitter, with\nresultant in-plane transfer of matter-qubit (spin) information. The chiral\nbehavior occurs despite the non-chiral geometry and material of the waveguides.\nUsing dot registration techniques we achieve a quantum emitter\ndeterministically positioned at a chiral point and realize spin-path conversion\nby design. We measure and compare the phenomena in single mode nanobeam and\nphotonic crystal waveguides. The former is much more tolerant to dot position,\nexhibits experimental spin-path readout as high as 95 +/- 5% and has potential\nto serve as the basis of future spin-logic and network implementations."
    },
    {
        "anchor": "Non-equilibrium Band Broadening, Gap Renormalization and Band Inversion\n  in Black Phosphorus: Black phosphorous (BP) is a layered semiconductor with high carrier mobility,\nanisotropic optical response and wide bandgap tunability. In view of its\napplication in optoelectronic devices, understanding transient photo-induced\neffects is crucial. Here, we investigate by time- and angle-resolved\nphotoemission spectroscopy BP in its pristine state and in the presence of\nStark splitting, chemically induced by Cs ad-sorption. We show that\nphoto-injected carriers trigger bandgap renormalization and a concurrent\nvalence band attening caused by Pauli blocking. In the biased sample,\nphotoexcitation leads to a long-lived (ns) surface photovoltage of few hundreds\nmV that counterbalances the Cs-induced surface band bending. This allows us to\ndisentangle bulk from surface electronic states and to clarify the mechanism\nunderlying the band inversion observed in bulk samples.",
        "positive": "Twisted light-induced spin-spin interaction in a chiral helimagnet: We theoretically investigate how the orbital angular momentum of light can\naffect a chiral magnetic order. Here, we consider a metallic chiral helimagnet,\nwhich is under stationary radiation of a resonant optical vortex beam. We\npropose a novel interaction between local spins considering microscopic\ninteractions between an optical vortex and electrons. This vortex-induced\ninteraction modulates the chiral magnetic order in an entirely different way\nthan an external magnetic field does. Our spin modulation technique may pave a\nroute to create a unique topological or chiral structure for future\nopto-spintronics devices."
    },
    {
        "anchor": "Collapse of the Fano Resonance Caused by the Nonlocality of the Majorana\n  State: One of the main features of the Majorana state, which attracts a considerable\ncurrent interest to these excitations in solid-state systems, is related to its\nnonlocal character. It is demonstrated that the direct consequence of such\nnonlocality is the collapse of the Fano resonance manifesting itself in the\nconductance of an asymmetric interference device, the arms of which are\nconnected by a one-dimensional topological superconductor. In the framework of\nthe spinless model, it is shown that the predicted effect is associated with an\nincrease in the multiplicity of the degeneracy of the zero-energy state of the\nstructure arising at a specific case of the Kitaev model. Such an increase\nleads to the formation of a bound state in the continuum.",
        "positive": "Coherent control of macroscopic quantum states in a single-Cooper-pair\n  box: A small superconducting electrode (a single-Cooper-pair box) connected to a\nreservoir via a Josephson junction constitutes an artificial two-level system,\nin which two charge states that differ by 2e are coupled by tunneling of Cooper\npairs. Despite its macroscopic nature involving a large number of electrons,\nthe two-level system shows coherent superposition of the two charge states, and\nhas been suggested as a candidate for a qubit, i.e. a basic component of a\nquantum computer. Here we report on time-domain observation of the coherent\nquantum-state evolution in the two-level system by applying a short voltage\npulse that modifies the energies of the two levels nonadiabatically to control\nthe coherent evolution. The resulting state was probed by a tunneling current\nthrough an additional probe junction. Our results demonstrate coherent\noperation and measurement of a quantum state of a single two-level system, i.e.\na qubit, in a solid-state electronic device."
    },
    {
        "anchor": "Position controlled self-catalyzed growth of GaAs nanowires by molecular\n  beam epitaxy: GaAs nanowires are grown by molecular beam epitaxy using a self-catalyzed,\nGa-assisted growth technique. Position control is achieved by nano-patterning a\nSiO2 layer with arrays of holes with a hole diameter of 85 nm and a hole pitch\nvarying between 200 nm and 2 \\mum. Gallium droplets form preferentially at the\netched holes acting as catalyst for the nanowire growth. The nanowires have\nhexagonal cross-sections with {110} side facets and crystallize predominantly\nin zincblende. The interdistance dependence of the nanowire growth rate\nindicates a change of the III/V ratio towards As-rich conditions for large hole\ndistances inhibiting NW growth.",
        "positive": "Fine structure of excitons in InAs quantum dots on GaAs(110) planar\n  layers and nanowire facets: We investigate the optical properties of InAs quantum dots grown by molecular\nbeam epitaxy on GaAs(110) using Bi as a surfactant. The quantum dots are\nsynthesized on planar GaAs(110) substrates as well as on the {110} sidewall\nfacets of GaAs nanowires. At 10 K, neutral excitons confined in these quantum\ndots give rise to photoluminescence lines between 1.1 and 1.4 eV.\nMagneto-photoluminescence spectroscopy reveals that for small quantum dots\nemitting between 1.3 and 1.4 eV, the electron-hole coherence length in and\nperpendicular to the (110) plane is on the order of 5 and 2 nm, respectively.\nThe quantum dot photoluminescence is linearly polarized, and both binding and\nantibinding biexcitons are observed, two findings that we associate with the\nstrain in the (110) plane This strain leads to piezoelectric fields and to a\nstrong mixing between heavy and light hole states, and offers the possibility\nto tune the degree of linear polarization of the exciton photoluminescence as\nwell as the sign of the binding energy of biexcitons."
    },
    {
        "anchor": "Measurements of Kondo and spin splitting in single-electron transistors: We measure the spin splitting in a magnetic field $B$ of localized states in\nsingle-electron transistors using a new method, inelastic spin-flip\ncotunneling. Because it involves only internal excitations, this technique\ngives the most precise value of the Zeeman energy $\\Delta = \\ZeemanE$. In the\nsame devices we also measure the splitting with $B$ of the Kondo peak in\ndifferential conductance. The Kondo splitting appears only above a threshold\nfield as predicted by theory. However, the magnitude of the Kondo splitting at\nhigh fields exceeds $2 \\ZeemanE$ in disagreement with theory.",
        "positive": "Interlayer exciton dynamics in a dichalcogenide monolayer\n  heterostructure: In heterostructures consisting of different transition-metal dichalcogenide\nmonolayers, a staggered band alignment can occur, leading to rapid charge\nseparation of optically generated electron-hole pairs into opposite monolayers.\nThese spatially separated electron-hole pairs are Coulomb-coupled and form\ninterlayer excitons. Here, we study these interlayer excitons in a\nheterostructure consisting of MoSe$_2$ and WSe$_2$ monolayers using\nphotoluminescence spectroscopy. We observe a non-trivial temperature dependence\nof the linewidth and the peak energy of the interlayer exciton, including an\nunusually strong initial redshift of the transition with temperature, as well\nas a pronounced blueshift of the emission energy with increasing excitation\npower. By combining these observations with time-resolved photoluminescence\nmeasurements, we are able to explain the observed behavior as a combination of\ninterlayer exciton diffusion and dipolar, repulsive exciton-exciton\ninteraction."
    },
    {
        "anchor": "Global consequences of a local Casimir force: Adhered cantilever: Although stiction is a cumbersome problem for microsystems, it stimulates\ninvestigations of surface adhesion. In fact, the shape of an adhered cantilever\ncarries information of the adhesion energy that locks one end to the substrate.\nWe demonstrate here that the system is also sensitive to the dispersion forces\nthat are operative very close to the point of contact, but their contribution\nto the shape is maximum at about one third of the unadhered length. When the\nforce exceeds a critical value the cantilever does not lose stability but it\nsettles at smaller unadhered length, whose relation to adhesion energy is only\nslightly affected by the force. Our calculations suggest to use adhered\ncantilevers to measure the dispersion forces at short separations, where other\nmethods suffer from jump-to-contact instability. Simultaneous measurement of\nthe force and adhesion energy allows the separation of the dispersion\ncontribution to the surface adhesion.",
        "positive": "Strong suppression of near-field thermal transport between twisted\n  bilayer graphene near the magic angle: Twisted bilayer graphene (TBLG) has recently emerged as a versatile platform\nfor studying a variety of exotic transport phenomena. Here, we present a\ntheoretical study of near-field thermal radiation between suspended TBLG with a\nfocus on the magic angle. Within the chirally symmetric continuum model, we\nobserve a suppressed heat flow when approaching the magic angle owing to a\nreduced Drude weight, with greater suppressions at lower temperatures and\nlarger gap sizes. When the chemical potential lies in the energy gap near the\ncharge neutrality point, more than 100-fold heat-flow variation can be achieved\nat 50 K within 0.25{\\deg}of twist. By reducing the electron scattering rate,\nthe radiation spectrum near the magic angle dramatically narrows, leading to\nover 10,000-fold of suppression. In addition, supported TBLG is briefly\nconsidered to facilitate experimental measurement. With rationally tailored\nsubstrates, the heat-flow contrast can still exceed 1000. We also discuss\nlattice relaxation effect in terms of the interlayer coupling energy, finding\nthat a stronger coupling leads to a smaller heat-flow contrast and more\nprominent multiband transport. Our results highlight the great potential of\nmagic-angle TBLG in thermal transport, especially for controlling thermal\nradiation."
    },
    {
        "anchor": "Excitonic spectral features in strongly-coupled organic polaritons: Starting from a microscopic model, we investigate the optical spectra of\nmolecules in strongly-coupled organic microcavities examining how they might\nself-consistently adapt their coupling to light. We consider both rotational\nand vibrational degrees of freedom, focusing on features which can be seen in\nthe peak in the center of the spectrum at the bare excitonic frequency. In both\ncases we find that the matter-light coupling can lead to a self-consistent\nchange of the molecular states, with consequent temperature-dependent\nsignatures in the absorption spectrum. However, for typical parameters, these\neffects are much too weak to explain recent measurements. We show that another\nmechanism which naturally arises from our model of vibrationally dressed\npolaritons has the right magnitude and temperature dependence to be at the\norigin of the observed data.",
        "positive": "Quantum interference in finite-size mesoscopic rings: The Ginzburg-Landau theory is used to model the order parameter of a\nfinite-size mesoscopic ring to investigate the effects of the onset of\nscreening currents on the transport of incoming ones. The magnetic flux breaks\nthe symmetry of currents between input and output stubs by means of an induced\nspatial ordering upon diamagnetic and paramagnetic supercurrents circulating in\nthe ring. The distribution of those screening currents drives the interference\nof incoming/outgoing supercurrents resulting into a sinusoidal variation of\nresistance as a function of the magnetic flux even if the density of\nquasiparticles is not modified by the external magnetic field."
    },
    {
        "anchor": "Focused-ion-beam milling based nanostencil mask fabrication for spin\n  transfer torque studies: Focused-ion-beam milling is used to fabricate nanostencil masks suitable for\nthe fabrication of magnetic nanostructures relevant for spin transfer torque\nstudies. Nanostencil masks are used to define the device dimensions prior to\nthe growth of the thin film stack. They consist of a wet etch resistant top\nlayer and an insulator on top of a pre-patterned bottom electrode. The\ninsulator supports a hard mask and gives rise to an undercut by its selective\netching. The approach is demonstrated by fabricating current perpendicular to\nthe plane Co/Cu/Co nanopillar junctions, which exhibit current-induced\nmagnetization dynamics.",
        "positive": "Emergent anisotropy in magnetic metamaterials: We demonstrate directional dependence of the self-modification of internal\nmesospin textures in magnetic metamaterials, arising from the coupling of the\natomic- and mesoscopic length-scales. Dressing the mesospins in different\ndirections enables the quantification of the degree of texture in the internal\nmagnetization and its impact on the interaction energy of the mesospins. The\nemerging anisotropy is manifested in a directional dependence of the remanent\nmagnetization with temperature."
    },
    {
        "anchor": "Landau Zener transitions in a dissipative environment: Numerically exact\n  results: We study Landau-Zener transitions in a dissipative environment by means of\nthe numerically exact quasiadiabatic propagator path-integral. It allows to\ncover the full range of the involved parameters. We discover a nonmonotonic\ndependence of the transition probability on the sweep velocity which is\nexplained in terms of a simple phenomenological model. This feature, not\ncaptured by perturbative approaches, results from a nontrivial competition\nbetween relaxation and the external sweep.",
        "positive": "Morse theory study on the evolution of nodal lines in\n  $\\mathcal{PT}$-symmetric nodal-line semimetals: A nodal-line semimetal is a topological gapless phase containing\none-dimensional degeneracies called nodal lines. The nodal lines are deformed\nby a continuous change of the system such as pressure and they can even change\ntheir topology, but it is not systematically understood what kind of changes of\ntopology of nodal lines are possible. In this paper, we classify the events of\ntopology change of nodal lines by the Morse theory and reveal that only three\ntypes of topology changes of nodal lines, i.e., creation, reconnection, and\nannihilation, are possible in the spinless nodal-line semimetal protected by\ninversion and time-reversal symmetries. They are characterized by an index\nhaving the values 0, 1, and 2 for the above three types in the Morse theory.\nMoreover, we extend our theory to systems with rotational symmetries and mirror\nsymmetry and disclose the possible events of topology change of nodal lines\nunder each symmetry."
    },
    {
        "anchor": "Fluctuation Theorem for a Small Engine and Magnetization Switching by\n  Spin Torque: We consider a reversal of the magnetic moment of a nano-magnet by the\nfluctuating spin-torque induced by a non-equilibrium current of electron spins.\nThis is an example of the problem of the escape of a particle from a metastable\nstate subjected to a fluctuating non-conservative force. The spin-torque is the\nnon-conservative force and its fluctuations are beyond the description of the\nfluctuation-dissipation theorem. We estimate the joint probability distribution\nof work done by the spin torque and the Joule heat generated by the current,\nwhich satisfies the fluctuation theorem for a small engine. We predict a\nthreshold voltage above which the spin-torque shot noise induces probabilistic\nswitching events and below which such events are blocked. We adopt the theory\nof the full-counting statistics under the adiabatic pumping of spin angular\nmomentum. This enables us to account for the backaction effect, which is\ncrucial to maintain consistency with the fluctuation theorem.",
        "positive": "Attractive interactions, molecular complexes, and polarons in coupled\n  dipolar exciton fluids: Dipolar (or spatially indirect) excitons (IXs) in semiconductor double\nquantum well (DQW) subjected to an electric field are neutral species with a\ndipole moment oriented perpendicular to the DQW plane. Here, we theoretically\nstudy interactions between IXs in stacked DQW bilayers, where the dipolar\ncoupling can be either attractive or repulsive depending on the relative\npositions of the particles. By using microscopic band structure calculations to\ndetermine the electronic states forming the excitons, we show that the\nattractive dipolar interaction between stacked IXs deforms their electronic\nwave function, thereby increasing the inter-DQW interaction energy and making\nthe IX electrically polarizable. Many-particle effects interaction are\naddressed by considering the coupling between a single IX in one of the DQWs to\na cloud of IXs in the other DQW, which is modeled either as a closed-packed\nlattice or as a continuum IX fluid. We find that the lattice model yields IX\ninterlayer binding energies decreasing with increasing lattice density. This\nbehavior is due to the dominating role of the intra-DQW dipolar repulsion,\nwhich prevents more than one exciton from entering the attractive region of the\ninter-DQW coupling. Finally, both models shows that the single IX distorts the\ndistribution of IXs in the adjacent DQW, thus inducing the formation of an IX\npolaron. While the interlayer binding energy reduces with IX density for\nlattice polarons, the continuous polaron model predicts a non-monotonous\ndependence on density in semi-quantitative agreement with a recent experimental\nstudy [cf. Hubert {\\it et al.}, Phys. Rev. {\\bf X}9, 021026 (2019)]."
    },
    {
        "anchor": "Geometric orbital susceptibility: quantum metric without Berry curvature: The orbital magnetic susceptibility of an electron gas in a periodic\npotential depends not only on the zero field energy spectrum but also on the\ngeometric structure of cell-periodic Bloch states which encodes interband\neffects. In addition to the Berry curvature, we explicitly relate the orbital\nsusceptibility of two-band models to a quantum metric tensor defining a\ndistance in Hilbert space. Within a simple tight-binding model allowing for a\ntunable Bloch geometry, we show that interband effects are essential even in\nthe absence of Berry curvature. We also show that for a flat band model, the\nquantum metric gives rise to a very strong orbital paramagnetism.",
        "positive": "Superconducting nano-mechanical diamond resonators: In this work we present the fabrication and characterization of\nsuperconducting nano-mechanical resonators made from nanocrystalline boron\ndoped diamond (BDD). The oscillators can be driven and read out in their\nsuperconducting state and show quality factors as high as 40,000 at a resonance\nfrequency of around 10 MHz. Mechanical damping is studied for magnetic fields\nup to 3 T where the resonators still show superconducting properties. Due to\ntheir simple fabrication procedure, the devices can easily be coupled to other\nsuperconducting circuits and their performance is comparable with\nstate-of-the-art technology."
    },
    {
        "anchor": "Broad-Wavevector Spin Pumping of Flat-Band Magnons: We report the experimental observation of large spin pumping signals in\nYIG/Pt system driven by broad-wavevector spin-wave spin current. 280 nm-wide\nmicrowave inductive antennas offer broad-wavevector excitation which, in\ncombination with quasi-flatband of YIG, allows a large number of magnons to\nparticipate in spin pumping at a given frequency. Through comparison with\nferromagnetic resonance spin pumping, we attribute the enhancement of the spin\ncurrent to the multichromatic magnons. The high efficiency of spin current\ngeneration enables us to uncover nontrivial propagating properties in ultra-low\npower regions. Additionally, our study achieves the spatially separated\ndetection of magnons, allowing the direct extraction of the decay length. The\nsynergistic combination of the capability of broad-wavevector excitation,\nenhanced voltage signals, and nonlocal detection provides a new avenue for the\nelectrical exploration of spin waves dynamics.",
        "positive": "Valley detection using a graphene gradual pn junction with spin-orbit\n  coupling: an analytical conductance calculation: Graphene pn junction is the brick to build up variety of graphene\nnano-structures. The analytical formula of the conductance of graphene gradual\npn junctions in the whole bipolar region has been absent up to now. In this\npaper, we analytically calculated that pn conductance with the spin-orbit\ncoupling and stagger potential taken into account. Our analytical expression\nindicates that the energy gap causes the conductance to drop a constant value\nwith respect to that without gap in a certain parameter region, and manifests\nthat the curve of the conductance versus the stagger potential consists of two\nGaussian peaks -- one valley contributes one peak. The latter feature allows\none to detect the valley polarization without using double-interface resonant\ndevices."
    },
    {
        "anchor": "Large Cumulant Eigenvalue as a Signature of Exciton Condensation: The Bose-Einstein condensation of excitons into a single quantum state is\nknown as exciton condensation. Exciton condensation, which potentially supports\nthe frictionless flow of energy, has recently been realized in graphene\nbilayers and van der Waals heterostructures. Here we show that exciton\ncondensates can be predicted from a combination of reduced density matrix\ntheory and cumulant theory. We show that exciton condensation occurs if and\nonly if there exists a large eigenvalue in the cumulant part of the\nparticle-hole reduced density matrix. In the thermodynamic limit we show that\nthe large eigenvalue is bounded from above by the number of excitons. In\ncontrast to the eigenvalues of the particle-hole matrix, the large eigenvalue\nof the cumulant matrix has the advantage of providing a size-extensive measure\nof the extent of condensation. Here we apply this signature to predict exciton\ncondensation in both the Lipkin model and molecular stacks of benzene. The\ncomputational signature has applications to the prediction of exciton\ncondensation in both molecules and materials.",
        "positive": "Hole spin in tunable Ge hut wire double quantum dot: Holes in germanium (Ge) exhibit strong spin-orbit interaction, which can be\nexploited for fast and all-electrical manipulation of spin states. Here, we\nreport transport experiments in a tunable Ge hut wire hole double quantum dot.\nWe observe the signatures of Pauli spin blockade (PSB) with a large\nsinglet-triplet energy splitting of ~1.1 meV and extract the g factor. By\nanalyzing the the PSB leakage current, we obtain a spin-orbit length l_so of ~\n40-100 nm. Furthermore, we demonstrate the electric dipole spin resonance.\nThese results lay a solid foundation for implementing high quality tunable hole\nspin-orbit qubits."
    },
    {
        "anchor": "3D reconstruction of the magnetization vector via XMCD-PEEM: In this work we present a detailed analysis on the performance of X-ray\nmagnetic circular dichroism photo-emission electron microscopy (XMCD-PEEM) as a\ntool for vector reconstruction of the magnetization. For this, we choose\n360$^{\\circ}$ domain wall ring structures which form in a synthetic\nantiferromagnet as our model to conduct the quantitative analysis. We assess\nhow the quality of the results is affected depending on the number of\nprojections that are involved in the reconstruction process, as well as their\nangular distribution. For this we develop a self-consistent error metric, which\nindicates that the main factor of improvement comes from selecting the\nprojections evenly spread out in space, over having a larger number of these\nspanning a smaller angular range. This work thus poses XMCD-PEEM as a powerful\ntool for vector imaging of complex 3D magnetic structures.",
        "positive": "Interlayer Decoupling in 30\u00b0 Twisted Bilayer Graphene Quasicrystal: Stacking order has strong influence on the coupling between the two layers of\ntwisted bilayer graphene (BLG), which in turn determines its physical\nproperties. Here, we report the investigation of the interlayer coupling of the\nepitaxially grown single-crystal 30{\\deg} twisted BLG on Cu(111) at the atomic\nscale. The stacking order and morphology of BLG is controlled by a rationally\ndesigned two-step growth process, that is, the thermodynamically controlled\nnucleation and kinetically controlled growth. The crystal structure of the\n30{\\deg}-twisted bilayer graphene (30{\\deg}-tBLG) is determined to have the\nquasicrystal like symmetry. The electronic properties and interlayer coupling\nof the 30{\\deg}-tBLG is investigated using scanning tunneling microscopy (STM)\nand spectroscopy (STS). The energy-dependent local density of states (DOS) with\nin-situ electrostatic doping shows that the electronic states in two graphene\nlayers are decoupled near the Dirac point. A linear dispersion originated from\nthe constituent graphene monolayers is discovered with doubled degeneracy. This\nstudy contributes to controlled growth of twist-angle-defined BLG, and provides\ninsights of the electronic properties and interlayer coupling in this\nintriguing system."
    },
    {
        "anchor": "Finite-temperature conductance of strongly interacting quantum wire with\n  a nuclear spin order: We study the temperature dependence of the electrical conductance of a clean\nstrongly interacting quantum wire in the presence of a helical nuclear spin\norder. The nuclear spin helix opens a temperature-dependent partial gap in the\nelectron spectrum. Using a bosonization framework we describe the gapped\nelectron modes by sine-Gordon-like kinks. We predict an internal resistivity\ncaused by an Ohmic-like friction these kinks experience via interacting with\ngapless excitations. As a result, the conductance rises from $G=e^2/h$ at\ntemperatures below the critical temperature when nuclear spins are fully\npolarized to $G=2e^2/h$ at higher temperatures when the order is destroyed,\nfeaturing a relatively wide plateau in the intermediate regime. The theoretical\nresults are compared with the experimental data for GaAs quantum wires obtained\nrecently by Scheller et al. [Phys. Rev. Lett. 112, 066801 (2014)].",
        "positive": "Effective theory of monolayer TMDC double quantum dots: Monolayer Transition Metal Dichalcogenides (TMDCs) are promising candidates\nfor quantum technologies, such as quantum dots, because they are truly\ntwo-dimensional semiconductors with a direct band gap. In this work, we analyse\ntheoretically the behaviour of a double quantum dot (DQD) system created in the\nconduction band of these materials, with two electrons in the (1,1) charge\nconfiguration. Motivated by recent experimental progress, we consider several\nscenarios, including different spin-orbit splittings in the two dots and\nincluding the case when the valley degeneracy is lifted due to an insulating\nferromagnetic substrate. Finally, we discuss in which cases it is possible to\nreduce the low energy subspace to the lowest Kramers pairs. We find that in\nthis case the low energy model is formally identical to the Heisenberg exchange\nHamiltonian."
    },
    {
        "anchor": "Mesoscopic quantum measurements: The paper discusses dynamics of quantum measurements in mesoscopic\nsolid-state systems. The aim is to show how the general ideas of the quantum\nmeasurement theory play out in the realistic models of actual mesoscopic\ndetectors. The two general models of ballistic and tunneling detectors are\ndescribed and studied quantitatively. Simple transformation cycle demonstrating\nwavefunction reduction in a mesosocpic qubit is suggested.",
        "positive": "Strong coupling between a photon and a hole spin in silicon: Spins in semiconductor quantum dots constitute a promising platform for\nscalable quantum information processing. Coupling them strongly to the photonic\nmodes of superconducting microwave resonators would enable fast non-demolition\nreadout and long-range, on-chip connectivity, well beyond nearest-neighbor\nquantum interactions. Here we demonstrate strong coupling between a microwave\nphoton in a superconducting resonator and a hole spin in a silicon-based double\nquantum dot issued from a foundry-compatible MOS fabrication process. By\nleveraging the strong spin-orbit interaction intrinsically present in the\nvalence band of silicon, we achieve a spin-photon coupling rate as high as\n330~MHz largely exceeding the combined spin-photon decoherence rate. This\nresult, together with the recently demonstrated long coherence of hole spins in\nsilicon, opens a new realistic pathway to the development of circuit quantum\nelectrodynamics with spins in semiconductor quantum dots."
    },
    {
        "anchor": "Thermometry and memcapacitance with qubit-resonator system: We study theoretically dynamics of a driven-dissipative qubit-resonator\nsystem. Specifically, a transmon qubit is coupled to a transmission-line\nresonator; this system is considered to be probed via a resonator, by means of\neither continuous or pulsed measurements. Analytical results obtained in the\nsemiclassical approximation are compared with calculations in the semi-quantum\ntheory as well as with the previous experiments. We demonstrate that the\ntemperature dependence of the resonator frequency shift can be used for the\nsystem thermometry and that the dynamics, displaying pinched-hysteretic curve,\ncan be useful for realization of memory devices, the quantum memcapacitors.",
        "positive": "Electric-field-tunable mechanical properties of relaxor ferroelectric\n  single crystal measured by nanoindentation: Electric field dependent mechanical properties of relaxor ferroelectric\nmaterial Pb(Mn1/3Nb2/3)O3-PbTiO3 are investigated with the nanoindentation\ntechnique. Giant electric-field-tunable apparent elastic modulus (up to -39%),\nhardness (-9% to 20%) and energy dissipation (up to -13%) are reported. Based\non experimental data, a characterization method of electromechanical coupled\nnanoindentation is proposed. In this method, an electric field tunable scaling\nrelationship among elastic modulus, hardness and indentation work for\nferroelectric materials can be determined. In addition, this method can be used\nto obtain the electric-field-dependent elastic modulus and hardness, and avoid\nthe estimate of contact area in the Oliver-Pharr method. Finally, the different\neffects on elastic modulus between positive and negative electric fields can be\nexplained by the flexoelectric effect."
    },
    {
        "anchor": "Nanomechanical resonant structures in single-crystal diamond: With its host of outstanding material properties, single-crystal diamond is\nan attractive material for nanomechanical systems. Here, the mechanical\nresonance characteristics of freestanding, single-crystal diamond nanobeams\nfabricated by an angled-etching methodology are reported. Resonance frequencies\ndisplayed evidence of significant compressive stress in doubly clamped diamond\nnanobeams, while cantilever resonance modes followed the expected\ninverse-length-squared trend. Q-factors on the order of 104 were recorded in\nhigh vacuum. Results presented here represent initial groundwork for future\ndiamond-based nanomechanical systems which may be applied in both classical and\nquantum applications.",
        "positive": "Non-Resonant Below-Bandgap Two-Photon Absorption in Quantum Dot Solar\n  Cells: We are the first to show with clear experimental results that photons that\nhave energy lower than the transition energy between quantum dots states and\nvalance band can still contribute greatly to the photocurrent via both\none-photon absorption process (1PA) and two-photon absorption process (2PA).\nThe tailing states function as both the energy states for low energy photon\nabsorption and the photocarriers extraction pathway. One of the biggest\nadvantages of our method is that it can clearly differentiate the photocurrent\ndue to 1PA process and 2PA process. Both 1PA and 2PA photocurrent generation\nefficiency in an InAs/GaAs QD device with photon excitation at 1550 nm have\nbeen quantitatively evaluated."
    },
    {
        "anchor": "Interpreting motion and force for narrow-band intermodulation atomic\n  force microscopy: Intermodulation atomic force microscopy (ImAFM) is a mode of dynamic atomic\nforce microscopy that probes the nonlinear tip-surface force by measurement of\nthe mixing of multiple tones in a frequency comb. A high $Q$ cantilever\nresonance and a suitable drive comb will result in tip motion described by a\nnarrow-band frequency comb. We show by a separation of time scales, that such\nmotion is equivalent to rapid oscillations at the cantilever resonance with a\nslow amplitude and phase or frequency modulation. With this time domain\nperspective we analyze single oscillation cycles in ImAFM to extract the\nFourier components of the tip-surface force that are in-phase with tip motion\n($F_I$) and quadrature to the motion ($F_Q$). Traditionally, these force\ncomponents have been considered as a function of the static probe height only.\nHere we show that $F_I$ and $F_Q$ actually depend on both static probe height\nand oscillation amplitude. We demonstrate on simulated data how to reconstruct\nthe amplitude dependence of $F_I$ and $F_Q$ from a single ImAFM measurement.\nFurthermore, we introduce ImAFM approach measurements with which we reconstruct\nthe full amplitude and probe height dependence of the force components $F_I$\nand $F_Q$, providing deeper insight into the tip-surface interaction. We\ndemonstrate the capabilities of ImAFM approach measurements on a polystyrene\npolymer surface.",
        "positive": "Phonon Confinement and Transport in Ultrathin Films: Thermal transport by phonons in films with thicknesses of less than 10 nm is\ninvestigated in a soft system (Lennard-Jones argon) and a stiff system (Tersoff\nsilicon) using two-dimensional lattice dynamics calculations and the Boltzmann\ntransport equation. This approach uses a unit cell that spans the film\nthickness, which removes approximations related to the finite cross-plane\ndimension required in typical three-dimensional-based approaches. Molecular\ndynamics simulations are performed to obtain finite-temperature structures for\nthe lattice dynamics calculations and to predict thermal conductivity\nbenchmarks. Thermal conductivity decreases with decreasing film thickness until\nthe thickness reaches four unit cells (2.1 nm) for argon and three unit cells\n(1.6 nm) for silicon. With a further decrease in film thickness, thermal\nconductivity plateaus in argon while it increases in silicon. This unexpected\nbehavior, which we identify as a signature of phonon confinement, is a result\nof an increased contribution from low-frequency phonons, whose density of\nstates increases as the film thickness decreases. Phonon mode-level analysis\nsuggests that confinement effects emerge below thicknesses of ten unit cells\n(5.3 nm) for argon and six unit cells (3.2 nm) for silicon. Thermal\nconductivity predictions based on the bulk phonon properties combined with a\nboundary scattering model do not capture the low thickness behavior. To match\nthe two-dimensional lattice dynamics and molecular dynamics predictions for\nlarger thicknesses, the three-dimensional lattice dynamics calculations require\na finite specularity parameter that in some cases approaches unity. These\nfindings point to the challenges associated with interpreting experimental\nthermal conductivity measurements of ultrathin silicon films, where surface\nroughness and a native oxide layer impact phonon transport."
    },
    {
        "anchor": "A first-principles study of tunneling magnetoresistance in\n  Fe/MgAl2O4/Fe(001) magnetic tunnel junctions: We investigated the spin-dependent transport properties of Fe/MgAl2O4/Fe(001)\nmagnetic tunneling junctions (MTJs) on the basis of first-principles\ncalculations of the electronic structures and the ballistic conductance. The\ncalculated tunneling magnetoresistance (TMR) ratio of a Fe/MgAl2O4/Fe(001) MTJ\nwas about 160%, which was much smaller than that of a Fe/MgO/Fe(001) MTJ\n(1600%) for the same barrier thickness. However, there was an evanescent state\nwith delta 1 symmetry in the energy gap around the Fermi level of normal spinel\nMgAl2O4, indicating the possibility of a large TMR in Fe/MgAl2O4/Fe(001) MTJs.\nThe small TMR ratio of the Fe/MgAl2O4/Fe(001) MTJ was due to new conductive\nchannels in the minority spin states resulting from a band-folding effect in\nthe two-dimensional (2-D) Brillouin zone of the in-plane wave vector (k//) of\nthe Fe electrode. Since the in-plane cell size of MgAl2O4 is twice that of the\nprimitive in-plane cell size of bcc Fe, the bands in the boundary edges are\nfolded, and minority-spin states coupled with the delta 1 evanescent state in\nthe MgAl2O4 barrier appear at k//=0, which reduces the TMR ratio of the MTJs\nsignificantly.",
        "positive": "Dual Origin of Room Temperature Sub-Terahertz Photoresponse in Graphene\n  Field Effect Transistors: Graphene is considered as a promising platform for detectors of\nhigh-frequency radiation up to the terahertz (THz) range due to graphene$'$s\nsuperior electron mobility. Previously it has been shown that graphene field\neffect transistors (FETs) exhibit room temperature broadband photoresponse to\nincoming THz radiation thanks to the thermoelectric and/or plasma wave\nrectification. Both effects exhibit similar functional dependences on the gate\nvoltage and therefore it was found to be difficult to disentangle these\ncontributions in the previous studies. In this letter, we report on combined\nexperimental and theoretical studies of sub-THz response in graphene\nfield-effect transistors analyzed at different temperatures. This\ntemperature-dependent study allowed us to reveal the role of\nphoto-thermoelectric effect, p-n junction rectification, and plasmonic\nrectification in the sub-THz photoresponse of graphene FETs."
    },
    {
        "anchor": "Equilibration of Quasi-One-Dimensional Fermi Gases: One-dimensional systems often possess multiple channels or bands arising from\nthe excitation of transverse degrees of freedom. In the present work, we study\nthe specific processes that dominate the equilibration of multi-channel Fermi\ngases at low temperatures. Focusing on the case of two channels, we perform an\nanalysis of the relaxation properties of these systems by studying the spectrum\nand eigenmodes of the linearized collision integral. As an application of this\nanalysis, a detailed calculation of the bulk viscosity is presented. The\ndominant scattering processes obey an unexpected conservation law which is\nlikely to affect the hydrodynamic behavior of these systems.",
        "positive": "Magneto-transport characteristics of a 2D electron system driven to\n  negative magneto-conductivity by microwave photoexcitation: Negative diagonal magneto-conductivity/resistivity is a spectacular- and\nthought provoking- property of driven, far-from-equilibrium, low dimensional\nelectronic systems. The physical response of this exotic electronic state is\nnot yet fully understood since it is rarely encountered in experiment. The\nmicrowave-radiation-induced zero-resistance state in the high mobility\nGaAs/AlGaAs 2D electron system is believed to be an example where negative\nmagneto-conductivity/resistivity is responsible for the observed phenomena.\nHere, we examine the magneto-transport characteristics of this negative\nconductivity/resistivity state in the microwave photo-excited two-dimensional\nelectron system (2DES) through a numerical solution of the associated boundary\nvalue problem. The results suggest, surprisingly, that a bare negative diagonal\nconductivity/resistivity state in the 2DES under photo-excitation should yield\na positive diagonal resistance with a concomitant sign reversal in the Hall\nvoltage."
    },
    {
        "anchor": "Influence of Magnetic Field on Effective Electron-Electron Interactions\n  in a Copper Wire: We have measured in a copper wire the energy exchange rate between\nquasiparticles as a function of the applied magnetic field. We find that the\neffective electron-electron interaction is strongly modified by the magnetic\nfield, suggesting that magnetic impurities play a role on the interaction\nprocesses.",
        "positive": "Coherent optical control of the spin of a single hole in a quantum dot: We demonstrate coherent optical control of a single hole spin confined to an\nInAs/GaAs quantum dot. A superposition of hole spin states is created by fast\n(10-100 ps) dissociation of a spin-polarized electron-hole pair. Full control\nof the hole-spin is achieved by combining coherent rotations about two axes:\nLarmor precession of the hole-spin about an external Voigt geometry magnetic\nfield, and rotation about the optical-axis due to the geometric phase shift\ninduced by a picosecond laser pulse resonant with the hole-trion transition."
    },
    {
        "anchor": "Electron heating and mechanical properties of graphene: The heating of electrons in graphene by laser irradiation, and its effects on\nthe lattice structure, are studied. Values for the temperature of the electron\nsystem in realistic situations are obtained. For sufficiently high electron\ntemperatures, the occupancy of the states in the $\\sigma$ band of graphene is\nmodified. The strength of the carbon-carbon bonds changes, leading to the\nemergence of strains, and to buckling in suspended samples. While most\napplications of `strain engineering' in two dimensional materials focus on the\neffects of strains on electronic properties, the effect studied here leads to\nalterations of the structure induced by light. This novel optomechanical\ncoupling can induce deflections in the order of $\\sim 50$ nm in micron size\nsamples.",
        "positive": "Berryogenesis: self-induced Berry flux and spontaneous non-equilibrium\n  magnetism: Spontaneous symmetry breaking is central to the description of interacting\nphases of matter. Here we reveal a new mechanism through which a driven\ninteracting system subject to a time-reversal symmetric driving field can\nspontaneously magnetize. We show that the strong internal ac fields of a metal\ndriven close to its plasmon resonance may enable Berryogenesis: the spontaneous\ngeneration of a self-induced Bloch band Berry flux. The self-induced Berry flux\nsupports and is sustained by a circulating plasmonic motion, which may arise\neven for a linearly polarized driving field. This non-equilibrium phase\ntransition occurs above a critical driving amplitude, and may be of either\ncontinuous or discontinuous type. Berryogenesis relies on feedback due to\ninterband coherences induced by internal fields, and may readily occur in a\nwide variety of multiband systems. We anticipate that graphene devices, in\nparticular, provide a natural platform to achieve Berryogenesis and\nplasmon-mediated spontaneous non-equilibrium magnetization in present-day\ndevices."
    },
    {
        "anchor": "Peltier effect induced longitudinal resistivity of ideal 2D\n  electron(hole) gas in strong magnetic field: We demonstrate that in strong quantum limit the thermoelectric Peltier effect\ncould define the longitudinal resistivity of dissipationless two-dimensional\nelectron(hole) gas. The current results in heating(cooling) at first(second)\nHall bar sample contact due to Peltier effect. At small current the contacts\ntemperatures are different, the temperature gradient is linear on current. The\nvoltage swing downstream the current is proportional to Peltier effect induced\nthermopower. As a result, nonzero longitudinal resistivity is measured in\nexperiment. The above effect could exist in 3D case.",
        "positive": "Phase and periodicity of Aharonov-Bohm oscillations: effect of channel\n  mixing: We take a negative delta function impurity in one arm of a quasi one\ndimensional Aharonov-Bohm ring and demonstrate abrupt phase changes across a\nquasi bound state of the negative delta function potential. We give a new\nmechanism for conductance oscillations with the strength of the negative delta\npotential. We also show that coupling to evanescent modes can result in a\n$hc/2e$ flux periodicity at certain energies. These observations were made in a\nrecent ingenious experiment by D. Mailly et al [1]."
    },
    {
        "anchor": "Superconductivity in rhombohedral trilayer graphene: We report the observation of superconductivity in rhombohedral trilayer\ngraphene electrostatically doped with holes. Superconductivity occurs in two\ndistinct regions within the space of gate-tuned charge carrier density and\napplied electric displacement field, which we denote SC1 and SC2. The high\nsample quality allows for detailed mapping of the normal state Fermi surfaces\nby quantum oscillations, which reveal that in both cases superconductivity\narises from a normal state described by an annular Fermi sea that is proximal\nto an isospin symmetry breaking transition where the Fermi surface degeneracy\nchanges. The upper out-of-plane critical field $B_{C\\perp}\\approx 10\n\\mathrm{mT}$ for SC1 and $1\\mathrm{mT}$ for SC2, implying coherence lengths\n$\\xi$ of 200nm and 600nm, respectively. The simultaneous observation of\ntransverse magnetic electron focusing implies a mean free path\n$\\ell\\gtrsim3.5\\mathrm{\\mu m}$. Superconductivity is thus deep in the clean\nlimit, with the disorder parameter $d=\\xi/\\ell<0.1$. SC1 emerge from a\nparamagnetic normal state and is suppressed with in-plane magnetic fields in\nagreement with the Pauli paramagnetic limit. In contrast, SC2 emerges from a\nspin-polarized, valley-unpolarized half-metal. Measurements of the in-plane\ncritical field show that this superconductor exceeds the Pauli limit by at\nleast one order of magnitude. We discuss our results in light of several\nmechanisms including conventional phonon-mediated pairing, pairing due to\nfluctuations of the proximal isospin order, and intrinsic instabilities of the\nannular Fermi liquid. Our observation of superconductivity in a clean and\nstructurally simple two-dimensional metal hosting a variety of gate tuned\nmagnetic states may enable a new class of field-effect controlled mesoscopic\nelectronic devices combining correlated electron phenomena.",
        "positive": "Spontaneous edge-defect formation and defect-induced conductance\n  suppression in graphene nanoribbons: We present a first-principles study of the migration and recombination of\nedge defects (carbon adatom and/or vacancy) and their influence on electrical\nconductance in zigzag graphene nanoribbons (ZGNRs). It is found that at room\ntemperature, the adatom is quite mobile while the vacancy is almost immobile\nalong the edge of ZGNRs. The recombination of an adatom-vacancy pair leads to a\npentagon-heptagon ring defect structure having a lower energy than the perfect\nedge, implying that such an edge-defect can be formed spontaneously. This edge\ndefect can suppresses the conductance of ZGNRs drastically, which provides some\nuseful hints for understanding the observed semiconducting behavior of the\nfabricated narrow GNRs."
    },
    {
        "anchor": "Geometric spin-orbit coupling and chirality-induced spin selectivity: We report a new type of spin-orbit coupling (SOC) called geometric SOC.\nStarting from the relativistic theory in curved space, we derive an effective\nnonrelativistic Hamiltonian in a generic curve embedded into flat three\ndimensions. The geometric SOC is $O(m^{-1})$, in which $m$ is the electron\nmass, and hence much larger than the conventional SOC of $O(m^{-2})$. The\nenergy scale is estimated to be a hundred meV for a nanoscale helix. We\ncalculate the current-induced spin polarization in a coupled-helix model as a\nrepresentative of the chirality-induced spin selectivity. We find that it\ndepends on the chirality of the helix and is of the order of $0.01 \\hbar$ per\n${\\rm nm}$ when a charge current of $1~{\\rm \\mu A}$ is applied.",
        "positive": "Spin currents of exciton polaritons in a microcavity with (110)-oriented\n  quantum well: We study the polarization optical properties of microcavities with embedded\n(110)-oriented quantum wells. The spin dynamics of exciton polaritons in such\nstructures is governed by the interplay of the spin-orbit splitting of exciton\nstates, which is odd in the in-plane momentum, and the longitudinal-transverse\nsplitting of cavity modes, which is even in the momentum. We demonstrate the\ngeneration of polariton spin currents by linearly polarized optical pump and\nanalyze the arising polariton spin textures in the cavity plane. Tuning the\nexcitation spot size, which controls the polariton distribution in the momentum\nspace, one obtains symmetric or asymmetric spin textures."
    },
    {
        "anchor": "Spin characterization and control over the regime of radiation-induced\n  zero-resistance states: Over the regime of the radiation-induced zero-resistance states and\nassociated oscillatory magnetoresistance, we propose a low magnetic field\nanalog of quantum-Hall-limit techniques for the electrical detection of\nelectron spin- and nuclear magnetic- resonance, dynamical nuclear polarization\nvia electron spin resonance, and electrical characterization of the nuclear\nspin polarization via the Overhauser shift. In addition, beats observed in the\nradiation-induced oscillatory-magnetoresistance are developed into a method to\nmeasure and control the zero-field spin splitting due to the Bychkov-Rashba and\nbulk inversion asymmetry terms in the high mobility GaAs/AlGaAs system.",
        "positive": "Capacitor physics in ultra-near-field heat transfer: Using the nonequilibrium Green's function (NEGF) formalism, we propose a\nmicroscopic theory for near-field heat transfer between charged metal plates\nfocusing on the Coulomb interactions. Tight-binding models for the electrons\nare coupled to the electromagnetic field continuum through a scalar potential.\nOur approach differs from the established ones based on Rytov fluctuational\nelectrodynamics, which deals with the transverse radiative field and vector\npotential. For a two quantum-dot model a new length scale emerges below which\nthe heat current exhibits great enhancement. This length scale is related to\nthe physics of parallel plate capacitors. At long distances $d$, the energy\nflux decreases as $1/d^2$."
    },
    {
        "anchor": "Rational design principles of quantum anomalous Hall effect from\n  superlattice-like magnetic topological insulators: As one of paradigmatic phenomena in condensed matter physics, the quantum\nanomalous Hall effect (QAHE) in stoichiometric Chern insulators has drawn great\ninterest for years. By using model Hamiltonian analysis and first-principle\ncalculations, we establish a topological phase diagram and map on it with\ndifferent two-dimensional configurations, which is taken from the\nrecently-grown magnetic topological insulators MnBi4Te7 and MnBi6Te10 with\nsuperlattice-like stacking patterns. These configurations manifest various\ntopological phases, including quantum spin Hall effect with and without\ntime-reversal symmetry, as well as QAHE. We then provide design principles to\ntrigger QAHE by tuning experimentally accessible knobs, such as slab thickness\nand magnetization. Our work reveals that superlattice-like magnetic topological\ninsulators with tunable exchange interaction serve as an ideal platform to\nrealize the long-sought QAHE in pristine compounds, paving a new avenue within\nthe area of topological materials.",
        "positive": "Uniform Peak Optical Conductivity in Single-Walled Carbon Nanotubes: Recent measurements in single-walled carbon nanotubes show that, on\nresonance, all nanotubes display the same peak optical conductivity of\napproximately 8 $e^2/h$, independent of radius or chirality [Joh \\emph{et al.},\n\\emph{Nature Nanotechnology} \\textbf{6}, 51 (2011)]. We show that this uniform\npeak conductivity is a consequence of the relativistic band structure and\nstrength of the Coulomb interaction in carbon nanotubes. We further construct a\nminimalist model of exciton dynamics that describes the general phenomenology\nand provides an accurate prediction of the numerical value of the peak optical\nconductivity. The work illustrates the need for careful treatment of relaxation\nmechanisms in modeling the optoelectronic properties of carbon nanotubes."
    },
    {
        "anchor": "Noncollinear magnetism and half-metallicity in biased bilayer zigzag\n  graphene nanoribbons: We study in this paper the edge polarizations and their consequences for a\nbiased Bernal stacked bilayer graphene nanoribbon with zigzag termination. The\nmagnetic states are classified according to the interlayer and intralayer\ncouplings between the edge polarizations, and the magnetic phase diagram of\ndoping versus bias voltage is given. Coplanar magnetic phase is found and the\nvariation of its magnetic structure with the bias voltage is investigated. For\nall the magnetic states, we also discuss the possibility of the\nhalf-metallicity, and for a ribbon with perfect zigzag edges we predict seven\nkinds of the half-metallic states, which are characterized by their distinct\nmagnetic structures and quantized electrical conductances along the ribbon.",
        "positive": "Spectral functions of CVD grown MoS$_2$ monolayers after chemical\n  transfer onto Au surface: The recent rise of van der Waals (vdW) crystals has opened new prospects for\nstudying versatile and exotic fundamental physics with future device\napplications such as twistronics. Even though the recent development on\nAngle-resolved photoemission spectroscopy (ARPES) with Nano-focusing optics,\nmaking clean surfaces and interfaces of chemically transferred crystals have\nbeen challenging to obtain high-resolution ARPES spectra. Here, we show that by\nemploying nano-ARPES with submicron sized beam and polystyrene-assisted\ntransfer followed by annealing process in ultra-high vacuum environment,\nremarkably clear ARPES spectral features such as spin-orbit splitting and band\nrenormalization of CVD-grown, monolayered MoS2 can be measured. Our finding\npaves a way to exploit chemically transferred crystals for measuring\nhigh-resolution ARPES spectra to observe exotic quasi-particles in vdW\nheterostructures."
    },
    {
        "anchor": "Quantized surface magnetism and higher-order topology: Application to\n  the Hopf insulator: We identify topological aspects of the subextensive magnetic moment\ncontributed by the surfaces of a three-dimensional crystallite -- assumed to be\ninsulating in the bulk as well as on all surface facets, with trivial Chern\ninvariants in the bulk. The geometric component of this subextensive moment is\ngiven by its derivative with respect to the chemical potential, at zero\ntemperature and zero field, per unit surface area, and hence corresponds to the\nsurface magnetic compressibility. The sum of the surface compressibilities\ncontributed by two opposite facets of a cube-shaped crystallite is quantized to\nan integer multiple of the fundamental constant $e/h c$; this integer is in\none-to-one correspondence with the net chirality of hinge modes on the surface\nof the crystallite, manifesting a link with higher-order topology. The\ncontribution by a single facet to the magnetic compressibility need not be\nquantized to integers; however, symmetry and/or Hilbert-space constraints can\nfix the single-facet compressibility to half-integer multiples of $e/hc$, as\nwill be exemplified by the Hopf insulator.",
        "positive": "Optimal orientation of striped states in the quantum Hall system against\n  external modulations: We study striped states in the quantum Hall system around half-filled high\nLandau levels and obtain the optimal orientation of the striped state in the\npresence of an external unidirectional periodic potential. It is shown that the\noptimal orientation is orthogonal to the external modulation in the Coulomb\ndominant regime (the orthogonal phase) and is parallel in the external\nmodulation dominant regime (the parallel phase). The phase boundary of these\ntwo phases is determined numerically in the parameter space of the strength and\nwave number of the external modulation at the half-filled third Landau level."
    },
    {
        "anchor": "Strain-induced Aharonov-Bohm effect at nanoscale and ground state of a\n  carbon nanotube with zigzag edges: Magnetic flux piercing a carbon nanotube induce periodic gap oscillations\nwhich represent the Aharonov-Bohm effect at nanoscale. Here we point out, by\nanalyzing numerically the anisotropic Hubbard model on a honeycomb lattice,\nthat similar oscillations should be observable when uniaxial strain is applied\nto a nanotube. In both cases, a vector potential (magnetic- or strain-induced)\nmay affect the measurable quantities at zero field. The analysis, carried out\nwithin the Gutzwiller Approximation, shows that for small semiconducting\nnanotube with zigzag edges and realistic value of the Hubbard repulsion\n($U/t_0=1.6$, with $t_0\\approx{}2.5\\,$eV being the equilibrium hopping\nintegral) energy gap can be reduced by a factor of more than $100$ due to the\nstrain.",
        "positive": "Weber blockade in superconducting nanowires: We have measured the critical current as a function of magnetic field in\nshort and narrow superconducting aluminum nanowires. In the range of magnetic\nfields in which vortices can enter a nanowire in a single row, we find regular\noscillations of the critical current as a function of magnetic field. The\noscillations are found to correspond to adding a single vortex to the nanowire,\nwith the number of vortices on the nanowire staying constant within each period\nof the oscillation. This effect can be thought of as a Weber blockade, and the\nnanowires act as quantum dots for vortices, analogous to the Coulomb blockade\nfor electrons in quantum dots."
    },
    {
        "anchor": "Slowest kinetic modes revealed by metabasin renormalization: Understanding the slowest relaxations of complex systems, such as relaxation\nof glass-forming materials, diffusion in nanoclusters, and folding of\nbiomolecules, is important for physics, chemistry, and biology. For a kinetic\nsystem, the relaxation modes are determined by diagonalizing its transition\nrate matrix. However, for realistic systems of interest, numerical\ndiagonalization, as well as extracting physical understanding from the\ndiagonalization results, is difficult due to the high dimensionality. Here, we\ndevelop an alternative and generally applicable method of extracting the\nlong-time scale relaxation dynamics by combining the metabasin analysis of\nOkushima et al. [Phys. Rev. E 80, 036112 (2009)] and a Jacobi method. We test\nthe method on a illustrative model of a four-funnel model, for which we obtain\na renormalized kinematic equation of much lower dimension sufficient for\ndetermining slow relaxation modes precisely. The method is successfully applied\nto the vacancy transport problem in ionic nanoparticles [Niiyama et al. Chem.\nPhys. Lett. 654, 52 (2016)], allowing a clear physical interpretation that the\nfinal relaxation consists of two successive, characteristic processes.",
        "positive": "Noise in the helical edge channel anisotropically coupled to a local\n  spin: We calculate the frequency-dependent shot noise in the edge states of a\ntwo-dimensional topological insulator coupled to a magnetic impurity with spin\n$S=1/2$ of arbitrary anisotropy. If the anisotropy is absent, the noise is\npurely thermal at low frequencies, but tends to the Poissonian noise of the\nfull current $I$ at high frequencies. If the interaction only flips the\nimpurity spin but conserves those of electrons, the noise at high voltages\n$eV\\gg T$ is frequency-independent. Both the noise and the backscattering\ncurrent $I_{bs}$ saturate at voltage-independent values. Finally, if the\nHamiltonian contains all types of non-spin-conserving scattering, the noise at\nhigh voltages becomes frequency-dependent again. At low frequencies, its ratio\nto $2eI_{bs}$ is larger than 1 and may reach 2 in the limit $I_{bs}\\to 0$. At\nhigh frequencies it tends to 1."
    },
    {
        "anchor": "Mediated interactions and photon bound states in an exciton-polariton\n  mixture: The quest to realise strongly interacting photons remains an outstanding\nchallenge both for fundamental science and for applications. Here, we explore\nmediated photon-photon interactions in a highly imbalanced two-component\nmixture of exciton-polaritons in a semiconductor microcavity. Using a theory\nthat takes into account non-perturbative correlations between the excitons as\nwell as strong light-matter coupling, we demonstrate the high tunability of an\neffective interaction between quasiparticles formed by minority component\npolaritons interacting with a Bose-Einstein condensate (BEC) of a majority\ncomponent polaritons. In particular, the interaction, which is mediated by the\nexchange of sound modes in the BEC can be made strong enough to support a bound\nstate of two quasiparticles. Since these quasiparticles consist partly of\nphotons, this in turn corresponds to a dimer state of photons propagating\nthrough the BEC. This gives rise to a new light transmission line where the\nbound state wave function is directly mapped onto correlations between outgoing\nphotons. Our findings open up new routes for realising highly non-linear\noptical materials and novel hybrid light-matter quantum systems.",
        "positive": "Effective field analysis using the full angular spin-orbit torque\n  magnetometry dependence: Spin-orbit torques promise ultra-efficient magnetization switching used for\nadvanced devices based on emergent quasi-particles such as domain walls and\nskyrmions. Recently, the spin structure dynamics, materials and systems with\ntailored spin-orbit torques are being developed. A method, which allows one to\ndetect the acting torques in a given system as a function of the magnetization\ndirection is the torque-magnetometry method based on a higher harmonics\nanalysis of the anomalous Hall-effect. Here we show that the effective fields\nacting on magnetic domain walls that govern the efficiency of their dynamics\nrequire a sophisticated analysis taking into account the full angular\ndependence of the torques. Using a 1-D model we compared the spin orbit torque\nefficiencies by depinning measurements and spin torque magnetometry. We show\nthat the effective fields can be accurately determined and we find good\nagreement. Thus our method allows us now to rapidly screen materials and\npredict the resulting quasi-particle dynamics."
    },
    {
        "anchor": "Moir\u00e9 Engineering and Topological Flat Bands in Twisted Orbital-Active\n  Bilayers: Topological flat bands at the Fermi level offer a promising platform to study\na variety of intriguing correlated phase of matter. Here we present band\nengineering in the twisted orbital-active bilayers with spin-orbit coupling.\nThe symmetry constraints on the interlayer coupling that determines the\neffective potential for low-energy physics of moir\\'e electrons are\nexhaustively derived for two-dimensional point groups. We find the line graph\nor biparticle sublattice of moir\\'e pattern emerge with a minimal $C_3$\nsymmetry, which exhibit isolated electronic flat bands with nontrivial\ntopology. The band flatness is insensitive to the twist angle since they come\nfrom the interference effect. Armed with this guiding principle, we predict\nthat twisted bilayers of 2H-PbS$_2$ and CdS realize the salient physics to\nengineer two-dimensional topological quantum phases. At small twist angles,\nPbS$_2$ heterostructures give rise to an emergent moir\\'e Kagom\\'e lattice,\nwhile CdS heterostructures lead to an emergent moir\\'e honeycomb lattice, and\nboth of them host moir\\'e quantum spin Hall insulators with almost flat\ntopological bands. We further study superconductivity of these two systems with\nlocal attractive interactions. The superfluid weight and\nBerezinskii-Kosterlitz-Thouless temperature are determined by multiband\nprocesses and quantum geometry of the band in the flat-band limit when the\npairing potential exceeds the band width. Our results demonstrate twisted\nbilayers with multi-orbitals as a promising tunable platform to realize\ncorrelated topological phases.",
        "positive": "Vacancy tuned thermoelectric properties and high spin filtering\n  performance in graphene/silicene heterostructures: The main contribution of this paper is to study the spin caloritronic effects\nin defected graphene/silicene nanoribbon (GSNR) junctions. Each step-like GSNR\nis subjected to the ferromagnetic exchange and local external electric fields,\nand their responses are determined using the nonequilibrium Greens function\n(NEGF) approach. To further study the thermoelectric (TE) properties of the\nGSNRs, three defect arrangements of divacancies (DVs) are also considered for a\nlarger system, and their responses are re-evaluated. The results demonstrate\nthat the defected GSNRs with the DVs can provide an almost perfect thermal spin\nfiltering effect (SFE), and spin switching. A negative differential\nthermoelectric resistance (NDTR) effect and high spin polarization efficiency\n(SPE) larger than 99.99 percent are obtained. The system with the DV defects\ncan show a large spin-dependent Seebeck coefficient, equal to 1.2 mV/K, which\nis relatively large and acceptable. Appropriate thermal and electronic\nproperties of the GSNRs can also be obtained by tuning up the DV orientation in\nthe device region. Accordingly, the step-like GSNRs can be employed to produce\nhigh efficiency spin caloritronic devices with various features in practical\napplications."
    },
    {
        "anchor": "Sublattice asymmetry of impurity doping in graphene: A review: In this review we highlight recent theoretical and experimental work on\nsublattice asymmetric doping of impurities in graphene, with a focus on\nsubstitutional Nitrogen dopants. It is well known that one current limitation\nof graphene in regards to its use in electronics is that in its ordinary state\nit exhibits no band gap. By doping one of its two sublattices preferentially it\nis possible to not only open such a gap, which can furthermore be tuned through\ncontrol of the dopant concentration, but in theory produce quasi-ballistic\ntransport of electrons in the undoped sublattice, both important qualities for\nany graphene device to be used competetively in future technology. We outline\ncurrent experimental techniques for synthesis of such graphene monolayers and\ndetail theoretical efforts to explain the mechanisms responsible for the\neffect, before suggesting future research directions in this nascent field.",
        "positive": "Slave-boson Keldysh field theory for the Kondo effect in quantum dots: We present a {\\it nonequilibrium nonperturbative} field theory for the Kondo\neffect in strongly interacting quantum dots at finite temperatures. Unifying\nthe slave-boson representation with the Keldysh field integral an effective\nKeldysh action is derived and explored in the vicinity of the zero\nslave-bosonic field configuration. The theory properly reflects the essential\nfeatures of the Kondo physics and at the same time significantly simplifies a\nfield-theoretic treatment of the phenomenon, avoiding complicated saddle point\nanalysis or 1/N expansions, used so far. Importantly, our theory admits a {\\it\nclosed analytical} solution which explains the mechanism of the Kondo effect in\nterms of an interplay between the real and imaginary parts of the slave-bosonic\nself-energy. It thus provides a convenient nonperturbative building block,\nplaying the role of a \"free propagator\", for more advanced theories. We finally\ndemonstrate that already this simplest possible field theory is able to\ncorrectly reproduce experimental data on the Kondo peak observed in the\ndifferential conductance, correctly predicts the Kondo temperature and, within\nits applicability range, has the same universal temperature dependence of the\nconductance as the one obtained in numerical renormalization group\ncalculations."
    },
    {
        "anchor": "Spin Effects and Transport in Quantum Dots with overlapping Resonances: The role of spin is investigated in the transport through a quantum dot with\ntwo overlapping resonances (one having a width larger than the level separation\nand the other very narrow, cf. Silvestrov and Imry, Phys. Rev. Lett. {\\bf 85},\n2565 (2000)). For a series of consecutive charging resonances, one electron\nfrom the leads populates one and the same broad level in the dot. Moreover,\nthere is the tendency to occupy the same level also by the second electron\nwithin the same resonance. This second electron is taken from the narrow levels\nin the dot. The narrow levels are populated (and broad level is depopulated)\nvia sharp rearrangements of the electronic configuration in the Coulomb\nblockade valleys. Possible experimental manifestations of this scenario are\nconsidered. Among these there are sharp features in the valleys and in the\nMixed Valence regime and an unusual Kondo effect.",
        "positive": "Planar massless fermions in Coulomb and Aharonov-Bohm potentials: Solutions to the Dirac equation are constructed for a massless charged\nfermion in Coulomb and Aharonov--Bohm potentials in 2+1 dimensions. The Dirac\nHamiltonian on this background is singular and needs a one-parameter\nself-adjoint extension, which can be given in terms of self-adjoint boundary\nconditions. We show that the virtual (quasistationary) bound states emerge in\nthe presence of an attractive Coulomb potential when the so-called effective\ncharges become overcritical and discuss a restructuring of the vacuum of the\nquantum electrodynamics when the virtual bound states emerge. We derive\nequations, which determine the energies and lifetimes of virtual bound states,\nfind solutions of obtained equations for some values of parameters as well as\nanalyze the local density of states as a function of energy in the presence of\nCoulomb and Aharonov--Bohm potentials."
    },
    {
        "anchor": "Interaction-induced beats of Friedel oscillations in quantum wires: We analyze the spectrum of electron density oscillations in an interacting\none-dimensional electron system with an impurity. The system's inhomogeneity is\ncharacterized by different values of Fermi wave vectors $k_F=k_{L/R}$ on\nleft/right side of the scatterer, leading to a Landauer dipole formation. We\ndemonstrate, that while in the noninteracting system the Friedel oscillations\npossess only one periodicity related to the local $k_F$, say $k_L$ on the left\nside, the interplay of the interactions and the Landauer dipole generates an\nadditional peak in the spectrum of density oscillations at the counterpart\n$k_R$. Being only present in correlated systems, the position and shape of this\nspectral feature, which in coordinate space is observable as a beating pattern\nin the Friedel oscillations, reveals many important details about the nature of\ninteractions. Thus it has a potential to become an investigation tool in\ncondensed matter physics.",
        "positive": "Bending effects and optical properties of WSe2 nanoribbons of\n  topological phase: A WSe2 monolayer of 1T' phase is a large band gap quantum spin Hall\ninsulator, supporting dissipationless charge and spin transports through the\ntopologically protected edge states. In this work, we explore the nanoribbon\nforms of 1T' phase WSe2 by first-principles density functional calculations and\nthe many-body perturbation GW and Bethe-Salpeter equation method. We found that\nthe 1T' WSe2 nanoribbon can show topological edge states with a ribbon width of\n~4-6 nm. Those edge bands show crossing through the Fermi level an odd number\nof times, with one kind of spin-polarization connecting the valence band\ncontinuum and conduction band continuum. The topological features of the edge\nbands hold even under small and medium bending in the nanoribbon, while large\nbending induces large band splitting, resulting in a topological switch-off in\nthe edge bands. The semiconducting 1T' WSe2 nanoribbon shows a large tunability\nwith bending in optical absorption spectra and exciton states. The\nlowest-energy exciton is changed from optically dark in the flat nanoribbon to\nbright in the bent nanoribbons. These properties in the 1T' WSe2 nanoribbons\nsuggest potential applications in controllable quantum electronics and\nexciton-based quantum information processes."
    },
    {
        "anchor": "Hall Crystal States at $\u03bd=2$ and Moderate Landau Level Mixing: The $\\nu=2$ quantum Hall state at low Zeeman coupling is well-known to be a\ntranslationally invariant singlet if Landau level mixing is small. At zero\nZeeman interaction, as Landau level mixing increases, the translationally\ninvariant state becomes unstable to aninhomogeneous state. This is the first\nrealistic example of a full Hall crystal, which shows the coexistence of\nquantum Hall order and density wave order. The full Hall crystal differs from\nthe more familiar Wigner crystal by a topological property, which results in it\nhaving only linearly dispersing collective modes at small $q$, and no $q^{3/2}$\nmagnetophonon. I present calculations of the topological number and the\ncollective modes.",
        "positive": "Quantum bistability and spin current shot noise of a single quantum dot\n  coupled to an optical microcavity: Here we explore spin dependent quantum transport through a single quantum dot\ncoupled to an optical microcavity. The spin current is generated by electron\ntunneling between a single doped reservoir and the dot combined with intradot\nspin flip transitions induced by a quantized cavity mode. In the limit of\nstrong Coulomb blockade, this model is analogous to the Jaynes-Cummings model\nin quantum optics and generates a pure spin current in the absence of any\ncharge current. Earlier research has shown that in the classical limit where a\nlarge number of such dots interact with the cavity field, the spin current\nexhibits bistability as a function of the laser amplitude that drives the\ncavity. We show that in the limit of a single quantum dot this bistability\ncontinues to be present in the intracavity photon statistics. Signatures of the\nbistable photon statistics manifest themselves in the frequency dependent shot\nnoise of the spin current despite the fact that the quantum mechanical average\nspin current no longer exhibits bistability. Besides having significance for\nfuture quantum dot based optoelectronic devices, our results shed light on the\nrelation between bistability, which is traditionally viewed as a classical\neffect, and quantum mechanics."
    },
    {
        "anchor": "Interface electronic states and boundary conditions for envelope\n  functions: The envelope-function method with generalized boundary conditions is applied\nto the description of localized and resonant interface states. A complete set\nof phenomenological conditions which restrict the form of connection rules for\nenvelope functions is derived using the Hermiticity and symmetry requirements.\nEmpirical coefficients in the connection rules play role of material parameters\nwhich characterize an internal structure of every particular heterointerface.\nAs an illustration we present the derivation of the most general connection\nrules for the one-band effective mass and 4-band Kane models. The conditions\nfor the existence of Tamm-like localized interface states are established. It\nis shown that a nontrivial form of the connection rules can also result in the\nformation of resonant states. The most transparent manifestation of such states\nis the resonant tunneling through a single-barrier heterostructure.",
        "positive": "Coulomb induced positive current-current correlations in normal\n  conductors: In the white-noise limit current correlations measured at different contacts\nof a mesoscopic conductor are negative due to the antisymmetry of the wave\nfunction (Pauli principle). We show that current fluctuations at capacitive\ncontacts induced via the long range Coulomb interaction as consequence of\ncharge fluctuations in the mesoscopic sample can be {\\it positively}\ncorrelated. The positive correlations are a consequence of the extension of the\nwave-functions into areas near both contacts. As an example we investigate in\ndetail a quantum point contact in a high magnetic field under conditions in\nwhich transport is along an edge state."
    },
    {
        "anchor": "Fano effect in a ring-dot system with tunable coupling: Transport measurements are presented on a quantum ring that is tunnel-coupled\nto a quantum dot. When the dot is in the Coulomb blockade regime, but strongly\ncoupled to the open ring, Fano line shapes are observed in the current through\nthe ring, when the electron number in the dot changes by one. The symmetry of\nthe Fano resonances is found to depend on the magnetic flux penetrating the\narea of the ring and on the strength of the ring-dot coupling. At temperatures\nabove T=0.65 K the Fano effect disappears while the Aharonov-Bohm interference\nin the ring persists up to T=4.2 K. Good agreement is found between these\nexperimental observations and a single channel scattering matrix model\nincluding decoherence in the dot.",
        "positive": "A thermally driven out-of-equilibrium two-impurity Kondo system: The archetypal two-impurity Kondo problem in a serially-coupled double\nquantum dot is investigated in the presence of a thermal bias $\\theta$. The\nslave-boson formulation is employed to obtain the nonlinear thermal and\nthermoelectrical responses. When the Kondo correlations prevail over the\nantiferromagnetic coupling $J$ between dot spins we demonstrate that the setup\nshows negative differential thermal conductance regions behaving as a thermal\ndiode. Besides, we report a sign reversal of the thermoelectric current\n$I(\\theta)$ controlled by $t/\\Gamma$ ($t$ and $\\Gamma$ denote the interdot\ntunnel and reservoir-dot tunnel couplings, respectively) and $\\theta$. All\nthese features are attributed to the fact that at large $\\theta$, both\n$Q(\\theta)$ (heat current) and $I(\\theta)$ are suppressed regardless the value\nof $t/\\Gamma$ because the double dot decouples at high thermal biases.\nEventually, and for a finite $J$, we investigate how the\nKondo-to-antiferromagnetic crossover is altered by $\\theta$."
    },
    {
        "anchor": "S-Matrix Poles Close to Thresholds in Confined Geometries: We have studied the behavior of the S-matrix poles near threshold for quantum\nwaveguides coupled to a cavity with a defect. We emphasize the occurrence of\nboth dominant and shadow poles on the various sheets of the energy Riemann\nsurface, and show that the changes of the total conductivity near threshold as\nthe cavity's width changes can be explained in terms of dominant to shadow pole\ntransitions.",
        "positive": "Strain-induced pseudomagnetic field and Landau levels in photonic\n  structures: Magnetic effects at optical frequencies are notoriously weak. This is\nevidenced by the fact that the magnetic permeability of nearly all materials is\nunity in the optical frequency range, and that magneto-optical devices (such as\nFaraday isolators) must be large in order to allow for a sufficiently strong\neffect. In graphene, however, it has been shown that inhomogeneous strains can\ninduce 'pseudomagnetic fields' that behave very similarly to real fields. Here,\nwe show experimentally and theoretically that, by properly structuring a\ndielectric lattice, it is possible to induce a pseudomagnetic field at optical\nfrequencies in a photonic lattice, where the propagation dynamics is equivalent\nto the evolution of an electronic wavepacket in graphene. To our knowledge,\nthis is the first realization of a pseudomagnetic field in optics. The induced\nfield gives rise to multiple photonic Landau levels (singularities in the\ndensity of states) separated by band gaps. We show experimentally and\nnumerically that the gaps between these Landau levels give rise to transverse\nconfinement of the optical modes. The use of strain allows for the exploration\nof magnetic effects in a non-resonant way that would be otherwise inaccessible\nin optics. Employing inhomogeneous strain to induce pseudomagnetism suggests\nthe possibility that aperiodic photonic crystal structures can achieve greater\nfield-enhancement and slow-light effects than periodic structures via the high\ndensity-of-states at Landau levels. Generalizing these concepts to other\nsystems beyond optics, for example with matter waves in optical potentials,\noffers new intriguing physics that is fundamentally different from that in\npurely periodic structures."
    },
    {
        "anchor": "Basins of attraction of a nonlinear nanomechanical resonator: We present an experiment that systematically probes the basins of attraction\nof two fixed points of a nonlinear nanomechanical resonator and maps them out\nwith high resolution. We observe a separatrix which progressively alters shape\nfor varying drive strength and changes the relative areas of the two basins of\nattraction. The observed separatrix is blurred due to ambient fluctuations,\nincluding residual noise in the drive system, which cause uncertainty in the\npreparation of an initial state close to the separatrix. We find a good\nagreement between the experimentally mapped and theoretically calculated basins\nof attraction.",
        "positive": "Spin wave excitation and directional propagation in presence of magnetic\n  charges in square artificial spin ice: Artificial spin ice is a special class of engineered lattice of highly shape\nanisotropic single domain magnetic nanostructures which is used as one of the\nmodel systems to study the spin ice behavior observed in pyrochlore oxides. The\nnanomagnets interact via dipolar interaction which results in correlated\nmagnetization dynamics exhibiting macroscopic spin configuration states. Here,\nwe exploit the interplay of underlying magnetic state and external bias field\norientation to study controlled spin wave propagation in square Artificial Spin\nIce (sASI) by performing detailed micromagnetic simulations. We report that\ncareful selection of vertices with local magnetic charges can effectively\ndirect the anisotropic spin wave in presence of an external field. Further, we\nexplore the influence of local charges due to the excited state in\neven-coordinated vertices as well as uncompensated charges due to\nodd-coordinated vertices on spin wave behavior. Our studies suggest that there\nis no perceptible difference on spin wave dynamical behavior due to the origin\nof local magnetic charge in sASI. Our results of controlled and directional\nspin wave propagation in sASI system may be useful for low-power consumption\nbased all magnonic on-chip devices."
    },
    {
        "anchor": "Tailoring the structural and electronic properties of graphene-like ZnS\n  monolayer using biaxial strain: Our First-principles Full-Potential Density Functional Theory (DFT)\ncalculations show that a monolayer of ZnS (ML-ZnS), which is predicted to adopt\na graphene-like planar honeycomb structure with a direct band gap, undergoes\nstrain-induced modifications in its structure and band gap when subjected to\nin-plane homogeneous biaxial strain ($\\delta$). ML-ZnS gets buckled for\ncompressive strain greater than 0.92%; the buckling parameter $\\Delta$ (= 0.00\n\\AA\\, for planar ML-ZnS) linearly increases with increasing compressive strain\n($\\Delta = 0.435$ \\AA \\,at $\\delta = - 5.25$%). A tensile strain of 2.91% turns\nthe direct band gap of ML-ZnS into indirect. Within our considered strain\nvalues of $|\\delta| < 6%$, the band gap shows linearly decreasing (non-linearly\nincreasing as well as decreasing) variation with tensile (compressive) strain.\nThese predictions may be exploited in future for potential applications in\nstrain sensors and other nano-devices such as the nano-electromechanical\nsystems (NEMS).",
        "positive": "Scaling in Plateau-to-Plateau Transition: A Direct Connection of Quantum\n  Hall Systems with Anderson Localization Model: The quantum Hall plateau transition was studied at temperatures down to 1 mK\nin a random alloy disordered high mobility two-dimensional electron gas. A\nperfect power-law scaling with \\kappa=0.42 was observed from 1.2K down to 12mK.\nThis perfect scaling terminates sharply at a saturation temperature of\nT_s~10mK. The saturation is identified as a finite-size effect when the quantum\nphase coherence length (L_{\\phi} ~ T^{-p/2}) reaches the sample size (W) of\nmillimeter scale. From a size dependent study, T_s \\propto W^{-1} was observed\nand p=2 was obtained. The exponent of the localization length, determined\ndirectly from the measured \\kappa and p, is \\nu=2.38, and the dynamic critical\nexponent z = 1."
    },
    {
        "anchor": "Dirac Cone Metric and the Origin of the Spin Connections in Monolayer\n  Graphene: We show that the modulation of the hopping amplitudes in the honeycomb\nlattice of the monolayer graphene uniquely defines a metric which corresponds\nto the shape of the Dirac cone. The spin connection of this effective metric\nfield can be obtained from the microscopic tight-binding Hamiltonian exactly,\ncompleting the analogy between the sublattice pseudospin travelling in the\nmonolayer graphene with ripples and strain fields, and the real spin $1/2$\nfermion travelling in a curved space. The effective metric as seen by the\nsublattice pseudospin is different from the real space metric as defined by the\ntwo-dimensional manifold of the graphene monolayer. All relevant terms of the\neffective gauge field from the microscopic model is calculated exactly for a\nunimodular effective metric.",
        "positive": "Bound states of a two-dimensional electron gas in inhomogeneous magnetic\n  fields: We study the bound states of a two dimensional free electron gas (2DEG)\nsubjected to a perpendicular inhomogeneous magnetic field. An analytical\ntransfer matrix (ATM) based exact quantization formula is derived for magnetic\nfields that vary (arbitrarily) along one spatial direction. As illustrative\nexamples, we consider (1) a class of symmetric power law magnetic fields\nconfined within a strip, followed by the problem of a (2) 2DEG placed under a\nthin ferromagnetic film, which are hitherto unexplored. The exact Landau levels\nfor either cases are obtained. Also, the role of the fringing magnetic field\n(present in the second example) on these levels is discussed."
    },
    {
        "anchor": "Germanium-based quantum emitters for time-reordering entanglement scheme\n  with degenerate exciton and biexciton states: We address the photoluminescence emission of individual germanium extrinsic\ncenters in Al_0.3Ga0.7As epilayers grown on germanium substrates. Through a\nthorough analysis of micro-photoluminescence experiments we demonstrate the\ncapability of high temperature emission (70 K) and multiexcitonic features\n(neutral exciton X, biexciton XX, positive X+ and negative X- charged exciton)\nof these quantum emitters. Finally, we investigate the renormalization of each\nenergy level showing a large and systematic change of the binding energy of XX\nand X+ from positive to negative values (from ~+5 meV up to ~-7 meV covering\nabout ~ 70 meV of the emission energy) with increasing quantum confinement.\nThese light emitters exhibiting energy-degenerate X and XX energy levels at\n~1.855 eV (680 nm) are a promising resource for the generation of entangled\nphotons in the time-reordering scheme on a silicon platform.",
        "positive": "Photon-Induced Magnetization Changes in Single-Molecule Magnets: Microwave radiation applied to single-molecule magnets can induce large\nmagnetization changes when the radiation is resonant with transitions between\nspin levels. These changes are interpreted as due to resonant heating of the\nsample by the microwaves. Pulsed-radiation studies show that the magnetization\ncontinues to decrease after the radiation has been turned off with a rate that\nis consistent with the spin's characteristic relaxation rate. The measured rate\nincreases with pulse duration and microwave power, indicating that greater\nabsorbed radiation energy results in a higher sample temperature. We also\nperformed numerical simulations that qualitatively reproduce many of the\nexperimental results. Our results indicate that experiments aimed at measuring\nthe magnetization dynamics between two levels resonant with the radiation must\nbe done much faster than the >20-microsecond time scales probed in these\nexperiments."
    },
    {
        "anchor": "Relativistic Correction of the Field Emission Current in the\n  Fowler-Nordheim Formalism: As the title implies the article describes the possibility of taking into\naccount the relativistic correction to the field current density of the field\nemission of electrons from the metal. The article provides the reader with some\nanalytic generalization of the Fowler-Nordheim equation with the relativistic\ncorrection. The relativistic correction to the Fowler-Nordheim equation makes\nit possible to take into account the influence of the relativism on the field\nemission current. It is especially noted that the consideration of this\ncorrection is necessary in the case of sufficiently strong electric fields and\nrelatively large interelectrode distances. It should be stressed that this\ncorrection is valid for fixed interelectrode distances that decrease with\nincreasing electric field strength. It means that for the electric field\nstrength of 0.1 to 1 GV/m the interelectrode distance should not exceed values\nof 1 to 0.1 cm. First in the article it is spoken in detail about finding of\nthe electron wave function. Next the field emission current calculations are\ngiven. As a result the transmission coefficient of the potential step from the\nKlein-Gordon equation within the framework of the Fowler-Nordheim approximation\nis found. It is shown that in the case of the interelectrode distance less than\n1 cm, an analytical expression for the field electron emission current density\nis obtained. The conclusion that usually relativistic correction does not\nexceed a tenth of a percent is made. But in the case of the field electron\nemission from pulsars (where the work function and electric field strength are\nmuch higher) the contribution of the relativistic correction about 10 % has\nbeen established.",
        "positive": "Tunable Spin Qubit Coupling Mediated by a Multi-Electron Quantum Dot: We present an approach for entangling electron spin qubits localized on\nspatially separated impurity atoms or quantum dots via a multi-electron,\ntwo-level quantum dot. The effective exchange interaction mediated by the dot\ncan be understood as the simplest manifestation of\nRuderman-Kittel-Kasuya-Yosida exchange, and can be manipulated through gate\nvoltage control of level splittings and tunneling amplitudes within the system.\nThis provides both a high degree of tuneability and a means for realizing\nhigh-fidelity two-qubit gates between spatially separated spins, yielding an\nexperimentally accessible method of coupling donor electron spins in silicon\nvia a hybrid impurity-dot system."
    },
    {
        "anchor": "Ab initio quantum transport through armchair graphene nanoribbons:\n  Streamlines in the current density: We calculate the local current density in pristine armchair graphene\nnanoribbons (AGNRs) with varying width, $N_\\mathrm{C}$, employing a\ndensity-functional-theory-based ab initio transport formalism. We observe very\npronounced current patterns (streamlines) with threefold periodicity in\n$N_\\mathrm{C}$. They arise as a consequence of quantum confinement in the\ntransverse flow direction. Neighboring streamlines are separated by stripes of\nalmost vanishing flow. As a consequence, the response of the current to\nfunctionalizing adsorbates is very sensitive to their placement: adsorbates\nlocated within the current filaments lead to strong backscattering, while\nadsorbates placed in other regions have almost no impact at all.",
        "positive": "Intervalley Scattering of Interlayer Excitons in a\n  MoS$_2$/MoSe$_2$/MoS$_2$ Heterostructure in High Magnetic Field: Degenerate extrema in the energy dispersion of charge carriers in solids,\nalso referred to as valleys, can be regarded as a binary quantum degree of\nfreedom, which can potentially be used to implement valleytronic concepts in\nvan der Waals heterostructures based on transition metal dichalcogenides. Using\nmagneto-photoluminescence spectroscopy, we achieve a deeper insight into the\nvalley polarization and depolarization mechanisms of interlayer excitons formed\nacross a MoS$_2$/MoSe$_2$/MoS$_2$ heterostructure. We account for the\nnon-trivial behavior of the valley polarization as a function of the magnetic\nfield by considering the interplay between exchange interaction and phonon\nmediated intervalley scattering in a system consisting of Zeeman-split energy\nlevels. Our results represent a crucial step towards the understanding of the\nproperties of interlayer excitons, with strong implications for the\nimplementation of atomically thin valleytronic devices."
    },
    {
        "anchor": "Quantum pumping in graphene: We show that graphene-based quantum pumps can tap into evanescent modes,\nwhich penetrate deeply into the device as a consequence of Klein tunneling. The\nevanescent modes dominate pumping at the Dirac point, and give rise to a\nuniversal response under weak driving for short and wide pumps, in close\nanalogy to their role for the minimal conductivity in ballistic transport. In\ncontrast, evanescent modes contribute negligibly to normal pumps. Our findings\nadd a new incentive for the exploration of graphene-based nanoelectronic\ndevices.",
        "positive": "Fractional flux periodicity of a twisted planar square lattice: We present fractional flux periodicity in the ground state of planar systems\nmade of a square lattice whose boundary is compacted into a torus. The\nground-state energy shows a fractional period of the fundamental unit of\nmagnetic flux depending on the twist around the torus axis."
    },
    {
        "anchor": "Stacking-Configuration-Preserved Graphene Quantum Dots Electrochemically\n  Obtained from CVD Graphene: The layer stacking morphology in nanocarbons is paramount for achieving new\nproperties and outperforming applications. Here, we demonstrate that graphene\nquantum dots (GQDs) retain crystallinity and a stacking structure from CVD\ngraphene grown on Ni foam. Our results reveal that GQD subdomains comprise a\nfew-layer graphene structure in the AB -- AB and ABC -- ABC stacking\nconfiguration. HR-TEM images along with a multiple-approach characterization\n(XRD, XPS, UV-vis, AFM, and ATR-IR) exhibit 3.0 to 8.0 nm crystalline GQDs with\n2-6 graphene layers thick indicating a disk-shape structure. The UV-vis\nprofiles show changes in color of the dispersion (from colorless to red) during\nand after the electrochemistry, suggesting a systematic electrooxidation of\ngraphene into smaller, highly crystalline, and more complex sp2/sp3 structures.\nImportantly, a control experiment performed under the same conditions but with\na graphitic rod exhibited large, polydisperse, and multilayer carbon\nstructures. This work demonstrates a relatively easy electrochemical synthesis\nto obtain GQDs which retain the pristine and, in turn, distinctive structure of\ngraphene grown on Ni foam.",
        "positive": "Direction-Dependent Stability of skyrmion lattice in helimagnets induced\n  by Exchange Anisotropy: Exchange anisotropy provides a direction dependent mechanism for the\nstability of the skyrmion lattice phase in noncentrosymmetric bulk chiral\nmagnets. Based on the Fourier representation of the skyrmion lattice, we\nexplain the direction dependence of the temperature-magnetic field phase\ndiagram for bulk MnSi through a phenomenological mean-field model incorporating\nexchange anisotropy. Through quantitative comparison with experimental results,\nwe clarify that the stability of the skyrmion lattice phase in bulk MnSi is\ndetermined by a combined effect of negative exchange anisotropy and thermal\nfluctuation. The effect of exchange anisotropy and the order of Fourier\nrepresentation on the equilibrium properties of the skyrmion lattice is\ndiscussed in detail."
    },
    {
        "anchor": "Current-induced enhancement of photo-response in graphene THz radiation\n  detectors: Thermoelectric readout in a graphene THz radiation detector requires a p-n\njunction across the graphene channel. Even without an intentional p-n junction,\ntwo latent junctions can exist in the vicinity of the electrodes/antennas\nthrough the proximity to metal. In a symmetrical structure, these junctions are\nconnected back-to-back and therefore counterbalance each other with regard to\nrectification of the ac signal. Because of the Peltier effect, a small dc\ncurrent results in additional heating in one- and cooling in another p-n\njunction, thereby breaking the symmetry. The p-n junctions then no longer\ncancel, resulting in a greatly enhanced rectified signal. This allows to\nsimplify the design and effectively control the sensitivity of the\nTHz-radiation detectors.",
        "positive": "Binding energies of excitonic complexes in type-II quantum rings from\n  diffusion quantum Monte Carlo calculations: Excitonic complexes in type-II quantum-ring heterostructures may be\nconsidered as artificial atoms due to the confinement of only one\ncharge-carrier type in an artificial nucleus. Binding energies of excitons,\ntrions, and biexcitons in these nanostructures are then effectively ionization\nenergies of these artificial atoms. The binding energies reported here are\ncalculated within the effective-mass approximation using the diffusion quantum\nMonte Carlo method and realistic geometries for gallium antimonide rings in\ngallium arsenide. The electrons form a halo outside the ring, with very little\ncharge density inside the central cavity of the ring. The de-excitonization and\nbinding energies of the complexes are relatively independent of the precise\nshape of the ring."
    },
    {
        "anchor": "DC current generation by dielectric loss in ferroelectrics: We study dc current generation induced by microwave irradiation to\nferroelectric materials. The dc current generation originates from microwave\nabsorption called dielectric loss due to the delay of dielectric response. Such\ncurrent generation can be formulated as the low-frequency limit of the phonon\nshift current which arises from an increase of electric polarization\naccompanying photoexcitation of phonons due to the electron-phonon coupling. To\nstudy the dc current generation by the dielectric loss, we apply the\ndiagrammatic treatment of nonlinear optical responses to photoexcitations of\nphonons and derive the general formula for phonon shift current. We then study\nthe dc current generation in the low-frequency region and find that the dc\ncurrent scales as $\\propto w^2$ for the linearly polarized light and time\nreversal symmetric systems. We estimate the order of magnitude of the dc\ncurrent generation by dielectric loss, indicating its feasibility for\nexperimental detection in the GHz region.",
        "positive": "Edge spin accumulation: spin Hall effect without bulk spin current: Spin accumulation in a 2D electron gas with Rashba spin-orbit interaction\nsubject to an electric field can take place without bulk spin currents (edge\nspin Hall effect). This is demonstrated for the collisional regime using the\nnon-equilibrium distribution function determined from the standard Boltzmann\nequation. Spin accumulation originates from interference of incident and\nreflected electron waves at the sample boundary."
    },
    {
        "anchor": "Magnetic Field Control of the Optical Spin Hall Effect: We investigate theoretically the effect of an external magnetic field on\npolarization patterns appearing in quantum microcavities due to the optical\nspin Hall effect (OSHE). We show that increase of the magnetic field\nperpendicular to the plane of the cavity resulting in the increase of the\nZeeman splitting leads to the transition from azimuthal separation of\npolarizations to their radial separation. This effect can be straightforwardly\ndetected experimentally.",
        "positive": "The influence of tunneling matrix elements modification due to on-site\n  Coulomb interaction on local tunneling conductivity: Interplay between changes of energy levels and tunneling amplitudes caused by\nlocalized electrons on-site Coulomb interaction depending on non-equilibrium\nelectron filling numbers is analyzed. Specific features of local tunneling\nconductivity spectra for different positions of localized states energy\nrelative to the Fermi level have been investigated by means of self-consistent\nmean field approximation in the presence of non-equilibrium effects. The\nconditions when modifications of tunneling transfer amplitude due to changes of\nelectron filling numbers in the presence of on-site Coulomb interaction should\nbe taken into account in tunneling conductivity spectra have been revealed."
    },
    {
        "anchor": "Ultrafast Field-driven Valley Polarization of Transition Metal\n  Dichalcogenide Quantum Dots: We study theoretically the electron dynamics of transition metal\ndichalcogenide quantum dots in the field of an ultrashort and ultrafast\ncircularly polarized optical pulse. The quantum dots have the shape of a disk\nand their electron systems are described within an effective model with\ninfinite mass boundary conditions. Similar to transition metal dichalcogenide\nmonolayers, a circularly polarized pulse generates ultrafast valley\npolarization of such quantum dots. The dependence of the valley polarization on\nthe size of the dot is sensitive to the dot material and, for different\nmaterials, show both monotonic increase with the dot radius and nonmonotonic\nbehavior with a local maximum at a finite dot radius.",
        "positive": "Strain and the optoelectronic properties of non-planar phosphorene\n  monolayers: Lattice {\\em Kirigami}, ultra-light metamaterials, poly-disperse aggregates,\nceramic nano-lattices, and two-dimensional (2-D) atomic materials share an\ninherent structural discreteness, and their material properties evolve with\ntheir shape. To exemplify the intimate relation among material properties and\nthe local geometry, we explore the properties of phosphorene --a new 2-D atomic\nmaterial-- in a conical structure, and document a decrease of the\nsemiconducting gap that is directly linked to its non-planar shape. This\ngeometrical effect occurs regardless of phosphorene allotrope considered, and\nit provides a unique optical vehicle to single out local structural defects on\nthis 2-D material. We also classify other 2-D atomic materials in terms of\ntheir crystalline unit cells, and propose means to obtain the local geometry\ndirectly from their diverse two-dimensional structures while bypassing common\ndescriptions of shape that are based from a parametric continuum."
    },
    {
        "anchor": "Experimental Determination of a Single Atom Ground State Orbital through\n  Hyperfine Anisotropy: Historically, electron spin resonance (ESR) has provided excellent insight\ninto the electronic, magnetic, and chemical structure of samples hosting spin\ncenters. In particular, the hyperfine interaction between the electron and the\nnuclear spins yields valuable structural information of these centers. In\nrecent years, the combination of ESR and scanning tunneling microscopy\n(ESR-STM) has allowed to acquire such information on individual spin centers of\nmagnetic atoms bound atop a surface, while additionally providing spatial\ninformation about the binding site. Here, we conduct a full angle-dependent\ninvestigation of the hyperfine splitting for individual titanium atoms on\nMgO/Ag(001) by measurements in a vector magnetic field. We observe strong\nanisotropy in both the g-factor and the hyperfine tensor. Combining the results\nof the hyperfine splitting with the symmetry properties of the binding site\nobtained from STM images and a basic point charge model allows us to predict\nthe shape of the electronic ground state configuration of the titanium atom.\nRelying on experimental values only, this method paves the way for a new\nprotocol for electronic structure analysis for spin centers on surfaces.",
        "positive": "Planar Hall effect induced spin rectification effect and its strong\n  impact on spin pumping measurements: Spin pumping is a technique widely used to generate the pure spin current and\ncharacterize the spin-charge conversion in various systems. The reversing sign\nof the symmetric Lorentzian charge current with respect to opposite magnetic\nfield is generally accepted as the key criterion to identify its pure spin\ncurrent origin. However, we herein find that the rectified voltage due to the\nplanar Hall effect can exhibit similar spurious signal, complicating and even\nmisleading the analysis. The distribution of microwave magnetic field and\ninduction current has strong influence on the magnetic field symmetry and\nlineshape of the obtained signal. We further demonstrate a geometry where the\nspin-charge conversion and the rectified voltage can be readily distinguished\nwith a straightforward symmetry analysis."
    },
    {
        "anchor": "On the nature of the negative-conductivity resonance in a superlattice\n  Bloch oscillator: Adding a high-frequency ac component to the bias field of a superlattice\ninduces a synchronous modulation of the velocity with which the electrons\ntraverse the Brillouin zone. In the presence of inelastic scattering, the\nk-space velocity modulation causes a wave-like bunching of the electrons in\nk-space, which in turn introduces a high-frequency component in the real-space\ncurrent, synchronous with the drive field, but phase-shifted relative to the\nlatter. For a drive frequency equal to the Bloch frequency, the phase shift is\nless than 90 degrees (implying a positive ac conductivity), increasing to 90\ndegrees in the limit of a vanishing scattering (a purely reactive current). If\nthe drive frequency is lowered below the Bloch frequency, and the inelastic\nscattering rate remains sufficiently low, the phase shift can increase beyond\n90 degrees, implying a negative ac conductivity, which peaks at a drive\nfrequency not far below the Bloch frequency.",
        "positive": "Kondo effect in a side-coupled double-quantum-dot system embedded in a\n  mesoscopic ring: We study the finite size effect of the Kondo screening cloud in a\ndouble-quantum-dot setup via a large-N slave-boson mean-field theory. In this\nsetup, one of the dots is embedded in a close metallic ring with a finite size\n$L$ and the other dot is side-coupled to the embedded dot via an\nanti-ferromagnetic spin-spin exchange coupling with the strength K. The\nantiferromagnetic coupling favors the local spin-singlet and suppresses the\nKondo screening. The effective Kondo temperature T_k (proptotional to the\ninverse of the Kondo screening cloud size) shows the Kosterlitz--Thouless (KT)\nscaling at finite sizes, indicating the quantum transition of the KT type\nbetween the Kondo screened phase for K < K_c and the local spin-singlet phase\nfor K > K_c in the thermodynamic limit with K_c being the critical value. The\nmean-field phase diagram as a function of 1/L and K shows a crossover between\nKondo and local spin-singlet ground states for K < K_c (L=4n, 4n+1, 4n+3) and\nfor K>K_c (L=4n+2). To look into the crossover region more closely, the local\ndensity of states on the quantum dot and the persistent current at finite sizes\nwith different values of $K$ are also calculated."
    },
    {
        "anchor": "Two-eigenfunction correlation in a multifractal metal and insulator: We consider the correlation of two single-particle probability densities\n$|\\Psi_{E}({\\bf r})|^{2}$ at coinciding points ${\\bf r}$ as a function of the\nenergy separation $\\omega=|E-E'|$ for disordered tight-binding lattice models\n(the Anderson models) and certain random matrix ensembles. We focus on the\nmodels in the parameter range where they are close but not exactly at the\nAnderson localization transition. We show that even far away from the critical\npoint the eigenfunction correlation show the remnant of multifractality which\nis characteristic of the critical states. By a combination of the numerical\nresults on the Anderson model and analytical and numerical results for the\nrelevant random matrix theories we were able to identify the Gaussian random\nmatrix ensembles that describe the multifractal features in the metal and\ninsulator phases. In particular those random matrix ensembles describe new\nphenomena of eigenfunction correlation we discovered from simulations on the\nAnderson model. These are the eigenfunction mutual avoiding at large energy\nseparations and the logarithmic enhancement of eigenfunction correlations at\nsmall energy separations in the two-dimensional (2D) and the three-dimensional\n(3D) Anderson insulator. For both phenomena a simple and general physical\npicture is suggested.",
        "positive": "Signatures of hidden octupolar order from nonlinear Hall effects: Detecting symmetry-breaking hidden orders with conventional probes has been a\nlong-standing challenge in the field of magnetism. Higher-rank multipolar\nordering $-$ anisotropic charge and magnetization distributions arising from a\ncombination of spin-orbit coupling and crystalline environments $-$ is a\nquintessential example of such hidden orders, where new protocols of direct\ndetection remain highly desirable. In this work, we propose non-linear Hall\neffects as a novel probe for multipolar ordering in metallic systems. Taking\ninspiration from the family of Pr-based heavy-fermion compounds,\nPr(Ti,V)$_2$Al$_{20}$, we formulate a minimal cubic-lattice model of conduction\nelectrons coupled to a ferro-octupolar order parameter. The\ntime-reversal-breaking order leads to a band structure that supports strong\nquadrupolar moments of the Berry curvature (BC). Using a semi-classical\nBoltzmann formalism in conjunction with a symmetry analysis, we demonstrate\nthat the BC quadrupoles produce a third harmonic generation of the Hall voltage\n$[V_H(3 \\omega)]$ measurable in an AC Hall experiment. Properties of the Hall\nresponse such as its anisotropy, its dissipationlessness, and its dependence on\nthe order parameter are also examined. Our work encourages a new realm of\ninvestigation of multipolar ordering from non-linear transport experiments."
    },
    {
        "anchor": "Current-induced forces: a simple derivation: We revisit the problem of forces on atoms under current in nanoscale\nconductors. We derive and discuss the five principal kinds of force under\nsteady-state conditions from a simple standpoint that - with the help of\nbackground literature - should be accessible to physics undergraduates. The\ndiscussion aims at combining methodology with an emphasis on the underlying\nphysics through examples. We discuss and compare two forces present only under\ncurrent - the non-conservative electron wind force and a Lorentz-like\nvelocity-dependent force. It is shown that in metallic nanowires both display\nsignificant features at the wire surface, making it a candidate for the\nnucleation of current-driven structural transformations and failure. Finally we\ndiscuss the problem of force noise and the limitations of Ehrenfest dynamics.",
        "positive": "Tunable even- and odd-denominator fractional quantum Hall states in\n  trilayer graphene: The fractional quantum Hall (FQH) states are exotic quantum many-body phases\nwhose elementary charged excitations are neither bosons nor fermions but\nanyons, obeying fractional braiding statistics. While most FQH states are\nbelieved to have Abelian anyons, the Moore-Read type states with even\ndenominators, appearing at half filling of a Landau level (LL), are predicted\nto possess non-Abelian excitations with appealing potentials in topological\nquantum computation. These states, however, depend sensitively on the orbital\ncontents of the single-particle LL wavefunction and the mixing between\ndifferent LLs. Although they have been observed in a few materials, their\nnon-Abelian statistics still awaits experimental confirmation. Here we show\nmagnetotransport measurements on Bernal-stacked trilayer graphene (TLG), whose\nunique multiband structure facilitates the interlaced LL mixing, which can be\ncontrolled by external magnetic and displacement fields. We observe a series of\nrobust FQH states including even-denominator ones at filling factors\n$\\nu=-9/2$, $-3/2$, $3/2$ and $9/2$. In addition, we are able to finetune the\nLL mixing and crossings to drive quantum phase transitions of these\nhalf-filling states and their neighboring odd-denominator ones, exhibiting a\nrelated emerging and waning behavior. Our results establish TLG as a\ncontrollable system for tuning the weights of LL orbitals and mixing strength,\nand a fresh platform to seek for non-Abelian quasi-particles."
    },
    {
        "anchor": "Electrical Stressing Induced Monolayer Vacancy Island Growth on TiSe2: To ensure the practical application of atomically thin transition metal\ndichalcogenides, it is essential to characterize their structural stability\nunder external stimuli such as electric fields and currents. Using vacancy\nmonolayer islands on TiSe2 surfaces as a model system, for the first time we\nhave observed a shape evolution and growth from triangular to hexagonal driven\nby scanning tunneling microscopy (STM) electrical stressing. The size of\nislands shows linear growth with a rate of (3.00 +- 0.05) x 10-3 nm/s, when the\nSTM scanning parameters are held fixed at Vs = 1.0 V and I = 1.8 nA. We further\nquantified how the growth rate is related to the tunneling current magnitude.\nOur simulations of monolayer island evolution using phase-field modeling are in\ngood agreement with our experimental observations, and point towards\npreferential edge atom dissociation under STM scanning driving the observed\ngrowth. The results could be potentially important for device applications of\nultrathin transition metal dichalcogenides and related 2D materials subject to\nelectrical stressing under device operating conditions.",
        "positive": "Non-adiabatic Hall effect at Berry curvature hot spot: Hot spot of Berry curvature is usually found at Bloch band anti-crossings,\nwhere the Hall effect due to the Berry phase can be most pronounced. With small\ngaps there, the adiabatic limit for the existing formulations of Hall current\ncan be exceeded in a moderate electric field. Here we present a theory of\nnon-adiabatic Hall effect, capturing non-perturbatively the across gap\nelectron-hole excitations by the electric field. We find a general connection\nbetween the field induced electron-hole coherence and intrinsic Hall velocity.\nIn coherent evolution, the electron-hole coherence can manifest as a sizeable\nac Hall velocity. When environmental noise is taken into account, its joint\naction with the electric field favors a form of electron-hole coherence that is\nfunction of wavevector and field only, leading to a dc nonlinear Hall effect.\nThe Hall current has all odd order terms in field, and still retains the\nintrinsic role of the Berry curvature. The quantitative demonstration uses the\nexample of gapped Dirac cones, and our theory can be used to describe the bulk\npseudospin Hall current in insulators with gapped edge such as graphene and 2D\nMnBi$_{2}$Te$_{4}$"
    },
    {
        "anchor": "Unstable and stable regimes of polariton condensation: Modulational instabilities play a key role in a wide range of nonlinear\noptical phenomena, leading e.g. to the formation of spatial and temporal\nsolitons, rogue waves and chaotic dynamics. Here we experimentally demonstrate\nthe existence of a modulational instability in condensates of cavity\npolaritons, arising from the strong coupling of cavity photons with quantum\nwell excitons. For this purpose we investigate the spatiotemporal coherence\nproperties of polariton condensates in GaAs-based microcavities under\ncontinuous-wave pumping. The chaotic behavior of the instability results in a\nstrongly reduced spatial and temporal coherence and a significantly\ninhomogeneous density. Additionally we show how the instability can be tamed by\nintroducing a periodic potential so that condensation occurs into negative mass\nstates, leading to largely improved coherence and homogeneity. These results\npave the way to the exploration of long-range order in dissipative quantum\nfluids of light within a controlled platform.",
        "positive": "High quality magnetotransport in graphene using the edge-free Corbino\n  geometry: We report fabrication of graphene devices in a Corbino geometry consisting of\nconcentric circular electrodes with no physical edge connecting the inner and\nouter electrodes. High device mobility is realized using boron nitride\nencapsulation together with a dual-graphite gate structure. Bulk conductance\nmeasurement in the quantum Hall effect (QHE) regime outperforms previously\nreported Hall bar measurements, with improved resolution observed for both the\ninteger and fractional QHE states. We identify apparent phase transitions in\nthe fractional sequence in both the lowest and first excited Landau levels\n(LLs) and observed features consistent with electron solid phases in higher\nLLs."
    },
    {
        "anchor": "Dynamical Shiba states by precessing magnetic moments in an s-wave\n  superconductor: We study theoretically the dynamics of a Shiba state forming around\nprecessing classical spin in an s-wave superconductor. Utilizing a rotating\nwave description for the precessing magnetic impurity, we find the resulting\nShiba bound state quasi-energy and the spatial extension of the Shiba\nwavefunction. We show that such a precession pertains to dc charge and spin\ncurrents flowing through a normal STM tip tunnel coupled to the superconductor\nin the vicinity of the impurity. We calculate these currents and find that they\nstrongly depend on the magnetic impurity precession frequency, precession\nangle, and on the position of the Shiba energy level in the superconducting\ngap. The resulting charge current is found to be proportional to the difference\nbetween the electron and hole wavefunctions of the Shiba state, being a direct\nmeasure for such an asymmetry. By dynamically driving the impurity one can\ninfer the spin dependence of the Shiba states in the absence of a\nspin-polarized STM tip",
        "positive": "Edge-Corner Correspondence: Boundary-Obstructed Topological Phases with\n  Chiral Symmetry: The bulk-edge correspondence characterizes topological insulators and\nsuperconductors. We generalize this concept to the bulk-corner correspondence\nand the edge-corner correspondence in two dimensions. In the bulk-corner\n(edge-corner) correspondence, the topological number is defined for the bulk\n(edge), while the topological phase is evidenced by the emergence of\nzero-energy corner states. It is shown that the boundary-obstructed topological\nphases recently proposed are the edge-corner-correspondence type, while the\nhigher-order topological phases are classified into the\nbulk-corner-correspondence type and the edge-corner-correspondence type. We\nconstruct a simple model exhibiting the edge-corner correspondence based on two\nChern insulators having the $s$-wave, $d$-wave and $s_{\\pm }$-wave pairings. It\nis possible to define topological numbers for the edge Hamiltonians, and we\nhave zero-energy corner states in the topological phase. The emergence of\nzero-energy corner states is observable by measuring the impedance resonance in\ntopological electric circuits."
    },
    {
        "anchor": "Surface charge-transfer doping a quantum-confined silver monolayer\n  beneath epitaxial graphene: Recently the graphene/SiC interface has emerged as a versatile platform for\nthe epitaxy of otherwise unstable, monoelemental, two-dimensional (2D) layers\nvia intercalation. Intrinsically capped into a van der Waals heterostructure\nwith overhead graphene, they compose a new class of quantum materials with\nstriking properties contrasting their parent bulk crystals. Intercalated silver\npresents a prototypical example where 2D quantum confinement and inversion\nsymmetry breaking entail a metal-to-semiconductor transition. However, little\nis known about the associated unoccupied states, and control of the Fermi level\nposition across the bandgap would be desirable. Here, we n-type dope a\ngraphene/2D-Ag/SiC heterostack via in situ potassium deposition and probe its\nband structure by means of synchrotron-based angle-resolved photoelectron\nspectroscopy. While the induced carrier densities on the order of $10^{14}$\ncm$^{-2}$ are not yet sufficient to reach the onset of the silver conduction\nband, the band alignment of graphene changes relative to the rigidly shifting\nAg valence band and substrate core levels. We further demonstrate an ordered\npotassium adlayer ($2\\times 2$ relative to graphene) with free-electron-like\ndispersion, suppressing plasmaron quasiparticles in graphene via enhanced\nmetalization of the heterostack. Our results establish surface charge-transfer\ndoping as an efficient handle to modify band alignment and electronic\nproperties of a van der Waals heterostructure assembled from graphene and a\nnovel type of monolayered quantum material.",
        "positive": "Quantized Berry Phase and Surface States under Reflection Symmetry or\n  Space-Time Inversion Symmetry: As reflection symmetry or space-time inversion symmetry is preserved, with a\nnon-contractible integral loop respecting the symmetry in the Brilliouin zone,\nBerry phase is quantized in proper basis. Topological nodal lines can be\nenclosed in the integral loop and $\\pi$-Berry phase topologically protects the\nnodal lines. In this work, we show that to have quantized Berry phase\nrestricted by the symmetry in any crystal structure, we choose to use the\ncell-periodic convention and define the origin point in the real space at one\nof the reflection (inversion) centers. In addition, $\\pi$-Berry phase is not\nthe sufficient condition leading to the presence of the stable surface states.\nTheir presence crucially depends on the location of the termination and the\ncrystal structure in the unit cell. By using these new conditions we further\nreexamine if stable surface states exist in the known topological nodal line\nmaterials stemming from reflection symmetry or space-time inversion symmetry."
    },
    {
        "anchor": "Andreev levels in a single-channel conductor: We calculate the subgap density of states of a disordered single-channel\nnormal metal connected to a superconductor at one end (NS junction) or at both\nends (SNS junction). The probability distribution of the energy of a bound\nstate (Andreev level) is broadened by disorder. In the SNS case the two-fold\ndegeneracy of the Andreev levels is removed by disorder leading to a splitting\nin addition to the broadening. The distribution of the splitting is given\nprecisely by Wigner's surmise from random-matrix theory. For strong disorder\nthe mean density of states is largely unaffected by the proximity to the\nsuperconductor, because of localization, except in a narrow energy region near\nthe Fermi level, where the density of states is suppressed with a log-normal\ntail.",
        "positive": "Disorder versus two transport lifetimes in a strongly correlated\n  electron liquid: We report on angle-dependent measurements of the sheet resistances and Hall\ncoefficients of electron liquids in SmTiO3/SrTiO3/SmTiO3 quantum well\nstructures, which were grown by molecular beam epitaxy on (001) DyScO3. We\ncompare their transport properties with those of similar structures grown on\nLSAT [(La0.3Sr0.7)(Al0.65Ta0.35)O3]. On DyScO3, planar defects normal to the\nquantum wells lead to a strong in-plane anisotropy in the transport properties.\nThis allows for quantifying the role of defects in transport. In particular, we\ninvestigate differences in the longitudinal and Hall scattering rates, which is\na non-Fermi liquid phenomenon known as lifetime separation. The residuals in\nboth the longitudinal resistance and Hall angle were found to depend on the\nrelative orientations of the transport direction to the planar defects. The\nHall angle exhibited a robust T2 temperature dependence along all directions,\nwhereas no simple power law could describe the temperature dependence of the\nlongitudinal resistances. Remarkably, the degree of the carrier lifetime\nseparation, as manifested in the distinctly different temperature dependences\nand diverging residuals near a critical quantum well thickness, was completely\ninsensitive to disorder. The results allow for a clear distinction between\ndisorder-induced contributions to the transport and intrinsic, non-Fermi liquid\nphenomena, which includes the lifetime separation."
    },
    {
        "anchor": "Resonant electron transmission through a finite quantum spin chain: Electron transport in a finite one dimensional quantum spin chain (with\nferromagnetic exchange) is studied within an $s-d$ exchange Hamiltonian. Spin\ntransfer coefficients strongly depend on the sign of the $s-d$ exchange\nconstant. For a ferromagnetic coupling, they exhibit a novel resonant pattern,\nreflecting the salient features of the combined electron-spin system. Spin-flip\nprocesses are inelastic and feasible at finite voltage or at finite\ntemperature.",
        "positive": "Quantum electrical transport properties of topological insulator Bi2Te3\n  nanowires: We investigate the quantum transport properties of surface electrons on a\ntopological insulator Bi2Te3 nanowire in a magnetotransport study. Although the\nnanowires are synthesized by using a relatively coarse method of\nelectrochemical deposition, clear Aharonov-Bohm oscillations of phases 0 and pi\nare observed, owing to the highly coherent surface electron channel. The\noscillation amplitude exhibits exponential temperature dependence, suggesting\nthat the phase coherence length L_phi is inversely proportional to the\ntemperature, as in quasi-ballistic systems. In addition, a weak\nantilocalization analysis on the surface channel by using a one-dimensional\nlocalization theory, enabled by successful extraction of the surface\ncontribution from the magnetoconductance data, is provided in support of the\ntemperature dependence of L_phi."
    },
    {
        "anchor": "Dynamically corrected gates for an exchange-only qubit: We provide analytical composite pulse sequences that perform dynamical\ndecoupling concurrently with arbitrary rotations for a qubit coded in the spin\nstate of a triple quantum dot. The sequences are designed to respect realistic\nexperimental constraints such as strictly nonnegative couplings. Logical errors\nand leakage errors are simultaneously corrected. A short pulse sequence is\npresented to compensate nuclear noise and a longer sequence is presented to\nsimultaneously compensate nuclear and charge noise. The capability developed in\nthis work provides a clear prescription for combatting the relevant sources of\nnoise that currently hinder exchange-only qubit experiments.",
        "positive": "Tunneling induced dark states and controllable fluorescence spectrum in\n  quantum-dot molecules: We theoretically investigate the spectrum of the fluorescence from triple\nquantum-dot molecules and demonstrate that it is possible to use tunneling to\ninduce dark states. Unlike the atomic system, in quantum-dot molecules we can\nuse tunneling to create the dark states and control fluorescence emission,\nrequiring no coupling lasers. And interesting features such as quenching and\nnarrowing of the fluorescence can be obtained. We also explain the spectrum\nwith the transition properties of the dressed states generated by the coupling\nof the laser and the two tunneling. The quenching of the fluorescence is due to\nthe tunneling induced dark states, while the narrowing of the central peak is\ndue to the slow decay rate of the dressed levels."
    },
    {
        "anchor": "Effect of edge roughness in graphene nanoribbon transistors: The effects of edge irregularity and mixed edge shapes on the characteristics\nof graphene nanoribbon transistors are examined by self-consistent atomistic\nsimulations based on the non-equilibrium Green's function formalism. The\nminimal leakage current increases due to the localized states induced in the\nband gap, and the on-current decreases due to smaller quantum transmission and\nthe self-consistent electrostatic effect in general. Although the ratio between\nthe on-current and minimal leakage current decreases, the transistor still\nswitches even in the presence of edge roughness. The variation between devices,\nhowever, can be large, especially for a short channel length.",
        "positive": "Quantum blockade and loop current induced by a single lattice defect in\n  graphene nanoribbons: We investigate theoretically the electronic transport properties in narrow\ngraphene ribbons with an adatom-induced defect. It is found that the lowest\nconductance step of a metallic graphene nanoribbon may develop a dip even down\nto zero at certain values of the Fermi energy due to the defect. Accompanying\nthe occurrence of the conductance dip, a loop current develops around the\ndefect. We show how the properties of the conductance dip depend on the\nparameters of the defect, such as the relative position and severity of the\ndefect as well as the width and edges of the graphene ribbons. In particular,\nfor metallic armchair-edges graphene nanoribbons, whether the conductance dip\nappears or not, they can be controlled by choosing the position of the single\ndefect."
    },
    {
        "anchor": "Pinned domain wall oscillator as tunable direct current spin wave\n  emitter: Spin waves are perturbations in the relative orientation of magnetic moments\nin a continuous magnetic system, which have been proposed as a new kind of\ninformation carrier for spin-based low power applications. For this purpose, a\nmajor obstacle to overcome is the energy-efficient excitation of coherent short\nwavelength spin waves and alternatives to excitation via the Oersted field of\nan alternating current need to be explored. Here we show, by means of\nmicromagnetic simulations, how, in a perpendicularly magnetized thin strip, a\ndomain wall pinned at a geometrical constriction emits spin waves when forced\nto rotate by the application of a low direct current flowing along the strip.\nSpin waves propagate only in the direction of the electron's flow at the first\nodd harmonic of the domain wall rotation frequency for which propagation is\nallowed. Excitation is due to in-plane dipolar stray field of the rotating\ndomain wall and that the resulting unidirectionality is a consequence of the\ndomain wall displacement at the constriction. On the other hand, the\napplication of an external field opposing domain wall depinning breaks the\nsymmetry for spin wave propagation in the two domains, allowing emission in\nboth directions but at different frequencies. The results presented define a\nnew approach to produce tunable high frequency spin wave emitters of easy\nfabrication and low power consumption.",
        "positive": "Symmetries in the collective excitations of an electron gas in\n  core-shell nanowires: We study the collective excitations and inelastic light scattering\ncross-section of an electron gas confined in a GaAs/AlGaAs coaxial quantum\nwell. These system can be engineered in a core-multi-shell nanowire and inherit\nthe hexagonal symmetry of the underlying nanowire substrate. As a result, the\nelectron gas forms both quasi 1D channels and quasi 2D channels at the quantum\nwell bents and facets, respectively. Calculations are performed within the RPA\nand TDDFT approaches. We derive symmetry arguments which allow to enumerate and\nclassify charge and spin excitations and determine whether excitations may\nsurvive to Landau damping. We also derive inelastic light scattering selection\nrules for different scattering geometries. Computational issues stemming from\nthe need to use a symmetry compliant grid are also investigated systematically."
    },
    {
        "anchor": "Exact solution for square-wave grating covered with graphene: Surface\n  plasmon-polaritons in the THz range: We provide an analytical solution to the problem of scattering of\nelectromagnetic radiation by a square-wave grating with a flat graphene sheet\non top. We show that for deep groves there is a strong plasmonic response with\nlight absorption in the graphene sheet reaching more than 45%, due to the\nexcitation of surface plasmon-polaritons. The case of grating with a graphene\nsheet presenting an induced periodic modulation of the conductivity is also\ndiscussed.",
        "positive": "Negative magneto-resistance of electron gas in a quantum well with\n  parabolic potential: We have studied the electrical conductivity of the electron gas in parallel\nelectric and magnetic fields directed along the plane of a parabolic quantum\nwell (across the profile of the potential). We found a general expression for\nthe electrical conductivity applicable for any magnitudes of the magnetic field\nand the degree of degeneration of the electron gas. A new mechanism of\ngeneration of the negative magnetoresistance has been revealed. It has been\nshown that in a parabolic quantum well with a non-degenerated electron gas the\nnegative magnetoresistance results from spin splitting of the levels of the\nsize quantization."
    },
    {
        "anchor": "First Principles Study of Electronic Structure and Transport in Graphene\n  Grain Boundaries: Grain boundaries play a major role for electron transport in graphene sheets\ngrown by chemical vapor deposition. Here we investigate the electronic\nstructure and transport properties of idealized graphene grain boundaries (GBs)\nin bi-crystals using first principles density functional theory (DFT) and\nnon-equilibrium Greens functions (NEGF). We generated 150 different grain\nboundaries using an automated workflow where their geometry is relaxed with\nDFT. We find that the GBs generally show a quasi-1D bandstructure along the GB.\nWe group the GBs in four classes based on their conductive properties:\ntransparent, opaque, insulating, and spin-polarizing and show how this is\nrelated to angular mismatch, quantum mechanical interference, and out-of-plane\nbuckling. Especially, we find that spin-polarization in the GB correlates with\nout-of-plane buckling. We further investigate the characteristics of these\nclasses in simulated scanning tunnelling spectroscopy and diffusive transport\nalong the GB which demonstrate how current can be guided along the GB.",
        "positive": "Staircase Quantum Dots Configuration in Nanowires for Optimized\n  Thermoelectric Power: The performance of thermoelectric energy harvesters can be improved by\nnanostructures that exploit inelastic transport processes. One prototype is the\nthree-terminal hopping thermoelectric device where electron hopping between\nquantum-dots are driven by hot phonons. Such three-terminal hopping\nthermoelectric devices have potential in achieving high efficiency or power via\ninelastic transport and without relying on heavy-elements or toxic compounds.\nWe show in this work how output power of the device can be optimized via tuning\nthe number and energy configuration of the quantum-dots embedded in parallel\nnanowires. We find that the staircase energy configuration with constant\nenergy-step can improve the power factor over a serial connection of a single\npair of quantum-dots. Moreover, for a fixed energy-step, there is an optimal\nlength for the nanowire. Similarly for a fixed number of quantum-dots there is\nan optimal energy-step for the output power. Our results are important for\nfuture developments of high-performance nanostructured thermoelectric devices."
    },
    {
        "anchor": "Theory of lasing in a two-dimensional array of plasmonic nanolasers: A theory of lasing in a two-dimensional array of metal nanoparticles (MNPs)\ncovered with a thin layer of fluorescent molecules is developed from first\nprinciples. The approach is based on a rigorous account of the local field in a\nclose vicinity of a reflective surface which provides a feedback for molecular\ndipole oscillations. The theory predicts the lasing threshold in such an open\ncavity in terms of the polar angle of laser emission, MNPs shape and the\nmolecular layer thickness. It is demonstrated that the latter parameter plays a\ncrucial role in the lasing condition and controls a switching from conventional\nlasing to lasing without inversion. This research is inspired by recent\nexperiments in this field [N. Toropov et al, Adv. Photonics Res. {\\bf 2},\n2000083 (2021)] and provides the numerical calculations carried out for the\nexperimental conditions.",
        "positive": "Antidot tunneling between Quantum Hall liquids with different filling\n  factors: We consider tunneling through two point contacts between two edges of Quantum\nHall liquids of different filling factors $\\nu_{0,1}=1/ (2m_{0,1}+1)$ with\n$m_0-m_1\\equiv m>0$. Properties of the antidot formed between the point\ncontacts in the strong-tunneling limit are shown to be very different from the\n$\\nu_0 =\\nu_1$ case, and include vanishing average total current in the two\ncontacts and quasiparticles of charge $e/m$. For $m>1$, quasiparticle tunneling\nleads to non-trivial $m$-state dynamics of effective flux through the antidot\nwhich restores the regular ``electron'' periodicity of the current in flux\ndespite the fractional charge and statistics of quasiparticles."
    },
    {
        "anchor": "Homochiral antiferromagnetic merons, antimerons and bimerons realized in\n  synthetic antiferromagnets: The ever-growing demand for device miniaturization and energy efficiency in\ndata storage and computing technology has prompted a shift towards\nantiferromagnetic (AFM) topological spin textures as information carriers,\nowing to their negligible stray fields, leading to possible high device density\nand potentially ultrafast dynamics. We realize, in this work, such chiral\nin-plane (IP) topological antiferromagnetic spin textures, namely merons,\nantimerons, and bimerons in synthetic antiferromagnets by concurrently\nengineering the effective perpendicular magnetic anisotropy, the interlayer\nexchange coupling, and the magnetic compensation ratio. We demonstrate by\nthree-dimensional vector imaging of the N\\'eel order parameter, the topology of\nthose spin textures and reveal globally a well-defined chirality, which is a\ncrucial requirement for controlled current-induced dynamics. Our analysis\nreveals that the interplay between interlayer exchange and interlayer magnetic\ndipolar interactions plays a key role in significantly reducing the critical\nstrength of the Dzyaloshinskii-Moriya interaction required to stabilize\ntopological spin textures, such as AFM merons, making synthetic\nantiferromagnets a promising platform for next-generation spintronics\napplications.",
        "positive": "Comment on \"Universality of the 1/3 shot-noise suppression factor in\n  nondegenerate diffusive conductors\": We argue that the nearly 1/3 suppression of shot noise in nondegenerate\ndiffusive contacts recently obtained by Gonzalez et al. (cond-mat/9803372) is\ndue to the specific choice of the energy-independent elastic scattering time."
    },
    {
        "anchor": "The anomalous Hall effect in ferromagnetic Fe: Skew scattering or side\n  jump?: The question is investigated whether the anomalous Hall effect (AHE) in Fe\nfilms is due to skew scattering or side jump. For this purpose sandwiches of\nFeIn are investigated in which the conduction electrons carry their drift\nvelocity across the interface. This yields an additional AHE conductance\n$\\Delta G_{xy}$ whose dependence on the In mean free path is used to determine\nthe mechanism of the AHE in the Fe film. The structure of the Fe film is kept\nconstant.",
        "positive": "Three-dimensional Modeling of Vacuum Field Emission Nanotriodes: Vacuum nanodevices are devices that the electron transport through them is\nbased on electron field emission from a nano-eimtter to another opposite\nelectrode through a vacuum channel. Geometrically asymmetric metal-vacuum-metal\nstructures were demonstrated to have energy conversion ability for elec-\ntromagnetic waves in the optical range. Combining the ability of these\nstructures to convert optical signals into recti ed current and the ability of\nvacuum nanotriodes to control the eld emission current can allow direct\nprocessing on converted optical signals using a single device. In this paper, a\nthree-dimensional quantum-mechanical method, rather than the approximate\nFowler-Nordheim theory, is used for modeling the eld emission process in\nvertical-type vacuum nanotriodes consisting of an emitter, a collector and a\ngate. The electron transport through the device is computed using a\ntransfer-matrix technique. The potentials of vacuum nanotriodes in the current\nrecti cation and modulation are investigated at low volt- ages. The e ects of\nvarying the structure geometrical parameters on the recti ed current are also\nstudied. The obtained results show that a great enhancement in the recti cation\nproperties is achievable when the gate and the collector are connected through\na DC source. It is also demonstrated that a small variation in the gate voltage\ncan be used either to modulate the recti ed current or to switch the device\ninto a resonant tunneling diode.26"
    },
    {
        "anchor": "Anisotropic exciton transport in transition-metal dichalcogenides: Due to the Coulomb interaction exciton eignestates in monolayer transitional\nmetal dichalcogenides are coherent superposition of two valleys. The exciton\nband which couples to the transverse electric mode of light has parabolic\ndispersion for the center of mass momentum, whereas the one which couples to\nthe transverse magnetic mode has both parabolic and linear components. In this\nwork we present an experimental proposal to observe the signatures of linear\ncomponent of the dispersion. In particular, it is demonstrated that by pumping\nthe system with linearly polarized light the exciton transport is anisotropic\ncompared to circularly polarized pump. We show that the results persist for\nmoderate level of disorder present in realistic systems. Finally, we\ndemonstrate that similar effects can be obtained for positively detuned\nexciton-polaritons, in less stringent experimental requirements compared to\nbare exciton case.",
        "positive": "Enhanced interlayer neutral excitons and trions in trilayer van der\n  Waals heterostructures: Vertically stacked van der Waals heterostructures constitute a promising\nplatform for providing tailored band alignment with enhanced excitonic systems.\nHere we report observations of neutral and charged interlayer excitons in\ntrilayer WSe2-MoSe2-WSe2 van der Waals heterostructures and their dynamics. The\naddition of a WSe2 layer in the trilayer leads to significantly higher\nphotoluminescence quantum yields and tunable spectral resonance compared to its\nbilayer heterostructures at cryogenic temperatures. The observed enhancement in\nthe photoluminescence quantum yield is due to significantly larger\nelectron-hole overlap and higher light absorbance in the trilayer\nheterostructure, supported via first-principle pseudopotential calculations\nbased on spin-polarized density functional theory. We further uncover the\ntemperature- and power-dependence, as well as time-resolved photoluminescence\nof the trilayer heterostructure interlayer neutral excitons and trions. Our\nstudy elucidates the prospects of manipulating light emission from interlayer\nexcitons and designing atomic heterostructures from first-principles for\noptoelectronics."
    },
    {
        "anchor": "Cavity-Enhanced Two-Photon Interference using Remote Quantum Dot Sources: Quantum dots in cavities have been shown to be very bright sources of\nindistinguishable single photons. Yet the quantum interference between two\nbright quantum dot sources, a critical step for photon based quantum\ncomputation, has never been investigated. Here we report on such a measurement,\ntaking advantage of a deterministic fabrication of the devices. We show that\ncavity quantum electrodynamics can efficiently improve the quantum interference\nbetween remote quantum dot sources: poorly indistinguishable photons can still\ninterfere with good contrast with high quality photons emitted by a source in\nthe strong Purcell regime. Our measurements and calculations show that cavity\nquantum electrodynamics is a powerful tool for interconnecting several devices.",
        "positive": "Observation of fractional edge excitations in nanographene spin chains: Fractionalization is a phenomenon in which strong interactions in a quantum\nsystem drive the emergence of excitations with quantum numbers that are absent\nin the building blocks. Outstanding examples are excitations with charge e/3 in\nthe fractional quantum Hall effect, solitons in one-dimensional conducting\npolymers and Majorana states in topological superconductors. Fractionalization\nis also predicted to manifest itself in low-dimensional quantum magnets, such\nas one-dimensional antiferromagnetic S = 1 chains. The fundamental features of\nthis system are gapped excitations in the bulk and, remarkably, S = 1/2 edge\nstates at the chain termini, leading to a four-fold degenerate ground state\nthat reflects the underlying symmetry-protected topological order. Here, we use\non-surface synthesis to fabricate one-dimensional spin chains that contain the\nS = 1 polycyclic aromatic hydrocarbon triangulene as the building block. Using\nscanning tunneling microscopy and spectroscopy at 4.5 K, we probe\nlength-dependent magnetic excitations at the atomic scale in both open-ended\nand cyclic spin chains, and directly observe gapped spin excitations and\nfractional edge states therein. Exact diagonalization calculations provide\nconclusive evidence that the spin chains are described by the S = 1\nbilinear-biquadratic Hamiltonian in the Haldane symmetry-protected topological\nphase. Our results open a bottom-up approach to study strongly correlated\nquantum spin liquid phases in purely organic materials, with the potential for\nthe realization of measurement-based quantum computation."
    },
    {
        "anchor": "Magnetoresistance in the in-plane magnetic field induced semi-metallic\n  phase of inverted HgTe quantum wells: In this study we have measured the magnetoresistance response of inverted\nHgTe quantum wells in the presence of a large parallel magnetic field up to 33\nT is applied. We show that in quantum wells with inverted band structure a\nmonotonically decreasing magnetoresistance is observed when a magnetic field up\nto order 10 T is applied parallel to the quantum well plane. This feature is\naccompanied by a vanishing of non-locality and is consistent with a predicted\nmodification of the energy spectrum that becomes gapless at a critical in-plane\nfield $B_{c}$. Magnetic fields in excess of $B_c$ allow us to investigate the\nevolution of the magnetoresistance in this field-induced semi-metallic region\nbeyond the known regime. After an initial saturation phase in the presumably\ngapless phase, we observe a strong upturn of the longitudinal resistance. A\nsmall residual Hall signal picked up in non-local measurements suggests that\nthis feature is likely a bulk phenomenon and caused by the semi-metallicity of\nthe sample. Theoretical calculations indeed support that the origin of these\nfeatures is classical and a power law upturn of the resistance can be expected\ndue to the specifics of two-carrier transport in thin (semi-)metallic samples\nsubjected to large magnetic fields.",
        "positive": "Negative spin exchange in a multielectron quantum dot: By operating a one-electron quantum dot (fabricated between a multielectron\ndot and a one-electron reference dot) as a spectroscopic probe, we study the\nspin properties of a gate-controlled multielectron GaAs quantum dot at the\ntransition between odd and even occupation number. We observe that the\nmultielectron groundstate transitions from spin-1/2-like to singlet-like to\ntriplet-like as we increase the detuning towards the next higher charge state.\nThe sign reversal in the inferred exchange energy persists at zero magnetic\nfield, and the exchange strength is tunable by gate voltages and in-plane\nmagnetic fields. Complementing spin leakage spectroscopy data, the inspection\nof coherent multielectron spin exchange oscillations provides further evidence\nfor the sign reversal and, inferentially, for the importance of non-trivial\nmultielectron spin exchange correlations."
    },
    {
        "anchor": "Unexpected Electron Transport Suppression in a Heterostructures Graphene\n  MoS2 Multiple Field-Effect Transistor Architecture: We demonstrate a graphene-MoS2 architecture integrating multiple field-effect\ntransistors and we independently probe and correlate the conducting properties\nof van der Waals coupled graphene-MoS2 contacts with the ones of the MoS2\nchannels. Devices are fabricated starting from high-quality single-crystal\nmonolayers grown by chemical vapor deposition and characterized by scanning\nRaman and photoluminescence spectroscopies. Transconductance curves of MoS2 are\ncompared with the current-voltage characteristics of graphene contact stripes,\nrevealing a significant suppression of transport on the n-side of the\ntransconductance curve. Based on ab-initio modeling, the effect is understood\nin terms of trapping by sulfur vacancies, which counter-intuitively depends on\nthe field-effect, even though the graphene contact layer is positioned between\nthe backgate and the MoS2 channel.",
        "positive": "Detection of Tiny Mechanical Motion by Means of the Ratchet Effect: We propose a position detection scheme for a nanoelectromechanical resonator\nbased on the ratchet effect. This scheme has an advantage of being a dc\nmeasurement. We consider a three-junction SQUID where a part of the\nsuperconducting loop can perform mechanical motion. The response of the ratchet\nto a dc current is sensitive to the position of the resonator and the effect\ncan be further enhanced by biasing the SQUID with an ac current. We discuss the\nfeasibility of the proposed scheme in existing experimental setups."
    },
    {
        "anchor": "Role of supercurrents on vortices formation in polariton condensates: Observation of quantized vortices in non-equilibrium polariton condensates\nhas been reported either by spontaneous formation and pinning in the presence\nof disorder or by imprinting them onto the signal or idler of an optical\nparametric oscillator (OPO). Here, we report a detailed analysis of the\ncreation and annihilation of polariton vortex-antivortex pairs in the signal\nstate of a polariton OPO by means of a short optical Gaussian pulse at a\ncertain finite pump wave-vector. A time-resolved, interferometric analysis of\nthe emission allows us to extract the phase of the perturbed condensate and to\nreveal the dynamics of the supercurrents created by the pulsed probe. This flow\nis responsible for the appearance of the topological defects when\ncounter-propagating to the underlying currents of the OPO signal.",
        "positive": "Superconductor-Nanowire Devices from Tunneling to the Multichannel\n  Regime: Zero-Bias Oscillations and Magnetoconductance Crossover: We present transport measurements in superconductor-nanowire devices with a\ngated constriction forming a quantum point contact. Zero-bias features in\ntunneling spectroscopy appear at finite magnetic fields, and oscillate in\namplitude and split away from zero bias as a function of magnetic field and\ngate voltage. A crossover in magnetoconductance is observed: Magnetic fields\nabove ~ 0.5 T enhance conductance in the low-conductance (tunneling) regime but\nsuppress conductance in the high-conductance (multichannel) regime. We consider\nthese results in the context of Majorana zero modes as well as alternatives,\nincluding Kondo effect and analogs of 0.7 structure in a disordered nanowire."
    },
    {
        "anchor": "Spin-transfer in diffusive ferromagnet-normal metal systems with\n  spin-flip scattering: The spin-transfer in biased disordered ferromagnet (F) - normal metal (N)\nsystems is calculated by the diffusion equation. For F1-N2-F2 and\nN1-F1-N2-F2-N3 spin valves, the effect of spin-flip processes in the normal\nmetal and ferromagnet parts are obtained analytically. Spin-flip in the center\nmetal N2 reduces the spin-transfer, whereas spin-flip in the outer normal\nmetals N1 and N3 can increase it by effectively enhancing the spin polarization\nof the device.",
        "positive": "Electrical generation and propagation of spin waves in antiferromagnetic\n  thin films: Electrical generation of THz spin waves is theoretically explored in an\nantiferromangetic nanostrip via the current-induced spin-orbit torque. The\nanalysis based on micromagnetic simulations clearly illustrates that the\nNeel-vector oscillations excited at one end of the magnetic strip can propagate\nin the form of a traveling wave when the nanostrip axis aligns with the\nmagnetic easy-axis. A sizable threshold is observed in the driving current\ndensity or the torque to overcome the unfavorable anisotropy as expected. The\ngenerated spin waves are found to travel over a long distance while the angle\nof rotation undergoes continuous decay in the presence of non-zero damping. The\noscillation frequency is tunable via the strength of the spin-orbit torque,\nreaching the THz regime. Other key characteristics of the spin waves such as\nthe phase and the chirality can also be modulated actively. The simulation\nresults further indicate the possibility of wave-like superposition between the\nexcited spin oscillations, illustrating its application as an efficient source\nof spin-wave signals for information processing."
    },
    {
        "anchor": "Correlations due to localization in quantum eigenfunctions of disordered\n  microwave cavities: Non-universal correlations due to localization are observed in statistical\nproperties of experimental eigenfunctions of quantum chaotic and disordered\nmicrowave cavities. Varying energy {E} and mean free path {l} enable us to\nexperimentally tune from localized to delocalized states. Large level-to-level\nInverse Participation Ratio (IPR I_{2}) fluctuations are observed for the\ndisordered billiards, whose distribution is strongly asymmetric about <I_{2}>.\nThe density auto-correlations of eigenfunctions are shown to decay\nexponentially and the decay lengths are experimentally determined. All the\nresults are quantitatively consistent with calculations based upon nonlinear\nsigma-models.",
        "positive": "Observation of topological edge modes in a quasi-periodic acoustic\n  waveguide: Topological boundary and interface modes are generated in an acoustic\nwaveguide by simple quasi-periodic patternings of the walls. The procedure\nopens many topological gaps in the resonant spectrum and qualitative as well as\nquantitative assessments of their topological character are supplied. In\nparticular, computations of the bulk invariant for the continuum wave equation\nare performed. The experimental measurements reproduce the theoretical\npredictions with high fidelity. In particular, acoustic modes with high\nQ-factors localized in the middle of a breathable waveguide are engineered by a\nsimple patterning of the walls."
    },
    {
        "anchor": "Architecture for high-sensitivity single-shot readout and control of the\n  electron spin of individual donors in silicon: We describe a method to control and detect in single-shot the electron spin\nstate of an individual donor in silicon with greatly enhanced sensitivity. A\nsilicon-based Single-Electron Transistor (SET) allows for spin-dependent\ntunneling of the donor electron directly into the SET island during the\nread-out phase. Simulations show that the charge transfer signals are typically\n\\Delta q > 0.2 e - over an order of magnitude larger than achievable with\nmetallic SETs on the SiO2 surface. A complete spin-based qubit structure is\nobtained by adding a local Electron Spin Resonance line for coherent spin\ncontrol. This architecture is ideally suited to demonstrate and study the\ncoherent properties of donor electron spins, but can be expanded and integrated\nwith classical control electronics in the context of scale-up.",
        "positive": "Transport Properties in Graphene Superlattices: Using Chebyshev polynomials, we study the electronic transport properties of\nmassless Dirac fermions in symmetrical graphene superlattice composed of three\nregions. Matching wavefunctions and using transfer matrix method, we explicitly\ndetermine transmission probability as well as the conductance and Fano factor.\nAt vertical Dirac points, we numerically find that the transmission probability\nshows transmission gaps, conductance has minimums and Fano factor has maximums."
    },
    {
        "anchor": "Bose-Einstein condensate of Dirac magnons: Pumping and collective modes: We explore the formation and collective modes of Bose-Einstein condensate of\nDirac magnons (Dirac BEC). While we focus on two-dimensional Dirac magnons, an\nemployed approach is general and could be used to describe Bose-Einstein\ncondensates with linear quasiparticle spectrum in various systems. By using a\nphenomenological multicomponent model of pumped boson population together with\nbosons residing at Dirac nodes, the formation and time evolution of condensates\nof Dirac bosons is investigated. The condensate coherence and its\nmulticomponent nature are manifested in the Rabi oscillations whose period is\ndetermined by the gap in the spin-wave spectrum. A Dirac nature of the\ncondensates could be also probed by the spectrum of collective modes. It is\nshown that the Haldane gap provides an efficient means to tune between the\ngapped and gapless collective modes as well as controls their stability.",
        "positive": "Disorder-perturbed Landau levels in high electron mobility epitaxial\n  graphene: We show that the Landau levels in epitaxial graphene in presence of localized\ndefects are significantly modified compared to those of an ideal system. We\nreport on magneto-spectroscopy experiments performed on high quality samples.\nBesides typical interband magneto-optical transitions, we clearly observe\nadditional transitions that involve perturbed states associated to short-range\nimpurities such as vacancies. Their intensity is found to decrease with an\nannealing process and a partial self-healing over time is observed.\nCalculations of the perturbed Landau levels by using a delta-like potential\nshow electronic states both between and at the same energies of the Laudau\nlevels of ideal graphene. The calculated absorption spectra involving all\nperturbed and unperturbed states are in very good agreement with the\nexperiments."
    },
    {
        "anchor": "Robust poor man's Majorana zero modes using Yu-Shiba-Rusinov states: The recent realization of a two-site Kitaev chain featuring \"poor man's\nMajorana\" states demonstrates a path forward in the field of topological\nsuperconductivity. Harnessing the potential of these states for quantum\ninformation processing, however, requires increasing their robustness to\nexternal perturbations. Here, we form a two-site Kitaev chain using\nproximitized quantum dots hosting Yu-Shiba-Rusinov states. The strong\nhybridization between such states and the superconductor enables the creation\nof poor man's Majorana states with a gap larger than $70 \\mathrm{~\\mu eV}$. It\nalso greatly reduces the charge dispersion compared to Kitaev chains made with\nnon-proximitized quantum dots. The large gap and reduced sensitivity to charge\nfluctuations will benefit qubit manipulation and demonstration of non-abelian\nphysics using poor man's Majorana states.",
        "positive": "Statistics of Transmission Eigenvalues in Two-Dimensional Quantum\n  Cavities: Ballistic versus Stochastic Scattering: We investigate the statistical distribution of transmission eigenvalues in\nphase-coherent transport through quantum dots. In two-dimensional ab-initio\nsimulations for both clean and disordered two-dimensional cavities, we find\nmarkedly different quantum-to-classical crossover scenarios for these two\ncases. In particular, we observe the emergence of ``noiseless scattering\nstates'' in clean cavities, irrespective of sharp-edged entrance and exit lead\nmouths. We find the onset of these ''classical'' states to be largely\nindependent of the cavity's classical chaoticity, but very sensitive with\nrespect to bulk disorder. Our results suggest that for weakly disordered\ncavities the transmission eigenvalue distribution is determined both by\nscattering at the disorder potential and the cavity walls. To properly account\nfor this intermediate parameter regime we introduce a hybrid crossover scheme\nwhich combines previous models that are valid in the ballisic and the\nstochastic limit, respectively."
    },
    {
        "anchor": "Hexagonally warped exceptional physics in multi-Weyl semimetals: Hexagonal warping (HW) in three-dimensional topological insulators is, by\nnow, well-known. We show that non-Hermitian (NH) loss/gain can generate an\nexceptional HW effect in double Weyl-semimetals (DWSM). This unique feature of\nDWSMs has distinctive effects on Fermi surface topology. Importantly, in the\npresence of such a $k^3$ spin orbit coupling mimicking term, the symmetry\nassociated with the DWSMs is changed, leading to four exceptional points, among\nwhich two are degenerate. Introducing a driving field removes this degeneracy.\nThe combined action of the NH warping and driving parameters leads to notable\neffects, including merging and tuning of exceptional points. We analyze the\ntopological nature of the generated exceptional contours by evaluating several\ntopological invariants, such as winding number, vorticity, and NH Berry\ncurvature. We hope that our theoretical results would initiate possible\nexperiments exploring NH HW effects.",
        "positive": "Spin-orbit interaction in the graphitic nanocone: The Hamiltonian for nanocones with curvature induced spin orbit coupling have\nbeen derived. The effect of curvature induced spin orbit coupling on the\nelectronic properties of graphitic nanocones is considered. Energy spectra for\ndifferent numbers of the pentagonal defects in the tip of the nanocones are\ncalculated. It was shown that the spin orbit interaction considerably affects\nthe local density of states of the graphitic nanocone. This influence depends\non the number of defects present at the tip of the nanocone. This property\ncould be applied in atomic force microscopy for the construction of the probing\ntip."
    },
    {
        "anchor": "Spin-vorticity coupling in viscous electron fluids: We consider spin-vorticity coupling - the generation of spin polarization by\nvorticity - in viscous two-dimensional electron systems with spin-orbit\ncoupling. We first derive hydrodynamic equations for spin and momentum\ndensities in which their mutual coupling is determined by the rotational\nviscosity. We then calculate the rotational viscosity microscopically in the\nlimits of weak and strong spin-orbit coupling. We provide estimates that show\nthat the spin-orbit coupling achieved in recent experiments is strong enough\nfor the spin-vorticity coupling to be observed. On the one hand, this coupling\nprovides a way to image viscous electron flows by imaging spin densities. On\nthe other hand, we show that the spin polarization generated by spin-vorticity\ncoupling in the hydrodynamic regime can, in principle, be much larger than that\ngenerated, e.g. by the spin Hall effect, in the diffusive regime.",
        "positive": "Electronic properties of bilayer graphene catenoid bridge: We study the properties of an electron on a catenoid surface. The catenoid is\nunderstood as a realization of a bridge connecting two graphene layer by a\nsmooth surface. The curvature induces a symmetrical reflectionless potential\nwell around the bridge with one bound-state for $m=0$. For $m\\neq 0$, a\ncentrifugal potential barrier arises controlling the tunnelling between the\nlayers. An external electric field breaks the parity symmetry and provides a\nbarrier that controls the conductance from one layer to another. By applying a\nconstant magnetic field the effective potential exhibits a confining\ndouble-well potential nearby the bridge. We obtain the corresponding bound\nstates and study the effects of the curvature on the Landau levels."
    },
    {
        "anchor": "Evidence for broken Galilean invariance at the quantum spin Hall edge: We study transport properties of the helical edge channels of a quantum spin\nHall (QSH) insulator, in the presence of electron-electron interactions and\nweak, local Rashba spin-orbit coupling. The combination of the two allows for\ninelastic backscattering that does not break time-reversal symmetry (TRS),\nresulting in interaction-dependent power law corrections to the conductance.\nHere, we use a non-equilibrium Keldysh formalism to describe the situation of a\nlong, one-dimensional edge channel coupled to external reservoirs, where the\napplied bias is the leading energy scale. By calculating explicitly the\ncorrections to the conductance up to fourth order of the impurity strength, we\nanalyse correlated single- and two-particle backscattering processes on a\nmicroscopic level. Interestingly, we show that the modeling of the leads\ntogether with the breaking of Galilean invariance has important consequences on\nthe transport properties. Such breaking occurs, because the Galilean invariance\nof the bulk spectrum transforms into an emergent Lorentz invariance of the edge\nspectrum. With this broken Galilean invariance at the QSH edge, we find a\ncontribution to single particle backscattering with a very low power scaling,\nwhile in the presence of Galilean invariance the leading contribution would be\ndue to correlated two-particle backscattering only. This difference is further\nreflected in different values of the Fano factor of the shot noise, an\nexperimentally observable quantity. The described behaviour is specific to the\nRashba scatterer, and does not occur in the case of backscattering off a\ntime-reversal breaking, magnetic impurity.",
        "positive": "Dissipationless gyrotropic magnetic Hall effect: A dissipationless longitudinal current can be generated by a pure magnetic\nfield through the chiral magnetic effect. Herein, we propose that a pure\noscillating magnetic field through Zeeman coupling can further drive an AC\nmagnetic Hall current in two-dimensional systems without inversion symmetry. We\ndub this effect the \"gyrotropic magnetic Hall effect\" (GMHE), in analogy with\nthe gyrotropic current achieved by rectifying the optical fields. Importantly,\nwe find that the GMHE conductivity is a reactive or dissipationless transport\ncoefficient, which is even under time-reversal symmetry. We reveal the \"Zeeman\nBerry curvature\" as the quantum origin of the GMHE, whose integral over all\nstates below the Fermi energy gives the GMHE conductivity. Furthermore, by\nsymmetry analysis, we show that the GMHE can appear in a wide range of\ntwo-dimensional materials. To demonstrate our proposal, we evaluate the GMHE\ncurrent in two-dimensional Rashba system and in the surface of topological\ninsulator, where a low-frequency magnetic field with a small amplitude can be\nconverted into a detectable Hall voltage."
    },
    {
        "anchor": "Quantum theory of spectral diffusion induced electron spin decoherence: A quantum cluster expansion method is developed for the problem of localized\nelectron spin decoherence due to dipolar fluctuations of lattice nuclear spins.\nAt the lowest order it provides a microscopic explanation for the Lorentzian\ndiffusion of Hahn echoes without resorting to any phenomenological Markovian\nassumption. Our numerical results show remarkable agreement with recent\nelectron spin echo experiments in phosphorus doped silicon.",
        "positive": "Magnetoelectric coupling in superconductor-helimagnet heterostructures: The Ginzburg-Landau free energy of a conventional superconductor coupled to a\nhelimagnet is microscopically derived using functional field integral\ntechniques. We show that the spin texture leads to a Lifshitz invariant in the\nfree energy, which couples the momentum density of the superconducting\ncondensate to the magnetization of the helimagnet. For helimagnets with a\nconical texture, the Lifshitz invariant yields a spatial modulation of the\nsuperconducting phase along the helical wavevector of the magnetic texture.\nBased on self-consistent numerical calculations, we verify the theoretical\nformalism by investigating a superconductor that contains a helical\nYu-Shiba-Rusinov (YSR) chain. We demonstrate that the texture-induced\nmagnetoelectric coupling produces a strong supercurrent along the YSR chain,\nwhich induces a detectable magnetic field."
    },
    {
        "anchor": "Soft Magnons in Anisotropic Ferromagnets: We discuss spin-wave transport in anisotropic ferromagnets with an emphasis\non the zeroes of the band edges as a function of a magnetic field. An\nassociated divergence of the magnon spin should be observable by enhanced\nmagnon conductivities in non-local experiments, especially in two-dimensional\nferromagnets.",
        "positive": "Decoherence in Andreev spin qubits: We theoretically study the dephasing of an Andreev spin qubit (ASQ) due to\nelectric and magnetic noise. Using a tight-binding model, we calculate the\nAndreev states formed in a Josephson junction where the link is a semiconductor\nwith strong spin-orbit interaction. As a result of both the spin-orbit\ninteraction and induced superconductivity, the local charge and spin of these\nstates varies as a function of externally controllable parameters: the phase\ndifference between the superconducting leads, an applied magnetic field, and\nfilling of the underlying semiconductor. Concomitantly, coupling to\nfluctuations of the electric or magnetic environment will vary, which informs\nthe rate of dephasing. We qualitatively predict the dependence of dephasing on\nthe nature of the environment, magnetic field, phase difference between the\njunction, and filling of the semiconductor. Comparing the simulated electric-\nand magnetic-noise-induced dephasing rate to experiment suggests that the\ndominant source of noise is magnetic. Moreover, by appropriately tuning these\nexternal parameters, we find sweet-spots at which we predict an enhancement in\nASQ coherence times."
    },
    {
        "anchor": "Low-Temperature Conductivity of Weakly Interacting Quantum Spin Hall\n  Edges in Strained-Layer InAs/GaInSb: We report low-temperature transport measurements in strained\nInAs/Ga0.68In0.32Sb quantum wells, which supports time-reversal\nsymmetry-protected helical edge states. The temperature and bias voltage\ndependence of the helical edge conductance for devices of various sizes are\nconsistent with the theoretical expectation of a weakly interacting helical\nedge state. Moreover, we found that the magnetoresistance of the helical edge\nstates is related to the edge interaction effect and the disorder strength.",
        "positive": "Spin noise at electron paramagnetic resonance: We develop a microscopic theory of spin noise in solid-state systems at\nelectron paramagnetic resonance, when the spin dynamics is driven by static and\nradio-frequency (RF) magnetic fields and the stochastic effective magnetic\nfield stemming from the interaction with environment. The RF field splits the\npeaks in the power spectrum of spin noise into the Mollow-like triplets and\nalso gives rise to additional spin-spin correlations which oscillate in the\nabsolute time at the RF frequency and the double frequeqncy. Even in systems\nwith strong inhomogeneous broadening, the spin noise spectrum contains narrow\nlines insensitive to the dispersion of the effective $g$-factors. Thus, the\nmeasurements of spin noise at electron paramagnetic resonance provides an\naccess to the intrinsic spin lifetime of electrons."
    },
    {
        "anchor": "Entropic transport of finite size particles: Transport of spherical Brownian particles of finite size possessing radii\nthrough narrow channels with varying cross-section area is considered. Applying\nthe so-called Fick-Jacobs approximation, i.e. assuming fast equilibration in\northogonal direction of the channel axis, the 2D problem can be described by a\n1D effective dynamics in which bottlenecks cause entropic barriers. Geometrical\nconfinements result in entropic barriers which the particles have to overcome\nin order to proceed in transport direction. The analytic findings for the\nnonlinear mobility for the transport are compared with precise numerical\nsimulation results. The dependence of the nonlinear mobility on the particle\nsize exhibits a striking resonance-like behavior as a function of the relative\nparticle size; this latter feature renders possible new effective particle\nseparation scenarios.",
        "positive": "Polarization dependence of double resonant Raman scattering band in\n  bilayer graphene: The polarization dependence of the double resonant Raman scattering (2D) band\nin bilayer graphene (BLG) is studied as a function of the excitation laser\nenergy. It has been known that the complex shape of the 2D band of BLG can be\ndecomposed into four Lorentzian peaks with different Raman frequency shifts\nattributable to four individual scattering paths in the energy-momentum space.\nFrom our polarization dependence study, however, we reveal that each of the\nfour different peaks is actually doubly degenerate in its scattering channels,\ni.e., two different scattering paths with similar Raman frequency shifts for\neach peak. We find theoretically that one of these two paths, ignored for a\nlong time, has a small contribution to their scattering intensities but are\ncritical in understanding their polarization dependences. Because of this, the\nmaximum-to-minimum intensity ratios of the four peaks show a strong dependence\non the excitation energy, unlike the case of single-layer graphene (SLG). Our\nfindings thus reveal another interesting aspect of electron-phonon interactions\nin graphitic systems."
    },
    {
        "anchor": "Electron hopping heat transport in molecules: The realization of single-molecule thermal conductance measurements has\ndriven the need for theoretical tools to describe conduction processes that\noccur over atomistic length scales. In macroscale systems, the principle that\nis typically used to understand thermal conductivity is Fourier's law. At\nmolecular length scales, however, deviations from Fourier's law are common in\npart because microscale thermal transport properties typically depend on the\ncomplex interplay between multiple heat conduction mechanisms. Here, the\nthermal transport properties that arise from electron transfer across a thermal\ngradient in a molecular conduction junction are examined theoretically. We\nillustrate how transport in a model junction is affected by varying the\nelectronic structure and length of the molecular bridge in the junction as well\nas the strength of the coupling between the bridge and its surrounding\nenvironment. Three findings are of note: First, the transport properties can\nvary significantly depending on the characteristics of the molecular bridge and\nits environment; second, the system's thermal conductance commonly deviates\nfrom Fourier's law; and third, in properly engineered systems, the magnitude of\nelectron hopping thermal conductance is similar to what has been measured in\nsingle-molecule devices.",
        "positive": "Polarized neutron reflectometry study from iron oxide nanoparticles\n  monolayer: We report on the polarized neutron reflectometry investigation of monolayer\nof magnetic iron oxide nanoparticles assembled by the Langmuir-Schaefer method.\nAfter deposition onto a solid substrate the polarized neutron reflectometry\nmeasurements in the external magnetic field were carried out. Thickness,\ndensity, roughness and in-depth resolved magnetization profile of the resulted\nlayer were obtained from accurate fitting routine."
    },
    {
        "anchor": "Magnon magic angles and tunable Hall conductivity in 2D twisted\n  ferromagnetic bilayers: Twistronics is currently one of the most active research fields in condensed\nmatter physics, following the discovery of correlated insulating and\nsuperconducting phases in twisted bilayer graphene (tBLG). Here, we present a\nmagnonic analogue of tBLG. We study magnons in twisted ferromagnetic bilayers\n(tFBL), including exchange and Dzyaloshinskii-Moriya interactions (DMI). For\nnegligible DMI, tFBL presents discrete magnon magic angles and flat moir\\'e\nminibands analogous to tBLG. The DMI, however, changes the picture and renders\nthe system much more exotic. The DMI in tFBL induces a rich topological magnon\nband structure for any twist angle. The twist angle turns to a control knob for\nthe magnon Hall and Nernst conductivities. Gapped flat bands appear in a\ncontinuum of magic angles in tFBL with DMI. In the lower limit of the\ncontinuum, the band structure reconstructs to form bundles of topological flat\nbands. The luxury of twist-angle control over band gaps, topological\nproperties, number of flat bands, Hall and Nernst conductivities renders tFBL a\nnovel device from fundamental and applied perspectives.",
        "positive": "Monitoring superparamagnetic Langevin behavior of individual ${\\rm\n  SrRuO_3}$ nanostructures: Patterned nanostructures on the order of 200 nm $\\times$ 200 nm of the\nitinerant ferromagnet ${\\rm SrRuO_3}$ give rise to superparamagnetic behavior\nbelow the Curie temperature (${\\rm \\sim 150 \\ K}$) down to a sample-dependent\nblocking temperature. We monitor the superparamagnetic fluctuations of an\nindividual volume and demonstrate that the field dependence of the\ntime-averaged magnetization is well described by the Langevin equation. On the\nother hand, the rate of the fluctuations suggests that the volume in which the\nmagnetization fluctuates is smaller by more than an order of magnitude. We\nsuggest that switching via nucleation followed by propagation gives rise to\nLangevin behavior of the total volume, whereas the switching rate is determined\nby a much smaller nucleation volume."
    },
    {
        "anchor": "Fast and high-fidelity dispersive readout of a spin qubit via squeezing\n  and resonator nonlinearity: Fast and high-fidelity qubit measurement is crucial for achieving quantum\nerror correction, a fundamental element in the development of universal quantum\ncomputing. For electron spin qubits, fast readout stands out as a major\nobstacle in the pursuit of error correction. In this work, we explore the\ndispersive measurement of an individual spin in a semiconductor double quantum\ndot coupled to a nonlinear microwave resonator. By utilizing displaced squeezed\nvacuum states, we achieve rapid and high-fidelity readout for semiconductor\nspin qubits. Our findings reveal that introducing modest squeezing and mild\nnonlinearity can significantly improve both the signal-to-noise ratio (SNR) and\nthe fidelity of qubit-state readout. By properly marching the phases of\nsqueezing, the nonlinear strength, and the local oscillator, the optimal\nreadout time can be reduced to the sub-microsecond range. With current\ntechnology parameters ($\\kappa\\approx 2\\chi_s$, $\\chi_s\\approx 2\\pi\\times 0.15\n\\:\\mbox{MHz}$), utilizing a displaced squeezed vacuum state with $30$ photons\nand a modest squeezing parameter $r\\approx 0.6$, along with a nonlinear\nmicrowave resonator charactered by a strength of $\\lambda\\approx -1.2 \\chi_s$,\na readout fidelity of $98\\%$ can be attained within a readout time of around\n$0.6\\:\\mu\\mbox{s}$. Intriguing, by using a positive nonlinear strength of\n$\\lambda\\approx 1.2\\chi_s$, it is possible to achieve an SNR of approximately\n$6$ and a readout fidelity of $99.99\\%$ at a slightly later time, around\n$0.9\\:\\mu\\mbox{s}$, while maintaining all other parameters at the same\nsettings.",
        "positive": "First principle investigation of Tunnel FET based on nanoribbons from\n  topological two-dimensional material: We explore nanoribbons from topological two-dimensional stanene as channel\nmaterial in tunnel field effect transistors. This novel technological option\noffers the possibility to build pure one-dimensional (1D) channel devices\n(comprised of a 1D chain of atoms) due to localized states in correspondence of\nthe nanoribbon edges. The investigation is based on first-principle\ncalculations and multi-scale transport simulations to assess devices\nperformance against industry requirements and their robustness with respect to\ntechnological issues like line edge roughness, detrimental for nanoribbons. We\nwill show that edges states are robust with respect to the presence of\nnon-idealities (e.g., atoms vacancies at the edges), and that 1D-channel TFETs\nexhibit interesting potential for digital applications and room for\noptimization in order to improve the Ion/Ioff at the levels required by the\nITRS, while opening a path for the exploration of new device concepts at the\nultimate scaling limits."
    },
    {
        "anchor": "Shot noise of a ferromagnetic nanowire with a domain wall: We study shot noise of the spin-polarized current in a diffusive\nferromagnetic nanowire which contains a ballistic domain wall. We find that the\nexistence of a short domain wall influences strongly the shot noise for\nsufficiently high spin-polarization of the wire. Compared to the situation of\nthe absence of the domain wall, the shot noise can be reduced or enhanced\ndepending on the length of the domain wall and its relative conductance.",
        "positive": "Atomistic spin textures on-demand in the van der Waals layered magnet\n  CrSBr: Controlling magnetism in low dimensional materials is essential for designing\ndevices that have feature sizes comparable to several critical length scales\nthat exploit functional spin textures, allowing the realization of low-power\nspintronic and magneto-electric hardware. [1] Unlike conventional\ncovalently-bonded bulk materials, van der Waals (vdW)-bonded layered magnets\n[2-4] offer exceptional degrees of freedom for engineering spin textures. [5]\nHowever, their structural instability has hindered microscopic studies and\nmanipulations. Here, we demonstrate nanoscale structural control in the layered\nmagnet CrSBr creating novel spin textures down to the atomic scale. We show\nthat it is possible to drive a local structural phase transformation using an\nelectron beam that locally exchanges the bondings in different directions,\neffectively creating regions that have vertical vdW layers embedded within the\nhorizontally vdW bonded exfoliated flakes. We calculate that the newly formed\n2D structure is ferromagnetically ordered in-plane with an energy gap in the\nvisible spectrum, and weak antiferromagnetism between the planes. Our study\nlays the groundwork for designing and studying novel spin textures and related\nquantum magnetic phases down to single-atom sensitivity, potentially to create\non-demand spin Hamiltonians probing fundamental concepts in physics, [6-10] and\nfor realizing high-performance spintronic, magneto-electric and topological\ndevices with nanometer feature sizes. [11,12]"
    },
    {
        "anchor": "Observation of structural universality in disordered systems using bulk\n  diffusion measurement: We report on an experimental observation of classical diffusion\ndistinguishing between structural universality classes of disordered systems in\none dimension. Samples of hyperuniform and short-range disorder were designed,\ncharacterized by the statistics of the placement of $\\mu$m-thin parallel\npermeable barriers, and the time-dependent diffusion coefficient was measured\nby NMR methods over three orders of magnitude in time. The relation between the\nstructural exponent, characterizing disorder universality class, and the\ndynamical exponent of the diffusion coefficient is experimentally verified. The\nexperimentally established relation between structure and transport exemplifies\nthe hierarchical nature of structural complexity --- dynamics are mainly\ndetermined by the universality class, whereas microscopic parameters affect the\nnon-universal coefficients. These results open the way for non-invasive\ncharacterization of structural correlations in porous media, complex materials,\nand biological tissues via a bulk diffusion measurement.",
        "positive": "Fractal Self-Assembled Nanostructures on Monocrystalline Silicon Surface: We present ultra-shallow diffusion profiles performed by short-time diffusion\nof boron from the gas phase using controlled surface injection of\nself-interstitials and vacancies into the n-type Si(100) wafers. The diffusion\nprofiles of this art are found to consist of both longitudinal and lateral\nsilicon quantum wells of the p-type that are self-assembled between the alloys\nof microdefects, which are produced by previous oxidation. These alloys appear\nto be passivated during short-time diffusion of boron thereby forming neutral\ndel'ta barriers. The fractal type self-assembly of microdefects is found to be\ncreated by varying the thickness of the oxide overlayer, which causes the\nsystem of microcavities embedded in the quantum well plane."
    },
    {
        "anchor": "Thermal motions in complex liquids: the 2D Lennard-Jones liquid: Thermal motions in the 2D Lennard-Jones liquid near solidification are\nstudied at equilibrium and under shear flow conditions. At the temperatures of\nthe study, the liquid is significantly aggregated. On times of few to few tens\nof particles vibration periods, the dominant features are particles in-cage\nvibrations and the highest frequency longitudinal and transverse Hypersound. On\ntime-scales of hundreds to thousands of vibration periods, the liquid appears\nspatially heterogeneous. On these times, slow non-oscillatory fluctuating\ncurrents persist for surprisingly long times; the hierarchical dynamics of the\nheterogeneous liquid results in changing temperature, density, and velocity\nprofiles across the system. Heterogeneity fades, and a crossover to\nnon-fluctuational Hydrodynamics is observed for smoothing times of many tens of\nthousands vibration periods. On these asymptotically-large times, the liquid is\nspatially homogeneous except for thin layers near the boundaries where the\ndegree of crystallinity increases and the mobility decreases due to\nliquid-boundary interactions.",
        "positive": "Accessing different topological classes and types of Majorana edge\n  states in coupled superconducting platforms using perturbations: The study of topological classes and their associated edge states has been of\nongoing interest. In one dimension, the standard platform of these studies has\nbeen the conventional Kitaev wire and its realizations. In this work, we study\nthe edge states in coupled p-wave platforms in 1D, in the presence of\nexperimentally relevant perturbations, like a Zeeman field and s-wave SC.\nFirstly, we show that the unperturbed coupled p-wave setup by itself can have\ntwo types of Majorana edge states, depending on the value of the effective\nonsite potential. We show that additional components like Zeeman field and\ns-wave term can cause transitions to different symmetry classes, both\ntopologically trivial or non-trivial, and change the nature of these edge\nstates. In the presence of the perturbations, we show that there are 3 symmetry\nclasses when the effective p-wave pairing is equal between the spin species,\nand 6 for the second kind, when the pairing differs by a phase $\\pi$ between\nthe two. Some of these classes are topologically non-trivial. Further, we\nexplore the nature of subgap states when we have a junction between two such\ntopological setups and their corresponding behaviour with the phase of the\np-wave order parameter. Our work provides a theoretical framework of the\ndifferent ways to get non-trivial topological classes in coupled p-wave\nnanowire setup, using experimentally feasible perturbations, and the nature of\nsubgap states across junctions of these platforms."
    },
    {
        "anchor": "Signatures of topology in ballistic bulk transport of HgTe quantum wells: We calculate bulk transport properties of two-dimensional topological\ninsulators based on HgTe quantum wells in the ballistic regime. Interestingly,\nwe find that the conductance and the shot noise are distinctively different for\nthe so-called normal regime (the topologically trivial case) and the so-called\ninverted regime (the topologically non-trivial case). Thus, it is possible to\nverify the topological order of a two-dimensional topological insulator not\nonly via observable edge properties but also via observable bulk properties.\nThis is important because we show that under certain conditions the bulk\ncontribution can dominate the edge contribution which makes it essential to\nfully understand the former for the interpretation of future experiments in\nclean samples.",
        "positive": "Magnetic Resonance Force Microscopy with Overlapping Frequencies of\n  Cantilever and Spin: We have studied theoretically magnetic resonance force microscopy (MRFM) with\na high frequency nanomechanical cantilever when the cantilever frequency\nmatches the resonant frequency of a single electron spin. Our estimations show\nthat in this scenario the relative frequency shift of the cantilever can be\nmuch greater than the record MRFM frequency shift achieved in experiments with\na single spin detection. Experimental realization of our proposal could open\nthe way for fast detection of a single electron spin and even for detection of\na single nuclear spin."
    },
    {
        "anchor": "Tailoring Dzyaloshinskii-Moriya interaction in a transition metal\n  dichalcogenide by dual-intercalation: Dzyaloshinskii-Moriya interaction (DMI) is vital to form various chiral spin\ntextures, novel behaviors of magnons and permits their potential applications\nin energy-efficient spintronic devices. Here, we realize a sizable bulk DMI in\na transition metal dichalcogenide (TMD) 2H-TaS2 by intercalating Fe atoms,\nwhich form the chiral supercells with broken spatial inversion symmetry and\nalso act as the source of magnetic orderings. Using a newly developed protonic\ngate technology, gate-controlled protons intercalation could further change the\ncarrier density and intensely tune DMI via the Ruderman-Kittel-Kasuya-Yosida\nmechanism. The resultant giant topological Hall resistivity of 1.4 uohm.cm at\n-5.2V (about 460% of the zero-bias value) is larger than most of the known\nmagnetic materials. Theoretical analysis indicates that such a large\ntopological Hall effect originates from the two-dimensional Bloch-type chiral\nspin textures stabilized by DMI, while the large anomalous Hall effect comes\nfrom the gapped Dirac nodal lines by spin-orbit interaction. Dual-intercalation\nin 2HTaS2 provides a model system to reveal the nature of DMI in the large\nfamily of TMDs and a promising way of gate tuning of DMI, which further enables\nan electrical control of the chiral spin textures and related electromagnetic\nphenomena.",
        "positive": "Multifractally-enhanced superconductivity in thin films: The multifractal superconducting state originates from the interplay of\nAnderson localization and interaction effects. In this article we overview the\nrecent theory of the superconductivity enhancement by multifractality and\nextend it to describe the spectral properties of superconductors on the scales\nof the order of the superconducting gap. Specifically, using the approach based\non renormalization group within the nonlinear sigma model, we develop the\ntheory of a multifractal superconducting state in thin films. We derive a\nmodified Usadel equation that incorporates the interplay of disorder and\ninteractions at energy scales larger than the spectral gap and study the effect\nof such an interplay on the low-energy physics. We determine the spectral gap\nat zero temperature which occurs to be proportional to the multifracally\nenhanced superconducting transition temperature. The modified Usadel equation\nresults in the disorder-averaged density of states that, near the spectral gap,\nresembles the one obtained in the model of a spatially random superconducting\norder parameter. We reveal strong mesoscopic fluctuations of the local density\nof states in the superconducting state. Such strong mesoscopic fluctuations\nimply that the interval of energies in which the superconducting gap\nestablishes is parametrically large in systems with multifractally-enhanced\nsuperconductivity."
    },
    {
        "anchor": "Momentum-resolved view of highly tunable many-body effects in a\n  graphene/hBN field-effect device: Integrating the carrier tunability of a functional two-dimensional material\nelectronic device with a direct probe of energy- and momentum-resolved\nelectronic excitations is essential to gain insights on how many-body\ninteractions are influenced during device operation. Here, we use micro-focused\nangle-resolved photoemission in order to analyze many-body interactions in\nback-gated graphene supported on hexagonal boron nitride. By extracting the\ndoping-dependent quasiparticle dispersion and self-energy, we observe how these\ninteractions renormalize the Dirac cone and impact the electron mobility of our\ndevice. Our results are not only limited to a finite energy range around the\nFermi level, as in electron transport measurements, but describe interactions\non a much wider energy scale, extending beyond the regime of hot carrier\nexcitations.",
        "positive": "Current induced vortex superlattices in nanomagnets: Influence of the spin-transfer torque on the vortex state magnetic nanodisk\nis studied numerically via Slonczewski-Berger mechanism. The existence of a\ncritical current is determined for the case of same-directed electrical\ncurrent, its spin polarization and polarity of the vortex. The critical current\nseparates two regimes: (i) deformed but static vortex state and (ii)\nessentially dynamic state under which the spatio-temporal periodic structures\ncan appear. The structure is a stable vortex-antivortex lattice. Symmetry of\nthe lattice depends on the applied current value and for high currents (close\nto saturation) only square lattices are observed. General relations for sizes\nof the stable lattice is obtained analytically."
    },
    {
        "anchor": "Uniform current in graphene strip with zigzag edges: Graphene exhibits zero-gap massless-Dirac fermion and zero density of states\nat E = 0. These particles form localized states called edge states on finite\nwidth strip with zigzag edges at E = 0. Naively thinking, one may expect that\ncurrent is also concentrated at the edge, but Zarbo and Nikolic numerically\nobtained a result that the current density shows maximum at the center of the\nstrip. We derive a rigorous relation for the current density, and clarify the\nreason why the current density of edge state has a maximum at the center.",
        "positive": "Resonance fluorescence and laser spectroscopy of three-dimensionally\n  confined excitons in monolayer WSe$_2$: Resonant optical excitation of few-level quantum systems enables coherent\nquantum control, resonance fluorescence, and direct characterization of\ndephasing mechanisms. Experimental demonstrations have been achieved in a\nvariety of atomic and solid-state systems. An alternative but intriguing\nquantum photonic platform is based on single layer transition metal\nchalcogenide semiconductors, which exhibit a direct band-gap with optically\naddressable exciton valley-pseudospins in a uniquely two-dimensional form. Here\nwe perform resonance and near-resonance excitation of three-dimensionally\nconfined excitons in monolayer WSe$_2$ to reveal near ideal single photon\nfluorescence with count rates up to 3 MHz and uncover a weakly-fluorescent\nexciton state ~ 5 meV blue-shifted from the ground-state exciton. We perform\nhigh-resolution photoluminescence excitation spectroscopy of the localized\nexcitons, providing important information to unravel the precise nature of the\nquantum states. Successful demonstration of resonance fluorescence paves the\nway to probe the localized exciton coherence. Moreover, these results yield a\nroute for investigations of the spin and valley coherence of confined excitons\nin two-dimensional semiconductors."
    },
    {
        "anchor": "Terahertz light-matter interaction beyond unity coupling strength: Achieving control over light-matter interaction in custom-tailored\nnanostructures is at the core of modern quantum electrodynamics [1-15]. In\nultrastrongly coupled systems [5-15], excitation is repeatedly exchanged\nbetween a resonator and an electronic transition at a rate known as the vacuum\nRabi frequency $\\Omega_R$. For $\\Omega_R$ approaching the resonance frequency\n$\\omega_c$, novel quantum phenomena including squeezed states [16], Dicke\nsuperradiant phase transitions [17,18], the collapse of the Purcell effect\n[19], and a population of the ground state with virtual photon pairs [16,20]\nare predicted. Yet, the experimental realization of optical systems with\n$\\Omega_R$/$\\omega_c$ has remained elusive. Here, we introduce a paradigm\nchange in the design of light-matter coupling by treating the electronic and\nthe photonic components of the system as an entity instead of optimizing them\nseparately. Using the electronic excitation to not only boost the oscillator\nstrength but furthermore tailor the shape of the vacuum mode, we push\n$\\Omega_R$/$\\omega_c$ of cyclotron resonances ultrastrongly coupled to\nmetamaterials far beyond unity. As one prominent illustration of the unfolding\npossibilities, we calculate a ground state population of 0.37 virtual photons\nfor our best structure with $\\Omega_R$/$\\omega_c$ = 1.43, and suggest a\nrealistic experimental scenario for measuring vacuum radiation by cutting-edge\nterahertz quantum detection [21,22].",
        "positive": "Coherent spin dynamics of electrons and holes in semiconductor quantum\n  wells and quantum dots under periodical optical excitation: resonant spin\n  amplification versus spin mode-locking: The coherent spin dynamics of resident carriers, electrons and holes, in\nsemiconductor quantum structures is studied by periodical optical excitation\nusing short laser pulses and in an external magnetic field. The generation and\ndephasing of spin polarization in an ensemble of carrier spins, for which the\nrelaxation time of individual spins exceeds the repetition period of the laser\npulses, are analyzed theoretically. Spin polarization accumulation is\nmanifested either as resonant spin amplification or as mode-locking of carrier\nspin coherences. It is shown that both regimes have the same origin, while\ntheir appearance is determined by the optical pump power and the spread of spin\nprecession frequencies in the ensemble."
    },
    {
        "anchor": "Impossibility of Increasing N$\\acute{\\textrm{e}}$el Temperature in\n  Zigzag Graphene Nanoribbon by Electric Field and Carrier Doping: We investigated the dependence of N$\\acute{\\textrm{e}}$el temperature as a\ncritical temperature on the electric field and hole-electron doping in the\nantiferromagnetically ordered zigzag graphene nanoribbon. The temperature was\ncalculated by averaging the magnon energy in the Brillouin zone within the\nmean-field approximation. We employed the generalized Bloch theorem instead of\nthe supercell approach to reduce the computational cost significantly to obtain\nthe magnon spectrum. We showed that the N$\\acute{\\textrm{e}}$el temperature\nreduces when increasing both the electric field and the hole-electron doping,\nthus these treatments will never enhance the N$\\acute{\\textrm{e}}$el\ntemperature.",
        "positive": "Stepwise relaxation and stochastic precession in degenerate oscillators\n  dispersively coupled to particles: By numerical integration, we study the relaxation dynamics of degenerate\nharmonic oscillator modes dispersively coupled to particle positions. Depending\non whether the effective inertial potential induced by the oscillators keep the\nparticles confined, or if the particle trajectories traverse the system, the\nlocal oscillator energy dissipation rate changes drastically. The inertial\ntrapping, release and retrapping of particles results in a characteristic\nstep-wise relaxation process, with alternating regions of fast and slow\ndissipation. To demonstrate this phenomenon we consider first a one-dimensional\nminimal prototype model which displays these characteristics. We then treat the\neffect of dispersive interaction in a model corresponding to an adsorbate\ndiffusing on a circular membrane interacting with its three lowest vibrational\nmodes. In the latter model, stepwise relaxation appears only in the presence of\nthermal noise, which also causes a slow-in-time stochastic precession of the\nmixing angle between the degenerate eigenmodes."
    },
    {
        "anchor": "Nonlocal Thermoelectric Effects and Nonlocal Onsager Relations in a\n  Three-Terminal Proximity-Coupled Superconductor-Ferromagnet Device: We study thermal and charge transport in a three-terminal setup consisting of\none superconducting and two ferromagnetic contacts. We predict that the\nsimultaneous presence of spin filtering and of spin- dependent scattering phase\nshifts at each of the two interfaces will lead to very large nonlocal thermo-\nelectric effects both in clean and in disordered systems. The symmetries of\nthermal and electric transport coefficients are related to fundamental\nthermodynamic principles by the Onsager reciprocity. Our results show that a\nnonlocal version of the Onsager relations for thermoelectric currents holds in\na three-terminal quantum coherent ferromagnet-superconductor heterostructure\nincluding a spin-dependent crossed Andreev reflection and coherent electron\ntransfer processes.",
        "positive": "Fast high-fidelity single-shot readout of spins in silicon using a\n  single-electron box: Three key metrics for readout systems in quantum processors are measurement\nspeed, fidelity and footprint. Fast high-fidelity readout enables mid-circuit\nmeasurements, a necessary feature for many dynamic algorithms and quantum error\ncorrection, while a small footprint facilitates the design of scalable,\nhighly-connected architectures with the associated increase in computing\nperformance. Here, we present two complementary demonstrations of fast\nhigh-fidelity single-shot readout of spins in silicon quantum dots using a\ncompact, dispersive charge sensor: a radio-frequency single-electron box. The\nsensor, despite requiring fewer electrodes than conventional detectors,\nperforms at the state-of-the-art achieving spin read-out fidelity of 99.2% in\nless than 6 $\\mu$s. We demonstrate that low-loss high-impedance resonators,\nhighly coupled to the sensing dot, in conjunction with Josephson parametric\namplification are instrumental in achieving optimal performance. We quantify\nthe benefit of Pauli spin blockade over spin-dependent tunneling to a\nreservoir, as the spin-to-charge conversion mechanism in these readout schemes.\nOur results place dispersive charge sensing at the forefront of readout\nmethodologies for scalable semiconductor spin-based quantum processors."
    },
    {
        "anchor": "Enhancing optomechanical coupling via the Josephson effect: Cavity optomechanics is showing promise for studying quantum mechanics in\nlarge systems. However, smallness of the radiation-pressure coupling is a\nserious hindrance. Here we show how the charge tuning of the Josephson\ninductance in a single-Cooper-pair transistor (SCPT) can be exploited to\narrange a strong radiation pressure -type coupling $g_0$ between mechanical and\nmicrowave resonators. In a certain limit of parameters, such a coupling can\nalso be seen as a qubit-mediated coupling of two resonators. We show that this\nscheme allows reaching extremely high $g_0$. Contrary to the recent proposals\nfor exploiting the non-linearity of a large radiation pressure coupling, the\nmain non-linearity in this setup originates from a cross-Kerr type of coupling\nbetween the resonators, where the cavity refractive index depends on the phonon\nnumber. The presence of this coupling will allow accessing the individual\nphonon numbers via the measurement of the cavity.",
        "positive": "Flux $1/f^\u03b1$ noise in 2D Heisenberg spin glasses: effects of weak\n  anisotropic interactions: We study the dynamics of a two-dimensional ensemble of randomly distributed\nclassical Heisenberg spins with isotropic RKKY and weaker anisotropic\ndipole-dipole couplings. Such ensembles may give rise to the flux noise\nobserved in SQUIDs with a $1/f^{\\alpha}$ power spectrum ($\\alpha \\lesssim 1$).\nWe solve numerically the Landau-Lifshiftz-Gilbert equations of motion in the\ndissipationless limit. We find that Ising type fluctuators, which arise from\nspin clustering close to a spin-glass critical behavior with $T_c =0$, give\nrise to $1/f^{\\alpha}$ noise. Even weak anisotropic interactions lead to a\ncrossover from the Heisenberg-type criticality to the much stronger Ising-type\ncriticality. The temperature dependent exponent $\\alpha(T) \\lesssim 1$ grows\nand approaches unity when the temperature is lowered. This mechanism acts in\nparallel to the spin diffusion mechanism. Whereas the latter is sensitive to\nthe device geometry, the spin-clustering mechanism is largely geometry\nindependent."
    },
    {
        "anchor": "Limit cycle theory of temporal current self-oscillations in sequential\n  tunneling of superlattices: A unified theory of the temporal current self-oscillations is presented. We\nestablish these oscillations as the manifestations of limit cycles, around\nunstable steady-state solutions caused by the negative differential\nconductance. This theory implies that both the generation and the motion of an\nelectric-field domain boundary are universal in the sense that they do not\ndepend on the initial conditions. Under an extra weak ac bias with a frequency\n$\\omega_{ac}$, the frequency must be either $\\omega_{ac}$ or an integer\nfractional of $\\omega_{ac}$ if the tunneling current oscillates periodically in\ntime, indicating the periodic doubling for this non-linear dynamical system",
        "positive": "Penetration of a magnetic wall into thin ferromagnetic electrodes of a\n  nano-contact spin valve: We theoretically analyzed a magnetic wall confined in a nano-contact spin\nvalve paying special attention to the penetration of the magnetic wall into\nthin ferromagnetic electrodes. We showed that, compared with the Bloch wall,\nthe penetration of the Neel wall is suppressed by increases of the\ndemagnetization energy. We found the optimal conditions of the radius and\nheight of the nano-contact to maximize the power of the current-induced\noscillation of the magnetic wall. We also found that the thermal stability of\nthe Bloch wall increases when the nano-contact's radius increases or height\ndecreases."
    },
    {
        "anchor": "Spontaneous doping of the basal plane of MoS2 single-layers through\n  oxygen substitution under ambient conditions: The chemical inertness of the defect-free basal plane confers environmental\nstability to MoS2 single-layers, but it also limits their chemical versatility\nand catalytic activity. The stability of the pristine MoS2 basal plane against\noxidation under ambient conditions is a widely accepted assumption in the\ninterpretation of various studies and applications. However, single-atom level\nstructural investigations reported here reveal that oxygen atoms spontaneously\nincorporate into the basal plane of MoS2 single layers during ambient exposure.\nOur scanning tunneling microscopy investigations reveal a slow oxygen\nsubstitution reaction, upon which individual sulfur atoms are one by one\nreplaced by oxygen, giving rise to solid solution type 2D MoS2-xOx crystals. O\nsubstitution sites present all over the basal plane act as single-atomic active\nreaction centers, substantially increasing the catalytic activity of the entire\nMoS2 basal plane for the electrochemical H2 evolution reaction.",
        "positive": "Gate tunable topological flat bands in twisted monolayer-bilayer\n  graphene: We investigate the band structure of twisted monolayer-bilayer graphene\n(tMBG), or twisted graphene on bilayer graphene (tGBG), as a function of twist\nangles and perpendicular electric fields in search of optimum conditions for\nachieving isolated nearly flat bands. Narrow bandwidths comparable or smaller\nthan the effective Coulomb energies satisfying $U_{\\textrm{eff}} /W \\gtrsim 1$\nare expected for twist angles in the range of $0.3^{\\circ} \\sim 1.5^{\\circ}$,\nmore specifically in islands around $\\theta \\sim 0.5^{\\circ}, \\, 0.85^{\\circ},\n\\,1.3^{\\circ}$ for appropriate perpendicular electric field magnitudes and\ndirections. The valley Chern numbers of the electron-hole asymmetric bands\ndepend intrinsically on the details of the hopping terms in the bilayer\ngraphene, and extrinsically on factors like electric fields or average\nstaggered potentials in the graphene layer aligned with the contacting\nhexagonal boron nitride substrate. This tunability of the band isolation,\nbandwidth, and valley Chern numbers makes of tMBG a more versatile system than\ntwisted bilayer graphene for finding nearly flat bands prone to strong\ncorrelations."
    },
    {
        "anchor": "Why does graphene behave as a weakly interacting system?: We address the puzzling weak-coupling perturbative behavior of graphene\ninteraction effects as manifested experimentally, in spite of the effective\nfine structure constant being large, by calculating the effect of Coulomb\ninteractions on the quasiparticle properties to next-to-leading order in the\nrandom phase approximation (RPA). The focus of our work is graphene suspended\nin vacuum, where electron-electron interactions are strong and the system is\nmanifestly in a nonperturbative regime. We report results for the quasiparticle\nresidue and the Fermi velocity renormalization at low carrier density. The\nsmallness of the next-to-leading order corrections that we obtain demonstrates\nthat the RPA theory converges rapidly and thus, in contrast to the usual\nperturbative expansion in the bare coupling constant, constitutes a\nquantitatively predictive theory of graphene many-body physics for any coupling\nstrength.",
        "positive": "Thermodynamic properties of a magnetically modulated graphene: The effect of magnetic modulation on thermodynamic properties of a graphene\nmonolayer in presence of a constant perpendicular magnetic field is reported\nhere. One-dimensional spatial electric or magnetic modulation lifts the\ndegeneracy of the Landau levels and converts into bands and their band width\noscillates with magnetic field leading to Weiss-type oscillation in the\nthermodynamic properties. The effect of magnetic modulation on thermodynamic\nproperties of a graphene sheet is studied and then compared with electrically\nmodulated graphene and magnetically modulated conventional two-dimensional\nelectron gas (2DEG). We observe Weiss-type and de Haas-van Alphen (dHvA)\noscillations at low and high magnetic field, respectively. There is a definite\nphase difference in Weiss-type oscillations in thermodynamic quantities of\nmagnetically modulated graphene in compare to electrically modulated graphene.\nOn the other hand, the phase remains same and amplitude of the oscillation is\nlarge when compared with the magnetically modulated 2DEG. Explicit asymptotic\nexpressions of density of states and the Helmholtz free energy are provided to\nunderstand the phase and amplitude of the Weiss-type oscillations\nqualitatively. We also study thermodynamic properties when both electric and\nmagnetic modulations are present. The Weiss-type oscillations still exist when\nthe modulations are out-of-phase."
    },
    {
        "anchor": "Suppression of electron relaxation and dephasing rates in quantum dots\n  caused by external magnetic fields: An external magnetic field has been applied in laterally coupled dots (QDs)\nand we have studied the QD properties related to charge decoherence. The\nsignificance of the applied magnetic field to the suppression of\nelectron-phonon relaxation and dephasing rates has been explored. The coupled\nQDs have been studied by varing the magnetic field and the interdot distance as\nother system parameters. Our numerical results show that the electron\nscattering rates are strongly dependent on the applied external magnetic field\nand the details of the double QD configuration.",
        "positive": "Dynamics of the fractional quantum Hall edge probed by stroboscope\n  measurements of trions: By using observations from pump-probe stroboscopic confocal microscopy and\nspectroscopy, we demonstrate the dynamics of trions and the fractional quantum\nHall edge on the order of $\\sim1$ ps. The propagation of the quantum Hall edge\nstate excited by a voltage pulse is detected as a temporal change in\nreflectance in the downstream edge probed by optical pulses synchronized with\nthe voltage pulse. The temporal resolution of such stroboscopic pump-probe\nmeasurements is as fast as the duration time of the probe pulse ($\\sim1$ ps).\nThis ultra-fast stroboscope measurement enables us to distinguish between the\nnormal mode of edge excitation, known as the edge magneto-plasmon or charge\ndensity wave, and other high-energy non-linear excitations. This is the only\nexperimental method available to study the ultra-fast dynamics of quantum Hall\nedges, and makes it possible to derive the metric tensor $g_{\\mu \\nu}$ of the\n$(1+1)=2$-dimensional curved spacetime in quantum universe and black hole\nanalogs implemented in the quantum Hall edge."
    },
    {
        "anchor": "Stabilizing shallow color centers in diamond created by nitrogen\n  delta-doping using SF$_6$ plasma treatment: Here we report the fabrication of stable, shallow (< 5 nm) nitrogen-vacancy\n(NV) centers in diamond by nitrogen delta doping at the last stage of the\nchemical vapor deposition (CVD) growth process. The NVs are stabilized after\ntreating the diamond in $SF_6$ plasma, otherwise the color centers are not\nobserved, suggesting a strong influence from the surface. X-Ray photoelectron\nspectroscopy measurements show the presence of only fluorine atoms on the\nsurface, in contrast to previous studies, and suggests very good surface\ncoverage. We managed to detect hydrogen nuclear magnetic resonance signal from\nprotons in the immersion oil, revealing a depth of the NVs of about 5 nm",
        "positive": "Domain wall formation and magnon localization in twisted chromium\n  trihalides: The rise of twistronics has revolutionized the field of condensed matter\nphysics, and more specifically the future applications of two-dimensional\nmaterials. At small twist angles, the microscopic world becomes strongly\ncorrelated, and unexpected physical phenomena such as superconductivity emerge.\nFor magnetic layers, stacking plays a crucial role in the magnetic exchange\ncoupling between the layers leading to non-trivial spin configurations and flat\nspin-wave dispersion when twisted. In this work, we give a short overview of\nthe most recent theoretical and experimental works reporting the effect of\ntwist angles on two-dimensional magnets. Besides, we discuss the effect of the\ntwist angle and the local antiferromagnetic interlayer exchange coupling on the\nformation of antiferromagnetic domains in chromium trihalides. Finally, we show\nsome preliminary results on the effect of the stacking and the twist angle on\nthe spin-wave dispersion of bilayer CrI$_3$"
    },
    {
        "anchor": "Ultra-shallow quantum dots in an undoped GaAs/AlGaAs 2D electron gas: We report quantum dots fabricated on very shallow 2-dimensional electron\ngases, only 30 nm below the surface, in undoped GaAs/AlGaAs heterostructures\ngrown by molecular beam epitaxy. Due to the absence of dopants, an improvement\nof more than one order of magnitude in mobility (at 2E11 /cm^2) with respect to\ndoped heterostructures with similar depths is observed. These undoped wafers\ncan easily be gated with surface metallic gates patterned by e-beam\nlithography, as demonstrated here from single-level transport through a quantum\ndot showing large charging energies (up to 1.75 meV) and excited state energies\n(up to 0.5 meV).",
        "positive": "Polarization tensor for tilted Dirac fermion materials: Covariance in\n  deformed Minkowski spacetime: The rich structure of solid state physics provides us with Dirac materials\nthe effective theory of which enjoys the Lorentz symmetry. In non-symmorphic\nlattices, the Lorentz symmetry will be deformed in a way that the null\nenergy-momentum vectors will correspond to on-shell condition for tilted Dirac\ncone dispersion. In this sense, tilted Dirac/Weyl materials can be viewed as\nsolid state systems where the effective spacetime is non-Minkowski. In this\nwork, we show that the polarization tensor for tilted Dirac cone systems\nacquires a covariant from only when the spacetime is considered to be an\nappropriate deformation of the Minkowski spacetime. As a unique consequence of\nthe deformation of the geometry of the spacetime felt by the electrons in\ntilted Dirac cone materials, the Coulomb density-density interactions will\ngenerate corrections in both longitudinal and transverse channels. Therefore\nthe transverse photons also participate in mediating the Coulomb forces,\nimplying emergent Amperean forces associated with the tilt of the spacetime."
    },
    {
        "anchor": "A high-$\u03ba$ wide-gap layered dielectric for two-dimensional van der\n  Waals heterostructures: Van der Waals heterostructures of two-dimensional materials have opened up\nnew frontiers in condensed matter physics, unlocking unexplored possibilities\nin electronic and photonic device applications. However, the investigation of\nwide-gap high-$\\kappa$ layered dielectrics for devices based on van der Waals\nstructures has been relatively limited. In this work, we demonstrate an easily\nreproducible synthesis method for the rare earth oxyhalide LaOBr, and we\nexfoliate it as a 2D layered material with a measured static dielectric\nconstant of $\\epsilon_{0, \\perp} \\simeq 9$ and a wide bandgap of 5.3 eV.\nFurthermore, our research demonstrates that LaOBr can be used as a\nhigh-$\\kappa$ dielectric in van der Waals field-effect transistors with high\nperformance and low interface defect concentrations. Additionally, it proves to\nbe an attractive choice for electrical gating in excitonic devices based on 2D\nmaterials. Our work demonstrates the versatile realization and functionality of\n2D systems with wide-gap and high-$\\kappa$ van der Waals dielectric\nenvironments.",
        "positive": "Probing dynamics of an electron-spin ensemble via a superconducting\n  resonator: We study spin relaxation and diffusion in an electron-spin ensemble of\nnitrogen impurities in diamond at low temperature (0.25-1.2 K) and polarizing\nmagnetic field (80-300 mT). Measurements exploit mode- and\ntemperature-dependent coupling of hyperfine-split sub-ensembles to the\nresonator. Temperature-independent spin linewidth and relaxation time suggest\nthat spin diffusion limits spin relaxation. Depolarization of one sub-ensemble\nby resonant pumping of another indicates fast cross-relaxation compared to spin\ndiffusion, with implications on use of sub-ensembles as independent quantum\nmemories."
    },
    {
        "anchor": "Giant Seebeck coefficient in semiconducting single-wall carbon nanotube\n  film: We found a giant Seebeck effect in semiconducting single-wall carbon nanotube\n(SWCNT) films, which exhibited a performance comparable to that of commercial\nBi2Te3 alloys. Carrier doping of semiconducting SWCNT films further improved\nthe thermoelectric performance. These results were reproduced well by\nfirst-principles transport simulations based on a simple SWCNT junction model.\nThese findings suggest strategies that pave the way for emerging printed,\nall-carbon, flexible thermoelectric devices.",
        "positive": "Unconventional Singularity in Anti-Parity-Time Symmetric Cavity\n  Magnonics: By engineering an anti-parity-time (anti-PT) symmetric cavity magnonics\nsystem with precise eigenspace controllability, we observe two different\nsingularities in the same system. One type of singularity, the exceptional\npoint (EP), is produced by tuning the magnon damping. Between two EPs, the\nmaximal coherent superposition of photon and magnon states is robustly\nsustained by the preserved anti-PT symmetry. The other type of singularity,\narising from the dissipative coupling of two anti-resonances, is an\nunconventional bound state in the continuum (BIC). At the settings of BICs, the\ncoupled system exhibits infinite discontinuities in the group delay. We find\nthat both singularities co-exist at the equator of the Bloch sphere, which\nreveals a unique hybrid state that simultaneously exhibits the maximal coherent\nsuperposition and slow light capability."
    },
    {
        "anchor": "Simulating Quantum Spin Hall Effect in Topological Lieb Lattice of\n  Linear Circuit: Inspired by the topological insulator circuit proposed and experimentally\nverified by Jia., et al. \\cite{1}, we theoretically realized the topological\nLieb lattice, a line centered square lattice with rich topological properties,\nin a radio-frequency circuit. We open the topological nontrivial band-gap\nthrough specific capacitor-inductor network, which resembles adding intrinsic\nspin orbit coupling term into the tight binding model. Finally, we discuss the\nextension of the $\\phi=\\pi/2$ phase change of hopping between sites to\narbitrary value, and investigate the topological phase transition of the band\nstructure vary with capacitance, thereby paving the way for designing tunable\nlattices using the presented framework.",
        "positive": "Does a Fermi liquid on a half-filled Landau level have Pomeranchuk\n  instabilities?: We present a theory of spontaneous Fermi surface deformations for half-filled\nLandau levels (filling factors of the form $\\nu=2n+1/2$). We assume the\nhalf-filled level to be in a compressible, Fermi liquid state with a circular\nFermi surface. The Landau level projection is incorporated via a modified\neffective electron-electron interaction and the resulting band structure is\ndescribed within the Hartree-Fock approximation. We regulate the infrared\ndivergences in the theory and probe the intrinsic tendency of the Fermi surface\nto deform through Pomeranchuk instabilities. We find that the corresponding\nsusceptibility never diverges, though the system is asymptotically unstable in\nthe $n \\to \\infty$ limit."
    },
    {
        "anchor": "Manipulating Single Spins in Quantum Dots Coupled to Ferromagnetic Leads: We discuss the possibility to generate, manipulate, and probe single spins in\nsingle-level quantum dots coupled to ferromagnetic leads. The spin-polarized\ncurrents flowing between dot and leads lead to a non-equilibrium spin\naccumulation, i.e., a finite polarization of the dot spin. Both the magnitude\nand the direction of the dot's spin polarization depends on the magnetic\nproperties of leads and their coupling to the dot. They can be, furthermore,\nmanipulated by either an externally applied magnetic field or an intrinsically\npresent exchange field that arises due to the tunnel coupling of the\nstrongly-interacting quantum-dot states to spin-polarized leads. The exchange\nfield can be tuned by both the gate and bias voltage, which, therefore, provide\nconvenient handles to manipulate the quantum-dot spin. Since the transmission\nthrough the quantum-dot spin valve sensitively depends on the state of the\nquantum-dot spin, all the dynamics of the latter is reflected in the transport\nproperties of the device.",
        "positive": "Masses of composite fermions carrying two and four flux quanta:\n  Differences and similarities: This study provides a theoretical rationalization for the intriguing\nexperimental observation regarding the equality of the normalized masses of\ncomposite fermions carrying two and four flux quanta, and also demonstrates\nthat the mass of the latter type of composite fermion has a substantial filling\nfactor dependence in the filling factor range $4/17 > \\nu > 1/5$, in agreement\nwith experiment, originating from the relatively strong inter-composite fermion\ninteractions here."
    },
    {
        "anchor": "Band gaps of primary metallic carbon nanotubes: Primary metallic, or small gap semiconducting nanotubes, are tubes with band\ngaps that arise solely from breaking the bond symmetry due to the curvature. We\nderive an analytic expression for these gaps by considering how a general\nsymmetry breaking opens a gap in nanotubes with a well defined chiral wrapping\nvector. This approach provides a straightforward way to include all types of\nsymmetry breaking effects, resulting in a simple unified gap equation as a\nfunction of chirality and deformations.",
        "positive": "Nodal semimetals in $d\\geq3$ to sharp pseudo-Landau levels by\n  dimensional reduction: Non-uniform strain applied to graphene's honeycomb lattice can induce\npseudo-Landau levels in the single-particle spectrum. Various generalizations\nhave been put forward, including a particular family of hopping models in $d$\nspace dimensions. Here we show that the key ingredient for sharp pseudo-Landau\nlevels in higher dimensions is dimensional reduction. We consider particles\nmoving on a $d$-dimensional hyper-diamond lattice which displays a semimetallic\nbandstructure, with a $(d-2)$-dimensional nodal manifold. By applying a\nsuitable strain pattern, the single-particle spectrum evolves into a sequence\nof relativistic Landau levels. We develop and solve the corresponding field\ntheory: Each nodal point effectively generates a Landau-level problem which is\nstrictly two-dimensional to leading order in the applied strain. While the\neffective pseudo-vector potential varies across the nodal manifold, the\nLandau-level spacing does not. Our theory paves the way to strain engineering\nof single-particle states via dimensional reduction and beyond global minimal\ncoupling."
    },
    {
        "anchor": "Macroscopic quantum effects of electromagnetic induction in silicon\n  nanostructures: At room temperature, a macroscopic quantum galvanomagnetic effect of Faraday\nelectromagnetic induction was demonstrated under conditions of the capture of\nsingle magnetic flux quanta in the edge channels, confined by chains of\nnegative-U centers, in a silicon nanostructure heavily doped with boron,\nprepared in Hall geometry on an n-type Si (100) substrate. It is shown that\nthis effect leads to the appearance of an induction current when only a\nconstant magnetic field is applied in the absence of an externally applied\nvoltage or a stabilized current.",
        "positive": "Spin-polarized tunneling through randomly transparent magnetic\n  junctions: Reentrant magnetoresistance approaching the Julliere limit: Electron conductance in planar magnetic tunnel junctions with long-range\nbarrier disorder is studied within Glauber-eikonal approximation enabling exact\ndisorder ensemble averaging by means of the Holtsmark-Markov method. This\nallows us to address a hitherto unexplored regime of the tunneling\nmagnetoresistance effect characterized by the crossover from\nmomentum-conserving to random tunneling as a function of the defect\nconcentration. We demonstrate that such a crossover results in a reentrant\nmagnetoresistance: It goes through a pronounced minimum before reaching\ndisorder- and geometry-independent Julliere's value at high defect\nconcentrations."
    },
    {
        "anchor": "Na-intercalation compounds and Na-ion batteries: The widely use of lithium-ion (Li-ion) batteries in various fields, from\nportable products to large-scale energy storage systems, has revolutionized our\ndaily life. The 2019 Nobel Prize in Chemistry has been awarded to John B.\nGoodenough, M. Stanley Whittingham, and Akira Yoshino for their contributions\nin developing Li-ion batteries. Although Li-ion batteries are currently\non-growing research topics, lithium availability is still a problem for mass\nproduction. In contrast to lithium, sodium resources are almost unlimited on\nEarth, and sodium is one of the most abundant elements in the Earth's crust.\nHence, sodium-ion (Na-ion) batteries as a counterpart of Li-ion batteries have\nthe potential to serve as the next-generation batteries. In this work, a brief\nhistory and recent development of Na-ion batteries are described. The\nfundamental physical and electronic properties, such as geometric structures,\nband structure, density of states, and spatial charge distributions, of\nNa-intercalation compounds are discussed. The outlook of Na-ion batteries is\ngiven at the last.",
        "positive": "Topological States and Adiabatic Pumping in Quasicrystals: The unrelated discoveries of quasicrystals and topological insulators have in\nturn challenged prevailing paradigms in condensed-matter physics. We find a\nsurprising connection between quasicrystals and topological phases of matter:\n(i) quasicrystals exhibit nontrivial topological properties and (ii) these\nproperties are attributed to dimensions higher than that of the quasicrystal.\nSpecifically, we show, both theoretically and experimentally, that\none-dimensional quasicrystals are assigned two-dimensional Chern numbers and,\nrespectively, exhibit topologically protected boundary states equivalent to the\nedge states of a two-dimensional quantum Hall system.We harness the topological\nnature of these states to adiabatically pump light across the quasicrystal. We\ngeneralize our results to higher-dimensional systems and other topological\nindices. Hence, quasicrystals offer a new platform for the study of topological\nphases while their topology may better explain their surface properties."
    },
    {
        "anchor": "Strong interlayer coupling and stable topological flat bands in twisted\n  bilayer photonic Moire superlattices: The moir\\'e superlattice of misaligned atomic bilayers paves the way for\ndesigning a new class of materials with wide tunability. In this work, we\npropose a photonic analog of the moir\\'e superlattice based on dielectric\nresonator quasi-atoms. In sharp contrast to van der Waals materials with weak\ninterlayer coupling, we realize the strong coupling regime in a moir\\'e\nsuperlattice, characterized by cascades of robust flat bands at large\ntwist-angles. Surprisingly, we find that these flat bands are characterized by\na non-trivial band topology, the origin of which is the moir\\'e pattern of the\nresonator arrangement. The physical manifestation of the flat band topology is\na robust one-dimensional conducting channel on edge, protected by the\nreflection symmetry of the moir\\'e superlattice. By explicitly breaking the\nunderlying reflection symmetry on the boundary terminations, we show that the\nfirst-order topological edge modes naturally deform into higher-order\ntopological corner modes. Our work pioneers the physics of topological phases\nin the designable platform of photonic moir\\'e superlattices beyond the weakly\ncoupled regime.",
        "positive": "Tunable thermoelectricity in monolayers of MoS$_{2}$ and other group-VI\n  dichalcogenides: We study the thermoelectric properties of monolayers of MoS$_{2}$ and other\ngroup-VI dichalcogenides under circularly polarized off-resonant light.\nAnalytical expressions are derived for the Berry phase mediated magnetic\nmoment, orbital magnetization, as well as thermal and Nernst conductivities.\nTuning of the band gap by {\\it off-resonant} light enhances the spin splitting\nin both the valence and conduction bands and, thus, leads to a dramatic\nimprovement of the spin and valley thermoelectric properties."
    },
    {
        "anchor": "Manipulation and steering of hyperbolic surface polaritons in hexagonal\n  boron nitride: Hexagonal boron nitride (hBN) is a natural hyperbolic material that supports\nboth volume-confined hyperbolic polaritons (HPs) and sidewall-confined\nhyperbolic surface polaritons (HSPs). In this work, we demonstrate effective\nexcitation, control and steering of HSPs in hBN through engineering the\ngeometry and orientation of hBN sidewalls. By combining infrared (IR)\nnano-imaging and numerical simulations, we investigate the reflection,\ntransmission and scattering of HSPs at the hBN corners with various apex\nangles. We show that the sidewall-confined nature of HSPs enables a high degree\nof control over their propagation by designing the geometry of hBN\nnanostructures.",
        "positive": "The excitonic resonance in semiconductor-metal nano-hybrids: We use a configuration interaction approach within the envelope function\napproximation to study the nature of the excitonic resonance in nano-hybrids,\ncomposite nanoparticles (NPs) combining a semiconducting and a metallic segment\nin contact. With reference to recent experimental reports, we specifically\nstudy CdS-based nanorods with metallic NPs deposited at the tips (matchstick)\nor metallic coatings (core-shell). The excitonic states are computed taking\ninto account both the renormalization of the electron-hole interaction and\nself-energy effects induced by the the metallic segment on the electron-hole\npair, as well as by the dielectric environment, through an induced charge\nnumerical approach. In neutral matchstick structures the metal NP has only a\nminor influence (~1 meV) on the excitonic states. When the metallic NP is\ncharged the exciton becomes rapidly redshifted and spatially indirect. In\ncontrast, in neutral core-shell structures the exciton energy redshifts by tens\nof meV"
    },
    {
        "anchor": "Design of a room-temperature topological exciton-polariton laser in a\n  ZnO/TiO$_2$-photonic crystal slab: We propose theoretically a scheme to get a room-temperature 2D topological\nexciton-polariton laser with propagating topological lasing modes. The\nstructure uses guided modes in a photonic crystal slab. A ZnO layer provides\nstrong excitonic resonances stable at room temperature. It is capped by a\nTiO$_2$ layer pierced by a triangular lattice. The exciton-polariton modes of\nthe 3D structure are computed by solving numerically Maxwell's equations\nincluding the excitonic response. The designed triangular lattice shows a\ntransverse electric gap. The triangular lattice is shown to be the limit of a\nstaggered honeycomb lattice when one of the sub-lattices vanishes. Its topology\ncan be characterized by symmetry indicators. The interface between two shifted\ntriangular lattices supports two counter-propagating modes lying in the gap of\nthe bulk modes. The interface states are analogous to quantum pseudospin Hall\ninterface states. These modes show orthogonal polarizations. They can be\nselectively excited using polarized excitation and are well-protected from\nback-scattering. These modes can benefit from the exciton-polariton gain at\nroom temperature because of their sufficiently large exciton fraction and\nfavorable position in energy. The strong localization of these propagating\nmodes makes them suitable to host topological lasing triggered by a\nnon-resonant pump localized on the interface.",
        "positive": "Heat, particle and chiral currents in a boundary driven bosonic ladders\n  in presence of gauge fields: Quantum systems can undergo phase transitions and show distinct features in\ndifferent phases. The corresponding transport properties can also vary\nsignificantly due to the underlying quantum phase. We investigate the transport\nbehaviour of a two-legged bosonic ladder in a uniform gauge field, which is\nknown to have a Meissner-like phase and a vortex phase in the absence of\ndissipation. The ladder is coupled to bosonic baths at different temperatures,\nand we study it using the non-equilibrium Green's function method. In\nparticular, we show the presence of a chiral current and how it is affected by\nthe temperature bias and the dissipation strength. We also demonstrate that the\nopening of a gap between the lower and upper energy band results in the\npossibility of tuning heat and particle transport through the ladder. We show\nthat for system parameters for which the ground state is in a vortex phase, the\nsystem is more sensitive to external perturbations."
    },
    {
        "anchor": "Jump of tunneling magnetoresistance in magnetic nanocontacts with\n  mismatched cross section: We have studied the influence of the transverse size of a magnetic tunnel\nnanojunction on the magnitude of the magnetoresistance. During modeling, the\nsize of the right contact was fixed, while the size of the left one gradually\nchanged until they coincided. We found a sharp drop in the tunneling\nmagnetoresistance (TMR) in nanocontacts with mismatched cross section. This can\nbe explained by the peculiarities of the spatial distribution of the electron\ndensity, which is different for majority and minority-spin states. The\ndiscovered effect must be taken into account in the design of TMR-based\nnanodevices.",
        "positive": "Two Types of 3D Quantum Hall Effects in Multilayer WTe$_2$: Interplay between the topological surface states and bulk states gives rise\nto diverse exotic transport phenomena in topological materials. The recently\nproposed Weyl orbit in topological semimetals in the presence of magnetic field\nis a remarkable example. This novel closed magnetic orbit consists of Fermi\narcs on two spatially separated sample surfaces which are connected by the bulk\nchiral zero mode, which can contribute to transport. Here we report\nShubnikov-de Haas (SdH) oscillation and its evolution into quantum Hall effect\n(QHE) in multilayered type-II Weyl semimetal WTe2. We observe both the\nthree-dimensional (3D) QHE from bulk states by parallelly stacking of confined\ntwo-dimensional layers in the low magnetic field region and the 3D QHE in the\nquantized surface transport due to Weyl orbits in the high magnetic field\nregion. Our study of the two types of novel QHEs controlled by magnetic field\nand our demonstration of the crossover between quantized bulk and surface\ntransport provide an essential platform for the future quantized transport\nstudies in topological semimetals."
    },
    {
        "anchor": "Reaction matrix for Dirichlet billiards with attached waveguides: The reaction matrix of a cavity with attached waveguides connects scattering\nproperties to properties of a corresponding closed billiard for which the\nwaveguides are cut off by straight walls. On the one hand this matrix is\ndirectly related to the S-matrix, on the other hand it can be expressed by a\nspectral sum over all eigenfunctions of the closed system. However, in the\nphysically relevant situation where these eigenfunctions vanish on the\nimpenetrable boundaries of the closed billiard, the spectral sum for the\nreaction matrix, as it was used before, fails to converge and does not reliably\nreproduce the scattering properties. We derive here a convergent representation\nof the reaction matrix in terms of eigenmodes satisfying Dirichlet boundary\nconditions and demonstrate its validity in the rectangular and the Sinai\nbilliards.",
        "positive": "Coherent optical manipulation of triplet-singlet states in coupled\n  quantum dots: We show that spin-orbit coupling in a quantum dot molecule allows for\ncoherent manipulation of two electron spin states using Raman transitions. Such\ntwo-electron spin states defined by the singlet and triplet states of two\nexchange coupled quantum dots can have favorable coherence properties. In\naddition, two of the four metastable ground states in this system can be used\nas auxiliary states that could facilitate implementation of tasks such as\nmapping of spin states to that of a single propagating photon. We find that\neven weak spin-orbit effects -- manifesting themselves as slightly different\ng-factors for the electron and the hole -- would allow for the coherent Raman\ncoupling of the singlet-triplet states. We also discuss the possibilities for\nimplementing quantum optical techniques for spin preparation and manipulation."
    },
    {
        "anchor": "Architecting three-dimensional ZnO nanorods: The fabrication of nanostructures with controlled assembly and architecture\nis significant for the development of novel nanomaterials-based devices. In\nthis work we demonstrate that laser techniques coupled with low-temperature\nhydrothermal growth enable complex three-dimensional ZnO nanorods patterning on\nvarious types of substrates and geometries. The suggested methodology is based\non a procedure involving the 3D scaffold fabrication using Multi-Photon\nLithography of a photosensitive material, followed by Zn seeded Aqueous\nChemical Growth of ZnO nanorods. 3D, uniformly aligned ZnO nanorods are\nproduced, exhibiting electrical conductance and highly efficient photocatalytic\nperformance, providing a path to applications in a diverse field of\ntechnologies.",
        "positive": "Resonant generation of propagating second-harmonic spin waves in\n  nano-waveguides: Generation of second-harmonic waves is one of the universal nonlinear\nphenomena that have found numerous technical applications in many modern\ntechnologies, in particular, in photonics. This phenomenon also has great\npotential in the field of magnonics, which considers the use of spin waves in\nmagnetic nanostructures to implement wave-based signal processing and\ncomputing. However, due to the strong frequency dependence of the phase\nvelocity of spin waves, resonant phase-matched generation of second-harmonic\nspin waves has not yet been achieved in practice. Here, we show experimentally\nthat such a process can be realized using a combination of different modes of\nnano-sized spin-wave waveguides based on low-damping magnetic insulators. We\ndemonstrate that our approach enables efficient spatially-extended energy\ntransfer between interacting waves, which can be controlled by the intensity of\nthe initial wave and the static magnetic field. The demonstrated approach can\nbe used for the generation of short-wavelength spin waves that are difficult to\nexcite directly, as well as for the implementation of novel devices for\nmagnonic logic and unconventional computing."
    },
    {
        "anchor": "Excitonic Resonances in Coherent Anti-Stokes Raman Scattering from\n  Single Wall Carbon Nanotubes: In this work we investigate the role of exciton resonances in coherent\nanti-Stokes Raman scattering (er-CARS) in single walled carbon nanotubes\n(SWCNTs). We drive the nanotube system in simultaneous phonon and excitonic\nresonances, where we observe a superior enhancement by orders of magnitude\nexceeding non-resonant cases. We investigated the resonant effects in five\n$(n,m)$ chiralities and find that the er-CARS intensity varies drastically\nbetween different nanotube species. The experimental results are compared with\na perturbation theory model. Finally, we show that such giant resonant\nnon-linear signals enable rapid mapping and local heating of individualized\nCNTs, suggesting easy tracking of CNTs for future nanotoxology studies and\ntherapeutic application in biological tissues.",
        "positive": "Quantized transport in topological insulator n-p-n junctions: Electrical transport in three dimensional topological insulators(TIs) occurs\nthrough spin-momentum locked topological surface states that enclose an\ninsulating bulk. In the presence of a magnetic field, surface states get\nquantized into Landau levels giving rise to chiral edge states that are\nnaturally spin-polarized due to spin momentum locking. It has been proposed\nthat p-n junctions of TIs in the quantum Hall regime can manifest unique spin\ndependent effects, apart from forming basic building blocks for highly\nfunctional spintronic devices. Here, for the first time we study\nelectrostatically defined n-p-n junctions of bulk insulating topological\ninsulator BiSbTe$_{1.25}$Se$_{1.75}$ in the quantum Hall regime. We reveal the\nremarkable quantization of longitudinal resistance into plateaus at 3/2 and 2/3\nh/e$^2$, apart from several partially developed fractional plateaus.\nTheoretical modeling combining the electrostatics of the dual gated TI n-p-n\njunction with Landauer Buttiker formalism for transport through a network of\nchiral edge states explains our experimental data, while revealing remarkable\ndifferences from p-n junctions of graphene and two-dimensional electron gas\nsystems. Our work not only opens up a route towards exotic spintronic devices\nbut also provides a test bed for investigating the unique signatures of quantum\nHall effects in topological insulators."
    },
    {
        "anchor": "Flux-quantum-modulated Kondo conductance in a multielectron quantum dot: We investigate a lateral semiconductor quantum dot with a large number of\nelectrons in the limit of strong coupling to the leads. A Kondo effect is\nobserved and can be tuned in a perpendicular magnetic field. This Kondo effect\ndoes not exhibit Zeeman splitting. It shows a modulation with the periodicity\nof one flux quantum per dot area at low temperatures. The modulation leads to a\nnovel, strikingly regular stripe pattern for a wide range in magnetic field and\nnumber of electrons.",
        "positive": "Effective Interactions in a Graphene Layer Induced by the Proximity to a\n  Ferromagnet: The proximity-induced couplings in graphene due to the vicinity of a\nferromagnetic insulator are analyzed. We combine general symmetry principles\nand simple tight-binding descriptions to consider different orientations of the\nmagnetization. We find that, in addition to a simple exchange field, a number\nof other terms arise. Some of these terms act as magnetic orbital couplings,\nand others are proximity-induced spin-orbit interactions. The couplings are of\nsimilar order of magnitude, and depend on the orientation of the magnetization.\nA variety of phases, and anomalous Hall effect regimes, are possible."
    },
    {
        "anchor": "Engineering elliptical spin-excitations by complex anisotropy fields in\n  Fe adatoms and dimers on Cu(111): We investigate the dynamics of Fe adatoms and dimers deposited on the Cu(111)\nmetallic surface in the presence of spin-orbit coupling, within time-dependent\ndensity functional theory. The \\textit{ab initio} results provide\nmaterial-dependent parameters that can be used in semiclassical approaches,\nwhich are used for insightful interpretations of the excitation modes. By\nmanipulating the surroundings of the magnetic elements, we show that elliptical\nprecessional motion may be induced through the modification of the magnetic\nanisotropy energy. We also demonstrate how different kinds of spin precession\nare realized, considering the symmetry of the magnetic anisotropy energy, the\nferro- or antiferromagnetic nature of the exchange coupling between the\nimpurities, and the strength of the magnetic damping. In particular, the normal\nmodes of a dimer depend on the initial magnetic configuration, changing\ndrastically by going from a ferromagnetic metastable state to the\nantiferromagnetic ground state. By taking into account the effect of the\ndamping into their resonant frequencies, we reveal that an important\ncontribution arises for strongly biaxial systems and specially for the\nantiferromagnetic dimers with large exchange couplings. Counter intuitively,\nour results indicate that the magnetic damping influences the quantum\nfluctuations by decreasing the zero-point energy of the system.",
        "positive": "Casimir pressure in peptide films on metallic substrates: Change of sign\n  via graphene coating: We find that the Casimir pressure in peptide films deposited on metallic\nsubstrates is always repulsive which makes these films less stable. It is shown\nthat by adding a graphene sheet on top of peptide film one can change the sign\nof the Casimir pressure by making it attractive. For this purpose, the\nformalism of the Lifshitz theory is extended to the case when the film and\nsubstrate materials are described by the frequency-dependent dielectric\npermittivities, whereas the response of graphene to the electromagnetic field\nis governed by the polarization tensor in (2+1)-dimensional space-time found in\nthe framework of the Dirac model. Both pristine and gapped and doped graphene\nsheets are considered possessing some nonzero energy gap and chemical\npotential. According to our results, in all cases the presence of graphene\nsheet makes the Casimir pressure in peptide film deposited on a metallic\nsubstrate attractive starting from some minimum film thickness. The value of\nthis minimum thickness becomes smaller with increasing chemical potential and\nlarger with increasing energy gap and the fraction of water in peptide film.\nThe physical explanation for these results is provided, and their possible\napplications in organic electronics are discussed."
    },
    {
        "anchor": "Single Spin Localization and Manipulation in Graphene Open-Shell\n  Nanostructures: Predictions state that graphene can spontaneously develop magnetism from the\nCoulomb repulsion of its $\\pi$-electrons, but its experimental verification has\nbeen a challenge. Here, we report on the observation and manipulation of\nindividual magnetic moments localized in graphene nanostructures on a Au(111)\nsurface. Using scanning tunneling spectroscopy, we detected the presence of\nsingle electron spins localized around certain zigzag sites of the carbon\nbackbone via the Kondo effect. Two near-by spins were found coupled into a\nsinglet ground state, and the strength of their exchange interaction was\nmeasured via singlet-triplet inelastic tunnel electron excitations. Theoretical\nsimulations demonstrate that electron correlations result in spin-polarized\nradical states with the experimentally observed spatial distributions. Hydrogen\natoms bound to these radical sites quench their magnetic moment, permitting us\nto switch the spin of the nanostructure using the tip of the microscope.",
        "positive": "SET Backaction on the Single Electron Box: We report an experimental observation of the backaction of a Single Electron\nTransistor (SET) measuring the Coulomb staircase of a single electron box. As\ncurrent flows through the SET, the charge state of the SET island fluctuates.\nThese fluctuations capacitively couple to the box and cause changes in the\nposition, width, and asymmetry of the Coulomb staircase. A sequential\ntunnelling model accurately recreates these effects, confirming this mechanism\nof the backaction of an SET. This is a first step towards understanding the\neffects of quantum measurement on solid state qubits."
    },
    {
        "anchor": "Vector Pulsing Solitons in Semiconductor Quantum Dots: A theory of an optical vector pulsing soliton of self-induced transparency in\nan ensemble of semiconductor quantum dots is investigated. It is shown that a\ndistribution of the excitonic ground-state transition dipole moments of the\nquantum dots and phase modulation changes significantly the pulse parameters.\nThe profile of a circularly polarized optical two-component vector pulsing\nsoliton with the difference and sum of the frequencies in the region of the\ncarrier frequency is presented. It is shown that the vector pulsing soliton in\nthe special case can be reduced to the scalar breather solution and these\nnonlinear waves have different shapes. Explicit analytical expressions for the\noptical vector pulsing soliton are obtained with realistic parameters which can\nbe reached in current experiments.",
        "positive": "Fast spin rotations by optically controlled geometric phases in a\n  quantum dot: We demonstrate optical control of the geometric phase acquired by one of the\nspin states of an electron confined in a charge-tunable InAs quantum dot via\ncyclic 2pi excitations of an optical transition in the dot. In the presence of\na constant in-plane magnetic field, these optically induced geometric phases\nresult in the effective rotation of the spin about the magnetic field axis and\nmanifest as phase shifts in the spin quantum beat signal generated by two\ntime-delayed circularly polarized optical pulses. The geometric phases\ngenerated in this manner more generally perform the role of a spin phase gate,\nproving potentially useful for quantum information applications."
    },
    {
        "anchor": "Fermi-Edge Resonance and Tunneling in Nonequilibrium Electron Gas: Fermi-edge singularity changes in a dramatic way in a nonequilibrium system,\nacquiring features which reflect the structure of energy distribution. In\nparticular, it splits into several components if the energy distribution\nexhibits multiple steps. While conventional approaches, such as bosonization,\nfail to describe the nonequilibrium problem, an exact solution for a generic\nenergy distribution can be obtained with the help of the method of functional\ndeterminants. In the case of a split Fermi distribution, while the `open loop'\ncontribution to Green's function has power law singularities, the tunneling\ndensity of states profile exhibits broadened peaks centered at Fermi\nsub-levels.",
        "positive": "Resonant optical topological Hall conductivity from skyrmions: We study the high frequency Hall conductivity in a two-dimensional (2D) model\nof conduction electrons coupled to a background magnetic skyrmion texture via\nan effective Hund's coupling term. For an ordered skyrmion crystal, a Kubo\nformula calculation using the basis of skyrmion crystal Chern bands reveals a\nresonant Hall response at a frequency set by the Hund's coupling:\n$\\hbar\\omega_{\\text{res}} \\approx J_H$. A complementary real-space Kubo formula\ncalculation for an isolated skyrmion in a box reveals a similar resonant Hall\nresponse. A linear relation between the area under the Hall resonant curve and\nthe skyrmion density is discovered numerically and is further elucidated using\na gradient expansion which is valid for smooth textures and a local\napproximation based on a spin-trimer calculation. We point out the issue of\ndistinguishing this skyrmion contribution from a similar feature arising from\nspin-orbit interactions, as demonstrated in a model for Rashba spin-orbit\ncoupled electrons in a collinear ferromagnet, which is analogous to the\ndifficulty of unambiguously separating the d.c. topological Hall effect from\nthe anomalous Hall effect. The resonant feature in the high frequency\ntopological Hall effect is proposed to provide a potentially useful local\noptical signature of skyrmions via probes such as scanning magneto-optical Kerr\nmicroscopy."
    },
    {
        "anchor": "Measurement of Collective Dynamical Mass of Dirac Fermions in Graphene: Individual electrons in graphene behave as massless quasiparticles. In\nsurprising twist, it is inferred from plasmonic investigations that\ncollectively excited graphene electrons must exhibit non-zero mass and its\ninertial acceleration is essential for graphene plasmonics. Despite such\nimportance, this collective mass has defied direct unequivocal measurement. It\nmay be directly measured by accelerating it with a time-varying voltage and\nquantifying the phase delay of the resulting current; this voltage-current\nphase relation would manifest as kinetic inductance, representing the\ncollective inertia's reluctance to accelerate. However, at optical (infrared)\nfrequencies phase measurement of current is generally difficult and at\nmicrowave frequencies the inertial phase delay has been buried under electron\nscattering. Here we directly, precisely measure the kinetic inductance, thus,\ncollective mass, by combining innovative device engineering that reduces\nelectron scattering and delicate microwave phase measurements. Particularly,\nencapsulation of graphene between hexagonal-boron-nitride layers,\none-dimensional edge contacts, and a proximate top gate configured as microwave\nground together enable resolving the inertial phase delay from the electron\nscattering. Beside the fundamental importance, the kinetic inductance\ndemonstrated here to be orders-of-magnitude larger than magnetic inductance can\ndramatically miniaturize radio-frequency integrated circuits. Moreover, its\nbias-dependency heralds a solid-state voltage-controlled inductor to complement\nthe prevalent voltage-controlled capacitor.",
        "positive": "Universality of low-energy Rashba scattering: We investigate the scattering of a quantum particle with a two-dimensional\n(2D) Rashba spin-orbit coupled dispersion off of circularly symmetric\npotentials. As the energy of the particle approaches the bottom of the lowest\nspin-split band, i.e., the van Hove singularity, earlier work has shown that\nscattering off of an infinite circular barrier exhibits a number of features\nunusual from the point of view of conventional 2D scattering theory: the\nlow-energy S-matrix is independent of the range of the potential, all partial\nwaves contribute equally, the differential cross section becomes increasingly\nanisotropic and 1D-like, and the total cross section exhibits quantized\nplateaus. Via a nonperturbative determination of the T-matrix and an optical\ntheorem which we prove here, we show that this behavior is universal for Rashba\nscattering off of any circularly symmetric, spin independent, finite-range\npotential. This is relevant both for impurity scattering in the noninteracting\nlimit as well as for short-range two-particle scattering in the interacting\nproblem."
    },
    {
        "anchor": "Sub-10 nm colloidal lithography for integrated spin-photo-electronic\n  devices: Colloidal lithography [1] is how patterns are reproduced in a variety of\nnatural systems and is used more and more as an efficient fabrication tool in\nbio-, opto-, and nano-technology. Nanoparticles in the colloid are made to form\na mask on a given material surface, which can then be transferred via etching\ninto nano-structures of various sizes, shapes, and patterns [2,3]. Such\nnanostructures can be used in biology for detecting proteins [4] and DNA [5,6],\nfor producing artificial crystals in photonics [7,8] and GHz oscillators in\nspin-electronics [9-14]. Scaling of colloidal patterning down to 10-nm and\nbelow, dimensions comparable or smaller than the main relaxation lengths in the\nrelevant materials, including metals, is expected to enable a variety of new\nballistic transport and photonic devices, such as spin-flip THz lasers [15]. In\nthis work we extend the practice of colloidal lithography to producing\nlarge-area, near-ballistic-injection, sub-10 nm point-contact arrays and\ndemonstrate their integration in to spin-photo-electronic devices.",
        "positive": "Current-driven Rashba Field in a Magnetic Quantum Well: In materials lacking inversion symmetry, the spin-orbit coupling enables the\ndirect connection between the electron's spin and its linear momentum, a\nphenomenon called inverse spin galvanic effect. In magnetic materials, this\neffect promotes current-driven torques that can be used to control the\nmagnetization direction electrically. In this work, we investigate the\ncurrent-driven inverse spin galvanic effect in a quantum well consisting in a\nmagnetic material embedded between dissimilar insulators. Assuming the presence\nof Rashba spin-orbit coupling at the interfaces, we investigate the nature of\nthe non-equilibrium spin density and the influence of the quantum well\nparameters. We find that the torque is governed by the interplay between the\nnumber of states participating to the transport and their spin chirality, the\npenetration of the wave function into the tunnel barriers, and the strength of\nthe Rashba term."
    },
    {
        "anchor": "Ferrimagnetic nanostructures for magnetic memory bits: Increasing the magnetic data recording density requires reducing the size of\nthe individual memory elements of a recording layer as well as employing\nmagnetic materials with temperature-dependent functionalities. Therefore, it is\npredicted that the near future of magnetic data storage technology involves a\ncombination of energy-assisted recording on nanometer-scale magnetic media. We\npresent the potential of heat-assisted magnetic recording on a patterned\nsample; a ferrimagnetic alloy composed of a rare earth and a transition metal,\nDyCo$_5$, which is grown on a hexagonal-ordered nanohole array membrane. The\nmagnetization of the antidot array sample is out-of-plane oriented at room\ntemperature and rotates towards in-plane upon heating above its\nspin-reorientation temperature (T$_R$) of ~350 K, just above room temperature.\nUpon cooling back to room temperature (below T$_R$), we observe a well-defined\nand unexpected in-plane magnetic domain configuration modulating with ~45 nm.\nWe discuss the underlying mechanisms giving rise to this behavior by comparing\nthe magnetic properties of the patterned sample with the ones of its extended\nthin film counterpart. Our results pave the way for novel applications of\nferrimagnetic antidot arrays of superior functionality in magnetic nano-devices\nnear room temperature.",
        "positive": "Detect Axial Gauge Fields with a Calorimeter: Torsional strain in Weyl semimetals excites a unidirectional chiral density\nwave propagating in the direction of the torsional vector. This gapless\nexcitation, named the chiral sound wave, is generated by a particular\nrealization of the axial anomaly via the triple-axial (AAA) anomalous diagram.\nWe show that the presence of the torsion-generated chiral sound leads to a\nlinear behavior of the specific heat of a Weyl semimetal and to an enhancement\nof the thermal conductivty at experimentally accessible temperatures. We also\ndemonstrate that such an elastic twist lowers the temperature of the sample,\nthus generating a new, anomalous type of elasto-calorific effect. Measurements\nof these thermodynamical effects will provide experimental verification of the\nexotic triple-axial anomaly as well as the reality of the elastic\npseudomagnetic fields in Weyl semimetals."
    },
    {
        "anchor": "Heavy hole states in Germanium hut wires: Hole spins have gained considerable interest in the past few years due to\ntheir potential for fast electrically controlled qubits. Here, we study holes\nconfined in Ge hut wires, a so far unexplored type of nanostructure. Low\ntemperature magnetotransport measurements reveal a large anisotropy between the\nin-plane and out-of-plane g-factors of up to 18. Numerical simulations verify\nthat this large anisotropy originates from a confined wave function which is of\nheavy hole character. A light hole admixture of less than 1% is estimated for\nthe states of lowest energy, leading to a surprisingly large reduction of the\nout-of-plane g-factors. However, this tiny light hole contribution does not\ninfluence the spin lifetimes, which are expected to be very long, even in non\nisotopically purified samples.",
        "positive": "Interface-induced Topological Insulator Transition in GaAs/Ge/GaAs\n  Quantum Wells: We demonstrate theoretically that interface engineering can drive Germanium,\none of the most commonly-used semiconductors, into topological insulating\nphase. Utilizing giant electric fields generated by charge accumulation at\nGaAs/Ge/GaAs opposite semiconductor interfaces and band folding, the new design\ncan reduce the sizable gap in Ge and induce large spin-orbit interaction, which\nlead to a topological insulator transition. Our work provides a new method on\nrealizing TI in commonly-used semiconductors and suggests a promising approach\nto integrate it in well developed semiconductor electronic devices."
    },
    {
        "anchor": "Dirac plasmon polaritons and magnetic modes in topological-insulator\n  nanoparticles: We report the existence of previously unreported magnetic modes with\nrecord-high magnetic Purcell factors in topological-insulator nanospheres.\nFocusing on Bi$_{2}$Se$_{3}$, and based on full electromagnetic Mie theory, we\nfind magnetic modes arising from the surface current on the conductive surface\nof the topological insulator due to the existence of delocalized surface\nstates. These currents are induced by electrons in the topologically protected\nstates within the Dirac cone. Furthermore, we demonstrate that the Dirac\nplasmon polaritons resulting from the interaction between THz photons and Dirac\nelectrons dramatically influence both the electric and the magnetic transitions\nof quantum emitters placed near Bi$_2$Se$_3$ nanospheres, providing\nsignificantly enhanced Purcell factors and entering the strong-coupling regime.\nThese findings indicate that Bi$_{2}$Se$_{3}$ nanospheres exhibit a rich\noptical response, stemming from both bulk and topologically protected surface\nstates, making them promising candidates for enhancing strong light--matter\ninteractions in the fields of nanophotonics and THz technologies.",
        "positive": "Long electron dephasing length and disorder-induced spin-orbit coupling\n  in indium tin oxide nanowires: We have measured the quantum-interference magnetoresistances in two single\nindium tin oxide (ITO) nanowires between 0.25 and 40 K, by using the four-probe\nconfiguration method. The magnetoresistances are compared with the\none-dimensional weak-(anti)localization theory to extract the electron\ndephasing length $L_\\phi$. We found, in a 60-nm diameter nanowire with a low\nresistivity of $\\rho$(10 K) = 185 $\\mu \\Omega$ cm, that $L_\\phi$ is long,\nincreasing from 150 nm at 40 K to 520 nm at 0.25 K. Therefore, the nanowire\nreveals strict one-dimensional weak-localization effect up to several tens of\ndegrees of Kelvin. In a second 72-nm diameter nanowire with a high resistivity\nof $\\rho$(10 K) = 1030 $\\mu \\Omega$ cm, the dephasing length is suppressed to\n$L_\\phi$(0.26 K) = 200 nm, and thus a crossover of the effective device\ndimensionality from one to three occurs at about 12 K. In particular,\ndisorder-induced spin-orbit coupling is evident in the latter sample,\nmanifesting weak-antilocalization effect at temperatures below $\\sim$ 4 K.\nThese observations demonstrate that versatile quantum-interference effects can\nbe realized in ITO nanowires by controlling differing levels of atomic defects\nand impurities."
    },
    {
        "anchor": "Heavy and Light Monopoles in Magnetic Reversion in Artificial Spin Ice: This work makes a theoretical study of the dynamics of emergent elemental\nexcitations in artificial spin ice systems with hexagonal geometry during the\nmagnetic reversion of the system. The magnetic and physical parameters of the\nnanoislands that form the array are considered as variables in the study. The\nparameters considered are: the energy barrier for the inversion of each\nnanoisland, the magnetic moment of the nanomagnets and the possible disorder in\nthe sample. Our results show that the reversion dynamic presents two distinct\nmechanisms of magnetic reversion, with different elemental excitations for each\nmechanism. The first mechanism presents a reversion with the appearance of\nmagnetic monopoles that do not move in the samples (heavy monopoles) and the\nabsence of Dirac chains. In the other mechanism elemental magnetic excitations\n(light monopoles) appear that move great distances in the sample, giving rise\nto extensive Dirac chains during the magnetic reversion.",
        "positive": "Interlayer tunneling in counterflow experiments on the excitonic\n  condensate in quantum Hall bilayers: The effect of tunneling on the transport properties of} quantum Hall double\nlayers in the regime of the excitonic condensate at total filling factor one is\nstudied in counterflow experiments. If the tunnel current $I$ is smaller than a\ncritical $I_C$, tunneling is large and is effectively shorting the two layers.\nFor $I > I_C$ tunneling becomes negligible. Surprisingly, the transition\nbetween the two tunneling regimes has only a minor impact on the features of\nthe filling-factor one state as observed in magneto-transport, but at currents\nexceeding $I_C$ the resistance along the layers increases rapidly."
    },
    {
        "anchor": "How perfect can graphene be?: Fabrication of graphene structures has triggered vast research efforts\nfocused on the properties of two-dimensional systems with massless Dirac\nfermions. Nevertheless, further progress in exploring this quantum\nelectrodynamics system in solid-state laboratories seems to be limited by\ninsufficient electronic quality of manmade structures and the crucial question\narises whether existing technologies have reached their limits or major\nadvances are in principle possible. Here we show that graphene in a\nsignificantly purer state can be found in nature on the surface of bulk\ngraphite, in form of flakes decoupled from the substrate material. Probing such\nflakes with Landau level spectroscopy in the THz range at very low magnetic\nfields, we demonstrate a superior electronic quality of these ultra low density\nlayers (n~3x10^9 cm^-2) expressed by the carrier mobility in excess of 10^7\ncm^2/(V.s). This finding represents an important challenge for further\nimprovements of current graphene technologies.",
        "positive": "Photoconversion of shallow nitrogen-vacancy centers in flat and\n  nanostructured diamond under high-power laser irradiation: Shallow, negatively-charged Nitrogen-Vacancy centers (NV-) in diamond have\nbeen proposed for high-sensitivity magnetometry and spin-polarization transfer\napplications. However, surface effects tend to favor and stabilize the less\nuseful neutral form, the NV0 centers. Here, we report the effects of green\nlaser irradiation on ensembles of nanometer-shallow NV centers in flat and\nnanostructured diamond surfaces as a function of laser power in a range not\npreviously explored (up to 150 mW/{\\mu}m2). Raman spectroscopy,\noptically-detected-magnetic-resonance (ODMR) and charge-photoconversion\nfluorescence detection are applied to characterize the properties and dynamics\nof NV- and NV0 centers. We demonstrate that high laser power strongly promotes\nphotoconversion of NV0 to NV- centers. Surprisingly, the excess NV- population\nis stable over a time scale of one hundred milliseconds after switching off the\nlaser, resulting in long-lived enrichment of shallow NV-. The beneficial effect\nof photoconversion is less marked in nanostructured samples. Our results are\nimportant to inform the design of samples and experimental procedures for\napplications relying on ensembles of shallow NV- centers in diamond."
    },
    {
        "anchor": "Read-out and Dynamics of the Qubit Built on Three Quantum Dots: We present a model of a qubit built of a three coherently coupled quantum\ndots with three spins in a triangular geometry. The qubit states are encoded in\nthe doublet subspace and they are controlled by a gate voltage, which breaks\nthe triangular symmetry of the system. We show how to prepare the qubit and to\nperform one qubit operations. A new type of the current blockade effect will be\ndiscussed. The blockade is related with an asymmetry of transfer rates from the\nelectrodes to different doublet states and is used to read-out of the dynamics\nof the qubit state. Our research also presents analysis of the Rabi\noscillations, decoherence and leakage processes in the doublets subspace.",
        "positive": "Quantum Interference and Coherent Population Trapping in a Double\n  Quantum Dot: Quantum interference is a natural consequence of wave-particle duality in\nquantum mechanics, and is widely observed at the atomic scale. One interesting\nmanifestation of quantum interference is coherent population trapping (CPT),\nfirst proposed in three-level driven atomic systems and observed in quantum\noptical experiments. Here, we demonstrate CPT in a gate-defined semiconductor\ndouble quantum dot (DQD), with some unique twists as compared to the atomic\nsystems. Specifically, we observe CPT in both driven and non-driven situations.\nWe further show that CPT in a driven DQD could be used to generate adiabatic\nstate transfer. Moreover, our experiment reveals a non-trivial modulation to\nthe CPT caused by the longitudinal driving field, yielding an odd-even effect\nand a tunable CPT."
    },
    {
        "anchor": "Narrow photoluminescence peak of epitaxial MoS$_2$ on graphene/Ir(111): We report on the observation of photoluminescence (PL) with a narrow 18 meV\npeak width from molecular beam epitaxy grown MoS$_2$ on graphene/Ir(111). This\nobservation is explained in terms of a weak graphene-MoS$_2$ interaction that\nprevents PL quenching expected for a metallic substrate. The weak interaction\nof MoS$_2$ with the graphene is highlighted by angle-resolved photoemission\nspectroscopy and temperature dependent Raman spectroscopy. These methods reveal\nthat there is no hybridization between electronic states of graphene and\nMoS$_2$ and a different thermal expansion of graphene and MoS$_2$. Molecular\nbeam epitaxy grown MoS2 on graphene is therefore an important platform for\noptoelectronics which allows for large area growth with controlled properties.",
        "positive": "Wiedemann-Franz Law for Molecular Hopping Transport: The Wiedemann-Franz (WF) law is a fundamental result in solid-state physics\nthat relates the thermal and electrical conductivity of a metal. It is derived\nfrom the predominant origin of energy conversion in metals: the motion of\nquasi-free charge-carrying particles. Here, an equivalent WF relationship is\ndeveloped for molecular systems in which charge carriers are moving not as free\nparticles but instead hop between redox sites. We derive a concise analytical\nrelationship between the electrical and thermal conductivity generated by\nelectron hopping in molecular systems and find that the linear temperature\ndependence of their ratio as expressed in the standard WF law is replaced by a\nlinear dependence on the nuclear reorganization energy associated with the\nelectron hopping process. The robustness of the molecular WF relation is\nconfirmed by examining the conductance properties of a paradigmatic molecular\njunction. This result opens a new way to analyze conductivity in molecular\nsystems, with possible applications advancing the design of molecular\ntechnologies that derive their function from electrical and/or thermal\nconductance."
    },
    {
        "anchor": "A numerical investigation of a piezoelectric surface acoustic wave\n  interaction with a one-dimensional channel: We investigate the propagation of a piezoelectric surface acoustic wave (SAW)\nacross a GaAs/Al$_X$Ga$_{1-X}$As heterostructure surface, on which there is\nfixed a metallic split-gate. Our method is based on a finite element\nformulation of the underlying equations of motion, and is performed in\nthree-dimensions fully incorporating the geometry and material composition of\nthe substrate and gates. We demonstrate attenuation of the SAW amplitude as a\nresult of the presence of both mechanical and electrical gates on the surface.\nWe show that the incorporation of a simple model for the screening by the\ntwo-dimensional electron gas (2DEG), results in a total electric potential\nmodulation that suggests a mechanism for the capture and release of electrons\nby the SAW. Our simulations suggest the absence of any significant turbulence\nin the SAW motion which could hamper the operation of SAW based quantum devices\nof a more complex geometry.",
        "positive": "Model for the magnetoresistance and Hall coefficient of inhomogeneous\n  graphene: We show that when bulk graphene breaks into n-type and p-type puddles, the\nin-plane resistivity becomes strongly field dependent in the presence of a\nperpendicular magnetic field, even if homoge- neous graphene has a\nfield-independent resistivity. We calculate the longitudinal resistivity\n\\rho_{xx} and Hall resistivity \\rho_{xy} as a function of field for this\nsystem, using the effective-medium approximation. The conductivity tensors of\nthe individual puddles are calculated using a Boltzmann approach suit- able for\nthe band structure of graphene near the Dirac points. The resulting resistivity\nagrees well with experiment, provided that the relaxation time is weakly\nfield-dependent. The calculated Hall resistivity has the sign of the majority\ncarrier and vanishes when there are equal number of n and p type puddles."
    },
    {
        "anchor": "Quantum Electronic Circuit Simulation of Generalized sine-Gordon Models: Investigation of strongly interacting, nonlinear quantum field theories\n(QFT-s) remains one of the outstanding challenges of modern physics. Here, we\ndescribe analog quantum simulators for nonlinear QFT-s using mesoscopic\nsuperconducting circuit lattices. Using the Josephson effect as the source of\nnonlinear interaction, we investigate generalizations of the quantum\nsine-Gordon model. In particular, we consider a two-field generalization, the\ndouble sine-Gordon model. In contrast to the sine-Gordon model, this model can\nbe purely quantum integrable, when it does not admit a semi-classical\ndescription - a property that is generic to many multi-field QFT-s. The primary\ngoal of this work is to investigate different thermodynamic properties of the\ndouble sine-Gordon model and propose experiments that can capture its subtle\nquantum integrability. First, we analytically compute the mass-spectrum and the\nground state energy in the presence of an external `magnetic' field using Bethe\nansatz and conformal perturbation theory. Second, we calculate the\nthermodynamic Bethe ansatz equations for the model and analyze its finite\ntemperature properties. Third, we propose experiments to verify the theoretical\npredictions.",
        "positive": "Surface state band mobility and thermopower in semiconducting bismuth\n  nanowires: Many thermoelectrics like Bi exhibit Rashba spin-orbit surface bands for\nwhich topological insulator behavior consisting of ultrahigh mobilities and\nenhanced thermopower has been predicted. Bi nanowires realize surface-only\nelectronic transport since they become bulk insulators when they undergo the\nbulk semimetal-semiconductor transition as a result of quantum confinement for\ndiameters close to 50 nm. We studied 20-, 30-, 50- and 200-nm trigonal Bi\nwires. Shubnikov-de Haas magnetoresistance oscillations caused by surface\nelectrons and bulklike holes enable the determination of their densities and\nmobilities. Surface electrons have high mobilities exceeding 2(m^2)/(Vsec) and\ncontribute strongly to the thermopower, dominating for temperatures T< 100 K.\nThe surface thermopower is - 1.2 T microvolt/(K^2), a value that is consistent\nwith theory, raising the prospect of developing nanoscale thermoelectrics based\non surface bands."
    },
    {
        "anchor": "Magnetic Domain Wall Floating on a Spin Superfluid: We theoretically investigate the transfer of angular momentum between a spin\nsuperfluid and a domain wall in an exchange coupled easy-axis and easy-plane\nmagnetic insulator system. A domain wall in the easy-axis magnet absorbs spin\nangular momentum via disrupting the flow of a superfluid spin current in the\neasy-plane magnet. Focusing on an open geometry, where the spin current is\ninjected electrically via a nonequilibrium spin accumulation, we derive\nanalytical expressions for the resultant superfluid-mediated motion of the\ndomain wall. The analytical results are supported by micromagnetic simulations.\nThe proposed phenomenon extends the regime of magnon-driven domain-wall motion\nto the case when the magnons are condensed and exhibit superfluidity.\nFurthermore, by controlling the pinning of the domain wall, we propose a\nrealization of a reconfigurable spin transistor. The long-distance\ndissipationless character of spin superfluids can thus be exploited for\nmanipulating soliton-based memory and logic devices.",
        "positive": "Fractals of graphene quantum dots in photoluminescence of shungite: Photoluminescence of graphene quantum dots (GQDs) of shungite, attributed to\nindividual fragments of reduced graphene oxide (rGO), has been studied for the\nfrozen rGO colloidal dispersions in water, carbon tetrachloride, and toluene.\nMorphological study shows a steady trend of GQDs to form fractals and a drastic\nchange in the colloids fractal structure caused by solvent was reliably\nestablished. Spectral study reveals a dual character of emitting centers:\nindividual GQDs are responsible for the spectra position while fractal\nstructure of GQD colloids provides high broadening of the spectra due to\nstructural inhomogeneity of the colloidal dispersions and a peculiar dependence\non excitation wavelength. For the first time, photoluminescence spectra of\nindividual GQDs were observed in frozen toluene dispersions which pave the way\nfor a theoretical treatment of GQD photonics."
    },
    {
        "anchor": "Character of electronic states in graphene antidot lattices: Flat bands\n  and spatial localization: Graphene antidot lattices have recently been proposed as a new breed of\ngraphene-based superlattice structures. We study electronic properties of\ntriangular antidot lattices, with emphasis on the occurrence of dispersionless\n(flat) bands and the ensuing electron localization. Apart from strictly flat\nbands at zero-energy (Fermi level), whose existence is closely related to the\nbipartite lattice structure, we also find quasi-flat bands at low energies. We\npredict the real-space electron density profiles due to these localized states\nfor a number of representative antidot lattices. We point out that the studied\nlow-energy, localized states compete with states induced by defects on the\nsuperlattice scale in this system which have been proposed as hosts for\nelectron spin qubits. We furthermore suggest that local moments formed in these\nmidgap zero-energy states may be at the origin of a surprising saturation of\nthe electron dephasing length observed in recent weak localization measurements\nin graphene antidot lattices.",
        "positive": "Emergent Magneto-multipoles and Nonlinear Responses of a Magnetic\n  Hopfion: The three-dimensional emergent magnetic field $\\textbf{B}^e$ of a magnetic\nhopfion gives rise to emergent magneto-multipoles in a similar manner to the\nmultipoles of classical electromagnetic field. Here, we show that the nonlinear\nresponses of a hopfion are characterized by its emergent magnetic toroidal\nmoment ${T}^e_z = \\frac{1}{2}\\int (\\textbf{r}\\times \\textbf{B}^e)_z dV$ and\nemergent magnetic octupole component ${\\it \\Gamma}^e =\\int [(x^2+y^2)B^e_z - xz\nB^e_x - y z B^e_y] dV$. The hopfion exhibits nonreciprocal dynamics (nonlinear\nhopfion Hall effect) under an ac driving current applied along (perpendicular\nto) the direction of ${T}^e_z$. The sign of nonreciprocity and nonlinear Hall\nangle is determined by the polarity and chirality of hopfion. The nonlinear\nelectrical transport induced by a magnetic hopfion is also discussed. This work\nreveals the vital roles of emergent magneto-multipoles in nonlinear hopfion\ndynamics and could stimulate further investigations on the dynamical responses\nof topological spin textures induced by emergent electromagnetic multipoles."
    },
    {
        "anchor": "Phase diagram of the dissipative quantum particle in a box: We analyze the phase diagram of a quantum particle confined to a finite\nchain, subject to a dissipative environment described by an Ohmic spectral\nfunction. Analytical and numerical techniques are employed to explore both the\nperturbative and non-perturbative regime of the model. For small dissipation\nthe coupling to the environment leads to a narrowing of the density\ndistribution, and to a displacement towards the center of the array of\naccessible sites. For large values of the dissipation, we find a phase\ntransition to a doubly degenerate phase which reflects the formation of an\ninhomogeneous effective potential within the array.",
        "positive": "Full three-dimensonal reconstruction of the dyadic Green tensor from\n  electron energy loss spectroscopy of plasmonic nanoparticles: Electron energy loss spectroscopy (EELS) has emerged as a powerful tool for\nthe investigation of plasmonic nanoparticles, but the interpretation of EELS\nresults in in terms of optical quantities, such as the photonic local density\nof states, remains challenging. Recent work has demonstrated that under\nrestrictive assumptions, including the applicability of the quasistatic\napproximation and a plasmonic response governed by a single mode, one can\nrephrase EELS as a tomography scheme for the reconstruction of plasmonic\neigenmodes. In this paper we lift these restrictions by formulating EELS as an\ninverse problem, and show that the complete dyadic Green tensor can be\nreconstructed for plasmonic particles of arbitrary shape. The key steps\nunderlying our approach are a generic singular value decomposition of the\ndyadic Green tensor and a compressed sensing optimization for the determination\nof the expansion coefficients. We demonstrate the applicability of our scheme\nfor prototypical nanorod, bowtie, and cube geometries."
    },
    {
        "anchor": "Combining Topological Hardware and Topological Software: Color Code\n  Quantum Computing with Topological Superconductor Networks: We present a scalable architecture for fault-tolerant topological quantum\ncomputation using networks of voltage-controlled Majorana Cooper pair boxes,\nand topological color codes for error correction. Color codes have a set of\ntransversal gates which coincides with the set of topologically protected gates\nin Majorana-based systems, namely the Clifford gates. In this way, we establish\ncolor codes as providing a natural setting in which advantages offered by\ntopological hardware can be combined with those arising from topological\nerror-correcting software for full-fledged fault-tolerant quantum computing. We\nprovide a complete description of our architecture including the underlying\nphysical ingredients. We start by showing that in topological superconductor\nnetworks, hexagonal cells can be employed to serve as physical qubits for\nuniversal quantum computation, and present protocols for realizing\ntopologically protected Clifford gates. These hexagonal cell qubits allow for a\ndirect implementation of open-boundary color codes with ancilla-free syndrome\nreadout and logical $T$-gates via magic state distillation. For concreteness,\nwe describe how the necessary operations can be implemented using networks of\nMajorana Cooper pair boxes, and give a feasibility estimate for error\ncorrection in this architecture. Our approach is motivated by nanowire-based\nnetworks of topological superconductors, but could also be realized in\nalternative settings such as quantum Hall-superconductor hybrids.",
        "positive": "Dynamics at T -> 0 in the half-integer isotropic high spin molecules: We investigate the dynamical spin-spin auto-correlation function of the\nisotropic high spin molecules CrCu$_{6}$ (S=9/2), CrNi$_{6}$ (S=15/2) and\nCrMn$_{6}$ (S=27/2), using magnetization, $\\mu$SR and NMR measurements. We find\nthat the field autocorrelation time $\\tau$ of the molecule's spin at zero and\nlow fields is nearly temperature independent as $T\\to 50$ mK. The high\ntemperatures $\\tau$ is very different between the molecules. Surprisingly, it\nis identical ($\\sim$ 10 nsec) at low temperature. This suggests that $\\tau$ is\ngoverned by hyperfine interactions."
    },
    {
        "anchor": "Photon Assisted Tunneling in Quantum Dots: We review experiments on single electron transport through single quantum\ndots in the presence of a microwave signal. In the case of a small dot with\nwell-resolved discrete energy states, the applied high-frequency signal allows\nfor inelastic tunnel events that involve the exchange of photons with the\nmicrowave field. These photon assisted tunneling (PAT) processes give rise to\nsideband resonances in addition to the main resonance. Photon absorption can\nalso lead to tunneling via excited states instead of tunneling via the ground\nstate of the quantum dot.",
        "positive": "Currents in metallic rings with quantum dot: Currents in a metallic ring with a quantum dot are studied in the framework\nof a Langevin equation for a magnetic flux passing through the ring. Two\nscenarios are considered: one in which thermal fluctuations of the dissipative\npart of the current are modelled by classical Johnson-Nyquist noise and one in\nwhich quantum character of thermal fluctuations is taken into account in terms\nof a quantum Smoluchowski equation. The impact of the amplitude and phase of\nthe transmission coefficient of the electron through a quantum dot on current\ncharacteristics is analyzed. In tailored parameter regimes, both scenarios can\nexhibit the transition from para-- to diamagnetic response of the ring current\nversus external magnetic flux."
    },
    {
        "anchor": "Energy bands of atomic monolayers of various materials: Possibility of\n  energy gap engineering: The mobility of graphene is very high because the quantum Hall effects can be\nobserved even at room temperature. Graphene has the potential of the material\nfor novel devices because of this high mobility. But the energy gap of graphene\nis zero, so graphene can not be applied to semiconductor devices such as\ntransistors, LEDs, etc. In order to control the energy gaps, we propose atomic\nmonolayers which consist of various materials besides carbon atoms. To examine\nthe energy dispersions of atomic monolayers of various materials, we calculated\nthe electronic states of these atomic monolayers using density functional\ntheory with structural optimizations. The quantum chemical calculation software\n\"Gaussian 03\" was used under periodic boundary conditions. The calculation\nmethod is LSDA/6-311G(d,p), B3LYP/6-31G(d), or B3LYP/6-311G(d,p). The\ncalculated materials are C (graphene), Si (silicene), Ge, SiC, GeC, GeSi, BN,\nBP, BAs, AlP, AlAs, GaP, and GaAs. These atomic monolayers can exist in the\nflat honeycomb shapes. The energy gaps of these atomic monolayers take various\nvalues. Ge is a semimetal; AlP, AlAs, GaP, and GaAs are indirect\nsemiconductors; and others are direct semiconductors. We also calculated the\nchange of energy dispersions accompanied by the substitution of the atoms. Our\nresults suggest that the substitution of impurity atoms for monolayer materials\ncan control the energy gaps of the atomic monolayers. We conclude that atomic\nmonolayers of various materials have the potential for novel devices.",
        "positive": "Wideband superconducting nanotube electrometer: We have investigated the microwave response of nanotube Josephson junctions\nat 600-900 MHz at microwave powers corresponding to currents from 0 to $2\\times\nI_{\\mathrm C}$ in the junction. Compared with theoretical modeling, the\nresponse of the junctions correspond well to the lumped element model of\nresistively and capacitively shunted junction. We demonstrate the operation of\nthese superconducting FETs as charge detectors at high frequencies without any\nmatching circuits. Gate-voltage-induced charge $Q_{\\rm G}$ modifies the\ncritical current $I_{\\rm C}$, which changes the effective impedance of the\njunction under microwave irradiation. This change, dependent on the transfer\ncharacteristics $dI_{\\mathrm C}/dQ_{\\rm G}$, modifies the reflected signal and\nit can be used for wide band electrometry. We measure a sensitivity of\n$3.1\\times10^{-5}$ $e/\\sqrt{\\mathrm{Hz}}$ from a sample which has a maximum\nswitching current of 2.6 nA."
    },
    {
        "anchor": "Quantum algorithms for Josephson networks: We analyze possible implementations of quantum algorithms in a system of\n(macroscopic) Josephson charge qubits. System layout and parameters to realize\nthe Deutsch algorithm with up to three qubits are provided. Special attention\nis paid to the necessity of entangled states in the various implementations.\nFurther, we demonstrate explicitely that the gates to implement the\nBernstein-Vazirani algorithm can be realized by using a system of uncoupled\nqubits.",
        "positive": "Classical and quantum magnetization reversal studied in nanometer-sized\n  particles and clusters: Nanometer-sized magnetic particles have generated continuous interest as the\nstudy of their properties has proved to be scientifically and technologically\nvery challenging. In this article we reviewed the most important theories and\nexperimental results concerning the magnetization reversal of single-domain\nparticles,clusters and molecular clusters. Sect.1 reviews briefly the commonly\nused measuring techniques. Among them, electrical transport measurements, Hall\nprobes and micro-SQUID techniques seem to be the most convenient techniques for\nlow temperature measurements. Sect.2 discusses the mechanisms of magnetization\nreversal in single domain particles at zero Kelvin. The influence of\ntemperature on the magnetization reversal is reported in Sect.3. Finally,\nSect.4 shows that for very small systems or very low temperature, magnetization\ncan reverse via quantum tunneling. The boundary between classical and quantum\nphysics has become a very attractive field of research. This section discusses\ndetailed measurements which demonstrated that molecular magnets offer an unique\nopportunity to explore the quantum dynamics of a large but finite spin. We then\ndiscussed tunneling in nanoparticles and showed how one might give a definite\nproof of their quantum character at low temperature."
    },
    {
        "anchor": "Spin and orbital mechanisms of the magneto-gyrotropic photogalvanic\n  effects in GaAs/AlGaAs quantum well structures: We report on the study of the linear and circular magneto-gyrotropic\nphotogalvanic effect (MPGE) in GaAs/AlGaAs quantum well structures. Using the\nfact that in such structures the Land\\'e-factor g* depends on the quantum well\n(QW) width and has different signs for narrow and wide QWs, we succeeded to\nseparate spin and orbital contributions to both MPGEs. Our experiments show\nthat, for most quantum well widths, the PGEs are mainly driven by spin-related\nmechanisms, which results in a photocurrent proportional to the g* factor. In\nstructures with a vanishingly small g* factor, however, linear and circular\nMPGE are also detected, proving the existence of orbital mechanisms.",
        "positive": "Effective Doping of Monolayer Phosphorene by Surface Adsorption of Atoms\n  for Electronic and Spintronic Applications: We study the effect of surface adsorption of 27 different adatoms on the\nelectronic and magnetic properties of monolayer black phosphorus using density\nfunctional theory. Choosing a few representative elements from each group,\nranging from alkali metals (group I) to halogens (group VII), we calculate the\nband structure, density of states, magnetic moment and effective mass for the\nenergetically most stable location of the adatom on monolayer phosphorene. We\npredict that group I metals (Li, Na, K), and group III adatoms (Al, Ga, In) are\neffective in enhancing the n-type mobile carrier density, with group III\nadatoms resulting in lower effective mass of the electrons, and thus higher\nmobilities. Furthermore we find that the adatoms of transition metals Ti and\nFe, produce a finite magnetic moment (1.87 and 2.31 $\\mu_B$) in monolayer\nphosphorene, with different band gap and electronic effective masses (and thus\nmobilities), which approximately differ by a factor of 10 for spin up and spin\ndown electrons opening up the possibility for exploring spintronic\napplications."
    },
    {
        "anchor": "Nature of Spin Hall Effect in a finite Ballistic Two-Dimensional System\n  with Rashba and Dresselhaus spin-orbit interaction: The spin Hall effect in a finite ballistic two-dimensional system with Rashba\nand Dresselhaus spin-orbit interaction is studied numerically. We find that the\nspin Hall conductance is very sensitive to the transverse measuring location,\nthe shape and size of the device, and the strength of the spin-orbit\ninteraction. Not only the amplitude of spin Hall conductance but also its sign\ncan change. This non-universal behavior of the spin Hall effect is essentially\ndifferent from that of the charge Hall effect, in which the Hall voltage is\nalmost invariant with the transverse measuring site and is a monotonic function\nof the strength of the magnetic field. These surprise behavior of the spin Hall\nconductance are attributed to the fact that the eigenstates of the spin Hall\nsystem is extended in the transverse direction and do not form the edge states.",
        "positive": "Time-dependent transport of a localized surface plasmon through a linear\n  array of metal nanoparticles: Precursor and normal mode contributions: We theoretically investigate the time-dependent transport of a localized\nsurface plasmon excitation through a linear array of identical and\nequidistantly spaced metal nanoparticles. Two different signals propagating\nthrough the array are found: one traveling with the group velocity of the\nsurface plasmon polaritons of the system and damped exponentially, and the\nother running with the speed of light and decaying in a power-~law fashion, as\n$x^{-1}$ and $x^{-2}$ for the transversal and longitudinal polarizations,\nrespectively. The latter resembles the Sommerfeld-Brillouin forerunner and has\nnot been identified in previous studies. The contribution of this signal\ndominates the plasmon transport at large distances. In addition, even though\nthis signal is spread in the propagation direction and has the lateral\ndimension larger than the wavelength, the field profile close to the chain axis\ndoes not change with distance, indicating that this part of the signal is\nconfined to the array."
    },
    {
        "anchor": "Radiative topological states in resonant photonic crystals: We present a theory of topological edge states in one-dimensional resonant\nphotonic crystals with a compound unit cell. Contrary to the traditional\nelectronic topological states the states under consideration are radiative,\ni.e., they decay in time due to the light escape through the structure\nboundaries. We demonstrate that the states survive despite their radiative\ndecay and can be detected both in time- and frequency-dependent light\nreflection.",
        "positive": "Imaging transverse electron focusing in semiconducting heterostructures\n  with spin-orbit coupling: Transverse electron focusing in two-dimensional electron gases (2DEGs) with\nstrong spin-orbit coupling is revisited. The transverse focusing is related to\nthe transmission between two contacts at the edge of a 2DEG when a\nperpendicular magnetic field is applied. Scanning probe microscopy imaging\ntechniques can be used to study the electron flow in these systems. Using\nnumerical techniques we simulate the images that could be obtained in such\nexperiments. We show that hybrid edge states can be imaged and that the\noutgoing flux can be polarized if the microscope tip probe is placed in\nspecific positions."
    },
    {
        "anchor": "Geometric engineering of viscous magnetotransport in a two-dimensional\n  electron system: In this study, we present our experimental investigation on the\nmagnetotransport properties of a two-dimensional electron system in GaAs\nquantum wells utilizing a variety of device geometries, including obstacles\nwith thin barriers and periodic width variations. Our primary focus is to\nexplore the impact of these geometries on the electron viscous flow parameters,\nenabling precise manipulation of hydrodynamic effects under controlled\nconditions. Through an analysis of the large negative magnetoresistivity and\nzero field resistivity, we deduce the scattering times for electron-electron\nand electron-phonon interactions, as well as the effective channel width. Our\nfindings confirm that the system under investigation serves as a tunable\nexperimental platform for investigating hydrodynamic transport regimes at\ntemperatures above 10 K.",
        "positive": "Quantum Hall Effect of Weyl Fermions in Semiconducting n-type Tellurene: Dirac and Weyl nodal materials can host low-energy relativistic\nquasiparticles. Under strong magnetic fields, the topological properties of\nDirac/Weyl materials can directly manifest through quantum Hall states.\nHowever, most Dirac/Weyl nodes generically exist in semimetals without\nexploitable bandgaps due to their accidental band-crossing origin. Here we\nreport the first experimental observation of Weyl fermions in a semiconductor.\nTellurene, the 2D form of tellurium, possesses chiral crystal structure which\ninduces unconventional Weyl nodes with a hedgehog-like radial spin texture near\nthe conduction band edge. We synthesize high-quality n-type tellurene by a\nhydrothermal method with subsequent dielectric doping and detect a\ntopologically non-trivial pi Berry phase in quantum Hall sequences. Our work\nexpands the spectrum of Weyl matter into semiconductors and offers a new\nplatform to design novel quantum devices by marrying the advantages of\ntopological materials to versatile semiconductors."
    },
    {
        "anchor": "Measurement of thermal conductance of silicon nanowires at low\n  temperature: We have performed thermal conductance measurements on individual single\ncrystalline silicon suspended nanowires. The nanowires (130 nm thick and 200 nm\nwide) are fabricated by e-beam lithography and suspended between two separated\npads on Silicon On Insulator (SOI) substrate. We measure the thermal\nconductance of the phonon wave guide by the 3&#61559; method. The cross-section\nof the nanowire approaches the dominant phonon wavelength in silicon which is\nof the order of 100 nm at 1K. Above 1.3K the conductance behaves as T3, but a\ndeviation is measured at the lowest temperature which can be attributed to the\nreduced geometry.",
        "positive": "Influence of structural disorder and large-scale geometric fluctuations\n  on the Coherent Transport of Metallic Junctions and Molecular Wires: Structural disorder is present in almost all experimental measurements of\nelectronic transport through single molecules or molecular wires. To assess its\ninfluence on the conductance is computationally demanding, because a large\nnumber of conformations must be considered. Here we analyze an approximate\nrecursive layer Green function approach for the ballistic transport through\nquasi one-dimensional nano-junctions. We find a rapid convergence of the method\nwith its control parameter, the layer thickness, and good agreement with\nexisting experimental and theoretical data. Because the computational effort\nrises only linearly with system size, this method permits treatment of very\nlarge systems. We investigate the conductance of gold- and silver wires of\ndifferent sizes and conformations. For weak electrode disorder and imperfect\ncoupling between electrode and wire we find conductance variations of\napproximately 20%. Overall we find the conductance of silver junctions well\ndescribed by the immediate vicinity of narrowest point in the junction, a\nresult that may explain the observation of well-conserved conductance plateaus\nin recent experiments on silver junctions. In an application to flexible\noligophene wires, we find that strongly distorted conformations that are\nsterically forbidden at zero temperature, contribute significantly to the\nobserved average zero-bias conductance of the molecular wire."
    },
    {
        "anchor": "Superconducting Orbital Magnetoelectric Effect and its Evolution across\n  the Superconductivity Normal Metal Phase Transition: Superconducting magnetoelectric effect, which is the current-induced\nmagnetization in a superconductor, mainly focused on the spin magnetization in\nprevious studies, but ignore the effect of the orbital magnetic moments carried\nby the paired Bloch electrons. In this work, we show that orbital magnetic\nmoments in superconductors can induce large orbital magnetization in the\npresence of a current. We constructed a unified description for the\ncurrent-induced spin and orbital magnetization across the superconductivity\nnormal metal phase transition. We find that in a superconductor with uniform\npairing, the current-induced magnetization at a given current density is the\nsame as that in its normal metal state, while with the nonuniform\nsuperconducting pairing, the current-induced magnetization exhibits an abrupt\nchange in magnitude near the superconductivity normal metal phase transition.\nImportantly, our theory predicts the orbital magnetoelectric effect in\nsuperconducting twisted bilayer graphene which has paired Bloch electrons with\nlarge orbital magnetic moments and negligible spin-orbit coupling. We propose\nthat the measurement of the current-induced orbital magnetoelectric effect can\nbe used to detect the possible nonuniform pairings in twisted bilayer graphene\nand other newly discovered superconductors with non-trivial Berry curvatures.",
        "positive": "Three-dimensional nanoimprint lithography using two-photon lithography\n  master samples: We demonstrate three-dimensional (3-D) nanoimprint lithography using master\nsamples initially structured by two-photon lithography. Complex geometries like\nmicro prisms, micro parabolic concentrators, micro lenses and other micrometer\nsized objects with nanoscale features are three-dimensionally fabricated using\ntwo-photon lithography. Stamps made out of polydimethylsiloxane are then cast\nusing the two-photon lithographically structured samples as master samples.\nHereby, expensive serial nano 3-D printing is transformed into scalable\nparallel 3-D nanoimprint lithography. Furthermore, the transition from\ntwo-photon lithography to imprint lithography increases the freedom in\nsubstrate and ink choice significantly. We demonstrate printing on textured\nsurfaces as well as residue-free printing with silver ink using capillary\naction."
    },
    {
        "anchor": "Quantum Transport in Graphene Using Surface Acoustic Wave Resonators: Surface acoustic waves (SAWs) provide a contactless method for measuring the\nwavevector-dependent conductivity. This technique has been used to discover\nemergent length scales in the fractional quantum Hall regime of traditional,\nsemiconductor-based heterostructures. SAWs would appear to be an ideal match\nfor van der Waals (vdW) heterostructures, but the right combination of\nsubstrate and experimental geometry to allow access to the quantum transport\nregime has not yet been found. We demonstrate that SAW resonant cavities\nfabricated on LiNbO$_3$ substrates can be used to access the quantum Hall\nregime of high-mobility, hexagonal boron nitride (hBN) encapsulated graphene\nheterostructures. Our work establishes SAW resonant cavities as a viable\nplatform for performing contactless conductivity measurements in the quantum\ntransport regime of vdW materials.",
        "positive": "The spin-double refraction in two-dimensional electron gas: We briefly review the phenomenon of the spin-double refraction that\noriginates at an interface separating a two-dimensional electron gas with\nRashba spin-orbit coupling from a one without. We demonstrate how this\nphenomenon in semiconductor heterostructures can produce and control a\nspin-polarized current without ferromagnetic leads."
    },
    {
        "anchor": "Selective branching, quenching, and converting of topological modes: A salient feature of topological phases are surface states and many of the\nwidely studied physical properties are directly tied to their existence.\nAlthough less explored, a variety of topological phases can however similarly\nbe distinguished by their response to localized flux defects, resulting in the\nbinding of modes whose stability can be traced back to that of convectional\nedge states. The reduced dimensionality of these objects renders the\npossibility of arranging them in distinct geometries, such as arrays that\nbranch or terminate in the bulk. We show that the prospect of hybridizing the\nmodes in such new kinds of channels poses profound opportunities in a dynamical\ncontext. In particular, we find that creating junctions of $\\pi$-flux chains or\nextending them as function of time can induce transistor and stop-and-go\neffects. Pending controllable initial conditions certain branches of the\nextended defect array can be actively biased. Discussing these physical effects\nwithin a generally applicable framework that relates to a variety of\nestablished artificial topological materials, such as mass-spring setups and LC\ncircuits, our results offer an avenue to explore and manipulate new transport\neffects that are rooted in the topological characterization of the underlying\nsystem.",
        "positive": "Interference Effect of Majorana Fermions in a Spin-orbit Coupled\n  Superconducting Wire: Two majorana Fermions (MFs) localized at the two ends of the topological\nsuperconducting wire can interfere with each other and form the well known\n$4\\pi$ Josephson current. We reveal that the density of states (Dos) for the\nelectron part and the hole part also follow a parity correlated $4\\pi$ period\noscillation, while the Dos displays a $2\\pi$ period oscillation when two\ntrivial states interfere with each other. Thus, the period of Dos oscillation\ncan be used to distinguish the MFs from the trivial localized states.\nInterestingly, such phenomena can be directly observed in a short\nsuperconducting wire controlled by the gate voltage. This largely simplifies\nthe experimental setup. We suggest that the interference effects can be\ndetected through two STM leads or two norm leads."
    },
    {
        "anchor": "Oscillatory surface dichroism of an insulating topological insulator\n  Bi2Te2Se: Using circular dichroism-angle resolved photoemission spectroscopy\n(CD-ARPES), we report a study of the effect of angular momentum transfer\nbetween polarized photons and topological surface states on the surface of\nhighly bulk insulating topological insulator Bi2Te2Se. The photoelectron\ndichroism is found to be strongly modulated by the frequency of the helical\nphotons including a dramatic sign-flip. Our results suggest that the observed\ndichroism and its sign-flip are consequences of strong coupling between the\nphoton field and the spin-orbit nature of the Dirac modes on the surface. Our\nstudies reveal the intrinsic dichroic behavior of topological surface states\nand point toward the potential utility of bulk insulating topological\ninsulators in device applications.",
        "positive": "Controlled Coulomb effects in core-shell quantum rings: We analyse theoretically the possibilities of contactless control of in-gap\nstates formed by a pair of electrons confined in a triangular quantum ring. The\nin-gap states are corner-localized states associated with two electrons\noccupying the same corner area, and thus shifted to much higher energies than\nother corner states, but still they are below the energies of\ncorner-side-localized states. We show how the energies, degeneracy and\nsplittings between consecutive levels change with the orientation of an\nexternal electric field relatively to the polygonal cross section. We also show\nhow absorption changes in the presence of external electric and magnetic\nfields."
    },
    {
        "anchor": "Nonlinear voltage dependence of the shot noise in mesoscopic degenerate\n  conductors with strong electron-electron scattering: It is shown that measurements of zero-frequency shot-noise can provide\ninformation on electron-electron interaction, because the strong interaction\nresults in the nonlinear voltage dependence of the shot noise in metallic\nwires. This is due to the fact that the Wiedemann-Franz law is no longer valid\nin the case of considerable electron-electron interaction. The deviations from\nthis law increase the noise power and make it dependent strongly on the ratio\nof electron-electron and electron-impurity scattering rates.",
        "positive": "Effect of an InP/In$_{0.53}$Ga$_{0.47}$As Interface on Spin-orbit\n  Interaction in In$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As\n  Heterostructures: We report the effect of the insertion of an InP/In$_{0.53}$Ga$_{47}$As\nInterface on Rashba spin-orbit interaction in\nIn$_{0.52}$Al$_{0.48}$As/In$_{0.53}$Ga$_{0.47}$As quantum wells. A small spin\nsplit-off energy in InP produces a very intriguing band lineup in the valence\nbands in this system. With or without this InP layer above the\nIn$_{0.53}$Ga$_{47}$As well, the overall values of the spin-orbit coupling\nconstant $\\alpha$ turned out to be enhanced or diminished for samples with the\nfront- or back-doping position, respectively. These experimental results, using\nweak antilocalization analysis, are compared with the results of the\n$\\mathbf{k\\cdot p}$ theory. The actual conditions of the interfaces and\nmaterials should account for the quantitative difference in magnitude between\nthe measurements and calculations."
    },
    {
        "anchor": "Strain-induced gap modification in black phosphorus: The band structure of single-layer black phosphorus and the effect of strain\nare predicted using density functional theory and tight-binding models. Having\ndetermined the localized orbital composition of the individual bands from\nfirst-principles, we use the system symmetry to write down the effective\nlow-energy Hamiltonian at the $\\Gamma$ point. From numerical calculations and\narguments based on the crystal structure of the material, we show that the\ndeformation in the direction normal to the plane can be use to change the gap\nsize and induce a semiconductor-metal transition.",
        "positive": "Anatomy of magnetic anisotropy induced by Rashba spin-orbit interactions: Magnetic anisotropy controls the orientational stability and switching\nproperties of magnetic states, and therefore plays a central role in\nspintronics. First-principles density-functional-theory calculations are able,\nin most cases, to provide a satisfactory description of bulk and interface\ncontributions to the magnetic anisotropy of particular film/substrate\ncombinations. In this paper we focus on achieving a simplified understanding of\nsome trends in interfacial magnetic anisotropy based on a simple tight-binding\nmodel for quasiparticle states in a heavy-metal/ferromagnetic-metal bilayer\nfilm. We explain how to calculate the magnetic anisotropy energy of this model\nfrom the quasiparticle spin-susceptibility, compare with more conventional\napproaches using either a perturbative treatment of spin-orbit interactions or\na direct calculation of the dependence of the energy on the orientation of the\nmagnetization, and show that the magnetic anisotropy can be interpreted as a\ncompetition between a Fermi-sea term favoring perpendicular anisotropy and a\nFermi-surface term favoring in-plane anisotropy. Based on this finding, we\nconclude that perpendicular magnetic anisotropy should be expected in an\nitinerant electron thin film when the spin magnetization density is larger than\nthe product of the band exchange splitting and the Fermi level\ndensity-of-states of the magnetic state."
    },
    {
        "anchor": "Evidence of localization effect on photoelectron transport induced by\n  alloy disorder in nitride semiconductor compounds: Near-bandgap photoemission spectroscopy experiments were performed on p-GaN\nand p-InGaN/GaN photocathodes activated to negative electron affinity. The\nphotoemission quantum yield of the InGaN samples drops by more than one order\nof magnitude when the temperature is decreased while it remains constant on the\nGaN sample. This indicates a freezing of photoelectron transport in p-InGaN\nthat we attribute to electron localization in the fluctuating potential induced\nby the alloy disorder. This interpretation is confirmed by the disappearence at\nlow temperature of the peak in the photoemission spectrum that corresponds to\nthe contribution of the photoelectrons relaxed at the bottom of the InGaN\nconduction band.",
        "positive": "Topological phases and fractional excitations of the exciton condensate\n  in a special class of bilayer systems: We study the exciton condensate in zero temperature limit in a special class\nof electron-hole bilayer systems adjacent to insulating ferromagnetic films.\nWith the self-consistent mean-field approximation, we find that the Rashba\nspin-orbit interaction in the electron and hole layers can induce the p \\pm ip\nor p pairing states depending on the different magnetization of the overlapped\nferromagnetic films. Correspondingly, the topologically nontrivial or trivial\nphases emerge. Furthermore, in the topologically nontrivial phase, the\nquasiparticle excitations of the U(1) vortex are attached to fractional quantum\nnumbers and obey Abelian statistics."
    },
    {
        "anchor": "Ideal refocusing of an optically active spin qubit under strong\n  hyperfine interactions: Combining highly coherent spin control with efficient light-matter coupling\noffers great opportunities for quantum communication and networks, as well as\nquantum computing. Optically active semiconductor quantum dots have\nunparalleled photonic properties, but also modest spin coherence limited by\ntheir resident nuclei. Here, we demonstrate that eliminating strain\ninhomogeneity using lattice-matched GaAs-AlGaAs quantum dot devices prolongs\nthe electron spin coherence by nearly two orders of magnitude, beyond 0.113(3)\nms. To do this, we leverage the 99.30(5)% fidelity of our optical pi-pulse\ngates to implement dynamical decoupling. We vary the number of decoupling\npulses up to N = 81 and find a coherence time scaling of N^{0.75(2)}. This\nscaling manifests an ideal refocusing of strong interactions between the\nelectron and the nuclear-spin ensemble, holding the promise of lifetime-limited\nspin coherence. Our findings demonstrate that the most punishing material\nscience challenge for such quantum-dot devices has a remedy, and constitute the\nbasis for highly coherent spin-photon interfaces.",
        "positive": "Robustness of the optical-conductivity sum rule in Bilayer Graphene: We calculate the optical sum associated with the in-plane conductivity of a\ngraphene bilayer. A bilayer asymmetry gap generated in a field-effect device\ncan split apart valence and conduction bands, which otherwise would meet at two\nK points in the Brillouin zone. In this way one can go from a compensated\nsemimetal to a semiconductor with a tunable gap. However, the sum rule turns\nout to be 'protected' against the opening of this semiconducting gap, in\ncontrast to the large variations observed in other systems where the gap is\ninduced by strong correlation effects."
    },
    {
        "anchor": "Electron spin contrast of Purcell-enhanced nitrogen-vacancy ensembles in\n  nanodiamonds: Nitrogen-vacancy centers in diamond allow for coherent spin state\nmanipulation at room temperature, which could bring dramatic advances to\nnanoscale sensing and quantum information technology. We introduce a novel\nmethod for the optical measurement of the spin contrast in dense\nnitrogen-vacancy (NV) ensembles. This method brings a new insight into the\ninterplay between the spin contrast and fluorescence lifetime. We show that for\nimproving the spin readout sensitivity in NV ensembles, one should aim at\nmodifying the far field radiation pattern rather than enhancing the emission\nrate.",
        "positive": "Fast spin dynamics in hexagonal arrays of Fe atoms on metallic surface: Understanding the nature of magnetic interactions in ultra-small magnetic\nensembles and their intrinsic properties is vital to uncover the dynamics\ntherein. In this study we reveal the spin dynamics of hexagonally arranged Fe\natoms on metallic surface that are triggered by magnetic pulse. The switching\nprocess among various spin configurations and their relative magnetic order is\ntuned by the amplitude and duration of the magnetic pulse. Even more we observe\na parity effect in the switching time as the size of the cluster varies in\nwhich even number of Fe atoms shows faster dynamics. The changes in the\nmultistable magnetic states and switching times are explained by using the\nrelaxation of the exchange and anisotropy energies in time."
    },
    {
        "anchor": "Terahertz Coherent Control of a Landau-Quantized Two-Dimensional\n  Electron Gas: We demonstrate coherent control of cyclotron resonance (CR) in a\ntwo-dimensional electron gas (2DEG). We use a sequence of terahertz pulses to\ncontrol the amplitude of CR oscillations in an arbitrary fashion via\nphase-dependent coherent interactions. We observe a self-interaction effect,\nwhere the 2DEG interacts with the terahertz field emitted by itself within the\ndecoherence time, resulting in a revival and collapse of quantum coherence.\nThese observations are accurately describable using {\\em single-particle}\noptical Bloch equations, showing no signatures of electron-electron\ninteractions, which verifies the validity of Kohn's theorem for CR in the\ncoherent regime.",
        "positive": "Vibrational Instability due to Coherent Tunneling of Electrons: Effects of a coupling between the mechanical vibrations of a quantum dot\nplaced between the two leads of a single electron transistor and coherent\ntunneling of electrons through a single level in the dot has been studied. We\nhave found that for bias voltages exceeding a certain critical value a\ndynamical instability occurs and mechanical vibrations of the dot develop into\na stable limit cycle. The current-voltage characteristics for such a transistor\nwere calculated and they seem to be in a reasonably good agreement with recent\nexperimental results for the single $C_{60}$-molecule transistor by Park et\nal.(Nature {\\bf 407,} (2000) 57)."
    },
    {
        "anchor": "Network structure and dynamics of effective models of non-equilibrium\n  quantum transport: Across all scales of the physical world, dynamical systems can often be\nusefully represented as abstract networks that encode the system's units and\ninter-unit interactions. Understanding how physical rules shape the topological\nstructure of those networks can clarify a system's function and enhance our\nability to design, guide, or control its behavior. In the emerging area of\nquantum network science, a key challenge lies in distinguishing between the\ntopological properties that reflect a system's underlying physics and those\nthat reflect the assumptions of the employed conceptual model. To elucidate and\naddress this challenge, we study networks that represent non-equilibrium\nquantum-electronic transport through quantum antidot devices -- an example of\nan open, mesoscopic quantum system. The network representations correspond to\ntwo different models of internal antidot states: a single-particle,\nnon-interacting model and an effective model for collective excitations\nincluding Coulomb interactions. In these networks, nodes represent accessible\nenergy states and edges represent allowed transitions. We find that both models\nreflect spin conservation rules in the network topology through bipartiteness\nand the presence of only even-length cycles. The models diverge, however, in\nthe minimum length of cycle basis elements, in a manner that depends on whether\nelectrons are considered to be distinguishable. Furthermore, the two models\nreflect spin-conserving relaxation effects differently, as evident in both the\ndegree distribution and the cycle-basis length distribution. Collectively,\nthese observations serve to elucidate the relationship between network\nstructure and physical constraints in quantum-mechanical models. More\ngenerally, our approach underscores the utility of network science in\nunderstanding the dynamics and control of quantum systems.",
        "positive": "Caroli formula in near-field heat transfer between parallel graphene\n  sheets: In this work we conduct a close-up investigation into the nature of\nnear-field heat transfer (NFHT) of two graphene sheets in parallel-plate\ngeometry. We develop a fully microscopic and quantum approach using\nnonequilibrium Green's function method. A Caroli formula for heat flux is\nproposed and numerically verified. We show our near-field-to-black-body heat\nflux ratios generally exhibit $1/d^{\\alpha}$ dependence, with an effective\nexponent $\\alpha \\approx 2.2$, at long distances exceeding 100 nm and up to one\nmicron; in the opposite $d\\rightarrow 0$ limit, the values converge to a range\nwithin an order of magnitude. We justify this feature by noting it is owing to\nthe breakdown of local conductivity theory, which predicts a $1/d$ dependence.\nFurthermore, from the numerical result, we find in addition to thermal\nwavelength, $\\lambda_{th}$, a shorter distance scale $\\sim$ 10 - 100 nm,\ncomparable to the graphene thermal length ($\\hbar v_{F}/k_{B} T$) or Fermi\nwavelength ($k_{F}^{-1}$), marks the transition point between the short- and\nlong-distance transfer behaviors; within that point, relatively large variation\nof heat flux in response to doping level becomes a typical characteristic. The\nemergence of such large variation is tied to relative NFHT contributions from\nthe intra- and inter-band transitions. Beyond that point, scaling of thermal\nflux $\\propto 1/d^{\\alpha}$ can be generally observed."
    },
    {
        "anchor": "Photo-induced tunable Anomalous Hall and Nernst effects in tilted Weyl\n  Semimetals using Floquet theory: In this paper, we discuss the effect of a periodically driving circularly\npolarized laser beam in the high frequency limit, on the band structure and\nthermal transport properties of type-I and type-II Weyl semimetals (WSMs). We\ndevelop the notion of an effective Fermi surface stemming from the\ntime-averaged Floquet Hamiltonian and discuss its effects on the steady-state\noccupation numbers of electrons and holes in the linearized model. In order to\ncompute the transport coefficients averaged over a period of the incident laser\nsource, we employ the Kubo formalism for Floquet states and show that the Kubo\nformula for the conductivity tensor retains its well known form with the\ndifference that the eigenstates and energies are replaced by the Floquet states\nand their quasi-energies. We find that for type-I WSMs the anomalous thermal\nHall conductivity grows quadratically with the amplitude $A_{0}$ of the U(1)\ngauge field for low tilt, while the Nernst conductivity remains unaffected. For\ntype-II WSMs, the Hall conductivity decreases non-linearly with $A_{0}$ due to\nthe contribution from the physical momentum cutoff, required to keep finite\nelectron and hole pocket sizes, and the Nernst conductivity falls of\nlogarithmically with $A_{0}^2$. These results may serve as a diagnostic for\nmaterial characterization and transport parameter tunability in WSMs, which are\ncurrently the subject of a wide range of experiments.",
        "positive": "Current-induced dissociation in molecular junctions beyond the paradigm\n  of vibrational heating: The role of anti-bonding electronic states: The interaction between electronic and nuclear degrees of freedom in\nsingle-molecule junctions is an essential mechanism, which may result in the\ncurrent-induced rupture of chemical bonds. As such, it is fundamental for the\nstability of molecular junctions and for the applicability of molecular\nelectronic devices. In this publication, we study current-induced bond rupture\nin molecular junctions using a numerically exact scheme, which is based on the\nhierarchical quantum master equation (HQME) method in combination with a\ndiscrete variable representation for the nuclear degrees of freedom. Employing\ngeneric models for molecular junctions with dissociative nuclear potentials, we\nidentify distinct mechanisms leading to dissociation, namely the electronic\npopulation of anti-bonding electronic states and the current-induced heating of\nvibrational modes. Our results reveal that the latter plays a negligible role\nwhenever the electronic population of anti-bonding states is energetically\npossible. Consequently, the significance of current-induced heating as a source\nfor dissociation in molecular junctions involving an active anti-bonding state\nis restricted to the non-resonant transport regime, which reframes the\npredominant paradigm in the field of molecular electronics."
    },
    {
        "anchor": "Angular dependence of magnetic properties in Ni nanowire arrays: The angular dependence of the remanence and coercivity of Ni nanowire arrays\nproduced inside the pores of anodic alumina membranes has been studied. By\ncomparing our analytical calculations with our measurements, we conclude that\nthe magnetization reversal in this array is driven by means of the nucleation\nand propagation of a transverse wall. A simple model based on an adapted\nStoner-Wohlfarth model is used to explain the angular dependence of the\ncoercivity.",
        "positive": "Spatial gradient of dynamic nuclear spin polarization induced by\n  breakdown of quantum Hall effect: We studied spatial distribution of dynamic nuclear polarization (DNP) in a\nHall-bar device in a breakdown regime of the quantum Hall effect (QHE). We\ndetected nuclear magnetic resonance (NMR) signals from the polarized nuclear\nspins by measuring the Hall voltage $V_{xy}$ using three pairs of voltage\nprobes attached to the conducting channel of the Hall bar. We find that the\namplitude of the NMR signal depends on the position of the Hall voltage probes\nand that the largest NMR signal is obtained from the pair of probes farthest\nfrom the electron-injecting electrode. Combined with results on pump-and-probe\nmeasurements, we conclude that the DNP induced by QHE breakdown develops along\nthe electron-drift direction."
    },
    {
        "anchor": "Tuning the supercurrent distribution in parallel ballistic graphene\n  Josephson junctions: We report on a ballistic and fully tunable Josephson junction system\nconsisting of two parallel ribbons of graphene in contact with superconducting\nMoRe. By electrostatic gating of the two individual graphene ribbons we gain\ncontrol over the real space distribution of the superconducting current\ndensity, which can be continuously tuned between both ribbons. We extract the\nrespective gate dependent spatial distributions of the real space current\ndensity by employing Fourier- and Hilbert transformations of the magnetic field\ninduced modulation of the critical current. This approach is fast and does not\nrely on a symmetric current profile. It is therefore a universally applicable\ntool, potentially useful for carefully adjusting Josephson junctions.",
        "positive": "Functionalization of edge reconstructed graphene nanoribbons by H and\n  Fe: A density functional study: In this paper, we have studied functionalization of 5-7 edge-reconstructed\ngraphene nanoribbons by ab initio density functional calculations. Our studies\nshow that hydrogenation at the reconstructed edges is favorable in contrast to\nthe case of unreconstructed 6-6 zigzag edges, in agreement with previous\ntheoretical results. Thermodynamical calculations reveal the relative stability\nof single and dihydrogenated edges under different temperatures and chemical\npotential of hydrogen gas. From phonon calculations, we find that the lowest\noptical phonon modes are hardened due to 5-7 edge reconstruction compared to\nthe 6-6 unreconstructed hydrogenated edges. Finally, edge functionalization by\nFe atoms reveals a dimerized Fe chain structure along the edges. The magnetic\nexchange coupling across the edges varies between ferromagnetic and\nantiferromagnetic ones with the variation of the width of the nanoribbons."
    },
    {
        "anchor": "QCAD Simulation and Optimization of Semiconductor Quantum Dots: We present the Quantum Computer Aided Design (QCAD) simulator that targets\nmodeling multi-dimensional quantum devices, particularly silicon multi-quantum\ndots (QDs) developed for quantum bits (qubits). This finite-element simulator\nhas three differentiating features: (i) its core contains nonlinear Poisson,\neffective mass Schrodinger, and Configuration Interaction solvers that have\nmassively parallel capability for high simulation throughput, and can be run\nindividually or combined self-consistently for 1D/2D/3D quantum devices; (ii)\nthe core solvers show superior convergence even at near-zero-Kelvin\ntemperatures, which is critical for modeling quantum computing devices; and\n(iii) it interfaces directly with the full-featured optimization engine Dakota.\nIn this work, we describe the capabilities and implementation of the QCAD\nsimulation tool, and show how it can be used to both analyze existing\nexperimental QD devices through capacitance calculations, and aid in the design\nof few-electron multi-QDs. In particular, we observe that computed capacitances\nare in rough agreement with experiment, and that quantum confinement increases\ncapacitance when the number of electrons is fixed in a quantum dot. Coupling of\nQCAD with the optimizer Dakota allows for rapid identification and improvement\nof device layouts that are likely to exhibit few-electron quantum dot\ncharacteristics.",
        "positive": "Luminescence properties of closely packed organic color centers grafted\n  on a carbon nanotube: We report on the photo-luminescence of pairs of organic color centers in\nsingle-wall carbon nanotubes grafted with 3,5 dichlorobenzene. Using various\ntechniques such as intensity correlations, super-localization microscopy or\nluminescence excitation spectroscopy, we distinguish two pairs of color centers\ngrafted on the same nanotube; the distance between the pairs is on the order of\nseveral hundreds of nanometers. In contrast, by studying the strong temporal\ncorrelations in the spectral diffusion in the framework of photo-induced Stark\neffect, we can estimate the distance within each pair to be of the order of a\nfew nanometers. Finally, the electronic population dynamics is investigated\nusing time-resolved luminescence and saturation measurements, showing a\nbiexponential decay with a fast overall recombination (compatible with a fast\npopulation transfer between the color centers within a pair) and a weak delayed\nrepopulation of the traps possibly due to the diffusion of excitons along the\ntube axis."
    },
    {
        "anchor": "Hard superconducting gap in PbTe nanowires: Semiconductor nanowires coupled to a superconductor provide a powerful\ntestbed for quantum device physics such as Majorana zero modes and gate-tunable\nhybrid qubits. The performance of these quantum devices heavily relies on the\nquality of the induced superconducting gap. A hard gap, evident as vanishing\nsubgap conductance in tunneling spectroscopy, is both necessary and desired.\nPreviously, a hard gap has been achieved and extensively studied in III-V\nsemiconductor nanowires (InAs and InSb). In this study, we present the\nobservation of a hard superconducting gap in PbTe nanowires coupled to a\nsuperconductor Pb. The gap size ($\\Delta$) is $\\sim$ 1 meV (maximally 1.3 meV\nin one device). Additionally, subgap Andreev bound states can also be created\nand controlled through gate tuning. Tuning a device into the open regime can\nreveal Andreev enhancement of the subgap conductance, suggesting a remarkable\ntransparent superconductor-semiconductor interface, with a transparency of\n$\\sim$ 0.96. These results pave the way for diverse superconducting quantum\ndevices based on PbTe nanowires.",
        "positive": "Tunable topological magnon-polaron states and anomalous Hall phenomena\n  in two-dimensional ferromagnetic insulators: We study magnon-polaron hybrid states, mediated by Dzyaloshinskii-Moriya and\nmagnetoelastic interactions, in a two-dimensional ferromagnetic insulator. The\nmagnetic system consists of both in-plane and flexural acoustic and optical\nphonon bands, as well as acoustic and optical magnon bands. Through\nmanipulation of the ground-state magnetization direction using a magnetic\nfield, we demonstrate the tunability of Chern numbers and (spin) Berry\ncurvatures of magnon-polaron hybrid bands. This adjustment subsequently\nmodifies two anomalous Hall responses of the system, namely, thermal Hall and\nspin Nernset signals. Notably, we find that by changing the magnetic field\ndirection in particular directions, it is possible to completely suppress the\nthermal Hall signal while maintaining a finite spin Nernst signal. Our finding\nreveals the intricate interplay between topological and quantum geometrical\nphenomena and magnetic ordering, offering compelling avenues for on-demand\ncontrol over emergent quantum states in condensed matter systems."
    },
    {
        "anchor": "A Two-Field-Scan Harmonic Hall Voltage Analysis For Fast, Accurate\n  Quantification Of Spin-Orbit Torques In Magnetic Heterostructures: The efficiencies of the spin-orbit torques (SOTs) play a key role in the\ndetermination of the power consumption, integration density, and endurance of\nSOT-driven devices. Accurate and time-efficient determination of the SOT\nefficiencies is of great importance not only for evaluating the practical\npotential of SOT devices but also for developing new mechanisms for enhancing\nthe SOT efficiencies. Here, we develop a \"two-field-scan\" harmonic Hall voltage\n(HHV) analysis that collects the second HHV as a function of a swept in-plane\nmagnetic field at 45{\\deg} and 0{\\deg} relative to the excitation current. We\ndemonstrate that this two-field-scan analysis is as accurate as the\nwell-established but time-consuming angle-scan HHV analysis even in the\npresence of considerable thermoelectric effects but takes more than a factor of\n7 less measurement time. We also show that the 3-parameter fit of the HHV data\nfrom a single field scan at 0{\\deg}, which is commonly employed in the\nliterature, is not reliable because the employment of too many free parameters\nin the fitting of the very slowly varying HHV signal allows unrealistic\npseudo-solution and thus erroneous conclusion about the SOT efficiencies.",
        "positive": "Energy spectra of fractional quantum Hall systems in the presence of a\n  valence hole: The energy spectrum of a two-dimensional electron gas (2DEG) in the\nfractional quantum Hall regime interacting with an optically injected valence\nband hole is studied as a function of the filling factor $\\nu$ and the\nseparation $d$ between the electron and hole layers. The response of the 2DEG\nto the hole changes abruptly at $d$ of the order of the magnetic length\n$\\lambda$. At $d<\\lambda$, the hole binds electrons to form neutral ($X$) or\ncharged ($X^-$) excitons, and the photoluminescence (PL) spectrum probes the\nlifetimes and binding energies of these states rather than the original\ncorrelations of the 2DEG. The ``dressed exciton'' picture (in which the\ninteraction between an exciton and the 2DEG was proposed to merely enhance the\nexciton mass) is questioned. Instead, the low energy states are explained in\nterms of Laughlin correlations between the constituent fermions (electrons and\n$X^-$'s) and the formation of two-component incompressible fluid states in the\nelectron--hole plasma. At $d>2\\lambda$, the hole binds up to two Laughlin\nquasielectrons (QE) of the 2DEG to form fractionally charged excitons\n$h$QE$_n$. The previously found ``anyon exciton'' $h$QE$_3$ is shown to be\nunstable at any value of $d$. The critical dependence of the stability of\ndifferent $h$QE$_n$ complexes on the presence of QE's in the 2DEG leads to the\nobserved discontinuity of the PL spectrum at $\\nu={1\\over3}$ or ${2\\over3}$."
    },
    {
        "anchor": "Molecular Dynamics Simulation of Thermal Boundary Conductance Between\n  Carbon Nanotubes and SiO2: We investigate thermal energy coupling between carbon nanotubes (CNTs) and\nSiO2 with non-equilibrium molecular dynamics simulations. The thermal boundary\nconductance (g) per unit CNT length is found to scale proportionally with the\nstrength of the Van der Waals interaction (~X), with CNT diameter (~D), and as\na weak power law of temperature (~T^1/3 between 200-600 K). The thermal\nrelaxation time of a single CNT on SiO2 is independent of diameter, tau ~ 85\nps. With the standard set of parameters g ~ 0.1 W/m/K for a 1.7 nm diameter CNT\nat room temperature. Our results are comparable to, and explain the range of\nexperimental values for CNT-SiO2 thermal coupling from variations in diameter,\ntemperature, or details of the surface interaction strength.",
        "positive": "Interacting holes in Si and Ge double quantum dots: from a multiband\n  approach to an effective-spin picture: The states of two electrons in tunnel-coupled semiconductor quantum dots can\nbe effectively described in terms of a two-spin Hamiltonian with an isotropic\nHeisenberg interaction. A similar description needs to be generalized in the\ncase of holes due to their multiband character and spin-orbit coupling, which\nmixes orbital and spin degrees of freedom, and splits $J=3/2$ and $J = 1/2$\nmultiplets. Here we investigate two-hole states in prototypical coupled Si and\nGe quantum dots via different theoretical approaches. Multiband\n$\\boldsymbol{k}\\cdot\\boldsymbol{p}$ and Configuration-Interaction calculations\nare combined with entanglement measures in order to thoroughly characterize the\ntwo-hole states in terms of band mixing and justify the introduction of an\neffective spin representation, which we analytically derive a from generalized\nHubbard model. We find that, in the weak interdot regime, the ground state and\nfirst excited multiplet of the two-hole system display -- unlike their\nelectronic counterparts -- a high degree of $J$-mixing, even in the limit of\npurely heavy-hole states. The light-hole component additionally induces\n$M$-mixing and a weak coupling between spinors characterized by different\npermutational symmetries."
    },
    {
        "anchor": "Quantum-correlated two-photon transitions to excitons in semiconductor\n  quantum wells: The dependence of the excitonic two-photon absorption on the quantum\ncorrelations (entanglement) of exciting biphotons by a semiconductor quantum\nwell is studied. We show that entangled photon absorption can display very\nunusual features depending on space-time-polarization biphoton parameters and\nabsorber density of states for both bound exciton states as well as for unbound\nelectron-hole pairs. We report on the connection between biphoton entanglement,\nas quantified by the Schmidt number, and absorption by a semiconductor quantum\nwell. Comparison between frequency-anti-correlated, unentangled and\nfrequency-correlated biphoton absorption is addressed. We found that exciton\noscillator strengths are highly increased when photons arrive almost\nsimultaneously in an entangled state. Two-photon-absorption becomes a highly\nsensitive probe of photon quantum correlations when narrow semiconductor\nquantum wells are used as two-photon absorbers.",
        "positive": "Intrinsic Coupling between Current and Domain Wall Motion in (Ga,Mn)As: We consider current-induced domain wall motion and, the reciprocal process,\nmoving domain wall-induced current. The associated Onsager coefficients are\nexpressed in terms of scattering matrices. Uncommonly, in (Ga,Mn)As, the\neffective Gilbert damping coefficient $\\alpha_w$ and the effective out-of-plane\nspin transfer torque parameter $\\beta_w$ are dominated by spin-orbit\ninteraction in combination with scattering off the domain wall, and not\nscattering off extrinsic impurities. Numerical calculations give $\\alpha_w \\sim\n0.01$ and $\\beta_w \\sim 1$ in dirty (Ga,Mn)As. The extraordinary large\n$\\beta_w$ parameter allows experimental detection of current or voltage induced\nby domain wall motion in (Ga,Mn)As."
    },
    {
        "anchor": "Single-shot readout and relaxation of singlet/triplet states in\n  exchange-coupled $^{31}$P electron spins in silicon: We present the experimental observation of a large exchange coupling $J\n\\approx 300$ $\\mu$eV between two $^{31}$P electron spin qubits in silicon. The\nsinglet and triplet states of the coupled spins are monitored in real time by a\nSingle-Electron Transistor, which detects ionization from tunnel-rate-dependent\nprocesses in the coupled spin system, yielding single-shot readout fidelities\nabove 95%. The triplet to singlet relaxation time $T_1 \\approx 4$ ms at zero\nmagnetic field agrees with the theoretical prediction for $J$-coupled $^{31}$P\ndimers in silicon. The time evolution of the 2-electron state populations gives\nfurther insight into the valley-orbit eigenstates of the donor dimer, valley\nselection rules and relaxation rates, and the role of hyperfine interactions.\nThese results pave the way to the realization of 2-qubit quantum logic gates\nwith spins in silicon, and highlight the necessity to adopt gating schemes\ncompatible with weak $J$-coupling strengths.",
        "positive": "Delocalized-localized transition in a semiconductor two-dimensional\n  honeycomb lattice: We report the magneto-transport properties of a two-dimensional electron gas\nin a modulation-doped AlGaAs/GaAs heterostructure subjected to a lateral\npotential with honeycomb geometry. Periodic oscillations of the\nmagneto-resistance and a delocalized-localized transition are shown by applying\na gate voltage. We argue that electrons in such artificial-graphene lattices\noffer a promising approach for the simulation of quantum phases dictated by\nCoulomb interactions."
    },
    {
        "anchor": "Photoluminescence from voids created by femtosecond laser pulses inside\n  cubic-BN: Photoluminescence (PL) from femtosecond laser modified regions inside\ncubic-boron nitride (c-BN) was measured under UV and visible light excitation.\nBright PL at the red spectral range was observed, with a typical excited state\nlifetime of $\\sim 4$~ns. Sharp emission lines are consistent with PL of\nintrinsic vibronic defects linked to the nitrogen vacancy formation (via\nFrenkel pair) observed earlier in high energy electron irradiated and\nion-implanted c-BN. These, formerly known as the radiation centers, RC1, RC2,\nand RC3 have been identified at the locus of the voids formed by single\nfs-laser pulse. The method is promising to engineer color centers in c-BN for\nphotonic applications.",
        "positive": "Contact resistance at planar metal contacts on bilayer graphene and\n  effects of molecular insertion layers: The possible origins of metal-bilayer graphene (BLG) contact resistance are\ninvestigated by taking into consideration the bandgap formed by interfacial\ncharge transfer at the metal contacts. Our results show that a charge injection\nbarrier (Schottky barrier) does not contribute to the contact resistance\nbecause the BLG under the contacts is always degenerately doped. We also showed\nthat the contact-doping-induced increase in the density of states (DOS) of BLG\nunder the metal contacts decreases the contact resistance owing to enhanced\ncharge carrier tunnelling at the contacts. The contact doping can be enhanced\nby inserting molecular dopant layers into the metal contacts. However, carrier\ntunnelling through the insertion layer increases the contact resistance, and\nthus, alternative device structures should be employed. Finally, we showed that\nthe inter-band transport by variable range hopping via in-gap states is the\nlargest contributor to contact resistance when the carrier type of the gated\nchannel is opposite to the contact doping carrier type. This indicates that the\nstrategy of contact resistance reduction by the contact-doping-induced increase\nin the DOS is effective only for a single channel transport branch (n- or\np-type) depending on the contact doping carrier type."
    },
    {
        "anchor": "Hot-electron Effect in A Cylindrical Nanoshell: A general expression for calculating the thermal power transferring from\n3-dimensional electron to any D-dimensional phonon subsystem is derived in this\npaper. Electron-phonon coupling in a free suspended cylindrical nanoshell is\nstudied, in which acoustic phonons are confined to quasi-one dimension but\nelectrons behave three-dimensionally. The temperature dependence of the thermal\npower is obtained analytically, and the low-temperature crossover from the\n$T^{3}$ to $T^{3}/(1-\\nu^2)+9\\gamma T^4/[T^*(1-\\nu^2)^{3/2}]$ dependence is\nalso observed. The corresponding quantities are estimated for the material\nparameters from a metallic nanotube.",
        "positive": "Interface symmetry and spin control in topological\n  insulator-semiconductor heterostructures: Heterostructures combining topological and non-topological materials\nconstitute the next frontier in the effort to incorporate topological\ninsulators (TIs) into functional electronic devices. We show that the\nproperties of the interface states appearing at the planar boundary between a\ntopologically-trivial semiconductor (SE) and a TI are controlled by the\nsymmetry of the interface. In contrast to the well-studied helical Dirac\nsurface states, SE-TI interface states exhibit elliptical contours of constant\nenergy and complex spin textures with broken helicity. We derive a general\neffective Hamiltonian for SE-TI junctions, and propose experimental signatures\nsuch as an out of plane spin accumulation under a transport current and the\nopening of a spectral gap that depends on the direction of an applied in-plane\nmagnetic field."
    },
    {
        "anchor": "Quantum synchronization and transresistance quantization in\n  superconducting devices: We show theoretically the possibility of quantum synchronization of Josephson\nand Bloch oscillations in a superconducting device. One needs an $LC$\noscillator to achieve exponentially small rate of synchronization errors. The\nsynchronization leads to quantization of transresistance similar to that in\n(Fractional) Quantum Hall Effect.",
        "positive": "Switching behaviour of stilbene molecular device: a first-principles\n  study: The switching behaviour of stilbene molecular system (SMS) device is\ninvestigated with the help of non-equilibrium Green's function (NEGF) approach\nusing first principles calculation. The transmission spectrum of cis-isomers\nconfirmed that more electrons are transferred across the SMS-device using\noptical excitation by the spin of C$=$C bond by torsion angle\n$(\\theta=180^\\circ)$. The current-voltage characteristics show the lower\nmagnitude of current for trans-stilbene and higher magnitude of current for\ncis-stilbene for an externally applied bias voltage. The outcome of the\nproposed work suggests that cis and trans-stilbene molecular device can be used\nas a switch."
    },
    {
        "anchor": "The magnetic anisotropy of individually addressed spin states: Controlling magnetic anisotropy is a key requirement for the fundamental\nunderstanding of molecular magnetism and is a prerequisite for numerous\napplications in magnetic storage, spintronics, and all-spin logic devices. In\norder to address the question of molecular magnetic anisotropy experimentally,\nwe have synthesized single-crystals of a molecular spin system containing four\nantiferromagnetically coupled s = 5/2 manganese(II) ions. Using low-temperature\ncantilever magnetometry, we demonstrate the selective population of the S = 0,\n1, . . . , 10 spin states upon application of magnetic fields up to 33 T and\nmap the magnetic anisotropy of each of these states. We observe a strong\ndependence of the shape and size of the magnetic anisotropy on the populated\nspin states, and, in particular, reveal an anisotropy reversal upon going from\nthe lowest to the highest spin-state.",
        "positive": "Longitudinal relaxation and thermoactivation of quantum superparamagnets: The relaxation mechanisms of a quantum nanomagnet are discussed in the frame\nof linear response theory. We use a spin Hamiltonian with a uniaxial potential\nbarrier plus a Zeeman term. The spin, having arbitrary $S$, is coupled to a\nbosonic environment. From the eigenstructure of the relaxation matrix, we\nidentify two main mechanisms, namely, thermal activation over the barrier, with\na time scale $\\eival_1^{-1}$, and a faster dynamics inside the potential wells,\nwith characteristic time $\\eivalW^{-1}$. This allows to introduce a simple\nanalytical formula for the response, which agrees well with the exact numerical\nresults, and cover experiments even under moderate to strong fields in the\nsuperparamagnetic range. In passing, we generalize known classical results for\na number of quantities (e.g., integral relaxation times, initial decay time,\nKramers rate), results that are recovered in the limit $S\\to\\infty$."
    },
    {
        "anchor": "Electronic transport of bilayer graphene with asymmetry line defects: In this paper, we study the quantum properties of a bilayer graphene with\n(asymmetry) line defects. The localized states are found around the line\ndefects. Thus, the line defects on one certain layer of the bilayer graphene\ncan lead to an electric transport channel. By adding a bias potential along the\ndirection of the line defects, we calculate the electric conductivity of\nbilayer graphene with line defects using Landauer-B\\\"{u}ttiker theory, and show\nthat the channel affects the electric conductivity remarkably by comparing the\nresults with those in a perfect bilayer graphene. This one-dimensional line\nelectric channel has the potential to be applied in the nanotechnology\nengineering.",
        "positive": "Some Exactly-Solvable Quantum Problems and their Applications to Hetero-\n  and Nano-Structures with Nontrivial Topology: Analytical calculations based on a Landau Level (LL) picture are reported for\na many-electron system moving in an interface (with a finite-width Quantum Well\n(QW)) and in the presence of an external perpendicular magnetic field. They\nlead to a sequence of previously unnoticed singular features in global\nmagnetization and magnetic susceptibility that give rise to nontrivial\ncorrections to the standard de Haas-van Alphen periods. Additional features due\nto Zeeman splitting are also reported (such as new energy minima that originate\nfrom the interplay of QW, Zeeman and LL Physics). A corresponding calculation\nin a Composite Fermion picture leads to new predictions on magnetic response\nproperties of a fully-interacting electron liquid in a finite-width interface.\nExact solutions for the energetics of a fully three-dimensional system of many\nnoninteracting electrons in a magnetic field are also presented (a system\nmostly discussed in astrophysical applications), with Hurwitz zeta functions\nplaying an important role on thermodynamic properties. Finally, exact solutions\nfor the energetics of an electron gas on a cylindrical surface (and in the\npresence of an Aharonov-Bohm flux threading the cylinder) are presented, in two\ncases: when the radius R of the cylinder is microscopically small and the\nlength of the cylinder is macrocopically large (an electron gas nanotube), and\nvice versa. Inclusion in the above systems of a radial magnetic field and also\nof Zeeman splitting gives rise to curvature-induced spin-orbit coupling, that\nleads to interesting behaviors that can also be dealt with analytically. A\ncorresponding SU(2) formulation and a number of diagonalization results for the\nenergy of such curved systems have, in the limit of vanishing curvature, the\ncorrect behaviors (namely, the standard spin-Physics in flat space, that is\ndecoupled from the standard orbital-Physics of Landau Levels)."
    },
    {
        "anchor": "Symmetry and topology in antiferromagnetic spintronics: Antiferromagnetic spintronics focuses on investigating and using\nantiferromagnets as active elements in spintronics structures. Last decade\nadvances in relativistic spintronics led to the discovery of the staggered,\ncurrent-induced field in antiferromagnets. The corresponding N\\'{e}el\nspin-orbit torque allowed for efficient electrical switching of\nantiferromagnetic moments and, in combination with electrical readout, for the\ndemonstration of experimental antiferromagnetic memory devices. In parallel,\nthe anomalous Hall effect was predicted and subsequently observed in\nantiferromagnets. A new field of spintronics based on antiferromagnets has\nemerged. We will focus here on the introduction into the most significant\ndiscoveries which shaped the field together with a more recent spin-off\nfocusing on combining antiferromagnetic spintronics with topological effects,\nsuch as antiferromagnetic topological semimetals and insulators, and the\ninterplay of antiferromagnetism, topology, and superconductivity in\nheterostructures.",
        "positive": "Quasiexcitons in Incompressible Quantum Liquids: Photoluminescence (PL) has been used to study two-dimensional incompressible\nelectron liquids in high magnetic fields for nearly two decades. However, some\nof the observed anomalies coincident with the fractional quantum Hall effect\nare still unexplained. We show that emission in these systems occurs from\nfractionally charged \"quasiexciton\" states formed from trions correlated with\nthe surrounding electrons. Their binding and recombination depend on the state\nof both the electron liquid and the involved trion, predicting discontinuities\nin PL and sensitivity to sample parameters."
    },
    {
        "anchor": "Skyrmion Dynamics and Topological Sorting on Periodic Obstacle Arrays: We examine skyrmions under a dc drive interacting with a square array of\nobstacles for varied obstacle size and damping. When the drive is applied in a\nfixed direction, we find that the skyrmions are initially guided in the drive\ndirection but also move transverse to the drive due to the Magnus force. The\nskyrmion Hall angle, which indicates the difference between the skyrmion\ndirection of motion and the drive direction, increases with drive in a series\nof quantized steps as a result of the locking of the skyrmion motion to\nspecific symmetry directions of the obstacle array. On these steps, the\nskyrmions collide with an integer number of obstacles to create a periodic\nmotion. The transitions between the different locking steps are associated with\njumps or dips in the velocity-force curves. In some regimes, the skyrmion Hall\nangle is actually higher than the intrinsic skyrmion Hall angle that would\nappear in the absence of obstacles. In the limit of zero damping, the skyrmion\nHall angle is 90$^\\circ$, and we find that it decreases as the damping\nincreases. For multiple interacting skyrmion species in the collective regime,\nwe find jammed behavior at low drives where the different skyrmion species are\nstrongly coupled and move in the same direction. As the drive increases, the\nspecies decouple and each can lock to a different symmetry direction of the\nobstacle lattice, making it possible to perform topological sorting in analogy\nto the particle sorting methods used to fractionate different species of\ncolloidal particles moving over two-dimensional obstacle arrays.",
        "positive": "Direct Measurement of the Exciton Binding Energy and Effective Masses\n  for Charge carriers in an Organic-Inorganic Tri-halide Perovskite: Solar cells based on the organic-inorganic tri-halide perovskite family of\nmaterials have shown remarkable progress recently, offering the prospect of\nlow-cost solar energy from devices that are very simple to process. Fundamental\nto understanding the operation of these devices is the exciton binding energy,\nwhich has proved both difficult to measure directly and controversial. We\ndemonstrate that by using very high magnetic fields it is possible to make an\naccurate and direct spectroscopic measurement of the exciton binding energy,\nwhich we find to be only 16 meV at low temperatures, over three times smaller\nthan has been previously assumed. In the room temperature phase we show that\nthe binding energy falls to even smaller values of only a few\nmillielectronvolts, which explains their excellent device performance due to\nspontaneous free carrier generation following light absorption. Additionally,\nwe determine the excitonic reduced effective mass to be 0.104me (where me is\nthe electron mass), significantly smaller than previously estimated\nexperimentally but in good agreement with recent calculations. Our work\nprovides crucial information about the photophysics of these materials, which\nwill in turn allow improved optoelectronic device operation and better\nunderstanding of their electronic properties."
    },
    {
        "anchor": "Discrete solitons in graphene metamaterials: We study nonlinear properties of multilayer metamaterials created by graphene\nsheets separated by dielectric layers. We demonstrate that such structures can\nsupport localized nonlinear modes described by the discrete nonlinear\nSchr\\\"{o}dinger equation and that its solutions are associated with stable\ndiscrete plasmon solitons. We also analyze the nonlinear surface modes in\ntruncated graphene metamaterials being a nonlinear analog of surface Tamm\nstates.",
        "positive": "Thomas precession, persistent spin currents and quantum forces: We consider T-invariant spin currents induced by spin-orbit interactions\nwhich originate from the confined motion of spin carriers in nanostructures.\nThe resulting Thomas spin precession is a fundamental and purely kinematic\nrelativistic effect occurring when the acceleration of carriers is not parallel\nto their velocity. In the case, where the carriers (e.g. electrons) have\nmagnetic moment the forces due to the electric field of the spin current can,\nin certain conditions, exceed the van der Waals-Casimir forces by several\norders of magnitude. We also discuss a possible experimental set-up tailored to\nuse these forces for checking the existence of a nonzero anomalous magnetic\nmoment of the photon."
    },
    {
        "anchor": "Chiral plasmon in gapped Dirac systems: We study the electromagnetic response and surface electromagnetic modes in a\ngeneric gapped Dirac material under pumping with circularly polarized light.\nThe valley imbalance due to pumping leads to a net Berry curvature, giving rise\nto a finite transverse conductivity. We discuss the appearance of nonreciprocal\nchiral edge modes, their hybridization and waveguiding in a nanoribbon\ngeometry, and giant polarization rotation in nanoribbon arrays.",
        "positive": "Reply on the comment on the paper \"Superconducting transition in Nb\n  nanowires fabricated using focused ion beam\": In this communication we present our response to the recent comment of A.\nEngel regarding our paper on FIB- fabricated Nb nanowires (see Vol. 20 (2009)\nPag. 465302). After further analysis and additional experimental evidence, we\nconclude that our interpretation of the experimental results in light of QPS\ntheory is still valid when compared with the alternative proximity-based model\nas proposed by A. Engel."
    },
    {
        "anchor": "How spin-orbit interaction can cause electronic shot noise: The shot noise in the electrical current through a ballistic chaotic quantum\ndot with N-channel point contacts is suppressed for N --> infinity, because of\nthe transition from stochastic scattering of quantum wave packets to\ndeterministic dynamics of classical trajectories. The dynamics of the electron\nspin remains quantum mechanical in this transition, and can affect the\nelectrical current via spin-orbit interaction. We explain how the role of the\nchannel number N in determining the shot noise is taken over by the ratio\nl_{so}/lambda_F of spin precession length l_{so} and Fermi wave length\nlambda_F, and present computer simulations in a two-dimensional billiard\ngeometry (Lyapunov exponent alpha, mean dwell time tau_{dwell}, point contact\nwidth W) to demonstrate the scaling (lambda_F/l_{so})^{1/alpha tau_{dwell}} of\nthe shot noise in the regime lambda_F << l_{so} << W.",
        "positive": "Dirac electrons in the presence of matrix potential barrier: application\n  to graphene and topological insulators: Scattering of a 2D Dirac electrons on a rectangular matrix potential barrier\nis considered using the formalism of spinor transfer matrices. It is shown, in\nparticular, that in the absence of the mass term, the Klein tunneling is not\nnecessarily suppressed but occurs at oblique incidence. The formalism is\napplied to studying waveguiding modes of the barrier, which are supported by\nthe edge and bulk states. The condition of existence of the uni-directionality\nproperty is found. We show that the band of edge states is always finite with\nmassless excitations, while the spectrum of the bulk states, depending on\nparameters of the barrier, may consist of the infinite or finite band with\nboth, massive and massless, low-energy excitations. The effect of the Zeeman\nterm is considered and the condition of appearance of two distinct energy\ndependent directions corresponding to the Klein tunneling is found."
    },
    {
        "anchor": "Imaging Dirac fermions flow through a circular Veselago lens: Graphene charge carriers behave as relativistic massless fermions, thereby\nexhibiting a variety of counter-intuitive behaviors. In particular, at p-n\njunctions, they behave as photons encountering a negative index media,\ntherefore experiencing a peculiar refraction known as Veselago lensing.\nHowever, the way Dirac fermions flow through a Veselago lens remains largely\nunexplored experimentally. Here, a novel approach to create a movable and\ntunable circular p-n junction in graphene is proposed, using the polarized tip\nof a scanning gate microscope. Scanning the tip in the vicinity of a graphene\nconstriction while recording the device conductance yields images related to\nthe electron flow through a circular Veselago lens, revealing a high current\ndensity in the lens core, as well as two low current density zones along\ntransport axis. Tight-binding simulations reveal the crucial role of the p-n\njunction smoothness on these phenomena. The present research adds new\ndimensions in the control and understanding of Dirac fermions optical elements,\na prerequisite to engineer relativistic electron optics devices.",
        "positive": "Theory for transport through a single magnetic molecule: Endohedral\n  N@C60: We consider transport through a single N@C60 molecule, weakly coupled to\nmetallic leads. Employing a density-matrix formalism we derive rate equations\nfor the occupation probabilities of many-particle states of the molecule. We\ncalculate the current-voltage characteristics and the differential conductance\nfor N@C60 in a break junction. Our results reveal Coulomb-blockade behavior as\nwell as a fine structure of the Coulomb-blockade peaks due to the exchange\ncoupling of the C60 spin to the spin of the encapsulated nitrogen atom."
    },
    {
        "anchor": "Magnetoresistive detection of perpendicular switching in a magnetic\n  insulator: Spintronics offers promising routes for efficient memory, logic, and\ncomputing technologies. The central challenge in spintronics is electrically\nmanipulating and detecting magnetic states in devices. The electrical control\nof magnetization via spin-orbit torques is effective in both conducting and\ninsulating magnetic layers. However, the electrical readout of magnetization in\nthe latter is inherently difficult, limiting its use in practical applications.\nHere, we demonstrate magnetoresistive detection of perpendicular magnetization\nreversal in an electrically insulating ferrimagnet, terbium iron garnet (TbIG).\nTo do so, we use TbIG|Cu|TbCo, where TbCo is a conducting ferrimagnet and\nserves as the reference layer, and Cu is a nonmagnetic spacer. Current\ninjection through Cu|TbCo allows us to detect the magnetization reversal of\nTbIG with a simple resistance readout during an external magnetic field sweep.\nBy examining the effect of measurement temperature, TbCo composition, and Cu\nthickness on the sign and amplitude of the magnetoresistance, we conclude that\nthe spin-dependent electron scattering at the TbIG|Cu interface is the\nunderlying cause. Technologically-feasible magnetoresistive detection of\nperpendicular switching in a ferrimagnetic garnet is a breakthrough, as it\nopens broad avenues for novel insulating spintronic devices and concepts.",
        "positive": "Gapless excitations in the Haldane-Rezayi state: The thin torus limit: We study the thin torus limit of the Haldane-Rezayi state. Eight of the ten\nground states are found to assume a simple product form in this limit, as is\nknown to be the case for many other quantum Hall trial wave functions. The two\nremaining states have a somewhat unusual thin torus limit, where a \"broken\"\npair of defects forming a singlet is completely delocalized. We derive these\nlimits from the wave functions on the cylinder, and deduce the dominant matrix\nelements of the thin torus hollow-core Hamiltonians. We find that there are\ngapless excitations in the thin torus limit. This is in agreement with the\nexpectation that local Hamiltonians stabilizing wave functions associated with\nnon-unitary conformal field theories are gapless. We also use the thin torus\nanalysis to obtain explicit counting formulas for the zero modes of the\nhollow-core Hamiltonian on the torus, as well as for the parent Hamiltonians of\nseveral other paired and related quantum Hall states."
    },
    {
        "anchor": "Comment on \"Absence of Compressible Edge Channel Rings in Quantum\n  Antidots\": In a recent article, Karakurt et al. [I. Karakurt et al., Phys. Rev. Lett.\n89, 226803 (2002)] reported the absence of compressible regions around antidots\nin the quantum Hall regime. We wish to point out a significant flaw in their\nanalysis, which invalidates their claim.",
        "positive": "Dynamical Coulomb blockade theory of plasmon-mediated light emission\n  from a tunnel junction: Inelastic tunneling of electrons can generate the emission of photons with\nenergies intuitively limited by the applied bias voltage. However, experiments\nindicate that more complex processes involving the interaction of electrons\nwith plasmon polaritons lead to photon emission with overbias energies. We\nrecently proposed a model of this observation in Phys. Rev. Lett. \\textbf{113},\n066801 (2014), in analogy to the dynamical Coulomb blockade, originally\ndeveloped for treating the electromagnetic environment in mesoscopic circuits.\nThis model describes the correlated tunneling of two electrons interacting with\na local plasmon-polariton mode, represented by a resonant circuit, and shows\nthat the overbias emission is due to the non-Gaussian fluctuations. Here we\nextend our model to study the overbias emission at finite temperature. We find\nthat the thermal smearing strongly masks the overbias emission. Hence, the\ndetection of the correlated tunneling processes requires temperatures $k_BT$\nmuch lower than the bias energy $eV$ and the plasmon energy $\\hbar\\omega_0$, a\ncondition which is fortunately realized experimentally."
    },
    {
        "anchor": "Entanglement dynamics and Mollow nonuplets between two coupled quantum\n  dots in a nanowire photonic crystal system: We introduce a nanowire-based photonic crystal waveguide system capable of\ncontrollably mediating the photon coupling between two quantum dots which are\nmacroscopically separated. Using a rigorous Green-function-based master\nequation approach, our two-dot system is shown to provide a wide range of\ninteresting quantum regimes. In particular, we demonstrate the formation of\nlong-lived entangled states and study the resonance fluorescence spectrum which\ncontains clear signatures of the coupled quantum dot pair. Depending upon the\noperating frequency, one can obtain a modified Mollow triplet spectrum or a\nMollow nonuplet, namely a spectrum with nine spectral peaks. These multiple\npeaks are explained in the context of photon-exchange-mediated dressed states.\nResults are robust with respect to scattering loss, and spatial filtering via\npropagation allows for each quantum dot's emission to be observed individually.",
        "positive": "Application of algebraic combinatorics to finite spin systems with\n  dihedral symmetry: Properties of a given symmetry group G are very important in investigation of\na physical system invariant under its action. In the case of finite spin\nsystems (magnetic rings, some planar macromolecules) the symmetry group is\nisomorphic with the dihedral group D_N. In this paper group-theoretical\n`parameters' of such groups are determined, especially decompositions of\ntransitive representations into irreducible ones and double cosets. These\nresults are necessary to construct matrix elements of any operator commuting\nwith G in an efficient way. The approach proposed can be usefull in many\nbranches of physics, but here it is applied to finite spin systems, which serve\nas models for mesoscopic magnets."
    },
    {
        "anchor": "Spin current generation from Coulomb-Rashba interaction in semiconductor\n  bilayers: Electrons in double-layer semiconductor heterostructures experience a special\ntype of spin-orbit interaction which arises in each layer from the\nperpendicular component of the Coulomb electric field created by electron\ndensity fluctuations in the other layer. We show that this interaction, acting\nin combination with the usual spin-orbit interaction, can generate a spin\ncurrent in one layer when a charge current is driven in the other. This effect\nis symmetry-wise distinct from the spin Hall drag. The spin current is not, in\ngeneral, perpendicular to the drive current.",
        "positive": "Plasma-enhanced chemical vapor deposition of amorphous Si on graphene: Plasma-enhanced chemical vapor deposition of thin a-Si:H layers on\ntransferred large area graphene is investigated. Radio frequency (RF, 13.56\nMHz) and very high frequency (VHF, 140 MHz) plasma processes are compared. Both\nmethods provide conformal coating of graphene with Si layers as thin as 20 nm\nwithout any additional seed layer. The RF plasma process results in\namorphization of the graphene layer. In contrast, the VHF process keeps the\nhigh crystalline quality of the graphene layer almost intact. Correlation\nanalysis of Raman 2D and G band positions indicates that Si deposition induces\nreduction of the initial doping in graphene and an increase of compressive\nstrain. Upon rapid thermal annealing the amorphous Si layer undergoes\ndehydrogenation and transformation into a polycrystalline film whereby a high\ncrystalline quality of graphene is preserved."
    },
    {
        "anchor": "NdCeCuO - NdCeO boundary and resistive switchings in mesoscopic\n  structures on base of epitaxial NdCeCuO films: Reverse and stable bipolar resistive switching effect was observed in planar\nNdCeCuO - NdCeO - Ag heterostructures. It was shown that the current voltage\ncharactereriscs of the BRSE observed has a diode character. Simulations were\nused to consider the influence of the nonuniform distribution of an electric\nfield at the interface of a heterojunction on the effect of bipolar resistive\nswitching in investigated structures. The inhomogeneous distribution of the\nelectric field near the contact edge creates regions of higher electric field\nstrength which, in turn, stimulates motion and redistribution of defects,\nchanges of the resistive properties of the whole structure and formation of a\npercolation channel.",
        "positive": "Purcell factor for plasmon-enhanced metal photoluminescence: We present an analytical model for plasmonic enhancement of metal\nphotoluminescence (MPL) in metal nanostructures with characteristic size below\nthe diffraction limit. In such systems, the primary mechanism of MPL\nenhancement is excitation of localized surface plasmons (LSP) by recombining\ncarriers followed by a photon emission due to LSP radiative decay. For\nplasmonic nanostructures of arbitrary shape, we obtain a universal expression\nfor MPL Purcell factor that describes the plasmonic enhancement of MPL in terms\nof metal dielectric function, LSP frequency, and the system volume. We find\nthat the lineshape of MPL spectrum is affected by the interference between\ndirect carrier recombination processes and those mediated by plasmonic antenna\nwhich leads to a blueshift of MPL spectral band relative to LSP resonance in\nscattering spectra observed in numerous experiments."
    },
    {
        "anchor": "Compression-induced crossovers for the ground-state of classical dipole\n  lattices on a M\u00f6bius strip: We explore the ground state properties of a lattice of classical dipoles\nspanned on the surface of a M\\\"{o}bius strip. The dipole equilibrium\nconfigurations depend significantly on the geometrical parameters of the\nM\\\"{o}bius strip, as well as on the lattice dimensions. As a result of the\nvariable dipole spacing on the curved surface of the M\\\"{o}bius strip, the\nground state can consist of multiple domains with different dipole orientations\nwhich are separated by domain walls. We analyze in particular the dependence of\nthe ground state dipole configuration on the width of the M\\\"{o}bius strip and\nhighlight two crossovers in the ground state that can be correspondingly tuned.\nA first crossover changes the dipole lattice from a phase which resists\ncompression to a phase that favors it. The second crossover leads to an\nexchange of the topological properties of the two involved domains. We conclude\nwith a brief summary and an outlook on more complex topologically intricate\nsurfaces.",
        "positive": "Analytical approach to swift nonleaky entangling gates in\n  superconducting qubits: We develop schemes for designing pulses that implement fast and precise\nentangling quantum gates in superconducting qubit systems despite the presence\nof nearby harmful transitions. Our approach is based on purposely involving the\nnearest harmful transition in the quantum evolution instead of trying to avoid\nit. Using analytical tools, we design simple microwave control fields that\nimplement maximally entangling gates with fidelities exceeding 99% in times as\nlow as 40 ns. We demonstrate our approach in a two-qubit circuit QED system by\ndesigning the two most important quantum entangling gates: a conditional-NOT\ngate and a conditional-Z gate. Our results constitute an important step toward\novercoming the problem of spectral crowding, one of the primary challenges in\ncontrolling multi-qubit systems."
    },
    {
        "anchor": "HofstadterTools: A Python package for analyzing the Hofstadter model: The Hofstadter model successfully describes the behavior of non-interacting\nquantum particles hopping on a lattice coupled to a gauge field, and hence is\nubiquitous in many fields of research, including condensed matter, optical, and\natomic physics. Motivated by this, we introduce HofstadterTools\n(https://hofstadter.tools), a Python package that can be used to analyze the\nenergy spectrum of a generalized Hofstadter model, with any combination of\nhoppings on any regular Euclidean lattice. The package can be applied to\ncompute key properties of the band structure, such as quantum geometry and\ntopology, as well as plot Hofstadter butterflies and Wannier diagrams that are\ncolored according to their Chern numbers.",
        "positive": "Overview of Beyond-CMOS Devices and A Uniform Methodology for Their\n  Benchmarking: Multiple logic devices are presently under study within the Nanoelectronic\nResearch Initiative (NRI) to carry the development of integrated circuits\nbeyond the CMOS roadmap. Structure and operational principles of these devices\nare described. Theories used for benchmarking these devices are overviewed, and\na general methodology is described for consistent estimates of the circuit\narea, switching time and energy. The results of the comparison of the NRI logic\ndevices using these benchmarks are presented."
    },
    {
        "anchor": "Theory of Current-Induced Breakdown of the Quantum Hall Effect: By studying the quantum Hall effect of stationary states with high values of\ninjected current using a von Neumann lattice representation, we found that\nbroadening of extended state bands due to a Hall electric field occurs and\ncauses the breakdown of the quantum Hall effect. The Hall conductance agrees\nwith a topological invariant that is quantized exactly below a critical field\nand is not quantized above a critical field. The critical field is proportional\nto $B^{3/2}$ and is enhanced substantially if the extended states occupy a\nsmall fraction of the system.",
        "positive": "Disentangling the exchange coupling of entangled donors in the Si\n  quantum computer architecture: We develop a theory for micro-Raman scattering by single and coupled\ntwo-donor states in silicon. We find the Raman spectra to have significant\ndependence on the donor exchange splitting and the relative spatial positions\nof the two donor sites. In particular, we establish a strong correlation\nbetween the temperature dependence of the Raman peak intensity and the\ninterdonor exchange coupling. Micro-Raman scattering can therefore potentially\nbecome a powerful tool to measure interqubit coupling in the development of a\nSi quantum computer architecture."
    },
    {
        "anchor": "Radiofrequency driving of coherent electron spin dynamics in $n$-GaAs\n  detected by Faraday rotation: We suggest a new pump-probe method for studying semiconductor spin dynamics\nbased on pumping of carrier spins by a pulse of oscillating radiofrequency (rf)\nmagnetic field and probing by measuring the Faraday rotation of a short laser\npulse. We demonstrate this technique on $n$-GaAs and observe the onset and\ndecay of coherent spin precession during and after the course of rf pulse\nexcitation. We show that the rf field resonantly addresses the electron spins\nwith Larmor frequencies close to that of the rf field. This opens the\nopportunity to determine the homogeneous spin coherence time $T_2$, that is\ninaccessible directly in standard all-optical pump-probe experiments.",
        "positive": "Charged grain boundaries and carrier recombination in polycrystalline\n  thin film solar cells: We present analytical relations for the dark recombination current of a\n$pn^+$ junction with positively charged columnar grain boundaries in the high\ndefect density regime. We consider two defect state configurations relevant for\npositively charged grain boundaries: a single donor state and a continuum of\nboth acceptors and donors. Compared to a continuum of acceptor+donor states, or\nto the previously studied single acceptor+donor state, the grain boundary\nrecombination of a single donor state is suppressed by orders of magnitude. We\nshow numerically that superposition holds near the open-circuit voltage $V_{\\rm\noc}$, so that our dark $J(V)$ relations determine $V_{\\rm oc}$ for a given\nshort circuit current $J_{\\rm sc}$. We finally explicitly show how $V_{\\rm oc}$\ndepends on the grain boundary defect state configurations."
    },
    {
        "anchor": "Probing Spin Accumulation induced Magnetocapacitance in a Single\n  Electron Transistor: The interplay between spin and charge in solids is currently among the most\ndiscussed topics in condensed matter physics. Such interplay gives rise to\nmagneto-electric coupling, which in the case of solids was named\nmagneto-electric effect, as predicted by Curie on the basis of symmetry\nconsiderations. This effect enables the manipulation of magnetization using\nelectrical field or, conversely, the manipulation of electrical polarization by\nmagnetic field. The latter is known as the magnetocapacitance effect. Here, we\nshow that non-equilibrium spin accumulation can induce tunnel\nmagnetocapacitance through the formation of a tiny charge dipole. This dipole\ncan effectively give rise to an additional serial capacitance, which represents\nan extra charging energy that the tunneling electrons would encounter. In the\nsequential tunneling regime, this extra energy can be understood as the energy\nrequired for a single spin to flip. A ferromagnetic single-electron-transistor\nwith tunable magnetic configuration is utilized to demonstrate the proposed\nmechanism. It is found that the extra threshold energy is experienced only by\nelectrons entering the islands, bringing about asymmetry in the measured\nCoulomb diamond. This asymmetry is an unambiguous evidence of spin accumulation\ninduced tunnel magnetocapacitance, and the measured magnetocapacitance value is\nas high as 40%.",
        "positive": "Electrical and Thermal Transport in Metallic Single-Wall Carbon\n  Nanotubes on Insulating Substrates: We analyze transport in metallic single-wall carbon nanotubes (SWNTs) on\ninsulating substrates over the bias range up to electrical breakdown in air. To\naccount for Joule self-heating, a temperature-dependent Landauer model for\nelectrical transport is coupled with the heat conduction equation along the\nnanotube. The electrical breakdown voltage of SWNTs in air is found to scale\nlinearly with their length, approximately as 5 V/um; we use this to deduce a\nthermal conductance between SWNT and substrate g ~ 0.17 +/- 0.03 W/K/m per tube\nlength, which appears limited by the SWNT-substrate interface rather than the\nthermal properties of the substrate itself. We examine the phonon scattering\nmechanisms limiting electron transport, and find the strong temperature\ndependence of the optical phonon absorption rate to have a remarkable influence\non the electrical resistance of micron-length nanotubes. Further analysis\nreveals that unlike in typical metals, electrons are responsible for less than\n15% of the total thermal conductivity of metallic nanotubes around room\ntemperature, and this contribution decreases at high bias or higher\ntemperatures. For interconnect applications of metallic SWNTs, significant\nself-heating may be avoided if power densities are limited below 5 uW/um, or if\nthe SWNT-surrounding thermal interface is optimized."
    },
    {
        "anchor": "Quantum Transport Simulation of III-V TFETs with Reduced-Order K.P\n  Method: III-V tunneling field-effect transistors (TFETs) offer great potentials in\nfuture low-power electronics application due to their steep subthreshold slope\nand large \"on\" current. Their 3D quantum transport study using non-equilibrium\nGreen's function method is computationally very intensive, in particular when\ncombined with multiband approaches such as the eight-band K.P method. To reduce\nthe numerical cost, an efficient reduced-order method is developed in this\narticle and applied to study homojunction InAs and heterojunction GaSb-InAs\nnanowire TFETs. Device performances are obtained for various channel widths,\nchannel lengths, crystal orientations, doping densities, source pocket lengths,\nand strain conditions.",
        "positive": "Taming electronic decoherence in 1D chiral ballistic quantum conductors: Although interesting per se, decoherence and relaxation of single-electron\nexcitations induced by strong effective screened Coulomb interactions in\nQuantum Hall edge channels are an important challenge for the applications of\nelectron quantum optics in quantum information and quantum sensing. In this\npaper, we study intrinsic single-electron decoherence within an ideal\nsingle-electron channel with long-range effective Coulomb interactions to\ndetermine the influence of the material and sample properties. We find that\nweak-coupling materials characterized by a high velocity of hot-electron\nexcitations may offer interesting perspectives for limiting intrinsic\ndecoherence due to electron/electron interactions. We discuss quantitively how\nextrinsic decoherence due to the coupling with the channel's electromagnetic\nenvironment can be efficiently inhibited in specially designed samples at\n$\\nu=2$ with one closed edge channel and we propose a realistic geometry for\ntesting decoherence control in an Hong Ou Mandel experiment."
    },
    {
        "anchor": "Spectrum of pi electrons in bilayer graphene nanoribbons and nanotubes:\n  an analytical approach: We present an analytical description of pi electrons of a finite size bilayer\ngraphene within a framework of the tight-binding model. The bilayered\nstructures considered here are characterized by a rectangular geometry and have\na finite size in one or both directions with armchair- and zigzag-shaped edges.\nWe provide an exact analytical description of the spectrum of pi electrons in\nthe zigzag and armchair bilayer graphene nanoribbons and nanotubes. We analyze\nthe dispersion relations, the density of states, and the conductance\nquantization.",
        "positive": "Optical Signatures of the Tunable Band Gap and Valley-Spin Coupling in\n  Silicene: We investigate the optical response of the silicene and similar materials,\nsuch as germanene, in the presence of an electrically tunable band gap for\nvariable doping. The interplay of spin orbit coupling, due to the buckled\nstructure of these materials, and a perpendicular electric field gives rise to\na rich variety of phases: a topological or quantum spin Hall insulator, a\nvalley-spin-polarized metal and a band insulator. We show that the dynamical\nconductivity should reveal signatures of these different phases which would\nallow for their identification along with the determination of parameters such\nas the spin orbit energy gap. We find an interesting feature where the electric\nfield tuning of the band gap might be used to switch on and off the Drude\nintraband response. Furthermore, in the presence of spin-valley coupling, the\nresponse to circularly polarized light as a function of frequency and electric\nfield tuning of the band gap is examined. Using right- and left-handed circular\npolarization it is possible to select a particular combination of spin and\nvalley index. The frequency for this effect can be varied by tuning the band\ngap."
    },
    {
        "anchor": "Integration of a gate electrode into carbon nanotube devices for\n  scanning tunneling microscopy: We have developed a fabrication process for incorporating a gate electrode\ninto suspended single-walled carbon nanotube structures for scanning tunneling\nspectroscopy studies. The nanotubes are synthesized by chemical vapor\ndeposition directly on a metal surface. The high temperature ~800 C involved in\nthe growth process poses challenging issues such as surface roughness and\nintegrity of the structure which are addressed in this work. We demonstrate the\neffectiveness of the gate on the freestanding part of the nanotubes by\nperforming tunneling spectroscopy that reveals Coulomb blockade diamonds. Our\napproach enables combined scanning tunneling microscopy and gated electron\ntransport investigations of carbon nanotubes.",
        "positive": "Phononic band structure engineering for high-Q gigahertz surface\n  acoustic wave resonators on lithium niobate: Phonons at gigahertz frequencies interact with electrons, photons, and atomic\nsystems in solids, and therefore have extensive applications in signal\nprocessing, sensing, and quantum technologies. Surface acoustic wave (SAW)\nresonators that confine surface phonons can play a crucial role in such\nintegrated phononic systems due to small mode size, low dissipation, and\nefficient electrical transduction. To date, it has been challenging to achieve\nhigh quality (Q) factor and small phonon mode size for SAW resonators at\ngigahertz frequencies. Here, we present a methodology to design compact high-Q\nSAW resonators on lithium niobate operating at gigahertz frequencies. We\nexperimentally verify out designs and demonstrate Q factors in excess of\n$2\\times10^4$ at room temperature ($6\\times10^4$ at 4 Kelvin) and mode area as\nlow as $1.87 \\lambda^2$. This is achieved by phononic band structure\nengineering, which provides high confinement with low mechanical loss. The\nfrequency-Q products (fQ) of our SAW resonators are greater than $10^{13}$.\nThese high-fQ and small mode size SAW resonators could enable applications in\nquantum phononics and integrated hybrid systems with phonons, photons, and\nsolid-state qubits."
    },
    {
        "anchor": "Driven dynamics of a quantum dot electron spin coupled to bath of\n  higher-spin nuclei: The interplay of optical driving and hyperfine interaction between an\nelectron confined in a quantum dot and its surrounding nuclear spin environment\nproduces a range of interesting physics such as mode-locking. In this work, we\ngo beyond the ubiquitous spin 1/2 approximation for nuclear spins and present a\ncomprehensive theoretical framework for an optically driven electron spin in a\nself-assembled quantum dot coupled to a nuclear spin bath of arbitrary spin.\nUsing a dynamical mean-field approach, we compute the nuclear spin polarization\ndistribution with and without the quadrupolar coupling. We find that while\nhyperfine interactions drive dynamic nuclear polarization and mode-locking,\nquadrupolar couplings counteract these effects. The tension between these\nmechanisms is imprinted on the steady-state electron spin evolution, providing\na way to measure the importance of quadrupolar interactions in a quantum dot.\nOur results show that higher-spin effects such as quadrupolar interactions can\nhave a significant impact on the generation of dynamic nuclear polarization and\nhow it influences the electron spin evolution.",
        "positive": "Magnetoconductance signatures of subband structure in semiconductor\n  nanowires: The radial confining potential in a semiconductor nanowire plays a key role\nin determining its quantum transport properties. Previous reports have shown\nthat an axial magnetic field induces flux-periodic conductance oscillations\nwhen the electronic states are confined to a shell. This effect is due to the\ncoupling of orbital angular momentum to the magnetic flux. Here, we perform\ncalculations of the energy level structure, and consequently the conductance,\nfor more general cases ranging from a flat potential to strong surface band\nbending. The transverse states are not confined to a shell, but are distributed\nacross the nanowire. It is found that, in general, the subband energy spectrum\nis aperiodic as a function of both gate voltage and magnetic field. In\nprinciple, this allows for precise identification of the occupied subbands from\nthe magnetoconductance patterns of quasi-ballistic devices. The aperiodicity\nbecomes more apparent as the potential flattens. A quantitative method is\nintroduced for matching features in the conductance data to the subband\nstructure resulting from a particular radial potential, where a functional form\nfor the potential is used that depends on two free parameters. Finally, a\nshort-channel InAs nanowire FET device is measured at low temperature in search\nof conductance features that reveal the subband structure. Features are\nidentified and shown to be consistent with three specific subbands. The\nexperiment is analyzed in the context of the weak localization regime, however,\nwe find that the subband effects predicted for ballistic transport should\nremain visible when back scattering dominates over interband scattering, as is\nexpected for this device."
    },
    {
        "anchor": "Parity protected superconducting diode effect in topological Josephson\n  junctions: In bulk superconductors or Josephson junctions formed in materials with\nspin-orbit interaction, the critical current can depend on the direction of\ncurrent flow and applied magnetic field, an effect known as the superconducting\n(SC) diode effect. Here, we consider the SC diode effect in Josephson junctions\nin nanowire devices. We find that the $4\\pi$-periodic contribution of Majorana\nbound states (MBSs) to the current phase relation (CPR) of single junctions\nresults in a significant enhancement of the SC diode effect when the device\nenters the topological phase. Crucially, this enhancement of the SC diode\neffect is independent of the parity of the junction and therefore protected\nfrom parity altering events, such as quasiparticle poisoning, which have\nhampered efforts to directly observe the $4\\pi$-periodic CPR of MBSs. We show\nthat this effect can be generalized to SQUIDs and that, in such devices, the\nparity-protected SC diode effect can provide a highly controllable probe of the\ntopology in a Josephson junction.",
        "positive": "Effects of Floquet Engineering on the Coherent Exciton Dynamics in\n  Monolayer WS$_2$: Coherent optical manipulation of electronic bandstructures via Floquet\nEngineering is a promising means to control quantum systems on an ultrafast\ntimescale. However, the ultrafast switching on/off of the driving field comes\nwith questions regarding the limits of validity of the Floquet formalism, which\nis defined for an infinite periodic drive, and to what extent the transient\nchanges can be driven adibatically. Experimentally addressing these questions\nhas been difficult, in large part due to the absence of an established\ntechnique to measure coherent dynamics through the duration of the pulse. Here,\nusing multidimensional coherent spectroscopy we explicitly excite, control, and\nprobe a coherent superposition of excitons in the $K$ and $K^\\prime$ valleys in\nmonolayer WS$_2$. With a circularly polarized, red-detuned, pump pulse, the\ndegeneracy of the $K$ and $K^\\prime$ excitons can be lifted and the phase of\nthe coherence rotated. We demonstrate phase rotations during the 100 fs driving\npulse that exceed $\\pi$, and show that this can be described by a combination\nof the AC-Stark shift of excitons in one valley and Bloch-Siegert shift of\nexcitons in the opposite valley. Despite showing a smooth evolution of the\nphase that directly follows the intensity envelope of the pump pulse, the\nprocess is not perfectly adiabatic. By measuring the magnitude of the\nmacroscopic coherence as it evolves before, during, and after the pump pulse we\nshow that there is additional decoherence caused by power broadening in the\npresence of the pump. This non-adiabaticity may be a problem for many\napplications, such as manipulating q-bits in quantum information processing,\nhowever these measurements also suggest ways such effects can be minimised or\neliminated."
    },
    {
        "anchor": "Influence of dephasing process on the quantum Hall effect and the spin\n  Hall effect: We study the influence of the phase relaxation process on Hall resistance and\nspin Hall current of a mesoscopic two-dimensional (2D) four-terminal Hall\ncross-bar with or without Rashba spin-orbit interaction (SOI) in a\nperpendicular uniform magnetic field. We find that the plateaus of the Hall\nresistance with even number of edge states can survive for very strong phase\nrelaxation when the system size becomes much longer than the phase coherence\nlength. On the other hand, the odd integer Hall resistance plateaus arising\nfrom the SOI are easily destroyed by the weak phase relaxation during the\ncompetition between the magnetic field and the SOI which delocalize the edge\nstates. In addition, we have also studied the transverse spin Hall current and\nfound that it exhibits resonant behavior whenever the Fermi level crosses the\nLandau band of the system. The phase relaxation process weakens the resonant\nspin Hall current and enhances the non-resonant spin Hall current.",
        "positive": "Negative Thermal Expansion Coefficient of Graphene Measured by Raman\n  Spectroscopy: The thermal expansion coefficient (TEC) of single-layer graphene is estimated\nwith temperature-dependent Raman spectroscopy in the temperature range between\n200 and 400 K. It is found to be strongly dependent on temperature but remains\nnegative in the whole temperature range, with a room temperature value of\n-8.0x10^{-6} K^{-1}. The strain caused by the TEC mismatch between graphene and\nthe substrate plays a crucial role in determining the physical properties of\ngraphene, and hence its effect must be accounted for in the interpretation of\nexperimental data taken at cryogenic or elevated temperatures."
    },
    {
        "anchor": "Surface States of the Topological Insulator Bi_{1-x}Sb_x: We study the electronic surface states of the semiconducting alloy BiSb.\nUsing a phenomenological tight binding model we show that the Fermi surface of\nthe 111 surface states encloses an odd number of time reversal invariant\nmomenta (TRIM) in the surface Brillouin zone confirming that the alloy is a\nstrong topological insulator. We then develop general arguments which show that\nspatial symmetries lead to additional topological structure, and further\nconstrain the surface band structure. Inversion symmetric crystals have 8 Z_2\n\"parity invariants\", which include the 4 Z_2 invariants due to time reversal.\nThe extra invariants determine the \"surface fermion parity\", which specifies\nwhich surface TRIM are enclosed by an odd number of electron or hole pockets.\nWe provide a simple proof of this result, which provides a direct link between\nthe surface states and the bulk parity eigenvalues. We then make specific\npredictions for the surface state structure for several faces of BiSb. We next\nshow that mirror invariant band structures are characterized by an integer\n\"mirror Chern number\", n_M. The sign of n_M in the topological insulator phase\nof BiSb is related to a previously unexplored Z_2 parameter in the L point k.p\ntheory of pure Bi, which we refer to as the \"mirror chirality\", \\eta. The value\nof \\eta predicted by the tight binding model for Bi disagrees with the value\npredicted by a more fundamental pseudopotential calculation. This explains a\nsubtle disagreement between our tight binding surface state calculation and\nprevious first principles calculations on Bi. This suggests that the tight\nbinding parameters in the Liu Allen model of Bi need to be reconsidered.\nImplications for existing and future ARPES experiments and spin polarized ARPES\nexperiments will be discussed.",
        "positive": "Bolometric detection of mechanical bending waves in suspended carbon\n  nanotubes: We show that it is possible to detect mechanical bending modes on 1 micron\nlong ropes of single walled-carbon nanotubes suspended between 2 metallic\ncontacts. This is done by measuring either their dc resistance in a region of\nstrong temperature dependence (in the vicinity of superconducting or\nmetal-insulator transition), or their critical current. The vibrations are\nexcited by a radio-frequency electric field produced by an antenna located in\nthe vicinity of the sample. We analyze the mechanism of detection of the\nmechanical resonances in terms of heating and phase breaking effects."
    },
    {
        "anchor": "Self-consistent calculations of phonon scattering rates in GaAs\n  transistor structure with one-dimensional electron gas: Self-consistent calculations of acoustic and polar optical phonon scattering\nrates in GaAs quantum wire transistor structures were carried out with account\nof collisional broadening. The influence of the gate bias on the scattering\nrates was examined, too. It was shown that in order to treat the scattering\nrates rigorously it is important to search for electron energy levels by means\nof the self-consistent solution of Schrodinger and Poisson equations and to\ntake into account the collisional broadening.",
        "positive": "Gating of high-mobility two-dimensional electron gases in GaAs/AlGaAs\n  heterostructures: We investigate high-mobility two-dimensional electron gases in AlGaAs\nheterostructures by employing Schottky-gate-dependent measurements of the\nsamples' electron density and mobility. Surprisingly, we find that two\ndifferent sample configurations can be set in situ with mobilities diering by a\nfactor of more than two in a wide range of densities. This observation is\ndiscussed in view of charge redistributions between the doping layers and is\nrelevant for the design of future gateable high-mobility electron gases."
    },
    {
        "anchor": "A magnetic phase-transition graphene transistor with tunable spin\n  polarization: Graphene nanoribbons (GNRs) have been proposed as potential building blocks\nfor field effect transistor (FET) devices due to their quantum confinement\nbandgap. Here, we propose a novel GNR device concept, enabling the control of\nboth charge and spin signals, integrated within the simplest three-terminal\ndevice configuration. In a conventional FET device, a gate electrode is\nemployed to tune the Fermi level of the system in and out of a static bandgap.\nBy contrast, in the switching mechanism proposed here, the applied gate voltage\ncan dynamically open and close an interaction gap, with only a minor shift of\nthe Fermi level. Furthermore, the strong interplay of the band structure and\nedge spin configuration in zigzag ribbons enables such transistors to carry\nspin polarized current without employing an external magnetic field or\nferromagnetic contacts. Using an experimentally validated theoretical model, we\nshow that such transistors can switch at low voltages and high speed, and the\nspin polarization of the current can be tuned from 0% to 50% by using the same\nback gate electrode. Furthermore, such devices are expected to be robust\nagainst edge irregularities and can operate at room temperature. Controlling\nboth charge and spin signal within the simplest FET device configuration could\nopen up new routes in data processing with graphene based devices.",
        "positive": "On the Relation between Interband Scattering and the \"Metallic Phase\" of\n  Two Dimensional Holes in GaAs/AlGaAs: The \"metallic\" regime of holes in GaAs/AlGaAs heterostructures corresponds to\ndensities where two splitted heavy hole bands exist at a zero magnetic field.\nUsing Landau fan diagrams and weak field magnetoresistance curves we extract\nthe carrier density in each band and the interband scattering rates. The\nmeasured inelastic rates depend Arrheniusly on temperature with an activation\nenergy similar to that characterizing the longitudinal resistance. The\n\"metallic\" characteristics, namely, the resistance increase with temperature,\nis hence traced to the activation of inelastic interband scattering. The data\nare used to extract the bands dispersion relations as well as the two\nparticle-hole excitation continua. It is then argued that acoustic plasmon\nmediated Coulomb scattering might be responsible for the Arrhenius dependence\non temperature. The absence of standard Coulomb scattering characterized by a\npower law dependence upon temperature is pointed out."
    },
    {
        "anchor": "Dynamical Coulomb blockade of thermal transport: The role of energy exchange between a quantum system and its environment is\ninvestigated from the perspective of the Onsager conductance matrix. We\nconsider the thermoelectric linear transport of an interacting quantum dot\ncoupled to two terminals under the influence of an electrical potential and a\nthermal bias. We implement in our model the effect of coupling to\nelectromagnetic environmental modes created by nearby electrons within the\nP(E)-theory of dynamical Coulomb blockade. Our findings relate the lack of some\nsymmetries among the Onsager matrix coefficients with an enhancement of the\nefficiency at maximum power and the occurrence of the heat rectification\nphenomenon.",
        "positive": "Critical exponents in metastable decay via quantum activation: We consider decay of metastable states of forced vibrations of a quantum\noscillator close to bifurcation points, where dissipation becomes effectively\nstrong. We show that decay occurs via quantum activation over an effective\nbarrier. The decay probability $W$ scales with the distance $\\eta$ to the\nbifurcation point as $|\\ln W|\\propto \\eta^{\\xi}$. The exponent $\\xi$ is found\nfor a resonantly driven oscillator and an oscillator modulated at nearly twice\nits eigenfrequency."
    },
    {
        "anchor": "Parafermions in a multilegged geometry: Towards a scalable parafermionic\n  network: Parafermionic zero modes are non-Abelian excitations which have been\npredicted to emerge at the boundary of topological phases of matter. Contrary\nto earlier proposals, here we show that such zero modes may also exist in\nmultilegged star junctions of quantum Hall states. We demonstrate that the\nquantum states spanning the degenerate parafermionic Hilbert space may be\ndetected and manipulated through protocols employing quantum antidots and\nfractional edge modes. Such star-shaped setups may be the building blocks of\ntwo-dimensional parafermionic networks.",
        "positive": "Pumping through a quantum dot in the proximity of a superconductor: We study adiabatic pumping through a quantum dot tunnel-coupled to one normal\nand one superconducting lead. We generalize a formula which relates the pumped\ncharge through a quantum dot with Coulomb interaction to the instantaneous\nlocal Green's function of the dot, to systems containing a superconducting\nlead. First, we apply this formula to the case of a non-interacting,\nsingle-level quantum dot in different temperature regimes and for different\nparameter choices, and we compare the results with the case of a system\ncomprising only normal leads. Then we study the infinite-U Anderson model with\na superconducting lead at zero temperature, and we discuss the effect of the\nproximity of the superconductor on the pumped charge."
    },
    {
        "anchor": "Highly tunable nonlinear Hall effects induced by spin-orbit couplings in\n  strained polar transition-metal dichalcogenides: Recently, signatures of nonlinear Hall effects induced by Berry-curvature\ndipoles have been found in atomically thin 1T'/Td-WTe$_2$. In this work, we\nshow that in strained polar transition-metal dichalcogenides(TMDs) with\n2H-structures, Berry-curvature dipoles created by spin degrees of freedom lead\nto strong nonlinear Hall effects. Under an easily accessible uniaxial strain of\norder 0.2%, strong nonlinear Hall signals, characterized by a Berry-curvature\ndipole on the order of 1{\\AA}, arise in electron-doped polar TMDs such as\nMoSSe, and this is easily detectable experimentally. Moreover, the magnitude\nand sign of the nonlinear Hall current can be easily tuned by electric gating\nand strain. These properties can be used to distinguish nonlinear Hall effects\nfrom classical mechanisms such as ratchet effects. Importantly, our system\nprovides a potential scheme for building electrically switchable\nenergy-harvesting rectifiers.",
        "positive": "Optically Detected Magnetic Resonance Imaging: Optically detected magnetic resonance (ODMR) provides ultrasensitive means to\ndetect and image a small number of electron and nuclear spins, down to the\nsingle spin level with nanoscale resolution. Despite the significant recent\nprogress in this field, it has never been combined with the power of pulsed\nmagnetic resonance imaging (MRI) techniques. Here, we demonstrate for the first\ntime how these two methodologies can be integrated using short pulsed magnetic\nfield gradients to spatially-encode the sample. This results in what we denote\nas an \"optically detected magnetic resonance imaging\" (ODMRI) technique. It\noffers the advantage that the image is acquired in parallel from all parts of\nthe sample, with well-defined three-dimensional point-spread function, and\nwithout any loss of spectroscopic information. In addition, this approach may\nbe used in the future for parallel but yet spatially-selective efficient\naddressing and manipulation of the spins in the sample. Such capabilities are\nof fundamental importance in the field of quantum spin-based devices and\nsensors."
    },
    {
        "anchor": "Formation of an order in a system of exciton condensed phase islands in\n  quantum wells: A theory of exciton condensed phase creation in two-dimensional system is\npresented. The theory is applied to explain the appearance of the periodical\nfragmentation which was observed last years in luminescence from the ring\naround laser spot in crystal with double quantum wells.",
        "positive": "Schottky-like barrier characterization of field-effect transistors with\n  multiple quasi-ballistic channels: The potential barrier height at the interface formed by a metal contact and\nmultiple one-dimensional (1D) quasi-ballistic channels in field-effect\ntransistors (FETs) is evaluated across different carbon nanotube and nanowire\ndevice technologies by means of a Landauer-B\\\"uttiker-based extraction\nmethodology (LBM) adapted for multiple 1D-channels. The extraction methodology\nyields values for an effective Schottky barrier height and a gate coupling\ncoefficient, an indicator of the device working at the quantum capacitance\nlimit. The novel LBM-based approach embracing the mechanisms in 1D electronics\nis compared to the conventional activation energy method not considering such\neffects. The latter approach underestimates the potential barrier height at\nmetal-channel interfaces in comparison to the novel methodology. A test\nstructure based on a displaced gate device is proposed based on numerical\ndevice simulation results towards an improved accuracy of the method."
    },
    {
        "anchor": "A back-to-back diode model applied to MoS2 van der Waals Schottky diodes: The use of metal van der Waals contacts and the implicit reduction in\nFermi-level pinning in contacted semiconductors has led to remarkable device\noptimizations. For example, using graphene as an electrical contact allows for\ntunable Schottky barriers in transistors and barristors. In this study, we\npresent a double Schottky barrier model and apply it to barrier tunable all van\nder Waals transistors. In a molybdenum disulfide (MoS$_2$) transistor with\ngraphene and few-layer graphene contacts, we find that the model can be applied\nto extract Schottky barrier heights that agree with the Schottky-Mott rule from\nsimple two-terminal current-voltage measurements at room temperature.\nFurthermore, we show tunability of the Schottky barrier \\textit{in-situ} using\na regional contact gate. Our results show that a basic back-to-back diode\nmodel, applied to two terminal measurements, can capture the diode properties\nof all-van-der-Waals transistors relatively well.",
        "positive": "Instabilities of layers of deposited molecules on chemically stripe\n  patterned substrates: Ridges vs. drops: A mesoscopic continuum model is employed to analyse the transport mechanisms\nand structure formation during the redistribution stage of deposition\nexperiments where organic molecules are deposited on a solid substrate with\nperiodic stripe-like wettability patterns. Transversally invariant ridges\nlocated on the more wettable stripes are identified as very important transient\nstates and their linear stability is analysed. It is found that there exist two\ndifferent instability modes that result (i) at large ridge volume in the\nformation of bulges that spill from the more wettable stripes onto the less\nwettable bare substrate and (ii) at small ridge volume in the formation of\nsmall droplets located on the more wettable stripes. These predictions are\nconfirmed by direct numerical simulations of the fully nonlinear evolution\nequation for two-dimensional substrates. In addition, the influence of\ndifferent transport mechanisms during redistribution is investigated focusing\non the cases of convective transport with no-slip at the substrate, transport\nvia diffusion in the film bulk and via diffusion at the film surface. In\nparticular, it is shown that the transport process does neither influence the\nlinear stability thresholds nor the sequence of morphologies observed in the\ntime simulation, but only the ratio of the time scales of the different process\nphases."
    },
    {
        "anchor": "Dynamic screening and plasmon spectrum in bilayer graphene: We have theoretically studied the collective response properties of the\ntwo-dimensional chiral electron gas in bilayer graphene within the random phase\napproximation. The cooperation of external controlling factors like\nperpendicular electric bias, temperature, doping, and substrate background\nprovides great freedom to manipulate the dynamic dielectric function and the\nlow-energy plasmon dispersion of the system. Intriguing situations with\npotential application are systematically explored and discussed. Extra undamped\nplasmon modes might emerge under electric bias. They have almost zero group\nvelocities and are easy to manipulate.",
        "positive": "Electron Waiting Times in Non-Markovian Quantum Transport: We formulate a quantum theory of electron waiting time distributions for\ncharge transport in nano-structures described by non-Markovian generalized\nmaster equations. We illustrate our method by calculating the waiting time\ndistribution of electron transport through a dissipative double quantum dot,\nwhere memory effects are present due to a strongly coupled heat bath. We\nconsider the influence of non-Markovian dephasing on the distribution of\nelectron waiting times and discuss how spectral properties of the heat bath may\nbe detected through measurements of the electron waiting time."
    },
    {
        "anchor": "A quantum dot close to Stoner instability: the role of Berry's Phase: The physics of a quantum dot with electron-electron interactions is well\ncaptured by the so called \"Universal Hamiltonian\" if the dimensionless\nconductance of the dot is much higher than unity. Within this scheme\ninteractions are represented by three spatially independent terms which\ndescribe the charging energy, the spin-exchange and the interaction in the\nCooper channel. In this paper we concentrate on the exchange interaction and\ngeneralize the functional bosonization formalism developed earlier for the\ncharging energy. This turned out to be challenging as the effective bosonic\naction is formulated in terms of a vector field and is non-abelian due to the\nnon-commutativity of the spin operators. Here we develop a geometric approach\nwhich is particularly useful in the mesoscopic Stoner regime, i.e., when the\nstrong exchange interaction renders the system close the the Stoner\ninstability. We show that it is sufficient to sum over the adiabatic paths of\nthe bosonic vector field and, for these paths, the crucial role is played by\nthe Berry phase. Using these results we were able to calculate the magnetic\nsusceptibility of the dot. The latter, in close vicinity of the Stoner\ninstability point, matches very well with the exact solution [I.S. Burmistrov,\nY. Gefen, M.N. Kiselev, JETP Lett. 92 (2010) 179].",
        "positive": "Properties of the Majorana-state tunneling Josephson junction mediated\n  by an interacting quantum dot: We consider a model of a Josephson junction of two topological\nsuperconducting wires mediated by an interacting quantum dot. An additional\nnormal electrode coupled to the dot from the top allows to probe its density of\nstates. The Majorana states adjacent to the dot hybridize across the junction\nand from a bound state in the dot. The dot is subjected to the effective\nmagnetic field arising from the superposition of the fields driving each wire\ninto topological states, which, dependent on the angle between the fields,\nintroduces variable Zeeman splitting of the dot active level. We show that\nelectron interactions in the dot diminish the characteristic for Majoranas zero\nbias peak arising in the transverse conductance through the dot and introduce\nan overall asymmetry of the conductance. They also renormalize the\nhybridization between the end-state Majoranas in shorter wires. The Majorana\nspin polarization is determined by the effective magnetic field in the dot.\nPhase-biased Josephson current exhibits spin polarization in thermal\nequilibrium, which possesses characteristic $4\\pi$ periodicity, and its sign\ncan be switched when an unpaired Majorana state is present in the junction. We\nalso observe spin-dependent Majorana state \"leaking\", which can be controlled\nby the position of the dot level in energy scale."
    },
    {
        "anchor": "Dynamics and Current Fluctuations in AC driven Charge Shuttle: The behavior of a charge shuttle under a pure AC field has been recently\nconsidered theoretically and experimentally. If the system presents an\nasymmetry in the tunneling amplitudes the device acts as a\nnano-electromechanical rectifier, transforming a pure AC voltage field into a\ndirect curren. In this paper we first review the model and the appearance of\nthe rectifying effect for bias voltages below the threshold of\nself-oscillation. We discuss in some details the dynamics of the central island\nthat, like the current, presents strong dependence on the forcing AC field\nfrequency. In presence of both a constant and a small oscillating bias voltage\nwe analyze the transition from the static to self-oscillating solution. We then\nconsider current fluctuations (full counting statistics) for periodic motion of\nthe grain. We explicitly evaluate the current noise numerically and we find\nthat it shows clear signatures of correlated transport at certain locking\nfrequencies. In the adiabatic limit we obtain a simple expression for the\nfull-counting statistics and calculate explicitly the first four moments.",
        "positive": "Effect of demagnetization factor dependence on energy of ultra-thin\n  ferromagnetic films with four layers: Simple cubic and body centered cubic ferromagnetic lattices with four layers\nwere studied using Heisenberg Hamiltonian. According to 3-D plots, the films\nwith four layers can be easily oriented in certain directions under the\ninfluence of particular demagnetization factor and angles for both sc(001) and\nbcc(001) ferromagnetic lattice structures. A flat part can be seen in the\nmiddle of 3-D plots in addition to periodic variations. When the\ndemagnetization factor is given by =6, sc(001) film with four layers can be\neasily oriented in 0.6 radians direction for the energy parameter values used\nin this simulation. Under the influence of demagnetization factor given by =5.2\n, thin film of bcc(001) lattice with four layers can be easily oriented along\n0.63 radians direction."
    },
    {
        "anchor": "Spin Texture in a Cold Exciton Gas: We report on the observation of a spin texture in a cold exciton gas in a\nGaAs/AlGaAs coupled quantum well structure. The spin texture is observed around\nthe exciton rings. The observed phenomena include: a ring of linear\npolarization, a vortex of linear polarization with polarization perpendicular\nto the radial direction, an anisotropy in the exciton flux, a skew of the\nexciton fluxes in orthogonal circular polarizations and a corresponding\nfour-leaf pattern of circular polarization, a periodic spin texture, and\nextended exciton coherence in the region of the polarization vortex. The data\nindicate a transport regime where the spin polarization is locked to the\ndirection of particle propagation and scattering is suppressed.",
        "positive": "Transport through Quantum Anomalous Hall Bilayers with Lattice Mismatch: We theoretically investigate quantum transport properties of quantum\nanomalous Hall bilayers, with arbitrary ratio of lattice constants, i.e., with\nlattice mismatch. In the simplest case of ratio 1 (but with different model\nparameters in two layers), the inter-layer coupling results in resonant\ntraversing between forward propagating waves in two layers. In the case of\ngeneric ratios, there is a quantized conductance plateau originated from two\nChern numbers associated with two layers. However, the phase boundary of this\nquantization plateau consists of a fractal transitional region (instead of a\nclear transition line) of interpenetrating edge states (with quantized\nconductance) and bulk states (with unquantized conductance). We attribute these\nbulk states as mismatch induced in-gap bulk states. Different from in-gap\nlocalized states induced by random disorder, these in-gap bulk states are\nextended in the limit of vanishing random disorder. However, the detailed fine\nstructure of this transitional region is sensitive to disorder, lattice\nstructure, sample size, and even the configuration of leads connecting to it,\ndue to the bulk and topologically trivial nature of these in-gap bulk states."
    },
    {
        "anchor": "Azimuthal Spin Wave Excitations in Magnetic Nanodots over the Soliton\n  Background: Vortex, Bloch and N\u00e9el-like skyrmions: We study azimuthal spin-wave (SW) excitations in a circular ferromagnetic\nnanodot in different inhomogeneous, topologically non-trivial magnetization\nstates, specifically, vortex, Bloch-type skyrmion and N\\'eel-type skyrmion\nstates. Continuous mapping of the SW spectrum between these states is realized\nwith gradual change of the out-of-plane magnetic anisotropy and\nDzyaloshinskii-Moriya exchange interaction (DMI). Our study shows lifting of\nthe SW frequencies degeneracy and change in systematics of the frequency\nlevels. The change is induced by a geometrical Berry phase, that is present for\nthe dot-edge localized SWs in a vortex state and vanishes in skyrmion states.\nFurthermore, channeling of the azimuthal SWs localized at the skyrmion edge is\npresent and induces large frequency splitting. This is attributed to DMI\ninduced nonreciprocity, while coupling of the breathing and gyrotropic modes is\nrelated to soliton motion. Finally, an efficient coupling of the dynamic\nmagnetization in the skyrmion state to uniform magnetic field in nanodots with\nnon-circular symmetry is shown.",
        "positive": "High-frequency gate manipulation of a bilayer graphene quantum dot: We report transport data obtained for a double-gated bilayer graphene quantum\ndot. In Coulomb blockade measurements, the gate dielectric Cytop(TM) is found\nto provide remarkable electronic stability even at cryogenic temperatures.\nMoreover, we demonstrate gate manipulation with square shaped voltage pulses at\nfrequencies up to 100 MHz and show that the signal amplitude is not affected by\nthe presence of the capacitively coupled back gate."
    },
    {
        "anchor": "Effect of anisotropic spin absorption on the Hanle effect in lateral\n  spin valves: We have succeeded in fully describing dynamic properties of spin current\nincluding the different spin absorption mechanism for longitudinal and\ntransverse spins in lateral spin valves, which enables to elucidate intrinsic\nspin transport and relaxation mechanism in the nonmagnet. The deduced spin\nlifetimes are found independent of the contact type. From the transit-time\ndistribution of spin current extracted from the Fourier transform in Hanle\nmeasurement data, the velocity of the spin current in Ag with Py/Ag Ohmic\ncontact turns out much faster than that expected from the widely used model.",
        "positive": "Magnon spin Nernst effect in antiferromagnets: We predict that a temperature gradient can induce a magnon-mediated spin Hall\nresponse in an antiferromagnet with non-trivial magnon Berry curvature. We\ndevelop a linear response theory which gives a general condition for a Hall\ncurrent to be well defined, even when the thermal Hall response is forbidden by\nsymmetry. We apply our theory to a honeycomb lattice antiferromagnet and\ndiscuss a role of magnon edge states in a finite geometry."
    },
    {
        "anchor": "Coherent manipulation of Andreev states in superconducting atomic\n  contacts: Coherent control of quantum states has been demonstrated in a variety of\nsuperconducting devices. In all these devices, the variables that are\nmanipulated are collective electromagnetic degrees of freedom: charge,\nsuperconducting phase, or flux. Here, we demonstrate the coherent manipulation\nof a quantum system based on Andreev bound states, which are microscopic\nquasiparticle states inherent to superconducting weak links. Using a circuit\nquantum electrodynamics setup we perform single-shot readout of this \"Andreev\nqubit\". We determine its excited state lifetime and coherence time to be in the\nmicrosecond range. Quantum jumps and parity switchings are observed in\ncontinuous measurements. In addition to possible quantum information\napplications, such Andreev qubits are a testbed for the physics of single\nelementary excitations in superconductors.",
        "positive": "Correlated Cooper pair transport and microwave photon emission in the\n  dynamical Coulomb blockade: We study theoretically electromagnetic radiation emitted by inelastic\nCooper-pair tunneling. We consider a dc-voltage-biased superconducting\ntransmission line terminated by a Josephson junction. We show that the\ngenerated continuous-mode electromagnetic field can be expressed as a function\nof the time-dependent current across the Josephson junction. The leading-order\nexpansion in the tunneling coupling, similar to the \"$P(E)$-theory\", has\npreviously been used to investigate the photon emission statistics in the limit\nof sequential (independent) Cooper-pair tunneling. By explicitly evaluating the\nsystem characteristics up to the fourth-order in the tunneling coupling, we\naccount for dynamics between consecutively tunneling Cooper pairs. Within this\napproach we investigate how temporal correlations in the charge transport can\nbe seen in the first- and second-order coherences of the emitted microwave\nradiation."
    },
    {
        "anchor": "Wannier Center Sheets in Topological Insulators: We argue that various kinds of topological insulators (TIs) can be\ninsightfully characterized by an inspection of the charge centers of the hybrid\nWannier functions, defined as the orbitals obtained by carrying out a Wannier\ntransform on the Bloch functions in one dimension while leaving them Bloch-like\nin the other two. From this procedure, one can obtain the Wannier charge\ncenters (WCCs) and plot them in the two-dimensional projected Brillouin zone.\nWe show that these WCC sheets contain the same kind of topological information\nas is carried in the surface energy bands, with the crucial advantage that the\ntopological properties of the bulk can be deduced from bulk calculations alone.\nThe distinct topological behaviors of these WCC sheets in trivial, Chern, weak,\nstrong, and crystalline TIs are first illustrated by calculating them for\nsimple tight-binding models. We then present the results of first-principles\ncalculations of the WCC sheets in the trivial insulator Sb$_2$Se$_3$, the weak\nTI KHgSb, and the strong TI Bi$_2$Se$_3$, confirming the ability of this\napproach to distinguish between different topological behaviors in an\nadvantageous way.",
        "positive": "Quantum Computing with Majorana Fermion Codes: We establish a unified framework for Majorana-based fault-tolerant quantum\ncomputation with Majorana surface codes and Majorana color codes. All logical\nClifford gates are implemented with zero time overhead. This is done by\nintroducing a protocol for Pauli product measurements with tetrons and hexons\nwhich only requires local 4-Majorana parity measurements. An analogous protocol\nis used in the fault-tolerant setting, where tetrons and hexons are replaced by\nMajorana surface code patches, and parity measurements are replaced by lattice\nsurgery, still only requiring local few-Majorana parity measurements. To this\nend, we discuss twist defects in Majorana fermion surface codes and adapt the\ntechnique of twist-based lattice surgery to fermionic codes. Moreover, we\npropose a new family of codes that we refer to as Majorana color codes, which\nare obtained by concatenating Majorana surface codes with small Majorana\nfermion codes. Majorana surface and color codes can be used to decrease the\nspace overhead and stabilizer weight compared to their bosonic counterparts."
    },
    {
        "anchor": "Tunable Angle Dependent Magnetization Dynamics in Ni80Fe20 Nano-cross\n  Structures of Varying Size: We demonstrate a large angular dependence of magnetization dynamics in\nNi80Fe20 nano-cross arrays of varying sizes. By subtle variation of the\nazimuthal angle of an in-plane bias magnetic field, the spin configuration and\nthe ensuing spin-wave dynamics, including mode softening, mode splitting, mode\ncrossover and mode merging, can be drastically varied to the extent that a\nfrequency minimum corresponding to mode softening converts to a mode crossover,\nvarious mode splitting and mode crossover disappear and additional mode\nsplitting appears. Numerically simulated spin-wave spectra and phase profiles\nrevealed the nature of various spin-wave modes and the origin of above\nvariation of the dynamics with bias-field angle. All of these above\nobservations are further modified with the variation of dimensions of the\nnano-cross. The numerically calculated magnetostatic field distributions\nfurther supports the variation of dynamics with bias-field angle. These results\nopen a new avenue for engineering the nano-cross based magnetic devices such as\nmagnetic storage, spin-wave logic and on-chip data communication devices.",
        "positive": "High Performance Single Layered WSe2 p-FETs with Chemically Doped\n  Contacts: We report high performance p-type field-effect transistors based on single\nlayered (thickness, ~0.7 nm) WSe2 as the active channel with chemically doped\nsource/drain contacts and high-{\\kappa} gate dielectrics. The top-gated\nmonolayer transistors exhibit a high effective hole mobility of ~250 cm2/Vs,\nperfect subthreshold swing of ~60 mV/dec, and ION/IOFF of >10^6 at room\ntemperature. Special attention is given to lowering the contact resistance for\nhole injection by using high work function Pd contacts along with degenerate\nsurface doping of the contacts by patterned NO2 chemisorption on WSe2. The\nresults here present a promising material system and device architecture for\np-type monolayer transistors with excellent characteristics."
    },
    {
        "anchor": "Spin Wave Driven Skyrmions in a Bipartite Antiferromagnetic Lattice: We show that a Skyrmion in a classical bipartite antiferromagnetic lattice\ncan be spatially displaced in a controlled manner by externally applied spin\nwaves. We reveal the relation between the Skyrmion motion and the spin wave\nproperties. To this end, we derive a classical spin wave formalism which is\ntailored to the antiferromagnetic two-dimensional square lattice. The\nantiferromagnetic spin waves can be classified into two types with respect to\ntheir polarization, with two modes each. The circularly polarized spin waves\noscillate with different amplitudes in the respective sublattices and induce a\nSkyrmion Hall effect. The two modes are symmetric under sublattices exchange\nand determine the overall sign of the Hall angle. Linearly polarized spin waves\noscillate elliptically, however, with the same amplitude on each sublattice.\nThese accelerate the Skyrmion solely into their own propagation direction. The\ntwo modes are symmetric under component x-y exchange and impact Bloch- or\nN\\'eel Skyrmions differently. Our results indicate possible technical\napplications of spin-wave driven Skyrmion motion. As one example we propose a\nracetrack where spin waves pump Skyrmions along the track in antiferromagnets.",
        "positive": "Transverse field-induced effects in carbon nanotubes: We investigate the properties of conduction electrons in single-walled\narmchair carbon nanotubes (SWNT) in the presence of both transverse electric\nand magnetic fields. We find that these fields provide a controlled means of\ntuning low-energy band structure properties such as inducing gaps in the\nspectrum, breaking various symmetries and altering the Fermi velocities. We\nshow that the fields can strongly affect electron-electron interaction,\nyielding tunable Luttinger liquid physics, the possibility of spin-charge-band\nseparation, and a competition between spin-density-wave and charge-density-wave\norder. For short tubes, the fields can alter boundary conditions and associated\nsingle-particle level spacings as well as quantum dot behavior."
    },
    {
        "anchor": "Transmission in Graphene through Time-oscillating Linear Barrier: Transmission probabilities of Dirac fermions in graphene under linear barrier\npotential oscillating in time are investigated. Solving Dirac equation we end\nup with the solutions of the energy spectrum depending on several modes coming\nfrom the oscillations. These will be used to obtain a transfer matrix that\nallows to determine transmission amplitudes of all modes. Due to numerical\ndifficulties in truncating the resulting coupled channel equations, we limit\nourselves to low quantum channels, i.e. $l = 0, \\pm1$, and study the three\ncorresponding transmission probabilities.",
        "positive": "Low-threshold exciton transport and control in atomically thin\n  semiconductors: Understanding and controlling the nanoscale transport of excitonic\nquasiparticles in atomically thin 2D semiconductors is crucial to produce\nhighly efficient nano-excitonic devices. Here, we present a nano-gap device to\nselectively confine excitons or trions of 2D transition metal dichalcogenides\nat the nanoscale, facilitated by the drift-dominant exciton funnelling into the\nstrain-induced local spot. We investigate the spatio-spectral characteristics\nof the funnelled excitons in a WSe2 monolayer (ML) and converted trions in a\nMoS2 ML using hyperspectral tip-enhanced photoluminescence (TEPL) imaging with\n<15 nm spatial resolution. In addition, we dynamically control the exciton\nfunnelling and trion conversion rate by the GPa scale tip pressure engineering.\nThrough a drift-diffusion model, we confirm an exciton funnelling efficiency of\n~25 % with a significantly low strain threshold (~0.1 %) which sufficiently\nexceeds the efficiency of ~3 % in previous studies. This work provides a new\nstrategy to facilitate efficient exciton transport and trion conversion of 2D\nsemiconductor devices."
    },
    {
        "anchor": "Magnetotransport in low-density $p$-Si/SiGe heterostructures: From metal\n  through hopping insulator to Wigner glass: We study DC and AC transport in low-density $p-$Si/SiGe heterostructures at\nlow temperatures and in a broad domain of magnetic fields up to 18 T. Complex\nAC conductance is determined from simultaneous measurement of velocity and\nattenuation of a surface acoustic wave propagating in close vicinity of the 2D\nhole layer. The observed behaviors of DC and AC conductance are interpreted as\nan evolution from metallic conductance at B=0 through hopping between localized\nstates in intermediate magnetic fields (close to the plateau of the integer\nquantum Hall effect corresponding to the Landau-level filling factor $\\nu$=1)\nto formation of the Wigner glass in the extreme quantum limit ($B\\gtrsim 14$,\n$T \\lesssim 0.8$ K).",
        "positive": "Kinetic theory of shot noise in non-degenerate diffusive conductors: We investigate current fluctuations in non-degenerate semiconductors, on\nlength scales intermediate between the elastic and inelastic mean free paths.\nWe present an exact solution of the non-linear kinetic equations in the regime\nof space-charge limited conduction, without resorting to the drift\napproximation of previous work. By including the effects of a finite voltage\nand carrier density in the contact region, a quantitative agreement is obtained\nwith Monte Carlo simulations by Gonz{\\'a}lez et al., for a model of an\nenergy-independent elastic scattering rate. The shot-noise power $P$ is\nsuppressed below the Poisson value $P_{Poisson}=2e\\bar I$ (at mean current\n$\\bar I$) by the Coulomb repulsion of the carriers. The exact suppression\nfactor is close to 1/3 in a three-dimensional system, in agreement with the\nsimulations and with the drift approximation. Including an energy dependence of\nthe scattering rate has a small effect on the suppression factor for the case\nof short-range scattering by uncharged impurities or quasi-elastic scattering\nby acoustic phonons. Long-range scattering by charged impurities remains an\nopen problem."
    },
    {
        "anchor": "Tuning exciton recombination rates in doped transition\n  metaldichalcogenides: Monolayer transition metal dichalcogenides (TMDs) are direct gap\nsemiconductors that hold great promise for advanced applications in photonics\nand optoelectronics. Understanding the interplay between their radiative and\nnon-radiative recombination pathways is thus of crucial importance not only for\nfundamental studies but also for the design of future nanoscale on-chip\ndevices. Here, we investigate the interplay between doping and exciton-exciton\nannihilation (EEA) and their impact on the photoluminescence quantum yield in\ndifferent TMD samples and related heterostructures. We demonstrate that the EEA\nthreshold increases in highly doped samples, where the radiative and\nnon-radiative recombination of trions dominates.",
        "positive": "A quantum dot coupled to a suspended-beam mechanical resonator: from the\n  unresolved- to the resolved-sideband regime: We present experiments in which self-assembled InAs quantum dots are coupled\nto a thin, suspended-beam GaAs resonator. The quantum dots are driven\nresonantly and the resonance fluorescence is detected. The narrow quantum-dot\nlinewidths, just a factor of three larger than the transform limit, result in a\nhigh sensitivity to the mechanical motion. We show that one quantum dot couples\nto eight mechanical modes spanning a frequency range from $30$ to\n$600~\\mathrm{MHz}$: one quantum dot provides an extensive characterisation of\nthe mechanical resonator. The coupling spans the unresolved-sideband to the\nresolved-sideband regimes. Finally, we present the first detection of\nthermally-driven phonon sidebands (at $4.2~\\mathrm{K}$) in the\nresonance-fluoresence spectrum."
    },
    {
        "anchor": "Thermal Effects on Photon-Induced Quantum Transport: We theoretically investigate laser induced quantum transport in a two-level\nquantum dot attached to electric contacts. Our approach, based on\nnonequilibrium Green function technique, allows to include thermal effects on\nthe photon-induced quantum transport and excitonic coherent dynamics. By\nsolving a set of coupled integrodifferential equations, involving correlation\nand propagator functions, we obtain the photocurrent and the dot occupations as\na function of time. The characteristic coherent Rabi oscillations are found in\nboth occupations and photocurrent, with two distinct sources of decoherence:\nincoherent tunneling and thermal fluctuations. In particular, for increasing\ntemperature the dot becomes more thermally occupied which shrinks the amplitude\nof the Rabi oscillations, due to Pauli blockade. Finally, due to the interplay\nbetween photon and thermal induced electron populations, the photocurrent can\nswitch sign as time evolves and its stationary value can be maximized by\ntunning the laser intensity.",
        "positive": "Near-field Electrical Detection of Optical Plasmons and Single Plasmon\n  Sources: Photonic circuits can be much faster than their electronic counterparts, but\nthey are difficult to miniaturize below the optical wavelength scale. Nanoscale\nphotonic circuits based on surface plasmon polaritons (SPs) are a promising\nsolution to this problem because they can localize light below the diffraction\nlimit. However, there is a general tradeoff between the localization of an SP\nand the efficiency with which it can be detected with conventional far-field\noptics. Here we describe a new all-electrical SP detection technique based on\nthe near-field coupling between guided plasmons and a nanowire field-effect\ntransistor. We use the technique to electrically detect the plasmon emission\nfrom an individual colloidal quantum dot coupled to an SP waveguide. Our\ndetectors are both nanoscale and highly efficient (0.1 electrons/plasmon), and\na plasmonic gating effect can be used to amplify the signal even higher (up to\n50 electrons/plasmon). These results enable new on-chip optical sensing\napplications and are a key step towards \"dark\" optoplasmonic nanocircuits in\nwhich SPs can be generated, manipulated, and detected without involving\nfar-field radiation."
    },
    {
        "anchor": "Phase-coherence time saturation in mesoscopic systems: wave function\n  collapse: A finite phase-coherence time $\\tau_{\\phi}^{meas}$ emerges from iterative\nmeasurement onto a quantum system. For a rapid sequence, the phase-coherence\ntime is found explicitly. For the stationary charge conduction problem, it is\nbounded. At all order, in the time-interval of measurements, we propose a\ngeneral expression for $\\tau_{\\phi}^{meas}$.",
        "positive": "Mesoscopic fluctuations of the ground state spin of a small metal\n  particle: We study the statistical distribution of the ground state spin for an\nensemble of small metallic grains, using a random-matrix toy model. Using the\nHartree Fock approximation, we find that already for interaction strengths well\nbelow the Stoner criterion there is an appreciable probability that the ground\nstate has a finite, nonzero spin. Possible relations to experiments are\ndiscussed."
    },
    {
        "anchor": "Orbit topology analysed from $\u03c0$ phase shift of magnetic quantum\n  oscillations in three-dimensional Dirac semimetal: With the emergence of Dirac fermion physics in the field of condensed matter,\nmagnetic quantum oscillations (MQOs) have been used to discern the topology of\norbits in Dirac materials. However, many previous researchers have relied on\nthe single-orbit Lifshiftz-Kosevich formula, which overlooks the significant\neffect of degenerate orbits on MQOs. Since the single-orbit LK formula is valid\nfor massless Dirac semimetals with small cyclotron masses, it is imperative to\ngeneralize the method applicable to a wide range of Dirac semimetals, whether\nmassless or massive. This report demonstrates how spin-degenerate orbits affect\nthe phases in MQOs of three-dimensional massive Dirac semimetal, NbSb$_2$. With\nvarying the direction of the magnetic field, an abrupt $\\pi$ phase shift is\nobserved due to the interference between the spin-degenerate orbits. We\ninvestigate the effect of cyclotron mass on the $\\pi$ phase shift and verify\nits close relation to the phase from the Zeeman coupling. We find that the\n$\\pi$ phase shift occurs when the cyclotron mass is 1/2 of the electron mass,\nindicating the effective spin gyromagnetic ratio is $g_s$ = 2. Our approach is\nnot only useful for analysing MQOs of massless Dirac semimetals with a small\ncyclotron mass, but also can be used for MQOs in massive Dirac materials with\ndegenerate orbits, especially in topological materials with a sufficiently\nlarge cyclotron mass. Furthermore, this method provides a useful way to\nestimate the precise $g_s$ value of the material.",
        "positive": "Effect of a tunnel barrier on the scattering from a Majorana bound state\n  in an Andreev billiard: We calculate the joint distribution $P(S,Q)$ of the scattering matrix $S$ and\ntime-delay matrix $Q=-i\\hbar S^\\dagger dS/dE$ of a chaotic quantum dot coupled\nby point contacts to metal electrodes. While $S$ and $Q$ are statistically\nindependent for ballistic coupling, they become correlated for tunnel coupling.\nWe relate the ensemble averages of $Q$ and $S$ and thereby obtain the average\ndensity of states at the Fermi level. We apply this to a calculation of the\neffect of a tunnel barrier on the Majorana resonance in a topological\nsuperconductor. We find that the presence of a Majorana bound state is hidden\nin the density of states and in the thermal conductance if even a single\nscattering channel has unit tunnel probability. The electrical conductance\nremains sensitive to the appearance of a Majorana bound state, and we calculate\nthe variation of the average conductance through a topological phase\ntransition."
    },
    {
        "anchor": "Magnetic Domain Walls as Hosts of Spin Superfluids and Generators of\n  Skyrmions: A domain wall in a magnet with easy-axis anisotropy is shown to harbor spin\nsuperfluid associated with its spontaneous breaking of the U(1) spin-rotational\nsymmetry. The spin superfluid is shown to have several topological properties,\nwhich are absent in conventional superfluids. First, the associated phase slips\ncreate and destroy skyrmions to obey the conservation of the total skyrmion\ncharge, which allows us to use a domain wall as a generator and detector of\nskyrmions. Secondly, the domain wall engenders the emergent magnetic flux for\nmagnons along its length, which are proportional to the spin supercurrent\nflowing through it, and thereby provides a way to manipulate magnons. Thirdly,\nthe spin supercurrent can be driven by the magnon current traveling across it\nowing to the spin transfer between the domain wall and magnons, leading to the\nmagnonic manipulation of the spin superfluid. The theory for superfluid spin\ntransport within the domain wall is confirmed by numerical simulations.",
        "positive": "Charge Relaxation in the Presence of Shot Noise in Coulomb Coupled\n  Mesoscopic Systems: In the presence of shot noise the charge on a mesoscopic conductor\nfluctuates. We are interested in the charge fluctuations which arise if the\nconductor is in the proximity of a gate to which it is coupled by long range\nCoulomb forces only. Specifically we consider a gate coupled to the edge of a\nHall bar subject to a quantizing magnetic field which contains a quantum point\ncontact. The gate is located away from the quantum point contact. We evaluate\nthe charge relaxation resistance for this geometry. The charge relaxation\nresistance determines the current fluctuations and potential fluctuations\ninduced into the gate. If there is only one edge channel the charge relaxation\nresistance is determined by transmission and reflection probabilities alone,\nbut in the presence of many channels the density of states of all edge states\ndetermines this resistance."
    },
    {
        "anchor": "Extensive degeneracy, Coulomb phase and magnetic monopoles in an\n  artificial realization of the square ice model: Artificial spin ice systems have been introduced as a possible mean to\ninvestigate frustration effects in a well-controlled manner by fabricating\nlithographically-patterned two-dimensional arrangements of interacting magnetic\nnanostructures. This approach offers the opportunity to visualize\nunconventional states of matter, directly in real space, and triggered a wealth\nof studies at the frontier between nanomagnetism, statistical thermodynamics\nand condensed matter physics. Despite the strong efforts made these last ten\nyears to provide an artificial realization of the celebrated square ice model,\nno simple geometry based on arrays of nanomagnets succeeded to capture the\nmacroscopically degenerate ground state manifold of the corresponding model.\nInstead, in all works reported so far, square lattices of nanomagnets are\ncharacterized by a magnetically ordered ground state consisting of local\nflux-closure configurations with alternating chirality. Here, we show\nexperimentally and theoretically, that all the characteristics of the square\nice model can be observed if the artificial square lattice is properly\ndesigned. The spin configurations we image after demagnetizing our arrays\nreveal unambiguous signatures of an algebraic spin liquid state characterized\nby the presence of pinch points in the associated magnetic structure factor.\nLocal excitations, i.e. classical analogues of magnetic monopoles, are found to\nbe free to evolve in a massively degenerated, divergence-free vacuum. We thus\nprovide the first lab-on-chip platform allowing the investigation of collective\nphenomena, including Coulomb phases and ice-like physics.",
        "positive": "Vibrational Tamm states at the edges of graphene nanoribbons: We study vibrational states localized at the edges of graphene nanoribbons.\nSuch surface oscillations can be considered as a phonon analog of Tamm states\nwell known in the electronic theory. We consider both armchair and zigzag\ngraphene stripes and demonstrate that surface modes correspond to phonons\nlocalized at the edges of the graphene nanoribbon, and they can be classified\nas in-plane and out-of-plane modes. In addition, in armchair nanoribbons\nanharmonic edge modes can experience longitudinal localization in the form of\nself-localized nonlinear modes, or surface breather solitons."
    },
    {
        "anchor": "Field-induced Berry connection and planar Hall effect in tilted Weyl\n  semimetals: We propose the linear and nonlinear planar Hall effect (PHE) in tilted Weyl\nsemimetals in the presence of an in-plane magnetic and electric field, where\nthe field-induced Berry connection (FBC) plays a key role. We show that the PHE\nis ascribed to the quantum metric, distinct from the well-known chiral\nanomaly-induced PHE arising from the Berry curvature. Using a tilting vector to\ndescribe the model, we demonstrate the constrains on the linear and nonlinear\nPHE by the tilting directions. The linear PHE is intrinsic that is determined\nby the topological properties of energy bands, whereas the nonlinear PHE is\nextrinsic. The predicted linear and nonlinear PHE are inherently different from\nothers and may shed light on a deeper understanding on transport nature of the\ntilted Weyl semimetals.",
        "positive": "Unconventional Thermal Magnon Hall Effect in a Ferromagnetic Topological\n  Insulator: We present theoretically the thermal Hall effect of magnons in a\nferromagnetic lattice with a Kekul\\'e-O coupling (KOC) modulation and a\nDzyaloshinskii-Moriya interaction (DMI). Through a strain-based mechanism for\ninducing the KOC modulation, we identify four topological phases in terms of\nthe KOC parameter and DMI strength. We calculate the thermal magnon Hall\nconductivity ${\\kappa^{xy}}$ at low temperature in each of these phases. We\npredict an unconventional conductivity due to a non-zero Berry curvature\nemerging from band proximity effects in the topologically trivial phase. We\nfind sign changes of ${\\kappa^{xy}}$ as a function of the model parameters,\nassociated with the local Berry curvature and occupation probability of the\nbulk bands. Throughout, ${\\kappa^{xy}}$ can be easily tuned with external\nparameters such as the magnetic field and temperature."
    },
    {
        "anchor": "Quasiparticle Interference and Landau Level Spectroscopy in Graphene in\n  the presence of a Strong Magnetic Field: We present a calculation of the modulation in the Local Density Of electronic\nStates (LDOS) caused by an impurity in graphene in the presence of external\nmagnetic field. We focus on the spatial Fourier Transform (FT) of this\nmodulation around the impurity. The FT due to the low energy quasiparticles are\nfound to be nonzero over the reciprocal lattice corresponding to graphene. At\nthese lattice spots the FT exhibits well-defined features at wavevectors that\nare multiples of the inverse cyclotron orbit diameter (see Figure 2) and is cut\noff at the wavevector corresponding to the energy of observation. Scanning\nTunneling Spectroscopy (STS) on graphene and the energy-resolved FT fingerprint\nobtained therefrom may be used to observe the quasiparticle interference of\nDirac particles in graphene in the presence of magnetic field.",
        "positive": "Transport in T-shaped ballistic junction: We present studies of ballistic transport in three terminal T-shaped junction\nin a linear and non-linear regime. The floating electrode acts as a scatterer\nand modifies the conductance in a direct channel (between source and drain\nelectrode). In the low voltage limit, the conductance shows the Wigner\nthreshold effect and the bend resistance. A specific shape of the Wigner\nsingularities can be changed by applied voltage to the floating electrode as\nwell as by a shift of the Fermi level. The system also exhibits filtering\nproperties with current distribution between different modes propagating in the\njunction. Back action of current flowing in the direct channel on changes of\nthe voltage in the floating electrode is considered in the non-linear regime."
    },
    {
        "anchor": "Spin pumping in an altermagnet/normal metal bilayer: Altermagnetism is a subclass of antiferromagnetism that features\nspin-polarized electron bands of a non-relativistic origin despite the absence\nof a net magnetiation in the material. We here theoretically study spin pumping\nfrom an altermagnetic insulator into a normal metal. The symmetry properties of\nthe lattice and spin order of the altermagnet alters the magnon dispersion\ncompared to a conventional square lattice antiferromagnet. Nevertheless, the\npumped spin current turns out to be equal to the current which is pumped from a\nconventional antiferromagnet. This occurs so long that the magnetic field which\nsets the altermagnetic spins into precessional motion is spatially homogeneous.\nThese results show that while spin pumping is possible using altermagnets, the\naltermagnetic spin order does not readily leave unique fingerprints in the\npumped spin current. Our model provides a suitable starting point for\ninvestigating more complex models where finite momentum magnons contribute to\nspin pumping due to magnon-magnon interactions or where the magnetic field\ninducing spin pumping is spatially inhomogeneous.",
        "positive": "Phenomenology of current-induced skyrmion motion in antiferromagnets: We study current-driven skyrmion motion in uniaxial thin film\nantiferromagnets in the presence of the Dzyaloshinskii-Moriya interactions and\nin an external magnetic field. We phenomenologically include relaxation and\ncurrent-induced torques due to both spin-orbit coupling and spatially\ninhomogeneous magnetic textures in the equation for the N\\'eel vector of the\nantiferromagnet. Using the collective coordinate approach we apply the theory\nto a two-dimensional antiferromagnetic skyrmion and estimate the skyrmion\nvelocity under an applied DC electric current."
    },
    {
        "anchor": "Spin accumulation in ferromagnetic single-electron transistors in the\n  cotunneling regime: We propose a new method of direct detection of spin accumulation, which\novercomes problems of previous measurement schemes. A spin dependent current in\na single-electron transistor with ferromagnetic electrodes leads to spin\naccumulation on the metallic island. The resulting spin-splitting of the\nelectrochemical potentials of the island, because of an additional shift by the\ncharging energy, can be detected from the spacing between two resonances in the\ncurrent-voltage characteristics. The results were obtained in the framework of\na real-time diagrammatic approach which allows to study higher order\n(co-)tunneling processes in the strong nonequlibrium situation.",
        "positive": "Signatures of the $\u03c0$-mode anomaly in (1+1) dimensional\n  periodically-driven topological/normal insulator heterostructures: Akin to zero-mode anomalies, such as the chiral anomaly of edge states in\nquantum Hall effect, in this work, a pi-mode anomaly is proposed in a 1+1\ndimensional periodically-driven topological/normal insulator (TI/NI)\nheterostructure. Usually, when coupling in a background gauge field, the zero\nmodes on domain walls would provide an anomalous current term that is\neventually canceled by additional boundary contributions from the topological\nbulk, via the Callan-Harvey mechanism. This anomaly cancellation associated\nwith the generalization of bulk-boundary correspondence is called anomaly\ninflow. Through our photonic modeling and setup of the Floquet TI/NI\nheterostructure, for the first time, we experimentally observed the $\\pi$-mode\ndomain wall in certain driven frequencies, which is always attached to the\nreminiscent Floquet gauge that plays the vital role of an emergent background\nfield. Indeed, due to the possible emergence of Floquet gauge anomaly from the\ndriven topological bulk, the resultant $\\pi$-mode anomaly can be matched on the\ndriven interface between Floquet domains. Prospectively, we believe our\nprediction and observation could pave a new avenue on exploring anomalies in\nboth periodically-driven classical and quantum systems."
    },
    {
        "anchor": "Comment on \"Cooper instability of composite fermions\": We comment on the recent paper by Scarola, Park, and Jain [Nature v. 406, p.\n863 (2000); cond-mat/0012030] on a trial wavefunction calculation of pairing in\na fractional quantum Hall system at nu=5/2. We point out two errors that\ninvalidate the claimed calculations of a binding energy for Cooper pairs and of\nan energy gap for charged excitations.",
        "positive": "Self-organization phenomena at exciton condensation in quantum wells in\n  an inhomogeneous external potential: A theory of the separation of a system of indirect excitons into a condensed\nand a gaseous phases with the formation of regular patterns of alternating\nphases in inhomogeneous external fields is developed. The theory is applied to\nthe study of the non-uniform distribution of the exciton density in a double\nquantum well under a slot cut in a metallic electrode. It is shown that in a\ncertain range of exciton generation rates a chain of light emitting islands\nperiodically localized along the slot is developed. By creating a biased\nexternal potential along the slot the periodical pattern could be forced to\nmove along the slot. Also the structures of condensed phases distribution\narising at periodical external potential is considered."
    },
    {
        "anchor": "Current-induced atomic dynamics, instabilities, and Raman signals:\n  Quasi-classical Langevin equation approach: We derive and employ a semi-classical Langevin equation obtained from\npath-integrals to describe the ionic dynamics of a molecular junction in the\npresence of electrical current. The electronic environment serves as an\neffective non-equilibrium bath. The bath results in random forces describing\nJoule heating,current-induced forces including the non-conservative wind\nforce,dissipative frictional forces, and an effective Lorentz-like force due to\nthe Berry phase of the non-equilibrium electrons. Using a generic two-level\nmolecular model, we highlight the importance of both current-induced forces and\nJoule heating for the stability of the system. We compare the impact of the\ndifferent forces, and the wide-band approximation for the electronic structure\non our result. We examine the current-induced instabilities (excitation of\nrunaway \"waterwheel\" modes) and investigate the signature of these in the Raman\nsignals.",
        "positive": "Topological energy gaps in the [111]-oriented InAs/GaSb and GaSb/InAs\n  core-shell nanowires: The [111]-oriented InAs/GaSb and GaSb/InAs core-shell nanowires have been\nstudied by the $8\\times 8$ Luttinger-Kohn $\\vec{k}\\cdot\\vec{p}$ Hamiltonian to\nsearch for non-vanishing fundamental gaps between inverted electron and hole\nbands. We focus on the variations of the topologically nontrivial fundamental\ngap, the hybridization gap, and the effective gap with the core radius and\nshell thickness of the nanowires. The evolutions of all the energy gaps with\nthe structural parameters are shown to be dominantly governed by quantum size\neffects. With a fixed core radius, a topologically nontrivial fundamental gap\nexists only at intermediate shell thicknesses. The maximum gap is $\\sim 4.4$\nmeV for GaSb/InAs and $\\sim 3.5$ meV for InAs/GaSb core-shell nanowires, and\nfor the GaSb/InAs core-shell nanowires the gap persists over a wider range of\ngeometrical parameters. The intrinsic reason for these differences between the\ntwo types of nanowires is that in the shell the electron-like states of InAs is\nmore delocalized than the hole-like state of GaSb, while in the core the\nhole-like state of GaSb is more delocalized than the electron-like state of\nInAs, and both features favor stronger electron-hole hybridization. Since\nsimilar features of the electron- and hole-like states have been found in\nnanowires of other materials, it could serve as a common rule to put the\nhole-like state in the core while the electron-like state in the shell of a\ncore-shell nanowire to achieve better topological properties."
    },
    {
        "anchor": "Screening and Collective Modes in Disordered Graphene Antidot Lattices: The excitation spectrum and the collective modes of graphene antidot lattices\n(GALs) are studied in the context of a $\\pi$-band tight-binding model. The\ndynamical polarizability and dielectric function are calculated within the\nrandom phase approximation. The effect of different kinds of disorder, such as\ngeometric and chemical disorder, are included in our calculations. We highlight\nthe main differences of GALs with respect to single-layer graphene (SLG). Our\nresults show that, in addition to the well-understood bulk plasmon in doped\nsamples, inter-band plasmons appear in GALs. We further show that the static\nscreening properties of undoped and doped GALs are quantitatively different\nfrom SLG.",
        "positive": "Angular dependence of the interlayer coupling at the interface between\n  two dimensional materials 1T-PtSe$_2$ and graphene: We present a study by Scanning Tunneling Microscopy, supported by ab initio\ncalculations, of the interaction between graphene and monolayer\n(semiconducting) PtSe$_2$ as a function of the twist angle ${\\theta}$ between\nthe two layers. We analyze the PtSe$_2$ contribution to the hybrid interface\nstates that develop within the bandgap of the semiconductor to probe the\ninteraction. The experimental data indicate that the interlayer coupling\nincreases markedly with the value of ${\\theta}$, which is confirmed by ab\ninitio calculations. The moir\\'e patterns observed within the gap are\nconsistent with a momentum conservation rule between hybridized states, and the\nstrength of the hybridization can be qualitatively described by a perturbative\nmodel."
    },
    {
        "anchor": "Valley-based noise-resistant quantum computation using Si quantum dots: We devise a platform for noise-resistant quantum computing using the valley\ndegree of freedom of Si quantum dots. The qubit is encoded in two polarized\n(1,1) spin-triplet states with different valley compositions in a double\nquantum dot, with a Zeeman field enabling unambiguous initialization. A top\ngate gives a difference in the valley splitting between the dots, allowing\ncontrollable interdot tunneling between opposite valley eigenstates, which\nenables one-qubit rotations. Two-qubit operations rely on a stripline\nresonator, and readout on charge sensing. Sensitivity to charge and spin\nfluctuations is determined by intervalley processes and is greatly reduced as\ncompared to conventional spin and charge qubits. We describe a valley echo for\nfurther noise suppression.",
        "positive": "Generating a topological anomalous Hall effect in a non-magnetic\n  conductor: The ordinary Hall effect is driven by the Lorentz force, while its anomalous\ncounterpart occurs in ferromagnets. Here we show that the Berry curvature\nmonopole of non-magnetic 2D spin-3/2 holes leads to a novel Hall effect linear\nin an applied in-plane magnetic field B_x. There is no Lorentz force hence no\nordinary Hall effect, while all disorder contributions vanish to leading order\nin B_x. This intrinsic phenomenon, which we term the anomalous planar Hall\neffect (APHE), provides a non-quantized footprint of topological transport\ndirectly accessible in p-type semiconductors."
    },
    {
        "anchor": "Enhanced Andreev reflection in gapped graphene: We theoretically demonstrate unusual features of superconducting proximity\neffect in gapped graphene which presents a pseudospin symmetry-broken\nferromagnet with a net pseudomagnetization. We find that the presence of a band\ngap makes the Andreev conductance of graphene superconductor/pseudoferromagnet\n(S/PF) junction to behave similar to that of a graphene\nferromagnet-superconductor junction. The energy gap $\\Delta_N$ enhance the\npseudospin inverted Andreev conductance of S/PF junction to reach a limiting\nmaximum value for $\\Delta_N\\gg \\mu$, which depending on the bias voltage can be\nlarger than the value for the corresponding junction with no energy gap. We\nfurther demonstrate a damped-oscillatory behavior for the local density of\nstates of the PF region of S/PF junction and a long-range crossed Andreev\nreflection process in PF/S/PF structure with antiparallel alignment of\npseudomagnetizations of PFs, which confirm that, in this respect, the gapped\nnormal graphene behaves like a ferromagnetic graphene.",
        "positive": "Piezoconductivity of gated suspended graphene: We investigate the conductivity of graphene sheet deformed over a gate. The\neffect of the deformation on the conductivity is twofold: The lattice\ndistortion can be represented as pseudovector potential in the Dirac equation\nformalism, whereas the gate causes inhomogeneous density redistribution. We use\nthe elasticity theory to find the profile of the graphene sheet and then\nevaluate the conductivity by means of the transfer matrix approach. We find\nthat the two effects provide functionally different contributions to the\nconductivity. For small deformations and not too high residual stress the\ncorrection due to the charge redistribution dominates and leads to the\nenhancement of the conductivity. For stronger deformations, the effect of the\nlattice distortion becomes more important and eventually leads to the\nsuppression of the conductivity. We consider homogeneous as well as local\ndeformation. We also suggest that the effect of the charge redistribution can\nbe best measured in a setup containing two gates, one fixing the overall charge\ndensity and another one deforming graphene locally."
    },
    {
        "anchor": "Transport in Quantum Dots from the Integrability of the Anderson Model: In this work we exploit the integrability of the two-lead Anderson model to\ncompute transport properties of a quantum dot, in and out of equilibrium. Our\nmethod combines the properties of integrable scattering together with a\nLandauer-Buttiker formalism. Although we use integrability, the nature of the\nproblem is such that our results are not generically exact, but must only be\nconsidered as excellent approximations which nonetheless are valid all the way\nthrough crossover regimes.\n  The key to our approach is to identify the excitations that correspond to\nscattering states and then to compute their associated scattering amplitudes.\nWe are able to do so both in and out of equilibrium. In equilibrium and at zero\ntemperature, we reproduce the Friedel sum rule for an arbitrary magnetic field.\nAt finite temperature, we study the linear response conductance at the\nsymmetric point of the Anderson model, and reproduce Costi et al.'s numerical\nrenormalization group computation of this quantity. We then explore the\nout-of-equilibrium conductance for a near-symmetric Anderson model, and arrive\nat quantitative expressions for the differential conductance, both in and out\nof a magnetic field. We find the expected splitting of the differential\nconductance peak into two in a finite magnetic field, $H$. We determine the\nwidth, height, and position of these peaks. In particular we find for H >> T_k,\nthe Kondo temperature, the differential conductance has maxima of e^2/h\noccuring for a bias V close to but smaller than H. The nature of our\nconstruction of scattering states suggests that our results for the\ndifferential magneto-conductance are not merely approximate but become exact in\nthe large field limit.",
        "positive": "Collisionless Transport Close to a Fermionic Quantum Critical Point in\n  Dirac Materials: Quantum transport close to a critical point is a fundamental, but enigmatic\nproblem due to fluctuations, persisting at all length scales. We report the\nscaling of optical conductivity (OC) in the \\emph{collisionless} regime ($\\hbar\n\\omega \\gg k_B T$) in the vicinity of a relativistic quantum critical point,\nseparating two-dimensional ($d=2$) massless Dirac fermions from a fully gapped\ninsulator or superconductor. Close to such critical point gapless fermionic and\nbosonic excitations are strongly coupled, leading to a \\emph{universal}\nsuppression of the inter-band OC as well as of the Drude peak (while\nmaintaining its delta function profile) inside the critical regime, which we\ncompute to the leading order in $1/N_f$- and $\\epsilon$-expansions, where $N_f$\ncounts fermion flavor number and $\\epsilon=3-d$. Correction to the OC at such a\nnon-Gaussian critical point due to the long-range Coulomb interaction and\ngeneralizations of these scenarios to a strongly interacting three-dimensional\nDirac or Weyl liquid are also presented, which can be tested numerically and\npossibly from non-pertubative gauge-gravity duality, for example."
    },
    {
        "anchor": "Microscopic theory of Cooper pair beam splitters based on carbon\n  nanotubes: We analyze microscopically a Cooper pair splitting device in which a central\nsuperconducting lead is connected to two weakly coupled normal leads through a\ncarbon nanotube. We determine the splitting efficiency at resonance in terms of\ngeometrical and material parameters, including the effect of spin-orbit\nscattering. While the efficiency in the linear regime is limited to 50% and\ndecay exponentially as a function of the width of the superconducting region we\nshow that it can rise up to $\\sim 100%$ in the non-linear regime for certain\nregions of the stability diagram.",
        "positive": "An experimental demonstration of the memristor test: A simple and unambiguous test has been recently suggested [J. Phys. D:\nApplied Physics, 52, 01LT01 (2018)] to check experimentally if a resistor with\nmemory is indeed a memristor, namely a resistor whose resistance depends only\non the charge that flows through it, or on the history of the voltage across\nit. However, although such a test would represent the litmus test for claims\nabout memristors (in the ideal sense), it has yet to be applied widely to\nactual physical devices. In this paper, we experimentally apply it to a\ncurrent-carrying wire interacting with a magnetic core, which was recently\nclaimed to be a memristor (so-called `$\\Phi$ memristor') [J. Appl. Phys. 125,\n054504 (2019)]. The results of our experiment demonstrate unambiguously that\nthis `$\\Phi$ memristor' is not a memristor: it is simply an inductor with\nmemory. This demonstration casts further doubts that ideal memristors do\nactually exist in nature or may be easily created in the lab."
    },
    {
        "anchor": "Phonon-assisted decoherence in the production of polarization-entangled\n  photons in a single semiconductor quantum dot: We theoretically investigate the production of polarization-entangled photons\nthrough the biexciton cascade decay in a single semiconductor quantum dot. In\nthe intermediate state the entanglement is encoded in the polarizations of the\nfirst emitted photon and the exciton, where the exciton state can be\neffectively ``measured'' by the solid state environment through the formation\nof a lattice distortion. We show that the resulting loss of entanglement\nbecomes drastically enhanced if the phonons contributing to the lattice\ndistortion are subject to elastic scatterings at the device boundaries, which\nmight constitute a serious limitation for quantum-dot based entangled-photon\ndevices.",
        "positive": "Quantized escape and formation of edge channels at high Landau levels: We present nonlocal resistance measurements in an ultra high mobility two\ndimensional electron gas. Our experiments show that even at weak magnetic\nfields classical guiding along edges leads to a strong non local resistance on\nmacroscopic distances. In this high Landau level regime the transport along\nedges is dissipative and can be controlled by the amplitude of the voltage drop\nalong the edge. We report resonances in the nonlocal transport as a function of\nthis voltage that are interpreted as escape and formation of edge channels."
    },
    {
        "anchor": "Floquet states of Valley-Polarized Metal with One-way Spin or Charge\n  Transport in Zigzag Nanoribbons: Two-dimensional Floquet systems consisting of irradiated valley-polarized\nmetal are investigated. For the corresponding static systems, we consider two\ngraphene models of valley-polarized metal with either a staggered sublattice or\nuniform intrinsic spin-orbital coupling, whose Dirac point energies are\ndifferent from the intrinsic Fermi level. If the frequency of irradiation is\nappropriately designed, the largest dynamical gap (first-order dynamical gap)\nopens around the intrinsic Fermi level. In the presence of the irradiation, two\ntypes of edge state appear at the zigzag edge of semi-infinite sheet with\nenergy within the first-order dynamical gap: the Floquet edge states and the\nstrongly localized edge states. In narrow zigzag nanoribbons, the Floquet edge\nstates are gapped out by the finite size effect, and the strongly localized\nedge states remain gapless. As a result, the conducting channels of the\nnanoribbons consist of the strongly localized edge states. Under the first and\nsecond model, the strongly localized edge states carry one-way spin polarized\nand one-way charge current around the intrinsic Fermi level, respectively.\nThus, the narrow zigzag nanoribbons of the first and second model have\nasymmetric spin and charge transmission rates, respectively. Quantum-transport\ncalculations predict sizable pumped currents of charge and spin, which could be\ncontrolled by the Fermi level.",
        "positive": "Interaction-Enhanced Topological Hall Effects in Strained Twisted\n  Bilayer Graphene: We analyze the effects of the long-range Coulomb interaction on the\ndistribution of Berry curvature among the bands near charge neutrality of\ntwisted bilayer graphene (TBG) closely aligned with hexagonal boron nitride\n(hBN). Due to the suppressed dispersion of the narrow bands, the band structure\nis strongly renormalized by electron-electron interactions, and thus, the\nassociated topological properties of the bands are sensitive to filling. Using\na Hartree formalism, we calculate the linear and nonlinear Hall conductivities,\nand find that for certain fillings, the remote bands contribute substantially\nto the Hall currents while the contribution from the central bands is\nsuppressed. In particular, we find that these currents are generically\nsubstantial near regions of energies where the bands are highly entangled with\neach other, often featuring doping-induced band inversions. Our results\ndemonstrate that topological transport in TBG/hBN is substantially modified by\nelectron-electron interactions, which offer a simple explanation to recent\nexperimental results."
    },
    {
        "anchor": "Absence of the anomalous Hall effect in planar Hall experiments: Recently, the planar Hall effect has attracted tremendous interest. In\nparticular, an in-plane magnetization can induce an anomalous planar Hall\neffect with a $2\\pi/3$ period for hexagon-warped energy bands. This effect is\nsimilar to the anomalous Hall effect resulting from an out-of-plane\nmagnetization. However, this anomalous planar Hall effect is absent in the\nplanar Hall experiments. Here, we explain its absence, by performing a\ncalculation that includes not only the Berry curvature mechanism as those in\nthe previous theories, but also the disorder contributions. The conventional\n$\\pi$-period planar Hall effect will occur if the mirror reflection symmetry is\nbroken, which buries the anomalous one. We show that an in-plane strain can\nenhance the anomalous Hall conductivity and changes the period from $2\\pi/3$ to\n$2\\pi$. We propose a scheme to extract the hidden anomalous planar Hall\nconductivity from the experimental data. Our work will be helpful in detecting\nthe anomalous planar Hall effect and could be generalized to understand\nmechanisms of the planar Hall effects in a wide range of materials.",
        "positive": "The Quantum Links of the Anyons and their Entanglement: In this paper, after a brief presentation of the physical 2+1 dimensional\nplace where the anyons evolve, there is established the links creation\nprobability for the anyons. The departure point is the celebrated Laughlin wave\nfunction. Then, two cases of quantum links are emphasized, considering two and\nthree anyons. In the first case a two qubits register is attached. The unitary\ntransformation (e.g. the UCNOT unitary transformation) can map not-entangled\nquantum states to the quantum and topological entangled states, as there are\nhighlighted in this paper for the two anyons link case. The six qubit register\nwhich is attached to the three anyons link is only shortly presented since it\nrepresents a work in progress. The topologic and quantum states are represented\nby ket vectors and correspondingly by diagrams."
    },
    {
        "anchor": "Hybrid surface waves in two-dimensional Rashba-Dresselhaus materials: We address the electromagnetic properties of two-dimensional electron gas\nconfined by a dielectric environment in the presence of both Rashba and\nDresselhaus spin-orbit interactions. It is demonstrated that off-diagonal\ncomponents of the conductivity tensor resulting from a delicate interplay\nbetween Rashba and Dresselhaus couplings lead to the hybridization of\ntransverse electric and transverse magnetic surface electromagnetic modes\nlocalized at the interface. We show that the characteristics of these hybrid\nsurface waves can be controlled by additional intense external off-resonant\ncoherent pumping.",
        "positive": "Quantum metasurfaces with periodic arrays of $\u039b$-emitters: We study theoretically the optical response of a monolayer comprizing\nregularly spaced quantum emitters with a doublet in the ground state (the\nso-called $\\Lambda$-emitters). The emitters' self-action through the retarded\ndipole-dipole interaction provides a positive feedback, interplay of which with\nthe intrinsic nonlinearity of an isolated emitter, leads to an exotic optical\ndynamics of the system and prominent effects, such as multistability,\nself-oscillations, and quasi-chaotic behavior. %The bifurcation diagram\napproach is used to classify different scenarios of the system's behavior. In a\ncertain spectral domain, the monolayer operates as a bistable mirror. The\noptical response of the monolayer manifests high sensitivity to the doublet\nsplitting and relaxation within the doublet, suggesting the latter to be the\nkey parameters to tailor the monolayer optical response. These properties make\nsuch a system very promising for nanophotonic applications. We discuss the\nrelevance of the predicted nonlinear effects for nano-sized all-optical\ndevices."
    },
    {
        "anchor": "Proximity-induced superconductivity within the InAs/GaSb edge conducting\n  state: We experimentally investigate Andreev transport through the interface between\nan indium superconductor and the edge of the InAs/GaSb bilayer. To cover all\npossible regimes of InAs/GaSb spectrum, we study samples with 10 nm, 12 nm, and\n14 nm thick InAs quantum wells. For the trivial case of a direct band insulator\nin 10~nm samples, differential resistance demonstrates standard Andreev\nreflection. For InAs/GaSb structures with band inversion (12~nm and 14 nm\nsamples), we observe distinct low-energy structures, which we regard as direct\nevidence for the proximity-induced superconductivity within the\ncurrent-carrying edge state. For 14~nm InAs well samples, we additionally\nobserve mesoscopic-like resistance fluctuations, which are subjected to\nthreshold suppression in low magnetic fields.",
        "positive": "Parsing skin effect in a non-Hermitian spinless BHZ-like model: This work comprehensively investigates the non-Hermitian skin effect (NHSE)\nin a spinless Bernevig-Hughes-Zhang (BHZ)-like model in one dimension. It is\ngenerally believed that a system with non-reciprocal hopping amplitudes\ndemonstrates NHSE. However, we show that there are exceptions, and more\nin-depth analyses are required to decode the presence of NHSE or its variants\nin a system. The fascinating aspects of our findings, depending on the\ninclusion of non-reciprocity in the inter-orbital hopping terms, concede the\nexistence of conventional or bi-directional NHSE and even a surprising absence\nof NHSE. The topological properties and the (bi-orthogonal) bulk-boundary\ncorrespondence, enumerated via computation of the (complex) Berry phase, the\nwinding number, and spatial localization of the edge modes, highlight the\ntopological phase transitions occurring therein. Further, to facilitate a\nstructured discussion of the non-Hermitian model, we split the results into PT\nsymmetric and non-PT symmetric cases with a view to comparing the two."
    },
    {
        "anchor": "Magnetic dynamics from intrinsic spin-orbit torques in non-collinear\n  anti-ferromagnets: Using a pure electric current to control kagome non-collinear\nanti-ferromagnets is expected to be superior to ferromagnets and\n$\\mathcal{PT}$-symmetric anti-ferromagnets in information storage and\nprocessing. However, a full description of the magnetic dynamics of the\nnon-collinear anti-ferromagnetism driven by a pure electric current is still\nlacking, in particular, on intrinsic (i.e., without using external magnetic\nfields or external spin currents) spin-orbit torques. In this work, by\nassembling multiple microscopic models and theoretical approaches, we\nself-consistently describe the relations among the electronic structure,\nmagnetic structure, spin accumulations, and intrinsic spin-orbit torques, in\nthe magnetic dynamics of a non-collinear anti-ferromagnet driven by a pure\nelectric current. Our calculation can yield a critical current density\ncomparable with those in the experiments. The full description will be helpful\nfor future applications of non-collinear anti-ferromagnets.",
        "positive": "Fast charge sensing of Si/SiGe quantum dots via a high-frequency\n  accumulation gate: Quantum dot arrays are a versatile platform for the implementation of spin\nqubits, as high-bandwidth sensor dots can be integrated with single-, double-\nand triple-dot qubits yielding fast and high-fidelity qubit readout. However,\nfor undoped silicon devices, reflectometry off sensor ohmics suffers from the\nfinite resistivity of the two-dimensional electron gas (2DEG), and alternative\nreadout methods are limited to measuring qubit capacitance, rather than qubit\ncharge. By coupling a surface-mount resonant circuit to the plunger gate of a\nhigh-impedance sensor, we realized a fast charge sensing technique that is\ncompatible with resistive 2DEGs. We demonstrate this by acquiring at high speed\ncharge stability diagrams of double- and triple-dot arrays in Si/SiGe\nheterostructures as well as pulsed-gate single-shot charge and spin readout\nwith integration times as low as 2.4 $\\mu$s."
    },
    {
        "anchor": "Localized surface resonances of J-aggregate nanostructures: Metallic nanostructures are able to concentrate light into volumes far below\nthe diffraction limit. Here we show, by accurate scattering calculations, that\nnanostructures obtained from thin films of J-aggregate dyes, concentrate the\nelectromagnetic field at optical frequencies. Moreover, in contrast to metal\nnanoparticles, these molecular aggregates display highly attractive nonlinear\noptical properties that can be exploited for the realization of ultracompact\ndevices for switching light by light on the nanoscale without the need of\nadditional nonlinear materials. These results open new perspectives in\nplasmonic based nanophotonics.",
        "positive": "Thermoelectric properties of molecular nanostructures: We use the concept of resonant tunneling to calculate the thermopower of\nmolecular nanosystems. It turns out that the sign of the thermovoltage under\nresonant tunneling conditions depends sensitively on the participating\nmolecular orbital, and one finds a sign change when the transport channel\nswitches from the highest occupied molecular orbital to the lowest unoccupied\nmolecular orbital. Comparing our results to recent experimental data obtained\nfor a BDT molecule contacted with an STM tip, we observe good agreement."
    },
    {
        "anchor": "Electron dephasing near zero temperature: an experimental review: The behavior of the electron dephasing time near zero temperature,\n$\\tau_\\phi^0$, has recently attracted vigorous attention. This renewed interest\nis primarily concerned with whether $\\tau_\\phi^0$ should reach a finite or an\ninfinite value as $T \\to$ 0. While it is accepted that $\\tau_\\phi^0$ should\ndiverge if there exists only electron-electron (electron-phonon) scattering,\nseveral recent measurements have found that $\\tau_\\phi^0$ depends only very\nweakly on temperature, if at all, when $T$ is sufficiently low. This article\ndiscusses the current experimental status of \"the saturation problem\", and\nconcludes that the origin(s) for this widely observed saturation are still\nunresolved.",
        "positive": "Nonequilibrium Green's Function Approach to Phonon Transport in\n  Defective Carbon Nanotubes: We have developed a new theoretical formalism for phonon transport in\nnanostructures using the nonequilibrium phonon Green's function technique and\nhave applied it to thermal conduction in defective carbon nanotubes. The\nuniversal quantization of low-temperature thermal conductance in carbon\nnanotubes can be observed even in the presence of local structural defects such\nas vacancies and Stone-Wales defects, since the long wavelength acoustic\nphonons are not scattered by local defects. At room temperature, however,\nthermal conductance is critically affected by defect scattering since incident\nphonons are scattered by localized phonons around the defects. We find a\nremarkable change from quantum to classical features for the thermal transport\nthrough defective CNTs with increasing temperature."
    },
    {
        "anchor": "Temperature dependence of the conductivity of ballistic graphene: We investigate the temperature dependence of the conductivity in ballistic\ngraphene using Landauer transport theory. We obtain results which are\nqualitatively in agreement with many features recently observed in transport\nmeasurements on high mobility suspended graphene. The conductivity \\sigma at\nhigh temperature T and low density n grows linearly with T, while at high n we\nfind \\sigma ~ |n|^1/2 with negative corrections at small T due to the\nT-dependence of the chemical potential. At moderate densities the conductivity\nis a non-monotonic function of T and n, exhibiting a minimum at T=0.693 \\hbar v\n|n|^1/2 where v is the Fermi velocity. We discuss two kinds of Fabry-Perot\noscillations in short nanoribbons and their stability at finite temperatures.",
        "positive": "Nonlinear Valley Hall Effect: The valley Hall effect arises from valley contrasting Berry curvature and\nrequires inversion symmetry breaking. Here, we propose a nonlinear mechanism to\ngenerate a valley Hall current in systems with both inversion and time-reversal\nsymmetry, where the linear and second-order charge Hall currents vanish along\nwith the linear valley Hall current. We show that a second-order valley Hall\nsignal emerges from the electric field correction to the Berry curvature,\nprovided a valley-contrasting anisotropic dispersion is engineered. We\ndemonstrate the nonlinear valley Hall effect in tilted massless Dirac fermions\nin strained graphene and organic semiconductors. Our work opens up the\npossibility of controlling the valley degree of freedom in inversion symmetric\nsystems via nonlinear valleytronics."
    },
    {
        "anchor": "Ultrafast Electron Diffraction at Surfaces:From Nanoscale Heat Transport\n  to Driven Phase Transitions: Many fundamental processes of structural changes at surfaces occur on a pico-\nor femtosecond time scale. In order to study such ultra-fast processes, we have\ncombined modern surface science techniques with fs-laser pulses in a pump-probe\nscheme. Reflection high energy electron diffraction (RHEED) with grazing\nincident electrons ensures surface sensitivity for the probing electron pulses.\nUtilizing the Debye-Waller effect, we studied the nanoscale heat transport from\nan ultrathin film through a hetero-interface or the damping of vibrational\nexcitations in monolayer adsorbate systems on the lower ps-time scale. By means\nof spot profile analysis the different cooling rates of epitaxial Ge\nnanostructures of different size and strain state were determined. The\nexcitation and relaxation dynamics of a driven phase transition far away from\nthermal equilibrium is demonstrated using the In-induced (8x2) reconstruction\non Si(111). This Peierls-distorted surface charge density wave system exhibits\na discontinuous phase transition at 130 K from a (8x2) insulating ground state\nto (4x1) metallic excited state. Upon excitation by a fs-laser pulse, this\nstructural phase transition is non-thermally driven in only 700 fs into the\nexcited state. A small barrier of 40 meV hinders the immediate recovery of the\ngroundstate and the system is found in a metastable supercooled state for up to\nfew nanoseconds.",
        "positive": "Momentum and position detection in nanoelectromechanical systems beyond\n  Born and Markov approximations: We propose and analyze different schemes to probe the quantum nature of\nnanoelectromechanical systems (NEMS) by a tunnel junction detector. Using the\nKeldysh technique, we are able to investigate the dynamics of the combined\nsystem for an arbitrary ratio of $eV/\\hbar \\Omega$, where V is the applied bias\nof the tunnel junction and $\\Omega$ the eigenfrequency of the oscillator. In\nthis sense, we go beyond the Markov approximation of previous works where these\nparameters were restricted to the regime $eV/\\hbar \\Omega\\gg 1$. Furthermore,\nwe also go beyond the Born approximation because we calculate the finite\nfrequency current noise of the tunnel junction up to fourth order in the\ntunneling amplitudes. Interestingly, we discover different ways to probe both\nposition and momentum properties of NEMS. On the one hand, for a non-stationary\noscillator, we find a complex finite frequency noise of the tunnel junction. By\nanalyzing the real and the imaginary part of this noise separately, we conclude\nthat a simple tunnel junction detector can probe both position- and\nmomentum-based observables of the non-stationary oscillator. On the other hand,\nfor a stationary oscillator, a more complicated setup based on an\nAharonov-Bohm-loop tunnel junction detector is needed. It still allows us to\nextract position and momentum information of the oscillator. For this type of\ndetector, we analyze for the first time what happens if the energy scales $eV$,\n$\\hbar \\Omega$, and $k_B T$ take arbitrary values with respect to each other\nwhere T is the temperature of an external heat bath. Under these circumstances,\nwe show that it is possible to uniquely identify the quantum state of the\noscillator by a finite frequency noise measurement."
    },
    {
        "anchor": "Linear response of twisted bilayer graphene: continuum vs. tight-binding\n  models: We present a linear response calculation for twisted bilayer graphene. The\ncalculation is performed for both the continuum and tight-binding models, with\nthe aim of assessing the validity of the former. All qualitatively important\nfeatures previously reported by us [T. Stauber et al. Phys. Rev. Lett. 120,\n046801 (2018)] for the Drude matrix in the continuum model are also present in\nthe tight-binding calculation, with increasing quantitative agreement for\ndecreasing twist angle. These features include the chiral longitudinal magnetic\nmoment associated with plasmonic modes, and the anomalous counterflow around\nthe neutrality point, better interpreted as a paramagnetic response. We have\naddressed the differences between Drude and equilibrium response, and shown\nthat orbital paramagnetism is the equilibrium response to a parallel magnetic\nfield over a substantial doping region around the neutrality point. Chirality\nalso makes the equilibrium response to exhibit a non trivial current structure\nassociated with the non-vertical character of interlayer bonds in the\ntight-binding calculation.",
        "positive": "A self-referenced single-electron quantized-current source: With the anticipated redefinition of the international system of units (SI)\nthe base units will be linked to fundamental constants of nature [1]. As for\nthe electrical base unit \"Ampere\", it will be linked to the elementary charge\ne, requiring a corresponding quantum standard [2, 3]. Many concepts for such a\nstandard have been investigated [4-14] relying on controlling the\ntime-dependent tunnelling of electrons. However, the stochastic nature of\nquantum mechanical tunnelling intrinsically evokes uncontrolled deviations from\nthe nominally quantized current. Alternatively, the counting of electrons [15,\n16] has been explored but is severely limited in current amplitude and\nuncertainty by the low detector bandwidth. The late M. Wulf proposed [17] that\nthis fundamental problem of electrical quantum metrology could be overcome by\ncombining serial single-electron pumps with charge detectors allowing the\ngeneration of a quantized current and the in-situ detection of its stochastic\ndeviations. Here, we experimentally demonstrate such quantized-current\ngeneration with in-situ detection of tunnelling errors at low frequencies and a\nreduction of the total current uncertainty by more than one order of magnitude.\nAfter frequency scaling this should enable a validated primary standard for the\nredefined SI base unit Ampere."
    },
    {
        "anchor": "Chiral topological insulator of magnons: We propose a magnon realization of 3D topological insulator in the AIII\n(chiral symmetry) topological class. The topological magnon gap opens due to\nthe presence of Dzyaloshinskii-Moriya interactions. The existence of the\ntopological invariant is established by calculating the bulk winding number of\nthe system. Within our model, the surface magnon Dirac cone is protected by the\nsublattice chiral symmetry. By analyzing the magnon surface modes, we confirm\nthat the backscattering is prohibited. By weakly breaking the chiral symmetry,\nwe observe the magnon Hall response on the surface due to opening of the gap.\nFinally, we show that by changing certain parameters the system can be tuned\nbetween the chiral topological insulator (mcTI), three dimensional magnon\nanomalous Hall (3D-mAH), and Weyl magnon phases.",
        "positive": "Non-Hermitian exceptional Landau quantization in electric circuits: Alternating current RLC electric circuits form an accessible and highly\ntunable platform simulating Hermitian as well as non-Hermitian (nH) quantum\nsystems. We propose here a circuit realization of nH Dirac and Weyl\nHamiltonians subject to time-reversal invariant pseudo-magnetic field, enabling\nthe exploration of novel nH physics. We identify the low-energy physics with a\ngeneric real energy spectrum from the nH Landau quantization of exceptional\npoints and rings, which can avoid the nH skin effect and provides a physical\nexample of a quasiparticle moving in the complex plane. Realistic detection\nschemes are designed to probe the flat energy bands, sublattice polarization,\nedge states protected by a nH energy-reflection symmetry, and a characteristic\nnodeless probability distribution."
    },
    {
        "anchor": "Quadrupolar excitons in a tunnel-coupled van der Waals heterotrilayer: Strongly bound excitons and many-body interactions between them determine\nlight-matter interactions in van der Waals (vdW) heterostructures of 2D\nsemiconductors. Unlike fundamental particles, quasiparticles in condensed\nmatter, such as excitons, can be tailored to alter their interactions and\nrealize emergent quantum phases. Here, using a WS$_2$/WSe$_2$/WS$_2$\nheterotrilayer, we create a quantum superposition of oppositely oriented\ndipolar excitons - a quadrupolar exciton - wherein an electron is\nlayer-hybridized in WS$_2$ layers while the hole localizes in WSe$_2$. In\ncontrast to dipolar excitons, symmetric quadrupolar excitons only redshift in\nan out-of-plane electric field, consistent with ab initio calculations,\nregaining dipolar characteristics at higher fields. Electric field tunes the\nhybridization and allows for lifetime control through modification of the\nexcitonic wavefunction. Lack of density-dependent blue shift of heterotrilayer\nexcitons compared to dipolar excitons is consistent with quadrupolar\ninteractions. Our results present vdW heterotrilayers as a field-tunable\nplatform to engineer light-matter interactions and explore quantum phase\ntransitions between spontaneously ordered many-exciton phases.",
        "positive": "Nonlinear and nonreciprocal transport effects in untwinned thin films of\n  ferromagnetic Weyl metal SrRuO$_3$: The identification of distinct charge transport features, deriving from\nnontrivial bulk band and surface states, has been a challenging subject in the\nfield of topological systems. In topological Dirac and Weyl semimetals,\nnontrivial conical bands with Fermi-arc surface states give rise to negative\nlongitudinal magnetoresistance due to chiral anomaly effect and unusual\nthickness dependent quantum oscillation from Weyl-orbit effect, which were\ndemonstrated recently in experiments. In this work, we report the experimental\nobservations of large nonlinear and nonreciprocal transport effects for both\nlongitudinal and transverse channels in an untwinned Weyl metal of SrRuO$_3$\nthin film grown on a SrTiO$_{3}$ substrate. From rigorous measurements with\nbias current applied along various directions with respect to the crystalline\nprincipal axes, the magnitude of nonlinear Hall signals from the transverse\nchannel exhibits a simple sin$\\alpha$ dependence at low temperatures, where\n$\\alpha$ is the angle between bias current direction and orthorhombic\n[001]$_{\\rm o}$, reaching a maximum when current is along orthorhombic\n[1-10]$_{\\rm o}$. On the contrary, the magnitude of nonlinear and nonreciprocal\nsignals in the longitudinal channel attains a maximum for bias current along\n[001]$_{\\rm o}$, and it vanishes for bias current along [1-10]$_{\\rm o}$. The\nobserved $\\alpha$-dependent nonlinear and nonreciprocal signals in longitudinal\nand transverse channels reveal a magnetic Weyl phase with an effective Berry\ncurvature dipole along [1-10]$_{\\rm o}$ from surface states, accompanied by 1D\nchiral edge modes along [001]$_{\\rm o}$."
    },
    {
        "anchor": "Accumulation of spin-polarized states of charge carriers and a\n  spintronic battery: Spin valves based on materials in which the spin-flip is suppressed by the\nspatial separation of charge carriers, while maintaining electric neutrality in\nthe valve volume, are considered. The possibility of using these valves as\nelectric batteries is discussed. It is shown that if the potential difference\nacross the valve is controlled, incommensurability effects such as the \"devil's\nstaircase\" may be expected, which are associated with the Coulomb interaction\nand redistribution of electrons occurring while the battery is charged and\ndischarged. The effects of the emergence and vanishing of spontaneous spin\npolarization of conduction electrons with a change in the Fermi level in the\nvalve are predicted. Such spin valves can also be used in implementing\nspintronic memory cells, supercapacitors, and similar devices.",
        "positive": "Charge Density Waves in Exfoliated Thin Films of Van der Waals Materials: A number of the charge-density-wave materials reveal a transition to the\nmacroscopic quantum state around 200 K. We used graphene-like mechanical\nexfoliation of titanium diselenide crystals to prepare a set of films with\ndifferent thicknesses. The transition temperature to the charge-density-wave\nstate was determined via modification of Raman spectra of titanium diselenide\nfilms. It was established that the transition temperature can increase from its\nbulk value to ~240 K as the thickness of the van-der-Waals films reduces to the\nnanometer range. The obtained results are important for the proposed\napplications of such materials in the collective-state information processing,\nwhich require room-temperature operation."
    },
    {
        "anchor": "Noise and Thermal Depinning of Wigner Crystals: We examine changes in the depinning threshold and conduction noise\nfluctuations for driven Wigner crystals in the presence of quenched disorder.\nAt low temperatures there is a well defined depinning threshold and a strong\npeak in the noise power with $1/f$ noise characteristics. At higher\ntemperatures, the depinning threshold shifts to lower drives and the noise,\nwhich is also reduced in power, becomes more white in character. At lower\ntemperatures, a washboard frequency appears when the system depins elastically\nor forms a moving smectic state; however, this washboard signal is strongly\nreduced for higher temperatures and completely disappears above the melting\ntemperature of a system without quenched disorder. Our results are in good\nagreement with recent transport and noise studies for systems where electron\ncrystal depinning is believed to arise, and also show how noise can be used to\ndistinguish between crystal, glass, and liquid phases.",
        "positive": "Transient spin dynamics in a single-molecule magnet: We explore the limitations and validity of semi-classically formulated spin\nequations of motion. Using a single-molecule magnet as a test model, we employ\nthree qualitatively different approximation schemes. From a microscopic model,\nwe derive a generalized spin equation of motion in which the parameters have a\nnon-local time-dependence. This dynamical equation is simplified to the\nLandau-Lifshitz-Gilbert equation with i) time-dependent, and ii)\ntime-independent parameters. We show that transient dynamics is essentially\nnon-existing in the latter approximation, while the former breaks down in the\nregime of strong coupling between the spin and the itinerant electrons."
    },
    {
        "anchor": "Non-Hermitian topological exciton-polariton corner modes: We theoretically study two-dimensional exciton-polariton lattices and predict\nthat non-Hermitian topological corner modes can be formed under non-resonant\npumping. As a generalization of the non-Hermitian skin effect, all eigenstates\nare localized at the two corners in our model. This is also a higher\ndimensional topology compared to other proposals in exciton-polariton systems\nand we find that it allows propagating signals in the bulk of the system to\ntravel around defects, which is not possible in one-dimensional topological\nlattices or two-dimensional lattices with Hermitian edge states. Furthermore,\nas all polariton states are localized away from an excitation spot, the system\noffers an opportunity for more accurate measurement of the polariton-polariton\ninteraction strength as the pump-induced exciton-reservoir is spatially\nseparated from all polariton states.",
        "positive": "Next-nearest-neighbor Tight-binding Model of Plasmons in Graphene: In this paper we investigate the influence of the next-nearest-neighbor\ncoupling of tight-binding model of graphene on the spectrum of plasmon\nexcitations. The nearest-neighbor tight-binding model was previously used to\ncalculate plasmon spectrum in the next paper [1]. We expand the previous\nresults of the paper by the next-nearest-neighbor tight-binding model. Both\nmethods are based on the numerical calculation of the dielectric function of\ngraphene and loss function. Here we compare plasmon spectrum of the\nnext-nearest and nearest-neighbor tight-binding models and find differences\nbetween plasmon dispersion of two models."
    },
    {
        "anchor": "Influences of the dissipative topological edge state on quantized\n  transport in MnBi2Te4: The beauty of quantum Hall (QH) effect is the metrological precision of Hall\nresistance quantization that originates from the topological edge states.\nUnderstanding the factors that lead to quantization breakdown not only provides\nimportant insights on the nature of the topological protection of these edge\nstates, but is beneficial for device applications involving such quantized\ntransport. In this work, we combine conventional transport and real space\nconductivity mapping to investigate whether the quantization breakdown is tied\nto the disappearance of edge state in the hotly studied MnBi2Te4 system. Our\nexperimental results unambiguously show that topological edge state does exist\nwhen quantization breakdown occurs. Such edge state is dissipative in nature\nand could lead to a quantization breakdown due to its diffusive character\ncausing overlapping with bulk and other edge states in real devices. Our\nfindings bring attentions to issues that are generally inaccessible in the\ntransport study of QH, but can play important roles in practical measurements\nand device applications.",
        "positive": "Quantized Landau level spectrum and its density dependence: Scanning tunneling microscopy and spectroscopy in magnetic field was used to\nstudy Landau quantization in graphene and its dependence on charge carrier\ndensity. Measurements were carried out on exfoliated graphene samples deposited\non a chlorinated SiO2 thermal oxide which allowed observing the Landau level\nsequences characteristic of single layer graphene while tuning the density\nthrough the Si backgate. Upon changing the carrier density we find abrupt jumps\nin the Fermi level after each Landau level is filled. Moreover, the Landau\nlevel spacing shows a marked increase at low doping levels, consistent with an\ninteraction-induced renormalization of the Dirac cone."
    },
    {
        "anchor": "Magnetization reversal by uniform rotation (Stoner-Wohlfarth model) in\n  f.c.c. cobalt nanoparticles: The combination of high sensitive superconducting quantum interference device\n(SQUID) with high quality nanoparticles allowed to check the simplest classical\nmodel describing the magnetisation reversal by uniform rotation which were\nproposed more than 50 years ago by Neel, Stoner and Wohlfarth. The micrometer\nsized SQUIDs were elaborated by electron beam lithography and the nanoparticles\nwere synthesised by arc-discharge. The measured angular dependence of switching\nfields of nearly all f.c.c. Co nanoparticles revealed a dominating uniaxial\nmagnetic anisotropy. This result suggests that twin boundaries and stacking\nfaults strongly alter the cubic magnetocrystalline anisotropy leading to\ndominating uniaxial anisotropy. However, few particles were sufficiently\n\"perfect\" in order to show a more complex switching field surface and a field\npath dependence of the switching field which is the important signature of the\ncubic magnetocrystalline anisotropy.",
        "positive": "Determining surface properties with bimodal and multimodal AFM: Conventional dynamic atomic force microscopy (AFM) can be extended to bimodal\nand multimodal AFM in which the cantilever is simultaneously excited at two ore\nmore resonance frequencies. Such excitation schemes result in one additional\namplitude and phase images for each driven resonance, and potentially convey\nmore information about the surface under investigation. Here we present a\ntheoretical basis for using this information to approximate the parameters of a\ntip-surface interaction model. The theory is verified by simulations with added\nnoise corresponding to room-temperature measurements."
    },
    {
        "anchor": "Third-order optical conductivity of an electron fluid: We derive the nonlinear optical conductivity of an isotropic electron fluid\nat frequencies below the interparticle collision rate. In this regime, governed\nby hydrodynamics, the conductivity acquires a universal form at any\ntemperature, chemical potential, and spatial dimension. We show that the\nnonlinear response of the fluid to a uniform field is dominated by the\nthird-order conductivity tensor $\\sigma^{(3)}$ whose magnitude and temperature\ndependence differ qualitatively from those in the conventional kinetic regime\nof higher frequencies. We obtain explicit formulas for $\\sigma^{(3)}$ for Dirac\nmaterials such as graphene and Weyl semimetals. We make predictions for the\nthird-harmonic generation, renormalization of the collective-mode spectrum, and\nthe third-order circular magnetic birefringence experiments.",
        "positive": "Optical selection rules for excitonic Rydberg series in the massive\n  Dirac cones of hexagonal 2D materials: We investigate the optical transition selection rules for excitonic Rydberg\nseries formed in massive Dirac cones. The entanglement of the exciton envelop\nfunction with the pseudospin texture leads to anomalous selection rules for\none-photon generation of excitons, where $d$-orbitals can be excited with the\nopposite helicity selection rule from the $s$-orbitals in a given valley. The\ntrigonal warping effects in realistic hexagonal lattices further renders more\nexcited states bright, where $p$-orbitals can also be accessed by one-photon\nexcitation with the opposite valley selection rules to the $s$-orbitals. The\none-photon generation of exciton in the various states and the intra-excitonic\ntransition between these states are both dictated by the discrete in-plane\nrotational symmetry of the lattices, and our results show that in hexagonal 2D\nmaterials the symmetry allowed transitions are enabled when trigonal warping\neffects are included in the massive Dirac fermion model. In monolayer\ntransition metal dichalcogenides where excitons can be generated by visible\nlight and intra-excitonic transitions can be induced by infrared light, we give\nthe strength of these optical transitions, estimated using modified\nhydrogen-like envelope functions combined with the optical transition matrix\nelements between the Bloch states calculated at various $k$ points."
    },
    {
        "anchor": "Observation of Conductance Quantization in InSb Nanowire Networks: Majorana Zero Modes (MZMs) are prime candidates for robust topological\nquantum bits, holding a great promise for quantum computing. Semiconducting\nnanowires with strong spin orbit coupling offers a promising platform to\nharness one-dimensional electron transport for Majorana physics. Demonstrating\nthe topological nature of MZMs relies on braiding, accomplished by moving MZMs\naround each other in a certain sequence. Most of the proposed Majorana braiding\ncircuits require nanowire networks with minimal disorder. Here, the electronic\ntransport across a junction between two merged InSb nanowires is studied to\ninvestigate how disordered these nanowire networks are. Conductance\nquantization plateaus are observed in all contact pairs of the epitaxial InSb\nnanowire networks; the hallmark of ballistic transport behavior.",
        "positive": "Fingerprints of the Magnetic Polaron in Nonequilibrium Electron\n  Transport through a Quantum Wire Coupled to a Ferromagnetic Spin Chain: We study nonequilibrium quantum transport through a mesoscopic wire coupled\nvia local exchange to a ferromagnetic spin chain. Using the Keldysh formalism\nin the self-consistent Born approximation, we identify fingerprints of the\nmagnetic polaron state formed by hybridization of electronic and magnon states.\nBecause of its low decoherence rate, we find coherent transport signals. Both\nelastic and inelastic peaks of the differential conductance are discussed as a\nfunction of external magnetic fields, the polarization of the leads and the\nelectronic level spacing of the wire."
    },
    {
        "anchor": "Topology vs. Anderson localization: non-perturbative solutions in one\n  dimension: We present an analytic theory of quantum criticality in quasi one-dimensional\ntopological Anderson insulators. We describe these systems in terms of two\nparameters $(g,\\chi)$ representing localization and topological properties,\nrespectively. Certain critical values of $\\chi$ (half-integer for $\\Bbb{Z}$\nclasses, or zero for $\\Bbb{Z}_2$ classes) define phase boundaries between\ndistinct topological sectors. Upon increasing system size, the two parameters\nexhibit flow similar to the celebrated two parameter flow of the integer\nquantum Hall insulator. However, unlike the quantum Hall system, an exact\nanalytical description of the entire phase diagram can be given in terms of the\ntransfer-matrix solution of corresponding supersymmetric non-linear\nsigma-models. In $\\Bbb{Z}_2$ classes we uncover a hidden supersymmetry, present\nat the quantum critical point.",
        "positive": "Anomalous Behaviour in the Magneto-Optics of a Gapped Topological\n  Insulator: The Dirac fermions at the surface of a topological insulator can be gapped by\nintroducing magnetic dopants. Alternatively, in an ultra-thin slab with\nthickness on the order of the extent of the surface states, both the top and\nbottom surface states acquire a common gap value ($\\Delta$) but with opposite\nsign. In a topological insulator, the dominant piece of the Hamiltonian\n($\\hat{H}$) is of a relativistic nature. A subdominant non-relativistic piece\nis also present and in an external magnetic field ($B$) applied perpendicular\nto the surface, the $N=0$ Landau level is no longer at zero energy but is\nshifted to positive energy by the Schr{\\\"o}dinger magnetic energy. When a gap\nis present, it further shifts this level down by $-\\Delta$ for positive\n$\\Delta$ and up by $|\\Delta|$ for a negative gap. This has important\nconsequences for the magneto-optical properties of such systems. In particular,\nat charge neutrality, the lowest energy transition displays anomalous\nnon-monotonic behaviour as a function of $B$ in both its position in energy and\nits optical spectral weight. The gap can also have a profound impact on the\nspectral weight of the interband lines and on corresponding structures in the\nreal part of the dynamical Hall conductivity. Conversely, the interband\nbackground in zero field remains unchanged by the non-relativistic term in\n$\\hat{H}$ (although its onset frequency is modified)."
    },
    {
        "anchor": "Entanglement smectic and stripe order: Spontaneous symmetry breaking and more recently entanglement are two\ncornerstones of quantum matter. We introduce the notion of anisotropic\nentanglement ordered phases, where the spatial profile of spin-pseudospin\nentanglement spontaneously lowers the four-fold rotational symmetry of the\nunderlying crystal to a two-fold one, while the charge density retains the full\nsymmetry. The resulting phases, which we term $\\textit{entanglement smectic}$\nand $\\textit{entanglement stripe}$, exhibit a rich Goldstone mode spectrum and\na set of phase transitions as a function of underlying anisotropies. We discuss\nexperimental consequences of such anisotropic entanglement phases\ndistinguishing them from more conventional charge or spin stripes. Our\ndiscussion of this interplay between entanglement and spontaneous symmetry\nbreaking focuses on multicomponent quantum Hall systems realizing textured\nWigner crystals, as may occur in graphene or possibly also in moir\\'e systems,\nhighlighting the rich landscape and properties of possible entanglement ordered\nphases.",
        "positive": "Higher vortexability: zero field realization of higher Landau levels: The rise of moir\\'{e} materials has led to experimental realizations of\ninteger and fractional Chern insulators in small or vanishing magnetic fields.\nAt the same time, a set of minimal conditions sufficient to guarantee a Abelian\nfractional state in a flat band were identified, namely \"ideal\" or \"vortexable\"\nquantum geometry. Such vortexable bands share essential features with the\nlowest Landau level, while excluding the need for more fine-tuned aspects such\nas flat Berry curvature. A natural and important generalization is to ask if\nsuch conditions can be extended to capture the quantum geometry of higher\nLandau levels, particularly the first (1LL), where non-Abelian states at $\\nu =\n1/2,2/5$ are known to be competitive. The possibility of realizing these states\nat zero magnetic field , and perhaps even more exotic ones, could become a\nreality if we could identify the essential structure of the 1LL in Chern bands.\nIn this work, we introduce a precise definition of 1LL quantum geometry, along\nwith a figure of merit that measures how closely a given band approaches the\n1LL. We apply the definition to identify two models with 1LL structure -- a toy\nmodel of double bilayer twisted graphene and a more realistic model of strained\nBernal graphene."
    },
    {
        "anchor": "Electron energy relaxation in the presence of magnetic impurities: We study inelastic electron-electron scattering mediated by the exchange\ninteraction of electrons with magnetic impurities, and find the kernel of the\ncorresponding two-particle collision integral. In a wide region of parameters,\nthe kernel K is proportional to the inverse square of the transferred energy,\n$K\\propto J^4/E^2$. The exchange constant J is renormalized due to the Kondo\neffect, yielding an additional weak dependence of K on the energies of the\ncolliding electrons. At small energy transfers, the $1/E^2$ divergence is cut\noff; the cut-off energy is determined by the dynamics of the impurity spins.\nThe obtained results may provide a quantitative explanation of the experiments\nof Pothier et al. [Phys. Rev. Lett. 79, 3490 (1997)] on anomalously strong\nenergy relaxation in short metallic wires.",
        "positive": "Adjustable quantum interference oscillations in Sb-doped Bi2Se3\n  topological insulator nanoribbons: Topological insulator (TI) nanoribbons (NRs) provide a unique platform for\ninvestigating quantum interference oscillations combined with topological\nsurface states. One-dimensional subbands formed along the perimeter of a TI NR\ncan be modulated by an axial magnetic field, exhibiting Aharonov-Bohm (AB) and\nAltshuler-Aronov-Spivak (AAS) oscillations of magnetoconductance (MC). Using\nSb-doped Bi2Se3 TI NRs, we found that the relative amplitudes of the two\nquantum oscillations can be tuned by varying the channel length, exhibiting\ncrossover from quasi-ballistic to diffusive transport regimes. The AB and AAS\noscillations were discernible even for a 70 micrometer long channel, while only\nthe AB oscillations were observed for a short channel. Analyses based on\nensemble-averaged fast Fourier transform of MC curves revealed exponential\ntemperature dependences of the AB and AAS oscillations, from which the\ncircumferential phase-coherence length and thermal length were obtained. Our\nobservations indicate that the channel length in a TI NR can be a useful\ncontrol knob for tailored quantum interference oscillations, especially for\ndeveloping topological hybrid quantum devices."
    },
    {
        "anchor": "Ballistic spin transport in exciton gases: Traditional spintronics relies on spin transport by charge carriers, such as\nelectrons in semiconductor crystals. This brings several complications: the\nPauli principle prevents the carriers from moving with the same speed; Coulomb\nrepulsion leads to rapid dephasing of electron flows. Spin-optronics is a\nvaluable alternative to traditional spintronics. In spin-optronic devices the\nspin currents are carried by electrically neutral bosonic quasi-particles:\nexcitons or exciton-polaritons. They can form highly coherent quantum liquids\nand carry spins over macroscopic distances. The price to pay is a finite\nlife-time of the bosonic spin carriers. We present the theory of exciton\nballistic spin transport which may be applied to a range of systems where\nbosonic spin transport has been reported, in particular, to indirect excitons\nin coupled GaAs/AlGaAs quantum wells. We describe the effect of spin-orbit\ninteraction of electrons and holes on the exciton spin, account for the Zeeman\neffect induced by external magnetic fields, long range and short range exchange\nsplittings of the exciton resonances. We also consider exciton transport in the\nnon-linear regime and discuss the definitions of exciton spin current,\npolarization current and spin conductivity.",
        "positive": "Lorentz Covariance of Dirac Electrons in Solids: Dielectric and\n  Diamagnetic Properties: We study the electrodynamics of Dirac electrons in solids (e.g., bismuth) by\ncomparing it with quantum electrodynamics (QED). It is shown that Lorentz\ncovariance associated with the Dirac electrons in solids results in a\nremarkable correlation between the dielectric and diamagnetic properties,\nleading to a significant enhancement in the permittivity directly linked to the\nwell-known phenomenon of large diamagnetism."
    },
    {
        "anchor": "Direct electronic measurement of the spin Hall effect: The generation, manipulation and detection of spin-polarized electrons in\nnanostructures define the main challenges of spin-based electronics[1]. Amongst\nthe different approaches for spin generation and manipulation, spin-orbit\ncoupling, which couples the spin of an electron to its momentum, is attracting\nconsiderable interest. In a spin-orbit-coupled system, a nonzero spin-current\nis predicted in a direction perpendicular to the applied electric field, giving\nrise to a \"spin Hall effect\"[2-4]. Consistent with this effect,\nelectrically-induced spin polarization was recently detected by optical\ntechniques at the edges of a semiconductor channel[5] and in two-dimensional\nelectron gases in semiconductor heterostructures[6,7]. Here we report\nelectrical measurements of the spin-Hall effect in a diffusive metallic\nconductor, using a ferromagnetic electrode in combination with a tunnel barrier\nto inject a spin-polarized current. In our devices, we observe an induced\nvoltage that results exclusively from the conversion of the injected spin\ncurrent into charge imbalance through the spin Hall effect. Such a voltage is\nproportional to the component of the injected spins that is perpendicular to\nthe plane defined by the spin current direction and the voltage probes. These\nexperiments reveal opportunities for efficient spin detection without the need\nfor magnetic materials, which could lead to useful spintronics devices that\nintegrate information processing and data storage.",
        "positive": "Field-tilt Anisotropy Energy in Quantum Hall Stripe States: Recently reported giant anisotropy in the longitudinal resistivity of a 2D\nelectron system with valence Landau level index $N \\ge 2$ has been interpreted\nas a signal of unidirectional charge density wave (UCDW) ground states. We\nreport on detailed Hartree-Fock calculations of the UCDW orientation energy\ninduced by a tilted magnetic field. We find that for current experimental\nsamples stripes are oriented perpendicular to the in-plane field, consistent\nwith experiment. For wider 2D electron systems we predict tilt-induced stripe\nstates with variable anisotropy energy sign."
    },
    {
        "anchor": "New approach for fabrication germanene with Dirac electrons preserved: A\n  first principle study: How to obtain germanene with Dirac electrons preserved is still an open\nchallenge. Here we report a sandwich-dehydrogenation approach, i.e., to\nfabricate germanene through dehydrogenating germanane in a sandwiched\nstructure. The dehydrogenation can spontaneously occur for the sandwiched\nstructure, which overcomes the problem of amorphization in the heating\ndehydrogenation approach. The obtained germanene preserve the Dirac electronic\nproperties very well. Moreover, the Fermi velocity of germanene can be\nefficiently manipulated through controlling the interlayer spacing between\ngermanane and the sandwiching surfaces. Our results indicate a guideline for\nfabrication of prefect two-dimensional materials.",
        "positive": "Coherent spin-valley oscillations in silicon: Electron spins in silicon quantum dots are excellent qubits because they have\nlong coherence times, high gate fidelities, and are compatible with advanced\nsemiconductor manufacturing techniques. The valley degree of freedom, which\nresults from the specific character of the Si band structure, is a unique\nfeature of electrons in Si spin qubits. However, the small difference in energy\nbetween different valley levels often poses a challenge for quantum computing\nin Si. Here, we show that the spin-valley coupling in Si, which enables\ntransitions between states with different spin and valley quantum numbers,\nenables coherent control of electron spins in Si. We demonstrate coherent\nmanipulation of effective single- and two-electron spin states in a Si/SiGe\ndouble quantum dot without ac magnetic or electric fields. Our results\nillustrate that the valley degree of freedom, which is often regarded as an\ninconvenience, can itself enable quantum manipulation of electron spin states."
    },
    {
        "anchor": "Calculation of electron transport in branched semiconductor\n  nanostructures using quantum network model: Electron transport in branched semiconductor nanostructures provides many\npossibilities for creating fundamentally new devices. We solve the problem of\nits calculation using a quantum network model. The proposed scheme consists of\nthree computational parts: S-matrix of the network junction, S-matrix of the\nnetwork in terms of its junctions' S-matrices, electric currents through the\nnetwork based on its S-matrix. To calculate the S-matrix of the network\njunction, we propose scattering boundary conditions in a clear\nintegro-differential form. As an alternative, we also consider the\nDirichlet-to-Neumann and Neumann-to-Dirichlet map methods. To calculate the\nS-matrix of the network in terms of its junctions' S-matrices, we obtain a\nnetwork combining formula. We find electrical currents through the network in\nthe framework of the Landauer$-$B\\\"uttiker formalism. Everywhere for\ncalculations, we use extended scattering matrices, which allows taking into\naccount correctly the contribution of tunnel effects between junctions. We\ndemonstrate the proposed calculation scheme by modeling nanostructure based on\ntwo-dimensional electron gas. For this purpose we offer a model of a network\nformed by smooth junctions with one, two and three adjacent branches. We\ncalculate the electrical properties of such a network (by the example of GaAs),\nformed by four junctions, depending on the temperature.",
        "positive": "The influence of single magnetic impurities on the conductance of\n  quantum microconstrictions: The nonlinear ballistic conductance of three-dimensional quantum\nmicroconstrictions, which contain magnetic impurities, is investigated. The\nnonlinear part of the conductance, which is due to the interaction of electrons\nwith magnetic impurities is obtained. The analytical results have been analyzed\nnumerically. It is shown that intensity of the Kondo anomaly in the conductance\nas the function of the applied voltage depends on the diameter of the\nconstriction and the positions of impurities."
    },
    {
        "anchor": "Current noise of the interacting resonant level model: We study the zero-frequency current noise of the interacting resonant level\nmodel for arbitrary bias voltages using a functional renormalization group\napproach. For this we extend the existing nonequilibrium scheme by deriving and\nsolving flow equations for the current-vertex functions. On-resonance\nartificial divergences of the latter found in lowest-order perturbation theory\nin the two-particle interaction are consistently removed. Away from resonance\nthey are shifted to higher orders. This allows us to gain a comprehensive\npicture of the current noise in the scaling limit. At high bias voltages, the\ncurrent noise exhibits a universal power-law decay, whose exponent is to\nleading order in the interaction identical to that of the current. The\neffective charge on resonance is analyzed in detail employing properties of the\nvertex correction. We find that it is only modified to second or higher order\nin the two-particle interaction.",
        "positive": "Full 2D Numerical Study of the Quantum Hall Skyrme Crystal: Spin textures arise in the effective action approach to the quantum Hall\neffect. Up to now these textures, also called Skyrmions, have been mainly\nstudied using approximations. Studies of its finite density form, the crystal,\nhave been limited to a given symmetry and tend ignore Skyrmion deformation.\nUsing a simulated annealing technique, adapted to problems with a long-range\ninteraction, we are able to present the first full 2D study of quantum Hall\nSkyrmions and the corresponding crystals. Our results show that only the\nSkyrmions with topological charge one and two are bound and that the Skyrme\ncrystal is probably a triangular lattice made of charge-two Skyrmions."
    },
    {
        "anchor": "Stacking transition in rhombohedral graphite: Few layer graphene (FLG) has been recently intensively investigated for its\nvariable electronic properties defined by a local atomic arrangement. While the\nmost natural layers arrangement in FLG is ABA (Bernal) stacking, a metastable\nABC (rhombohedral) stacking characterized by a relatively high energy barrier\ncan also occur. When both stacking occur in the same FLG device this results in\nin-plane heterostructure with a domain wall (DW). We show that ABC stacking in\nFLG can be controllably and locally turned into ABA stacking by two following\napproaches. In the first approach, Joule heating was introduced and the\ntransition was characterized by 2D-peak Raman spectra at a submicron spatial\nresolution. The observed transition was initiated at a small region and then\nthe DW controllably shifted until the entire device became ABA stacked. In the\nsecond approach, the transition was achieved by illuminating the ABC region\nwith a train of laser pulses of 790 nm wavelength, while the transition was\nvisualized by transmission electron microscopy in both diffraction and dark\nfield modes. Also, with this approach, a DW was visualized in the dark-field\nimaging mode, at a nanoscale spatial resolution.",
        "positive": "Route toward high-speed nano-magnonics: We study experimentally the possibility to utilize pulses of pure spin\ncurrent, produced via the nonlocal spin injection mechanism, to generate short\npackets of spin waves propagating in nanoscale magnetic waveguides. The\nspatially and time-resolved micro-focus Brillouin light scattering spectroscopy\nmeasurements demonstrate that the excitation by spin current results in\nextremely fast transient response, enabling efficient generation of short\nspin-wave packets with duration down to a few nanoseconds. The proposed method\nopens a route for the implementation of high-speed magnonic systems for\ntransmission and processing of information on the nanoscale."
    },
    {
        "anchor": "Multiple scattering of classical waves: from microscopy to mesoscopy and\n  diffusion: A tutorial discussion of the propagation of waves in random media is\npresented. In first approximation the transport of the multiple scattered waves\nis given by diffusion theory, but important corrections are present. These\ncorrections are calculated with the radiative transfer or Schwarzschild-Milne\nequation, which describes intensity transport at the ``mesoscopic'' level and\nis derived from the ``microscopic'' wave equation. A precise treatment of the\ndiffuse intensity is derived which automatically includes the effects of\nboundary layers. Effects such as the enhanced backscatter cone and imaging of\nobjects in opaque media are also discussed within this framework. In the second\npart the approach is extended to mesoscopic correlations between multiple\nscattered intensities which arise when scattering is strong. These correlations\narise from the underlying wave character. The derivation of correlation\nfunctions and intensity distribution functions is given and experimental data\nare discussed. Although the focus is on light scattering, the theory is also\napplicable to micro waves, sound waves and non-interacting electrons.",
        "positive": "Weak localization scattering lengths in epitaxial, and CVD graphene: Weak localization in graphene is studied as a function of carrier density in\nthe range from 1 x $10^{11}$\\,cm$^{-2}$ to 1.43 x $10^{13}$\\,cm$^{-2}$ using\ndevices produced by epitaxial growth onto SiC and CVD growth on thin metal\nfilm. The magnetic field dependent weak localization is found to be well fitted\nby theory, which is then used to analyse the dependence of the scattering\nlengths L$_\\varphi$, L$_i$, and L$_*$ on carrier density. We find no\nsignificant carrier dependence for L$_\\varphi$, a weak decrease for L$_i$ with\nincreasing carrier density just beyond a large standard error, and a\nn$^{-\\frac{1}{4}}$ dependence for L$_*$. We demonstrate that currents as low as\n0.01\\,nA are required in smaller devices to avoid hot-electron artefacts in\nmeasurements of the quantum corrections to conductivity."
    },
    {
        "anchor": "Decoherence in adiabatic quantum computation: We have studied the decoherence properties of adiabatic quantum computation\n(AQC) in the presence of in general non-Markovian, e.g., low-frequency, noise.\nThe developed description of the incoherent Landau-Zener transitions shows that\nthe global AQC maintains its properties even for decoherence larger than the\nminimum gap at the anticrossing of the two lowest energy levels. The more\nefficient local AQC, however, does not improve scaling of the computation time\nwith the number of qubits $n$ as in the decoherence-free case. The scaling\nimprovement requires phase coherence throughout the computation, limiting the\ncomputation time and the problem size n.",
        "positive": "Amplification of Hypersound in Graphene with degenerate energy\n  dispersion: Hypersound amplification/absorption of acoustic phonons in Graphene with\ndegenerate energy dispersion $\\varepsilon(p)$ near the Fermi level was\ntheoretically studied. For $k_{\\beta}T << 1$ and $ql >> 1$, the dependence of\nthe absorption coefficient $\\Gamma/\\Gamma_0$ on ${V_D\\over V_s}$ was studied\nwhere the results satisfied the Cerenkov effect. That is when ${V_D\\over V_s} >\n1$, an amplification was obtained but for ${V_D\\over V_s} < 1$, an absorption\nwas obtained which could lead to Acoustoelectric Effect (AE) in Graphene. A\nlinear dependence of the $\\Gamma/\\Gamma_0$ on $\\omega_q$ was observed where the\nresult obtianed qualitatively agreed with an experimentally observed\nacoustoelectric current in Graphene via the Weinrich relation. It is\ninteresting to note from this study that, frequencies above $10THz$ can be\nattained for $V_D = 1.1ms^{-1}$. This study permit the use of Graphene as\nhypersound phonon laser (SASER)."
    },
    {
        "anchor": "Spin-boson dynamics: A unified approach from weak to strong coupling: We present a novel approximation scheme to describe the influence of a\nharmonic bath on the dynamics of a two-level particle over almost the whole\nregime of temperatures and coupling to the environment, for a wide class of\nbath spectral densities. Starting from the exact path-integral solution for the\ntwo-level system density matrix, effective intra-blip correlations are fully\nincluded, while inter-blip and blip-sojourn interactions are considered up to\nfirst order. In the proper regimes, an excellent agreement with conventional\nperturbative approaches and ab-initio path-integral results is found.",
        "positive": "Resonant plasmonic detection of terahertz radiation in field-effect\n  transistors with the graphene channel and the black-As$_x$P$_{1-x}$ gate\n  layer: We propose the terahertz (THz) detectors based on field-effect transistors\n(FETs) with the graphene channel (GC) and the black-Arsenic (b-As)\nblack-Phosphorus (b-P), or black-Arsenic-Phosphorus (b-As$_x$P$_{1-x}$) gate\nbarrier layer. The operation of the GC-FET detectors is associated with the\ncarrier heating in the GC by the THz electric field resonantly excited by\nincoming radiation leading to an increase in the rectified current between the\nchannel and the gate over the b-As$_x$P$_{1-x}$ energy barrier layer (BLs). The\nspecific feature of the GC-FETs under consideration is relatively low energy\nBLs and the possibility to optimize the device characteristics by choosing the\nbarriers containing a necessary number of the b-As$_x$P$_{1-x}$ atomic layers\nand a proper gate voltage. The excitation of the plasma oscillations in the\nGC-FETs leads to the resonant reinforcement of the carrier heating and the\nenhancement of the detector responsivity. The room temperature responsivity can\nexceed the values of $10^3$~A/W. The speed of the GC-FET detector's response to\nthe modulated THz radiation is determined by the processes of carrier heating.\nAs shown, the modulation frequency can be in the range of several GHz at room\ntemperatures."
    },
    {
        "anchor": "Theory on the Ultrafast Manipulation of Electron Spin by Optical Means: Based on a multi-particle-state stimulated Raman adiabatic passage approach,\na comprehensive theoretical study on the ultrafast optical manipulation of\nelectron spins in quantum wells is presented. In addition to corroborating the\nexperimental findings [Science {\\bf 292}, 2458 (2001)], we improve the\nexpression of the optical-pulse-induced effective magnetic field, in comparison\nwith the one obtained via the conventional single-particle ac-Stark shift.\nFurther study of the effect of hole spin relaxation reveals that while the\ncoherent optical manipulation of electron spin in undoped quantum wells would\ndeteriorate in the presence of relatively fast hole-spin relaxation, the\ncoherent control in doped systems can be quite robust against the decoherence.\nThe implications of present results on quantum dots will also be discussed.",
        "positive": "Conductance of disordered graphene superlattice: We study the conductance of disordered graphene superlattices with\nshort-range structural correlations. The system consists of electron- and\nhole-doped graphenes of various thicknesses, which fluctuate randomly around\ntheir mean value. The effect of the randomness on the probability of\ntransmission through the system of various sizes is studied. We show that in a\ndisordered superlattice the quasiparticle that approaches the barrier interface\nalmost perpendicularly transmits through the system. The conductivity of the\nfinite-size system is computed and shown that the conductance vanishes when the\nsample size becomes very large, whereas for some specific structures the\nconductance tends to a nonzero value in the thermodynamics limit."
    },
    {
        "anchor": "Carrier transport theory for twisted bilayer graphene in the metallic\n  regime: Understanding the normal-metal state transport in twisted bilayer graphene\nnear magic angle is of fundamental importance as it provides insights into the\nmechanisms responsible for the observed strongly correlated insulating and\nsuperconducting phases. Here we provide a rigorous theory for phonon-dominated\ntransport in twisted bilayer graphene describing its unusual signatures in the\nresistivity (including the variation with electron density, temperature, and\ntwist angle) showing good quantitative agreement with recent experiments. We\ncontrast this with the alternative Planckian dissipation mechanism that we show\nis incompatible with available experimental data. An accurate treatment of the\nelectron-phonon scattering requires us to go well beyond the usual treatment,\nincluding both interband and intraband processes, considering the\nfinite-temperature dynamical screening of the electron-phonon matrix element,\nand going beyond the linear Dirac dispersion. In addition to explaining the\nobservations in currently available experimental data, we make concrete\npredictions that can be tested in ongoing experiments.",
        "positive": "Paired and clustered quantum Hall states: We briefly summarize properties of quantum Hall states with a pairing or\nclustering property. Their study employs a fundamental connection with\nparafermionic Conformal Field Theories. We report on closed form expressions\nfor the many-body wave functions and on multiplicities of the fundamental\nquasi-hole excitations."
    },
    {
        "anchor": "Superradiant Decay of Cyclotron Resonance of Two-Dimensional Electron\n  Gases: We report on the observation of collective radiative decay, or superradiance,\nof cyclotron resonance (CR) in high-mobility two-dimensional electron gases in\nGaAs quantum wells using time-domain terahertz magnetospectroscopy. The decay\nrate of coherent CR oscillations increases linearly with the electron density\nin a wide range, which is a hallmark of superradiant damping. Our fully quantum\nmechanical theory provides a universal formula for the decay rate, which\nreproduces our experimental data without any adjustable parameter. These\nresults firmly establish the many-body nature of CR decoherence in this system,\ndespite the fact that the CR frequency is immune to electron-electron\ninteractions due to Kohn's theorem.",
        "positive": "Cyclotron resonance of the magnetic ratchet effect and second harmonic\n  generation in bilayer graphene: We model the magnetic ratchet effect in bilayer graphene in which a dc\nelectric current is produced by an ac electric field of frequency $\\omega$ in\nthe presence of a steady in-plane magnetic field and inversion-symmetry\nbreaking. In bilayer graphene, the ratchet effect is tunable by an external\nmetallic gate which breaks inversion symmetry. For zero in-plane magnetic\nfield, we show that trigonal warping and inversion-symmetry breaking are able\nto produce a large dc valley current, but not a non-zero total dc charge\ncurrent. For the magnetic ratchet in a tilted magnetic field, the perpendicular\nfield component induces cyclotron motion with frequency $\\omega_c$ and we find\nthat the dc current displays cyclotron resonance at $\\omega_c = \\omega$,\nalthough this peak in the current is actually smaller than its value at\n$\\omega_c = 0$. Second harmonic generation, however, is greatly enhanced by\nresonances at $\\omega_c = \\omega$ and $\\omega_c = 2\\omega$ for which the\ncurrent is generally much larger than at $\\omega_c = 0$."
    },
    {
        "anchor": "Peierls substitution in the energy dispersion of a hexagonal lattice: The method of the Peierls substitution in studying the magnetic subband\nstructure of a hexagonal lattice is re-examined. Several errors in the\nformalism of a couple of recent papers are pointed out and rectified so as to\ndescribe the effect of the magnetic field pertinently.",
        "positive": "Time-dependent evolution of two coupled Luttinger liquids: We consider two disconnected Luttinger liquids which are coupled at $t=0$\nthrough chiral density-density interactions. Both for $t<0$ and $t \\geq 0$ the\nsystem is exactly solvable by means of bosonization and this allows to evaluate\nanalytically the time-dependence of correlation functions. We find that in the\nlong-time limit the critical exponent governing the one-particle correlation\nfunction differs from the exponent dictated by the equilibrium ground state of\nthe coupled system. We also discuss how this reflects on some physical\nquantities which are accessible in real experiments."
    },
    {
        "anchor": "Microscopic derivation of Spin-transfer torques in ferromagnets: Spin-transfer torque (STT) provides key mechanisms for current-induced\nphenomena in ferromagnets. While it is widely accepted that STT involves both\nadiabatic and non-adiabatic contributions, their underlying physics and range\nof validity are quite controversial. By computing microscopically the response\nof conduction electron spins to a time varying and spatially inhomogeneous\nmagnetic background, we derive the adiabatic and non-adiabatic STT in a unified\nfashion. Our result confirms the macroscopic theory [Phys. Rev. Lett.\n\\textbf{93},~127204 (2004)] with all coefficients matched exactly. Our\nderivation also reveals a benchmark on the validity of the result, which is\nused to explain three recent measurements of the non-adiabatic STT in quite\ndifferent settings.",
        "positive": "X-Ray Microscopy of Spin Wave Focusing using a Fresnel Zone Plate: Magnonics, i.e. the artificial manipulation of spin waves, is a flourishing\nfield of research with many potential uses in data processing within reach.\nApart from the technological applications the possibility to directly influence\nand observe these types of waves is of great interest for fundamental research.\nGuidance and steering of spin waves has been previously shown and lateral spin\nwave confinement has been achieved. However, true spin wave focusing with both\nlateral confinement and increase in amplitude has not been shown before. Here,\nwe show for the first time spin wave focusing by realizing a Fresnel zone plate\ntype lens. Using x-ray microscopy we are able to directly image the propagation\nof spin waves into the nanometer sized focal spot. Furthermore, we observe that\nthe focal spot can be freely moved in a large area by small variations of the\nbias field. Thus, this type of lens provides a steerable intense nanometer\nsized spin wave source. Potentially, this could be used to selectively\nilluminate magnonic devices like nano oscillators with a steerable spin wave\nbeam."
    },
    {
        "anchor": "Influence of magnetic surface anisotropy on spin wave reflection from\n  the edge of ferromagnetic film: We study propagation of the Gaussian beam of spin waves and its reflection\nfrom the edge of thin yttrium-iron-garnet film with in-plane magnetization\nperpendicular to this edge. We have performed micromagnetic simulations\nsupported by analytical calculations to investigate influence of the surface\nmagnetic anisotropy present at the film edge on the reflection, especially in\nthe context of the Goos-Hanchen effect. We have shown the appearance of a\nnegative lateral shift between reflected and incident spin wave beams' spots.\nThis shift is particularly sensitive to the surface magnetic anisotropy value\nand is a result of the Goos-Hanchen shift which is sensitive to the magnitude\nof the anisotropy and of the bending of spin wave beam. We have demonstrated\nthat the demagnetizing field provide graded increase of the refractive index\nfor spin waves, which is responsible for the bending.",
        "positive": "Inelastic scattering and cooling of photoexcited electrons through\n  coupling with acoustic, optic and surface polar optic phonons in graphene: The acoustic, optic, and surface polar optic phonons are the three important\nintrinsic and extrinsic phononic modes that increasingly populate graphene on a\nsubstrate with rising temperatures; the coupling of which with photoexcited hot\ncarriers in the equipartition regime provides significant pathways for\nelectron-phonon relaxation. In this paper, we theoretically investigate the\nrelative significance of the three phononic modes in electron scattering and\ncooling phenomena in single layer graphene, including their comparison with\nsupercollision driven power loss, and obtain analytical formulae on the energy\ndependence of electron-phonon scattering rate and cooling power in the\nBoltzmann transport formalism. The obtained analytical solutions not only\nclosely reproduce the results for scattering rate and cooling power, as that\nobtained from the earlier reported numerically tractable integral forms, but\nalso enable us to derive closed-form formulae of the cooling time and thermal\nconductance. The important role of Pauli blocking that prevents transition to\nfilled energy states has also been elucidated in the estimation of the\nscattering rate and cooling power density for all the three modes. The obtained\nformulae provide a better insight into the dynamics of hot electron phenomena\ngiving an explicit view on the interplay of the different variables that affect\nthe transport quantities under investigation. The formulae can also be\npotentially useful for performance optimization of transport quantities in\nnumerical optimization methods since the first and second-order derivatives are\neasily deducible from these formulae."
    },
    {
        "anchor": "Twists in Ferromagnetic Monolayers With Trigonal Prismatic Symmetry: Two-dimensional materials such as graphene or hexagonal boron nitride are\nindispensable in industry. The recently discovered 2D ferromagnetic materials\nalso promise to be vital for applications. In this work, we develop a\nphenomenological description of non-centrosymmetric 2D ferromagnets with\ntrigonal prismatic crystal structure. We chose to study this special symmetry\ngroup since these materials do break inversion symmetry and therefore, in\nprinciple, allow for chiral spin structures such as magnetic helices and\nskyrmions. However, unlike all non-centrosymmetric magnets known so far, we\nshow that the symmetry of magnetic trigonal prismatic monolayers neither allow\nfor an internal relativistic Dzyaloshinskii-Moriya interaction (DMI) nor a\nreactive spin-orbit torque. We demonstrate that the DMI only becomes important\nat the boundaries, where it modifies the boundary conditions of the\nmagnetization and leads to a helical equilibrium state with a helical\nwavevector that is inherently linked to the internal spin orientation.\nFurthermore, we find that the helical wavevector can be electrically\nmanipulated via dissipative spin-torque mechanisms. Our results reveal that 2D\nmagnets offer a large potential for unexplored magnetic effects.",
        "positive": "Molecular Wires Acting as Coherent Quantum Ratchets: The effect of laser fields on the electron transport through a molecular wire\nbeing weakly coupled to two leads is investigated. The molecular wire acts as a\ncoherent quantum ratchet if the molecule is composed of periodically arranged,\nasymmetric chemical groups. This setup presents a quantum rectifier with a\nfinite dc-response in the absence of a static bias. The nonlinear current is\nevaluated in closed form within the Floquet basis of the isolated, driven wire.\nThe current response reveals multiple current reversals together with a\nnonlinear dependence (reflecting avoided quasi-energy crossings) on both, the\namplitude and the frequency of the laser field. The current saturates for long\nwires at a nonzero value, while it may change sign upon decreasing its length."
    },
    {
        "anchor": "Heterostrain rules the flat-bands in magic-angle twisted graphene layers: The moir\\'e of twisted graphene bilayers can generate flat bands in which\ncharge carriers do not posses enough kinetic energy to escape Coulomb\ninteractions with each other leading to the formation of novel strongly\ncorrelated electronic states. This exceptionally rich physics relies on the\nprecise arrangement between the layers.We survey published Scanning Tunnelling\nMicroscope (STM) measurements to prove that near the magic angle, native\nheterostrain, the relative deformations between the layers, dominates twist in\ndetermining the flat bands. This is demonstrated at large doping where\nelectronic correlations have a weak effect and where we also show that\ntip-induced strain can have a strong influence. In the opposite situation of\nlow doping, we find that electronic correlation further normalize the flat\nbands in a way that strongly depends on experimental details.",
        "positive": "Plasmons in a Square of Two-Dimensional Electrons: Microwave absorption spectra of a single square of two-dimensional electrons\n(2DES) have been investigated using an optical detection technique. Fundamental\ndipole and harmonic quadrupole plasmon modes have been identified and compared\nto those in the disk geometry. In the square-shaped 2DES, a strong interaction\nis discovered between the neighboring plasmon modes, whereas no such\nhybridization is observed in the disk-shaped geometry. We establish a rigid\ntheoretical platform to analytically describe the magneto-optical response of\nconfined two-dimensional systems. The developed theory provides a proper\ndescription of the obtained experimental results."
    },
    {
        "anchor": "Current carrying Andreev bound states in a Superconductor-Ferromagnet\n  proximity system: We study the ground state properties of a ferromagnet-superconductor\nheterostructure on the basis of a quasiclassical theory. We have solved the\nEilenberger equations together with Maxwell's equation fully self-consistently\nand found that due to the proximity effect a Fulde-Ferrel-Larkin-Ovchinnikov\n(FFLO) like state is realized in such system. Moreover this state has\noscillations of the pairing amplitude in either one or two directions,\ndepending on the exchange splitting and thickness of the ferromagnet. In\nparticular, using semiclassical arguments (Bohr-Sommerfeld quantization rule)\nwe show that owing to the presence of the Andreev bound states in the\nferromagnet, a spontaneous current in the ground state is generated as a\nhallmark of the FFLO state in the direction parallel to the interface. We also\ndiscuss the effects of the the elastic disorder and finite transparency of the\ninterface on the properties of the $FFLO$ state in the system.",
        "positive": "General conditions for proximity-induced odd-frequency superconductivity\n  in two-dimensional electronic systems: We obtain the general conditions for the emergence of odd-frequency\nsuperconducting pairing in a two-dimensional (2D) electronic system\nproximity-coupled to a superconductor, making minimal assumptions about both\nthe 2D system and the superconductor. Using our general results we show that a\nsimple heterostructure formed by a monolayer of a group VI transition metal\ndichalcogenide, such as molybdenum disulfide, and an s-wave superconductor with\nRashba spin-orbit coupling will exhibit odd-frequency superconducting pairing.\nFurthermore, we show that in such a heterostructure the odd-frequency pairing\namplitude will be proportional to the product of the Rashba spin-orbit coupling\nin the substrate and the spin-orbit coupling in the dichalcogenide layer."
    },
    {
        "anchor": "Non-local magnon transport in the compensated ferrimagnet GdIG: We study the diffusive transport of magnons through the compensated\nferrimagnetic insulator Gd3Fe5O12 (GdIG). The magnons are injected and detected\nelectrically in a non-local measurement configuration via two parallel Pt\nstrips deposited on top of the ferrimagnet. GdIG exhibits a rich magnon\nspectrum, with several thermally populated magnon bands at room temperature. We\nobserve a strong temperature and field dependence of the non-local voltage in\nthe detector strip. Just below the magnetization compensation temperature we\nfind that the increasing magnetic field causes an unexpected enhancement of the\nnon-local signal. A comparison with GdIG spin wave spectra obtained from\natomistic modeling indicates that the thermal magnon population is important\nfor understanding the non-local voltage signal.",
        "positive": "Kondo Resonance of a Microwave Photon: We emulate renormalization group models, such as the Spin-Boson Hamiltonian\nor the anisotropic Kondo model, from a quantum optics perspective by\nconsidering a superconducting device. The infra-red confinement involves photon\nexcitations of two tunable transmission lines entangled to an artificial\nspin-1/2 particle or double-island charge qubit. Focusing on the propagation of\nmicrowave light, in the underdamped regime of the Spin-Boson model, we identify\na many-body resonance where a photon is absorbed at the renormalized qubit\nfrequency and reemitted forward in an elastic manner. We also show that\nasymptotic freedom of microwave light is reached by increasing the input signal\namplitude at low temperatures which allows the disappearance of the\ntransmission peak."
    },
    {
        "anchor": "In-plane magnetic field-driven symmetry breaking in topological\n  insulator-based three-terminal junctions: Topological surface states of three-dimensional topological insulator\nnanoribbons and their distinct magnetoconductance properties are promising for\ntopoelectronic applications and topological quantum computation. A crucial\nbuilding block for nanoribbon-based circuits are three-terminal junctions.\nWhile the transport of topological surface states on a planar boundary is not\ndirectly affected by an in-plane magnetic field, the orbital effect cannot be\nneglected when the surface states are confined to the boundary of a nanoribbon\ngeometry. Here, we report on the magnetotransport properties of such\nthree-terminal junctions. We observe a dependence of the current on the\nin-plane magnetic field, with a distinct steering pattern of the surface state\ncurrent towards a preferred output terminal for different magnetic field\norientations. We demonstrate that this steering effect originates from the\norbital effect, trapping the phase-coherent surface states in the different\nlegs of the junction on opposite sides of the nanoribbon and breaking the\nleft-right symmetry of the transmission across the junction. The reported\nmagnetotransport properties demonstrate that an in-plane magnetic field is not\nonly relevant but also very useful for the characterization and manipulation of\ntransport in three-dimensional topological insulator nanoribbon-based junctions\nand circuits, acting as a topoelectric current switch.",
        "positive": "Electric-field control of interfering transport pathways in a\n  single-molecule anthraquinone transistor: It is understood that molecular conjugation plays an important role in charge\ntransport through single-molecule junctions. Here, we investigate electron\ntransport through an anthraquinone based single-molecule three-terminal device.\nWith the use of an electric-field induced by a gate electrode, the molecule is\nreduced resulting into a ten-fold increase in the off-resonant differential\nconductance. Theoretical calculations link the change in differential\nconductance to a reduction-induced change in conjugation, thereby lifting\ndestructive interference of transport pathways."
    },
    {
        "anchor": "Floquet vortex states induced by light carrying the orbital angular\n  momentum: We propose a scheme to create an electronic Floquet vortex state by\nirradiating a two-dimensional semiconductor with the laser light carrying\nnon-zero orbital angular momentum. We analytically and numerically study the\nproperties of the Floquet vortex states, with the methods analogous to the ones\npreviously applied to the analysis of superconducting vortex states. We show\nthat such Floquet vortex states are similar to the superconducting vortex\nstates, and they exhibit a wide range of tunability. To illustrate the\npotential utility of such tunability, we show how such states could be used for\nquantum state engineering.",
        "positive": "Role of Charge Traps in the Performance of Atomically-Thin Transistors: Transient currents in atomically thin MoTe$_2$ field-effect transistor are\nmeasured during cycles of pulses through the gate electrode. The transients are\nanalyzed in light of a newly proposed model for charge trapping dynamics that\nrenders a time-dependent change in threshold voltage the dominant effect on the\nchannel hysteretic behavior over emission currents from the charge traps. The\nproposed model is expected to be instrumental in understanding the fundamental\nphysics that governs the performance of atomically thin FETs and is applicable\nto the entire class of atomically thin-based devices. Hence, the model is vital\nto the intelligent design of fast and highly efficient opto-electronic devices."
    },
    {
        "anchor": "Strain-assisted magnetization reversal in Co/Ni multilayers with\n  perpendicular magnetic anisotropy: Multifunctional materials composed of ultrathin magnetic films with\nperpendicular magnetic anisotropy combined with ferroelectric substrates\nrepresent a new approach toward low power, fast, high density spintronics. Here\nwe demonstrate Co/Ni multilayered films with tunable saturation magnetization\nand perpendicular anisotropy grown directly on ferroelectric PZT\n[Pb(Zr_xTi_1-x)O_3] substrate plates. Electric fields up to +/- 2 MV/m expand\nthe PZT by 0.1% and generate at least 0.02% in-plane compression in the Co/Ni\nmultilayered film. Modifying the strain with a voltage can reduce the coercive\nfield by over 30%. We also demonstrate that alternating in-plane tensile and\ncompressive strains (less than 0.01%) can be used to propagate magnetic domain\nwalls. This ability to manipulate high anisotropy magnetic thin films could\nprove useful for lowering the switching energy for magnetic elements in future\nvoltage-controlled spintronic devices.",
        "positive": "Transverse \"resistance overshoot\" in a Si/SiGe two-dimensional electron\n  gas in the quantum Hall effect regime: We investigate the peculiarities of the \"overshoot\" phenomena in the\ntransverse Hall resistance R_{xy} in Si/SiGe. Near the low magnetic field end\nof the quantum Hall effect plateaus, when the filling factor \\nu approaches an\ninteger i, R_{xy} overshoots the normal plateau value h/ie^2. However, if\nmagnetic field B increases further, R_{xy} decreases to its normal value. It is\nshown that in the investigated sample n-Si/Si_{0.7}Ge_{0.3}, overshoots exist\nfor almost all \\nu. Existence of overshoot in R_{xy} observed in different\nmaterials and for different \\nu, where splitting of the adjacent Landau bands\nhas different character, hints at the common origin of this effect. Comparison\nof the experimental curves R_{xy}(\\nu) for \\nu = 3 and \\nu = 5 with and without\novershoot showed that this effect exist in the whole interval between plateaus,\nnot only in the region where R_{xy} exceeds the normal plateau value."
    },
    {
        "anchor": "Zero-energy modes in super-chiral nanographene networks of\n  phenalenyl-tessellation molecules: We have derived a general rule for the appearance of zero-energy modes in\nsuper-chiral defective nanographene. This so-called \"super-zero-sum rule\"\ndefines the appearance of zero modes in a new class of materials, which we call\npolymerized phenalenyl-tessellation molecules (poly-PTMs). Through theoretical\nmodeling of the electronic states in these molecular forms, we provide concrete\nsolutions for achieving the quantum-spin systems needed in quantum-information\ndevices. The two-dimensional graph of electronic $\\pi$-orbitals in the poly-PTM\npossesses a number of localized zero modes equivalent to that of vacancies in\nPTMs. In addition to the modes confined to each PTM, another type of zero mode\nmay appear according to the super-zero-sum rule supported by super-chirality.\nSince the magnetic interactions among quantum spins in the zero modes are\ndetermined by how they appear (which is governed by the super-zero-sum rule),\nour rule is indispensable for designing quantum-information devices using\nelectron zero modes in poly-aromatic hydrocarbons and defective graphene with\nvacancies.",
        "positive": "Chirality-controlled spin scattering through quantum interference: Chirality-induced spin selectivity has been reported in many experiments, but\na generally accepted theoretical explanation has not yet been proposed. Here,\nwe introduce a simple model system of a straight cylindrical free-electron\nwire, containing a helical string of atomic scattering centers, with spin-orbit\ninteraction. The advantage of this simple model is that it allows deriving\nanalytical expressions for the spin scattering rates, such that the origin of\nthe effect can be easily followed. We find that spin-selective scattering can\nbe viewed as resulting from constructive interference of partial waves\nscattered by the spin-orbit terms. We demonstrate that forward scattering rates\nare independent of spin, while back scattering is spin dependent over wide\nwindows of energy. Although the model does not represent the full details of\nelectron transmission through chiral molecules, it clearly reveals a mechanism\nthat could operate in chiral systems."
    },
    {
        "anchor": "Observation of quantum jumps in a superconducting artificial atom: A continuously monitored quantum system prepared in an excited state will\ndecay to its ground state with an abrupt jump. The jump occurs stochastically\non a characteristic time scale T1, the lifetime of the excited state. These\nquantum jumps, originally envisioned by Bohr, have been observed in trapped\natoms and ions, single molecules, photons, and single electrons in cyclotrons.\nHere we report the first observation of quantum jumps in a macroscopic quantum\nsystem, in our case a superconducting \"artificial atom\" or quantum bit (qubit)\ncoupled to a superconducting microwave cavity. We use a fast, ultralow-noise\nparametric amplifier to amplify the microwave photons used to probe the qubit\nstate, enabling continuous high-fidelity monitoring of the qubit. This\ntechnique represents a major step forward for solid state quantum information\nprocessing, potentially enabling quantum error correction and feedback, which\nare essential for building a quantum computer. Our technology can also be\nreadily integrated into hybrid circuits involving molecular magnets, nitrogen\nvacancies in diamond, or semiconductor quantum dots.",
        "positive": "Reconstructing the potential configuration in a high-mobility\n  semiconductor heterostructure with scanning gate microscopy: The weak disorder potential seen by the electrons of a two-dimensional\nelectron gas in high-mobility semiconductor heterostructures leads to\nfluctuations in the physical properties and can be an issue for nanodevices. In\nthis paper, we show that a scanning gate microscopy (SGM) image contains\ninformation about the disorder potential, and that a machine learning approach\nbased on SGM data can be used to determine the disorder. We reconstruct the\nelectric potential of a sample from its experimental SGM data and validate the\nresult through an estimate of its accuracy."
    },
    {
        "anchor": "Revealing tensor monopoles through quantum-metric measurements: Monopoles are intriguing topological objects, which play a central role in\ngauge theories and topological states of matter. While conventional monopoles\nare found in odd-dimensional flat spaces, such as the Dirac monopole in three\ndimensions and the non-Abelian Yang monopole in five dimensions, more exotic\nobjects were predicted to exist in even dimensions. This is the case of \"tensor\nmonopoles\", which are associated with generalized (tensor) gauge fields, and\nwhich can be defined in four dimensional flat spaces. In this work, we\ninvestigate the possibility of creating and measuring such a tensor monopole,\nby introducing a realistic three-band model defined over a four-dimensional\nparameter space. Our probing method is based on the observation that the\ntopological charge of this tensor monopole, which we relate to a generalized\nBerry curvature, can be directly extracted from the quantum metric. We propose\na realistic three-level atomic system, where tensor monopoles could be\ngenerated and revealed through quantum-metric measurements.",
        "positive": "2D MoS2-Graphene-based multilayer van der Waals heterostructures:\n  Enhanced charge transfer and optical absorption, and electric-field tunable\n  Dirac point and band gap: Multilayer van der Waals (vdWs) heterostructures assembled by diverse\natomically thin layers have demonstrated a wide range of fascinating phenomena\nand novel applications. Understanding the interlayer coupling and its\ncorrelation effect is paramount for designing novel vdWs heterostructures with\ndesirable physical properties. Using a detailed theoretical study of 2D\nMoS2-graphene (GR)-based heterostructures based on state-of-the-art hybrid\ndensity functional theory, we reveal that for 2D few-layer heterostructures,\nvdWs forces between neighboring layers depend on the number of layers. Compared\nto that in bilayer, the interlayer coupling in trilayer vdW heterostructures\ncan significantly be enhanced by stacking the third layer, directly supported\nby short interlayer separations and more interfacial charge transfer. The\ntrilayer shows strong light absorption over a wide range (<700 nm), making it\nvery potential for solar energy harvesting and conversion. Moreover, the Dirac\npoint of GR and band gaps of each layer and trilayer can be readily tuned by\nexternal electric field, verifying multilayer vdWs heterostructures with unqiue\noptoelectronic properties found by experiments. These results suggest that\ntuning the vdWs interaction, as a new design parameter, would be an effective\nstrategy for devising particular 2D multilayer vdWs heterostructures to meet\nthe demands in various applications."
    },
    {
        "anchor": "Electrical Control of 2D Magnetism in Bilayer CrI3: The challenge of controlling magnetism using electric fields raises\nfundamental questions and addresses technological needs such as low-dissipation\nmagnetic memory. The recently reported two-dimensional (2D) magnets provide a\nnew system for studying this problem owing to their unique magnetic properties.\nFor instance, bilayer chromium triiodide (CrI3) behaves as a layered\nantiferromagnet with a magnetic field-driven metamagnetic transition. Here, we\ndemonstrate electrostatic gate control of magnetism in CrI3 bilayers, probed by\nmagneto-optical Kerr effect (MOKE) microscopy. At fixed magnetic fields near\nthe metamagnetic transition, we realize voltage-controlled switching between\nantiferromagnetic and ferromagnetic states. At zero magnetic field, we\ndemonstrate a time-reversal pair of layered antiferromagnetic states which\nexhibit spin-layer locking, leading to a remarkable linear dependence of their\nMOKE signals on gate voltage with opposite slopes. Our results pave the way for\nexploring new magnetoelectric phenomena and van der Waals spintronics based on\n2D materials.",
        "positive": "Enhanced asymmetric valley scattering by scalar fields in non-uniform\n  out-of-plane deformations in graphene: We study the electron scattering produced by local out-of-plane strain\ndeformations in the form of Gaussian bumps in graphene. Of special interest is\nto take into account the scalar field associated with the redistribution of\ncharge due to deformations, and in the same footing as the pseudomagnetic\nfield. Working with the Born approximation approach we show analytically that\neven when a relatively small scalar field is considered, a rather strong valley\nasymmetric scattering could arise as a function of the energy and angle of\nincidence. In addition, we find that the valley polarization can reverse its\nsign as the incident energy is increased. These behaviors are totally absent if\nthe scalar field is neglected. These results are supported by quantum dynamical\nsimulations of electron wave packets. Results for the average trajectories of\nwave packets in locally strained graphene clearly show focusing and beam\nsplitting effects enhanced by the presence of the scalar field that can be of\ninterest in the implementation of valleytronic devices."
    },
    {
        "anchor": "Lossless Spin-Orbit Torque in Antiferromagnetic Topological Insulator\n  MnBi$_2$Te$_4$: We formulate and quantify the spin-orbit torque (SOT) in intrinsic\nantiferromagnetic topological insulator $\\rm MnBi_2Te_4$ of a few\nseptuple-layer thick, which exhibits conspicuous layer-resolved\ncharacteristics. Contrary to known current-induced torques, the SOT in\ninsulating $\\rm MnBi_2Te_4$ is driven by an electric field (or voltage). We\nfurther study the SOT-induced magnetic resonances, where in the\ntri-septuple-layer case we identify a peculiar exchange mode that is blind to\nmicrowaves but can be exclusively driven by the predicted SOT. As an inverse\neffect of the SOT, topological charge pumping generates an adiabatic current\ndevoid of Joule heating, which occurs concomitantly with the SOT and gives rise\nto an overall magneto-reactance for $\\rm MnBi_2Te_4$, enabling a lossless\nconversion of electric power into magnetic dynamics.",
        "positive": "Anomalous friction in suspended graphene: Since the discovery of the Amonton's law and with support of modern\ntribological models, friction between surfaces of three-dimensional materials\nis known to generally increase when the surfaces are in closer contact. Here,\nusing molecular dynamics simulations of friction force microscopy on suspended\ngraphene, we demonstrate an increase of friction when the scanning tip is\nretracted away from the sample. We explain the observed behavior and address\nwhy this phenomenon has not been observed for isotropic 3-D materials."
    },
    {
        "anchor": "Kinetic models of Quantum Size Effect-directed nanocluster self-assembly\n  in atomic corrals: Two simple kinetic models of Quantum Size Effect-directed nanocluster\nself-assembly in circular atomic corrals are discussed. The models correspond\nto an adsorption (either a physisorption or a chemisorption) and an\nadsorption-diffusion regimes that are typical at low and high temperatures,\nrespectively. Small magnitudes of a variation of the electronic local density\nof states is shown to be the prime factor that impedes self-assembly in the\nlatter regime.",
        "positive": "Duality and the Modular Group in the Quantum Hall Effect: We explore the consequences of introducing a complex conductivity into the\nquantum Hall effect. This leads naturally to an action of the modular group on\nthe upper-half complex conductivity plane. Assuming that the action of a\ncertain subgroup, compatible with the law of corresponding states, commutes\nwith the renormalisation group flow, we derive many properties of both the\ninteger and fractional quantum Hall effects, including: universality; the\nselection rule $|p_1q_2 - p_2q_1|=1$ for quantum Hall transitions between\nfilling factors $\\nu_1=p_1/q_1$ and $\\nu_2=p_2/q_2$; critical values for the\nconductivity tensor; and Farey sequences of transitions. Extra assumptions\nabout the form of the renormalisation group flow lead to the semi-circle rule\nfor transitions between Hall plateaus."
    },
    {
        "anchor": "Emergence of large spin-charge interconversion at an oxidized Cu/W\n  interface: Spin-orbitronic devices can integrate memory and logic by exploiting\nspin-charge interconversion (SCI), which is optimized by design and materials\nselection. In these devices, such as the magnetoelectric spin-orbit (MESO)\nlogic, interfaces are crucial elements as they can prohibit or promote spin\nflow in a device as well as possess spin-orbit coupling resulting in\ninterfacial SCI. Here, we study the origin of SCI in a Py/Cu/W lateral spin\nvalve and quantify its efficiency. An exhaustive characterization of the\ninterface between Cu and W electrodes uncovers the presence of an oxidized\nlayer (WO$_x$). We determine that the SCI occurs at the Cu/WO$_x$ interface\nwith a temperature-independent interfacial spin-loss conductance of $G_{||}\n\\approx$ 20 $\\times$ 10$^{13} \\Omega^{-1}m^{-2}$ and an interfacial spin-charge\nconductivity $\\sigma_{SC}=-$1610 $\\Omega^{-1}cm^{-1}$ at 10 K ($-$830\n$\\Omega^{-1}cm^{-1}$ at 300 K). This corresponds to an efficiency given by the\ninverse Edelstein length $\\lambda_{IEE}=-$0.76 nm at 10 K ($-$0.4 nm at 300 K),\nwhich is remarkably larger than in metal/metal and metal/oxide interfaces and\nbulk heavy metals. The large SCI efficiency at such an oxidized interface is a\npromising candidate for the magnetic readout in MESO logic devices.",
        "positive": "Spin transfer torque induced paramagnetic resonance: We show how the spin-transfer torque generated by an ac voltage may be used\nto excite a paramagnetic resonance of an atomic spin deposited on a metallic\nsurface. This mechanism is independent of the environment of the atom and may\nexplain the ubiquity of the paramagnetic resonance reported by Baumann\n$\\textit{et al.}$ [$\\href{http://dx.doi.org/10.1126/science.aac8703}{Science\n\\textbf{350}, 417 (2015)}$]. The current and spin dynamics are modeled by a\ntime-dependent Redfield master equation generalized to account for the periodic\ndriven voltage. Our approach shows that the resonance effect is a consequence\nof the nonlinearity of the coupling between the magnetic moment and the\nspin-polarized current which generates a large second-harmonic amplitude that\ncan be measured in the current signal."
    },
    {
        "anchor": "Stacking transition in bilayer graphene caused by thermally activated\n  rotation: Crystallographic alignment between two-dimensional crystals in van der Waals\nheterostructures brought a number of profound physical phenomena, including\nobservation of Hofstadter butterfly and topological currents, and promising\nnovel applications, such as resonant tunnelling transistors. Here, by probing\nthe electronic density of states in graphene using graphene-hexagonal boron\nnitride tunnelling transistors, we demonstrate a structural transition of\nbilayer graphene from incommensurate twisted stacking state into a commensurate\nAB stacking due to a macroscopic graphene self-rotation. This structural\ntransition is accompanied by a topological transition in the reciprocal space\nand by pseudospin texturing. The stacking transition is driven by van der Waals\ninteraction energy of the two graphene layers and is thermally activated by\nunpinning the microscopic chemical adsorbents which are then removed by the\nself-cleaning of graphene.",
        "positive": "Three-Dirac-fermion approach to unexpected universal gapless surface\n  states of van der Waals magnetic topological insulators: Layered van der Waals (vdW) topological materials, especially the recently\ndiscovered MnBi$_2$Te$_4$-family magnetic topological insulators (TIs), have\naroused great attention. However, there has been a serious debate about whether\nthe surface states are gapped or gapless for antiferromagnetic (AFM) TI\nMnBi$_2$Te$_4$, which is crucial to the prospect of various magnetic\ntopological phenomena. Here, a minimal three-Dirac-fermion approach is\ndeveloped to generally describe topological surface states of\nnonmagnetic/magnetic vdW TIs under the modulation of the interlayer vdW gap. In\nparticular, this approach is applied to address the controversial issues\nconcerning the surface states of vdW AFM TIs. Remarkably, topologically\nprotected gapless Dirac-cone surface states are found to arise due to a small\nexpansion of the interlayer vdW gap on the surface, when the Chern number\nequals zero for the surface ferromagnetic layer; while the surface states\nremain gapped in all other cases. These results are further confirmed by our\nfirst-principles calculations on AFM TI MnBi$_2$Te$_4$. The theorectically\ndiscovered gapless Dirac-cone states provide a unique mechanism for\nunderstanding the puzzle of the experimentally observed gapless surface states\nin MnBi$_2$Te$_4$. This work also provides a promising way for experiments to\nrealize the intrinsic magnetic quantum anomalous Hall effect in MnBi$_2$Te$_4$\nfilms with a large energy gap."
    },
    {
        "anchor": "Single-shot time-domain studies of spin-torque-driven switching in\n  magnetic tunnel junctions: We report single-shot measurements of resistance versus time for thermally\nassisted spin-torque-driven switching in magnetic tunnel junctions. We achieve\nsufficient sensitivity to resolve the resistance signals leading up to\nswitching, including the variations between individual switching events.\nAnalyses of pre-switching thermal fluctuations allow detailed measurements of\ncoherence times and variations in magnetization precession amplitude. We find\nthat with a small in-plane hard-axis magnetic field the magnetization dynamics\nare more spatially coherent than for the case of zero field.",
        "positive": "Landau-Zener-St\u00fcckelberg Interference of Microwave Dressed States of\n  a Superconducting Phase Qubit: We present the first observation of Landau-Zener-St\\\"{u}ckelberg (LZS)\ninterference of the dressed states arising from an artificial atom, a\nsuperconducting phase qubit, interacting with a microwave field. The dependence\nof LZS interference fringes on various external parameters and the initial\nstate of the qubit agrees quantitatively very well with the theoretical\nprediction. Such LZS interferometry between the dressed states enables us to\ncontrol the quantum states of a tetrapartite solid-state system with ease,\ndemonstrating the feasibility of implementing efficient multipartite quantum\nlogic gates with this unique approach."
    },
    {
        "anchor": "Terahertz Slonczewski propagating spin waves and large output voltage in\n  antiferromagnetic spin-Hall nano-oscillators: We study theoretically antiferromagnet (AFM) based spin-Hall nano-oscillators\n(SHNOs) consisting of a nano-constriction (NC) in a thin-film uniaxial AFM. By\nsolving the derived SW equation we evidence radially propagating spin waves\n(SWs) at THz frequencies similar to the Slonczewski SWs known at GHz\nfrequencies for a ferromagnet-based SHNO. We predict a minimum threshold\ncurrent for a specific NC radius accessible by the state-of-the-art\nnanotechnology. The exchange interaction enhanced spin pumping for AFMs leads\nto a strong thickness dependent threshold frequency. We show that the uniaxial\nAFMs generate ac electrical fields via spin pumping that are three orders of\nmagnitude larger than reported for biaxial AFMs. Our work enhances the\nfundamental understanding of current-driven SWs in AFM-SHNOs and enables\noptimization of practical devices in terms of material choice, device geometry,\nand frequency tunability. The propagating SWs offer remote THz signal\ngeneration and an efficient means for synchronization of SHNOs when aiming at\nhigh power.",
        "positive": "Lanczos-adapted time evolution for open boundary quantum transport: We increase the efficiency of a recently proposed time integration scheme for\ntime dependent quantum transport by using the Lanczos method for time\nevolution. We illustrate our modified scheme in terms of a simple one\ndimensional model. Our results show that the Lanczos-adapted scheme gives a\nlarge increase in numerical efficiency, and is an advantageous route for\nnumerical time integration in ab-initio treatment of open boundary quantum\ntransport phenomena."
    },
    {
        "anchor": "The Existence of Topological Edge States in Honeycomb Plasmonic Lattices: In this paper, we investigate the band properties of 2D honeycomb plasmonic\nlattices consisting of metallic nanoparticles. By means of the coupled dipole\nmethod and quasi-static approximation, we theoretically analyze the band\nstructures stemming from near-field interaction of localized surface plasmon\npolaritons for both the infinite lattice and ribbons. Naturally, the\ninteraction of point dipoles decouples into independent out-of-plane and\nin-plane polarizations. For the out-of-plane modes, both the bulk spectrum and\nthe range of the momentum $k_{\\parallel}$ where edge states exist in ribbons\nare similar to the electronic bands in graphene. Nevertheless, the in-plane\npolarized modes show significant differences, which do not only possess\nadditional non-flat edge states in ribbons, but also have different\ndistributions of the flat edge states in reciprocal space. For in-plane\npolarized modes, we derived the bulk-edge correspondence, namely, the relation\nbetween the number of flat edge states at a fixed $k_\\parallel$, Zak phases of\nthe bulk bands and the winding number associated with the bulk hamiltonian, and\nverified it through four typical ribbon boundaries, i.e. zigzag, bearded\nzigzag, armchair, and bearded armchair. Our approach gives a new topological\nunderstanding of edge states in such plasmonic systems, and may also apply to\nother 2D \"vector wave\" systems.",
        "positive": "Pinning and gyration dynamics of magnetic vortices revealed by\n  correlative Lorentz and bright-field imaging: Topological magnetic textures are of great interest in various scientific and\ntechnological fields. To allow for precise control of nanoscale magnetism, it\nis of great importance to understand the role of intrinsic defects in the host\nmaterial. Here, we use conventional and time-resolved Lorentz microscopy to\nstudy the effect of grain size in polycrystalline permalloy films on the\npinning and gyration orbits of vortex cores inside magnetic nanoislands. To\nassess static pinning, we use in-plane magnetic fields to shift the core across\nthe island while recording its position. This enables us to produce highly\naccurate two-dimensional maps of pinning sites. Based on this technique, we can\ngenerate a quantitative map of the pinning potential for the core, which we\nidentify as being governed by grain boundaries. Furthermore, we investigate the\neffects of pinning on the dynamic behavior of the vortex core using\nstroboscopic Lorentz microscopy, harnessing a new photoemission source that\naccelerates image acquisition by about two orders of magnitude. We find\ncharacteristic changes to the vortex gyration in the form of increased\ndissipation and enhanced bistability in samples with larger grains."
    },
    {
        "anchor": "Resonance Raman mapping as an interface phonon probe in Si-SiO2\n  nanocomposites: Intermediate frequency range (511 - 514 cm-1) Si phonons in Si-SiO2\nnanocomposites are shown to have contribution from both core1 and\nsurface/interface1 Si phonons, where, ratio of contribution of the two depends\non the size of a Si nanocrystal. Further, laser heating experiment shows that\ncontribution of the core phonon increases due to increase in size of a\nnanocrystal. Wavelength dependent Raman mapping reveals that interface phonons\nare observable due to Resonance Raman scattering. This can well be corroborated\nwith the absorption spectra. This understanding can be gainfully used to\nmanipulate and characterize Si-SiO2 nanocomposite, simultaneously for\nphotovoltaic device applications.",
        "positive": "Violation of Fourier's law in homogeneous systems: Hotspot is a ubiquitous phenomenon in microdevices/chips. In homogeneous\nnanoscale graphene disk with a hotspot, a graded thermal conductivity is\nobserved previously even when the system size is fixed. However, the underlying\nphysical mechanism is not clear. In this work, the hotspots in homogeneous 2D\ndisk/3D ball and graphene disk are studied based on phonon Boltzmann transport\nequation. The mechanisms of phonon scattering are analyzed. It is found that\nfor a system with fixed size, the graded thermal conductivity is predictable as\nlong as there is not sufficient phonon scattering, which is independent on\nmaterial properties, dimensions or system size. This work may shed light on\nboth theoretical and experimental studies on heat dissipation of\nmicroelectronics."
    },
    {
        "anchor": "Collective excitations of graphene excitons being in the Bose-Einstein\n  condensate state: Bose-Einstein condensation of the excitons in graphene is considered. We\nsuggested the model spinor equation for neutral particles with short range\ninteraction described the microscopic graphene excitons dynamic. Using this\nequation we derived quantum hydrodynamic equations for description of\ncollective properties of excitons in graphene, particularly for the case when\nexcitons being in the Bose-Einstein condensate (BEC) state. The dispersion of\ncollective excitations in graphene excitons BEC is studied. We shown that\nfrequency of collective excitations is proportional to the square root of the\nwave vector module: $\\omega\\sim \\sqrt{k}$.",
        "positive": "Molecular wire-nanotube interfacial effects on electron transport: We discuss the conductance of a molecular bridge between mesoscopic\nelectrodes supporting low-dimensional transport and bearing an internal\nstructure. As an example for such nanoelectrodes we assume semi-infinite\n(carbon) nanotubes. In the Landauer scattering matrix approach, we show that\nthe conductance of this hybrid is very sensitive to the geometry of the contact\nunlike the usual behaviour in the presence of bulk electrodes."
    },
    {
        "anchor": "Dipole coupling of a double quantum dot to a microwave resonator: Quantum coherence in solid-state systems has been demonstrated in\nsuperconducting circuits and in semiconductor quantum dots. This has paved the\nway to investigate solid-state systems for quantum information processing with\nthe potential benefit of scalability compared to other systems based on atoms,\nions and photons. Coherent coupling of superconducting circuits to microwave\nphotons, circuit quantum electrodynamics (QED), has opened up new research\ndirections and enabled long distance coupling of qubits. Here we demonstrate\nhow the electromagnetic field of a superconducting microwave resonator can be\ncoupled to a semiconductor double quantum dot. The charge stability diagram of\nthe double dot, typically measured by direct current (DC) transport techniques,\nis investigated via dispersive frequency shifts of the coupled resonator. This\nhybrid all-solid-state approach offers the potential to coherently couple\nmultiple quantum dot and superconducting qubits together on one chip, and\noffers a method for high resolution spectroscopy of semiconductor quantum\nstructures.",
        "positive": "Topological Charge Analysis of Ultrafast Single Skyrmion Creation: Magnetic skyrmions are topologically non-trivial spin textures of potential\ninterest for future information storage applications, and for such purposes,\nthe control and understanding of single skyrmion creation is required. A scheme\nis analyzed to create single N\\'{e}el-type and Bloch-type skyrmions in\nhelimagnetic thin films utilizing the dynamical excitations induced by the\nOersted field and the spin transfer torque given by a vertically injected\nspin-polarized current. A topological charge analysis using a lattice version\nof the topological charge provides insight into the locally triggered\ntransition from a trivial to a non-trivial topological spin texture of the\nN\\'{e}el or Bloch type skyrmion. The topological protection of the magnetic\nskyrmion is determined by the symmetric Heisenberg exchange energy. The\ncritical switching current density is $\\sim10^{7}\\thinspace\\textrm{A/cm}^{2}$,\nwhich decreases with the easy-plane type uniaxial anisotropy and thermal\nfluctuations. In-plane spin polarization of the injected current performs\nbetter than out-of-plane polarization, and it provides ultrafast switching\ntimes (within 100 ps) and reliable switching outcomes."
    },
    {
        "anchor": "Microwave-induced pi-junction transition in a superconductor /\n  quantum-dot / superconductor structure: Using the nonequilibrium Green function, we show that microwave irradiation\ncan reverse the supercurrent flowing through a superconductor / quantum-dot /\nsuperconductor structure. In contrast with the conventional sideband effect in\nnormal-metal / quantum-dot / normal-metal junctions, the photon-assisted\nstructures appear near $E_{0}=\\frac{n}{2}\\hbar \\omega (n=\\pm 1,\\pm 2...)$,\nwhere $E_{0}$ is the resonant energy level of the quantum dot and $\\omega $ is\nthe frequency of microwave field. Each photon-assisted structure is composed of\na negative and a positive peak, with an abrupt jump from the negative peak to\nthe positive peak around $E_{0}=\\frac{n}{2}\\hbar \\omega $. The\nmicrowave-induced $\\pi $-junction transition is interpreted in the picture of\nphoton-assisted Andreev bound states, which are formed due to multiple\nphoton-assisted Andreev reflection between the two superconductors. Moreover,\nthe main resonance located at $E_{0}=0$ can also be reversed with proper\nmicrowave strength and frequency.",
        "positive": "Temperature dependence and mechanism of electrically detected ESR at the\n  n=1 filling factor of a two-dimensional electron system in GaAs quantum wells: Electrically detected electron spin resonance (EDESR) signals were acquired\nas a function of temperature in the 0.3-4.2 K temperature range in a\nAlGaAs/GaAs multiple quantum well sample at the filling factor at 5.7 T. In the\nparticular sample studied, the line width is approximately temperature\nindependent, while the amplitude exhibits a maximum at about 2.2 K and vanishes\nwith increased or decreased temperature. To explain the observed temperature\ndependence of the signal amplitude, the signal amplitude temperature dependence\nis calculated assuming a model based on heating. The model ascribes the\nresonant absorption of microwave power of the 2DES to the uniform mode of the\nelectron spin magnetization where the elementary spin excitations at filling\nfactor are taken to be spin waves, while the short wavelength spin wave modes\nserve as a heat sink for the absorbed energy. Due to the finite thermal\nconductance to the surroundings, the temperature of the 2DES spin wave system\nis increased, resulting in a thermal activation of the longitudinal\nmagnetoconductance. The proposed heating model correctly predicts the location\nof the maximum in the experimentally observed temperature dependence of the\nEDESR amplitude. It also correctly predicts that the signal should vanish as\nthe temperature is increased or decreased. The results of the present study\ndemonstrate how experimental EDESR studies can, under appropriate conditions,\nprovide data that can be used to discriminate between competing theories for\nthe magnetic ordering and magnetic excitations of a 2DES in the regime of the\nquantum Hall effect."
    },
    {
        "anchor": "Spin-orbit coupling assisted by flexural phonons in graphene: We analyze the couplings between spins and phonons in graphene. We present a\ncomplete analysis of the possible couplings between spins and flexural, out of\nplane, vibrations. From tight-binding models we obtain analytical and numerical\nestimates of their strength. We show that dynamical effects, induced by quantum\nand thermal fluctuations, significantly enhance the spin-orbit gap.",
        "positive": "Perspectives for gapped bilayer graphene polaritonics: Bilayer graphene is normally a semimetal with parabolic dispersion, but a\ntunable bandgap up to few hundreds meV can be opened by breaking the symmetry\nbetween the layers through an external potential. Ab-initio calculations show\nthat the optical response around the bandgap is strongly dominated by bound\nexcitons, whose characteristics and selection rules differ from the usual\nexcitons found in semiconductor quantum wells. In this work we study the\nphysics of those excitons resonantly coupled to a photonic microcavity,\nassessing the possibility to reach the strong and the ultrastrong coupling\nregimes of light-matter interaction. We discover that both regimes are\nexperimentally accessible, thus opening the way for a most promising\ntechnological platform, combining mid-infrared quantum polaritonics with the\ntunability and electronic features of graphene bilayers."
    },
    {
        "anchor": "Pressure-Induced Insulator-to-Metal Transition Provides Evidence for\n  Negative-$U$ Centers in Large-Gap Disordered Insulators: Attractive negative-$U$ interactions between electrons facilitated by strong\nelectron-phonon interaction are common in highly polarizable and disordered\nmaterials such as amorphous chalcogenides, but there is no direct evidence for\nthem in large-band-gap insulators. Here we report how such negative-$U$ centers\nare responsible for widespread insulator-to-metal transitions in amorphous\nHfO$_2$ and Al$_2$O$_3$ thin films with a 10$^9$-fold resistance drop.\nTriggered by a static hydraulic pressure or a 0.1 ps impulse of magnetic\npressure, the transition can proceed at such low pressure that there is very\nlittle overall deformation (strain~10$^{-5}$). Absent a significant energy\nchange overall, the transition is attributed to the reversal of localized\nelectron-phonon interaction: By reversing the sign of $U$, trapped electrons\nare destabilized and released, thus clearing conduction paths previously\nblocked by charged traps. The results also suggest that Mott insulators when\ndisordered may become Anderson insulators with strong electron-phonon\ninteractions regulating incipient conduction paths, a novel finding of\ntechnological significance for electronic devices.",
        "positive": "Controlled nanostructures at La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ thin film\n  surfaces formed by STM lithography: Nanoscale lithography on La$_{0.7}$Sr$_{0.3}$MnO$_{3}$ (LSMO) thin film\nsurfaces has been performed by scanning tunneling microscopy under ambient\nconditions. From line-etching experiments we found that the line depth is\nincreasing in a step-wise fashion with increasing bias voltage as well as with\ndecreasing scan speed. On average, the depth of the etched lines is an integral\nmultiple of the LSMO out-of-plane lattice constant about 0.4 nm. A minimum wall\nthickness of 1.5 nm was obtained between etched lines. We have utilized the\nability to control the etched line depths to create complicated inverse-pyramid\nnanostructure. Our work shows the feasibility of using STM lithography to\ncreate controllable and complex nanoscale structures in LSMO thin film."
    },
    {
        "anchor": "Mesoscopic spin Hall effect along a potential step in graphene: We consider a straight one-dimensional potential step created across a\ngraphene flake. Charge and spin transport through such a potential step are\nstudied in the presence of both intrinsic and extrinsic (Rashba) spin-orbit\ncoupling (SOC). At normal incidence electrons are completely reflected when the\nRashba interaction (with strength $\\lambda_R$) is dominant whereas they are\nperfectly transmitted if the two types of SOC are exactly balanced. At normal\nincidence, the transmission probability of the step is thus controlled\ncontinuously from 0 to 1 by tuning the ratio of the two types of SOC. Besides\nthe transport of charge in the direction normal to the barrier, we show the\nexistence of a spin transport along the barrier. The magnitude of the spin Hall\ncurrent is determined by a subtle interplay between the height of the potential\nstep and the position of Fermi energy. It is demonstrated that contributions\nfrom inter-band matrix elements and evanescent modes are dominant in spin\ntransport. Moreover, in the case of vanishing extrinsic SOC ($\\lambda_R =0$),\neach channel carries a conserved spin current, in contrast to the general case\nof a finite $\\lambda_R$, in which only integrated spin current is a conserved\nquantity. Finally, we provide a quasi-classical picture of the charge and spin\ntransport by imaging flow lines over the entire sample and Veselago lensing\n(negative refraction) in the case of a $p-n$ junction.",
        "positive": "Atomic rheology of gold nanojunctions: Despite extensive investigations of dissipation and deformation processes in\nmicro- and nano- sized metallic samples, the mechanisms at play during\ndeformation of systems with ultimate, molecular size remain elusive. While\nmetallic nanojunctions, obtained by stretching metallic wires down to the\natomic level are a system of choice to explore atomic scale contacts, it has\nnot been possible up to now to extract the full equilibrium and out of\nequilibrium rheological flow properties of matter at such scales. Here, by\nusing a quartz-tuning fork based Atomic Force Microscope (TF-AFM), we combine\nelectrical and rheological measurement on angstr\\\"om-size gold junctions to\nstudy the non linear rheology of this model atomic system. By submitting the\njunction to increasing sub-nanometric deformations we uncover a transition from\na purely elastic regime to a plastic, and eventually to a viscous-like\nfluidized regime, akin to the rheology of soft yielding materials, though\norders of magnitude difference in length scale. The fluidized state furthermore\nhighlights capillary attraction, as expected for liquid capillary bridges. This\nshear fluidization cannot be captured by classical models of friction between\natomic planes, pointing to unexpected dissipative behavior of defect-free\nmetallic junctions at the ultimate scales. Atomic rheology is therefore a\npowerful tool to probe the structural reorganization of atomic contacts."
    },
    {
        "anchor": "Electric gating induced bandgaps and enhanced Seebeck effect in zigzag\n  bilayer graphene ribbons: We theoretically investigate effect of a transverse electric field generated\nby side gates and a vertical electric field generated by top, back gates on\nenergy bands and transport properties of zigzag bilayer graphene ribbons\n(Bernal stacking). Using atomistic Tight Binding calculations and Green\nfunction formalism we demonstrate that bandgap is opened when either field is\napplied and even enlarged under simultaneous influence of the two fields.\nInterestingly, although vertical electric fields are widely used to control\nbandgap in bilayer graphene, here we show that transverse fields exhibit more\npositive effect in terms of modulating a larger range of bandgap and retaining\ngood electrical conductance. Seebeck effect is also demonstrated to be enhanced\nstrongly about 13 times for a zigzag bilayer graphene ribbons with 16 chain\nlines. These results may motivate new designs of devices made of bilayer\ngraphene ribbons using electric gates.",
        "positive": "Spin excitations in 3d transition-metal adatoms on Pt(111): Observable\n  with inelastic scanning tunneling spectroscopy or not?: Spin excitations in atomic-scale nanostructures have been investigated with\ninelastic scanning tunneling spectroscopy, sometimes with conflicting results.\nIn this work we present a theoretical viewpoint on a recent experimental\ncontroversy regarding the spin excitations of Co adatoms on Pt(111). While one\ngroup [Balashov et al., Phys. Rev. Lett. \\textbf{102}, 257203 (2009)] claims to\nhave detected them, another group reported their observation only after the\nhydrogenation of the Co adatom [Dubout et al., Phys. Rev. Lett. \\textbf{114},\n106807 (2015)]. Utilizing time-dependent density functional theory in\ncombination with many-body perturbation theory we demonstrate that, although\ninelastic spin excitations are possible for Cr, Mn, Fe, and Co adatoms, their\nefficiency differs. While the excitation signature is less pronounced for Mn\nand Co adatoms, it is larger for Cr and Fe adatoms. We find that the tunneling\nmatrix elements related to the nature and symmetry of the relevant electronic\nstates are more favorable for triggering the spin excitations in Fe than in Co.\nAn enhancement of the tunneling and of the inelastic spectra is possible by\nattaching hydrogen to the adatom at the appropriate position."
    },
    {
        "anchor": "Spin Relaxation due to Charge Noise: We study decoherence of an electron spin qubit in a quantum dot due to charge\nnoise. We find that at the lowest order, the pure dephasing channel is\nsuppressed for both $1/f$ charge noise and Johnson noise, so that charge noise\nleads to a pure relaxation channel of decoherence. Because of the weaker\nmagnetic field dependence, the spin relaxation rate due to charge noise could\ndominate over phonon noise at low magnetic fields in a gate-defined GaAs or Si\nquantum dot or a InAs self-assembled quantum dot. Furthermore, in a large InAs\nself-assembled quantum dot, the spin relaxation rate due to phonon noise could\nbe suppressed in high magnetic field, and the spin relaxation due to charge\nnoise could dominate in both low and high magnetic field. Numerically, in a 1\nTesla field, the spin relaxation time due to typical charge noise is about\n$100$ s in Si, $0.1$ s in GaAs for a gate-defined quantum dot with a $1$ meV\nconfinement, and $10$ $\\mu$s in InAs self-assembled quantum dot with a $4$ meV\nconfinement.",
        "positive": "Resonant tunneling in short Josephson SFS junctions: Josephson effect in short ballistic SINIS and SIFIS double-tunnel junctions,\nconsisting of clean superconductors (S), a normal metal (N) or metallic\nferromagnet (F), and insulating interfaces (I) is studied. For SINIS\ndouble-tunnel junctions, sharp peaks in the critical Josephson current as a\nfunction of the junction width result from the resonant amplification of the\nAndreev process when the quasi-bound states enter the superconducting gap. For\nSIFIS double-tunnel junctions spin split quasi-bound states partially amplify\nthe supercurrent and trigger the transitions between 0 and $\\pi$ states of the\njunction. Instead of the critical current reaching a peak value (which happens\nwhen the Andreev states cross the Fermi surface in SINIS junctions), a narrow\ndip opens up exactly at the peak due to the compensation of partial currents\nflowing in opposite directions. This is related to the spin polarization of\nAndreev states and explains the coexistence of stable and metastable 0 and\n$\\pi$ states in the vicinity of the transition. With increased barrier\ntransparency, the described mechanism of $0-\\pi$ transitions is modified by the\nbroadening and overlapping of quasi-bound states (transmission resonances).\nTemperature-induced transitions both from 0 to $\\pi$ and from $\\pi$ to 0 states\nare studied by computing the phase diagram (temperature vs. junction width) for\ndifferent interfacial transparencies varying from metallic (transparent) to the\ntunnel limit."
    },
    {
        "anchor": "Detection of spin bias in four-terminal quantum-dot ring: In this work, we show that in a four-quantum-dot ring, via introducing a\nlocal Rashba spin-orbit interaction the spin bias in the transverse terminals\ncan be detected by observing the charge currents in the longitudinal probes. It\nis found that due to the Rashba interaction, the quantum interference in this\nsystem becomes spin-dependent and the opposite-spin currents induced by the\nspin bias can present different magnitudes, so charge currents emerge. Besides,\nthe charge currents rely on both the magnitude and spin polarization direction\nof the spin bias. It is believed that this method provides an electrical but\npractical scheme to detect the spin bias (or the spin current).",
        "positive": "Impurity states and Localization in Bilayer Graphene: the Low Impurity\n  Concentration Regime: We study the problem of non-magnetic impurities adsorbed on bilayer graphene\nin the diluted regime. We analyze the impurity spectral densities for various\nconcentrations and gate fields. We also analyze the effect of the adsorbate on\nthe local density of states (LDOS) of the different C atoms in the structure\nand present some evidence of strong localization for the electronic states with\nenergies close to the Dirac point."
    },
    {
        "anchor": "Negative Magnetoresistance without Chiral Anomaly in Topological\n  Insulators: An intriguing phenomenon in topological semimetals and topological insulators\nis the negative magnetoresistance (MR) observed when a magnetic field is\napplied along the current direction. A prevailing understanding to the negative\nMR in topological semimetals is the chiral anomaly, which, however, is not well\ndefined in topological insulators. We calculate the MR of a three-dimensional\ntopological insulator, by using the semiclassical equations of motion, in which\nthe Berry curvature explicitly induces an anomalous velocity and orbital\nmoment. Our theoretical results are in quantitative agreement with the\nexperiments. The negative MR is not sensitive to temperature and increases as\nthe Fermi energy approaches the band edge. The orbital moment and g factors\nalso play important roles in the negative MR. Our results give a reasonable\nexplanation to the negative MR in 3D topological insulators and will be helpful\nin understanding the anomalous quantum transport in topological states of\nmatter.",
        "positive": "Intrinsically Undamped Plasmon Modes in Narrow Electron Bands: Surface plasmons in 2-dimensional electron systems with narrow Bloch bands\nfeature an interesting regime in which Landau damping (dissipation via\nelectron-hole pair excitation) is completely quenched. This surprising behavior\nis made possible by strong coupling in narrow-band systems characterized by\nlarge values of the \"fine structure\" constant $\\alpha=e^2/\\hbar \\kappa v_{\\rm\nF}$. Dissipation quenching occurs when dispersing plasmon modes rise above the\nparticle-hole continuum, extending into the forbidden energy gap that is free\nfrom particle-hole excitations. The effect is predicted to be prominent in\nmoir\\'e graphene, where at magic twist-angle values, flat bands feature\n$\\alpha\\gg1$. The extinction of Landau damping enhances spatial optical\ncoherence. Speckle-like interference, arising in the presence of disorder\nscattering, can serve as a telltale signature of undamped plasmons directly\naccessible in near-field imaging experiments."
    },
    {
        "anchor": "Controlling Topology through Targeted Symmetry Manipulation in Magnetic\n  Systems: The possibility of selecting magnetic space groups by orienting the\nmagnetization direction or tuning magnetic orders offers a vast playground for\nengineering symmetry protected topological phases in magnetic materials. In\nthis work, we study how selective tuning of symmetry and magnetism can\ninfluence and control the resulting topology in a 2D magnetic system, and\nillustrate such procedure in the ferromagnetic monolayer MnPSe$_3$. Density\nfunctional theory calculations reveals a symmetry-protected accidental\nsemimetalic (SM) phase for out-of-plane magnetization which becomes an\ninsulator when the magnetization is tilted in-plane, reaching band gap values\nclose to $100$ meV. We identify an order-two composite antiunitary symmetry and\nthreefold rotational symmetry that induce the band crossing and classify the\npossible topological phases using symmetry analysis, which we support with\ntight-binding and $\\mathbf{k}\\cdot\\mathbf{p}$ models. Breaking of inversion\nsymmetry opens a gap in the SM phase, giving rise to a Chern insulator. We\ndemonstrate this explicitly in the isostructural Janus compound\nMn$_2$P$_2$S$_3$Se$_3$, which naturally exhibits Rashba spin-orbit coupling\nthat breaks inversion symmetry. Our results map out the phase space of\ntopological properties of ferromagnetic transition metal phosphorus\ntrichalcogenides and demonstrate the potential of the magnetization-dependent\nmetal-to-insulator transition as a spin switch in integrated two-dimensional\nelectronics.",
        "positive": "Graphene-based Josephson junction microwave bolometer: Sensitive microwave detectors are critical instruments in radioastronomy,\ndark matter axion searches, and superconducting quantum information science.\nThe conventional strategy towards higher-sensitivity bolometry is to\nnanofabricate an ever-smaller device to augment the thermal response. However,\nthis direction is increasingly more difficult to obtain efficient photon\ncoupling and maintain the material properties in a device with a large\nsurface-to-volume ratio. Here we advance this concept to an ultimately thin\nbolometric sensor based on monolayer graphene. To utilize its minute electronic\nspecific heat and thermal conductivity, we develop a\nsuperconductor-graphene-superconductor (SGS) Josephson junction bolometer\nembedded in a microwave resonator of resonant frequency 7.9 GHz with over 99\\%\ncoupling efficiency. From the dependence of the Josephson switching current on\nthe operating temperature, charge density, input power, and frequency, we\ndemonstrate a noise equivalent power (NEP) of 7 $\\times 10^{-19}$ W/Hz$^{1/2}$,\ncorresponding to an energy resolution of one single photon at 32 GHz and\nreaching the fundamental limit imposed by intrinsic thermal fluctuation at 0.19\nK."
    },
    {
        "anchor": "Friedel oscillations induced surface magnetic anisotropy: We present detailed numerical studies of the magnetic anisotropy energy of a\nmagnetic impurity near the surface of metallic hosts (Au and Cu), that we\ndescribe in terms of a realistic tight-binding surface Green's function\ntechnique. We study the case when spin-orbit coupling originates from the\nd-band of the host material and we also investigate the case of a strong local\nspin-orbit coupling on the impurity itself. The splitting of the impurity's\nspin-states is calculated to leading order in the exchange interaction between\nthe impurity and the host atoms using a diagrammatic Green's function\ntechnique. The magnetic anisotropy constant is an oscillating function of the\nseparation d from the surface: it asymptotically decays as 1/d2 and its\noscillation period is determined by the extremal vectors of the host's Fermi\nSurface. Our results clearly show that the host-induced magnetic anisotropy\nenergy is by several orders of magnitude smaller than the anisotropy induced by\nthe local mechanism, which provides sufficiently large anisotropy values to\nexplain the size dependence of the Kondo resistance observed experimentally.",
        "positive": "Purcell effect at metal-insulator transitions: We investigate the spontaneous emission rate of a two-level quantum emitter\nnext to a composite medium made of randomly distributed metallic inclusions\nembedded in a dielectric host matrix. In the near-field, the Purcell factor can\nbe enhanced by two-orders of magnitude relative to the case of an homogeneous\nmetallic medium, and reaches its maximum precisely at the insulator-metal\ntransition. By unveiling the role of the decay pathways on the emitter's\nlifetime, we demonstrate that, close to the percolation threshold, the\nradiation emission process is dictated by electromagnetic absorption in the\nheterogeneous medium. We show that our findings are robust against change in\nmaterial properties, shape of inclusions, and apply for different effective\nmedium theories as well as for a wide range of transition frequencies."
    },
    {
        "anchor": "Stationary waves in a superfluid exciton gas in quantum Hall bilayers: Stationary waves in a superfluid magnetoexciton gas in nu = 1 quantum Hall\nbilayers are considered. The waves are induced by counter-propagating\nelectrical currents that flow in a system with a point obstacle. It is shown\nthat stationary waves can emerge only in imbalanced bilayers in a certain\ndiapason of currents. It is found that the stationary wave pattern is modified\nqualitatively under a variation of the ratio of the interlayer distance to the\nmagnetic length d/l. The advantages of use graphene-dielectric-graphene\nsandwiches for the observation of stationary waves are discussed. We determine\nthe range of parameters (the dielectric constant of the layer that separates\ntwo graphene layers and the ratio d/l) for which the state with superfluid\nmagnetoexcitons can be realized in such sandwiches. Typical stationary wave\npatterns are presented as density plots",
        "positive": "Probing Majorana localization in minimal Kitaev chains through a quantum\n  dot: Artificial Kitaev chains, formed by quantum dots coupled via superconductors,\nhave emerged as a promising platform for realizing Majorana bound states. Even\na minimal Kitaev chain (a quantum dot--superconductor--quantum dot setup) can\nhost Majorana states at discrete sweet spots. However, unambiguously\nidentifying Majorana sweet spots in such a system is still challenging. In this\nwork, we propose an additional dot coupled to one side of the chain as a tool\nto identify good sweet spots in minimal Kitaev chains. When the two Majorana\nstates in the chain overlap, the extra dot couples to both and thus splits an\neven--odd ground-state degeneracy when its level is on resonance. In contrast,\na ground-state degeneracy will persist for well-separated Majorana states. This\ndifference can be used to identify points in parameter space with spatially\nseparated Majorana states, using tunneling spectroscopy measurements. We\nperform a systematic analysis of different relevant situations. We show that\nthe additional dot can help distinguishing between Majorana sweet spots and\nother trivial zero-energy crossings. We also characterize the different\nconductance patterns, which can serve as a guide for future experiments aiming\nto study Majorana states in minimal Kitaev chains."
    },
    {
        "anchor": "Tunable Graphene Single Electron Transistor: We report electronic transport experiments on a graphene single electron\ntransistor. The device consists of a graphene island connected to source and\ndrain electrodes via two narrow graphene constrictions. It is electrostatically\ntunable by three lateral graphene gates and an additional back gate. The\ntunneling coupling is a strongly nonmonotonic function of gate voltage\nindicating the presence of localized states in the barriers. We investigate\nenergy scales for the tunneling gap, the resonances in the constrictions and\nfor the Coulomb blockade resonances. From Coulomb diamond measurements in\ndifferent device configurations (i.e. barrier configurations) we extract a\ncharging energy of 3.4 meV and estimate a characteristic energy scale for the\nconstriction resonances of 10 meV.",
        "positive": "Directional Interlayer Spin-Valley Transfer in Two-Dimensional\n  Heterostructures: Van der Waals heterostructures formed by two different monolayer\nsemiconductors have emerged as a promising platform for new optoelectronic and\nspin/valleytronic applications. In addition to its atomically thin nature, a\ntwo-dimensional semiconductor heterostructure is distinct from its\nthree-dimensional counterparts due to the unique coupled spin-valley physics of\nits constituent monolayers. Here, we report the direct observation that an\noptically generated spin-valley polarization in one monolayer can be\ntransferred between layers of a two-dimensional MoSe2-WSe2 heterostructure.\nUsing nondegenerate optical circular dichroism spectroscopy, we show that\ncharge transfer between two monolayers conserves spin-valley polarization and\nis only weakly dependent on the twist angle between layers. Our work points to\na new spin-valley pumping scheme in nanoscale devices, provides a fundamental\nunderstanding of spin-valley transfer across the two-dimensional interface, and\nshows the potential use of two-dimensional semiconductors as a spin-valley\ngenerator in 2D spin/valleytronic devices for storing and processing\ninformation."
    },
    {
        "anchor": "Light Induced Negative Differential Conductance in Molecular Junctions:\n  Role of Triplet States and Electron-Phonon Interaction: In this work we theoretically consider the OPE-3 molecule bridging two\nmetallic leads and show that because of the electron-phonon interaction and the\ntransition of cation to triplet states, we can have a light induced negative\ndifferential conductance. Furthermore, we investigate the effects of light\nintensity and temperature on this phenomena.",
        "positive": "Synthetic spin orbit interaction for Majorana devices: The interplay of superconductivity with a non-trivial spin texture holds\npromises for the engineering of non-abelian Majorana quasi-particles. A wide\nclass of systems expected to exhibit exotic correlations are based on nanoscale\nconductors with strong spin-orbit interaction, subject to a strong external\nmagnetic field. The strength of the spin-orbit coupling is a crucial parameter\nfor the topological protection of Majorana modes as it forbids other trivial\nexcitations at low energy. The spin-orbit interaction is in principle intrinsic\nto a material. As a consequence, experimental efforts have been recently\nfocused on semiconducting nano-conductors or spin-active atomic chains\ncontacted to a superconductor. Alternatively, we show how both a spin-orbit and\na Zeeman effect can be autonomously induced by using a magnetic texture coupled\nto any low dimensional conductor, here a carbon nanotube. Transport\nspectroscopy through superconducting contacts reveals oscillations of Andreev\nlike states under a change of the magnetic texture. These oscillations are well\naccounted for by a scattering theory and are absent in a control device with no\nmagnetic texture. A large synthetic spin-orbit energy of about 1.1 meV, larger\nthan the intrinsic spin orbit energy in many other platforms, is directly\nderived from the number of oscillations. Furthermore, a robust zero energy\nstate, the hallmark of devices hosting localized Majorana modes, emerges at\nzero magnetic field. Our findings synthetize all the features for the emergence\nof Majorana modes at zero magnetic field in a controlled, local and autonomous\nfashion. It could be used for advanced experiments, including microwave\nspectroscopy and braiding operations, which are at the heart of new schemes of\ntopological quantum computation."
    },
    {
        "anchor": "Emergent electromagnetism induced by topological defects created during\n  magnetization reversal in nanowires: We report that the irreversible magnetization switching process in\nferromagnetic nanoparticles is governed by the formation and dynamics of\ntopological point-defects in the form of hedgehog-antihedgehog pairs. After\nnucleation, these pairs rapidly separate with speeds exceeding domain wall\nvelocities, and they generate an emergent electric field of solenoidal\ncharacter and substantial magnitude.",
        "positive": "Transport through correlated systems with density functional theory: We present recent advances in Density Functional Theory (DFT) for\napplications to the field of quantum transport, with particular emphasis on\ntransport through strongly correlated systems. We review the foundations of the\npopular Landauer-B\\\"uttiker(LB)+DFT approach. This formalism, when using\napproximations to the exchange-correlation (xc) potential with steps at integer\noccupation, correctly captures the Kondo plateau in the zero bias conductance\nat zero temperature but completely fails to capture the transition to the\nCoulomb blockade (CB) regime as temperature increases. To overcome the\nlimitations of LB+DFT the quantum transport problem is treated from a\ntime-dependent (TD) perspective using TDDFT, an exact framework to deal with\nnonequilibrium situations. The steady-state limit of TDDFT shows that in\naddition to an xc potential in the junction, there also exists an xc correction\nto the applied bias. Open shell molecules in the CB regime provide the most\nstriking examples of the importance of the xc bias correction. Using the\nAnderson model as guidance we estimate these corrections in the limit of zero\nbias. For the general case we put forward a steady-state DFT which is based on\nthe one-to-one correspondence between the pair of basic variables steady\ndensity on and steady current across the junction and the pair local potential\non and bias across the junction. Like TDDFT, this framework also leads to both\nan xc potential in the junction and an xc correction to the bias. Unlike in\nTDDFT, these potentials are independent of history. We highlight the universal\nfeatures of both xc potential and xc bias corrections for junctions in the CB\nregime and provide an accurate parametrization for the Anderson model at\narbitrary temperatures and interaction strengths thus providing a unified DFT\ndescription for both Kondo and CB regimes and the transition between them."
    },
    {
        "anchor": "Time-dependent electron transport through a strongly correlated quantum\n  dot: multiple-probe open boundary conditions approach: We present a time-dependent study of electron transport through a strongly\ncorrelated quantum dot. The time-dependent current is obtained with the\nmultiple-probe battery method, while adiabatic lattice density functional\ntheory in the Bethe ansatz local-density approximation to the Hubbard model\ndescribes the dot electronic structure. We show that for a certain range of\nvoltages the quantum dot can be driven into a dynamical state characterized by\nregular current oscillations. This is a manifestation of a recently proposed\ndynamical picture of Coulomb blockade. Furthermore, we investigate how the\nvarious approximations to the electron-electron interaction affect the\nline-shapes of the Coulomb peaks and the I-V characteristics. We show that the\npresence of the derivative discontinuity in the approximate\nexchange-correlation potential leads to significantly different results\ncompared to those obtained at the simpler Hartree level of description. In\nparticular, a negative differential conductance (NDC) in the I-V\ncharacteristics is observed at large bias voltages and large Coulomb\ninteraction strengths. We demonstrate that such NDC originates from the\ncombined effect of electron-electron interaction in the dot and the finite\nbandwidth of the electrodes.",
        "positive": "Exciton condensation in biased bilayer graphene: We consider suspened bilayer graphene under applied perpendicular electric\nbias field that is known to generate a single particle gap $2\\Delta$ and a\nrelated electric polarization ${\\cal P}$. We argue that the bias also drives a\nquantum phase transition from band insulator to superfluid exciton condensate.\nThe transition occurs when the exciton binding energy exceeds the band gap\n$2\\Delta$. We predict the critical bias (converted to band gap),\n$\\Delta_c\\approx 60$ meV, below which the excitons condense. The critical\ntemperature, $T_c(\\Delta)$, is maximum at $\\Delta \\approx 25$ meV,\n$T_c^\\text{max}\\approx 115$ K, decreasing significantly at smaller $\\Delta$ due\nto thermal screening. Entering the condensate phase, the superfluid transition\nis accompanied by a cusp in the electric polarization ${\\cal P}(\\Delta)$ at\n$\\Delta\\to\\Delta_c$, which provides a striking testable signature.\nAdditionally, we find that the condensate prefers to form a pair density wave."
    },
    {
        "anchor": "Large photogalvanic spin current by magnetic resonance in bilayer Cr\n  trihalides: Magnetic materials show rich optical responses related to the magnetic order.\nThese phenomena reflect the nature of their excitations, providing a powerful\nprobe for the magnetic states and a way to control them. In recent years, such\nstudies were extended to the optical control of spin current using nonlinear\noptical response similar to the photogalvanic effect. However, neither a\ncandidate material nor a general formula for calculating the photogalvanic spin\ncurrent is known so far. In this work, we develop a general theory for the\nphotogalvanic spin current through a magnetic resonance process. Using the\nnonlinear response formalism, we find the nonlinear conductivity consists of\ntwo contributions that involve one and two magnon bands; the latter is a\ncontribution unknown to date. We argue that the two-band process produces a\nlarge photogalvanic spin current in the antiferromagnetic phase of bilayer\nCrI$_3$ and CrBr$_3$, whose resonance frequency can be tuned between GHz-THz\nrange by an external magnetic field. Our findings open a route to the studies\non the photogalvanic effect of spin angular momentum in realistic setups.",
        "positive": "Dynamical spin injection at a quasi-one-dimensional ferromagnet-graphene\n  interface: We present a study of dynamical spin injection from a three-dimensional\nferromagnet into two-dimensional single-layer graphene. Comparative\nferromagnetic resonance (FMR) studies of ferromagnet/graphene strips buried\nunderneath the central line of a coplanar waveguide show that the FMR linewidth\nbroadening is the largest when the graphene layer protrudes laterally away from\nthe ferromagnetic strip, indicating that the spin current is injected into the\ngraphene areas away from the area directly underneath the ferromagnet being\nexcited. Our results confirm that the observed damping is indeed a signature of\ndynamical spin injection, wherein a pure spin current is pumped into the\nsingle-layer graphene from the precessing magnetization of the ferromagnet. The\nobserved spin pumping efficiency is difficult to reconcile with the expected\nbackflow of spins according to the standard spin pumping theory and the\ncharacteristics of graphene, and constitutes an enigma for spin pumping in\ntwo-dimensional structures."
    },
    {
        "anchor": "Melting phase diagram of bubble phases in high Landau levels: A low-disorder, two-dimensional electron system (2DES) subjected to a large\nperpendicular magnetic field and cooled to very low temperatures provides a\nrich platform for studies of many-body quantum phases. The magnetic field\nquenches the electrons' kinetic energy and quantizes the energy into a set of\nLandau levels, allowing the Coulomb interaction to dominate. In excited Landau\nlevels, the fine interplay between short- and long-range interactions\nstabilizes bubble phases, Wigner crystals with more than one electron per unit\ncell. Here we present the screening properties of bubble phases, probed via a\nsimple capacitance technique where the 2DES is placed between a top and a\nbottom gate and the electric field penetrating through the 2DES is measured.\nThe bubbles formed at very low temperatures screen the electric field poorly as\nthey are pinned by the residual disorder potential, allowing a large electric\nfield to reach the top gate. As the temperature is increased, the penetrating\nelectric field decreases and, surprisingly, exhibits a pronounced minimum at a\ntemperature that appears to coincide with the melting temperature of the bubble\nphase. We deduce a quantitative phase diagram for the transition from bubble to\nliquid phases for Landau level filling factors $4\\leq\\nu\\leq5$.",
        "positive": "Probing the current-phase relation of graphene Josephson junctions using\n  microwave measurements: We perform extensive analysis of graphene Josephson junctions embedded in\nmicrowave circuits. By comparing a diffusive junction at 15 mK with a ballistic\none at 15 mK and 1 K, we are able to reconstruct the current-phase relation."
    },
    {
        "anchor": "RF Reflectometry for Readout of Charge Transition in a Physically\n  Defined PMOS Silicon Quantum Dot: We have embedded a physically defined p-channel silicon MOS quantum dot (QD)\ndevice into an impedance transformer RC circuit. To decrease the parasitic\ncapacitance and surpass the cutoff frequency of the device which emerges in MOS\ndevices that have a top gate and act as RC low-pass filter, we fabricate a new\ndevice to reduce the device's top gate area from 400 $\\mbox{$\\mu$m}^2$ to 0.09\n$\\mbox{$\\mu$m}^2$. Having a smaller top gate eliminates the cutoff frequency\nproblem preventing the RF signal from reaching QD. We show that we have\nfabricated a single QD properly, which is essential for RF single-electron\ntransistor technique. We also analyze and improve the impedance matching\ncondition and show that it is possible to perform readout of charge transition\nat 4.2 K by RF reflectometry, which will get us to fast readout of charge and\nspin states.",
        "positive": "Tunable phonon cavity coupling in graphene membranes: A major achievement of the past decade has been the realization of\nmacroscopic quantum systems by exploiting interactions between optical cavities\nand mechanical resonators. In these systems, phonons are coherently annihilated\nor created in exchange for photons. Similar phenomena have recently been\nobserved through \"phonon cavity\" coupling -- energy exchange between modes of a\nsingle system as mediated by intrinsic material nonlinearity. To date, this has\nbeen demonstrated primarily for bulk crystalline, high-quality-factor\n(Q>100,000) mechanical systems operated at cryogenic temperatures. Here we\npropose graphene as an ideal candidate for the study of such nonlinear\nmechanics. The large elastic modulus of this material and capability for\nspatial symmetry breaking via electrostatic forces is expected to generate a\nwealth of nonlinear phenomena, including tunable inter-modal coupling. We have\nfabricated circular graphene membranes and report strong phonon cavity effects\nat room temperature, despite the modest Q (~100) of this system. We observe\nboth amplification into parametric instability (\"mechanical lasing\") and\ncooling of Brownian motion in the fundamental mode through excitation of cavity\nsidebands. Furthermore, we characterize quenching of these parametric effects\nat large vibrational amplitudes, offering a window on the all-mechanical\nanalogue of cavity optomechanics, where observation of such effects has proven\nelusive."
    },
    {
        "anchor": "Quantum phase transitions in models of coupled magnetic impurities: We discuss models of interacting magnetic impurities coupled to a metallic\nhost. If twice the sum of the impurity spins is larger than the total number of\nhost screening channels, the system shows one or more quantum phase transitions\nwhere the ground-state spin changes as a function of the inter-impurity\ncouplings. The simplest example is realized by two spin-1/2 Kondo impurities\ncoupled to a single orbital of the host; this model exhibits a singlet-doublet\ntransition. We investigate the phase diagram and crossover behavior of this\nmodel and present Numerical Renormalization Group results together with general\narguments showing that the quantum phase transition is either of first order or\nof the Kosterlitz-Thouless type, depending on the symmetry of the Kondo\ncouplings. Connections to other models and possible applications are discussed.",
        "positive": "Spin-Orbit mediated spin relaxation in monolayer MoS2: We study the intra-valley spin-orbit mediated spin relaxation in monolayers\nof MoS2 within a two bands effective Hamiltonian. The intrinsic spin splitting\nof the valence band as well as a Rashba-like coupling due to the breaking of\nthe out-of-plane inversion symmetry are considered. We show that, in the hole\ndoped regime, the out-of-plane spin relaxation is not very efficient since the\nspin splitting of the valence band tends to stabilize the spin polarization in\nthis direction. We obtain spin lifetimes larger than nanoseconds, in agreement\nwith recent valley polarization experiments."
    },
    {
        "anchor": "Spin wave mode coexistence on the nano-scale: A consequence of the\n  Oersted field induced asymmetric energy landscape: It has been argued that if multiple spin wave modes are competing for the\nsame centrally located energy source, as in a nanocontact spin torque\noscillator, that only one mode should survive in the steady state. Here, the\nexperimental conditions necessary for mode coexistence are explored. Mode\ncoexistence is facilitated by the local field asymmetries induced by the\nspatially inhomogeneous Oersted field, which leads to a physical separation of\nthe modes, and is further promoted by spin wave localization at reduced applied\nfield angles. Finally, both simulation and experiment reveal a low frequency\nsignal consistent with the intermodulation of two coexistent modes.",
        "positive": "Investigation of Supercurrent in the Quantum Hall Regime in Graphene\n  Josephson Junctions: In this study, we examine multiple encapsulated graphene Josephson junctions\nto determine which mechanisms may be responsible for the supercurrent observed\nin the quantum Hall (QH) regime. Rectangular junctions with various widths and\nlengths were studied to identify which parameters affect the occurrence of QH\nsupercurrent. We also studied additional samples where the graphene region is\nextended beyond the contacts on one side, making that edge of the mesa\nsignificantly longer than the opposite edge. This is done in order to\ndistinguish two potential mechanisms: a) supercurrents independently flowing\nalong both non-contacted edges of graphene mesa, and b) opposite sides of the\nmesa being coupled by hybrid electron-hole modes flowing along the\nsuperconductor/graphene boundary. The supercurrent appears suppressed in\nextended junctions, suggesting the latter mechanism."
    },
    {
        "anchor": "Transport and optical response of molecular junctions driven by surface\n  plasmon-polaritons: We consider a biased molecular junction subjected to external time-dependent\nelectromagnetic field. The field for two typical junction geometries (bowtie\nantennas and metal nanospheres) is calculated within finite-difference\ntime-domain technique. Time-dependent transport and optical response of the\njunctions is calculated within non-equilibrium Green's function approach\nexpressed in a form convenient for description of multi-level systems. We\npresent numerical results for a two-level (HOMO-LUMO) model, and discuss\ninfluence of localized surface plasmon polariton modes on transport.",
        "positive": "Signatures of defect-localized charged excitons in the photoluminescence\n  of monolayer molybdenum disulfide: We study spatial photoluminescence characteristics of neutral and charged\nexcitons across extended monolayer MoS$_2$ synthesized by chemical vapor\ndeposition. Using two-dimensional hyperspectral photoluminescence mapping at\ncryogenic temperatures we identify regions with increased emission from charged\nexcitons associated with both spin-orbit split valence subbands. Such regions\nare attributed to unintentional doping at defect sites with excess charge that\nbind neutral excitons to form defect-pinned trions. Our findings imply\ncomparable timescales for the formation, relaxation, and radiative decay of $B$\ntrions, and add defect-localized $A$ and $B$ trions to the realm of\nphotoexcited quasiparticles in layered semiconductors."
    },
    {
        "anchor": "Possible gapless helical edge states in hydrogenated graphene: Electronic band structures in hydrogenated graphene are theoretically\ninvestigated by means of first-principle calculations and an effective\ntight-binding model. It is shown that regularly designed hydrogenation to\ngraphene gives rise to a large band gap about 1 eV. Remarkably, by changing the\nspatial pattern of the hydrogenation, topologically distinct states can be\nrealized, where the topological nontriviality is detected by $C_2$ parity\nindices in bulk and confirmed by the existence of gapless edge/interface states\nas protected by the mirror and sublattice symmetries. The analysis of the wave\nfunctions reveals that the helical edge states in hydrogenated graphene with\nthe appropriate design carry pseudospin currents that are reminiscent of the\nquantum spin Hall effect. Our work shows the potential of hydrogenated graphene\nin pseudospin-based device applications.",
        "positive": "Control of quantum interference in molecular junctions: Understanding\n  the origin of Fano and anti- resonances: We investigate within a coarse-grained model the conditions leading to the\nappearance of Fano resonances or anti-resonances in the conductance spectrum of\na generic molecular junction with a side group (T-junction). By introducing a\nsimple graphical representation (parabolic diagram), we can easily visualize\nthe relation between the different electronic parameters determining the\nregimes where Fano resonances or anti-resonances in the low-energy conductance\nspectrum can be expected. The results obtained within the coarse-grained model\nare validated using density-functional based quantum transport calculations in\nrealistic T-shaped molecular junctions."
    },
    {
        "anchor": "On the nature of wettability of van der Waals heterostructures: Wetting behaviour of surfaces is believed to be affected by van der Waals\n(vdW) forces, however, there is no clear demonstration of this. With the\nisolation of two-dimensional vdW layered materials it is possible to test this\nhypothesis. In this paper, we report the wetting behaviour of vdW\nheterostructures which include, chemical vapor deposition (CVD) grown graphene,\nmolybdenum disulfide (MoS2) and tungsten disulfide (WS2) on few layers of\nhexagon boron nitride (h-BN) and SiO2/Si. Our study clearly shows that while\nthis class of two-dimensional materials are not wetting transparent, there\nseems to be a significant amount of influence on their wetting properties by\nthe underlying substrate due to dominant vdW forces. Contact angle measurements\nindicate that graphene and graphene-like layered transitional metal\ndichalcogenides invariably have intrinsically dispersive surfaces with a\ndominating London-vdW force-mediated wettability. Electric field controlled\nwetting studies of MoS2/WS2/SiO2/Si heterostructures were performed and no\nnotable changes to the water contact angle was seen with applied voltage\nalthough two orders of magnitude change in resistance was observed. We\npostulate that the highly dispersive nature of these surfaces arising from the\npredominant London-vdW forces could be the reason for such observation.",
        "positive": "Collective skyrmion motion under the influence of an additional\n  interfacial spin-transfer torque: Here we study the effect of an additional interfacial spin-transfer torque,\nas well as the well established spin-orbit torque and bulk spin-transfer\ntorque, on skyrmion collections - group of skyrmions dense enough that they are\nnot isolated from on another - in ultrathin heavy metal / ferromagnetic\nmultilayers, by comparing modelling with experimental results. Using a skyrmion\ncollection with a range of skyrmion diameters and landscape disorder, we study\nthe dependence of the skyrmion Hall angle on diameter and velocity, as well as\nthe velocity as a function of diameter. We show the experimental results are in\ngood agreement with modelling when including the interfacial spin-transfer\ntorque, and cannot be reproduced by using the spin-orbit torque alone. We also\nshow that for skyrmion collections the velocity is approximately independent of\ndiameter, in marked contrast to the motion of isolated skyrmions, as the group\nof skyrmions move together at an average group velocity. Moreover, the\ncalculated skyrmion velocities are comparable to those obtained in experiments\nwhen the interfacial spin-transfer torque in included, whilst modelling using\nthe spin-orbit torque alone shows large discrepancies with the experimental\ndata. Our results thus show the significance of the interfacial spin-transfer\ntorque in ultrathin magnetic multilayers, which is of similar strength to the\nspin-orbit torque, and both significantly larger than the bulk spin-transfer\ntorque. Due to the good agreement with experiments, we conclude that the\ninterfacial spin-transfer torque should be included in numerical modelling for\ncorrect reproduction of experimental results."
    },
    {
        "anchor": "Non-Hermiticity stabilized Majorana zero modes in\n  semiconductor-superconductor nanowires: Coupled Majorana zero modes with nonzero energies are generally detrimental\nto the non-Abelian statistics due to the additional dynamic phase.\nNevertheless, we show that a well-connected lead can introduce a local\nnon-Hermitian dissipation term to shift the energies of the both coupled\nMajorana modes to zero, and surprisingly turn the coupled Majorana mode far\nfrom the lead into a dark Majorana mode with exponentially small dissipation.\nThis dark Majorana mode can conquer the drawback of the partially overlapped\nMajorana zero modes and possess the properties of true Majorana zero mode such\nas the perfect fractional Josephson effect and the non-Abelian statistics.",
        "positive": "Photocurrent and Photoconductance Properties of a GaAs Nanowire: We report on photocurrent and photoconductance processes in a freely\nsuspended p-doped single GaAs nanowire. The nanowires are grown by molecular\nbeam epitaxy (MBE), and they are electrically contacted by a focused ion beam\n(FIB) deposition technique. The observed photocurrent is generated at the\nSchottky contacts between the nanowire and metal source-drain electrodes, while\nthe observed photoconductance signal can be explained by a photogating effect\ninduced by optically generated charge carriers located at the surface of the\nnanowire. Both optoelectronic effects are sensitive to the polarization of the\nexciting laser field, enabling polarization dependent photodetectors."
    },
    {
        "anchor": "Excitation gaps in fractional quantum Hall states: An exact\n  diagonalization study: We compute energy gaps for spin-polarized fractional quantum Hall states in\nthe lowest Landau level at filling fractions nu=1/3, 2/5,3/7 and 4/9 using\nexact diagonalization of systems with up to 16 particles and extrapolation to\nthe infinite system-size limit. The gaps calculated for a pure Coulomb\ninteraction and ignoring finite width effects, disorder and LL mixing agree\nwith predictions of composite fermion theory provided the logarithmic\ncorrections to the effective mass are included. This is in contrast with\nprevious estimates, which, as we show, overestimated the gaps at nu=2/5 and 3/7\nby around 15%. We also study the reduction of the gaps as a result of the\nnon-zero width of the 2D layer. We show that these effects are accurately\naccounted for using either Gaussian or z*Gaussian' (zG) trial wavefunctions,\nwhich we show are significantly better variational wavefunctions than the\nFang-Howard wavefunction. For quantum well parameters typical of\nheterostructure samples, we find gap reductions of around 20%. The experimental\ngaps, after accounting heuristically for disorder,are still around 40% smaller\nthan the computed gaps. However, for the case of tetracene layers\ninmetal-insulator-semiconductor (MIS) devices we find that the measured\nactivation gaps are close to those we compute. We discuss possible reasons why\nthe difference between computed and measured activation gaps is larger in GaAs\nheterostructures than in MIS devices. Finally, we present new calculations\nusing systems with up to 18 electrons of the gap at nu=5/2 including width\ncorrections.",
        "positive": "Full counting statistics of spin transfer through ultrasmall quantum\n  dots: We analyze the spin-resolved full counting statistics of electron transfer\nthrough an ultrasmall quantum dot coupled to metallic electrodes. Modelling the\nsetup by the Anderson Hamiltonian, we explicitly take into account the onsite\nCoulomb repulsion $U$. We calculate the cumulant generating function for the\nprobability to transfer a certain number of electrons with a preselected spin\norientation during a fixed time interval. With the cumulant generating function\nat hand we are then able to calculate the spin current correlations which are\nof outmost importance in the emerging field of spintronics. We confirm the\nexisting results for the charge statistics and report the discovery of the new\ntype of correlation between the spin-up and -down polarized electrons flows,\nwhich has a potential to become a powerful new instrument for the investigation\nof the Kondo effect in nanostructures."
    },
    {
        "anchor": "Theoretical approach to the nanoporous phase diagram of carbon: Nanoporous carbon has been extensively used in a wide range of applications\nranging from water treatment to electrochemical applications, such as in energy\nstorage devices. An effort to relate structural to thermodynamical properties\nhas not been explored from an atomistic approach. In this work we present\nnumerical strategies to produce and study nanoporous carbon structures, using\nmolecular dynamics simulations and a many-body potential. We designed a\nheating-quenching procedure in a thermodynamic region bounded by the critical,\nand triple point densities of carbon to study an ensemble of 1750 atomic\narrangements produced at different densities, quench rates, and using graphite\nand diamond unit cells as precursor structures. All these samples were\nnumerically characterized through the calculation of the free volumes, surface\nareas, radial distribution functions, and structure factors. We found\nparticularly useful the potential energy dependence with $sp^3$ hybridization\ncontent, to determine structural phases through clustering methods. Three\nphases were related to graphite-like, sponge-like, and unstable states. We\nshowed that our results are compatible with available experiments and different\ntheoretical schemes, concluding that the use of Tersoff potential is a reliable\nchoice to produce nanoporous structures with low computational cost.",
        "positive": "Twisted bilayer graphene revisited: minimal two-band model for\n  low-energy bands: An accurate description of the low-energy electronic bands in twisted bilayer\ngraphene (tBLG) is of great interest due to their relation to correlated\nelectron phases, such as superconductivity and Mott-insulator behavior at\nhalf-filling. The paradigmatic model of Bistritzer and MacDonald [PNAS 108,\n12233 (2011)], based on the moir\\'e pattern formed by tBLG, predicts the\nexistence of \"magic angles\" at which the Fermi velocity of the low-energy bands\ngoes to zero, and the bands themselves become dispersionless. Here, we\nreexamine the low-energy bands of tBLG from the ab initio electronic structure\nperspective, motivated by features related to the atomic relaxation in the\nmoir\\'e pattern, namely circular regions of AA stacking, triangular regions of\nAB/BA stacking and domain walls separating the latter. We find that the bands\nare never perfectly flat and the Fermi velocity never vanishes, but rather a\n\"magic range\" exists where the lower band becomes extremely flat and the Fermi\nvelocity attains a non-zero minimum value. We propose a simple $(2+2)$-band\nmodel, comprised of two different pairs of orbitals, both on a honeycomb\nlattice: the first pair represents the low-energy bands with high localization\nat the AA sites, while the second pair represents highly dispersive bands\nassociated with domain-wall states. This model gives an accurate description of\nthe low-energy bands with few (13) parameters which are physically motivated\nand vary smoothly in the magic range. In addition, we derive an effective\ntwo-band hamiltonian which also gives an accurate description of the low-energy\nbands. This minimal two-band model affords a connection to a Hubbard-like\ndescription of the occupancy of sub-bands and can be used a basis for exploring\ncorrelated states."
    },
    {
        "anchor": "Quantized Berry winding from an emergent $\\mathcal{PT}$ symmetry: Linear crossing of energy bands occur in a wide variety of materials. In this\npaper we address the question of the quantization of the Berry winding\ncharacterizing the topology of these crossings in dimension $D=2$. Based on the\nhistorical example of $2$-bands crossing occuring in graphene, we propose to\nrelate these Berry windings to the topological Chern number of a $D=3$\ndimensional extension of these crossings. This dimensional embedding is\nobtained through a choice of a gap-opening potential. We show that the presence\nof an (emergent) $\\mathcal{PT}$ symmetry, local in momentum and antiunitary,\nallows us to relate $D=3$ Chern numbers to $D=2$ Berry windings quantized as\nmultiple of $\\pi$. We illustrate this quantization mechanism on a variety of\nthree-band crossings.",
        "positive": "Resonant tunnelling and quenching of tunnel splitting in Wess-Zumino\n  nanospin systems: We investigate the energy spectrum of the biaxial spin systems with magnetic\nfield along the hard anisotropy axis by using the complex periodic orbit\ntheory. All important features of the system appearing in whole energy range,\nsuch as oscillations of level splittings due to Wess-Zumino effect and their\nabsence at higher magnetic field etc., can be completely understood within this\nsemiclassical scheme. We find out that the fields at which the tunnelling\nquenches do not shift at higher energy levels and the absences of the quenching\nat higher magnetic field have their origin in an exact coincidence of the\nquenching field with the field of resonant tunnelling. Based on the result, we\npropose that the complete cancellation of quenching with resonant tunnelling\nwould be a general property of Wess-Zumino tunnelling systems."
    },
    {
        "anchor": "Rules for Phase Shifts of Quantum Oscillations in Topological Nodal-line\n  Semimetals: Nodal-line semimetals are topological semimetals in which band touchings form\nnodal lines or rings. Around a loop that encloses a nodal line, an electron can\naccumulate a nontrivial $\\pi$ Berry phase, so the phase shift in the\nShubnikov-de Haas (SdH) oscillation may give a transport signature for the\nnodal-line semimetals. However, different experiments have reported\ncontradictory phase shifts, in particular, in the WHM nodal-line semimetals\n(W=Zr/Hf, H=Si/Ge, M=S/Se/Te). For a generic model of nodal-line semimetals, we\npresent a systematic calculation for the SdH oscillation of resistivity under a\nmagnetic field normal to the nodal-line plane. From the analytical result of\nthe resistivity, we extract general rules to determine the phase shifts for\narbitrary cases and apply them to ZrSiS and Cu$_3$PdN systems. Depending on the\nmagnetic field directions, carrier types, and cross sections of the Fermi\nsurface, the phase shift shows rich results, quite different from those for\nnormal electrons and Weyl fermions. Our results may help exploring transport\nsignatures of topological nodal-line semimetals and can be generalized to other\ntopological phases of matter.",
        "positive": "Coulomb pseudogap in elastic 2D-2D electron tunneling in a quantizing\n  magnetic field: The electron tunneling is experimentally studied between two-dimensional\nelectron gases (2DEGs) formed in a single-doped-barrier heterostructure in the\nmagnetic fields directed perpendicular to the 2DEGs planes. It is well known\nthat the quantizing magnetic field induces the Coulomb pseudogap suppressing\nthe electron tunneling at Fermi level. In this paper we firstly present the\nexperimental results revealing the pseudogap in the electron tunneling assisted\nby elastic electron scattering on disorder."
    },
    {
        "anchor": "RKKY interaction between adsorbed magnetic impurities in graphene:\n  symmetry and strain effects: The growing interest in carbon-based spintronics has stimulated a number of\nrecent theoretical studies on the RKKY interaction in graphene, with the aim of\ndetermining the most energetically favourable alignments between embedded\nmagnetic moments. The RKKY interaction in undoped graphene decays faster than\nexpected for conventional two-dimensional materials and recent studies suggest\nthat the adsorption configurations favoured by many transition-metal impurities\nmay lead to even shorter ranged decays and possible sign-changing oscillations.\nHere we show that these features emerge in a mathematically transparent manner\nwhen the symmetry of the configurations is included in the calculation.\nFurthermore, we show that by breaking the symmetry of the graphene lattice, via\nuniaxial strain, the decay rate, and hence the range, of the RKKY interaction\ncan be significantly altered. Our results suggest that magnetic interactions\nbetween adsorbed impurities in graphene can be manipulated by careful strain\nengineering of such systems.",
        "positive": "Anomalous negative magnetoresistance in quantum-dot Josephson junctions\n  with Kondo correlations: The interplay between superconductivity and the Kondo effect has stimulated\nsignificant interest in condensed matter physics. They compete when their\ncritical temperatures are close and can give rise to a quantum phase transition\nthat can mimic Majorana zero modes. Here, we have fabricated and measured\nAl-InSb nanowire quantum dot-Al devices. In the Kondo regime, a supercurrent-\ninduced zero-bias conductance peak emerges. This zero-bias peak shows an\nanomalous negative magnetoresistance (NMR) at weak magnetic fields. We\nattribute this anomalous NMR to quasi- particle trapping at vortices in the\nsuperconductor leads as a weak magnetic field is applied. The trapping effect\nlowers the quasiparticle-caused dissipation and thus enhances the Josephson\ncurrent. This work connects the vortex physics and the supercurrent tunneling\nin Kondo regimes and can help further understand the physics of Josephson\nquantum dot system."
    },
    {
        "anchor": "Comparative Studies on Giant Magnetoresistance in Carbon Nanotubes and\n  Graphene Nanoribbons with Ferromagnetic Contacts: This contribution reports on comparative studies on giant magnetoresistance\n(GMR) in carbon nanotubes (CNTs) and graphene nanoribbons of similar aspect\nratios (i.e perimeter/length and width/length ratios, for the former and the\nlatter, respectively). The problem is solved at zero temperature in the\nballistic transport regime, by means of the Green's functions technique within\nthe tight-binding model and with the so-called wide band approximation for\nelectrodes. The GMR effect in graphene is comparable to that of CNTs, it\ndepends strongly on the chirality and only slightly on the aspect ratio. It\nturns out that graphene, analogously to CNTs may be quite an interesting\nmaterial for spintronic applications.",
        "positive": "Diffusivity Reveals Three Distinct Phases of Interlayer Excitons in\n  MoSe2/WSe2 Heterobilayers: Charge separated interlayer excitons in transition metal dichalcogenide\n(TMDC) heterobilayers are being explored for moir\\'e exciton lattices and\nexciton condensates. The presence of permanent dipole moments and the poorly\nscreened Coulomb interaction make many body interactions particularly strong\nfor interlayer excitons. Here we reveal two distinct phase transitions for\ninterlayer excitons in the MoSe2/WSe2 heterobilayer using time and spatially\nresolved photoluminescence imaging: from trapped excitons in the\nmoir\\'e-potential to the modestly mobile exciton gas as exciton density\nincreases to ne/h ~ 1011 cm-2 and from the exciton gas to the highly mobile\ncharge separated electron/hole plasma for ne/h > 1012 cm-2. The latter is the\nMott transition and is confirmed in photoconductivity measurements. These\nfindings set fundamental limits for achieving quantum states of interlayer\nexcitons."
    },
    {
        "anchor": "4D spinless topological insulator in a periodic electric circuit: According to the mathematical classification of topological band structures,\nthere exist a number of fascinating topological states in dimensions larger\nthan three with exotic boundary phenomena and interesting topological\nresponses. While these topological states are not accessible in condensed\nmatter systems, recent works have shown that synthetic systems, such as\nphotonic crystals or electric circuits, can realize higher-dimensional band\nstructures. Here, we argue that the 4D spinless topological insulator, due to\nits symmetry properties, is particularly well suited to be implemented in these\nsynthetic systems. We explicitly construct a 2D electric circuit lattice, whose\nresonance frequency spectrum simulate the 4D spinless topological insulator. We\nperform detailed numerical calculations of the circuit lattice and show that\nthe resonance frequency spectrum exhibit pairs of 3D Weyl boundary states, a\nhallmark of the nontrivial topology. These pairs of 3D Weyl states with the\nsame chirality are protected by classical time-reversal symmetry that squares\nto $+1$, which is inherent in the proposed circuit lattice. We also discuss how\nthe simulated 4D topological band structure can be observed in experiments.",
        "positive": "Revisiting (higher order and crystalline) topology in old models of lead\n  telluride: In this work, we revisit the model of PbTe presented in [E. Fradkin, E.\nDagotto, and D. Boyanovsky, Phys. Rev. Lett. 57, 2967 (1986)]. We show that the\nlow energy theory of this model corresponds to a (higher-order) topological\ncrystalline insulator in space group $Fm\\bar{3}m1'$, diagnosable by symmetry\nindicators. We show that the gapless fermions found on antiphase domain walls\nare the topological boundary modes of the system, due to a nonvanishing mirror\nChern number. Furthermore, we show that any symmetric completion of the model\nmust be in this same topological phase. Finally, we comment on the relationship\nof this model to realistic PbTe, which has recently been predicted to have a\nphase which realizes same bulk symmetry indicators."
    },
    {
        "anchor": "Determination of Intrinsic Effective Fields and Microwave Polarizations\n  by High-Resolution Spectroscopy of Single NV Center Spins: We present high-resolution optically detected magnetic resonance (ODMR)\nspectroscopy on single nitrogen-vacancy (NV) center spins in diamond at and\naround zero magnetic field. The experimentally observed transitions depend\nsensitively on the interplay between the microwave (MW) probing field and the\nlocal intrinsic effective field comprising strain and electric fields, which\nact on the NV spin. Based on a theoretical model of the magnetic dipole\ntransitions and the MW driving field, we extract both the strength and the\ndirection of the transverse component of the effective field. Our results\nreveal that for the diamond crystal under study, strain is the dominant\ncontribution to the effective field. Our experiments further yield a method for\nMW polarization analysis in a tunable, linear basis, which we demonstrate on a\nsingle NV spin. Our results are of importance to low-field quantum sensing\napplications using NV spins and form a relevant addition to the ever-growing\ntoolset of spin-based quantum sensing.",
        "positive": "Metallic Coulomb Blockade Thermometry down to 10 mK and below: We present an improved nuclear refrigerator reaching 0.3 mK, aimed at\nmicrokelvin nanoelectronic experiments, and use it to investigate metallic\nCoulomb blockade thermometers (CBTs) with various resistances R. The high-R\ndevices cool to slightly lower T, consistent with better isolation from the\nnoise environment, and exhibit electron-phonon cooling ~ T^5 and a residual\nheat-leak of 40 aW. In contrast, the low-R CBTs display cooling with a clearly\nweaker T-dependence, deviating from the electronphonon mechanism. The CBTs\nagree excellently with the refrigerator temperature above 20 mK and reach a\nminimum-T of 7.5 +/- 0.2 mK."
    },
    {
        "anchor": "Spin-orbital Kondo effect in a parallel double quantum dot: Transport properties of the two-orbital Kondo effect involving both spin and\norbital (pseudospin) degrees of freedom were examined in a parallel double\nquantum dot with a sufficient interdot Coulomb interaction and negligibly small\ninterdot tunneling. The Kondo effect was observed at the interdot Coulomb\nblockade region with degeneracies of both spin and orbital degrees of freedom.\nWhen the orbital degeneracy is lifted by applying a finite detuning, the Kondo\nresonance exhibits a triple-peak structure, indicating that both spin and\norbital contributions are involved.",
        "positive": "Novel topological phases of a semi-Dirac Chern insulator in presence of\n  extended range hopping: We study topological properties and the topological phase transitions therein\nfor a semi-Dirac Haldane model on a honeycomb lattice in presence of an\nextended range (third neighbour) hopping. While in the absence of a third\nneighbour hopping, $t_3$, the system exhibits gapless electronic spectrum, its\npresence creates an energy gap in the dispersion. However, the nature of the\nspectral gap, that is, whether it is trivial or topological needs to be\nascertained. We find that the answer depends on the value of $t_3$, and its\ninterplay with the value of the onsite potential that breaks the sublattice\nsymmetry, namely, Semenoff mass ($\\Delta$). To elucidate our findings on the\ntopological phases, we demonstrate two kinds of phase diagrams using the\navailable parameter space, one in which the phases are shown in the\n$\\Delta$-$t_3$ plane, and the other one in a more familiar $\\Delta$-$\\phi$\nplane ($\\phi$ being the Haldane flux). The phase diagrams depict the presence\nof Chern insulating lobes comprising of Chern numbers $\\pm2$ and $\\pm1$ for\ncertain values of $t_3$, along with trivial insulating regions (zero Chern\nnumber). Thus there are phase transitions from one topological regime to\nanother which are characterized by abrupt changes in the values of the Chern\nnumber. To support the existence of the topological phases, we compute the\ncounter-propagating chiral edge modes in a ribbon geometry. Finally, the\nanomalous Hall conductivity shows plateaus either at $e^2/h$ or $2e^2/h$\ncorresponding to these topological phases."
    },
    {
        "anchor": "Far-infrared absorption in single-electron transistors: Theoretical\n  results and experiment proposal: We present theoretical results on far-infrared (FIR) absorption of\nsingle-electron transistors. Based on them, we propose and explain how to\nconduct combined FIR--dc-transport experiments to determine the charging energy\nand other relevant parameters, without measuring FIR intensities.",
        "positive": "Topological magnetic dipolar interaction and non-local electric\n  magnetization control in topological insulator heterostructures: The magnetoelectric effect predicted in topological insulators makes\nheterostructures that combine magnetic materials and such insulators promising\ncandidates for spintronics applications. Here, we theoretically consider a\nsetup that exhibits two well-separated interfaces between a topological\ninsulator and a ferromagnetic insulator. We show that there is a topological\nmagnetic dipole-dipole interaction stemming from long-range Coulomb\ninteractions. We analytically derive the magnetization dynamics at the two\ninterfaces and discuss how the long-range coupling can be applied to\nnon-locally induce the formation of a magnetic texture at one interface by\nsuitably gating the other interface."
    },
    {
        "anchor": "Electrical tuning of spin current in a boron nitride nanotube quantum\n  dot: Controlling spin current and magnetic exchange coupling by applying an\nelectric field and achieving high spin injection efficiency at the same time in\na nanostructure coupled to ferromagnetic electrodes have been the outstanding\nchallenges in nanoscale spintronics. A relentless quest is going on to find new\nlow dimensional materials with tunable spin dependent properties to address\nthese challenges. Herein, we predict, from first principles, the transverse\nelectric field induced switching in the sign of exchange coupling and tunnel\nmagnetoresistance in a boron nitride nanotube quantum dot attached to\nferromagnetic nickel contacts.",
        "positive": "Coulomb blockade in field electron emission from carbon nanotubes: We report the observation of Coulomb blockade in field electron emission (FE)\nfrom single-wall carbon nanotubes (SWCNTs), which is manifested as pronounced\nsteps in the FE current-voltage curves and oscillatory variations in the energy\ndistribution of emitted electrons. The appearance of the Coulomb blockade is\nexplained by the formation of nanoscale protrusions at the apexes of SWCNTs due\nto the electric field-assisted surface diffusion of adsorbates and carbon\nadatoms. The proposed adsorbate-assisted FE mechanism is substantially\ndifferent from the well-known resonant tunneling associated with discrete\nelectronic states of adsorbed atoms. The simulations based on the Coulomb\nblockade theory are in excellent agreement with the experimental results. The\nSWCNT field emitters controlled by the Coulomb blockade effect are expected to\nbe used to develop on-demand coherent single-electron sources for advanced\nvacuum nanoelectronic devices."
    },
    {
        "anchor": "Hong-Ou-Mandel heat noise in the quantum Hall regime: We investigate heat current fluctuations induced by a periodic train of\nLorentzian-shaped pulses, carrying an integer number of electronic charges, in\na Hong-Ou-Mandel interferometer implemented in a quantum Hall bar in the\nLaughlin sequence. We demonstrate that the noise in this collisional experiment\ncannot be reproduced in a setup with a single drive, in contrast to what is\nobserved in the charge noise case. Nevertheless, the simultaneous collision of\ntwo identical levitons always leads to a total suppression even for the\nHong-Ou-Mandel heat noise at all filling factors, despite the presence of\nemergent anyonic quasi-particle excitations in the fractional regime.\nInterestingly, the strong correlations characterizing the fractional phase are\nresponsible for a remarkable oscillating pattern in the HOM heat noise, which\nis completely absent in the integer case. These oscillations can be related to\nthe recently predicted crystallization of levitons in the fractional quantum\nHall regime.",
        "positive": "Effects of tunneling and multiphoton transitions on squeezed states\n  generation in bistable driven systems: Bistability of nonlinear resonantly driven oscillator in the presence of\nexternal noise is analyzed by means of classical Fokker-Planck equation in\nquasienergy space with account for tunneling effects and by quantum master\nequation in quasienergy states representation. Two time scales responsible for\ndifferent stages of bistable system relaxation have been obtained. We found out\nthat the slow relaxation rate caused by fluctuation--induced transitions\nbetween different stable states can be enhanced by several orders due to\ntunneling effects. It was also revealed that tunneling between nearly\ndegenerate quasienergy states and resonant multiphoton transitions between the\ngenuine eigenstates of the nonlinear oscillator are just the similar effects.\nIt was demonstrated that the quasienergy states in the bistability region\ncorresponding to higher amplitude are squeezed. The degree of squeezing is\ndetermined by the ratio between nonlinearity and detuning, so the uncertainty\nof one quadrature can be considerably smaller than the quantum limit. It was\nfound out that tunneling effects can enhance the generation of output\noscillator squeezed states. It is shown that 1D Fokker--Planck equation is a\nquasiclassical limit of a quantum master equation."
    },
    {
        "anchor": "Quantum Hall effects in layered disordered superconductors: Layered singlet paired superconductors with disorder and broken time reversal\nsymmetry are studied. The phase diagram demonstrates charge-spin separation in\ntransport. In terms of the average intergrain transmission and the interlayer\ntunnelling we find quantum Hall phases with spin Hall coefficients of 0 and 2\nseparated by a spin metal phase. We identify a spin metal-insulator\nlocalization exponent as well as a spin conductivity exponent of ~0.9. In\npresence of a Zeeman term an additional phase with spin Hall coefficient of 1\nappears.",
        "positive": "Effect of Landau Level Mixing for Electrons in Random Magnetic Field: An effective Hamiltonian approach is used to study the effect of Landau-level\nmixing on the energy spectrum of electrons in a smooth but random magnetic\nfield B(r) with a finite uniform component B_0. It is found that, as opposed to\nelectrostatic disorder, the energy levels of localized electrons shift upward\nwith a rate of order O(1/B_0) when B_0 is decreased, while the extended states\nremain static at the same order. Therefore, there is no indication that the\nextended states will float out of the Fermi energy and induce a metal-insulator\ntransition as the magnetic disorder is increased. We also find that the Zeeman\nterm may have significant effect on the spectral shift of low-lying Landau\nlevels."
    },
    {
        "anchor": "Charge transport in a single superconducting tin nanowire encapsulated\n  in a multiwalled carbon nanotube: The charge transport properties of single superconducting tin nanowires,\nencapsulated by multiwalled carbon nanotubes have been investigated by\nmulti-probe measurements. The multiwalled carbon nanotube protects the tin\nnanowire from oxidation and shape fragmentation and therefore allows us to\ninvestigate the electronic properties of stable wires with diameters as small\nas 25 nm. The transparency of the contact between the Ti/Au electrode and\nnanowire can be tuned by argonion etching the multiwalled nanotube. Application\nof a large electrical current results in local heating at the contact which in\nturn suppresses superconductivity.",
        "positive": "Theory for the negative longitudinal magnetoresistance in the quantum\n  limit of Kramers Weyl semimetals: Negative magnetoresistance is rare in non-magnetic materials. Recently, a\nnegative magnetoresistance has been observed in the quantum limit of\n$\\beta$-Ag$_2$Se, where only one band of Landau levels is occupied in a strong\nmagnetic field parallel to the applied current. $\\beta$-Ag$_2$Se is a material\nthat host a Kramers Weyl cone with band degeneracy near the Fermi energy.\nKramers Weyl cones exist at time-reversal invariant momenta in all symmorphic\nchiral crystals, and at a subset of these momenta, including the $\\Gamma$\npoint, in non-symmorphic chiral crystals. Here, we present a theory for the\nnegative magnetoresistance in the quantum limit of Kramers Weyl semimetals. We\nshow that, although there is a band touching similar to those in Weyl\nsemimetals, negative magnetoresistance can exist without a chiral anomaly. We\nfind that it requires screened Coulomb scattering potentials between electrons\nand impurities, which is naturally the case in $\\beta$-Ag$_2$Se."
    },
    {
        "anchor": "Frequency fluctuations in nanomechanical silicon nitride string\n  resonators: High quality factor ($Q$) nanomechanical resonators have received a lot of\nattention for sensor applications with unprecedented sensitivity. Despite the\nlarge interest, few investigations into the frequency stability of high-$Q$\nresonators have been reported. Such resonators are characterized by a linewidth\nsignificantly smaller than typically employed measurement bandwidths, which is\nthe opposite regime to what is normally considered for sensors. Here, the\nfrequency stability of high-$Q$ silicon nitride string resonators is\ninvestigated both in open-loop and closed-loop configurations. The stability is\nhere characterized using the Allan deviation. For open-loop tracking, it is\nfound that the Allan deviation gets separated into two regimes, one limited by\nthe thermomechanical noise of the resonator and the other by the detection\nnoise of the optical transduction system. The point of transition between the\ntwo regimes is the resonator response time, which can be shown to have a linear\ndependence on $Q$. Laser power fluctuations from the optical readout is found\nto present a fundamental limit to the frequency stability. Finally, for\nclosed-loop measurements, the response time is shown to no longer be\nintrinsically limited but instead given by the bandwidth of the closed-loop\ntracking system. Computed Allan deviations based on theory are given as well\nand found to agree well with the measurements. These results are of importance\nfor the understanding of fundamental limitations of high-$Q$ resonators and\ntheir application as high performance sensors.",
        "positive": "Magnetoconductance Anisotropies and Aharonov-Casher Phases: The spin-orbit interaction is a key tool for manipulating and functionalizing\nspin-dependent electron transport. However, the precise value of the spin-orbit\ncoupling constant is hard to determine and control. Here we propose a\nmeasurement of the geometric (Aharonov-Casher) phase of the electron\nwavefunction generated by the spin-orbit coupling as a means to deduce the\nspin-orbit coupling strength in weak links. Unlike other proposed measurements\nof geometric phases, which rely on interference, we show that the anisotropy of\nthe magnetoconductance, measured at different directions of an external\nmagnetic field,is determined by the geometric phase. Specifically we consider\nweak links in which the Rashba interaction is caused by an external electric\nfield, but our method is expected to apply also for other forms of the\nspin-orbit coupling. Measuring this magnetoconductance anisotropy thus allows\ncalibrating Rashba spintronic devices by an external electric field that tunes\nthe spin-orbit interaction."
    },
    {
        "anchor": "Non-universal power laws in transport properties of one-dimensional\n  quantum dots: We investigate discrepancies between recent experimental results on transport\nthrough one-dimensional quantum dots and universal power laws predicted by an\nidealized Luttinger Liquid description. The temperature dependence of Coulomb\nblockade peaks in one-dimensional quantum dots obeys non-universal power-laws\nfrom which different values of the interaction strength can be deduced. We find\nthat, depending on the temperature range, measurements probe local or global\nproperties of the interaction. In particular, we investigate the role of\ncontacting semiconductor quantum wires and nanotubes connected to leads through\ntunnel junctions and compare to recent experiments. We conclude that a\nconventional Luttinger Liquid description of the quantum wire does explain the\nobserved behaviour if specific properties of either experimental setup are\ncarefully taken into account.",
        "positive": "Cryogenic instrumentation for fast current measurement in a silicon\n  single electron transistor: We present a realisation of high bandwidth instrumentation at cryogenic\ntemperatures and for dilution refrigerator operation that possesses advantages\nover methods using radio-frequency single electron transistor or transimpedance\namplifiers. The ability for the low temperature electronics to carry out faster\nmeasurements than with room temperature electronics is investigated by the use\nof a phosphorous-doped single-electron transistor. A single-shot technique is\nsuccessfully implemented and used to observe the real time decay of a quantum\nstate. A discussion on various measurement strategies is presented and the\nconsequences on electron heating and noise are analysed."
    },
    {
        "anchor": "Low temperature dephasing in irradiated metallic wires: We present phase coherence time measurements in quasi-one-dimensional Ag\nwires implanted with Ag$^{+}$ ions with an energy of $100 keV$. The\nmeasurements have been carried out in the temperature range from $100 mK$ up to\n$10 K$; this has to be compared with the Kondo temperature of iron in silver,\ni.e. $T_{K}^{Ag/Fe} \\approx 4 K$, used in recent experiments on dephasing in\nKondo systems\\cite{mallet_prl_06,birge_prl_06}. We show that the phase\ncoherence time is not affected by the implantation procedure, clearly proving\nthat ion implantation process by itself \\emph{does not lead to any extra\ndephasing} at low temperature.",
        "positive": "Dicke-superradiance in electronic systems coupled to reservoirs: We present theoretical results for superradiance, i.e. the collective\ncoherent decay of a radiating system, in semiconductor structures. An optically\nactive region can become superradiant if a strong magnetic field is applied.\nPumping of electrons and holes at a rate T through coupling to external\n`reservoirs' leads to a novel kind of oscillations with frequency $\\sim\n\\sqrt{T}$.}"
    },
    {
        "anchor": "Spin relaxometry of single nitrogen-vacancy defects in diamond\n  nanocrystals for magnetic noise sensing: We report an experimental study of the longitudinal relaxation time ($T_1$)\nof the electron spin associated with single nitrogen-vacancy (NV) defects\nhosted in nanodiamonds (ND). We first show that $T_1$ decreases over three\norders of magnitude when the ND size is reduced from 100 to 10 nm owing to the\ninteraction of the NV electron spin with a bath of paramagnetic centers lying\non the ND surface. We next tune the magnetic environment by decorating the ND\nsurface with Gd$^{3+}$ ions and observe an efficient $T_{1}$-quenching, which\ndemonstrates magnetic noise sensing with a single electron spin. We estimate a\nsensitivity down to $\\approx 14$ electron spins detected within 10 s, using a\nsingle NV defect hosted in a 10-nm-size ND. These results pave the way towards\n$T_1$-based nanoscale imaging of the spin density in biological samples.",
        "positive": "Interaction of electrons with acoustic phonons in AlN/GaN resonant\n  tunnelling nanostructures at different temperatures: The theory of the interaction of electrons with acoustic phonons in\nmultilayer nitride-based AlN/GaN nanostructures was developed for the first\ntime at $T\\geqslant 0$ using the method of finite-temperature Green's functions\nand Dyson equation. Components of the Hamiltonian describing the system of\nelectrons with acoustic phonons and the magnitudes of the electron spectrum\nshifts due to the electron-phonon interaction were obtained. Dependences of the\nelectronic spectrum levels and spectrum of the acoustic phonons were found\ndepending on the position of the internal potential barrier in the studied\nnanostructure. The temperature shifts of the electronic spectrum and decay\nrates were calculated for various values of temperature $T$."
    },
    {
        "anchor": "Optical characterization of dislocation free Ge and GeOI wafers: Optical properties of dislocations free state-of-the-art Germanium(Ge) and\nGermanium-oninsulator(GeOI) wafers have been characterized using Fourier\ntransformed infrared spectroscopy at oblique incidence, attenuated total\nreflectance, laser Raman scattering, linear and nonlinear optical transmission.\nIn n-type Ge, in addition to vibrational modes observed in intrinsic(i) Ge, a\nband at 535cm-1 which is likely due to carbon and a strong peak at 668 cm-1\nwere observed at non-normal incidence. Despite the strong heavy hole to light\nhole absorption band at low energies, the 668 cm-1 peak was also observed in\np-Ge. The appearance of new bands and the enhancement in band strength are in\ngeneral observed in both type of wafers at oblique incidence. GeOI exhibits a\nstrong disorder induced LO-TO coupling mode which can only be observed at\nnon-normal incidence. Optical absorption at the near bang edge reveals the\npresence of doping related disorder and band shrinkage, which is supported also\nby Ge-Ge one-phonon line broadening at 301 cm-1. Different nonlinear optical\nabsorption behavior was observed in n-Ge, p-Ge and GeOI wafers. The p-Ge\nbecomes transparent to CO2 laser line at 10.6 micrometer, while transmitted\npower decreases in n-Ge with increasing UV-VIS pump power.",
        "positive": "Current control of systems with a Peierls distortion by magnetic field: We study the tunneling phenomenon of a ladder system with a Peierls\ndistortion in a magnetic flux, and the response of electrons the insulator is\ninvestigated when the tunneling current flows on one-dimensional gapped chains\nalong the external electric field. Without the magnetic field, the ladder\nsystem is insulated by the charge density wave order. Then, by the increase of\nthe magnetic field, it becomes metallic with the disappearance of the\ndistortion of the lattice.\n  Finally, the gap appears, and it becomes a insulator.\n  At the metallic state, the topological transition also occurs. To show this\nphenomenon, we consider the distortion by the phonon in the ladder model, and\ncalculate the distortion gap and the transition probability by using both\nLandau-Zener formula and the instanton method. The transition to the metallic\nstates will be applied to the current control by the magnetic field."
    },
    {
        "anchor": "All electrical measurement of the density of states in (Ga,Mn)As: We report on electrical measurements of the effective density of states in\nthe ferromagnetic semiconductor material (Ga,Mn)As. By analyzing the\nconductivity correction due to enhanced electron-electron interaction the\nelectrical diffusion constant was extracted for (Ga,Mn)As samples of different\ndimensionality. Using the Einstein relation allows to deduce the effective\ndensity of states of (Ga,Mn)As at the Fermi energy.",
        "positive": "Self-Quenching of Nuclear Spin Dynamics in Central Spin Problem: We consider, in the framework of the central spin $s=1/2$ model, driven\ndynamics of two electrons in a double quantum dot subject to hyperfine\ninteraction with nuclear spins and spin-orbit coupling. The nuclear subsystem\ndynamically evolves in response to Landau-Zener singlet-triplet transitions of\nthe electronic subsystem controlled by external gate voltages. Without noise\nand spin-orbit coupling, subsequent Landau-Zener transitions die out after\nabout $10^4$ sweeps, the system self-quenches, and nuclear spins reach one of\nthe numerous glassy dark states. We present an analytical model that captures\nthis phenomenon. We also account for the multi-nuclear-specie content of the\ndots and numerically determine the evolution of around $10^7$ nuclear spins in\nup to $2\\times10^5$ Landau-Zener transitions. Without spin-orbit coupling,\nself-quenching is robust and sets in for arbitrary ratios of the nuclear spin\nprecession times and the waiting time between Landau-Zener sweeps as well as\nunder moderate noise. In presence of spin-orbit coupling of a moderate\nmagnitude, and when the waiting time is in resonance with the precession time\nof one of the nuclear species, the dynamical evolution of nuclear polarization\nresults in stroboscopic screening of spin-orbit coupling. However, small\ndeviations from the resonance or strong spin-orbit coupling destroy this\nscreening. We suggest that the success of the feedback loop technique for\nbuilding nuclear gradients is based on the effect of spin-orbit coupling."
    },
    {
        "anchor": "Orbital Kondo effect in a parallel double quantum dot: We construct a theoretical model to study the orbital Kondo effect in a\nparallel double quantum dot (DQD). Recently, pseudospin-resolved transport\nspectroscopy of the orbital Kondo effect in a DQD has been experimentally\nreported. The experiment revealed that when interdot tunneling is ignored,\nthere exist two and one Kondo peaks in the conductance-bias curve for the\npseudospin-non-resolved and pseudospin-resolved cases, respectively. Our\ntheoretical studies reproduce this experimental result. We also investigate the\nsituation of all lead voltages being non-equal (the complete\npseudospin-resolved case), and find that there are four Kondo peaks at most in\nthe curve of the conductance versus the pseudospin splitting energy. When the\ninterdot tunneling is introduced, some new Kondo peaks and dips can emerge.\nBesides, the pseudospin transport and the pseudospin flipping current are also\nstudied in the DQD system. Since the pseudospin transport is much easier to be\ncontrolled and measured than the real spin transport, it can be used to study\nthe physical phenomenon related to the spin transport.",
        "positive": "Cyclopentadienyl-Benzene Based Sandwich Molecular Wires Showing\n  Efficient Spin Filtering, Negative Differential Resistance, and Pressure\n  Induced Electronic Transitions: Using density functional theory, we investigate TM-cyclopentadienyl-benzene\nsandwich molecular wires (SMWs) which are composites of TM-cyclopentadienyl and\nTM-benzene wires (TM = transition metal (V, Fe)). All the SMWs are found to be\nhighly stable ferromagnetic half-metals, showing spin switching behavior.\nTransport calculations show that finite size clusters display spin filter\nproperty when coupled with Au electrodes on either side. I-V characteristics of\nall systems confirm the spin filter property, with Au-BzVCpVBz-Au displaying\nexceptionally high performance. In addition to spin filtering, the\nAu-BzFeCpFeBz-Au system also shows negative differential resistance (NDR).\nCompression causes an abrupt reduction in magnetic moment and a transition to a\nmetallic phase, while stretching causes an increase in magnetic moment.\nHalf-metallicity is preserved for modest amounts of stretching and compression."
    },
    {
        "anchor": "Interplay between phonon and impurity scattering in 2D hole transport: We investigate temperature dependent transport properties of two-dimensional\np-GaAs systems taking into account both hole-phonon and hole-impurity\nscattering effects. By analyzing the hole mobility data of p-GaAs in the\ntemperature range 10 K$<T<$100 K, we estimate the value of the appropriate\ndeformation potential for hole-phonon coupling. Due to the interplay between\nhole-phonon and hole-impurity scattering the calculated temperature-dependent\nresistivity shows interesting nonmonotonic behavior. In particular, we find\nthat there is a temperature range (typically 2 K$<T<$10 K) in which the\ncalculated resistivity becomes independent of temperature due to a subtle\ncancellation between the temperature dependent resistive scattering\ncontributions arising from impurities and phonons. This resistivity saturation\nregime appears at low carrier densities when the increasing resistivity due to\nphonon scattering compensates for the decreasing resistivity due to the\nnondegeneracy effect. This temperature-independent flat resistivity regime is\nexperimentally accessible and may have already been observed in a recent\nexperiment.",
        "positive": "Uniaxial strain-induced Kohn anomaly and electron-phonon coupling in\n  acoustic phonons of graphene: Recent advances in strain engineering at the nanoscale have shown the\nfeasibility to modulate the properties of graphene. Although the\nelectron-phonon (e-ph) coupling and Kohn anomalies in graphene define the\nphonon branches contributing to the resonance Raman scattering, and is relevant\nto the electronic and thermal transport as a scattering source, the evolution\nof the e-ph coupling as a function of strain has been less studied. In this\nwork, the Kohn anomalies and the e-ph coupling in uniaxially strained graphene\nalong armchair (AC) and zigzag (ZZ) directions were studied by means of density\nfunctional perturbation theory calculations. In addition to the phonon anomaly\nat the transversal optical (TO) phonon branch in the K point for pristine\ngraphene, we found that uniaxial strain induces a discontinuity in the\nfrequency derivative of the longitudinal acoustic (LA) phonon branch. This\nbehavior corresponds to the emergence of a Kohn anomaly, as a consequence of a\nstrain-enhanced e-ph coupling. Thus, the present results for uniaxially\nstrained graphene contrast with the commonly assumed view that the e-ph\ncoupling around the K point is only present in the TO phonon branch."
    },
    {
        "anchor": "Toward phonon-boundary engineering in nanoporous materials: Tuning thermal transport in nanostructured materials is a powerful approach\nto develop high-efficiency thermoelectric materials. Using a recently developed\napproach based on the phonon mean free path dependent Boltzmann transport\nequation, we compute the effective thermal conductivity of nanoporous materials\nwith pores of various shapes and arrangements. We assess the importance of\npore-pore distance in suppressing thermal transport, and identify the pore\narrangement that minimizes the thermal conductivity, composed of a periodic\narrangement of two misaligned rows of triangular pores. Such a configuration\nyields a reduction in the thermal conductivity of more than $60 \\%$ with\nrespect the simple circular aligned case with the same porosity.",
        "positive": "Theory of magnetotransport in artificial kagome spin ice: Magnetic nanoarray with special geometries exhibits nontrivial collective\nbehaviors similar to those observed in the spin ice materials. Here we present\na novel circuit model to describe the complex magnetotransport phenomena in\nartificial kagome spin ice. In this picture, the system can be viewed as a\nresistor network driven by voltage sources that are located at vertices of the\nhoneycomb array. The differential voltages across different terminals of these\nsources are related to the ice-rules that govern the local magnetization\nordering. The circuit model relates the transverse Hall voltage of kagome ice\nto the underlying spin correlations. Treating the magnetic nanoarray as\nmetamaterials, we present a mesoscopic constitutive equation relating the Hall\nresistance to magnetization components of the system. We further show that the\nHall signal is significantly enhanced when the kagome ice undergoes a\nmagnetic-charge ordering transition. Our analysis can be readily generalized to\nother lattice geometry, providing a quantitative method for the design of\nmagnetoresistance devices based on artificial spin ices."
    },
    {
        "anchor": "Sideband control of a multimode quantum bulk acoustic system: Multimode bulk acoustic systems show promise for use in superconducting\nquantum computation. They can serve as a medium term memory storage, with\nexceptional coherence times demonstrated, and they exhibit a mode density that\nis physically highly compact. Here we experimentally demonstrate accessing\nindividual acoustic modes without being hindered by the uniform frequency\nspacing of the modes. We use sideband control where a low-frequency modulation\nis applied to the transmon qubit energy. The amplitude of the modulation\ndefines the qubit-acoustic mode coupling, and its frequency detunes the\nacoustic sidebands, therefore enabling selectively switching on or off the\ninteraction, and allows for a full control on the individual modes.",
        "positive": "ZnPSe$_3$ as ultrabright indirect bandgap system with microsecond\n  excitonic lifetimes: We report an optical characterization of ZnPSe$_3$ crystals that demonstrates\nindirect band gap characteristics in combination with unusually strong\nphotoluminescence. We found evidence of interband recombination from excitonic\nstates with microsecond lifetimes. Through optical characterization, we\nreconstructed the electronic band scheme relevant for fundamental processes of\nlight absorption, carrier relaxation and radiative recombination. The\ninvestigation of the radiative processes in the presence of magnetic field\nrevealed spin polarization of fundamental electronic states. This observation\nopens a pathway towards controlling the spin of excitonic states in\ntechnologically relevant microsecond timescales."
    },
    {
        "anchor": "Tilt induced vortical response and mixed anomaly in inhomogeneous Weyl\n  matter: We propose a non-dissipative transport effect and vortical response in Weyl\nsemimetals in the presence of spatial inhomogeneities, namely a spatially\nvarying tilt of the Weyl cones. We show that when the spectrum is anisotropic\nand tilted due to spatial lattice variations, one is confronted with\ngeneralized quantum anomalies due to the effective fields stemming from the\ntilt structure. In particular, we demonstrate that the position-dependent tilt\nparameter induces local vorticity, thus generating a chiral vortical effect\neven in the absence of rotation or magnetic fields. As a consequence, it\ncouples to the electric field and thus contributes to the anomalous Hall\neffect.",
        "positive": "Coulomb Blockade due to Quantum Phase-Slips Illustrated with Devices: In order to illustrate the emergence of Coulomb blockade from coherent\nquantum phase-slip processes in thin superconducting wires, we propose and\ntheoretically investigate two elementary setups, or \"devices\". The setups are\nderived from Cooper-pair box and Cooper-pair transistor, so we refer to them as\nQPS-box and QPS-transistor, respectively. We demonstrate that the devices\nexhibit sensitivity to a charge induced by a gate electrode, this being the\nmain signature of Coulomb blockade. Experimental realization of these devices\nwill unambiguously prove the Coulomb blockade as an effect of coherence of\nphase-slip processes. We analyze the emergence of discrete charging in the\nlimit strong phase-slips. We have found and investigated six distinct regimes\nthat are realized depending on the relation between three characteristic energy\nscales: inductive and charging energy, and phase-slip amplitude. For\ncompleteness, we include a brief discussion of dual Josephson-junction devices."
    },
    {
        "anchor": "Hot carriers in an intrinsic graphene: Heating of carriers in an intrinsic graphene under dc electric field is\nconsidered taking into account the intraband energy relaxation due to acoustic\nphonon scattering and the interband generation-recombination transitions due to\nthermal radiation. The distribution of nonequilibrium carriers is obtained for\nthe cases when the intercarrier scattering is unessential and when the\ncarrier-carrier Coulomb scattering effectively establishes the quasiequilibrium\ndistribution with the temperature and the density of carriers that are\ndetermined by the balance equations. Because of an interplay between weak\nenergy relaxation and generation-recombination processes a very low threshold\nof nonlinear response takes place. The nonlinear current-voltage\ncharacteristics are calculated for the case of the momentum relaxation caused\nby the elastic scattering. Obtained current-voltage characteristics show low\nthreshold of nonlinear behavior and appearance of the second ohmic region, for\nstrong fields.",
        "positive": "Quantum plasmons and intraband excitons in doped nanoparticles: Failure\n  of the Tamm-Dancoff approximation and importance of electron-hole attraction: We use excited-state quantum chemistry techniques to investigate the\nintraband absorption of doped semiconductor nanoparticles as a function of\ndoping density, nanoparticle radius, and material properties. The excess\nelectrons are modeled as interacting particles confined in a sphere. We compare\nthe predictions of various single-excitation theories, including time-dependent\nHartree-Fock, the random-phase approximation, and configuration interaction\nwith single excitations. We find that time-dependent Hartree-Fock most\naccurately describes the character of the excitation, as compared to\nequation-of-motion coupled-cluster theory with single and double excitations.\nThe excitation evolves from confinement-dominated, to excitonic, to plasmonic\nwith increasing number of electrons at fixed density, and the threshold number\nof electrons to produce a plasmon increases with density due to quantum\nconfinement. Exchange integrals (attractive electron-hole interactions) are\nessential to properly describe excitons, and de-excitations (i.e.~avoidance of\nthe Tamm-Dancoff approximation) are essential to properly describe plasmons. We\npropose a schematic model whose analytic solutions closely reproduce our\nnumerical calculations. Our results are in good agreement with experimental\nspectra of doped ZnO nanoparticles at a doping density of $1.4\\times 10^{20}$\ncm$^{-3}$."
    },
    {
        "anchor": "Probing quantum capacitance in a 3D topological insulator: We measure the quantum capacitance and probe thus directly the electronic\ndensity of states of the high mobility, Dirac type of two-dimensional electron\nsystem, which forms on the surface of strained HgTe. Here we show that observed\nmagneto-capacitance oscillations probe, in contrast to magnetotransport,\nprimarily the top surface. Capacitance measurements constitute thus a powerful\ntool to probe only one topological surface and to reconstruct its Landau level\nspectrum for different positions of the Fermi energy.",
        "positive": "Nodal lines and boundary modes in topological Dirac semimetals with\n  magnetism: Nodal-line semimetals with magnetic orders have been theoretically predicted\nand experimentally observed in only few compounds. We theoretically explore the\nelectronic structure in bulk and boundary of such a magnetic nodal-line state\nby introducing magnetism in topological Dirac semimetal (TDSM). TDSMs, such as\n$\\mathrm{Cd_3 As_2}$ and $\\mathrm{Na_3 Bi}$, are characterized by a pair of\nspin-degenerate Dirac points protected by rotational symmetries of crystals. By\nintroducing local magnetic moments coupled to the electron spins in the lattice\nmodel of TDSM, we show that the TDSM can turn into either a Weyl semimetal or a\nnodal-line semimetal, which is determined by the orbital dependence in the\nexchange coupling and the direction of magnetization formed by the magnetic\nmoments. In this magnetic nodal-line semimetal state, we find zero modes with\ndrumhead-like band structure at the boundary that are characterized by the\ntopological number of $\\mathbb{Z}$. Those zero modes are numerically\ndemonstrated by introducing magnetic domain walls in the lattice model."
    },
    {
        "anchor": "Bound states in the continuum driven by AC fields: We report the formation of bound states in the continuum driven by AC fields.\nThis system consists of a quantum ring connected to two leads. An AC side-gate\nvoltage controls the interference pattern of the electrons passing through the\nsystem. We model the system by two sites in parallel connected to two\nsemi-infinite lattices. The energy of these sites change harmonically with\ntime. We obtain the transmission probability and the local density of states at\nthe ring sites as a function of the parameters that define the system. The\ntransmission probability displays a Fano profile when the energy of the\nincoming electron matches the driving frequency. Correspondingly, the local\ndensity of states presents a narrow peak that approaches a Dirac delta function\nin the weak coupling limit. We attribute these features to the presence of\nbound states in the continuum.",
        "positive": "Spin-selective optical absorption of singly charged excitons in a\n  quantum dot: We investigate high resolution laser absorption spectroscopy of a single\nInGaAs/GaAs self-assembled quantum dot embedded in a field-effect structure. We\nshow experimentally that the interband optical absorption to the lower Zeeman\nbranch of the singly charged exciton is strongly inhibited due to spin (Pauli)\nblockade of the optical transition. At high magnetic fields the optical\nabsorption to the upper Zeeman branch dominates the absorption spectrum. We\nfind however that the spin blockade is not complete and a 10% leakage remains\nat high magnetic fields. Applying a gate voltage to empty the dot of its\nresident electron turns off the spin blockade. This effect is observed at 1.5 K\nand up to 9 Tesla."
    },
    {
        "anchor": "Single-photon nonlinear optics with graphene plasmons: We show that it is possible to realize significant nonlinear optical\ninteractions at the few photon level in graphene nanostructures. Our approach\ntakes advantage of the electric field enhancement associated with the strong\nconfinement of graphene plasmons and the large intrinsic nonlinearity of\ngraphene. Such a system could provide a powerful platform for quantum nonlinear\noptical control of light. As an example, we consider an integrated optical\ndevice that exploits this large nonlinearity to realize a single photon switch.",
        "positive": "Observation of degenerate zero-energy topological states at\n  disclinations in an acoustic lattice: Building upon the bulk-boundary correspondence in topological phases of\nmatter, disclinations have recently been harnessed to trap fractionally\nquantized density of states (DoS) in classical wave systems. While these\nfractional DoS have associated states localized to the disclination's core,\nsuch states are not protected from deconfinement due to the breaking of chiral\nsymmetry, generally leading to resonances which, even in principle, have finite\nlifetimes and suboptimal confinement. Here, we devise and experimentally\nvalidate in acoustic lattices a paradigm by which topological states bind to\ndisclinations without a fractional DoS but which preserve chiral symmetry. The\npreservation of chiral symmetry pins the states at the mid-gap, resulting in\ntheir protected maximal confinement. The integer DoS at the defect results in\ntwo-fold degenerate states that, due to symmetry constraints, do not gap out.\nOur study provides a fresh perspective on the interplay between\nsymmetry-protection in topological phases and topological defects, with\npossible applications in classical and quantum systems alike."
    },
    {
        "anchor": "Enhanced architectures for room-temperature reversible logic gates in\n  graphene: We show that reversible two- and three-input logic gates, among which we\nmention the universal Toffoli gate, can be implemented with three tilted gating\nelectrodes patterned on a monolayer graphene flake. These low-dissipation gates\nare based on the unique properties of ballistic charge carriers in graphene,\nwhich induce the appearance of bandgaps in transmission for properly potential\nbarriers. The enhanced architectures for reversible logic gate implementations\nproposed in this paper offer a remarkable design simplification in comparison\nto standard approaches based on field-effect transistor circuits and a\npotential high-frequency operation.",
        "positive": "Unconventional Features in the Quantum Hall Regime of Disordered\n  Graphene: Percolating Impurity States and Hall Conductance Quantization: We report on the formation of critical states in disordered graphene, at the\norigin of variable and unconventional transport properties in the quantum Hall\nregime, such as a zero-energy Hall conductance plateau in the absence of an\nenergy bandgap and Landau level degeneracy breaking. By using efficient\nreal-space transport methodologies, we compute both the dissipative and Hall\nconductivities of large size graphene sheets with random distribution of model\nsingle and double vacancies. By analyzing the scaling of transport coefficients\nwith defect density, system size and magnetic length, we elucidate the origin\nof anomalous quantum Hall features as magnetic-field dependent impurity states,\nwhich percolate at some critical energies. These findings shed light on\nunidentified states and quantum transport anomalies reported experimentally."
    },
    {
        "anchor": "Conductivity of graphene: How to distinguish between samples with short\n  and long range scatterers: Applying a quasiclassical equation to carriers in graphene we found a way how\nto distinguish between samples with the domination of short and long range\nscatterers from the conductivity measurements. The model proposed explains\nrecent transport experiments with chemically doped as well as suspended\ngraphene.",
        "positive": "Datta-Das transistor for atomtronic circuits using artificial gauge\n  fields: Spin-dependent electrical injection has found useful applications in storage\ndevices, but fully operational spin-dependent semiconductor electronics remain\na challenging task because of weak spin-orbit couplings and/or strong spin\nrelaxations. These limitations are lifted considering atoms instead of\nelectrons or holes as spin carriers. In this emerging field of atomtronics, we\ndemonstrate the equivalent of a Datta-Das transistor using a degenerate Fermi\ngas of strontium atoms as spin carriers in interaction with a tripod\nlaser-beams scheme. We explore the dependence of spin rotation, and we identify\ntwo key control parameters which we interpret as equivalent to the gate-source\nand drain-source voltages of a field effect transistor. Our finding broadens\nthe spectrum of atomtronics devices for implementation of operational\nspin-sensitive circuits."
    },
    {
        "anchor": "Electrically-driven vibronic spectroscopy with sub-molecular resolution: A scanning tunneling microscope is used to generate the electroluminescence\nof phthalocyanine molecules deposited on NaCl/Ag(111). Photon spectra reveal an\nintense emission line at 1.9 eV that corresponds to the fluorescence of the\nmolecules, and a series of weaker red-shifted lines. Based on a comparison with\nRaman spectra acquired on macroscopic molecular crystals, these spectroscopic\nfeatures can be associated to the vibrational modes of the molecules and\nprovide a detailed chemical fingerprint of the probed species. Maps of the\nvibronic features reveal sub- molecularly-resolved structures whose patterns\nare related to the symmetry of the probed vibrational modes.",
        "positive": "Electronic transmission of a nanowire partly irradiated under terahertz\n  electromagnetic field: We theoretically study the electronic transport of a nanowire partly\nirradiated under an external terahertz (THz) electromagnetic field. Although\nthe electrons in the ballistic nanowires only suffer lateral collision with\nphotons the reflection of electrons also takes place in this partly irradiated\ncase. Using free-electron model and scattering matrix approach we showed that\nat resonance there exists a step decrement of 50 percent for the transmission\nprobability as the amplitude of field increases to a certain volume. And the\ncoherent structure of transmission for the system apparently appears when the\nfield irradiate the middle part of nanowire only. This sensitive transmission\nproperty of the system may be used in the THz detection."
    },
    {
        "anchor": "Quantum engineering with hybrid magnonics systems and materials: Quantum technology has made tremendous strides over the past two decades with\nremarkable advances in materials engineering, circuit design and dynamic\noperation. In particular, the integration of different quantum modules has\nbenefited from hybrid quantum systems, which provide an important pathway for\nharnessing the different natural advantages of complementary quantum systems\nand for engineering new functionalities. This review focuses on the current\nfrontiers with respect to utilizing magnetic excitatons or magnons for novel\nquantum functionality. Magnons are the fundamental excitations of magnetically\nordered solid-state materials and provide great tunability and flexibility for\ninteracting with various quantum modules for integration in diverse quantum\nsystems. The concomitant rich variety of physics and material selections enable\nexploration of novel quantum phenomena in materials science and engineering. In\naddition, the relative ease of generating strong coupling and forming hybrid\ndynamic systems with other excitations makes hybrid magnonics a unique platform\nfor quantum engineering. We start our discussion with circuit-based hybrid\nmagnonic systems, which are coupled with microwave photons and acoustic\nphonons. Subsequently, we are focusing on the recent progress of magnon-magnon\ncoupling within confined magnetic systems. Next we highlight new opportunities\nfor understanding the interactions between magnons and nitrogen-vacancy centers\nfor quantum sensing and implementing quantum interconnects. Lastly, we focus on\nthe spin excitations and magnon spectra of novel quantum materials investigated\nwith advanced optical characterization.",
        "positive": "The Non-Dissipative Spin-Hall Current: A theory based on the Aharonov -Bohm effect in the momentum space for the\nSpin-Hall conductivity without a magnetic field is presented. The two\ndimensional Rashba Hamiltonian is diagonalized in the momentum spinor basis.\nThis spinor is singular at K=0. The representation of the cartesian coordinates\nin the spinor momentum basis obey non-commutative rules. The non-commuting\nrelations are a result of an effective Aharonov-Bohm vortex at K=0. We find the\nexact value of $\\frac{e}{4\\pi}$ for the Spin-Hall conductivity. The effect of a\ntime reversal scattering potential on the Spin-Hall current causes the current\nto vanishes for an infinite system."
    },
    {
        "anchor": "Electric field induced injection and shift currents in zigzag graphene\n  nanoribbons: We theoretically investigate the one-color injection currents and shift\ncurrents in zigzag graphene nanoribbons with applying a static electric field\nacross the ribbon, which breaks the inversion symmetry to generate nonzero\nsecond order optical responses by dipole interaction. These two types of\ncurrents can be separately excited by specific light polarization, circularly\npolarized lights for injection currents and linearly polarized lights for shift\ncurrents. Based on a tight binding model formed by carbon 2p$_z$ orbitals, we\nnumerically calculate the spectra of injection coefficients and shift\nconductivities, as well as their dependence on the static field strength and\nribbon width. The spectra show many peaks associated with the optical\ntransition between different subbands, and the positions and amplitudes of\nthese peaks can be effectively controlled by the static electric field. By\nconstructing a simple two band model, the static electric fields are found to\nmodify the edge states in a nonperturbative way, and their associated optical\ntransitions dominate the current generation at low photon energies. For typical\nparameters, such as a static field 10$^6$ V/m and light intensity 0.1\nGW/cm$^2$, the magnitude of the injection and shift currents for a ribbon with\nwidth 5 nm can be as large as the order of 1 $\\mu$A. Our results provide a\nphysical basis for realizing passive optoelectronic devices based on graphene\nnanoribbons.",
        "positive": "Ballistic transport in graphene antidot lattices: Graphene samples can have a very high carrier mobility if influences from the\nsubstrate and the environment are minimized. Embedding a graphene sheet into a\nheterostructure with hexagonal boron nitride (hBN) on both sides was shown to\nbe a particularly efficient way of achieving a high bulk mobility.\nNanopatterning graphene can add extra damage and drastically reduce sample\nmobility by edge disorder. Preparing etched graphene nanostructures on top of\nan hBN substrate instead of SiO2 is no remedy, as transport characteristics are\nstill dominated by edge roughness. Here we show that etching fully encapsulated\ngraphene on the nanoscale is more gentle and the high mobility can be\npreserved. To this end, we prepared graphene antidot lattices where we observe\nmagnetotransport features stemming from ballistic transport. Due to the short\nlattice period in our samples we can also explore the boundary between the\nclassical and the quantum transport regime."
    },
    {
        "anchor": "Voltage Controlled Magnetic Skyrmion Motion for Racetrack Memory: Magnetic skyrmion, vortex-like swirling topologically stable spin\nconfigurations, is appealing as information carrier for future nanoelectronics,\nowing to the stability, small size and extremely low driving current density.\nOne of the most promising applications of skyrmion is to build racetrack memory\n(RM). Compared to domain wall-based RM (DW-RM), skyrmion-based RM (Sky-RM)\npossesses quite a few benefits in terms of energy, density and speed etc. Until\nnow, the fundamental behaviors, including nucleation/annihilation, motion and\ndetection of skyrmion have been intensively investigated. However, one\nindispensable function, i.e., pinning/depinning of skyrmion still remains an\nopen question and has to be addressed before applying skyrmion for RM.\nFurthermore, Current research mainly focuses on physical investigations,\nwhereas the electrical design and evaluation are still lacking. In this work,\nwe aim to promote the development of Sky-RM from fundamental physics to\nrealistic electronics. First, we investigate the pinning/depinning\ncharacteristics of skyrmion in a nanotrack with the voltage-controlled magnetic\nanisotropy (VCMA) effect. Then, we propose a compact model and design framework\nof Sky-RM for electrical evaluation. This work completes the elementary memory\nfunctionality of Sky-RM and fills the technical gap between the physicists and\nelectronic engineers, making a significant step forward for the development of\nSky-RM.",
        "positive": "Spin readout via spin-to-charge conversion in bulk diamond\n  nitrogen-vacancy ensembles: We demonstrate optical readout of ensembles of nitrogen-vacancy(NV) center\nspins in a bulk diamond sample via spin-to-charge conversion. A high power 594\nnm laser is utilized to selectively ionize these paramagnetic defects in the\nspin state with a contrast of up to 12%. In comparison with the conventional\n520 nm spin readout, spin-to-charge-conversion-based readout provides higher\nsignal-to-noise ratio, with tenfold sensing measurement speedup for millisecond\nlong pulse sequences. This level of performance was achieved for an NV-\nionization of only 25%, limited by the ionization and readout laser powers.\nThese observations pave the way to a range of high-sensitivity metrology\napplications where the use of NV- ensembles in bulk diamond has proven useful,\nincluding sensing and imaging of target materials overlaid on the diamond\nsurface."
    },
    {
        "anchor": "Josephson effect in topological superconducting rings coupled to a\n  microwave cavity: We theoretically study a one dimensional p-wave superconducting mesoscopic\nring interrupted by a weak link and coupled inductively to a microwave cavity.\nWe establish an input-output description for the cavity field in the presence\nof the ring, and identify the electronic contributions to the cavity response\nand their dependence on various parameters, such as the magnetic flux, chemical\npotential, and cavity frequency. We show that the cavity response is $4\\pi$\nperiodic as a function of the magnetic flux in the topological region, stemming\nfrom the so called fractional Josephson current carried by the Majorana\nfermions, while it is $2\\pi$ periodic in the non-topological phase, consistent\nwith the normal Josephson effect. We find a strong dependence of the signal on\nthe cavity frequency, as well as on the parity of the ground state. Our model\ntakes into account fully the interplay between the low-energy Majorana modes\nand the gaped bulks states, which we show is crucial for visualizing the\nevolution of the Josephson effect during the transition from the topological to\nthe trivial phase.",
        "positive": "A Nanoscale Experiment Measuring Gravity's Role in Breaking the\n  Unitarity of Quantum Dynamics: Modern, state of the art nanomechanical devices are capable of creating\nspatial superpositions that are massive enough to begin to experimentally\naccess the quantum to classical crossover, and thus force us to consider the\npossible ways in which the usual quantum dynamics may be affected. One recent\ntheoretical proposal describes the crossover from unitary quantum mechanics to\nclassical dynamics as a form of spontaneous symmetry breaking. Here, we propose\na specific experimental setup capable of identifying the source of unitarity\nbreaking in such a mechanism. The experiment is aimed specifically at\nclarifying the role played by gravity, and distinguishes the resulting dynamics\nfrom that suggested by alternative scenarios for the quantum to classical\ncrossover. We give both a theoretical description of the expected dynamics, and\na discussion of the involved experimental parameter values and the proposed\nexperimental protocol."
    },
    {
        "anchor": "Ab-initio transport fingerprints for resonant scattering in graphene: We have recently shown that by using a scaling approach for randomly\ndistributed topological defects in graphene, reliable estimates for\ntransmission properties of macroscopic samples can be calculated based even on\nsingle-defect calculations [A. Uppstu et al., Phys. Rev. B 85, 041401 (2012)].\nWe now extend this approach of energy-dependent scattering cross sections to\nthe case of adsorbates on graphene by studying hydrogen and carbon adatoms as\nwell as epoxide and hydroxyl groups. We show that a qualitative understanding\nof resonant scattering can be gained through density functional theory results\nfor a single-defect system, providing a transmission \"fingerprint\"\ncharacterizing each adsorbate type. This information can be used to reliably\npredict the elastic mean free path for moderate defect densities directly using\nab-initio methods. We present tight-binding parameters for carbon and epoxide\nadsorbates, obtained to match the density-functional theory based scattering\ncross sections.",
        "positive": "Nanomechanical damping via electron-assisted relaxation of two-level\n  systems: We report on measurements of dissipation and frequency noise at millikelvin\ntemperatures of nanomechanical devices covered with aluminum. A clear excess\ndamping is observed after switching the metallic layer from superconducting to\nthe normal state with a magnetic field. Beyond the standard model of internal\ntunneling systems coupled to the phonon bath, here we consider the relaxation\nto the conduction electrons together with the nature of the mechanical\ndispersion laws for stressed/unstressed devices. With these key ingredients, a\nmodel describing the relaxation of two-level systems inside the structure due\nto interactions with electrons and phonons with well separated timescales\ncaptures the data. In addition, we measure an excess 1/f-type frequency noise\nin the normal state, which further emphasizes the impact of conduction\nelectrons."
    },
    {
        "anchor": "Two-Dimensional Electron Gas with Cold Atoms in Non-Abelian Gauge\n  Potentials: Motivated by the possibility of creating non-Abelian fields using cold atoms\nin optical lattices, we explore the richness and complexity of non-interacting\ntwo-dimensional electron gases (2DEGs) in a lattice, subjected to such fields.\nIn the continuum limit, a non-Abelian system characterized by a two-component\n\"magnetic flux\" describes a harmonic oscillator existing in two different\ncharge states (mimicking a particle-hole pair) where the coupling between the\nstates is determined by the non-Abelian parameter, namely the difference\nbetween the two components of the \"magnetic flux.\" A key feature of the\nnon-Abelian system is a splitting of the Landau energy levels, which broaden\ninto bands, as the spectrum depends explicitly on the transverse momentum.\nThese Landau bands result in a coarse-grained \"moth,\" a continuum version of\nthe generalized Hofstadter butterfly. Furthermore, the bands overlap, leading\nto effective relativistic effects. Importantly, similar features also\ncharacterize the corresponding two-dimensional lattice problem when at least\none of the components of the magnetic flux is an irrational number. The lattice\nsystem with two competing \"magnetic fluxes\" penetrating the unit cell provides\na rich environment in which to study localization phenomena. Some unique\naspects of the transport properties of the non-Abelian system are the\npossibility of inducing localization by varying the quasimomentum, and the\nabsence of localization of certain zero-energy states exhibiting a linear\nenergy-momentum relation. Furthermore, non-Abelian systems provide an\ninteresting localization scenario where the localization transition is\naccompanied by a transition from relativistic to non-relativistic theory.",
        "positive": "Theory of Fano resonance in single molecule electroluminescence induced\n  by a scanning tunneling microscope: The coupling between molecular exciton and gap plasmons plays a key role in\nsingle molecular electroluminescence induced by a scanning tunneling microscope\n(STM). But it has been difficult to clarify the complex experimental phenomena.\nBy employing the nonequilibrium Green's function method, we propose a general\ntheoretical model to understand the light emission spectrum from single\nmolecule and gap plasmons from an energy transport point of view. The coherent\ninteraction between gap plasmons and molecular exciton leads to a prominent\nFano resonance in the emission spectrum. We analyze the dependence of the Fano\nline shape on the system parameters, based on which we provide a unified\naccount of several recent experimental observations. Moreover, we highlight the\neffect of the tip-molecule electronic coupling on the spectrum, which has\nhitherto not been considered."
    },
    {
        "anchor": "The Electrochemical Carbon Nanotube Field-Effect Transistor: We explore the electric-field effect of carbon nanotubes (NTs) in\nelectrolytes. Due to the large gate capacitance, Fermi energy shifts of order\n+/- 1 V can be induced, enabling to tune NTs from p to n-type. Consequently,\nlarge resistance changes are measured. At zero gate voltage the NTs are hole\ndoped in air with E_F ? 0.3-0.5 eV, corresponding to a doping level of ?\n10^{13} cm^{-2}. Hole-doping increases in the electrolyte. This hole doping\n(oxidation) is most likely caused by the adsorption of oxygen in air and\ncations in the electrolyte.",
        "positive": "Photon-assisted transport in bilayer graphene flakes: The electronic conductance of graphene-based bilayer flake systems reveal\ndifferent quantum interference effects, such as Fabry-P\\'erot resonances and\nsharp Fano antiresonances on account of competing electronic paths through the\ndevice. These properties may be exploited to obtain spin-polarized currents\nwhen the same nanostructure is deposited above a ferromagnetic insulator. Here\nwe study how the spin-dependent conductance is affected when a time-dependent\ngate potential is applied to the bilayer flake. Following a Tien-Gordon\nformalism we explore how to modulate the transport properties of such systems\nvia appropriate choices of the $ac$-field gate parameters. The presence of the\noscillating field opens the possibility of tuning the original antiresonances\nfor a large set of field parameters. We show that interference patterns can be\npartially or fully removed by the time-dependent gate voltage. The results are\nreflected in the corresponding weighted spin polarization which can reach\nmaximum values for a given spin component. We found that differential\nconductance maps as functions of bias and gate potentials show interference\npatterns for different $ac$-field parameter configurations. The proposed\nbilayer graphene flake systems may be used as a frequency detector in the THz\nrange."
    },
    {
        "anchor": "Comment on ``Magnetic-Field Enhancement of Superconductivity in\n  Ultranarrow Wires'': The authors of a recent Letter [Phys. Rev. Lett. 97, 137001 (2006)] observed\nenhancement of the critical supercurrent of superconducting nanowires in\nexternal magnetic field. They attributed the obtained behavior to the presence\nof magnetic moments in the samples. In this Comment we derive the conditions,\ncrucial for the existence of the observed behavior, and show that they explain\nthe key features of the experiment analytically.",
        "positive": "$N$-band Hopf insulator: We study the generalization of the three-dimensional two-band Hopf insulator\nto the case of many bands, where all the bands are separated from each other by\nband gaps. The obtained $\\mathbb{Z}$ classification of such a $N$-band Hopf\ninsulator is related to the quantized isotropic magnetoelectric coefficient of\nits bulk. The boundary of a $N$-band Hopf insulator can be fully gapped, and we\nfind that there is no unique way of dividing a finite system into bulk and\nboundary. Despite this non-uniqueness, we find that the magnetoelectric\ncoefficient of the bulk and the anomalous Hall conductivity of the boundary are\nquantized to the same integer value. We propose an experiment where the\nquantized boundary effect can be measured in a non-equilibrium state."
    },
    {
        "anchor": "Exciton dynamics and non-linearities in 2D-hybrid organic perovskites: Due to their high potentiality for photovoltaic applications or coherent\nlight sources, a renewed interest in hybrid organic perovskites has emerged for\nfew years. When they are arranged in two dimensions, these materials can be\nconsidered as hybrids quantum wells. One consequence of the unique structure of\n2D hybrid organic perovskites is a huge exciton binding energy that can be\ntailored through chemical engineering. We present experimental investigations\nof the exciton nonlinearities by means of femtosecond pump-probe spectroscopy.\nThe exciton dynamics is fitted with a bi-exponential decay with a free exciton\nlife-time of ~100 ps. Moreover, an ultrafast intraband relaxation (< 150 fs) is\nalso reported. Finally, the transient modification of the excitonic line is\nanalysed through the momenta analysis and described in terms of reduction of\nthe oscillator strength and linewidth broadening. We show that excitonic\nnon-linearities in 2D hybrid organic perovskites share some behaviours of\ninorganic semiconductors despite their huge exciton binding energy.",
        "positive": "Turning chiral skyrmion inside out: The stability of two-dimensional chiral skyrmions in a tilted magnetic field\nis studied. It is shown that by changing the direction of the field and its\nmagnitude, one can continuously transform chiral skyrmion into a skyrmion with\nopposite polarity and vorticity. This turned inside out skyrmion can be\nconsidered as an antiparticle for ordinary axisymmetric skyrmion. For any tilt\nangle of the magnetic field, there is a range of its absolute values where two\ntypes of skyrmions may coexist. In a tilted field, the potentials for\ninter-skyrmion interactions are characterized by the presence of local minima\nsuggesting attractive interaction between the particles. The potentials of\ninter-particle interactions also have so-called fusion channels allowing either\nannihilation of two particles or the emergence of a new particle. The presented\nresults are general for a wide class of magnetic crystals with both easy-plane\nand easy-axis anisotropy."
    },
    {
        "anchor": "Distinguishing coherent from incoherent charge transport in linear\n  triple quantum dots: A fundamental question in quantum transport is how quantum coherence\ninfluences charge transfer through nanostructures. We address this issue for\nlinear triple quantum dots by comparison of a Lindblad density matrix\ndescription with a Pauli rate equation approach and analyze the corresponding\nzero-frequency counting statistics for coherent and sequential charge\ntunneling, respectively. The impact of decaying coherences of the density\nmatrix due to dephasing is also studied. Our findings reveal that the\nsensitivity to coherence shown by shot noise and skewness, in particular in the\nlimit of large coupling to the drain reservoir, can be used to unambiguously\nevidence coherent processes involved in charge transport across triple quantum\ndots. Our analytical results are obtained by using the characteristic\npolynomial approach to full counting statistics.",
        "positive": "Coherence and Screening in Multi-Electron Spin Qubits: The performance of multi-electron spin qubits is examined by comparing\nexchange oscillations in coupled single-electron and multi-electron quantum\ndots in the same device. Fast (> 1 GHz) exchange oscillations with a quality\nfactor Q > 15 are found for the multi-electron case, compared to Q ~ 2 for the\nsingle-electron case, the latter consistent with previous experiments. A model\nof dephasing that includes voltage and hyperfine noise is developed that is in\ngood agreement with both single- and multi-electron data, though in both cases\nadditional exchange-independent dephasing is needed to obtain quantitative\nagreement across a broad parameter range."
    },
    {
        "anchor": "Superconducting SET with tunable electromagnetic environment: We have studied the environmental effect on superconducting single-electron\ntransistors (S-SETs) by biasing S-SETs with arrays of small-capacitance dc\nSQUIDs, whose effective impedance can be varied in situ. As the zero-bias\nresistance of the arrays is increased, Coulomb blockade in the S-SET becomes\nsharper, and the gate-voltage dependence changes from e-periodic to\n2e-periodic. The SQUID arrays could be used as on-chip noise filters.",
        "positive": "The Librator: A new dynamical regime for nonlinear\n  microelectromechanical devices: We present a novel mode of operation for Duffing-type nonlinear\nmicroelectromechanical (MEMS) devices whereby a self-sustained multi-frequency\noutput is generated. This new librator regime creates a limit cycle around a\ndynamical fixed point, i.e. around fixed points within the rotating frame,\nwhereas a traditional oscillator generates a limit cycle around a static fixed\npoint. The librator limit cycles thus created do not change the global topology\nof the rotating frame phase space, but are constrained by it. Due to the\nDuffing nonlinearity different types of limit cycles may be generated within\nthe same phase space, with each type possessing distinct dynamical features.\nTransitioning between these limit cycles requires crossing homoclinic\nbifurcations, which is done without generating chaos as the phase space\ndynamics are two dimensional. This work opens the possibility to the creation\nof a librator network in analogy with oscillator network, however this can be\ndone in a single MEMS device."
    },
    {
        "anchor": "Emergent Momentum-Space Skyrmion Texture on the Surface of Topological\n  Insulators: The quantum anomalous Hall effect has been theoretically predicted and\nexperimentally verified in magnetic topological insulators. In addition, the\nsurface states of these materials exhibit a hedgehog-like \"spin\" texture in\nmomentum space. Here, we apply the previously formulated low-energy model for\nBi$_2$Se$_3$, a parent compound for magnetic topological insulators, to a slab\ngeometry in which an exchange field acts only within one of the surface layers.\nIn this sample set up, the hedgehog transforms into a skyrmion texture beyond a\ncritical exchange field. This critical field marks a transition between two\ntopologically distinct phases. The topological phase transition takes place\nwithout energy gap closing at the Fermi level and leaves the transverse Hall\nconductance unchanged and quantized to $e^2/2h$. The momentum-space skyrmion\ntexture persists in a finite field range. It may find its realization in hybrid\nheterostructures with an interface between a three-dimensional topological\ninsulator and a ferromagnetic insulator.",
        "positive": "Effect of tunneling on the electrical conductivity of nanowire-based\n  films: computer simulation within a core--shell model: We have studied the electrical conductivity of two-dimensional nanowire\nnetworks. An analytical evaluation of the contribution of tunneling to their\nelectrical conductivity suggests that it is proportional to the square of the\nwire concentration. Using computer simulation, three kinds of resistance were\ntaken into account, viz., (i) the resistance of the wires, (ii) the wire---wire\njunction resistance, and (iii) the tunnel resistance between wires. We found\nthat the percolation threshold decreased due to tunneling. However, tunneling\nhad negligible effect on the electrical conductance of dense nanowire networks."
    },
    {
        "anchor": "Ultra-high-ohmic microstripline resistors for Coulomb blockade devices: In this paper, we report on the fabrication and the low-temperature\ncharacterization of extremely high-ohmic microstrip resistors made of a thin\nfilm of weakly oxidized titanium. Nearly linear voltage-current characteristics\nwere measured at temperatures down to $T \\sim \\unit[20]{mK}$ for films with\nsheet resistivity up to as high as $\\sim \\unit[7]{k\\Omega}$, i.e. about an\norder of magnitude higher than our previous findings for weakly oxidized Cr.\nOur analysis indicates that such an improvement can help to create an\nadvantageous high-impedance environment for different Coulomb blockade devices.\nFurther properties of the Ti film addressed in this work show a promise of\nlow-noise behavior of the resistors when applied in different realizations of\nthe quantum standard of current.",
        "positive": "Optical orientation of a single Mn spin in a quantum dot: Role of\n  carrier spin relaxation: In order to explain the recently observed phenomenon of optical orientation\nof a single Mn spin residing inside a quantum dot, a process of Mn spin\nrelaxation with characteristic timescale of tens of nanoseconds had been\ninvoked. We show that after taking into account the mixing of states of the\nexciton and the Mn spin (due to the sp-d exchange interaction), the observed Mn\noptical orientation time can be explained by invoking only the processes of\ncarrier spin relaxation."
    },
    {
        "anchor": "Photon-assisted scattering and magnetoconductivity oscillations in a\n  strongly correlated 2D electron system formed on the surface of liquid helium: The influence of strong internal forces on photon-assisted scattering and on\nthe displacement mechanism of magnetoconductivity oscillations in a\ntwo-dimensional (2D) electron gas is theoretically studied. The theory is\napplied to the highly correlated system of surface electrons on liquid helium\nunder conditions that the microwave frequency is substantially different from\ninter-subband resonance frequencies. A strong dependence of the amplitude of\nmagnetoconductivity oscillations on the electron density is established. The\npossibility of experimental observation of such oscillations caused by\nphoton-assisted scattering is discussed.",
        "positive": "Lifetime of the first and second collective excitations in metallic\n  nanoparticles: We determine the lifetime of the surface plasmon in metallic nanoparticles\nunder various conditions, concentrating on the Landau damping, which is the\ndominant mechanism for intermediate-size particles. Besides the main\ncontribution to the lifetime, which smoothly increases with the size of the\nparticle, our semiclassical evaluation yields an additional oscillating\ncomponent. For the case of noble metal particles embedded in a dielectric\nmedium, it is crucial to consider the details of the electronic confinement; we\nshow that in this case the lifetime is determined by the shape of the\nself-consistent potential near the surface. Strong enough perturbations may\nlead to the second collective excitation of the electronic system. We study its\nlifetime, which is limited by two decay channels: Landau damping and\nionization. We determine the size dependence of both contributions and show\nthat the second collective excitation remains as a well defined resonance."
    },
    {
        "anchor": "Crossover between strong and weak measurement in interacting many-body\n  systems: Measurements with variable system-detector interaction strength, ranging from\nweak to strong, have been recently reported in a number of electronic\nnanosystems. In several such instances many-body effects play a significant\nrole. Here we consider the weak--to--strong crossover for a setup consisting of\nan electronic Mach-Zehnder interferometer, where a second interferometer is\nemployed as a detector. In the context of a conditional which-path protocol, we\ndefine a generalized conditional value (GCV), and determine its full crossover\nbetween the regimes of weak and strong (projective) measurement. We find that\nthe GCV has an oscillatory dependence on the system-detector interaction\nstrength. These oscillations are a genuine many-body effect, and can be\nexperimentally observed through the voltage dependence of cross current\ncorrelations.",
        "positive": "Acoustic Wave Induced FMR Assisted Spin-Torque Switching of\n  Perpendicular MTJs with Anisotropy Variation: We have investigated Surface Acoustic Wave (SAW) induced ferromagnetic\nresonance (FMR) assisted Spin Transfer Torque (STT) switching of perpendicular\nMTJ (p-MTJ) with inhomogeneities using micromagnetic simulations that include\nthe effect of thermal noise. With suitable frequency excitation, the SAW can\ninduce ferromagnetic resonance in magnetostrictive materials, and the\nmagnetization can precesses in a cone with high deflection from the\nperpendicular direction. With incorporation of inhomogeneity via lateral\nanisotropy variation as well as room temperature thermal noise, the\nmagnetization precession in different gains can be significantly incoherent.\nInterestingly, the precession in different grains are found to be in phase,\neven though the precession amplitude (angle of deflection from the\nperpendicular direction) vary across grains of different anisotropy.\nNevertheless, the high mean deflection angle can complement the STT switching\nby reducing the STT current significantly; even though the applied stress\ninduced change in anisotropy is much lower than the total anisotropy barrier.\nThis work indicates that SAW assisted switching can improve energy efficiency\nwhile being scalable to very small dimensions, which is technologically\nimportant for STT-RAM and elucidates the physical mechanism for the potential\nrobustness of this paradigm in realistic scenarios with thermal noise and\nmaterial inhomogeneity"
    },
    {
        "anchor": "Solid argon as a possible substrate for quasi-freestanding silicene: We study the structural and electronic properties of silicene on solid\nAr(111) substrate using ab-initio calculations. We demonstrate that due to weak\ninteraction quasi-freestanding silicene is realized in this system. The small\nbinding energy of only $-32$ meV per Si atom also indicates the possibility to\nseparate silicene from the solid Ar(111) substrate. In addition, a band gap of\n$11$ meV and a significant splitting of the energy levels due to spin-orbit\ncoupling are observed.",
        "positive": "Generation and control of spin-polarized photocurrents in GaMnAs\n  heterostructures: Photocurrents are calculated for a specially designed GaMnAs semiconductor\nheterostructure. The results reveal regions in the infrared range of the energy\nspectrum in which the proposed structure is remarkably spin-selective. For such\nphoton energies, the generated photocurrents are strongly spin-polarized.\nApplication of a relatively small static bias in the growth direction of the\nstructure is predicted to efficiently reverse the spin-polarization for some\nphoton energies. This behavior suggests the possibility of conveniently simple\nswitching mechanisms. The physics underlying the results is studied and\nunderstood in terms of the spin-dependent properties emerging from the\nparticular potential profile of the structure."
    },
    {
        "anchor": "Radial fluctuations induced stabilization of the ordered state in two\n  dimensional classical clusters: Melting of two dimensional (2D) clusters of classical particles is studied\nusing Brownian dynamics and Langevin molecular dynamics simulations. The\nparticles are confined by a circular hard wall or a parabolic external\npotential and interact through a dipole or a screened Coulomb potential. We\nfound that with decreasing strength of the inter--particle interaction clusters\nwith short-range inter-particle interaction which are confined by a hard wall\nexhibit a re-entrant behavior in its orientational order.",
        "positive": "Observation of Coulomb blockade in nanostructured epitaxial bilayer\n  graphene on SiC: We study electron transport in nanostructures patterned in bilayer graphene\npatches grown epitaxially on SiC as a function of doping, magnetic field, and\ntemperature. Away from charge neutrality transport is only weakly modulated by\nchanges in carrier concentration induced by a local side-gate. At low n-type\ndoping close to charge neutrality, electron transport resembles that in\nexfoliated graphene nanoribbons and is well described by tunnelling of single\nelectrons through a network of Coulomb-blockaded islands. Under the influence\nof an external magnetic field, Coulomb blockade resonances fluctuate around an\naverage energy and the gap shrinks as a function of magnetic field. At charge\nneutrality, however, conduction is less insensitive to external magnetic\nfields. In this regime we also observe a stronger suppression of the\nconductance below $T^*$, which we interpret as a sign of broken interlayer\nsymmetry or strong fluctuations in the edge/potential disorder."
    },
    {
        "anchor": "A split-cavity design for the incorporation of a DC bias in a 3D\n  microwave cavity: We report on a technique for applying a DC bias in a 3D microwave cavity. We\nachieve this by isolating the two halves of the cavity with a dielectric and\ndirectly using them as DC electrodes. As a proof of concept, we embed a\nvariable capacitance diode in the cavity and tune the resonant frequency with a\nDC voltage, demonstrating the incorporation of a DC bias into the 3D cavity\nwith no measurable change in its quality factor at room temperature. We also\ncharacterize the architecture at millikelvin temperatures and show that the\nsplit cavity design maintains a quality factor $Q_\\text{i} \\sim 8.8 \\times\n10^5$, making it promising for future quantum applications.",
        "positive": "Projective Ribbon Permutation Statistics: a Remnant of non-Abelian\n  Braiding in Higher Dimensions: In a recent paper, Teo and Kane proposed a 3D model in which the defects\nsupport Majorana fermion zero modes. They argued that exchanging and twisting\nthese defects would implement a set R of unitary transformations on the zero\nmode Hilbert space which is a 'ghostly' recollection of the action of the braid\ngroup on Ising anyons in 2D. In this paper, we find the group T_{2n} which\ngoverns the statistics of these defects by analyzing the topology of the space\nK_{2n} of configurations of 2n defects in a slowly spatially-varying gapped\nfree fermion Hamiltonian: T_{2n}\\equiv {\\pi_1}(K_{2n})$. We find that the group\nT_{2n}= Z \\times T^r_{2n}, where the 'ribbon permutation group' T^r_{2n} is a\nmild enhancement of the permutation group S_{2n}: T^r_{2n} \\equiv \\Z_2 \\times\nE((Z_2)^{2n}\\rtimes S_{2n}). Here, E((Z_2)^{2n}\\rtimes S_{2n}) is the 'even\npart' of (Z_2)^{2n} \\rtimes S_{2n}, namely those elements for which the total\nparity of the element in (Z_2)^{2n} added to the parity of the permutation is\neven. Surprisingly, R is only a projective representation of T_{2n}, a\npossibility proposed by Wilczek. Thus, Teo and Kane's defects realize\n`Projective Ribbon Permutation Statistics', which we show to be consistent with\nlocality. We extend this phenomenon to other dimensions, co-dimensions, and\nsymmetry classes. Since it is an essential input for our calculation, we review\nthe topological classification of gapped free fermion systems and its relation\nto Bott periodicity."
    },
    {
        "anchor": "Strongly correlated two-dimensional plasma explored from entropy\n  measurements: Charged plasma and Fermi liquid are two distinct states of electronic matter\nintrinsic to dilute two-dimensional electron systems at elevated and low\ntemperatures, respectively. Probing their thermodynamics represents challenge\nbecause of lacking an adequate technique. Here we report thermodynamic method\nto measure the entropy per electron in gated structures. Our technique appears\nto be three orders of magnitude superior in sensitivity to the ac calorimetry,\nallowing entropy measurements with only $10^8$ electrons. This enables us to\ninvestigate the correlated plasma regime, previously inaccessible\nexperimentally in two-dimensional electron systems in semiconductors. In\nexperiments with clean two-dimensional electron system in Si-based structures\nwe traced entropy evolution from the plasma to Fermi-liquid regime by varying\nelectron density. We reveal that the correlated plasma regime can be mapped\nonto the ordinary non-degenerate Fermi gas with an interaction-enhanced\ntemperature dependent effective mass. Our method opens up new horizons in\nstudies of low-dimensional electron systems.",
        "positive": "Lecture Notes on Berry Phases and Topology: In these notes, we review the role of Berry phases and topology in\nnoninteracting electron systems. Topics including the adiabatic theorem,\nparallel transport, and Wannier functions are reviewed, with a focus on the\nconnection to topological insulators."
    },
    {
        "anchor": "Coherent Flux Tunneling Through NbN Nanowires: We demonstrate evidence of coherent magnetic flux tunneling through\nsuperconducting nanowires patterned in a thin highly disordered NbN film. The\nphenomenon is revealed as a superposition of flux states in a fully metallic\nsuperconducting loop with the nanowire acting as an effective tunnel barrier\nfor the magnetic flux, and reproducibly observed in different wires. The flux\nsuperposition achieved in the fully metallic NbN rings proves the universality\nof the phenomenon previously reported for InOx. We perform microwave\nspectroscopy and study the tunneling amplitude as a function of the wire width,\ncompare the experimental results with theories, and estimate the parameters for\nexisting theoretical models.",
        "positive": "Dark and Bright Excitonic States in Nitride Quantum Dots: Formation of excitonic states in quantum dots of nitride based III-V\nsemiconductors GaN and AlN including coulomb and exchange interactions are\ninvestigated. Dark exciton formation is found to occur for both GaN quantum\ndots(QDs) with wurtzite structure having positive crystal field splitting and\nGaN and AlN QDs with zero crystal field splitting with a transition from dark\nto bright exciton at about 40{\\AA}. In wurtzite AlN QDs with negative crystal\nfield splitting the splitting between the dark and bright excitonic states is\nvery small and vanishes at about 15{\\AA}."
    },
    {
        "anchor": "Switching Mechanism in Single-Layer Molybdenum Disulfide Transistors: an\n  Insight into Current Flow across Schottky Barriers: In this article, we study the properties of metal contacts to single-layer\nmolybdenum disulfide (MoS2) crystals, revealing the nature of switching\nmechanism in MoS2 transistors. On investigating transistor behavior as contact\nlength changes, we find that the contact resistivity for metal/MoS2 junctions\nis defined by contact area instead of contact width. The minimum gate dependent\ntransfer length is ~0.63 {\\mu}m in the on-state for metal (Ti) contacted\nsingle-layer MoS2. These results reveal that MoS2 transistors are Schottky\nbarrier transistors, where the on/off states are switched by the tuning the\nSchottky barriers at contacts. The effective barrier heights for source and\ndrain barriers are primarily controlled by gate and drain biases, respectively.\nWe discuss the drain induced barrier narrowing effect for short channel\ndevices, which may reduce the influence of large contact resistance for MoS2\nSchottky barrier transistors at the channel length scaling limit.",
        "positive": "Magnonic black holes: We show that the interaction between spin-polarized current and magnetization\ndynamics can be used to implement black-hole and white-hole horizons for\nmagnons - the quanta of oscillations in the magnetization direction in magnets.\nWe consider three different systems: easy-plane ferromagnetic metals, isotropic\nantiferromagnetic metals, and easy-plane magnetic insulators. Based on\navailable experimental data, we estimate that the Hawking temperature can be as\nlarge as 1 K. We comment on the implications of magnonic horizons for spin-wave\nscattering and transport experiments, and for magnon entanglement."
    },
    {
        "anchor": "Role of electron-electron interactions in nonlinear transport in 2D\n  electron systems: We study the temperature evolution of the non-linear oscillatory\nmagnetoresistance in a high-mobility two-dimensional electron system subject to\na strong dc electric field. We find that the decay of the oscillation amplitude\nwith increasing temperature originates primarily from increasing quantum\nscattering rate entering the Dingle factor. We attribute this behavior to\nelectron-electron interaction effects.",
        "positive": "Magnetism of topological boundary states induced by boron substitution\n  in graphene nanoribbons: Graphene nanoribbons (GNRs), low-dimensional platforms for carbon-based\nelectronics, show the promising perspective to also incorporate spin\npolarization in their conjugated electron system. However, magnetism in GNRs is\ngenerally associated to localized states around zigzag edges, difficult to\nfabricate and with high reactivity. Here we demonstrate that magnetism can also\nbe induced away from physical GNR zigzag edges through atomically precise\nengineering topological defects in its interior. A pair of substitutional boron\natoms inserted in the carbon backbone breaks the conjugation of their\ntopological bands and builds two spin-polarized boundary states around. The\nspin state was detected in electrical transport measurements through\nboron-substituted GNRs suspended between tip and sample of a scanning tunneling\nmicroscope. First-principle simulations find that boron pairs induce a spin 1,\nwhich is modified by tuning the spacing between pairs. Our results demonstrate\na route to embed spin chains in GNRs, turning them basic elements of spintronic\ndevices."
    },
    {
        "anchor": "Electrical Control over Phonon Polarization in Strained Graphene: We explore the tunability of the phonon polarization in suspended uniaxially\nstrained graphene by magneto-phonon resonances. The uniaxial strain lifts the\ndegeneracy of the LO and TO phonons, yielding two cross-linearly polarized\nphonon modes and a splitting of the Raman G peak. We utilize the strong\nelectron-phonon coupling in graphene and the off-resonant coupling to a\nmagneto-phonon resonance to induce a gate-tunable circular phonon dichroism.\nThis, together with the strain-induced splitting of the G peak, allows us to\ncontrollably tune the two linearly polarized G mode phonons into circular\nphonon modes. We are able to achieve a circular phonon polarization of up to 40\n% purely by electrostatic fields and can reverse its sign by tuning from\nelectron to hole doping. This provides unprecedented electrostatic control over\nthe angular momentum of phonons, which paves the way toward phononic\napplications.",
        "positive": "Experimental realisation of Dual Periodicity Moir\u00e9 Superlattice in a\n  MoSe$_2$/WSe$_2$ Heterobilayer: Moir\\'e structures in van der Waals heterostructures lead to emergent\nphenomena including superconductivity in twisted bilayer graphene and optically\naccessible strongly-correlated electron states in transition metal\ndichalcogenide heterobilayers. Dual periodicity moir\\'e structures (DPMS)\nformed in layered structures with more than two layers have been shown to lead\nto ferromagnetism and multiple secondary Dirac points in TBG. Whilst in\nprinciple it is possible to obtain DPMS in bilayers there has not been clear\nexperimental evidence of this yet. In this paper we present signatures of DPMS\nin a twisted MoSe$_2$/WSe$_2$ bilayer revealed by resonance Raman spectroscopy.\nWe observed zone-folded acoustic and optical phonon modes with a wavevector\ntwice of the moir\\'e wavevector, evidence of a dual periodicity moir\\'e\nheterostructure. These results simultaneously open up opportunities for new\nemergent phenomena and an optical method for characterising DPMS in a wide\nrange of van der Waals heterostructures."
    },
    {
        "anchor": "Spin Orbit Torque in two dimensional Antiferromagnetic Topological\n  Insulators: We investigate spin transport in two dimensional ferromagnetic (FTI) and\nantiferromagnetic (AFTI) topological insulators. In presence of an in plane\nmagnetization AFTI supports zero energy modes, which enables topologically\nprotected edge conduction at low energy. We address the nature of\ncurrent-driven spin torque in these structures and study the impact of\nspin-independent disorder. Interestingly, upon strong disorder the spin torque\ndevelops an antidamping component (i.e. {\\em even} upon magnetization reversal)\nalong the edges, which could enable current-driven manipulation of the\nantiferromagnetic order parameter. This antidamping torque decreases when\nincreasing the system size and when the system enters the trivial insulator\nregime.",
        "positive": "Nanoscale vector AC magnetometry with a single nitrogen-vacancy center\n  in diamond: Detection of AC magnetic fields at the nanoscale is critical in applications\nranging from fundamental physics to materials science. Isolated quantum spin\ndefects, such as the nitrogen-vacancy center in diamond, can achieve the\ndesired spatial resolution with high sensitivity. Still, vector AC magnetometry\ncurrently relies on using different orientations of an ensemble of sensors,\nwith degraded spatial resolution, and a protocol based on a single NV is\nlacking. Here we propose and experimentally demonstrate a protocol that\nexploits a single NV to reconstruct the vectorial components of an AC magnetic\nfield by tuning a continuous driving to distinct resonance conditions. We map\nthe spatial distribution of an AC field generated by a copper wire on the\nsurface of the diamond. The proposed protocol combines high sensitivity, broad\ndynamic range, and sensitivity to both coherent and stochastic signals, with\nbroad applications in condensed matter physics, such as probing spin\nfluctuations."
    },
    {
        "anchor": "Ferrotronics for the creation of band gaps in Graphene: We experimentally demonstrate a simple graphene/ ferrolectric device, termed\nFerrotronic (electronic effect from ferroelectric) device in which the\nband-structure of single-layer graphene is modified. The device architecture\nconsists of graphene deposited on a ferroelectric substrate which encodes a\nperiodic surface potential achieved through domain engineering. This structure\ntakes advantage of the nature of conduction through graphene to modulate the\nFermi velocity of the charge carriers by the variations in surface potential,\nleading to the emergence of energy mini-bands and a band gap at the\nsuperlattice Brillouin zone boundary. Our work represents a simple route to\nbuilding circuits whose functionality is controlled by the underlying\nsubstrate.",
        "positive": "Quantum dephasing of interacting quantum dot induced by the\n  superconducting proximity effect: The proximity effect (PE) between superconductor and confined electrons can\ninduce the effective pairing phenomena of electrons in nanowire or quantum dot\n(QD). Through interpreting the PE as an exchange of virtually quasi-excitation\nin a largely gapped superconductor, we found that there exists another induced\ndynamic process. Unlike the effective pairing that mixes the QD electron states\ncoherently, this extra process leads to dephasing of the QD. In a case study,\nthe dephasing time is inversely proportional to the Coulomb interaction\nstrength between two electrons in the QD. Further theoretical investigations\nimply that this dephasing effect can decrease the quality of the zero\ntemperature mesoscopic electron transportation measurements by lowering and\nbroadening the corresponding differential conductance peaks."
    },
    {
        "anchor": "The chirality-dependent second-order spin current in systems with\n  time-reversal symmetry: Spin currents proportional to the first- and second-order of the electric\nfield are calculated in a specific tight-binding model with time-reversal\nsymmetry. Specifically, a tight-binding model with time-reversal symmetry is\nconstructed with chiral hopping and spin-orbit coupling. The spin conductivity\nof the model is calculated using the Boltzmann equation. As a result, it is\nclarified that the first-order spin current of the electric field vanishes,\nwhile the second-order spin current can be finite. Furthermore, the spin\ncurrent changes its sign by reversing the chirality of the model. The present\nresults reveal the existence of spin currents in systems with time-reversal\nsymmetry depending on the chirality of the system. They may provide useful\ninformation for understanding the chirality-dependent spin polarization\nphenomena in systems with time-reversal symmetry.",
        "positive": "Charging energy spectrum of black phosphorus quantum dots: We present a theoretical study of the charging effects in single and double\nlayer black phosphorus quantum dots (BPQDs) with lateral sizes of 2 nm and 3\nnm. We demonstrate that the charging of BPQDs are able to store up to an\n$N_{max}$ electron (that depends on the lateral size and number of layers in\nthe QD), after which structural instabilities arises. For example, 3 nm wide\nhydrogen-passivated single layer BPQDs can hold a maximum of 16 electrons, and\nan additional electron causes the expelling of hydrogen atoms from the QD\nborders. We also calculated the additional energy ($E_A$) spectrum. For single\nlayer QDs with 2 and 3 nm of lateral sizes, the average $E_A$ is around 0.4 eV\nand 0.3 eV, respectively. For double layer QDs with the same sizes, the average\n$E_A$ is around 0.25 eV and 0.2 eV, respectively."
    },
    {
        "anchor": "Exciton diffusion in air-suspended single-walled carbon nanotubes: Direct measurements of the diffusion length of excitons in air-suspended\nsingle-walled carbon nanotubes are reported. Photoluminescence microscopy is\nused to identify individual nanotubes and to determine their lengths and chiral\nindices. Exciton diffusion length is obtained by comparing the dependence of\nphotoluminescence intensity on the nanotube length to numerical solutions of\ndiffusion equations. We find that the diffusion length in these clean, as-grown\nnanotubes is significantly longer than those reported for micelle-encapsulated\nnanotubes.",
        "positive": "Blowing Polar Skyrmion Bubbles in Oxide Superlattices: Particle-like topological structures such as skyrmions and vortices have\ngarnered ever-increasing interests due to the rich physical insights and\npotential broad applications. Here we discover the reversible switching between\npolar skyrmion bubbles and ordered vortex arrays in ferroelectric superlattices\nunder an electric field, reminiscent of the Plateau-Raleigh instability in\nfluid mechanics. Electric field phase diagram is constructed, showing wide\nstability window for the observed polar skyrmions. This study is a\ndemonstration for the computational design of ferroelectric topological\nstructures and field-induced topological phase transitions."
    },
    {
        "anchor": "Graphene-based nanodynamometer: A new concept of an electromechanical nanodynamometer based on the relative\ndisplacement of layers of bilayer graphene is proposed. In this\nnanodynamometer, force acting on one of the graphene layers causes the relative\ndisplacement of this layer and related change of conductance between the\nlayers. Such a force can be determined by measurements of the tunneling\nconductance between the layers. Dependences of the interlayer interaction\nenergy and the conductance between the graphene layers on their relative\nposition are calculated within the first-principles approach corrected for van\nder Waals interactions and the Bardeen method, respectively. The\ncharacteristics of the nanodynamometer are determined and its possible\napplications are discussed.",
        "positive": "Unusual Spin Polarization in the Chirality Induced Spin Selectivity: Chirality-induced spin selectivity (CISS) refers to the fact that electrons\nget spin polarized after passing through organic chiral molecules in a\nnanoscale device. In CISS, chiral molecules are commonly believed to be a spin\nfilter through which one favored spin transmits and the opposite spin gets\nreflected, i.e., transmitted and reflected electrons exhibit opposite spin\npolarization. In this work, we point out that such a spin filter scenario\ncontradicts the principle that equilibrium spin current must vanish. Instead,\nwe find that both transmitted and reflected electrons present the same type\nspin polarization, which is actually ubiquitous for a two-terminal device. More\naccurately, chiral molecules play the role of a spin polarizer rather than a\nspin filter. The direction of spin polarization is determined by the molecule\nchirality and the electron incident direction. And the magnitude of spin\npolarization replies on local spin-orbit coupling in the device. Our work\nbrings a deeper understanding on CISS and interprets recent experiments, for\nexample, the CISS-driven anomalous Hall effect."
    },
    {
        "anchor": "Towards Chirality Control of Graphene Nanoribbons Embedded in Hexagonal\n  Boron Nitride: The integrated inplane growth of two dimensional materials with similar\nlattices, but distinct electrical properties, could provide a promising route\nto achieve integrated circuitry of atomic thickness. However, fabrication of\nedge specific GNR in the lattice of hBN still remains an enormous challenge for\npresent approaches. Here we developed a two step growth method and successfully\nachieved sub 5 nm wide zigzag and armchair GNRs embedded in hBN, respectively.\nFurther transport measurements reveal that the sub 7 nm wide zigzag GNRs\nexhibit openings of the band gap inversely proportional to their width, while\nnarrow armchair GNRs exhibit some fluctuation in the bandgap width\nrelationship.This integrated lateral growth of edge specific GNRs in hBN brings\nsemiconducting building blocks to atomically thin layer, and will provide a\npromising route to achieve intricate nanoscale electrical circuits on high\nquality insulating hBN substrates.",
        "positive": "Electric and Magnetic Tuning Between the Trivial and Topological Phases\n  in InAs/GaSb Double Quantum Wells: Among the theoretically predicted two-dimensional topological insulators,\nInAs/GaSb double quantum wells (DQWs) have a unique double-layered structure\nwith electron and hole gases separated in two layers, which enables tuning of\nthe band alignment via electric and magnetic fields. However, the rich\ntrivial-topological phase diagram has yet to be experimentally explored. We\npresent an in situ and continuous tuning between the trivial and topological\ninsulating phases in InAs/GaSb DQWs through electrical dual-gating.\nFurthermore, we show that an in-plane magnetic field shifts the electron and\nhole bands relatively to each other in momentum space, functioning as a\npowerful tool to discriminate between the topologically distinct states."
    },
    {
        "anchor": "Possible origin of the 0.5 plateau in the ballistic conductance of\n  quantum point contacts: A non-equilibrium Green function formalism (NEGF) is used to study the\nconductance of a side-gated quantum point contact (QPC) in the presence of\nlateral spin-orbit coupling (LSOC). A small difference of bias voltage between\nthe two side gates (SGs) leads to an inversion asymmetry in the LSOC between\nthe opposite edges of the channel. In single electron modeling of transport,\nthis triggers a spontaneous but insignificant spin polarization in the QPC.\nHowever, the spin polarization of the QPC is enhanced substantially when the\neffect of electron-electron interaction is included. The spin polarization is\nstrong enough to result in the occurrence of a conductance plateau at 0.5G0 (G0\n= 2e2/h) in the absence of any external magnetic field. In our simulations of a\nmodel QPC device, the 0.5 plateau is found to be quite robust and survives up\nto a temperature of 40K. The spontaneous spin polarization and the resulting\nmagnetization of the QPC can be reversed by flipping the polarity of the source\nto drain bias or the potential difference between the two SGs. These numerical\nsimulations are in good agreement with recent experimental results for\nside-gated QPCs made from the low band gap semiconductor InAs.",
        "positive": "Wafer-scale low-disorder 2DEG in $^{28}$Si/SiGe without an epitaxial Si\n  cap: We grow $^{28}$Si/SiGe heterostructures by reduced-pressure chemical vapor\ndeposition and terminate the stack without an epitaxial Si cap but with an\namorphous Si-rich layer obtained by exposing the SiGe barrier to dichlorosilane\nat 500 {\\deg}C. As a result, $^{28}$Si/SiGe heterostructure field-effect\ntransistors feature a sharp semiconductor/dielectric interface and support a\ntwo-dimensional electron gas with enhanced and more uniform transport\nproperties across a 100 mm wafer. At T = 1.7 K we measure a high mean mobility\nof (1.8$\\pm$0.5)$\\times$10$^5$ cm$^2$/Vs and a low mean percolation density of\n(9$\\pm$1)$\\times$10$^{10}$ cm$^{-2}$. From the analysis of Shubnikov-de Haas\noscillations at T = 190 mK we obtain a long mean single particle relaxation\ntime of (8.1$\\pm$0.5) ps, corresponding to a mean quantum mobility and quantum\nlevel broadening of (7.5$\\pm$0.6)$\\times$10$^4$ cm$^{2}$/Vs and (40$\\pm$3)\n$\\mu$eV, respectively, and a small mean Dingle ratio of (2.3$\\pm$0.2),\nindicating reduced scattering from long range impurities and a low-disorder\nenvironment for hosting high-performance spin-qubits."
    },
    {
        "anchor": "Fano description of single-hydrocarbon fluorescence excited by a\n  scanning tunneling microscope: The detection of fluorescence with submolecular resolution enables the\nexploration of spatially varying photon yields and vibronic properties at the\nsingle-molecule level. By placing individual polycyclic aromatic hydrocarbon\nmolecules into the plasmon cavity formed by the tip of a scanning tunneling\nmicroscope and a NaCl-covered Ag(111) surface, molecular light emission spectra\nare obtained that unravel vibrational progression. In addition, light spectra\nunveil a signature of the molecule even when the tunneling current is injected\nwell separated from the molecular emitter. This signature exhibits a\ndistance-dependent Fano profile that reflects the subtle interplay between\ninelastic tunneling electrons, the molecular exciton and localized plasmons in\nat-distance as well as on-molecule fluorescence. The presented findings open\nthe path to luminescence of a different class of molecules than investigated\nbefore and contribute to the understanding of single-molecule luminescence at\nsurfaces in a unified picture.",
        "positive": "Controlling spin polarization of gapless states in defected trilayer\n  graphene with a gate voltage: Trilayer graphene exhibits valley-protected gapless states when the stacking\norder changes from ABC to CBA and a gate voltage is applied to outer layers.\nSome of these states survive strong distortions of the trilayer. For example,\nthey persist when the outer layers are partially devoid yielding a system of\ntwo trilayers of different stacking order connected by a strip of a single\ngraphene layer. Here we investigate how these states respond to another\nperturbation, i.e., the presence of magnetic defects, which we model as\npi-vacancies. We show that the gap states hybridize with the defect states and\nstrongly spin-split. More importantly, it is demonstrated that by changing the\ngate voltage value one can change the spin density of the gap states and the\ncorresponding currents at the Fermi level."
    },
    {
        "anchor": "Unraveling spin dynamics from charge fluctuations: The use of single electron spins in quantum dots as qubits requires detailed\nknowledge about the processes involved in their initialization and operation as\nwell as their relaxation and decoherence. In optical schemes for such spin\nqubits, spin-flip Raman as well as Auger processes play an important role, in\naddition to environment-induced spin relaxation. In this paper, we demonstrate\nhow to quantitatively access all the spin-related processes in one go by\nmonitoring the charge fluctuations of the quantum dot. For this, we employ\nresonance fluorescence and analyze the charge fluctuations in terms of\nwaiting-time distributions and full counting statistics characterized by\nfactorial cumulants.",
        "positive": "Propagation of Dirac waves through various temporal interfaces, slabs,\n  and crystals: We investigate the influence of the temporal variations of various medium\nparameters on the propagation of Dirac-type waves in materials where the\nquasiparticles are described by a generalized version of the pseudospin-1/2\nDirac equation. Our considerations also include the propagation of\nelectromagnetic waves in metamaterials with the Dirac-type dispersion. We focus\non the variations of the scalar and vector potentials, mass, Fermi velocity,\nand tilt velocity describing the Dirac cone tilt. We derive the scattering\ncoefficients associated with the temporal interfaces and slabs analytically and\nfind that the temporal scattering is caused by the changes of the mass, Fermi\nvelocity, and vector potential, but does not arise from the changes of the\nscalar potential and tilt velocity. We also explore the conditions under which\nthe temporal Brewster effect and total interband transition occur and calculate\nthe change in total wave energy. We examine bilayer Dirac temporal crystals\nwhere parameters switch between two different sets of values periodically and\nprove that these systems do not have momentum gaps. Finally, we assess the\npotential for observing these temporal scattering effects in experiments."
    },
    {
        "anchor": "Optical identification of atomically thin dichalcogenide crystals: We present a systematic study of the optical contrast of diselenide (NbSe2)\nand molybdenum disulphide (MoS2) flakes deposited onto Si wafers with a\nthermally grown SiO2 layer. We measure the optical contrast of flakes whose\nthickness ranges from 200 layers down to a monolayer using different\nillumination wavelengths in the visible spectrum. The refractive index of these\nthin crystals has been obtained from the measured optical contrast dependence\non the flake thickness by using a simple model based on the Fresnel law. With\nthe refractive index of these NbSe2 and MoS2 crystallites, the optical\nmicroscopy data can be quantitatively analyzed to determine the thickness of\nthe flakes in a fast and non-destructive way.",
        "positive": "Electron- and phonon transport in silicon nanowires: an atomistic\n  approach to thermoelectric properties: We compute both electron- and phonon transmissions in thin disordered silicon\nnanowires. Our atomistic approach is based on tight-binding and empirical\npotential descriptions of the electronic and phononic systems, respectively.\nSurface disorder is modeled by including surface silicon vacancies. It is shown\nthat the average phonon- and electron transmissions through long SiNWs\ncontaining many vacancies can be accurately estimated from the scattering\nproperties of the isolated vacancies using a recently proposed averaging method\n[Phys. Rev. Lett. 99, 076803 (2007)]. We apply this averaging method to surface\ndisordered SiNWs in the diameter range 1-3 nm to compute the thermoelectric\nfigure of merit, ZT. It is found that the phonon transmission is affected more\nby the vacancies than the electronic transmission leading to an increased\nthermoelectric performance of disordered wires, in qualitative agreement with\nrecent experiments. The largest ZT>3 is found in strongly disordered <111>\noriented wires with a diameter of 2 nm."
    },
    {
        "anchor": "Electrons scattering in the monolayer graphene with the short-range\n  impurities: Scattering problem for electrons in monolayer graphene with short-range\nperturbations of the types \"local chemical potential\" and \"local gap\" has been\nsolved. Zero gap and non-zero gap kinds of graphene are considered. The\ndetermined S-matrix can be used for calculation of such observables as\nconductance and optical absorption.",
        "positive": "Stable hydrogenated graphene edge types: Normal and reconstructed Klein\n  edges: Hydrogenated graphene edges are assumed to be either armchair, zigzag or a\ncombination of the two. We show that the zigzag is not the most stable fully\nhydrogenated structure along the <2-1-10> direction. Instead hydrogenated Klein\nand reconstructed Klein based edges are found to be energetically more\nfavourable, with stabilities approaching that of armchair edges. These new\nstructures \"unify\" graphene edge topology, the most stable flat hydrogenated\ngraphene edges always consisting of pairwise bonded C2H4 edge groups,\nirrespective the edge orientation. When edge rippling is included, CH3 edge\ngroups are most stable. These new fundamental hydrogen terminated edges have\nimportant implications for graphene edge imaging and spectroscopy, as well as\nmechanisms for graphene growth, nanotube cutting, and nanoribbon formation and\nbehaviour."
    },
    {
        "anchor": "Symmetry effects on the static and dynamic properties of coupled\n  magnetic oscillators: The effect of symmetry on the resonance spectra of antiferromagnetically\ncoupled oscillators has attracted new interest with the discovery of\nsymmetry-breaking induced anti-crossings. Here, we experimentally characterise\nthe resonance spectrum of a synthetic antiferromagnet Pt/CoFeB/Ru/CoFeB/Pt,\nwhere we are able to independently tune the effective magnetisation of the two\ncoupled magnets. To model our results we apply the mathematical methods of\ngroup theory to the solutions of the Landau Lifshitz Gilbert equation. This\ngeneral approach, usually applied to quantum mechanical systems, allows us to\nidentify the main features of the resonance spectrum in terms of symmetry\nbreaking and to make a direct comparison with crystal antiferromagnets.",
        "positive": "A study of the magnetotransport properties of the graphene (I.\n  Monolayer): We present a single electron approach to analyse the magnetotransport\nproperties of the monolayer graphene as a function of both, the gate voltage\nand the magnetic field; and, also, their evolution with temperature. The model\nproposed means the extension of our previous one developed for studying the\nquantum Hall and Shubnikov-de Haas effects of a two-dimensional electron system\nin a semiconductor quantum well. Now, the study in this framework of both\nphenomena in graphene involves including the presence of two bands and two\ndegeneracy valleys, (points K and K' in the reciprocal space). Based in a\nsingle electron approximation, we show it is capable to reproduce the entire\ncharacteristics observed in the experiments for the Hall and diagonal\nmagnetoconductivities (and the corresponding magnetoresistivities), as a\nfunction of the gate voltage and the magnetic field. In the model the observed\nHall plateaux series in the monolayer graphene, determined by the expression\n2(2n+1), arises in a natural way as a consequence of the particular\nquantization of the energy spectrum of graphene. Therefore, on the other hand\nthe proposed approach integrates the quantum Hall effects observed in graphene\nand quantum wells semiconductors"
    },
    {
        "anchor": "Third harmonic generation from graphene lying on different substrates:\n  Optical-phonon resonances and interference effects: Graphene is a nonlinear material which can be used as a saturable absorber,\nfrequency mixer and frequency multiplier. We investigate the third harmonic\ngeneration from graphene lying on different substrates, consisting of a\ndielectric (dispersionless or polar), metalized or non-metalized on the back\nside. We show that the third harmonic intensity emitted from graphene lying on\na substrate, can be increased by orders of magnitude as compared to the\nisolated graphene, due the LO-phonon resonances in a polar dielectric or due to\nthe interference effects in the substrates metalized on the back side. In some\nfrequency intervals, the presence of the polar dielectric substrate compensates\nthe strongly decreasing with $\\omega$ frequency dependence of the third-order\nconductivity of graphene making the response almost frequency independent.",
        "positive": "A survey of fractured SrTiO$_3$ surfaces: from the micro-meter to\n  nano-meter scale: Cross-sectional scanning tunneling microscopy was utilized to study fractured\nperovskie oxide surfaces. It was found for the non-cleavable perovskite oxide,\nSrTiO$_{3}$, that atomically flat terraces could be routinely created with a\ncontrolled fracturing procedure. Optical and scanning electron microscopy as\nwell as a profilometer were used to obtain the information from sub-millimeter\nto sub-micrometer scales of the fractured surface topography."
    },
    {
        "anchor": "Antilocalization of Coulomb Blockade in a Ge-Si Nanowire: The distribution of Coulomb blockade peak heights as a function of magnetic\nfield is investigated experimentally in a Ge-Si nanowire quantum dot. Strong\nspin-orbit coupling in this hole-gas system leads to antilocalization of\nCoulomb blockade peaks, consistent with theory. In particular, the peak height\ndistribution has its maximum away from zero at zero magnetic field, with an\naverage that decreases with increasing field. Magnetoconductance in the\nopen-wire regime places a bound on the spin-orbit length ($l_{so}$ < 20 nm),\nconsistent with values extracted in the Coulomb blockade regime ($l_{so}$ < 25\nnm).",
        "positive": "Bulk Fermi-surface of the Weyl type-II semi-metallic candidate MoTe2: The electronic structure of WTe$_2$ and orthorhombic $\\gamma-$MoTe$_2$, are\nclaimed to contain pairs of Weyl type-II points. A series of ARPES experiments\nclaim a broad agreement with these predictions. We synthesized single-crystals\nof MoTe$_2$ through a Te flux method to validate these predictions through\nmeasurements of its bulk Fermi surface (FS) \\emph{via} quantum oscillatory\nphenomena. We find that the superconducting transition temperature of\n$\\gamma-$MoTe$_2$ depends on disorder as quantified by the ratio between the\nroom- and low-temperature resistivities, suggesting the possibility of an\nunconventional superconducting pairing symmetry. Similarly to WTe$_2$, the\nmagnetoresistivity of $\\gamma-$MoTe$_2$ does not saturate at high magnetic\nfields and can easily surpass $10^{6}$ \\%. Remarkably, the analysis of the de\nHaas-van Alphen (dHvA) signal superimposed onto the magnetic torque, indicates\nthat the geometry of its FS is markedly distinct from the calculated one. The\ndHvA signal also reveals that the FS is affected by the Zeeman-effect\nprecluding the extraction of the Berry-phase. A direct comparison between the\nprevious ARPES studies and density-functional-theory (DFT) calculations reveals\na disagreement in the position of the valence bands relative to the Fermi level\n$\\varepsilon_F$. Here, we show that a shift of the DFT valence bands relative\nto $\\varepsilon_F$, in order to match the ARPES observations, and of the DFT\nelectron bands to explain some of the observed dHvA frequencies, leads to a\ngood agreement between the calculations and the angular dependence of the FS\ncross-sectional areas observed experimentally. However, this relative\ndisplacement between electron- and hole-bands eliminates their crossings and,\ntherefore, the Weyl type-II points predicted for $\\gamma-$MoTe$_2$."
    },
    {
        "anchor": "Electron Waiting Times in Mesoscopic Conductors: Electron transport in mesoscopic conductors has traditionally involved\ninvestigations of the mean current and the fluctuations of the current. A\ncomplementary view on charge transport is provided by the distribution of\nwaiting times between charge carriers, but a proper theoretical framework for\ncoherent electronic systems has so far been lacking. Here we develop a quantum\ntheory of electron waiting times in mesoscopic conductors expressed by a\ncompact determinant formula. We illustrate our methodology by calculating the\nwaiting time distribution for a quantum point contact and find a cross-over\nfrom Wigner-Dyson statistics at full transmission to Poisson statistics close\nto pinch-off. Even when the low-frequency transport is noiseless, the electrons\nare not equally spaced in time due to their inherent wave nature. We discuss\nthe implications for renewal theory in mesoscopic systems and point out several\nanalogies with energy level statistics and random matrix theory.",
        "positive": "Lifshitz and Excited State Quantum Phase Transitions in Microwave Dirac\n  Billiards: We present experimental results for the density of states (DOS) of a\nsuperconducting microwave Dirac billiard which serves as an idealized model for\nthe electronic properties of graphene. The DOS exhibits two sharp peaks which\nevolve into van Hove singularities with increasing system size. They divide the\nband structure into regions governed by the \\emph{relativistic} Dirac equation\nand by the \\emph{non-relativistic} Schr\\\"odinger equation, respectively. We\ndemonstrate that in the thermodynamic limit a topological transition appears as\na neck-disrupting Lifshitz transition in the number susceptibility and as an\nexcited state transition in the electronic excitations. Furthermore, we recover\nthe finite-size scaling typical for excited state quantum phase transitions\ninvolving logarithmic divergences and identify a quasi-order parameter."
    },
    {
        "anchor": "Adiabatic Charge Pumping through Quantum Dots in the Coulomb Blockade\n  Regime: We investigate the influence of the Coulomb interaction on the adiabatic\npumping current through quantum dots. Using nonequilibrium Green's functions\ntechniques, we derive a general expression for the current based on the\ninstantaneous Green's function of the dot. We apply this formula to study the\ndependence of the charge pumped per cycle on the time-dependent pumping\npotentials. The possibility of charge quantization in the presence of a finite\nCoulomb repulsion energy is investigated in the light of recent experiments.",
        "positive": "Thermodynamic properties of an electron gas in a two-dimensional quantum\n  dot: an approach using density of states: Potential applications of quantum dots in the nanotechnology industry make\nthese systems an important field of study in various areas of physics. In\nparticular, thermodynamics has a significant role in technological innovations.\nWith this in mind, we studied some thermodynamic properties in quantum dots,\nsuch as entropy and heat capacity, as a function of the magnetic field over a\nwide range of temperatures. The density of states plays an important role in\nour analyses. At low temperatures, the variation in the magnetic field induces\nan oscillatory behavior in all thermodynamic properties. The depopulation of\nsubbands is the trigger for the appearance of the oscillations."
    },
    {
        "anchor": "Stationary drag photocurrent caused by strong running wave in quantum\n  wire: quantization of current: The stationary current induced by a strong running potential wave in\none-dimensional system is studied. Such a wave can result from illumination of\na straight quantum wire with special grating or spiral quantum wire by\ncircular-polarized light. The wave drags electrons in the direction correlating\nwith the direction of the system symmetry and polarization of light. In a pure\nsystem the wave induces minibands in the accompanied system of reference. We\nstudy the effect in the presence of impurity scattering. The current is an\ninterplay between the wave drag and impurity braking. It was found that the\ndrag current is quantized when the Fermi level gets into energy gaps.",
        "positive": "Free fermions on a line: asymptotics of the entanglement entropy and\n  entanglement spectrum from full counting statistics: We consider the entanglement entropy for a line segment in the system of\nnoninteracting one-dimensional fermions at zero temperature. In the limit of a\nlarge segment length L, the leading asymptotic behavior of this entropy is\nknown to be logarithmic in L. We study finite-size corrections to this\nasymptotic behavior. Based on an earlier conjecture of the asymptotic expansion\nfor full counting statistics in the same system, we derive a full asymptotic\nexpansion for the von Neumann entropy and obtain first several corrections for\nthe Renyi entropies. Our corrections for the Renyi entropies reproduce earlier\nresults. We also discuss the entanglement spectrum in this problem in terms of\nsingle-particle occupation numbers."
    },
    {
        "anchor": "Radiative heat transfer and nonequilibrium Casimir-Lifshitz force in\n  many-body systems with planar geometry: A general theory of photon-mediated energy and momentum transfer in N-body\nplanar systems out of thermal equilibrium is introduced. It is based on the\ncombination of the scattering theory and the fluctuational-electrodynamics\napproach in many-body systems. By making a Landauer-like formulation of the\nheat transfer problem, explicit formulas for the energy transmission\ncoefficients between two distinct slabs as well as the self-coupling\ncoefficients are derived and expressed in terms of the reflection and\ntransmission coefficients of the single bodies. We also show how to calculate\nlocal equilibrium temperatures in such systems. An analogous formulation is\nintroduced to quantify momentum transfer coefficients describing\nCasimir-Lifshitz forces out of thermal equilibrium. Forces at thermal\nequilibrium are readily obtained as a particular case. As an illustration of\nthis general theoretical framework, we show on three-body systems how the\npresence of a fourth slab can impact equilibrium temperatures in heat-transfer\nproblems and equilibrium positions resulting from the forces acting on the\nsystem.",
        "positive": "Systematic study of the influence of coherent phonon wave packets on the\n  lasing properties of a quantum dot ensemble: Coherent phonons can greatly vary light-matter interaction in semiconductor\nnanostructures placed inside an optical resonator on an ultrafast time scale.\nFor an ensemble of quantum dots as active laser medium phonons are able to\ninduce a large enhancement or attenuation of the emission intensity, as has\nbeen recently demonstrated. The physics of this coupled phonon-exciton-photon\nsystem consists of various effects, which in the experiment typically cannot be\nclearly separated, in particular because a rather complex strain pulse impinges\non the quantum dot ensemble. Here we present a comprehensive theoretical study\nhow the laser emission is affected by phonon pulses of various shapes as well\nas by ensembles with different spectral distributions of the quantum dots. This\ngives insight into the fundamental interaction dynamics of the coupled\nphonon-exciton-photon system, while it allows us to clearly discriminate\nbetween two prominent effects: the adiabatic shifting of the ensemble and the\nshaking effect. This paves the way to a tailored laser emission controlled by\nphonons."
    },
    {
        "anchor": "Terahertz superlattice parametric oscillator: We report a GaAs/AlAs superlattice parametric oscillator. It was pumped by a\nmicrowave field (power few mW) and produced 3rd harmonic radiation (frequency\nnear 300 GHz). The nonlinearity of the active superlattice was due to Bragg\nreflections of conduction electrons at the superlattice planes. A theory of the\nnonlinearity indicates that parametric oscillation should be possible up to\nfrequencies above 10 THz. The active superlattice may be the object of further\nstudies of predicted extraordinary nonlinearities for THz fields.",
        "positive": "Optical measurement of electron spins in quantum dots: Quantum Zeno\n  effects: We describe the effects of the quantum back action under continuous optical\nmeasurement of electron spins in quantum dots. We consider the system\nexcitation by elliptically polarized light close to the trion resonance, which\nallows for the simultaneous spin orientation and measurement. We\nmicroscopically demonstrate that the nuclei-induced spin relaxation can be both\nsuppressed and accelerated by the continuous spin measurement due to the\nquantum Zeno and anti-Zeno effects, respectively. Our theoretical predictions\ncan be directly compared with the future experimental results and\nstraightforwardly generalized for the pump-probe experiments."
    },
    {
        "anchor": "High sensitivity cantilevers for measuring persistent currents in normal\n  metal rings: We propose a new approach to measuring persistent currents in normal metal\nrings. By integrating micron-scale metal rings into sensitive micromechanical\ncantilevers and using the cantilevers as torque magnetometers, it should be\npossible to measure the rings' persistent currents with greater sensitivity\nthan the SQUID-based and microwave resonator-based detectors used in the past.\nIn addition, cantilever-based detectors may allow for measurements in a cleaner\nelectromagnetic environment. We have fabricated ultra sensitive cantilevers\nwith integrated rings and measured their mechanical properties. We present an\nestimate of the persistent current sensitivity of these cantilever-based\ndetectors, focusing on the limits set by the cantilever's Brownian motion and\nthe shot noise in the laser interferometer that monitors the cantilever.",
        "positive": "Band Engineering in Cooper-Pair Box: Dispersive Measurements of Charge\n  and Phase: Low-frequency susceptibility of the split Cooper-pair box (SCPB) is\ninvestigated for use in sensitive measurements of external phase or charge.\nDepending on the coupling scheme, the box appears as either inductive or\ncapacitive reactance which depends on external phase and charge. While coupling\nto the source-drain phase, we review how the SCPB looks like a tunable\ninductance, which property we used to build a novel radio-frequency\nelectrometer. In the dual mode of operation, that is, while observed at the\ngate input, the SCPB looks like a capacitance. We concentrate on discussing the\nlatter scheme, and we show how to do studies of fast phase fluctuations at a\nsensitivity of 1 mrad/$\\sqrt{Hz}$ by measuring the input capacitance of the\nbox."
    },
    {
        "anchor": "Thouless pumping in Josephson junction arrays: Recent advancements in fabrication techniques have enabled unprecedented\nclean interfaces and gate tunability in semiconductor-superconductor\nheterostructures. Inspired by these developments, we propose protocols to\nrealize Thouless quantum pumping in electrically tunable Josephson junction\narrays. We analyze, in particular, the implementation of the Rice-Mele and the\nHarper-Hofstadter pumping schemes, whose realization would validate these\nsystems as flexible platforms for quantum simulations. We investigate\nnumerically the long-time behavior of chains of controllable superconducting\nislands in the Coulomb-blockaded regime. Our findings provide new insights into\nthe dynamics of periodically driven interacting systems and highlight the\nrobustness of Thouless pumping with respect to boundary effects typical of\nsuperconducting circuits.",
        "positive": "Quantum Spin Hall-like Phononic States in van der Waals Bilayers with\n  Antiferromagnetic Ordering: Here, we propose quantum spin Hall-like phononic states in van der Waals\nbilayer systems with antiferromagnetic ordering. Antiferromagnetic ordering in\nbilayer systems with small interlayer interaction makes the total Chern number\nzero, where the Chern numbers for each layer are opposite to each other. In\nbilayer CrI3 where antiferromagnetic ordering has been experimentally\ndemonstrated, we show that the quantum spin Hall-like states appear with\nspatially separated chiral edge modes."
    },
    {
        "anchor": "Leapfrogging vortex rings in the Landau-Lifshitz equation: Vortex rings are ubiquitous in fluids, with smoke rings being a familiar\nexample. The interaction of multiple vortex rings produces complex dynamical\nbehaviour, such as the leapfrogging motion first analysed by Helmholtz more\nthan a century and a half ago. Here we report on numerical investigations of\nvortex ring dynamics in a different setting from fluids, namely, as solutions\nof the Landau-Lifshitz equation that models the evolution of the local\nmagnetization in a ferromagnetic medium. We present the results of the first\nstudy on the dynamics of interacting magnetic vortex rings and provide a novel\nlink between fluids and magnetism, by showing that a range of phenomena\nfamiliar in fluids are reproduced in ferromagnets. This includes the\nleapfrogging motion of a pair of vortex rings and evidence for the chaotic\ndynamics of a trio of rings.",
        "positive": "Efficient quantum circuits for one-way quantum computing: While Ising-type interactions are ideal for implementing controlled phase\nflip gates in one-way quantum computing, natural interactions between\nsolid-state qubits are most often described by either the XY or the Heisenberg\nmodels. We show an efficient way of generating cluster states directly using\neither the iSWAP gate for the XY model, or the $\\sqrt{\\rm SWAP}$ gate for the\nHeisenberg model. Our approach thus makes one-way quantum computing more\nfeasible for solid-state devices."
    },
    {
        "anchor": "Manipulating quantum coherence of charge states in interacting\n  double-dot Aharonov-Bohm interferometers: We investigate the dynamics of charge--states coherence in a degenerate\ndouble--dot Aharonov--Bohm interferometer with finite interdot Coulomb\ninteractions. The quantum coherence of the charge states is found to be\nsensitive to the transport setup configurations, involving both the\nsingle--electron impurity channels and the Coulomb--assisted ones. We\nnumerically demonstrate the emergence of a complete coherence between the two\ncharge states, with the relative phase being continuously controllable through\nthe magnetic flux. Remarkably, a fully coherent charge qubit arises at the\ndouble--dots electron pair tunneling resonance condition, where the chemical\npotential of one electrode is tuned at the center between a single--electron\nimpurity channel and the related Coulomb--assisted channel. This pure quantum\nstate of charge qubit could be \\emph{experimentally located} at the\ncurrent--voltage characteristic turnover position, where differential\nconductance sign changes. We further elaborate the underlying mechanism for\nboth the real--time and the stationary charge--states coherences in the\ndouble--dot systems of study.",
        "positive": "A thermokinetic approach to radiative heat transfer at the nanoscale: Radiative heat exchange at the nanoscale presents a challenge for several\nareas due to its scope and nature. Here, we provide a thermokinetic description\nof microscale radiative energy transfer including phonon-photon coupling\nmanifested through a non-Debye relaxation behavior. We show that a\nlognormal-like distribution of modes of relaxation accounts for this non-Debye\nrelaxation behavior leading to the thermal conductance. We also discuss the\nvalidity of the fluctuation-dissipation theorem. The general expression for the\nthermal conductance we obtain fits existing experimental results with\nremarkable accuracy. Accordingly, our approach offers an overall explanation of\nradiative energy transfer through micrometric gaps regardless of geometrical\nconfigurations and distances."
    },
    {
        "anchor": "Instabilities of the AA-stacked graphene bilayer: Tight-binding calculations predict that the AA-stacked graphene bilayer has\none electron and one hole conducting bands, and that the Fermi surfaces of\nthese bands coincide. We demonstrate that as a result of this degeneracy, the\nbilayer becomes unstable with respect to a set of spontaneous symmetry\nviolations. Which of the symmetries is broken depends on the microscopic\ndetails of the system. We find that antiferromagnetism is the more stable order\nparameter. This order is stabilized by the strong on-site Coulomb repulsion.\nFor an on-site repulsion energy typical for graphene systems, the\nantiferromagnetic gap can exist up to room temperatures.",
        "positive": "Feedback Control of Waiting Times: Feedback loops are known as a versatile tool for controlling transport in\nsmall systems, which usually have large intrinsic fluctuations. Here we\ninvestigate the control of a temporal correlation function, the waiting time\ndistribution, under active and passive feedback conditions. We develop a\ngeneral formalism and then specify to the simple unidirectional transport\nmodel, where we compare costs of open loop and feedback control and use methods\nfrom optimal control theory to optimize waiting time distributions."
    },
    {
        "anchor": "Hydrodynamic theory of coupled current and magnetization dynamics in\n  spin-textured ferromagnets: We develop the hydrodynamical theory of collinear spin currents coupled to\nmagnetization dynamics in metallic ferromagnets. The collective spin density\ncouples to the spin current through a U(1) Berry-phase gauge field determined\nby the local texture and dynamics of the magnetization. We determine\nphenomenologically the dissipative corrections to the equation of motion for\nthe electronic current, which consist of a dissipative spin-motive force\ngenerated by magnetization dynamics and a magnetic texture-dependent\nresistivity tensor. The reciprocal dissipative, adiabatic spin torque on the\nmagnetic texture follows from the Onsager principle. We investigate the effects\nof thermal fluctuations and find that electronic dynamics contribute to a\nnonlocal Gilbert damping tensor in the Landau-Lifshitz-Gilbert equation for the\nmagnetization. Several simple examples, including magnetic vortices, helices,\nand spirals, are analyzed in detail to demonstrate general principles.",
        "positive": "Resolving the Topological Classification of Bismuth with Topological\n  Defects: Bulk boundary correspondence in topological materials allows to study their\nbulk topology through the investigation of their topological boundary modes.\nHowever, for classes that share similar boundary phenomenology, the growing\ndiversity of topological phases may lead to ambiguity in the topological\nclassification of materials. Such is the current status of bulk bismuth. While\nsome theoretical models indicate that bismuth possesses a trivial topological\nnature, other theoretical and experimental studies suggest non-trivial\ntopological classifications such as a strong or a higher order topological\ninsulator, both of which hosts helical modes on their boundaries. Here we use a\nnovel approach to resolve the topological classification of bismuth by\nspectroscopically mapping the response of its boundary modes to a topological\ndefect in the form of a screw dislocation (SD). We find that the edge mode\nextends over a wide energy range, and withstands crystallographic\nirregularities, without showing any signs of backscattering. It seems to bind\nto the bulk SD, as expected for a topological insulator (TI) with non-vanishing\nweak indices. We argue that the small scale of the bulk energy gap, at the time\nreversal symmetric momentum $L$, positions bismuth within the critical region\nof a topological phase transition to a strong TI with non-vanishing weak\nindices. We show that the observed boundary modes are approximately helical\nalready on the $\\mathbb{Z}_2$ trivial side of the topological phase transition.\nThis work opens the door for further possibilities to examine the response of\ntopological phases to crystallographic topological defects, and to uniquely\nexplore their associated bulk boundary phenomena."
    },
    {
        "anchor": "Composite metamaterials with dual-band magnetic resonances in the\n  terahertz frequency regime: Composite metamaterials(CMMs) combining a subwavelength metallic hole array\n(i.e. one-layer fishnet structure) and an array of split-ring resonators(SRRs)\non the same board are fabricated with gold films on silicon wafer. Transmission\nmeasurements of the CMMs in the terahertz range have been performed. Dual-band\nmagnetic resonances, namely, a LC resonance at 4.40 THz and an additional\nmagnetic resonance at 8.64 THz originating from the antiparallel current in\nwire pairs in the CMMs are observed when the electrical field polarization of\nthe incident light is parallel to the gap of the component SRR. The numerical\nsimulations agree well with the experimental results and further clarify the\nnature of the dual-band magnetic resonances.",
        "positive": "Unconventional superconductivity in nearly flat bands in twisted bilayer\n  graphene: Flat electronic bands can accommodate a plethora of interaction driven\nquantum phases, since kinetic energy is quenched therein and electronic\ninteractions therefore prevail. Twisted bilayer graphene, near so-called the\n\"magic angles\", features \\emph{slow} Dirac fermions close to the\ncharge-neutrality point that persist up to high-energies. Starting from a\ncontinuum model of slow, but strongly interacting Dirac fermions, we show that\nwith increasing chemical doping away from the charge-neutrality point, a\ntime-reversal symmetry breaking, valley pseudo-spin-triplet, topological $p+ip$\nsuperconductor gradually sets in, when the system resides at the brink of an\nanti-ferromagnetic ordering (due to Hubbard repulsion), in qualitative\nagreement with recent experimental findings. The $p+ip$ paired state exhibits\nquantized spin and thermal Hall conductivities, polar Kerr and Faraday\nrotations. Our conclusions should also be applicable for other correlated\ntwo-dimensional Dirac materials."
    },
    {
        "anchor": "Green's function methods for single molecule junctions: We present a brief pedagogical review of theoretical Green's function methods\napplicable to open quantum systems out of equilibrium in general, and single\nmolecule junctions in particular. We briefly describe experimental advances in\nmolecular electronics, then discuss different theoretical approaches. We then\nfocus on Green's function methods. Two characteristic energy scales governing\nthe physics are many-body interactions within the junctions, and\nmolecule-contact coupling. We therefore discuss weak interactions and weak\ncoupling, as two limits that can be conveniently treated within, respectively,\nthe standard nonequilibrium Green's function (NEGF) method and its many-body\nflavors (pseudoparticle and Hubbard NEGF). We argue that the intermediate\nregime, where the two energy scales are comparable, can in many cases be\nefficiently treated within the recently introduced superperturbation dual\nfermion approach. Finally, we review approaches for going beyond these\nanalytically accessible limits, as embodied by recent developments in\nnumerically exact methods based on Green's functions.",
        "positive": "All-electric detectors of the polarization state of terahertz laser\n  radiation (extended version): Two types of room temperature detectors of terahertz laser radiation have\nbeen developed which allow in an all-electric manner to determine the plane of\npolarization of linearly polarized radiation and the ellipticity of\nelliptically polarized radiation, respectively. The operation of the detectors\nis based on photogalvanic effects in semiconductor quantum well structures of\nlow symmetry. The photogalvanic effects have sub-nanosecond time constants at\nroom temperature making a high time resolution of the polarization detectors\npossible."
    },
    {
        "anchor": "Switching of Magnetic Moments of Nanoparticles by Surface Acoustic Waves: We report evidence of the magnetization reversal in nanoparticles by surface\nacoustic waves (SAWs). The experimental system consists of isolated magnetite\nnanoparticles dispersed on a piezoelectric substrate. Magnetic relaxation from\na saturated state becomes significantly enhanced in the presence of the SAW at\na constant temperature of the substrate. The dependence of the relaxation on\nSAW power and frequency has been investigated. The effect is explained by the\neffective ac magnetic field generated by the SAW in the nanoparticles.",
        "positive": "Temperature-tunable semiconductor metamaterial: We propose a novel class of temperature-tunable semiconductor metamaterials\nthat exhibit negative refraction in the terahertz spectral range. These\nmetamaterials are based on doped semiconductor superlattices with ultrathin\nbarriers of about 1 nm thickness. Due to the tunnel transparency of the\nbarriers, layers of the superlattice cannot be considered as isolated and,\ntherefore, the classical homogenization approach is inapplicable. We develop a\ntheory of quantum homogenization which is based on the Kubo formula for\nconductivity. The proposed approach takes into account the wave functions of\nthe carriers, their distribution function and energy spectrum. We show that the\ncomponents of the dielectric tensor of the semiconductor metamaterial can be\nefficiently manipulated by external temperature and a topological transition\nfrom the dielectric to hyperbolic regime of metamaterial can be observed at\nroom temperature. Using a GaAs/Al$_{0.3}$Ga$_{0.7}$As superlattice slab as an\nexample, we provide a numerical simulation of an experiment which shows that\nthe topological transition can be observed in the reflection spectrum from the\nslab."
    },
    {
        "anchor": "Plasmon Spectrum of Single Layer Antimonene: The collective excitation spectrum of two-dimensional (2D) antimonene is\ncalculated beyond the low energy continuum approximation. The dynamical\npolarizability is computed using a 6-orbitals tight-binding model that properly\naccounts for the band structure of antimonene in a broad energy range.\nElectron-electron interaction is considered within the random phase\napproximation. The obtained spectrum is rich, containing the standard\nintra-band 2D plasmon and a set of single inter-band modes. We find that\nspin-orbit interaction plays a fundamental role in the reconstruction of the\nexcitation spectrum, with the emergence of novel inter-band branches in the\ncontinuum that interact with the plasmon.",
        "positive": "Through-membrane electron-beam lithography for ultrathin membrane\n  applications: We present a technique to fabricate ultrathin (down to 20 nm) uniform\nelectron transparent windows at dedicated locations in a SiN membrane for in\nsitu transmission electron microscopy experiments. An electron-beam (e-beam)\nresist is spray-coated on the backside of the membrane in a KOH- etched cavity\nin silicon which is patterned using through-membrane electron-beam lithography.\nThis is a controlled way to make transparent windows in membranes, whilst the\ntopside of the membrane remains undamaged and retains its flatness. Our\napproach was optimized for MEMS-based heating chips but can be applied to any\nchip design. We show two different applications of this technique for (1)\nfabrication of a nanogap electrode by means of electromigration in thin\nfree-standing metal films and (2) making low-noise graphene nanopore devices."
    },
    {
        "anchor": "Entangling spin and charge degrees of freedom in semiconductor quantum\n  dots: In this theoretical manuscript I propose a scheme for entangling a single\nelectron semiconductor spin qubit with a single electron semiconductor charge\nqubit in a triangular triple quantum dot configuration. Two out of three\nquantum dots are used to define a single electron semiconductor charge qubit.\nFurthermore, the spin qubit is embedded in the Zeeman sub-levels of the third\nquantum dot. Combining single qubit gates with entangling CNOT gates allows one\nto construct a SWAP gate, and therefore to use the semiconductor spin qubit as\na long-lived memory for the semiconductor charge qubit.",
        "positive": "Magnetic near fields as a probe of charge transport in spatially\n  dispersive conductors: We calculate magnetic field fluctuations above a conductor with a nonlocal\nresponse (spatial dispersion) and consider a large range of distances. The\ncross-over from ballistic to diffusive charge transport leads to reduced noise\nspectrum at distances below the electronic mean free path, as compared to a\nlocal description. We also find that the mean free path provides a lower limit\nto the correlation (coherence) length of the near field fluctuations. The\nshort-distance behavior is common to a wide range of materials, covering also\nsemiconductors and superconductors. Our discussion is aimed at atom chip\nexperiments where spin-flip transitions give access to material properties with\nmesoscopic spatial resolution. The results also hint at fundamental limits to\nthe coherent operation of miniaturized atom traps and matter wave\ninterferometers."
    },
    {
        "anchor": "Magnetic quantum oscillations in nanowires: Analytical expressions for the magnetization and the longitudinal\nconductivity of nanowires are derived in a magnetic field, B. We show that the\ninterplay between size and magnetic field energy-level quantizations manifests\nitself through novel magnetic quantum oscillations in metallic nanowires. There\nare three characteristic frequencies of de Haas-van Alphen (dHvA) and\nShubnikov-de Haas (SdH) oscillations, F=F_0,F_1, and F_2 in contrast with a\nsingle frequency F'_0 in simple bulk metals. The amplitude of oscillations is\nstrongly enhanced in some \"magic\" magnetic fields. The wire cross-section S can\nbe measured along with the Fermi surface cross-section, S_F.",
        "positive": "Novel characterisation of dopant-based qubits: Silicon is a leading qubit platform thanks to the exceptional coherence times\nthat can be achieved and to the available commercial manufacturing platform for\nintegration. Building scalable quantum processing architectures relies on\naccurate quantum state manipulation, which can only be achieved through a\ncomplete understanding of the underlying quantum state properties. This article\nreviews the electrical methods that have been developed to probe the quantum\nstates encoded in individual and interacting atom qubits in silicon, from the\npioneering single electron tunneling spectroscopy framework in nanoscale\ntransistors, to radio frequency reflectometry to probe coherence properties and\nscanning tunneling microscopy to directly image the wave function at the atomic\nscale. Together with the development of atomistic simulations of realistic\ndevices, these methods are today applied to other emerging dopant and optically\naddressable defect states to accelerate the engineering of quantum technologies\nin silicon."
    },
    {
        "anchor": "Spin Transfer Torque Generated by the Topological Insulator Bi_2Se_3: Magnetic devices are a leading contender for implementing memory and logic\ntechnologies that are nonvolatile, that can scale to high density and high\nspeed, and that do not suffer wear-out. However, widespread applications of\nmagnetic memory and logic devices will require the development of efficient\nmechanisms for reorienting their magnetization using the least possible current\nand power. There has been considerable recent progress in this effort, in\nparticular discoveries that spin-orbit interactions in heavy metal/ferromagnet\nbilayers can yield strong current-driven torques on the magnetic layer, via the\nspin Hall effect in the heavy metal or the Rashba-Edelstein effect in the\nferromagnet. As part of the search for materials to provide even more efficient\nspin-orbit-induced torques, some proposals have suggested topological\ninsulators (TIs), which possess a surface state in which the effects of\nspin-orbit coupling are maximal in the sense that an electron's spin\norientation is locked relative to its propagation direction. Here we report\nexperiments showing that charge current flowing in-plane in a thin film of the\nTI Bi_2Se_3 at room temperature can indeed apply a strong spin-transfer torque\nto an adjacent ferromagnetic permalloy (Py = Ni81Fe19) thin film, with a\ndirection consistent with that expected from the topological surface state. We\nfind that the strength of the torque per unit charge current density in the\nBi_2Se_3 is greater than for any other spin-torque source material measured to\ndate, even for non-ideal TI films wherein the surface states coexist with bulk\nconduction. Our data suggest that TIs have potential to enable very efficient\nelectrical manipulation of magnetic materials at room temperature for memory\nand logic applications.",
        "positive": "Goos-Hanchen shift of a spin-wave beam transmitted through anisotropic\n  interface between two ferromagnets: The main object of investigation in magnonics, spin waves (SWs) are promising\ninformation carriers. Presently the most commonly studied are plane wave-like\nSWs and SWs propagating in confined structures, such as waveguides. Here we\nconsider a Gaussian SW beam obliquely incident on an ultra-narrow interface\nbetween two identical ferromagnetic materials. We use an analytical model and\nmicromagnetic simulations for an in-depth analysis of the influence of the\ninterface properties, in particular the magnetic anisotropy, on the\ntransmission of the SW beam. We derive analytical formulas for the reflectance,\ntransmittance, phase shift and Goos-Hanchen (GH) shift for beams reflected and\nrefracted by an interface between two semi-infinite ferromagnetic media; the\nresults for the refracted beam are the first to be reported to date. The GH\nshifts in SW beam reflection and transmission are confirmed by micromagnetic\nsimulations in the thin-film geometry. We demonstrate the dependence of the\ncharacteristic properties on the magnetic anisotropy at the interface, the\nangle of incidence and the frequency of the SWs. We also propose a method for\nthe excitation of high-quality SW beams in micromagnetic simulations."
    },
    {
        "anchor": "Quantized Topological Charges of Ferroelectric Skyrmions in\n  Two-Dimensional Multiferroic Materials: In multiferroic materials, the microscopic magnetic and electric textures are\nstrongly correlated with each other by magnetoelectric (ME) coupling.\nTherefore, topological electric dipole textures, such as ferroelectric (FE)\ndipole skyrmions and periodic FE dipole crystals, are expected to be induced if\nferromagnetic (FM) skyrmions and FM skyrmionic crystals (or lattices so as to\nbe abbreviated as SLs for convenience) can be stabilized. In the present work,\na quantum computational approach is utilized to simulate the topological\ntextures of FE SLs in a two-dimensional (2D) multiferroic system. Consequently,\nwe find that, FE SLs can indeed be induced once the FM SLs are formed; each FE\nskyrmion is an ferroelectric dipolar complex formed around an FM skyrmion; the\ntopological charges of these FE skyrmions are usually quantized to be integers,\nhalf integers and multiples of certain fractional values, so that the FE SL\ncoincides precisely with the corresponding FM SL; the topological charge\ndensity of each FE SL also forms periodic pattern; and a normally applied\nelectric field is able to change the sizes of FM skyrmions, elevate their\nformation temperatures, and destroy FM SLs below the critical temperatures.",
        "positive": "Quantum disordering of the 111 state and the compressible-incompressible\n  transition in quantum Hall bilayer systems: We systematically discuss properties of quantum disordered states of the\nquantum Hall bilayer at \\nu_T = 1. For one of them, so-called vortex metal\nstate, we find ODLRO (off-diagonal long-range order) of algebraic kind, and\nderive its transport properties. It is shown that this state is relevant for\nthe explanation of the \"imperfect\" superfluid behavior, and persistent\nintercorrelations, for large distances between layers, that were found in\nexperiments."
    },
    {
        "anchor": "Introduction to Quantum Noise, Measurement and Amplification: The topic of quantum noise has become extremely timely due to the rise of\nquantum information physics and the resulting interchange of ideas between the\ncondensed matter and AMO/quantum optics communities. This review gives a\npedagogical introduction to the physics of quantum noise and its connections to\nquantum measurement and quantum amplification. After introducing quantum noise\nspectra and methods for their detection, we describe the basics of weak\ncontinuous measurements. Particular attention is given to treating the standard\nquantum limit on linear amplifiers and position detectors using a general\nlinear-response framework. We show how this approach relates to the standard\nHaus-Caves quantum limit for a bosonic amplifier known in quantum optics, and\nillustrate its application for the case of electrical circuits, including\nmesoscopic detectors and resonant cavity detectors.",
        "positive": "Vibrational excitation mechanism in tunneling spectroscopy beyond the\n  Franck-Condon model: Vibronic spectra of molecules are typically described within the\nFranck-Condon model. Here, we show that highly resolved vibronic spectra of\nlarge organic molecules on a single layer of MoS$_{2}$ on Au(111) show spatial\nvariations in their intensities, which cannot be captured within this picture.\nWe explain that vibrationally mediated perturbations of the molecular wave\nfunctions need to be included into the Franck-Condon model. Our simple model\ncalculations reproduce the experimental spectra at arbitrary position of the\nSTM tip over the molecule in great detail."
    },
    {
        "anchor": "Resonant tunneling of interacting electrons in a one-dimensional wire: We consider the conductance of a one-dimensional wire interrupted by a\ndouble-barrier structure allowing for a resonant level. Using the\nelectron-electron interaction strength as a small parameter, we are able to\nbuild a non-perturbative analytical theory of the conductance valid in a broad\nregion of temperatures and for a variety of the barrier parameters. We find\nthat the conductance may have a non-monotonic crossover dependence on\ntemperature, specific for a resonant tunneling in an interacting electron\nsystem.",
        "positive": "Quantum Dots Attached to Ferromagnetic Leads: Exchange Field, Spin\n  Precession, and Kondo Effect: Spintronics devices rely on spin-dependent transport behavior evoked by the\npresence of spin-polarized electrons. Transport through nanostructures, on the\nother hand, is dominated by strong Coulomb interaction. We study a model system\nin the intersection of both fields, a quantum dot attached to ferromagnetic\nleads. The combination of spin-polarization in the leads and strong Coulomb\ninteraction in the quantum dot gives rise to an exchange field acting on\nelectron spins in the dot. Depending on the parameter regime, this exchange\nfield is visible in the transport either via a precession of an accumulated dot\nspin or via an induced level splitting. We review the situation for various\ntransport regimes, and discuss two of them in more detail."
    },
    {
        "anchor": "Zero modes and the edge states of the honeycomb lattice: The honeycomb lattice in the cylinder geometry with zigzag edges, bearded\nedges, zigzag and bearded edges (zigzag-bearded), and armchair edges are\nstudied. The tight-binding model with nearest-neighbor hoppings is used. Edge\nstates are obtained analytically for these edges except the armchair edges. It\nis shown, however, that edge states for the armchair edges exist when the the\nsystem is anisotropic. These states have not been known previously. We also\nfind strictly localized states, uniformly extended states and states with\nmacroscopic degeneracy.",
        "positive": "Linearity of the edge states energy spectrum in the 2D topological\n  insulator: Linearity of the topological insulator edge state spectrum plays the crucial\nrole for various transport phenomena. The previous studies found that this\nlinearity exists near the spectrum crossing point, but did not determine how\nperfect the linearity is. The purpose of the present study is to answer this\nquestion in various edge states models. We examine Volkov and Pankratov (VP)\nmodel [1] for the Dirac Hamiltonian and the model of [2,3] (BHZ1) for the\nBernevig, Hughes and Zhang (BHZ) Hamiltonian [4] with zero boundary conditions.\nIt is found that both models yield ideally linear edge states. In the BHZ1\nmodel the linearity is conserved up to the spectrum ending points corresponding\nto the tangency of the edge spectrum with the boundary of 2D states. In\ncontrast, the model of[5] (BHZ2) with mixed boundary conditions for BHZ\nHamiltonian and the 2D tight-binding (TB) model from [4] yield weak\nnon-linearity."
    },
    {
        "anchor": "Resonant Tunneling in Truly Axial Symmetry Mn12 Single-Molecule Magnets:\n  Sharp Crossover between Thermally Assisted and Pure Quantum Tunneling: Magnetization measurements of a truly axial symmetry Mn12-tBuAc molecular\nnanomagnet with a spin ground state of S = 10 show resonance tunneling. This\ncompound has the same magnetic anisotropy as Mn12-Ac but the molecules are\nbetter isolated and the crystals have less disorder and a higher symmetry.\nHysteresis loop measurements at several temperatures reveal a well-resolved\nstep fine-structure which is due to level crossings of excited states. All step\npositions can be modeled by a simple spin Hamiltonian. The crossover between\nthermally assisted and pure quantum tunneling can be investigated with\nunprecedented detail.",
        "positive": "Tensor network trial states for chiral topological phases in two\n  dimensions and a no-go theorem in any dimension: Trial wavefunctions that can be represented by summing over locally-coupled\ndegrees of freedom are called tensor network states (TNSs); they have seemed\ndifficult to construct for two-dimensional topological phases that possess\nprotected gapless edge excitations. We show it can be done for chiral states of\nfree fermions, using a Gaussian Grassmann integral, yielding $p_x \\pm i p_y$\nand Chern insulator states, in the sense that the fermionic excitations live in\na topologically non-trivial bundle of the required type. We prove that any\nstrictly short-range quadratic parent Hamiltonian for these states is gapless;\nthe proof holds for a class of systems in any dimension of space. The proof\nalso shows, quite generally, that sets of compactly-supported Wannier-type\nfunctions do not exist for band structures in this class. We construct further\nexamples of TNSs that are analogs of fractional (including non-Abelian) quantum\nHall phases; it is not known whether parent Hamiltonians for these are also\ngapless."
    },
    {
        "anchor": "Selection rules for Raman-active electronic excitations in carbon\n  nanotubes: Raman measurements in carbon allotropes are generally associated with the\nexploration of the vibrational modes. Here, we present a theory of the\nnon-resonant inelastic light scattering accompanied by the excitations of\nintersubband electron-hole pairs in carbon nanotubes and predict the selection\nrules and polarization properties of the dominant intersubband Raman active\nmodes.",
        "positive": "Coherent Particle Transfer in an On-Demand Single-Electron Source: Coherent electron transfer from a localized state trapped in a quantum dot\ninto a ballistic conductor, taking place in on-demand electron sources, in\ngeneral may result in excitation of particle-hole pairs. We consider a simple\nmodel for these effects, involving a resonance level with time-dependent\nenergy, and derive Floquet scattering matrix describing inelastic transitions\nof particles in the Fermi sea. We find that, as the resonance level is driven\nthrough the Fermi level, particle transfer may take place completely without\nparticle-hole excitations for certain driving protocols. In particular, such\nnoiseless transfer occurs when the level moves with constant rapidity, its\nenergy changing linearly with time. A detection scheme for studying the\ncoherence of particle transfer is proposed."
    },
    {
        "anchor": "Scaling properties of induced density of chiral and non-chiral Dirac\n  fermions in magnetic fields: We find that a repulsive potential of graphene in the presence of a magnetic\nfield has bound states that are peaked inside the barrier with tails extending\nover \\ell(N + 1), where \\ell and N are the magnetic length and Landau level(LL)\nindex. We have investigated how these bound states affect scaling properties of\nthe induced density of filled Landau levels of massless Dirac fermions. For\nchiral fermions we find, in strong coupling regime, that the density inside the\nrepulsive potential can be greater than the value in the absence of the\npotential while in the weak coupling regime we find negative induced density.\nSimilar results hold also for non-chiral fermions. As one moves from weak to\nstrong coupling regimes the effective coupling constant between the potential\nand electrons becomes more repulsive, and then it changes sign and becomes\nattractive. Different power-laws of induced density are found for chiral and\nnon-chiral fermions.",
        "positive": "Non-Reciprocal Geometric Wave Diode by Engineering Asymmetric Shapes of\n  Nonlinear Materials: Unidirectional nonreciprocal transport is at the heart of many fundamental\nproblems and applications in both science and technology. Here we study the\nnovel design of wave diode devices by engineering asymmetric shapes of\nnonlinear materials to realize the function of non-reciprocal wave\npropagations. We first show analytical results revealing that both nonlinearity\nand asymmetry are necessary to induce such non-reciprocal (asymmetric) wave\npropagations. Detailed numerical simulations are further performed for a more\nrealistic geometric wave diode model with typical asymmetric shape, where good\nnon-reciprocal wave diode effect is demonstrated. Finally, we discuss the\nscalability of geometric wave diodes. The results open a flexible way for\ndesigning wave diodes efficiently simply through shape engineering of nonlinear\nmaterials, which may find broad implications in controlling energy, mass and\ninformation transports."
    },
    {
        "anchor": "Atomic Structure of Hematite ($\u03b1$-Fe$_2$O$_3$) Nanocube Surface;\n  Synchrotron X-ray Diffraction Study: Atomic structure of a mono-dispersive hematite ($\\alpha$-Fe$_2$O$_3$)\nnanocube $(0 1\\bar1 2)$ surface was determined with synchrotron X-ray\ndiffraction. The $\\alpha$-Fe$_2$O$_3$ nanocubes were prepared through a\nhydrothermal process and a single layer of nanocubes was deposited on a silicon\nsubstrate with a drop cast method. The alignment of nanocubes with their $(0\n1\\bar1 2)$ surfaces parallel to the substrate is confirmed with grazing\nincidence X-ray diffraction. Specular crystal truncation rods (CTR's) from\nas-prepared and vacuum annealed nanocube surfaces have been measured and they\nare drastically different from previously reported CTR's from macroscopic\nsingle crystal $(0 1\\bar1 2)$ surfaces. The measured CTR's from nanocube\nsurfaces are explained well with the atomic structure models of half of atoms\nin top Fe layer being missing while extra oxygen-layers cover the half-missing\nFe layer. An acidic environment during hydrothermal nanocube synthesis process\nis proposed as the main cause of the difference.",
        "positive": "Role of molecular electronic structure in IETS: the case of O_2 on\n  Ag(110): Density functional theory (DFT) simulations corrected by the intramolecular\nCoulomb repulsion U, are performed to evaluate the vibrational inelastic\nelectron tunneling spectroscopy (IETS) of O_2 molecules on Ag(110). Semilocal\nDFT calculations predict a spinless adsorbed molecule, however the inclusion of\nthe U leads to the polarization of the molecule by shifting a spin-polarized\nmolecular orbital towards the Fermi level. A molecular resonance at the Fermi\nlevel can imply a decrease in conductance while in the off-resonance case, an\nincrease in conductance is the expected IETS signal. We use the lowest-order\nexpansion on the electron-vibration coupling, in order to evaluate the\nmagnitude and spatial distribution of the inelastic signal. This allows us to\nreproduce the experimental data in: (i) the negative conductance variation\nobserved in the vibrational spectra of O_2 along the [001] direction, (ii) the\nspatial distribution of the conductance changes recorded over the O_2 molecule\nfor the O--O stretch and the antisymmetric O_2--Ag stretch vibrations, (iii)\nthe absence of signal for the center-of-mass and hindered rotations modes, and\n(iv) the lack of IETS signal for the molecule chemisorbed along the [1-10]\ndirection. Moreover, our results give us insight of the electronic and\nvibrational symmetries at play. The vibrational frequencies need to go beyond\nthe harmonic approximation in order to be compared with the experimental ones,\nhence we present a Morse-potential fitting of the potential energy surface in\norder to evaluate accurate vibrational frequencies. The final IET spectra are\nevaluated with the help of the self-consistent Born Approximation and the\neffect of temperature and modulation-voltage broadening are explored. This\nensemble of results reveals that the IETS of O_2 cannot be ascribed to the\neffect of a single orbital molecular resonance."
    },
    {
        "anchor": "Trion resonance in polariton-electron scattering: Strong interactions between charges and light-matter coupled quasiparticles\noffer an intriguing prospect with applications from optoelectronics to\nlight-induced superconductivity. Here, we investigate how the interactions\nbetween electrons and exciton-polaritons in a two-dimensional semiconductor\nmicrocavity can be resonantly enhanced due to a strong coupling to a trion,\ni.e., an electron-exciton bound state. We develop a microscopic theory that\nuses a strongly screened interaction between charges to enable the summation of\nall possible diagrams in the polariton-electron scattering process. The\nposition and magnitude of the resonance is found to vary depending on the\nvalues of the light-matter coupling and detuning, thus indicating a large\ndegree of tunability. We furthermore derive an analytic approximation of the\ninteraction strength based on universal lowenergy scattering theory. This is\nfound to match extremely well with our full calculation, indicating that the\ntrion resonance is near universal, depending more on the strength of the\nlight-matter coupling relative to the trion binding energy rather than on the\ndetails of the electronic interactions. Thus, we expect the trion resonance in\npolariton-electron scattering to appear in a broad range of microcavity systems\nwith few semiconductor layers, such as doped monolayer MoSe2 where such\nresonances have recently been observed experimentally [Sidler et al., Nature\nPhysics 13, 255 (2017)].",
        "positive": "Cs adsorption on Bi$_2$Se$_3$: Bi$_2$Se$_3$ is a topological insulator whose unique properties result from\ntopological surface states (TSS) in the band gap. The adsorption of Cs onto a\nBi$_2$Se$_3$ surface is investigated by low energy ion scattering and work\nfunction measurements. Much of the deposited Cs quickly diffuses to the step\nedges forming one-dimensional chains of positively charged adatoms, along with\nsome deposition on the terraces. The work function decreases until a coverage\nof 0.1 ML is reached, beyond which it increases slightly. The minimum in the\nwork function is due to depolarization of the dipoles induced when the\nconcentration of adatoms in the chains reaches a critical value. A slow\ndiffusion of adsorbed Cs from the terraces to the step edges is also marked by\nchanges in the neutralization of scattered Na$^+$ and work function over time.\nThe spatial distribution of the conductive charges in the TSS, which are\nprimarily positioned between the first and second atomic layers, is confirmed\nby comparison of the neutralization of Na$^+$ scattered from Bi and Se."
    },
    {
        "anchor": "Quantum transport through a double Aharonov-Bohm-interferometer in the\n  presence of Andreev reflection: Quantum transport through a double Aharonov-Bohm-interferometer in the\npresence of Andreev reflection is investigated in terms of the nonequilibrium\nGreen function method with which the reflection current is obtained. Tunable\nAndreev reflection probabilities depending on the interdot coupling strength\nand magnetic flux as well are analysised in detail. It is found that the\noscillation period of the reflection probability with respect to the magnetic\nflux for the double interferometer depends linearly on the ratio of two parts\nmagnetic fluxes n, i.e. 2(n+1)pi, while that of a single interferometer is 2pi.\nThe coupling strength not only affects the height and the linewidth of Andreev\nreflection current peaks vs gate votage but also shifts the peak positions. It\nis furthermore demonstrated that the Andreev reflection current peaks can be\ntuned by the magnetic fluxes.",
        "positive": "Phase diagram for condensation of microcavity polaritons: from theory to\n  practice: The first realization of a polariton condensate was recently achieved in a\nCdTe microcavity [Kasprzak et al., Nature 443, 409 (2006)]. We compare the\nexperimental phase boundaries, for various detunings and cryostat temperatures,\nwith those found theoretically from a model which accounts for features of\nmicrocavity polaritons such as reduced dimensionality, internal composite\nstructure, disorder in the quantum wells, polariton-polariton interactions, and\nfinite lifetime."
    },
    {
        "anchor": "Breaking surface plasmon excitation constraint via surface spin waves: Surface plasmons in two-dimensional (2D) electron systems have attracted\ngreat attention for their promising light-matter applications. However, the\nexcitation of a surface plasmon, in particular, transverse-electric (TE)\nsurface plasmon, remains an outstanding challenge due to the difficulty to\nconserve energy and momentum simultaneously in the normal 2D materials. Here we\nshow that the TE surface plasmons ranging from gigahertz to terahertz regime\ncan be effectively excited and manipulated in a hybrid dielectric, 2D material\nand magnet structure. The essential physics is that the surface spin wave\nsupplements an additional freedom of surface plasmon excitation and thus\ngreatly enhances the electric field in the 2D medium. Based on widely-used\nmagnetic materials like yttrium iron garnet (YIG) and manganese difluoride\n($\\mathrm{MnF}_2$), we further show that the plasmon excitation manifests\nitself as a measurable dip in the reflection spectrum of the hybrid system\nwhile the dip position and the dip depth can be well controlled by the electric\ngating on the 2D layer and an external magnetic field. Our findings should\nbridge the fields of low-dimensional physics, plasmonics and spintronics and\nopen a novel route to integrate plasmonic and spintronic devices.",
        "positive": "Hybrid circuit cavity quantum electrodynamics with a micromechanical\n  resonator: Hybrid quantum systems with inherently distinct degrees of freedom play a key\nrole in many physical phenomena. Famous examples include cavity quantum\nelectrodynamics, trapped ions, or electrons and phonons in the solid state.\nHere, a strong coupling makes the constituents loose their individual character\nand form dressed states. Apart from fundamental significance, hybrid systems\ncan be exploited for practical purpose, noteworthily in the emerging field of\nquantum information control. A promising direction is provided by the\ncombination between long-lived atomic states and the accessible electrical\ndegrees of freedom in superconducting cavities and qubits. Here we integrate\ncircuit cavity quantum electrodynamics with phonons. Besides coupling to a\nmicrowave cavity, our superconducting transmon qubit interacts with a phonon\nmode in a micromechanical resonator, thus representing an atom coupled to two\ndifferent cavities. We measure the phonon Stark shift, as well as the splitting\nof the qubit spectral line into motional sidebands, which feature transitions\nbetween the dressed electromechanical states. In the time domain, we observe\ncoherent conversion of qubit excitation to phonons as sideband Rabi\noscillations. This is a model system having potential for a quantum interface,\nwhich may allow for storage of quantum information in long-lived phonon states,\ncoupling to optical photons, or for investigations of strongly coupled quantum\nsystems near the classical limit."
    },
    {
        "anchor": "High Electron Mobility in Epitaxial Graphene on 4H-SiC(0001) via\n  post-growth annealing under hydrogen: We investigate the magneto-transport properties of epitaxial graphene\nsingle-layer on 4H-SiC(0001), grown by atmospheric pressure graphitization in\nAr, followed by H2 intercalation. We directly demonstrate the importance of\nsaturating the Si dangling bonds at the graphene/SiC(0001) interface to achieve\nhigh carrier mobility. Upon successful Si dangling bonds elimination, carrier\nmobility increases from 3 000 cm^2/Vs to > 11 000 cm^2/Vs at 0.3 K.\nAdditionally, graphene electron concentration tends to decrease from a few\n10^12 cm^-2 to less than 10^12 cm^-2. For a typical large (30x280 um^2) Hall\nbar, we report the observation of the integer quantum Hall states at 0.3 K with\nwell developed transversal resistance plateaus at Landau level fillings factors\nof nu = 2, 6, 10, 14.. 42 and Shubnikov de Haas oscillation of the longitudinal\nresistivity observed from about 1 T. In such a device, the Hall state\nquantization at nu=2, at 19 T and 0.3 K, can be very robust: the dissipation in\nelectronic transport can stay very low, with the longitudinal resistivity lower\nthan 5 mOhm, for measurement currents as high as 250 uA. This is very promising\nin the view of an application in metrology.",
        "positive": "Electron spin relaxation as evidence of excitons in an electron-hole\n  plasma: We exploit the influence of the Coulomb interaction between electrons and\nholes on the electron spin relaxation in a (110)-GaAs quantum well to unveil\nexcitonic signatures within the many particle electron-hole system. The\ntemperature dependent time- and polarization-resolved photoluminescence\nmeasurements span five decades of carrier density, comprise the transition from\nlocalized excitons over quasi free excitons to an electron-hole plasma, and\nreveal strong excitonic signatures even at relatively high densities and\ntemperatures."
    },
    {
        "anchor": "Quasi-one-dimensional ballistic ring in crossed high-frequency electric\n  fields: We study electron dynamics in a quasi-one-dimensional ballistic ring driven\nby two crossed high-frequency electric fields parallel to the ring plane. The\naveraged dipole moment and emission intensity are calculated. The emission\npolarization coincides with the direction of one of the fields. A possibility\nis shown of the polarization switching to perpendicular direction under changes\nin the field amplitudes and frequencies.",
        "positive": "Chaotic dynamics in spin-vortex pairs: We report on spin-vortex pair dynamics measured at temperatures low enough to\nsuppress stochastic core motion, thereby uncovering the highly non-linear\nintrinsic dynamics of the system. Our analysis shows that the decoupling of the\ntwo vortex cores is resonant and can be enhanced by dynamic chaos. We detail\nthe regions of the relevant parameter space, in which the various mechanisms of\nthe resonant core-core dynamics are activated. We show that the presence of\nchaos can reduce the thermally-induced spread in the switching time by up to\ntwo orders of magnitude."
    },
    {
        "anchor": "Vortex core magnetization dynamics induced by thermal excitation: We investigate the effect of temperature on the dynamic properties of\nmagnetic vortices in small disks. Our calculations use a stochastic version of\nthe Landau-Lifshitz-Gilbert (LLG) equation, valid for finite temperatures well\nbelow the Curie critical temperature. We show that a finite temperature induces\na vortex precession around the center of the disk, even in the absence of other\nexcitation sources. We discuss the origin and implications of the appearance of\nthis new dynamics. We also show that a temperature gradient plays a role\nsimilar to that of a small constant magnetic field.",
        "positive": "Magic-angle Bilayer Phononic Graphene: Thanks to the recent discovery on the magic-angle bilayer graphene,\ntwistronics is quickly becom11 ing a burgeoning field in condensed matter\nphysics. This letter expands the realm of twistronics to acoustics by\nintroducing twisted bilayer phononic graphene, which remarkably also harbors\nthe magic angle, evidenced by the associated ultra-flat bands. Beyond mimicking\nquantum mechanical behaviors of twisted bilayer graphene, we show that their\nacoustic counterpart offers a considerably more straightforward and robust way\nto alter the interlayer hopping strength, enabling us to unlock magic angles (>\n3 degrees) inaccessible in classical twisted bilayer graphene. This study, not\nonly establishes the acoustical analog of twisted (magic-angle) bilayer\ngraphene, providing a testbed more easily accessible to probe the interaction\nand misalignment between stacked 2D materials, but also points out the\ndirection to a new phononic crystal design paradigm that could benefit\napplications such as enhanced acoustic emission and sensing."
    },
    {
        "anchor": "Quantum oscillations from generic surface Fermi arcs and bulk chiral\n  modes in Weyl semimetals: We re-examine the question of quantum oscillations from surface Fermi arcs\nand chiral modes in Weyl semimetals. By introducing two tools - semiclassical\nphase-space quantization and a numerical implementation of a layered\nconstruction of Weyl semimetals - we discover several important generalizations\nto previous conclusions that were implicitly tailored to the special case of\nidentical Fermi arcs on top and bottom surfaces. We show that the phase-space\nquantization picture fixes an ambiguity in the previously utilized energy-time\nquantization approach and correctly reproduces the numerically calculated\nquantum oscillations for generic Weyl semimetals with distinctly curved Fermi\narcs on the two surfaces. Based on these methods, we identify a 'magic'\nmagnetic-field angle where quantum oscillations become independent of sample\nthickness, with striking experimental implications. We also analyze the\nstability of these quantum oscillations to disorder, and show that the\nhigh-field oscillations are expected to persist in samples whose thickness\nparametrically exceeds the quantum mean free path.",
        "positive": "Anomalies in the conduction edge of quantum wires: We study the conductance threshold of clean nearly straight quantum wires in\nwhich an electron is bound. We show that such a system exhibits spin-dependent\nconductance structures on the rising edge to the first conductance plateau, one\nnear 0.25(2e^2/h), related to a singlet resonance, and one near 0.75(2e^2/h),\nrelated to a triplet resonance. As a quantitative example we solve exactly the\nscattering problem for two-electrons in a wire with circular cross-section and\na weak bulge. From the scattering matrix we determine conductance via the\nLandauer-Buettiker formalism. The conductance anomalies are robust and survive\nto temperatures of a few degrees. With increasing magnetic field the\nconductance exhibits a plateau at e^2/h, consistent with recent experiments."
    },
    {
        "anchor": "External field control of donor electron exchange at the Si/SiO2\n  interface: We analyze several important issues for the single- and two-qubit operations\nin Si quantum computer architectures involving P donors close to a SiO2\ninterface. For a single donor, we investigate the donor-bound electron\nmanipulation (i.e. 1-qubit operation) between the donor and the interface by\nelectric and magnetic fields. We establish conditions to keep a donor-bound\nstate at the interface in the absence of local surface gates, and estimate the\nmaximum planar density of donors allowed to avoid the formation of a\n2-dimensional electron gas at the interface. We also calculate the times\ninvolved in single electron shuttling between the donor and the interface. For\na donor pair, we find that under certain conditions the exchange coupling (i.e.\n2-qubit operation) between the respective electron pair at the interface may be\nof the same order of magnitude as the coupling in GaAs-based two-electron\ndouble quantum dots where coherent spin manipulation and control has been\nrecently demonstrated (for example for donors ~10 nm below the interface and\n\\~40 nm apart, J~10^{-4} meV), opening the perspective for similar experiments\nto be performed in Si.",
        "positive": "What is the best planar cavity for maximizing coherent exciton-photon\n  coupling: We compare alternative planar cavity structures for strong exciton$-$photon\ncoupling, where the conventional distributed Bragg reflector (DBR) and three\nunconventional types of cavity mirrors$-$ air/GaAs DBR, Tamm $-$ plasmon mirror\nand sub$-$wavelength grating mirror. We design and optimize the planar cavities\nbuilt with each type of mirror at one side or both sides for maximum vacuum\nfield strength. We discuss the trade$-$off between performance and fabrication\ndifficulty for each cavity structure. We show that cavities with\nsub$-$wavelength grating mirrors allow simultaneously strongest field and high\ncavity quality. The optimization principles and techniques developed in this\nwork will guide the cavity design for research and applications of\nmatter$-$light coupled semiconductors, especially new material systems that\nrequire greater flexibility in the choice of cavity materials and cavity\nfabrication procedures."
    },
    {
        "anchor": "A charge parity ammeter: A metallic double-dot is measured with radio frequency reflectometry. Changes\nin the total electron number of the double-dot are determined via single\nelectron tunnelling contributions to the complex electrical impedance. Electron\ncounting experiments are performed by monitoring the impedance, demonstrating\noperation of a single electron ammeter without the need for external charge\ndetection.",
        "positive": "Gate reflectometry for probing charge and spin states in linear Si MOS\n  split-gate arrays: We fabricated linear arrangements of multiple splitgate devices along an SOI\nmesa, thus forming a 2xN array of individually controllable Si quantum dots\n(QDs) with nearest neighbor coupling. We implemented two different gate\nreflectometry-based readout schemes to either probe spindependent charge\nmovements by a coupled electrometer with single-shot precision, or directly\nsense a spin-dependent quantum capacitance. These results bear significance for\nfast, high-fidelity single-shot readout of large arrays of foundrycompatible Si\nMOS spin qubits."
    },
    {
        "anchor": "Improved Efficiency of Photoconductive THz Emitters by Increasing the\n  Effective Contact Length of Electrodes: We study the effect of a surface modification at the interface between\nmetallic electrodes and semiconducting substrate in Semi-Insulating GaAs\n(SI-GaAs) based photoconductive emitters (PCE) on the emission of Tera-Hertz\n(THz) radiation. We partially etch out 500 nm thick layer of SI-GaAs in grating\nlike pattern with various periods before the contact deposition. By depositing\nthe electrodes on the patterned surface, the electrodes follow the contour of\nthe grating period. This increases the effective contact length of the\nelectrodes per unit area of the active regions on the PCE. The maxima of the\nelectric field amplitude of the THz pulses emitted from the patterned surface\nare enhanced by up to more than a factor 2 as compared to an un-patterned\nsurface. We attribute this increase to the increase of the effective contact\nlength of the electrode due to surface patterning.",
        "positive": "Evanescent incompressible strips as origin of the observed Hall\n  resistance overshoot: In this work we provide a systematic explanation to the unusual non-monotonic\nbehavior of the Hall resistance observed at two-dimensional electron systems.\nWe use a semi-analytical model based on the interaction theory of the integer\nquantized Hall effect to investigate the existence of the anomalous, \\emph{i.e}\novershoot, Hall resistance $R_{H}$. The observation of the overshoot resistance\nat low magnetic field edge of the plateaus is elucidated by means of\noverlapping evanescent incompressible strips, formed due to strong magnetic\nfields and interactions. Utilizing a self-consistent numerical scheme we also\nshow that, if the magnetic field is decreased the $R_{H}$ decreases to its\nexpected value. The effects of the sample width, temperature, disorder strength\nand magnetic field on the overshoot peaks are investigated in detail. Based on\nour findings, we predict a controllable procedure to manipulate the maxima of\nthe peaks, which can be tested experimentally. Our model does not depend on\nspecific and intrinsic properties of the material, provided that a single\nparticle gap exists."
    },
    {
        "anchor": "Multiscaling, Ergodicity and Localization in Quasiperiodic Chains: We report results of numerical simulations of wave-packet dynamics in a class\nof chains consisting of two types of weakly coupled clusters arranged in a\nquasiperiodic sequence. Properties of eigenstates are investigated using\nperturbation theory of degenerate levels in the coupling strength v and by\nnumerical diagonalization. Results show that wave packets anomalously diffuse\nvia a two-step process of rapid and slow expansions, which persist for any v>0.\nAn elementary analysis of the degenerate perturbation expansion reveals that\nnon-localized states may appear only in a sufficiently high order of\nperturbation theory, which is simply related to the combinatorial properties of\nthe sequences. Numerical diagonalization furthermore shows that eigenstates\nergodically spread across the entire chain for v>0, while in the limit as v->0\nergodicity is broken and eigenstates spread only across clusters of the same\ntype, in contradistinction with trivial localization at v=0. An investigation\nof the effects of a single-site perturbation on wave-packet dynamics shows\nthat, by changing the position or strength of such an impurity, it is possible\nto control the long-time wave-packet dynamics. By adding a single impurity it\nis possible to induce wave-packet localization on individual subchains as well\nas on the whole chain.",
        "positive": "Optical conductivity of disordered graphene beyond the Dirac cone\n  approximation: In this paper we systemically study the optical conductivity and density of\nstates of disorded graphene beyond the Dirac cone approximation. The optical\nconductivity of graphene is computed by using the Kubo formula, within the\nframework of a full \\pi-band tight-binding model. Different types of\nnon-correlated and correlated disorders are considered, such as random or\nGaussian potentials, random or Gaussian nearest-neighbor hopping parameters,\nrandomly distributed vacancies or their clusters, and random adsorbed hydrogen\natoms or their clusters. For a large enough concentration of resonant\nimpurities, a new peak in the optical conductivity is found, associated to\ntransitions between the midgap states and the Van Hove singularities of the\nmain \\pi-band. We further discuss the effect of doping on the spectrum, and\nfind that small amounts of resonant impurities are enough to obtain a\nbackground contribution to the conductivity in the infra-red part of the\nspectrum, in agreement with recent experiments."
    },
    {
        "anchor": "Modification of electronic, magnetic structure and topological phase of\n  bismuthene by point defects: This paper reveals how electronic, magnetic structure and topological phase\nof 2D, single-layer structures of bismuth are modified by point defects. We\nfirst showed that free standing, single-layer, hexagonal structure of bismuth,\nnamed as h-bismuthene exhibits non-trivial band topology. We then investigated\ninteractions between single foreign adatoms and bismuthene structures, which\ncomprise stability, bonding, electronic and magnetic structures. Localized\nstates in diverse location of the band gap and resonant states in band continua\nof bismuthene are induced upon the adsorption of different adatoms, which\nmodify electronic and magnetic properties. Specific adatoms result in\nreconstruction around the adsorption site. Single and divacancies can form\nreadily in bismuthene structures and remain stable at high temperatures.\nThrough rebondings Stone-Whales type defects are constructed by divacancies,\nwhich transform into a large hole at high temperature. Like adsorbed adatoms,\nvacancies induce also localized gap states, which can be eliminated through\nrebondings in divacancies. We also showed that not only optical and magnetic\nproperties, but also topological features of pristine h-bismuthene can be\nmodified by point defects. Modification of topological features depends on the\nenergies of localized states and also on the strength of coupling between point\ndefects.",
        "positive": "Insulating nanomagnets driven by spin torque: Magnetic insulators, such as yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$), are\nideal materials for ultra-low power spintronics applications due to their low\nenergy dissipation and efficient spin current generation and transmission.\nRecently, it has been realized that spin dynamics can be driven very\neffectively in micrometer-sized Y$_3$Fe$_5$O$_{12}$/Pt heterostructures by\nspin-Hall effects. We demonstrate here the excitation and detection of spin\ndynamics in Y$_3$Fe$_5$O$_{12}$/Pt nanowires by spin-torque ferromagnetic\nresonance. The nanowires defined via electron-beam lithography are fabricated\nby conventional room temperature sputtering deposition on Gd$_3$Ga$_5$O$_{12 }$\nsubstrates and lift-off. We observe field-like and anti-damping-like torques\nacting on the magnetization precession, which are due to simultaneous\nexcitation by Oersted fields and spin-Hall torques. The Y$_3$Fe$_5$O$_{12}$/Pt\nnanowires are thoroughly examined over a wide frequency and power range. We\nobserve a large change in the resonance field at high microwave powers, which\nis attributed to a decreasing effective magnetization due to microwave\nabsorption. These heating effects are much more pronounced in the investigated\nnanostructures than in comparable micron-sized samples. By comparing different\nnanowire widths, the importance of geometrical confinements for magnetization\ndynamics becomes evident: quantized spin-wave modes across the width of the\nwires are observed in the spectra. Our results are the first stepping stones\ntoward the realization of integrated magnonic logic devices based on\ninsulators, where nanomagnets play an essential role."
    },
    {
        "anchor": "Excitons dressed by a sea of excitons: We here consider an exciton $i$ embedded in a sea of $N$ identical excitons\n0. If the excitons are bosonized, a bosonic enhancement factor, proportional to\n$N$, is found for $i=0$. If the exciton composite nature is kept, this\nenhancement not only exists for $i=0$, but also for any exciton having a center\nof mass momentum equal to the sea exciton momentum. This physically comes from\nthe fact that an exciton with such a momentum can be transformed into a sea\nexciton by ``Pauli scattering'', \\emph{i}. \\emph{e}., carrier exchange with the\nsea, making this $i$ exciton not so much different from a 0 exciton. This\npossible scattering, directly linked to the composite nature of the excitons,\nis irretrievably lost when the excitons are bosonized.\n  This work in fact deals with the quite tricky scalar products of $N$-exciton\nstates. It actually constitutes a crucial piece of our new many-body theory for\ninteracting composite bosons, because all physical effects involving these\ncomposite bosons ultimately end by calculating such scalar products. The\n``Pauli diagrams'' we here introduce to represent them, allow to visualize\nmany-body effects linked to carrier exchange in an easy way. They are\nconceptually different from Feynman diagrams, because of the special feature of\nthe ``Pauli scatterings'': These scatterings, which originate from the\ndeparture from boson statistics, do not have their equivalent in Feynman\ndiagrams, the commutation rules for exact bosons (or fermions) being included\nin the first line of the usual many-body theories.",
        "positive": "Nonadiabatic dynamics near metal surfaces under Floquet engineering:\n  Floquet electronic friction vs. Floquet surface hopping: In the previous study (arXiv:2303.00479), we have derived a Floquet classical\nmaster equation (FCME) to treat nonadiabatic dynamics near metal surfaces under\nFloquet engineering. We have also proposed trajectory surface hopping algorithm\nto solve the FCME. In this study, we map the FCME into a Floquet Fokker-Planck\nequation in the limit of fast Floquet driving and fast electron motion as\ncompared to nuclear motion. The Fokker-Planck equation is then being solved\nusing Langevin dynamics with explicit friction and random force from the\nnonadiabatic effects of hybridized electron and Floquet states. We benchmark\nthe Floquet electronic friction (FEF) dynamics against Floquet quantum master\nequation (FQME) and Floquet surface hopping (FSH). We find that Floquet driving\nresults in violation of the second fluctuation-dissipation theorem, which\nfurther gives rise to heating effects."
    },
    {
        "anchor": "Control and ultrafast dynamics of a two-fluid polariton switch: We investigate the cross-interactions in a two-component polariton quantum\nfluid coherently driven by two independent pumping lasers tuned at different\nenergies and momenta. We show that both the hysteresis cycles and the ON/OFF\nthreshold of one polariton signal can be entirely controlled by a second\npolariton fluid. Furthermore, we study the ultrafast switching dynamics of a\ndriven polariton state, demonstrating the ability to control the polariton\npopulation with an external laser pulse, in less than a few picoseconds.",
        "positive": "Spin and tunneling dynamics in an asymmetrical double quantum dot with\n  spin - orbit coupling: In this article we study the spin and tunneling dynamics as a function of\nmagnetic field in a one-dimensional GaAs double quantum dot with both the\nDresselhaus and Rashba spin-orbit coupling. In particular we consider different\nspatial widths for the spin-up and spin-down electronic states. We find that\nthe spin dynamics is a superposition of slow as well as fast Rabi oscillations.\nIt is found that the Rashba interaction strength as well as the external\nmagnetic field strongly modifies the slow Rabi oscillations which is\nparticularly useful for single qubit manipulation for possible quantum computer\napplications."
    },
    {
        "anchor": "Topological Flat Bands in Graphene Super-moir\u00e9 Lattices: Moir\\'e-pattern based potential engineering has become an important way to\nexplore exotic physics in a variety of two-dimensional condensed matter\nsystems. While these potentials have induced correlated phenomena in almost all\ncommonly studied 2D materials, monolayer graphene has remained an exception. We\ndemonstrate theoretically that a single layer of graphene, when placed between\ntwo bulk boron nitride crystal substrates with the appropriate twist angles can\nsupport a robust topological ultra-flat band emerging from the second hole\nband. This is one of the simplest platforms to design and exploit topological\nflat bands.",
        "positive": "Entanglement spectra of superconductivity ground states on the honeycomb\n  lattice: We analytically evaluate the entanglement spectra of the superconductivity\nstates in graphene, primarily focusing on the s-wave and chiral $\nd_{x^{2}-y^{2}}+id_{xy} $ superconductivity states. We demonstrate that the\ntopology of the entanglement Hamiltonian can differ from that of the subsystem\nHamiltonian. In particular, the topological properties of the entanglement\nHamiltonian of the chiral $ d_{x^{2}-y^{2}}+id_{xy} $ superconductivity state\nobtained by tracing out one spin direction clearly differ from those of the\ntime-reversal invariant Hamiltonian of noninteracting fermions on the honeycomb\nlattice."
    },
    {
        "anchor": "Electro-optical properties of phosphorene quantum dots: We study electronic and optical properties of single layer phosphorene\nquantum dots with various shapes, sizes, and edge types (including disordered\nedges) subjected to an external electric field normal to the structure plane.\nCompared to graphene quantum dots, in phosphorene clusters of similar shape and\nsize there is a set of edge states with energies dispersed at around the Fermi\nlevel. These states make the majority of phosphorene quantum dots metallic and\nenrich the phosphorene absorption gap with low-energy absorption peaks tunable\nby the electric field. The presence of the edge states dispersed at around the\nFermi level is a characteristic feature that is independent of the edge\nmorphology and roughness.",
        "positive": "Epitaxial graphene on SiC: 2D sheets, selective growth and nanoribbons: Epitaxial graphene grown on SiC by the confinement controlled sublimation\nmethod is reviewed, with an emphasis on multilayer and monolayer epitaxial\ngraphene on the carbon face of 4H-SiC and on directed and selectively grown\nstructures under growth-arresting or growth-enhancing masks. Recent\ndevelopments in the growth of templated graphene nanostructures are also\npresented, as exemplified by tens of micron long very well confined and\nisolated 20-40nm wide graphene ribbons. Scheme for large scale integration of\nribbon arrays with Si wafer is also presented."
    },
    {
        "anchor": "Photon propagation in a one-dimensional optomechanical lattice: We consider a one-dimensional optomechanical lattice where each site is\nstrongly driven by a control laser to enhance the basic optomechanical\ninteraction. We then study the propagation of photons injected by an additional\nprobe laser beam; this is the lattice-generalization of the well-known\noptomechanically-induced transparency (OMIT) effect in a single optomechanical\ncavity. We find an interesting interplay between OMIT-type physics and\ngeometric, Fabry-Perot type resonances. In particular, phonon-like polaritons\ncan give rise to high-amplitude transmission resonances which are much narrower\nthan the scale set by internal photon losses. We also find that the local\nphoton density of states in the lattice exhibits OMIT-style interference\nfeatures. It is thus far richer than would be expected by just looking at the\nband structure of the dissipation-free coherent system.",
        "positive": "Current Rectification and Seebeck Coefficient of Serially Coupled Double\n  Quantum Dots: The transport properties of serially coupled quantum dots (SCQDs) embedded in\na matrix connected to metallic electrodes are theoretically studied in the\nlinear and nonlinear regimes. The current rectification and negative\ndifferential conductance of SCQDs under the Pauli spin blockade condition are\nattributed to the combination of bias-direction dependent probability weight\nand off-resonant energy levels yielded by the applied bias across the\njunctions. We observe the spin-polarization current rectification under the\nZeeman effect. The maximum spin-polarization current occurs in the forward bias\nregime. Such behavior is different from the charge current rectification.\nFinally, the Seebeck coefficient ($S$)of SCQDs is calculated and analyzed in\nthe cases without and with electron phonon interactions. The application of\nSCQDs as a temperature detector is discussed on the basis of the nonlinear\nbehavior of $S$ with respect to temperature difference across the junction."
    },
    {
        "anchor": "Theory of Berry Singularity Markers: Diagnosing Topological Phase\n  Transitions via Lock-In Tomography: This work brings forward an alternative experimental approach to infer the\ntopological character of phase transitions in insulators. This method relies on\nsubjecting the target system to a set of external fields, each of which\nconsists of two parts, i.e., a weak spatiotemporally slowly-varying component\non top of a constant offset. The fields are chosen in such a way, so that they\nrespectively induce slow variations in the wave vector describing the bulk band\nstructure, as well as a parameter which allows tuning the bulk gap. Such a\nprocess maps the Berry singularities of the base space to a synthetic space\nspanned by the parameters related to the external fields. By measuring the\nresponse of the system to the weak part of the perturbations, when these are\nadditionally chosen to form spacetime textures, one can construct a quantity\nthat is here-termed Berry singularity marker (BSM). The BSM enables the Berry\nsingularity detection as it becomes nonzero only in the close vicinity of a\nBerry singularity and is equal to its charge. The calculation of the BSM\nrequires the measurement of the susceptibility tensor for the applied external\nfields. Near the Berry singularities, the BSM is dominated by a universal\nvalue, which is determined by the quantum metric tensor of the system. While in\nthis work I restrict to 1D AIII insulators, the proposed approach is general.\nNotably, a key feature of the present method is that it can be implemented in a\nlock-in fashion, that is, one can \"filter out\" from the BSM any possible\ncontribution from disorder by performing more measurements. Hence, the present\nconstruction paves the way for a disorder resilient diagnosis of topological\nphase transitions, that appears particularly relevant for disordered\ntopological insulator and hybrid Majorana platforms, while it can be readily\nimplemented using topo-electric circuits.",
        "positive": "The impact of microcavity wire width on polariton soliton existence and\n  multistability: We have developed a model of the nonlinear polariton dynamics in realistic 3D\nnon-planar microcavity wires in the driven-dissipative regime. We find that the\ntypical microcavity optical bistability evolves into multistability upon\nvariation of the model parameters. The origin of the multistability is\ndiscussed in detail. We apply linear perturbation analysis to modulational\ninstabilities, and identify conditions for localisation of composite multi-mode\npolariton solitons in the triggered parametric oscillator regime. Further, we\ndemonstrate stable polariton soliton propagation in tilted and tapered\nwaveguides, and determine maximum tilt angles for which solitons still exist.\nAdditionally, we study soliton amplitude and velocity dependence on the wire\nwidth, with a view to engineering quantum photonic devices."
    },
    {
        "anchor": "Two-dimensional electron gas tilt-induced Landau level crossings: This work elucidates the novel behavior found in a two-dimensional electron\ngas (2DEG) under a tilted magnetic field in which the field's angle becomes the\ndominant factor in tuning the spin-splitting rather than the strength of the\nspin-orbit interaction. The 2DEG eigenvalues are derived with Rashba and Zeeman\ninteractions for various tilt angles and they show crossing-free levels except\nat very high tilt. Moreover, concomitant with the crossings is the appearance\nof beats in the 2DEG density of states. The crossings from different levels\noccur consecutively at around 87^{\\circ}. Similar new observations in\nShubnikov-de Haas experimental measurements by Hatke et al. [1] attributed such\nphenomena to an in-plane-magnetic-field-induced increase in the effective mass.\nWe show here that this behavior is inherent to a 2DEG where spin-orbit\ninteraction and the in-plane magnetic field contribution are taken into\naccount.",
        "positive": "Controlling electronic and adiabatic isolation of quantum dots from the\n  substrate: An ionization-energy theoretic study: Recent controversy on the quantum dots dephasing mechanisms (between pure and\ninelastic) is re-examined by isolating the quantum dots from their substrate by\nusing the appropriate limits of the ionization energy theory and the quantum\nadiabatic theorem. When the phonons in the quantum dots are isolated\nadiabatically from the phonons in the substrate, the elastic or pure dephasing\nbecomes the dominant mechanism. On the other hand, for the case where the\nphonons from the substrate are non-adiabatically coupled to the quantum dots,\nthe inelastic dephasing process takes over. This switch-over is due to\ndifferent elemental composition in quantum dots as compared to its substrate.\nWe also provide unambiguous analyses as to understand why GaAs/AlGaAs quantum\ndots may only have pure dephasing while InAs/GaAs quantum dots give rise to the\ninelastic dephasing as the dominant mechanism. Our study accentuates the\nimportance of the elemental composition (of both quantum dots and substrate) in\nevaluating the dephasing mechanisms of quantum dots."
    },
    {
        "anchor": "Electrical control of a confined electron spin in a silicene quantum dot: We study spin control for an electron confined in a flake of silicene. We\nfind that the lowest-energy conduction-band levels are split by the diagonal\nintrinsic spin-orbit coupling into Kramers doublets with a definite projection\nof the spin on the orbital magnetic moment. We study the spin control by AC\nelectric fields using the non-diagonal Rashba component of the spin-orbit\ninteractions with the time-dependent atomistic tight-binding approach. The\nRashba interactions in AC electric fields produce Rabi spin-flips times of the\norder of a nanosecond. These times can be reduced to tens of picoseconds\nprovided that the vertical electric field is tuned to an avoided crossing open\nby the Rashba spin-orbit interaction. We demonstrate that the speedup of the\nspin transitions is possible due to the intervalley coupling induced by the\narmchair edge of the flake. The study is confronted with the results for\ncircular quantum dots decoupled from the edge with well defined angular\nmomentum and valley index.",
        "positive": "Survival of $\u03a6_{0}/2$ periodicity in presence of incoherence in\n  asymmetric Aharonov-Bohm rings: Magneto conductance oscillations periodic in flux with periodicity $\\Phi_{0}$\nand $\\Phi_{0}/2$ are seen in asymmetric Aharonov-Bohm rings as a function of\ndensity of electrons or Fermi wave vector. Dephasing of these oscillations is\nincorporated using a simple approach of wave attenuation. In this work we study\nhow the excitation of the $\\Phi_{0}/2$ oscillations and the accompanying phase\nchange of $\\pi$ are affected by dephasing. Our results show that the\n$\\Phi_{0}/2$ oscillations survive incoherence, i.e., dephasing, albeit with\nreduced visibility while incoherence is also unable to obliterate the phase\nchange of $\\pi$."
    },
    {
        "anchor": "Controllable spin transport in ferromagnetic graphene junctions: We study spin transport in normal/ferromagnetic/normal graphene junctions\nwhere a gate electrode is attached to the ferromagnetic graphene. We find that\ndue to the exchange field of the ferromagnetic graphene, spin current through\nthe junctions has an oscillatory behavior with respect to the chemical\npotential in the ferromagnetic graphene, which can be tuned by the gate\nvoltage. Especially, we obtain a controllable spin current reversal by the gate\nvoltage. Our prediction of high controllability of spin transport in\nferromagnetic graphene junction may contribute to the development of the\nspintronics.",
        "positive": "Magnetic field tuning of exciton polaritons in a semiconductor\n  microcavity: We detail the influence of a magnetic field on exciton-polaritons inside a\nsemiconductor microcavity. Magnetic field can be used as a tuning parameter for\nexciton and photon resonances. We discuss the change of the exciton energy, the\noscillator strength and redistribution of the polariton density along the\ndispersion curves due to the magnetically-induced detuning. We have observed\nthat field-induced shrinkage of the exciton wave function has a direct\ninfluence not only on the exciton oscillator strength, which is observed to\nincrease with the magnetic field, but also on the polariton linewidth. We\ndiscuss the effect of the Zeeman splitting on polaritons which magnitude\nchanges with the exciton Hopfield coefficient and can be modelled by\nindependent coupling of the two spin components of excitons with cavity\nphotons."
    },
    {
        "anchor": "Configuration space method for calculating binding energies of exciton\n  complexes in quasi-1D/2D semiconductors: A configuration space method is developed for binding energy calculations of\nthe lowest energy exciton complexes (trion, biexciton) in spatially confined\nquasi-1D semiconductor nanostructures such as nanowires and nanotubes. Quite\ngenerally, trions are shown to have greater binding energy in strongly confined\nstructures with small reduced electron-hole masses. Biexcitons have greater\nbinding energy in less confined structures with large reduced electron-hole\nmasses. This results in a universal crossover behavior, whereby trions become\nless stable than biexcitons as the transverse size of the quasi-1D\nnanostructure increases. The method is also capable of evaluating binding\nenergies for electron-hole complexes in quasi-2D semiconductors such as coupled\nquantum wells and bilayer van der Walls bound heterostructures with advanced\noptoelectronic properties.",
        "positive": "Spectral scrambling in Coulomb-blockade quantum dots: We study the fluctuations of an energy level as a function of the number of\nelectrons $m$ added to a Coulomb-blockade quantum dot. A microscopic\ncalculation in the limit of Koopmans' theorem predicts that the standard\ndeviation of these fluctuations behaves as $\\sqrt{m}$ in the absence of surface\ncharge but is linear in $m$ when the effect of a surface charge in a finite\ngeometry is included. The microscopic results are compared to a parametric\nrandom-matrix approach. We estimate the number of electrons it takes to\nscramble the spectrum completely in terms of the interaction strength, the\ndimensionless Thouless conductance, and the symmetry class."
    },
    {
        "anchor": "Cooling of nanomechanical resonator by thermally activated\n  single-electron transport: We show that the vibrations of a nanomechanical resonator can be cooled to\nnear its quantum ground state by tunnelling injection of electrons from an STM\ntip. The interplay between two mechanisms for coupling the electronic and\nmechanical degrees of freedom results in a bias-voltage dependent difference\nbetween the probability amplitudes for vibron emission and absorption during\ntunneling. For a bias voltage just below the Coulomb blockade threshold we find\nthat absorption dominates, which leads to cooling corresponding to an average\nvibron population of the fundamental bending mode of 0.2.",
        "positive": "Terahertz continuum generation in the LCS lattice: Rabi oscillations in two-level Dirac systems have been shown to alter the\nfrequency content of the system's nonlinear response. In particular, when\nconsidering Rabi oscillations in a quantum model beyond the semiclassical\nBoltzmann theory, even harmonics may be generated despite the centrosymmetric\nnature of these systems. This effect magnifies with increasing excitation\nintensity. In this work, we extend the Rabi theory to a three-level Dirac\nsystem arising from a line-centered-square optical lattice. In this case, the\nDirac cones are bisected at the Dirac point by a flat band that persists\nthroughout the Brillioun zone. Due to the presence of this flat band, we expect\na significant enhancement of the coupling between Dirac states, resulting in a\nlarge increase of the Rabi effects and the associated nonlinearities, leading\nto continuum generation of terahertz radiation."
    },
    {
        "anchor": "Coherence and Phase in an Electronic Mach-Zehnder Interferometer: An\n  Unexpected Behavior of Interfering Electrons: We report the observation of an unpredicted behavior of interfering 2D\nelectrons in the integer quantum Hall effect (IQHE) regime via a utilization of\nan electronic analog of the well-known Mach-Zehnder interferometer (MZI). The\nbeauty of this experiment lies in the simplicity of two path interference.\nElectrons that travel the two paths via edge channels, feel only the edge\npotential and the strong magnetic field; both typical in the IQHE regime. Yet,\nthe interference of these electrons via the Aharonov-Bohm (AB) effect, behaves\nsurprisingly in a most uncommon way.\n  We found, at filling factors 1 and 2, high visibility interference\noscillations, which were strongly modulated by a lobe-type structure as we\nincreased the electron injection voltage. The visibility went through a few\nmaxima and zeros in between, with the phase of the AB oscillations staying\nconstant throughout each lobe and slipping abruptly by at each zero. The lobe\npattern and the 'stick-slip' behavior of the phase were insensitive to details\nof the interferometer structure; but highly sensitive to magnetic field. The\nobserved periodicity defines a 'new energy scale' with an unclear origin. The\nphase rigidity, on the other hand, is surprising since Onsager relations are\nnot relevant here.",
        "positive": "Mobility exceeding 100,000 cm$^2$/Vs in modulation-doped shallow InAs\n  quantum wells coupled to epitaxial aluminum: The two-dimensional electron gas residing in shallow InAs quantum wells\ncoupled to epitaxial aluminum is a widely utilized platform for exploration of\ntopological superconductivity. Strong spin-orbit coupling, large effective\n$g$-factor, and control over proximity-induced superconductivity are important\nattributes. Disorder in shallow semiconductor structures plays a crucial role\nfor the stability of putative topological phases in hybrid structures. We\nreport on the transport properties of 2DEGs residing 10nm below the surface in\nshallow InAs quantum wells in which mobility may exceed 100,000 cm$^2$/Vs at\n2DEG density n$_{2DEG}$$\\leq$1$\\times$10$^{12}$cm$^{-2}$ at low temperature."
    },
    {
        "anchor": "Pseudo chiral anomaly in zigzag graphene ribbons: As the three-dimensional analogs of graphene, Weyl semimetals display\nsignatures of chiral anomaly which arises from charge pumping between the\nlowest chiral Landau levels of the Weyl nodes in the presence of parallel\nelectric and magnetic fields. In this work, we study the pseudo chiral anomaly\nand its transport signatures in graphene ribbon with zigzag edges. Here\n\"pseudo\" refers to the case where the inverse of width of zigzag graphene\nribbon plays the same role as magnetic field in three-dimensional Weyl\nsemimetals. The valley chiral bands in zigzag graphene ribbons can be\nintroduced by edge potentials, giving rise to the nonconservation of chiral\ncurrent, i.e., pseudo chiral anomaly, in the presence of a longitudinal\nelectric field. Further numerical results reveal that pseudo\nmagnetoconductivity of zigzag graphene ribbons is positive and has a nearly\nquadratic dependence on the pseudofield, which is regarded as the transport\nsignature of pseudo chiral anomaly.",
        "positive": "Electronic and transport properties of azobenzene monolayer junctions as\n  molecular switches: We investigate from first-principles the change in transport properties of a\ntwo-dimensional azobenzene monolayer sandwiched between two Au electrodes that\nundergoes molecular switching. We focus on transport differences between a\nchemisorbed and physisorbed top monolayer-electrode contact. The conductance of\nthe monolayer junction with a chemisorbed top contact is higher in trans\nconfiguration, in agreement with the previous theoretical predictions of\none-dimensional single molecule junctions. However, with a physisorbed top\ncontact, the \"ON\" state with larger conductance is associated with the cis\nconfiguration due to a reduced effective tunneling pathway by switching from\ntrans to cis, which successfully explains recently experimental measurements of\nazobenzene monolayer junctions. A simple model is developed to explain electron\ntransmission across subsystems in the molecular junction. We also discuss the\neffects of monolayer packing density, molecule tilt angle, and contact geometry\non the calculated transmission functions. In particular, we find that a\ntip-like contact with chemisorption significantly affects the electric current\nthrough the cis monolayer, leading to highly asymmetric current-voltage\ncharacteristics as well as large negative differential resistance behavior."
    },
    {
        "anchor": "Superconductivity in a single C60 transistor: Single molecule transistors (SMTs) are currently attracting enormous\nattention as possible quantum information processing devices. An intrinsic\nlimitation to the prospects of these however is associated to the presence of a\nsmall number of quantized conductance channels, each channel having a high\naccess resistance of at best $R_{K}/2=h/2e^{2}$=12.9 k$\\Omega$. When the\ncontacting leads become superconducting, these correlations can extend\nthroughout the whole system by the proximity effect. This not only lifts the\nresistive limitation of normal state contacts, but further paves a new way to\nprobe electron transport through a single molecule. In this work, we\ndemonstrate the realization of superconducting SMTs involving a single C60\nfullerene molecule. The last few years have seen gate-controlled Josephson\nsupercurrents induced in the family of low dimensional carbon structures such\nas flakes of two-dimensional graphene and portions of one-dimensional carbon\nnanotubes. The present study involving a full zero-dimensionnal fullerene\ncompletes the picture.",
        "positive": "An Accurate Current Model for III-V Field Effect Transistors Using a\n  Novel Concept of Effective Transmission Coefficient: In this work, we investigate the transport phenomena in compound\nsemiconductor material based buried channel Quantum Well MOSFET with a view to\ndeveloping a simple and effective model for the device current. Device\nsimulation has been performed in quantum ballistic regime using non-equilibrium\nGreens function (NEGF) formalism. The simulated current voltage characteristics\nusing a novel concept of effective transmission coefficient has been found to\ndefine the reported experimental data with high accuracy. The proposed model\nhas also been effective to capture the transport characteristics reported for\nother compound semiconductor material based field effect transistors. The\nconcept of the proposed effective transmission coefficient and hence the model\nlends itself to be a simple and powerful device analysis tool which can be\nextensively used to predict the performance of a wide variety of compound\nsemiconductor devices in the pre fabrication stage. It has also demonstrated\nconsistency with device characteristics for doping concentration and channel\nlength scaling. Thus the model can help the device or process engineers to tune\nthe devices for the best possible performance."
    },
    {
        "anchor": "Transport theory and spin-transfer physics for frustrated magnets: We study the electron dynamics in magnetic conductors with frustrated\ninteractions dominated by isotropic exchange. We present a transport theory for\nitinerant carriers built upon the (single-band) doped Hubbard model and the\nslave-boson formalism, which incorporates the spin-exchange with the\nmagnetically frustrated background into the representation of electron\noperators in a clear and controllable way. We also formulate hydrodynamic\nequations for the itinerant charge and spin degrees of freedom, whose currents\ncontain new contributions that depend on the spatiotemporal variations of the\norder parameter of the frustrated magnet, which are described by Yang-Mills\nfields. Furthermore, we elucidate the transfer of angular momentum from the\nitinerant charge fluid to the magnet (i.e., the spin-transfer torque) via\nreciprocity arguments. A detailed microscopic derivation of our effective\ntheory is also provided for one of the simplest models of frustrated magnetism,\nnamely the Heisenberg antiferromagnet on a triangular lattice. Our findings\npoint towards the possibility of previously unanticipated Hall physics in these\nfrustrated platforms.",
        "positive": "Coupling of evanescent waves into propagation channels within\n  two-dimensional random waveguides: The transformation from evanescent waves to propagation waves is the key\nmechanism for the realization of some super-resolution imaging methods. By\nusing the recursive Green function and scattering-matrix theory, we\ninvestigated in details on the transport of evanescent waves through a random\nmedium and analyzed quantitatively the coupling of evanescent channels to\npropagation channels. By numerical calculations, we found that the transmission\nfor the incident evanescent channel is determined by both the eigenvalues of\nthe scattering matrix and the coupling strength to the corresponding\npropagation channels in random medium, and the disorder strength of the random\nmedium influences both of them."
    },
    {
        "anchor": "Evidence of decoupling of surface and bulk states in Dirac semimetal\n  $Cd_{3}As_{2}$: Dirac semimetals have attracted a great deal of current interest due to their\npotential applications in topological quantum computing, low-energy electronic\napplications, and single photon detection in the microwave frequency range.\nHerein are results from analyzing the low magnetic (B) field\nweak-antilocalization behaviors in a Dirac semimetal $Cd_{3}As_{2}$ thin flake\ndevice. At high temperatures, the phase coherence length $l_{\\phi}$ first\nincreases with decreasing temperature (T) and follows a power law dependence of\n$l_{\\phi}\\propto$ T$^{-0.4}$. Below ~ 3K, $l_{\\phi}$ tends to saturate to a\nvalue of ~ 180 nm. Another fitting parameter $\\alpha$, which is associated with\nindependence transport channels, displays a logarithmic temperature dependence\nfor T > 3K, but also tends to saturate below ~ 3K. The saturation value, ~\n1.45, is very close to 1.5, indicating three independent electron transport\nchannels, which we interpret as due to decoupling of both the top and bottom\nsurfaces as well as the bulk. This result, to our knowledge, provides first\nevidence that the surfaces and bulk states can become decoupled in electronic\ntransport in Dirac semimetal $Cd_{3}As_{2}$.",
        "positive": "Semiclassical Theory for Decay and Fragmentation Processes in Chaotic\n  Quantum Systems: We consider quantum decay and photofragmentation processes in open chaotic\nsystems in the semiclassical limit. We devise a semiclassical approach which\nallows us to consistently calculate quantum corrections to the classical decay\nto high order in an expansion in the inverse Heisenberg time. We present\nresults for systems with and without time reversal symmetry and also for the\nsymplectic case, as well as extending recent results to non-localized initial\nstates. We further analyze related photodissociation and photoionization\nphenomena and semiclassically compute cross-section correlations, including\ntheir Ehrenfest time dependence."
    },
    {
        "anchor": "Nonlinearity of Acoustic Effects and High-Frequency Electrical\n  Conductivity in GaAs/AlGaAs Heterostructures under Conditions of the Integer\n  Quantum Hall Effect: The absorption coefficient for surface acoustic wave $\\Gamma$ and variation\nin the wave velocity $\\Delta V/V$ were measured in GaAs/AlGaAs\nheterostructures; the above quantities are related to interaction of the wave\nwith two-dimensional electron gas and depend nonlinearly on the power of the\nwave. Measurements were performed under conditions of the integer quantum Hall\neffect (IQHE), in which case the two-dimensional electron gas was localized in\na random fluctuation potential of impurities. The dependences of the components\n$\\sigma_1(E)$ and $\\sigma_2(E)$ of high-frequency conductivity $\\sigma=\\sigma_1\n- i\\sigma_2$ on the electric field of the surface wave were determined. In the\nrange of the conductivity obeying the Arrhenius law ($\\sigma_1 \\gg \\sigma_2$),\nthe results obtained are interpreted in terms of the Shklovskii theory of\nnonlinear percolation-based conductivity, which makes it possible to estimate\nthe magnitude of the fluctuation potential of impurities. The dependences\n$\\sigma_1(E)$ and $\\sigma_2(E)$ in the range of high-frequency hopping\nelectrical conductivity, in which case ($\\sigma_1 \\ll \\sigma_2$) and the theory\nof nonlinearities has not been yet developed, are reported.",
        "positive": "Fast Long-Distance Control of Spin Qubits by Photon Assisted Cotunneling: We investigate theoretically the long-distance coupling and spin exchange in\nan array of quantum dot spin qubits in the presence of microwaves. We find that\nphoton assisted cotunneling is boosted at resonances between photon and\nenergies of virtually occupied excited states and show how to make it spin\nselective. We identify configurations that enable fast switching and spin echo\nsequences for efficient and non-local manipulation of spin qubits. We devise\nconfigurations in which the near-resonantly boosted cotunneling provides\nnon-local coupling which, up to certain limit, does not diminish with distance\nbetween the manipulated dots before it decays weakly with inverse distance."
    },
    {
        "anchor": "Dynamical signature of a domain phase transition in a\n  perpendicularly-magnetized ultrathin film: Domain phases in ultrathin Fe/Ni/W(110) films with perpendicular anisotropy\nhave been studied using the ac magnetic susceptibility. Dynamics on time scales\nof minutes to hours were probed by quenching the system from high temperature\nto the stripe phase region, and varying the constant rate of temperature\nincrease as the susceptibility traces were measured. The entire susceptibility\npeak is observed to relax slowly along the temperature axis, with the peak\ntemperature increasing as the rate of heating is decreased. This is precisely\nopposite to what would happen if this slow relaxation was driven by changes in\nthe domain density within the stripe phase. The data are instead consistent\nwith a simple model for the removal of a significant density of pattern defects\nand curvature trapped in the quench from high temperature. A quantitative\nanalysis confirms that the relaxation dynamics are consistent with the\nmesoscopic rearrangement of domains required to remove pattern defects, and\nthat the experiment constitutes a \"dynamical\" observation of the phase\ntransition from a high temperature, positionally disordered phase to the low\ntemperature, ordered stripe phase.",
        "positive": "Interface effects on acceptor qubits in silicon and germanium: Dopant-based quantum computing implementations often require the dopants to\nbe situated close to an interface to facilitate qubit manipulation with local\ngates. Interfaces not only modify the energies of the bound states but also\naffect their symmetry. Making use of the successful effective mass theory we\nstudy the energy spectra of acceptors in Si or Ge taking into account the\nquantum confinement, the dielectric mismatch and the central cell effects. The\npresence of an interface puts constraints to the allowed symmetries and lead to\nthe splitting of the ground state in two Kramers doublets [J. Mol et al, App.\nPhys. Lett. 106, 203110 (2015)]. Inversion symmetry breaking also implies\nparity mixing which affects the allowed optical transitions. Consequences for\nacceptor qubits are discussed."
    },
    {
        "anchor": "Quantum Theory of Spin-Transfer and Spin-Pumping in Collinear\n  Antiferromagnets and Ferrimagnets: Antiferromagnets are promising candidates as active components in spintronic\napplications. They share features with ferrimagnets in that opposing spin\norientations exist in two or more sublattices. Spin transfer torque and spin\npumping are essential ingredients in antiferromagnetic and ferrimagnet\nspintronics. This paper develops an out-of-equilibrium quantum theory of the\nspin dynamics of collinear magnets containing many spins coupled to normal\nmetal reservoirs. At equilibrium, the spins are parallel or antiparallel to the\neasy axis. The theory, therefore, covers collinear antiferromagnets and\nferrimagnets. We focus on the resulting semi-classical spin dynamics. The\ndissipation in the spin dynamics is enhanced due to spin-pumping. Spin\naccumulations in the normal metals induce deterministic spin-transfer torques\non the magnet. Additionally, each electron's discrete spin angular momentum\ncauses stochastic fluctuating torques on the antiferromagnet or ferrimagnet. We\nderive these fluctuating torques. The fluctuation-dissipation theorem holds at\nhigh temperatures, including the effects of spin-pumping. At low temperatures,\nwe derive shot noise contributions to the fluctuations.",
        "positive": "Measurement of cryoelectronics heating using a local quantum dot\n  thermometer in silicon: Silicon technology offers the enticing opportunity for monolithic integration\nof quantum and classical electronic circuits. However, the power consumption\nlevels of classical electronics may compromise the local chip temperature and\nhence the fidelity of qubit operations. Here, we utilize a quantum-dot-based\nthermometer embedded in an industry-standard silicon field-effect transistor\n(FET), to assess the local temperature increase produced by an active FET\nplaced in close proximity. We study the impact of both static and dynamic\noperation regimes. When the FET is operated statically, we find a power budget\nof 45 nW at 100 nm separation whereas at 216 $\\mu$m the power budget raises to\n150 $\\mu$W. When operated dynamically, we observe negligible temperature\nincrease for the switch frequencies tested up to 10 MHz. Our work describes a\nmethod to accurately map out the available power budget at a distance from a\nsolid-state quantum processor and indicate under which conditions\ncryoelectronics circuits may allow the operation of hybrid quantum-classical\nsystems."
    },
    {
        "anchor": "Correlations of conductance peaks and transmission phases in deformed\n  quantum dots: We investigate the Coulomb blockade resonances and the phase of the\ntransmission amplitude of a deformed ballistic quantum dot weakly coupled to\nleads. We show that preferred single--particle levels exist which stay close to\nthe Fermi energy for a wide range of values of the gate voltage. These states\ngive rise to sequences of Coulomb blockade resonances with correlated peak\nheights and transmission phases. The correlation of the peak heights becomes\nstronger with increasing temperature. The phase of the transmission amplitude\nshows lapses by $\\pi$ between the resonances. Implications for recent\nexperiments on ballistic quantum dots are discussed.",
        "positive": "Non-equilibrium Fluctuation Relations in a Quantum Coherent Conductor: We experimentally demonstrate the validity of non-equilibrium fluctuation\nrelations by using a quantum coherent conductor. In equilibrium the\nfluctuation-dissipation relation leads to the correlation between current and\ncurrent noise at the conductor, namely, Johnson-Nyqusit relation. When the\nconductor is voltage-biased so that the non-linear regime is entered, the\nfluctuation theorem has predicted similar non-equilibrium fluctuation\nrelations, which hold true even when the Onsager-Casmir relations are broken in\nmagnetic fields. Our experiments qualitatively validate the predictions as the\nfirst evidence of this theorem in the non-equilibrium quantum regime.\n  In the appendix, we give simple deduction of the higher order correlations\nbetween the current and the current noise based on the fluctuation theorem."
    },
    {
        "anchor": "Fingerprints of spatial charge transfer in Quantum Cascade Lasers: We show that mid infrared transmission spectroscopy of a quantum cascade\nlaser provides clear cut information on changes in charge location at different\nbias. Theoretical simulations of the evolution of the gain/absorption spectrum\nfor the $\\lambda \\sim$ 7.4 $\\mu$m InGaAs/AlInAs/InP quantum cascade laser have\nbeen compared with the experimental findings. Transfer of electrons between the\nground states in the active region and the states in the injector goes in hand\nwith a decrease of discrete intersubband absorption peaks and an increase of\nbroad high-energy absorption towards the continuum delocalised states above the\nbarriers.",
        "positive": "Topological phonon transport in an optomechanical system: Recent advances in cavity-optomechanics have now made it possible to use\nlight not just as a passive measuring device of mechanical motion, but also to\nmanipulate the motion of mechanical objects down to the level of individual\nquanta of vibrations (phonons). At the same time, microfabrication techniques\nhave enabled small-scale optomechanical circuits capable of on-chip\nmanipulation of mechanical and optical signals. Building on these developments,\ntheoretical proposals have shown that larger scale optomechanical arrays can be\nused to modify the propagation of phonons, realizing a form of topologically\nprotected phonon transport. Here, we report the observation of topological\nphonon transport within a multiscale optomechanical crystal structure\nconsisting of an array of over $800$ cavity-optomechanical elements. Using\nsensitive, spatially resolved optical read-out we detect thermal phonons in a\n$0.325-0.34$GHz band traveling along a topological edge channel, with\nsubstantial reduction in backscattering. This represents an important step from\nthe pioneering macroscopic mechanical systems work towards topological phononic\nsystems at the nanoscale, where hypersonic frequency ($\\gtrsim$GHz) acoustic\nwave circuits consisting of robust delay lines and non-reciprocal elements may\nbe implemented. Owing to the broadband character of the topological channels,\nthe control of the flow of heat-carrying phonons, albeit at cryogenic\ntemperatures, may also be envisioned."
    },
    {
        "anchor": "Robust single-parameter quantized charge pumping: This paper investigates a scheme for quantized charge pumping based on\nsingle-parameter modulation. The device was realized in an AlGaAs-GaAs gated\nnanowire. We find a remarkable robustness of the quantized regime against\nvariations in the driving signal, which increases with applied rf power. This\nfeature together with its simple configuration makes this device a potential\nmodule for a scalable source of quantized current.",
        "positive": "Relaxation Oscillations in the Formation of a Polariton Condensate: We report observation of oscillations in the dynamics of a microcavity\npolariton condensate formed under pulsed non resonant excitation. While\noscillations in a condensate have always been attributed to Josephson\nmechanisms due to a chemical potential unbalance, here we show that under some\nlocalisation conditions of the condensate, they may arise from relaxation\noscillations, a pervasive classical dynamics that repeatedly provokes the\nsudden decay of a reservoir, shutting off relaxation as the reservoir is\nreplenished. Using non-resonant excitation, it is thus possible to obtain\ncondensate injection pulses with a record frequency of 0:1 THz."
    },
    {
        "anchor": "Molecular wires acting as quantum heat ratchets: We explore heat transfer in molecular junctions between two leads in the\nabsence of a finite net thermal bias. The application of an unbiased,\ntime-periodic temperature modulation of the leads entails a dynamical breaking\nof reflection symmetry, such that a directed heat current may emerge (ratchet\neffect). In particular, we consider two cases of adiabatically slow driving,\nnamely (i) periodic temperature modulation of only one lead and (ii)\ntemperature modulation of both leads with an ac driving that contains a second\nharmonic, thus generating harmonic mixing. Both scenarios yield sizeable\ndirected heat currents which should be detectable with present techniques.\nAdding a static thermal bias, allows one to compute the heat current-thermal\nload characteristics which includes the ratchet effect of negative thermal bias\nwith positive-valued heat flow against the thermal bias, up to the thermal\nstop-load. The ratchet heat flow in turn generates also an electric current. An\napplied electric stop-voltage, yielding effective zero electric current flow,\nthen mimics a solely heat-ratchet-induced thermopower (``ratchet Seebeck\neffect''), although no net thermal bias is acting. Moreover, we find that the\nrelative phase between the two harmonics in scenario (ii) enables steering the\nnet heat current into a direction of choice.",
        "positive": "Ripplocation in graphite nanoplatelets during sonication assisted liquid\n  phase exfoliation: Defects induced by liquid-phase exfoliation of graphite using sonication were\nstudied. It was shown that localized impact by cavitation shock waves can\nproduce bulk ripplocations and various types of dislocations in graphite\nnanoplatelets. Formation of ripples is more pronounced in large aspect\n(length/width) ratio platelets or nanobelts. Quasi-periodical ripple systems\nwere observed in many nanobelts after sonication. Mechanism of formation of\nripples and dislocations during sonication was proposed. Surprisingly, fast\nhigh-temperature processing was found to anneal most of defects. This is\nconsistent with our observations that defects associated with ripplocations are\nstrongly localized and thus can be fast annealed."
    },
    {
        "anchor": "Electrical and thermoelectrical transport in Dirac fermions through a\n  quantum dot: We investigate the conductance and thermopower of massless Dirac fermions\nthrough a quantum dot using a pseudogap Anderson model in the non-crossing\napproximation. When the Fermi level is at the Dirac point, the conductance has\na cusp where the thermopower changes its sign. When the Fermi level is away\nfrom the Dirac point, the Kondo temperature illustrates a quantum impurity\ntransition between an asymmetric strong coupling Kondo state and a localized\nmoment state. The conductance shows a peak near this transition and reaches the\nunitary limit at low temperatures. The magnitude of the thermopower exceeds\n$k_B/e$, and the thermoelectric figure of merit exceeds unity.",
        "positive": "Chiral Pumping of Spin Waves: We report a theory for the coherent and incoherent chiral pumping of spin\nwaves into thin magnetic films through the dipolar coupling with a local\nmagnetic transducer, such as a nanowire. The ferromagnetic resonance of the\nnanowire is broadened by the injection of unidirectional spin waves that\ngenerate a non-equilibrium magnetization in only half of the film. A\ntemperature gradient between the local magnet and film leads to a\nunidirectional flow of incoherent magnons, i.e., a chiral spin Seebeck effect."
    },
    {
        "anchor": "Multibands Tunneling in AAA-Stacked Trilayer Graphene: We study the electronic transport through np and npn junctions for\nAAA-stacked trilayer graphene. Two kinds of gates are considered where the\nfirst is a single gate and the second is a double gate. After obtaining the\nsolutions for the energy spectrum, we use the transfer matrix method to\ndetermine the three transmission probabilities for each individual cone\n$\\tau=0, \\pm 1$. We show that the quasiparticles in AAA-stacked trilayer\ngraphene are not only chiral but also labeled by an additional cone index\n$\\tau$. The obtained bands are composed of three Dirac cones that depend on the\nchirality indexes. We show that there is perfect transmission for normal or\nnear normal incidence, which is a manifestation of the Klein tunneling effect.\nWe analyze also the corresponding total conductance, which is defined as the\nsum of the conductance channels in each individual cone. Our results are\nnumerically discussed and compared with those obtained for ABA- and ABC-stacked\ntrilayer graphene.",
        "positive": "Spin-squeezed Ground States in the Bilayer Quantum Hall Ferromagnet: A \"squeezed-vacuum\" state considered in quantum optics is shown to be\nrealized in the ground-state wavefunction for the bilayer quantum Hall system\nat the total Landau level filling of $\\nu=1/m$ (m: odd integer). This is\nderived in the boson approximation, where a particle-hole pair creation across\nthe symmetric-antisymmetric gap, $\\Delta_{SAS}$, is regarded as a boson. In\nterms of the pseudospin describing the layers, the state is a spin-squeezed\nstate, where the degree of squeezing is controlled by the layer separation and\n$\\Delta_{SAS}$. An exciton condensation, which amounts to a rotated\nspin-squeezed state, has a higher energy due to the degraded SU(2) symmetry for\n$\\Delta_{SAS} \\neq 0$."
    },
    {
        "anchor": "Conductance saturation in a series of highly transmitting molecular\n  junctions: Understanding the properties of electronic transport across metal-molecule\ninterfaces is of central importance for controlling a large variety of\nmolecular-based devices such as organic light emitting diodes, nanoscale\norganic spin-valves and single-molecule switches. One of the primary\nexperimental methods to reveal the mechanisms behind electronic transport\nthrough metal-molecule interfaces is the study of conductance as a function of\nmolecule length in molecular junctions. Previous studies focused on transport\ngoverned either by tunneling or hopping, both at low conductance. However, the\nupper limit of conductance across molecular junctions has not been explored,\ndespite the great potential for efficient information transfer, charge\ninjection and recombination processes. Here, we study the conductance\nproperties of highly transmitting metal-molecule-metal interfaces, using a\nseries of single-molecule junctions based on oligoacenes with increasing\nlength. We find that the conductance saturates at an upper limit where it is\nindependent of molecule length. Furthermore, we show that this upper limit can\nbe controlled by the character of the orbital hybridization at the\nmetal-molecule interface. Using two prototype systems, in which the molecules\nare contacted by either Ag or Pt electrodes, we reveal two different origins\nfor the saturation of conductance. In the case of Ag-based molecular junctions,\nthe conductance saturation is ascribed to a competition between energy level\nalignment and level broadening, while in the case of Pt-based junctions, the\nsaturation is attributed to a band-like transport. The results are explained by\nan intuitive model, backed by ab-initio transport calculations. Our findings\nshed light on the mechanisms that constrain the conductance at the high\ntransmission limit, providing guiding principles for the design of highly\nconductive metal-molecule interfaces.",
        "positive": "Electronic states and Landau levels in graphene stacks: We analyze, within a minimal model that allows analytical calculations, the\nelectronic structure and Landau levels of graphene multi-layers with different\nstacking orders. We find, among other results, that electrostatic effects can\ninduce a strongly divergent density of states in bi- and tri-layers,\nreminiscent of one-dimensional systems. The density of states at the surface of\nsemi-infinite stacks, on the other hand, may vanish at low energies, or show a\nband of surface states, depending on the stacking order."
    },
    {
        "anchor": "Room temperature ferromagnetism and anomalous Hall effect in\n  Si$_{1-x}$Mn$_x$ ($x\\approx 0.35$) alloys: A detailed study of the magnetic and transport properties of Si$_{1-x}$Mn$_x$\n($x\\approx 0.35$) films is presented. We observe the anomalous Hall effect\n(AHE) in these films up to room temperature. The results of the magnetic\nmeasurements and the AHE data are consistent and demonstrate the existence of\nlong-range ferromagnetic (FM) order in the systems under study. A correlation\nof the AHE and the magnetic properties of Si$_{1-x}$Mn$_x$ ($x\\approx 0.35$)\nfilms with their conductivity and substrate type is shown. A theoretical model\nbased on the idea of a two-phase magnetic material, in which molecular clusters\nwith localized magnetic moments are embedded in the matrix of a weak itinerant\nferromagnet, is discussed. The long-range ferromagnetic order at high\ntemperatures is mainly due to the Stoner enhancement of the exchange coupling\nbetween clusters through thermal spin fluctuations (paramagnons) in the matrix.\nTheoretical predictions and experimental data are in good qualitative\nagreement.",
        "positive": "Spin excitation spectra of integral and fractional quantum Hall systems: Results are presented of detailed numerical calculations for the spin\nexcitation spectra of a two-dimensional electron gas confined in a quantum well\nof finite width w, at magnetic fields corresponding to the fractional and\nintegral fillings of the lowest and of excited Landau levels. Spin waves and\nskyrmions are identified, and their mutual interactions are studied at filling\nfactors nu=1/3, 1, 3, and 5. The smallest skyrmions at nu=1/3 are equivalent to\ncomposite fermion charged excitons X_CF^(+/-). Bose condensates of nearly\nnoninteracting spin waves and Laughlin correlations between finite-size\nskyrmions are found at nu=1 and 1/3 and, for w larger than about two magnetic\nlengths, also at nu=3 and 5. A general criterion for the occurrence of\nskyrmions at odd integral fillings and at Laughlin fractional fillings of the\nlowest Landau level is given in terms of the interaction pseudopotentials. This\nexplains the dependence of skyrmion states on w observed in excited Landau\nlevels."
    },
    {
        "anchor": "Time-dependent Goos-H\u00e4nchen Shifts in Gapped Graphene: We study the Goos-H\\\"anchen (GH) shifts for transmitted Dirac fermions in\ngapped graphene through a single barrier structure having a time periodic\noscillating component. Our analysis shows that the GH shifts in transmission\nfor central band $l=0$ and two first sidebands $l=\\pm1$ change sign at the\nDirac points $E=V+l\\hbar\\omega$. In particular the GH shifts inbtransmission\nexhibit enhanced peaks at each bound state associated with the single barrier\nwhen the incident angle is less than the critical angle associated with total\nreflection. Klein tunneling, reflected by perfect transmission at normal\nincidence, is also preserved in the presence of an oscillating barrier.",
        "positive": "Tunneling current spectroscopy of a nanostructure junction involving\n  multiple energy levels: A multi-level Anderson model is employed to simulate the system of a\nnanostructure tunnel junction with any number of one-particle energy levels.\nThe tunneling current, including both shell-tunneling and shell-filling cases,\nis theoretically investigated via the nonequilibrium Green's function method.\nWe obtain a closed form for the spectral function, which is used to analyze the\ncomplicated tunneling current spectra of a quantum dot or molecule embedded in\na double-barrier junction. We also show that negative differential conductance\ncan be observed in a quantum dot tunnel junction when the Coulomb interactions\nwith neighboring quantum dots are taken into account."
    },
    {
        "anchor": "Implications of a temperature-dependent magnetic anisotropy for\n  superparamagnetic switching: The macroscopic magnetic moment of a superparamagnetic system has to overcome\nan energy barrier in order to switch its direction. This barrier is formed by\nmagnetic anisotropies in the material and may be surmounted typically after\n10^9 to 10^12 attempts per second by thermal fluctuations. In a first step, the\nassociated switching rate may be described by a Neel-Brown-Arrhenius law, in\nwhich the energy barrier is assumed as constant or a given temperature. Yet,\nmagnetic anisotropies in general depend on temperature themselves which is\nknown to modify the Neel-Brown-Arrhenius law. We illustrate quantitatively the\nimplications of a temperature-dependent anisotropy on the switching rate and in\nparticular for the interpretation of the prefactor as an attempt frequency. In\nparticular, we show that realistic numbers for the attempt frequency are\nobtained when the temperature dependence of the anisotropy is taken into\naccount.",
        "positive": "Quantum Superposition States of Two Valleys in Graphene: A system in a quantum superposition of distinct states usually exhibits many\npeculiar behaviors. Here we show that putting quasiparticles of graphene into\nsuperpositions of states in the two valleys can complete change the properties\nof the massless Dirac fermions. Due to the coexistence of both the quantum and\nrelativistic characteristics, the superposition states exhibit many oddball\nbehaviors in their chiral tunneling process. We further demonstrate that a\nrecently observed line defect in graphene could be used to generate such\nsuperposition states. A possible experimental device to detect the novel\nbehaviors of the relativistic superposition states in graphene is proposed."
    },
    {
        "anchor": "Parallel Transport of Electrons in Graphene Parallels Gravity: Geometrically a crystal containing dislocations and disclinations can be\nenvisaged as a `fixed frame' Cartan--Einstein space-time carrying torsion and\ncurvature, respectively. We demonstrate that electrons in defected graphene are\ntransported in the same way as fundamental Dirac fermions in a non-trivial 2+1\ndimensional space-time, with the proviso that the graphene electrons remember\nthe lattice constant through the valley quantum numbers. The extra `valley\nholonomy' corresponds to modified Euclidean symmetry generators.",
        "positive": "Intrinsic Spin Hall Effect Induced by Quantum Phase Transition in HgCdTe\n  Quantum Wells: Spin Hall effect can be induced both by the extrinsic impurity scattering and\nby the intrinsic spin-orbit coupling in the electronic structure. The HgTe/CdTe\nquantum well has a quantum phase transition where the electronic structure\nchanges from normal to inverted. We show that the intrinsic spin Hall effect of\nthe conduction band vanishes on the normal side, while it is finite on the\ninverted side. This difference gives a direct mechanism to experimentally\ndistinguish the intrinsic spin Hall effect from the extrinsic one."
    },
    {
        "anchor": "Design of GaAs-based valley phononic crystals with multiple complete\n  phononic bandgaps at ultra-high frequency: We report the design of GaAs-based monolithic valley phononic crystals\n(VPnCs) with multiple complete phononic bandgaps, which support simultaneous\nvalley-protected edge states with different symmetries in the gigahertz (GHz)\nrange. Rotation of triangular holes in the unit cells breaks the mirror\nsymmetry, and this orientation degree of freedom enables the structures to\nexhibit different valley vortex chiralities. We numerically demonstrate the\ntransport of multi-band valley-protected edge states with suppressed\nbackscattering at the sharp corners of the interfaces between different VPnCs.\nSuch monolithic semiconductor structures pave the way for ultra-high frequency\ntopological nanophononic applications by using the lithographic technique.",
        "positive": "Experimental Demonstration of Fermi Surface Effects at Filling Factor\n  5/2: Using small wavelength surface acoustic waves (SAW) on ultra-high mobility\nheterostructures, Fermi surface properties are detected at 5/2 filling factor\nat temperatures higher than those at which the quantum Hall state forms. An\nenhanced conductivity is observed at 5/2 by employing sub 0.5 micron wavelength\nSAW, indicating a quasiparticle mean-free-path substantially smaller than that\nin the lowest Landau level. These findings are consistent with the presence of\na filled Fermi sea of composite fermions, which may pair at lower temperatures\nto form the 5/2 ground state."
    },
    {
        "anchor": "Trions in coupled quantum wells and Wigner crystallization: We consider a restricted three body problem, where two interacted particles\nare located in two dimensional (2D) plane and interact with the third one\nlocated in the parallel spatially separated plane. The system of such type can\nbe formed in the semiconductor coupled quantum wells, where the electrons (or\nholes) and direct excitons spatially separated in different parallel\nneighboring quantum wells that are sufficiently close to interact and form\nnegative X- or positive X+ indirect trions. It is shown that at large interwell\nseparations, when the interwell separation much greater than the exciton Bohr\nradius, this problem can be solved analytically using the cluster approach.\nAnalytical results for the energy spectrum and the wave functions of the\nspatially indirect trion are obtained, their dependence on the interwell\nseparations is analyzed and a conditional probability distribution is\ncalculated. The formation of 2D Wigner crystal of trions at the low densities\nis predicted. It is shown that the critical density of the formation of the\ntrion Wigner crystal is sufficiently greater than the critical density of the\nelectron Wigner crystal.",
        "positive": "Skyrme crystal in bilayer and multilayer graphene: The ground state of the two-dimensional electron systems in Bernal bilayer\nand ABC-stacked multilayer graphenes in the presence of a strong magnetic field\nis investigated with the Hartree-Fock approximation. Phase diagrams of the\nsystems are obtained, focusing on charge density wave states including states\nwith vortices of valley pseudospins (called a Skyrme crystal). The\nsingle-electron states in these stacked graphenes are given by two-component\nwave functions. That of the first excited Landau level has the same component\nas the lowest Landau level of the ordinary two-dimensional electrons. Because\nof this localized wave functions, the Skyrme crystal has low energy in this\nfirst excited level up to four layers of graphene, when the inter-layer\ndistance is assumed to be infinitesimal. At the same time, bubble crystals are\nsuppressed, so the phase diagram is different from that of a single-layer\ngraphene."
    },
    {
        "anchor": "Ultrafast x-ray diffraction studies of photoexcited coherent phonons in\n  SrRuO$_3$ thin films: We present ultrafast x-ray diffraction experiments on thin films of metallic\nSrRuO$_3$ (SRO) after their excitation with ultrashort intense laser pulses.\nDepending on the layer thickness, the data exhibit a transient splitting of the\n(002) SRO Bragg peak evidencing the generation and propagation of sharp\nacoustic strain waves. These distinct structural dynamics are due to the\nexceptionally fast electron-phonon relaxation that gives rise to a\nquasi-instantaneous thermal stress in SRO. The interpretation is corroborated\nby numerical simulations which show excellent agreement with the experimental\nfindings. Despite the qualitatively different lattice dynamics for different\nSRO layer thicknesses, we identify a universal evolution of the transient\naverage layer strain. The inferred discrepancy of the thermal stress profile\nfrom the excitation profile may hint toward a temperature-dependent effective\nGr\\\"uneisen parameter of SRO.",
        "positive": "Density, phase and coherence properties of a low dimensional\n  Bose-Einstein systems moving in a disordered potential: We present a detailed numerical study of the dynamics of a disordered\none-dimensional Bose-Einstein condensates in position and momentum space. We\nparticularly focus on the region where non-linearity and disorder\nsimultaneously effect the time propagation of the condensate as well as the\npossible interference between various parts of the matter wave. We report\noscillation between spatially extended and localized behavior for the\npropagating condensate which dies down with increasing non-linearity. We also\nreport intriguing behavior of the phase fluctuation and the coherence\nproperties of the matter wave. We also briefly compare these behavior with that\nof a two-dimensional condensate. We mention the relevance of our results to the\nrelated experiments on Anderson localization and indicate the possibility of\nfuture experiments"
    },
    {
        "anchor": "Microscopic theory to quantify the competing kinetic processes in\n  photoexcited surface-coupled quantum dots: We present a self-contained theoretical and computational framework for\ndynamics following photoexcitation in quantum dots near planar interfaces. A\nmicroscopic Hamiltonian parameterized by first principles calculations is\nmerged with a reduced density matrix formalism that allows for the prediction\nof time-dependent charge and energy transfer processes between the quantum dot\nand the electrode. While treating charge and energy transfer processes on an\nequal footing, the non-perturbative effects of sudden charge transitions on the\nFermi sea of the electrode are included. We illustrate the formalism with\ncalculations of an InAs quantum dot coupled to the Shockley state on an Au[111]\nsurface, and use it to concretely discuss the wide range of kinetics possible\nin these systems and their implications for photovoltaic systems and tunnel\njunction devices. We discuss the utility of this framework for the analysis of\nrecent experiments.",
        "positive": "Three dimensional two-band Floquet topological insulator with $Z_2$\n  index: We present a class of three dimensional (3D) two-band Floquet topological\ninsulators constructed from two-dimensional Floquet topological insulators with\na $Z$ topological index. It is shown that the 3D two-band Floquet topological\ninsulator has a $Z_2$ topological index, whose value can be obtained by\nnumerical calculations or by using a relation to the winding number. The\nclassification of the 3D $Z_2$ Floquet topological insulator, however, cannot\nbe attributed to the stable homotopy groups. Thus, it is an example outside the\nproposed K-theory classifications of Floquet topological insulators. We also\nanalyze the edge modes of the 3D $Z_2$ Floquet topological insulator and find\nthe parity of the number of edge modes reflects the bulk $Z_2$ index."
    },
    {
        "anchor": "Wigner crystal diode: We study the transport properties of a Wigner crystal in one- and\ntwo-dimensional asymmetric periodic potential. We show that the Aubry\ntransition takes place above a certain critical amplitude of potential with the\nsliding and pinned phase below and above the transition. Due to the asymmetry\nthe Aubry pinned phase is characterized by the diode charge transport of the\nWigner crystal. We argue that the recent experimental observations of Aubry\ntransition with cold ions and colloidal monolayers can be extended to\nasymmetric potentials making possible to observe Wigner crystal diode with\nthese physical systems and electrons on liquid helium.",
        "positive": "Majorana modes and transport across junctions of superconductors and\n  normal metals: We study Majorana modes and transport in one-dimensional systems with a\n$p$-wave superconductor (SC) and normal metal leads. For a system with a SC\nlying between two leads, it is known that there is a Majorana mode at the\njunction between the SC and each lead. If the $p$-wave pairing $\\Delta$ changes\nsign or if a strong impurity is present at some point inside the SC, two\nadditional Majorana modes appear near that point. We study the effect of all\nthese modes on the sub-gap conductance between the leads and the SC. We derive\nan analytical expression as a function of $\\Delta$ and the length $L$ of the SC\nfor the energy shifts of the Majorana modes at the junctions due to\nhybridization between them; the shifts oscillate and decay exponentially as $L$\nis increased. The energy shifts exactly match the location of the peaks in the\nconductance. Using bosonization and the renormalization group method, we study\nthe effect of interactions between the electrons on $\\Delta$ and the strengths\nof an impurity inside the SC or the barriers between the SC and the leads; this\nin turn affects the Majorana modes and the conductance. Finally we propose a\nnovel experimental realization of these systems, in particular of a system\nwhere $\\Delta$ changes sign at one point inside the SC."
    },
    {
        "anchor": "Possible Reentrance of the Fractional Quantum Hall Effect in the Lowest\n  Landau Level: In the framework of a recently developed model of interacting composite\nfermions, we calculate the energy of different solid and Laughlin-type liquid\nphases of spin-polarized composite fermions. The liquid phases have a lower\nenergy than the competing solids around the electronic filling factors\nnu=4/11,6/17, and 4/19 and may thus be responsible for the fractional quantum\nHall effect at nu=4/11. The alternation between solid and liquid phases when\nvarying the magnetic field may lead to reentrance phenomena in analogy with the\nobserved reentrant integral quantum Hall effect.",
        "positive": "Hourglass semimetals with nonsymmorphic symmetries in three dimensions: It was recently shown that nonsymmorphic space group symmetries can protect\nnovel surface states with hourglass-like dispersions. In this paper, we show\nthat such dispersions can also appear in the bulk of three-dimensional (3D)\nsystems which respect nonsymmorphic symmetries. Specifically, we construct 3D\nlattice models featuring hourglass-like dispersions in the bulk, which are\nprotected by nonsymmorphic and time-reversal symmetries. We call such systems\nhourglass semimetals, as they have point or line nodes associated with\nhourglass-like dispersions. Hourglass nodal lines appear in glide-invariant\nplanes, while hourglass Weyl points can occur on screw-invariant axes. The Weyl\npoints and surface Fermi arcs in hourglass Weyl semimetals are stable against\nweak perturbations breaking those nonsymmorphic symmetries. Our results may\nshed light on searching for exotic Weyl semimetals in nonsymmorphic materials."
    },
    {
        "anchor": "Nuclear Spin Qubit Dephasing Time in the Integer Quantum Hall Effect\n  Regime: We report the first theoretical estimate of the nuclear-spin dephasing time\nT_2 owing to the spin interaction with the two-dimensional electron gas, when\nthe latter is in the integer quantum Hall state, in a two-dimensional\nheterojunction or quantum well at low temperature and in large applied magnetic\nfield. We establish that the leading mechanism of dephasing is due to the\nimpurity potentials that influence the dynamics of the spin via virtual\nmagnetic spin-exciton scattering. Implications of our results for\nimplementation of nuclear spins as quantum bits (qubits) for quantum computing\nare discussed.",
        "positive": "Boundaries of boundaries: a systematic approach to lattice models with\n  solvable boundary states of arbitrary codimension: We present a generic and systematic approach for constructing D-dimensional\nlattice models with exactly solvable d-dimensional boundary states localized to\ncorners, edges, hinges and surfaces. These solvable models represent a class of\n\"sweet spots\" in the space of possible tight-binding models---the exact\nsolutions remain valid for any tight-binding parameters as long as they obey\nsimple locality conditions that are manifest in the underlying lattice\nstructure. Consequently, our models capture the physics of both (higher-order)\ntopological and non-topological phases as well as the transitions between them\nin a particularly illuminating and transparent manner."
    },
    {
        "anchor": "Time-resolved spectroscopy at surfaces and adsorbate dynamics: insights\n  from a model-system approach: We introduce a model description of femtosecond laser induced desorption at\nsurfaces. The substrate part of the system is taken into account as a (possibly\nsemi-infinite) linear chain. Here, being especially interested in the early\nstages of dissociation, we consider a finite-size implementation of the model\n(i.e., a finite substrate), for which an exact numerical solution is possible.\nBy time-evolving the many-body wave function, and also using results from a\ntime-dependent density functional theory description for electron-nuclear\nsystems, we analyze the competition between several surface-response mechanisms\nand electronic correlations in the transient and longer time dynamics under the\ninfluence of dipole-coupled fields. Our model allows us to explore how coherent\nmultiple-pulse protocols can impact desorption in a variety of prototypical\nexperiments.",
        "positive": "Optical Probing of the Spin Polarization of the nu=5/2 Quantum Hall\n  State: We apply polarization resolved photoluminescence spectroscopy to measure the\nspin polarization of a two dimensional electron gas in perpendicular magnetic\nfield. In the vicinity of filling factor nu=5/2, we observe a sharp\ndiscontinuity in the energy of the zero Landau level emission line. We find\nthat the splitting between the two circular polarizations exhibits a sharp drop\nat nu=5/2 and is equal to the bare Zeeman energy, which resembles the behavior\nat even filling factors. We show that this behavior is consistent with filling\nfactor nu=5/2 being unpolarized."
    },
    {
        "anchor": "Skipping and snake orbits of electrons: singularities and catastrophes: Near the sample edge, or a sharp magnetic field step the drift of\ntwo-dimensional electrons in a magnetic field has the form of skipping/snake\norbits. We show that families of skipping/snake orbits of electrons injected at\none point inside a 2D metal generically exhibit caustics folds, cusps and cusp\ntriplets, and, in one extreme case, a section of the batterfly bifurcation.\nPeriodic appearance of singularities along the $\\pm B$-interface leads to the\nmagneto-oscillations of nonlocal conductance in multi-terminal electronic\ndevices.",
        "positive": "The Josephson critical current in a long mesoscopic S-N-S junction: We carry out an extensive experimental and theoretical study of the Josephson\neffect in S-N-S junctions made of a diffusive normal metal (N) embedded between\ntwo superconducting electrodes (S). Our experiments are performed on Nb-Cu-Nb\njunctions with highly-transparent interfaces. We give the predictions of the\nquasiclassical theory in various regimes on a precise and quantitative level.\nWe describe the crossover between the short and the long junction regimes and\nprovide the temperature dependence of the critical current using dimensionless\nunits $eR_{N}I_{c}/\\epsilon_{c}$ and $k_{B}T/\\epsilon_{c}$ where $\\epsilon_{c}$\nis the Thouless energy. Experimental and theoretical results are in excellent\nquantitative agreement."
    },
    {
        "anchor": "Critical Conductance of a Mesoscopic System: Interplay of the Spectral\n  and Eigenfunction Correlations at the Metal-Insulator Transition: We study the system-size dependence of the averaged critical conductance\n$g(L)$ at the Anderson transition. We have: (i) related the correction $\\delta\ng(L)=g(\\infty)-g(L)\\propto L^{-y}$ to the spectral correlations; (ii) expressed\n$\\delta g(L)$ in terms of the quantum return probability; (iii) argued that\n$y=\\eta$ -- the critical exponent of eigenfunction correlations. Experimental\nimplications are discussed.",
        "positive": "Fluorescence Intermittency of A Single Quantum System and Anderson\n  Localization: The nature of fluorescence intermittency for semiconductor quantum dots (QD)\nand single molecules (SM) is proposed as a manifestation of Anderson\nlocalization. The power law like distribution for the \\emph{on} time is\nexplained as due to the interaction between QD/SM with a random environment. In\nparticular, we find that the \\emph{on}-time probability distribution behaves\ndifferently in localized and delocalized regimes. They, when properly scaled,\nare \\emph{universal} for different QD/SM systems. The \\emph{on}-time\nprobability distribution function in the delocalized QD/SM regime can be\napproximated by power laws with exponents covering $-2\\le m <0$. QD/SM switches\nto a dark (\\emph{off}) state when a charge of QD/SM hops into the trap states,\nwhich becomes localized after stabilization by the surrounding matrix."
    },
    {
        "anchor": "Lasing and transport in a multi-level double quantum dot system coupled\n  to a microwave oscillator: We study a system of two quantum dots, each with several discrete levels,\nwhich are coherently coupled to a microwave oscillator. They are attached to\nelectronic leads and coupled to a phonon bath, both leading to inelastic\nprocesses. For a simpler system with a single level in each dot it has been\nshown that a population inversion can be created by electron tunneling, which\nin a resonance situation leads to lasing-type properties of the oscillator. In\nthe multi-level system several resonance situations may arise, some of them\nrelying on a sequence of tunneling processes which also involve non-resonant,\ninelastic transitions. The resulting photon number in the oscillator and the\ncurrent-voltage characteristic are highly sensitive to these properties and\naccordingly can serve as a probe for microscopic details.",
        "positive": "Valley-Polarized Exciton Dynamics in Exfoliated Monolayer WSe$_2$: Semiconducting transition metal dichalcogenide monolayers have emerged as\npromising candidates for future valleytronics-based quantum information\ntechnologies. Two distinct momentum-states of tightly-bound electron-hole pairs\nin these materials can be deterministically initialized via irradiation with\ncircularly polarized light. Here, we investigate the ultrafast dynamics of such\na valley polarization in monolayer tungsten diselenide by means of\ntime-resolved Kerr reflectometry. The observed Kerr signal in our sample stems\nexclusively from charge-neutral excitons. Our findings support the picture of a\nfast decay of the valley polarization of bright excitons due to radiative\nrecombination, intra-conduction-band spin-flip transitions,\nintervalley-scattering processes, and the formation of long-lived\nvalley-polarized dark states."
    },
    {
        "anchor": "Bond Algebras and Exact Solvability of Hamiltonians: Spin S=1/2\n  Multilayer Systems and Other Curiosities: We introduce an algebraic methodology for designing exactly-solvable Lie\nmodel Hamiltonians. The idea consists in looking at the algebra generated by\nbond operators. We illustrate how this method can be applied to solve numerous\nproblems of current interest in the context of topological quantum order. These\ninclude Kitaev's toric code and honeycomb models, a vector exchange model, and\na Clifford gamma model on a triangular lattice.",
        "positive": "Current noise, electron-electron interactions, and quantum interference: It is shown that electron-electron interactions lead to a novel\nquantum-interference contribution to non-equilibrium current noise in\nmesoscopic conductors. The corresponding noise spectrum is obtained in detail\nfor diffusive systems. It is found to be quadratic in the applied voltage and\nto exhibit a power-law frequency spectrum whose exponent depends on the\ndimensionality of the sample."
    },
    {
        "anchor": "Experiments on thermoelectric properties of quantum dots: Quantum dots (QDs) are good model systems for fundamental studies of\nmesoscopic transport phenomena using thermoelectric effects because of their\nsmall size, electrostatically tunable properties and thermoelectric response\ncharacteristics that are very sensitive to small thermal biases. Here we\nprovide a review of experimental studies on thermoelectric properties of single\nQDs realized in two-dimensional electron gases, single-walled carbon nanotubes\nand semiconductor nanowires. A key requirement for such experiments is methods\nfor nanoscale thermal biasing. We briefly review the main techniques used in\nthe field, namely, heating of the QD contacts, side heating and top heating,\nand touch upon their relative advantages. The thermoelectric response of a QD\nas a function of gate potential has a characteristic oscillatory behavior with\nthe same period as is observed for conductance peaks. Much of the existing\nliterature focuses on the agreement between experiments and theory,\nparticularly for amplitude and line-shape of the thermovoltage $V_{th}$. A\ngeneral observation is that the widely used single-electron tunneling\napproximation for QDs has limited success in reproducing measured $V_{th}$.\nLandauer-type calculations are often found to describe measurement results\nbetter despite the large electron-electron interactions in QDs. More recently,\nnonlinear thermoelectric effects have moved into the focus of attention and we\noffer a brief overview of experiments done so far. We conclude by discussing\nopen questions and avenues for future work, including the role of asymmetries\nin tunnel- and capacitive couplings in thermoelectric behavior of QDs.",
        "positive": "Collective luminescence and phonon-induced processes in double quantum\n  dots: We study the evolution of a quantum state of a double quantum dot system\ninteracting with the electromagnetic environment and with the lattice modes, in\nthe presence of a coupling between the two dots. We propose a unified approach\nto the simulation of the system evolution under joint impact of the two\nreservoirs. We discuss the sub- and superradiant radiative decay of the system,\nthe phonon-induced decay of entanglement between the dots, and the transfer of\nexcitation between them."
    },
    {
        "anchor": "Tip-Induced Molecule Anchoring in Ni-Phthalocyanine on Au(111) Substrate: Pinning single molecules at desired positions can provide opportunities to\nfabricate bottom-up designed molecular machines. Using the combined approach of\nscanning tunneling microscopy and density functional theory, we report on\ntip-induced anchoring of Niphthalocyanine molecules on an Au(111) substrate. We\ndemonstrate that the tip-induced current leads to the dehydrogenation of a\nbenzene-like ligand in the molecule, which subsequently creates chemical bonds\nbetween the molecule and the substrate. It is also found that the diffusivity\nof Ni-phthalocyanine molecules is dramatically reduced when the molecules are\nanchored on the Au adatoms produced by bias pulsing. The tip-induced molecular\nanchoring would be readily applicable to other functional molecules that\ncontain similar ligands.",
        "positive": "Strongly anisotropic spin relaxation in graphene/transition metal\n  dichalcogenide heterostructures at room temperature: Graphene has emerged as the foremost material for future two-dimensional\nspintronics due to its tuneable electronic properties. In graphene, spin\ninformation can be transported over long distances and, in principle, be\nmanipulated by using magnetic correlations or large spin-orbit coupling (SOC)\ninduced by proximity effects. In particular, a dramatic SOC enhancement has\nbeen predicted when interfacing graphene with a semiconducting transition metal\ndechalcogenide, such as tungsten disulphide (WS$_2$). Signatures of such an\nenhancement have recently been reported but the nature of the spin relaxation\nin these systems remains unknown. Here, we unambiguously demonstrate\nanisotropic spin dynamics in bilayer heterostructures comprising graphene and\nWS$_2$. By using out-of-plane spin precession, we show that the spin lifetime\nis largest when the spins point out of the graphene plane. Moreover, we observe\nthat the spin lifetime varies over one order of magnitude depending on the spin\norientation, indicating that the strong spin-valley coupling in WS$_2$ is\nimprinted in the bilayer and felt by the propagating spins. These findings\nprovide a rich platform to explore coupled spin-valley phenomena and offer\nnovel spin manipulation strategies based on spin relaxation anisotropy in\ntwo-dimensional materials."
    },
    {
        "anchor": "Moving Wigner Glasses and Smectics: Dynamics of Disordered Wigner\n  Crystals: We examine the dynamics of driven classical Wigner solids interacting with\nquenched disorder from charged impurities. For strong disorder, the initial\nmotion is plastic -- in the form of crossing winding channels. For increasing\ndrive, the disordered Wigner glass can reorder to a moving Wigner smectic --\nwith the electrons moving in non-crossing 1D channels. These different dynamic\nphases can be related to the conduction noise and I(V) curves. For strong\ndisorder, we show criticality in the voltage onset just above depinning. We\nalso obtain the dynamic phase diagram for driven Wigner solids and prove that\nthere is a finite threshold for transverse sliding, recently found\nexperimentally.",
        "positive": "Isospin competitions and valley polarized correlated insulators in\n  twisted double bilayer graphene: New phase of matter usually emerges when a given symmetry breaks\nspontaneously, which can involve charge, spin, and valley degree of freedoms.\nHere, we report an observation of new correlated insulators evolved from spin\npolarized states to valley polarized states in AB-BA stacked twisted double\nbilayer graphene (TDBG). The transition of the isospin polarization is a result\nof the competition between spin and valley, driven by the displacement field\n(D). At a high field |D| > 0.7 V/nm, we observe valley polarized correlated\ninsulators with a big Zeeman g factor of ~10, both at v = 2 in the moir\\'e\nconduction band and more surprisingly at v = -2 in the moir\\'e valence band. At\na medium field |D| < 0.6 V/nm, by contrast, it is a conventional spin polarized\ncorrelated insulator at v = 2 and a featureless metal at v = -2. Moreover, we\nobserve a valley polarized Chern insulator with C = 2 emanating at v = 2 in the\nelectron side and a valley polarized Fermi surface around v = -2 in the hole\nside. The valley Chern insulator with C = 2 is evident from a well quantized\nHall conductance plateau at 2e^2/h and correspondingly a vanishing longitudinal\ncomponent. The valley polarized Fermi surface is topologically trivial with C =\n0, and it shows a series of quantized Landau levels with v_LL = 0, 1, 2, 3, 4\nand others. These observations are in good agreements with our band and\ntopology calculations. Our results demonstrate a feasible way to realize\nisospin control and to obtain new phases of matter in TDBG by the displacement\nfield, and might benefit other twisted or non-twisted multilayer systems."
    },
    {
        "anchor": "Spin-valley lifetimes in a silicon quantum dot with tunable valley\n  splitting: Although silicon is a promising material for quantum computation, the\ndegeneracy of the conduction band minima (valleys) must be lifted with a\nsplitting sufficient to ensure formation of well-defined and long-lived spin\nqubits. Here we demonstrate that valley separation can be accurately tuned via\nelectrostatic gate control in a metal-oxide-semiconductor quantum dot,\nproviding splittings spanning 0.3 - 0.8 meV. The splitting varies linearly with\napplied electric field, with a ratio in agreement with atomistic tight-binding\npredictions. We demonstrate single-shot spin readout and measure the spin\nrelaxation for different valley configurations and dot occupancies, finding\none-electron lifetimes exceeding 2 seconds. Spin relaxation occurs via phonon\nemission due to spin-orbit coupling between the valley states, a process not\npreviously anticipated for silicon quantum dots. An analytical theory describes\nthe magnetic field dependence of the relaxation rate, including the presence of\na dramatic rate enhancement (or hot-spot) when Zeeman and valley splittings\ncoincide.",
        "positive": "Topological Kondo effect with Majorana fermions: The Kondo effect is a striking consequence of the coupling of itinerant\nelectrons to a quantum spin with degenerate energy levels. While degeneracies\nare commonly thought to arise from symmetries or fine-tuning of parameters, the\nrecent emergence of Majorana fermions has brought to the fore an entirely\ndifferent possibility: a \"topological degeneracy\" which arises from the\nnonlocal character of Majorana fermions. Here we show that nonlocal quantum\nspins formed from these degrees of freedom give rise to a novel \"topological\nKondo effect\". This leads to a robust non-Fermi liquid behavior, known to be\ndifficult to achieve in the conventional Kondo context. Focusing on mesoscopic\nsuperconductor devices, we predict several unique transport signatures of this\nKondo effect, which would demonstrate the non-local quantum dynamics of\nMajorana fermions, and validate their potential for topological quantum\ncomputation."
    },
    {
        "anchor": "Fractional quantum Hall edge polaritons: It is commonly believed that light cannot couple to the collective\nexcitations of the fractional quantum Hall effect (FQHE). This assumption\nrelies on Kohn's theorem that states that electron-electron interactions\ndecouple from homogeneous electromagnetic fields due to Galilean invariance.\nHere, we demonstrate that in finite systems light-matter coupling beyond the\ndipole approximation breaks Kohn's theorem, and enables the coupling of cavity\nphotons to the plasmonic edge modes of the FQHE. We derive the coupling using\nthe FQHE bulk-boundary correspondence and predict the formation of\nexperimentally detectable plasmon polaritons. In conjunction with recent\nexperiments, we find that a single cavity mode leaves the system's topological\nprotection intact. Interestingly, however, a multimode cavity mediates plasmon\nbackscattering and effectively transforms the edges of the 2D FQHE into a 1D\nwire. Such cavity-meditated nonlocal backscattering bodes the breakdown of the\ntopological protection in the regime of ultra-strong photon-plasmon coupling.\nOur analytical framework and findings pave the way for investigating the\ntopological order of the FQHE via optical spectroscopic probes as well as\nprovide new opportunities to control FQHE edge excitations using light.",
        "positive": "Screening effect in Spin-Hall Devices: The stationary state of the spin-Hall bar is studied in the framework of a\nvariational approach that includes non-equilibrium screening effects. The\nminimization of the power dissipated in the system is performed with taking\ninto account the spin-flip relaxation and the global constrains due to the\nelectric generator and global charge conservation. The calculation is performed\nin both approximations of negligible spin-flip scattering and strong spin-flip\nscattering. In both cases, the expressions of the spin-accumulation and the\nlongitudinal and transverse pure spin-currents are derived analytically. Due to\nthe small value of the Debye-Fermi screening length, the spin-accumulation is\nshown to be linear in $y$ (across the device), linear in the electric field\nimposed by the generator, and inversely proportional to the temperature for\nnon-degenerate conductors."
    },
    {
        "anchor": "Accuracy of density functionals for molecular electronics: the Anderson\n  junction: The exact ground-state exchange-correlation functional of Kohn-Sham density\nfunctional theory yields the exact transmission through an Anderson junction at\nzero bias and temperature. The exact impurity charge susceptibility is used to\nconstruct the exact exchange-correlation potential. We analyze the successes\nand limitations of various types of approximations, including smooth and\ndiscontinuous functionals of the occupation, as well as symmetry-broken\napproaches.",
        "positive": "Gate control of the spin mobility through the modification of the\n  spin-orbit interaction in two-dimensional systems: Spin drag measurements were performed in a two-dimensional electron system\nset close to the crossed spin helix regime and coupled by strong intersubband\nscattering. In a sample with uncommon combination of long spin lifetime and\nhigh charge mobility, the drift transport allows us to determine the spin-orbit\nfield and the spin mobility anisotropies. We used a random walk model to\ndescribe the system dynamics and found excellent agreement for the Rashba and\nDresselhaus couplings. The proposed two-subband system displays a large tuning\nlever arm for the Rashba constant with gate voltage, which provides a new path\ntowards a spin transistor. Furthermore, the data shows large spin mobility\ncontrolled by the spin-orbit constants setting the field along the direction\nperpendicular to the drift velocity. This work directly reveals the resistance\nexperienced in the transport of a spin-polarized packet as a function of the\nstrength of anisotropic spin-orbit fields."
    },
    {
        "anchor": "Magnetic impurity formation in quantum point contacts: A quantum point contact (QPC), a narrow region separating two wider electron\nreservoirs, is the standard building block of sub-micron devices, such as\nquantum dots - small boxes of electrons, and qubits - the proposed basic\nelements of quantum computers. As a function of its width, the conductance\nthrough a QPC changes in integer steps of G0 = $2e^2/h$, signalling the\nquantization of its tranverse modes.1,2 Such measurements also reveal an\nadditional shoulder at a value around 0.7, an observation which remains a\npuzzle even after more than a decade. Recently it has been suggested5,6 that\nthis phenomenon can be explained if one invokes the existence of a magnetic\nimpurity in the QPC at low densities. Here we present extensive numerical\ndensity-functional calculations that reveal the formation of a magnetic moment\nin the channel as the density increases above pinch-off, under very general\nconditions. In addition we show that such an impurity will also form at large\nmagnetic fields, for a specific value of the field (corresponding to a\ndegeneracy point between the upper spin state in the first mode and the lower\nspin state in the second mode), and sometimes even at the opening of the second\nmode in the QPC. Beyond explaining the source of the \"0.7 anomaly\", these\nresults may have far reaching implications on spin filling of electronic states\nin quantum dots and on dephasing of quantum information stored in semiconductor\nqubits.",
        "positive": "Single- and few-layer graphene growth on stainless steel substrates by\n  direct thermal chemical vapor deposition: Steeping interest on graphene research in basic sciences and applications\nemphasizes the need for an economical means of synthesizing it. We report a\nmethod for the synthesis of graphene on commercially available stainless steel\nfoils using direct thermal chemical vapor deposition. Our method of synthesis\nand the use of relatively cheap precursors such as ethanol (CH3CH2OH) as a\nsource of carbon and SS 304 as the substrate, proved to be economically viable.\nPresence of single- and few-layer graphene was confirmed using confocal Raman\nmicroscopy/spectroscopy. X-ray photoelectron spectroscopic measurements were\nfurther used to establish the influence of various elemental species present in\nstainless steel on graphene growth. Role of cooling rate on surface migration\nof certain chemical species (oxides of Fe, Cr and Mn) that promote or hinder\nthe growth of graphene is probed. Such analysis of the chemical species present\non the surface can be promising for graphene based catalytic research."
    },
    {
        "anchor": "Winding number and Zak phase in multi-band SSH models: We use multi-band SSH models to demonstrate a prescription for calculating\nthe correct Zak phase and winding number of multi-band systems. We verify our\nprescription by comparing the resultant winding number of a four-band SSH model\nwith the edge states of a semi-infinite chain which we find by solving the\nequation of motion. We then also carry out an extensive comparison with the\nnumerical results obtained by solving the matrix eigenvalue problem of finite\nchains with various number of sites. As a double check of our prescription, we\nalso confirm the bulk edge correspondence in a six-band SSH model. Similar to\nthe usual SSH model, the winding numbers associated to the left and right\nboundaries in a finite chain may be different if space inversion symmetry is\nviolated in the system. We believe the prescription we propose here may also be\napplied to other 1D multi-band systems.",
        "positive": "Nanomagnetism of magnetoelectric granular thin-film antiferromagnets: Antiferromagnets have recently emerged as attractive platforms for\nspintronics applications, offering fundamentally new functionalities compared\nto their ferromagnetic counterparts. While nanoscale thin film materials are\nkey to the development of future antiferromagnetic spintronics technologies,\nexperimental tools to explore such films on the nanoscale are still sparse.\nHere, we offer a solution to this technological bottleneck, by addressing the\nubiquitous surface magnetisation of magnetoelectic antiferromagnets in a\ngranular thin film sample on the nanoscale using single-spin magnetometry in\ncombination with spin-sensitive transport experiments. Specifically, we\nquantitatively image the evolution of individual nanoscale antiferromagnetic\ndomains in 200-nm thin-films of Cr$_2$O$_3$ in real space and across the\nparamagnet-to-antiferromagnet phase transition. These experiments allow us to\ndiscern key properties of the Cr$_2$O$_3$ thin film, including the mechanism of\ndomain formation and the strength of exchange coupling between individual\ngrains comprising the film. Our work offers novel insights into Cr$_2$O$_3$'s\nmagnetic ordering mechanism and establishes single spin magnetometry as a\nnovel, widely applicable tool for nanoscale addressing of antiferromagnetic\nthin films."
    },
    {
        "anchor": "Over-Barrier Photoelectron Emission with Rashba Spin-Orbit Coupling: We develop a theoretical model to calculate the quantum efficiency (QE) of\nphotoelectron emission from materials with Rashba spin-orbit coupling (RSOC)\neffect. In the low temperature limit, an analytical scaling between QE and the\nRSOC strength is obtained as QE $\\propto (\\hbar\\omega-W)^2+2E_R(\\hbar \\omega-W)\n-E_R^2/3$, where $\\hbar\\omega$, $W$ and $E_R$ are the incident photon energy,\nwork function and the RSOC parameter respectively. Intriguingly, the RSOC\neffect substantially improves the QE for strong RSOC materials. For example,\nthe QE of Bi$_2$Se$_3$ and Bi/Si(111) increases, by 149\\% and 122\\%,\nrespectively due to the presence of strong RSOC. By fitting to the\nphotoelectron emission characteristics, the analytical scaling law can be\nemployed to extract the RSOC strength, thus offering a useful tool to\ncharacterize the RSOC effect in materials. Importantly, when the traditional\nFowler-Dubridge model is used, the extracted results may substantially deviate\nfrom the actual values by $\\sim90\\%$, thus highlighting the importance of\nemploying our model to analyse the photoelectron emission especially for\nmaterials with strong RSOC. These findings provide a theoretical foundation for\nthe design of photoemitters using Rashba spintronic materials.",
        "positive": "Onset voltage shift due to non-zero Landau ground state level in\n  coherent magnetotransport: Coherent electron transport in double-barrier heterostructures with parallel\nelectric and magnetic fields is analyzed theoretically and with the aid of a\nquantum simulator accounting for 3-dimensional transport effects. The\nonset-voltage shift induced by the magnetic field in resonant tunneling diodes,\nwhich was previously attributed to the cyclotron frequency $w_c$ inside the\nwell is found to arise from an upward shift of the non-zero ground (lowest)\nLandau state energy in the entire quantum region where coherent transport takes\nplace. The spatial dependence of the cyclotron frequency is accounted for and\nverified to have a negligible impact on resonant tunneling for the device and\nmagnetic field strength considered. A correction term for the onset-voltage\nshift arising from the magnetic field dependence of the chemical potential is\nalso derived. The Landau ground state with its nonvanishing finite harmonic\noscillator energy $ \\hbar w_c /2$ is verified however to be the principal\ncontributor to the onset voltage shift at low temperatures."
    },
    {
        "anchor": "Fast charge sensing of a cavity-coupled double quantum dot using a\n  Josephson parametric amplifier: We demonstrate fast readout of a double quantum dot (DQD) that is coupled to\na superconducting resonator. Utilizing parametric amplification in a nonlinear\noperational mode, we improve the signal-to-noise ratio (SNR) by a factor of\n2000 compared to the situation with the parametric amplifier turned off. With\nan integration time of 400 ns we achieve a SNR of 76. By studying SNR as a\nfunction of the integration time we extract an equivalent charge sensitivity of\n8 x 10^{-5} e/root(Hz). The high SNR allows us to acquire a DQD charge\nstability diagram in just 20 ms. At such a high data rate, it is possible to\nacquire charge stability diagrams in a live \"video-mode,\" enabling real time\ntuning of the DQD confinement potential.",
        "positive": "Phase transitions in two tunnel-coupled HgTe quantum wells. Bilayer\n  graphene analogy and beyond: HgTe quantum wells possess remarkable physical properties as for instance the\nquantum spin Hall state and the 'single-valley' analog of graphene, depending\non their layer thicknesses and barrier composition. However, double HgTe\nquantum wells yet contain more fascinating and still unrevealed features. Here\nwe report on the study of the quantum phase transitions in tunnel-coupled HgTe\nlayers separated by CdTe barrier. We demonstrate that this system has a 3/2\npseudo spin degree of freedom, which features a number of particular properties\nassociated with the spin-dependent coupling between HgTe layers. We discover a\nspecific metal phase arising in a wide range of HgTe and CdTe layer\nthicknesses, in which a gapless bulk and a pair of helical edge states coexist.\nThis phase holds some properties of bilayer graphene such as an unconventional\nquantum Hall effect and an electrically-tunable band gap. In this 'bilayer\ngraphene' phase, electric field opens the band gap and drives the system into\nthe quantum spin Hall state. Furthermore, we discover a new type of quantum\nphase transition arising from a mutual inversion between second electron- and\nhole-like subbands. This work paves the way towards novel materials based on\nmulti-layered topological insulators."
    },
    {
        "anchor": "Theory of magnetotransport in shaped topological insulator nanowires: We show that shaped topological insulator (TI) nanowires, i.e. such that\ntheir cross-section radius varies along the wire length, can be tuned into a\nnumber of different transport regimes when immersed in a homogeneous coaxial\nmagnetic field. This is in contrast with widely studied tubular nanowires with\nconstant cross-section, and is due to magnetic confinement of Dirac surface\ncarriers. In flat 2D systems such a confinement requires non-homogeneous\nmagnetic fields, while for shaped nanowires of standard size homogeneous fields\nof the order of $B\\sim\\,1$T are sufficient. We put recent work [Kozlovsky et\nal., Phys. Rev. Lett. 124, 126804 (2020)] into broader context and extend it to\ndeal with axially symmetric wire geometries with arbitrary radial profile. A\ndumbbell-shaped TI nanowire is used as a paradigmatic example for transport\nthrough a constriction and shown to be tunable into five different transport\nregimes: (i) conductance steps, (ii) resonant transmission, (iii) current\nsuppression, (iv) Coulomb blockade, and (v) transport through a triple quantum\ndot. Switching between regimes is achieved by modulating the strength of a\ncoaxial magnetic field and does not require strict axial symmetry of the wire\ncross-section. As such, it should be observable in TI nanowires fabricated with\navailable experimental techniques.",
        "positive": "Quantum metric nonlinear Hall effect in a topological antiferromagnetic\n  heterostructure: Quantum geometry - the geometry of electron Bloch wavefunctions - is central\nto modern condensed matter physics. Due to the quantum nature, quantum geometry\nhas two parts, the real part quantum metric and the imaginary part Berry\ncurvature. The studies of Berry curvature have led to countless breakthroughs,\nranging from the quantum Hall effect in 2DEGs to the anomalous Hall effect\n(AHE) in ferromagnets. However, in contrast to Berry curvature, the quantum\nmetric has rarely been explored. Here, we report a new nonlinear Hall effect\ninduced by quantum metric by interfacing even-layered MnBi2Te4 (a PT-symmetric\nantiferromagnet (AFM)) with black phosphorus. This novel nonlinear Hall effect\nswitches direction upon reversing the AFM spins and exhibits distinct scaling\nthat suggests a non-dissipative nature. Like the AHE brought Berry curvature\nunder the spotlight, our results open the door to discovering quantum metric\nresponses. Moreover, we demonstrate that the AFM can harvest wireless\nelectromagnetic energy via the new nonlinear Hall effect, therefore enabling\nintriguing applications that bridges nonlinear electronics with AFM\nspintronics."
    },
    {
        "anchor": "Gap inversion in one-dimensional Andreev crystals: We study a periodic arrangement of magnetic regions in a one-dimensional\nsuperconducting wire. Due to the local exchange field, each region supports\nAndreev bound states that hybridize forming Bloch bands in the subgap spectrum\nof what we call the Andreev crystal (AC). As an illustration, ACs with\nferromagnetic and antiferromagnetic alignment of the magnetic regions are\nconsidered. We relate the spectral asymmetry index of a spin-resolved\nHamiltonian to the spin polarization and identify it as the observable that\nquantifies the closing and reopening of the excitation gap. In particular,\nantiferromagnetic ACs exhibit a sequence of gapped phases separated by gapless\nDirac phase boundaries. Heterojunctions between antiferromagnetic ACs in\nneighboring phases support spin-polarized bound states at the interface. In a\nclose analogy to the charge fractionalization in Dirac systems with a mass\ninversion, we find a fractionalization of the interface spin.",
        "positive": "Symmetric Complementary Logic Inverter Using Integrated Black Phosphorus\n  and MoS2 Transistors: The operation of an integrated two-dimensional complementary\nmetal-oxide-semiconductor inverter with well-matched input/output voltages is\nreported. The circuit combines a few-layer MoS2 n-MOSFET and a black phosphorus\n(BP) p-MOSFET fabricated using a common local backgate electrode with thin (20\nnm) HfO2 gate dielectric. The constituent devices have linear threshold\nvoltages of -0.8 V and +0.8 V and produce peak transconductances of 16 uS/um\nand 41 uS/um for the MoS2 n-MOSFET and BP p-MOSFET, respectively. The inverter\nshows a voltage gain of 3.5 at a supply voltage, VDD = 2.5 V, and has peak\nswitching current of 108 uA and off-state current of 8.4 uA (2.4 uA) at VIN = 0\n(VIN = 2.5 V). In addition, the inverter has voltage gain greater than unity\nfor VDD > 0.5 V, has open butterfly curves for VDD > 1 V, and achieves static\nnoise margin over 500 mV at VDD = 2.5 V. The voltage gain was found to be\ninsensitive to temperature between 270 K and 340 K, and AC large and\nsmall-signal operation was demonstrated at frequencies up to 100 kHz. The\ndemonstration of a complementary 2D inverter which operates in a symmetric\nvoltage window suitable for driving a subsequent logic stage is a significant\nstep forward in developing practical applications for devices based upon 2D\nmaterials."
    },
    {
        "anchor": "Hall Viscosity and Momentum Transport in Lattice and Continuum Models of\n  the Integer Quantum Hall Effect in Strong Magnetic Fields: The Hall viscosity describes a non-dissipative response to strain in systems\nwith broken time-reversal symmetry. We develop a new method for computing the\nHall viscosity of lattice systems in strong magnetic fields based on momentum\ntransport, which we compare to the method of momentum polarization used by Tu\net al. [Phys. Rev. B 88 195412 (2013)] and Zaletel et al. [Phys. Rev. Lett. 110\n236801 (2013)] for non-interacting systems. We compare the Hall viscosity of\nsquare-lattice tight-binding models in magnetic field to the continuum integer\nquantum Hall effect (IQHE) showing agreement when the magnetic length is much\nlarger than the lattice constant, but deviation as the magnetic field strength\nincreases. We also relate the Hall viscosity of relativistic electrons in\nmagnetic field (the Dirac IQHE) to the conventional IQHE. The Hall viscosity of\nthe lattice Dirac model in magnetic field agrees with the continuum Dirac Hall\nviscosity when the magnetic length is much larger than the lattice constant. We\nalso show that the Hall viscosity of the lattice model deviates further from\nthe continuum model if the $C_4$ symmetry of the square lattice is broken to\n$C_2$, but the deviation is again minimized as the magnetic length increases.",
        "positive": "Quantum Hall effect near the charge neutrality point in two-dimensional\n  electron-hole system: We study the transport properties of $HgTe$-based quantum wells containing\nsimultaneously electrons and holes in magnetic field B. At the charge\nneutrality point (CNP) with nearly equal electron and hole densities, the\nresistance is found to increase very strongly with B while the Hall resistivity\nturns to zero. This behavior results in a wide plateau in the Hall conductivity\n$\\sigma_{xy}\\approx 0$ and in a minimum of diagonal conductivity $\\sigma_{xx}$\nat $\\nu=\\nu_p-\\nu_n=0$, where $\\nu_n$ and $\\nu_p$ are the electron and hole\nLandau filling factors. We suggest that the transport at the CNP point is\ndetermined by electron-hole \"snake states\" propagating along the $\\nu=0$ lines.\nOur observations are qualitatively similar to the quantum Hall effect in\ngraphene as well as to the transport in random magnetic field with zero mean\nvalue."
    },
    {
        "anchor": "Bulk-edge coupling in the non-abelian $\u03bd=5/2$ quantum Hall\n  interferometer: Recent schemes for experimentally probing non-abelian statistics in the\nquantum Hall effect are based on geometries where current-carrying\nquasiparticles flow along edges that encircle bulk quasiparticles, which are\nlocalized. Here we consider one such scheme, the Fabry-Perot interferometer,\nand analyze how its interference patterns are affected by a coupling that\nallows tunneling of neutral Majorana fermions between the bulk and edge. While\nat weak coupling this tunneling degrades the interference signal, we find that\nat strong coupling, the bulk quasiparticle becomes essentially absorbed by the\nedge and the intereference signal is fully restored.",
        "positive": "Effects of the electrostatic environment on superlattice Majorana\n  nanowires: Finding ways of creating, measuring and manipulating Majorana bound states\n(MBSs) in superconducting-semiconducting nanowires is a highly pursued goal in\ncondensed matter physics. It was recently proposed that a periodic covering of\nthe semiconducting nanowire with superconductor fingers would allow both gating\nand tuning the system into a topological phase while leaving room for a local\ndetection of the MBS wavefunction. We perform a detailed, self-consistent\nnumerical study of a three-dimensional (3D) model for a finite-length nanowire\nwith a superconductor superlattice including the effect of the surrounding\nelectrostatic environment, and taking into account the surface charge created\nat the semiconductor surface. We consider different experimental scenarios\nwhere the superlattice is on top or at the bottom of the nanowire with respect\nto a back gate. The analysis of the 3D electrostatic profile, the charge\ndensity, the low energy spectrum and the formation of MBSs reveals a rich\nphenomenology that depends on the nanowire parameters as well as on the\nsuperlattice dimensions and the external back gate potential. The 3D\nenvironment turns out to be essential to correctly capture and understand the\nphase diagram of the system and the parameter regions where topological\nsuperconductivity is established."
    },
    {
        "anchor": "Topologically nontrivial magnonic solitons: The intrinsic non-linearities of the spin dynamics in condensed matter\nsystems give rise to a rich phenomenology that can be strongly affected by\ntopology. Here we study formation of magnonic solitons in the topologically\nnontrivial bandgap of a spin lattice realization of the Haldane model, in both\nstatic and dynamic (Floquet) regimes. We consider nonlinearities caused by\nmagnetic crystalline anisotropy and magnon-magnon interactions. We find soliton\nformation power thresholds as a function of anisotropy coefficient and\ninteraction strength. We predict different classes of topological solitons for\nthe same topological class of the underlying lattice and explain it in terms of\na transition from a topologically nontrivial mass to a trivial one. Our\nfindings imply that a soliton can phase-separate, containing boundaries between\ntopologically trivial and non-trivial phases, which is associated with a\nvanishing spin wave gap.",
        "positive": "Conserving approximations in time-dependent quantum transport: Initial\n  correlations and memory effects: We study time-dependent quantum transport in a correlated model system by\nmeans of time-propagation of the Kadanoff-Baym equations for the nonequilibrium\nmany-body Green function. We consider an initially contacted equilibrium system\nof a correlated central region coupled to tight-binding leads. Subsequently a\ntime-dependent bias is switched on after which we follow in detail the\ntime-evolution of the system. Important features of the Kadanoff-Baym approach\nare 1) the possibility of studying the ultrafast dynamics of transients and\nother time-dependent regimes and 2) the inclusion of exchange and correlation\neffects in a conserving approximation scheme. We find that initial correlation\nand memory terms due to many-body interactions have a large effect on the\ntransient currents. Furthermore the value of the steady state current is found\nto be strongly dependent on the approximation used to treat the electronic\ninteractions."
    },
    {
        "anchor": "Are quantum spin Hall edge modes more resilient to disorder, sample\n  geometry and inelastic scattering than quantum Hall edge modes?: On the surface of 2D Topological insulators occur 1D quantum spin Hall(QSH)\nedge modes with Dirac like dispersion. Unlike quantum Hall(QH) edge modes which\noccur at high magnetic fields in 2DEGs, the occurrence of QSH edge modes is\nbecause of spin-orbit scattering in the bulk of the material. These QSH edge\nmodes are spin dependent and chiral- opposite spins move in opposing\ndirections. Electronic spin has larger decoherence and relaxation time than\ncharge- in view of this its expected that QSH edge modes will be more robust to\ndisorder and inelastic scattering than QH edge modes which are charge dependent\nand spin unpolarized. However, we notice no such advantage accrues to QSH edge\nmodes when subjected to same degree of contact disorder and/or inelastic\nscattering in similar setups as QH edge modes. In fact we observe that QSH edge\nmodes are more susceptible to inelastic scattering and contact disorder than QH\nedge modes. Further, while a single disordered contact has no effect on QH edge\nmodes it leads to a finite charge Hall current in case of quantum spin Hall\nedge modes and thus vanishing of pure quantum spin Hall effect. For more than a\nsingle disordered contact while quantum Hall states continue to remain immune\nto disorder, quantum spin Hall edge modes become more susceptible- the Hall\nresistance for quantum spin Hall effect changes sign with increasing disorder.\nIn case of many disordered contacts with inelastic scattering included while\nquantization of Hall edge modes holds, for quantum spin Hall edge modes- a\nfinite charge Hall current still flows. For quantum spin Hall edge modes in the\ninelastic scattering regime we distinguish between two cases: with spin-flip\nand without spin-flip scattering. Finally, while asymmetry in sample geometry\ncan have a deleterious effect on quantum spin Hall case it has no impact in\nquantum Hall case.",
        "positive": "Strong and Tunable Spin Lifetime Anisotropy in Dual-Gated Bilayer\n  Graphene: We report the discovery of a strong and tunable spin lifetime anisotropy with\nexcellent spin lifetimes up to 7.8 ns in dual-gated bilayer graphene.\nRemarkably, this realizes the manipulation of spins in graphene by\nelectrically-controlled spin-orbit fields, which is unexpected due to\ngraphene's weak intrinsic spin-orbit coupling. We utilize both the in-plane\nmagnetic field Hanle precession and oblique Hanle precession measurements to\ndirectly compare the lifetimes of out-of-plane vs. in-plane spins. We find that\nnear the charge neutrality point, the application of a perpendicular electric\nfield opens a band gap and generates an out-of-plane spin-orbit field that\nstabilizes out-of-plane spins against spin relaxation, leading to a large spin\nlifetime anisotropy. This intriguing behavior occurs because of the unique\nspin-valley coupled band structure of bilayer graphene. Our results demonstrate\nthe potential for highly tunable spintronic devices based on dual-gated 2D\nmaterials."
    },
    {
        "anchor": "Reduced thermal stability of antiferromagnetic nanostructures: Antiferromagnetic materials hold promising prospects in novel types of\nspintronics applications. Assessing the stability of antiferromagnetic\nnanostructures against thermal excitations is a crucial aspect of designing\ndevices with a high information density. Here we use theoretical calculations\nand numerical simulations to determine the mean switching time of\nantiferromagnetic nanoparticles in the superparamagnetic limit. It is\ndemonstrated that the thermal stability is drastically reduced compared to\nferromagnetic particles in the limit of low Gilbert damping, attributed to the\nexchange enhancement of the attempt frequencies. It is discussed how the system\nparameters have to be engineered in order to optimize the switching rates in\nantiferromagnetic nanoparticles.",
        "positive": "Conductance Peak Density in Nanowires: We present a complete numerical calculation and an experimental data analysis\nof the universal conductance fluctuations in quasi-one-dimension nanowires. The\nconductance peak density model, introduced in nanodevice research on [Phys.\nRev. Lett. 107, 176807 (2011)], is applied successfully to obtain the coherence\nlength of InAs nanowire magnetoconductance and we prove its equivalence with\ncorrelation methods. We show the efficiency of the method and therefore a\nprominent alternative to obtain the phase-coherence length. The peak density\nmodel can be similarly applied to spintronic setups, graphene and topological\nisolator where phase-coherence length is a relevant experimental parameter."
    },
    {
        "anchor": "Spin dynamics in p-doped semiconductor nanostructures subject to a\n  magnetic field tilted from the Voigt geometry: We develop a theoretical description of the spin dynamics of resident holes\nin a p-doped semiconductor quantum well (QW) subject to a magnetic field tilted\nfrom the Voigt geometry. We find the expressions for the signals measured in\ntime-resolved Faraday rotation (TRFR) and resonant spin amplification (RSA)\nexperiments and study their behavior for a range of system parameters. We find\nthat an inversion of the RSA peaks can occur for long hole spin dephasing times\nand tilted magnetic fields. We verify the validity of our theoretical findings\nby performing a series of TRFR and RSA experiments on a p-modulation doped\nGaAs/Al_{0.3}Ga_{0.7}As single QW and showing that our model can reproduce\nexperimentally observed signals.",
        "positive": "Coulomb blockade and transport in a chain of one-dimensional quantum\n  dots: A long one-dimensional wire with a finite density of strong random impurities\nis modelled as a chain of weakly coupled quantum dots. At low temperature T and\napplied voltage V its resistance is limited by \"breaks\": randomly occuring\nclusters of quantum dots with a special length distribution pattern that\ninhibits the transport. Due to the interplay of interaction and disorder\neffects the resistance can exhibit T and V dependences that can be approximated\nby power laws. The corresponding two exponents differ greatly from each other\nand depend not only on the intrinsic electronic parameters but also on the\nimpurity distribution statistics."
    },
    {
        "anchor": "Quantum critical scaling in graphene: We show that the emergent relativistic symmetry of electrons in graphene near\nits quantum critical point (QCP) implies a crucial importance of the Coulomb\ninteraction. We derive scaling laws, valid near the QCP, that dictate the\nnontrivial magnetic and charge response of interacting graphene. Our analysis\nyields numerous predictions for how the Coulomb interaction will be manifested\nin experimental observables such as the diamagnetic response and electronic\ncompressibility.",
        "positive": "Some exact identities connecting one- and two-particle Green's functions\n  in spin-orbit coupling systems: Some exact identities connecting the one- and two-particle Green's functions\nin the presence of spin-orbit coupling have been derived. These identities is\nsimilar to the usual Ward identity in the particle or charge transport theory\nand a satisfying spin transport theory in spin-orbit coupling system should\nalso preserve these identities."
    },
    {
        "anchor": "Shot Noise in Disordered Junctions: Interaction Corrections: We study current correlation functions in a diffusive junction out of\nequilibrium. We calculate corrections to the electric current and to the zero\nfrequency shot noise due to electron-electron interactions. Contrary to the\nequilibrium situation (where the corrections to the current and to the current\nnoise are related through the fluctuation-dissipation theorem (FDT)), these two\nquantities behave differently: the correction to the electron current are\ngoverned by the largest of temperature and applied voltage, while the\ncorrection to the shot noise is always governed by the temperature. PACS Nos.\n71.10.Ay, 71.23.An, 73.50.Td",
        "positive": "Sum rule for transport in a Luttinger liquid with long range interaction\n  in the presence of an impurity: We show that the non-linear dc transport in a Luttinger liquid with\ninteraction of finite range in the presence of an impurity is governed by a sum\nrule which causes the charging energy to vanish."
    },
    {
        "anchor": "Casimir interaction of two dielectric half spaces with Chern-Simons\n  boundary layers: A diffraction problem for a flat Chern-Simons layer at plane boundary of a\ndielectric half space is solved. The Casimir energy of two dielectric half\nspaces with Chern-Simons layers at plane-parallel boundaries separated by a\nvacuum slit is derived. Crossing from the repulsive to the attractive Casimir\nforce is analyzed for two Au and two Si half spaces with boundary Chern-Simons\nlayers. Boundary quantum Hall layers in external magnetic field lead to Casimir\nrepulsion at nanoscales. We discuss features that make systems with boundary\nquantum Hall layers unique for force measurements and search of long-range\ninteractions beyond electromagnetism.",
        "positive": "Shot noise suppression in quasi one-dimensional Field Effect Transistors: We present a novel method for the evaluation of shot noise in quasi\none-dimensional field-effect transistors, such as those based on carbon\nnanotubes and silicon nanowires. The method is derived by using a statistical\napproach within the second quantization formalism and allows to include both\nthe effects of Pauli exclusion and Coulomb repulsion among charge carriers. In\nthis way it extends Landauer-Buttiker approach by explicitly including the\neffect of Coulomb repulsion on noise. We implement the method through the\nself-consistent solution of the 3D Poisson and transport equations within the\nNEGF framework and a Monte Carlo procedure for populating injected electron\nstates. We show that the combined effect of Pauli and Coulomb interactions\nreduces shot noise in strong inversion down to 23 % of the full shot noise for\na gate overdrive of 0.4 V, and that neglecting the effect of Coulomb repulsion\nwould lead to an overestimation of noise up to 180 %."
    },
    {
        "anchor": "Nitrogen-vacancy magnetometry of CrSBr by diamond membrane transfer: Magnetic imaging using nitrogen-vacancy (NV) spins in diamonds is a powerful\ntechnique for acquiring quantitative information about sub-micron scale\nmagnetic order. A major challenge for its application in the research on\ntwo-dimensional (2D) magnets is the positioning of the NV centers at a\nwell-defined, nanoscale distance to the target material required for detecting\nthe small magnetic fields generated by magnetic monolayers. Here, we develop a\ndiamond 'dry-transfer' technique, akin to the state-of-the-art 2D-materials\nassembly methods, and use it to place a diamond micro-membrane in direct\ncontact with the 2D interlayer antiferromagnet CrSBr. We harness the resulting\nNV-sample proximity to spatially resolve the magnetic stray fields generated by\nthe CrSBr, present only where the CrSBr thickness changes by an odd number of\nlayers. From the magnetic stray field of a single uncompensated ferromagnetic\nlayer in the CrSBr, we extract a monolayer magnetization of $M_\\mathrm{CSB}$ =\n0.46(2) T, without the need for exfoliation of monolayer crystals or applying\nlarge external magnetic fields. The ability to deterministically place\nNV-ensemble sensors into contact with target materials and detect ferromagnetic\nmonolayer magnetizations paves the way for quantitative analysis of a wide\nrange of 2D magnets assembled on arbitrary target substrates.",
        "positive": "Boundary Conditions for Electron Flow in Graphene in the Hydrodynamic\n  Regime: Graphene has generated a lot of research interest due to its special\nproperties, which include a hydrodynamic regime. It is not yet clear however\nwhich boundary condition such a hydrodynamic current flow satisfies. The aim of\nthis paper is to investigate the effect of different boundary conditions on the\npotential in an infinite strip of graphene, in which the electrons can be\ntreated hydrodynamically. The boundary conditions on the current range\ncontinuously from no-slip to a free boundary. We analyse the situation for two\ndifferent orientations of the source and sink, inspired by recent papers. We\ndiscuss which geometry is better suited for identifying the hydrodynamic regime\nand experimentally determining the boundary conditions."
    },
    {
        "anchor": "Aharonov-Bohm oscillations in bilayer graphene edge state Fabry-P\u00e9rot\n  interferometers: The charge and exchange statistics of an elementary excitation manifest in\nquantum coherent oscillations that can be explored in interferometry\nmeasurements. Quantum Hall interferometers are primary tools to uncover\nunconventional quantum statistics associated with fractional and non-Abelian\nanyons of a two-dimensional system, the latter being the foundation of\ntopological quantum computing. Graphene interferometers offer new avenues to\nexplore the physics of exotic excitations due to their relatively small\ncharging energies and sharp confinement potentials. Bilayer graphene possesses\na true band gap to facilitate the formation of quantum confinement and exhibits\nthe most robust even-denominator fractional quantum Hall states that may host\nnon-Abelian anyons. Here we present the design and fabrication of a split-gated\nbilayer graphene Fabry-P\\'erot interferometer and experimental evidence of\nAharonov-Bohm interference at multiple integer quantum Hall states. The\nversatility of the device allows us to study a wide range of scenarios,\ndetermine the velocities of edge states, and assess dephasing mechanisms of the\ninterferometer. These results pave the way to the quest of non-Abelian\nstatistics in this promising device platform.",
        "positive": "Nonequilibrium Green's functions and atom-surface dynamics: Simple views\n  from a simple model system: We employ Non-equilibrium Green's functions (NEGF) to describe the real-time\ndynamics of an adsorbate-surface model system exposed to ultrafast laser\npulses. For a finite number of electronic orbitals, the system is solved\nexactly and within different levels of approximation. Specifically i) the full\nexact quantum mechanical solution for electron and nuclear degrees of freedom\nis used to benchmark ii) the Ehrenfest approximation (EA) for the nuclei, with\nthe electron dynamics still treated exactly. Then, using the EA, electronic\ncorrelations are treated with NEGF within iii) 2nd Born and with iv) a recently\nintroduced hybrid scheme, which mixes 2nd Born self-energies with\nnon-perturbative, local exchange-correlation potentials of Density Functional\nTheory (DFT). Finally, the effect of a semi-infinite substrate is considered:\nwe observe that a macroscopic number of de-excitation channels can hinder\ndesorption. While very preliminary in character and based on a simple and\nrather specific model system, our results clearly illustrate the large\npotential of NEGF to investigate atomic desorption, and more generally, the non\nequilibrium dynamics of material surfaces subject to ultrafast laser fields."
    },
    {
        "anchor": "Probability distribution of the conductance at the mobility edge: Distribution of the conductance P(g) at the critical point of the\nmetal-insulator transition is presented for three and four dimensional\northogonal systems. The form of the distribution is discussed. Dimension\ndependence of P(g) is proven. The limiting cases $g\\to\\infty$ and $g\\to 0$ are\ndiscussed in detail and relation $P(g)\\to 0$ in the limit $g\\to 0$ is proven.",
        "positive": "Spin-dependent electron grating effect from helical magnetization in\n  multiferroic tunnel junctions: In multiferroic oxides with a transverse helical magnetic order, the\nmagnetization exchange coupling is sinusoidally space-dependent. We\ntheoretically investigate the spin-dependent electron grating effect in\nnormal-metal/helical-multiferroic/ferromagnettic heterojunctions. The spin wave\nvector of the spiral can be added or subtracted from the electron spacial wave\nvector inducing spin-conserved and spin-flipped diffracted transmission and\nreflection. The predicted grating effect can be controlled by magnetization\nexchange coupling strength, the helicity spatial period, and the magnetization\nof the ferromagnetic layer."
    },
    {
        "anchor": "Kosterlitz-Thouless transition in disordered two-dimensional topological\n  insulators: The disorder-driven metal-insulator transition in the quantum spin Hall\nsystems is studied by scaling analysis of the Thouless conductance $g$. Below a\ncritical disorder strength, the conductance is independent of the sample size\n$M$, an indication of critically delocalized electron states. The calculated\nbeta function $\\beta=d\\ln g/d\\ln M$ indicates that the metal-insulator\ntransition is Kosterlitz-Thouless (KT) type, which is characterized by bounding\nand unbounding of vortex-antivortex pairs of the local currents. The KT like\nmetal-insulator transition is a basic characteristic of the quantum spin Hall\nstate, being independent of the time-reversal symmetry.",
        "positive": "Nonlinear magneto-gyrotropic photogalvanic effect: We report on the observation of nonlinear magneto-gyrotropic photogalvanic\neffect in HgTe/HgCdTe quantum wells. The interband absorption of mid-infrared\nradiation as well as the intrasubband absorption of terahertz radiation in the\nheterostructures is shown to cause a dc electric current in the presence of an\nin-plane magnetic field. A cubic in magnetic field component of the\nphotocurrent is observed in quantum wells with the inverted band structure\nonly. The experimental data are discussed in terms of both the phenomenological\ntheory and microscopic models."
    },
    {
        "anchor": "Energy Barriers for Thermally Activated Magnetization Reversal in\n  Perpendicularly Magnetized Nanodisks in a Transverse Field: Thermally-induced transitions between bistable magnetic states of magnetic\ntunnel junctions (MTJ) are of interest for generating random bitstreams and for\napplications in stochastic computing. An applied field transverse to the easy\naxis of a perpendicularly magnetized MTJ (pMTJ) can lower the energy barrier\n($E_b$) to these transitions leading to faster fluctuations. In this study, we\npresent analytical and numerical calculations of $E_b$ considering both\ncoherent (macrospin) reversal and non-uniform wall-mediated magnetization\nreversal for a selection of nanodisk diameters and applied fields. Non-uniform\nreversal processes dominate for larger diameters, and our numerical\ncalculations of $E_b$ using the String method show that the transition state\nhas a sigmoidal magnetization profile. The latter can be described with an\nanalytical expression that depends on only one spatial dimension, parallel to\nthe applied field, which is also the preferred direction of profile motion\nduring reversal. Our results provide nanodisk energy barriers as a function of\nthe transverse field, nanodisk diameter, and material characteristics, which\nare useful for designing stochastic bitstreams.",
        "positive": "Stimulated Raman spin coherence and spin-flip induced hole burning in\n  charged GaAs quantum dots: High-resolution spectral hole burning (SHB) in coherent nondegenerate\ndifferential transmission spectroscopy discloses spin-trion dynamics in an\nensemble of negatively charged quantum dots. In the Voigt geometry, stimulated\nRaman spin coherence gives rise to Stokes and anti-Stokes sidebands on top of\nthe trion spectral hole. The prominent feature of an extremely narrow spike at\nzero detuning arises from spin population pulsation dynamics. These SHB\nfeatures confirm coherent electron spin dynamics in charged dots, and the\nlinewidths reveal spin spectral diffusion processes."
    },
    {
        "anchor": "Kondo effect in spin-orbit mesoscopic interferometers: We consider a flux-threaded Aharonov-Bohm ring with an embedded quantum dot\ncoupled to two normal leads. The local Rashba spin-orbit interaction acting on\nthe dot electrons leads to a spin-dependent phase factor in addition to the\nAharonov-Bohm phase caused by the external flux. Using the numerical\nrenormalization group method, we find a splitting of the Kondo resonance at the\nFermi level which can be compensated by an external magnetic field. To fully\nunderstand the nature of this compensation effect, we perform a scaling\nanalysis and derive an expression for the effective magnetic field. The\nanalysis is based on a tight-binding model which leads to an effective Anderson\nmodel with a spin-dependent density of states for the transformed lead states.\nWe find that the effective field originates from the combined effect of Rashba\ninteraction and magnetic flux and that it contains important corrections due to\nelectron-electron interactions. We show that the compensating field is an\noscillatory function of both the spin-orbit and the Aharonov-Bohm phases.\nMoreover, the effective field never vanishes due to the particle-hole symmetry\nbreaking independently of the gate voltage.",
        "positive": "Effect of magnetic field on fermions in graphene through\n  time-oscillating potential: We study the effect of a magnetic field on Dirac fermions in graphene subject\nto a scalar potential oscillating in time. Using the Floquet theory and\nresonance approximation, we show that the energy spectrum exhibits extra\nsubbands resulted from the oscillating potential in addition to quantized\nLandau levels. It is found that a current density can be generated in $ x $ and\n$ y $-directions that is strongly dependent on the magnetic field and\npotential. Our numerical analysis show that the energy spectrum possesses a\nsymmetry and the current density oscillates with different amplitudes under\nvarious conditions."
    },
    {
        "anchor": "Three-dimensional topological phases in a layered honeycomb spin-orbital\n  model: We present an exactly solvable spin-orbital model based on the Gamma-matrix\ngeneralization of a Kitaev-type Hamiltonian. In the presence of small magnetic\nfields, the model exhibits a critical phase with a spectrum characterized by\ntopologically protected Fermi points. Upon increasing the magnetic field, Fermi\npoints carrying opposite topological charges move toward each other and\nannihilate at a critical field, signaling a phase transition into a gapped\nphase with trivial topology in three dimensions. On the other hand, by\nsubjecting the system to a staggered magnetic field, an effective time-reversal\nsymmetry essential to the existence of three-dimensional topological insulators\nis restored in the auxiliary free fermion problem. The nontrivial topology of\nthe gapped ground state is characterized by an integer winding number and\nmanifests itself through the appearance of gapless Majorana fermions confined\nto the two-dimensional surface of a finite system.",
        "positive": "A transverse current rectification in graphene superlattice: A model for energy spectrum of superlattice on the base of graphene placed on\nthe striped dielectric substrate is proposed. A direct current component which\nappears in that structure perpendicularly to pulling electric field under the\ninfluence of elliptically polarized electromagnetic wave was derived. A\ntransverse current density dependence on pulling field magnitude and on\nmagnitude of component of elliptically polarized wave directed along the axis\nof a superlattice is analyzed."
    },
    {
        "anchor": "Radiative heat transfer between nanoparticles: shape dependence and\n  three-body effect: We study the effect of particles shape on the radiative heat transfer in a\nthree-body system. It is found that the radiative heat flux between two\nnanoparticles in a three body system can be tuned by the shape of the third\nparticle. In particular, we show that the heat flux is very sensitive to the\nparticle shapes and slight mismatches of shapes results in either enhanced or\nsuppressed heat flux.",
        "positive": "Simultaneous imaging of strain waves and induced magnetization dynamics\n  at the nanometer scale: Changes in strain can be used to modify electronic and magnetic properties in\ncrystal structures, to manipulate nanoparticles and cells, or to control\nchemical reactions. The magneto-elastic (ME) effect--the change of magnetic\nproperties caused by the elastic deformation (strain) of a magnetic\nmaterial--has been proposed as an alternative approach to magnetic fields for\nthe low power control of magnetization states of nanoelements since it avoids\ncharge currents, which entail ohmic losses. Multiferroic heterostructures\n\\cite{Zheng2004} and nanocomposites have exploited this effect in search of\nelectric control of magnetic states, mostly in the static regime. Quantitative\nstudies combining strain and magnetization dynamics are needed for practical\napplications and so far, a high resolution technique for this has been lacking.\nHere, we have studied the effect of the dynamic strain accompanying a surface\nacoustic wave on magnetic nanostructures. We have simultaneously imaged the\ntemporal evolution of both strain waves and magnetization dynamics of\nnanostructures at the picosecond timescale. The newly developed experimental\ntechnique, based on X-ray microscopy, is versatile and provides a pathway to\nthe study of strain-induced effects at the nanoscale. Our results provide\nfundamental insight in the coupling between strain and magnetization in\nnanostructures at the picosecond timescale, having implications in the design\nof strain-controlled magnetostrictive nano-devices."
    },
    {
        "anchor": "Generation of pure bulk valley current in graphene: The generation of valley current is a fundamental goal in graphene\nvalleytronics but no practical ways of its realization are known yet. We\npropose a workable scheme for the generation of bulk valley current in a\ngraphene mechanical resonator through adiabatic cyclic deformations of the\nstrains and chemical potential in the suspended region. The accompanied strain\ngauge fields can break the spatial mirror symmetry of the problem within each\nof the two inequivalent valleys, leading to a fnite valley current due to\nquantum pumping. An all-electrical measurement configuration is designed to\ndetect the novel state with pure bulk valley currents.",
        "positive": "Magnetic susceptibility of crystals with crossing of their band-contact\n  lines: We theoretically study the orbital magnetic susceptibility produced by\nelectron states near a crossing point of two band-contact lines in a crystal.\nIt is shown that this susceptibility can have an unusual dependence on the\nFermi level and can change noticeably with the temperature when the Fermi level\nis in the vicinity of the crossing point. These features of the magnetic\nsusceptibility can be useful in detecting the crossing points in crystal. The\nobtained results explain the well-known temperature dependence of the magnetic\nsusceptibility of V$_3$Si."
    },
    {
        "anchor": "Velocity renormalization and anomalous quasiparticle dispersion in\n  extrinsic graphene: Using many-body diagrammatic perturbation theory we consider carrier density-\nand substrate-dependent many-body renormalization of doped or gated graphene\ninduced by Coulombic electron-electron interaction effects. We quantitatively\ncalculate the many-body spectral function, the renormalized quasiparticle\nenergy dispersion, and the renormalized graphene velocity using the\nleading-order self-energy in the dynamically screened Coulomb interaction\nwithin the ring diagram approximation. We predict experimentally detectable\nmany-body signatures, which are enhanced as the carrier density and the\nsubstrate dielectric constant are reduced, finding an intriguing instability in\nthe graphene excitation spectrum at low wave vectors where interaction\ncompletely destroys all particle-like features of the noninteracting linear\ndispersion. We also make experimentally relevant quantitative predictions about\nthe carrier density and wave-vector dependence of graphene velocity\nrenormalization induced by electron-electron interaction. We compare on-shell\nand off-shell self-energy approximations within the ring diagram approximation,\nfinding a substantial quantitative difference between their predicted velocity\nrenormalization corrections in spite of the generally weak-coupling nature of\ninteraction in graphene.",
        "positive": "Spin-torque switching in large size nano-magnet with perpendicular\n  magnetic fields: DC current induced magnetization reversal and magnetization oscillation was\nobserved in 500 nm large size Co90Fe10/Cu/Ni80Fe20 pillars. A perpendicular\nexternal field enhanced the coercive field separation between the reference\nlayer (Co90Fe10) and free layer (Ni80Fe20) in the pseudo spin valve, allowing a\nlarge window of external magnetic field for exploring the free-layer reversal.\nThe magnetization precession was manifested in terms of the multiple peaks on\nthe differential resistance curves. Depending on the bias current and applied\nfield, the regions of magnetic switching and magnetization precession on a\ndynamical stability diagram has been discussed in details. Micromagnetic\nsimulations are shown to be in good agreement with experimental results and\nprovide insight for synchronization of inhomogenieties in large sized device.\nThe ability to manipulate spin-dynamics on large size devices could prove\nuseful for increasing the output power of the spin-transfer nano-oscillators\n(STNOs)."
    },
    {
        "anchor": "Einstein--de Haas fluctuation of a nanoparticle in spin polarized gases: We theoretically study angular momentum (AM) transfer from a spin-polarized\ndilute gas into an nanoparitcle (NP) tightly trapped in optical tweezers. We\nformulate a microscopic model based on the spin tunneling Hamiltonian method\nand derive a macroscopic stochastic differential equation (SDE) which governs\nthe AM-transfer-induced rotational motion of the NP. It is shown that the AM\ntransfer rate at the NP surface can be extracted via the inference of the SDE.\nThis work will open the door to the manipulation of nano-spintronic systems in\ngaseous environments.",
        "positive": "Double-Fano resonance in a two-level quantum system coupled to zigzag\n  Phosphorene nanoribbon: Double-level quantum systems are good candidates for revealing coherent\nquantum transport properties. Here, we consider quantum interference effects\ndue to the formation of a two-level system (TLS) coupled to the edge channel of\na zigzag Phosphorene nanoribbon (ZPNR). Using the tight-binding approach, we\nfirst demonstrate the formation of a TLS in bulk Phosphorene sheet due to the\nexistence of two nearby vacancy impurities. Then, we show that such a TLS can\ncouple to the quasi-one-dimensional continuum of the edge states in a ZPNR\nwhich results in the the appearance of two-dip Fano-type line shapes. To this\nend, we generalize the Lippmann-Schwinger approach to study the scattering of\nedge electrons in a ZPNR by two coupled impurity defects. We obtain an\nanalytical expression of the transmission coefficient which shows that the\npositions and widths of the anti-resonances can be controlled by changing the\nintervacancy distance as well as their distance from the edge of the ribbon.\nThis work constitutes a clear example of the multiple Fano resonances in\nmesoscopic transport."
    },
    {
        "anchor": "Thermopower of crown-ether-bridged anthraquinones: We investigate strategies for increasing the thermopower of\ncrown-ether-bridged anthraquinones. The novel design feature of these molecules\nis the presence of either (1) crown-ether or (2) diaza-crown-ether bridges\nattached to the side of the current-carrying anthraquinone wire. The\ncrown-ether side groups selectively bind alkali- metal cations and when\ncombined with TCNE or TTF dopants, provide a large phase-space for optimising\nthermoelectric properties. We find that the optimum combination of cations and\ndopants depends on the temperature range of interest. The thermopowers of both\n1 and 2 are negative and at room temperature are optimised by binding with TTF\nalone, achieving thermpowers of -600 microvolts/K and -285 microvolts/K\nrespectively. At much lower temperatures, which are relevant to cascade\ncoolers, we find that for 1, a combination of TTF and Na+ yields a maximum\nthermopower of -710 microvolts/K at 70K, whereas a combination of TTF and Li+\nyields a maximum thermopower of -600 microvolts/K at 90K. For 2, we find that\nTTF doping yields a maximum thermopower of -800 microvolts/K at 90K, whereas at\n50K, the largest thermopower (of -600 microvolts/K) is obtain by a combination\nTTF and K+ doping. At room temperature, we obtain power factors of 73\nmicrowatts/m.K2 for 1 (in combination with TTF and Na+ ) and 90 microwatts/m.K2\nfor 2 (with TTF). These are higher or comparable with reported power factors of\nother organic materials.",
        "positive": "Magnetochiral anisotropy-induced nonlinear planar Hall effect in\n  Topological Insulator surface states: In an intriguing recent experiment, it has been found that the\ntwo-dimensional (2D) surface states of a three-dimensional (3D) strong\ntopological insulator (TI) support a non-zero Hall voltage transverse to an\napplied electric field even when the external magnetic field is in the plane\n(i.e., the in-plane Lorentz force vanishes). This so-called planar Hall effect\n(PHE) of TI surface states is found to be non-linear, i.e., the Hall voltage\nscales quadratically with the applied electric field and linearly with the\nin-plane magnetic field. In this paper, we derive the non-linear PHE for strong\ntopological insulator surface states and show that the derivations contained in\nthe previous literature are incomplete, which can lead to quantitative or even\nin some cases qualitative errors in the estimates for the nonlinear planar Hall\nresistance. We derive the complete expressions for the non-linear planar Hall\ncurrents for TI surface states with broken particle-hole symmetry and provide\nresults for different regimes of the surface state Hamiltonian which can be\ncompared with future experiments."
    },
    {
        "anchor": "Phase-engineering the Andreev band structure of a three-terminal\n  Josephson junction: In hybrid Josephson junctions with three or more superconducting terminals\ncoupled to a semiconducting region, Andreev bound states may form\nunconventional energy band structures, or Andreev matter, which are engineered\nby controlling superconducting phase differences. Here we report tunnelling\nspectroscopy measurements of three-terminal Josephson junctions realised in an\nInAs/Al heterostructure. The three terminals are connected to form two loops,\nenabling independent control over two phase differences and access to a\nsynthetic Andreev band structure in the two-dimensional phase space. Our\nresults demonstrate a phase-controlled Andreev molecule, originating from two\ndiscrete Andreev levels that spatially overlap and hybridise. Signatures of\nhybridisation are observed in the form of avoided crossings in the spectrum and\nband structure anisotropies in the phase space, all explained by a numerical\nmodel. Future extensions of this work could focus on addressing spin-resolved\nenergy levels, ground state fermion parity transitions and Weyl bands in\nmultiterminal geometries.",
        "positive": "Emission of coherent THz magnons in an antiferromagnetic insulator\n  triggered by ultrafast spin-phonon interactions: Antiferromagnetic materials have been proposed as new types of narrowband THz\nspintronic devices owing to their ultrafast spin dynamics. Manipulating\ncoherently their spin dynamics, however, remains a key challenge that is\nenvisioned to be accomplished by spin-orbit torques or direct optical\nexcitations. Here, we demonstrate the combined generation of broadband THz\n(incoherent) magnons and narrowband (coherent) magnons at 1 THz in low damping\nthin films of NiO/Pt. We evidence, experimentally and through modelling, two\nexcitation processes of magnetization dynamics in NiO, an off-resonant\ninstantaneous optical spin torque and a strain-wave-induced THz torque induced\nby ultrafast Pt excitation. Both phenomena lead to the emission of a THz signal\nthrough the inverse spin Hall effect in the adjacent heavy metal layer. We\nunravel the characteristic timescales of the two excitation processes found to\nbe < 50 fs and > 300 fs, respectively, and thus open new routes towards the\ndevelopment of fast opto-spintronic devices based on antiferromagnetic\nmaterials."
    },
    {
        "anchor": "Wigner localization in a graphene quantum dot with a mass gap: In spite of unscreened Coulomb interactions close to charge neutrality,\nrelativistic massless electrons in graphene allegedly behave as noninteracting\nparticles. A clue to this paradox is that both interaction and kinetic energies\nscale with particle density in the same way. In contrast, in a dilute gas of\nnonrelativistic electrons the different scaling drives the transition to Wigner\ncrystal. Here we show that Dirac electrons in a graphene quantum dot with a\nmass gap localize \\`a la Wigner for realistic values of device parameters. Our\ntheoretical evidence relies on many-body observables obtained through the exact\ndiagonalization of the interacting Hamiltonian, which allows us to take all\nelectron correlations into account. We predict that the experimental signatures\nof Wigner localization are the suppression of the fourfold periodicity of the\nfilling sequence and the quenching of excitation energies, which may be both\naccessed through Coulomb blockade spectroscopy. Our findings are relevant to\nother carbon-based nanostructures exhibiting a mass gap.",
        "positive": "Strain-induced spin resonance shifts in silicon devices: In spin-based quantum information processing devices, the presence of control\nand detection circuitry can change the local environment of a spin by\nintroducing strain and electric fields, altering its resonant frequencies.\nThese resonance shifts can be large compared to intrinsic spin line-widths and\nit is therefore important to study, understand and model such effects in order\nto better predict device performance. Here we investigate a sample of bismuth\ndonor spins implanted in a silicon chip, on top of which a superconducting\naluminium micro-resonator has been fabricated. The on-chip resonator provides\ntwo functions: first, it produces local strain in the silicon due to the larger\nthermal contraction of the aluminium, and second, it enables sensitive electron\nspin resonance spectroscopy of donors close to the surface that experience this\nstrain. Through finite-element strain simulations we are able to reconstruct\nkey features of our experiments, including the electron spin resonance spectra.\nOur results are consistent with a recently discovered mechanism for producing\nshifts of the hyperfine interaction for donors in silicon, which is linear with\nthe hydrostatic component of an applied strain."
    },
    {
        "anchor": "Graphene with wedge disclination in the presence of intrinsic and Rashba\n  spin orbit couplings: In this article, the modified Kane-Mele Hamiltonian is derived for graphene\nwith wedge disclination and spin orbit couplings (intrinsic and Rashba). The\nwedge disclination changes the flat lattice into the conical lattice and hence\nmodifies the spin orbit couplings. The Hamiltonian is exactly solved for the\nintrinsic spin orbit interaction and perturbatively for the Rashba spin orbit\ninteraction. It is shown that there exists the Kramer's degenerate midgap\nlocalized spin separated fluxon states around the defect. These zero energy\nspin separated states occur at the external magnetic flux value\n$\\Phi\\pm\\Delta\\Phi$. The external magnetic flux $\\Phi$ is introduced to make\nthe wave-function periodic when the electron circulates around the defect. It\nis found that this separation occurs due to the effect of the conical curvature\non the spin orbit coupling. Further, we find these results are robust to the\naddition of the Rashba spin orbit interaction which is important for the\napplication to spintronics and nanoelectronics.",
        "positive": "Multi-spin errors in the optical control of a spin quantum memory: We study a quantum memory composed of an array of charged quantum dots\nembedded in a planar cavity. Optically excited polaritons, i.e. exciton-cavity\nmixed states, interact with the electron spins in the dots. Linearly polarized\nexcitation induces two-spin and multi-spin interactions. We discuss how the\nmulti-spin interaction terms, which represent a source of errors for two-qubit\nquantum gates, can be suppressed using local control of the exciton energy. We\nshow that using detuning conditional phase shift gates with high fidelity can\nbe obtained. The cavity provides long-range spin coupling and the resulting\ngate operation time is shorter than the spin decoherence time."
    },
    {
        "anchor": "Edge electron states for quasi-one-dimensional organic conductors in the\n  magnetic-field-induced spin-density-wave phases: We develop a microscopic picture of the electron states localized at the\nedges perpendicular to the chains in the Bechgaard salts in the quantum Hall\nregime. In a magnetic-field-induced spin-density-wave state (FISDW)\ncharacterized by an integer N, there exist N branches of chiral gapless edge\nexcitations. Localization length is much longer and velocity much lower for\nthese states than for the edge states parallel to the chains. We calculate the\ncontribution of these states to the specific heat and propose a time-of-flight\nexperiment to probe the propagating edge modes directly.",
        "positive": "Tunable thermopower in a graphene-based topological insulator: Following the recent proposal by Weeks et al., which suggested that indium\n(or thallium) adatoms deposited on the surface of graphene should turn the\nlatter into a quantum spin Hall (QSH) insulator characterized by a sizeable\ngap, we perform a systematic study of the transport properties of this system\nas a function of the density of randomly distributed adatoms. While the samples\nare, by construction, very disordered, we find that they exhibit an extremely\nstable QSH phase with no signature of the spatial inhomogeneities of the adatom\nconfiguration. We find that a simple rescaling of the spin-orbit coupling\nparameter allows us to account for the behaviour of the inhomogeneous system\nusing a homogeneous model. This robustness opens the route to a much easier\nexperimental realization of this topological insulator. We additionally find\nthis material to be a very promising candidate for thermopower generation with\na target temperature tunable from 1 to 80K and an efficiency ZT close to 1."
    },
    {
        "anchor": "Quantum oscillations without magnetic field: When magnetic field $B$ is applied to a metal, nearly all observable\nquantities exhibit oscillations periodic in $1/B$. Such quantum oscillations\nreflect the fundamental reorganization of electron states into Landau levels as\na canonical response of the metal to the applied magnetic field. We predict\nhere that, remarkably, in the recently discovered Dirac and Weyl semimetals\nquantum oscillations can occur in the complete absence of magnetic field. These\nzero-field quantum oscillations are driven by elastic strain which, in the\nspace of the low-energy Dirac fermions, acts as a chiral gauge potential. We\npropose an experimental setup in which the strain in a thin film (or nanowire)\ncan generate pseudomagnetic field $b$ as large as 15T and demonstrate the\nresulting de Haas-van Alphen and Shubnikov-de Haas oscillations periodic in\n$1/b$.",
        "positive": "Orientation of the Stripe Formed by the Two-Dimensional Electrons in\n  Higher Landau Levels: Effect of periodic potential on the stripe phase realized in the higher\nLandau levels is investigated by the Hartree-Fock approximation. The period of\nthe potential is chosen to be two to six times of the fundamental period of the\nstripe phase. It is found that the stripe aligns perpendicularly to the\nexternal potential in contrast to a naive expectation and hydrodynamic theory.\nCharge modulation towards the Wigner crystallization along the stripe is\nessential for the present unexpected new result."
    },
    {
        "anchor": "Fingerprints of Qubit Noise in Transient Cavity Transmission: Noise affects the coherence of qubits and thereby places a bound on the\nperformance of quantum computers. We theoretically study a generic two-level\nsystem with fluctuating control parameters in a photonic cavity and find that\nbasic features of the noise spectral density are imprinted in the transient\ntransmission through the cavity. We obtain analytical expressions for generic\nnoise and proceed to study the cases of quasistatic, white and $1/f^{\\alpha}$\nnoise in more detail. Additionally, we propose a way of extracting the spectral\ndensity for arbitrary noise in a frequency band only bounded by the range of\nthe qubit-cavity detuning and with an exponentially decaying error due to\nfinite measurement times. Our results suggest that measurements of the\ntime-dependent transmission probability represent a novel way of extracting\nnoise characteristics.",
        "positive": "Modulation effect on the spin Hall resonance: The effect of a weak electrical modulation on spin Hall resonance is\npresented here. In presence of the magnetic field normal to the plane of the\nmotion of electron, the Landau levels are formed which get broadened due to the\nweak modulation. The width of the Landau levels broadening are periodic with\nthe inverse magnetic field. There is a certain magnetic field for which the\ncrossing of Landau levels between spin-up and spin-down branches takes place.\nThis gives rise to the resonance in the spin Hall conductivity (SHC). The\nLandau levels broadening or the energy correction due to the modulation removes\nthe singularity appears at the resonance field in SHC, leading to the\nsuppression of SHC accompanied by two new peaks around this point. The\nseparation of these two peaks increases with the increase of the modulation\nperiod. Moreover, we find that the height of the two peaks are also modulation\nperiod dependent."
    },
    {
        "anchor": "3D Hopping Conduction in SnO2 nanobelts: The temperature dependence of the electrical transport of a individual tin\noxide nanobelt was measured, in darkness, from 400 to 5K. We found four\nintrinsic electrical transport mechanisms through the nanobelt. It starts with\nThermal-Activation Conduction between 400 and 314K, Nearest-Neighbor Hopping\nconduction between 268 and 115K, and Variable Range Hopping conduction below\n58K, with a crossover from the 3D-Mott to the 3D-Efros-Shklovskii regime at\n16K. We claim that this sequence reveal the three-dimensional nature of the\nelectrical transport in the SnO2 nanobelts, even they are expected to behave as\none-dimensional systems.",
        "positive": "Fano-Andreev effect in T-shape double-quantum-dot in the Kondo regime: In the present work, we investigate the electronic transport through a\nT-shape double quantum dot system coupled to two normal leads and to one\nsuperconducting lead. We explore the interplay between Kondo and Andreev states\ndue to proximity effects. We find that Kondo resonance is modified by the\nAndreev bound states, which manifest through Fano antiresonances in the local\ndensity of states of the embedded quantum dot and normal transmission. This\nmeans that there is a correlation between Andreev bound states and Fano\nresonances that is robust under the influence of high electronic correlation.\nWe have also found that the dominant couplings at the quantum dots are\ncharacterized by a crossover region that defines the range where the Fano-Kondo\nand the Andreev-Kondo effect prevail in each quantum dot. Likewise, we find\nthat the interaction between Kondo and Andreev bound states has a notable\ninfluence on the Andreev transport."
    },
    {
        "anchor": "Optimal efficiency and power and their trade-off in three-terminal\n  quantum thermoelectric engines with two output electric currents: We establish a theory of optimal efficiency and power for three-terminal\nthermoelectric engines which have two independent output electric currents and\none input heat current. This set-up goes beyond the conventional heat engines\nwith only one output electric current. For such a set-up, we derive the optimal\nefficiency and power and their trade-off for three-terminal heat engines with\nand without time-reversal symmetry. The formalism goes beyond the known optimal\nefficiency and power for systems with or without time-reversal symmetry,\nshowing interesting features that have not been revealed before. A concrete\nexample of quantum-dot heat engine is studied to show that the current set-up\ncan have much improved efficiency and power compared with previous set-ups with\nonly one output electric current. Our analytical results also apply for\nthermoelectric heat engines with multiple output electric currents, providing\nan alternative scheme toward future high-performance thermoelectric materials.",
        "positive": "Geometric control of universal hydrodynamic flow in a two dimensional\n  electron fluid: Fluid dynamics is one of the cornerstones of modern physics and has recently\nfound applications in the transport of electrons in solids. In most solids\nelectron transport is dominated by extrinsic factors, such as sample geometry\nand scattering from impurities. However in the hydrodynamic regime Coulomb\ninteractions transform the electron motion from independent particles to the\ncollective motion of a viscous `electron fluid'. The fluid viscosity is an\nintrinsic property of the electron system, determined solely by the\nelectron-electron interactions. Resolving the universal intrinsic viscosity is\nchallenging, as it only affects the resistance through interactions with the\nsample boundaries, whose roughness is not only unknown but also varies from\ndevice to device. Here we eliminate all unknown parameters by fabricating\nsamples with smooth sidewalls to achieve the perfect slip boundary condition,\nwhich has been elusive both in molecular fluids and electronic systems. We\nengineer the device geometry to create viscous dissipation and reveal the true\nintrinsic hydrodynamic properties of a 2D system. We observe a clear transition\nfrom ballistic to hydrodynamic electron motion, driven by both temperature and\nmagnetic field. We directly measure the viscosity and electron-electron\nscattering lifetime (the Fermi quasiparticle lifetime) over a wide temperature\nrange without fitting parameters, and show they have a strong dependence on\nelectron density that cannot be explained by conventional theories based on the\nRandom Phase Approximation."
    },
    {
        "anchor": "Comment on \"Physical Origin and Generic Control of Magnonic Band Gaps of\n  Dipole-Exchange Spin Waves in Width-Modulated Nanostrip Waveguides\" [K.-S.\n  Lee, D.-S. Han, and S.-K. Kim, PRL 102, 127202 (2009), arXiv:0811.0411]: In Ref. [PRL 102, 127202 (2009)] Lee et al. reported the existence of large\nmagnonic bandgaps in one-dimensional width-modulated Permalloy nanostripe\nwaveguides based on OOMMF simulations. However, as the symmetry of the magnetic\nfield pulse they applied to excite the spin waves (SWs) was not general, the\nentire set of SW branches with A symmetry was omitted from the magnonic band\nstructures (see below). This omission has unfortunately led to misleading\nconclusions of, for instance, the number, width and position of the bandgaps.\nWe present here the full band structure based on three different theoretical\napproaches that gave consistent predictions, thus corroborating the methods\nemployed, namely, a microscopic approach, OOMMF simulations, and a method based\non the linearized Landau-Lifshitz equation. Further, we provide a physical\ninterpretation using group theory.",
        "positive": "Quantum-dot single-electron transistor as thermoelectric quantum\n  detectors at terahertz frequencies: Low dimensional nano-systems are promising candidates for manipulating,\ncontrolling and capturing photons with large sensitivities and low-noise. If\nquantum engineered to tailor the energy of the localized electrons across the\ndesired frequency range, they can allow devising efficient quantum sensors\nacross any frequency domain. Here, we exploit the rich few-electrons physics to\ndevelop millimeter-wave nanodetectors employing as sensing element an\nInAs/InAs0.3P0.7 quantum-dot nanowire, embedded in a single electron\ntransistor. Once irradiated with light the deeply localized quantum element\nexhibits an extra electromotive force driven by the photothermoelectric effect,\nwhich is exploited to efficiently sense radiation at 0.6 THz with a noise\nequivalent power < 8 pWHz-1/2 and almost zero dark current. The achieved\nresults open intriguing perspectives for quantum key distributions, quantum\ncommunications and quantum cryptography at terahertz frequencies."
    },
    {
        "anchor": "Spin-selective transmission through a single-stranded magnetic helix: Magnetic helix (MH) structure can be a role model for future spintronic\ndevices. Utilizing the advantage of constructing possible magnetic\nconfigurations, in the present work first time we investigate spintronic\nbehavior, to the best of our knowledge, in a helical geometry with finite\nmagnetic ordering. The interplay between short-range and long-range hopping of\nelectrons yields many non-trivial features which are thoroughly studied. Quite\ninterestingly we see that the MH exhibits the strong chiral-induced spin\nselectivity effect, like what is observed in chiral molecules. Finally, to make\nthe model more realistic we also examine the effect of helical dynamics. All\nthe results are valid for a wide range of physical parameters, which prove the\nrobustness of our analysis.",
        "positive": "The Hartree-Fock state for the 2DEG at filling factor 1/2 revisited:\n  analytic solution, dynamics and correlation energy: The CDW Hartree-Fock state at half filling and half electron per unit cell is\nexamined. Firstly, an exact solution in terms of Bloch-like states is\npresented. Using this solution we discuss the dynamics near half filling and\nshow the mass to diverge logarithmically as this filling is approached. We also\nshow how a uniform density state may be constructed from a linear combination\nof two degenerate solutions. Finally we show the second order correction to the\nenergy to be an order of magnitude larger than that for competing CDW solutions\nwith one electron per unit cell."
    },
    {
        "anchor": "Interaction of Magnetization and Heat Dynamics for Pulsed Domain Wall\n  Movement with Joule Heating: Pulsed domain wall movement is studied here in Ni80Fe20 nanowires on SiO2,\nusing a fully integrated electrostatic, thermoelectric, and micromagnetics\nsolver based on the Landau-Lifshitz-Bloch equation, including Joule heating,\nanisotropic magneto-resistance, and Oersted field contributions. During the\napplied pulse the anisotropic magneto-resistance of the domain wall generates a\ndynamic heat gradient which increases the current-driven velocity by up to 15%.\nUsing a temperature-dependent conductivity significant differences are found\nbetween the constant voltage-pulsed and constant current-pulsed domain wall\nmovement: constant voltage pulses are shown to be more efficient at displacing\ndomain walls whilst minimizing the increase in temperature, with the total\ndomain wall displacement achieved over a fixed pulse duration having a maximum\nwith respect to the driving pulse strength.",
        "positive": "Dynamics of a two-level system coupled with a quantum oscillator in the\n  very strong coupling limit: The time-dependent behavior of a two-level system interacting with a quantum\noscillator system is analyzed in the case of a coupling larger than both the\nenergy separation between the two levels and the energy of quantum oscillator\n($\\Omega < \\omega < \\lambda $, where $\\Omega $ is the frequency of the\ntransition between the two levels, $\\omega $ is the frequency of the\noscillator, and $\\lambda $ is the coupling between the two-level system and the\noscillator). Our calculations show that the amplitude of the expectation value\nof the oscillator coordinate decreases as the two-level system undergoes the\ntransition from one level to the other, while the transfer probability between\nthe levels is staircase-like. This behavior is explained by the interplay\nbetween the adiabatic and the non-adiabatic regimes encountered during the\ndynamics with the system acting as a quantum counterpart of the Landau-Zener\nmodel. The transition between the two levels occurs as long as the expectation\nvalue of the oscillator coordinate is driven close to zero. On the contrary, if\nthe initial conditions are set such that the expectation values of the\noscillator coordinate are far from zero, the system will remain locked on one\nlevel."
    },
    {
        "anchor": "Vortices in spinor cold exciton condensates with spin-orbit interaction: We study theoretically the ground states of topological defects in a spinor\nfour-component condensate of cold indirect excitons. We analyze possible ground\nstate solutions for different configurations of vortices and half-vortices. We\nshow that if only Rashba or Dreselhaus spin-orbit interaction (SOI) for\nelectrons is present the stable states of topological defects can represent a\ncylindrically symmetric half-vortex or half vortex-antivortex pairs, or a\nnon-trivial pattern with warped vortices. In the presence of both of Rashba and\nDresselhaus SOI the ground state of a condensate represents a stripe phase and\nvortex type solutions become unstable.",
        "positive": "Temperature-dependent spectral properties of (GaIn)As/Ga(AsSb)/(GaIn)As\n  W-quantum well heterostructure lasers: This paper discusses the temperature-dependent properties of\n(GaIn)As/Ga(AsSb)/(GaIn)As W-quantum well heterostructures for laser\napplications based on theoretical modeling as well as experimental findings. A\nmicroscopic theory is applied to discuss band bending effects giving rise to\nthe characteristic blue shift with increasing charge carrier density observed\nin type-II heterostructures. Furthermore, gain spectra for a W-quantum well\nheterostructure are calculated up to high charge carrier densities. At these\nhigh charge carrier densities, the interplay between multiple type-II\ntransitions results in broad and flat gain spectra with a spectral width of\napproximately 160 nm. Furthermore, the temperature-dependent properties of\nbroad-area edge-emitting lasers are analyzed using electroluminescence as well\nas laser characteristic measurements. A first indication for the theoretically\npredicted broad gain spectra is presented and the interplay between the\ntemperature-dependent red shift and the charge carrier density-dependent blue\nshift is discussed. A combination of these effects results in a significant\nreduction of the temperature-induced red shift of the emission wavelengths and\neven negative shift rates of (-0.10 plusminus 0.04) nm/K are achieved."
    },
    {
        "anchor": "Shot Noise by Quantum Scattering in Chaotic Cavities: We have experimentally studied shot noise of chaotic cavities defined by two\nquantum point contacts in series. The cavity noise is determined as 1/4*2e|I|\nin agreement with theory and can be well distinguished from other contributions\nto noise generated at the contacts. Subsequently, we have found that cavity\nnoise decreases if one of the contacts is further opened and reaches nearly\nzero for a highly asymmetric cavity.",
        "positive": "Quantum signal transmission through a single-qubit chain: A system of a two-level atom of an impurity (qubit) inserted into a periodic\nchain coupled to the continuum is studied with the use of the effective\nnon-Hermitian Hamiltonian. Exact solutions are derived for the quasistationary\neigenstates, their complex energies, and transport properties. Due to the\npresence of the qubit, two long-lived states corresponding to the ground and\nexcited states of the qubit emerge outside the Bloch energy band. These states\nremain essentially localized at the qubit even in the limit of sufficiently\nstrong coupling between the chain and the environment when the super-radiant\nstates are formed. The transmission through the chain is studied as a function\nof the continuum coupling strength and the chain-qubit coupling; the perfect\nresonance transmission takes place through isolated resonances at weak and\nstrong continuum coupling, while the transmission is lowered in the\nintermediate regime."
    },
    {
        "anchor": "Current-induced macrospin vs spin-wave excitations in spin valves: The mode dependence of current-induced magnetic excitations in spin valves is\nstudied theoretically. The torque exerted on the magnetization by transverse\nspin currents as well as the Gilbert damping constant are found to depend\nstrongly on the wave length of the excitation (spin wave). Analytic expressions\nare presented for the critical currents that excite a selected spin wave. The\nonset of macrospin (zero wavelength) vs finite wavelength instabilities depends\non the device parameters and the current direction, in agreement with recent\nexperimental findings.",
        "positive": "Interacting fermions in 1D disordered lattices: Exploring localization\n  and transport properties with lattice density-functional theories: We investigate the static and dynamical behavior of 1D interacting fermions\nin disordered Hubbard chains, contacted to semi-infinite leads. The chains are\ndescribed via the repulsive Anderson-Hubbard Hamiltonian, using static and\ntime-dependent lattice density-functional theory. The dynamical behavior of our\nquantum transport system is performed via an integration scheme available in\nthe literature, which we modify via the recursive Lanczos method, to increase\nits efficiency. To quantify the degree of localization due to disorder and\ninteractions, we adapt the definition of the inverse participation ratio to\nobtain an indicator which is both suitable for quantum transport geometries and\nwhich can be obtained within density-functional theory. Lattice density\nfunctional theories are reviewed and, for contacted chains, we analyze the\nmerits and limits of the coherent-potential approximation in describing the\nspectral properties, with interactions included via lattice density functional\ntheory. Our approach appears to able to capture complex features due to the\ncompetition between disorder and interactions. Specifically, we find a\ndynamical enhancement of delocalization in presence of a finite bias, and an\nincrease of the steady-state current induced by inter-particle interactions.\nThis behavior is corroborated by results for the time-dependent densities and\nfor the inverse participation ratio. Using short isolated chains with\ninteraction and disorder, a brief comparative analysis between time-dependent\ndensity-functional theory and exact results is then given, followed by general\nconclusive remarks."
    },
    {
        "anchor": "Spin Hall Effect and Origins of Nonlocal Resistance in Adatom-Decorated\n  Graphene: Recent experiments reporting unexpectedly large spin Hall effect (SHE) in\ngraphene decorated with adatoms have raised a fierce controversy. We apply\nnumerically exact Kubo and Landauer- B\u007futtiker formulas to realistic models of\ngold-decorated disordered graphene (including adatom clustering) to obtain the\nspin Hall conductivity and spin Hall angle, as well as the nonlocal resistance\nas a quantity accessible to experiments. Large spin Hall angles of 0.1 are\nobtained at zero-temperature, but their dependence on adatom clustering differs\nfrom the predictions of semiclassical transport theories. Furthermore, we find\nmultiple background contributions to the nonlocal resistance, some of which are\nunrelated to SHE or any other spin-dependent origin, as well as a strong\nsuppression of SHE at room temperature. This motivates us to design a\nmultiterminal graphene geometry which suppresses these background contributions\nand could, therefore, quantify the upper limit for spin current generation in\ntwo-dimensional materials.",
        "positive": "Bloch's theory in periodic structures with Rashba's spin-orbit\n  interaction: We consider a two-dimensional electron gas with Rashba's spin-orbit\ninteraction and two in-plane potentials superimposed along directions\nperpendicular to each other. The first of these potentials is assumed to be a\ngeneral periodic potential while the second one is totally arbitrary. A general\nform for Bloch's amplitude is found and an eigen-value problem for the band\nstructure of the system is derived. We apply the general result to the two\nparticular cases in which either the second potential represents a harmonic\nin-plane confinement or it is zero. We find that for a harmonic confinement\nregions of the Brillouin zone with high polarizations are associated with the\nones of large group velocity."
    },
    {
        "anchor": "Metal-insulator transition in vanadium dioxide nanobeams: probing\n  sub-domain properties of strongly correlated materials: Many strongly correlated electronic materials, including high-temperature\nsuperconductors, colossal magnetoresistance and metal-insulator-transition\n(MIT) materials, are inhomogeneous on a microscopic scale as a result of domain\nstructure or compositional variations. An important potential advantage of\nnanoscale samples is that they exhibit the homogeneous properties, which can\ndiffer greatly from those of the bulk. We demonstrate this principle using\nvanadium dioxide, which has domain structure associated with its dramatic MIT\nat 68 degrees C. Our studies of single-domain vanadium dioxide nanobeams reveal\nnew aspects of this famous MIT, including supercooling of the metallic phase by\n50 degrees C; an activation energy in the insulating phase consistent with the\noptical gap; and a connection between the transition and the equilibrium\ncarrier density in the insulating phase. Our devices also provide a\nnanomechanical method of determining the transition temperature, enable\nmeasurements on individual metal-insulator interphase walls, and allow general\ninvestigations of a phase transition in quasi-one-dimensional geometry.",
        "positive": "Artificial out-of-plane Ising antiferromagnet on the kagome lattice with\n  very small further neighbour couplings: Despite their simple formulation, short range classical antiferromagnetic\nIsing models on frustrated lattices give rise to exotic phases of matter, in\nparticular due to their macroscopic ground state degeneracy. Recent experiments\non artificial spin systems comprising arrays of chirally coupled nanomagnets\nprovide a significant strengthening of the nearest neighbour couplings compared\nto systems with dipolar-coupled nanomagnets. This opens the way to design\nartificial spin systems emulating Ising models with nearest neighbour\ncouplings. In this paper, we compare the results of an extensive investigation\nwith tensor network and Monte Carlo simulations of the nearest- and\nfurther-neighbour ($J_1-J_2-J_{3||}$) kagome Ising antiferromagnet with the\nexperimental spin-spin correlations of a kagome lattice of chirally coupled\nnanomagnets. Even though the ratios between the further neighbour couplings and\nthe nearest neighbour coupling estimated from micromagnetic simulations are\nmuch smaller than for dipolar-coupled nanomagnets, we show that they still play\nan essential role in the selection of the correlations."
    },
    {
        "anchor": "A high-sensitivity charge sensor for silicon qubits above one kelvin: Recent studies of silicon spin qubits at temperatures above 1 K are\nencouraging demonstrations that the cooling requirements for solid-state\nquantum computing can be considerably relaxed. However, qubit readout\nmechanisms that rely on charge sensing with a single-island single-electron\ntransistor (SISET) quickly lose sensitivity due to thermal broadening of the\nelectron distribution in the reservoirs. Here we exploit the tunneling between\ntwo quantised states in a double-island SET (DISET) to demonstrate a charge\nsensor with an improvement in signal-to-noise by an order of magnitude compared\nto a standard SISET, and a single-shot charge readout fidelity above 99 % up to\n8 K at a bandwidth > 100 kHz. These improvements are consistent with our\ntheoretical modelling of the temperature-dependent current transport for both\ntypes of SETs. With minor additional hardware overheads, these sensors can be\nintegrated into existing qubit architectures for high fidelity charge readout\nat few-kelvin temperatures.",
        "positive": "Single-Molecule Junction Conductance through Diaminoacenes: The study of electron transport through single molecules is essential to the\ndevelopment of molecular electronics. Indeed, trends in electronic conductance\nthrough organic nanowires have emerged with the increasing reliability of\nelectron transport measurements at the single-molecule level. Experimental and\ntheoretical work has shown that tunneling distance, HOMO-LUMO gap and molecular\nconformation influence electron transport in both saturated and pi-conjugated\nnanowires. However, there is relatively little experimental data on electron\ntransport through fused aromatic rings. Here we show using diaminoacenes that\nconductivity depends not only on the number of fused aromatic rings in the\nmolecule, which defines the molecular HOMO-LUMO gap, but also on the position\nof the amino groups on the rings. Specifically, we find that conductance is\nhighest with minimal disruption of aromaticity in fused aromatic nanowires."
    },
    {
        "anchor": "Magnetization transport and quantized spin conductance: We analyze transport of magnetization in insulating systems described by a\nspin Hamiltonian. The magnetization current through a quasi one-dimensional\nmagnetic wire of finite length suspended between two bulk magnets is determined\nby the spin conductance which remains finite in the ballistic limit due to\ncontact resistance. For ferromagnetic systems, magnetization transport can be\nviewed as transmission of magnons and the spin conductance depends on the\ntemperature T. For antiferromagnetic isotropic spin-1/2 chains, the spin\nconductance is quantized in units of order $(g \\mu_B)^2/h$ at T=0.\nMagnetization currents produce an electric field and hence can be measured\ndirectly. For magnetization transport in electric fields phenomena analogous to\nthe Hall effect emerge.",
        "positive": "Nonlinear drift-diffusion model of gating in the fast Cl channel: The dynamics of the open or closed state region of an ion channel may be\ndescribed by a probability density $p(x,t)$ which satisfies a Fokker-Planck\nequation. The closed state dwell-time distribution $f_c(t)$ derived from the\nFokker-Planck equation with a nonlinear diffusion coefficient $D(x) \\propto\n\\exp(-\\gamma x)$, $\\gamma > 0$ and a linear ramp potential $U_c(x)$, is in good\nagreement with experimental data and it may be shown analytically that if\n$\\gamma$ is sufficiently large, $f_c(t) \\propto t^{-2 - \\nu}$ for intermediate\ntimes, where $\\nu = U_c^{\\prime}/\\gamma \\approx -0.3$ for a fast Cl channel.\nThe solution of a master equation which approximates the Fokker-Planck equation\nexhibits an oscillation superimposed on the power law trend and can account for\nan empirical rate-amplitude correlation that applies to several ion channels."
    },
    {
        "anchor": "Spin Textures of Polariton Condensates in a Tunable Microcavity with\n  Strong Spin-Orbit Interaction: We report an extended family of spin textures in coexisting modes of\nzero-dimensional polariton condensates spatially confined in tunable open\nmicrocavity structures. The coupling between photon spin and angular momentum,\nwhich is enhanced in the open cavity structures, leads to new eigenstates of\nthe polariton condensates carrying quantised spin vortices. Depending on the\nstrength and anisotropy of the cavity confinement potential and the strength of\nthe spin-orbit coupling, which can be tuned via the excitonic/photonic\nfractions, the condensate emissions exhibit either spin-vortex-like patterns or\nlinear polarization, in good agreement with theoretical modelling.",
        "positive": "Conductance oscillations induced by ballistic snake states in a graphene\n  heterojunction: The realization of p-n junctions in graphene, combined with the gapless and\nchiral nature of its massless Dirac fermions has led to the observation of many\nintriguing phenomena such as quantum Hall effect in bipolar regime, Klein\ntunneling, and Fabry-P\\'{e}rot interferences all of which involve electronic\ntransport across p-n junctions. Ballistic snake states propagating along the\np-n junctions have been predicted to induce conductance oscillations,\nmanifesting their twisting nature. However, transport studies along p-n\njunctions have so far only been performed in low mobility devices. Here, we\nreport the observation of conductance oscillations due to ballistic snake\nstates along a p-n interface in high quality graphene encapsulated by hexagonal\nboron nitride. These snake states are exceptionally robust as they can\npropagate over $12$~$\\mu$m, limited only by the size of our sample, and survive\nup to at least $120$~K. The ability to guide carriers over a long distance\nprovide a crucial building block for graphene-based electron optics."
    },
    {
        "anchor": "Strong-field-driven dynamics and high-harmonic generation in interacting\n  1D systems: We explore the roles of electronic band structure and Coulomb interactions in\nsolid-state HHG by studying the optical response of linear atomic chains and\ncarbon nanotubes to intense ultrashort pulses. Specifically, we simulate\nelectron dynamics by solving the single-particle density matrix equation of\nmotion in the presence of intense ultrafast optical fields, incorporating\ntight-binding electronic states and a self-consistent electron-electron\ninteraction. While linear atomic chains constitute an idealized system, our\nrealistic 1D model readily provides insight on the temporal evolution of\nelectronic states in reciprocal space, both in the absence or presence of\nelectron interactions, which we demonstrate to play an important role in the\nHHG yield. This model further predicts that doped semiconductors generate high\nharmonics more efficiently than their metallic and undoped counterparts. To\ncomplement this idealized system we also show results for HHG in more realistic\nquasi-1D structures such as carbon nanotubes, the behavior of which is found to\nbe in good qualitative agreement with the atomic chains. Our findings apply\ndirectly to extreme nonlinear optical phenomena in atoms on surfaces,\ncarbon-based structures, linear arrays of dopant atoms in semiconductors, and\nlinear molecules, such as polycyclic aromatic hydrocarbon chains, and can be\nstraightforwardly extended to optimize existing platforms for HHG or identify\nnew solid-state alternatives in the context of nonlinear plasmonics.",
        "positive": "Localization of a magnetic moment using a two-qubit probe: A nanomagnet precessing in an external magnetic field can be treated as a\nsource of narrow-bandwidth magnetic noise, that leaves characteristic\nfingerprints in decoherence of a nearby spin qubit undergoing dynamical\ndecoupling. We show how, by measurements of two-qubit coherence, a noise sensor\ncomposed of qubit pair can be used to reconstruct the position of the\nnanomagnet. Such localization of noise source is possible with only two qubit\nprobes, because the course of coherence decay under appropriately designed\ndynamical decoupling sequences contain information not only about noises\nexperienced by each qubit, but also about their cross-correlations. We test the\napplicability of the proposed protocol on an example of two qubits coupled to\nthe nanomagnet via dipolar interaction. We also show how, using a two-qubit\nsensor possessing a particular symmetry, one can localize the nanomagnet even\nwhen the sensor-magnet coupling law is unknown."
    },
    {
        "anchor": "Persistent Enhancement of Exciton Diffusivity in CsPbBr3 Nanocrystal\n  Solids: In semiconductors, exciton or charge carrier diffusivity is typically\ndescribed as an inherent material property. Here, we show that the transport of\nexcitons (i.e., bound electron-hole pairs) in CsPbBr3 perovskite nanocrystals\n(NCs) depends markedly on how recently those NCs were occupied by a previous\nexciton. Using fluence- and repetition-rate-dependent transient\nphotoluminescence microscopy, we visualize the effect of excitation frequency\non exciton transport in CsPbBr3 NC solids. Surprisingly, we observe a striking\ndependence of the apparent exciton diffusivity on excitation laser power that\ndoes not arise from nonlinear exciton-exciton interactions nor from thermal\nheating of the sample. We interpret our observations with a model in which\nexcitons cause NCs to undergo a transition to a metastable configuration that\nadmits faster exciton transport by roughly an order of magnitude. This\nmetastable configuration persists for ~microseconds at room temperature, and\ndoes not depend on the identity of surface ligands or presence of an oxide\nshell, suggesting that it is an intrinsic response of the perovskite lattice to\nelectronic excitation. The exciton diffusivity observed here (>0.15 cm2/s) is\nconsiderably higher than that observed in other NC systems on similar\ntimescales, revealing unusually strong excitonic coupling in a NC material. The\nfinding of a persistent enhancement in excitonic coupling between NCs may help\nexplain other extraordinary photophysical behaviors observed in CsPbBr3 NC\narrays, such as superfluorescence. Additionally, faster exciton diffusivity\nunder higher photoexcitation intensity is likely to provide practical insights\nfor optoelectronic device engineering.",
        "positive": "Landau-quantized excitonic absorption and luminescence in a monolayer\n  valley semiconductor: We investigate Landau-quantized excitonic absorption and luminescence of\nmonolayer WSe$_2$ under magnetic field. We observe gate-dependent quantum\noscillations in the bright exciton and trions (or exciton-polarons) as well as\nthe dark trions and their phonon replicas. Our results reveal spin- and\nvalley-polarized Landau levels (LLs) with filling factors $n = +0, +1$ in the\nbottom conduction band and $n = -0$ to $-6$ in the top valence band, including\nthe Berry-curvature-induced $n = \\pm0$ LLs of massive Dirac fermions. The LL\nfilling produces periodic plateaus in the exciton energy shift accompanied by\nsharp oscillations in the exciton absorption width and magnitude. This peculiar\nexciton behavior can be simulated by semi-empirical calculations. The\nexperimentally deduced g-factors of the conduction band (g ~ 2.5) and valence\nband (g ~ 15) exceed those predicted in a single-particle model (g = 1.5, 5.5,\nrespectively). Such g-factor enhancement implies strong many-body interactions\nin gated monolayer WSe$_2$. The complex interplay between Landau quantization,\nexcitonic effects, and many-body interactions makes monolayer WSe$_2$ a\npromising platform to explore novel correlated quantum phenomena."
    },
    {
        "anchor": "Probabilistic teleportation of a quantum dot spin qubit: Electron spin s in semiconductor quantum dot s have been intensively studied\nfor implementing quantum computation and high fidelity single and two qubit\noperation s have recently been achieved . Quantum teleportation is a three\nqubit protocol exploiting quantum entanglement and it serv es as a n essential\nprimitive for more sophisticated quantum algorithm s Here, we demonstrate a\nscheme for quantum teleportation based on direct Bell measurement for a single\nelectron spin qubit in a triple quantum dot utilizing the Pauli exclusion\nprinciple to create and detect maximally entangled state s . T he single spin\npolarization is teleported from the input qubit to the output qubit with a\nfidelity of 0.9 1 We find this fidelity is primarily limited by singlet triplet\nmixing which can be improved by optimizing the device parameters Our results\nmay be extended to quantum algorithms with a larger number of se miconductor\nspin qubit s",
        "positive": "Direct current generation due to wave mixing in zigzag carbon nanotubes: Generation of direct current in zigzag carbon nanotubes due to harmonic\nmixing of two coherent electromagnetic waves is being considered. The\nelectromagnetic waves have commensurate frequencies of omega and two omega. The\nrectification of the waves at high frequencies is quite smooth whiles at low\nfrequencies there are some fluctuations. The nonohmicity observed in the\nI-Vcharacteristics is attributed to the nonparabolicity of the electron energy\nband which is very strong in carbon nanotubes because of high stark component.\nIt is observed that the current falls off faster at lower electric field than\nthe case in superlattice. For omega tau equal to two? the external electric\nfield strength Emax for the observation of negative differential conductivity\noccurs around 1.03x10e6 V/m which is quite weak. It is interesting to note that\nthe peak of the curve shifts to the left with increasing value of omega tau?"
    },
    {
        "anchor": "Non-linear ballistic response of quantum spin-Hall edge states: Topological edge states exhibit dissipationless transport and\nelectrically-driven topological phase transitions, making them ideal for\nnext-generation transistors that are not constrained by Moore's law.\nNevertheless, their dispersion has never been probed and is often assumed to be\nsimply linear, without any rigorous justification. Here we determine the\nnon-linear electrical response of topological edge states in the ballistic\nregime and demonstrate the way this response ascertains the presence of\nsymmetry breaking terms in the edge dispersion, such as deviations from\nnon-linearity and tilted spin quantization axes. The non-linear response stems\nfrom discontinuities in the band occupation on either side of a Zeeman gap, and\nits direction is set by the spin orientation with respect to the Zeeman field.\nWe determine the edge dispersion for several classes of topological materials\nand discuss experimental measurement.",
        "positive": "Adiabatic transport in nanostructures: A confined system of non-interacting electrons, subject to the combined\neffect of a time-dependent potential and different external\nchemical-potentials, is considered. The current flowing through such a system\nis obtained for arbitrary strengths of the modulating potential, using the\nadiabatic approximation in an iterative manner. A new formula is derived for\nthe charge pumped through an un-biased system (all external chemical potentials\nare kept at the same value); It reproduces the Brouwer formula for a\ntwo-terminal nanostructure. The formalism presented yields the effect of the\nchemical potential bias on the pumped charge on one hand, and the modification\nof the Landauer formula (which gives the current in response to a constant\nchemical-potential difference) brought about by the modulating potential on the\nother. Corrections to the adiabatic approximation are derived and discussed."
    },
    {
        "anchor": "A multiscale and multiphysics framework to simulate radiation damage in\n  nano-crystalline materials: This work presents a multiscale and multiphysics framework to investigate the\nradiation-induced damage in nano-crystalline materials. The framework combines\ntwo methodologies, including molecular dynamics simulations with electronic\neffects and long-term atomistic diffusion simulations in nano-crystalline\nmaterials. Using this framework, we investigated nano-crystalline materials'\nself-healing behavior under radiation events. We found that the number of\ndefects generated in nano-crystals during the cascade simulations was less than\nin single crystals. This behavior was due to the fast absorption of\ninterstitial atoms in the grain boundary network during the cascade\nsimulations, while vacancies migrated to the boundaries in a much longer time\nscale than interstitial atoms. Thus, nano-crystalline materials showed a\nself-healing behavior where the number and size of the defects are drastically\nreduced with time. We found that the self-healing behavior of nano-crystalline\nmaterials is limited, and about 50% of vacancies survived. This effect resulted\nfrom clusters of vacancies' collective behavior, which are much more stable\nthan individual vacancies.",
        "positive": "Bulk-boundary quantum oscillations in inhomogeneous Weyl semimetals: Weyl fermions in an external magnetic field exhibit the chiral anomaly, a\nnon-conservation of chiral fermions. In a Weyl semimetal, a spatially\ninhomogeneous Weyl node separation causes similar effect by creating an\nintrinsic pseudo-magnetic field with an opposite sign for nodes of opposite\nchirality. In the present work we study the interplay of external and intrinsic\nfields. In particular, we focus on quantum oscillations due to bulk-boundary\ntrajectories. When caused by an external field, such oscillations are a proven\nexperimental technique to detect Weyl semimetals. We show that the intrinsic\nfield leaves hallmarks on such oscillations by decreasing the period of the\noscillations in an analytically traceable manner. The oscillations can thus be\nused to test the effect of an intrinsic field and to extract its strength."
    },
    {
        "anchor": "Quality Atomic Resolution Scanning Tunneling Microscope Imaging up to 27\n  T in Water-cooled Magnet: We report the achievement of the first atomically resolved scanning tunneling\nmicroscope (STM) imaging in a water-cooled magnet (WM), where the extremely\nharsh vibrations and noises have been the major challenge. This homebuilt\nWM-STM features an ultra-rigid and compact scan head in which the coarse\napproach is driven by our new design of the TunaDrive piezoelectric motor. A\nthree-level spring hanging system is exploited for vibration isolation.\nRoom-temperature raw-data images of graphite with quality atomic resolution\nwere obtained in very high magnetic fields up to 27 T in a 32 mm bore WM whose\nabsolute maximum field is 27.5 T at the power rating of 10 MW. This record of\n27 T has exceeded the maximum field strength of the conventional\nsuperconducting magnets. Besides, our WM-STM has also paved the way to the STM\nimaging in the 45 T, 32 mm bore hybrid magnet, which is the world's flagship\nmagnet and can produces the highest steady magnetic field at present.",
        "positive": "Magneto shot noise in noncollinear diffusive spin-valves: We develop a semiclassical Boltzmann-Langevin theory of the spin polarized\nshot noise in a diffusive normal metal spin-valve connected by tunnel contacts\nto ferromagnetic reservoirs with noncollinear magnetizations. We obtain basic\nequations for correlations of the fluctuating spin-charge distribution and\ncurrent density matrices by taking into account the spin-flip processes and\nprecession of the spin accumulation vector in the normal metal. Applying the\ndeveloped theory to a two terminal FNF structure, we find that for a small\nspin-flip strength and a substantial polarization of the terminals the shot\nnoise has a nonmonotonic variation with the angle between magnetization\nvectors. While the shot noise is almost unchanged from the normal structure\nvalue for parallel configuration and increases well above the normal value for\nantiparallel configuration, it suppresses substantially at an intermediate\nangle depending on the ratio of the conductances of the N metal and the tunnel\ncontacts. We also demonstrated pronounced effects of the polarization and the\nspin-flip scattering on the shot noise which reveals the interplay between\nrelaxation and precession of the spin accumulation vector in the N metal."
    },
    {
        "anchor": "Many-body spectrum and particle localization in quantum dots and finite\n  rotating Bose condensates: The yrast spectra (i.e. the lowest states for a given total angular momentum)\nof quantum dots in strong magnetic fields, are studied in terms of exact\nnumerical diagonalization and analytic trial wave functions. We argue that\ncertain features (cusps) in the many-body spectrum can be understood in terms\nof particle localization due to the strong field. A new class of trial\nwavefunctions supports the picture of the electrons being localized in Wigner\nmolecule-like states consisting of consecutive rings of electrons, with\nlow-lying excitations corresponding to rigid rotation of the outer ring of\nelectrons. The geometry of the Wigner molecule is independent of interparticle\ninteractions and the statistics of the particles.",
        "positive": "Reversal of magnetization of a single-domain magnetic particle by the ac\n  field of time-dependent frequency: We report numerical and analytical studies of the reversal of the magnetic\nmoment of a single-domain magnetic particle by a circularly polarized ac field\nof time-dependent frequency. For the time-linear frequency sweep, the phase\ndiagrams are computed that illustrate the dependence of the reversal on the\nfrequency sweep rate v, the amplitude of the ac field h, the magnetic\nanisotropy field d, and the damping parameter alpha. It is shown that the most\nefficient magnetization reversal requires a non-linear time dependence of the\nfrequency, omega(t), for which an exact analytical formula is derived with\naccount of damping. The necessary condition of the reversal is h > alpha d.\nImplementation of a small-scale magnetization reversal is proposed in which a\nnanomagnet is electromagnetically coupled to two weak superconducting links\ncontrolled by the voltage. Dynamics of such a system is analyzed with account\nof the back effect of the magnet on the superconducting links."
    },
    {
        "anchor": "Dynamical Corrections to Spin Wave Excitations in Quantum Wells due to\n  Coulomb Interactions and Magnetic Ions: We have measured dispersions of spin-flip waves and spin-flip single-particle\nexcitations of a spin polarized two-dimensional electron gas in a CdMnTe\nquantum well using resonant Raman scattering. We find the energy of the\nspin-flip wave to be below the spin-flip single particle excitation continuum,\na contradiction to the theory of spin waves in diluted magnetic semiconductors\nput forth in [Phys. Rev. B 70, 045205 (2004)]. We show that the inclusion of\nterms accounting for the Coulomb interaction between carriers in the spin wave\npropagator leads to an agreement with our experimental results. The dominant\nCoulomb contribution leads to an overall red shift of the mixed electron-Mn\nspin modes while the dynamical coupling between Mn ions results in a small blue\nshift. We provide a simulated model system which shows the reverse situation\nbut at an extremely large magnetic field.",
        "positive": "The magnetic susceptibility of disordered non-diffusive mesoscopic\n  systems: Disorder-induced spectral correlations of mesoscopic quantum systems in the\nnon-diffusive regime and their effect on the magnetic susceptibility are\nstudied. We perform impurity averaging for non-translational invariant systems\nby combining a diagrammatic perturbative approach with semiclassical\ntechniques. This allows us to study the entire range from clean to diffusive\nsystems. As an application we consider the magnetic response of non-interacting\nelectrons in microstructures in the presence of weak disorder. We show that in\nthe ballistic case (elastic mean free path $\\ell$ larger than the system size)\nthere exist two distinct regimes of behaviour depending on the relative\nmagnitudes of $\\ell$ and an inelastic scattering length $L_{\\phi}$. We present\nnumerical results for square billiards and derive approximate analytical\nresults for generic chaotic geometries. The magnetic field dependence and\n$L_{\\phi}$ dependence of the disorder-induced susceptibility is qualitatively\nsimilar in both types of geometry."
    },
    {
        "anchor": "Enhancing single-parameter quantum charge pumping in carbon-based\n  devices: We present a theoretical study of quantum charge pumping with a single ac\ngate applied to graphene nanoribbons and carbon nanotubes operating with low\nresistance contacts. By combining Floquet theory with Green's function\nformalism, we show that the pumped current can be tuned and enhanced by up to\ntwo orders of magnitude by an appropriate choice of device length, gate voltage\nintensity and driving frequency and amplitude. These results offer a promising\nalternative for enhancing the pumped currents in these carbon-based devices.",
        "positive": "Hysteretic phenomena in a 2DEG in quantum Hall effect regime studied in\n  a transport experiment: We investigated experimentally non-equilibrium state of a two-dimensional\nelectron gas (2DEG) in the quantum Hall effect (QHE) regime, studying the\nhysteresis of magnetoresistance of a 2DEG with a constriction. The large\namplitude of the hysteresis enabled us to make the consistent phenomenological\ndescription of the hysteresis. We studied the dependence on the magnetic field\nsweep prehistory (minor loop measurements), recovered the anhysteretic curve,\nand studied the time dependence of the magnetoresistance. We showed that the\nhysteresis of magnetoresistance of a 2DEG in the QHE regime has significant\nphenomenological similarities with the hysteresis of magnetization of\nferromagnetic materials, showing multistability, jumps of relaxation, and\nhaving the anhysteretic curve. Nevertheless, we revealed the crucial\ndifference, manifested itself in an unusual inverted (anti-coercive) behavior\nof the magnetoresistance hysteresis. The time relaxation of the hysteresis has\nfast and slow regimes, similar to that of non-equilibrium magnetization of a\n2DEG in QHE regime pointing to their common origin. We studied the dependence\nof the hysteresis loop area on the lithographic width of the constriction and\nfound the threshold value of width $\\sim$1.35 $\\mu$m beyond which the\nhysteresis is not observed. This points to the edge nature of the\nnon-equilibrium currents (NECs) and allows us to determine the width of the\nNECs area ($\\sim$0.5 $\\mu$m). We suggest the qualitative picture of the\nobserved hysteresis, based on non-equilibrium redistribution of the electrons\namong the Landau level states and assuming huge imbalance between the\npopulation of bulk and edge electronic states."
    },
    {
        "anchor": "Cyclotron-resonance-assisted photon drag effect in InSb/InAlSb quantum\n  wells excited by terahertz radiation: We report on the observation of the cyclotron-resonance-assisted photon drag\neffect. Resonant photocurrent is detected in InSb/InAlSb quantum wells\nstructures subjected to a static magnetic field and excited by terahertz\nradiation at oblique incidence. The developed theory based on Boltzmann's\nkinetic equation is in a good agreement with the experimental findings. We show\nthat the resonant photocurrent originates from the transfer of photon momentum\nto free electrons drastically enhanced at cyclotron resonance.",
        "positive": "Optical Absorption in Twisted Bilayer Graphene: We theoretically study the optical absorption property of twisted bilayer\ngraphenes with various stacking geometries, and demonstrate that the\nspectroscopic characteristics serve as a fingerprint to identify the rotation\nangle between two layers. We find that the absorption spectrum almost\ncontinuously evolves in changing the rotation angle, regardless of the lattice\ncommensurability. The spectrum is characterized by series of peaks associated\nwith the van Hove singularity, and the peak energies systematically shift with\nthe rotation angle. We calculate the optical absorption in two different\nframeworks; the tight-binding model and the effective continuum model based on\nthe Dirac equation. For small rotation angles less than $10^\\circ$, the\neffective model well reproduces the low-energy band structure and the optical\nconductivity of the tight-binding model, and also explains the optical\nselection rule analytically in terms of the symmetry of the effective\nHamiltonian."
    },
    {
        "anchor": "Anomalous Stability of nu=1 Bilayer Quantum Hall State: We have studied the fractional and integer quantum Hall (QH) effects in a\nhigh-mobility double-layer two-dimensional electron system. We have compared\nthe \"stability\" of the QH state in balanced and unbalanced double quantum\nwells. The behavior of the n=1 QH state is found to be strikingly different\nfrom all others. It is anomalously stable, though all other states decay, as\nthe electron density is made unbalanced between the two quantum wells. We\ninterpret the peculiar features of the nu=1 state as the consequences of the\ninterlayer quantum coherence developed spontaneously on the basis of the\ncomposite-boson picture.",
        "positive": "Catalytic Growth of N-doped MgO on Mo(001): A simple pathway to grow thin films of N-doped MgO (MgO:N), which has been\nfound experimentally to be a ferromagnetic d0 insulator, is presented. It\nrelies on the catalytic properties of a Mo(001) substrate using growth of Mg in\na mixed atmosphere of O2 and N2. Scanning tunneling spectroscopy reveals that\nthe films are insulating and exhibit an N-induced state slightly below the\nconduction band minimum."
    },
    {
        "anchor": "Tuning Rashba spin-orbit coupling at LaAlO3/SrTiO3 interfaces by band\n  filling: The electric-field tunable Rashba spin-orbit coupling at the LaAlO3/SrTiO3\ninterface shows potential applications in spintronic devices. However,\ndifferent gate dependence of the coupling strength has been reported in\nexperiments. On the theoretical side, it has been predicted that the largest\nRashba effect appears at the crossing point of the $d_{xy}$ and $d_{xz,yz}$\nbands. In this work, we study the tuneability of the Rashba effect in\nLaAlO3/SrTiO3 by means of back-gating. The Lifshitz transition was crossed\nmultiple times by tuning the gate voltage so that the Fermi energy is tuned to\napproach or depart from the band crossing. By analyzing the weak\nantilocalization behavior in the magnetoresistance, we find that the maximum\nspin-orbit coupling effect occurs when the Fermi energy is near the Lifshitz\npoint. Moreover, we find strong evidence for a single spin winding at the Fermi\nsurface.",
        "positive": "Interaction corrections to the thermopower of the disordered\n  two-dimensional electron gas: At low temperatures, the transport coefficients in the disordered electron\ngas acquire quantum corrections as a result of the complex interplay of\ndisorder and interactions. The interaction corrections to the electric\nconductivity have their origin in virtual processes with typical electronic\nenergies far exceeding the temperature. Here, we study interaction corrections\n$\\delta S$ to the thermopower $S$ of the two-dimensional disordered electron\ngas with long-range Coulomb interactions. We show that while both real and\nvirtual processes contribute to these corrections, the real processes are\ndominant and lead to a logarithmic temperature dependence of $\\delta S/S$ with\n$\\delta S/S<0$."
    },
    {
        "anchor": "Gate control, g-factors and spin orbit energy of p-type GaSb nanowire\n  quantum dot devices: Proposals for quantum information applications are frequently based on the\ncoherent manipulation of spins confined to quantum dots. For these\napplications, p-type III-V material systems promise a reduction of the\nhyperfine interaction while maintaining large $g$-factors and strong spin-orbit\ninteraction. In this work, we study bottom-gated device architectures to\nrealize single and serial multi-quantum dot systems in Schottky contacted\np-type GaSb nanowires. We find that the effect of potentials applied to gate\nelectrodes on the nanowire is highly localized to the immediate vicinity of the\ngate electrode only, which prevents the formation of double quantum dots with\ncommonly used device architectures. We further study the transport properties\nof a single quantum dot induced by bottom-gating, find large gate-voltage\ndependent variations of the $g^*$-factors up to $8.1\\pm 0.2$ as well as\nspin-orbit energies between $110$-$230\\,\\mu$eV.",
        "positive": "Dirac Fermions in Solids - from High Tc cuprates and Graphene to\n  Topological Insulators and Weyl Semimetals: Understanding Dirac-like Fermions has become an imperative in modern\ncondensed matter sciences: all across its research frontier, from graphene to\nhigh T$_c$ superconductors to the topological insulators and beyond, various\nelectronic systems exhibit properties which can be well described by the Dirac\nequation. Such physics is no longer the exclusive domain of quantum field\ntheories and other esoteric mathematical musings; instead, real physics of real\nsystems is governed by such equations, and important materials science and\npractical implications hinge on our understanding of Dirac particles in two and\nthree dimensions. While the physics that gives rise to the massless Dirac\nFermions in each of the above mentioned materials is different, the low energy\nproperties are governed by the same Dirac kinematics. The aim of this article\nis to review a selected cross-section of this vast field by highlighting the\ngeneralities, and contrasting the specifics, of several physical systems."
    },
    {
        "anchor": "On geometric delusions of hexagonal structures: The confining geometries of fermions in 2D structures exhibits interesting\nresults that have highest symmetry. Delusion can be considered as the\ntopological effect which is topological invariant. Topologically, genus zero\nsurfaces needs excess of pentagons while in surfaces g>2 surfaces needs excess\nof heptagons. The curvature effect and the rise of effective gauge field can be\ninterpreted from delusion effects in hexagonal lattice. This idea is novel in\nits scope as it can state theoretical description of structures and their\nstability.",
        "positive": "Reply to a Comment on ``Nonequilibrium Electron Distribution in Presence\n  of Kondo Impurities'' (cond-mat/0105026): Claims by Kroha and Zawadowski in cond-mat/0105026 on inadequate\napproximations and an incorrect statement in cond-mat/0102150 are shown to be\nbased on oversimplified estimates and a false quotation."
    },
    {
        "anchor": "Solvable 4-state Landau-Zener model of two interacting qubits with path\n  interference: We identify a nontrivial 4-state Landau-Zener model for which transition\nprobabilities between any pair of diabatic states can be determined\nanalytically and exactly. The model describes an experimentally accessible\nsystem of two interacting qubits, such as a localized state in a Dirac material\nwith both valley and spin degrees of freedom or a singly charged quantum dot\n(QD) molecule with spin orbit coupling. Application of the linearly\ntime-dependent magnetic field induces a sequence of quantum level crossings\nwith possibility of interference of different trajectories in a semiclassical\npicture. We argue that this system satisfies the criteria of integrability in\nthe multistate Landau-Zener theory, which allows us to derive explicit exact\nanalytical expressions for the transition probability matrix. We also argue\nthat this model is likely a special case of a larger class of solvable systems,\nand present a 6-state generalization as an example.",
        "positive": "All-optical flow control of a polariton condensate using non-resonant\n  excitation: The precise adjustment of the polariton condensate flow under incoherent\nexcitation conditions is an indispensable prerequisite for polariton-based\nlogic gate operations. In this report, an all-optical approach for steering the\nmotion of a polariton condensate using only non-resonant excitation is\ndemonstrated. We create arbitrarily shaped functional potentials by means of a\nspatial light modulator, which allow for tailoring the condensate state and\nguiding a propagating condensate along reconfigurable pathways. Additional\nnumerical simulations confirm the experimental observations and elucidate the\ninteraction effects between background carriers and polariton condensates."
    },
    {
        "anchor": "Experimental demonstration of the topological surface states protected\n  by the time-reversal symmetry: We report direct imaging of standing waves of the nontrivial surface states\nof topological insulator Bi$_2$Te$_3$ by using a low temperature scanning\ntunneling microscope. The interference fringes are caused by the scattering of\nthe topological states off Ag impurities and step edges on the\nBi$_2$Te$_3$(111) surface. By studying the voltage-dependent standing wave\npatterns, we determine the energy dispersion $E(k)$, which confirms the Dirac\ncone structure of the topological states. We further show that, very different\nfrom the conventional surface states, the backscattering of the topological\nstates by nonmagnetic impurities is completely suppressed. The absence of\nbackscattering is a spectacular manifestation of the time-reversal symmetry,\nwhich offers a direct proof of the topological nature of the surface states.",
        "positive": "Lifshitz-like argument for low-lying states in a strong magnetic field: We propose a Lifshitz argument in order to analyse the low energy spectrum of\nan electron moving in a strong magnetic field and scattered by randomly\ndistributed repulsive zero-range impurities. The typical configurations of\ndisorder which give rise to low energy states are identified as clusters of\nimpurities. This allows for an interpretation of low-lying states localized\naround these clusters."
    },
    {
        "anchor": "On the Lorenz number of multi-band materials: There are many exotic scenarios where the Lorenz number of the\nWiedemann-Franz law is known to deviate from expected values. However, in\nconventional semiconductor systems, it is assumed to vary between the values of\n~1.49x10^{-8} W {\\Omega} K^{-2} for non-degenerate semiconductors and\n~2.45x10^{-8} W {\\Omega} K^{-2} for degenerate semiconductors or metals.\nKnowledge of the Lorenz number is important in many situations, such as in the\ndesign of thermoelectric materials and in the experimental determination of the\nlattice thermal conductivity. Here we show that, even in the simple case of two\nand three band semiconductors, it is possible to obtain substantial deviations\nof a factor of two (or in the case of a bipolar system with a Fermi level near\nthe midgap, even orders of magnitude) from expectation. In addition to\nidentifying the sources of deviation in unipolar and bipolar two-band systems,\na number of analytical expressions useful for quantifying the size of the\neffect are derived. As representative case-studies, a three-band model of the\nmaterials of lead telluride (PbTe) and tin sellenide (SnSe), which are\nimportant thermoelectric materials, is also developed and the size of possible\nLorenz number variations in these materials explored. Thus, the consequence of\nmulti-band effects on the Lorenz number of real systems is demonstrated.",
        "positive": "Giant mesoscopic fluctuations of the elastic cotunneling thermopower of\n  a single-electron transistor: We study the thermoelectric transport of a small metallic island weakly\ncoupled to two electrodes by tunnel junctions. In the Coulomb blockade regime,\nin the case when the ground state of the system corresponds to an even number\nof electrons on the island, the main mechanism of electron transport at lowest\ntemperatures is elastic cotunneling. In this regime, the transport coefficients\nstrongly depend on the realization of the random impurity potential or the\nshape of the island. Using the random-matrix theory, we calculate the\nthermopower and the thermoelectric kinetic coefficient and study the statistics\nof their mesoscopic fluctuations in the elastic cotunneling regime. The\nfluctuations of the thermopower turn out to be much larger than the average\nvalue."
    },
    {
        "anchor": "Quantum transport via evanescent waves in undoped graphene: Charge carriers in graphene are chiral quasiparticles (\"massless Dirac\nfermions\"). Graphene provides therefore an amazing opportunity to study subtle\nquantum relativistic effects in condensed matter experiment. Here I review a\ntheory of one of these unusual features of graphene, a \"pseudodiffusive\"\ntransport in the limit of zero charge carrier concentration, which is related\nto existence of zero-modes of the Dirac operator and to the Zitterbewegung of\nunltrarelativistic particles. A conformal mapping technique is a powerful\nmathematical tool to study these phenomena, as demonstrated here, using the\nAharonov-Bohm effect in graphene rings with Corbino geometry as an example.",
        "positive": "Generalization of Benalcazar-Bernevig-Hughes model to arbitrary\n  dimensions: The Benalcazar-Bernevig-Hughes (BBH) model [Science 357, 61 (2017)],\nfeaturing bulk quadrupole moment, edge dipole moments, and corner states, is a\nparadigm of both higher-order topological insulators and topological multipole\ninsulators. In this work, we generalize the BBH model to arbitrary dimensions\nby utilizing the Clifford algebra. For the generalized BBH model, the\nanalytical solution of corner states can be directly constructed in a unified\nway. Based on the solution of corner states and chiral symmetry analysis, we\ndevelop a general boundary projection method to extract the boundary\nHamiltonians, which turns out to be the BBH models of lower dimension and\nreveals the dimensional hierarchy."
    },
    {
        "anchor": "Diffusion thermopower of a $p-$type Si/Si$_{1-x}$Ge$_x$ heterostructure\n  at zero magnetic field: We calculate the diffusion thermopower of the degenerate two-dimensional hole\ngas in a $p-$type Si/Si$_{1-x}$Ge$_x$ lattice mismatched heterostructure at low\ntemperatures and zero magnetic field. The effects of possible scatterings, e.g.\nremote impurity, alloy disorder, interface roughness, deformation potential,\nand random piezoelectric on the hole mobility and the diffusion thermopower are\nexamined. Calculated results are well fitted to the experimental data recently\nreported. In addition, we predict a possibility for the diffusion thermopower\nto change its sign as the SiGe layer thickness changes, the effect has not been\ndiscussed yet.",
        "positive": "Chiral Hinge Magnons in Second-Order Topological Magnon Insulators: When interacting spins in condensed matter order ferromagnetically, their\nground state wave function is topologically trivial. Nonetheless, in two\ndimensions, the ferromagnetic state can support spin excitations with\nnontrivial topology, an exotic state known as topological magnon insulator\n(TMI). Here, we theoretically unveil and numerically confirm a novel\nferromagnetic state in three dimensions dubbed second-order TMI, whose\nhallmarks are excitations at its hinges, where facets intersect. Since\nferromagnetism naturally comes with broken time-reversal symmetry, the hinge\nmagnons are chiral, rendering backscattering impossible. Hence, they trace out\na three-dimensional path about the sample unimpeded by defects and are\ntopologically protected by the spectral gap. They are remarkably robust against\ndisorder and simultaneously highly tunable by atomic-level engineering of the\nsample termination. Our findings empower magnonics with the tools of\nhigher-order topology, a promising route to combine low-energy information\ntransfer free of Joule heating with three-dimensional vertical integration."
    },
    {
        "anchor": "Straightforward Bias and Frequency Dependent Small-Signal Model\n  Extraction for Single-Layer Graphene FETs: We propose an explicit small-signal graphene field-effect transistor (GFET)\nparameter extraction procedure based on a charge-based quasi-static model. The\ndependence of the small-signal parameters on both gate voltage and frequency is\nprecisely validated by high-frequency (up to 18 GHz) on-wafer measurements from\na 300 nm device. These parameters are studied simultaneously, in contrast to\nother works which focus exclusively on few. Efficient procedures have been\napplied to GFETs for the first time to remove contact and gate resistances from\nthe Y-parameters. The use of these methods yields straightforward equations for\nextracting the small-signal model parameters, which is extremely useful for\nradio-frequency circuit design. Furthermore, we show for the first time\nexperimental validation vs. both gate voltage and frequency of the intrinsic\nGFET non-reciprocal capacitance model. Accurate models are also presented for\nthe gate voltage-dependence of the measured unity-gain and maximum oscillation\nfrequencies as well as of the current and power gains.",
        "positive": "Local signatures of electron-electron scattering in an electronic cavity: We image equilibrium and non-equilibrium transport through a two-dimensional\nelectronic cavity using scanning gate microscopy (SGM). Injecting electrons\ninto the cavity through a quantum point contact close to equilibrium, we\nraster-scan a weakly invasive tip above the cavity regions and measure the\nmodulated conductance through the cavity. Varying the electron injection energy\nbetween $\\pm$ 2 meV, we observe that conductance minima turn into maxima beyond\nthe energy threshold of $\\pm$ 0.6 meV. This observation bears similarity to\nprevious measurements by Jura et al. [Jura et al., Phys. Rev. B 82, 155328\n(2010)] who used a strongly invasive tip potential to study electron injection\ninto an open two-dimensional electron gas. This resemblance suggests a similar\nmicroscopic origin based on electron-electron interactions."
    },
    {
        "anchor": "Topological invariant in three-dimensional band insulators with disorder: Topological insulators in three dimensions are characterized by a Z2-valued\ntopological invariant, which consists of a strong index and three weak indices.\nIn the presence of disorder, only the strong index survives. This paper studies\nthe topological invariant in disordered three-dimensional system by viewing it\nas a super-cell of an infinite periodic system. As an application of this\nmethod we show that the strong index becomes non-trivial when strong enough\ndisorder is introduced into a trivial insulator with spin-orbit coupling,\nrealizing a strong topological Anderson insulator. We also numerically extract\nthe gap range and determine the phase boundaries of this topological phase,\nwhich ?ts well with those obtained from self-consistent Born approximation\n(SCBA) and the transport calculations.",
        "positive": "Two-dimensional chiral stacking orders in quasi-one-dimensional charge\n  density waves: Chirality manifests in various forms in nature. However, there is no evidence\nof the chirality in one-dimensional charge density wave (CDW) systems. Here, we\nhave explored the chirality among quasi-one-dimensional CDW ground states with\nthe aid of scanning tunneling microscopy, symmetry analysis, and density\nfunctional theory calculations. We discovered three distinct chiralities\nemerging in the form of two-dimensional chiral stacking orders composed of\ndegenerate CDW ground states: right-, left-, and nonchiral stacking orders.\nSuch chiral stacking orders correspond to newly introduced chiral winding\nnumbers. Furthermore, we observed that these chiral stacking orders are\nintertwined with chiral vortices and chiral domain walls, which play a crucial\nrole in engineering the chiral stacking orders. Our findings suggest that the\nunexpected chiral stacking orders can open a way to investigate the chirality\nin CDW systems, which can lead to diverse phenomena such as circular dichroism\ndepending on chirality."
    },
    {
        "anchor": "Comment on \"Photoluminescence ring formation in coupled quantum wells:\n  Excitonic versus ambipolar diffusion\": This is a comment on M. Stern, V. Garmider, E. Segre, M. Rappaport, V.\nUmansky, Y. Levinson, and I. Bar-Joseph, Phys. Rev. Lett. 101, 257402 (2008).",
        "positive": "Double roton-minima in bosonic fractional quantum Hall states: We have studied the collective spin-conserving collective excitation spectra\nin rotating diluted ultra-cold Bose atoms. Double roton-minima have been\nobserved in the fractional quantum Hall (FQH) states for the two filling\nfractions ($\\nu$) of the first series of Jain's composite fermion sequences.\nThe obtained roton-minima for $\\nu$ = 1/4 are at the wave-vectors 1.26 and 2.38\nand the roton-minima for $\\nu$ = 1/6 have been shifted to 1.08 and 2.06. Such\nshift of roton-minima is attributed due to strong correlation between the\nparticles in bosonic FQH-system. Moreover, the number of roton minima observed\ndepends upon number of attached fluxes as well as the ranges of interaction\nbetween the particles."
    },
    {
        "anchor": "Quantum transport in electron Fabry-Perot interferometers: We report experiments on Fabry-Perot electron interferometers in the integer\nquantum Hall regime. The GaAs/AlGaAs heterostructure devices consist of two\nconstrictions defined by etch trenches in 2D electron layer, enclosing an\napproximately circular island. The interferometer is formed by\ncounterpropagating chiral edge channels coupled by tunneling in the two\nconstrictions. Interference fringes are observed as conductance oscillations,\nsimilar to the Aharonov-Bohm effect. Front gates deposited in etch trenches\nallow to fine-tune the device and to change the constriction filling f relative\nto the bulk filling. Quantum-coherent conductance oscillations are observed on\nthe f = 1 - 4 plateaus. On plateau f we observe f conductance oscillations per\nfundamental flux period h/e. This is attributed to the dominance of the\nelectron-electron Coulomb interaction, effectively mixing Landau level\noccupation. On the other hand, the back-gate charge period is the same (one\nelectron) on all plateaus, independent of filling. This is attributed to the\nself-consistent electrostatics in the large electron island. We also report\ndependence of the oscillation period on front-gate voltage for f = 1, 2 and 4\nfor three devices. We find a linear dependence, with the slope inversely\nproportional to f for f = 1 and 2.",
        "positive": "Weak antilocalization in epitaxial graphene: evidence for chiral\n  electrons: Transport in ultrathin graphite grown on silicon carbide is dominated by the\nelectron-doped epitaxial layer at the interface. Weak anti-localization in 2D\nsamples manifests itself as a broad cusp-like depression in the longitudinal\nresistance for magnetic fields 10 mT$< B <$ 5 T. An extremely sharp\nweak-localization resistance peak at B=0 is also observed. These features\nquantitatively agree with graphene weak-(anti)localization theory implying the\nchiral electronic character of the samples. Scattering contributions from the\ntrapped charges in the substrate and from trigonal warping due to the graphite\nlayer on top are tentatively identified. The Shubnikov-de Haas oscillations are\nremarkably small and show an anomalous Berry's phase."
    },
    {
        "anchor": "Continuous quantum measurement with independent detector\n  cross-correlations: We investigate the advantages of using two independent, linear detectors for\ncontinuous quantum measurement. For single-shot quantum measurement, the\nmeasurement is maximally efficient if the detectors are twins. For weak\ncontinuous measurement, cross-correlations allow a violation of the\nKorotkov-Averin bound for the detector's signal-to-noise ratio. A vanishing\nnoise background provides a nontrivial test of ideal independent quantum\ndetectors. We further investigate the correlations of non-commuting operators,\nand consider possible deviations from the independent detector model for\nmesoscopic conductors coupled by the screened Coulomb interaction.",
        "positive": "An efficient method for quantum transport simulations in the time domain: An approximate method based on adiabatic time dependent density functional\ntheory (TDDFT) is presented, that allows for the description of the electron\ndynamics in nanoscale junctions under arbitrary time dependent external\npotentials. In this scheme, the density matrix of the device region is\npropagated according to the Liouville-von Neumann equation. The semi-infinite\nleads give rise to dissipative terms in the equation of motion which are\ncalculated from first principles in the wide band limit. In contrast to earlier\n{\\em ab-initio} implementations of this formalism, the Hamiltonian is here\napproximated by a density expansion in the spirit of the density functional\nbased tight-binding (DFTB) method without introducing empirical parameters.\nResults are presented for two prototypical molecular devices and compared to\ncalculations at the full TDDFT level. The issue of non-existence of a steady\nstate under certain conditions is also briefly touched on."
    },
    {
        "anchor": "Dynamics of Density Imbalanced Bilayer Holes in the Quantum Hall Regime: We report magnetotransport measurements on bilayer GaAs hole systems with\nunequal hole concentrations in the two layers. At magnetic fields where one\nlayer is in the integer quantum Hall state and the other has bulk extended\nstates at the Fermi energy, the longitudinal and Hall resistances of the latter\nare hysteretic, in agreement with previous measurements. For a fixed magnetic\nfield inside this region and at low temperatures ($T\\le$ 350 mK), the time\nevolutions of the longitudinal and Hall resistances show pronounced jumps\nfollowed by slow relaxations, with no end to the sequence of jumps. Our\nmeasurements demonstrate that the jumps occur simultaneously in pairs of\ncontacts 170 $\\mu$m apart, and appear to involve changes in the charge\nconfiguration of the bilayer. In addition, the jumps can occur with either\nrandom or regular periods, excluding thermal fluctuations as a possible origin\nfor the jumps. Finally, while remaining at a fixed field, we warm the sample to\nabove 350 mK, where the jumps disappear. Upon recooling the sample below this\ntemperature, the jumps reappear, indicating that the jumps do not result from\nnearly dissipationless eddy currents either.",
        "positive": "Spatial and energy resolution of electronic states by shot noise: Shot noise measurements are widely used for the characterization of\nnonequilibrium configurations in electronic conductors. The recently introduced\nquantum tomography approach was implemented for the studies of electronic\nwavefunctions of few-electron excitations created by periodic voltage pulses in\nphase-coherent ballistic conductors based on the high-quality GaAs\ntwo-dimensional electron gas. Still relying on the manifestation of Fermi\ncorrelations in noise, we focus on the simpler and more general approach\nbeneficial for the local measurements of energy distribution (ED) in electronic\nsystems with arbitrary excitations with well-defined energies and random\nphases. Using biased diffusive metallic wire as a testbed, we demonstrate the\npower of this approach and extract the well-known double-step ED from the shot\nnoise of a weakly coupled tunnel junction. Our experiment paves the way for the\nlocal measurements of generic nonequilibrium configurations applicable to\nvirtually any conductor."
    },
    {
        "anchor": "Control of fluorescence in quantum emitter and metallic nanoshell\n  hybrids for medical applications: We study the light emission from quantum emitter and double metallic\nnanoshell hybrid systems. Quantum emitters act as local sources which transmit\ntheir light efficiently due to a double nanoshell near field. The double\nnanoshell consists a dielectric core and two outer nanoshells.",
        "positive": "Currentless reversal of N\u00e9el vector in antiferromagnets: The bias driven perpendicular magnetic anisotropy is a magneto-electric\neffect that can realize 90$^\\circ$ magnetization rotation and even 180$% ^\\circ\n$ flip along the easy axis in the ferromagnets with a minimal energy\nconsumption. This study theoretically demonstrates a similar phenomenon of the\nN\\'{e}el vector reversal via a short electrical pulse that can mediate\nperpendicular magnetic anisotropy in the antiferromagnets. The analysis based\non the dynamical equations as well as the micro-magnetic simulations reveals\nthe important role of the inertial behavior in the antiferromagnets that\nfacilitates the N\\'{e}el vector to overcome the barrier between two free-energy\nminima of the bistable states along the easy axis. In contrast to the\nferromagnets, this N\\'{e}el vector reversal does not accompany angular moment\ntransfer to the environment, leading to acceleration in the dynamical response\nby a few orders of magnitude. Further, a small switching energy requirement of\na few attojoules illustrates an added advantage of the phenomenon in low-power\nspintronic applications."
    },
    {
        "anchor": "Interplay of relativistic and nonrelativistic transport in atomically\n  precise segmented graphene nanoribbons: Graphene's isolation launched explorations of fundamental relativistic\nphysics originating from the planar honeycomb lattice arrangement of the carbon\natoms, and of potential technological applications in nanoscale electronics.\nBottom-up fabricated atomically-precise segmented graphene nanoribbons, SGNRs,\nopen avenues for studies of electrical transport, coherence, and interference\neffects in metallic, semiconducting, and mixed GNRs, with different edge\nterminations. Conceptual and practical understanding of electric transport\nthrough SGNRs is gained through nonequilibrium Green's function (NEGF)\nconductance calculations and a Dirac continuum model that absorbs the\nvalence-to-conductance energy gaps as position-dependent masses, including\ntopological-in-origin mass-barriers at the contacts between segments. The\ncontinuum model reproduces the NEGF results, including optical Dirac\nFabry-Perot (FP) equidistant oscillations for massless relativistic carriers in\nmetallic armchair SGNRs, and an unequally-spaced FP pattern for mixed\narmchair-zigzag SGNRs where carriers transit from a relativistic (armchair) to\na nonrelativistic (zigzag) regime. This provides a unifying framework for\nanalysis of coherent transport phenomena and interpretation of forthcoming\nexperiments in SGNRs.",
        "positive": "Dark trions govern the temperature-dependent optical absorption and\n  emission of doped atomically thin semiconductors: We perform absorption and photoluminescence spectroscopy of trions in\nhBN-encapsulated WSe$_2$, WS$_2$, MoSe$_2$, and MoS$_2$ monolayers, depending\non temperature. The different trends for W- and Mo-based materials are\nexcellently reproduced considering a Fermi-Dirac distribution of bright and\ndark trions. We find a dark trion, $\\rm{X_D^-}$ 19 meV $\\textit{below}$ the\nlowest bright trion, $\\rm{X}_1^-$ in WSe$_2$ and WS$_2$. In MoSe$_2$,\n$\\rm{X_D^-}$ lies 6 meV $\\textit{above}$ $\\rm{X}_1^-$, while $\\rm{X_D^-}$ and\n$\\rm{X}_1^-$ almost coincide in MoS$_2$. Our results agree with GW-BSE\n$\\textit{ab-initio}$ calculations and quantitatively explain the optical\nresponse of doped monolayers with temperature."
    },
    {
        "anchor": "Gap-tunable of Tunneling Time in Graphene Magnetic Barrier: We study the tunneling time of Dirac fermions in graphene magnetic barrier\nthrough an electrostatic potential and a mass term. This latter generates an\nenergy gap in the spectrum and therefore affects the proprieties of tunneling\nof the system. For clarification, we first start by deriving the eigenspinors\nsolutions of Dirac equation and second connect them to the incident, reflected\nand transmitted beam waves. This connection allows us to obtain the\ncorresponding phases shifts and consequently compute the group delay time in\ntransmission and reflection. Our numerical results show that the group delay\ntime depends strongly on the energy gap in the tunneling process through single\nbarrier. Moreover, we find that the group approaches unity at some critical\nvalue of the energy gap and becomes independent to the strengths of involved\nphysical parameters.",
        "positive": "Enhanced Photodetection in Graphene-Integrated Photonic Crystal Cavity: We demonstrate the controlled enhancement of photoresponsivity in a graphene\nphotodetector by coupling to slow light modes in a long photonic crystal linear\ndefect cavity. Near the Brillouin zone (BZ) boundary, spectral coupling of\nmultiple cavity modes results in broad-band photocurrent enhancement from 1530\nnm to 1540 nm. Away from the BZ boundary, individual cavity resonances enhance\nthe photocurrent eight-fold in narrow resonant peaks. Optimization of the\nphotocurrent via critical coupling of the incident field with the\ngraphene-cavity system is discussed. The enhanced photocurrent demonstrates the\nfeasibility of a wavelength-scale graphene photodetector for efficient\nphotodetection with high spectral selectivity and broadband response."
    },
    {
        "anchor": "Radiation effects on the electronic structure of bilayer graphene: We report on the effects of laser illumination on the electronic properties\nof bilayer graphene. By using Floquet theory combined with Green's functions we\nunveil the appeareance of laser-induced gaps not only at integer multiples of\n$\\hbar \\Omega /2$ but also at the Dirac point with features which are shown to\ndepend strongly on the laser polarization. Trigonal warping corrections are\nshown to lead to important corrections for radiation in the THz range, reducing\nthe size of the dynamical gaps. Furthermore, our analysis of the topological\nproperties at low energies reveals that when irradiated with linearly polarized\nlight, ideal bilayer graphene behaves as a trivial insulator, whereas circular\npolarization leads to a non-trivial insulator per valley.",
        "positive": "Straintronics: Manipulating the Magnetization of Magnetostrictive\n  Nanomagnets with Strain for Energy-Efficient Applications: The desire to perform information processing, computation, communication,\nsignal generation and related tasks, while dissipating as little energy as\npossible, has inspired many ideas and paradigms. One of the most powerful among\nthem is the notion of using magnetostrictive nanomagnets as the primitive units\nof the hardware platforms and manipulating their magnetizations with\nelectrically generated static or time varying mechanical strain to elicit\nmyriad functionalities. This approach has two advantages. First, information\ncan be retained in the devices after powering off since the nanomagnets are\nnon-volatile unlike charge-based devices such as transistors. Second, the\nenergy expended to perform a given task is exceptionally low since it takes\nvery little energy to alter magnetization states with strain. This field is now\nknown as \"straintronics\", in analogy with electronics, spintronics,\nvalleytronics, etc. We review the recent advances and trends in straintronics,\nincluding digital information processing (logic), information storage (memory),\ndomain wall devices operated with strain, control of skyrmions with strain,\nnon-Boolean computing and machine learning with straintronics, signal\ngeneration (microwave sources) and communication (ultra-miniaturized acoustic\nand electromagnetic antennas) implemented with strained nanomagnets, hybrid\nstraintronics-magnonics, and interaction between phonons and magnons in\nstraintronic systems. We identify key challenges and opportunities, and lay out\npathways to advance this field to the point where it might become a mainstream\ntechnology for energy-efficient systems."
    },
    {
        "anchor": "Chirality effects in carbon nanotubes: We consider chirality related effects in optical, photogalvanic and\nelectron-transport properties of carbon nanotubes. We show that these\nproperties of chiral nanotubes are determined by terms in the electron\neffective Hamiltonian describing the coupling between the electron wavevector\nalong the tube principal axis and the orbital momentum around the tube\ncircumference. We develop a theory of photogalvanic effects and a theory of\nd.c. electric current, which is linear in the magnetic field and quadratic in\nthe bias voltage. Moreover, we present analytic estimations for the natural\ncircular dichroism and magneto-spatial effect in the light absorption.",
        "positive": "Dynamical density response and collective modes of topological insulator\n  ultra-thin films: We analytically calculate the intra- and inter-surface dynamical\ndensity-density linear responses of ultra-thin topological insulator films with\nfinite tunneling between their top and bottom surfaces in both metallic and\ninsulating regimes. Employing the random phase approximation we investigate the\ndispersions of in-phase and out-of-phase collective density modes of this\nsystem in the metallic regime. We find that in contrast to the bilayers of the\nconventional two-dimensional electron gas, where finite tunneling gaps out the\nout-of-phase mode, in topological insulator thin films, this mode remains\nlinear at long wavelengths. Depending on different system parameters, the\nvelocity of out-of-phase mode can be tuned to be larger or substantially\nsmaller than the Fermi velocity of electrons on the isolated surfaces of the\ntopological insulator. Finite tunneling generally reduces the energy of\ncollective modes, making them more confined in space."
    },
    {
        "anchor": "Acoustic spin-Chern insulator induced by synthetic spin-orbit coupling\n  with spin conservation breaking: Topologically protected surface modes of classical waves hold the promise to\nenable a variety of applications ranging from robust transport of energy to\nreliable information processing networks. The integer quantum Hall effect has\ndelivered on that promise in the electronic realm through high-precision\nmetrology devices. However, both the route of implementing an analogue of the\nquantum Hall effect as well as the quantum spin Hall effect are obstructed for\nacoustics by the requirement of a magnetic field, or the presence of fermionic\nquantum statistics, respectively. Here, we use a two-dimensional acoustic\ncrystal with two layers to mimic spin-orbit coupling, a crucial ingredient of\ntopological insulators. In particular, our setup allows us to free ourselves of\nsymmetry constraints as we rely on the concept of a non-vanishing \"spin\" Chern\nnumber. We experimentally characterize the emerging boundary states which we\nshow to be gapless and helical. Moreover, in an H-shaped device we demonstrate\nhow the transport path can be selected by tuning the geometry, enabling the\nconstruction of complex networks.",
        "positive": "Surface stress effects on the electrostatic pull-in instability of\n  nanomechanical systems: The electrostatic pull-in instability (EPI), within the framework of the\nnanoelectromechanical systems (NEMS) has been shown as a robust and versatile\nmethod for characterizing mechanical properties of nanocantilevers. This paper\naims to investigate the surface effects, specifically residual surface stress\nand surface elasticity, on the EPI of micro and nano-scale cantilevers as well\nas double clamped beams. Since the cantilever has one end free, it has no\nresidual stress, thus the strain-independent component of the surface stress or\nintrinsic surface stress has no influence on the EPI, as long as it has small\ndeformation. The strain-dependent component of the surface stress or surface\nelasticity changes the bending stiffness of the cantilever and, consequently,\ninduces shifts in the EPI. For double clamped beams, the effective residual\nsurface stress comes into play and modifies the effective residual stress of\nthe beam. The nonlinear electromechanical coupled equations, which take into\naccount the surface effects are solved numerically. The theoretical results\npresented in this paper indicate that the EPI is very sensitive to the surface\neffects, especially when a double clamped beam is employed. The results show\nthat the influence of surface effects on the EPI of cantilevers become more\nprofound when the thickness is below 50 nm, while the influence on double\nclamped beams is significant even at sub-micron scale. The present study can\nprovide helpful insights for the design and characterization of NEMS switches.\nMoreover, the results can be used to provide the proof of concepts of a new\nsurface stress sensing method using EPI in nanomechanical sensor systems."
    },
    {
        "anchor": "High-energy long-lived resonance of electrons in fractal-like\n  semiconductor heterostructures: A fractal-like alignment of quantum wells is shown to accommodate resonant\nstates with long lifetimes. For the parameters of the semiconductor\nheterostructure GaAs/Al$_{0.4}$Ga$_{0.6}$As with the well depth 300meV, a\nresonant state of the energy as high as 44meV with the lifetime as long as\n2.8\\{mu}s is shown to be achievable.",
        "positive": "Voltage-Controlled Nano-Scale Reconfigurable Magnonic Crystal: A nano-scale reconfigurable magnonic crystal is designed using\nvoltage-controlled perpendicular magnetic anisotropy (PMA) in\nferromagnetic-dielectric hetero-structures. A periodic array of gate metallic\nstripes is placed on top of a MgO/Co structure in order to apply a periodic\nelectric field and to modify the PMA in Co. It is numerically demonstrated that\nthe application of the voltage to the gate stripes modifies the spin-wave\npropagation and leads to the formation of band gaps in the spin-wave spectrum.\nThe band gaps are dynamically controllable, i.e. it is possible to switch band\ngaps on and off within a few nanoseconds. The width and the center frequency of\nthe band gaps is defined by the applied voltage. At last, it is shown that the\napplication of the voltage to selected, rather than to all gate stripes allows\nfor a pre-defined modification of the band gap spectra. The proposed\nvoltage-controlled reconfigurable magnonic crystal opens a new way to low power\nconsumption magnonic applications."
    },
    {
        "anchor": "Topological phases of polaritons in a cavity waveguide: We study the unconventional topological phases of polaritons inside a cavity\nwaveguide, demonstrating how strong light-matter coupling leads to a breakdown\nof the bulk-edge correspondence. Namely, we observe an ostensibly topologically\nnontrivial phase, which unexpectedly does not exhibit edge states. Our findings\nare in direct contrast to topological tight-binding models with electrons, such\nas the celebrated Su-Schrieffer-Heeger (SSH) model. We present a theory of\ncollective polaritonic excitations in a dimerized chain of oscillating dipoles\nembedded inside a photonic cavity. The added degree of freedom from the cavity\nphotons upgrades the system from a typical SSH $\\mathrm{SU}(2)$ model into a\nlargely unexplored $\\mathrm{SU}(3)$ model. Tuning the light-matter coupling\nstrength by changing the cavity size reveals three critical points in parameter\nspace: when the polariton band gap closes, when the Zak phase changes from\nbeing trivial to nontrivial, and when the edge state is lost. Remarkably, these\nthree critical points do not coincide, and thus the Zak phase is no longer an\nindicator of the presence of edge states. Our discoveries demonstrate some\nremarkable properties of topological matter when strongly coupled to light, and\ncould be important for the growing field of topological nanophotonics.",
        "positive": "AC and DC Conductivities in an n-GaAs/AlAs Heterostructure with a Wide\n  Quantum Well in the Integer Quantum Hall Effect Regime: The direct-current (dc) $\\sigma_{xx}^{dc}$ and alternating-current (ac)\n$\\sigma_{xx}^{ac}=\\sigma_1-i\\sigma_2$ conductivities of a wide (46 nm) GaAs\nquantum well with the bilayer electron density distribution are measured. It is\nfound that the magnetic field dependence of $\\sigma_{xx}$ exhibits three sets\nof oscillations related to the transitions between Landau levels in symmetric\nand antisymmetric subbands and with the transitions occurring owing to the\nZeeman splitting of these subbands. The analysis of the frequency dependence of\nthe ac conductivity and the $\\sigma_1 / \\sigma_2$ ratio demonstrates that the\nconductivity at the minima of oscillations is determined by the hopping\nmechanism."
    },
    {
        "anchor": "Third harmonic generation in graphene and few-layer graphite films: We observe optical third harmonic generation from graphene and few-layer\ngraphite flakes produced by exfoliation. The emission scales with the cube of\nthe intensity of the incident near-infrared femtosecond pulses and has a\nwavelength that is one-third of the incident wavelength, both consistent with\nthird harmonic generation. We extract an effective third-order susceptibility\nfor graphene that is on the order of 1e-16 square meter per square volt, which\nis comparable to that for materials that are resonantly excited, but larger\nthan for materials that are transparent at the fundamental and third harmonic\nwavelengths. By measuring a set of flakes with different numbers of atomic\nlayers, we find that the emission scales with the square of the number of\natomic layers, which suggests that the susceptibility of graphene is\nindependent of layer number, at least for a few layers.",
        "positive": "Novel excitonic states in quantum Hall systems: Bound states of spin\n  waves and a valence band hole: If the Zeeman energy is small, the lowest energy excitations of a two\ndimensional electron gas at filling factor nu=1 are spin waves (spin flip\nexcitations). At nu slightly larger (smaller) than unity, reversed spin\nelectrons (spin holes) can form bound states with K spin waves that are known\nas skyrmions, S_K^- (antiskyrmions, S_K^+). It is suggested in this work that a\nvalence hole can also bind K spin waves to form an excitonic complex X_K^+,\nanalogous to the S_K^+. One spin hole of the S_K^+ is simply replaced by the\nvalence hole. At nu<=1, a small number of S_K^+'s are present before\nintroduction of the valence hole. The (S_K^+)-(X_K^+) repulsion leads to\ncorrelations and photoluminescence similar to those of a dilute\nelectron-(charged-exciton) (e-X^-) system at nu<=1/3. At nu>=1, the\n(S_K^-)-(X_K^+) attraction can potentially lead to different behavior."
    },
    {
        "anchor": "Double bit in-plane magnetic skyrmions on a track: A magnetic skyrmion isusually refers to a twisted spin texture surrounded by\nuniformly aligned out-of-plane spinsin the background of a uniformly magnetized\nstate. The invariance of the magnetic skyrmion conserves its topological charge\nunder any continuous transformations of the spin textures, leads to which\nrepresents the robustness of a magnetic skyrmion their texture against external\nperturbations, making it ideal to use skyrmions as . Such a behaviour is\nrequired for an ideal information carriers. To date, most magnetic skyrmion\nstudies have been performedfocused on in perpendicularly magnetized systems,\nwhere the skyrmion topological number is determined by the relative orientation\nbetween the core and /outer perpendicular magnetization directions of the\nskyrmion is either up/down or down/up. Here we show that there also exists a\nnew type of magnetic skyrmion with surrounding spins to be uniformly aligned to\nthe in-plane direction. By continuous transformation and relaxation of the spin\ntextures of out-of-plane skyrmions, we showed that an in-plane skyrmion, where\nthe background magnetization is in the in-plane direction, is also possible.\nDifferent from the conventional perpendicular magnetic skyrmionsContrary to the\nskyrmions in a perpendicularly magnetized state, the in-plane magnetic\nskyrmions with opposite signs of topological charges can inherentlycharges can\ninherently coexist in the in-plane magnetization system coexist. Moreover, the\niIn-plane skyrmions of opposite charge can move together by an electric current\nand exhibit with an opposite spin Hall effect. These findings showdemonstrate\nthe inherent possibility of a double-bit transfer in a single magnetic wire\nthat is not possible in a perpendicularly magnetized system.",
        "positive": "The effect of the Abrikosov vortex phase on spin and charge states in\n  magnetic semiconductor-superconductor hybrids: We explore the possibility of using the inhomogeneous magnetic field carried\nby an Abrikosov vortex in a type-II superconductor to localize spin-polarized\ntextures in a nearby magnetic semiconductor quantum well. We show how\nZeeman-induced localization induced by a single vortex is indeed possible, and\nuse these results to investigate the effect of a periodic vortex array on the\ntransport properties of the magnetic semiconductor. In particular, we find an\nunconventional Integer Quantum Hall regime, and predict directly testable\nexperimental consequences due to the presence of the periodic spin polarized\nstructure induced by the superconducting vortex lattice in the magnetic\nsemiconductor."
    },
    {
        "anchor": "Low-energy Electron Reflectivity from Graphene: First-Principles\n  Computations and Approximate Models: A computational method is developed whereby the reflectivity of low-energy\nelectrons from a surface can be obtained from a first-principles solution of\nthe electronic structure of the system. The method is applied to multilayer\ngraphene. Two bands of reflectivity minima are found, one at 0 - 8 eV and the\nother at 14 - 22 eV above the vacuum level. For a free-standing slab with n\nlayers of graphene, each band contains n-1 zeroes in the reflectivity. Two\nadditional image-potential type states form at the ends of the graphene slab,\nwith energies just below the vacuum level, hence producing a total of 2n\nstates. A tight-binding model is developed, with basis functions localized in\nthe spaces between the graphene planes (and at the ends of the slab). The\nspectrum of states produced by the tight-binding model is found to be in good\nagreement with the zeros of reflectivity (i.e. transmission resonances) of the\nfirst-principles results.",
        "positive": "Theory of Quantum Hall Nematics: Transport measurements on two dimensional electron systems in moderate\nmagnetic fields suggest the existence of a spontaneously\norientationally-ordered, compressible liquid state. We develop and analyze a\nmicroscopic theory of such a ``quantum Hall nematic'' (QHN) phase, predict the\nexistence of a novel, highly anisotropic $q^3$ density-director mode, find that\nthe T=0 long-range orientational order is unstable to weak disorder, and\ncompute the tunneling into such a strongly correlated state. This microscopic\napproach is supported and complemented by a hydrodynamic model of the QHN,\nwhich, in the dissipationless limit, reproduces the modes of the microscopic\nmodel."
    },
    {
        "anchor": "Electrical spectroscopy of the spin-wave dispersion and bistability in\n  gallium-doped yttrium iron garnet: Yttrium iron garnet (YIG) is a magnetic insulator with record-low damping,\nallowing spin-wave transport over macroscopic distances. Doping YIG with\ngallium ions greatly reduces the demagnetizing field and introduces a\nperpendicular magnetic anisotropy, which leads to an isotropic spin-wave\ndispersion that facilitates spin-wave optics and spin-wave steering. Here, we\ncharacterize the dispersion of a gallium-doped YIG (Ga:YIG) thin film using\nelectrical spectroscopy. We determine the magnetic anisotropy parameters from\nthe ferromagnetic resonance frequency and use propagating spin wave\nspectroscopy in the Damon-Eshbach configuration to detect the small spin-wave\nmagnetic fields of this ultrathin weak magnet over a wide range of wavevectors,\nenabling the extraction of the exchange constant $\\alpha=1.3(2)\\times10^{-12}$\nJ/m. The frequencies of the spin waves shift with increasing drive power, which\neventually leads to the foldover of the spin-wave modes. Our results shed light\non isotropic spin-wave transport in Ga:YIG and highlight the potential of\nelectrical spectroscopy to map out the dispersion and bistability of\npropagating spin waves in magnets with a low saturation magnetization.",
        "positive": "Adiabatic quantum pumping and rectification effects in interacting\n  quantum dots: We derive a formula describing the adiabatically pumped charge through an\ninteracting quantum dot within the scattering matrix and Green's function\napproach. We show that when the tunneling rates between the leads and the dot\nare varied adiabatically in time, both in modulus and phase, the current\ninduced in the dot consists of two terms, the pumping current and a\nrectification-like term. The last contribution arises from the time-derivative\nof the tunneling phase and can have even or odd parity with respect to the\npumping phase \\varphi. The rectification-like term is also discussed in\nrelation to some recent experiments in quantum-dots."
    },
    {
        "anchor": "Dynamical strong coupling and parametric amplification in mechanical\n  modes of graphene drums: Mechanical resonators are ubiquitous in modern information technology. With\nthe ability to couple them to electromagnetic and plasmonic modes, they hold\nthe promise to be the key building blocks in future quantum information\ntechnology. Graphene based resonators are of interest for technological\napplications due to their high resonant frequencies, multiple mechanical modes,\nand low mass. The tension mediated non-linear coupling between various modes of\nthe resonator can be excited in a controllable manner. Here, we engineer a\ngraphene resonator to have large frequency tunability at low temperatures\nresulting in large intermodal coupling strength. We observe the emergence of\nnew eigenmodes and amplification of the coupled modes using red and blue\nparametric excitation respectively. We demonstrate that the dynamical\nintermodal coupling is tunable. A cooperativity of 60 between two resonant\nmodes of ~100 MHz is achieved in the strong coupling regime. The ability to\ndynamically control the coupling between high frequency eigenmodes of a\nmechanical system opens up possibility for quantum mechanical experiments at\nlow temperatures.",
        "positive": "Dimensional transmutation from non-Hermiticity: Dimensionality plays a fundamental role in the classification of novel phases\nand their responses. In generic lattices of 2D and beyond, however, we found\nthat non-Hermitian couplings do not merely distort the Brillouin zone (BZ), but\ncan in fact alter its effective dimensionality. This is due to the fundamental\nnon-commutativity of multi-dimensional non-Hermitian pumping, which obstructs\nthe usual formation of a generalized complex BZ. As such, basis states are\nforced to assume \"entangled\" profiles that are orthogonal in a lower\ndimensional effective BZ, completely divorced from any vestige of lattice Bloch\nstates unlike conventional skin states. Characterizing this reduced\ndimensionality is an emergent winding number intimately related to the homotopy\nof non-contractible spectral paths. We illustrate this dimensional\ntransmutation through a 2D model whose topological zero modes are protected by\na 1D, not 2D, topological invariant. Our findings can be readily demonstrated\nvia the bulk properties of non-reciprocally coupled platforms such as circuit\narrays, and provokes us to rethink about the fundamental role of geometric\nobstruction in the dimensional classification of topological states."
    },
    {
        "anchor": "Quantum Transport in Ambipolar Few-layer Black Phosphorus: Few-layer black phosphorus possesses unique electronic properties giving rise\nto distinct quantum phenomena and thus offers a fertile platform to explore the\nemergent correlation phenomena in low dimensions. A great progress has been\ndemonstrated in improving the quality of hole-doped few-layer black phosphorus\nand its quantum transport studies, whereas the same achievements are rather\nmodest for electron-doped few-layer black phosphorus. Here, we report the\nambipolar quantum transport in few-layer black phosphorus exhibiting\nundoubtedly the quantum Hall effect for hole transport and showing clear\nsignatures of the quantum Hall effect for electron transport. By bringing the\nspin-resolved Landau levels of the electron-doped black phosphorus to the\ncoincidence, we measure the spin susceptibility $\\chi_s=m^\\ast\ng^\\ast=1.1\\pm0.03$. This value is larger than for hole-doped black phosphorus\nand illustrates an energetically equidistant arrangement of spin-resolved\nLandau levels. Evidently, the n-type black phosphorus offers a unique platform\nwith equidistant sequence of spin-up and spin-down states for exploring the\nquantum spintronic.",
        "positive": "Modeling of graphene-based NEMS: The possibility of designing nanoelectromechanical systems (NEMS) based on\nrelative motion or vibrations of graphene layers is analyzed. Ab initio and\nempirical calculations of the potential relief of interlayer interaction energy\nin bilayer graphene are performed. A new potential based on the density\nfunctional theory calculations with the dispersion correction is developed to\nreliably reproduce the potential relief of interlayer interaction energy in\nbilayer graphene. Telescopic oscillations and small relative vibrations of\ngraphene layers are investigated using molecular dynamics simulations. It is\nshown that these vibrations are characterized with small Q-factor values. The\nperspectives of nanoelectromechanical systems based on relative motion or\nvibrations of graphene layers are discussed."
    },
    {
        "anchor": "Many-Body Physics in Small Systems: Observing the Onset and Saturation\n  of Correlation in Linear Atomic Chains: The exact study of small systems can guide us toward measures for extracting\ninformation about many-body physics as we move to more complex systems capable\nof quantum information processing or quantum analog simulation. We use exact\ndiagonalization to study many electrons in short 1-D atom chains represented by\nlong-range extended Hubbard-like models. We introduce a novel measure, the\nSingle-Particle Excitation Content (SPEC) of an eigenstate and show that the\ndependence of SPEC on state number reveals the nature of the ground state, and\nthe onset and saturation of correlation between the electrons as Coulomb\ninteraction strength increases. We use this SPEC behavior to identify five\nregimes as interaction is increased: a non-interacting single-particle regime,\na regime of perturbative Coulomb interaction in which the SPEC is a nearly\nuniversal function of state number, the onset and saturation of correlation, a\nregime of fully correlated states in which hopping is a perturbation and SPEC\nis a different universal function of state number, and the regime of no\nhopping. In particular, the behavior of the SPEC shows that when\nelectron-electron correlation plays a minor role, all of the lowest energy\nstates are made up primarily of single-particle excitations of the ground\nstate, and as the Coulomb interaction increases, the lowest energy states\nincreasingly contain many-particle excitations. In addition, the SPEC\nhighlights a fundamental, distinct difference between a non-interacting system\nand one with minute, very weak interactions. While SPEC is a quantity that can\nbe calculated for small exactly diagonalizable systems, it guides our intuition\nfor larger systems, suggesting the nature of excitations and their distribution\nin the spectrum. Thus, this function, like correlation functions or order\nparameters, provides us with a window of intuition about the behavior of a\nphysical system.",
        "positive": "Edge transport in InAs and InAs/GaSb quantum wells: We investigate low-temperature transport through single InAs quantum wells\nand broken-gap InAs/GaSb double quantum wells. Non-local measurements in the\nregime beyond bulk pinch-off confirm the presence of edge conduction in InAs\nquantum wells. The edge resistivity of 1-2 $\\mathrm{k\\Omega/\\mu m}$ is of the\nsame order of magnitude as edge resistivities measured in the InAs/GaSb double\nquantum well system. Measurements in tilted magnetic field suggests an\nanisotropy of the conducting regions at the edges with a larger extent in the\nplane of the sample than normal to it. Finger gate samples on both material\nsystems shine light on the length dependence of the edge resistance with the\nintent to unravel the nature of edge conduction in InAs/GaSb coupled quantum\nwells."
    },
    {
        "anchor": "Correlations of mutual positions of charge density waves nodes in\n  side-by-side placed InAs wires measured with scanning gate microscopy: We investigate the correlations of mutual positions of charge density waves\nnodes in side-by-side placed InAs nanowires in presence of a conductive atomic\nforce microscope tip served as a mobile gate at helium temperatures. Scanning\ngate microscopy scans demonstrate mutual correlation of positions of charge\ndensity waves nodes of two wires. A general mutual shift of the nodes positions\nand \"crystal lattice mismatch\" defect were observed. These observations\ndemonstrate the crucial role of Coulomb interaction in formation of charge\ndensity waves in InAs nanowires.",
        "positive": "Quantum transport in chemically functionalized graphene at high magnetic\n  field: Defect-Induced Critical States and Breakdown of Electron-Hole Symmetry: Unconventional magneto-transport fingerprints in the quantum Hall regime\n(with applied magnetic field from one to several tens of Tesla) in chemically\nfunctionalized graphene are reported. Upon chemical adsorption of monoatomic\noxygen (from 0.5% to few percents), the electron-hole symmetry of Landau levels\nis broken, while a double-peaked conductivity develops at low-energy, resulting\nfrom the formation of critical states conveyed by the random network of\ndefects-induced impurity states. Scaling analysis hints towards the existence\nof an additional zero-energy quantized Hall conductance plateau, which is here\nnot connected to degeneracy lifting of Landau levels by sublattice symmetry\nbreakage. This singularly contrasts with usual interpretation, and unveils a\nnew playground for tailoring the fundamental characteristics of the quantum\nHall effect."
    },
    {
        "anchor": "Giant isotope effect in the incoherent tunneling specific heat of the\n  molecular nanomagnet Fe8: Time-dependent specific heat experiments on the molecular nanomagnet Fe8 and\nthe isotopic enriched analogue 57Fe8 are presented. The inclusion of the 57Fe\nnuclear spins leads to a huge enhancement of the specific heat below 1 K,\nascribed to a strong increase in the spin-lattice relaxation rate Gamma arising\nfrom incoherent, nuclear-spin-mediated magnetic quantum tunneling in the\nground-doublet. Since Gamma is found comparable to the expected tunneling rate,\nthe latter process has to be inelastic. A model for the coupling of the\ntunneling levels to the lattice is presented. Under transverse field, a\ncrossover from nuclear-spin-mediated to phonon-induced tunneling is observed.",
        "positive": "The effect of bilayer domains on electronic transport properties of\n  epitaxial graphene on SiC: Magnetotransport measurements on Hall bar devices fabricated on purely\nmonolayer epitaxial graphene on Silicon Carbide (SiC/G) show a very tight\nspread in carrier concentration and mobility across wafer- size dimensions. In\ncontrast, SiC/G devices containing bilayer graphene domains display variations\nin their electronic properties linked to the amount of bilayer content."
    },
    {
        "anchor": "Topological properties of multilayer magnon insulators: Two-dimensional magnetic insulators can be promising hosts for topological\nmagnons. In this study, we show that ABC-stacked honeycomb lattice multilayers\nwith alternating Dzyaloshinskii-Moriya interaction (DMI) reveal a rich\ntopological magnon phase diagram. Based on our bandstructure and Berry\ncurvature calculations, we demonstrate jumps in the thermal Hall behavior that\ncorroborate with topological phase transitions triggered by adjusting the DMI\nand interlayer coupling. We connect the phase diagram of generic multilayers to\na bilayer and a trilayer system. We find an even-odd effect amongst the\nmultilayers where the even layers show no jump in thermal Hall conductivity,\nbut the odd layers do. We also observe the presence of topological proximity\neffect in our trilayer. Our results offer new schemes to manipulate Chern\nnumbers and their measurable effects in topological magnonic systems.",
        "positive": "Quantum Pumping in the Magnetic Field: Role of Discrete Symmetries: We consider an effect of the discrete spatial symmetries and magnetic field\non the adiabatic charge pumping in mesoscopic systems. In general case, there\nis no symmetry of the pumped charge with respect to the inversion of magnetic\nfield Q(B) \\neq Q(-B). We find that the reflection symmetries give rise to\nrelations Q(B)=Q(-B) or Q(B)=-Q(-B) depending on the orientation of the\nreflection axis. In presence of the center of inversion, Q(B) = 0. Additional\nsymmetries may arise in the case of bilinear pumping."
    },
    {
        "anchor": "Nonlinear conductance quantization in graphene ribbons: We present numerical studies of non-linear conduction in graphene nanoribbons\nwhen a bias potential is applied between the source and drain electrodes. We\nfind that the conductance quantization plateaus show asymmetry between the\nelectron and hole branches if the potential in the ribbon equals the source or\ndrain electrode potential and strong electron (hole) scattering occurs. The\nscattering may be at the ends of a uniform ballistic ribbon connecting wider\nregions of graphene or may be due to defects in the ribbon. We argue that, in\nribbons with strong defect scattering, the ribbon potential is pinned to that\nof the drain (source) for electron (hole) transport. In this case symmetry\nbetween electron and hole transport is restored and our calculations explain\nthe upward shift of the conductance plateaus with increasing bias that was\nobserved experimentally by Lin et al. [Phys. Rev. B 78, 161409 (2008)].",
        "positive": "Bulk Fermi surface coexistence with Dirac surface state in Bi$_2$Se$_3$:\n  a comparison of photoemission and Shubnikov-de Haas measurements: Shubnikov de Haas (SdH) oscillations and Angle Resolved PhotoEmission\nSpectroscopy (ARPES) are used to probe the Fermi surface of single crystals of\nBi2Se3. We find that SdH and ARPES probes quantitatively agree on measurements\nof the effective mass and bulk band dispersion. In high carrier density\nsamples, the two probes also agree in the exact position of the Fermi level EF,\nbut for lower carrier density samples discrepancies emerge in the position of\nEF. In particular, SdH reveals a bulk three-dimensional Fermi surface for\nsamples with carrier densities as low as 10^17cm-3. We suggest a simple\nmechanism to explain these differences and discuss consequences for existing\nand future transport studies of topological insulators."
    },
    {
        "anchor": "Quantum Interference Control of Localized Carrier Distributions in the\n  Brillouin Zone: Using transition-metal dichalcogenides as an example, we show that the\nquantum interference arising in two- and three-photon absorption processes can\nlead to controllable, highly localized carrier distributions in the Brillouin\nzone. We contrast this with the previously studied one- and two-photon\nabsorption, and find qualitatively different features, including changes in the\nrelevance of interband and intraband processes according to the excitation\nenergy. Thus, the distribution of excitations arising under certain\ncircumstances in two- and three-photon absorption can facilitate the study of\nfar-from-equilibrium states that are initially well localized in crystal\nmomentum space.",
        "positive": "Spaser and optical amplification conditions in gold-coated active\n  nanoparticles: Due to their many potential applications, there is an increasing interest in\nstudying hybrid systems composed of optically active media and plasmonic\nmetamaterials. In this work we focus on a particular system which consists of\nan optically active silica core covered by a gold shell. We find that the\nspaser (surface plasmon amplification by stimulated emission of radiation)\nconditions can be found at the poles of the scattering cross section of the\nsystem, a result that remains valid beyond the geometry studied. We explored a\nwide range of parameters that cover most of the usual experimental conditions\nin terms of the geometry of the system and the wavelength of excitation. We\nshow that the conditions of spaser generation necessarily require full loss\ncompensation, but the opposite is not necessarily true. Our results, which are\nindependent of the detailed response of the active medium, provide the gain\nneeded and the wavelength of the spasers that can be produced by a particular\ngeometry, discussing also the possibility of turning the system into optical\namplifiers and SERS (surface enhanced Raman spectroscopy) substrates with huge\nenhancements. We believe that our results can find numerous applications. In\nparticular, they can be useful for experimentalists studying similar systems in\nboth, tuning the experimental conditions and interpreting the results."
    },
    {
        "anchor": "Tuning electronic properties in graphene quantum dots by chemical\n  functionalization: Density functional theory calculations: The electronic energy gap and total dipole moment of chemically\nfunctionalized hexagonal and triangular graphene quantum dots are investigated\nby the density functional theory. It has been found that the energy gap can be\nefficiently tuned in the selected clusters by edge passivation with different\nelements or groups. Edge passivation with oxygen provides a considerable\ndecrease of the large energy gap observed in hexagonal nanodots. The edge\nstates and energy gap in triangular graphene quantum dots can also be\nmanipulated by passivation with fluorine. The total dipole moment strongly\ndepends on: (a) the shape and edge termination of the graphene quantum dot, (b)\nthe attached group, and (c) the position to which the groups are attached. With\nrespect to the shape, edge termination, and the attached group the chemically\nmodified hexagonal-armchair quantum dot has the highest total dipole moment.\nDepending on the position of the attached groups, the total dipole can be\nincreased, decreased, or eliminated. The significant features, the tunable\nenergy gap and total dipole moment, of the functionalized graphene quantum dots\nare confirmed by the stability calculations. The obtained positive binding\nenergy and positive frequencies in the infrared spectra imply that all the\nselected clusters are stable under edge functionalization and passivation with\nvarious groups and elements.",
        "positive": "Entangled photons on demand: Erasing which-path information with\n  sidebands: The biexciton cascade in a quantum dot can be used to generate\nentangled-photon pairs rapidly and deterministically (on demand). However, due\nto a large fine-structure splitting between intermediate exciton energy levels,\nwhich-path information encoded in the frequencies of emitted photon pairs leads\nto a small degree of entanglement. Here we show that this information can be\nefficiently erased by modulating the exciton and biexciton energy levels,\ngiving rise to new decay paths through additional sidebands. The resulting\ndegree of entanglement is substantial, and can be made maximal through spectral\nfiltering, with only a nominal reduction in collection efficiency."
    },
    {
        "anchor": "Scanning Tunneling Microscopy Study and Nanomanipulation of\n  Graphene-Coated Water on Mica: We study interfacial water trapped between a sheet of graphene and a\nmuscovite (mica) surface using Raman spectroscopy and ultra-high vacuum\nscanning tunneling microscopy (UHV-STM) at room temperature. We are able to\nimage the graphene-water interface with atomic resolution, revealing a layered\nnetwork of water trapped underneath the graphene. We identify water layer\nnumbers with a carbon nanotube height reference. Under normal scanning\nconditions, the water structures remain stable. However, at greater electron\nenergies, we are able to locally manipulate the water using the STM tip.",
        "positive": "Formation of buried conductive micro-channels in single crystal diamond\n  with MeV C and He implantation: As demonstrated in previous works, implantation with a MeV ion microbeam\nthrough masks with graded thickness allows the formation of conductive\nmicro-channels in diamond which are embedded in the insulating matrix at\ncontrollable depths [P. Olivero et al., Diamond Relat. Mater. 18 (5-8), 870-876\n(2009)]. In the present work we report about the systematic electrical\ncharacterization of such micro-channels as a function of several implantation\nconditions, namely: ion species and energy, implantation fluence. The\ncurrent-voltage (IV) characteristics of the buried channels were measured at\nroom temperature with a two point probe station. Significant parameters such as\nthe sheet resistance and the characteristic exponent (alpha) of the IV\npower-law trend were expressed as a function of damage density, with\nsatisfactory compatibility between the results obtained in different\nimplantation conditions."
    },
    {
        "anchor": "Edge mode velocities in the quantum Hall effect from a dc measurement: Because of the bulk gap, low energy physics in the quantum Hall effect is\nconfined to the edges of the 2D electron liquid. The velocities of edge modes\nare key parameters of edge physics. They were determined in several quantum\nHall systems from time-resolved measurements and high-frequency ac transport.\nWe propose a way to extract edge velocities from dc transport in a point\ncontact geometry defined by narrow gates. The width of the gates assumes two\ndifferent sizes at small and large distances from the point contact. The\nCoulomb interaction across the gates depends on the gate width and affects the\nconductance of the contact. The conductance exhibits two different temperature\ndependencies at high and low temperatures. The transition between the two\nregimes is determined by the edge velocity. An interesting feature of the\nlow-temperature I-V curve is current oscillations as a function of the voltage.\nThe oscillations emerge due to charge reflection from the interface of the\nregions defined by the narrow and wide sections of the gates.",
        "positive": "Anisotropic intrinsic spin Hall effect in quantum wires: We use numerical simulations to investigate the spin Hall effect in quantum\nwires in the presence of both Rashba and Dresselhaus spin-orbit coupling. We\nfind that the intrinsic spin Hall effect is highly anisotropic with respect to\nthe orientation of the wire, and that the nature of this anisotropy depends\nstrongly on the electron density and the relative strengths of the Rashba and\nDresselhaus spin-orbit coupling. In particular, at low densities when only one\nsubband of the quantum wire is occupied, the spin Hall effect is strongest for\nelectron momentum along the $[\\bar{1}10]$ axis, which is opposite than what is\nexpected for the purely 2D case. In addition, when more than one subband is\noccupied, the strength and anisotropy of the spin Hall effect can vary greatly\nover relatively small changes in electron density, which makes it difficult to\npredict which wire orientation will maximize the strength of the spin Hall\neffect. These results help to illuminate the role of quantum confinement in\nspin-orbit-coupled systems, and can serve as a guide for future experimental\nwork on the use of quantum wires for spin-Hall-based spintronic applications."
    },
    {
        "anchor": "Electronic spin working mechanically: A single-electron tunneling (SET) device with a nanoscale central island that\ncan move with respect to the bulk source- and drain electrodes allows for a\nnanoelectromechanical (NEM) coupling between the electrical current through the\ndevice and mechanical vibrations of the island. Although an electromechanical\n\"shuttle\" instability and the associated phenomenon of single-electron\nshuttling were predicted more than 15 years ago, both theoretical and\nexperimental studies of NEM-SET structures are still carried out. New\nfunctionalities based on quantum coherence, Coulomb correlations and coherent\nelectron-spin dynamics are of particular current interest. In this article we\npresent a short review of recent activities in this area.",
        "positive": "Relativistic graphene ratchet on semidisk Galton board: Using extensive Monte Carlo simulations we study numerically and analytically\na photogalvanic effect, or ratchet, of directed electron transport induced by a\nmicrowave radiation on a semidisk Galton board of antidots in graphene. A\ncomparison between usual two-dimensional electron gas (2DEG) and electrons in\ngraphene shows that ratchet currents are comparable at very low temperatures.\nHowever, a large mean free path in graphene should allow to have a strong\nratchet transport at room temperatures. Also in graphene the ratchet transport\nemerges even for unpolarized radiation. These properties open promising\npossibilities for room temperature graphene based sensitive photogalvanic\ndetectors of microwave and terahertz radiation."
    },
    {
        "anchor": "Strong gate coupling of high-Q nanomechanical resonators: The detection of mechanical vibrations near the quantum limit is a formidable\nchallenge since the displacement becomes vanishingly small when the number of\nphonon quanta tends towards zero. An interesting setup for on-chip\nnanomechanical resonators is that of coupling them to electrical microwave\ncavities for detection and manipulation. Here we show how to achieve a large\ncavity coupling energy of up to (2 \\pi) 1 MHz/nm for metallic beam resonators\nat tens of MHz. We used focused ion beam (FIB) cutting to produce uniform slits\ndown to 10 nm, separating patterned resonators from their gate electrodes, in\nsuspended aluminum films. We measured the thermomechanical vibrations down to a\ntemperature of 25 mK, and we obtained a low number of about twenty phonons at\nthe equilibrium bath temperature. The mechanical properties of Al were\nexcellent after FIB cutting and we recorded a quality factor of Q ~ 3 x 10^5\nfor a 67 MHz resonator at a temperature of 25 mK. Between 0.2K and 2K we find\nthat the dissipation is linearly proportional to the temperature.",
        "positive": "Spin-Orbit induced semiconductor spin guides: The tunability of the Rashba spin-orbit coupling allows to build\nsemiconductor heterostructures with space modulated coupling intensities. We\nshow that a wire-shaped spin-orbit modulation in a quantum well can support\npropagating electronic states inside the wire only for a certain spin\norientation and, therefore, it acts as an effective spin transmission guide for\nthis particular spin orientation."
    },
    {
        "anchor": "Conductance of Open Quantum Billiards and Classical Trajectories: We analyse the transport phenomena of 2D quantum billiards with convex\nboundary of different shape. The quantum mechanical analysis is performed by\nmeans of the poles of the S-matrix while the classical analysis is based on the\nmotion of a free particle inside the cavity along trajectories with a different\nnumber of bounces at the boundary. The value of the conductance depends on the\nmanner the leads are attached to the cavity. The Fourier transform of the\ntransmission amplitudes is compared with the length of the classical paths.\nThere is good agreement between classical and quantum mechanical results when\nthe conductance is achieved mainly by special short-lived states such as\nwhispering gallery modes (WGM) and bouncing ball modes (BBM). In these cases,\nalso the localization of the wave functions agrees with the picture of the\nclassical paths. The S-matrix is calculated classically and compared with the\ntransmission coefficients of the quantum mechanical calculations for five modes\nin each lead. The number of modes coupled to the special states is effectively\nreduced.",
        "positive": "Majorana coupling and Kondo screening of localized spins: We perform a theoretical analysis of the fate of local magnetic moment of a\nquantum dot coupled to a normal metallic lead and a topological superconducting\nwire hosting Majorana modes at the ends. By means of simple analytical tools\nand numerical renormalization group calculations we show that the proximity of\nMajorana mode reduces the magnetic moment from $1/4$, characteristic of a free\nspin $1/2$, to $1/16$. The coupling to the normal lead then causes the Kondo\neffect, such that the magnetic moment is fully screened below the Kondo\ntemperature. The latter is vastly increased for strong coupling to Majorana\nmode."
    },
    {
        "anchor": "Dirac Cones, Topological Edge States, and Nontrivial Flat Bands in\n  Two-Dimensional Semiconductors with a Honeycomb Nanogeometry: We study theoretically two-dimensional single-crystalline sheets of\nsemiconductors that form a honeycomb lattice with a period below 10 nm. These\nsystems could combine the usual semiconductor properties with Dirac bands.\nUsing atomistic tight-binding calculations, we show that both the atomic\nlattice and the overall geometry influence the band structure, revealing\nmaterials with unusual electronic properties. In rocksalt Pb chalcogenides, the\nexpected Dirac-type features are clouded by a complex band structure. However,\nin the case of zinc-blende Cd-chalcogenide semiconductors, the honeycomb\nnanogeometry leads to rich band structures, including, in the conduction band,\nDirac cones at two distinct energies and nontrivial flat bands and, in the\nvalence band, topological edge states. These edge states are present in several\nelectronic gaps opened in the valence band by the spin-orbit coupling and the\nquantum confinement in the honeycomb geometry. The lowest Dirac conduction band\nhas S-orbital character and is equivalent to the pi-pi* band of graphene but\nwith renormalized couplings. The conduction bands higher in energy have no\ncounterpart in graphene; they combine a Dirac cone and flat bands because of\ntheir P-orbital character. We show that the width of the Dirac bands varies\nbetween tens and hundreds of meV. These systems emerge as remarkable platforms\nfor studying complex electronic phases starting from conventional\nsemiconductors. Recent advancements in colloidal chemistry indicate that these\nmaterials can be synthesized from semiconductor nanocrystals.",
        "positive": "Quasiparticle bandgap engineering of graphene and graphone on hexagonal\n  boron nitride substrate: Graphene holds great promise for post-silicon electronics, however, it faces\ntwo main challenges: opening up a bandgap and finding a suitable substrate\nmaterial. In principle, graphene on hexagonal boron nitride (hBN) substrate\nprovides potential system to overcome these challenges. Recent theoretical and\nexperimental studies have provided conflicting results: while theoretical\nstudies suggested a possibility of a finite bandgap of graphene on hBN, recent\nexperimental studies find no bandgap. Using the first-principles density\nfunctional method and the many-body perturbation theory, we have studied\ngraphene on hBN substrate. A Bernal stacked graphene on hBN has a bandgap on\nthe order of 0.1 eV, which disappears when graphene is misaligned with respect\nto hBN. The latter is the likely scenario in realistic devices. In contrast, if\ngraphene supported on hBN is hydrogenated, the resulting system (graphone)\nexhibits bandgaps larger than 2.5 eV. While the bandgap opening in graphene/hBN\nis due to symmetry breaking and is vulnerable to slight perturbation such as\nmisalignment, the graphone bandgap is due to chemical functionalization and is\nrobust in the presence of misalignment. The bandgap of graphone reduces by\nabout 1 eV when it is supported on hBN due to the polarization effects at the\ngraphone/hBN interface. The band offsets at graphone/hBN interface indicate\nthat hBN can be used not only as a substrate but also as a dielectric in the\nfield effect devices employing graphone as a channel material. Our study could\nopen up new way of bandgap engineering in graphene based nanostructures."
    },
    {
        "anchor": "Magnetic skyrmion generation by reflective spin-wave focusing: We propose a method to generate magnetic skyrmions by focusing spin waves\ntotally reflected by a curved film edge. Based on the principle of identical\nmagnonic path length, we derive the edge contour that is parabolic and\nfrequency-independent. Micromagnetic simulations are performed to verify our\ntheoretical design. It is found that under proper conditions, magnetic droplet\nfirst emerges near the focal point where the spin-wave intensity has been\nsignificantly enhanced, and then converts to magnetic skyrmion accompanied by a\nchange of the topological charge. The phase diagram about the amplitude and\nfrequency of the driving field for skyrmion generation is obtained. Our finding\nwould be helpful for the designment of spintronic devices combing the advantage\nof skyrmionics and magnonics.",
        "positive": "Hybrid Quantum Dot-2D Electron Gas Devices for Coherent Optoelectronics: We present an inverted GaAs 2D electron gas with self-assembled InAs quantum\ndots in close proximity, with the goal of combining quantum transport with\nquantum optics experiments. We have grown and characterized several wafers --\nusing transport, AFM and optics -- finding narrow-linewidth optical dots and\nhigh-mobility, single subband 2D gases. Despite being buried 500 nm below the\nsurface, the dots are clearly visible on AFM scans, allowing precise\nlocalization and paving the way towards a hybrid quantum system integrating\noptical dots with surface gate-defined nanostructures in the 2D gas."
    },
    {
        "anchor": "Spin Hall Drag: We predict a new effect in electronic bilayers: the {\\it Spin Hall Drag}. The\neffect consists in the generation of spin accumulation across one layer by an\nelectric current along the other layer. It arises from the combined action of\nspin-orbit and Coulomb interactions. Our theoretical analysis, based on the\nBoltzmann equation formalism, identifies two main contributions to the spin\nHall drag resistivity: the side-jump contribution, which dominates at low\ntemperature, going as $T^2$, and the skew-scattering contribution, which is\nproportional to $T^3$. The induced spin accumulation is large enough to be\ndetected in optical rotation experiments.",
        "positive": "Experimental signature of a topological quantum dot: Topological insulators (TIs) present a neoteric class of materials, which\nsupport delocalised, conducting surface states despite an insulating bulk. Due\nto their intriguing electronic properties, their optical properties have\nreceived relatively less attention. Even less well studied is their behaviour\nin the nanoregime, with most studies thus far focusing on bulk samples - in\npart due to the technical challenges of synthesizing TI nanostructures. We\nstudy topological insulator nanoparticles (TINPs), for which quantum effects\ndominate the behaviour of the surface states and quantum confinement results in\na discretized Dirac cone, whose energy levels can be tuned with the\nnanoparticle size. The presence of these discretized energy levels in turn\nleads to a new electron-mediated phonon-light coupling in the THz range. We\npresent the experimental realisation of Bi$_2$Te$_3$ TINPs and strong evidence\nof this new quantum phenomenon, remarkably observed at room temperature. This\nsystem can be considered a topological quantum dot, with applications to room\ntemperature THz quantum optics and quantum information technologies."
    },
    {
        "anchor": "Helical trilayer graphene: a moir\u00e9 platform for strongly-interacting\n  topological bands: Quantum geometry of electronic wavefunctions results in fascinating\ntopological phenomena. A prominent example is the intrinsic anomalous Hall\neffect (AHE) in which a Hall voltage arises in the absence of an applied\nmagnetic field. The AHE requires a coexistence of Berry curvature and\nspontaneous time-reversal symmetry breaking. These conditions can be realized\nin two-dimensional moir\\'e systems with broken $xy$-inversion symmetry\n($C_{2z}$) that host flat electronic bands. Here, we explore helical trilayer\ngraphene (HTG), three graphene layers twisted sequentially by the same angle\nforming two misoriented moir\\'e patterns. Although HTG is globally\n$C_{2z}$-symmetric, surprisingly we observe clear signatures of topological\nbands. At a magic angle $\\theta_\\mathrm{m}\\approx 1.8^\\circ$, we uncover a\nrobust phase diagram of correlated and magnetic states using magnetotransport\nmeasurements. Lattice relaxation leads to large periodic domains in which\n$C_{2z}$ is broken on the moir\\'e scale. Each domain harbors flat topological\nbands with valley-contrasting Chern numbers $\\pm(1,-2)$. We find correlated\nstates at integer electron fillings per moir\\'e unit cell $\\nu=1,2,3$ and\nfractional fillings $2/3,7/2$ with the AHE arising at $\\nu=1,3$ and $2/3,7/2$.\nAt $\\nu=1$, a time-reversal symmetric phase appears beyond a critical electric\ndisplacement field, indicating a topological phase transition. Finally,\nhysteresis upon sweeping $\\nu$ points to first-order phase transitions across a\nspatial mosaic of Chern domains separated by a network of topological gapless\nedge states. We establish HTG as an important platform that realizes ideal\nconditions for exploring strongly interacting topological phases and, due to\nits emergent moir\\'e-scale symmetries, demonstrates a novel way to engineer\ntopology.",
        "positive": "Probing the Nature of Defects in Graphene by Raman Spectroscopy: Raman Spectroscopy is able to probe disorder in graphene through\ndefect-activated peaks. It is of great interest to link these features to the\nnature of disorder. Here we present a detailed analysis of the Raman spectra of\ngraphene containing different type of defects. We found that the intensity\nratio of the D and D' peak is maximum (~ 13) for sp3-defects, it decreases for\nvacancy-like defects (~ 7) and reaches a minimum for boundaries in graphite\n(~3.5)."
    },
    {
        "anchor": "Phonon Squeezed States: Quantum Noise Reduction in Solids: This article discusses quantum fluctuation properties of a crystal lattice,\nand in particular, phonon squeezed states. Squeezed states of phonons allow a\nreduction in the quantum fluctuations of the atomic displacements to below the\nzero-point quantum noise level of coherent phonon states. Here we discuss our\nstudies of both continuous-wave and impulsive second-order Raman scattering\nmechanisms. The later approach was used to experimentally suppress (by one part\nin a million only, which might be noise) fluctuations in phonons (and it has\nnot been clearly reproduced by other experimental groups). We calculate the\nexpectation values and fluctuations of both the atomic displacement and the\nlattice amplitude operators, as well as the effects of the phonon squeezed\nstates on macroscopically measurable quantities, such as changes in the\ndielectric constant. These results are compared with recent experiments.\nFurther information, including preprints and animations, are available in\nhttp://www-personal.engin.umich.edu/\\~nori/squeezed.html",
        "positive": "Statistics of reflection eigenvalues in chaotic cavities with non-ideal\n  leads: The scattering matrix approach is employed to determine a joint probability\ndensity function of reflection eigenvalues for chaotic cavities coupled to the\noutside world through both ballistic and tunnel point contacts. Derived under\nassumption of broken time-reversal symmetry, this result is further utilised to\n(i) calculate the density and correlation functions of reflection eigenvalues,\nand (ii) analyse fluctuations properties of the Landauer conductance for the\nillustrative example of asymmetric chaotic cavity. Further extensions of the\ntheory are pinpointed."
    },
    {
        "anchor": "Exact-Diagonalization Studies of Inelastic Light Scattering in\n  Self-Assembled Quantum Dots: We report exact diagonalization studies of inelastic light scattering in\nfew-electron quantum dots under the strong confinement regime characteristic of\nself-assembled dots. We apply the orthodox (second-order) theory for scattering\ndue to electronic excitations, leaving for the future the consideration of\nhigher-order effects in the formalism (phonons, for example), which seem\nrelevant in the theoretical description of available experiments. Our numerical\nresults stress the dominance of monopole peaks in Raman spectra and the\nbreakdown of selection rules in open-shell dots. The dependence of these\nspectra on the number of electrons in the dot and the incident photon energy is\nexplicitly shown. Qualitative comparisons are made with recent experimental\nresults.",
        "positive": "Iodine versus Bromine Functionalization for Bottom-Up Graphene\n  Nanoribbon Growth: Role of Diffusion: Deterministic bottom-up approaches for synthesizing atomically well-defined\ngraphene nanoribbons (GNRs) largely rely on the surface-catalyzed activation of\nselected labile bonds in a molecular precursor followed by step growth\npolymerization and cyclodehydrogenation. While the majority of successful GNR\nprecursors rely on the homolytic cleavage of thermally labile C-Br bonds, the\nintroduction of weaker C-I bonds provides access to monomers that can be\npolymerized at significantly lower temperatures, thus helping to increase the\nflexibility of the GNR synthesis process. Scanning tunneling microscopy (STM)\nimaging of molecular precursors, activated intermediates, and polymers\nresulting from stepwise thermal annealing of both Br and I substituted\nprecursors for chevron GNRs reveals that the polymerization of both precursors\nproceeds at similar temperatures on Au(111). This observation is consistent\nwith diffusion-limited polymerization of the surface-stabilized radical\nintermediates that emerge from homolytic cleavage of either the C-Br or the C-I\nbonds."
    },
    {
        "anchor": "Defect-Free Carbon Nanotube Coils: Carbon nanotubes are promising building blocks for various nanoelectronic\ncomponents. A highly desirable geometry for such applications is a coil.\nHowever, coiled nanotube structures reported so far were inherently defective\nor had no free ends accessible for contacting. Here we demonstrate the\nspontaneous self-coiling of single-wall carbon nanotubes into defect-free coils\nof up to more than 70 turns with identical diameter and chirality, and free\nends. We characterize the structure, formation mechanism, and electrical\nproperties of these coils by different microscopies, molecular dynamics\nsimulations, Raman spectroscopy, and electrical and magnetic measurements. The\ncoils are highly conductive, as expected for defect-free carbon nanotubes, but\nadjacent nanotube segments in the coil are more highly coupled than in regular\nbundles of single-wall carbon nanotubes, owing to their perfect crystal\nmomentum matching, which enables tunneling between the turns. Although this\nbehavior does not yet enable the performance of these nanotube coils as\ninductive devices, it does point a clear path for their realization. Hence,\nthis study represents a major step toward the production of many different\nnanotube coil devices, including inductors, electromagnets, transformers, and\ndynamos.",
        "positive": "Supercell symmetry modified spectral statistics of Kramers-Weyl fermions: We calculate the spectral statistics of the Kramers-Weyl Hamiltonian\n$H=v\\sum_{\\alpha} \\sigma_\\alpha\\sin p_\\alpha+t \\sigma_0\\sum_\\alpha\\cos\np_\\alpha$ in a chaotic quantum dot. The Hamiltonian has symplectic\ntime-reversal symmetry ($H$ is invariant when spin $\\sigma_\\alpha$ and momentum\n$p_\\alpha$ both change sign), and yet for small $t$ the level spacing\ndistribution $P(s)\\propto s^\\beta$ follows the $\\beta=1$ orthogonal ensemble\ninstead of the $\\beta=4$ symplectic ensemble. We identify a supercell symmetry\nof $H$ that explains this finding. The supercell symmetry is broken by the\nspin-independent hopping energy $\\propto t\\cos p$, which induces a transition\nfrom $\\beta=1$ to $\\beta=4$ statistics that shows up in the conductance as a\ntransition from weak localization to weak antilocalization."
    },
    {
        "anchor": "High-quality single InGaAs/GaAs quantum dot growth on a CMOS-compatible\n  silicon substrate for quantum photonic applications: We present the direct heteroepitaxial growth of high-quality InGaAs quantum\ndots on silicon, enabling scalable, cost-effective quantum photonics devices\ncompatible with CMOS technology. GaAs heterostructures are grown on silicon via\na GaP buffer and defect-reducing layers. These epitaxial quantum dots exhibit\noptical properties akin to those on traditional GaAs substrates, promising vast\npotential for the heteroepitaxy approach. They demonstrate strong multi-photon\nsuppression with $g^{(2)}(\\tau)=(3.7\\pm 0.2) \\times 10^{-2}$ and high photon\nindistinguishability $V=(66\\pm 19)$% under non-resonance excitation. We achieve\nup to ($18\\pm 1$)% photon extraction efficiency with a backside distributed\nBragg mirror, marking a crucial step toward silicon-based quantum\nnanophotonics.",
        "positive": "Characterization of spin wave propagation in (111) YIG thin films with\n  large anisotropy: We report on long-range spin wave (SW) propagation in nanometer-thick yttrium\niron garnet (YIG) film with an ultralow Gilbert damping. The knowledge of a\nwavenumber value $|\\vec{k}|$ is essential for designing SW devices. Although\ndetermining the wavenumber $|\\vec{k}|$ in experiments like Brillouin light\nscattering spectroscopy is straightforward, quantifying the wavenumber in\nall-electrical experiments has not been widely commented upon so far. We\nanalyze magnetostatic spin wave (SW) propagation in YIG films in order to\ndetermine the SW wavenumber $|\\vec{k}|$ excited by the coplanar waveguide. We\nshow that it is crucial to consider the influence of magnetic anisotropy fields\npresent in YIG thin films for precise determination of SW wavenumber. With the\nproposed methods we find that experimentally derived values of $|\\vec{k}|$ are\nin perfect agreement with that obtained from electromagnetic simulation only if\nanisotropy fields are included."
    },
    {
        "anchor": "Optimal trap shape for a Bose gas with attractive interactions: Dilute Bose gas with attractive interactions is considered at zero\ntemperature, when practically all atoms are in Bose-Einstein condensate. The\nproblem is addressed aiming at answering the question: What is the optimal trap\nshape allowing for the condensation of the maximal number of atoms with\nnegative scattering lengths? Simple and accurate analytical formulas are\nderived allowing for an easy analysis of the optimal trap shapes. These\nanalytical formulas are the main result of the paper.",
        "positive": "Thermoelectric effect in a parallel double quantum dot structure: We discuss the thermoelectric properties assisted by the Fano effect of a\nparallel double quantum dot (QD) structure. By adjusting the couplings between\nthe QDs and leads, we facilitate the nonresonant and resonant channels for the\nFano interference. It is found that at low temperature, Fano lineshapes appear\nin the electronic and thermal conductance spectra, which can also be reversed\nby an applied local magnetic flux with its phase factor $\\phi=\\pi$. And, the\nFano effect contributes decisively to the enhancement of thermoelectric\nefficiency. However, at the same temperature, the thermoelectric effect in the\ncase of $\\phi=\\pi$ is much more apparent, compared with the case of zero\nmagnetic flux. By the concept of Feynman path, we analyze the difference\nbetween the quantum interferences in the cases of $\\phi=0$ and $\\phi=\\pi$. It\nis seen that in the absence of magnetic flux the Fano interference originates\nfrom the quantum interference among infinite-order Feynman paths, but it occurs\nonly between two lowest-order Feynman paths when $\\phi=\\pi$. The increase of\ntemperature inevitably destroys the electron coherent transmission in each\npaths. So, in the case of zero magnetic field, the thermoelectric effect\ncontributed by the Fano interference is easy to weaken by a little increase of\ntemperature."
    },
    {
        "anchor": "Topological insulators beyond the Brillouin zone via Chern parity: The topological insulator is an electronic phase stabilized by spin-orbit\ncoupling that supports propagating edge states and is not adiabatically\nconnected to the ordinary insulator. In several ways it is a spin-orbit-induced\nanalogue in time-reversal-invariant systems of the integer quantum Hall effect\n(IQHE). This paper studies the topological insulator phase in disordered\ntwo-dimensional systems, using a model graphene Hamiltonian introduced by Kane\nand Mele as an example. The nonperturbative definition of a topological\ninsulator given here is distinct from previous efforts in that it involves\nboundary phase twists that couple only to charge, does not refer to edge\nstates, and can be measured by pumping cycles of ordinary charge. In this\ndefinition, the phase of a Slater determinant of electronic states is\ndetermined by a Chern parity analogous to Chern number in the IQHE case.\nNumerically we find, in agreement with recent network model studies, that the\ndirect transition between ordinary and topological insulators that occurs in\nband structures is a consequence of the perfect crystalline lattice.\nGenerically these two phases are separated by a metallic phase, which is\nallowed in two dimensions when spin-orbit coupling is present. The same\napproach can be used to study three-dimensional topological insulators.",
        "positive": "Three stage decoherence dynamics of electron spin qubits in an optically\n  active quantum dot: The control of discrete quantum states in solids and their use for quantum\ninformation processing is complicated by the lack of a detailed understanding\nof the mechanisms responsible for qubit decoherences. For spin qubits in\nsemiconductor quantum dots, phenomenological models of decoherence currently\nrecognize two Basic stages; fast ensemble dephasing due to the coherent\nprecession of spin qubits around nearly static but randomly distributed\nhyperfine fields and a much slower process of irreversible relaxation of spin\nqubit polarization due to dynamics of the nuclear spin bath induced by complex\nmany-body interaction effects. We unambiguosly demonstrate that such a view on\ndecoherence is greatly oversimplified; the relaxation of a spin qubit state is\ndetermined by three rather than two basic stages. The additional stage\ncorresponds to the effect of coherent dephasing processes that occur in the\nnuclear spin bath that manifests itself by a relatively fast but incomplete\nnon-monotonous relaxation of the central spin polarization at intermediate\ntimescales. This observation changes our understanding of the electron spin\nqubit decoherence mechanisms in solid state systems."
    },
    {
        "anchor": "Doppler velocimetry of spin propagation in a two-dimensional electron\n  gas: Controlling the flow of electrons by manipulation of their spin is a key to\nthe development of spin-based electronics. While recent demonstrations of\nelectrical-gate control in spin-transistor configurations show great promise,\noperation at room temperature remains elusive. Further progress requires a\ndeeper understanding of the propagation of spin polarization, particularly in\nthe high mobility semiconductors used for devices. Here we report the\napplication of Doppler velocimetry to resolve the motion of spin-polarized\nelectrons in GaAs quantum wells driven by a drifting Fermi sea. We find that\nthe spin mobility tracks the high electron mobility precisely as a function of\nT. However, we also observe that the coherent precession of spins driven by\nspin-orbit interaction, which is essential for the operation of a broad class\nof spin logic devices, breaks down at temperatures above 150 K for reasons that\nare not understood theoretically.",
        "positive": "Ferromagnetic barrier induced negative differential conductance on the\n  surface of a topological insulator: We theoretically investigate the effect of the negative differential\nconductance of a ferromagnetic barrier on the surface of a topological\ninsulator. Due to the changes of the shape and position of the Fermi surfaces\nin the ferromagnetic barrier, the transport processes can be divided into three\nkinds: the total, partial and blockade transmission mechanisms. The bias\nvoltage can give rise to the transition of the transport processes from partial\nto blockade transmission mechanisms, which results in a giant effect of\nnegative differential conductance. With appropriate structural parameters, the\ncurrent-voltage characteristics show that the minimum value of the current can\nreach to zero in a wide range of the bias voltage, and a large peak-to-valley\ncurrent ratio can be obtained."
    },
    {
        "anchor": "Ultrafast unbalanced electron distributions in quasicrystalline 30\u00b0\n  twisted bilayer graphene: Layers of twisted bilayer graphene exhibit varieties of exotic quantum\nphenomena1-5. Today, the twist angle {\\Theta} has become an important degree of\nfreedom for exploring novel states of matters, i.e. two-dimensional\nsuperconductivity ( {\\Theta} = 1.1{\\deg})6, 7 and a two-dimensional\nquasicrystal ({\\Theta} = 30{\\deg})8, 9. We report herein experimental\nobservation on the photo-induced ultrafast dynamics of Dirac fermions in the\nquasicrystalline 30{\\deg} twisted bilayer graphene (QCTBG). We discover that\nhot carriers are asymmetrically distributed between the two graphene layers,\nfollowed by the opposing femtosecond relaxations, by using time- and\nangle-resolved photoemission spectroscopy. The key mechanism involves the\ndiffering carrier transport between layers and the transient doping from the\nsubstrate interface. The ultrafast dynamics scheme continues after the Umklapp\nscattering, which is induced by the incommensurate interlayer stacking of the\nquasi-crystallinity. The dynamics in the atomic layer opens the possibility of\nnew applications and creates interdisciplinary links in the optoelectronics of\nvan der Waals crystals.",
        "positive": "Relationship between blocking temperature and strength of interparticle\n  interaction in magnetic nanoparticle systems: In magnetic nanoparticle systems, the variation of the blocking temperature\n$T_B$ with the measuring frequency $f_m$ is often used to determine the\nstrength of the interparticle interactions (IPI) through a parameter $\\Phi$ or\nthe Vogel-Fulcher temperature $T_o$. Presence of IPI is inferred if $T_o$$>$0\nand $\\Phi=$$\\Delta$$T_B$$/$$[T_B\\Delta$$log_{10}$$f_m]<$0.13 where $\\Delta$\nsignifies changes in $T_B$ and $f_m$. Here it is shown that these two\nparameters are related by the Eq. $\\Phi=$$\\Phi_o$$\\approx$ 0.11 to 0.15 is a\nconstant of the system depending on the magnitudes of measuring frequency and\n$\\Phi=$$\\Phi_o$$[1-T_o/T_B]$ where the attempt frequency $f_o$ of the N\\'eel\nrelaxation. Experimental verification of this relationship is also presented\nusing data on a variety of nanoparticle systems."
    },
    {
        "anchor": "Proximity induced spin-valley polarization in silicene/germanene on\n  F-doped WS$_2$: Silicene and germanene are key materials for the field of valleytronics.\nHowever, interaction with the substrate, which is necessary to support the\nelectronically active medium, becomes a major obstacle. In the present work, we\npropose a substrate (F-doped WS$_2$) that avoids detrimental effects and at the\nsame time induces the required valley polarization, so that no further steps\nare needed for this purpose. The behavior is explained by proximity effects on\nsilicene/germanene, as demonstrated by first-principles calculations. Broken\ninversion symmetry due to the presence of WS$_2$ opens a substantial band gap\nin silicene/germanene. F doping of WS$_2$ results in spin polarization, which,\nin conjunction with proximity-enhanced spin orbit coupling, creates sizable\nspin-valley polarization.",
        "positive": "Non-Hermitian tuned topological band gap: Externally controllable band gap properties of a material is crucial in\ndesigning optoelectronic devices with desirable properties on-demand. Here, a\npossibility of single parameter tuning of trivial to non-trivial topological\nband gap by the introduction of linear gain in an otherwise trivial insulator\nis investigated. Gain is selectively injected into a one dimensional lattice of\ndimers such that the resulting non-Hermitian Hamiltonian is symmetric under\nspace-inversion but not under time-reversal. Inversion-symmetry of the lattice\nrenders to probe the bulk-boundary correspondence and topological invariance by\nthe bi-orthogonal Zak phase associated with a bulk Hamiltonian. Topological\ntrivial to nontrivial phase transition and emergence of protected edge states\nare analytically shown to occur when the gain parameter is tuned across a\nnon-Hermitian degeneracy. Tuneability of edge state location both at the\nboundary and inside the bulk by altering the gain distribution is discussed.\nConfirmation of gain-controlled topological edge state is reported in a\nrealistic design of InGaAsP semiconductor cavity array."
    },
    {
        "anchor": "Spin relaxation through Kondo scattering in Cu/Py lateral spin valves: The temperature dependence of the spin diffusion length typically reflects\nthe scattering mechanism responsible for spin relaxation. Within non-magnetic\nmetals it is reasonable to expect the Elliot-Yafet mechanism to play a role and\nthus the temperature dependence of the spin diffusion length might be inversely\nproportional to resistivity. In lateral spin valves measurements have found\nthat at low temperatures the spin diffusion length unexpected decreases. By\nmeasuring the transport properties of lateral Py/Cu/Py spin valves fabricated\nwith different purities of Cu, we extract a spin diffusion length which shows\nthis suppression below 30K only in the presence of the Kondo effect. We have\ncalculated the spin-relaxation rate and isolated the contributions from\nmagnetic impurities. We find the spin-flip probability of a magnetic impurity\nto be 34%. Our semi-quantitative analysis demonstrates the dominant role of\nKondo scattering in spin relaxation, even in low concentrations of order 1\np.p.m., and hence accounts for the reduction in spin diffusion length observed\nby ourselves and others.",
        "positive": "Atomic configuration controlled photocurrent in van der Waals\n  homostructures: Conventional photocurrents at a p-n junction depend on macroscopic built-in\nfields and are typically insensitive to the microscopic details of a crystal's\natomic configuration. Here we demonstrate how atomic configuration can control\nphotocurrent in van der Waals (vdW) materials. In particular, we find bulk\nshift photocurrents (SPC) can display a rich (atomic) configuration dependent\nphenomenology that range from contrasting SPC currents for different stacking\narrangements in a vdW homostructure (e.g., AB vs BA stacking) to a strong light\npolarization dependence for SPC that align with crystallographic axes.\nStrikingly, we find that SPC in vdW homostructures can be directed by modest\nstrain, yielding sizeable photocurrent magnitudes under unpolarized light\nirradiation and manifesting even in the absence of p-n junctions. These\ndemonstrate that SPC are intimately linked to how the Bloch wavefunctions are\nembedded in real space, and enables a new macroscopic transport probe\n(photocurrent) of lattice-scale registration in vdW materials."
    },
    {
        "anchor": "Radiation Modulated Spin coupling in DNA: The spin activity in macromolecules such as DNA and oligopeptides, in the\ncontext of the Chiral Induced Spin Selectivity (CISS) has been proposed to be\ndue to the atomic Spin-Orbit Coupling (SOC) and the associated chiral symmetry\nof the structures. This coupling, associated with carbon, nitrogen and oxygen\natoms in biological molecules, albeit small (meV), can be enhanced by the\ngeometry, and strong local polarization effects such as hydrogen bonding (HB).\nA novel way to manipulate the spin degree of freedom is by modifying the\nspectrum using a coupling to the appropriate electromagnetic radiation field.\nHere we use the Floquet formalism in order to show how the half filled band\nHamiltonian for DNA, can be modulated by the radiation to produce a up to a\ntenfold increase of the effective SOC once the intrinsic coupling is present.\nOn the other hand, the chiral model, once incorporating the orbital angular\nmomentum of electron motion on the helix, opens a gap for different helicity\nstates (helicity splitting) that chooses spin polarization according to\ntransport direction and chirality, without breaking time reversal symmetry. The\nobserved effects are feasible in physically reasonable parameter ranges for the\nradiation field amplitude and frequency.",
        "positive": "Dispersions of multi-walled carbon nanotubes in liquid crystals: new\n  challenges to molecular theories of anisotropic soft matter: Aggregation of carbon nanotubes dispersed in nematic liquid crystalline\nmedium is discussed. A model is proposed, which assumes that the aggregates\nconsist of a \"skeleton\" formed by stochastically arranged nanotubes and a\n\"shell\" (\"coat\") of incorporated and adjacent nematic molecules. The aggregates\nof this type can be considered as large quasi-macroscopic particles in the\nnematic matrix. The resulting composite system represents a new type of complex\nmolecular liquids involving self-organization of particles in anisotropic\nmedium. Many essential features and implications of the theoretical model\n(e.g., effects of concentration of the nanotubes, their aspect ratio and\norientational order parameter on the size and fractal dimensionality of the\naggregates formed, as well as on the rate of aggregation) are in good agreement\nwith experimental data obtained by various physical methods."
    },
    {
        "anchor": "Tunable out-of-plane excitons in 2D single crystal perovskites: Hybrid organic-inorganic perovskites have emerged as very promising materials\nfor photonic applications, thanks to the great synthetic versatility that\nallows to tune their optical properties. In the two-dimensional (2D)\ncrystalline form, these materials behave as multiple quantum-well\nheterostructures with stable excitonic resonances up to room temperature. In\nthis work strong light-matter coupling in 2D perovskite single-crystal flakes\nis observed, and the polarization-dependent exciton-polariton response is used\nto disclose new excitonic features. For the first time, an out-of-plane\ncomponent of the excitons is observed, unexpected for such 2D systems and\ncompletely absent in other layered materials, such as transition-metal\ndichalcogenides. By comparing different hybrid perovskites with the same\ninorganic layer but different organic interlayers, it is shown how the nature\nof the organic ligands controllably affects the out-of-plane exciton-photon\ncoupling. Such vertical dipole coupling is particularly sought in those\nsystems, e.g. plasmonic nanocavities, in which the direction of the field is\nusually orthogonal to the material sheet. Organic interlayers are shown to\naffect also the strong birefringence associated to the layered structure, which\nis exploited in this work to completely rotate the linear polarization degree\nin only few microns of propagation, akin to what happens in metamaterials.",
        "positive": "Electron Counting Capacitance Standard with an improved five-junction\n  R-pump: The Electron Counting Capacitance Standard currently pursued at PTB aims to\nclose the Quantum Metrological Triangle with a final precision of a few parts\nin 10^7. This paper reports the considerable progress recently achieved with a\nnew generation of single-electron tunnelling devices. A five-junction R-pump\nwas operated with a relative charge transfer error of five electrons in 10^7,\nand was used to successfully perform single-electron charging of a cryogenic\ncapacitor. The preliminary result for the single-electron charge quantum has an\nuncertainty of less than two parts in 10^6 and is consistent with the value of\nthe elementary charge."
    },
    {
        "anchor": "Spin-orbit interaction induced singularity of the charge density\n  relaxation propagator: The charge density relaxation propagator of a two dimensional electron\nsystem, which is the slope of the imaginary part of the polarization function,\nexhibits singularities for bosonic momenta having the order of the spin-orbit\nmomentum and depending on the momentum orientation. We have provided an\nintuitive understanding for this non-analytic behavior in terms of the inter\nchirality subband electronic transitions, induced by the combined action of\nBychkov-Rashba (BR) and Dresselhaus (D) spin-orbit coupling. It is shown that\nthe regular behavior of the relaxation propagator is recovered in the presence\nof only one BR or D spin-orbit field or for spin-orbit interaction with equal\nBR and D coupling strengths. This creates a new possibility to influence\ncarrier relaxation properties by means of an applied electric field.",
        "positive": "Shifted Landau levels in curved graphene sheets: We study the Landau levels in curved graphene sheets by measuring the\ndiscrete energy spectrum in the presence of a magnetic field. We observe that\nin rippled graphene sheets, the Landau energy levels satisfy the same square\nroot dependence on the energy quantum number as in flat sheets, $E_n \\sim\n\\sqrt{n}$. Though, we find that the Landau levels in curved sheets are shifted\ntowards lower energies by an amount proportional to the average spatial\ndeformation of the sheet. Our findings are relevant for the quantum Hall effect\nin curved graphene sheets, which is directly related to Landau quantization.\nFor the purpose of this study, we develop a new numerical method, based on the\nquantum lattice Boltzmann method, to solve the Dirac equation on curved\nmanifolds, describing the low-energetic states in strained graphene sheets."
    },
    {
        "anchor": "Manipulation of Spin Transport in Graphene/Transition Metal\n  Dichalcogenide Heterobilayers upon Twisting: Proximity effects are one of the pillars of exotic phenomena and\ntechnological applications of two dimensional materials. However, the\ninteractions nature depends strongly on the materials involved, their\ncrystalline symmetries, and interfacial properties. Here we used large-scale\nfirst-principle calculations to demonstrate that strain and twist-angle are\nefficient knobs to tailor the spin-orbit coupling in graphene transition metal\ndichalcogenide heterobilayers. We found that by choosing a twist-angle of 30\ndegrees, the spin relaxation times increase by two orders of magnitude, opening\na path to improve these heterostructures spin transport capability. Moreover,\nwe demonstrate that strain and twist angle will modify the relative values of\nvalley-Zeeman and Rashba spin-orbit coupling, allowing to tune the system into\nan ideal Dirac-Rashba regime. These results enable us to envision an answer for\nthe variability of spin-orbit coupling found in different experiments and have\nsignificant consequences for applications that depend on polycrystallinity,\nwhere grains form at different orientations.",
        "positive": "Parity effect and spontaneous currents in superconducting nanorings: New physical effects emerge from an interplay between the electron parity\nnumber and persistent currents in superconducting nanorings. An odd electron,\nbeing added to the ring, produces a countercurrent which may substantially\nmodify the ground state properties of the system. In superconducting nanorings\nwith an embedded normal metal layer a novel ``$\\pi /N$-junction'' state can\noccur for the odd number of electrons. Changing this number from even to odd\nyields spontaneous supercurrent in the ground state of such rings without any\nexternally applied magnetic flux. Further peculiar features of the parity\neffect are expected in structures with resonant electron transport across the\nweak link."
    },
    {
        "anchor": "Optical Phonons in Twisted Bilayer Graphene with Gate-Induced Asymmetric\n  Doping: Twisted bilayer graphene (tBLG) devices with ion gel gate dielectrics are\nstudied using Raman spectroscopy in the twist angle regime where a resonantly\nenhanced G band can be observed. We observe prominent splitting and intensity\nquenching on the G Raman band when the carrier density is tuned away from\ncharge neutrality. This G peak splitting is attributed to asymmetric charge\ndoping in the two graphene layers, which reveals individual phonon self-energy\nrenormalization of the two weakly-coupled layers of graphene. We estimate the\neffective interlayer capacitance at low doping density of tBLG using an\ninterlayer screening model. The anomalous intensity quenching of both G peaks\nis ascribed to the suppression of resonant interband transitions between the\ntwo saddle points (van Hove singularities), that are displaced in the momentum\nspace by gate-tuning. In addition, we observe a softening (hardening) of the R\nRaman band, a superlattice-induced phonon mode in tBLG, in electron (hole)\ndoping. Our results demonstrate that gate modulation can be used to control the\noptoelectronic and vibrational properties in tBLG devices.",
        "positive": "2D photonic-crystal optomechanical nanoresonator: We present the optical optimization of an optomechanical device based on a\nsuspended InP membrane patterned with a 2D near-wavelength grating (NWG) based\non a 2D photonic-crystal geometry. We first identify by numerical simulation a\nset of geometrical parameters providing a reflectivity higher than 99.8 % over\na 50-nm span. We then study the limitations induced by the finite value of the\noptical waist and lateral size of the NWG pattern using different numerical\napproaches. The NWG grating, pierced in a suspended InP 265 nm-thick membrane,\nis used to form a compact microcavity involving the suspended nano-membrane as\nend mirror. The resulting cavity has a waist size smaller than 10 $\\mu$m and a\nfinesse in the 200 range. It is used to probe the Brownian motion of the\nmechanical modes of the nanomembrane."
    },
    {
        "anchor": "Coplanar waveguide based ferromagnetic resonance in ultrathin film\n  magnetic nanostructures: impact of conducting layers: We report broadband ferromagnetic resonance (FMR) measurements based on a\ncoplanar waveguide (CPW) of ultrathin magnetic film structures that comprise\nin-plane/out-of-plane decoupled layers deposited on nonmagnetic buffer layers\nof various thickness or other buffer structures with a diverse sheet\nresistance. We show that the excitation of the fundamental mode can be\nsubstantially (up to 10 times) enhanced in the structures deposited on buffer\nlayers with a low sheet resistance in comparison to the structures deposited on\nthin or weakly conducting buffer layers. The results are analyzed in terms of\nshielding of the electromagnetic field of CPW by the conducting buffer layers.\nThe effect of enhancement of FMR absorption can be attractive for applications\nin spintronic devices that utilize magnetization dynamics of ultrathin\nferromagnetic layers.",
        "positive": "Comparison of energy and phase relaxation in metallic wires: We have measured the phase coherence time, $\\tau_{\\phi},$ in long, narrow\nwires of Au, Ag, and Cu, over the temperature range 40 mK-6 K. In the Cu and Au\nwires, $\\tau_{\\phi}$ saturates at low temperature. In the Ag wire,\n$\\tau_{\\phi}$ continues to increase down to the lowest temperatures measured;\nmoreover, its temperature dependence below about 1 K is consistent with\ntheoretical predictions of Altshuler, Aronov and Khmelnitskii published in\n1982. These results cast doubt on recent assertions that saturation of\n$\\tau_{\\phi}$ at low temperature is a universal phenomenon in metal wires. We\ncompare these results with those of recent experiments on energy relaxation in\nsimilar metallic wires. The results of the two experiments are strongly\ncorrelated, suggesting that a single (unknown) mechanism is the cause of the\nenhanced phase and energy relaxation observed in some samples."
    },
    {
        "anchor": "Hall conductivity as the topological invariant in magnetic Brillouin\n  zone in the presence of interactions: Hall conductivity for the intrinsic anomalous quantum Hall effect in\nhomogeneous systems is given by the topological invariant composed of the Green\nfunction depending on momentum of quasiparticle. This expression reveals\ncorrespondence with the mathematical notion of the degree of mapping. A more\ninvolved situation takes place for the quantum Hall effect in the presence of\nexternal magnetic field. In this case the mentioned expression remains valid if\nthe Green function is taken in a specific representation, where it becomes the\ninfinite - dimensional matrix \\cite{Imai:1990zz} or if it is replaced by its\nWigner transformation while ordinary products are replaced by the Moyal\nproducts \\cite{ZW2019}. Both these expressions, unfortunately, are much more\ncomplicated and might be useless for the practical calculations. Here we\nrepresent the alternative representation for the Hall conductivity of a uniform\nsystem in the presence of constant magnetic field. The Hall conductivity is\nexpressed through the Green function taken in Harper representation, when its\nnonhomogeneity is attributed to the matrix structure while functional\ndependence is on one momentum that belongs to magnetic Brillouin zone. Our\nconsideration for the interacting systems is non - perturbative and is based on\nthe Schwinger - Dyson equations truncated in a reasonable way. We demonstrate\nthat in this approximation the expression for the Hall conductivity in Harper\nrepresentation remains valid, where the interacting Green function is to be\nused instead of the non - interacting one. We, therefore, propose that the\nobtained expression may be used for the topological description of fractional\nquantum Hall effect.",
        "positive": "Magnon-polarons in cubic collinear Antiferromagnets: We present a theoretical study of excitations formed by hybridization between\nmagnons and phonons - magnon-polarons - in antiferromagnets. We first outline a\ngeneral approach to determining which magnon and phonon modes can and cannot\nhybridize in a system thereby addressing the qualitative questions concerning\nmagnon-polaron formation. As a specific and experimentally relevant case, we\nstudy Nickel Oxide quantitatively and find perfect agreement with the\nqualitative analysis, thereby highlighting the strength of the former. We find\nthat there are two distinct features of antiferromagnetic magnon-polarons which\ndiffer from the ferromagnetic ones. First, hybridization between magnons and\nthe longitudinal phonon modes is expected in many cubic antiferromagnetic\nstructures. Second, we find that the very existence of certain hybridizations\ncan be controlled via an external magnetic field, an effect which comes in\naddition to the ability to move the magnon modes relative to the phonons modes."
    },
    {
        "anchor": "Universality and self-similar behaviour of non-equilibrium systems with\n  non-Fickian diffusion: Analytical approaches describing non-Fickian diffusion in complex systems are\npresented. The corresponding methods are applied to the study of statistical\nproperties of pyramidal islands formation with interacting adsorbate at\nepitaxial growth. Using the generalized kinetic approach we consider\nuniversality, scaling dynamics and fractal properties of pyramidal islands\ngrowth. In the framework of generalized kinetics, we propose a theoretical\nmodel to examine the numerically obtained data for averaged islands size, the\nnumber of islands and the corresponding universal distribution over the island\nsize.",
        "positive": "Environment-insensitive and gate-controllable photocurrent enabled by\n  bandgap engineering of MoS2 junctions: Two-dimensional (2D) materials are composed of atomically thin crystals with\nan enormous surface-to-volume ratio, and their physical properties can be\neasily subjected to the change of the chemical environment. Encapsulation with\nother layered materials, such as hexagonal boron nitride, is a common practice;\nhowever, this approach often requires inextricable fabrication processes.\nAlternatively, it is intriguing to explore methods to control transport\nproperties in the circumstance of no encapsulated layer. This is very\nchallenging because of the ubiquitous presence of adsorbents, which can lead to\ncharged-impurity scattering sites, charge traps, and recombination centers.\nHere, we show that the short-circuit photocurrent originated from the built-in\nelectric field at the MoS2 junction is surprisingly insensitive to the gaseous\nenvironment over the range from a vacuum of 1X10^(-6) Torr to ambient\ncondition. The environmental insensitivity of the short-circuit photocurrent is\nattributed to the characteristic of the diffusion current that is associated\nwith the gradient of carrier density. Conversely, the photocurrent with bias\nexhibits typical persistent photoconductivity and greatly depends on the\ngaseous environment. The observation of environment-insensitive short-circuit\nphotocurrent demonstrates an alternative method to design device structure for\n2D-material-based optoelectronic applications."
    },
    {
        "anchor": "Single Molecule Transistor based Nanopore for the detection of Nicotine: A nanopore based detection methodology was proposed and investigated for the\ndetection of Nicotine. This technique uses a Single Molecular Transistor (SMT)\nworking as a nanopore operational in the Coulomb Blockade regime. When the\nNicotine molecule is pulled through the nanopore area surrounded by the\nSource(S), Drain(D) and Gate electrodes, the charge stability diagram can\ndetect the presence of the molecule and is unique for a specific molecular\nstructure. Due to the weak coupling between the different electrodes which is\nset by the nanopore size, the molecular energy states stay almost unaffected by\nthe electrostatic environment that can be realised from the charge stability\ndiagram. Identification of different orientation and position of the Nicotine\nmolecule within the nanopore area can be made from specific regions of overlap\nbetween different charge states on the stability diagram that could be used as\nan electronic fingerprint for detection. This method could be advantageous and\nuseful to detect the presence of Nicotine in smoke which is usually performed\nusing chemical chromatography techniques.",
        "positive": "Giant and tunneling magnetoresistance effects from anisotropic and\n  valley-dependent spin-momentum interactions in antiferromagnets: Giant or tunneling magnetoresistance are physical phenomena used for reading\ninformation in commercial spintronic devices. The effects rely on a conserved\nspin current passing between a reference and a sensing ferromagnetic electrode\nin a multilayer structure. Recently, we have proposed that these fundamental\nspintronic effects can be realized in collinear antiferromagnets with staggered\nspin-momentum exchange interaction, which generates conserved spin currents in\nthe absence of a net equilibrium magnetization. Here we elaborate on the\nproposal by presenting archetype model mechanisms for the antiferromagnetic\ngiant and tunneling magnetoresistance effects. The models are based,\nrespectively, on anisotropic and valley-dependent forms of the non-relativistic\nstaggered spin-momentum interaction. Using first principles calculations we\nlink these model mechanisms to real antiferromagnetic materials and predict a\n$\\sim$100\\% scale for the effects. We point out that besides the GMR/TMR\ndetection, our models directly imply the possibility of spin-transfer-torques\nexcitation of the antiferromagnets."
    },
    {
        "anchor": "Flat Bands near Fermi Level of Topological Line Defects on Graphite: Flat bands play an important role in the study of strongly correlated\nphenomena, such as ferromagnetism, superconductivity, and fractional quantum\nHall effect. Here we report direct experimental evidence for the presence of\nflat bands, close to the Fermi level, in one-dimensional topological defects on\ngraphite seen as a pronounced peak in the tunnelling density of states. Our ab\ninitio calculations indicate that the flat bands with vanishing Fermi velocity\noriginate from sp2 dangling bonds (with antibonding nature) of undercoordinated\ncarbon atoms at the edges of the defects. We further demonstrate that the\npresence of flat bands could be a universal behavior of 1D defects of\ngraphene/graphite with undercoordinated carbon atoms at the edges of the\ndefects.",
        "positive": "Resonant Brillouin scattering of excitonic polaritons in\n  multiple-quantum-well structures: We present theoretical and experimental study of resonant Brillouin\nscattering of excitonic polaritons in one-dimensional multiple-quantum-well\nstructure. We obtain general analytical results for the scattering light\nspectra, valid for arbitrary quantum well arrangement. Application of our\ntheory to the specific case of short-period superlattice shows a perfect\nquantitative agreement with experimental results for the height, width and\nposition of the Brillouin scattering peaks and allows us to determine the\nenergy, radiative and nonradiative decay rates of quantum well excitons. We\nreveal the signatures of excitonic polariton formation in the scattering\nspectra and show, that the spectral width and height are strongly sensitive to\nthe number of wells in the sample."
    },
    {
        "anchor": "Topological carbon allotropes: paradigm shift for materials innovation: Topology is a central concept of mathematics, which allows us to distinguish\ntwo isolated rings with linked ones. In material science, researchers\ndiscovered topologically different carbon allotropes in a form of a cage, a\ntube, and a sheet, which have unique translational and rotational symmetries,\ndescribed by a crystallographic group theory, and the atoms are arranged at\nspecific rigid positions in 3-dimensional ($D$) space. However, topological\norders must be robust against deformations, so that we can make completely\ndifferent families of topological materials. Here we propose various\ntopological structures such as knots and links using covalent $\\sigma$ bonds of\ncarbon atoms, while allowing various topologically equivalent arrangements\nusing weak $\\pi$ bonds. By extending this idea, we invented a new 3D carbon\nallotrope, Hopfene, which has periodic arrays of Hopf-links to knit horizontal\nGraphene sheets into vertical ones without connecting by $\\sigma$ bonds.",
        "positive": "Quantum geometric bound and ideal condition for Euler band topology: Understanding the relationship between quantum geometry and topological\ninvariants is a central problem in the study of topological states. In this\nwork, we establish the relationship between the quantum metric and the Euler\ncurvature in two-dimensional systems with space-time inversion $I_{ST}$\nsymmetry satisfying $I^2_{ST}=+1$. As $I_{ST}$ symmetry imposes the reality of\nthe wave function with vanishing Berry curvature, the well-known inequality\nbetween the quantum metric and the Berry curvature is not meaningful in this\nclass of systems. We find that the non-abelian quantum geometric tensor of two\nreal bands exhibits an intriguing inequality between the off-diagonal Berry\ncurvature and the quantum metric, which in turn gives the inequality between\nthe quantum volume and the Euler invariant. Moreover, we show that the\nsaturation condition of the inequality is deeply related to the ideal condition\nfor Euler bands, which provides a criterion for the stability of fractional\ntopological phases in interacting Euler bands. Our findings demonstrate the\npotential of the quantum geometry as a powerful tool for characterizing\nsymmetry-protected topological states and their interaction effect."
    },
    {
        "anchor": "Isotopic identification of engineered nitrogen-vacancy spin qubits in\n  ultrapure diamond: Nitrogen impurities help to stabilize the negatively-charged-state of NV$^-$\nin diamond, whereas magnetic fluctuations from nitrogen spins lead to\ndecoherence of NV$^-$ qubits. It is not known what donor concentration\noptimizes these conflicting requirements. Here we used 10-MeV $^{15}$N$^{3+}$\nion implantation to create NV$^-$ in ultrapure diamond. Optically detected\nmagnetic resonance of single centers revealed a high creation yield of\n$40\\pm3$% from $^{15}$N$^{3+}$ ions and an additional yield of $56\\pm3$% from\n$^{14}$N impurities. High-temperature anneal was used to reduce residual\ndefects, and charge stable NV$^-$, even in a dilute $^{14}$N impurity\nconcentration of 0.06 ppb were created with long coherence times.",
        "positive": "Shubnikov-de Haas oscillations in optical conductivity of monolayer\n  MoSe$_2$: We report polarization-resolved resonant reflection spectroscopy of a\ncharge-tunable atomically-thin valley semiconductor hosting tightly bound\nexcitons coupled to a dilute system of fully spin- and valley-polarized holes\nin the presence of a strong magnetic field. We find that exciton-hole\ninteractions manifest themselves in hole-density dependent, Shubnikov-de\nHaas-like oscillations in the energy and line broadening of the excitonic\nresonances. These oscillations are evidenced to be precisely correlated with\nthe occupation of Landau levels, thus demonstrating that strong interactions\nbetween the excitons and Landau-quantized itinerant carriers enable optical\ninvestigation of quantum-Hall physics in transition metal dichalcogenides."
    },
    {
        "anchor": "Broken SU(4) symmetry in a Kondo-correlated carbon nanotube: Understanding the interplay between many-body phenomena and non-equilibrium\nin systems with entangled spin and orbital degrees of freedom is a central\nobjective in nano-electronics. We demonstrate that the combination of Coulomb\ninteraction, spin-orbit coupling and valley mixing results in a particular\nselection of the inelastic virtual processes contributing to the Kondo\nresonance in carbon nanotubes at low temperatures. This effect is dictated by\nconjugation properties of the underlying carbon nanotube spectrum at zero and\nfinite magnetic field. Our measurements on a clean carbon nanotube are\ncomplemented by calculations based on a new approach to the non-equilibrium\nKondo problem which well reproduces the rich experimental observations in Kondo\ntransport.",
        "positive": "Influence of temperature gradients on tunnel junction thermometry below\n  1 K: cooling and electron-phonon coupling: We have studied thermal gradients in thin Cu and AlMn wires, both\nexperimentally and theoretically. In the experiments, the wires were Joule\nheated non-uniformly at sub-Kelvin temperatures, and the resulting temperature\ngradients were measured using normal metal-insulator-superconducting tunnel\njunctions. The data clearly shows that even in reasonably well conducting thin\nwires with a short ($\\sim 10 \\mu$m) non-heated portion, significant temperature\ndifferences can form. In most cases, the measurements agree well with a model\nwhich includes electron-phonon interaction and electronic thermal conductivity\nby the Wiedemann-Franz law."
    },
    {
        "anchor": "Epitaxial Growth of Two-dimensional Insulator Monolayer Honeycomb BeO: The emergence of two-dimensional (2D) materials launched a fascinating\nfrontier of flatland electronics. Most crystalline atomic layer materials are\nbased on layered van der Waals materials with weak interlayer bonding, which\nnaturally leads to thermodynamically stable monolayers. We report the synthesis\nof a 2D insulator comprised of a single atomic sheet of honeycomb structure BeO\n(h-BeO), although its bulk counterpart has a wurtzite structure. The h-BeO is\ngrown by molecular beam epitaxy (MBE) on Ag(111) thin films that are\nconveniently grown on Si(111) wafers. Using scanning tunneling microscopy and\nspectroscopy (STM/S), the honeycomb BeO lattice constant is determined to be\n2.65 angstrom with an insulating band gap of 6 eV. Our low energy electron\ndiffraction (LEED) measurements indicate that the h-BeO forms a continuous\nlayer with good crystallinity at the millimeter scale. Moir\\'e pattern analysis\nshows the BeO honeycomb structure maintains long range phase coherence in\natomic registry even across Ag steps. We find that the interaction between the\nh-BeO layer and the Ag(111) substrate is weak by using STS and complimentary\ndensity functional theory calculations. We not only demonstrate the feasibility\nof growing h-BeO monolayers by MBE, but also illustrate that the large-scale\ngrowth, weak substrate interactions, and long-range crystallinity make h-BeO an\nattractive candidate for future technological applications. More significantly,\nthe ability to create a stable single crystalline atomic sheet without a bulk\nlayered counterpart is an intriguing approach to tailoring novel 2D electronic\nmaterials.",
        "positive": "Universal Deoxidation of Semiconductor Substrates Assisted by\n  Machine-Learning and Real-Time-Feedback-Control: Thin film deposition is an essential step in the semiconductor process.\nDuring preparation or loading, the substrate is exposed to the air unavoidably,\nwhich has motivated studies of the process control to remove the surface oxide\nbefore thin film deposition. Optimizing the deoxidation process in molecular\nbeam epitaxy (MBE) for a random substrate is a multidimensional challenge and\nsometimes controversial. Due to variations in semiconductor materials and\ngrowth processes, the determination of substrate deoxidation temperature is\nhighly dependent on the grower's expertise; the same substrate may yield\ninconsistent results when evaluated by different growers. Here, we employ a\nmachine learning (ML) hybrid convolution and vision transformer (CNN-ViT)\nmodel. This model utilizes reflection high-energy electron diffraction (RHEED)\nvideo as input to determine the deoxidation status of the substrate as output,\nenabling automated substrate deoxidation under a controlled architecture. This\nalso extends to the successful application of deoxidation processes on other\nsubstrates. Furthermore, we showcase the potential of models trained on data\nfrom a single MBE equipment to achieve high-accuracy deployment on other\nequipment. In contrast to traditional methods, our approach holds exceptional\npractical value. It standardizes deoxidation temperatures across various\nequipment and substrate materials, advancing the standardization research\nprocess in semiconductor preparation, a significant milestone in thin film\ngrowth technology. The concepts and methods demonstrated in this work are\nanticipated to revolutionize semiconductor manufacturing in optoelectronics and\nmicroelectronics industries by applying them to diverse material growth\nprocesses."
    },
    {
        "anchor": "Spectroscopic confirmation of linear relation between Heisenberg- and\n  interfacial Dzyaloshinskii-Moriya-exchange in polycrystalline metal films: Proposals for novel spin-orbitronic logic1 and memory devices2 are often\npredicated on assumptions as to how materials with large spin-orbit coupling\ninteract with ferromagnets when in contact. Such interactions give rise to a\nhost of novel phenomena, such as spin-orbit torques3,4 , chiral\nspin-structures5,6 and chiral spin-torques. These chiral properties are related\nto the anti-symmetric exchange, also referred to as the interfacial\nDzyaloshinskii-Moriya interaction (DMI)9,10. For numerous phenomena, the\nrelative strengths of the symmetric Heisenberg exchange and the DMI is of great\nimportance. Here, we use optical spin-wave spectroscopy (Brillouin light\nscattering) to directly determine the DMI vector for a series of Ni80Fe20/Pt\nsamples, and then compare the nearest-neighbor DMI coupling energy with the\nindependently measured Heisenberg exchange integral. We find that the\nNi80Fe20-thickness-dependencies of both the microscopic symmetric- and\nantisymmetric-exchange are identical, consistent with the notion that the basic\nmechanisms of the DMI and Heisenberg exchange essentially share the same\nunderlying physics, as was originally proposed by Moriya11. While of\nsignificant fundamental importance, this result also leads us to a deeper\nunderstanding of DMI and how it could be optimized for spin-orbitronic\napplications.",
        "positive": "Excitonic effects in twisted bilayer graphene: In the present work, we consider the excitonic effects in the twisted bilayer\ngraphene (tBLG) within the rotated bilayer Hubbard model. Both, intralayer and\ninterlayer Coulomb interactions have been considered and the half-filling\ncondition is imposed for the electronic densities is both layers of the\nbilayer. We calculate the excitonic pairing gap parameter and the chemical\npotential for different twist angles and different values of the interlayer\nCoulomb interaction parameter. Furthermore, we show the appearance of the\nelectronic flat bands in the electronic band structure, mediated by the\nexcitonic effects. We show that there is a doubling effect of the Dirac's\n$K$-point at the low interaction limit and one of Dirac's nodes is stable and\nthe other one changes its position as a function of rotation angle. At the\nlarge twist angle limit, there appear two additional Dirac-like nodes at the\n$M$-point in the Brillouin zone. We show the excitonic red-shift effect of the\nprincipal Dirac's point $K$, in the low interaction limit, while, at the strong\ninteractions, we get also the blue-shift effect at the $M$-point. Apart from\nthe mentioned effects, the theory evaluated here predicts a metal-semiconductor\ntransition in the tBLG system when augmenting the interlayer Coulomb\ninteraction parameter."
    },
    {
        "anchor": "Atomically-precise engineering of spin-orbit polarons in a kagome\n  magnetic Weyl semimetal: Atomically-precise engineering of defects in topological quantum materials,\nwhich is essential for constructing new artificial quantum materials with\nexotic properties and appealing for practical quantum applications, remains\nchallenging due to the hindrances in modifying complex lattice with atomic\nprecision. Here, we report the atomically-precise engineering of the\nvacancy-localized spin-orbital polarons (SOP) in a kagome magnetic Weyl\nsemimetal Co3Sn2S2, using scanning tunneling microscope. We achieve the\nstep-by-step repairing of the selected vacancies, which results in the\nformation of artificial sulfur vacancy with elaborate geometry. We find that\nthat the bound states localized around the vacancies experience a\nsymmetry-dependent energy shift towards Fermi level with increasing vacancy\nsize. Strikingly, as vacancy size increases, the localized magnetic moments of\nSOPs are tunable and ultimately extended to the negative magnetic moments\nresulting from spin-orbit coupling in the kagome flat band. These findings\nestablish a new platform for engineering atomic quantum states in topological\nquantum materials, offering potential for kagome-lattice-based spintronics and\nquantum technologies.",
        "positive": "Radiation-induced quantum Fano-type resonances in the transport of\n  $N$-$P$-$N$ graphene based junctions: We present a theoretical study of quantum resonances in the ballistic\ntransport of graphene based $N$-$P$-$N$ junction subject to an externally\napplied electromagnetic field (EF). By making use of the Floquet analysis and\nthe quasi-classical approach we analyze the dynamics of electrons in the\npresence of time and coordinate dependent potential $U(z,t)$. In the absence of\nEF the resonant tunneling results in a set of sharp resonances in the\ndependence of dc conductance $\\sigma$ on the gate voltage $V_g$. In irradiated\n$N$-$P$-$N$ junctions we obtain the Fano-type resonances in the dependence of\n$\\sigma(V_g)$. This \\emph{coherent quantum-mechanical phenomenon} is due to the\ninterplay of two effects: the resonant tunneling through quasi-bound states and\nthe quantum-interference effect in the region between the \"resonant points\",\nwhere the resonant absorption (emission) of photons occurs, and junction\ninterfaces."
    },
    {
        "anchor": "Electron Spin Dephasing and Optical Pumping of Nuclear Spins in GaN: We have measured the donor-bound electron spin dynamics in cubic GaN by\ntime-resolved Kerr rotation experiments. The ensemble electron spin dephasing\ntime in this quantum dot like system characterized by a Bohr radius of 2.5 nm\nis of the order of 1.5 ns as a result of the interaction with the fluctuating\nnuclear spins. It increases drastically when an external magnetic field as\nsmall as 10 mT is applied. We extract a dispersion of the nuclear hyperfine\nfield {\\delta}Bn $\\sim$ 4 mT, in agreement with calculations. We also\ndemonstrate for the first time in GaN based systems the optical pumping of\nnuclear spin yielding the build-up of a significant nuclear polarization.",
        "positive": "D'yakonov-Perel' spin relaxation under electron-electron collisions in\n  n-type QWs: The D'yakonov-Perel' spin relaxation mechanism in n-doped GaAs/AlGaAs quantum\nwells (QWs) has been studied both theoretically and experimentally. The\ntemperature dependence of the spin relaxation time has been calculated for\narbitrary degeneracy of the 2D electron gas. The comparison between theory and\nexperiment shows that, in high-mobility n-doped QWs, the studied spin\ndecoherence is controlled by electron-electron collisions."
    },
    {
        "anchor": "Transport across an Anderson quantum dot in the intermediate coupling\n  regime: We describe linear and nonlinear transport across a single impurity Anderson\nmodel quantum dot with intermediate coupling to the leads, i.e., with tunnel\ncoupling of the order of the thermal energy k_B T. The coupling is large enough\nthat sequential tunneling processes alone do not suffice to properly describe\nthe transport characteristics. Upon applying a density matrix approach, the\ncurrent is expressed in terms of rates obtained by considering a very small\nclass of diagrams which dress the sequential tunneling processes by charge\nfluctuations. We call this the \"dressed second order\" (DSO) approximation. One\nmajor achievement of the DSO is that, still in the Coulomb blockade regime, it\ncan describe the crossover from thermally broadened to tunneling broadened\nconductance peaks. When the temperature is decreased even further, the DSO\ncaptures \"Kondesque\" behaviours of the Anderson quantum dot qualitatively: We\nfind a zero bias anomaly of the differential conductance versus applied bias,\nan enhancement of the conductance with decreasing temperature as well as the\nonset of universality of the shape of the conductance as function of the\ntemperature. We can address the case of a spin-degenerate level split\nenergetically by a magnetic field and show that, if we assume in addition\ndifferent capacitive couplings of the two spin-levels to the leads, one of the\nresonance peaks is vanishing. In case spin-dependent chemical potentials are\nintroduced and only one of the four is varied, the DSO yields in principle only\none resonance. This seems to be in agreement with experiments with pseudo-spin.\nFurthermore, we get qualitative agreement with experimental data showing a\ncross-over from the Kondo to the empty orbital regime.",
        "positive": "Microwave-induced dynamic switching of magnetic skyrmion cores in\n  nanodots: The nonlinear dynamic behavior of a magnetic skyrmion in circular nanodots\nwas studied numerically by solving the Landau-Lifshitz-Gilbert equation with a\nclassical spin model. We show that a skyrmion core reversal can be achieved\nwithin nanoseconds using a perpendicular oscillating magnetic field. Two\nsymmetric switching processes that correspond to excitations of the breathing\nmode and the mixed mode (combination of the breathing mode and a radial\nspin-wave mode) are identified. For excitation of the breathing mode, the\nskyrmion core switches through nucleation of a new core from a transient\nuniform state. In the mixed mode, the skyrmion core reverses with the help of\nspins excited both at the edge and core regions. Unlike the magnetic vortex\ncore reversal, the excitation of radial spin waves does not dominate the\nskyrmion core reversal process."
    },
    {
        "anchor": "Influence of roughness on near-field heat transfer between two plates: The surface roughness correction to the near-field heat transfer between two\nrough bulk materials is discussed by using second-order perturbation theory.\nThe results allow for estimating the impact of surface roughness to the heat\ntransfer in recent experiments between two plates and between a microsphere and\na plate (using the Derjaguin approximation). Furthermore, we show that the\nproximity approximation for describing rough surfaces is valid for distances\nmuch smaller than the correlation length of the surface roughness even if the\nheat transfer is dominated by the coupling of surface modes.",
        "positive": "Effect of temperature and bias voltage on the conductance distribution\n  of disordered 1d quantum wires: The statistical properties of the conductance of one dimensional disordered\nsystems are studied at finite bias voltage V and temperature T, in an\nindependent-electron picture. We calculate the complete distribution of the\nconductance P(G) in different regimes of V, T within a statistical model of\nresonant tunneling transmission. We find that P(G) changes from the well-known\nlog-normal distribution at T=0 in the linear response regime to a Gaussian\ndistribution at large V, T. The dependence on T and V of average quantities\nsuch as < G >, < ln G > is analyzed as well. Our analytical results are\nconfirmed by numerical simulations. We also discuss the limits of validity of\nthe model and conclude that the effects of finite T, V presented here should be\nobservable."
    },
    {
        "anchor": "Spin reversal in Fe8 under fast pulsed magnetic fields: We report measurements on magnetization reversal in the Fe$_8$ molecular\nmagnet using fast pulsed magnetic fields of 1.5 kT/s and in the temperature\nrange of 0.6-4.1 K. We observe and analyze the temperature dependence of the\nreversal process, which involves in some cases several resonances. Our\nexperiments allow observation of resonant quantum tunneling of magnetization up\nto a temperature of $\\sim$ 4 K. We also observe shifts of the resonance fields\nin temperature that suggest the emergence of a thermal instability---a\ncombination of spin reversal and self-heating that may result in a magnetic\ndeflagration process. The results are mainly understood in the framework of\nthermally-activated quantum tunneling transitions in combination with emergence\nof a thermal instability.",
        "positive": "Finite-size scaling analysis of the conductivity of Dirac electrons on a\n  surface of disordered topological insulators: Two-dimensional (2D) massless Dirac electrons appear on a surface of\nthree-dimensional topological insulators. The conductivity of such a 2D Dirac\nelectron system is studied for strong topological insulators in the case of the\nFermi level being located at the Dirac point. The average conductivity\n$\\langle\\sigma\\rangle$ is numerically calculated for a system of length $L$ and\nwidth $W$ under the periodic or antiperiodic boundary condition in the\ntransverse direction, and its behavior is analyzed by applying a finite-size\nscaling approach. It is shown that $\\langle\\sigma\\rangle$ is minimized at the\nclean limit, where it becomes scale-invariant and depends only on $L/W$ and the\nboundary condition. It is also shown that once disorder is introduced,\n$\\langle\\sigma\\rangle$ monotonically increases with increasing $L$. Hence, the\nsystem becomes a perfect metal in the limit of $L \\to \\infty$ except at the\nclean limit, which should be identified as an unstable fixed point. Although\nthe scaling curve of $\\langle\\sigma\\rangle$ strongly depends on $L/W$ and the\nboundary condition near the unstable fixed point, it becomes almost independent\nof them with increasing $\\langle\\sigma\\rangle$, implying that it asymptotically\nobeys a universal law."
    },
    {
        "anchor": "Aharonov-Bohm oscillations in disordered topological insulator nanowires: A direct signature of electron transport at the metallic surface of a\ntopological insulator is the Aharonov-Bohm oscillation observed in a recent\nstudy of Bi_2Se_3 nanowires [Peng et al., Nature Mater. 9, 225 (2010)] where\nconductance was found to oscillate as a function of magnetic flux $\\phi$\nthrough the wire, with a period of one flux quantum $\\phi_0=h/e$ and maximum\nconductance at zero flux. This seemingly agrees neither with diffusive theory,\nwhich would predict a period of half a flux quantum, nor with ballistic theory,\nwhich in the simplest form predicts a period of $\\phi_0$ but a minimum at zero\nflux due to a nontrivial Berry phase in topological insulators. We show how h/e\nand h/2e flux oscillations of the conductance depend on doping and disorder\nstrength, provide a possible explanation for the experiments, and discuss\nfurther experiments that could verify the theory.",
        "positive": "Scattering of electrons from an interacting region: We address the problem of transmission of electrons between two\nnoninteracting leads through a region where they interact (quantum dot). We use\na model of spinless electrons hopping on a one-dimensional lattice and with an\ninteraction on a single bond. We show that all the two-particle scattering\nstates can be found exactly. Comparisons are made with numerical results on the\ntime evolution of a two-particle wave packet and several interesting features\nare found for scattering. For N particles the scattering state is obtained by\nperturbation theory. For a dot connected to Fermi seas at different chemical\npotentials, we find an expression for the change in the Landauer current\nresulting from the interactions on the dot. We end with some comments on the\ncase of spin-1/2 electrons."
    },
    {
        "anchor": "High-Quality BN-Graphene-BN Nanoribbon Capacitors Modulated by Graphene\n  Side-gate Electrodes: High-quality BN-Graphene-BN nanoribbon capacitors with double side-gates of\ngraphene are experimentally realized. Graphene electronic properties can be\nsignificantly modulated by the double side-gates. The modulation effects are\nvery obvious and followed the metallic electrode behavior of numerical\nsimulations, while the theoretically predicted negative quantum capacitance was\nnot observed, possibility due to the over-estimated or weakened interactions\nbetween the graphene nanoribbon and side-gate electrodes.",
        "positive": "Anyonic Mach-Zehnder interferometer on a single edge of a 2D electron\n  gas: Anyonic Fabry-P\\'erot and Mach-Zehnder interferometers have been proposed\ntheoretically and implemented experimentally as tools to probe electric charges\nand statistics of anyons. The experimentally observed visibility of\nAharonov-Bohm oscillations is maximal at a high transmission through an\ninterferometer but simple theoretical expressions for the electric currents and\nnoises are only available at low visibility. We consider an alternative version\nof a Mach-Zehnder interferometer, in which anyons tunnel between co-propagating\nchiral channels on the edges of quantum Hall liquids at the filling factors\n$n/(2n+1)$. We find simple exact solutions for any transmission. The solutions\nallow a straight-forward interpretation in terms of fractional charges and\nstatistics."
    },
    {
        "anchor": "Intervalley scattering by charged impurities in graphene: Intervalley charged-impurity scattering processes are examined. It is found\nthat the scattering probability is enhanced due to the Coulomb interaction with\nthe impurity by the Sommerfield factor $F_Z\\propto\n\\epsilon^{2\\sqrt{1-4g^2}-2}$, where $\\epsilon$ is the electron energy and $g$\nis the dimensionless constant of the Coulomb interaction.",
        "positive": "Chaotic Transport in the Symmetry Crossover Regime with a Spin-orbit\n  Interaction: We study a chaotic quantum transport in the presence of a weak spin-orbit\ninteraction. Our theory covers the whole symmetry crossover regime between\ntime-reversal invariant systems with and without a spin-orbit interaction. This\nsituation is experimentally realizable when the spin-orbit interaction is\ncontrolled in a conductor by applying an electric field. We utilize a\nsemiclassical approach which has recently been developed. In this approach, the\nnon-Abelian nature of the spin diffusion along a classical trajectory plays a\ncrucial role. New analytical expressions with one crossover parameter are\nsemiclassically derived for the average conductance, conductance variance and\nshot noise. Moreover numerical results on a random matrix model describing the\ncrossover from the GOE (Gaussian Orthogonal Ensemble) to the GSE (Gaussian\nSymplectic Ensemble) are compared with the semiclassical expressions."
    },
    {
        "anchor": "Kondo effect and channel mixing in oscillating molecules: We investigate the electronic transport through a molecule in the Kondo\nregime. The tunneling between the electrode and the molecule is asymmetrically\nmodulated by the oscillations of the molecule, i.e., if the molecule gets\ncloser to one of the electrodes the tunneling to that electrode will increase\nwhile for the other electrode it will decrease. The system is described by a\ntwo-channel Anderson model with phonon-assisted hybridization, which is solved\nwith the Wilson numerical renormalization group method. The results for several\nfunctional forms of tunneling modulation are presented. For a linearized\nmodulation the Kondo screening of the molecular spin is caused by the even or\nodd conduction channel. At the critical value of the electron-phonon coupling\nan unstable two-channel Kondo fixed point is found. For a realistic modulation\nthe spin at the molecular orbital is Kondo screened by the even conduction\nchannel even in the regime of strong coupling. A universal consequence of the\nelectron-phonon coupling is the softening of the phonon mode and the related\ninstability to perturbations that break the left-right symmetry. When the\nfrequency of oscillations decreases below the magnitude of such perturbation,\nthe molecule is abruptly attracted to one of the electrodes. In this regime,\nthe Kondo temperature is enhanced and, simultaneously, the conductance through\nthe molecule is suppressed.",
        "positive": "Photon Statistics in Collective Strong Coupling: Nano- and Microcavities: There exists a growing interest in the properties of the light generated by\nhybrid systems involving a mesoscopic number of emitters as a means of\nproviding macroscopic quantum light sources. In this work, the quantum\ncorrelations of the light emitted by a collection of emitters coupled to a\ngeneric optical cavity are studied theoretically using an effective Hamiltonian\napproach. Starting from the single-emitter level, we analyse the persistence of\nphoton antibunching as the ensemble size increases. Not only is the photon\nblockade effect identifiable, but photon antibunching originated from\ndestructive interference processes (the so-called unconventional antibunching)\nis also present. We study the dependence of these two types of negative\ncorrelations on the spectral detuning between cavity and emitters, as well as\nits evolution as the time delay between photon detections increases. Throughout\nthis work, the performance of plasmonic nanocavities and dielectric\nmicrocavities is compared: despite the distinct energy scales and the\ndifferences introduced by their respectively open and closed character, the\nbunching and antibunching phenomenology presents remarkable similarities in\nboth types of cavities."
    },
    {
        "anchor": "Multi-gap topology and non-Abelian braiding of phonons from first\n  principles: Non-Abelian states of matter, in which the final state depends on the order\nof the interchanges of two quasiparticles, can encode information immune from\nenvironmental noise with the potential to provide a robust platform for\ntopological quantum computation. We demonstrate that phonons can carry\nnon-Abelian frame charges at the band crossing points of their frequency\nspectrum, and that external stimuli can drive their braiding. We present a\ngeneral framework to understand the topological configurations of phonons from\nfirst principles calculations using a topological invariant called Euler class,\nand provide a complete analysis of phonon braiding by combining different\ntopological configurations. Taking a well-known dielectric material,\nAl$_2$O$_3$, as a representative example, we demonstrate that electrostatic\ndoping gives rise to phonon band inversions that can induce redistribution of\nthe frame charges, leading to non-Abelian braiding of phonons. Our work\nprovides a new quasiparticle platform for realizable non-Abelian braiding in\nreciprocal space, and expands the toolset for studying braiding processes.",
        "positive": "Magnon Hall effect and anisotropic thermal transport in NiFe and YIG\n  ferromagnets: The Righi-Leduc effect refers to the thermal analogue of the Hall effect, for\nwhich the electric current is replaced by the heat current and the electric\nfield by the temperature gradient. In both cases, the magnetic field generates\na transverse force that deviates the carriers (electron, phonon, magnon) in the\ndirection perpendicular to the current. In a ferromagnet, the magnetization\nplays the role of the magnetic field, and the corresponding effect is called\nanomalous Hall effect. Furthermore, a second transverse contribution due to the\nanisotropy, the planar Hall effect, is superimposed to the anomalous Hall\neffect. We report experimental evidence of the thermal counterpart of the Hall\neffects in ferromagnets, namely the magnon Hall effect (or equivalently the\nanomalous Righi-Leduc effect) and the planar Righi-Leduc effect, measured on\nferromagnets that are either electrical conductor (NiFe) or insulator (YIG).\nThe study shows the universal character of these new thermokinetic effects,\nrelated to the intrinsic chirality of the anisotropic ferromagnetic degrees of\nfreedom."
    },
    {
        "anchor": "Variety of scenarios of the magnetic exchange response in topological\n  insulators: We present an ab initio relativistic k.p theory of the effect of magnetic\nexchange field on the band structure in the gap region of bulk crystals and\nthin films of three-dimensional layered topological insulators. For the field\nperpendicular to the layers (along $z$), we reveal novel unconventional\nscenarios of the response of the band-gap edges to the magnetization. The\nmodification of the valence and conduction states is considered in terms of\ntheir $\\Gamma$-point spin $s^z$ and total angular momentum $J^z$ on the atomic\nsites where the states are localized. The actual scenario depends on whether\n$s^z$ and $J^z$ have the same or opposite sign. In particular, the opposite\nsign for the valence state and the same sign for the conduction state give rise\nto an unconventional response in Bi$_2$Te$_3$ -- both in the bulk crystal and\nin ultra-thin films, which fundamentally distinguishes this topological\ninsulator from Bi$_2$Se$_3$, where both states have the same sign. To gain a\ndeeper insight into different scenarios in insulators with both inverted and\nnon-inverted zero-field band structure, a minimal four-band third-order k.p\nmodel is constructed from first principles. Within this model, we analyze the\nfield-induced band structure of the insulators and identify Weyl nodes that\nappear in a magnetic phase and behave differently depending on the scenario. We\ncharacterize the topology of the modified band structure by the Chern number\n$\\mathcal{C}$ and find the unconventional response to be accompanied by a large\nChern number $\\mathcal{C}=\\pm3$.",
        "positive": "Topological Nonlinear Anomalous Nersnt Effect in Strained Transition\n  Metal Dichalcogenides: We theoretically analyze the non-linear anomalous Nernst effect as the\nsecond-order response of temperature gradient by using the semiclassical\nframework of electron dynamics. We find that a non-linear current can be\ngenerated transverse to the applied temperature gradient in\ntime-reversal-symmetry materials with broken inversion symmetry. This effect\nhas a quantum origin arising from the Berry curvature of states near the Fermi\nsurface. We discuss the non-linear Nernst effect in transition metal\ndichalcogenides~(TMDCs) under the application of uniaxial strain. In\nparticular, we predict that under fixed chemical potential in TMDCs, the\nnon-linear Nernst current exhibits a transition from\n$\\textbf{j}^\\text{dip}_\\text{A}\\sim T^{-2}$ temperature dependence in low\ntemperature regime to a linear $T$-dependence in high temperature."
    },
    {
        "anchor": "Review of performance metrics of spin qubits in gated semiconducting\n  nanostructures: This Technical Review collects values of selected performance characteristics\nof semiconductor spin qubits defined in electrically controlled nanostructures.\nThe characteristics are envisioned to serve as a community source for the\nvalues of figures of merit with agreed-on definitions allowing the comparison\nof different spin qubit platforms. We include characteristics on the qubit\ncoherence, speed, fidelity, and the qubit-size of multiqubit devices. The focus\nis on collecting and curating the values of these characteristics as reported\nin the literature, rather than on their motivation or significance.",
        "positive": "Coherent frequency conversion in a superconducting artificial atom with\n  two internal degrees of freedom: By adding a large inductance in a dc-SQUID phase qubit loop, one decouples\nthe junctions' dynamics and creates a superconducting artificial atom with two\ninternal degrees of freedom. In addition to the usual symmetric plasma mode\n({\\it s}-mode) which gives rise to the phase qubit, an anti-symmetric mode\n({\\it a}-mode) appears. These two modes can be described by two anharmonic\noscillators with eigenstates $\\ket{n_{s}}$ and $\\ket{n_{a}}$ for the {\\it s}\nand {\\it a}-mode, respectively. We show that a strong nonlinear coupling\nbetween the modes leads to a large energy splitting between states\n$\\ket{0_{s},1_{a}}$ and $\\ket{2_{s},0_{a}}$. Finally, coherent frequency\nconversion is observed via free oscillations between the states\n$\\ket{0_{s},1_{a}}$ and $\\ket{2_{s},0_{a}}$."
    },
    {
        "anchor": "Fingerprints of single nuclear spin energy levels using STM - ENDOR: We performed STM-ENDOR experiments where the intensity of one of the\nhyperfine components detected in ESR-STM is recorded while an rf power is\nirradiated into the tunneling junction and its frequency is swept. When the\nlatter frequency is near a nuclear transition a dip in ESR-STM signal is\nobserved. This experiment was performed in three different systems: near\nsurface SiC vacancies where the electron spin is coupled to a next nearest\nneighbor 29Si nucleus; Cu deposited on Si(111)7x7 surface, where the unpaired\nelectron of the Cu atom is coupled to the Cu nucleus (63Cu, 65Cu) and on Tempo\nmolecules adsorbed on Au(111), where the unpaired electron is coupled to\nNitrogen nucleus (14N). While some of the hyperfine values are unresolved in\nthe ESR-STM data due to linewidth we find that they are accurately determined\nin the STM-ENDOR data including those from remote nuclei, which are not\ndetected in the ESR-STM spectrum. Furthermore, STM-ENDOR can measure single\nnuclear Zeeman frequencies, distinguish between isotopes through their\ndifferent nuclear magnetic moments and detect quadrupole spectra. We also\ndevelop and solve a Bloch type equation for the coupled electron-nuclear system\nthat facilitates interpretation of the data. The improved spectral resolution\nof STM - ENDOR opens many possibilities for nanometric scale chemical analysis.",
        "positive": "Cryo-Near-Field Photovoltage Microscopy of Heavy-Fermion Twisted\n  Symmetric Trilayer Graphene: Ever since the initial experimental observation of correlated insulators and\nsuperconductivity in the flat Dirac bands of magic angle twisted bilayer\ngraphene, a search for the microscopic description that explains its strong\nelectronic interactions has begun. While the seemingly disagreeing electronic\ntransport and scanning tunneling microscopy experiments suggest a dichotomy\nbetween local and extended electronic orbitals, definitive experimental\nevidence merging the two patterns together has been much sought after. Here, we\nreport on the local photothermoelectric measurements in the flat electronic\nbands of twisted symmetric trilayer graphene (TSTG). We use a cryogenic\nscanning near-field optical microscope with an oscillating atomic force\nmicroscopy (AFM) tip irradiated by the infrared photons to create a nanoscopic\nhot spot in the planar samples, which generates a photocurrent that we probe\nglobally. We observe a breakdown of the non-interacting Mott formalism at low\ntemperatures (10K), signaling the importance of the electronic interactions.\nOur measurements reveal an overall negative offset of the Seebeck coefficient\nand significant peaks of the local photovoltage values at all positive integer\nfillings of the TSTG's moir\\'e superlattice, further indicating a substantial\ndeviation from the classical two-band semiconductor Seebeck response. We\nexplain these observations using the interacting topological heavy-fermion\nmodel. In addition, our data reveal a spatial variation of the relative\ninteraction strength dependent on the measured local twist angle (1.2{\\deg} -\n1.6{\\deg}). Our findings provide experimental evidence of heavy fermion\nbehaviour in the topological flat bands of moir\\'e graphene and epitomize an\navenue to apply local thermoelectric measurements to other strongly correlated\nmaterials in the disorder-free limit."
    },
    {
        "anchor": "Partial preservation of chiral symmetry and colossal magnetoresistance\n  in adatom doped graphene: We analyze the electronic properties of adatom doped graphene in the low\nimpurity concentration regime. We focus on the Anderson localized regime and\ncalculate the localization length ($\\xi$) as a function of the electron doping\nand an external magnetic field. The impurity states hybridize with carbon's\n$p_z$ states and form a partially filled band close to the Dirac point. Near\nthe impurity band center, the chiral symmetry of the system's effective\nHamiltonian is partially preserved which leads to a large enhancement of $\\xi$.\nThe sensitivity of transport properties, namely Mott's variable range hopping\nscale $T_0$, to an external magnetic field perpendicular to the graphene sheet\nleads to a colossal magnetoresistance effect, as observed in recent\nexperiments.",
        "positive": "Berry Curvature, Triangle Anomalies, and the Chiral Magnetic Effect in\n  Fermi Liquids: In a three-dimensional Fermi liquid, quasiparticles near the Fermi surface\nmay possess a Berry curvature. We show that if the Berry curvature has a\nnonvanishing flux through the Fermi surface, the particle number associated\nwith this Fermi surface has a triangle anomaly in external electromagnetic\nfields. We show how Landau's Fermi liquid theory should be modified to take\ninto account the Berry curvature. We show that the \"chiral magnetic effect\"\nalso emerges from the Berry curvature flux."
    },
    {
        "anchor": "Critical scaling of polarization waves on a heterogeneous chain of\n  resonators: The intensity distribution of electromagnetic polar waves in a chain of\nnear-resonant weakly-coupled scatterers is investigated theoretically and\nsupported by a numerical analysis. Critical scaling behavior is discovered for\npart of the eigenvalue spectrum due to the disorder-induced Anderson\ntransition. This localization transition (in a formally one-dimensional system)\nis attributed to the long-range dipole-dipole interaction, which decays inverse\nlinearly with distance for polarization perpendicular to the chain. For\npolarization parallel to the chain, with inverse squared long range coupling,\nall eigenmodes are shown to be localized. A comparison with the results for\nHermitian power-law random banded matrices and other intermediate models is\npresented. This comparison reveals the significance of non-Hermiticity of the\nmodel and the periodic modulation of the coupling.",
        "positive": "Room Temperature Quantum Control of N-Donor Electrons at Si/SiO2\n  Interface: The manuscript theoretically discusses various important aspects for donor\natom based single qubit operations in silicon (Si) quantum computer\narchitecture at room temperature using a single nitrogen (N) deep-donor close\nto the Si/SiO2 interface. Quantitative investigation of room temperature single\nelectron shuttling between a single N-donor atom and the interface is the focus\nof attention under the influence of externally applied electric and magnetic\nfield. To apprehend the realistic experimental configurations, central cell\ncorrection along with effective mass approach is adopted throughout the study.\nFurthermore, a detailed discussion currently explores the significant time\nscales implicated in the process and their suitability for experimental\npurposes. Theoretical estimates are also provided for all the external fields\nrequired to successfully achieve coherent single electron shuttling and their\nstable maintenance at the interface as required. The results presented in this\nwork offer practical guidance for quantum electron control using N-donor atoms\nin Si at room temperature."
    },
    {
        "anchor": "Disorder Dependence of Interface Spin Memory Loss: The discontinuity of a spin-current through an interface caused by spin-orbit\ncoupling is characterized by the spin memory loss (SML) parameter {\\delta}. We\nuse first-principles scattering theory and a recently developed local current\nscheme to study the SML for Au|Pt, Au|Pd, Py|Pt and Co|Pt interfaces. We find a\nminimal temperature dependence for nonmagnetic interfaces and a strong\ndependence for interfaces involving ferromagnets that we attribute to the spin\ndisorder. The SML is larger for Co|Pt than for Py|Pt because the interface is\nmore abrupt. Lattice mismatch and interface alloying strongly enhance the SML\nthat is larger for a Au|Pt than for a Au|Pd interface. The effect of the\nproximity induced magnetization of Pt is negligible.",
        "positive": "Phonon-assisted transitions from quantum dot excitons to cavity photons: For a single semiconductor quantum dot embedded in a microcavity, we\ntheoretically and experimentally investigate phonon-assisted transitions\nbetween excitons and the cavity mode. Within the framework of the independent\nboson model we find that such transitions can be very efficient, even for\nrelatively large exciton-cavity detunings of several millielectron volts.\nFurthermore, we predict a strong detuning asymmetry for the exciton lifetime\nthat vanishes for elevated lattice temperature. Our findings are corroborated\nby experiment, which turns out to be in good quantitative and qualitative\nagreement with theory."
    },
    {
        "anchor": "Mechanical dissipation in MoRe superconducting metal drums: We experimentally investigate dissipation in mechanical resonators made of a\ndisordered superconducting thin film of Molybdenum-Rhenium(MoRe) alloy. By\nelectrostatically driving the drum with a resonant AC voltage, we detect its\nmotion using a superconducting microwave cavity. From the temperature\ndependence of mechanical resonance frequencies and quality factors, we find\nevidence for non-resonant, mechanically active two-level systems (TLSs)\nlimiting its quality factor at low temperature. In addition, we observe a\nstrong suppression of mechanical dissipation at large mechanical driving\namplitudes, suggesting an unconventional saturation of the non-resonant TLSs.\nThese new observations shed light on the mechanism of mechanical damping in\nsuperconducting drums and routes towards understanding dissipation in such\nmechanical systems.",
        "positive": "Minimizing the programming power of phase change memory by using\n  graphene nanoribbon edge-contact: Nonvolatile phase change random access memory (PCRAM) is regarded as one of\npromising candidates for emerging mass storage in the era of Big Data. However,\nrelatively high programming energy hurdles the further reduction of power\nconsumption in PCRAM. Utilizing narrow edge-contact of graphene can effectively\nreduce the active volume of phase change material in each cell, and therefore\nrealize low-power operation. Here, we demonstrate that a write energy can be\nreduced to about ~53.7 fJ in a cell with ~3 nm-wide graphene nanoribbon (GNR)\nas edge-contact, whose cross-sectional area is only ~1 nm2. It is found that\nthe cycle endurance exhibits an obvious dependence on the bias polarity in the\ncell with structure asymmetry. If a positive bias was applied to graphene\nelectrode, the endurance can be extended at least one order longer than the\ncase with reversal of polarity. The work represents a great technological\nadvance for the low power PCRAM and could benefit for in-memory computing in\nfuture."
    },
    {
        "anchor": "An electronic Mach-Zehnder interferometer in the Fractional Quantum Hall\n  effect: We compute the interference pattern of a Mach-Zehnder interferometer\noperating in the fractional quantum Hall effect. Our theoretical proposal is\ninspired by a remarkable experiment on edge states in the Integer Quantum Hall\neffect (IQHE). The Luttinger liquid model is solved via two independent\nmethods: refermionization at nu=1/2 and the Bethe Ansatz solution available for\nLaughlin fractions. The current differs strongly from that of single electrons\nin the strong backscattering regime. The Fano factor is periodic in the flux,\nand it exhibits a sharp transition from sub-Poissonian (charge e/2) to\nPoissonian (charge e) in the neighborhood of destructive interferences.",
        "positive": "Closing the proximity gap in a metallic Josephson junction between three\n  superconductors: We describe the proximity effect in a short disordered metallic junction\nbetween three superconducting leads. Andreev bound states in the multi-terminal\njunction may cross the Fermi level. We reveal that for a quasi-continuous\nmetallic density of states, crossings at the Fermi level manifest as closing of\nthe proximity-induced gap. We calculate the local density of states for a wide\nrange of transport parameters using quantum circuit theory. The gap closes\ninside an area of the space spanned by the superconducting phase differences.\nWe derive an approximate analytic expression for the boundary of the area and\ncompare it to the full numerical solution. The size of the area increases with\nthe transparency of the junction and is sensitive to asymmetry. The finite\ndensity of states at zero energy is unaffected by electron-hole decoherence\npresent in the junction, although decoherence is important at higher energies.\nOur predictions can be tested using tunneling transport spectroscopy. To\nencourage experiments, we calculate the current-voltage characteristic in a\ntypical measurement setup. We show how the structure of the local density of\nstates can be mapped out from the measurement."
    },
    {
        "anchor": "Decoherence from Vacuum Fluctuations: Vacuum fluctuations are a source of irreversibility and decoherence. We\ninvestigate the persistent current and its fluctuations in a ring with an\nin-line quantum dot with an Aharonov-Bohm flux through the hole of the ring.\nThe Coulomb blockade leads to persistent current peaks at values of the gate\nvoltage at which two charge states of the dot have the same free energy. We\ncouple the structure to an external circuit and investigate the effect of the\nzero-temperature (vacuum fluctuations) on the ground state of the ring. We find\nthat the ground state of the ring undergoes a crossover from a state with an\naverage persistent current much larger than the (time-dependent) mean squared\nfluctuations to a state with a small average persistent current and large mean\nsquared fluctuations. We discuss the spectral density of charge fluctuations\nand discuss diffusion rates for angle variables characterizing the ground state\nin Bloch representation.",
        "positive": "Extended Bloch theorem for topological lattice models with open\n  boundaries: While the Bloch spectrum of translationally invariant noninteracting lattice\nmodels is trivially obtained by a Fourier transformation, diagonalizing the\nsame problem in the presence of open boundary conditions is typically only\npossible numerically or in idealized limits. Here we present exact analytic\nsolutions for the boundary states in a number of lattice models of current\ninterest, including nodal-line semimetals on a hyperhoneycomb lattice,\nspin-orbit coupled graphene, and three-dimensional topological insulators on a\ndiamond lattice, for which no previous exact finite-size solutions are\navailable in the literature. Furthermore, we identify spectral mirror symmetry\nas the key criterium for analytically obtaining the entire (bulk and boundary)\nspectrum as well as the concomitant eigenstates, and exemplify this for Chern\nand $\\mathcal Z_2$ insulators with open boundaries of co-dimension one. In the\ncase of the two-dimensional Lieb lattice, we extend this further and show how\nto analytically obtain the entire spectrum in the presence of open boundaries\nin both directions, where it has a clear interpretation in terms of bulk, edge,\nand corner states."
    },
    {
        "anchor": "Universal Quantum Computation with Hybrid Spin-Majorana Qubits: We theoretically propose a set of universal quantum gates acting on a hybrid\nqubit formed by coupling a quantum dot spin qubit and Majorana fermion qubit.\nFirst, we consider a quantum dot tunnel-coupled to two topological\nsuperconductors. The effective spin-Majorana exchange facilitates a hybrid CNOT\ngate for which either qubit can be the control or target. The second setup is a\nmodular scalable network of topological superconductors and quantum dots. As a\nresult of the exchange interaction between adjacent spin qubits, a CNOT gate is\nimplemented that acts on neighboring Majorana qubits, and eliminates the\nnecessity of inter-qubit braiding. In both setups the spin-Majorana exchange\ninteraction allows for a phase gate, acting on either the spin or the Majorana\nqubit, and for a SWAP or hybrid SWAP gate which is sufficient for universal\nquantum computation without projective measurements.",
        "positive": "Discovery of acousto-drag photovoltaic effect: As a key ingredient in energy harvesting and photodetection,\nlight-to-electricity conversion requires efficient separation of photoexcited\nelectron-hole pairs before recombination. Traditional junction-based mechanisms\nmainly use build-in electric fields to achieve pair separation and generate\nphotovoltaic effect, which fail to collect photoexcited pairs away from local\nbarrier region. The ability to harvest photovoltaic effect in a homogeneous\nmaterial upon uniform illumination is appealing, but has only been realized in\nvery few cases such as non-centrosymmetric systems through bulk photovoltaic\neffect. Here we realize a new type of photovoltaic effect, termed as\nacousto-drag photovoltaic effect, by travelling surface acoustic waves (t-SAW)\nin a conventional layered semiconductor MoSe2. Instead of immediately driving\nthe electron-hole pairs to opposite directions after generation, t-SAW induces\nperiodic modulation to electronic bands and drags the photoexcited pairs toward\nthe same travelling direction. The photocurrent can then be extracted by a\nlocal barrier, e.g. the metal-semiconductor contact as we used here. By\nspatially separating the electron-hole generation and extraction processes, the\nacousto-drag mechanism strongly suppresses charge recombination and yields\nlarge nonlocal photoresponse outside the barrier region. We show that when\nt-SAW is applied, the photoresponse can be enhanced by over two orders of\nmagnitude with exceptionally high external quantum efficiency above 60%. The\ndiscovery of acousto-drag photovoltaic effect establishes a new approach\ntowards efficient light-to-electricity conversion without the restriction of\ncrystal symmetry."
    },
    {
        "anchor": "Exceptional rings protected by emergent symmetry for mechanical systems: We propose mechanical systems, described by Newton's equation of motion, as\nsuited platforms for symmetry protection of non-Hermitian topological\ndegeneracies. We point out that systems possess emergent symmetry, which is a\nunique properties of mechanical systems. Because of the emergent symmetry, in\ncontrast to other systems, fine-tuning of parameters (e.g., gain and loss) is\nnot required to preserve the symmetry protecting exceptional rings in two\ndimensions. The presence of symmetry-protected exceptional rings (SPERs) in two\ndimensions is numerically demonstrated for a mechanical graphene with friction.\nFurthermore, classification of symmetry-protected non-Hermitian degeneracies is\naddressed by taking into account the above special characteristics of\nmechanical systems.",
        "positive": "Spontaneous polygonization of multi-walled carbon nanotubes:\n  perturbation analysis: Spontaneous polygonization for a multi-walled carbon nanotubes (MWCNTs) have\nbeen observed for about two decades. In present manuscript, this phenomenon is\nunderstood by the competition between cohesion energy (with lattice mismatching\neffect) and curvature elastic energy of tubes inside the MWCNTs. Based on a\ncontinuum elastic model and perturbation analysis, the crucial conditions for\nspontaneous polygonization of MWCNT is expressed by fundamental parameters of\nMWCNTs, which are in reasonable agreement with all relevant experiments and\ncomputer simulations reported in literatures. Present approach can be used in\nfurther studies of crossectional geometry-dependent properties of MWCNTs."
    },
    {
        "anchor": "Emergence of Chern insulating states in non-Magic angle twisted bilayer\n  graphene: Twisting two layers into a magic angle (MA) of ~1.1{\\deg} is found essential\nto create low energy flat bands and the resulting correlated insulating,\nsuperconducting, and magnetic phases in twisted bilayer graphene (TBG). While\nmost of previous works focus on revealing these emergent states in MA-TBG, a\nstudy of the twist angle dependence, which helps to map an evolution of these\nphases, is yet less explored. Here, we report a magneto-transport study on one\nnon-magic angle TBG device, whose twist angle {\\theta} changes from 1.25{\\deg}\nat one end to 1.43{\\deg} at the other. For {\\theta}=1.25{\\deg}, we observe an\nemergence of topological insulating states at hole side with a sequence of\nChern number |C|=4-|v|, where v is the number of electrons (holes) in moir\\'e\nunite cell. When {\\theta}>1.25{\\deg}, the Chern insulator from flat band\ndisappears and evolves into fractal Hofstadter butterfly quantum Hall insulator\nwhere magnetic flux in one moir\\'e unite cell matters. Our observations will\nstimulate further theoretical and experimental investigations on the\nrelationship between electron interactions and non-trivial band topology.",
        "positive": "Bridging the reality gap in quantum devices with physics-aware machine\n  learning: The discrepancies between reality and simulation impede the optimisation and\nscalability of solid-state quantum devices. Disorder induced by the\nunpredictable distribution of material defects is one of the major\ncontributions to the reality gap. We bridge this gap using physics-aware\nmachine learning, in particular, using an approach combining a physical model,\ndeep learning, Gaussian random field, and Bayesian inference. This approach has\nenabled us to infer the disorder potential of a nanoscale electronic device\nfrom electron transport data. This inference is validated by verifying the\nalgorithm's predictions about the gate voltage values required for a\nlaterally-defined quantum dot device in AlGaAs/GaAs to produce current features\ncorresponding to a double quantum dot regime."
    },
    {
        "anchor": "Magnetic field induced localization in 2D topological insulators: Localization of the helical edge states in quantum spin Hall insulators\nrequires breaking time reversal invariance. In experiments this is naturally\nimplemented by applying a weak magnetic field B. We propse a model based on\nscattering theory that describes the localization of helical edge states due to\ncoupling to random magnetic fluxes. We find that the localization length is\nproportional to B^{2} when B is small, and saturates to a constant when B is\nsufficiently large. We estimate especially the localization length for the\nHgTe/CdTe quantum wells with known experimental parameters.",
        "positive": "Enhanced exciton-exciton collisions in an ultra-flat monolayer MoSe2\n  prepared through deterministic flattening: Squeezing bubbles and impurities out of interlayer spaces by applying force\nthrough a few-layer graphene capping layer leads to van der Waals\nheterostructures with ultra-flat structure free from random electrostatic\npotential arising from charged impurities. Without the graphene capping layer,\na squeezing process with an AFM tip induces applied-force-dependent charges of\nn ~ 2 x 10^12 cm^-2 uN^-1, resulting in strong intensity of trions in\nphotoluminescence spectra of MoSe2 at low temperature. We found that a\nhBN/MoSe2/hBN prepared with the \"modified nano-squeezing method\" shows a strong\nexcitonic emission with negligible trion peak, and the residual linewidth of\nthe exciton peak is only 2.2 meV, which is comparable to the homogeneous limit.\nFurthermore, in this high-quality sample, we found that formation of biexciton\noccurs even at extremely low excitation power (Phi ~ 2.3 x 10^19 cm^-2 s^-1)\ndue to the enhanced collisions between excitons."
    },
    {
        "anchor": "Graphene with adatoms: tuning the magnetic moment with an applied\n  voltage: We show that, in graphene with a small concentration of adatoms, the total\nmagnetic moment $\\mu_T$ can be switched on and off by varying the Fermi energy\n$E_F$, either by applying a gate voltage or by suitable chemical doping. Our\ncalculation is carried out using a simple tight-binding model described\npreviously, combined with a mean-field treatment of the electron-electron\ninteraction on the adatom. The values of $E_F$ at which the moment is turned on\nor off are controlled by the strength of the hopping between the graphene sheet\nand the adatom, the on-site energy of the adatom, and the strength of the\nelectron-electron correlation energy U. Our result is in qualitatively\nconsistent with recent experiments by Nair {\\it et al.} [Nat.\\ Commun.\\ {\\bf\n4}, 2010 (2013)].",
        "positive": "Dynamical leakage of Majorana mode into side-attached quantum dot: We study a hybrid structure, comprising the single-level quantum dot attached\nto the topological superconducting nanowire, inspecting dynamical transfer of\nthe Majorana quasiparticle onto normal region. Motivated by the recent\nexperimental realization of such heterostructure and its investigation under\nthe stationary conditions [L. Schneider et al.,\nhttps://doi.org/10.1038/s41467-020-18540-3, Nature Communications 11, 4707\n(2020)] where the quantum dot energy level can be tuned by gate potential we\nexamine how much time is needed for the Majorana mode to leak into the normal\nregion. We estimate, that for typical hybrid structures this dynamical process\nwould take about 20 nanoseconds. We propose a feasible empirical protocol for\nits detection by means of the time-resolved Andreev tunneling spectroscopy."
    },
    {
        "anchor": "The quantum transverse-field Ising chain in circuit QED: effects of\n  disorder on the nonequilibrium dynamics: We study several dynamical properties of a recently proposed implementation\nof the quantum transverse-field Ising chain in the framework of circuit QED.\nParticular emphasis is placed on the effects of disorder on the nonequilibrium\nbehavior of the system. We show that small amounts of fabrication-induced\ndisorder in the system parameters do not jeopardize the observation of\npreviously-predicted phenomena. Based on a numerical extraction of the mean\nfree path of the system, we also provide a simple quantitative estimate for\ncertain disorder effects on the nonequilibrium dynamics of the circuit QED\nquantum simulator. We discuss the transition from weak to strong disorder,\ncharacterized by the onset of Anderson localization of the system's wave\nfunctions, and the qualitatively different dynamics it leads to.",
        "positive": "Mono- and Bilayer WS2 Light-Emitting Transistors: We have realized ambipolar ionic liquid gated field-effect transistors based\non WS2 mono- and bilayers, and investigated their opto-electronic response. A\nthorough characterization of the transport properties demonstrates the high\nquality of these devices for both electron and hole accumulation, which enables\nthe quantitative determination of the band gap ({\\Delta}1L = 2.14 eV for\nmonolayers and {\\Delta}2L = 1.82 eV for bilayers). It also enables the\noperation of the transistors in the ambipolar injection regime with electrons\nand holes injected simultaneously at the two opposite contacts of the devices\nin which we observe light emission from the FET channel. A quantitative\nanalysis of the spectral properties of the emitted light, together with a\ncomparison with the band gap values obtained from transport, show the internal\nconsistency of our results and allow a quantitative estimate of the excitonic\nbinding energies to be made. Our results demonstrate the power of ionic liquid\ngating in combination with nanoelectronic systems, as well as the compatibility\nof this technique with optical measurements on semiconducting transition metal\ndichalcogenides. These findings further open the way to the investigation of\nthe optical properties of these systems in a carrier density range much broader\nthan that explored until now."
    },
    {
        "anchor": "Observation of anisotropic magneto-inductance effect: We have discovered a new phenomenon that inductance oscillates as a function\nof the angle between an in-plane magnetic field and an electric current\ndirection in permalloy films, which we have named \"the anisotropic\nmagneto-inductance (AML) effect\". We have investigated the dependences of the\nAML effect on the size and voltage. The length, frequency, and amplitude\ndependences suggest that the AML effect should be evaluated in terms of\n\"inductivity\". Inductors based on this AML effect have the potential to be\nvariable, on-chip, and one billion times smaller than the small commercial\ninductor.",
        "positive": "Self-sustained magnetoelectric oscillations in magnetic resonant\n  tunneling structures: The dynamic interplay of transport, electrostatic, and magnetic effects in\nthe resonant tunneling through ferromagnetic quantum wells is theoretically\ninvestigated. It is shown that the carrier-mediated magnetic order in the\nferromagnetic region not only induces, but also takes part in intrinsic,\nrobust, and sustainable high-frequency current oscillations over a large window\nof nominally steady bias voltages. This phenomenon could spawn a new class of\nquantum electronic devices based on ferromagnetic semiconductors."
    },
    {
        "anchor": "Polymer-based black phosphorus (bP) hybrid materials by in situ radical\n  polymerization: an effective tool to exfoliate bP and stabilize bP nanoflakes: Black phosphorus (bP) has been recently investigated for next generation\nnanoelectronic multifunctional devices. However, the intrinsic instability of\nexfoliated bP (the bP nanoflakes) towards both moisture and air has so far\novershadowed its practical implementation. In order to contribute to fill this\ngap, we report here the preparation of new hybrid polymer-based materials where\nbP nanoflakes exhibit a significantly improved stability. The new materials\nhave been prepared by different synthetic paths including: i) the mixing of\nconventionally liquid-phase exfoliated bP (in DMSO) with PMMA solution; ii) the\ndirect exfoliation of bP in a polymeric solution; iii) the in situ radical\npolymerization after exfoliating bP in the liquid monomer (methyl methacrylate,\nMMA). This last methodology concerns the preparation of stable suspensions of\nbPn-MMA by sonication-assisted liquid phase exfoliation (LPE) of bP in the\npresence of MMA followed by radical polymerization. The hybrids characteristics\nhave been compared in order to evaluate the bP dispersion and the effectiveness\nof the bPn interfacial interactions with polymer chains aimed at their\nlong-term environmental stabilization. The passivation of bPn results\nparticularly effective when the hybrid material is prepared by in situ\npolymerization. By using this synthetic methodology, the nanoflakes, even if\nwith a gradient of dispersion (size of aggregates), preserve their chemical\nstructure from oxidation (as proved by both Raman and 31P-Solid State NMR\nstudies) and are particularly stable to air and UV light exposure.",
        "positive": "Real-Space Imaging of Alternate Localization and Extension of Quasi\n  Two-Dimensional Electronic States at Graphite Surfaces in Magnetic Fields: We measured the local density of states (LDOS) of a quasi two-dimensional\n(2D) electron system near point defects on a surface of highly oriented\npyrolytic graphite (HOPG) with scanning tunneling microscopy and spectroscopy.\nDifferential tunnel conductance images taken at very low temperatures and in\nhigh magnetic fields show a clear contrast between localized and extended\nspatial distributions of the LDOS at the valley and peak energies of the Landau\nlevel spectrum, respectively. The localized electronic state has a single\ncircular distribution around the defects with a radius comparable to the\nmagnetic length. The localized LDOS is in good agreement with a spatial\ndistribution of a calculated wave function for a single electron in 2D in a\nCoulomb potential in magnetic fields."
    },
    {
        "anchor": "Magnon-photon coupling in a non-collinear magnetic insulator\n  Cu$_2$OSeO$_3$: Anticrossing behavior between magnons in a non-collinear chiral magnet\nCu$_2$OSeO$_3$ and a two-mode X-band microwave resonator was studied in the\ntemperature range 5-100K. In the field-induced ferrimagnetic phase, we observed\na strong coupling regime between magnons and two microwave cavity modes with a\ncooperativity reaching 3600. In the conical phase, cavity modes are\ndispersively coupled to a fundamental helimagnon mode, and we demonstrate that\nthe magnetic phase diagram of Cu$_2$OSeO$_3$ can be reconstructed from the\nmeasurements of the cavity resonance frequency. In the helical phase, a\nhybridized state of a higher-order helimagnon mode and a cavity mode - a\nhelimagnon polariton - was found. Our results reveal a new class of magnetic\nsystems where strong coupling of microwave photons to non-trivial spin textures\ncan be observed.",
        "positive": "Resonantly exited precession motion of three-dimensional vortex core in\n  magnetic nanospheres: We found resonantly excited precession motions of a three-dimensional vortex\ncore in soft magnetic nanospheres and controllable precession frequency with\nthe sphere diameter 2R, as studied by micromagnetic numerical and analytical\ncalculations. The precession angular frequency for an applied static field\n$H_{DC}$ is given as $\\omega_{MV}= \\gamma_{eff} H_{DC}$, where $\\gamma_{eff} =\n\\gamma <m_{\\Gamma}>$ is the effective gyromagnetic ratio in collective vortex\ndynamics, with the gyromagnetic ratio $\\gamma$ and the average magnetization\ncomponent $<m_{\\Gamma}>$ of the ground-state vortex in the core direction.\nFitting to the micromagnetic simulation data for $<m_{\\Gamma}>$ yields a simple\nexplicit form of $<m_{\\Gamma}> = (73.6 \\pm 3.4)(l_{ex}/2R)^{2.20 \\pm 0.14}$,\nwhere $l_{ex}$ is the exchange length of a given material. This dynamic\nbehavior might serve as a foundation for potential bio-applications of\nsize-specific resonant excitation of magnetic vortex-state nanoparticles, for\nexample, magnetic particle resonance imaging."
    },
    {
        "anchor": "Phonon-induced exciton weak localization in two-dimensional\n  semiconductors: We study theoretically the contribution of quantum effects to the exciton\ndiffusion coefficient in atomically thin crystals. It is related to the weak\nlocalization caused by the interference of excitonic wavefunctions on the\ntrajectories with closed loops. Due to a weak inelasticity of the\nexciton-phonon interaction the effect is present even if the excitons are\nscattered by long-wavelength acoustic phonons. We consider exciton interaction\nwith longitudinal acoustic phonons with linear dispersion and with flexural\nphonons with quadratic dispersion. We identify the regimes where the weak\nlocalization effect can be particularly pronounced. We also briefly address the\nrole of free charge carriers in the exciton quantum transport and, within the\nself-consistent theory of localization, the weak localization effects beyond\nthe lowest order.",
        "positive": "Roughness correction to the Casimir force at short separations: Contact\n  distance and extreme value statistics: So far there has been no reliable method to calculate the Casimir force at\nseparations comparable to the root-mean-square of the height fluctuations of\nthe surfaces. Statistical analysis of rough gold samples has revealed the\npresence of peaks considerably higher than the root-mean-square roughness.\nThese peaks redefine the minimum separation distance between the bodies and can\nbe described by extreme value statistics. Here we show that the contribution of\nthe high peaks to the Casimir force can be calculated with a pairwise additive\nsummation, while the contribution of asperities with normal height can be\nevaluated perturbatively. This method provides a reliable estimate of the\nCasimir force at short distances, and it solves the significant, so far\nunexplained discrepancy between measurements of the Casimir force between rough\nsurfaces and the results of perturbation theory. Furthermore, we illustrate the\nimportance of our results in a technologically relevant situation."
    },
    {
        "anchor": "Nuclear spin relaxation mediated by donor-bound and free electrons in\n  wide CdTe quantum wells: The nuclear spin systems in CdTe/(Cd,Zn)Te and CdTe/(Cd,Mg)Te quantum wells\n(QW) are studied using a multistage technique combining optical pumping and\nHanle effect-based detection. The samples demonstrate drastically different\nnuclear spin dynamics in zero and weak magnetic fields. In CdTe/(Cd,Zn)Te, the\nnuclear spin relaxation time is found to strongly increase with the magnetic\nfield, growing from 3 s in zero field to tens of seconds in a field of 25 G. In\nCdTe/(Cd,Mg)Te the relaxation is an order of magnitude slower, and it is\nfield-independent up to at least 70 G. The differences are attributed to the\nnuclear spin relaxation being mediated by different kinds of resident electrons\nin these QWs. In CdTe/(Cd,Mg)Te, a residual electron gas trapped in the QW\nlargely determines the relaxation dynamics. In CdTe/(Cd,Zn)Te, the fast\nrelaxation in zero field is due to interaction with localized donor-bound\nelectrons. Nuclear spin diffusion barriers form around neutral donors when the\nexternal magnetic field exceeds the local nuclear field, which is about\n$B_L\\approx $0.4 G in CdTe. This inhibits nuclear spin diffusion towards the\ndonors, slowing down relaxation. These findings are supported by theoretical\nmodeling. In particular, we show that the formation of the diffusion barrier is\nmade possible by several features specific to CdTe: (i) the large donor binding\nenergy (about 10 meV), (ii) the low abundance of magnetic isotopes (only\n$\\approx$30% of nuclei have nonzero spin), and (iii) the absence of nuclear\nquadrupole interactions between nuclei. The two latter properties are also\nfavorable to nuclear spin cooling via optical pumping followed by adiabatic\ndemagnetization. Under non-optimized conditions we have reached sub-microkelvin\nnuclear spin temperatures in both samples, lower than all previous results\nobtained in GaAs.",
        "positive": "Role of Single Defects in Electronic Transport through Carbon Nanotube\n  Field-Effect Transistors: The influence of defects on electron transport in single-wall carbon nanotube\nfield effect transistors (CNFETs) is probed by combined scanning gate\nmicroscopy (SGM) and scanning impedance microscopy (SIM). SGM reveals a\nlocalized field effect at discrete defects along the CNFET length. The\ndepletion surface potential of individual defects is quantified from the\nSGM-imaged radius of the defect as a function of tip bias voltage. This\nprovides a measure of the Fermi level at the defect with zero tip voltage,\nwhich is as small as 20 meV for the strongest defects. The effect of defects on\ntransport is probed by SIM as a function of backgate and tip-gate voltage. When\nthe backgate voltage is set so the CNFET is \"on\" (conducting), SIM reveals a\nuniform potential drop along its length, consistent with diffusive transport.\nIn contrast, when the CNFET is \"off\", potential steps develop at the position\nof depleted defects. Finally, high-resolution imaging of a second set of weak\ndefects is achieved in a new \"tip-gated\" SIM mode."
    },
    {
        "anchor": "Intrinsic Perturbation of the Landau Levels in Metals and Semiconductors\n  at Low Temperatures: It is shown that the frequency of the de Haas van Alphen effect in\nnonsuperconducting metals at very low temperatures is significantly corrected\nby a perturbative term which appears in the Landau equation sequel to an\nextension of the Pauli equation. The correction to the frequency of the de Haas\nvan Alphen oscillations is found to depend on the Fermi energy and the\nmeasurable anomalous part of the electron gyro-magnetic factor. Furthermore, it\nis shown that as a consequence of the perturbing term the electronic specific\nheat Cv of a dilute, degenerate Fermi gas, under high magnetic field induction\ngreater that 25 Tesla and at ultra-low temperatures of the order of one milli\nKelvin shows an anomalous behavior, and at a finite temperature becomes\nvanishingly small, i.e Cv is approximately zero, as the temperature approaches\nabsolute zero. Precision measurement at low temperatures and high magnetic\nfields of the magneto optical absorption in simple band semiconductors is\nsuggested as an immediate way of detecting the modification of the Landau\nlevels due to the weak perturbation term which corrects in a magnetic field,\nthe kinetic energy of the electrons.",
        "positive": "Surface induced electronic Berry curvature in Berry curvature free bulk\n  materials: In recent years it has become clear that electronic Berry curvature (BC) is a\nkey concept to understand and predict physical properties of crystalline\nmaterials. A wealth of interesting Hall-type responses in charge, spin and heat\ntransport are caused by the BC associated to electronic bands inside a solid:\nanomalous Hall effects in magnetic materials, and various nonlinear Hall and\nNernst effects in non-magnetic systems that lack inversion symmetry. However,\nfor the largest class of known materials -- non-magnetic ones with inversion\nsymmetry -- electronic BC is strictly zero. Here we show that precisely for\nthese bulk BC-free materials, a finite BC can emerge at their surfaces and\ninterfaces. This immediately activates certain surfaces in producing Hall-type\ntransport responses. We demonstrate this by first principles calculations of\nthe BC at bismuth, mercury-telluride (HgTe) and rhodium surfaces of various\nsymmetries, revealing the presence of a surface Berry curvature dipole and\nassociated quantum nonlinear Hall effects at a number of these. This opens up a\nplethora of materials to explore and harness the physical effects emerging from\nthe electronic Berry curvature associated exclusively to their boundaries."
    },
    {
        "anchor": "Extrinsic spin Nernst effect in two-dimensional electron systems: The spin accumulation due to the spin current induced by the perpendicular\ntemperature gradient (the spin Nernst effect) is studied in a two-dimensional\nelectron system (2DES) with spin-orbit interaction by employing the Boltzmann\nequation. The considered 2DES is confined within a symmetric quantum well with\ndelta doping at the center of the well. A symmetry consideration leads to the\nspin-orbit interaction which is diagonal in the spin component perpendicular to\nthe 2DES. As origins of the spin current, the skew scattering and the side jump\nare considered at each impurity on the center plane of the well. It is shown\nthat, for repulsive impurity potentials, the spin-Nernst coefficient changes\nits sign at the impurity density where contributions from the skew scattering\nand the side jump cancel each other out. This is in contrast to the spin Hall\neffect in which the sign change of the coefficient occurs for attractive\nimpurity potentials.",
        "positive": "First-Principles Simulations of Inelastic Electron Tunneling\n  Spectroscopyof Molecular Junctions: A generalized Green's function theory is developed to simulate the inelastic\nelectron tunneling spectroscopy (IETS) of molecular junctions. It has been\napplied to a realistic molecular junction with an octanedithiolate embedded\nbetween two gold contacts in combination with the hybrid density functional\ntheory calculations. The calculated spectra are in excellent agreement with\nrecent experimental results. Strong temperature dependence of the experimental\nIETS spectra is also reproduced. It is shown that the IETS is extremely\nsensitive to the intra-molecular conformation and to the molecule-metal contact\ngeometry."
    },
    {
        "anchor": "Herzberg Circuit and Berry's Phase in Chirality-based Coded Qubit in a\n  Triangular Triple Quantum Dot: We present a theoretical proposal for the Herzberg circuit and controlled\naccumulation of Berry's phase in a chirality-based coded qubit in a triangular\ntriple quantum dot molecule with one electron spin each. The qubit is encoded\nin the two degenerate states of a three spin complex with total spin $S=1/2$.\nUsing a Hubbard and Heisenberg model the Herzberg circuit encircling the\ndegeneracy point is realized by adiabatically tuning the successive on-site\nenergies of quantum dots and tunnel couplings across a pair of neighbouring\ndots. It is explicitly shown that encircling the degeneracy point leads to the\naccumulation of the geometrical Berrys phase. We show that only triangular but\nnot linear quantum dot molecule allows for the generation of Berry's phase and\nwe discuss a protocol to detect this geometrical phase.",
        "positive": "Higgs and Goldstone spin-wave modes in striped magnetic texture: Spontaneous symmetry breaking is ubiquitous in physics. Its spectroscopic\nsignature consists in the softening of a specific mode upon approaching the\ntransition from the high symmetry side and its subsequent splitting into a\nzero-frequency \"Goldstone\" mode and a non-zero-frequency \"Higgs\" mode. Although\nthey determine the whole system dynamics, these features are difficult to\naddress in practice because of their vanishing coupling to most experimental\nprobes and/or their strong interaction with other fluctuations. In this work,\nwe consider a periodic magnetic modulation occurring in a ferromagnetic film\nwith perpendicular-to-plane magnetic anisotropy and directly observe its\nGoldstone and Higgs spin-wave modes at room temperature using microwave and\noptical techniques. This simple system constitutes a particularly convenient\nplatform for further exploring the dynamics of symmetry breaking."
    },
    {
        "anchor": "Supersymmetry in carbon nanotubes in a transverse magnetic field: Electron properties of Carbon nanotubes in a transverse magnetic field are\nstudied using a model of a massless Dirac particle on a cylinder. The problem\npossesses supersymmetry which protects low energy states and ensures stability\nof the metallic behavior in arbitrarily large fields. In metallic tubes we find\nsuppression of the Fermi velocity at half-filling and enhancement of the\ndensity of states. In semiconducting tubes the energy gap is suppressed. These\nfeatures qualitatively persist (although to a smaller degree) in the presence\nof electron interactions. The possibilities of experimental observation of\nthese effects are discussed.",
        "positive": "Effects of surface plasmons on spin currents in a thin film system: We propose and analyze surface-plasmon-driven electron spin currents in a\nthin metallic film. The electron gas in the metal follows the transversally\nrotating electric fields of the surface plasmons (SPs), which leads to a static\nmagnetization gradient. We consider herein SPs in a thin-film\ninsulator-metal-insulator structure and solve the spin diffusion equation in\nthe presence of a magnetization gradient. The results reveal that the SPs at\nthe metal interfaces generate spin currents in the metallic film. For thinner\nfilm, the SPs become strongly hybridized, which increases the magnetization\ngradient and enhances the spin current. We also discuss how the spin current\ndepends on SP wavelength and the spin-diffusion length of the metal. The\npolarization of the spin current can be controlled by tuning the wavelength of\nthe SPs and/or the spin diffusion length."
    },
    {
        "anchor": "Geometrical Pumping in Quantum Transport: Quantum Master Equation\n  Approach: For an open quantum system, we investigate the pumped current induced by a\nslow modulation of control parameters on the basis of the quantum master\nequation and full counting statistics. We find that the average and the\ncumulant generating function of the pumped quantity are characterized by the\ngeometrical Berry-phase-like quantities in the parameter space, which is\nassociated with the generator of the master equation. From our formulation, we\ncan discuss the geometrical pumping under the control of the chemical\npotentials and temperatures of reservoirs. We demonstrate the formulation by\nspinless electrons in coupled quantum dots. We show that the geometrical\npumping is prohibited for the case of non-interacting electrons if we modulate\nonly temperatures and chemical potentials of reservoirs, while the geometrical\npumping occurs in the presence of an interaction between electrons.",
        "positive": "Flat bands with non-trivial topology in three dimensions: We construct a simple model for electrons in a three-dimensional crystal\nwhere a combination of short-range hopping and spin-orbit coupling results in\nnearly flat bands characterized by a non-trivial Z2 topological index. The flat\nband is separated from other bands by a bandgap much larger than the bandwidth.\nWe discuss the fate of the many-body ground state of electrons in the flat band\nin the presence of repulsive interactions at partial filling and conjecture\nthat it may become a three-dimensional fractional topological insulator if\nconventional magnetic instabilities can be avoided."
    },
    {
        "anchor": "Superconducting proximity effect in interacting double-dot systems: We study subgap transport from a superconductor through a double quantum dot\nwith large on-site Coulomb repulsion to two normal leads. Non-local\nsuperconducting correlations in the double dot are induced by the proximity to\nthe superconducting lead, detectable in non-local Andreev transport that splits\nCooper pairs in locally separated, spin-entangled electrons. We find that the\n$I$--$V$ characteristics are strongly asymmetric: for a large bias voltage of\ncertain polarity, transport is blocked by populating the double dot with states\nwhose spin symmetry is incompatible with the superconductor. Furthermore, by\ntuning gate voltages one has access to splitting of the Andreev excitation\nenergies, which is visible in the differential conductance.",
        "positive": "Quantized invariant tori in Andreev billiards of mixed phase space: Comparing the results of exact quantum calculations and those obtained from\nthe EBK-like quantization scheme of Silvestrov et al [Phys. Rev. Lett. 90,\n116801 (2003)] we show that the spectrum of Andreev billiards of mixed phase\nspace can basically be decomposed into a regular and an irregular part,\nsimilarly to normal billiards. We provide the first numerical confirmation of\nthe validity of this quantization scheme for individual eigenstates and discuss\nits accuracy."
    },
    {
        "anchor": "Theory of nonlinear microwave absorption by interacting two-level\n  systems: The microwave absorption and noise caused by quantum two-level systems (TLS)\ndramatically suppress the coherence in Josephson junction qubits that are\npromising candidates for a quantum information applications. Microwave\nabsorption by TLSs is not clearly understood yet because of the complexity of\ntheir interactions leading to the spectral diffusion. Here, the theory of the\nnon-linear absorption in the presence of spectral diffusion is developed using\nthe generalized master equation formalism. The theory predicts that the linear\nabsorption regime holds while a TLS Rabi frequency is smaller than their phase\ndecoherence rate. At higher external fields, a novel non-linear absorption\nregime is found with the loss tangent inversely proportional to the intensity\nof the field. The theory can be generalized to acoustic absorption and lower\ndimensions realized in superconducting qubits.",
        "positive": "Conductance through disordered graphene nanoribbons: Standard and\n  anomalous electron localization: Conductance fluctuations produced by the presence of disorder in zigzag and\narmchair graphene nanoribbons are studied. We show that quantum transport in\nzigzag nanoribbons takes place via edge states which are exponentially\nlocalized, as in the standard Anderson localization problem, whereas for\narmchair nanoribbons the symmetry of the graphene sublattices produces\nanomalous localization, or delocalization. We show that these two different\nelectron localizations lead to significant differences of the conductance\nstatistics between zigzag and armchair nanoribbons. In particular, armchair\nnanoribbons show nonconventional large conductance fluctuations relative to\nthose of Anderson-localized electrons. We calculate analytically the complete\ndistribution of conductances for both types of ribbons. Without free fitting\nparameters, we verify our theoretical results by performing numerical\nsimulations of disordered zigzag and armchair nanoribbons of experimentally\nachievable lengths and widths."
    },
    {
        "anchor": "Equilibration and Filtering of Quantum Hall Edge States in Few-Layer\n  Black Phosphorus: We realize p-p'-p junctions in few-layer black phosphorus (BP) devices, and\nuse magneto-transport measurements to study the equilibration and transmission\nof edge states at the interfaces of regions with different charge densities. We\nobserve both full equilibration, where all edge channels equilibrate and are\nequally partitioned at the interfaces, and partial equilibration, where only\nequilibration only takes place among modes of the same spin polarization.\nFurthermore, the inner p'-region with low-doping level in the junction can\nfunction as a filter for highly doped p-regions which demonstrates gate-tunable\ntransmission of edge channels.",
        "positive": "Photoelectrical detection of electron spin resonance of nitrogen-vacancy\n  centres in diamond: The protocols for the control and readout of Nitrogen Vacancy (NV) centres\nelectron spins in diamond offer an advanced platform for quantum computation,\nmetrology and sensing. These protocols are based on the optical readout of\nphotons emitted from NV centres, which process is limited by the yield of\nphotons collection. Here we report on a novel principle for the detection of NV\ncentres magnetic resonance in diamond by directly monitoring spin-preserving\nelectron transitions through measurement of NV centre related photocurrent. The\ndemonstrated direct detection technique offers a sensitive way for the readout\nof diamond NV sensors and diamond quantum devices on diamond chips. The\nPhotocurrent Detection of Magnetic Resonance (PDMR) scheme is based on the\ndetection of charge carriers promoted to the conduction band of diamond by the\ntwo-photon ionization of NV- centres. Optical detection of magnetic resonance\n(ODMR) and PDMR are compared, by performing both measurements simultaneously.\nThe minima detected in the measured photocurrent at resonant microwave\nfrequencies are attributed to the spin-dependent occupation probability of the\nNV- ground state, originating from spin-selective non-radiative transitions."
    },
    {
        "anchor": "Valley-selective energy transfer between quantum dots in atomically thin\n  semiconductors: In monolayers of transition metal dichalcogenides the nonlocal nature of the\neffective dielectric screening leads to large binding energies of excitons.\nAdditional lateral confinement gives rise to exciton localization in quantum\ndots. By assuming parabolic confinement for both the electron and the hole, we\nderive model wave functions for the relative and the center-of-mass motions of\nelectron-hole pairs, and investigate theoretically resonant energy transfer\namong excitons localized in two neighboring quantum dots. We quantify the\nprobability of energy transfer for a direct-gap transition by assuming that the\ninteraction between two quantum dots is described by a Coulomb potential, which\nallows us to include all relevant multipole terms of the interaction. We\ndemonstrate the structural control of the valley-selective energy transfer\nbetween quantum dots.",
        "positive": "Surface plasmon polaritons assisted diffraction in periodic\n  subwavelength holes of metal films with reduced interplane coupling: Metal films grown on Si wafer perforated with a periodic array of\nsubwavelength holes have been fabricated and anomalous enhanced transmission in\nthe mid-infrared regime has been observed. High order transmission peaks up to\nSi(2,2) are clearly revealed due to the large dielectric constant contrast of\nthe dielectrics at the opposite interfaces. Si(1,1) peak splits at oblique\nincidence both in TE and TM polarization, which confirms that anomalous\nenhanced transmission is a surface plasmon polaritons (SPPs) assisted\ndiffraction phenomenon. Theoretical transmission spectra agree excellently with\nthe experimental results and confirm the role of SPPs diffraction by the\nlattice."
    },
    {
        "anchor": "Electron-induced limitation of surface plasmon propagation in silver\n  nanowires: Plasmonic circuitry is considered as a promising solution-effective\ntechnology for miniaturizing and integrating the next generation of optical\nnano-devices. A key element is the shared metal network between electrical and\noptical information enabling an efficient hetero-integration of an electronic\ncontrol layer and a plasmonic data link. Here, we investigate to what extend\nsurface plasmons and current-carrying electrons interfere in such a shared\ncircuitry. By synchronously recording surface plasmon propagation and\nelectrical output characteristics of single chemically-synthesized silver\nnanowires we determine the limiting factors hindering the co-propagation of\nelectrical current and surface plasmons in these nanoscale circuits.",
        "positive": "Theoretical Study of New Acceptor and Donor Molecules based on\n  Polycyclic Aromatic Hydrocarbons: Functionalized polcyclic aromatic hydrocarbons (PAHs) are an interesting\nclass of molecules in which the electronic state of the graphene-like\nhydrocarbon part is tuned by the functional group. Searching for new types of\ndonor and acceptor molecules, a set of new PAHs has recently been investigated\nexperimentally using ultraviolet photoelectron spectroscopy (UPS). In this\nwork, the electronic structure of the PAHs is studied numerically with the help\nof B3LYP hybrid density functionals. Using the DELTA-SCF method, electron\nbinding energies have been determined which affirm, specify and complement the\nUPS data. Symmetry properties of molecular orbitals are analyzed for a\ncategorization and an estimate of the related signal strength. While SIGMA-like\norbitals are difficult to detect in UPS spectra of condensed film, calculation\nprovides a detailed insight into the hidden parts of the electronic structure\nof donor and acceptor molecules. In addition, a diffuse basis set (6-311++G**)\nwas used to calculate electron affinity and LUMO eigenvalues. The calculated\nelectron affinity (EA) provides a classification of the donor/acceptor\nproperties of the studied molecules. Coronene-hexaone shows a high EA,\ncomparable to TCNQ, which is a well-known classical acceptor. Calculated\nHOMO-LUMO gaps using the related eigenvalues have a good agreement with the\nexperimental lowest excitation energies. TD-DFT also accurately predicts the\nmeasured optical gap."
    },
    {
        "anchor": "About the two spin-channel model for ferromagnetic excitations and\n  spin-dependent heat transfer equations: The two spin-channel model is generalized to the case of transport of\nferromagnetic excitations in electric conductors and insulators. The two\nchannels are defined by reducing the ferromagnetic degrees of freedom to a\nbivaluated variable, i.e. to an effective spin one-half. The reduction is\nperformed after defining the local magnetic configuration space by a sphere\n$\\Sigma_x$, and integrating the relevant physical quantities over the two\nhemispheres $\\Sigma_x^{\\uparrow}$ and $\\Sigma_x^{\\downarrow}$. The\nconfiguration space is then extended to the $x$ direction for non-uniform\nmagnetization excitations. The transport equations for both magnetic moments\nand magnetic energy are deduced, including the relaxation from one channel to\nthe other. The heat transport equations for ferromagnets is deduced.",
        "positive": "Graphene microbolometers with superconducting contacts for terahertz\n  photon detection: We report on noise and thermal conductance measurements taken in order to\ndetermine an upper bound on the performance of graphene as a terahertz photon\ndetector. The main mechanism for sensitive terahertz detection in graphene is\nbolometric heating of the electron system. To study the properties of a device\nusing this mechanism to detect terahertz photons, we perform Johnson noise\nthermometry measurements on graphene samples. These measurements probe the\nelectron-phonon behavior of graphene on silicon dioxide at low temperatures.\nBecause the electron-phonon coupling is weak in graphene, superconducting\ncontacts with large gap are used to confine the hot electrons and prevent their\nout-diffusion. We use niobium nitride leads with a $T_\\mathrm{c}\\approx 10$ K\nto contact the graphene. We find these leads make good ohmic contact with very\nlow contact resistance. Our measurements find an electron-phonon thermal\nconductance that depends quadratically on temperature above 4 K and is\ncompatible with single terahertz photon detection."
    },
    {
        "anchor": "Enhancement-mode buried strained silicon channel quantum dot with\n  tunable lateral geometry: We propose and demonstrate a relaxed-SiGe/strained-Si (SiGe/s-Si)\nenhancement-mode gate stack for quantum dots. The enhancement-mode SiGe/s-Si\nstructure is pursued because it spaces the quantum dot away from charge and\nspin defect rich dielectric interfaces and minimizes background dopants. A\nmobility of 1.6\\times10^5 cm^2/Vs at 5.8\\times10^{11}/cm^2 is measured in Hall\nbars that witness the same device process flow as the quantum dot. Periodic\nCoulomb blockade (CB) is measured in a double-top-gated lateral quantum dot\nnanostructure. The CB terminates with open diamonds up to \\pm 10 mV of DC\nvoltage across the device. The devices were fabricated within a 150 mm Si\nfoundry setting that uses implanted ohmics and chemical-vapor-deposited\ndielectrics, in contrast to previously demonstrated enhancement-mode SiGe/s-Si\nstructures made with AuSb alloyed ohmics and atomic-layer-deposited dielectric.\nA modified implant, polysilicon formation and annealing conditions were\nutilized to minimize the thermal budget so that the buried s-Si layer would not\nbe washed out by Ge/Si interdiffusion.",
        "positive": "Imaging the potential distribution of individual charged impurities on\n  graphene by low-energy electron holography: While imaging individual atoms can routinely be achieved in high resolution\ntransmission electron microscopy, visualizing the potential distribution of\nindividually charged adsorbates leading to a phase shift of the probing\nelectron wave is still a challenging task. Low-energy electrons (30 - 250 eV)\nare sensitive to localized potential gradients. We employed low-energy electron\nholography to acquire in-line holograms of individual charged impurities on\nfree-standing graphene. By applying an iterative phase retrieval reconstruction\nroutine we recover the potential distribution of the localized charged\nimpurities present on free-standing graphene."
    },
    {
        "anchor": "Current-induced magnetoresistance oscillations in two-dimensional\n  electron systems: Electric current-induced magnetoresistance oscillations recently discovered\nin two-dimensional electron systems are analyzed using a microscopic scheme for\nnonlinear magnetotransport direct controlled by the current. The\nmagnetoresistance oscillations are shown to result from drift-motion assisted\nelectron scatterings between Landau levels. The theoretical predictions not\nonly reproduce all the main features observed in the experiments but also\ndisclose other details of the phenomenon.",
        "positive": "Spin-polarized transport properties in magnetic moir\u00e9 superlattices: Since the discovery of the fascinating properties in magic-angle graphene,\nthe exploration of moir\\'e systems in other two-dimensional materials has\ngarnered significant attention and given rise to a field known as 'moir\\'e\nphysics'. Within this realm, magnetic van der Waals heterostructure and the\nmagnetic proximity effect in moir\\'e superlattices have also become subjects of\ngreat interest. However, the spin-polarized transport property in this moir\\'e\nstructures is still a problem to be explored. Here, we investigate the\nspin-polarized transport properties in a moir\\'e superlattices formed by a\ntwo-dimensional ferromagnet CrI_3 stacked on a monolayer BAs, where the spin\ndegeneracy is lifted because of the magnetic proximity effect associated with\nthe moir\\'e superlattices. We find that the conductance exhibits spin-resolved\nminiband transport properties at a small twist angle because of the periodic\nmoir\\'e superlattices. When the incident energy is in the spin-resolved\nminigaps, the available states are spin polarized, thus providing a\nspin-polarized current from the superlattice. Moreover, only a finite number of\nmoir\\'e period is required to obtain a net spin polarization of 100\\%. In\naddition, the interlayer distance of the heterojunction is also moir\\'e\nmodifiable, so a perpendicular electric field can be applied to modulate the\nintensity and direction of the spin polarization. Our finding points to an\nopportunity to realize spin functionalities in magnetic moir\\'e superlattices."
    },
    {
        "anchor": "Layer degree of freedom for excitons in transition metal dichalcogenides: Layered transition metal dichalcogenides (TMDCs) host a variety of strongly\nbound exciton complexes that control the optical properties in these materials.\nApart from spin and valley, layer index provides an additional degree of\nfreedom in a few-layer thick film. Here we show that in a few-layer TMDC film,\nthe wavefunctions of the conduction and valence band edge states contributing\nto the K (K') valley are spatially confined in the alternate layers - giving\nrise to direct (quasi-)intra-layer bright exciton and lower-energy inter-layer\ndark excitons. Depending on the spin and valley configuration, the bright\nexciton state is further found to be a coherent superposition of two\nlayer-induced states, one (E-type) distributed in the even layers and the other\n(O-type) in the odd layers. The intra-layer nature of the bright exciton\nmanifests as a relatively weak dependence of the exciton binding energy on the\nthickness of the few-layer film, and the binding energy is maintained up to 50\nmeV in the bulk limit - which is an order of magnitude higher than conventional\nsemiconductors. Fast stokes energy transfer from the intra-layer bright state\nto the inter-layer dark states provides a clear signature in the\nlayer-dependent broadening of the photoluminescence peak, and plays a key role\nin the suppression of the photoluminescence intensity observed in TMDCs with\nthickness beyond monolayer.",
        "positive": "High-fidelity conformation of graphene to SiO2 topographic features: Strain engineering of graphene through interaction with a patterned substrate\noffers the possibility of tailoring its electronic properties, but will require\ndetailed understanding of how graphene's morphology is determined by the\nunderlying substrate. However, previous experimental reports have drawn\nconflicting conclusions about the structure of graphene on SiO2. Here we show\nthat high-resolution non-contact atomic force microscopy of SiO2 reveals\nroughness at the few-nm length scale unresolved in previous measurements, and\nscanning tunneling microscopy of graphene on SiO2 shows it to be slightly\nsmoother than the supporting SiO2 substrate. Quantitative analysis of the\ncompetition between bending rigidity of the graphene and adhesion to the\nsubstrate explains the observed roughness of monolayer graphene on SiO2 as\nextrinsic, and provides a natural, intuitive description in terms of highly\nconformal adhesion. The analysis indicates that graphene adopts the\nconformation of the underlying substrate down to the smallest features with\nnearly 99% fidelity."
    },
    {
        "anchor": "Electronic structure, spin-orbit coupling, and interlayer interaction in\n  bulk MoS2 and WS2: We present in-depth measurements of the electronic band structure of the\ntransition-metal dichalcogenides (TMDs) MoS2 and WS2 using angle-resolved\nphotoemission spectroscopy, with focus on the energy splittings in their\nvalence bands at the K point of the Brillouin zone. Experimental results are\ninterpreted in terms of our parallel first-principles computations. We find\nthat interlayer interaction only weakly contributes to the splitting in bulk\nWS2, resolving previous debates on its relative strength. We additionally find\nthat across a range of TMDs, the band gap generally decreases with increasing\nmagnitude of the valence-band splitting, molecular mass, or ratio of the\nout-of-plane to in-plane lattice constant. Our results provide an important\nreference for future studies of electronic properties of MoS2 and WS2 and their\napplications in spintronics and valleytronics devices.",
        "positive": "Thermodynamics of Energy Magnetization: We construct the thermodynamics of energy magnetization in the presence of\ngravitomagnetic field. We show that the free energy must be modified to account\nfor the modification of the energy current operator in the presence of a\nconfining potential. The explicit expression of the energy magnetization is\nderived for a periodic system, and the Streda formula for the thermal Hall\nconductivity is rigorously established. We demonstrate our theory of the energy\nmagnetization and the Streda formula in a Chern insulator."
    },
    {
        "anchor": "Boundaries of Subcritical Coulomb Impurity Region in Gapped Graphene: The electronic energy spectrum of graphene electron subjected to a\nhomogeneous magnetic field in the presence of a charged Coulomb impurity is\nstudied analytically within two-dimensional Dirac-Weyl picture by using\nvariational approach. The variational scheme we used is just based on utilizing\nthe exact eigenstates of two-dimensional Dirac fermion in the presence of a\nuniform magnetic field as a basis for determining analytical energy eigenvalues\nin the presence of an attractive/repulsive charged Coulomb impurity. This\napproach allows us to determine under which conditions bound state solutions\ncan or can not exist in gapped graphene in the presence of magnetic field. In\naddition, the effects of uniform magnetic field on the boundaries of\nsubcritical Coulomb impurity region in the massless limit are also analyzed.\nOur analytical results show that the critical impurity strength decreases with\nincreasing gap/mass parameter, and also that it increases with increasing\nmagnetic field strength. In the massless limit, we investigate that the\ncritical Coulomb coupling strength is independent of magnetic field, and its\nupper value for the ground-state energy is 0.752.",
        "positive": "Quantum Plasmonic Nanoantennas: We study plasmonic excitations in the limit of few electrons, in one-atom\nthick sodium chains, and characterize them based on collectivity. We also\ncompare the excitations to classical localised plasmon modes and find for the\nlongitudinal mode a quantum-classical transition around 10 atoms. The\ntransverse mode appears at much higher energies than predicted classically for\nall chain lengths. The electric field enhancement is also considered which is\nmade possible by considering the effects of electron-phonon coupling on the\nbroadening of the electronic spectra. Large field enhancements are possible on\nthe molecular level allowing us to consider the validity of using molecules as\nthe ultimate small size limit of plasmonic antennas. Additionally, we consider\nthe case of a dimer system of two sodium chains, where the gap can be\nconsidered as a picocavity, and we analyse the charge-transfer states and their\ndependence on the gap size as well as chain size. Our results and methods are\nuseful for understanding and developing ultra-small, tunable and novel\nplasmonic devices that utilise quantum effects that could have applications in\nquantum optics, quantum metamaterials, cavity-quantum electrodynamics and\ncontrolling chemical reactions, as well as deepening our understanding of\nlocalised plasmons in low dimensional molecular systems."
    },
    {
        "anchor": "Influence of the Surface Structure and Vibration Mode on the Resistivity\n  of Cu Films: The influence of the surface structure and vibration mode on the resistivity\nof Cu films and the corresponding size effect are investigated. The temperature\ndependent conductivities of the films with different surface morphologies are\ncalculated by the algorithm based upon the tight-binding linear muffin-tin\norbital method and the Green's function technique. The thermal effect is\nintroduced by setting the atomic displacements according to the Gaussian\ndistribution with the mean-square amplitude estimated by the Debye model. The\nresult shows that the surface atomic vibration contributes significantly to the\nresistivity of the systems. Comparing the conductivities for three different\nvibration modes, it is suggested that freezing the surface vibration is\nnecessary for practical applications to reduce the resistivity induced by the\nsurface electron-phonon scattering.",
        "positive": "Endstates in multichannel spinless p-wave superconducting wires: Multimode spinless p-wave superconducting wires with a width W much smaller\nthan the superconducting coherence length \\xi are known to have multiple\nlow-energy subgap states localized near the wire's ends. Here we compare the\ntypical energies of such endstates for various terminations of the wire: A\nsuperconducting wire coupled to a normal-metal stub, a weakly disordered\nsuperconductor wire and a wire with smooth confinement. Depending on the\ntermination, we find that the energies of the subgap states can be higher or\nlower than for the case of a rectangular wire with hard-wall boundaries."
    },
    {
        "anchor": "Coulomb correlations of a few body system of spatially separated charges: A Hartree-Fock and Hartree-Fock-Bogoliubov study of a few body system of\nspatially separated charge carriers was carried out. Using these variational\nstates, we compute an approximation to the correlation energy of a finite\nsystem of electron-hole pairs. This energy is shown as a function of the\nCoulomb coupling and the interplane distance. We discuss how the correlation\nenergy can be used to theoretically determine the formation of indirect\nexcitons in semiconductors which is relevant for collective phenomena such as\nBose-Einstein condensation (BEC).",
        "positive": "Spin wave vortex from the scattering on Bloch point solitons: The interaction of a spin wave with a stationary Bloch point is studied. The\ntopological non-trivial structure of the Bloch point manifests in the\npropagation of spin waves endowing them with a gauge potential that resembles\nthe one associated with the interaction of a magnetic monopole and an electron.\nBy pursuing this analogy, we are led to the conclusion that the scattering of\nspin waves and Bloch points is accompanied by the creation of a magnon vortex.\nInterference between such a vortex and a plane wave leads to dislocations in\nthe interference pattern that can be measurable by means of magnon holography."
    },
    {
        "anchor": "Simultaneous Optical and Electrical Spin-Torque Magnetometry with\n  Stroboscopic Detection of Spin-Precession Phase: Spin-based coherent information processing and encoding utilize the\nprecession phase of spins in magnetic materials. However, the detection and\nmanipulation of spin precession phases remain a major challenge for advanced\nspintronic functionalities. By using simultaneous electrical and optical\ndetection, we demonstrate the direct measurement of the precession phase of\nPermalloy ferromagnetic resonance driven by the spin-orbit torques from\nadjacent heavy metals. The spin Hall angle of the heavy metals can be\nindependently determined from concurrent electrical and optical signals. The\nstroboscopic optical detection also allows spatially measuring local\nspin-torque parameters and the induced ferromagnetic resonance with\ncomprehensive amplitude and phase information. Our study offers a route towards\nfuture advanced characterizations of spin-torque oscillators, magnonic\ncircuits, and tunnelling junctions, where measuring the current-induced spin\ndynamics of individual nanomagnets are required.",
        "positive": "Criticality in the Integer Quantum Hall Effect: We review some elementary aspects of the critical properties of the series of\nmetal-insulator transitions that constitute the integer quantum Hall effect.\nNumerical work has proven essential in charting out this phenomenon. Without\nbeing complete, we review network models that seem to capture the essentials of\nthis critical phenomenon."
    },
    {
        "anchor": "Filling factors and Braid group: We extract the Braid group structure of a recently derived hierarchy scheme\nfor the filling factors proposed by us which related the Hausdorff dimension,\n$h$, to statistics, $\\nu$, of the collective excitations in the context of the\nFractional Quantum Hall Effect (FQHE).",
        "positive": "Activated Transport in the individual Layers that form the $\u03bd_T$=1\n  Exciton Condensate: We observe the total filling factor $\\nu_{T}$=1 quantum Hall state in a\nbilayer two-dimensional electron system with virtually no tunnelling. We find\nthermally activated transport in the balanced system with a monotonic increase\nof the activation energy with decreasing $d/\\ell_B$ below 1.65. In the\nimbalanced system we find activated transport in each of the layers separately,\nyet the activation energies show a striking asymmetry around the balance point.\nThis implies that the gap to charge-excitations in the {\\em individual} layers\nis substantially different for positive and negative imbalance."
    },
    {
        "anchor": "Local temperature and chemical potential inside a mesoscopic device\n  driven out of equilibrium: In this paper we introduce a method of calculating the local temperature and\nchemical potential inside a mesoscopic device out of equilibrium. We show how\nto check the conditions of local thermal equilibrium as the whole system is out\nof equilibrium. Especially we study the onsite chemical potentials inside a\nchain coupled to two reservoirs at a finite voltage bias. In the presence of\ndisorder we observe a large fluctuation in onsite chemical potentials, which\ncan be suppressed by the electron-electron interaction. By taking average with\nrespect to the configurations of disorder, we recover the classical picture\nwhere the voltage drops monotonously through the resistance wire. We prove the\nexistence of local intensive variables in a mesoscopic device which is in\nequilibrium or not far from equilibrium.",
        "positive": "Optical read-out of Coulomb staircases in a moir\u00e9 superlattice via\n  trapped interlayer trions: Moir\\'e patterns with a superlattice potential can be formed by vertically\nstacking two layered materials with a relative twist or lattice constant\nmismatch. The moir\\'e superlattice can generate flat bands that result in new\ncorrelated insulating, superconducting, and topological states. Strong electron\ncorrelations, tunable by the fractional filling, have been observed in both\ngraphene and transition metal dichalcogenide (TMD) based systems. In addition,\nin TMD based systems, the moir\\'e potential landscape can trap interlayer\nexcitons (IX) at specific atomic registries. Here we report that spatially\nisolated trapped IX in a molybdenum diselenide/tungsten diselenide\nheterobilayer device provide a sensitive optical probe of carrier filling in\ntheir immediate environment. By mapping the spatial positions of individual\ntrapped IX, we are able to spectrally track the emitters as the moir\\'e lattice\nis filled with excess carriers. Upon initial doping of the heterobilayer,\nneutral trapped IX form charged IX (IX trions) uniformly with a binding energy\nof ~7 meV. Upon further doping, the empty superlattice sites sequentially fill,\ncreating a Coulomb staircase: stepwise changes in the IX trion emission energy\ndue to Coulomb interactions with carriers at nearest neighbour moir\\'e sites.\nThis non-invasive, highly local technique can complement transport and\nnon-local optical sensing techniques to characterise Coulomb interaction\nenergies, visualise charge correlated states, or probe local disorder in a\nmoir\\'e superlattice."
    },
    {
        "anchor": "Quantum correlations of confined exciton-polaritons: Cavity-polaritons in semiconductor microstructures have emerged as a\npromising system for exploring nonequilibrium dynamics of many-body systems.\nKey advances in this field, including the observation of polariton\ncondensation, superfluidity, realization of topological photonic bands, and\ndissipative phase transitions, generically allow for a description based on a\nmean-field Gross-Pitaevskii formalism. While observation of polariton intensity\nsqueezing and decoherence of a polarization entangled photon pair by a\npolariton condensate provide counter-examples, quantum effects in these\nexperiments show up at high polariton occupancy. Going beyond into the regime\nof strongly correlated polaritons requires the observation of a photon blockade\neffect where interactions are strong enough to suppress double occupancy of a\nphotonic lattice site. Here, we report the observation of quantum correlations\nbetween polaritons in a fiber cavity which spatially confines polaritons into\nan area of 3 $\\mu$m$^2$. Photon correlation measurements show that careful\ntuning of the coupled system allows for a modest photon blockade effect as\nevidenced by a reduction of simultaneous two-polariton generation probability\nby 5 %. Concurrently, our experiments provide an unequivocal measurement of the\npolariton interaction strength, thereby resolving the controversy stemming from\nrecent experimental reports. Our findings constitute a first essential step\ntowards the realization of strongly interacting photonic systems.",
        "positive": "Surface plasmon assisted electron pair formation in strong\n  electromagnetic field: The basis of low-temperature superconductivity has been set to be the pair\nformation of electrons, due to their effective attraction. The appearance of an\neffective attraction potential has also been predicted for electron-electron\nscattering in the presence of a strong, inhomogeneous radiation field. In the\npresent work the strong electromagnetic fields were created by femtosecond\nTi:Sa lasers, used to excite surface plasmons in gold films at room\ntemperature, in the Kretschmann geometry. Experimental investigations were\ncarried out using a surface plasmon near-field scanning tunneling microscope,\nby measuring its response to the excitation at hot spots on the gold surface.\nFurthermore, the spectra of photoelectrons, liberated by multi-plasmon\nabsorption, have also been measured by a time-of-flight spectrometer. In both\ncases new type of anomalies in the electon signal have been measured in the\nsame intensity range, whose existence may be qualitatively understood, by using\nthe intensity-dependent expression for the effective electon-electron\nscattering potential, derived earlier in a different context."
    },
    {
        "anchor": "Electrical control of a laterally ordered InAs/InP quantum dash array: We have fabricated an array of closely spaced quantum dashes starting from a\nplanar array of self-assembled semiconductor quantum wires. The array is\nembedded in a metallic nanogap which we investigate by micro-photoluminescence\nas a function of a lateral electric field. We demonstrate that the net electric\ncharge and emission energy of individual quantum dashes can be modified\nexternally with performance limited by the size inhomogeneity of the\nself-assembling process.",
        "positive": "Limits on the Bolometric response of Graphene due to flicker noise: We study the photoresponse of graphene field effect transistors using\nscanning photocurrent microscopy in near and far field configurations, and we\nfind that the response of graphene under a source-drain bias voltage away from\nthe contacts is dominated by the bolometric effect caused by laser induced\nheating. We find no significant change in the photocurrent with the optical\nmodulation frequency upto 100 kHz. Although the magnitude of the bolometric\ncurrent scales with bias voltage, it also results in noise. The frequency\ndependence of this noise indicates that it has a 1/f character, scales with the\nbias voltage and limits the detectable bolometric photoresponse at low optical\npowers."
    },
    {
        "anchor": "Twisted quadrupole topological photonic crystals: Topological manipulation of waves is at the heart of the cutting-edge\nmetamaterial researches. Quadrupole topological insulators were recently\ndiscovered in two-dimensional (2D) flux-threading lattices which exhibit\nhigher-order topological wave trapping at both the edges and corners. Photonic\ncrystals (PhCs), lying at the boundary between continuous media and discrete\nlattices, however, are incompatible with the present quadrupole topological\ntheory. Here, we unveil quadrupole topological PhCs triggered by a twisting\ndegree-of-freedom. Using a topologically trivial PhC as the motherboard, we\nshow that twisting induces quadrupole topological PhCs without flux-threading.\nThe twisting-induced crystalline symmetry enriches the Wannier polarizations\nand lead to the anomalous quadrupole topology. Versatile edge and corner\nphenomena are observed by controlling the twisting angles in a lateral\nheterostructure of 2D PhCs. Our study paves the way toward topological\ntwist-photonics as well as the quadrupole topology in the quasi-continuum\nregime for phonons and polaritons.",
        "positive": "Assisted crystal growing by tempering metastable vapor-liquid fluids: The metastable vapor-liquid coexistence of short-range attractive fluids\nhinders the formation of crystal nuclei, which in turn makes difficult the\nprogress of the system towards its vapor-solid ground state. In this letter we\nshow that crystal growth can be assisted by imposing temperature fluctuations.\nBy so doing the obtained solid is nearly a fcc monocrystal in contrast with the\nextreme polycrystalline structure obtained at low temperatures. The study is\ncarried out by combining the replica exchange Monte Carlo method and the\nstandard slab technique. The obtained results suggest a pathway for growing\ncoherent crystals from the metastable liquid. This is particularly relevant for\nthe crystallization of globular proteins."
    },
    {
        "anchor": "Magnetoelectric torque and edge currents in spin-orbit coupled graphene\n  nanoribbons: For graphene nanoribbons with Rashba spin-orbit coupling, the peculiar\nmagnetic response due to the presence of a magnetization and geometric\nconfinement are analyzed within a tight-binding model. We observe a sizable\ntransverse susceptibility that can be considered as a gate voltage-induced\nmagnetoelectric torque without the need of a bias voltage, with different\ndirections for zigzag and armchair ribbons. The local torque generates\nnon-collinear spin polarization between the two edges and/or along the ribbon,\nand the net torque averages to zero if the magnetization is homogeneous.\nNevertheless, a nonzero net torque can appear in partially magnetized\nnanoribbons or in nanoflakes of irregular shapes. The equilibrium spin current\nproduced by the spin-orbit coupling also appears in nanoribbons, but the\ncomponent flowing in the direction of confinement is strongly suppressed. Even\nwithout the magnetization, an out-of-plane polarized chiral edge spin current\nis produced, resembling that in the quantum spin Hall effect. Moreover, a\nmagnetization pointing perpendicular to the edge produces a laminar flow of\nedge charge currents, whose flow direction is symmetric (non chiral) or\nantisymmetric (chiral) between the two edges depends on whether the\nmagnetization points in-plane or out-of-plane.",
        "positive": "Reversing quantum trajectories with analog feedback: We demonstrate the active suppression of transmon qubit dephasing induced by\ndispersive measurement, using parametric amplification and analog feedback. By\nreal-time processing of the homodyne record, the feedback controller reverts\nthe stochastic quantum phase kick imparted by the measurement on the qubit. The\nfeedback operation matches a model of quantum trajectories with measurement\nefficiency $\\tilde{\\eta} \\approx 0.5$, consistent with the result obtained by\npostselection. We overcome the bandwidth limitations of the amplification chain\nby numerically optimizing the signal processing in the feedback loop and\nprovide a theoretical model explaining the optimization result."
    },
    {
        "anchor": "Electronic and transport properties in geometrically disordered graphene\n  antidot lattices: A graphene antidot lattice, created by a regular perforation of a graphene\nsheet, can exhibit a considerable band gap required by many electronics\ndevices. However, deviations from perfect periodicity are always present in\nreal experimental setups and can destroy the band gap. Our numerical\nsimulations, using an efficient linear-scaling quantum transport simulation\nmethod implemented on graphics processing units, show that disorder that\ndestroys the band gap can give rise to a transport gap caused by Anderson\nlocalization. The size of the defect induced transport gap is found to be\nproportional to the radius of the antidots and inversely proportional to the\nsquare of the lattice periodicity. Furthermore, randomness in the positions of\nthe antidots is found to be more detrimental than randomness in the antidot\nradius. The charge carrier mobilities are found to be very small compared to\nvalues found in pristine graphene, in accordance with recent experiments.",
        "positive": "Spin relaxation in corrugated graphene: In graphene, out-of-plane (flexural) vibrations and static ripples imposed by\nthe substrate relax the electron spin, intrinsically protected by mirror\nsymmetry. We calculate the relaxation times in different scenarios, accounting\nfor all the possible spin-phonon couplings allowed by the hexagonal symmetry of\nthe lattice. Scattering by flexural phonons imposes the ultimate bound to the\nspin lifetimes, in the ballpark of hundreds of nano-seconds at room\ntemperature. This estimate and the behavior as a function of the carrier\nconcentration are substantially altered by the presence of tensions or the\npinning with the substrate. Static ripples also influence the spin transport in\nthe diffusive regime, dominated by motional narrowing. We find that the\nD'yakonov-Perel' mechanism saturates when the mean free path is comparable to\nthe correlation length of the heights profile. In this regime, the\nspin-relaxation times are exclusively determined by the geometry of the\ncorrugations. Simple models for typical corrugations lead to lifetimes of the\norder of tens of micro-seconds."
    },
    {
        "anchor": "Large interfacial spin-orbit torques in layered antiferromagnetic\n  insulator NiPS$_3$/ferromagnet bilayers: Finding efficient ways of manipulating magnetic bits is one of the core goals\nin spintronic research. Electrically-generated spin-orbit torques (SOTs) are\ngood candidates for this and the search for materials capable of generating\nhighly-efficient SOTs has gained a lot of traction in the recent years. While\nantiferromagnet/ferromagnet bilayer structures have been employed extensively\nfor passive applications, e.g. by using exchange bias fields, their active\nproperties are not yet widely employed. Here we show the presence of large\ninterfacial SOTs in bilayer of a ferromagnet and the two-dimensional layered\nantiferromagnetic insulator NiPS$_3$. We observe a large in-plane damping-like\ninterfacial torque, showing a torque conductivity of $\\sigma_\\mathrm{DL}\n\\approx 1 \\times 10^{5} \\mathrm{(\\frac{\\hbar}{2e}) /(\\Omega m)}$ even at room\ntemperature, comparable to the best devices reported in the literature for\nstandard heavy-metal-based and topological insulators-based devices.\nAdditionally, our devices also show an out-of-plane field-like torque arising\nfrom the NiPS$_3$/ferromagnet interface, further indicating the presence of an\ninterfacial spin-orbit coupling in our structures. Temperature-dependent\nmeasurements reveal an increase of the SOTs with a decreasing temperature below\nthe N\\'eel temperature of NiPS$_3$ ($T_N \\approx 170 \\mathrm{K}$), pointing to\na possible effect of the magnetic ordering on our measured SOTs. Our findings\nshow the potential of antiferromagnetic insulators and two-dimensional\nmaterials for future spintronic applications.",
        "positive": "Conductance peaks in open quantum dots: We present a simple measure of the conductance fluctuations in open ballistic\nchaotic quantum dots, extending the number of maxima method originally proposed\nfor the statistical analysis of compound nuclear reactions. The average number\nof extreme points (maxima and minima) in the dimensionless conductance, $T$, as\na function of an arbitrary external parameter $Z$, is directly related to the\nautocorrelation function of $T(Z)$. The parameter $Z$ can be associated to an\napplied gate voltage causing shape deformation in quantum dot, an external\nmagnetic field, the Fermi energy, etc.. The average density of maxima is found\nto be $<\\rho_{Z}> = \\alpha_{Z}/Z_c$, where $\\alpha_{Z}$ is a universal constant\nand $Z_c$ is the conductance autocorrelation length, which is system specific.\nThe analysis of $<\\rho_{Z}>$ does not require large statistic samples,\nproviding a quite amenable way to access information about parametric\ncorrelations, such as $Z_c$."
    },
    {
        "anchor": "The Birth of a Plasmonic Topological Quasiparticle on the Nanofemto\n  Scale: At interface of the classical and quantum physics Maxwell and Schr\\\"odinger\nequations describe how optical fields drive and control electronic phenomena at\nTHz or PHz frequencies and on ultra-small scales to enable lightwave\nelectronics. Light striking a metal surface triggers electric field-electron\nparticle/wave interactions to coherently imprint and transfer its attributes on\nthe attosecond time scale. Here we create and image by ultrafast photoemission\nelectron microscopy a new quasiparticle of optical field-collective electron\ninteraction where the design of geometrical phase creates a plasmonic\ntopological spin angular momentum texture. The spin texture resembles that of\nmagnetic meron quasiparticle, is localized within 1/2 wavelength of light, and\nexists on ~20 fs (2^10-14 s) time scale of the plasmonic field. The\nquasiparticle is created in a nanostructured silver film, which converts\ncoherent linearly polarized light pulse into an evanescent surface plasmon\npolariton light-electron wave with a tailored geometric phase to form a\nplasmonic vortex. Ultrafast coherent microscopy imaging of electromagnetic\nwaves propagating at the local speed of light of 255 nm/fs, electromagnetic\nsimulations, and analytic theory find a new quasiparticle within the vortex\ncore, with topological spin properties of a meron that are defined by the\noptical field and sample geometry. The new quasiparticle is an ultrafast\ntopological defect whose chiral field breaks the time-inversion symmetry on the\nnanoscale; its creation, symmetry breaking topology, and dynamics pertain to\ncontexts ranging from the cosmological structure creation to topological phase\ntransitions in quantum liquids and gases, and may act as a transducer for\nquantum information on the nanofemto scale.",
        "positive": "Band gap formation in commensurate twisted bilayer graphene/hBN moir\u00e9\n  lattices: We report on the investigation of periodic superstructures in twisted bilayer\ngraphene (tBLG) van-der-Waals heterostructures, where one of the graphene\nlayers is aligned to hexagonal boron nitride (hBN). Our theoretical simulations\nreveal that if the ratio of the resulting two moir\\'e unit cell areas is a\nsimple fraction, the graphene/hBN moir\\'e lattice acts as a staggered\npotential, breaking the degeneracy between tBLG AA sites. This leads to\nadditional band gaps at energies where a subset of tBLG AA sites is fully\noccupied. These gaps manifest as Landau fans in magnetotransport, which we\nexperimentally observe in an aligned tBLG/hBN heterostructure. Our study\ndemonstrates the identification of commensurate tBLG/hBN van-der-Waals\nheterostructures by magnetotransport, highlights the persistence of moir\\'e\neffects on length scales of tens of nanometers, and represents an interesting\nstep forward in the ongoing effort to realise designed quantum materials with\ntailored properties."
    },
    {
        "anchor": "Ferromagnetic order induced on graphene by Ni/Co proximity effects: We build a tight-binding Hamiltonian describing Co/Ni over graphene,\ncontemplating ATOP (a Co/Ni atom on top of each Carbon atom of one graphene\nsublattice) and HCP (one Co/Ni atom per Graphene plaquette) configurations. For\nthe ATOP configuration the orbitals involved, for the Co/Ni, are the\n$d_{z^2-r^2}$ which most strongly couple to one graphene sublattice and the\n$d_{xz}$, $d_{yz}$ orbitals that couple directly to the second sublattice site.\nSuch configuration is diagonal in pseudo-spin and spin space, yielding electron\ndoping of the graphene and antiferro-magnetic ordering in the primitive cell in\nagreement with DFT calculations. The second, HCP configuration is symmetric in\nthe graphene sublattices and only involves coupling to the $d_{xz}$, $d_{yz}$\norbitals. The register of the lattices in this case allows for a new coupling\nbetween nearest neighbour sites, generating non-diagonal terms in the\npseudo-spin space and novel spin-kinetic couplings mimicking a spin-orbit\ncoupling generated by a magnetic coupling. The resulting proximity effect in\nthis case yields ferromagnetic order in the graphene substrate. We derive the\nband structure in the vicinity of the K points for both configurations, the\nBloch wavefunctions and their spin polarization.",
        "positive": "Magnetically-induced reconstructions of the ground state in a\n  few-electron Si quantum dot: We report unexpected fluctuations in the positions of Coulomb blockade peaks\nat high magnetic fields in a small Si quantum dot. The fluctuations have a\ndistinctive saw-tooth pattern: as a function of magnetic field, linear shifts\nof peak positions are compensated by abrupt jumps in the opposite direction.\nThe linear shifts have large slopes, suggesting formation of the ground state\nwith a non-zero angular momentum. The value of the momentum is found to be well\ndefined, despite the absence of the rotational symmetry in the dot."
    },
    {
        "anchor": "Novel valley depolarization dynamics and valley Hall effect of exciton\n  in mono- and bilayer MoS$_2$: We investigate the valley depolarization dynamics and valley Hall effect of\nexciton due to the electron-hole exchange interaction in mono- and bilayer\nMoS$_2$ by solving the kinetic spin Bloch equations. The effect of the exciton\nenergy spectra by the electron-hole exchange interaction is explicitly\nconsidered. For the valley depolarization dynamics, in the monolayer MoS$_2$,\nit is found that in the strong scattering regime, the conventional motional\nnarrowing picture is no longer valid, and a novel valley depolarization channel\nis opened. For the valley Hall effect of exciton, in both the mono- and bilayer\nMoS$_2$, with the exciton equally pumped in the K and K' valleys, the system\ncan evolve into the equilibrium state where the valley polarization is parallel\nto the effective magnetic field due to the exchange interaction. With the drift\nof this equilibrium state by applied uniaxial strain, the exchange interaction\ncan induce the {\\it momentum-dependent} valley/photoluminesence polarization,\nwhich leads to the valley/photoluminesence Hall current. Specifically, the\ndisorder strength dependence of the valley Hall conductivity is revealed. In\nthe strong scattering regime, the valley Hall conductivity decreases with the\nincrease of the disorder strength; whereas in the weak scattering regime, it\nsaturates to a constant, which can be much larger than the one in Fermi system\ndue to the absence of the Pauli blocking.",
        "positive": "Phase separation in the two-dimensional electron liquid in MOSFETs: We show that the existence of an intermediate phase between the Fermi liquid\nand the Wigner crystal phases is a generic property of the two-dimensional pure\nelectron liqd in MOSFET's at zero temperature. The physical reason for the\nexistence of these phases is a partial separation of the uniform phases.\n  We discuss properties of these phases and a possible explanation of\nexperimental results on transport properties of low density electron gas in Si\nMOSFET's. We also argue that in certain range of parameters the partial phase\nseparation corresponds to a supersolid phas e discussed in [AndreevLifshitz]."
    },
    {
        "anchor": "Effects of Transverse Magnetic Anisotropy on Current-Induced Spin\n  Switching: Spin-polarized transport through bistable magnetic adatoms or single-molecule\nmagnets (SMMs), which exhibit both uniaxial and transverse magnetic anisotropy,\nis considered theoretically. The main focus is on the impact of transverse\nanisotropy on transport characteristics and the adatom's/SMM's spin. In\nparticular, we analyze the role of quantum tunneling of magnetization (QTM) in\nthe mechanism of the current-induced spin switching, and show that the QTM\nphenomenon becomes revealed as resonant peaks in the average values of the\nmolecule's spin and in the charge current. These features appear at some\nresonant fields and are observable when at least one of the electrodes is\nferromagnetic. We also show that the conductance generally depends on the\nrelative orientation of the average adatom's/SMM's spin and electrode's\nmagnetic moment. This spin-valve like magnetoresistance effect can be used to\ncontrol spin switching of the adatom's/SMM's spin.",
        "positive": "Spinor superfluid currents of exciton-polaritons on a split-ring: Recently, split-ring bosonic condensates of exciton polaritons have been\nproposed for realisation of qubits. We formulate an analytical model of a\npolariton condensate in a one-dimensional ring split by a delta-function\npotential. The persistent current is stopped by the potential defect embedded\nin a scalar condensate of non-interacting particles, however, it reappears in\nthe presence of an up-critical non-linearity. The nonlinear supercurrents are\ncharacterised by fractional orbital momenta while their eigenfunctions may\nfeature grey or dark solitons. The coupling between the spin and the orbital\nangular momentum of a spinor condensate affects persistent currents crucially.\nWe show that the spin-orbit interaction (SOI) induces the net superfluid\ncurrent in the condensate with a spatially uniform spin polarisation. We also\nfind solutions where the SOI-induced currents of two spin components of the\ncondensate propagate in opposite directions. The corresponding states of spinor\ncondensates obey a combined mirror reflection and the spin-flip symmetry."
    },
    {
        "anchor": "Fluctuational internal Josephson effect in topological insulator film: Tunneling between opposite surfaces of topological insulator thin film\npopulated by electrons and holes is considered. We predict considerable\nenhancement of tunneling conductivity by Cooper electron-hole pair fluctuations\nthat are precursor of their Cooper pairing. Cooper pair fluctuations lead to\nthe critical behavior of tunneling conductivity in vicinity of critical\ntemperature with critical index \\nu=2. If the pairing is suppressed by disorder\nthe behavior of tunneling conductivity in vicinity of quantum phase transition\nis also critical with the index \\mu=2. The effect can be interpreted as\nfluctuational internal Josephson effect and it is general phenomenon for\nelectron-hole bilayers. The peculiarities of the effect in other realizations\nof electron-hole bilayer are discussed.",
        "positive": "Superstatistics - a quantum generalization: A quantum mechanical generalization of superstatistics is presented here\nbased on the positive operator valued measure transformation property of the\nsystem density matrix. This procedure reveals that the origin of the\nfluctuating factors occurring in the derivation of the superstatistics lies in\nthe choice of the transformation operators governing the dynamics of\nfluctuations. This generalization addresses situations such as nanosystems\nbased on quantum devices (e.g., superconducting devices, single electron\ntransistors, etc,) operating at low temperatures where cognizance of quantum\nfluctuations is essential."
    },
    {
        "anchor": "Electronic and structural properties of rhombohedral [111] and [110]\n  oriented ultra-thin bismuth nanowires: Structures and electronic properties of rhombohedral [111] and [110] bismuth\nnanowires are calculated with the use of density functional theory. The\nformation of an energy band gap from quantum confinement is studied and to\nimprove estimates for the band gap the GW approximation is applied. The [111]\noriented nanowires require surface bonds to be chemically saturated to avoid\nformation of metallic surface states whereas the surface of the [110] nanowires\ndo not support metallic surface states. It is found that the onset of quantum\nconfinement in the surface passivated [111] nanowires occurs at larger critical\ndimensions than for the [110] nanowires. For the [111] oriented nanowires it is\npredicted that a band gap of approximately 0.5 eV can be formed at a diameter\nof approximately 6 nm, whereas for the [110] oriented nanowires a diameter of\napproximately 3 nm is required to achieve a similar band gap energy. The GW\ncorrection is also applied to estimates of the electron affinity, ionisation\npotentials and work functions for both orientations of the nanowires for\nvarious diameters below 5 nm. The magnitude of the energy band gaps that arise\nin bismuth at critical dimensions of a few nanometers are of the same order as\nfor conventional bulk semiconductors.",
        "positive": "Toggle-switch-like crossover between two types of isolated skyrmions\n  within the conical phase of cubic helimagnets: We investigate the field-induced crossover between two types of isolated\nskyrmions that exist within the conical phase of cubic helimagnets and orient\nthemselves either along or perpendicular to the field. Such a crossover takes\nplace for the same value of the field, at which the closely packed skyrmion\nlattice was predicted to stabilize in the A-phase region. The clusters and a\nskyrmion lattice comprised by the skyrmions perpendicular to the field,\nhowever, are unfavorable and lose their stability as compared with the\nskyrmions parallel to the field. We also followed transformation of\nperpendicular skyrmions into pairs of merons that rupture the helical state. An\nattractive interactions between different types of isolated skyrmions make it\nfeasible to construct complex cluster states with the cubic arrangement of\nskyrmions."
    },
    {
        "anchor": "Scalable Sources of Entangled Photons with Wavelength on Demand: The prospect of using the quantum nature of light for secure communication\nkeeps spurring the search and investigation of suitable sources of\nentangled-photons. Semiconductor quantum dots are arguably the most attractive.\nThey can generate indistinguishable entangled-photons deterministically, and\nare compatible with current photonic-integration technologies, a set of\nproperties not shared by any other entanglement resource. However, as no two\nquantum dots are identical, they emit entangled-photons with random energies.\nThis hinders their exploitation in communication protocols requiring\nentangled-states with well-defined energies. Here, we introduce scalable\nquantum-dot-based sources of polarization-entangled-photons whose energy can be\ncontrolled via dynamic strain-engineering without degrading the degree of\nentanglement of the source. As a test-bench, we interface quantum dots with\nclouds of atomic vapours, and we demonstrate slow-entangled-photons from a\nsingle quantum emitter. These results pave the way towards the implementation\nof hybrid quantum networks where entanglement is distributed among distant\nparties using scalable optoelectronic devices.",
        "positive": "Chiral Flat Bands: Existence, Engineering and Stability: We study flat bands in bipartite tight-binding networks with discrete\ntranslational invariance. Chiral flat bands with chiral symmetry eigenenergy E\n= 0 and host compact localized eigenstates for finite range hopping. For a\nbipartite network with a majority sublattice chiral flat bands emerge. We\npresent a simple generating principle of chiral flat band networks and as a\nshowcase add to the previously observed cases a number of new potentially\nrealizable chiral flat bands in various lattice dimensions. Chiral symmetry\nrespecting network perturbations - including disorder and synthetic magnetic\nfields - preserve both the flatband and the modified compact localized states.\nChiral flatbands are spectrally protected by gaps, and pseudogaps in the\npresence of disorder due to Griffiths effects."
    },
    {
        "anchor": "Finite frequency quantum noise in an interacting mesoscopic conductor: We present a quantum calculation based on scattering theory of the frequency\ndependent noise of current in an interacting chaotic cavity. We include\ninteractions of the electron system via long range Coulomb forces between the\nconductor and a gate with capacitance $C$. We obtain explicit results\nexhibiting the two time scales of the problem, the cavity's dwell time $\\tau_D$\nand the $RC$-time $\\tau_C$ of the cavity {\\em vis \\`a vis} the gate. The noise\nshows peculiarities at frequencies of the order and exceeding the inverse\ncharge relaxation time $\\tau^{-1} = \\tau^{-1}_D+\\tau^{-1}_C $.",
        "positive": "Non-reciprocity of spin waves in magnetic nanotubes with helical\n  equilibrium magnetization: Spin waves (SWs) in magnetic nanotubes have shown interesting nonreciprocal\nproperties in their dispersion relation, group velocity, frequency linewidth\nand attenuation lengths. The reported chiral effects are similar to those\ninduced by the Dzyaloshinskii-Moriya interaction, but originating from the\ndipole-dipole interaction. Here we show, that the isotropic-exchange\ninteraction can also induce chiral effects in the SW transport; the so-called\nBerry phase of SWs. We demonstrate that with the application of magnetic\nfields, the nonreciprocity of the different SW modes can be tuned between the\nfully dipolar governed and the fully exchange governed cases, as they are\ndirectly related to the underlaying equilibrium state. In the helical state,\ndue to the combined action of the two effects every single sign combination of\nthe azimuthal and axial wave vectors leads to different dispersion, allowing\nfor a very sophisticated tuning of the SW transport. A disentanglement of the\ndipole-dipole and exchange contributions so far was not reported for the SW\ntransport in nanotubes. Furthermore, we propose a device based on coplanar\nwaveguides that would allow to selectively measure the exchange or dipole\ninduced SW nonreciprocities. In the context of magnonic applications, our\nresults might encourage further developments in the emerging field of 3D\nmagnonic devices using curved magnetic membranes."
    },
    {
        "anchor": "Charge and spin transport in edge channels of a $\u03bd=0$ quantum Hall\n  system on the surface of topological insulators: Three-dimensional topological insulators of finite thickness can show the\nquantum Hall effect (QHE) at the filling factor $\\nu=0$ under an external\nmagnetic field if there is a finite potential difference between the top and\nbottom surfaces. We calculate energy spectra of surface Weyl fermions in the\n$\\nu=0$ QHE and find that gapped edge states with helical spin structure are\nformed from Weyl fermions on the side surfaces under certain conditions. These\nedge channels account for the nonlocal charge transport in the $\\nu=0$ QHE\nwhich is observed in a recent experiment on (Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ films.\nThe edge channels also support spin transport due to the spin-momentum locking.\nWe propose an experimental setup to observe various spintronics functions such\nas spin transport and spin conversion.",
        "positive": "Skyrmions in integral and fractional quantum Hall systems: Numerical results are presented for the spin excitations of a two-dimensional\nelectron gas confined to a quantum well of width w. Spin waves and charged\nskyrmion excitations are studied for filling factors nu=1, 3, and 1/3. Phase\ndiagrams for the occurrence of skyrmions of different size as a function of w\nand the Zeeman energy are calculated. For nu=3, skyrmions occur only if w is\nlarger than about twice the magnetic length. A general necessary condition on\nthe interaction pseudopotential for the occurrence of stable skyrmion states is\nproposed."
    },
    {
        "anchor": "Computational search for ultrasmall and fast skyrmions in the Inverse\n  Heusler family: Skyrmions are magnetic excitations that are potentially ultrasmall and\ntopologically protected, making them interesting for high-density\nall-electronic ultrafast storage applications. While recent experiments have\nconfirmed the existence of various types of skyrmions, their typical sizes are\nmuch larger than traditional domain walls, except at very low temperature. In\nthis work, we explore the optimal material parameters for hosting ultra-small,\nfast, and room temperature stable skyrmions. As concrete examples, we explore\npotential candidates from the inverse Heusler family. Using first-principles\ncalculations of structural and magnetic properties, we identify several\npromising ferrimagnetic inverse Heusler half-metal/near half-metals and analyze\ntheir phase space for size and metastability.",
        "positive": "Exciton landscape in van der Waals heterostructures: van der Waals heterostructures consisting of vertically stacked\ntransition-metal dichalcogenides (TMDs) exhibit a rich landscape of bright and\ndark intra- and interlayer excitons. In spite of a growing literature in this\nfield of research, the type of excitons dominating optical spectra in different\nvan der Waals heterostructures has not yet been well established. The spectral\nposition of exciton states depends strongly on the strength of hybridization\nand energy renormalization due to the periodic moir\\'e potential. Combining\nexciton density-matrix formalism and density-functional theory, we shed light\non the exciton landscape in TMD homo- and heterobilayers at different\nstackings. This allows us to identify on a microscopic footing the\nenergetically lowest-lying exciton state for each material and stacking.\nFurthermore, we disentangle the contribution of hybridization and layer\npolarization-induced alignment shifts of dark and bright excitons in\nphotoluminescence spectra. By revealing the exciton landscape in van der Waals\nheterostructures, our work provides the basis for further studies of the\noptical, dynamical, and transport properties of this technologically promising\nclass of nanomaterials."
    },
    {
        "anchor": "Electronic and optical properties of electromigrated molecular junctions: Electromigrated nanoscale junctions have proven very useful for studying\nelectronic transport at the single-molecule scale. However, confirming that\nconduction is through precisely the molecule of interest and not some\ncontaminant or metal nanoparticle has remained a persistent challenge,\ntypically requiring a statistical analysis of many devices. We review how\ntransport mechanisms in both purely electronic and optical measurements can be\nused to infer information about the nanoscale junction configuration. The\nelectronic response to optical excitation is particularly revealing. We briefly\ndiscuss surface-enhanced Raman spectroscopy on such junctions, and present new\nresults showing that currents due to optical rectification can provide a means\nof estimating the local electric field at the junction due to illumination.",
        "positive": "Exciton spin dynamics of colloidal CdTe nanocrystals in magnetic field: The recombination and spin dynamics of excitons in colloidal CdTe\nnanocrystals (NCs) are studied by time-resolved photoluminescence in high\nmagnetic fields up to 15 T and at cryogenic temperatures. The recombination\ndecay shows a nonexponential temporal behavior, with the longest component\ncorresponding to the dark excitons having 260 ns decay time at zero magnetic\nfield and 4.2 K temperature. This long component shortens to 150 ns at 15 T due\nto the magnetic-field-induced mixing of the bright and dark exciton states. The\nspin dynamics, assessed through the evolution of the magnetic-field-induced\ncircular polarization degree of the photoluminescence, has a fast component\nshorter than 1 ns related to the bright excitons and a slow component of 5-10\nns associated with the dark excitons. The latter shortens with increasing\nmagnetic field, which is characteristic for a phonon-assisted spin relaxation\nmechanism. The relatively low saturation level of the associated\nmagnetic-field-induced circular polarization degree of -30 % is explained by a\nmodel that suggests the CdTe NCs to constitute an ensemble of prolate and\noblate NCs, both having a structural quantization axis. The exciton g-factor of\n2.4-2.9 evaluated from fitting the experimental data in the frame of the\nsuggested approach is in good agreement with the expected value for the dark\nexcitons in CdTe NCs."
    },
    {
        "anchor": "Equilibration of Luttinger liquid and conductance of quantum wires: Luttinger liquid theory describes one-dimensional electron systems in terms\nof non-interacting bosonic excitations. In this approximation thermal\nexcitations are decoupled from the current flowing through a quantum wire, and\nthe conductance is quantized. We show that relaxation processes not captured by\nthe Luttinger liquid theory lead to equilibration of the excitations with the\ncurrent and give rise to a temperature-dependent correction to the conductance.\nIn long wires, the magnitude of the correction is expressed in terms of the\nvelocities of bosonic excitations. In shorter wires it is controlled by the\nrelaxation rate.",
        "positive": "Probing interactions in mesoscopic gold wires: We have measured in gold wires the energy exchange rate between\nquasiparticles, the phase coherence time of quasiparticles and the resistance\nvs. temperature, in order to probe the interaction processes which are relevant\nat low temperatures. We find that the energy exchange rate is higher than\nexpected from the theory of electron-electron interactions, and that it has a\ndifferent energy dependence. The dephasing time is constant at temperatures\nbetween 8 K and 0.5 K, and it increases below 0.5 K. The magnetoresistance is\nnegative at large field scales, and the resistance decreases logarithmically\nwith increasing temperatures, indicating the presence of magnetic impurities,\nprobably Fe. Whereas resistivity and phase coherence measurements can be\nattributed to magnetic impurities, the question is raised whether these\nmagnetic impurities could also mediate energy exchanges between quasiparticles."
    },
    {
        "anchor": "Sub 200fs pulse generation from a graphene mode-locked fiber laser: Ultrafast fiber lasers with short pulses and broad bandwidth are in great\ndemand for a variety of applications, such as spectroscopy, biomedical\ndiagnosis and optical communications. In particular sub-200fs pulses are\nrequired for ultrafast spectroscopy with high temporal resolution. Graphene is\nan ideal ultra-wide-band saturable absorber. We report the generation of 174fs\npulses from a graphene-based fiber laser",
        "positive": "Deterministic generation of all-photonic quantum repeaters from\n  solid-state emitters: Quantum repeaters are nodes in a quantum communication network that allow\nreliable transmission of entanglement over large distances. It was recently\nshown that highly entangled photons in so-called graph states can be used for\nall-photonic quantum repeaters, which require substantially fewer resources\ncompared to atomic-memory based repeaters. However, standard approaches to\nbuilding multi-photon entangled states through pairwise probabilistic\nentanglement generation severely limit the size of the state that can be\ncreated. Here, we present a protocol for the deterministic generation of large\nphotonic repeater states using quantum emitters such as semiconductor quantum\ndots and defect centers in solids. We show that arbitrarily large repeater\nstates can be generated using only two coupled emitters, reducing the necessary\nnumber of photon sources by six orders of magnitude. Our protocol includes a\nbuilt-in redundancy which makes it resilient to photon loss."
    },
    {
        "anchor": "Equilibrium and non-equilibrium electron tunneling via discrete quantum\n  states: Tunneling is measured via the quantum levels of a metal nanoparticle. We\nanalyze quantitatively the resonance energies, widths, and amplitudes, both in\nthe regime where only one state is accessible for tunneling and in the\nnon-equilibrium regime when additional states are made accessible one-by-one.\nFor tunneling through one state, our results agree with expectations for\nsequential tunneling, but in the non-equilibrium regime the resonances are\nbroadened and shifted in ways that require taking into account electron\ninteractions and relaxation.",
        "positive": "Development and operation of the twin radio frequency single electron\n  transistor for solid state qubit readout: Ultra-sensitive detectors and readout devices based on the radio frequency\nsingle electron transistor (rf-SET) combine near quantum-limited sensitivity\nwith fast operation. Here we describe a twin rf-SET detector that uses two\nsuperconducting rf-SETs to perform fast, real-time cross-correlated\nmeasurements in order to distinguish sub-electron signals from charge noise on\nmicrosecond time-scales. The twin rf-SET makes use of two tuned resonance\ncircuits to simultaneously and independently address both rf-SETs using\nwavelength division multiplexing (WDM) and a single cryogenic amplifier. We\nfocus on the operation of the twin rf-SET as a charge detector and evaluate the\ncross-talk between the two resonance circuits. Real time suppression of charge\nnoise is demonstrated by cross correlating the signals from the two rf-SETs.\nFor the case of simultaneous operation, the rf-SETs had charge sensitivities of\n$\\delta q_{SET1} = 7.5 \\mu e/\\sqrt{Hz}$ and $\\delta q_{SET2} = 4.4 \\mu\ne/\\sqrt{Hz}$."
    },
    {
        "anchor": "Fast generation of entangled photon pairs from a single quantum dot\n  embedded in a photonic crystal cavity: We present a scheme for the fast generation of entangled photons from a\nsingle quantum dot coupled to a planar photonic crystal that support two\northogonally polarized cavity modes. We discuss ``within generation'' and\n``across generation'' of entangled photons when both biexciton to exciton, and\nexciton to ground state transitions, are coupled through cavity modes. In the\nacross generation, the photon entanglement is restored through a time delay\nbetween the photons. The two photon concurrence, which is a measure of\nentanglement, is greater than 0.7 and 0.8 using experimentally achievable\nparameters in across generation and within generation, respectively. We also\nshow that the entanglement can be distilled in both cases using a simple\nspectral filter.",
        "positive": "Magnetic effects on nonlinear mechanical properties of a suspended\n  carbon nanotube: We propose a microscopic model for a nanoelectromechanical system made by a\nradio-frequency driven suspended carbon nanotube (CNT) in the presence of an\nexternal magnetic field perpendicular to the current. As a main result, we show\nthat, when the device is driven far from equilibrium, one can tune the CNT\nmechanical properties by varying the external magnetic field. Indeed, the\nmagnetic field affects the CNT bending mode dynamics inducing an enhanced\ndamping as well as a noise term due to the electronic phase fluctuations. The\nquality factor, as observed experimentally, exhibits a quadratic dependence on\nexternal magnetic field strength. Finally, CNT resonance frequencies as a\nfunction of gate voltage acquire, increasing the magnetic field strength, a\npeculiar dip-peak structure that should be experimentally observed."
    },
    {
        "anchor": "Resonance Beyond Frequency-Matching: Resonance, defined as the oscillation of a system when the temporal frequency\nof an external stimulus matches a natural frequency of the system, is important\nin both fundamental physics and applied disciplines. However, the spatial\ncharacter of oscillation is not considered in the definition of resonance. In\nthis work, we reveal the creation of spatial resonance when the stimulus\nmatches the space pattern of a normal mode in an oscillating system. The\ncomplete resonance, which we call multidimensional resonance, is a combination\nof both the spatial and the conventionally defined (temporal) resonance and can\nbe several orders of magnitude stronger than the temporal resonance alone. We\nfurther elucidate that the spin wave produced by multidimensional resonance\ndrives considerably faster reversal of the vortex core in a magnetic nanodisk.\nOur findings provide insight into the nature of wave dynamics and open the door\nto novel applications.",
        "positive": "Intrinsic Spin Torque Without Spin-Orbit Coupling: We derive an intrinsic contribution to the non-adiabatic spin torque for\nnon-uniform magnetic textures. It differs from previously considered\ncontributions in several ways and can be the dominant contribution in some\nmodels. It does not depend on the change in occupation of the electron states\ndue to the current flow but rather is due to the perturbation of the electronic\nstates when an electric field is applied. Therefore it should be viewed as\nelectric-field-induced rather than current-induced. Unlike previously reported\nnon-adiabatic spin torques, it does not originate from extrinsic relaxation\nmechanisms nor spin-orbit coupling. This intrinsic non-adiabatic spin torque is\nrelated by a chiral connection to the intrinsic spin-orbit torque that has been\ncalculated from the Berry phase for Rashba systems."
    },
    {
        "anchor": "Transmission zero in a quantum dot with strong electron-electron\n  interaction: Perturbative conductance calculations: A pioneering experiment [E. Schuster, E. Buks, M. Heiblum, D. Mahalu, V.\nUmansky, and Hadas Shtrikman, Nature 385, 417 (1997)] reported the measurement\nof the transmission phase of an electron traversing a quantum dot and found the\nintriguing feature of a sudden phase drop in the conductance valleys. Based on\nthe Friedel sum rule for a spinless effective one-dimensional system, it has\nbeen previously argued [H.-W. Lee, Phys. Rev. Lett. 82, 2358 (1999)] that the\nsudden phase drop should be accompanied by the vanishing of the transmission\namplitude, or transmission zero. Here we address roles of strong\nelectron-electron interactions on the electron transport through a two-level\nquantum dot where one level couples with the leads much more strongly than the\nother level does [P. G. Silvestrov and Y. Imry, Phys. Rev. Lett. 85, 2565\n(2000)]. We perform a perturbative conductance calculation with an explicit\naccount of large charging energy and verify that the resulting conductance\nexhibits transmission zero, in agreement with the analysis based on the Friedel\nsum rule.",
        "positive": "A new signature for strong light-matter coupling using spectroscopic\n  ellipsometry: Light-matter interactions can occur when an ensemble of molecular resonators\nis placed in a confined electromagnetic field. In the strong coupling regime\nthe rapid exchange of energy between the molecules and the electromagnetic\nfield results in the emergence of hybrid light-matter states called polaritons.\nMultiple criteria exist to define the strong coupling regime, usually by\ncomparing the splitting of the polariton bands with the linewidths of the\nuncoupled modes. Here we highlight the limitations of these criteria and study\nstrong coupling using spectroscopic ellipsometry, a commonly used optical\ncharacterisation technique. We identify a new signature of strong coupling in\nellipsometric phase spectra. Combining ellipsometric amplitude and phase\nspectra yields a distinct topological feature that we suggest could serve as a\nnew criterion for strong coupling. Our results introduce the idea of\nellipsometric topology and could provide further insight into the transition\nfrom the weak to strong coupling regime."
    },
    {
        "anchor": "A Graphene-based Hot Electron Transistor: We experimentally demonstrate DC functionality of graphene-based hot electron\ntransistors, which we call Graphene Base Transistors (GBT). The fabrication\nscheme is potentially compatible with silicon technology and can be carried out\nat the wafer scale with standard silicon technology. The state of the GBTs can\nbe switched by a potential applied to the transistor base, which is made of\ngraphene. Transfer characteristics of the GBTs show ON/OFF current ratios\nexceeding 50.000.",
        "positive": "Quantum Phase Transitions and Particle-Hole Pair Transport in\n  Capacitively Coupled Josephson-Junction Chains: We consider two chains of ultrasmall Josephson junctions, coupled\ncapacitively with each other, and investigate the transport of particle-hole\npairs and the quantum phase transitions at zero temperature. For appropriate\nparameter ranges, the particle-hole pairs are found to play major roles in\ntransport phenomena; condensation of such pairs leads to the superconducting\nstate, displaying perfect drag of supercurrents along the two chains."
    },
    {
        "anchor": "Chiral Partition Functions of Quantum Hall Droplets: Chiral partition functions of conformal field theory describe the edge\nexcitations of isolated Hall droplets. They are characterized by an index\nspecifying the quasiparticle sector and transform among themselves by a\nfinite-dimensional representation of the modular group. The partition functions\nare derived and used to describe electron transitions leading to Coulomb\nblockade conductance peaks. We find the peak patterns for Abelian hierarchical\nstates and non-Abelian Read-Rezayi states, and compare them. Experimental\nobservation of these features can check the qualitative properties of the\nconformal field theory description, such as the decomposition of the Hilbert\nspace into sectors, involving charged and neutral parts, and the fusion rules.",
        "positive": "Tuning Fano-type resonances in coupled quantum point contacts by\n  applying asymmetric voltages: We study the ballistic magnetotransport in a double quantum point contact\n(QPC) device consisting of a quasi-one-dimensional quantum wire with an\nembedded island-like impurity - etched nano-hole as in a recently published\nexperiment [J. C. Chen, Y. Lin, K.-T. Lin, T. Ueda and S. Komiyama, Appl. Phys.\nLett. 94, 012105 (2009)]. We reproduce the zero field quantized conductance,\nthe interference phenomenon induced by the coupled QPCs, as well as the\nRamsauer-like resonances observed in the experiments. At finite magnetic fields\nFano-type resonances arises in the conductance due to the formation of\nlocalized states at the impurity periphery and to an inter-edge state resonant\ncoupling effect. It is predicted that the Fano-type resonances can be\ncontrolled by an asymmetric confinement of the QPCs."
    },
    {
        "anchor": "Electronic Transport in Disordered Bilayer and Trilayer Graphene: We present a detailed numerical study of the electronic transport properties\nof bilayer and trilayer graphene within a framework of single-electron\ntight-binding model. Various types of disorder are considered, such as resonant\n(hydrogen) impurities, vacancies, short- or long-range Gaussian random\npotentials, and Gaussian random nearest neighbor hopping. The algorithms are\nbased on the numerical solution of the time-dependent Schr \\\"{o}dinger equation\nand applied to calculate the density of states and conductivities (via the Kubo\nformula) of large samples containing millions of atoms. In the cases under\nconsideration, far enough from the neutrality point, depending on the strength\nof disorders and the stacking sequence, a linear or sublinear electron-density\ndependent conductivity is found. The minimum conductivity $\\sigma_{\\min}\\approx\n2e^{2}/h$ (per layer) at the charge neutrality point is the same for bilayer\nand trilayer graphene, independent of the type of the impurities, but the\nplateau of minimum conductivity around the neutrality point is only observed in\nthe presence of resonant impurities or vacancies, originating from the\nformation of the impurity band.",
        "positive": "Novel primary photoexcitations in $\u03c0$-conjugated donor-acceptor\n  copolymers probed by transient magneto-photoinduced-absorption: The saga of the primary photoexcitations in $\\pi$-conjugated polymers has\nbeen a source of extraordinary scientific curiosity that has lasted for more\nthan three decades. From soliton excitations in trans-polyacetylene, to singlet\nand triplet excitons and polarons in other polymers, to charge transfer\nexcitons in blends of polymers and fullerenes, the field has been rich with a\nvariety of different photoexcitation species. Here we show the photogeneration\nof a novel primary intrachain photoexcitation species, namely the composite\nmulti-exciton (CME) in $\\pi$-conjugated donor-acceptor (DA)-copolymers used in\norganic photovoltaic (OPV) solar cells. We utilized the magnetic field response\nof the transient photoinduced absorption from sub-picosecond to millisecond to\nshow in pristine DA-copolymer early photogeneration of the CME species that is\ncomposed of four coupled spin 1/2 particles, having unique optical and magnetic\nsignatures. This species decomposes into two independent triplets in the\nmicrosecond time domain. Importantly in copolymer/fullerene blends the CME\nionization generates photocarriers by a unique process that may enhance the\nphotocurrent in OPV solar cells."
    },
    {
        "anchor": "Skyrmions in quantum Hall ferromagnets as spin-waves bound to unbalanced\n  magnetic flux quanta: A microscopic description of (baby)skyrmions in quantum Hall ferromagnets is\nderived from a scattering theory of collective (neutral) spin modes by a bare\nquasiparticle. We start by mapping the low lying spectrum of spin waves in the\nuniform ferromagnet onto that of free moving spin excitons, and then we study\ntheir scattering by the defect of charge. In the presence of this disturbance,\nthe local spin stiffness varies in space, and we translate it into an\ninhomogeneus metric in the Hilbert space supporting the excitons. An attractive\npotencial is then required to preserve the symmetry under global spin\nrotations, and it traps the excitons around the charged defect. The\nquasiparticle now carries a spin texture. Textures containing more than one\nexciton are described within a mean-field theory, the interaction among the\nexcitons being taken into account through a new renormalization of the metric.\nThe number of excitons actually bound depends on the Zeeman coupling, that\nplays the same role as a chemical potencial. For small Zeeman energies, the\ndefect binds many excitons which condensate. As the bound excitons have a unit\nof angular momentum, provided by the quantum of magnetic flux left unbalanced\nby the defect of charge, the resulting texture turns out to be a topological\nexcitation of charge 1. Its energy is that given by the non-linear sigma model\nfor the ground state in this topological sector, i.e. the texture is a\nskyrmion.",
        "positive": "Role of the proximity effect for normal-metal quasiparticle traps: The performance of many superconducting devices is degraded in presence of\nnon-equilibrium quasiparticles in the superconducting part. One promising\napproach towards their evacuation is the use of normal-metal quasiparticle\ntraps, where normal metal is brought into good metallic contact with the\nsuperconductor. A voltage biased normal-metal--insulator--superconductor\njunction equipped with such a trap is used to investigate on the trapping\nperformance and the part played by the superconducting proximity effect\ntherein. This involves an appropriate one-dimensional model of the junction and\nthe numerical solution of Usadel equations describing the non-equilibrium state\nof the superconductor. The functionality of the trap is determined by the\ndensity of states (DOS) at the tunnel barrier. Herein, the proximity effect\nleads to two antagonistic characteristics affecting the trapping performance:\nthe beneficial reduction of the DOS at an energy $|E| = \\Delta_{\\text{BCS}}$\nversus the contraction of the spectral energy gap causing quasiparticle\npoisoning. For both effects the trap position is decisive, which needs to be\ntaken into account for optimizing the trapping performance. In addition, the\nconversion between dissipative normal and supercurrent inside the\nsuperconducting part with its impact on the quasiparticle density is studied."
    },
    {
        "anchor": "Repulsive interactions of a lipid membrane with graphene in composite\n  materials: The van der Waals interaction between a lipid membrane and a substrate\ncovered by a graphene sheet is investigated using the Lifshitz theory. The\nreflection coefficients are obtained for a layered planar system submerged in\nwater. The dielectric response properties of the involved materials are also\nspecified and discussed. Our calculations show that a graphene covered\nsubstrate can repel the biological membrane in water. This is attributed to the\nsignificant changes in the response properties of the system due to the\nmonolayer graphene. It is also found that the van der Waals interaction is\nmostly dominated by the presence of graphene, while the role of the particular\nsubstrate is secondary.",
        "positive": "Phonons in a Nanoparticle Mechanically Coupled to a Substrate: The discrete nature of the vibrational modes of an isolated nanometer-scale\nsolid dramatically modifies its low-energy electron and phonon dynamics from\nthat of a bulk crystal. However, nanocrystals are usually coupled--even if only\nweakly--to an environment consisting of other nanocrystals, a support matrix,\nor a solid substrate, and this environmental interaction will modify the\nvibrational properties at low frequencies. In this paper we investigate the\nmodification of the vibrational modes of an insulating spherical nanoparticle\ncaused by a weak {\\it mechanical} coupling to a semi-infinite substrate. The\nphonons of the bulk substrate act as a bath of harmonic oscillators, and the\ncoupling to this reservoir shifts and broadens the nanoparticle's modes. The\nvibrational density of states in the nanoparticle is obtained by solving the\nDyson equation for the phonon propagator, and we show that environmental\ninteraction is especially important at low frequencies. As a probe of the\nmodified phonon spectrum, we consider nonradiative energy relaxation of a\nlocalized electronic impurity state in the nanoparticle, for which good\nagreement with experiment is found."
    },
    {
        "anchor": "Measurement of energy eigenstates by a slow detector: We propose a method for a weak continuous measurement of the energy\neigenstates of a fast quantum system by means of a \"slow\" detector. Such a\ndetector is only sensitive to slowly-changing variables, e. g. energy, while\nits back-action can be limited solely to decoherence of the eigenstate\nsuperpositions. We apply this scheme to the problem of detection of quantum\njumps between energy eigenstates in a harmonic oscillator.",
        "positive": "Tilted Dirac Fermions: We introduce the notion of a band-inverted, topological semimetal in\ntwo-dimensional nonsymmorphic crystals. This notion is materialized in the\nmonolayers of MTe$_2$ (M $=$ W, Mo) if spin-orbit coupling is neglected. We\ncharacterize the Dirac band touching topologically by the Wilson loop of the\nnon-Abelian Berry gauge field. An additional feature of the Dirac cone in\nmonolayer MTe$_2$ is that it tilts over in a Lifshitz transition to produce\nelectron and hole pockets, a type-II Dirac cone. These pockets, together with\nthe pseudospin structure of the Dirac electrons, suggest a unified, topological\nexplanation for the recently-reported, non-saturating magnetoresistance in\nWTe$_2$, as well as its circular dichroism in photoemission. We complement our\nanalysis and first-principle bandstructure calculations with an\n$\\textit{ab-initio}$-derived-derived tight-binding model for the WTe$_2$\nmonolayer."
    },
    {
        "anchor": "Cloaked Resonant States in Bilayer Graphene: Charge carriers in bilayer graphene occupy two parabolic continua of\nelectron-like and hole-like states which differ by the alignment between\ncarrier pseudospin and its momentum, the property known as chirality. Due to\nchirality conservation, a strong confining potential can host unusual bound\nstates: electron levels cloaked into the hole continuum. The energy levels and\nthe wave functions of the cloaked states can be obtained by solving the\nSchr\\\"odinger equation for a massive non-chiral particle in the p-wave channel\nin two dimensions. Eventually, cloaked states slowly decay into the continuum,\nvia trigonal warping effects. We discuss the key properties of cloaked states\nin circularly symmetric potentials, and show that cloaking should be observable\nin quantum corral geometries via scanning tunneling probe measurements.",
        "positive": "All-optical tailoring of single-photon spectra in a quantum-dot\n  microcavity system: Semiconductor quantum-dot cavity systems are promising sources for\nsolid-state based on-demand generation of single photons for quantum\ncommunication. Commonly, the spectral characteristics of the emitted single\nphoton are fixed by system properties such as electronic transition energies\nand spectral properties of the cavity. In the present work we study\nsingle-photon generation from the quantum-dot biexciton through a partly\nstimulated non-degenerate two-photon emission. We show that frequency and\nlinewidth of the single photon can be fully controlled by the stimulating laser\npulse, ultimately allowing for efficient all-optical spectral shaping of the\nsingle photon."
    },
    {
        "anchor": "Radio-frequency reflectometry on large gated 2-dimensional systems: We have embedded an AlGaAs/GaAs based, gated 2D hole system (2DHS) into an\nimpedance transformer $LC$ circuit, and show that by using radio-frequency\nreflectometry it is possible to perform sensitive, large bandwidth, electrical\nresistance measurements of 2D systems at mK temperatures. We construct a simple\nlumped element model where the gated 2DHS is described as a resistive\ntransmission line. The model gives a qualitative understanding of the\nexperimental results. As an example, we use our method to map out the Landau\nlevel evolution in a 2DHS as a function of magnetic field and gate voltage.",
        "positive": "Anomalous plasmon mode in strained Weyl semimetals: An exotic anomalous plasmon mode is found in strained Weyl semimetals\nutilizing the topological Landau Fermi liquid and chiral kinetic theories, in\nwhich quasiparticle interactions are modeled by long-range Coulomb and residual\nshort-range interactions. The gapped collective mode is derived from the\ndynamical charge pumping between the bulk and the surface and behaves like\n$k_{\\rm F}^{-1}$. The charge oscillations are accurately determined by the\ncoupling between the induced electric field and the background pseudofields.\nThis novel mode unidirectionally disperses along the pseudomagnetic field and\nmanifests itself in an unusual thermal conductivity in apparent violation of\nthe Wiedemann-Franz law. The excitation can be achieved experimentally by\nmechanical vibrations of the crystal lattice in the THz regime."
    },
    {
        "anchor": "Intrinsic and extrinsic spin-orbit coupling and spin relaxation in\n  monolayer PtSe$_2$: Monolayer PtSe$_2$ is a semiconducting transition metal dichalcogenide\ncharacterized by an indirect band gap, space inversion symmetry, and high\ncarrier mobility. Strong intrinsic spin-orbit coupling and the possibility to\ninduce extrinsic spin-orbit fields by gating make PtSe$_2$ attractive for\nfundamental spin transport studies as well as for potential spintronics\napplications. We perform a systematic theoretical study of the spin-orbit\ncoupling and spin relaxation in this material. Specifically, we employ first\nprinciples methods to obtain the basic orbital and spin-orbital properties of\nPtSe$_2$, also in the presence of an external transverse electric field. We\ncalculate the spin mixing parameters $b^2$ and the spin-orbit fields $\\Omega$\nfor the Bloch states of electrons and holes. This information allows us to\npredict the spin lifetimes due to the Elliott-Yafet and D'yakonov-Perel\nmechanisms. We find that $b^2$ is rather large, on the order of $10^{-2}$ and\n$10^{-1}$, while $\\Omega$ varies strongly with doping, being about $10^{3} -\n10^{4}$\\,ns$^{-1}$ for %typical Fermi levels in the interval $(10-100)$ meV,\ncarrier density in the interval $10^{13}-10^{14}$\\,cm$^{-2}$ at the electric\nfield of 1 V/nm. We estimate the spin lifetimes to be on the picosecond level.",
        "positive": "Superfluid response of two-dimensional parahydrogen clusters in\n  confinement: We study by computer simulations the effect of confinement on the superfluid\nproperties of small two-dimensional (2D) parahydrogen clusters. For clusters of\nfewer than twenty molecules, the superfluid response in the low temperature\nlimit is found to remain comparable in magnitude to that of free clusters,\nwithin a rather wide range of depth and size of the confining well. The\nresilience of the superfluid response is attributable to the \"supersolid\"\ncharacter of these clusters. We investigate the possibility of establishing a\nbulk 2D superfluid \"cluster crystal\" phase of \\paraH2, in which a global\nsuperfluid response would arise from tunnelling of molecules across adjacent\nunit cells. The computed energetics suggests that for clusters of about ten\nmolecules, such a phase may be thermodynamically stable against the formation\nof the equilibrium insulating crystal, for values of the cluster crystal\nlattice constant possibly allowing tunnelling across adjacent unit cells"
    },
    {
        "anchor": "Effects of phosphorus-doping upon the electronic structures of single\n  wall carbon nanotubes: The phosphorus-doped single wall carbon nanotube (PSWCNT) is studied by using\nFirst-Principle methods based on Density Function Theory (DFT). The formation\nenergy, total energy, band structure, geometry structure and density of states\nare calculated. It is found that the formation energy of the P-doped single\ncarbon nanotubes increases with diameters; the total energy of carbon nanotubes\nwith the same diameter decreases as the doping rate increases. The effects of\nimpurity position on the im-purity level are discussed. It illustrates that the\nposition of the impurity level may depend on the C-P-C bond angle. According to\nthe above results, it is feasible to substitute a carbon atom with a phosphorus\natom in SWCNT. It is also found that P-doped carbon nanotubes are N type\nsemiconductor.",
        "positive": "Conductance channels of a platform molecule on Au(111) probed with shot\n  noise: The shot noise of the current $I$ through junctions to single\ntrioxatriangulenium cations (TOTA$^+$) on Au(111) is measured with a low\ntemperature scanning tunneling microscope using Au tips. The noise is\nsignificantly reduced compared to the Poisson noise power of $2eI$ and varies\nlinearly with the junction conductance. The data are consistent with electron\ntransmission through a single spin-degenerate transport channel and show that\nTOTA$^+$ in a Au contact does not acquire an unpaired electron. Ab initio\ncalculations reproduce the observations and show that the current involves the\nlowest unoccupied orbital of the molecule and tip states close to the Fermi\nlevel."
    },
    {
        "anchor": "Two-dimensional quantum-dot helium in a magnetic field: Variational\n  theory: A trial wave function for two-dimensional quantum dot helium in an arbitrary\nperpendicular magnetic field (a system of two interacting electrons in a\ntwo-dimensional parabolic confinement potential) is introduced. A key\ningredient of this trial wave function is a Jastrow pair correlation factor\nthat has a displaced Gaussian form. The above choice of the pair correlation\nfactor is instrumental on assuring the overall quality of the wave function at\nall values of the magnetic field.Exact numerical diagonalization results are\nused to gauge the quality of the proposed trial wave function.We find out that\nthis trial wave function is an excellent representation of the true ground\nstate at all values of the magnetic field including weak (or zero) and strong\nmagnetic fields.",
        "positive": "Towards searching for Majorana fermions in topological insulator\n  nanowires: Developing a gate-tunable, scalable, and topologically-protectable\nsupercurrent qubit and integrating it into a quantum circuit are crucial for\napplications in the fields of quantum information technology and topological\nphenomena. Here we propose that the nano-hybrid supercurrent transistors, a\nsuperconducting quantum analogue of a transistor, made of topological insulator\nnanowire would be a promising platform for unprecedented control of both the\nsupercurrent magnitude and the current-phase relation by applying a voltage on\na gate electrode. We believe that our experimental design will help probing\nMajorana state in topological insulator nanowire and establishing a solid-state\nplatform for topological supercurrent qubit."
    },
    {
        "anchor": "Dissipation due to pure spin-current generated by spin pumping: Based on spin-dependent transport theory and thermodynamics, we develop a\ngeneralized theory of the Joule heating in the presence of a spin current.\nAlong with the conventional Joule heating consisting of an electric current and\nelectrochemical potential, it is found that the spin current and spin\naccumulation give an additional dissipation because the spin-dependent\nscatterings inside bulk and ferromagnetic/nonmagnetic interface lead to a\nchange of entropy. The theory is applied to investigate the dissipation due to\npure spin-current generated by spin pumping across a\nferromagnetic/nonmagnetic/ferromagnetic multilayer. The dissipation arises from\nan interface because the spin pumping is a transfer of both the spin angular\nmomentum and the energy from the ferromagnet to conduction electrons near the\ninterface. It is found that the dissipation is proportional to the enhancement\nof the Gilbert damping constant by spin pumping.",
        "positive": "Tunable van Hove Singularities and Correlated States in Twisted Trilayer\n  Graphene: Understanding and tuning correlated states is of great interest and\nsignificance to modern condensed matter physics. The recent discovery of\nunconventional superconductivity and Mott-like insulating states in magic-angle\ntwisted bilayer graphene (tBLG) presents a unique platform to study correlation\nphenomena, in which the Coulomb energy dominates over the quenched kinetic\nenergy as a result of hybridized flat bands. Extending this approach to the\ncase of twisted multilayer graphene would allow even higher control over the\nband structure because of the reduced symmetry of the system. Here, we study\nelectronic transport properties in twisted trilayer graphene (tTLG, bilayer on\ntop of monolayer graphene heterostructure). We observed the formation of van\nHove singularities which are highly tunable by twist angle and displacement\nfield and can cause strong correlation effects under optimum conditions,\nincluding superconducting states. We provide basic theoretical interpretation\nof the observed electronic structure."
    },
    {
        "anchor": "Soliton solutions in the class of implicit difference schemes: We announce a detailed numerical investigation for some class of difference\nschemes, which arises from Euler implicit scheme. Such schemes demonstrate\nunusual behavior and leads to origin of solitons. Applications to some\nnonlinear problems are discussed.",
        "positive": "Superconductivity provides access to the chiral magnetic effect of an\n  unpaired Weyl cone: The massless fermions of a Weyl semimetal come in two species of opposite\nchirality, in two cones of the band structure. As a consequence, the current\n$j$ induced in one Weyl cone by a magnetic field $B$ (the chiral magnetic\neffect, CME) is cancelled in equilibrium by an opposite current in the other\ncone. Here we show that superconductivity offers a way to avoid this\ncancellation, by means of a flux bias that gaps out a Weyl cone jointly with\nits particle-hole conjugate. The remaining gapless Weyl cone and its\nparticle-hole conjugate represent a single fermionic species, with renormalized\ncharge $e^\\ast$ and a single chirality $\\pm$ set by the sign of the flux bias.\nAs a consequence, the CME is no longer cancelled in equilibrium but appears as\na supercurrent response $\\partial j/\\partial B=\\pm(e^\\ast e/h^2)\\mu$ along the\nmagnetic field at chemical potential $\\mu$."
    },
    {
        "anchor": "Generating a second-order topological insulator with multiple corner\n  states by periodic driving: We study the effects of periodic driving on a variant of the\nBernevig-Hughes-Zhang (BHZ) model defined on a square lattice. In the absence\nof driving, the model has both topological and nontopological phases depending\non the different parameter values. We also study the anisotropic BHZ model and\nshow that, unlike the isotropic model, it has a nontopological phase which has\nstates localized on only two of the four edges of a finite-sized square. When\nan appropriate term is added, the edge states get gapped and gapless states\nappear at the four corners of a square; we have shown that these corner states\ncan be labeled by the eigenvalues of a certain operator. When the system is\ndriven periodically by a sequence of two pulses, multiple corner states may\nappear depending on the driving frequency and other parameters. We discuss to\nwhat extent the system can be characterized by topological invariants such as\nthe Chern number and a diagonal winding number. We have shown that the\nlocations of the jumps in these invariants can be understood in terms of the\nFloquet operator at both the time-reversal invariant momenta and other momenta\nwhich have no special symmetries.",
        "positive": "Nonlinear magnetotransport in a dc-current-biased graphene: A balance-equation scheme is developed to investigate the magnetotransport in\na dc-current-biased graphene. We examine the Shubnikov-de Haas oscillation\nunder a nonzero bias current. With an increase in the current density, the\noscillatory differential resistivity exhibits phase inversion, in agreement\nwith recent experimental observation. In the presence of surface optical\nphonons, a second phase inversion may occur at higher dc bias, due to the\nreduced influence of electron-heating and the enhanced direct effect of current\non differential magnetoresistivity. We also predict the appearance of\ncurrent-induced magnetoresistance oscillation in suspended graphene at lower\nmagnetic fields and larger current densities. For the graphene mobility\ncurrently available ($\\approx 20\\,{\\rm m^2/Vs}$), the oscillatory behavior may\nbe somewhat altered by magnetophonon resonance arising from intrinsic acoustic\nphonon under finite bias current condition."
    },
    {
        "anchor": "Compact Modeling of MOSFET I-V Characteristics and Simulation of\n  Dose-Dependent Drain Currents: We have presented a compact MOSFET model, which allows us to describe the I-V\ncharacteristics of irradiated long-channel and short-channel transistors in all\noperation modes at different measurement temperatures and interface trap\ndensities. The model allows simulating of the off-state and the on-state drain\ncurrents of irradiated MOSFETs based on an equal footing. Particularly, a novel\ncompact model of the rebound effect in n-MOSFETs was employed for simulation of\nthe total dose dependencies of drain currents in the highly scaled 60 nm node\ncircuits irradiated up to 1Grad. Compatibility of the model parameter set with\nBSIM and a single closed form of the model equation imply the possibility of\nits easy implementation into the standard CAD tools.",
        "positive": "High-performance nanoscale topological energy transduction: The realization of high-performance, small-footprint, on-chip inductors\nremains a challenge in radio-frequency and power microelectronics, where they\nperform vital energy transduction in filters and power converters. Modern\nplanar inductors consist of metallic spirals that consume significant chip\narea, resulting in low inductance densities. We present a novel method for\nmagnetic energy transduction that utilizes ferromagnetic islands (FIs) on the\nsurface of a 3D time-reversal-invariant topological insulator (TI) to produce\nparadigmatically different inductors. Depending on the chemical potential, the\nFIs induce either an anomalous or quantum anomalous Hall effect in the\ntopological surface states. These Hall effects direct current around the FIs,\nconcentrating magnetic flux and producing a highly inductive device. Using a\nnovel self-consistent simulation that couples AC non-equilibrium Green\nfunctions to fully electrodynamic solutions of Maxwell's equations, we\ndemonstrate excellent inductance densities up to terahertz frequencies, thus\nharnessing the unique properties of topological materials for practical device\napplications."
    },
    {
        "anchor": "Theory of Quantum Light-Matter Interaction in Cavities: Extended Systems\n  and the Long Wavelength Approximation: When light and matter interact strongly, the coupled system inherits\nproperties from both constituents. It is consequently possible to alter the\nproperties of either by engineering the other. This intriguing possibility has\nlead to the emergence of the cavity-materials-engineering paradigm which seeks\nto tailor material properties by engineering the fluctuations of a dark\nelectromagnetic environment. The theoretical description of hybrid light-matter\nsystems is complicated by the combined complexity of a realistic description of\nthe extended electronic and quantum electromagnetic fields. Here we derive an\neffective, non-perturbative theory for low dimensional crystals embedded in a\nparadigmatic Fabry-P\\'erot resonator in the long-wavelength limit. The theory\nencodes the multi-mode nature of the electromagnetic field into an effective\nsingle-mode scheme and it naturally follows from requiring a negligible\nmomentum transfer from the photonic system to the matter. Crucially, in the\neffective theory the single light mode is characterized by a finite effective\nmode volume even in the limit of bulk cavity-matter systems and can be directly\ndetermined by realistic cavity parameters. As a consequence, the coupling of\nthe effective mode to matter remains finite for bulk materials. By leveraging\non the realistic description of the cavity system we make our effective theory\nfree from the double counting of the coupling of matter to the electromagnetic\nvacuum fluctuations of free space. Our results provide a substantial step\ntowards the realistic description of interacting cavity-matter systems at the\nlevel of the fundamental Hamiltonian, by effectively including the\nelectromagnetic environment and going beyond the perfect mirrors approximation.",
        "positive": "Cancellation of quantum anomalies and bosonization of three-dimensional\n  time-reversal symmetric topological insulators: The strong time-reversal symmetric (TRS) topological insulator (TI) in three\nspace dimensions features gapless surface states in the form of massless Dirac\nfermions. We study these surface states with the method of bosonization, and\nfind that the resulting bosonic theory has a topological contribution due to\nthe parity anomaly of the surface Dirac fermions. We argue that the presence of\na quantum anomaly is, in fact, the main reason for the existence of a surface\nstate, by the principle that anomalies of a surface and bulk must cancel.\nInspecting other classes of topological insulators, we argue that this\nprinciple holds in general. Moving beyond purely topological considerations, we\nincorporate the dynamics of the surface electron states into the bosonic\ntheory. Additionally, we discuss the thermodynamics of the bosonic theory and\npropose a representation of the surface Dirac fermions in terms of the bosonic\nfields."
    },
    {
        "anchor": "Dynamical Chiral Nernst Effect in Twisted Van der Waals Few Layers: The Nernst effect is a fundamental thermoelectric conversion phenomenon that\nwas deemed to be possible only in systems with magnetic field or magnetization.\nIn this work, we propose a novel dynamical chiral Nernst effect that can appear\nin two-dimensional van der Waals materials with chiral structural symmetry in\nthe absence of any magnetic degree of freedom. This unconventional effect is\ntriggered by time variation of an out-of-plane electric field, and has an\nintrinsic quantum geometric origin linked to not only the intralayer\ncenter-of-mass motion but also the interlayer coherence of electronic states.\nWe demonstrate the effect in twisted homobilayer and homotrilayer transition\nmetal dichalcogenides, where the strong twisted interlayer coupling leads to\nsizable intrinsic Nernst conductivities well within the experimental capacity.\nThis work suggests a new route for electric control of thermoelectric\nconversion.",
        "positive": "Non-linear dispersive regime of cavity QED: The dressed dephasing model: Systems in the dispersive regime of cavity quantum electrodynamics (QED) are\napproaching the limits of validity of the dispersive approximation. We present\na model which takes into account nonlinear corrections to the dressing of the\natom by the field. We find that in the presence of pure dephasing, photons\npopulating the cavity act as a heat bath on the atom, inducing incoherent\nrelaxation and excitation. These effects are shown to reduce the achievable\nsignal-to-noise ratio in cavity QED realizations where the atom is measured\nindirectly through cavity transmission and in particular in circuit QED."
    },
    {
        "anchor": "Single-band tight-binding parameters for Fe-MgO-Fe magnetic\n  heterostructures: We present a computationally efficient transferable single-band tight-binding\nmodel (SBTB) for spin polarized transport in heterostructures with an effort to\ncapture the band structure effects. As an example, we apply it to study\ntransport through Fe-MgO-Fe(100) magnetic tunnel junction devices. We propose a\nnovel approach to extract suitable tight-binding parameters for a material by\nusing the energy resolved transmission as the benchmark, which inherently has\nthe bandstructure effects over the two dimensional transverse Brillouin zone.\nThe SBTB parameters for each of the four symmetry bands for bcc Fe(100) are\nfirst proposed which are complemented with the transferable tight-binding\nparameters for the MgO tunnel barrier for the Delta_1 and Delta_5 bands. The\nnon-equilibrium Green's function formalism is then used to calculate the\ntransport. Features like I-V characteristics, voltage dependence and the\nbarrier width dependence of the tunnel magnetoresistance ratio are captured\nquantitatively and the trends match well with the ones observed by ab initio\nmethods.",
        "positive": "Monitoring of band gap and magnetic state of graphene nanoribbons\n  through vacancies: Using first-principles plane wave calculations we predict that electronic and\nmagnetic properties of graphene nanoribbons can be affected by defect-induced\nitinerant states. The band gaps of armchair nanoribbons can be modified by\nhydrogen saturated holes. Defects due to periodically repeating vacancy or\ndivacancies induce metallization, as well as magnetization in non-magnetic\nsemiconducting nanoribbons due to the spin-polarization of local defect states.\nAntiferromagnetic ground state of semiconducting zigzag ribbons can change to\nferrimagnetic state upon creation of vacancy defects, which reconstruct and\ninteract with edge states. Even more remarkable is that all these effects of\nvacancy defects are found to depend on their geometry and position relative to\nedges. It is shown that these effects can, in fact, be realized without really\ncreating defects."
    },
    {
        "anchor": "Increased Curie temperature and enhanced perpendicular magneto\n  anisotropy of Cr2Ge2Te6/NiO heterostructure: Magnetism in two-dimensional van der Waals materials has received significant\nattention recently. The Curie temperature reported for those materials,\nhowever, has been so far remained relatively low. Here, we measure\nmagneto-optical Kerr effects (MOKE) under perpendicular magnetic field for van\nder Waals ferromagnet Cr2Ge2Te6 as well as its heterostructure with\nantiferromagnetic insulator NiO. We observe a notable increase in both Curie\ntemperature and magnetic perpendicular anisotropy in Cr2Ge2Te6/NiO\nheterostructures compared to those in Cr2Ge2Te6. Measurements on the same\nexfoliated Cr2Ge2Te6 flake (on a SiO2/Si substrate) before and after depositing\nNiO show that the hysteresis loop can change into a square shape with larger\ncoercive field for Cr2Ge2Te6/NiO. The maximum Curie temperature (TC) observed\nfor Cr2Ge2Te6/NiO reaches ~120 K, is nearly twice the maximum TC ~ 60 K\nreported for Cr2Ge2Te6 alone. Both enhanced perpendicular anisotropy and\nincreased Curie temperature are observed for Cr2Ge2Te6 flakes with a variety of\nthicknesses ranging from ~5 nm to ~200 nm. The results indicate that magnetic\nproperties of two-dimensional van der Waals magnets can be engineered and\ncontrolled by using the heterostructure interface with other materials.",
        "positive": "Noise and Measurement Efficiency of a Partially Coherent Mesoscopic\n  Detector: We study the noise properties and efficiency of a mesoscopic resonant-level\nconductor which is used as a quantum detector, in the regime where transport\nthrough the level is only partially phase coherent. We contrast models in which\ndetector incoherence arises from escape to a voltage probe, versus those in\nwhich it arises from a random time-dependent potential. Particular attention is\npaid to the back-action charge noise of the system. While the average detector\ncurrent is similar in all models, we find that its noise properties and\nmeasurement efficiency are sensitive both to the degree of coherence and to the\nnature of the dephasing source. Detector incoherence prevents quantum limited\ndetection, except in the non-generic case where the source of dephasing is not\nassociated with extra unobserved information. This latter case can be realized\nin a version of the voltage probe model."
    },
    {
        "anchor": "Effects of Geometry and Symmetry on Electron Transport through\n  Graphene-Carbon-Chain Junctions: The electron transport between two zigzag graphene nanoribbons (ZGNRs)\nconnected by carbon atomic chains has been investigated by the nonequilibrium\nGreen's function method combined with the density functional theory. The\nsymmetry of the orbitals in the carbon chain selects critically the modes and\nenergies of the transporting electrons. The electron transport near the Fermi\nenergy can be well-manipulated by the position and the number of carbon chains\ncontacting the nanoribbons. In symmetric ZGNRs connected by a central carbon\nchain, a square conductance step appears at the Fermi energy because the\nantisymmetric modes below it are not allowed to go through the chain. These\nmodes can additionally contribute to the conductance if side carbon chains are\nadded in the connection. By choosing a proper geometry configuration, we can\nrealize Ohmic contact, current stabilizer, or the negative differential\nresistance phenomenon in the devices.",
        "positive": "Fragile topology in line-graph lattices with two, three, or four gapped\n  flat bands: The geometric properties of a lattice can have profound consequences on its\nband spectrum. For example, symmetry constraints and geometric frustration can\ngive rise to topologicially nontrivial and dispersionless bands, respectively.\nLine-graph lattices are a perfect example of both of these features: their\nlowest energy bands are perfectly flat, and here we develop a formalism to\nconnect some of their geometric properties with the presence or absence of\nfragile topology in their flat bands. This theoretical work will enable\nexperimental studies of fragile topology in several types of line-graph\nlattices, most naturally suited to superconducting circuits."
    },
    {
        "anchor": "Topological superconducting phase in helical Shiba chains: Recently, it has been suggested that topological superconductivity and\nMajorana end states can be realized in a chain of magnetic impurities on the\nsurface of an s-wave superconductor when the magnetic moments form a spin helix\nas a result of the RKKY interaction mediated by the superconducting substrate.\nHere, we investigate this scenario theoretically by developing a tight-binding\nBogoliubov-de Gennes description starting from the Shiba bound states induced\nby the individual magnetic impurities. While the resulting model Hamiltonian\nhas similarities with the Kitaev model for one-dimensional spinless p-wave\nsuperconductors, there are also important differences, most notably the\nlong-range nature of hopping and pairing as well as the complex hopping\namplitudes. We use both analytical and numerical approaches to explore the\nconsequences of these differences for the phase diagram and the localization\nproperties of the Majorana end states when the Shiba chain is in a topological\nsuperconducting phase.",
        "positive": "Localized defect modes in graphene: We study the properties of localized vibrational modes associated with\nstructural defects in a sheet of graphene. For the example of the Stone-Wales\ndefects, one- and two-atom vacancies, many-atom linear vacancies, and adatoms\nin a honeycomb lattice, we demonstrate that the local defect modes are\ncharacterized by stable oscillations with the frequencies lying outside the\nlinear frequency bands of an ideal graphene. In the frequency spectral density\nof thermal oscillations, such localized defect modes lead to the additional\npeaks from the right side of the frequency band of the ideal sheet of graphene.\nThus, the general structure of the frequency spectral density can provide a\nfingerprint of its quality and the type of quantity of the structural defect a\ngraphene sheet may contain."
    },
    {
        "anchor": "Hall field induced magnetoresistance oscillations of a two-dimensional\n  electron system: We develop a model of the nonlinear response to a DC electrical current of a\ntwo dimensional electron system(2DES) placed on a magnetic field. Based on the\nexact solution of the Schroedinger equation in arbitrarily strong electric and\nmagnetic fields, and separating the relative and guiding center coordinates, a\nKubo-like formula for the current is worked out as a response to the impurity\nscattering. Self-consistent expressions determine the longitudinal and Hall\ncomponents of the electric field in terms of the DC current. The differential\nresistivity displays strong Hall field-induced oscillations, in agreement with\nthe main features of the phenomenon observed in recent experiments.",
        "positive": "Triplet-Singlet Spin Relaxation via Nuclei in a Double Quantum Dot: The spin of a confined electron, when oriented originally in some direction,\nwill lose memory of that orientation after some time. Physical mechanisms\nleading to this relaxation of spin memory typically involve either coupling of\nthe electron spin to its orbital motion or to nuclear spins. Relaxation of\nconfined electron spin has been previously measured only for Zeeman or exchange\nsplit spin states, where spin-orbit effects dominate relaxation, while spin\nflips due to nuclei have been observed in optical spectroscopy studies. Using\nan isolated GaAs double quantum dot defined by electrostatic gates and direct\ntime domain measurements, we investigate in detail spin relaxation for\narbitrary splitting of spin states. Results demonstrate that electron spin\nflips are dominated by nuclear interactions and are slowed by several orders of\nmagnitude when a magnetic field of a few millitesla is applied. These results\nhave significant implications for spin-based information processing."
    },
    {
        "anchor": "Hydrodynamic study of edge spin-vortex excitations of fractional quantum\n  Hall fluid: We undertake a theoretical study of edge spin-vortex excitations in\nfractional quantum Hall fluid. This is done in view of quantised Euler\nhydrodynamics theory. The dispersions of true excitations for fractions within\n$0\\leq \\nu \\leq 1$ are simulated which exhibit universal similarities and\ndifferences in behaviour. The differences arise from different edge smoothness\nand spin (pseudo-spin) polarisations, in addition to spin-charge competition.\nIn particular, tuning the spin-charge factor causes coherent spin flipping\nassociated with partial and total polarisations of edge spin-vortices. This\nobservation is tipped as an ideal mechanism for realisation of functional\nspintronic devices.",
        "positive": "Excitons in bulk black phosphorus evidenced by photoluminescence at low\n  temperature: Atomic layers of Black Phosphorus (BP) present unique opto-electronic\nproperties dominated by a direct tunable bandgap in a wide spectral range from\nvisible to mid-infrared. In this work, we investigate the infrared\nphotoluminescence of BP single crystals at very low temperature. Near-bandedge\nrecombinations are observed at 2 K, including dominant excitonic transitions at\n0.276 eV and a weaker one at 0.278 eV. The free-exciton binding energy is\ncalculated with an anisotropic Wannier-Mott model and found equal to 9.1 meV.\nOn the contrary, the PL intensity quenching of the 0.276 eV peak at high\ntemperature is found with a much smaller activation energy, attributed to the\nlocalization of free excitons on a shallow impurity. This analysis leads us to\nattribute respectively the 0.276 eV and 0.278 eV PL lines to bound excitons and\nfree excitons in BP. As a result, the value of bulk BP bandgap is refined to\n0.287 eV at 2K."
    },
    {
        "anchor": "Spin Wave Interference Detection via Inverse Spin Hall Effect: In this letter, we present experimental data demonstrating spin wave\ninterference detection using spin Hall effect (ISHE). Two coherent spin waves\nare excited in a yttrium-iron garnet (YIG) waveguide by continuous microwave\nsignals. The initial phase difference between the spin waves is controlled by\nthe external phase shifter. The ISHE voltage is detected at a distance of 2 mm\nand 4 mm away from the spin wave generating antennae by an attached Pt layer.\nExperimental data show ISHE voltage oscillation as a function of the phase\ndifference between the two interfering spin waves. This experiment demonstrates\nan intriguing possibility of using ISHE in spin wave logic circuit converting\nspin wave phase into an electric signal",
        "positive": "Theoretical investigation of the dynamic electronic response of a\n  quantum dot driven by time-dependent voltage: We present a comprehensive theoretical investigation on the dynamic\nelectronic response of a noninteracting quantum dot system to various forms of\ntime-dependent voltage applied to the single contact lead. Numerical\nsimulations are carried out by implementing a recently developed hierarchical\nequations of motion formalism [J. Chem. Phys. 128, 234703 (2008)], which is\nformally exact for a fermionic system interacting with grand canonical\nfermionic reservoirs, in the presence of arbitrary time-dependent applied\nchemical potentials. The dynamical characteristics of the transient transport\ncurrent evaluated in both linear and nonlinear response regimes are analyzed,\nand the equivalent classic circuit corresponding to the coupled dot-lead system\nis also discussed."
    },
    {
        "anchor": "Spin dependent quantum interference in non-local graphene spin valves: Spin dependent electron transport measurements on graphene are of high\nimportance to explore possible spintronic applications. Up to date all spin\ntransport experiments on graphene were done in a semi-classical regime,\ndisregarding quantum transport properties such as phase coherence and\ninterference. Here we show that in a quantum coherent graphene nanostructure\nthe non-local voltage is strongly modulated. Using non-local measurements, we\nseparate the signal in spin dependent and spin independent contributions. We\nshow that the spin dependent contribution is about two orders of magnitude\nlarger than the spin independent one, when corrected for the finite\npolarization of the electrodes. The non-local spin signal is not only strongly\nmodulated but also changes polarity as a function of the applied gate voltage.\nBy locally tuning the carrier density in the constriction we show that the\nconstriction plays a major role in this effect and indicates that it can act as\na spin filter device. Our results show the potential of quantum coherent\ngraphene nanostructures for the use in future spintronic devices.",
        "positive": "Symmetry breaking as the origin of zero-differential resistance states\n  of a 2DEG in strong magnetic fields: Zero resistance differential states have been observed in two-dimensional\nelectron gases (2DEG) subject to a magnetic field and a strong dc current. In a\nrecent work we presented a model to describe the nonlinear transport regime of\nthis phenomenon. From the analysis of the differential resistivity and the\nlongitudinal voltage we predicted the formation of negative differential\nresistivity states, although these states are known to be unstable. Based on\nour model, we derive an analytical approximated expression for the\nVoltage-Current characteristics, that captures the main elements of the\nproblem. The result allow us to construct an energy functional for the system.\nIn the zero temperature limit, the system presents a quantum phase transition,\nwith the control parameter given by the magnetic field. It is noted that above\na threshold value ($B>B_{th}$), the symmetry is spontaneously broken. At\nsufficiently high magnetic field and low temperature the model predicts a phase\nwith a non-vanishing permanent current; this is a novel phase that has not been\nobserved so far."
    },
    {
        "anchor": "Resonant impurities states-driven topological transition in quantum well: We demonstrate theoretically that a new system quantum well can realize the\ntopological transition based on the 16-band kp model. Utilizing the strain\nintroduced by the doped impurities, the band anti crossing induced by the doped\nnitrogen and valence band anti crossing induced by the doped bismuth, the band\ngap of the quantum well is rapidly decreased and even becomes negative. As a\nresult, the topological transitions arise. Furthermore, the band gap as a\nfunction of the concentration of nitrogen and bismuth is calculated, where the\nnegative gap corresponds to the topological phase. Noting the cancel of strain\nresulting from the combination of tensile strain introduced by N and strain\nintroduced by Bi, we can easily tune the ratio of the N and Bi to meet the\nrequirement of strain in the crystal growth procedure. Our proposal provides a\npromising approach for topological insulator in traditional semiconductor\nsystem utilizing the semiconductor fabrication technologies.",
        "positive": "The suppressed radiative recombination rate in a quantum photocell with\n  three electron donors: The radiative recombination of electron-hole pairs represents a great\nchallenge to the photon-to-charge efficiency in the photocell. In this paper,\nwe investigate how to suppress radiative recombination rate (RRR) in a proposed\nquantum photocell with three dipole-dipole coupled and uncoupled electron\ndonors. The results showed that the RRR could be suppressed in this photocell\nwith three uncoupled electron donors but be enhanced with three dipole-dipole\ncoupled electron donors by the ambient circumstance temperatures, and the\nincreasing energy gap in the donors, the decreasing gap between the donors and\nacceptor inhabited the RRR with three dipole-dipole both coupled and uncoupled\nelectron donors. When the photocell was manipulated by the electrostatic\ndipole-dipole coupling strength J at room temperature, the RRR was suppressed\nto a smaller minimum by the gap between the donors and acceptor than those by\ndifferent gaps in the donors. These suppressed strategies for RRR point out\nsome significant ways to increase the photon-to-charge efficiency and deserve\nthe further experimental verification."
    },
    {
        "anchor": "Spin-Hall magnetoresistance in quasi-two-dimensional antiferromagnetic\n  insulator/metal bilayer systems: We study the temperature dependence of spin Hall magnetoresistance (SMR) in\nantiferromagnetic insulator (AFI)/metal bilayer systems. We calculate the\namplitude of the SMR signal by using a quantum Monte Carlo simulation and\nexamine how the SMR depends on the amplitude of the spin, thickness of the AFI\nlayer, and randomness of the exchange interactions. Our results for simple\nquantum spin models provide a useful starting point for understanding SMR\nmeasurements on atomic layers of magnetic compounds.",
        "positive": "Effective lattice model for collective modes in a Fermi liquid with\n  spin-orbit coupling: A Fermi-liquid (FL) with spin-orbit coupling (SOC) supports a special type of\ncollective modes--chiral spin waves--which are oscillations of magnetization\neven in the absence of the external magnetic field. We study the chiral spin\nwaves of a two-dimensional FL in the presence of both the Rashba and\nDresselhaus types of SOC and also subject to the in-plane magnetic field. We\nmap the system of coupled kinetic equations for the angular harmonics of the\noccupation number onto an effective one-dimensional tight-binding model, in\nwhich the lattice sites correspond to angular-momentum channels.\nLinear-in-momentum SOC ensures that the effective tight-binding model has only\nnearest-neighbor hopping on a bipartite lattice. In this language, the\ncontinuum of spin-flip particle-hole excitations becomes a conduction band of\nthe lattice model, whereas electron-electron interaction, parameterized by the\nharmonics of the Landau function, is mapped onto lattice defects of both\non-site and bond type. Collective modes correspond to bound states formed by\nsuch defects. All the features of the collective-mode spectrum receive natural\nexplanation in the lattice picture as resulting from the competition between\non-site and bond defects."
    },
    {
        "anchor": "Distilling one, two and entangled pairs of photons from a quantum dot\n  with cavity QED effects and spectral filtering: A quantum dot can be used as a source of one- and two-photon states and of\npolarisation entangled photon pairs. The emission of such states is\ninvestigated from the point of view of frequency-resolved two-photon\ncorrelations. These follow from a spectral filtering of the dot emission, which\ncan be achieved either by using a cavity or by placing a number of interference\nfilters before the detectors. The combination of these various options is used\nto iteratively refine the emission in a \"distillation\" process and arrive at\nhighly correlated states with a high purity. So-called \"leapfrog processes\"\nwhere the system undergoes a direct transition from the biexciton state to the\nground state by direct emission of two photons, are shown to be central to the\nquantum features of such sources. Optimum configurations are singled out in a\nglobal theoretical picture that unifies the various regimes of operation.",
        "positive": "Structural Transition of Wigner Crystal on Liquid Substrate: The physics of an electron solid, held on a cryogenic liquid surface by a\npressing electric field, is examined in a low-density regime that has not been\nexplored before. We consider the effect of the pressing field in distorting the\nsurface at the position of each electron and hence inducing an attractive force\nbetween the electrons. The system behavior is described in terms of an\ninterplay between the repulsive Coulomb interaction and the attractive\nsurface-induced interaction between individual electrons. For small densities\nand large enough pressing fields, we find a parameter regime where a square\nlattice is more favorable than the usual triangular lattice; we map out the\nfirst-order transition curve separating the two lattice geometries at zero\ntemperature. In addition, our description allows an alternate static\nperspective on the charge-density wave instability of the system, corresponding\nto the formation of multi-electron dimples."
    },
    {
        "anchor": "Quantum coherence in momentum space of light-matter condensates: We show that the use of momentum-space optical interferometry, which avoids\nany spatial overlap between two parts of a macroscopic quantum state, presents\na unique way to study coherence phenomena in polariton condensates. In this\nway, we address the longstanding question in quantum mechanics: \"\\emph{Do two\ncomponents of a condensate, which have never seen each other, possess a\ndefinitive phase?}\" [P. W. Anderson, \\emph{Basic Notions of Condensed Matter\nPhysics} (Benjamin, 1984)]. A positive answer to this question is\nexperimentally obtained here for light-matter condensates, created under\nprecise symmetry conditions, in semiconductor microcavities taking advantage of\nthe direct relation between the angle of emission and the in-plane momentum of\npolaritons.",
        "positive": "Gigahertz Single-Electron Pumping Mediated by Parasitic States: In quantum metrology, semiconductor single-electron pumps are used to\ngenerate accurate electric currents with the ultimate goal of implementing the\nemerging quantum standard of the ampere. Pumps based on electrostatically\ndefined tunable quantum dots (QDs) have thus far shown the most promising\nperformance in combining fast and accurate charge transfer. However, at\nfrequencies exceeding approximately 1 GHz, the accuracy typically decreases.\nRecently, hybrid pumps based on QDs coupled to trap states have led to\nincreased transfer rates due to tighter electrostatic confinement. Here, we\noperate a hybrid electron pump in silicon obtained by coupling a QD to multiple\nparasitic states, and achieve robust current quantization up to a few\ngigahertz. We show that the fidelity of the electron capture depends on the\nsequence in which the parasitic states become available for loading, resulting\nin distinctive frequency dependent features in the pumped current."
    },
    {
        "anchor": "Nonlinear emission of spin-wave caustics from an edge mode of a\n  micro-structured Co2Mn0.6Fe0.4Si waveguide: Magnetic Heusler materials with very low Gilbert damping are expected to show\nnovel magnonic transport phenomena. We report nonlinear generation of higher\nharmonics leading to the emission of caustic spin-wave beams in a low-damping,\nmicro-structured Co2Mn0.6Fe0.4Si Heusler waveguide. The source for the higher\nharmonic generation is a localized edge mode formed by the strongly\ninhomogeneous field distribution at the edges of the spin-wave waveguide. The\nradiation characteristics of the propagating caustic waves observed at twice\nand three times the excitation frequency are described by an analytical\ncalculation based on the anisotropic dispersion of spin waves in a magnetic\nthin film.",
        "positive": "Localized magnetic fields enhance the field-sensitivity of the\n  gyrotropic resonance frequency of a magnetic vortex: We have carried out micromagnetic simulations of the gyrotropic resonance\nmode of a magnetic vortex in the presence of spatially localized and spatially\nuniform out-of-plane magnetic fields. We show that the field-induced change in\nthe gyrotropic mode frequency is significantly larger when the field is\ncentrally localized over lengths which are comparable to or a few times larger\nthan the vortex core radius. When aligned with the core magnetization, such\nfields generate an additional confinement of the core. This confinement\nincreases the vortex stiffness in the small displacement limit, leading to a\nresonance shift which is greater than that expected for a uniform out-of-plane\nfield of the same amplitude. Fields generated by uniformly magnetized spherical\nparticles having a fixed separation from the disk are found to generate\nanalogous effects except that there is a maximum in the shift at intermediate\nparticle sizes where field localization and stray field magnitude combine\noptimally to generate a maximum confinement."
    },
    {
        "anchor": "Reversal of Ferroelectric Polarization by Mechanical Means: Ferroelectric materials are characterized by the presence of an electric\ndipole that can be reversed by application of an external electric field, a\nfeature that is exploited in ferroelectric memories. All ferroelectrics are\npiezoelectric, and therefore exhibit a strong intrinsic coupling between\npolarization and elastic deformation - a feature widely used in piezoelectric\ntransducers and high-displacement actuators. A less explored and exploited\nproperty is flexoelectricity, i.e. the coupling between polarization and a\nstrain gradient. Though flexoelectricity is an old concept (it was discovered\nin the Soviet Union almost 50 years ago), it is only with the advent of\nnanotechnology that its full potential is beginning to be realized, as\ngradients at the nanoscale can be much larger than at the macroscopic scale.\nHere, we demonstrate that the stress gradient generated by the tip of an atomic\nforce microscope can be used to mechanically switch the polarization in the\nnanoscale volume of a ferroelectric film. This observation shows that pure\nmechanical force can be used as a dynamic tool for polarization control,\nenabling information processing in a new type of multiferroic high-density data\nstorage devices where the memory bits are written mechanically and read\nelectrically.",
        "positive": "Conductance of a quantum wire at low electron density: We study the transport of electrons through a long quantum wire connecting\ntwo bulk leads. As the electron density in the wire is lowered, the Coulomb\ninteractions lead to short-range crystalline ordering of electrons. In this\nWigner crystal state the spins of electrons form an antiferromagnetic\nHeisenberg spin chain with exponentially small exchange coupling J.\nInhomogeneity of the electron density due to the coupling of the wire to the\nleads results in violation of spin-charge separation in the device. As a result\nthe spins affect the conductance of the wire. At zero temperature the\nlow-energy spin excitations propagate freely through the wire, and its\nconductance remains 2e^2/h. Since the energy of the elementary excitations in\nthe spin chain (spinons) cannot exceed \\pi J/2, the conductance of the wire\nacquires an exponentially small negative correction \\delta G \\propto - exp(-\\pi\nJ/2T) at low temperatures T<<J. At higher temperatures, T>>J, most of the spin\nexcitations in the leads are reflected by the wire, and the conductance levels\noff at a new universal value e^2/h."
    },
    {
        "anchor": "Spin-momentum locked interaction between guided photons and surface\n  electrons in topological insulators: The propagation of electrons and photons can respectively have the\nspin-momentum locking effect which correlates the spin with the linear\nmomentum. For the surface electrons in three-dimensional topological insulators\n(TIs), their spin is locked to the transport direction. For photons in optical\nfibers and photonic waveguides, they carry transverse spin angular momentum\n(SAM) which is also locked to the propagation direction. A direct connection\nbetween the electronic and the optical spins occurs in TIs with lifted spin\ndegeneracy, which leads to spin-dependent selection rules of optical\ntransitions and results in phenomena such as circular photogalvanic effect\n(CPGE). Here, we demonstrate an optoelectronic device that integrates a TI with\na photonic waveguide. Interaction between the photons in the\ntransverse-magnetic (TM) mode of the waveguide, which carries transverse SAM,\nand the surface electrons in a Bi2Se3 layer generates a directional,\nspin-polarized photocurrent. Because of optical spin-momentum locking, the\ndevice works in a non-reciprocal way such that changing the light propagation\ndirection reverses the photon spin and thus the direction of the photocurrent\nin the TI. This novel device provides a directional interface that directly\nconverts the photon propagation path to the direction and spin polarization of\nthe photo-excited surface current in the TI. It represents a new way of\nimplementing coupled spin-orbit interaction between electrons and photons and\nmay lead to significant applications in opto-spintronics and quantum\ninformation processing.",
        "positive": "Spin Accumulation in Diffusive Conductors with Rashba and Dresselhaus\n  Spin-Orbit Interaction: We calculate the electrically induced spin accumulation in diffusive systems\ndue to both Rashba (with strength $\\alpha)$ and Dresselhaus (with strength\n$\\beta)$ spin-orbit interaction. Using a diffusion equation approach we find\nthat magnetoelectric effects disappear and that there is thus no spin\naccumulation when both interactions have the same strength, $\\alpha=\\pm \\beta$.\nIn thermodynamically large systems, the finite spin accumulation predicted by\nChaplik, Entin and Magarill, [Physica E {\\bf 13}, 744 (2002)] and by Trushin\nand Schliemann [Phys. Rev. B {\\bf 75}, 155323 (2007)] is recovered an\ninfinitesimally small distance away from the singular point $\\alpha=\\pm \\beta$.\nWe show however that the singularity is broadened and that the suppression of\nspin accumulation becomes physically relevant (i) in finite-sized systems of\nsize $L$, (ii) in the presence of a cubic Dresselhaus interaction of strength\n$\\gamma$, or (iii) for finite frequency measurements. We obtain the parametric\nrange over which the magnetoelectric effect is suppressed in these three\ninstances as (i) $|\\alpha|-|\\beta| \\lesssim 1/mL$, (ii)$|\\alpha|-|\\beta|\n\\lesssim \\gamma p_{\\rm F}^2$, and (iii) $|\\alpha|-|\\beta| \\lesssiM\n\\sqrt{\\omega/m p_{\\rm F}\\ell}$ with $\\ell$ the elastic mean free path and\n$p_{\\rm F}$ the Fermi momentum. We attribute the absence of spin accumulation\nclose to $\\alpha=\\pm \\beta$ to the underlying U (1) symmetry. We illustrate and\nconfirm our predictions numerically."
    },
    {
        "anchor": "Higher-order contributions to the Rashba-Bychkov effect with application\n  to Bi/Ag(111) surface alloy: In order to explain the anisotropic Rashba-Bychkov effect observed in several\nmetallic surface-state systems, we use k.p perturbation theory with a simple\ngroup-theoretical analysis and construct effective Rashba Hamiltonians for\ndifferent point groups up to third order in the wavenumber. We perform\nrelativistic ab initio calculations for the Bi/Ag(111) ordered surface alloy\nand from the calculated splitting of the band dispersion we find evidence of\nthe predicted third-order terms. Furthermore, we derive expressions for the\ncorresponding third-order Rashba parameters to provide a simple explanation to\nthe qualitative difference concerning the Rashba-Bychkov splitting of the\nsurface states at Au(111) and Bi/Ag(111).",
        "positive": "Current-induced torques in continuous antiferromagnetic textures: We study the influence of an electric current on a continuous non-collinear\nantiferromagnetic texture. Despite the lack of a net magnetic moment we find\nthat the exchange interaction between conduction electrons and local\nmagnetization generally results in current-induced torques that are similar in\nphenomenology to spin transfer torques in ferromagnets. We present the\ngeneralization of the non-linear sigma model equation of motion for the\nN\\'{e}\\`{e}l vector that includes these current-induced torques, and briefly\ndiscuss the resulting current-induced antiferromagnetic domain wall motion and\nspin-wave Doppler shift. We give an interpretation of our results using a\nunifying picture of current-induced torques in ferromagnets and\nantiferromagnets in which they are viewed as due to the current-induced spin\npolarization resulting from an effective spin-orbit coupling."
    },
    {
        "anchor": "Topological Electrostatics: We present a theory of optimal topological textures in nonlinear sigma-models\nwith degrees of freedom living in the Grassmannian $\\mathrm{Gr}(M,N)$ manifold.\nThese textures describe skyrmion lattices of $N$-component fermions in a\nquantising magnetic field, relevant to the physics of graphene, bilayer and\nother multicomponent quantum Hall systems near integer filling factors $\\nu>1$.\nWe derive analytically the optimality condition, minimizing topological charge\ndensity fluctuations, for a general Grassmannian sigma model $\\mathrm{Gr}(M,N)$\non a sphere and a torus, together with counting arguments which show that for\nany filling factor and number of components there is a critical value of\ntopological charge $d_c$ above which there are no optimal textures. Below $d_c$\na solution of the optimality condition on a torus is unique, while in the case\nof a sphere one has, in general, a continuum of solutions corresponding to new\n{\\it non-Goldstone} zero modes, whose degeneracy is not lifted (via a order\nfrom disorder mechanism) by any fermion interactions depending only on the\ndistance on a sphere. We supplement our general theoretical considerations with\nthe exact analytical results for the case of $\\mathrm{Gr}(2,4)$, appropriate\nfor recent experiments in graphene.",
        "positive": "Rashba precession in quantum wires with interaction: Rashba precession of spins moving along a one-dimensional quantum channel is\ncalculated, accounting for Coulomb interactions. The Tomonaga--Luttinger model\nis formulated in the presence of spin-orbit scattering and solved by\nBosonization. Increasing interaction strength at decreasing carrier density is\nfound to {\\sl enhance} spin precession and the nominal Rashba parameter due to\nthe decreasing spin velocity compared with the Fermi velocity. This result can\nelucidate the observed pronounced changes of the spin splitting on applied gate\nvoltages which are estimated to influence the interface electric field in\nheterostructures only little."
    },
    {
        "anchor": "Thermal switching rate of a ferromagnetic material with uniaxial\n  anisotropy: The field dependence of the thermal switching rate of a ferromagnetic\nmaterial with uniaxial anisotropy was studied by solving the Fokker-Planck\nequation. We derived the analytical expression of the thermal switching rate\nusing the mean first-passage time approach, and found that Brown's formula\n[Phys. Rev. 130, 1677 (1963)] is applicable even in the low barrier limit by\nreplacing the attempt frequency with the proper factor which is expressed by\nthe error function.",
        "positive": "Dynamics revealed by correlations of time-distributed weak measurements\n  of a single spin: We show that the correlations in stochastic outputs of time-distributed weak\nmeasurements can be used to study the dynamics of an individual quantum object,\nwith a proof-of-principle setup based on small Faraday rotation caused by a\nsingle spin in a quantum dot. In particular, the third order correlation can\nreveal the \"true\" spin decoherence, which would otherwise be concealed by the\ninhomogeneous broadening effect in the second order correlations. The viability\nof such approaches lies in that (1) in weak measurement the state collapse\nwhich would disturb the system dynamics occurs at a very low probability, and\n(2) a shot of measurement projecting the quantum object to a known basis state\nserves as a starter or stopper of the evolution without pumping or coherently\ncontrolling the system as otherwise required in conventional spin echo."
    },
    {
        "anchor": "Silicon-based molecular switch junctions: In contrast to the static operations of conventional semiconductor devices,\nthe dynamic conformational freedom in molecular devices opens up the\npossibility of using molecules as new types of devices such as a molecular\nconformational switch or for molecular data storage. Bistable molecules, with\ne.g. two stable cis and trans isomeric configurations, could provide, once\nclamped between two electrodes, a switching phenomenon in the nonequilibrium\ncurrent response. Here, we model molecular switch junctions formed at silicon\ncontacts and demonstrate the potential of tunable molecular switches in\nelectrode/molecule/electrode configurations. Using the non equilibrium Green\nfunction approach implemented with the density-functional-based tight-binding\ntheory, a series of properties such as electron transmissions, I-V\ncharacteristics in the different isomer-conformations, and potential energy\nsurfaces as a function of the reaction coordinates along the trans to cis\ntransition were calculated. Furthermore, in order to investigate stability of\nmolecular switches in ambient conditions, molecular dynamics (MD) simulations\nat room temperature were performed and time- dependent fluctuations of the\nconductance along the MD pathways were calculated. Our numerical results show\nthat the transmission spectra of the cis isomers are more conductive than trans\ncounterparts inside the bias window for all two model molecules. The\ncurrent-voltage characteristics consequently show the same trends.\nAdditionally, the calculations of time-dependent transmission fluctuations\nalong the MD pathways have shown that the transmission in cis isomers is always\nsignificantly larger than that of trans counterparts showing that molecular\nswitches can be expected to work as robust molecular switching components.",
        "positive": "Spin Dynamics with Inertia in Metallic Ferromagnets: Non-adiabatic contribution of environmental degrees of freedom yields\neffective inertia of spin in effective spin dynamics. In this paper, we study\nseveral aspects of the inertia of spin in metallic ferromagnets. (i) a concrete\nexpression of the spin inertia $m_s$: $m_s=\\hbar S_c/(2g_{\\rm sd})$, where\n$S_c$ is the spin polarization of conduction electrons and $g_{\\rm sd}$ is the\n$sd$ coupling constant. (ii) dynamical behavior of spin with inertia, discussed\nfrom viewpoints of a spinning top and of a particle on a sphere. (iii) behavior\nof spin waves and domain walls in the presence of inertia, and behavior of spin\nwith inertia in the case of a time-dependent magnetic field."
    },
    {
        "anchor": "Long-range photon-mediated gate scheme between nuclear spin qubits in\n  diamond: Defect centers in diamond are exceptional solid-state quantum systems that\ncan have exceedingly long electron and nuclear spin coherence times. So far,\nsingle-qubit gates for the nitrogen nuclear spin, a two-qubit gate with a\nnitrogen-vacancy (NV) center electron spin, and entanglement between nearby\nnitrogen nuclear spins have been demonstrated. Here, we develop a scheme to\nimplement a universal two-qubit gate between two distant nitrogen nuclear\nspins. Virtual excitation of an NV center that is embedded in an optical cavity\ncan scatter a laser photon into the cavity mode; we show that this process\ndepends on the nuclear spin state of the nitrogen atom. If two NV centers are\nsimultaneously coupled to a common cavity mode and individually excited,\nvirtual cavity photon exchange can mediate an effective interaction between the\nnuclear spin qubits, conditioned on the spin state of both nuclei, which\nimplements a universal controlled-$\\textit{Z}$ gate. We predict operation times\nbelow 100 nanoseconds, which is several orders of magnitude faster than the\ndecoherence time of nuclear spin qubits in diamond.",
        "positive": "In-situ study of oxygen exposure effect on spin-orbit torque in Pt/Co\n  bilayers in ultrahigh vacuum: Oxygen incorporation has been reported to increase the current-induced\nspin-orbit torque in ferromagnetic heterostructures, but the underlying\nmechanism is still under active debate. Here, we report on an in-situ study of\nthe oxygen exposure effect on spin-orbit torque in Pt/Co bilayers via\ncontrolled oxygen exposure, Co and Mg deposition, and electrical measurements\nin ultrahigh vacuum. We show that the oxygen exposure on Pt/Co indeed leads to\nan increase of spin-orbit torque, but the enhancement is not as large as those\nreported previously. Similar enhancement of spin-orbit torque is also observed\nafter the deposition of an MgO capping layer. The results of ab initio\ncalculations on the Rashba splitting of Pt/Co and Pt/Co/O suggest that the\nenhancement is due to enhanced Rashba-Edelstein effect by surface-adsorbed\noxygen. Our findings shed some light on the varying roles of oxygen in\nmodifying the spin torque efficiency reported previously."
    },
    {
        "anchor": "Phase Structure of the Topological Anderson Insulator: We study the disordered topological Anderson insulator in a 2-D (square not\nstrip) geometry. We first report the phase diagram of finite systems and then\nstudy the evolution of phase boundaries when the system size is increased to a\nvery large $1120 \\times 1120$ area. We establish that conductance quantization\ncan occur without a bulk band gap, and that there are two distinct scaling\nregions with quantized conductance: TAI-I with a bulk band gap, and TAI-II with\nlocalized bulk states. We show that there is no intervening insulating phase\nbetween the bulk conduction phase and the TAI-I and TAI-II scaling regions, and\nthat there is no metallic phase at the transition between the quantized and\ninsulating phases. Centered near the quantized-insulating transition there are\nvery broad peaks in the eigenstate size and fractal dimension $d_2$; in a large\nportion of the conductance plateau eigenstates grow when the disorder strength\nis increased. The fractal dimension at the peak maximum is $d_2 \\approx 1.5$.\nEffective medium theory (CPA, SCBA) predicts well the boundaries and interior\nof the gapped TAI-I scaling region, but fails to predict all boundaries save\none of the ungapped TAI-II scaling region. We report conductance distributions\nnear several phase transitions and compare them with critical conductance\ndistributions for well-known models.",
        "positive": "Synchronization theory of microwave induced zero-resistance states: We develop the synchronization theory of microwave induced zero-resistance\nstates (ZRS) for two-dimensional electron gas in a magnetic field. In this\ntheory the dissipative effects lead to synchronization of cyclotron phase with\ndriving microwave phase at certain resonant ratios between microwave and\ncyclotron frequencies. This synchronization produces stabilization of electron\ntransport along edge channels and at the same time it gives suppression of\ndissipative scattering on local impurities and dissipative conductivity in the\nbulk, thus creating the ZRS phases at that frequency ratios. The electron\ndynamics along edge and around circular disk impurity is well described by the\nChirikov standard map. The theoretical analysis is based on extensive numerical\nsimulations of classical electron transport in a strongly nonlinear regime. We\nalso discuss the value of activation energy obtained in our model and the\nexperimental signatures that could establish the synchronization origin of ZRS."
    },
    {
        "anchor": "Electrical Contacts to Carbon Nanotubes Down to 1nm in Diameter: Rhodium (Rh) is found similar to Palladium (Pd) in making near-ohmic\nelectrical contacts to single-walled carbon nanotubes (SWNTs) with diameters d\n> ~ 1.6 nm. Non-negligible positive Schottky barriers (SBs) exist between Rh or\nPd and semiconducting SWNTs (S-SWNTs) with d < ~ 1.6 nm. With Rh and Pd\ncontacts, the characteristics of SWNT field-effect transistors (FETs) and SB\nheights at the contacts are largely predictable based on the SWNT diameters,\nwithout random variations among devices. Surprisingly, electrical contacts to\nmetallic SWNTs (M-SWNTs) also appear to be diameter dependent especially for\nsmall SWNTs. Ohmic contacts are difficult for M-SWNTs with diameters < ~ 1.0 nm\npossibly due to tunnel barriers.",
        "positive": "Transport studies of dual-gated ABC and ABA trilayer graphene: band gap\n  opening and band structure tuning in very large perpendicular electric field: We report on the transport properties of ABC and ABA stacked trilayer\ngraphene using dual, locally gated field effect devices. The high efficiency\nand large breakdown voltage of the HfO2 top and bottom gates enables\nindependent tuning of the perpendicular electric field and the Fermi level over\nan unprecedentedly large range. We observe a resistance change of six orders of\nmagnitude in the ABC trilayer, which demonstrates the opening of a band gap.\nOur data suggest that the gap saturates at a large displacement field of D ~ 3\nV/nm, in agreement with self-consistent Hartree calculations. In contrast, the\nABA trilayer remains metallic even under a large perpendicular electric field.\nDespite the absence of a band gap, the band structure of the ABA trilayer\ncontinues to evolve with increasing D. We observe signatures of two-band\nconduction at large D fields. Our self-consistent Hartree calculation\nreproduces many aspects of the experimental data, but also points to the need\nfor more sophisticated theory."
    },
    {
        "anchor": "Shot noise in non-adiabatically driven nanoscale conductors: We investigate the noise properties of pump currents through molecular wires\nand coupled quantum dots. As a model we employ a two level system that is\nconnected to electron reservoirs and is non-adiabatically driven. Concerning\nthe electron-electron interaction, we focus on two limits: non-interacting\nelectrons and strong Coulomb repulsion. While the former case is treated within\na Floquet scattering formalism, we derive for the latter case a master equation\nformalism for the computation of the current and the zero-frequency noise. For\na pump operated close to internal resonances, the differences between the\nnon-interacting and the strongly interacting limit turn out to be surprisingly\nsmall.",
        "positive": "Field-induced low-temperature electronic specific heat of boron nitride\n  nanotubes: We use the tight-binding model to study the effect of transverse electric\nfield on the low-temperature electronic specific heat (Cv) for armchair and\nzigzag boron nitride nanotubes (ABNNTs and ZBNNTs). For wide-band-gap BNNTs,\nelectric field could significantly modulate their energy dispersions and shift\nmany electronic states close to the Fermi energy. Under a critical electric\nfield (Fc) the density of states show special peak structures and the vanishing\nspecific heat at zero field jumps to a giant one. Cv, at Fc's, has a value\ncomparable to that of the phonon specific heat and reveals strongly non-linear\ndependence on temperature. The critical field strength and the value of giant\nspecific heat are closely related to nanotube's geometry. In the presence of\nFc's, the extra longitudinal magnetic flux could enhance the value of Cv again\nat low temperature for ZBNNTs, whereas it is not always true for ABNNTs."
    },
    {
        "anchor": "Quantum state readout of individual quantum dots by electrostatic force\n  detection: Electric charge detection by atomic force microscopy (AFM) with single-\nelectron resolution (e-EFM) is a promising way to investigate the electronic\nlevel structure of individual quantum dots (QD). The oscillating AFM tip\nmodulates the energy of the QDs, causing single electrons to tunnel between QDs\nand an electrode. The resulting oscillating electrostatic force changes the\nresonant frequency and damping of the AFM cantilever, enabling electrometry\nwith a single-electron sensitivity. Quantitative electronic level spectroscopy\nis possible by sweeping the bias voltage. Charge stability diagram can be\nobtained by scanning the AFM tip around the QD. e-EFM technique enables to\ninvestigate individual colloidal nanoparticles and self- assembled QDs without\nnanoscale electrodes. e-EFM is a quantum electromechanical system where the\nback-action of a tunneling electron is detected by AFM; it can also be\nconsidered as a mechanical analog of admittance spectroscopy with a radio\nfrequency resonator, which is emerging as a promising tool for quantum state\nreadout for quantum computing. In combination with the topography imaging\ncapability of the AFM, e-EFM is a powerful tool for investigating new nanoscale\nmaterial systems which can be used as quantum bits.",
        "positive": "Coulomb interactions at quantum Hall critical points of systems in a\n  periodic potential: We study the consequences of long-range Coulomb interactions at the critical\npoints between integer/fractional quantum Hall states and an insulator. We use\nlow energy theories for such transitions in anyon gases in the presence of an\nexternal periodic potential. We find that Coulomb interactions are marginally\nirrelevant for the integer quantum Hall case. For the fractional case,\ndepending upon the anyon statistics parameter, we find behavior similar to the\ninteger case, or flow to a novel line of fixed points with exponents $z=1$,\n$\\nu > 1$ stable against weak disorder in the position of the critical point,\nor run-away flow to strong coupling."
    },
    {
        "anchor": "Non-equilibrium transport through a point contact in the $\u03bd=5/2$\n  non-Abelian quantum Hall state: We analyze charge-$e/4$ quasiparticle tunneling between the edges of a point\ncontact in a non-Abelian model of the $\\nu=5/2$ quantum Hall state. We map this\nproblem to resonant tunneling between attractive Luttinger liquids and use the\ntime-dependent density-matrix renormalization group (DMRG) method to compute\nthe current through the point contact in the presence of a {\\it finite voltage\ndifference} between the two edges. We confirm that, as the voltage is\ndecreases, the system is broken into two pieces coupled by electron hopping. In\nthe limits of small and large voltage, we recover the results expected from\nperturbation theory about the infrared and ultraviolet fixed points. We test\nour methods by finding the analogous non-equilibrium current through a point\ncontact in a $\\nu=1/3$ quantum Hall state, confirming the Bethe ansatz solution\nof the problem.",
        "positive": "Landau quantization and equatorial states on a surface of a nanosphere: The Landau quantization for the electron gas on a surface of sphere is\nconsidered. We show that in the regime of strong fields the lowest energy\nstates are those with magnetic quantum numbers m of order of Phi/Phi_0, the\nnumber of magnetic flux quanta piercing the sphere. For the electron gas of low\ndensity (semiconducting situation), it leads to the formation of the electronic\nstripe on the equator of the sphere in high fields."
    },
    {
        "anchor": "The Lowest Landau Level Anyon Equation of State in the Anti-screening\n  Regime: The thermodynamics of the anyon model projected on the lowest Landau level\n(LLL) of an external magnetic field is addressed in the anti-screening regime,\nwhere the flux tubes carried by the anyons are parallel to the magnetic field.\nIt is claimed that the LLL-anyon equation of state, which is known in the\nscreening regime, can be analytically continued in the statistical parameter\nacross the Fermi point to the antiscreening regime up to the vicinity (whose\nwidth tends to zero when the magnetic field becomes infinite) of the Bose\npoint. There, an unphysical discontinuity arises due to the dropping of the\nnon-LLL eigenstates which join the LLL, making the LLL approximation no longer\nvalid. However, taking into account the effect of the non-LLL states at the\nBose point would only smoothen the discontinuity and not alter the physics\nwhich is captured by the LLL projection: Close to the Bose point, the critical\nfilling factor either goes to infinity (usual bosons) in the screening\nsituation, or to 1/2 in the anti-screening situation, the difference between\nthe flux tubes orientation being relevant even when they carry an infinitesimal\nfraction of the flux quantum. An exclusion statistics interpretation is\nadduced, which explains this situation in semiclassical terms. It is further\nshown how the exact solutions of the 3-anyon problem support this scenario as\nfar as the third cluster coefficient is concerned.",
        "positive": "Landau Quantized Dynamics and Spectrum of the Diced Lattice: In this work the role of magnetic Landau quantization in the dynamics and\nspectrum of Diced Lattice charge carriers is studied in terms of the associated\npseudospin 1 Green's function. The equations of motion for the 9 matrix\nelements of this Green's function are formulated in position/frequency\nrepresentation and are solved explicitly in terms of a closed form integral\nrepresentation involving only elementary functions. The latter is subsequently\nexpanded in a Laguerre eigenfunction series whose frequency poles identify the\ndiscretized energy spectrum for the Landau-quantized Diced Lattice as\n$\\epsilon_n = \\pm\\sqrt{2(2n+1)\\alpha^2 eB}$ ($\\alpha\\sqrt{2}$ is the\ncharacteristic speed for the Diced Lattice) which differs significantly from\nthe nonrelativistic linear dependence of $\\epsilon_n$ on $B$, and is similar to\nthe corresponding $\\sqrt{B}-$dependence of other Dirac materials (Graphene,\nGroup VI Dichalcogenides)."
    },
    {
        "anchor": "Suppression of Multilayer Graphene Patches during CVD Graphene growth on\n  Copper: By limiting the carbon segregation at the copper surface defects, a pulsed\nchemical vapor deposition method for single layer graphene growth is shown to\ninhibit the formation of few-layer regions, leading to a fully single-layered\ngraphene homogeneous at the centimeter scale. Graphene field-effect devices\nobtained after transfer of pulsed grown graphene on oxidized silicon exhibit\nmobilities above 5000 cm^2.V^-1.s^-1.",
        "positive": "Role of pseudospin in quasiparticle interferences in epitaxial graphene\n  probed by high-resolution scanning tunneling microscopy: Pseudospin, an additional degree of freedom related to the honeycomb\nstructure of graphene, is responsible of many of the outstanding electronic\nproperties found in this material. This article provides a clear understanding\nof how such pseudospin impacts the quasiparticle interferences of monolayer\n(ML) and bilayer (BL) graphene measured by low temperature scanning tunneling\nmicroscopy and spectroscopy. We have used this technique to map, with very high\nenergy and space resolution, the spatial modulations of the local density of\nstates of ML and BL graphene epitaxialy grown on SiC(0001), in presence of\nnative disorder. We perform a Fourier transform analysis of such modulations\nincluding wavevectors up to unit-vectors of the reciprocal lattice. Our data\ndemonstrate that the quasiparticle interferences associated to some particular\nscattering processes are suppressed in ML graphene, but not in BL graphene.\nMost importantly, interferences with 2qF wavevector associated to intravalley\nbackscattering are not measured in ML graphene, even on the images with highest\nresolution. In order to clarify the role of the pseudospin on the quasiparticle\ninterferences, we use a simple model which nicely captures the main features\nobserved on our data. The model unambiguously shows that graphene's pseudospin\nis responsible for such suppression of quasiparticle interferences features in\nML graphene, in particular for those with 2qF wavevector. It also confirms\nscanning tunneling microscopy as a unique technique to probe the pseudospin in\ngraphene samples in real space with nanometer precision. Finally, we show that\nsuch observations are robust with energy and obtain with great accuracy the\ndispersion of the \\pi-bands for both ML and BL graphene in the vicinity of the\nFermi level, extracting their main tight binding parameters."
    },
    {
        "anchor": "Determining the vibrations between sensor and sample in SQUID microscopy: Vibrations can cause noise in scanning probe microscopies. Relative\nvibrations between the scanning sensor and the sample are important but can be\nmore difficult to determine than absolute vibrations or vibrations relative to\nthe laboratory. We measure the noise spectral density in a scanning SQUID\nmicroscope as a function of position near a localized source of magnetic field,\nand show that we can determine the spectra of all three components of the\nrelative sensor-sample vibrations. This method is a powerful tool for\ndiagnosing vibrational noise in scanning microscopies.",
        "positive": "Modification of spintronic terahertz emitter performance through defect\n  engineering: Spintronic ferromagnetic/non-magnetic heterostructures are novel sources for\nthe generation of THz radiation based on spin-to-charge conversion in the\nlayers. The key technological and scientific challenge of THz spintronic\nemitters is to increase their intensity and frequency bandwidth. Our work\nreveals the factors to engineer spintronic Terahertz generation by introducing\nthe scattering lifetime and the interface transmission for spin polarized,\nnon-equilibrium electrons. We clarify the influence of the electron-defect\nscattering lifetime on the spectral shape and the interface transmission on the\nTHz amplitude, and how this is linked to structural defects of bilayer\nemitters. The results of our study define a roadmap of the properties of\nemitted as well as detected THz-pulse shapes and spectra that is essential for\nfuture applications of metallic spintronic THz emitters."
    },
    {
        "anchor": "Strain-induced pseudomagnetic field and quantum oscillations in kagome\n  crystals: A kagome lattice is composed of corner-sharing triangles arranged on a\nhoneycomb lattice such that each honeycomb bond hosts a kagome site while each\nkagome triangle encloses a honeycomb site. Such close relation implies that the\ntwo lattices share common features. We predict here that a kagome crystal,\nsimilar to the honeycomb lattice graphene, reacts to elastic strain in a unique\nway that the bulk electronic states in the vicinity of Dirac points are\nreorganized by the strain-induced pseudomagnetic field into flat Landau levels,\nwhile the degenerate edge states in the undeformed crystal become separated in\nthe energy dimension. When the strain is tuned continuously, the resulting\nscanning pseudomagnetic field gives rise to quantum oscillations in both\ndensity of states (DOS) and electric conductivity.",
        "positive": "Weak values under uncertain conditions: We analyze the average of weak values over statistical ensembles of pre- and\npost-selected states. The protocol of weak values, proposed by Aharonov et al.,\nis the result of a weak measurement conditional on the outcome of a subsequent\nstrong (projective) measurement. Weak values can be beyond the range of\neigenvalues of the measured observable and, in general, can be complex numbers.\nWe show that averaging over ensembles of pre- and post-selected states reduces\nthe weak value within the range of eigenvalues of the measured operator. We\nfurther show that the averaged result expressed in terms of pre- and\npost-selected density matrices, allows us to include the effect of decoherence."
    },
    {
        "anchor": "Quantum oscillations of spin current through a III-V semiconductor loop: We have investigated the transport of spin polarization through a classically\nchaotic semiconductor loop with a strong Rashba spin-orbit interaction. We\nfound that if the escape time of a particle is long enough, the configuration\naveraged spin conductance oscillates strongly with the geometric spin phase. We\npredict a sizable rotation of spin polarization along its flowing path across\nthe loop from the injector to the collector. We have also discovered a\nquantized universal spin relaxation in a 2D reservoir connected to such a\nsemiconductor loop.",
        "positive": "Scattering resonances in graphene: We address the two-dimensional band-structure of graphene above the vacuum\nlevel in the context of discrete states immersed in the three-dimensional\ncontinuum. Scattering resonances are discovered that originate from the\ncoupling of the in-plane and perpendicular motions, as elucidated by the\nanalysis of an exactly solvable model. Some of the resonances turn into true\nbound states at high-symmetry $\\kv$ vectors. {\\it Ab initio} scattering theory\nverifies the existence of the resonances in realistic graphene and shows that\nthey lead to a total reflection of the incident electron below and total\ntransmission above the resonance energy."
    },
    {
        "anchor": "Supersymmetry and Unconventional Quantum Hall Effect in Graphene: We present a unified description of the quantum Hall effect in graphene on\nthe basis of the 8-component Dirac Hamiltonian and the supersymmetric (SUSY)\nquantum mechanics. It is remarkable that the zero-energy state emerges because\nthe Zeeman splitting is exactly as large as the Landau level separation, as\nimplies that the SUSY is a good symmetry. For nonzero energy states, the\nup-spin state and the down-spin state form a supermultiplet possessing the spin\nSU(2) symmetry. We extend the Dirac Hamiltonian to include two indices\n$j_{\\uparrow}$ and $j_{\\downarrow}$, characterized by the dispersion relation\n$E(p) \\propto p^{j_{\\uparrow}+j_{\\downarrow}}$ and the Berry phase $\\pi\n(j_{\\uparrow}-j_{\\downarrow})$. The quantized Hall conductivity is shown to be\n$\\sigma_{xy}=\\pm (2n+j_{\\uparrow}+j_{\\downarrow}) 2e^{2}/h$.",
        "positive": "Circuits and excitations to enable Brownian token-based computing with\n  skyrmions: Brownian computing exploits thermal motion of discrete signal carriers\n(tokens) for computations. In this paper we address two major challenges that\nhinder competitive realizations of circuits and application of Brownian\ntoken-based computing in actual devices for instance based on magnetic\nskyrmions. To overcome the problem that crossings generate for the fabrication\nof circuits, we design a crossing-free layout for a composite half-adder\nmodule. This layout greatly simplifies experimental implementations as wire\ncrossings are effectively avoided. Additionally, our design is shorter to speed\nup computations compared to conventional designs. To address the key issue of\nslow computation based on thermal excitations, we propose to overlay artificial\ndiffusion induced by an external excitation mechanism. For instance, if\nmagnetic skyrmions are used as tokens, artificially induced diffusion by\nspin-orbit torques or other mechanisms increases the speed of computations by\nseveral orders of magnitude. Combined with conventional Brownian computing the\nlatter could greatly enhance the application scenarios of token-based computing\nfor instance for low power devices such as autonomous sensors with limited\npower that is harvested from the environment."
    },
    {
        "anchor": "Renormalization group analysis of thermal transport in the disordered\n  Fermi liquid: We present a detailed study of thermal transport in the disordered Fermi\nliquid with short-range interactions. At temperatures smaller than the impurity\nscattering rate, i.e., in the diffusive regime, thermal conductivity acquires\nnon-analytic quantum corrections. When these quantum corrections become large\nat low temperatures, the calculation of thermal conductivity demands a\ntheoretical approach that treats disorder and interactions on an equal footing.\nIn this paper, we develop such an approach by merging Luttinger's idea of using\ngravitational potentials for the analysis of thermal phenomena with a\nrenormalization group calculation based on the Keldysh nonlinear sigma model.\nThe gravitational potentials are introduced in the action as auxiliary sources\nthat couple to the heat density. These sources are a convenient tool for\ngenerating expressions for the heat density and its correlation function from\nthe partition function. Already in the absence of the gravitational potentials,\nthe nonlinear sigma model contains several temperature-dependent\nrenormalization group charges. When the gravitational potentials are introduced\ninto the model, they acquire an independent renormalization group flow. We show\nthat this flow preserves the phenomenological form of the correlation function,\nreflecting its relation to the specific heat and the constraints imposed by\nenergy conservation. The main result of our analysis is that the\nWiedemann-Franz law holds down to the lowest temperatures even in the presence\nof disorder and interactions and despite the quantum corrections that arise for\nboth the electric and thermal conductivities.",
        "positive": "Constructing 100 M\u03a9 and 1 G\u03a9 Resistance Standards via\n  Star-Mesh Transformations: A recent mathematical framework for optimizing resistor networks to achieve\nvalues in the M{\\Omega} through G{\\Omega} levels was employed for two specific\ncases. Objectives here include proof of concept and identification of possible\napparatus limitations for future experiments involving graphene-based quantum\nHall array resistance standards. Using fractal-like, or recursive, features of\nthe framework allows one to calculate and implement network designs with\nsubstantially lower-valued resistors. The cases of 100 M{\\Omega} and 1\nG{\\Omega} demonstrate that, theoretically, one would not need more than 100\nquantum Hall elements to achieve these high resistances."
    },
    {
        "anchor": "Metallization of Nanofilms in Strong Adiabatic Electric Fields: We introduce an effect of metallization of dielectric nanofilms by strong,\nadiabatically varying electric fields. The metallization causes optical\nproperties of a dielectric film to become similar to those of a plasmonic metal\n(strong absorption and negative permittivity at low optical frequencies). The\nis a quantum effect, which is exponentially size-dependent, occurring at fields\non the order of 0.1 V/A and pulse durations ranging from ~ 1 fs to ~ 10 ns for\nfilm thickness 3 to 10 nm.",
        "positive": "Feasibility of imaging using Boltzmann polarization in nuclear Magnetic\n  Resonance Force Microscopy: We report on Magnetic Resonance Force Microscopy measurements of the\nBoltzmann polarization of the nuclear spins in copper by detecting the\nfrequency shift of a soft cantilever. We use the time-dependent solution of the\nBloch equations to derive a concise equation describing the effect of rf\nmagnetic fields on both on- and off-resonant spins in high magnetic field\ngradients. We then apply this theory to saturation experiments performed on a\n100 nm thick layer of copper, where we use the higher modes of the cantilever\nas source of the rf field. We demonstrate a detection volume sensitivity of\nonly (40 nm)$^3$, corresponding to about 1.6$\\cdot 10^4$ polarized copper\nnuclear spins. We propose an experiment on protons where, with the appropriate\ntechnical improvements, frequency-shift based magnetic resonance imaging with a\nresolution better than (10 nm)$^3$ could be possible. Achieving this resolution\nwould make imaging based on the Boltzmann polarization competitive with the\nmore traditional stochastic spin-fluctuation based imaging, with the\npossibility to work at milliKelvin temperatures."
    },
    {
        "anchor": "Interplay of disorder and interaction in Majorana quantum wires: We study the interplay between disorder and interaction in one-dimensional\ntopological superconductors which carry localized Majorana zero-energy states.\nUsing Abelian bosonization and the perturbative renormalization group (RG)\napproach, we obtain the RG-flow and the associated scaling dimensions of the\nparameters and identify the critical points of the low-energy theory. We\npredict a quantum phase transition from a topological superconducting phase to\na non-topological localized phase, and obtain the phase boundary between these\ntwo phases as a function of the electron-electron interaction and the disorder\nstrength in the nanowire. Based on an instanton analysis which incorporates the\neffect of disorder, we also identify a large regime of stability of the\nMajorana-carrying topological phase in the parameter space of the model.",
        "positive": "Inelastic neutron scattering and frequency domain magnetic resonance\n  studies of S=4 and S=12 Mn$_6$ single-molecule magnets: We investigate the magnetic properties of three Mn$_6$ single molecule\nmagnets by means of inelastic neutron scattering and frequency domain magnetic\nresonance spectroscopy. The experimental data reveal that small structural\ndistortions of the molecular geometry produce a significant effect on the\nenergy level diagram and therefore on the magnetic properties of the molecule.\nWe show that the giant spin model completely fails to describe the spin level\nstructure of the ground spin multiplets. We analyze theoretically the spin\nHamiltonian for the low spin Mn$_6$ molecule (S=4) and we show that the excited\n$S$ multiplets play a key role in determining the effective energy barrier for\nthe magnetization reversal, in analogy to what was previously found for the two\nhigh spin Mn6 (S=12) molecules [S. Carretta et al., Phys. Rev. Lett. 100,\n157203 (2008)]."
    },
    {
        "anchor": "Theory of spin precession monitored by laser pulse: We first predict the splitting of a spin degenerate impurity level when this\nimpurity is irradiated by a circularly polarized laser beam tuned in the\ntransparency region of a semiconductor. This splitting, which comes from\ndifferent exchange processes between the impurity electron and the virtual\npairs coupled to the pump beam, induces a spin precession around the laser beam\naxis, which lasts as long as the pump pulse. It can thus be used for ultrafast\nspin manipulation. This effect, which has similarities with the exciton optical\nStark effect we studied long ago, is here derived using the concepts we\ndeveloped very recently to treat many-body interactions between composite\nexcitons and which make the physics of this type of effects quite transparent.\nThey, in particular, allow to easily extend this work to other experimental\nsituations in which a spin rotates under laser irradiation.",
        "positive": "On-column 2p bound state with topological charge \\pm1 excited by an\n  atomic-size vortex beam in an aberration-corrected scanning transmission\n  electron microscope: Atomic-size vortex beams have great potential in probing materials' magnetic\nmoment at atomic scales. However, the limited depth of field of vortex beams\nconstrains the probing depth in which the helical phase front is preserved. On\nthe other hand, electron channeling in crystals can counteract beam divergence\nand extend the vortex beam without disrupting its topological charge.\nSpecifically, in this paper, we report atomic vortex beams with topological\ncharge \\pm1 can be coupled to the 2p columnar bound states and propagate for\nmore 50 nm without being dispersed and losing its helical phase front. We gave\nnumerical solutions to the 2p columnar orbitals and tabulated the\ncharacteristic size of the 2p states of two typical elements, Co and Dy, for\nvarious incident beam energies and various atomic densities. The tabulated\nnumbers allow estimates of the optimal convergence angle for maximal coupling\nto 2p columnar orbital. We also have developed analytic formulae for beam\nenergy, convergence-angle, and hologram dependent scaling for various\ncharacteristic sizes. These length scales are useful for the design of\npitch-fork apertures and operations of microscopes in the vortex-beam imaging\nmode."
    },
    {
        "anchor": "Hybrid Spin Noise Spectroscopy and the Spin Hall Effect: Here we suggest a novel hybrid spin noise spectroscopy technique, which is\nsensitive to the spin Hall effect. It is shown that, while the standard\nspin-spin correlation function is not sensitive to the spin Hall effect,\nspin-transverse voltage and transverse voltage-voltage correlation functions\nprovide the missing sensitivity being linear and quadratic in the spin Hall\ncoefficient, respectively. The correlation between transverse voltage and spin\nfluctuations appears as a result of spin-charge coupling fundamental for the\nspin Hall effect. We anticipate that the proposed method could find\napplications in the studies of spin-charge coupling in semiconductors.",
        "positive": "Particle and thermal transport through one dimensional topological\n  systems via Lindblad formalism: We apply the Lindblad quantum master equation to two examples of\none-dimensional topological systems, the Su-Schrieffer-Heeger (SSH) model and\nKitaev chain, to study their particle and thermal transport. The steady-state\nproperties are obtained by decomposing fermions into Majorana fermions and\nextracting their correlation functions. We focus on the particle and thermal\ncurrents flowing through the bulk when the system is driven by two reservoirs\ncoupled to the two ends. The ratio of the currents of the SSH model from the\ntopological and trivial regimes with the same bandwidth demonstrates\nsuppression of transport due to the edge states, which couple to the reservoirs\nbut do not participate in transport. A similar comparison cannot be performed\nfor the Kitaev chain because the topological and trivial regimes have different\nbandwidths, and the edge states are less significant away from the transition.\nTherefore, the results contrast various topological properties in quantum\ntransport."
    },
    {
        "anchor": "Non-equilibrium entanglement in a driven Dicke model: We study the entanglement dynamics in the externally-driven single-mode Dicke\nmodel in the thermodynamic limit, when the field is in resonance with the\natoms. We compute the correlations in the atoms-field ground state by means of\nthe density operator that represents the pure state of the universe and the\nreduced density operator for the atoms, which results from taking the partial\ntrace over the field coordinates. As a measure of bipartite entanglement, we\ncalculate the linear entropy, from which we analyze the entanglement dynamics.\nIn particular, we found a strong relation between the stability of the\ndynamical parameters and the reported entanglement.",
        "positive": "Deformations of the spin currents by topological screw dislocation and\n  cosmic dispiration: We study the spin currents induced by topological screw dislocation and\ncosmic dispiration. By using the extended Drude model, we find that the spin\ndependent forces are modified by the nontrivial geometry. For the topological\nscrew dislocation, only the direction of spin current is bended by deforming\nthe spin polarization vector. In contrast, the force induced by cosmic\ndispiration could affect both the direction and magnitude of the spin current.\nAs a consequence, the spin-Hall conductivity doesn't receive corrections from\nscrew dislocation."
    },
    {
        "anchor": "Peculiarities of the stochastic motion in antiferromagnetic\n  nanoparticles: Antiferromagnetic (AFM) materials are widely used in spintronic devices as\npassive elements (for stabilization of ferromangetic layers) and as active\nelements (for information coding). In both cases switching between the\ndifferent AFM states depends in a great extent from the environmental noise. In\nthe present paper we derive the stochastic Langevin equations for an AFM vector\nand corresponding Fokker-Planck equation for distribution function in the phase\nspace of generalised coordinate and momentum. Thermal noise is modeled by a\nrandom delta-correlated magnetic field that interacts with the dynamic\nmagnetisation of AFM particle. We analyse in details a particular case of the\ncollinear compensated AFM in the presence of spin-polarised current. The energy\ndistribution function for normal modes in the vicinity of two equilibrium\nstates (static and stationary) in sub- and super-critical regimes is found. It\nis shown that the noise-induced dynamics of AFM vector has pecuilarities\ncompared to that of magnetisation vector in ferromagnets.",
        "positive": "Energy spectrum reconstruction at the edge of a two-dimensional electron\n  system with strong spin-orbit coupling: We experimentally demonstrate the simultaneous reconstruction of the bulk and\nthe edge energy spectra caused by strong spin-orbit interaction, at the two\nlowest filling factors $\\nu=1$ and $\\nu=2$ for $In_xGa_{1-x}As$ two-dimensional\nelectron system with $x = 0.75$. The observed reconstruction is of different\ncharacter at these filling factors: it is characterized by zeroing of the\nenergy gap at the levels crossing point at $\\nu=2$, while the reconstruction at\n$\\nu=1$ goes through the coexistence of two $\\nu=1$ quantum Hall phases with\ndifferent spin projections. An analysis indicates a strong influence of\nmany-body interaction on the reconstruction at $\\nu=1$."
    },
    {
        "anchor": "Anomalous Aharonov-Bohm conductance oscillations from topological\n  insulator surface states: We study transport properties of a topological insulator nanowire when a\nmagnetic field is applied along its length. We predict that with strong surface\ndisorder, a characteristic signature of the band topology is revealed in\nAharonov Bohm (AB) oscillations of the conductance. These oscillations have a\ncomponent with anomalous period $\\Phi_0=hc/e$, and with conductance maxima at\nodd multiples of $\\frac12\\Phi_0$, i.e. when the AB phase for surface electrons\nis $\\pi$. This is intimately connected to the band topology and a surface\ncurvature induced Berry phase, special to topological insulator surfaces. We\ndiscuss similarities and differences from recent experiments on Bi$_2$Se$_3$\nnanoribbons, and optimal conditions for observing this effect.",
        "positive": "The self-consistent calculation of the edge states at quantum Hall\n  effect (QHE) based Mach-Zehnder interferometers (MZI): The spatial distribution of the incompressible edge states (IES) is obtained\nfor a geometry which is topologically equivalent to an electronic Mach-Zehnder\ninterferometer, taking into account the electron-electron interactions within a\nHartree type self-consistent model. The magnetic field dependence of these IES\nis investigated and it is found that an interference pattern may be observed if\ntwo IES merge or come very close, near the quantum point contacts. Our\ncalculations demonstrate that, being in a quantized Hall plateau does not\nguarantee observing the interference behavior."
    },
    {
        "anchor": "Self-sustained current oscillations in the kinetic theory of\n  semiconductor superlattices: We present the first numerical solutions of a kinetic theory description of\nself-sustained current oscillations in n-doped semiconductor superlattices. The\ngoverning equation is a single-miniband Boltzmann-Poisson transport equation\nwith a BGK (Bhatnagar-Gross-Krook) collision term. Appropriate boundary\nconditions for the distribution function describe electron injection in the\ncontact regions. These conditions seamlessly become Ohm's law at the injecting\ncontact and the zero charge boundary condition at the receiving contact when\nintegrated over the wave vector. The time-dependent model is numerically solved\nfor the distribution function by using the deterministic Weighted Particle\nMethod. Numerical simulations are used to ascertain the convergence of the\nmethod. The numerical results confirm the validity of the Chapman-Enskog\nperturbation method used previously to derive generalized drift-diffusion\nequations for high electric fields because they agree very well with numerical\nsolutions thereof.",
        "positive": "Spin- and band-ferromagnetism in trilayer graphene: We study the ground state properties of an ABA-stacked trilayer graphene. The\nlow energy band structure can be described by a combination of both a linear\nand a quadratic particle-hole symmetric dispersions, reminiscent of monolayer-\nand bilayer-graphene, respectively. The multi-band structure offers more\nchannels for instability towards ferromagnetism when the Coulomb interaction is\ntaken into account. Indeed, if one associates a pseudo-spin 1/2 degree of\nfreedom to the bands (parabolic/linear), it is possible to realize also a\nband-ferromagnetic state, where there is a shift in the energy bands, since\nthey fill up differently. By using a variational procedure, we compute the\nexchange energies for all possible variational ground states and identify the\nparameter space for the occurrence of spin- and band-ferromagnetic\ninstabilities as a function of doping and interaction strength."
    },
    {
        "anchor": "Electron transport in crossed nanotubes with point contact: The electron transport in a four-terminal nanodevice consisting of two\ncrossed nanotubes is investigated in the framework of the Landauer-Buttiker\nformalism. The evident formula for the ballistic conductance of the device is\nfound using a model of crossed conductive cylinders with a point contact\nbetween them. Sharp conductance dips stipulated by resonance scattering on the\ncontact are shown to appear in the conductance of the first cylinder. The\nconductance between the cylinders has resonant behavior. The form and the\nposition of resonant peaks are studied. Our results indicate that the form of\nasymmetric dips and peaks in the conductance differs from the well-known Fano\nline shape. We have shown that the maximal value of the conductance between\ncylinders does not exceed a unit of the conductance quantum.",
        "positive": "Gate-controlled valley transport and Goos-H\u00e4nchen effect in\n  monolayer WS$_2$: Based on a Dirac-like Hamiltonian and coherent scattering formalism, we study\nspin-valley transport and Goos-H\\\"{a}nchen like (GHL) effect of transmitted and\nreflected electrons in a gated monolayer WS$_2$. Our results show that the\nlateral shift of spin-polarized electrons is strongly dependent on the width of\nthe gated region and can be positive or negative in both Klein tunneling and\nclassical motion regimes. The absolute values of the lateral displacements at\nresonance positions can be considerably enhanced when the incident angle of\nelectrons is close to the critical angle. In contrast to the time reversal\nsymmetry for the transmitted electrons, the GHL shift of the reflected beams is\nnot invariant under simultaneous interchange of spins and valleys, indicating\nthe lack of spin-valley symmetry induced by the tunable potential barrier on\nWS$_2$ monolayer. Our findings provide evidence for electrical control of\nvalley filtering and valley beam splitting by tuning the incident angle of\nelectrons in nanoelectronic devices based on monolayer transition metal\ndichalcogenides."
    },
    {
        "anchor": "Quantum $RLC$ circuits: charge discreteness and resonance: In a recent article, we have advanced a semiclassical theory of quantum\ncircuits with discrete charge and electrical resistance. In this work, we\npresent a few elementary applications of this theory. For the zero resistance,\ninductive circuit, we obtain the Stark ladder energies in yet another way; and\ngeneralize earlier results by Chandia et. al, for the circuit driven by a\ncombination d.c. plus a.c. electromotive force (emf). As a second application,\nwe investigate the effect of electrical resistance, together with charge\ndiscreteness, in the current amplitude, and resonance conditions of a general\n$RLC$ quantum circuit, including nonlinear effects up to third order on the\nexternal sinusoidal emf.",
        "positive": "Negative differential resistance in nanoscale transport in the Coulomb\n  blockade: Motivated by recent experiments, we have studied transport behavior of\ncoupled quantum dot systems in the Coulomb blockade regime using the master\n(rate) equation approach. We explore how electron-electron interactions in a\ndonor-acceptor system, resembling weakly coupled quantum dots with varying\ncharging energy, can modify the systems response to an external bias, taking it\nfrom normal Coulomb blockade behavior to negative differential resistance (NDR)\nin the curent-voltage characteristics."
    },
    {
        "anchor": "Interplay of Ehrenfest time and dephasing time in ballistic conductors: Quantum interference corrections in ballistic conductors require a minimal\ntime: the Ehrenfest time. In this letter, we investigate the fate of the\ninterference corrections to quantum transport in bulk ballistic conductors if\nthe Ehrenfest time and the dephasing time are comparable.",
        "positive": "Synthesis of Multifunctional Charge Transfer Agents: Towards Single\n  Walled Carbon Nanotubes with Defined Covalent Functionality and Preserved\n  \u03c0 System: The attachment of well-defined charge transfer agents to the surface of\nnanomaterials is an efficient strategy to control their charge density and also\nto tune their optical, electrical, and physicochemical properties. Particularly\ninteresting are charge transfer agents that either donate or withdraw electrons\ndepending on the arrangements of their building units and that promise a\nnon-destructive attachment to delicate nanomaterials like sp$^2$ compounds. In\nthis work, we rationally synthesize molecular moieties with versatile\nfunctionalities. A reactive anchor group allows to attach them to carbon\nnanotubes as defined charge transfer agents while preserving the tube\n$\\pi$-conjugation. The charge transfer agents were synthesized through the\nstepwise nucleophilic substitution of either one (monosubstituted series) or\ntwo chlorine (disubstituted series) atoms of cyanuric chloride by aniline\nderivatives containing one, two or three methoxy groups in the para and meta\npositions. Variation in the number and position of methoxy as an electron\ntransferring group help us to manipulate the electronic and optical properties\nof the molecular probes and their charge transfer to the SWNTs systematically.\nThe correlation between the optical properties of these molecular probes and\ntheir functionality was investigated by experiments and quantum chemical\ncalculations. While the optoelectronic properties of the conjugated charge\ntransfer agents were dominated by the aniline segments, the triazine warrants\nthe ability to nondestructively attach to the surface of SWNTs. This study is\none step ahead towards the production of SWNTs with desired optical and\nelectrical properties by covalent $\\pi$-preserving functionalization."
    },
    {
        "anchor": "Ultrafast manipulation of electron spins in a double quantum dot device:\n  A real-time view: We consider a double quantum dot system with two embedded and non-aligned\nspin impurities to manipulate the magnitude and polarization of the electron\nspin density. The device is attached to semi-infinite one-dimensional leads\nwhich are treated exactly. We provide a real-time description of the electron\nspin dynamics when a sequence of ultrafast voltage pulses acts on the device.\nThe numerical simulations are carried out using a spin generalized and modified\nversion of a recently proposed algorithm for the time propagation of open\nsystems [Phys. Rev. B {\\bf 72}, 035308 (2005)]. Time-dependent spin\naccumulations and spin currents are calculated during the entire operating\nregime which includes spin injection and read-out processes. The full knowledge\nof the electron dynamics allows us to engineer the transient responses and\nimprove the device performance. An approximate rate equation for the electron\nspin is also derived and used to discuss the numerical results.",
        "positive": "Stationary phase approximation approach to the quasiparticle\n  interference on the surface of a strong topological insulator: Topological insulators have surface states with unique spin-orbit coupling.\nWith impurities on the surface, the quasiparticle interference pattern is an\neffective way to reveal the topological nature of the surface states, which can\nbe probed by the scanning tunneling microscopy. In this paper, we present a\ngeneral analytic formulation of the local density of states using the\nstationary phase approximation. The power laws of Friedel oscillations are\ndiscussed for a constant energy contour with a generic shape. In particular, we\npredict unique signature of magnetic impurities in comparison with nonmagnetic\nimpurities for a surface state trapped in a \"magnetic wall\"."
    },
    {
        "anchor": "Unified formulation of interfacial magnonic pumping from non-collinear\n  magnets: We establish a general formulation for spin current pumped by magnons at the\ninterface between a normal metal and a magnetic insulator, valid for any\nnon-collinear magnetic configuration in the linear spin wave regime. This\ncurrent is generated by driving the system in a non-equilibrium state, covering\nsetups such as thermal spin injection (spin Seebeck effect) or spin voltage by\nirradiation of the insulator (spin pumping). We illustrate the formula in the\nspecial case of a honeycomb topological ferromagnet, for simplicity, and cover\nboth the spin Seebeck and spin-pumping setups. We show how the topological\nparameters influence the spin current and propose a way to obtain a\ncontribution mainly from the topological edge magnons in the spin pumping case.",
        "positive": "Double single-channel Kondo coupling in graphene with Fe molecules: We study the interaction between graphene and a single-molecule-magnet,\n[Fe4(L)2(dpm)6]. Focusing on the closest Iron ion in a hollow position with\nrespect to the graphene sheet, we derive a channel selective tunneling\nHamiltonian, that couples different d orbitals of the Iron atom to precise\nindependent combinations of sublattice and valley degrees of freedom of the\nelectrons in graphene. When looking at the spin-spin interaction between the\nmolecule and the graphene electrons, close to the Dirac point the channel\nselectivity results in a channel decoupling of the Kondo interaction, with two\nalmost independent Kondo systems weakly interacting among themselves. The\nformation of magnetic moments and the development of a full Kondo effect\ndepends on the charge state of the graphene layer."
    },
    {
        "anchor": "Reentrant behavior of the phase stiffness in Josephson junction arrays: The phase diagram of a 2D Josephson junction array with large substrate\nresistance, described by a quantum XY model, is studied by means of Fourier\npath-integral Monte Carlo. A genuine Berezinskii-Kosterlitz-Thouless transition\nis found up to a threshold value g* of the quantum coupling, beyond which no\nphase coherence is established. Slightly below g* the phase stiffness shows a\nreentrant behavior with temperature, in connection with a low-temperature\ndisappearance of the superconducting phase, driven by strong nonlinear quantum\nfluctuations.",
        "positive": "Critical length limiting super-low friction: Since the demonstration of super-low friction (superlubricity) in graphite at\nnanoscale, one of the main challenges in the field of nano- and micro-mechanics\nwas to scale this phenomenon up. A key question to be addressed is to what\nextent superlubricity could persist, and what mechanisms could lead to its\nfailure. Here, using an edge-driven Frenkel-Kontorova model, we establish a\nconnection between the critical length above which superlubricity disappears\nand both intrinsic material properties and experimental parameters. A striking\nboost in dissipated energy with chain length emerges abruptly due to a\nhigh-friction stick-slip mechanism caused by deformation of the slider leading\nto a local commensuration with the substrate lattice. We derived a\nparameter-free analytical model for the critical length that is in excellent\nagreement with our numerical simulations. Our results provide a new perspective\non friction and nano-manipulation and can serve as a theoretical basis for\ndesigning nano-devices with super-low friction, such as carbon nanotubes."
    },
    {
        "anchor": "Strain sensing with sub-micron sized Al-AlOx-Al tunnel junctions: We demonstrate a local strain sensing method for nanostructures based on\nmetallic Al tunnel junctions with AlOx barriers. The junctions were fabricated\non top of a thin silicon nitride membrane, which was actuated with an AFM tip\nattached to a stiff cantilever. A large relative change in the tunneling\nresistance in response to the applied strain (gauge factor) was observed, up to\na value 37. This facilitates local static strain variation measurements down to\n~10^{-7}.",
        "positive": "Landau-Lifshitz theory of the longitudinal spin Seebeck effect: Thermal-bias-induced spin angular momentum transfer between a paramagnetic\nmetal and ferromagnetic insulator is studied theoretically based on the\nstochastic Landau-Lifshitz-Gilbert (LLG) phenomenology. Magnons in the\nferromagnet establish a nonequilibrium steady state by equilibrating with\nphonons via bulk Gilbert damping and electrons in the paramagnet via spin\npumping, according to the fluctuation-dissipation theorem. Subthermal magnons\nand the associated spin currents are treated classically, while the appropriate\nquantum crossover is imposed on high-frequency magnetic fluctuations. We\nidentify several length scales in the ferromagnet, which govern qualitative\nchanges in the dependence of the thermally-induced spin current on the magnetic\nfilm thickness."
    },
    {
        "anchor": "Direct Comparison of Fractional and Integer Quantized Hall Resistance: We present precision measurements of the fractional quantized Hall effect\nwhere the quantized resistance $R^{[1/3]}$ in the fractional quantum Hall state\nat filling factor 1/3 was compared with a quantized resistance $R^{[2]}$,\nrepresented by an integer quantum Hall state at filling factor 2. A cryogenic\ncurrent comparator bridge capable of currents down to the nanoampere range was\nused to directly compare two resistance values of two GaAs-based devices\nlocated in two cryostats. A value of $1 - (5.3 \\pm 6.3) 10^{-8}$ (95%\nconfidence level) was obtained for the ratio $(R^{[1/3]}/6R^{[2]})$. This\nconstitutes the most precise comparison of integer resistance quantization (in\nterms of $h/e^2$) in single-particle systems and of fractional quantization in\nfractionally charged quasi-particle systems. While not relevant for practical\nmetrology, such a test of the validity of the underlying physics is of\nsignificance in the context of the up-coming revision of the SI.",
        "positive": "Planckian properties of 2D semiconductor systems: We describe and discuss the low-temperature resistivity (and the\ntemperature-dependent inelastic scattering rate) of several different doped 2D\nsemiconductor systems from the perspective of the Planckian hypothesis\nasserting that $\\hbar/\\tau =k_\\mathrm{B}T$ provides a scattering bound, where\n$\\tau$ is the appropriate relaxation time. The regime of transport considered\nhere is well-below the Bloch-Gruneisen regime so that phonon scattering is\nnegligible. The temperature-dependent part of the resistivity is almost\nlinear-in-$T$ down to arbitrarily low temperatures, with the linearity arising\nfrom an interplay between screening and disorder, connected with carrier\nscattering from impurity-induced Friedel oscillations. The temperature\ndependence disappears if the Coulomb interaction between electrons is\nsuppressed. The temperature coefficient of the resistivity is enhanced at lower\ndensities, enabling a detailed study of the Planckian behavior both as a\nfunction of the materials system and carrier density. Although the precise\nPlanckian bound never holds, we find somewhat surprisingly that the bound seems\nto apply approximately with the scattering rate never exceeding $k_\\mathrm{B}\nT$ by more than an order of magnitude either in the experiment or in the\ntheory. In addition, we calculate the temperature-dependent electron-electron\ninelastic scattering rate by obtaining the temperature-dependent self-energy\narising from Coulomb interaction, also finding it to obey the Planckian bound\nwithin an order of magnitude at all densities and temperatures. We introduce\nthe concept of a generalized Planckian bound where $\\hbar/\\tau$ is bounded by\n$\\alpha k_\\mathrm{B} T$ with $\\alpha\\sim 10$ or so in the super-Planckian\nregime with the strict Planckian bound of $\\alpha$=1 being a nongeneric\nfinetuned situation."
    },
    {
        "anchor": "Influence of the electron density on the thickness-dependent energy gap\n  oscillations in superconducting metallic nanofilms: The thickness-dependent energy gap oscillations in the metallic nanofilms are\ninvestigated by the use of the self-consistent numerical solutions of the\nBogoliubov-de Gennes equations. It is shown, that the oscillations are induced\nby the quasi-particle energy quantization triggered by the confinement of\nelectrons in the direction perpendicular to the sample. We have analyzed, how\nthe changes in the electron density of states ($n_e$) and the electron-phonon\ncoupling constant ($g$) influence the amplitude of the considered oscillations.\nIt has been found, that the increase in $n_e$ and the decrease in $g$, can lead\nto a significant reduction of the oscillations amplitude. As a result, for the\nvalues of the mentioned parameters corresponding to some of the realistic\nsituations the thickness-dependent superconducting gap oscillations can be\nalmost completely suppressed.",
        "positive": "Quasiclassical approach to the spin-Hall effect in the two-dimensional\n  electron gas: We study the spin-charge coupled transport in a two-dimensional electron\nsystem using the method of quasiclassical ($\\xi$-integrated) Green's functions.\nIn particular we derive the Eilenberger equation in the presence of a generic\nspin-orbit field. The method allows us to study spin and charge transport from\nballistic to diffusive regimes and continuity equations for spin and charge are\nautomatically incorporated. In the clean limit we establish the connection\nbetween the spin-Hall conductivity and the Berry phase in momentum space. For\nfinite systems we solve the Eilenberger equation numerically for the special\ncase of the Rashba spin-orbit coupling and a two-terminal geometry. In\nparticular, we calculate explicitly the spin-Hall induced spin polarization in\nthe corners, predicted by Mishchenko et al. [13]. Furthermore we find universal\nspin currents in the short-time dynamics after switching on the voltage across\nthe sample, and calculate the corresponding spin-Hall polarization at the\nedges. Where available, we find perfect agreement with analytical results."
    },
    {
        "anchor": "Polar optical phonons in core-shell semiconductor nanowires: We obtain the the long-wavelength polar optical vibrational modes of\nsemiconductor core-shell nanowires by means of a phenomenological continuum\nmodel. A basis for the space of solutions is derived, and by applying the\nappropriate boundary conditions, the transcendental equations for the coupled\nand uncoupled modes are attained. Our results are applied to the study of the\nGaAs-GaP core-shell nanowire, for which we calculate numerically the polar\noptical modes, analyzing the role of strain in the vibrational properties of\nthis nanosystem.",
        "positive": "Dynamical properties of quasiparticles in a tunable Kekul\u00e9 graphene\n  superlattice: We investigate the dynamical properties of quasiparticles in graphene\nsuperlattices with three typical Kekul\\'{e} distortions (i.e., Kekul\\'{e}-O,\nKekul\\'{e}-Y and Kekul\\'{e}-M). On the one hand, we numerically show the\nvisualized evolution process of Kekul\\'{e} quasiparticles; while on the other\nhand, we analytically obtain the centroid trajectory of the quasiparticles, and\nboth of them agree well with each other. The results reveal that the\nrelativistic Zitterbewegung (ZB) phenomenon occurs in the Kekul\\'{e} systems.\nFurthermore, through analyzing the frequency of ZB, we unveil the one-to-one\nrelationship between ZB and Kekul\\'{e} textures, i.e., the ZB frequenies of\nKekul\\'{e}-O, Kekul\\'{e}-Y and Kekul\\'{e}-M quasiparticles feature single,\ndouble and six frequencies, respectively. Finally, we propose a scheme to\ndistinguish among different Kekul\\'{e} textures from the dynamical perspective.\nThe predictions in this paper are expected to be experimentally verified in the\nnear future, so as to facilitate further research of Kekul\\'{e} structures in\nsolid materials or artificial systems."
    },
    {
        "anchor": "Efficient phonon cascades in hot photoluminescence of WSe$_2$ monolayers: Energy relaxation of photo-excited charge carriers is of significant\nfundamental interest and crucial for the performance of monolayer (1L)\ntransition metal dichaclogenides (TMDs) in optoelectronics. We measure light\nscattering and emission in 1L-WSe$_2$ close to the laser excitation energy\n(down to~$\\sim$0.6meV). We detect a series of periodic maxima in the hot\nphotoluminescence intensity, stemming from energy states higher than the\nA-exciton state, in addition to sharp, non-periodic Raman lines related to the\nphonon modes. We find a period $\\sim$15meV for peaks both below (Stokes) and\nabove (anti-Stokes) the laser excitation energy. We detect 7 maxima from 78K to\nroom temperature in the Stokes signal and 5 in the anti-Stokes, of increasing\nintensity with temperature. We assign these to phonon cascades, whereby\ncarriers undergo phonon-induced transitions between real states in the\nfree-carrier gap with a probability of radiative recombination at each step. We\ninfer that intermediate states in the conduction band at the $\\Lambda$-valley\nof the Brillouin zone participate in the cascade process of 1L-WSe$_2$. The\nobservations explain the primary stages of carrier relaxation, not accessible\nso far in time-resolved experiments. This is important for optoelectronic\napplications, such as photodetectors and lasers, because these determine the\nrecovery rate and, as a consequence, the devices' speed and efficiency.",
        "positive": "Magneto-transport and domain wall scattering in epitaxy $L1_{0}$ MnAl\n  thin film: This work demonstrated two different kinds of magneto-transport behaviors in\nepitaxial $L1_{0}$ MnAl film as a function of temperature. The\nmagneto-resistance ratio (MR) was negative and exhibited evident enhancement in\nthe resistivity at coercive fields above 175 K. The MR enhancement was\nattributed to the increase of the magnetic domain walls based on the\nquantitative correlation between the domain density and the resistivity. Below\n175 K, the MR was positive and showed a quadratic dependence on the external\nmagnetic field, which implied that the MR was dominated by Lorentz effects."
    },
    {
        "anchor": "Velocity Autocorrelation Function of Magnetized Two-Dimensional\n  One-Component Plasma: The velocity autocorrelation function (VAF) for a two-dimensional\none-component plasma (OCP) is investigated by employing molecular dynamics\ntechniques. The VAF exhibits well defined oscillations whose frequency is\nindependent of the dimensionless coupling parameter Gamma. However, the\npresence of a uniform perpendicular external magnetic field increases the\nheight of the first peak. Molecular dynamics computer simulation results are\npresented for a two-dimensional OCP in a perpendicular magnetic field as a\nfunction of the Plasma parameter. Our simulation results clearly indicate that\nat high temperature, the magnetic field affects the VAF in a substantial way.",
        "positive": "Evidence for Superlattice Dirac Points and Space-dependent Fermi\n  Velocity in Corrugated Graphene Monolayer: Recent studies show that periodic potentials can generate superlattice Dirac\npoints at energies in graphene (is the Fermi velocity of graphene and G is the\nreciprocal superlattice vector). Here, we perform scanning tunneling microscopy\nand spectroscopy studies of a corrugated graphene monolayer on Rh foil. We show\nthat the quasi-periodic ripples of nanometer wavelength in the corrugated\ngraphene give rise to weak one-dimensional (1D) electronic potentials and\nthereby lead to the emergence of the superlattice Dirac points. The position of\nthe superlattice Dirac point is space-dependent and shows a wide distribution\nof values. We demonstrated that the space-dependent superlattice Dirac points\nis closely related to the space-dependent Fermi velocity, which may arise from\nthe effect of the local strain and the strong electron-electron interaction in\nthe corrugated graphene."
    },
    {
        "anchor": "Spin states and persistent currents in mesoscopic rings: spin-orbit\n  interactions: We investigate theoretically electron spin states in one dimensional (1D) and\ntwo dimensional (2D) hard-wall mesoscopic rings in the presence of both the\nRashba spin-orbit interaction (RSOI) and the Dresselhaus spin-orbit interaction\n(DSOI) in a perpendicular magnetic field. The Hamiltonian of the RSOI alone is\nmathematically equivalent to that of the DSOI alone using an SU(2) spin\nrotation transformation. Our theoretical results show that the interplay\nbetween the RSOI and DSOI results in an effective periodic potential, which\nconsequently leads to gaps in the energy spectrum. This periodic potential also\nweakens and smoothens the oscillations of the persistent charge current (CC)\nand spin current (SC) and results in the localization of electrons. For a 2D\nring with a finite width, higher radial modes destroy the periodic oscillations\nof persistent currents.",
        "positive": "Microscopic theory for quantum mirages in quantum corrals: Scanning tunneling microscopy permits to image the Kondo resonance of a\nsingle magnetic atom adsorbed on a metallic surface. When the magnetic impurity\nis placed at the focus of an elliptical quantum corral, a Kondo resonance has\nbeen recently observed both on top of the impurity and on top of the focus\nwhere no magnetic impurity is present. This projection of the Kondo resonance\nto a remote point on the surface is referred to as quantum mirage. We present a\nquantum mechanical theory for the quantum mirage inside an ideal quantum corral\nand predict that the mirage will occur in corrals with shapes other than\nelliptical."
    },
    {
        "anchor": "Time-linear quantum transport simulations with correlated nonequilibrium\n  Green's functions: We present a time-linear scaling method to simulate open and correlated\nquantum systems out of equilibrium. The method inherits from many-body\nperturbation theory the possibility to choose selectively the most relevant\nscattering processes in the dynamics, thereby paving the way to the real-time\ncharacterization of correlated ultrafast phenomena in quantum transport. The\nopen system dynamics is described in terms of an embedding correlator from\nwhich the time-dependent current can be calculated using the Meir-Wingreen\nformula. We show how to efficiently implement our approach through a simple\ngrafting into recently proposed time-linear Green's function methods for closed\nsystems. Electron-electron and electron-phonon interactions can be treated on\nequal footing while preserving all fundametal conservation laws.",
        "positive": "Vortex Clusters in Quantum Dots: We study electronic structures of two-dimensional quantum dots in strong\nmagnetic fields using mean-field density-functional theory and exact\ndiagonalization. Our numerically accurate mean-field solutions show a\nreconstruction of the uniform-density electron droplet when the magnetic field\nflux quanta enter one by one the dot in stronger fields. These quanta\ncorrespond to repelling vortices forming polygonal clusters inside the dot. We\nfind similar structures in the exact treatment of the problem using a new type\nof operator for the analysis. We discuss important differences and limitations\nof the methods used."
    },
    {
        "anchor": "Energy Levels of Quantum Ring in ABA-Stacked Trilayer Graphene: We present the solutions of the energy spectrum of charge carriers confined\nin quantum ring in ABA-stacked trilayer graphene subjected to a perpendicular\nmagnetic field. The calculations were performed in the context of the continuum\nmodel by solving the Dirac equation for a zero width ring geometry, i.e.\nfreezing out the carrier radial motion. We show that the obtained energy\nspectrum exhibits different symmetries with respect to the magnetic field and\nother parameters. The application of a potential shift the energy spectrum\nvertically while the application of a magnetic field breaks all symmetries. We\ncompare our results with those of of the ideal quantum ring in monolayer and\nbilayer graphene.",
        "positive": "Spectroscopic Evidence of the Aharonov-Casher effect in a Cooper Pair\n  Box: We have observed the effect of the Aharonov-Casher (AC) interference on the\nspectrum of a superconducting system containing a symmetric Cooper pair box\n(CPB) and a large inductance. By varying the charge $n_{g}$ induced on the CPB\nisland, we observed oscillations of the device spectrum with the period $\\Delta\nn_{g}=2e$. These oscillations are attributed to the charge-controlled AC\ninterference between the fluxon tunneling processes in the CPB Josephson\njunctions. Total suppression of the tunneling (complete destructive\ninterference) has been observed for the charge $n_{g}=e(2n+1)$. The CPB in this\nregime represents the $4\\pi$-periodic Josephson element, which can be used for\nthe development of the parity-protected superconducting qubits."
    },
    {
        "anchor": "Frequency dependent dielectric response of ferroelectric-dielectric\n  junction with negative electric capacitance: We calculated the frequency dependent dielectric response (electric\nsusceptibility) of layered ferroelectric-dielectric junction, biased by the\ntime-dependent harmonic voltage with single frequency $\\omega$. Working point\nis stabilized, by the charge boundary condition between the layers, in the\nregion with negative electric capacitance. The static susceptibility $\\chi_0$\nis negative and relative dielectric constant $\\epsilon_r$ smaller than one,\nclearly indicating the opposite direction of electric field and polarization in\nthe ferroelectric layer due to the negative electric capacitance. At finite\nfrequencies this sign is preserved in real part of susceptibility which gains\nthe frequency dependence. Also, frequency dependent imaginary part arises due\nto the phase shift between electric field and polarization. The type of that\nfrequency dependence in linear regime is so-called relaxation (Debye) response,\ni.e. $\\chi'(\\omega)=\\chi_0/(1+(\\tau \\omega)^2)$ and $\\chi\"(\\omega)=\\chi_0\\tau\n\\omega/(1+(\\tau \\omega)^2)$, where $\\tau$ is polarization switching time\ncharacteristic to ferroelectric material. In particular, we modeled the\njunction of ferroelectric BaTiO$_3$ and dielectric Al$_2$O$_3$, taking the\nexperimental values of material parameters, and addressed the role of\nnonlinearity with respect to result of the linear response theory.",
        "positive": "Tuning superconductivity in twisted bilayer graphene: Materials with flat electronic bands often exhibit exotic quantum phenomena\nowing to strong correlations. Remarkably, an isolated low-energy flat band can\nbe induced in bilayer graphene by simply rotating the layers to 1.1$^{\\circ}$,\nresulting in the appearance of gate-tunable superconducting and correlated\ninsulating phases. Here, we demonstrate that in addition to the twist angle,\nthe interlayer coupling can also be modified to precisely tune these phases. We\nestablish the capability to induce superconductivity at a twist angle larger\nthan 1.1$^{\\circ}$ $-$ in which correlated phases are otherwise absent $-$ by\nvarying the interlayer spacing with hydrostatic pressure. Realizing devices\nwith low disorder additionally reveals new details about the superconducting\nphase diagram and its relationship to the nearby insulator. Our results\ndemonstrate twisted bilayer graphene to be a uniquely tunable platform for\nexploring novel correlated states."
    },
    {
        "anchor": "Design of Porous Metal-Organic Frameworks for Adsorption Driven Thermal\n  Batteries: Thermal batteries based on a reversible adsorption-desorption of a working\nfluid rather than the conventional vapor compression is a promising alternative\nto exploit waste thermal energy for heat reallocation. In this context, there\nis an increasing interest to find novel porous solids able to adsorb a high\nenergy density of working fluid under low relative vapor pressure condition\ncombined with an easy ability of regeneration (desorption) at low temperature,\nwhich are the major requirements for adsorption driven heat pumps and chillers.\nThe porous crystalline hybrid materials named Metal-Organic Frameworks (MOF)\nrepresent a great source of inspiration for sorption based-applications owing\nto their tunable chemical and topological features associated with a large\nvariability of pore sizes. Recently, we have designed a new MOF (named\nMIL-160), isostructural do CAU-10, built from the assembly of corner sharing\naluminum chains octahedra AlO4(OH)2 with the 2,5-furandicarboxylic linker\nsubstituting the pristine organic linker, 1,4-benzenedicarboxylate. This ligand\nreplacement strategy proved to enhance both the hydrophilicity of the MOF and\nits amount of water adsorbed at low p-p0. This designed solid was synthesized\nand its chemical stability/adsorption performances verified. Here, we have\nextended this study by incorporating other polar heterocyclic linkers and a\ncomparative computational study of the water adsorption performances of these\nnovel structures has been performed. To that purpose, the cell and geometry\noptimizations of all hypothetical frameworks were first performed at the\ndensity functional theory level and their water adsorption isotherms were\nfurther predicted by using force-field based Grand-Canonical Monte Carlo\nsimulations. This study reveals the ease tunable water affinity of MOF for the\ndesired application.",
        "positive": "Bond-disordered Anderson model on a two dimensional square lattice -\n  chiral symmetry and restoration of one-parameter scaling: Bond-disordered Anderson model in two dimensions on a square lattice is\nstudied numerically near the band center by calculating density of states\n(DoS), multifractal properties of eigenstates and the localization length. DoS\ndivergence at the band center is studied and compared with Gade's result [Nucl.\nPhys. B 398, 499 (1993)] and the powerlaw. Although Gade's form describes\naccurately DoS of finite size systems near the band-center, it fails to\ndescribe the calculated part of DoS of the infinite system, and a new\nexpression is proposed. Study of the level spacing distributions reveals that\nthe state closest to the band center and the next one have different level\nspacing distribution than the pairs of states away from the band center.\nMultifractal properties of finite systems furthermore show that scaling of\neigenstates changes discontinuously near the band center. This unusual behavior\nsuggests the existence of a new divergent length scale, whose existence is\nexplained as the finite size manifestation of the band center critical point of\nthe infinite system, and the critical exponent of the correlation length is\ncalculated by a finite size scaling. Furthermore, study of scaling of Lyapunov\nexponents of transfer matrices of long stripes indicates that for a long stripe\nof any width there is an energy region around band center within which the\nLyapunov exponents cannot be described by one-parameter scaling. This region,\nhowever, vanishes in the limit of the infinite square lattice when\none-parameter scaling is restored, and the scaling exponent calculated, in\nagreement with the result of the finite size scaling analysis."
    },
    {
        "anchor": "Boron Nitride Nanotubes as Templates for Half-Metal Nanowires: We investigate by means of DFT/GGA+U calculations the electronic and\nstructural properties of magnetic nanotubes composed of an iron oxide monolayer\nand (n,0) Boron Nitride (BN) nanotubes, with n ranging from 6 up to 14. The\nformation energy per FeO molecule of FeO covered tubes is smaller than the\nformation energy of small FeO nanoparticles which suggest that the FeO\nmolecules may cover the BN nanotubes rather than to aggregate to form the FeO\nbulk. We propose a continuous model for the FeO covered BN nanotubes formation\nenergy which predicts that BN tubes with diameter of roughly 13 \\AA are the\nmost stable. Unlike carbon nanotubes, the band structure of FeO covered BN\nnanotubes can not be obtained by slicing the band structure of a FeO layer, the\ncurvature and the interaction with the BN tube is determinant for the\nelectronic behavior of FeO covered tubes. As a result the tubes are\nsemiconductors, intrinsic half-metals or semi-half-metals that can become\nhalf-metals charged with either electrons and holes. Such a result may be\nimportant in the spintronics context.",
        "positive": "Zero bias conductance peak in InAs nanowire coupled to superconducting\n  electrodes: We report the occurrence of the zero-bias conductance peak (ZBCP) in an InAs\nnanowire coupled to PbIn superconductors with varying temperature, bias\nvoltage, and magnetic field. The ZBCP is suppressed with increasing temperature\nand bias voltage above the Thouless energy of the nanowire. Applying a magnetic\nfield also diminishes the ZBCP when the resultant magnetic flux reaches the\nmagnetic flux quantum h/2e. Our observations are consistent with theoretical\nexpectations of reflectionless tunneling, in which the phase coherence between\nan electron and its Andreev-reflected hole induces the ZBCP as long as\ntime-reversal symmetry is preserved."
    },
    {
        "anchor": "Top-gated graphene field-effect-transistors formed by decomposition of\n  SiC: Top-gated, few-layer graphene field-effect transistors (FETs) fabricated on\nthermally-decomposed semi-insulating 4H-SiC substrates are demonstrated.\nPhysical vapor deposited SiO2 is used as the gate dielectric. A two-dimensional\nhexagonal arrangement of carbon atoms with the correct lattice vectors,\nobserved by high-resolution scanning tunneling microscopy, confirms the\nformation of multiple graphene layers on top of the SiC substrates. The\nobservation of n-type and p-type transition further verifies Dirac Fermions\nunique transport properties in graphene layers. The measured electron and hole\nmobility on these fabricated graphene FETs are as high as 5400 cm2/Vs and 4400\ncm2/Vs respectively, which are much larger than the corresponding values from\nconventional SiC or silicon.",
        "positive": "Imaging field-tuned quantum Hall broken-symmetry orders and quantum Hall\n  conducting channel in charge-neutral graphene WSe2 heterostructure: The zeroth Landau level (0LL) in graphene has emerged as a flat-band platform\nin which distinct many-body phases can be explored with unprecedented control\nby simply tuning the strength and/or direction of magnetic fields1-22. A rich\nset of quantum Hall ferromagnetic (QHFM) phases with different lattice-scale\nsymmetry-breaking orders are predicted to be realized in high magnetic fields\nwhen the 0LL in graphene is half filled1-8,13-16. Here we report a field-tuned\ncontinuous quantum phase transition of different valley orderings in QHFM of\ncharge-neutral graphene on insulating tungsten diselenide (WSe2). The phase\ntransition is clearly revealed by anomalous field-dependent energy gap in the\nhalf-filled 0LL. Via atomic resolution imaging of electronic wavefunctions\nduring the phase transition, we observe microscopic signatures of field-tuned\ncontinuous-varied valley polarization and valley inversion, which are\nunexpected and beyond current theory predictions. Moreover, the topological\nquantum Hall conducting channel of the graphene is directly imaged when the\nsubstrate (WSe2) introduces band bending of the 0LL."
    },
    {
        "anchor": "Microscopic understanding of ultrafast charge transfer in van-der-Waals\n  heterostructures: Van-der-Waals heterostructures show many intriguing phenomena including\nultrafast charge separation following strong excitonic absorption in the\nvisible spectral range. However, despite the enormous potential for future\napplications in the field of optoelectronics, the underlying microscopic\nmechanism remains controversial. Here we use time- and angle-resolved\nphotoemission spectroscopy combined with microscopic many-particle theory to\nreveal the relevant microscopic charge transfer channels in epitaxial\nWS$_2$/graphene heterostructures. We find that the timescale for efficient\nultrafast charge separation in the material is determined by direct tunneling\nat those points in the Brillouin zone where WS$_2$ and graphene bands cross,\nwhile the lifetime of the charge separated transient state is set by\ndefect-assisted tunneling through localized sulphur vacanices. The subtle\ninterplay of intrinsic and defect-related charge transfer channels revealed in\nthe present work can be exploited for the design of highly efficient light\nharvesting and detecting devices.",
        "positive": "Microwave-induced suppression of dissipative conductivity and its\n  Shubnikov -- de Haas oscillations in two-dimensional electron systems: Effect\n  of dynamic electron localization: We present a model for microwave photoconductivity in two-dimensional\nelectron systems (2DESs) in a magnetic field at the microwave frequencies lower\nthat the electron cyclotron frequency when the intra-Landau level (LL)\ntransitions dominate. Using this model, we explain the effect of decrease in\nthe 2DES dissipative conductivity (and resistivity) and smearing of its\nShubnikov -- de Haas oscillations by microwave radiation observed recently\n\\cite{1,2}. The model invokes the concept of suppression of elastic impurity\nscattering of electrons by the microwave electric field. We calculated the\ndependence of the 2DES conductivity associated with intra-LL transitions as a\nfunction of the radiation and cyclotron frequencies and microwave power. The\nobtained dependences are consistent with the results of recent experimental\nobservations \\cite{1,2}."
    },
    {
        "anchor": "Photo-Induced Topological Phase Transition and a Single Dirac-Cone State\n  in Silicene: Silicene (a monolayer of silicon atoms) is a quantum spin Hall insulator\n(QSHI), which undergoes a topological phase transition to a band insulator\nunder external electric field $E_{z}$. We investigate a photo-induced\ntopological phase transition by irradiating circular polarized light at fixed\n$E_{z}$. The band structure and also the topological property are modified by\nphoton dressing. By increasing the intensity of light at $E_{z}=0 $, a\nphoto-induced quantum Hall insulator (P-QHI) is realized, where the quantum\nHall effect occurs without magnetic field. Its edge modes are anisotropic\nchiral, in which the velocities of up and down spins are different. There\nappears a spin polarized metal characterized by topological flat bands at the\ncritical point between the QSHI and P-QHI. At $E_{z}>E_{\\text{cr}}$ with a\ncertain critical field $E_{\\text{cr}}$, a photo-induced spin-polarized quantum\nHall insulator emerge. This is a new state of matter, possessing one Chern\nnumber and one half spin-Chern numbers. The edge mode supports a perfectly\nspin-polarized current, which are different from the chiral or helical edge\nmodes. We newly discovered a single Dirac-cone state along a phase boundary. A\ndistinctive hallmark of the state is that one of the two Dirac valleys is\nclosed with a linear dispersion and the other open with a parabolic dispersion.",
        "positive": "Long ranged singlet proximity effect in ferromagnetic nanowires: Recently a long ranged superconductor/ferromagnet (S/F) proximity effect has\nbeen reported in Co crystalline nanowires [1, Nature, 6 389 (2010)]. Since the\nauthors of [1] take care to avoid the existence of magnetic domains, the\ntriplet character of the long ranged proximity effect is improbable. Here we\ndemonstrate that in the one-dimensional ballistic regime the standard singlet\nS/F proximity effect becomes long ranged. We provide an exact solution for the\ndecay of the superconducting correlations near critical temperature ($T_{c}$)\nand for arbitrary impurities concentration. In particular we find a specific\nregime, between the diffusive and ballistic ones, where the decay length is\nsimply the electronic mean-free path. Finally possible experiments which could\npermit to elucidate the nature of the observed long ranged proximity effect in\nCo nanowires are discussed."
    },
    {
        "anchor": "Spin accumulation without spin current: The spin Hall (SH) effect is a phenomenon in which the spin current flows\nperpendicular to an applied electric field and causes the spin accumulation at\nthe boundaries. However, in the presence of spin-orbit couplings, the spin\ncurrent is not well defined. Here, we calculate the spin response to an\nelectric-field gradient, which naturally appears at the boundaries. We derive a\ngeneric formula using the Bloch wave functions and the phenomenological\nrelaxation time. We also calculate the response for the uniform Rashba model\nwith $\\delta$-function nonmagnetic disorder within the first-order Born\napproximation and corresponding vertex corrections. We find the nonzero spin\naccumulation, although the SH conductivity exactly vanishes.",
        "positive": "Orbital and spin relaxation in single and coupled quantum dots: Phonon-induced orbital and spin relaxation rates of single electron states in\nlateral single and double quantum dots are obtained numerically for realistic\nmaterials parameters. The rates are calculated as a function of magnetic field\nand interdot coupling, at various field and quantum dot orientations. It is\nfound that orbital relaxation is due to deformation potential phonons at low\nmagnetic fields, while piezoelectric phonons dominate the relaxation at high\nfields. Spin relaxation, which is dominated by piezoelectric phonons, in single\nquantum dots is highly anisotropic due to the interplay of the Bychkov-Rashba\nand Dresselhaus spin-orbit couplings. Orbital relaxation in double dots varies\nstrongly with the interdot coupling due to the cyclotron effects on the\ntunneling energy. Spin relaxation in double dots has an additional anisotropy\ndue to anisotropic spin hot spots which otherwise cause giant enhancement of\nthe rate at useful magnetic fields and interdot couplings. Conditions for the\nabsence of the spin hot spots in in-plane magnetic fields (easy passages) and\nperpendicular magnetic fields (weak passages) are formulated analytically for\ndifferent growth directions of the underlying heterostructure. It is shown that\neasy passages disappear (spin hot spots reappear) if the double dot system\nloses symmetry by an xy-like perturbation."
    },
    {
        "anchor": "Microscopy of hydrogen and hydrogen-vacancy defect structures on\n  graphene devices: We have used scanning tunneling microscopy (STM) to investigate two types of\nhydrogen defect structures on monolayer graphene supported by hexagonal boron\nnitride (h-BN) in a gated field-effect transistor configuration. The first\nH-defect type is created by bombarding graphene with 1-keV ionized hydrogen and\nis identified as two hydrogen atoms bonded to a graphene vacancy via comparison\nof experimental data to first-principles calculations. The second type of H\ndefect is identified as dimerized hydrogen and is created by depositing atomic\nhydrogen having only thermal energy onto a graphene surface. Scanning tunneling\nspectroscopy (STS) measurements reveal that hydrogen dimers formed in this way\nopen a new elastic channel in the tunneling conductance between an STM tip and\ngraphene.",
        "positive": "Plasmonics of magnetic and topological graphene-based nanostructures: Graphene is a unique material to study fundamental limits of plasmonics.\nApart from the ultimate single-layer thickness, its carrier concentration can\nbe tuned by chemical doping or applying an electric field. In this manner the\nelectrodynamic properties of graphene can be varied from highly conductive to\ndielectric. Graphene supports strongly confined, propagating surface\nplasmon-polaritons (SPPs) in a broad spectral range from terahertz to\nmid-infrared frequencies. It also possesses a strong magneto-optical response\nand thus provides complimentary architectures to conventional\nmagneto-plasmonics based on magneto-optically active metals or dielectrics.\nDespite of a large number of review articles devoted to plasmonic properties\nand applications of graphene, little is known about graphene magneto-plasmonics\nand topological effects in graphene-based nanostructures, which represent the\nmain subject of this review. We discuss several strategies to enhance plasmonic\neffects in topologically distinct closed surface landscapes, i.e. graphene\nnanotubes, cylindric nanocavities and toroidal nanostructures. A novel\nphenomenon of the strongly asymmetric SPP propagation on chiral meta-structures\nand fundamental relations between structural and plasmonic topological indices\nare reviewed."
    },
    {
        "anchor": "Quantum Hall effect at low magnetic fields: The temperature and scale dependence of resistivities in the standard scaling\ntheory of the integer quantum Hall effect is discussed. It is shown that recent\nexperiments, claiming to observe a discrepancy with the global phase diagram of\nthe quantum Hall effect, are in fact in agreement with the standard theory. The\napparent low-field transition observed in the experiments is identified as a\ncrossover due to weak localization and a strong reduction of the conductivity\nwhen Landau quantization becomes dominant.",
        "positive": "Towards superfluidity of dipolar excitons in a TMDC double layer: We study formation and superfluidity of dipolar excitons in double layer\nheterostructures formed by two transition metal dichalcogenide (TMDC)\natomically thin layers. Considering screening effects for an electron-hole\ninteraction via the harmonic oscillator approximation for the Keldysh\npotential, the analytical expressions for the exciton energy spectrum and the\nmean field critical temperature $T_{c}$ for the superfluidity are obtained. It\nis shown that binding energies of A excitons are larger than for B excitons.\nThe mean field critical temperature for a two-component dilute exciton system\nin a TMDC double layer is analyzed and shown that latter is an increasing\nfunction of the factor $Q$, determined by the effective masses of A and B\nexcitons and their reduced mass. Comparison of the calculations for $T_{c}$\nperformed by employing the Coulomb and Keldysh interactions demonstrates the\nimportance of screening effects in TMDC."
    },
    {
        "anchor": "Magnetotransport in Aharonov Bohm interferometers: Exact numerical\n  simulations: The linear conductance of a two-terminal Aharonov-Bohm interferometer is an\neven function of the applied magnetic flux, as dictated by the Onsager-Casimir\nsymmetry. Away from linear response this symmetry may be broken when many-body\ninteractions are in effect. Using a numerically-exact simulation tool, we study\nthe dynamics and the steady-state behavior of the out-of-equilibrium double-dot\nAharonov Bohm interferometer, while considering different types of\ninteractions: Model I includes a closed interferometer with an inter-dot\nelectron-electron repulsion energy. In model II the interferometer is\ninteracting with a dissipative environment, possibly driven away from\nequilibrium. In both cases we show that depending on the (horizontal, vertical)\nmirror symmetries of the setup, nonlinear transport coefficients obey certain\nmagnetosymmetries. We compare numerically exact simulations to phenomenological\napproaches: The behavior of model I is compared to self-consistent mean-field\ncalculations. Model II, allowing heat dissipation to a thermal bath, is\nmimicked by an Aharonov Bohm junction with a voltage probe. In both cases we\nfind that phenomenological treatments capture the relevant transport\nsymmetries, yet significant deviations in magnitude may show up.",
        "positive": "Reply to the Comment on \"Negative Landau damping in bilayer graphene\": Here we address the concerns of Svintsov and Ryzhii [arXiv:1812.03764] on our\narticle on negative Landau damping in graphene [Phys. Rev. Lett. 119, 133901\n(2017)]. We prove that due to the differences between the kinetic and canonical\nmomenta, the conductivity of drift-current biased graphene is ruled by a\nGalilean transformation when the electron-electron interactions predominate and\nforce the electron gas to move with constant velocity, similar to a moving\nmedium. Furthermore, it is shown that the nonlocal effects in graphene neither\npreclude a negative Landau damping nor the emergence of instabilities in\ngraphene platforms."
    },
    {
        "anchor": "Low-temperature quantum transport in CVD-grown single crystal graphene: Chemical vapor deposition (CVD) has been proposed for large-scale graphene\nsynthesis for practical applications. However, the inferior electronic\nproperties of CVD graphene are one of the key problems to be solved. In this\nstudy, we present a detailed study on the electronic properties of high-quality\nsingle crystal monolayer graphene. The graphene is grown by CVD on copper using\na cold-wall reactor and then transferred to Si/SiO2. Our low-temperature\nmagneto-transport data demonstrate that the characteristics of the measured\nsingle-crystal CVD graphene samples are superior to those of polycrystalline\ngraphene and have a quality which is comparable to that of exfoliated graphene\non Si/SiO2. The Dirac point in our best samples is located at back-gate\nvoltages of less than 10V, and their mobility can reach 11000 cm2/Vs. More than\n12 flat and discernible half-integer quantum Hall plateaus have been observed\nin high magnetic field on both the electron and hole side of the Dirac point.\nAt low magnetic field, the magnetoresistance shows a clear weak localization\npeak. Using the theory of McCann et al., we find that the inelastic scattering\nlength is larger than 1 {\\mu}m in these samples even at the charge neutrality\npoint.",
        "positive": "High-Conductive Organometallic Molecular Wires with Delocalized Electron\n  Systems Strongly Coupled to Metal Electrodes: Besides active, functional molecular building blocks such as diodes or\nswitches, passive components as, e.g., molecular wires, are required to realize\nmolecular-scale electronics. Incorporating metal centers in the molecular\nbackbone enables the molecular energy levels to be tuned in respect to the\nFermi energy of the electrodes. Furthermore, by using more than one metal\ncenter and sp-bridging ligands, a strongly delocalized electron system is\nformed between these metallic \"dopants\", facilitating transport along the\nmolecular backbone. Here, we study the influence of molecule--metal coupling on\ncharge transport of dinuclear X(PP)$_2$FeC$_4$Fe(PP)$_2$X molecular wires (PP =\nEt$_2$PCH$_2$CH$_2$PEt$_2$); X = CN (1), NCS (2), NCSe (3), C$_4$SnMe$_3$ (4)\nand C$_2$SnMe$_3$ (5)) under ultra-high vacuum and variable temperature\nconditions. In contrast to 1 which showed unstable junctions at very low\nconductance ($8.1\\cdot10^{-7}$ G$_0$), 4 formed a Au-C$_4$FeC$_4$FeC$_4$-Au\njunction 4' after SnMe$_3$ extrusion which revealed a conductance of\n$8.9\\cdot10^{-3}$ G$_0$, three orders of magnitude higher than for 2\n($7.9\\cdot10^{-6}$ G$_0$) and two orders of magnitude higher than for 3\n($3.8\\cdot10^{-4}$ G$_0$). Density functional theory (DFT) confirmed the\nexperimental trend in the conductance for the various anchoring motifs. The\nstrong hybridization of molecular and metal states found in the C--Au coupling\ncase enables the delocalized electronic system of the organometallic Fe$_2$\nbackbone to be extended over the molecule-metal interfaces to the metal\nelectrodes to establish high-conductive molecular wires."
    },
    {
        "anchor": "Gating a single-molecule transistor with individual atoms: Transistors, regardless of their size, rely on electrical gates to control\nthe conductance between source and drain contacts. In atomic-scale transistors,\nthis conductance is exquisitely sensitive to single electrons hopping via\nindividual orbitals. Single-electron transport in molecular transistors has\nbeen previously studied using top-down approaches to gating, such as\nlithography and break junctions. But atomically precise control of the gate -\nwhich is crucial to transistor action at the smallest size scales - is not\npossible with these approaches. Here, we used individual charged atoms,\nmanipulated by a scanning tunnelling microscope, to create the electrical gates\nfor a single-molecule transistor. This degree of control allowed us to tune the\nmolecule into the regime of sequential single-electron tunnelling, albeit with\na conductance gap more than one order of magnitude larger than observed\npreviously. This unexpected behaviour arises from the existence of two\ndifferent orientational conformations of the molecule, depending on its charge\nstate. Our results show that strong coupling between these charge and\nconformational degrees of freedom leads to new behaviour beyond the established\npicture of single-electron transport in atomic-scale transistors.",
        "positive": "Rippling of two-dimensional materials by line defects: Two-dimensional materials and their mechanical properties are known to be\nprofoundly affected by rippling deformations. However, although ripples are\nfairly well understood, less is known about their origin and controlled\nmodification. Here, motivated by recent reports of laser-controlled creation of\nline defects in graphene, we investigate how line defects could be used to\ncontrol rippling in graphene and other two-dimensional materials. By sequential\nmulti-scale coupling of density-functional tight-binding and continuum\nelasticity simulations, we quantify the amount of rippling when the number and\nthe cumulative length of the line defects increase. Simulations show that\nelastic sheets with networks of line defects create rippling that induces\nconsiderable out-of-plane rigidification and in-plane softening with non-linear\nelastic behavior. We hope that these insights help to guide experimental\nattempts to modify the mechanical properties of graphene and other\ntwo-dimensional materials."
    },
    {
        "anchor": "Electron spin orientation under in-plane optical excitation in GaAs\n  quantum wells: We study the optical orientation of electron spins in GaAs/AlGaAs quantum\nwells for excitation in the growth direction and for in-plane excitation. Time-\nand polarization-resolved photoluminescence excitation measurements show, for\nresonant excitation of the heavy-hole conduction band transition, a negligible\ndegree of electron spin polarization for in-plane excitation and nearly 100%\nfor excitation in the growth direction. For resonant excitation of the\nlight-hole conduction band transition, the excited electron spin polarization\nhas the same (opposite) direction for in-plane excitation (in the growth\ndirection) as for excitation into the continuum. The experimental results are\nwell explained by an accurate multiband theory of excitonic absorption taking\nfully into account electron-hole Coulomb correlations and heavy-hole light-hole\ncoupling.",
        "positive": "Thermoelectric effect in molecular junctions: A tool for revealing\n  transport mechanisms: We investigate the thermopower of a metal-molecule-metal junction taking into\naccount thermal effects on the junction. Based on analytical expressions and\nnumerical simulations we show that the thermoelectric potential reveals\nvaluable information on the mechanisms controlling the electron transfer\nprocess, including coherent transmission and thermalized hopping. We also show\nthat at high temperatures the position of the Fermi energy relative to the\nmolecular states can be easily deduced from the thermoelectric potential.\nStandard current-voltage measurements are insensitive to this information."
    },
    {
        "anchor": "Optical absorption tensors based on C$_{70}$ trimers and polymers: The optical absorption spectrum of $C_{60}$-dimers and polymers was\ninvestigated by Kikuo et al. in 1996\\cite{harigaya1996charge}. As a compliment\nto these earlier studies, the optical absorption spectrum of the $C_{70}$\nfullerene has been investigated in the present study. The main purpose was then\nto compare the absorption spectrum of the $C_{70}$-dimers and trimers and, more\nspecifically, to clarify the effect of these molecular structures on the\nabsorption spectrum. What is most important and decisive is then the value of\nthe conjugation parameter of these $C_{70}$-based molecules. In the present\nstudy, a tight-binding model was used in calculating the optical absorption\nspectra of both $C_{70}$ dimers and polymers, as well as $C_{70}$ trimers and\npolymers. The change in conjugation parameter for each of these species was\nfound to cause variations in the corresponding optical absorption spectrum. It\nwas found that the absorption tensor of the $C_{70}$ trimer and the polymer\nwas, depending on the value of the conjugation parameters $b=0.5$ and $b=0.8$.\nThe situation was almost the same for the conjugation parameters $b=0.1$ and\n$b=0.2$. In addition, the value of the band gap was also different depending on\nthe different conjugation parameters, with a reduced value for the larger\nvalues of this parameter. As a conclusion, smaller values of the conjugation\nparameter were not found to have a large effect on the absorption spectrum of\nthe $C_{70}$-dimers and trimers, or in other words, the effect was hardly\nvisible. On the contrary, the larger values caused a drastic change in the\noptical absorption spectrum of the $C_{70}$-dimers and trimers.",
        "positive": "Coherent spin-qubit photon coupling: Electron spins hold great promise for quantum computation due to their long\ncoherence times. An approach to realize interactions between distant\nspin-qubits is to use photons as carriers of quantum information. We\ndemonstrate strong coupling between single microwave photons in a NbTiN high\nimpedance cavity and a three-electron spin-qubit in a GaAs triple quantum dot.\nWe resolve the vacuum Rabi mode splitting with a coupling strength of\n$g/2\\pi\\simeq31$ MHz and a qubit decoherence of $\\gamma_2/2\\pi\\simeq 20$ MHz.\nWe can tune the decoherence electrostatically and obtain a minimal\n$\\gamma_2/2\\pi\\simeq 10$ MHz for $g/2\\pi\\simeq 23$ MHz. The dependence of the\nqubit-photon coupling strength on the tunable electric dipole moment of the\nqubit is measured directly using the ac Stark effect. Our demonstration of\nstrong spin-photon interaction is an important step towards coherent\nlong-distance coupling of spin-qubits."
    },
    {
        "anchor": "Current-Induced Dynamics and Chaos of Antiferromagnetic Bimerons: A magnetic bimeron is a topologically non-trivial spin texture carrying an\ninteger topological charge, which can be regarded as the counterpart of\nskyrmion in easy-plane magnets. The controllable creation and manipulation of\nbimerons are crucial for practical applications based on topological spin\ntextures. Here, we analytically and numerically study the dynamics of an\nantiferromagnetic bimeron driven by a spin current. Numerical simulations\ndemonstrate that the spin current can create an isolated bimeron in the\nantiferromagnetic thin film via the damping-like spin torque. The spin current\ncan also effectively drive the antiferromagnetic bimeron without a transverse\ndrift. The steady motion of an antiferromagnetic bimeron is analytically\nderived and is in good agreement with the simulation results. Also, we find\nthat the alternating-current-induced motion of the antiferromagnetic bimeron\ncan be described by the Duffing equation due to the presence of the nonlinear\nboundary-induced force. The associated chaotic behavior of the bimeron is\nanalyzed in terms of the Lyapunov exponents. Our results demonstrate the\ninertial dynamics of an antiferromagnetic bimeron, and may provide useful\nguidelines for building future bimeron-based spintronic devices.",
        "positive": "Point-contact electron-phonon interaction function in tantalum: Tantalum is studied by the method of point-contact (PC) spectroscopy: the\nparameter ${{\\lambda }_{pc}}$ and the absolute intensity of the PC EPI function\nare determined, and the form of the EPI function is determined more accurately.\nBoth homocontacts $Ta-Ta$ and heterocontacts $Ta-Cu$ and $Ta-Au$ were studied.\nIt was found that the contributions of copper and gold to the spectrum of the\nheterocontact are not noticeable, though the forms of the PC spectra of $Ta$ in\nhomo- and heterocontacts are different. The intensities of the spectra of\n$Ta-Ta$ homocontacts and $Ta-Cu$ heterocontacts turned out to be close to one\nanother. Simple expressions, enabling numerical calculations of the PC\ncharacteristics for geometrically symmetric heterocontacts in the approximation\nof a spherical Fermi surface, are derived, based on the theory. It is shown\nthat the use of the free-electron approximation in the numerical estimates\nleads to an error. It is proposed that the effective mass approximation be used\nfor such estimates."
    },
    {
        "anchor": "Manipulation of single electron spin in a GaAs quantum dot through the\n  application of geometric phases: The Feynman disentangling technique: The spin of a single electron in an electrically defined quantum dot in a\n2DEG can be manipulated by moving the quantum dot adiabatically in a closed\nloop in the 2D plane under the influence of applied gate potentials. In this\npaper we present analytical expressions and numerical simulations for the\nspin-flip probabilities during the adiabatic evolution in the presence of the\nRashba and Dresselhaus linear spin-orbit interactions. We use the Feynman\ndisentanglement technique to determine the non-Abelian Berry phase and we find\nexact analytical expressions for three special cases: (i) the pure Rashba\nspin-orbit coupling, (ii) the pure Dresselhause linear spin-orbit coupling, and\n(iii) the mixture of the Rashba and Dresselhaus spin-orbit couplings with equal\nstrength. For a mixture of the Rashba and Dresselhaus spin-orbit couplings with\nunequal strengths, we obtain simulation results by solving numerically the\nRiccati equation originating from the disentangling procedure. We find that the\nspin-flip probability in the presence of the mixed spin-orbit couplings is\ngenerally larger than those for the pure Rashba case and for the pure\nDresselhaus case, and that the complete spin-flip takes place only when the\nRashba and Dresselhaus spin-orbit couplings are mixed symmetrically.",
        "positive": "Non-equilibrium Luttinger liquid: Zero-bias anomaly and dephasing: A one-dimensional system of interacting electrons out of equilibrium is\nstudied in the framework of the Luttinger liquid model. We analyze several\nsetups and develop a theory of tunneling into such systems. A remarkable\nproperty of the problem is the absence of relaxation in energy distribution\nfunctions of left- and right-movers, yet the presence of the finite dephasing\nrate due to electron-electron scattering, which smears zero-bias-anomaly\nsingularities in the tunneling density of states."
    },
    {
        "anchor": "Mass Renormalization in Transition Metal Dichalcogenides: It is shown that the three-fold rotational symmetry in transition metal\ndichalcogenides leads to a Coulomb induced renormalization of the effective\nelectron and hole masses near the $K$-points of the Brillouin zone. The\nmagnitude of the renormalization depends on the dielectric configuration. The\neffective exciton mass $m=0.4 m_0$ of a freely suspended MoS$_2$ monolayer\nchanges to $m= 0.35 m_0$ with hBN encapsulation. The mass renormalization\nincreases the excitonic binding energy and reduces the exciton diamagnetic\nshift and cyclotron frequency. Detailed comparisons with high field\nmeasurements of the excitonic diamagnetic shift show excellent agreement.",
        "positive": "Spin Transport at Interfaces with Spin-Orbit Coupling: Formalism: We generalize magnetoelectronic circuit theory to account for spin transfer\nto and from the atomic lattice via interfacial spin-orbit coupling. This\nenables a proper treatment of spin transport at interfaces between a\nferromagnet and a heavy-metal non-magnet. This generalized approach describes\nspin transport in terms of drops in spin and charge accumulations across the\ninterface (as in the standard approach), but additionally includes the\nresponses from in-plane electric fields and offsets in spin accumulations. A\nkey finding is that in-plane electric fields give rise to spin accumulations\nand spin currents that can be polarized in any direction, generalizing the\nRashba-Edelstein and spin Hall effects. The spin accumulations exert torques on\nthe magnetization at the interface when they are misaligned from the\nmagnetization. The additional out-of-plane spin currents exert torques via the\nspin-transfer mechanism on the ferromagnetic layer. To account for these\nphenomena we also describe spin torques within the generalized circuit theory.\nThe additional effects included in this generalized circuit theory suggest\nmodifications in the interpretations of experiments involving spin orbit\ntorques, spin pumping, spin memory loss, the Rashba-Edelstein effect, and the\nspin Hall magnetoresistance."
    },
    {
        "anchor": "Dislocation Field Theory in 2D: Application to Graphene: A two-dimensional (2D) dislocation continuum theory is being introduced. The\npresent theory adds elastic rotation, dislocation density, and background\nstress to the classical energy density of elasticity. This theory contains four\nmaterial moduli. Two characteristic length scales are defined in terms of the\nfour material moduli. Non-singular solutions of the stresses and elastic\ndistortions of an edge dislocation are calculated. It has been pointed out that\nthe elastic strain agrees well with experimental data found recently for an\nedge dislocation in graphene.",
        "positive": "Current-Induced Motion of Narrow Domain Walls and Dissipation in\n  Ferromagnetic Metals: Spin transport equations in a non-homogeneous ferromagnet are derived in the\nlimit where the sd exchange coupling between the electrons in the conduction\nband and those in the d band is dominant. It is shown that spin diffusion in\nferromagnets assumes a tensor form. The diagonal terms are renormalized with\nrespect to that in normal metals and enhances the dissipation in the magnetic\nsystem while the off-diagonal terms renormalize the precessional frequency of\nthe conduction electrons and enhances the non-adiabatic spin torque. To\ndemonstrate the new physics in our theory, we show that self-consistent\nsolutions of the spin diffusion equations and the Landau-Lifshitz equations in\nthe presence of a current lead to a an increase in the terminal velocity of a\ndomain wall which becomes strongly dependent on its width. We also provide a\nsimplified equation that predicts damping due to the conduction electrons."
    },
    {
        "anchor": "Comment on \"Negative Landau damping in bilayer graphene\": In [Phys. Rev. Lett. vol. 119, p. 133901 (2017)] it was argued that two\nparallel graphene layers in the presence of electron drift support unstable\nplasmon modes. Here we show that the predicted plasmon instability is an\nartifact of errors upon evaluation of graphene polarizability in the presence\nif electron drift. Crucial role of broken Galilean invariance and spatial\ndispersion of conductivity for suppression of plasmon instabilities is\nhighlighted.",
        "positive": "Integer Quantum Hall Effect in Graphite: We present Hall effect measurements on highly oriented pyrolytic graphite\nthat indicate the occurrence of the integer quantum-Hall-effect. The evidence\nis given by the observation of regular plateau-like structures in the field\ndependence of the transverse conductivity obtained in van der Pauw\nconfiguration. Measurements with the Corbino-disk configuration support this\nresult and indicate that the quasi-linear and non-saturating longitudinal\nmagnetoresistance in graphite is governed by the Hall effect in agreement with\na recent theoretical model for disordered semiconductors."
    },
    {
        "anchor": "Tunnel magnetoresistance and temperature related effects in magnetic\n  tunnel junctions with embedded nanoparticles: Temperature dependence of the tunnel magnetoresistance (TMR) was calculated\nin range of the quantum-ballistic model in the magnetic tunnel junctions (MTJs)\nwith embedded nanoparticles (NPs). The electron tunnel transport through NP was\nsimulated in range of double barrier approach, which was integrated into the\nmodel of the magnetic point-like contact. The resonant TMR conditions and\ntemperature impact were explored in detail. Moreover, the possible reasons of\nthe temperature induced resonant conditions were discussed in the range of the\nlead-tunneling cell-lead model near Kondo temperature. We also found that\nredistribution of the voltage drop becomes crucial in this model. Furthermore,\nthe direct tunneling plays the dominant role and cannot be omitted in the\nquantum systems with the total tunneling thickness up to 5-6 nm. Hence, Coulomb\nblockade model cannot explain Kondo-induced TMR anomalies in nanometer-sized\ntunnel junctions.",
        "positive": "A Novel Non-Volatile Inverter-based CiM: Continuous Sign Weight\n  Transition and Low Power on-Chip Training: In this work, we report a novel design, one-transistor-one-inverter (1T1I),\nto satisfy high speed and low power on-chip training requirements. By\nleveraging doped HfO2 with ferroelectricity, a non-volatile inverter is\nsuccessfully demonstrated, enabling desired continuous weight transition\nbetween negative and positive via the programmable threshold voltage (VTH) of\nferroelectric field-effect transistors (FeFETs). Compared with commonly used\ndesigns with the similar function, 1T1I uniquely achieves pure on-chip-based\nweight transition at an optimized working current without relying on assistance\nfrom off-chip calculation units for signed-weight comparison, facilitating\nhigh-speed training at low power consumption. Further improvements in linearity\nand training speed can be obtained via a two-transistor-one-inverter (2T1I)\ndesign. Overall, focusing on energy and time efficiencies, this work provides a\nvaluable design strategy for future FeFET-based computing-in-memory (CiM)."
    },
    {
        "anchor": "Fluctuation theorem for quantum electron transport in mesoscopic\n  circuits: We study the statistical properties of currents in two particular systems of\ncapacitively coupled parallel transport channels. In the first system, each\ntransport channel contains a single quantum dot in contact with two electron\nreservoirs. The second system we study is constituted of a double quantum dot\ncoupled to two electrodes and probed by a quantum point contact detector.\nThermodynamic forces are applied to each transport channel that generate\nfluctuating stationary currents. The full counting statistics of the currents\nis obtained starting from a microscopic Hamiltonian describing the electron\ndynamics. We verify that the joined probability distribution of the currents in\neach channel satisfies a fluctuation theorem in the long-time limit. The issue\nof single-current fluctuation theorems for the marginal distribution of the\ncurrents in one of the two channels is also investigated. We show that in the\nlimit of large current ratio between both channels, a single-current\nfluctuation theorem is satisfied individually for the slower circuit in\nagreement with experimental observations. This theorem involves an effective\naffinity which depends on the thermodynamic forces applied to both channels and\nthe specific features of the system considered. A detailed study of the\neffective affinity is made for the two aforementioned systems. Besides, we\nintroduce a criteria on the initial condition of the transport channels for the\nobservation of a fluctuation theorem at any time. This criteria is extended to\nthe case of single-current fluctuation theorems. Finally, we perform the\nnonequilibrium thermodynamic analysis of a double quantum dot probed by a\nquantum point contact in the presence of temperature and chemical potential\ndifferences between the electrodes. A thermal machine is studied and shown to\nreach highest efficiencies at maximum power by fine tuning the double quantum\ndot spectrum.",
        "positive": "Deterministic coupling of quantum emitters in WSe$_2$ monolayers to\n  plasmonic nanocavities: We discuss coupling of site-selectively induced quantum emitters in\nexfoliated monolayers of WSe$_2$ to plasmonic nanostructures. Squared and\nrectangular gold nanopillars, which are arranged in pitches of\n\\SI{4}{\\micro\\meter} on the surface, have sizes of tens of nanometers, and act\nas seeds for the formation of quantum emitters in the atomically thin\nmaterials. We observe chraracteristic narrow-band emission signals from the\nmonolayers, which correspond well with the positions of the metallic\nnanopillars with and without thin dielectric coating. Single photon emission\nfrom the emitters is confirmed by autocorrelation measurements, yielding\n$g^{2}(\\tau=0)$ values as low as 0.17. Moreover, we observe a strong\nco-polarization of our single photon emitters with the frequency matched\nplasmonic resonances, indicating deterministic light-matter coupling. Our work\nrepresents a significant step towards the scalable implementation of coupled\nquantum emitter-resonator systems for highly integrated quantum photonic and\nplasmonics applications."
    },
    {
        "anchor": "Majorana fermions at the edge of superconducting islands: We investigate the properties of electron states localized at the edge of a\nsuperconducting island placed on the surface of a topological insulator in a\nmagnetic field. In such systems, Majorana fermions emerge if an odd number of\nvortices (or odd multivortex vorticity) is hosted by the island; otherwise, no\nMajorana states exist. Majorana states emerge in pairs: one state is localized\nnear the vortex core, and another at the island edge. We analyze in detail the\nrobustness of Majorana fermions at the edge of the island threaded by a single\nvortex. If the system parameters are optimized, the energy gap between the\nMajorana fermion and the first excited state at the edge is of the order of the\nsuperconducting gap induced on the surface of the topological insulator. The\nstability of the Majorana fermion state against a variation of the gate voltage\nand its sensitivity to the magnetic field allows one to distinguish\nexperimentally the edge Majorana fermion from conventional Dirac fermions.",
        "positive": "The Structure and Dispersion of Exciton-Trion-Polaritons in\n  Two-Dimensional Materials: Experiments and Theory: The nature of trions and their interaction with light has remained a puzzle.\nThe composition and dispersion of polaritons involving trions provide insights\ninto this puzzle. Trions and excitons in doped two-dimensional (2D) materials\nare not independent excitations but are strongly coupled as a result of Coulomb\ninteractions. When excitons in doped 2D materials are also strongly coupled\nwith light inside an optical waveguide, the resulting polariton states are\ncoherent superpositions of exciton, trion, and photon states. We realize these\nexciton-trion-polaritons by coupling an electron-doped monolayer of\ntwo-dimensional material MoSe2 to the optical mode in a photonic crystal\nwaveguide. Our theoretical model, based on a many-body description of these\npolaritons, reproduces the measured polariton energy band dispersion and Rabi\nsplittings with excellent accuracy. Our work sheds light on the structure of\ntrion states in 2D matrials and also on the indirect mechanism by which they\ninteract with light."
    },
    {
        "anchor": "Spintronics and spincaloritronics in topological insulators: We study spintronics and spincaloritronics in topological insulators. We show\nspintronics effects in 2D topological insulator junctions and 3D topological\ninsulators coupled to ferromagnets. We also investigate spin polarization on\nthe surface of a topological insulator induced by a circularly polarized light\nand refraction at the junction between two topological insulators. As for\nspincaloritronics effects, we show transverse magnetic heat transport and\nthermoelectric transport in topological insulators. Finite-size effect in\ntopological insulators and band structure engineering of interface states of\ntopological insulators are also discussed.",
        "positive": "Partitioning of on-demand electron pairs: We demonstrate the high fidelity splitting of electron pairs emitted on\ndemand from a dynamic quantum dot by an electronic beam splitter. The fidelity\nof pair splitting is inferred from the coincidence of arrival in two detector\npaths probed by a measurement of the partitioning noise. The emission\ncharacteristic of the on-demand electron source is tunable from electrons being\npartitioned equally and independently to electron pairs being split with a\nfidelity of 90%. For low beam splitter transmittance we further find evidence\nof pair bunching violating statistical expectations for independent fermions."
    },
    {
        "anchor": "Cooperative rectification in confined Brownian ratchets: We analyze the rectified motion of a Brownian particle in a confined\nenvironment. We show the emergence of strong cooperativity between the inherent\nrectification of the ratchet mechanism and the entropic bias of the\nfluctuations caused by spatial confinement. Net particle transport may develop\neven in situations where separately the ratchet and the geometric restrictions\ndo not give rise to particle motion. The combined rectification effects can\nlead to bidirectional transport depending on particle size, resulting in a new\nroute for segregation. The reported mechanism can be used to control transport\nin mesostructures and nanodevices in which particles move in a reduced space.",
        "positive": "Spin-Mechanical Inertia in Antiferromagnet: Angular momentum conservation has served as a guiding principle in the\ninterplay between spin dynamics and mechanical rotations. However, in an\nantiferromagnet with vanishing magnetization, new fundamental rules are\nrequired to properly describe spin-mechanical phenomena. Here we show that the\nN\\'eel order dynamics affects the mechanical motion of a rigid body by\nmodifying its inertia tensor in the presence of strong magnetocrystalline\nanisotropy. This effect depends on temperature when magnon excitations are\nconsidered. Such a spin-mechanical inertia can produce measurable consequences\nat small scales."
    },
    {
        "anchor": "Commensuration Effects on Skyrmion Hall Angle and Drag for Manipulation\n  of Skyrmions on Two-Dimensional Periodic Substrates: We examine the dynamics of an individually driven skyrmion moving through a\nbackground lattice of skyrmions coupled to a 2D periodic substrate as we vary\nthe ratio of the number of skyrmions to the number of pinning sites across\ncommensurate and incommensurate conditions. As the skyrmion density increases,\nthe skyrmion Hall angle is nonmonotonic, dropping to low or zero values in\ncommensurate states and rising to an enhanced value in incommensurate states.\nUnder commensuration, the driven skyrmion is channeled by a symmetry direction\nof the pinning array and exhibits an increased velocity. The velocity\nfluctuations have a narrow band signature at fillings where the skyrmion Hall\nangle is zero, while for incommensurate fillings, the skyrmion motion is\ndisordered and the velocity noise is broad band. Under commensurate conditions,\nmulti-step depinning transitions appear and the skyrmion Hall angle is zero at\nlow drives but becomes finite at higher drives, while incommensurate fillings\nhave a single depinning transition. As the Magnus force increases,\ncommensuration velocity peaks cross over to dips, and new directional locking\nangles appear. At large Magnus forces, particularly at commensurate fillings, a\nvelocity boost can occur in which the skyrmion moves faster than the applied\ndrive due to the alignment of the Magnus-induced velocity with the driving\ndirection. Increase the Magnus force can produce regimes of enhanced pinning\nwhen the skyrmion is forced to move along a non-symmetry direction of the\nperiodic pinning array. This is in contrast to systems with random pinning,\nwhere increasing the Magnus force generally reduces the pinning effect. We\ndemonstrate these dynamics for both square and triangular substrates, and map\nout the different regimes as a function of filling fraction, pinning force, and\nthe strength of the Magnus force in a series of dynamic phase diagrams.",
        "positive": "Symmetry classification of energy bands in graphene: We present the results of the first principle calculations of the energy\nbands in graphene and their symmetry classification. The valence bands and four\nlowest conduction bands are classified according to their symmetry at the\npoints $\\Gamma$ and $K$. Merging of the bands is interpreted in the framework\nof the group theory."
    },
    {
        "anchor": "Coulomb and Hard Core Skyrmion Tails: Quantum Hall skyrmions are quantized solitons of a ferromagnetic O(3)\nsigma-model. The reference, classical, solutions depend upon the interaction\nbetween the electrons and exhibit completely different asymptotic profiles for\nthe physical Coulomb interaction than for the model hard core interaction\nfrequently used to generate variational wavefunctions. In this note we show, by\nmeans of numerical calculations on (large) finite size systems at nu=1, that\nthis physically important difference, crucial for a sharp definition of their\nstatistics, persists for the quantized skyrmions at n=1.",
        "positive": "Evidence for incompressible states in a metal graphene tunnel junction\n  in high magnetic field: We present transport measurements of tunnel junctions made between Cu and\ngraphene in a magnetic field. We observe a transition to a Landau level like\nstructure at high fields, as well as a set of sharp features in the tunneling\nspectra that shift with gate and tunnel probe voltage along the lines of\nconstant charge density. We explain the sharp features with the formation of\ndegeneracy split localized Landau levels, and addition of electrons to those\nlevels one by one. A large capacitive coupling to the tunnel probe also\nincreases the gate voltage spacing between the Landau levels."
    },
    {
        "anchor": "Integer quantum Hall effect in a square lattice revisited: We investigate the phenomenon of integer quantum Hall effect in a square\nlattice, subjected to a perpendicular magnetic field, through\nLandauer-B\\\"uttiker formalism within the tight-binding framework. The\noscillating nature of longitudinal resistance and near complete suppression of\nmomentum relaxation processes are examined by studying the flow of charge\ncurrent using Landauer-Keldysh prescription. Our analysis for the lattice model\ncorroborates the finding obtained in the continuum model and provides a simple\nphysical understanding.",
        "positive": "From acene to graphene spectrum of $\u03c0$ electrons with the use of the\n  Green's function: Origin of the spectrum of $\\pi$ electrons that results from coupling of $N$\n$\\cal N$-long acenes via C-C covalent bonding have been traced with the use of\nthe Green function formalism. Exact expressions of acene and graphene Green's\nfunctions, which are useful for analysis of electronic properties of these\nmacromolecules, are obtained and advanced to the form suitable for instructive\napplications."
    },
    {
        "anchor": "Temperature-dependent transport in a sixfold degenerate two-dimensional\n  electron system on a H-Si(111) surface: Low-field magnetotransport measurements on a high mobility (mu=110,000\ncm^2/Vs) two-dimensional (2D) electron system on a H-terminated Si(111) surface\nreveal a sixfold valley degeneracy with a valley splitting <= 0.1 K. The\nzero-field resistivity rho_{xx} displays strong temperature dependence for 0.07\n< T < 25 K as predicted for a system with high degeneracy and large mass. We\npresent a method for using the low-field Hall coefficient to probe intervalley\nmomentum transfer (valley drag). The relaxation rate is consistent with Fermi\nliquid theory, but a small residual drag as T->0 remains unexplained.",
        "positive": "Dynamical decoupling design for identifying weakly coupled nuclear spins\n  in a bath: Identifying weakly coupled nuclear spins around single electron spins is a\nkey step of implementing quantum information processing using coupled\nelectron-nuclei spin systems or sensing like single spin nuclear magnetic\nresonance detection using diamond defect spins. Dynamical decoupling control of\nthe center electron spin with periodic pulse sequences [e.g., the\nCarre-Purcell-Meiboom-Gill (CPMG) sequence] has been successfully used to\nidentify single nuclear spins and to resolve structure of nuclear spin\nclusters. Here, we design a new type of pulse sequences by replacing the\nrepetition unit (a single $\\pi$-pulse) of the CPMG sequence with a group of\nnonuniformly-spaced $\\pi$-pulses. Using nitrogen-vacancy center system in\ndiamond, we show that the designed pulse sequence improves the resolution of\nnuclear spin noise spectroscopy, and more information about the surrounding\nnuclear spins is extracted. The principle of dynamical decoupling design\nproposed in this paper is useful in many systems (e.g., defect spin qubit in\nsolids, trapped ion and superconducting qubit) for high-resolution noise\nspectroscopy."
    },
    {
        "anchor": "Helical edge states and topological phase transitions in phononic\n  systems using bi-layered lattices: We propose a framework to realize helical edge states in phononic systems\nusing two identical lattices with interlayer couplings between them. A\nmethodology is presented to systematically transform a quantum mechanical\nlattice which exhibits edge states to a phononic lattice, thereby developing a\nfamily of lattices with edge states. Parameter spaces with topological phase\nboundaries in the vicinity of the transformed system are illustrated to\ndemonstrate the robustness to mechanical imperfections. A potential realization\nin terms of fundamental mechanical building blocks is presented for the\nhexagonal and Lieb lattices. The lattices are composed of passive components\nand the building blocks are a set of disks and linear springs. Furthermore, by\nvarying the spring stiffness, topological phase transitions are observed,\nillustrating the potential for tunability of our lattices.",
        "positive": "Boundary Scattering in Ballistic Graphene: We report magnetotransport measurements in ballistic graphene/hexagonal boron\nnitride mesoscopic wires where the charge carrier mean free path is comparable\nto wire width $W$. Magnetoresistance curves show characteristic peak structures\nwhere the peak field scales with the ratio of cyclotron radius $R_\\textrm{c}$\nand wire width $W$ as $W/R_\\textrm{c} = 0.9 \\pm 0.1$, due to diffusive boundary\nscattering. The obtained proportionality constant between $R_\\textrm{c}$ and\n$W$ differs from that of a classical semiconductor 2D electron system where\n$W/R_\\textrm{c} = 0.55$."
    },
    {
        "anchor": "Dynamical polarization and plasmons in noncentrosymmetric metals: We study the dynamical polarization function and plasmon modes for spin-orbit\ncoupled noncentrosymmetric metals (NCMs). These systems have different Fermi\nsurface topology for Fermi energies above and below the spin degenerate point\nwhich is also known as the band touching point (BTP). We calculate the exact\ndynamical polarization function numerically and also provide its analytical\nexpression in the long wavelength limit. We obtain the plasmon dispersion\nwithin the framework of random phase approximation. In NCMs, there is a finite\nenergy gap in between intra and interband particle hole continuum (PHC) for\nvanishing excitation wavevector. In the long wavelength limit, the width of\ninterband PHC behaves differently for Fermi energies below and above the BTP as\na clear signature of the Fermi surface topology change. We find a single\nundamped optical plasmon mode lying in between the intra and interband PHC for\nFermi energies above and below the BTP. The plasmon mode below the BTP has\nsmaller velocity than that of above the BTP. It is interesting to find that as\nwe tune the Fermi energy around the BTP, the plasmon mode becomes damped within\na range of e-e interaction strength. For Fermi energies above and below the\nBTP, we also obtain an approximate analytical result of plasma frequency and\nplasmon dispersion which match well with their numerical counterparts in the\nlong wavelength limit. The plasmon dispersion is $\\propto q^2$ with $q$ being\nthe wave vector for plasmon excitation in the long wavelength limit. We find\nthat varying the carrier density with fixed e-e interaction strength or vice\nversa does not change the number of undamped plasmon mode, although damped\nplasmon modes can be more in number for some values of these parameters. We\ndemonstrate our results by calculating the loss function and optical\nconductivity which can be measured in experiments.",
        "positive": "Coulomb drag in compressible quantum Hall states: We consider the Coulomb drag between two layers of two-dimensional electronic\ngases subject to a strong magnetic field. We first focus on the case in which\nthe electronic density is such that the Landau level filling fraction $\\nu$ in\neach layer is at, or close to, $\\nu=1/2$. Discussing the coupling between the\nlayers in purely electronic terms, we show that the unique dependence of the\nlongitudinal conductivity on wave-vector, observed in surface acoustic waves\nexperiments, leads to a very slow decay of density fluctuations. Consequently,\nit has a crucial effect on the Coulomb drag, as manifested in the\ntransresistivity $\\rho_D$. We find that the transresistivity is very large\ncompared to its typical values at zero magnetic field, and that its temperature\ndependence is unique -- $\\rho_D \\propto T^{4/3}$. For filling factors at or\nclose to $1/4$ and $3/4$ the transresistivity has the same $T$-dependence, and\nis larger than at $\\nu = 1/2$. We calculate $\\rho_D$ for the $\\nu=3/2$ case and\npropose that it might shed light on the spin polarization of electrons at\n$\\nu=3/2$. We compare our results to recent calculations of $\\rho_D$ at\n$\\nu=1/2$ where a composite fermion approach was used and a\n$T^{4/3}$-dependence was obtained. We conclude that what appears in the\ncomposite fermion language to be drag induced by Chern-Simons interaction is,\nphysically, electronic Coulomb drag."
    },
    {
        "anchor": "Statistics of speckle patterns: We develop a general method for calculating statistical properties of the\nspeckle pattern of coherent waves propagating in disordered media. In some\naspects this method is similar to the Boltzmann-Langevin approach for the\ncalculation of classical fluctuations. We apply the method to the case where\nthe incident wave experiences many small angle scattering events during\npropagation, but the total angle change remains small. In many aspects our\nresults for this case are different from results previously known in the\nliterature. The correlation function of the wave intensity at two points\nseparated by a distance $r$, has a long range character. It decays as a power\nof $r$ and changes sign. We also consider sensitivities of the speckles to\nchanges of external parameters, such as the wave frequency and the incidence\nangle.",
        "positive": "Persistent current noise in normal and superconducting nanorings: We investigate fluctuations of persistent current (PC) in nanorings both with\nand without dissipation and decoherence. We demonstrate that such PC\nfluctuations may persist down to zero temperature provided there exists either\ninteraction with an external environment or an external (periodic) potential\nproduced, e.g., by quantum phase slips in superconducting nanorings. Provided\nquantum coherence is maintained in the system PC noise remains coherent and can\nbe tuned by an external magnetic flux $\\Phi_x$ piercing the ring. If quantum\ncoherence gets suppressed by interactions with a dissipative bath PC noise\nbecomes incoherent and $\\Phi_x$-independent."
    },
    {
        "anchor": "Mode mixing induced by disorder in graphene PNP junction in a magnetic\n  field: We study the electron transport through the graphene PNP junction under a\nmagnetic field and show that modes mixing plays an essential role. By using the\nnon-equilibrium Green's function method, the space distribution of the\nscattering state for a specific incident modes as well the elements of the\ntransmission and reflection coefficient matrixes are investigated. All elements\nof the transmission (reflection) coefficient matrixes are very different for a\nperfect PNP junction, but they are same at a disordered junction due to the\nmode mixing. The space distribution of the scattering state for the different\nincident modes also exhibit the similar behaviors, that they distinctly differ\nfrom each other in the perfect junction but are almost same in the disordered\njunction. For a unipolar junction, when the mode number in the center region is\nless than that in the left and right regions, the fluctuations of the total\ntransmission and reflection coefficients are zero, although each element has a\nlarge fluctuation. These results clearly indicate the occurrence of perfect\nmode mixing and it plays an essential role in a graphene PNP junction\ntransport.",
        "positive": "Complex plasmon-exciton dynamics revealed through quantum dot light\n  emission in a nanocavity: Plasmonic cavities can confine electromagnetic radiation to deep\nsub-wavelength regimes. This facilitates strong coupling phenomena to be\nobserved at the limit of individual quantum emitters. Here we report an\nextensive set of measurements of plasmonic cavities hosting one to a few\nsemiconductor quantum dots. Scattering spectra show Rabi splitting,\ndemonstrating that these devices are close to the strong coupling regime. Using\nHanbury Brown and Twiss interferometry, we observe non-classical emission,\nallowing us to directly determine the number of emitters in each device.\nSurprising features in photoluminescence spectra point to the contribution of\nmultiple excited states. Using model simulations based on an extended Jaynes\nCummings Hamiltonian, we find that the involvement of a dark state of the\nquantum dots explains the experimental findings. The coupling of quantum\nemitters to plasmonic cavities thus exposes complex relaxation pathways and\nemerges as an unconventional means to control dynamics of quantum states."
    },
    {
        "anchor": "Renormalization of the Mott gap by lattice entropy: The case of 1T-TaS2: In many transition-metal oxides and dichalcogenides, the electronic and\nlattice degrees of freedom are strongly coupled, giving rise to remarkable\nphenomena, such as metal-insulator transition (MIT) and charge-density wave\n(CDW) order. We study this interplay by tracing the instant electronic\nstructure under ab initio molecular dynamics. Applying this method to a 1T-TaS2\nlayer, we show that the CDW-triggered Mott gap undergoes a continuous reduction\nas the lattice temperature raises, despite a nearly constant CDW amplitude.\nBefore the CDW order undergoes a sharp first-order transition around the room\ntemperature, the dynamical CDW fluctuation already shrinks the Mott gap size by\nhalf. The gap size reduction is one order of magnitude larger than the lattice\ntemperature variation. Our calculation not only provides an important clue to\nunderstand the thermodynamics behavior in 1T-TaS2, but also demonstrates a\ngeneral approach to quantify the lattice entropy effect in MIT.",
        "positive": "Evidence for a Superfluid-to-solid Transition of Bilayer Excitons: The low-temperature phase diagram of a Bosonic system is predicted to contain\nan exotic quantum phase, called a supersolid, that is defined by broken\ntranslational symmetry and off-diagonal long-range order. This unique\ncombination of properties enables a seemingly paradoxical scenario where a\nbosonic solid exhibits dissipationless mass flow. However, despite decades of\nextensive efforts, experimental realization of such a supersolid phase remains\nelusive. In this work we report experimental observation of a\nsuperfluid-to-insulating transition in the bosonic system of spatially indirect\nexcitons in double layer graphene. Utilizing a variety of transport methods to\ncharacterize the superfluid-insulator phase boundary as a function of both\ndensity and temperature suggests the insulator to be a solid phase driven by\nrepulsive dipole-dipole interactions in the dilute limit. The exciton solid\nexhibits a unique melting transition, with the high-temperature phase\nrecovering a hallmark transport signature of off-diagonal long-range order,\nperfect Coulomb drag. The reentrant superfluid-like behaviour could indicate\nthe low temperature solid also corresponds to a quantum coherent phase."
    },
    {
        "anchor": "Domain wall automotion in three-dimensional magnetic helical\n  interconnectors: The fundamental limits currently faced by traditional computing devices\nnecessitate the exploration of new ways to store, compute and transmit\ninformation. Here, we propose a three-dimensional (3D) magnetic interconnector\nthat exploits geometry-driven automotion of domain walls (DWs), for the\ntransfer of magnetic information between functional magnetic planes. By\ncombining state-of-the-art 3D nanoprinting and standard physical vapor\ndeposition, we prototype 3D helical DW conduits. We observe the automotion of\nDWs by imaging their magnetic state under different field sequences using X-ray\nmicroscopy, observing a robust unidirectional motion of DWs from the bottom to\nthe top of the spirals. From experiments and micromagnetic simulations, we\ndetermine that the large thickness gradients present in the structure are the\nmain mechanism for 3D DW automotion. We obtain direct evidence of how this\ntailorable magnetic energy gradient is imprinted in the devices, and how it\ncompetes with pinning effects due to local changes in the energy landscape. Our\nwork also predicts how this effect could lead to high DW velocities, reaching\nthe Walker limit during automotion. This work provides new possibilities for\nefficient transfer of magnetic information in three dimensions.",
        "positive": "All-optical magnetization switching by two-frequency pulses using the\n  plasmon-induced inverse Faraday effect in a magneto-plasmonic structure: In this Letter we study the generation of quasi-static magnetic fields by the\nplasmon-induced inverse Faraday effect and propose a magneto-optical waveguide\nstructure for achieving magnetization switching at sub-ps time in a\nnano-confined magneto-optical structure. In particular we show that the\ndirection of the generated quasi-static field in a magneto-optical dielectric\ncavity side-coupled to a metal-insulator-metal (MIM) waveguide depends\nsensitively on the wavelength of the surface plasmon polaritions (SPP). This\nphenomenon could open up a new energy-efficient ultrafast method for\nnano-confined all-optical magnetization switching by two-frequency pulses."
    },
    {
        "anchor": "Control of biaxial strain in single-layer Molybdenite using local\n  thermal expansion of the substrate: Single-layer MoS2 is a direct-gap semiconductor whose electronic band\nstructure strongly depends on the strain applied to its crystal lattice. While\nuniaxial strain can be easily applied in a controlled way, e.g., by bending of\na flexible substrate with the atomically thin MoS2 layer on top, experimental\nrealization of biaxial strain is more challenging. Here, we exploit the large\nmismatch between the thermal expansion coefficients of MoS2 and a\nsilicone-based substrate to apply a controllable biaxial tensile strain by\nheating the substrate with a focused laser. The effect of this biaxial strain\nis directly observable in optical spectroscopy as a redshift of the MoS2\nphotoluminescence. We also demonstrate the potential of this method to engineer\nmore complex strain patterns by employing highly absorptive features on the\nsubstrate to achieve non-uniform heat profiles. By comparison of the observed\nredshift to strain-dependent band structure calculations, we estimate the\nbiaxial strain applied by the silicone-based substrate to be up to 0.2 percent,\ncorresponding to a band gap modulation of 105 meV per percentage of biaxial\ntensile strain.",
        "positive": "Spin Transitions in Graphene Butterflies at an Integer Filling Factor: Recent experiments on the role of electron-electron interactions in fractal\nDirac systems have revealed a host of interesting effects, in particular, the\nunique nature of the magnetic field dependence of butterfly gaps in graphene.\nThe novel gap structure observed in the integer quantum Hall effect is quite\nintriguing [Nat. Phys. 10, 525 (2014)], where one observes a suppression of the\nferromagnetic state at one value of the commensurable flux but a reentrant\nferromagnetic state at another. Our present work that includes the interplay\nbetween the electron-electron interaction and the periodic potential, explains\nthe underlying physical processes that can lead to such a unique behavior of\nthe butterfly gaps in that system where spin flip transitions are involved in\nthe ground state."
    },
    {
        "anchor": "Interacting Dirac liquid in three-dimensional semimetals: We study theoretically the properties of the interacting Dirac liquid, a\nnovel three-dimensional many-body system which was recently experimentally\nrealized and in which the electrons have a chiral linear relativistic\ndispersion and a mutual Coulomb interaction. We find that the \"intrinsic\" Dirac\nliquid, where the Fermi energy lies exactly at the nodes of the band\ndispersion, displays unusual Fermi liquid properties similar to graphene,\nwhereas the \"extrinsic\" system with finite detuning or doping behaves as a\nstandard Landau Fermi liquid. We present analytical and numerical results for\nthe self-energy and spectral function based on both Hartree-Fock and the random\nphase approximation (RPA) theories and compute the quasiparticle lifetime,\nresidue, and renormalized Fermi velocity of the extrinsic Dirac liquid. A full\nnumerical calculation of the extrinsic RPA spectral function indicates that the\nFermi liquid description breaks down for large-energy excitations. Furthermore,\nwe find an additional plasmaron quasiparticle sideband in the spectral function\nwhich is discontinuous around the Fermi energy. Our predictions should be\nobservable in ARPES and STM measurements.",
        "positive": "Many-impurity scattering on the surface of a topological insulator: We theoretically address the impact of a random distribution of non-magnetic\nimpurities on the surface states formed at the interface between a trivial and\na topological insulator. The interaction of electrons with the impurities is\naccounted for by a separable pseudo-potential method that allows us to obtain\nclosed expressions for the density of states. Spectral properties of surface\nstates are assessed by means of the Green's function averaged over disorder\nrealizations. For comparison purposes, the configurationally averaged Green's\nfunction is calculated by means of two different self-consistent methods,\nnamely the self-consistent Born approximation (SCBA) and the coherent potential\napproximation (CPA). The latter is often regarded as the best single-site\ntheory for the study of the spectral properties of disordered systems. However,\nalthough a large number of works employ the SCBA for the analysis of\nmany-impurity scattering on the surface of a topological insulator, CPA studies\nof the same problem are scarce in the literature. In this work we find that the\nSCBA overestimates the impact of the random distribution of impurities on the\nspectral properties of surface states compared to the CPA predictions. The\ndifference is more pronounced when increasing the magnitude of the disorder."
    },
    {
        "anchor": "Hybrid scale-free skin effect in non-Hermitian systems: A transfer\n  matrix approach: Surpassing the individual characteristics of the non-Hermitian skin effect\n(NHSE) and the scale-free (SF) effect observed recently, we systematically\nexploit the exponential decay behavior of bulk eigenstates via the transfer\nmatrix approach in non-Hermitian systems. We concentrate on one-dimensional\n(1D) finite-size non-Hermitian systems with 2*2 transfer matrices in either the\nabsence or presence of the boundary impurity. We analytically unveil that the\nunidirectional SF effect emerges with the singular transfer matrices, while the\nhybrid scale-free skin (SFS) effect appears with the nonsingular transfer\nmatrices even when an open boundary condition (OBC) is imposed. The\nunidirectional SF effect exceeds the scope of the SF effect in previous works,\nwhile the hybrid SFS effect is an interesting interplay between the skin effect\nand the SF effect in finite-size systems. Our results reveal that the skin\neffect under the OBC prevails when it coexists with the SF effect as the system\napproaches the thermodynamic limit in the presence of the hybrid SFS effect.\nOur approach paves the way for rigorous and unified explorations of the skin\nand SF effects in both Hermitian and non-Hermitian systems with generic\nboundary conditions.",
        "positive": "Transversal magnetotransport in Weyl semimetals: Exact numerical\n  approach: Magnetotransport experiments on Weyl semimetals are essential for\ninvestigating the intriguing topological and low-energy properties of Weyl\nnodes. If the transport direction is perpendicular to the applied magnetic\nfield, experiments have shown a large positive magnetoresistance. In this work,\nwe present a theoretical scattering matrix approach to transversal\nmagnetotransport in a Weyl node. Our numerical method confirms and goes beyond\nthe existing perturbative analytical approach by treating disorder exactly. It\nis formulated in real space and is applicable to mesoscopic samples as well as\nin the bulk limit. In particular, we study the case of clean and strongly\ndisordered samples."
    },
    {
        "anchor": "Mechanics of thermally fluctuating membranes: Besides having unique electronic properties, graphene is claimed to be the\nstrongest material in nature. In the press release of the Nobel committee it is\nclaimed that a hammock made of a squared meter of one-atom thick graphene could\nsustain the wight of a 4 kg cat. More practically important are applications of\ngraphene like scaffolds and sensors which are crucially dependent on the\nmechanical strength. Meter-sized graphene is even being considered for the\nlightsails in the starshot project to reach the star alpha centaury. The\npredicted strength of graphene is based on its very large Young modulus which\nis, per atomic layer, much larger than that of steel. This reasoning however\nwould apply to conventional thin plates but does not take into account the\npeculiar properties of graphene as a thermally fluctuating crystalline\nmembrane. It was shown recently both experimentally and theoretically that\nthermal fluctuations lead to a dramatic reduction of the Young modulus and\nincrease of the bending rigidity for micron-sized graphene samples in\ncomparison with atomic scale values. This makes the use of the standard\nF\\\"oppl-von Karman elasticity (FvK) theory for thin plates not directly\napplicable to graphene and other single atomic layer membranes. This fact is\nimportant because the current interpretation of experimental results is based\non the FvK theory. In particular, we show that the FvK-derived Schwerin\nequation, routinely used to derive the Young modulus from indentation\nexperiments has to be essentially modified for graphene at room temperature and\nfor micron sized samples. Based on scaling analysis and atomistic simulation we\ninvestigate the mechanics of graphene under transverse load up to breaking. We\ndetermine the limits of applicability of the FvK theory and provide\nquantitative estimates for the different regimes.",
        "positive": "Orbital magnetoelectric effect in nanoribbons of transition metal\n  dichalcogenides: The orbital magnetoelectric effect (OME) generically refers to the appearance\nof an orbital magnetization induced by an applied electric field. Here, we show\nthat nanoribbons of transition metal dichalcogenides (TMDs) with zigzag (ZZ)\nedges may exhibit a sizeable OME activated by an electric field applied along\nthe ribbons' axis. We examine nanoribbons extracted from a monolayer (1L) and a\nbilayer (2L) of MoS$_2$ in the trigonal (H) structural phase. Transverse\nprofiles of the induced orbital angular momentum accumulations are calculated\nto first order in the longitudinally applied electric field. Our results show\nthat close to the nanoribbon's edge-state crossings energy, the orbital angular\nmomentum accumulations take place mainly around the ribbons' edges. They have\ntwo contributions: one arising from the orbital Hall effect (OHE) and the other\nconsists in the OME. The former is transversely anti-symmetric with respect to\nthe principal axis of the nanoribbon, whereas the latter is symmetric, and\nhence responsible for the resultant orbital magnetization induced in the\nsystem. We found that the orbital accumulation originating from the OHE for the\n1L-nanoribbon is approximately half that of a 2L-nanoribbon. Furthermore, while\nthe OME can reach fairly high values in 1L-TMD nanoribbons, it vanishes in the\n2L ones that preserve spatial inversion symmetry.The microscopic features that\njustify our findings are also discussed."
    },
    {
        "anchor": "Spin-orbit scattering in superconducting nanoparticles: We review interaction effects in chaotic metallic nanoparticles. Their\nsingle-particle Hamiltonian is described by the proper random-matrix ensemble\nwhile the dominant interaction terms are invariants under a change of the\nsingle-particle basis. In the absence of spin-orbit scattering, the non-trivial\ninvariants consist of a pairing interaction, which leads to superconductivity\nin the bulk, and a ferromagnetic exchange interaction. Spin-orbit scattering\nbreaks spin-rotation invariance and when it is sufficiently strong, the only\ndominant nontrivial interaction is the pairing interaction. We discuss how the\nmagnetic response of discrete energy levels of the nanoparticle (which can be\nmeasured in single-electron tunneling spectroscopy experiments) is affected by\nsuch pairing correlations and how it can provide a signature of pairing\ncorrelations. We also consider the spin susceptibility of the nanoparticle and\ndiscuss how spin-orbit scattering changes the signatures of pairing\ncorrelations in this observable.",
        "positive": "Extrinsic Spin Hall Effect Induced by Iridium Impurities in Copper: We study the extrinsic spin Hall effect induced by Ir impurities in Cu by\ninjecting a pure spin current into a CuIr wire from a lateral spin valve\nstructure. While no spin Hall effect is observed without Ir impurity, the spin\nHall resistivity of CuIr increases linearly with the impurity concentration.\nThe spin Hall angle of CuIr, $(2.1 \\pm 0.6)$% throughout the concentration\nrange between 1% and 12%, is practically independent of temperature. These\nresults represent a clear example of predominant skew scattering extrinsic\ncontribution to the spin Hall effect in a nonmagnetic alloy."
    },
    {
        "anchor": "Current-induced magnon trapping in spin torque oscillation: Spin torque nano-oscillators realized by magnetization dynamics trapped in a\ncurrent-induced potential are reported. We fabricated Ni$_{81}$Fe$_{19}$/Pt\nnanostructures and measured current-induced microwave emission from the\nstructures. The result shows an increase in the magnitude and spectral\nnarrowing of the microwave emission. We demonstrate that the current-induced\nmagnetic field suppresses magnon radiation loss and significantly reduces the\nlinewidth and the threshold current required for the spin torque oscillation.",
        "positive": "Magnetoresistance of a 2D electron gas caused by electron interactions\n  in the transition from the diffusive to the ballistic regime: On a high-mobility 2D electron gas we have observed, in strong magnetic\nfields (omega_{c} tau > 1), a parabolic negative magnetoresistance caused by\nelectron-electron interactions in the regime of k_{B} T tau / hbar ~ 1, which\nis the transition from the diffusive to the ballistic regime. From the\ntemperature dependence of this magnetoresistance the interaction correction to\nthe conductivity delta sigma_{xx}^{ee}(T) is obtained in the situation of a\nlong-range fluctuation potential and strong magnetic field. The results are\ncompared with predictions of the new theory of interaction-induced\nmagnetoresistance."
    },
    {
        "anchor": "Electronic Conduction Through Monolayer Amorphous Carbon Nano-Junctions: In molecular electronic conduction, exotic lattice morphologies often give\nrise to exotic behaviors. Among 2D systems, graphene is a notable example.\nRecently, a stable amorphous version of graphene called Monolayer Amorphous\nCarbon (MAC) was synthesized. MAC poses a new set of questions regarding the\neffects of disorder on conduction. In this Letter, we perform ensemble-level\ncomputational analysis of the coherent electronic transmission through MAC\nnano-fragments in search of defining characteristics. Our analysis, relying on\na semi-empirical Hamiltonian (Pariser-Parr-Pople) and Landauer theory, showed\nthat states near the Fermi energy ($E_F$) in MAC inherit partial\ncharacteristics of analogous surface states in graphene nano-fragments. Away\nfrom $E_F$, current is carried by a set of delocalized states which transition\ninto a subset of insulating interior states at the band edges. Finally, we also\nfound that quantum interference between the frontier orbitals is a common\nfeature among MAC nano-fragments.",
        "positive": "Scaling analysis of Kondo screening cloud in a mesoscopic ring with an\n  embedded quantum dot: The Kondo effect is theoretically studied in a quantum dot embedded in a\nmesoscopic ring. The ring is connected to two external leads, which enables the\ntransport measurement. Using the \"poor man's\" scaling method, we obtain\nanalytical expressions of the Kondo temperature T_K as a function of the\nAharonov-Bohm phase \\phi by the magnetic flux penetrating the ring. In this\nKondo problem, there are two characteristic lengths. One is the screening\nlength of the charge fluctuation, L_c=\\hbar v_F/ |\\epsilon_0|, where v_F is the\nFermi velocity and \\epsilon_0 is the energy level in the quantum dot. The other\nis the screening length of spin fluctuation, i.e., size of Kondo screening\ncloud, L_K=\\hbar v_F/ T_K. We obtain different expressions of T_K(\\phi) for (i)\nL_c \\ll L_K \\ll L, (ii) L_c \\ll L \\ll L_K, and (iii) L \\ll L_c \\ll L_K, where L\nis the size of the ring. T_K is markedly modulated by \\phi in cases (ii) and\n(iii), whereas it hardly depends on \\phi in case (i). We also derive\nlogarithmic corrections to the conductance at temperature T\\gg T_K and an\nanalytical expression of the conductance at T\\ll T_K, on the basis of the\nscaling analysis."
    },
    {
        "anchor": "Trapping Abelian anyons in fractional quantum Hall droplets: We study the trapping of Abelian anyons (quasiholes and quasiparticles) by a\nlocal potential (e.g., induced by an AFM tip) in a microscopic model of\nfractional quantum Hall liquids with long-range Coulomb interaction and edge\nconfining potential. We find, in particular, at Laughlin filling fraction $\\nu\n= 1/3$, both quasihole and quasiparticle states can emerge as the ground state\nof the system in the presence of the trapping potential. As expected, we find\nthe presence of an Abelian quasihole has no effect on the edge spectrum of the\nquantum liquid, unlike in the non-Abelian case [Phys. Rev. Lett. {\\bf 97},\n256804 (2006)]. Although quasiholes and quasiparticles can emerge generically\nin the system, their stability depends on the strength of the confining\npotential, the strength and the range of the trapping potential. We discuss the\nrelevance of the calculation to the high-accuracy generation and control of\nindividual anyons in potential experiments, in particular, in the context of\ntopological quantum computing.",
        "positive": "Electromagnetic signatures of the chiral anomaly in Weyl semimetals: Weyl semimetals are predicted to realize the three-dimensional axial anomaly\nfirst discussed in particle physics. The anomaly leads to unusual transport\nphenomena such as the chiral magnetic effect in which an applied magnetic field\ninduces a current parallel to the field. Here we investigate diagnostics of the\naxial anomaly based on the fundamental equations of axion electrodynamics. We\nfind that materials with Weyl nodes of opposite chirality and finite energy\nseparation immersed in a uniform magnetic field exhibit an anomaly-induced\noscillatory magnetic field with a period set by the chemical potential\ndifference of the nodes. In the case where a chemical potential imbalance is\ncreated by applying parallel electric and magnetic fields, we find a\nsuppression of the magnetic field component parallel to the electric field\ninside the material for rectangular samples, suggesting that the chiral\nmagnetic current opposes this imbalance. For cylindrical geometries, we instead\nfind an enhancement of this magnetic field component along with an\nanomaly-induced azimuthal component. We propose experiments to detect such\nmagnetic signatures of the axial anomaly."
    },
    {
        "anchor": "The Role of Self-Torques in Transition Metal Dichalcogenide/Ferromagnet\n  Bilayers: Recently, transition metal dichalcogenides (TMDs) have been extensively\nstudied for their efficient spin-orbit torque generation in TMD/ferromagnetic\nbilayers, owing to their large spin-orbit coupling, variety in crystal\nsymmetries, and pristine interfaces. Although the TMD layer was considered\nessential for the generation of the observed SOTs, recent reports show the\npresence of a self-torque in single-layer ferromagnetic devices with magnitudes\ncomparable to TMD/ferromagnetic devices. Here, we perform second-harmonic Hall\nSOT measurements on metal-organic chemical vapor deposition (MOCVD) grown\nMoS$_{2}$/permalloy/Al$_{2}$O$_{3}$ devices and compare them to a single-layer\npermalloy/Al$_{2}$O$_{3}$ device to accurately disentangle the role of\nself-torques from contributions from the TMD layer. We report a damping-like\nself-torque conductivity of opposite sign in our single-layer\npermalloy/Al$_{2}$O$_{3}$ device compared to one\nMoS$_{2}$/permalloy/Al$_{2}$O$_{3}$ device, and find no significant one for all\nother MoS$_{2}$/permalloy/Al$_{2}$O$_{3}$ devices. This indicates a competition\nbetween the self-torque and the torque arising from the TMD layer, which would\nreduce the observed torque in these bilayers. In addition, we find a field-like\nspin-torque conductivity of comparable magnitude to control\nMoS$_{2}$/permalloy/Al$_{2}$O$_{3}$ devices, indicating only a minor role of\nthe MoS$_{2}$ layer. Finally, we find a linear dependence of the SOT\nconductivity on the Hall bar leg/channel width ratio of our devices, indicating\nthat the Hall bar dimensions are of significant importance for the reported SOT\nstrength. Our results accentuate the importance of delicate details, like\ndevice asymmetry, Hall bar dimensions, and self-torque generation, for the\ncorrect disentanglement of the microscopic origins underlying the SOTs,\nessential for future energy-efficient spintronic applications.",
        "positive": "Extended orbital modeling of spin qubits in double quantum dots: Orbital modeling of two electron spins confined in a double quantum dot is\nrevisited. We develop an extended Hund Mulliken approach that includes excited\norbitals, allowing for a triplet configuration with both electrons residing in\na single dot. This model improves the reliability and applicability of the\nstandard Hund Mulliken approximation, while remaining largely analytical, thus\nit enables us to identify the mechanisms behind the exchange coupling dynamics\nthat we find. In particular, our calculations are in close agreement with\nexchange values that were recently measured at a high interdot bias regime,\nwhere the double occupancy triplet configuration is energetically accessible,\ndemonstrating reduced sensitivity to bias fluctuations, while maintaining the\nlarge exchange needed for fast gating."
    },
    {
        "anchor": "Signatures of phase-coherent transport and the role of quantum\n  fluctuations in the dynamical Coulomb blockade regime: Josephson junctions operated in the dynamical Coulomb blockade regime\nrecently gained an significant amount of attention as central building block in\nconcepts to demonstrate the non-Abelian character of Majorana fermions. Its\nphysical properties are strongly affected by the intimate interplay of\nintrinsic quantum fluctuations and environmentally-induced quantum fluctuations\neach of which promoting different Cooper pair transport mechanisms at small\nvoltages around zero. To shed light on the detailed transport mechanisms\noccurring in this type of junction, we performed voltage-biased measurements on\nthe small-capacitance Josephson junction of a scanning tunneling microscope at\nmilli-Kelvin temperatures. The low voltage-regime of experimental\ncurrent-voltage characteristics can be modeled by the two complementary\ndescriptions of phase coherent and incoherent Cooper pair transport, signaling\nthe occurrence of qualitatively different transport mechanisms. This\nobservation receives further support from analyzing the calculated Fano factor\nof the current noise as a probe for correlations in Cooper pair transport,\nfollowing a theoretical proposal. Together our experimental observations and\nrelated data analysis provide a clear signature of coherent Cooper pair\ntransport along with the absence of perfect charge quantized transport around\nzero voltage, as well as of incoherent Cooper pair transport towards higher\nvoltages.",
        "positive": "Multitip scanning gate microscopy for ballistic transport studies in\n  systems with two-dimensional electron gas: We consider conductance mapping of systems based on the two-dimensional\nelectron gas with scanning gate microscopy using two and more tips of the\natomic force microscope. The paper contains results of numerical simulations\nfor a model tip potential with a proposal of a few procedures for extraction\nand manipulation the ballistic transport properties. In particular, we\ndemonstrate that the multi-tip techniques can be used for readout of the Fermi\nwavelength, detection of potential defects, filtering specific transverse\nmodes, tuning the system into resonant conditions under which a stable map of a\nlocal density of states can be extracted from conductance maps using a third\ntip."
    },
    {
        "anchor": "An optimized TEM specimen preparation method of quantum nanostructures: Electron transparent TEM lamella with unaltered microstructure and chemistry\nis the prerequisite for successful TEM explorations. Currently, TEM specimen\npreparation of quantum nanostructures, such as quantum dots (QDs), remains a\nchallenge. In this work, we optimize the sample-preparation routine for\nachieving high-quality TEM specimens consisting of SrRuO3 (SRO) QDs grown on\nSrTiO3 (STO) substrates. We demonstrate that a combination of ion-beam-milling\ntechniques can produce higher-quality specimens of quantum nanostructures\ncompared to TEM specimens prepared by a combination of tripod polishing\nfollowed by Ar+ ion milling. In the proposed method, simultaneous imaging in a\nfocused ion-beam device enables accurate positioning of the QD regions and\nassures the presence of dots in the thin lamella by cutting the sample inclined\nby 5{\\deg} relative to the dots array. Furthermore, the preparation of TEM\nlamellae with several large electron-transparent regions that are separated by\nthicker walls effectively reduces the bending of the specimen and offers broad\nthin areas. The final use of a NanoMill efficiently removes the amorphous layer\nwithout introducing any additional damage.",
        "positive": "Acoustic plasmons at the crossover between the collisionless and\n  hydrodynamic regimes in two-dimensional electron liquids: Hydrodynamic flow in two-dimensional electron systems has so far been probed\nonly by dc transport and scanning gate microscopy measurements. In this work we\ndiscuss theoretically signatures of the hydrodynamic regime in near-field\noptical microscopy. We analyze the dispersion of acoustic plasmon modes in\ntwo-dimensional electron liquids using a non-local conductivity that takes into\naccount the effects of (momentum-conserving) electron-electron collisions,\n(momentum-relaxing) electron-phonon and electron-impurity collisions, and\nmany-body interactions beyond the celebrated Random Phase Approximation. We\nderive the dispersion and, most importantly, the damping of acoustic plasmon\nmodes and their coupling to a near-field probe, identifying key experimental\nsignatures of the crossover between collisionless and hydrodynamic regimes."
    },
    {
        "anchor": "Reduction of thermal conductance by coherent phonon scattering in\n  two-dimensional phononic crystals of different lattice types: The impact of lattice type, period, porosity and thickness of two-dimensional\nsilicon phononic crystals on the reduction of thermal conductance by coherent\nmodification of phonon dispersion is investigated using the theory of\nelasticity and finite element method. Increase in the period and porosity of\nthe phononic crystal affects the group velocity and phonon density of states\nand, as a consequence, reduces the in-plane thermal conductance of the\nstructure as compared to unpatterned membrane. This reduction does not depend\nsignificantly on the lattice type and thickness of phononic crystals. Moreover,\nthe reduction is strongly temperature dependent and strengthens as the\ntemperature is increased.",
        "positive": "Spin dynamics of $3d$ and $4d$ impurities embedded in prototypical\n  topological insulators: Topological insulators are insulating bulk materials hosting conducting\nsurface states. Their magnetic doping breaks time-reversal symmetry and\ngenerates numerous interesting effects such as dissipationless transport.\nNonetheless, their dynamical properties are still poorly understood. Here, we\nperform a systematic investigation of transverse spin excitations of $3d$ and\n$4d$ single impurities embedded in two prototypical topological insulators\n(Bi$_2$Te$_3$ and Bi$_2$Se$_3$). The impurity-induced states within the bulk\ngap of the topological insulators are found to have a drastic impact on the\nspin excitation spectra, resulting in very high lifetimes reaching up to\n${microseconds}$. An intuitive picture of the spin dynamics is obtained by\nmapping onto a generalized Landau-Lifshitz-Gilbert phenomenological model. The\nfirst quantity extracted from this mapping procedure is the magnetic anisotropy\nenergy, which is then compared to the one provided by the magnetic force\ntheorem. This uncovers some difficulties encountered with the latter, which can\nprovide erroneous results for impurities with a high density of states at the\nFermi energy. Moreover, the Gilbert damping and nutation tensors are obtained.\nThe nutation effects can lead to a non-negligible shift in the spin excitation\nresonance in the high-frequency regime. Finally, we study the impact of the\nsurface state on the spin dynamics, which may be severely altered due to the\nrepositioning of the impurity-induced state in comparison to the bulk case. Our\nsystematic investigation of this series of magnetic impurities sheds light on\ntheir spin dynamics within topological insulators, with implications for\navailable and future experimental studies as, for instance, on the viability of\nusing such impurities for solid-state qubits."
    },
    {
        "anchor": "Optical Hall conductivity in 2DEG and graphene QHE systems: We have revealed from a numerical study that the Hall plateaus are retained\nin the optical Hall conductivity $\\sigma_{xy}(\\omega)$ in the ac ($\\sim$ THz)\nregime in both of the ordinary two-dimensional electron gas and graphene in the\nquantum Hall regime, although the plateau height in ac deviates from integer\nmultiples of $e^2/h$. The effect remains unexpectedly robust against a\nsignificant strength of disorder, which we attribute to an effect of\nlocalization. We predict the ac Hall plateaus are observable through the\nFaraday rotation with the rotation angle characterized by the fine-structure\nconstant $\\alpha$. In this paper we clarify the relationship between plateau\nstructures and the disorder strength by performing numerical calculation.",
        "positive": "Radio-frequency C-V measurements with sub-attofarad sensitivity: We demonstrate the use of radio-frequency (rf) resonators to measure the\ncapacitance of nano-scale semiconducting devices in field-effect transistor\nconfigurations. The rf resonator is attached to the gate or the lead of the\ndevice. Consequently, tuning the carrier density in the conducting channel of\nthe device affects the resonance frequency, quantitatively reflecting its\ncapacitance. We test the measurement method on InSb and InAs nanowires at\ndilution-refrigerator temperatures. The measured capacitances are consistent\nwith those inferred from the periodicity of the Coulomb blockade of quantum\ndots realized in the same devices. In an implementation of the resonator using\nan off-chip superconducting spiral inductor we find sensitivity values reaching\ndown to 75~zF/$\\sqHz$ at 1~kHz measurement bandwidth, and noise down to 0.45~aF\nat 1~Hz bandwidth. We estimate the sensitivity of the method for a number of\nother implementations. In particular we predict typical sensitivity of about\n40~zF/$\\sqHz$ at room temperature with a resonator comprised of off-the-shelf\ncomponents. Of several proposed applications, we demonstrate two: the\ncapacitance measurement of several identical 80~nm-wide gates with a single\nresonator, and the field-effect mobility measurement of an individual nanowire\nwith the gate capacitance measured in-situ."
    },
    {
        "anchor": "Reproduction of the charge density wave phase diagram in\n  $1T$-$\\mathrm{TiSe}_2$ exposes its excitonic character: Recent experiments suggest that excitonic degrees of freedom play an\nimportant role in precipitating the charge density wave (CDW) transition in\n$1T$-$\\mathrm{TiSe}_2$. Through systematic calculations of the electronic and\nphonon spectrum based on density functional perturbation theory, we show that\nthe predicted critical doping of the CDW phase overshoots the experimental\nvalue by 1 order of magnitude. In contrast, an independent self-consistent\nmany-body calculation of the excitonic order parameter and renormalized band\nstructure is able to capture the experimental phase diagram in extremely good\nqualitative and quantitative agreement. This demonstrates that\nelectron-electron interactions and the excitonic instability arising from\ndirect electron-hole coupling are pivotal to accurately describe the nature of\nthe CDW in this system. This has important implications to understand the\nemergence of superconductivity within the CDW phase of this and related\nsystems.",
        "positive": "Quantum Measurement of a Coupled Nanomechanical Resonator -- Cooper-Pair\n  Box System: We show two effects as a result of considering the second-order correction to\nthe spectrum of a nanomechanical resonator electrostatically coupled to a\nCooper-pair box. The spectrum of the Cooper-pair box is modified in a way which\ndepends on the Fock state of the resonator. Similarly, the frequency of the\nresonator becomes dependent on the state of the Cooper-pair box. We consider\nwhether these frequency shifts could be utilized to prepare the nanomechanical\nresonator in a Fock state, to perform a quantum non-demolition measurement of\nthe resonator Fock state, and to distinguish the phase states of the\nCooper-pair box."
    },
    {
        "anchor": "Electron transport in polycyclic hydrocarbon molecules: A study of shot\n  noise contribution to the power spectrum: We study electron transport in polycyclic hydrocarbon molecules attached to\ntwo semi-infinite one-dimensional metallic electrodes by the use of Green's\nfunction formalism. Parametric calculations based on the tight-binding\nframework are given to investigate the transport properties through such\nmolecular bridges. In this context we also discuss noise power of current\nfluctuations and focus our attention on the shot noise contribution to the\npower spectrum. The electron transport properties are significantly influenced\nby (a) length of the molecule, (b) molecule-electrode interface geometry and\n(c) molecular coupling strength to the electrodes.",
        "positive": "In-Situ Contacting and Current-Injection into Samples in Photoemission\n  Electron Microscopes: Studying the interaction of spin-polarized currents with the magnetization\nconfiguration is of high interest due to the possible applications and the\nnovel physics involved. High resolution magnetic imaging is one of the key\ntechniques necessary for a better understanding of these effects. Here we\npresent an extension to a magnetic microscope that allows for in-situ current\ninjection into the structure investigated and furthermore for the study of\ncurrent induced magnetization changes during pulsed current injection. The\ndeveloped setup is highly flexible and can be used for a wide range of\ninvestigations. Examples of current-induced domain wall motion and vortex core\ndisplacements measured using this setup are presented."
    },
    {
        "anchor": "Thermal Stability of Diamond-Like Carbon Nanothreads: The thermally activated fracture processes in the carbon backbone of\ndiamond-like carbon nanothreads and the hydrogen desorption from them has been\nstudied by the molecular dynamics method. Specifically, the temperature\ndependence of the characteristic desorption time at T = 1700-2800 K has been\ndetermined. The activation energy and frequency factor in the Arrhenius formula\nfor the desorption rate are found. This allows estimating the desorption time\nat any temperature. The mechanical stiffness of nanothreads is calculated.",
        "positive": "Terahertz probing of anisotropic conductivity and morphology of CuMnAs\n  epitaxial thin films: Antiferromagnetic CuMnAs thin films have attracted attention since the\ndiscovery of the manipulation of their magnetic structure via electrical,\noptical, and terahertz pulses of electric fields, enabling convenient\napproaches to the switching between magnetoresistive states of the film for the\ninformation storage. However, the magnetic structure and, thus, the efficiency\nof the manipulation can be affected by the film morphology and growth defects.\nIn this study, we investigate the properties of CuMnAs thin films by probing\nthe defect-related uniaxial anisotropy of electric conductivity by contact-free\nterahertz transmission spectroscopy. We show that the terahertz measurements\nconveniently detect the conductivity anisotropy, that are consistent with\nconventional DC Hall-bar measurements. Moreover, the terahertz technique allows\nfor considerably finer determination of anisotropy axes and it is less\nsensitive to the local film degradation. Thanks to the averaging over a large\ndetection area, the THz probing also allows for an analysis of strongly\nnon-uniform thin films. Using scanning near-field terahertz and electron\nmicroscopies, we relate the observed anisotropic conductivity of CuMnAs to the\nelongation and orientation of growth defects, which influence the local\nmicroscopic conductivity. We also demonstrate control over the morphology of\ndefects by using vicinal substrates."
    },
    {
        "anchor": "Ground-State Magnetization for Interacting Fermions in a Disordered\n  Potential : Kinetic Energy, Exchange Interaction and Off-Diagonal\n  Fluctuations: We study a model of interacting fermions in a disordered potential, which is\nassumed to generate uniformly fluctuating interaction matrix elements. We show\nthat the ground state magnetization is systematically decreased by off-diagonal\nfluctuations of the interaction matrix elements. This effect is neglected in\nthe Stoner picture of itinerant ferromagnetism in which the ground-state\nmagnetization is simply determined by the balance between ferromagnetic\nexchange and kinetic energy, and increasing the interaction strength always\nfavors ferromagnetism. The physical origin of the demagnetizing effect of\ninteraction fluctuations is the larger number of final states available for\ninteraction-induced scattering in the lower spin sectors of the Hilbert space.\nWe analyze the energetic role played by these fluctuations in the limits of\nsmall and large interaction $U$. In the small $U$ limit we do second-order\nperturbation theory and identify explicitly transitions which are allowed for\nminimal spin and forbidden for higher spin. These transitions then on average\nlower the energy of the minimal spin ground state with respect to higher spin.\nFor large interactions $U$ we amplify on our earlier work [Ph. Jacquod and A.D.\nStone, Phys. Rev. Lett. 84, 3938 (2000)] which showed that minimal spin is\nfavored due to a larger broadening of the many-body density of states in the\nlow-spin sectors. Numerical results are presented in both limits.",
        "positive": "Theory of quantum noise detectors based on resonant tunneling: We propose to use the phenomenon of resonant tunneling for the detection of\nnoise. The main idea of this method relies on the effect of homogeneous\nbroadening of the resonant tunneling peak induced by the emission and\nabsorption of collective charge excitations in the measurement circuit. In\nthermal equilibrium, the signal to noise ratio of the detector as a function of\nthe detector bandwidth (the detector function) is given by the universal\nhyperbolic tangent, which is the statement of the fluctuation-dissipation\ntheorem. The universality breaks down if non-equilibrium processes take place\nin the measurement circuit. We propose the theory of this phenomenon and make\npredictions for the detector function in case when non-equilibrium noise is\ncreated by a mesoscopic conductor. We investigate measurement circuit effects\nand prove the universality of the classical noise detection. Finally, we\nevaluate the contribution of the third cumulant of current and make suggestions\nof how it can be measured."
    },
    {
        "anchor": "Feasibility of measurement-based braiding in the quasi-Majorana regime\n  of semiconductor-superconductor heterostructures: We discuss the feasibility of measurement-based braiding in\nsemiconductor-superconductor (SM-SC) heterostructures in the so-called\nquasi-Majorana regime $-$ the topologically-trivial regime due to\npartially-separated Andreev bound states (ps-ABSs). These low energy ABSs\nconsist of component Majorana bound states (quasi-Majorana modes) that are\nspatially separated by a length scale smaller than the length of the system, in\ncontrast with the Majorana zero modes (MZMs), which are separated by the length\nof the wire. In the quasi-Majorana regime, the ZBCPs appear to be robust to\nvarious perturbations as long as the energy splitting of the ps-ABS is less\nthan the typical width $\\e_w$ of the low-energy conductance peaks $\\e_w$.\nHowever, the feasibility of measurement-based braiding depends on a different\nenergy scale $\\e_m$. In this paper we show that it is possible to prepare the\nSM-SC system in the quasi-Majorana regime with energy splittings below the\n$\\e_m$ threshold, so that measurement-based braiding is possible in principle.\nStarting with ps-ABSs with energy below $\\e_m$, we identify the maximum\namplitudes of different types of perturbations that are consistent with\nperturbation-induced energy splittings not exceeding the $\\e_m$ limit. We argue\nthat measurements generating perturbations larger than the threshold amplitudes\nappropriate for $\\e_m$ cannot realize measurement-based braiding in SM-SC\nheterostructures in the quasi-Majorana regime. We find that, if possible at\nall, quantum computation using measurement-based braiding in the quasi-Majorana\nregime would be plagued with errors introduced by the measurement processes\nthemselves, while such errors are significantly less likely in a scheme\ninvolving topological MZMs.",
        "positive": "Phases of the excitonic condensate in two-layer graphene: Two graphene monolayers that are oppositely charged and placed close to each\nother are considered. Taking into account valley and spin degeneracy of\nelectrons we analyze the symmetry of the excitonic insulator states in such a\nsystem and build a phase diagram that takes into account the effect of the\nsymmetry breaking due to the external in-plane magnetic field and the carrier\ndensity imbalance between the layers."
    },
    {
        "anchor": "Electronic Structure Theory of Strained Two-Dimensional Materials with\n  Hexagonal Symmetry: We derive electronic tight-binding Hamiltonians for strained graphene,\nhexagonal boron nitride and transition metal dichalcogenides based on Wannier\ntransformation of {\\it ab initio} density functional theory calculations. Our\nmicroscopic models include strain effects to leading order that respect the\nhexagonal crystal symmetry and local crystal configuration, and are beyond the\ncentral force approximation which assumes only pair-wise distance dependence.\nBased on these models, we also derive and analyze the effective low-energy\nHamiltonians. Our {\\it ab initio} approaches complement the symmetry group\nrepresentation construction for such effective low-energy Hamiltonians and\nprovide the values of the coefficients for each symmetry-allowed term. These\nmodels are relevant for the design of electronic device applications, since\nthey provide the framework for describing the coupling of electrons to other\ndegrees of freedom including phonons, spin and the electromagnetic field. The\nmodels can also serve as the basis for exploring the physics of many-body\nsystems of interesting quantum phases.",
        "positive": "Graphene-based heterojunction between two topological insulators: Quantum Hall (QH) and quantum spin Hall (QSH) phases have very different edge\nstates and, when going from one phase to the other, the direction of one edge\nstate must be reversed. We study this phenomena in graphene in presence of a\nstrong perpendicular magnetic field on top of a spin-orbit (SO) induced QSH\nphase. We show that, below the SO gap, the QSH phase is virtually unaffected by\nthe presence of the magnetic field. Above the SO gap, the QH phase is restored.\nAn electrostatic gate placed on top of the system allows to create a QSH-QH\njunction which is characterized by the existence of a spin-polarized chiral\nstate, propagating along the topological interface. We find that such a setup\nnaturally provides an extremely sensitive spin-polarized current switch."
    },
    {
        "anchor": "Control of the in-plane anisotropy in off-stoichiometric NiMnSb: NiMnSb is a ferromagnetic half-metal which, because of its rich anisotropy\nand very low Gilbert damping, is a promising candidate for applications in\ninformation technologies. We have investigated the in-plane anisotropy\nproperties of thin, MBE-grown NiMnSb films as a function of their Mn\nconcentration. Using ferromagnetic resonance (FMR) to determine the uniaxial\nand four-fold anisotropy fields, 2KU/Ms and 2K1/Ms, we find that a small\nvariation in composition is sufficient to change the film from primarily\nfour-fold to primarily uniaxial behavior, allowing for continuous tuning of the\nanisotropy. This provides valuable flexibility in designing new device\ngeometries.",
        "positive": "Inter-edge strong-to-weak scattering evolution at a constriction in the\n  fractional quantum Hall regime: Gate-voltage control of inter-edge tunneling at a split-gate constriction in\nthe fractional quantum Hall regime is reported. Quantitative agreement with the\nbehavior predicted for out-of-equilibrium quasiparticle transport between\nchiral Luttinger liquids is shown at low temperatures at specific values of the\nbackscattering strength. When the latter is lowered by changing the gate\nvoltage the zero-bias peak of the tunneling conductance evolves into a minimum\nand a non-linear quasihole-like characteristic emerges. Our analysis emphasizes\nthe role of the local filling factor in the split-gate constriction region."
    },
    {
        "anchor": "Anomalous orbital magnetism in Dirac-electron systems: Role of\n  pseudo-spin paramagnetism: The orbital diamagnetic susceptibility is calculated in monolayer and bilayer\ngraphenes with band gap as well as in three-dimensional Dirac systems. It is\ndemonstrated that the pseudo-spin degree of freedom such as valleys produces\nparamagnetic susceptibility in an equal manner as the real spin dominating over\nthe Landau diamagnetism. The pseudo-spin paramagnetism explains the origin of a\nsingular diamagnetism which is present only in the band-gap region and\ndisappears rapidly inside the conduction and valence bands.",
        "positive": "A Multifunctional Sub-10nm Transistor: Nano-electronic integrated circuit technology is exclusively based on MOSFET\ntransistor due to its scalability down to the nanometer range. On the other\nhand, Bipolar Junction Transistor (BJT), which provides unmatched analog\ncharacteristics and frequency response, cannot be scaled to nanometer regime\nwithout the loss of transistor action. Here a versatile nanoscale transistor is\nintroduced that provides identical BJT behavior and expands its capabilities.\nThe new transistor uses CMOS fabrication technology and creates BJT emitter,\nbase, and collector via electric fields. By allowing carrier modulation during\noperation, its current gain can be changed at least by five orders of\nmagnitude. This property introduces novel adaptive, variable gain, and\nprogrammable analog modules into existing electronic circuit design and\nmanufacturing. A NOT gate version of this device with the critical dimension of\n7 nm operates at 730 GHz, and its three-stage ring oscillator exhibits a\nfrequency of 240 GHz. With proper gate biasing, it can also operate as a\nnanoscale MOSFET, easily alleviating short-channel effects."
    },
    {
        "anchor": "Microscopic theory of spin-relaxation of a single Fe adatom coupled to\n  substrate vibrations: Understanding the spin-relaxation mechanism of single adatoms is an essential\nstep towards creating atomic magnetic memory bits or even qubits. Here we\npresent an essentially parameter-free theory by combining \\textit{ab-initio}\nelectronic and vibrational properties with the many-body nature of atomic\nstates. Our calculations account for the millisecond spin lifetime measured\nrecently on Fe adatoms on MgO/Ag(100) and reproduce the dependence on the\nnumber of decoupling layers and the external magnetic field. We show how the\natomic interaction with the environment should be tuned in order to enhance the\nmagnetic stability, and propose a clear fingerprint for experimentally\ndetecting a localized spin-phonon excitation.",
        "positive": "Fully tunable exciton-polaritons emerging from WS$_{2}$ monolayer\n  excitons in an optical lattice at room temperature: Engineering non-linear hybrid light-matter states in tailored optical\nlattices is a central research strategy for the simulation of complex\nHamiltonians. Excitons in atomically thin crystals are an ideal active medium\nfor such purposes, since they couple strongly with light and bear the potential\nto harness giant non-linearities and interactions while presenting a simple\nsample-processing and room temperature operability. We demonstrate lattice\npolaritons, based on an open, high-quality optical cavity, with an imprinted\nphotonic lattice strongly coupled to excitons in a WS$_{2}$ monolayer. We\nexperimentally observe the emergence of the canonical band-structure of\nparticles in a one-dimensional lattice at room temperature, and demonstrate\nfrequency reconfigurability over a spectral window exceeding 12 meV, as well as\nthe systematic variation of the nearest neighbour coupling, reflected by a\ntuneability in the bandwidth of the p-band polaritons by 7 meV. The technology\npresented in this work is a critical demonstration towards reconfigurable\nphotonic emulators operated with non-linear photonic fluids, offering a simple\nexperimental implementation and working at ambient conditions."
    },
    {
        "anchor": "Intervalley electron-hole exchange interaction and impurity-assisted\n  recombination of indirect excitons in WS$_2$ and WSe$_2$ monolayers: The variety of excitonic states in tungsten-based dichalcogenide monolayers\nstems from unique interplay between the spin and valley degrees of freedom. One\nof the exciton species is the indirect exciton (momentum or valley dark), which\nis responsible to a series of resonances when the monolayer is charge neutral.\nWe investigate the short-range electron-hole exchange interaction of the\nindirect exciton, as well as its recombination mechanism mediated by\nimpurities. The analysis provides thorough understanding of the energy and\npolarization of the zero-phonon indirect exciton resonance in the emission\nspectrum.",
        "positive": "Topological superconductivity and anti-Shiba states in disordered chains\n  of magnetic adatoms: Regular arrays of magnetic atoms on a superconductor provide a promising\nplatform for topological superconductivity. In this work we study effects of\ndisorder in these systems, focusing on vacancies realized by missing magnetic\natoms. We develop approaches that allow treatment of ferromagnetic dense chains\nas well as long-range hopping ferromagnetic and helical Shiba chains at\narbitrary subgap energies. Vacancies in magnetic chains play an analogous role\nto magnetic impurities in a clean $s$-wave superconductor. A single vacancy in\na topological chain gives rise to a low-lying \"anti-Shiba\" state below the band\nedge of a regular magnetic chain. Proliferation of the anti-Shiba band formed\nby a finite density of hybridized vacancy states leads to deterioration of the\ntopological phase, which exhibits unusual fragility in a particular parameter\nregion in dilute chains. We also consider local fluctuation in the Shiba\ncoupling and discuss how vacancy states could contribute to experimental\nverification of topological superconductivity."
    },
    {
        "anchor": "Energy polarization and energy pumping in Rice-Mele chains: The one-dimensional Rice-Mele lattice consisting of two-site unit cells\nenables topological charge pumping at low enough temperatures. We show here\nthat energy pumping is feasible in this system. We analyze energy polarization\nusing the second-quantization formalism and connect it to intercell energy\ncurrent by the relevant continuity equation. Following this formulation, we\nnumerically evaluate the energy current pumped in an adiabatic cycle when the\nsystem parameters vary periodically and slowly with time. Unlike the pumped\ncharge, the pumped energy is entirely temperature-independent at half filling.\nThe global Berry phase for all bands and the related topological phase\ntransitions during the pumping cycle account for the energy pumping. The\npresent study paves the way for manipulating energy current without electric\nand thermal biases.",
        "positive": "Dirac electrons in a Kronig-Penney potential: dispersion relation and\n  transmission periodic in the strength of the barriers: The transmission T and conductance G through one or multiple one-dimensional,\ndelta-function barriers of two-dimensional fermions with a linear energy\nspectrum are studied. T and G are periodic functions of the strength P of the\ndelta-function barrier V(x,y) / hbar v_F = P delta(x). The dispersion relation\nof a Kronig-Penney (KP) model of a superlattice is also a periodic function of\nP and causes collimation of an incident electron beam for P = 2 pi n and n\ninteger. For a KP superlattice with alternating sign of the height of the\nbarriers the Dirac point becomes a Dirac line for P = (n + 1/2) pi."
    },
    {
        "anchor": "Transport through a disordered topological-metal strip: Features of a topological phase, and edge states in particular, may be\nobscured by overlapping in energy with a trivial conduction band. The\ntopological nature of such a conductor, however, is revealed in its transport\nproperties, especially in the presence of disorder. In this work, we explore\nthe conductance behavior of such a system with disorder present, and contrast\nit with the quantized conductance in an ideal 2D topological insulator. Our\nanalysis relies on numerics on a lattice system and analytics on a simple toy\nmodel. Interestingly, we find that as disorder is increased from zero, the edge\nconductivity initially falls from its quantized value; yet as disorder\ncontinues to increase, the conductivity recovers, and saturates at a value\nslightly below the quantized value of the clean system. We discuss how this\neffect can be understood from the tendency of the bulk states to localize,\nwhile the edge states remain delocalized.",
        "positive": "Magnetic breakdown of cyclotron orbits in systems with Rashba and\n  Dresselhaus spin-orbit coupling: We study the effect of the interplay between the Rashba and the Dresselhaus\nspin-orbit couplings on the transverse electron focusing in two-dimensional\nelectron gases. Depending on their relative magnitude, the presence of both\ncouplings can result in the splitting of the first focusing peak into two or\nthree. This splitting has information about the relative value of spin-orbit\ncouplings and therefore about the shape of the Fermi surface. More interesting,\nthe presence of the third peak is directly related to the tunneling probability\n(\"magnetic breakdown\") between orbits corresponding to the different sheets of\nthe Fermi surface. In addition, destructive interference effects between paths\nthat involve tunneling and those that do not can be observed in the second\nfocusing condition. Such electron paths (orbits) could be experimentally\ndetected using current techniques for imaging the electron flow opening the\npossibility to directly observe and characterize the magnetic breakdown effect\nin this system."
    },
    {
        "anchor": "The Ferris ferromagnetic resonance technique: principles and\n  applications: Measurements of ferromagnetic resonance (FMR) are pivotal to modern magnetism\nand spintronics. Recently, we reported on the Ferris FMR technique, which\nrelies on large-amplitude modulation of the externally applied magnetic field.\nIt was shown to benefit from high sensitivity while being broadband. The Ferris\nFMR also expanded the resonance linewidth such that the sensitivity to spin\ncurrents was enhanced as well. Eventually, the spin Hall angle ({\\theta}_SH)\nwas measurable even in wafer-level measurements that require low current\ndensities to reduce the Joule heating. Despite the various advantages, analysis\nof the Ferris FMR response is limited to numerical modeling where the linewidth\ndepends on multiple factors such as the field modulation profile and the\nmagnetization saturation. Here, we describe in detail the basic principles of\noperation of the Ferris FMR and discuss its applicability and engineering\nconsiderations. We demonstrated these principles in a measurement of the\norbital Hall effect taking place in Cu, using an Au layer as the orbital to\nspin current converter. This illustrates the potential of the Ferris FMR for\nthe future development of spintronics technology.",
        "positive": "Exponential behavior of the interlayer exchange coupling across\n  non-magnetic metallic superlattices: It is shown that the coupling between magnetic layers separated by\nnon-magnetic metallic superlattices can decay exponentially as a function of\nthe spacer thickness $N$, as opposed to the usual $N^{-2}$ decay. This effect\nis due to the lack of constructive contributions to the coupling from extended\nstates across the spacer. The exponential behavior is obtained by properly\nchoosing the distinct metals and the superlattice unit cell composition."
    },
    {
        "anchor": "Inhomogeneous soliton ratchets under two ac forces: We extend our previous work on soliton ratchet devices [L. Morales-Molina et\nal., Eur. Phys. J. B 37, 79 (2004)] to consider the joint effect of two ac\nforces including non-harmonic drivings, as proposed for particle ratchets by\nSavele'v et al. [Europhys. Lett. 67}, 179 (2004); Phys. Rev. E {\\bf 70} 066109\n(2004)]. Current reversals due to the interplay between the phases, frequencies\nand amplitudes of the harmonics are obtained. An analysis of the effect of the\ndamping coefficient on the dynamics is presented. We show that solitons give\nrise to non-trivial differences in the phenomenology reported for particle\nsystems that arise from their extended character. A comparison with soliton\nratchets in homogeneous systems with biharmonic forces is also presented. This\nratchet device may be an ideal candidate for Josephson junction ratchets with\nintrinsic large damping.",
        "positive": "Spontaneous imbibition in a slit pore: a lattice-gas dynamic mean field\n  study: We present a theoretical study of spontaneous imbibition in a slit pore using\na lattice-gas model and a dynamic mean-field theory. Emphasis is put on the\ninfluence of the precursor films on the speed of the imbibition front due to\nliquid mass conservation. This work is dedicated to Bob Evans for his 65th\nbirthday in recognition of his seminal contributions to the theory of fluids in\nconfining geometries."
    },
    {
        "anchor": "The unconventional two-parameter quantum valley pumping in graphene with\n  a topological line defect: Based on the Keldysh Green's function method, we report an unconventional\ntwo-parameter quantum pumping in graphene with a line defect. It is found that\ndifferent from the conventional sinusoidal relation, the pumped current in this\ndevice is cosinusoid dependence on the phase difference between the two pumping\npotentials, which adopts its positive/nagative maximum value at while tends to\nzero at . This phenomenon is related to the peculiar valley tunneling\ncharacteristics across the line defects and the exchange of valley indices on\nboth sides of the line defect. Moreover, the pumped currents from the two\nvalleys will flow in opposite directions along the line defect, indicating that\nthe controllable valley current can be pumped out in the line defect without\nthe application of strain field in graphene.",
        "positive": "Neuromorphic Few-Shot Learning: Generalization in Multilayer Physical\n  Neural Networks: Neuromorphic computing leverages the complex dynamics of physical systems for\ncomputation. The field has recently undergone an explosion in the range and\nsophistication of implementations, with rapidly improving performance.\nNeuromorphic schemes typically employ a single physical system, limiting the\ndimensionality and range of available dynamics - restricting strong performance\nto a few specific tasks. This is a critical roadblock facing the field,\ninhibiting the power and versatility of neuromorphic schemes.\n  Here, we present a solution. We engineer a diverse suite of nanomagnetic\narrays and show how tuning microstate space and geometry enables a broad range\nof dynamics and computing performance. We interconnect arrays in parallel,\nseries and multilayered neural network architectures, where each network node\nis a distinct physical system. This networked approach grants extremely high\ndimensionality and enriched dynamics enabling meta-learning to be implemented\non small training sets and exhibiting strong performance across a broad\ntaskset. We showcase network performance via few-shot learning, rapidly\nadapting on-the-fly to previously unseen tasks."
    },
    {
        "anchor": "Thermal broadening of the power spectra of laser-trapped particles in\n  vacuum: We show that at low pressures the spectral widths of the power spectra of\nlaser-trapped particles are nearly independent from pressures and, due to the\nnonlinearities of the trap, reflect the thermal distribution of particles. In\nthe experiments with nanoparticles trapped in an optical lattice, we identify\ntwo distinct features of the widths. First, the widths along an optical lattice\nare much broader than those in the other directions. Second, the spectral\nwidths are narrower for larger nanoparticles. We develop a theory of thermal\nbroadening and show that the spectral widths normalized by the frequencies of\nthe center-of-mass motion directly reveal the ratio of the thermal energy to\nthe trap depth. The presented model provides a good understanding of the\nobserved features. Our model holds also for smaller particles such as atoms and\nmolecules and can be readily extended to the general case with a single-beam\noptical trap.",
        "positive": "Two-instanton approximation to the Coulomb blockade problem: We develop the two-instanton approximation to the current-voltage\ncharacteristic of a single electron transistor within the\nAmbegaokar-Eckern-Sch\\\"on model. We determine the temperature and gate voltage\ndependence of the Coulomb blockade oscillations of the conductance and the\neffective charge. We find that a small (in comparison with the charging energy)\nbias voltage leads to significant suppression of the Coulomb blockade\noscillations and to appearance of the bias-dependent phase shift."
    },
    {
        "anchor": "Observing photo-induced chiral edge states of graphene nanoribbons in\n  pump-probe spectroscopies: Photo-induced edge states in low dimensional materials have attracted\nconsiderable attention due to the tunability of topological properties and\ndispersion. Specifically, graphene nanoribbons have been predicted to host\nchiral edge modes upon irradiation with circularly polarized light. Here, we\npresent numerical calculations of time-resolved angle resolved photoemission\nspectroscopy (trARPES) and time-resolved resonant inelastic x-ray scattering\n(trRIXS) of a graphene nanoribbon. We characterize pump-probe spectroscopic\nsignatures of photo-induced edge states, illustrate the origin of distinct\nspectral features that arise from Floquet topological edge modes, and\ninvestigate the roles of incoming photon energies and finite core-hole lifetime\nin RIXS. With momentum, energy, and time resolution, pump-probe spectroscopies\ncan play an important role in understanding the behavior of photo-induced\ntopological states of matter.",
        "positive": "Spin-filter effect at the interface of magnetic/non-magnetic\n  homojunctions in Li doped ZnO nanostructures: After more than a decade of extensive research on the magnetic order\ntriggered by lattice defects in a wide range of nominally non-magnetic\nmaterials, we report its application in a spintronic device. This device is\nbased on a spin-filter phenomenon we discovered at the interfaces between\ndefect-induced magnetic and non-magnetic regions, produced at the surface of a\nLi doped ZnO microwire by low-energy proton implantation. Positive\nmagnetoresistance is observed at 300~K and scales with the number of interfaces\nintroduced along the wire."
    },
    {
        "anchor": "Spin filling of a quantum dot derived from excited-state spectroscopy: We study the spin filling of a semiconductor quantum dot using excited-state\nspectroscopy in a strong magnetic field. The field is oriented in the plane of\nthe two-dimensional electron gas in which the dot is electrostatically defined.\nBy combining the observation of Zeeman splitting with our knowledge of the\nabsolute number of electrons, we are able to determine the ground state spin\nconfiguration for one to five electrons occupying the dot. For four electrons,\nwe find a ground state spin configuration with total spin S=1, in agreement\nwith Hund's first rule. The electron g-factor is observed to be independent of\nmagnetic field and electron number.",
        "positive": "A Universal Interacting Crossover Regime in Two-Dimensional Quantum Dots: Interacting electrons in quantum dots with large Thouless number $g$ in the\nthree classical random matrix symmetry classes are well-understood. When a\nspecific type of spin-orbit coupling known to be dominant in two dimensional\nsemiconductor quantum dots is introduced, we show that a new interacting\nquantum critical crossover energy scale emerges and low-energy quasiparticles\ngenerically have a decay width proportional to their energy. The low-energy\nphysics of this system is an example of a universal interacting crossover\nregime."
    },
    {
        "anchor": "Classification of time-reversal-invariant crystals with gauge structures: A peculiar feature of quantum states is that they may embody so-called\nprojective representations of symmetries rather than ordinary representations.\nProjective representations of space groups-the defining symmetry of\ncrystals-remain largely unexplored. Despite recent advances in artificial\ncrystals, whose intrinsic gauge structures necessarily require a projective\ndescription, a unified theory is yet to be established. Here, we establish such\na unified theory by exhaustively classifying and representing all 458\nprojective symmetry algebras of time-reversal-invariant crystals from 17\nwallpaper groups in two dimensions-189 of which are algebraically\nnon-equivalent. We discover three physical signatures resulting from projective\nsymmetry algebras, including the shift of high-symmetry momenta, an enforced\nnontrivial Zak phase, and a spinless eight-fold nodal point. Our work offers a\ntheoretical foundation for the field of artificial crystals and opens the door\nto a wealth of topological states and phenomena beyond the existing paradigms.",
        "positive": "A Possible Nanometer-scale Computing Device Based on an Adding Cellular\n  Automaton: We present a simple one-dimensional Cellular Automaton (CA) which has the\nproperty that an initial state composed of two binary numbers evolves quickly\ninto a final state which is their sum. We call this CA the Adding Cellular\nAutomaton (ACA). The ACA requires only 2N two-state cells in order to add any\ntwo N-1 bit binary numbers. The ACA could be directly realized as a wireless\nnanometer-scale computing device - a possible implementation using coupled\nquantum dots is outlined."
    },
    {
        "anchor": "Interface moment dynamics and its contribution to spin-transfer torque\n  switching process in magnetic tunnel junctions: A practical problem for memory applications involving perpendicularly\nmagnetized magnetic tunnel junctions is the reliability of switching\ncharacteristics at high-bias voltage. Often it has been observed that at\nhigh-bias, additional error processes are present that cause a decrease in\nswitching probability upon further increase of bias voltage. We identify the\nmain cause of such error-rise process through examination of switching\nstatistics as a function of bias voltage and applied field, and the junction\nswitching dynamics in real time. These experiments show a coincidental onset of\nerror-rise and the presence of a new low-frequency microwave emission well\nbelow that dictated by the anisotropy field. We show that in a few-macrospin\ncoupled numerical model, this is consistent with an interface region with\nconcentrated perpendicular anisotropy, and where the magnetic moment has\nlimited exchange coupling to the rest of the layers. These results point to the\nimportant role high-frequency interface magnetic moment dynamics play in\ndetermining the switching characteristics of these tunnel junction devices.",
        "positive": "Room-temperature single photon emission from micron-long air-suspended\n  carbon nanotubes: Statistics of photons emitted by mobile excitons in individual carbon\nnanotubes are investigated. Photoluminescence spectroscopy is used to identify\nthe chiralities and suspended lengths of air-suspended nanotubes, and photon\ncorrelation measurements are performed at room temperature on\ntelecommunication-wavelength nanotube emission with a Hanbury-Brown-Twiss\nsetup. We obtain zero-delay second-order correlation $g^{(2)}(0)$ less than\n0.5, indicating single photon generation. Excitation power dependence of the\nphoton antibunching characteristics is examined for nanotubes with various\nchiralities and suspended lengths, where we find that the minimum value of\n$g^{(2)}(0)$ is obtained at the lowest power. The influence of exciton\ndiffusion and end quenching is studied by Monte Carlo simulations, and we\nderive an analytical expression for the minimum value of $g^{(2)}(0)$. Our\nresults indicate that mobile excitons in micron-long nanotubes can in principle\nproduce high-purity single photons, leading to new design strategies for\nquantum photon sources."
    },
    {
        "anchor": "Excitation of spin density and current by coherent light pulses in QWs: We study the orbital and spin dynamics of charge carriers induced by\nnon-overlapping linearly polarized light pulses in semiconductor quantum wells\n(QWs). It is shown that such an optical excitation with coherent pulses leads\nto a spin orientation of photocarriers and an electric current. The effects are\ncaused by the interference of optical transitions driven by individual pulses.\nThe distribution of carriers in the spin and momentum spaces depends on the QW\ncrystallographic orientation and can be efficiently controlled by the pulse\npolarizations, time delay and phase shift between the pulses, as well as an\nexternal magnetic field.",
        "positive": "Axial vs. Radial Junction Nanowire Solar Cell: Both axial and radial junction nanowire solar cells have their challenges and\nadvantages. However, so far, there is no review that explicitly provides a\ndetailed comparative analysis of both axial and radial junction solar cells.\nThis article reviews some of the recent results on axial and radial junction\nnanowire solar cells with an attempt to perform a comparative study between the\noptical and device behavior of these cells. In particular, we start by\nreviewing different results on how the absorption can be tuned in axial and\nradial junction solar cells. We also discuss results on some of the critical\ndevice concepts that are required to achieve high efficiency in axial and\nradial junction solar cells. We include a section on new device concepts that\ncan be realized in nanowire structures. Finally, we conclude this review by\ndiscussing a few of the standing challenges of nanowire solar cells."
    },
    {
        "anchor": "Fractional topological excitations and quantum phase transition in a\n  bilayer 2DEG adjacent to a superconductor film: We study a bilayer two-dimension-electron-gas (2DEG) adjacent to a type-II\nsuperconductor thin film with a pinned vortex lattice. We find that with\nincreasing interlayer tunneling, the system of half filling presents three\nphases: gapped phase-I (topological insulator), gapless critical phase-II\n(metal), and gapped phase-III (band insulator). The Hall conductance for\nphase-I/III is 2/0 $e^{2}/h$, and has non-quantized values in phase-II. The\nexcitation (response to topological defect, a local vortex defect) in these\nthree phases shows different behaviors due to the topological property of the\nsystem, including fractional charge $e/2$ for each layer in phase-I. While in\nthe case of quarter filling, the system undergoes a quantum phase transition\nfrom metallic phase to topological insulator phase (with excitation of\nfractional charge $e/4$).",
        "positive": "Self-consistent theory of molecular switching: We study the model of a molecular switch comprised of a molecule with a soft\nvibrational degree of freedom coupled to metallic leads. In the presence of\nstrong electron-ion interaction, different charge states of the molecule\ncorrespond to substantially different ionic configurations, which can lead to\nvery slow switching between energetically close configurations (Franck-Condon\nblockade). Application of transport voltage, however, can drive the molecule\nfar out of thermal equilibrium and thus dramatically accelerate the switching.\nThe tunneling electrons play the role of a heat bath with an effective\ntemperature dependent on the applied transport voltage. Including the\ntransport-induced \"heating\" selfconsistently, we determine the stationary\ncurrent-voltage characteristics of the device, and the switching dynamics for\nsymmetric and asymmetric devices. We also study the effects of an extra\ndissipative environment and demonstrate that it can lead to enhanced\nnon-linearities in the transport properties of the device and dramatically\nsuppress the switching dynamics."
    },
    {
        "anchor": "Spin Sensitive Transmission Through Helical Potentials: We calculate the transmission coefficient for electrons passing through the\nhelically shaped potential barrier, which can be, for example, produced by DNA\nmolecules.",
        "positive": "Magneto-quantum oscillations of the conductance of a tunnel\n  point-contact in the presence of a single defect: The influence of a quantizing magnetic field $H$ to the conductance of a\ntunnel point contact in the presence of the single defect has been considered.\nWe demonstrate that the conductance exhibits specific magneto-quantum\noscillations, the amplitude and period of which depend on the distance between\nthe contact and the defect. We show that a non-monotonic dependence of the\npoint-contact conductance results from a superposition of two types of\noscillations: A short period oscillation arising from electron focusing by the\nfield $H$ and a long period oscillation of Aharonov-Bohm-type originated from\nthe magnetic flux passing through the closed trajectories of electrons moving\nfrom the contact to the defect and returning back to the contact."
    },
    {
        "anchor": "Automated tuning of double quantum dots into specific charge states\n  using neural networks: While quantum dots are at the forefront of quantum device technology, tuning\nmulti-dot systems requires a lengthy experimental process as multiple\nparameters need to be accurately controlled. This process becomes increasingly\ntime-consuming and difficult to perform manually as the devices become more\ncomplex and the number of tuning parameters grows. In this work, we present a\ncrucial step towards automated tuning of quantum dot qubits. We introduce an\nalgorithm driven by machine learning that uses a small number of coarse-grained\nmeasurements as its input and tunes the quantum dot system into a pre-selected\ncharge state. We train and test our algorithm on a GaAs double quantum dot\ndevice and we consistently arrive at the desired state or its immediate\nneighborhood.",
        "positive": "Moir\u00e9 Semiconductors on Twisted Bilayer Dice Lattice: We propose an effective lattice model for the Moir\\'e structure of twisted\nbilayer dice lattice. We find that there are flat bands near zero energy level\nat any twist angle besides the magic ones. The flat bands contain both bands\nwith zero Chern number which are originated from the destructive interference\nof the dice lattice and the topological non-trivial ones at the magic angle.\nThe existence of the flat bands can be detected from the peak-splitting fine\nstructure of the optical conductance at all angles, while the transition peaks\ndo not split and only occur at magic angles in twisted bilayer graphene."
    },
    {
        "anchor": "Emergent phases in graphene flat bands: Electronic correlations in two-dimensional materials play a crucial role in\nstabilising emergent phases of matter. The realisation of correlation-driven\nphenomena in graphene has remained a longstanding goal, primarily due to the\nabsence of strong electron-electron interactions within its low-energy bands.\nIn this context, magic-angle twisted bilayer graphene has recently emerged as a\nnovel platform featuring correlated phases favoured by the low-energy flat\nbands of the underlying moir\\'e superlattice. Notably, the observation of\ncorrelated insulators and superconductivity has garnered significant attention,\nleading to substantial progress in theoretical and experimental studies aiming\nto elucidate the origin and interplay between these two phases. A wealth of\ncorrelated phases with unprecedented tunability was discovered subsequently,\nincluding orbital ferromagnetism, Chern insulators, strange metallicity,\ndensity waves, and nematicity. However, a comprehensive understanding of these\nclosely competing phases remains elusive. The ability to controllably twist and\nstack multiple graphene layers has enabled the creation of a whole new family\nof moir\\'e superlattices with myriad properties being discovered at a fast\npace. Here, we review the progress and development achieved so far,\nencompassing the rich phase diagrams offered by these graphene-based moir\\'e\nsystems. Additionally, we discuss multiple phases recently observed in\nnon-moir\\'e multilayer graphene systems. Finally, we outline future\nopportunities and challenges for the exploration of hidden phases in this new\ngeneration of moir\\'e materials.",
        "positive": "Teraherz photomixing using plasma resonances in double-graphene layer\n  structures: We propose the concept of terahertz (THz) photomixing enabled by the\ninterband electron transitions due to the absorption of modulated optical\nradiation in double-graphene layer (double-GL) structures and the resonant\nexcitation of plasma oscillations. Using the developed double-GL photomixer\n(DG-PM) model, we describe its operation and calculate the device\ncharacteristics. The output power of the THz radiation exhibits sharp resonant\npeaks at the plasmonic resonant frequencies. The peak powers markedly exceed\nthe output powers at relatively low frequencies. Due to relatively high quantum\nefficiency of optical absorption in GLs and short inter-GL transit time, the\nproposed DG-PM operating in the resonant plasma oscillation regime can surpass\nthe photomixers based on the standard heterostructures ."
    },
    {
        "anchor": "Weak antilocalization in high mobility Ga(x)In(1-x)As/InP\n  two-dimensional electron gases with strong spin-orbit coupling: We have studied the spin-orbit interaction in a high mobility two-dimensional\nelectron gas in a GaInAs/InP heterostructure as a function of an applied gate\nvoltage as well as a function of temperature. Highly sensitive magnetotransport\nmeasurements of weak antilocalization as well as measurements of Shubnikov--de\nHaas oscillations were performed in a wide range of electron sheet\nconcentrations. In our samples the electron transport takes place in the strong\nspin precession regime in the whole range of applied gate voltages, which is\ncharacterized by the spin precession length being shorter than the elastic mean\nfree path. The magnitude of the Rashba spin-orbit coupling parameter was\ndetermined by fitting the experimental curves by a simulated quantum\nconductance correction according to a model proposed recently by Golub [Phys.\nRev. B 71, 235310 (2005)]. A comparison of the Rashba coupling parameter\nextracted using this model with the values estimated from the analysis of the\nbeating pattern in the Shubnikov--de Haas oscillations showed a good agreement.",
        "positive": "Electron dynamics in intentionally disordered semiconductor\n  superlattices: We study the dynamical behavior of disordered quantum-well-based\nsemiconductor superlattices where the disorder is intentional and short-range\ncorrelated. We show that, whereas the transmission time of a particle grows\nexponentially with the number of wells in an usual disordered superlattice for\nany value of the incident particle energy, for specific values of the incident\nenergy this time increases linearly when correlated disorder is included. As\nexpected, those values of the energy coincide with a narrow subband of extended\nstates predicted by the static calculations of Dom\\'{\\i}nguez-Adame {\\em et\nal.} [Phys. Rev. B {\\bf 51}, 14 ,359 (1994)]; such states are seen in our\ndynamical results to exhibit a ballistic regime, very close to the WKB\napproximation of a perfect superlattice. Fourier transform of the output signal\nfor an incident Gaussian wave packet reveals a dramatic filtering of the\noriginal signal, which makes us confident that devices based on this property\nmay be designed and used for nanotechnological applications. This is more so in\nview of the possibility of controllingthe outp ut band using a dc electric\nfield, which we also discuss. In the conclusion we summarize our results and\npresent an outlook for future developments arising from this work."
    },
    {
        "anchor": "Topological superconductivity and fractional Josephson effect in\n  quasi-one dimensional wires on a plane: A time-reversal invariant topological superconductivity is suggested to be\nrealized in a quasi-one dimensional structure on a plane, which is fabricated\nby filling the superconducting materials into the periodic channel of\ndielectric matrices like zeolite and asbestos under high pressure. The\ntopological superconducting phase sets up in the presence of large spin-orbit\ninteractions when intra-wire s-wave and inter-wire d-wave pairings take place.\nKramers pairs of Majorana bound states emerge at the edges of each wire. We\nanalyze effects of Zeeman magnetic field on Majorana zero-energy states.\nIn-plane magnetic field was shown to make asymmetric the energy dispersion,\nnevertheless Majorana fermions survive due to protection of a particle-hole\nsymmetry. Tunneling of Majorana quasi-particle from the end of one wire to the\nnearest-neighboring one yields edge fractional Josephson current with\n$4\\pi$-periodicity.",
        "positive": "Long-lived Andreev states as evidence for protected hinge modes in a\n  bismuth nanoring Josephson junction: Second-order topological insulators are characterized by helical,\nnon-spin-degenerate, one-dimensional states running along opposite crystal\nhinges, with no backscattering. Injecting superconducting pairs therefore\nentails splitting Cooper pairs into two families of helical Andreev states of\nopposite helicity, one at each hinge. Here we provide evidence for such\nseparation via the measurement and analysis of switching supercurrent\nstatistics of a crystalline nanoring of bismuth. Using a phenomenological model\nof two helical Andreev hinge modes, we find that pairs relax at a rate\ncomparable to individual quasiparticles, in contrast with the much faster pair\nrelaxation of non-topological systems. This constitutes a unique tell-tale sign\nof the spatial separation of topological helical hinges."
    },
    {
        "anchor": "Analytical model and dynamical phase-field simulation of terahertz\n  transmission across ferroelectrics: We theoretically investigate the steady-state transmission of continuous\nterahertz (THz) wave across a freestanding ferroelectric slab. Based on the\nLandau-Ginzburg-Devonshire theory of ferroelectrics and the coupled equations\nof motion for polarization and electromagnetic (EM) waves, we derive the\nanalytical expressions of the frequency- and thickness-dependent dielectric\nsusceptibility and transmission coefficient at the thin slab limit in the\nharmonic excitation regime. When the slab thickness is much smaller than the\nTHz wavelength in the ferroelectric, the analytical predictions agree well with\nthe numerical simulations from a dynamical phase-field model that incorporates\nthe coupled dynamics of strain, polarization, and EM wave in multiphase\nsystems. At larger thicknesses, the transmission is mainly determined by the\nfrequency-dependent attenuation of THz waves in the ferroelectric and the\nformation of a standing polarization/THz wave. Our results advance the\nunderstanding of the interaction between THz wave and ferroelectrics and\nsuggest the potential of exploiting ferroelectrics to achieve\nlow-heat-dissipation, nonvolatile voltage modulation of THz transmission for\nhigh-data-rate wireless communication.",
        "positive": "Current and noise in a model of an AC-STM molecule-metal junction: The transport properties of a simple model for a finite level structure (a\nmolecule or a dot) connected to metal electrodes in an alternating current\nscanning tunneling microscope (AC-STM) configuration is studied. The finite\nlevel structure is assumed to have strong binding properties with the metallic\nsubstrate, and the bias between the STM tip and the hybrid metal-molecule\ninterface has both an AC and a DC component. The finite frequency current\nresponse and the zero frequency photo-assisted shot noise are computed using\nthe Keldysh technique, and examples for a single site molecule (a quantum dot)\nand for a two-site molecule are examined. The model may be useful for the\ninterpretation of recent experiments using an AC-STM for the study of both\nconducting and insulating surfaces, where the third harmonic component of the\ncurrent is measured. The zero frequency photo-assisted shot noise serves as a\nuseful diagnosis for analyzing the energy level structure of the molecule. The\npresent work motivates the need for further analysis of current fluctuations in\nelectronic molecular transport."
    },
    {
        "anchor": "Self-ordered nanostructures on patterned substrates: Experiment and\n  theory of metalorganic vapor-phase epitaxy of V-groove quantum wires and\n  pyramidal quantum dots: The formation of nanostructures during metalorganic vapor-phase epitaxy on\npatterned (001)/(111)B GaAs substrates is reviewed. The focus of this review is\non the seminal experiments that revealed the key kinetic processes during\nnanostructure formation and the theory and modelling that explained the\nphenomenology in successively greater detail. Experiments have demonstrated\nthat V-groove quantum wires and pyramidal quantum dots result from\nself-limiting concentration profiles that develop at the bottom of V-grooves\nand inverted pyramids, respectively. In the 1950s, long before the practical\nimportance of patterned substrates became evident, the mechanisms of\ncapillarity during the equilibration of non-planar surfaces were identified and\ncharacterized. This was followed, from the late 1980s by the identification of\ngrowth rate anisotropies (i.e. differential growth rates of crystallographic\nfacets) and precursor decomposition anisotropies, with parallel developments in\nthe fabrication of V-groove quantum wires and pyramidal quantum dots. The\nmodelling of these growth processes began at the scale of facets and culminated\nin systems of coupled reaction-diffusion equations, one for each\ncrystallographic facet that defines the pattern, which takes account of the\ndecomposition and surface diffusion kinetics of the group-III precursors and\nthe subsequent surface diffusion and incorporation of the group-III atoms\nreleased by these precursors. Solutions of the equations with optimized\nparameters produced concentration profiles that provided a quantitative\ninterpretation of the time-, temperature-, and alloy-concentration dependence\nof the self-ordering process seen in experiments.",
        "positive": "Green-function method for calculation of adsorption of organic molecules\n  on noble metal nanoparticles: A numerical method for calculation electronic structure of a nanosystem\ncomposed of a pseudoisocyanine (PIC) molecule assembled on a silver\nnanoparticle is developed. The electronic structure of the silver nanoparticle\ncontaining 125 atoms is calculated within the local density version of the\ndensity functional method. A model of an Ag atom embedded in the center of a\nspherical jellium cluster is used. The host electron Green function is\ncalculated by means of the spherically symmetric expansion. The principal\ntheoretical tool is the scattering theory using the Green function method. The\nmolecule -- silver nanoparticle interaction is studied using the approach\nsimilar to that of the Anderson model for transition metal impurities in\nsolids. Localized levels are shown to split off from the top of the band of the\nnanosystem. The electronic structure calculations yield information on the\ncharacter of chemical bonding in the PIC molecule --- silver particle\nnanosystem."
    },
    {
        "anchor": "Quantum coherence and its dephasing in the giant spin Hall effect and\n  nonlocal voltage generated by magnetotransport through multiterminal graphene\n  bars: Motivated by the recent experimental observation [D. A. Abanin et al.,\nScience 323, 328 (2011)] of nonlocality in magnetotransport near the Dirac\npoint in six-terminal graphene Hall bars, for a wide range of temperatures and\nmagnetic fields, we develop a nonequilibrium Green function (NEGF) theory of\nthis phenomenon. In the phase-coherent regime and strong magnetic field, we\nfind large spin Hall (SH) conductance in four-terminal bridges, where the SH\ncurrent is pure only at the Dirac point (DP), as well as the nonlocal voltage\nat a remote location in six-terminal bars where the direct and inverse SH\neffect operate at the same time. The \"momentum-relaxing\" dephasing reduces\ntheir values at the DP by two orders of magnitude while concurrently washing\nout any features away from the DP. Our theory is based on the Meir-Wingreen\nformula with dephasing introduced via phenomenological many-body self-energies,\nwhich is then linearized for multiterminal geometries to extract currents and\nvoltages.",
        "positive": "Generation of high-frequency radiation in semiconductor superlattices\n  with suppressed space-charge instabilities: We theoretically investigated the scheme allowing to avoid destructive\nspace-charge instabilities and to obtain a strong gain at microwave and THz\nfrequencies in semiconductor superlattice devices. Superlattice is subjected to\na microwave field and a generation is achieved at some odd harmonics of the\npump frequency. Gain arises because of parametric amplification seeded by\nharmonic generation. Negative differential conductance (NDC) is not a necessary\ncondition for the generation. For the mode of operation with NDC, a limited\nspace-charge accumulation does not sufficiently reduce the gain."
    },
    {
        "anchor": "Low-Energy Electron Microscopy contrast of stacking boundaries:\n  comparing twisted few-layer graphene and strained epitaxial graphene on\n  silicon carbide: Stacking domain boundaries occur in Van der Waals heterostacks whenever there\nis a twist angle or lattice mismatch between subsequent layers. Not only can\nthese domain boundaries host topological edge states, imaging them has been\ninstrumental to determine local variations in twisted bilayer graphene. Here,\nwe analyse the mechanisms causing stacking domain boundary contrast in Bright\nField Low-Energy Electron Microscopy (BF-LEEM) for both graphene on SiC, where\ndomain boundaries are caused by strain and for twisted few layer graphene. We\nshow that when domain boundaries are between the top two graphene layers,\nBF-LEEM contrast is observed due to amplitude contrast and corresponds well to\ncalculations of the contrast based purely on the local stacking in the domain\nboundary. Conversely, for deeper-lying domain boundaries, amplitude contrast\nonly provides a weak distinction between the inequivalent stackings in the\ndomains themselves. However, for small domains phase contrast, where electrons\nfrom different parts of the unit cell interfere causes a very strong contrast.\nWe derive a general rule-of-thumb of expected BF-LEEM contrast for domain\nboundaries in Van der Waals materials.",
        "positive": "Band structure of magnonic crystals with defects: Brillouin spectroscopy\n  and micromagnetic simulations: Using Brillouin spectroscopy, the first observation has been made of the band\nstructures of nanostructured defect magnonic crystals. The samples are\notherwise one-dimensional periodic arrays of equal-width Ni80Fe20 and cobalt\nnanostripes, where the defects are stripes of a different width. A\ndispersionless defect branch emerges within the bandgap with a frequency\ntunable by varying the defect stripe width, while the other branches observed\nare similar to those of a defect-free crystal. Micromagnetic and finite-element\nsimulations performed unveil additional tiny bandgaps and the\nfrequency-dependent localization of the defect mode in the vicinity of the\ndefects."
    },
    {
        "anchor": "Quantum Hall $p-n$ Junction Dartboards Using Graphene Annuli: The use of multiple current terminals on millimeter-scale graphene $p-n$\njunction devices fabricated with Corbino geometries, or quantum Hall resistance\ndartboards, have enabled the measurement of several fractional multiples of the\nquantized Hall resistance at the $\\nu=2$ plateau ($R_H\\approx 12906 {\\Omega}$).\nExperimentally obtained values agreed with corresponding numerical simulations\nperformed with the LTspice circuit simulator. More complicated designs of the\nquantum Hall resistance dartboard were simulated to establish the potential\nparameter space within which these Corbino-type devices could output\nresistance. Most importantly, these measurements support simpler processes of\nultraviolet lithography as a more efficient means of scaling up graphene-based\ndevice sizes while maintaining sufficiently narrow junctions.",
        "positive": "Simulating and Detecting the Quantum Spin Hall Effect in Kagom\u00e9\n  Optical Lattice: We propose a model which includes a nearest-neighbor intrinsic spin-orbit\ncoupling and a dimer Hamiltonian in the Kagom\\'{e} lattice and promises to host\nthe transition from the quantum spin Hall insulator to the normal insulator. In\naddition, we design an experimental scheme to simulate and detect this\ntransition in the ultracold atom system. The lattice intrinsic spin-orbit\ncoupling is generated via the laser-induced-gauge-field method. Furthermore, we\nestablish the connection between the spin Chern number and the spin-atomic\ndensity which enables us to detect the topological quantum spin Hall insulator\ndirectly by the standard density-profile technique used in the atomic systems."
    },
    {
        "anchor": "Quantum conductivity corrections in two dimensional long-range\n  disordered systems with strong spin-orbit splitting of electron spectrum: We study quantum corrections to conductivity in a 2D system with a smooth\nrandom potential and strong spin-orbit splitting of the spectrum. We show that\nthe interference correction is positive and down to the very low temperature\ncan exceed the negative correction related to electron-electron interactions.\nWe discuss this result in the context of the problem of the metal-insulator\ntransition in Si-MOSFET structures.",
        "positive": "Polarization dependent light-matter coupling and highly\n  indistinguishable resonance fluorescence photons from quantum dot-micropillar\n  cavities with elliptical cross-section: We study the optical properties of coupled quantum dot-microcavity systems\nwith elliptical cross section. First, we develop an analytic model that\ndescribes the spectrum of the cavity modes that are split due to the reduced\nsymmetry of the resonator. By coupling the QD emission to the polarized\nfundamental cavity modes, we observe the vectorial nature of the Purcell\nenhancement, which depends on the intrinsic polarization of the quantum dot and\nits relative alignment with respect to the cavity axis. The variable\ninteraction strength of the QD with the polarized cavity modes leads to the\nobservation of strong and weak coupling. Finally, we demonstrate the capability\nof elliptical micropillars to emit single and highly indistinguishable photons\n(visibility over 93 \\%)."
    },
    {
        "anchor": "Flat bands, strains, and charge distribution in twisted-bilayer hBN: We study the effect of twisting on bilayer graphene. The effect of lattice\nrelaxation is included; we look at the electronic structure, piezo-electric\ncharges and spontaneous polarisation. We show that the electronic structure\nwithout lattice relaxation shows a set of extremely flat in-gap states similar\nto Landau-levels, where the spacing scales with twist angle. With lattice\nrelaxation we still have flat bands, but now the spectrum becomes independent\nof twist angle for sufficiently small angles. We describe in detail the nature\nof the bands, and study appropriate continuum models, at the same time\nexplaining the spectrum We find that even though the spectra for both parallel\nan anti-parallel alignment are very similar, the spontaneous polarisation\neffects only occur for parallel alignment. We argue that this suggests a large\ninterlayer hopping between boron and nitrogen.",
        "positive": "Two impurity Kondo problem under Aharonov--Bohm and Aharonov--Casher\n  Effects: We investigate electron transport under the two impurity Kondo problem with\nthe Aharonov--Bohm and Aharonov--Casher effects. These interference effects\ninduce the Ising-coupled Ruderman--Kittel--Kasuya--Yosida (RKKY) interaction.\nWe discuss the inter- and intra-site spin conductance as well as charge\nconductance in the Kondo and the mixed-valence regimes using the slave boson\nmean field approximation."
    },
    {
        "anchor": "Charge and spin density response functions of the clean two-dimensional\n  electron gas with Rashba spin-orbit coupling at finite momenta and\n  frequencies: We analytically evaluate charge and spin density response functions of the\nclean two-dimensional electron gas with Rashba spin-orbit coupling at finite\nmomenta and frequencies. On the basis of our exact expressions we discuss the\naccuracy of the long-wavelength and the quasiclassical approximations. We also\nderive the static limit of spin susceptibilities and demonstrate, in\nparticular, how the Kohn-like anomalies in their derivatives are related to the\nspin-orbit modification of the Ruderman-Kittel-Kasuya-Yosida interaction.\nTaking into account screening and exchange effects of the Coulomb interaction,\nwe describe the collective charge and spin density excitation modes which\nappear to be coupled due to nonvanishing spin-charge response function.",
        "positive": "Tunable Radiation Field Aided Quantum Spin Hall Phase in Bi2Se3Thin Film: We show fledgling quantum spin Hall phase by the normal incidence of\nnear-infrared circularly polarized radiation field on Bismuth Selenide doped\nwith magnetic impurities. For this purpose, we start with a low-energy\ntwo-dimensional, time-dependent Hamiltonian. The time dependence in the\nHamiltonian arises due to the optical field describable by the associated gauge\nfield. We make use of the Floquet theory in the high-frequency limit to\ninvestigate the system. The optical field tuneability leads to the emergence of\nthe spin Hall phase, when intensity of the incident radiation is high, from the\nquantum anomalous Hall phase. Interestingly, the former phase is achievable\nhere even in the presence of the magnetic impurities."
    },
    {
        "anchor": "From Self-Assembly to Controlled-Assembly, From Optical Manipulation to\n  AFM Manipulation: Moving nanoparticles/atoms to study the nearfield interaction between them is\none of the many approaches to explore the optical and electrical properties of\nthese assemblies. Traditional approach included the self assembly by spinning\nor drying nanoparticles in aqua on the substrate is well practiced. Lithography\ntechnique is another popular approach to deposit limited nano/micro patterns on\nsubstrates. Later optical and mechanical manipulations were used to have more\ncontrol over moving individual elements of nano and microstructures and even\natoms. Optical tweezers, optical trapping and AFM manipulation are examples of\nthese precise approaches.",
        "positive": "Non-linear transport and heat dissipation in metallic carbon nanotubes: We show that the local temperature dependence of thermalized electron and\nphonon populations along metallic carbon nanotubes is the main reason behind\nthis non-linear transport characteristics in the high bias regime. Our model\nthat considers optical and zone boundary phonon emission as well as absorption\nby charge carriers is based on the solution of the Boltzmann transport equation\nthat assumes a local temperature along the nanotube, determined\nself-consistently with the heat transport equation. By using realistic\ntransport parameters, our results not only reproduce experimental data for\nelectronic transport, but also provide a coherent interpretation of thermal\nbreakdown under electric stress. In particular, electron and phonon\nthermalization prohibits ballistic transport in short nanotubes."
    },
    {
        "anchor": "Moir\u00e9 disorder effect in twisted bilayer graphene: We theoretically study the electronic structure of magic-angle twisted\nbilayer graphene with disordered moir\\'e patterns. By using an extended\ncontinuum model incorporating non-uniform lattice distortion, we find that the\nlocal density of states of the flat band is hardly broadened, but splits into\nupper and lower subbands in most places. The spatial dependence of the\nsplitting energy is almost exclusively determined by the local value of the\neffective vector potential induced by heterostrain, whereas the variation of\nlocal twist angle and local moir\\'e period give relatively minor effects on the\nelectronic structure. We explain the exclusive dependence on the local vector\npotential by a pseudo Landau level picture for the magic-angle flat band, and\nwe obtain an analytic expression of the splitting energy as a function of the\nstrain amplitude.",
        "positive": "A single quantum dot as an optical thermometer for mK temperatures: Resonant laser spectroscopy of a negatively charged self-assembled quantum\ndot is utilized to measure the temperature of a three dimensional fermionic\nreservoir down to 100mK. With a magnetic field applied to the quantum dot the\nsingle charged ground state is split by the Zeeman energy. As the quantum dot\nis in tunnel contact with a thermal electron reservoir, a thermal occupation of\nthe quantum dot spin states is enforced by co-tunneling processes. Resonant\nlaser induced fluorescence is used in order to measure the thermal quantum dot\nspin state population."
    },
    {
        "anchor": "Dynamical magnetic skyrmions: Spin transfer torque (STT) affords magnetic nanodevices the potential to act\nas memory, computing, and microwave elements operating at ultra-low currents\nand at a low energy cost. Spin transfer torque is not only effective in\nmanipulating well-known magnetic structures, such as domain walls and vortices,\nbut can also nucleate previously unattainable nano-magnetic objects, such as\nmagnetic droplets and skyrmions. While the droplet and the skyrmion are both\nsolitons, the former is inherently dynamic and non-topological, whereas the\nlatter is static but topologically protected. Here we show that it is possible\nto combine these properties into a novel topologically protected dynamical\nskyrmion, which adds additional degrees of freedom, and functionality, to both\ndroplet and skyrmion based applications. Unlike static skyrmions, the dynamical\nskyrmion can be nucleated and sustained without Dzyaloshinskii-Moriya\ninteraction (DMI) or dipole-dipole interaction (DDI), and is a generic soliton\nsolution independent of STT and damping once nucleated. In the presence of\nlarge DMI, the dynamical skyrmion experiences strong breathing with particular\npromise for skyrmion-based memory and microwave applications.",
        "positive": "Non-adiabatic transport in a quantum dot turnstile: We present a theoretical study of the electronic transport through a\nmany-level quantum dot driven by time-dependent signals applied at the contacts\nto the leads. If the barriers oscillate out of phase the system operates like a\nturnstile pump under a finite constant bias, as observed in the experiments of\nKouwenhoven {\\it et al.} [Phys. Rev. Lett. {\\bf 67}, 1626 (1991)]. The\ntime-dependent currents and their averages over succesive pumping periods are\ncomputed from the Keldysh formalism for tight-binding models. The calculation\nconsiders a sudden application of the pumping potentials at $t=0$ which leads\nto transient features of the time-dependent and averaged currents during the\nfirst pumping cycles which turn out to be important in the high-frequency\nregime. We show that in the transient regime the efficiency of the system as a\npump is rather poor because it mainly absorbs charge from both leads in order\nto fill the levels located below the bias window. Under a finite bias and a\nlow-frequency pumping signal the charge transferred across the system depends\non the number of levels located within the bias window. The internal charge\ndynamics and the role of energy sidebands are investigated. The so called\nsatellite peaks of the averaged current are observed also in the transient\nregime."
    },
    {
        "anchor": "Device Improvement and Circuit Performance Evaluation of complete SiGe\n  Double Gate Tunnel FETs: In recent part extensive simulation work has already been done on TFETs.\nHowever this is limited to device performance analysis. Evaluation of circuit\nperformance is a topic that is very little touched. This is due to the non\navailability of compact models of Tunnel FETs in the commercial simulator. In\nour paper for the first time we perform the circuit analysis of tunnel FETs\n(extended channel TFETs), we test them over basic digital circuit. We generate\nthe TFET models by using the model editor in Orcad. Extensive circuit\nsimulation is then performed by using these models in the Pspice circuit\ndesign. Performance of extended channel double gate TFET is evaluated on the\ngrounds of power and delay in inverter, nand gate, nor gate and ring\noscillator. Before that we perform device analysis of double gate extended\nchannel TFETs, extended channel has been tried before on SOI TFETs we try it\nfor the first time on double gate Si1-xGex TFETs. We even look at the effect of\nintroducing Si layer. The performance of this device is compared for different\nGe mole fraction and also with MOSFETs",
        "positive": "Quantized Casimir Force: We investigate the Casimir effect between two-dimensional electron systems\ndriven to the quantum Hall regime by a strong perpendicular magnetic field. In\nthe large separation (d) limit where retardation effects are essential we find\ni) that the Casimir force is quantized in units of 3\\hbar c \\alpha^2/(8\\pi^2\nd^4), and ii) that the force is repulsive for mirrors with same type of\ncarrier, and attractive for mirrors with opposite types of carrier. The sign of\nthe Casimir force is therefore electrically tunable in ambipolar materials like\ngraphene. The Casimir force is suppressed when one mirror is a charge-neutral\ngraphene system in a filling factor \\nu=0 quantum Hall state."
    },
    {
        "anchor": "Metallic clusters on a model surface: quantum versus geometric effects: We determine the structure and melting behavior of supported metallic\nclusters using an ab initio density-functional-based treatment of intracluster\ninteractions and an approximate treatment of the surface as an idealized smooth\nplane yielding an effective Lennard-Jones interaction with the ions of the\ncluster. We apply this model to determine the structure of sodium clusters\ncontaining from 4 to 22 atoms, treating the cluster-surface interaction\nstrength as a variable parameter. For a strong cluster-surface interaction, the\nclusters form two-dimensional (2D) monolayer structures; comparisons with\ncalculations of structure and dissociation energy performed with a classical\nGupta interatomic potential show clearly the role of quantum shell effects in\nthe metallic binding in this case, and evidence is presented that these shell\neffects correspond to those for a confined 2D electron gas. The thermodynamics\nand melting behavior of a supported Na_20 cluster is considered in detail using\nthe model for several cluster-surface interaction strengths. We find\nquantitative differences in the melting temperatures and caloric curve from\ndensity-functional and Gupta treatments of the valence electrons. A clear\ndimensional effect on the melting behavior is also demonstrated, with 2D\nstructures showing melting temperatures above those of the bulk or (at very\nstrong cluster-surface interactions) no clear meltinglike transition.",
        "positive": "Orientation-dependent electric transport and band filling in hole\n  co-doped epitaxial diamond films: Diamond, a well-known wide-bandgap insulator, becomes a low-temperature\nsuperconductor upon substitutional doping of carbon with boron. However,\nlimited boron solubility and significant lattice disorder introduced by boron\ndoping prevent attaining the theoretically-predicted high-temperature\nsuperconductivity. Here we present an alternative co-doping approach, based on\nthe combination of ionic gating and boron substitution, in hydrogenated thin\nfilms epitaxially grown on (111)- and (110)-oriented single crystals.\nGate-dependent electric transport measurements show that the effect of boron\ndoping strongly depends on the crystal orientation. In the (111) surface, it\nstrongly suppresses the charge-carrier mobility and moderately increases the\ngate-induced doping, while in the (110) surface it strongly increases the\ngate-induced doping with a moderate reduction in mobility. In both cases the\nmaximum total carrier density remains below $2{\\cdot}10^{14}\\,$cm$^{-2}$, three\ntimes lower than the value theoretically required for high-temperature\nsuperconductivity. Density-functional theory calculations show that this\nstrongly orientation-dependent effect is due to the specific energy-dependence\nof the density of states in the two surfaces. Our results allow to determine\nthe band filling and doping-dependence of the hole scattering lifetime in the\ntwo surfaces, showing the occurrence of a frustrated insulator-to-metal\ntransition in the (110) surface and of a re-entrant insulator-to-metal\ntransition in the (111) surface."
    },
    {
        "anchor": "Can Tunnel Transistors Scale Below 10nm?: The main promise of tunnel FETs (TFETs) is to enable supply voltage\n($V_{DD}$) scaling in conjunction with dimension scaling of transistors to\nreduce power consumption. However, reducing $V_{DD}$ and channel length\n($L_{ch}$) typically deteriorates the ON- and OFF-state performance of TFETs,\nrespectively. Accordingly, there is not yet any report of a high perfor]mance\nTFET with both low V$_{DD}$ ($\\sim$0.2V) and small $L_{ch}$ ($\\sim$6nm). In\nthis work, it is shown that scaling TFETs in general requires scaling down the\nbandgap $E_g$ and scaling up the effective mass $m^*$ for high performance.\nQuantitatively, a channel material with an optimized bandgap\n($E_g\\sim1.2qV_{DD} [eV]$) and an engineered effective mass ($m*^{-1}\\sim40\nV_{DD}^{2.5} [m_0^{-1}]$) makes both $V_{DD}$ and $L_{ch}$ scaling feasible\nwith the scaling rule of $L_{ch}/V_{DD}=30~nm/V$ for $L_{ch}$ from 15nm to 6nm\nand corresponding $V_{DD}$ from 0.5V to 0.2V.",
        "positive": "Subnanosecond Fluctuations in Low-Barrier Nanomagnets: Fast magnetic fluctuations due to thermal torques have useful technological\nfunctionality ranging from cryptography to probabilistic computing. The\ncharacteristic time of fluctuations in typical uniaxial anisotropy magnets\nstudied so far is bounded from below by the well-known energy relaxation\nmechanism. This time scales as $\\alpha^{-1}$, where $\\alpha$ parameterizes the\nstrength of dissipative processes. Here, we theoretically analyze the\nfluctuating dynamics in easy-plane and antiferromagnetically coupled\nnanomagnets. We find in such magnets, the dynamics are strongly influenced by\nfluctuating intrinsic fields, which give rise to an additional dephasing-type\nmechanism for washing out correlations. In particular, we establish two time\nscales for characterizing fluctuations (i) the average time for a nanomagnet to\nreverse|which for the experimentally relevant regime of low damping is governed\nprimarily by dephasing and becomes independent of $\\alpha$, (ii) the time scale\nfor memory loss of a single nanomagnet|which scales as $\\alpha^{-1/3}$ and is\ngoverned by a combination of energy dissipation and dephasing mechanism. For\ntypical experimentally accessible values of intrinsic fields, the resultant\nthermal-fluctuation rate is increased by multiple orders of magnitude when\ncompared with the bound set solely by the energy relaxation mechanism in\nuniaxial magnets. This could lead to higher operating speeds of emerging\ndevices exploiting magnetic fluctuations."
    },
    {
        "anchor": "Hierarchy of gaps and magnetic minibands in graphene in the presence of\n  the Abrikosov vortex lattice: We determine the structure of band and gaps in graphene encapsulated in\nhexagonal boron nitride and subjected to magnetic field of Abrikosov lattice of\nvortices in the underlying superconducting film. The spectrum features one\nnon-dispersive magnetic miniband at zero energy, separated by the largest gaps\nin the miniband spectrum from a pair of minibands resembling slightly broadened\nfirst Landau levels in graphene, suggesting the persistence of $\\nu = \\pm 2$\nquantum Hall effect states. Also, we identify occasional merging point of\nmagnetic minibands which feature Dirac-type dispersion at the consecutive\nminiband edges.",
        "positive": "Configurable Electrostatically Doped High Performance Bilayer Graphene\n  Tunnel FET: A bilayer graphene based electrostatically doped tunnel field-effect\ntransistor (BED-TFET) is proposed in this work. Unlike graphene nanoribbon\nTFETs in which the edge states deteriorate the OFF-state performance, BED-TFETs\noperate based on different bandgaps induced by vertical electric fields in the\nsource, channel, and drain regions without any chemical doping. The performance\nof the transistor is evaluated by self-consistent quantum transport\nsimulations. This device has several advantages: 1) ultra-low power (VDD=0.1V),\n2) high performance (ION/IOFF>104), 3) steep subthreshold swing (SS<10mv/dec),\nand 4) electrically configurable between N-TFET and P-TFET post fabrication.\nHere, the operation principle of the BED-TFET and its performance sensitivity\nto the device design parameters are studied."
    },
    {
        "anchor": "Polariton-based optical switch: Based on the studies of propagation of an exciton-polariton condensate in a\npatterned optical microcavity with an embedded graphene layer, we propose a\ndesign of a Y-shaped electrically-controlled optical switch. The polaritons are\ndriven by a time-independent force due to the microcavity wedge shape and by a\ntime-dependent drag force owing to the interaction of excitons in graphene and\nthe electric current running in a neighboring quantum well. It is demonstrated\nthat one can control the polariton flow direction by changing the direction of\nthe electric current. The simulations also show that an external electric field\nnormal to the microcavity plane can be utilized as an additional parameter that\ncontrols the propagation of the signals in the switch. By considering the\ntransient dynamics of the polariton condensate, we estimate the response speed\nof the switch. Finally, we propose a design of the polariton switch in a flat\nmicrocavity based on the geometrically identical Y-shaped quantum well and\ngraphene pattern where the polariton flow is only induced by the drag force.",
        "positive": "Observation of spin Coulomb drag in a two-dimensional electron gas: An electron propagating through a solid carries spin angular momentum in\naddition to its mass and charge. Of late there has been considerable interest\nin developing electronic devices based on the transport of spin, which offer\npotential advantages in dissipation, size, and speed over charge-based devices.\nHowever, these advantages bring with them additional complexity. Because each\nelectron carries a single, fixed value (-e) of charge, the electrical current\ncarried by a gas of electrons is simply proportional to its total momentum. A\nfundamental consequence is that the charge current is not affected by\ninteractions that conserve total momentum, notably collisions among the\nelectrons themselves. In contrast, the electron's spin along a given spatial\ndirection can take on two values, \"up\" and \"down\", so that the spin current and\nmomentum need not be proportional. Although the transport of spin polarization\nis not protected by momentum conservation, it has been widely assumed that,\nlike the charge current, spin current is unaffected by electron-electron (e-e)\ninteractions. Here we demonstrate experimentally not only that this assumption\nis invalid, but that over a broad range of temperature and electron density,\nthe flow of spin polarization in a two-dimensional gas of electrons is\ncontrolled by the rate of e-e collisions."
    },
    {
        "anchor": "Two-dimensional Graphene with Structural Defects: Elastic Mean Free\n  Path, Minimum Conductivity and Anderson Transition: Quantum transport properties of disordered graphene with structural defects\n(Stone-Wales and divacancies) are investigated using a realistic {\\pi}-{\\pi}*\ntight-binding model elaborated from ab initio calculations. Mean free paths and\nsemiclassical conductivities are then computed as a function of the nature and\ndensity of defects (using an order-N real-space Kubo-Greenwood method). By\nincreasing of the defect density, the decay of the semiclassical conductivities\nis predicted to saturate to a minimum value of 4e^2/{\\pi}h over a large range\n(plateau) of carrier density (> 0.5 10^{14}cm^{-2}). Additionally, strong\ncontributions of quantum interferences suggest that the Anderson localization\nregime could be experimentally measurable for a defect density as low as 1%.",
        "positive": "Twist-angle dependent proximity induced spin-orbit coupling in\n  graphene/topological insulator heterostructures: The proximity-induced spin-orbit coupling (SOC) in heterostructures of\ntwisted graphene and topological insulators (TIs) Bi$_2$Se$_3$ and Bi$_2$Te$_3$\nis investigated from first principles. To build commensurate supercells, we\nstrain graphene and correct thus resulting band offsets by applying a\ntransverse electric field. We then fit the low-energy electronic spectrum to an\neffective Hamiltonian that comprises orbital and spin-orbit terms. For twist\nangles 0$^\\circ\\leq\\Theta \\lessapprox 20^\\circ$, we find the dominant\nspin-orbit couplings to be of the valley-Zeeman and Rashba types, both a few\nmeV strong. We also observe a sign change in the induced valley-Zeeman SOC at\n$\\Theta\\approx 10^\\circ$. Additionally, the in-plane spin structure resulting\nfrom the Rashba SOC acquires a non-zero radial component, except at $0^\\circ$\nor $30^\\circ$. At $30^\\circ$ the graphene Dirac cone interacts directly with\nthe TI surface state. We therefore explore this twist angle in more detail,\nstudying the effects of gating, TI thicknesses, and lateral shifts on the SOC\nparameters. We find, in agreement with previous results, the emergence of the\nproximitized Kane-Mele SOC, with a change in sign possible by electrically\ntuning the Dirac cone within the TI bulk band gap."
    },
    {
        "anchor": "Particle-Hole Duality, Emergent Fermi Liquids and Fractional Chern\n  Insulators in Moir\u00e9 Flatbands: Moir\\'e flatbands, occurring, e.g., in twisted bilayer graphene at magic\nangles, have attracted ample interest due to their high degree of experimental\ntunability and the intriguing possibility of generating novel strongly\ninteracting phases. Here we consider the core problem of Coulomb interactions\nwithin fractionally filled spin and valley polarized Moir\\'e flatbands and\ndemonstrate that the dual description in terms of holes, which acquire a\nnontrivial hole dispersion, provides key physical intuition and enables the use\nof standard perturbative techniques for this strongly correlated problem. In\nexperimentally relevant examples such as ABC stacked trilayer and twisted\nbilayer graphene aligned with boron nitride, it leads to emergent\ninteraction-driven Fermi liquid states at electronic filling fractions down to\naround $1/3$ and $2/3$ respectively. At even lower filling fractions, the\nelectron density still faithfully tracks the single-hole dispersion while\nexhibiting distinct non-Fermi liquid behavior. Most saliently, we provide\nmicroscopic evidence that high temperature fractional Chern insulators can form\nin twisted bilayer graphene aligned with hexagonal boron nitride.",
        "positive": "Geometrical phase effects on the Wigner distribution of Bloch electrons: We investigate the dynamics of Bloch electrons using a density operator\nmethod and connect this approach with previous theories based on wave packets.\nWe study non-interacting systems with negligible disorder and strong spin-orbit\ninteractions, which have been at the forefront of recent research on\nspin-related phenomena. We demonstrate that the requirement of gauge invariance\nresults in a shift in the position at which the Wigner function of Bloch\nelectrons is evaluated. The present formalism also yields the correction to the\ncarrier velocity arising from the Berry phase. The gauge-dependent shift in\ncarrier position and the Berry phase correction to the carrier velocity\nnaturally appear in the charge and current density distributions. In the\ncontext of spin transport we show that the spin velocity may be defined in such\na way as to enable spin dynamics to be treated on the same footing as charge\ndynamics. Aside from the gauge-dependent position shift we find additional,\ngauge-covariant multipole terms in the density distributions of spin, spin\ncurrent and spin torque."
    },
    {
        "anchor": "The effect of electron dielectric response on the quantum capacitance of\n  graphene in a strong magnetic field: The quantum capacitance of graphene can be negative when the graphene is\nplaced in a strong magnetic field, which is a clear experimental signature of\npositional correlations between electrons. Here we show that the quantum\ncapacitance of graphene is also strongly affected by its dielectric\npolarizability, which in a magnetic field is wave vector-dependent. We study\nthis effect both theoretically and experimentally. We develop a theory and\nnumerical procedure for accounting for the graphene dielectric response, and we\npresent measurements of the quantum capacitance of high-quality graphene\ncapacitors on boron nitride. Theory and experiment are found to be in good\nagreement.",
        "positive": "Coalescence of ZnO nanowires grown from monodispersed Au nanoparticles: New insights into controlling nanowire merging phenomena are demonstrated in\ngrowth of thin ZnO nanowires using monodispersed Au colloidal nanoparticles as\ncatalyst. Both nanowire diameter and density were found to be strongly\ndependent on the density of Au nanoparticles. Structural analysis and spectral\ncathodoluminescence imaging of the c-plane nanowire cross-sections reveal that\nthin isolated nanowires growing from the Au nanoparticles begin to merge and\ncoalesce with neighbouring nanowires to form larger nanowires when their\nseparation reaches a threshold distance. Green luminescence, which is\noriginated from the remnants of constituent nanowires before merging, is\ndetected at the core of fused nanowires. The distribution of nanowire diameters\nand green emission were found to be strongly dependent on the density of the Au\nnanoparticles. The merging phenomenon is attributed to electrostatic\ninteractions between nanowire c-facets during growth and well-described by a\ncantilever bending model."
    },
    {
        "anchor": "Linear magnetization dependence of the intrinsic anomalous Hall effect: The anomalous Hall effect is investigated experimentally and theoretically\nfor ferromagnetic thin films of Mn$_5$Ge$_3$. We have separated the intrinsic\nand extrinsic contributions to the experimental anomalous Hall effect, and\ncalculated the intrinsic anomalous Hall conductivity from the Berry curvature\nof the Bloch states using first-principles methods. The intrinsic anomalous\nHall conductivity depends linearly on the magnetization, which can be\nunderstood from the long wavelength fluctuations of the spin orientation at\nfinite temperatures. The quantitative agreement between theory and experiment\nis remarkably good, not only near 0 K, but also at finite temperatures, up to\nabout ~ 240 K (0.8 T$_C$})",
        "positive": "Observation of ballistic upstream modes at fractional quantum Hall edges\n  of graphene: The structure of edge modes at the boundary of quantum Hall (QH) phases forms\nthe basis for understanding low energy transport properties. In particular, the\npresence of ``upstream'' modes, moving against the direction of charge current\nflow, is critical for the emergence of renormalized modes with exotic quantum\nstatistics. Detection of excess noise at the edge is a smoking gun for the\npresence of upstream modes. Here we report on noise measurements at the edges\nof fractional QH (FQH) phases realized in dual graphite-gated bilayer graphene\ndevices. A noiseless dc current is injected at one of the edge contacts, and\nthe noise generated at contacts at $L= 4\\,\\mu$m or $10\\,\\mu$m away along the\nupstream direction is studied. For integer and particle-like FQH states, no\ndetectable noise is measured. By contrast, for ``hole-conjugate'' FQH states,\nwe detect a strong noise proportional to the injected current, unambiguously\nproving the existence of upstream modes. The noise magnitude remaining\nindependent of length together with a remarkable agreement with our theoretical\nanalysis demonstrates the ballistic nature of upstream energy transport, quite\ndistinct from the diffusive propagation reported earlier in GaAs-based systems.\nOur investigation opens the door to the study of upstream transport in more\ncomplex geometries and in edges of non-Abelian phases in graphene."
    },
    {
        "anchor": "Functionalized Bismuth Films: Giant Gap Quantum Spin Hall and\n  Valley-Polarized Quantum Anomalous Hall States: The search for new large band gap quantum spin Hall (QSH) and quantum\nanomalous Hall (QAH) insulators is critical for their realistic applications at\nroom temperature. Here we predict, based on first principles calculations, that\nthe band gap of QSH and QAH states can be as large as 1.01 eV and 0.35 eV in an\nH-decorated Bi(111) film. The origin of this giant band gap lies both in the\nlarge spin-orbit interaction of Bi and the H-mediated exceptional electronic\nand structural properties. Moreover, we find that the QAH state also possesses\nthe properties of quantum valley Hall state, thus intrinsically realising the\nso-called valley-polarized QAH effect. We further investigate the realization\nof large gap QSH and QAH states in an H-decorated Bi(\\={1}10) film and\nX-decorated (X=F, Cl, Br, and I) Bi(111) films.",
        "positive": "Temperonic Crystal: a superlattice for temperature waves in graphene: The temperonic crystal, a periodic structure with a unit cell made of two\nslabs sustaining temperature wave-like oscillations on short time-scales, is\nintroduced. The complex-valued dispersion relation for the temperature scalar\nfield is investigated for the case of a localised temperature pulse. The\ndispersion discloses frequency gaps, tunable upon varying the slabs thermal\nproperties. Results are shown for the paradigmatic case of a graphene-based\ntemperonic crystal. The temperonic crystal extends the concept of superlattices\nto the realm of temperature waves, allowing for coherent control of ultrafast\ntemperature pulses in the hydrodynamic regime at above liquid nitrogen\ntemperatures."
    },
    {
        "anchor": "Cooling a micro-mechanical resonator by quantum back-action from a noisy\n  qubit: We study the role of qubit dephasing in cooling a mechanical resonator by\nquantum back-action. With a superconducting flux qubit as a specific example,\nwe show that ground-state cooling of a mechanical resonator can only be\nrealized if the qubit dephasing rate is sufficiently low.",
        "positive": "Second-order post-Hartree-Fock perturbation theory for the electron\n  current: Based on the super-fermion representation of quantum kinetic equations we\ndevelop nonequilibrium, post-Hartree-Fock many-body perturbation theory for the\ncurrent through a region of interacting electrons. We apply the theory to out\nof equilibrium Anderson model and discuss practical implementation of the\napproach. Our calculations show that nonequilibrium electronic correlations may\nproduce significant quantitative and qualitative corrections to mean-field\nelectronic transport properties. We find that the nonequilibrium leads to\nenhancement of electronic correlations."
    },
    {
        "anchor": "Spatio-temporal dynamics of shift current quantum pumping by femtosecond\n  light pulse: Shift current---a photocurrent induced by light irradiating\nnoncentrosymmetric materials in the absence of any bias voltage or built-in\nelectric field---is one of the mechanisms of the so-called bulk photovoltaic\neffect. It has been traditionally described as a nonlinear optical response of\nperiodic solids to continuous wave light using a perturbative formula, which is\nlinear in the intensity of light and which involves Berry connection describing\nthe shift in the center of mass position of the Wannier wave function\nassociated with the transition between the valence and conduction bands. We\nanalyze realistic two-terminal devices, where paradigmatic Rice-Mele model is\nsandwiched between two metallic electrodes, using recently developed\ntime-dependent nonequilibrium Green function algorithms scaling linearly in the\nnumber of time steps and capable of treating nonperturbative effects in the\namplitude of external time-dependent fields. This unveils novel features:\nsuperballistic transport, signified by time dependence of the displacement,\n$\\sim t^\\nu$ with $\\nu > 1$, of the photoexcited charge carriers from the\nregion where the femtosecond light pulse is applied toward the electrodes; and\nphotocurrent quadratic in light intensity at subgap frequencies of light due to\ntwo-photon absorption processes that were missed in previous perturbative\nanalyses. Furthermore, frequency dependence of the DC component of the\nphotocurrent reveals shift currents as a realization of nonadiabatic quantum\ncharge pumping enabled by breaking of left-right symmetry of the device\nstructure. This demonstrates that a much wider class of systems, than the\nusually considered polar noncentrosymmetric bulk materials, can be exploited to\ngenerate nonzero DC component of photocurrent in response to unpolarized light\nand optimize shift-current-based solar cells and optoelectronic devices.",
        "positive": "Dynamical Correlations in a Half-Filled Landau Level: We formulate a self-consistent field theory for the Chern-Simons fermions to\nstudy the dynamical response function of the quantum Hall system at $\\nu=1/2$.\nOur scheme includes the effect of correlations beyond the random-phase\napproximation (RPA) employed to this date for this system. The resulting\nzero-frequency density response function vanishes as the square of the wave\nvector in the long-wavelength limit. The longitudinal conductivity calculated\nin this scheme shows linear dependence on the wave vector, like the\nexperimentals results and the RPA, but the absolute values are higher than the\nexperimental results."
    },
    {
        "anchor": "Quantum nonlinear Hall effect induced by Berry curvature dipole in\n  time-reversal invariant materials: It is well-known that a non-vanishing Hall conductivity requires\ntime-reversal symmetry breaking. However, in this work, we demonstrate that a\nHall-like transverse current can occur in second-order response to an external\nelectric field in a wide class of time-reversal invariant and inversion\nbreaking materials, at both zero and twice the optical frequency. This\nnonlinear Hall effect has a quantum origin arising from the dipole moment of\nthe Berry curvature in momentum space, which generates a net anomalous velocity\nwhen the system is in a current-carrying state. We show that the nonlinear Hall\ncoefficient is a rank-two pseudo-tensor, whose form is determined by point\ngroup symmetry. We discus optimal conditions to observe this effect and propose\ncandidate two- and three-dimensional materials, including topological\ncrystalline insulators, transition metal dichalcogenides and Weyl semimetals.",
        "positive": "Chiral magnetic effect in the absence of Weyl node: The nodal points in a Weyl semimetal are generally considered as the causes\nof the chiral anomaly and the chiral magnetic effect (CME). Employing a\nlinear-response analysis of a two-band lattice model, we show that the Weyl\nnodes and thus the chirality are not required for the CME, while they remain\ncrucial for the chiral anomaly. Similar to the anomalous Hall effect, the CME\nresults directly from the Berry curvature of energy bands, even when there is\nno monopole source from the Weyl nodes. Therefore, the phenomenon of the CME\ncould be observed in a wider class of materials. Motivated by this result, we\nsuggest that the nodeless CME may appear in three-dimensional quantum anomalous\nHall insulators, but after they become metallic due to the band deformation\ncaused by inversion symmetry breaking."
    },
    {
        "anchor": "Direct and indirect exciton mixture in double quantum wells: The exciton system in double quantum well is considered under condition when\nthe ground state is the spatially indirect exciton. At high pumping growth of\nthe exciton concentration can lead to so significant increase of the indirect\nexciton energy that becomes equal to the direct exciton energy. Then further\nincrease of pumping leads to formation of mixed direct - indirect exciton\nphase. A rough estimate of the exciton energy in the mixed phase explains\npuzzling features of some recent exciton measurements. An experiment that would\nreveal main characteristic features of the mixed phase is suggested.",
        "positive": "Spin-orbit torque control of spin waves in a ferromagnetic waveguide: Spin-orbit torque (SOT) created by a spin current injected into a ferromagnet\nby an adjacent heavy metal represents an efficient tool for the excitation and\nmanipulation of spin waves. Here we report the micromagnetic simulations\ndescribing the influence of SOT on the propagation of spin waves in the\n$\\mathrm{W}/\\mathrm{CoFeB}/\\mathrm{MgO}$ nanostructure having\nvoltage-controlled magnetic anisotropy (VCMA). The simulations show that two\nspin waves travelling in the opposite directions can be generated in the center\nof the $\\mathrm{CoFeB}$ waveguide via the modulation of VCMA induced by a\nmicrowave voltage locally applied to the $\\mathrm{MgO}$ nanolayer. The\namplitudes of these waves exponentially decrease with the propagation distance\nwith similar decay lengths of about 2.5 $\\mu$m. In the presence of a direct\nelectric current injected into the $\\mathrm{W}$ film beneath the waveguide\ncenter, the decay lengths of two spin waves change in the opposite way owing to\ndifferent directions of the electric currents flowing in the underlying halves\nof the $\\mathrm{W}$ layer. Remarkably, above the critical current density\n$J_\\mathrm{W} \\approx 2 \\times 10^{10}$ A m$^{-2}$, SOT provides the\namplification of the spin wave propagating in one half of the waveguide and\nstrongly accelerates the attenuation of the wave travelling in the other half.\nAs a result, a long-distance spin-wave propagation takes place in a half of the\n$\\mathrm{CoFeB}$ waveguide only. Furthermore, by reversing the polarity of the\ndc voltage applied to the heavy-metal layer one can change the propagation area\nand switch the travel direction of the spin wave in the ferromagnetic\nwaveguide. Thus, the $\\mathrm{W}/\\mathrm{CoFeB}/\\mathrm{MgO}$ nanostructure can\nbe employed as an electrically controlled magnonic device converting the\nelectrical input signal into a spin signal, which can be transmitted to one of\ntwo outputs of the device."
    },
    {
        "anchor": "Deformed Fermi Surface Theory of Magneto-Acoustic Anomaly in Modulated\n  Quantum Hall Systems Near $\u03bd=1/2$ Hall Systems Near $\u03bd=1/2$: We introduce a new generic model of a deformed Composite Fermion-Fermi\nSurface (CF-FS) for the Fractional Quantum Hall Effect near $\\nu=1/2$ in the\npresence of a periodic density modulation. Our model permits us to explain the\nrecent surface acoustic wave observations of anisotropic anomalies[R.L Willett\net al,PRL vol78,4478 (1997);J.H.Smet et al, PRL vol 80,4538 (1998)] in sound\nvelocity and attenuation--appearance of peaks and anisotropy-- which originate\nfrom contributions to the conductivity tensor due to regions of the CF-FS which\nare flattened by the applied modulation. The calculated magnetic field and wave\nvector dependence of the CF conductivity, velocity shift, and attenuation agree\nwith experiments.",
        "positive": "Spin Hall effect of vorticity: Using mapping between topological defects in an easy-plane magnet and\nelectrical charges, we study interplay between vorticity and spin currents. We\ndemonstrate that the flow of vorticity is accompanied by the transverse spin\ncurrent generation -- an effect which can be termed as the spin Hall effect of\nvorticity. We study this effect across the BKT transition and establish the\nrole of dissipation and spin non-conservation in the crossover from spin\nsuperfluidity to diffusive spin transport. Our results pave the way for low\npower computing devices relying on vorticity and spin flows."
    },
    {
        "anchor": "Engineering Superconducting Phase Qubits: The superconducting phase qubit combines Josephson junctions into\nsuperconducting loops and defines one of the promising solid state device\nimplementations for quantum computing. While conventional designs are based on\nmagnetically frustrated superconducting loops, here we discuss the advantages\noffered by $\\pi$-junctions in obtaining naturally degenerate two-level systems.\nStarting from a basic five-junction loop, we show how to construct degenerate\ntwo-level junctions and superconducting phase switches. These elements are then\neffectively engineered into a superconducting phase qubit which operates\nexclusively with switches, thus avoiding permanent contact with the environment\nthrough external biasing. The resulting superconducting phase qubits can be\nunderstood as the macroscopic analogue of the `quiet' s-wave-d-wave-s-wave\nJosephson junction qubits introduced by Ioffe {\\it et al.} [Nature {\\bf 398},\n679 (1999)].",
        "positive": "Kondo effect and spin-active scattering in ferromagnet-superconductor\n  junctions: We study the interplay of superconducting and ferromagnetic correlations on\ncharge transport in different geometries with a focus on both a quantum point\ncontact as well as a quantum dot in the even and the odd state with and without\nspin-active scattering at the interface. In order to obtain a complete picture\nof the charge transport we calculate the full counting statistics in all cases\nand compare the results with experimental data. We show that spin-active\nscattering is an essential ingredient in the description of quantum point\ncontacts. This holds also for quantum dots in an even charge state whereas it\nis strongly suppressed in a typical Kondo situation. We explain this feature by\nthe strong asymmetry of the hybridisations with the quantum dot and show how\nKondo peak splitting in a magnetic field can be used for spin filtering. For\nthe quantum dot in the even state spin-active scattering allows for an\nexplanation of the experimentally observed mini-gap feature."
    },
    {
        "anchor": "Superconductivity of neutral modes in quantum Hall edges: Edges of quantum Hall phases give rise to a multitude of exotic modes\nsupporting quasiparticles of different values of charge and quantum statistics.\nAmong these are neutralons (chargeless anyons with semion statistics), which\nwere found to be ubiquitous in fractional quantum Hall matter. Studying and\nmanipulating the neutral sector is an intriguing and interesting challenge, all\nthe more so since these particles are accessible experimentally. Here we\naddress the limit of strongly-interacting neutralons giving rise to neutralon\nsuperconductivity, where pairing is replaced by a quarteting mechanism. We\ndiscuss several manifestations of this effect, realizable in existing\nexperimental platforms. Furthermore, this superconducting gapping mechanism may\nbe exploited to facilitate the observation of interference of the accompanying\ncharged anyons.",
        "positive": "Large nuclear spin polarization in gate-defined quantum dots using a\n  single-domain nanomagnet: The electron-nuclei (hyperfine) interaction is central to spin qubits in\nsolid state systems. It can be a severe decoherence source but also allows\ndynamic access to the nuclear spin states. We study a double quantum dot\nexposed to an on-chip single-domain nanomagnet and show that its inhomogeneous\nmagnetic field crucially modifies the complex nuclear spin dynamics such that\nthe Overhauser field tends to compensate external magnetic fields. This turns\nout to be beneficial for polarizing the nuclear spin ensemble. We reach a\nnuclear spin polarization of ~50%, unrivaled in lateral dots, and explain our\nmanipulation technique using a comprehensive rate equation model."
    },
    {
        "anchor": "Phonon Effects on Population Inversion in Quantum Dots: Resonant,\n  Detuned and Frequency-swept Excitations: The effect of acoustic phonons on different light-induced excitations of a\nsemiconductor quantum dot is investigated. Resonant excitation of the quantum\ndot leads to Rabi oscillations, which are damped due to the phonon interaction.\nWhen the excitation frequency is detuned, an occupation can only occur due to\nphonon absorption or emission processes. For frequency-swept excitations a\npopulation inversion is achieved through adiabatic rapid passage, but the\ninversion is also damped by phonons. For all three scenarios the influence of\nthe phonons depends non-monotonically on the pulse area.",
        "positive": "Trions and biexcitons in a nanowire: A theory of the trion and biexciton in a nanowire (NW) in the framework of\nthe effective-mass model using the Born-Oppenheimer approximation is presented.\nWe consider the formation of trions and biexcitons under the action of both the\nlateral confinement and the localization potential. The analytical expressions\nfor the binding energy and eigenfunctions of the trion and biexciton are\nobtained and expressed by means of matrix elements of the effective\none-dimensional cusp-type Coulomb potentials whose parameters are determined\nself-consistently by employing the same eigenfunctions of the confined electron\nand hole states. Our calculations for the ZnO/ZnMgO, CdSe/ZnS and CdSe/CdS\ncore/shell cylindrical shaped NWs show that the trion and biexciton binding\nenergy in NWs are size-dependent and for the same input parameters the\nbiexciton binding energy in NWs is always larger than the binding energy of the\ntrion. The trion and biexciton remain stable in CdSe/ZnS NW with the increase\nof the dielectric shell, while in ZnO/ZnMgO NW they become unstable when the\nsurrounding dielectric shell exceeds 2.5 nm and 2 nm for each, respectively.\nThe associative ionization of biexciton antibonding states into trion bonding\nstates is studied. Based on the results for size dependence of biexciton\nbinding energy and probability associative ionization an optimal radius for\noptoelectronic application NW is suggested."
    },
    {
        "anchor": "Energy loss rates of hot Dirac fermions in epitaxial, exfoliated and CVD\n  graphene: Energy loss rates for hot carriers in graphene have been measured using\ngraphene produced by epitaxial growth on SiC, exfoliation and chemical vapour\ndeposition (CVD). It is shown that the temperature dependence of the energy\nloss rates measured with high-field damped Shubnikov-de Haas oscillations, and\nthe temperature dependence of the weak localization peak close to zero field\ncorrelate well, with the high-field measurements understating the energy loss\nrates by $\\sim$40% compared to the low-field results. The energy loss rates for\nall graphene samples follow a universal scaling of $T_{e}^4$ at low\ntemperatures and depend weakly on carrier density $\\propto$ n$^{-1/2}$ evidence\nfor enhancement of the energy loss rate due to disorder in CVD samples.",
        "positive": "Bias-dependent electron spin lifetimes in n-GaAs and the role of donor\n  impact ionization: In bulk n-GaAs epilayers doped near the metal-insulator transition, we study\nthe evolution of electron spin lifetime $\\tau_s$ as a function of applied\nlateral electrical bias $E_x$. $\\tau_s$ is measured via the Hanle effect using\nmagneto-optical Kerr rotation. At low temperatures (T<10 K, where electrons are\npartially localized and $\\tau_s > 100$ ns at zero bias), a marked collapse of\n$\\tau_s$ is observed when $E_x$ exceeds the donor impact ionization threshold\nat $\\sim$10 V/cm. A steep increase in the concentration of warm delocalized\nelectrons -- subject to Dyakonov-Perel spin relaxation -- accounts for the\nrapid collapse of $\\tau_s$, and strongly influences electron spin transport in\nthis regime."
    },
    {
        "anchor": "Plasmonic Nature of the Terahertz Conductivity Peak in Single-Wall\n  Carbon Nanotubes: Plasmon resonance is expected to occur in metallic and doped semiconducting\ncarbon nanotubes in the terahertz frequency range, but its convincing\nidentification has so far been elusive. The origin of the terahertz\nconductivity peak commonly observed for carbon nanotube ensembles remains\ncontroversial. Here we present results of optical, terahertz, and DC transport\nmeasurements on highly enriched metallic and semiconducting nanotube films. A\nbroad and strong terahertz conductivity peak appears in both types of films,\nwhose behaviors are consistent with the plasmon resonance explanation, firmly\nruling out other alternative explanations such as absorption due to\ncurvature-induced gaps.",
        "positive": "Finite Size Effect in Amorphous Indium oxide: We study the low temperature magneto-transport properties of several highly\ndisordered amorphous Indium oxide(a:InO) samples. Simultaneously fabricated\ndevices comprising a 2-dimensional (2D) film and 10 $\\mu$m long wires of\ndifferent widths were measured to investigate the effect of size as we approach\nthe 1D limit, which is around 4 times the correlation length, and happens to be\naround 100 nm for a:InO. The film and the wires showed magnetic field ({\\it B})\ninduced superconductor to insulator transition (SIT). In the superconducting\nside, the resistance increased with decrease in wire width, whereas, an\nopposite trend is observed in the insulating side. We find that this effect can\nbe explained in light of charge-vortex duality picture of the SIT. Resistance\nof the 2D film follows an activated behavior over the temperature ($T$),\nwhereas, the wires show a crossover from the high-$T$ activated to a\n$T$-independent behavior. At high temperature regime the wires' resistance\nfollow the film's until they deviate and became independent of $T$. We find\nthat temperature at which this deviation occurs evolve with magnetic field and\nthe width of the wire, which show the effect of finite size on the transport."
    },
    {
        "anchor": "Surface Plasmon Assisted Kondo Resonances on a Metallic Nanowire: In this letter we propose an experiment to measure the Kondo effect for\nmagnetic atoms adsorbed on the surface of a metallic nanowire. In addition to\nthe traditional sp-d hybridization, by introducing the strong electromagnetic\nfield of the localized surface plasmon on the nanowire, we show that it is\npossible to observe additional sp-d electron transfer processes assisted by\nsurface plasmons. Due to the good surface-to-volume ratio of the nanowire, the\nKondo resonances here would be revealed as multiple anti-resonances in the\ndifferential conductance versus bias voltage curve.",
        "positive": "Universality of Hofstadter butterflies on hyperbolic lattices: Motivated by recent experimental breakthroughs in realizing hyperbolic\nlattices in superconducting waveguides and electric circuits, we compute the\nHofstadter butterfly on regular hyperbolic tilings. By utilizing large\nhyperbolic lattices with periodic boundary conditions, we obtain the true\nhyperbolic bulk spectrum that is unaffected by contributions from boundary\nstates. Our results reveal that the butterfly spectrum with large extended\ngapped regions prevails and that its shape is universally determined by the\nnumber of edges of the fundamental tile, while the fractal structure is lost in\nsuch a non-Euclidean case. We explain how these intriguing features are related\nto the nature of Landau levels in hyperbolic space, and how they could be\nverified experimentally."
    },
    {
        "anchor": "Electron transport properties in high-purity Ge down to cryogenic\n  temperatures: Electron transport in Ge at various temperatures down to 20 mK has been\ninvestigated using particle Monte Carlo simulation taking into account ionized\nimpurity and inelastic phonon scattering. The simulations account for the\nessential features of electron transport at cryogenic temperature: Ohmic\nregime, anisotropy of the drift velocity relative to the direction of the\nelectric field, as well as a negative differential mobility phenomenon along\nthe <111> field orientation. Experimental data for the electron velocities are\nreproduced with a satisfactory accuracy. Examples of electron position in the\nreal space during the simulations are given and evidence separated clouds of\nelectrons propagating along different directions depending on the valley they\nbelong.",
        "positive": "Writing and storing information in an array of magnetic vortex nanodisks\n  using their azimuthal modes: The switching of a vortex core of a single disk in an array of a multilayer\nsystem is investigated by micromagnetic simulation. We found that the\nperpendicular uniaxial anisotropy (PUA) decreases the frequencies of the\nazimuthal mode in disks with magnetic vortex configuration. We obtained a phase\ndiagram of magnetic field intensity vs. frequency of the azimuthal mode, as a\nfunction of the value of perpendicular uniaxial anisotropy. We demonstrated\nthat rotating magnetic fields (CW and CCW) with frequency equal to azimuthal\nmodes can be used to switch the vortex core of single disks in a disk array.\nThis allows obtaining different memory states with a single array of nanodisks,\nand therefore writing information through the application of rotating fields."
    },
    {
        "anchor": "Nuclear Spin Relaxation Time due to the Orbital Currents in Dirac\n  Electron Systems: The nuclear spin relaxation time $T_1$ is calculated taking account of the\ncontributions from orbital currents of Dirac electrons. We consider a simple\nmodel of non-interacting Dirac electron gas in the three-dimensional bulk\nsystem. The obtained result shows $T^3$ dependence of $1/T_1$ at temperatures\n$T$ above the energy gap. This temperature dependence agrees qualitatively with\nthe recent $\\beta$-NMR experiment on the bulk of the topological insulator\n$\\mathrm{Bi}_{0.9}\\mathrm{Sb}_{0.1}$.",
        "positive": "Magnonic Hall Effect and Magnonic Holography of Hopfions: Hopfions are localized and topologically non-trivial magnetic configurations\nthat have received considerable attention in recent years. Through a\nmicromagnetic approach, we analyze the scattering of spin waves by magnetic\nhopfions. We show that the spin waves experience an emergent electromagnetic\nfield related to the topological properties of the hopfion. We find that spin\nwaves propagating along the hopfion symmetry axis are deflected by the magnetic\ntexture, which acts as a convergent or divergent lens, depending on the spin\nwave propagation direction. The effect differs for spin waves propagating along\nthe plane perpendicular to the symmetry axis. In the last case, they respond\nwith a skew scattering and a closely related Aharonov-Bohm effect. This allows\nprobing the existence of a magnetic hopfion by magnonic holography."
    },
    {
        "anchor": "Stark effect of excitons in individual air-suspended carbon nanotubes: We investigate electric-field induced redshifts of photoluminescence from\nindividual single-walled carbon nanotubes. The shifts scale quadratically with\nfield, while measurements with different excitation powers and energies show\nthat effects from heating and relaxation pathways are small. We attribute the\nshifts to the Stark effect, and characterize nanotubes with different\nchiralities. By taking into account exciton binding energies for air-suspended\ntubes, we find that theoretical predictions are in quantitative agreement.",
        "positive": "A hybrid double-dot in silicon: We report electrical measurements of a single arsenic dopant atom in the\ntunnel-barrier of a silicon SET. As well as performing electrical\ncharacterization of the individual dopant, we study series electrical transport\nthrough the dopant and SET. We measure the triple points of this hybrid double\ndot, using simulations to support our results, and show that we can tune the\nelectrostatic coupling between the two sub-systems."
    },
    {
        "anchor": "Aharonov-Bohm effect for excitons in a semiconductor quantum ring\n  dressed by circularly polarized light: We show theoretically that the strong coupling of circularly polarized\nphotons to an exciton in ring-like semiconductor nanostructures results in\nphysical nonequivalence of clockwise and counterclockwise exciton rotations in\nthe ring. As a consequence, the stationary energy splitting of exciton states\ncorresponding to these mutually opposite rotations appears. This excitonic\nAharonov-Bohm effect depends on the intensity and frequency of the circularly\npolarized field and can be detected in state-of-the-art optical experiments.",
        "positive": "A discrete formulation for three-dimensional winding number: For a smooth map $g\\colon X \\to U(N)$, where $X$ is a three-dimensional,\noriented, and closed manifold, the winding number or the map's degree is\ndefined by $W_3 = \\frac{1}{24\\pi^2} \\int_{X}\n\\mathrm{Tr}\\left[(g^{-1}dg)^3\\right]$. We introduce a method to compute $W_3$\nusing a discrete approximation of $X$ so that the result is manifestly\nquantized."
    },
    {
        "anchor": "Unusual resistance-voltage dependence of nanojunctions during\n  electromigration in ultra-high vacuum: The electrical resistance R of metallic nanocontacts subjected to controlled\ncyclic electromigration in ultra-high vacuum has been investigated in-situ as a\nfunction of applied voltage V. For sufficiently small contacts, i.e., large\nresistance, a decrease of R(V) while increasing V is observed. This effect is\ntentatively attributed to the presence of contacts separated by thin vacuum\nbarriers in parallel to ohmic nanocontacts. Simple model calculations indicate\nthat both thermal activation or tunneling can lead to this unusual behavior. We\ndescribe our data by a tunneling model whose key parameter, i.e., the tunneling\ndistance, changes because of thermal expansion due to Joule heating and/or\nelectrostatic strain arising from the applied voltage. Oxygen exposure during\nelectromigration prevents the formation of negative R(V) slopes, and at the\nsame time enhances the probability of uncontrolled melting, while other gases\nshow little effects. In addition, indication for field emission has been\nobserved in some samples",
        "positive": "Cotunneling, current blockade, and backaction forces in nanobeams close\n  to the Euler buckling instability: Single-electron transistors embedded in a vibrating nanoresonator such as a\ndoubly-clamped carbon nanotube exhibit effects stemming from the coupling\nbetween electronic and vibrational degrees of freedom. In particular, a\ncapacitive electromechanical coupling induces a blockade of the current at low\nbias voltage. It has been recently shown theoretically within a\nsequential-tunneling approximation that this current blockade can be enhanced\nby orders of magnitude when the suspended structure is brought to the Euler\nbuckling instability. Here, we investigate the role of cotunneling on the\npredicted enhancement and show that the latter is not suppressed by cotunneling\neffects. We further demonstrate that despite the fact that the current blockade\nis difficult to measure far from the Euler instability, the backaction of the\ncurrent flow on the nanobeam frequency may be easier to observe."
    },
    {
        "anchor": "Spin-momentum locking induced non-local voltage in topological insulator\n  nanowire: The momentum and spin of charge carriers in the topological insulators are\nconstrained to be perpendicular to each other due to the strong spin-orbit\ncoupling. We have investigated this unique spin-momentum locking property in\nSb2Te3 topological insulator nanowires by injecting spin-polarized electrons\nthrough magnetic tunnel junction electrodes. Non-local voltage measurements\nexhibit a symmetry with respect to the magnetic field applied perpendicular to\nthe nanowire channel, which is remarkably different from that of a non-local\nmeasurement in a channel that lacks spin-momentum locking. In stark contrast to\nconventional non-local spin valves, simultaneous reversal of magnetic moments\nof all magnetic contacts to the Sb2Te3 nanowire alters the non-local voltage.\nThis unusual symmetry is a clear signature of the spin-momentum locking in the\nSb2Te3 nanowire surface states.",
        "positive": "Edge and Interfacial States in a 2D Topological Insulator:Bi(111)\n  Bilayer on Bi$_{2}$Te$_{2}$Se: The electronic states of a single Bi(111) bilayer and its edges, suggested as\na two dimensional topological insulator, are investigated by scanning tunneling\nspectroscopy (STS) and first-principles calculations. Well-ordered bilayer\nfilms and islands with zigzag edges are grown epitaxially on a cleaved\nBi$_{2}$Te$_{2}$Se crystal. The calculation shows that the band gap of the Bi\nbilayer closes with a formation of a new but small hybridization gap due to the\nstrong interaction between Bi and Bi$_{2}$Te$_{2}$Se. Nevertheless, the\ntopological nature of the Bi bilayer and the topological edge state are\npreserved only with an energy shift. The edge-enhanced local density of states\nare identified and visualized clearly by STS in good agreement with the\ncalculation. This can be the sign of the topological edge state, which\ncorresponds to the quantum spin Hall state. The interfacial state between Bi\nand Bi$_{2}$Te$_{2}$Se is also identified inside the band gap region. This\nstate also exhibits the edge modulation, which was previously interpreted as\nthe evidence of the topological edge state [F. Yang et al., Phys. Rev. Lett.\n109, 016801 (2012)]."
    },
    {
        "anchor": "Calculation of the Electron Spin Relaxation Times in InSb and InAs by\n  the Projection-Reduction Method: The electron spin relaxation times in a system of electrons interacting with\npiezoelectric phonons mediated through spin-orbit interactions were calculated\nusing the formula derived from the projection-reduction method. The results\nshowed that the temperature and magnetic field dependence of the relaxation\ntimes in InSb and InAs were similar. The piezoelectric material constants\nobtained by a comparison with the reported experimental result were Ppe = 4.0 x\n10^21 eV/m for InSb and Ppe = 6.7 x 10^21 eV/m for InAs. The relaxation of the\nelectron spin can be explained by the Elliot-Yafet process at a high field\nlimit.",
        "positive": "Manipulation of two spin qubits in a double quantum dot using an\n  electric field: We propose purely electric manipulation of spin qubits by means of the\nspin-orbit interaction (SOI) {\\it without magnetic field or magnets} in a\ndouble-quantum dot. All the unitary transformations can be constructed by the\ntime-dependent Dzyaloshinsky-Moriya interaction between the two spins, which\narises from the Rashba SOI modulated by electric field. As a few\ndemonstrations, we study both analytically and numerically the three\noperations, i.e., (A) the spin initialization, (B) the two-spin rotation in the\nopposite directions, and (C) the two-spin rotation in the same direction. The\neffects of the relaxation and the feasibility of this proposal are also\ndiscussed."
    },
    {
        "anchor": "Tuning emission energy and fine structure splitting in quantum dots\n  emitting in the telecom O-band: We report on optical investigations of MOVPE-grown InGaAs/GaAs quantum dots\nemitting at the telecom O-band that were integrated onto uniaxial piezoelectric\nactuators. This promising technique, which does not degrade the optical quality\nor performances of the quantum emitters, enables us to tune the quantum dot\nemission wavelengths and their fine-structure splitting. By spectrally\nanalyzing the emitted light with respect to its polarization, we are able to\ndemonstrate the cancelation of the fine structure splitting within the\nexperimental resolution limit. This work represents an important step towards\nthe high-yield generation of entangled photon pairs at telecommunication\nwavelength, together with the capability to precisely tune the emission to\ntarget wavelengths.",
        "positive": "Electronic transport in disordered MoS$_2$ nanoribbons: We study the electronic structure and transport properties of zigzag and\narmchair monolayer molybdenum disulfide nanoribbons using an 11-band\ntight-binding model that accurately reproduces the material's bulk band\nstructure near the band gap. We study the electronic properties of pristine\nzigzag and armchair nanoribbons, paying particular attention to the edges\nstates that appear within the MoS$_2$ bulk gap. By analyzing both their orbital\ncomposition and their local density of states, we find that in\nzigzag-terminated nanoribbons these states can be localized at a single edge\nfor certain energies independent of the nanoribbon width. We also study the\neffects of disorder in these systems using the recursive Green's function\ntechnique. We show that for the zigzag nanoribbons, the conductance due to the\nedge states is strongly suppressed by short-range disorder such as vacancies.\nIn contrast, the local density of states still shows edge localization. We also\nshow that long-range disorder has a small effect on the transport properties of\nnanoribbons within the bulk gap energy window."
    },
    {
        "anchor": "Scanning Gate Microscopy on Graphene: Charge Inhomogeneity and Extrinsic\n  Doping: We have performed scanning gate microscopy (SGM) on graphene field effect\ntransistors (GFET), using a biased metallic nanowire coated with a dielectric\nlayer as a contact mode tip and local top gate. Electrical transport through\ngraphene at various back gate voltages is monitored as a function of tip\nvoltage and tip position. Near the Dirac point, the dependence of graphene\nresistance on tip voltage shows a significant variation with tip position. SGM\nimaging reveals mesoscopic domains of electron-doped and hole-doped regions.\nOur measurements indicate a substantial spatial fluctuation (on the order of\n10^12/cm^2) in the carrier density in graphene due to extrinsic local doping.\nImportant sources for such doping found in our samples include metal contacts,\nedges of graphene, structural defects, and resist residues.",
        "positive": "Experimental investigation of the breakdown of the Onsager-Casimir\n  relations: We use magnetoconductance fluctuation measurements of phase-coherent\nsemiconductor billiards to quantify the contributions to the nonlinear electric\nconductance that are asymmetric under reversal of magnetic field. We\nexperimentally determine that the average asymmetric contribution is linear in\nmagnetic field (for magnetic flux much larger than one flux quantum) and that\nits magnitude depends on billiard geometry. In addition, we find an unexpected\nasymmetry in the power spectrum characteristics of the magnetoconductance with\nrespect to reversal of magnetic field and bias voltage."
    },
    {
        "anchor": "Neutral Fermion Excitations in the Moore-Read state at \u03bd=5/2: We present evidence supporting the weakly paired Moore-Read phase in the\nhalf-filled second Landau level, focusing on some of the qualitative features\nof its excitations. Based on numerical studies, we show that systems with odd\nparticle number at the flux $N_\\phi=2N-3$ can be interpreted as a neutral\nfermion mode of one unpaired fermion, which is gapped. The mode is found to\nhave two distinct minima, providing a signature that could be observed by\nphotoluminescence. In the presence of two quasiparticles the same neutral\nfermion excitation is shown to be gapless, confirming expectations for\nnon-Abelian statistics of the Ising model with degenerate fusion channels 1 and\n$\\psi$.",
        "positive": "A low-field temperature-dependent EPR signal in terraced MgO:Mn2+\n  nanoparticles: an enhanced Zeeman splitting in the wide-bandgap oxide: Mn2+ ion doping is used as an electron paramagnetic resonance (EPR) probe to\ninvestigate the influence of low-coordination structural defects such as step\nedges at the surface of terraced (001) MgO nanoparticles on the electronic\nproperties. Beside the well-known hyperfine sextet of Mn2+ ions in the cubic\ncrystal field of MgO, an additional EPR feature with a striking non-monotonous\ntemperature dependent shift of the g-factor is observed in terraced\nnanoparticles in the temperature range from 4K to room temperature. By linking\nthe difference in the temperature dependence of the Mn2+ sextet intensity in\ncubic and terraced nanoparticles with the possible s-d exchange shift and\nenhanced Zeeman splitting we conclude that the novel EPR feature originates\nfrom the loosely trapped charge-compensating carriers at the abundant\nstructural defects at the surface of terraced nanoparticles due to their\nexchange interaction with neighboring Mn2+ ions."
    },
    {
        "anchor": "Elastic Gauge Fields and Hall Viscosity of Dirac Magnons: We analyze the coupling of elastic lattice deformations to the magnon degrees\nof freedom of magnon Dirac materials. For a Honeycomb ferromagnet we find that,\nas it happens in the case of graphene, elastic gauge fields appear coupled to\nthe magnon pseudospinors. For deformations that induce constant pseudomagnetic\nfields, the spectrum around the Dirac nodes splits into pseudoLandau levels. We\nshow that when a Dzyaloshinskii-Moriya interaction is considered, a topological\ngap opens in the system and a Chern-Simons effective action for the elastic\ndegrees of freedom is generated. Such a term encodes a phonon Hall viscosity\nresponse, entirely generated by fluctuations of magnons living in the vicinity\nof the Dirac points. The magnon Hall viscosity vanishes at zero temperature,\nand grows as temperature is raised and the states around the Dirac points are\nincreasingly populated.",
        "positive": "Photocurrent-based detection of Terahertz radiation in graphene: Graphene is a promising candidate for the development of detectors of\nTerahertz (THz) radiation. A well-known detection scheme due to Dyakonov and\nShur exploits the confinement of plasma waves in a field-effect transistor\n(FET), whereby a dc photovoltage is generated in response to a THz field. This\nscheme has already been experimentally studied in a graphene FET [L. Vicarelli\net al., Nature Mat. 11, 865 (2012)]. In the quest for devices with a better\nsignal-to-noise ratio, we theoretically investigate a plasma-wave photodetector\nin which a dc photocurrent is generated in a graphene FET. The rectified\ncurrent features a peculiar change of sign when the frequency of the incoming\nradiation matches an even multiple of the fundamental frequency of plasma waves\nin the FET channel. The noise equivalent power per unit bandwidth of our device\nis shown to be much smaller than that of a Dyakonov-Shur detector in a wide\nspectral range."
    },
    {
        "anchor": "Dirac States in an Inclined Two-Dimensional Su-Schrieffer-Heeger Model: We propose to realize Dirac states in an inclined two-dimensional\nSu-Schrieffer-Heeger model on a square lattice. We show that a pair of Dirac\npoints protected by space-time inversion symmetry appear in the semimetal\nphase. The locations of these Dirac points are not pinned to any high-symmetry\npoints of the Brillouin zone but are tunable through parameter modulations.\nInterestingly, the merging of two Dirac points undergoes a topological phase\ntransition that leads to either a weak topological insulator or a nodal-line\nsemimetal. We provide a systematic analysis of these topological phases from\nboth bulk and boundary perspectives combined with symmetry arguments. We also\ndiscuss feasible experimental platforms to realize our model.",
        "positive": "Boosting room temperature tunnel magnetoresistance in hybrid magnetic\n  tunnel junctions under electric bias: Spin-resolved electron symmetry filtering is a key mechanism behind giant\ntunneling magnetoresistance (TMR) in Fe/MgO/Fe and similar magnetic tunnel\njunctions (MTJs), providing room temperature functionality in modern spin\nelectronics. However, the core process of the electron symmetry filtering\nbreaks down under applied bias, dramatically reducing the TMR above 0.5 V. This\nstrongly hampers the application range of MTJs. To circumvent the problem,\nresonant tunneling between ferromagnetic electrodes through quantum well states\nin thin layers has been used so far. This mechanism, however, is mainly\neffective at low temperatures. Here, a fundamentally different approach is\ndemonstrated, providing a strong TMR boost under applied bias in\nV/MgO/Fe/MgO/Fe/Co hybrids. This pathway uses spin orbit coupling (SOC)\ncontrolled interfacial states in vanadium, which contrary to the V(001) bulk\nstates are allowed to tunnel to Fe(001) at low biases. The experimentally\nobserved strong increase of TMR with bias is modelled using two nonlinear\nresistances in series, with the low bias conductance of the first (V/MgO/Fe)\nelement being boosted by the SOC-controlled interfacial states, while the\nconductance of the second (Fe/MgO/Fe) junctions controlled by the relative\nalignment of the two ferromagnetic layers. These results pave a way to\nunexplored and fundamentally different spintronic device schemes, with\ntunneling magnetoresistance uplifted under applied electric bias."
    },
    {
        "anchor": "Enhancing the sensitivity and selectivity of pyrene-based sensors for\n  detection of small gaseous molecules via destructive quantum interference: Graphene-based sensors are exceptionally sensitive with high carrier mobility\nand low intrinsic noise, and have been intensively investigated in the past\ndecade. The detection of individual gas molecules has been reported, albeit the\nunderlying sensing mechanism is not yet well understood. We focus on the\nadsorption of NO$_2$, H$_2$O, and NH$_3$ on a molecular junction with a pyrene\ncore, which can be considered as a minimal graphene-like unit. We\nsystematically investigate the chemiresistive response within the framework of\ndensity functional theory and non-equilibrium Green's functions. We highlight\nthe fundamental role of quantum interference (QI) in the sensing process, and\nwe propose it as a paradigmatic mechanism for sensing. Owing to the open-shell\ncharacter of NO$_2$, its interaction with pyrene gives rise to a Fano resonance\nthereby triggering the strongest chemiresistive response, while the weaker\ninteractions with H$_2$O and NH$_3$ result in lower sensitivity. We demonstrate\nthat by exploiting destructive QI arising in the meta-substituted pyrene, it is\npossible to calibrate the sensor to enhance both its sensitivity and chemical\nselectivity by almost two orders of magnitude so that individual molecules can\nbe detected and distinguished. These results provide a fundamental strategy to\ndesign high-performance chemical sensors with graphene functional blocks.",
        "positive": "Nonlinear response and crosstalk of electrically driven silicon spin\n  qubits: Micromagnet-based electric dipole spin resonance (EDSR) offers an attractive\npath for the near-term scaling of dense arrays of silicon spin qubits in\ngate-defined quantum dots while maintaining long coherence times and high\ncontrol fidelities. However, accurately controlling dense arrays of qubits\nusing a multiplexed drive will require an understanding of the crosstalk\nmechanisms that may reduce operational fidelity. We identify a novel crosstalk\nmechanism whereby the Rabi frequency of a driven qubit is drastically changed\nwhen the drive of an adjacent qubit is turned on. These observations raise\nimportant considerations for scaling single-qubit control."
    },
    {
        "anchor": "Stabilization and application of asymmetric N\u00e9el skyrmions in hybrid\n  nanostructures: Increasing amounts of information force the continuous improvement of\ninformation storage and processing technologies, further device\nminiaturization, and their efficiency increase. Magnetic skyrmions, topological\nquasiparticles, and the smallest stable magnetic textures possess intriguing\nproperties and potential for data storage applications. Hybrid nanostructures\nwith elements of different magnetization orientations can offer additional\nadvantages for developing skyrmion-based spintronic and magnonic devices. We\nshow that an N\\'eel-type skyrmion confined within a nanodot placed on top of a\nferromagnetic stripe produces a unique and compelling platform for exploring\nmutual coupling between magnetization textures. The skyrmion induces an imprint\nupon the stripe, which, in turn, asymmetrically squeezes the skyrmion in the\ndot, increasing their size and the range of skyrmion stability for small values\nof DMI, as well as introducing skyrmion bi-stability. At the end, we present a\nproof-of-concept technique for unconstrained transport of a skyrmion along a\nracetrack based on proposed hybrid systems. Our results demonstrate a hybrid\nstructure that is promising for applications in magnonics and spintronics.",
        "positive": "Nonlocal Exciton-Photon Interactions in Hybrid High-Q Beam Nanocavities\n  with Encapsulated MoS$_2$ Monolayers: Atomically thin semiconductors can be readily integrated into a wide range of\nnanophotonic architectures for applications in quantum photonics and novel\noptoelectronic devices. We report the observation of nonlocal interactions of\n\\textit{free} trions in pristine hBN/MoS$_2$/hBN heterostructures coupled to\nsingle mode (Q $>10^4$) quasi 0D nanocavities. The high excitonic and photonic\nquality of the interaction system stems from our integrated nanofabrication\napproach simultaneously with the hBN encapsulation and the maximized local\ncavity field amplitude within the MoS$_2$ monolayer. We observe a nonmonotonic\ntemperature dependence of the cavity-trion interaction strength, consistent\nwith the nonlocal light-matter interactions in which the extent of the\ncenter-of-mass wavefunction is comparable to the cavity mode volume in space.\nOur approach can be generalized to other optically active 2D materials, opening\nthe way towards harnessing novel light-matter interaction regimes for\napplications in quantum photonics."
    },
    {
        "anchor": "Dual Shapiro steps of a phase-slip junction in the presence of a\n  parasitic capacitance: Bloch oscillations in a single Josephson junction in the phase-slip regime\nrelate current to frequency. They can be measured by applying a periodic drive\nto a DC-biased, small Josephson junction. Phase-locking between the periodic\ndrive and the Bloch oscillations then gives rise to steps at constant current\nin the I-V curves, also known as dual Shapiro steps. Unlike conventional\nShapiro steps, a measurement of these dual Shapiro steps is impeded by the\npresence of a parasitic capacitance. This capacitance shunts the junction\nresulting in a suppression of the amplitude of the Bloch oscillations. This\ndetrimental effect of the parasitic capacitance can be remedied by an on-chip\nsuperinductance. Additionally, we introduce a large off-chip resistance to\nprovide the necessary dissipation. We investigate the resulting system by a set\nof analytical and numerical methods. In particular, we obtain an explicit\nanalytical expression for the height of dual Shapiro steps as a function of the\nratio of the parasitic capacitance to the superinductance. Using this result,\nwe provide a quantitative estimate of the dual Shapiro step height. Our\ncalculations reveal that even in the presence of a parasitic capacitance, it\nshould be possible to observe Bloch oscillations with realistic experimental\nparameters.",
        "positive": "The effect of Auger heating on intraband carrier relaxation in\n  semiconductor quantumrods: The rate at which excited charge carriers relax to their equilibrium state\naffects many aspects of the performance of nanoscale devices, including\nswitching speed, carrier mobility and luminescent efficiency. Better\nunderstanding of the processes that govern carrier relaxation therefore has\nimportant technological implications. A significant increase in carrier-carrier\ninteractions caused by strong spatial confinement of electronic excitations in\nsemiconductor nanostructures leads to a considerable enhancement of Auger\neffects, which can further result in unusual, Auger-process-controlled\nrecombination and energy-relaxation regimes. Here, we report the first\nexperimental observation of efficient Auger heating in CdSe quantum rods at\nhigh pump intensities, leading to a strong reduction of carrier cooling rates.\nIn this regime, the carrier temperature is determined by the balance between\nenergy outflow through phonon emission and energy inflow because of Auger\nheating. This equilibrium results in peculiar carrier cooling dynamics that\nclosely correlate with recombination dynamics, an effect never before seen in\nbulk or nanoscale semiconductors."
    },
    {
        "anchor": "Quantum-dot spin qubit and hyperfine interaction: We review our investigation of the spin dynamics for two electrons confined\nto a double quantum dot under the influence of the hyperfine interaction\nbetween the electron spins and the surrounding nuclei. Further we propose a\nscheme to narrow the distribution of difference in polarization between the two\ndots in order to suppress hyperfine induced decoherence.",
        "positive": "Transport, Aharonov-Bohm, and Topological Effects in Graphene Molecular\n  Junctions and Graphene Nanorings: The unique ultra-relativistic, massless, nature of electron states in\ntwo-dimensional extended graphene sheets, brought about by the honeycomb\nlattice arrangement of carbon atoms in two-dimensions, provides ingress to\nexplorations of fundamental physical phenomena in graphene nanostructures. Here\nwe explore the emergence of new behavior of electrons in atomically precise\nsegmented graphene nanoribbons (GNRs) and graphene rings with the use of\ntight-binding calculations, non-equilibrium Green's function transport theory,\nand a newly developed Dirac continuum model that absorbs the\nvalence-to-conductance energy gaps as position-dependent masses, including\ntopological-in-origin mass-barriers at the contacts between segments. Through\ntransport investigations in variable-width segmented GNRs with armchair,\nzigzag, and mixed edge terminations we uncover development of new\nFabry-Perot-like interference patterns in segmented GNRs, a crossover from the\nultra-relativistic massless regime, characteristic of extended graphene\nsystems, to a massive relativistic behavior in narrow armchair GNRs, and the\nemergence of nonrelativistic behavior in zigzag-terminated GNRs. Evaluation of\nthe electronic states in a polygonal graphene nanoring under the influence of\nan applied magnetic field in the Aharonov-Bohm regime, and their analysis with\nthe use of a relativistic quantum-field theoretical model, unveils development\nof a topological-in-origin zero-energy soliton state and charge\nfractionization. These results provide a unifying framework for analysis of\nelectronic states, coherent transport phenomena, and the interpretation of\nforthcoming experiments in segmented graphene nanoribbons and polygonal rings."
    },
    {
        "anchor": "Imprinting spatial helicity structure of vector vortex beam on spin\n  texture in semiconductors: We present the transfer of the spatially variant polarization of\ntopologically structured light to the spatial spin texture in a semiconductor\nquantum well. The electron spin texture, which is a circular pattern with\nrepeating spin-up and spin-down states whose repetition rate is determined by\nthe topological charge, is directly excited by a vector vortex beam with a\nspatial helicity structure. The generated spin texture efficiently evolves into\na helical spin wave pattern owing to the spin-orbit effective magnetic fields\nin the persistent spin helix state by controlling the spatial wave number of\nthe excited spin mode. By tuning the repetition length and azimuthal angle, we\nsimultaneously generate helical spin waves with opposite phases by a single\nbeam.",
        "positive": "Experimental investigation of the ratchet effect in a two-dimensional\n  electron system with broken spatial inversion symmetry: We report on experimental evidence of directed electron transport, induced by\nexternal linear-polarized microwave irradiation, in a two-dimensional\nspatially-periodic asymmetrical system called ratchet. The broken spatial\nsymmetry was introduced in a high mobility two-dimensional electron gas based\non AlGaAs/GaAs heterojunction, by patterning an array of artificial\nsemi-discs-shaped antidots. We show that the direction of the transport is\nefficiently changed by microwave polarization. The dependence of the effect on\nmagnetic field and temperature is investigated. This represents a significant\nstep towards the realization of new microwave detectors and current generators."
    },
    {
        "anchor": "State-dependent impedance of a strongly coupled oscillator-qubit system: We investigate the measurements of two-state quantum systems (qubits) at\nfinite temperatures using a resonant harmonic oscillator as a quantum probe.\nThe reduced density matrix and oscillator correlators are calculated by a\nscheme combining numerical methods with an analytical perturbation theory.\nCorrelators provide us information about the system impedance, which depends on\nthe qubit state. We show in detail how this property can be exploited in the\nqubit measurement.",
        "positive": "Small scale lateral superlattices in two-dimensional electron gases\n  prepared by diblock copolymer masks: A poly(styrene-block-methylmethacrylate) diblock copolymer in the hexagonal\ncylindrical phase has been used as a mask for preparing a periodic gate on top\nof a Ga[Al]As-heterostructure. A superlattice period of 43 nm could be imposed\nonto the two-dimensional electron gas. Transport measurements show a\ncharacteristic positive magnetoresistance around zero magnetic field which we\ninterpret as a signature of electron motion guided by the superlattice\npotential."
    },
    {
        "anchor": "Field Theoretical Approach To Quantum Hall Ferromagnets: We present a quantum field theoretical analysis of a $\\nu = 1$ quantum Hall\nsystem when the effective Land\\'e $g$ factor is small. We clearly demonstrate\nthat the ground state of the system is ferromagnetic. We note that it is the\nshort range component of the Coulomb interaction which is instrumental in\naligning the spins. We then go on to derive the effective lagrangian for the\nlowest lying spin excitations. At the leading order, apart from the usual O(3)\nsigma model terms, we find a term proportional to the Pontryagin density and a\nlong range Coulomb interaction term between these densities. Beyond the leading\norder in the derivative expansion, we find an interesting Chern-Simons term\nconstructed out of the basic spin variables. For low enough energies, however,\nwe notice that the effects of mixing of higher Landau levels is more important\nthan the next to leading terms in the derivative expansion. We provide a\nsystematic way of calculating these corrections.",
        "positive": "Enhancement of thermoelectric efficiency and violation of the\n  Wiedemann-Franz law due to Fano effect: We consider the thermoelectric properties of a double-quantum-dot molecule\ncoupled in parallel to metal electrodes with a magnetic flux threading the\nring. By means of the Sommerfeld expansion we obtain analytical expressions for\nthe electric and thermal conductances, thermopower and figure of merit for\narbitrary values of the magnetic flux. We neglect electronic correlations. The\nFano antiresonances in transmission demand that terms usually discarded in the\nSommerfeld expansion are taken into account. We also explore the behavior of\nthe Lorenz ratio L=\\kappa/\\sigma T, where \\kappa\\ and \\sigma\\ are the thermal\nand electrical conductances and T the absolute temperature, and we discuss the\nreasons why the Wiedemann-Franz law fails in presence of Fano antiresonances."
    },
    {
        "anchor": "Opportunities in Electrically Tunable 2D Materials Beyond Graphene:\n  Recent Progress and Future Outlook: The interest in two-dimensional and layered materials continues to expand,\ndriven by the compelling properties of individual atomic layers that can be\nstacked and/or twisted into synthetic heterostructures. The plethora of\nelectronic properties as well as the emergence of many different\nquasiparticles, including plasmons, polaritons, trions and excitons with large,\ntunable binding energies that all can be controlled and modulated through\nelectrical means has given rise to many device applications. In addition, these\nmaterials exhibit both room-temperature spin and valley polarization,\nmagnetism, superconductivity, piezoelectricity that are intricately dependent\non the composition, crystal structure, stacking, twist angle, layer number and\nphases of these materials. Initial results on graphene exfoliated from single\nbulk crystals motivated the development of wide-area, high purity synthesis and\nheterojunctions with atomically clean interfaces. Now by opening this design\nspace to new synthetic two-dimensional materials \"beyond graphene\", it is\npossible to explore uncharted opportunities in designing novel heterostructures\nfor electrical tunable devices. To fully reveal the emerging functionalities\nand opportunities of these atomically thin materials in practical applications,\nthis review highlights several representative and noteworthy research\ndirections in the use of electrical means to tune these aforementioned physical\nand structural properties, with an emphasis on discussing major applications of\nbeyond graphene 2D materials in tunable devices in the past few years and an\noutlook of what is to come in the next decade.",
        "positive": "Mid infrared near-field fingerprint spectroscopy of the 2D electron gas\n  in LaAlO$_3$/SrTiO$_3$ at low temperatures: Confined electron systems, such as 2D electron gases (2DEGs), 2D materials,\nor topological insulators show great technological promise but their\nsusceptibility to defects often results in nanoscale inhomogeneities with\nunclear origins. Scattering-type scanning near-field optical microscopy\n(s-SNOM) is useful to investigate buried confined electron systems\nnon-destructively with nanoscale resolution, however, a clear separation of\ncarrier concentration and mobility was often impossible in s-SNOM. Here, we\npredict a previously inaccessible characteristic \"fingerprint\" response of the\nprototypical LaAlO$_3$/SrTiO$_3$ 2DEG, and verify this using a state-of-the-art\ntunable narrow-band laser in mid-infrared cryo-s-SNOM at 8 K. Our modelling\nallows us to separate the influence of carrier concentration and mobility on\nfingerprint spectra and to characterize 2DEG inhomogeneities on the nanoscale.\nThis spatially resolved information about the local electronic properties can\nbe used to identify the origin of inhomogeneities in confined electron systems,\nmaking the s-SNOM fingerprint response a valuable tool for nanoelectronics and\nquantum technology."
    },
    {
        "anchor": "Sub-Threshold Field Emission from Thin Silicon Membranes: We report on strongly enhanced electron multiplication in thin silicon\nmembranes. The device is configured as a transmission-type membrane for\nelectron multiplication. A sub-threshold electric field applied on the emission\nside of the membrane enhances the number of electrons emitted by two orders of\nmagnitude. This enhancement stems from field emitted electrons stimulated by\nthe incident particles, which suggests that stacks of silicon membranes can\nform ultra-sensitive electron multipliers.",
        "positive": "Optimized proximity thermometer for ultrasensitive detection: Role of an\n  ohmic electromagnetic environment: We propose a mesoscopic thermometer for ultrasensitive detection based on the\nproximity effect in superconductor-normal metal (SN) heterostructures. The\ndevice is based on the zero-bias anomaly due to the inelastic Cooper pair\ntunneling in an SNIS junction (I stands for an insulator) coupled to an ohmic\nelectromagnetic (EM) environment. The theoretical model is done in the\nframework of the quasiclassical Usadel Green's formalism and the dynamical\nCoulomb blockade. The usage of an ohmic EM environment makes the thermometer\nhighly sensitive down to very low temperatures, $T \\lesssim 5~$mK. Moreover,\ndefined in this way, the thermometer is stable against small but nonvanishing\nvoltage amplitudes typically used for measuring the zero-bias differential\nconductance in experiments. Finally, we propose a simplified view, based on an\nanalytic treatment, which is in very good agreement with numerical results and\ncan serve as a tool for the development, calibration, and optimization of such\ndevices in future experiments in quantum calorimetry."
    },
    {
        "anchor": "Chiral Spin Textures of Strongly Interacting Particles in Quantum Dots: We probe for statistical and Coulomb induced spin textures among the\nlow-lying states of repulsively-interacting particles confined to potentials\nthat are both rotationally and time-reversal invariant. In particular, we focus\non two-dimensional quantum dots and employ configuration-interaction techniques\nto directly compute the correlated many-body eigenstates of the system. We\nproduce spatial maps of the single-particle charge and spin density and verify\nthe annular structure of the charge density and the rotational invariance of\nthe spin field. We further compute two-point spin correlations to determine the\ncorrelated structure of a single component of the spin vector field. In\naddition, we compute three-point spin correlation functions to uncover chiral\nstructures. We present evidence for both chiral and quasi-topological spin\ntextures within energetically degenerate subspaces in the three- and\nfour-particle system.",
        "positive": "Buttiker Probe Based Modeling of TDDB: Application to Dielectric\n  Breakdown in MTJs and MOS Devices: Dielectric layers are gradually being down-scaled in different electronic\ndevices like MOSFETs and Magnetic Tunnel Junctions (MTJ) with shrinking device\nsizes. As a result, time dependent dielectric breakdown (TDDB) has become a\nmajor issue in such devices. In this paper we propose a generalized way of\nmodeling the stress induced leakage current (SILC) and post breakdown current\n(PBC) due to time dependent wear-out of the dielectric layer. We model the\ntraps formed in dielectric layer using Buttiker probe and incorporate the\nButtiker probe self-energies in standard self-consistent Non-Equilibrium Green\nFunction (NEGF) formalism in order to determine SILC and PBC. In addition, we\nhave shown the impact of break down in the dielectric layer on the spin current\nand spin filtering characteristics of an MTJ. The proposed model is generic in\nnature. It can be extended from MTJs and conventional CMOS technology to any\nother devices with any type of single and multiple layers of dielectric\nmaterial(s)."
    },
    {
        "anchor": "Switchable polar spirals in tricolor oxide superlattices: There are increasing evidences that ferroelectric states at the nanoscale can\nexhibit fascinating topological structures including polar vortices and\nskyrmions,akin to those observed in the ferromagnetic systems. Here we report\nthe discovery of a new type of polar topological structure,ordered array of\nnanoscale spirals in the tricolor ferroelectric superlattice system via phase\nfield simulations. This polar spiral structure is composed of fine ordered\nsemivortex arrays with vortex cores forming a wavy distribution. It is\ndemonstrated that this tricolor system has an ultrahigh Curie temperature of\n1000 K and a temperature of 650 K for the phase transformation from spiral\nstructure to inplane orthorhombic domain structure, showing a greatly enhanced\nthermal stability than the recently discovered polar vortex lattices in the\nsuperlattice system. Moreover, the spiral structure has a net inplane\npolarization that could be switched by an experimentally feasible irrotational\ninplane field. The switching process involves a metastable vortex state, and is\nfully reversible.",
        "positive": "Gate-tunable spatial modulation of localized plasmon resonances: Nanoplasmonics exploits the coupling between light and collective electron\ndensity oscillations (plasmons) to bypass the stringent limits imposed by\ndiffraction. This coupling enables confinement of light to sub-wavelength\nvolumes and is usually exploited in nanostructured metals. Substantial efforts\nare being made at the current frontier of the field to employ electron systems\nin semiconducting and semimetallic materials since these add the exciting\npossibility of realizing electrically tunable and/or active nanoplasmonic\ndevices. Here we demonstrate that a suitable design of the doping profile in a\nsemiconductor nanowire (NW) can be used to tailor the plasmonic response and\ninduce localization effects akin to those observed in metal nanoparticles.\nMoreover, by field-effect carrier modulation, we demonstrate that these\nlocalized plasmon resonances can be spatially displaced along the nanostructure\nbody, thereby paving the way for the implementation of spatially tunable\nplasmonic circuits."
    },
    {
        "anchor": "Topological quantum quench dynamics carrying arbitrary Hopf and\n  second-Chern numbers: A quantum quench is a nonequilibrium dynamics governed by the unitary\nevolution. We propose a two-band model whose quench dynamics is characterized\nby an arbitrary Hopf number belonging to the homotopy group $\\pi\n_{3}(S^{2})=\\mathbb{Z}$. When we quench a system from an insulator with the\nChern number $C_{i}\\in \\pi _{2}(S^{2})=\\mathbb{Z}$ to another insulator with\nthe Chern number $C_{f} $, the preimage of the Hamiltonian vector forms links\nhaving the Hopf number $C_{f}-C_{i}$. We also investigate a quantum-quench\ndynamics for a four-band model carrying an arbitrary second-Chern number $N\\in\n\\pi _{4}(S^{4})=\\mathbb{Z}$, which can be realized by quenching a\nthree-dimensional topological insulator having the three-dimensional winding\nnumber $N\\in \\pi _{3}(S^{3})=\\mathbb{Z}$.",
        "positive": "Thermoelectric Transport through a Quantum Dot: Effects of Kondo\n  Channels Asymmetry: We consider effects of magnetic field on the thermopower and\nthermoconductance of a single-electron transistor based on a quantum dot\nstrongly coupled to one of the leads by a single-mode quantum point contact. We\nshow appearance of two new energy scales: T_{min} ~ |r|^2 E_C(B/B_C)^2\ndepending on a ratio of magnetic field B and the field B_C corresponding to a\nfull polarization of point contact and T_{max} ~ |r|^2 E_C depending on a\nreflection amplitude r and charging energy E_C. We predict that the behavior of\nthermoelectric coefficients is consistent with the Fermi-liquid theory at\ntemperatures T << T_{min}, while crossover from Non-Fermi-liquid regime\nassociated with a two-channel Kondo effect to Fermi-liquid single-channel Kondo\nbehavior can be seen at T_{min}<T<T_{max}."
    },
    {
        "anchor": "Parity Effect and Charge Binding Transition in Submicron Josephson\n  Junction Arrays: We reconsider the issue of Berezinskii-Kosterlitz-Thouless (BKT) transition\ninto an insulating state in the Coulomb-dominated Josephson junction arrays. We\nshow that previously predicted picture of the Cooper-pair BKT transtion at T =\nT_2 is valid only under the condition that T_2 is considerably below the\nparity-effect temperature (which is usually almost 10 times below the value of\nsuperconductive transition temperature), and even in this case it is not a\nrigorous phase transition but only a crossover, whereas the real phase\ntransition takes place at T_1 = T_2/4. Our theory is in agreement with\navailable experimental data on Coulomb-dominated Josephson arrays and also\nsheds some light on the origin of unusual reentrant temperature dependence of\nresistivity in the array with nearly-criticial ratio of Coulomb to Josephson\nenergies.",
        "positive": "Graphene Nanogap for Gate Tunable Quantum Coherent Single Molecule\n  Electronics: We present atomistic calculations of quantum coherent electron transport\nthrough fulleropyrrolidine terminated molecules bridging a graphene nanogap. We\npredict that three difficult problems in molecular electronics with single\nmolecules may be solved by utilizing graphene contacts: (1) a back gate\nmodulating the Fermi level in the graphene leads facilitate control of the\ndevice conductance in a transistor effect with high on/off current ratio; (2)\nthe size mismatch between leads and molecule is avoided, in contrast to the\ntraditional metal contacts; (3) as a consequence, distinct features in charge\nflow patterns throughout the device are directly detectable by scanning\ntechniques. We show that moderate graphene edge disorder is unimportant for the\ntransistor function."
    },
    {
        "anchor": "Spin-relaxation time in the impurity band of wurtzite semiconductors: The spin-relaxation time for electrons in the impurity band of semiconductors\nwith wurtzite crystal structure is determined. The effective Dresselhaus\nspin-orbit interaction Hamiltonian is taken as the source of the spin\nrelaxation at low temperature and for doping densities corresponding to the\nmetallic side of the metal-insulator transition. The spin-flip hopping matrix\nelements between impurity states are calculated and used to set up a\ntight-binding Hamiltonian that incorporates the symmetries of wurtzite\nsemiconductors. The spin-relaxation time is obtained from a semiclassical model\nof spin diffusion, as well as from a microscopic self-consistent diagrammatic\ntheory of spin and charge diffusion in doped semiconductors. Estimates are\nprovided for particularly important materials. The theoretical spin-relaxation\ntimes compare favorably with the corresponding low-temperature measurements in\nGaN and ZnO. For InN and AlN, we predict that tuning of the spin-orbit coupling\nconstant induced by an external potential leads to a potentially dramatic\nincrease of the spin-relaxation time related to the mechanism under study.",
        "positive": "Hall Drag in Correlated Double Layer Quantum Hall Systems: We show that in the limit of zero temperature, double layer quantum Hall\nsystems exhibit a novel phenomena called Hall drag, namely a current driven in\none layer induces a voltage drop in the other layer, in the direction\nperpendicular to the driving current. The two-by-two Hall resistivity tensor is\nquantized and proportional to the ${\\bf K}$ matrix that describes the\ntopological order of the quantum Hall state, even when the ${\\bf K}$ matrix\ncontains a zero eigenvalue, in which case the Hall conductivity tensor does not\nexist. Relation between the present work and previous ones is also discussed."
    },
    {
        "anchor": "Emergent topological quasiparticle kinetics in constricted nanomagnets: The ubiquitous domain wall kinetics under magnetic field or current\napplication describes the dynamic properties in nanostructured magnets.\nHowever, when the geometrical size of a nanomagnetic system is constricted to\nthe limiting domain wall length scale, the competing energetics between\nanisotropy, exchange and dipolar interactions can cause emergent kinetics due\nto quasiparticle relaxation, similar to bulk magnets of atomic origin. Here, we\npresent a joint experimental and theoretical study to support this argument --\nconstricted nanomagnets, made of antiferromagnetic and paramagnetic neodymium\nthin film with honeycomb motif, reveal fast kinetic events at ps time scales\ndue to the relaxation of chiral vortex loop-shaped topological quasiparticles\nthat persist to low temperature in the absence of any external stimuli. Such\nphenomena are typically found in macroscopic magnetic materials. Our discovery\nis especially important considering the fact that paramagnets or\nantiferromagnets have no net magnetization. Yet, the kinetics in neodymium\nnanostructures is quantitatively similar to that found in ferromagnetic\ncounterparts and only varies with the thickness of the specimen. This suggests\nthat a universal, topological quasiparticle mediated dynamical behavior can be\nprevalent in nanoscopic magnets, irrespective of the nature of underlying\nmagnetic material.",
        "positive": "Photoluminescence of high-density exciton-polariton condensates: We examine the photoluminescence of highly-excited exciton-polariton\ncondensates in semiconductor microcavities. Under strong pumping,\nexciton-polariton condensates have been observed to undergo a lasing transition\nwhere strong coupling between the excitons and photons is lost. We discuss an\nalternative high-density scenario, where the strong coupling is maintained. We\nfind that the photoluminescence smoothly transitions between the lower\npolariton energy to the cavity photon energy. An intuitive understanding of the\nchange in spectral characteristics is given, as well as differences to the\nphotoluminescence characteristics of the lasing case."
    },
    {
        "anchor": "Feedback stabilization of pure states in quantum transport: We propose a feedback control scheme for generating and stabilizing pure\nstates of transport devices, such as charge qubits, under non-equilibrium\nconditions. The purification of the device state is conditioned on single\nelectron jumps and leaves a clear signal in the full counting statistics which\ncan be used to optimize control parameters. As an example of our control\nscheme, we are presenting the stabilization pure transport states in a double\nquantum dot setup with the inclusion of phonon dephasing.",
        "positive": "Kinetic orbital moments and nonlocal transport in disordered metals with\n  nontrivial geometry: We study the effects of spatial dispersion in disordered noncentrosymmetric\nmetals. These include the kinetic magnetoelectric effect, natural optical\nactivity of metals, as well as the so-called dynamic chiral magnetic effect as\na particular case of the latter. These effects are determined by the linear in\nthe wave vector of an electromagnetic perturbation contribution to the\nconductivity tensor of a material, and stem from the magnetic moments of\nquasiparticles near the Fermi surface. We identify new disorder-induced\ncontributions to these magnetic moments that come from the skew scattering and\nside jump processes, familiar from the theory of anomalous Hall effect. We show\nthat at low frequencies the spatial dispersion of the conductivity tensor comes\nmainly either from the skew scattering or intrinsic contribution, and there is\nalways a region of frequencies in which the intrinsic mechanism dominates. Our\nresults imply that in clean three-dimensional metals, current-induced\nmagnetization is in general determined by impurity skew scattering, rather than\nintrinsic contributions. Intrinsic effects are expected to dominate in cubic\nenantiomorphic crystals with point groups $T$ and $O$, and in polycrystalline\nsamples, regardless of their mobility."
    },
    {
        "anchor": "Topological Nonsymmorphic Ribbons out of Symmorphic Bulk: States of matter with nontrivial topology have been classified by their bulk\nsymmetry properties. However, by cutting the topological insulator into\nribbons, the symmetry of the system is reduced. By constructing effective\nHamiltonians containing the proper symmetry of the ribbon, we find that the\nnature of topological states is dependent on the reduced symmetry of the ribbon\nand the appropriate boundary conditions. We apply our model to the recently\ndiscovered two-dimensional topological crystalline insulators composed by IV-VI\nmonolayers, where we verify that the edge terminations play a major role on the\nDirac crossings. Particularly, we find that some bulk cuts lead to\nnonsymmorphic ribbons, even though the bulk material is symmorphic. The\nnonsymmorphism yields a new topological protection, where the Dirac cone is\npreserved for arbitrary ribbon width. The effective Hamiltonians are in good\nagreement with ab initio calculations.",
        "positive": "Evolution of electric-field-induced quasibound states and resonances in\n  one-dimensional open quantum systems: A comparative analysis of three different time-independent approaches to\nstudying open quantum structures in uniform electric field $\\mathscr{E}$ was\nperformed using the example of one-dimensional attractive or repulsive\n$\\delta$-potential and surface that supports the Robin boundary condition. The\nthree considered methods exploit different properties of the scattering matrix\n$S(\\mathscr{E};E)$ as a function of energy $E$: its poles, real values, and\nzeros of the second derivative of its phase. The essential feature of the\nmethod of zeroing the resolvent, which produces complex energies, is the\nunlimited growth of the wave function at infinity, which is, however,\neliminated by the time-dependent interpretation. The real energies at which the\nunitary scattering matrix becomes real correspond to the largest possible\ndistortion, $S=+1$, or its absence at $S=-1$ which in either case leads to the\nformation of quasibound states. Depending on their response to increasing\nelectric intensity, two types of field-induced positive energy quasibound\nlevels are identified: electron- and hole-like states. Their evolution and\ninteraction in enlarging field lead ultimately to the coalescence of pairs of\nopposite states, with concomitant divergence of the associated dipole moments\nin what is construed as an electric breakdown of the structure. The\ncharacteristic features of the coalescence fields and energies are calculated\nand the behavior of the levels in their vicinity is analyzed. Similarities\nbetween the different approaches and their peculiarities are highlighted; in\nparticular, for zero-field bound state in limit of vanishing $\\mathscr{E}$, all\nthree methods produce same results, with their outcomes deviating from each\nother according to growing electric intensity."
    },
    {
        "anchor": "Ultrafast charge-transfer exciton dynamics in C$_{60}$ thin films: The high flexibility of organic molecules offers great potential for\ndesigning the optical properties of light-active materials for the next\ngeneration of optoelectronic and photonic applications. However, despite\nsuccessful implementations of molecular materials in todays' display and\nphotovoltaic technology, many fundamental aspects of the light-to-charge\nconversion have still to be uncovered. Here, we focus on the ultrafast dynamics\nof optically excited excitons in C$_{60}$ thin films depending on the molecular\ncoverage and the light-polarization of the optical excitons. Using time- and\nmomentum-resolved photoemission with fs-XUV radiation, we follow the\ndepopulation dynamics in the excited states while simultaneously monitoring the\nsignatures of the excitonic charge character in the molecular valence states.\nOptical excitation with visible light results in the instantaneous formation of\ncharge-transfer (CT) excitons, which transform stepwise into energetically\nlower Frenkel-like excitons. While the number and energetic position of energy\nlevels within this cascade process are independent of the molecular coverage\nand the light polarization of the optical excitation, we find quantitative\ndifferences in the depopulation times and the optical excitation efficiency.\nOur comprehensive study reveals the crucial role of CT excitons for the excited\nstate dynamics of homo-molecular fullerene materials and thin films.",
        "positive": "Tunable Graphene System with Two Decoupled Monolayers: The use of two truly two-dimensional gapless semiconductors, monolayer and\nbilayer graphene, as current-carrying components in field-effect transistors\n(FET) gives access to new types of nanoelectronic devices. Here, we report on\nthe development of graphene-based FETs containing two decoupled graphene\nmonolayers manufactured from a single one folded during the exfoliation\nprocess. The transport characteristics of these newly-developed devices differ\nmarkedly from those manufactured from a single-crystal bilayer. By analyzing\nShubnikov-de Haas oscillations, we demonstrate the possibility to independently\ncontrol the carrier densities in both layers using top and bottom gates,\ndespite there being only a nano-meter scale separation between them."
    },
    {
        "anchor": "Long nuclear spin decay times controlled by optical pumping in\n  individual quantum dots: Nuclear polarization dynamics are measured in the nuclear spin bi-stability\nregime in a single optically pumped InGaAs/GaAs quantum dot. The controlling\nrole of nuclear spin diffusion from the dot into the surrounding material is\nrevealed in pump-probe measurements of the non-linear nuclear spin dynamics. We\nmeasure nuclear spin decay times in the range 0.2-5 sec, strongly dependent on\nthe optical pumping time. The long nuclear spin decay arises from polarization\nof the material surrounding the dot by spin diffusion for long (>5sec) pumping\ntimes. The time-resolved methods allow the detection of the unstable nuclear\npolarization state in the bi-stability regime otherwise undetectable in cw\nexperiments.",
        "positive": "Detecting Gapless Excitations above Ferromagnetic Domain Walls: In a two or three dimensional ferromagnetic XXZ model, a low energy\nexcitation mode above a magnetic domain wall is gapless, whereas all of the\nusual spin wave excitations moving around the whole crystal are gapful.\nAlthough this surprising fact was already proved in a mathematically rigorous\nmanner, the gapless excitations have not yet been detected experimentally. For\nthis issue, we show theoretically that the gapless excitations appear as the\ndynamical fluctuations of the experimental observable, magnetoresistance, in a\nferromagnetic wire. We also discuss other methods (e.g., ferromagnetic\nresonance and neutron scattering) to detect the gapless excitations\nexperimentally."
    },
    {
        "anchor": "Reflection of nanoparticles: This work is devoted to molecular dynamics modeling of collision of\nnanoparticle having a small number of degrees of freedom with a structureless\nplain. The new regularities are established that determine properties of such\nparticles. Generalized collision law is obtained where particle properties are\ndetermined by two coefficient, on of which corresponds to restitution\ncoefficient. The discovered regularity predicts the existence of anomalous mode\nof particle reflection from a massive plain. In this mode, velocity of\nnanoparticle after reflection from a plain can exceed the initial one. The\ncriterion of realization of such mode is obtained. Anomalous collision mode was\nobserved during numerical modeling. Physical mechanism are discussed of\nphenomena that are observed during numerical experiments.",
        "positive": "Anisotropic magneto-optical absorption and linear dichroism in\n  two-dimensional semi-Dirac electron systems: We present a theoretical study on the Landau levels (LLs) and magneto-optical\nabsorption of a two-dimensional semi-Dirac electron system under a\nperpendicular magnetic field. Based on an effective k.p Hamiltonian, we find\nthat the LLs are proportional to the two-thirds power law of the magnetic field\nand level index, which can be understood as a hybridization of the LL of\nSchrodinger and Dirac electrons with new features. With the help of Kubo\nformula, we find the selection rule for interband (intraband) magneto-optical\ntransition is anisotropic (isotropic). Specifically, the selection rules for\ninterband magneto-optical transitions are $\\Delta n$=0, $\\pm2$ ($\\pm2$, $\\pm4$)\nfor linearly polarized light along the linear (parabolic) dispersion direction,\nwhile the selection rules for the intraband transition are $\\Delta n$=$\\pm1$,\n$\\pm3$ regardless of the polarization direction of the light. Further, the\nmagneto-optical conductivity for interband (intraband) transition excited by\nlinearly polarized light along the linear dispersion direction is two (one)\norders of magnitude larger than that along the parabolic dispersion direction.\nThis anisotropic magneto-optical absorption spectrum clearly reflects the\nstructure of the LLs, and results in a strong linear dichroism. Importantly, a\nperfect linear dichroism with magnetic-field tunable wavelength can be achieved\nby using the interband transition between the two lowest LLs, i.e, from Ev0 to\nEc0. Our results shed light on the magneto-optical property of the two\ndimensional semi-Dirac electron systems and pave the way to design magnetically\ncontrolled optical devices."
    },
    {
        "anchor": "Spin-noise in the anisotropic central spin model: Spin-noise measurements can serve as direct probe for the microscopic\ndecoherence mechanism of an electronic spin in semiconductor quantum dots\n(QD).We have calculated the spin-noise spectrum in the anisotropic central spin\nmodel using a Chebyshev expansion technique which exactly accounts for the\ndynamics up to an arbitrary long but fixed time in a finite size system. In the\nisotropic case, describing QD charged with a single electron, the short-time\ndynamics is in good agreement with a quasi-static approximation for the\nthermodynamic limit. The spin-noise spectrum, however, shows strong deviations\nat low frequencies with a power-law behavior. In the Ising limit, applicable to\nQDs with heavy-hole spins, the spin-noise spectrum exhibits a threshold\nbehavior above the Larmor frequency. In the generic anisotropic central spin\nmodel we have found a crossover from a Gaussian type of spin-noise spectrum to\na more Ising-type spectrum with increasing anisotropy in a finite magnetic\nfield. In order to make contact with experiments, we present ensemble averaged\nspin-noise spectra for QD ensembles charged with single electrons or holes. The\nGaussian-type noise spectrum evolves to a more Lorentzian shape spectrum with\nincreasing spread of characteristic time-scales and g-factors of the individual\nQDs.",
        "positive": "Fermi gas energetics in low-dimensional metals of spessial geometry: Changes in the metal properties, caused by periodic indents in the metal\nsurface, have been studied within the limit of quantum theory of free\nelectrons. It was shown that due to destructive interference of de Broglie\nwaves, some quantum states inside the low-dimensional metal become quantum\nmechanically forbidden for free electrons. Wave vector density in k space,\nreduce dramatically. At the same time, number of free electrons does not\nchange, as metal remains electrically neutral. Because of Pauli exclusion\nprinciple some free electrons have to occupy quantum states with higher wave\nnumbers. Fermi vector and Fermi energy of low-dimensional metal increase and\nconsequently its work function decrease. In experiment, magnitude of the effect\nis limited by the roughness of metal surface. Rough surface causes scattering\nof the de Broglie waves and compromise their interference. Recent experiments\ndemonstrated reduction of work function in thin metal films, having periodic\nindents in the surface. Experimental results are in good qualitative agreement\nwith the theory. This effect could exist in any quantum system comprising\nfermions inside a potential energy box of special geometry."
    },
    {
        "anchor": "Quantum charge pumping through resonant crossed Andreev reflection in\n  superconducting hybrid junction of Silicene: We theoretically investigate the phenomena of adiabatic quantum charge\npumping through a normal-insulator-superconductor-insulator-normal (NISIN)\nsetup of silicene within the scattering matrix formalism. Assuming thin barrier\nlimit, we consider the strength of the two barriers ($\\chi_{1}$ and $\\chi_{2}$)\nas the two pumping parameters in the adiabatic regime. Within this geometry, we\nobtain crossed Andreev reflection (CAR) with probability unity in the\n$\\chi_{1}$-$\\chi_{2}$ plane without concomitant transmission or elastic\ncotunneling (CT). Tunability of the band gap at the Dirac point by applying an\nexternal electric field perpendicular to the silicene sheet and variation of\nthe chemical potential at the normal silicene region, open up the possibility\nof achieving perfect either CAR or transmission process through our setup. This\nresonant behavior is periodic with the barrier strengths. We analyze the\nbehavior of the pumped charge through the NISIN structure as a function of the\npumping strength and angles of the incident electrons. We show that large\n($Q\\sim2e$) pumped charge can be obtained through our geometry when the pumping\ncontour encloses either the CAR or transmission resonance in the pumping\nparameter space. We discuss possible experimental feasibility of our\ntheoretical predictions.",
        "positive": "Large magnetoresistance dips and perfect spin-valley filter induced by\n  topological phase transitions in silicene: Spin-valley transport and magnetoresistance are investigated in\nsilicene-based N/TB/N/TB/N junction where N and TB are normal silicene and\ntopological barriers. The topological phase transitions in TB's are controlled\nby electric, exchange fields and circularly polarized light. As a result, we\nfind that by applying electric and exchange fields, four groups of spin-valley\ncurrents are perfectly filtered, directly induced by topological phase\ntransitions. Control of currents, carried by single, double and triple channels\nof spin-valley electrons in silicene junction, may be achievable by adjusting\nmagnitudes of electric, exchange fields and circularly polarized light. We may\nidentify that the key factor behind the spin-valley current filtered at the\ntransition points may be due to zero and non-zero Chern numbers. Electrons that\nare allowed to transport at the transition points must obey zero-Chern number\nwhich is equivalent to zero mass and zero-Berry's curvature, while electrons\nwith non-zero Chern number are perfectly suppressed. Very large\nmagnetoresistance dips are found directly induced by topological phase\ntransition points. Our study also discusses the effect of spin-valley dependent\nHall conductivity at the transition points on ballistic transport and reveals\nthe potential of silicene as a topological material for spin-valleytronics."
    },
    {
        "anchor": "Observation of the spin-polarized surface state in a noncentrosymmetric\n  superconductor BiPd: Recently, noncentrosymmetric superconductor BiPd has attracted considerable\nresearch interest due to the possibility of hosting topological\nsuperconductivity. Here we report a systematic high-resolution angle-resolved\nphotoemission spectroscopy (ARPES) and spin-resolved ARPES study of the normal\nstate electronic and spin properties of BiPd. Our experimental results show the\npresence of a surface state at higher-binding energy with the location of Dirac\npoint at around 700 meV below the Fermi level. The detailed photon energy,\ntemperature-dependent and spin-resolved ARPES measurements complemented by our\nfirst principles calculations demonstrate the existence of the spin polarized\nsurface states at high-binding energy. The absence of such spin-polarized\nsurface states near the Fermi level negates the possibility of a topological\nsuperconducting behavior on the surface. Our direct experimental observation of\nspin-polarized surface states in BiPd provides critical information that will\nguide the future search for topological superconductivity in noncentrosymmetric\nmaterials.",
        "positive": "Cooperative effects and disorder: A scaling analysis of the spectrum of\n  the effective atomic Hamiltonian: We study numerically the spectrum of the non-Hermitian effective Hamiltonian\nthat describes the dipolar interaction of a gas of $N\\gg 1$ atoms with the\nradiation field. We analyze the interplay between cooperative effects and\ndisorder for both scalar and vectorial radiation fields. We show that for dense\ngases, the resonance width distribution follows, both in the scalar and\nvectorial cases, a power law $P(\\Gamma) \\sim \\Gamma^{-4/3}$ that originates\nfrom cooperative effects between more than two atoms. This power law is\ndifferent from the $ P(\\Gamma) \\sim \\Gamma^{-1}$ behavior, which has been\nconsidered as a signature of Anderson localization of light in random systems.\nWe show that in dilute clouds, the center of the energy distribution is\ndescribed by Wigner's semicircle law in the scalar and vectorial cases. For\ndense gases, this law is replaced in the vectorial case by the Laplace\ndistribution. Finally, we show that in the scalar case the degree of resonance\noverlap increases as a power law of the system size for dilute gases, but\ndecays exponentially with the system size for dense clouds."
    },
    {
        "anchor": "Resonant tunneling in graphene-ferroelectric-graphene junctions: We study tunnel junctions consisting of a two-dimensional ferroelectric (FE)\nmaterial sandwiched between graphene electrodes. We formulate a theory for the\ninterplay of the FE polarization and induced free charges in such devices,\ntaking into account quantum capacitance effects. We predict a gate-sensitive FE\nvoltage difference across the device, which can be measured using electrostatic\nforce microscopy. Incorporating this electrostatic theory in the tunneling\ncurrent-voltage characteristics, we identify a resonance peak associated with\naligned Dirac cones as a highly sensitive probe of the FE polarization of the\njunction. This opens the way for device applications with few atom-thick FE\nlayers acting as readable ultra-high-density memory.",
        "positive": "Surface plasmon resonance of Cu nanowires in polycarbonate template: The Cu nanowires were electrodeposited in polycarbonate track-etched (PCT)\nmembrane. SEM, TEM and XPS techniques were used to characterize the morphology,\nstructure and size of nanowires as well as chemical Composition. The absorption\nspectrum of copper nanowires embedded in PCT was measured and calculated for\ndifferent incident angles and wavelengths. Our results showed that there is a\nbroad peak due to excitation surface plasmon at {\\theta} = 70\\degree for\nwavelength {\\lambda}= 730 nm. We applied the transfer matrix method and\nBruggeman homogenization formalism for optical modeling. The results of\nabsorption spectra showed that exist good agreement between the experimental\nand our used model. The results of this work may be useful in study of surface\nplasmon resonance of copper nanowires."
    },
    {
        "anchor": "Mode-sensitive magnetoelastic coupling in phononic-crystal\n  magnomechanics: Acoustically driven spin-wave resonance in a phononic crystal cavity is\nnumerically investigated. The designed cavity enables confinement of gigahertz\nvibrations in a wavelength-scale point-defect structure and sustains a variety\nof resonance modes. Inhomogeneous strain distributions in the modes modify the\nmagnetostrictive coupling and the spin-wave excitation susceptible to an\nexternal field orientation. In particular, a monopole-like mode in the cavity\nhaving a near-symmetrical pattern shows a subwavelength-scale mode volume and\ncan provide a versatile acoustic excitation scheme independent on field-angle\nvariation. Thus, the phononic-crystal platform offers an alternative approach\nto acoustically control the spin-wave dynamics with ultrasmall and\ninhomogeneous mode structures, which will be a key technology to integrate and\noperate large-scale magnomechanical circuits.",
        "positive": "Probing Quantum Phase Transitions on a Spin Chain with a Double Quantum\n  Dot: Quantum phase transitions (QPTs) in qubit systems are known to produce\nsingularities in the entanglement, which could in turn be used to probe the\nQPT. Current proposals to measure the entanglement are challenging however,\nbecause of their nonlocal nature. Here we show that a double quantum dot\ncoupled locally to a spin chain provides an alternative and efficient probe of\nQPTs. We propose an experiment to observe a QPT in a triple dot, based on the\nwell-known singlet projection technique."
    },
    {
        "anchor": "Confining and repulsive potentials from effective non-Abelian gauge\n  fields in graphene bilayers: We investigate the effect of shear and strain in graphene bilayers, under\nconditions where the distortion of the lattice gives rise to a smooth\none-dimensional modulation in the stacking sequence of the bilayer. We show\nthat strain and shear produce characteristic Moir\\'e patterns which can have\nthe same visual appearance on a large scale, but representing graphene bilayers\nwith quite different electronic properties. The different features in the\nlow-energy electronic bands can be ascribed to the effect of a fictitious\nnon-Abelian gauge field mimicking the smooth modulation of the stacking order.\nStrained and sheared bilayers show a complementary behavior, which can be\nunderstood from the fact that the non-Abelian gauge field acts as a repulsive\ninteraction in the former, expelling the electron density away from the\nstacking domain walls, while behaving as a confining interaction leading to\nlocalization of the electronic states in the sheared bilayers. In this latter\ncase, the presence of the effective gauge field explains the development of\nalmost flat low-energy bands, resembling the form of the zeroth Landau level\ncharacteristic of a Dirac fermion field. The estimate of the gauge field\nstrength in those systems gives a magnitude of the order of several tens of\nTesla, implying a robust phenomenology that should be susceptible of being\nobserved in suitably distorted bilayer samples.",
        "positive": "Nonlinear thermovoltage and thermocurrent in quantum dots: Quantum dots are model systems for quantum thermoelectric behavior because of\nthe ability to control and measure the effects of electron-energy filtering and\nquantum confinement on thermoelectric properties. Interestingly, nonlinear\nthermoelectric properties of such small systems can modify the efficiency of\nthermoelectric power conversion. Using quantum dots embedded in semiconductor\nnanowires, we measure thermovoltage and thermocurrent that are strongly\nnonlinear in the applied thermal bias. We show that most of the observed\nnonlinear effects can be understood in terms of a renormalization of the\nquantum-dot energy levels as a function of applied thermal bias and provide a\ntheoretical model of the nonlinear thermovoltage taking renormalization into\naccount. Furthermore, we propose a theory that explains a possible source of\nthe observed, pronounced renormalization effect by the melting of Kondo\ncorrelations in the mixed-valence regime. The ability to control nonlinear\nthermoelectric behavior expands the range in which quantum thermoelectric\neffects may be used for efficient energy conversion."
    },
    {
        "anchor": "Edge State Magnetism of Single Layer Graphene Nanostructures: We study edge state magnetism in graphene nanostructures using a mean field\ntheory of the Hubbard model. We investigate how the magnetism of the zigzag\nedges of graphene is affected by the presence of other types of terminating\nedges and defects. By a detailed study of both regular shapes, such as\npolygonal nanodots and nanoribbons, and irregular shapes, we conclude that the\nmagnetism in zigzag edges is very robust. Our calculations show that the zigzag\nedges that are longer than three to four repeat units are always magnetic,\nirrespective of other edges, regular or irregular. We, therefore, clearly\ndemonstrate that the edge irregularities and defects of the bounding edges of\ngraphene nanostructures does not destroy the edge state magnetism.",
        "positive": "Statistical properties of the critical eigenstates in power-law random\n  banded matrices across the band: The level-spacing distribution in the tails of the eigenvalue bands of the\npower-law random banded matrix (PRBM) ensemble have been investigated\nnumerically. The change of level-spacing statistics across the band is examined\nfor different coupling strengths and compared to the density of states for the\ndifferent systems. It is confirmed that, by varying the eigenvalue region, the\nsame level-spacing statistics can be reached as by varying the coupling\nstrength."
    },
    {
        "anchor": "Spin-orbit field switching of magnetization in ferromagnetic films with\n  perpendicular anisotropy: As an alternative to conventional magnetic field, the effective spin-orbit\nfield in transition metals, derived from the Rashba field experienced by\nitinerant electrons confined in a spatial inversion asymmetric plane through\nthe s-d exchange interaction, is proposed for the manipulation of\nmagnetization. Magnetization switching in ferromagnetic thin films with\nperpendicular magnetocrystalline anisotropy can be achieved by current induced\nspin-orbit field, with small in-plane applied magnetic field. Spin-orbit field\ninduced by current pulses as short as 10 ps can initiate ultrafast\nmagnetization switching effectively, with experimentally achievable current\ndensities. The whole switching process completes in about 100 ps.",
        "positive": "Layered Opposite Rashba Spin-Orbit Coupling in Bilayer Graphene: Loss of\n  Spin Chirality, Symmetry Breaking and Topological Transition: Inversion symmetry in bilayer graphene allows for layered opposite Rashba\nspin-orbit coupling (LO-RSOC) -- the situation when the RSOC has the same\nmagnitude but the opposite sign in two coupled spatially separated layers. We\nshow that the LO-RSOC results in the loss of spin chirality in the momentum\nspace, in contrast to the common uniform RSOC. This chirality loss makes it\ndifficult to experimentally establish whether the LO-RSOC (on the scale of 10\nmeV) exists, because the band structure is insensitive to it. To solve this\nproblem, we propose to identify the LO-RSOC either by gating to break the\ninversion symmetry or by magnetic field to break the time-reversal symmetry.\nRemarkably, we observe the transition between trivial and non-trivial band\ntopology as the system deviates from the LO Rashba state. Ab inito calculations\nsuggest that bilayer graphene encapsulated by two monolayers of Au is a\ncandidate to be a LO Rashba system."
    },
    {
        "anchor": "Effects of Polariton Energy Renormalisation in the Microcavity Optical\n  Parametric Oscillator: The CW microcavity optical parametric oscillator (OPO) state is investigated\nusing a theoretical treatment which includes the contributions of the pump,\nsignal and idler populations to the renormalisation of the polariton energies\n(the `blue-shift'). The theory predicts the pumping conditions under which the\nOPO switches on, showing that a pump angle > 10 degrees is required, but there\nis no particular significance to the `magic-angle' where pump, signal and idler\nare all on resonance. The signal and idler renormalisation contributions also\ncauses the signal emission to be driven towards the normal direction as the\npump power increases above threshold.",
        "positive": "Quantum Hall States Stabilized in Semi-magnetic Bilayers of Topological\n  Insulators: By breaking the time-reversal-symmetry in three-dimensional topological\ninsulators with introduction of spontaneous magnetization or application of\nmagnetic field, the surface states become gapped, leading to quantum anomalous\nHall effect or quantum Hall effect, when the chemical potential locates inside\nthe gap. Further breaking of inversion symmetry is possible by employing\nmagnetic topological insulator heterostructures that host nondegenerate top and\nbottom surface states. Here, we demonstrate the tailored-material approach for\nthe realization of robust quantum Hall states in the bilayer system, in which\nthe cooperative or cancelling combination of the anomalous and ordinary Hall\nresponses from the respective magnetic and non-magnetic layers is exemplified.\nThe appearance of quantum Hall states at filling factor 0 and +1 can be\nunderstood by the relationship of energy band diagrams for the two independent\nsurface states. The designable heterostructures of magnetic topological\ninsulator may explore a new arena for intriguing topological transport and\nfunctionality."
    },
    {
        "anchor": "Kibble-Zurek mechanism in driven-dissipative systems crossing a\n  non-equilibrium phase transition: The Kibble-Zurek mechanism constitutes one of the most fascinating and\nuniversal phenomena in the physics of critical systems. It describes the\nformation of domains and the spontaneous nucleation of topological defects when\na system is driven across a phase transition exhibiting spontaneous symmetry\nbreaking. While a characteristic dependence of the defect density on the speed\nat which the transition is crossed was observed in a vast range of equilibrium\ncondensed matter systems, its extension to intrinsically driven-dissipative\nsystems is a matter of ongoing research. In this work we numerically confirm\nthe Kibble-Zurek mechanism in a paradigmatic family of driven-dissipative\nquantum systems, namely exciton-polaritons in microcavities. Our findings show\nhow the concepts of universality and critical dynamics extend to\ndriven-dissipative systems that do not conserve energy or particle number nor\nsatisfy a detailed balance condition.",
        "positive": "A uniformly moving polarizable particle in a thermal radiation field\n  with arbitrary spin direction: We have generalized our recent results (Arm. J. Phys., 2014) relating to the\ndynamics, heating and radiation of a small rotating polarizable particle moving\nin a thermal radiation field in the case of arbitrary spin orientation. General\nexpressions for the tangential force, heating rate and intensity of thermal and\nnonthermal radiation are given. It is shown that the intensity of nonthermal\nradiation does not depend on the linear velocity and spin direction of the\nparticle."
    },
    {
        "anchor": "Electrooptics of graphene: field-modulated reflection and birefringence: The elecrooptical response of graphene due to heating and drift of carriers\nis studied theoretically. Real and imaginary parts of the dynamic conductivity\ntensor are calculated for the case of effective momentum relaxation, when\nanisotropic contributions are small. We use the quasiequilibrium distribution\nof electrons and holes, characterized by the effective temperature of carriers\nand by concentrations, which are controlled by gate voltage and in-plane\nelectric field. The geometry of normal propagation of probe radiation is\nconsidered, spectral and field dependences of the reflection coefficient and\nthe relative absorption are analyzed. The ellipticity degree of the reflected\nand transmitted radiation due to small birefringence of graphene sheet with\ncurrent have also been determined.",
        "positive": "Polarization entanglement visibility of photon pairs emitted by a\n  quantum dot embedded in a microcavity: We study the photon emission from a quantum dot embedded in a microcavity.\nIncoherent pumping of its excitons and biexciton provokes the emission of leaky\nand cavity modes. By solving a master equation we obtain the correlation\nfunctions required to compute the spectrum and the relative efficiency among\nthe emission of pairs and single photons. A quantum regime appears for low\npumping and large rate of emission. By means of a post-selection process, a two\nbeams experiment with different linear polarizations could be performed\nproducing a large polarization entanglement visibility precisely in the quantum\nregime."
    },
    {
        "anchor": "Minimum Anisotropy of a Magnetic Nanoparticle out of Equilibrium: In this article we study magnetotransport in single nanoparticles of Ni,\nPy=Ni$_{0.8}$Fe$_{0.2}$, Co, and Fe, with volumes $15\\pm 6$nm$^3$, using\nsequential electron tunneling at 4.2K temperature. We measure current versus\nmagnetic field in the ensembles of nominally the same samples, and obtain the\nabundances of magnetic hysteresis. The hysteresis abundance varies among the\nmetals as Ni:Py:Co:Fe=4\\,:50\\,:100\\,:100(\\%), in good correlation with the\nmagnetostatic and magnetocrystalline anisotropy. The abrupt change in the\nhysteresis abundance among these metals suggests a concept of minimum magnetic\nanisotropy required for magnetic hysteresis, which is found to be $\\approx\n13$meV. The minimum anisotropy is explained in terms of the residual\nmagnetization noise arising from the spin-orbit torques generated by sequential\nelectron tunneling. The magnetic hysteresis abundances are weakly dependent on\nthe tunneling current through the nanoparticle, which we attribute to current\ndependent damping.",
        "positive": "Emergent gravity and chiral anomaly in Dirac semimetals in the presence\n  of dislocations: We consider the recently discovered Dirac semimetals with two Dirac points\n$\\pm{\\bf K}$. In the presence of elastic deformations each fermion propagates\nin a curved space, whose metric is defined by the expansion of the effective\nHamiltonian near the Dirac point. Besides, there is the emergent\nelectromagnetic field that is defined by the shift of the Dirac point. We\nconsider the case, when the deformations are caused by the dislocations. The\ndislocation carries singular torsion and the quantized flux of emergent\nmagnetic field. Both torsion singularity and emergent magnetic flux may be\nobserved in the scattering of quasiparticles on the dislocation due to\nStodolsky and Aharonov - Bohm effects. We discuss quantum anomalies in the\nquasiparticle currents in the presence of emergent gauge and gravitational\nfields and the external electromagnetic field. In particular, it is\ndemonstrated, that in the presence of external electric field the\nquasiparticles/holes are pumped from vacuum along the dislocation. The appeared\nchiral imbalance along the dislocation drives the analogue of chiral magnetic\neffect, that is the appearance of electric current along the dislocation."
    },
    {
        "anchor": "Micropillars with a controlled number of site-controlled quantum dots: We report on the realization of micropillars with site-controlled quantum\ndots (SCQDs) in the active layer. The SCQDs are grown via the buried stressor\napproach which allows for the positioned growth and device integration of a\ncontrollable number of QDs with high optical quality. This concept is very\npowerful as the number and the position of SCQDs in the cavity can be\nsimultaneously controlled by the design of the buried stressor. The fabricated\nmicropillars exhibit a high degree of position control for the QDs above the\nburied stressor and $Q$-factors of up to 12000 at an emission wavelength around\n930 nm. We experimentally analyze and numerically model the cavity $Q$-factor,\nthe mode volume, the Purcell factor and the photon-extraction efficiency as a\nfunction of the aperture diameter of the buried stressor. Exploiting these SCQD\nmicropillars, we experimentally observe the Purcell enhancement in the\nsingle-QD regime with $F_P$ = 4.3 $\\pm$ 0.3.",
        "positive": "Robust temporal pumping in a magneto-mechanical topological insulator: The transport of energy through 1-dimensional (1D) waveguiding channels can\nbe affected by sub-wavelength disorder, resulting in undesirable localization\nand backscattering phenomena. However, quantized disorder-resilient transport\nis observable in the edge currents of 2-dimensional (2D) topological band\ninsulators with broken time-reversal symmetry. Topological pumps are able to\nreduce this higher-dimensional topological insulator phenomena to lower\ndimensionality by utilizing a pumping parameter (either space or time) as an\nartificial dimension. Here we demonstrate the first temporal topological pump\nthat produces on-demand, robust transport of mechanical energy using a 1D\nmagneto-mechanical metamaterial. We experimentally demonstrate that the system\nis uniquely resilient to defects occurring in both space and time Our findings\nopen a new path towards exploration of higher-dimensional topological physics\nwith time as a synthetic dimension."
    },
    {
        "anchor": "Dynamically stable negative-energy states induced by spin-transfer\n  torques: We investigate instabilities of the magnetic ground state in ferromagnetic\nmetals that are induced by uniform electrical currents, and, in particular, go\nbeyond previous analyses by including dipolar interactions. These instabilities\narise from spin-transfer torques that lead to Doppler shifted spin waves. For\nsufficiently large electrical currents, spin-wave excitations have negative\nenergy with respect to the uniform magnetic ground state, while remaining\ndynamically stable due to dissipative spin-transfer torques. Hence, the uniform\nmagnetic ground state is energetically unstable, but is not able to dynamically\nreach the new ground state. We estimate this to happen for current densities $\nj\\gtrsim (1-D/D_c)10^{13} \\mathrm{A/m^2} $ in typical thin film experiments,\nwith $ D $ the Dzyaloshinskii-Moriya interaction constant, and $ D_c $ the\nDzyaloshinskii-Moriya interaction that is required for spontaneous formation of\nspirals or skyrmions. These current densities can be made arbitrarily small for\nultrathin film thicknesses at the order of nanometers, due to surface- and\ninterlayer effects. From an analogue gravity perspective, the stable negative\nenergy states are an essential ingredient to implement event horizons for\nmagnons -- the quanta of spin waves -- giving rise to e.g. Hawking radiation\nand can be used to significantly amplify spin waves in a so-called black-hole\nlaser.",
        "positive": "Electrical manipulation of a ferromagnet by an antiferromagnet: We demonstrate that an antiferromagnet can be employed for a highly efficient\nelectrical manipulation of a ferromagnet. In our study we use an electrical\ndetection technique of the ferromagnetic resonance driven by an in-plane\nac-current in a NiFe/IrMn bilayer. At room temperature, we observe\nantidamping-like spin torque acting on the NiFe ferromagnet, generated by the\nin-plane current driven through the IrMn antiferromagnet. A large enhancement\nof the torque, characterized by an effective spin-Hall angle exceeding most\nheavy transition metals, correlates with the presence of the exchange-bias\nfield at the NiFe/IrMn interface. It highlights that, in addition to strong\nspin-orbit coupling, the antiferromagnetic order in IrMn governs the observed\nphenomenon."
    },
    {
        "anchor": "Disorder and interaction induced pairing in the addition spectra of\n  quantum dots: We have investigated numerically the electron addition spectra in quantum\ndots containing a small number (N < 11) of interacting electrons, in presence\nof strong disorder. For a short-range Coulomb repulsion, we find regimes in\nwhich two successive electrons enter the dot at very close values of the\nchemical potential. In the strongly correlated regime these close additions, or\npairing, are associated with electrons tunneling into distinct electron puddles\nwithin the dot. We discuss the tunneling rates at pairing, and we argue that\nour results are related to a phenomenon known as \"bunching\", recently observed\nexperimentally.",
        "positive": "Towards the fractional quantum Hall effect: a noncommutative geometry\n  perspective: In this paper we give a survey of some models of the integer and fractional\nquantum Hall effect based on noncommutative geometry. We begin by recalling\nsome classical geometry of electrons in solids and the passage to\nnoncommutative geometry produced by the presence of a magnetic field. We recall\nhow one can obtain this way a single electron model of the integer quantum Hall\neffect. While in the case of the integer quantum Hall effect the underlying\ngeometry is Euclidean, we then discuss a model of the fractional quantum Hall\neffect, which is based on hyperbolic geometry simulating the multi-electron\ninteractions. We derive the fractional values of the Hall conductance as\ninteger multiples of orbifold Euler characteristics. We compare the results\nwith experimental data."
    },
    {
        "anchor": "Landau level diagram and the continuous rotational symmetry breaking in\n  trilayer graphene: The sequence of the zeroth Landau levels (LLs) between filling factors\n$\\nu$=-6 to 6 in ABA-stacked trilayer graphene (TLG) is unknown because it\ndepends sensitively on the non-uniform charge distribution on the three layers\nof ABA-stacked TLG. Using the sensitivity of quantum Hall data on the electric\nfield and magnetic field, in an ultraclean ABA-stacked TLG sample, we\nquantitatively estimate the non-uniformity of the electric field and determine\nthe sequence of the zeroth LLs. We also observe anticrossings between some LLs\ndiffering by 3 in LL index, which result from the breaking of the continuous\nrotational to \\textit{C}$_3$ symmetry by the trigonal warping.",
        "positive": "Helicity-Changing Brillouin Light Scattering by Magnons in a\n  Ferromagnetic Crystal: Brillouin light scattering in ferromagnetic materials usually involves one\nmagnon and two photons and their total angular momentum is conserved. Here, we\nexperimentally demonstrate the presence of a helicity-changing two-magnon\nBrillouin light scattering in a ferromagetic crystal, which can be viewed as a\nfour-wave mixing process involving two magnons and two photons. Moreover, we\nobserve an unconventional helicity-changing one-magnon Brillouin light\nscattering, which apparently infringes the conservation law of the angular\nmomentum. We show that the crystal angular momentum intervenes to compensate\nthe missing angular momentum in the latter scattering process."
    },
    {
        "anchor": "Derivation of a time dependent Schr\u00f6dinger equation as quantum\n  mechanical Landau-Lifshitz-Bloch equation: The derivation of the time dependent Schr\\\"odinger equation with transversal\nand longitudinal relaxation, as the quantum mechanical analog of the classical\nLandau-Lifshitz-Bloch equation, has been described. Starting from the classical\nLandau-Lifshitz-Bloch equation the transition to quantum mechanics has been\nperformed and the corresponding von-Neumann equation deduced. In a second step\nthe time Schr\\\"odinger equation has been derived. Analytical proofs and\ncomputer simulations show the correctness and applicability of the derived\nSchr\\\"odinger equation.",
        "positive": "Universal control and error correction in multi-qubit spin registers in\n  diamond: Quantum registers of nuclear spins coupled to electron spins of individual\nsolid-state defects are a promising platform for quantum information\nprocessing. Pioneering experiments selected defects with favourably located\nnuclear spins having particularly strong hyperfine couplings. For progress\ntowards large-scale applications, larger and deterministically available\nnuclear registers are highly desirable. Here we realize universal control over\nmulti-qubit spin registers by harnessing abundant weakly coupled nuclear spins.\nWe use the electron spin of a nitrogen-vacancy centre in diamond to selectively\ninitialize, control and read out carbon-13 spins in the surrounding spin bath\nand construct high-fidelity single- and two-qubit gates. We exploit these new\ncapabilities to implement a three-qubit quantum-error-correction protocol and\ndemonstrate the robustness of the encoded state against applied errors. These\nresults transform weakly coupled nuclear spins from a source of decoherence\ninto a reliable resource, paving the way towards extended quantum networks and\nsurface-code quantum computing based on multi-qubit nodes."
    },
    {
        "anchor": "Spin states of the first four holes in a silicon nanowire quantum dot: We report measurements on a silicon nanowire quantum dot with a clarity that\nallows for a complete understanding of the spin states of the first four holes.\nFirst, we show control of the hole number down to one. Detailed measurements at\nperpendicular magnetic fields reveal the Zeeman splitting of a single hole in\nsilicon. We are able to determine the ground-state spin configuration for one\nto four holes occupying the quantum dot and find a spin filling with\nalternating spin-down and spin-up holes, which is confirmed by\nmagnetospectroscopy up to 9T. Additionally, a so far inexplicable feature in\nsingle-charge quantum dots in many materials systems is analyzed in detail. We\nobserve excitations of the zero-hole ground-state energy of the quantum dot,\nwhich cannot correspond to electronic or Zeeman states. We show that the most\nlikely explanation is acoustic phonon emission to a cavity between the two\ncontacts to the nanowire.",
        "positive": "Anomalous Transport Signatures in Weyl Semimetals with Point Defects: We present the first theoretical study of transport properties of Weyl\nsemimetals with point defects. Focusing on a class of time-reversal symmetric\nWeyl lattice models, we show that dilute lattice vacancies induce a finite\ndensity of quasi-localized states at and near the nodal energy, causing strong\nmodifications to the low-energy spectrum. This generates novel transport\neffects, namely (i) an oscillatory behaviour of the dc-conductivity with the\ncharge carrier density in the absence of magnetic fields, and (ii) a\nplateau-shaped dissipative optical response for photon frequencies below the\ninter-band threshold, $E_{F}\\!\\lesssim\\!\\hbar\\omega\\!\\lesssim\\!2E_{F}$.Our\nresults provide a path to engineer unconventional quantum transport effects in\nWeyl semimetals by means of common point defects."
    },
    {
        "anchor": "Observation of Pure Spin Transport in a Diamond Spin Wire: Spin transport electronics - spintronics - focuses on utilizing electron spin\nas a state variable for quantum and classical information processing and\nstorage. Some insulating materials, such as diamond, offer defect centers whose\nassociated spins are well-isolated from their environment giving them long\ncoherence times; however, spin interactions are important for transport,\nentanglement, and read-out. Here, we report direct measurement of pure spin\ntransport - free of any charge motion - within a nanoscale quasi 1D 'spin\nwire', and find a spin diffusion length ~ 700 nm. We exploit the statistical\nfluctuations of a small number of spins ($\\sqrt{N}$ < 100 net spins) which are\nin thermal equilibrium and have no imposed polarization gradient. The spin\ntransport proceeds by means of magnetic dipole interactions that induce\nflip-flop transitions, a mechanism that can enable highly efficient, even\nreversible, pure spin currents. To further study the dynamics within the spin\nwire, we implement a magnetic resonance protocol that improves spatial\nresolution and provides nanoscale spectroscopic information which confirms the\nobserved spin transport. This spectroscopic tool opens a potential route for\nspatially encoding spin information in long-lived nuclear spin states. Our\nmeasurements probe intrinsic spin dynamics at the nanometre scale, providing\ndetailed insight needed for practical devices which seek to control spin.",
        "positive": "Topological nature of nonlinear optical effects in solids: There are a variety of nonlinear optical effects including higher harmonic\ngenerations, photovoltaic effects, and nonlinear Kerr rotations. They are\nrealized by the strong light irradiation to materials that results in nonlinear\npolarizations in the electric field. These are of great importance in studying\nthe physics of excited states of the system as well as for applications to\noptical devices and solar cells. Nonlinear properties of materials are usually\ndescribed by the nonlinear susceptibilities $\\chi$'s, which have complex\nexpressions including many matrix elements and energy denominators. On the\nother hand, a nonequilibrium steady state under a electric field periodic in\ntime has a concise description in terms of the Floquet bands of electrons\ndressed by photons. Here, we theoretically show by using the Floquet formalism\nthat various nonlinear optical effects, such as the shift current in\nnoncentrosymmetric materials, photovoltaic Hall response, and photo-induced\nchange of order parameters under the continuous irradiation of monochromatic\nlight, can be described in a unified fashion by topological quantities\ninvolving the Berry connection and Berry curvature. It is found that vector\nfields defined with the Berry connections in the space of momentum and/or\nparameters govern the nonlinear responses. This topological view offers a new\nroute to design the nonlinear optical materials."
    },
    {
        "anchor": "Theory of three-magnon interaction in a vortex-state magnetic nanodot: We use vector Hamiltonian formalism (VHF) to study theoretically three-magnon\nparametric interaction (or three-wave splitting) in a magnetic disk existing in\na magnetic vortex ground state. The three-wave splitting in a disk is found to\nobey two selection rules: (i) conservation of the total azimuthal number of the\nresultant spin-wave modes, and (ii) inequality for the radial numbers of\ninteracting modes, if the mode directly excited by the driving field is\nradially symmetric (i.e. if the azimuthal number of the directly excited mode\nis $m = 0$). The selection rule (ii), however, is relaxed in the \"small\"\nmagnetic disks, due to the influence of the vortex core. We also found, that\nthe efficiency of the three-wave interaction of the directly excited mode\nstrongly depends on the azimuthal and radial mode numbers of the resultant\nmodes, that becomes determinative in the case when several splitting channels\n(several pairs of resultant modes) simultaneously approximately satisfy the\nresonance condition for the splitting. The good agreement of the VHF analytic\ncalculations with the experiment and micromagnetic simulations proves the\ncapability of the VHF formalism to predict the actual splitting channels and\nthe magnitudes of the driving field thresholds for the three-wave splitting.",
        "positive": "Magnetotransport in a time-modulated double quantum point contact system: We report on a time-dependent Lippmann-Schwinger scattering theory that\nallows us to study the transport spectroscopy in a time-modulated double\nquantum point contact system in the presence of a perpendicular magnetic field.\nMagnetotransport properties involving inter-subband and inter-sideband\ntransitions are tunable by adjusting the time-modulated split-gates and the\napplied magnetic field. The observed magnetic field induced Fano resonance\nfeature may be useful for the application of quantum switching."
    },
    {
        "anchor": "Quantum Hydrodynamics of Vorticity: We formulate a quantum theory of vorticity (hydro)dynamics on a general\ntwo-dimensional bosonic lattice. In the classical limit of a bosonic\ncondensate, it reduces to conserved plasma-like vortex-antivortex dynamics. The\nnonlocal topological character of the vorticity flows is reflected in the\nbulk-edge correspondence dictated by the Stokes theorem. This is exploited to\nestablish physical boundary conditions that realize, in the coarse-grained\nthermodynamic limit, an effective chemical-potential bias of vorticity. A Kubo\nformula is derived for the vorticity conductivity|which could be measured in a\nsuggested practical device|in terms of quantum vorticity-flux correlators of\nthe original lattice model. As an illustrative example, we discuss the\nsuperfluidity of vorticity, exploiting the particle-vortex duality at a bosonic\nsuperfluid-insulator transition.",
        "positive": "Proposal for a dual spin filter based on [VO(C$_3$S$_4$O)$_2$]$^{2-}$: Polynuclear magnetic molecules often present dense transmission spectra with\nmany overlapping conduction spin channels. Single-metal complexes display a\nsparser density of states, which in the presence of a fixed external magnetic\nfield makes them interesting candidates for spin filtering. Here we perform a\nDFT study of a family of bis- and tris-dithiolate vanadium complexes sandwiched\nbetween Au(111) electrodes and demonstrate that [VO(C$_3$S$_4$O)$_2$]$^{2-}$\ncan behave as a dual spin filter. This means that an external stimulus can\nswitch between the selective transmission of spin-up and spin-down carriers. By\nusing an electrostatic gate as external stimulus we show that the onset for the\nspin-up conductance is at a voltage V$_g$ = -0.51 V but a small shift to V$_g$\n= -0.63 V is capable of activating spin-down transport. For both cases, we\nestimate a large low-bias conductance (approx. 2 {\\mu}S at Vbias < 50 mV) with\nexcellent spin selectivity (> 99.5%). We conclude by commenting on the general\nmolecular requirements for the chemical design of further such spintronics\ncomponents."
    },
    {
        "anchor": "Luminescent emission of excited Rydberg excitons from monolayer WSe2: We report the experimental observation of radiative recombination from\nRydberg excitons in a two-dimensional semiconductor, monolayer WSe2,\nencapsulated in hexagonal boron nitride. Excitonic emission up to the 4s\nexcited state is directly observed in photoluminescence spectroscopy in an\nout-of-plane magnetic field up to 31 Tesla. We confirm the progressively larger\nexciton size for higher energy excited states through diamagnetic shift\nmeasurements. This also enables us to estimate the 1s exciton binding energy to\nbe about 170 meV, which is significantly smaller than most previous reports.\nThe Zeeman shift of the 1s to 3s states, from both luminescence and absorption\nmeasurements, exhibits a monotonic increase of g-factor, reflecting nontrivial\nmagnetic-dipole-moment differences between ground and excited exciton states.\nThis systematic evolution of magnetic dipole moments is theoretically explained\nfrom the spreading of the Rydberg states in momentum space.",
        "positive": "The gate tunable 2D pn junction driven out-of-equilibrium: We have investigated the electrostatics and electronic transport of the gate\ntunable 2D pn junction by implementing a comprehensive physics-based simulator\nthat self-consistently solves the 2D Poisson's equation coupled to the\ndrift-diffusion current and continuity equations. The simulator considers the\nstrong influence of the out-of-plane electric field through the gate dielectric\nand the presence of interface states. The impact of parameters such as gate\ncapacitance, energy gap and interface trap states density have been considered\nto model properties such as the depletion width, rectification factor and\ndepletion and diffusion capacitances. The present work opens the door to a\nwider exploration of potential advantages that gate tunable 2D pn junctions\ncould bring in terms of figures of merit."
    },
    {
        "anchor": "Perturbation theory of a superconducting $0-\u03c0$ impurity quantum phase\n  transition: A single-level quantum dot with Coulomb repulsion attached to two\nsuperconducting leads is studied via the perturbation expansion in the\ninteraction strength. We use the Nambu formalism and the standard many-body\ndiagrammatic representation of the impurity Green functions to formulate the\nMatsubara self-consistent perturbation expansion. We show that at zero\ntemperature second order of the expansion in its $\\it{spin-symmetric}$ version\nyields a nearly perfect agreement with the numerically exact calculations for\nthe position of the $0-\\pi$ phase boundary at which the Andreev bound states\nreach the Fermi energy as well as for the values of single-particle quantities\nin the 0-phase. We present results for phase diagrams, level occupation,\ninduced local superconducting gap, Josephson current, and energy of the Andreev\nbound states with the precision surpassing any (semi)analytical approaches\nemployed thus far.",
        "positive": "Nonreciprocal transmission of neutrons through the noncoplanar magnetic\n  system: We report on observation of the time reversal symmetry breaking in\nunpolarized neutrons scattering experiment. Neutron transmittivity through the\nsystem consisting of two magnetic mirrors placed in an external magnetic field\nis measured. Time reversal symmetry holds for coplanar magnetic configuration,\nmeaning that transmitted intensity does not change when interchanging neutron\nsource and detector. Contrarily, for noncoplanar magnetic configuration the\ntime reversal symmetry breaks down. In this case the transmitted intensity\nchanges when interchanging the source and detector. The observed time reversal\nsymmetry breaking is the consequence of the one of the most fundamental\nproperties of quantum mechanics, namely the non-commutativity of spin algebra."
    },
    {
        "anchor": "Time-Reversal Symmetry Breaking and Decoherence in Chaotic Dirac\n  Billiards: In this work, we perform a statistical study on Dirac Billiards in the\nextreme quantum limit (a single open channel on the leads). Our numerical\nanalysis uses a large ensemble of random matrices and demonstrates the\npreponderant role of dephasing mechanisms in such chaotic billiards. Physical\nimplementations of these billiards range from quantum dots of graphene to\ntopological insulators structures. We show, in particular, that the role of\nfinite crossover fields between the universal symmetries quickly leaves the\nconductance to the asymptotic limit of unitary ensembles. Furthermore, we show\nthat the dephasing mechanisms strikingly lead Dirac billiards from the extreme\nquantum regime to the semiclassical Gaussian regime.",
        "positive": "Thermally induced antiferromagnetic exchange in magnetic multilayers: We demonstrate sharp thermally-induced switching between ferromagnetic and\nantiferromagnetic RKKY exchange in a spin-valve with the spacer incorporating a\nthin diluted ferromagnetic layer as the core. We illustrate the mechanism\nbehind the effect as due to a change in the effective thickness of the spacer\ninduced by the Curie transition into its paramagnetic state."
    },
    {
        "anchor": "Coherent monochromatic phonons in highly-purified semiconducting\n  single-wall carbon nanotubes: We have used a femtosecond pump-probe impulsive Raman technique to explore\nthe polarization dependence of coherent optical phonons in highly-purified and\naligned semiconducting single-wall carbon nanotubes (SWCNTs). Coherent phonon\nspectra for the radial breathing modes (RBMs) exhibit a different monochromatic\nfrequency between the film and solution samples, indicating the presence of\ndiffering exciton excitation processes. By varying the polarization of the\nincident pump beam on the aligned SWCNT film, we found that the anisotropy of\nthe coherent RBM excitation depends on the laser wavelength, which we consider\nto be associated with the resonant and off-resonant behavior of RBM excitation.",
        "positive": "Semimetallic carbon allotrope with topological nodal line in mixed\n  $sp^2$-$sp^3$ bonding networks: Graphene is known as a two-dimensional Dirac semimetal, in which electron\nstates are described by the Dirac equation of relativistic quantum mechanics.\nThree-dimensional analogues of graphene are characterized by Dirac points or\nlines in momentum space, which are protected by symmetry. Here, we report a\nnovel 3D carbon allotrope belonging to a class of topological nodal line\nsemimetals, discovered by using an evolutionary structure search method. The\nnew carbon phase in monoclinic $C$2$/m$ space group, termed $m$-$C_8$, consists\nof five-membered rings with $sp^3$ bonding interconnected by $sp^2$-bonded\ncarbon networks. Enthalpy calculations reveal that $m$-$C_8$ is more favorable\nover recently reported topological semimetallic carbon allotropes, and the\ndynamical stability of $m$-$C_8$ is verified by phonon spectra and molecular\ndynamics simulations. Simulated x-ray diffraction spectra propose that\n$m$-$C_8$ would be one of the unidentified carbon phases observed in detonation\nshoot. The analysis of electronic properties indicates that $m$-$C_8$ exhibits\nthe nodal line protected by both inversion and time-reversal symmetries in the\nabsence of spin-orbit coupling and the surface band connecting the projected\nnodal points. Our results may help design new carbon allotropes with exotic\nelectronic properties."
    },
    {
        "anchor": "Detecting Majorana nonlocality using strongly coupled Majorana bound\n  states: Majorana bound states (MBS) differ from the regular zero energy Andreev bound\nstates in their nonlocal properties, since two MBS form a single fermion. We\ndesign strategies for detection of this nonlocality by using the phenomenon of\nCoulomb-mediated Majorana coupling in a simplest setting which still retains\nfalsifiability. Focusing on the implementation of MBS based on the quantum spin\nHall effect, we also design a way to probe Majoranas without the need to open a\nmagnetic gap in the helical edge states. In the setup that we analyse, long\nrange MBS coupling manifests in the $h/e$ magnetic flux periodicity of\ntunneling conductance and supercurrent. While $h/e$ is also the periodicity of\nAharonov-Bohm effect and persistent current, we show how to ensure its Majorana\norigin by verifying that switching off the charging energy restores $h/2e$\nperiodicity conventional for superconducting systems.",
        "positive": "Towards Universal Non-Volatile Resistance Switching in Non-metallic\n  Monolayer Atomic Sheets: Here, we report the intriguing observation of stable non-volatile resistance\nswitching (NVRS) in single-layer atomic sheets sandwiched between metal\nelectrodes. NVRS is observed in the prototypical semiconducting (MX2, M=Mo, W;\nand X=S, Se) transitional metal dichalcogenides (TMDs), and insulating\nhexagonal boron nitride (h-BN), which alludes to the universality of this\nphenomenon in non-metallic 2D monolayers, and features forming-free switching.\nThis observation of NVRS phenomenon, widely attributed to ionic diffusion,\nfilament and interfacial redox in bulk oxides and electrolytes, inspires new\nstudies on defects, ion transport and energetics at the sharp interfaces\nbetween atomically-thin sheets and conducting electrodes. From a contemporary\nperspective, switching is all the more unexpected in monolayers since leakage\ncurrent is a fundamental limit in ultra-thin oxides. Emerging device concepts\nin non-volatile flexible memory fabrics, and brain-inspired (neuromorphic)\ncomputing could benefit substantially from the pervasive NVRS effect and the\nassociated wide materials and engineering co-design opportunity.\nExperimentally, a 50 GHz radio-frequency (RF) monolayer switch is demonstrated,\nwhich opens up a new application for electronic zero-static power RF switching\ntechnology."
    },
    {
        "anchor": "Orientational pinning of quantum Hall striped phase: In ultra-clean 2D electron systems on (001) GaAs/AlGaAs upon filling high\nLandau levels, it was recently observed a new class of collective states, which\ncan be related to the spontaneous formation of a charge density wave (``striped\nphase''). We address to the following unsolved problem: what is the reason for\nstripe pinning along the crystallographic direction [110]? It is shown that in\na single heterojunction (001) III-V the effective mass of 2D electrons is\nanisotropic. This natural anisotropy is due to the reduced (C_{2v}) symmetry of\nthe heterojunction and, even being weak (0.1 percent), can govern the stripe\ndirection. A magnetic field parallel to the interface induces ``magnetic''\nanisotropy of the effective mass. The competition of these two types of\nanisotropy provides quantitative description of the experiment.",
        "positive": "Colloquium: Quantum skyrmionics: Skyrmions are topological solitons that emerge in many physical contexts. In\nmagnetism, they appear as textures of the spin-density field stabilized by\ndifferent competing interactions and characterized by a topological charge that\ncounts the number of times the order parameter wraps the sphere. They can\nbehave as classical objects, when the spin texture varies slowly on the scale\nof the microscopic lattice of the magnet. However, the fast development of\nexperimental tools to create and stabilize skyrmions in thin magnetic films has\nlead to a rich variety of textures, sometimes of atomistic sizes. In this\narticle, we discuss, in a pedagogical manner, how to introduce quantum\ninterference in the translational dynamics of skyrmion textures, starting from\nthe micromagnetic equations of motion for a classical soliton. We study how the\nnontrivial topology of the spin texture manifests in the semiclassical regime,\nwhen the microscopic lattice potential is treated quantum-mechanically, but the\nexternal driving forces are taken as smooth classical perturbations. We\nhighlight close relations to the fields of noncommutative quantum mechanics,\nChern-Simons theories, and the quantum Hall effect."
    },
    {
        "anchor": "Radio-frequency reflectometry in bilayer graphene devices utilizing\n  micro graphite back-gates: Bilayer graphene is an attractive material that realizes high-quality\ntwo-dimensional electron gas with a controllable bandgap. By utilizing the\nbandgap, electrical gate tuning of the carrier is possible and formation of\nnanostructures such as quantum dots have been reported. To probe the dynamics\nof the electronics states and realize applications for quantum bit devices,\nRF-reflectometry which enables high-speed electric measurements is important.\nHere we demonstrate RF-reflectometry in bilayer graphene devices. We utilize a\nmicro graphite back-gate and an undoped Si substrate to reduce the parasitic\ncapacitance which degrades the RF-reflectometry. We measure the resonance\nproperties of a tank circuit which contains the bilayer graphene device. We\nform RF-reflectmetory setup and compared the result with the DC measurement,\nand confirmed their consistency. We also measure Coulomb diamonds of quantum\ndots possibly formed by bubbles and confirm that RF-reflectometry of quantum\ndots can be performed. This technique enables high-speed measurements of\nbilayer graphene quantum dots and contributes to the research of bilayer\ngraphene-based quantum devices by fast readout of the states.",
        "positive": "Unconventional field-effect transistor composed of electrons floating on\n  liquid helium: We report on an unconventional $macroscopic$ field effect transistor composed\nof electrons floating above the surface of superfluid helium. With this device\nunique transport regimes are realized in which the charge density of the\nelectron layer can be controlled in a manner not possible in other material\nsystems. In particular, we are able to manipulate the collective behavior of\nthe electrons to produce a highly non-uniform, but precisely controlled, charge\ndensity to reveal a negative source-drain current. This behavior can be\nunderstood by considering the propagation of damped charge oscillations along a\ntransmission line formed by the inhomogeneous sheet of two-dimensional\nelectrons above, and between, the source and drain electrodes of the\ntransistor."
    },
    {
        "anchor": "Analytical theory and possible detection of the $ac$ quantum spin Hall\n  effect: We develop an analytical theory of the low-frequency $ac$ quantum spin Hall\n(QSH) effect based upon the scattering matrix formalism. It is shown that the\n$ac$ QSH effect can be interpreted as a bulk quantum pumping effect. When the\nelectron spin is conserved, the integer-quantized $ac$ spin Hall conductivity\ncan be linked to the winding numbers of the reflection matrices in the\nelectrodes, which also equal to the bulk spin Chern numbers of the QSH\nmaterial. Furthermore, a possible experimental scheme by using ferromagnetic\nmetals as electrodes is proposed to detect the topological $ac$ spin current by\nelectrical means.",
        "positive": "Effect of magnetic field on intersubband polaritons in a quantum well:\n  Strong to weak coupling conversion: We investigate theoretically the effect of a magnetic field on intersubband\npolaritons in an asymmetric quantum well placed inside an optical resonator. It\nis demonstrated that the field-induced diamagnetic shift of electron subbands\nin the well increases the broadening of optical lines corresponding to\nintersubband electron transitions. As a consequence, the magnetic field can\nswitch the polariton system from the regime of strong light-matter coupling to\nthe regime of weak one. This effect paves a way to the effective control of\npolaritonic devices with a magnetic field."
    },
    {
        "anchor": "Dissolution of topological Fermi arcs in a dirty Weyl semimetal: Weyl semimetals (WSMs) have recently attracted a great deal of attention as\nthey provide condensed matter realization of chiral anomaly, feature\ntopologically protected Fermi arc surface states and sustain sharp chiral Weyl\nquasiparticles up to a critical disorder at which a continuous quantum phase\ntransition (QPT) drives the system into a metallic phase. We here numerically\ndemonstrate that with increasing strength of disorder the Fermi arc gradually\nlooses its sharpness, and close to the WSM-metal QPT it completely dissolves\ninto the metallic bath of the bulk. Predicted topological nature of the\nWSM-metal QPT and the resulting bulk-boundary correspondence across this\ntransition can directly be observed in\nangle-resolved-photo-emmision-spectroscopy (ARPES) and Fourier transformed\nscanning-tunneling-microscopy (STM) measurements by following the continuous\ndeformation of the Fermi arcs with increasing disorder in recently discovered\nWeyl materials.",
        "positive": "Quantum interferences in quasicrystals: Contributions of quantum interference effects occuring in quasicrystals are\nemphasized. First conversely to metallic systems, quasiperiodic ones are shown\nto enclose original alterations of their conductive properties while\ndowngrading long range order. Besides, origins of localization mechanisms are\noutlined within the context of the original metal-insulator transition (MIT)\nfound in these materials."
    },
    {
        "anchor": "Resonance Patterns of an Antidot Cluster: From Classical to Quantum\n  Ballistics: We explain the experimentally observed Aharonov-Bohm (AB) resonance patterns\nof an antidot cluster by means of quantum and classical simulations and Feynman\npath integral theory. We demonstrate that the observed behavior of the AB\nperiod signals the crossover from a low B regime which can be understood in\nterms of electrons following classical orbits to an inherently quantum high B\nregime where this classical picture and semiclassical theories based on it do\nnot apply.",
        "positive": "Thermopower, figure of merit, quantum dot, Kondo effect, orbital degrees\n  of freedom: We study the thermopower and some related transport quantities due to the\norbital Kondo effect in a single quantum dot system with a finite value of\nCoulomb repulsion by means of the noncrossing approximation applied to the\nmultiorbital impurity Anderson model. It is elucidated how the asymmetry of the\nrenormalized tunneling resonance due to the two-orbital Kondo effect causes\ncharacteristic behavior of the thermopower at finite temperatures under\ngate-voltage and magnetic-field control, which is compared with that of the\nordinary spin Kondo effect."
    },
    {
        "anchor": "Exchange interaction-driven dynamic nuclear polarization in Mn-doped\n  InGaAs/GaAs quantum dots: We investigated optical spin orientation and dynamic nuclear polarization\n(DNP) in individual self-assembled InGaAs/GaAs quantum dots (QDs) doped by a\nsingle Mn atom, a magnetic impurity providing a neutral acceptor A$^0$ with an\neffective spin $J=1$. We find that the spin of an electron photo-created in\nsuch a quantum dot can be efficiently oriented by a quasi-resonant\ncircularly-polarized excitation. For the electron spin levels which are made\nquasi-degenerate by a magnetic field compensating the exchange interaction\n$\\Delta_e$ with A$^0$, there is however a full depolarization due the\nanisotropic part of the exchange. Still, in most studied QDs, the spin\npolarized photo-electrons give rise to a pronounced DNP which grows with a\nlongitudinal magnetic field until a critical field where it abruptly vanishes.\nFor some QDs, several replica of such DNP sequence are observed at different\nmagnetic fields. This striking behavior is qualitatively discussed as a\nconsequence of different exchange interactions experienced by the electron,\ndriving the DNP rate via the energy cost of electron-nucleus spin flip-flops.",
        "positive": "Electronic transport close to boundaries of semi-infinite graphene and\n  their interfaces: Transport properties of 2D materials especially close to their boundary has\nreceived much attention after the successful fabrication of graphene and other\nfascinating materials afterwards. While most previous work is devoted to the\nconventional lead-device-lead setup with a finite size center area, this\nproject investigates real space transport properties of infinite and\nsemi-infinite 2D system under the framework of Non-equilibrium Green function.\nThe commonly used method of calculating the Green function by inverting a\nmatrix in the real space directly can be unstable in dealing with large systems\nas sometimes it gives non-converging result. Not to mention that the\ncalculation error and time increase drastically with size of the system. By\ntransforming from the real space to momentum space, we managed to replace the\nmatrix inverting process by Brillouin Zone integral process which can be\ngreatly simplified by the application of contour integral. Combining this\nmethodology with Dyson equations, we are able to calculate transport properties\nof semi-infinite graphene close to its zigzag boundary and its combination with\nother material including s-wave superconductor. Interference pattern of\ntransmitted and reflected electrons, graphene lensing effects and difference\nbetween Specular Andreev reflection and normal Andreev reflection are verified\nthrough our calculation."
    },
    {
        "anchor": "Disorder-induced rippled phases and multicriticality in free-standing\n  graphene: One of the most exciting phenomena observed in crystalline disordered\nmembranes, including a suspended graphene, is rippling, i.e. a formation of\nstatic flexural deformations. Despite an active research, it still remains\nunclear whether the rippled phase exists in the thermodynamic limit, or it is\ndestroyed by thermal fluctuations. We demonstrate that a sufficiently strong\nshort-range disorder stabilizes ripples, whereas in the case of a weak disorder\nthe thermal flexural fluctuations dominate in the thermodynamic limit. The\nphase diagram of the disordered suspended graphene contains two separatrices:\nthe crumpling transition line dividing the flat and crumpled phases and the\nrippling transition line demarking the rippled and clean phases. At the\nintersection of the separatrices there is the unstable, multicritical point\nwhich splits up all four phases. Most remarkably, rippled and clean flat phases\nare described by a single stable fixed point which belongs to the rippling\ntransition line. Coexistence of two flat phases in the single point is possible\ndue to non-analiticity in corresponding renormalization group equations and\nreflects non-commutativity of limits of vanishing thermal and rippling\nfluctuations.",
        "positive": "Scattering of electromagnetic waves from a cone with conformal mapping:\n  application to scanning near-field optical microscope: We study the response of a conical metallic surface to an external\nelectromagnetic (EM) field by representing the fields in basis functions\ncontaining integrable singularities at the tip of the cone. A fast analytical\nsolution is obtained by the conformal mapping between the cone and a round\ndisk. We apply our calculation to the scattering- based scanning near-field\noptical microscope (s-SNOM) and successfully quantify the elastic light\nscattering from a vibrating metallic tip over a uniform sample. We find that\nthe field-induced charge distribution consists of localized terms at the tip\nand the base and an extended bulk term along the body of the cone far away from\nthe tip. In recent s-SNOM experiments at the visible-IR range (600nm - 1$\\mu\nm$) the fundamental is found to be much larger than the higher harmonics\nwhereas at THz range ($100 \\mu m-3mm$) the fundamental becomes comparable to\nthe higher harmonics. We find that the localized tip charge dominates the\ncontribution to the higher harmonics and becomes bigger for the THz\nexperiments, thus providing an intuitive understanding of the origin of the\nnear-field signals. We demonstrate the application of our method by extracting\na two-dimensional effective dielectric constant map from the s-SNOM image of a\nfinite metallic disk, where the variation comes from the charge density induced\nby the EM field."
    },
    {
        "anchor": "Towards femtosecond on-chip electronics: To combine the advantages of ultrafast femtosecond optics with an on-chip\ncommuncation scheme, optical signals with a frequency of several hundreds of\nTHz need to be down-converted to coherent electronic signals of GHz or less. So\nfar, this has not been achieved because of the impedance mismatch within\nelectronic circuits and their overall slow response-time. Here, we demonstrate\nthat 14 fs optical pulses in the near-infrared (NIR) can drive electronic\non-chip circuits with a bandwidth up to 10 THz. The corresponding electronic\npulses propagate in microscopic striplines on a millimeter scale. We exploit\nfemtosecond photoswitches based on tunneling barriers in nanoscale metal\njunctions to drive the pulses. The non-linear ultrafast response is based on a\ncombination of plasmonically enhanced, multi-photon absorption and quantum\ntunneling, and gives rise to a field emission of ballistic electrons\npropagating across the nanoscale junctions. Our results pave the way towards\nfemtosecond electronics integrated in waferscale quantum circuits.",
        "positive": "The Quantum Anomalous Hall Majorana Platform: We show that quasi-one-dimensional (1D) quantum wires can be written onto the\nsurface of magnetic topological insulator (MTI) thin films by gate arrays. When\nthe MTI is in a quantum anomalous Hall (QAH) state, MTI$/$superconductor\nquantum wires have especially broad stability regions for both topological and\nnon-topological states, facilitating creation and manipulation of Majorana\nparticles on the MTI surface."
    },
    {
        "anchor": "Fine tuning of phase qubit parameters for optimization of fast\n  single-pulse readout: We analyze a two-level quantum system, describing the phase qubit, during a\nsingle-pulse readout process by a numerical solution of the time-dependent\nSchroedinger equation. It has been demonstrated that the readout error has a\nminimum for certain values of the system`s basic parameters. In particular, the\noptimization of the qubit capacitance and the readout pulse shape leads to\nsignificant reduction of the readout error. It is shown that in an ideal case\nthe fidelity can be increased to almost 97% for 2 ns pulse duration and to 96%\nfor 1 ns pulse duration.",
        "positive": "Transport-based fusion that distinguishes between Majorana and Andreev\n  bound states: It has proven difficult to distinguish between topological Majorana bound\nstates and nontopological Andreev bound states and to measure the unique\nproperties of the former. In this work, we aim to alleviate this problem by\nproposing and theoretically analyzing a new type of fusion protocol based on\ntransport measurements in a Majorana box coupled to normal leads. The protocol\nis based on switching between different nanowire pairs being tunnel coupled to\none of the leads. For a Majorana system, this leads to switching between\ndifferent states associated with parity blockade. The charge being transmitted\nat each switch provides a measurement of the Majorana fusion rules.\nImportantly, the result is different for a system with nontopological Andreev\nbound states. The proposed protocol only requires measuring a DC current\ncombined with fast gate-control of the tunnel couplings."
    },
    {
        "anchor": "The Eikonal Approximation of the Scattering Theory for Fast Charged\n  Particles in a Thin Layer of Crystalline and Amorphous Media: On the basis of the eikonal approximation of quantum scattering theory, the\nproblem of fast charged particles scattering in a thin crystal when particles\nfall along one its plane of atoms and in a thin layer of amorphous matter is\nconsidered. It is shown that the scattering cross section in this problem, for\nparameters, which are beyond the scope of application of the Born perturbation\ntheory, differs significantly from the corresponding result of the Born\napproximation. In this case, the scattering in the transverse to the plane\ndirection is determined mainly by a continuous plane potential, which is widely\nused in the theory of the channeling phenomenon. The scattering of a particle\nin the longitudinal direction has features of scattering in a two-dimensional\namorphous medium with inhomogeneous density of atoms. The concept of a\ncontinuous potential of the crystal plane of atoms in the considered approach\nappears automatically.",
        "positive": "Nonlinear properties and stabilities of polaritonic crystals beyond the\n  low-excitation-density limit: Coherent properties of a two dimensional spatially periodic structure -\npolaritonic crystal (PolC) formed by trapped two-level atoms in an optical\ncavity array interacting with a light field, are analyzed. By considering the\nwave function overlapping both for photonic and atomic states, a cubic-quintic\ncomplex nonlinear Schrodinger equation (CNLSE) is derived for the dynamics of\ncoupled atom-light states - wave function of low branch (LB) polaritons,\nassociated with PolC in the continuous limit. The variational approach predicts\nthat a stable ground state wave function of PolC exists but is accompanied by\nan oscillating width. For a negative scattering length, the wave function\ncollapses in the presence of a small quintic nonlinearity appear due to a three\nbody polariton interaction. Studying non-equilibrium (dissipative) dynamics of\npolaritons with adiabatic approximation we have shown that the collapse of PolC\nwave function can be prevented even in the presence of small decaying of a\nnumber of polariton particles."
    },
    {
        "anchor": "Electron Transport through Disordered Domain Walls: Coherent and\n  Incoherent Regimes: We study electron transport through a domain wall in a ferromagnetic nanowire\nsubject to spin-dependent scattering. A scattering matrix formalism is\ndeveloped to address both coherent and incoherent transport properties. The\ncoherent case corresponds to elastic scattering by static defects, which is\ndominant at low temperatures, while the incoherent case provides a\nphenomenological description of the inelastic scattering present in real\nphysical systems at room temperature. It is found that disorder scattering\nincreases the amount of spin-mixing of transmitted electrons, reducing the\nadiabaticity. This leads, in the incoherent case, to a reduction of conductance\nthrough the domain wall as compared to a uniformly magnetized region which is\nsimilar to the giant magnetoresistance effect. In the coherent case, a\nreduction of weak localization, together with a suppression of spin-reversing\nscattering amplitudes, leads to an enhancement of conductance due to the domain\nwall in the regime of strong disorder. The total effect of a domain wall on the\nconductance of a nanowire is studied by incorporating the disordered regions on\neither side of the wall. It is found that spin-dependent scattering in these\nregions increases the domain wall magnetoconductance as compared to the effect\nfound by considering only the scattering inside the wall. This increase is most\ndramatic in the narrow wall limit, but remains significant for wide walls.",
        "positive": "Real space first-principles derived semiempirical pseudopotentials\n  applied to tunneling magnetoresistance: In this letter we present a real space density functional theory (DFT)\nlocalized basis set semi-empirical pseudopotential (SEP) approach. The method\nis applied to iron and magnesium oxide, where bulk SEP and local spin density\napproximation (LSDA) band structure calculations are shown to agree within\napproximately 0.1 eV. Subsequently we investigate the qualitative\ntransferability of bulk derived SEPs to Fe/MgO/Fe tunnel junctions. We find\nthat the SEP method is particularly well suited to address the tight binding\ntransferability problem because the transferability error at the interface can\nbe characterized not only in orbital space (via the interface local density of\nstates) but also in real space (via the system potential). To achieve a\nquantitative parameterization, we introduce the notion of ghost semi-empirical\npseudopotentials extracted from the first-principles calculated Fe/MgO bonding\ninterface. Such interface corrections are shown to be particularly necessary\nfor barrier widths in the range of 1 nm, where interface states on opposite\nsides of the barrier couple effectively and play a important role in the\ntransmission characteristics. In general the results underscore the need for\nseparate tight binding interface and bulk parameter sets when modeling\nconduction through thin heterojunctions on the nanoscale."
    },
    {
        "anchor": "Reshaped Weyl fermionic dispersions driven by Coulomb interactions in\n  MoTe2: We report the direct evidence of impacts of the Coulomb interaction in a\nprototypical Weyl semimetal, MoTe2, that alter its bare bands in a wide range\nof energy and momentum. Our quasiparticle interference patterns measured using\nscanning tunneling microscopy are shown to match the joint density of states of\nquasiparticle energy bands including momentum-dependent self-energy\ncorrections, while electronic energy bands based on the other simpler local\napproximations of the Coulomb interaction fail to explain neither the correct\nnumber of quasiparticle pockets nor shape of their dispersions observed in our\nspectrum. With this, we predict a transition between type-I and type-II Weyl\nfermions with doping and resolve its disparate quantum oscillation experiments,\nthus highlighting the critical roles of Coulomb interactions in layered Weyl\nsemimetals.",
        "positive": "Structural analysis of polycrystalline graphene systems by Raman\n  spectroscopy: A theoretical model supported by experimental results explains the dependence\nof the Raman scattering signal on the evolution of structural parameters along\nthe amorphization trajectory of polycrystalline graphene systems. Four\nparameters rule the scattering efficiencies, two structural and two related to\nthe scattering dynamics. With the crystallite sizes previously defined from\nX-ray diffraction and microscopy experiments, the three other parameters (the\naverage grain boundaries width, the phonon coherence length, and the electron\ncoherence length) are extracted from the Raman data with the geometrical model\nproposed here. The broadly used intensity ratio between the C-C stretching (G\nband) and the defect-induced (D band) modes can be used to measure crystallite\nsizes only for samples with sizes larger than the phonon coherence length,\nwhich is found equal to 32 nm. The Raman linewidth of the G band is ideal to\ncharacterize the crystallite sizes below the phonon coherence length, down to\nthe average grain boundaries width, which is found to be 2.8 nm. \"Ready-to-use\"\nequations to determine the crystallite dimensions based on Raman spectroscopy\ndata are given."
    },
    {
        "anchor": "Magnetic edge states in Aharonov-Bohm graphene quantum rings: The effect of electron-electron interaction on the electronic structure of\nAharonov-Bohm (AB) graphene quantum rings (GQRs) is explored theoretically\nusing the single-band tight-binding Hamiltonian and the mean-field Hubbard\nmodel. The electronic states and magnetic properties of hexagonal, triangular\nand circular GQRs with different sizes and zigzag edge terminations are\nstudied. The results show that, although the AB oscillations in the all types\nof nanoring are affected by the interaction, the spin splitting in the AB\noscillations strongly depends on the geometry and the size of graphene\nnanorings. We found that the total spin of hexagonal and circular rings is zero\nand therefore, no spin splitting can be observed in the AB oscillations.\nHowever, the non-zero magnetization of the triangular rings breaks the\ndegeneracy between spin-up and spin-down electrons, which produces\nspin-polarized AB oscillations.",
        "positive": "Dynamics of Quantum Hall Interfaces: A quantum Hall (QH) interface is different from an ordinary QH edge, as the\nlatter has its location determined by the confining potential, while the former\ncan be unpinned and behave like a free string. In this paper, we demonstrate\nthis difference by studying three different interfaces formed by (i) the\nLaughlin state and the vacuum, (ii) the Pfaffian state and the vacuum, and\n(iii) the Pfaffian and the anti-Pfaffian states. We find that string-like\ninterfaces propagating freely in the QH system lead to very different dynamical\nproperties from edges. This qualitative difference gives rise to fascinating\nnew physics and suggests a new direction in future research on QH physics. We\nalso discuss briefly possible analogies between QH interfaces and concepts in\nstring theory."
    },
    {
        "anchor": "Controlled catalyst transfer polymerization in graphene nanoribbon\n  synthesis: Exercising direct control over the unusual electronic structures arising from\nquantum confinement effects in graphene nanoribbons (GNRs) - atomically defined\nquasi one-dimensional (1D) strips of graphene - is intimately linked to\ngeometric boundary conditions imposed by the bonding within the ribbon. Besides\ncomposition and position of substitutional dopant atoms, the symmetry of the\nunit cell, the width, length, and termination of a GNR are integral factors\nthat collectively can give rise to highly tuneable semiconductors, innate\nmetallicity arising from topological zero-mode engineering, or magnetic\nordering in spin-polarized lattices. Here we present a rational design that\nintegrates each of these interdependent variables within a modular bottom-up\nsynthesis. Our hybrid chemical approach relies on a catalyst transfer\npolymerization (CTP) that establishes uniform control over length, width, and\nend-groups. Complemented by a surface-assisted cyclodehydrogenation step,\nuniquely enabled by matrix-assisted direct (MAD) transfer protocols, geometry\nand functional handles encoded in a polymer template are faithfully mapped onto\nthe structure of the corresponding GNR. Bond-resolved scanning tunnelling\nmicroscopy (BRSTM) and spectroscopy (STS) validate the robust correlation\nbetween polymer template design and GNR electronic structure and provide a\nuniversal and modular platform for the systematic exploration and seamless\nintegration of functional GNRs with integrated circuit architectures.",
        "positive": "Flux-tunable heat sink for quantum electric circuits: Superconducting microwave circuits show great potential for practical quantum\ntechnological applications such as quantum information processing. However,\nfast and on-demand initialization of the quantum degrees of freedom in these\ndevices remains a challenge. Here, we experimentally implement a tunable heat\nsink that is potentially suitable for the initialization of superconducting\nqubits. Our device consists of two coupled resonators. The first resonator has\na high quality factor and a fixed frequency whereas the second resonator is\ndesigned to have a low quality factor and a tunable resonance frequency. We\nengineer the low quality factor using an on-chip resistor and the frequency\ntunability using a superconducting quantum interference device. When the two\nresonators are in resonance, the photons in the high-quality resonator can be\nefficiently dissipated. We show that the corresponding loaded quality factor\ncan be tuned from above $10^5$ down to a few thousand at 10 GHz in good\nquantitative agreement with our theoretical model."
    },
    {
        "anchor": "Condensate Fragmentation in a New Exactly Solvable Model for Confined\n  Bosons: Based on Richardson's exact solution of the pairing model and the Gaudin\nmodel for spin systems we derive a new class of exactly solvable models for\nfinite boson system. As an example we solve a particular hamiltonian which\ndisplays a transition to a fragmented condensate for repulsive pairing\ninteractions.",
        "positive": "Single Quantum Level Electron Turnstile: We report on the realization of a single-electron source, where current is\ntransported through a single-level quantum dot (Q), tunnel-coupled to two\nsuperconducting leads (S). When driven with an ac gate voltage, the experiment\ndemonstrates electron turnstile operation. Compared to the more conventional\nsuperconductor - normal metal - superconductor turnstile, our SQS device\npresents a number of novel properties, including higher immunity to the\nunavoidable presence of non-equilibrium quasiparticles in superconducting\nleads. In addition, we demonstrate its ability to deliver electrons with a very\nnarrow energy distribution."
    },
    {
        "anchor": "\"Water-cycle\" mechanism for writing and erasing nanostructures at the\n  LaAlO3/SrTiO3 interface: Nanoscale control of the metal-insulator transition in LaAlO3/ SrTiO3\nheterostructures can be achieved using local voltages applied by a conductive\natomic-force microscope probe. One proposed mechanism for the writing and\nerasing process involves an adsorbed H2O layer at the top LaAlO3 surface. In\nthis picture, water molecules dissociates into OH- and H+ which are then\nselectively removed by a biased AFM probe. To test this mechanism, writing and\nerasing experiments are performed in a vacuum AFM using various gas mixtures.\nWriting ability is suppressed in those environments where H2O is not present.\nThe stability of written nanostructures is found to be strongly associated with\nthe ambient environment. The self-erasure process in air can be strongly\nsuppressed by creating a modest vacuum or replacing the humid air with dry\ninert gas. These experiments provide strong constraints for theories of both\nthe writing process as well as the origin of interfacial conductance.",
        "positive": "On critical properties of Berry curvature in Kitaev honeycomb model: We analyse the Kitaev honeycomb model, by means of the Berry curvature with\nrespect to Hamiltonian parameters. We concentrate on the ground-state\nvortex-free sector, which allows us to exploit an appropriate Fermionisation\ntechnique. The parameter space includes a time-reversal breaking term which\nprovides an analytical headway to study the curvature in phases in which it\nwould otherwise vanish. The curvature is then analysed in the limit in which\nthe time-reversal-symmetry-breaking perturbation vanishes. This provides\nremarkable information about the topological phase transitions of the model. A\nnon-critical behaviour is found in the Berry curvature itself, which shows a\ndistinctive behaviour in the different phases. The analysis of the first\nderivative shows a critical behaviour around the transition point."
    },
    {
        "anchor": "Sub $k_B T$ micro-electromechanical irreversible logic gate: In modern computers, computation is performed by assembling together sets of\nlogic gates. Popular gates like AND, OR, XOR, processing two logic inputs and\nyielding one logic output, are often addressed as irreversible logic gates\nwhere the sole knowledge of the output logic value, is not sufficient to infer\nthe logic value of the two inputs. Such gates are usually believed to be\nbounded to dissipate a finite minimum amount of energy determined by the\ninput-output information difference. Here we show that this is not necessarily\nthe case, by presenting an experiment where a OR logic gate, realized with a\nmicro electromechanical cantilever, is operated with energy well below the\nexpected limit, provided the operation is slow enough and frictional phenomena\nare properly addressed.",
        "positive": "Nonequilibrium conductance through a benzene molecule in the Kondo\n  regime: Starting from exact eigenstates for a symmetric ring, we derive a low-energy\neffective generalized Anderson Hamiltonian which contains two spin doublets\nwith opposite momenta and a singlet for the neutral molecule. For benzene, the\nsinglet (doublets) represent the ground state of the neutral (singly charged)\nmolecule. We calculate the non-equilibrium conductance through a benzene\nmolecule, doped with one electron or a hole (i.e. in the Kondo regime), and\nconnected to two conducting leads at different positions. We solve the problem\nusing the Keldysh formalism and the non-crossing approximation (NCA). When the\nleads are connected in the \\emph{para} position (at 180 degrees), the model is\nequivalent to the ordinary impurity Anderson model and its known properties are\nrecovered. For other positions, there is a partial destructive interference in\nthe cotunneling processes involving the two doublets and as a consequence, the\nKondo temperature and the height and width of the central peak (for bias\nvoltage $V_b$ near zero) of the differential conductance $G=dI/dV_b$ (where $I$\nis the current) are reduced. In addition, two peaks at finite $V_b$ appear. We\nstudy the position of these peaks, the temperature dependence of $G$ and the\nspectral densities. Our formalism can also be applied to carbon nanotube\nquantum dots with intervalley mixing."
    },
    {
        "anchor": "Odd-frequency Superconductivity Revealed by Thermopower: Superconductivity is characterized by a nonvanishing superconducting pair\namplitude. It has a definite symmetry in spin, momentum and frequency (time).\nWhile the spin and momentum symmetry have been probed experimentally for\ndifferent classes of superconductivity, the odd-frequency nature of certain\nsuperconducting correlations has not been demonstrated yet in a direct way.\nHere we propose the thermopower as an unambiguous way to assess odd-frequency\nsuperconductivity. This is possible since the thermoelectric coefficient given\nby Andreev-like processes is only finite in the presence of odd-frequency\nsuperconductivity. We illustrate our general findings with a simple example of\na superconductor-quantum dot-ferromagnet hybrid.",
        "positive": "An analytical model of fractional overshooting: We predict resistance anomalies to be observed at high mobility two\ndimensional electron systems (2DESs) in the fractional quantized Hall regime,\nwhere the narrow (L <10 ?m) Hall bar is defined by top gates. An analytic\ncalculation scheme is used to describe the formation of integral and fractional\nincompressible strips. We incorporate the screening properties of the 2DES,\ntogether with the effects of perpendicular magnetic field, to calculate the\neffective widths of the current carrying channels. The many-body effects are\nincluded to our calculation scheme through the energy gap obtained from the\nwell accepted formulation of the composite fermions. We show that, the\nfractional incompressible strips at the edges, assuming different filling\nfactors, become evanescent and co-exist at certain magnetic field intervals\nyielding an overshoot at the Hall resistance. Similar to that of the integral\nquantized Hall effect. We also provide a mechanism to explain the absence of\n1/3 state at the Fabry-Perot interference experiments. Yet, an un-investigated\nsample design is proposed to observe and enhance the fragile effects like\ninterference and overshooting based on our analytical model."
    },
    {
        "anchor": "Magnetic field driven dynamics in twisted bilayer artificial spin ice at\n  superlattice angles: Geometrical designs of interacting nanomagnets have been studied extensively\nin the form of two dimensional arrays called artificial spin ice. These systems\nare usually designed to create geometrical frustration and are of interest for\nthe unusual and often surprising phenomena that can emerge. Advanced\nlithographic and element growth techniques have enabled the realization of\ncomplex designs that can involve elements arranged in three dimensions. Using\nnumerical simulations employing the dumbbell approximation, we examine possible\nmagnetic behaviours for bilayer artificial spin ice (BASI) in which the\nindividual layers are rotated with respect to one another. The goal is to\nunderstand how magnetization dynamics are affected by long-range dipolar\ncoupling that can be modified by varying the layer separation and layer\nalignment through rotation. We consider bilayers where the layers are both\neither square or pinwheel arrangements of islands. Magnetic reversal processes\nare studied and discussed in terms of domain and domain wall configurations of\nthe magnetic islands. Unusual magnetic ordering is predicted for special angles\nwhich define lateral spin superlattices for the bilayer systems.",
        "positive": "Conductance asymmetry in proximitized magnetic topological insulator\n  junctions with Majorana modes: We theoretically discuss electronic transport via Majorana states in magnetic\ntopological insulator-superconductor junctions with an asymmetric split of the\napplied bias voltage. We study normal-superconductor-normal (NSN) junctions\nmade of narrow (wire-like) or wide (film-like) magnetic topological insulator\nslabs with a central proximitized superconducting sector. The occurrence of\ncharge non-conserving Andreev processes entails a nonzero conductance related\nto an electric current flowing to ground from the proximitized sector of the\nNSN junction. We show that topologically-protected Majorana modes require an\nantisymmetry of this conductance with respect to the point of equally split\nbias voltage across the junction."
    },
    {
        "anchor": "The Franz-Keldysh effect revisited: Electroabsorption including\n  interband coupling and excitonic effects: We study the linear optical absorption of bulk semiconductors in the presence\nof a homogeneous constant (dc) electric field with an approach suitable for\nincluding excitonic effects while working with many-band models. The absorption\ncoefficient is calculated from the time evolution of the interband polarization\nexcited by an optical pulse. We apply the formalism to a numerical calculation\nfor GaAs using a 14-band $\\textbf{k} \\cdot \\textbf{p}$ model, which allows us\nto properly include interband coupling, and the exchange self-energy to account\nfor the excitonic effects due to the electron-hole interaction. The Coulomb\ninteraction enhances the features of the absorption coefficient captured by the\n$\\textbf{k} \\cdot \\textbf{p}$ model. We consider the dependence of the\nenhancement on the strength of the dc field and the polarization of the optical\nfield.",
        "positive": "Domain Wall-Magnetic Tunnel Junction Spin Orbit Torque Devices and\n  Circuits for In-Memory Computing: There are pressing problems with traditional computing, especially for\naccomplishing data-intensive and real-time tasks, that motivate the development\nof in-memory computing devices to both store information and perform\ncomputation. Magnetic tunnel junction (MTJ) memory elements can be used for\ncomputation by manipulating a domain wall (DW), a transition region between\nmagnetic domains. But, these devices have suffered from challenges: spin\ntransfer torque (STT) switching of a DW requires high current, and the multiple\netch steps needed to create an MTJ pillar on top of a DW track has led to\nreduced tunnel magnetoresistance (TMR). These issues have limited experimental\nstudy of devices and circuits. Here, we study prototypes of three-terminal\ndomain wall-magnetic tunnel junction (DW-MTJ) in-memory computing devices that\ncan address data processing bottlenecks and resolve these challenges by using\nperpendicular magnetic anisotropy (PMA), spin-orbit torque (SOT) switching, and\nan optimized lithography process to produce average device tunnel\nmagnetoresistance TMR = 164%, resistance-area product RA = 31\n{\\Omega}-{\\mu}m^2, close to the RA of the unpatterned film, and lower switching\ncurrent density compared to using spin transfer torque. A two-device circuit\nshows bit propagation between devices. Device initialization variation in\nswitching voltage is shown to be curtailed to 7% by controlling the DW initial\nposition, which we show corresponds to 96% accuracy in a DW-MTJ full adder\nsimulation. These results make strides in using MTJs and DWs for in-memory and\nneuromorphic computing applications."
    },
    {
        "anchor": "Quantum Sensing of Antiferromagnetic Magnon Two-Mode Squeezed Vacuum: N\\'eel ordered antiferromagnets exhibit two-mode squeezing such that their\nground state is a nonclassical superposition of magnon Fock states. Here we\ntheoretically demonstrate that antiferromagnets can couple to spin qubits via\ndirect dispersive interaction stemming from, e.g., interfacial exchange. We\ndemonstrate that this kind of coupling induces a magnon number dependent level\nsplitting of the excited state resulting in multiple system excitation\nenergies. This series of level splittings manifests itself as nontrivial\nexcitation peaks in qubit spectroscopy thereby revealing the underlying\nnonclassical magnon composition of the antiferromagnetic quantum state. By\nappropriately choosing the drive or excitation energy, the magnonic state can\nbe controlled via the qubit, suggesting that Fock states of magnon pairs can be\ngenerated deterministically. This enables achieving states useful for quantum\ncomputing and quantum information science protocols.",
        "positive": "Highly directed emission from self-assembled quantum dots into guided\n  modes in disordered photonic crystal waveguides: We explore the dynamics and directionality of spontaneous emission from\nself-assembled In(Ga)As quantum dots into TE-polarised guided modes in GaAs\ntwo-dimensional photonic crystal waveguides. The local group velocity of the\nguided waveguide mode is probed, with values as low as $\\sim 1.5\\%\\times c$\nmeasured close to the slow-light band edge. By performing complementary\ncontinuous wave and time-resolved measurements with detection along, and\nperpendicular to the waveguide axis we probe the fraction of emission into the\nwaveguide mode ($\\beta$-factor). For dots randomly positioned within the unit\ncell of the photonic crystal waveguide our results show that the emission rate\nvaries from $\\geq 1.55$ $ns^{-1}$ close to the slow-light band edge to $\\leq\n0.25$ $ns^{-1}$ within the two-dimensional photonic bandgap. We measure an\naverage Purcell-factor of $\\sim 2\\times$ for dots randomly distributed within\nthe waveguide and maximum values of $\\beta\\sim 90 \\%$ close to the slow light\nband edge. Spatially resolved measurements performed by exciting dots at a well\ncontrolled distance $0-45$ {\\mu}m from the waveguide facet highlight the impact\nof disorder on the slow-light dispersion. Although disorder broadens the\nspectral width of the slow light region of the waveguide dispersion from\n$\\delta E_{d}\\leq 0.5$ meV to $>6$ meV, we find that emission is nevertheless\nprimarily directed into propagating waveguide modes. The ability to control the\nrate and directionality of emission from isolated quantum emitters by placing\nthem in a tailored photonic environment provides much promise for the use of\nslow-light phenomena to realise efficient single photon sources for quantum\noptics in a highly integrated setting."
    },
    {
        "anchor": "Maximal symetrization and reduction of fields: application to\n  wavefunctions in solid state nanostructures: A novel general formalism for the maximal symetrization and reduction of\nfields (MSRF) is proposed and applied to wavefunctions in solid state\nnanostructures. Its primary target is to provide an essential tool for the\nstudy and analysis of the electronic and optical properties of semiconductor\nquantum heterostructures with relatively high point-group symmetry, and studied\nwith the $k\\cdot p$ formalism. Nevertheless the approach is valid in a much\nlarger framework than $k\\cdot p$ theory, it is applicable to arbitrary systems\nof coupled partial differential equations (e.g. strain equations or Maxwell\nequations). For spinless problems (scalar equations), one can use a systematic\nSpatial Domain Reduction (SDR) technique which allows, for every irreducible\nrepresentation, to reduce the set of equations on a minimal domain with\nautomatic incorporation of the boundary conditions at the border, which are\nshown to be non-trivial in general. For a vectorial or spinorial set of\nfunctions, the SDR technique must be completed by the use of an optimal basis\nin vectorial or spinorial space (in a crystal we call it the Optimal Bloch\nfunction Basis - OBB). The advantages are numerous: sharper insights on the\nsymmetry properties of every eigenstate, minimal coupling schemes, analytically\nand computationally exploitable at the component function level, minimal\ncomputing domains. The formalism can be applied also as a postprocessing\noperation, offering all subsequent analytical and computationnal advantages of\nsymmetrization. The specific case of a quantum wire (QWRs) with $C_{3v}$ point\ngroup symmetry is used as a concrete illustration of the application of MSRF.",
        "positive": "Magnetic phase transitions in two-dimensional two-valley semiconductors\n  with in-plane magnetic field: A two-dimensional electron gas (2DEG) in two-valley semiconductors has two\ndiscrete degrees of freedom given by the spin and valley quantum numbers. We\nanalyze the zero-temperature magnetic instabilities of two-valley\nsemiconductors with SOI, in-plane magnetic field, and electron-electron\ninteraction. The interplay of an applied in-plane magnetic field and the SOI\nresults in non-collinear spin quantization in different valleys. Together with\nthe exchange intervalley interaction this results in a rich phase diagram\ncontaining four non-trivial magnetic phases. The negative non-analytic cubic\ncorrection to the free energy, which is always present in an interacting 2DEG,\nis responsible for first order phase transitions. Here, we show that non-zero\nground state values of the order parameters can cut this cubic non-analyticity\nand drive certain magnetic phase transitions second order. We also find two\ntri-critical points at zero temperature which together with the line of second\norder phase transitions constitute the quantum critical sector of the phase\ndiagram. The phase transitions can be tuned externally by electrostatic gates\nor by the in-plane magnetic field."
    },
    {
        "anchor": "Long-range coherent coupling in a quantum dot array: Controlling long-range quantum correlations is central to quantum computation\nand simulation. In quantum dot arrays, experiments so far rely on\nnearest-neighbour couplings only, and inducing long-range correlations requires\nsequential local operations. Here we show that two distant sites can be tunnel\ncoupled directly. The coupling is mediated by virtual occupation of an\nintermediate site, with a strength that is controlled via the energy detuning\nof this site. It permits a single charge to oscillate coherently between the\nouter sites of a triple dot array without passing through the middle, as\ndemonstrated through the observation of Landau-Zener-St\\\"uckelberg\ninterference. The long-range coupling significantly improves the prospects of\nfault-tolerant quantum computation using quantum dot arrays and opens up new\navenues for performing quantum simulations in nanoscale devices.",
        "positive": "Nanoscaled magnon transistor based on stimulated three-magnon splitting: Magnonics is a rapidly growing field, attracting much attention for its\npotential applications in data transport and processing. Many individual\nmagnonic devices have been proposed and realized in laboratories. However, an\nintegrated magnonic circuit with several separate magnonic elements has yet not\nbeen reported due to the lack of a magnonic amplifier to compensate for\ntransport and processing losses. The magnon transistor reported in [Nat.\nCommun. 5, 4700, (2014)] could only achieve a gain of 1.8, which is\ninsufficient in many practical cases. Here, we use the stimulated three-magnon\nsplitting phenomenon to numerically propose a concept of magnon transistor in\nwhich the energy of the gate magnons at 14.6 GHz is directly pumped into the\nenergy of the source magnons at 4.2 GHz, thus achieving the gain of 9. The\nstructure is based on the 100 nm wide YIG nano-waveguides, a directional\ncoupler is used to mix the source and gate magnons, and a dual-band magnonic\ncrystal is used to filter out the gate and idler magnons at 10.4 GHz frequency.\nThe magnon transistor preserves the phase of the signal and the design allows\nintegration into a magnon circuit."
    },
    {
        "anchor": "PT-Symmetric magnetic Chaos in cavity magnomechanics: Here, we research a novel cavity magnomechanical system, where magnon driven\nby a microwave field couples with a phonon mode with a nonlinear\nmagneostrictive interaction (radiation pressure-like). Based on this\ninteraction, we numerically demonstrate PT-symmetric chaos in this system. With\nonly one monochrome driving, the chaotic threshold is lowered to a rather low\nlevels, this is due to the dynamical enhancement of nonlinearity in the\nPT-symmetry broken phase. Moreover, by simply manipulating the phase transition\nbetween PT-symmetry phase and PT-symmetry broken phase, we can switch the\nsystem between into and out of chaotic regimes. Our work may broaden the cavity\nmagnomechanics and provide a promising application for magnetic chaos-related\nsecurity communications.",
        "positive": "Moir\u00e9 lattice-induced formation and tuning of hybrid dipolar excitons\n  in twisted WS$_2$/MoSe$_2$ heterobilayers: Moir\\'e superlattices formed in van der Waals bilayers have enabled the\ncreation and manipulation of new quantum states, as is exemplified by the\ndiscovery of superconducting and correlated insulating states in twisted\nbilayer graphene near the magic angle. Twisted bilayer semiconductors may lead\nto tunable exciton lattices and topological states, yet signatures of moir\\'e\nexcitons have been reported only in closely angularly-aligned bilayers. Here we\nreport tuning of moir\\'e lattice in WS$_{2}$ /MoSe$_{2}$ bilayers over a wide\nrange of twist angles, leading to the continuous tuning of moir\\'e lattice\ninduced interlayer excitons and their hybridization with optically bright\nintralayer excitons. A pronounced revival of the hybrid excitons takes place\nnear commensurate twist angles, 21.8{\\deg}and 38.2{\\deg}, due to interlayer\ntunneling between states connected by a moir\\'e reciprocal lattice vector. From\nthe angle dependence, we obtain the effective mass of the interlayer excitons\nand the electron inter-layer tunneling strength. These findings pave the way\nfor understanding and engineering rich moir\\'e-lattice induced phenomena in\nangle-twisted semiconductor van dar Waals heterostructures."
    },
    {
        "anchor": "Dynamics of noncollinear antiferromagnetic textures driven by spin\n  current injection: We present a theoretical formalism to address the dynamics of textured,\nnoncolliear antiferromagnets subject to spin current injection. We derive\nsine-Gordon type equations of motion for the antiferromagnets, which are\napplicable to technologically important antiferromagnets such as Mn3Ir and\nMn3Sn, and enables an analytical approach to domain wall dynamics in those\nmaterials. We obtain the expression for domain wall velocity, which is\nestimated to reach around 1 km/s in Mn3Ir by exploiting spin Hall effect with\nelectric current density around 10^11A/m^2.",
        "positive": "Observation of measurement-induced entanglement and quantum trajectories\n  of remote superconducting qubits: The creation of a quantum network requires the distribution of coherent\ninformation across macroscopic distances. We demonstrate the entanglement of\ntwo superconducting qubits, separated by more than a meter of coaxial cable, by\ndesigning a joint measurement that probabilistically projects onto an entangled\nstate. By using a continuous measurement scheme, we are further able to observe\nsingle quantum trajectories of the joint two-qubit state, confirming the\nvalidity of the quantum Bayesian formalism for a cascaded system. Our results\nallow us to resolve the dynamics of continuous projection onto the entangled\nmanifold, in quantitative agreement with theory."
    },
    {
        "anchor": "Rash spin-orbit interaction in graphene and graphene zigzag nano-ribbons: We investigate the effects of Rashba spin-orbit interactions on the\nelectronic band-structure and corresponding wave-functions of graphene. By\nexactly solving a tight-binding model Hamiltonian we obtain the expected\nsplitting of the bands -due to the SU(2) spin symmetry breaking- that is\naccompanied by the appearance of additional Dirac points. These points are\noriginated by valence-conduction band crossings. By introducing a convenient\ngauge transformation we study a model for zigzag nanoribbons with RSO\ninteractions. We show that the RSO interactions lifts the quasi-degeneracy of\nthe edge band while introducing a state-dependent spin separation in real\nspace. Calculation of the average magnetization perpendicular to the ribbon\nplane suggest that RSO could be used to produce spin-polarized currents.\nComparisons with the intrinsic spin-orbit (I-SO) interaction proposed to exist\nin graphene are also presented.",
        "positive": "Disorder effects on energy bandgap and electronic transport in\n  graphene-nanomesh-based structures: Using atomistic quantum simulation based on a tight binding model, we\ninvestigate the formation of energy gap Eg of graphene nanomesh (GNM) lattices\nand the transport characteristics of GNM-based electronic devices (single\npotential barrier structure and p-n junction) taking into account the atomic\nedge disorder of holes. We find that the sensitivity of Eg to the lattice\nsymmetry (i.e., the lattice orientation and the hole shape) is significantly\nsuppressed in the presence of the disorder. In the case of strong disorder, the\ndependence of Eg on the neck width is fitted well with the scaling rule\nobserved in experiments [Liang et al., Nano Lett. 10, 2454 (2010)]. Considering\nthe transport characteristics of GNM-based structures, we demonstrate that the\nuse of finite GNM sections in the devices can efficiently improve their\nelectrical performance (i.e., high ON/OFF current ratio, good current\nsaturation and negative differential conductance behaviors). Additionally, if\nthe length of GNM sections is appropriately limited, the detrimental effects of\ndisorder on transport can be avoided to a large extent. Our study provides a\ngood explanation of the available experimental data on GNM energy gap and\nshould be helpful for further investigations of GNM-based devices."
    },
    {
        "anchor": "Precursor configurations and post-rupture evolution of Ag-CO-Ag\n  single-molecule junctions: Experimental correlation analysis and first-principles theory are used to\nprobe the structure and evolution of Ag-CO-Ag single-molecule junctions, both\nbefore the formation, and after the rupture of the junctions. Two dimensional\ncorrelation histograms and conditional histograms demonstrate that prior to the\nsingle-molecule bridge configuration the CO molecule is already bound parallel\nto the Ag single-atom contact. This molecular precursor configuration is\naccompanied by the opening of additional conductance channels compared to the\nsingle-channel transport in pure Ag monoatomic junctions. To investigate the\npost-rupture evolution of the junction we introduce a cross-correlation\nanalysis between the opening and the subsequent closing conductance traces.\nThis analysis implies that the molecule is bound rigidly to the apex of one\nelectrode, and so the same single-molecule configuration is re-established as\nthe junction is closed. The experimental results are confirmed by ab initio\nsimulations of the evolution of contact geometries, transmission eigenvalues\nand scattering wavefunctions.",
        "positive": "Room temperature differential-conductance staircase in suspended\n  graphitic quantum point contacts: This paper has been withdrawn by the author due to pending experimental\ninvestigation to avoid certain potential experimental uncertainty."
    },
    {
        "anchor": "Isospin Pomeranchuk effect and the entropy of collective excitations in\n  twisted bilayer graphene: In condensed matter systems, higher temperatures typically disfavors ordered\nphases leading to an upper critical temperature for magnetism,\nsuperconductivity, and other phenomena. A notable exception is the Pomeranchuk\neffect in 3He, in which the liquid ground state freezes upon increasing the\ntemperature due to the large entropy of the paramagnetic solid phase. Here we\nshow that a similar mechanism describes the finite temperature dynamics of spin\nand valley-isospins in magic-angle twisted bilayer graphene. Most strikingly a\nresistivity peak appears at high temperatures near superlattice filling factor\nnu = -1, despite no signs of a commensurate correlated phase appearing in the\nlow-temperature limit. Tilted field magnetotransport and thermodynamic\nmeasurements of the inplane magnetic moment show that the resistivity peak is\nadiabatically connected to a finite-field magnetic phase transition at which\nthe system develops finite isospin polarization. These data are suggestive of a\nPomeranchuk-type mechanism, in which the entropy of disordered isospin moments\nin the ferromagnetic phase stabilizes it relative to an isospin unpolarized\nFermi liquid phase at elevated temperatures. Measurements of the entropy, S/kB\nindeed find it to be of order unity per unit cell area, with a measurable\nfraction that is suppressed by an in-plane magnetic field consistent with a\ncontribution from disordered physical spins. In contrast to 3He, however, no\ndiscontinuities are observed in the thermodynamic quantities across this\ntransition. Our findings imply a small isospin stiffness, with implications for\nthe nature of finite temperature transport as well as the mechanisms underlying\nisospin ordering and superconductivity in twisted bilayer graphene and related\nsystems.",
        "positive": "Tunable spectral narrowing enabling the functionality of graphene qubit\n  circuits at room temperature: Electrically controllable quantum coherence in quantum dot clusters and\narrays based on graphene stripes with zigzag atomic edges (ZZ-stripes) is\nstudied using the Dirac equation and S-matrix technique. We find that\nrespective multiqubit circuits promise stable operation up to room temperatures\nwhen the coherence time is prolonged up by a few orders of magnitude through\nthe intrinsic spectral narrowing owing to electron transport between at bands\nin adjacent sections. Respectively, the coupling of qubits to a noisy\nenvironment is diminished, while the inelastic electron-phonon scattering is\nsuppressed. The Stark splitting technique enables a broad range of operations\nsuch as all{electrical tuning of the energy level positions and width, level\nsplitting, controlling of the inter-qubit coupling, and the coherence time. At\nthe resonant energies, the phase coherence spreads over thousands of periods.\nSuch phenomena potentially can be utilized in quantum computing and\ncommunication applications at room temperature."
    },
    {
        "anchor": "An information theoretic model for the linear and nonlinear dissipative\n  structures in irradiated single-walled carbon nanotubes: Experiments with irradiated single-walled carbon nanotubes are shown to\ngenerate a set of probability distribution functions and to derive a set of\ninformation theoretic entropy-based parameters. Energetic Cs+ ions initiate\nlinear collision cascades and nonlinear thermal spikes in single-walled carbon\nnanotubes. The probability distribution functions are constructed from the\nnormalized experimental yields of the sputtered atoms and clusters. The\ninformation or Shannon entropy and fractal dimension are evaluated for each of\nthe emitted species. Along with the fractal dimension, the information is used\nto identify and distinguish the energy dissipation processes that generate\nconditions for monatomic sputtering and clusters emissions.",
        "positive": "Photon echo transients from an inhomogeneous ensemble of semiconductor\n  quantum dots: An ensemble of quantum dot excitons may be used for coherent information\nmanipulation. Due to the ensemble inhomogeneity any optical information\nretrieval occurs in form of a photon echo. We show that the inhomogeneity can\nlead to a significant deviation from the conventional echo timing sequence.\nVariation of the area of the initial rotation pulse, which generates excitons\nin a dot sub-ensemble only, reveals this complex picture of photon echo\nformation. We observe a retarded echo for {\\pi}/2 pulses, while for 3{\\pi}/2\nthe echo is advanced in time as evidenced through monitoring the Rabi\noscillations in the time-resolved photon echo amplitude from (In,Ga)As/GaAs\nself-assembled quantum dot structures and confirmed by detailed calculations."
    },
    {
        "anchor": "Temporal plasmonics: Fano and Rabi regimes in the time domain in metal\n  nanostructures: The Fano and Rabi models represent remarkably common effects in optics. Here\nwe study the coherent time dynamics of plasmonic systems exhibiting Fano and\nRabi resonances. We demonstrate that these systems show fundamentally different\ndynamics. A system with a Fano resonance displays at most one temporal beat\nunder pulsed excitation, whereas a system in the Rabi regime may have any\nnumber of beats. Remarkably, the Fano-like systems show time dynamics with very\ncharacteristic coherent tails despite the strong decoherence that is intrinsic\nfor such systems. The coherent Fano and Rabi dynamics that we predicted can be\nobserved in plasmonic nanocrystal dimers in time-resolved experiments. Our\nstudy demonstrates that such coherent temporal plasmonics includes nontrivial\nand characteristic relaxation behaviors and presents an interesting direction\nto develop with further research.",
        "positive": "Fast Room-Temperature Phase Gate on a Single Nuclear Spin in Diamond: Nuclear spins support long lived quantum coherence due to weak coupling to\nthe environment, but are difficult to rapidly control using nuclear magnetic\nresonance (NMR) as a result of the small nuclear magnetic moment. We\ndemonstrate a fast ~ 500 ns nuclear spin phase gate on a 14N nuclear spin qubit\nintrinsic to a nitrogen-vacancy (NV) center in diamond. The phase gate is\nenabled by the hyperfine interaction and off-resonance driving of electron spin\ntransitions. Repeated applications of the phase gate bang-bang decouple the\nnuclear spin from the environment, locking the spin state for up to ~ 140\nmicroseconds."
    },
    {
        "anchor": "Heat-mode excitation in a proximity superconductor: Mesoscopic superconductivity deals with various quasiparticle excitation\nmodes, only one of them -- the charge-mode -- being directly accessible for\nconductance measurements due to the imbalance in populations of quasi-electron\nand quasihole excitation branches. Other modes carrying heat or even spin,\nvalley etc. currents populate the branches equally and are charge-neutral,\nwhich makes them much harder to control. This noticeable gap in the\nexperimental studies of mesoscopic non-equilibrium superconductivity can be\nfilled by going beyond the conventional DC transport measurements and\nexploiting spontaneous current fluctuations. Here, we perform such an\nexperiment and investigate the transport of heat in an open hybrid device based\non a superconductor proximitized InAs nanowire. Using shot noise measurements,\nwe investigate sub-gap Andreev heat guiding along the superconducting interface\nand fully characterize it in terms of the thermal conductance on the order of\n$G_\\mathrm{th}\\sim e^2/h$, tunable by a back gate voltage. Understanding of the\nheat-mode also uncovers its implicit signatures in the non-local charge\ntransport. Our experiments open a direct pathway to probe generic\ncharge-neutral excitations in superconducting hybrids.",
        "positive": "Topological invariant of multilayer Haldane models with irregular\n  stackings: We study multilayer Haldane models with irregular type of stacking,\nconsidering the nearest interlayer hopping. We prove that the value of the\ntopological invariant is equal to the number of layers times the value of the\ntopological invariant of monolayer Haldane model, regardless of stacking type,\nand interlayer hoppings do not induce gap closing and phase transitions."
    },
    {
        "anchor": "Transport across a system with three p-wave superconducting wires:\n  effects of Majorana modes and interactions: We study the effects of Majorana modes and interactions between electrons on\ntransport in a one-dimensional system with a junction of three p-wave\nsuperconductors (SCs) which are connected to normal metal leads. For\nsufficiently long SCs, there are zero energy Majorana modes at the junctions\nbetween the SCs and the leads,and, depending on the signs of the p-wave\npairings in the three SCs, there can also be one or three Majorana modes at the\njunction of the three SCs. We show that the various sub-gap conductances have\npeaks occurring at the energies of all these modes; we therefore get a rich\npattern of conductance peaks. Next, we use a renormalization group approach to\nstudy the scattering matrix of the system at energies far from the SC gap. The\nfixed points of the renormalization group flows and their stabilities are\nstudied; we find that the scattering matrix at the stable fixed point is highly\nsymmetric even when the microscopic scattering matrix and the interaction\nstrengths are not symmetric. We discuss the implications of this for the\nconductances. Finally we propose an experimental realization of this system\nwhich can produce different signs of the p-wave pairings in the different SCs.",
        "positive": "First Experimental Demonstration of Gate-all-around III-V MOSFET by\n  Top-down Approach: The first inversion-mode gate-all-around (GAA) III-V MOSFETs are\nexperimentally demonstrated with a high mobility In0.53Ga0.47As channel and\natomic-layer-deposited (ALD) Al2O3/WN gate stacks by a top-down approach. A\nwell-controlled InGaAs nanowire release process and a novel ALD high-k/metal\ngate process has been developed to enable the fabrication of III-V GAA MOSFETs.\nWell-behaved on-state and off-state performance has been achieved with channel\nlength (Lch) down to 50nm. A detailed scaling metrics study (S.S., DIBL, VT)\nwith Lch of 50nm - 110nm and fin width (WFin) of 30nm - 50nm are carried out,\nshowing the immunity to short channel effects with the advanced 3D structure.\nThe GAA structure has provided a viable path towards ultimate scaling of III-V\nMOSFETs."
    },
    {
        "anchor": "Landau quantization of multilayer graphene on a Haldane sphere: We consider the problem of multilayer graphene on a Haldane sphere and\ndetermine the Landau level spectrum for this family of systems. This serves as\na generalization of the Landau quantization problem of ordinary\nnon-relativistic Haldane sphere and spherical graphene, or Dirac-like particles\non a sphere. The Hamiltonian is diagonalized in a concise algebraic fashion\nexploiting two mutually commuting SU(2) algebras of the problem. Additionally,\nusing exact wave functions we demonstrate computation of Haldane\npseudopotentials in the second Landau level. These exact solutions add to the\ncurrent toolkits of the numerical studies on fractional quantum Hall effects in\nsystems of graphite multilayers.",
        "positive": "A Nanographene Disk Rotating a single Molecule Gear on a Cu(111) Surface: Lubricants are widely used in macroscopic mechanical systems to reduce\nfriction and wear. However, on the microscopic scale, it is not clear to what\nextent lubricants are beneficial. Therefore, in this study, we consider two\ndiamond solid-state gears at the nanoscale immersed in different lubricant\nmolecules and perform classical MD simulations to investigate the rotational\ntransmission of motion. We find that lubricants can help to synchronize the\nrotational transmission between gears regardless of the molecular species and\nthe center-of-mass distance. Moreover, the influence of the angular velocity of\nthe driving gear is investigated and shown to be related to the bond formation\nprocess between gears."
    },
    {
        "anchor": "Efficient Cooper Pair Splitting Without Coulomb Blockade: For the three-terminal NSN device with single-mode normal terminals and\nwithout Coulomb blockade, we propose an approach which allows us to\nconsistently characterize the device operation as that of a Cooper pair\nsplitter in terms of scattering matrix elements as well as in terms of\nmeasurable quantities. The obtained explicit expression for the splitting\nprobability notably contains the two-particle interference term not available\nfrom conductance measurements. We show that splitting doesn't necessarily rely\non crossed Andreev reflection thus allowing for the unit efficiency at zero\nenergy. Our results imply that the current cross-correlator generally doesn't\nprovide definite measure of splitting.",
        "positive": "Effective Theory of Floquet Topological Transitions: We develop a theory of topological transitions in a Floquet topological\ninsulator, using graphene irradiated by circularly polarized light as a\nconcrete realization. We demonstrate that a hallmark signature of such\ntransitions in a static system, i.e. metallic bulk transport with conductivity\nof order $e^2/h$, is substantially suppressed at some Floquet topological\ntransitions in the clean system. We determine the conditions for this\nsuppression analytically and confirm our results in numerical simulations.\nRemarkably, introducing disorder dramatically enhances this transport by\nseveral orders of magnitude."
    },
    {
        "anchor": "Electron trajectories and magnetotransport in nanopatterned graphene\n  under commensurability conditions: Commensurability oscillations in the magnetotransport of periodically\npatterned systems, emerging from the interplay of cyclotron orbit and the\npattern periodicity, are a benchmark of mesoscopic physics in electron gas\nsystems. Exploiting similar effects in 2D materials would allow exceptional\ncontrol of electron behaviour, but is hindered by the requirement to maintain\nballistic transport over large length scales. Recent experiments have overcome\nthis obstacle and observed distinct magnetoresistance commensurability peaks\nfor perforated graphene sheets (antidot lattices). Interpreting the exact\nmechanisms behind these peaks is of key importance, particularly in graphene\nwhere a range of regimes are accessible by varying the electron density. In\nthis work a fully atomistic, device-based simulation of magnetoresistance\nexperiments allows us to analyse both the resistance peaks and the current flow\nat commensurability conditions. Magnetoresistance spectra are found in\nexcellent agreement with experiment, but we show that a semi-classical\nanalysis, in terms of simple skipping or pinned orbits, is insufficient to\nfully describe the corresponding electron trajectories. Instead, a generalised\nmechanism in terms of states bound to individual antidots, or to groups of\nantidots, is required. Commensurability features are shown to arise when\nscattering between such states is enhanced. The emergence and suppression of\ncommensurability peaks is explored for different antidot sizes, magnetic field\nstrengths and electron densities. The insights gained from our study will guide\nthe design and optimization of future experiments with nanostructured graphene.",
        "positive": "Aharonov-Bohm Exciton Absorption Splitting in Chiral Specific\n  Single-Walled Carbon Nanotubes in Magnetic Fields of up to 78 T: The Ajiki-Ando (A-A) splitting of single-walled carbon nanotubes(SWNT)\noriginating from the Aharanov-Bohm effect was observed in chiral specific SWNTs\nby the magneto-absorption measurements conducted at magnetic fields of up to 78\nT. The absorption spectra from each chirality showed clear A-A splitting of the\n$E_{11}$ optical excitonic transitions. The parameters of both the dark-bright\nexciton energy splitting and the rate of A-A splitting in a magnetic field were\ndetermined for the first time from the well-resolved absorption spectra."
    },
    {
        "anchor": "Correlation between peak-height modulation and phase-lapses in transport\n  through quantum dots: We show that two intriguing features of mesoscopic transport, namely the\nmodulation of Coulomb blockade peak-heights and the transmission phase-lapses\noccurring between subsequent peaks, are closely related. Our analytic arguments\nare corroborated by numerical simulations for chaotic ballistic quantum dots.\nThe correlations between the two properties are experimentally testable. The\nstatistical distribution of the partial-width amplitude, at the heart of the\nprevious relationship, is determined, and its characteristic parameters are\nestimated from simple models.",
        "positive": "Superradiant-like dynamics by electron shuttling on a nuclear-spin\n  island: We investigate superradiant-like dynamics of the nuclear-spin bath in a\nsingle-electron quantum dot, by considering electrons cyclically shuttling\non/off an isotopically enriched `nuclear-spin island'. Assuming a uniform\nhyperfine interaction, we discuss in detail the nuclear spin evolution under\nshuttling and its relation to superradiance. We derive the minimum shuttling\ntime which allows to escape the adiabatic spin evolution. Furthermore, we\ndiscuss slow/fast shuttling under the inhomogeneous field of a nearby\nmicromagnet. Finally, by comparing our scheme to a model with stationary\nquantum dot, we stress the important role played by non-adiabatic shuttling in\nlifting the Coulomb blockade and thus establishing the superradiant-like\nbehavior."
    },
    {
        "anchor": "Entanglement Signature of Hinge Arcs, Fermi Arcs, and Crystalline\n  Symmetry Protection in Higher-Order Weyl Semimetals: The existence of $1/2$ modes in the entanglement spectrum (ES) has been shown\nto be a powerful quantum-informative signature of boundary states of gapped\ntopological phases of matter, e.g., topological insulators and topological\nsuperconductors, where the finite bulk gap allows us to establish a\ncrystal-clear correspondence between $1/2$ modes and boundary states. Here we\ninvestigate the recently proposed higher-order Weyl semimetals (HOWSM), where\nbulk supports gapless higher-order Weyl nodes and boundary supports hinge arcs\nand Fermi arcs. We find that the aim of unambiguously identifying higher-order\nboundary states ultimately drives us to make full use of eigen quantities of\nthe entanglement Hamiltonian: ES as well as Schmidt vectors (entanglement\nwavefunctions, abbr. EWF). We demonstrate that, while both hinge arcs and Fermi\narcs contribute to $1/2$ modes, the EWFs corresponding to hinge arcs and Fermi\narcs are respectively localized on the virtual hinges and surfaces of the\npartition. Besides, by means of various symmetry-breaking partitions, we can\nidentify the minimal crystalline symmetries that protect boundary states.\nTherefore, for gapless topological phases such as HOWSMs, we can combine ES and\nEWF to universally identify boundary states and potential symmetry requirement.\nWhile HOWSMs are prototypical examples of gapless phases, our work sheds light\non general theory of entanglement signature in gapless topological phases of\nmatter.",
        "positive": "Optical manifestation of the Stoner ferromagnetic transition in 2D\n  electron systems: We perform a magneto-optical study of a two-dimensional electron systems\n(2DES) in the regime of the Stoner ferromagnetic instability for even quantum\nHall filling factors on Mg$_x$Zn$_{1-x}$O/ZnO heterostructures. Under\nconditions of Landau-level crossing, caused by enhanced spin susceptibility in\ncombination with the tilting of the magnetic field, the transition between two\nrivaling phases- paramagnetic and ferromagnetic- is traced in terms of optical\nspectra reconstruction. Synchronous sharp transformations are observed both in\nthe photoluminescence structure and parameters of collective excitations upon\ntransition from paramagnetic to ferromagnetic ordering. Based on these\nmeasurements, a phase diagram is constructed in terms of the 2D electron\ndensity and tilt angle of the magnetic field. Apart from stable paramagnetic\nand ferromagnetic phases, an instability region is found at intermediate\nparameters with the Stoner transition occurring at $\\nu\\approx 2$. The spin\nconfiguration in all cases is unambiguously determined by means of inelastic\nlight scattering by spin-sensitive collective excitations. One indicator of the\nspin ordering is the intra-Landau-level spin exciton, which acquires a large\nspectral weight in the ferromagnetic phases. The other - is an abrupt energy\nshift of the intersubband charge density excitation due to change in the\nmany-particle energy contribution upon spin rearrangement. From our analysis of\nphotoluminescence and light scattering data, we estimate the ratio of surface\nareas occupied by the domains of the two phases in the vicinity of a transition\npoint. In addition, the thermal smearing of a phase transition is\ncharacterized."
    },
    {
        "anchor": "Quantum Dynamics of Electron-Nuclei Coupled System in a Double Quantum\n  Dot: Hyperfine interaction of electron spins with nuclear spins, in coupled double\nquantum dots is studied. Results of successive electron spin measurements\nexhibit bunching due to correlations induced via the nuclear spins. Further\nnuclear spins can be purified via conditional electron spin measurements which\nlead to electron spin revivals in the conditional probabilities. The electron\nspin coherence time can be extended via conditional measurements. The results\nare extended to a single electron on a single QD.",
        "positive": "Tunneling current between graphene layers: The physical model that allows to calculate the values of the tunneling\ncurrent be-tween graphene layers is proposed. The tunneling current according\nto the pro-posed model is proportional to the area of tunneling transition. The\ncalculated value of tunneling conductivity is in qualitative agreement with\nexperimental data."
    },
    {
        "anchor": "Electronic Structure Trends of M\u00f6bius Graphene Nanoribbons from\n  Minimal-Cell Simulations: Investigating topological effects in materials requires often the modeling of\nmaterial systems as a whole. Such modeling restricts system sizes, and makes it\nhard to extract systematic trends. Here, we investigate the effect of M\\\"obius\ntopology in the electronic structures of armchair graphene nanoribbons. Using\ndensity-functional tight-binding method and minimum-cell simulations through\nrevised periodic boundary conditions, we extract electronic trends merely by\nchanging cells' symmetry operations and respective quantum number samplings. It\nturns out that for a minimum cell calculation, once geometric and magnetic\ncontributions are ignored, the effect of the global topology is unexpectedly\nshort-ranged.",
        "positive": "Ballistic-diffusive Phonon Heat Transport across Grain Boundaries: The propagation of a heat pulse in a single crystal and across grain\nboundaries (GBs) is simulated using a concurrent atomistic-continuum method\nfurnished with a coherent phonon pulse model. With a heat pulse constructed\nbased on a Bose-Einstein distribution of phonons, this work has reproduced the\nphenomenon of phonon focusing in single and polycrystalline materials.\nSimulation results provide visual evidence that the propagation of a heat pulse\nin crystalline solids with or without GBs is partially ballistic and partially\ndiffusive, i.e., there is a co-existence of ballistic and diffusive thermal\ntransport, with the long-wavelength phonons traveling ballistically while the\nshort-wavelength phonons scatter with each other and travel diffusively. To\ngain a quantitative understanding of GB thermal resistance, the kinetic energy\ntransmitted across GBs is monitored on the fly and the time-dependent energy\ntransmission for each specimen is measured; the contributions of coherent and\nincoherent phonon transport to the energy transmission are estimated.\nSimulation results reveal that the presence of GBs modifies the nature of\nthermal transport, with the coherent long-wavelength phonons dominating the\nheat conduction in materials with GBs. In addition, it is found the phonon-GB\ninteraction can result in the reconstruction of the GBs."
    },
    {
        "anchor": "Ground state cooling of mechanical resonators: We propose an application of a single Cooper pair box (Josephson qubit) for\nactive cooling of nanomechanical resonators. Latest experiments with Josephson\nqubits demonstrated that long coherence time of the order of microsecond can be\nachieved in special symmetry points. Here we show that this level of coherence\nis sufficient to perform an analog of the well known in quantum optics\n``laser'' cooling of a nanomechanical resonator capacitively coupled to the\nqubit. By applying an AC driving to the qubit or the resonator, resonators with\nfrequency of order 100 MHz and quality factors higher than $10^3$ can be\nefficiently cooled down to their ground state, while lower frequency resonators\ncan be cooled down to micro-Kelvin temperatures. We also consider an\nalternative setup where DC-voltage-induced Josephson oscillations play the role\nof the AC driving and show that cooling is possible in this case as well.",
        "positive": "Orbital magnetization and its effects in spin-chiral ferromagnetic\n  kagome lattice in the general spin-coupling region: The orbital magnetization and its effects on the two-dimensional kagom\\'{e}\nlattice with spin anisotropies included in the general Hund's coupling region\nhave been theoretically studied. The results show that the strength of the\nHund's coupling, as well as the spin chirality, contributes to the orbital\nmagnetization $\\mathcal{M}$. Upon varying both these parameters, it is found\nthat the two parts of $\\mathcal{M}$, i.e., the conventional part\n$\\mathbf{M}_{c}$ and the Berry-phase correction part $\\mathbf{M}_{\\Omega}$,\noppose each other. The anomalous Nernst conductivity is also calculated and a\npeak-valley structure as a function of the electron Fermi energy is obtained."
    },
    {
        "anchor": "Signature of pressure-induced topological phase transition in ZrTe$_5$: The layered van der Waals material ZrTe$_5$ is known as a candidate\ntopological insulator (TI), however its topological phase and the relation with\nother properties such as an apparent Dirac semimetallic state is still a\nsubject of debate. We employ a semiclassical multicarrier transport (MCT) model\nto analyze the magnetotransport of ZrTe$_5$ nanodevices at hydrostatic\npressures up to 2 GPa. The temperature dependence of the MCT results between 10\nand 300 K is assessed in the context of thermal activation, and we obtain the\npositions of conduction and valence band edges in the vicinity of the chemical\npotential. We find evidence of the closing and subsequent re-opening of the\nband gap with increasing pressure, which is consistent with a phase transition\nfrom weak to strong TI. This matches expectations from ab initio band structure\ncalculations, as well as previous observations that CVT-grown ZrTe$_5$ is in a\nweak TI phase in ambient conditions.",
        "positive": "Decoherence of the Superconducting Persistent Current Qubit: Decoherence of a solid state based qubit can be caused by coupling to\nmicroscopic degrees of freedom in the solid. We lay out a simple theory and use\nit to estimate decoherence for a recently proposed superconducting persistent\ncurrent design. All considered sources of decoherence are found to be quite\nweak, leading to a high quality factor for this qubit."
    },
    {
        "anchor": "Engineering Higher-Order Dirac and Weyl Semimetallic phase in 3D\n  Topolectrical Circuits: We propose a 3D topolectrical (TE) network that can be tuned to realize\nvarious higher-order topological gapless and chiral phases. We first study a\nhigher-order Dirac semimetal phase that exhibits a hinge-like Fermi arc linking\nthe Dirac points. This circuit can be extended to host highly tunable first-\nand second-order Weyl semimetal phases by introducing a non-reciprocal\nresistive coupling in the x-y plane that breaks time reversal symmetry. The\nfirst- and second-order Weyl points are connected by zero-admittance surface\nand hinge states, respectively. We also study the emergence of first- and\nsecond-order chiral modes induced by resistive couplings between similar nodes\nin the z-direction. These modes respectively occur in the midgap of the surface\nand hinge admittance bands in our circuit model without the need for any\nexternal magnetic field.",
        "positive": "Macrospin Tunneling and Magnetopolaritons with Nanomechanical\n  Interference: We theoretically address the quantum dynamics of a nanomechanical resonator\ncoupled to the macrospin of a magnetic nanoparticle by both instanton and\nperturbative approaches. We demonstrate suppression of the tunneling between\nopposite magnetizations by nanomechanical interference. By approximating the\nmacrospin as a two-level system, we describe magnetopolaritons and their\ndestruction by interference. The predictions can be verified experimentally by\na molecular magnet attached to a nanomechanical bridge."
    },
    {
        "anchor": "Generalized Triple-Component Fermions: Lattice Model, Fermi arcs, and\n  Anomalous Transport: We generalize the construction of time-reversal symmetry-breaking\ntriple-component semimetals, transforming under the pseudospin-1\nrepresentation, to arbitrary (anti-)monopole charge $2 n$, with $n=1,2,3$ in\nthe crystalline environment. The quasiparticle spectra of such systems are\ncomposed of two dispersing bands with pseudospin projections $m_s=\\pm 1$ and\nenergy dispersions $E_{\\bf k}=\\pm \\sqrt{ \\alpha^2_n k^{2n}_\\perp +v^2_z\nk^2_z}$, where $k_\\perp=\\sqrt{k^2_x+k^2_y}$, and one completely flat band at\nzero energy with $m_s=0$. We construct simple tight-binding models for such\nspin-1 excitations on a cubic lattice and address the symmetries of the\ngeneralized triple-component Hamiltonian. In accordance to the bulk-boundary\ncorrespondence, triple-component semimetals support $2 n$ branches of\ntopological Fermi arc surface states and also accommodate a \\emph{large}\nanomalous Hall conductivity (in the $xy$ plane), given by $\\sigma^{\\rm 3D}_{xy}\n\\propto 2 n \\times$ the separation of the triple-component nodes (in units of\n$e^2/h$). Furthermore, we compute the longitudinal magnetoconductivity, planar\nHall conductivity, and magneto thermal conductivity in these systems, which\nincrease as $B^2$ for sufficiently weak magnetic fields ($B$) due to the\nnontrivial Berry curvature in the medium. A generalization of our construction\nto arbitrary integer spin systems is also highlighted.",
        "positive": "Berry phase and the unconventional quantum Hall effect in graphene: The Berry phase of \\pi\\ in graphene is derived in a pedagogical way. The\nambiguity of how to calculate this value properly is clarified. Its connection\nwith the unconventional quantum Hall effect in graphene is discussed."
    },
    {
        "anchor": "Controlling the plasmonic properties of ultrathin TiN films at the\n  atomic level: By combining first principles theoretical calculations and experimental\noptical and structural characterization such as spectroscopic ellipsometry,\nX-ray spectroscopy, and electron microscopy, we study the dielectric\npermittivity and plasmonic properties of ultrathin TiN films at an atomistic\nlevel. Our results indicate a remarkably persistent metallic character of\nultrathin TiN films and a progressive red shift of the plasmon energy as the\nthickness of the film is reduced. The microscopic origin of this trend is\ninterpreted in terms of the characteristic two-band electronic structure of the\nsystem. Surface oxidation and substrate strain are also investigated to explain\nthe deviation of the optical properties from the ideal case. This paves the way\nto the realization of ultrathin TiN films with tailorable and tunable plasmonic\nproperties in the visible range for applications in ultrathin metasurfaces and\nflexible optoelectronic devices.",
        "positive": "Decoupled heat and charge rectification as a many-body effect in quantum\n  wires: We show that for a quantum wire with a local asymmetric scattering potential\nthe principal channels for charge and heat rectification decouple and\nrenormalise differently under electron interactions, with heat rectification\ngenerally being more relevant. The polarisation of the rectification results\nfrom quantum interference and is tuneable through external gating. Furthermore,\nfor spin polarised or helical electrons and sufficiently strong interactions a\nregime can be obtained in which heat transport is strongly rectified but charge\nrectification is very weak."
    },
    {
        "anchor": "Polarimetry of photon echo on charged and neutral excitons in\n  CdTe/(Cd,Mg)Te quantum wells: Coherent optical spectroscopy such as four-wave mixing and photon echo\ngeneration deliver detailed information on the energy levels involved in\noptical transitions through the analysis of polarization of the coherent\nresponse. In semiconductors, it can be applied to distinguish between different\nexciton complexes, which is a highly non-trivial problem in optical\nspectroscopy. We develop a simple approach based on photon echo polarimetry, in\nwhich polar plots of the photon echo amplitude are measured as function of the\nangle $\\varphi$ between the linear polarizations of the two exciting pulses.\nThe rosette-like polar plots reveal a distinct difference between the neutral\nand charged exciton (trion) optical transitions in semiconductor\nnanostructures. We demonstrate this experimentally by photon echo polarimetry\nof a 20-nm-thick CdTe/(Cd,Mg)Te quantum well at temperature of 1.5~K. Applying\nnarrow-band optical excitation we selectively excite different exciton\ncomplexes including the exciton, the trion, and the donor-bound exciton D$^0$X.\nWe find that polarimetry of the photon echo on the trion and D$^0$X is\nsubstantially different from the exciton: The echoes of the trion and D$^0$X\nare linearly polarized at the angle $2\\varphi$ with respect to the first pulse\npolarization and their amplitudes are weakly dependent on $\\varphi$. While on\nthe exciton the photon echo is co-polarized with the second exciting pulse and\nits amplitude scales as $\\cos\\varphi$.",
        "positive": "A Five Dimensional Generalization of the Topological Weyl Semimetal: We generalize the concept of three-dimensional topological Weyl semimetal to\na class of five dimensional (5D) gapless solids, where Weyl points are\ngeneralized to Weyl surfaces which are two-dimensional closed manifolds in the\nmomentum space. Each Weyl surface is characterized by a U(1) second Chern\nnumber $C_2$ defined on a four-dimensional manifold enclosing the Weyl surface,\nwhich is equal to its topological linking number with other Weyl surfaces in\n5D. In analogy to the Weyl semimetals, the surface states of the 5D metal take\nthe form of topologically protected Weyl fermion arcs, which connect the\nprojections of the bulk Weyl surfaces. The further generalization of\ntopological metal in $2n+1$ dimensions carrying the $n$-th Chern number $C_n$\nis also discussed."
    },
    {
        "anchor": "An Application of a Self-consistent Mean-Field Theoretical Model to\n  POPC-PSM-Cholesterol Bilayers: The connection between membrane inhomogeneity and the structural basis of\nlipid rafts has sparked interest in the lateral organization of model lipid\nbilayers of two and three components. In an effort to investigate anisotropic\nlipid distribution in mixed bilayers, a self-consistent mean-field theoretical\nmodel is applied to palmitoyloleoylphosphatidylcholine (POPC) - palmitoyl\nsphingomyelin (PSM) - Cholesterol mixtures. The compositional dependence of\nlateral organization in these mixtures is mapped onto a ternary plot. The model\nutilizes molecular dynamics simulations to estimate interaction parameters and\nto construct chain conformation libraries. We find that at some concentration\nratios the bilayers separate spatially into regions of higher and lower chain\norder coinciding with areas enriched with PSM and POPC respectively. To examine\nthe effect of the asymmetric chain structure of POPC on bilayer lateral\ninhomogeneity, we consider POPC-POPC interactions with and without angular\ndependence. Results are compared with experimental data and with results from a\nsimilar model for mixtures of dioleoylphosphatidylcholine (DOPC), steroyl\nsphingomyelin, and Cholesterol.",
        "positive": "Distinct Signatures For Coulomb Blockade and Aharonov-Bohm Interference\n  in Electronic Fabry-Perot Interferometers: Two distinct types of magnetoresistance oscillations are observed in two\nelectronic Fabry-Perot interferometers of different sizes in the integer\nquantum Hall regime. Measuring these oscillations as a function of magnetic\nfield and gate voltages, we observe three signatures that distinguish the two\ntypes. The oscillations observed in a 2.0 square micron device are understood\nto arise from the Coulomb blockade mechanism, and those observed in an 18\nsquare micron device from the Aharonov-Bohm mechanism. This work clarifies,\nprovides ways to distinguish, and demonstrates control over, these distinct\nphysical origins of resistance oscillations seen in electronic Fabry-Perot\ninterferometers."
    },
    {
        "anchor": "Electronic excitations of a single molecule contacted in a\n  three-terminal configuration: Low-temperature three-terminal transport measurements through a thiol\nend-capped Pi -conjugated molecule have been carried out. Electronic\nexcitations, including zero and finite-bias Kondo-effects have been observed\nand studied as a function of magnetic field. Using a simplified two-orbital\nmodel we have accounted for the spin and the electronic configuration of the\nfirst four charge states of the molecule. The charge-dependent couplings to\ngate, source and drain electrodes suggest a scenario in which charges and spins\nare localized at the ends of the molecule, close to the electrodes.",
        "positive": "Negative photoconductivity and hot-carrier bolometric detection of\n  terahertz radiation in graphene-phosphorene hybrid structures: We consider the effect of terahertz (THz) radiation on the conductivity of\nthe ungated and gated graphene (G)-phosphorene (P) hybrid structures and\npropose and evaluated the hot-carrier uncooled bolometric photodetectors based\non the GP-lateral diodes (GP-LDs) and GP-field-effect transistors (GP-FETs)\nwith the GP channel.\n  The operation of the GP-LDs and GP-FET photodetectors is associated with the\ncarrier heating by the incident radiation absorbed in the G-layer due to the\nintraband transitions. The carrier heating leads to the relocation of a\nsignificant fraction of the carriers into the P-layer. Due to a relatively low\nmobility of the carriers in the P-layer, their main role is associated with a\nsubstantial reinforcement of the scattering of the carriers. The GP-FET\nbolometric photodetector characteristics are effectively controlled by the gate\nvoltage. A strong negative conductivity of the GP-channel can provide much\nhigher responsivity of the THz hot-carriers GP-LD and GP-FET bolometric\nphotodetectors in comparison with the bolometers with solely the G-channels."
    },
    {
        "anchor": "Self-navigation of STM tip toward a micron sized sample: We demonstrate a simple capacitive based method to quickly and efficiently\nlocate micron size conductive samples on insulating substrates in a scanning\ntunneling microscope (STM). By using edge recognition the method is designed to\nlocate and identify small features when the STM tip is far above the surface\nallowing for crash-free search and navigation. The method can be implemented in\nany STM environment even at low temperatures and in strong magnetic field, with\nminimal or no hardware modifications.",
        "positive": "Non-Abelian states with negative flux: a new series of quantum Hall\n  states: By applying the idea of parafermionic clustering to composite bosons with\npositive as well as negative flux, a new series of trial wavefunctions to\ndescribe fractional quantum Hall states is proposed. These non-Abelian states\ncompete at filling factors k/(3k +/- 2) with other ground states like stripes\nor composite fermion states. These two series contain all the states recently\ndiscovered by Pan et al. [Phys. Rev. Lett. 90, 016801 (2003)] including the\neven denominator cases. Exact diagonalization studies on the sphere and torus\npoint to their possible relevance for filling factors 3/7, 3/11, and 3/8."
    },
    {
        "anchor": "Thickness and twist angle dependent interlayer excitons in metal\n  monochalcogenide heterostructures: Interlayer excitons, or bound electron-hole pairs whose constituent\nquasiparticles are located in distinct stacked semiconducting layers, are being\nintensively studied in heterobilayers of two dimensional semiconductors. They\nowe their existence to an intrinsic type-II band alignment between both layers\nthat convert these into p-n junctions. Here, we unveil a pronounced interlayer\nexciton (IX) in heterobilayers of metal monochalcogenides, namely gamma-InSe on\nepsilon-GaSe, whose pronounced emission is adjustable just by varying their\nthicknesses given their number of layers dependent direct bandgaps.\nTime-dependent photoluminescense spectroscopy unveils considerably longer\ninterlayer exciton lifetimes with respect to intralayer ones, thus confirming\ntheir nature. The linear Stark effect yields a bound electron-hole pair whose\nseparation d is just (3.6 \\pm 0.1) {\\AA} with d being very close to dSe = 3.4\n{\\AA} which is the calculated interfacial Se separation. The envelope of IX is\ntwist angle dependent and describable by superimposed emissions that are nearly\nequally spaced in energy, as if quantized due to localization induced by the\nsmall moir\\'e periodicity. These heterostacks are characterized by extremely\nflat interfacial valence bands making them prime candidates for the observation\nof magnetism or other correlated electronic phases upon carrier doping.",
        "positive": "Theory of Single Electron Spin Relaxation in Si/SiGe Lateral Coupled\n  Quantum Dots: We investigate the spin relaxation induced by acoustic phonons in the\npresence of spin-orbit interactions in single electron Si/SiGe lateral coupled\nquantum dots. The relaxation rates are computed numerically in single and\ndouble quantum dots, in in-plane and perpendicular magnetic fields. The\ndeformation potential of acoustic phonons is taken into account for both\ntransverse and longitudinal polarizations and their contributions to the total\nrelaxation rate are discussed with respect to the dilatation and shear\npotential constants. We find that in single dots the spin relaxation rate\nscales approximately with the seventh power of the magnetic field, in line with\na recent experiment. In double dots the relaxation rate is much more sensitive\nto the dot spectrum structure, as it is often dominated by a spin hot spot. The\nanisotropy of the spin-orbit interactions gives rise to easy passages, special\ndirections of the magnetic field for which the relaxation is strongly\nsuppressed. Quantitatively, the spin relaxation rates in Si are typically 2\norders of magnitude smaller than in GaAs due to the absence of the\npiezoelectric phonon potential and generally weaker spin-orbit interactions."
    },
    {
        "anchor": "Non-existence of spin-asymmetry of conductance in two-terminal devices: This paper is Comment to the Letter \"Oscillatory Spin-Filtering due to Gate\nControl of Spin-Dependent Interface Conductance\", by D. Grundler (PRL 86, 1058\n(2001)).",
        "positive": "Energy spectrum of valence band in HgTe quantum wells on the way from a\n  two to the three dimensional topological insulator: The magnetic field, temperature dependence and the Hall effect have been\nmeasured in order to determine the energy spectrum of the valence band in HgTe\nquantum wells with the width (20-200)nm. The comparison of hole densities\ndetermined from the period Shubnikov-de Haas oscillations and the Hall effect\nshows that states at the top of valence band are double degenerate in teh entry\nquantum wells width the width range. The cyclotron mass determined from\ntemperature dependence of SdH oscillations increases monotonically from\n(0.2-0.3) mass of the free electron, with increasing hole density from 2e11 to\n6e11 cm^-2. The determined dependence has been compared to theoretical one\ncalculate within the four band kp model. The experimental dependence was found\nto be strongly inconsistent with this predictions. It has been shown that the\ninclusion of additional factors (electric field, strain) does not remove the\ncontradiction between experiment and theory. Consequently it is doubtful that\nthe mentioned kp calculations adequately describe the valence band for any\nwidth of quantum well."
    },
    {
        "anchor": "Noise effects in the nonlinear thermoelectricity of a Josephson junction: We investigate the noise current in a thermally biased tunnel junction\nbetween two superconductors with different zero-temperature gaps. When the\nJosephson effect is suppressed, this structure can support a nonlinear\nthermoelectric effect due to the spontaneous breaking of electron-hole\nsymmetry, as we recently theoretically predicted. We discuss the possibly\nrelevant role played by the noise in the junction. While a moderate noise\ncontribution assists the generation of the thermoelectric signal, further\nunveiling the spontaneous nature of the electron-hole symmetry breaking, a\nlarge noise contribution can induce a switching between the two stationary\nthermoelectric values, thus hardening the detection of the effect and its\napplication. We demonstrate that the thermoelectric effect is robust to the\npresence of noise for a wide range of parameters and that the spurious\nfluctuations of the thermoelectric signal can be lowered by increasing the\ncapacitance of the junction, for instance by expanding the junction's size. Our\nresults pave the way to the future experimental observation of the\nthermoelectric effect in superconducting junctions, and to improved performance\nin quantum circuits designed for thermal management.",
        "positive": "Antiferromagnetic helix as an efficient spin polarizer: Interplay\n  between electric field and higher ordered hopping: We report spin filtration operation considering an antiferromagnetic helix\nsystem, possessing zero net magnetization. Common wisdom suggests that for such\na system, a spin-polarized current is no longer available from a beam of\nunpolarized electrons. But, once we apply an electric field perpendicular to\nthe helix axis, a large separation between up and down spin energy channels\ntakes place which yields a high degree of spin polarization. Such a\nprescription has not been reported so far to the best of our concern. Employing\na tight-binding framework to illustrate the antiferromagnetic helix, we compute\nspin filtration efficiency by determining spin selective currents using\nLandauer-B\\\"{u}ttiker formalism. Geometrical conformation plays an important\nrole in spin channel separation, and here we critically investigate the effects\nof short-range and long-range hoppings of electrons in presence of the electric\nfield. We find that the filtration performance gets improved with increasing\nthe range of hopping of electrons. Moreover, the phase of spin polarization can\nbe altered selectively by changing the strength and direction of the electric\nfield, and also by regulating the physical parameters that describe the\nantiferromagnetic helix. Finally, we explore the specific role of dephasing, to\nmake the system more realistic and to make the present communication a\nself-contained one. Our analysis may provide a new route of getting\nconformation-dependent spin polarization possessing longer range hopping of\nelectrons, and can be generalized further to different kinds of other\nfascinating antiferromagnetic systems."
    },
    {
        "anchor": "All-optical control of skyrmion configuration in CrI$_3$ monolayer: The potential for manipulating characteristics of skyrmions in a CrI$_3$\nmonolayer using circularly polarised light is explored. The effective\nskyrmion-light interaction is mediated by bright excitons whose magnetization\nis selectively influenced by the polarization of photons. The light-induced\nskyrmion dynamics is illustrated by the dependencies of the skyrmion size and\nthe skyrmion lifetime on the intensity and polarization of the incident light\npulse. Two-dimensional magnets hosting excitons thus represent a promising\nplatform for the control of topological magnetic structures by light.",
        "positive": "Interference oscillations of microwave photoresistance in double quantum\n  wells: We observe oscillatory magnetoresistance in double quantum wells under\nmicrowave irradiation. The results are explained in terms of the influence of\nsubband coupling on the frequency-dependent photoinduced part of the electron\ndistribution function. As a consequence, the magnetoresistance demonstrates the\ninterference of magneto-intersubband oscillations and conventional microwave-\ninduced resistance oscillations."
    },
    {
        "anchor": "Strain tuning the magnetic and transport properties of Mn$_3$Ge: The kagome lattice antiferromagnet Mn$_3$Ge has a local hexagonal symmetry\nwith a 120$^\\circ$ ordered ground state. This non-colinear ground state\nengenders a strong anomalous Hall response. The main goal of this work is to\nunderstand the effect of strain on this response. We derive an effective model\nfor the Hall vector which functions as our order parameter. Using this model we\nshow how both intra and inter planar strains can be used to switch the sign of\nthe Hall response at a constant magnetic field. Further, we also investigate\nthe effect of this strain on the spin wave band gaps and show that strain can\nbe used to effectively manipulate them, which can be used to tune the magnon\nresponses in this system.",
        "positive": "Non-Hermitian robust edge states in one-dimension: Anomalous\n  localization and eigenspace condensation at exceptional points: Capital to topological insulators, the bulk-boundary correspondence ties a\ntopological invariant computed from the bulk (extended) states with those at\nthe boundary, which are hence robust to disorder. Here we put forward an\nordering unique to non-Hermitian lattices, whereby a pristine system becomes\ndevoid of extended states, a property which turns out to be robust to disorder.\nThis is enabled by a peculiar type of non-Hermitian degeneracy where a\nmacroscopic fraction of the states coalesce at a single point with geometrical\nmultiplicity of $1$, that we call a phenomenal point."
    },
    {
        "anchor": "Curvatronics with bilayer graphene in an effective $4D$ spacetime: We show that in AB stacked bilayer graphene low energy excitations around the\nsemimetallic points are described by massless, four dimensional Dirac fermions.\nThere is an effective reconstruction of the 4 dimensional spacetime, including\nin particular the dimension perpendicular to the sheet, that arises dynamically\nfrom the physical graphene sheet and the interactions experienced by the\ncarriers. The effective spacetime is the Eisenhart-Duval lift of the dynamics\nexperienced by Galilei invariant L\\'evy-Leblond spin $\\frac{1}{2}$ particles\nnear the Dirac points. We find that changing the intrinsic curvature of the\nbilayer sheet induces a change in the energy level of the electronic bands,\nswitching from a conducting regime for negative curvature to an insulating one\nwhen curvature is positive. In particular, curving graphene bilayers allows\nopening or closing the energy gap between conduction and valence bands, a key\neffect for electronic devices. Thus using curvature as a tunable parameter\nopens the way for the beginning of curvatronics in bilayer graphene.",
        "positive": "Modeling of quantum electromechanical systems: We discuss methods for numerically solving the generalized Master equation\nGME which governs the time-evolution of the reduced density matrix of a\nmechanically movable mesoscopic device in a dissipative environment. As a\nspecific example, we consider the quantum shuttle -- a generic quantum\nnanoelectromechanical system (NEMS). When expressed in the oscillator basis,\nthe static limit of the GME becomes a large linear non-sparse matrix problem\n(characteristic size larger than 10^4 by 10^4) which however, as we show, can\nbe treated using the Arnoldi iteration scheme. The numerical results are\ninterpreted with the help of Wigner functions, and we compute the current and\nthe noise in a few representative cases."
    },
    {
        "anchor": "Andreev molecule in parallel InAs nanowires: Coupling individual atoms via tunneling fundamentally changes the state of\nmatter: electrons bound to atomic cores become delocalized resulting in a\nchange from an insulating to a metallic state, as it is well known from the\ncanonical example of solids. A chain of atoms could lead to more exotic states\nif the tunneling takes place via the superconducting vacuum and can induce\ntopologically protected excitations like Majorana or parafermions. Toward the\nrealization of such artificial chains, coupling a single atom to the\nsuperconducting vacuum is well studied, but the hybridization of two sites via\nthe superconductor was not yet reported. The peculiar vacuum of the BCS\ncondensate opens the way to annihilate or generate two electrons from the bulk\nresulting in a so-called Andreev molecular state. By employing parallel\nnanowires with an Al superconductor shell, two artificial atoms were created at\na minimal distance with an epitaxial superconducting link between.\nHybridization via the BCS vacuum was observed between the two artificial atoms\nfor the first time, as a demonstration of an Andreev molecular state.",
        "positive": "Excitation spectroscopy of few-electron states in artificial diatomic\n  molecules: We study the excitation spectroscopy of few-electron, parallel coupled double\nquantum dots (QDs). By applying a finite source drain voltage to a double QD\n(DQD), the first excited states observed in nonequilibrium charging diagrams\ncan be classified into two kinds in terms of the total effective electron\nnumber in the DQD, assuming a core filling. When there are an odd (even) number\nof electrons, one (two)-electron antibonding (triplet) state is observed as the\nfirst excited state. On the other hand, at a larger source drain voltage we\nobserve higher excited states, where additional single-particle excited levels\nare involved. Eventually, we identify the excited states with a calculation\nusing the Hubbard model and, in particular, we elucidate the quadruplet state,\nwhich is normally forbidden by the spin blockade caused by the selection rule."
    },
    {
        "anchor": "Resonant electron scattering by graphene antidot: The edge states which were observed on a linear edge of graphene may also\npersist on a curved edge. We calculate the elastic transport scattering cross\nsection on a graphene nanohole supporting the edge states. Resonant peaks in\nthe gate voltage dependence of conductivity of graphene with such nanoholes are\nobtained. Position and height of the resonances are determined by the\nlocalization depth of the quasibound edge states, and width -- by their\nlifetime. The scattering amplitude near the resonant energies has a strong\nvalley asymmetry. We evaluate the effect of moderate edge rippling,\ninhomogeneity of boundary parameter along the edge, and Coulomb effects\n(charged nanohole) on the edge states and show that they do not affect the\npresence of the resonances, but can substantially influence their position,\nheight and width. The local density of states near the nanohole also\ndemonstrates a resonant dependence on gate voltage.",
        "positive": "Incoherent magnetization dynamics in strain mediated switching of\n  magnetostrictive nanomagnets: Micromagnetic studies of the magnetization change in magnetostrictive\nnanomagnets subjected to stress are performed for nanomagnets of different\nsizes. The interplay between demagnetization, exchange and stress anisotropy\nenergies is used to explain the rich physics of size-dependent magnetization\ndynamics induced by modulating stress anisotropy in planar nanomagnets. These\nstudies have important implications for strain mediated ultralow energy\nmagnetization change in nanomagnets and its application in energy-efficient\nnanomagnetic computing systems."
    },
    {
        "anchor": "Enhanced quantum coherence in graphene caused by Pd cluster deposition: We report on the unexpected increase in the dephasing lengths of a graphene\nsheet caused by the deposition of Pd nanoclusters, as demonstrated by weak\nlocalization measurements. The dephasing lengths reached saturated values at\nlow temperatures. Theoretical calculations indicate the p-type charge transfer\nfrom the Pd clusters, which contributes more carriers. The saturated values of\ndephasing lengths often depend on both the carrier concentration and mean free\npath. Although some impurities are increased as revealed by decreased\nmobilities, the intense charge transfer leads to the improved saturated values\nand subsequent improved dephasing lengths.",
        "positive": "In-plane noncollinear exchange coupling mediated by helical edge states\n  in Quantum Spin Hall system: We study the Ruderman-Kittel-Kasuya-Yoshida (RKKY) interaction mediated by\nhelical edge states in quantum spin hall system. The helical edge states induce\nan in-plane noncollinear exchange coupling between two local spins, in contrast\nto the isotropic coupling induced in normal metal. The angle between the two\nlocal spins in the ground state depends on the Fermi level. This property may\nbe used to control the angle of spins by tuning the electric gate."
    },
    {
        "anchor": "Signatures of the excitonic memory effects in four-wave mixing processes\n  in cavity polaritons: We report the signatures of the exciton correlation effects with finite\nmemory time in frequency domain degenerate four-wave mixing (DFWM) in\nsemiconductor microcavity. By utilizing the polarization selection rules, we\ndiscriminate instantaneous, mean field interactions between excitons with the\nsame spins, long-living correlation due to the formation of biexciton state by\nexcitons with opposite spins, and short-memory correlation effects in the\ncontinuum of unbound two-exciton states. The DFWM spectra give us the relative\ncontributions of these effects and the upper limit for the time of the\nexciton-exciton correlation in the unbound two-exciton continuum. The obtained\nresults reveal the basis of the cavity polariton scattering model for the DFWM\nprocesses in high-Q GaAs microcavity.",
        "positive": "Polariton Induced Enhanced Emission from an Organic Dye under Strong\n  Coupling Regime: Exciton-polaritons in semiconductors are quasi-particles which have recently\nshown the capability to undergo phase transition into a coherent hybrid state\nof light and matter. The observation of such quasi-particles in organic\nmicrocavities has attracted increasing attention for their characteristic of\nreaching condensation at room temperature. In this work we demonstrate that the\nemission properties of organic polaritons do not depend on the overlap between\nthe absorption and emission states of the molecule and that the emission\ndynamics are modified in the strong coupling regime, showing a significant\nenhancement of the photoluminescence intensity as compared to the bare dye.\nThis paves the way to the investigation of molecules with large absorption\ncoefficients but poor emission efficiencies for the realization of polariton\ncondensates and organic electrically injected lasers by exploiting strong\nexciton-photon coupling regimes."
    },
    {
        "anchor": "Effect of Point Defects on the Optical and Transport Properties of MoS2\n  and WS2: Imperfections in the crystal structure, such as point defects, can strongly\nmodify the optical and transport properties of materials. Here, we study the\neffect of point defects on the optical and DC conductivities of single layers\nof semiconducting transition metal dichalcogenides with the form $M$S$_2$,\nwhere $M$=Mo or W. The electronic structure is considered within a six bands\ntight-binding model, which accounts for the relevant combination of $d$\norbitals of the metal $M$ and $p$ orbitals of the chalcogen $S$. We use the\nKubo formula for the calculation of the conductivity in samples with different\ndistributions of disorder. We find that $M$ and/or S defects create mid-gap\nstates that localize charge carriers around the defects and which modify the\noptical and transport properties of the material, in agreement with recent\nexperiments. Furthermore, our results indicate a much higher mobility for\n$p$-doped WS$_2$ in comparison to MoS$_2$.",
        "positive": "Inducing magnetism onto the surface of a topological crystalline\n  insulator: Inducing magnetism onto a topological crystalline insulator (TCI) has been\npredicted to result in several novel quantum electromagnetic effects. This is a\nconsequence of the highly strain-sensitive band topology of such\nsymmetry-protected systems. We thus show that placing the TCI surface of SnTe\nin proximity to EuS, a ferromagnetic insulator, induces magnetism at the\ninterface between SnTe and EuS and thus breaks time-reversal-symmetry in the\nTCI. Magnetotransport experiments on SnTe-EuS-SnTe trilayer devices reveal a\nhysteretic lowering of the resistance at the TCI surface that coincides with an\nincrease in the density of magnetic domain walls. This additional conduction\ncould be a signature of topologically-protected surface states within domain\nwalls. Additionally, a hysteretic anomalous Hall effect reveals that the usual\nin-plane magnetic moment of the EuS layer is canted towards a perpendicular\ndirection at the interface. These results are evidence of induced magnetism at\nthe SnTe-EuS interfaces resulting in broken time-reversal symmetry in the TCI."
    },
    {
        "anchor": "Semi-shunt field emission in electronic devices: We introduce a concept of semi-shunts representing needle shaped metallic\nprotrusions shorter than the distance between a device electrodes. Due to the\nlightening rod type of field enhancement, they induce strong electron emission.\nWe consider the corresponding signature effects in photovoltaic applications;\nthey are: low open circuit voltages and exponentially strong random device\nleakiness. Comparing the proposed theory with our data for CdTe based solar\ncells, we conclude that stress can stimulate semi-shunts' growth making them\nshunting failure precursors. In the meantime, controllable semi-shunts can play\na positive role mitigating the back field effects in photovoltaics.",
        "positive": "Transistor concepts based on lateral heterostructures of metallic and\n  semiconducting phases of MoS$_2$: In this paper we propose two transistor concepts based on lateral\nheterostructures of monolayer MoS$_2$, composed of adjacent regions of 1T\n(metallic) and 2H (semiconducting) phases, inspired by recent research showing\nthe possibility to obtain such heterostructures by electron beam irradiation.\nThe first concept, the lateral heterostructure field-effect transistor,\nexhibits potential of better performance with respect to the foreseen evolution\nof CMOS technology, both for high performance and low power applications.\nPerformance potential has been evaluated by means of detailed multi-scale\nmaterials and device simulations. The second concept, the planar barristor,\nalso exhibits potential competitive performance with CMOS, and an improvement\nof orders of magnitude in terms of the main figures of merit with respect to\nthe recently proposed vertical barristor."
    },
    {
        "anchor": "Theoretical realization of rich magnon topology by symmetry-breaking in\n  honeycomb bilayer ferromagnets: We reveal the rich magnon topology in honeycomb bilayer ferromagnets (HBF)\ninduced by the combined effect of interlayer exchange, Dzyaloshinskii-Moriya\ninteraction (DMI), and electrostatic doping (ED). In particular, we present a\nsystematic study of the Hamiltonian non-adiabatic evolution in the HBF\nparametric space, spanned by the symmetry-breaking terms (DMI and ED) and\ninterlayer exchange. We determine the band closure manifolds which are found to\ndivide the parametric space into six distinct regions, matched with five\ndistinct topological phases and one topologically trivial phase. The\ncharacteristic Chern numbers and thermal Hall conductivities are calculated for\nthe topological phases. Edge spectra, dictated by the bulk-edge correspondence,\nare also analyzed in the nanoribbon version of the model. Both bulk and edge\nspectra are found to be nonreciprocal as a consequence of ED and edge magnons\nare observed to counter propagate on opposite edges. The predicted results\noffer new insights on the manipulation of magnonic Chern numbers and magnon\ntopological transport via experimentally tunable parameters.",
        "positive": "Conditional Spontaneous Spin Polarization and Bifurcation Delay in\n  Coupled Two-Component Bose-Einstein Condensates: The spontaneous spin polarization and bifurcation delay in two-component\nBose-Einstein condensates coupled with Raman pulses are investigated. We find\nthat the bifurcation and the spontaneous spin polarization depend not only on\nthe system parameters, but also on the relative phase between two components.\nThrough bifurcations, the system enters into the spontaneous spin polarization\nregime from the Rabi regime. We also find that bifurcation delay appears when\nthe parameter is swept through the static bifurcation point. This bifurcation\ndelay is responsible for metastability leading to hysteresis. The area enclosed\nin the hysteresis loop increases with the sweeping rate of the parameter."
    },
    {
        "anchor": "Edge States of Bilayer Graphene in the Quantum Hall Regime: We study the low energy edge states of bilayer graphene in a strong\nperpendicular magnetic field. Several possible simple boundaries geometries\nrelated to zigzag edges are considered. Tight-binding calculations reveal three\ntypes of edge state behaviors: weakly, strongly, and non-dispersive edge\nstates. These three behaviors may all be understood within a continuum model,\nand related by non-linear transformations to the spectra of quantum Hall\nedge--states in a conventional two-dimensional electron system. In all cases,\nthe edge states closest to zero energy include a hole-like edge state of one\nvalley and a particle-like state of the other on the same edge, which may or\nmay not cross depending on the boundary condition. Edge states with the same\nspin generically have anticrossings that complicate the spectra, but which may\nbe understood within degenerate perturbation theory. The results demonstrate\nthat the number of edge states crossing the Fermi level in clean, undoped\nbilayer graphene depends BOTH on boundary conditions and the energies of the\nbulk states.",
        "positive": "Andreev Transport through Side-Coupled Double Quantum Dots: We study the transport through side-coupled double quantum dots, connected to\nnormal and superconducting (SC) leads with a T-shape configuration. We find,\nusing the numerical renormalization group, that the Coulomb interaction\nsuppresses SC interference in the side dot, and enhances the conductance\nsubstantially in the Kondo regime. This behavior stands in total contrast to a\nwide Kondo valley seen in the normal transport. The SC proximity penetrating\ninto the interfacial dot pushes the Kondo clouds, which screens the local\nmoment in the side dot, towards the normal lead to make the singlet bond long.\nThe conductance shows a peak of unitary limit as the cloud expands.\nFurthermore, two separate Fano structures appear in the gate-voltage dependence\nof the Andreev transport, where a single reduced plateau appears in the normal\ntransport."
    },
    {
        "anchor": "Sub-bandgap activated charges transfer in a graphene-MoS2-graphene\n  heterostructure: Monolayers of transition metal dichalcogenides are semiconducting materials\nwhich offer many prospects in optoelectronics. A monolayer of molybdenum\ndisulfide (MoS2) has a direct bandgap of 1.88 eV. Hence, when excited with\noptical photon energies below its bandgap, no photocarriers are generated and a\nmonolayer of MoS2 is not of much use in either photovoltaics or photodetection.\nHere, we demonstrate that large size MoS2 monolayer sandwiched between two\ngraphene layers makes this heterostructure optically active well below the band\ngap of MoS2. An ultrafast optical pump-THz probe experiment reveals in\nreal-time, transfer of carriers between graphene and MoS2 monolayer upon\nphotoexcitation with photon energies down to 0.5 eV. It also helps to unravel\nan unprecedented enhancement in the broadband transient THz response of this\ntri-layer material system. We propose possible mechanism which can account for\nthis phenomenon. Such specially designed heterostructures, which can be easily\nbuilt around different transition metal dichalcogenide monolayers, will\nconsiderably broaden the scope for modern optoelectronic applications at THz\nbandwidth.",
        "positive": "Single electron routing in a silicon quantum-dot array: The ability to transport single electrons on a quantum dot array dramatically\nincreases the freedom in designing quantum computation schemes that can be\nimplemented on solid-state devices. So far, however, routing schemes to\nprecisely control the transport paths of single electrons have yet to be\nestablished. Here, we propose a silicon single-electron router that transports\npumped electrons along the desired route on the branches of a T-shaped quantum\ndot array by inputting a synchronous phase-controlled signal to multiple gates.\nNotably, we show that it is possible to achieve a routing accuracy above 99% by\nimplementing assist gates in front of the branching paths. The results suggest\nnew possibilities for fast and accurate transport of single electrons on\nquantum dot arrays."
    },
    {
        "anchor": "Cohesion and Stability of Metal Nanowires: A Quantum Chaos Approach: A remarkably quantitative understanding of the electrical and mechanical\nproperties of metal wires with a thickness on the scale of a nanometer has been\nobtained within the free-electron model using semiclassical techniques.\nConvergent trace formulas for the density of states and cohesive force of a\nnarrow constriction in an electron gas, whose classical motion is either\nchaotic or integrable, are derived. Mode quantization in a metallic point\ncontact or nanowire leads to universal oscillations in its cohesive force,\nwhose amplitude depends only on a dimensionless quantum parameter describing\nthe crossover from chaotic to integrable motion, and is of order 1nN, in\nagreement with experiments on gold nanowires. A linear stability analysis shows\nthat the classical instability of a long wire under surface tension can be\ncompletely suppressed by quantum effects, leading to stable cylindrical\nconfigurations whose electrical conductance is a magic number 1, 3, 5, 6,...\ntimes the conductance quantum, in accord with recent results on alkali metal\nnanowires.",
        "positive": "Linear colossal magnetoresistance driven by magnetic textures in LaTiO3\n  thin films on SrTiO3: Linear magnetoresistance (LMR) is of particular interest for memory,\nelectronics, and sensing applications, especially when it does not saturate\nover a wide range of magnetic fields. One of its principal origins is local\nmobility or density inhomogeneities, often structural, which in the\nParish-Littlewood theory leads to an unsaturating LMR proportional to mobility.\nStructural disorder, however, also tends to limit the mobility and hence the\noverall LMR amplitude. An alternative route to achieve large LMR is via\nnon-structural inhomogeneities which do not affect the zero field mobility,\nlike magnetic domains. Here, linear positive magnetoresistance caused by\nmagnetic texture is reported in \\ch{LaTiO3}/\\ch{SrTiO3} heterostructures. The\nLMR amplitude reaches up to 6500\\% at 9T. This colossal value is understood by\nthe unusual combination of a very high thin film mobility, up to 40 000\ncm$^2$/V.s, and a very large coverage of low-mobility regions. These regions\ncorrelate with a striped magnetic structure, compatible with a spiral magnetic\ntexture in the \\ch{LaTiO3} film, revealed by low temperature Lorentz\ntransmission electron microscopy. These results provide a novel route for the\nengineering of large-LMR devices."
    },
    {
        "anchor": "Single Electron Quantum Dot in Two-Dimensional Transition Metal\n  Dichalcogenides: Spin-valley properties in two-dimensional (2D) semiconducting transition\nmetal dichalcogenides (TMDC) has attracted significant interest due to the\npossible applications in quantum computing. Spin-valley properties can be\nexploited in TMDC quantum dot (QD) with well-resolved energy levels. This\nrequires smaller QDs, especially in material systems with heavy carrier\neffective mass e.g. TMDCs and silicon. Device architectures employed for TMDC\nQDs so far have difficulty achieving smaller QDs. Therefore, an alternative\napproach in the device architecture is needed. Here, we propose a multilayer\ndevice architecture to achieve a gate-defined QD in TMDC with a relatively\nlarge energy splitting on the QD. We provide a range of device dimensions and\ndielectric thicknesses and its correlation with the QD energy splitting. The\ndevice architecture is modeled realistically. Moreover, we show that all the\ndevice parameters used in modeling are experimentally achievable. These studies\nlay the foundation for future work toward spin-valley qubits in TMDCs. The\nsuccessful implementation of these device architectures will drive the\ntechnological development of 2D materials-based quantum technologies.",
        "positive": "Observation of Robust Zero Energy Extended States: Topological edge states arise at the interface of two topologically-distinct\nstructures and have two distinct features: they are localized and robust\nagainst symmetry protecting disorder. On the other hand, conventional transport\nin one dimension is associated with extended states, which typically do not\nhave topological robustness. In this paper, using lossy coupled resonators in\none dimension, we demonstrate both theoretically and experimentally the\nexistence of robust states residing in the bulk. We show that they are\nunusually robust against disorders in coupling between adjacent sites and\nlosses. Our work paves the way to a new form of robust transport that is not\nlimited to boundary phenomena and can be accessed more easily from far field."
    },
    {
        "anchor": "Commensuration torques and lubricity in double moire systems: We study the commensuration torques and layer sliding energetics of\nalternating twist trilayer graphene (t3G) and twisted bilayer graphene on\nhexagonal boron nitride (t2G/BN) that have two superposed moire interfaces.\nLattice relaxations for typical graphene twist angles of $\\sim 1^{\\circ}$ in\nt3G or t2G/BN are found to break the out-of-plane layer mirror symmetry, give\nrise to layer rotation energy local minima dips of the order of $\\sim 10^{-1}$\nmeV/atom at double moire alignment angles, and have sliding energy landscape\nminima between top-bottom layers of comparable magnitude. Moire superlubricity\nis restored for twist angles as small as $\\sim 0.03^\\circ$ away from alignment\nresulting in suppression of sliding energies by several orders of magnitude of\ntypically $\\sim 10^{-4}$ meV/atom, hence indicating the precedence of rotation\nover sliding in the double moire commensuration process.",
        "positive": "Temperature induced phase averaging in one-dimensional mesoscopic\n  systems: We analyse phase averaging in one-dimensional interacting mesoscopic systems\nwith several barriers and show that for incommensurate positions an independent\naverage over several phases can be induced by finite temperature. For three\nstrong barriers with conductances G_i and mutual distances larger than the\nthermal length, we obtain G ~ sqrt{G_1 G_2 G_3} for the total conductance G.\nFor an interacting wire, this implies power laws in G(T) with novel exponents,\nwhich we propose as an experimental fingerprint to distinguish temperature\ninduced phase averaging from dephasing."
    },
    {
        "anchor": "Current Induced Hole Spin Polarization in Quantum Dot via Chiral Quasi\n  Bound State: We put forward a mechanism for current induced spin polarization for a hole\nin a quantum dot side-coupled to a quantum wire, that is based on the\nspin-orbit splitting of the valence band. We predict that in a stark contrast\nwith the traditional mechanisms based on the linear in momentum spin-orbit\ncoupling, an exponentially small bias applied to the quantum wire with heavy\nholes is enough to create the 100% spin polarization of a localized light hole.\nMicroscopically, the effect is related with the formation of chiral quasi bound\nstates and the spin dependent tunneling of holes from the quantum wire to the\nquantum dot. This novel current induced spin polarization mechanism is equally\nrelevant for the GaAs, Si and Ge based semiconductor nanostructures.",
        "positive": "Magnetization direction dependent spin Hall effect in 3d ferromagnets: We have studied the intrinsic spin Hall conductivity of 3d transition metal\nferromagnets using first-principles calculations. We find the spin Hall\nconductivity of bcc Fe and fcc Ni, prototypes of ferromagnetic systems, depends\non the direction of magnetization. The spin Hall conductivity of electrons with\ntheir spin orientation orthogonal to the magnetization are found to be larger\nthan that when the two are parallel. For example, the former can be more than\nfour times larger than the latter in bcc Fe. Such a difference arises due to\nthe anisotropy of the spin current operator in the spinor space: Its\nexpectation value with the Bloch states depends on the relative angle between\nthe conduction electron spin and the magnetization. A simple analytical form is\ndeveloped to describe the relation between the spinor states, with respect to\nthe magnetization direction, and the Berry and spin Berry curvatures. The model\ncan account for the characteristics found in the calculations. These results\nshow that ferromagnets can be used to generate spin current and its magnitude\ncan be controlled by the magnetization direction."
    },
    {
        "anchor": "Interferometry of Klein tunnelling electrons in graphene quantum rings: We theoretically study a current switch that exploits the phase acquired by a\ncharge carrier as it tunnels through a potential barrier in graphene. The\nsystem acts as an interferometer based on an armchair graphene quantum ring,\nwhere the phase difference between interfering electronic wave functions for\neach path can be controlled by tuning either the height or the width of a\npotential barrier in the ring arms. By varying the parameters of the potential\nbarriers the interference can become completely destructive. We demonstrate how\nthis interference effect can be used for developing a simple graphene-based\nlogic gate with high on/off ratio",
        "positive": "Devices with electrically tunable topological insulating phases: Solid-state topological insulating phases, characterized by spin-momentum\nlocked edge modes, provide a powerful route for spin and charge manipulation in\nelectronic devices. We propose to control charge and spin transport in the\nhelical edge modes by electrically switching the topological insulating phase\nin a HgTe/CdTe double quantum well device. We introduce the concept of a\ntopological field-effect-transistor and analyze possible applications to a spin\nbattery, which also realize a set up for an all-electrical investigation of the\nspin-polarization dynamics in metallic islands."
    },
    {
        "anchor": "Disentangling magnetic order on nanostructured surfaces: We present a synchrotron-based X-ray scattering technique which allows\ndisentangling magnetic properties of heterogeneous systems with nanopatterned\nsurfaces. This technique combines the nmrange spatial resolution of surface\nmorphology features provided by Grazing Incidence Small Angle X-ray Scattering\nand the high sensitivity of Nuclear Resonant Scattering to magnetic order. A\nsingle experiment thus allows attributing magnetic properties to structural\nfeatures of the sample; chemical and structural properties may be correlated\nanalogously. We demonstrate how this technique shows the correlation between\nstructural growth and evolution of magnetic properties for the case of a\nremarkable magnetization reversal in a structurally and magnetically\nnanopatterned sample system.",
        "positive": "Structural and magnetic investigation of the interfaces of\n  $\\mathrm{Fe_3O_4/MgO(001)}$ with and without NiO interlayer: We present an investigation on the structural and magnetic properties of the\ninterfaces of $\\mathrm{Fe_3O_4/MgO(001)}$ and $\\mathrm{Fe_3O_4/NiO/MgO(001)}$\nby extracting cation-selective magnetooptical depth profiles by means of x-ray\nmagnetic reflectivity (XRMR) in combination with charge-transfer multiplet\nsimulations of x-ray magnetic circular dichroism (XMCD) data. For\n$\\mathrm{Fe_3O_4/MgO(001)}$, the magnetooptical depth profiles at the\n$\\mathrm{Fe^{2+}_{oct}}$ and the $\\mathrm{Fe^{3+}_{oct}}$ resonant energies\nfollow exactly the structural profile, while the magnetooptical depth profile\nat the $\\mathrm{Fe^{3+}_{tet}}$ resonance is offset by $3.2\\pm1.3\\,$\\r{A} from\nthe interface, consistent with a B-site interface termination of\n$\\mathrm{Fe_3O_4}$ with fully intact magnetic order. In contrast, for\n$\\mathrm{Fe_3O_4/NiO(001)}$, the magnetooptical depth profiles at the\n$\\mathrm{Fe^{2+}_{oct}}$ and the $\\mathrm{Ni^{2+}}$ resonances agree with the\nstructural profile, but the interface positions of the magnetooptical depth\nprofiles at the $\\mathrm{Fe^{3+}_{oct}}$ and the $\\mathrm{Fe^{3+}_{tet}}$\nresonances are laterally shifted by $3.3\\pm 1.4\\,$\\r{A} and $2.7\\pm0.9\\,$\\r{A},\nrespectively, not consistent with a magnetically ordered stoichiometric\ninterface. This may be related to an intermixed $\\mathrm{(Ni,Fe)O}$ layer at\nthe interface. The magnetooptical depth profiles at the Ni $L_3$ edge reveal\nuncompensated magnetic moments throughout the NiO film."
    },
    {
        "anchor": "Quasi-particles in Fractional Quantum Hall Effect Edge Theories: We propose a quasi-particle formulation of effective edge theories for the\nfractional quantum Hall effect. For the edge of a Laughlin state with filling\nfraction \\nu=1/m, our fundamental quasi-particles are edge electrons of charge\n-e and edge quasi-holes of charge +e/m. These quasi-particles satisfy exclusion\nstatistics in the sense of Haldane. We exploit algebraic properties of edge\nelectrons to derive a kinetic equation for charge transport between a \\nu=1/m\nfractional quantum Hall edge and a normal metal. We also analyze alternative\n`Boltzmann' equations that are directly based on the exclusion statistics\nproperties of edge quasi-particles. Generalizations to more general filling\nfractions (Jain series) are briefly discussed.",
        "positive": "Andreev magnetotransport in low-dimensional proximity structures:\n  Spin-dependent conductance enhancement: We study the excess conductance due to the superconducting proximity effect\nin a ballistic two-dimensional electron system subject to an in-plane magnetic\nfield. We show that under certain conditions the interplay of the Zeeman spin\nsplitting and the effect of a screening supercurrent gives rise to a\nspin-selective Andreev enhancement of the conductance and anomalies in its\nvoltage, temperature and magnetic field characteristics. The magnetic-field\ninfluence on Andreev reflection is discussed in the context of using\nsuperconducting hybrid junctions for spin detection."
    },
    {
        "anchor": "Carbon chains and graphene nucleus synthesized on Ni(111) surface: Linear chains of about 10-13 carbon atoms were predicted to be the most\nfavorable phase on different metal surfaces prior to graphene nucleation.\nHowever, unlike the graphene that widely studied both theoretically and\nexperimentally, carbon chains on metal surfaces were not directly studied by\nSTM yet. Here we fill in the gap and report on STM experiments of linear carbon\nchains synthesized on Ni(111) through on-surface coupling of dehydrogenated\npropene molecules. Identification of chains was supported with DFT calculations\nand the proposed models consist of 12 carbon atoms, possibly covered by\nhydrogen atoms. Heating to 580 K leads to dramatic decrease of carbon chains\nand new phase appearance - graphene nucleus coexisted with nickel carbide.\nAfter flash annealing to 773 K (temperature of graphene synthesis), a small\nnumber of chains were presented on the Ni(111) surface, together with graphene\nislands and nickel carbide. The carbon chains are stable at room temperature\nand their mobility was directly observed by STM.",
        "positive": "Statistical analysis of spin switching in coupled spin-crossover\n  molecules: We study the switching behavior of two spin-crossover molecules residing in a\nnanojunction device consisting of two closely spaced gold electrodes. The spin\nstates are monitored through a real-time measurement of the resistance of the\njunction. A statistical analysis of the resistance values, the occupation\nprobabilities, and the lifetimes of the respective spin states shows that the\ntwo spin-crossover molecules are coupled to each other. We extract the\nparameters for a minimal model describing the two coupled spin-crossover\nmolecules. Finally, we use the time dependence of factorial cumulants to\ndemonstrate that the measured data indicates the presence of interactions\nbetween the two spin-crossover molecules."
    },
    {
        "anchor": "Organometallic Hexahapto Functionalization of Single Layer Graphene as a\n  Route to High Mobility Graphene Devices: Organometallic hexahapto chromium metal complexation of single layer\ngraphene, which involves constructive rehybridization of the graphene pi-system\nwith the vacant chromium d orbital, leads to field effect devices which retain\na high degree of the mobility with enhanced on-off ratio. This hexahapto mode\nof bonding between metal and graphene is quite distinct from the modification\nin electronic structure induced by conventional covalent sigma-bond formation\nwith creation of sp3 carbon centers in graphene lattice and this chemistry is\nreversible.",
        "positive": "Electronic Entanglement in the Vicinity of a Superconductor: A weakly biased normal-metal-superconductor junction is considered as a\npotential device injecting entangled pairs of quasi-particles into a\nnormal-metal lead. The two-particle states arise from Cooper pairs decaying\ninto the normal lead and are characterized by entangled spin- and orbital\ndegrees of freedom. The separation of the entangled quasi-particles is achieved\nwith a fork geometry and normal leads containing spin- or energy-selective\nfilters. Measuring the current-current cross-correlator between the two normal\nleads allows to probe the efficiency of the entanglement."
    },
    {
        "anchor": "Radio-frequency methods for Majorana-based quantum devices: fast charge\n  sensing and phase diagram mapping: Radio-frequency (RF) reflectometry is implemented in hybrid\nsemiconductor-superconductor nanowire systems designed to probe Majorana zero\nmodes. Two approaches are presented. In the first, hybrid nanowire-based\ndevices are part of a resonant circuit, allowing conductance to be measured as\na function of several gate voltages ~40 times faster than using conventional\nlow-frequency lock-in methods. In the second, nanowire devices are capacitively\ncoupled to a nearby RF single-electron transistor made from a separate\nnanowire, allowing RF detection of charge, including charge-only measurement of\nthe crossover from 2e inter-island charge transitions at zero magnetic field to\n1e transitions at axial magnetic fields above 0.6 T, where a topological state\nis expected. Single-electron sensing yields signal-to-noise exceeding 3 and\nvisibility 99.8% for a measurement time of 1 {\\mu}s.",
        "positive": "Influence of etching processes on electronic transport in mesoscopic\n  InAs/GaSb quantum well devices: We report the electronic characterization of mesoscopic Hall bar devices\nfabricated from coupled InAs/GaSb quantum wells sandwiched between AlSb\nbarriers, an emerging candidate for two-dimensional topological insulators. The\nelectronic width of the etched structures was determined from the low field\nmagneto-resistance peak, a characteristic signature of partially diffusive\nboundary scattering in the ballistic limit. In case of dry-etching the\nelectronic width was found to decrease with electron density. In contrast, for\nwet etched devices it stayed constant with density. Moreover, the boundary\nscattering was found to be more specular for wet-etched devices, which may be\nrelevant for studying topological edge states."
    },
    {
        "anchor": "Microwave heating effect on diamond sample of NV centers: Diamond samples of defects with negative charged nitrogen-vacancy (NV)\ncenters are promising solid state spin sensors suitable for quantum information\nprocessing, high sensitive measurements of magnetic, electric and thermal\nfields in nanoscale. The diamond defect with a NV center is unique for its\nrobust temperature-dependent zero field splitting Dgs of the triplet ground\nstate. This property enables optical readout of electron spin states through\nmanipulation of the ground triplet state using microwave resonance with Dgs\nfrom 100 K to about 600 K. Thus, prohibiting Dgs from unwanted external thermal\ndisturbances is crucial for an accurate measurement using diamond NV sensors.\nOur observation demonstrates the existence of a prominent microwave heating\neffect on the diamond samples of NV centers. The effect is inevitable to shift\nDgs and cause measurement errors. The temperature increment caused by the\neffect monotonically depends on the power and the duration of microwave\nirradiation. The effect is obvious with the microwave irradiation in the\ncontinuous mode and some pulse sequence modes, but is neglectable for the\nquantum lock-in XY8-N method.",
        "positive": "Current induced transition of anisotropic quantum Hall states: We compare the energies of the striped Hall state and the anisotropic charge\ndensity wave (ACDW) state at half-filled third and higher Landau levels in the\nsystem with injected currents. With no injected current, the ACDW state has a\nlower energy. We find that the striped Hall state becomes the lower energy\nstate when the injected current exceeds a critical value. The critical value is\nestimated as about 0.04-0.05 nA."
    },
    {
        "anchor": "Probing Non-Abelian Statistics in nu=12/5 Quantum Hall State: The tunneling current and shot noise of the current between two Fractional\nQuantum Hall (FQH) edges in the $ \\nu=12/5 $ FQH state in electronic\nMach-Zehnder interferometer are studied. It is shown that the tunneling current\nand shot noise can be used to probe the existence of $k=3 $ parafermion\nstatistics in the $ \\nu=12/5 $ FQH state. More specifically, the dependence of\nthe current on the Aharonov-Bohm flux in the Read-Rezayi state is asymmetric\nunder the change of the sign of the applied voltage. This property is absent in\nthe Abelian Laughlin states. Moreover the Fano factor can exceed 12.7 electron\ncharges in the $ \\nu=12/5 $ FQH state . This number well exceeds the maximum\npossible Fano factor in all Laughlin states and the $ \\nu=5/2 $ Moore-Read\nstate which was shown previously to be $ e $ and $ 3.2 e $ respectively.",
        "positive": "Rotating frame spin dynamics of a Nitrogen-Vacancy center in a diamond\n  nanocrystal: We investigate the spin dynamics of a Nitrogen-Vacancy (NV) center contained\nin an individual diamond nanocrystal in the presence of continuous microwave\nexcitation. Upon periodic reversal of the microwave phase, we observe a train\nof 'Solomon echoes' that effectively extends the system coherence lifetime to\nreach several tens of microseconds, depending on the microwave power and phase\ninversion rate. Starting from a model where the NV center interacts with a bath\nof paramagnetic defects on the nanocrystal surface, we use average Hamiltonian\ntheory to compute the signal envelope from its amplitude at the echo maxima.\nComparison between the effective Rabi and Solomon propagators shows that the\nobserved response can be understood as a form of higher-order decoupling from\nthe spin bath."
    },
    {
        "anchor": "Non-equilibrium transport at a dissipative quantum phase transition: We pioneerly investigate the non-equilibrium transport near a quantum phase\ntransition in a generic and relatively simple case model, the dissipative\nresonant level model, that has many ramifications in nanosystems. We formulate\na rigorous mapping and apply a controlled frequency-dependent renormalization\ngroup approach to compute the non-equilibrium current in the presence of a\nfinite bias voltage V. For V -> 0, we find that the conductance has its\nwell-known equilibrium form, while it displays a distinct non-equilibrium\nprofile at finite voltage.",
        "positive": "Nanoscale magnetic domains in polycrystalline Mn3Sn films imaged by a\n  scanning single-spin magnetometer: Noncollinear antiferromagnets with novel magnetic orders, vanishingly small\nnet magnetization and exotic spin related properties hold enormous promise for\ndeveloping next-generation, transformative spintronic applications. A major\nongoing research focus of this community is to explore, control, and harness\nunconventional magnetic phases of this emergent material system to deliver\nstate-of-the-art functionalities for modern microelectronics. Here we report\ndirect imaging of magnetic domains of polycrystalline Mn3Sn films, a\nprototypical noncollinear antiferromagnet, using nitrogen-vacancy-based\nsingle-spin scanning microscopy. Nanoscale evolution of local stray field\npatterns of Mn3Sn samples are systematically investigated in response to\nexternal driving forces, revealing the characteristic \"heterogeneous\" magnetic\nswitching behaviors in polycrystalline textured Mn3Sn films. Our results\ncontribute to a comprehensive understanding of inhomogeneous magnetic orders of\nnoncollinear antiferromagnets, highlighting the potential of nitrogen-vacancy\ncenters to study microscopic spin properties of a broad range of emergent\ncondensed matter systems."
    },
    {
        "anchor": "Low-energy electronic properties of Weyl semimetal quantum dot: It is necessary to study the properties of Weyl semimetal nanostructures for\npotential applications in nanoelectronics. Here we study the Weyl semimetal\nquantum dot with a most simple model Hamiltonian with only two Weyl points. We\nfocus on the low-energy electronic structure and show the correspondence to\nthat of three-dimensional Weyl semimetal, such as Weyl point and Fermi arc. We\nfind that there exist both surface and bulk states near Fermi level. The direct\ngap of bulk states reaches the minimum with the location determined by Weyl\npoint. There exists a quantum number with only several values supporting\nsurface states, which is the projection of Fermi arc. The property of surface\nstate is studied in detail, including circular persistent current, orbital\nmagnetic moment, and chiral spin polarization. Surface states will be broken by\na strong magnetic field and evolve into Landau levels gradually. Simple\nexpressions are derived to describe the energy spectra and electronic\nproperties of surface states both in the presence and absence of magnetic\nfield. In addition, this study may help design a method to verify Weyl\nsemimetal by separating out the signal of surface states since quantum dot has\nthe largest surface-to-volume ratio.",
        "positive": "Theory of fractional quantum Hall interferometers: Interference of fractionally charged quasi-particles is expected to lead to\nAharonov-Bohm oscillations with periods larger than the flux quantum. However,\naccording to the Byers-Yang theorem, observables of an electronic system are\ninvariant under an adiabatic insertion of a quantum of singular flux. We\nresolve this seeming paradox by considering a microscopic model of electronic\ninterferometers made from a quantum Hall liquid at filling factor 1/m. An\napproximate ground state of such interferometers is described by a Laughlin\ntype wave function, and low-energy excitations are incompressible deformations\nof this state. We construct a low-energy effective theory by restricting the\nmicroscopic Hamiltonian of electrons to the space of incompressible\ndeformations and show that the theory of the quantum Hall edge so obtained is a\ngeneralization of a chiral conformal field theory. In our theory, a\nquasi-particle tunneling operator is found to be a single-valued function of\ntunneling point coordinates, and its phase depends on the topology determined\nby the positions of Ohmic contacts. We describe strong coupling of the edge\nstates to Ohmic contacts and the resulting quasi-particle current through the\ninterferometer with the help of a master equation. We find that the coherent\ncontribution to the average quasi-particle current through Mach-Zehnder\ninterferometers does not vanish after summation over quasi-particle degrees of\nfreedom. However, it acquires oscillations with the electronic period, in\nagreement with the Byers-Yang theorem. Importantly, our theory does not rely on\nany ad-hoc constructions, such as Klein factors, etc. When the magnetic flux\nthrough an FP interferometer is varied with a modulation gate, current\noscillations have the quasi-particle periodicity, thus allowing for\nspectroscopy of quantum Hall edge states."
    },
    {
        "anchor": "Geometry-induced electron doping in periodic semiconductor\n  nanostructures: Recently, new quantum features have been observed and studied in the area of\nnanostructured layers. Nanograting on the surface of the thin layer imposes\nadditional boundary conditions on the electron wave function and induces\nG-doping or geometry doping. G-doping is equivalent to donor doping from the\npoint of view of the increase in electron concentration n. However, there are\nno ionized impurities. This preserves charge carrier scattering to the\nintrinsic semiconductor level and increases carrier mobility with respect to\nthe donor-doped layer. G-doping involves electron confinement to the\nnanograting layer. Here, we investigate the system of multiple nanograting\nlayers forming a series of hetero- or homojunctions. The system includes main\nand barrier layers. In the case of heterojunctions, both types of layers were\nG-doped. In the case of homojunctions, main layers were G-doped and barrier\nlayers were donor-doped. In such systems, the dependence of n on layer geometry\nand material parameters was analysed. Si and GaAs homojunctions and\nGaAs/AlGaAs, Si/SiGe, GaInP/AlGAs, and InP/InAlAs heterojunctions were studied.\nG-doping levels of 10^18-10^19 cm^-3 were obtained in homojunctions and type II\nheterojunctions. High G-doping levels were attained only when the difference\nbetween band gap values was low.",
        "positive": "Orientation dependence of the optical spectra in graphene at high\n  frequencies: On the basis of the Kubo formula we evaluated the optical conductivity of a\ngraphene sheet. The full behavior of frequency as well as temperature\ndependence of the optical conductivity is presented. We show that the\nanisotropy of conductivity can be significantly enhanced at high frequencies.\nThe photon absorption depends on the field polarization direction. At the\nfrequency comparable to the maximum separation of upper and lower bands the\nphoton-induced conduction of electrons is strongly suppressed if the\npolarization of field is along the zigzag direction. The corresponding optical\nconductivity is several orders of magnitude weaker than that when the light is\npolarizing along the armchair direction. We propose that the property of\norientation selection of absorption in the graphene can be used as a basis for\na high-frequency partial polarizer."
    },
    {
        "anchor": "Detecting Topological Currents in Graphene Superlattices: Topological materials may exhibit Hall-like currents flowing transversely to\nthe applied electric field even in the absence of a magnetic field. In graphene\nsuperlattices, which have broken inversion symmetry, topological currents\noriginating from graphene's two valleys are predicted to flow in opposite\ndirections and combine to produce long-range charge neutral flow. We observe\nthis effect as a nonlocal voltage at zero magnetic field in a narrow energy\nrange near Dirac points at distances as large as several microns away from the\nnominal current path. Locally, topological currents are comparable in strength\nto the applied current, indicating large valley-Hall angles. The long-range\ncharacter of topological currents and their transistor-like control by gate\nvoltage can be exploited for information processing based on the valley degrees\nof freedom.",
        "positive": "Graphene, plasmons and transformation optics: Here we study subwavelength gratings for coupling into graphene plasmons by\nmeans of an an- alytical model based on transformation optics that is not\nlimited to very shallow gratings. We consider gratings that consist of a\nperiodic modulation of the charge density in the graphene sheet, and gratings\nformed by this conductivity modulation together with a dielectric grating\nplaced in close vicinity of the graphene. Explicit expressions for the\ndispersion relation of the plasmon po- laritons supported by the system, and\nreflectance and transmittance under plane wave illumination are given. We\ndiscuss the conditions for maximising the coupling between incident radiation\nand plasmons in the graphene, finding the optimal modulation strength for a\nconductivity grating."
    },
    {
        "anchor": "Nanodevices and Maxwell's Demon: In the last twenty years there has been significant progress in our\nunderstanding of quantum transport far from equilibrium and a conceptual\nframework has emerged through a combination of the Landauer approach with the\nnon-equilibrium Green function (NEGF) method, which is now being widely used in\nthe analysis and design of nanoscale devices. It provides a unified description\nfor all kinds of devices from molecular conductors to carbon nanotubes to\nsilicon transistors covering different transport regimes from the ballistic to\nthe diffusive limit. In this talk I use a simple version of this model to\nanalyze a specially designed device that could be called an electronic\nMaxwell's demon, one that lets electrons go preferentially in one direction\nover another. My objective is to illustrate the fundamental role of contacts\nand demons in transport and energy conversion. The discussion is kept at an\nacademic level steering clear of real world details, but the illustrative\ndevices we use are very much within the capabilities of present-day technology.\nFor example, recent experiments on thermoelectric effects in molecular\nconductors agree well with the predictions from our model. The Maxwell's demon\ndevice itself is very similar to the pentalayer spin-torque device which has\nbeen studied by a number of groups though we are not aware of any discussion of\nthe possibility of using the device as a nanoscale heat engine or as a\nrefrigerator as proposed here. However, my objective is not to evaluate\npossible practical applications. Rather it is to introduce a simple transparent\nmodel showing how out-of-equibrium demons suitably incorporated into\nnanodevices can achieve energy conversion.",
        "positive": "Imaging Universal Conductance Fluctuations in Graphene: We study conductance fluctuations (CF) and the sensitivity of the conductance\nto the motion of a single scatterer in two-dimensional massless Dirac systems.\nOur extensive numerical study finds limits to the predicted universal value of\nCF. We find that CF are suppressed for ballistic systems near the Dirac point\nand approach the universal value at sufficiently strong disorder. The\nconductance of massless Dirac fermions is sensitive to the motion of a single\nscatterer. CF of order $e^2/h$ result from the motion of a single impurity by a\ndistance comparable to the Fermi wavelength. This result applies to graphene\nsystems with a broad range of impurity strength and concentration while the\ndependence on the Fermi wavelength can be explored {\\em via} gate voltages. Our\nprediction can be tested by comparing graphene samples with varying amounts of\ndisorder and can be used to understand interference effects in mesoscopic\ngraphene devices."
    },
    {
        "anchor": "Magnetoconductance of a two-dimensional metal in the presence of\n  spin-orbit coupling: We show that in the metallic phase of a two dimensional electron gas the\nspin-orbit coupling due to structure inversion asymmetry leads to a\ncharacteristic anisotropy in the magnetoconductance. Within the assumption that\nthe metallic phase can be described by a Fermi liquid, we compute the\nconductivity in the presence of an in-plane magnetic field. Both the spin-orbit\ncoupling and the Zeeman coupling with the magnetic field give rise to two spin\nsubbands, in terms of which most of the transport properties can be discussed.\n  The strongest conductivity anisotropy occurs for Zeeman energies of the order\nof the Fermi energy corresponding to the depopulation of the upper spin\nsubband. The energy scale associated with the spin-orbit coupling controls the\nstrength of the effect. More in particular, we find that the detailed behavior\nand the sign of the anisotropy depends on the underlying scattering mechanism.\nAssuming small angle scattering to be the dominant scattering mechanism our\nresults agree with recent measurement on Si-MOSFET's in the vicinity of the\nmetal-insulator transition.",
        "positive": "Fractionalization noise in edge channels of integer quantum Hall states: A theoretical calculation is presented of current noise which is due charge\nfractionalization, in two interacting edge channels in the integer quantum Hall\nstate at filling factor $\\nu=2$. Because of the capacitive coupling between the\nchannels, a tunneling event, in which an electron is transferred from a biased\nsource lead to one of the two channels, generates propagating plasma mode\nexcitations which carry fractional charges on the other edge channel. When\nthese excitations impinge on a quantum point contact, they induce low-frequency\ncurrent fluctuations with no net average current. A perturbative treatment in\nthe weak tunneling regime yields analytical integral expressions for the noise\nas a function of the bias on the source. Asymptotic expressions of the noise in\nthe limits of high and low bias are found."
    },
    {
        "anchor": "Deep learning of deformation-dependent conductance in thin films:\n  nanobubbles in graphene: Motivated by the ever-improving performance of deep learning techniques, we\ndesign a mixed input convolutional neural network approach to predict transport\nproperties in deformed nanoscale materials using a height map of deformations\n(from scanning probe information) as input. We employ our approach to study\nelectrical transport in a graphene nanoribbon deformed by a number of randomly\npositioned nano-bubbles. Our network is able to make conductance predictions\nvalid to an average error of 4.3\\%. We demonstrate that such low average errors\nare achieved by including additional inputs like energy in a highly redundant\nfashion, which allows predictions that are 30-40\\% more accurate than\nconventional architectures. We demonstrate that the same method can learn to\npredict the valley-resolved conductance, with success specifically in\nidentifying the energy at which inter-valley scattering becomes prominent. We\ndemonstrate the robustness of the approach by testing the pre-trained network\non samples with deformations differing in number and shape from the training\ndata. We employ a graph theoretical analysis of the structure and outputs of\nthe network and conclude that a tight-binding Hamiltonian is effectively\nencoded in the first layer of the network. We confirm our graph theoretical\nanalysis numerically for different hopping processes in a trained network and\nfind the result to be accurate within an error of 1\\%. Our approach contributes\na new theoretical understanding and a refined methodology to the application of\ndeep learning for the determination transport properties based on real-space\ndisorder information.",
        "positive": "Proximity-induced low-energy renormalization in hybrid\n  semiconductor-superconductor Majorana structures: A minimal model for the hybrid superconductor-semiconductor nanowire Majorana\nplatform is developed that fully captures the effects of the low-energy\nrenormalization of the nanowire modes arising from the presence of the parent\nsuperconductor. In this model, the parent superconductor is an active component\nthat participates explicitly in the low-energy physics, not just a passive\npartner that only provides proximity-induced Cooper pairs for the nanowire.\nThis treatment on an equal footing of the superconductor and the semiconductor\nhas become necessary in view of recent experiments, which do not allow a\nconsistent interpretation based just on the bare semiconductor properties. The\ngeneral theory involves the evaluation of the exact semiconductor Green\nfunction that includes a dynamical self-energy correction arising from the\ntunnel-coupled superconductor. General conditions for the emergence of\ntopological superconductivity are worked out for single-band as well as\nmulti-band nanowires and detailed numerical results are given for both infinite\nand finite wire cases. The topological quantum phase diagrams are provided\nnumerically and the Majorana bound states are obtained along with their\noscillatory energy splitting behaviors due to wavefunction overlap in finite\nwires. Renormalization effects are shown to be both qualitatively and\nquantitatively important in modifying the low-energy spectrum of the nanowire.\nThe results of the theory are found to be in good qualitative agreement with\nMajorana nanowire experiments, leading to the conclusion that the\nproximity-induced low-energy renormalization of the nanowire modes by the\nparent superconductor is of fundamental importance in\nsuperconductor-semiconductor hybrid structures. Implications of the general\ntheory for obtaining true zero energy topological Majorana modes are pointed\nout."
    },
    {
        "anchor": "Topology optimization of simultaneous photonic and phononic bandgaps and\n  highly effective phoxonic cavity: By using the non-dominated sorting-based genetic algorithm II, we study the\ntopology optimization of the two-dimensional phoxonic crystals (PxCs) with\nsimultaneously maximal and complete photonic and phononic bandgaps. Our results\nshow that the optimized structures are composed of the solid lumps with narrow\nconnections, and their Pareto-optimal solution set can keep a balance between\nphotonic and phononic bandgap widths. Moreover, we investigate the localized\nstates of PxCs based on the optimized structure and obtain structures with more\neffectively multimodal photon and phonon localization. The presented structures\nwith highly focused energy are good choices for the PxC sensors. For practical\napplication, we design a simple structure with smooth edges based on the\noptimized structure. It is shown that the designed simple structure has the\nsimilar properties with the optimized structure, i.e. simultaneous wide\nphononic and photonic bandgaps and a highly effective phononic/photonic cavity,\nsee Figures 8(b) and 8(c).",
        "positive": "Suppression of Spin Dephasing in a Two-Dimensional Electron Gas with a\n  Quantum Point Contact: Spin-orbit coupling is a source of strong spin dephasing in two- and\nthree-dimensional semiconducting systems. We report that spin dephasing in a\ntwo-dimensional electron gas can be suppressed by introducing a quantum point\ncontact. Surprisingly, this suppression was not limited to the vicinity of the\ncontact but extended to the entire two-dimensional electron gas. This\nfacilitates the electrical control of the spin degree of freedom in a\ntwo-dimensional electron gas through spin-orbit coupling."
    },
    {
        "anchor": "Silver Nanowires on Carbon Nanotube Aerogel Sheets for Flexible,\n  Transparent Electrodes: Flexible, free-standing transparent conducting electrodes (TCEs) with\nsimultaneously tunable transmittances up to 98% and sheet resistances down to\n11 {\\Omega}/sq were prepared by a facile spray-coating method of silver\nnanowires (AgNWs) onto dry-spun multiwall carbon nanotube (MWNT) aerogels.\nCounterintuitively, the transmittance of the hybrid electrodes can be increased\nas the mass density of AgNWs within the MWNT aerogels increase, however, the\nfinal achievable transmittance depends on the initial transparency of the MWNT\naerogels. At the same time, a strong decrease in sheet resistance is obtained\nwhen AgNWs form a percolated network along the MWNT aerogel. Additionally,\nanisotropic reduction in sheet resistance and polarized transmittance of\nAgNWs/MWNTs aerogel is achieved with this method. The final AgNWs/MWNTs hybrid\nTCEs transmittance and sheet resistance can be fine-tuned by spray-coating\nmechanisms or by the choice of initial MWNT aerogel density. Thus, a wide range\nof AgNWs/MWNTs hybrid TCEs with optimized optoelectronic properties can be\nachieved depending of the requirements needed. Finally, the free-standing\nAgNWs/MWNTs hybrid TCEs can be laminated onto a wide range of substrates\nwithout the need of a bonding aid.",
        "positive": "Controlled Skyrmion Ratchet in Linear Protrusion Defects: Using atomistic simulations, we investigate the dynamical behavior of a\nsingle skyrmion interacting with an asymmetric linear protrusion array under\nexternal ac driving. When the ac drive is applied along the $x$ direction, the\nskyrmion moves along the hard direction of the substrate asymmetry in three\nphases: a pinned phase with localized skyrmion orbits, a constant velocity\nphase where the orbits become delocalized, and a reentrant pinned phase with\nlarger localized orbits. We measure the dependence of the skyrmion velocity on\nthe frequency and amplitude of the ac drive. All three phases appear for all\nfrequency values, and in the constant velocity phase the skyrmion velocity\ndepends only on the frequency and not on the amplitude of the ac drive. When ac\ndriving is applied in the $y$ direction, the skyrmion moves along the easy\ndirection of the substrate asymmetry and exhibits the same three phases as for\n$x$ direction driving along with a fourth phase which, at high driving\nfrequencies, consists of a series of constant velocity phases, each with\ndifferent average skyrmion velocities. For low frequencies, the constant\nvelocity phase is lost and the skyrmion speed increases linearly with\nincreasing ac drive amplitude due to a Magnus boost effect. Our findings\nsuggest new ways to create reliable data transport for spintronic devices using\nskyrmions as information carriers, where the skyrmion direction and speed can\nbe controlled by varying only the ac drive amplitude and frequency."
    },
    {
        "anchor": "Controlling Sub-nm Gaps in Plasmonic Dimers using Graphene: Graphene is used as the thinnest possible spacer between gold nanoparticles\nand a gold substrate. This creates a robust, repeatable, and stable\nsub-nanometre gap for massive plasmonic field enhancements. White light\nspectroscopy of single 80 nm gold nanoparticles reveals plasmonic coupling\nbetween the particle and its image within the gold substrate. While for a\nsingle graphene layer, spectral doublets from coupled dimer modes are observed\nshifted into the near infra-red, these disappear for increasing numbers of\nlayers. These doublets arise from plasmonic charge transfer, allowing the\ndirect optical measurement of out-of-plane conductivity in such layered\nsystems. Gating the graphene can thus directly produce plasmon tuning.",
        "positive": "Observing the Nonequilibrium Dynamics of the Quantum Transverse-Field\n  Ising Chain in Circuit QED: We show how a quantum Ising spin chain in a time-dependent transverse\nmagnetic field can be simulated and experimentally probed in the framework of\ncircuit QED with current technology. The proposed setup provides a new platform\nfor observing the nonequilibrium dynamics of interacting many-body systems. We\ncalculate its spectrum to offer a guideline for its initial experimental\ncharacterization. We demonstrate that quench dynamics and the propagation of\nlocalized excitations can be observed with the proposed setup and discuss\nfurther possible applications and modifications of this circuit QED quantum\nsimulator."
    },
    {
        "anchor": "$Z_2$ index for gapless fermionic modes in the vortex core of three\n  dimensional paired Dirac fermions: We consider the gapless modes along the vortex line of the fully gapped,\nmomentum independent paired states of three-dimensional Dirac fermions. For\nthis, we require the solution of fermion zero modes of the corresponding\ntwo-dimensional problem in the presence of a point vortex, in the plane\nperpendicular to the vortex line. Based on the spectral symmetry requirement\nfor the existence of the zero mode, we identify the appropriate generalized\nJackiw-Rossi Hamiltonians for different paired states. A four-dimensional\ngeneralized Jackiw-Rossi Hamiltonian possesses spectral symmetry with respect\nto an antiunitary operator, and gives rise to a single zero mode only for the\n{\\em odd vorticity}, which is formally described by a $Z_2$ index. In the\npresence of generic perturbations such as chemical potential, Dirac mass, and\nZeeman couplings, the associated two-dimensional problem for the odd parity\ntopological superconducting state maps onto {\\em two} copies of generalized\nJackiw-Rossi Hamiltonian, and consequently an odd vortex binds two Majorana\nfermions. In contrast, there are no zero energy states for the topologically\ntrivial $s$-wave superconductor in the presence of any chiral symmetry breaking\nperturbation in the particle-hole channel, such as regular Dirac mass. We show\nthat the number of one-dimensional dispersive modes along the vortex line is\nalso determined by the index of the associated two-dimensional problem. For an\naxial superfluid state in the presence of various perturbations, we discuss the\nconsequences of the $Z_2$ index on the anomaly equations.",
        "positive": "Exact dynamics of dissipative electronic systems and quantum transport:\n  Hierarchical equations of motion approach: A quantum dissipation theory is formulated in terms of hierarchically coupled\nequations of motion for an arbitrary electronic system coupled with grand\ncanonical Fermion bath ensembles. The theoretical construction starts with the\nsecond--quantization influence functional in path integral formalism, in which\nthe Fermion creation and annihilation operators are represented by Grassmann\nvariables. Time--derivatives on influence functionals are then performed in a\nhierarchical manner, on the basis of calculus--on--path--integral algorithm.\nBoth the multiple--frequency--dispersion and the non-Markovian reservoir\nparametrization schemes are considered for the desired hierarchy construction.\nThe resulting formalism is in principle exact, applicable to interacting\nsystems, with arbitrary time-dependent external fields. It renders an exact\ntool to evaluate various transient and stationary quantum transport properties\nof many-electron systems. At the second--tier truncation level the present\ntheory recovers the real--time diagrammatic formalism developed by Sch\\\"{o}n\nand coworkers. For a single-particle system, the hierarchical formalism\nterminates at the second tier exactly, and the Landuer--B\\\"{u}ttiker's\ntransport current expression is readily recovered."
    },
    {
        "anchor": "X-ray holography of skyrmionic cocoons in aperiodic magnetic multilayers: The development and characterization of three-dimensional (3D) topological\nmagnetic textures has become an important topic in modern magnetism both for\nfundamental and technological perspectives. Among the novel 3D spin textures,\nskyrmionic cocoons have been successfully stabilized in magnetic multilayers\nhaving a variable thickness of the ferromagnet in the vertical direction of the\nstack. These ellipsoidal 3D magnetic textures remain vertically confined in a\nfraction of the total thickness while coexisting with fully columnar skyrmions.\nHere, we use X-ray holography with about 15 nm lateral resolution to\ninvestigate how their properties depend on the field and temperature. We\nobserve circular objects with different amplitude of contrast which evidences\nthe presence of different 3D objects located in various vertical parts of the\nmultilayer. Moreover, we witness during out-of-plane cycling an attractive\ninteraction between cocoons located at various heights, mainly due to the stray\nfield, which impacts their horizontal positioning. The X-ray holography\nmeasurements also allow to determine the size of the cocoons at remanence\nwhich, at room temperature, possess diameter close to 100 nm in average.\nCombining this transmission technique with magnetic force microscopy and\nmicromagnetic simulations gives a precise insight into the 3D distribution of\nthe magnetization which demonstrate the 3D nature of skyrmionic cocoons.",
        "positive": "Polynomial method for canonical calculations: A practical version of the polynomial canonical formalism is developed for\nnormal mesoscopic systems consisting of N independent electrons. Drastic\nsimplification of calculations is attained by means of proper ordering excited\nstates of the system. In consequence the exact canonical partition function can\nbe represented as a series in which the first term corresponds to the ground\nstate whereas successive groups of terms belong to many particle-hole\nexcitations (one particle-hole two particle-hole and so on). At small\ntemperatures (T<10 inter-level spacings near the Fermi level) the number of\nterms which should be taken into account is weakly dependent on N and remains\n<10 even if N~100000. The elaborated method makes canonical calculations to be\nnot more complicated than the grand canonical ones and is free from any\nlimitations on N and T."
    },
    {
        "anchor": "Handwritten Digit Recognition by Spin Waves in a Skyrmion Reservoir: By performing numerical simulations for the handwritten digit recognition\ntask, we demonstrate that a magnetic skyrmion lattice confined in a thin-plate\nmagnet possesses high capability of reservoir computing. We obtain a high\nrecognition rate of more than 88%, higher by about 10% than a baseline taken as\nthe echo state network model. We find that this excellent performance arises\nfrom enhanced nonlinearity in the transformation which maps the input data onto\nan information space with higher dimensions, carried by interferences of spin\nwaves in the skyrmion lattice. Because the skyrmions require only application\nof static magnetic field instead of nanofabrication for their creation in\ncontrast to other spintronics reservoirs, our result consolidates the high\npotential of skyrmions for application to reservoir computing devices.",
        "positive": "Scanning Gate Spectroscopy on Nanoclusters: A gated probe for scanning tunnelling microscopy (STM) has been developed.\nThe probe extends normal STM operations by means of an additional electrode\nfabricated next to the tunnelling tip. The extra electrode does not make\ncontact with the sample and can be used as a gate. We report on the recipe used\nfor fabricating the tunnelling tip and the gate electrode on a silicon nitride\ncantilever. We demonstrate the functioning of the scanning gate probes by\nperforming single-electron tunnelling spectroscopy on 20-nm gold clusters for\ndifferent gate voltages."
    },
    {
        "anchor": "Period halving of Persistent Currents in Mesoscopic Mobius ladders: We investigate the period halving of persistent currents(PCs) of\nnon-interacting electrons in isolated mesoscopic M\\\"{o}bius ladders without\ndisorder, pierced by Aharonov-Bhom flux. The mechanisms of the period halving\neffect depend on the parity of the number of electrons as well as on the\ninterchain hopping. Although the data of PCs in mesoscopic systems are\nsample-specific, some simple rules are found in the canonical ensemble average,\nsuch as all the odd harmonics of the PCs disappear, and the signals of even\nharmonics are non-negative. {PACS number(s): 73.23.Ra, 73.23.-b, 68.65.-k}",
        "positive": "Electric field induced strong enhancement of electroluminescence in\n  multi-Layer MoS2: The layered transition metal dichalcogenides (TMDs) have attracted\nconsiderable interest due to their unique electronic and optical properties.\nHere we report electric field induced strong electroluminescence in multi-layer\nMoS2 and WSe2. We show that GaN-Al2O3-MoS2 and GaN-Al2O3-MoS2-Al2O3-graphene\nvertical heterojunctions can be created with excellent rectification behaviour.\nElectroluminescence studies demonstrate prominent direct bandgap excitonic\nemission in multi-layer MoS2 over the entire vertical junction area.\nImportantly, the electroluminescence efficiency observed in multi-layer MoS2 is\ncomparable to or even higher than that in monolayers, corresponding to a\nrelative electroluminescence enhancement factor of >1000 in multi-layer MoS2\nwhen compared to its photoluminescence. This striking enhancement of\nelectroluminescence can be attributed to the high electric field induced\ncarrier redistribution from low energy points (indirect bandgap) to high energy\npoints (direct bandgap) of k-space, arising from the unique band structure of\nMoS2 with a much higher density of states at high energy points. The electric\nfield induced electroluminescence is general for other TMDs including WSe2, and\ncan provide a fundamental platform to probe the carrier injection, population\nand recombination in multi-layer TMDs and open up a new pathway toward TMD\nbased optoelectronic devices."
    },
    {
        "anchor": "Thermoelectric effects in correlated quantum dots and molecules: We investigate thermoelectric properties of correlated quantum dots and\nmolecules, described by a single level Anderson model coupled to conduction\nelectron leads, by using Wilson's numerical renormalization group method. In\nthe Kondo regime, the thermopower, $S(T)$, exhibits two sign changes, at\ntemperatures $T=T_{1}$ and $T=T_{2}>T_{1}$. We find that $T_{2}$ is of order\nthe level width $\\Gamma$ and $T_{1}> T_{p}\\approx T_{K}$, where $T_{p}$ is the\nposition of the Kondo induced peak in the thermopower and $T_{K}$ is the Kondo\nscale. No sign change is found outside the Kondo regime, or, for weak\ncorrelations, making a sign change in $S(T)$ a particularly sensitive signature\nof strong correlations and Kondo physics. For molecules, we investigate the\neffect of screening by conduction electrons on the thermoelectric transport. We\nfind that a large screening interaction enhances the figure of merit in the\nKondo and mixed valence regimes.",
        "positive": "Defect-Correlated Skyrmions and Controllable Generation in\n  Perpendicularly Magnetized CoFeB Ultrathin Films: Skyrmions have attracted significant interest due to their topological spin\nstructures and fascinating physical features. The skyrmion phase arises in\nmaterials with Dzyaloshinskii-Moriya (DM) interaction at interfaces or in\nvolume of non-centrosymmetric materials. However, although skyrmions were\ngenerated experimentally, one critical intrinsic relationship between\nfabrication, microstructures, magnetization and the existence of skyrmions\nremains to be established. Here, two series of CoFeB ultrathin films with\ncontrolled atomic scale structures are employed to reveal this relationship. By\ninverting the growth order, the amount of defects can be artificially tuned,\nand skyrmions are shown to be preferentially formed at defect sites. The stable\nregion and the density of the skyrmions can be efficiently controlled in the\nreturn magnetization loops by utilizing first-order reversal curves to reach\nvarious metastable states. These findings establish the general and intrinsic\nrelationship from sample preparation to skyrmion generation, offering an\nuniversal method to control skyrmion density."
    },
    {
        "anchor": "The Role of Percolation and Sheet Dynamics during Heat Conduction in\n  poly-dispersed Graphene Nanofluids: A thermal transport mechanism leading to the enhanced thermal conductivity of\nGraphene nanofluids has been proposed. The Graphene sheet size is postulated to\nbe the key to the underlying mechanism. Based on a critical sheet size derived\nfrom Stokes-Einstein equation for the poly-dispersed nanofluid, sheet\npercolation and Brownian motion assisted sheet collisions are used to explain\nthe heat conduction. A collision dependant dynamic conductivity considering\nDebye approximated volumetric specific heat due to phonon transport in Graphene\nhas been incorporated. The model has been found to be in good agreement with\nexperimental data.",
        "positive": "Long-Range Dipole-Dipole Interaction and Anomalous F\u00f6rster Energy\n  Transfer across Hyperbolic Meta Material: We study radiative energy transfer between a donor-acceptor pair across a\nhyperbolic metamaterial slab. We show that similar to a perfect lens a\nhyperbolic lens allows for giant energy transfer rates. For a realistic\nrealization of a hyperbolic multilayer metamaterial we find an enhancement of\nup to three orders of magnitude with respect to the transfer rates across a\nplasmonic silver film of the same size especially for frequencies which\ncoincide with the epsilon-near zero and the epsilonnear pole frequencies.\nFurthermore, we compare exact results based on the S-matrix method with results\nobtained from effective medium theory. Our finding of very large dipole-dipole\ninteraction at distances of the order of a wavelength has important\nconsequences for producing radiative heat transfer, quantum entanglement etc."
    },
    {
        "anchor": "Spin Current Generation and Detection in the Presence of AC Gate: We predict that in a narrow gap III-V semiconductor quantum well or a wire an\nobservable spin current can be generated with a time dependent gate to modify\nthe Rashba spin-orbit coupling constant. Methods to rectify the so generated AC\ncurrent are discussed. An all-electric method of spin current detection is\nsuggested, which measures the voltage on the gate in the vicinity of a 2D\nelectron gas carrying a time dependent spin current. Both the generation and\ndetection do not involve any optical or magnetic mediators.",
        "positive": "Exciton-phonon coupling efficiency in CdSe quantum dots embedded in ZnSe\n  nanowires: Exciton luminescence of a CdSe quantum dot (QD) inserted in a ZnSe nanowire\nis strongly influenced by the dark exciton states. Because of the small size of\nthese QDs (2-5nm), exchange interaction between hole and electron is highly\nenhanced and we measured large energy splitting between bright and dark exciton\nstates ($\\Delta E\\in [4, 9.2 ]$ meV) and large spin flip rates between these\nstates. Statistics on many QDs showed that this splitting depends on the QD\nsize. Moreover, we measured an increase of the spin flip rate to the dark\nstates with increasing energy splitting. We explain this observation with a\nmodel taking into account the fact that the exciton-phonon interaction depends\non the bright to dark exciton energy splitting as well as on the size and shape\nof the exciton wave function. It also has consequences on the exciton line\nintensity at high temperature."
    },
    {
        "anchor": "Composite Dirac fermions in graphene: Generalizing the notion of composite fermions to the \"pseudo-relativistic\"\nQuantum Hall phenomena in graphene, we discuss a possible emergence of\ncompressible states at the filling factors -3/2, -1/2, 1/2, 3/2. This analysis\nis further extended to the nearby incompressible states viewed as the Integer\nQuantum Hall Effect of the composite Dirac fermions, as well as those that\nmight occur at the filling factors -1, 0, 1 as a result of the\n(pseudo)spin-singlet pairing between them.",
        "positive": "Phase diagram and edge states of the $\u03bd=5/2$ fractional quantum Hall\n  state with Landau level mixing and finite well thickness: The $\\nu=5/2$ fractional quantum Hall effect is a system of intense\nexperimental and theoretical interest as its ground state may host non-abelian\nexcitations, but the exact nature of the ground state is still undetermined. We\npresent the results of an exact diagonalization study of an electron system in\nthe disk configuration including the effects of Landau level (LL) mixing and\nthe finite thickness of the quantum well confining the electrons. The\ndegeneracy between the two leading candidates for the ground state, the\nPfaffian and anti-Pfaffian, is broken by interactions with a neutralizing\nbackground, in addition to the inclusion of two- and three-body interactions\nvia LL mixing. As a result of the neutralizing background in the disc\nconfiguration, there is a phase transition from the anti-Pfaffian to the\nPfaffian as LL mixing is turned on, in stark contrast to what is observed in a\nspherical geometry. The LL mixing leads to an increased charge $e/4$ quasihole\nsize. LL mixing interactions are also shown to overcome the effects of edge\nreconstruction. Due to finite thickness effects, these properties are enhanced\ndramatically. We also find that only the Pfaffian and anti-Pfaffian states\ncontinue to possess energy gaps at finite width, while gaps for compressible\nstripe states close."
    },
    {
        "anchor": "Valley-related multiple Hall effect in single-layer VSi2P4: 2D materials with valley-related multiple Hall effect are both fundamentally\nintriguing and practically appealing to explore novel phenomena and\napplications, but have been largely overlooked up to date. Here, using\nfirst-principles calculations, we present that valley related multiple Hall\neffect can exist in single-layer VSi2P4. We identify single-layer VSi2P4 as a\nferromagnetic semiconductor with out-of-plane magnetization and valley physics.\nArising from the joint effect of inversion symmetry breaking and time reversal\nsymmetry breaking, the exotic spontaneous valley polarization occurs in\nsingle-layer VSi2P4, thus facilitating the observation of anomalous valley Hall\neffect. Moreover, under external strain, band inversion can occur at only one\nof the valleys of single-layer VSi2P4, enabling the long-sought\nvalley-polarized quantum anomalous Hall effect, and meanwhile the anomalous\nvalley Hall effect is well preserved.. Our work not only enriches the research\non valley-related multiple Hall effect, but also opens a new avenue for\nexploring valley-polarized quantum anomalous Hall effect.",
        "positive": "Charge Number Dependence of the Dephasing Rates of a Graphene Double\n  Quantum Dot in a Circuit QED Architecture: We use an on-chip superconducting resonator as a sensitive meter to probe the\nproperties of graphene double quantum dots at microwave frequencies.\nSpecifically, we investigate the charge dephasing rates in a circuit quantum\nelectrodynamics architecture. The dephasing rates strongly depend on the number\nof charges in the dots, and the variation has a period of four charges, over an\nextended range of charge numbers. Although the exact mechanism of this fourfold\nperiodicity in dephasing rates is an open problem, our observations hint at the\nfourfold degeneracy expected in graphene from its spin and valley degrees of\nfreedom."
    },
    {
        "anchor": "Distinguishing impurity concentrations in GaAs and AlGaAs, using very\n  shallow undoped heterostructures: We demonstrate a method of making a very shallow, gateable, undoped\n2-dimensional electron gas. We have developed a method of making very low\nresistivity contacts to these structures and systematically studied the\nevolution of the mobility as a function of the depth of the 2DEG (from 300nm to\n30nm). We demonstrate a way of extracting quantitative information about the\nbackground impurity concentration in GaAs and AlGaAs, the interface roughness\nand the charge in the surface states from the data. This information is very\nuseful from the perspective of molecular beam epitaxy (MBE) growth. It is\ndifficult to fabricate such shallow high-mobility 2DEGs using modulation doping\ndue to the need to have a large enough spacer layer to reduce scattering and\nswitching noise from remote ionsied dopants.",
        "positive": "Magnons in a Quasicrystal: Propagation, Localization and Extinction of\n  Spin Waves in Fibonacci Structures: Magnonic quasicrystals exceed the possibilities of spin wave (SW)\nmanipulation offered by regular magnonic crystals, because of their more\ncomplex SW spectra with fractal characteristics. Here, we report the direct\nx-ray microscopic observation of propagating SWs in a magnonic quasicrystal,\nconsisting of dipolarly coupled permalloy nanowires arranged in a\none-dimensional Fibonacci sequence. SWs from the first and second band as well\nas evanescent waves from the band gap between them are imaged. Moreover,\nadditional mini-band gaps in the spectrum are demonstrated, directly indicating\nan influence of the quasiperiodicity of the system. The experimental results\nare interpreted using numerical calculations and we deduce a simple model to\nestimate the frequency position of the magnonic gaps in quasiperiodic\nstructures. The demonstrated features of SW spectra in one-dimensional magnonic\nquasicrystals allows utilizing this class of metamaterials for magnonics and\nmakes them an ideal basis for future applications."
    },
    {
        "anchor": "Transient stimulated emission from multi-split-gated graphene structure: Mechanism of transient population inversion in graphene with multi-splitted\n(interdigitated) top-gate and grounded back gate is suggested and examined for\nthe mid-infrared (mid-IR) spectral region. Efficient stimulated emission after\nfast lateral spreading of carriers due to drift-diffusion processes is found\nfor the case of a slow electron-hole recombination in the passive region. We\nshow that with the large gate-to-graphene distance the drift process always\nprecedes the diffusion process, due to the ineffective screening of the inplane\nelectric field by the gates. Conditions for lasing with a gain above 100\ncm$^{-1}$ are found for cases of single- and multi-layer graphene placed in the\nwaveguide formed by the top and back gates. Both the waveguide losses and\ntemperature effects are analyzed.",
        "positive": "Experimental verification of PbBi$_{2}$Te$_{4}$ as a 3D topological\n  insulator: The first experimental evidence is presented of the topological insulator\nstate in PbBi$_{2}$Te$_{4}$. A single surface Dirac cone is observed by\nangle-resolved photoemission spectroscopy (ARPES) with synchrotron radiation.\nTopological invariants $\\mathbb{Z}_2$ are calculated from the {\\it ab initio}\nband structure to be 1; (111). The observed two-dimensional iso-energy contours\nin the bulk energy gap are found to be the largest among the known\nthree-dimensional topological insulators. This opens a pathway to achieving a\nsufficiently large spin current density in future spintronic devices."
    },
    {
        "anchor": "Electrical detectability of magnon-mediated spin current shot noise: A magnonic spin current crossing a ferromagnet-metal interface is accompanied\nby spin current shot noise arising from the discrete quanta of spin carried by\nmagnons. In thin films, e.g., the spin of so-called squeezed magnons have been\nshown to deviate from the common value $\\hbar$, with corresponding changes in\nthe spin noise. In experiments, spin currents are typically converted to charge\ncurrents via the inverse spin Hall effect. We here analyze the magnitude of the\nspin current shot noise in the charge channel for a typical electrically\ndetected spin pumping experiment, and find that the voltage noise originating\nfrom the spin current shot noise is much smaller than the inevitable\nJohnson-Nyquist noise. Furthermore, we find that due to the local nature of the\nspin-charge conversion, the ratio of spin current shot noise and\nJohnson-Nyquist noise cannot be systematically enhanced by tuning the sample\ngeometry, in contrast to the linear increase in dc spin pumping voltage with\nsample length. Instead, the ratio depends sensitively on material-specific\ntransport properties. Our analysis thus provides guidance for the experimental\ndetection of squeezed magnons through spin pumping shot noise.",
        "positive": "Persistent current in one-dimensional non-superconducting mesoscopic\n  rings: effects of single hopping impurity, in-plane electric field and\n  foreign atoms: Persistent current in one-dimensional non-superconducting mesoscopic rings\nthreaded by a slowly varying magnetic flux $\\phi$ is studied based on the\ntight-binding model. The behavior of the persistent current is discussed in\nthree aspects: (a) single hopping impurity, (b) in-plane electric field and (c)\nin presence of some foreign atoms."
    },
    {
        "anchor": "Spin-anisotropic magnetic impurity in a Fermi gas: poor man's scaling\n  equation integration: We consider a single magnetic impurity described by the spin--anisotropic\ns-d(f) exchange (Kondo) model and formulate scaling equation for the\nspin-anisotropic model when the density of states (DOS) of electrons is a power\nlaw function of energy (measured relative to the Fermi energy). We solve this\nequation containing terms up to the second order in coupling constants in terms\nof elliptic functions. From the obtained solution we find the phases\ncorresponding to the infinite isotropic antiferromagnetic Heisenberg exchange,\nto the impurity spin decoupled from the electron environment (only for the\npseudogap DOS), and to the infinite Ising exchange (only for the diverging\nDOS). We analyze the critical surfaces, corresponding to the finite isotropic\nantiferromagnetic Heisenberg exchange for the pseudogap DOS.",
        "positive": "Non-Hermitian delocalization in a 2D photonic quasicrystal: Quasicrystals show long-range order, but lack translational symmetry. So far,\ntheoretical and experimental studies suggest that both Hermitian and\nnon-Hermitian quasicrystals show localized eigenstates. This localization is\ndue to the fractal structure of the spectrum in the Hermitian case and to the\ntransition to diffusive bands via exceptional points in the non-Hermitian case.\nHere, we present an experimental study of a dodecagonal (12-fold) photonic\nquasicrystal based on electromagnetically-induced transparency in a Rb vapor\ncell. The transition to a quasicrystal is obtained by superposing two honeycomb\nlattices at 30$^\\circ$ with a continuous tuning of their amplitudes.\nNon-Hermiticity is controlled independently. We study the spatial expansion of\na probe wavepacket. In the Hermitian case, the wavepacket expansion is\nsuppressed when the amplitude of the second lattice is increased (quasicrystal\nlocalization). We find a new regime, where increasing the non-Hermitian\npotential in the quasicrystal enhances spatial expansion, with the $C_{12}$\nsymmetry becoming visible in the wavepacket structure. This real-space\nexpansion is due to a k-space localization on specific quasicrystal modes. Our\nresults show that the non-Hermitian quasicrystal behavior is richer than\npreviously thought. The localization properties of the quasicrystals can be\nused for beam tailoring in photonics, but are also important in other fields."
    },
    {
        "anchor": "Pre-selectable integer quantum conductance of electrochemically\n  fabricated silver point contacts: The controlled fabrication of well-ordered atomic-scale metallic contacts is\nof great interest: it is expected that the experimentally observed high\npercentage of point contacts with a conductance at non-integer multiples of the\nconductance quantum G_0 = 2e^2/h in simple metals is correlated to defects\nresulting from the fabrication process. Here we demonstrate a combined\nelectrochemical deposition and annealing method which allows the controlled\nfabrication of point contacts with pre-selectable integer quantum conductance.\nThe resulting conductance measurements on silver point contacts are compared\nwith tight-binding-like conductance calculations of modeled idealized junction\ngeometries between two silver crystals with a predefined number of contact\natoms.",
        "positive": "Detection of the anomalous velocity with sub-picosecond time resolution\n  in semiconductor nanostructures: We report on the time-resolved detection of the anomalous velocity,\nconstituting charge carriers moving perpendicular to an electric driving field,\nin undoped GaAs quantum wells. For this we optically excite the quantum wells\nwith circularly polarized femtosecond laser pulses, thereby creating a state\nwhich breaks time-inversion symmetry. We then employ a quasi single cycle\nterahertz pulse as electric driving field to induce the anomalous velocity. The\nelectromagnetic radiation emitted from the anomalous velocity is studied with a\nsub-picosecond time resolution and reveals intriguing results. We are able to\ndistinguish between intrinsic (linked to the Berry curvature) and extrinsic\n(linked to scattering) contributions to the anomalous velocity both originating\nfrom the valence band and observe local energy space dependence of the\nanomalous velocity. Our results thus constitute a significant step towards\nnon-invasive probing of the anomalous velocity locally in the full\nenergy/momentum space and enable the investigation of many popular physical\neffects such as anomalous Hall effect and spin Hall effect on ultrafast time\nscales."
    },
    {
        "anchor": "Characterizing wave functions in graphene nanodevices: electronic\n  transport through ultrashort graphene constrictions on a boron nitride\n  substrate: We present electronic transport measurements through short and narrow (30x30\nnm) single layer graphene constrictions on a hexagonal boron nitride substrate.\nWhile the general observation of Coulomb-blockade is compatible with earlier\nwork, the details are not: we show that the area on which charge is localized\ncan be significantly larger than the area of the constriction, suggesting that\nthe localized states responsible for Coulomb-blockade leak out into the\ngraphene bulk. The high bulk mobility of graphene on hexagonal boron nitride,\nhowever, seems not consistent with the short bulk localization length required\nto see Coulomb-blockade. To explain these findings, charge must instead be\nprimarily localized along the imperfect edges of the devices and extend along\nthe edge outside of the constriction. In order to better understand the\nmechanisms, we compare the experimental findings with tight-binding simulations\nof such constrictions with disordered edges. Finally we discuss previous\nexperiments in the light of these new findings.",
        "positive": "Experimental evidence of low-lying gapped excitations in the quantum\n  fluid at nu=5/2: The low-lying neutral excitation spectrum of the incompressible quantum Hall\nfluid at $\\nu=5/2$ is investigated by inelastic light scattering. Gapped modes\nare observable only in a very narrow filling factor range centered at 5/2 at\nenergies that overlap estimates from transport activation gaps. The modes are\ninterpreted as critical points in the wave-vector dispersion of excitations\nthat preserve spin orientation. For very small changes $|\\delta\\nu|\\lesssim\n0.01$ the gapped modes disappear and a continuum of low-lying excitations takes\nover indicating the transition from an incompressible fluid at 5/2 to a\ncompressible state. Observations of spin wave modes indicate spin polarization\nof the 5/2 and 2+1/3 quantum Hall fluids."
    },
    {
        "anchor": "Topological classification of shot noise on fractional quantum Hall\n  edges: Electrical and thermal transport on a fractional quantum Hall edge are\ndetermined by topological quantities inherited from the corresponding bulk\nstate. While electrical transport is the standard method for studying edges,\nthermal transport appears more challenging. Here, we show that the shot noise\ngenerated on the edge provides a fully electrical method to probe the edge\nstructure. In the incoherent regime, the noise falls into three topologically\ndistinct universality classes: charge transport is always ballistic while\nthermal transport is either ballistic, diffusive, or \"antiballistic\".\nCorrespondingly, the noise either vanishes, decays algebraically or is constant\nup to exponentially small corrections in the edge length.",
        "positive": "Bandgap engineering of zigzag graphene nanoribbons by manipulating edge\n  states via defective boundaries: One of severe limits of graphene nanoribbons (GNRs) in future applications is\nthat zigzag GNRs (ZGNRs) are gapless, so cannot be used in field effect\ntransistors (FETs). In this paper, using tight-binding approach and first\nprinciples method, we derived and proved a general edge (boundary) condition\nfor the opening of a significant bandgap in ZGNRs with defective edge\nstructures. The proposed semiconducting GNRs have some interesting properties\nincluding the one that they can be embedded and integrated in a large piece of\ngraphene without the need of completely cutting them out. We also demonstrated\na new type of high-performance all-ZGNR FET."
    },
    {
        "anchor": "Weak antilocalization effect of high-mobility two-dimensional electron\n  gas in inversion layer on p-type HgCdTe: Magnetoconductance of a gated two-dimensional electron gas (2DEG) in the\ninversion layer on p-type HgCdTe crystal is investigated. At strong magnetic\nfields, characteristic features such as quantum Hall effect of a 2DEG with\nsingle subband occupation are observed. At weak magnetic fields, weak\nantilocalization effect in ballistic regime is observed. Phase coherence time\nand zero-field spin-splitting are extracted according to Golub's model. The\ntemperature dependence of dephasing rate is consistent with Nyquist mechanism\nincluding both singlet and triplet channel interactions.",
        "positive": "The Quantum Hall Effect: Unified Scaling Theory and Quasi-particles at\n  the Edge: We address two fundamental issues in the physics of the quantum Hall effect:\na unified description of scaling behavior of conductances in the integral and\nfractional regimes, and a quasi-particle formulation of the chiral Luttinger\nLiquids that describe the dynamics of edge excitations in the fractional\nregime."
    },
    {
        "anchor": "Efficient anchor loss suppression in coupled near-field optomechanical\n  resonators: Elastic dissipation through radiation towards the substrate is a major loss\nchannel in micro- and nanomechanical resonators. Engineering the coupling of\nthese resonators with optical cavities further complicates and constrains the\ndesign of low-loss optomechanical devices. In this work we rely on the coherent\ncancellation of mechanical radiation to demonstrate material and surface\nabsorption limited silicon near-field optomechanical resonators oscillating at\ntens of MHz. The effectiveness of our dissipation suppression scheme is\ninvestigated at room and cryogenic temperatures. While at room temperature we\ncan reach a maximum quality factor of 7.61k ($fQ$-product of the order of\n$10^{11}$~Hz), at 22~K the quality factor increases to 37k, resulting in a\n$fQ$-product of $2\\times10^{12}$~Hz.",
        "positive": "Effective Dynamics of 2D Bloch Electrons in External Fields Derived From\n  Symmetry: We develop a comprehensive theory for the effective dynamics of Bloch\nelectrons based on symmetry. We begin with a scheme to systematically derive\nthe irreducible representations (IRs) characterizing the Bloch functions.\nStarting from a tight-binding (TB) approach, we decompose the TB basis\nfunctions into localized symmetry-adapted atomic orbitals and crystal-periodic\nsymmetry-adapted plane waves. Each of these subproblems is independent of the\ndetails of a particular crystal structure and it is largely independent of the\nother subproblem, hence permitting for each subproblem an independent universal\nsolution. Taking monolayer MoS$_2$ and few-layer graphene as examples, we\ntabulate the symmetrized $p$ and $d$ orbitals as well as the symmetrized plane\nwave spinors for these systems. The symmetry-adapted basis functions\nblock-diagonalize the TB Hamiltonian such that each block yields eigenstates\ntransforming according to one of the IRs of the group of the wave vector $G_k$.\nFor many crystal structures, it is possible to define multiple distinct\ncoordinate systems such that for wave vectors $k$ at the border of the\nBrillouin zone the IRs characterizing the Bloch states depend on the coordinate\nsystem, i.e., these IRs of $G_k$ are not uniquely determined by the symmetry of\na crystal structure. The different coordinate systems are related by a\ncoordinate shift that results in a rearrangement of the IRs of $G_k$\ncharacterizing the Bloch states. We illustrate this rearrangement with three\ncoordinate systems for MoS$_2$ and tri-layer graphene. Using monolayer MoS$_2$\nas an example, we combine the symmetry analysis of its bulk Bloch states with\nthe theory of invariants to construct a generic multiband Hamiltonian for\nelectrons near the $K$ point of the Brillouin zone. The Hamiltonian includes\nthe effect of spin-orbit coupling, strain and external electric and magnetic\nfields."
    },
    {
        "anchor": "Manifestation of the magnetic depopulation of one-dimensional subbands\n  in the optical absorption of acoustic magnetoplasmons in side-gated quantum\n  wires: We have investigated experimentally and theoretically the far-infrared (FIR)\nabsorption of gated, deep-mesa-etched GaAs/Al$_x$Ga$_{1-x}$As quantum wires. To\novercome Kohn's theorem we have in particular prepared double-layered wires and\nstudied the acoustic magnetoplasmon branch. We find oscillations in the\nmagnetic-field dispersion of the acoustic plasmon which are traced back to the\nself-consistently screened density profile in its dependence on the magnetic\ndepopulation of the one-dimensional subbands.",
        "positive": "Interacting resonant level coupled to a Luttinger liquid: Population vs.\n  density of states: We consider the problem of a single level quantum dot coupled to the edge of\na one-dimensional Luttinger liquid wire by both a hopping term and\nelectron-electron interactions. Using bosonization and Coulomb gas mapping of\nthe Anderson-Yuval type we show that thermodynamic properties of the level, in\nparticular, its occupation, depend on the various interactions in the system\nonly through a single quantity --- the corresponding Fermi edge singularity\nexponent. However, dynamical properties, such as the level density of states,\ndepend in a different way on each type of interaction. Hence, we can construct\ndifferent models, with and without interactions in the wire, with equal Fermi\nedge singularity exponents, which have identical population curves, although\nthey originate from very different level densities of states. The latter may\neither be regular or show a power-law suppression or enhancement at the Fermi\nenergy. These predictions are verified to a high degree of accuracy using the\ndensity matrix renormalization group algorithm to calculate the dot occupation,\nand classical Monte Carlo simulations on the corresponding Coulomb gas model to\nextract the level density of states."
    },
    {
        "anchor": "Thermal Conductance of Ballistic Point Contacts: We study the thermal conductance of ballistic point contacts. These contacts\nare realized as few nanometer long pillars in so called air-gap\nheterostructures (AGHs). The pillar length being much smaller that the mean\nfree path of the phonons up to room temperature. Due to the small dimension and\nthe low density of the pillars the thermal conductance of the AGHs is several\norders of magnitude reduced in comparison to bulk structures. The measurement\nresults are in quantitative agreement with a simple model that based on the\nBoltzmann transport equation.",
        "positive": "Density-matrix theory of the optical dynamics and transport in quantum\n  cascade structures: The role of coherence: The impact of coherence on the nonlinear optical response and stationary\ntransport is studied in quantum cascade laser structures. Nonequilibrium\neffects such as pump-probe signals, the spatio-temporally resolved electron\ndensity evolution, and the subband population dynamics (Rabi flopping) as well\nas the stationary current characteristics are investigated within a microscopic\ndensity-matrix approach. Focusing on the stationary current and the recently\nobserved gain oscillations, it is found that the inclusion of coherence leads\nto observable coherent effects in opposite parameter regimes regarding the\nrelation between the level broadening and the tunnel coupling across the main\ninjection barrier. This shows that coherence plays a complementary role in\nstationary transport and nonlinear optical dynamics in the sense that it leads\nto measurable effects in opposite regimes. For this reason, a fully coherent\nconsideration of such nonequilibrium structures is necessary to describe the\ncombined optical and transport properties"
    },
    {
        "anchor": "Direction-Controlled Chemical Doping for Reversible G-Phonon Mixing in\n  ABC Trilayer Graphene: Not only the apparent atomic arrangement but the charge distribution also\ndefines the crystalline symmetry that dictates the electronic and vibrational\nstructures. In this work, we report reversible and direction-controlled\nchemical doping that modifies the inversion symmetry of AB-bilayer and\nABCtrilayer graphene. For the top-down and bottom-up hole injection into\ngraphene sheets, we employed molecular adsorption of electronegative I2 and\nannealing-induced interfacial hole doping, respectively. The chemical breakdown\nof the inversion symmetry led to the mixing of the G phonons, Raman active Eg\nand Raman-inactive Eu modes, which was manifested as the two split G peaks, G-\nand G+. The broken inversion symmetry could be recovered by removing the hole\ndopants by simple rinsing or interfacial molecular replacement. Alternatively,\nthe symmetry could be regained by double-side charge injection, which\neliminated G- and formed an additional peak, Go, originating from the barely\ndoped interior layer. Chemical modification of crystalline symmetry as\ndemonstrated in the current study can be applied to other low dimensional\ncrystals in tuning their various material properties.",
        "positive": "Mesoscopic Coulomb Blockade in One-channel Quantum Dots: Signatures of \"mesoscopic Coulomb blockade\" are reported for quantum dots\nwith one fully transmitting point-contact lead, T1 = 1, T2 << 1. Unlike Coulomb\nblockade (CB) in weak-tunneling devices (T1, T2 << 1), one-channel CB is a\nmesoscopic effect requiring quantum coherence. Several distinctive features of\nmesoscopic CB are observed, including a reduction in CB upon breaking\ntime-reversal symmetry with a magnetic field, relatively large fluctuations of\npeak position as a function of magnetic field, and strong temperature\ndependence on the scale of the quantum level spacing."
    },
    {
        "anchor": "Integer Quantum Hall Effect in Graphene Channel with p-n Junction at\n  Domain Wall in Ferroelectric Substrate: We revealed that 180 degree ferroelectrics domain walls (FDWs) in a\nferroelectric substrate, which induce p-n junctions in a graphene channel, lead\nto the nontrivial temperature and gate voltage dependences of the perpendicular\nand parallel modes of the integer quantum Hall effect. In particular the number\nof perpendicular modes v, corresponding to the p-n junction across the graphene\nchannel varies with gate voltage increase from small integers to higher\nfractional numbers, e.g.v=1, 1.5, 2, ... 5.1,..9.1, 23 in the vicinity of the\ntransition from ferroelectric to paraelectric phase.These numbers and their\nirregular sequence principally differ from the sequence of fractional numbers\nv=1.5,2.5,... reported earlier. The origin of the unusual v-numbers is\nsignificantly different numbers of the edge modes, v1 and v2, corresponding to\nsignificantly different concentration of carriers in the left (n1) and right\n(n1) domains of p-n junction boundary. The concentrations n1 and n2 are\ndetermined by the gate voltage and polarization contributions, and so their\ndifference originates from the different direction of spontaneous polarization\nin different domains of ferroelectric substrate. The difference between n1 and\nn2 disappears with the vanishing of spontaneous polarization in a paraelectric\nphase. The phase transition from the ferroelectric to paraelectric phase can\ntake place either with the temperature increase (temperature-induced phase\ntransition) or with the decrease of ferroelectric substrate thickness\n(thickness-induced phase transition).",
        "positive": "Electronic confinement in quantum dots of twisted bilayer graphene: Electronic properties of quantum dots (QDs) depend sensitively on their\nparent materials. Therefore, confined electronic states in graphene QDs (GQDs)\nof monolayer and Bernal-stacked bilayer graphene are quite different. Twisted\nbilayer graphene (TBG) is distinct from monolayer and Bernal-stacked bilayer\ngraphene because of the new degree of freedom: twist angle. In the past few\nyears, numerous efforts have been made to realize the GQDs of monolayer and\nBernal-stacked bilayer graphene and achieved great success. Thus far, however,\nstrategies for realizing GQDs of TBG have been elusive. Here, we demonstrate a\ngeneral approach for fabricating stationary GQDs of TBG by introducing\nnanoscale p-n junctions with sharp boundaries in the TBG. We verify the\nconfinement of low-energy massless Dirac fermions via whispering-gallery modes\nin the GQDs of TBG. Unexpectedly, electronic states around van Hove\nsingularities of the TBG are also strongly modified around the GQDs. Such a\nfeature has never been reported and is attributed to spatial variation of the\ninterlayer coupling in the TBG induced by the GQDs."
    },
    {
        "anchor": "Time Reversal Invariant Topologically Insulating Circuits: From studies of exotic quantum many-body phenomena to applications in\nspintronics and quantum information processing, topological materials are\npoised to revolutionize the condensed matter frontier and the landscape of\nmodern materials science. Accordingly, there is a broad effort to realize\ntopologically non-trivial electronic and photonic materials for fundamental\nscience as well as practical applications. In this work, we demonstrate the\nfirst simultaneous site- and time- resolved measurements of a time reversal\ninvariant topological band-structure, which we realize in a radio frequency\n(RF) photonic circuit. We control band-structure topology via local permutation\nof a traveling wave capacitor-inductor network, increasing robustness by going\nbeyond the tight-binding limit. We observe a gapped density of states\nconsistent with a modified Hofstadter spectrum at a flux per plaquette of\n$\\phi=\\pi/2$. In-situ probes of the band-gaps reveal spatially-localized\nbulk-states and de-localized edge-states. Time-resolved measurements reveal\ndynamical separation of localized edge-excitations into spin-polarized\ncurrents. The RF circuit paradigm is naturally compatible with non-local\ncoupling schemes, allowing us to implement a M\\\"{o}bius strip topology\ninaccessible in conventional systems. This room-temperature experiment\nilluminates the origins of topology in band-structure, and when combined with\ncircuit quantum electrodynamics (QED) techniques, provides a direct path to\ntopologically-ordered quantum matter.",
        "positive": "Topology and exceptional points of massive Dirac models with generic\n  non-Hermitian perturbations: Recently, there has been a lot of activity in the research field of\ntopological non-Hermitian physics, partly driven by fundamental interests and\npartly driven by applications in photonics. However, despite these activities,\na general classification and characterization of non-Hermitian Dirac models\nthat describe the experimental systems is missing. Here, we present a\nsystematic investigation of massive Dirac models on periodic lattices,\nperturbed by general non-Hermitian terms. We find that there are three\ndifferent types of non-Hermitian terms. For each case we determine the bulk\nexceptional points, the boundary modes, and the band topology. Our findings\nserve as guiding principles for the design of applications, for example, in\nphotonic lattices. For instance, periodic Dirac systems with non-Hermitian mass\nterms can be used as topological lasers. Periodic Dirac systems with\nnon-Hermitian anti-commuting terms, on the other hand, exhibit exceptional\npoints at the surface, whose non-trivial topology could be utilized for optical\ndevices."
    },
    {
        "anchor": "Surface photocurrent in electron gas over liquid He subject to\n  quantizing magnetic field: The photogalvanic effect is studied in electron gas over the liquid He\nsurface with the presence of quantizing magnetic field. The gas is affected by\nthe weak alternating microwave electric field tilted towards the surface\nnormal. Both linear and circular photogalvanic effects are studied. The current\noccurs via indirect phototransition with the participation of ripplons emission\nor absorption. The photogalvanic tensor has strong resonances at the microwave\nfrequency $\\omega$ approaching to the frequencies of transitions between\nsize-quantized subbands.\n  The resonances are symmetric or antisymmetric, depending on a tensor\ncomponent. Other resonances appear at $\\omega\\approx n \\omega_c$, where $n$\nbeing integer and $\\omega_c$ is the cyclotron frequency. It is found that the\nlatter resonances split to two peaks connected with emission or absorption of\nripplons. The calculated photogalvanic coefficients are in accord with the\nexperimental observed values.",
        "positive": "Recovery of a SINIS turnstile accuracy in a strongly non-equilibrium\n  regime: We perform a theoretical study of non-equilibrium effects in charge transport\nthrough a hybrid single-electron transistor based on a small normal metal (N)\nisland with the gate-controlled number of electrons, tunnel-coupled to\nvoltage-biased superconducting (S) electrodes (SINIS). Focusing on the\nturnstile mode of the transistor operation with the gate voltage driven\nperiodically, and electrons on the island being out of equilibrium, we find\nthat the current quantization accuracy is a non-monotonic function of the\nrelaxation rate $\\Gamma_{\\mathcal{F}}$ of the distribution function\n$\\mathcal{F}(\\epsilon)$ on the island due to tunneling, as compared to the\ndrive frequency $f$, electron-electron $1/\\tau_{ee}$ and electron-phonon\n$1/\\tau_{eph}$ relaxation rates. Surprisingly, in the strongly non-equilibrium\nregime, $f\\gg \\Gamma_{\\mathcal{F}}\\gg\\tau_{ee}^{-1},\\tau_{eph}^{-1}$, the\nturnstile current plateau is recovered, similarly to the ideal equilibrium\nregime, $\\tau_{eph}^{-1}\\gg \\Gamma_{\\mathcal{F}}$. The plateau is destroyed in\nthe quasiequilibrium regime when the electron-electron relaxation is faster\nthan tunneling."
    },
    {
        "anchor": "Connecting the numerical and analytical ionization times for quantum\n  dots in semiconductor wires driven by alternating field: Recent numerical results for ionization of quantum dots by periodic electric\nfield during the electric dipole spin resonance are compared with known\nanalytical approaches. It is found that in finite-length quantum wires the\nnumerical ionization rate is slower than the analytical one, especially for low\ndriving field when the confinement potential strongly affects the dynamics.\nStill, the analytically predicted ionization times are in satisfactory\ncorrespondence with mean energy threshold times when the energy crosses the\nborder between localized and continuum states.",
        "positive": "Analytical and numerical $K_u - B$ phase diagrams for cobalt\n  nanostructures: stability region for a Bloch skyrmion: In this letter we calculate the energies corresponding to the different\nmagnetic phases present in a ferromagnetic cylinder by means of analytical\ncalculations. From the comparison of these energies, it is possible to\nconstruct magnetic phase diagrams as a function of the uniaxial anisotropy of\nthe sample and the external magnetic field applied. As proof of concept, we\nanalyzed the magnetic phase diagrams for a cobalt dot of 240 nm in diameter and\n70 nm in length, with an easy axis parallel to the dot axis, and with a\nmagnetic field applied towards or perpendicular to this axis. From these\ndiagrams we have obtained the stability regions for a Bloch skyrmion (Sk), a\nvortex core (VC) and a ferromagnetic (F) configuration, which can point in any\n$\\psi$ direction. Our results provide a pathway to engineer the formation and\ncontrollability of a skyrmion in a ferromagnetic dot to different anisotropy\nconstants and magnetic fields."
    },
    {
        "anchor": "Magnetic phase transitions in ultrathin films of different crystal\n  structures: The properties of ultrathin films have been studied within the framework of\nIsing model and the method of random-field interactions. It is shown that the\nCurie temperature is inversely proportional to the number of layers. Critical\nexponent $\\nu$ has been obtained and it is shown that it does not depend on the\ntype of crystalline lattice.",
        "positive": "Ultrafast Hidden Spin Polarization Dynamics of Bright and Dark Excitons\n  in 2H-WSe$_2$: We performed spin-, time- and angle-resolved extreme ultraviolet\nphotoemission spectroscopy (STARPES) of excitons prepared by photoexcitation of\ninversion-symmetric 2H-WSe$_2$ with circularly polarized light. The very short\nprobing depth of XUV photoemission permits selective measurement of\nphotoelectrons originating from the top-most WSe$_2$ layer, allowing for direct\nmeasurement of hidden spin polarization of bright and momentum-forbidden dark\nexcitons. Our results reveal efficient chiroptical control of bright excitons'\nhidden spin polarization. Following optical photoexcitation, intervalley\nscattering between nonequivalent K-K' valleys leads to a decay of bright\nexcitons' hidden spin polarization. Conversely, the ultrafast formation of\nmomentum-forbidden dark excitons acts as a local spin polarization reservoir,\nwhich could be used for spin injection in van der Waals heterostructures\ninvolving multilayer transition metal dichalcogenides."
    },
    {
        "anchor": "Jackiw-Rebbi zero modes in non-uniform topological insulator nanowire: We theoretically investigate the emergence of Jackiw-Rebbi zero modes and\ntheir conductance signature in non-uniform topological insulator nano-wires. We\nmodelled the non-uniform nano-wires as junction between two cylindrical\nnano-wires with different radius. In the limit of wire length being much larger\nthan its radius, the surface state of the nanowire splits into one dimensional\nDirac modes propagating along the axis of the cylinder owing to radial\nconfinement. The sign of the mass gap in each of these Dirac mode is decided by\nangular momentum quantum number corresponding to the rotational motion of the\nelectron about the axis of the cylindrical. Application of an external magnetic\nflux through the cylindrical nanowires enables us to tune the mass gap from\npositive to negative value across the junction. Due to this flux tunable band\ninversion, controlled by the external magnetic filed, Jackiw-Rebbi zero modes\ncan be made to appear or disappear at the junction. We compute differential\nconductance of our topological insulator nanowire junction and show that a\nquantized conductance peak appears at zero-energy (zero-bias) in the presence\nof the Jackiw-Rebbi mode.",
        "positive": "Optical Coherent Injection of Carrier and Current in Twisted Bilayer\n  graphene: We theoretically investigate optical injection processes, including one- and\ntwo-photon carrier injection and two-color coherent current injection, in\ntwisted bilayer graphene with moderate angles. The electronic states are\ndescribed by a continuum model, and the spectra of injection coefficients are\nnumerically calculated for different chemical potentials and twist angles,\nwhere the transitions between different bands are understood by the electron\nenergy resolved injection coefficients. The comparison with the injection in\nmonolayer graphene shows the significance of the interlayer coupling in the\ninjection processes. For undoped twisted bilayer graphene, all spectra of\ninjection coefficients can be divided into three energy regimes, which vary\nwith the twist angle. For very low photon energies in the linear dispersion\nregime, the injection is similar to graphene with a renormalized Fermi velocity\ndetermined by the twist angle; for very high photon energies where the\ninterlayer coupling is negligible, the injection is the same as that of\ngraphene; and in the middle regime around the transition energy of the Van Hove\nsingularity, the injection shows fruitful fine structures. Furthermore, the\ntwo-photon carrier injection diverges for the photon energy in the middle\nregime due to the existence of double resonant transitions."
    },
    {
        "anchor": "Observation of spin-orbit coupling induced Weyl points and topologically\n  protected Kondo effect in a two-electron double quantum dot: Recent years have brought an explosion of activities in the research of\ntopological aspects of condensed-matter systems. Topologically non-trivial\nphases of matter are typically accompanied by protected surface states or\nexotic degenerate excitations such as Majorana end states or Haldane's\nlocalized spinons. Topologically protected degeneracies can, however, also\nappear in the bulk. An intriguing example is provided by Weyl semimetals, where\ntopologically protected electronic band degeneracies and exotic surface states\nemerge even in the absence of interactions. Here we demonstrate experimentally\nand theoretically that Weyl degeneracies appear naturally in an interacting\nquantum dot system, for specific values of the external magnetic field. These\nmagnetic Weyl points are robust against spin-orbit coupling unavoidably present\nin most quantum dot devices. Our transport experiments through an InAs double\ndot device placed in magnetic field reveal the presence of a pair of Weyl\npoints, exhibiting a robust ground state degeneracy and a corresponding\nprotected Kondo effect.",
        "positive": "Non-equilibrium 1D many-body problems and asymptotic properties of\n  Toeplitz determinants: Non-equilibrium bosonization technique facilitates the solution of a number\nof important many-body problems out of equilibrium, including the Fermi-edge\nsingularity, the tunneling spectroscopy and full counting statistics of\ninteracting fermions forming a Luttinger liquid. We generalize the method to\nnon-equilibrium hard-core bosons (Tonks-Girardeau gas) and establish\ninterrelations between all these problems. The results can be expressed in\nterms of Fredholm determinants of Toeplitz type. We analyze the long time\nasymptotics of such determinants, using Szeg\\H{o} and Fisher-Hartwig theorems.\nOur analysis yields dephasing rates as well as power-law scaling behavior, with\nexponents depending not only on the interaction strength but also on the\nnon-equilibrium state of the system."
    },
    {
        "anchor": "Landauer Conductance without Two Chemical Potentials: We present a theory of the four--terminal conductance for the multi-channel\ntunneling barrier, which is based on the self-consistent solution of\nShrodinger, Poisson and continuity equations. We derive new results for the\ncase of a barrier embedded in a long wire with and without disorder. We also\nrecover known expressions for the conductance of the barrier placed into a\nballistic constriction. Our approach avoids a problematic use of two chemical\npotentials in the same system.",
        "positive": "Spin wave imaging in atomically designed nanomagnets: The spin dynamics of all ferromagnetic materials are governed by two types of\ncollective excitations: spin waves and domain walls. The fundamental processes\nunderlying these collective modes, such as exchange interactions and magnetic\nanisotropy, all originate at the atomic scale; yet, conventional probing\ntechniques, based on neutron and photon scattering, provide high resolution in\nreciprocal space, and thereby poor spatial resolution. Here we present direct\nimaging of spin waves in individual chains of ferromagnetically coupled $S=2$\nFe atoms, assembled one by one on a Cu$_2$N surface using a scanning tunnelling\nmicroscope. We are able to map the spin dynamics of these designer nanomagnets\nwith atomic resolution, in two complementary ways. First, atom to atom\nvariations of the amplitude of the quantized spin wave excitations, predicted\nby theory, are probed using inelastic electron tunnelling spectroscopy. Second,\nwe observe slow stochastic switching between two opposite magnetisation states,\nwhose rate varies strongly depending on the location of the tip along the\nchain. Our observations, combined with model calculations, reveal that switches\nof the chain are initiated by a spin wave excited state which has its antinodes\nat the edges of the chain, followed by a domain wall shifting through the chain\nfrom one end to the other. This approach opens the way towards atomic scale\nimaging of other types of spin excitations, such as spinons and fractional\nend-states, in engineered spin chains."
    },
    {
        "anchor": "Nonadiabatic noncyclic geometric phase of a spin-1/2 particle subject to\n  an arbitrary magnetic field: We derive a formula of the nonadiabatic noncyclic Pancharatnam phase for a\nquantum spin-1/2 particle subject to an arbitrary magnetic field. The formula\nis applied to three specific kinds of magneic fields. (i) For an orientated\nmagnetic field, the Pancharatnam phase is derived exactly. (ii) For a rotating\nmagnetic field, the evolution equation is solved analytically. The\nAharonov-Anandan phase is obtained exactly and the Pancharatnam phase is\ncomputed numerically. (iii) We propose a kind of topological transition in\none-dimensional mesoscopic ring subject to an in-plane magnetic field, and then\naddress the nonadiabatic noncyclic effect on this phenomenon.",
        "positive": "Anomalous Magnetic Susceptibility and Hall Effect from Valley Degrees of\n  Freedom: We study the magnetic and transport properties of epitaxial graphene films in\nthis letter. We predict enhanced signal of magnetic susceptibility and relate\nit to the intrinsic valley magnetic moments. There is also an anomalous\ncontribution to the ordinary Hall effect, which is due to the valley dependent\nBerry phase or valley-orbit coupling."
    },
    {
        "anchor": "Opposite current-induced spin polarizations in bulk-metallic Bi2Se3 and\n  bulk-insulating Bi2Te2Se topological insulator thin flakes: One of the most fundamental and exotic properties of 3D topological\ninsulators (TIs) is spin-momentum-locking (SML) of their topological surface\nstates (TSSs), promising for potential applications in future spintronics.\nHowever, other possible conduction channels, such as a trivial two-dimensional\nelectron gas (2DEG) with strong Rashba type spin-orbit interaction (SOI) and\nbulk conducting states that may possess a spin Hall effect (SHE), can coexist\nin 3D TIs, making determining the origin of the current induced spin\npolarization (CISP) difficult. In this work, we directly compared the CISP\nbetween bulk-insulating Bi2Te2Se (BTS221) and bulk-metallic Bi2Se3 thin flakes\nusing spin potentiometry. In the bulk insulating BTS221, the observed CISP has\na sign consistent with the expected helicity of the SML of the TSS, but an\nopposite sign to its calculated bulk spin Hall conductivity (SHC). However,\ncompared to BTS221, an opposite CISP is observed in the bulk metallic Bi2Se3,\nconsistent instead with both the expectations of its Rashba-Edelstein effect of\nthe band-bending induced 2DEG and bulk spin Hall Effect (SHE). Our results\nprovide an electrical way to distinguish the TSS from other possible conducting\nchannels in spin transport measurements on 3D TIs, and open ways for the\npotential applications in charge-spin conversion devices.",
        "positive": "Impact of heavy hole-light hole coupling on optical selection rules in\n  GaAs quantum dots: We report strong heavy hole-light mixing in GaAs quantum dots grown by\ndroplet epitaxy. Using the neutral and charged exciton emission as a monitor we\nobserve the direct consequence of quantum dot symmetry reduction in this strain\nfree system. By fitting the polar diagram of the emission with simple\nanalytical expressions obtained from k$\\cdot$p theory we are able to extract\nthe mixing that arises from the heavy-light hole coupling due to the\ngeometrical asymmetry of the quantum dot."
    },
    {
        "anchor": "Long range Josephson coupling through ferromagnetic graphene: We study the Josephson effect in graphene-based ballistic\nsuperconductor-ferromagnet-superconductor (SFS) junctions. We find an\noscillatory Josephson coupling $I_c R_N$ of F graphene whose amplitude is\nnonvanishing for a half-metallic graphene, increases for the exchange fields\n$h$ above the Fermi energy $E_{F}$ and shows only a slow damping at strong\nexchange fields $h\\gg E_{F}$. We interpret this long range Josephson coupling\nas the result of the exchange mediated Andreev-Klein process at FS interfaces\nwhich enhances the induced antiparallel-spin superconducting correlations in F\ngraphene by increasing $h$ above $E_{F}$. We further demonstrate the existence\nof regular temperature induced transitions between 0 and $\\pi$ couplings in the\nplane of $T$ and $h$ where the phase boundaries have distinct shapes at the two\nregimes of $h$ below and above $E_{F}$.",
        "positive": "Criticality of the metal-topological insulator transition driven by\n  disorder: Employing scaling analysis of the localization length, we deduce the critical\nexponent of the metal-topological insulator (TI) transitions induced by\ndisorder. The obtained exponent nu~2.7 shows no conspicuous deviation from the\nvalue established for metal-ordinary insulator transitions in systems of the\nsymplectic class. We investigate the topological phase diagram upon carrier\ndoping to reveal the nature of the so-called topological Anderson insulator\n(TAI) region. The critical exponent of the metal-TAI transition is also first\nestimated, shown to be undistinguishable from the above value within the\nnumerical error. By symmetry considerations we determine the explicit form of\nRashba spin-orbit coupling in systems of C4v point group symmetry."
    },
    {
        "anchor": "Coherent radiation by molecular magnets: The possibility of coherent radiation by molecular magnets is investigated.\nIt is shown that to realize the coherent radiation, it is necessary to couple\nthe considered sample to a resonant electric circuit. A theory for describing\nthis phenomenon is developed, based on a realistic microscopic Hamiltonian,\nincluding the Zeeman terms, single-site anisotropy, and dipole interactions.\nThe role of hyperfine interactions between molecular and nuclear spins is\nstudied. Numerical solutions of the spin evolution equations are presented.",
        "positive": "2D topological matter from a boundary Green's functions perspective:\n  Faddeev-LeVerrier algorithm implementation: Since the breakthrough of twistronics a plethora of topological phenomena in\ntwo dimensions has appeared, specially relating topology and electronic\ncorrelations. These systems can be typically analyzed in terms of lattice\nmodels of increasing complexity using Green's function techniques. In this work\nwe introduce a general method to obtain the boundary Green's function of such\nmodels taking advantage of the numerical Faddeev-LeVerrier algorithm to\ncircumvent some analytical constraints of previous works. As an illustration we\napply our formalism to analyze the edge features of Chern insulators,\ntopological superconductors as the Kitaev square lattice and the Checkerboard\nlattice in the flat band topological regime. The efficiency of the method is\ndemonstrated by comparison to standard recursive Green's function calculations."
    },
    {
        "anchor": "Casimir momentum of magneto-chiral matter: We consider a scattering formulation of radiative momentum transfer to a\nMagneto-Chiral system that is subjected to a constant background magnetic\nfield. The system takes the form of a collection magnetic dipoles that exhibit\nthe Faraday effect. It is shown that the first non-trivial contribution of the\nmomentum transfer to the object from the radiation field occurs at fourth order\nin the Born series.",
        "positive": "High-Sensitivity, High-Resolution Detection of Reactive Oxygen-Species\n  Concentration Using NV Centers: Nitrogen-vacancy (NV) color centers in diamond have been demonstrated as\nuseful magnetic sensors, in particular for measuring spin fluctuations,\nachieving high sensitivity and spatial resolution. These abilities can be used\nto explore various biological and chemical processes, catalyzed by Reactive\nOxygen Species (ROS). Here we demonstrate a novel approach to measure and\nquantify Hydroxyl radicals with high spatial resolution, using the fluorescence\ndifference between NV charged states. According to the results, the achieved NV\nsensitivity is $11 \\pm 4 \\frac{nM}{\\sqrt Hz}$, realized in-situ without spin\nlabels and localized to a volume of $\\sim 10$ picoliter."
    },
    {
        "anchor": "Casimir interaction of arbitrarily shaped conductors: We review a systematic practical implementation of the multiple scattering\nformalism due to Balian and Duplantier [R. Balian and B. Duplantier, Ann. Phys.\n(NY) \\textbf{104}, 300 (1977); \\textbf{112}, 165 (1978)] for the calculation of\nthe Casimir interaction between arbitrarily shaped smooth conductors. The\nleading two-point scattering term of the expansion has a simple compact form,\namenable to exact or accurate numerical evaluation. It is a general expression\nwhich improves upon the proximity force and pairwise summation approximations.\nWe show that for many geometries it captures the bulk of the interaction\neffect. The inclusion of terms beyond the two-point approximation provides an\naccuracy check and explains screening. As an illustration of the power and\nversatility of the method we re-evaluate sphere-sphere and sphere-plane\ninteractions and compared the results with previous findings that employed\ndifferent methods. We also compute for the first time interaction of a\nhyperboloid (mimicking an atomic force microscope tip) and a plane. We also\nanalyze the anomalous situations involving long cylindrical conductors where\nthe two-point scattering approximation fails qualitatively. In such cases\nanalytic summation of the entire scattering series is carried out and a\ntopological argument is put forward as an explanation of the result. We give\nthe extension of this theory to the case of finite temperatures where the\ntwo-point scattering approximation result has a simple compact form, also\namenable to exact or accurate numerical evaluation.",
        "positive": "Ground-state properties of gapped graphene using the random phase\n  approximation: We study the effect of band gap on the ground-state properties of Dirac\nelectrons in a doped graphene within the random phase approximation at zero\ntemperature. Band gap dependence of the exchange, correlation and ground-state\nenergies and the compressibility are calculated. We additionally show that the\nconductance in the gapped graphene is smaller than gapless one. We also\ncalculate the band gap dependence of charge compressibility and it decreases\nwith increasing the band gap values."
    },
    {
        "anchor": "Electric Multipole Moments, Topological Multipole Moment Pumping, and\n  Chiral Hinge States in Crystalline Insulators: We extend the theory of dipole moments in crystalline insulators to higher\nmultipole moments. In this paper, we expand in great detail the theory\npresented in Ref. 1, and extend it to cover associated topological pumping\nphenomena, and a novel class of 3D insulator with chiral hinge states. In\nquantum-mechanical crystalline insulators, higher multipole bulk moments\nmanifest themselves by the presence of boundary-localized moments of lower\ndimension, in exact correspondence with the electromagnetic theory of classical\ncontinuous dielectrics. In the presence of certain symmetries, these moments\nare quantized, and their boundary signatures are fractionalized. These\nmultipole moments then correspond to new SPT phases. The topological structure\nof these phases is described by \"nested\" Wilson loops, which reflect the\nbulk-boundary correspondence in a way that makes evident a hierarchical\nclassification of the multipole moments. Just as a varying dipole generates\ncharge pumping, a varying quadrupole generates dipole pumping, and a varying\noctupole generates quadrupole pumping. For non-trivial adiabatic cycles, the\ntransport of these moments is quantized. An analysis of these interconnected\nphenomena leads to the conclusion that a new kind of Chern-type insulator\nexists, which has chiral, hinge-localized modes in 3D. We provide the minimal\nmodels for the quantized multipole moments, the non-trivial pumping processes\nand the hinge Chern insulator, and describe the topological invariants that\nprotect them.",
        "positive": "An energy-resolved atomic scanning probe: We propose a method to probe the local density of states (LDOS) of atomic\nsystems that provides both spatial and energy resolution. The method combines\natomic and tunneling techniques to supply a simple, yet quantitative and\noperational, definition of the LDOS for both interacting and non-interacting\nsystems: It is the rate at which particles can be siphoned from the system of\ninterest by a narrow energy band of non-interacting states contacted locally to\nthe many-body system of interest. Ultracold atoms in optical lattices are a\nnatural platform for implementing this broad concept to visualize the energy\nand spatial dependence of the atom density in interacting, inhomogeneous\nlattices. This includes models of strongly correlated condensed matter systems,\nas well as ones with non-trivial topologies."
    },
    {
        "anchor": "Size quantization of charge carriers in lead salt cylindrical quantum\n  wires: A formalism for determining energy eigenstates of cylindrical lead salt\nquantum wires in the multiple-band envelope-function approximation is\ndeveloped. Electron energy dispersion for quantum wire subbands within the\nconduction and valence bands is found.",
        "positive": "Classical and quantum capacitances calculated locally considering a\n  two-dimensional Hall bar: In this work we investigate the electrostatic properties of two dimensional\nelectron system (2DES) in the integer quantum Hall regime. The alternating\nscreening properties of compressible and incompressible strips are formed due\nto edge effects together with electron-electron interactions. As it is well\nknown, the Landau quantization emanates from strong perpendicular magnetic\nfields. The (Landau) energy levels are broadened due to impurities, which we\nembedded their effects in density of states (DOS). In a basic level DOS has two\ndifferent forms: the Gaussian and semi-elliptic descriptions. The second form\nis calculated within the self consistent Born approximation (SCBA). Having in\nhand the density of states, we obtain both the longitudinal and Hall\n(transversal) conductivities ($\\sigma_{l}, \\sigma_{H}$) utilizing\nThomas-Fermi-Poisson approximation to calculate position dependent charge\ndensity profile and use Drude formalism to obtain transport coefficients.\nSince, the definition of capacitance is closely related with compressibility\nvia DOS, (local) screening properties of 2DES is extremely important to\nunderstand local capacitances. Here we numerically simulate a translational\ninvariant Hall bar subject to high magnetic fields which is perpendicular to\nthe plane of the 2DES using realistic parameters extracted from the related\nexperiments. Using the above mentioned approaches the local capacitances are\ncalculated, numerically. Our findings are in perfect agreement with related\nexperimental results which are based on a dynamic scanning capacitance\nmicroscopy technique."
    },
    {
        "anchor": "Study of the ultrafast dynamics of ferromagnetic materials with a\n  Quantum Monte Carlo atomistic model: We study of the ultrafast dynamics of the atomic angular momentum in\nferrimagnets irradiated by laser pulses. My apply a quantum atomistic spin\napproach based on the Monte Carlo technique. Our model describes the coherent\ntransfer of angular momentum between the spin and the orbital momentum as well\nas the quenching of the orbital momentum induced by the lattice field. The\nElliott-Yafet collision mechanism is also included. We focus on elementary\nmechanisms that lead to the dissipation of the total angular momentum in a rare\nearth-transition metal (RE-TM) alloy in which the two sublattices have opposite\nspin orientation. Our model shows that the observed ultrafast quenching of the\nmagnetization can be explained microscopically by the transfer of spin between\nthe sublattices and by the quenching of the localized orbital angular momentum.",
        "positive": "Transport in two-dimensional topological materials: recent developments\n  in experiment and theory: We review theoretical and experimental highlights in transport in\ntwo-dimensional materials focussing on key developments over the last five\nyears. Topological insulators are finding applications in magnetic devices,\nwhile Hall transport in doped samples and the general issue of topological\nprotection remain controversial. In transition metal dichalcogenides\nvalley-dependent electrical and optical phenomena continue to stimulate\nstate-of-the-art experiments. In Weyl semimetals the properties of Fermi arcs\nare being actively investigated. A new field, expected to grow in the near\nfuture, focuses on the non-linear electrical and optical responses of\ntopological materials, where fundamental questions are once more being asked\nabout the intertwining roles of the Berry curvature and disorder scattering. In\ntopological superconductors the quest for chiral superconductivity, Majorana\nfermions and topological quantum computing is continuing apace."
    },
    {
        "anchor": "Spin susceptibility of two-dimensional electrons in narrow AlAs quantum\n  wells: We report measurements of the spin susceptibility in dilute two-dimensional\nelectrons confined to a 45$\\AA$ wide AlAs quantum well. The electrons in this\nwell occupy an out-of-plane conduction-band valley, rendering a system similar\nto two-dimensional electrons in Si-MOSFETs but with only one valley occupied.\nWe observe an enhancement of the spin susceptibility over the band value that\nincreases as the density is decreased, following closely the prediction of\nquantum Monte Carlo calculations and continuing at finite values through the\nmetal-insulator transition.",
        "positive": "Thermo-mechanical characterization of on-chip buckled dome Fabry-Perot\n  microcavities: We report on the thermomechanical and thermal tuning properties of\ncurved-mirror Fabry-Perot resonators, fabricated by the guided assembly of\ncircular delamination buckles within a multilayer a-Si/SiO2 stack. Analytical\nmodels for temperature dependence, effective spring constants, and mechanical\nmode frequencies are described and shown to be in good agreement with\nexperimental results. The cavities exhibit mode volumes as small as\n$\\sim10\\lambda^3$, reflectance-limited finesse $\\sim3\\times10^3$, and\nmechanical resonance frequencies in the MHz range. Monolithic cavity arrays of\nthis type might be of interest for applications in sensing, cavity quantum\nelectrodynamics, and optomechanics."
    },
    {
        "anchor": "Enhanced Rashba spin-orbit coupling in core-shell nanowires by the\n  interfacial effect: We report on $\\vec{k}\\cdot\\vec{p}$ calculations of Rashba spin-orbit coupling\ncontrolled by external gates in InAs/InAsP core-shell nanowires. We show that\ncharge spilling in the barrier material allows for a stronger symmetry breaking\nthan in homoegenous nano-materials, inducing a specific interface-related\ncontribution to spin-orbit coupling. Our results qualitatively agree with\nrecent experiments [S. Futhemeier \\textit{et al.}, Nat. Commun. \\textbf{7},\n12413 (2016)] and suggest additional wavefunction engineering strategies to\nenhance and control spin-orbit coupling.",
        "positive": "Direct observation of magnetic droplet solitons in all-perpendicular\n  spin torque nano-oscillators: Magnetic droplets are non-topological dynamical solitons that can be\nnucleated and sustained in nano-contact based spin torque nano-oscillators\n(NC-STNOs) with perpendicular anisotropy free layers. While originally\npredicted in all-perpendicular NC-STNOs, all experimental demonstrations have\nso far relied on orthogonal devices with an in-plane polarizing layer that\nrequires a strong magnetic field for droplet nucleation. Here, we instead show\nthe nucleation and sustained operation of magnetic droplets in\nall-perpendicular NC-STNOs in modest perpendicular fields and over a wide range\nof nano-contact size. The droplet is observed electrically as an intermediate\nresistance state accompanied by broadband low-frequency microwave noise. Using\ncanted fields, which introduce a non-zero relative angle between the free and\nfixed layer, the actual droplet precession frequency can also be determined.\nFinally, the droplet size, its perimeter width, and its fully reversed core are\ndirectly observed underneath a 80 nm diameter nano-contact using scanning\ntransmission x-ray microscopy on both the Ni and Co edges. The droplet diameter\nis 150 nm, i.e. almost twice the nominal size of the nano-contact, and the\ndroplet has a perimeter width of about 70 nm."
    },
    {
        "anchor": "Localization by interference: Square billiard with a magnetic flux: Eigenstates and energy levels of a square quantum billiard in a magnetic\nfield, or with an Aharonov-Bohm flux line, are found in quasiclassical\napproximation, that is, for high enough energy. Explicit formulas for the\nenergy levels and wavefunctions are found. There are localized states, never\nbefore noticed in this well studied problem, whose localization is due to phase\ninterference, even though there is no or negligible classical effect of the\nmagnetic field. These and related states account almost entirely for the\nmagnetic response in certain temperature ranges, and thus have a bearing on the\nexperiments of Levy et al.",
        "positive": "Quantum corrections to conductivity of disordered electrons due to\n  inelastic scattering off magnetic impurities: We study the quantum corrections to the conductivity of the two-dimensional\ndisordered interacting electron system in the diffusive regime due to inelastic\nscattering off rare magnetic impurities. We focus on the case of very different\ng-factors for electrons and magnetic impurities. Within the Born approximation\nfor the inelastic scattering off magnetic impurities we find additional\ntemperature-dependent corrections to the conductivity of the Altshuler-Aronov\ntype. Our results demonstrate that the low temperature transport in interacting\ndisordered electron systems with rare magnetic impurities is more interesting\nthan it was commonly believed on the basis of treatment of magnetic impurity\nspins as classical ones."
    },
    {
        "anchor": "Coupling and stacking order of ReS2 atomic layers revealed by\n  ultralow-frequency Raman spectroscopy: We investigate the ultralow-frequency Raman response of atomically thin ReS2,\na special type of two-dimensional (2D) semiconductors with unique distorted 1T\nstructure. Bilayer and few-layer ReS2 exhibit rich Raman spectra at frequencies\nbelow 50 cm-1, where a panoply of interlayer shear and breathing modes are\nobserved. The emergence of these interlayer phonon modes indicate that the ReS2\nlayers are coupled and stacked orderly, in contrast to the general belief that\nthe ReS2 layers are decoupled from one another. While the interlayer breathing\nmodes can be described by a linear chain model as in other 2D layered crystals,\nthe shear modes exhibit distinctive behavior due to the in-plane lattice\ndistortion. In particular, the two shear modes in bilayer ReS2 are\nnon-degenerate and well separated in the Raman spectrum, in contrast to the\ndoubly degenerate shear modes in other 2D materials. By carrying out\ncomprehensive first-principles calculations, we can account for the frequency\nand Raman intensity of the interlayer modes, and determine the stacking order\nin bilayer ReS2.",
        "positive": "A Two-dimensional Dirac fermion microscope: The electron microscope has been a powerful, highly versatile workhorse in\nthe fields of material and surface science, micro and nanotechnology, biology\nand geology, for nearly 80 years. The advent of two-dimensional materials opens\nnew possibilities for realising an analogy to electron microscopy in the solid\nstate. Here we provide a perspective view on how a two-dimensional (2D) Dirac\nfermion-based microscope can be realistically implemented and operated, using\ngraphene as a vacuum chamber for ballistic electrons. We use semiclassical\nsimulations to propose concrete architectures and design rules of 2D electron\nguns, deflectors, tunable lenses and various detectors. The simulations show\nhow simple objects can be imaged with well-controlled and collimated in-plane\nbeams consisting of relativistic charge carriers. Finally, we discuss the\npotential of such microscopes for investigating edges, terminations and\ndefects, as well as interfaces, including external nanoscale structures such as\nadsorbed molecules, nanoparticles or quantum dots."
    },
    {
        "anchor": "Angular momentum transfer via relativistic spin-lattice coupling from\n  first principles: The transfer and control of angular momentum is a key aspect for spintronic\napplications. Only recently, it was shown that it is possible to transfer\nangular momentum from the spin system to the lattice on ultrashort time scales.\nIn an attempt to contribute to the understanding of angular momentum transfer\nbetween spin and lattice degrees of freedom we present a scheme to calculate\nfully-relativistic spin-lattice coupling parameters from first-principles. By\ntreating changes in the spin configuration and atomic positions at the same\nlevel, closed expressions for the atomic spin-lattice coupling parameters can\nbe derived in a coherent manner up to any order. Analyzing the properties of\nthese parameters, in particular their dependence on spin-orbit coupling, we\nfind that even in bcc Fe the leading term for the angular momentum exchange\nbetween the spin system and the lattice is a Dzyaloshiskii-Moriya-type\ninteraction, which is due to the symmetry breaking distortion of the lattice.",
        "positive": "Zero field spin splitting in AlSb/InAs/AlSb quantum wells induced by\n  surface proximity effects: InAs quantum well heterostructures are of considerable interest for\nmesoscopic device applications such as scanning probe and magnetic recording\nsensors, which require the channel to be close to the surface. Here we report\non magnetotransport measurements of AlSb/InAs/AlSb Hall bars at a shallow depth\nof 20 nm. Analysis of the observed Shubnikov-de Haas oscillations and modeling\nshow that spin splitting energies in excess of 2.3 meV occur at zero magnetic\nfield. We conclude that the spin-splitting results from the Rashba effect due\nto the band bending in the quantum well. This is caused by substantial electron\ntransfer from the surface to the quantum well and becomes significant when the\nquantum well is located near the surface."
    },
    {
        "anchor": "Image potential states as quantum probe of graphene interfaces: Image potential states (IPSs) are electronic states localized in front of a\nsurface in a potential well formed by the surface projected bulk band gap on\none side and the image potential barrier on the other. In the limit of a\ntwo-dimensional solid a double Rydberg series of IPSs has been predicted which\nis in contrast to a single series present in three-dimensional solids. Here, we\nconfirm this prediction experimentally for mono- and bilayer graphene. The IPSs\nof epitaxial graphene on SiC are measured by scanning tunnelling spectroscopy\nand the results are compared to ab-initio band structure calculations. Despite\nthe presence of the substrate, both calculations and experimental measurements\nshow that the first pair of the double series of IPSs survives, and eventually\nevolves into a single series for graphite. Thus, IPSs provide an elegant\nquantum probe of the interfacial coupling in graphene systems.",
        "positive": "Thermoelectric properties of the Corbino disk in graphene: Thermopower and the Lorentz number for an edge-free (Corbino) graphene disk\nin the quantum Hall regime is calculated within the Landauer-B\\\"{u}ttiker\nformalism. We find, by varying the electrochemical potential, that amplitude of\nthe Seebeck coefficient follows a modified Goldsmid-Sharp relation, in which\nenergy gap is identified with the interval between zero-th and first Landau\nlevel in bulk graphene. Analogous relation for the Lorentz number is also\ndetermined. Therefore, these thermoelectric properties are solely defined by\nthe magnetic field, temperature, the Fermi velocity in graphene, and\nfundamental constants including the electrons charge, the Planck and Boltzmann\nconstants, being independent on the system geometric dimensions. This suggests\nthat the Corbino disk in graphene may operate as a thermoelectric thermometer,\nallowing to determine small temperature difference between two reservoirs, if\nmean temperature and magnetic field are known."
    },
    {
        "anchor": "Dephasing-assisted Gain and Loss in Mesoscopic Quantum Systems: Motivated by recent experiments, we analyse the phonon-assisted steady-state\ngain of a microwave field driving a double quantum-dot in a resonator. We apply\nthe results of our companion paper, which derives the complete set of\nfourth-order Lindblad dissipators using Keldysh methods, to show that resonator\ngain and loss are substantially affected by dephasing-assisted dissipative\nprocesses in the quantum-dot system. These additional processes, which go\nbeyond recently proposed polaronic theories, are in good quantitative agreement\nwith experimental observations",
        "positive": "Non-Markovian effects in the Quantum noise of interacting nanostructures: We present a theory of finite-frequency noise in non-equilibrium conductors.\nIt is shown that Non-Markovian correlations are essential to describe the\nphysics of quantum noise. In particular, we show the importance of a correct\ntreatment of the initial system-bath correlations, and how these can be\ncalculated using the formalism of quantum master equations. Our method is\nparticularly important in interacting systems, and when the measured\nfrequencies are larger that the temperature and applied voltage. In this\nregime, quantum-noise steps are expected in the power spectrum due to vacuum\nfluctuations. This is illustrated in the current noise spectrum of single\nresonant level model and of a double quantum dot --charge qubit-- attached to\nelectronic reservoirs. Furthermore, the method allows for the calculation of\nthe single-time counting statistics in quantum dots, measured in recent\nexperiments."
    },
    {
        "anchor": "Intershell resistance in multiwall carbon nanotubes: A Coulomb drag\n  study: We calculate the intershell resistance R_{21} in a multiwall carbon nanotube\nas a function of temperature T and Fermi level (e.g. a gate voltage), varying\nthe chirality of the inner and outer tubes. This is done in a so-called Coulomb\ndrag setup, where a current I_1 in one shell induces a voltage drop V_2 in\nanother shell by the screened Coulomb interaction between the shells neglecting\nthe intershell tunnelling. We provide benchmark results for R_{21}=V_2/I_1\nwithin the Fermi liquid theory using Boltzmann equations. The band structure\ngives rise to strongly chirality dependent suppression effects for the Coulomb\ndrag between different tubes due to selection rules combined with mismatching\nof wave vector and crystal angular momentum conservation near the Fermi level.\nThis gives rise to orders of magnitude changes in R_{21} and even the sign of\nR_{21} can change depending on the chirality of the inner and outer tube and\nmisalignment of inner and outer tube Fermi levels. However for any tube\ncombination, we predict a dip (or peak) in R_{21} as a function of gate\nvoltage, since R_{21} vanishes at the electron-hole symmetry point. As a\nbyproduct, we classified all metallic tubes into either zigzag-like or\narmchair-like, which have two different non-zero crystal angular momenta m_a,\nm_b and only zero angular momentum, respectively.",
        "positive": "Van Hove bound states in the continuum: Localised subradiant states in\n  finite open lattices: We show that finite lattices with arbitrary boundaries may support large\ndegenerate subspaces, stemming from the underlying translational symmetry of\nthe lattice. When the lattice is coupled to an environment, a potentially large\nnumber of these states remains weakly or perfectly uncoupled from the\nenvironment, realising a new kind of bound states in the continuum. These\nstates are strongly localized along particular directions of the lattice which,\nin the limit of strong coupling to the environment, leads to\nspatially-localized subradiant states."
    },
    {
        "anchor": "Magnetic field anti-symmetry of photovoltaic voltage in evanescent\n  microwave fields: A two dimensional electron system without spatial inversion symmetry develops\na sample specific dc voltage when exposed to a microwave radiation at low\ntemperature. We investigate this photovoltaic (PV) effect, in the case where\nspatial symmetry is broken by an evanescent high-frequency potential. We\nmeasure the induced PV voltage in a ${\\rm GaAs/Ga_{1-x}Al_{x}As}$ Hall bar at\nmagnetic fields in the Tesla range. We find that in this regime the induced PV\nvoltage is anti-symmetric with magnetic field, and exhibits regular\nShubnikov-de Haas like oscillations. Our experimental results can be understood\nfrom a simple model, which describes the effect of stationary orbital currents\ncaused by microwave driving.",
        "positive": "Quantum Hall Effect in Three Dimensional Layered Systems: Using a mapping of a layered three-dimensional system with significant\ninter-layer tunneling onto a spin-Hamiltonian, the phase diagram in the strong\nmagnetic field limit is obtained in the semi-classical approximation. This\nphase diagram, which exhibit a metallic phase for a finite range of energies\nand magnetic fields, and the calculated associated critical exponent,\n$\\nu=4/3$, agree excellently with existing numerical calculations. The\nimplication of this work for the quantum Hall effect in three dimensions is\ndiscussed."
    },
    {
        "anchor": "Optical Modulation Effects on Nonlinear Electron Transport in Graphene\n  in Terahertz Frequency Range: We describe very fast electron dynamics for a graphene nanoribbon driven by a\ncontrol electromagnetic field in the terahertz regime. The mobility as a\nfunction of bias possesses a large threshold value when entering a nonlinear\ntransport regime. This value depends on the temperature, electron density,\nimpurity scattering strength, nanoribbon width and correlation length for the\nline-edge roughness. An enhanced electron mobility beyond this threshold has\nbeen observed, which is related to the initially-heated electrons in high\nenergy states with a larger group velocity. However, this mobility enhancement\nquickly reaches a maximum governed by the Fermi velocity in graphene and the\ndramatically increased phonon scattering. Super-linear and sub-linear\ntemperature dependences of the mobility are seen in the linear and nonlinear\ntransport regimes, which is attributed separately to the results of sweeping\nelectrons from the right Fermi edge to the left one through elastic scattering\nand moving electrons from low-energy states to high-energy ones through\nfield-induced electron heating. The threshold field is pushed up by a decreased\ncorrelation length in the high field regime, and is further accompanied by a\nreduced magnitude in the mobility enhancement. This implies an anomalous\nhigh-field increase of the line-edge roughness scattering with decreasing\ncorrelation length due to the occupation of high-energy states by field-induced\nelectron heating. Additionally, a self-consistent device modeling has been\nproposed for graphene transistors under an optical modulation on its gate,\nwhich employs Boltzmann moment equations up to the third order for describing\nfast carrier dynamics and full wave electromagnetics coupled to the Boltzmann\nequation for describing spatial-temporal dependence of the total field.",
        "positive": "Near room-temperature memory devices based on hybrid spin-crossover SiO2\n  nanoparticles coupled to single-layer graphene nanoelectrodes: In this paper, we report on the charge transport properties of hybrid\nnanoparticles (NPs) based on the polymeric 1D compound [Fe(Htrz)2(trz)](BF4),\nwhich is one of the most promising SCO systems for designing electronic\ndevices. In particular, we used for the first time hybrid SCO NPs covered with\na silica shell and placed in between single-layer graphene electrodes. We\nevidence a reproducible thermal hysteresis loop in the conductance above\nroom-temperature, meaning that no degradation of the current levels has been\ndetected; we thus conclude that the robustness of the spin-transition is\nsignificantly improved as compared with previous results and with other reports\nwhere even larger assemblies and SCO objects were involved. This bistability\ncombined with the versatility of graphene represents a promising scenario for a\nvariety of technological applications but also for future sophisticated\nfundamental studies."
    },
    {
        "anchor": "Spin filters with Fano dots: We compute the zero bias conductance of electrons through a single ballistic\nchannel weakly coupled to a side quantum dot with Coulomb interaction. In\ncontrast to the standard setup which is designed to measure the transport\nthrough the dot, the channel conductance reveals Coulomb blockade dips rather\nthen peaks due to the Fano-like backscattering. At zero temperature the Kondo\neffect leads to the formation of broad valleys of small conductance\ncorresponding to an odd number of electrons on the dot. By applying a magnetic\nfield in the dot region we find two dips corresponding to a total suppression\nin the conductance of spins up and down separated by an energy of the order of\nthe Coulomb interaction. This provides a possibility of a perfect spin filter.",
        "positive": "Liquid n-hexane condensed in silica nanochannels: A combined optical\n  birefringence and vapor sorption isotherm study: The optical birefringence of liquid n-hexane condensed in an array of\nparallel silica channels of 7nm diameter and 400 micrometer length is studied\nas a function of filling of the channels via the vapor phase. By an analysis\nwith the generalized Bruggeman effective medium equation we demonstrate that\nsuch measurements are insensitive to the detailed geometrical (positional)\narrangement of the adsorbed liquid inside the channels. However, this technique\nis particularly suitable to search for any optical anisotropies and thus\ncollective orientational order as a function of channel filling. Nevertheless,\nno hints for such anisotropies are found in liquid n-hexane. The n-hexane\nmolecules in the silica nanochannels are totally orientationally disordered in\nall condensation regimes, in particular in the film growth as well as in the\nthe capillary condensed regime. Thus, the peculiar molecular arrangement found\nupon freezing of liquid n-hexane in nanochannel-confinement, where the\nmolecules are collectively aligned perpendicularly to the channels' long axes,\ndoes not originate in any pre-alignment effects in the nanoconfined liquid due\nto capillary nematization."
    },
    {
        "anchor": "Transport properties of quantum dots with hard walls: Quantum dots are fabricated in a Ga[Al]As-heterostructure by local oxidation\nwith an atomic force microscope. This technique, in combination with top gate\nvoltages, allows us to generate steep walls at the confining edges and small\nlateral depletion lengths. The confinement is characterized by low-temperature\nmagnetotransport measurements, from which the dots' energy spectrum is\nreconstructed. We find that in small dots, the addition spectrum can\nqualitatively be described within a Fock-Darwin model. For a quantitative\nanalysis, however, a hard-wall confinement has to be considered. In large dots,\nthe energy level spectrum deviates even qualitatively from a Fock-Darwin model.\nThe maximum wall steepness achieved is of the order of 0.4 meV/nm.",
        "positive": "Ab initio Study of Nonlinear Optical Susceptibilities in Silicon\n  Nanowires: Using Time Independent Density Functional Theory (TIDFT) it is shown that the\n2nd order optical susceptibilities of narrow (1nm-2nm) Silicon Nanowires (SiNW)\nare enhanced due to surface termination. The value of $\\chi^{(2)}$ is enhanced\nup to 200 pm/V which is promising a strong Second Harmonic Generation (SHG) in\nSiNWs. For [100], [110] and [111] SiNWs, yxx component of $\\chi^{(2)}$ tensor\nis 81, 225 and 81 pm/V, respectively. These are in close agreement with\n$\\chi^{(2)}$ values reported for strained silicon waveguides in experiments.\nThe 3rd order susceptibility, $\\chi^{(3)}$, is within the range of\n(0.1-12)x$10^{-18} \\frac{m^{2}}{V^{2}}$ which is close to the experimental\nvalues of bulk silicon (0.1-0.2)x$10^{-18} \\frac{m^{2}}{V^{2}}$ for [110] and\n[100] SiNWs and it is 100 times better for [111] SiNW. This study suggests\npossibilities of enhancing SHG in SiNWs through symmetry breaking via strain\nand surface termination/reconstruction as well as suitability of this DFT-based\nmethod in predicting nonlinear optical susceptibilities of nano structures."
    },
    {
        "anchor": "Nanoparticle enhanced evaporation of liquids: A case study of silicone\n  oil and water: Evaporation is a fundamental physical phenomenon, of which many challenging\nquestions remain unanswered. Enhanced evaporation of liquids in some occasions\nis of enormous practical significance. Here we report the enhanced evaporation\nof the nearly permanently stable silicone oil by dispersing with nanopariticles\nincluding CaTiO3, anatase and rutile TiO2. The results can inspire the research\nof atomistic mechanism for nanoparticle enhanced evaporation and exploration of\nevaporation control techniques for treatment of oil pollution and restoration\nof dirty water.",
        "positive": "Optically driven ultrafast magnetic order transitions in two-dimensional\n  ferrimagnets: Laser-induced switching and manipulation of the spins in magnetic materials\nare of great interest to revolutionize future magnetic storage technology and\nspintronics with fastest speed and least power dissipative. Inspired by the\nrecent discovery of intrinsic two-dimensional (2D) magnets, which provide\nunique platform to explore the new phenomenon for light-control magnetism in\nthe 2D limit, we propose to realize light can efficiently tune magnetic\nproperties of 2D ferrimagnets in early time. Here, using the 2D ferrimagnetic\nMXenes as prototype systems, our real-time density functional theory (TDDFT)\nsimulation show that laser pulses can directly induce ultrafast spin-selective\ncharge transfer between two magnetic sublattices on a few femtoseconds, and\nfurther generate dramatic changes in the magnetic structure of these MXenes,\nincluding a magnetic order transition from ferrimagnetic (FiM) to transient\nferromagnetic (FM). The microscopic mechanism underpinning this ultrafast\nswitching of magnetic order in MXenes is governed by optically induced\ninter-site spin transfer (OISTR) effect, which theoretically enables the\nultrafast direct optical manipulation of the magnetic state in MXenes-based\nmaterials. Our results open new opportunities to optically manipulate the spin\nin 2D magnets."
    },
    {
        "anchor": "Gate control of low-temperature spin dynamics in two-dimensional hole\n  systems: We have investigated spin and carrier dynamics of resident holes in\nhigh-mobility two-dimensional hole systems in GaAs/Al$_{0.3}$Ga$_{0.7}$As\nsingle quantum wells at temperatures down to 400 mK. Time-resolved Faraday and\nKerr rotation, as well as time-resolved photoluminescence spectroscopy are\nutilized in our study. We observe long-lived hole spin dynamics that are\nstrongly temperature dependent, indicating that in-plane localization is\ncrucial for hole spin coherence. By applying a gate voltage, we are able to\ntune the observed hole g factor by more than 50 percent. Calculations of the\nhole g tensor as a function of the applied bias show excellent agreement with\nour experimental findings.",
        "positive": "Quantum Kinetic Theory of the Chiral Anomaly: We present a general quantum kinetic theory of low-field magnetotransport in\nweakly disordered crystals that accounts fully for the interplay between\nelectric-field induced interband coherence, Bloch-state scattering, and an\nexternal magnetic field. The quantum kinetic equation we derive for the\nBloch-state density matrix naturally incorporates the momentum-space Berry\nphase effects whose influence on Bloch-state wavepacket dynamics is normally\nincorporated into transport theory in an ad hoc manner. The Berry phase\ncorrection to the momentum-space density of states in the presence of an\nexternal magnetic field implied by semiclassical wavepacket dynamics is\ncaptured by our theory as an intrinsic density-matrix response to a magnetic\nfield. We propose a simple and general procedure for expanding the linear\nresponse of the Bloch-state density matrix to an electric field in powers of\nmagnetic field. As an illustration, we apply our theory to magnetotransport in\nWeyl semimetals. We show that the chiral anomaly (positive magnetoconductivity\nquadratic in magnetic field) that appears when separate Fermi surface pockets\nsurround distinct Weyl points survives only when intervalley scattering is very\nweak compared to intravalley scattering."
    },
    {
        "anchor": "Spontaneous time-reversal symmetry breaking in twisted double bilayer\n  graphene: Twisted double bilayer graphene (tDBG) comprises two Bernal-stacked bilayer\ngraphene sheets with a twist between them. Gate voltages applied to top and\nback gates of a tDBG device tune both the flatness and topology of the\nelectronic bands, enabling an unusual level of experimental control. Broken\nspin/valley symmetry metallic states have been observed in tDBG devices with\ntwist angles $\\sim $ 1.2-1.3$^\\circ$, but the topologies and order parameters\nof these states have remained unclear. We report the observation of an\nanomalous Hall effect in the correlated metal state of tDBG, with hysteresis\nloops spanning 100s of mT in out-of-plane magnetic field ($B_{\\perp}$) that\ndemonstrate spontaneously broken time-reversal symmetry. The $B_{\\perp}$\nhysteresis persists for in-plane fields up to several Tesla, suggesting valley\n(orbital) ferromagnetism. At the same time, the resistivity is strongly\naffected by even mT-scale values of in-plane magnetic field, pointing to\nspin-valley coupling or to a direct orbital coupling between in-plane field and\nthe valley degree of freedom.",
        "positive": "Charge localisation on a redox-active single molecule junction and its\n  influence on coherent electron transport: For adjusting the charging state of a molecular metal complex in the context\nof a density functional theory description of coherent electron transport\nthrough single molecule junctions, we correct for self interaction effects by\nfixing the charge on a counterion, which in our calculations mimics the effect\nof the gate in an electrochemical STM setup, with two competing methods, namely\nthe generalized $\\Delta$ SCF technique and screening with solvation shells. One\nwould expect a transmission peak to be pinned at the Fermi energy for a nominal\ncharge of +1 on the molecule in the junction but we find a more complex\nsituation in this multicomponent system defined by the complex, the leads, the\ncounterion and the solvent. In particular equilibrium charge transfer between\nthe molecule and the leads plays an importanty role, which we investigate in\ndependence on the total external charge in the context of electronegativity\ntheory."
    },
    {
        "anchor": "Current flow paths in deformed graphene: from quantum transport to\n  classical trajectories in curved space: In this work we compare two fundamentally different approaches to the\nelectronic transport in deformed graphene: a) the condensed matter approach in\nwhich current flow paths are obtained by applying the non-equilibrium Green's\nfunction (NEGF) method to the tight-binding model with local strain, b) the\ngeneral relativistic approach in which classical trajectories of relativistic\npoint particles moving in a curved surface with a pseudo-magnetic field are\ncalculated. The connection between the two is established in the long-wave\nlimit via an effective Dirac Hamiltonian in curved space. Geometrical optics\napproximation, applied to focused current beams, allows us to directly compare\nthe wave and the particle pictures. We obtain very good numerical agreement\nbetween the quantum and the classical approaches for a fairly wide set of\nparameters, improving with the increasing size of the system. The presented\nmethod offers an enormous reduction of complexity from irregular tight-binding\nHamiltonians defined on large lattices to geometric language for curved\ncontinuous surfaces. It facilitates a comfortable and efficient tool for\npredicting electronic transport properties in graphene nanostructures with\ncomplicated geometries. Combination of the curvature and the pseudo-magnetic\nfield paves the way to new interesting transport phenomena such as bending or\nfocusing (lensing) of currents depending on the shape of the deformation. It\ncan be applied in designing ultrasensitive sensors or in nanoelectronics.",
        "positive": "Dimensional crossover in quantum networks: from macroscopic to\n  mesoscopic Physics: We report on magnetoconductance measurements of metallic networks of various\nsizes ranging from 10 to $10^{6}$ plaquettes, with anisotropic aspect ratio.\nBoth Altshuler-Aronov-Spivak (AAS) $h/2e$ periodic oscillations and\nAharonov-Bohm (AB) $h/e$ periodic oscillations are observed for all networks.\nFor large samples, the amplitude of both oscillations results from the\nincoherent superposition of contributions of phase coherent regions. When the\ntransverse size becomes smaller than the phase coherent length $L_\\phi$, one\nenters a new regime which is phase coherent (mesoscopic) along one direction\nand macroscopic along the other, leading to a new size dependence of the\nquantum oscillations."
    },
    {
        "anchor": "Thermoelectric transport with electron-phonon coupling and\n  electron-electron interaction in molecular junctions: Within the framework of nonequilibrium Green's functions, we investigate the\nthermoelectric transport in a single molecular junction with electron-phonon\nand electron-electron interactions. By transforming into a displaced phonon\nbasis, we are able to deal with these interactions non-perturbatively. Then, by\ninvoking the weak tunneling limit, we are able to calculate the\nthermoelectricity. Results show that at low temperatures, resonances of the\nthermoelectric figure of merit ZT occur around the sides of resonances of\nelectronic conductance but drops dramatically to zero at exactly these resonant\npoints. We find ZT can be enhanced by increasing electron-phonon coupling and\nCoulomb repulsion, and an optimal enhancement is obtained when these two\ninteractions are competing. Our results indicate a great potential for\nsingle-molecular-junctions as good thermoelectric devices over a wide range of\ntemperatures.",
        "positive": "Novel behaviors of monolayer quantum gases on Graphene, Graphane and\n  Fluorographene: This article discusses the behavior of submonolayer quantum films (He and H2)\non graphene and newly discovered surfaces that are derived from graphene. Among\nthese substrates are graphane (abbreviated GH), which has an H atom bonded to\neach C atom, and fluorographene (GF). For the graphite case, extensive\nexperimental and theoretical investigations have revealed that the phase\ndiagrams of the bose gases 4He and para-H2 are qualitatively similar, differing\nprimarily in a higher characteristic temperature scale for H2 than for He. The\nphase behaviors of these films on one side of pristine graphene, or both sides\nof free-standing graphene, are expected to be similar to those on graphite. We\npoint out the possibility of novel phenomena in adsorption on graphene related\nto the large flexibility of the graphene sheet, to the non--negligible\ninteraction between atoms adsorbed on opposite sides of the sheet and to the\nperturbation effect of the adsorbed layer on the Dirac electrons. In contrast,\nthe behaviors predicted on GF and GH surfaces are very different from those on\ngraphite, a result of the different corrugation, i.e., the lateral variation of\nthe potential experienced by these gases. As a result of this novel geometry\nand potential, distinct properties are observed. For example, the 4He film's\nground-state on graphite is a two-dimensional (2D) crystal commensurate with\nthe substrate; on GF and GH, instead, it is predicted to be an anisotropic\nsuperfluid. On GF the anisotropy is so extreme that the roton excitations are\nvery anisotropic, as if the bosons are moving in a multiconnected space along\nthe bonds of a honeycomb lattice. Such a novel phase has not been predicted or\nobserved previously on any substrate. Also, in the case of 3He the film's\nground-state is a fluid, thus offering the possibility of studying an\nanisotropic Fermi fluid with a tunable density."
    },
    {
        "anchor": "Molecule States in a Gate Tunable Graphene Double Quantum Dot: We have measured a graphene double quantum dot device with multiple\nelectrostatic gates that are used to enhance control to investigate it. At low\ntemperatures the transport measurements reveal honeycomb charge stability\ndiagrams which can be tuned from weak to strong interdot tunnel coupling\nregimes. We precisely extract a large interdot tunnel coupling strength for\nthis system allowing for the observation of tunnel-coupled molecular states\nextending over the whole double dot. This clean, highly controllable system\nserves as an essential building block for quantum devices in a\nnuclear-spin-free world.",
        "positive": "Exploring self-consistency of the equations of axion electrodynamics in\n  Weyl semimetals: Recent works have provided evidence that an axial anomaly can arise in Weyl\nsemimetals. If this is the case, then the electromagnetic response of Weyl\nsemimetals should be governed by the equations of axion electrodynamics. These\nequations capture both the chiral magnetic and anomalous Hall effects in the\nlimit of linear response, while at higher orders their solutions can provide\ndetectable electromagnetic signatures of the anomaly. In this work, we consider\nthree versions of axion electrodynamics that have been proposed in the Weyl\nsemimetal literature. These versions differ in the form of the chiral magnetic\nterm and in whether or not the axion is treated as a dynamical field. In each\ncase, we look for solutions to these equations for simple sample geometries\nsubject to applied external fields. We find that in the case of a linear chiral\nmagnetic term generated by a non-dynamical axion, self-consistent solutions can\ngenerally be obtained. In this case, the magnetic field inside of the Weyl\nsemimetal can be magnified significantly, providing a testable signature for\nexperiments. Self-consistent solutions can also be obtained for dynamical\naxions, but only in cases where the chiral magnetic term vanishes identically.\nFinally, for a nonlinear form of the chiral magnetic term frequently considered\nin the literature, we find that there are no self-consistent solutions aside\nfrom a few special cases."
    },
    {
        "anchor": "Quasiparticle Energies and Band Gaps of Graphene Nanoribbons: We present calculations of the quasiparticle energies and band gaps of\ngraphene nanoribbons (GNRs) carried out using a first-principles many-electron\nGreen's function approach within the GW approximation. Because of the\nquasi-one-dimension nature of a GNR, electron-electron interaction effects due\nto the enhanced screened Coulomb interaction and confinement geometry greatly\ninfluence the quasiparticle band gap. Compared with previous tight-binding and\ndensity functional theory studies, our calculated quasiparticle band gaps show\nsignificant self-energy corrections for both armchair and zigzag GNRs, in the\nrange of 0.5-3.0 eV for ribbons of width 2.4-0.4 nm. The quasiparticle band\ngaps found here suggest that use of GNRs for electronic device components in\nambient conditions may be viable.",
        "positive": "Efficient and Reversible CO2 Capture by Lithium-functionalized Germanene\n  Monolayer: First-principles density functional theory (DFT) is employed to investigate\nthe interactions of CO2 gas molecules with pristine and lithium-functionalized\ngermanene. It is discovered that although a single CO2 molecule is weakly\nphysisorbed on pristine germanene, a significant improvement on its adsorption\nenergy is found by utilizing Li-functionalized germanene as the adsorbent.\nHowever, the moderate adsorption energy at high CO2 coverage predicts an easy\nrelease step. More excitingly, the structure of Li-functionalized germanene can\nbe fully recovered after removal of CO2 gas molecules. Our results suggest that\nLi-functionalized germanene show promise for CO2 sensing and capture with a\nstorage capacity of 12.57 mol/kg."
    },
    {
        "anchor": "Devil's staircase, spontaneous-DC bias, and chaos via quasiperiodic\n  plasma oscillations in semiconductor superlattices: We study a plasma instability in semiconductor superlattices irradiated by a\nmonochromatic, pure AC electric field. The instability leads to sustained\noscillations at a frequency \\omega 2 that is either incommensurate to the\ndrive, or frequency-locked to it, \\omega 2 = (p/q) \\omega. A spontaneously\ngenerated DC bias is found when either p or q in the locking ratio are even\nintegers. Frequency locked regions form Arnol'd tongues in parameter space and\nthe ratio \\omega 2 / \\omega\\ exhibits a Devil's staircase. A transition to\nchaotic motion is observed as resonances overlap.",
        "positive": "Dimensionality driven charge density wave instability in TiS$_2$: Density functional theory and density functional perturbation theory are used\nto investigate the electronic and vibrational properties of TiS$_2$. Within the\nlocal density approximation the material is a semi-metal both in the bulk and\nin the monolayer form. Most interestingly we observe a Kohn anomaly in the bulk\nphonon dispersion, which turns into a charge density wave instability when\nTiS$_2$ is thinned to less than four monolayers. Such charge density wave phase\ncan be tuned by compressive strain, which appears to be the control parameter\nof the instability."
    },
    {
        "anchor": "Electron-phonon interaction on the surface of a 3D topological insulator: We analyze the role of a Rayleigh surface phonon mode in the electron-phonon\ninteraction at the surface of a 3D topological insulator. A strong\nrenormalization of the phonon dispersion, leading eventually to the\ndisappearance of Rayleigh phonons, is ruled out in the ideal case of a\ncontinuum long-wavelength limit, which is only justified if the surface is\nclean and defect free. The absence of backscattering for Dirac electrons at the\nFermi surface is partly responsible for the reduced influence of the\nelectron-phonon interaction. A pole in the dielectric response function due to\nthe Rayleigh phonon dispersion could drive the electron-electron interaction\nattractive at low frequencies. However, the average pairing interaction within\nthe weak coupling approach is found to be too small to induce a surface\nsuperconducting instability.",
        "positive": "Particle-continuum-medium duality of skyrmions: Topological solitons are crucial to many branches of physics, such as models\nof fundamental particles in quantum field theory, information carriers in\nnonlinear optics, and elementary entities in quantum and classical\ncomputations. Chiral magnetic materials are a fertile ground for studying\nsolitons. In the past a few years, a huge number of all kinds of topologically\nprotected localized magnetic solitons have been found. The number is so large,\nand a proper organization and classification is necessary for their future\ndevelopments. Here we show that many topological magnetic solitons can be\nunderstood from the duality of particle and elastic continuum-medium nature of\nskyrmions. In contrast to the common belief that a skyrmion is an elementary\nparticle that is indivisible, skyrmions behave like both particle and continuum\nmedia that can be tore apart to bury other objects, reminiscing particle-wave\nduality in quantum mechanics. Skyrmions, like indivisible particles, can be\nbuilding blocks for cascade skyrmion bags and target skyrmions. They can also\nact as bags and glues to hold one or more skyrmions together. The principles\nand rules for stable composite skyrmions are explained and presented, revealing\ntheir rich and interesting physics."
    },
    {
        "anchor": "Fundamental description of Wannier qubits of any topology in\n  semiconductor by analytical and numerical computations: Justification of tight-binding model from Schroedinger formalism for various\ntopologies of position-based semiconductor qubits is presented in this work.\nSimplistic tight-binding model allows for description of single-electron\ndevices at large integration scale. However it is due to the fact that\ntight-binding model omits the integro-differential equations that arise from\nelectron-electron interaction in Schroedinger model. Two approaches are given\nin derivation of tight-binding model from Schroedinger equation. First approach\nis conducted by usage of Green functions obtained from Schroedinger equation.\nSecond approach is given by usage of Taylor expansion applied to Schroedinger\nequation. The obtained results can be extended for the case of many Wannier\nqubits with more than one electron and can be applied to 2 and 3 dimensional\nmodel. Furthermore various correlation functions are proposed in Schroedinger\nformalism that can account for static and time-dependent electric and magnetic\nfield polarizing given Wannier qubit system. One of the central results of\npresented work relies on the emergence of dissipation processes during smooth\nbending of semiconductor nanowires both in the case of classical and quantum\npicture. Presented results give the base for physical description of\nelectrostatic Q-Swap gate of any topology using open loop nanowires. We observe\nstrong localization of wavepacket due to nanowire bending.",
        "positive": "Stable structures and electronic properties of perovskite oxide\n  monolayers: It is highly desirable to search for promising two-dimensional (2D) monolayer\nmaterials for deep insight of 2D materials and applications. We use\nfirst-principles method to investigate tetragonal perovskite oxide monolayers\nas 2D materials. We find four stable 2D monolayer materials from SrTiO$_3$,\nLaAlO$_3$, KTaO$_3$, and BaFeO$_3$, denoting them as STO-ML, LAO-ML, KTO-ML,\nand BFO-ML. Our further study shows that through overcoming dangling bonds the\nfirst three monolayers are 2D wide-gap semiconducotors, and BFO-ML is a 2D\nisotropic Heisenberg ferromagnetic metal. There is a large electrostatic\npotential energy difference between the two sides, reflecting a large\nout-of-plane dipole, in each of the monolayers. These make a series of 2D\nmonolayer materials, and should be useful in novel electronic devices\nconsidering emerging phenomena in perovskite oxide heterostructures."
    },
    {
        "anchor": "Shot Noise with Interaction Effects in Single Walled Carbon Nanotubes: We have measured shot noise in single walled carbon nanotubes (SWNT) with\ngood contacts at 4.2 K at low frequencies ($f=600 - 850$ MHz). We find a strong\nmodulation of shot noise over the Fabry-Perot pattern; in terms of differential\nFano factor the variation ranges over 0.4 - 1.2. The shot noise variation, in\ncombination with differential conductance, is analyzed using two\n(spin-degenerate) modes with different, energy-dependent transmission\ncoefficients. No power law dependence of shot noise, as expected for Luttinger\nliquids, was found in our measurements.",
        "positive": "Decoherence induced by electron accumulation in quantum measurement of\n  charge qubits: In this paper, we study the quantum decoherence induced by accumulation of\nelectron tunnelings during the quantum measurement of a charge qubit. The\ncharge qubit is a single electron confined in coupled quantum dots. The\nmeasurement of the qubit states is performed using a quantum point contact. A\nset of master equations for qubit states is derived within a nonequilibrium\nperturbation to the equilibrium reservoir due to the electron accumulation\nbetween the source and drain of the quantum point contact. The quantum\ndecoherence of the qubit states arose from the electron accumulation during the\nmeasurement is explored in this framework, and several interesting results on\ncharge qubit decoherence are obtained."
    },
    {
        "anchor": "Single-color pyrometry of individual incandescent multiwalled carbon\n  nanotubes: Objects that are small compared to their thermal photon wavelengths violate\nthe assumptions underlying optical pyrometry and can show unusual coherence\neffects. To investigate this regime we measure the absolute light intensity\nfrom individual, incandescent multiwalled carbon nanotubes. The nanotube\nfilaments' physical dimensions and composition are determined using\ntransmission electron microscopy and their emissivities are calculated in terms\nof bulk conductivities. A single-color pyrometric analysis then returns a\ntemperature value for each wavelength, polarization, and applied bias measured.\nCompared to the more common multiwavelength analysis, single-color pyrometry\nsupports a more consistent and complete picture of the carbon nanotube lamps,\none that describes their emissivity, optical conductivity, and thermal\nconductivity in the range 1600-2400 K.",
        "positive": "Magnetothermopower and magnon-assisted transport in ferromagnetic tunnel\n  junctions: We present a model of the thermopower in a mesoscopic tunnel junction between\ntwo ferromagnetic metals based upon magnon-assisted tunneling processes. In our\nmodel, the thermopower is generated in the course of thermal equilibration\nbetween two baths of magnons, mediated by electrons. We predict a particularly\nlarge thermopower effect in the case of a junction between two half-metallic\nferromagnets with antiparallel polarizations, $S_{AP} \\sim - (k_B/e)$, in\ncontrast to $S_{P} \\approx 0$ for a parallel configuration."
    },
    {
        "anchor": "Floquet Majorana Fermions for Topological Qubits: We introduce and develop an approach to realizing a topological phase\ntransition and non-Abelian statistics with dynamically induced Floquet Majorana\nFermions (FMFs). When the periodic driving potential does not break fermion\nparity conservation, FMFs can encode quantum information. Quasi-energy analysis\nshows that a stable FMF zero mode and two other satellite modes exist in a wide\nparameter space with large quasi-energy gaps, which prevents transitions to\nother Floquet states under adiabatic driving. We also show that in the\nasymptotic limit FMFs preserve non-Abelian statistics and, thus, behave like\ntheir equilibrium counterparts.",
        "positive": "Polariton lasing in high-quality Selenide-based micropillars in the\n  strong coupling regime: We have designed and fabricated all-epitaxial ZnSe-based optical micropillars\nexhibiting the strong coupling regime between the excitonic transition and the\nconfined optical cavity modes. At cryogenic temperatures, under non-resonant\npulsed optical excitation, we demonstrate single transverse mode polariton\nlasing operation in the micropillars. Owing to the high quality factors of\nthese microstructures, the lasing threshold remains low even in micropillars of\nthe smallest diameter. We show that this feature can be traced back to a\nsidewall roughness grain size below 3 nm, and to suppressed in-plane polariton\nescape."
    },
    {
        "anchor": "Alternating twisted mutilayer graphene: generic partition rules, double\n  flat bands, and orbital magnetoelectric effect: Twisted graphene systems have draw significant attention due to the\ndiscoveries of various correlated and topological phases. In particular,\nrecently the alternating twisted trilayer graphene is discovered to exhibit\nunconventional superconductivity, which motivates us to study the electronic\nstructures and possible interesting correlation effects of this class of\nalternating twisted graphene systems. In this work we consider generic\nalternating twisted multilayer graphene (ATMG) systems with $M$-$L$-$N$\nstacking configurations, in which the $M$ ($L$) graphene layers and the $L$\n($N$) layers are twisted by an angle $\\theta$ (-$\\theta$). Based on analysis\nfrom a simplified $\\textbf{k}\\!\\cdot\\!\\textbf{p}$ model approach, we\nanalytically derive generic partition rules for the low-energy electronic\nstructures, which exhibit various intriguing band dispersions including one\npair of flat bands, two pairs of flat bands, as well as flat bands co-existing\nwith with Dirac cones, quadratic bands, or more generally\n$E(\\mathbf{k})\\!\\sim\\!k^J$ dispersions ($J$ is positive integer) for each spin\nand valley. Such unusual non-interacting electronic structures may have\nunconventional correlation effects. Especially for a mirror symmetric ATMG\nsystem with two pairs of flat bands (per spin per valley), we find that Coulomb\ninteractions may drive the system into a state breaking both time-reversal and\nmirror symmetries, which can exhibit a novel type of orbital magnetoelectric\neffect due to the interwining of electric polarization and orbital\nmagnetization orders in the symmetry-breaking state.",
        "positive": "Twist-angle engineering of excitonic quantum interference and optical\n  nonlinearities in stacked 2D semiconductors: Twist-engineering of the electronic structure of van-der-Waals layered\nmaterials relies predominantly on band hybridization between layers. Band-edge\nstates in transition-metal-dichalcogenide semiconductors are localized around\nthe metal atoms at the center of the three-atom layer and are therefore not\nparticularly susceptible to twisting. Here, we report that high-lying excitons\nin bilayer WSe2 can be tuned over 235 meV by twisting, with a twist-angle\nsusceptibility of 8.1 meV/{\\deg}, an order of magnitude larger than that of the\nband-edge A-exciton. This tunability arises because the electronic states\nassociated with upper conduction bands delocalize into the chalcogenide atoms.\nThe effect gives control over excitonic quantum interference, revealed in\nselective activation and deactivation of electromagnetically induced\ntransparency (EIT) in second-harmonic generation. Such a degree of freedom does\nnot exist in conventional dilute atomic-gas systems, where EIT was originally\nestablished, and allows us to shape the frequency dependence, i.e. the\ndispersion, of the optical nonlinearity."
    },
    {
        "anchor": "Modeling of diffusion of injected electron spins in spin-orbit coupled\n  microchannels: We report on a theoretical study of spin dynamics of an ensemble of\nspin-polarized electrons injected in a diffusive microchannel with linear\nRashba and Dresselhaus spin-orbit coupling. We explore the dependence of the\nspin-precession and spin-diffusion lengths on the strengths of spin-orbit\ninteraction and external magnetic fields, microchannel width, and orientation.\nOur results are based on numerical Monte Carlo simulations and on approximate\nanalytical formulas, both treating the spin dynamics quantum-mechanically. We\nconclude that spin-diffusion lengths comparable or larger than the\nprecession-length occur i) in the vicinity of the persistent spin helix regime\nfor arbitrary channel width, and ii) in channels of similar or smaller width\nthan the precession length, independent of the ratio of Rashba and Dresselhaus\nfields. For similar strengths of the Rashba and Dresselhaus fields, the\nsteady-state spin-density oscillates or remains constant along the channel for\nchannels parallel to the in-plane diagonal crystal directions. An oscillatory\nspin-polarization pattern tilted by 45$^{\\circ}$ with respect to the channel\naxis is predicted for channels along the main cubic crystal directions. For\ntypical experimental system parameters, magnetic fields of the order of Tesla\nare required to affect the spin-diffusion and spin-precession lengths.",
        "positive": "Performance Analysis of a Near-Field Thermophotovoltaic Device with a\n  Metallodielectric Selective Emitter and Electrical Contacts for the\n  Photovoltaic Cell: A near-field thermophotovoltaic (TPV) system with a multilayer emitter of\nalternate tungsten and alumina layer is proposed in this paper. The\nfluctuational electrodynamics along with the dyadic Green function for a\nmultilayered structure is applied to calculate the spectral heat flux, and the\ncharge transport equations are solved to get the photocurrent generation and\nelectrical power output. The spectral heat flux is much enhanced when plain\ntungsten emitter is replaced with multilayer emitter. The mechanism of surface\nplasmon polariton coupling in the tungsten thin film, which is responsible for\nthe heat flux enhancement, is analyzed. In addition, the invalidity of\neffective medium theory to predict the optical properties of multilayer\nstructure in near-field radiation is discussed. The tungsten and alumina layer\nthicknesses are optimized to match the spectral heat flux with the bandgap of\nTPV cell. Practically, with a gold reflector placed on the back of TPV cell,\nwhich also acts as the back electrode, and a 5-nm-thick indium tin oxide (ITO)\nlayer as the front contact, when the emitter and receiver temperature are\nrespectively set as 2000 K and 300 K, the conversion efficiency and electrical\npower output can be achieved to 23.7% and 0.31 MW/m2 at a vacuum gap distance\nof 100 nm."
    },
    {
        "anchor": "Realizing Wide Bandgap P-SiC-emitter Lateral Heterojunction Bipolar\n  Transistors with low collectoremitter offset voltage and high current gain -\n  A novel proposal using numerical simulation: We report a novel method to reduce the collector-emitter offset-voltage of\nthe wide bandgap SiC-P-emitter lateral HBTs using a dual-bandgap emitter. In\nour approach, the collector-emitter offset-voltage VCE(offset) is reduced\ndrastically by eliminating the built-in potential difference between the\nemitter-base (EB) junction and collector-base (CB) junction by using a\nSiC-on-Si P-emitter. We demonstrate that the proposed dualbandgap P-emitter HBT\ntogether with the SiGe base and Schottky collector, not only has a very low\nVCE(offset) but also exhibits high current gain, reduced Kirk effect, excellent\ntransient response and high cutoff frequency. We evaluated the performance of\nthe proposed device in detail using two dimensional device simulation and a\npossible BiCMOS compatible fabrication procedure is also suggested.",
        "positive": "A computational mean-field model of interacting non-collinear classical\n  spins: Mean-field approximation is often used to explore the qualitative behaviour\nof phase transitions in classical spin models before employing computationally\ncostly methods such as the Monte-Carlo techniques. We implement a 'lattice\nsite-resolved' mean-field spin model that allows efficient simulation of phase\ntransitions between phases of complex magnetic domains, such as magnetic\nhelices, skyrmions, or states with canted spins. The framework is useful as a\ncomplementary approach for pre-screening the qualitative features of phase\ndiagrams in complex magnets."
    },
    {
        "anchor": "Giant terahertz photoconductance of tunneling point contacts: We report on the observation of the giant photoconductance of a quantum point\ncontact (QPC) in tunneling regime excited by terahertz radiation. Studied QPCs\nare formed in a GaAs/AlGaAs heterostructure with a high-electron-mobility\ntwo-dimensional electron gas. We demonstrate that irradiation of strongly\nnegatively biased QPCs by laser radiation with frequency f = 0.69 THz and\nintensity 50 mW/cm^2 results in two orders of magnitude enhancement of the QPC\nconductance. The effect has a superlinear intensity dependence and increases\nwith the dark conductivity decrease. It is also characterized by strong\npolarization and frequency dependencies. We demonstrate that all experimental\nfindings can be well explained by the photon-mediated tunneling through the\nQPC. Corresponding calculations are in a good agreement with the experiment.",
        "positive": "Suppression of nuclear spin fluctuations in an InGaAs quantum dot\n  ensemble by GHz-pulsed optical excitation: The coherent electron spin dynamics of an ensemble of singly charged\n(In,Ga)As/GaAs quantum dots in a transverse magnetic field is driven by\nperiodic optical excitation at 1 GHz repetition frequency. Despite the strong\ninhomogeneity of the electron $g$ factor, the spectral spread of optical\ntransitions, and the broad distribution of nuclear spin fluctuations, we are\nable to push the whole ensemble of excited spins into a single Larmor\nprecession mode that is commensurate with the laser repetition frequency.\nFurthermore, we demonstrate that an optical detuning of the pump pulses from\nthe probed optical transitions induces a directed dynamic nuclear polarization\nand leads to a discretization of the total magnetic field acting on the\nelectron ensemble. Finally, we show that the highly periodic optical excitation\ncan be used as universal tool for strongly reducing the nuclear spin\nfluctuations and preparation of a robust nuclear environment for subsequent\nmanipulation of the electron spins, also at varying operation frequencies."
    },
    {
        "anchor": "Review of flexible and transparent thin-film transistors based on zinc\n  oxide and related materials: Flexible and transparent electronics presents a new era of electronic\ntechnologies. Ubiquitous applications involve wearable electronics, biosensors,\nflexible transparent displays, radio-frequency identifications (RFIDs),\netc.Zinc oxide (ZnO) and related materials are the most commonly used inorganic\nsemiconductors in flexible and transparent devices, owing to their high\nelectrical performance, together with low processing temperature and good\noptical transparency.In this paper, we review recent advances in flexible and\ntransparent thin-film transistors (TFTs) based on ZnO and related\nmaterials.After a brief introduction, the main progresses on the preparation of\neach component (substrate, electrodes, channel and dielectrics) are summarized\nand discussed. Then, the effect of mechanical bending on electrical performance\nwas highlighted. Finally, we suggest the challenges and opportunities in future\ninvestigations.",
        "positive": "Vanishing Hall Response of Charged Fermions in a Transverse Magnetic\n  Field: We study the Hall response of quasi-two-dimensional lattice systems of\ncharged fermions under a weak transverse magnetic field, in the ballistic\ncoherent limit. We identify a setup in which this response vanishes over a wide\nrange of parameters: the paradigmatic \"Landauer-B\\\"uttiker\" setup commonly\nstudied for coherent quantum transport, consisting of a strip contacted to\nbiased ideal reservoirs of charges. We show that the effect does not rely on\nparticle-hole symmetry, and is robust to a variety of perturbations including\nvariations of the transverse magnetic field, chemical potential, and\ntemperature. We trace this robustness back to a topological property of the\nFermi surface: the number of Fermi points (central charge) of the system. We\nargue that the mechanism responsible for the vanishing Hall response can\noperate both in noninteracting and interacting systems, which we verify in\nconcrete examples using density-matrix renormalization group (DMRG)\nsimulations."
    },
    {
        "anchor": "Surface plasmons in doped topological insulators: We investigate surface plasmons at a planar interface between a normal\ndielectric and a topological insulator, where the Fermi-energy lies inside the\nbulk gap of the topological insulator and gives rise to a two-dimensional\ncharge distribution of free Dirac electrons. We develop the methodology for the\ncalculation of plasmon dispersions, using the framework of classical\nelectrodynamics, with modified constituent equations due to Hall currents in\nthe topological insulator, together with a Lindhard-type description for the\ntwo-dimensional charge distribution of free Dirac electrons. For a system\nrepresentative for Bi$_2$X$_3$ binary compounds, we find in agreement with\nrecent related work that the modified constituent equations have practically no\nimpact on the surface plasmon dispersion but lead to a rotation of the magnetic\npolarization of surface plasmons out of the interface plane.",
        "positive": "Ultra-thin van der Waals crystals as semiconductor quantum wells: Control over the electronic spectrum at low energy is at the heart of the\nfunctioning of modern advanced electronics: high electron mobility transistors,\nsemiconductor and Capasso terahertz lasers, and many others. Most of those\ndevices rely on the meticulous engineering of the size quantization of\nelectrons in quantum wells. This avenue, however, hasn't been explored in the\ncase of 2D materials. Here we transfer this concept onto the van der Waals\nheterostructures which utilize few-layers films of InSe as quantum wells. The\nprecise control over the energy of the subbands and their uniformity guarantees\nextremely high quality of the electronic transport in such systems. Using novel\ntunnelling and light emitting devices, for the first time we reveal the full\nsubbands structure by studying resonance features in the tunnelling current,\nphotoabsorption and light emission. In the future, these systems will allow\ndevelopment of elementary blocks for atomically thin infrared and THz light\nsources based on intersubband optical transitions in few-layer films of van der\nWaals materials."
    },
    {
        "anchor": "Time-resolved charge detection in graphene quantum dots: We present real-time detection measurements of electron tunneling in a\ngraphene quantum dot. By counting single electron charging events on the dot,\nthe tunneling process in a graphene constriction and the role of localized\nstates are studied in detail. In the regime of low charge detector bias we see\nonly a single time-dependent process in the tunneling rate which can be modeled\nusing a Fermi-broadened energy distribution of the carriers in the lead. We\nfind a non-monotonic gate dependence of the tunneling coupling attributed to\nthe formation of localized states in the constriction. Increasing the detector\nbias above 2 mV results in an increase of the dot-lead transition rate related\nto back-action of the charge detector current on the dot.",
        "positive": "Vacancies in Graphene : Dirac Physics and Fractional Vacuum Charges: The study of vacancies in graphene is a topic of growing interest. A single\nvacancy induces a localized stable charge of order unity interacting with other\ncharges of the conductor through an unscreened Coulomb potential. It also\nbreaks the symmetry between the two triangular graphene sublattices hence\ninducing zero energy states at the Dirac points. Here we show the fractional\nand pseudo-scalar nature of this vacancy charge. A continuous Dirac model is\npresented which relates zero modes to vacuum fractional charge and to a parity\nanomaly. This relation constitutes an Index theorem and is achieved by using\nparticular chiral boundary conditions, which map the vacancy problem onto edge\nstate physics. Vacancies in graphene thus allow to realize prominent features\nof $2+1$ quantum electrodynamics but without coupling to a gauge field. This\nessential difference makes vacancy physics relatively easy to implement and an\ninteresting playground for topological switching."
    },
    {
        "anchor": "Enhanced photon-phonon coupling via dimerization in one-dimensional\n  optomechanical crystals: We show that dimerization of an optomechanical crystal lattice, which leads\nto folding of the band diagram, can couple flexural mechanical modes to optical\nfields within the unit cell via radiation pressure. When compared to currently\nrealized crystals, a substantial improvement in the coupling between photons\nand phonons is found. For experimental verification, we implement a dimerized\nlattice in a silicon optomechanical nanobeam cavity and measure a vacuum\ncoupling rate of $g_0/2\\pi=1.7MHz$ between an optical resonance at $\\lambda_{c}\n= 1545nm$ and a mechanical resonance at 1.14GHz.",
        "positive": "Renormalization of Optical Excitations in Molecules near a Metal Surface: The lowest electronic excitations of benzene and a set of donor-acceptor\nmolecular complexes are calculated for the gas phase and on the Al(111) surface\nusing the many-body Bethe-Salpeter equation (BSE). The energy of the\ncharge-transfer excitations obtained for the gas phase complexes are found to\nbe around 10% lower than the experimental values. When the molecules are placed\noutside the surface, the enhanced screening from the metal reduces the exciton\nbinding energies by several eVs and the transition energies by up to 1 eV\ndepending on the size of the transition-generated dipole. As a striking\nconsequence we find that close to the metal surface the optical gap of benzene\ncan exceed its quasiparticle gap. A classical image charge model for the\nscreened Coulomb interaction can account for all these effects which, on the\nother hand, are completely missed by standard time-dependent density functional\ntheory."
    },
    {
        "anchor": "Distortion blockade in classical nano-electromechanical resonator: We consider a single electron transistor where the central island can\noscillate. It has been shown that for weak coupling of the elastic and electric\ndegrees of freedom the position of the island fluctuates with a small variation\nof the current through the device. In this paper we consider the strong\ncoupling limit. We show that the system undergoes a static mechanical\ninstability that is responsible for the opening of a gap in the current voltage\ncharacteristics even at the degeneracy point. We provide an analytical\ndescription of the transition point. We also discuss how the mechanical nature\nof the suppression of the current can be probed experimentally by a slow\nmodulation of the gate voltage.",
        "positive": "Ferromagnetic and underscreened Kondo behavior in quantum dot arrays: We analyze the low energy properties of a device with $N+1$ quantum dots in a\nstar configuration. A central quantum dot is tunnel coupled to source and drain\nelectrodes and to $N$ quantum dots. Extending previous results for the $N=2$\ncase we show that, in the appropriate parameter regime, the low energy\nHamiltonian of the system is a ferromagnetic Kondo model for a $S=(N-1)/2$\nimpurity spin. For small enough interdot tunnel coupling, however, a two-stage\nKondo effect takes place as the temperature is decreased. The spin $1/2$ in the\ncentral quantum dot is Kondo screened first and at lower temperatures the\nantiferromagnetic coupling to the side coupled quantum dots leads to an\nunderscreened $S=N/2$ Kondo effect. We present numerical results for the\nthermodynamic and spectral properties of the system which show a singular\nbehavior at low temperatures and allow to characterize the different strongly\ncorrelated regimes of the device."
    },
    {
        "anchor": "Disorder and dephasing effect on electron transport through conjugated\n  molecular wires in molecular junctions: Understanding electron transport processes in molecular wires connected\nbetween contacts is a central focus in the field of molecular electronics.\nEspecially, the dephasing effect causing tunneling-to-hopping transition has\ngreat importance from both applicational and fundamental points of view. We\nanalyzed coherent and incoherent electron transmission through conjugated\nmolecular wires by means of density-functional tight-binding theory within the\nD'Amato-Pastawski model. Our approach can study explicitly the\nstructure/transport relationship in molecular junctions in a dephasing\nenvironmental condition using only single dephasing parameter. We investigated\nthe length dependence and the influence of thermal fluctuations on transport\nand reproduced the well-known tunneling-to-hopping transition. This approach\nwill be a powerful tool for the interpretation of recent conductance\nmeasurements of molecular wires.",
        "positive": "Random-Matrix Theory of Quantum Transport: This is a comprehensive review of the random-matrix approach to the theory of\nphase-coherent conduction in mesocopic systems. The theory is applied to a\nvariety of physical phenomena in quantum dots and disordered wires, including\nuniversal conductance fluctuations, weak localization, Coulomb blockade,\nsub-Poissonian shot noise, reflectionless tunneling into a superconductor, and\ngiant conductance oscillations in a Josephson junction."
    },
    {
        "anchor": "Stability and chaos of a driven nano-electromechanical Josephson\n  junction: We consider the motion of and Josephson current through a mechanically\noscillating superconducting island asymmetrically embedded in a Josephson\njunction. The electromechanical coupling is provided by distance dependent\ntunneling rates between the electrodes and the island. The system asymmetry,\nresulting from the geometrical configuration, leads, for weak coupling, to an\nequation of the mechanical motion that reduces to the well-known Duffing\nequation. At zero bias voltage the island motion is determined by the\nhomogenous Duffing equation that opens up two separate regions of solutions\ndepending on the superconducting phases. The island either moves under\ninfluence of an anharmonic single well potential, or is governed by a double\nwell potential that allows for off-center oscillations. Under applied bias\nvoltage the island equation of motion turns into a modified Duffing equation,\nwith time dependent coefficients, that demonstrate both quasi periodic and\nchaotic behavior.",
        "positive": "Inelastic quantum transport in superlattices: success and failure of the\n  Boltzmann equation: Electrical transport in semiconductor superlattices is studied within a fully\nself-consistent quantum transport model based on nonequilibrium Green\nfunctions, including phonon and impurity scattering. We compute both the drift\nvelocity-field relation and the momentum distribution function covering the\nwhole field range from linear response to negative differential conductivity.\nThe quantum results are compared with the respective results obtained from a\nMonte Carlo solution of the Boltzmann equation. Our analysis thus sets the\nlimits of validity for the semiclassical theory in a nonlinear transport\nsituation in the presence of inelastic scattering."
    },
    {
        "anchor": "Electronic transport and the related anomalous effects in silicene-like\n  hexagonal lattice: We investigate the anomalous effects due to the Berry correction and the\nconsiderable perturbations in the silicene-like hexagonal lattice system. The\nBerry curvature in periodic Bloch band system which related to the\nelectromagnetic field is explored, the induced transverse anomalous velocity\ngives rise to the intrinsic Hall conductivity (without the vertex correction)\nexpecially in the quantum anomalous Hall phase. The quantum anomalous Hall\neffect which related to the anomalous velocity term is detected, including the\nband avoided corssing effect and the generated special band gap. %{Enlarged\nGalilean symmetry of anyons and the Hall effect} The topological spin transport\nis affected by the Berry curvature %{Topological spin transport of a\nrelativistic electron} %{Anomalous direction for skyrmion bubble motion} and\nthe spin-current-induced Skyrmion spin texture motion is contrasted between the\nquantum spin Hall effect and quantum anomalous Hall effect. Since silicene\ninvolving the orbital degree of freedom, the orbital magnetic moment and\norbital magnetization contributes significantly to the electronic transport\nproperties of silicene %{Photoinduced quantum spin and valley Hall effects, and\norbital magnetization in monolayer MoS2} as explored in this article. We also\ninvestigate the electronic tunneling properties of silicene in Josephon\njunction with the electric-field-induced Rashba-coupling, the anomalous effect\ndue to the Berry phase is mentioned. Our results is meaningful to the\napplication of the spintronics and valleytronics base on the silicene-like\ntopological insulators.",
        "positive": "All-electrical detection of skyrmion lattice state and chiral surface\n  twists: We study the high-temperature phase diagram of the chiral magnetic insulator\nCu$_2$OSeO$_3$ by measuring the spin-Hall magnetoresistance (SMR) in a thin Pt\nelectrode. We find distinct changes in the phase and amplitude of the SMR\nsignal at critical lines separating different magnetic phases of bulk\nCu$_2$OSeO$_3$. The skyrmion lattice state appears as a strong dip in the SMR\nphase. A strong enhancement of the SMR amplitude is observed in the conical\nspiral state, which we explain by an additional symmetry-allowed contribution\nto the SMR present in non-collinear magnets. We demonstrate that the SMR can be\nused as an all-electrical probe of chiral surface twists and skyrmions in\nmagnetic insulators."
    },
    {
        "anchor": "Heat conductance oscillations in two weakly connected charge Kondo\n  circuits: We revisit a model describing Seebeck effect on a weak link between two\ncharge Kondo circuits, which has been proposed in the [Phys. Rev. B 97, 085403\n(2018)]. We calculate the thermoelectric coefficients in the perturbation\ntheory assuming smallness of the reflection amplitudes of the quantum point\ncontacts. We focus on the linear response equations for the heat conductance in\nthree different scenarios as: Fermi liquid vs Fermi liquid, Fermi liquid vs\nnon-Fermi liquid, nonFermi liquid vs non-Fermi liquid. The oscillations of the\nheat conductance as a function of the gate voltage of each quantum dot are\nanalysed in both Fermi liquid and non-Fermi liquid regimes. We discuss possible\nexperimental realizations of the model to observe the signatures of the\nnon-Fermi liquid behaviour in the heat conductance measurements.",
        "positive": "Topological responses from gapped Weyl points in 2D altermagnets: Altermagnetism combines aspects of both ferromagnetism and\nantiferromagnetism, breaking spin degeneracy while possessing no net\nmagnetization. In this work, we study the symmetry requirements for\ntopologically protected Weyl points in 2D altermagnets, involving bands with\nthe same spin quantum number. We classify all spin-wallpaper groups whose\nsymmetries protect 2D Weyl points and show that their nontrivial topology is\ncharactrized by a quantized $\\pi$-Berry phase. Representative electronic\ntight-binding and magnonic linear spin-wave models are constructed to\ninvestigate the unusual transport characteristics of these 2D Weyl points.\nDifferent mass terms, induced for example through strain or via coupling to\nlight or a substrate, gap out the Weyl points leading to emerging gapped\ntopological phases. Depending on the mass terms, these phases carry finite\nChern and/or spin Chern numbers and exhibit protected edge states as well as\nanomalous electronic and thermal Hall responses. We calculate these Hall\ncurrents for the different topological phases."
    },
    {
        "anchor": "Angstrofluidics: walking to the limit: Angstrom-scale fluidic channels are ubiquitous in nature, and play an\nimportant role in regulating cellular traffic, signaling, and responding to\nstimuli. Synthetic channels are now a reality with the emergence of several\ncutting-edge bottom-up and top-down fabrication methods. In particular, the use\nof atomically thin two dimensional (2D) materials and nanotubes as components\nto build fluidic conduits has pushed the limits of fabrication to the\nAngstrom-scale. Here, we provide an overview of the recent developments in the\nfabrication methods for nano- and angstrofluidic channels while categorizing\nthem on the basis of dimensionality (0D pores, 1D tubes, 2D slits), along with\nthe latest advances in measurement techniques. We discuss the ionic transport\ngoverned by various stimuli in these channels and draw comparison of ionic\nmobility, streaming and osmotic power, with varying pore sizes across all the\ndimensionalities. Towards the end of the review, we highlight the unique future\nopportunities in the development of smart ionic devices.",
        "positive": "Relaxation of Optically Excited Carriers in Graphene: We explore the relaxation of photo-excited graphene by solving a transient\nBoltzmann transport equation with electron-phonon (e-ph) and electron-electron\n(e-e) scattering. Simulations show that when the excited carriers are relaxed\nby e-ph scattering only, a population inversion can be achieved at energies\ndetermined by the photon energy. However, e-e scattering quickly thermalizes\nthe carrier energy distributions washing out the negative optical conductivity\npeaks. The relaxation rates and carrier multiplication effects are presented as\na function of photon energy and dielectric constant."
    },
    {
        "anchor": "Spontaneous parametric down-conversion induced by non-degenerate\n  three-wave mixing in a scanning MEMS micro mirror: Scanning micro-mirror actuators are silicon-based oscillatory\nmicro-electro-mechanical systems (MEMS). They enable laser distance\nmeasurements for automotive LIDAR applications as well as projection modules\nfor the consumer market. For MEMS applications, the geometric structure is\ntypically designed to serve a number of functional requirements. Most\nimportantly, the mode spectrum contains a single high-Q mode, the drive mode,\nwhich per design is expected to yield the only resonantly excited geometric\nmotion during operation. Yet here, we report on the observation of a resonant\nthree-mode excitation via a process known as spontaneous parametric\ndown-conversion. We show that this phenomenon, most extensively studied in the\nfield of nonlinear optics, originates from three-wave coupling induced by\ngeometric nonlinearities. In combination with further Duffing-type\nnonlinearities, the micro mirror displays a variety of nonlinear dynamical\nbehaviour ranging from stationary state bifurcations to dynamical instabilities\nobservable via amplitude modulations. We are able to explain and emulate all\nexperimental observations using a single fundamental model. In particular, our\nanalysis allows us to understand the conditions for the onset of three-wave\ndown-conversion which if not accounted for in the design of the MEMS structure,\ncan have drastic impact on its functionality even leading to fracture.",
        "positive": "Depth mapping of metallic nanowire polymer nanocomposites by scanning\n  dielectric microscopy: Polymer nanocomposite materials based on metallic nanowires are widely\ninvestigated as transparent and flexible electrodes or as stretchable\nconductors and dielectrics for biosensing. Here we show that Scanning\nDielectric Microscopy (SDM) can map the depth distribution of metallic\nnanowires within the nanocomposites in a non-destructive way. This is achieved\nby a quantitative analysis of sub-surface electrostatic force microscopy\nmeasurements with finite-element numerical calculations. As an application we\ndetermined the three-dimensional spatial distribution of around 50 nm diameter\nsilver nanowires in 100 - 250 nm thick gelatin films. The characterization is\ndone both under dry ambient conditions, where gelatin shows a relatively low\ndielectric constant, epsilon around 5, and under humid ambient conditions,\nwhere its dielectric constant increases up to epsilon around 14. The present\nresults show that SDM can be a valuable non-destructive subsurface\ncharacterization technique for nanowire-based nanocomposite materials, which\ncan contribute to the optimization of these materials for applications in\nfields such as wearable electronics, solar cell technologies or printable\nelectronics."
    },
    {
        "anchor": "Classification of crystalline insulators without symmetry indicators:\n  atomic and fragile topological phases in twofold rotation symmetric systems: Topological crystalline phases in electronic structures can be generally\nclassified using the spatial symmetry characters of the valence bands and\nmapping them onto appropriate symmetry indicators. These mappings have been\nrecently applied to identify thousands of topological electronic materials.\nThere can exist, however, topological crystalline non-trivial phases that go\nbeyond this paradigm: they cannot be identified using spatial symmetry labels\nand consequently lack any classification. In this work, we achieve the first of\nsuch classifications showcasing the paradigmatic example of two-dimensional\ncrystals with twofold rotation symmetry. We classify the gapped phases in\ntime-reversal invariant systems with strong spin-orbit coupling identifying a\nset of three $\\mathbb{Z}_2$ topological invariants, which correspond to nested\nquantized partial Berry phases. By further isolating the set of atomic\ninsulators representable in terms of exponentially localized symmetric Wannier\nfunctions, we infer the existence of topological crystalline phases of the\nfragile type that would be diagnosed as topologically trivial using symmetry\nindicators, and construct a number of microscopic models exhibiting this phase.\nOur work is expected to have important consequences given the central role\nfragile topological phases are expected to play in novel two-dimensional\nmaterials such as twisted bilayer graphene.",
        "positive": "YAG nano-light sources with high Ce concentration: We investigate the luminescence properties of 10 nm YAG nanoparticles doped\nwith Ce ions at 0.2%, 4% and 13% that are designed as active probes for\nScanning Near field Optical Microscopy. They are produced by a physical method\nwithout any subsequent treatment, which is imposed by the desired application.\nThe structural analysis reveals the amorphous nature of the particles, which we\nrelate to some compositional defect as indicated by the elemental analysis. The\noptimum emission is obtained with a doping level of 4%. The emission of the YAG\nnanoparticles doped at 0.2% is strongly perturbed by the crystalline disorder\nwhereas the 13% doped particles hardly exhibit any luminescence. In the latter\ncase, the presence of Ce4+ ions is confirmed, indicating that the Ce\nconcentration is too high to be incorporated efficiently in YAG nanoparticles\nin the trivalent state. By a unique procedure combining cathodoluminescence and\nRutherford backscattering spectrometry, we demonstrate that the enhancement of\nthe particles luminescence yield is not proportional to the doping\nconcentration, the emission enhancement being larger than the Ce concentration\nincrease. Time-resolved photoluminescence reveals the presence of quenching\ncentres likely related to the crystalline disorder as well as the presence of\ntwo distinct Ce ions populations. Eventually, nano-cathodoluminescence\nindicates that the emission and therefore the distribution of the doping Ce\nions and of the defects are homogeneous."
    },
    {
        "anchor": "Resonant exciton transfer in mixed-dimensional heterostructures for\n  overcoming dimensional restrictions in optical processes: Nanomaterials exhibit unique optical phenomena, in particular excitonic\nquantum processes occurring at room temperature. The low dimensionality,\nhowever, imposes strict requirements for conventional optical excitation, and\nan approach for bypassing such restrictions is desirable. Here we report on\nexciton transfer in carbon-nanotube/tungsten-diselenide heterostructures, where\nband alignment can be systematically varied. The mixed-dimensional\nheterostructures display a pronounced exciton reservoir effect where the\nlonger-lifetime excitons within the two-dimensional semiconductor are funneled\ninto carbon nanotubes through diffusion. This new excitation pathway presents\nseveral advantages, including larger absorption areas, broadband spectral\nresponse, and polarization-independent efficiency. When band alignment is\nresonant, we observe substantially more efficient excitation via tungsten\ndiselenide compared to direct excitation of the nanotube. We further\ndemonstrate simultaneous bright emission from an array of carbon nanotubes with\nvaried chiralities and orientations. Our findings show the potential of\nmixed-dimensional heterostructures and band alignment engineering for energy\nharvesting and quantum applications through exciton manipulation.",
        "positive": "Computational implementation of the Kubo formula for the static\n  conductance: application to two-dimensional quantum dots: Kubo formula is used to get the d.c conductance of a statistical ensemble of\ntwo-dimensional clusters of the square lattice in the presence of standard\ndiagonal disorder, a uniform magnetic field and random magnetic fluxes. Working\nwithin a one-band tight-binding approach the calculation is quite general. The\nshape of the cluster is rectangular with ideal leads attached to opposite\ncorners. Both geometrical characteristics and physical parameters can be easily\nselected. The output is just the conductance of a system of given parameters or\na statistical ensemble of conductances measured for different disorder\nrealizations."
    },
    {
        "anchor": "Theory of spin-coherent transport through a defect spin state in a\n  metal/ferromagnet tunnel junction during ferromagnetic resonance: We describe the coherent interaction between a defect spin at the interface\nof a ferromagnet and a non-magnetic material, under bias and when the\nmagnetization of the ferromagnetic contact precesses during ferromagnetic\nresonance. The magnet filters charge carriers by preferentially allowing in\nparallel spins, which leads to a dynamic spin accumulation on the defect. Local\neffective fields acting on the defect spin site modify the defect spin's\nprecession, which also modifies the charge current through the defect. This new\nform of current-detected spin resonance reveals the local environment of the\ndefect, and thus can yield the defect identity.",
        "positive": "Thermalization of nuclear spins in lanthanide molecular magnets: Single molecule magnets distinguish themselves in the field of quantum\nmagnetism through the ability to combine fundamental research with promising\napplications, the evolution of quantum spintronics in the last decade\nexemplifying the potential held by molecular based quantum devices. Notably,\nthe read-out and manipulation of the embedded nuclear spin states was used in\nproof of principle studies of quantum computation at the single molecule level.\nIn this paper we study the relaxation dynamics of the $^{159}$Tb nuclear spins\nin a diluted molecular crystal by using recently acquired understanding of the\nnonadiabatic dynamics of TbPc$_2$ molecules. We find that phonon modulated\nhyperfine interaction opens a direct relaxation channel between the nuclear\nspins and the phonon bath. We highlight the potential importance of the\ndiscovered mechanism for the theory of spin bath and the relaxation dynamics of\nthe molecular spins at crossover temperatures."
    },
    {
        "anchor": "Theory of Cross-correlated Electron-Magnon Transport Phenomena: Case of\n  Magnetic Topological Insulator: We study transport phenomena cross-correlated among the heat and electric\ncurrents of magnons and Dirac electrons on the surface of ferromagnetic\ntopological insulators. For a perpendicular magnetization, we calculate magnon-\n(electron-) drag anomalous Nernst/Seebeck (anomalous Ettingshausen/Peltier)\neffects and magnon-/electron-drag thermal Hall effects. The magnon-drag\nthermoelectric effects are interpreted to be caused by magnon-induced\nelectromotive force. When the magnetization has in-plane components, there\narise thermal/thermoelectric analogs of anisotropic magnetoresistance (AMR). In\nthe insulating state, the thermal AMR is realized as a magnonic analog of AMR.",
        "positive": "Cold Brownian motion in aqueous media via anti-Stokes photoluminescence: Advances in cryogenic sciences have enabled several observations of new\nlow-temperature physical phenomena including superconductivity, superfluidity,\nand Bose-Einstein condensates. Heat transfer is also critical in numerous\napplications including thermal management within integrated microelectronics\nand the regulation of plant-growth and development. Here we demonstrate that\nsingle-beam laser-trapping can be used to induce and quantify the local\nrefrigeration of aqueous media through analysis of the cold Brownian dynamics\nof individual Yb3+-doped yttrium lithium fluoride (YLF) crystals in an\ninhomogeneous temperature field via forward light scattering and\nback-focal-plane interferometry. A tunable, NIR continuous-wave laser is used\nto optically trap individual YLF crystals with an irradiance on the order of 1\nMW/cm2. Heat is transported out of the crystal lattice (across the solid /\nliquid interface) by anti-Stokes photoluminescence following upconversion of\nYb3+ excited states mediated by optical-phonon absorption. The cold Brownian\nmotion (CBM) analysis of individual YLF crystals indicates local cooling by >21\nC below ambient conditions suggesting a range of potential future applications."
    },
    {
        "anchor": "Anatomy of Demagnetizing and Exchange Fields in Magnetic Nanodots\n  Influenced by 3D Shape Modifications: Hysteresis loops of 3D ferromagnetic permalloy nano-half-balls (dots) with\n100 nm base diameter have been examined by means of LLG micromagnetic\nsimulations and finite element methods. Tests were carried out with two\northogonal directions of the externally applied field at 10 kA/(m.ns) field\nsweeping speed. The comparison of samples with different 3D modifications at\nthe sub-10nm scale, accessible by nowadays lithographic techniques, enables\nconclusions about different mechanisms of competition between demagnetizing and\nexchange fields. Design paradigms provided here can find possible applications\nin magneto-electronic devices.",
        "positive": "Platform for nodal topological superconductors in monolayer molybdenum\n  dichalcogenides: We propose a platform to realize nodal topological superconductors in a\nsuperconducting monolayer of MoX$_2$ (X$=$S, Se, Te) using an in-plane magnetic\nfield. The bulk nodal points appear where the spin splitting due to spin-orbit\ncoupling vanishes near the $\\pm \\boldsymbol{K}$ valleys of the Brillouin zone,\nand are six or twelve per valley in total. In the nodal topological\nsuperconducting phase, the nodal points are connected by flat bands of\nzero-energy Andreev edge states. These flat bands, which are protected by\nchiral symmetry, are present for all lattice-termination boundaries except\nzigzag."
    },
    {
        "anchor": "Large thermoelectric efficiency of doped polythiophene junction: a\n  density functional study: The thermoelectric properties of polythiophene (PT) coupled to the Au (111)\nelectrodes are studied based on density functional theory combined with\nnonequilibrium Green function formalism. Specially, the effect of Li and Cl\nadsorbents on the thermoelectric efficiency of the PT junction is investigated\nin different concentrations of the dopants for two lengths of the PT. Results\nshow that the presence of dopants can bring the structural changes in the\noligomer and modify the arrangement of the molecular levels leading to the\ndramatic changes in the transmission spectra of the junction. Therefore, the\nlarge enhancement in thermopower and consequently figure of merit is obtained\nby dopants which makes the doped PT junction as a beneficial thermoelectric\ndevice.",
        "positive": "Thermodynamics and Transport in Mesoscopic Disordered Networks: We describe the effects of phase coherence on transport and thermodynamic\nproperties of a disordered conducting network. In analogy with\nweak-localization correction, we calculate the phase coherence contribution to\nthe magnetic response of mesoscopic metallic isolated networks. It is related\nto the return probability for a diffusive particle on the corresponding\nnetwork. By solving the diffusion equation on various types of networks,\nincluding a ring with arms, an infinite square network or a chain of connected\nrings, we deduce the magnetic response. As it is the case for transport\nproperties --weak-localization corrections or universal conductance\nfluctuations-- the magnetic response can be written in term of a single\nfunction S called spectral function which is related to the spatial average of\nthe return probability on the network. We have found that the magnetization of\nan ensemble of CONNECTED rings is of the same order of magnitude as if the\nrings were disconnected."
    },
    {
        "anchor": "Reducing disorder in PbTe nanowires for Majorana research: Material challenges are the key issue in Majorana nanowires where surface\ndisorder constrains device performance. Here, we tackle this challenge by\nembedding PbTe nanowires within a latticematched crystal, an oxide-free\nenvironment. The wire edges are shaped by self-organized growth instead of\nlithography, resulting in nearly-atomic-flat facets along both cross-sectional\nand longitudinal directions. Quantized conductance plateaus are observed at\nzero magnetic field with channel lengths reaching 1.54 $\\mu$m, significantly\nsurpassing the state-of-the-art of III-V nanowires (nearly an\norder-of-magnitude improvement compared to InSb). Coupling PbTe to a Pb film\nunveils a flat interface spanning microns and a large superconducting gap of 1\nmeV. Our results meet the stringent low-disorder requirement for the definitive\nobservation of Majoranas.",
        "positive": "Magnetic Skyrmion Transport in a Nanotrack With Spatially Varying\n  Damping and Non-adiabatic Torque: Reliable transport of magnetic skyrmions is required for any future\nskyrmion-based information processing devices. Here we present a micromagnetic\nstudy of the in-plane current-driven motion of a skyrmion in a ferromagnetic\nnanotrack with spatially sinusoidally varying Gilbert damping and/or\nnon-adiabatic spin-transfer torque coefficients. It is found that the skyrmion\nmoves in a sinusoidal pattern as a result of the spatially varying Gilbert\ndamping and/or non-adiabatic spin-transfer torque in the nanotrack, which could\nprevent the destruction of the skyrmion caused by the skyrmion Hall effect. The\nresults provide a guide for designing and developing the skyrmion transport\nchannel in skyrmion-based spintronic applications."
    },
    {
        "anchor": "A Fokker-Planck Approach for Modeling the Stochastic Phenomena in\n  Magnetic and Resistive Random Access Memory Devices: Embedded non-volatile memory technologies such as resistive random access\nmemory (RRAM) and spin-transfer torque magnetic RAM (STT MRAM) are increasingly\nbeing researched for application in neuromorphic computing and hardware\naccelerators for AI. However, the stochastic write processes in these memory\ntechnologies affect their yield and need to be studied alongside process\nvariations, which drastically increase the complexity of yield analysis using\nthe Monte Carlo approach. Therefore, we propose an approach based on the\nFokker-Planck equation for modeling the stochastic write processes in STT MRAM\nand RRAM devices. Moreover, we show that our proposed approach can reproduce\nthe experimental results for both STT-MRAM and RRAM devices.",
        "positive": "Gate-tunable negative differential conductance in hybrid\n  semiconductor-superconductor devices: Negative differential conductance (NDC) manifests as a significant\ncharacteristic of various underlying physics and transport processes in hybrid\nsuperconducting devices. In this work, we report the observation of\ngate-tunable NDC outside the superconducting energy gap on two types of hybrid\nsemiconductor-superconductor devices, i.e., normal metal-superconducting\nnanowire-normal metal and normal metal-superconducting nanowire-superconductor\ndevices. Specifically, we study the dependence of the NDCs on back-gate voltage\nand magnetic field. When the back-gate voltage decreases, these NDCs weaken and\nevolve into positive differential conductance dips; and meanwhile they move\naway from the superconducting gap towards high bias voltage, and disappear\neventually. In addition, with the increase of magnetic field, the NDCs/dips\nfollow the evolution of the superconducting gap, and disappear when the gap\ncloses. We interpret these observations and reach a good agreement by combining\nthe Blonder-Tinkham-Klapwijk (BTK) model and the critical supercurrent effect\nin the nanowire, which we call the BTK-supercurrent model. Our results provide\nan in-depth understanding of the tunneling transport in hybrid\nsemiconductor-superconductor devices."
    },
    {
        "anchor": "Edge states, spin transport and impurity induced local density of states\n  in spin-orbit coupled graphene: We study graphene which has both spin-orbit coupling (SOC), taken to be of\nthe Kane-Mele form, and a Zeeman field induced due to proximity to a\nferromagnetic material. We show that a zigzag interface of graphene having SOC\nwith its pristine counterpart hosts robust chiral edge modes in spite of the\ngapless nature of the pristine graphene; such modes do not occur for armchair\ninterfaces. Next we study the change in the local density of states (LDOS) due\nto the presence of an impurity in graphene with SOC and Zeeman field, and\ndemonstrate that the Fourier transform of the LDOS close to the Dirac points\ncan act as a measure of the strength of the spin-orbit coupling; in addition,\nfor a specific distribution of impurity atoms, the LDOS is controlled by a\ndestructive interference effect of graphene electrons which is a direct\nconsequence of their Dirac nature. Finally, we study transport across junctions\nwhich separates spin-orbit coupled graphene with Kane-Mele and Rashba terms\nfrom pristine graphene both in the presence and absence of a Zeeman field. We\ndemonstrate that such junctions are generally spin active, namely, they can\nrotate the spin so that an incident electron which is spin polarized along some\ndirection has a finite probability of being transmitted with the opposite spin.\nThis leads to a finite, electrically controllable, spin current in such\ngraphene junctions. We discuss possible experiments which can probe our\ntheoretical predictions.",
        "positive": "Temperature Dependent Electronic Structure in a Higher Order Topological\n  Insulator Candidate EuIn$_2$As$_2$: The higher order topological insulator (HOTI) has enticed enormous research\ninterests owing to its novelty in supporting gapless states along the hinges of\nthe crystal. Despite several theoretical predictions, enough experimental\nconfirmation of HOTI state in crystalline solids is still lacking. It has been\nwell known that interplay between topology and magnetism can give rise to\nvarious magnetic topological states including HOTI and Axion insulator states.\nHere using the high-resolution angle-resolved photoemission spectroscopy\n(ARPES) combined with the first-principles calculations, we report a systematic\nstudy on the electronic band topology across the magnetic phase transition in\nEuIn2As2 which possesses an antiferromagnetic ground state below 16 K.\nAntiferromagnetic EuIn2As2 has been predicted to host both the Axion insulator\nand HOTI phase. Our experimental results show the clear signature of the\nevolution of the topological state across the magnetic transition. Our study\nthus especially suited to understand the interaction of higher order topology\nwith magnetism in materials."
    },
    {
        "anchor": "Spatial Fluctuations of Helical Dirac Fermions on the Surface of\n  Topological Insulators: Surfaces of topological insulators host a new class of states with Dirac\ndispersion and helical spin texture. Potential quantum computing and spintronic\napplications using these states require manipulation of their electronic\nproperties at the Dirac energy of their band structure by inducing magnetism or\nsuperconductivity through doping and proximity effect. Yet, the response of\nthese states near the Dirac energy in their band structure to various\nperturbations has remained unexplored. Here we use spectroscopic mapping with\nthe scanning tunneling microscope to study their response to magnetic and\nnon-magnetic bulk dopants in Bi2Te3 and Bi2Se3. Far from the Dirac energy\nhelicity provides remarkable resilience to backscattering even in the presence\nof ferromagnetism. However, approaching the Dirac point, where the surface\nstates' wavelength diverges bulk doping results in pronounced nanoscale spatial\nfluctuations of energy, momentum, and helicity. Our results and their\nconnection with similar studies of Dirac electrons in graphene demonstrate that\nwhile backscattering and localization are absent for Dirac topological surface\nstates, reducing charge defects is required for both tuning the chemical\npotential to Dirac energy and achieving high electrical mobility for these\nnovel states.",
        "positive": "Heat Capacity of Mesoscopic Superconducting Disks: We study the heat capacity of isolated giant vortex states, which are good\nangular momentum ($L$) states, in a mesoscopic superconducting disk using the\nGinzburg-Landau (GL) theory. At small magnetic fields the $L$=0 state\nqualitatively behaves like the bulk sample characterized by a discontinuity in\nheat capacity at $T_c$. As the field is increased the discontinuity slowly\nturns into a continuous change which is a finite size effect. The higher $L$\nstates show a continuous change in heat capacity at $T_c$ at all fields. We\nalso show that for these higher $L$ states, the behavior of the peak position\nwith change in field is related to the paramagnetic Meissner effect\n(irreversible) and can lead to an unambiguous observation of positive\nmagnetization in mesoscopic superconductors."
    },
    {
        "anchor": "Pseudospin valve in bilayer graphene: towards graphene-based\n  pseudospintronics: We propose a non-magnetic, pseudospin-based version of a spin valve, in which\nthe pseudospin polarization in neighboring regions of a graphene bilayer is\ncontrolled by external gates. Numerical calculations demonstrate a large on-off\nratio of such a device. This finding holds promise for the realization of\npseudospintronics: a form of electronics based upon the manipulation of\npseudospin analogous to the control of physical spin in spintronics\napplications.",
        "positive": "Quantum Time-evolution in Qubit Readout Process with a Josephson\n  Bifurcation Amplifier: We analyzed the Josephson bifurcation amplifier (JBA) readout process of a\nsuperconducting qubit quantum mechanically. This was achieved by employing\nnumerical analyses of the dynamics of the density operator of a driven\nnonlinear oscillator and a qubit coupled system during the measurement process.\nIn purely quantum cases, the wavefunction of the JBA is trapped in a\nquasienergy-state, and bifurcation is impossible. Introducing decoherence\nenables us to reproduce the bifurcation with a finite hysteresis. Moreover, we\ndiscuss in detail the dynamics involved when a qubit is initially in a\nsuperposition state. We have observed the qubit-probe (JBA) entangled state and\nit is divided into two separable states at the moment of the JBA transition\nbegins. This corresponds to \"projection\". To readout the measurement result,\nhowever, we must wait until the two JBA states are macroscopically well\nseparated. The waiting time is determined by the strength of the decoherence in\nthe JBA."
    },
    {
        "anchor": "Coherent coupling between a quantum dot and a donor in silicon: Individual donors in silicon chips are used as quantum bits with extremely\nlow error rates. However, physical realizations have been limited to one donor\nbecause their atomic size causes fabrication challenges. Quantum dot qubits, in\ncontrast, are highly adjustable using electrical gate voltages. This\nadjustability could be leveraged to deterministically couple donors to quantum\ndots in arrays of qubits. In this work, we demonstrate the coherent interaction\nof a $^{31}$P donor electron with the electron of a metal-oxide-semiconductor\nquantum dot. We form a logical qubit encoded in the spin singlet and triplet\nstates of the two-electron system. We show that the donor nuclear spin drives\ncoherent rotations between the electronic qubit states through the contact\nhyperfine interaction. This provides every key element for compact two-electron\nspin qubits requiring only a single dot and no additional magnetic field\ngradients, as well as a means to interact with the nuclear spin qubit.",
        "positive": "Infrared Dynamics of Cold Atoms on Hot Graphene Membranes: We study the infrared dynamics of low-energy atoms interacting with a sample\nof suspended graphene at finite temperature. The dynamics exhibits severe\ninfrared divergences order by order in perturbation theory as a result of the\nsingular nature of low-energy flexural phonon emission. Our model can be viewed\nas a two-channel generalization of the independent boson model with asymmetric\natom-phonon coupling. This allows us to take advantage of the exact\nnon-perturbative solution of the independent boson model in the stronger\nchannel while treating the weaker one perturbatively. In the low-energy limit,\nthe exact solution can be viewed as a resummation (exponentiation) of the most\ndivergent diagrams in the perturbative expansion. As a result of this\nprocedure, we obtain the atom's Green function which we use to calculate the\natom damping rate, a quantity equal to the quantum sticking rate. A\ncharacteristic feature of our results is that the Green's function retains a\nweak, infrared cutoff dependence that reflects the reduced dimensionality of\nthe problem. As a consequence, we predict a measurable dependence of the\nsticking rate on graphene sample size. We provide detailed predictions for the\nsticking rate of atomic hydrogen as a function of temperature and sample size.\nThe resummation yields an enhanced sticking rate relative to the conventional\nFermi golden rule result (equivalent to the one-loop atom self-energy), as\nhigher-order processes increase damping at finite temperature."
    },
    {
        "anchor": "Time-dependent density-functional theory for ultrafast interband\n  excitations: We formulate a time-dependent density functional theory (TDDFT) in terms of\nthe density matrix to study ultrafast phenomena in semiconductor structures. A\nsystem of equations for the density matrix components, which is equivalent to\nthe time-dependent Kohn-Sham equation, is derived. From this we obtain a TDDFT\nversion of the semiconductor Bloch equations, where the electronic many-body\neffects are taken into account in principle exactly. As an example, we study\nthe optical response of a three-dimensional two-band insulator to an external\nshort-time pulsed laser field. We show that the optical absorption spectrum\nacquires excitonic features when the exchange-correlation potential contains a\n$1/q^{2}$ Coulomb singularity. A qualitative comparison of the TDDFT optical\nabsorption spectra with the corresponding results obtained within the\nHartree-Fock approximation is made.",
        "positive": "A tunable plasmonic resonator using kinetic 2D inductance and patch\n  capacitance: We have studied microwave response of a high-mobility two-dimensional\nelectron system (2DES) contacted by two side electrodes. Using kinetic\ninductance of the 2DES and inter-electrode capacitance, we have constructed a\nsubwavelength 2D plasmonic resonator. We have shown that the resonant frequency\nof this circuit can be controlled by 2D electron density, external magnetic\nfield, or size of the electrodes. This opens up possibilities for using arrays\nof plasmonic circuits as tunable components in different frequency ranges."
    },
    {
        "anchor": "Metal-Insulator transition in 8-Pmmn Borophene under perpendicular\n  incidence of electromagnetic radiation: The energy spectrum for the problem of 8-Pmmn borophene's electronic carriers\nunder perpendicular incidence of electromagnetic waves is studied without the\nuse of any perturbative technique. This allows to study the effects of very\nstrong fields. To obtain the spectrum and wavefunctions, the time-dependent\nDirac equation is solved by using a frame moving with the space-time cone of\nthe wave, i.e., by transforming the equation into an ordinary differential\nequation in terms of the wave-phase, leading to an electron-wave quasiparticle.\nThe limiting case of strong fields is thus analyzed.The resulting\neigenfunctions obey a generalized Mathieu equation,i.e., of a classical\nparametric pendulum. The energy spectrum presents bands, and a gap at the Fermi\nenergy. The gaps are due to the space-time diffraction of electrons in phase\nwith the electromagnetic field, i.e., electrons in borophene acquire an\neffective mass under strong electromagnetic radiation",
        "positive": "On two-dimensional exciton bound by distant ionized-donor in a narrow\n  quantum well: The ground state energy of exciton bound by distant ionized donor impurity in\ntwo-dimensional semiconductor quantum well (QW) is studied theoretically within\nthe Hartree approach in the effective mass approximation. The influence of the\ndistance between QW plane and ionized donor, as well as of the electron-hole\nmass ratio, the magnetic field aligned across the QW plane and dielectric\nconstant of the barrier material on the stability of exciton bound by ionized\ndonor impurity is analyzed and discussed."
    },
    {
        "anchor": "Sign reversal of field like spin-orbit torque in ultrathin\n  Chromium/Nickel bilayer: In this work report unconventional sign change of field like spin orbit\ntorque in ultra-thin Chromium(1.5nm-5nm)/Nickel(8nm) bi-layer. We performed\nstandard spin-torque ferromagnetic resonance (ST-FMR) experiment in Cr/Ni\nbi-layer by passing radio frequency current and measuring DC voltage. We\nobserve that when thickness of Cr layer is critically low (<6nm) spin orbit\ntorque by Cr on Ni significantly increases. Most importantly the sign of field\nlike torque is opposite to the Oersted field generated torque. To verify\ninterracial nature of this torque, 2 nm thin Cu is inserted between Cr and Ni\nand field like torque behaves same as Oersted field induced torque. Hence\npossible origin of such unconventional sign change of field like torque could\nbe inter-facial Rashba like spin orbit interaction which is present between Cr\nand Ni but vanishes in Cr/Cu/Ni hetero-structure. From our experiment we can\nestimate that approximately 35 Oe of effective Rashba like magnetic field is\ncreated on 8 nm thicker Ni layer, when 1E12 A/m^2 current flows through Cr\nlayer. All experiments are done at room temperature. So Cr thin film is\nexpected to behave like paramagnet (Neel temperature of bulk Cr is 311K). Hence\nCr can be a good choice as a heavy metal to employ large spin orbit torque\ncombining bulk spin Hall effect and inter-facial Rashba interaction.",
        "positive": "Interacting topological frequency converter: We show that an interacting two-spin model subjected to two circularly\npolarized drives enables a feasible realization of a correlated topological\nphase in synthetic dimensions. The topological observable is given by a\nquantized frequency conversion between the dynamical drives, which is why we\ncoin it the interacting topological frequency converter (ITFC). The ITFC is\ncharacterized by the interplay of interaction and synthetic dimension. This\ngives rise to striking topological phenomena that have no counterpart in the\nnoninteracting regime. By calculating the topological phase diagrams as a\nfunction of interaction strength, we predict an enhancement of frequency\nconversion as a direct manifestation of the correlated topological response of\nthe ITFC."
    },
    {
        "anchor": "Topological Magnon Bands in Ferromagnetic Star Lattice: The experimental observation of topological magnon bands and thermal Hall\neffect in a kagom\\'e lattice ferromagnet Cu(1-3, bdc) has inspired the search\nfor topological magnon effects in various insulating ferromagnets that lack an\ninversion center allowing a Dzyaloshinskii-Moriya (DM) spin-orbit interaction.\nThe star lattice (also known as the decorated honeycomb lattice) ferromagnets\nis an ideal candidate for this purpose because it is a variant of the kagom\\'e\nlattice with additional links that connect the up-pointing and down-pointing\ntriangles. This gives rise to twice the unit cell of the kagom\\'e lattice,\nhence a more interesting topological magnon effects. In particular, the\ntriangular bridges on the star lattice can be coupled either ferromagnetically\nor antiferromagnetically which is not possible on the kagome lattice\nferromagnets. Here, we study DM-induced topological magnon bands, chiral edge\nmodes, and thermal magnon Hall effect on the star lattice ferromagnet in\ndifferent parameter regimes. The star lattice can also be visualized as the\nparent material from which topological magnon bands can be realized for the\nkagom\\'e and honeycomb lattices in some limiting cases.",
        "positive": "\"Phase Diagram\" of the Spin Hall Effect: We obtain analytic formulas for the frequency-dependent spin-Hall\nconductivity of a two-dimensional electron gas (2DEG) in the presence of\nimpurities, linear spin-orbit Rashba interaction, and external magnetic field\nperpendicular to the 2DEG. We show how different mechanisms (skew-scattering,\nside-jump, and spin precession) can be brought in or out of focus by changing\ncontrollable parameters such as frequency, magnetic field, and temperature. We\nfind, in particular, that the d.c. spin Hall conductivity vanishes in the\nabsence of a magnetic field, while a magnetic field restores the\nskew-scattering and side-jump contributions proportionally to the ratio of\nmagnetic and Rashba fields."
    },
    {
        "anchor": "Spin and charge optical conductivities in spin-orbit coupled systems: We study the frequency dependent spin- and charge- conductivity tensors of a\ntwo-dimensional electron gas (2DEG) with Rashba and Dresselhaus spin-orbit\ninteraction. We show that the angular anisotropy of the spin-splitting energy\ninduced by the interplay between the Rashba and Dresselhaus couplings gives\nrise to a characteristic spectral behavior of the spin and charge response\nwhich is significantly different from that of pure Rashba or Dresselhaus case.\nSuch new spectral structures open the possibility for control of the optical\nresponse by applying an external bias and/or by adjusting the light frequency.\nIn addition, it is shown that the relative strength of the spin-orbit coupling\nparameters can be obtained through optical probing.",
        "positive": "Dephasing of spin and charge interference in helical Luttinger liquids: We consider a four-terminal Aharonov-Bohm interference setup formed out of\ntwo edges of a quantum spin Hall insulator, supporting helical Luttinger\nliquids (HLLs). We show that the temperature and bias dependence of the\ninterference oscillations are linked to the amount of spin flips in tunneling\nbetween two HLLs which is a unique signature of a HLL. We predict that spin\ndephasing depends on the electron-electron (e-e) interaction but differently\nfrom the charge dephasing due to distinct dominant tunneling excitations. In\ncontrast, in a spinful Luttinger liquid with SU(2) invariance, uncharged spin\nexcitations can carry spin current without dephasing in spite of the presence\nof e-e interactions."
    },
    {
        "anchor": "Spin and orbital Hall currents detected via current induced\n  magneto-optical Kerr effect in V and Pt: We have studied the film thickness dependence of the current-induced\nmagneto-optical Kerr effect in Pt and V thin films. The Kerr signal for Pt\nshows little dependence on the thickness in the range studied (20-80 nm). In\ncontrast, the signal for V increases with increasing thickness and saturates at\na thickness near 100 nm to a value significantly larger than that of Pt. These\nexperimental results are accounted for assuming that spin and orbital Hall\neffects are responsible for the Kerr signal. We show that the Kerr signal is\nproportional to the product of the dc spin (orbital) Hall conductivity and the\nenergy derivative of the ac spin (orbital) Hall conductivity. Contributions\nfrom the spin and orbital Hall effects mostly add up for V whereas they cancel\nout for Pt. Assuming that the orbital Hall conductivity matches that predicted\nfrom first-principles calculations, the thickness dependence of the Kerr signal\nsuggests that the orbital diffusion length of V is considerably smaller\ncompared to its spin diffusion length.",
        "positive": "Nonequilibrium transport through a quantum dot weakly coupled to\n  Luttinger liquids: We study the nonequlibrium transport through a quantum dot weakly coupled to\nLuttinger liquids (LL). A general current expression is derived by using\nnonequilibrium Green function method. Then a special case of the dot with only\na single energy level is discussed. As a function of the dot's energy level, we\nfind that the current as well as differential conductance is strongly\nrenormalized by the interaction in the LL leads. In comparison with the system\nwith Fermi liquid (FL) leads, the current is suppressed, consistent with the\nsuppression of the electron tunneling density of states of the LL; and the\noutset of the resonant tunneling is shifted to higher bias voltages. Besides,\nthe linear conductance obtained by Furusaki using master equation can be\nreproduced from our result."
    },
    {
        "anchor": "Quantum transport in honeycomb lattice ribbons with zigzag edges: A\n  theoretical study: We explore electron transport properties in honeycomb lattice ribbons with\nzigzag edges coupled to two semi-infinite one-dimensional metallic electrodes.\nThe calculations are based on the tight-binding model and the Green's function\nmethod, which numerically compute the conductance-energy and current-voltage\ncharacteristics as functions of the lengths and widths of the ribbons. Our\nnumerical results predict that for such a ribbon an energy gap always appears\nin the conductance spectrum across the energy E=0. With the increase of the\nsize of the ribbon, the gap gradually decreases but it never vanishes. This\nclearly manifests that a honeycomb lattice ribbon with zigzag edges always\nexhibits the semiconducting behavior, and it becomes much more clearly visible\nfrom our presented current-voltage characteristics.",
        "positive": "Photoassisted shot noise spectroscopy at fractional filling factor: We study the photoassisted shot noise generated by a periodic voltage in the\nfractional quantum Hall regime. Fluctuations of the current are due to the\npresence of a quantum point contact operating in the weak backscattering\nregime. We show how to reconstruct the photoassisted absorption and emission\nprobabilities by varying independently the dc and ac contributions to the\nvoltage drive. This is made possible by the peculiar power-law behavior of the\ntunneling rates in the chiral Luttinger liquid theory, which allow to\napproximate the typical infinite sums of the photoassisted transport formalism\nin a simple and particularly convenient way."
    },
    {
        "anchor": "Tight-binding Piezoelectric Theory and Electromechanical Coupling\n  Correlations for Transition Metal Dichalcogenide Monolayers: The lack of inversion symmetry in semiconducting transition metal\ndichalcogenide monolayers (TMDMs) enables a considerable molecular-level\nintrinsic piezoelectricity, which opens prospects for atomically-thin\npiezotronics and optoelectronics. Here, based on the tight-binding (TB)\napproach and Berry phase polarization theory, we establish an atomic-scale TB\ntheory for demonstrating piezoelectric physics in TMDMs. Using the TB\npiezoelectric theory, we predict their electronic Gr\\\"{u}neisen parameters\n(EGP) which measure the electron-phonon couplings. By virtue of the constructed\nanalytical piezoelectric model, we further reveal the correlation between the\nelectronic contribution to piezoelectric coefficients and strain-induced\npseudomagnetic gauge field (PMF). These predicted EGP and PMF for TMDMs are\nexperimentally testable, and hence the TB piezoelectric model is an alternative\ntheoretical framework for calculating electron-phonon interactions and PMF.",
        "positive": "Delocalised oxygen as the origin of two-level defects in Josephson\n  junctions: One of the key problems facing superconducting qubits and other Josephson\njunction devices is the decohering effects of bi-stable material defects.\nAlthough a variety of phenomenological models exist, the true microscopic\norigin of these defects remains elusive. For the first time we show that these\ndefects may arise from delocalisation of the atomic position of the oxygen in\nthe oxide forming the Josephson junction barrier. Using a microscopic model, we\ncompute experimentally observable parameters for phase qubits. Such defects are\ncharge neutral but have non-zero response to both applied electric field and\nstrain. This may explain the observed long coherence time of two-level defects\nin the presence of charge noise, while still coupling to the junction electric\nfield and substrate phonons."
    },
    {
        "anchor": "Logic-Memory Device of a Mechanical Resonator: We report multifunctional operation based on the nonlinear dynamics in a\nsingle microelectromechanical system (MEMS) resonator. This Letter focuses on a\nlogic-memory device that uses a closed loop control and a nonlinear MEMS\nresonator in which multiple states coexist. To obtain both logic and memory\noperations in a MEMS resonator, we examine the nonlinear dynamics with and\nwithout control input. Based on both experiments and numerical simulations, we\ndevelop a novel device that combines an OR gate and memory functions in a\nsingle MEMS resonator.",
        "positive": "Origin of adiabatic and non-adiabatic spin transfer torques in\n  current-driven magnetic domain wall motion: A consistent theory to describe the correlated dynamics of quantum mechanical\nitinerant spins and semiclassical local magnetization is given. We consider the\nitinerant spins as quantum mechanical operators, whereas local moments are\nconsidered within classical Lagrangian formalism. By appropriately treating\nfluctuation space spanned by basis functions, including a zero-mode wave\nfunction, we construct coupled equations of motion for the collective\ncoordinate of the center-of-mass motion and the localized zero-mode coordinate\nperpendicular to the domain wall plane. By solving them, we demonstrate that\nthe correlated dynamics is understood through a hierarchy of two time scales:\nBoltzmann relaxation time when a non-adiabatic part of the spin-transfer torque\nappears, and Gilbert damping time when adiabatic part comes up."
    },
    {
        "anchor": "Single photon Mach-Zehnder interferometer for quantum networks based on\n  the Single Photon Faraday Effect: principle and applications: Combining the recent progress in semiconductor nanostructures along with the\nversatility of photonic crystals in confining and manipulating light, quantum\nnetworks allow for the prospect of an integrated and low power quantum\ntechnology. Within quantum networks, which consist of a system of waveguides\nand nanocavities with embedded quantum dots, it has been demonstrated in theory\nthat many-qubit states stored in electron spins could be teleported from one\nquantum dot to another via a single photon using the Single Photon Faraday\nEffect. However, in addition to being able to transfer quantum information from\none location to another, quantum networks need added functionality such as (1)\ncontrolling the flow of the quantum information and (2) performing specific\noperations on qubits that can be easily integrated. In this paper, we show how\nin principle a single photon Mach-Zehnder interferometer, which uses the\nconcept of the single photon Faraday Effect to manipulate the geometrical phase\nof a single photon, can be operated both as a switch to control the flow of\nquantum information inside the quantum network and as various single qubit\nquantum gates to perform operations on a single photon. Our proposed\nMach-Zehnder interferometer can be fully integrated as part of a quantum\nnetwork on a chip. Given that the X gate, the Z gate, and the XZ gate are\nessential for the implementation of quantum teleportation, we show explicitly\ntheir implementation by means of our proposed single photon Mach-Zehnder\ninterferometer. We also show explicitly the implementation of the Hadamard gate\nand the single-qubit phase gate, which are needed to complete the universal set\nof quantum gates for integrated quantum computing in a quantum network.",
        "positive": "Rashba-splitting of the Dirac points and the symmetry breaking in the\n  strained artificial graphene: The effect of Rashba spin-orbit interaction and anisotropic strain on the\nelectronic, optical and thermodynamic properties of artificial graphene-like\nsuperlattice composed of InAs-GaAs quantum dots has been considered\ntheoretically. The electronic energy dispersions have been obtained using\nGreen's function formalism in combination with Fourier transformation to the\nreciprocal space and an exact diagonalization technique. We have observed a\nsplitting of Dirac points and appearance of edditional Dirac-like points due to\nthe Rashba spin-orbit interaction. Breaking of the hexagonal symmetry of the\ndispersion surfaces caused by the strain anisotropy is observed as well. It is\nshown that both the spin-orbit interaction and strain anisotropy have a\nqualitative impact on the measurable characteristics of the considered\nstructure and can be used as effective tools to control the performance of\ndevices based on artificial graphene."
    },
    {
        "anchor": "Power laws in surface state LDOS oscillations near a step edge: In this paper we indicate a general method to calculate the power law that\ngoverns how electronic LDOS oscillations decay far away from a surface step\nedge (or any local linear barrier), in the energy range when only 2D surface\nstates are relevant. We identify the critical aspects of the 2D surface state\nband structure that contribute to these decaying oscillations and illustrate\nour derived formula with actual examples.",
        "positive": "Comment on \"Weak localization in GaMnAs: evidence of impurity band\n  transport\" by L. P. Rokhinson et. al. (Phys. Rev. B, 76, 161201 R;\n  arXivCond-mat:0707.2416): We suggest that negative magnetoresistance in small magnetic fields at\ntemperatures lower than 3 K reported in the paper under discussion may be\nrelated to superconducting transition in In leads (with Tc = 3.4 K)."
    },
    {
        "anchor": "Phosphorene quantum dot electronic properties and gas sensing: Density functional theory calculations are performed on phosphorene quantum\ndots having different shapes and edge terminations to investigate their\nstructure stability, electronic properties, and gas sensing ability. All the\nselected phosphorene dots, namely hexagonal and triangular flakes with armchair\nand zigzag terminations, have positive binding energies which insure their\nstability even though the bond lengths are much longer than those in the\ninfinite phosphorene layer. It is found that all the selected hydrogen\npassivated quantum dots have a wide energy gap. In contrast, the partial\npassivation with sulfur decreases the gap. Moreover, it transforms the system\nfrom antiferromagnetic to ferromagnetic state. The energy gap of hexagonal\nzigzag cluster can be additionally tuned by electric field: narrowed by about\n1.7 eV for hydrogenated or broadened by 0.25 eV for partially sulfurated edges.\nIt is shown that phosphorene quantum dots successfully adsorb H2S, CH4, CO, NH3\ngas molecules either on their edge or surface. The highest adsorption energy is\nobtained for NH3 molecule, when it is placed over the surface. This adsorption\nis alleviated by in-plane electric field and hindered by perpendicular field.",
        "positive": "Enhanced spin Hall effect in strong magnetic disorder: We consider a two-dimensional electron gas in an inversion asymmetric layer\nand in the presence of spatially distributed magnetic impurities. We\ninvestigate the relationship between the geometrical properties of the\nwave-function and the system's spin dependent transport properties. A\nlocalization transition, arising when disorder is increased, is exhibited by\nthe appearance of a fractal state with finite inverse participation ratio.\nBelow the transition, interference effects modify the carrier's diffusion, as\nrevealed by the dependence on the scattering time of the power law exponents\ncharacterizing the spreading of a wave packet. Above the transition, in the\nstrong disorder regime, we find that the states are spin polarized and\nlocalized around the impurities. A significant enhancement of the spin current\ndevelops in this regime."
    },
    {
        "anchor": "Nonequilibrium transport and population inversion in double quantum dot\n  systems: We present a microscopic theory for both equilibrium and nonequilibrium\ntransport properties of coupled double quantum dots (DQD). A general formula\nfor current tunneling through the DQD is derived by the nonequilibrium Green's\nfunction method. Using a Hartree-Fock approach, effects of multi-level coupling\nand nonequilibrium electron distributions in resonant tunneling are considered.\nWe find that the peak in the resonant tunneling current through two symmetric\ndots will split only when the inter-dot coupling is stronger than dot-lead\ncoupling. We predict that population inversion can be achieved in one dot in\nthe nonequilibrium regime.",
        "positive": "Theory of moir\u00e9 localized excitons in transition-metal dichalcogenide\n  heterobilayers: Transition-metal dichalcogenide heterostructures exhibit moir\\'e patterns\nthat spatially modulate the electronic structure across the material's plane.\nFor certain material pairs, this modulation acts as a potential landscape with\ndeep, trigonally symmetric wells capable of localizing interlayer excitons,\nforming periodic arrays of quantum emitters. Here, we study these moir\\'e\nlocalized exciton states and their optical properties. By numerically solving\nthe two-body problem for an interacting electron-hole pair confined by a\ntrigonal potential, we compute the localized exciton spectra for different\npairs of materials. We derive optical selection rules for the different\nfamilies of localized states, each belonging to one of the irreducible\nrepresentations of the potential's symmetry group $C_{3v}$, and numerically\nestimate their polarization-resolved absorption spectra. We find that the\noptical response of localized moir\\'e interlayer excitons is dominated by\nstates belonging to the doubly-degenerate $E$ irreducible representation. Our\nresults provide new insights into the optical properties of artificially\nconfined excitons in two-dimensional semiconductors."
    },
    {
        "anchor": "Large even-odd spacing and $g$-factor anisotropy in PbTe quantum dots: PbTe is a semiconductor with promising properties for topological quantum\ncomputing applications. Here we characterize quantum dots in PbTe nanowires\nselectively grown on InP. Charge stability diagrams at zero magnetic field\nreveal large even-odd spacing between Coulomb blockade peaks, charging energies\nbelow 140$~\\mathrm{\\mu eV}$ and Kondo peaks in odd Coulomb diamonds. We\nattribute the large even-odd spacing to the large dielectric constant and small\neffective electron mass of PbTe. By studying the Zeeman-induced level and Kondo\nsplitting in finite magnetic fields, we extract the electron $g$-factor as a\nfunction of magnetic field direction. We find the $g$-factor tensor to be\nhighly anisotropic, with principal $g$-factors ranging from 0.9 to 22.4, and to\ndepend on the electronic configuration of the devices. These results indicate\nstrong Rashba spin-orbit interaction in our PbTe quantum dots.",
        "positive": "Some words on the \"phase transitions\" in magnetic mesoscopic system: \"Phase transitions\" between quantum and classical behaviour in large spin\nmagnetic systems discused."
    },
    {
        "anchor": "Orbital magnetism of graphene flakes: Orbital magnetism is studied for graphene flakes with various shapes and edge\nconfigurations using the tight-binding approximation. In the low-temperature\nregime where the thermal energy is much smaller than to the energy level\nspacing, the susceptibility rapidly changes between diamagnetism and\nparamagnetism as a function of Fermi energy, in accordance with the energy\nlevel structure. The susceptibility at charge neutral point is generally larger\nin armchair flake than in zigzag flake, and larger in hexagonal flake than in\ntriangular flake. As the temperature increases, the discrete structures due to\nthe quantum confinement are all gone, and the susceptibility approximates the\nbulk limit independently of the atomic configuration. The diamagnetic current\ncirculates entirely on the graphene flake at zero temperature, while in\nincreasing temperature it is localized near the edge with the characteristic\ndepth proportional to 1/T. We predict that the diamagnetism of graphene can be\nobserved using the alignment of graphene flakes in a feasible range of magnetic\nfield.",
        "positive": "Chirality-mediated bistability and strong frequency downshifting of the\n  gyrotropic resonance of a dynamically de-stiffened magnetic vortex: We demonstrate an enhanced, bidirectional, in-plane magnetic field tuning of\nthe gyrotropic resonance frequency of a magnetic vortex within a disk by\nintroducing a flat edge. When the core is in its vicinity, the flat edge\nlocally reduces the core's directional dynamic stiffness for movement parallel\nto the edge. This strongly reduces the net dynamic core stiffness, leading to\nthe gyrotropic frequency being significantly less than when the core is\ncentered (or located near the round edge). This leads to the measurable range\nof gyrotropic frequencies being more than doubled and also results in a clear\nchirality-mediated bistability of the gyrotropic resonance frequency due to\nwhat is effectively a chirality-dependence of the core's confining potential."
    },
    {
        "anchor": "Evidence of Landau levels and interactions in low-lying excitations of\n  composite fermions at 1/3 <= \u03bd<= 2/5: Excitation modes in the range $2/5 \\geq \\nu \\geq 1/3$ of the fractional\nquantum Hall regime are observed by resonant inelastic light scattering.\nSpectra of spin reversed excitations suggest a structure of lowest spin-split\nLandau levels of composite fermions that is similar to that of electrons.\nSpin-flip energies determined from spectra reveal significant composite fermion\ninteractions. The filling factor dependence of mode energies display an abrupt\nchange in the middle of the range when there is partial population of a\ncomposite fermion level.",
        "positive": "Bound electron states in the monolayer graphene with short-range\n  impurities: Bound electron states in impure graphene are considered. Short-range\nperturbations for defect and impurities of the types \"local chemical potential\"\nand \"local gap\" are taken into account."
    },
    {
        "anchor": "Coefficient of performance at maximum cooling power of a simplified\n  quantum dot refrigerator model with resistance: A simplified analytical model of single-level quantum dot (QD) refrigerator\nwas studied without considering the electron spin and Coulomb interaction.\nBased on the ballistic transport of electrons between two reservoirs across the\nQD, the Joule heat of the system was assumed to be generated from the Ohmic\ncontacts between the QD and reservoirs. By using the transition rate equation,\nthe performance of the QD refrigerator was studied with respect to the electron\ntransmission probability and the partition ratio (i.e., the fraction of Joule\nheat generated in the system that releases into the cold reservoir). The\nanalytical expression of the maximum coefficient of performance was obtained\nunder the exoreversible working condition. The Carnot-bound-dependent\ncoefficient of performance at maximum cooling power of the QD system was also\ndemonstrated numerically. The results of this work may provide some guidance\nfor the design of mesoscopic refrigerators.",
        "positive": "Mechanism for graphene-based optoelectronic switches by tuning surface\n  plasmon-polaritons in monolayer graphene: It is shown that one can explore the optical conductivity of graphene,\ntogether with the ability of controlling its electronic density by an applied\ngate voltage, in order to achieve resonant coupling between an external\nelectromagnetic radiation and surface plasmon-polaritons in the graphene layer.\nThis opens the possibility of electrical control of the intensity of light\nreflected inside a prism placed on top of the graphene layer, by switching\nbetween the regimes of total reflection and total absorption. The predicted\neffect can be used to build graphene-based opto-electronic switches."
    },
    {
        "anchor": "Induced superconducting correlations in the quantum anomalous Hall\n  insulator: Inducing Cooper pairing in a thin ferromagnetic topological insulator in the\nquantum anomalous Hall state (called quantum anomalous Hall insulator, QAHI) is\na promising way to realize topological superconductivity with associated chiral\nMajorana edge states. However, finding evidence of superconducting proximity\neffect in a QAHI has proven to be a considerable challenge due to inherent\nexperimental difficulties. Here we report the observation of crossed Andreev\nreflection (CAR) across a narrow superconducting Nb electrode contacting the\nchiral edge state of a QAHI, evinced by a negative nonlocal voltage measured\ndownstream from the grounded Nb electrode. This is an unambiguous signature of\ninduced superconducting pair correlation in the chiral edge state. Our\ntheoretical analysis demonstrates that CAR processes of the chiral edge are not\nstrongly dependent on the nature of the superconductivity that mediates them.\nNevertheless, the characteristic length of the CAR process is found to be much\nlonger than the superconducting correlation length in Nb, which suggests that\nthe CAR is in fact mediated by superconductivity induced on the QAHI surface.\nThe approach and results presented here provide a foundation for future studies\nof topological superconductivity and Majorana physics, as well as for the\nsearch for non-Abelian zero modes.",
        "positive": "Terahertz tuning of Dirac plasmons in Bi$_2$Se$_3$ Topological Insulator: Light can be strongly confined in sub-wavelength spatial regions through the\ninteraction with plasmons, the collective electronic modes appearing in metals\nand semiconductors. This confinement, which is particularly important in the\nterahertz spectral region, amplifies light-matter interaction and provides a\npowerful mechanism for efficiently generating non-linear optical phenomena.\nThese effects are particularly relevant in Dirac materials like graphene and\nTopological Insulators, where massless fermions show a naturally non-linear\noptical behavior in the terahertz range. The strong interaction scenario has\nbeen considered so far from the point of view of light. In this paper, we\ninvestigate instead the effect of strong interaction on the plasmon itself. In\nparticular, we will show that Dirac plasmons in Bi$_2$Se$_3$ Topological\nInsulator are strongly renormalized when excited by high-intensity terahertz\nradiation by displaying a huge red-shift down to 60% of its characteristic\nfrequency. This opens the road towards tunable terahertz non-linear optical\ndevices based on Topological Insulators."
    },
    {
        "anchor": "Anisotropic resistance with a 90-degree twist in a ferromagnetic Weyl\n  semimetal, Co2MnGa: Co$_2$MnGa is a ferromagnetic semimetal with Weyl nodal lines identified by\nARPES. We studied electrical transport in thin Co$_2$MnGa lamellae (10 $\\times$\n10 $\\times$ 0.4-5 microns) cut from single-crystals using a focused ion beam.\nThese crystals exhibit an unexpected and highly unusual planar resistance\nanisotropy ($\\sim$10 times) with principal axes that rotate by 90 degrees\nbetween the upper and lower faces. Using symmetry arguments and simulations, we\nfind that the observed resistance anisotropy resembles that of an isotropic\nconductor with anisotropic surface states that are impeded from hybridization\nwith bulk states. The origin of these states awaits further experiments that\ncan correlate the surface bands with the observed 90$^\\circ$-twist geometry.",
        "positive": "Magnetotransport along a boundary: From coherent electron focusing to\n  edge channel transport: We study theoretically how electrons, coherently injected at one point on the\nboundary of a two-dimensional electron system, are focused by a perpendicular\nmagnetic field $B$ onto another point on the boundary. Using the\nnon-equilibrium Green's function approach, we calculate the generalized 4-point\nHall resistance $R_{xy}$ as a function of B. In weak fields, $R_{xy}$ shows the\ncharacteristic equidistant peaks observed in the experiment and explained by\nclassical cyclotron motion along the boundary. In strong fields, $R_{xy}$ shows\na single extended plateau reflecting the quantum Hall effect. In intermediate\nfields, we find superimposed upon the lower Hall plateaus anomalous\noscillations, which are neither periodic in 1/B (quantum Hall effect) nor in\n$B$ (classical cyclotron motion). The oscillations are explained by the\ninterference between the occupied edge channels, which causes beatings in\n$R_{xy}$. In the case of two occupied edge channels, these beatings constitute\na new commensurability between the magnetic flux enclosed within the edge\nchannels and the flux quantum. Introducing decoherence and a partially specular\nboundary shows that this new effect is quite robust."
    },
    {
        "anchor": "Quantized conductance in a one-dimensional ballistic oxide nanodevice: Electric-field effect control of two-dimensional electron gases (2-DEG) has\nenabled the exploration of nanoscale electron quantum transport in\nsemiconductors. Beyond these classical materials, transition metal-oxide-based\nstructures have d-electronic states favoring the emergence of novel quantum\norders absent in conventional semiconductors. In this context, the\nLaAlO3/SrTiO3 interface that combines gate-tunable superconductivity and\nsizeable spin-orbit coupling is emerging as a promising platform to realize\ntopological superconductivity. However, the fabrication of nanodevices in which\nthe electronic properties of this oxide interface can be controlled at the\nnanoscale by field-effect remains a scientific and technological challenge.\nHere, we demonstrate the quantization of conductance in a ballistic quantum\npoint contact (QPC), formed by electrostatic confinement of the LaAlO3/SrTiO3\n2-DEG with a split-gate. Through finite source-drain voltage, we perform a\ncomprehensive spectroscopic investigation of the 3d energy levels inside the\nQPC, which can be regarded as a spectrometer able to probe Majorana states in\nan oxide 2-DEG.",
        "positive": "Second-order topological phases protected by chiral symmetry: We study second-order topological insulators and semimetals characterized by\nchiral symmetry. We investigate topological phase transitions of a model for\nconstruction of the two-dimensional second-order topological insulators\nprotected only by chiral symmetry. By the theory of the phase transitions, we\npropose a second-order topological semimetal and insulators with flat hinge\nbands in chiral-symmetric three-dimensional systems. The three-dimensional\nsecond-order topological phases can be obtained from the stacked\ntwo-dimensional second-order topological insulators with chiral symmetry.\nMoreover, we show that broken chiral symmetry in the three-dimensional\nsecond-order topological phase allows a second-order topological insulator with\nchiral hinge states. We also demonstrate the second-order topological phases by\nusing a lattice model."
    },
    {
        "anchor": "Long distance transport of magnon spin information in a magnetic\n  insulator at room temperature: The transport of spin information has been studied in various materials, such\nas metals, semiconductors and graphene. In these materials, spin is transported\nby diffusion of conduction electrons. Here we study the diffusion and\nrelaxation of spin in a magnetic insulator, where the large bandgap prohibits\nthe motion of electrons. Spin can still be transported, however, through the\ndiffusion of non-equilibrium magnons, the quanta of spin wave excitations in\nmagnetically ordered materials. Here we show experimentally that these magnons\ncan be excited and detected fully electrically in linear response, and can\ntransport spin angular momentum through the magnetic insulator yttrium iron\ngarnet (YIG) over distances as large as 40 micrometer. We identify two\ntransport regimes: the diffusion limited regime for distances shorter than the\nmagnon relaxation length, and the relaxation limited regime for larger\ndistances. With a model similar to the diffusion-relaxation model for electron\nspin transport in (semi)conducting materials, we extract the magnon relaxation\nlength lambda = 9.4 micrometer in a 200 nm thin YIG film at room temperature.",
        "positive": "Polariton-polariton scattering in microcavities: A microscopic theory: We apply the fermion commutation technique for composite bosons to\npolariton-polariton scattering in semiconductor planar microcavities.\nDerivations are presented in a simple and physically transparent fashion. A\nprocedure of orthogonolization of the initial and final two-exciton state\nwavefunctions is used to calculate the effective scattering matrix elements and\nthe scattering rates. We show how the bosonic stimulation of the scattering\nappears in this full fermionic approach whose equivalence to the bosonization\nmethod is thus demonstrated in the regime of low exciton density. We find an\nadditional contribution to polariton-polariton scattering due to the exciton\noscillator strength saturation, which we analyze as well. We present a theory\nof the polariton-polariton scattering with opposite spin orientations and show\nthat this scattering process takes place mainly via dark excitonic states.\nAnalytical estimations of the effective scattering amplitudes are given."
    },
    {
        "anchor": "Tunneling valley Hall effect driven by tilted Dirac fermions: Valleytronics is a research field utilizing a valley degree of freedom of\nelectrons for information processing and storage. A strong valley polarization\nis critical for realistic valleytronic applications. Here, we predict a\ntunneling valley Hall effect (TVHE) driven by tilted Dirac fermions in\nall-in-one tunnel junctions based on a two-dimensional (2D) valley material.\nDifferent doping of the electrode and spacer regions in these tunnel junctions\nresults in momentum filtering of the tunneling Dirac fermions, generating a\nstrong transverse valley Hall current dependent on the Dirac-cone tilting.\nUsing the parameters of an existing 2D valley material, we demonstrate that\nsuch a TVHE is much stronger than that induced by the intrinsic Berry curvature\nmechanism reported previously. Finally, we predict that resonant tunneling can\noccur in a tunnel junction with properly engineered device parameters such as\nthe spacer width and transport direction, providing significant enhancement of\nthe valley Hall angle. Our work opens a new approach to generate valley\npolarization in realistic valleytronic systems.",
        "positive": "Breakdown of counterflow superfluidity in a disordered quantum Hall\n  bilayer: We present a theory for the regime of coherent interlayer tunneling in a\ndisordered quantum Hall bilayer at total filling factor one, allowing for the\neffect of static vortices. We find that the system consists of domains of\npolarized superfluid phase. Injected currents introduce phase slips between the\npolarized domains which are pinned by disorder. We present a model of saturated\ntunneling domains that predicts a critical current for the breakdown of\ncoherent tunneling that is extensive in the system size. This theory is\nsupported by numerical results from a disordered phase model in two dimensions.\nWe also discuss how our picture might be used to interpret experiments in the\ncounterflow geometry and in two-terminal measurements."
    },
    {
        "anchor": "Probing magnetism via spin dynamics in graphene/2D-ferromagnet\n  heterostructures: The recent discovery of two-dimensional magnetic insulators has generated a\ngreat deal of excitement over their potential for nanoscale manipulation of\nspin or magnetism. One intriguing use for these materials is to put them in\ncontact with graphene, with the goal of making graphene magnetic while\nmaintaining its unique electronic properties. Such a system could prove useful\nin applications such as magnetic memories, or could serve as a host for exotic\nstates of matter. Proximity to a magnetic insulator will alter the spin\ntransport properties of graphene, and the strength of this interaction can be\nprobed with Hanle spin precession experiments. To aid in the analysis of such\nexperiments, in this work we derive an explicit expression for Hanle spin\nprecession in graphene interfaced with a ferromagnetic insulator whose\nmagnetization points perpendicular to the graphene plane. We find that this\ninterface results in a shifted and asymmetric Hanle response, and we discuss\nhow this behavior can be used to interpret measurements of spin transport in\nthese systems.",
        "positive": "A topological Dirac-vortex parametric phonon laser: Nonlinear topological photonic and phononic systems have recently aroused\nintense interests in exploring new phenomena that have no counterparts in\nelectronic systems. The squeezed bosonic interaction in these systems is\nparticularly interesting, because it can modify the vacuum fluctuations of\ntopological states, drive them into instabilities, and lead to topological\nparametric lasers. However, these phenomena remain experimentally elusive\nbecause of limited nonlinearities in most existing topological bosonic systems.\nHere, we experimentally realized topological parametric lasers based on\nnonlinear nanoelectromechanical Dirac-vortex cavities with strong squeezed\ninteraction. Specifically, we parametrically drove the Dirac-vortex cavities to\nprovide phase-sensitive amplification for topological phonons, and observed\nphonon lasing above the threshold. Additionally, we confirmed that the lasing\nfrequency is robust against fabrication disorders and that the free spectral\nrange defies the universal inverse scaling law with increased cavity size,\nwhich benefit the realization of large-area single-mode lasers. Our results\nrepresent an important advance in experimental investigations of topological\nphysics with large bosonic nonlinearities and parametric gain."
    },
    {
        "anchor": "Screening in gated bilayer graphene: The tight-binding model of a graphene bilayer is used to find the gap between\nthe conduction and valence bands, as a function of both the gate voltage and as\nthe doping by donors or acceptors. The total Hartree energy is minimized and\nthe equation for the gap is obtained. This equation for the ratio of the gap to\nthe chemical potential is determined only by the screening constant. Thus the\ngap is strictly proportional to the gate voltage or the carrier concentration\nin the absence of donors or acceptors. In the opposite case, where the donors\nor acceptors are present, the gap demonstrates the asymmetrical behavior on the\nelectron and hole sides of the gate bias.",
        "positive": "Memory effects in adiabatic quantum pumping with parasitic nonlinear\n  dynamics: The charge current adiabatically pumped through a mesoscopic region coupled\nto a classical variable obeying a nonlinear dynamics is studied within the\nscattering matrix approach. Due to the nonlinearity in the dynamics of the\nvariable, a hysteretic behavior of the pumping current can be observed for\nspecific characteristics of the pumping cycle. The steps needed to build a\nquantum pump working as a memory device are discussed together with a possible\nexperimental implementation."
    },
    {
        "anchor": "Crossover from interaction induced localization to delocalization in\n  disordered electron systems: We numerically investigate the transport properties of interacting spinless\nelectrons in disordered systems. We use an efficient method which is based on\nthe diagonalization of the Hamiltonian in the subspace of the many-particle\nHilbert space which is spanned by the low-energy Slater states. Low-energy\nproperties can be calculated with an accuracy comparable to that of exact\ndiagonalization but for larger system sizes. The method works well in the\nentire parameter space, and it can handle long-range as well as short-range\ninteractions. Using this method we calculate the combined effect of disorder\nand interactions on the Kubo-Greenwood conductance and on the sensitivity of\nthe ground state energy to a twist in the boundary conditions. We find that the\ninfluence of the interactions on the transport properties is opposite for large\nand small disorder. In the strongly localized regime (small kinetic energy,\nlarge disorder) interactions increase the transport whereas for weak disorder\n(large kinetic energy) interactions decrease the transport.",
        "positive": "Shot Noise Suppression and Hopping Conduction in Graphene Nanoribbons: We have investigated shot noise and conduction of graphene field effect\nnanoribbon devices at low temperature. By analyzing the exponential $I-V$\ncharacteristics of our devices in the transport gap region, we found out that\ntransport follows variable range hopping laws at intermediate bias voltages $1\n< V_{bias} < 12$ mV. In parallel, we observe a strong shot noise suppression\nleading to very low Fano factors. The strong suppression of shot noise is\nconsistent with inelastic hopping, in crossover from one- to two-dimensional\nregime, indicating that the localization length $l_{loc} < W$ in our\nnanoribbons."
    },
    {
        "anchor": "High-order topological insulators from high-dimensional Chern insulators: Topological insulators are a novel state of matter that share a common\nfeature: their spectral bands are associated with a nonlocal integer-valued\nindex, commonly manifesting through quantized bulk phenomena and robust\nboundary effects. In this work, we demonstrate using dimensional reduction that\nhigh-order topological insulators are descendants from a chiral semimetal in\nhigher dimensions. Specifically, we analyze the descendants of an ancestor\nfour-dimensional Chern insulator in the limit where it becomes chiral and show\ntheir relation to two-dimensional second-order topological insulators.\nCorrespondingly, the quantization of the charge accumulation at the corners of\nthe 2D descendants is obtained and related to the topological indices -- the\n1st and 2nd Chern numbers -- of the ancestor model. Our approach provides a\nconnection between the boundary states of high-order topological insulators and\ntopological pumps -- the latter being dynamical realizations of\nhigh-dimensional Chern insulators.",
        "positive": "Energy scaling law for nanostructured materials: The equilibrium binding energy is an important factor in the design of\nmaterials and devices. However, it presents great computational challenges for\nmaterials built up from nanostructures. Here we investigate the binding-energy\nscaling law from first-principles calculations. We show that the equilibrium\nbinding energy per atom between identical nanostructures can scale up or down\nwith nanostructure size. From the energy scaling law, we predict finite\nlarge-size limits of binding energy per atom. We find that there are two\ncompeting factors in the determination of the binding energy: Nonadditivities\nof van der Waals coefficients and center-to-center distance between\nnanostructures. To uncode the detail, the nonadditivity of the static multipole\npolarizability is investigated. We find that the higher-order multipole\npolarizability displays ultra-strong intrinsic nonadditivity, no matter if the\ndipole polarizability is additive or not."
    },
    {
        "anchor": "Detection of interaction-induced nonlocal effects using perfectly\n  transmitting nanostructures: We consider one-dimensional transport through an interacting region in series\nwith a point-like one-body scatterer. When the conductance of the interacting\nregion is perfect, independently of the interaction strength, a nonlocal\ninteraction effect yields a total conductance of the composed system that\ndepends on the interaction strength and is lower than the transmission of the\none-body scatterer. This qualitative nonlocal effect allows to probe the\ndressing cloud of an interacting system by ideal noninteracting leads. The\nconductance correction increases with the strength of the interaction and the\nreflection of the one-body scatterer (attaining relative changes >50%), and\ndecreases with the distance between the interacting region and the one-body\nscatterer. Scaling laws are obtained and possible experimental realizations are\nsuggested.",
        "positive": "Controllable CVD-Growth of 2D Cr5Te8 Nanosheets with Thickness-Dependent\n  Magnetic Domains: As a typical 2D magnetic material with self-intercalated structure, Cr5Te8\nexhibits many fascinating magnetic properties. Although the ferromagnetism of\n2D Cr5Te8 has been reported, the study of its magnetic domain is still blank.\nHerein, we successfully fabricated 2D Cr5Te8 nanosheets with controlled\nthickness and lateral size by chemical vapor deposition (CVD). Then magnetic\nproperty measurement system suggested Cr5Te8 nanosheets possessing intense\nout-of-plane ferromagnetism with the Curie temperature of 179 K. Most\nimportantly, we found magnetic bubbles and thickness-dependent maze-like\nmagnetic domains by cryogenic magnetic force microscopy (MFM) for the first\ntime. The domain width of the maze-like magnetic domains increases rapidly with\ndecreasing sample thickness, while domain contrast decreases. This indicates\ndipolar interaction is the dominant role over exchange interaction and magnetic\nanisotropy. Our work not only paves a way for the controllable growth of 2D\nmagnetic materials, but also suggests new directions for controlling magnetic\nphases and systematically adjusting domain properties."
    },
    {
        "anchor": "The temperature dependence of quantum spin pumping generated using\n  electron spin resonance with three-magnon splittings: On the basis of the Schwinger-Keldysh formalism, we have closely investigated\nthe temperature dependence of quantum spin pumping by electron spin resonance.\nWe have clarified that three-magnon splittings excite non-zero modes of magnons\nand characterize the temperature dependence of quantum spin pumping. Our\ntheoretical result qualitatively agrees with the experiment by Czeschka et al.\nthat the mixing conductance is little influenced by temperature [F. D. Czeschka\net al., Phys. Rev. Lett., 107, 046601 (2011)].",
        "positive": "Quasiballistic Heat Conduction in Transient Grating Spectroscopy: Transient grating (TG) spectroscopy is an important experimental technique to\nmeasure mean free path (MFP) spectra using observations of quasiballistic heat\nconduction. To obtain MFP spectra, the measurements must be interpreted within\nthe framework of the frequency-dependent Boltzmann transport equation (BTE),\nbut previous solutions have restricted validity due to simplifying assumptions.\nHere, we analyze heat conduction in TG using a new analytical solution of the\nfrequency-dependent BTE that accurately describes thermal transport from the\ndiffusive to ballistic regimes. We demonstrate that our result enables a more\naccurate measurement of MFP spectra and thus will lead to an improved\nunderstanding of heat conduction in solids."
    },
    {
        "anchor": "Satellite structures in the spectral functions of semiconductor quantum\n  well two-dimensional electron gases: a GW plus cumulant study: We present theoretical calculations for the spectral functions and\nsingle-particle densities of states of the two-dimensional electron gas in\nsemiconductor quantum wells at different electron densities using the\nGW+cumulant method. We compare our results to GW only calculations and find\nsignificant differences in the description of the satellites between the two\ntheories: while GW theory predicts the existence of a plasmaron excitation, no\nsuch excitation is found in GW+cumulant theory. We compare our results to\nexperimental tunneling spectra from semiconductor quantum wells and find good\nagreement for the satellite properties.",
        "positive": "Zener tunneling in the electrical transport of quasi-metallic carbon\n  nanotubes: We study theoretically the impact of Zener tunneling on the charge-transport\nproperties of quasi-metallic (Qm) carbon nanotubes (characterized by forbidden\nband gaps of few tens of meV). We also analyze the interplay between Zener\ntunneling and elastic scattering on defects. To this purpose we use a model\nbased on the master equation for the density matrix, that takes into account\nthe inter-band Zener transitions induced by the electric field (a quantum\nmechanical effect), the electron-defect scattering and the electron-phonon\nscattering. In presence of Zener tunnelling the Qm tubes support an electrical\ncurrent even when the Fermi energy lies in the forbidden band gap. In absence\nof elastic scattering (in high quality samples), the small size of the band gap\nof Qm tubes enables Zener tunnelling for realistic values of the the electric\nfield (above $\\sim$ 1 V/\\mu m). The presence of a strong elastic scattering (in\nlow quality samples) further decreases the values of the field required to\nobserve Zener tunnelling. Indeed, for elastic-scattering lengths of the order\nof 50 nm, Zener tunnelling affects the current/voltage characteristic already\nin the linear regime. In other words, in quasi-metallic tubes, Zener tunneling\nis made more visible by defects."
    },
    {
        "anchor": "Optical conductivity of a 2DEG with anisotropic Rashba interaction at\n  the interface of LaAlO$_3$/SrTiO$_3$: We study optical conductivity of a two-dimensional electron gas with\nanisotropic $k$-cubic Rashba spin-orbit interaction formed at the\nLaAlO$_3$/SrTiO$_3$ interface. The anisotropic spin splitting energy gives rise\nto different features of the optical conductivity in comparison to the\nisotropic $k$-cubic Rashba spin-orbit interaction. For large carrier density\nand strong spin-orbit couplings, the density dependence of Drude weight\ndeviates from the linear behavior. The charge and optical conductivities remain\nisotropic despite anisotropic nature of the Fermi contours. An infinitesimally\nsmall photon energy would suffice to initiate inter-band optical transitions\ndue to degeneracy along certain directions in momentum space. The optical\nconductivity shows a single peak at a given photon energy depending on the\nsystem parameters and then falls off to zero at higher photon energy. These\nfeatures are lacking for systems with isotropic $k$-cubic Rashba spin-orbit\ncoupling. These striking features can be used to extract the information about\nnature of the spin-orbit interaction experimentally and illuminate some light\non the orbital origin of the two-dimensional electron gas.",
        "positive": "Magnetic phases in the one-dimensional Kondo chain on a metallic surface: We study the low-temperature properties of a one-dimensional spin-1/2 chain\nof magnetic impurities coupled to a (normal) metal environment by means of\nanisotropic Kondo exchange. In the case of easy-plane anisotropy, we obtain the\nphase diagram of this system at T=0. We show that the in-plane Kondo coupling\ndestabilizes the Tomonaga-Luttinger phase of the spin-chain, and leads to two\ndifferent phases: i) At strong Kondo coupling, the spins in the chain form\nKondo singlets and become screened by the metallic environment, and ii) At weak\nand intermediate Kondo coupling, we find a novel dissipative phase\ncharacterized by diffusive gapless spin excitations. The two phases are\nseparated by a quantum critical point of the Wilson-Fisher universality class\nwith dynamical exponent $z\\simeq2$."
    },
    {
        "anchor": "Spin tunnelling in mesoscopic systems: We study spin tunnelling in molecular magnets as an instance of a mesoscopic\nphenomenon, with special emphasis on the molecule Fe8. We show that the tunnel\nsplitting between various pairs of Zeeman levels in this molecule oscillates as\na function of applied magnetic field, vanishing completely at special points in\nthe space of magnetic fields, known as diabolical points. This phenomena is\nexplained in terms of two approaches, one based on spin-coherent-state path\nintegrals, and the other on a generalization of the phase integral (or WKB)\nmethod to difference equations. Explicit formulas for the diabolical points are\nobtained for a model Hamiltonian.",
        "positive": "Possible phason-polaron effect on purely one dimensional charge order of\n  Mo6Se6 nanowires: In one-dimensional (1D) metallic systems, the diverging electron\nsusceptibility and electron-phonon coupling collaboratively drive the electrons\ninto a charge density wave (CDW) state. However, strictly 1D system is unstable\nagainst perturbations, whose effect on CDW order requires clarification ideally\nwith altered coupling to surroundings. Here, we fabricate such a system with\nnanowires of Mo6Se6 bundles, which are either attached to edges of monolayer\nMoSe2 or isolated freely, by post-annealing the preformed MoSe2. Using scanning\ntunneling microscopy (STM), we visualized charge modulations and CDW gaps with\nprominent coherent peaks in the edge-attached nanowires. Astonishingly, the CDW\norder becomes suppressed in the isolated nanowires, showing CDW correlation\ngaps without coherent peaks. The contrasting behavior, as revealed with\ntheoretical modeling, is interpreted as the effect of phason-polarons on the 1D\nCDW state. Our work elucidates a possibly unprecedented many body effect that\nmay be generic to strictly 1D system but undermined in quasi-1D system."
    },
    {
        "anchor": "Enhancement of Diffusive Transport by Nonequilibrium Thermal\n  Fluctuations: We study the contribution of advection by thermal velocity fluctuations to\nthe effective diffusion coefficient in a mixture of two identical fluids. The\nsteady-state diffusive flux in a finite system subject to a concentration\ngradient is enhanced because of long-range correlations between concentration\nfluctuations and fluctuations of the velocity parallel to the concentration\ngradient. The enhancement of the diffusive transport depends on the system size\nL and grows as \\ln(L/L_{0}) in quasi-two dimensional systems, while in three\ndimensions it grows as L_{0}^{-1}-L^{-1}, where L_{0} is a reference length.\nThe predictions of a simple fluctuating hydrodynamics theory, closely related\nto second-order mode-mode coupling analysis, are compared to results from\nparticle simulations and a finite-volume solver and excellent agreement is\nobserved. We elucidate the direct connection to the long-time tail of the\nvelocity autocorrelation function in finite systems, as well as finite-size\ncorrections employed in molecular dynamics calculations. Our results\nconclusively demonstrate that the nonlinear advective terms need to be retained\nin the equations of fluctuating hydrodynamics when modeling transport in\nsmall-scale finite systems.",
        "positive": "Coherent electron trajectory control in graphene: We investigate coherent electron dynamics in graphene, interacting with the\nelectric field waveform of two orthogonally polarized, few-cycle laser pulses.\nRecently, we demonstrated that linearly polarized driving pulses lead to\nsub-optical-cycle Landau-Zener quantum path interference by virtue of the\ncombination of intraband motion and interband transition [Higuchi $\\textit{et\nal.}$, Nature $\\textbf{550}$, 224 (2017)]. Here we introduce a pulsed control\nlaser beam, orthogonally polarized to the driving pulses, and observe the\nensuing electron dynamics. The relative delay between the two pulses is a\ntuning parameter to control the electron trajectory, now in a complex fashion\nexploring the full two-dimensional reciprocal space in graphene. Depending on\nthe relative phase, the electron trajectory in the reciprocal space can, for\nexample, be deformed to suppress the quantum path interference resulting from\nthe driving laser pulse. Intriguingly, this strong-field-based complex matter\nwave manipulation in a two-dimensional conductor is driven by a high repetition\nrate \\textit{laser oscillator}, rendering unnecessary complex and expensive\namplified laser systems."
    },
    {
        "anchor": "Importance of individual scattering matrix elements at Fano resonances: Single particle resonances in quantum wires are generally Fano resonances. In\ncase of Fano resonances, the scattering phase shift in some channels show sharp\nphase drops and that in the other channels do not. Phase shift in a particular\nchannel can be measured and can yield information about the integrated charge\nlocalized around the scatterer. This paper tries to analyze if some channels\nare more informative than the others, so that an experimentalist can measure\nthe phase shift in only those channels.",
        "positive": "New applications of non-hermitian random matrices: We discuss recently discovered links of the statistical models of normal\nrandom matrices to some important physical problems of pattern formation and to\nthe quantum Hall effect. Specifically, the large $N$ limit of the normal matrix\nmodel with a general statistical weight describes dynamics of the interface\nbetween two incompressible fluids with different viscousities in a thin plane\ncell (the Saffman-Taylor problem). The latter appears to be mathematically\nequivalent to the growth of semiclassical 2D electronic droplets in a strong\nuniform magnetic field with localized magnetic impurities (fluxes), as the\nnumber of electrons increases. The equivalence is most easily seen by relating\nthe both problems to the matrix model."
    },
    {
        "anchor": "Spin qubit manipulation of acceptor bound states in group IV quantum\n  wells: The large spin-orbit coupling in the valence band of group IV semiconductors\nprovides an electric field knob for spin-qubit manipulation. This fact can be\nexploited with acceptor based qubits. Spin manipulation of holes bound to\nacceptors in engineered SiGe quantum wells depends very strongly on the\nelectric field applied and on the heterostructure parameters. The g-factor is\nenhanced by the Ge content and can be tuned by shifting the hole wave-function\nbetween the heterostructure constituent layers. The lack of inversion symmetry\ninduced both by the quantum well and the electric fields together with the\ng-factor tunability allows the possibility of different qubit manipulation\nmethods such as electron spin resonance, electric dipole spin resonance and\ng-tensor modulation resonance. Rabi frequencies up to hundreds of MHz can be\nachieved with heavy-hole qubits, and of the order of GHz with light-hole\nqubits.",
        "positive": "Conditional relaxation of a charge state under continuous weak\n  measurement: We investigate the conditional evolution of a charge state coupled to a\nmesoscopic detector under continuous weak measurement. The state suffers\nrelaxation into a particular state with a definite charge when electrons in a\nparticular output lead are monitored in the detector. The process of the\nconditional relaxation is not restricted by the shot noise of the detector,\nunlike the case of the back-action dephasing. As a result, the relaxation of\nconditional evolution is much faster than the current-sensitive part of\ndephasing. Furthermore, the direction of the relaxation depends on the choice\nof the output lead. We propose that these properties can be verified in a\ntwo-path interferometer containing a quantum dot capacitively coupled to a\ndetector. In this setup, the current-current correlation between the\ninterferometer and the detector reveals characteristic features of conditional\nrelaxation."
    },
    {
        "anchor": "High harmonic generation in triangular graphene quantum dots: Higher harmonic generation in plane graphene quantum dots initiated by\nintense coherent radiation is investigated, using dynamical Hartree-Fock\nmean-field theory. A microscopic theory describing the extreme nonlinear\noptical response of plane graphene quantum dots is developed. The closed set of\ndifferential equations for the single-particle density matrix at the graphene\nquantum dots-strong laser field multiphoton interaction is solved numerically.\nThe obtained solutions indicate the significance of the type of edge and\nlateral size, and bandgap and laser field strength in the high harmonic\ngeneration process on the triangular graphene quantum dot.",
        "positive": "Field effect two-dimensional electron gases in modulation-doped InSb\n  surface quantum wells: We report on transport characteristics of field effect two-dimensional\nelectron gases (2DEG) in surface indium antimonide quantum wells. The topmost 5\nnm of the 30 nm wide quantum well is doped and shown to promote the formation\nof reliable, low resistance Ohmic contacts to surface InSb 2DEGs. High quality\nsingle-subband magnetotransport with clear quantized integer quantum Hall\nplateaus are observed to filling factor $\\nu=1$ in magnetic fields of up to\n$B=18$ T. We show that the electron density is gate-tunable, reproducible, and\nstable from pinch-off to 4$\\times 10^{11}$ cm$^{-2}$, and peak mobilities\nexceed 24,000 cm$^2$/Vs. Large Rashba spin-orbit coefficients up to 110\nmeV$\\cdot$\\r{A} are obtained through weak anti-localization measurements. An\neffective mass of 0.019$m_e$ is determined from temperature-dependent\nmagnetoresistance measurements, and a g-factor of 41 at a density of 3.6$\\times\n10^{11}$ cm$^{-2}$ is obtained from coincidence measurements in tilted magnetic\nfields. By comparing two heterostructures with and without a delta-doped layer\nbeneath the quantum well, we find that the carrier density is stable with time\nwhen doping in the ternary Al$_{0.1}$In$_{0.9}$Sb barrier is not present.\nFinally, the effect of modulation doping on structural asymmetry between the\ntwo heterostructures is characterized."
    },
    {
        "anchor": "Theory of plasmonic edge states in chiral bilayer systems: We analytically describe the plasmonic edge modes for an interface that\ninvolves the twisted bilayer graphene (TBG) or other similar Moire van der\nWaals heterostructure. For this purpose, we employ a spatially homogeneous,\nisotropic and frequency-dependent tensor conductivity which in principle\naccounts for electronic and electrostatic interlayer couplings. We predict that\nthe edge mode dispersion relation explicitly depends on the chiral response\neven in the nonretarded limit, in contrast to the collective bulk plasmonic\nexcitations in the TBG. We obtain a universal function for the dispersion of\nthe optical edge plasmon in the paramagnetic regime. This implies a\ncorrespondence of the chiral-TBG optical plasmon to a magnetoplasmon of a\nsingle sheet, and chirality is interpreted as an effective magnetic field. The\nchirality also opens up the possibility of nearly undamped acoustic modes in\nthe paramagnetic regime. Our results may guide future near-field nanoscopy for\nvan der Waals heterostructures. In our analysis, we retain the long-range\nelectrostatic interaction, and apply the Wiener-Hopf method to a system of\nintegral equations for the scalar potentials of the two layers.",
        "positive": "Evidence for spin-flip scattering and local moments in dilute\n  fluorinated graphene: The issue of whether local magnetic moments can be formed by introducing\nadatoms into graphene is of intense research interest because it opens the\nwindow to fundamental studies of magnetism in graphene, as well as of its\npotential spintronics applications. To investigate this question we measure, by\nexploiting the well-established weak localization physics, the phase coherence\nlength L_phi in dilute fluorinated graphene. L_phi reveals an unusual\nsaturation below ~ 10 K, which cannot be explained by non-magnetic origins. The\ncorresponding phase breaking rate increases with decreasing carrier density and\nincreases with increasing fluorine density. These results provide strong\nevidence for spin-flip scattering and points to the existence of adatom-induced\nlocal magnetic moment in fluorinated graphene. Our results will stimulate\nfurther investigations of magnetism and spintronics applications in\nadatom-engineered graphene."
    },
    {
        "anchor": "Dynamic Error in Strain Induced Magnetization Reversal of Nanomagnets\n  due to Incoherent Switching and Formation of Metastable States: A\n  Size-dependent Study: Modulation of stress anisotropy of magnetostrictive nanomagnets with strain\noffers an extremely energy-efficient method of magnetization reversal. The\nreversal process, however, is often incoherent and hence error-prone in the\npresence of thermal noise at room temperature. Occurrence of incoherent\nmetastable states in the potential landscape of the nanomagnet can further\nexacerbate the error. Stochastic micromagnetic simulations at room temperature\nare used to understand and calculate energy dissipations and switching error\nprobabilities in this important magnetization switching methodology. We find\nthat these quantities have an intriguing dependence on nanomagnet size: small\nnanomagnets perform better owing to the fact that they are more resilient to\nthe formation of metastable states and magnetization dynamics in them is more\ncoherent. However, for a fixed stress anisotropy energy density, smaller\nnanomagnets will also have poorer resilience against thermal instability. Thus,\nthe challenge in straintronics is to maximize the stress anisotropy energy\ndensity by developing materials and processes that yield the largest\nmagnetostriction.",
        "positive": "Characterization of S-T$_+$ Transition Dynamics via Correlation\n  Measurements: Nuclear spins are an important source of dephasing for electron spin qubits\nin GaAs quantum dots. Most studies of their dynamics have focused on the\nrelatively slow longitudinal polarization. We show, based on a semiclassical\nmodel and experimentally, that the dynamics of the transverse hyperfine field\ncan be probed by correlating individual Landau-Zener sweeps across the S-T$_+$\ntransition of a two-electron spin qubit. The relative Larmor precession of\ndifferent nuclear spin species leads to oscillations in these correlations,\nwhose decay arises from dephasing of the nuclei. In the presence of spin orbit\ncoupling, oscillations with the absolute Larmor frequencies whose amplitude\nreflects the spin orbit coupling strength are expected."
    },
    {
        "anchor": "Surface plasmons on a thin film topological insulator: Recently it has been shown that surface plasmons supported by an interface\nbetween a 3+1 dimensional topological insulator and a metal or between a 3+1\ndimensional topological insulator with residual bulk charge carriers and vacuum\nhave a polarization that is rotated by an angle of order of the fine structure\nconstant alpha compared to their topological trivial counterparts. In this work\nwe generalize this analysis to the more realistic case of thin films, taking\ninto account the effect of multiple reflections. In the symmetric case of a\nthin film surrounded by the same material on both sides the polarization of\nboth allowed surface plasmon modes is unchanged from the single interface case,\neven though their dispersion relation is altered by the interactions between\nthe two surface layers. In the general asymmetric case the angle is affected as\nwell. We give a simple analytic expression for the resonance condition that\ndetermines the angle and solve it perturbatively for the case of a thin film\nbetween two media with almost identical permittivity.",
        "positive": "Analytical study of the edge states in the bosonic Haldane model: We investigate the properties of magnon edge states in a ferromagnetic\nhoneycomb spin lattice with a Dzyaloshinskii-Moriya interaction (DMI). We\nderive analytical expressions for the energy spectra and wavefunctions of the\nedge states localized on the boundaries. By introducing an external on-site\npotential at the outermost sites, we show that the bosonic band structure is\nsimilar to that of the fermionic graphene. We investigate the region in the\nmomentum space where the bosonic edge states are well defined and we analyze\nthe width of the edge state and their dependence with DMI strength. Our\nfindings extend the predictions using topological arguments and they allow\nsize-dependent confirmation from possible experiments"
    },
    {
        "anchor": "Transport properties of quantum dots in the Wigner molecule regime: The transport properties of quantum dots with up to N=7 electrons ranging\nfrom the weak to the strong interacting regime are investigated via the\nprojected Hartree-Fock technique. As interactions increase radial order\ndevelops in the dot, with the formation of ring and centered-ring structures.\nSubsequently, angular correlations appear, signalling the formation of a Wigner\nmolecule state. We show striking signatures of the emergence of Wigner\nmolecules, detected in transport. In the linear regime, conductance is\nexponentially suppressed as the interaction strength grows. A further\nsuppression is observed when centered-ring structures develop, or peculiar spin\ntextures appear. In the nonlinear regime, the formation of molecular states may\neven lead to a conductance enhancement.",
        "positive": "Bias spectroscopy and simultaneous SET charge state detection of Si:P\n  double dots: We report a detailed study of low-temperature (mK) transport properties of a\nsilicon double-dot system fabricated by phosphorous ion implantation. The\ndevice under study consists of two phosphorous nanoscale islands doped to above\nthe metal-insulator transition, separated from each other and the source and\ndrain reservoirs by nominally undoped (intrinsic) silicon tunnel barriers.\nMetallic control gates, together with an Al-AlOx single-electron transistor,\nwere positioned on the substrate surface, capacitively coupled to the buried\ndots. The individual double-dot charge states were probed using source-drain\nbias spectroscopy combined with non-invasive SET charge sensing. The system was\nmeasured in linear (VSD = 0) and non-linear (VSD <> 0) regimes allowing\ncalculations of the relevant capacitances. Simultaneous detection using both\nSET sensing and source-drain current measurements was demonstrated, providing a\nvaluable combination for the analysis of the system. Evolution of the triple\npoints with applied bias was observed using both charge and current sensing.\nCoulomb diamonds, showing the interplay between the Coulomb charging effects of\nthe two dots, were measured using simultaneous detection and compared with\nnumerical simulations."
    },
    {
        "anchor": "Room temperature Organic Exciton-Polariton Condensate in a Lattice: Interacting Bosons, loaded in artificial lattices, have emerged as a modern\nplatform to explore collective manybody phenomena, quantum phase transitions\nand exotic phases of matter as well as to enable advanced on chip simulators.\nSuch experiments strongly rely on well-defined shaping the potential landscape\nof the Bosons, respectively Bosonic quasi-particles, and have been restricted\nto cryogenic, or even ultra-cold temperatures. On chip, the GaAs-based\nexciton-polariton platform emerged as a promising system to implement and study\nbosonic non-linear systems in lattices, yet demanding cryogenic temperatures.\nIn our work, we discuss the first experiment conducted on a polaritonic lattice\nat ambient conditions: We utilize fluorescent proteins as an excitonic gain\nmaterial, providing ultra-stable Frenkel excitons. We directly take advantage\nof their soft nature by mechanically shaping them in the photonic\none-dimensional lattice. We demonstrate controlled loading of the condensate in\ndistinct orbital lattice modes of different symmetries, and finally explore, as\nan illustrative example, the formation of a gap solitonic mode, driven by the\ninterplay of effective interaction and negative effective mass in our lattice.\nThe observed phenomena in our open dissipative system are comprehensively\nscrutinized by a nonequilibrium model of polariton condensation. We believe,\nthat this work is establishing the organic polariton platform as a serious\ncontender to the well-established GaAs platform for a wide range of\napplications relying on coherent Bosons in lattices, given its unprecedented\nflexibility, cost effectiveness and operation temperature.",
        "positive": "Josephson-Junction Qubits with Controlled Couplings: Low-capacitance Josephson junctions, where Cooper pairs tunnel coherently\nwhile Coulomb blockade effects allow the control of the total charge, provide\nphysical realizations of quantum bits (qubits), with logical states differing\nby one Cooper-pair charge on an island. The single- and two-bit operations\nrequired for quantum computation can be performed by applying a sequence of\ngate voltages. A basic design, described earlier [cond-mat/9706016], is\nsufficient to demonstrate the principles, but requires a high precision time\ncontrol, and residual two-bit interactions introduce errors. Here we suggest a\nnew nano-electronic design, close to ideal, where the Josephson junctions are\nreplaced by controllable SQUIDs. This relaxes the requirements on the time\ncontrol and system parameters substantially, and the two-bit coupling can be\nswitched exactly between zero and a non-zero value for arbitrary pairs. The\nphase coherence time is sufficiently long to allow a series of operations."
    },
    {
        "anchor": "Direct measurement of the phase coherence length in a GaAs/GaAlAs square\n  network: The low temperature magnetoconductance of a large array of quantum\ncoherentloops exhibits Altshuler-Aronov-Spivak oscillations which\nperiodicitycorresponds to 1/2 flux quantum per loop.We show that the\nmeasurement of the harmonics content in a square networkprovides an accurate\nway to determine the electron phase coherence length$L\\_{\\phi}$ in units of the\nlattice length without any adjustableparameters.We use this method to determine\n$L\\_{\\phi}$ in a network realised from a 2Delectron gas (2DEG) in a GaAS/GaAlAs\nheterojunction. The temperaturedependence follows a power law $T^{-1/3}$ from\n1.3 K to 25 mK with nosaturation, as expected for 1D diffusive electronic\nmotion andelectron-electron scattering as the main decoherence mechanism.",
        "positive": "Inelastic rotations and pseudo-turbulent plastic avalanches in crystals: Plastic deformations in crystals often produce textures in the form of\nrandomly oriented patches of the unstressed lattice. We use a novel mesoscopic\nLandau-type model of crystal plasticity to show that in such textures large\ncrystallographic lattice rotations can originate from a highly coordinated\ninelastic slip at the microscale. Our numerical experiments show that\ndislocation avalanches, which lead to the formation of such rotations, involve\npseudo-turbulent motions with power-law distributed spatial correlations."
    },
    {
        "anchor": "Three-dimensional spin-wave dynamics, localization and interference in a\n  synthetic antiferromagnet: Spin waves are collective perturbations in the orientation of the magnetic\nmoments in magnetically ordered materials. Their rich phenomenology is\nintrinsically three dimensional, from the trajectory of the spin precession\nduring their propagation, to the profiles of the spin-wave mode throughout the\nvolume of the magnetic system. This gives rise to novel complex phenomena with\nhigh potential for applications in the field of magnonics. However, the\nthree-dimensional imaging of spin waves, key to understanding and harnessing\nthese phenomena, has so far not been possible. Here, we image the\nthree-dimensional dynamics of spin waves excited in a synthetic\nantiferromagnet, with nanoscale spatial resolution and sub-ns temporal\nresolution, using time-resolved magnetic laminography. In this way, we map the\ndistribution of the spin-wave modes throughout the volume of the structure,\nrevealing unexpected depth-dependent profiles originating from the interlayer\ndipolar interaction. We experimentally demonstrate the existence of complex\nthree-dimensional interference patterns, and analyze them via micromagnetic\nmodelling. We find that these patterns are generated by the superposition of\nspin waves with non-uniform amplitude profiles, and that their features can be\ncontrolled by tuning the composition and structure of the magnetic system. Our\nresults open unforeseen possibilities for the study of complex spin-wave modes\nand their interaction within nanostructures, and for the generation and\nmanipulation of three-dimensional spin-wave landscapes for the design of novel\nfunctions in magnonic devices.",
        "positive": "Zitterbewegung, chirality, and minimal conductivity in graphene: It has been recently demonstrated experimentally that graphene, or\nsingle-layer carbon, is a gapless semiconductor with massless Dirac energy\nspectrum. A finite conductivity per channel of order of $e^{2}/h$ in the limit\nof zero temperature and zero charge carrier density is one of the striking\nfeatures of this system. Here we analyze this peculiarity based on the Kubo and\nLandauer formulas. The appearance of a finite conductivity without scattering\nis shown to be a characteristic property of Dirac chiral fermions in two\ndimensions."
    },
    {
        "anchor": "Klein tunneling through triple barrier in AB bilayer graphene: We investigate the transport properties of charge carriers in AB bilayer\ngraphene through a triple electrostatic barrier. We calculate the transmission\nand reflection using the continuity conditions at the interfaces of the triple\nbarrier together with the transfer matrix method. First, we consider the case\nwhere the energy is less than the interlayer coupling $\\gamma_1$ and show that,\nat normal incidence, transmission is completely suppressed in the gap for a\nlarge barrier width while it appears in the gap for a small barrier width. For\nenergies greater than $\\gamma_1$, we show that in the absence of an interlayer\npotential difference, transmission is less than that of a single barrier, but\nin its presence, transmission in the gap region is suppressed, as opposed to a\ndouble barrier. It is found that one, two, or three gaps can be created\ndepending on the number of interlayer potential differences applied. Resonance\nin the $T_-^+$ transmission channel is observed that is not seen in the single\nand double barrier cases. Finally, we compute the conductance and show that the\nnumber of peaks is greater than the double barrier case.",
        "positive": "Thermal excitations within and among mesospins in artificial spin ice: We provide experimental and numerical evidence for thermal excitations within\nand among magnetic mesospins, forming artificial spin ice structures. At low\ntemperatures, a decrease in magnetization and increase in susceptibility is\nobserved with increasing temperature, interpreted as an onset of thermal\nfluctuations of the magnetic texture within the mesospins. At elevated\ntemperatures a pronounced susceptibility peak is observed, related to thermally\ninduced flipping of the mesospins and a collapse of the remanent state. The\nfluctuations, while occurring at distinct length- and energy-scales, are shown\nto be tunable by the interaction strength of the mesospins."
    },
    {
        "anchor": "Controlling the synchronization properties of two dipolarly coupled\n  vortex based spin-torque nano-oscillators by the intermediate of a third one: In this paper, we propose to control the strength of phase-locking between\ntwo dipolarly coupled vortex based spin-torque nano-oscillators by placing an\nintermediate oscillator between them. We show through micromagnetic simulations\nthat the strength of phase-locking can be largely tuned by a slight variation\nof current in the intermediate oscillator. We develop simplified numerical\nsimulations based on analytical expressions of the vortex core trajectories\nthat will be useful for investigating large arrays of densely packed\nspin-torque oscillators interacting through their stray fields.",
        "positive": "Current Assisted Magnetization Switching in (Ga,Mn)As Nanodevices: Current induced magnetization switching and resistance associated with domain\nwalls pinned in nanoconstrictions have both been previously reported in\n(Ga,Mn)As based devices, but using very dissimilar experimental schemes and\ndevice geometries . Here we report on the simultaneous observation of both\neffects in a single nanodevice, which constitutes a significant step forward\ntowards the eventual realization of spintronic devices which make use of domain\nwalls to store, transport, and manipulate information."
    },
    {
        "anchor": "Controllable photo-induced spin and valley filtering in silicene: We study ballistic transport of Dirac electrons through a strip in silicene,\nwhen the strip is exposed to off-resonant circularly polarized light and an\nelectric field applied perpendicular to the silicene plane. We show that the\nconductance through the strip is spin- or/and valley-polarized. This can be\nexplained by spin-valley coupling in silicene, and modification of its band\nstructure through virtual absorption/emission processes and also by the\nperpendicular electric field. The spin- (valley-) polarization can be enhanced\nby tuning the light intensity and the value of the perpendicular electric\nfield, leading to perfect spin (valley) filtering for certain of their values.\nFurther, the spin (valley) polarization can be inverted by reversing the\nperpendicular electric field (by reversing the perpendicular electric field or\nreversing the circular polarization of the light irradiation). The conditions\nnecessary for the fully valley polarization is determined.",
        "positive": "Comment to article \"A light--hole exciton in a quantum dot\" by Y.H.Huo\n  et al, Nature Physics 10, 46 (2014): The exciton ground state in strained quantum dots similar to those fabricated\nin article specified in the title is shortly discussed within a relevant model\nHamiltonian. Some characteristics of the light--hole exciton ground state\nreached in a dot under the tensile biaxial strain appear to be sensitive to the\nstrain anisotropy breaking a purity of this state. It refers in particular to a\ndegree of the in--plane polarization of the emission and the fine structure of\nthe ground state."
    },
    {
        "anchor": "Localized Floquet states in gated bilayer graphene induced by focused\n  optical beam with orbital angular momentum: We theoretically studied the Floquet state of gated bilayer graphene, which\nis irradiated by normally incident focused Gaussian beam with orbital angular\nmomentum (OAM). According to the Floquet theory, in-plane and out-of-plane\nelectric field of the OAM beam periodically perturbs the intralayer and\ninterlayer hopping, which are equivalent to the presence of effective staggered\nsublattice potential and next-nearest neighboring interlayer hopping within the\nlight spot region, respectively. The combination of the effective terms and the\ngated voltage form an effective trapping potential, which hosts localized\nquantum states with energy level being within the energy gap of the\nnon-irradiated gated bilayer graphene. The energy spectrum can be tuned by the\namplitude of the optical beam and additional static magnetic field. By\nengineering the parameters, valley-polarized two-fold degenerated zero energy\nFloquet states can be induced.",
        "positive": "Voltage tunability of single spin-states in a quantum dot: Single spins in the solid-state offer a unique opportunity to store and\nmanipulate quantum information, and to perform quantum-enhanced sensing of\nlocal fields and charges. Optical control of these systems using techniques\ndeveloped in atomic physics has yet to exploit all the advantages of the\nsolid-state. We demonstrate voltage tunability of the spin energy levels in a\nsingle quantum dot by modifying how spins sense magnetic field. We find the\nin-plane g-factor varies discontinuously for electrons, as more holes are\nloaded onto the dot. In contrast, the in-plane hole g-factor varies\ncontinuously. The device can change the sign of the in-plane g-factor of a\nsingle hole, at which point an avoided crossing is observed in the two spin\neigenstates. This is exactly what is required for universal control of a single\nspin with a single electrical gate."
    },
    {
        "anchor": "Size dependent Acoustic Phonon Dynamics of CdTe0.68Se0.32 Nanoparticles\n  in Borosilicate glass: Low frequency acoustic vibration and phonon linewidth for CdTe0.68Se0.32\nnanoparticle embedded in borosilicate glass are calculated using two different\napproaches by considering the elastic continuum model and fixed boundary\ncondition. The presence of medium significantly affects the phonon peaks and\nresults into the broadening of the modes. The linewidth is found to depend\ninversely on the size, similar to that reported experimentally. The damping\ntime and quality factor have also been calculated. The damping time that is of\nthe order of picoseconds decreases with the decrease in size. High value of\nquality factor for l=2 normal mode suggests the less loss of energy for this\nmode.",
        "positive": "Current-induced phase transition in ballistic Ni nanocontacts: Local phase transition from ferromagnetic to paramagnetic state in the region\nof the ballistic Ni nanocontacts (NCs) has been experimentally observed. We\nfound that contact size reduction leads to an increase in the bias voltage at\nwhich the local phase transition occurs. Presented theoretical interpretation\nof this phenomena takes into the account the specificity of the local heating\nof the ballistic NC and describes the electron's energy relaxation dependences\non the applied voltage. The experimental data are in good qualitative and\nquantitative agreement with the theory proposed."
    },
    {
        "anchor": "Electron quantum optics in quantum Hall edge channels: In this paper, we review recent developments in the emerging field of\nelectron quantum optics, stressing analogies and differences with the usual\ncase of photon quantum optics. Electron quantum optics aims at preparing,\nmanipulating and measuring coherent single electron excitations propagating in\nballistic conductors such as the edge channels of a 2DEG in the integer quantum\nHall regime. Because of the Fermi statistics and the presence of strong\ninteractions, electron quantum optics exhibits new features compared to the\nusual case of photon quantum optics. In particular, it provides a natural\nplayground to understand decoherence and relaxation effects in quantum\ntransport.",
        "positive": "External Bias Dependent Direct To Indirect Bandgap Transition in\n  Graphene Nanoribbon: In this work, using self-consistent tight-binding calculations, for the first\ntime, we show that a direct to indirect bandgap transition is possible in an\narmchair graphene nanoribbon by the application of an external bias along the\nwidth of the ribbon, opening up the possibility of new device applications.\nWith the help of Dirac equation, we qualitatively explain this bandgap\ntransition using the asymmetry in the spatial distribution of the perturbation\npotential produced inside the nanoribbon by the external bias. This is followed\nby the verification of the bandgap trends with a numerical technique using\nMagnus expansion of matrix exponentials. Finally, we show that the carrier\neffective masses possess tunable sharp characters in the vicinity of the\nbandgap transition points."
    },
    {
        "anchor": "Chiral Majorana Interference as a Source of Quantum Entanglement: Interferometry is a powerful tool for entanglement production and detection\nin multiterminal mesoscopic systems. Here we propose a setup to produce,\nmanipulate and detect entanglement in the electron-hole degree of freedom by\nexploiting Andreev reflection on chiral one-dimensional channels via\ninterferometry. We study the best possible case in which two-particle\ninterferometry produces superpositions of maximally entangled states. This is\nachieved by mixing chiral Dirac channels through chiral Majorana modes. We show\nthat it is possible to extract entanglement witnesses through current\ncross-correlation measurements.",
        "positive": "Floquet control of dipolaritons in quantum wells: We developed the theory of dipolaritons in semiconductor quantum wells\nirradiated by an off-resonant electromagnetic wave (dressing field). Solving\nthe Floquet problem for the dressed dipolaritons, we demonstrated that the\nfield drastically modifies all dipolaritonic properties. In particular, the\ndressing field strongly effects on terahertz emission from the considered\nsystem. The described effect paves the way for optical control of prospective\ndipolariton-based terahertz devices."
    },
    {
        "anchor": "Quantum mechanics of composite fermions: We establish the quantum mechanics of composite fermions based on the dipole\npicture initially proposed by Read. It comprises three complimentary\ncomponents: a wave equation for determining the wave functions of a composite\nfermion in ideal fractional quantum Hall states and when subjected to external\nperturbations, a wave function ansatz for mapping a many-body wave function of\ncomposite fermions to a physical wave function of electrons, and a microscopic\napproach for determining the effective Hamiltonian of the composite fermion.\nThe wave equation resembles the ordinary Schr\\\"{o}dinger equation but has drift\nvelocity corrections which are not present in the Halperin-Lee-Read theory. The\nwave-function ansatz constructs a physical wave function of electrons by\nprojecting a state of composite fermions onto a half-filled bosonic Laughlin\nstate of vortices. Remarkably, Jain's wave function ansatz can be reinterpreted\nas the new ansatz in an alternative wave-function representation of composite\nfermions. The dipole model and the effective Hamiltonian can be derived from\nthe microscopic model of interacting electrons confined in a Landau level, with\nparameters fully determined. In this framework, we can construct the physical\nwave function of a fractional quantum Hall state deductively by solving the\nwave equation and applying the wave function ansatz, based on the effective\nHamiltonian derived from first principles, rather than relying on intuitions or\neducated guesses. For ideal fractional quantum Hall states in the lowest Landau\nlevel, the approach yields physical wave functions identical to those\nprescribed by the standard theory of composite fermions. We further demonstrate\nthat the reformulated theory of composite fermions can be easily generalized\nfor flat Chern bands.",
        "positive": "Excess Kondo resonance in a quantum dot device with normal and\n  superconducting leads: the physics of Andreev-normal co-tunneling: We report on a novel Kondo phenomenon of interacting quantum dots coupled\nasymmetrically to a normal and a superconducting lead. The effects of intradot\nCoulomb interaction and Andreev tunneling give rise to Andreev bound\nresonances. As a result, a new type of co-tunneling process which we term\nAndreev-normal co-tunneling, is predicted. At low temperatures, coherent\nsuperposition of these co-tunneling processes induces a Kondo effect in which\nCooper pairs directly participate formation of a spin singlet, leading to four\nKondo resonance peaks in the local density of states, and enhancing the\ntunneling current."
    },
    {
        "anchor": "Transport signatures of Floquet Majorana fermions in driven topological\n  superconductors: Floquet Majorana fermions are steady states of equal superposition of\nelectrons and holes in a periodically driven superconductor. We study the\nexperimental signatures of Floquet Majorana fermions in transport measurements\nand show, both analytically and numerically, that their presence is signaled by\na quantized conductance sum rule over discrete values of lead bias differing by\nmultiple absorption or emission energies at drive frequency. We also study the\neffects of static disorder and find that the quantized sum rule is robust\nagainst weak disorder. Thus, we offer a unique way to identify the topological\nsignatures of Floquet Majorana fermions.",
        "positive": "A Perspective on Magnon Spin Nernst Effect in Antiferromagnets: Magnon excitations in antiferromagnetic materials and their physical\nimplications enable novel device concepts not available in ferromagnets,\nemerging as a new area of active research. A unique characteristic of\nantiferromagnetic magnons is the coexistence of opposite spin polarization,\nwhich mimics the electron spin in a variety of transport phenomena. Among them,\nthe most prominent spin-contrasting phenomenon is the magnon spin Nernst effect\n(SNE), which refers to the generation of transverse pure magnon spin current\nthrough a longitudinal temperature gradient. We introduce selected recent\nprogress in the study of magnon SNE in collinear antiferromagnets with a focus\non its underlying physical mechanism entailing profound topological features of\nthe magnon band structures. By reviewing how the magnon SNE has inspired and\nenriched the exploration of topological magnons, we offer our perspectives on\nthis emerging frontier that holds potential in future spintronic\nnano-technology."
    },
    {
        "anchor": "Longitudinal spin-relaxation of donor-bound electrons in direct bandgap\n  semiconductors: We measure the donor-bound electron longitudinal spin-relaxation time ($T_1$)\nas a function of magnetic field ($B$) in three high-purity direct-bandgap\nsemiconductors: GaAs, InP, and CdTe, observing a maximum $T_1$ of\n$1.4~\\text{ms}$, $0.4~\\text{ms}$ and $1.2~\\text{ms}$, respectively. In GaAs and\nInP at low magnetic field, up to $\\sim2~\\text{T}$, the spin-relaxation\nmechanism is strongly density and temperature dependent and is attributed to\nthe random precession of the electron spin in hyperfine fields caused by the\nlattice nuclear spins. In all three semiconductors at high magnetic field, we\nobserve a power-law dependence ${T_1 \\propto B^{-\\nu}}$ with ${3\\lesssim \\nu\n\\lesssim 4}$. Our theory predicts that the direct spin-phonon interaction is\nimportant in all three materials in this regime in contrast to quantum dot\nstructures. In addition, the \"admixture\" mechanism caused by Dresselhaus\nspin-orbit coupling combined with single-phonon processes has a comparable\ncontribution in GaAs. We find excellent agreement between high-field theory and\nexperiment for GaAs and CdTe with no free parameters, however a significant\ndiscrepancy exists for InP.",
        "positive": "Giant Rabi splitting in metallic cluster-cavity system: We investigate theoretically the photo absorbtion of the cluster of alkali\natoms embedded into a single mode quantum microcavity. We show that when the\nenergy of the giant plasmonic resonance lies close to the energy of the cavity\nmode, the strong coupling between plasmon and cavity photon can occur, which is\ncharacterized by mode anticrossing and observation of the doublet structure in\nptotoabsorbtion. The characteristic values of the Rabi splitting are expected\nto be several orders of magnitude larger then those observed in single quantum\ndot-cavity systems."
    },
    {
        "anchor": "Understanding Variations in Circularly Polarized Photoluminescence in\n  Monolayer Transition Metal Dichalcogenides: Monolayer transition metal dichalcogenides are promising materials for\nvalleytronic operations. They exhibit two inequivalent valleys in the Brillouin\nzone, and the valley populations can be directly controlled and determined\nusing circularly polarized optical excitation and emission. The\nphotoluminescence polarization reflects the ratio of the two valley\npopulations. A wide range of values for the degree of circularly polarized\nemission, Pcirc, has been reported for monolayer WS2, although the reasons for\nthe disparity are unclear. Here we optically populate one valley, and measure\nPcirc to explore the valley population dynamics at room temperature in a large\nnumber of monolayer WS2 samples synthesized via chemical vapor deposition.\nUnder resonant excitation, Pcirc ranges from 2% to 32%, and we observe a\npronounced inverse relationship between photoluminescence (PL) intensity and\nPcirc. High quality samples exhibiting strong PL and long exciton relaxation\ntime exhibit a low degree of valley polarization, and vice versa. This behavior\nis also demonstrated in monolayer WSe2 samples and transferred WS2, indicating\nthat this correlation may be more generally observed and account for the wide\nvariations reported for Pcirc. Time resolved PL provides insight into the role\nof radiative and non-radiative contributions to the observed polarization.\nShort non-radiative lifetimes result in a higher measured polarization by\nlimiting opportunity for depolarizing scattering events.",
        "positive": "Vectorial probing of electric and magnetic transitions in variable\n  optical environments and vice-versa: We use europium doped single crystalline NaYF$_4$ nanorods for probing the\nelectric and magnetic contributions to the local density of optical states\n(LDOS). Reciprocically, we determine intrinsic properties of the emitters\n(oscillator strength, quantum yield) by comparing their measured and simulated\noptical responses in front of a mirror. We first experimentally determine the\nspecifications of the nanoprobe (orientation and oscillator strength of the\nelectric and magnetic dipoles moments) and show significant orientation\nsensitivity of the branching ratios associated with electric and magnetic\ntransitions. In a second part, we measure the modification of the LDOS in front\nof a gold mirror in a Drexhage's experiment. We discuss the role of the\nelectric and magnetic LDOS on the basis of numerical simulations, taking into\naccount the orientation of the dipolar emitters. We demonstrate that they\nbehave like degenerated dipoles sensitive to polarized partial LDOS."
    },
    {
        "anchor": "Gapless surface states in a three-dimensional Chalker-Coddington type\n  network model: We present the emergence of gapless surface states in a three-dimensional\nChalker-Coddington type network model with spatial periodicity. The model\nconsists of a ring network placed on every face of the cubic unit cells in the\nsimple cubic lattice. The scattering among ring-propagating modes in the\nadjacent rings is described by the S-matrices, which control possible\nsymmetries of the system. The model maps to a Floquet-Bloch system, and the\nquasienergy spectrum can exhibit a gapped bulk band structure and gapless\nsurface states. Symmetry properties of the system and robustness of the gapless\nsurface states are explored in comparison to topological crystalline insulator.\nWe also discuss other crystal structures, a gauge symmetry, and a possible\noptical realization of the network model.",
        "positive": "Landau levels of single layer and bilayer phosphorene: In this work we introduce a low-energy Hamiltonian for single layer and\nbilayer black phosphorus that describes the electronic states at the vicinity\nof the gamma point. The model is based on a recently proposed tight-binding\ndescription for electron and hole bands close to the Fermi level. We calculate\nexpressions for the Landau level spectrum as function of magnetic field and in\nthe case of bilayer black phosphorus we investigate the effect of an external\nbias on the electronic band gap. The results showcase the highly anisotropic\ncharacter of black phosphorus and in particular for bilayer BP, the presence of\nbias allows for a field-induced semiconductor-metal transition."
    },
    {
        "anchor": "Anatomy of spin wave driven magnetic texture motion via magnonic torques: The interplay between spin wave and magnetic texture represents the\ninformation exchange between the fast and slow dynamical parts of magnetic\nsystems. Here we formulate a set of magnonic torques acting on background\nmagnetic texture, by extracting time-invariant information from the fast\nprecessing spin waves. Under the frame of magnonic torques, we use theoretical\nformulations and micromagnetic simulations to investigate the spin wave driven\ndomain wall motion in two typical symmetry-breaking situations: the rotational\nsymmetry broken by the Dzyaloshinkii-Moriya interaction, and the translational\nsymmetry broken by magnetic damping. The torque-based microscopic analyses\nprovide compact yet quantitative tools to reinterpret the magnetic texture\ndynamics induced by spin wave, beyond the conventional framework of global\nmomentum conservation.",
        "positive": "Towards a semiclassical justification of the `effective random matrix\n  theory' for transport through ballistic chaotic quantum dots: The scattering matrix S of a ballistic chaotic cavity is the direct sum of a\n`classical' and a `quantum' part, which describe the scattering of channels\nwith typical dwell time smaller and larger than the Ehrenfest time,\nrespectively. According to the `effective random matrix theory' of Silvestrov,\nGoorden, and Beenakker [Phys. Rev. Lett. 90, 116801 (2003)], statistical\naverages involving the quantum-mechanical scattering matrix are given by random\nmatrix theory. While this effective random matrix theory is known not to be\napplicable for quantum interference corrections to transport, which appear to\nsubleading order in the number of scattering channels N, it is believed to\ncorrectly describe quantum transport to leading order in N. We here partially\nverify this belief, by comparing the predictions of the effective random matrix\ntheory for the ensemble averages of polynomial functions of S and S^dagger of\ndegree 2, 4, and 6 to a semiclassical calculation."
    },
    {
        "anchor": "Thermodynamic properties of the electron gas in multilayer graphene in\n  the presence of a perpendicular magnetic field: The thermodynamic properties of the electron gas in multilayer graphene\ndepend strongly on the number of layers and the type of stacking. Here we\nanalyse how those properties change when we vary the number of layers for\nrhombohedral stacked multilayer graphene and compare our results with those\nfrom a conventional two dimensional electron gas. We show that the highly\ndegenerate zero energy Landau level which is partly filled with electrons and\npartly with holes has a strong influence on the value of the different\nthermodynamic quantities.",
        "positive": "Direct Observation of Propagating Gigahertz Coherent Guided Acoustic\n  Phonons in Free Standing Single Copper Nanowires: We report on gigahertz acoustic phonon waveguiding in free-standing single\ncopper nanowires studied by femtosecond transient reflectivity measurements.\nThe results are discussed on the basis of the semianalytical resolution of the\nPochhammer and Chree equation. The spreading of the generated Gaussian wave\npacket of two different modes is derived analytically and compared with the\nobserved oscillations of the sample reflectivity. These experiments provide a\nunique way to independently obtain geometrical and material characterization.\nThis direct observation of coherent guided acoustic phonons in a single\nnano-object is also the first step toward nanolateral size acoustic transducer\nand comprehensive studies of the thermal properties of nanowires."
    },
    {
        "anchor": "Anatomy of Spin and Current Generation from Magnetization Gradients in\n  Topological Insulators and Rashba Metals: We explore the spin density and charge currents arising on the surface of a\ntopological insulator and in a 2D Rashba metal due to magnetization gradients.\nFor topological insulators a single interconversion coefficient controls the\ngeneration of both quantities. This coefficient is quantized to a value\nproportional to the vorticity of the Dirac point which constitutes a hallmark\nof parity anomaly at finite density. As such, it also unveils a robust route to\ndisentangle and detect the protected states of a topological insulator on a\ngiven surface. In stark contrast, Rashba metals do not exhibit such anomalies\nsince they contain an even number of helical branches. Nonetheless, also these\nare governed by quantized responses which, however, are not protected against\nweak disorder. Furthermore, we find that for Rashba metals the interconversion\ncoefficients demonstrate discontinuities and a nontrivial interplay upon\nvarying the chemical potential, the strength of the spin-orbit coupling, and a\npairing gap. Our results have implications for the binding between magnetic\nskyrmions and superconducting vortices, the emergence of Majorana zero modes,\nand pave the way for superconducting diode effects mediated by out-of-plane\nmagnetization gradients.",
        "positive": "Monte Carlo study of a two-dimensional quantum ferromagnet: We present quantum Monte Carlo results for the field and temperature\ndependence of the magnetization and the spin-lattice relaxation rate $1/T_1$ of\na two-dimensional $S=1/2$ quantum Heisenberg ferromagnet. The Monte Carlo\nmethod, which yields results free of systematic errors, is described in detail.\nThe high accuracy of the calculated magnetization allows for stringent tests of\nrecent approximate analytical calculations. We also compare our results with\nrecent experimental data for a $\\nu=1$ quantum Hall ferromagnet, which is\nexpected to be well described by the Heisenberg model. The dynamic response\nfunction needed to extract $1/T_1$ is obtained using maximum-entropy analytic\ncontinuation of the corresponding imaginary-time dependent correlation\nfunction. We discuss the reliability of this approach."
    },
    {
        "anchor": "Coupling of skyrmions mediated by RKKY interaction: A discussion on the interaction between skyrmions in a bi-layer system\nconnected by a non-magnetic metal is presented. From considering a free charge\ncarrier model, we have shown that the Ruderman-Kittel-Kasuya-Yosida (RKKY )\ninter- action can induce attractive or repulsive interaction between the\nskyrmions depending on the spacer thickness. We have also shown that due to an\nincreasing in RKKY energy when the skyrmions are far from each other, their\nwidths are diminished. Finally, we have obtained analytical solutions to the\nskyrmion position when the in-plane distance between the skyrmions is small and\nit is shown that an attractive RKKY interaction yields a skyrmion precessory\nmotion. This RKKY-induced coupling could be used as a skyrmion drag mechanism\nto displace skyrmions in multilayers.",
        "positive": "Exactly solvable model for drift of suspended ferromagnetic particles\n  induced by the Magnus force: The phenomenon of drift motion of single-domain ferromagnetic particles\ninduced by the Magnus force in a viscous fluid is studied analytically. We use\na minimal set of equations to describe the translational and rotational motions\nof these particles subjected to a harmonic force and a non-uniformly rotating\nmagnetic field. Assuming that the azimuthal angle of the magnetic field is a\nperiodic triangular function, we analytically solve the rotational equation of\nmotion in the steady state and calculate the drift velocity of particles. We\nstudy in detail the dependence of this velocity on the model parameters,\ndiscuss the applicability of the drift phenomenon for separation of particles\nin suspensions, and verify numerically the analytical predictions."
    },
    {
        "anchor": "Resistive switching in nanogap systems on SiO2 substrates: Voltage-controlled resistive switching is demonstrated in various gap systems\non SiO2 substrate. The nanosized gaps are made by different means using\ndifferent materials including metal, semiconductor, and metallic nonmetal. The\nswitching site is further reduced by using multi-walled carbon nanotubes and\nsingle-walled carbon nanotubes. The switching in all the gap systems shares the\nsame characteristics. This independence of switching on the material\ncompositions of the electrodes, accompanied by observable damage to the SiO2\nsubstrate at the gap region, bespeaks the intrinsic switching from\npost-breakdown SiO2. It calls for caution when studying resistive switching in\nnanosystems on oxide substrates, since oxide breakdown extrinsic to the\nnanosystem can mimic resistive switching. Meanwhile, the high ON/OFF ratio\n(10E5), fast switching time (2 us, test limit), durable cycles demonstrated\nshow promising memory properties. The intermediate states observed reveal the\nfilamentary conduction nature.",
        "positive": "Hysteresis effect due to the exchange Coulomb interaction in\n  short-period superlattices in tilted magnetic fields: We calculate the ground-state of a two-dimensional electron gas in a\nshort-period lateral potential in magnetic field, with the Coulomb\nelectron-electron interaction included in the Hartree-Fock approximation. For a\nsufficiently short period the dominant Coulomb effects are determined by the\nexchange interaction. We find numerical solutions of the self-consistent\nequations that have hysteresis properties when the magnetic field is tilted and\nincreased, such that the perpendicular component is always constant. This\nbehavior is a result of the interplay of the exchange interaction with the\nenergy dispersion and the spin splitting. We suggest that hysteresis effects of\nthis type could be observable in magneto-transport and magnetization\nexperiments on quantum-wire and quantum-dot superlattices."
    },
    {
        "anchor": "A Compact Approximate Solution to the Kondo Problem: A compact approximate groundstate of the Kondo problem is introduced. It\nconsists of four Slater states. The spin up and down states of the localized\nd-impurity are paired with two localized s-electron states of opposite spin.\nAll the remaining s-electron states are rearranged forming two new optimal\northonormal bases. Through a rotation in Hilbert space the two localized states\n(and the rest of the bases) are optimized by minimizing the energy expectation\nvalue. The ground-state energy E and the singlet-triplet excitation energy dE\nare calculated numerically. Although the two energies can differ by a factor of\n1000, they are obtained simultaneously. The singlet-triplet excitation energy\ndE is proportional to exp[-1/2Jg] and quite close to the Kondo temperature\nk_BT_K. The cases for anti-ferromagnetic (J>0) and ferromagnetic (J<0) coupling\nare investigated.",
        "positive": "Single-molecule study for a graphene-based nano-position sensor: In this study we lay the groundwork for a graphene-based fundamental ruler at\nthe nanoscale. It relies on the efficient energy-transfer mechanism between\nsingle quantum emitters and low-doped graphene monolayers. Our experiments,\nconducted with dibenzoterrylene (DBT) molecules, allow going beyond ensemble\nanalysis due to the emitter photo-stability and brightness. A quantitative\ncharacterization of the fluorescence decay-rate modification is presented and\ncompared to a simple model, showing agreement with the $d^{-4}$ dependence, a\ngenuine manifestation of a dipole interacting with a 2D material. With DBT\nmolecules, we can estimate a potential uncertainty in position measurements as\nlow as 5nm in the range below 30nm."
    },
    {
        "anchor": "Electrically and mechanically tunable electron spins in silicon carbide\n  color centers: The electron spins of semiconductor defects can have complex interactions\nwith their host, particularly in polar materials like SiC where electrical and\nmechanical variables are intertwined. By combining pulsed spin resonance with\nab-initio simulations, we show that spin-spin interactions within SiC neutral\ndivacancies give rise to spin states with an enhanced Stark effect, sub-10**-6\nstrain sensitivity, and highly spin-dependent photoluminescence with intensity\ncontrasts of 15-36%. These results establish SiC color centers as compelling\nsystems for sensing nanoscale fields.",
        "positive": "Ultrasonic attenuation via energy diffusion channel in disordered\n  conductors: We predict an existence of an new dissipation channel leading to attenuation\nof ultrasound in disordered conductors and superconductors with perfect\nelectroneutrality. It is due to slow diffusion of thermal energy. We show that\nin doped silicon ultrasound attenuation may be enhanced by a factor about 100.\nSimilar effect is also studied for s-wave and d-wave superconductors. The\nlatter case is applied to BSCCO family where strong enhancement of ultrasound\nattenuation is predicted. For usual s-wave superconductors new dissipation\nchannel might be important for very low-electron-density materials near the\nBCS-BEC crossover."
    },
    {
        "anchor": "Tailoring Light-Matter Interaction with a Nanoscale Plasmon Resonator: We propose and demonstrate a new approach for achieving strong light-matter\ninteractions with quantum emitters. Our approach makes use of a plasmon\nresonator composed of defect-free, highly crystalline silver nanowires\nsurrounded by patterned dielectric distributed Bragg reflectors (DBRs). These\nresonators have an effective mode volume (Veff) two orders of magnitude below\nthe diffraction limit and quality factor (Q) approaching 100, enabling\nenhancement of spontaneous emission rates by a factor exceeding 75 at the\ncavity resonance. We also show that these resonators can be used to convert a\nbroadband quantum emitter to a narrowband single-photon source with\ncolor-selective emission enhancement.",
        "positive": "Semiclassical trace formulae using coherent states: We derive semiclassical trace formulae including Gutzwiller's trace formula\nusing coherent states. This formulation has several advantages over the usual\ncoordinate-space formulation. Using a coherent-state basis makes it immediately\nobvious that classical periodic orbits make separate contributions to the trace\nof the quantum-mechanical time evolution operator. In addition, our approach is\nmanifestly canonically invariant at all stages, and leads to the simplest\npossible derivation of Gutzwiller's formula."
    },
    {
        "anchor": "Artificial quantum-dot Helium molecules: Electronic spectra, spin\n  structures, and Heisenberg clusters: Energy spectra and spin configurations of a system of N=4 electrons in\nlateral double quantum dots (quantum dot Helium molecules) are investigated\nusing exact diagonalization (EXD), as a function of interdot separation,\napplied magnetic field (B), and strength of interelectron repulsion. As a\nfunction of the magnetic field, the energy spectra exhibit a low-energy band\nconsisting of a group of six states, with the number six being a consequence of\nthe conservation of the total spin and the ensuing spin degeneracies for four\nelectrons. The energies of the six states appear to cross at a single value of\nthe magnetic field, and with increasing Coulomb repulsion they tend to become\ndegenerate, with a well defined energy gap separating them from the\nhigher-in-energy excited states. The appearance of the low-energy band is a\nconsequence of the formation of a Wigner supermolecule, with the four electrons\n(two in each dot) being localized at the vertices of a rectangle. Using\nspin-resolved pair-correlation distributions, a method for mapping the\ncomplicated EXD many-body wave functions onto simpler spin functions associated\nwith a system of four localized spins is introduced. Detailed interpretation of\nthe EXD spin functions and EXD spectra associated with the low-energy band via\na 4-site Heisenberg cluster (with B-dependent exchange integrals) is\ndemonstrated. Aspects of spin entanglement, referring to the well known N-qubit\nDicke states, are also discussed.",
        "positive": "Non-equilibrium frequency-dependent noise through a quantum dot: A real\n  time functional renormalization group approach: We construct a real time current-conserving functional renormalization group\n(RG) scheme on the Keldysh contour to study frequency-dependent transport and\nnoise through a quantum dot in the local moment regime. We find that the\ncurrent vertex develops a non-trivial non-local structure in time, governed by\na new set of RG equations. Solving these RG equations, we compute the complete\nfrequency and temperature-dependence of the noise spectrum. For voltages large\ncompared to the Kondo temperature, $eV \\gg k_BT_K$, two sharp anti-resonances\nare found in the noise spectrum at frequencies $\\hbar \\omega = \\pm e V$, and\ncorrespondingly, two peaks in the ac conductance through the dot."
    },
    {
        "anchor": "Electrical spin manipulation in graphene nanostructures: We propose a mechanism to drive singlet-triplet spin transitions\nelectrically, in a wide class of graphene nanostructures that present pairs of\nin-gap zero modes, localized at opposite sublattices. Examples are rectangular\nnanographenes with short zigzag edges, armchair ribbon heterojunctions with\ntopological in-gap states and graphene islands with sp$^3$ functionalization.\nThe interplay between the hybridization of zero modes and Coulomb repulsion\nleads to symmetric exchange interaction that favors a singlet ground state.\nApplication of an off-plane electric field to the graphene nanostructure\ngenerates an additional Rashba spin-orbit coupling, which results in\nantisymmetric exchange interaction that mixes $S=0$ and $S=1$ manifolds. We\nshow that modulation in time of either the off-plane electric field or the\napplied magnetic field permits to perform electrically driven spin resonance in\na system with very long spin relaxation times.",
        "positive": "Conductivity scaling and the effects of symmetry-breaking terms in\n  bilayer graphene Hamiltonian: We study the ballistic conductivity of bilayer graphene in the presence of\nsymmetry-breaking terms in effective Hamiltonian for low-energy excitations,\nsuch as the trigonal-warping term ($\\gamma_3$), the electron-hole symmetry\nbreaking interlayer hopping ($\\gamma_4$), and the staggered potential\n($\\delta_{AB}$). Earlier, it was shown that for $\\gamma_3\\neq{}0$, in the\nabsence of remaining symmetry-breaking terms (i.e., $\\gamma_4=\\delta_{AB}=0$),\nthe conductivity ($\\sigma$) approaches the value of $3\\sigma_0$ for the system\nsize $L\\rightarrow{}\\infty$ (with $\\sigma_0=8e^2/(\\pi{}h)$ being the result in\nthe absence of trigonal warping, $\\gamma_3=0$). We demonstrate that\n$\\gamma_4\\neq{}0$ leads to the divergent conductivity if $\\gamma_3\\neq{}0$, or\nto the vanishing conductivity if $\\gamma_3=0$. For realistic values of the\ntight-binding model parameters, $\\gamma_3=0.3\\,$eV, $\\gamma_4=0.15\\,$eV (and\n$\\delta_{AB}=0$), the conductivity values are in the range of\n$\\sigma/\\sigma_0\\approx{}4-5$ for $100\\,$nm$\\ <L<1\\,\\mu$m, in agreement with\nexisting experimental results. The staggered potential ($\\delta_{AB}\\neq{}0$)\nsuppresses zero-temperature transport, leading to $\\sigma\\rightarrow{}0$ for\n$L\\rightarrow{}\\infty$. Although $\\sigma=\\sigma(L)$ is no longer universal, the\nFano factor approaches the pseudodiffusive value ($F\\rightarrow{}1/3$ for\n$L\\rightarrow{}\\infty$) in any case with non-vanishing $\\sigma$ (otherwise,\n$F\\rightarrow{}1$) signaling the transport is ruled by evanescent waves.\nTemperature effects are briefly discussed in terms of a phenomenological model\nfor staggered potential $\\delta_{AB}=\\delta_{AB}(T)$ showing that, for\n$0<T\\leqslant{}T_c\\approx{}12\\,$K and $\\delta_{AB}(0)=1.5\\,$meV, $\\sigma(L)$ is\nnoticeably affected by $T$ for $L\\gtrsim{}100\\,$nm."
    },
    {
        "anchor": "Reflectionless Klein tunneling of Dirac fermions: Comparison of\n  split-operator and staggered-lattice discretization of the Dirac equation: Massless Dirac fermions in an electric field propagate along the field lines\nwithout backscattering, due to the combination of spin-momentum locking and\nspin conservation. This phenomenon, known as \"Klein tunneling\", may be lost if\nthe Dirac equation is discretized in space and time, because of scattering\nbetween multiple Dirac cones in the Brillouin zone. To avoid this, a staggered\nspace-time lattice discretization has been developed in the literature, with\none single Dirac cone in the Brillouin zone of the original square lattice.\nHere we show that the staggering doubles the size of the Brillouin zone, which\nactually contains two Dirac cones. We find that this fermion doubling causes a\nspurious breakdown of Klein tunneling, which can be avoided by an alternative\nsingle-cone discretization scheme based on a split-operator approach.",
        "positive": "Quantum charge diffusion in underdamped Josephson junctions and\n  superconducting nanowires: The effect of quantum fluctuations on the current-voltage characteristics of\nJosephson junctions and superconducting nanowires is studied in the underdamped\nlimit. Quantum fluctuations induce transitions between a Coulomb--blockade and\na supercurrent branch, and can significantly modify the shape of\ncurrent-voltage characteristics in the case of a highly resistive environment.\nOwing to the phase-charge duality, our results can be directly extended to the\nopposite overdamped limit."
    },
    {
        "anchor": "Transient dynamics of a molecular quantum dot with a vibrational degree\n  of freedom: We investigate the transient effects occurring in a molecular quantum dot\ndescribed by an Anderson-Holstein Hamiltonian which is instantly coupled to two\nfermionic leads biased by a finite voltage. In the limit of weak\nelectron-phonon interaction, we use perturbation theory to determine the\ntime-dependence of the dot population and the average current. The limit of\nstrong coupling is accessed by means of a self-consistent time-dependent\nmean-field approximation. These comple- mentary approaches allow us to\ninvestigate the dynamics of the inelastic effects occurring when the applied\nbias voltage exceeds the phonon frequency and the emergence of bistability.",
        "positive": "Tripartite Phonon-Magnon-Plasmon Coupling, Parametric Amplification, and\n  Formation of a Phonon-Magnon-Plasmon Polariton in a Two-Dimensional Periodic\n  Array of Magnetostrictive/Plasmonic Bilayered Nanodots: Coupling between spin waves (SWs) and other types of waves in nanostructured\nmagnetic media has garnered increased attention in recent years because of the\nrich physics and the potential to produce disruptive technologies. Among this\nfamily of intriguing phenomena, we recently reported a new one: coupling\nbetween SWs and hybridized phonon-plasmon waves, resulting in tripartite\ncoupling of magnons, phonons, and plasmons. Here, this acousto-plasmo-magnonic\nphenomenon is studied in a two-dimensional periodic array of bilayered [Co/Al]\nnanodots on a silicon substrate, where the Co is a magnetostrictive constituent\nresponsive to magneto-elastic coupling and the Al acts as a source of surface\nplasmons. Time-resolved magneto-optical-Kerr-effect microscopy revealed\nparametric amplification and strong coupling between two spin wave modes\nmediated by a hybrid phonon-plasmon wave. The strong coupling forms a new\nquasi-particle: the phonon-plasmonmagnon polariton."
    },
    {
        "anchor": "Simulating dynamically assisted production of Dirac pairs in gapped\n  graphene monolayers: In a vicinity of the Fermi surface, graphene layers with bandgaps allow for\nclosely simulating the vacuum of quantum electrodynamics and, thus, its yet\nunverified strong-field phenomenology with accessible field strengths. This\nstriking feature is exploited to investigate a plausible materialization of\ndynamically assisted pair production through the analog production of light but\nmassive pairs of Dirac quasiparticles. The process is considered in a field\nconfiguration combining a weak high-frequency electric mode and a strong\nlow-frequency electric field oscillating in time. Its theoretical study is\ncarried out from a quantum kinetic approach, similar to the one governing the\nspontaneous production of pairs in QED. We show that the presence of the weak\nassisting mode can strongly increase the number of produced massive Dirac pairs\nas compared with a setup driven by the strong field only. The efficiency of the\nprocess is contrasted, moreover, with the case of gapless graphene to highlight\nthe role played by the quasiparticle mass.",
        "positive": "Capacitive Spring Softening in Single-Walled Carbon Nanotube\n  Nanoelectromechanical Resonators: We report the capacitive spring softening effect observed in single-walled\ncarbon nanotube (SWNT) nanoelectromechanical (NEM) resonators. The nanotube\nresonators adopt dual-gate configuration with both bottom-gate and side-gate\ncapable of tuning the resonance frequency through capacitive coupling.\nInterestingly, downward resonance frequency shifting is observed with\nincreasing side-gate voltage, which can be attributed to the capacitive\nsoftening of spring constant. Furthermore, in-plane vibrational modes exhibit\nmuch stronger spring softening effect than out-of-plan modes. Our dual-gate\ndesign should enable the differentiation between these two types of vibrational\nmodes, and open up new possibility for nonlinear operation of nanotube\nresonators."
    },
    {
        "anchor": "Fingerprints of Majorana fermions in spin-resolved subgap spectroscopy: When a strongly correlated quantum dot is tunnel-coupled to a superconductor,\nit leads to the formation of Shiba bound states inside the superconducting gap.\nThey have been measured experimentally in a superconductor-quantum dot-normal\nlead setup. Side coupling the quantum dot to a topological superconducting wire\nthat supports Majorana bound states at its ends, drastically affects the\nstructure of the Shiba states and induces supplementary in-gap states. The\nanomalous coupling between the Majorana bound states and the quantum dot gives\nrise to a characteristic imbalance in the spin resolved spectral functions for\nthe dot operators. These are clear fingerprints for the existence of Majorana\nfermions and they can be detected experimentally in transport measurements. In\nterms of methods employed, we have used analytical approaches combined with the\nnumerical renormalization group approach.",
        "positive": "Harper-Hofstadter problem for 2D electron gas with ${\\bf k}$-linear\n  Rashba spin-orbit coupling: The Harper-Hofstadter problem for two-dimensional electron gas with Rashba\nspin-orbit coupling subject to periodic potential and perpendicular magnetic\nfield is studied analytically and numerically. The butterfly-like energy\nspectrum, spinor wave functions as well as the spin density and average spin\npolarization are calculated for actual parameters of semiconductor structure.\nOur calculations show that in two-dimensional electron gas subject to periodic\npotential and uniform magnetic field the effects of energy spectrum splitting\ncaused by large spin-orbit Rashba coupling can be observed experimentally."
    },
    {
        "anchor": "Effects of different 3D QED vertex ansaetze on critical coupling: We study the semi-metal/insulator phase transition in graphene using a\nSchwinger-Dyson approach. We consider various forms of vertex ansaetze to\ntruncate the hierarchy of Schwinger-Dyson equations. We define a Ball-Chiu type\nvertex that truncates the equations without violating gauge invariance. We show\nthat there is a family of these vertices, parametrized by a continuous\nparameter that we call a, all of which satisfy the Ward identity. We have\ncalculated the critical coupling of the phase transition using different values\nof a. We have also tested a common approximation in which only the first term\nin the Ball-Chiu ansatz is included. This vertex is independent of a, and,\nalthough it is not gauge invariant, it has been used many times in the\nliterature because of the numerical simplifications it provides. We have found\nthat, with a one-loop photon polarization tensor, the results obtained for the\ncritical coupling from the truncated vertex and the full vertex with a = 1\nagree very well, but other values of a give significantly different results. We\nhave also done a fully self-consistent calculation, in which the photons are\nbackcoupled to the fermion degrees of freedom, for one choice a = 1. Our\nresults show that when photon dynamics are correctly taken into account, it is\nno longer true that the truncated vertex and the full Ball-Chiu vertex with a =\n1 agree well. The conclusion is that traditional vertex truncations do not\nreally make sense in a system that does not respect Lorentz invariance, like\ngraphene, and the need to include vertex contributions self-consistently is\nlikely inescapable.",
        "positive": "Band mass anisotropy and the intrinsic metric of fractional quantum Hall\n  systems: It was recently pointed out that topological liquid phases arising in the\nfractional quantum Hall effect (FQHE) are not required to be rotationally\ninvariant, as most variational wavefunctions proposed to date have been.\nInstead, they possess a geometric degree of freedom corresponding to a shear\ndeformation that acts like an intrinsic metric. We apply this idea to a system\nwith an anisotropic band mass, as is intrinsically the case in many-valley\nsemiconductors such as AlAs and Si, or in isotropic systems like GaAs in the\npresence of a tilted magnetic field, which breaks the rotational invariance. We\nperform exact diagonalization calculations with periodic boundary conditions\n(torus geometry) for various filling fractions in the lowest, first and second\nLandau levels. In the lowest Landau level, we demonstrate that FQHE states\ngenerally survive the breakdown of rotational invariance by moderate values of\nthe band mass anisotropy. At 1/3 filling, we generate a variational family of\nLaughlin wavefunctions parametrized by the metric degree of freedom. We show\nthat the intrinsic metric of the Laughlin state adjusts as the band mass\nanisotropy or the dielectric tensor are varied, while the phase remains robust.\nIn the n=1 Landau level, mass anisotropy drives transitions between\nincompressible liquids and compressible states with charge density wave\nordering. In n>=2 Landau levels, mass anisotropy selects and enhances stripe\nordering with compatible wave vectors at partial 1/3 and 1/2 fillings."
    },
    {
        "anchor": "Enhanced Thermal Transport across the Interface between Charged Graphene\n  Electrodes and Poly(ethylene oxide) Electrolytes by Non-covalent\n  Functionalization: Interfacial thermal transport between electrodes and polymer electrolytes can\nplay a crucial role in the thermal management of solid-state lithium-ion\nbatteries (SLIBs). Modifying the electrode surface with functional molecules\ncan effectively increase the interfacial thermal conductance (ITC) between\nelectrodes and polymers (e.g., electrolytes, separators); however, how they\ninfluence the interfacial thermal transport in SLIBs during charge/discharge\nremains unknown. In this work, we conduct molecular dynamics (MD) simulations\nto investigate the ITC between charged electrodes and solid-state polymer\nelectrolytes (SPEs) mixed with ionic liquids (ILs). We find that ILs could self\nassemble at the electrode surface and act as non-covalent functional molecules\nthat could significantly enhance the interfacial thermal transport during\ncharge/discharge because of the formation of a densely packed cationic or\nanionic layer at the interface. While the electrostatic interactions between\nthe charged electrode and the IL ions are responsible for forming these dense\ninterfacial layers, the enhancement of ITC is mainly contributed by the\nincreased Lennard-Jones (LJ) interactions between the charged electrodes and\nILs. This work may provide useful insights into the understanding of\ninterfacial thermal transport between electrodes and electrolytes of SLIBs\nduring charge/discharge.",
        "positive": "Temperature performance analysis of terahertz quantum cascade lasers:\n  Vertical versus diagonal designs: Resonant phonon depopulation terahertz quantum cascade lasers based on\nvertical and diagonal lasing transitions are systematically compared using a\nwell established ensemble Monte Carlo approach. The analysis shows that for\noperating temperatures below 200 K, diagonal designs may offer superior\ntemperature performance at lasing frequencies of about 3.5 THz and above;\nhowever, vertical structures are more advantageous for good temperature\nperformance at lower frequencies."
    },
    {
        "anchor": "Dynamic response of trapped ultracold bosons on optical lattices: We study the dynamic response of ultracold bosons trapped in one-dimensional\noptical lattices using Quantum Monte Carlo simulations of the boson Hubbard\nmodel with a confining potential. The dynamic structure factor reveals the\ninhomogeneous nature of the low temperature state, which contains coexisting\nMott insulator and superfluid regions. We present new evidence for local\nquantum criticality and shed new light on the experimental excitation spectrum\nof 87Rb atoms confined in one dimension.",
        "positive": "Shifting a Quantum Wire through a Disordered Crystal: Observation of\n  Conductance Fluctuations in Real Space: A quantum wire is spatially displaced by suitable electric fields with\nrespect to the scatterers inside a semiconductor crystal. As a function of the\nwire position, the low-temperature resistance shows reproducible fluctuations.\nTheir characteristic temperature scale is a few hundred millikelvin, indicating\na phase-coherent effect. Each fluctuation corresponds to a single scatterer\nentering or leaving the wire. This way, scattering centers can be counted one\nby one."
    },
    {
        "anchor": "Gauge Theory of Composite Fermions: Particle-Flux Separation in Quantum\n  Hall Systems: Fractionalization phenomenon of electrons in quantum Hall states is studied\nin terms of U(1) gauge theory. We focus on the Chern-Simons(CS) fermion\ndescription of the quantum Hall effect(QHE) at the filling factor\n$\\nu=p/(2pq\\pm 1)$, and show that the successful composite-fermions(CF) theory\nof Jain acquires a solid theoretical basis, which we call particle-flux\nseparation(PFS). PFS can be studied efficiently by a gauge theory and\ncharacterized as a deconfinement phenomenon in the corresponding gauge\ndynamics. The PFS takes place at low temperatures, $T \\leq T_{\\rm PFS}$, where\neach electron or CS fermion splinters off into two quasiparticles, a fermionic\nchargeon and a bosonic fluxon. The chargeon is nothing but Jain's CF, and the\nfluxon carries $2q$ units of CS fluxes. At sufficiently low temperatures $T\n\\leq T_{\\rm BC} (< T_{\\rm PFS})$, fluxons Bose-condense uniformly and (partly)\ncancel the external magnetic field, producing the correlation holes. This\npartial cancellation validates the mean-field theory in Jain's CF approach.\nFQHE takes place at $T < T_{\\rm BC}$ as a joint effect of (i) integer QHE of\nchargeons under the residual field $\\Delta B$ and (ii) Bose condensation of\nfluxons. We calculate the phase-transition temperature $T_{\\rm PFS}$ and the CF\nmass. PFS is a counterpart of the charge-spin separation in the t-J model of\nhigh-$T_{\\rm c}$ cuprates in which each electron dissociates into holon and\nspinon. Quasiexcitations and resistivity in the PFS state are also studied. The\nresistivity is just the sum of contributions of chargeons and fluxons, and\n$\\rho_{xx}$ changes its behavior at $T = T_{\\rm PFS}$, reflecting the change of\nquasiparticles from chargeons and fluxons at $T < T_{\\rm PFS}$ to electrons at\n$T_{\\rm PFS} < T$.",
        "positive": "Observation of topologically protected bound states in a one dimensional\n  photonic system: One of the most striking features of quantum mechanics is the appearance of\nphases of matter with topological origins. These phases result in remarkably\nrobust macroscopic phenomena such as the edge modes in integer quantum Hall\nsystems, the gapless surface states of topological insulators, and elementary\nexcitations with non-abelian statistics in fractional quantum Hall systems and\ntopological superconductors. Many of these states hold promise in the\napplications to quantum memories and quantum computation. Artificial quantum\nsystems, with their precise controllability, provide a versatile platform for\ncreating and probing a wide variety of topological phases. Here we investigate\ntopological phenomena in one dimension, using photonic quantum walks. The\nphoton evolution simulates the dynamics of topological phases which have been\npredicted to arise in, for example, polyacetylene. We experimentally confirm\nthe long-standing prediction of topologically protected localized states\nassociated with these phases by directly imaging their wavefunctions. Moreover,\nwe reveal an entirely new topological phenomenon: the existence of a\ntopologically protected pair of bound states which is unique to periodically\ndriven systems. Our experiment demonstrates a powerful new approach for\ncontrolling topological properties of quantum systems through periodic driving."
    },
    {
        "anchor": "A generalized Caroli formula for transmission coefficient with lead-lead\n  coupling: We present a generalized transmission coefficient formula for the\nlead-junction-lead system, in which interaction between the leads has been\ntaken into account. Based on it the Caroli formula could be easily recovered\nand a transmission coefficient formula for interface problem in the ballistic\nsystem can be obtained. The condition of validity for the formula is carefully\nexplored. We mainly focus on heat transport. However, the corresponding\nelectrical transport could be similarly dealt with. Also, an illustrative\nexample is given to clarify the precise meaning of the quantities used in the\nformula, such as the concept of the reduced interacting matrix in different\nsituations. In addition, an explicit transmission coefficient formula for a\ngeneral one-dimensional interface setup is obtained based on the derived\ninterface formula.",
        "positive": "Comparison of Spin-Wave Modes in Connected and Disconnected Artificial\n  Spin Ice Nanostructures Using Brillouin Light Scattering Spectroscopy: Artificial spin ice systems have seen burgeoning interest due to their\nintriguing physics and potential applications in reprogrammable memory, logic\nand magnonics. Integration of artificial spin ice with functional magnonics is\na relatively recent research direction, with a host of promising results. As\nthe field progresses, direct in-depth comparisons of distinct artificial spin\nsystems are crucial to advancing the field. While studies have investigated the\neffects of different lattice geometries, little comparison exists between\nsystems comprising continuously connected nanostructures, where spin-waves\npropagate via dipole-exchange interaction, and systems with nanobars\ndisconnected at vertices where spin-wave propagation occurs via stray\ndipolar-field. Gaining understanding of how these very different coupling\nmethods affect both spin-wave dynamics and magnetic reversal is key for the\nfield to progress and provides crucial system-design information including for\nfuture systems containing combinations of connected and disconnected elements.\nHere, we study the magnonic response of two kagome spin ices via Brillouin\nlight scattering, a continuously connected system and a disconnected system\nwith vertex gaps. We observe distinct high-frequency dynamics and magnetization\nreversal regimes between the systems, with key distinctions in spin-wave\nlocalization and mode quantization, microstate-trajectory during reversal and\ninternal field-profiles. These observations are pertinent for the fundamental\nunderstanding of artificial spin systems and broader design and engineering of\nreconfigurable functional magnonic crystals."
    },
    {
        "anchor": "Aharonov-Bohm cages in the GaAlAs/GaAs system: Aharonov-Bohm oscillations have been observed in a lattice formed by a two\ndimensional rhombus tiling. This observation is in good agreement with a recent\ntheoretical calculation of the energy spectrum of this so-called T3 lattice. We\nhave investigated the low temperature magnetotransport of the T3 lattice\nrealized in the GaAlAs/GaAs system. Using an additional electrostatic gate, we\nhave studied the influence of the channel number on the oscillations amplitude.\nFinally, the role of the disorder on the strength of the localization is\ntheoretically discussed.",
        "positive": "Anomalous metallic phase in molybdenum disulphide induced via\n  gate-driven organic ion intercalation: Transition metal dichalcogenides exhibit rich phase diagrams dominated by the\ninterplay of superconductivity and charge density waves, which often result in\nanomalies in the electric transport properties. Here, we employ the ionic\ngating technique to realize a tunable, non-volatile organic ion intercalation\nin bulk single crystals of molybdenum disulphide (MoS$_{2}$). We demonstrate\nthat this gate-driven organic ion intercalation induces a strong electron\ndoping in the system without changing the pristine $2H$ crystal symmetry and\ntriggers the emergence of a re-entrant insulator-to-metal transition. We show\nthat the gate-induced metallic state exhibits clear anomalies in the\ntemperature dependence of the resistivity with a natural explanation as\nsignatures of the development of a charge-density wave phase which was\npreviously observed in alkali-intercalated MoS$_{2}$. The relatively large\ntemperature at which the anomalies are observed ($\\sim$$150$ K), combined with\nthe absence of any sign of doping-induced superconductivity down to $\\sim$$3$\nK, suggests that the two phases might be competing with each other to determine\nthe electronic ground state of electron-doped MoS$_2$."
    },
    {
        "anchor": "Raman spectroscopy study of rotated double-layer graphene:\n  Misorientation-angle dependence of electronic structure: We present a systematic Raman study of unconventionally-stacked double-layer\ngraphene, and find that the spectrum strongly depends on the relative rotation\nangle between layers. Rotation-dependent trends in the position, width and\nintensity of graphene 2D and G peaks are experimentally established and\naccounted for theoretically. Our theoretical analysis reveals that changes in\nelectronic band structure due to the interlayer interaction, such as\nrotational-angle dependent Van Hove singularities, are responsible for the\nobserved spectra features. Our combined experimental and theoretical study\nprovides a deeper understanding of the electronic band structure of rotated\ndouble-layer graphene, and leads to a practical way to identify and analyze\nrotation angles of misoriented double-layer graphene.",
        "positive": "Transport in magnetically doped topological insulators: Effects of\n  magnetic clusters: We study the electron transport in a magnetically doped three dimensional\ntopological insulator (TI) by taking the effects of impurity-impurity exchange\ninteractions into account. The interactions between magnetic impurities give\nrise to the formation of {\\it magnetic clusters} with temperature dependent\nmean sizes, randomly distributed on the surface of the TI. Instead of dealing\nwith single magnetic impurities, we consider surface Dirac electrons to be\nscattered off magnetic clusters, and define the scattering potential in terms\nof clusters mean sizes. Within the semiclassical Boltzmann approach, employing\na generalized relaxation time approximation, we obtain the surface conductivity\nof the TI by solving four sets of recursive relations and demonstrate that, the\nsystem is highly anisotropic and the surface conductivities possess\nnon-monotonic behaviors, they strongly depends on the direction, the mean size\nand the number of magnetic clusters. We demonstrate that the dependence of the\nanisotropic magnetoresistance (AMR) to the spin direction of the magnetic\nclusters is inconsistent with the angular dependence of the TI doped with\nnon-interacting magnetic impurities. Our results are consistent with the recent\nexperiment on the AMR of the Cr-doped $\\rm {(Bi, Sb)}_2{\\rm Te}_3$ TI."
    },
    {
        "anchor": "Non-volatile reconfigurable spin logic device: parallel operations: A new proposal is given for designing a non-volatile, completely spin logic\ndevice, that can be reprogrammed for different functional classical logical\noperations. We use the concept of bias driven spin dependent circular current\nand current induced magnetic field in a quantum ring under asymmetric\nring-to-electrode interface configuration to implement all the Boolean\noperations. We extend our idea to build two kinds of parallel computing\narchitectures for getting parallelized operations, all at a particular time.\nFor one case, different kinds of parallel operations are performed in a single\ndevice, whereas in the other type all the possible inputs of a logic gate are\nprocessed in parallel and all the outputs are read simultaneously. The\nperformance and reliability are investigated in terms of power, delay and\npower-delay-product and finally the system temperature. We find that both the\nindividual and simultaneous logic operations studied here are much superior\ncompared to the operations performed in different conventional logic families\nlike complementary metal oxide semiconductor logic, transistor-transistor\nlogic, etc. The key advantage is that we can perform several logic operations,\nas many as we wish, repeating the same or different logic gates using a single\nsetup, which indeed reduces wiring in the circuits and hence consumes much less\npower. Our analysis can be utilized to design optimized logic circuits at\nnano-scale level.",
        "positive": "Tunable few-electron double quantum dots and Klein tunnelling in\n  ultra-clean carbon nanotubes: Quantum dots defined in carbon nanotubes are a platform for both basic\nscientific studies and research into new device applications. In particular,\nthey have unique properties that make them attractive for studying the coherent\nproperties of single electron spins. To perform such experiments it is\nnecessary to confine a single electron in a quantum dot with highly tunable\nbarriers, but disorder has until now prevented tunable nanotube-based\nquantum-dot devices from reaching the single-electron regime. Here, we use\nlocal gate voltages applied to an ultra-clean suspended nanotube to confine a\nsingle electron in both a single quantum dot and, for the first time, in a\ntunable double quantum dot. This tunability is limited by a novel type of\ntunnelling that is analogous to that in the Klein paradox of relativistic\nquantum mechanics."
    },
    {
        "anchor": "Engineering Floquet topological phases using elliptically polarized\n  light: We study a two-dimensional topological system driven out of equilibrium by\nthe application of elliptically polarized light. In particular, we analyze the\nBernevig-Hughes-Zhang model when it is perturbed using an elliptically\npolarized light of frequency $\\Omega$ described in general by a vector\npotential ${\\bf A}(t) = (A_{0x} \\cos(\\Omega t), A_{0y} \\cos(\\Omega t +\n\\phi_0))$. (Linear and circular polarizations can be obtained as special cases\nof this general form by appropriately choosing $A_{0x}$, $A_{0y}$, and\n$\\phi_0$). Even for a fixed value of $\\phi_0$, we can change the topological\ncharacter of the system by changing the ratio of the $x$ and $y$ components of\nthe drive. We therefore find a rich topological phase diagram as a function of\n$A_{0x}$, $A_{0y}$ and $\\phi_0$. In each of these phases, the topological\ninvariant given by the Chern number is consistent with the number of\nspin-polarized states present at the edges of a nanoribbon.",
        "positive": "Spectral Properties of Three Dimensional Layered Quantum Hall Systems: We investigate the spectral statistics of a network model for a three\ndimensional layered quantum Hall system numerically. The scaling of the\nquantity $J_0={1/2}< s^2>$ is used to determine the critical exponent $\\nu$ for\nseveral interlayer coupling strengths. Furthermore, we determine the level\nspacing distribution $P(s)$ as well as the spectral compressibility $\\chi$ at\ncriticality. We show that the tail of $P(s)$ decays as $\\exp(-\\kappa s)$ with\n$\\kappa=1/(2\\chi)$ and also numerically verify the equation\n$\\chi=(d-D_2)/(2d)$, where $D_2$ is the correlation dimension and $d=3$ the\nspatial dimension."
    },
    {
        "anchor": "Lindblad equation for a non-interacting fermionic system: full-counting\n  statistics: We develop a method of calculating the full-counting statistics for a\nnon-interacting fermionic system coupled to the memory-less reservoirs. The\nevolution of the system is described by the Lindblad equation. By the basis\nchange the Liouvillian operator is brought to the quadratic form. This allows\nus a straightforward calculation of any observable in the non-equilibrium\nsteady state. We introduce the counting field in the Lindblad equation which\nbrings us to the generating function and helps us to obtain all cumulants of\nthe charge transport. For the two-site system we give the expression for the\ngenerating function. For system longer than two sites we perform numerical\ninvestigations which suggest that it in a uniform system the cumulants of order\n$k$ are independent of the size of the system for system sizes larger $k+1$.\nThe counting statistics from the Lindblad approach does not take into account\ninterference in the reservoirs which gives a decreased noise in comparison with\nthe Green function method which describes phase coherent leads. The current\nobtained by two methods is the same, which relies on the current conservation.\nThe Fano factors are different (with a linear relation connecting them) and\nallow to distinguish between memory-less and phase coherent reservoirs.",
        "positive": "Giant Planar Hall Effect in the Dirac Semimetal ZrTe5: Recently, giant planar Hall effect originating from chiral anomaly has been\npredicted in nonmagnetic Dirac/Weyl semimetals. ZrTe5 is considered to be an\nintriguing Dirac semimetal at the boundary of weak topological insulators and\nstrong topological insulators, though this claim still remains controversial.\nHere, we report the observation in ZrTe5 of the giant planar Hall resistivity\nthat shows two different magnetic-field dependences as predicted by theory and\na maximum at the Lifshitz transition temperature. We found that the giant\nplanar Hall resistivity fades out with decreasing the thickness of ZrTe5\nnanoplates, which may be ascribed to the vanishing of the 3D nature of the\nsamples. In addition, we have observed a nontrivial Berry phase,\nchiral-anomaly-induced negative longitudinal magnetoresistance, and a giant\nin-plane anisotropic magnetoresistance in these ZrTe5 nanoplates. All the\nexperimental observations demonstrated coherently that ZrTe5 is a Dirac\nsemimetal."
    },
    {
        "anchor": "Transition of laser-induced terahertz spin currents from torque- to\n  conduction-electron-mediated transport: Spin transport is crucial for future spintronic devices operating at\nbandwidths up to the terahertz (THz) range. In F|N thin-film stacks made of a\nferro/ferrimagnetic layer F and a normal-metal layer N, spin transport is\nmediated by (1) spin-polarized conduction electrons and/or (2) torque between\nelectron spins. To identify a cross-over from (1) to (2), we study laser-driven\nspin currents in F|Pt stacks where F consists of model materials with different\ndegrees of electrical conductivity. For the magnetic insulators YIG, GIG and\nmaghemite, identical dynamics is observed. It arises from the THz interfacial\nspin Seebeck effect (SSE), is fully determined by the relaxation of the\nelectrons in the metal layer and provides an estimate of the spin-mixing\nconductance of the GIG/Pt interface. Remarkably, in the half-metallic\nferrimagnet Fe3O4 (magnetite), our measurements reveal two spin-current\ncomponents with opposite direction. The slower, positive component exhibits SSE\ndynamics and is assigned to torque-type magnon excitation of the A- and B-spin\nsublattices of Fe3O4. The faster, negative component arises from the\npyro-spintronic effect and can consistently be assigned to ultrafast\ndemagnetization of e-sublattice minority-spin hopping electrons. This\nobservation supports the magneto-electronic model of Fe3O4. In general, our\nresults provide a new route to the contact-free separation of torque- and\nconduction-electron-mediated spin currents.",
        "positive": "Controllable freezing of the nuclear spin bath in a single-atom spin\n  qubit: The quantum coherence and gate fidelity of electron spin qubits in\nsemiconductors is often limited by noise arising from coupling to a bath of\nnuclear spins. Isotopic enrichment of spin-zero nuclei such as $^{28}$Si has\nled to spectacular improvements of the dephasing time $T_2^*$ which,\nsurprisingly, can extend two orders of magnitude beyond theoretical\nexpectations. Using a single-atom $^{31}$P qubit in enriched $^{28}$Si, we show\nthat the abnormally long $T_2^*$ is due to the controllable freezing of the\ndynamics of the residual $^{29}$Si nuclei close to the donor. Our conclusions\nare supported by a nearly parameter-free modeling of the $^{29}$Si nuclear spin\ndynamics, which reveals the degree of back-action provided by the electron spin\nas it interacts with the nuclear bath. This study clarifies the limits of\nergodic assumptions in analyzing many-body spin-problems under conditions of\nstrong, frequent measurement, and provides novel strategies for maximizing\ncoherence and gate fidelity of spin qubits in semiconductors."
    },
    {
        "anchor": "Rapid adiabatic gating for capacitively coupled quantum dot hybrid\n  qubits without barrier control: We theoretically examine the capacitive coupling between two quantum dot\nhybrid qubits, each consisting of three electrons in a double quantum dot, as a\nfunction of the energy detuning of the double dot potentials. We show that a\nshaped detuning pulse can produce a two-qubit maximally entangling operation in\n$\\sim$50ns without having to simultaneously change tunnel couplings.\nSimulations of the entangling operation in the presence of experimentally\nrealistic charge noise yield two-qubit fidelities over 90%.",
        "positive": "Fine energy splitting of overlapping Andreev bound states in\n  multi-terminal superconducting nanostructures: The recent proposals of experiments with single Andreev bound states make\nrelevant a detailed analysis of these states in multi-terminal superconducting\nnanostructures. We evaluate the energy splitting of degenerate Andreev bound\nstates, that overlap in a superconducting lead, and find that the splitting is\nreduced in comparison with their energy by a small factor $\\sqrt{R G_Q}$, $R\nG_Q$ being the dimensionless resistance of the overlap region in the normal\nstate. This permits quantum manipulation of the quasiparticles in these states.\nWe provide a simple scheme of such manipulation."
    },
    {
        "anchor": "Estimation of electron temperature in heated metallic nanoparticle: A method is proposed for determining the temperature of hot electrons in a\nmetallic nanoparticle embedded in a dielectric matrix under ultrashort laser\npulses irradiation. The amplitude and power of the longitudinal spherical\nacoustic oscillations as functions of density and elastic properties of the\nmedium, the laser pulse duration, the electron temperature, radii of particles,\nand the electron-phonon coupling constant are obtained. The efficiency of the\nelectron energy transfer from heated noble nanoparticles to a surrounding\nenvironment is estimated for different electron temperatures.",
        "positive": "Quantum fluctuations and phase coherence in superconducting nanowires: Quantum behavior of superconducting nanowires may essentially depend on the\nemployed experimental setup. Here we investigate a setup that enables passing\nequilibrium supercurrent across an arbitrary segment of the wire without\nrestricting fluctuations of its superconducting phase. The low temperature\nphysics of the system is determined by a combined effect of collective\nsound-like plasma excitations and quantum phase slips. At $T=0$ the wire\nexhibits two quantum phase transitions, both being controlled by the\ndimensionless wire impedance $g$. While thicker wires with $g>16$ stay\nsuperconducting, in thinnest wires with $g<2$ the supercurrent is totally\ndestroyed by quantum fluctuations. The intermediate phase with $2<g<16$ is\ncharacterized by two different correlation lengths demonstrating\nsuperconducting-like behavior at shorter scales combined with vanishing\nsuperconducting response in the long scale limit."
    },
    {
        "anchor": "Even-odd parity effects in conductance and shot noise of metal-atomic\n  wire-metal(superconducting) junctions: In this paper, we study the conductance and shot noise in transport through a\nmulti-site system in a two terminal configuration. The dependence of the\ntransport on the number of atoms in the atomic wire is investigated using a\ntight-binding Hamiltonian and the nonequilibrium Green's function method. In\naddition to reproducing the even-odd behavior in the transmission probability\nat the Fermi energy or the linear response conductance in the normal-atomic\nwire-normal metallic(NAN) junctions, we find the following: (i) The shot noise\nis larger in the even-numbered atomic wire than in the odd-numbered wire. (ii)\nThe Andreev conductance displays the same even-odd parity effects in the\nnormal-atomic wire-superconducting(NAS) junctions. In general, the conductance\nis higher in the odd-numbered atomic wire than in the even-numbered wire. When\nthe number of sites ($N$) is odd and the atomic wire is mirror symmetric with\nrespect to the center of the atomic wire, the conductance does not depend on\nthe details of the hopping matrices in the atomic wire, but is solely\ndetermined by the coupling strength to the two leads. When $N$ is even, the\nconductance is sensitive to the values of the hopping matrices.",
        "positive": "Configurations of structural defects in graphene and their effects on\n  its transport properties: The chapter combines analytical (statistical-thermodynamic and kinetic) with\nnumerical (Kubo-Greenwood-formalism-based) approaches used to ascertain an\ninfluence of the configurations of point (impurities, vacancies) and line\n(grain boundaries, atomic steps) defects on the charge transport in graphene.\nPossible substitutional and interstitial graphene-based superstructures are\npredicted and described. The arrangements of dopants over sites or interstices\nrelated with interatomic-interaction energies governing the configurations of\nimpurities. Depending on whether the interatomic interactions are short- or\nlong-range, the low-temperature stability diagrams in terms of\ninteraction-energy parameters are obtained. The dominance of intersublattice\ninteractions in competition with intrasublattice ones results in a nonmonotony\nof ordering-process kinetics. Spatial correlations of impurities do not affect\nthe electronic conductivity of graphene for the most important\nexperimentally-relevant cases of point defects, neutral adatoms and screened\ncharged impurities, while atomic ordering can give rise in the conductivity up\nto tens times for weak and strong short-range potentials. There is no ordering\neffect manifestation for long-range potentials. The anisotropy of the\nconductivity along and across the line defects is revealed and gives rise in\nthe conductivity of graphene with correlated line defects as compared with the\ncase of random ones. Simultaneously correlated (and/or ordered) point and line\ndefects in graphene can give rise in the conductivity up to hundreds times vs.\ntheir random distribution. On an example of different B or N doping\nconfigurations in graphene, results from the Kubo-Greenwood approach are\ncompared with those obtained from DFT method."
    },
    {
        "anchor": "Accuracy of transfer matrix approaches for solving the effective mass\n  Schr\u00f6dinger equation: The accuracy of different transfer matrix approaches, widely used to solve\nthe stationary effective mass Schr\\\"{o}dinger equation for arbitrary\none-dimensional potentials, is investigated analytically and numerically. Both\nthe case of a constant and a position dependent effective mass are considered.\nComparisons with a finite difference method are also performed. Based on\nanalytical model potentials as well as self-consistent Schr\\\"{o}dinger-Poisson\nsimulations of a heterostructure device, it is shown that a symmetrized\ntransfer matrix approach yields a similar accuracy as the Airy function method\nat a significantly reduced numerical cost, moreover avoiding the numerical\nproblems associated with Airy functions.",
        "positive": "Light-induced bound electron states in two-dimensional systems:\n  Contribution to electron transport: In two-dimensional (2D) electron systems, an off-resonant high-frequency\ncircularly polarized electromagnetic field can induce the quasi-stationary\nbound electron states of repulsive scatterers. As a consequence, the resonant\nscattering of conduction electrons through the quasi-stationary states and the\ncapture of conduction electrons by the states appear. The present theory\ndescribes the transport properties of 2D electron gas irradiated by a\ncircularly polarized light, which are modified by these processes.\nParticularly, it is demonstrated that irradiation of 2D electron systems by the\noff-resonant field results in the quantum correction to conductivity of\nresonant kind."
    },
    {
        "anchor": "Analogies in electronic properties of graphene wormhole and perturbed\n  nanocylinder: The electronic properties of the wormhole and the perturbed nanocylinder will\nbe investigated using two different methods: the continuum gauge field-theory\nmodel which deals with the contin- uum approximation of the surface and the\nHaydock recursion method which transforms the surface into simplier structure\nand deals with the nearest-neighbor interactions. Furthermore, the changes of\nthe electronic properties will be investigated for the case of enclosing the\nappropriate structure and possible substitutes for the encloser will be\nderived. Finally, possible character of the electron flux will be derived from\nthe model based on the multiwalled nanotubes.",
        "positive": "Spin and charge thermopower effects in the ferromagnetic graphene\n  junction: Using wave function matching approach and employing the Landauer-Buttiker\nformula a ferromagnetic graphene junction with a temperature gradient across\nthe system, is studied. We calculate the thermally induced charge and spin\ncurrent as well as the thermoelectric voltage (Seebeck effect) in the linear\nand nonlinear regimes. Our calculation revealed that due to the electron-hole\nsymmetry, the charge Seebeck coefficient is, for an undoped magnetic graphene,\nan odd function of chemical potential while the spin Seebeck coefficient is an\neven function regardless of the temperature gradient and junction length. We\nhave also found with an accurate tuning external parameter, namely the exchange\nfiled and gate voltage, the temperature gradient across the junction drives a\npure spin current without accompanying the charge current. Another important\ncharacteristic of thermoelectric transport, thermally induced current in the\nnonlinear regime, is examined. It would be our main finding that with\nincreasing thermal gradient applied to the junction the spin and charge\nthermovoltages decrease and even become zero for non-zero temperature bias."
    },
    {
        "anchor": "Resonant scattering due to adatoms in graphene: top, bridge, and hollow\n  position: We present a theoretical study of resonance characteristics in graphene from\nadatoms with $s$ or $p_z$ character binding in top, bridge, and hollow\npositions. The adatoms are described by two tight-binding parameters: onsite\nenergy and hybridization strength. We explore a wide range of different\nmagnitudes of these parameters by employing T-matrix calculations in the single\nadatom limit and by tight-binding supercell calculations for dilute adatom\ncoverage. We calculate the density of states and the momentum relaxation rate\nand extract the resonance level and resonance width. Top position with large\nhybridization strength or, equivalently, small onsite energy, induces\nresonances close to zero energy. Bridge position, compared to top, is more\nsensitive to variation in the orbital tight-binding parameters. Resonances\nwithin the experimentally relevant energy window are found mainly for bridge\nadatoms with negative onsite energies. The effect of resonances from top and\nbridge position on the density of states and momentum relaxation rate is\ncomparable and both positions give rise to power-law decay of the resonant\nstate in graphene. Hollow position with $s$ orbital character is affected from\ndestructive interference which is seen from very narrow resonance peaks in the\ndensity of states and momentum relaxation rate. The resonant state shows no\nclear tendency to power-law decay around the impurity and its magnitude\ndecreases strongly with lowering the adatom content in the supercell\ncalculations. This is in contrast to top and bridge position. We conclude our\nstudy with a comparison to models of point-like vacancies and strong midgap\nscatterers. The latter model gives rise to significantly higher momentum\nrelaxation rates than caused by single adatoms.",
        "positive": "Floquet topological transitions in a driven one-dimensional topological\n  insulator: The Su-Schrieffer-Heeger model of polyacetylene is a paradigmatic Hamiltonian\nexhibiting non-trivial edge states. By using Floquet theory we study how the\nspectrum of this one-dimensional topological insulator is affected by a\ntime-dependent potential. In particular, we evidence the competition among\ndifferent photon-assisted processes and the native topology of the unperturbed\nHamiltonian to settle the resulting topology at different driving frequencies.\nWhile some regions of the quasienergy spectrum develop new gaps hosting Floquet\nedge states, the native gap can be dramatically reduced and the original edge\nstates may be destroyed or replaced by new Floquet edge states. Our study is\ncomplemented by an analysis of Zak phase applied to the Floquet bands. Besides\nserving as a simple example for understanding the physics of driven topological\nphases, our results could find a promising test-ground in cold matter\nexperiments."
    },
    {
        "anchor": "Shot noise in the edge states of 2D topological insulators: We calculate the resistance and shot noise in the edge states of a 2D\ntopological insulator that result from the exchange of electrons between these\nstates and conducting puddles in the bulk of the insulator. The two limiting\ncases where the energy relaxation is either absent or very strong are\nconsidered. A finite time of spin relaxation in the puddles is introduced\nphenomenologically. Depending on this time and on the strength of coupling\nbetween the edge states and the puddles, the Fano factor $F=S_I/2eI$ ranges\nfrom 0 to 1/3, which is in an agreement with the available experimental data.",
        "positive": "Single Particle Transport in Two-dimensional Heterojunction Interlayer\n  Tunneling Field Effect Transistor: The single particle tunneling in a vertical stack consisting of monolayers of\ntwo-dimensional semiconductors is studied theoretically and its application to\na novel Two-dimensional Heterojunction Interlayer Tunneling Field Effect\nTransistor (Thin-TFET) is proposed and described. The tunneling current is\ncalculated by using a formalism based on the Bardeen's transfer Hamiltonian,\nand including a semi-classical treatment of scattering and energy broadening\neffects. The misalignment between the two 2D materials is also studied and\nfound to influence the magnitude of the tunneling current, but have a modest\nimpact on its gate voltage dependence. Our simulation results suggest that the\nThin-TFETs can achieve very steep subthreshold swing, whose lower limit is\nultimately set by the band tails in the energy gaps of the 2D materials\nproduced by energy broadening. The Thin-TFET is thus very promising as a low\nvoltage, low energy solid state electronic switch."
    },
    {
        "anchor": "On Pendry's effective electron mass: In 1996, J. Pendry, an English theoretical physicist put forward an idea\nabout the dependence of the effective electron mass on the magnetic field,\nwhile interpreting the dielectric response of metal wire mesh structures. The\nidea was based on the well-known relation between the kinematic and canonical\nmomenta of a charged particle moving in the magnetic field. In this paper,\nproceeding from the universal character of that relation, the applicability of\nPendry's effective electron mass $m_{\\text{eff}}$ to the problem of electrons\nin metal mesh structures, as well as to a wide class of problems for charges\nmoving in the magnetic field, has been examined. The general properties of\n$m_{\\text{eff}}$ following directly from its definition were found, and an\nanalogy between the effective electron mass $m_{\\text{eff}}$ and $m^{\\ast}$\nknown in the solid-state theory was established. A physical interpretation of\n$m_{\\text{eff}}$ was proposed. It was demonstrated in several examples that,\ndespite the generality of the defining relation for the effective mass\n$m_{\\text{eff}}$, the use of $m_{\\text{eff}}$ beyond the problem of the\ndielectric response of metal wire mesh structures leads to incorrect results.",
        "positive": "Analogs of quantum Hall effect edge states in photonic crystals: \"Photonic crystals\" built with time-reversal-symmetry-breaking Faraday-effect\nmedia can exhibit \"chiral\" edge modes that propagate unidirectionally along\nboundaries across which the Faraday axis reverses. These modes are precise\nanalogs of the electronic edge states of quantum Hall effect (QHE) systems, and\nare also immune to backscattering and localization by disorder. The \"Berry\ncurvature\" of the photonic bands plays a role analogous to that of the magnetic\nfield in the QHE. Explicit calculations demonstrating the existence of such\nunidirectionally-propagating photonic edge states are presented."
    },
    {
        "anchor": "Conditions for Vanishing Central-well Population in Triple-well\n  Adiabatic Transport: Analytical expressions are derived for coherent tunneling via adiabatic\npassage (CTAP) in a triple well system with negligible central-well population\nat all times during the transfer. It is shown that a manipulation of the depths\nof the extreme-wells, correlated with the time variation of the\n\\emph{non-adjacent} barriers is essential for maintaining vanishing population\nof the central well. The validity of our conditions are demonstrated with a\nnumerical solution of the time-dependent Schr\\\"{o}dinger equation. The transfer\nprocess is interpreted in terms of a current through the central well.",
        "positive": "De Haas-van Alphen oscillations near the Lifshitz transition from two\n  electron pockets to one electron pocket in the two-dimensional Dirac fermion\n  systems: We theoretically study the de Haas-van Alphen (dHvA) oscillations in the\nsystem with changing the topology of the Fermi surface (the Lifshitz\ntransition) by electron dopings. We employ the two-dimensional tight binding\nmodel for $\\alpha$-(BEDT-TTF)$_2$I$_3$ under pressure which has two Dirac\npoints in the first Brillouin zone. When this system is slightly doped, there\nexists two closed Fermi surfaces with the same area and the dHvA oscillations\nbecome saw-tooth pattern or inversed saw-tooth pattern for both cases of fixed\nelectron filling ($\\nu$) or fixed chemical potential ($\\mu$) with respect to\nthe magnetic field, respectively. By increasing dopings, the system approaches\nthe Lifshitz transition, where two closed Fermi surfaces are close each other.\nThen, we find that the pattern of the dHvA oscillations changes. A jump of the\nmagnetization appears at the center of the fundamental period and its magnitude\nincreases in the case of the fixed electron filling, while a jump is separated\ninto a pair of jumps and its separation becomes large in the case of the fixed\nchemical potential. This is due to the lifting of double degeneracy in the\nLandau levels. Since this lifting is seen in the two-dimensional Dirac fermion\nsystem with two Dirac points, the obtained results in this study can be applied\nto not only $\\alpha$-(BEDT-TTF)$_2$I$_3$ but also other materials with closely\nlocated Dirac points such as graphene under the uniaxial strain, in black\nphosphorus, twisted bilayer graphene, and so on."
    },
    {
        "anchor": "NMR Response of Nuclear Spin Helix in Quantum Wires with Hyperfine and\n  Spin-Orbit Interaction: We calculate the nuclear magnetic resonance (NMR) response of a quantum wire\nwhere at low temperature a self-sustained electron-nuclear spin order is\ncreated. Our model includes the electron mediated Ruderman-Kittel-Kasuya-Yosida\n(RKKY) exchange, electron spin-orbit interactions, nuclear dipolar\ninteractions, and the static and oscillating NMR fields, all of which play an\nessential role. The paramagnet to helimagnet transition in the nuclear system\nis reflected in an unusual response: it absorbs at a frequency given by the\ninternal RKKY exchange field, rather than the external static field, whereas\nthe latter leads to a splitting of the resonance peak.",
        "positive": "Excitonic Absorption Signatures of Twisted Bilayer WSe$_{2}$ by Electron\n  Energy-Loss Spectroscopy: Moir\\'{e} twist angle underpins the interlayer interaction of excitons in\ntwisted van der Waals hetero- and homo-structures. The influence of twist angle\non the excitonic absorption of twisted bilayer tungsten diselenide (WSe$_{2}$)\nhas been investigated using electron energy-loss spectroscopy.\nAtomic-resolution imaging by scanning transmission electron microscopy was used\nto determine key structural parameters, including the nanoscale measurement of\nthe relative twist angle and stacking order. Detailed spectral analysis\nrevealed a pronounced blueshift in the high-energy excitonic peak C with\nincreasing twist angle, up to 200 meV when compared to the AA$^{\\prime}$\nstacking. The experimental findings have been discussed relative to\nfirst-principle calculations of the dielectric response of the AA$^{\\prime}$\nstacked bilayer WSe$_{2}$ as compared to monolayer WSe$_{2}$ by employing the\n\\textit{GW} plus Bethe-Salpeter equation (BSE) approaches, resolving the origin\nof higher energy spectral features from ensembles of excitonic transitions, and\nthus any discrepancies between previous calculations. Furthermore, the\nelectronic structure of moir\\'{e} supercells spanning twist angles of\n$\\sim$9.5-46.5$^{\\circ}$ calculated by density functional theory (DFT) were\nunfolded, showing an uplifting of the conduction band minimum near the $Q$\npoint and minimal change in the upper valence band concurrently. The combined\nexperiment/theory investigation provides valuable insight into the physical\norigins of high-energy absorption resonances in twisted bilayers, which enables\nto track the evolution of interlayer coupling from tuning of the exciton C\ntransitions by absorption spectroscopy."
    },
    {
        "anchor": "Ultrafast transmission electron microscopy using a laser-driven field\n  emitter: femtosecond resolution with a high coherence electron beam: We present the development of the first ultrafast transmission electron\nmicroscope (UTEM) driven by localized photoemission from a field emitter\ncathode. We describe the implementation of the instrument, the photoemitter\nconcept and the quantitative electron beam parameters achieved. Establishing a\nnew source for ultrafast TEM, the G\\\"ottingen UTEM employs nano-localized\nlinear photoemission from a Schottky emitter, which enables operation with\nfreely tunable temporal structure, from continuous wave to femtosecond pulsed\nmode. Using this emission mechanism, we achieve record pulse properties in\nultrafast electron microscopy of 9 {\\AA} focused beam diameter, 200 fs pulse\nduration and 0.6 eV energy width. We illustrate the possibility to conduct\nultrafast imaging, diffraction, holography and spectroscopy with this\ninstrument and also discuss opportunities to harness quantum coherent\ninteractions between intense laser fields and free electron beams.",
        "positive": "Surface dominated transport in single crystalline nanoflake devices of\n  topological insulator Bi1.5Sb0.5Te1.8Se1.2: We report experimental evidence of surface dominated transport in single\ncrystalline nanoflake devices of topological insulator Bi1.5Sb0.5Te1.8Se1.2.\nThe resistivity measurements show dramatic difference between the nanoflake\ndevices and bulk single crystal. The resistivity and Hall analysis based on a\ntwo-channel model indicates that ~99% surface transport contribution can be\nrealized in 200 nm thick BSTS nanoflake devices. Using standard bottom gate\nwith SiO2 as a dielectric layer, pronounced ambipolar electric field effect was\nobserved in devices fabricated with flakes of 100 - 200 nm thick. Moreover,\nangle-dependent magneto-resistances of a nanoflake device with thickness of 596\nnm are fitted to a universal curve for the perpendicular component of the\napplied magnetic field. The value of phase coherence length obtained from 2D\nweak antilocalization fitting further confirmed the surface dominated\ntransport. Our results open a path for realization of novel electric and\nspintronic devices based on the topological helical surface states."
    },
    {
        "anchor": "Fermi-liquid regime of the mesoscopic Kondo problem: We consider the low temperature regime of the mesoscopic Kondo problem, and\nin particular the relevance of a Fermi-liquid description of this regime. Using\ntwo complementary approaches -- a mean field slave fermion approximation on the\none hand and a Fermi-liquid description \"\\`a la Nozi\\`eres\" supplemented by an\nargument of separation of scale on the other hand -- we show that they both\nlead to (essentially) the same quasi-particle spectra, providing in this way a\nstrong indication that they both give the correct physics of this regime.",
        "positive": "Microwave-free dynamic nuclear polarization via sudden thermal jumps: Dynamic Nuclear Polarization (DNP) presently stands as the preferred strategy\nto enhance the sensitivity of nuclear magnetic resonance measurements, but its\napplication relies on the use of high-frequency microwave to manipulate\nelectron spins, an increasingly demanding task as the applied magnetic field\ngrows. Here we investigate the dynamics of a system hosting a polarizing agent\nformed by two distinct paramagnetic centers near a level anti-crossing. We\ntheoretically show that nuclear spins polarize efficiently under a cyclic\nprotocol that combines alternating thermal jumps and radio-frequency pulses\nconnecting hybrid states with opposite nuclear and electronic spin alignment.\nCentral to this process is the difference between the spin-lattice relaxation\ntimes of either electron spin species, transiently driving the electronic spin\nbath out of equilibrium after each thermal jump. Without the need for microwave\nexcitation, this route to enhanced nuclear polarization may prove convenient,\nparticularly if the polarizing agent is designed to feature electronic level\nanti-crossings at high magnetic fields."
    },
    {
        "anchor": "Anomalous attenuation of piezoacoustic surface waves by liquid helium\n  thin films: We report on the observation of an anomalously high attenuation of high\nfrequency surface acoustic waves by thin films of liquid $^{4}$He. The\npiezoelectric acoustic waves propagate along the surface of a lithium niobate\nsubstrate, which is coated with varying amounts of liquid helium. When the\nthickness of the helium layer is much larger than the wavelength of the surface\nacoustic wave on the substrate its attenuation is dominated by the excitation\nof compressional waves into the liquid, in good agreement with theory and\nprevious measurements. However, for sufficiently thin helium coverage, we find\nthat the acoustic wave attenuation is significantly increased beyond that\nmeasured with the substrate submerged in bulk liquid. Possible mechanisms for\nthis enhanced attenuation are discussed.",
        "positive": "Valley spin-acoustic resonance in MoS${\\bf _2}$ monolayers: The band structure of a monolayer MoS$_2$ comprises of spin-split subbands,\nowing to the mutual presence of broken inversion symmetry and strong spin-orbit\ncoupling. In the conduction band, spin-valley coupled subbands cross each other\nat finite momenta, and they are valley-degenerate. When exposed to surface\nacoustic waves, the emerging strain-induced effective magnetic field can give\nrise to spin-flip transitions between the spin-split subbands in the vicinity\nof subbands crossing point, resulting in the emergence of a spin-acoustic\nresonance and the acoustoelectric current. An external magnetic field breaks\nthe valley degeneracy resulting in the valley-selective splitting of\nspin-acoustic resonances both in surface acoustic wave absorption and\nacoustoelectric current."
    },
    {
        "anchor": "Quantum Dynamics of a Josephson Junction-Driven Cavity Mode System in\n  the Presence of Voltage Bias Noise: We give a semiclassical analysis of the average photon number as well as\nphoton number variance (Fano factor $F$) for a Josephson-junction (JJ) embedded\nmicrowave cavity system, where the JJ is subject to a fluctuating (i.e. noisy)\nbias voltage with finite dc average. Through the ac Josephson effect, the dc\nvoltage bias drives the effectively nonlinear microwave cavity mode into an\namplitude squeezed state ($F<1$), as has been established previously [A. D.\nArmour, et al., Phys. Rev. Lett. 111, 247001 (2013)], but bias noise acts to\ndegrade this squeezing. We find that the sensitivity of the Fano factor to bias\nvoltage noise depends qualitatively on which stable fixed point regime the\nsystem is in for the corresponding classical nonlinear steady state dynamics.\nFurthermore, we show that the impact of voltage bias noise is most significant\nwhen the cavity is excited to states with large average photon number.",
        "positive": "Relaxation of Josephson qubits due to strong coupling to two-level\n  systems: We investigate the energy relaxation (T1) process of a qubit coupled to a\nbath of dissipative two-level fluctuators (TLF). We consider the fluctuators\nstrongly coupled to the qubit both in the limit of spectrally separated single\nTLF's as well as in the limit of spectrally dense TLF's. We conclude that the\navoided level crossings, usually attributed to very strongly coupled single\nTLF's, could also be caused by many weakly coupled spectrally dense\nfluctuators."
    },
    {
        "anchor": "Micromagnetic view on ultrafast magnon generation by femtosecond spin\n  current pulses: In this Article we discuss a micromagnetic modelling approach to describe the\nultrafast spin-transfer torque excitation of coherent and incoherent magnons on\nthe nanoscale. Implementing the action of a femtosecond spin current pulse\nentering an orthogonally magnetized thin ferromagnetic film, we reproduce\nrecent experimental results and reveal the factors responsible for the unequal\nexcitation efficiency of various spin waves. Our findings are in an excellent\nagreement with the results of an analytical description of spin-wave excitation\nbased on classical kinetic equations. Furthermore, we suggest an experimental\ndesign allowing for the excitation of laterally propagating spin waves beyond\nthe optical diffraction limit. Our findings demonstrate that the classical\nmicromagnetic picture retains its predictive and interpretative power on\nfemtosecond temporal and nanometer spatial scales.",
        "positive": "Quantum waveguides with a lateral semitransparent barrier: spectral and\n  scattering properties: We consider a quantum particle in a waveguide which consists of an infinite\nstraight Dirichlet strip divided by a thin semitransparent barrier on a line\nparallel to the walls which is modeled by a $\\delta$ potential. We show that if\nthe coupling strength of the latter is modified locally, i.e. it reaches the\nsame asymptotic value in both directions along the line, there is always a\nbound state below the bottom of the essential spectrum provided the effective\ncoupling function is attractive in the mean. The eigenvalues and\neigenfunctions, as well as the scattering matrix for energies above the\nthreshold, are found numerically by the mode-matching technique. In particular,\nwe discuss the rate at which the ground-state energy emerges from the continuum\nand properties of the nodal lines. Finally, we investigate a system with a\nmodified geometry: an infinite cylindrical surface threaded by a homogeneous\nmagnetic field parallel to the cylinder axis. The motion on the cylinder is\nagain constrained by a semitransparent barrier imposed on a ``seam'' parallel\nto the axis."
    },
    {
        "anchor": "Multiple asymmetric couplings induced unconventional corner mode in\n  topolectrical circuits: We investigate the emergence of unconventional corner mode in a\ntwo-dimensional topolectrical circuits induced by asymmetric couplings. The\nnon-Hermitian skin effect of two kinked one-dimensional lattices with multiple\nasymmetric couplings are explored. Then we extend to the two-dimensional model,\nderive conditions for the non-Hermitian hybrid skin effect and show how the\ncorner modes are formed by non-reciprocal pumping based on one-dimensional\ntopological modes. We provide explicit electrical circuit setups for realizing\nour observations via realistic LTspice simulation. Moreover, we show the time\nvarying behaviors of voltage distributions to confirm our results. Our study\nmay help to extend the knowledge on building the topological corner modes in\nthe non-Hermitian presence.",
        "positive": "Time resolved X-ray Resonant Magnetic Scattering in reflection geometry: We present a new setup to measure element-selective magnetization dynamics\nusing the ALICE chamber (RSI \\textbf{74}, 4048 (2003)) at the BESSY II\nsynchrotron at the Helmholtz-Zentrum Berlin. A magnetic field pulse serves as\nexcitation, and the magnetization precession is probed by element selective\nX-ray Resonant Magnetic Scattering (XRMS). With the use of single bunch\ngenerated x-rays a temporal resolution well below 100 ps is reached. The setup\nis realized in reflection geometry and enables investigations of thin films\ndescribed here, multilayers, and laterally structured samples. The combination\nof the time resolved setup with a cryostat in the ALICE chamber will allow to\nconduct temperature-dependent studies of precessional magnetization dynamics\nand of damping constants over a large temperature range and for a large variety\nof systems in reflection geometry."
    },
    {
        "anchor": "Effect of confinement potential shape on exchange interaction in coupled\n  quantum dots: Exchange interaction has been studied for electrons in coupled quantum dots\n(QD's) by a configuration interaction method using confinement potentials with\ndifferent profiles. The confinement potential has been parametrized by a\ntwo-centre power-exponential function, which allows us to investigate various\ntypes of QD's described by either soft or hard potentials of different range.\nFor the soft (Gaussian) confinement potential the exchange energy decreases\nwith increasing interdot distance due to the decreasing interdot tunnelling.\nFor the hard (rectangular-like) confinement potential we have found a\nnon-monotonic behaviour of the exchange interaction as a function of distance\nbetween the confinement potential centres. In this case, the exchange\ninteraction energy exhibits a pronounced maximum for the confinement potential\nprofile which corresponds to the nanostructure composed of the small inner QD\nwith a deep potential well embedded in the large outer QD with a shallow\npotential well. This effect results from the strong localization of electrons\nin the inner QD, which leads to the large singlet-triplet splitting.\nImplications of this finding for quantum logic operations have been discussed.",
        "positive": "Valley Contrasting Magnetoluminescence in Monolayer MoS$_{2}$ Quantum\n  Hall Systems: The valley dependent optical selection rules in recently discovered monolayer\ngroup-VI transition metal dichalcogenides (TMDs) make possible optical control\nof valley polarization, a crucial step towards valleytronic applications.\nHowever, in presence of Landaul level(LL) quantization such selection rules are\ntaken over by selection rules between the LLs, which are not necessarily valley\ncontrasting. Using MoS$_{2}$ as an example we show that the spatial\ninversion-symmetry breaking results in unusual valley dependent inter-LL\nselection rules, which directly locks polarization to valley. We find a\nsystematic valley splitting for all Landau levels (LLs) in the quantum Hall\nregime, whose magnitude is linearly proportional to the magnetic field and in\ncomparable with the LL spacing. Consequently, unique plateau structures are\nfound in the optical Hall conductivity, which can be measured by the\nmagneto-optical Faraday rotations."
    },
    {
        "anchor": "Self consistent charge-current in a mesoscopic region attached to\n  superconductor leads: We investigate the behavior of a electric potential profile inside a\nmesoscopic region attached to a pair of superconducting leads. It turns out\nthat ${\\rm I}-V$ characteristic curves are strongly modified by this profile.\nIn addition, the electronic population in the mesoscopic region is affected by\nthe profile behavior. We discuss the single particle current and the mesoscopic\nelectronic population within the non-equilibrium Keldysh Green functions\ntechnique. The Keldysh technique results are further converted in a self\nconsistent field (SFC) problem by introducing potential profile modifications\nas proposed by Datta. Evaluation of ${\\rm I}-V$ characteristics are presented\nfor several values of the model parameters and comparison with current\nexperimental results are discussed.",
        "positive": "Geometric spin manipulation in semiconductor quantum dots: We propose a method to flip the spin completely by an adiabatic transport of\nquantum dots. We show that it is possible to flip the spin by inducing a\ngeometric phase on the spin state of a quantum dot. We estimate the geometric\nspin flip time (approximately 2 pico-sec) which turned out to be much shorter\nthan the experimentally reported decoherence time (approx. 100 nano-sec) that\nwould provide an alternative means of fliping the spin before reaching\ndecoherence. It is important that both the Rashba coupling and the Dresselhaus\ncoupling are present for inducing a phase necessary for spin flip. If one of\nthem is absent, the induced phase is trivial and irrelevant for spin-flip."
    },
    {
        "anchor": "Nonlinear $\u03c3$-Model in (2+1) dimensions: The nonlinear $\\sigma$-model in (2+1) dimensions admits topological\nconfigurations called skyrmions. The topological charge of skyrmions turn out\nto be the fermionic number and the fermionic current is dictated by the\nskyrmion field configuration. The peculiar feature of this model is that a Hopf\nterm introduced into the Lagrangian can lead to exotic spin and fractional\nstatistics.",
        "positive": "Coherence of resonant-tunneling transport in terahertz quantum-cascade\n  lasers: We develop simple density-matrix models to describe the role of coherence in\nresonant-tunneling (RT) transport of quantum-cascade lasers (QCLs).\nSpecifically, we investigate the effects of coherent coupling between the\nlasing levels with other levels on the transport properties and gain spectra.\nIn the first part of the paper, we use a three-level density-matrix model to\nobtain useful analytical expressions for current transport through the injector\nbarrier in a QCL. An expression for the slope discontinuity in the\ncurrent-voltage characteristics at the lasing threshold is derived. This value\nis shown to be a direct measure of the population inversion at threshold, and\ncontradicts the previously held belief of it being indicative of ratio of the\nlaser level lifetimes. In the second part of the paper, we use density matrices\nto compute the gain spectrum for a resonant-phonon terahertz QCL design. The\nlarge anticrossing of the doublet of lower radiative levels is reflected in a\nbroad gain linewidth due to a coherent RT assisted depopulation process. At\ncertain bias conditions, the gain spectrum exhibits double peaks which is\nsupported by experimental observations."
    },
    {
        "anchor": "Coherence and Indistinguishability of Single Electrons Emitted by\n  Independent Sources: The on-demand emission of coherent and indistinguishable electrons by\nindependent synchronized sources is a challenging task of quantum electronics,\nin particular regarding its application for quantum information processing.\nUsing two independent on-demand electron sources, we trigger the emission of\ntwo single-electron wavepackets at different inputs of an electronic\nbeamsplitter. Whereas classical particles would be randomly partitioned by the\nsplitter, we observe two-particle interferences resulting from quantum\nexchange. Both electrons, emitted in indistinguishable wavepackets with\nsynchronized arrival time on the splitter, exit in different outputs as\nrecorded by the low frequency current noise. The demonstration of two-electron\ninterference provides the possibility to manipulate coherent and\nindistinguishable single-electron wavepackets in quantum conductors.",
        "positive": "Interaction induced edge channel equilibration: The electronic distribution functions of two Coulomb coupled chiral edge\nstates forming a quasi-1D system with broken translation invariance are found\nusing the equation of motion approach. We find that relaxation and thereby\nenergy exchange between the two edge states is determined by the shot noise of\nthe edge states generated at a quantum point contact (QPC). In close vicinity\nto the QPC, we derive analytic expressions for the distribution functions. We\nfurther give an iterative procedure with which we can compute numerically the\ndistribution functions arbitrarily far away from the QPC. Our results are\ncompared with recent experiments of Le Sueur et al.."
    },
    {
        "anchor": "Quantum tomography of an entangled three-spin state in silicon: Quantum entanglement is a fundamental property of coherent quantum states and\nan essential resource for quantum computing. While two-qubit entanglement has\nbeen demonstrated for spins in silicon, creation of multipartite entanglement,\na first step toward implementing quantum error correction, has remained\nchallenging due to the difficulties in controlling a multi-qubit array, such as\ndevice disorder, magnetic and electrical noises and exacting exchange controls.\nHere, we show operation of a fully functional three-qubit array in silicon and\ngeneration of a three-qubit Greenberger-Horne-Zeilinger (GHZ) state. We obtain\na state fidelity of 88.0 percent by quantum state tomography, which witnesses a\ngenuine GHZ-class quantum entanglement that is not biseparable. Our result\nshows the potential of silicon-based qubit platform for demonstrations of\nmultiqubit quantum algorithms.",
        "positive": "Resolving the ultrafast dynamics of charge carriers in nanocomposites: Here we describe an optical method to determine the dynamics of optically\nexcited carriers in nanostructured composite samples. By combining pump-probe\ntime-resolved reflectivity with scattering measurements, we extract the\ncharacteristic times for charge carrier evolution. We use the 3D\nMaxwell-Garnett formulae, modified to include the Drude optical response, to\nmodel the results. The method, applied to hydrogenated amorphous silicon\ncontaining crystalline silicon nanoparticles, showed that the recombination\ntimes in the nanocrystals and in the matrix were ~4.9 ps and ~22 ps,\nrespectively. The charge transfer time between the crystals and the matrix was\n~4 ps."
    },
    {
        "anchor": "Photon absorption in twisted bilayer graphene: We investigate one- and two-photon absorption in twisted bilayer graphene\n(TBLG) by examining the effects of tuning the twist angle $ \\theta $ and the\nexcitation energy $ E_l $ on their corresponding absorption coefficients $\n\\alpha_{i=1,2}$. We find that $ \\alpha_1 $ shows distinct peaks as a function\nof $ E_l $ which correspond to the van Hove singularities (vHS) of TBLG. In\ncontrast to single- (SLG) and AB bilayer graphene (BLG), $ \\alpha_1 $ is\nsubstantially enhanced by $\\sim 2$ and $\\sim 1$ orders of magnitude,\nrespectively, in the visible range. On the other hand, $\\alpha_2 $ exhibits a\nremarkable increase of $\\sim 11$ and $\\sim 9$ orders of magnitude.\nInterestingly, as $\\theta$ increases, the resonant features exhibited by\n$\\alpha_{i=1,2}$ \\textit{vs.} $ E_l $ shift progressively from the infrared to\nthe visible. On doping TBLG, both $\\alpha_1 $ and $ \\alpha_2 $ remain\nessentially unchanged \\textit{vs.} $ E_l $ but with a minor red-shift in their\nresonant peaks. Additionally, we explore various polarization configurations\nfor TPA and determine the conditions under which $\\alpha_2$ becomes extremal.",
        "positive": "Universality of defect-skyrmion interaction profiles: Magnetic skyrmions are prime candidates for future spintronic devices.\nHowever, incorporating them as an entity for information technology hinges on\ntheir interaction with defects ubiquitous to any device. Here we map from\nfirst-principles, the energy-profile of single skyrmions interacting with\nsingle-atom impurities, establishing a generic shape as function of the\ndefect's electron filling. Depending on their chemical nature, foreign 3d and\n4d transition metal adatoms or surface-implanted defects can either repel or\npin skyrmions in PdFe/Ir(111) thin films, which we relate to the degree of\nfilling of bonding and anti-bonding electronic states inherent to the proximity\nof the non-collinear magnetic structure. Similarities with key concepts of bond\ntheories in catalysis and surface sciences imbue the universality of the shape\nof the interaction profile and the potential of predicting its interaction. The\nresulting fundamental understanding may give guidance for the design of devices\nwith surface-implanted defects to generate and control skyrmions."
    },
    {
        "anchor": "Theory of invariants-based formulation of ${\\bf k}\\cdot{\\bf p}$\n  Hamiltonians with application to strained zinc-blende crystals: Group theoretical methods and ${\\bf k}\\cdot{\\bf p}$ theory are combined to\ndetermine spin-dependent contributions to the effective conduction band\nHamiltonian. To obtain the constants in the effective Hamiltonian, in general\nall invariants of the Hamiltonian have to be determined. Hence, we present a\nsystematic approach to keep track of all possible invariants and apply it to\nthe ${\\bf k}\\cdot{\\bf p}$ Hamiltonian of crystals with zinc-blende symmetry, in\norder to obtain all possible contributions to effective quantities such as\neffective mass, g-factor and Dresselhaus constant. Further spin-dependent\ncontributions to the effective Hamiltonian arise in the presence of strain. In\nparticular, with regard to the constants $C_3$ and $D$ which describe\nspin-splitting linear in the components of ${\\bf k}$ and\n${\\boldsymbol\\varepsilon}$, considering all possible terms allowed by symmetry\nis crucial.",
        "positive": "Exceptional Topology of Non-Hermitian Systems: The current understanding of the role of topology in non-Hermitian (NH)\nsystems and its far-reaching physical consequences observable in a range of\ndissipative settings are reviewed. In particular, how the paramount and\ngenuinely NH concept of exceptional degeneracies, at which both eigenvalues and\neigenvectors coalesce, leads to phenomena drastically distinct from the\nfamiliar Hermitian realm is discussed. An immediate consequence is the\nubiquitous occurrence of nodal NH topological phases with concomitant open\nFermi-Seifert surfaces, where conventional band-touching points are replaced by\nthe aforementioned exceptional degeneracies. Furthermore, new notions of gapped\nphases including topological phases in single-band systems are detailed, and\nthe manner in which a given physical context may affect the symmetry-based\ntopological classification is clarified. A unique property of NH systems with\nrelevance beyond the field of topological phases consists of the anomalous\nrelation between bulk and boundary physics, stemming from the striking\nsensitivity of NH matrices to boundary conditions. Unifying several\ncomplementary insights recently reported in this context, a picture of\nintriguing phenomena such as the NH bulk-boundary correspondence and the NH\nskin effect is put together. Finally, applications of NH topology in both\nclassical systems including optical setups with gain and loss, electric\ncircuits,s and mechanical systems and genuine quantum systems such as\nelectronic transport settings at material junctions and dissipative cold-atom\nsetups are reviewed."
    },
    {
        "anchor": "Intrinsic non-magnetic $\u03c6_0$ Josephson junctions in twisted bilayer\n  graphene: Recent experiments have demonstrated the possibility to design highly\ncontrollable junctions on magic angle twisted bilayer graphene, enabling the\ntest of its superconducting transport properties. We show that the presence of\nchiral pairing in such devices manifests in the appearance of an anomalous\nJosephson effect ($\\phi_0$ behavior) even in the case of symmetric junctions\nand without requiring any magnetic materials or fields. Such behavior arises\nfrom the combination of chiral pairing and nontrivial topology of the twisted\nbilayer graphene band structure that can effectively break inversion symmetry.\nMoreover, we show that the $\\phi_0$ effect could be experimentally enhanced and\ncontrolled by electrostatic tuning of the junction transmission properties.",
        "positive": "Creation and Amplification of Electro-Magnon Solitons by Electric Field\n  in Nanostructured Multiferroics: We develop a theoretical description of electro-magnon solitons in a coupled\nferroelectric-ferromagnetic heterostructure. The solitons are considered in the\nweakly nonlinear limit as a modulation of plane waves corresponding to two,\nelectric- and magnetic-like branches in the spectrum. Emphasis is put on\nmagnetic-like envelope solitons that can be created by an alternating electric\nfield. It is shown also that the magnetic pulses can be amplified by an\nelectric field with a frequency close to the band edge of the magnetic branch."
    },
    {
        "anchor": "Flux period scaling in the Laughlin quasiparticle interferometer: We report experiments on electron interferometer devices in the quantum Hall\nregime, where edge channels circle a 2D electron island. The main confinement\nis produced by etch trenches, into which front gate metal is deposited. We find\na linear dependence of the Aharonov-Bohm period on gate voltage for electrons\n(integer filling f=1) and for Laughlin quasiparticles (fractional 2/5 embedded\nin 1/3). The capacitance of a large 2D electron island with respect to the\nfront gates is approximately proportional to the island radius. Comparing the\nexperimental data for the integer and the fractional fillings and for two\nsamples, we find the magnetic field period and its slope scale with the radius\nof the Aharonov-Bohm orbit. Analysis of the directly measured integer and\nfractional slope data allows to determine the interferometer area in the\nfractional regime, and thus the Laughlin quasiparticle flux period of 5h/e,\nwithin the experimental accuracy.",
        "positive": "A single electron transistor with quantum rings: We Have developed the concept of a new kind of single-electron transistor in\nwhich the transport of the electron through a quantum wire is controlled by\ncharged quantum rings. Using a 2D harmonic potential as the transverse\nconstraint, we numerically investigated the transport of the electron through\nthe wire. We have shown that in the low energy limit, for a suitable\nconfiguration of the rings, called the quadrupole configuration, we are able to\nadjust the conductance of the wire and therefore control the switching process."
    },
    {
        "anchor": "Large peak-to-valley ratio of negative-differential-conductance in\n  graphene p-n junctions: We investigate the transport characteristics of monolayer graphene p-n\njunctions by means of the non-equilibrium Green's function technique. It is\nshown that thanks to the high interband tunneling of chiral fermions and to a\nfinite bandgap opening when the inversion symmetry of graphene plane is broken,\na strong negative-differential-conductance behavior with peak-to-valley ratio\nas large as a few tens can be achieved even at room temperature. The dependence\nof this behavior on the device parameters such as the Fermi energy, the barrier\nheight, and the transition length is then discussed.",
        "positive": "Superfluidity of a rarefied gas of electron-hole pairs in a bilayer\n  system: The conditions of stability of the superfluid phase in double layer systems\nwith pairing of spatially separated electrons and holes in the low density\nlimit are studied. The general expression for the collective excitation\nspectrum is obtained. It is shown that under increase in the distance $d$\nbetween the layers the minimum emerges in the excitation spectrum. When d\nreaches the critical value the superfluid state becomes unstable relative to\nthe formation of a kind of the Wigner crystal state. The same instability\noccurs at fixed d under increase in the density of carries. It is established\nthat the critical distance and the critical density are related to each other\nby the inverse power function. The impact of the impurities on the temperature\nof the superfluid transition is investigated. The impact is found weak at the\nimpurity concentration smaller than the density of the pairs. It is shown that\nin the rarefied system the critical temperature T_c = 100 K can be reached."
    },
    {
        "anchor": "Chiral Luttinger liquids in graphene tuned by irradiation: We show that chiral co-propagating Luttinger liquids can be created and tuned\nby shining high frequency, circularly polarized light, normal to the layers,\nwith different polarizations on two sections of bilayer graphene. By virtue of\nthe broken time-reversal symmetry and the resulting mismatch of Chern number,\nthe one-dimensional chiral modes are localized along the domain wall where the\npolarization changes. Single layer graphene hosts a single chiral edge mode\nnear each Dirac node, whereas in bilayer graphene, there are two chiral modes\nnear each of the Dirac nodes. These modes, under a high-frequency drive,\nessentially have a static charge distribution and form a chiral Luttinger\nliquid under Coulomb interaction, which can be tuned by means of the driving\nparameters. We also note that unlike the Luttinger liquids created by\nelectrostatic confinement in bilayer graphene, here there is no\nback-scattering, and hence our wires along the node are stable to disorder.",
        "positive": "Rashba Torque Driven Domain Wall Motion in Magnetic Helices: Manipulation of the domain wall propagation in magnetic wires is a key\npractical task for a number of devices including racetrack memory and magnetic\nlogic. Recently, curvilinear effects emerged as an efficient mean to impact\nsubstantially the statics and dynamics of magnetic textures. Here, we\ndemonstrate that the curvilinear form of the exchange interaction of a magnetic\nhelix results in an effective anisotropy term and Dzyaloshinskii--Moriya\ninteraction with a complete set of Lifshitz invariants for a one-dimensional\nsystem. In contrast to their planar counterparts, the geometrically induced\nmodifications of the static magnetic texture of the domain walls in magnetic\nhelices offer unconventional means to control the wall dynamics relying on\nspin-orbit Rashba torque. The chiral symmetry breaking due to the\nDzyaloshinskii-Moriya interaction leads to the opposite directions of the\ndomain wall motion in left- or right-handed helices. Furthermore, for the\nmagnetic helices, the emergent effective anisotropy term and\nDzyaloshinskii-Moriya interaction can be attributed to the clear geometrical\nparameters like curvature and torsion offering intuitive understanding of the\ncomplex curvilinear effects in magnetism."
    },
    {
        "anchor": "Turbulence Hierarchy and Multifractality in the Integer Quantum Hall\n  Transition: We offer a new perspective to the problem of characterizing mesoscopic\nfluctuations in the inter-plateau region of the integer quantum Hall\ntransition. We found that longitudinal and transverse conductance fluctuations,\ngenerated by varying the external magnetic field within a microscopic model,\nare multifractal and lead to distributions of conductance increments\n(magnetoconductance) with heavy tails (intermittency) and signatures of a\nhierarchical structure (a cascade) in the corresponding stochastic process,\nakin to Kolmogorov's theory of fluid turbulence. We confirm this picture by\ninterpreting the stochastic process of the conductance increments in the\nframework of H-theory, which is a continuous-time stochastic approach that\nincorporates the basic features of Kolmogorov's theory. The multifractal\nanalysis of the conductance \"time series,\" combined with the H-theory formalism\nprovides, strong support for the overall characterization of mesoscopic\nfluctuations in the quantum Hall transition as a multifractal stochastic\nphenomenon with multiscale hierarchy, intermittency, and cascade effects.",
        "positive": "Hot Carrier-Assisted Intrinsic Photoresponse in Graphene: Graphene is a new material showing high promise in optoelectronics,\nphotonics, and energy-harvesting applications. However, the underlying physical\nmechanism of optoelectronic response has not been established. Here, we report\non the intrinsic optoelectronic response of high-quality dual-gated monolayer\nand bilayer graphene p-n junction devices. Local laser excitation at the p-n\ninterface leads to striking six-fold photovoltage patterns as a function of\nbottom- and top-gate voltages. These patterns, together with the measured\nspatial and density dependence of the photoresponse, provide strong evidence\nthat non-local hot-carrier transport, rather than the photovoltaic effect,\ndominates the intrinsic photoresponse in graphene. This novel regime, which\nfeatures a long-lived and spatially distributed hot carrier population, may\nopen the doorway for optoelectronic technologies exploiting efficient energy\ntransport at the nanoscale."
    },
    {
        "anchor": "Kaleidoscope of symmetry protected topological phases in one-dimensional\n  periodically modulated lattices: We identify the existence of various symmetry-protected topological states in\none-dimensional superlattices with periodically modulated hopping amplitudes or\non-site potentials, which can be characterized by the quantized Berry phase\n$\\pi$ or the emergence of a pair of degenerate boundary states. It is shown\nthat there may exist three types of topological phases, which are protected by\nthe inversion symmetry, the chiral symmetry, and both of them, respectively,\ndepending on the modulations, the odd or even modulation period. The connection\nbetween the hopping and potential modulations is also discussed. Furthermore,\nwe demonstrate that the topological phase protected by the inversion symmetry\ncan be realized in the interacting boson systems trapped in the same\nsuperlattices. The results are very possibly studied experimentally in the\nsuperlattice systems engineered with state-of-art technologies.",
        "positive": "Modelling and Optimising GaAs/Al(x)Ga(1-x)As Multiple Quantum Well Solar\n  Cells: The quantum well solar cell (QWSC) is a p - i - n solar cell with quantum\nwells in the intrinsic region. Previous work has shown that QWSCs have a\ngreater open circuit voltage (Voc) than would be provided by a cell with the\nquantum well effective bandgap. This suggests that the fundamental efficiency\nlimits of QWSCs are greater than those of single bandgap solar cells. The\nfollowing work investigates QWSCs in the GaAs/AlxGa1-xAs materials system. The\ndesign and optimisation of a QWSC in this system requires studies of the\nvoltage and current dependencies on the aluminium fraction. QWSCs with\ndifferent aluminium fractions have been studied and show an increasing Voc with\nincreasing barrier aluminium composition. The QE however decreases with\nincreasing aluminium composition. We develop a model of the QE to test novel\nQWSC designs with a view to minimising this problem. This work concentrates on\ntwo design changes. The first deals with com- positionally graded structures in\nwhich the bandgap varies with position. This bandgap variation introduces an\nquasi electric field which can be used to increase minority carrier collection\nin the low efficiency p and n layers. This technique also increases the light\nflux reaching the highly efficient depletion regions. The second design change\nconsists of coating the back of the cell with a mirror to exploit the portion\nof light which is not absorbed on the first pass. A model of the QE of\ncompositionally graded QWSC solar cells with back surface mirrors is developed\nin order to analyse the effect of these design changes. These changes are\nimplemented separately in a number of QWSC designs and the resulting\nexperimental data compared with the model. An optimised design is then\npresented."
    },
    {
        "anchor": "Non-equilibrium phonon transport in surface-roughness dominated\n  nanowires: Experimental observation of highly reduced thermal conductivity in\nsurface-roughness dominated silicon nanowires have generated renewed interest\nin low-dimensional thermoelectric devices. Using a previous work where the\nscattering of phonons from a rough surface is mapped to scattering from\nrandomly situated localized phonons in the bulk of a smooth nanowire, we\nconsider the thermal current across a nanowire for various strengths of surface\ndisorder. We use non-equilibrium Green's function techniques that allow us to\nevaluate the thermal current beyond the linear response regime, for arbitrary\ncold and hot temperatures of the two semi-infinite connecting leads. We show\nhow the surface-roughness affects the frequency dependence of the thermal\ncurrent, eventually leading to a temperature dependent reduction of the net\ncurrent at high temperatures. We use a universal disorder parameter to describe\nthe surface-roughness as has been proposed, and show that the dependence of the\nnet current on this parameter provides a natural explanation for the\nexperimentally observed differences between smooth vs rough surfaces. We argue\nthat a systematic study of the thermal current for different values of the\ntemperature difference between the two sides of a surface-roughness dominated\nnanowire for various strengths of disorder would help in our understanding of\nhow best to optimize the thermoelectric efficiency.",
        "positive": "All-electrical detection of the spin-charge conversion in nanodevices\n  based on SrTiO3 two-dimensional electron gases: The Magnetoelectric Spin-Orbit (MESO) technology aims to bring logic into\nmemory by combining a ferromagnet with a magnetoelectric (ME) element for\ninformation writing, and a spin-orbit (SO) element for information read-out\nthrough spin-charge conversion. Among candidate SO materials to achieve a large\nMESO output signal, oxide Rashba two-dimensional electron gases (2DEGs) have\nshown very large spin-charge conversion efficiencies, albeit mostly in\nspin-pumping experiments. Here, we report all-electrical spin-injection and\nspin-charge conversion experiments in nanoscale devices harnessing the inverse\nEdelstein effect of SrTiO3 2DEGs. We have designed, patterned and fabricated\nnanodevices in which a spin current injected from a cobalt layer into the 2DEG\nis converted into a charge current. We optimized the spin-charge conversion\nsignal by applying back-gate voltages, and studied its temperature evolution.\nWe further disentangled the inverse Edelstein contribution from spurious\neffects such as the planar Hall effect, the anomalous Hall effect or the\nanisotropic magnetoresistance. The combination of non-volatility and high\nenergy efficiency of these devices could potentially lead to new technology\nparadigms for beyond-CMOS computing architectures."
    },
    {
        "anchor": "Charge transport in ballistic multiprobe graphene structures: We study the the transport properties of multiterminal ballistic graphene\nsamples, concentrating on the conductance matrix, fluctuations and\ncross-correlations. Far away from Dirac point, the current is carried mostly by\npropagating modes and the results can be explained with the conventional\nsemiclassical picture familiar from ray optics, where electrons propagate along\na single direction before scattering or reaching the terminals. However, close\nto the Dirac point the transport is due to evanescent modes which do not have\nto follow a rectilinear path. As we show in this Letter, this property of the\nevanescent modes influences the conductance matrix. However, at best it can be\nobserved by measuring the cross correlations in an exchange Hanbury Brown-Twiss\nexperiment.",
        "positive": "Strongly correlated regimes in a double quantum-dot device: The transport properties of a double quantum-dot device with one of the dots\ncoupled to perfect conductors are analyzed using the numerical renormalization\ngroup technique and slave-boson mean-field theory. The coupling between the\ndots strongly influences the transport through the system leading to a\nnon-monotonic dependence of the conductance as a function of the temperature\nand the magnetic field. For small inter-dot coupling and parameters such that\nboth dots are in the Kondo regime, there is a two-stage screening of the dot's\nmagnetic moments that is reflected in the conductance. In an intermediate\ntemperature regime Kondo correlations develop on one of the dots and the\nconductance is enhanced. At low temperatures the Kondo effect takes place on\nthe second dot leading to a singlet ground state in which the conductance is\nstrongly suppressed."
    },
    {
        "anchor": "Mode Spectroscopy and Level Coupling in Ballistic Electron Waveguides: A tunable quantum point contact with modes occupied in both transverse\ndirections is studied by magnetotransport experiments. We use conductance\nquantization of the one-dimensional subbands as a tool to determine the mode\nspectrum. A magnetic field applied along the direction of the current flow\ncouples the modes. This can be described by an extension of the Darwin-Fock\nmodel. Anticrossings are observed as a function of the magnetic field, but not\nfor zero field or perpendicular field directions, indicating coupling of the\nsubbands due to nonparabolicity in the electrical confinement.",
        "positive": "In-plane anisotropy effect on critical transition field in nanogranular\n  films with perpendicular anisotropy: The influence of the in-plane anisotropy on the magnetization of a\nnanogranular film with perpendicular anisotropy has been studied. It is shown\nthat if a magnetic field is tilted with respect to the film normal, a critical\ntransition from the inhomogeneous magnetic state of granules with noncollinear\ndirections of their moments to the homogeneous one with parallel orientation of\ngranular magnetic moments takes place. The in-plane anisotropy is found to\naffect the angular dependence of the critical field. The ensemble of oriented\nbiaxial particles is theoretically described in the double-well potential\napproximation. Despite the biaxial magnetic anisotropy of particles, their\nensemble, if in the inhomogeneous state, is divided into two subensembles, with\nthe magnetic moments of particles being collinear in each of them. In the\ncritical field, a transition from the inhomogeneous state with two subensembles\ninto the homogeneous one takes place. The results of theoretical calculations\nare compared with experimental data for a nanogranular Co/Al2On film with\nperpendicular anisotropy containing 74.5 at.% Co, which exceeds the percolation\nthreshold. The magnetic moment of this film is a sum of two contributions: from\nnanogranules with biaxial anisotropy and a phase forming the percolation\ncluster. The magnetic properties of nanogranules, whose contribution is\nseparated from the total film magnetization, agree well with the calculation\ndata."
    },
    {
        "anchor": "Lattice Electrons on a Cylinder Surface in the Presence of Rational\n  Magnetic Flux and Disorder: We consider a disordered two-dimensional system of independent lattice\nelectrons in a perpendicular magnetic field with rigid confinement in one\ndirection and generalized periodic boundary conditions (GPBC) in the other\ndirection. The objects investigated numerically are the orbits in the plane\nspanned by the energy eigenvalues and the corresponding center of mass\ncoordinate in the confined direction, parameterized by the phase characterizing\nthe GPBC. The Kubo Hall conductivity is expressed in terms of the winding\nnumbers of these orbits. For vanishing disorder the spectrum of the system\nconsists of Harper bands with energy levels corresponding to the edge states\nwithin the band gaps. Disorder leads to broadening of the bands. For\nsufficiently large systems localized states occur in the band tails. We find\nthat within the mobility gaps of bulk states the Diophantine equation\ndetermines the value of the Hall conductivity as known for systems with torus\ngeometry (PBCs in both directions). Within the spectral bands of extended\nstates the Hall conductivity fluctuates strongly. For sufficiently large\nsystems the generic behavior of localization-delocalization transitions\ncharacteristic for the quantum Hall effect are recovered.",
        "positive": "Half-Quantized Helical Hinge Currents in Axion Insulators: We propose that half-quantized helical hinge currents manifest as the\nfingerprint of the axion insulator (AI). These helical hinge currents\nmicroscopically originate from the lateral Goos-H\\\"anchen (GH) shift of\nmassless side-surface Dirac electrons that are totally reflected from the\nhinges. Meanwhile, due to the presence of the massive top and bottom surfaces\nof the AI, the helical current induced by the GH shift is half-quantized. The\nsemiclassical wave packet analysis uncovers that the hinge current has a\ntopological origin and its half-quantization is robust to parameter changes.\nLastly, we propose an experimentally feasible six-terminal device to identify\nthe half-quantized hinge channels by measuring the nonreciprocal conductances.\nOur results advance the understanding of the non-trivial transport and\ntopological magnetoelectric responses in AIs."
    },
    {
        "anchor": "An orbitally derived single-atom magnetic memory: A single magnetic atom on a surface epitomizes the scaling limit for magnetic\ninformation storage. Indeed, recent work has shown that individual atomic spins\ncan exhibit magnetic remanence and be read out with spin-based methods,\ndemonstrating the fundamental requirements for magnetic memory. However, atomic\nspin memory has been only realized on thin insulating surfaces to date,\nremoving potential tunability via electronic gating or distance-dependent\nexchange-driven magnetic coupling. Here, we show a novel mechanism for\nsingle-atom magnetic information storage based on bistability in the orbital\npopulation, or so-called valency, of an individual Co atom on semiconducting\nblack phosphorus (BP). Distance-dependent screening from the BP surface\nstabilizes the two distinct valencies and enables us to electronically\nmanipulate the relative orbital population, total magnetic moment and spatial\ncharge density of an individual magnetic atom without a spin-dependent readout\nmechanism. Furthermore, we show that the strongly anisotropic wavefunction can\nbe used to locally tailor the switching dynamics between the two valencies.\nThis orbital memory derives stability from the energetic barrier to atomic\nrelaxation and demonstrates the potential for high-temperature single-atom\ninformation storage.",
        "positive": "Coupling of electron rotation with spin in semiconductors: Account of an intrinsic spin-orbit coupling in the valence bands of common\nsemiconductors yields the scalar spin-orbit-rotation term in the effective-mass\nHamiltonian of the conduction-band electron. This result is obtained within the\nmultiband envelope function approximation. Fundamentally, the\nspin-orbit-rotation coupling can be described in purely geometric terms as a\nconsequence of the difference in the Berry phase acquired by the components of\nthe spin-orbitally mixed Kramers-doublet during its cyclic evolution in the\nreciprocal momentum space."
    },
    {
        "anchor": "Effect of Landau quantization on linear magnetoresistance of\n  periodically modulated two-dimensional electron gas: The linear response of two-dimensional electron gas in a perpendicular\nmagnetic field in the presence of a spatially dependent classically smooth\nelectrostatic potential is studied theoretically, by application of the Kubo\nformula for nonlocal conductivity tensor. In the classical transport regime, a\ngeneral expression for the conductivity tensor through the correlation\nfunctions of the homogeneous electron gas is derived. The quantum transport\nregime, when Landau quantization is essential, is studied for the case of\nunidirectional periodic potential modulation. Apart from the Shubnikov-de Haas\noscillations, the resistivity can demonstrate quantum oscillations with larger\nperiods and smaller amplitudes, which survive when temperature increases. These\noscillations exist when the modulation amplitude considerably exceeds the\ncyclotron energy so the Landau subbands, formed out of the Landau levels by the\nmodulation potential, overlap in the energy domain. Both diagonal components of\nthe resistivity tensor demonstrate oscillations related to modification of the\ndensity of states by the modulation. In addition, the resistivity component\nperpendicular to the modulation axis, which is caused by the\nscattering-assisted hopping transport, shows another kind of oscillations\nrelated to enhancement of the hopping probability when the guiding center of\ncyclotron orbit shifts by the doubled cyclotron radius. It is suggested that\nsuch high-temperature oscillations can be detected under conditions when the\nmodulation period considerably exceeds the cyclotron radius.",
        "positive": "Graphene Electronic Structure in Charge Density Waves: We introduce the idea that the electronic band structure of a charge density\nwave system may mimic the electronic structure of graphene. In that case a\nclass of materials quite different from graphene might be opened up to exploit\ngraphene's remarkable electronic properties. The theory of such materials,\nalong with superconductivity, is based on the material's dynamical, rather than\nits static, properties. The charge density wave system turns out to have a\nnumber of requirements: (1) a specific wave geometry simply related to\ngraphene; (2) a self-consistency among the electrons that requires the net\nCoulomb and phonon-mediated parts of the electron-electron interactions to be\nattractive. We develop a model that leads to an analytical expression for the\ntotal energy in terms of the effective electron mass $\\mu$, the electron\ndensity $\\rho_0$, and the strength $\\tilde{\\nu}_{K}$ of the net\nelectron-electron interaction. For constant $\\mu>0$ and $\\rho_0$, we examine\nthe limitations set upon $\\tilde{\\nu}_{K}$ by self-consistency, stability, and\nthe approximation in the electronic state calculation, and find them to be\nmutually compatible. This demonstrates the viability of our model."
    },
    {
        "anchor": "Andreev-Klein reflection in graphene ferromagnet-superconductor\n  junctions: We show that Andreev reflection in a junction between ferromagnetic (F) and\nsuperconducting (S) graphene regions is fundamentally different from the common\nFS junctions. For a weakly doped F graphene with an exchange field $h$ larger\nthan its Fermi energy $E_{\\rm F}$, Andreev reflection of massless Dirac\nfermions is associated with a Klein tunneling through an exchange field p-n\nbarrier between two spin-split conduction and valence subbands. We find that\nthis Andreev-Klein process results in an enhancement of the subgap conductance\nof a graphene FS junction by $h$ up to the point at which the conductance at\nlow voltages $eV\\ll \\Delta$ is greater than its value for the corresponding\nnon-ferromagnetic junction. We also demonstrate that the Andreev reflection can\nbe of retro or specular types in both convergent and divergent ways with the\nreflection direction aligned, respectively, closer to and farther from the\nnormal to the junction as compared to the incidence direction.",
        "positive": "Supersonic flow and negative local resistance in hydrodynamic Dirac\n  electron nozzles: In clean Dirac electron systems such as graphene, electron-electron\ninteractions can dominate over other relaxation mechanisms such as phonon or\nimpurity scattering. It has been predicted that in this limit, collective\nelectron dynamics can be described by hydrodynamic equations. The prerequisites\nfor electron liquids are already fulfilled in current experiments and hints of\nelectron hydrodynamics have been identified in transport measurements. Here, we\nshow that a nozzle geometry, implemented for example in a graphene sample, can\ncause a transition from subsonic to supersonic flow and provides an interesting\nprobe for the hydrodynamic regime of Dirac electrons. In particular, we predict\ntwo distinct transport features that can be seen in the experimentally\nmeasurable voltage characteristics on the exit side of the nozzle: a pronounced\nnegative local resistance, and an abrupt change of the electrostatic potential\ninduced by an electron shock wave. Our results pave the way for an experimental\nidentification of supersonic hydrodynamic electron flow and for the\nexperimental study of electron shock waves."
    },
    {
        "anchor": "The Optical Properties and Plasmonics of Anisotropic 2-Dimensional\n  Materials: In the fast growing two-dimensional (2D) materials family, anisotropic 2D\nmaterials, with their intrinsic in-plane anisotropy, exhibit a great potential\nin optoelectronics. One such typical material is black phosphorus (BP), with a\nlayer-dependent and highly tunable band gap. Such intrinsic anisotropy adds a\nnew degree of freedom to the excitation, detection and control of light.\nParticularly, hyperbolic plasmons with hyperbolic q-space dispersion are\npredicted to exist in BP films, where highly directional propagating polaritons\nwith divergent densities of states are hosted. Combined with a tunable\nelectronic structure, such natural hyperbolic surfaces may enable a series of\nexotic applications in nanophotonics. In this review, the anisotropic optical\nproperties and plasmons (especially hyperbolic plasmons) of BP are discussed.\nIn addition, other possible 2D material candidates (especially anisotropic\nlayered semimetals) for hyperbolic plasmons are examined. This review may\nstimulate further research interest in anisotropic 2D materials and fully\nunleash their potential in flatland photonics.",
        "positive": "Higher-order topological corner and bond-localized modes in magnonic\n  insulators: We theoretically investigate a two-dimensional decorated honeycomb lattice\nframework to realize a second-order topological magnon insulator (SOTMI) phase\nfeaturing distinct corner-localized modes. Our study emphasizes the pivotal\nrole of spin-magnon mapping in characterizing bosonic topological properties,\nwhich exhibit differences from their fermionic counterparts. We employ a\nsymmetry indicator topological invariant to identify and characterize this\nSOTMI phase, particularly for systems respecting time-reversal and ${\\sf{C}}_6$\nrotational symmetry. Using a spin model defined on a honeycomb lattice\ngeometry, we demonstrate that introducing ``\\textit{kekul\\'e}'' type\ndistortions yields a topological phase. In contrast, ``\\textit{anti-kekul\\'e}''\ndistortions result in a non-topological magnonic phase. The presence of\nkekul\\'e distortions manifests in two distinct topologically protected bosonic\ncorner modes - an \\textit{intrinsic} and a \\textit{pseudo}, based on the\nspecific edge terminations. On the other hand, anti-kekul\\'e distortions give\nrise to \\SW{\\textit{Tamm/Shockley}} type bond-localized boundary modes, which\nare non-topological and reliant on particular edge termination. We further\ninvestigate the effects of random out-of-plane exchange anisotropy disorder on\nthe robustness of these bosonic corner modes. The distinction between SOTMIs\nand their fermionic counterparts arises due to the system-specific magnonic\nonsite energies, a crucial feature often overlooked in prior literature. Our\nstudy unveils exciting prospects for engineering higher-order topological\nphases in magnon systems and enhances our understanding of their unique\nbehavior within decorated honeycomb lattices."
    },
    {
        "anchor": "Asymmetry of the excess finite-frequency noise: We consider finite frequency noise in a mesoscopic system with arbitrary\ninteractions, connected to many terminals kept at finite electrochemical\npotentials. We show that the excess noise, obtained by subtracting the noise at\nzero voltage from that at finite voltage, can be asymmetric with respect to\npositive/negative frequencies if the system is non-linear. This explains a\nrecent experimental observation in Josephson junctions as well as strong\nasymmetry obtained in typical non-linear and strongly correlated systems\ndescribed by the Luttinger liquid (LL): edge states in the fractional quantum\nHall effect, quantum wires and carbon nanotubes. Another important problem\nwhere the LL model applies is that of a coherent conductor embedded in an ohmic\nenvironment.",
        "positive": "Interrupted orbital motion in density-wave systems: In conventional metals, electronic transport in a magnetic field is\ncharacterized by the motion of electrons along orbits on the Fermi surface,\nwhich usually causes an increase in the resistivity through averaging over\nvelocities. Here we show that large deviations from this behavior can arise in\ndensity-wave systems close to their ordering temperature. Specifically,\nenhanced scattering off collective fluctuations can lead to a change of\ndirection of the orbital motion on reconstructed pockets. In weak magnetic\nfields, this leads to linear magnetoconductivity, the sign of which depends on\nthe electric-field direction. At a critical magnetic field, the conductivity\ncrosses zero for certain directions, signifying a thermodynamic instability of\nthe density-wave state."
    },
    {
        "anchor": "Coexistence of spin-1 fermion and Dirac fermion on the triangular kagome\n  lattice: Quasiparticle excitations beyond Dirac-Weyl-Majorana classification can\nappear in lattice systems due to the less symmetry constraint compared with\nPoincar\\'e symmetry in high energy physics. In particular, fermions with an\ninteger spin can appear in a variety of lattices. Here, we show that\ntwo-dimensional spin-1 fermion may coexist with Dirac fermions in the\ntriangular kagome lattice (TKL). We derive a four-band effective model that\nhosts both types of fermions. The effective model can be used to study the\ninterplay between spin-1 and spin-1/2 fermions. As an example, using this model\nwe show that spin-nonconserving Klein tunneling can occur in the TKL, which has\nthe transmission coefficient $T=1$ for normal incidence. Our findings pave a\nway to the study of the interaction and interplay between different types of\nfermions in lattice systems.",
        "positive": "Dirac fermions on a disclinated flexible surface: A self-consisting gauge-theory approach to describe Dirac fermions on\nflexible surfaces with a disclination is formulated. The elastic surfaces are\nconsidered as embeddings into R^3 and a disclination is incorporated through a\ntopologically nontrivial gauge field of the local SO(3) group which generates\nthe metric with conical singularity. A smoothing of the conical singularity on\nflexible surfaces is naturally accounted for by regarding the upper half of\ntwo-sheet hyperboloid as an elasticity-induced embedding. The availability of\nthe zero-mode solution to the Dirac equation is analyzed."
    },
    {
        "anchor": "Entropic Spectral Broadening in Carbon Nanotube Resonators: We simulated the behavior of suspended carbon-nanotube (CNT) resonators over\na broad range of temperatures to address the unexplained spectral broadening\nand frequency shifts seen in experiments. We find that thermal fluctuations\ninduce strong coupling between resonance modes. This effect leads to spectral\nfluctuations which readily account for the experimentally observed quality\nfactors $Q\\sim100$ at $300\\ K$. Using a mean field approach to describe\nentropic fluctuations we analytically calculate $Q$ and frequency shifts in\ntensioned and buckled CNTs and find excellent agreement with simulations.",
        "positive": "Multifractality of wavefunctions at the quantum Hall transition\n  revisited: We investigate numerically the statistics of wavefunction amplitudes\n$\\psi({\\bf r})$ at the integer quantum Hall transition. It is demonstrated that\nin the limit of a large system size the distribution function of $|\\psi|^2$ is\nlog-normal, so that the multifractal spectrum $f(\\alpha)$ is exactly parabolic.\nOur findings lend strong support to a recent conjecture for a critical theory\nof the quantum Hall transition."
    },
    {
        "anchor": "Topologically Protected Edge States in Triangular Lattices: We describe the possibility for topologically robust edge states existing on\ninterfaces of triangular lattices which are supported by rotational symmetries\nthat are sensitive to boundary conditions. Such states are trivial from the\nperspective of Berry curvature, but result instead from an interplay between\ncrystalline symmetries and finite boundary effects. Regardless, we show such\nstates are in a distinct topological phase, provided the gauge-dependent\nsymmetries are maintained. Such a model describes a number of recent bosonic\nexperimental demonstrations on triangular lattices, the physics for which has\nthus far eluded explanation.",
        "positive": "Meissner effect in the layered Kane-Mele model with Hubbard interaction: We investigate the magnetic response in the quantum spin Hall phase of the\nlayered Kane-Mele model with Hubbard interaction, and argue a condition to\nobtain the Meissner effect. The effect of Rashba spin orbit coupling is also\ndiscussed."
    },
    {
        "anchor": "Tunneling Current Measurement Scheme to Detect Majorana Zero Mode\n  Induced Crossed Andreev Reflection: We propose a scheme to detect the Majorana-zero-mode-induced crossed Andreev\nreflection by measuring tunneling current directly. In this scheme a metallic\nring structure is utilized to separate electron and hole signals. Since\ntunneling electrons and holes have different propagating wave vectors, the\nconditions for them to be constructively coherent in the ring differ. We find\nthat when the magnetic flux threading the ring varies, it is possible to\nobserve adjacent positive and negative current peaks of almost equal\namplitudes.",
        "positive": "Quantum oscillations and electronic structures in large Chern number\n  semimetal RhSn: We report the magnetoresistance, Hall effect, de Haas-van Alphen (dHvA)\noscillations and the electronic structures of single crystal RhSn, which is a\ntypical material of CoSi family holding a large Chern number. The large\nunsaturated magnetoresistance is observed with B//[001]. The Hall resistivity\ncurve indicates that RhSn is a multi-band system with high mobility. Evident\nquantum oscillations have been observed, from which the light effective masses\nare extracted. Ten fundamental frequencies are extracted after the fast Fourier\ntransform analysis of the dHvA oscillations with B//[001] configuration. The\ntwo low frequencies F$_1$ and F$_2$ do not change obviously and the two high\nfrequencies F$_9$ and F$_{10}$ evolve into four when B rotates from B//[001] to\nB//[110], which is consistent with the band structure in the first-principles\ncalculations with spin-orbit coupling (SOC). The extracted Berry phases of the\nrelative pockets show a good agreement with the Chern number $\\pm4$ (with SOC)\nin the first-principles calculations. Above all, our studies indicate that RhSn\nis an ideal platform to study the unconventional chiral fermions and the\nsurface states."
    },
    {
        "anchor": "Gate-Tunable Topological Flat Bands in Trilayer Graphene-Boron Nitride\n  Moir\u00e9 Superlattices: We investigate the electronic structure of the flat bands induced by moir\\'e\nsuperlattices and electric fields in nearly aligned ABC trilayer graphene-boron\nnitride interfaces where Coulomb effects can lead to correlated gapped phases.\nOur calculations indicate that valley-spin resolved isolated superlattice flat\nbands that carry a finite Chern number $C = 3$ proportional to layer number can\nappear near charge neutrality for appropriate perpendicular electric fields and\ntwist angles. When the degeneracy of the bands is lifted by Coulomb\ninteractions these topological bands can lead to anomalous quantum Hall phases\nthat embody orbital and spin magnetism. Narrow bandwidths of $\\sim10$ meV\nachievable for a continuous range of twist angles $\\theta \\lesssim 0.6^{\\circ}$\nwith moderate interlayer potential differences of $\\sim$50 meV make the TLG/BN\nsystems a promising platform for the study of electric-field tunable Coulomb\ninteraction driven spontaneous Hall phases.",
        "positive": "Universal signatures of Dirac fermions in entanglement and charge\n  fluctuations: We investigate the entanglement entropy (EE) and charge fluctuations in\nmodels where the low energy physics is governed by massless Dirac fermions. We\nfocus on the response to flux insertion which, for the EE, is widely assumed to\nbe universal, \\emph{i.e.}, independent of the microscopic details. We provide\nan analytical derivation of the EE and charge fluctuations for the seminal\nexample of graphene, using the dimensional reduction of its tight-binding model\nto the one-dimensional Su-Schrieffer-Heeger model. Our asymptotic expression\nfor the EE matches the conformal field theory prediction. We show that the\ncharge variance has the same asymptotic behavior, up to a constant prefactor.\nTo check the validity of universality arguments, we numerically consider\nseveral models, with different geometries and number of Dirac cones, and either\nfor strictly two-dimensional models or for gapless surface mode of\nthree-dimensional topological insulators. We also show that the flux response\ndoes not depend on the entangling surface geometry as long as it encloses the\nflux. Finally we consider the universal corner contributions to the EE. We show\nthat in the presence of corners, the Kitaev-Preskill subtraction scheme\nprovides non-universal, geometry dependent results."
    },
    {
        "anchor": "Microwave-optical coupling via Rydberg excitons in cuprous oxide: We report exciton-mediated coupling between microwave and optical fields in\ncuprous oxide (Cu$_2$O) at low temperatures. Rydberg excitonic states with\nprincipal quantum number up to $n=12$ were observed at 4~K using both\none-photon (absorption) and two-photon (second harmonic generation)\nspectroscopy. Near resonance with an excitonic state, the addition of a\nmicrowave field significantly changed the absorption lineshape, and added\nsidebands at the microwave frequency to the coherent second harmonic. Both\neffects showed a complex dependence on $n$ and angular momentum, $l$. All of\nthese features are in semi-quantitative agreement with a model based on\nintraband electric dipole transitions between Rydberg exciton states. With a\nsimple microwave antenna we already reach a regime where the microwave coupling\n(Rabi frequency) is comparable to the nonradiatively broadened linewidth of the\nRydberg excitons. The results provide a new way to manipulate excitonic states,\nand open up the possibility of a cryogenic microwave to optical transducer\nbased on Rydberg excitons.",
        "positive": "Electrical manipulation of valley-qubit and valley geometric phase in\n  lateral monolayer heterostructures: We explore a solid state qubit defined on valley isospin of an electron\nconfined in a gate-defined quantum dot created in an area of monolayer\nMoS$_2$/WS$_2$ lateral junction, where a steep dipolar potential emerges. We\nshow that the junction oriented along an armchair direction can induce\nintervalley transitions of the electron confined in the neighboring quantum dot\nwhen the (gate-controllable) overlapping with the junction is significant and\npumping frequency tuned. The pumping scheme that induces transitions is\nall-electrical: obtained by applying oscillating voltages to control gates and\nthus enables for scalable qubit architectures. We also report another\npossibility of valley-qubit manipulation by accumulating non-Abelian valley\nBerry phase. To model nanodevice we solve the time-dependent\nSchr\\\"odinger-Poisson equations in a tight-binding approach and obtain exact\ntime-evolution of the valley-qubit system."
    },
    {
        "anchor": "Conductance of Interacting Quasi-One-Dimensional Electron Gas with a\n  Scatterer: We calculate the conductance of a quantum wire with two occupied subbands in\na presence of a barrier taking into account the interaction between electrons.\nWe extend the renormalization-group equation for the scattering matrix of the\nbarrier to the case of intersubband interactions, find its fixed points, and\ninvestigate their stability. Depending on the interaction parameters, the\nconductance may be equal to 0, $e^2/h$, or $2e^2/h$ per spin projection. In\nsome parameter ranges, two stable fixed points may coexist, so the ultimate\nconductance depends on the properties of the bare barrier. For spinful\nelectrons, the conductance of the wire may nonmonotonically depend on the Fermi\nlevel and temperature.",
        "positive": "Hyperfine interaction for holes in quantum dots: k.p model: We formulate the multi-band kp theory of hyperfine interactions for\nsemiconductor nanostructures in the envelope function approximation. We apply\nthis theoretical description to the fluctuations of the longitudinal and\ntransverse Overhauser field experienced by a hole for a range of InGaAs quantum\ndots of various compositions and geometries. We find that for a wide range of\nvalues of $d$-shell admixture to atomic states forming the top of the valence\nband, the transverse Overhauser field caused by this admixture is of the same\norder of magnitude as the longitudinal one, and band mixing adds only a minor\ncorrection to this result. In consequence, the kp results are well reproduced\nby a simple box model with the effective number of ions determined by the wave\nfunction participation number, as long as the hole is confined in the\ncompositionally uniform volume of the dot, which holds in a wide range of\nparameters, excluding very flat dots."
    },
    {
        "anchor": "Influence of device geometry on tunneling in \u03bd=5/2 quantum Hall liquid: Two recent experiments [I. P. Radu et al., Science 320, 899 (2008) and X. Lin\net al., Phys. Rev. B 85, 165321 (2012)] measured the temperature and voltage\ndependence of the quasiparticle tunneling through a quantum point contact in\nthe \\nu= 5/2 quantum Hall liquid. The results led to conflicting conclusions\nabout the nature of the quantum Hall state. In this paper, we show that the\nconflict can be resolved by recognizing different geometries of the devices in\nthe experiments. We argue that in some of those geometries there is significant\nunscreened electrostatic interaction between the segments of the quantum Hall\nedge on the opposite sides of the point contact. Coulomb interaction affects\nthe tunneling current. We compare experimental results with theoretical\npredictions for the Pfaffian, SU(2)_2, 331 and K=8 states and their\nparticle-hole conjugates. After Coulomb corrections are taken into account,\nmeasurements in all geometries agree with the spin-polarized and\nspin-unpolarized Halperin 331 states.",
        "positive": "Magnetoresistance from broken spin helicity: The propensity of some materials and multilayers to have a magnetic field\ndependent resistance, called magnetoresistance, has found commercial\napplications such as giant magnetoresistance harddisk read heads. But\nmagnetoresistance can also be a powerful probe of electronic and magnetic\ninteractions in matter. For example, magnetoresistance can be used to analyze\nmultiband conductivity, conduction inhomogeneity, localized magnetic moments,\nand (fractional) Landau level structure. For materials with strong spin-orbit\ninteraction, magnetoresistance can be used as a probe for weak antilocalization\nor a nontrivial Berry phase, such as in topological insulator surface states.\nFor the three dimensional topological insulators a large and linear\nmagnetoresistance is often used as indication for underlying non-trivial\ntopology, although the origin of this effect has not yet been established.\nHere, we observe a large magnetoresistance in the conducting bulk state of\nBi$_2$Te$_3$. We show that this type of large magnetoresistance is due to the\ncompetition between helical spin-momentum locking (i.e. spin rotates with\nmomentum direction) and the unidirectional spin alignment by an applied\nmagnetic field. Warping effects are found to provide the (quasi) linear\ndependence on magnetic field. We provide a quantitative model for the helicity\nbreaking induced magnetoresistance that can be applied to a vast range of\nmaterials, surfaces or interfaces with weak to strong spin-orbit interactions,\nsuch as the contemporary oxide interfaces, bulk Rashba systems, and topological\ninsulator surface states."
    },
    {
        "anchor": "Spin-polarized tunneling current through a thin film of topological\n  insulator in a parallel magnetic field: We calculate the tunneling conductance \\sigma between the surface states on\nthe opposite sides of the ultra-thin film of a topological insulator in a\nparallel magnetic field B_y. The parallel magnetic produces a relative shift of\nthe in-plane momenta of the two surfaces states. An overlap between the shifted\nFermi circles and their spin structure define an unusual dependence of the\ntunneling conductance \\sigma(B_y) on the magnetic field. Because the spin of\nthe electronic surface states in topological insulators is locked with\nmomentum, the spin-polarization of the tunneling current can be controlled by\nmagnetic field B_y.",
        "positive": "Classical properties of low-dimensional conductors: Giant capacitance\n  and non-Ohmic potential drop: Electrical field arising around an inhomogeneous conductor when an electrical\ncurrent passes through it is not screened, as distinct from 3D conductors, in\nlow-dimensional conductors. As a result, the electrical field depends on the\nglobal distribution of the conductivity sigma(x) rather than on the local value\nof it, inhomogeneities of sigma(x) produce giant capacitances C(omega) that\nshow frequency dependence at relatively low omega, and electrical fields\ndevelop in vast regions around the inhomogeneities of sigma(x). A theory of\nthese phenomena is presented for 2D conductors."
    },
    {
        "anchor": "Electronic structure of GaSb/AlGaSb quantum dots formed by filling\n  droplet-etched nanoholes: Epitaxially-grown semiconductor quantum dots (QDs) provide an attractive\nplatform for the development of deterministic sources of high-quality quantum\nstates of light. Such non-classical light sources are essential for quantum\ninformation processing and quantum communication. QDs emitting in the telecom\nwavelengths are especially important for ensuring compatibility with optical\nfiber systems required to implement quantum communication networks. To this\nend, GaSb QDs fabricated by filling local-droplet etched nanoholes are emerging\nas a viable approach, yet the electronic properties of such nanostructures have\nnot been studied in detail. In this article, an insight into the electronic\nstructure and carrier dynamics in GaSb/AlGaSb QDs is provided through a\nsystematic experimental analysis of their temperature-dependent\nphotoluminescence behavior. A steady-state rate equation model is used to\nreveal the relevant energy barriers for thermally activated carrier capture and\nescape processes. Furthermore, results of detailed theoretical simulations of\nquantum-confined energy states using the multi-band k.p model and the effective\nmass method are presented. The purpose of the simulations is to reveal the\ndirect and indirect energy states, carrier wavefunctions, and allowed optical\ntransitions for GaSb QDs with different physical dimensions.",
        "positive": "Transport in quantum wells in the presence of interface roughness: The effective Hamiltonian for two dimensional quantum wells with rough\ninterfaces is formally derived. Two new terms are generated. The first term is\nidentified to the local energy level fluctuations, which was introduced\nphenomenologically in the literature for interface roughness scattering but is\nnow shown to be valid only for an infinite potential well or Hamiltonians with\none single length scale. The other term is shown to modulate the wavefunction\nand cause fluctuations in the charge density. This will further reduce the\nelectron mobility to the magnitude that is close to the experimental result."
    },
    {
        "anchor": "Finite-temperature Bell test for quasiparticle entanglement in the Fermi\n  sea: We demonstrate that the Bell test cannot be realized at finite temperatures\nin the vast majority of electronic setups proposed previously for quantum\nentanglement generation. This fundamental difficulty is shown to originate in a\nfinite probability of quasiparticle emission from Fermi-sea detectors. In order\nto overcome the feedback problem, we suggest a detection strategy, which takes\nadvantage of a resonant coupling to the quasiparticle drains. Unlike other\nproposals, the designed Bell test provides a possibility to determine the\ncritical temperature for entanglement production in the solid state.",
        "positive": "Improved placement precision of implanted donor spin qubits in silicon\n  using molecule ions: Donor spins in silicon-28 ($^{28}$Si) are among the most performant qubits in\nthe solid state, offering record coherence times and gate fidelities above 99%.\nDonor spin qubits can be fabricated using the semiconductor-industry compatible\nmethod of deterministic ion implantation. Here we show that the precision of\nthis fabrication method can be boosted by implanting molecule ions instead of\nsingle atoms. The bystander ions, co-implanted with the dopant of interest,\ncarry additional kinetic energy and thus increase the detection confidence of\ndeterministic donor implantation employing single ion detectors to signal the\ninduced electron-hole pairs. This allows the placement uncertainty of donor\nqubits to be minimised without compromising on detection confidence. We\ninvestigate the suitability of phosphorus difluoride (PF$_2^+$) molecule ions\nto produce high quality P donor qubits. Since $^{19}$F nuclei have a spin of $I\n= 1/2$, it is imperative to ensure that they do not hyperfine couple to P donor\nelectrons as they would cause decoherence by adding magnetic noise. Using\nsecondary ion mass spectrometry, we confirm that F diffuses away from the\nactive region of qubit devices while the P donors remain close to their\noriginal location during a donor activation anneal. PF$_2$-implanted qubit\ndevices were then fabricated and electron spin resonance (ESR) measurements\nwere performed on the P donor electron. A pure dephasing time of $T_2^* = 20.5\n\\pm 0.5$ $\\mu$s and a coherence time of $T_2^{Hahn} = 424 \\pm 5$ $\\mu$s were\nextracted for the P donor electron-values comparable to those found in previous\nP-implanted qubit devices. Closer investigation of the P donor ESR spectrum\nrevealed that no $^{19}$F nuclear spins were found in the vicinity of the P\ndonor. Molecule ions therefore show great promise for producing high-precision\ndeterministically-implanted arrays of long-lived donor spin qubits."
    },
    {
        "anchor": "Anomalous circular phonon dichroism in transition metal dichalcogenides: A magnetic field can generally induce circular phonon dichroism based on the\nformation of Landau levels of electrons. Here, we study the\nmagnetization-induced circular phonon dichroism in transition metal\ndichalcogenides, without forming Landau levels. We find that, instead of the\nconventional deformation potential coupling, pseudogauge-type electron-phonon\ncoupling plays an essential role in the emergence of the phenomenon. As a\nconcrete example, a large dichroism signal is obtained in monolayer MoTe2 on a\nEuO substrate, even without considering Rashba spin-orbit coupling. Due to the\ntwo-dimensional spin-valley-coupled band structure, MoTe2 shows a reciprocal\nand nonreciprocal absorption of circularly polarized acoustic phonons upon\nreversing the direction of phonon propagation and magnetization, respectively.\nBy varying the gate voltage, a tunable circular phonon dichroism can be\nrealized, which paves a way toward different physics and applications of\ntwo-dimensional acoustoelectronics.",
        "positive": "Quantum pumping and rectification effects in Aharonov-Bohm-Casher\n  ring-dot systems: We study the time-dependent transport of charge and spin through a\nring-shaped region sequentially coupled to a weakly interacting quantum dot in\nthe presence of an Aharonov-Bohm flux and spin-orbit interaction. The\ntime-dependent modulation of the spin-orbit interaction, or of the\ncorresponding Aharonov-Casher flux, together with the modulation of the\ndot-level induces an electrically pumped spin current even in absence of a\ncharge current. The results beyond the adiabatic regime show that an additional\nrectification current proportional to \\cos(\\phi), being \\phi the relative phase\nbetween the time varying parameters, is generated. We discuss the relevance of\nsuch term in connection with recent experiments on out-of-equilibrium quantum\ndots."
    },
    {
        "anchor": "Spin relaxation in $n$-type (111) GaAs quantum wells: We investigate the spin relaxation limited by the D'yakonov-Perel' mechanism\nin $n$-type (111) GaAs quantum wells, by means of the kinetic spin Bloch\nequation approach. In (111) GaAs quantum wells, the in-plane effective magnetic\nfield from the D'yakonov-Perel' term can be suppressed to zero on a special\nmomentum circle under the proper gate voltage, by the cancellation between the\nDresselhaus and Rashba spin-orbit coupling terms. When the spin-polarized\nelectrons mainly distribute around this special circle, the in-plane\ninhomogeneous broadening is small and the spin relaxation can be suppressed,\nespecially for that along the growth direction of quantum well. This\ncancellation effect may cause a peak (the cancellation peak) in the density or\ntemperature dependence of the spin relaxation time. In the density\n(temperature) dependence, the interplay between the cancellation peak and the\nordinary density (Coulomb) peak leads to rich features of the density\n(temperature) dependence of the spin relaxation time. The effect of impurities,\nwith its different weights on the cancellation peak and the Coulomb peak in the\ntemperature dependence of the spin relaxation, is revealed. We also show the\nanisotropy of the spin relaxation with respect to the spin-polarization\ndirection.",
        "positive": "Parity-dependent shot noise and spin-flip relaxation process in a hybrid\n  superconductor-nanowire quantum dot: We report shot noise measurements for a quantum dot formed in an InAs\nnanowire suspended between superconducting electrodes. We find a clear\nalternation for the shot noise value in the Coulomb blockade regime between\neven and odd electron occupation in the dot, indicating that super-Poissonian\n(Poissonian) shot noise with the Fano factor reaching around 2 (1) occurs for\neven (odd) parity. With increasing magnetic field, the parity effect disappears\nand all the regimes show the Fano factor of around 1. The whole observation in\nour experiments quantitatively agrees with simulation obtained from\nfull-counting statistics of cotunneling including spin-flip relaxation process,\nwhich corresponds to modelling electron motion in a quantum dot with strong\nspin-orbit interaction."
    },
    {
        "anchor": "Quantum Effects in the Nonlinear Response of Graphene Plasmons: The ability of graphene to support long-lived, electrically tunable plasmons\nthat interact strongly with light, combined with its highly nonlinear optical\nresponse, has generated great expectations for application of the\natomically-thin material to nanophotonic devices. These expectations are mainly\nreinforced by classical analyses performed using the response derived from\nextended graphene, neglecting finite-size and nonlocal effects that become\nimportant when the carbon layer is structured on the nanometer scale in actual\ndevice designs. Here we show that finite-size effects produce large\ncontributions that increase the nonlinear response of nanostructured graphene\nto significantly higher levels than those predicted by classical theories. We\nbase our analysis on a quantum-mechanical description of graphene using\ntight-binding electronic states combined with the random-phase approximation.\nWhile classical and quantum descriptions agree well for the linear response\nwhen either the plasmon energy is below the Fermi energy or the size of the\nstructure exceeds a few tens of nanometers, this is not always the case for the\nnonlinear response, and in particular, third-order Kerr-type nonlinearities are\ngenerally underestimated by the classical theory. Our results reveal the\ncomplex quantum nature of the optical response in nanostructured graphene,\nwhile further supporting the exceptional potential of this material for\nnonlinear nanophotonic devices.",
        "positive": "Dynamic local strain in graphene generated by surface acoustic waves: We experimentally demonstrate that the Raman active optical phonon modes of\nsingle layer graphene can be modulated by the dynamic local strain created by\nsurface acoustic waves (SAWs). In particular, the dynamic strain field of the\nSAW is shown to induce a Raman scattering intensity variation as large as 15%\nand a phonon frequency shift of up to 10 cm$^{-1}$ for the G band, for\ninstance, for an effective hydrostatic strain of 0.24% generated in a single\nlayer graphene atop a LiNbO$_{3}$ piezoelectric substrate with a SAW resonator\noperating at a frequency of $ \\sim $ 400 MHz. Thus, we demonstrate that SAWs\nare powerful tools to modulate the optical and vibrational properties of\nsupported graphene by means of the high-frequency localized deformations\ntailored by the acoustic transducers, which can also be extended to other 2D\nsystems."
    },
    {
        "anchor": "Ohmic contacts to 2D semiconductors through van der Waals bonding: High contact resistances have blocked the progress of devices based on MX2 (M\n= Mo,W; X = S,Se,Te) 2D semiconductors. Interface states formed at MX2/metal\ncontacts pin the Fermi level, leading to sizable Schottky barriers for p-type\ncontacts in particular. We show that (i) one can remove the interface states by\ncovering the metal by a 2D layer, which is van der Waals-bonded to the MX2\nlayer, and (ii) one can choose the buffer layer such, that it yields a p-type\ncontact with a zero Schottky barrier height. We identify possible buffer layers\nsuch as graphene, a monolayer of h-BN, or an oxide layer with a high electron\naffinity, such as MoO3. The most elegant solution is a metallic M'X'2 layer\nwith a high work function. A NbS2 monolayer adsorbed on a metal yields a high\nwork function contact, irrespective of the metal, which gives a barrierless\ncontact to all MX2 layers.",
        "positive": "Pauli spin-blockade in an InAs nanowire double quantum dot: We measure transport at finite bias through a double quantum dot formed by\ntop-gates in an InAs nanowire. Pauli spin-bockade is confirmed with several\nelectrons in the dot. This is expected due to the small exchange interactions\nin InAs and the large singlet-triplet splitting, which can be measured and\ntuned by a gate voltage."
    },
    {
        "anchor": "Gravitational Anomalies and Thermal Hall effect in Topological\n  Insulators: It has been suggested that a temperature gradient will induce a Leduc-Righi,\nor thermal Hall, current in the Majorana quasiparticles localized on the\nsurface of class DIII topological insulators, and that the magnitude of this\ncurrent can be related {\\it via} an Einstein argument to a Hall-like energy\nflux induced by gravity. We critically examine this idea, and argue that the\ngravitational Hall effect is more complicated than its familiar analogue. A\nconventional Hall current is generated by a {\\it uniform} electric field, but\ncomputing the flux from the gravitational Chern-Simons functional shows that\ngravitational field {\\it gradients} - i.e. tidal forces - are needed to induce\na energy-momentum flow. We relate the surface energy-momentum flux to a\ndomain-wall gravitational anomaly {\\it via} the Callan-Harvey inflow mechanism.\nWe stress that the gauge invariance of the combined bulk-plus-boundary theory\nensures that the current in the domain wall always experiences a \"covariant\"\nrather than \"consistent\" anomaly. We use this observation to confirm that the\ntidally induced energy-momentum current exactly accounts for the covariant\ngravitational anomaly in $(1+1)$ dimensional domain-wall fermions. The same\nanomaly arises whether we write the Chern-Simons functional in terms of the\nChristofflel symbol or in terms of the the spin connection.",
        "positive": "Ferromagnetic resonance assisted optomechanical magnetometer: The resonant enhancement of mechanical and optical interaction in\noptomechanical cavities enables their use as extremely sensitive displacement\nand force detectors. In this work we demonstrate a hybrid magnetometer that\nexploits the coupling between the resonant excitation of spin waves in a\nferromagnetic insulator and the resonant excitation of the breathing mechanical\nmodes of a glass microsphere deposited on top. The interaction is mediated by\nmagnetostriction in the ferromagnetic material and the consequent mechanical\ndriving of the microsphere. The magnetometer response thus relies on the\nspectral overlap between the ferromagnetic resonance and the mechanical modes\nof the sphere, leading to a peak sensitivity better than 900 pT Hz$^{-1/2}$ at\n206 MHz when the overlap is maximized. By externally tuning the ferromagnetic\nresonance frequency with a static magnetic field we demonstrate sensitivity\nvalues at resonance around a few nT Hz$^{-1/2}$ up to the GHz range. Our\nresults show that our hybrid system can be used to build high-speed sensor of\noscillating magnetic fields."
    },
    {
        "anchor": "Magnetoelasticity of $\\mathrm{Co_{25}}\\mathrm{Fe_{75}}$ thin films: We investigate the magnetoelastic properties of\n$\\mathrm{Co_{25}}\\mathrm{Fe_{75}}$ and $\\mathrm{Co_{10}}\\mathrm{Fe_{90}}$ thin\nfilms by measuring the mechanical properties of a doubly clamped string\nresonator covered with multi-layer stacks containing these films. For the\nmagnetostrictive constants we find\n$\\lambda_{\\mathrm{Co_{25}}\\mathrm{Fe_{75}}}=(-20.68\\pm0.25)\\times10^{-6}$ and\n$\\lambda_{\\mathrm{Co_{10}}\\mathrm{Fe_{90}}}=(-9.80\\pm0.12)\\times10^{-6}$ at\nroom temperature. In stark contrast to the positive magnetostriction previously\nfound in bulk CoFe crystals. $\\mathrm{Co_{25}}\\mathrm{Fe_{75}}$ thin films\nunite low damping and sizable magnetostriction and are thus a prime candidate\nfor micromechanical magnonic applications, such as sensors and hybrid\nphonon-magnon systems.",
        "positive": "Gigantic enhancement of spin Seebeck effect by phonon drag: We investigate both theoretically and experimentally a gigantic enhancement\nof the spin Seebeck effect in a prototypical magnet LaY$_2$Fe$_5$O$_{12}$ at\nlow temperatures. Our theoretical analysis sheds light on the important role of\nphonons; the spin Seebeck effect is enormously enhanced by nonequilibrium\nphonons that drag the low-lying spin excitations. We further argue that this\nscenario gives a clue to understand the observation of the spin Seebeck effect\nthat is unaccompanied by a global spin current, and predict that the substrate\ncondition affects the observed signal."
    },
    {
        "anchor": "Thermodynamics and linear response of a Bose-Einstein condensate of\n  microcavity polaritons: In this work we derive a theory of polariton condensation based on the theory\nof interacting Bose particles. In particular, we describe self-consistently the\nlinear exciton-photon coupling and the exciton-nonlinearities, by generalizing\nthe Hartree-Fock-Popov description of BEC to the case of two coupled Bose\nfields at thermal equilibrium. In this way, we compute the density-dependent\none-particle spectrum, the energy occupations and the phase diagram. The\nresults quantitatively agree with the existing experimental findings. We then\npresent the equations for the linear response of a polariton condensate and we\npredict the spectral response of the system to external optical or mechanical\nperturbations.",
        "positive": "Tunnel Barrier to Spin Filter: Electronic Transport Characteristics of\n  Transition Metal Atom Encapsulated in Smallest Cadmium Telluride Cage: We report first principles theory-based comparative electronic transport\nstudies performed for an atomic chain of Au, bare Cd9Te9 cage-like cluster and\nsingle transition metal (TM) (Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ru, Rh, Pd)\natom encapsulated within the Cd9Te9 using Au(111) as electrodes. The bare\ncluster is semiconducting and acts as a tunnel barrier up to a particular\napplied bias and beyond that, the device has a linear current-voltage\nrelationship. Several TM (Ti, V, Cr, Mn, Fe) encapsulated in the cage show\nhalf-metallic behavior and spin filtering effect in the I-V characteristics of\nthe device. A detailed qualitative and quantitative analysis of I-V\ncharacteristics for metallic, semiconducting, and half-metallic nanostructures\nhas been carried out."
    },
    {
        "anchor": "High-fidelity readout and control of a nuclear spin qubit in silicon: A single nuclear spin holds the promise of being a long-lived quantum bit or\nquantum memory, with the high fidelities required for fault-tolerant quantum\ncomputing. We show here that such promise could be fulfilled by a single\nphosphorus (31P) nuclear spin in a silicon nanostructure. By integrating\nsingle-shot readout of the electron spin with on-chip electron spin resonance,\nwe demonstrate the quantum non-demolition, electrical single-shot readout of\nthe nuclear spin, with readout fidelity better than 99.8% - the highest for any\nsolid-state qubit. The single nuclear spin is then operated as a qubit by\napplying coherent radiofrequency (RF) pulses. For an ionized 31P donor we find\na nuclear spin coherence time of 60 ms and a 1-qubit gate control fidelity\nexceeding 98%. These results demonstrate that the dominant technology of modern\nelectronics can be adapted to host a complete electrical measurement and\ncontrol platform for nuclear spin-based quantum information processing.",
        "positive": "Modelling Two-Roton Bound State Formation in Fractional Quantum Hall\n  System: Composite Fermion approach using extensive and parallalized numerical\nanalysis has recently established a two-roton bound state as the lowest energy\nlong wavelength neutral excitation of FQHE for finite particle (N~30) system.\nBy focussing on the \"oriented dipole\" character of magneto roton, we model the\ntwo roton problem and solve it variationally (analytically) to find a two-roton\nbound state with binding energy which is in good agreement with the composite\nfermion numerical results."
    },
    {
        "anchor": "Exotic attractors of the non-equilibrium Rabi-Hubbard model: We explore the phase diagram of the dissipative Rabi-Hubbard model, as could\nbe realized by a Raman-pumping scheme applied to a coupled cavity array. There\nexist various exotic attractors, including ferroelectric, antiferroelectric,\nand inccomensurate fixed points, as well as regions of persistent oscillations.\nMany of these features can be understood analytically by truncating to the two\nlowest lying states of the Rabi model on each site. We also show that these\nfeatures survive beyond mean-field, using Matrix Product Operator simulations.",
        "positive": "Dephasing of a superconducting qubit induced by photon noise: We have studied the dephasing of a superconducting flux-qubit coupled to a\nDC-SQUID based oscillator. By varying the bias conditions of both circuits we\nwere able to tune their effective coupling strength. This allowed us to measure\nthe effect of such a controllable and well-characterized environment on the\nqubit coherence. We can quantitatively account for our data with a simple model\nin which thermal fluctuations of the photon number in the oscillator are the\nlimiting factor. In particular, we observe a strong reduction of the dephasing\nrate whenever the coupling is tuned to zero. At the optimal point we find a\nlarge spin-echo decay time of $4 \\mu s$."
    },
    {
        "anchor": "Numerical study of parametric pumping current in mesoscopic systems in\n  the presence of magnetic field: We numerically study the parametric pumped current when magnetic field is\napplied both in the adiabatic and non-adiabatic regimes. In particular, we\ninvestigate the nature of pumped current for systems with resonance as well as\nanti-resonance. It is found that in the adiabatic regime, the pumped current\nchanges sign across the sharp resonance with long lifetime while the\nnon-adiabatic pumped current at finite frequency does not. When the lifetime of\nresonant level is short, the behaviors of adiabatic and non-adiabatic pumped\ncurrent are similar with sign changes. Our results show that at the energy\nwhere complete transmission occurs the adiabatic pumped current is zero while\nnon-adiabatic pumped current is non-zero. Different from the resonant case,\nboth adiabatic and non-adiabatic pumped current are zero at anti-resonance with\ncomplete reflection. We also investigate the pumped current when the other\nsystem parameters such as magnetic field, pumped frequency, and pumping\npotentials. Interesting behaviors are revealed. Finally, we study the symmetry\nrelation of pumped current for several systems with different spatial symmetry\nupon reversal of magnetic field. Different from the previous theoretical\nprediction, we find that a system with general inversion symmetry can pump out\na finite current in the adiabatic regime. At small magnetic field, the pumped\ncurrent has an approximate relation I(B) \\approx I(-B) both in adiabatic and\nnon-adiabatic regimes.",
        "positive": "Multiband quasiparticle interference in the topological insulator\n  Cu_(x)Bi_(2)Te_(3): We present angle resolved photoemission experiments and scanning tunneling\nspectroscopy results on the doped topological insulator Cu0.2Bi2Te3.\nQuasi-particle interference (QPI) measurements, based on high resolution\nconductance maps of the local density of states show that there are three\ndistinct energy windows for quasi-particle scattering. Using a model\nHamiltonian for this system two new scattering channels are identified: the\nfirst between the surface states and the conduction band and the second between\nconduction band states. We also observe that the real space density modulation\nhas a predominant three-fold symmetry, which rules out a simple, isotropic\nimpurity potential. We obtain agreement between experiment and theory by\nconsidering a modified scattering potential that is consistent with having\nmostly Bi-Te anti-site defects as scatterers."
    },
    {
        "anchor": "Phonon-assisted Photoluminescence from Dark Excitons in Monolayers of\n  Transition Metal Dichalcogenides: The photoluminescence (PL) spectrum of transition metal dichalcogenides\n(TMDs) shows a multitude of emission peaks below the bright exciton line and\nnot all of them have been explained yet. Here, we study the emission traces of\nphonon-assisted recombinations of momentum-dark excitons. To this end, we\ndevelop a microscopic theory describing simultaneous exciton, phonon and photon\ninteraction and including consistent many-particle dephasing. We explain the\ndrastically different PL below the bright exciton in tungsten- and\nmolybdenum-based materials as result of different configurations of bright and\ndark states. In good agreement with experiments, we show that WSe$_2$ exhibits\nclearly visible low-temperature PL signals stemming from the phonon-assisted\nrecombination of momentum-dark excitons.",
        "positive": "Normal metal - superconductor tunnel junction as a Brownian refrigerator: Thermal noise generated by a hot resistor (resistance $R$) can, under proper\nconditions, catalyze heat removal from a cold normal metal (N) in contact with\na superconductor (S) via a tunnel barrier. Such a NIS junction acts as\nMaxwell's demon, rectifying the heat flow. Upon reversal of the temperature\ngradient between the resistor and the junction the heat fluxes are reversed:\nthis presents a regime which is not accessible in an ordinary voltage-biased\nNIS structure. We obtain analytical results for the cooling performance in an\nidealized high impedance environment, and perform numerical calculations for\ngeneral $R$. We conclude by assessing the experimental feasibility of the\nproposed effect."
    },
    {
        "anchor": "Optical Polarization Analogs in Inelastic Free Electron Scattering: Advances in the ability to manipulate free electron phase profiles within the\nelectron microscope have spurred development of quantum-mechanical descriptions\nof electron energy loss (EEL) processes involving transitions between\nphase-shaped transverse states. Here, we elucidate an underlying connection\nbetween two ostensibly distinct optical polarization analogs identified in EEL\nexperiments as manifestations of the same conserved scattering flux. Our work\nintroduces a procedure for probing general tensorial target characteristics\nincluding global mode symmetries and local polarization.",
        "positive": "Growth and Optical Properties Investigation of Pure and Al-doped SnO2\n  Nanostructures by Sol-Gel Method: SnO2 nanoparticles with different percentage of Al (5%, 15%, and25%) were\nsynthesized by sol-gel method. The structure and nature of nanoparticles are\ndetermined by of X-ray diffraction analysis. Also morphology of the samples is\nevaluated by SEM. Moreover, the optical properties of the samples are\ninvestigated with UV-Visible and FT-IR. The XRD patterns are indicated that all\nsamples and incorporation aluminum ions into the SnO2 lattice have tetragonal\nrutile structure. The crystalline size of nanoparticles is decreased with\nincreasing the Al percentage. The SEM results confirmed that the size of\nnanoparticles decreases with increasing the Al percentage. Also, FT-IR and\nUV-Visible results showed that the optical band gap of nanoparticles increases\nwith the increasing the Al percentage. Finally, we have used the EDX analysis\nto study the chemical composition of the products. Pure tin and oxygen have\nbeen observed. The doped samples showed the existence of Al atoms in the\nsamples of the crystal structure of SnO2."
    },
    {
        "anchor": "Graphene single electron transistor as a spin sensor for magnetic\n  adsorbates: We study single electron transport through a graphene quantum dot with\nmagnetic adsorbates. We focus on the relation between the spin order of the\nadsorbates and the linear conductance of the device. The electronic structure\nof the graphene dot with magnetic adsorbates is modeled through numerical\ndiagonalization of a tight-binding model with an exchange potential. We\nconsider several mechanisms by which the adsorbate magnetic state can influence\ntransport in a single electron transistor: by tuning the addition energy, by\nchanging the tunneling rate and, in the case of spin polarized electrodes,\nthrough magnetoresistive effects. Whereas the first mechanism is always\npresent, the others require that the electrode has either an energy or spin\ndependent density of states. We find that graphene dots are optimal systems to\ndetect the spin state of a few magnetic centers.",
        "positive": "The Murphy-Good plot: a better method of analysing field emission data: Measured field electron emission (FE) current-voltage Im(Vm) data are\ntraditionally analysed via Fowler-Nordheim (FN) plots, as ln{Im/(Vm)**2} vs\n1/Vm. These have been used since 1929, because in 1928 FN predicted they would\nbe linear. In the 1950s, a mistake in FN's thinking was found. Corrected theory\nby Murphy and Good (MG) made theoretical FN plots slightly curved. This causes\ndifficulties when attempting to extract precise values of emission\ncharacterization parameters from straight lines fitted to experimental FN\nplots. Improved mathematical understanding, from 2006 onwards, has now enabled\na new FE data-plot form, the \"Murphy-Good plot\". This plots\nln{Im/(Vm)**(2-({\\eta}/6)} vs 1/Vm, where {\\eta} depends only on local work\nfunction. Modern (\"21st century\") MG theory predicts that a theoretical MG plot\nshould be \"almost exactly\" straight. This makes precise extraction of\nwell-defined characterization parameters from ideal I_m(V_m) data much easier.\nThis article gives the theory needed to extract characterization parameters\nfrom MG plots, setting it within the framework of wider difficulties in\ninterpreting FE Im(Vm) data (among them, use of the \"planar emission\napproximation\"). Careful use of MG plots could also help remedy other problems\nin FE technological literature. It is argued MG plots should now supersede FN\nplots."
    },
    {
        "anchor": "Surface states and related quantum interference in \\textit{ab initio}\n  electron transport: Shockley surface states (SS) have attracted much attention due to their role\nin various physical phenomena occurring at surfaces. It is also clear from\nexperiments that they can play an important role in electron transport.\nHowever, accurate incorporation of surface states in $\\textit{ab initio}$\nquantum transport simulations remains still an unresolved problem. Here we go\nbeyond the state-of-the-art non-equilibrium Green's function formalism through\nthe evaluation of the self-energy in real-space, enabling electron transport\nwithout using artificial periodic in-plane conditions. We demonstrate the\nmethod on three representative examples based on Au(111): a clean surface, a\nmetallic nanocontact, and a single-molecule junction. We show that SS can\ncontribute more than 30\\% of the electron transport near the Fermi energy. A\nsignificant and robust transmission drop is observed at the SS band edge due to\nquantum interference in both metallic and molecular junctions, in good\nagreement with experimental measurements. The origin of this interference\nphenomenon is attributed to the coupling between bulk and SS transport channels\nand it is reproduced and understood by tight-binding model. Furthermore, our\nmethod predicts much better quantized conductance for metallic nanocontacts.",
        "positive": "Microscopic origin of low frequency flux noise in Josephson circuits: We analyze the data and discuss their implications for the microscopic origin\nof the low frequency flux noise in superconducting circuits. We argue that this\nnoise is produced by spins at the superconductor insulator boundary whose\ndynamics is due to RKKY interaction. We show that this mechanism explains size\nindependence of the noise, different frequency dependences of the spectra\nreported in large and small SQUIDs and gives the correct intensity for\nrealistic parameters."
    },
    {
        "anchor": "Spin-flip inelastic electron tunneling spectroscopy in atomic chains: We present a theoretical study of the spin transport properties of\nmono-atomic magnetic chains with a focus on the spectroscopical features of the\nI-V curve associated to spin-flip processes. Our calculations are based on the\ns-d model for magnetism with the electron transport treated at the level of the\nnon-equilibrium Green's function formalism. Inelastic spin-flip scattering\nprocesses are introduced perturbatively via the first Born approximation and an\nexpression for the associated self-energy is derived. The computational method\nis then applied to describe the I-V characteristics and its derivatives of one\ndimensional chains of Mn atoms and the results are then compared to available\nexperimental data. We find a qualitative and quantitative agreement between the\ncalculated and the experimental conductance spectra. Significantly we are able\nto describe the relative intensities of the spin excitation features in the I-V\ncurve, by means of a careful analysis of the spin transition selection rules\nassociated to the atomic chains.",
        "positive": "Tunneling Anisotropic Magnetoresistance: A spin-valve like tunnel\n  magnetoresistance using a single magnetic layer: We introduce a new class of spintronics devices in which a spin-valve like\neffect results from strong spin-orbit coupling in a single ferromagnetic layer\nrather than from injection and detection of a spin-polarized current by two\ncoupled ferromagnets. The effect is observed in a\nnormal-metal/insulator/ferromagnetic-semiconductor tunneling device. This\nbehavior is caused by the interplay of the anisotropic density of states in\n(Ga,Mn)As with respect to the magnetization direction, and the two-step\nmagnetization reversal process in this material."
    },
    {
        "anchor": "Modulation of Noise in Submicron GaAs/AlGaAs Hall Devices by Gating: We present a systematic characterization of fluctuations in submicron Hall\ndevices based on GaAs/AlGaAs two-dimensional electron gas heterostructures at\ntemperatures between 1.5 K to 60 K. A large variety of noise spectra, from 1/f\nto Lorentzian, are obtained by gating the Hall devices. The noise level can be\nreduced by up to several orders of magnitude with a moderate gate voltage of\n0.2 V, whereas the carrier density increases less than 60% in the same range.\nThe significant dependence of the Hall noise spectra on temperature and gate\nvoltage is explained in terms of the switching processes related to impurities\nin n-AlGaAs.",
        "positive": "Novel magnetic topological insulator FeBi$_2$Te$_4$ with controllable\n  topological quantum phase: Here, we report a new intrinsic magnetic topological insulator FeBi$_2$Te$_4$\nbased on first-principles calculations and it can achieve a rich topological\nphase under pressure modulation. Without pressure, we predict that both\nFeBi$_2$Te$_4$ ferromagnetic and antiferromagnetic orders are non-trivial\ntopological insulators. Furthermore, FeBi$_2$Te$_4$ of FM-z order will undergo\na series of phase transitions from topological insulator to semimetals and then\nto trivial insulator under pressure. Finally, we further clarify and verify\ntopological phase transitions with low-energy effective model calculations.\nThis topological phase transition process is attributed to the synergy of the\nmagnetic moment and the spin-orbit coupling. The unique topological properties\nof FeBi$_2$Te$_4$ will be of great interest in driving the development of\nquantum effects."
    },
    {
        "anchor": "Fluctuation properties of acoustic phonons generated by ultrafast\n  optical excitation of a quantum dot: We study theoretically the fluctuation properties of acoustic phonons created\nin a semiconductor quantum dot after ultrafast optical excitation. An\nexcitation with a single ultrafast pulse creates an exciton confined to the\nquantum dot, which is coupled to longitudinal acoustic phonons. This leads to\nthe formation of a polaron in the quantum dot accompanied by the emission of a\nphonon wave packet. We show that the fluctuations of the lattice displacement\nassociated with the wave packet after a single laser pulse excitation in\nresonance with the exciton transition are always larger than their respective\nvacuum values. Manipulating the exciton with a second pulse can result in a\nreduction of the fluctuations below their vacuum limit, which means that the\nphonons are squeezed. We show that the squeezing properties of the wave packet\nstrongly depend on the relative phase and the time delay between the two laser\npulses.",
        "positive": "Field-induced dissociation of excitons in two-dimensional MoS$_{2}$/hBN\n  heterostructures: Atomically thin semi-conductors are characterized by strongly bound excitons\nwhich govern the optical properties of the materials below and near the band\nedge. Efficient conversion of photons into electrical current requires, as a\nfirst step, the dissociation of the exciton into free electrons and holes. Here\nwe calculate the dissociation rates of excitons in monolayer MoS$_2$ as a\nfunction of an applied in-plane electric field. The dissociation rates are\nobtained as the inverse lifetime of the resonant states of a two-dimensional\nHydrogenic Hamiltonian which describes the exciton within the Mott-Wannier\nmodel. The resonances are computed using complex scaling, and the effective\nmasses and screened electron-hole interaction defining the Hydrogenic\nHamiltonian are computed from first-principles. For field strengths above 0.1\nV/nm the dissociation lifetime is shorter than 1 picosecond, which is shorter\nthan the lifetime of other, competing, decay mechanisms. Interestingly,\nencapsulation of the \\moly layer in just two layers of hBN, enhances the\ndissociation rate by around one order of magnitude due to the increased\nscreening showing that dielectric engineering is an effective way to control\nexciton lifetimes in two-dimensional materials."
    },
    {
        "anchor": "Parametric oscillation, frequency mixing and injection locking of\n  strongly coupled nanomechanical resonator modes: We study locking phenomena of two strongly coupled, high-quality factor\nnanomechanical resonator modes subject to a common parametric drive at a single\ndrive frequency. By controlled dielectric gradient forces we tune the resonance\nfrequencies of the flexural in-plane and out-of-plane oscillation of the high\nstress silicon nitride string through their mutual avoided crossing. For the\ncase of the strong common parametric drive signal-idler generation via\nparametric oscillation is observed, analogously to the framework of nonlinear\noptical effects in an optical parametric oscillator. Frequency tuning of the\nsignal and idler resonances is demonstrated. When the resonance frequencies of\nsignal and idler get closer to each other, partial injection locking, injection\npulling and complete injection locking to half of the drive frequency occurs\ndepending on the pump strength. Furthermore, satellite resonances,\nsymmetrically off-set from signal and idler by their beat-note, are observed\nwhich can be attributed to degenerate four-wave-mixing in the highly nonlinear\nmechanical oscillations.",
        "positive": "Sliding ferroelectric memories and synapses: Ferroelectric materials with switchable electric polarization hold great\npromise for a plethora of emergent applications, such as post-Moore's law\nnanoelectronics, beyond-Boltzmann transistors, non-volatile memories, and\nabove-bandgap photovoltaic devices. Recent advances have uncovered an exotic\nsliding ferroelectric mechanism, which endows to design atomically thin\nferroelectrics from non-ferroelectric parent monolayers. Although notable\nprogress has been witnessed in understanding its fundamental properties,\nfunctional devices based on sliding ferroelectrics, the key touchstone toward\napplications, remain elusive. Here, we demonstrate the rewritable, non-volatile\nmemory devices at room-temperature utilizing a two-dimensional (2D) sliding\nferroelectric semiconductor of rhombohedral-stacked bilayer molybdenum\ndisulfide. The 2D sliding ferroelectric memories (SFeMs) show superior\nperformances with a large memory window of >8V, a high conductance ratio of\nabove 106, a long retention time of >10 years, and a programming endurance\ngreater than 104 cycles. Remarkably, flexible SFeMs are achieved with\nstate-of-the-art performances competitive to their rigid counterparts and\nmaintain their performances post bending over 103 cycles. Furthermore,\nsynapse-specific Hebbian forms of plasticity and image recognition with a high\naccuracy of 97.81% are demonstrated based on flexible SFeMs. Our work\ndemonstrates the sliding ferroelectric memories and synaptic plasticity on both\nrigid and flexible substrates, highlighting the great potential of sliding\nferroelectrics for emerging technological applications in brain-inspired\nin-memory computing, edge intelligence and energy-efficient wearable\nelectronics."
    },
    {
        "anchor": "Monolithic TCAD Simulation of Phase-Change Memory (PCM/PRAM) + Ovonic\n  Threshold Switch (OTS) Selector Device: Owing to the increasing interest in the commercialization of phase-change\nmemory (PCM) devices, a number of TCAD models have been developed for their\nsimulation. These models formulate the melting, amorphization and\ncrystallization of phase-change materials as well as their extreme conductivity\ndependence on both electric field and temperature into a set of\nself-consistently-solved thermoelectric and phase-field partial-differential\nequations. However, demonstrations of the ability of such models to match\nactual experimental results are rare. In addition, such PCM devices also\nrequire a so-called selector device - such as an Ovonic Threshold Switching\n(OTS) device - in series for proper memory operation. However, monolithic\nsimulation of both the PCM and OTS selector device in a single simulation is\nlargely absent from the literature, despite its potential value for material-\nand design-space explorations. It is the goal of this work to first\ncharacterize a PCM device in isolation against experimental data, then to\ndemonstrate the qualitative behavior of a simulated OTS device in isolation and\nfinally to perform a single monolithic simulation of the PCM + OTS device\nwithin the confines of a commercially available TCAD solver: GTS Framework.",
        "positive": "Electronic structure of graphene hexagonal flake subjected to triaxial\n  stress: The electronic properties of a triaxially strained hexagonal graphene flake\nwith either armchair or zig-zag edges are investigated using molecular dynamics\nsimulations and tight-binding calculations.\n  We found that: i) the pseudo-magnetic field in the strained graphene flakes\nis not uniform neither in the center nor at the edge of zig-zag terminated\nflakes, ii) the pseudo-magnetic field is almost zero in the center of armchair\nterminated flakes but increases dramatically near the edges, iii) the\npseudo-magnetic field increases linearly with strain, for strains lower than\n15$%$ while growing non-linearly beyond this threshold, iv) the local density\nof states in the center of the zig-zag hexagon exhibits pseudo-Landau levels\nwith broken sub-lattice symmetry in the zero'th pseudo-Landau level, and in\naddition there is a shift in the Dirac cone due to strain induced scalar\npotentials. This study provides a realistic model of the electronic properties\nof inhomogeneously strained graphene where the relaxation of the atomic\npositions is correctly included together with strain induced modifications of\nthe hopping terms up to next-nearest neighbors."
    },
    {
        "anchor": "Direct Optical Excitation of Quantum-Degenerate Exciton States in\n  Semiconductors: Quantum electrodynamic calculations predict that truly incoherent light can\nbe used to efficiently generate quantum-degenerate exciton population states.\nResonant incoherent excitation directly converts photons into excitons with\nvanishing center of mass momentum. The populated exciton state possesses\nlong-range order, is very stable against perturbations, and should be\nobservable via its unusual directional and density dependence in luminescence\nmeasurements.",
        "positive": "Effect of electron-phonon scattering on shot noise in nanoscale\n  junctions: We investigate the effect of electron-phonon inelastic scattering on shot\nnoise in nanoscale junctions in the regime of quasi-ballistic transport. We\npredict that when the local temperature of the junction is larger than its\nlowest vibrational mode energy $eV_c$, the inelastic contribution to shot noise\n(conductance) increases (decreases) with bias as $V$ ($\\sqrt{V}$). The\ncorresponding Fano factor thus increases as $\\sqrt{V}$. We also show that the\ninelastic contribution to the Fano factor saturates with increasing thermal\ncurrent exchanged between the junction and the bulk electrodes to a value\nwhich, for $V>>V_c$, is independent of bias. A measurement of shot noise may\nthus provide information about the local temperature and heat dissipation in\nnanoscale conductors."
    },
    {
        "anchor": "Uniaxial Strain Induced Topological Phase Transition in\n  Bismuth-Tellurohalide-Graphene Heterostructures: We explore the electronic structure and topological phase diagram of\nheterostructures formed of graphene and ternary bismuth tellurohalide layers.\nWe show that mechanical strain inherently present in fabricated samples could\ninduce a topological phase transition in single-sided heterostructures, turning\nthe sample into a novel experimental realisation of a time reversal invariant\ntopological insulator. We construct an effective tight binding description for\nlow energy excitations and fit the model's parameters to ab initio band\nstructures. We propose a simple approach for predicting phase boundaries as a\nfunction of mechanical distortions and hence gain a deeper understanding on how\nthe topological phase in the considered system may be engineered.",
        "positive": "Anisotropic magnetoresistance of GaAs two-dimensional holes: Experiments on high-quality GaAs (311)A two-dimensional holes at low\ntemperatures reveal a remarkable dependence of the magnetoresistance, measured\nwith an in-plane magnetic field ($B$), on the direction of $B$ relative to both\nthe crystal axes and the current direction. The magnetoresistance features, and\nin particular the value of $B$ above which the resistivity exhibits an\ninsulating behavior, depend on the orientation of $B$. To explain the data, the\nanisotropic band structure of the holes and a re-population of the\nspin-subbands in the presence of $B$, as well as the coupling of the orbital\nmotion to $B$, need to be taken into account."
    },
    {
        "anchor": "Verwey transition in single magnetite nanoparticles: We present a tunnel spectroscopy study of the electronic spectrum of single\nmagnetite \\chemform{Fe_3O_4} nanoparticles trapped between nanometer-spaced\nelectrodes. The Verwey transition is clearly identified in the current\nvoltage-characteristics where we find that the transition temperature is\nelectric field dependent. The data show the presence of localized states at\nhigh energy, $\\varepsilon \\sim 0.6eV$, which can be attributed to polaron\nstates. At low energy, the density of states (DOS) is suppressed at the\napproach of the Verwey transition. Below the Verwey transition, a gap, $\\Delta\n\\sim 300meV$, is observed in the spectrum. In contrast, no gap is observed in\nthe high temperature phase, implying that electronic transport in this phase is\npossibly due to polaron hopping with activated mobility.",
        "positive": "Decoherence of many-spin systems in NMR: From molecular characterization\n  to an environmentally induced quantum dynamical phase transition: The control of open quantum systems has a fundamental relevance for fields\nranging from quantum information processing to nanotechnology. Typically, the\nsystem whose coherent dynamics one wants to manipulate, interacts with an\nenvironment that smoothly degrades its quantum dynamics. Thus, a precise\nunderstanding of the inner mechanisms of this process, called \"decoherence\", is\ncritical to develop strategies to control the quantum dynamics. In this thesis\nwe solved the generalized Liouville-von Neumann quantum master equation to\nobtain the dynamics of many-spin systems interacting with a spin bath. We also\nsolve the spin dynamics within the Keldysh formalism. Both methods lead to\nidentical solutions and together gave us the possibility to obtain numerous\nphysical predictions that contrast well with Nuclear Magnetic Resonance\nexperiments. We applied these tools for molecular characterizations,\ndevelopment of new numerical methodologies and the control of quantum dynamics\nin experimental implementations. But, more important, these results contributed\nto fundamental physical interpretations of how quantum dynamics behaves in open\nsystems. In particular, we found a manifestation of an environmentally induced\nquantum dynamical phase transition."
    },
    {
        "anchor": "Memresistors and non-memristive zero-crossing hysteresis curves: It has been erroneously asserted by the circuit theorist Leon Chua that all\nzero-crossing pinched hysteresis curves define memristors. This claim has been\nused by Stan Williams of HPLabs to assert that all forms of RRAM and phase\nchange memory are memristors. This paper demonstrates several examples of\ndynamic systems which fall outside of the constraints of memristive systems and\nyet also produce the same type of zero-crossing hysteresis curves claimed as a\nfingerprint for a memristor. This establishes that zero-crossing hysteresis\nserves as insufficient evidence for a memristor. Keywords- nonlinear dynamic\nsystems, memresistor, phase change memory, RRAM, ReRAM",
        "positive": "Conformation dependent magnetotransport in a single handed helical\n  geometry: Conformation dependent circular current is investigated in a single handed\nhelical geometry in presence of magnetic flux $\\phi$ within a Hartree-Fock mean\nfield approach. The helical model is described by a set of non-planar rings\nconnected by some vertical bonds where each ring is formed by introducing a\nnon-zero hopping between the atoms $a$ and $b$ as shown in Fig.1. By stretching\nand compressing the geometry, circular current can be regulated significantly\nand thus the system can be exploited to design current controlled device at the\nnano-scale level. The proximity effect between the atomic sites $a$ and $b$ is\nalso discussed in detail which exhibits interesting results."
    },
    {
        "anchor": "Gate-Based High Fidelity Spin Read-out in a CMOS Device: The engineering of electron spin qubits in a compact unit cell embedding all\nquantum functionalities is mandatory for large scale integration. In\nparticular, the development of a high-fidelity and scalable spin readout method\nremains an open challenge. Here we demonstrate high-fidelity and robust spin\nreadout based on gate reflectometry in a CMOS device comprising one qubit dot\nand one ancillary dot coupled to an electron reservoir to perform readout. This\nscalable method allows us to read out a spin with a fidelity above 99% for 1 ms\nintegration time. To achieve such fidelity, we exploit a latched spin blockade\nmechanism that requires electron exchange between the ancillary dot and the\nreservoir. We show that the demonstrated high read-out fidelity is fully\npreserved up to 0.5 K. This results holds particular relevance for the future\nco-integration of spin qubits and classical control electronics.",
        "positive": "Microwave quantum optics and electron transport through a metallic dot\n  strongly coupled to a transmission line cavity: We investigate theoretically the properties of the photon state and the\nelectronic transport in a system consisting of a metallic quantum dot strongly\ncoupled to a superconducting microwave transmission line cavity. Within the\nframework of circuit quantum electrodynamics we derive a Hamiltonian for\narbitrary strong capacitive coupling between the dot and the cavity. The\ndynamics of the system is described by a quantum master equation, accounting\nfor the electronic transport as well as the coherent, non-equilibrium\nproperties of the photon state. The photon state is investigated, focusing on,\nfor a single active mode, signatures of microwave polaron formation and the\neffects of a non-equilibrium photon distribution. For two active photon modes,\nintra mode conversion and polaron coherences are investigated. For the\nelectronic transport, electrical current and noise through the dot and the\ninfluence of the photon state on the transport properties are at the focus. We\nidentify clear transport signatures due to the non-equilibrium photon\npopulation, in particular the emergence of superpoissonian shot-noise at\nultrastrong dot-cavity couplings."
    },
    {
        "anchor": "Failure of the local density approximation in time-dependent spin\n  density functional theory: It has been known for some time that the exchange-correlation potential in\ntime-dependent density functional theory is an intrinsically nonlocal\nfunctional of the density as soon as one goes beyond the adiabatic\napproximation. In this paper we show that a much more severe nonlocality\nproblem, with a completely different physical origin, plagues the\nexchange-correlation potentials in time-dependent spin density functional\ntheory. We show how the use of the spin current density as the basic variable\nsolves this problem, and we provide an explicit local expression for the\nexchange-correlation fields as functionals of the spin currents.",
        "positive": "Collinear scattering and long-lived excitations in two-dimensional\n  electron fluids: For a long time, it has been thought that 2D Fermi gases could support\nlong-lived excitations, thanks to the collinear quasiparticle scattering\ncontrolled by phase space constraints at a 2D Fermi surface. We present a\ndirect calculation that reveals such excitations. The excitation lifetimes are\nfound to exceed the fundamental bound set by Landau Fermi-liquid theory by a\nfactor as large as $(T_F/T)^\\alpha$ with $\\alpha \\approx 2$. These excitations\nrepresent Fermi-surface modulations of an odd parity, one per each odd angular\nmomentum. To explain this surprising behavior, we employ a connection between\nthe linearized quantum kinetic equation and the dynamics of a fictitious\nquantum particle moving in a 1D reflectionless ${\\rm sech^2}$ potential. In\nthis framework, we identify the long-lived excitations in Fermi gases as zero\nmodes that arise from supersymmetry."
    },
    {
        "anchor": "Quantitative investigation of the inverse Rashba-Edelstein effect in\n  Bi/Ag and Ag/Bi on YIG: The inverse Rashba-Edelstein effect (IREE) is a spin conversion mechanism\nthat recently attracts attention in spintronics and condensed matter physics.\nIn this letter, we report an investigation of the IREE in Bi/Ag by using\nferrimagnetic insulator yttrium iron garnet (YIG). We prepared two types of\nsamples with opposite directions of the Rashba field by changing a stacking\norder of Bi and Ag. An electric current generated by the IREE was observed from\nboth stacks, and an efficiency of spin conversion -characterized by the IREE\nlength- was estimated by taking into account a number of contributions left out\nin previous studies. This study provides a further insight into the IREE spin\nconversion mechanism: important step towards achieving efficient spin-charge\nconversion devices.",
        "positive": "Slowdown of nonequilibrium dynamics in gapped `qubit' chains: We solve the nonequilibrium dynamics of qubits or quantum spin chains (s=1/2)\nmodeled by an anisotropic XY Hamiltonian, when the initial condition is\nprepared as a spatially inhomogeneous state of the magnetization. Infinite\nsystems are studied analytically, yielding a universal relaxation driven by\nquantum fluctuations. Particular long-lived excitations are found, for which\nthe relaxation time diverges as a consequence of constructive quantum\ninterference at degenerate stationary points. Those states are intrinsically\nentangled and may be of interest for performing quantum computation. We also\nnumerically analyze finite samples to assess the extent of size effects."
    },
    {
        "anchor": "Tunable magnetoresistance in an asymmetrically coupled single molecule\n  junction: Phenomena that are highly sensitive to magnetic fields can be exploited in\nsensors and non-volatile memories. The scaling of such phenomena down to the\nsingle molecule level may enable novel spintronic devices. Here we report\nmagnetoresistance in a single molecule junction arising from negative\ndifferential resistance that shifts in a magnetic field at a rate two orders of\nmagnitude larger than Zeeman shifts. This sensitivity to the magnetic field\nproduces two voltage-tunable forms of magnetoresistance, which can be selected\nvia the applied bias. The negative differential resistance is caused by\ntransient charging of an iron phthalocyanine (FePc) molecule on a single layer\nof copper nitride (Cu2N) on a Cu(001) surface, and occurs at voltages\ncorresponding to the alignment of sharp resonances in the filled and empty\nmolecular states with the Cu(001) Fermi energy. An asymmetric voltage-divider\neffect enhances the apparent voltage shift of the negative differential\nresistance with magnetic field, which inherently is on the scale of the Zeeman\nenergy. These results illustrate the impact that asymmetric coupling to\nmetallic electrodes can have on transport through molecules, and highlight how\nthis coupling can be used to develop molecular spintronic applications.",
        "positive": "Emergent Mott insulators and non-Hermitian conservation laws in an\n  interacting bosonic chain with noninteger filling and nonreciprocal hopping: We investigate the ground state and quantum dynamics of an interacting\nbosonic chain with the nonreciprocal hopping. In sharp contrast to its\nHermitian counterpart, the ground state can support Mott insulators in systems\nwith noninteger filling due to the competition between nonreciprocal hopping\nand the on-site interaction. For the quantum dynamics, conservation laws for\nnon-Hermitian systems manifest a stark difference from their Hermitian\ncounterpart. In particular, for any Hermitian operator that commutes with the\nHamiltonian operator, its expectation value is guaranteed to be nonconserved in\nthe non-Hermitian quantum dynamics. To systematically identify the\nnon-Hermitian conservation law, we establish a generic approach for\nconstructing the conserved quantities in non-Hermitian many-body quantum\nsystems with completely real spectra, and illustrate it concretely by the\nsystem under study. The direct experimental observation of Mott insulators in\nsystems with noninteger filling and non-Hermitian conservation laws can be\nperformed by ultracold atoms in optical lattices with the engineered\nnonreciprocal hopping."
    },
    {
        "anchor": "Optomechanical circuits for nanomechanical continuous variable quantum\n  state processing: We propose and analyze a nanomechanical architecture where light is used to\nperform linear quantum operations on a set of many vibrational modes. Suitable\namplitude modulation of a single laser beam is shown to generate squeezing,\nentanglement, and state-transfer between modes that are selected according to\ntheir mechanical oscillation frequency. Current optomechanical devices based on\nphotonic crystals may provide a platform for realizing this scheme.",
        "positive": "Molecular emission near metal interfaces: the polaritonic regime: The strong coupling of a dense layer of molecular excitons with\nsurface-plasmon modes in a metal gives rise to polaritons (hybrid light-matter\nstates) called plexcitons. Surface plasmons cannot directly emit into (or be\nexcited by) free-space photons due to the fact that energy and momentum\nconservation cannot be simultaneously satisfied in photoluminescence. Most\nplexcitons are also formally non-emissive, even though they can radiate via\nmolecules upon localization due to disorder and decoherence. However, a\nfraction of them are bright even in the presence of such deleterious processes.\nIn this letter, we theoretically discuss the superradiant emission properties\nof these bright plexcitons, which belong to the upper energy branch and reveal\nhuge photoluminescence enhancements compared to bare excitons. Our study\ngeneralizes the well-known problem of molecular emission next to a metal\ninterface to collective molecular states and provides new design principles for\nthe control of photophysical properties of molecular aggregates using\npolaritonic strategies."
    },
    {
        "anchor": "Quantum Imaging of Single-Atom Spin-Splitting in a Monolayer\n  Semiconductor: Theoretical work has suggested that monolayer MoS2 doped with Mn should\nbehave as a two-dimensional dilute magnetic semiconductor, which would open up\npossibilities for spintronic applications, device physics, and novel ground\nstates. The magnetic properties on Mn dopants in MoS2 are dependent on the\nmid-gap impurity states of said dopants as well as the sites of dopant\nincorporation and dopant concentration. In this work we use STM/STS to\ncharacterize multiple impurity types associated with Mn dopants in MoS2, and\nuse ring features that appear in spectral maps due to tip-induced band bending\nto investigate the nature of the mid-gap impurity states. The doublet nature of\nthe rings and comparison to DFT calculations show that the Mn states exhibit\nstrong spin splitting which can be quantified. We used scanned MOKE experiments\nto extend these magnetization measurements from atomic scale to mm scales, and\ndetect the spin susceptibility signal which increases with Mn concentration.\nThese experiments show that single Mn atoms in MoS2 function as active\nunscreened magnetic moments in the TMD monolayer, and can be harnessed for spin\nphysics applications and science.",
        "positive": "Experimental identification of critical condition for drastically\n  enhancing thermoelectric power factor of two-dimensional layered materials: Nano-structuring is an extremely promising path to high performance\nthermoelectrics. Favorable improvements in thermal conductivity are attainable\nin many material systems, and theoretical work points to large improvements in\nelectronic properties. However, realization of the electronic benefits in\npractical materials has been elusive experimentally. A key challenge is that\nexperimental identification of the quantum confinement length, below which the\nthermoelectric power factor is significantly enhanced, remains elusive due to\nlack of simultaneous control of size and carrier density. Here we investigate\ngate tunable and temperature-dependent thermoelectric transport in $\\gamma$\nphase indium selenide ($\\gamma$ InSe, n type semiconductor) samples with\nthickness varying from 7 to 29 nm. This allows us to properly map out dimension\nand doping space. Combining theoretical and experimental studies, we reveal\nthat the sharper pre-edge of the conduction-band density of states arising from\nquantum confinement gives rise to an enhancement of the Seebeck coefficient and\nthe power factor in the thinner InSe samples. Most importantly, we\nexperimentally identify the role of the competition between quantum confinement\nlength and thermal de Broglie wavelength in the enhancement of power factor.\nOur results provide an important and general experimental guideline for\noptimizing the power factor and improving the thermoelectric performance of\ntwo-dimensional layered semiconductors."
    },
    {
        "anchor": "Manipulation of edge states in microwave artificial graphene: Edge states are one important ingredient to understand transport properties\nof graphene nanoribbons. We study experimentally the existence and the internal\nstructure of edge states under uniaxial strain of the three main edges: zigzag,\nbearded, and armchair. The experiments are performed on artificial microwave\ngraphene flakes, where the wavefunctions are obtained by direct imaging. We\nshow that uniaxial strain can be used to manipulate the edge states: a single\nparameter controls their existence and their spatial extension into the ribbon.\nBy combining tight-binding approach and topological arguments, we provide an\naccurate description of our experimental findings. A new type of zero-energy\nstate appearing at the intersection of two edges, namely the corner state, is\nalso observed and discussed.",
        "positive": "Current-voltage (I-V) characteristics of armchair graphene nanoribbons\n  under uniaxial strain: The current-voltage (I-V) characteristics of armchair graphene nanoribbons\nunder a local uniaxial tension are investigated by using first principles\nquantum transport calculations. It is shown that for a given value of\nbias-voltage, the resulting current depends strongly on the applied tension.\nThe observed trends are explained by means of changes in the band gaps of the\nnanoribbons due to the applied uniaxial tension. In the course of plastic\ndeformation, the irreversible structural changes and derivation of carbon\nmonatomic chains from graphene pieces can be monitored by two-probe transport\nmeasurements."
    },
    {
        "anchor": "Comment on ``Topological Oscillations of the Magnetoconductance in\n  Disordered GaAs Layers'': In a recent Letter, Murzin et. al. [Phys. Rev. Lett., vol. 92, 016802 (2004)]\ninvestigated \"instanton effects\" in the magneto resistance data taken from\nsamples with heavily Si-doped GaAs layers at low temperatures. This topological\nissue originally arose in the development of a microscopic theory of quantum\nHall effect some 20 years ago. The investigations by Murzin et. al., however,\ndo not convey the correct ideas on scaling that have emerged over the years in\nthe general theory of quantum transport.",
        "positive": "A fast quantum interface between different spin qubit encodings: Single-spin qubits in semiconductor quantum dots proposed by Loss and\nDiVincenzo (LD qubits) hold promise for universal quantum computation with\ndemonstrations of a high single-qubit gate fidelity above 99.9 % and two-qubit\ngates in conjunction with a long coherence time. However, initialization and\nreadout of a qubit is orders of magnitude slower than control, which is\ndetrimental for implementing measurement-based protocols such as\nerror-correcting codes. In contrast, a singlet-triplet (ST) qubit, encoded in a\ntwo-spin subspace, has the virtue of fast readout with high fidelity and\ntunable coupling to the electric field. Here, we present a hybrid system which\nbenefits from the different advantages of these two distinct spin-qubit\nimplementations. A quantum interface between the two codes is realized by\nelectrically tunable inter-qubit exchange coupling. We demonstrate a\ncontrolled-phase (CPHASE) gate that acts within 5.5 ns, much faster than the\nmeasured dephasing time of 211 ns. The presented hybrid architecture will be\nuseful to settle remaining key problems with building scalable spin-based\nquantum computers."
    },
    {
        "anchor": "Boundary Condition Analysis of First and Second Order Topological\n  Insulators: We analytically study boundary conditions of the Dirac fermion models on a\nlattice, which describe the first and second order topological insulators. We\nobtain the dispersion relations of the edge and hinge states by solving these\nboundary conditions, and clarify that the Hamiltonian symmetry may provide a\nconstraint on the boundary condition. We also demonstrate the edgehinge analog\nof the bulk-edge correspondence, in which the nontrivial topology of the gapped\nedge state ensures gaplessness of the hinge state.",
        "positive": "Review of the Low-Frequency 1/f Noise in Graphene Devices: Low-frequency noise with a spectral density that depends inversely on\nfrequency (f) has been observed in a wide variety of systems including current\nfluctuations in resistors, intensity fluctuations in music and signals in human\ncognition. In electronics, the phenomenon, which is known as 1/f noise, flicker\nnoise or excess noise, hampers the operation of numerous devices and circuits,\nand can be a significant impediment to development of practical applications\nfrom new materials. Graphene offers unique opportunities for studying 1/f noise\nbecause of its 2D structure and carrier concentration tuneable over a wide\nrange. The creation of practical graphene-based devices will also depend on our\nability to understand and control the low-frequency 1/f noise in this material\nsystem. Here, I review the characteristic features of 1/f noise in graphene and\nfew-layer graphene, and examine the implications of such noise for the\ndevelopment of graphene-based electronics including high-frequency devices and\nsensors."
    },
    {
        "anchor": "Hole Spin Helix: Anomalous Spin Diffusion in Anisotropic Strained Hole\n  Quantum Wells: We obtain the spin-orbit interaction and spin-charge coupled transport\nequations of a two-dimensional heavy hole gas under the influence of strain and\nanisotropy. We show that a simple two-band Hamiltonian can be used to describe\nthe holes. In addition to the well-known cubic hole spin-orbit interaction,\nanisotropy causes a Dresselhaus-like term, and strain causes a Rashba term. We\ndiscover that strain can cause a shifting symmetry of the Fermi surfaces for\nspin up and down holes. We predict an enhanced spin lifetime associated with a\nspin helix standing wave similar to the Persistent Spin Helix which exists in\nthe two-dimensional electron gas with equal Rashba and Dresselhaus spin-orbit\ninteractions. These results may be useful both for spin-based experimental\ndetermination of the Luttinger parameters of the valence band Hamiltonian and\nfor creating long-lived spin excitations.",
        "positive": "RKKY coupling in graphene: We study the carrier-mediated exchange interaction, the so-called RKKY\ncoupling, between two magnetic moments in graphene using exact diagonalization\non the honeycomb lattice. By using the tight-binding nearest neighbor band\nstructure of graphene we avoid the use of a momentum cut-off which plagues\nresults in the Dirac continuum model formulation. We extract both the short and\nlong impurity-impurity distance behavior and show several corrections to\nearlier long distance results. In the bulk the RKKY coupling is proportional to\n$1/|{\\bf R}|^3$ and displays $(1+\\cos(2{\\bf k}_D\\cdot {\\bf R})$-type\noscillations. A-A sublattice coupling is always ferromagnetic whereas A-B\nsubattice coupling is always antiferromagnetic and three times as large. We\nalso study the effect of edges in zigzag graphene nanoribbons (ZGNRs) and find\nthat for impurities on the edge, the RKKY coupling decays exponentially because\nof the localized zero energy edge states. For impurities inside a ZGNR the bulk\ncharacteristics are quickly regained."
    },
    {
        "anchor": "Nonequilibrium spin noise in a quantum dot ensemble: The spin noise in singly charged self-assembled quantum dots is studied\ntheoretically and experimentally under the influence of a perturbation,\nprovided by additional photoexcited charge carriers. The theoretical\ndescription takes into account generation and relaxation of charge carriers in\nthe quantum dot system. The spin noise is measured under application of above\nbarrier excitation for which the data are well reproduced by the developed\nmodel. Our analysis demonstrates a strong difference of the recharging dynamics\nfor holes and electrons in quantum dots.",
        "positive": "Ballistic reversible gates matched to bit storage: Plans for an\n  efficient CNOT gate using fluxons: New computing technologies are being sought near the end of CMOS transistor\nscaling, meanwhile superconducting digital, i.e., single-flux quantum (SFQ),\nlogic allows incredibly efficient gates which are relevant to the impending\ntransition. In this work we present a proposed reversible logic, including gate\nsimulations and schematics under the name of Reversible Fluxon Logic (RFL). In\nthe widest sense it is related to SFQ-logic, however it relies on (some\napproximately) reversible gate dynamics and promises higher efficiency than\nconventional SFQ which is logically irreversible. Our gates use fluxons, a type\nof SFQ which has topological-particle characteristics in an undamped Long\nJosephson junction (LJJ). The collective dynamics of the component Josephson\njunctions (JJs) enable ballistic fluxon motion within LJJs as well as good\nenergy preservation of the fluxon for JJ-circuit gates. For state changes, the\ngates induce switching of fluxon polarity during resonant scattering at an\ninterface between different LJJs. Related to the ballistic nature of fluxons in\nLJJ, the gates are powered, almost ideally, only by data fluxon momentum in\nstark contrast to conventionally damped logic gates which are powered\ncontinuously with a bias. At first the fundamental Identity and NOT gates are\nintroduced. Then 2-bit gates are discussed, including the IDSN gate which\nactually allows low fluxon-number inputs for more than 4 input states. A\ndigital CNOT, an important milestone for 2-bit reversible superconducting\ngates, is planned as a central result. It uses a store and launch gate to stop\nand then later route a fluxon. This use of the store and launch gate allows a\nclocked CNOT gate and synchronization within. The digital CNOT gate could\nenable high efficiency relative to conventional irreversible gates and shows\nthe utility of the IDSN as a reversible gate primitive."
    },
    {
        "anchor": "Current driven \"plasmonic boom\" instability in three-dimensional gated\n  periodic ballistic nanostructures: A new approach of using distributed transmission line analogy for solving\ntransport equations for ballistic nanostructures is applied for solving the\nthree dimensional problem of the electron transport in gated ballistic\nnanostructures with periodically changing width. The structures with the\nvarying width allow for modulation of the electron drift velocity while keeping\nthe plasma velocity constant. We predict that in such structures biased by a\nconstant current, a periodic modulation of the electron drift velocity due the\nvarying width results in the instability of the plasma waves if the electron\ndrift velocity to plasma wave velocity ratio changes from below to above unity.\nThe physics of such instability is similar to that of the sonic boom, but, in\nthe periodically modulated structures, this analog of the sonic boom is\nrepeated many times leading to a larger increment of the instability. The\nconstant plasma velocity in the sections of different width leads to the\nresonant excitation of the unstable plasma modes with the varying bias current.\nThis effect (that we refer to as the super plasmonic boom condition) results in\na strong enhancement of the instability. The predicted instability involves the\noscillating dipole charge carried by the plasma waves. The plasmons can be\nefficiently coupled to the terahertz (THz) electromagnetic radiation due to the\nperiodic geometry of the gated structure. Our estimates show that the analyzed\ninstability should enable powerful tunable terahertz electronic sources.",
        "positive": "Extraction of emission parameters for large-area field emitters, using a\n  technically complete Fowler-Nordheim-type equation: In papers on cold field electron emission from large area field emitters\n(LAFEs), it has become widespread practice to publish a misleading\nFowler-Nordheim-type (FN-type) equation. This equation over-predicts the\nLAFE-average current density by a large highly-variable factor thought to\nusually lie between 1000 and 1000 000 000. This equation, although often\nreferenced to FN's 1928 paper, is a simplified equation used in undergraduate\nteaching, does not apply unmodified to LAFEs, and does not appear in the 1928\npaper. Technological LAFE papers often do not cite any theoretical work more\nrecent than 1928, and often do not comment on the discrepancy between theory\nand experiment. This usage has occurred widely, in several high-profile\nAmerican and UK applied-science journals, and in various other places. It does\nnot inhibit practical LAFE development, but can give a misleading impression of\npotential LAFE performance to non-experts. This paper shows how the misleading\nequation can be replaced by a conceptually complete FN-type equation that uses\nthree high-level correction factors. One of these, or a combination of two of\nthem, may be useful as an additional measure of LAFE quality; this paper\ndescribes how to estimate factor values using experimental data. Suggestions\nare made for improved engineering practice in reporting LAFE results. Some of\nthese should help to prevent situations arising whereby an equation appearing\nin high-profile applied-science journals is used to support statements that an\nengineering regulatory body might deem to involve professional negligence."
    },
    {
        "anchor": "Graphene disk in a solenoid magnetic potential: Aharonov-Bohm effect\n  without a two-slit-like setup: The Aharonov-Bohm effect allows one to demonstrate the physical\nmeaningfulness of magnetic vector potential by passing the current in zero\nmagnetic field regions.\n  In the standard (a {\\em two-slit-like}) setup a conducting ring is pierced by\nmagnetic flux and the quantum interference for an electron passing\nsimultaneously the two ring arms is observed. Here we show, by analyzing the\ntransport via evanescent waves, that the ballistic Corbino disk in graphene\nsubjected to a solenoid magnetic potential may exhibit the conductance\noscillations of the Aharonov-Bohm kind although the current flows through a\nsingle conducting element only.",
        "positive": "Cascade donor-acceptor organic ferroelectric layers, between graphene\n  sheets, for solar cell applications: Organic ferroelectric layers sandwiched between the graphene sheets are\npresented as a model of the solar cell. The investigated systems display many\nadvantageous properties: 1) the cascade energy-levels alignment, 2)\nsimultaneous donor and acceptor character depending on the charge-carrier\ndirection, 3) the charge-transfer excitonic type, 4) the induced polarization\nof the electrodes, leading to a substantial work-function change of the anode\nand cathode - around +/-1.5 eV, respectively."
    },
    {
        "anchor": "Electric Aharonov-Bohm effect without a loop in a Cooper pair box: We predict the force-free scalar Aharonov-Bohm effect of a Cooper pair box in\nan electric field at a distance without forming a closed path of the\ninterfering charges. The superposition of different charge states plays a major\nrole in eliminating the closed loop, which is distinct from the original\ntopological Aharonov-Bohm effect. The phase shift is determined by the\ncharge-state-dependent local field interaction energy. In addition, our\nproposed setup does not require a pulse experiment for fast switching of a\npotential, which eliminates the major experimental obstacle for observing the\nideal electric Aharonov-Bohm effect.",
        "positive": "Voltage-Dependent Differential Conductance (dI/dV) Imaging of a\n  Polymer:Fullerene Bulk-Heterojunction: With scanning tunneling spectroscopy (STS), we probed differential\nconductance (dI/dV) images of P3HT:PCBM bulk-heterojunctions (BHJs). Since the\nmaterials are seen energetically in dI/dV images, the imaging process provides\nopportunities to view the nano-domains of the components in the BHJ. The images\nwere recorded at different voltages to bring out the interface region between\nthe two materials as well. The density of states (DOS) spectra of pristine\nmaterials provided location of energy levels of the polymer and the fullerene\nin forming energy diagram with a type-II alignment from the view-point of\ncharge carriers. DOS spectra recorded in the P3HT:PCBM heterojunction in\naddition yielded energies that deviated from those of the components indicating\nbending of energy levels at the interface region."
    },
    {
        "anchor": "Full orientation control of epitaxial MoS2 on hBN assisted by substrate\n  defects: Inversion asymmetry in two-dimensional materials grants them fascinating\nproperties such as spin-coupled valley degrees of freedom and piezoelectricity,\nbut at the cost of inversion domain boundaries if the epitaxy of the grown 2D\nlayer -- on a polar substrate -- cannot adequately distinguish what are often\nnear-degenerate 0{\\deg} and 180{\\deg} orientations. We employ first-principles\ncalculations to identify a method to lift this near-degeneracy: the energetic\ndistinction between eclipsed and staggered configurations during nucleation at\na point defect in the substrate. For monolayer MoS2 grown on hexagonal boron\nnitride, the predicted defect complex can be more stable than common MoS2 point\ndefects because it is both a donor-acceptor pair and a Frenkel pair shared\nbetween adjacent layers of a 2D heterostack. Orientation control is verified in\nexperiments that achieve ~90% consistency in the orientation of as-grown\ntriangular MoS2 flakes on hBN, as confirmed by aberration-corrected\nscanning/transmission electron microscopy. This defect-enhanced orientational\nepitaxy could provide a general mechanism to break the near-degeneracy of\n0/180{\\deg} orientations of polar 2D materials on polar substrates, overcoming\na long-standing impediment to scalable synthesis of single-crystal 2D\nsemiconductors.",
        "positive": "Origin and magnitude of 'designer' spin-orbit interaction in graphene on\n  semiconducting transition metal dichalcogenides: We use a combination of experimental techniques to demonstrate a general\noccurrence of spin-orbit interaction (SOI) in graphene on transition metal\ndichalcogenide (TMD) substrates. Our measurements indicate that SOI is\nultra-strong and extremely robust, despite it being merely\ninterfacially-induced, with neither graphene nor the TMD substrates changing\ntheir structure. This is found to be the case irrespective of the TMD material\nused, of the transport regime, of the carrier type in the graphene band, and of\nthe thickness of the graphene multilayer. Specifically, we perform weak\nantilocalization measurements as the simplest and most general diagnostic of\nSOI, and show that the spin relaxation time is very short in all cases\nregardless of the elastic scattering time. Such a short spin-relaxation time\nstrongly suggests that the SOI originates from a modification of graphene band\nstructure. We confirmed this expectation by measuring a gate-dependent beating,\nand a corresponding frequency splitting, in the low-field Shubnikov-de Haas\nmagneto-resistance oscillations in high quality bilayer graphene on WSe$_2$.\nThese measurements provide an unambiguous diagnostic of a SOI-induced splitting\nin the electronic band structure, and their analysis allows us to determine the\nSOI coupling constants for the Rashba term and the so-called spin-valley\ncoupling term, i.e., the terms that were recently predicted theoretically for\ninterface-induced SOI in graphene. The magnitude of the SOI splitting is found\nto be on the order of 10 meV, more than 100 times greater than the SOI\nintrinsic to graphene. Both the band character of the interfacially induced\nSOI, as well as its robustness and large magnitude make graphene-on-TMD a\npromising system to realize and explore a variety of spin-dependent transport\nphenomena, such as, in particular, spin-Hall and valley-Hall topological\ninsulating states."
    },
    {
        "anchor": "Electrically tunable exchange splitting in bilayer graphene on monolayer\n  Cr$_2$X$_2$Te$_6$ with X=Ge, Si, and Sn: We investigate the electronic band structure and the proximity exchange\neffect in bilayer graphene on a family of ferromagnetic multilayers\nCr$_2$X$_2$Te$_6$, X=Ge, Si, and Sn, with first principles methods. In each\ncase the intrinsic electric field of the heterostructure induces an orbital gap\non the order of 10 meV in the graphene bilayer. The proximity exchange is\nstrongly band dependent. For example, in the case of Cr$_2$Ge$_2$Te$_6$, the\nlow-energy valence band of bilayer graphene has exchange splitting of 8 meV,\nwhile the low energy conduction band's splitting is 30 times less (0.3 meV).\nThis striking discrepancy stems from the layer-dependent hybridization with the\nferromagnetic substrate. Remarkably, applying a vertical electric field of a\nfew V/nm reverses the exchange, allowing us to effectively turn ON and OFF\nproximity magnetism in bilayer graphene. Such a field-effect should be generic\nfor van der Waals bilayers on ferromagnetic insulators, opening new\npossibilities for spin-based devices.",
        "positive": "Correlation-Induced Sensitivity and Non-Hermitian Skin Effect of\n  Quasiparticles: Non-Hermitian (NH) Hamiltonians have been shown to exhibit unique signatures,\nincluding the NH skin effect and an exponential spectral sensitivity with\nrespect to boundary conditions. Here, we investigate as to what extent these\nremarkable phenomena, recently predicted and observed in a broad range of\nsettings, may also occur in closed correlated fermionic systems that are\ngoverned by a Hermitian many-body Hamiltonian. There, an effectively NH\nquasiparticle description naturally arises in the Green's function formalism\ndue to inter-particle scattering that represents an inherent source of\ndissipation. As a concrete platform we construct an extended interacting\nSu-Schrieffer-Heeger (SSH) model subject to varying boundary conditions, which\nwe analyze using exact diagonalization and non-equilibrium Green's function\nmethods. That way, we clearly identify the presence of the aforementioned NH\nphenomena in the quasi-particle properties of this Hermitian model system."
    },
    {
        "anchor": "Spin-pumping-induced inverse spin-Hall effect in Nb/Ni80Fe20 bilayers\n  and its strong decay across the superconducting transition temperature: We quantify the spin Hall angle {\\theta}SH and spin diffusion length lsd of\nNb from inverse spin-Hall effect (iSHE) measurements in Nb/Ni80Fe20 bilayers\nunder ferromagnetic resonance. By varying the Nb thickness tNb and comparing to\na Ni80Fe20/Pt reference sample, room temperature values of {\\theta}SH and lsd\nfor Nb are estimated to be approximately -0.001 and 30 nm, respectively. We\nalso investigate the iSHE as a function of temperature T for different tNb.\nAbove the superconducting transition temperature Tc of Nb, a clear\ntNb-dependent T evolution of the iSHE is observed whereas below Tc, the iSHE\nvoltage drops rapidly and is below the sensitivity of our measurement setup at\na lower T. This suggests the strong decay of the quasiparticle (QP)\ncharge-imbalance relaxation length across Tc, as supported by an additional\ninvestigation of the iSHE in a different sample geometry along with model\ncalculation. Our finding suggests careful consideration should be made when\ndeveloping superconductor spin-Hall devices that intend to utilize QP-mediated\nspin-to-charge interconversion.",
        "positive": "Superparamagnetic relaxation in Cu_{x}Fe_{3-x}O_{4} (x=0.5 and x=1)\n  nanoparticles: The scope of this article is to report very detailed results of the\nmeasurements of magnetic relaxation phenomena in the new\nCu$_{0.5}$Fe$_{2.5}$O$_{4}$ nanoparticles and known CuFe$_{2}$O$_{4}$\nnanoparticles. The size of synthesized particles is (6.5$\\pm $1.5)nm. Both\nsamples show the superparamagnetic behaviour, with the well-defined phenomena\nof blocking of magnetic moment. This includes the splitting of\nzero-field-cooled and field-cooled magnetic moment curves, dynamical\nhysteresis, slow quasi-logarithmic relaxation of magnetic moment below blocking\ntemperature. The scaling of the magnetic moment relaxation data at different\ntemperatures confirms the applicability of the simple thermal relaxation model.\nThe two copper-ferrites with similar structures show significantly different\nmagnetic anisotropy density and other magnetic properties. Investigated systems\nexhibit the consistency of all obtained results."
    },
    {
        "anchor": "Spontaneous emission of Schr\u00f6dinger cats in a waveguide at ultrastrong\n  coupling: Josephson circuits provide a realistic physical setup where the light-matter\nfine structure constant can become of order one, allowing to reach a regime\ndominated by non-perturbative effects beyond standard quantum optics. Simple\nprocesses, such as spontaneous emission, thus acquire a many-body character,\nthat can be tackled using a new description of the time-dependent state vector\nin terms of quantum-superposed coherent states. We find that spontaneous atomic\ndecay at ultrastrong coupling leads to the emission of spectrally broad\nSchr\\\"odinger cats rather than of monochromatic single photons. These cats\nstates remain partially entangled with the emitter at intermediate stages of\nthe dynamics, even after emission, due to a large separation in time scales\nbetween fast energy relaxation and exponentially slow decoherence. Once\ndecoherence of the qubit is finally established, quantum information is\ncompletely transfered to the state of the emitted cat.",
        "positive": "Probing the minigap in topological insulator-based Josephson junctions\n  under radio frequency irradiation: Recently, a contact-resistance-measurement method was developed to detect the\nminigap, hence the Andreev bound states (ABSs), in Josephson junctions\nconstructed on the surface of three-dimensional topological insulators (3D\nTIs). In this work, we further generalize that method to the circumstance with\nradio frequency (rf) irradiation. We find that with the increase of rf power,\nthe measured minigap becomes broadened and extends to higher energies, in a way\nsimilar to the rf power dependence of the outer border of the Shapiro step\nregion. We show that the corresponding data of contact resistance under rf\nirradiation can be well interpreted by using the resistively shunted Josephson\njunction model (RSJ model) and the Blonder-Tinkham-Klapwijk (BTK) theory. Our\nfindings could be useful when using the contact-resistance-measurement method\nto study the Majorana-related physics in topological insulator-based Josephson\njunctions under rf irradiation."
    },
    {
        "anchor": "Large optical conductivity of Dirac semimetal Fermi arc surfaces states: Fermi arc surface states, a hallmark of topological Dirac semimetals, can\nhost carriers that exhibit unusual dynamics distinct from that of their parent\nbulk. Here we find that Fermi arc carriers in intrinsic Dirac semimetals\npossess a strong and anisotropic light matter interaction. This is\ncharacterized by a large Fermi arc optical conductivity when light is polarized\ntransverse to the Fermi arc; when light is polarized along the Fermi arc, Fermi\narc optical conductivity is significantly muted. The large surface spectral\nweight is locked to the wide separation between Dirac nodes and persists as a\nlarge Drude weight of Fermi arc carriers when the system is doped. As a result,\nlarge and anisotropic Fermi arc conductivity provides a novel means of\noptically interrogating the topological surfaces states of Dirac semimetals.",
        "positive": "Topological protection brought to light by the time-reversal symmetry\n  breaking: Recent topological band theory distinguishes electronic band insulators with\nrespect to various symmetries and topological invariants, most commonly, the\ntime reversal symmetry and the $\\rm Z_2$ invariant. The interface of two\ntopologically distinct insulators hosts a unique class of electronic states --\nthe helical states, which shortcut the gapped bulk and exhibit spin-momentum\nlocking. The magic and so far elusive property of the helical electrons, known\nas topological protection, prevents them from coherent backscattering as long\nas the underlying symmetry is preserved. Here we present an experiment which\nbrings to light the strength of topological protection in one-dimensional\nhelical edge states of a $\\rm Z_2$ quantum spin-Hall insulator in HgTe. At low\ntemperatures, we observe the dramatic impact of a tiny magnetic field, which\nresults in an exponential increase of the resistance accompanied by giant\nmesoscopic fluctuations and a gap opening. This textbook Anderson localization\nscenario emerges only upon the time-reversal symmetry breaking, bringing the\nfirst direct evidence of the topological protection strength in helical edge\nstates."
    },
    {
        "anchor": "Exchange-split multiple Rydberg series of excitons in anisotropic quasi\n  two-dimensional ReS$_{2}$: We perform a polarization-resolved magnetoluminescence study of excitons in\nReS$_2$. We observe that two linearly polarized Rydberg series of excitons are\naccompanied by two other Rydberg series of dark excitons, brightened by an\nin-plane magnetic field. All series extrapolate to the same single-electron\nbandgap, indicating that the observed excitons originate either from the same\nvalley or from two valleys related by the inversion symmetry, and are split by\nexchange interaction. To interpret our observations of the magnetic\nbrightening, we have to assume the dominant spin-orbit coupling to be\nIsing-like, which hints at an approximate symmetry of the electronic states in\nReS$_2$ which is higher than the crystal symmetry $C_i$.",
        "positive": "The Haldane model under nonuniform strain: We study the Haldane model under strain using a tight-binding approach, and\ncompare the obtained results with the continuum-limit approximation. As in\ngraphene, nonuniform strain leads to a time-reversal preserving pseudo-magnetic\nfield that induces (pseudo) Landau levels. Unlike a real magnetic field, strain\nlifts the degeneracy of the zeroth pseudo Landau levels at different valleys.\nMoreover, for the zigzag edge under uniaxial strain, strain removes the\ndegeneracy within the pseudo-Landau levels by inducing a tilt in their energy\ndispersion. The latter arises from next-to-leading order corrections to the\ncontinuum-limit Hamiltonian, which are absent for a real magnetic field. We\nshow that, for the lowest pseudo-Landau levels in the Haldane model, the\ndominant contribution to the tilt is different from graphene. In addition,\nalthough strain does not strongly modify the dispersion of the edge states,\ntheir interplay with the pseudo-Landau levels is different for the armchair and\nzigzag ribbons. Finally, we study the effect of strain in the band structure of\nthe Haldane model at the critical point of the topological transition, thus\nshedding light on the interplay between non-trivial topology and strain in\nquantum anomalous Hall systems."
    },
    {
        "anchor": "Topological Yu-Shiba-Rusinov chain from spin-orbit coupling: We investigate the possibility of realizing a topological state in the\nimpurity band formed by a chain of classical spins embedded in a\ntwo-dimensional singlet superconductor with Rashba spin-orbit coupling. In\ncontrast to similar proposals which require a helical spin texture of the\nimpurity spins for a nontrivial topology, here we show that spin-flip\ncorrelations due to the spin-orbit coupling in the superconductor produces a\ntopological state for ferromagnetic alignment of the impurity spins. From the\nBogoliubov-de Gennes equations we derive an effective tight-binding model for\nthe subgap states which resembles a spinless superconductor with long-range\nhopping and pairing terms. We evaluate the topological invariant, and show that\na topologically non-trivial state is generically present in this model.",
        "positive": "Disorder and metal-insulator transitions in Weyl semimetals: The Weyl semimetal (WSM) is a newly proposed quantum state of matter. It has\nWeyl nodes in bulk excitations and Fermi arcs surface states. We study the\neffects of disorder and localization in WSMs and find three exotic phase\ntransitions. (I) Two Weyl nodes near the Brillouin zone boundary can be\nannihilated pairwise by disorder scattering, resulting in the opening of a\ntopologically nontrivial gap and a transition from a WSM to a three-dimensional\n(3D) quantum anomalous Hall state. (II) When the two Weyl nodes are well\nseparated in momentum space, the emergent bulk extended states can give rise to\na direct transition from a WSM to a 3D diffusive anomalous Hall metal. (III)\nTwo Weyl nodes can emerge near the zone center when an insulating gap closes\nwith increasing disorder, enabling a direct transition from a normal band\ninsulator to a WSM. We determine the phase diagram by numerically computing the\nlocalization length and the Hall conductivity, and propose that the exotic\nphase transitions can be realized on a photonic lattice."
    },
    {
        "anchor": "Fluctuation dissipation relations for strongly correlated\n  out-of-equilibrium circuits: We consider strongly correlated quantum circuits where a dc drive is added on\ntop of an initial out-of-equilibrium (OE) stationary state. Within a\nperturbative approach, we derive unifying OE fluctuation relations for high\nfrequency current noise, shown to be completely determined by zero-frequency\nnoise and dc current. We apply them to the fractional quantum Hall effect at\narbitrary incompressible filling factors, driven by OE sources, without\nknowledge of the underlying model. We show that such OE relations provide\nrobust methods for an unambiguous determination of the fractional charge or of\nkey interaction parameters entering in the exploration of anyonic statistics\nwithin an anyon collider.",
        "positive": "Scalable Transfer-Free Fabrication of MoS$_2$/SiO$_2$ Hybrid\n  Nanophotonic Cavity Arrays with Quality Factors Exceeding 4000: We report the fully-scalable fabrication of a large array of hybrid\nmolybdenum disulfide (MoS$_2$) - silicon dioxide (SiO$_2$) one-dimensional,\nfree-standing photonic-crystal cavities capable of enhancement of the MoS$_2$\nphotoluminescence at the narrow cavity resonance. We demonstrate continuous\ntunability of the cavity resonance wavelength across the entire emission band\nof MoS$_2$ simply by variation of the photonic crystal periodicity. Device\nfabrication started by substrate-scale growth of MoS$_2$ using chemical vapor\ndeposition (CVD) on non-birefringent thermal oxide on a silicon wafer; it was\nfollowed by lithographic fabrication of a photon crystal nanocavity array on\nthe same substrate at more than 50% yield of functional devices. Our cavities\nexhibit three dominant modes with measured linewidths less than 0.2 nm,\ncorresponding to quality factors exceeding 4000. All experimental findings are\nfound to be in excellent agreement with finite difference time domain\nsimulations."
    },
    {
        "anchor": "Impact of surface and laser-induced noise on the spectral stability of\n  implanted nitrogen-vacancy centers in diamond: Scalable realizations of quantum network technologies utilizing the nitrogen\nvacancy center in diamond require creation of optically coherent NV centers in\nclose proximity to a surface for coupling to optical structures. We create\nsingle NV centers by $^{15}$N ion implantation and high-temperature vacuum\nannealing. Origin of the NV centers is established by optically detected\nmagnetic resonance spectroscopy for nitrogen isotope identification. Near\nlifetime-limited optical linewidths ($<$ 60 MHz) are observed for the majority\nof the normal-implant (7$^\\circ$, $\\approx$ 100 nm deep) $^{15}$NV centers.\nLong-term stability of the NV$^-$ charge state and emission frequency is\ndemonstrated. The effect of NV-surface interaction is investigated by varying\nthe implantation angle for a fixed ion-energy, and thus lattice damage profile.\nIn contrast to the normal implant condition, NVs from an oblique-implant\n(85$^\\circ$, $\\approx$ 20 nm deep) exhibit substantially reduced optical\ncoherence. Our results imply that the surface is a larger source of\nperturbation than implantation damage for shallow implanted NVs. This work\nsupports the viability of ion implantation for formation of optically stable NV\ncenters. However, careful surface preparation will be necessary for scalable\ndefect engineering.",
        "positive": "Comparison between entangled and nonentangled two-reservoir Kondo\n  systems: We clarify the difference between entangled and nonentangled two-reservoir\nmesoscopic Kondo systems and reveal the reason why theories using the Keldysh\nformalism, quantum Monte Carlo calculations, and the renormalization group\napproaches cannot explain the line shapes of tunneling conductance of\nmesoscopic Kondo systems measured by using a two-terminal setup but explain\nthose of a three-terminal setup. We emphasize that the previous theories study\na nonentangled system, while real two-reservoir mesoscopic Kondo systems are\nentangled systems in which two reservoirs are within the coherent region. We\nshow that two coherent side peaks appearing in tunneling conductance signify\nthe entanglement between two reservoirs. These side peaks are essential for\nexplaining the experimental observations for tunneling conductance."
    },
    {
        "anchor": "Cavity quantum electrodynamics with charge-controlled quantum dots\n  coupled to a fiber Fabry-Perot cavity: We demonstrate non-perturbative coupling between a single self-assembled\nInGaAs quantum dot and an external fiber-mirror based microcavity. Our results\nextend the previous realizations of tunable microcavities while ensuring\nspatial and spectral overlap between the cavity-mode and the emitter by\nsimultaneously allowing for deterministic charge control of the quantum dots.\nUsing resonant spectroscopy, we show that the coupled quantum dot cavity system\nis at the onset of strong coupling, with a cooperativity parameter of 2. Our\nresults constitute a milestone towards the realization of a high efficiency\nsolid-state spin-photon interface.",
        "positive": "Infrared photoresistance as a sensitive probe of electronic transport in\n  twisted bilayer graphene: We report on observation of the infrared photoresistance of twisted bilayer\ngraphene under continuous quantum cascade laser illumination at a frequency of\n57.1 THz. The photoresistance shows an intricate sign-alternating behavior\nunder variations of temperature and back gate voltage, and exhibits giant\nresonance-like enhancements at certain gate voltages. The structure of the\nphotoresponse correlates with weaker features in the dark dc resistance\nreflecting the complex band structure of twisted bilayer graphene. It is shown\nthat the observed photoresistance is well captured by a bolometric model\ndescribing the electron and hole gas heating, which implies an ultrafast\nthermalization of the photoexcited electron-hole pairs in the whole range of\nstudied temperatures and back gate voltages. We establish that photoresistance\ncan serve a highly sensitive probe of the temperature variations of electronic\ntransport in twisted bilayer graphene."
    },
    {
        "anchor": "Hybrid Higher-Order Topological Skin Modes in the Two-Dimensional\n  Su-Schrieffer-Heeger Model with Nonreciprocal Hoppings: The coexistence of edge states and skin effects provides the topologically\nprotected localized states at the corners of two-dimensional systems. In this\npaper, we realize such corner states in the two-dimensional\nSu-Schrieffer-Heeger model with the nonreciprocal hoppings. For the\ncharacterization of the real line gap topology, we introduce the $\\mathbb{Z}_4$\nBerry phase protected by generalized four-fold rotational symmetry. From the\nphysical picture of the adiabatic connection, we find that the value of the\n$\\mathbb{Z}_4$ Berry predicts the position of edge states. Additionally, by\nusing the winding number, we characterize the point gap topology of the edge\nspectra. From the results of these characterizations by the first-order\ntopological invariants, we find that the pair of values of the $\\mathbb{Z}_4$\nBerry phase and the winging number yields the position of the topologically\nprotected localized states.",
        "positive": "Thermodynamics of Water Entry in Hydrophobic Channels of Carbon\n  Nanotubes: Experiments and computer simulations demonstrate that water spontaneously\nfills the hydrophobic cavity of a carbon nanotube. To gain a quantitative\nthermody- namic understanding of this phenomenon, we use the recently developed\nTwo Phase Thermodynamics (2PT) method to compute translational and rotational\nentropies of confined water molecules inside single-walled carbon nanotubes and\nshow that the increase in energy of a water molecule inside the nanotube is\ncompensated by the gain in its rotational entropy. The confined water is in\nequilibrium with the bulk wa- ter and the Helmholtz free energy per water\nmolecule of confined water is the same as that in the bulk within the accuracy\nof the simulation results. A comparison of translational and rotational spectra\nof water molecules confined in carbon nanotubes with that of bulk water shows\nsignificant shifts in the positions of the spectral peaks that are directly\nrelated to the tube radius."
    },
    {
        "anchor": "Strong eigenfunction correlations near the Anderson localization\n  transition: We study overlap of two different eigenfunctions as compared with\nself-overlap in the framework of an infinite-dimensional version of the\ndisordered tight-binding model. Despite a very sparse structure of the\neigenstates in the vicinity of Anderson transition their mutual overlap is\nstill found to be of the same order as self-overlap as long as energy\nseparation is smaller than a critical value. The latter fact explains\nrobustness of the Wigner-Dyson level statistics everywhere in the phase of\nextended states. The same picture is expected to hold for usual d-dimensional\nconductors, ensuring the $s^{\\beta}$ form of the level repulsion at critical\npoint.",
        "positive": "Gauge fermions with flat bands and anomalous transport via chiral modes\n  from breaking gauge symmetry: The dispersionless longitudinal photon in Maxwell theory is thought of as a\nredundant degree of freedom due to the gauge symmetry. We find that when there\nexist exactly flat bands with zero energy in a condensed matter system, the\nfermion field may locally transform as a gauge field and the system possesses a\ngauge symmetry. As the longitudinal photon, the redundant degrees of freedom\nfrom the flat bands must be gauged away from the physical states. As an\nexample, we study spinless fermions on a generalized Lieb lattice in three\ndimensions. The flat band of the longitudinal fermion induces a gauge symmetry.\nAn external magnetic field breaks this gauge symmetry and emerges a bunch of\nnon-topologically chiral modes. Combining these emergent chiral modes with the\nchiral anomaly mode which is of an opposite chirality, rich anomalous electric\ntransport phenomena exhibit and are expected to be observed in\nPd$_3$Bi$_2$S$_2$ and Ag$_3$Se$_2$Au."
    },
    {
        "anchor": "Remote control of spin polarization of topological corner states: In two-dimensional higher-order topological insulators, the corner states are\nseparated by a non-negligible distance. The crystalline symmetries protect the\nrobustness of their corner states with long-range entanglement, which are\nrobust against time-reversal breaking perturbations. Here, we demonstrate the\npossibility of direct control of the topological corner states by introducing\nthe spin degree of freedom in a rhombus-shaped Kekul\\'{e} nanostructure with\nlocal magnetization and local electric potential. By applying a local\nmagnetization on one corner, the other corner can also be strongly spin\npolarized. By further applying a local electric potential at the same corner,\nthe sign of the spin polarization can be reversed at both corners. We\ndemonstrate the material realization in a $\\gamma$-graphyne nanostructure with\nMn adsorption and Si replacement at one corner by using the first-principles\ncalculations. Our studies give a showcase of the remote correlation of quantum\nstates in higher-order topological materials for spintronic and quantum\napplications.",
        "positive": "Topological superconductivity in proximity to type-II superconductors: One-dimensional systems proximity-coupled to a superconductor can be driven\ninto a topological superconducting phase by an external magnetic field. Here,\nwe investigate the effect of vortices created by the magnetic field in a\ntype-II superconductor providing the proximity effect. We identify different\nways in which the topological protection of Majorana modes can be compromised\nand discuss strategies to circumvent these detrimental effects. Our findings\nare also relevant to topological phases of proximitized quantum Hall edge\nstates."
    },
    {
        "anchor": "A Higher-Order Topological Insulator Phase in a Modulated Haldane Model: We explore topological properties of a modulated Haldane model (MHM) in which\nthe strength of the nearest-neighbor and next-nearest-neighbor terms is made\nunequal and the three-fold rotational symmetry $\\mathcal{C}_3$ is broken by\nintroducing a trimerization term ($|t_{1w(2w)}|< t_{1s(2s)}$) in the\nHamiltonian. Using the parameter $\\eta={t_{1w}}/{t_{1s}}= t_{2w}/t_{2s}$, we\nshow that the MHM supports a transition from the quantum anomalous Hall\ninsulator (QAHI) to a HOTI phase at $\\eta=\\pm 0.5$. The MHM also hosts a\nzero-energy corner mode on a nano-disk that can transition to a trivial\ninsulator without gap-closing when the inversion symmetry is broken. The\ngap-closing critical states are found to be magnetic semimetals with a single\nDirac node which, unlike the classic Haldane model, can move along the\nhigh-symmetry lines in the Brillouin zone. MHM offers a rich tapestry of HOTI\nand other topological and non-topological phases.",
        "positive": "Josephson diode effect derived from short-range coherent coupling: Superconducting devices with broken time-reversal and spatial-inversion\nsymmetries can exhibit novel superconducting phenomena. The observation of\nsuperconducting diode effects, which is applicable for dissipationless\nrectification, provides information on the breaking of such symmetries. We\nexperimentally study a Josephson junction (JJ) coupled to another adjacent JJ\nas a new system exhibiting the superconducting diode effect. We demonstrate\nthat the observed superconducting diode effect can be controlled non-locally\nbased on the phase difference with the adjacent JJ. These results indicate that\nthe time-reversal and spatial-inversion symmetries of a JJ are broken by the\ncoherent coupling to an adjacent JJ, and this enables the engineering of novel\nsuperconducting phenomena mediated by coherent coupling among JJs and\ndevelopment of their applications for superconducting diode devices."
    },
    {
        "anchor": "Visualizing the interplay of Dirac mass gap and magnetism at nanoscale\n  in intrinsic magnetic topological insulators: In intrinsic magnetic topological insulators, Dirac surface state gaps are\nprerequisites for quantum anomalous Hall and axion insulating states.\nUnambiguous experimental identification of these gaps has proved to be a\nchallenge, however. Here we use molecular beam epitaxy to grow intrinsic\nMnBi2Te4 thin films. Using scanning tunneling microscopy/spectroscopy, we\ndirectly visualize the Dirac mass gap and its disappearance below and above the\nmagnetic order temperature. We further reveal the interplay of Dirac mass gaps\nand local magnetic defects. We find that in high defect regions, the Dirac mass\ngap collapses. Ab initio and coupled Dirac cone model calculations provide\ninsight into the microscopic origin of the correlation between defect density\nand spatial gap variations. This work provides unambiguous identification of\nthe Dirac mass gap in MnBi2Te4, and by revealing the microscopic origin of its\ngap variation, establishes a material design principle for realizing exotic\nstates in intrinsic magnetic topological insulators.",
        "positive": "Quantification of the helical morphology of chiral Au nanorods: Chirality in inorganic nanoparticles and nanostructures has gained increasing\nscientific interest, because of the possibility to tune their ability to\ninteract differently with left- and right-handed circularly polarized light. In\nsome cases, the optical activity is hypothesized to originate from a chiral\nmorphology of the nanomaterial. However, quantifying the degree of chirality in\nobjects with sizes of tens of nanometers is far from straightforward. Electron\ntomography offers the possibility to faithfully retrieve the three-dimensional\nmorphology of nanomaterials, but only a qualitative interpretation of the\nmorphology of chiral nanoparticles has been possible so far. We introduce\nherein a methodology that enables us to quantify the helicity of complex chiral\nnanomaterials, based on the geometrical properties of a helix. We demonstrate\nthat an analysis at the single particle level can provide significant insights\ninto the origin of chiroptical properties."
    },
    {
        "anchor": "Electric field effect in boron and nitrogen doped graphene bilayers: Unlike single layer graphene, in the case of $AB$-stacked bilayer graphene\n(BLG) one can induce a non-zero energy gap by breaking the inversion symmetry\nbetween the two layers using a perpendicular electric field. This is an\nessential requirement in field-effect applications, particularly since the\ninduced gap in BLG systems can be further tuned by the magnitude of the\nexternal electric field. Doping is another way to modify the electronic\nproperties of graphene based systems. We investigate here BLG systems doped\nwith boron and nitrogen in the presence of external electric field, in the\nframework of density functional theory (DFT) calculations. Highly doped BLG\nsystems are known to behave as degenerate semiconductors, where the Fermi\nenergy depends on the doping concentration but, in addition, we show that the\nelectronic properties drastically depend also on the applied electric field. By\nchanging the magnitude and the orientation of the electric field, the gap size\nand position relative to the Fermi level may be tuned, essentially controlling\nthe effect of the extrinsic doping. In this context, we discuss in how far the\nexternal electric field may suitably adjust the effective doping and,\nimplicitly, the conduction properties of doped BLG systems.",
        "positive": "The transfer matrix approach to circular graphene quantum dots: We adapt the transfer matrix ($\\T$-matrix) method originally designed for\none-dimensional quantum mechanical problems to solve the circularly symmetric\ntwo-dimensional problem of graphene quantum dots. In similarity to\none-dimensional problems, we show that the generalized $\\T$-matrix contains\nrich information about the physical properties of these quantum dots. In\nparticular, it is shown that the spectral equations for bound states as well as\nquasi-bound states of a circular graphene quantum dot and related quantities\nsuch as the local density of states and the scattering coefficients are all\nexpressed exactly in terms of the $\\T$-matrix for the radial confinement\npotential. As an example, we use the developed formalism to analyse physical\naspects of a graphene quantum dot induced by a trapezoidal radial potential.\nAmong the obtained results, it is in particular suggested that the thermal\nfluctuations and electrostatic disorders may appear as an obstacle to\ncontrolling the valley polarization of Dirac electrons."
    },
    {
        "anchor": "Valley Degenerate 2D Electrons in the Lowest Landau Level: We report low temperature magnetotransport measurements on a high mobility\n(\\mu=325,000 cm^2/V sec) 2D electron system on a H-terminated Si(111) surface.\nWhile low magnetic field data indicate a six-fold valley degenerate system, we\nobserve the integral quantum Hall effect at all filling factors \\nu<=6 and find\nthat \\nu=2 develops in an unusually narrow temperature range. An extended,\nexclusively even numerator, fractional quantum Hall hierarchy occurs\nsurrounding \\nu=3/2, consistent with two-fold valley-degenerate composite\nfermions (CFs). We determine activation energies and estimate the CF mass.",
        "positive": "A new approach to the quantized electrical conductance: The quanta of electrical conductance is derived for a one-dimensional\nelectron gas both by making use of the quasi-classical motion of a quantum\nfluid and by using arguments related to the uncertainty principle. The result\nis extended to a nanowire of finite cross-section area and to electrons in\nmagnetic field, and the quantization of the electrical conductance is shown. An\nadditional application is made to the two-dimensional electron gas."
    },
    {
        "anchor": "Prediction of inelastic light scattering spectra from electronic\n  collective excitations in GaAs/AlGaAs core-multishell nanowires: We predict inelastic light scattering spectra from electron collective\nexcitations in a coaxial quantum well embedded in a core-multishell GaAs/AlGaAs\nnanowire. The complex composition, the hexagonal cross section and the remote\ndoping of typical samples are explicitly included, and the free electron gas is\nobtained by a DFT approach. Inelastic light scattering cross sections due to\ncharge and spin collective excitations belonging to quasi-1D and quasi-2D\nstates, which coexist in such radial heterostructures, are predicted in the\nnon-resonant approximation from a fully three-dimensional multi-subband TDDFT\nformalism. We show that collective excitations can be classified in azimuthal,\nradial and longitudinal excitations, according to the associated density\nfluctuations, and we suggest that their character can be exposed by specific\nspectral dispersion of inelastic light scattering along different planes of the\nheterostructure.",
        "positive": "Phonon impact on optical control schemes of quantum dots: The role of\n  quantum dot geometry and symmetry: Phonons strongly influence the optical control of semiconductor quantum dots.\nWhen modeling the electron-phonon interaction in several theoretical approaches\nthe quantum dot geometry is approximated by a spherical structure, though\ntypical self-assembled quantum dots are strongly lens-shaped. By explicitly\ncomparing simulations of a spherical and a lens-shaped dot using a\nwell-established correlation expansion approach we show that indeed lens-shaped\ndots can be exactly mapped to a spherical geometry when studying the phonon\ninfluence on the electronic system. We also give a recipe to reproduce spectral\ndensities from more involved dots by rather simple spherical models. On the\nother hand, breaking the spherical symmetry has a pronounced impact on the\nspatio-temporal properties of the phonon dynamics. As an example we show that\nfor a lens-shaped quantum dot the phonon emission is strongly concentrated\nalong the direction of the smallest axis of the dot which is important for the\nuse of phonons for the communication between different dots."
    },
    {
        "anchor": "Evidence of Ferrimagnetism in Ferromagnetic La0_{67}Ca0_{33}MnO_3\n  nanoparticle: The present report is dedicated to show that ferromagnetic La0.67Ca0.33MnO3\n(LCMN) particles can be better described in the framework of ferrimagnetic\nmodel. To confirm the ferrimagnetic signature in ferromagnetic LCMN particles,\nthe temperature dependence of the inverse of magnetic susceptibility in the\nparamagnetic state of the samples was taken as a tool of data analysis. The\nobserved ferrimagnetism is understood as an effect of of the core-shell spin\nstructure in LCMN particles.",
        "positive": "Vortex Wall Dynamics and Pinning in Helical Magnets: Domain walls formed by one dimensional array of vortex lines have been\nrecently predicted to exist in disordered helical magnets and multiferroics.\nThese systems are on one hand analogues to the vortex line lattices in type-II\nsuperconductors while on the other hand they propagate in the magnetic medium\nas a domain boundary. Using a long wavelength approach supported by numerical\noptimization we lay out detailed theory for dynamics and structure of such\ntopological fluctuations at zero temperature in presence of weak disorder. We\nshow the interaction between vortex lines is weak. This is the direct\nconsequence of the screening of the vorticity by helical background in the\nsystem. We explain how one can use this result to understand the elasticity of\nthe wall with a vicinal surface approach. Also we show the internal degree of\nfreedom of this array leads to the enhancement of its mobility. We present\nestimates for the interaction and mobility enhancements using the microscopic\nparameters of the system. Finally we determine the range of velocities/force\ndensities in which the internal movement of the vortex wall can be effective in\nits dynamics."
    },
    {
        "anchor": "Direct measurement of the hole-nuclear spin interaction in single\n  quantum dots: We use photoluminescence spectroscopy of ''bright'' and ''dark'' exciton\nstates in single InP/GaInP quantum dots to measure hyperfine interaction of the\nvalence band hole with nuclear spins polarized along the sample growth axis.\nThe ratio of the hyperfine constants for the hole (C) and electron (A) is found\nto be C/A~-0.11. In InP dots the contribution of spin 1/2 phosphorus nuclei to\nthe hole-nuclear interaction is weak, which enables us to determine\nexperimentally the value of C for spin 9/2 indium nuclei as C_In~-5 micro-eV.\nThis high value of C is in good agreement with recent theoretical predictions\nand suggests that the hole-nuclear spin interaction has to be taken into\naccount when considering spin qubits based on holes.",
        "positive": "Coherent spin dynamics of an interwell excitons gas in GaAs/AlGaAs\n  coupled quantum wells: The spin dynamics of an interwell excitons gas has been investigated in n-i-n\nGaAs/AlGaAs coupled quantum wells (CQWs). In these heterostructures the\nelectron and the hole are spatially separated in neighboring quantum wells by a\nnarrow AlAs barrier, when an electric field is applied. The time evolution\nkinetics of the interwell exciton photoluminescence has been measured under\nresonant excitation of the 1sHH intrawell exciton, using a pulsed tunable\nlaser. The formation of a collective exciton phase in time and the temperature\ndependence of its spin relaxation rate have been studied. The spin relaxation\nrate of the interwell excitons is strongly reduced in the collective phase.\nThis observation provides evidence for the coherence of the indirect excitons\ncollective phase at temperatures below a critical $T_c$."
    },
    {
        "anchor": "Even-odd effect for spin current through thin antiferromagnetic\n  insulator: Magnon spin transport in a metal-antiferromagnetic insulator-ferromagnetic\ninsulator heterostructure is considered. The spin current is generated via the\nspin Seebeck effect and in the limit of clean sample where the effects of\ninterface imperfections and lattice defects are excluded. For NiO as an\nantiferromagnetic insulator we have a magnetic order of antiferromagnetically\ncombined planes which are internally in ferromagnetic order. We find that the\nsign of the spin current depends on the magnetization direction of the plane\nnext to the metal resulting in an even-odd effect for the spin current.\nMoreover, as long as damping is excluded, this even-odd effect is the only\nremaining dependence on the NiO thickness for high temperatures.",
        "positive": "The fundamental 1/f noise in monolayer graphene: The quantum indeterminacy caused by non-commutativity of observables at\ndifferent times sets a lower bound on the voltage noise power spectrum in any\nconducting material. This bound is calculated explicitly in the case of\nmonolayer graphene. It is found that account of graphene pseudospin/valley band\nstructure raises the quantum bound by a factor of 7/2 compared to the case of\nspinless charge carriers with a conical energy-momentum dispersion. The bound\npossesses all characteristic properties of 1/f noise, and its dependence on the\ncharge carrier density is congruent to the experimentally observed."
    },
    {
        "anchor": "Silencing noisy 2DEG wafers: Telegraphic noise is one of the most significant problems that arises when\nmaking sensitive measurements with lateral electrostatic devices. In this paper\nwe demonstrate that a wafer which had only produced devices with significant\ntelegraph noise problems can be made to produce 'quiet' devices if a thin\ninsulator layer is placed between the gates and the GaAs/AlGaAs\nheterostructure. A slow drift in the resulting devices is attributed to the\ntrapping of charges within the specific insulator used. This charge can be\nmanipulated, leading to strategies for stabilizing the device.",
        "positive": "A Green's function approach to Topological Insulator junctions with\n  magnetic and superconducting regions: This work presents a Green's function approach, originally implemented in\ngraphene with well-defined edges, to the surface of a strong 3D Topological\nInsulator (TI) with a sequence of proximitized superconducting (S) and\nferromagnetic (F) surfaces. This consists of the derivation of the Green's\nfunctions for each region by the asymptotic solutions method, and their\ncoupling by a tight-binding Hamiltonian with the Dyson equation to obtain the\nfull Green's functions of the system. These functions allow the direct\ncalculation of the momentum-resolved spectral density of states, the\nidentification of subgap interface states, and the derivation of the\ndifferential conductance for a wide variety of configurations of the junctions.\nWe illustrate the application of this method for some simple systems with two\nand three regions, finding the characteristic chiral state of the Quantum\nAnomalous Hall Effect (QAHE) at the NF interfaces, and chiral Majorana modes at\nthe NS interfaces. Finally, we discuss some geometrical effects present in\nthree-region junctions such as weak Fabry-P\\'erot resonances and Andreev bound\nstates."
    },
    {
        "anchor": "Effects of Oxygen Adsorption on the Surface State of Epitaxial Silicene\n  on Ag(111): Epitaxial silicene, which is one single layer of silicon atoms packed in a\nhoneycomb structure, demonstrates a strong interaction with the substrate that\ndramatically affects its electronic structure. The role of electronic coupling\nin the chemical reactivity between the silicene and the substrate is still\nunclear so far, which is of great importance for functionalization of silicene\nlayers. Here, we report the reconstructions and hybridized electronic\nstructures of epitaxial 4x4 silicene on Ag(111), which are revealed by scanning\ntunneling microscopy and angle-resolved photoemission spectroscopy. The\nhybridization between Si and Ag results in a metallic surface state, which can\ngradually decay due to oxygen adsorption. X-ray photoemission spectroscopy\nconfirms the decoupling of Si-Ag bonds after oxygen treatment as well as the\nrelatively oxygen resistance of Ag(111) surface, in contrast to 4x4 silicene\n[with respect to Ag(111)]. First-principles calculations have confirmed the\nevolution of the electronic structure of silicene during oxidation. It has been\nverified experimentally and theoretically that the high chemical activity of\n4x4 silicene is attributable to the Si pz state, while the Ag(111) substrate\nexhibits relatively inert chemical behavior.",
        "positive": "Concurrent magneto-optical imaging and magneto-transport readout of\n  electrical switching of insulating antiferromagnetic thin films: We demonstrate stable and reversible current induced switching of large-area\n($> 100\\;\\mu m^2$) antiferromagnetic domains in NiO/Pt by performing concurrent\ntransport and magneto-optical imaging measurements in an adapted Kerr\nmicroscope. By correlating the magnetic images of the antiferromagnetic domain\nchanges and magneto-transport signal response in these current-induced\nswitching experiments, we disentangle magnetic and non-magnetic contributions\nto the transport signal. Our table-top approach establishes a robust procedure\nto subtract the non-magnetic contributions in the transport signal and extract\nthe spin-Hall magnetoresistance response associated with the switching of the\nantiferromagnetic domains enabling one to deduce details of the\nantiferromagnetic switching from simple transport measurements."
    },
    {
        "anchor": "Charge detection in gate-defined bilayer graphene quantum dots: We report on charge detection in electrostatically-defined quantum dot\ndevices in bilayer graphene using an integrated charge detector. The device is\nfabricated without any etching and features a graphite back gate, leading to\nhigh quality quantum dots. The charge detector is based on a second quantum dot\nseparated from the first dot by depletion underneath a 150 nm wide gate. We\nshow that Coulomb resonances in the sensing dot are sensitive to individual\ncharging events on the nearby quantum dot. The potential change due to single\nelectron charging causes a step-like change (up to 77 %) in the current through\nthe charge detector. Furthermore, the charging states of a quantum dot with\ntunable tunneling barriers and of coupled quantum dots can be detected.",
        "positive": "Exfoliation and van der Waals heterostructure assembly of intercalated\n  ferromagnet Cr1/3TaS2: Ferromagnetic van der Waals (vdW) materials are in demand for spintronic\ndevices with all-two-dimensional-materials heterostructures. Here, we\ndemonstrate mechanical exfoliation of magnetic-atom-intercalated transition\nmetal dichalcogenide Cr1/3TaS2 from its bulk crystal; previously such\nintercalated materials were thought difficult to exfoliate. Magnetotransport in\nexfoliated tens-of-nanometres-thick flakes revealed ferromagnetic ordering\nbelow its Curie temperature TC ~ 110 K as well as strong in-plane magnetic\nanisotropy; these are identical to its bulk properties. Further, van der Waals\nheterostructure assembly of Cr1/3TaS2 with another intercalated ferromagnet\nFe1/4TaS2 is demonstrated using a dry-transfer method. The fabricated\nheterojunction composed of Cr1/3TaS2 and Fe1/4TaS2 with a native Ta2O5 oxide\ntunnel barrier in between exhibits tunnel magnetoresistance (TMR), revealing\npossible spin injection and detection with these exfoliatable ferromagnetic\nmaterials through the vdW junction."
    },
    {
        "anchor": "Structures, Symmetries, Mechanics and Motors of carbon nanotubes: The structures and symmetries of single-walled carbon nanotubes (SWNTs) are\nintroduced in detail. The physical properties of SWNTs induced by their\nsymmetries can be described by tensors in mathematical point of view. It is\nfound that there are 2, 4, and 5 different parameters in the second, third, and\nfourth rank tensors representing electronic conductivity (or static\npolarizability), the second order nonlinear polarizability, and elastic\nconstants of SWNTs, respectively. The values of elastic constants obtained from\ntight-binding method imply that SWNTs might be very weakly anisotropic in\nmechanical properties. The further study on the mechanical properties shows\nthat the elastic shell theory in the macroscopic scale can be applied to carbon\nnanotubes (CNTs) in the mesoscopic scale, as a result, SWNTs can be regarded as\nan isotropic material with Poisson ratio, effective thickness, and Young's\nmodulus being $\\nu=0.34$, $h=0.75$\\AA, $Y=4.70$TPa, respectively, while the\nYoung's moduli of multi-walled carbon nanotubes (MWNTs) are apparent functions\nof the number of layers, $N$, varying from 4.70TPa to 1.04TPa for N=1 to\n$\\infty$. Based on the chirality of CNTs, it is predicted that a new kind of\nmolecular motor driven by alternating voltage can be constructed from double\nwalled carbon nanotubes (DWNTs).",
        "positive": "Fermi surface and nested magnetic breakdown in WTe2: We report a detailed Shubnikov-de Haas (SdH) study on the Weyl type-II\nsemimetal WTe2 in magnetic fields up to 29 T. By using the SdH results to guide\nour density functional theory calculations, we are able to accurately determine\nits Fermi surface by employing a moderate Hubbard U term, which is an essential\nstep in explaining the unusual electronic properties of this much studied\nmaterial. In addition to the fundamental orbits, we observe magnetic breakdown,\nwhich can consistently be explained within the model of a Russian-doll-nested\nFermi surface of electron and hole pockets. The onset of magnetic breakdown in\nWTe2 is solely determined by impurity damping in contrast to magnetic breakdown\nscenarios in other metallic systems."
    },
    {
        "anchor": "Band structure of hydrogenated Si nanosheets and nanotubes: The band structure of fully hydrogenated Si nanosheets and nanotubes are\nelucidated by the use of an empirical tight-binding model. The hydrogenated Si\nsheet is a semiconductor with indirect band gap of about 2.2 eV. The symmetries\nof the wave functions allow us to explain the origin of the gap. We predict\nthat, for certain chiralities, hydrogenated Si nanotubes represent a new type\nof semiconductor, one with co-existing direct and indirect gaps of exactly the\nsame magnitude. This behavior is different from the Hamada rule established for\nnon-hydrogenated carbon and silicon nanotubes. Comparison to an ab initio\ncalculation is made.",
        "positive": "Diffusive and Ballistic Transport in Ultra-thin InSb Nanowire Devices\n  Using a Few-layer-Graphene-AlOx Gate: Quantum devices based on InSb nanowires (NWs) are a prime candidate system\nfor realizing and exploring topologically-protected quantum states and for\nelectrically-controlled spin-based qubits. The influence of disorder on\nachieving reliable topological regimes has been studied theoretically,\nhighlighting the importance of optimizing both growth and nanofabrication. In\nthis work we investigate both aspects. We developed InSb nanowires with\nultra-thin diameters, as well as a new gating approach, involving few-layer\ngraphene (FLG) and Atomic Layer Deposition (ALD)-grown AlOx. Low-temperature\nelectronic transport measurements of these devices reveal conductance plateaus\nand Fabry-P\\'erot interference, evidencing phase-coherent transport in the\nregime of few quantum modes. The approaches developed in this work could help\nmitigate the role of material and fabrication-induced disorder in\nsemiconductor-based quantum devices."
    },
    {
        "anchor": "Possible self-amplification channel for surface plasma waves: Surface plasma waves (SPWs) have been extensively studied in the past two\ndecades with a promise for many applications. However, the effort has so far\nbeen met with limited success. It is widely believed that a major caveat lies\nwith the energy losses experienced by SPWs during their propagation. To\ncompensate for the losses, amplifiers have been designed, which are all\nextrinsic and need an external agent to supply the energy. Here we\ntheoretically show that there exists an intrinsic amplification channel for\nSPWs in the collision-less limit. We pin down the origin of this channel and\nanalytically calculate the amplification rate. Our finding unveils a hitherto\nunchartered yet fundamental property of SPWs and may bear far-reaching\npractical consequences.",
        "positive": "Energy transport via multiphonon processes in graphene: The Dirac dispersion of graphene limits the phase space available for energy\ntransport between electrons and acoustic phonons at temperatures above the\nBloch-Grueneisen temperature. Consequently, energy transport can be dominated\nby supercollision events, involving also other scattering processes. Scattering\nfrom flexural phonons can compensate for the large momentum transfer involved\nin scattering from thermal acoustic phonons, and enables similar supercollision\nevents as disorder. Such multiphonon processes are also allowed by selection\nrules. I show that acoustic-flexural process can in the energy transport be of\nthe same order of magnitude as direct flexural and acoustic phonon processes,\ndepending on electronic screening and mechanical strain."
    },
    {
        "anchor": "Surface-resistance measurements using superconducting stripline\n  resonators: We present a method to measure the absolute surface resistance of conductive\nsamples at a set of GHz frequencies with superconducting lead stripline\nresonators at temperatures 1- 6K. The stripline structure can easily be applied\nfor bulk samples and allows direct calculation of the surface resistance\nwithout the requirement of additional calibration measurements or sample\nreference points. We further describe a correction method to reduce\nexperimental background on high-Q resonance modes by exploiting TEM-properties\nof the external cabling. We then show applications of this method to the\nreference materials gold, tantalum, and tin, which include the anomalous skin\neffect and conventional superconductivity. Furthermore, we extract the complex\noptical conductivity for an all-lead stripline resonator to find a coherence\npeak and the superconducting gap of lead.",
        "positive": "Quantum phase transitions in the systems of parallel quantum dots: We study the low-temperature transport properties of the systems of parallel\nquantum dots described by the N-impurity Anderson model. We calculate the\nquasiparticle scattering phase shifts, spectral functions and correlations as a\nfunction of the gate voltage for N up to 5. For any N, the conductance at the\nparticle-hole symmetric point is unitary. For N >= 2, a transition from\nferromagnetic to antiferromagnetic impurity spin correlations occurs at some\ngate voltage. For N >= 3, there is an additional transition due to an abrupt\nchange in average impurity occupancy. For odd N, the conductance is\ndiscontinuous through both quantum phase transitions, while for even N only the\nmagnetic transition affects the conductance. Similar effects should be\nexperimentally observable in the systems of quantum dots with ferromagnetic\nconduction-band-mediated inter-dot exchange interactions."
    },
    {
        "anchor": "Efficient determination of the Markovian time-evolution towards a\n  steady-state of a complex open quantum system: Master equations are commonly used to describe time evolution of open\nsystems. We introduce a general method for calculating a Markovian solution of\nthe Nakajima-Zwanzig generalized master equation. We do so for a time dependent\ntransport of interacting electrons through a complex nano scale system in a\nphoton cavity. The central system, described by 120 many-body states in a Fock\nspace, is weakly coupled to the external leads. The very diverse relaxation\ntimes of the open system, reflecting radiative or non-radiative transitions,\nrequire information about the time evolution through many orders of magnitude.\nIn our approach, the generalized master equation is mapped from a many-body\nFock space of states to a Liouville space of transitions. We show that this\nresults in a linear equation which is solved exactly through an eigenvalue\nanalysis, which supplies information on the steady state and the time evolution\nof the system.",
        "positive": "Theory of Glide Symmetry Protected Helical Edge States in WTe$_{2}$\n  Monolayer: Helical edge states in quantum spin Hall (QSH) materials are central building\nblocks of topological matter design and engineering. Despite their principal\ntopological protection against elastic backscattering, the level of operational\nstability depends on manifold parameters such as the band gap of the given\nsemiconductor system in the 'inverted' regime, temperature, disorder, and\ncrystal orientation. We theoretically investigate electronic and transport\nproperties of QSH edge states in large gap 1-T' WTe$_{2}$ monolayers. We\nexplore the impact of edge termination, disorder, temperature, and interactions\non experimentally addressable edge state observables, such as local density of\nstates and conductance. We show that conductance quantization can remain\nsurprisingly robust even for heavily disordered samples because of an\nanomalously small edge state decay length and additional protection related to\nthe large direct gap allowed by glide symmetry. From the simulation of\ntemperature-dependent resistance, we find that moderate disorder enhances the\nstability of conductance by localizing bulk states. We evaluate the edge state\nvelocity and Luttinger liquid parameter as functions of the chemical potential,\nfinding prospects for physics beyond linear helical Luttinger liquids in\nsamples with ultra-clean and well-defined edges."
    },
    {
        "anchor": "Charge noise, spin-orbit coupling, and coherence of single-spin qubits: Spin-orbit coupling is ubiquitous in quantum dot quantum computing\narchitectures, and makes spin qubits susceptible to charge noise. We derive a\nHamiltonian describing the effect of spin-orbit and noise on a single-spin\nqubit in a quantum dot. Relaxation is due to noise coupling different orbital\nlevels and is dominated by screened whole charge defects near the dot.\nDephasing stems from noise causing relative fluctuations between orbital\nlevels, and is driven by screened whole charge defects and unscreened dipole\ndefects in the substrate. Dephasing times are vastly different between common\nmaterials such as Si and GaAs. They can be enhanced by increasing gate fields,\nchoosing materials with weak spin-orbit such as Si, making dots narrower, or\nusing accumulation dots.",
        "positive": "Charge transport in a superlattice: a numerical study using moment\n  methods: A semiclassical model of charge transport in a semiconductor superlattice is\nsolved, using moments in the wavenumber direction and finite elements in the\nspatial direction (first order). The selection of numerical methods guarantees\nthe conservation of current while allowing for high accuracy results. When a dc\nvoltage bias is held between the ends of the sample, self-sustaining\noscillations of the current through the superlattice are observed in a narrow\nrange of voltages. the calculated solution displayed the expected accuracy:\nSpectral convergence in the number of moments used, and first-order convergence\nin the number of grid-cells. This result paves the way for higher-order methods\n(in the spatial direction) and the numerical solution of more complex models of\ncharge transport including quantum models based on the Wigner function."
    },
    {
        "anchor": "Flat bands by latent symmetry: Flat energy bands of model lattice Hamiltonians provide a key ingredient in\ndesigning dispersionless wave excitations and have become a versatile platform\nto study various aspects of interacting many-body systems. Their essential\nmerit lies in hosting compactly localized eigenstates which originate from\ndestructive interference induced by the lattice geometry, in turn often based\non symmetry principles. We here show that flat bands can be generated from a\nhidden symmetry of the lattice unit cell, revealed as a permutation symmetry\nupon reduction of the cell over two sites governed by an effective dimer\nHamiltonian. This so-called latent symmetry is intimately connected to a\nsymmetry between possible walks of a particle along the cell sites, starting\nand ending on each of the effective dimer sites. The summed amplitudes of any\neigenstate with odd parity on the effective dimer sites vanish on special site\nsubsets called walk multiplets. We exploit this to construct flat bands by\nusing a latently symmetric unit cell coupled into a lattice via walk multiplet\ninterconnections. We demonstrate that the resulting flat bands are tunable by\ndifferent parametrizations of the lattice Hamiltonian matrix elements which\npreserve the latent symmetry. The developed framework may offer fruitful\nperspectives to analyze and design flat band structures.",
        "positive": "Spin and valley dynamics of excitons in transition metal dichalcogenides\n  monolayers: Monolayers of transition metal dichalcogenides, namely, molybdenum and\ntungsten disulfides and diselenides demonstrate unusual optical properties\nrelated to the spin-valley locking effect. Particularly, excitation of\nmonolayers by circularly polarized light selectively creates electron-hole\npairs or excitons in non-equivalent valleys in momentum space, depending on the\nlight helicity. This allows studying the inter-valley dynamics of charge\ncarriers and Coulomb complexes by means of optical spectroscopy. Here we\npresent a concise review of the neutral exciton fine structure and its spin and\nvalley dynamics in monolayers of transition metal dichalcogenides. It is\ndemonstrated that the long-range exchange interaction between an electron and a\nhole in the exciton is an efficient mechanism for rapid mixing between bright\nexcitons made of electron-hole pairs in different valleys. We discuss the\nphysical origin of the long-range exchange interaction and outline its\nderivation in both the electrodynamical and $\\mathbf k \\cdot \\mathbf p$\napproaches. We further present a model of bright exciton spin dynamics driven\nby an interplay between the long-range exchange interaction and scattering.\nFinally, we discuss the application of the model to describe recent\nexperimental data obtained by time-resolved photoluminescence and Kerr rotation\ntechniques."
    },
    {
        "anchor": "Absence of a metallic phase in charge-neutral graphene with a random gap: It is known that fluctuations in the electrostatic potential allow for\nmetallic conduction (nonzero conductivity in the limit of an infinite system)\nif the carriers form a single species of massless two-dimensional Dirac\nfermions. A nonzero uniform mass $\\bar{M}$ opens up an excitation gap,\nlocalizing all states at the Dirac point of charge neutrality. Here we\ninvestigate numerically whether fluctuations $\\delta M \\gg \\bar{M} \\neq 0$ in\nthe mass can have a similar effect as potential fluctuations, allowing for\nmetallic conduction at the Dirac point. Our negative conclusion confirms\nearlier expectations, but does not support the recently predicted metallic\nphase in a random-gap model of graphene.",
        "positive": "Reversible magnetic domain reorientation induced by magnetic field\n  pulses with fixed direction: Nanoscale magnetic domains with controllable configurations could be used for\nclassical and quantum applications, where the switching of magnetization\nconfigurations is an essential operation for information processing. Here, we\nreport that the magnetic domain reorientation in a notched ferromagnetic\nnanotrack can be realized and effectively controlled by applying uniform\nmagnetic field pulses in a fixed in-plane direction perpendicular to the\nnanotrack. Our micromagnetic simulation results show that the configurations of\nmagnetic domains in the notched nanotrack can be switched between a\nhead-to-head state and a tail-to-tail state in a reversible manner driven by\nmagnetic field pulses, while it is unnecessary to reverse the direction of the\nmagnetic field. Such a unique magnetic domain reorientation dynamics is found\nto depend on magnetic parameters and nanotrack geometries. The reorientation\ndynamics of magnetic domains also depends on the strength and length of the\napplied magnetic field pulse. In addition, we point out that the notches at the\ncenter of the nanotrack play an important role for the stabilization of the\nhead-to-head and tail-to-tail states during the magnetic domain reorientation.\nWe also qualitatively explain the field-induced reorientation phenomenon with a\nsimplified two-dimensional macrospin model. Our results may make it possible to\nbuild spintronic devices driven by a fixed magnetic field. Our findings may\nalso motivate future studies to investigate the classical and quantum\napplications based on nanoscale magnetic domains."
    },
    {
        "anchor": "Electron-phonon interaction effects on the direct gap transitions of\n  nanoscale Si films: This study shows that the dielectric function of crystalline Si quantum wells\n(c-Si QW) is influenced by both carrier confinement and electron-phonon\ninteractions. The energy shifts and lifetime broadening of the excitonic E1\ndirect gap transition of c-Si QWs from 2 to 10 nm are found to have a\nsignificant dimensional and temperature dependence that can be traced to\nchanges in the phonon dispersion of nanoscale films. The influence of\nelectron-phonon interactions on the dielectric function was verified by\naltering the phonon dispersion using different dielectric layers above a 5 nm\nc-Si QW.",
        "positive": "Magnetic field induces giant nonlinear optical response in Weyl\n  semimetals: We study the second-order optical response of Weyl semimetals in the presence\nof a magnetic field. We consider an idealized model of a perfectly linear Weyl\nnode and use the Kubo formula at zero temperature to calculate the intrinsic\ncontribution to photocurrent and second harmonic generation conductivity\ncomponents. We obtain exact analytical expressions applicable at arbitrary\nvalues of frequency, chemical potential, and magnetic field. Our results show\nthat finite magnetic field significantly enhances the nonlinear optical\nresponse in semimetals, while magnetic resonances lead to divergences in\nnonlinear conductivity. In realistic systems, these singularities are\nregularized by a finite scattering rate, but result in pronounced peaks which\ncan be detected experimentally, provided the system is clean and interactions\nare weak. We also perform a semiclassical calculation that complements and\nconfirms our microscopic results at small magnetic fields and frequencies."
    },
    {
        "anchor": "Boundary conditions for Dirac fermions on a terminated honeycomb lattice: We derive the boundary condition for the Dirac equation corresponding to a\ntight-binding model on a two-dimensional honeycomb lattice terminated along an\narbitary direction. Zigzag boundary conditions result generically once the\nboundary is not parallel to the bonds. Since a honeycomb strip with zigzag\nedges is gapless, this implies that confinement by lattice termination does not\nin general produce an insulating nanoribbon. We consider the opening of a gap\nin a graphene nanoribbon by a staggered potential at the edge and derive the\ncorresponding boundary condition for the Dirac equation. We analyze the edge\nstates in a nanoribbon for arbitrary boundary conditions and identify a class\nof propagating edge states that complement the known localized edge states at a\nzigzag boundary.",
        "positive": "Electronic measurements of entropy in meso- and nanoscale systems: Entropy is one of the most fundamental quantities in physics. For systems\nwith few degrees of freedom, the value of entropy provides a powerful insight\ninto its microscopic dynamics, such as the number, degeneracy and relative\nenergies of electronic states, the value of spin, degree of localisation and\nentanglement, and the emergence of exotic states such as non-Abelian anyons. As\nthe size of a system decreases, the conventional methods for measuring entropy,\nbased on heat capacity, quickly become infeasible due to the requirement of\nincreasingly accurate measurements of heat. Several methods to directly measure\nentropy of mesoscopic quantum systems have recently been developed. These\nmethods use electronic measurements of charge, conductance and thermocurrent,\nrather than heat, and have been successfully applied to a wide range of\nsystems, from quantum dots and molecules, to quantum Hall states and twisted\nbilayer graphene. In this Review, we provide an overview of electronic direct\nentropy measurement methods, discuss their theoretical background, compare\ntheir ranges of applicability and look into the directions for their future\nextensions and applications."
    },
    {
        "anchor": "Valence Band Circular Dichroism in non-magnetic Ag/Ru(0001) at normal\n  emission: For the non-magnetic system of Ag films on Ru(0001), we have measured the\ncircular dichroism of photoelectrons emitted along the surface normal, the\ngeometry typically used in photoemission electron microscopy (PEEM).\nPhotoemission spectra were acquired from micrometer-sized regions having\nuniformly thick Ag films on a single, atomically flat Ru terrace. For a single\nAg layer, we find a circular dichroism that exceeds 6% at the d-derived band\nregion around 4.5 eV binding energy. The dichroism decreases as the Ag film\nthickness increases to three atomic layers. We discuss the origin of the\ncircular dichroism in terms of the symmetry lowering that can occur even in\nnormal emission.",
        "positive": "Magnetic Field-Free Giant Magnetoresistance in a Proximity- and\n  Gate-Induced Graphene Spin Valve: Due to its two dimensional nature, ferromagnetism and charge doping can be\ninduced by proximity and electric field effects in graphene. Taking advantage\nof these features, we propose an electrically engineered spin valve by\ncombining two magnetic insulators (using EuO, EuS, or YIG) and three coating\ngates. Two top gates are used to cancel the heavy electron doping's in these\nmagnets and one back gate is used to utilize the normal or half-metallic\nferromagnetisms. We demonstrate that, when the second top gate is tuned to\nutilize the insulating or spin insulating states, huge giant magnetoresistance\n(GMR) at high temperature (several times of $10^5\\%$ at 68K and 100K) can be\nachieved for EuO and YIG. These results imply a distinguished GMR that is\nmagnetism tunable, vertical configured (ferromagnetism versus insulating), and\nmagnetic field-free. Our work may offer a viable path to a tantalizing magnetic\nfield-free spintronics."
    },
    {
        "anchor": "Transient Dynamics of Confined Charges in Quantum Dots in the Sequential\n  Tunnelling Regime: We investigate the time-dependent, coherent, and dissipative dynamics of\nbound particles in single multilevel quantum dots in the presence of sequential\ntunnelling transport. We focus on the nonequilibrium regime where several\nchannels are available for transport. Through a fully microscopic and\nnon-Markovian density matrix formalism we investigate transport-induced\ndecoherence and relaxation of the system. We validate our methodology by also\ninvestigating the Markov limit on our model. We confirm that not only does this\nlimit neglect the coherent oscillations between system states as expected, but\nalso the rate at which the steady state is reached under this limit\nsignificantly differs from the non-Markovian results. By a systematic analysis\nof the decay constants and frequencies of coherent oscillations for the\noff-diagonal elements of the reduced density matrix under various realistic\ntunneling rate anisotropies and energy configurations, we outline a criteria\nfor extended decoherence times.",
        "positive": "Magic angle for barrier-controlled double quantum dots: We show that the exchange interaction of a singlet-triplet spin qubit\nconfined in double quantum dots, when being controlled by the barrier method,\nis insensitive to a charged impurity lying along certain directions away from\nthe center of the double-dot system. These directions differ from the polar\naxis of the double dots by the magic angle, equaling\n$\\arccos\\left(1/\\sqrt{3}\\right)\\approx 54.7^\\circ$, a value previously found in\natomic physics and nuclear magnetic resonance. This phenomenon can be\nunderstood from an expansion of the additional Coulomb interaction created by\nthe impurity, but also relies on the fact that the exchange interaction solely\ndepends on the tunnel coupling in the barrier-control scheme. Our results\nsuggest that for a scaled-up qubit array, when all pairs of double dots rotate\ntheir respective polar axes from the same reference line by the magic angle,\ncross-talks between qubits can be eliminated, allowing clean single-qubit\noperations. While our model is a rather simplified version of actual\nexperiments, our results suggest that it is possible to minimize unwanted\ncouplings by judiciously designing the layout of the qubits."
    },
    {
        "anchor": "Statistical analysis of the figure of merit of a two-level\n  thermoelectric system: a random matrix approach: Using the tools of random matrix theory we develop a statistical analysis of\nthe transport properties of thermoelectric low-dimensional systems made of two\nelectron reservoirs set at different temperatures and chemical potentials, and\nconnected through a low-density-of-states two-level quantum dot that acts as a\nconducting chaotic cavity. Our exact treatment of the chaotic behavior in such\ndevices lies on the scattering matrix formalism and yields analytical\nexpressions for the joint probability distribution functions of the Seebeck\ncoefficient and the transmission profile, as well as the marginal\ndistributions, at arbitrary Fermi energy. The scattering matrices belong to\ncircular ensembles which we sample to numerically compute the transmission\nfunction, the Seebeck coefficient, and their relationship. The exact transport\ncoefficients probability distributions are found to be highly non-Gaussian for\nsmall numbers of conduction modes, and the analytical and numerical results are\nin excellent agreement. The system performance is also studied, and we find\nthat the optimum performance is obtained for half-transparent quantum dots;\nfurther, this optimum may be enhanced for systems with few conduction modes.",
        "positive": "Wigner and Kondo physics in quantum point contacts revealed by scanning\n  gate microscopy: Quantum point contacts exhibit mysterious conductance anomalies in addition\nto well known conductance plateaus at multiples of 2e^2/h. These 0.7 and\nzero-bias anomalies have been intensively studied, but their microscopic origin\nin terms of many-body effects is still highly debated. Here we use the charged\ntip of a scanning gate microscope to tune in situ the electrostatic potential\nof the point contact. While sweeping the tip distance, we observe repetitive\nsplittings of the zero-bias anomaly, correlated with simultaneous appearances\nof the 0.7 anomaly. We interpret this behaviour in terms of alternating\nequilibrium and non-equilibrium Kondo screenings of different spin states\nlocalized in the channel. These alternating Kondo effects point towards the\npresence of a Wigner crystal containing several charges with different\nparities. Indeed, simulations show that the electron density in the channel is\nlow enough to reach one-dimensional Wigner crystallization over a size\ncontrolled by the tip position."
    },
    {
        "anchor": "Fast Single-Charge Sensing with an rf Quantum Point Contact: We report high-bandwidth charge sensing measurements using a GaAs quantum\npoint contact embedded in a radio frequency impedance matching circuit\n(rf-QPC). With the rf-QPC biased near pinch-off where it is most sensitive to\ncharge, we demonstrate a conductance sensitivity of 5x10^(-6) e^(2)/h Hz^(-1/2)\nwith a bandwidth of 8 MHz. Single-shot readout of a proximal few-electron\ndouble quantum dot is investigated in a mode where the rf-QPC back-action is\nrapidly switched.",
        "positive": "From Local to Emergent Altermagnetism: Footprints of Free Fermions Band\n  Topology: Altermagnets are crystallographic rotational symmetry breaking spin-ordered\nstates, possessing a net zero magnetization despite manifesting Kramers\nnon-degenerate bands. Here, we show that momentum-independent local spin\nnematic orders in monolayer, Bernal bilayer and rhombohedral trilayer graphene\ngive rise to $p$-wave, $d$-wave and $f$-wave altermagnets, respectively,\nthereby inheriting the free-fermion topology of linear, bi-quadratic and\nbi-cubic band touchings that are also described in terms of angular momentum\n$\\ell=1,\\; 2$ and $3$ spherical harmonics in the reciprocal space. The same\nconclusions also hold inside a nematic spin-triplet superconductor, featuring\nMajorana altermagnets. Altogether, these findings highlight the importance of\nelectronic band structure in identifying such exotic magnetic orders in real\nmaterials. We depict the effects of in-plane magnetic fields on altermagnets,\nand showcase a novel spin-disordered alter-valleymagnet phase."
    },
    {
        "anchor": "Spin-relaxation anisotropy in a nanowire quantum dot with strong\n  spin-orbit coupling: We study the impacts of the magnetic field direction on the spin-manipulation\nand the spin-relaxation in a one-dimensional quantum dot with strong spin-orbit\ncoupling. The energy spectrum and the corresponding eigenfunctions in the\nquantum dot are obtained exactly. We find that no matter how large the\nspin-orbit coupling is, the electric-dipole spin transition rate as a function\nof the magnetic field direction always has a $\\pi$ periodicity. However, the\nphonon-induced spin relaxation rate as a function of the magnetic field\ndirection has a $\\pi$ periodicity only in the weak spin-orbit coupling regime,\nand the periodicity is prolonged to $2\\pi$ in the strong spin-orbit coupling\nregime.",
        "positive": "Electron confinement in graphene with gate-defined quantum dots: We theoretically analyse the possibility to electrostatically confine\nelectrons in circular quantum dot arrays, impressed on contacted graphene\nnanoribbons by top gates. Utilising exact numerical techniques, we compute the\nscattering efficiency of a single dot and demonstrate that for small-sized\nscatterers the cross-sections are dominated by quantum effects, where resonant\nscattering leads to a series of quasi-bound dot states. Calculating the\nconductance and the local density of states for quantum dot superlattices we\nshow that the resonant carrier transport through such graphene-based\nnanostructures can be easily tuned by varying the gate voltage."
    },
    {
        "anchor": "Transverse shift in crossed Andreev reflection: Crossed Andreev reflection (CAR) is an intriguing effect that occurs in a\nnormal-superconductor-normal junction. In CAR, an incoming electron from one\nterminal is coherently scattered as an outgoing hole into the other terminal.\nHere, we reveal that there exists a transverse spatial shift in CAR, i.e., the\nplane of CAR for the outgoing hole may have a sizable transverse shift from the\nplane of incidence for the incoming electron. We explicitly demonstrate the\neffect in a model system based on Weyl semimetals. We further show that the\neffect is quite general and exists when the terminals have sizable spin-orbit\ncoupling. In addition, we find that the corresponding shift in the elastic\ncotunneling process shows different behaviors, and it vanishes when the two\nterminals are identical. Based on these findings, we suggest possible\nexperimental setups for detecting the effect, which may also offer an\nalternative method for probing CAR.",
        "positive": "SQUIDs based set-up for probing current noise and correlations in\n  three-terminal devices: We have implemented a new experimental set-up for precise measurements of\ncurrent fluctuations in three-terminal devices. The system operates at very low\ntemperatures (30 mK) and is equipped with three SQUIDs as low noise current\namplifiers. A SQUID input coil is connected to each terminal of a sample\nallowing the acquisition of time-dependent current everywhere in the circuit.\nFrom these traces, we can measure the current mean value, the noise and\ncross-correlations between different branches of a device. In this paper we\npresent calibration results of noise and cross-correlations obtained using low\nimpedance macroscopic resistors. From these results we can extract the noise\nlevel of the set-up and show that there are no intrinsic correlations due to\nthe measurement scheme. We also studied noise and correlations as a function of\na DC current and estimated the electronic temperature of various macroscopic\nresistors."
    },
    {
        "anchor": "Jellybean quantum dots in silicon for qubit coupling and on-chip quantum\n  chemistry: The small size and excellent integrability of silicon\nmetal-oxide-semiconductor (SiMOS) quantum dot spin qubits make them an\nattractive system for mass-manufacturable, scaled-up quantum processors.\nFurthermore, classical control electronics can be integrated on-chip,\nin-between the qubits, if an architecture with sparse arrays of qubits is\nchosen. In such an architecture qubits are either transported across the chip\nvia shuttling, or coupled via mediating quantum systems over\nshort-to-intermediate distances. This paper investigates the charge and spin\ncharacteristics of an elongated quantum dot -- a so-called jellybean quantum\ndot -- for the prospects of acting as a qubit-qubit coupler. Charge transport,\ncharge sensing and magneto-spectroscopy measurements are performed on a SiMOS\nquantum dot device at mK temperature, and compared to Hartree-Fock\nmulti-electron simulations. At low electron occupancies where disorder effects\nand strong electron-electron interaction dominate over the electrostatic\nconfinement potential, the data reveals the formation of three coupled dots,\nakin to a tunable, artificial molecule. One dot is formed centrally under the\ngate and two are formed at the edges. At high electron occupancies, these dots\nmerge into one large dot with well-defined spin states, verifying that\njellybean dots have the potential to be used as qubit couplers in future\nquantum computing architectures.",
        "positive": "Spectral properties of excitons in the bilayer graphene: In this paper, we consider the spectral properties of the bilayer graphene\nwith the local excitonic pairing interaction between the electrons and holes.\nWe consider the generalized Hubbard model, which includes both intralayer and\ninterlayer Coulomb interaction parameters. The solution of the excitonic gap\nparameter is used to calculate the electronic band structure, single-particle\nspectral functions, the hybridization gap, and the excitonic coherence length\nin the bilayer graphene. We show that the local interlayer Coulomb interaction\nis responsible for the semimetal-semiconductor transition in the double layer\nsystem, and we calculate the hybridization gap in the band structure above the\ncritical interaction value. The formation of the excitonic band gap is reported\nas the threshold process and the momentum distribution functions have been\ncalculated numerically. We show that in the weak coupling limit the system is\ngoverned by the Bardeen-Cooper-Schrieffer (BCS)-like pairing state. Contrary,\nin the strong coupling limit the excitonic condensate states appear in the\nsemiconducting phase, by forming the Dirac's pockets in the reciprocal space."
    },
    {
        "anchor": "Majorana Bound States in Double Nanowires with Reduced Zeeman Thresholds\n  due to Supercurrents: We study the topological phase diagram of a setup composed of two nanowires\nwith strong Rashba spin-orbit interaction subjected to an external magnetic\nfield and brought into the proximity to a bulk $s$-wave superconductor in the\npresence of a supercurrent flowing through it. The supercurrent reduces the\ncritical values of the Zeeman energy and crossed Andreev superconducting\npairing required to reach the topological phase characterized by the presence\nof one Majorana bound state localized at each system end. We demonstrate that,\neven in the regime of the crossed Andreev pairing being smaller than the direct\nproximity pairing, a relatively weak magnetic field drives the system into the\ntopological phase due to the presence of the supercurrent.",
        "positive": "Nonrelativistic theory of electromagnetic forces on particles and\n  nanoprobes moving near a surface: Closed nonrelativistic (nonretarded) theory of conservative and dissipative\nelectromagnetic forces and heat exchange between moving particles (nanoprobes)\nand a surface (flat and cylindrical) is reviewed. The formalism is based on\nmethods of classical and fluctuating electrodynamics using minimum assumptions.\nThe spatial dispersion effects are introduced via the surface response\nfunctions. The theory allows to treat various problems related with dynamic\ninteractions of charged particles, dipole molecules, neutral atoms and\nnanoprobes in a unified manner. For the first time, a brief review of the\nrecently obtained consistent relativistic results is also given. The\ncorresponding formulae exactly reduce to the nonrelativistic ones in the limit\nApplications to experiments with the scanning probe microscopes, quartz crystal\nmicrobalance technique and transmission of particle beams in the near field of\nsurfaces (through nanochannels) are discussed."
    },
    {
        "anchor": "Time-evolution patterns of electrons in twisted bilayer graphene: We characterise the dynamics of electrons in twisted bilayer graphene by\nanalysing the time-evolution of electron waves in the atomic lattice. We\nperform simulations based on a kernel polynomial technique using Chebyshev\npolynomial; this method does not requires any diagonalisation of the system\nHamiltonian. Our simulations reveal that the inter-layer electronic coupling\ninduces the exchange of waves between the two graphene layers. This wave\ntransfer manifests as oscillations of the layer-integrated probability\ndensities as a function of time. For the bilayer case, it also causes a\ndifference in the wavefront dynamics compared to monolayer graphene. The\nintra-layer spreading of electron waves is irregular and progresses as a\ntwo-stage process. The first one characterised by a well-defined wavefront\noccurs in a short time | a wavefront forms instead during the second stage. The\nwavefront takes a hexagon-like shape with the vertices developing faster than\nthe edges. Though the detail spreading form of waves depends on initial states,\nwe observe localisation of waves in specific regions of the moir\\'e zone. To\ncharacterise the electron dynamics, we also analyse the time auto-correlation\nfunctions. We show that these quantities shall exhibit the beating modulation\nwhen reducing the interlayer coupling.",
        "positive": "Measurement of magnetization using domain compressibility in CoFeB films\n  with perpendicular anisotropy: We present a method to map the saturation magnetization of soft ultrathin\nfilms with perpendicular anisotropy, and we illustrate it to assess the\ncompositional dependence of the magnetization of CoFeB(1 nm)/MgO films. The\nmethod relies on the measurement of the dipolar repulsion of parallel domain\nwalls that define a linear domain. The film magnetization is linked to the\nfield compressibility of the domain. The method also yields the minimal\ndistance between two walls before their merging, which sets a practical limit\nto the storage density in spintronic devices using domain walls as storage\nentities."
    },
    {
        "anchor": "Angular Momentum Conservation and Phonon Spin in Magnetic Insulators: We develop a microscopic theory of spin-lattice interactions in magnetic\ninsulators, separating rigid-body rotations and the internal angular momentum,\nor spin, of the phonons, while conserving the total angular momentum. In the\nlow-energy limit, the microscopic couplings are mapped onto experimentally\naccessible magnetoelastic constants. We show that the transient phonon spin\ncontribution of the excited system can dominate over the magnon spin, leading\nto nontrivial Einstein-de Haas physics.",
        "positive": "Phonon thermal conduction in novel 2D materials: Recently, there have been increasing interests in phonon thermal transport in\nlow dimensional materials, due to the crucial importance for dissipating and\nmanaging heat in micro and nano electronic devices. Significant progresses have\nbeen achieved for one-dimensional (1D) systems both theoretically and\nexperimentally. However, the study of heat conduction in two-dimensional (2D)\nsystems is still in its infancy due to the limited availability of 2D materials\nand the technical challenges in fabricating suspended samples suitable for\nthermal measurements. In this review, we outline different experimental\ntechniques and theoretical approaches for phonon thermal transport in 2D\nmaterials, discuss the problems and challenges in phonon thermal transport\nmeasurements and provide comparison between existing experimental data. Special\nfocus will be given to the effects of the size, dimensionality, anisotropy and\nmode contributions in the novel 2D systems including graphene, boron nitride,\nMoS2, black phosphorous, silicene etc."
    },
    {
        "anchor": "From kinetic to collective behavior in thermal transport on\n  semiconductors and semiconductor nanostructures: We present a model which deepens into the role that normal scattering has on\nthe thermal conductivity in semiconductor bulk, micro and nanoscale samples.\nThermal conductivity as a function of the temperature undergoes a smooth\ntransition from a kinetic to a collective regime that depends on the importance\nof normal scattering events. We demonstrate that in this transition, the key\npoint to fit experimental data is changing the way to perform the average on\nthe scattering rates. We apply the model to bulk Si with different isotopic\ncompositions obtaining an accurate fit. Then we calculate the thermal\nconductivity of Si thin films and nanowires by only introducing the effective\nsize as additional parameter. The model provides a better prediction of the\nthermal conductivity behavior valid for all temperatures and sizes above 30 nm\nwith a single expression. Avoiding the introduction of confinement or quantum\neffects, the model permits to establish the limit of classical theories in the\nstudy of the thermal conductivity in nanoscopic systems.",
        "positive": "Decay dynamics of quantum dots influenced by the local density of\n  optical states of two-dimensional photonic crystal membranes: We have performed time-resolved spectroscopy on InAs quantum dot ensembles in\nphotonic crystal membranes. The influence of the photonic crystal is\ninvestigated by varying the lattice constant systematically. We observe a\nstrong slow down of the quantum dots' spontaneous emission rates as the\ntwo-dimensional bandgap is tuned through their emission frequencies. The\nmeasured band edges are in full agreement with theoretical predictions. We\ncharacterize the multi-exponential decay curves by their mean decay time and\nfind enhancement of the spontaneous emission at the bandgap edges and strong\ninhibition inside the bandgap in good agreement with local density of states\ncalculations."
    },
    {
        "anchor": "Cation mono- and co-doped anatase TiO$_2$ nanotubes: An {\\em ab initio}\n  investigation of electronic and optical properties: The structural, electronic, and optical properties of metal (Si, Ge, Sn, and\nPb) mono- and co-doped anatase TiO$_{2}$ nanotubes are investigated, in order\nto elucidate their potential for photocatalytic applications. It is found that\nSi doped TiO$_{2}$ nanotubes are more stable than those doped with Ge, Sn, or\nPb. All dopants lower the band gap, except the (Ge, Sn) co-doped structure, the\ndecrease depending on the concentration and the type of dopant.\nCorrespondingly, a redshift in the optical properties for all kinds of dopings\nis obtained. Even though a Pb mono- and co-doped TiO$_{2}$ nanotube has the\nlowest band gap, these systems are not suitable for water splitting, due to the\nlocation of the conduction band edges, in contrast to Si, Ge, and Sn mono-doped\nTiO$_{2}$ nanotubes. On the other hand, co-doping of TiO$_{2}$ does not improve\nits photocatalytic properties. Our findings are consistent with recent\nexperiments which show an enhancement of light absorption for Si and Sn doped\nTiO$_{2}$ nanotubes.",
        "positive": "1/4 is the new 1/2 when topology is intertwined with Mottness: In non-interacting systems, bands from non-trivial topology emerge strictly\nat half-filling and exhibit either the quantum anomalous Hall or spin Hall\neffects. Here we show using determinantal quantum Monte Carlo and an exactly\nsolvable strongly interacting model that these topological states now shift to\nquarter filling. A topological Mott insulator is the underlying cause. The peak\nin the spin susceptibility is consistent with a possible ferromagnetic state at\n$T=0$. The onset of such magnetism would convert the quantum spin Hall to a\nquantum anomalous Hall effect. While such a symmetry-broken phase typically is\naccompanied by a gap, we find that the interaction strength must exceed a\ncritical value for this to occur. Hence, we predict that topology can obtain in\na gapless phase but only in the presence of interactions in dispersive bands.\nThese results explain the recent quarter-filled quantum anomalous Hall effects\nseen in moire systems."
    },
    {
        "anchor": "Temperature effect on the magnetic oscillations in 2D materials: We study the magnetic oscillations (MO) in 2D materials with a buckled\nhoneycomb lattice, considering a perpendicular electric and magnetic field. At\nzero temperature the MO consist of the sum of four sawtooth oscillations, with\ntwo unique frequencies and phases. The values of these frequencies depend on\nthe Fermi energy and electric field, which in turn determine the condition for\na beating phenomenon in the MO. We analyse the temperature effect in the MO by\nconsidering its local corrections over each magnetization peak, given by\nFermi-Dirac like functions. We show that the width of these functions is\nrelated to the minimum temperature necessary to observe the spin and valley\nproperties in the MO. In particular, we find that in order to observe the spin\nsplitting, the width must be lower than the MO phase difference. Likewise, in\norder to observe valley mixing effects, the width must be lower than the MO\nperiod. We also show that at high temperatures, all the maxima and minima in\nthe MO are shift to a constant value, in which case we obtain a simple\nexpression for the MO and its envelope. The results obtained show unique\nfeatures in the MO in 2D materials, given by the interplay between the valley\nand spin.",
        "positive": "Paired composite fermion wavefunctions: We construct a family of BCS paired composite fermion wavefunctions that\ngeneralize, but remain in the same topological phase as, the Moore-Read\nPfaffian state for the half-filled Landau level. It is shown that for a wide\nrange of experimentally relevant inter-electron interactions the groundstate\ncan be very accurately represented in this form."
    },
    {
        "anchor": "Non-linear conductance in mesoscopic weakly disordered wires --\n  Interaction and magnetic field asymmetry: We study the non-linear conductance $\\mathcal{G}\\sim\\partial^2I/\\partial\nV^2|_{V=0}$ in coherent quasi-1D weakly disordered metallic wires. The analysis\nis based on the calculation of two fundamental correlators (correlations of\nconductance's functional derivatives and correlations of injectivities), which\nare obtained explicitly by using diagrammatic techniques. In a coherent wire of\nlength $L$, we obtain $\\mathcal{G}\\sim0.006\\,E_\\mathrm{Th}^{-1}$ (and\n$\\langle\\mathcal{G}\\rangle=0$), where $E_\\mathrm{Th}=D/L^2$ is the Thouless\nenergy and $D$ the diffusion constant; the small dimensionless factor results\nfrom screening, i.e. cannot be obtained within a simple theory for\nnon-interacting electrons. Electronic interactions are also responsible for an\nasymmetry under magnetic field reversal: the antisymmetric part of the\nnon-linear conductance (at high magnetic field) being much smaller than the\nsymmetric one, $\\mathcal{G}_a\\sim0.001\\,(gE_\\mathrm{Th})^{-1}$, where $g\\gg1$\nis the dimensionless (linear) conductance of the wire. Weakly coherent regimes\nare also studied: for $L_\\varphi\\ll L$, where $L_\\varphi$ is the phase\ncoherence length, we get\n$\\mathcal{G}\\sim(L_\\varphi/L)^{7/2}E_\\mathrm{Th}^{-1}$, and\n$\\mathcal{G}_a\\sim(L_\\varphi/L)^{11/2}(gE_\\mathrm{Th})^{-1}\\ll\\mathcal{G}$ (at\nhigh magnetic field). When thermal fluctuations are important, $L_T\\ll\nL_\\varphi\\ll L$ where $L_T=\\sqrt{D/T}$, we obtain\n$\\mathcal{G}\\sim(L_T/L)(L_\\varphi/L)^{7/2}E_\\mathrm{Th}^{-1}$ (the result is\ndominated by the effect of screening) and\n$\\mathcal{G}_a\\sim(L_T/L)^2(L_\\varphi/L)^{7/2}(gE_\\mathrm{Th})^{-1}$. All the\nprecise dimensionless prefactors are obtained. Crossovers towards the zero\nmagnetic field regime are also analysed.",
        "positive": "Fractional quantum Hall effect and insulating phase of Dirac electrons\n  in graphene: In graphene, which is an atomic layer of crystalline carbon, two of the\ndistinguishing properties of the material are the charge carriers\ntwo-dimensional and relativistic character. The first experimental evidence of\nthe two-dimensional nature of graphene came from the observation of a sequence\nof plateaus in measurements of its transport properties in the presence of an\napplied magnetic field. These are signatures of the so-called integer quantum\nHall effect. However, as a consequence of the relativistic character of the\ncharge carriers, the integer quantum Hall effect observed in graphene is\nqualitatively different from its semiconductor analogue. As a third\ndistinguishing feature of graphene, it has been conjectured that interactions\nand correlations should be important in this material, but surprisingly,\nevidence of collective behaviour in graphene is lacking. In particular, the\nquintessential collective quantum behaviour in two dimensions, the fractional\nquantum Hall effect (FQHE), has so far resisted observation in graphene despite\nintense efforts and theoretical predictions of its existence. Here we report\nthe observation of the FQHE in graphene. Our observations are made possible by\nusing suspended graphene devices probed by two-terminal charge transport\nmeasurements. This allows us to isolate the sample from substrate-induced\nperturbations that usually obscure the effects of interactions in this system\nand to avoid effects of finite geometry. At low carrier density, we find a\nfield-induced transition to an insulator that competes with the FQHE, allowing\nits observation only in the highest quality samples. We believe that these\nresults will open the door to the physics of FQHE and other collective\nbehaviour in graphene."
    },
    {
        "anchor": "Self-excited current oscillations in a resonant tunneling diode\n  described by a model based on the Caldeira-Leggett Hamiltonian: The quantum dissipative dynamics of a tunneling process through double\nbarrier structures is investigated on the basis of non-perturbative and\nnon-Markovian treatment. We employ a Caldeira-Leggett Hamiltonian with an\neffective potential calculated self-consistently, accounting for the electron\ndistribution. With this Hamiltonian, we use the reduced hierarchy equations of\nmotion in the Wigner space representation to study non-Markovian and\nnon-perturbative thermal effects at finite temperature in a rigorous manner. We\nstudy current variation in time and the current-voltage (I-V) relation of the\nresonant tunneling diode for several widths of the contact region, which\nconsists of doped GaAs. Hysteresis and both single and double plateau-like\nbehavior are observed in the negative differential resistance (NDR) region.\nWhile all of the current oscillations decay in time in the NDR region in the\ncase of a strong system-bath coupling, there exist self-excited high-frequency\ncurrent oscillations in some parts of the plateau in the NDR region in the case\nof weak coupling. We find that the effective potential in the oscillating case\npossesses a basin-like form on the emitter side (emitter basin) and that the\ncurrent oscillation results from tunneling between the emitter basin and the\nquantum well in the barriers. We find two distinct types of current\noscillations, with large and small oscillation amplitudes, respectively. These\ntwo types of oscillation appear differently in the Wigner space, with one\nexhibiting tornado-like motion and the other exhibiting a two piston\nengine-like motion.",
        "positive": "Disorder and localization effects on the local spectroscopic and\n  infrared-optical properties of $\\mbox{Ga}_{1-x}\\mbox{Mn}_x\\mbox{As}$: We study numerically the influence of disorder and localization effects on\nthe local spectroscopic characteristics and infrared optical properties of\n$\\mbox{Ga}_{1-x}\\mbox{Mn}_x\\mbox{As}$. We treat the band structure and disorder\neffects at an equal level by using exact diagonalization supercell simulation\nmethod. This method accurately describes the low doping limit and gives a clear\npicture of the transition to higher dopings, which captures the localization\neffects inaccessible to other theoretical methods commonly used. Our\nsimulations capture the rich mid-gap localized states observed in scanning\ntunneling microscopy studies and reproduce the observed features of the\ninfrared optical absorption experiments. We show clear evidence of a disordered\nvalence band model for metallic samples in which (i) there is no impurity band\ndetached from the valence band, (ii) the disorder tends to localize and pull\nstates near the top of the valence band into the gap region, and (iii) the\nFermi energy is located deep in the delocalized region away from the mobility\nedge. We identify localized states deep in the gap region by visualizing the\nprobability distribution of the quasiparticles and connecting it to their\nrespective participation ratios. The analysis of the infrared-optical\nabsorption data indicates that it does not have a direct relation to the nature\nof the states at the Fermi energy."
    },
    {
        "anchor": "Effects of Microwave Absorption on Long and Short Single-Walled Carbon\n  Nanotubes at 10-6 Torr: Carbon nanotubes have been observed to emit ultraviolet, visible and infrared\nradiation when exposed to microwaves. We have performed experiments in which\nboth short (0.5 microns to 2 microns) and long (5 microns to 30 microns) single\nand double walled carbon nanotubes were exposed to 2.46 GHz microwaves at a\npressure of 10^-6 Torr. Structural modifications of the-carbon nanotubes due to\nmicrowave absorption have been studied using the Raman spectroscopy G-band and\nD-band intensities, which suggest that microwave irradiation at relatively low\npressure results in an increase in nanotube defects, especially in the case of\nthe long nanotubes. Furthermore, a comparison of the spectra of the radiation\nemitted from the nanotubes suggests that the longer nanotubes emitted radiation\nof much greater intensity than the shorter nanotubes. Based on the results of\nthe experiments and results described in previous reports, the ultraviolet,\nvisible and infrared radiation emitted as the result of microwave absorption by\ncarbon nanotubes seems to be primarily blackbody radiation emitted due to Joule\nheating. However, the presence of several broad photopeaks in the spectra of\nthe emitted radiation (which do not seem to be related to gases absorbed by the\nnanotubes or the presence of catalyst particles) suggest that emissions are not\nthe result of Joule heating alone.",
        "positive": "Protocols for optimal readout of qubits using a continuous quantum\n  nondemolition measurement: We study how the spontaneous relaxation of a qubit affects a continuous\nquantum non-demolition measurement of the initial state of the qubit. Given\nsome noisy measurement record $\\Psi$, we seek an estimate of whether the qubit\nwas initially in the ground or excited state. We investigate four different\nmeasurement protocols, three of which use a linear filter (with different\nweighting factors) and a fourth which uses a full non-linear filter that gives\nthe theoretically optimal estimate of the initial state of the qubit. We find\nthat relaxation of the qubit at rate $1/T_1$ strongly influences the fidelity\nof any measurement protocol. To avoid errors due to this decay, the measurement\nmust be completed in a time that decrease linearly with the desired fidelity\nwhile maintaining an adequate signal to noise ratio. We find that for the\nnon-linear filter the predicted fidelity, as expected, is always better than\nthe linear filters and that the fidelity is a monotone increasing function of\nthe measurement time. For example, to achieve a fidelity of 90%, the box car\nlinear filter requires a signal to noise ratio of $\\sim 30$ in a time $T_1$\nwhereas the non-linear filter only requires a signal to noise ratio of $\\sim\n18$."
    },
    {
        "anchor": "Solid-state circuit for spin entanglement generation and purification: We show how realistic charge manipulation and measurement techniques,\ncombined with the exchange interaction, allow for the robust generation and\npurification of four-particle spin entangled states in electrically controlled\nsemiconductor quantum dots. The generated states are immunized to the dominant\nsources of noise via a dynamical decoherence-free subspace; all additional\nerrors are corrected by a purification protocol. This approach may find\napplication in quantum computation, communication, and metrology.",
        "positive": "Spin diffusion length associated to out-of-plane resistivity of Pt thin\n  films in spin pumping experiments: We present a broadband ferromagnetic resonance study of the Gilbert damping\nenhancement ($\\Delta \\alpha$) due to spin pumping in NiFe/Pt bilayers. The\nbilayers, which have negligible interfacial spin memory loss, are studied as a\nfunction of the Pt layer thickness ($t_{\\text{Pt}}$) and temperature (100-293\nK). Within the framework of diffusive spin pumping theory, we demonstrate that\nDyakonov-Perel (DP) or Elliot-Yaffet (EY) spin relaxation mechanisms acting\nalone are incompatible with our observations. In contrast, if we consider that\nthe relation between spin relaxation characteristic time ($\\tau_{\\text{s}}$)\nand momentum relaxation characteristic time ($\\tau_{\\text{p}}$) is determined\nby a superposition of DP and EY mechanisms, the qualitative and quantitative\nagreement with experimental results is excellent. Remarkably, we found that\n$\\tau_{\\text{p}}$ must be determined by the out-of-plane electrical resistivity\n($\\rho$) of the Pt film and hence its spin diffusion length\n($\\lambda_{\\text{Pt}}$) is independent of $t_{\\text{Pt}}$. Our work settles the\ncontroversy regarding the $t_{\\text{Pt}}$ dependence of $\\lambda_{\\text{Pt}}$\nby demonstrating its fundamental connection with $\\rho$ considered along the\nsame direction of spin current flow. \\end{abstract}"
    },
    {
        "anchor": "Topological origin of quantized transport in non-Hermitian Floquet\n  chains: We show that non-Hermiticity enables topological phases with unidirectional\ntransport in one-dimensional Floquet chains. The topological signatures of\nthese phases are non-contractible loops in the spectrum of the Floquet\npropagator that are separated by an imaginary gap. Such loops occur exclusively\nin non-Hermitian Floquet systems. We define the corresponding topological\ninvariant as the winding number of the Floquet propagator relative to the\nimaginary gap. To relate topology to transport, we introduce the concept of\nregularized dynamics of non-Hermitian chains. We establish that, under the\nconditions of regularized dynamics, transport is quantized in so far as the\ncharge transferred over one period equals the topological winding number. We\nillustrate these theoretical findings with the example of a Floquet chain that\nfeatures a topological phase transition and acts as a charge pump in the\nnon-trivial topological phase. We finally discuss whether these findings\njustify the notion that non-Hermitian Floquet chains support topological\ntransport.",
        "positive": "Space-time gradient metasurfaces: Metasurfaces characterized by a transverse gradient of local impedance have\nrecently opened exciting directions for light manipulation at the nanoscale.\nHere we add a temporal gradient to the picture, showing that spatio-temporal\nvariations over a surface may largely extend the degree of light manipulation\nin metasurfaces, and break several of their constraints associated to\nsymmetries. As an example, we synthesize a non-reciprocal classical analogue to\nelectromagnetic induced transparency, opening a narrow window of one-way\ntransmission in an otherwise opaque surface. These properties pave the way to\nmagnetic free, planarized non-reciprocal ultrathin surfaces for free-space\nisolation."
    },
    {
        "anchor": "Effect of fermionic components on trion-electron scattering: To test the validity of replacing a composite fermion by an elementary\nfermion, we here calculate the transition rate from a state made of one free\nelectron and one trion to a similar electron-trion pair, through the time\nevolution of such a pair induced by Coulomb interaction between elementary\nfermions. To do it in a convenient way, we describe the trion as one electron\ninteracting with one exciton, and we use the tools we have developed in the new\ncomposite-exciton many-body theory. The trion-electron scattering contains a\ndirect channel in which ``in'' and ``out'' trions are made with the same\nfermions, and an exchange channel in which the ``in'' free electron becomes one\nof the ``out'' trion components. As expected, momenta are conserved in these\ntwo channels. The direct scattering is found to read as the bare Coulomb\npotential between elementary particles multiplied by a form factor which\ndepends on the ``in'' and ``out'' trion relative motion indices $\\eta$ and\n$\\eta'$, this factor reducing to $\\delta_{\\eta\\eta'}$ in the zero momentum\ntransfer limit: In this direct channel, the trion at large distance reacts as\nan elementary particle, its composite nature showing up for large momentum\ntransfer. On the contrary, the fact that the trion is not elementary does\naffect the exchange channel for all momentum transfers. We thus conclude that a\n3-component fermion behaves as an elementary fermion for direct processes in\nthe small momentum transfer limit only.",
        "positive": "Entanglement Spectrum Classification of $C_n$-invariant Noninteracting\n  Topological Insulators in Two Dimensions: We study the single particle entanglement spectrum in 2D topological\ninsulators which possess $n$-fold rotation symmetry. By defining a series of\nspecial choices of subsystems on which the entanglement is calculated, or real\nspace cuts, we find that the number of protected in-gap states for each type of\nthese real space cuts is a quantum number indexing (if any) non-trivial\ntopology in these insulators. We explicitly show the number of protected in-gap\nstates is determined by a $Z^n$-index, $(z_1,...,z_n)$, where $z_m$ is the\nnumber of occupied states that transform according to $m$-th one-dimensional\nrepresentation of the $C_n$ point group. We find that the entanglement spectrum\ncontains in-gap states pinned in an interval of entanglement eigenvalues\n$[1/n,1-1/n]$. We determine the number of such in-gap states for an exhaustive\nvariety of cuts, in terms of the $Z_m$ quantum numbers. Furthermore, we show\nthat in a homogeneous system, the $Z^n$ index can be determined through an\nevaluation of the eigenvalues of point group symmetry operators at all\nhigh-symmetry points in the Brillouin zone. When disordered $n$-fold\nrotationally symmetric systems are considered, we find that the number of\nprotected in-gap states is identical to that in the clean limit as long as the\ndisorder preserves the underlying point group symmetry and does not close the\nbulk insulating gap."
    },
    {
        "anchor": "Time- and Spectrally-Resolved PL Study of a Regular Array of\n  InP/InAs/InP Core-multishell Nanowires: Time- and spectrally-resolved PL from a periodic array of InP/InAs/InP\ncore-multishell nanowires is presented. InAs layer shows multipeak PL spectra.\nPL decay is nonexponential and very slow, with decay rate depending on energy.",
        "positive": "Comment on \"Quasi-One-Dimensional Metal-Insulator Transitions in\n  Compound Semiconductor Surfaces\": In a recent Letter, Zhao et al. [1] reported the origin of\nquasi-one-dimensional metal-insulator (MI) transitions in compound\nsemiconductor surfaces. Based on a density-functional theory (DFT) calculation\nwithin the generalized gradient approximation (GGA), they claimed that\none-atom-wide metallic structures formed by a selective bonding of H or Li\natoms to GaN(10-10) and ZnO(10-10) undergo the Peierls-type MI transitions,\nleading to a charge-density-wave (CDW) formation with periodic lattice\ndistortion. However, we here demonstrate that such a CDW phase is due to the\nartifact of the GGA, while the antiferromagnetic (AFM) ground state is\npredicted by the hybrid DFT calculation and the exact-exchange plus correlation\nin the random-phase approximation (EX + cRPA).\n  [1] J. Z. Zhao, W. Fan, M. J. Verstraete, Z. Zanolli, J. Fan, X. B. Yang, H.\nXu, and S. Y. Tong, Phys. Rev. Lett. 117, 116101 (2016)."
    },
    {
        "anchor": "I-V curve signatures of nonequilibrium-driven band gap collapse in\n  magnetically ordered zigzag graphene nanoribbon two-terminal devices: Motivated by the very recent fabrication of sub-10-nm-wide semiconducting\ngraphene nanoribbons [X. Li et al., Science 319, 1229 (2008)], whose band gaps\nextracted from transport measurements were fitted to density functional theory\npredictions for magnetic ordering along zigzag edges that is responsible for\nthe insulating ground state, we compute current-voltage (I-V) characteristics\nof finite-length zigzag graphene nanoribbons (ZGNR) attached to metallic\ncontacts. The transport properties of such devices, at source-drain bias\nvoltages beyond the linear response regime, are obtained using the\nnonequilibrium Green function formalism combined with the mean-field version of\nthe Hubbard model fitted to reproduce the local spin density approximation\ndescription of magnetic ordering. Our results indicate that magnetic ordering\nand the corresponding band gap in ZGNR can be completely eliminated by passing\nlarge enough DC current through it. The threshold voltage increases with the\nZGNR length (e.g., reaching $\\approx 0.8$ V for $\\simeq 13$ nm long ZGNR) which\nprovides possible explanation of why the recent experiments [Wang et al., Phys.\nRev. Lett. 100, 206803 (2008)] on $\\sim 100$ nm long GNR field-effect\ntransistors with bias voltage less than 1 V did not detect the I-V curve\nsignatures of the band gap collapse. Thus, observation of predicted abrupt jump\nin the I-V curve of two-terminal devices with short ZGNR channel and\ntransparent contacts will confirm its zigzag edge magnetic ordering via\nall-electrical measurements, as well as a current-flow-driven\nmagnetic-insulator--nonmagnetic-metal nonequilibrium phase transition.",
        "positive": "Time Reversal Symmetric Topological Exciton Condensate in Bilayer HgTe\n  Quantum Wells: We investigate a bilayer system of critical HgTe quantum wells each featuring\na spin-degenerate pair of massless Dirac fermions. In the presence of an\nelectrostatic inter-layer Coulomb coupling, we determine the exciton condensate\norder parameter of the system self-consistently. Calculating the bulk\ntopological $\\mathbb Z_2$ invariant of the resulting mean field Hamiltonian, we\ndiscover a novel time reversal symmetric topological exciton condensate state\ncoined the helical topological exciton condensate. We argue that this phase can\nexist for experimentally relevant parameters. Interestingly, due to its\nmulti-band nature, the present bilayer model exhibits a nontrivial interplay\nbetween spontaneous symmetry breaking and topology: Depending on which symmetry\nthe condensate order parameter spontaneously picks in combined orbital and spin\nspace, stable minima in the free energy corresponding to both trivial and\nnontrivial gapped states can be found."
    },
    {
        "anchor": "Exact results for nonlinear ac-transport through a resonant level model: We obtain exact results for the transport through a resonant level model\n(noninteracting Anderson impurity model) for rectangular voltage bias as a\nfunction of time. We study both the transient behavior after switching on the\ntunneling at time t = 0 and the ensuing steady state behavior. Explicit\nexpressions are obtained for the ac-current in the linear response regime and\nbeyond for large voltage bias. Among other effects, we observe current ringing\nand PAT (photon assisted tunneling) oscillations.",
        "positive": "Luminescence Spectra of Quantum Dots in Microcavities. I. Bosons: We provide a unified theory of luminescence spectra of coupled light-matter\nsystems realized with semiconductor heterostructures in microcavities,\nencompassing: i) the spontaneous emission case, where the system decays from a\nprepared (typically pure) initial state, and ii) luminescence in the presence\nof a continuous, incoherent pump. While the former case has been amply\ndiscussed in the literature (albeit mainly for the case of resonance), no\nconsideration has been given to the influence of the incoherent pump. We show\nhow, by provoking a self-consistent quantum state, the pump considerably alters\nthe emission spectra, even at vanishing intensities. The main outcome of our\nanalysis is to unambiguously identify strong-coupling in situations where it\nappears in disguise or only seems to appear. Here, we consider bosonic matter\nfields, in which case fully analytical solutions can be obtained. This\ndescribes the case of quantum wells or large quantum dots, or the limit of low\nexcitation where the average populations remain much smaller than one."
    },
    {
        "anchor": "Second harmonic generation spectroscopy of excitons in ZnO: Nonlinear optics of semiconductors is an important field of fundamental and\napplied research, but surprisingly the role of excitons in the coherent\nprocesses leading to harmonics generation has remained essentially unexplored.\nHere we report results of a comprehensive experimental and theoretical study of\nthe three-photon process of optical second harmonic generation (SHG) involving\nthe exciton resonances of the noncentrosymmetric hexagonal wide-band-gap\nsemiconductor ZnO in the photon energy range of 3.2-3.5 eV. Resonant\ncrystallographic SHG is observed for the 1s(A,B), 2s(A,B), 2p(A,B), and 1s(C)\nexcitons. We show that strong SHG signals at these exciton resonances are\ninduced by the application of a magnetic field when the incident and the SHG\nlight wave vectors are along the crystal z-axis where the crystallographic SHG\nresponse vanishes. A microscopic theory of SHG generation through excitons is\ndeveloped, which shows that the nonlinear interaction of coherent light with\nexcitons has to be considered beyond the electric-dipole approximation.\nDepending on the particular symmetry of the exciton states SHG can originate\nfrom the electric- and magnetic-field-induced perturbations of the excitons due\nto the Stark effect, the spin as well as orbital Zeeman effects, or the\nmagneto-Stark effect. The importance of each mechanism is analyzed and\ndiscussed by confronting experimental data and theoretical results for the\ndependencies of the SHG signals on photon energy, magnetic field, electric\nfield, crystal temperature, and light polarization. Good agreement is obtained\nbetween experiment and theory proving the validity of our approach to the\ncomplex problem of nonlinear interaction of light with ZnO excitons. This\ngeneral approach can be applied also to other semiconductors.",
        "positive": "Metamorphosis and Taxonomy of Andreev Bound States: We analyze the spatial and energy dependence of the local density of states\nin a SNS junction. We model our system as a one-dimensional tight-binding chain\nwhich we solve exactly by numerical diagonalization. We calculate the\ndependence of the Andreev bound states on position, phase difference, gate\nvoltage, and coupling with the superconducting leads. Our results confirm the\nphysics predicted by certain analytical approximations, but reveal a much\nricher set of phenomena beyond the grasp of these approximations, such as the\nmetamorphosis of the discrete states of the normal link (the normal bound\nstates) into Andreev bound states as the leads become superconducting."
    },
    {
        "anchor": "Excitation transport in quantum devices: analytical time-dependent\n  non-equilibrium green function algorithm: This research demonstrates analytical time-dependent non-equilibrium green\nfunction (TD-NEGF) algorithms to investigate dynamical functionalities of\nquantum devices, especially for photon-assisted transports. Together with the\nlumped element model, we also study the effects of transiently-transferring\ncharges to reflect the non-conservation of charges in open quantum systems, and\nimplement numerical calculations in hetero-junction systems composed of\nfunctional quantum devices and electrode-contacts (to the environment). The\nresults show that (i) the current calculation by the analytical algorithms,\nversus those by conventional numerical integrals, presents superior numerical\nstability on a large-time scale, (ii) the correction of charge transfer effects\ncan better clarify non-physical transport issues, e.g. the blocking of AC\nsignaling under the assumption of constant device charges, (iii) the current in\nthe long-time limit validly converges to the steady value obtained by standard\ntime-independent density functional calculations, and (iv) the occurrence of\nthe photon-assisted transport is well-identified.",
        "positive": "An On-Demand Single-Electron Time-Bin Qubit Source: We propose a source capable of on-demand emission of single electrons with a\nwave packet of controllable shape and phase. The source consists of a hybrid\nquantum system, relying on currently experimentally accessible components. We\nanalyze in detail the emission of single electron time-bin qubits, which we\ncharacterize using the well known electronic Hong-Ou-Mandel (HOM)\ninterferometry scheme. Specifically, we show that, by controlling the phase\ndifference of two time-bin qubits, the Pauli peak, the electronic analogue of\nthe well known optical HOM dip, can be continuously removed. The proposed\nsource constitutes a promising approach for scalable solid-state architectures\nfor quantum operations using electrons and possibly for an interface for photon\nto electron time-bin qubit conversion."
    },
    {
        "anchor": "Spin-orbit induced anisotropy in the tunneling magnetoresistance of\n  magnetic tunnel junctions: The effects of the spin-orbit interaction on the tunneling magnetoresistance\nof magnetic tunnel junctions are investigated. A model in which the\nexperimentally observed two-fold symmetry of the anisotropic tunneling\nmagnetoresistance (TAMR) originates from the interference between Dresselhaus\nand Bychkov-Rashba spin-orbit couplings is formulated. Bias induced changes of\nthe Bychkov-Rashba spin-orbit coupling strength can result in an inversion of\nthe TAMR. The theoretical calculations are in good agreement with the TAMR\nexperimentally observed in epitaxial Fe/GaAs/Au tunnel junctions.",
        "positive": "Voltage-tunable giant nonvolatile multiple-state resistance in\n  sliding-interlayer ferroelectric h-BN van der Waals multiferroic tunnel\n  junction: Multiferroic tunnel junctions (MFTJs) based on two-dimensional (2D) van der\nWaals heterostructures with sharp and clean interfaces at the atomic scale are\ncrucial for applications in nanoscale multi-resistive logic memory devices. The\nrecently discovered sliding ferroelectricity in 2D van der Waals materials has\nopened new avenues for ferroelectric-based devices. Here, we theoretically\ninvestigate the spin-dependent electronic transport properties of\nFe$_3$GeTe$_2$/graphene/bilayer-$h$-BN/graphene/CrI$_3$ (FGT/Gr-BBN-Gr/CrI)\nall-vdW MFTJs by employing the nonequilibrium Green's function combined with\ndensity functional theory. We demonstrate that such FGT/Gr-BBN-Gr/CrI MFTJs\nexhibit four non-volatile resistance states associated with different staking\norders of sliding ferroelectric BBN and magnetization alignment of\nferromagnetic free layer CrI$_3$, with a maximum tunnel magnetoresistance\n(electroresistance) ratio, i.e., TMR (TER) up to $\\sim$$3.36\\times10^{4}$\\%\n($\\sim$$6.68\\times10^{3}$\\%) at a specific bias voltage. Furthermore, the\nperfect spin filtering and remarkable negative differential resistance effects\nare evident in our MFTJs. We further discover that the TMR, TER, and spin\npolarization ratio under an equilibrium state can be enhanced by the\napplication of in-plane biaxial strain. This work shows that the giant\ntunneling resistance ratio, multiple resistance states, and excellent\nspin-polarized transport properties of sliding ferroelectric BBN-based MFTJs\nindicate its significant potential in nonvolatile memories."
    },
    {
        "anchor": "Charge detection in a bilayer graphene quantum dot: We show measurements on a bilayer graphene quantum dot with an integrated\ncharge detector. The focus lies on enabling charge detection with a 30 nm wide\nbilayer graphene nanoribbon located approximately 35 nm next to a bilayer\ngraphene quantum dot with an island diameter of about 100 nm. Local resonances\nin the nanoribbon can be successfully used to detect individual charging events\nin the dot even in regimes where the quantum dot Coulomb peaks cannot be\nmeasured by conventional techniques.",
        "positive": "A new regime of nanoscale thermal transport: collective diffusion\n  counteracts dissipation inefficiency: Understanding thermal transport from nanoscale heat sources is important for\na fundamental description of energy flow in materials, as well as for many\ntechnological applications including thermal management in nanoelectronics,\nthermoelectric devices, nano-enhanced photovoltaics and nanoparticle-mediated\nthermal therapies. Thermal transport at the nanoscale is fundamentally\ndifferent from that at the macroscale and is determined by the distribution of\ncarrier mean free paths in a material, the length scales of the heat sources,\nand the distance over which heat is transported. Past work has shown that\nFourier's law for heat conduction dramatically over-predicts the rate of heat\ndissipation from heat sources with dimensions smaller than the mean free path\nof the dominant heat-carrying phonons. In this work, we uncover a new regime of\nnanoscale thermal transport that dominates when the separation between\nnanoscale heat sources is small compared with the dominant phonon mean free\npaths. Surprisingly, the interplay between neighboring heat sources can\nfacilitate efficient, diffusive-like heat dissipation, even from the smallest\nnanoscale heat sources. This finding suggests that thermal management in\nnanoscale systems including integrated circuits might not be as challenging as\nprojected. Finally, we demonstrate a unique and new capability to extract mean\nfree path distributions of phonons in materials, allowing the first\nexperimental validation of differential conductivity predictions from\nfirst-principles calculations."
    },
    {
        "anchor": "Buckling-induced quadratic nonlinearity in silicon phonon waveguide\n  structures: We fabricated and characterized a single-crystal silicon phonon waveguide\nstructure with lead zirconate titanate (PZT) piezoelectric transducers. The\ncompressive stress in a silicon-on-insulator wafer causes a membrane waveguide\nto buckle, leading to the quadratic nonlinearity. The PZT transducer integrated\nin an on-chip configuration enables us to excite high-intensity mechanical\nvibration, which allows the characterization of nonlinear behavior. We observed\na softening nonlinear response as a function of the drive power and\ndemonstrated the mode shift and frequency conversion. This is the first report\nof the nonlinear behavior caused by the quadratic nonlinearity in a buckled\nphonon waveguide structure. This study provides a method to control the sign\nand the order of nonlinearity in a phonon waveguide by utilizing the internal\nstress, which allows the precise manipulation of elastic waves in phononic\nintegrated circuits.",
        "positive": "Distinction of Nuclear Spin States with the Scanning Tunneling\n  Microscope: We demonstrate rotational excitation spectroscopy with the scanning tunneling\nmicroscope for physisorbed hydrogen and its isotopes hydrogen-deuterid and\ndeuterium. The observed excitation energies are very close to the gas phase\nvalues and show the expected scaling with moment of inertia. Since these\nenergies are characteristic for the molecular nuclear spin states we are able\nto identify the para and ortho species of hydrogen and deuterium, respectively.\nWe thereby demonstrate nuclear spin sensitivity with unprecedented spatial\nresolution."
    },
    {
        "anchor": "An Electromagnetic Approach to Cavity Spintronics: The fields of cavity quantum electrodynamics and magnetism have recently\nmerged into \\textit{`cavity spintronics'}, investigating a quasiparticle that\nemerges from the strong coupling between standing electromagnetic waves\nconfined in a microwave cavity resonator and the quanta of spin waves, magnons.\nThis phenomenon is now expected to be employed in a variety of devices for\napplications ranging from quantum communication to dark matter detection. To be\nsuccessful, most of these applications require a vast control of the coupling\nstrength, resulting in intensive efforts to understanding coupling by a variety\nof different approaches. Here, the electromagnetic properties of both resonator\nand magnetic samples are investigated to provide a comprehensive understanding\nof the coupling between these two systems. Because the coupling is a\nconsequence of the excitation vector fields, which directly interact with\nmagnetisation dynamics, a highly-accurate electromagnetic perturbation theory\nis employed which allows for predicting the resonant hybrid mode frequencies\nfor any field configuration within the cavity resonator, without any fitting\nparameters. The coupling is shown to be strongly dependent not only on the\nexcitation vector fields and sample's magnetic properties but also on the\nsample's shape. These findings are illustrated by applying the theoretical\nframework to two distinct experiments: a magnetic sphere placed in a\nthree-dimensional resonator, and a rectangular, magnetic prism placed on a\ntwo-dimensional resonator. The theory provides comprehensive understanding of\nthe overall behaviour of strongly coupled systems and it can be easily modified\nfor a variety of other systems.",
        "positive": "Electrostatically confined Quantum Rings in bilayer Graphene: We propose a new system where electron and hole states are electrostatically\nconfined into a quantum ring in bilayer graphene. These structures can be\ncreated by tuning the gap of the graphene bilayer using nanostructured gates or\nby position-dependent doping. The energy levels have a magnetic field ($B_{0}$)\ndependence that is strikingly distinct from that of usual semiconductor quantum\nrings. In particular, the eigenvalues are not invariant under a $B_0 \\to -B_0$\ntransformation and, for a fixed total angular momentum index $m$, their field\ndependence is not parabolic, but displays two minima separated by a saddle\npoint. The spectra also display several anti-crossings, which arise due to the\noverlap of gate-confined and magnetically-confined states."
    },
    {
        "anchor": "Noise Analysis of Qubits Implemented in Triple Quantum Dot Systems in a\n  Davies Master Equation Approach: We analyze the influence of noise for qubits implemented using a triple\nquantum dot spin system. We give a detailed description of the physical\nrealization and develop error models for the dominant external noise sources.\nWe use a Davies master equation approach to describe their influence on the\nqubit. The triple dot system contains two meaningful realizations of a qubit:\nWe consider a subspace and a subsystem of the full Hilbert space to implement\nthe qubit. We test the robustness of these two implementations with respect to\nthe qubit stability. When performing the noise analysis, we extract the initial\ntime evolution of the qubit using a Nakajima-Zwanzig approach. We find that the\ninitial time evolution, which is essential for qubit applications, decouples\nfrom the long time dynamics of the system. We extract probabilities for the\nqubit errors of dephasing, relaxation and leakage. Using the Davies model to\ndescribe the environment simplifies the noise analysis. It allows us to\nconstruct simple toy models, which closely describe the error probabilities.",
        "positive": "Tunable Dirac points in a two-dimensional non-symmorphic wallpaper group\n  lattice: Non-symmorphic symmetries protect Dirac nodal lines and cones in lattice\nsystems. Here, we investigate the spectral properties of a two-dimensional\nlattice belonging to a non-symmorphic group. Specifically, we look at the\nherringbone lattice, characterised by two sets of glide symmetries applied in\ntwo orthogonal directions. We describe the system using a nearest-neighbour\ntight-binding model containing horizontal and vertical hopping terms. We find\ntwo non-equivalent Dirac cones inside the first Brillouin zone along a\nhigh-symmetry path. We tune these Dirac cones' positions by breaking the\nlattice symmetries using onsite potentials. These Dirac cones can merge into a\nsemi-Dirac cone or unfold along a high-symmetry path. Finally, we perturb the\nsystem by applying a dimerization of the hopping terms. We report a flow of\nDirac cones inside the first Brillouin zone describing quasi-hyperbolic curves.\nWe present an implementation in terms of CO atoms placed on the top of a\nCu(111) surface."
    },
    {
        "anchor": "Phonon Spectroscopy by Electric Measurements of Coupled Quantum Dots: We propose phonon spectroscopy by electric measurements of the\nlow-temperature conductance of coupled-quantum dots, specifically employing\ndephasing of the quantum electronic transport by the phonons. The setup we\nconsider consists of a T-shaped double-quantum-dot (DQD) system in which only\none of the dots (dot 1) is connected to external leads and the other (dot 2) is\ncoupled solely to the first one. For noninteracting electrons, the differential\nconductance of such a system vanishes at a voltage located in-between the\nenergies of the bonding and the anti-bonding states, due to destructive\ninterference. When electron-phonon (e-ph) on the DQD is invoked, we find that,\nat low temperatures, phonon emission taking place on dot 1 does not affect the\ninterference, while phonon emission from dot 2 suppresses it. The amount of\nthis suppression, as a function of the bias voltage, follows the effective e-ph\ncoupling reflecting the phonon density of states and can be used for phonon\nspectroscopy.",
        "positive": "Geometrical Nonlinearity of Circular Plates and Membranes: an\n  Alternative Method: We apply the well-established theoretical method developed for geometrical\nnonlinearities of micro/nano-mechanical clamped beams to circular drums. The\ncalculation is performed under the same hypotheses, the extra difficulty being\nto analytically describe the (coordinate-dependent) additional stress generated\nin the structure by the motion. Specifically, the model applies to\nnon-axisymmetric mode shapes. An analytic expression is produced for the\nDuffing (hardening) nonlinear coefficient, which requires only the knowledge of\nthe mode shape functions to be evaluated. This formulation is simple to handle,\nand does not rely on complex numerical methods. Moreover, no hypotheses are\nmade on the drive scheme and the nature of the in-plane stress: it is not\nrequired to be of electrostatic origin. We confront our predictions with both\ntypical experimental devices and relevant theoretical results from the\nliterature. Generalization of the presented method to Duffing-type\nmode-coupling should be a straightforward extension of this work. We believe\nthat the presented modeling will contribute to the development of nonlinear\nphysics implemented in 2D micro/nano-mechanical structures."
    },
    {
        "anchor": "Terahertz Plasmonic Detector Controlled by Phase Asymmetry: We demonstrate that phase-difference between terahertz signals on the source\nand drain of a field effect transistor (a TeraFET) induces a plasmon-assisted\ndc current, which is dramatically enhanced in vicinity of plasmonic resonances.\nWe describe a TeraFET operation with identical amplitudes of radiation on\nsource and drain antennas but with a phase-shift-induced asymmetry. In this\nregime, the TeraFET operates as a tunable resonant polarization-sensitive\nplasmonic spectrometer operating in the sub-terahertz and terahertz range of\nfrequencies. We also propose an effective scheme of a phase-sensitive homodyne\ndetector operating in a phase-asymmetry mode, which allows for a dramatic\nenhancement of the response. These regimes can be implemented in different\nmaterials systems including silicon. The p-diamond TeraFETs could support\noperation in the 200 to 600 GHz atmospheric windows.",
        "positive": "A physical realization of the quantum superalgebra sl_q(2/1): The article has been withdrawn by the author."
    },
    {
        "anchor": "Noise feedback in an electronic circuit: Electronic circuits are built by combining components with known\ncurrent/voltage characteristics, which are intrinsic to each component and\nindependent of the rest of the circuit. This approach breaks down for\nnanostructures placed at ultra-low temperature, a phenomenon referred to as\nDynamical Coulomb Blockade, and usually attributed to quantum effects. Here we\nreport similar phenomena on a simple circuit at room temperature, devoid of any\nquantum features: an avalanche diode in series with a resistor, where the\ncurrent/voltage characteristics of the diode depends strongly on the value of\nthe resistor. We show that the key ingredient for this is the feedback of the\nnoise of the component on itself through the rest of the circuit. Moreover, we\nhave developed a theory that links transport and noise in the presence of an\nexternal electromagnetic environment, which explains very well our experimental\nresults.",
        "positive": "Spectral Properties and Local Density of States of Disordered Quantum\n  Hall Systems with Rashba Spin-Orbit Coupling: We theoretically investigate the spectral properties and the spatial\ndependence of the local density of states (LDoS) in disordered two-dimensional\nelectron gases (2DEG) in the quantum Hall regime, taking into account the\ncombined presence of electrostatic disorder, random Rashba spin-orbit in-\nteraction, and finite Zeeman coupling. To this purpose, we extend a\ncoherent-state Green's function formalism previously proposed for spinless 2DEG\nin the presence of smooth arbitrary disorder, that here incorporates the\nnontrivial coupling between the orbital and spin degrees of freedom into the\nelectronic drift states. The formalism allows us to obtain analytical and\ncontrolled nonperturbative expressions of the energy spectrum in arbitrary\nlocally flat disorder potentials with both random electric fields and Rashba\ncoupling. As an illustration of this theory, we derive analytical microscopic\nexpressions for the LDoS in different temperature regimes which can be used as\na starting point to interpret scanning tunneling spectroscopy data at high\nmagnetic fields. In this context, we study the spatial dependence and linewidth\nof the LDoS peaks and explain an experimentally-noticed correlation between the\nspatial dispersion of the spin-orbit splitting and the local extrema of the\npotential landscape."
    },
    {
        "anchor": "Second Thresholds in BEC-BCS-Laser Crossover of Exciton-Polariton\n  Systems: The mechanism of second thresholds observed in several experiments is\ntheoretically revealed by studying the BEC-BCS-laser crossover in\nexciton-polariton systems. We found that there are two different types for the\nsecond thresholds; one is a crossover within quasi-equilibrium phases and the\nother is into non-equilibrium (lasing). In both cases, the light-induced band\nrenormalization causes gaps in the conduction and valence bands, which\nindicates the exsistence of bound electron-hole pairs in contrast to earlier\nexpectations. We also show that these two types can be distinguished by the\ngain spectra.",
        "positive": "Allowed and forbidden transitions in artificial hydrogen and helium\n  atoms: The strength of radiative transitions in atoms is governed by selection\nrules. Spectroscopic studies of allowed transitions in hydrogen and helium\nprovided crucial evidence for the Bohr's model of an atom. Forbidden\ntransitions, which are actually allowed by higher-order processes or other\nmechanisms, indicate how well the quantum numbers describe the system. We apply\nthese tests to the quantum states in semiconductor quantum dots (QDs), which\nare regarded as artificial atoms. Electrons in a QD occupy quantized states in\nthe same manner as electrons in real atoms. However, unlike real atoms, the\nconfinement potential of the QD is anisotropic, and the electrons can easily\ncouple with phonons of the material. Understanding the selection rules for such\nQDs is an important issue for the manipulation of quantum states. Here we\ninvestigate allowed and forbidden transitions for phonon emission in one- and\ntwo-electron QDs (artificial hydrogen and helium atoms) by electrical\npump-and-probe experiments, and find that the total spin is an excellent\nquantum number in artificial atoms. This is attractive for potential\napplications to spin based information storage."
    },
    {
        "anchor": "Observation of directly interacting coherent two-level systems in a\n  solid: Parasitic two-level tunneling systems originating from structural material\ndefects affect the functionality of various microfabricated devices by acting\nas a source of noise. In particular, superconducting quantum bits may be\nsensitive to even single defects when these reside in the tunnel barrier of the\nqubit's Josephson junctions, and this can be exploited to observe and\nmanipulate the quantum states of individual tunneling systems.\n  Here, we detect and fully characterize a system of two strongly interacting\ndefects using a novel technique for high-resolution spectroscopy. Mutual defect\ncoupling has been conjectured to explain various anomalies of glasses, and was\nrecently suggested as the origin of low frequency noise in superconducting\ndevices. Our study provides conclusive evidence of defect interactions with\nfull access to the individual constituents, demonstrating the potential of\nsuperconducting qubits for studying material defects. All our observations are\nconsistent with the assumption that defects are generated by atomic tunneling.",
        "positive": "Band structure and end states in InAs/GaSb core-shell-shell nanowires: Quantum wells in InAs/GaSb heterostructures can be tuned to a topological\nregime associated with the quantum spin Hall effect, which arises due to an\ninverted band gap and hybridized electron and hole states. Here, we investigate\nelectron-hole hybridization and the fate of the quantum spin Hall effect in a\nquasi one-dimensional geometry, realized in a core-shell-shell nanowire with an\ninsulator core and InAs and GaSb shells. We calculate the band structure for an\ninfinitely long nanowire using $\\mathbf{k \\cdot p}$ theory within the Kane\nmodel and the envelope function approximation, then map the result onto a BHZ\nmodel which is used to investigate finite-length wires. Clearly, quantum spin\nHall edge states cannot appear in the core-shell-shell nanowires which lack\none-dimensional edges, but in the inverted band-gap regime we find that the\nfinite-length wires instead host localized states at the wire ends. These end\nstates are not topologically protected, they are four-fold degenerate and split\ninto two Kramers pairs in the presence of potential disorder along the axial\ndirection. However, there is some remnant of the topological protection of the\nquantum spin Hall edge states in the sense that the end states are fully robust\nto (time-reversal preserving) angular disorder, as long as the bulk band gap is\nnot closed."
    },
    {
        "anchor": "Electron transport through a diatomic molecule: Electron transport through a diatomic molecular tunnel junction shows wave\nlike interference phenomenon. By using Keldysh non-equilibrium Green's function\n(NEGF) theory, we have explicitly presented current and differential\nconductance calculation for a diatomic molecular and two isolated atoms (two\natoms having zero hybridization between their energy orbital) tunnel junctions.\nIn case of a diatomic molecular tunnel junction, Green's function propagators\nentering into current and differential conductance formula interfere\nconstructively for a molecular anti-bonding state and destructively for bonding\nstate. Consequently, conductance through a molecular bonding state is\nsuppressed, and to conserve current, conductance through anti-bonding state is\nenhanced. Therefore, current steps and differential conductance peaks amplitude\nshow asymmetric correspondence between molecular bonding and anti-bonding\nstates. Interestingly, for a diatomic molecule, comprising of two atoms of same\nenergy level, these propagators interfere completely destructively for\nmolecular bonding state and constructively for molecular anti-bonding state.\nHence under such condition, a single step or a single peak is shown up in\ncurrent versus voltage or differential conductance versus voltage studies.",
        "positive": "Computation of intrinsic spin Hall conductivities from first principles\n  using maximally-localized Wannier functions: We present a method to compute the intrinsic spin Hall conductivity from\nfirst principles using an interpolation scheme based on maximally-localized\nWannier functions. After obtaining the relevant matrix elements among the ab\ninitio Bloch states calculated on a coarse k-point mesh, we Fourier transform\nthem to find the corresponding matrix elements between Wannier states. We then\nperform an inverse Fourier transform to interpolate the velocity and\nspin-current matrix elements onto a dense k-point mesh, and use them to\nevaluate the spin Hall conductivity as a Brillouin-zone integral. This strategy\nhas a much lower computational cost than a direct ab initio calculation,\nwithout sacrificing the accuracy. We demonstrate that the spin Hall\nconductivities of platinum and doped gallium arsenide, computed with our\ninterpolation scheme as a function of the Fermi energy, are in good agreement\nwith those obtained in previous first-principles studies. We also discuss\ncertain approximations that can be made, in the spirit of the tight-binding\nmethod, to simplify the calculation of the velocity and spin-current matrix\nelements in the Wannier representation."
    },
    {
        "anchor": "Coherent transport and manipulation of spins in indirect exciton\n  nanostructures: We report on the coherent control and transport of indirect exciton (IX)\nspins in GaAs double quantum well (DQW) nanostructures. The spin dynamics was\ninvestigated by optically generating spins using a focused, circularly\npolarized light spot and by probing their spatial distribution using spatially\nand polarization resolved photoluminescence spectroscopy. Optically injected\nexciton spins precess while diffusing over distances exceeding 20 {\\mu}m from\nthe excitation spot with a spatial precession frequency that depends on the\nspin transport direction as well as on the bias applied across the DQW\nstructure. This behavior is attributed to the spin precession in the effective\nmagnetic field induced by the spin-orbit interaction. From the dependence of\nthe spin dynamics on the transport direction, bias and external magnetic fields\nwe directly determined the Dresselhaus and Rashba spin splitting coefficients\nfor the structure. The precession dynamics is essentially independent on the IX\ndensity, thus indicating that the long spin lifetimes are not associated with\nIX collective effects. The latter, together with the negligible contribution of\nholes to the spin dynamics, are rather attributed to spatial separation of the\nelectron and hole wave functions by the electric field, which reduces the\nelectron-hole exchange interaction. Coherent spin precession over long\ntransport distances as well as the control of the spin vector using electric\nand magnetic fields open the way for the application of IX spins in the quantum\ninformation processing.",
        "positive": "Andreev bound states versus Majorana bound states in quantum\n  dot-nanowire-superconductor hybrid structures: Trivial versus topological\n  zero-bias conductance peaks: Motivated by an important recent experiment [Deng et al., Science 354, 1557\n(2016)], we theoretically consider the interplay between Andreev bound\nstates(ABSs) and Majorana bound states(MBSs) in quantum dot-nanowire\nsemiconductor systems with proximity-induced superconductivity(SC), spin-orbit\ncoupling and Zeeman splitting. The dot induces ABSs in the SC nanowire which\nshow complex behavior as a function of Zeeman splitting and chemical potential,\nand the specific question is whether two such ABSs can come together forming a\ntopological MBS. We consider physical situations involving the dot being\nnon-SC, SC, or partially SC. We find that the ABSs indeed tend to coalesce\ntogether producing near-zero-energy midgap states as Zeeman splitting and/or\nchemical potential are increased, but this mostly happens in the\nnon-topological regime although there are situations where the ABSs could come\ntogether forming a topological MBS. The two scenarios(two ABSs forming a\nnear-zero-energy non-topological ABS or a zero-energy topological MBS) are\ndifficult to distinguish by tunneling conductance spectroscopy due to\nessentially the same signatures. Theoretically we distinguish them by knowing\nthe critical Zeeman splitting for the topological quantum phase transition or\nby calculating the topological visibility. We find that the \"sticking together\"\npropensity of ABSs to produce a zero-energy midgap state is generic in class D\nsystems, and by itself says nothing about the topological nature of the\nunderlying SC nanowire. One must use caution in interpreting tunneling\nconductance measurements where the midgap sticking-together behavior of ABSs\ncannot be construed as definitive evidence for topological SC with non-Abelian\nMBSs. We also suggest some experimental techniques for distinguishing between\ntrivial and topological ZBCPs."
    },
    {
        "anchor": "Analysis and Geometric Optimization of Single Electron Transistors for\n  Read-Out in Solid-State Quantum Computing: The single electron transistor (SET) offers unparalled opportunities as a\nnano-scale electrometer, capable of measuring sub-electron charge variations.\nSETs have been proposed for read-out schema in solid-state quantum computing\nwhere quantum information processing outcomes depend on the location of a\nsingle electron on nearby quantum dots. In this paper we investigate various\ngeometries of a SET in order to maximize the device's sensitivity to charge\ntransfer between quantum dots. Through the use of finite element modeling we\nmodel the materials and geometries of an Al/Al2O3 SET measuring the state of\nquantum dots in the Si substrate beneath. The investigation is motivated by the\nquest to build a scalable quantum computer, though the methodology used is\nprimarily that of circuit theory. As such we provide useful techniques for any\nelectronic device operating at the classical/quantum interface.",
        "positive": "Tunnel-Field-Effect Spin Filter from Two-Dimensional Antiferromagnetic\n  Stanene: We propose a device concept, based on monolayer stanene, able to provide\nhighly polarized spin currents (up to a $98\\%$) with voltage-controlled spin\npolarization operating at room temperature and with small operating voltage\n($0.3$ V). The concept exploits the presence of spin-polarized edge states in a\nstanene nanoribbon. The spin polarization of the total current can be modulated\nby a differential tuning of the transmission properties, and of the occupation\nof edge states of different spin, via the application of an in-plane electric\nfield. We demonstrate device operation using ab-initio and quantum transport\nsimulations."
    },
    {
        "anchor": "Dark and thermal reservoir contributions to polariton sound velocity: Exciton-polaritons in an optical microcavity can form a macroscopically\ncoherent state despite being an inherently driven-dissipative system. In\ncomparison with equilibrium bosonic fluids, polaritonic condensates possess\nmultiple peculiarities that make them behave differently from well-known\ntextbook examples. One such peculiarity is the presence of dark excitons which\nare created by the pump together with optically-active particles. They can\nconsiderably affect the spectrum of elementary excitations of the condensate\nand hence change its superfluid properties. Here, we theoretically analyze the\ninfluence of the bright and dark ``reservoir'' populations on the sound\nvelocity $c_s$ of incoherently-driven polaritons. Both pulsed and\ncontinuous-wave pumping schemes characterized by essentially different\ncondensate-to-reservoir ratio are considered. We show that the dark exciton\ncontribution leads to considerable lowering of $c_s$ and to its deviation from\nthe square-root-like behavior on the system's chemical potential (measurable\ncondensate blueshift). Importantly, our model allows to unambiguously define\nthe density of dark excitons in the system by experimentally tracking $c_s$\nagainst the condensate blueshift and fitting the dependence at a given\ntemperature.",
        "positive": "The density of states of chaotic Andreev billiards: Quantum cavities or dots have markedly different properties depending on\nwhether their classical counterparts are chaotic or not. Connecting a\nsuperconductor to such a cavity leads to notable proximity effects,\nparticularly the appearance, predicted by random matrix theory, of a hard gap\nin the excitation spectrum of quantum chaotic systems. Andreev billiards are\ninteresting examples of such structures built with superconductors connected to\na ballistic normal metal billiard since each time an electron hits the\nsuperconducting part it is retroreflected as a hole (and vice-versa). Using a\nsemiclassical framework for systems with chaotic dynamics, we show how this\nreflection, along with the interference due to subtle correlations between the\nclassical paths of electrons and holes inside the system, are ultimately\nresponsible for the gap formation. The treatment can be extended to include the\neffects of a symmetry breaking magnetic field in the normal part of the\nbilliard or an Andreev billiard connected to two phase shifted superconductors.\nTherefore we are able to see how these effects can remold and eventually\nsuppress the gap. Furthermore the semiclassical framework is able to cover the\neffect of a finite Ehrenfest time which also causes the gap to shrink. However\nfor intermediate values this leads to the appearance of a second hard gap - a\nclear signature of the Ehrenfest time."
    },
    {
        "anchor": "Fully Atomistic Molecular Dynamics Investigation of the Simplest Model\n  of Dry-Draw Fabrication of Carbon Nanotube Fibers: Macroscopic assemblies of carbon nanotubes (CNTs) are desirable materials\nbecause of the excellent CNT properties. Amongst the methods of production of\nthese CNT materials, the dry-draw fabrication where CNT fibers (CNTFs) are\ndirectly pulled out from a CNT forest is known to provide good physical\nproperties. Although it is known that vertical alignment of CNT bundles within\nthe CNT forest is important, the mechanisms behind the dry-draw fabrication of\nCNTFs are still not completely understood. The simplest known dry-draw model\nconsists of CNT bundles laterally interacting by only van der Waals forces\n(vdWf). Here, by fully atomistic classical molecular dynamics simulations, we\nshow that the simplest dry-draw model does not produce CNTFs. We also show one\nimportant condition for a pair of adjacent CNT bundles to connect themselves\nunder vdWf only and discuss why it leads to the failure of the simplest model.",
        "positive": "Maximal tripartite entanglement between singlet-triplet qubits in\n  quantum dots: Singlet-triplet states in double quantum dots are promising realizations of\nqubits, and capacitive coupling can be used to create entanglement between\nthese qubits. We propose an entangling three-qubit gate of singlet-triplet\nqubits in a triangular setup. Our simulations using a realistic microscopic\nmodel show that a maximally entangled Greenberger-Horne-Zeilinger state can be\ngenerated as the qubits are evolved under exchange. Furthermore, our analysis\nfor the gate operation can be used to extract the actual experimental pulse\nsequence needed to realize this."
    },
    {
        "anchor": "The Axion Insulator as a Pump of Fragile Topology: The axion insulator (AXI) has long been recognized as the simplest example of\na 3D magnetic topological insulator (TI). The most familiar AXI results from\nmagnetically gapping the surface states of a 3D $\\mathbb{Z}_{2}$ TI while\npreserving the bulk gap. Like the 3D TI, it exhibits a quantized\nmagnetoelectric polarizability of $\\theta=\\pi$, and can be diagnosed from bulk\nsymmetry eigenvalues when inversion symmetric. However, whereas a 3D TI is\ncharacterized by bulk Wilson loop winding, 2D surface states, and the pumping\nof the 2D $\\mathbb{Z}_{2}$ TI index, we show that an AXI with a large number of\nbulk bands displays no Wilson loop winding, exhibits chiral hinge states, and\ndoes not pump any previously identified quantity. Crucially, as the AXI\nexhibits the topological angle $\\theta=\\pi$, its occupied bands cannot be\nformed into maximally localized symmetric Wannier functions, despite its\nabsence of Wilson loop winding. In this letter, we revisit the AXI from the\nperspective of the recently introduced notion of \"fragile\" topology, and\ndiscover that it in fact can be generically expressed as the cyclic pumping of\na \"trivialized\" fragile phase: a 2D inversion-symmetric insulator with no\nWilson loop winding which nevertheless carries a nontrivial topological index,\nthe nested Berry phase $\\gamma_{2}$. We numerically show that the nontrivial\nvalue $\\gamma_{2}=\\pi$ indicates the presence of anomalous 0D corner charges in\na 2D insulator, and therefore, that the chiral pumping of $\\gamma_{2}$ in a 3D\nAXI corresponds to the presence of chiral hinge states. We also briefly\ngeneralize our results to time-reversal-symmetric higher-order TIs, and discuss\nthe related appearance of nontrivial $\\gamma_{2}$ protected by\n$C_{2}\\times\\mathcal{T}$ symmetry in twisted bilayer graphene, and its\nimplications for the presence of 0D corner states.",
        "positive": "Edge states, Majorana fermions and topological order in superconducting\n  wires with generalized boundary conditions: We study the properties of one-dimensional topological superconductors under\nthe influence of generic boundary conditions mimicking the coupling with\nexternal environments. We identify a general four-parameters classification of\nthe boundary effects and show that particle-hole and reflection symmetries can\nbe broken or preserved by appropriately fixing the boundary parameters. When\nthe particle-hole symmetry is broken, the topological protection of the edge\nmodes is lost due to the hybridization with the external degrees of freedom\n(quasiparticle poisoning). We assess the robustness of the edge modes in the\nvarious regimes by considering different quantifiers of topological properties.\nIn particular, we investigate the resilience of the long-distance, edge-to-edge\nquantum mutual information and squashed entanglement, measuring the nonlocal\ncorrelations of the Majorana excitations. Besides their relevance for the open\ndynamics of topological systems, these results may provide a useful guide to\nthe appropriate embedding of low-dimensional topological systems on nanodevices\nin realistic conditions."
    },
    {
        "anchor": "Magnetoresistance of compensated semimetals in confined geometries: Two-component conductors -- e.g., semi-metals and narrow band semiconductors\n-- often exhibit unusually strong magnetoresistance in a wide temperature\nrange. Suppression of the Hall voltage near charge neutrality in such systems\ngives rise to a strong quasiparticle drift in the direction perpendicular to\nthe electric current and magnetic field. This drift is responsible for a strong\ngeometrical increase of resistance even in weak magnetic fields. Combining the\nBoltzmann kinetic equation with sample electrostatics, we develop a microscopic\ntheory of magnetotransport in two and three spatial dimensions. The compensated\nHall effect in confined geometry is always accompanied by electron-hole\nrecombination near the sample edges and at large-scale inhomogeneities. As the\nresult, classical edge currents may dominate the resistance in the vicinity of\ncharge compensation. The effect leads to linear magnetoresistance in two\ndimensions in a broad range of parameters. In three dimensions, the\nmagnetoresistance is normally quadratic in the field, with the linear regime\nrestricted to rectangular samples with magnetic field directed perpendicular to\nthe sample surface. Finally, we discuss the effects of heat flow and\ntemperature inhomogeneities on the magnetoresistance.",
        "positive": "Non-abelian gauge fields and quadratic band touchings in molecular\n  graphene: Dirac fermions in graphene can be subjected to non-abelian gauge fields by\nimplementing certain modulations of the carbon site potentials. Artificial\ngraphene, engineered with a lattice of CO molecules on top of the surface of\nCu, offers an ideal arena to study their effects. In this work, we show by\nsymmetry arguments how the underlying CO lattice must be deformed to obtain\nthese gauge fields, and estimate their strength. We also discuss the\nfundamental differences between abelian and non-abelian gauge fields from the\nDirac electrons point of view, and show how a constant (non-abelian) magnetic\nfield gives rise to either a Landau level spectrum or a quadratic band\ntouching, depending on the gauge field that realizes it (a known feature of\nnon-abelian gauge fields known as the Wu-Yang ambiguity). We finally present\nthe characteristic signatures of these effects in the site-resolved density of\nstates that can be directly measured in the current molecular graphene\nexperiment, and discuss prospects to realize the interaction induced broken\nsymmetry states of a quadratic touching in this system."
    },
    {
        "anchor": "Domain-wall orientation in antiferromagnets controlled by magnetoelastic\n  effects: In this paper, we develop the mathematical framework to describe the physical\nphenomenon behind the equilibrium configuration joining two antiferromagnetic\ndomains. We firstly define the total energy of the system and deduce the\ngoverning equations by minimizing it with respect to the field variables. Then,\nwe solve the resulting system of nonlinear PDEs together with proper initial\nand boundary conditions by varying the orientation of the 90$^{\\circ}$ domain\nwall (DW) configuration along the sample. Finally, the angular dependence of\nelastic and magnetoelastic energies as well as of incompatibility-driven volume\neffects is computed.",
        "positive": "Thermoelectrics with Coulomb coupled quantum dots: In this article we review the thermoelectric properties of three terminal\ndevices with Coulomb coupled quantum dots (QDs) as observed in recent\nexperiments [1,2]. The system we consider consists of two Coulomb-blockade QDs\none of which can exchange electrons with only a single reservoir (heat\nreservoir) while the other dot is tunnel coupled to two reservoirs at a lower\ntemperature (conductor). The heat reservoir and the conductor interact only via\nthe Coulomb-coupling of the quantum dots. It has been found that two regimes\nhave to be considered. In the first one heat flow between the two systems is\nsmall. In this regime thermally driven occupation fluctuations of the hot QD\nmodify the transport properties of the conductor system. This leads to an\neffect called thermal gating. Experiment have shown how this can be used to\ncontrol charge flow in the conductor by means of temperature in a remote\nreservoir. We further substantiate the observations with model calculations and\nimplications for the realization of an all-thermal transistor are discussed. In\nthe second regime, heat flow between the two systems is relevant. Here the\nsystem works as a nano scale heat engine, as proposed recently [3]. We review\nthe conceptual idea, its experimental realization and the novel features\narising in this new kind of thermoelectric device such as decoupling of heat\nand charge flow."
    },
    {
        "anchor": "Plasmonics of coupled graphene micro-structures: The optical response of graphene micro-structures, such as micro-ribbons and\ndisks, is dominated by the localized plasmon resonance in the far infrared (IR)\nspectral range. An ensemble of such structures is usually involved and the\neffect of the coupling between the individual structures is expected to play an\nimportant role. In this paper, the plasmonic coupling of graphene\nmicrostructures in different configurations is investigated. While a relatively\nweak coupling between graphene disks on the same plane is observed, the\ncoupling between vertically stacked graphene disks is strong and a drastic\nincrease of the resonance frequency is demonstrated. The plasmons in a more\ncomplex structure can be treated as the hybridization of plasmons from more\nelementary structures. As an example, the plasmon resonances of graphene\nmicro-rings are presented, in conjunction with their response in a magnetic\nfield. Finally, the coupling of the plasmon and the surface polar phonons of\nSiO2 substrate is demonstrated by the observation of a new hybrid resonance\npeak around 500cm-1.",
        "positive": "Reorientation of Anisotropy in a Square Well Quantum Hall Sample: We have measured magnetotransport at half-filled high Landau levels in a\nquantum well with two occupied electric subbands. We find resistivities that\nare {\\em isotropic} in perpendicular magnetic field but become strongly {\\em\nanisotropic} at $\\nu$ = 9/2 and 11/2 on tilting the field. The anisotropy\nappears at an in-plane field, $B_{ip} \\sim$ 2.5T, with the easy-current\ndirection {\\em parallel} to $B_{ip}$ but rotates by 90$^{\\circ}$ at $B_{ip}\n\\sim$ 10T and points now in the same direction as in single-subband samples.\nThis complex behavior is in quantitative agreement with theoretical\ncalculations based on a unidirectional charge density wave state model."
    },
    {
        "anchor": "The $\u03bd=5/2$ Fractional Quantum Hall State in the Presence of Alloy\n  Disorder: We report quantitative measurements of the impact of alloy disorder on the\n$\\nu=5/2$ fractional quantum Hall state. Alloy disorder is controlled by the\naluminum content $x$ in the Al$_x$Ga$_{1-x}$As channel of a quantum well. We\nfind that the $\\nu=5/2$ state is suppressed with alloy scattering. To our\nsurprise, in samples with alloy disorder the $\\nu=5/2$ state appears at\nsignificantly reduced mobilities when compared to samples in which alloy\ndisorder is not the dominant scattering mechanism. Our results highlight the\ndistinct roles of the different types of disorder present in these samples,\nsuch as the short-range alloy and the long-range Coulomb disorder.",
        "positive": "Quantum mechanical complementarity probed in a closed-loop Aharonov-Bohm\n  interferometer: According to Bohr's complementarity principle, a particle possesses wave-like\nproperties only when the different paths the particle may take are\nindistinguishable. In a canonical example of a two-path interferometer with a\nwhich-path detector, observation of interference and obtaining which-path\ninformation are mutually exclusive. Such duality has been demonstrated in\noptics with a pair of correlated photons and in solid-state devices with\nphase-coherent electrons. In the latter case, which-path information was\nprovided by a charge detector embedded near one path of a two-path electron\ninterferometer. Note that suppression of interference can always be understood\neither as obtaining path information or as unavoidable back action by the\ndetector. The present study reports on dephasing of an Aharonov-Bohm (AB) ring\ninterferometer via a coupled charge detector adjacent to the ring. In contrast\nto the two-path interferometer, charge detection in the ring does not always\nprovide path information. Indeed, we found that the interference was suppressed\nonly when path information could be acquired, even if only in principle. This\ndemonstrates that dephasing does not always take place by coupling the\n`environment' to the interfering particle: path information of the particle\nmust be available too. Moreover, this is valid regardless of the strength of\nenvironment-interferometer coupling, which refutes the general notion of the\neffect of strong interaction with the environment. In other words, it verifies\nthat an acquisition of which-path information is more fundamental than the\nback-action in understanding quantum mechanical complementarity."
    },
    {
        "anchor": "Tuning the conductance of a molecular switch: The ability to control the conductance of single molecules will have a major\nimpact in nanoscale electronics. Azobenzene, a molecule that changes\nconformation as a result of a trans/cis transition when exposed to radiation,\ncould form the basis of a light-driven molecular switch. It is therefore\ncrucial to clarify the electrical transport characteristics of this molecule.\nHere, we investigate theoretically charge transport in a system in which a\nsingle azobenzene molecule is attached to two carbon nanotubes. In clear\ncontrast to gold electrodes, the nanotubes can act as true nanoscale electrodes\nand we show that the low-energy conduction properties of the junction may be\ndramatically modified by changing the topology of the contacts between the\nnanotubes and the molecules, and/or the chirality of the nanotubes (that is,\nzigzag or armchair). We propose experiments to demonstrate controlled\nelectrical switching with nanotube electrodes.",
        "positive": "Charge and spin current in a quasi-one-dimensional quantum wire with\n  spin-orbit coupling: We show that Rashba spin-orbit coupling may result in an energy gap in the\nspectrum of electrons in a two-mode quantum wire if a suitable confining\npotential is chosen. This leads to a dip in the conductance and a spike in the\nspin current at the corresponding position of the Fermi level. Therefore one\nmay control the charge and spin currents by means of electrostatic gates\nwithout using magnetic field or magnetic materials."
    },
    {
        "anchor": "In-situ Piezoresponse Force Microscopy Cantilever Mode Shape Profiling: The frequency-dependent amplitude and phase in piezoresponse force microscopy\n(PFM) measurements are shown to be a consequence of the Euler-Bernoulli (EB)\ndynamics of atomic force microscope (AFM) cantilever beams used to make the\nmeasurements. Changes in the cantilever mode shape as a function of changes in\nthe boundary conditions determine the sensitivity of cantilevers to forces\nbetween the tip and the sample. Conventional PFM and AFM measurements are made\nwith the motion of the cantilever measured at one optical beam detector (OBD)\nspot location. A single OBD spot location provides a limited picture of the\ntotal cantilever motion and in fact, experimentally observed cantilever\namplitude and phase are shown to be strongly dependent on the OBD spot position\nfor many measurements. In this work, the commonly observed frequency dependence\nof PFM response is explained through experimental measurements and analytic\ntheoretical EB modeling of the PFM response as a function of both frequency and\nOBD spot location on a periodically poled lithium niobate (PPLN) sample. One\nnotable conclusion is that a common choice of OBD spot location, at or near the\ntip of the cantilever is particularly vulnerable to frequency dependent\namplitude and phase variations stemming from dynamics of the cantilever sensor\nrather than from the piezoresponse of the sample.",
        "positive": "Engineering Nanowire n-MOSFETs at Lg < 8 nm: As metal-oxide-semiconductor field-effect transistors (MOSFET) channel\nlengths (Lg) are scaled to lengths shorter than Lg<8 nm source-drain tunneling\nstarts to become a major performance limiting factor. In this scenario a\nheavier transport mass can be used to limit source-drain (S-D) tunneling.\nTaking InAs and Si as examples, it is shown that different heavier transport\nmasses can be engineered using strain and crystal orientation engineering.\nFull-band extended device atomistic quantum transport simulations are performed\nfor nanowire MOSFETs at Lg<8 nm in both ballistic and incoherent scattering\nregimes. In conclusion, a heavier transport mass can indeed be advantageous in\nimproving ON state currents in ultra scaled nanowire MOSFETs."
    },
    {
        "anchor": "Anisotropic contribution to the van der Waals and the Casimir-Polder\n  energies for CO$_2$ and CH$_4$ molecules near surfaces and thin films: In order to understand why carbon dioxide (CO$_2$) and methane (CH$_4$)\nmolecules interact differently with surfaces, we investigate the Casimir-Polder\nenergy of a linearly polarizable CO$_2$ molecule and an isotropically\npolarizable CH$_4$ molecule in front of an atomically thin gold film and an\namorphous silica slab. We quantitatively analyze how the anisotropy in the\npolarizability of the molecule influences the van der Waals contribution to the\nbinding energy of the molecule.",
        "positive": "Enhanced Interfacial Dzyaloshinskii-Moriya Interaction in annealed\n  Pt/Co/MgO structures: The interfacial Dzyaloshinskii-Moriya interaction (iDMI) is attracting great\ninterests for spintronics. An iDMI constant larger than 3 mJ/m^2 is expected to\nminimize the size of skyrmions and to optimize the DW dynamics. In this study,\nwe experimentally demonstrate an enhanced iDMI in Pt/Co/X/MgO ultra-thin film\nstructures with perpendicular magnetization. The iDMI constants were measured\nusing a field-driven creep regime domain expansion method. The enhancement of\niDMI with an atomically thin insertion of Ta and Mg is comprehensively\nunderstood with the help of ab-initio calculations. Thermal annealing has been\nused to crystallize the MgO thin layer for improving tunneling\nmagneto-resistance (TMR), but interestingly it also provides a further increase\nof the iDMI constant. An increase of the iDMI constant up to 3.3 mJ/m^2 is\nshown, which could be promising for the scaling down of skyrmion electronics."
    },
    {
        "anchor": "Colossal nonreciprocal Hall effect and broadband frequency mixing due to\n  a room temperature nonlinear Hall effect: Nonreciprocal (NR) charge transport in quantum materials has attracted\nenormous interest since it offers an avenue to investigate quantum symmetry\nrelated physics and holds many prospective applications such as rectification\nand photodetection over a wide range of frequencies. The NR transport reported\nto date occurs along the longitudinal direction with the NR resistance limited\nto a few percent of the ohmic resistance. Here we report a transverse\nnonreciprocal transport phenomenon with divergent nonreciprocity - colossal NR\nHall effect. This is revealed in direct current (DC) measurements on the\nmicroscale Hall devices made of the Pt wires deposited by focused ion beam\n(FIB) on Si substrates and the Weyl semimetal NbP with FIB-deposited Pt\nelectrodes at 0 magnetic field. When a DC is applied along the x-axis of the\ndevices Ix, it generates a voltage along the y-axis Vy near room temperature,\nwith Vy quadratically scaling with Ix. The transverse resistance, which shows a\nsign reversal upon switching the current direction, results from a colossal\nextrinsic nonlinear Hall effect (NLHE) rooted in the disorder scatterings in\nthe Pt wires. While NbP was not found to show NLHE, the NLHE generated in the\nPt electrodes can be transmitted to the NbP Hall devices, which yields a\nsurprisingly large nonlinear anomalous Hall effect in NbP with the Hall angle\n(${\\Theta_H}$) far exceeding the record value of the anomalous Hall angle of\nmagnetic conductors at room temperature. Furthermore, we find such a strong\nNLHE can lead to broadband frequency mixing, with the frequency spectrum of the\nHall voltage including 2nd-harmonic generation, sum & difference frequency\ngenerations, and other multiple wave mixing components. These results not only\ndemonstrate the concept of the NRHE for the first time but also pave the way\nfor exploring NLHE's applications in Thz communication, imaging, and energy\nharvesting.",
        "positive": "Spin amplification, reading, and writing in transport through\n  anisotropic magnetic molecules: Inelastic transport through a single magnetic molecule weakly coupled to\nmetallic leads is studied theoretically. We consider dynamical processes that\nare relevant for writing, storing, and reading spin information in molecular\nmemory devices. Magnetic anisotropy is found to be crucial for slow spin\nrelaxation. In the presence of anisotropy we find giant spin amplification: The\nspin accumulated in the leads if a bias voltage is applied to a molecule\nprepared in a spin-polarized state can be made exponentially large in a\ncharacteristic energy divided by temperature. For one ferromagnetic and one\nparamagnetic lead the molecular spin can be reversed by applying a bias voltage\neven in the absence of a magnetic field. We propose schemes for reading and\nwriting spin information based on our findings."
    },
    {
        "anchor": "Plasmons in nanoscale metal junctions: optical rectification and\n  thermometry: We use simultaneous electronic transport and optical characterization\nmeasurements to reveal new information about electronic and optical processes\nin nanoscale junctions fabricated by electromigration. Comparing electronic\ntunneling and photocurrents allows us to infer the optical frequency potential\ndifference produced by the plasmon response of the junction. Together with the\nmeasured tunneling conductance, we can then determine the locally enhanced\nelectric field within the junction. In similar structures containing molecules,\nanti-Stokes and Stokes Raman emission allow us to infer the effective local\nvibrational and electronic temperatures as a function of DC current, examining\nheating and dissipation on the nanometer scale.",
        "positive": "On Anderson Localisation of Two-Dimensional Electrons in Weak Magnetic\n  Field: The two-parameter renormalization group flow diagramme is used for obtaining\nthe magnetic field dependence of localisation length Lc(B) for charged\nparticles in 2D random potential at low disorder and weak magnetic fields B.\nThe result reproduces the periodic singularities of Lc(B)."
    },
    {
        "anchor": "Massive Dirac fermions in moir\u00e9 superlattices: a route towards\n  topological flat minibands: We demonstrate a generic mechanism to realize topological flat minibands by\nconfining massive Dirac fermions in a periodic moir\\'e potential, which can be\nachieved in a heterobilayer of transition metal dichalcogenides. We show that\nthe topological phase can be protected by the symmetry of moir\\'e potential and\nsurvive to arbitrarily large Dirac band gap. We take the MoTe$_2$/WSe$_2$\nheterobilayer as an example and find that the topological phase can be driven\nby a vertical electric field. By projecting the Coulomb interaction onto the\ntopological fat minibands, we identify a correlated Chern insulator at half\nfilling and a quantum valley-spin Hall insulator at full filling which explains\nthe topological states observed in the MoTe$_2$/WSe$_2$ in experiment. Our work\nclarifies the importance of Dirac structure for the topological minibands and\nunveils a general strategy to design topological moir\\'e materials.",
        "positive": "Thermal transport in granular metals: We study the electron thermal transport in granular metals at large tunnel\nconductance between the grains, $g_T \\gg 1$ and not too low a temperature $T >\ng_T\\delta$, where $\\delta$ is the mean energy level spacing for a single grain.\nTaking into account the electron-electron interaction effects we calculate the\nthermal conductivity and show that the Wiedemann-Franz law is violated for\ngranular metals. We find that interaction effects suppress the thermal\nconductivity less than the electrical conductivity."
    },
    {
        "anchor": "Modulation induced transport signatures in correlated electron\n  waveguides: Recent transport experiments in spatially modulated quasi-1D structures\ncreated on top of LaAlO$_3$/SrTiO$_3$ interfaces have revealed some interesting\nfeatures, including phenomena conspicuously absent without the modulation. In\nthis work, we focus on two of these remarkable features and provide theoretical\nanalysis allowing their interpretation. The first one is the appearance of\ntwo-terminal conductance plateaus at rational fractions of $e^2/h$. We explain\nhow this phenomenon, previously believed to be possible only in systems with\nstrong repulsive interactions, can be stabilized in a system with attraction in\nthe presence of the modulation. Using our theoretical framework we find the\nplateau amplitude and shape, and characterize the correlated phase which\ndevelops in the system due to the partial gap, namely a Luttinger liquid of\nelectronic trions. The second observation is a sharp conductance dip below a\nconductance of $1\\times e^2/h$, which changes its value over a wide range when\ntuning the system. We theorize that it is due to resonant backscattering caused\nby a periodic spin-orbit field. The behavior of this dip can be reliably\naccounted for by considering the finite length of the electronic waveguides, as\nwell as the interactions therein. The phenomena discussed in this work\nexemplify the intricate interplay of strong interactions and spatial\nmodulations, and reveal the potential for novel strongly correlated phases of\nmatter in systems which prominently feature both.",
        "positive": "Strong Coupling of Two-Dimensional Excitons and Plasmonic Photonic\n  Crystals: Microscopic Theory Reveals Triplet Spectra: Monolayers of transition metal dichalcogenides (TMDC) are direct-gap\nsemiconductors with strong light-matter interactions featuring tightly bound\nexcitons, while plasmonic crystals (PCs), consisting of metal nanoparticles\nthat act as meta-atoms, exhibit collective plasmon modes and allow one to\ntailor electric fields on the nanoscale. Recent experiments show that TMDC-PC\nhybrids can reach the strong-coupling limit between excitons and plasmons\nforming new quasiparticles, so-called plexcitons. To describe this coupling\ntheoretically, we develop a self-consistent Maxwell-Bloch theory for TMDC-PC\nhybrid structures, which allows us to compute the scattered light in the near-\nand far-field explicitly and provide guidance for experimental studies. Our\ncalculations reveal a spectral splitting signature of strong coupling of more\nthan $100\\,$meV in gold-MoSe$_2$ structures with $30\\,$nm nanoparticles,\nmanifesting in a hybridization of exciton and plasmon into two effective\nplexcitonic bands. In addition to the hybridized states, we find a remaining\nexcitonic mode with significantly smaller coupling to the plasmonic near-field,\nemitting directly into the far-field. Thus, hybrid spectra in the strong\ncoupling regime can contain three emission peaks."
    },
    {
        "anchor": "Quadrupole Shift of Nuclear Magnetic Resonance of Donors in Silicon at\n  Low Magnetic Field: Shifts from the expected nuclear magnetic resonance frequencies of antimony\nand bismuth donors in silicon of greater than a megahertz are observed in\nelectrically detected magnetic resonance spectra. Defects created by ion\nimplantation of the donors are discussed as the source of effective electric\nfield gradients generating these shifts via quadrupole interaction with the\nnuclear spins. The experimental results are modeled quantitatively by molecular\norbital theory for a coupled pair consisting of a donor and a spin-dependent\nrecombination readout center.",
        "positive": "Nonadiabatic charge pumping across two superconductors connected through\n  a normal metal region by periodically driven potentials: Periodically driven systems exhibit resonance when the difference between an\nexcited state energy and the ground state energy is an integer multiple of\n$\\hbar$ times the driving frequency. On the other hand, when a superconducting\nphase difference is maintained between two superconductors, subgap states\nappear which carry a Josephson current. A driven Josephson junction therefore\nopens up an interesting avenue where the excitations due to applied driving\naffect the current flowing from one superconductor to the other. Motivated by\nthis, we study charge transport in a superconductor-normal metal-superconductor\n(SNS) junction where oscillating potentials are applied to the normal metal\nregion. We find that for small amplitudes of the oscillating potential, driving\nat one site reverses the direction of current at the superconducting phase\ndifferences when difference between the subgap eigenenergies of the undriven\nHamiltonian is integer multiple of $\\hbar$ times the driving frequency. For\nlarger amplitudes of oscillating potential, driving at one site exhibits richer\nfeatures. We show that even when the two superconductors are maintained at same\nsuperconducting phase, a current can be driven by applying oscillating\npotentials to two sites in the normal metal differing by a phase. We find that\nwhen there is a nonzero Josephson current in the undriven system, the local\npeaks and valleys in current of the system driven with an amplitude of\noscillating potential smaller than the superconducting gap indicates sharp\nexcitations in the system. In the adiabatic limit, we find that charge\ntransferred in one time period diverges as a powerlaw with pumping frequency\nwhen a Josephson current flows in the undriven system. Our calculations are\nexact and can be applied to finite systems. We discuss possible experimental\nsetups where our predictions can be tested."
    },
    {
        "anchor": "Fast magnetization reversal of nanoclusters in resonator: An effective method for ultrafast magnetization reversal of nanoclusters is\nsuggested. The method is based on coupling a nanocluster to a resonant electric\ncircuit. This coupling causes the appearance of a magnetic feedback field\nacting on the cluster, which drastically shortens the magnetization reversal\ntime. The influence of the resonator properties, nanocluster parameters, and\nexternal fields on the magnetization dynamics and reversal time is analyzed.\nThe magnetization reversal time can be made many orders shorter than the\nnatural relaxation time. The reversal is studied for both the cases of a single\nnanocluster as well as for the system of many nanoclusters interacting through\ndipole forces.",
        "positive": "Feshbach resonances of composite charge carrier states in atomically\n  thin semiconductor heterostructures: Feshbach resonances play a vital role in the success of cold atoms\ninvestigating strongly-correlated physics. The recent observation of their\nsolid-state analog in the scattering of holes and intralayer excitons in\ntransition metal dichalcogenides [Schwartz et al., Science 374, 336 (2021)]\nholds compelling promise for bringing fully controllable interactions to the\nfield of semiconductors. Here, we demonstrate how tunneling-induced layer\nhybridization can lead to the emergence of two distinct classes of Feshbach\nresonances in atomically thin semiconductors. Based on microscopic scattering\ntheory we show that these two types of Feshbach resonances allow to tune\ninteractions between electrons and both short-lived intralayer, as well as\nlong-lived interlayer excitons. We predict the exciton-electron scattering\nphase shift from first principles and show that the exciton-electron coupling\nis fully tunable from strong to vanishing interactions. The tunability of\ninteractions opens the avenue to explore Bose-Fermi mixtures in solid-state\nsystems in regimes that were previously only accessible in cold atom\nexperiments."
    },
    {
        "anchor": "Spin and Charge Pumping by Ferromagnetic-Superconductor Order Parameters: We study transport in ferromagnetic-superconductor/normal-metal systems. It\nis shown that charge and spin currents are pumped from ferromagnetic\nsuperconductors into adjacent normal metals by adiabatic changes in the order\nparameters induced by external electromagnetic fields. Spin and charge pumping\nidentify the symmetry of the superconducting order parameter, e.g., singlet\npairing or triplet pairing with opposite or equal spin pairing. Consequences\nfor ferromagnetic-resonance experiments are discussed.",
        "positive": "Role of Coulomb Interaction in Valley Photogalvanic Effect: We develop a theory of Coulomb interaction-related contribution to the\nphotogalvanic current of electrons in two-dimensional non-centrosymmetric Dirac\nmaterials possessing a nontrivial structure of valleys and exposed to an\nexternal electromagnetic field. The valley photogalvanic effect occurs here due\nto the trigonal warping of electrons and holes' dispersions in a given valley\nof the monolayer. We study the low-frequency limit of the external field: the\nfield frequency is smaller than the temperature $T$, and the electron-electron\nand electron-hole scattering times are much larger than the electron-impurity\nscattering time. In this regime, we employ the Boltzmann transport equations\nand show that electron-hole scattering dominates electron-electron scattering\nin intrinsic semiconductors. Coulomb interaction-related contribution to the\nvalley photogalvanic current can reduce the value of the bare photogalvanic\ncurrent as these two currents flow in opposite directions."
    },
    {
        "anchor": "Edge states and topological pumping in elastic lattices with\n  periodically modulated coupling: We investigate the dispersion topology of elastic lattices characterized by\nspatial stiffness modulation. The modulation is defined by the sampling of a\ntwo-dimensional surface, which provides the lattices with topological\nproperties that are usually attributed to two-dimensional crystals. We show\nthat the cyclic variation of the phase of the stiffness modulation leads to a\nBerry phase accumulation for the Bloch eigenmodes, which is characterized by\ninteger valued Chern numbers for the bands and associated gap labels. The\nresulting non-trivial gaps are spanned by edge modes localized at one of the\nboundaries of the considered 1D lattices. The edge mode location is governed by\nthe phase of the stiffness distribution, whose spatial modulation drives these\nmodes to transition from one edge to the other, through a bulk state that\noccurs when the corresponding dispersion branch touches the bulk bands. This\nproperty enables the implementation of a topological pump that is obtained by\nstacking and coupling a family of modulated 1D lattices along a second spatial\ndimension. The gradual variation of the stiffness phase modulation drives the\nadiabatic transition of the edge states, which transition from their localized\nstate at one boundary, to a bulk mode and, finally, to another localized state\nat the opposite boundary. Similar effects were illustrated under the assumption\nof quasiperiodic modulation of the lattice interactions. We here demonstrate\nthat a topological pump can be achieved also in periodic media, and illustrate\nthis for the first time in elastic discrete lattices.",
        "positive": "Quantized Hall current in topological nodal-line semimetal: Photocurrent acts as one of measurable responses of material to light, which\nhas proved itself to be crucial for sensing and energy harvesting. Topological\nsemimetals with gapless energy dispersion and abundant topological surface and\nbulk states exhibit exotic photocurrent responses, such as novel quantized\ncircular photogalvanic effect observed in Weyl semimetals. Here we find that\nfor a topological nodal-line semimetal (NLSM) with nodal ring bulk states and\ndrumhead surface states (DSS), a significant photocurrent can be produced by an\nelectromagnetic (EM) wave by means of the quantum Hall effect. The Hall current\nis enabled by electron transfer between Landau levels (LLs) and triggered by\nboth the electric field and magnetic field components of an EM wave. This Hall\ncurrent is physically connected to an unusually large quantum-Hall conductivity\nof the zeroth LLs resulting from quantized DSS. These LLs are found to be\nhighly degenerate due to the unique band-folding effect associated with\nmagnetic-field-induced expansion of a unit cell. Furthermore, we observe that\nthe Hall current induced solely by an in-plane linearly-polarized EM wave\nbecomes a quantized entity which allows for possible direct measurement of the\nDSS density in a topological NLSM. This work paves a way toward designing\nhigh-magnetic-field-sensitivity detection devices for industrial and space\napplications, such as the development of self-detection of\ncurrent-surge-induced overheating in electronic devices and accurate Earth's\nmagnetic-anomaly maps for guiding a self-navigating drone or an aircraft."
    },
    {
        "anchor": "Ultra-short suspended single-wall carbon nanotube transistors: We describe a method to fabricate clean suspended single-wall carbon nanotube\n(SWCNT) transistors hosting a single quantum dot ranging in length from a few\n10s of nm down to $\\approx$ 3 nm. We first align narrow gold bow-tie junctions\non top of individual SWCNTs and suspend the devices. We then use a\nfeedback-controlled electromigration to break the gold junctions and expose\nnm-sized sections of SWCNTs. We measure electron transport in these devices at\nlow temperature and show that they form clean and tunable single-electron\ntransistors. These ultra-short suspended transistors offer the prospect of\nstudying THz oscillators with strong electron-vibron coupling.",
        "positive": "Emergent flat band lattices in spatially periodic magnetic fields: Motivated by the recent discovery of Mott insulating phase and unconventional\nsuperconductivity due to the flat bands in twisted bilayer graphene, we propose\nmore generic ways of getting two-dimensional (2D) emergent flat band lattices\nusing either 2D Dirac materials or ordinary electron gas (2DEG) subject to\nmoderate periodic orbital magnetic fields with zero spatial average. Employing\nboth momentum-space and real-space numerical methods to solve the eigenvalue\nproblems, we find stark contrast between Schr\\\"{o}dinger and Dirac electrons,\ni.e., the former show recurring \"magic\" values of the magnetic field when the\nlowest band becomes flat, while for the latter the zero-energy bands are\nasymptotically flat without magicness. By examining the Wannier functions\nlocalized by the smooth periodic magnetic fields, we are able to explain these\nnontrivial behaviors using minimal tight-binding models on a square lattice.\nThe two cases can be interpolated by varying the $g$-factor or effective mass\nof a 2DEG and by taking into account the Zeeman coupling, which also leads to\nflat bands with nonzero Chern numbers for each spin. Our work provides flexible\nplatforms for exploring interaction-driven phases in 2D systems with on-demand\nsuperlattice symmetries."
    },
    {
        "anchor": "Dynamical amplification of magnetoresistances and Hall currents up to\n  the THz regime: Spin-orbit-related effects offer a highly promising route for reading and\nwriting information in magnetic units of future devices. These phenomena rely\nnot only on the static magnetization orientation but also on its dynamics to\nachieve fast switchings that can reach the THz range. In this work, we consider\nCo/Pt and Fe/W bilayers to show that accounting for the phase difference\nbetween different processes is crucial to the correct description of the\ndynamical currents. By tuning each system towards its ferromagnetic resonance,\nwe reveal that dynamical spin Hall angles can non-trivially change sign and be\nboosted by over 500%, reaching giant values. We demonstrate that charge and\nspin pumping mechanisms can greatly magnify or dwindle the currents flowing\nthrough the system, influencing all kinds of magnetoresistive and Hall effects,\nthus impacting also dc and second harmonic experimental measurements.",
        "positive": "Minigap and Andreev bound states in ballistic graphene: A finite-size normal conductor, proximity-coupled to a superconductor has\nbeen predicted to exhibit a so-called minigap, in which quasiparticle\nexcitations are prohibited. Here, we report on the direct observation of such a\nminigap in ballistic graphene, coupled to superconducting MoRe leads. The\nminigap is probed by finite bias spectroscopy through a weakly coupled junction\nin the graphene region and its value is given by the dimensions of the device.\nBesides the minigap, we observe a distinct peak in the differential resistance,\nwhich we attribute to weakly coupled Andreev bound states (ABS) located near\nthe superconductor-graphene interface. For weak magnetic fields, the phase\naccumulated in the normal-conducting region shifts the ABS in quantitative\nagreement with predictions from tight-binding calculations based on the\nBogolioubov-de Gennes equation as well as with an analytical semiclassical\nmodel."
    },
    {
        "anchor": "Linear and nonlinear transport across carbon nanotube quantum dots: We present a low energy-theory for non-linear transport in finite-size\ninteracting single-wall carbon nanotubes. It is based on a microscopic model\nfor the interacting p_z electrons and successive bosonization. We consider weak\ncoupling to the leads and derive equations of motion for the reduced density\nmatrix. We focus on the case of large-diameter nanotubes where exchange effects\ncan be neglected. In this situation the energy spectrum is highly degenerate.\nDue to the multiple degeneracy, diagonal as well as off-diagonal (coherences)\nelements of the density matrix contribute to the nonlinear transport. At low\nbias, a four-electron periodicity with a characteristic ratio between adjacent\npeaks is predicted. Our results are in quantitative agreement with recent\nexperiments.",
        "positive": "Intrinsic Limits of Subthreshold Slope in Biased Bilayer Graphene\n  Transistor: In this work, we investigate the intrinsic limits of subthreshold slope in a\ndual gated bilayer graphene transistor using a coupled self-consistent\nPoisson-bandstructure solver. We benchmark the solver by matching the bias\ndependent bandgap results obtained from the solver against published\nexperimental data. We show that the intrinsic bias dependence of the electronic\nstructure and the self-consistent electrostatics limit the subthreshold slope\nobtained in such a transistor well above the Boltzmann limit of 60mV/decade at\nroom temperature, but much below the results experimentally shown till date,\nindicating room for technological improvement of bilayer graphene."
    },
    {
        "anchor": "Van Hove scenario of anisotropic transport in a two-dimensional\n  spin-orbit coupled electron gas in an in-plane magnetic field: We study electronic transport in two-dimensional spin-orbit coupled electron\ngas subjected to an in-plane magnetic field. The interplay of the spin-orbit\ninteraction and the magnetic field leads to the Van Hove singularity of the\ndensity of states and strong anisotropy of Fermi contours. We develop a method\nthat allows one to exactly calculate the nonequilibrium distribution function\nfor these conditions within the framework of the semiclassical Boltzmann\nequation without using the scattering time approximation. The method is applied\nto calculate the conductivity tensor and the tensor of spin polarization\ninduced by the electric field (Aronov-Lyanda-Geller-Edelstein effect). It is\nfound that both the conductivity and the spin polarization have a sharp\nsingularity as functions of the Fermi level or magnetic field, which occurs\nwhen the Fermi level passes through the Van Hove singularity. In addition, the\ntransport anisotropy dramatically changes near the singularity.",
        "positive": "Quantum phenomena in the radial thermal expansion of bundles of\n  single-walled carbon nanotubes doped with 3He. A giant isotope effect: The radial thermal expansion {\\alpha}r of bundles of single-walled carbon\nnanotubes saturated with 3He up to the molar concentration 9.4% has been\ninvestigated in the temperature interval 2.1-9.5 K by high-sensitivity\ncapacitance dilatometry. In the interval 2.1-7 K a negative {\\alpha}r was\nobserved, with a magnitude which exceeded the largest negative {\\alpha}r values\nof pure and 4He-saturated nanotubes by three and two orders of magnitude,\nrespectively. The contributions of the two He isotope impurities to the\nnegative thermal expansion of the nanotube bundles are most likely connected\nwith the spatial redistribution of 4He and 3He atoms by tunneling at the\nsurface and inside nanotube bundles. The isotope effect turned out to be huge,\nprobably owing to the higher tunneling probability of 3He atoms."
    },
    {
        "anchor": "Vacuum anomalous Hall effect in gyrotropic cavity: We consider the ground state of an electron gas embedded in a quantum\ngyrotropic cavity. We show that the light-matter interaction leads to a\nnontrivial topology of the many-body electron-photon wave function\ncharacterized by a nonzero Berry curvature. Physically, the latter manifests as\nthe anomalous Hall effect, appearance of equilibrium edge/surface currents and\norbital magnetization induced by vacuum fluctuations. Remarkably, closed\nanalytical expressions for the anomalous Hall conductivity and macroscopic\nmagnetization are obtained for the interacting many-body case.",
        "positive": "Optical bistability of graphene in the terahertz range: We use an exact solution of the relaxation-time Boltzmann equation in a\nuniform AC electric field to describe the nonlinear optical response of\ngraphene in the terahertz (THz). The cases of monolayer, bilayer and\nABA-stacked trilayer graphene are considered, and the monolayer species is\nshown to be the most appropriate one to exploit the nonlinear free electron\nresponse. We find that a single layer of monolayer graphene shows an optical\nbistability in the THz range, within the electromagnetic power range attainable\nin practice. The current associated with the third harmonic generation is also\ncomputed."
    },
    {
        "anchor": "Constrained-search density functional study of quantum transport in\n  two-dimensional vertical heterostructures: Based on a microcanonical picture that maps the steady-state quantum\ntransport process to a drain-to-source excitation, we develop a\nconstrained-search density functional formalism for finite-bias quantum\ntransport calculations. By variationally minimizing the total energy of an\nelectrode-channel-electrode system without introducing separate bulk electrode\ninformation, ambiguities in identifying its nonequilibrium electronic structure\nunder a bias is reduced and finite electrode cases can be naturally treated. We\napply the approach to vertically stacked van der Waals heterostructures made of\na hexagonal boron nitride (hBN) channel sandwiched by single-layer graphene\nelectrodes, which so far could not be treated within first-principles\ncalculations. We find that the experimentally observed negative differential\nresistance originates from the hBN defect-mediated hybridizations between two\ngraphene states, and concurrently obtain a high-bias linear current increase\nthat was not captured in previous semiclassical treatments. Going beyond the\ncapability of existing $ab\\ initio$ nonequilibrium quantum transport simulation\nmethods, the developed formalism will provide valuable atomistic information in\nthe development of next-generation nanodevices.",
        "positive": "Do intradot electron-electron interactions induce dephasing?: We investigate the degree of coherence of electronic transport through a\nquantum dot (QD) in the presence of an intradot electron-electron interaction.\nBy using an open multi-terminal Aharonov-Bohm (AB) setup, we find that the\nintradot interaction does not induce any dephasing effect and the electron\ntransport through the QD is fully coherent. We also observe that the asymmetric\namplitude of the AB oscillation in the conductance through the two-terminal AB\nsetup originates from the interplay between the confined structure and the\nelectron-electron interaction. Thus, one can not associate a dephasing process\nwith this asymmetric amplitude, as has been done in previous studies."
    },
    {
        "anchor": "Nonlinear microwave photon-occupancy of a driven resonator strongly\n  coupled to a transmon qubit: We measure photon-occupancy in a thin-film superconducting lumped element\nresonator coupled to a transmon qubit at 20$\\,$mK and find a nonlinear\ndependence on the applied microwave power. The transmon-resonator system was\noperated in the strong dispersive regime, where the ac Stark shift ($2\\chi$)\ndue to a single microwave photon present in the resonator was larger than the\nlinewidth ($\\Gamma$) of the qubit transition. When the resonator was coherently\ndriven at $5.474325\\,$GHz, the transition spectrum of the transmon at\n$4.982\\,$GHz revealed well-resolved peaks, each corresponding to an individual\nphoton number-state of the resonator. From the relative peak-heights we obtain\nthe occupancy of the photon-states and the average photon-occupancy $\\bar{n}$\nof the resonator. We observed a nonlinear variation of $\\bar{n}$ with the\napplied drive power $P_{rf}$ for $\\bar{n} < 5$ and compare our results to\nnumerical simulations of the system-bath master equation in the steady state,\nas well as to a semi-classical model for the resonator that includes the\nJaynes-Cummings interaction between the transmon and the resonator. We find\ngood quantitative agreement using both models and analysis reveals that the\nnonlinear behavior is principally due to shifts in the resonant frequency\ncaused by a qubit-induced Jaynes-Cummings nonlinearity.",
        "positive": "Near field enhancement due to the optical response of small\n  nanoparticles: In this work we study the strong confinement effects on the electromagnetic\nresponse of metallic nanoparticles. We calculate the field enhancement factor\nfor nanospheres of various radii by using optical constants obtained from both\nclassical and quantum approaches and compare their size-dependent features. To\nevaluate the scattered near-field, we solve the electromagnetic wave equation\nwithin a finite element framework. When quantization of electronic states is\nconsidered for the input optical functions, a significant blue-shift in the\nresonance of the enhanced field is observed, in contrast to the case in which\nfunctions obtained classically are used. Furthermore, a noticeable\nunderestimation of the field amplification is found in the calculation based on\na classical dielectric function. Our results are in good agreement with\navailable experimental reports and provide relevant information on the\ncross-over between classical and quantum regime, useful in potentiating\nnanoplasmonics applications."
    },
    {
        "anchor": "Coexistence and interconvertibility of ferromagnetic and\n  antiferromagnetic phases in the single crystal of Mn$_3$ single-molecule\n  magnet: We report the coexistence of ferromagnetic and antiferromagnetic phases in\nthe single crystal of Mn$_3$ single-molecule magnet. The coexistent state\nappears within a certain period of time in the progress of either oxidation or\nreduction during a reversible oxidation-reduction process, when the sample is\nexposed in the air (oxygen) or the methyl vapor. We noticed an apparent change\nin the molecular structure, which is also reversible in terms of that the\nmethyl group is dropped or added to the molecules during the oxidation or\nreduction. The absence or presence of the methyl group in the molecules exert\nan essential impact upon the intermolecular exchange interaction, and the\nferromagnetic phase comes from the heterogenous intermolecular bonds between\npairs of molecules of which one molecule has a methyl group whereas the other\nhas lost the methyl group. The reversible change in molecular structure\nsuggests the magnetic structure of Mn$_3$ might be designed and modulated at\nmolecular scale, which implies Mn$_3$ has a great application potential.",
        "positive": "Isolated nearly flat higher Chern band in monolayer transition metal\n  trihalides: The interplay between non-trivial topology and strong electron interaction\ncan generate a variety of exotic quantum matter. Here we theoretically propose\nthat monolayer transition metal trihalides MoF$_3$ and WI$_3$ have isolated\nnearly flat band near the Fermi level with higher Chern number $\\mathcal{C}=+3$\nand $\\mathcal{C}=-2$, respectively. The nontrivial topology of these flat Chern\nbands originates from the effective $sd^2$ hybridization of transition metal\natom, which transform the apparent atomic $d$ orbitals on a hexagonal lattice\ninto $(s, p_+, p_-)$ orbitals on a triangular lattice. Interestingly, the\nquantum geometry of flat Chern bands in both materials are comparable with\nthose in moir\\'e systems exhibiting fractional Chern insulator state. The\nHofstadter butterfly of such flat Chern bands are further studied. These\nnatural materials, if realized experimentally, could offer new platforms to\nexplore correlated phenomena driven by flat Chern band with higher Chern\nnumber."
    },
    {
        "anchor": "Ab initio study of the nonlinear optical properties and d.c.\n  photocurrent of the Weyl semimetal TaIrTe$_4$: We present a first principles theoretical study employing nonlinear response\ntheory to investigate the d.c. photocurrent generated by linearly polarized\nlight in the type-II Weyl semimetal TaIrTe4. We report the low energy spectrum\nof several nonlinear optical effects. At second-order, we consider the shift\nand injection currents. Assuming the presence of a built-in static electric\nfield, at third-order we study the current-induced shift and injection\ncurrents, as well as the jerk current. We discuss our results in the context of\na recent experiment measuring an exceptionally large photoconductivity in this\nmaterial [J. Ma et at., Nat. Mater. 18, 476 (2019)]. According to our results,\nthe jerk current is the most likely origin of the large response. Finally, we\npropose means to discern the importance of the various mechanisms involved in a\ntime-resolved experiment.",
        "positive": "Intrinsic interface adsorption drives selectivity in atomically smooth\n  nanofluidic channels: Specific molecular interactions underlie unexpected and useful phenomena in\nnanofluidic systems, but require descriptions that go beyond traditional\nmacroscopic hydrodynamics. In this letter, we demonstrate how equilibrium\nmolecular dynamics simulations and linear response theory can be synthesized\nwith hydrodynamics to provide a comprehensive characterization of nanofluidic\ntransport. Specifically, we study the pressure driven flows of ionic solutions\nin nanochannels comprised of two-dimensional crystalline substrates made from\ngraphite and hexagonal boron nitride. While simple hydrodynamic descriptions do\nnot predict a streaming electrical current or salt selectivity in such simple\nsystems, we observe that both arise due to the intrinsic molecular interactions\nthat act to selectively adsorb ions to the interface in the absence of a net\nsurface charge. Notably, this emergent selectivity indicates that these\nnanochannels can serve as desalination membranes."
    },
    {
        "anchor": "Novel Majorana mode and magnetoresistance in ferromagnetic\n  superconducting topological insulator: Among the potential applications of topological insulators, we investigate\ntheoretically the effect of coexistence of proximity-induced ferromagnetism and\nsuperconductivity on the surface states of 3-dimensional topological insulator,\nwhere the superconducting electron-hole excitations can be significantly\naffected by the magnetization of ferromagnetic order. We find that, Majorana\nmode energy, as a verified feature of TI F/S structure, along the interface\nsensitively depends on the magnitude of magnetization $m_{zfs}$ in FS region,\nwhile its slope in perpendicular incidence presents steep and no change. Since\nthe superconducting gap is renormalized by a factor $\\eta(m_{zfs})$, hence\nAndreev reflection is more or less suppressed, and, in particular, resulting\nsubgap tunneling conductance is more sensitive to the magnitude of\nmagnetizations in FS and F regions. Furthermore, an interesting scenario\nhappens at the antiparallel configuration of magnetizations $m_{zf}$ and\n$m_{zfs}$ resulting in magnetoresistance in N/F/FS junction, which can be\ncontrolled and decreased by tuning the magnetization magnitude in FS region.",
        "positive": "Mesoscopic Kondo Effect in an Aharonov-Bohm Ring: An interacting quantum dot inserted in a mesoscopic ring is investigated. A\nvariational ansatz is employed to describe the ground state of the system in\nthe presence of the Aharonov-Bohm flux. It is shown that, for even number of\nelectrons with the energy level spacing smaller than the Kondo temperature, the\npersistent current has a value similar to that of a perfect ring with the same\nradius. On the other hand, for a ring with odd number electrons, the persistent\ncurrent is found to be strongly suppressed compared to that of an ideal ring,\nwhich implies the suppression of the Kondo-resonant transmission. Various\naspects of the Kondo-assisted persistent current are discussed."
    },
    {
        "anchor": "Charge Density Wave Ratchet: We propose to operate a locally-gated charge density wave as an electron\npump. Applying an oscillating gate potential with frequency $f$ causes equally\nspaced plateaux in the sliding charge density wave current separated by $\\Delta\nI=2eNf,$ where $N$ is the number of parallel chains. The effects of thermal\nnoise are investigated.",
        "positive": "Dimensional Reduction of Helium-4 Inside Argon Plated MCM-41 Nanopores: The angstrom-scale coherence length describing the superfluid wavefunction of\nhelium-4 at low temperatures has prevented its preparation in a truly\none-dimensional geometry. Mesoporous ordered silica-based structures, such as\nthe molecular sieve MCM-41, offer a promising avenue towards physical\nconfinement, but the minimal pore diameters that can be chemically synthesized\nhave proven to be too large to reach the quasi-one-dimensional limit. We\npresent an active nano-engineering approach to this problem by pre-plating\nMCM-41 with a single, well controlled layer of Ar gas before filling the pores\nwith helium. The structure inside the pore is investigated via experimental\nadsorption isotherms and neutron scattering measurements that are in agreement\nwith large scale quantum Monte Carlo simulations. The results demonstrate\nangstrom and kelvin scale tunability of the effective confinement potential\nexperienced by 4He atoms inside the MCM-41, with the Ar layer reducing the\ndiameter of the confining media into a regime where a number of solid layers\nsurround a one-dimensional quantum liquid."
    },
    {
        "anchor": "Optical Properties of Monolayer Tinene in Electric Fields: Monolayer tinene presents rich absorption spectra in electric fields. There\nare three kinds of special structures, namely shoulders, logarithmically\nsymmetric peaks and asymmetric peaks in the square-root form, corresponding to\nthe optical excitations of the extreme points, saddle points and\nconstant-energy loops. With the increasing field strength, two splitting\nshoulder structures, which are dominated by the parabolic bands of ${5p_z}$\norbitals, come to exist because of the spin-split energy bands. The frequency\nof threshold shoulder declines to zero and then linearly grows. The third\nshoulder at ${0.75 \\sim 0.85}$ eV mainly comes from (${5p_x,5p_y}$) orbitals.\nThe former and the latter orbitals, respectively, create the saddle-point\nsymmetric peaks near the M point, while they hybridize with one another to\ngenerate the loop-related asymmetric peaks. Tinene quite differs from graphene,\nsilicene, and germanene. The special relationship among the multi-orbital\nchemical bondings, spin-orbital couplings and Coulomb potentials accounts for\nthe feature-rich optical properties.",
        "positive": "Shot noise of a mesoscopic two-particle collider: We investigate the shot noise generated by particle emission from a\nmesoscopic capacitor into an edge state reflected and transmitted at a quantum\npoint contact (QPC). For a capacitor subject to a periodic voltage the\nresulting shot noise is proportional to the number of particles (both electrons\nand holes) emitted during a period. It is proportional to the product of\ntransmission and reflection probability of the QPC independent of the applied\nvoltage but proportional to the driving frequency. If two driven capacitors are\ncoupled to a QPC at different sides then the resulting shot noise is maximally\nthe sum of noises produced by each of the capacitors. However the noise is\nsuppressed depending on the coincidence of the emission of two particles of the\nsame kind."
    },
    {
        "anchor": "Effect of Spin-Orbit Interaction and In-Plane Magnetic Field on the\n  Conductance of a Quasi-One-Dimensional System: We study the effect of spin-orbit interaction and in-plane effective magnetic\nfield on the conductance of a quasi-one-dimensional ballistic electron system.\nThe effective magnetic field includes the externally applied field, as well as\nthe field due to polarized nuclear spins. The interplay of the spin-orbit\ninteraction with effective magnetic field significantly modifies the band\nstructure, producing additional sub-band extrema and energy gaps, introducing\nthe dependence of the sub-band energies on the field direction. We generalize\nthe Landauer formula at finite temperatures to incorporate these special\nfeatures of the dispersion relation. The obtained formula describes the\nconductance of a ballistic conductor with an arbitrary dispersion relation.",
        "positive": "Real-space entanglement spectrum of quantum Hall systems: We study the real-space entanglement spectrum for fractional quantum Hall\nsystems, which maintains locality along the spatial cut, and provide evidence\nthat it possesses a scaling property. We also consider the closely-related\nparticle entanglement spectrum, and carry out the Schmidt decomposition of the\nLaughlin state analytically at large size."
    },
    {
        "anchor": "Josephson junctions and superconducting quantum interference devices\n  made by local oxidation of niobium ultrathin films: We present a method for fabricating Josephson junctions and superconducting\nquantum interference devices (SQUIDs) which is based on the local anodization\nof niobium strip lines 3 to 6.5 nm-thick under the voltage-biased tip of an\nAtomic Force Microscope. Microbridge junctions and SQUID loops are obtained\neither by partial or total oxidation of the niobium layer. Two types of weak\nlink geometries are fabricated : lateral constriction (Dayem bridges) and\nvariable thickness bridges. SQUIDs based on both geometries show a modulation\nof the maximum Josephson current with a magnetic flux periodic with respect to\nthe superconducting flux quantum h/2e. They persist up to 4K. The modulation\nshape and depth for SQUIDs based on variable thickness bridges indicate that\nthe weak link size becomes comparable to the superconducting film coherence\nlength which is of the order of 10nm.",
        "positive": "Twist-angle dependent proximity induced spin-orbit coupling in\n  graphene/transition-metal dichalcogenide heterostructures: We investigate the proximity-induced spin-orbit coupling in heterostructures\nof twisted graphene and monolayers of transition-metal dichalcogenides (TMDCs)\nMoS$_2$, WS$_2$, MoSe$_2$, and WSe$_2$ from first principles. We identify\nstrain, which is necessary to define commensurate supercells, as the key factor\naffecting the band offsets and thus magnitudes of the proximity couplings. We\nestablish that for biaxially strained graphene the band offsets between the\nDirac point and conduction (valence) TMDC bands vary linearly with strain,\nregardless of the twist angle. This relation allows to identify the apparent\nzero-strain band offsets and find a compensating transverse electric field\ncorrecting for the strain. The resulting corrected band structure is then\nfitted around the Dirac point to an established spin-orbit Hamiltonian. This\nprocedure yields the dominant, valley-Zeeman and Rashba spin-orbit couplings.\nThe magnitudes of these couplings do not vary much with the twist angle,\nalthough the valley-Zeeman coupling vanishes for 30$^{\\circ}$ and Mo-based\nheterostructures exhibit a maximum of the coupling at around 20$^{\\circ}$. The\nmaximum for W-based stacks is at 0$^{\\circ}$. The Rashba coupling is in general\nweaker than the valley-Zeeman coupling, except at angles close to 30$^{\\circ}$.\nWe also identify the Rashba phase angle which measures the deviation of the\nin-plane spin texture from tangential, and find that this angle is very\nsensitive to the applied transverse electric field. We further discuss the\nreliability of the supercell approach with respect to atomic relaxation\n(rippling of graphene), relative lateral shifts of the atomic layers, and\ntransverse electric field."
    },
    {
        "anchor": "Simultaneous observation of small- and large-energy-transfer\n  electron-electron scattering in three dimensional indium oxide thick films: In three dimensional (3D) disordered metals, the electron-phonon\n(\\emph{e}-ph) scattering is the sole significant inelastic process. Thus the\ntheoretical predication concerning the electron-electron (\\emph{e}-\\emph{e})\nscattering rate $1/\\tau_\\varphi$ as a function of temperature $T$ in 3D\ndisordered metal has not been fully tested thus far, though it was proposed 40\nyears ago [A. Schmid, Z. Phys. \\textbf{271}, 251 (1974)]. We report here the\nsimultaneous observation of small- and large-energy-transfer \\emph{e}-\\emph{e}\nscattering in 3D indium oxide thick films. In temperature region of\n$T\\gtrsim100$\\,K, the temperature dependence of resistivities curves of the\nfilms obey Bloch-Gr\\\"{u}neisen law, indicating the films possess degenerate\nsemiconductor characteristics in electrical transport property. In the low\ntemperature regime, $1/\\tau_\\varphi$ as a function of $T$ for each film can not\nbe ascribed to \\emph{e}-ph scattering. To quantitatively describe the\ntemperature behavior of $1/\\tau_\\varphi$, both the 3D small- and\nlarge-energy-transfer \\emph{e}-\\emph{e} scattering processes should be\nconsidered (The small- and large-energy-transfer \\emph{e}-\\emph{e} scattering\nrates are proportional to $T^{3/2}$ and $T^2$, respectively). In addition, the\nexperimental prefactors of $T^{3/2}$ and $T^{2}$ are proportional to\n$k_F^{-5/2}\\ell^{-3/2}$ and $E_F^{-1}$ ($k_F$ is the Fermi wave number, $\\ell$\nis the electron elastic mean free path, and $E_F$ is the Fermi energy),\nrespectively, which are completely consistent with the theoretical\npredications. Our experimental results fully demonstrate the validity of\ntheoretical predications concerning both small- and large-energy-transfer\n\\emph{e}-\\emph{e} scattering rates.",
        "positive": "Control of the nonlinear frequency shift for the spin-transfer\n  nanooscillator using a bias magnetic field: We investigated the possibilities of controlling the nonlinear frequency\nshift of the magnetization oscillations in a spin-transfer nanoscillator by\nvarying the magnitude and direction of the bias magnetic field. We considered\nboth isotropic ferromagnetic materials and crystals with uniaxial and cubic\ncrystallographic anisotropies. We have shown that achieving a zero nonlinear\nfrequency shift is possible with a certain orientation of the bias magnetic\nfield vector. The results of the theoretical analysis based on the method of\nHamiltonian formalism are in good agreement with the micromagnetic simulations.\nOur research reveals the way to control the frequency tuning of a spin transfer\nnanoscillator, which is crucial for spintronic signal generation devices."
    },
    {
        "anchor": "Plasmon Excitations for Encapsulated Graphene: We have developed an analytical formulation to calculate the plasmon\ndispersion relation for a two-dimensional layer which is encapsulated within a\nnarrow spatial gap between two bulk half-space plasmas. This is based on a\nsolution of the inverse dielectric function integral equation within the\nrandom-phase approximation (RPA). We take into account the nonlocality of the\nplasmon dispersion relation for both gapped and gapless graphene as the\nsandwiched two-dimensional (2D) semiconductor plasma. The associated nonlocal\ngraphene plasmon spectrum coupled to the \"sandwich\" system is exhibited in\ndensity plots, which show a linear mode and a pair of depolarization modes\nshifted from the bulk plasma frequency.",
        "positive": "Fusion of Majorana Bound States with Mini-Gate Control in\n  Two-Dimensional Systems: A hallmark of topological superconductivity is the non-Abelian statistics of\nMajorana bound states (MBS), its chargeless zero-energy emergent\nquasiparticles. The resulting fractionalization of a single electron, stored\nnonlocally as a two spatially-separated MBS, provides a powerful platform for\nimplementing fault-tolerant topological quantum computing. However, despite\nintensive efforts, experimental support for MBS remains indirect and does not\nprobe their non-Abelian statistics. Here we propose how to overcome this\nobstacle in mini-gate controlled planar Josephson junctions (JJs) and\ndemonstrate non-Abelian statistics through MBS fusion, detected by charge\nsensing using a quantum point contact, based on dynamical simulations. The\nfeasibility of preparing, manipulating, and fusing MBS in two-dimensional (2D)\nsystems is supported in our experiments which demonstrate the gate control of\ntopological transition and superconducting properties with five mini gates in\nInAs/Al-based JJs. While we focus on this well-established platform, where the\ntopological superconductivity was already experimentally detected, our proposal\nto identify elusive non-Abelian statistics motivates also further MBS studies\nin other gate-controlled 2D systems."
    },
    {
        "anchor": "Conductance quantization in graphene nanoribbons: Adiabatic\n  approximation: A theory of electron states for graphene nanoribbons with a smoothly varying\nwidth is developed. It is demonstrated that the standard adiabatic\napproximation allowing to neglect the mixing of different standing waves is\nmore restrictive for the massless Dirac fermions in graphene than for the\nconventional electron gas. For the case of zigzag boundary conditions, one can\nexpect a well-pronounced conductance quantization only for highly excited\nstates. This difference is related to the relativistic Zitterbewegung effect in\ngraphene.",
        "positive": "Spin wave nonreciprocity and magnonic band structure in thin permalloy\n  film induced by dynamical coupling with an array of Ni stripes: An efficient way for the control of spin wave propagation in a magnetic\nmedium is the use of periodic patterns known as magnonic crystals (MCs).\nHowever, the fabrication of MCs especially bi-components, with periodicity on\nnanoscale, is a challenging task due to the requirement for sharp interfaces.\nAn alternative method to circumvent this problem is to use homogeneous\nferromagnetic film with modified periodically surrounding. The structure is\nalso suitable for exploiting nonreciprocal properties of the surface spin\nwaves. In this work, we demonstrate that the magnonic band structure forms in\nthin permalloy film due to dynamical magnetostatic coupling with Ni stripes\nnear its surface. We show, that the band gap width can be systematically tuned\nby the changing interlayer thickness between film and stripes. We show also the\neffect of nonreciprocity, which is seen at the band gap edge shifted from the\nBrillouin zone boundary and also in nonreciprocal interaction of propagating\nspin waves in Py film with the standing spin waves in Ni stripes. Our findings\nopen possibility for further investigation and exploitation of the\nnonreciprocity and band structure in magnonic devices."
    },
    {
        "anchor": "Intersubband Edge Singularity in Metallic Nanotubes: Tunneling density of states of both the massless and massive (gapped)\nparticles in metallic carbon nanotubes is known to have anomalous energy\ndependence. This is the result of coupling to multiple low-energy bosonic\nexcitation (plasmons). For both kinds of particles the ensuing effect is the\nsuppression of the density of states by electron-electron interactions. We\ndemonstrate that the optical absorption between gapless and gapped states is\naffected by the many-body effects in the opposite way. The absorption\nprobability is enhanced compared with the non-interacting value and develops a\npower-law frequency dependence with the exponent -0.2 for typical nanotubes.",
        "positive": "Veelvoudige verstrooiing van golven: These are notes (in Dutch) of lectures on multiple scattering of waves, given\nat the University of Amsterdam in 1993. At request of some of the students, now\nprofessors, they are made publicly available.\n  The main part of the material is covered in the review paper: {\\it Multiple\nscattering of classical waves: microscopy, mesoscopy, and diffusion,} by M. C.\nW. van Rossum and myself, Rev. Mod. Phys. {\\bf 71} (1999) 313 - 371."
    },
    {
        "anchor": "Spin-Currents and Spin-Pumping Forces for Spintronics: A general definition of the Spintronics concept of spin-pumping is proposed\nas generalized forces conjugated to the spin degrees of freedom in the\nframework of the theory of mesoscopic non-equilibrium thermodynamics. It is\nshown that at least three different kinds of spin-pumping forces and associated\nspin-currents can be defined in the most simple spintronics system (the\nFerromagnetic/Non-Ferromagnetic metal interface). Furthermore, the generalized\nforce associated to the ferromagnetic collective variable is also introduced in\nan equal footing, in order to describe the coexistence of the spin of the\nconduction electrons (paramagnetic spins attached to $s$-band electrons) and\nthe ferromagnetic-order parameter. The dynamical coupling between these two\nkinds of magnetic degrees of freedom is presented, and interpreted in terms of\nspin-transfer effects.",
        "positive": "Extraordinary absorption of decorated undoped graphene: We theoretically study absorption by an undoped graphene layer decorated with\narrays of small particles. We discuss periodic and random arrays within a\ncommon formalism, which predicts a maximum absorption of $50\\%$ for suspended\ngraphene in both cases. The limits of weak and strong scatterers are\ninvestigated and an unusual dependence on particle-graphene separation is found\nand explained in terms of the effective number of contributing evanescent\ndiffraction orders of the array. Our results can be important to boost\nabsorption by single layer graphene due to its simple setup with potential\napplications to light harvesting and photodetection based on energy (F\\\"orster)\nrather than charge transfer."
    },
    {
        "anchor": "Electrical control of a spin qubit in InSb nanowire quantum dots:\n  strongly suppressed spin relaxation in high magnetic field: In this paper, we investigate the impact of gating potential and magnetic\nfield on phonon induced spin relaxation rate and the speed of the electrically\ndriven single-qubit operations inside the InSb nanowire spin qubit. We show\nthat a strong $g$ factor and high magnetic field strength lead to the\nprevailing influence of electron-phonon scattering due to deformation\npotential, considered irrelevant for materials with a weak $g$ factor, like\nGaAs or Si/SiGe. In this regime, we find that spin relaxation between qubit\nstates is significantly suppressed due to the confinement perpendicular to the\nnanowire axis. We also find that maximization of the number of single-qubit\noperations that can be performed during the lifetime of the spin qubit requires\nsingle quantum dot gating potential.",
        "positive": "Classical and quantum spreading of a charge pulse: With the technical progress of radio-frequency setups, high frequency quantum\ntransport experiments have moved from theory to the lab. So far the standard\ntheoretical approach used to treat such problems numerically--known as Keldysh\nor NEGF (Non Equilibrium Green's Functions) formalism--has not been very\nsuccessful mainly because of a prohibitive computational cost. We propose a\nreformulation of the non-equilibrium Green's function technique in terms of the\nelectronic wave functions of the system in an energy-time representation. The\nnumerical algorithm we obtain scales now linearly with the simulated time and\nthe volume of the system, and makes simulation of systems with 10^5 - 10^6\natoms/sites feasible. We illustrate our method with the propagation and\nspreading of a charge pulse in the quantum Hall regime. We identify a classical\nand a quantum regime for the spreading, depending on the number of particles\ncontained in the pulse. This numerical experiment is the condensed matter\nanalogue to the spreading of a Gaussian wavepacket discussed in quantum\nmechanics textbooks."
    },
    {
        "anchor": "Topological Peierls Transitions in M\u00f6bius Molecular Devices: We study the topological properties of Peierls transitions in a monovalent\nM\\\"{o}bius ladder. Along the transverse and longitudinal directions of the\nladder, there exist plenty Peierls phases corresponding to various dimerization\npatterns. Resulted from a special modulation, namely, staggered modulation\nalong the longitudinal direction, the ladder system in the insulator phase\nbehaves as a ``topological insulator'', which possesses charged solitons as the\ngapless edge states existing in the gap. Such solitary states promise the\ndispersionless propagation along the longitudinal direction of the ladder\nsystem. Intrinsically, these non-trivial edges states originates from the\nPeierls phases boundary, which arises from the non-trivial $\\mathbb{Z}^{2}$\ntopological configuration.",
        "positive": "Resonant excitation of acoustic waves in one-dimensional\n  exciton-polariton systems: We analyze the interaction of exciton-polariton condensates in a\none-dimensional semiconductor microcavity with acoustic phonons. We consider\nthe case of a coherently pumped condensate and demonstrate that upon passing of\na certain threshold the parametric instability in the system leads to the\ngeneration of a coherent acoustic wave and additional polariton harmonics. The\nprocess is strongly affected by exciton-exciton interactions which lead to the\nappearance of the effects of the bistability and hysteresis in the system."
    },
    {
        "anchor": "Three-electron spin qubits: The goal of this article is to review the progress of three-electron spin\nqubits from their inception to the state of the art. We direct the main focus\ntowards the resonant exchange (RX) qubit and the exchange-only qubit, but we\nalso discuss other qubit implementations using three electron spins. For each\nthree-spin qubit we describe the qubit model, the physical realization, the\nimplementations of single-qubit operations, as well as the read-out and\ninitialization schemes. Two-qubit gates and decoherence properties are\ndiscussed for the RX qubit and the exchange-only qubit, thereby, completing the\nlist of requirements for a viable candidate qubit implementation for quantum\ncomputation. We start with describing the full system of three electrons in a\ntriple quantum dot, then discuss the charge-stability diagram and restrict\nourselves to the relevant subsystem, introduce the qubit states, and discuss\nimportant transitions to other charge states. Introducing the various qubit\nimplementations, we begin with the exchange-only qubit, followed by the\nspin-charge qubit, the hybrid qubit, and the RX qubit, discussing for each the\nsingle-qubit operations, read-out, and initialization methods, whereas the main\nfocus will be on the RX qubit, whose single-qubit operations are realized by\ndriving the qubit at its resonant frequency in the microwave range similar to\nelectron spin resonance. Two different types of two-qubit operations are\npresented for the exchange-only and the RX qubit which can be divided into\nshort-ranged and long-ranged interactions. Both of these interaction types can\nbe expected to be necessary in a large-scale quantum computer. We also take\ninto account the decoherence of the qubit through the influence of magnetic\nnoise as well as dephasing due to charge noise.",
        "positive": "Passivation-sensitive exciton finestructure produces excess Stokes\n  shifts in colloidal quantum dots: The excitonic finestructure of colloidal quantum dots (CQDs) is comprised of\na manifold of transitions, of which only the lowest are populated and\ncontribute to photoluminescence. This leads to a Stokes shift in emission\nrelative to absorption. Here we show experimentally that the Stokes shift in Pb\nand Cd-based chalcogenide CQDs is correlated with the degree of surface\npassivation, and develop a model that explains how coupling to the surface\naffects the core electronic states. Dark and bright transitions can reorder and\nsplit, increasing the Stokes shift even without the formation of deep traps.\nOur findings resolve the highly-debated topic of excess Stokes shifts in PbS\nnanocrystals as due to parity-forbidden transitions instead of traps. We\npredict that the Stokes shift in PbS can be eliminated via core stoichiometry\ncontrol, a critical step towards enhancing the open circuit voltage in quantum\ndot solar cells."
    },
    {
        "anchor": "New mechanism for generating spin transfer torque without charge current: A new physical mechanism for generating spin-transfer torque is proposed. It\nis due to interference of bias driven nonequilibrium electrons incident on a\nswitching junction with the electrons reflected from an insulating barrier\ninserted in the junction after the switching magnet. It is shown using the\nrigorous Keldysh formalism that this new out-of-plane torque $T_{\\perp}$ is\nproportional to an applied bias and is as large as the torque in a conventional\njunction generated by a strong charge current. However, the charge current and\nthe in-plane torque $T_{\\parallel}$ are almost completely suppressed by the\ninsulating barrier. This new junction thus offers the highly applicable\npossibility of bias-induced switching of magnetization without charge current.",
        "positive": "Engineering of topological phases in driven thin topological insulator:\n  Structure inversion asymmetry effect: We investigate the effect of a high frequency electromagnetic field with both\nof circularly and linearly polarization, on the emergence of quantum phases on\nthin topological insulators. Simultaneously, the influence of the system\nparameters (such as magnetic impurity, thickness engineering and structural\ninversion asymmetry of the potential) on emergence of topological phases is\nstudied. We take our attention to the high frequency regime in which it is\npossible to consider an expansion for the Floquet Hamiltonian in terms of\norders of 1/\\Omega. The topological invariants are determined and it is\ndemonstrated that some phase transitions between quantum anomalous Hall\ninsulator, quantum pseudospin Hall insulator, quantum spin Hall insulator and\nnormal insulator can be induced by altering the aforementioned parameters of\nthe system. To avoid heating process, tuning of the system parameters gives us\nthe opportunity to observe these phase transitions at small intensities of\nlight."
    },
    {
        "anchor": "Analysis of the exciton-exciton interaction in semiconductor quantum\n  wells: The exciton-exciton interaction is investigated for quasi-two-dimensional\nquantum structures. A bosonization scheme is applied including the full spin\nstructure. For generating the effective interaction potentials, the\nHartree-Fock and Heitler-London approaches are improved by a full two-exciton\ncalculation which includes the van der Waals effect. With these potentials the\nbiexciton formation in bilayer systems is investigated. For coupled quantum\nwells the two-body scattering matrix is calculated and employed to give a\nmodified relation between exciton density and blue shift. Such a relation is of\ncentral importance for gauging exciton densities in experiments which pave the\nway toward Bose-Einstein condensation of excitons.",
        "positive": "Magnetic field control of the Franck-Condon coupling of few-electron\n  quantum states: Suspended carbon nanotubes display at cryogenic temperatures a distinct\ninteraction between the quantized longitudinal vibration of the macromolecule\nand its embedded quantum dot, visible via Franck-Condon conductance side bands\nin transport spectroscopy. We present data on such side bands at known absolute\nnumber N=1 and N=2 of conduction band electrons and consequently well-defined\nelectronic ground and excited states in a clean nanotube device. The\ninteraction evolves only at a finite axial magnetic field and displays a\ndistinct magnetic field dependence of the Franck-Condon coupling, different for\ndifferent electronic base states and indicating a valley-dependent\nelectron-vibron coupling. A tentative cause of these effects, reshaping of the\nelectronic wavefunction by the magnetic field, is discussed and demonstrated in\na model."
    },
    {
        "anchor": "Two-photon interference from remote deterministic quantum dot\n  microlenses: We report on two-photon interference (TPI) experiments using remote\ndeterministic single-photon sources. Employing 3D in-situ electron-beam\nlithography, we fabricate quantum-light sources at specific target wavelengths\nby integrating pre-selected semiconductor quantum dots within monolithic\nmicrolenses. The individual single-photon sources show TPI visibilities of 49%\nand 22%, respectively, under pulsed p-shell excitation at 80 MHz. For the\nmutual TPI of the remote sources, we observe an uncorrected visibility of 29%,\nin quantitative agreement with the pure dephasing of the individual sources.\nDue to its efficient photon extraction within a broad spectral range (> 20 nm),\nour microlens-based approach is predestinated for future entanglement swapping\nexperiments utilizing entangled photon pairs emitted by distant\nbiexciton-exciton radiative cascades.",
        "positive": "Grain Boundaries in Graphene on SiC(000$\\bar{1}$) Substrate: Grain boundaries in epitaxial graphene on the SiC(000$\\bar{1}$) substrate are\nstudied using scanning tunneling microscopy and spectroscopy. All investigated\nsmall-angle grain boundaries show pronounced out-of-plane buckling induced by\nthe strain fields of constituent dislocations. The ensemble of observations\nallows to determine the critical misorientation angle of buckling transition\n$\\theta_c = 19 \\pm~2^\\circ$. Periodic structures are found among the flat\nlarge-angle grain boundaries. In particular, the observed $\\theta =\n33\\pm2^\\circ$ highly ordered grain boundary is assigned to the previously\nproposed lowest formation energy structural motif composed of a continuous\nchain of edge-sharing alternating pentagons and heptagons. This periodic grain\nboundary defect is predicted to exhibit strong valley filtering of charge\ncarriers thus promising the practical realization of all-electric valleytronic\ndevices."
    },
    {
        "anchor": "Can mesoscopic fluctuations reverse the supercurrent through a\n  disordered Josephson junction?: We calculate the Josephson coupling energy $U_J(\\phi)$ (related to the\nsupercurrent $I=(2e/\\hbar) dU_J/d\\phi$) for a disordered normal metal between\ntwo superconductors with a phase difference $\\phi$. We demonstrate that the\nsymmetry of the scattering matrix of non-interacting quasiparticles in zero\nmagnetic field implies that $U_J(\\phi)$ has a minimum at $\\phi=0$. A maximum\n(that would lead to a $\\pi$-junction or negative superfluid density) is\nexcluded for any realization of the disorder.",
        "positive": "Cluster Algorithms for Quantum Impurity Models and Mesoscopic Kondo\n  Physics: Nanoscale physics and dynamical mean field theory have both generated\nincreased interest in complex quantum impurity problems and so have focused\nattention on the need for flexible quantum impurity solvers. Here we\ndemonstrate that the mapping of single quantum impurity problems onto\nspin-chains can be exploited to yield a powerful and extremely flexible\nimpurity solver. We implement this cluster algorithm explicitly for the\nAnderson and Kondo Hamiltonians, and illustrate its use in the ``mesoscopic\nKondo problem''. To study universal Kondo physics, a large ratio between the\neffective bandwidth $D_\\mathrm{eff}$ and the temperature $T$ is required; our\ncluster algorithm treats the mesoscopic fluctuations exactly while being able\nto approach the large $D_\\mathrm{eff}/T$ limit with ease. We emphasize that the\nflexibility of our method allows it to tackle a wide variety of quantum\nimpurity problems; thus, it may also be relevant to the dynamical mean field\ntheory of lattice problems."
    },
    {
        "anchor": "Model for Dissipative Conductance in Fractional Quantum Hall States: We present a model of dissipative transport in the fractional quantum Hall\nregime. Our model takes account of tunneling through saddle points in the\neffective potential for excitations created by impurities. We predict the\ntemperature range over which activated behavior is observed and explain why\nthis range nearly always corresponds to around a factor two in temperature in\nboth integer quantum Hall and fractional quantum Hall systems. We identify the\nratio of the gap observed in the activated behavior and the temperature of the\ninflection point in the Arrhenius plot as an important diagnostic for\ndetermining the importance of tunneling in real samples.",
        "positive": "Interplay of electromagnetic noise and Kondo effect in quantum dots: We investigate the influence of an electromagnetic environment, characterized\nby a finite impedance $Z(\\omega)$, on the Kondo effect in quantum dots. The\ncircuit voltage fluctuations couple to charge fluctuations in the dot and\ninfluence the spin exchange processes transferring charge between the\nelectrodes. We discuss how the low-energy properties of a Kondo quantum dot\nsubject to dynamical Coulomb blockade resemble those of Kondo impurities in\nLuttinger liquids. Using previous knowledge based on the bosonization of\nquantum impurity models, we show that low-voltage conductance anomalies appear\nat zero temperature. The conductance can vanish at low temperatures even in\npresence of a screened impurity spin. Moreover, the quantitative determination\nof the corresponding Kondo temperature depends on the full frequency-dependent\nimpedance of the circuit. This is demonstrated by a weak-coupling calculation\nin the Kondo interaction, taking into account the full distribution $P(E)$ of\nexcited environmental modes."
    },
    {
        "anchor": "Coherent population transfer in coupled semiconductor quantum dots: We propose a solid-state implementation of stimulated Raman adiabatic passage\nin two coupled semiconductor quantum dots. Proper combination of two pulsed\nlaser fields allows the coherent carrier transfer between the two\nnanostructures without suffering significant losses due to environment\ncoupling. By use of a general solution scheme for the carrier states in the\ndouble-dot structure, we identify the pertinent dot and laser parameters.",
        "positive": "Adiabatic Green's function technique and the transient behavior in\n  time-dependent fermion-boson coupled models: The Lang-Firsov Hamiltonian, a well-known solvable model of interacting\nfermion-boson system with sideband features in the fermion spectral weight, is\ngeneralized to have the time-dependent fermion-boson coupling constant. We show\nhow to derive the two-time Green's function for the time-dependent problem in\nthe adiabatic limit, defined as the slow temporal variation of the coupling\nover the characteristic oscillator period. The idea we use in deriving the\nGreen's function is akin to the use of instantaneous basis states in solving\nthe adiabatic evolution problem in quantum mechanics. With such \"adiabatic\nGreen's function\" at hand we analyze the transient behavior of the spectral\nweight as the coupling is gradually tuned to zero. Time-dependent\ngeneralization of a related model, the spin-boson Hamiltonian, is analyzed in\nthe same way. In both cases the sidebands arising from the fermion-boson\ncoupling can be seen to gradually lose their spectral weights over time.\nConnections of our solution to the two-dimensional Dirac electrons coupled to\nquantized photons are discussed."
    },
    {
        "anchor": "Tunneling Anisotropic Magnetoresistance of Helimagnet Tunnel Junctions: We theoretically investigate the angular and spin dependent transport in\nnormal-metal/helical-multiferroic/ferromagnetic heterojunctions. We find a\ntunneling anisotropic magnetoresistance (TAMR) effect due to the spiral\nmagnetic order in the tunnel junction and to an effective spin-orbit coupling\ninduced by the topology of the localized magnetic moments in the multiferroic\nspacer.\n  The predicted TAMR effect is efficiently controllable by an external electric\nfield due to the magnetoelectric coupling.",
        "positive": "Capturing membrane structure and function in lattice Boltzmann models: We develop a mesoscopic approach to model the non-equilibrium behavior of\nmembranes at the cellular scale. Relying on lattice Boltzmann methods, we\ndevelop a solution procedure to recover the Nernst-Planck equations and Gauss's\nlaw. A general closure rule is developed to describe mass transport across the\nmembrane, which is able to account for protein-mediated diffusion based on a\ncoarse-grained representation. We demonstrate that our model is able to recover\nthe Goldman equation from first principles and show that hyper-polarization\noccurs when membrane charging dynamics are controlled by multiple relaxation\ntimescales. The approach provides a promising way to characterize\nnon-equilibrium behaviors that arise due to the role of membranes in mediating\ntransport based on realistic three-dimensional cell geometries."
    },
    {
        "anchor": "All optical Controlled-NOT quantum gate based on an exciton-polariton\n  circuit: We propose an implementation of a CNOT quantum gate for quantum computing\nbased on a patterned microcavity polariton system, which can be manufactured\nusing the modern technological facilities. The qubits are encoded in the spin\nof polaritons. The structure consists of two wire cavities oriented at 45\ndegrees with a micropillar between them. The polariton spin rotates due to the\nLongitudinal-Transverse splitting between polarisation eigenstates in the\nwires. In the pillar, the optically generated circularly polarised polariton\nmacrooccupied state plays the role of the control qubit. Because of the\nspin-anisotropic polariton interaction, it induces an effective magnetic field\nalong the Z-direction with a sign depending on the qubit value.",
        "positive": "Boundary-induced topological transition in an open SSH model: We consider a Su-Schrieffer-Heeger chain to which we attach a semi-infinite\nundimerized chain (lead) to both ends. We study the effect of the openness of\nthe SSH model on its properties. A representation of the infinite system using\nan effective Hamiltonian allows us to examine its low-energy states in more\ndetail. We show that, as one would expect, the topological edge states\nhybridize as the coupling between the systems is increased. As this coupling\ngrows, these states are suppressed, while a new type of edge state emerges from\nthe trivial topological phase. These new states, referred to as phase-inverted\nedge states, are localized low-energy modes very similar to the edge states of\nthe topological phase. Interestingly, localization occurs on a new shifted\ninterface, moving from the first (and last) site to the second (and second to\nlast) site. This suggests that the topology of the system is strongly affected\nby the leads, with three regimes of behavior. For very small coupling the\nsystem is in a well-defined topological phase; for very large coupling it is in\nthe opposite phase; in the intermediate region, the system is in a transition\nregime."
    },
    {
        "anchor": "Macroscopic quantum self-trapping and Josephson oscillations of\n  exciton-polaritons: A textbook example of quantum mechanical effects is the coupling of two\nstates through a tunnel barrier. In the case of macroscopic quantum states\nsubject to interactions, the tunnel coupling gives rise to Josephson phenomena\nincluding Rabi oscillations, the a.c. and d.c. effects, or macroscopic\nself-trapping depending on whether tunnelling or interactions dominate.\nNon-linear Josephson physics, observed in superfluid helium and atomic\ncondensates, has remained inaccessible in photonic systems due to the required\neffective photon-photon interactions. We report on the observation of\nnon-linear Josephson oscillations of two coupled polariton condensates confined\nin a photonic molecule etched in a semiconductor microcavity. By varying both\nthe distance between the micropillars forming the molecule and the condensate\ndensity in each micropillar, we control the ratio of coupling to interaction\nenergy. At low densities we observe coherent oscillations of particles\ntunnelling between the two micropillars. At high densities, interactions quench\nthe transfer of particles inducing the macroscopic self-trapping of the\ncondensate in one of the micropillars. The finite lifetime of polaritons\nresults in a dynamical transition from self-trapping to oscillations with pi\nphase. Our results open the way to the experimental study of highly non-linear\nregimes in photonic systems, such as chaos or symmetry-breaking bifurcations.",
        "positive": "Charge transport through graphene junctions with wetting metal leads: Graphene is believed to be an excellent candidate material for\nnext-generation electronic devices. However, one needs to take into account the\nnontrivial effect of metal contacts in order to precisely control the charge\ninjection and extraction processes. We have performed transport calculations\nfor graphene junctions with wetting metal leads (metal leads that bind\ncovalently to graphene) using nonequilibrium Green's functions and density\nfunctional theory. Quantitative information is provided on the increased\nresistance with respect to ideal contacts and on the statistics of current\nfluctuations. We find that charge transport through the studied two-terminal\ngraphene junction with Ti contacts is pseudo-diffusive up to surprisingly high\nenergies."
    },
    {
        "anchor": "Effective low energy Hamiltonians and unconventional Landau level\n  spectrum of monolayer C$_3$N: We derive a low-energy effective $\\mathbf{k}\\cdot\\mathbf{p}$ Hamiltonians for\nmonolayer C$_{3}$N at the $ \\Gamma $ and $ M $ points of the Brillouin zone\nwhere the band edge in the conduction and valence band can be found. Our\nanalysis of the electronic band symmetries helps to better understand several\nresults of recent ab-initio calculations[1,2] for the optical properties of\nthis material. We also calculate the Landau level spectrum. We find that the\nLandau level spectrum in the degenerate conduction bands at the $ \\Gamma $\npoint acquires properties that are reminiscent of the corresponding results in\nbilayer graphene, but there are important differences as well. Moreover,\nbecause of the heavy effective mass, $n$-doped samples may host interesting\nelectron-electron interaction effects.",
        "positive": "Coulomb drag in graphene near the Dirac point: We study Coulomb drag in double-layer graphene near the Dirac point. A\nparticular emphasis is put on the case of clean graphene, with transport\nproperties dominated by the electron-electron interaction. Using the quantum\nkinetic equation framework, we show that the drag becomes $T$-independent in\nthe clean limit, $T\\tau \\to \\infty$, where $T$ is temperature and $1/\\tau$\nimpurity scattering rate. For stronger disorder (or lower temperature), $T\\tau\n\\ll 1/\\alpha^2$, where $\\alpha$ is the interaction strength, the kinetic\nequation agrees with the leading-order ($\\alpha^2$) perturbative result. At\nstill lower temperatures, $T\\tau \\ll 1$ (diffusive regime) this contribution\ngets suppressed, while the next-order ($\\alpha^3$) contribution becomes\nimportant; it yields a peak centered at the Dirac point with a magnitude that\ngrows with lowering $T\\tau$."
    },
    {
        "anchor": "Microwave-assisted switching of a nanomagnet: analytical determination\n  of the optimal microwave field: We analytically determine the optimal microwave field that allows for the\nmagnetization reversal of a nanomagnet modeled as a macrospin. This is done by\nminimizing the total injected energy. The results are in good agreement with\nthe fields obtained numerically using the optimal control theory. For typical\nvalues of the damping parameter, a weak microwave field is sufficient to induce\nswitching through a resonant process. The optimal field is orthogonal to the\nmagnetization direction at any time and modulated both in amplitude and\nfrequency. The dependence of the pulse shape on the applied field and damping\nparameter is interpreted. The total injected energy is found to be\nproportionnal to the energy barrier between the initial state and the saddle\npoint and to the damping parameter. This result may be used as a means for\nprobing the damping parameter in real nanoparticles.",
        "positive": "Screening effects in a density functional theory based description of\n  molecular junctions in the Coulomb blockade regime: We recently introduced a method based on density functional theory (DFT) and\nnon-equilibrium Green's function techniques (NEGF) for calculating the addition\nenergies of single molecule nano-junctions in the Coulomb blockade (CB) regime.\nHere we apply this approach to benzene molecules lying parallel and at various\ndistances from two aluminum fcc (111) surfaces, and discuss the distance\ndependence in our calculations in terms of electrostatic screening effects. The\naddition energies near the surface are reduced by about a factor of two, which\nis comparable to previously reported calculations employing a computationally\nfar more demanding quasi-particle description."
    },
    {
        "anchor": "Phase-Coherent Charge Transport through a Porphyrin Nanoribbon: Quantum interference in nano-electronic devices could lead to reduced-energy\ncomputing and efficient thermoelectric energy harvesting. When devices are\nshrunk down to the molecular level it is still unclear to what extent electron\ntransmission is phase coherent, as molecules usually act as scattering centres,\nwithout the possibility of showing particle-wave duality. Here we show electron\ntransmission remains phase coherent in molecular porphyrin nanoribbons,\nsynthesized with perfectly defined geometry, connected to graphene electrodes.\nThe device acts as a graphene Fabry-P\\'erot interferometer, allowing direct\nprobing of the transport mechanisms throughout several regimes, including the\nKondo one. Electrostatic gating allows measurement of the molecular conductance\nin multiple molecular oxidation states, demonstrating a thousand-fold increase\nof the current by interference, and unravelling molecular and graphene\ntransport pathways. These results demonstrate a platform for the use of\ninterferometric effects in single-molecule junctions, opening up new avenues\nfor studying quantum coherence in molecular electronic and spintronic devices.",
        "positive": "Tomography of Majorana Fermions with STM Tips: We investigate numerically the possibility to detect the spatial profile of\nMajorana fermions (MFs) modeling STM tips that are made of either normal or\nsuperconducting material. In both cases, we are able to resolve the\nlocalization length and the oscillation period of the MF wavefunction. We show\nthat the tunneling between the substrate and the tip, necessary to get the\ninformation on the wave function oscillations, has to be smaller in the case of\na superconducting STM. In the strong tunneling regime, the differential\nconductance saturates making it more difficult to observe the exponential decay\nof MFs. The temperature broadening of the profile is strongly suppressed in\ncase of the superconducting lead resulting, generally, in better resolution."
    },
    {
        "anchor": "Conductance of a quantum point contact in the presence of spin-orbit\n  interaction: A recursive Green's function technique is developed to calculate the\nspin-dependent conductance in mesoscopic structures. Using this technique, we\nstudy the spin-dependent electronic transport of quantum point contacts in the\npresence of the Rashba spin-orbit interaction. We observed that some\noscillations in the `quantized' conductance are induced by the spin-orbit\ninteraction, and indicated that the oscillations may stem from the spin-orbit\ncoupling associated multiple reflections. It is also indicated that the 0.7\nstructure of the conductance observed in mesoscopic experiments would not stem\nfrom the spin-orbit interaction.",
        "positive": "Lasing in topological edge states of a 1D lattice: Topology describes properties that remain unaffected by smooth distortions.\nIts main hallmark is the emergence of edge states localized at the boundary\nbetween regions characterized by distinct topological invariants. This feature\noffers new opportunities for robust trapping of light in nano- and micro-meter\nscale systems subject to fabrication imperfections and to environmentally\ninduced deformations. Here we show lasing in such topological edge states of a\none-dimensional lattice of polariton micropillars that implements an orbital\nversion of the Su-Schrieffer-Heeger Hamiltonian. We further demonstrate that\nlasing in these states persists under local deformations of the lattice. These\nresults open the way to the implementation of chiral lasers in systems with\nbroken time-reversal symmetry and, when combined with polariton interactions,\nto the study of nonlinear topological photonics."
    },
    {
        "anchor": "Two-electron resonances in quasi-one dimensional quantum dots with\n  Gaussian confinement: We consider a quasi one-dimensional quantum dot composed of two Coulombically\ninteracting electrons confined in a Gaussian trap. Apart from bound states, the\nsystem exhibits resonances that are related to the autoionization process.\nEmploying the complex-coordinate rotation method, we determine the resonance\nwidths and energies and discuss their dependence on the longitudinal\nconfinement potential and the lateral radius of the quantum dot. The stability\nproperties of the system are discussed.",
        "positive": "Coherent Population Trapping in Diamond N-V Centers at Zero Magnetic\n  Field: Coherent population trapping at zero magnetic field was observed for\nnitrogen-vacancy centers in diamond under optical excitation. This was measured\nas a reduction in photoluminescence when the detuning between two excitation\nlasers matched the 2.88 GHz crystal-field splitting of the color center ground\nstates. This behavior is highly sensitive to strain, which modifies the excited\nstates, and was unexpected following recent experiments demonstrating optical\nreadout of single nitrogen-vacancy electron spins based on cycling transitions.\nThese results demonstrate for the first time that three-level Lambda\nconfigurations suitable for proposed quantum information applications can be\nrealized simultaneously for all four orientations of nitrogen-vacancy centers\nat zero magnetic field."
    },
    {
        "anchor": "If graphynes turn into graphene: the thermal stability study: The thermal stability of $\\alpha$-, $\\beta$-, 6,6,12-graphyne and graphdiyne\nwas studied by a statistic model, which was seriously tested by classical\nmolecular dynamics simulations. By first-principles calculations of related\npotential energy curves, the model predicts that all the lifetime of\nfree-standing single layer graphynes considered is more than 10$^{44}$ years at\nroom temperature. When the temperature gets up to 1000 K, they are still very\nstable, but quickly turn into graphene if the temperature is about 2000 K",
        "positive": "Understanding Hot-Electron Generation and Plasmon Relaxation in Metal\n  Nanocrystals: Quantum and Classical Mechanisms: Generation of energetic (hot) electrons is an intrinsic property of any\nplasmonic nanostructure under illumination. Simultaneously, a striking\nadvantage of metal nanocrystals over semiconductors lies in their very large\nabsorption cross sections. Therefore, metal nanostructures with strong and\ntailored plasmonic resonances are very attractive for photocatalytic\napplications. However, the central questions regarding plasmonic hot electrons\nare how to quantify and extract the optically-excited energetic electrons in a\nnanocrystal. We develop a theory describing the generation rates and the\nenergy-distributions of hot electrons in nanocrystals with various geometries.\nIn our theory, hot electrons are generated owing to surfaces and hot spots. The\nformalism predicts that large optically-excited nanocrystals show the\nexcitation of mostly low-energy Drude electrons, whereas plasmons in small\nnanocrystals involve mostly hot electrons. The energy distributions of\nelectrons in an optically-excited nanocrystal show how the quantum many-body\nstate in small particles evolves towards the classical state described by the\nDrude model when increasing nanocrystal size. We show that the rate of surface\ndecay of plasmons in nanocrystals is directly related to the rate of generation\nof hot electrons. Based on a detailed many-body theory involving kinetic\ncoefficients, we formulate a simple scheme describing the plasmon's dephasing.\nIn most nanocrystals, the main decay mechanism of a plasmon is the Drude\nfriction-like process and the secondary path comes from generation of hot\nelectrons due to surfaces and electromagnetic hot spots. This latter path\nstrongly depends on the size, shape and material of the nanocrystal,\ncorrespondingly affecting its efficiency of hot-electron production. The\nresults in the paper can be used to guide the design of plasmonic nanomaterials\nfor photochemistry and photodetectors."
    },
    {
        "anchor": "Influence of the charge carrier tunneling processes on the recombination\n  dynamics in single lateral quantum dot molecules: We report on the charge carrier dynamics in single lateral quantum dot\nmolecules and the effect of an applied electric field on the molecular states.\nControllable electron tunneling manifests itself in a deviation from the\ntypical excitonic decay behavior which is strongly influenced by the tuning\nelectric field and inter-molecular Coulomb energies. A rate equation model is\ndeveloped to gain more insight into the charge transfer and tunneling\nmechanisms. Non-resonant (phonon-mediated) electron tunneling which changes the\nmolecular exciton character from direct to indirect, and vice versa, is found\nto be the dominant tunable decay mechanism of excitons besides radiative\nrecombination.",
        "positive": "Hall Coefficient and electron-electron interaction of 2D electrons in\n  Si-MOSFET's: Recent experiments in silicon MOSFETs indicate that the Hall coefficient is\nindependent of magnetic field applied at a small angle with respect to the\nplane. Below a scattering between spin-up and spin-down carriers is considered\nto be the main reason for the experimental observation. Comparison of two band\nmodel with experiment provides an upper limit for the electron-electron\nscattering time $\\tau_{ee}$ in the dilute 2D electron system as a function of\nelectron density $n_s$. The time $\\tau_{ee}$ increases gradually with $n_s$,\nbecoming much greater than the transport scattering time $\\tau_p$ for densities\n$n_s>4 \\times 10 ^{11}$ cm$^{-2}$. Strong electron-electron scattering is found\nfor $1.22 \\times 10 ^{11} <n_s<3 \\times 10 ^{11}$ cm$^{-2}$, the region which\nis near to the apparent metal insulator transition."
    },
    {
        "anchor": "Nonlinear photoluminescence in gold thin films: Promising applications in photonics are driven by the ability to fabricate\ncrystal-quality metal thin films of controlled thickness down to a few\nnanometers. In particular, these materials exhibit a highly nonlinear response\nto optical fields owing to the induced ultrafast electron dynamics, which is\nhowever poorly understood on such mesoscopic length scales. Here, we reveal a\nnew mechanism that controls the nonlinear optical response of thin metallic\nfilms, dominated by ultrafast electronic heat transport when the thickness is\nsufficiently small. By experimentally and theoretically studying electronic\ntransport in such materials, we explain the observed temporal evolution of\nphotoluminescence in pump-probe measurements that we report for crystalline\ngold flakes. Incorporating a first-principles description of the electronic\nband structures, we model electronic transport and find that ultrafast thermal\ndynamics plays a pivotal role in determining the strength and time-dependent\ncharacteristics of the nonlinear photoluminescence signal, which is largely\ninfluenced by the distribution of hot electrons and holes, subject to diffusion\nacross the film as well as relaxation to lattice modes. Our findings introduce\nconceptually novel elements triggering the nonlinear optical response of\nnanoscale materials while suggesting additional ways to control and leverage\nhot carrier distributions in metallic films.",
        "positive": "Inter-Band Effects of Magnetic Field on Hall Conductivity in Multi\n  Layered Massless Dirac Fermion System $\u03b1$-(BEDT-TTF)$_2$I$_3$: We have discovered two-dimensional zero-gap material with a layered structure\nin the organic conductor $\\alpha$-(BEDT-TTF)$_2$I$_3$ under high hydrostatic\npressure. In contrast to graphene, the electron-hole symmetry is not good\nexcept at the vicinity of the Dirac points. Thus, temperature dependence of the\nchemical potential, $\\mu$, plays an important role in the transport in this\nsystem. The experimental formula of $\\mu$ is revealed. We succeeded in\ndetecting the inter-band effects of a magnetic field on the Hall conductivity\nwhen $\\mu$ passes the Dirac point."
    },
    {
        "anchor": "Electron teleportation between quantum dots using virtual dark exciton: We here propose a mechanism to teleport electrons between quantum dots\nthrough the transformation of a virtual bright exciton into a dark exciton.\nThis mechanism relies on the interactions of two composite bosons: a pair of\nelectrons with opposite spins, trapped in two dots and an electron-hole pair in\na free exciton coupled to an unabsorbed pump pulse, which makes it ``bright''\nbut virtual. This bright exciton first turns ``dark'' by dropping its electron\nand stealing the trapped electron with opposite spin through an exchange\nCoulomb process with the trapped pair. In a second step, the dark exciton\n``flies'' with its electron to the other dot where it turns bright again, by\nthe inverse process. The ``Shiva diagrams'' for composite boson many-body\neffects that we have recently introduced, enlighten this understanding.",
        "positive": "Anisotropic exceptional points of arbitrary order: A pair of anisotropic exceptional points (EPs) of arbitrary order are found\nin a class of non-Hermitian random systems with asymmetric hoppings. Both\neigenvalues and eigenvectors exhibit distinct behaviors when these anisotropic\nEPs are approached from two orthogonal directions in the parameter space. For\nan order-$N$ anisotropic EP, the critical exponents $\\nu$ of phase rigidity are\n$(N-1)/2$ and $N-1$, respectively. These exponents are universal within the\nclass. The order-$N$ anisotropic EPs split and trace out multiple ellipses of\nEPs of order $2$ in the parameter space. For some particular configurations,\nall the EP ellipses coalesce and form a ring of EPs of order $N$. Crossover to\nthe conventional order-$N$ EPs with $\\nu=(N-1)/N$ is discussed."
    },
    {
        "anchor": "Non equilibrium anisotropic excitons in atomically thin ReS$_2$: We present a systematic investigation of the electronic properties of bulk\nand few layer ReS$_2$ van der Waals crystals using low temperature optical\nspectroscopy. Weak photoluminescence emission is observed from two\nnon-degenerate band edge excitonic transitions separated by $\\sim$ 20 meV. The\ncomparable emission intensity of both excitonic transitions is incompatible\nwith a fully thermalized (Boltzmann) distribution of excitons, indicating the\nhot nature of the emission. While DFT calculations predict bilayer ReS$_2$ to\nhave a direct fundamental band gap, our optical data suggests that the\nfundamental gap is indirect in all cases.",
        "positive": "Topology in the Sierpi\u0144ski-Hofstadter problem: Using the Sierpi\\'nski carpet and gasket, we investigate whether fractal\nlattices embedded in two-dimensional space can support topological phases when\nsubjected to a homogeneous external magnetic field. To this end, we study the\nlocalization property of eigenstates, the Chern number, and the evolution of\nenergy level statistics when disorder is introduced. Combining these\ntheoretical tools, we identify regions in the phase diagram of both the carpet\nand the gasket, for which the systems exhibit properties normally associated to\ngapless topological phases with a mobility edge."
    },
    {
        "anchor": "Magnetic field asymmetry of mesocopic dc rectification in Aharonov Bohm\n  rings: Fundamental Casimir-Onsager symmetry rules for linear response do not apply\nto non linear transport. This motivates the investigation of nonlinear dc\nconductance of mesoscopic GaAs/GaAlAs rings in a 2 wire configuration. The\nsecond order current response to a potential bias is of particular interest. It\nis related to the sensitivity of conductance fluctuations to this bias and\ncontains information on electron interactions not included in the linear\nresponse. In contrast with the linear response which is a symmetric function of\nmagnetic field we find that this second order response exhibits a field\ndependence which contains an antisymmetric part. We analyse the flux periodic\nand aperiodic components of this asymmetry and find that they only depend on\nthe conductance of the rings which is varied by more than an order of\nmagnitude. These results are in good agreement with recent theoretical\npredictions relating this asymmetric response to the electron interactions.",
        "positive": "Many-body radiative heat transfer theory: In this Letter a N-body theory for the radiative heat exchange in thermally\nnon equilibrated discrete systems of finite size objects is presented. We\nreport strong exaltation effects of heat flux which can be explained only by\ntaking into account the presence of many body interactions. Our theory extends\nthe standard Polder and van Hove stochastic formalism used to evaluate heat\nexchanges between two objects isolated from their environment to a collection\nof objects in mutual interaction. It gives a natural theoretical framework to\ninvestigate the photon heat transport properties of complex systems at\nmesoscopic scale."
    },
    {
        "anchor": "Quantum Hall Effect induced by electron-electron interaction in\n  disordered GaAs layers with 3D spectrum: It is shown that the observed Quantum Hall Effect in epitaxial layers of\nheavily doped n-type GaAs with thickness (50-140 nm) larger the mean free path\nof the conduction electrons (15-30 nm) and, therefore, with a three-dimensional\nsingle-particle spectrum is induced by the electron-electron interaction. The\nHall resistance R_xy of the thinnest sample reveals a wide plateau at small\nactivation energy E_a=0.4 K found in the temperature dependence of the\ntransverse resistance R_xx. The different minima in the transverse conductance\nG_xx of the different samples show a universal temperature dependence\n(logarithmic in a large range of rescaled temperatures T/T_0) which is\nreminiscent of electron-electron-interaction effects in coherent diffusive\ntransport.",
        "positive": "Odd- and even-denominator fractional quantum Hall states in monolayer\n  WSe$_2$: Monolayer (ML) semiconducting transition-metal dichalcogenides (TMDs)\nrepresent a unique class of two-dimensional (2D) electron systems. Their\natomically thin structure -- just like graphene -- facilitates gate-tunability,\nwhile the sizable band gap and strong spin-orbit coupling hold promise for\nproperties beyond graphene. Measurements under large magnetic fields have\nrevealed an unusual LL structure, distinct from other 2D electron systems.\nHowever, owing to limited sample quality and poor electrical contact, probing\nthe lowest Landau levels (LLs) has been challenging, and observation of\nelectron correlations within the fractionally filled LLs regime has not been\npossible. Here, through bulk electronic compressibility measurements, we\ninvestigate the LL structure of ML WSe$_2$ in the extreme quantum limit, and\nobserve fractional quantum Hall (FQH) states in the lowest three LLs. The\nodd-denominator FQH sequences demonstrate a systematic evolution with the LL\norbital index, which has not been observed in any other system but is\nconsistent with generic theoretical expectations. In addition, we observe an\neven-denominator state in the second LL that is expected to host non-Abelian\nstatistics. Our results suggest that the 2D semiconductors can provide an\nexperimental platform that closely resembles idealized theoretical models in\nthe quantum Hall regime."
    },
    {
        "anchor": "Effect of dephasing on the current through a periodically driven quantum\n  point contact: We consider two one-dimensional quantum $XX$ magnets linked by a periodically\ndriven quantum point contact (QPC). If magnets are initially polarized in\nopposite directions, one expects that a spin current through the QPC will\nestablish. It has been shown recently [Phys. Rev. B 103, L041405 (2021)] that,\nin fact, when the driving frequency exceeds a critical value, the current halts\ncompletely, the QPC being effectively insulating. Here we enquire how this\npicture is affected by quantum dephasing. Our findings reveal that any non-zero\ndephasing restores the current.",
        "positive": "Phonon engineering with superlattices: generalized nanomechanical\n  potentials: Earlier implementations to simulate coherent wave propagation in\none-dimensional potentials using acoustic phonons with gigahertz-terahertz\nfrequencies were based on coupled nanoacoustic resonators. Here, we generalize\nthe concept of adiabatic tuning of periodic superlattices for the\nimplementation of effective one-dimensional potentials giving access to cases\nthat cannot be realized by previously reported phonon engineering approaches,\nin particular the acoustic simulation of electrons and holes in a quantum well\nor a double well potential. In addition, the resulting structures are much more\ncompact and hence experimentally feasible. We demonstrate that potential\nlandscapes can be tailored with great versatility in these multilayered\ndevices, apply this general method to the cases of parabolic, Morse and\ndouble-well potentials and study the resulting stationary phonon modes. The\nphonon cavities and potentials presented in this work could be probed by\nall-optical techniques like pump-probe coherent phonon generation and Brillouin\nscattering."
    },
    {
        "anchor": "Energy storage in magnetic textures driven by vorticity flow: An experimentally feasible energy-storage concept is formulated based on\nvorticity (hydro)dynamics within an easy-plane insulating magnet. The free\nenergy, associated with the magnetic winding texture, is built up in a circular\neasy-plane magnetic structure by injecting a vorticity flow in the radial\ndirection. The latter is accomplished by electrically induced spin-transfer\ntorque, which pumps energy into the magnetic system in proportion to the vortex\nflux. The resultant magnetic metastable state with a finite winding number can\nbe maintained for a long time because the process of its relaxation via phase\nslips is exponentially suppressed when the temperature is well below the Curie\ntemperature. We propose to characterize the vorticity-current interaction\nunderlying the energy-loading mechanism through its contribution to the\neffective electric inductance in the rf response. Our proposal may open an\navenue for naturally powering spintronic circuits and nontraditional\nmagnet-based neuromorphic networks.",
        "positive": "Measurement of the Current-Phase Relation in Josephson Junctions Rhombi\n  Chains: We present low temperature transport measurements in one dimensional\nJosephson junctions rhombi chains. We have measured the current phase relation\nof a chain of 8 rhombi. The junctions are either in the classical phase regime\nwith the Josephson energy much larger than the charging energy, $E_{J}\\gg\nE_{C}$, or in the quantum phase regime where $E_{J}/E_{C}\\approx 2$. In the\nstrong Josephson coupling regime ($E_{J}\\gg E_{C} \\gg k_{B}T$) we observe a\nsawtooth-like supercurrent as a function of the phase difference over the\nchain. The period of the supercurrent oscillations changes abruptly from one\nflux quantum $\\Phi_{0}$ to half the flux quantum $\\Phi_{0}/2$ as the rhombi are\ntuned in the vicinity of full frustration. The main observed features can be\nunderstood from the complex energy ground state of the chain. For\n$E_{J}/E_{C}\\approx 2$ we do observe a dramatic suppression and rounding of the\nswitching current dependence which we found to be consistent with the model\ndeveloped by Matveev et al.(Phys. Rev. Lett. {\\bf 89}, 096802(2002)) for long\nJosephson junctions chains."
    },
    {
        "anchor": "Effective Land\u00e9 factors for an electrostatically defined quantum\n  point contact in silicene: The transconductance and effective Land\\'{e} $g^*$ factors for a quantum\npoint contact defined in silicene by the electric field of a split gate is\ninvestigated. The strong spin-orbit coupling in buckled silicene reduces the\n$g^*$ factor for in-plane magnetic field from the nominal value 2 to around 1.2\nfor the first- to 0.45 for the third conduction subband. However, for\nperpendicular magnetic field we observe an enhancement of $g^*$ factors for the\nfirst subband to 5.8 in nanoribbon with zigzag and to 2.5 with armchair edge.\nThe main contribution to the Zeeman splitting comes from the intrinsic\nspin-orbit coupling defined by the Kane-Mele form of interaction.",
        "positive": "Nanoscale Probing of Broken-Symmetry States in Graphene Induced by\n  Individual Atomic Impurities: Inherent symmetries of a system lead to multiple degeneracies of its energy\nspectra. Introducing individual atomic impurities can locally break these\nsymmetries, which is expected to lift the degenerate degrees of freedom around\nthe impurities. Although central to our understanding of the fundamental\nproperties of solids, the broken-symmetry states induced by individual atomic\nimpurities have so far eluded observation. Here, we report nanoscale probing of\nthe broken-symmetry states in graphene induced by two types of individual\natomic impurities, i.e., isolated nitrogen dopants and isolated hydrogen atoms\nchemisorbed on graphene. Our experiments demonstrate that both types of atomic\nimpurities can locally break sublattice symmetry of graphene and generate\nvalley-polarized states, which extends several nanometers around the\nimpurities. For the isolated hydrogen atom chemisorbed on graphene, the\nenhanced spin-orbit coupling, which arises from the sp3 distortion of graphene\ndue to the hydrogen chemisorption, further lifts the spin degeneracy, resulting\nin a fully spin and valley polarized states within about 1 nm around the\nhydrogen atom. Our result paves the way to control various broken-symmetry\nstates at the nanoscale by various atomic impurities."
    },
    {
        "anchor": "Phenomenological modeling of long range noncontact friction in micro-\n  and nanoresonators: Motivated by the results of an experiment using atomic force microscopy\nperformed by Gotsmann and Fuchs [Phys. Rev. Lett. {\\bf 86}, 2597 (2001)], where\na strong energy loss due to the tip-sample interaction was measured, we\ninvestigate the potential implications of this energy loss channel to the\nquality factor of suspended micro- and nanoresonators. Because the observed\ntip-sample dissipation remains without a satisfactory theoretical explanation,\ntwo phenomenological models are proposed to generalize the experimental\nobservations. A minimal phenomenological model simply extends for larger\nseparations the range of validity of the power law found experimentally for the\ndamping coefficient. A more elaborate phenomenological model assumes that the\nnoncontact friction is a consequence of the Casimir force acting between the\nclosely spaced surfaces. Both models provide quantitative results for the\nnoncontact friction between any two objects which are then used to estimate the\nenergy loss for suspended bar micro- and nanoresonators. Its is concluded that\nthe energy loss due to the unknown mechanism has the potential to seriously\nrestrict the quality factor of both micro- and nanoresonators.",
        "positive": "Temperature Measurement Based on Electron Spin Resonance of Magnetic\n  Nanoparticles: Magnetic nanoparticles (MNPs) have excellent magnetic-temperature\ncharacteristic. However, current temperature measurement based on MNPs is\ninterfered by concentration. Utilizing the electron spin resonance (ESR), we\npropose a highly sensitive temperature measurement method without concentration\ncoupling. The anisotropic field is affected by temperature, thus affecting the\ng-value. The influence of the MNP concentration, size, and the data analysis\nmethod on temperature estimation are studied. The optimal temperature\nsensitivity is achieved with 15-nm MNPs while Gaussian smoothing method allows\nan optimal accuracy at Fe concentration of 5 mg/ml with a root mean squared\nerror of 0.07 K."
    },
    {
        "anchor": "Cascade of electronic transitions in magic-angle twisted bilayer\n  graphene: Magic-angle twisted bilayer graphene (MATBG) exhibits a rich variety of\nelectronic states, including correlated insulators, superconductors, and\ntopological phases. Understanding the microscopic mechanisms responsible for\nthese phases requires determining the interplay between electron-electron\ninteractions and quantum degeneracy due to spin and valley degrees of freedom.\nSignatures of strong electron-electron correlations have been observed at\npartial fillings of the flat electronic bands in recent spectroscopic\nmeasurements. Transport experiments have shown changes in the Landau level\ndegeneracy at fillings corresponding to an integer number of electrons per\nmoir\\'e unit cell. However, the interplay between interaction effects and the\ndegeneracy of the system is currently unclear. Using high-resolution scanning\ntunneling microscopy (STM), we observed a cascade of transitions in the\nspectroscopic properties of MATBG as a function of electron filling. We find\ndistinct changes in the chemical potential and a rearrangement of the\nlow-energy excitations at each integer filling of the moir\\'e flat bands. These\nspectroscopic features are a direct consequence of Coulomb interactions, which\nsplit the degenerate flat bands into Hubbard sub-bands. We find these\ninteractions, the strength of which we can extract experimentally, to be\nsurprisingly sensitive to the presence of a perpendicular magnetic field, which\nstrongly modifies the spectroscopic transitions. The cascade of transitions we\nreport here characterizes the correlated high-temperature parent phase from\nwhich various insulating and superconducting ground-state phases emerge at low\ntemperatures in MATBG.",
        "positive": "Revealing giant exciton fine-structure splitting in 2D perovskites using\n  van der Waals passivation: The study of two-dimensional (2D) van der Waals materials has been an active\nfield of research in the development of new optoelectronics and photonic\napplications over the last decade. Organic-inorganic layered perovskites are\ncurrently some of the most promising 2D van der Waals materials, due to their\nexceptional optical brightness and enhanced excitonic effects. However, low\ncrystal quality and spectral diffusion usually broaden the exciton linewidth,\nobscuring the fine structure of the exciton in conventional photoluminescence\nexperiments. Here, we propose a mechanical approach for reducing the effect of\nspectral diffusion by means of hBN-capping on layered perovskites with\ndifferent thicknesses, revealing the exciton fine structure. We used a\nstochastic model to link the reduction of the spectral linewidth with the\npopulation of active charge fluctuation centres present in the organic spacer\ntaking part in the dynamical Stark shift. Active fluctuation centres are\nreduced by a factor of 3.7 to 7.1 when we include hBN-capping according to our\ndirect spectral measurements. This rate is in good agreement with the analysis\nof the overlap between the squared perovskite lattice and the hexagonal hBN\nlattice. Van der Waals forces between both lattices cause the partial clamping\nof the perovskite organic spacer molecules, and hence, the amplitude of the\ndynamical Stark shift characteristic of the spectral diffusion effect is\nreduced. Our work provides an easy and low-cost solution to the problem of\naccessing important fine-structure excitonic state information, along with an\nexplanation of the important carrier dynamics present in the organic spacer\nthat affect the quality of the optical emission."
    },
    {
        "anchor": "Limitation of electron mobility from hyperfine interaction in\n  ultra-clean quantum wells and topological insulators: The study of electron transport and scattering processes limiting electron\nmobility in high-quality semiconductor structures is central to solid-state\nelectronics. Here, we uncover an unavoidable source of electron scattering\nwhich is caused by fluctuations of nuclear spins. We calculate the momentum\nrelaxation time of electrons in quantum wells governed by the hyperfine\ninteraction between electrons and nuclei and show that this time drastically\ndepends on the spatial correlation of nuclear spins. Moreover, the scattering\nprocesses accompanied by a spin flip are a source of the backscattering of\nDirac fermions at conducting surfaces of topological insulators.",
        "positive": "Quantum Shape Effects: Can we change the shape of a domain without altering its sizes? By\nintroducing a size-invariant shape transformation, we propose the existence and\nexplore the consequences of a new type of physical effect appearing at the\nquantum scales, which we call here as \"quantum shape effect\". By completely\nseparating the shape effects from size effects, we show that shape alone\nbecomes a control parameter on the thermodynamic state functions of confined\nsystems at nanoscale. We develop an overlapped quantum boundary layer method to\nanalytically predict the quantum shape effects, reducing a thermodynamic\nproblem into a geometric one and revealing the profound link between the\ngeometry and thermodynamics at the quantum scales. Furthermore, we introduce\nthe isoformal, shape preserving, process which opens up the possibility of a\nnew generation of thermodynamic cycles operating at nanoscale with unique\nfeatures. As a whole, this thesis constitutes the proposition and a\ncomprehensive investigation of the theory, construction of the methodology and\nexploration of the applications of quantum shape effects in thermodynamics."
    },
    {
        "anchor": "Laser-like vibrational instability in rectifying molecular conductors: We study the damping of molecular vibrations due to electron-hole pair\nexcitations in donor-acceptor(D-A) type molecular rectifiers. At finite voltage\nadditional non-equilibrium electron-hole pair excitations involving both\nelectrodes become possible, and contribute to the stimulated emission and\nabsorption of phonons. We point out a generic mechanism for D-A molecules,\nwhere the stimulated emission can dominate beyond a certain voltage due to\ninverted position of the D and A quantum resonances. This leads to\ncurrent-driven amplification (negative damping) of the phonons similar to\nlaser-action. We investigate the effect in realistic molecular rectifier\nstructures using first principles calculations.",
        "positive": "Statistical interactions and boson-anyon duality in fractional quantum\n  Hall fluids: We present an exact scheme of bosonization for anyons (including fermions) in\nthe two-dimensional manifold of the quantum Hall fluid. This gives every\nfractional quantum Hall phase of the electrons one or more dual bosonic\ndescriptions. For interacting electrons, the statistical transmutation from\nanyons to bosons allows us to explicitly derive the microscopic statistical\ninteraction between the anyons, in the form of the effective two-body and\nfew-body interactions. This also leads to a number of unexpected topological\nphases of the single component bosonic fractional quantum Hall effect that may\nbe experimentally accessible. Numerical analysis of the energy spectrum and\nground state entanglement properties are carried out for simple examples."
    },
    {
        "anchor": "Exchange effects on electron transport through single-electron\n  spin-valve transistors: We study electron transport through single-electron spin-valve transistors in\nthe presence of non-local exchange between the ferromagnetic leads and the\ncentral normal-metal island. The Coulomb interaction is described with the\northodox model for Coulomb blockade and we allow for noncollinear lead\nmagnetization directions. Two distinct exchange mechanisms that have been\ndiscussed in the literature are shown to be of comparable strength and are\ntaken into account on equal footing. We present results for the linear\nconductance as a function of gate voltage and magnetic configuration, and\ndiscuss the response of the system to applied magnetic fields.",
        "positive": "Electroluminescence as a probe of strong exciton-plasmon coupling in\n  few-layer WSe2: The manipulation of coupled quantum excitations is of fundamental importance\nin realizing novel photonic and optoelectronic devices. We use\nelectroluminescence to probe plasmon-exciton coupling in hybrid structures\nconsisting of a nanoscale plasmonic tunnel junction and few-layer\ntwo-dimensional transition-metal dichalcogenide transferred onto the junction.\nThe resulting hybrid states act as a novel dielectric environment that affects\nthe radiative recombination of hot carriers in the plasmonic nanostructure. We\ndetermine the plexcitonic spectrum from the electroluminescence and find Rabi\nsplittings exceeding 50 meV in strong coupling regime. Our experimental\nfindings are supported by electromagnetic simulations that enable us to explore\nsystematically, and in detail, the emergence of plexciton polaritons as well as\nthe polarization characteristics of their far-field emission.\nElectroluminescence modulated by plexciton coupling provides potential\napplications for engineering compact photonic devices with tunable optical and\nelectrical properties."
    },
    {
        "anchor": "Interaction Effects in a One-Dimensional Constriction: We have investigated the transport properties of one-dimensional (1D)\nconstrictions defined by split-gates in high quality GaAs/AlGaAs\nheterostructures. In addition to the usual quantized conductance plateaus, the\nequilibrium conductance shows a structure close to $0.7(2e^2/h)$, and in\nconsolidating our previous work [K.~J. Thomas et al., Phys. Rev. Lett. 77, 135\n(1996)] this 0.7 structure has been investigated in a wide range of samples as\na function of temperature, carrier density, in-plane magnetic field\n$B_{\\parallel}$ and source-drain voltage $V_{sd}$. We show that the 0.7\nstructure is not due to transmission or resonance effects, nor does it arise\nfrom the asymmetry of the heterojunction in the growth direction. All the 1D\nsubbands show Zeeman splitting at high $B_{\\parallel}$, and in the wide channel\nlimit the $g$-factor is $\\mid g \\mid \\approx 0.4$, close to that of bulk GaAs.\nAs the channel is progressively narrowed we measure an exchange-enhanced\n$g$-factor. The measurements establish that the 0.7 structure is related to\nspin, and that electron-electron interactions become important for the last few\nconducting 1D subbands.",
        "positive": "Current noise and Keldysh vertex function of an Anderson impurity in the\n  Fermi liquid regime: We present a complete microscopic Fermi-liquid description for\nnext-to-leading order transport through an Anderson impurity under a finite\nbias voltage $V$. It is applicable to multilevel quantum dots without\nparticle-hole or time-reversal symmetry, and is constructed based on the\nnonequilibrium Keldysh formalism, taking into account the current conservation\nbetween electrons in the impurity levels and the conduction bands.\nSpecifically, we derive the formula for the current noise generated in the\nsteady flow up to terms of order $(eV)^3$ at zero temperature $T=0$. To this\nend, we calculate the Keldysh vertex functions\n$\\Gamma_{\\sigma\\sigma';\\sigma'\\sigma}^{ \\nu_1\\nu_2;\\nu_3\\nu_4} (\\omega,\\omega';\n\\omega',\\omega)$, which depend on branches $\\nu_1, \\nu_2, \\nu_3$ and $\\nu_4$ of\nthe time-loop contour and on spin degrees of freedom $\\sigma$ and $\\sigma'$, up\nto linear-order terms with respect to $eV$, $T$, and frequencies $\\omega$ and\n$\\omega'$. The coefficients of these linear-order terms are determined by a set\nof the parameters, defined with respect to the equilibrium ground state: the\nphase shift, static susceptibilities, and nonlinear three-body susceptibilities\nof the impurity electrons. The low-energy expressions of the vertex components\nare shown to satisfy the Ward identities with the Keldysh Green's functions\nexpanded up to terms of order $\\omega^2$, $(eV)^2$, and $T^2$. We also find\nthat the imaginary part of the Ward identities can be described in terms of the\n$eV$-dependent collision integrals for a single-quasiparticle excitation and\nthat for a single quasiparticle-quasihole pair excitation. These collision\nintegrals ensure the current conservation of the next-to-leading order\nFermi-liquid transport due to the quasiparticles with a finite damping rate."
    },
    {
        "anchor": "Role of strain in interacting silicon nanoclusters: The possibility of controlling the optical transition probability between\nneighbouring silicon nanoclusters (Si-NCs) constitutes nowadays an attractive\nprospect in nanophotonics and photovoltaics. In this work, by means of\ntheoretical ab-initio calculations we investigate the effect of strain on the\nopto-electronic properties of Si-NCs pairs. We consider two sources of strain:\nthe strain induced by an embedding SiO2 matrix, and the strain generated by\nmutual NC-NC forces occurring at small distances. Independently on its source,\nwe observe a fundamental impact of the strain on the orbitals localization and,\nas a consequence, on the transition probability between energy states,\nbelonging or not to the same NC. The resulting picture allots to the structural\nstrain a fundamental role in the NC-NC interaction mechanisms, suggesting the\npossibility of enabling a strain-controlled response in Si-NC ensambles.",
        "positive": "The composite fermion model of quantum Hall effect is internally\n  inconsistent: The The composite fermion model (CF) of the quantum Hall effect which gives\nthe correct series of charges is based on attachment of flux quanta to the\nelectron. The construction of the series of charges leads to a field expression\nwhich requires that flux quanta are attached to the electron. The series based\non the experimental data is correct but the field deduced from such a series is\nfound to be incorrect. The attachment of even number of flux quanta to an\nelectron required by the CF model is found to be internally inconsistent."
    },
    {
        "anchor": "Robustness of vorticity in electron fluids: Vortices in electron fluids attract interest as a potential smoking-gun\neffect of electron hydrodynamics. However, a general framework that would allow\nto relate vorticity measured at macroscales and the microscopic mechanisms of\ninteraction and scattering has so far been lacking. We demonstrate that\nvorticity originates in a robust manner from a nonlocal conductivity response\n$\\sigma(k)$, no matter what origin. This connection renders vorticity a\nproperty transcending boundaries between different phases. We compare the\nbehavior in the hydrodynamic and ballistic phases in a realistic geometry,\nfinding vorticity values that are similar in both phases. Interestingly,\nhydrodynamic vortices are orders-of-magnitude more sensitive to the presence of\nmomentum-relaxing scattering than ballistic vortices. Suppression of vortices\nby disorder and phonon scattering therefore provides a clear diagnostic of the\nmicroscopic origin of vorticity in electron systems.",
        "positive": "Phonon Transport in Suspended Single Layer Graphene: We report the first temperature dependent phonon transport measurements in\nsuspended Cu-CVD single layer graphene (SLG) from 15K to 380K using\nmicrofabricated suspended devices. The thermal conductance per unit cross\nsection $\\sigma$/A increases with temperature and exhibits a peak near T~280K\n($\\pm$10K) due to the Umklapp process. At low temperatures (T<140K), the\ntemperature dependent thermal conductivity scales as ~T^{1.5}, suggesting that\nthe main contribution to thermal conductance arises from flexural acoustic (ZA)\nphonons in suspended SLG. The $\\sigma$/A reaches a high value of 1.7$\\times10^5\nT^{1.5}$ W/m^2K, which is approaching the expected ballistic phonon thermal\nconductance for two-dimensional graphene sheets. Our results not only clarify\nthe ambiguity in the thermal conductance, but also demonstrate the potential of\nCu-CVD graphene for heat related applications."
    },
    {
        "anchor": "Magneto-transport in a binary alloy ring: Magneto-transport properties are investigated in a binary alloy ring\nsubjected to an Aharonov-Bohm (AB) flux \\phi within a single-band\nnon-interacting tight-binding framework. In the first part, we expose\nanalytically the behavior of persistent current in an isolated ordered binary\nalloy ring as functions of electron concentration N_e and AB flux \\phi. While,\nin the second part of the article, we discuss electron transport properties\nthrough a binary alloy ring attached to two semi-infinite one-dimensional\nmetallic electrodes. The effect of impurities is also analyzed. From our study\nwe propose that under suitable choices of the parameter values the system can\nact as a p-type or an n-type semiconductor.",
        "positive": "Electrical control of valley-Zeeman spin-orbit coupling-induced spin\n  precession at room temperature: The ultimate goal of spintronics is achieving electrically controlled\ncoherent manipulation of the electron spin at room temperature to enable\ndevices such as spin field-effect transistors. With conventional materials,\ncoherent spin precession has been observed in the ballistic regime and at low\ntemperatures only. However, the strong spin anisotropy and the valley character\nof the electronic states in 2D materials provide unique control knobs to\nmanipulate spin precession. Here, by manipulating the anisotropic spin-orbit\ncoupling in bilayer graphene by the proximity effect to WSe$_2$, we achieve\ncoherent spin precession in the absence of an external magnetic field, even in\nthe diffusive regime. Remarkably, the sign of the precessing spin polarization\ncan be tuned by a back gate voltage and by a drift current. Our realization of\na spin field-effect transistor at room temperature is a cornerstone for the\nimplementation of energy-efficient spin-based logic."
    },
    {
        "anchor": "Ultrafast, polarized, single-photon emission from m-plane InGaN Quantum\n  Dots on GaN nanowires: We demonstrate single photon emission from self-assembled m-plane InGaN\nquantum dots (QDs) embedded on the side-walls of GaN nanowires. A combination\nof electron microscopy, cathodoluminescence, time-resolved micro-PL and photon\nautocorrelation experiments give a thorough evaluation of the QDs structural\nand optical properties. The QD exhibits anti-bunched emission up to 100 K, with\na measured autocorrelation function of g^2(0) = 0.28 (0.03) at 5 K. Studies on\na statistically significant number of QDs show that these m-plane QDs exhibit\nvery fast radiative lifetimes (260 +/- 55 ps) suggesting smaller internal\nfields than any of the previously reported c-plane and a-plane QDs. Moreover,\nthe observed single photons are almost completely linearly polarized aligned\nperpendicular to the crystallographic c-axis with a degree of linear\npolarization of 0.84 +/- 0.12. Such InGaN QDs incorporated in a nanowire system\nmeet many of the requirements for implementation into quantum information\nsystems and could potentially open the door to wholly new device concepts.",
        "positive": "Optical activity of quantum wells: We report on the observation of optical activity of quantum wells resulting\nin the conversion of the light polarization state controlled by the light\npropagation direction. The polarization conversion is detected in reflection\nmeasurements. We show that a pure $s$-polarized light incident on a quantum\nwell is reflected as an elliptically polarized wave. The signal is drastically\nenhanced in the vicinity of the light-hole exciton resonance. We show that the\npolarization conversion is caused by the spin-orbit splitting of the light hole\nstates and the birefringence of the studied structure. The bulk inversion\nasymmetry constant $\\beta_{h} \\approx 0.14$ eV\\AA, is determined for the ground\nlight hole subband in a 10 nm ZnSe/ZnMgSSe quantum well."
    },
    {
        "anchor": "Non-Hermitian second-order skin and topological modes: The skin effect and topological edge states in non-Hermitian system have been\nwell-studied, and the second-order skin effect and corner modes have also been\nproposed in non-Hermitian system recently. In this paper, we construct the\nnested tight-binding formalism to research the second-order corner modes\nanalytically, which is a direct description of the generic non-Hermitian\ntight-binding model without other assumptions. Within this formalism, we obtain\nthe exact solutions of second-order topological zero-energy corner modes for\nthe non-Hermitian four-band model. We validate the nested tight-binding\nformalism in the hybrid skin-topological corner modes for the four-band model\nand a non-Hermitian two-dimensional (2D) extrinsic model. In addition, we\nexactly illustrate the corner modes induced by second-order skin effect for a\nsimplest 2D non-Hermitian model by the nested tight-binding formalism.",
        "positive": "Interplay between sublattice and spin symmetry breaking in graphene: We study the effect of sublattice symmetry breaking on the electronic,\nmagnetic and transport properties of two dimensional graphene as well as zigzag\nterminated one and zero dimensional graphene nanostructures. The systems are\ndescribed with the Hubbard model within the collinear mean field approximation.\nWe prove that for the non-interacting bipartite lattice with unequal number of\natoms in each sublattice midgap states still exist in the presence of a\nstaggered on-site potential $\\pm \\Delta/2$. We compute the phase diagram of\nboth 2D and 1D graphene with zigzag edges, at half-filling, defined by the\nnormalized interaction strength $U/t$ and $\\Delta/t$, where $t$ is the first\nneighbor hopping. In the case of 2D we find that the system is always\ninsulating and, we find the $U_c(\\Delta)$ curve above which the system goes\nantiferromagnetic.\n  In 1D we find that the system undergoes a phase transition from non-magnetic\ninsulator for $U<U_C(\\Delta)$ to a phase with ferromagnetic edge order and\nantiferromagnetic inter-edge coupling. The conduction properties of the\nmagnetic phase depend on $\\Delta$ and can be insulating, conducting and even\nhalf-metallic, yet the total magnetic moment in the system is zero. We compute\nthe transport properties of a heterojunction with two non-magnetic graphene\nribbon electrodes connected to a finite length armchair ribbon and we find a\nstrong spin filter effect."
    },
    {
        "anchor": "Quasiparticles for quantum dot array in graphene and the associated\n  Magnetoplasmons: We calculate the low-frequency magnetoplasmon excitation spectrum for a\nsquare array of quantum dots on a two-dimensional (2D) graphene layer. The\nconfining potential is linear in the distance from the center of the quantum\ndot. The electron eigenstates in a magnetic field and confining potential are\nmapped onto a 2D plane of electron-hole pairs in an effective magnetic field\nwithout any confinement. The tight-binding model for the array of quantum dots\nleads to a wavefunction with inter-dot mixing of the quantum numbers associated\nwith an isolated quantum dot. For chosen confinement, magnetic field, wave\nvector and frequency, we plot the dispersion equation as a function of the\nperiod $d$ of the lattice. We obtain those values of $d$ which yield collective\nplasma excitations. For the allowed transitions between the valence and\nconduction bands in our calculations, we obtain plasmons when $d \\lesssim 100\n{\\AA}$.",
        "positive": "Thermodynamics of small Fermi systems: quantum statistical fluctuations: We investigate the probability distribution of the quantum fluctuations of\nthermodynamic functions of finite, ballistic, phase-coherent Fermi gases.\nDepending on the chaotic or integrable nature of the underlying classical\ndynamics, on the thermodynamic function considered, and on temperature, we find\nthat the probability distributions are dominated either (i) by the local\nfluctuations of the single-particle spectrum on the scale of the mean level\nspacing, or (ii) by the long-range modulations of that spectrum produced by the\nshort periodic orbits. In case (i) the probability distributions are computed\nusing the appropriate local universality class, uncorrelated levels for\nintegrable systems and random matrix theory for chaotic ones. In case (ii) all\nthe moments of the distributions can be explicitly computed in terms of\nperiodic orbit theory, and are system-dependent, non-universal, functions. The\ndependence on temperature and number of particles of the fluctuations is\nexplicitly computed in all cases, and the different relevant energy scales are\ndisplayed."
    },
    {
        "anchor": "Nonperturbative nonlinear effects in the dispersion relations for TE and\n  TM plasmons on two-dimensional materials: We analytically obtain the dispersion relations for transverse-electric (TE)\nand transverse-magnetic (TM) surface plasmon-polaritons in a nonlinear\ntwo-dimensional (2D) conducting material lying between two Kerr-type dielectric\nmedia. To this end, we use Maxwell's equations within the quasi-electrostatic,\nweakly dissipative regime. We show that the wavelength and propagation distance\nof surface plasmons decrease due to the nonlinearity of the surrounding\ndielectric. In contrast, the effect of the nonlinearity of the 2D material\ndepends on the signs of the real and imaginary parts of the third-order\nconductivity. Notably, the dispersion relations obtained by naively replacing\nthe permittivity of the dielectric medium by its nonlinear counterpart in the\nrespective dispersion relations of the linear regime are not accurate. We apply\nour analysis to the case of doped graphene and make predictions for the\nTM-polarized surface plasmon wavelength and propagation distance.",
        "positive": "Near-unity indistinguishability single photon source for large-scale\n  integrated quantum optics: Integrated single photon sources are key building blocks for realizing\nscalable devices for quantum information processing. For such applications\nhighly coherent and indistinguishable single photons on a chip are required.\nHere we report on a triggered resonance fluorescence single photon source based\non In(Ga)As/GaAs quantum dots coupled to single- and multi-mode ridge\nwaveguides. We demonstrate the generation of highly linearly polarized\nresonance fluorescence photons with 99.1% (96.0%) single-photon purity and\n97.5% (95.0%) indistinguishability in case of multi-mode (single-mode)\nwaveguide devices fulfilling the strict requirements imposed by\nmulti-interferometric quantum optics applications. Our integrated triggered\nsingle photon source can be readily scaled up, promising a realistic pathway\nfor on-chip linear optical quantum simulation, quantum computation and quantum\nnetworks."
    },
    {
        "anchor": "One-Dimensional van der Waals Quantum Materials -- State of the Art and\n  Perspectives: The advent of graphene and other two-dimensional van der Waals materials,\nwith their unique electrical, optical, and thermal properties, has resulted in\ntremendous progress for fundamental science. Recent developments suggest that\ntaking one more step down in dimensionality - from monolayer, atomic sheets to\nindividual atomic chains - can bring exciting prospects as the ultimate limit\nin material downscaling is reached while establishing an entirely new field of\none-dimensional quantum materials. Here we review this emerging area of\none-dimensional van der Waals quantum materials and anticipate its future\ndirections. We focus on quantum effects associated with the charge-density-wave\ncondensate, strongly-correlated phenomena, topological phases, and other unique\nphysical characteristics, which are attainable specifically in van der Waals\nmaterials of lower dimensionality. Possibilities for engineering the properties\nof quasi-one-dimensional materials via compositional changes, vacancies, and\ndefects, as well as the prospects of their applications in composites are also\ndiscussed.",
        "positive": "Controlling magnetic skyrmion nucleation with Ga+ ion irradiation: In this paper, we show that magnetic skyrmion nucleation can be controlled\nusing Ga+ ion irradiation, which manipulates the magnetic interface effects (in\nparticular the magnetic anisotropy and Dzyaloshinskii-Moriya interaction) that\ngovern the stability and energy cost of skyrmions in thin film systems. We\nsystematically and quantitatively investigated what effect these changes have\non the nucleation of magnetic skyrmions. Our results indicate that the energy\ncost of skyrmion nucleation can be reduced up to 26% in the studied dose range\nand that it scales approximately linearly with the square root of the\ndomain-wall energy density. Moreover, the total number of nucleated skyrmions\nin irradiated devices after nucleation was found to depend linearly on the ion\ndose and could be doubled compared to nonirradiated devices. These results show\nthat ion irradiation cannot only be used to enable local nucleation of\nskyrmions, but that it also allows for fine control of the threshold and\nefficiency of the nucleation process."
    },
    {
        "anchor": "Super-Poissonian shot noise of squeezed-magnon mediated spin transport: The magnetization of a ferromagnet (F) driven out of equilibrium injects pure\nspin current into an adjacent conductor (N). Such F$|$N bilayers have become\nbasic building blocks in a wide variety of spin based devices. We evaluate the\nshot noise of the spin current traversing the F$|$N interface when F is\nsubjected to a coherent microwave drive. We find that the noise spectrum is\nfrequency independent up to the drive frequency, and increases linearly with\nfrequency thereafter. The low frequency noise indicates super-Poissonian spin\ntransfer, which results from quasi-particles with effective spin $\\hbar^* =\n\\hbar (1 + \\delta)$. For typical ferromagnetic thin films, $\\delta \\sim 1$ is\nrelated to the dipolar interaction-mediated squeezing of F eigenmodes.",
        "positive": "Ultimate photo-induced Kerr rotation achieved in semiconductor\n  microcavities: Photoinduced Kerr rotation by more than $\\pi /2$ radians is demonstrated in\nplanar quantum well microcavity in the strong coupling regime. This result is\nclose to the predicted theoretical maximum of $\\pi $. It is achieved by\nengineering microcavity parameters such that the optical impedance matching\ncondition is reached at the smallest negative detuning between exciton\nresonance and the cavity mode. This ensures the optimum combination of the\nexciton induced optical non-linearity and the enhancement of the Kerr angle by\nthe cavity. Comprehensive analysis of the polarization state of the light in\nthis regime shows that both renormalization of the exciton energy and the\nsaturation of the excitonic resonance contribute to the observed optical\nnonlinearities."
    },
    {
        "anchor": "Charge-memory polaron effect in molecular junctions: The charge-memory effect, bistability and switching between charged and\nneutral states of a molecular junction, as observed in recent STM experiments,\nis considered within a minimal polaron model. We show that in the case of\nstrong electron-vibron interaction the rate of spontaneous quantum switching\nbetween charged and neutral states is exponentially suppressed at zero bias\nvoltage but can be tuned through a wide range of finite switching timescales\nupon changing the bias. We further find that, while junctions with symmetric\nvoltage drop give rise to random switching at finite bias, asymmetric junctions\nexhibit hysteretic behavior enabling controlled switching. Lifetimes and\ncharge-voltage curves are calculated by the master equation method for weak\ncoupling to the leads and at stronger coupling by the equation-of-motion method\nfor nonequilibrium Green functions.",
        "positive": "Site-dependent evolution of electrical conductance from tunneling to\n  atomic point contact: Using scanning tunneling microscopy (STM), we investigated the evolution of\nelectrical conductance between a Pb tip and Pb(111) surface from tunneling to\natomic point contact at a site that was defined with atomic precision. We found\nthat the conductance evolution depended on the contact site, for instance,\non-top, bridge, or hollow (hcp and fcc) sites in the Pb lattice. In the\ntransition from tunneling to contact regimes, the conductance measured at the\non-top site was enhanced. In the point contact regime, the hollow sites had\nconductances larger than those of the other sites, and between the hollow\nsites, the hcp site had a conductance larger than that of the fcc site. We also\nobserved the enhancement and reversal of the apparent height in atomically\nresolved high-current STM images, consistent with the results of the\nconductance traces. Our results indicate the importance of atomic configuration\nin the conductance of atomic junctions and suggest that attractive chemical\ninteractions have a significant role in electron transport between contacting\natoms."
    },
    {
        "anchor": "Nonuniversal Critical Conductance Fluctuations of Chiral Surface States\n  in the Bulk Integral Quantum Hall Effect -- An Exact Calculation: The chiral surface electrons in the bulk quantum Hall effect probably form\nthe first extended system in which conductance fluctuations can be calculated\nnon-perturbatively in the presence of disorder. By use of the Kubo formula with\nappropriate boundary conditions, we calculate exactly the variance of\nconductance with non-perturbative methods. We find that the conductance\nfluctuations of this system are ``nonuniversal'' and the variance of the\nconductance scales in a very peculiar way. This result can be checked with\nexact computation using the Landauer-Buttiker formula and both methods show the\nsame scaling behavior. We have also calculated the diffusion constant\nfluctuations exactly. We find that the diffusion constant fluctuations vanish\nand thus play no role in the conductance fluctuations.",
        "positive": "Energy loss of charged particles in a two-dimensional Dirac plasma: The stopping power and energy loss rate of charged particles traversing a\ntwo-dimensional Dirac plasma is investigated. The Dirac plasma considered here\nmodels a solid state system, recently realized graphene monolayer, where the\nconduction electrons obey the Dirac-like equation and exhibit a linear in\nmomentum dispersion relation. Theoretical work presented here is based on the\nthe dielectric response function and the dynamical structure function within\nthe Random-Phase-Approximation (RPA)."
    },
    {
        "anchor": "Progress and prospects in the quantum anomalous Hall effect: The quantum anomalous Hall effect refers to the quantization of Hall effect\nin the absence of applied magnetic field. The quantum anomalous Hall effect is\nof topological nature and well suited for field-free resistance metrology and\nlow-power information processing utilizing dissipationless chiral edge\ntransport. In this Perspective, we provide an overview of the recent\nachievements as well as the materials challenges and opportunities, pertaining\nto engineering intrinsic/interfacial magnetic coupling, that are expected to\npropel future development of the field.",
        "positive": "Submolecular-scale control of phototautomerization: Many natural and artificial reactions including photosynthesis or\nphotopolymerization are initiated by stimulating organic molecules into an\nexcited state, which enables new reaction paths. Controlling light-matter\ninteraction can influence this key concept of photochemistry, however, it\nremained a challenge to apply this strategy to control photochemical reactions\nat the atomic scale. Here, we profit from the extreme confinement of the\nelectromagnetic field at the apex of a scanning tunneling microscope (STM) tip\nto drive and control the rate of a free-base phthalocyanine\nphototautomerization with submolecular precision. By tuning the laser\nexcitation wavelength and choosing the STM tip position, we control the\nphototautomerization rate and the relative tautomer population. This\nsub-molecular optical control can be used to study any other photochemical\nprocesses."
    },
    {
        "anchor": "Anomalous decoherence effect in a quantum bath: Decoherence of quantum objects in noisy environments is important in quantum\nsciences and technologies. It is generally believed that different processes\ncoupled to the same noise source should have similar decoherence behaviors and\nstronger noises would cause faster decoherence. Here we show that in a quantum\nbath, the case can be the opposite. In particular, we predict that the\nmulti-transition of a nitrogen-vacancy center spin-1 in diamond can have longer\ncoherence time than the single-transitions, even though the former suffers\ntwice stronger noises from the nuclear spin bath than the latter. This\nanomalous decoherence effect is due to manipulation of the bath evolution via\nflips of the center spin.",
        "positive": "Spectral flow and global topology of the Hofstadter butterfly: We study the relation between the global topology of the Hofstadter butterfly\nof a multiband insulator and the topological invariants of the underlying\nHamiltonian. The global topology of the butterfly, i.e., the displacement of\nthe energy gaps as the magnetic field is varied by one flux quantum, is\ndetermined by the spectral flow of energy eigenstates crossing gaps as the\nfield is tuned. We find that for each gap this spectral flow is equal to the\ntopological invariant of the gap, i.e., the net number of edge modes traversing\nthe gap. For periodically driven systems, our results apply to the spectrum of\nquasienergies. In this case, the spectral flow of the sum of all the\nquasienergies gives directly the Rudner invariant."
    },
    {
        "anchor": "Chiral spin textures creation and dynamics in a rectangular\n  nanostructure: Controlled creation of stable chiral spin textures is required to use them as\nan energy-efficient information carrier in spintronics. Here we have studied\nthe stable creation of isolated chiral spin texture (skyrmion and antiskyrmion)\nand its pair through the magnetization reversal of a rectangular nanostructure\nusing spin-polarized currents. An isolated spin texture is created through a\nnegative current pulse. Dynamics of the stable spin texture are explored under\nexternal magnetic fields, and the resonant frequencies are calculated. A stable\nskyrmion pair is created using an asymmetric current pulse, and their\ninteraction is studied using the Thiele equation. The stability of isolated or\npaired spin texture depends on the DMI strength, spin-polarized current\ndensity, and pulse duration. In addition, the stability of the skyrmion pair\ndepends on their initial separation, and a threshold for the separation between\nskyrmions of 78 nm is observed.",
        "positive": "Multistage Kondo effect in a multiterminal geometry: A modular quantum\n  interferometer: Quantum systems characterized by an interplay between several resonance\nscattering channels demonstrate very rich physics. To illustrate it we consider\na multistage Kondo effect in nanodevices as a paradigmatic model for a\nmultimode resonance scattering. We show that the channel crosstalk results in a\ndestructive interference between the modes. This interplay can be controlled by\nmanipulating the tunneling junctions in the multilevel and multiterminal\ngeometry. We present a full-fledged theory of the multistage Kondo effect at\nthe strong-coupling Fermi-liquid fixed point and discuss the influence of\nquantum interference effects to the quantum transport observables."
    },
    {
        "anchor": "Pecularities of Hall effect in\n  GaAs/\u03b4<Mn>/GaAs/In\\timesGa1-\\timesAs/GaAs (\\times {\\approx} 0.2)\n  heterostructures with high Mn content: Transport properties of GaAs/{\\delta}<Mn>/GaAs/In\\timesGa1-\\timesAs/GaAs\nstructures containing InxGa1-xAs (\\times {\\approx} 0.2) quantum well (QW) and\nMn delta layer (DL) with relatively high, about one Mn monolayer (ML) content,\nare studied. In these structures DL is separated from QW by GaAs spacer with\nthe thickness ds = 2-5 nm. All structures possess a dielectric character of\nconductivity and demonstrate a maximum in the resistance temperature dependence\nRxx(T) at the temperature {\\approx} 46K which is usually associated with the\nCurie temperature Tc of ferromagnetic (FM) transition in DL. However, it is\nfound that the Hall effect concentration of holes pH in QW does not decrease\nbelow TC as one ordinary expects in similar systems. On the contrary, the\ndependence pH(T) experiences a minimum at T = 80-100 K depending on the spacer\nthickness, then increases at low temperatures more strongly than ds is smaller\nand reaches a giant value pH = (1-2)\\cdot10^13 cm^(-2). Obtained results are\ninterpreted in the terms of magnetic proximity effect of DL on QW, leading to\ninduce spin polarization of the holes in QW. Strong structural and magnetic\ndisorder in DL and QW, leading to the phase segregation in them is taken into\nconsideration. The high pH value is explained as a result of compensation of\nthe positive sign normal Hall effect component by the negative sign anomalous\nHall effect component.",
        "positive": "Photonic density of states enhancement in finite graphene multilayers: We consider the optical properties of finite systems composed of a series of\ngraphene sheets separated by thin dielectric layers. Because these systems\nrespond as conductors to electric fields in the plane of the graphene sheets\nand as insulators to perpendicular electric fields, they can be expected to\nhave properties similar to those of hyperbolic metamaterials. We show that\nunder typical experimental conditions graphene/dielectric multilayers have\nenhanced Purcell factors, and enhanced photonic densities-of-states in both the\nTHz and mid-IR frequency range. These behaviors can be traced to the coupled\nplasmon modes of the multi-layer graphene system. We show that these results\ncan be obtained with just a few layers of graphene."
    },
    {
        "anchor": "Optical Conductivity of Weyl Semimetals and Signatures of the Gapped\n  Semimetal Phase Transition: The interband optical response of a three-dimensional Dirac cone is linear in\nphoton energy ($\\Omega$). Here, we study the evolution of the interband\nresponse within a model Hamiltonian which contains Dirac, Weyl and gapped\nsemimetal phases. In the pure Dirac case, a single linear dependence is\nobserved, while in the Weyl phase, we find two quasilinear regions with\ndifferent slopes. These regions are also distinct from the large-$\\Omega$\ndependence. As the boundary between the Weyl (WSM) and gapped phases is\napproached, the slope of the low-$\\Omega$ response increases, while the\nphoton-energy range over which it applies decreases. At the phase boundary, a\nsquare root behaviour is obtained which is followed by a gapped response in the\ngapped semimetal phase. The density of states parallels these behaviours with\nthe linear law replaced by quadratic behaviour in the WSM phase and the square\nroot dependence at the phase boundary changed to $|\\omega|^{3/2}$. The optical\nspectral weight under the intraband (Drude) response at low temperature ($T$)\nand/or small chemical potential ($\\mu$) is found to change from $T^2$ ($\\mu^2$)\nin the WSM phase to $T^{3/2}$ ($|\\mu|^{3/2}$) at the phase boundary.",
        "positive": "Observation of reduced 1/f noise in Graphene field effect transistors on\n  Boron Nitride substrates: We have investigated the low frequency (f) flicker (also called 1/f) noise of\nsingle-layer graphene devices on h-BN (placed on SiO2/Si) along with those on\nSiO2/Si. We observe that the devices fabricated on h-BN have on average one\norder of magnitude lower noise amplitude compared with devices fabricated on\nSiO2/Si. We associate this noise reduction to the lower densities of impurities\nand trap sites in h-BN than in SiO2. Furthermore, the gate voltage dependent\nnoise amplitude shows a broad maximum at Dirac point for devices on h-BN, in\ncontrast to the M-shaped behavior showing a minimum at Dirac point for devices\non SiO2, consistent with the reduced charge inhomogeneity (puddles) for\ngraphene on h-BN. This study demonstrates that the use of h-BN as a substrate\nor dielectric can be a simple and efficient noise reduction technique valuable\nfor electronic applications of graphene and other nanomaterials."
    },
    {
        "anchor": "Ultrafast Switching in Synthetic Antiferromagnet with Bilayer Rare-Earth\n  Transition-Metal Ferrimagnets: In spintronics, it is important to be able to manipulate magnetization\nrapidly and reliably. Several methods can control magnetization, such as by\napplying current pulses or magnetic fields. An applied current can reverse\nmagnetization with nanosecond speed through the spin torque effect. For faster\nswitching, subpicosecond switching with femtoseconds laser pulse has been\nachieved in amorphous rare-earth transition-metal ferrimagnets. In this study,\nwe employed atomistic simulations to investigate ultrafast switching in a\nsynthetic antiferromagnet with bilayer amorphous FeGd ferrimagnets. Using a\ntwo-temperature model, we demonstrated ultrafast switching in this synthetic\nantiferromagnet without external magnetic fields. Furthermore, we showed that\nif we initially stabilize a skyrmion in this heterostructure, the ultrafast\nlaser can switch the skyrmion state using the same mechanism. Furthermore, this\nbilayer design allows the control of each ferrimagnetic layer individually and\nopens the possibility for a magnetic tunnel junction.",
        "positive": "Enhanced photoluminescence emission from two-dimensional silicon\n  photonic crystal nanocavities: We present a temperature dependent photoluminescence study of silicon optical\nnanocavities formed by introducing point defects into two-dimensional photonic\ncrystals. In addition to the prominent TO phonon assisted transition from\ncrystalline silicon at ~1.10 eV we observe a broad defect band luminescence\nfrom ~1.05-1.09 eV. Spatially resolved spectroscopy demonstrates that this\ndefect band is present only in the region where air-holes have been etched\nduring the fabrication process. Detectable emission from the cavity mode\npersists up to room-temperature, in strong contrast the background emission\nvanishes for T > 150 K. An Ahrrenius type analysis of the temperature\ndependence of the luminescence signal recorded either in-resonance with the\ncavity mode, or weakly detuned, suggests that the higher temperature stability\nmay arise from an enhanced internal quantum efficiency due to the\nPurcell-effect."
    },
    {
        "anchor": "Anomalous robustness of the 5/2 fractional quantum Hall state near a\n  sharp phase boundary: We report magneto-transport measurements in wide GaAs quantum wells with\ntunable density to probe the stability of the fractional quantum Hall effect at\nfilling factor $\\nu = $ 5/2 in the vicinity of the crossing between Landau\nlevels (LLs) belonging to the different (symmetric and antisymmetric) electric\nsubbands. When the Fermi energy ($E_F$) lies in the excited-state LL of the\nsymmetric subband, the 5/2 quantum Hall state is surprisingly stable and gets\neven stronger near this crossing, and then suddenly disappears and turns into a\nmetallic state once $E_F$ moves to the ground-state LL of the antisymmetric\nsubband. The sharpness of this disappearance suggests a first-order transition.",
        "positive": "Interface Trap Density Metrology of state-of-the-art undoped Si\n  n-FinFETs: The presence of interface states at the MOS interface is a well-known cause\nof device degradation. This is particularly true for ultra-scaled FinFET\ngeometries where the presence of a few traps can strongly influence device\nbehavior. Typical methods for interface trap density (Dit) measurements are not\nperformed on ultimate devices, but on custom designed structures. We present\nthe first set of methods that allow direct estimation of Dit in\nstate-of-the-art FinFETs, addressing a critical industry need."
    },
    {
        "anchor": "Transport in Carbon Nanotubes: 2LSU(2) regime reveals subtle competition\n  between Kondo and Intermediate Valence states: In this work, we use three different numerical techniques to study the charge\ntransport properties of a system in the two-level SU(2) (2LSU2) regime,\nobtained from an SU(4) model Hamiltonian by introducing orbital mixing of the\ndegenerate orbitals via coupling to the leads. SU(4) Kondo physics has been\nexperimentally observed, and studied in detail, in Carbon Nanotube Quantum\nDots. Adopting a two molecular orbital basis, the Hamiltonian is recast into a\nform where one of the molecular orbitals decouples from the charge reservoir,\nalthough still interacting capacitively with the other molecular orbital. This\nbasis transformation explains in a clear way how the charge transport in this\nsystem turns from double- to single-channel when it transitions from the SU(4)\nto the 2LSU2 regime. The charge occupancy of these molecular orbitals displays\ngate-potential-dependent occupancy oscillations that arise from a competition\nbetween the Kondo and Intermediate Valence states. The determination of whether\nthe Kondo or the Intermediate Valence state is more favorable, for a specific\nvalue of gate potential, is assessed by the definition of an energy scale\n$T_0$, which is calculated through DMRG. We speculate that the calculation of\n$T_0$ may provide experimentalists with a useful tool to analyze correlated\ncharge transport in many other systems. For that, a current work is underway to\nimprove the numerical accuracy of its DRMG calculation and explore different\ndefinitions.",
        "positive": "Electron localization in periodically strained graphene: Pseudo-magnetic field (PMF) in deformed graphene has been proposed as a\npromising and flexible method to quantum-confine electronic states and create\ngaps in the local density of states. Motivated by this perspective, we\nnumerically analyze various different configurations leading to electronic\nlocalization and band flattening in periodically strained graphene. In\nparticular, we highlight the existence of a fine structure in the pseudo-Landau\nlevels confined in large-PMF regions, the emergence of states confined to PMF\nnodes as well as of snake-like orbits. In our paper, we further analyze the\nimportance of the relative rotation and asymmetry of the strain lattice with\nrespect to the atomic lattice and show how it can be used to modulate the PMF\nperiodicity and to create localized orbits far from the strain points. Possible\nimplementations and applications of the simulated structures are discussed."
    },
    {
        "anchor": "Interplay of Rayleigh and Peierls Instabilities in Metallic Nanowires: A quantum-mechanical stability analysis of metallic nanowires within the\nfree-electron model is presented. The stability is determined by an interplay\nof electron-shell effects, the Rayleigh instability due to surface tension, and\nthe Peierls instability. Although the latter effect limits the maximum length\nalso for wires with \"magic radii\", it is found that nanowires in the micrometer\nrange can be stable at room temperature.",
        "positive": "Bundling dynamics regulates the active mechanics and transport in carbon\n  nanotube networks: High-density carbon nanotube networks (CNNs) continue to attract interest as\nactive elements in nanoelectronic devices, nanoelectromechanical systems (NEMS)\nand multifunctional nanocomposites. The interplay between the network\nnanostructure and the its properties is crucial, yet current understanding\nremains limited to the passive response. Here, we employ a novel superstructure\nconsisting of millimeter-long vertically aligned singe walled carbon nanotubes\n(SWCNTs) sandwiched between polydimethylsiloxane (PDMS) layers to quantify the\neffect of two classes of mechanical stimuli, film densification and stretching,\non the electronic and thermal transport across the network. The network deforms\neasily with increase in electrical and thermal conductivities suggestive of\nfloppy yet highly reconfigurable network. Insight from atomistically informed\ncoarse-grained simulations uncover an interplay between the extent of lateral\nassembly of the bundles, modulated by surface zipping/unzipping, and the\nelastic energy associated with the bent conformations of the nanotubes/bundles.\nDuring densification, the network becomes highly interconnected yet we observe\na modest increase in bundling primarily due to the reduced spacing between the\nSWCNTs. The stretching, on the other hand, is characterized by an initial\ndebundling regime as the strain accommodation occurs via unzipping of the\nbranched interconnects, followed by rapid re-bundling as the strain transfers\nto the increasingly aligned bundles. In both cases, the increase in the\nelectrical and thermal conductivity is primarily due to the increase in bundle\nsize; the changes in network connectivity have a minor effect on the transport.\nOur results have broad implications for filamentous networks of inorganic\nnanoassemblies composed of interacting tubes, wires and ribbons/belts."
    },
    {
        "anchor": "Unraveling the dynamics of magnetization in topological\n  insulator-ferromagnet heterostructures via spin-orbit torque: Spin-orbit coupling stands as a pivotal determinant in the realm of condensed\nmatter physics. In recent, its profound influence on spin dynamics opens up a\ncaptivating arena with promising applications. Notably, the topological\ninsulator-ferromagnet heterostructure has been recognized for inducing spin\ndynamics through applied current, driven by spin-orbit torque. Building upon\nrecent observations revealing spin flip signals within this heterostructure,\nour study elucidates the conditions governing spin flips by studying the\nmagnetization dynamics. We establish that the interplay between spin-anisotropy\nand spin-orbit torque plays a crucial role in shaping the physics of\nmagnetization dynamics within the heterostructure. Furthermore, we categorize\nvarious modes of magnetization dynamics, constructing a comprehensive phase\ndiagram across distinct energy scales, damping constants, and applied\nfrequencies. This research not only offers insights into controlling spin\ndirection but also charts a new pathway to the practical application of\nspin-orbit coupled systems.",
        "positive": "Helical Dirac-Majorana interferometer in a superconductor-topological\n  insulator sandwich structure: In the heterostructure composed of a topological insulator sandwiched by two\ns-wave superconductors, the time reversal invariant topological superconducting\nphase, possessing helical Majorana edge modes, is found to exist when the two\ns-wave superconductors form a Josephson junction with a pi phase shift. Based\non such a heterostructure, a helical Dirac-Majorana interferometer is proposed\nto directly measure a unique transport signature of the helical Majorana modes.\nFurthermore, we envision how our proposal can be realized on the basis of\nexisting materials such as Bi2Se3 or Bi2Te3 thin films."
    },
    {
        "anchor": "Spin filtering in a hybrid ferromagnetic-semiconductor microstructure: We fabricated a hybrid structure in which cobalt and permalloy micromagnets\nproduce a local in-plane spin-dependent potential barrier for high-mobility\nelectrons at the GaAs/AlGaAs interface. Spin effects are observed in ballistic\ntransport in the tens' millitesla range of the external field, and are\nattributed to switching between Zeeman and Stern-Gerlach modes -- the former\ndominating at low electron densities.",
        "positive": "Single-photon nonlinear optics with Kerr-type nanostructured materials: We employ a quantum theory of the nonlinear optical response from an actual\nsolid-state material possessing an intrinsic bulk contribution to the\nthird-order nonlinear susceptibility (Kerr-type nonlinearity), which can be\narbitrarily nanostructured to achieve diffraction-limited electromagnetic field\nconfinement. By calculating the zero-time delay second-order correlation of the\ncavity field, we set the conditions for using semiconductor or insulating\nmaterials with near-infrared energy gaps as efficient means to obtain\nsingle-photon nonlinear behavior in prospective solid-state integrated devices,\nalternative to ideal sources of quantum radiation such as, e.g., single\ntwo-level emitters."
    },
    {
        "anchor": "Confinement-enhanced spin relaxation for electron ensembles in large\n  quantum dots: We present a numerical study of spin relaxation in a semiclassical electron\nensemble in a large ballistic quantum dot. The dot is defined in a GaAs/AlGaAs\nheterojunction system with a two-dimensional electron gas, and relaxation\noccurs due to Dresselhaus and Rashba spin orbit interaction. We find that\nconfinement in a micronscale dot can result in strongly enhanced relaxation\nwith respect to a free two-dimensional electron ensemble, contrary to the\nestablished result that strong confinement or frequent momentum scattering\nreduces relaxation. This effect occurs when the size of the system is on the\norder of the spin precession length, but smaller than the mean free path.",
        "positive": "Electronic Structure and Carrier Mobilities of Twisted Graphene Helix: We have investigated the effect of twisting on electronic band structure,\neffective mass and carrier mobilities of three prototypes of AGNRs (N=6, 7 & 8)\nusing Density functional theory combined with Deformation potential theory and\nEffective mass approximation. It is shown that the influence of twisted modes\nelectron-phonon interaction is smaller than stretching modes, nonetheless,\ntwisting has a profound effect on effective mass and mobilities. Similar to\nearlier reported conclusion in which the ideal N=3n wide HAGNR potentially\nexhibit an electron mobility comparable to intrinsic graphene, we also found\nthat the ideal N=3n+2 HAGNRs hole mobility reside more closely to intrinsic\ngraphene which could be increased further through Fluorine passivation. Thus,\nthe control of the ribbon width along with passivation and extent of\ndeformation are of paramount importance for determining the n-type or p-type of\nribbons. Also, because of strong response to torsional strain, the N=8 F\npassivated AGNRs are the most appropriate for mechanical and high frequency\nswitching. Our results suggest that twisting a ribbon can be considered as a\ngood alternative way for controlled manipulation of the band structure and\ncarrier mobilities for applications in mechanical switching devices."
    },
    {
        "anchor": "Coupled Maxwell and Time-Dependent Orbital Free Density Functional\n  Calculations: Coupled Maxwell and time-dependent orbital-free calculations are implemented\nand tested to describe the interaction of electromagnetic waves and matter. The\ncurrents and induced fields predicted by the orbital-free calculations are\ncompared to time-dependent density functional calculations and very good\nagreement is found for various systems including jellium sheets, jellium\nspheres, atomistic sheets, and icosahedron clusters.",
        "positive": "Cooper-pair propagation and superconducting correlations in graphene: We investigate the Cooper-pair propagation and the proximity effect in\ngraphene under conditions in which the distance L between superconducting\nelectrodes is much larger than the width W of the contacts. In the case of\nundoped graphene, supercurrents may exist with a spatial decay proportional to\nW^2/L^3. This changes upon doping into a 1/L^2 behavior, opening the\npossibility to observe a supercurrent over length scales above 1 micron at\nsuitable doping levels. We also show that there is in general a crossover\ntemperature T ~ v_F/k_B L that marks the onset of the strong decay of the\nsupercurrent, and that corresponds to the scale below which the Cooper pairs\nare not disrupted by thermal effects during their propagation."
    },
    {
        "anchor": "Correlated Counting of Single Electrons in a Nanowire Double Quantum Dot: We report on correlated real-time detection of individual electrons in an\nInAs nanowire double quantum dot. Two self-aligned quantum point contacts in an\nunderlying two-dimensional electron gas material serve as highly sensitive\ncharge detectors for the double quantum dot. Tunnel processes of individual\nelectrons and all tunnel rates are determined by simultaneous measurements of\nthe correlated signals of the quantum point contacts.",
        "positive": "Bilayer Quantum Hall Systems: Spin-Pseudospin Symmetry Breaking and\n  Quantum Phase Transitions: We discuss and review recent advances in our understaning of quantum Hall\nsystems where additional quantum numbers associated with spin and/or layer\n(pseudospin) indices play crucial roles in creating exotic quantum phases.\nAmong the novel quantum phases we discuss are the recently discovered canted\nantiferromagnetic phase, the spontaneous interlayer coherent phase, and various\nspin Bose glass phases. We describe the theoretical models used in studying\nthese novel phases and the various experimental techniques being used to search\nfor these phases. Both zero temperature quantum phase transitions and finite\ntemperature phase transitions are discussed. Emphasis in this article is on the\nrecent developments in novel quantum phases and quantum phase transitions in\nbilayer quantum Hall systems where nontrivial magnetic ground states associated\nwith spontaneous spin symmetry breaking play central role."
    },
    {
        "anchor": "Anomalous Hall Effect in Weyl Metals: We present a theory of the anomalous Hall effect (AHE) in a doped Weyl\nsemimetal, or Weyl metal, including both intrinsic and extrinsic (impurity\nscattering) contributions. We demonstrate that a Weyl metal is distinguished\nfrom an ordinary ferromagnetic metal by the absence of the extrinsic and the\nFermi surface part of the intrinsic contributions to the AHE, as long as the\nFermi energy is sufficiently close to the Weyl nodes. The AHE in a Weyl metal\nis thus shown to be a purely intrinsic, universal property, fully determined by\nthe location of the Weyl nodes in the first Brillouin zone.",
        "positive": "Mesoscopic Tunneling Magnetoresistance: We study spin-dependent transport through\nferromagnet/normal-metal/ferromagnet double tunnel junctions in the mesoscopic\nCoulomb blockade regime. A general transport equation allows us to calculate\nthe conductance in the absence or presence of spin-orbit interaction and for\narbitrary orientation of the lead magnetizations. The tunneling\nmagnetoresistance (TMR), defined at the Coulomb blockade conductance peaks, is\ncalculated and its probability distribution presented. We show that mesoscopic\nfluctuations can lead to the optimal value of the TMR."
    },
    {
        "anchor": "Quartic scaling of sound attenuation with frequency in vitreous silica: Several theoretical approaches to disordered media predict that acoustic\nwaves should undergo a quartic increase in their attenuation coefficient with\nincreasing frequency in the sub-terahertz region. Such Rayleigh-type scattering\nwould be related to the anomalous low-temperature plateau in the thermal\nconductivity and to the so-called boson peak, i.e. an excess of vibrational\nmodes above the Debye density of states at around 1 THz. Brillouin scattering\nof light allows the measurement of sound absorption and velocity dispersion up\nto about 0.1 THz while inelastic x-ray scattering is limited to frequencies\nlarger than about 1 THz. We take advantage of the advent of ultrafast optical\ntechniques to explore the acoustical properties of amorphous SiO2 layers in the\ndifficult but crucial frequency region within this gap. A quartic scaling law\nwith frequency is clearly revealed between 0.2 and 0.9 THz, which is further\nshown to be independent of temperature. This strongly damped regime is\naccompanied by a decrease in the sound velocity already starting from about 0.5\nTHz, in line with theories. Our study assists to clarify the anomalous\nacoustical properties in glasses at frequencies entering the boson peak region.",
        "positive": "Spectroscopy of composite solid-state spin environments for improved\n  metrology with spin ensembles: For precision coherent measurements with ensembles of quantum spins the\nrelevant Figure-of-Merit (FOM) is the product of polarized spin density and\ncoherence lifetime, which is generally limited by the dynamics of the spin\nenvironment. Here, we apply a coherent spectroscopic technique to characterize\nthe dynamics of the composite solid-state spin environment of Nitrogen-Vacancy\n(NV) centers in room temperature diamond. For samples of very different NV\ndensities and impurity spin concentrations, we show that NV FOM values can be\nalmost an order of magnitude larger than previously achieved in other\nroom-temperature solid-state spin systems, and within an order of magnitude of\nthe state-of-the-art atomic system. We also identify a new mechanism for\nsuppression of electronic spin bath dynamics in the presence of a nuclear spin\nbath of sufficient concentration. This suppression could inform efforts to\nfurther increase the FOM for solid-state spin ensemble metrology and collective\nquantum information processing."
    },
    {
        "anchor": "Harmonically trapped fermion gases: exact and asymptotic results in\n  arbitrary dimensions: We investigate the particle and kinetic energy densities of harmonically\ntrapped fermion gases at zero temperature in arbitrary dimensions. We derive\nanalytically a differential equation connecting these densities, which so far\nhave been proven only in one or two dimensions, and give other interesting\nrelations involving several densities or the particle density alone. We show\nthat in the asymptotic limit of large particle numbers, the densities go over\ninto the semi-classical Thomas-Fermi (TF) densities. Hereby the Fermi energy to\nbe used in the TF densities is identified uniquely. We derive an analytical\nexpansion for the remaining oscillating parts and obtain very simple closed\nforms for the leading-order oscillating densities. Finally, we show that the\nsimple TF functional relation $\\tau_{TF}[\\rho]$ between kinetic and particle\ndensity is fulfilled also for the asymptotic quantum densities $\\tau(r)$ and\n$\\rho(r)$ including their leading-order oscillating terms.",
        "positive": "Nanoparticles with Cubic Symmetry: Classification of Polyhedral Shapes: The shape of crystalline nanoparticles (NP) can often be described by\npolyhedra with flat facet surfaces. Thus, structural studies of polyhedral\nbodies can help to describe geometric details of NPs. Here we consider compact\npolyhedra of cubic point symmetry Oh.as simple models. Their surfaces are\ndescribed by facets with normal vectors along selected directions (a, b, c)\ntogether with their symmetry equivalents forming a direction family {abc}. For\ngiven {abc} this yields generic polyhedra with up to 48 facets where we focus\non polyhedra with facets of {abc} = {100}, {110}, and {111}, suggested for\nmetal NPs with cubic lattices. The resulting generic polyhedra, cubic,\nrhombohedral, and octahedral, can serve for the description of non-generic\npolyhedra as intersections of corresponding generic species. Their structural\nproperties are shown to be fully determined by only three structure parameters,\nfacet distances R100, R110, and R111 of three types of facets. This provides a\nphase diagram to completely classify the corresponding Oh symmetry polyhedra.\nStructural properties of all polyhedra, such as shape, size, and facet\ngeometries, are discussed in analytical and numerical detail with visualization\nof characteristic examples. The results may be used for respective nanoparticle\nsimulations but also as a repository assisting the interpretation of structures\nof real compact nanoparticles observed by experiment."
    },
    {
        "anchor": "Physical Consequences of Complex Dimensions of Fractals: It has recently been realized that fractals may be characterized by complex\ndimensions, arising from complex poles of the corresponding zeta function, and\nwe show here that these lead to oscillatory behavior in various physical\nquantities. We identify the physical origin of these complex poles as the\nexponentially large degeneracy of the iterated eigenvalues of the Laplacian,\nand discuss applications in quantum mesoscopic systems such as oscillations in\nthe fluctuation $\\Sigma^2 (E)$ of the number of levels, as a correction to\nresults obtained in Random Matrix Theory. We present explicit expressions for\nthese oscillations for families of diamond fractals, also studied as\nhierarchical lattices.",
        "positive": "Microwave magnetoplasmon absorption by a 2DEG stripe: Microwave absorption by a high mobility 2DEG has been investigated\nexperimentally using sensitive Electron Paramagnetic Resonance cavity\ntechnique. It is found that MW absorption spectra are chiefly governed by\nconfined magnetoplasmon excitations in a 2DEG stripe. Spectra of the 2D\nmagnetoplasmons are studied as a function of magnetic field, MW frequency and\ncarrier density. The electron concentration is tuned by illumination and\nmonitored using optical photoluminescence technique."
    },
    {
        "anchor": "Statistical Majorana Bound State Spectroscopy: Tunnel spectroscopy data for the detection of Majorana bound states (MBS) is\noften criticized for its proneness to misinterpretation of genuine MBS with\nlow-lying Andreev bound states. Here, we suggest a protocol removing this\nambiguity by extending single shot measurements to sequences performed at\nvarying system parameters. We demonstrate how such sampling, which we argue\nrequires only moderate effort for current experimental platforms, resolves the\nstatistics of Andreev side lobes, thus providing compelling evidence for the\npresence or absence of a Majorana center peak.",
        "positive": "Nuclear magnetic resonance spectroscopy of nonequilibrium steady states\n  in quantum dots: The optically induced polarization of localized electron spins in an ensemble\nof quantum dots (QDs) dephases due to the interaction with the surrounding\nnuclear spins. Despite this dephasing, the spins in the QDs can be controlled\nto respond coherently by applying periodic laser pulses, leading to a revival\nof the spin polarization before each pulse. This effect, known as spin mode\nlocking, strongly depends on an emerging selection of certain polarizations of\nthe nuclear spin bath which is driven to a steady state far from equilibrium.\nWe investigate the influence of the nuclear composition in In$_x$Ga$_{1-x}$As\nQDs on this nonequilibrium behavior and demonstrate that nuclear magnetic\nresonances (NMR) appear as very sharp minima in the magnetic field dependence\nof the revival amplitude. This suggests a novel kind of NMR spectroscopy."
    },
    {
        "anchor": "Rigorous numerical study of strong microwave photon-magnon coupling in\n  all-dielectric magnetic multilayers: We demonstrate theoretically a strong local enhancement of the intensity of\nthe in-plane microwave magnetic field in multilayered structures made from a\nmagneto-insulating yttrium iron garnet (YIG) layer sandwiched between two\nnon-magnetic layers with a high dielectric constant matching that of YIG. The\nenhancement is predicted for the excitation regime when the microwave magnetic\nfield is induced inside the multilayer by the transducer of a stripline\nBroadband Ferromagnetic Resonance (BFMR) setup. By means of a rigorous\nnumerical solution of the Landau-Lifshitz-Gilbert equation consistently with\nthe Maxwell's equations, we investigate the magnetisation dynamics in the\nmultilayer. We reveal a strong photon-magnon coupling, which manifests itself\nas anti-crossing of the ferromagnetic resonance (FMR) magnon mode supported by\nthe YIG layer and the electromagnetic resonance mode supported by the whole\nmultilayered structure. The frequency of the magnon mode depends on the\nexternal static magnetic field, which in our case is applied tangentially to\nthe multilayer in the direction perpendicular to the microwave magnetic field\ninduced by the stripline of the BFMR setup. The frequency of the\nelectromagnetic mode is independent of the static magnetic field. Consequently,\nthe predicted photon-magnon coupling is sensitive to the applied magnetic field\nand thus can be used in magnetically tuneable metamaterials based on\nsimultaneously negative permittivity and permeability achievable thanks to the\nYIG layer. We also suggest that the predicted photon-magnon coupling may find\napplications in microwave quantum information systems.",
        "positive": "Quantum point contacts as heat engines: The efficiency of macroscopic heat engines is restricted by the second law of\nthermodynamics. They can reach at most the efficiency of a Carnot engine. In\ncontrast, heat currents in mesoscopic heat engines show fluctuations. Thus,\nthere is a small probability that a mesoscopic heat engine exceeds Carnot's\nmaximum value during a short measurement time. We illustrate this effect using\na quantum point contact as a heat engine. When a temperature difference is\napplied to a quantum point contact, the system may be utilized as a source of\nelectrical power under steady state conditions. We first discuss the optimal\nworking point of such a heat engine that maximizes the generated electrical\npower and subsequently calculate the statistics for deviations of the\nefficiency from its most likely value. We find that deviations surpassing the\nCarnot limit are possible, but unlikely."
    },
    {
        "anchor": "Long-range ferromagnetism of Mn12 acetate single-molecule magnets under\n  a transverse magnetic field: We use neutron diffraction to probe the magnetization components of a crystal\nof Mn12 single-molecule magnets. Each of these molecules behaves, at low\ntemperatures, as a nanomagnet with spin S = 10 and strong anisotropy along the\ncrystallographic c axis. Application of a magnetic field perpendicular to c\ninduces quantum tunneling between opposite spin orientations, enabling the\nspins to attain thermal equilibrium. Below approximately 0.9 K, intermolecular\ninteractions turn this equilibrium state into a ferromagnetically ordered\nphase. However, long range ferromagnetic correlations nearly disappear for\nfields larger 5.5 T, possibly suggesting the existence of a quantum critical\npoint.",
        "positive": "Phase locking in voltage-controlled parametric oscillator: A recent experimental demonstration of a parametric magnetization oscillation\nexcited by applying a microwave voltage to a ferromagnetic metal will be\napplicable not only to a new magnetization switching method but also to\nbio-inspired computing. It should be, however, noted that a phase of the\nparametric magnetization oscillation is not uniquely locked, related to the\nfact that a frequency of the microwave voltage is twice the value of the\nmagnetization oscillation. There are two possible phases in the parametric\noscillation state, and which of the two is realized depends on the initial\ncondition of the magnetization. Here, we examine two approaches to lock the\nphase uniquely. One is to suppress the distribution of the initial state by\nenhancing the perpendicular magnetic anisotropy before applying microwave\nvoltage, and the other is to use a sweeping frequency. Through numerical\nsimulation of the Landau-Lifshitz-Gilbert equation and quantification of locked\nrate, we find that the sweeping frequency is more effective to lock the phase\nof the parametric magnetization oscillation."
    },
    {
        "anchor": "Plasmon-Exciton-Polariton Lasing: Metallic nanostructures provide a toolkit for the generation of coherent\nlight below the diffraction limit. Plasmonic based lasing relies on the\npopulation inversion of emitters (such as organic fluorophores) along with\nfeedback provided by plasmonic resonances. In this regime, known as weak light\nmatter coupling, the radiative characteristics of the system can be described\nby the Purcell effect. Strong light matter coupling between the molecular\nexcitons and electromagnetic field generated by the plasmonic structures leads\nto the formation of hybrid quasi-particles known as plasmon exciton polaritons\n(PEPs). Due to the bosonic character of these quasi particles, exciton\npolariton condensation can lead to laser-like emission at much lower threshold\npowers than in conventional photon lasers. Here, we observe PEP lasing through\na dark plasmonic mode in an array of metallic nanoparticles with a low\nthreshold in an optically pumped organic system. Interestingly, the threshold\npower of the lasing is reduced by increasing the degree of light matter\ncoupling in spite of the degradation of the quantum efficiency of the active\nmaterial, highlighting the ultrafast dynamic responsible for the lasing, i.e.,\nstimulated scattering. These results demonstrate a unique roomtemperature\nplatform for exploring the physics of exciton polaritons in an open cavity\narchitecture and pave the road toward the integration of this on-chip lasing\ndevice with the current photonics and active metamaterial planar technologies.",
        "positive": "Effect of FET geometry on charge ordering of transition metal oxides: We examine the effect of an FET geometry on the charge ordering phase diagram\nof transition metal oxides using numerical simulations of a semiclassical model\nincluding long-range Coulomb fields, resulting in nanoscale pattern formation.\nWe find that the phase diagram is unchanged for insulating layers thicker than\napproximately twice the magnetic correlation length. For very thin insulating\nlayers, the onset of a charge clump phase is shifted to lower values of the\nstrength of the magnetic dipolar interaction, and intermediate diagonal stripe\nand geometric phases can be suppressed. Our results indicate that, for\nsufficiently thick insulating layers, charge injection in an FET geometry can\nbe used to experimentally probe the intrinsic charge ordering phases in these\nmaterials."
    },
    {
        "anchor": "Electron-photon coupling in Mesoscopic Quantum Electrodynamics: Understanding the interaction between cavity photons and electronic\nnanocircuits is crucial for the development of Mesoscopic Quantum\nElectrodynamics (QED). One has to combine ingredients from atomic Cavity QED,\nlike orbital degrees of freedom, with tunneling physics and strong cavity field\ninhomogeneities, specific to superconducting circuit QED. It is therefore\nnecessary to introduce a formalism which bridges between these two domains. We\ndevelop a general method based on a photonic pseudo-potential to describe the\nelectric coupling between electrons in a nanocircuit and cavity photons. In\nthis picture, photons can induce simultaneously orbital energy shifts,\ntunneling, and local orbital transitions. We study in details the elementary\nexample of a single quantum dot with a single normal metal reservoir, coupled\nto a cavity. Photon-induced tunneling terms lead to a non-universal relation\nbetween the cavity frequency pull and the damping pull. Our formalism can also\nbe applied to multi quantum dot circuits, molecular circuits, quantum point\ncontacts, metallic tunnel junctions, and superconducting nanostructures\nenclosing Andreev bound states or Majorana bound states, for instance.",
        "positive": "Electron Transport in Double Quantum Dot governed by Nuclear Magnetic\n  Field: We investigate theoretically electron transfer in a doble dot in a situation\nwhere it is governed by nuclear magnetic field: This has been recently achieved\nin experiment. We show how to partially compensate the nuclear magnetic field\nto restore Spin Blockade."
    },
    {
        "anchor": "Undamped transverse electric mode in undoped two-dimensional tilted\n  Dirac cone materials: Transverse electric (TE) modes can not propagate through the conducting\nsolids. This is because the continuum of particle-hole excitations of\nconductors contaminates with the TE mode and dampes it out. But in solids\nhosting tilted Dirac cone (TDC) that admit a description in terms of a modified\nMinkowski spacetime, the new spacetime structure remedies this issue and\ntherefore a tilted Dirac cone material (TDM) supports the propagation of an\nundamped TE mode which is sustained by density fluctuations. The resulting TE\nmode propagates at fermionic velocities which strongly confines the mode to the\nsurface of the two-dimensional (2D) TDM.",
        "positive": "Polarization dependent photoemission as a probe of the magnetic ground\n  state in the layered ferromagnet VI3: Layered ferromagnets are thrilling materials from both a fundamental and\ntechnological point of view. VI3 is an interesting example, with a complex\nmagnetism that differentiates it from the first reported Cr based layered\nferromagnets. Here, we show in an indirect way through Angle Resolved\nPhotoemission Spectroscopy (ARPES) experiments, the importance of spin-orbit\ncoupling setting the electronic properties of this material. Our light\npolarized photoemission measurements point to a ground state with a half-filled\ne'_+- doublet, where a gap opening is triggered by spin-orbit coupling enhanced\nby electronic correlations."
    },
    {
        "anchor": "Tuning Phononic and Electronic Contributions of Thermoelectric in\n  defected S-Shape Graphene Nanoribbons: Thermoelectrics as a way to use waste heat, is essential in electronic\nindustries, but its low performance at operational temperatures makes it\ninappropriate in practical applications. Tailoring graphene can change its\nproperties. In this work, we are interested in studying the transport\nproperties of S-shape graphene structures with the single vacancy (SV) and\ndouble vacancy (DV) models. The structures are composed of a chiral part, which\nis an armchair graphene nanoribbon, and two zigzag graphene ribbons. We\ninvestigate the changes in the figure of merit by means of the Seebeck\ncoefficient, electronic conductance, and electronic and phononic conductances\nwith the vacancies in different device sizes. The transport properties of the\nsystem are studied by using the non-equilibrium Greens function method, so that\nthe related Hamiltonians (dynamical matrices) are obtained from the\ntight-binding (force constant) model. The maximum figure of merit (ZT) obtains\nfor the DVs in all lengths. Physical properties of such a system can be tuned\nby controlling various parameters such as the location and the type of the\ndefects, and the device size. Our findings show that lengthening the structure\ncan reduce phononic contribution, and single vacancies than double vacancies\ncan better distinguish between electronic thermal conductance behavior and\nelectronic conductance one. Namely, vacancy engineering can significantly\nincrease thermoelectric performance. In the large devices, the SVs can increase\nthe ZT up to 2.5 times.",
        "positive": "Reconfigurable quadruple quantum dots in a silicon nanowire transistor: We present a novel reconfigurable metal-oxide-semiconductor multi-gate\ntransistor that can host a quadruple quantum dot in silicon. The device consist\nof an industrial quadruple-gate silicon nanowire field-effect transistor.\nExploiting the corner effect, we study the versatility of the structure in the\nsingle quantum dot and the serial double quantum dot regimes and extract the\nrelevant capacitance parameters. We address the fabrication variability of the\nquadruple-gate approach which, paired with improved silicon fabrication\ntechniques, makes the corner state quantum dot approach a promising candidate\nfor a scalable quantum information architecture."
    },
    {
        "anchor": "Transport properties of armchair graphene nanoribbon junctions between\n  graphene electrodes: The transmission properties of armchair graphene nanoribbon junctions between\ngraphene electrodes are investigated by means of first-principles quantum\ntransport calculations. First the dependence of the transmission function on\nthe size of the nanoribbon has been studied. Two regimes are highlighted: for\nsmall applied bias transport takes place via tunneling and the length of the\nribbon is the key parameter that determines the junction conductance; at higher\napplied bias resonant transport through HOMO and LUMO starts to play a more\ndeterminant role, and the transport properties depend on the details of the\ngeometry (width and length) of the carbon nanoribbon. In the case of the\nthinnest ribbon it has been verified that a tilted geometry of the central\nphenyl ring is the most stable configuration. As a consequence of this rotation\nthe conductance decreases due to the misalignment of the $pi$ orbitals between\nthe phenyl ring and the remaining part of the junction. All the computed\ntransmission functions have shown a negligible dependence on different\nsaturations and reconstructions of the edges of the graphene leads, suggesting\na general validity of the reported results.",
        "positive": "The inverse thermal spin-orbit torque and the relation of the\n  Dzyaloshinskii-Moriya interaction to ground-state energy currents: Using the Kubo linear-response formalism we derive expressions to calculate\nthe heat current generated by magnetization dynamics in magnets with broken\ninversion symmetry and spin-orbit interaction (SOI). The effect of producing\nheat currents by magnetization dynamics constitutes the Onsager reciprocal of\nthe thermal spin-orbit torque (TSOT), i.e., the generation of torques on the\nmagnetization due to temperature gradients. We find that the energy current\ndriven by magnetization dynamics contains a contribution from the\nDzyaloshinskii-Moriya interaction (DMI), which needs to be subtracted from the\nKubo linear response of the energy current in order to extract the heat\ncurrent. We show that the expressions of the DMI coefficient can be derived\nelegantly from the DMI energy current. Guided by formal analogies between the\nBerry phase theory of DMI on the one hand and the modern theory of orbital\nmagnetization on the other hand we are led to an interpretation of the latter\nin terms of energy currents as well. Based on \\textit{ab-initio} calculations\nwe investigate the heat current driven by magnetization dynamics in Mn/W(001)\nmagnetic bilayers. We predict that fast domain walls drive strong ITSOT heat\ncurrents."
    },
    {
        "anchor": "Exact microscopic wave function for a topological quantum membrane: The higher dimensional quantum Hall liquid constructed recently supports\nstable topological membrane excitations. Here we introduce a microscopic\ninteracting Hamiltonian and present its exact ground state wave function. We\nshow that this microscopic ground state wave function describes a topological\nquantum membrane. We also construct variational wave functions for excited\nstates using the non-commutative algebra on the four sphere. Our approach\nintroduces a non-perturbative method to quantize topological membranes.",
        "positive": "Artificial molecular quantum rings under magnetic field influence: The ground states of few electrons confined in two vertically coupled quantum\nrings in the presence of an external magnetic field are studied systematically\nwithin the current spin-density functional theory. Electron-electron\ninteractions combined with inter-ring tunneling affects the electronic\nstructure and the persistent current. For small values of the external magnetic\nfield, we recover the zero magnetic field molecular quantum ring ground state\nconfigurations. Increasing the magnetic field many angular momentum, spin, and\niso-spin transitions are predicted to occur in the ground state. We show that\nthese transitions follow certain rules, which are governed by the parity of the\nnumber of electrons, the single particle picture, the Hund's rules and\nmany-body effects."
    },
    {
        "anchor": "Thermal conductivity of benzothieno-benzothiophene derivatives at the\n  nanoscale: We study by scanning thermal microscopy the nanoscale thermal conductance of\nfilms (40 to 400 nm thick) of [1]benzothieno[3,2-b][1]benzothiophene (BTBT) and\n2,7-dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT-C8). We demonstrate\nthat the out-of-plane thermal conductivity is significant along the interlayer\ndirection, larger for BTBT (0.63 +/- 0.12 W m-1 K-1) compared to C8-BTBT-C8\n(0.25 +/- 0.13 W m-1 K-1). These results are supported by molecular dynamics\ncalculations (Approach to Equilibrium Molecular Dynamics method) performed on\nthe corresponding molecular crystals. The calculations point to significant\nthermal conductivity (3D-like) values along the 3 crystalline directions, with\nanisotropy factors between the crystalline directions below 1.8 for BTBT and\nbelow 2.8 for C8-BTBT-C8, in deep contrast with the charge transport properties\nfeaturing a two-dimensional character for these materials. In agreement with\nthe experiments, the calculations yield larger values in BTBT compared to\nC8-BTBT-C8 (0.6-1.3 W m-1 K-1 versus 0.3-0.7 W m-1 K-1, respectively). The weak\nthickness dependence of the nanoscale thermal resistance is in agreement with a\nsimple analytical model.",
        "positive": "Polarization and entanglement spectrum in non-hermitian systems: The entanglement spectrum is a useful tool to study topological phases of\nmatter, and contains valuable information about the ground state of the system.\nHere, we study its properties for free non-Hermitian systems for both\npoint-gapped and line-gapped phases. While the entanglement spectrum only\nretains part of the topological information in the former case, it is very\nsimilar to Hermitian systems in the latter. In particular, it not only mimics\nthe topological edge modes, but also contains all the information about the\npolarization, even in systems that are not topological. Furthermore, we show\nthat the Wilson loop is equivalent to the many-body polarization and that it\nreproduces the phase diagram for the system with open boundaries, despite being\ncomputed for a periodic system."
    },
    {
        "anchor": "Evidence for spin current driven Bose-Einstein condensation of magnons: The quanta of magnetic excitations - magnons - are known for their unique\nability to undergo Bose-Einstein condensation at room temperature. This\nfascinating phenomenon reveals itself as a spontaneous formation of a\nmacroscopic coherent state under the influence of incoherent stimuli. Spin\ncurrents have been predicted to offer electronic control of magnon\nBose-Einstein condensates, but this phenomenon has not been experimentally\nevidenced up to now. Here we experimentally show that current-driven\nBose-Einstein condensation can be achieved in nanometer-thick films of magnetic\ninsulators with tailored dynamic magnetic nonlinearities and minimized\nmagnon-magnon interactions. We demonstrate that, above a certain threshold,\nmagnons injected by the spin current overpopulate the lowest-energy level\nforming a highly coherent spatially extended state. By accessing magnons with\nessentially different energies, we quantify the chemical potential of the\ndriven magnon gas and show that, at the critical current, it reaches the energy\nof the lowest magnon level. Our results pave the way for implementation of\nintegrated microscopic quantum magnonic and spintronic devices.",
        "positive": "Information transfer by vector spin chirality in finite magnetic chains: Vector spin chirality is one of the fundamental characteristics of complex\nmagnets. For a one-dimensional spin-spiral state it can be interpreted as the\nhandedness, or rotational sense of the spiral. Here, using spin-polarized\nscanning tunneling microscopy, we demonstrate the occurrence of an atomic-scale\nspin-spiral in finite individual bi-atomic Fe chains on the (5x1)-Ir(001)\nsurface. We show that the broken inversion symmetry at the surface promotes one\ndirection of the vector spin chirality, leading to a unique rotational sense of\nthe spiral in all chains. Correspondingly, changes in the spin direction of one\nchain end can be probed tens of nanometers away, suggesting a new way of\ntransmitting information about the state of magnetic objects on the nanoscale."
    },
    {
        "anchor": "Theory of AC quantum transport with fully electrodynamic coupling: With the continued scaling of microelectronic devices along with the growing\ndemand of high-speed wireless telecommunications technologies, there is\nincreasing need for high-frequency device modeling techniques that accurately\ncapture the quantum mechanical nature of charge transport in nanoscale devices\nalong with the dynamic fields that are generated. In an effort to fill this\ngap, we develop a simulation methodology that self-consistently couples AC\nnon-equilibrium Green functions (NEGF) with the full solution of Maxwell's\nequations in the frequency domain. We apply this technique to simulate\nradiation from a quantum-confined, quarter-wave, monopole antenna where the\nlength $L$ is equal to one quarter of the wavelength, $\\lambda_0$. Classically,\nsuch an antenna would have a narrower, more directed radiation pattern compared\nto one with $L \\ll \\lambda_0$, but we find that a quantum quarter-wave antenna\nhas no directivity gain compared to the classical solution. We observe that the\nquantized wave function within the antenna significantly alter the charge and\ncurrent density distribution along the length of the wire, which in turn\nmodifies the far-field radiation pattern from the antenna. These results show\nthat high-frequency radiation from quantum systems can be markedly different\nfrom classical expectations. Our method, therefore, will enable accurate\nmodeling of the next generation of high-speed nanoscale electronic devices.",
        "positive": "Theory of quantum Hall effect and high Landau levels: The angular momentum model which couples the spin and charge is discussed as\na possible theory of the quantum Hall effect. The high Landau level filling\nfractions 5/2, 7/3 and 8/3 are understood by this model. It is found that 7/3\nand 8/3 are the particle-hole conjugates and 5/2 arises due to a limiting level\nat 1/2 with Landau level number n=5 which makes the fraction as 5/2."
    },
    {
        "anchor": "Diluted magnetic semiconductor heterostructure AlSb/InAs/ZnMnTe with\n  giant Zeeman effect for two dimensional electrons in InAs: A new approach to the growth of diluted magnetic semiconductors with two\ndimensional electron gas in InAs quantum well has been developed. The method is\nbased on molecular-beam epitaxy of coherent \"hybrid\" AlSb/InAs/(Zn,Mn)Te\nheterostructures with a III-V/II-VI interface inside. The giant Zeeman\nsplitting of the InAs conduction band caused by exchange interaction with Mn2+\nions has been proved by measuring the microwave radiation induced spin\npolarized electric currents.",
        "positive": "Type-II Topological Dirac Semimetals: Theory and Materials Prediction\n  (VAl3 family): The discoveries of Dirac and Weyl semimetal states in spin-orbit compounds\nled to the realizations of elementary particle analogs in table-top\nexperiments. In this paper, we propose the concept of a three-dimensional\ntype-II Dirac fermion and identify a new topological semimetal state in the\nlarge family of transition-metal icosagenides, MA3 (M=V, Nb, Ta; A=Al, Ga, In).\nWe show that the VAl3 family features a pair of strongly Lorentz-violating\ntype-II Dirac nodes and that each Dirac node consists of four type-II Weyl\nnodes with chiral charge +/-1 via symmetry breaking. Furthermore, we predict\nthe Landau level spectrum arising from the type-II Dirac fermions in VAl3 that\nis distinct from that of known Dirac semimetals. We also show a topological\nphase transition from a type-II Dirac semimetal to a quadratic Weyl semimetal\nor a topological crystalline insulator via crystalline distortions. The new\ntype-II Dirac fermions, their novel magneto-transport response, the topological\ntunability and the large number of compounds make VAl3 an exciting platform to\nexplore the wide-ranging topological phenomena associated with\nLorentz-violating Dirac fermions in electrical and optical transport,\nspectroscopic and device-based experiments."
    },
    {
        "anchor": "Molecular simulation of nano-dispersed fluid phases: Fluid phase equilibria involving nano-dispersed phases, where at least one of\nthe coexisting phases is confined to a small volume, are investigated by\nmolecular dynamics simulation. Complementing previous studies on nanoscopic\ndroplets, simulation volumes containing a nanoscopic gas bubble surrounded by a\nsubsaturated liquid phase under tension, i.e. at negative pressure, are\nconducted in the canonical ensemble. The boundary conditions are chosen such\nthat the phase equilibrium at the curved interface is thermodynamically stable.\nTwo distinct size-dependent effects are found: Curvature induces a\nsubsaturation of the system, leading to a smaller liquid density. For the gas\nin the centre of the bubble, the small diameter has an additional obverse\neffect, increasing its density. The curvature dependence of the surface tension\nis discussed by evaluating average radial density profiles to obtain the excess\nequimolar radius, which is found to be positive, corresponding to a negative\nTolman length.",
        "positive": "Shedding light on the monolayer-WSe2 exciton's nature by optical\n  effective-mass measurements: Two-dimensional excitons formed in quantum materials such as monolayer\ntransition-metal dichalcogenides and their strong light-matter interaction have\nattracted unrivalled attention by the research community due to their\nextraordinarily large oscillator strength as well as binding energy, and the\ninherent spin-valley locking. Semiconducting few-layer and monolayer materials\nwith their sharp optical resonances such as WSe2 have been extensively studied\nand envisioned for applications in the weak as well as strong light-matter\ncoupling regimes, for effective nano-laser operation with various different\nstructures, and particularly for valleytronic nanophotonics motivated by the\ncircular dichroism. Many of these applications, which may benefit heavily from\nthe two-dimensional electronic quasiparticle's properties in such films,\nrequire controlling, manipulating and first of all understanding the nature of\nthe optical resonances that are attributed to exciton modes. While theory and\nprevious experiments have provided unique methods to the characterization and\nclassification efforts regarding the band structure and optical modes in 2D\nmaterials, here, we directly measure the quasiparticle energy-momentum\ndispersion for the first time. Our results for single-layer WSe2 clearly\nindicate an emission regime predominantly governed by free excitons, i.e.\nCoulomb-bound electron-hole pairs with centre-of-mass momentum and\ncorresponding effective mass. Besides uniquely evidencing the existence of free\nexcitons at cryogenic temperatures optically, the fading of the dispersive\ncharacter for increased temperatures or excitation densities reveals a\ntransition to a regime with profound role of charge-carrier plasma or localized\nexcitons regarding its emission, debunking the myth of free-exciton emission at\nelevated temperatures."
    },
    {
        "anchor": "Fabrication of Nano-Gapped Single-Electron Transistors for Transport\n  Studies of Individual Single-Molecule Magnets: Three terminal single-electron transistor devices utilizing Al/Al2O3 gate\nelectrodes were developed for the study of electron transport through\nindividual single-molecule magnets. The devices were patterned via multiple\nlayers of optical and electron beam lithography. Electromigration induced\nbreaking of the nanowires reliably produces 1-3 nm gaps between which the SMM\ncan be situated. Conductance through a single Mn12(3-thiophenecarboxylate)\ndisplays the coulomb blockade effect with several excitations within +/- 40\nmeV.",
        "positive": "Increased metallicity of Carbon nanotubes because of incorporation of\n  extended Stone-Wales' defects: an ab-initio real space approach: We propose an ab-initio combination of the Linear Muffin-Tin Orbital and the\nRecursion Methods to study the effect of extended Stone-Wales defects in single\nlayer Carbon nanotubes. We have successfully applied this to zigzag and\narmchair tubes. The methodology involves no intrinsic mean-field like\nassumptions or external parameter fitting. As defects proliferate, the low\ndensity of states near the Fermi levels of the pristine tubes is filled with\ndefect states. The increase of DOS at the Fermi level leads to enhanced\nconduction, which indicates enhanced metallicity due to SW defects in the\nnanotubes."
    },
    {
        "anchor": "Towards a quantum representation of the ampere using single electron\n  pumps: Electron pumps generate a macroscopic electric current by controlled\nmanipulation of single electrons. Despite intensive research towards a quantum\ncurrent standard over the last 25 years, making a fast and accurate quantised\nelectron pump has proved extremely difficult. Here we demonstrate that the\naccuracy of a semiconductor quantum dot pump can be dramatically improved by\nusing specially designed gate drive waveforms. Our pump can generate a current\nof up to 150 pA, corresponding to almost a billion electrons per second, with\nan experimentally demonstrated current accuracy better than 1.2 parts per\nmillion (ppm) and strong evidence, based on fitting data to a model, that the\ntrue accuracy is approaching 0.01 ppm. This type of pump is a promising\ncandidate for further development as a realisation of the SI base unit ampere,\nfollowing a re-definition of the ampere in terms of a fixed value of the\nelementary charge.",
        "positive": "Twisted Trilayer Graphene: a Precisely Tunable Platform for Correlated\n  Electrons: We introduce twisted trilayer graphene (tTLG) with two independent twist\nangles as an ideal system for the precise tuning of the electronic interlayer\ncoupling to maximize the effect of correlated behaviors. As established by\nexperiment and theory in the related twisted bilayer graphene system, van Hove\nsingularities (VHS) in the density of states can be used as a proxy of the\ntendency for correlated behaviors. To explore the evolution of VHS in the\ntwist-angle phase space of tTLG, we present a general low-energy electronic\nstructure model for any pair of twist angles. We show that the basis of the\nmodel has infinite dimensions even at a finite energy cutoff and that no\nBrillouin zone exists even in the continuum limit. Using this model, we\ndemonstrate that the tTLG system exhibits a wide range of magic angles at which\nVHS merge and the density of states has a sharp peak at the charge-neutrality\npoint through two distinct mechanisms: the incommensurate perturbation of\ntwisted bilayer graphene's flat bands or the equal hybridization between two\nbilayer moir\\'e superlattices."
    },
    {
        "anchor": "Analytical description of ballistic spin currents and torques in\n  magnetic tunnel junctions: In this work we demonstrate explicit analytical expressions for both charge\nand spin currents which constitute the 2x2 spinor in magnetic tunnel junctions\nwith noncollinear magnetizations under applied voltage. The calculations have\nbeen performed within the free electron model in the framework of the Keldysh\nformalism and WKB approximation. We demonstrate that spin/charge currents and\nspin transfer torques are all explicitly expressed through only three\nirreducible quantities, without further approximations. The conditions and\nmechanisms of deviation from the conventional sine angular dependence of both\nspin currents and torques are shown and discussed. It is shown in the thick\nbarrier approximation that all tunneling transport quantities can be expressed\nin an extremely simplified form via Slonczewski spin polarizations and our\neffective spin averaged interfacial transmission probabilities and effective\nout-of-plane polarizations at both interfaces. It is proven that the latter\nplays a key role in the emergence of perpendicular spin torque as well as in\nthe angular dependence character of all spin and charge transport considered.\nIt is demonstrated directly also that for any applied voltage, the parallel\ncomponent of spin current at the FM/I interface is expressed via collinear\nlongitudinal spin current components. Finally, spin transfer torque behavior is\nanalyzed in a view of transverse characteristic length scales for spin\ntransport.",
        "positive": "Intrinsic 2D-XY ferromagnetism in a van der Waals monolayer: Long before the recent fascination with two-dimensional materials, the\ncritical behaviour and universality scaling of phase transitions in\nlow-dimensional systems has been a topic of great interest. Particularly\nintriguing is the case of long-range magnetic order in two dimensions, once\nconsidered to be excluded in systems with continuous symmetry by the\nHohenberg-Mermin-Wagner theorem. While an out-of-plane anisotropy has been\nshown to stabilize 2D magnetic order, this proof has remained elusive for a 2D\nmagnet with in-plane rotational symmetry. Here, we construct a nearly ideal\neasy-plane system, a CrCl3 monolayer grown on Graphene/6H-SiC (0001), and\nunambiguously demonstrate robust in-plane ferromagnetic ordering with a\ncritical scaling behaviour characteristic of a 2D-XY system. These observations\nsuggest the first realization of a finite-size Berezinskii-Kosterlitz-Thouless\n(BKT) phase transition in a large-area, quasi-freestanding, van der Waals\nmonolayer magnet with a XY universality class; and further constitute an ideal\nplatform to study exotic phenomena like superfluid spin transport or 2D\ntopological in-plane spin textures -- such as merons."
    },
    {
        "anchor": "Correlation lengths of Wigner crystal order in two dimensional electron\n  system at high magnetic field: The insulator terminating the fractional quantum Hall series at low Landau\nlevel filling \\nu is generally taken to be a pinned Wigner crystal (WC), and\nexhibits a microwave resonance that is interpreted as a WC pinning mode.\nSystematically studying the resonance in a high quality sample for carrier\ndensities, n, between 1.8 and 5.7 x 10^{10} cm^-2, we find maxima in resonance\npeak frequency, f_pk, vs magnetic field, B. L, the domain size, or correlation\nlength of Wigner crystalline order, is calculated from f_pk. For each n, L vs\n\\nu tends at low \\nu toward a straight line with intercept; the linear fit is\naccurate over as much as a factor of 5 range of \\nu. We interpret the striking\nlinear behavior as due to B compressing the electron wavefunctions, to alter\nthe effective electron-impurity interaction.",
        "positive": "Antiferromagnet-Mediated Spin Transfer Between Metal and Ferromagnet: We develop a theory for spin transported by coherent Neel dynamics through an\nantiferromagnetic insulator coupled to a ferromagnetic insulator on one side\nand a current-carrying normal metal with strong spin-orbit coupling on the\nother. The ferromagnet is considered within the mono-domain limit and we assume\nits coupling to the local antiferromagnet Neel order at the\nferromagnet|antiferromagnet interface through exchange coupling. Coupling\nbetween the charge current and the local Neel order at the other interface is\ndescribed using spin Hall phenomenology. Spin transport through the\nantiferromagnet, assumed to possess an easy-axis magnetic anisotropy, is solved\nwithin the adiabatic approximation and the effect of spin current flowing into\nthe ferromagnet on its resonance linewidth is evaluated. Onsager reciprocity is\nused to evaluate the inverse spin Hall voltage generated across the metal by a\ndynamic ferromagnet as a function the antiferromagnet thickness."
    },
    {
        "anchor": "Exciton Condensation in Landau Levels of Quantum Spin Hall Insulators: The interplay of band topology and electron interactions can lead to novel\nquantum states of matter. In this work, we theoretically study the quantum spin\nHall insulator (QSHI) in a perpendicular magnetic field. In the noninteracting\ncase, the QSHI with space inversion and uniaxial spin rotation symmetries\nundergoes a topological transition into a normal insulator phase at a critical\nmagnetic field $B_{\\mathrm{c}}$. The exciton condensation in the lowest Landau\nlevels is triggered by Coulomb interactions in the vicinity of $B_{\\mathrm{c}}$\nand spontaneously breaks the inversion and the spin rotation symmetries. We\npropose that the electron spin resonance spectroscopy can directly probe the\nexciton condensation order. Our results should apply to the InAs/GaSb quantum\nwells and other QSHIs.",
        "positive": "Blueprint for deterministic all-optical switching of magnetization: We resolve a significant controversy about how to understand and engineer\nsingle-shot all-optical switching of magnetization in ferrimagnets using femto-\nor picosecond-long heat pulses. By realistically modelling a generic\nferrimagnet as two coupled macrospins, we comprehensively show that the net\nmagnetization can be reversed via different pathways, using a heat pulse with\nduration spanning all relevant timescales within the non-adiabatic limit. This\nconceptual understanding is fully validated by experiments studying the\nmaterial and optical limits at which the switching process in GdFeCo alloys\nloses its reliability. Our interpretation and results constitute a blueprint\nfor understanding how deterministic all-optical switching can be achieved in\nalternative ferrimagnets using short thermal pulses."
    },
    {
        "anchor": "Polaritonic spectroscopy of intersubband transitions: We report on an extensive experimental study of intersubband excitations in\nthe THz range arising from the coupling between a quantum well and a\nzero-dimensional metal-metal microcavities. Because of the conceptual\nsimplicity of the resonators we obtain an extremely predictable and\ncontrollable system to investigate light-matter interaction. The experimental\ndata is modelled by combining a quantum mechanical approach with an effective\nmedium electromagnetic simulation that allows us to take into account the\nlosses of the system. By comparing our modelling with the data we are able to\nretrieve microscopic information, such as the electronic populations on\ndifferent subbands as a function of the temperature. Our modelling approach\nsets the base of a designer tool for intersubband light-matter coupled systems.",
        "positive": "Multiscale Simulation of Quantum Nanosystems: Plasmonics of Silver\n  Particles: Quantum nanosystems involve the coupled dynamics of fermions or bosons across\nmultiple scales in space and time. Examples include quantum dots,\nsuperconducting or magnetic nanoparticles, molecular wires, and graphene\nnanoribbons. The number (10^3 to 10^9) of electrons in assemblies of interest\nhere presents a challenge for traditional quantum computations. However,\nresults from deductive multiscale analysis yield coarse-grained wave equation\nthat capture the longer-scale quantum dynamics of these systems; a companion\nshort-scale equation is also developed that allows for the construction of\neffective masses and interactions involved in the coarse-grained wave equation.\nThe theory suggest an efficient algorithm for simulating quantum nanosystem\nwhich is implemented here. A variational Monte Carlo method is used to simulate\nthe co-evolution of long- and short-scale processes. The approach does not\nrequire experimental data for calibration. It is validated via experimental\ndata and TDDFT predictions on the nanoparticle size dependence of the plasmon\nspectrum."
    },
    {
        "anchor": "Stark effect in GaN/AlN nanowire heterostructures: Influence of strain\n  relaxation and surface states: We model the quantum confined Stark effect in AlN/GaN/AlN heterostructures\ngrown on top of [0001]-oriented GaN nanowires. The pyro- and piezoelectric\nfield are computed in a self-consistent approach, making no assumption about\nthe pinning of the Fermi level, but including an explicit distribution of\nsurface states which can act as a source or trap of carriers. We show that the\npyro- and piezoelectric field bends the conduction and valence bands of GaN and\nAlN and transfers charges from the top surface of the nanowire to an electron\ngas below the heterostructure. As a consequence, the Fermi level is likely\npinned near the valence band of AlN at the top surface. The electron gas and\nsurface charges screen the electric field, thereby reducing the Stark effect.\nThe efficient strain relaxation further weakens the piezoelectric polarization.\nWe compute the electronic properties of the heterostructures with a sp3d5s*\ntight-binding model, and compare the theoretical predictions with the available\nexperimental data.",
        "positive": "Oscillating chiral currents in nanotubes: a route to nanoscale magnetic\n  test tubes: With a view to optimising the design of carbon-nanotube (CNT) windmills and\nto maximising the internal magnetic field generated by chiral currents, we\npresent analytical results for the group velocity components of an electron\nflux through chiral carbon nanotubes. Chiral currents are shown to exhibit a\nrich behaviour and can even change sign and oscillate as the energy of the\nelectrons is increased. We find that the transverse velocity and associated\nangular momentum of electrons is a maximum for non-metallic CNTs with a chiral\nangle of 18$^o$. Such CNTs are therefore the optimal choice for CNT windmills\nand also generate the largest internal magnetic field for a given longitudinal\ncurrent. For a longitudinal current of order $10^{-4}$ amps, this field can be\nof order $10^{-1}$Teslas, which is sufficient to produce interesting spintronic\neffects and a significant contribution to the self inductance."
    },
    {
        "anchor": "Phase-coherent loops in selectively-grown topological insulator\n  nanoribbons: Universal conductance fluctuations and the weak antilocalization effect are\ndefect structure specific fingerprints in the magnetoconductance that are\ncaused by electron interference. Experimental evidence is presented that the\nconductance fluctuations in the present topological insulator\n(Bi$_{0.57}$Sb$_{0.43}$)$_2$Te$_3$ nanoribbons which are selectively grown by\nmolecular beam epitaxy are caused by well-defined and sharply resolved\nphase-coherent loops. From measurements at different magnetic field tilt angles\nwe deduced that these loops are preferentially oriented parallel to the\nquintuple layers of the topological insulator material. Both from a theoretical\nanalysis of universal conductance fluctuations and from weak antilocalization\nmeasured at low temperature the electronic phase-coherence lengths $l_\\phi$ are\nextracted, which is found to be larger in the former case. Possible reasons for\nthis deviation are discussed.",
        "positive": "Observation of the Dirac fluid and the breakdown of the Wiedemann-Franz\n  law in graphene: Interactions between particles in quantum many-body systems can lead to\ncollective behavior described by hydrodynamics. One such system is the\nelectron-hole plasma in graphene near the charge neutrality point which can\nform a strongly coupled Dirac fluid. This charge neutral plasma of\nquasi-relativistic fermions is expected to exhibit a substantial enhancement of\nthe thermal conductivity, due to decoupling of charge and heat currents within\nhydrodynamics. Employing high sensitivity Johnson noise thermometry, we report\nthe breakdown of the Wiedemann-Franz law in graphene, with a thermal\nconductivity an order of magnitude larger than the value predicted by Fermi\nliquid theory. This result is a signature of the Dirac fluid, and constitutes\ndirect evidence of collective motion in a quantum electronic fluid."
    },
    {
        "anchor": "Detection of Photons Emitted from Single Er Atoms in Energy Dispersive\n  X-ray Spectroscopy: Detecting the photons emitted from single quantum objects is highly desired\nto diagnose nano-scale devices. It has been, however, believed very difficult\nto sense single atoms in optical spectroscopy due to the inferior detection\nefficiency. We demonstrate here the successful detection of the characteristic\nx-ray signals from single Er atoms in energy dispersive x-ray spectroscopy\n(EDX). Highly focused electron probe in an aberration-corrected scanning\ntransmission electron microscope (STEM) was used to excite the single Er atoms\naligned in carbon cages, namely the peapod. The intensities of Er L and M lines\nfrom single Er atom were found to be 104 ~ 105 times less than that of the\nN-edge of electron energy-loss spectroscopy (EELS), suggesting the intrinsic\ndifficulty to sense single atoms in X-ray spectroscopy. Nevertheless, this work\nwill certainly ensure the possibilities to obtain X-ray spectra from single\natoms and to evaluate the fluorescence yield at single atom basis, therefore\nthe technique will likely find wide fields of applications in nano-physics\nresearch.",
        "positive": "Two-dimensional inversion symmetry as the fundamental symmetry of\n  incompressible quantum Hall fluids: Two dimensional inversion symmetry ($180^{\\circ}$ rotations in the ``Hall\nplane'' that hosts the incompressible electron fluid that exhibits the\nquantized Hall effect) is identified as its fundamental unbroken symmetry. A\nconsequence is that the integers $p$ and $q$ which define both the Landau level\nfilling factor $\\nu$ = $p/q$ and the elementary fractional charge $\\pm e/q$ of\ntopological excitations, cannot have a common divisor greater than 2."
    },
    {
        "anchor": "Chiral selection rules for multi-photon processes in two-dimensional\n  honeycomb materials: We examined the chirality dependent optical selection rules in\ntwo-dimensional monolayer materials with the honeycomb lattice, and based on\nsymmetry argument, we generalized these rules to multi-photon transitions of\narbitrary orders. We also presented the phase relations between incident and\noutgoing photons in such processes. The results agreed nicely with our\nexperimental observations of second and third harmonic generations. In\nparticular, we demonstrated that the phase relation of chiral second harmonic\ngeneration can serve as a handy tool for imaging domains and domain boundaries\nof these monolayers. Our results can benefit future studies on chirality\nrelated optical phenomena and opto-electronic applications of such materials.",
        "positive": "Marcus rate for electron transfer and the Goldilocks principle: We examine electron transfer between two quantum states in the presence of a\ndissipative environment represented as a set of independent harmonic\noscillators. For this simple model, the Marcus transfer rates can be derived\nand we show that these rates are associated to an explicit expression for the\nenvironment correlation time. We demonstrate that as a manifestation of the\nGoldilocks principle, the optimal transfer is governed by a single parameter\nwhich is equal to just the inverse root square of two."
    },
    {
        "anchor": "Semiclassical Density Functional Theory: Strutinsky Energy Corrections\n  in Quantum Dots: We develop a semiclassical density functional theory in the context of\nquantum dots. Coulomb blockade conductance oscillations have been measured in\nseveral experiments using nanostructured quantum dots. The statistical\nproperties of these oscillations remain puzzling, however, particularly the\nstatistics of spacings between conductance peaks. To explore the role that\nresidual interactions may play in the spacing statistics, we consider many-body\nsystems which include electron-electron interactions through an explicit\ndensity functional. First, we develop an approximate series expansion for\nobtaining the ground state using the idea of the Strutinsky shell correction\nmethod. Next, we relate the second-order semiclassical corrections to the\nscreened Coulomb potential. Finally, we investigate the validity of the\napproximation method by numerical calculation of a one-dimensional model\nsystem, and show the relative magnitudes of the successive terms as a function\nof particle number.",
        "positive": "Strain-induced spatial and spectral isolation of quantum emitters in\n  mono- and bi-layer WSe2: Two-dimensional transition metal dichalcogenide semiconductors are intriguing\nhosts for quantum light sources due to their unique opto-electronic properties.\nHere we report that strain gradients induced by substrate patterning result in\nspatially and spectrally isolated quantum emitters in mono- and bi-layer WSe2.\nBy correlating localized excitons with localized strain-variations, we show\nthat the quantum emitter emission energy can be red-tuned up to a remarkable\n~170 meV. We probe the fine-structure, magneto-optics, and second order\ncoherence of a strained emitter. These results raise the prospect to\nstrain-engineer quantum emitter properties and deterministically create arrays\nof quantum emitters in two-dimensional semiconductors."
    },
    {
        "anchor": "Regular atomic narrowing of Ni, Fe and V nanowires resolved by 2D\n  correlation analysis: We present a novel statistical method for the study of stable atomic\nconfigurations in breaking nanowires based on the 2D cross-correlation analysis\nof conductance versus electrode separation traces. Applying this method, we can\nclearly resolve the typical evolutions of the conductance staircase in some\ntransition metal nanojunctions (Ni, Fe, V) up to high conductance values. In\nthese metals our analysis demonstrates a very well ordered atomic narrowing of\nthe nanowire, indicating a very regular, stepwise decrease of the number of\natoms in the minimal cross section of the junction, in contrast to the majority\nof the metals. All these features are hidden in traditional conductance\nhistograms.",
        "positive": "Electrically controlled emission from singlet and triplet exciton\n  species in atomically thin light emitting diodes: Excitons are composite bosons that can feature spin singlet and triplet\nstates. In usual semiconductors, without an additional spin-flip mechanism,\ntriplet excitons are extremely inefficient optical emitters. Transition metal\ndichalcogenides (TMDs), with their large spin-orbit coupling, have been of\nspecial interest for valleytronic applications for their coupling of circularly\npolarized light to excitons with selective valley and spin$^{1-4}$. In\natomically thin MoSe$_2$/WSe$_2$ TMD van der Waals (vdW) heterostructures, the\nunique atomic registry of vdW layers provides a quasi-angular momentum to\ninterlayer excitons$^{5,6}$, enabling emission from otherwise dark spin triplet\nexcitons. Here, we report electrically tunable spin singlet and triplet exciton\nemission from atomically aligned TMD heterostructures. We confirm the spin\nconfigurations of the light-emitting excitons employing magnetic fields to\nmeasure effective exciton g-factors. The interlayer tunneling current across\nthe TMD vdW heterostructure enables the electrical generation of singlet and\ntriplet exciton emission in this atomically thin PN junction. We demonstrate\nelectrically tunability between the singlet and triplet excitons that are\ngenerated by charge injection. Atomically thin TMD heterostructure light\nemitting diodes thus enables a route for optoelectronic devices that can\nconfigure spin and valley quantum states independently by controlling the\natomic stacking registry."
    },
    {
        "anchor": "Gate fidelity and coherence of an electron spin in a Si/SiGe quantum dot\n  with micromagnet: The gate fidelity and the coherence time of a qubit are important benchmarks\nfor quantum computation. We construct a qubit using a single electron spin in a\nSi/SiGe quantum dot and control it electrically via an artificial spin-orbit\nfield from a micromagnet. We measure an average single-qubit gate fidelity of\n$\\approx$ 99$\\%$ using randomized benchmarking, which is consistent with\ndephasing from the slowly evolving nuclear spins in substrate. The coherence\ntime measured using dynamical decoupling extends up to $\\approx$ 400 $\\mu$s for\n128 decoupling pulses, with no sign of saturation. We find evidence that the\ncoherence time is limited by noise in the 10 kHz $-$ 1 MHz range, possibly\nbecause charge noise affecting the spin via the micromagnet gradient. This work\nshows that an electron spin in a Si/SiGe quantum dot is a good candidate for\nquantum information processing as well as for a quantum memory, even without\nisotopic purification.",
        "positive": "Macroscopic time reversal symmetry breaking by staggered spin-momentum\n  interaction: Time-reversal (T) symmetry breaking is a fundamental physics concept\nunderpinning a broad science and technology area, including topological\nmagnets, axion physics, dissipationless Hall currents, or spintronic memories.\nA best known conventional model of macroscopic T-symmetry breaking is a\nferromagnetic order of itinerant Bloch electrons with an isotropic spin\ninteraction in momentum space. Anisotropic electron interactions, on the other\nhand, have been a domain of correlated quantum phases, such as the T-invariant\nnematics or unconventional superconductors. Here we report discovery of a\nbroken-T phase of itinerant Bloch electrons with an unconventional anisotropic\nspin-momentum interaction, whose staggered nature leads to the formation of two\nferromagnetic-like valleys in the momentum space with opposite spin splittings.\nWe describe qualitatively the effect by deriving a non-relativistic\nsingle-particle Hamiltonian model. Next, we identify the unconventional\nstaggered spin-momentum interaction by first-principles electronic structure\ncalculations in a four-sublattice antiferromagnet Mn5Si3 with a collinear\ncheckerboard magnetic order. We show that the staggered spin-momentum\ninteraction is set by nonrelativistic spin-symmetries which were previously\nomitted in relativistic physics classifications of spin interactions and\ntopological quasiparticles. Our measurements of a spontaneous Hall effect in\nepilayers of antiferromagnetic Mn5Si3 with vanishing magnetization are\nconsistent with our theory predictions. Bloch electrons with the unconventional\nstaggered spin interaction, compatible with abundant low atomic-number\nmaterials, strong spin-coherence, and collinear antiferromagnetic order open\nunparalleled possibilities for realizing T-symmetry broken spin and topological\nquantum phases."
    },
    {
        "anchor": "Measuring topological invariants from generalized edge states in\n  polaritonic quasicrystals: We investigate the topological properties of Fibonacci quasicrystals using\ncavity polaritons. Composite structures made of the concatenation of two\nFibonacci sequences allow investigating generalized edge states forming in the\ngaps of the fractal energy spectrum. We employ these generalized edge states to\ndetermine the topological invariants of the quasicrystal. When varying a\nstructural degree of freedom (phason) of the Fibonacci sequence, the edge\nstates spectrally traverse the gaps, while their spatial symmetry switches: the\nperiodicity of this spectral and spatial evolution yields direct measurements\nof the gap topological numbers. The topological invariants that we determine\ncoincide with those assigned by the gap-labeling theorem, illustrating the\ndirect connection between the fractal and topological properties of Fibonacci\nquasicrystals.",
        "positive": "Tailoring Drug Mobility by Photothermal Heating of Graphene Plasmons: We propose a theoretical approach to quantitatively determine the\nphotothermally driven enhancement of molecular mobility of\ngraphene-indomethacin mixtures under infrared laser irradiation. Graphene\nplasmons absorb incident electromagnetic energy and dissipate them into heat.\nThe absorbed energy depends on optical properties of graphene plasmons, which\nare sensitive to structural parameters, and concentration of plasmonic\nnanostructures. By using theoretical model, we calculate temperature gradients\nof the bulk drug with different concentrations of graphene plasmons. From\nthese, we determine the temperature dependence of structural molecular\nrelaxation and diffusion of indomethacin and find how the heating process\nsignificantly enhances the drug mobility."
    },
    {
        "anchor": "Reconfigurable Boolean Logic using Magnetic Single-Electron Transistors: We propose a novel hybrid single-electron device for reprogrammable low-power\nlogic operations, the magnetic single-electron transistor (MSET). The device\nconsists of an aluminium single-electron transistors with a GaMnAs magnetic\nback-gate. Changing between different logic gate functions is realized by\nreorienting the magnetic moments of the magnetic layer which induce a voltage\nshift on the Coulomb blockade oscillations of the MSET. We show that we can\narbitrarily reprogram the function of the device from an n-type SET for\nin-plane magnetization of the GaMnAs layer to p-type SET for out-of-plane\nmagnetization orientation. Moreover, we demonstrate a set of reprogrammable\nBoolean gates and its logical complement at the single device level. Finally,\nwe propose two sets of reconfigurable binary gates using combinations of two\nMSETs in a pull-down network.",
        "positive": "Cooperative emission mediated by cooperative energy transfer to a\n  plasmonic antenna: We develop a theory of cooperative emission mediated by cooperative energy\ntransfer (CET) from an ensemble of quantum emitters (QE) to plasmonic antenna\nat a rate equal to the sum of individual QE-plasmon energy transfer rates. If\nthe antenna radiation efficiency is sufficiently high, the transferred energy\nis radiated away at approximately the same cooperative rate that scales with\nthe ensemble size. We derive explicit expressions, in terms of local fields,\nfor cooperative Purcell factor and enhancement factor for power spectrum valid\nfor plasmonic structures of any shape with characteristic size smaller than the\nradiation wavelength. The radiated power spectrum retains the plasmon resonance\nlineshape with overall amplitude scaling with the ensemble size. If QEs are\nlocated in a region with nearly constant plasmon local density of states\n(LDOS), e.g., inside a plasmonic nanocavity, we demonstrate that the CET rate\nscales linearly with the number of excited QEs, consistent with the experiment,\nand can be tuned in a wide range by varying the excitation power. For QEs\ndistributed in an extended region saturating the plasmon mode volume, we show\nthat the cooperative Purcell factor has universal form independent of the\nsystem size. The CET mechanism incorporates the plasmon LDOS enhancement as\nwell, giving rise to possibilities of controlling the emission rate beyond\nfield enhancement limits."
    },
    {
        "anchor": "Floquet metal to insulator phase transitions in semiconductor nanowires: We study steady-states of semiconductor nanowires subjected to strong\nresonant time-periodic drives. The steady-states arise from the balance between\nelectron-phonon scattering, electron-hole recombination via photo-emission, and\nAuger scattering processes. We show that tuning the strength of the driving\nfield drives a transition between an electron-hole metal (EHM) phase and a\nFloquet insulator (FI) phase. We study the critical point controlling this\ntransition. The EHM-to-FI transition can be observed by monitoring the presence\nof peaks in the density-density response function which are associated with the\nFermi momentum of the EHM phase, and are absent in the FI phase. Our results\nmay help guide future studies towards inducing novel non-equilibrium phases of\nmatter by periodic driving.",
        "positive": "Surface dissipation in nanoelectromechanical systems: Unified\n  description with the standard tunneling model and effects of metallic\n  electrodes: By modifying and extending recent ideas [C. Seoanez et al., Europhys. Lett.\n78, 60002 (2007)], a theoretical framework to describe dissipation processes in\nthe surfaces of vibrating micro- and nanoelectromechanical devices, thought to\nbe the main source of friction at low temperatures, is presented. Quality\nfactors as well as frequency shifts of flexural and torsional modes in doubly\nclamped beams and cantilevers are given, showing the scaling with dimensions,\ntemperature, and other relevant parameters of these systems. Full agreement\nwith experimental observations is not obtained, leading to a discussion of\nlimitations and possible modifications of the scheme to reach a quantitative\nfitting to experiments. For nanoelectromechanical systems covered with metallic\nelectrodes, the friction due to electrostatic interaction between the flowing\nelectrons and static charges in the device and substrate is also studied."
    },
    {
        "anchor": "Spin-induced anomalous magnetoresistance at the (100) surface of\n  hydrogen-terminated diamond: We report magnetoresistance measurements of hydrogen-terminated\n(100)-oriented diamond surfaces where hole carriers are accumulated using an\nionic-liquid-gated field-effect-transistor technique. Unexpectedly, the\nobserved magnetoresistance is positive within the range of 2<T<10 K and -7<B<7\nT, in striking contrast to the negative magnetoresistance previously detected\nfor similar devices with (111)-oriented diamond surfaces. Furthermore we find:\n1) magnetoresistance is orders of magnitude larger than that of the classical\norbital magnetoresistance; 2) magnetoresistance is nearly independent of the\ndirection of the applied magnetic field; 3) for the in-plane field, the\nmagnetoresistance ratio defined as [rho(B)-rho(0)]/rho(0) follows a universal\nfunction of B/T. These results indicate that the spin degree of freedom of hole\ncarriers plays an important role in the surface conductivity of\nhydrogen-terminated (100) diamond.",
        "positive": "Phase Transitions in the Bilayer $\u03bd=2/3$ Quantum Hall Effect: We measured the magnetoresistance of bilayer quantum Hall (QH) effects at the\nfractional filling factor $\\nu =2/3$ by changing the total electron density and\nthe density difference between two layers. Three different QH states were\nseparated by two types of phase transition: One is the spin transition and the\nother is the pseudospin transition. In addition, two different hystereses were\ndetected, one of which is specific to bilayer systems. The phase transitions\nand the hystereses are described well by a composite fermion model extended to\na bilayer system."
    },
    {
        "anchor": "Observation of anti-levitation of Landau levels in vanishing magnetic\n  fields: We report an anti-levitation behavior of Landau levels in vanishing magnetic\nfields in a high quality hetero-junction insulated-gated field-effect\ntransistor. We found, in the Landau fan diagram of electron density versus\nmagnetic field, the positions of the magneto-resistance minima at Landau level\nfillings \\nu=4, 5, 6 move below the 'traditional' Landau level line to lower\nelectron densities. Moreover, the even and odd filling factors show\nquantitatively different behaviors in anti-levitation, suggesting that the\nexchange interactions may be important.",
        "positive": "Small-Capacitance Josephson Junctions: One-Dimensional Arrays and Single\n  Junctions: We review experiments on small-capacitance Josephson junctions. When the\nJosephson junction is fabricated in the configuration of dc superconducting\nquantum interference device (SQUID), the Josephson coupling can be tuned IN\nSITU with an external magnetic field. The electrical transport properties of\none-dimensional arrays of small-capacitance dc SQUIDs have been investigated in\norder to study the superconductor-insulator transition. The arrays have also\nbeen used to bias a single Josephson junction, and a clear Coulomb blockade of\nCooper-pair tunneling has been observed in the single junction."
    },
    {
        "anchor": "Electronic and spin properties of hole point contacts: We have studied theoretically the effect of a tuneable lateral confinement on\ntwo-dimensional hole systems realised in III-V semiconductor heterostructures.\nBased on the 4x4 Luttinger description of the valence band, we have calculated\nquasi-onedimensional (quasi-1D) hole subband energies and anisotropic Lande\ng-factors. Confinement-induced band mixing results in the possibility to\nmanipulate electronic and spin properties of quasi-1D hole states over a much\nwider range than is typically possible for confined conduction-band electrons.\nOur results are relevant for recent experiments where source-drain-bias\nspectroscopy was used to measure Zeeman splitting of holes in p-type quantum\npoint contacts.",
        "positive": "Coherent and Dissipative Cavity Magnonics: Strong interactions between magnetic materials and electrodynamic cavities\nmix together spin and photon properties, producing unique hybridized behaviour.\nThe study of such coupled spin-photon systems, known as cavity magnonics, is\nmotivated by the flexibility and controllability of these hybridized states for\nspintronic and quantum information technologies. In this tutorial we examine\nand compare both coherent and dissipative interactions in cavity magnonics. We\nbegin with a familiar case study, the coupled harmonic oscillator, which\nprovides insight into the unique characteristics of coherent and dissipative\ncoupling. We then examine several canonical cavity magnonic systems,\nhighlighting the requirements for different coupling mechanisms, and conclude\nwith recent applications of spin-photon hybridization, for example, the\ndevelopment of quantum transducers, memory architectures, isolators and\nenhanced sensing."
    },
    {
        "anchor": "Defining and controlling double quantum dots in single-walled carbon\n  nanotubes: We report the experimental realization of double quantum dots in\nsingle-walled carbon nanotubes. The device consists of a nanotube with source\nand drain contact, and three additional top-gate electrodes in between. We show\nthat, by energizing these top-gates, it is possible to locally gate a nanotube,\nto create a barrier, or to tune the chemical potential of a part of the\nnanotube. At low temperatures we find (for three different devices) that in\ncertain ranges of top-gate voltages our device acts as a double quantum dot,\nevidenced by the typical honeycomb charge stability pattern.",
        "positive": "Unusual Electronic excitations in ABA trilayer graphene: The tight-binding model is closely associated with the modified random-phase\napproximation to thoroughly explore the electron-electron interactions in\ntrilayer AB-stacked graphene. The intralayer and interlayer atomic/Coulomb\ninteractions dominate the collective and electron-hole excitations. The unusual\nenergy bands are directly reflected in the diverse transferred\nmomentum-frequency phase diagrams. There exist three kinds of plasmon modes\nduring the variation of the doping level, being accompanied with the\ncomplicated intraband and interband single-particle excitations. The excitation\nbehaviors are greatly diversified by the number of layers. The theoretical\npredictions require the high-resolution experimental examinations."
    },
    {
        "anchor": "Missing 2k_F Response for Composite Fermions in Phonon Drag: The response of composite Fermions to large wavevector scattering has been\nstudied through phonon drag measurements. While the response retains\nqualitative features of the electron system at zero magnetic field, notable\ndiscrepancies develop as the system is varied from a half-filled Landau level\nby changing density or field. These deviations, which appear to be inconsistent\nwith the current picture of composite Fermions, are absent if half-filling is\nmaintained while changing density. There remains, however, a clear deviation\nfrom the temperature dependence anticipated for 2k_F scattering.",
        "positive": "Fully superconducting Bloch-oscillating transistor: Amplification and\n  bifurcation based on Bloch oscillations and counterflowing Cooper pairs: The Bloch-oscillating transistor (BOT) is an amplifier that utilizes\nsemiclassical dynamics of states in energy bands under traveling quasimomentum.\nIn a BOT, a single quasiparticle tunneling across a base tunnel junction\nswitches the state of a superconducting tunnel junction to a lower Bloch band,\ntriggering a series of resonant Cooper-pair tunnelings through an emitter\nJosephson junction (Bloch oscillations). Here, we investigate experimentally\nand theoretically an alternative realization of this device, based only on\nsuperconducting tunnel junctions. We discover new amplification schemes, where\nthe periodic motion of the quasimomentum is used to control charge transport\nbetween the electrodes. Remarkable, in operation the resonant Cooper-pair\ntransport across the base Josephson junction occurs repeatedly to two opposite\ndirections."
    },
    {
        "anchor": "Quantum Necking in Stressed Metallic Nanowires: When a macroscopic metallic wire is subject to tensile stress, it necks down\nsmoothly as it elongates. We show that nanowires with radii comparable to the\nFermi wavelength display remarkably different behavior. Using concepts from\nfluid dynamics, a PDE for nanowire shape evolution is derived from a\nsemiclassical energy functional that includes electron-shell effects. A rich\ndynamics involving movement and interaction of kinks connecting locally stable\nradii is found, and a new class of universal equilibrium shapes is predicted.",
        "positive": "Helicity-dependent Ultrafast Photocurrents in Weyl Magnet Mn$_3$Sn: We present an optical pump-THz emission study on non-collinear\nantiferromagnet Mn$_3$Sn. We show that Mn$_3$Sn acts as a source of THz\nradiation when irradiated by femtosecond laser pulses. The polarity and\namplitude of the emitted THz fields can be fully controlled by the polarisation\nof optical excitation. We explain the THz emission with the photocurrents\ngenerated via the photon drag effect by combining various experimental\nmeasurements as a function of pump polarisation, magnetic field, and sample\norientation with thorough symmetry analysis of response tensors."
    },
    {
        "anchor": "Moir\u00e9 Assisted Fractional Quantum Hall State Spectroscopy: Intra-Landau level excitations in the fractional quantum Hall regime are not\naccessible via optical absorption measurements. We point out that optical\nprobes are enabled by the periodic potentials produced by a moir\\'e pattern.\nOur observation is motivated by the recent observations of fractional quantum\nHall incompressible states in moir\\'e-patterned graphene on a hexagonal boron\nnitride substrate, and is theoretically based on $f-$sum rule considerations\nsupplemented by a perturbative analysis of the influence of the moir\\'e\npotential on many-body states.",
        "positive": "Effects of Quantum Tunneling in Metal Nano-gap on Surface-Enhanced Raman\n  Scattering: The quantum tunneling effects between two metallic plates are studied using\nthe time dependent density functional theory. Results show that the tunneling\nis mainly dependent on the separation and the initial local field of the\ninterstice between plates. The smaller separation and larger local field, the\neasier the electrons tunnels through the interstice. Our numerical calculation\nshows that when the separation is smaller than 0.6 nm the quantum tunneling\ndramatically reduce the enhancing ability of interstice between nanoparticles."
    },
    {
        "anchor": "Flat bands for electrons in rhombohedral graphene multilayers with a\n  twin boundary: Topologically protected flat surface bands make thin films of rhombohedral\ngraphite an appealing platform for searching for strongly correlated states of\n2D electrons. In this work, we study rhombohedral graphite with a twin boundary\nstacking fault and analyse the semimetallic and topological properties of\nlow-energy bands localised at the surfaces and at the twinned interface. We\nderive an effective 4-band low energy model, where we implement the full set of\nSlonczewski-Weiss-McClure (SWMcC) parameters, and find the conditions for the\nbands to be localised at the twin boundary, protected from the\nenvironment-induced disorder. This protection together with a high density of\nstates at the charge neutrality point, in some cases -- due to a Lifshitz\ntransition, makes this system a promising candidate for hosting\nstrongly-correlated effects.",
        "positive": "Plasmons in one and two dimensions: Plasmons in low-dimensional systems respresent an important tool for coupling\nenergy into nanostructures and the localization of energy on the scale of only\na few nanometers. Contrary to ordinary surface plasmons of metallic bulk\nmaterials, their dispersion goes to zero in the long wavelength limit, thus\ncovering a broad range of energies from terahertz to near infrared, and from\nmesoscopic wavelengths down to just a few nanometers. Using specific and most\ncharacteristic examples, we review first the properties of plasmons in\ntwo-dimensional (2D) metallic layers from an experimental point of view. As\ndemonstrated, tuning of their dispersion is possible by changes of charge\ncarrier concentration in the partially filled 2D conduction bands, but for the\nrelativistic electron gas like in graphene only in the long wavelength limit.\nFor short wavelengths, on the other hand, the dispersion turns out to be\nindependent of the position of the Fermi level with respect to the Dirac point.\nA linear dispersion, seen under the latter conditions in graphene, can also be\nobtained in non-relativistic electron gases by coupling between 2D and 3D\nelectronic systems. As a well investigated example, the acoustic surface\nplasmons in Shockley surface states, coupled with the bulk electronic system,\nare discussed. Also the introduction of anisotropy, e.g. by regular arrays of\nsteps, seems to result in linearization (and to partial localization of the\nplasmons normal to the steps, depending on wavelengths). In quasi-one\ndimensional (1D) systems, such as arrays of gold chains on regularly stepped Si\nsurfaces, only the dispersion is 1D, whereas shape and slope of the dispersion\ncurves depend on the 2D distribution of charge within each terrace and on\ncoupling between wires on different terraces."
    },
    {
        "anchor": "Non-local spin valve in Van der Pauw cross geometry with four\n  ferromagnetic electrodes: We consider a non-local spin valve in a Van der Pauw cross geometry with four\nferromagnetic electrodes. Two antiparallel ferromagnets are used as (charge)\nsource and drain while the detector circuit involves measuring the voltage\nbetween two collinear ferromagnets with parallel or antiparallel\nmagnetizations. We find a potentially large increase of the non-local spin\nvoltage. The setup displays several additional interesting properties: (i)\ninfinite GMR for the non-local resistance (if a symmetry requirement for the\ndevice is met); (ii) ON-OFF switch effect, when the injector electrodes are\nparallel instead of antiparallel; (iii) insensitivity to offset voltages. The\ndevice can additionally be used as a Direct Spin Hall Effect probe and as a\nreprogrammable magneto-logic gate implementing basic operations (NOR, NAND,\ninverter, AND, OR,...).",
        "positive": "Tunable Sample-wide Electronic Kagome Lattice in Low-angle Twisted\n  Bilayer Graphene: Overlaying two graphene layers with a small twist angle can create a moire\nsuperlattice to realize exotic phenomena that are entirely absent in graphene\nmonolayer. A representative example is the predicted formation of localized\npseudo-Landau levels (PLLs) with Kagome lattice in tiny-angle twisted bilayer\ngraphene (TBG) with theta < 0.3 deg when the graphene layers are subjected to\ndifferent electrostatic potentials. However, this was shown only for the model\nof rigidly rotated TBG which is not realized in reality due to an interfacial\nstructural reconstruction. It is believed that the interfacial structural\nreconstruction strongly inhibits the formation of the PLLs. Here, we\nsystematically study electronic properties of the TBG with 0.075 deg < theta <\n1.2 deg and demonstrate, unexpectedly, that the PLLs are quite robust for all\nthe studied TBG. The structural reconstruction suppresses the formation of the\nemergent Kagome lattice in the tiny-angle TBG. However, for the TBG around\nmagic angle, the sample-wide electronic Kagome lattices with tunable lattice\nconstants are directly imaged by using scanning tunneling microscope. Our\nobservations open a new direction to explore exotic correlated phases in moire\nsystems."
    },
    {
        "anchor": "Defect Engineering: Graphene Gets Designer Defects: An extended one-dimensional defect that has the potential to act as a\nconducting wire has been embedded in another perfect graphene sheet.",
        "positive": "Universal features of canonical phonon angular momentum without\n  time-reversal symmetry: It is known that phonons have angular momentum, and when the time-reversal\nsymmetry (TRS) is broken, the total phonon angular momentum in the whole system\nbecomes nonzero. In this paper, we propose that as an angular momentum of\nphonons for a crystal without TRS, we need to consider the canonical angular\nmomentum, as opposed to the kinetic angular momentum in previous works. Next,\nwe show that the angular momentum of phonons without TRS exhibits universal\nbehaviors near the $\\Gamma$ point. We focus on in-plane oscillations in\ntwo-dimensional crystals as an example. By breaking the TRS, one of the\nacoustic phonon branches at the $\\Gamma$ point acquires a gap. We show that the\nangular momentum of its acoustic phonon with a gap has a peak with the height\n$\\pm \\hbar$ regardless of the details of the system. From this, we find that\nthis peak height changes discontinuously by changing the sign of the\nTRS-breaking parameter."
    },
    {
        "anchor": "Laser-induced terahertz spin transport in magnetic nanostructures arises\n  from the same force as ultrafast demagnetization: Laser-induced terahertz spin transport (TST) and ultrafast demagnetization\n(UDM) are central but so far disconnected phenomena in femtomagnetism and\nterahertz spintronics. Here, we use broadband terahertz emission spectroscopy\nto reliably measure both processes in one setup. We find that the rate of UDM\nof a single ferromagnetic metal film F has the same time evolution as the flux\nof TST from F into an adjacent normal-metal layer N. This remarkable agreement\nshows that UDM and TST are driven by the same force, which is fully determined\nby the state of the ferromagnet. An analytical model consistently and\nquantitatively explains our observations. It reveals that both UDM in F and TST\nin the F|N stack arise from a generalized spin voltage, which is defined for\narbitrary, nonthermal electron distributions. We also conclude that\ncontributions due to a possible temperature difference between F and N are\nminor and that the spin-current amplitude can, in principle, be increased by\none order of magnitude. In general, our findings allow one to apply the vast\nknowledge of UDM to TST, thereby opening up new pathways toward large-amplitude\nterahertz spin currents and, thus, energy-efficient ultrafast spintronic\ndevices.",
        "positive": "Effect of strong correlation on the study of renormalization group flow\n  diagram for Kondo effect in a interacting quantum wire: We present the study of Kondo effect in an interacting quantum wire. We\nmainly emphasis the effect of strong electronic correlations in the study of\nrenormalization group flow diagram and the stability analysis of fixed points\nfor both magnetic and nonmagnetic impurities. We observe that the behavior of\nthe system is either in the single channel or in the two channel Kondo effect\ndepending on the initial values of coupling constants and strong correlations."
    },
    {
        "anchor": "Scaling Theory of ${\\mathbb Z}_{2}$ Topological Invariants: For inversion-symmetric topological insulators and superconductors\ncharacterized by ${\\mathbb Z}_{2}$ topological invariants, two scaling schemes\nare proposed to judge topological phase transitions driven by an energy\nparameter. The scaling schemes renormalize either the phase gradient or the\nsecond derivative of the Pfaffian of the time-reversal operator, through which\nthe renormalization group flow of the driving energy parameter can be obtained.\nThe Pfaffian near the time-reversal invariant momentum is revealed to display a\nuniversal critical behavior for a great variety of models examined.",
        "positive": "Electronic Glasses: A short introduction to the physics and the method to treat quantum crystals\nof electrons (Wigner crystal) and the related disordered elastic systems."
    },
    {
        "anchor": "Eigenstate switching of topologically ordered states using non-Hermitian\n  perturbations: Topologically ordered phases have robust degenerate ground states against the\nlocal perturbations, providing a promising platform for fault-tolerant quantum\ncomputation. Despite of the non-local feature of the topological order, we find\nthat local non-Hermitian perturbations can induce the transition between the\ntopologically ordered ground states. In this work, we study the toric code in\nthe presence of non-Hermitian perturbations. By controlling the\nnon-Hermiticity, we show that non-orthogonal ground states can exhibit an\neigenstate coalescence and have the spectral singularity, known as an\nexceptional point (EP). We explore the potential of the EPs in the control of\ntopological order. Adiabatic encircling EPs allows for the controlled switching\nof eigenstates, enabling dynamic manipulation between the ground state\ndegeneracy. Interestingly, we show a property of our scheme that arbitrary\nstrengths of local perturbations can induce the EP and eigenstate switching.\nFinally, we also show the orientation-dependent behavior of non-adiabatic\ntransitions (NAT) during the dynamic encirclement around an EP. Our work shows\nthat control of the non-Hermiticity can serve as a promising strategy for\nfault-tolerant quantum information processing.",
        "positive": "Graphene Side Gate Engineering: Various mesoscopic devices exploit electrostatic side gates for their\noperation. In this paper, we investigate how voltage-biasing of graphene side\ngates modulates the electrical transport characteristics of graphene channel.\nWe explore myriads of typical side gated devices such as symmetric dual side\ngates and asymmetric single side gate biasing, in monolayer and bilayer\ngraphene. The side gates modulate the electrostatic doping in the graphene\nchannel whose effect is reflected in transport measurement. This modulation\nefficiency is systematically characterized for all our devices and agrees well\nwith the modeling presented."
    },
    {
        "anchor": "Interference Effects on Kondo-Assisted Transport through Double Quantum\n  Dots: We systematically investigate electron transport through double quantum dots\nwith particular emphasis on interference induced via multiple paths of electron\npropagation. By means of the slave-boson mean-field approximation, we calculate\nthe conductance, the local density of states, the transmission probability in\nthe Kondo regime at zero temperature. It is clarified how the Kondo-assisted\ntransport changes its properties when the system is continuously changed among\nthe serial, parallel and T-shaped double dots. The obtained results for the\nconductance are explained in terms of the Kondo resonances influenced by\ninterference effects. We also discuss the impacts due to the spin-polarization\nof ferromagnetic leads.",
        "positive": "Zitterbewegung of a heavy hole in presence of spin-orbit interactions: We study the $zitterbewegung$ of a heavy hole in presence of both cubic\nRashba and cubic Dresselhaus spin-orbit interactions. On contrary to the\nelectronic case, $zitterbewegung$ does not vanish for equal strength of Rashba\nand Dresselhaus spin-orbit interaction. This non-vanishing of $zitterbewegung$\nis associated with the Berry phase. Due to the presence of the spin-orbit\ncoupling the spin associated with the heavy hole precesses about an effective\nmagnetic field. This spin precession produces a transverse spin-orbit force\nwhich also generates an electric voltage associated with $zitterbewegung$. We\nhave estimated the magnitude of this voltage for a possible experimental\ndetection of $zitterbewegung$."
    },
    {
        "anchor": "Graphene-protein bioelectronic devices with wavelength-dependent\n  photoresponse: We implemented a nanoelectronic interface between graphene field effect\ntransistors (FETs) and soluble proteins. This enables production of\nbioelectronic devices that combine functionalities of the biomolecular and\ninorganic components. The method serves to link polyhistidine-tagged proteins\nto graphene FETs using the tag itself. Atomic Force Microscopy and Raman\nspectroscopy provide structural understanding of the bio/nano hybrid;\ncurrent-gate voltage measurements are used to elucidate the electronic\nproperties. As an example application, we functionalize graphene FETs with\nfluorescent proteins to yield hybrids that respond to light at wavelengths\ndefined by the optical absorption spectrum of the protein",
        "positive": "On the Implications of Discrete Symmetries for the Beta Function of\n  Quantum Hall Systems: We argue that the large discrete symmetry group of quantum Hall systems is\ninsufficient in itself to determine the complete beta function for the scaling\nof the conductivities, $\\sigma_{xx}$ and $\\sigma_{xy}$. We illustrate this\npoint by showing that a recent ansatz for this function is one of a\nmany-parameter family. A clean prediction for the delocalization exponents for\nthese systems therefore requires the specification of more information, such as\npast proposals that the beta function is either holomorphic or\nquasi-holomorphic in the variable $z = (\\hbar/e^2)(\\sigma_{xy} +\ni\\sigma_{xx})$."
    },
    {
        "anchor": "Lasing and antibunching of optical phonons in semiconductor double\n  quantum dots: We theoretically propose optical phonon lasing in a double quantum dot (DQD)\nfabricated on a semiconductor substrate. No additional cavity or resonator is\nrequired. An electron in the DQD is found to be coupled to only two\nlongitudinal optical phonon modes that act as a natural cavity. When the energy\nlevel spacing in the DQD is tuned to the phonon energy, the electron transfer\nis accompanied by the emission of the phonon modes. The resulting\nnon-equilibrium motion of electrons and phonons is analyzed by the rate\nequation approach based on the Born-Markov-Secular approximation. We show that\nthe lasing occurs for pumping the DQD via electron tunneling at rate much\nlarger than the phonon decay rate, whereas a phonon antibunching is observed in\nthe opposite regime of slow tunneling. Both effects disappear by an effective\nthermalization induced by the Franck-Condon effect in a DQD fabricated in a\nsuspended carbon nanotube with strong electron-phonon coupling.",
        "positive": "Nuclear spin readout in a cavity-coupled hybrid quantum dot-donor system: Nuclear spins show long coherence times and are well isolated from the\nenvironment, which are properties making them promising for quantum information\napplications. Here, we present a method for nuclear spin readout by probing the\ntransmission of a microwave resonator. We consider a single electron in a\nsilicon quantum dot-donor device interacting with a microwave resonator via the\nelectric dipole coupling and subjected to a homogeneous magnetic field and a\ntransverse magnetic field gradient. In our scenario, the electron spin\ninteracts with a $^{31}\\mathrm{P}$ defect nuclear spin via the hyperfine\ninteraction. We theoretically investigate the influence of the P nuclear spin\nstate on the microwave transmission through the cavity and show that nuclear\nspin readout is feasible with current state-of-the-art devices. Moreover, we\nidentify optimal readout points with strong signal contrast to facilitate the\nexperimental implementation of nuclear spin readout. Furthermore, we\ninvestigate the potential for achieving coherent excitation exchange between a\nnuclear spin qubit and cavity photons."
    },
    {
        "anchor": "Dynamical Majorana Ising spin response in a topological\n  superconductor-magnet hybrid by microwave irradiation: We study a dynamical spin response of surface Majorana modes in a topological\nsuperconductor-magnet hybrid under microwave irradiation. We find a method to\ntoggle between dissipative and non-dissipative Majorana Ising spin dynamics by\nadjusting the external magnetic field angle and the microwave frequency. This\nreflects the topological nature of the Majorana modes, enhancing the Gilbert\ndamping of the magnet, thereby, providing a detection method for the Majorana\nIsing spins. Our findings illuminate a magnetic probe for Majorana modes,\npaving the path to innovative spin devices.",
        "positive": "Strong Enhancement of Rashba spin-orbit coupling with increasing\n  anisotropy in the Fock-Darwin states of a quantum dot: We have investigated the electronic properties of elliptical quantum dots in\na perpendicular external magnetic field, and in the presence of the Rashba\nspin-orbit interaction. Our work indicates that the Fock-Darwin spectra display\nstrong signature of Rashba spin-orbit coupling even for a low magnetic field,\nas the anisotropy of the quantum dot is increased. An explanation of this\npronounced effect with respect to the anisotropy is presented. The strong\nspin-orbit coupling effect manifests itself prominently in the corresponding\ndipole-allowed optical transitions, and hence is susceptible to direct\nexperimental observation."
    },
    {
        "anchor": "Evidence of heavy fermion physics in the thermoelectric transport of\n  magic angle twisted bilayer graphene: It has been recently postulated, that the strongly correlated flat bands of\nmagicangle twisted bilayer graphene (MATBG) can host coexisting heavy and light\ncarriers. While transport and spectroscopic measurements have shown hints of\nthis behavior, a more direct experimental proof is still lacking. Here, we\nexplore the thermoelectric response of MATBG through the photo-thermoelectric\n(PTE) effect in gate-defined MATBG pn-junctions. At low temperatures, we\nobserve sign-preserving, fillingdependent oscillations of the Seebeck\ncoefficient at non-zero integer fillings of the moir\\'e lattice, which suggest\nthe preponderance of one carrier type despite tuning the Fermi level from hole\nto electron doping of the correlated insulator. Furthermore, at higher\ntemperatures, the thermoelectric response provides distinct evidence of the\nstrong electron correlations in the unordered, normal state. We show that our\nobservations are naturally accounted for by the interplay of light and\nlong-lived and heavy and short-lived electron bands near the Fermi level at\nnon-zero integer fillings. Our observations firmly establish the electron and\nhole asymmetry of the correlated gaps in MATBG, and shows excellent qualitative\nagreement with the recently developed topological heavy fermion model (THF).",
        "positive": "Gate-controlled nuclear magnetic resonance in an AlGaAs/GaAs quantum\n  Hall device: We study the resistively detected nuclear magnetic resonance (NMR) in an\nAlGaAs/GaAs quantum Hall device with a side gate. The strength of the hyperfine\ninteraction between electron and nuclear spins is modulated by tuning a\nposition of the two-dimensional electron systems with respect to the polarized\nnuclear spins using the side-gate voltages. The NMR frequency is systematically\ncontrolled by the gate-tuned technique in a semiconductor device."
    },
    {
        "anchor": "Optical properties of current carrying molecular wires: We consider several fundamental optical phenomena involving single molecules\nin biased metal-molecule-metal junctions. The molecule is represented by its\nhighest occupied and lowest unoccupied molecular orbitals, and the analysis\ninvolves the simultaneous consideration of three coupled fluxes: the electronic\ncurrent through the molecule, energy flow between the molecule and\nelectron-hole excitations in the leads and the incident and/or emitted photon\nflux. Using a unified theoretical approach based on the non-equilibrium Green\nfunction method we derive expressions for the absorption lineshape (not an\nobservable but a ueful reference for considering yields of other optical\nprocesses) and for the current induced molecular emission in such junctions. We\nalso consider conditions under which resonance radiation can induce electronic\ncurrent in an unbiased junction. We find that current driven molecular emission\nand resonant light induced electronic currents in single molecule junctions can\nbe of observable magnitude under appropriate realizable conditions. In\nparticular, light induced current should be observed in junctions involving\nmolecular bridges that are characterized by strong charge transfer optical\ntransitions. For observing current induced molecular emission we find that in\naddition to the familiar need to control the damping of molecular excitations\ninto the metal substrate the phenomenon is also sensitive to the way in which\nthe potential bias si distributed on the junction.",
        "positive": "On derivation of Dresselhaus spin-splitting Hamiltonians in\n  one-dimensional electron systems: Two-dimensional (2D) semiconductor structures of materials without inversion\ncenter (e.g. zinc-blende ${\\rm A^{III}B^V}$) possess the zero-field conduction\nband spin-splitting (Dresselhaus term), which is linear and cubic in wavevector\n$k$, that arises from cubic in $k$ splitting in a bulk material. At low carrier\nconcentration the cubic term is usually negligible. However, if we will be\ninterested in the following dimensional quantization (in 2D plane) and the\ncharacter width in this direction is comparable with the width of 2D-structure,\nthen we have to take into account $k^3$-terms as well (even at low\nconcentrations), that after quantization leads to comparable contribution that\narises from $k$-linear term. We propose the general procedure for derivation of\nDresselhaus spin-splitting Hamiltonian applicable for any curvilinear\n1D-structures. The simple examples for the cases of a quantum wire (QWr) and a\nquantum ring (QR) defined in usual [001]-grown 2D-structure are presented."
    },
    {
        "anchor": "Attraction of indirect excitons in van der Waals heterostructures with\n  three semiconducting layers: We study a capacitor made of three monolayers of transition metal\ndichalcogenide (TMD) separated by hexagonal Boron Nitride (hBN). We assume that\nthe structure is symmetric with respect to the central layer plane. The\nsymmetry includes the contacts: if the central layer is contacted by the\nnegative electrode, both external layers are contacted by the positive one. As\na result a strong enough voltage $V$ induces electron-hole dipoles (indirect\nexcitons) pointing towards one of the external layers. Antiparallel dipoles\nattract each other at large distances. Thus, the dipoles alternate in the\ncentral plane forming a 2D antiferroelectric with negative binding energy per\ndipole. The charging of a three-layer device is a first order transition, and\nwe show that if $V_1$ is the critical voltage required to create a single\nelectron-hole pair and charge this capacitor by $e$, the macroscopic charge\n$Q_c = eSn_c$ ($S$ is the device area) enters the three-layer capacitor at a\nsmaller critical voltage $V_{c} < V_{1}$. In other words, the differential\ncapacitance $C(V)$ is infinite at $V = V_{c}$. We also show that in a\ncontact-less three-layer device, where the chemically different central layer\nhas lower conduction and valence bands, optical excitation creates indirect\nexcitons which attract each other, and therefore form antiferroelectric exciton\ndroplets. Thus, the indirect exciton luminescence is red shifted compared to a\ntwo-layer device.",
        "positive": "Dyakonov-Shur instability of electronic fluid: Spectral effect of weak\n  magnetic field: We study numerically and analytically how the Dyakonov-Shur instability for a\ntwo-dimensional (2D) inviscid electronic fluid in a long channel can be\naffected by an external, out-of-plane static magnetic field. By linear\nstability analysis for a model based on the shallow-water equations, we\ndescribe the discrete spectrum of frequencies in the complex plane. When the\nfluid system is near the subsonic-to-supersonic transition point, a\nmagnetically controlled gap between the stability and instability spectra of\nthe complex eigen-frequencies is evident by our computations. This suggests\nthat the passage from stability to instability (and vice versa) is no longer\ncontinuous in the effective Mach parameter of the boundary conditions. We\nconnect this complex-valued gap to a multivalued function characterizing the\nexact electronic steady state. In a regime of weak magnetic fields, we derive a\nscaling law for the eigen-frequencies by perturbation theory. We discuss\nimplications of our results in efforts to generate terahertz electromagnetic\nradiation by 2D electronic transport."
    },
    {
        "anchor": "Electronic heat tunneling between two metals beyond the WKB\n  approximation: Two metals at different temperatures separated by large gaps exchange heat\nunder the form of electromagnetic radiation. When the separation distance is\nreduced and they approach contact (nanometer and sub-nanometer gaps), electrons\nand phonons can tunnel between the bodies, competing and eventually going\nbeyond the flux mediated by thermal photons. In this transition regime the\naccurate modeling of electronic current and heat flux is of major importance.\nHere we show that, in order to quantitatively model this transfer, a careful\ndescription of the tunneling barrier between two metals is needed and going\nbeyond the traditional WKB approximation is also essential. We employ\nanalytical and numerical approaches to model the electronic potential between\ntwo semi-infinite jellium planar substrates separated by a vacuum gap in order\nto calculate the electronic heat flow and compare it with its radiative\ncounterpart described by near-field radiative heat transfer. We demonstrate\nthat the results for heat flux and electronic current density are extremely\nsensitive to both the shape and height of the barrier, as well as the\ncalculation scheme for the tunneling probability, with variations up to several\norders of magnitude. Using the proximity force approximation, we also provide\nestimates for tip-plane geometries. The present work provides realistic models\nto describe the electronic heat flux, in the scanning-thermal-microscopy\nexperiments.",
        "positive": "Magnonic crystals for data processing: Magnons - the quanta of spin waves - propagating in magnetic materials with\nwavelengths at the nanometer-scale and carrying information in the form of an\nangular momentum, can be used as data carriers in next-generation, nano-sized\nlow-loss information processing systems. In this respect, artificial magnetic\nmaterials with properties periodically varied in space, known as magnonic\ncrystals, are especially promising for controlling and manipulating the magnon\ncurrents. In this article, different approaches for the realization of static,\nreconfigurable, and dynamic magnonic crystals are presented along with a\nvariety of novel wave phenomena discovered in these crystals. Special attention\nis devoted to the utilization of magnonic crystals for processing of analog and\ndigital information."
    },
    {
        "anchor": "The quest and hope of Majorana zero modes in topological superconductor\n  for fault-tolerant quantum computing: an introductory overview: Ettore Majorana, in his short life, unintendedly has uncovered the most\nprofound problem in quantum computation by his discovery of Majorana fermion, a\nparticle which is its own anti-particle. Owing to its non-Abelian exchange\nstatistics, Majorana fermions may act as a qubit for a universal quantum\ncomputer which is fault-tolerant. The existence of such particle is predicted\nin mid-gap states (zero modes) of a topological superconductor as bound states\nthat have a highly entangled degenerate ground state. This introductory\noverview will focus on the simplest theoretical proposals of Majorana fermions\nfor topological quantum computing in superconducting systems, emphasizing the\nquest from the scalability problem of quantum computer to its possible solution\nwith topological quantum computer employing non-Abelian anyons on various\nplatforms of certain Majorana fermion signature encountered.",
        "positive": "Energy gap tuning and gate-controlled topological phase transition in\n  InAs/In$_{x}$Ga$_{1-x}$Sb composite quantum wells: We report transport measurements of strained InAs/In$_{x}$Ga$_{1-x}$Sb\ncomposite quantum wells (CQWs) in the quantum spin Hall phase, focusing on the\ncontrol of the energy gap through structural parameters and an external\nelectric field. For highly strained CQWs with $x = 0.4$, we obtain a gap of 35\nmeV, an order of magnitude larger than that reported for binary InAs/GaSb CQWs.\nUsing a dual-gate configuration, we demonstrate an electrical-field-driven\ntopological phase transition, which manifests itself as a re-entrant behavior\nof the energy gap. The sizeable energy gap and high bulk resistivity obtained\nin both the topological and normal phases of a single device open the\npossibility of electrical switching of the edge transport."
    },
    {
        "anchor": "Breaking down the magnonic Wiedemann-Franz law in the hydrodynamic\n  regime: Recent experiments have shown an indication of a hydrodynamic magnon behavior\nin ultrapure ferromagnetic insulators; however, its direct observation is still\nlacking. Here, we derive a set of coupled hydrodynamic equations and study the\nthermal and spin conductivities for such a magnon fluid. We reveal the drastic\nbreakdown of the magnonic Wiedemann-Franz law as a hallmark of the\nhydrodynamics regime, which will become key evidence for the experimental\nrealization of an emergent hydrodynamic magnon behavior. Therefore, our results\npave the way towards the direct observation of magnon fluids.",
        "positive": "Magnon hybridization in ferrimagnetic heterostructures: We study magnon hybridization in a ferrimagnetic heterostructure consisting\nof ultrathin gadolinium iron garnet and yttrium iron garnet layers and show the\nlocalized and extended spatial profiles of the magnon modes with different\npolarizations. These modes are expected to have distinct thermal excitation\nproperties in the presence of a temperature gradient across the\nheterostructure. From a quantitative analysis of their consequences on\nlongitudinal spin Seebeck effect, we predict an observable shift of the\nsign-changing temperature with respect to the one previously observed in\ngadolinium iron garnet. Moreover, the sign-changing point of spin Seebeck\nsignal is found to be tunable by YIG thickness. Our results suggest the\nnecessity of taking into account the temperature difference between the magnon\nmodes in ferrimagnetic heterostructures."
    },
    {
        "anchor": "Anisotropic Spin-Acoustic Resonance in Silicon Carbide at Room\n  Temperature: We report on acoustically driven spin resonances in atomic-scale centers in\nsilicon carbide at room temperature. Specifically, we use a surface acoustic\nwave cavity to selectively address spin transitions with magnetic quantum\nnumber differences of $\\pm$1 and $\\pm$2 in the absence of external microwave\nelectromagnetic fields. These spin-acoustic resonances reveal a non-trivial\ndependence on the static magnetic field orientation, which is attributed to the\nintrinsic symmetry of the acoustic fields combined with the peculiar properties\nof a half-integer spin system. We develop a microscopic model of the\nspin-acoustic interaction, which describes our experimental data without\nfitting parameters. Furthermore, we predict that traveling surface waves lead\nto a chiral spin-acoustic resonance, which changes upon magnetic field\ninversion. These results establish silicon carbide as a highly-promising hybrid\nplatform for on-chip spin-optomechanical quantum control enabling engineered\ninteractions at room temperature.",
        "positive": "Magic number theory of superconducting proximity effects and Wigner\n  delay times in graphene-like molecules: When a single molecule is connected to external electrodes by linker groups,\nthe connectivity of the linkers to the molecular core can be controlled to\natomic precision by appropriate chemical synthesis. Recently, the connectivity\ndependence of the electrical conductance and Seebeck coefficient of single\nmolecules has been investigated both theoretically and experimentally. Here we\nstudy the connectivity dependence of the Wigner delay time of single-molecule\njunctions and the connectivity dependence of superconducting proximity effects,\nwhich occur when the external electrodes are replaced by superconductors.\nAlthough absolute values of transport properties depend on complex and often\nuncontrolled details of the coupling between the molecule and electrodes, we\ndemonstrate that ratios of transport properties can be predicted using tables\nof 'magic numbers,' which capture the connectivity dependence of\nsuperconducting proximity effects and Wigner delay times within molecules.\nThese numbers are calculated easily, without the need for large-scale\ncomputations. For normal-molecule-superconducting junctions, we find that the\nelectrical conductance is proportional to the fourth power of their magic\nnumbers, whereas for superconducting-molecule-superconducting junctions, the\ncritical current is proportional to the square of their magic numbers. For more\nconventional normal-molecule-normal junctions, we demonstrate that delay time\nratios can be obtained from products of magic number tables."
    },
    {
        "anchor": "Thermal States of Anyonic Systems: A study of the thermal properties of two-dimensional topological lattice\nmodels is presented. This work is relevant to assess the usefulness of these\nsystems as a quantum memory. For our purposes, we use the topological mutual\ninformation $I_{\\mathrm{topo}}$ as a \"topological order parameter\". For Abelian\nmodels, we show how $I_{\\mathrm{topo}}$ depends on the thermal topological\ncharge probability distribution. More generally, we present a conjecture that\n$I_{\\mathrm{topo}}$ can (asymptotically) be written as a Kullback-Leitner\ndistance between this probability distribution and that induced by the quantum\ndimensions of the model at hand. We also explain why $I_{\\mathrm{topo}}$ is\nmore suitable for our purposes than the more familiar entanglement entropy\n$S_{\\mathrm{topo}}$. A scaling law, encoding the interplay of volume and\ntemperature effects, as well as different limit procedures, are derived in\ndetail. A non-Abelian model is next analysed and similar results are found.\nFinally, we also consider, in the case of a one-plaquette toric code, an\nenvironment model giving rise to a simulation of thermal effects in time.",
        "positive": "Anomalous flux periodicity in proximitised quantum spin Hall\n  constrictions: We theoretically analyse a long constriction between the helical edge states\nof a two-dimensional topological insulator. The constriction is laterally\ntunnel-coupled to two superconductors and a magnetic field is applied\nperpendicularly to the plane of the two-dimensional topological insulator. The\nJosephson current is calculated analytically up to second order in the tunnel\ncoupling both in the absence and in the presence of a bias (DC and AC Josephson\ncurrents). We show that in both cases the current acquires an anomalous\n$4\\pi$-periodicity with respect to the magnetic flux that is absent if the two\nedges are not tunnel-coupled to each other. The result, that provides at the\nsame time a characterisation of the device and a possible experimental\nsignature of the coupling between the edges, is stable against temperature. The\nprocesses responsible for the anomalous $4\\pi$-periodicity are the ones where,\nwithin the constriction, one of the two electrons forming a Cooper pair tunnels\nbetween the two edges."
    },
    {
        "anchor": "High density limit of the two-dimensional electron liquid with Rashba\n  spin-orbit coupling: We discuss by analytic means the theory of the high-density limit of the\nunpolarized two-dimensional electron liquid in the presence of Rashba or\nDresselhaus spin-orbit coupling. A generalization of the ring-diagram expansion\nis performed. We find that in this regime the spin-orbit coupling leads to\nsmall changes of the exchange and correlation energy contributions, while\nmodifying also, via repopulation of the momentum states, the noninteracting\nenergy. As a result, the leading corrections to the chirality and total energy\nof the system stem from the Hartree-Fock contributions. The final results are\nfound to be vanishing to lowest order in the spin-orbit coupling, in agreement\nwith a general property valid to every order in the electron-electron\ninteraction. We also show that recent quantum Monte Carlo data in the presence\nof Rashba spin-orbit coupling are well understood by neglecting corrections to\nthe exchange-correlation energy, even at low density values.",
        "positive": "Thermal rectification through the topological states of asymmetrical\n  length armchair graphene nanoribbons heterostructures with vacancies: We present a theoretical investigation of electron heat current in\nasymmetrical length armchair graphene nanoribbon (AGNR) heterostructures with\nvacancies, focusing on the topological states (TSs). In particular, we examine\nthe 9-7-9 AGNR heterostructures where the TSs are well-isolated from the\nconduction and valence subbands. This isolation effectively mitigates thermal\nnoise of subbands arising from temperature fluctuations during charge\ntransport. Moreover, when the TSs exhibit an orbital off-set, intriguing\nelectron heat rectification phenomena are observed, primarily attributed to\ninter-TS electron Coulomb interactions. To enhance the heat rectification ratio\n($\\eta_Q$), we manipulate the coupling strengths between the heat sources and\nthe TSs by introducing asymmetrical lengths in the 9-AGNRs. This approach\noffers control over the rectification properties, enabling significant\nenhancements. Additionally, we introduce vacancies strategically positioned\nbetween the heat sources and the TSs to suppress phonon heat current. This\narrangement effectively reduces the overall phonon heat current, while leaving\nthe TSs unaffected. Our findings provide valuable insights into the behavior of\nelectron heat current in AGNR heterostructures, highlighting the role of\ntopological states, inter-TS electron Coulomb interactions, and the impact of\nstructural modifications such as asymmetrical lengths and vacancy positioning.\nThese results pave the way for the design and optimization of graphene-based\ndevices with improved thermal management and efficient control of electron heat\ntransport."
    },
    {
        "anchor": "Spin Entanglement in supramolecular structures: Molecular spin clusters are mesoscopic systems whose structural and physical\nfeatures can be tailored at the synthetic level. Besides, their quantum\nbehavior is directly accessible in laboratory and their magnetic properties can\nbe rationalized in terms of microscopic spin models. Thus they represent an\nideal playground within solid state systems to test concepts in quantum\nmechanics. One intriguing challenge is to control entanglement between\nmolecular spins. Here we show how this goal can be pursued by discussing\nspecific examples and referring to recent achievements.",
        "positive": "Magnetotransport study of the mini-Dirac cone in AB-stacked four- to\n  six-layer graphene under perpendicular electric field: Landau levels of AB-stacked four- to six-layer graphene were studied\nexperimentally in the presence of a perpendicular electric field. The Landau\nlevels at a low magnetic field showed a characteristic structure that\noriginated from the mini-Dirac cones created by the perpendicular electric\nfields. Six-fold or twelve-fold degenerate Landau levels arising from the\nmini-Dirac cones were observed in the vicinity of the charge neutrality point\nas a radial structure in a plot of their Landau fan diagrams. The structure of\nfour-layer graphene had approximate electron-hole symmetry near the charge\nneutrality point, while the five- and six-layer graphene showed asymmetry.\nNumerical calculations of the dispersion relation and Landau level spectra\nindicated that trigonal warping played an essential role in forming the\nexperimentally observed Landau level structure in low magnetic fields. In high\nmagnetic fields, trigonal warping becomes less significant and the Landau level\nspectra become simpler, approaching those that were calculated without\nconsidering trigonal warping. The appearance of mini-Dirac cones in a\nperpendicular electric field would be a common feature of AB-stacked multilayer\ngraphene."
    },
    {
        "anchor": "Edge states and the bulk-boundary correspondence in Dirac Hamiltonians: We present an analytic prescription for computing the edge dispersion E(k) of\na tight-binding Dirac Hamiltonian terminated at an abrupt crystalline edge.\nSpecifically, we consider translationally invariant Dirac Hamiltonians with\nnearest-layer interaction. We present and prove a geometric formula that\nrelates the existence of surface states as well as their energy dispersion to\nproperties of the bulk Hamiltonian. We further prove the bulk-boundary\ncorrespondence between the Chern number and the chiral edge modes for quantum\nHall systems within the class of Hamiltonians studied in the paper. Our results\ncan be extended to the case of continuum theories which are quadratic in the\nmomentum, as well as other symmetry classes.",
        "positive": "Coulomb-interaction induced incomplete shell filling in the hole system\n  of InAs quantum dots: We have studied the hole charging spectra of self-assembled InAs quantum dots\nin perpendicular magnetic fields by capacitance-voltage spectroscopy. From the\nmagnetic field dependence of the individual peaks we conclude that the s-like\nground state is completely filled with two holes but that the fourfold\ndegenerate p-shell is only half filled with two holes before the filling of the\nd-shell starts. The resulting six-hole ground state is highly polarized. This\nincomplete shell filling can be explained by the large influence of the Coulomb\ninteraction in this system."
    },
    {
        "anchor": "Two-dimensional GaAs/AlGaAs superlattice structures for solar cell\n  applications: ultimate efficiency estimation: We calculate the band structure of a two-dimensional GaAs/AlGaAs superlattice\nand estimate the ultimate efficiency of solar cells using this type of\nstructure for solar energy conversion. The superlattice under consideration\nconsists of gallium arsenide rods forming a square lattice and embedded in\naluminium gallium arsenide. The ultimate efficiency is determined versus\nstructural parameters including the filling fraction, the superlattice\nconstant, the rod geometry and the concentration of Al in the matrix material.\nThe calculated efficiency of the superlattice proves to exceed the efficiency\nof each component material in the monolithic state in a wide range of parameter\nvalues.",
        "positive": "Floquet engineering the Hofstadter butterfly in the square lattice and\n  its effective Hamiltonian: In this paper, we use Floquet theory to theoretically study the effect of\nmonochromatic circularly and linearly polarized light on the Hofstadter\nbutterfly in the square lattice, which is induced by uniform perpendicular\nmagnetic field. In the absence of laser, the butterfly has a fractal,\nself-similar structure particle-hole symmetry and reflection symmetry about\nmagnetic flux $\\phi = 1/2$. These symmetries are preserved by the sub-lattice\nand the time-reversal symmetry, respectively. As the system is exposed to\ncircularly polarized light, the original Hofsatdter butterfly in equilibrium is\ndeformed by breaking both the particle-hole symmetry and the mirror symmetry,\nwhile the inversion symmetry about energy $E=0$ and magnetic flux $\\phi=1/2$ is\npreserved. Our study show that, the circularly polarized light break both the\nsub-lattice symmetry and the time-reversal symmetry. The inversion symmetry is\npreserved because the Hamiltonian at magnetic flux $\\phi$ and $1-\\phi$ is\nconnected through the sub-lattice transformation. Focusing on the small flux\nregion, we study the Landau level and the influence of circularly polarized\nlight on the Landau level. On the contrary, the linearly polarized light\ndeforms the original Hofstadter butterfly by breaking the rotational symmetry\nwhile preserving sub-lattice and the time-reversal symmetry. Further, we study\nthe influence of the periodic drive on the Chern number of the lowest band in\nmiddle Floquet copy within the off-resonance regime. We found strong circularly\npolarized light will change the Chern number. For linearly polarized light, the\nChern number will not change and the values stay independent of laser\npolarization direction. Our work highlights the generic features expected for\nthe periodically driven Hofstadter problem on square lattice and provide the\nstrategy to engineering the Hofstadter butterfly with laser."
    },
    {
        "anchor": "Filtering Spins by Scattering from a Lattice of Point Magnets: Nature creates electrons with two values of the spin projection quantum\nnumber. In certain applications, it is important to filter electrons with one\nspin projection from the rest. Such filtering is not trivial, since\nspin-dependent interactions are often weak, and cannot lead to any substantial\neffect. Here we propose an efficient spin filter based upon scattering from a\ntwo-dimensional crystal, which is made of aligned point magnets. The\npolarization of the outgoing electron flux is controlled by the crystal, and\nreaches maximum at specific values of the parameters. In our scheme,\npolarization increase is accompanied by higher reflectivity of the crystal.\nHigh transmission is feasible in scattering from a quantum cavity made of two\ncrystals. Our findings can be used for studies of low-energy spin-dependent\nscattering from two-dimensional ordered structures made of magnetic atoms or\naligned chiral molecules.",
        "positive": "Non-Abelian Fibonacci quantum Hall states in 4-layer rhombohedral\n  stacked graphene: It is known that $n$-degenerate Landau levels with the same spin-valley\nquantum number can be realized by $n$-layer graphene with rhombohedral stacking\nunder magnetic field $B$. We find that the wave functions of degenerate Landau\nlevels are concentrated at the surface layers of the multi-layer graphene if\nthe dimensionless ratio $\\eta = \\gamma_1/(v_F\\sqrt{2e\\hbar B/c}) \\approx\n9/\\sqrt{B[\\text{Tesla}]} \\gg 1$, where $\\gamma_1$ is the interlayer hopping\nenergy and $v_F$ the Fermi velocity of single-layer graphene. This allows us to\nsuggest that: 1) filling fraction $\\nu=\\frac12$ (or $\\nu_n = 5\\frac12$)\nnon-Abelian state with Ising anyon can be realized in three-layer graphene for\nmagnetic field $ B \\in [ 2 , 9] $ Tesla; 2) filling fraction $\\nu=\\frac23$ (or\n$\\nu_n = 7\\frac13$) non-Abelian state with Fibonacci anyon can be realized in\nfour-layer graphene for magnetic field $ B \\in [ 5 , 9] $ Tesla. Here, $\\nu$ is\nthe total filling fraction in the degenerate Landau levels, and $\\nu_n$ is the\nfilling fraction measured from charge neutrality point which determines the\nmeasured Hall conductance. We have assumed the following conditions to obtain\nthe above results: the exchange effect of Coulomb interaction polarizes the\n$SU(4)$ spin-valley quantum number in the degenerate Landau levels and\neffective dielectric constant $\\epsilon \\gtrsim 10$ to reduce the Coulomb\ninteraction. The high density of states of multi-layer graphene helps to reduce\nthe Coulomb interaction via screening."
    },
    {
        "anchor": "Geometric properties of adiabatic quantum thermal machines: We present a general unified approach for the study of quantum thermal\nmachines, including both heat engines and refrigerators, operating under\nperiodic adiabatic driving and in contact with thermal reservoirs kept at\ndifferent temperatures. We show that many observables characterizing this\noperating mode and the performance of the machine are of geometric nature.\nHeat-work conversion mechanisms and dissipation of energy can be described,\nrespectively, by the antisymmetric and symmetric components of a thermal\ngeometric tensor defined in the space of time-dependent parameters generalized\nto include the temperature bias. The antisymmetric component can be identified\nas a Berry curvature, while the symmetric component defines the metric of the\nmanifold. We show that the operation of adiabatic thermal machines, and\nconsequently also their efficiency, are intimately related to these geometric\naspects. We illustrate these ideas by discussing two specific cases: a slowly\ndriven qubit asymmetrically coupled to two bosonic reservoirs kept at different\ntemperatures, and a quantum dot driven by a rotating magnetic field and\nstrongly coupled to electron reservoirs with different polarizations. Both\nexamples are already amenable for an experimental verification.",
        "positive": "Enhanced Spin Dependent Shot Noise in Magnetic Tunnel Barriers: We report the observation of enhanced spin dependent shot noise in magnetic\ntunnel barriers, suggesting transport through localized states within the\nbarrier. This is supported by the existence of negative magnetoresistance and\nstructure in the differential conductance curves. A simple model of tunneling\nthrough two interacting localized states with spin dependent tunneling rates is\nused to explain our observations."
    },
    {
        "anchor": "Power spectrum of electronic heat current fluctuations: We analyze the fluctuations of an electronic thermal current across an\nidealized molecular junction. The focus here will be on the spectral features\nof the resulting heat fluctuations. By use of the Green functionmethod we\nderive an explicit expression for the frequency-dependent power spectral\ndensity of the emerging energy fluctuations. The complex expression simplifies\nconsiderably in the limit of zero frequency, yielding the noise intensity of\nthe heat current. The spectral density for the electronic heat fluctuations\nstill depends on the frequency in the zero-temperature limit, assuming\ndifferent asymptotic behaviours in the low- and high-frequency regions. We\nfurther address subtleties and open problems from an experimental viewpoint for\nmeasurements of frequency-dependent power spectral densities.",
        "positive": "Photoluminescence and transport in selectively doped p-GaAs/AlGaAs\n  quantum wells: manifestation of the upper Hubbard band: By selective doping (Be) of the well and barrier regions of p-GaAs/AlGaAs\nstructures we have realized the situation where the upper Hubbard band (A+\ncenters) has been occupied by holes in the equilibrium. We studied temperature\nbehavior of the Hall effect, variable range hopping conductivity and the\nphotoluminescence spectra of the corresponding structures. The experimental\ndata demonstrated that the binding energy of the A+ states significantly\nincreases with respect to 3D case and strongly depends on well width\n(9nm,15nm). The localization radii of the A+ states are of the order of well\nwidths."
    },
    {
        "anchor": "The Role of Electrical and Thermal Contact Resistance for Joule\n  Breakdown of Single-Wall Carbon Nanotubes: Several data sets of electrical breakdown in air of single-wall carbon\nnanotubes (SWNTs) on insulating substrates are collected and analyzed. A\nuniversal scaling of the Joule breakdown power with nanotube length is found,\nwhich appears independent of the insulating substrates used or their thickness.\nThis suggests the thermal resistances at the interface between SWNT and\ninsulator, and between SWNT and electrodes, govern heat sinking from the\nnanotube. Analytical models for the breakdown power scaling are presented,\nproviding an intuitive, physical understanding of the breakdown process. The\nelectrical and thermal resistance at the electrode contacts limit the breakdown\nbehavior for sub-micron SWNTs, the breakdown power scales linearly with length\nfor microns-long tubes, and a minimum breakdown power (~ 0.05 uW) is observed\nfor the intermediate (~ 0.5 um) length range.",
        "positive": "From Si Nanowires to Ge Nanocrystals for VIS-NIR-SWIR Sensors and\n  Non-volatile Memories: A Review: Nanocrystalline Si and Ge are of high interest for integrated Si photonics\nrelated to light emission, optical sensors, photodetectors, solar energy\nharvesting and conversion devices, and also for floating gate non-volatile\nmemories (NVMs). In this review, we have focused on nanocrystalline porous Si\n(nc-PS) with extension to Si nanodots, and Ge nanocrystals (NCs)/quantum dots\n(QDs)/nanoparticles (NPs) embedded in oxides (SiO$_2$, TiO$_2$, HfO$_2$,\nAl$_2$O$_3$). The great asset of nc-PS is its intense photoluminescence in VIS\nat room temperature (RT), while Ge NCs/NPs embedded in oxides show high\nphotosensitivity in VIS-NIR-SWIR in the spectral photocurrent up to 1325 nm at\nRT. Ge NCs/NPs/QDs floating gate NVMs present high memory performance, the\nretention characteristics corresponding to the state of the art for NCs\nfloating gate NVMs. We prove the relevance of controlling the preparation\nparameters for obtaining films with targeted photoluminescence,\nphotosensitivity and charge storage properties for applications, e.g.\nVIS-NIR-SWIR optical sensors and photodetectors, and electronic and\nphotoelectric NVMs. We evidence the correlation of preparation conditions,\nmorphology, composition and crystalline structure with optical, electrical,\nphotoelectrical and charge storage properties and also evidence the\ncontribution of quantum confinement effect, localized states and trapping\ncenters."
    },
    {
        "anchor": "On the Mott formula for thermopower of non-interactions electrons in\n  quantum point contacts: We calculate the linear response thermopower S of a quantum point contact\nusing the Landauer formula and therefore assume non-interacting electrons. The\npurpose of the paper, is to compare analytically and numerically the linear\nthermopower S of non-interacting electrons to the low temperature\napproximation, S^1=(pi^2/3e)k^2 T d(ln G(mu,T=0))/dmu, and the so-called Mott\nexpression, S^M=(pi^2/3e)k^2 T d(ln G(mu,T))/dmu, where G(mu,T) is the\n(temperature dependent) conductance. This comparison is important, since the\nMott formula is often used to detect deviations from single-particle behavior\nin the thermopower of a point contact.",
        "positive": "Transport in a thin topological insulator with potential and magnetic\n  barriers: We study transport across either a potential or a magnetic barrier which is\nplaced on the top surface of a three-dimensional thin topological insulator\n(TI). For such thin TIs, the top and bottom surfaces interact via a coupling\n$\\lambda$ which influences the transport properties of junctions constructed\nout of them. We find that for junctions hosting a potential barrier, the\ndifferential conductance oscillates with the barrier strength. The period of\nthese oscillations doubles as the coupling $\\lambda$ changes from small values\nto a value close to the energy of the incident electrons. In contrast, for\njunctions with a magnetic barrier, the conductance approaches a non-zero\nconstant as the barrier strength is increased. This feature is in contrast to\nthe case of transport across a single TI surface where the conductance\napproaches zero as the strength of a magnetic barrier is increased. We also\nstudy the spin currents for these two kinds of barriers; in both cases, the\nspin current is found to have opposite signs on the top and bottom surfaces.\nThus this system can be used to split applied charge currents to spin currents\nwith opposite spin orientations which can be collected by applying opposite\nspin-polarized leads to the two surfaces. We show that several of these\nfeatures of transport across finite width barriers can be understood\nanalytically by studying the $\\delta$-function barrier limit. We discuss\nexperiments which may test our theory."
    },
    {
        "anchor": "Reduction of Activation Energy Barrier of Stone-Wales Transformation in\n  Endohedral Metallofullerenes: We examine effects of encapsulated metal atoms inside a C$_{60}$ molecule on\nthe activation energy barrier to the Stone-Wales transformation using {\\it ab\ninitio} calculations. The encapsulated metal atoms we study are K, Ca and La\nwhich nominally donate one, two and three electrons to the C$_{60}$ cage,\nrespectively. We find that isomerization of the endohedral metallofullerene via\nthe Stone-Wales transformation can occur more easily than that of the empty\nfullerene owing to the charge transfer. When K, Ca and La atoms are\nencapsulated inside the fullerene, the activation energy barriers are lowered\nby 0.30, 0.55 and 0.80 eV, respectively compared with that of the empty\nC$_{60}$ (7.16 eV). The lower activation energy barrier of the Stone-Wales\ntransformation implies the higher probability of isomerization and coalescence\nof metallofullerenes, which require a series of Stone-Wales transformations.",
        "positive": "Universal Aspects of Coulomb Frustrated Phase Separation: We study the consequences of Coulomb interactions on a system undergoing a\nputative first order phase transition. In two dimensions (2D), near the\ncritical density, the system is universally unstable to the formation of new\nintermediate phases, which we call ``electronic microemulsion phases,'' which\nconsist of an intermediate scale mixture of regions of the two competing\nphases. A correlary is that there can be no direct transition as a function of\ndensity from a 2D Wigner crystal to a uniform electron liquid. In 3D, %we find\nthat if the strength of the Coulomb interactions exceeds a critical value, no\nphase separation occurs, while for weaker Coulomb strength, electronic\nmicroemulsions are inevitable. This tendency is considerably more pronounced in\nanisotropic (quasi 2D or quasi 1D) systems, where a devil's staircase of\ntransitions is possible."
    },
    {
        "anchor": "Charge dynamics in the 2D/3D semiconductor heterostructure WSe$_2$/GaAs: Understanding the relaxation and recombination processes of excited states in\ntwo-dimensional (2D)/three-dimensional (3D) semiconductor heterojunctions is\nessential for developing efficient optical and (opto)electronic devices which\nintegrate new 2D materials with more conventional 3D ones. In this work, we\nunveil the carrier dynamics and charge transfer in a monolayer of WSe$_2$ on a\nGaAs substrate. We use time-resolved differential reflectivity to study the\ncharge relaxation processes involved in the junction and how they change when\ncompared to an electrically decoupled heterostructure, WSe$_2$/hBN/GaAs. We\nobserve that the monolayer in direct contact with the GaAs substrate presents\nlonger optically-excited carrier lifetimes (3.5 ns) when compared with the\nhBN-isolated region (1 ns), consistent with a strong reduction of radiative\ndecay and a fast charge transfer of a single polarity. Through low-temperature\nmeasurements, we find evidence of a type-II band alignment for this\nheterostructure with an exciton dissociation that accumulates electrons in the\nGaAs and holes in the WSe$_2$. The type-II band alignment and fast\nphoto-excited carrier dissociation shown here indicate that WSe$_2$/GaAs is a\npromising junction for new photovoltaic and other optoelectronic devices,\nmaking use of the best properties of new (2D) and conventional (3D)\nsemiconductors.",
        "positive": "The Statistical Theory of Quantum Dots: A quantum dot is a sub-micron-scale conducting device containing up to\nseveral thousand electrons. Transport through a quantum dot at low temperatures\nis a quantum-coherent process. This review focuses on dots in which the\nelectron's dynamics are chaotic or diffusive, giving rise to statistical\nproperties that reflect the interplay between one-body chaos, quantum\ninterference, and electron-electron interactions. The conductance through such\ndots displays mesoscopic fluctuations as a function of gate voltage, magnetic\nfield, and shape deformation. The techniques used to describe these\nfluctuations include semiclassical methods, random-matrix theory, and the\nsupersymmetric nonlinear $\\sigma$ model. In open dots, the approximation of\nnoninteracting quasiparticles is justified, and electron-electron interactions\ncontribute indirectly through their effect on the dephasing time at finite\ntemperature. In almost-closed dots, where conductance occurs by tunneling, the\ncharge on the dot is quantized, and electron-electron interactions play an\nimportant role. Transport is dominated by Coulomb blockade, leading to peaks in\nthe conductance that at low temperatures provide information on the dot's\nground-state properties. Several statistical signatures of electron-electron\ninteractions have been identified, most notably in the dot's addition spectrum.\nThe dot's spin, determined partly by exchange interactions, can also influence\nthe fluctuation properties of the conductance. Other mesoscopic phenomena in\nquantum dots that are affected by the charging energy include the fluctuations\nof the cotunneling conductance and mesoscopic Coulomb blockade."
    },
    {
        "anchor": "Spin-orbit coupling in wurtzite quantum wells: Effective spin-orbit (SO) Hamiltonians for conduction electrons in wurtzite\nheterostructures are lacking in the literature, in contrast to zincblende\nstructures. Here we address this issue by deriving such an effective\nHamiltonian valid for quantum wells, wires, and dots with arbitrary confining\npotentials and external magnetic fields. We start from an 8$\\times$8 Kane model\naccounting for the $s$--$p_z$ orbital mixing important to wurtzite structures,\nbut absent in zincblende, and apply both quasi-degenerate perturbation theory\n(L\\\"owdin partitioning) and the folding down approach to derive an effective\n2$\\times$2 electron Hamiltonian. We obtain the usual $k$-linear Rashba term\narising from the structural inversion asymmetry of the wells and, differently\nfrom zincblende structures, a bulk Rashba-type term induced by the inversion\nasymmetry of the wurtzite lattice. We also find linear- and cubic-in-momentum\nDresselhaus contributions. Both the bulk Rashba-type term and the Dresselhaus\nterms originate exclusively from the admixture of $s$- and $p_z$-like states in\nwurtzites structures. Interestingly, in these systems the linear Rashba and the\nDresselhaus terms have the same symmetry and can in principle cancel each other\nout completely, thus making the spin a conserved quantity. We determine the\nintrasubband (intersubband) Rashba $\\alpha_\\nu$ ($\\eta$) and linear Dresselhaus\n$\\beta_\\nu$ ($\\Gamma$) SO strengths of GaN/AlGaN single and double wells with\none and two occupied subbands ($\\nu=1,2$). We believe our general effective\nHamiltonian for electrons in wurtzite heterostructures put forward here, should\nstimulate additional theoretical works on wurtzite quantum wells, wires, and\ndots with variously defined geometries and external magnetic fields.",
        "positive": "Origin of rebounds with a restitution coefficient larger than unity in\n  nanocluster collisions: We numerically investigate the mechanism of super rebounds for head-on\ncollisions between nanoclusters in which the restitution coefficient is larger\nthan unity. It is confirmed that the temperature and the entropy of the\nnanocluters decrease after the super rebounds by our molecular dynamics\nsimulations. It is also found that the initial metastable structure plays a key\nrole for the emergence of the super rebounds."
    },
    {
        "anchor": "Quartet states in two-electron quantum dots in bilayer graphene: Trapping electrons in quantum dots and controlling their collective quantum\nstates is crucial for converting semiconductor structures into bits of quantum\ninformation processing. Here, we study single- and two-particle states in\nquantum dots formed in gapped bilayer graphene (BLG), where the electron's\nvalley states appear in pair with their spin quantum number and we analyse\nspin- and valley-singlet and triplet states for various BLG and dot parameters,\nas well as two-particle interaction strength and external magnetic field.",
        "positive": "dmu/dn In suspended bilayer graphene: the interplay of disorder and band\n  gap: We present an interpretation of recent experimental measurements of dmu/dn in\nsuspended bilayer graphene samples. We demonstrate that the data may be\nquantitatively described by assuming a spatially varying band gap induced by\nlocal electric fields. We demonstrate that the gap fluctuations vary amongst\ndifferent samples and that the gap fluctuations are correlated with the\nassociated charge density fluctuations, indicating that the mechanism causing\nthis effect is likely to be an extrinsic effect. We also provide predictions\nfor the optical conductivity and mobility of suspended bilayer graphene samples\nwith small band gaps."
    },
    {
        "anchor": "Polaronic effects in monolayer black phosphorus on polar substrates: We investigate the effect of charge carrier interaction with surface optical\nphonons on the band properties of monolayer black phosphorus induced by polar\nsubstrates. We develop an analytical method based on the Lee-Low-Pines theory\nto calculate the spectrum of Fr\\\"ohlich type continuum Hamiltonian in the\nlong-wavelength limit. We examine the modification of a band gap and\nrenormalization of effective masses due to the substrate-related polaronic\neffect. Our results show that an energy gap in supported monolayer black\nphosphorus is enlarged depending on a particular substrate and the interlayer\ndistance, $z$. Among the substrate considered, the largest gap broadening at $\nz=2.5$ \\AA{} is observed for the Al$_{2} $O$_{3} $ substrate, which is found to\nbe $ \\sim 50$ meV. Carrier-phonon coupling also renormalizes the effective\nmasses which is more pronounced along the zigzag direction. Anisotropy of the\neffective masses becomes stronger by the influence of the polaronic effect\ncorresponding to direction-dependent carrier-phonon coupling. We conclude that\nsubstrate phonons have a non-negligible effect on the static band properties of\nmonolayer black phosphorus, which may be further exploited in its experimental\nand theoretical studies.",
        "positive": "Current correlations for the transport of interacting electrons through\n  parallel quantum dots in a photon cavity: We calculate the current correlations for the steady-state electron transport\nthrough multi-level parallel quantum dots embedded in a short quantum wire,\nthat is placed in a non-perfect photon cavity. We account for the\nelectron-electron Coulomb interaction, and the para- and diamagnetic\nelectron-photon interactions with a stepwise scheme of configuration\ninteractions and truncation of the many-body Fock spaces. In the spectral\ndensity of the temporal current-current correlations we identify all the\ntransitions, radiative and non-radiative, active in the system in order to\nmaintain the steady state. We observe strong signs of two types of Rabi\noscillations."
    },
    {
        "anchor": "Fluctuations in a mesoscopic superconducting ring: resonant behavior of\n  conductivity and specific heat in two mode critical regime: The critical fluctuations in a mesoscopic superconducting ring are studied\nwithin the Ginzburg-Landau approach. The nonlocal conductivity as well as the\nspecific heat are calculated as functions of the magnetic flux $\\Phi$ through\nthe ring. At $\\Phi=\\Phi_0/2$ two low-energy eigenstates become degenerate and\nnear this point the behavior of fluctuations-dependent quantities change\ndramatically: both the zero Fourier component $\\sigma_0$ of the fluctuation\nconductivity and the specific heat become non-monotonic functions of\n$|\\Phi-\\Phi_0/2|$ with rather special resonant structure.",
        "positive": "Atomistic and continuum modeling of a zincblende quantum dot\n  heterostructure: A multiscale approach was adopted for the calculation of confined states in\nself-assembled semiconductor quantum dots (QDs). While results close to\nexperimental data have been obtained with a combination of atomistic strain and\ntight-binding (TB) electronic structure description for the confined quantum\nstates in the QD, the TB calculation requires substantial computational\nresources. To alleviate this problem an integrated approach was adopted to\ncompute the energy states from a continuum 8-band k.p Hamiltonian under the\ninfluence of an atomistic strain field. Such multi-scale simulations yield a\nroughly six-fold faster simulation. Atomic-resolution strain is added to the\nk.p Hamiltonian through interpolation onto a coarser continuum grid. Sufficient\nnumerical accuracy is obtained by the multi-scale approach. Optical transition\nwavelengths are within 7% of the corresponding TB results with a proper\nsplitting of p-type sub-bands. The systematically lower emission wavelengths in\nk.p are attributable to an underestimation of the coupling between the\nconduction and valence bands."
    },
    {
        "anchor": "A Coherent Nonlinear Optical Signal Induced by Electron Correlations: The correlated behavior of electrons determines the structure and optical\nproperties of molecules, semiconductor and other systems. Valuable information\non these correlations is provided by measuring the response to femtosecond\nlaser pulses, which probe the very short time period during which the excited\nparticles remain correlated. The interpretation of four-wave-mixing techniques,\ncommonly used to study the energy levels and dynamics of many-electron systems,\nis complicated by many competing effects and overlapping resonances. Here we\npropose a coherent optical technique, specifically designed to provide a\nbackground-free probe for electronic correlations in many-electron systems. The\nproposed signal pulse is generated only when the electrons are correlated,\nwhich gives rise to an extraordinary sensitivity. The peak pattern in\ntwo-dimensional plots, obtained by displaying the signal vs. two frequencies\nconjugated to two pulse delays, provides a direct visualization and specific\nsignatures of the many-electron wavefunctions.",
        "positive": "Finite-frequency current (shot) noise in coherent resonant tunneling\n  through a coupled-quantum-dot interferometer: We examine the shot noise spectrum properties of coherent resonant tunneling\nin coupled quantum dots in both series and parallel arrangements by means of\nquantum rate equations and MacDonald's formula. Our results show that, for a\nseries-CQD with a relatively high dot-dot hopping $\\Omega$,\n$\\Omega/\\Gamma\\gtrsim 1$ ($\\Gamma$ denotes the dot-lead tunnel-coupling\nstrength), the noise spectrum exhibits a dip at the Rabi frequency, $2\\Omega$,\nin the case of noninteracting electrons, but the dip is supplanted by a peak in\nthe case of strong Coulomb repulsion; furthermore, it becomes a dip again for a\ncompletely symmetric parallel-CQD by tuning enclosed magnetic-flux."
    },
    {
        "anchor": "Magnetic-field-induced binding of few-electron systems in shallow\n  quantum dots: Binding of few-electron systems in two-dimensional potential cavities in the\npresence of an external magnetic field is studied with the exact\ndiagonalization approach. We demonstrate that for shallow cavities the\nfew-electron system becomes bound only under the application of a strong\nmagnetic field. The critical value of the depth of the cavity allowing the\nformation of a bound state decreases with magnetic field in a non-smooth\nfashion, due to the increasing angular momentum of the first bound state. In\nthe high magnetic field limit the binding energies and the critical values for\nthe depth of the potential cavity allowing the formation of a bound system tend\nto the classical values.",
        "positive": "Synchronization in the BCS Pairing Dynamics as a Critical Phenomenon: Fermi gas with time-dependent pairing interaction hosts several different\ndynamical states. Coupling between the collective BCS pairing mode and\nindividual Cooper pair states can make the latter either synchronize or\ndephase. We describe transition from phase-locked undamped oscillations to\nLandau-damped dephased oscillations in the collisionless, dissipationless\nregime as a function of coupling strength. In the dephased regime, we find a\nsecond transition at which the long-time asymptotic pairing amplitude vanishes.\nUsing a combination of numerical and analytical methods we establish a\ncontinuous (type II) character of both transitions."
    },
    {
        "anchor": "Thermoelectric response of Josephson junction: from ballistic to\n  disordered: It is known that Josephson junction (JJ) hosting scattering centers with\nenergy-dependent scattering amplitudes which breaks the\n$\\omega\\rightarrow-\\omega$ symmetry (where $\\omega$ is the excitation energy of\nelectron about the Fermi level) exhibits finite thermoelectric response. In\ncontrast, here we show that even in a ballistic JJ this symmetry is broken and\nit leads to a non-zero thermoelectric response when the junction length is of\nthe order of coherence length of the superconductor and the corresponding\nthermoelectric coefficient confirms to the universal sinusoidal dependence on\n$\\phi_{12}$, where $\\phi_{12}$ is the superconducting phase bias. In presence\nof multiple scatterers in the junction region, we have numerically shown that\nthe sign of the even-in-$\\phi_{12}$ part of the thermoelectric coefficient\nfluctuates violently from one disorder configuration to another hence averaging\nto vanishingly small values while the odd part tends towards the universal\nsinusoidal dependence on $\\phi_{12}$ as we approach the large disorder limit\nunder disorder averaging.",
        "positive": "Magnetic response of non-interacting and interacting electrons in a\n  M\u00f6bius strip: We investigate characteristic features of both non-interacting and\ninteracting electrons in a M\\\"{o}bius strip, the simplest possible one-sided\ntopological system, in presence of an Aharonov-Bohm flux $\\phi$. Using\nHartree-Fock mean field theory we determine energy eigenvalues for the\ninteracting model, while for the non-interacting system an analytical\nprescription is given. The interplay between longitudinal and vertical motions\nof electrons along with on-site Hubbard interaction yield several anomalous\nfeatures of persistent current associated with energy-flux characteristics. The\nvariation of current with system size and its temperature dependences are also\ncritically examined. Current is highly sensitive to both these two factors, and\nwe find that for a particular system size it decreases exponentially with\ntemperature. Our analysis can be helpful in investigating electronic transport\nthrough any non-trivial topological material."
    },
    {
        "anchor": "Modification of perpendicular magnetic anisotropy and domain wall\n  velocity in Pt/Co/Pt by voltage-induced strain: The perpendicular magnetic anisotropy K$_e$$_f$$_f$, magnetization reversal,\nand field-driven domain wall velocity in the creep regime are modified in\nPt/Co(0.85-1.0 nm)/Pt thin films by strain applied via piezoelectric\ntransducers. K$_e$$_f$$_f$, measured by the extraordinary Hall effect, is\nreduced by 10 kJ/m$^3$ by tensile strain out-of-plane {\\epsilon}$_z$ = 9 x\n10-4, independently of the film thickness, indicating a dominant volume\ncontribution to the magnetostriction. The same strain reduces the coercive\nfield by 2-4 Oe, and increases the domain wall velocity measured by wide-field\nKerr microscopy by 30-100 %, with larger changes observed for thicker Co\nlayers. We consider how strain-induced changes in the perpendicular magnetic\nanisotropy can modify the coercive field and domain wall velocity.",
        "positive": "Equilibrium Field Theory of Magnetic Monopoles in Degenerate Square Spin\n  Ice: Correlations, Entropic Interactions, and Charge Screening Regimes: We describe degenerate square spin as an ensemble of magnetic monopoles\ncoupled via an emergent entropic field that subsumes the effect of the\nunderlying spin vacuum. We compute their effective free energy, entropic\ninteraction, correlations, screening, and structure factors that coincide with\nthe experimental ones. Unlike in pyrochlore ices, a dimensional mismatch\nbetween real and entropic interactions leads to weak singularities at the pinch\npoints and algebraic correlations at long distance. This algebraic screening\ncan be, however, camouflaged by a pseudo-screening regime."
    },
    {
        "anchor": "A Backscattering Model Incorporating the Effective Carrier Temperature\n  in Nano MOSFET: In this work we propose a channel backscattering model in which increased\ncarrier temperature at the top of the potential energy barrier in the channel\nis taken into account. This model represents an extension of a previous model\nby the same authors which highlighted the importance of considering the\npartially ballistic transport between the source contact and the top of the\npotential energy barrier in the channel. The increase of carrier temperature is\nprecisely due to energy dissipation between the source contact and the top of\nthe barrier caused by the high saturation current. To support our discussion,\naccurate 2D full band Monte Carlo device simulations with quantum correction\nhave been performed in double gate nMOSFETs for different geometries (gate\nlength down to 10 nm), biases and lattice temperatures. Including the effective\ncarrier temperature is especially important to properly treat the high\ninversion regime, where previous backscattering models usually fail.",
        "positive": "Disentangling the Complex Electronic Structure of an Adsorbed\n  Nanographene: Cycloarene C108: We combine low-temperature scanning tunneling spectroscopy, CO functionalized\ntips and algorithmic data analysis to investigate the electronic structure of\nthe molecular cycloarene C108 (graphene nanoring) adsorbed on a Au(111)\nsurface. We demonstrate that CO functionalized tips enhance the visibility of\nmolecular resonances, both in differential conductance spectra and in\nreal-space topographic images without introducing spurious artifacts. Comparing\nour experimental data with ab-initio density functional theory reveals a\nremarkably precise agreement of the molecular orbitals and enables us to\ndisentangle close-lying molecular states only separated by 50 meV at an energy\nof 2 eV below the Fermi level. We propose this combination of techniques as a\npromising new route for a precise characterization of complex molecules and\nother physical entities which have electronic resonances in the tip-sample\njunction."
    },
    {
        "anchor": "Systematic spatial and stoichiometric screening towards understanding\n  the surface of ultrasmall oxygenated silicon nanocrystal: In most of the realistic ab initio and model calculations which have appeared\non the emission of light from Si nanocrystals, the role of surface oxygen has\nbeen usually ignored, underestimated or completely ruled out. We investigate\ntheoretically, by density functional theory (DFT/B3LYP) possible modes of\noxygen bonding in hydrogen terminated silicon quantum dots using as a\nrepresentative case of the Si29 nanocrystal. We have considered Bridge-bonded\noxygen (BBO), Doubly-bonded oxygen (DBO), hydroxyl (OH) and Mix of these\noxidizing agents. Due to stoichiometry, all comparisons performed are unbiased\nwith respect to composition whereas spatial distribution of oxygen species\npointed out drastic change in electronic and cohesive characteristics of\nnanocrytals. From an overall perspective of this study, it is shown that bridge\nbonded oxygenated nanocrystals accompanied by Mix have higher binding energies\nand large electronic gap compared to nanocrystals with doubly bonded oxygen\natoms. In addition, it is observed that the presence of OH along with BBO, DBO\nand mixed configurations further lowers electronic gaps and binding energies\nand trends. It is also demonstrated that oxidizing constituent besides their\nspatial distribution significantly alters binding energy and highest occupied\nmolecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) gap\n(HOMO-LUMO gap up to 1.48 eV) within same composition.",
        "positive": "Realization of graphene logics in an exciton-enhanced insulating phase: For two decades, two-dimensional carbon species, including graphene, have\nbeen the core of research in pursuing next-generation logic applications beyond\nthe silicon technology. Yet the opening of a gap in a controllable range of\ndoping, whilst keeping high conductance outside of this gapped state, has\nremained a grand challenge in them thus far. Here we show that, by bringing\nBernal-stacked bilayer graphene in contact with an anti-ferromagnetic insulator\nCrOCl, a strong insulating behavior is observed in a wide range of positive\ntotal electron doping $n_\\mathrm{tot}$ and effective displacement field\n$D_\\mathrm{eff}$ at low temperatures. Transport measurements further prove that\nsuch an insulating phase can be well described by the picture of an inter-layer\nexcitonic state in bilayer graphene owing to electron-hole interactions. The\nconsequential over 1 $\\mathrm{G\\Omega}$ excitonic insulator can be readily\nkilled by tuning $D_\\mathrm{eff}$ and/or $n_\\mathrm{tot}$, and the system\nrecovers to a high mobility graphene with a sheet resistance of less than 100\n$\\mathrm{\\Omega}$. It thus yields transistors with \"ON-OFF\" ratios reaching\n10$^{7}$, and a CMOS-like graphene logic inverter is demonstrated. Our findings\nof the robust insulating phase in bilayer graphene may be a leap forward to\nfertilize the future carbon computing."
    },
    {
        "anchor": "Thermal Collapse of a Skyrmion: Thermal collapse of an isolated skyrmion on a two-dimensional spin lattice\nhas been investigated. The method is based upon solution of the system of\nstochastic Landau-Lifshitz-Gilbert equations for up $10^4$ spins. Recently\ndeveloped pulse-noise algorithm has been used for the stochastic component of\nthe equations. The collapse rate follows the Arrhenius law. Analytical formulas\nderived within a continuous spin-field model support numerically-obtained\nvalues of the energy barrier and the pre-exponential factor, and their\ndependence on the magnetic field. Our findings agree with experiments, as well\nas with recent numerical results obtained by other methods.",
        "positive": "Electron-Hole Asymmetry in the Electron-phonon Coupling in Top-gated\n  Phosphorene Transistor: Using in-situ Raman scattering from phosphorene channel in an\nelectrochemically top-gated field effect transistor, we show that its phonons\nwith A$_g$ symmetry depend much more strongly on concentration of electrons\nthan that of holes, while the phonons with B$_g$ symmetry are insensitive to\ndoping. With first-principles theoretical analysis, we show that the observed\nelecton-hole asymmetry arises from the radically different constitution of its\nconduction and valence bands involving $\\pi$ and $\\sigma$ bonding states\nrespectively, whose symmetry permits coupling with only the phonons that\npreserve the lattice symmetry. Thus, Raman spectroscopy is a non-invasive tool\nfor measuring electron concentration in phosphorene-based nanoelectronic\ndevices."
    },
    {
        "anchor": "Strain induced topological phase transition at zigzag edges of monolayer\n  transition-metal dichalcogenides: The effect of strain in zigzag ribbons of monolayer transition-metal\ndichalcogenides with induced superconductivity is studied using a minimal\n3-band tight-binding model. The unstrained system shows a topological phase\nwith Majorana zero modes localized at the boundaries of the one-dimensional\n(1D) zigzag edges. By direct inspection of the spectrum and wave functions we\nexamine the evolution of the topological phase as an in-plane, uniaxial\ndeformation is imposed. It is found that strain shifts the energy of 1D edge\nstates, thus causing a topological phase transition which eliminates the\nMajorana modes. For realistic parameter values, we show that the effect of\nstrain can be changed from completely destructive -- in which case a small\nbuilt in strain is enough to destroy the topological phase -- to a situation\nwhere strain becomes an effective tuning parameter which can be used to\nmanipulate Majorana zero modes. These two regimes are accessible by increasing\nthe value of the applied Zeeman field within realistic values. We also study\nhow strain effects are affected by the chemical potential, showing in\nparticular how unwanted effects can be minimized. Finally, as a cross-check of\nthe obtained results, we reveal the connection between 1D Majorana zero modes\nin the zigzag edge and the multi-band Berry phase, which serves as a\ntopological invariant of this system.",
        "positive": "Graphene Transport at High Carrier Densities using a Polymer Electrolyte\n  Gate: We report the study of graphene devices in Hall-bar geometry, gated with a\npolymer electrolyte. High densities of 6 $\\times 10^{13}/cm^{2}$ are\nconsistently reached, significantly higher than with conventional back-gating.\nThe mobility follows an inverse dependence on density, which can be correlated\nto a dominant scattering from weak scatterers. Furthermore, our measurements\nshow a Bloch-Gr\\\"uneisen regime until 100 K (at 6.2 $\\times10^{13}/cm^{2}$),\nconsistent with an increase of the density. Ubiquitous in our experiments is a\nsmall upturn in resistivity around 3 $\\times10^{13}/cm^{2}$, whose origin is\ndiscussed. We identify two potential causes for the upturn: the renormalization\nof Fermi velocity and an electrochemically-enhanced scattering rate."
    },
    {
        "anchor": "Shift photoconductivity in the Haldane model: The shift current is part of the second-order optical response of materials\nwith a close connection to topology. Here we report a sign inversion in the\nband-edge shift photoconductivity of the Haldane model when the system\nundergoes a topological phase transition. This result is obtained following two\ncomplementary schemes. On one hand, we derive an analytical expression for the\nband-edge shift current in a two-band tight-binding model showing that the sign\nreversal is driven by the mass term. On the other hand, we perform a numerical\nevaluation on a continuum version of the Haldane model. This approach allows us\nto include off-diagonal matrix elements of the position operator, which are\ndiscarded in tight-binding models but can contribute significantly to the shift\ncurrent. Explicit evaluation of the shift current shows that while the model\npredictions remain accurate in the deep tight-binding regime, significant\ndeviations arise for shallow potential landscapes. Notably, the sign reversal\nacross the topological phase transition is observed in all regimes, implying it\nis a robust effect that could be observable in a wide range of topological\ninsulators.",
        "positive": "Spontaneous formation of a pi soliton in a superconducting wire with an\n  odd number of electrons: We consider a one-dimensional superconducting wire where the total number of\nelectrons can be controlled in the Coulomb blockade regime. We predict that a\npi soliton (kink) will spontaneously form in the system when the number of\nelectron is odd, because this configuration has a lower energy. If the wire\nwith an odd number of electrons is closed in a ring, the phase difference on\nthe two sides of the soliton will generate a supercurrent detectable by SQUID.\nThe two degenerate states with the current flowing clockwise or\ncounterclockwise can be utilized as a qubit."
    },
    {
        "anchor": "Enormous enhancement of p-orbital magnetism and band gap in the lightly\n  doped carbyne: This paper presents a path to tailor adapted magnetic and optical properties\nin carbyne. Although p-orbital magnetism is generally much weaker than\nd-orbital magnetism, we demonstrate that the charge fluctuation of the free\nradical electrons triggered by a time-varying electric dipole moment leads to\nenormous p-orbital magnetism. By introducing 25% arsenic and 12.5% fluorine\ninto the monoatomic carbon chain, the magnetic moment of the arsenic atom\nreaches 2.9 Bohr Magneton, which is ~1.3 times stronger than magnetic moment of\nbulk Fe. This magnetically optimized carbyne composite carries an\nexchange-correlation energy of 22meV (~270K). On the other hand, we convert the\ncarbyne (in beta-form) from metallic to a semiconducting state by using anionic\ndopants. After doping 12.5% nitrogen and 12.5% oxygen into the beta-carbyne,\nthe semiconducting gap of this composite is optimized at 1.6eV, which is 1.4\ntimes larger than the band gap of bulk silicon.",
        "positive": "Contact-induced doping in aluminum-contacted molybdenum disulfide: The interface between two-dimensional semiconductors and metal contacts is an\nimportant topic of research of nanoelectronic devices based on two-dimensional\nsemiconducting materials such as molybdenum disulfide (MoS2). We report\ntransport properties of thin MoS2 flakes in a field-effect transistor geometry\nwith Ti/Au and Al contacts. In contrast to widely used Ti/Au contacts, the\nconductance of flakes with Al contacts exhibits a smaller gate-voltage\ndependence, which is consistent with a substantial electron doping effect of\nthe Al contacts. The temperature dependence of two-terminal conductance for the\nAl contacts is also considerably smaller than for the Ti/Au contacts, in which\nthermionic emission and thermally assisted tunneling play a dominant role. This\nresult is explained in terms of the assumption that the carrier injection\nmechanism at an Al contact is dominated by tunneling that is not thermally\nactivated."
    },
    {
        "anchor": "Noise of a superconducting magnetic flux sensor based on a proximity\n  Josephson junction: We demonstrate simultaneous measurements of DC transport properties and flux\nnoise of a hybrid superconducting magnetometer based on the proximity effect\n(superconducting quantum interference proximity transistor, SQUIPT). The noise\nis probed by a cryogenic amplifier operating in the frequency range of a few\nMHz. In our non-optimized device, we achieve minimum flux noise $\\sim\n4\\;\\mu\\Phi_0/Hz^{1/2}$, set by the shot noise of the probe tunnel junction. The\nflux noise performance can be improved by further optimization of the SQUIPT\nparameters, primarily minimization of the proximity junction length and cross\nsection. Furthermore, the experiment demonstrates that the setup can be used to\ninvestigate shot noise in other nonlinear devices with high impedance. This\ntechnique opens the opportunity to measure sensitive magnetometers including\nSQUIPT devices with very low dissipation.",
        "positive": "Fractional quantum Hall states versus Wigner crystals in wide quantum\n  wells in the half-filled lowest and second Landau levels: We investigate numerically different phases that can occur at half filling in\nthe lowest and the first excited Landau levels in wide-well twodimensional\nelectron systems exposed to a perpendicular magnetic field. Within a\ntwocomponent model that takes into account only the two lowest electronic\nsubbands of the quantum well, we derive a phase diagram that compares favorably\nwith an experimental one by Shabani et al. [Phys. Rev. B 88, 245413 (2013)]. In\naddition to the compressible composite-fermion Fermi liquid in narrow wells\nwith a substantial subband gap and the incompressible twocomponent (331)\nHalperin state, we identify in the lowest Landau level a rectangular Wigner\ncrystal occupying the second subband. This crystal may be the origin of the\nexperimentally observed insulating phase in the limit of wide wells and high\nelectronic densities. In the second Landau level, the incompressible Pfaffian\nstate, which occurs in narrow wells and large subband gaps, is also separated\nby an intermediate region from a large-well limit in which a similar\nrectangular Wigner crystal in the excited subband is the ground state, as for\nthe lowest Landau level. However, the intermediate region is characterized by\nan incompressible state that consists of two four-flux Pfaffians in each of the\ncomponents."
    },
    {
        "anchor": "Mesoscopic conductance effects in InMnAs structures: Quantum corrections to the electrical conduction of magnetic semiconductors\nare comparatively unexplored. We report measurements of time-dependent\nuniversal conductance fluctuations (TDUCF) and magnetic field dependent\nuniversal conductance fluctuations (MFUCF) in micron-scale structures\nfabricated from two different In$_{1-x}$Mn$_{x}$As thin films. TDUCF and MFUCF\nincreasing in magnitude with decreasing temperature are observed. At 4 K and\nbelow, TDUCF are suppressed at finite magnetic fields independent of field\norientation.",
        "positive": "Pattern Formation and Strong Nonlinear Interactions in Exciton-Polariton\n  Condensates: Exciton-polaritons generated by light-induced potentials can spontaneously\ncondense into macroscopic quantum states that display nontrivial spatial and\ntemporal density modulation. While these patterns and their dynamics can be\nreproduced through the solution of the generalized Gross-Pitaevskii equation, a\npredictive theory of their thresholds, oscillation frequencies, and\nmulti-pattern interactions has so far been lacking. Here we represent such an\napproach based on the linear non-Hermitian modes of the complex-valued\nlight-induced potential. We provide a simple analytic expression for the lowest\nthresholds that is able to explain the modal patterns observed in recent\nexperiments for various pump geometries. We also show that the evolution of the\ncondensate with increasing pump strength is strongly geometry dependent and can\ndisplay contrasting features such as enhancement or reduction of the spatial\nlocalization of the condensate."
    },
    {
        "anchor": "Domain Formation in v=2/3 Fractional Quantum Hall Systems: We study the domain formation in the v=2/3 fractional quantum Hall systems\nbasing on the density matrix renormalization group (DMRG) analysis. The\nground-state energy and the pair correlation functions are calculated for\nvarious spin polarizations. The results confirm the domain formation in\npartially spin polarized states, but the presence of the domain wall increases\nthe energy of partially spin polarized states and the ground state is either\nspin unpolarized state or fully spin polarized state depending on the Zeeman\nenergy. We expect coupling with external degrees of freedom such as nuclear\nspins is important to reduce the energy of partially spin polarized state.",
        "positive": "Carrier Transport in High Mobility InAs Nanowire Junctionless\n  Transistors: Ability to understand and model the performance limits of nanowire\ntransistors is the key to design of next generation devices. Here, we report\nstudies on high-mobility junction-less gate-all-around nanowire field effect\ntransistor with carrier mobility reaching 2000 cm2/V.s at room temperature.\nTemperature-dependent transport measurements reveal activated transport at low\ntemperatures due to surface donors, while at room temperature the transport\nshows a diffusive behavior. From the conductivity data, the extracted value of\nsound velocity in InAs nanowires is found to be an order less than the bulk.\nThis low sound velocity is attributed to the extended crystal defects that\nubiquitously appear in these nanowires. Analyzing the temperature-dependent\nmobility data, we identify the key scattering mechanisms limiting the carrier\ntransport in these nanowires. Finally, using these scattering models, we\nperform drift-diffusion based transport simulations of a nanowire field-effect\ntransistor and compare the device performances with experimental measurements.\nOur device modeling provides insight into performance limits of InAs nanowire\ntransistors and can be used as a predictive methodology for nanowire-based\nintegrated circuits."
    },
    {
        "anchor": "Full tunability and quantum coherent dynamics of a driven multilevel\n  system: Tunability of an artificial quantum system is crucial to its capability to\nprocess quantum information. However, tunability usually poses significant\ndemand on the design and fabrication of a device. In this work, we demonstrate\nthat Floquet engineering based on longitudinal driving provides distinct\npossibilities in enhancing the tunability of a quantum system without needing\nadditional resources. In particular, we study a multilevel model based on\ngate-defined double quantum dots, where coherent interference occurs when the\nsystem is driven longitudinally. We develop an effective model to describe the\ndriven dynamics of this multilevel system, and show that it is highly tunable\nvia the driving field. We then illustrate the versatility and rich physics of a\ndriven multilevel system by exploring phenomena such as driving modulation of\nresonances, adiabatic state transfer, and dark state. In the context of qubit\ncontrol, we propose noise-resistant quantum gates based on adiabatic passage.\nThe theoretical consideration we present here is rather general, and is in\nprinciple valid for other multilevel quantum systems.",
        "positive": "Valley and Zeeman Splittings in Multilayer Epitaxial Graphene Revealed\n  by Circular Polarization Resolved Magneto-infrared Spectroscopy: Circular polarization resolved magneto-infrared studies of multilayer\nepitaxial graphene (MEG) are performed using tunable quantum cascade lasers in\nhigh magnetic fields up to 17.5 T. Landau level (LL) transitions in the\nmonolayer and bilayer graphene inclusions of MEG are resolved, and considerable\nelectron-hole asymmetry is observed in the extracted electronic band structure.\nFor monolayer graphene, a four-fold splitting of the $n=0$ to $n=1$ LL\ntransition is evidenced and attributed to the lifting of the valley and spin\ndegeneracy of the zeroth LL and the broken electron-hole symmetry. The magnetic\nfield dependence of the splitting further reveals its possible mechanisms. The\nbest fit to experimental data yields effective $g$-factors, $g^*_{VS}=6.7$ and\n$g^*_{ZS}=4.8$, for the valley and Zeeman splitting, respectively."
    },
    {
        "anchor": "Conductance fluctuations in chaotic systems with tunnel barriers: Quantum effects are expected to disappear in the short-wavelength,\nsemiclassical limit. As a matter of fact, recent investigations of transport\nthrough quantum chaotic systems have demonstrated the exponential suppression\nof the weak localization corrections to the conductance and of the Fano factor\nfor shot-noise when the Ehrenfest time exceeds the electronic dwell time. On\nthe other hand, conductance fluctuations, an effect of quantum coherence,\nretain their universal value in the limit of the ratio of Ehrenfest time over\ndwell time to infinity, when the system is ideally coupled to external leads.\nMotivated by this intriguing result we investigate conductance fluctuations\nthrough quantum chaotic cavities coupled to external leads via (tunnel)\nbarriers of arbitrary transparency. Using the trajectory-based semiclassical\ntheory of transport, we find a linear Ehrenfest time-dependence of the\nconductance variance showing a nonmonotonous, sinusoidal behavior as a function\nof the transperancy. Most notably, we find an increase of the conductance\nfluctuations with the Ehrenfest time, above their universal value, for the\ntransparency less than 0.5. These results, confirmed by numerical simulations,\nshow that, contrarily to the common wisdom, effects of quantum coherence may\nincrease in the semiclassical limit, under special circumstances.",
        "positive": "Topological transconductance quantization in a four-terminal Josephson\n  junction: Recently we predicted that the Andreev bound state spectrum of 4-terminal\nJosephson junctions may possess topologically protected zero-energy Weyl\nsingularities, which manifest themselves in a quantized transconductance in\nunits of $4e^2/h$ when two of the terminals are voltage biased [R.-P. Riwar et\nal., Nature Commun. 7, 11167 (2016)]. Here, using the Landauer-B\\\"uttiker\nscattering theory, we compute numerically the currents flowing through such a\nstructure in order to assess the conditions for observing this effect. We show\nthat the voltage below which the transconductance becomes quantized is\ndetermined by the interplay of non-adiabatic transitions between Andreev bound\nstates and inelastic relaxation processes. We demonstrate that the topological\nquantization of the transconductance can be observed at voltages of the order\nof $10^{-2} \\Delta/e$, $\\Delta$ being the superconducting gap in the leads."
    },
    {
        "anchor": "Observation of excited states in a graphene quantum dot: We demonstrate that excited states in single-layer graphene quantum dots can\nbe detected via direct transport experiments. Coulomb diamond measurements show\ndistinct features of sequential tunneling through an excited state. Moreover,\nthe onset of inelastic cotunneling in the diamond region could be detected. For\nlow magnetic fields, the positions of the single-particle energy levels\nfluctuate on the scale of a flux quantum penetrating the dot area. For higher\nmagnetic fields, the transition to the formation of Landau levels is observed.\nEstimates based on the linear energy-momentum relation of graphene give carrier\nnumbers of the order of 10 for our device.",
        "positive": "Lagrangian approach in spin-oscillations problem: Lagrangian of electronic liquid in magneto-inhomogeneous micro-conductor has\nbeen constructed. A corresponding Euler-Lagrange equation has been solved. It\nwas shown that the described system has eigenmodes of spin polarization and\ntotal electric current oscillations. The suggested approach permits to study\nthe spin dynamics in an open-circuit which contains capacitance and/or\ninductivity."
    },
    {
        "anchor": "Strong-coupling charge density wave in a one-dimensional topological\n  metal: Scanning tunnelling microscopy and low energy electron diffraction show a\ndimerization-like reconstruction in the one-dimensional atomic chains on\nBi(114) at low temperatures. While one-dimensional systems are generally\nunstable against such a distortion, its observation is not expected for this\nparticular surface, since there are several factors that should prevent it: One\nis the particular spin texture of the Fermi surface, which resembles a\none-dimensional topological state, and spin protection should hence prevent the\nformation of the reconstruction. The second is the very short nesting vector $2\nk_F$, which is inconsistent with the observed lattice distortion. A\nnesting-driven mechanism of the reconstruction is indeed excluded by the\nabsence of any changes in the electronic structure near the Fermi surface, as\nobserved by angle-resolved photoemission spectroscopy. However, distinct\nchanges in the electronic structure at higher binding energies are found to\naccompany the structural phase transition. This, as well as the observed short\ncorrelation length of the pairing distortion, suggest that the transition is of\nthe strong coupling type and driven by phonon entropy rather than electronic\nentropy.",
        "positive": "Detection of HIV-1 antigen based on magnetic tunnel junction sensor and\n  magnetic nanoparticles: In recent years, it is evidenced that the individuals newly infected HIV are\ntransmitting the virus prior to knowing their HIV status. Identifying\nindividuals that are early in infection with HIV antibody negative (window\nperiod) remains problematic. In the newly infected individuals, HIV antigen p24\nis usually present in their serum or plasma 7-10 days before the HIV antibody.\nAfter antibody production initiates, the p24 antigen is bound into immune\ncomplexes. That means the detectable p24 antigens in serum/plasma are\nshort-lived, and their amount is in the pg/ml range. Thus, a rapid quantitative\nbio-detection system with high-sensitivity is required to achieve early disease\ndiagnosis. Magnetoresistive (MR) biosensor with ultra-high sensitivity\npossesses great potential in this area. In this study, a p24 detection assay\nusing MgO-based magnetic tunnel junction (MTJ) sensor and 20-nm magnetic\nnanoparticles is reported."
    },
    {
        "anchor": "Non-sinusoidal current-phase relationship in Josephson junctions from\n  the 3D topological insulator HgTe: We use Superconducting QUantum Interference Device (SQUID) microscopy to\ncharacterize the current-phase relation (CPR) of Josephson Junctions from\n3-dimentional topological insulator HgTe (3D-HgTe). We find clear skewness in\nthe CPRs of HgTe junctions ranging in length from 200 nm to 600 nm. The\nskewness indicates that the Josephson current is predominantly carried by\nAndreev bound states with high transmittance, and the fact that the skewness\npersists in junctions that are longer than the mean free path suggests that the\neffect may be related to the helical nature of the Andreev bound states in the\nsurface of HgTe.",
        "positive": "The Quantum Spin Hall Effect: Theory and Experiment: The search for topologically non-trivial states of matter has become an\nimportant goal for condensed matter physics. Recently, a new class of\ntopological insulators has been proposed. These topological insulators have an\ninsulating gap in the bulk, but have topologically protected edge states due to\nthe time reversal symmetry. In two dimensions the helical edge states give rise\nto the quantum spin Hall (QSH) effect, in the absence of any external magnetic\nfield. Here we review a recent theory which predicts that the QSH state can be\nrealized in HgTe/CdTe semiconductor quantum wells. By varying the thickness of\nthe quantum well, the band structure changes from a normal to an \"inverted\"\ntype at a critical thickness $d_c$. We present an analytical solution of the\nhelical edge states and explicitly demonstrate their topological stability. We\nalso review the recent experimental observation of the QSH state in\nHgTe/(Hg,Cd)Te quantum wells. We review both the fabrication of the sample and\nthe experimental setup. For thin quantum wells with well width $d_{QW}< 6.3$\nnm, the insulating regime shows the conventional behavior of vanishingly small\nconductance at low temperature. However, for thicker quantum wells ($d_{QW}>\n6.3$ nm), the nominally insulating regime shows a plateau of residual\nconductance close to $2e^2/h$. The residual conductance is independent of the\nsample width, indicating that it is caused by edge states. Furthermore, the\nresidual conductance is destroyed by a small external magnetic field. The\nquantum phase transition at the critical thickness, $d_c= 6.3$ nm, is also\nindependently determined from the occurrence of a magnetic field induced\ninsulator to metal transition."
    },
    {
        "anchor": "Quantum Hall Solitons with Intertwined Spin and Pseudospin at $\u03bd= \\\n  1$: In this paper we study in detail different types of topological solitons\nwhich are possible in bilayer quantum Hall systems at filling fraction $\\nu =1$\nwhen spin degrees of freedom are included. Starting from a microscopic\nHamiltonian we derive an effective energy functional for studying such\nexcitations. The gauge invariance and $CP^{3}$ character of this energy\nfuctional and their consequences are examined. Then we identify permissible\nclasses of finite energy solutions which are topologically non-trivial. We also\nnumerically evaulate a representative solution in which a pseudospin (layer\ndegrees of freedom) bimeron in a given spin component is intertwined with\nspin-skyrmions in each layer, and and discuss whether it is energetically\nfavoured as the lowest lying excitation in such system with some numerical\nresults.",
        "positive": "Higher Order Topological Systems: A New Paradigm: Higher order topological insulators are a new class of topological insulators\nin dimensions $\\rm d>1$. These higher-order topological insulators possess $\\rm\n(d - 1)$-dimensional boundaries that, unlike those of conventional topological\ninsulators, do not conduct via gapless states but instead are themselves\ntopological insulators. Precisely, an $\\rm n^{\\rm th}$-order topological\ninsulator in $\\rm m$ dimensions hosts $\\rm d_{c} = (m - n)$-dimensional\nboundary modes $\\rm (n \\leq m)$. For instance, a three-dimensional second\n(third) order topological insulator hosts gapless modes on the hinges\n(corners), characterized by $\\rm d_{c} = 1 (0)$. Similarly, a second order\ntopological insulator in two dimensions only has gapless corner states ($\\rm\nd_{c} = 0$) localized at the boundary. These higher order phases are protected\nby various crystalline symmetries. Moreover, in presence of proximity induced\nsuperconductivity and appropriate symmetry breaking perturbations, the above\nmentioned bulk-boundary correspondence can be extended to higher order\ntopological superconductors hosting Majorana hinge or corner modes. Such\nhigher-order systems constitute a distinctive new family of topological phases\nof matter which has been experimentally observed in acoustic systems,\nmultilayer $\\rm WTe_{2}$ and $\\rm Bi_{4}Br_{4}$ chains. In this general\narticle, the basic phenomenology of higher order topological insulators and\nhigher order topological superconductors are presented along with some of their\nexperimental realization."
    },
    {
        "anchor": "Magnetization of topological line-node semimetals: Using an approximate expression for the Landau levels of the electrons\nlocated near a nodal line of a topological line-node semimetal, we obtain\nformulas for the magnetization of this semimetal at an arbitrary shape of its\nline. It is also shown that the dependence of the chemical potential on the\nmagnetic field can be strong in these materials, and this dependence can\nessentially influence the de Haas - van Alphen oscillations. The obtained\nresults are applied to the rhombohedral graphite which is one of the line-node\nsemimetals. For this material, we find temperature and magnetic field\ndependences of its magnetic susceptibility.",
        "positive": "Localized all-optical control of single semiconductor quantum dots\n  through plasmon-polariton-induced screening: Due to their ability to strongly modify the local electromagnetic (EM) field\nthrough the excitation of surface plasmon polaritons (SPPs), plasmonic\nnanostructures have been often used to reshape the emission direction and\nenhance the radiative decay rate of quantum emitters, such as semiconductor\nquantum dots (QDs). These features are essential for quantum information\nprocessing, nanoscale photonic circuitry and optoelectronics. However, the\nmodification and enhancement demonstrated thus far often drastically alter the\nlocal energy density of the emitters, and hence their intrinsic properties,\nleaving little room for active control. Here, we demonstrate dynamic tuning of\nthe energy states of a single semiconductor QD by optically modifying its local\ndielectric environment with a nearby plasmonic structure, instead of directly\ncoupling it to the QD. This method leaves the original intrinsic optical\nproperties of the QD intact, enabling the opportunity of tuning its optical\nproperties in real time. This capability is highly desired in applications\nrequiring ultrafast switching and modulation mechanisms."
    },
    {
        "anchor": "Magnetic field-induced exchange effects between Mn ions and free\n  carriers in ZnSe quantum well through the intermediate nonmagnetic barrier\n  studied by photoluminescence: Photoluminescence (PL) of the 50 nm $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$/ $d$ nm\n$Zn_{0.943}Be_{0.057}Se$/ 2.5 nm $ZnSe$/ 30 nm $Zn_{0.943}Be_{0.057}Se$\nstructures is investigated as a function of magnetic field ($B$) and thickness\n($d$) of intermediate $Zn_{0.943}Be_{0.057}Se$ nonmagnetic barrier between the\n$Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ semimagnetic barrier and $ZnSe$ quantum well at\nthe temperature 1.2 K. The rate of the shift of different PL bands of the\nstructures under study is estimated in low and high magnetic fields. The causes\nof the shift rate increase under pass from low to high magnetic fields are\ninterpreted. The peculiarities of the effect of the intermediate barrier on the\nluminescence properties of the structures are presented. It is shown that\ndeformation of adjacent layers by the barrier plays a crucial role in the\nformation of these properties, especially in forming the $Mn$ complexes in the\n$Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ layer. The change of the band gap as well as of\nthe donor and acceptor levels energies under the effect of biaxial compression\nof the $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ layer by the $Zn_{0.943}Be_{0.057}Se$ are\nestimated. It is concluded that the $Zn_{0.943}Be_{0.057}Se$ intermediate\nbarrier also appreciably changes the effect of giant Zeeman splitting of the\nsemimagnetic $Zn_{0.9}Be_{0.05}Mn_{0.05}Se$ barrier energy levels on the\nmovement of the energy levels of $ZnSe$ quantum well in a magnetic field and on\npolarization of the quantum well exciton emission.",
        "positive": "A micro-magneto-Raman scattering study of graphene on a bulk graphite\n  substrate: We report on a magneto-Raman scattering study of graphene flakes located on\nthe surface of a bulk graphite substrate. By spatially mapping the Raman\nscattering response of the surface of bulk graphite with an applied magnetic\nfield, we pinpoint specific locations which show the electronic excitation\nspectrum of graphene. We present the characteristic Raman scattering signatures\nof these specific locations. We show that such flakes can be superimposed with\nanother flake and still exhibit a graphene-like excitation spectrum.\n  Two different excitation laser energies (514.5 and 720 nm) are used to\ninvestigate the excitation wavelength dependence of the electronic Raman\nscattering signal."
    },
    {
        "anchor": "Kondo Force in Shuttling Devices: Dynamical Probe for a Kondo Cloud: We consider electromechanical properties of a single-electronic device\nconsisting of movable quantum dot attached to a vibrating cantilever, forming a\ntunnel contact with a non-movable source electrode. We show that the resonance\nKondo tunneling of electrons amplify exponentially the strength of\nnanoelectromechanical (NEM) coupling in such device and makes the latter to be\ninsensitive to mesoscopic fluctuations of electronic levels in a nano-dot. It\nis also shown that the study of Kondo-NEM phenomenon provides an additional (as\ncompared with a standard conductance measurements in a non-mechanical device)\ninformation on retardation effects in formation of many-particle cloud\naccompanied the Kondo tunneling. A possibility for superhigh tunability of\nmechanical dissipation as well as supersensitive detection of mechanical\ndisplacement is demonstrated.",
        "positive": "Fine structure of high-power microwave-induced resistance oscillations: We report on observation of a fine structure of microwave-induced resistance\noscillations in an ultraclean two-dimensional electron gas. This fine structure\nis manifested by multiple secondary sharp extrema, residing beside the primary\nones, which emerge at high radiation power. Theoretical considerations reveal\nthat this fine structure originates from multiphoton-assisted scattering off\nshort-range impurities. Unique properties of the fine structure allow us to\naccess all experimental parameters, including microwave power, and to separate\ndifferent contributions to photoresistance. Furthermore, we show that the fine\nstructure offers a convenient means to quantitatively assess the correlation\nproperties of the disorder potential in high-quality systems, allowing\nseparation of short- and long-range disorder contributions to the electron\nmobility."
    },
    {
        "anchor": "Quantum energy flow in mesoscopic dielectric structures: We investigate the phononic energy transport properties of mesoscopic,\nsuspended dielectric wires. The Landauer formula for the thermal conductance is\nderived and its universal aspects discussed. We then determine the variance of\nthe energy current in the presence of a steady state current flow. In the final\npart, some initial results are presented concerning the nature of the\ntemperature fluctuations of a mesoscopic electron gas thermometer due to the\nabsorption and emission of wire phonons.",
        "positive": "Nonmagnetic band gap at the Dirac point of the magnetic topological\n  insulator (Bi$_{1-x}$Mn$_x)_2$Se$_3$: Magnetic doping is expected to open a band gap at the Dirac point of\ntopological insulators by breaking time-reversal symmetry and to enable novel\ntopological phases. Epitaxial (Bi$_{1-x}$Mn$_{x}$)$_{2}$Se$_{3}$ is a\nprototypical magnetic topological insulator with a pronounced surface band gap\nof $\\sim100$ meV. We show that this gap is neither due to ferromagnetic order\nin the bulk or at the surface nor to the local magnetic moment of the Mn,\nmaking the system unsuitable for realizing the novel phases. We further show\nthat Mn doping does not affect the inverted bulk band gap and the system\nremains topologically nontrivial. We suggest that strong resonant scattering\nprocesses cause the gap at the Dirac point and support this by the observation\nof in-gap states using resonant photoemission. Our findings establish a novel\nmechanism for gap opening in topological surface states which challenges the\ncurrently known conditions for topological protection."
    },
    {
        "anchor": "2D Lattice of coupled Sinai billiards: metal or insulator at g<<1: We investigate the transport in a two-dimensional (2D) lattice of coupled\nSinai billiards fabricated on the basis of a high-mobility 2D electron gas in\nGaAs/AlGaAs heterojunction. For the states with low reduced conductivity g<<1\nan anomalously weak temperature dependence of g was found. The large negative\nmagnetoresistance described by the Lorentz line-shape of the width\ncorresponding to the half magnetic flux quantum through the area of the\nbilliard is observed. In going from g>1 to g<<1 it strongly increases. The\nShubnikov-de Haas oscillations and commensurability magnetoresistance peak are\npreserved at g<<1. The data suggest that the system studied behaves more like a\nmetal than an insulator at g<<1 and is not described by the generally accepted\npicture of Anderson localization.",
        "positive": "Unconventional Bloch-Gr\u00fcneisen scattering in hybrid Bose-Fermi\n  systems: We report on the novel mechanism of electron scattering in hybrid Bose-Fermi\nsystems consisting of a two-dimensional electron gas in the vicinity of an\nexciton condensate: We show that a pair-of-bogolons--mediated scattering proves\nto be dominating over the conventional acoustic phonon channel and over the\nsingle-bogolon scattering, even if the screening is taken into account. We\ndevelop a microscopic theory of this effect, focusing on GaAs and MoS$_2$\nmaterials, and find the principal temperature dependence of resistivity,\ndistinct from the conventional phonon--mediated processes. Further, we\nscrutinize parameters and suggest a way to design composite samples with\npredefined electron mobilities and propose a mechanism of electron pairing for\nsuperconductivity."
    },
    {
        "anchor": "Engineering topological phases with a three-dimensional nodal-loop\n  semimetal: A three-dimensional (3D) nodal-loop semimetal phase is exploited to engineer\na number of intriguing phases featuring different peculiar topological surface\nstates. In particular, by introducing various two-dimensional gap terms to a 3D\ntight-binding model of a nodal-loop semimetal, we obtain a rich variety of\ntopological phases of great interest to ongoing theoretical and experimental\nstudies, including chiral insulator, degenerate-surface-loop insulator,\nsecond-order topological insulator, as well as Weyl semimetal with tunable\nFermi arc profiles. The unique concept underlying our approach is to engineer\ntopological surface states that inherit their dispersion relations from a gap\nterm. The results provide one rather unified principle for the creation of\nnovel topological phases and can guide the search for new topological\nmaterials. Two-terminal transport studies are also carried out to distinguish\nthe engineered topological phases.",
        "positive": "Universal Hall coefficient correction in strongly coupled Cr-SiO$_2$\n  nanogranular metals: The microstructure and electrical transport of Cr$_x$(SiO$_2$)$_{1-x}$\nnanogranular films with Cr volume faction $x$$\\simeq$0.67 and 0.72 are\nsystematically investigated. The transmission electron microscopy images and\nelemental mappings indicate that the films are quite inhomogeneous: some Cr\ngranules directly connect to others while some Cr granules with size $\\sim$1 to\n$\\sim$3\\,nm disperse in the SiO$_2$ dielectric matrix. For each film, the Hall\ncoefficient $R_H$ varies linearly with the natural logarithm of temperature,\ni.e., $\\Delta R_H$$\\propto$$\\ln T$, above $\\sim$60\\,K, saturates at\n$\\sim$60\\,K, and retains the saturating value below $\\sim$60\\,K. The\ntemperature dependence of Hall coefficient can be explained by the recent\ntheory in granular metals and originates from \\emph{virtual diffusion} of\nelectrons through the metallic granules. For the conductivity $\\sigma$, a\nrobust $\\Delta \\sigma$$\\propto$$\\sqrt{T}$ law is observed from $\\sim$50 down to\n2\\,K. The behavior of the conductivity stems from the ``Altshuler-Aronov\"\ncorrection, whose influence on the Hall coefficient is not present in the\nfilms."
    },
    {
        "anchor": "Engineering Enhanced Thermal Transport in Layered Nanomaterials: A comprehensive rational thermal material design paradigm requires the\nability to reduce and enhance the thermal conductivities of nanomaterials. In\ncontrast to the existing ability to reduce the thermal conductivity, methods\nthat allow to enhance heat conduction are currently limited. Enhancing the\nnanoscale thermal conductivity could bring radical improvements in the\nperformance of electronics, optoelectronics, and photovoltaic systems. Here, we\nshow that enhanced thermal conductivities can be achieved in semiconductor\nnanostructures by rationally engineering phonon spectral coupling between\nmaterials. By embedding a germanium film between silicon layers, we show that\nits thermal conductivity can be increased by more than 100% at room temperature\nin contrast to a free standing thin-film. The injection of phonons from the\ncladding silicon layers creates the observed enhancement in thermal\nconductivity. We study the key factors underlying the phonon injection\nmechanism and find that the surface roughness and layer thicknesses play a\ndetermining role. The findings presented in this letter will allow for the\ncreation of nanomaterials with an increased thermal conductivity.",
        "positive": "Electron correlations in two-dimensional small quantum dots: We consider circular and elliptic quantum dots with parabolic external\nconfinement, containing 0 - 22 electrons and with values of r_s in the range 0\n< r_s < 3. We perform restricted and unrestricted Hartree-Fock calculations,\nand further take into account electron correlations using second-order\nperturbation theory. We demonstrate that in many cases correlations\nqualitatively change the spin structure of the ground state from that obtained\nunder Hartree-Fock and spin-density-functional calculations. In some cases the\ncorrelation effects destroy Hund's rule. We also demonstrate that the\ncorrelations destroy static spin-density waves observed in Hartree-Fock and\nspin-density-functional calculations."
    },
    {
        "anchor": "Evidence for Kinetic Limitations as a Controlling Factor of Ge Pyramid\n  Formation: a Study of Structural Features of Ge/Si(001) Wetting Layer Formed\n  by Ge Deposition at Room Temperature Followed by Annealing at 600 \u00b0C: The article presents an experimental study of an issue of whether the\nformation of arrays of Ge quantum dots on the Si(001) surface is an equilibrium\nprocess or it is kinetically controlled. We deposited Ge on Si(001) at the room\ntemperature and explored crystallization of the disordered Ge film as a result\nof annealing at 600 {\\deg}C. The experiment has demonstrated that the\nGe/Si(001) film formed in the conditions of an isolated system consists of the\nstandard patched wetting layer and large droplike clusters of Ge rather than of\nhuts or domes which appear when a film is grown in a flux of Ge atoms arriving\non its surface. We conclude that the growth of the pyramids appearing at\ntemperatures greater than 600 {\\deg}C is controlled by kinetics rather than\nthermodynamic equilibrium whereas the wetting layer is an equilibrium\nstructure.",
        "positive": "Phonon-Assisted Gain in a Semiconductor Double Quantum Dot Maser: We develop a microscopic model for the recently demonstrated double quantum\ndot (DQD) maser. In characterizing the gain of this device we find that, in\naddition to the direct stimulated emission of photons, there is a large\ncontribution from the simultaneous emission of a photon and a phonon, i.e., the\nphonon sideband. We show that this phonon-assisted gain typically dominates the\noverall gain which leads to masing. Recent experimental data are well fit with\nour model."
    },
    {
        "anchor": "Fundamental limits in heat assisted magnetic recording and methods to\n  overcome it with exchange spring structures: The switching probability of magnetic elements for heat assisted recording is\ninvestigated. It is found that FePt elements with a diameter of 5 nm and a\nheight of 10nm show, at a field of 0.5 T, thermally written in errors of 12\npercent, which is significant too large for bit patterned magnetic recording.\nThermally written in errors can be decreased if larger head fields are applied.\nHowever, larger fields lead to an increase the fundamental thermal jitter. This\nleads to a dilemma between thermally written in errors and fundamental thermal\njitter. This dilemma can be partly relaxed by increasing the thickness of the\nFePt film up to 30nm. For realistic head fields, it is found that the\nfundamental thermal jitter is in the same order of magnitude of the fundamental\nthermal jitter in conventional recording, which is about 0.5 to 0.8 nm.\nComposite structures consisting of high Curie top layer and FePt as hard\nmagnetic storage layer can reduce the thermally written in errors to be smaller\nthan 10-4 if the damping constant is increased in the soft layer. Large damping\nmay be realized by doping with rare earth elements. Similar to single FePt\ngrains also in composite structure an increase of switching probability is\nsacrifices by an increase of thermal jitter. Structures utilizing first order\nphase transitions breaking the thermal jitter and writeability dilemma are\ndiscussed.",
        "positive": "Thermal Properties of the Hybrid Graphene-Metal Nano-Micro-Composites:\n  Applications in Thermal Interface Materials: The authors report on synthesis and thermal properties of the\nelectrically-conductive thermal interface materials with the hybrid\ngraphene-metal particle fillers. The thermal conductivity of resulting\ncomposites was increased by ~500% in a temperature range from 300 K to 400 K at\na small graphene loading fraction of 5-vol.-%. The unusually strong enhancement\nof thermal properties was attributed to the high intrinsic thermal conductivity\nof graphene, strong graphene coupling to matrix materials and the large range\nof the length-scale - from nanometers to micrometers - of the graphene and\nsilver particle fillers. The obtained results are important for thermal\nmanagement of advanced electronics and optoelectronics."
    },
    {
        "anchor": "Casimir interactions in graphene systems: The non-retarded Casimir interaction (van der Waals interaction) between two\nfree standing graphene sheets as well as between a graphene sheet and a\nsubstrate is determined. An exact analytical expression is given for the\ndielectric function of graphene along the imaginary frequency axis within the\nrandom phase approximation for arbitrary frequency, wave vector, and doping.",
        "positive": "Analysis of the Kondo effect in ferromagnetic atomic-sized contacts: Atomic contacts made of ferromagnetic metals present zero-bias anomalies in\nthe differential conductance due to the Kondo effect. These systems provide a\nunique opportunity to perform a statistical analysis of the Kondo parameters in\nnanostructures since a large number of contacts can be easily fabricated using\nbreak-junction techniques. The details of the atomic structure differ from one\ncontact to another so a large number of different configurations can be\nstatistically analyzed. Here we present such a statistical analysis of the\nKondo effect in atomic contacts made from the ferromagnetic transition metals\nNi, Co and Fe. Our analysis shows clear differences between materials that can\nbe understood by fundamental theoretical considerations. This combination of\nexperiments and theory allow us to extract information about the origin and\nnature of the Kondo effect in these systems and to explore the influence of\ngeometry and valence in the Kondo screening of atomic-sized nanostructures."
    },
    {
        "anchor": "Perfect Valley Filter in Topological Domain Wall: We propose a realization of perfect valley filters based on the chiral\ndomain-wall channels between a quantum anomalous Hall insulator and a quantum\nvalley Hall insulator. Uniquely, all these channels reside in the same valley\nand propagate unidirectionally, $100\\%$ valley-polarizing passing-by carriers\nwithout backscattering. The valley index, the chirality, and the number of the\nchannels are protected by topological charges, controllable by external fields,\nand detectable by circular dichroism.",
        "positive": "Floquet Topological Polaritons in Semiconductor Microcavities: We propose and model Floquet topological polaritons in semiconductor\nmicrocavities, using the interference of frequency detuned coherent fields to\nprovide a time periodic potential. For arbitrarily weak field strength, where\nthe Floquet frequency is larger than the relevant bandwidth of the system, a\nChern insulator is obtained. As the field strength is increased, a topological\nphase transition is observed with an unpaired Dirac cone proclaiming the\nanomalous Floquet topological insulator. As the relevant bandwidth increases\neven further, an exotic Chern insulator with flat band is observed with\nunpaired Dirac cone at the second critical point. Considering the polariton\nspin degree of freedom, we find that the choice of field polarization allows\noppositely polarized polaritons to either co-propagate or counter-propagate in\nchiral edge states."
    },
    {
        "anchor": "Intersubband transition engineering in the conduction band of asymmetric\n  coupled Ge/SiGe quantum wells: : n-type Ge/SiGe asymmetric-coupled quantum wells represent the building\nblock of a variety of nanoscale quantum devices, including recently proposed\ndesigns for a silicon-based THz quantum cascade laser. In this paper, we\ncombine structural and spectroscopic experiments on 20-module superstructures,\neach featuring two Ge wells coupled through a Ge-rich tunnel barrier, as a\nfunction of the geometry parameters of the design and the P dopant\nconcentration. Through the comparison of THz spectroscopic data with numerical\ncalculations of intersubband optical absorption resonances, we demonstrated\nthat it is possible to tune by design the energy and the spatial overlap of\nquantum confined subbands in the conduction band of the heterostructures. The\nhigh structural/interface quality of the samples and the control achieved on\nsubband hybridization are the promising starting point towards a working\nelectrically pumped light-emitting device.",
        "positive": "Implicit Phonon Shifts and Thermodynamical Properties of Rigid Carbon\n  Nanotube Ropes: We calculate phonon shifts of external modes of a bunch of carbon nanotubes.\nA simple model based on atom-atom potential has been used to calculate the\nimplicit anharmonicity in the phonons of carbon nanotube bundles having rigid\ntubes, with the assumption that under hydrostatic pressure only the intertube\ndistance in the bunch varies. Such a model is important as long carbon nanotube\nropes will be an extension of a fixed length ropes as is done here. Various\nbulk and thermodynamic properties like thermal expansion, bulk modulus and the\nGruneisen constants and external phonon shifts which naturally enter into the\ncalculation are also described and compared with the available data. The\nspecific heat capacity has also been calculated."
    },
    {
        "anchor": "High contrast imaging and thickness determination of graphene with\n  in-column secondary electron microscopy: We report a new method for quantitative estimation of graphene layer\nthicknesses using high contrast imaging of graphene films on insulating\nsubstrates with a scanning electron microscope. By detecting the attenuation of\nsecondary electrons emitted from the substrate with an in-column low-energy\nelectron detector, we have achieved very high thickness-dependent contrast that\nallows quantitative estimation of thickness up to several graphene layers. The\nnanometer scale spatial resolution of the electron micrographs also allows a\nsimple structural characterization scheme for graphene, which has been applied\nto identify faults, wrinkles, voids, and patches of multilayer growth in\nlarge-area chemical vapor deposited graphene. We have discussed the factors,\nsuch as differential surface charging and electron beam induced current, that\naffect the contrast of graphene images in detail.",
        "positive": "Multilevel coherences in quantum dots: We study transport through strongly interacting quantum dots with $N$ energy\nlevels that are weakly coupled to generic multi-channel metallic leads. In the\nregime of coherent sequential tunneling, where level spacing and broadening are\nof the same order but small compared to temperature, we present a unified,\n$SU(N)$-invariant form of the kinetic equation for the reduced density matrix\nof the dot and the tunneling current. This is achieved by introducing the\nconcept of flavor polarization for the dot and the reservoirs, and splitting\nthe kinetic equation in terms of flavor accumulation, anisotropic flavor\nrelaxation, as well as exchange-field- and detuning-induced flavor rotation. In\nparticular, we identify the exchange field as the cause of negative\ndifferential conductance at off-resonance bias voltages appearing in generic\nquantum-dot models. To illustrate the notion of flavor polarization, we analyze\nthe non-linear current through a triple quantum-dot device."
    },
    {
        "anchor": "Three Dimensional Liquid Gated Graphene Field Effect Strain Sensor: Realizing flexible strain sensor with high sensitivity and tunable gauge\nfactor is a challenge. To meet this challenge, we report an ionic liquid gated\nthree-dimensional graphene field effect strain sensor. The charge carrier\nconcentration in this 3D graphene is modulated by applied electric field\nthrough an all-around self-assembled electrical double layer capacitance formed\nat the interface of graphene with ionic liquid. Strain causes folding and\nunfolding of microscopic wrinkles and formation of cracks in the graphene\nnetwork altering transistor behavior. Mechanical deformation of graphene also\nalters its bandgap providing inherent strain sensitivity. Use of 3D network\nresults in robust operation since there exists multiple paths for the charge\ncarriers to flow between source and drain terminals. Interestingly, changing\nthe applied bias allows one to tune the gauge factor of this graphene\ntransistor based strain sensor. The current-voltage characteristics of the\nsensor were measured for different tensile strain values of 0.5% to 35%. Our\nresults show that the sensor maintains its field effect characteristics over a\nlarge strain range; moreover it enables up to 68% tunability in the strain\ngauge factor. We also report cyclic measurements with varied magnitude and\nfrequency showing repeatability and robustness as a highly sensitive strain\nsensor.",
        "positive": "Seebeck and Nernst effects in topological insulator: the case of\n  strained HgTe: We theoretically study the thermoelectric transport properties of strained\nHgTe in the topological insulator phase. We developed a model for the system\nusing a Dirac Hamiltonian including the effect of strain induced by the\ninterface between HgTe and the CdTe substrate. The conductivity tensor was\nexplored assuming the electrons are scattered by charge impurities, while the\nthermopower tensor was addressed using the Mott relation. Seebeck and Nernst\nresponses exhibit remarkable enhancements in comparison with other\ntwo-dimensional Dirac materials, such as graphene, germanane, prosphorene and\nstanene. The intensity of these termoeletric responses, their dependencies with\nthe external perpendicular magnetic field and temperature are also addressed."
    },
    {
        "anchor": "Ionic conductance oscillations in sub-nanometer pores probed by\n  optoelectronic control: Ionic Coulomb blockade is one of the mesoscopic effects in ion transport\nrevealing the quantized nature of ionic charges, which is of crucial importance\nto our understanding of the sub-continuum transport in nanofluidics and the\nmechanism of biological ion channels. Herein, we report an experimental\nobservation and plausible theoretical reasoning of ionic conduction\noscillations. Our experiment was performed under strong confinement in single\nsub-nanometer MoS2 pores with optoelectronic control enabled for active tuning\nof pore surface charges. Under this charge control, we measured the ionic\ncurrent at fixed voltages and observed multiple current peaks. Our analytical\ndiscussions and molecular dynamics simulations further reveal that the\nconductance oscillations in atomically thin nanopores may originate from the\nmulti-ion interaction at the pore entry, particularly the electrostatic\nrepulsion of ions external to the pore by ions bound inside the pore. Our work\nadds a further understanding of ionic Coulomb blockade effect under extreme\nconfinement in atomically thin nanopores and paves the way for developing\nadvanced ionic machineries.",
        "positive": "Robust edge states induced by electron-phonon interaction in graphene\n  nanoribbons: The search of new means of generating and controlling topological states of\nmatter is at the front of many joint efforts, including bandgap engineering by\ndoping and light-induced topological states. Most of our understading, however,\nis based on a single particle picture. Topological states in systems including\ninteraction effects, such as electron-electron and electron-phonon, remain less\nexplored. By exploiting a non-perturbative and non-adiabatic picture, here we\nshow how the interaction between electrons and a coherent phonon mode can lead\nto a bandgap hosting edge states of topological origin. Further numerical\nsimulations witness the robustness of these states against different types of\ndisorder. Our results contribute to the search of topological states, in this\ncase in a minimal Fock space."
    },
    {
        "anchor": "Magnetization switching of FePt nanoparticle recording medium by\n  femtosecond laser pulses: Manipulation of magnetization with ultrashort laser pulses is promising for\ninformation storage device applications. The dynamic of the magnetization\nresponse depends on the energy transfer from the photons to the spins during\nthe initial laser excitation. A material of special interest for magnetic\nstorage is FePt nanoparticles , on which optical writing with optical angular\nmomentum was demonstrated recently by Lambert et al., although the mechanism\nremained unclear. Here we investigate experimentally and theoretically the\nall-optical switching of FePt nanoparticles. We show that the magnetization\nswitching is a stochastic process. We develop a complete multiscale model which\nallows us to optimize the number of laser shots needed to write the\nmagnetization of high anisotropy FePt nanoparticles in our experiments. We\nconclude that only angular momentum induced optically by the inverse Faraday\neffect will provide switching with one single femtosecond laser pulse.",
        "positive": "Abnormal temperature dependence of mobility in conjugated polymer /\n  nanocrystal composite: experiment and theory: Instead of normal non-Arrhenius relationship, the carrier mobility\n$ln({\\mu})$ v.s. $1/T^2$ showed abnormal dependence in an MEH-PPV / InP\nnanocrystal composite system that a critical temperature $(T_c)$ behavior is\nprominent in temperature range of 233 K to 333 K. Here, in the model of\nvariable range hopping theory, an analytical model is developed within a\nGaussian trap distribution, which is successfully implemented on that\nphenomenon. The results show that Tc becomes the transition temperature as long\nas trap-filling factor (FF) ~1, which means a transition point from Boltzmann\nto Fermi distribution. Furthermore, the model predicts an universal\nrelationship of $ln({\\mu})$ on $1/T^2$ determined by FF in any disordered\nsystem with traps."
    },
    {
        "anchor": "Spin in fractional quantum Hall systems: A system at filling factor 2/3 could be a candidate for a quantum Hall\nferromagnet at integer filling factor of composite fermions. Using exact\ndiagonalization with electrons on a torus we study the transition from the\nsinglet ground state to the polarized ground state at this filling and look for\nsignatures of quantum Hall ferromagnetism. Differences between the fractional\nand corresponding integer systems are emphasised. Most interestingly, we find\naround the transition a low excited half-polarized state which might become the\nground state in the thermodynamical limit. We study its structure and compare\nit to the singlet and polarized ground states. A new interpretation of the\nsinglet state is suggested and comparison of the filling factors 2/3 and 2/5 is\npresented. Adding magnetic inhomogeneities into the system we investigate the\nstability of all the three involved states and the tendency to build up domains\nlike in conventional ferromagnets.",
        "positive": "Domain wall dynamics in stepped magnetic nanowire with perpendicular\n  magnetic anisotropy: Micromagnetic simulation is carried out to investigate the current-driven\ndomain wall (DW) in a nanowire with perpendicular magnetic anisotropy (PMA). A\nstepped nanowire is proposed to pin DW and achieve high information storage\ncapacity based on multi-bit per cell scheme. The DW speed is found to increase\nfor thicker and narrower nanowires. For depinning DW from the stepped region,\nthe current density Jdep is investigated with emphasis on device geometry and\nmaterials intrinsic properties. The Jdep could be analytically determined as a\nfunction of the nanocontriction dimension and the thickness of the nanowire.\nFurthermore, Jdep is found to exponential dependent on the anisotropy energy\nand saturation magnetization, offering thus more flexibility in adjusting the\nwriting current for memory applications."
    },
    {
        "anchor": "Charge echo in a Cooper-pair box: A spin-echo-type technique is applied to an artificial two-level system that\nutilizes charge degree of freedom in a small superconducting electrode.\nGate-voltage pulses are used to produce the necessary pulse sequence in order\nto eliminate the inhomogeneity effect in the time-ensemble measurement and to\nobtain refocused echo signals. Comparison of the decay time of the observed\necho signal with estimated decoherence time suggests that low-frequency\nenergy-level fluctuations due to the 1/f charge noise dominate the dephasing in\nthe system.",
        "positive": "Observation of band narrowing and mode conversion in two-dimensional\n  binary magnonic crystal: We introduce a new type of binary magnonic crystal, where Ni$_{80}$Fe$_{20}$\nnanodots of two different sizes are diagonally connected forming a unit and\nthose units are arranged in a square lattice. The magnetization dynamics of the\nsample is measured by using time-resolved magneto-optical Kerr effect\nmicroscope with varying magnitude and in-plane orientation ($\\phi$) of the bias\nmagnetic field. Interestingly, at $\\phi=0^{\\circ}$, the spin-wave mode profiles\nshow frequency selective spatial localization of spin-wave power within the\narray. With the variation of $\\phi$ in the range $0^{\\circ}<\\phi\\leq\n45^{\\circ}$, we observe band narrowing due to localized to extended spin-wave\nmode conversion. Upon further increase of $\\phi$, the spin-wave modes slowly\nlose the extended nature and become fully localized again at 90$^{\\circ}$. We\nhave extensively demonstrated the role of magnetostatic stray field\ndistribution on the rotational symmetries obtained for the spin-wave modes.\nFrom micromagnetic simulations, we find that the dipole-exchange coupling\nbetween the nano-dots leads to remarkable modifications of the spin-wave mode\nprofiles when compared with arrays of individual small and large dots.\nNumerically, we also show that the physical connection between the nano-dots\nprovides more control points over the spin-wave propagation in the lattice at\ndifferent orientations of bias magnetic field. This new type of binary magnonic\ncrystal may find potential applications in magnonic devices such as spin-wave\nwaveguide, filter, coupler, and other on-chip microwave communication devices."
    },
    {
        "anchor": "Gauge fields from strain in graphene: We revise the tight binding approach to strained or curved graphene in the\npresence of external probes such as Photoemission or Scanning Tunneling\nMicroscopy experiments. We show that extra terms arise in the continuum limit\nof the tight binding Hamiltonian which can not be accounted for by changes in\nthe hopping parameters due to lattice deformations, encoded in the parameter\n\\beta. These material independent extra couplings are of the same order of\nmagnitude as the standard ones and have a geometric origin. They include\ncorrections to the position-dependent Fermi velocity and to a new vector field.\nWe show that the new vector field does not couple to electrons like a standard\ngauge field and that no ? \\beta-independent pseudomagnetic fields exist in\nstrained graphene.",
        "positive": "Density matrix Monte Carlo modeling of quantum cascade lasers: By including elements of the density matrix formalism, the semiclassical\nensemble Monte Carlo method for carrier transport is extended to incorporate\nincoherent tunneling, known to play an important role in quantum cascade lasers\n(QCLs). In particular, this effect dominates electron transport across thick\ninjection barriers, which are frequently used in terahertz QCL designs. A\nself-consistent model for quantum mechanical dephasing is implemented,\neliminating the need for empirical simulation parameters. Our modeling approach\nis validated against available experimental data for different types of\nterahertz QCL designs."
    },
    {
        "anchor": "A Predictive Analytic Model for High-Performance Tunneling-Field Effect\n  Transistors Approaching Non-Equilibrium Green's Function Simulations: A new compact modeling approach is presented which describes the full\ncurrent-voltage (I-V) characteristic of high-performance (aggressively\nscaled-down) tunneling field-effect-transistors (TFETs) based on homojunction\ndirect-bandgap semiconductors. The model is based on an analytic description of\ntwo key features, which capture the main physical phenomena related to TFETs:\n1) the potential profile from source to channel, and 2) the elliptic curvature\nof the complex bands in the bandgap region. It is proposed to use 1D Poisson's\nequations in the source and the channel to describe the potential profile in\nhomojunction TFETs. This allows to quantify the impact of source/drain doping\non device performance, an aspect usually ignored in TFET modeling but highly\nrelevant in ultra-scaled devices. The compact model is validated by comparison\nwith state-of-the-art quantum transport simulations using a 3D full band\natomistic approach based on Non-Equilibrium Green's Functions (NEGF). It is\nshown that the model reproduces with good accuracy the data obtained from the\nsimulations in all regions of operation: the on/off states and the n/p branches\nof conduction. This approach allows calculation of energy-dependent band-toband\ntunneling currents in TFETs, a feature that allows gaining deep insights into\nthe underlying device physics. The simplicity and accuracy of the approach\nprovides a powerful tool to explore in a quantitatively manner how a wide\nvariety of parameters (material-, size- and/or geometrydependent) impact the\nTFET performance under any bias conditions. The proposed model presents thus a\npractical complement to computationally expensive simulations such as the 3D\nNEGF approach.",
        "positive": "Geometric characterization of anomalous Landau levels of isolated flat\n  bands: According to the Onsager's semiclassical quantization rule, the Landau levels\nof a band are bounded by its upper and lower band edges at zero magnetic field.\nHowever, there are two notable systems where the Landau level spectra violate\nthis expectation, including topological bands and flat bands with singular band\ncrossings, whose wave functions possess some singularities. Here, we introduce\na distinct class of flat band systems where anomalous Landau level spreading\n(LLS) appears outside the zero-field energy bounds, although the relevant wave\nfunction is nonsingular. The anomalous LLS of isolated flat bands are governed\nby the cross-gap Berry connection that measures the wave-function geometry of\nmulti bands. We also find that symmetry puts strong constraints on the LLS of\nflat bands. Our work demonstrates that an isolated flat band is an ideal system\nfor studying the fundamental role of wave-function geometry in describing\nmagnetic responses of solids."
    },
    {
        "anchor": "Shadow epitaxy for in-situ growth of generic\n  semiconductor/superconductor devices: Uniform, defect-free crystal interfaces and surfaces are crucial ingredients\nfor realizing high-performance nanoscale devices. A pertinent example is that\nadvances in gate-tunable and topological superconductivity using\nsemiconductor/superconductor electronic devices are currently built on the hard\nproximity-induced superconducting gap obtained from epitaxial indium\narsenide/aluminium heterostructures. Fabrication of devices requires selective\netch processes; these exist only for InAs/Al hybrids, precluding the use of\nother, potentially superior material combinations. We present a crystal growth\nplatform -- based on three-dimensional structuring of growth substrates --\nwhich enables synthesis of semiconductor nanowire hybrids with in-situ\npatterned superconductor shells. This platform eliminates the need for etching,\nthereby enabling full freedom in choice of hybrid constituents. We realise and\ncharacterise all the most frequently used architectures in superconducting\nhybrid devices, finding increased yield and electrostatic stability compared to\netched devices, along with evidence of ballistic superconductivity. In addition\nto aluminium, we present hybrid devices based on tantalum, niobium and\nvanadium.\n  This is the submitted version of the manuscript. The accepted, peer reviewed\nversion is available from Advanced Materials:\nhttp://doi.org/10.1002/adma.201908411\n  Previous title: Shadow lithography for in-situ growth of generic\nsemiconductor/superconductor devices",
        "positive": "Two-step splitting the expandable graphite for few-layer graphene: Few-layer graphene sheets are prepared by splitting the expanded graphites\nusing a high-power sonication. Atomic-level quantitative scanning transmission\nelectron microscopy (Q-STEM) is employed to carry out the efficient layer\nstatisticsm, enabling global optimization of the experimental conditions. A\ntwo-step splitting mechanism is thus revealed, in which the mean layer number\nwas firstly reduced to less than 20 by heating to 1100{\\deg}C and then tuned to\nthe few-layer region by a 5-minute 104W/litre sonication. Raman spectroscopic\nanalysis confirms the above mechanism and demonstrates that the sheets are\nlargely free of defects and oxides."
    },
    {
        "anchor": "Effects of pressure on suspended micromechanical membrane arrays: The effects of pressure on micromechanical air-filled cavities made by a pair\nof suspended, parallel silicon nitride membranes are investigated in the free\nmolecular and quasi-molecular regimes. Variations of the fundamental drummode\nmechanical resonant frequencies and damping with air pressure are determined by\nmeans of optical interferometry. A kinetic damping linear friction force and a\npositive resonant frequency shift due to the compression of the fluid between\nthe membranes are observed to be proportional with pressure in the range\n0.01-10 mbars. For resonators with near-degenerate modes hybridization of the\nmodes due to this squeeze film effect is also observed and well accounted for\nby a simple spring-coupled oscillator model.",
        "positive": "Unique electronic and optical properties of stacking-modulated bilayer\n  graphene under external magnetic fields: This study delves into the magneto-electronic and magneto-optical properties\nof stacking-modulated bilayer graphene. By manipulating domain walls (DWs)\nacross AB-BA domains periodically, we unveil oscillatory Landau subbands and\nthe associated optical excitations. The DWs act as periodic potentials,\nyielding fascinating 1D spectral features. Our exploration reveals 1D phenomena\nlocalized to Bernal stacking, DW regions, and stacking boundaries, highlighting\nthe intriguing formation of Landau state quantization influenced by the\ncommensuration between the magnetic length and the system. The stable quantized\nlocalization within different regions leads to the emergence of unconventional\nquantized subbands. This study provides valuable insights into the essential\nproperties of stacking-modulated bilayer graphene."
    },
    {
        "anchor": "Energy Spectra of Few-Electron Quantum Dots: We present the renormalized perturbation series for the energy spectrum of\nthe parabolic quantum dot with 2 -- 5 electrons considering ground and the\nlowest excited states. The proper classification of asymptotic energy levels is\nperformed and behaviour of energy levels from quantum to semiclassical regime\nis traced. Comparison between the present results and those of exact numerical\nHamiltonian diagonalization shows a fair accuracy of the proposed method over\nthe whole range of the electron-electron coupling constant and magnetic field\nvalues. The obtained results indicate that increasing of the number of\nelectrons in a dot leads to more classic behaviour of the system.",
        "positive": "Stark effect on the exciton complexes of individual quantum dots: The emission spectrum of exciton complexes formed in individual\nself-assembled quantum dots (QDs) embedded into a p-n junction is theoretically\nstudied using an effective mass model. We calculate the particle Coulomb\ninteractions, eletron-hole overlaps and transition energies of exciton\ncomplexes for the different strength and direction of electric field. Both\nredshifts and blueshifts are observed in exciton, trions and biexciton. The\nStark effect may be applied to manipulate the spontaneous emission rate of\nindividual QDs embedded in microcavities."
    },
    {
        "anchor": "Proximal quantum control of spin and spin ensemble with highly localized\n  control field from skyrmions: Selective control of individual spin qubits is needed for scalable quantum\ncomputing based on spin states. Achieving high-fidelity in both single and\ntwo-qubit gates, essential components of universal quantum computers,\nnecessitates highly localized control fields. These fields must be capable of\naddressing specific spin qubits while minimizing gate errors and cross-talk in\nadjacent qubits. Overcoming the challenge of generating a localized\nradio-frequency magnetic field, in the absence of elementary magnetic\nmonopoles, we introduce a technique that combines divergent and convergent\nnanoscale magnetic skyrmions. This approach produces a precise control field\nthat manipulates spin qubits with high fidelity. We propose the use of 2D\nskyrmions, which are 2D analogues of 3D hedgehog structures. The latter are\nemergent magnetic monopoles, but difficult to fabricate. The 2D skyrmions, on\nthe other hand, can be fabricated using standard semiconductor foundry\nprocesses. Our comparative analysis of the density matrix evolution and gate\nfidelities in scenarios involving proximal skyrmions and nanomagnets indicates\npotential gate fidelities surpassing 99.95% for {\\pi}/2-gates and 99.90% for\n{\\pi}-gates. Notably, the skyrmion configuration generates a significantly\nlower field on neighboring spin qubits, i.e. 15 times smaller field on a\nneighboring qubit compared to nanomagnets that produces the same field at the\ncontrolled qubit, making it a more suitable candidate for scalable quantum\ncontrol architectures by reducing disturbances in adjacent qubits.",
        "positive": "Signature of nodal topology in nonlinear quantum transport across\n  junctions in Weyl and multi-Weyl semimetals: We investigate quantum transport through a rectangular potential barrier in\nWeyl semimetals (WSMs) and multi-Weyl semimetals (MSMs), within the framework\nof Landauer-B\\\"uttiker formalism. Our study uncovers the role of nodal topology\nimprinted in the electric current and the shot noise. We find that, in contrast\nto the finite odd-order conductance and noise power, the even-order\ncontributions vanish at the nodes. Additionally, depending on the topological\ncharge ($J$), the linear conductance ($G_1$) scales with the Fermi energy\n($E_F$) as $G_1^{E_F>U}\\propto E_F^{2/J}$. We demonstrate that the\n$E_F$-dependence of the second-order conductance and shot noise power could\nquite remarkably distinguish an MSM from a WSM depending on the band topology,\nand may induce several smoking gun experiments in nanostructures made out of\nWSMs and MSMs. Analyzing shot noise and Fano factor, we show that the transport\nacross the rectangular barrier follows the sub-Poissonian statistics.\nInterestingly, we obtain universal values of Fano factor at the nodes unique to\ntheir topological charges. The universality for a fixed $J$, however, indicates\nthat only a fixed number of open channels participate in the transport through\nevanescent waves at the nodes. The proposed results can serve as a potential\ndiagnostic tool to identify different topological systems in experiments."
    },
    {
        "anchor": "Resonance Fluorescence in Transport through Quantum Dots: Noise\n  Properties: We study a two-level quantum dot embedded in a phonon bath and irradiated by\na time-dependent ac field and develope a method that allows us to extract\nsimultaneously the full counting statistics of the electronic tunneling and\nrelaxation (by phononic emission) events as well as their correlation. We find\nthat the quantum noise of both the transmitted electrons and the emitted\nphonons can be controlled by the manipulation of external parameters such as\nthe driving field intensity or the bias voltage.",
        "positive": "Magnetic properties of metal-organic coordination networks based on 3d\n  transition metal atoms: The magnetic anisotropy and exchange coupling between spins localized at the\npositions of 3d transition metal atoms forming two-dimensional metal-organic\ncoordination networks (MOCNs) grown on the Au(111) metal surface are studied.\nIn particular, we consider MOCNs made of Ni or Mn metal centers linked by TCNQ\n(7,7,8,8-tetracyanoquinodimethane) organic ligands, which form rectangular\nnetworks with 1:1 stoichiometry. Based on the analysis of X-ray magnetic\ncircular dichroism (XMCD) data taken at T= 2.5 K, we find that Ni atoms in the\nNi-TCNQ MOCNs are coupled ferromagnetically and do not show any significant\nmagnetic anisotropy, while Mn atoms in the Mn-TCNQ MOCNs are coupled\nantiferromagnetically and do show a weak magnetic anisotropy with\nin-planemagnetization. We explain these observations using both\namodelHamiltonian based on mean-fieldWeiss theory and density functional theory\ncalculations that include spin-orbit coupling. Our main conclusion is that the\nantiferromagnetic coupling between Mn spins and the in-plane magnetization of\nthe Mn spins can be explained neglecting effects due to the presence of the\nAu(111) surface, while for Ni-TCNQ the metal surface plays a role in\ndetermining the absence of magnetic anisotropy in the system."
    },
    {
        "anchor": "Exchange interactions and full magnetization process of multispin\n  nanoclaster Mn4: Full magnetization process of magnetic nanocluster Mn4, including all its\nactual multiplets, is theoretically investigated. The formulas needed to\ndetermine the exchange constants of cluster Mn4 from experimental data are\nobtained. It is shown that quantum jumps of magnetization of this nanocluster\nare in area of megagauss magnetic fields. Remarkable feature of considered\nnanocluster Mn4 differing it from other multispin molecules is that its\nexchange spin Hamiltonian supposes exact diagonalization. This provides a\nreliable basis for comparison of theoretical predictions with experimental data\nand is important for development of new experimental techniques of high-spin\nmolecule research.",
        "positive": "Decay of semiclassical massless Dirac fermions from integrable and\n  chaotic cavities: Conventional microlasing of electromagnetic waves requires (1) a high $Q$\ncavity and (2) a mechanism for directional emission. Previous theoretical and\nexperimental work demonstrated that the two requirements can be met with\ndeformed dielectric cavities that generate chaotic ray dynamics. Is it possible\nfor a massless Dirac spinor wave in graphene or its photonic counterpart to\nexhibit a similar behavior? Intuitively, because of the absence of\nbackscattering of associated massless spin-1/2 particles and Klein tunneling,\nconfining the wave in a cavity for a long time seems not feasible. Deforming\nthe cavity to generate classical chaos would make confinement even more\ndifficult. Investigating the decay of a spin-1/2 wave from a scalar potential\nbarrier defined cavity characterized by an effective refractive index $n$ that\ndepends on the applied potential and the particle energy, we uncover the\nstriking existence of an interval of the refractive index in which the average\nlifetime of the massless spin-1/2 wave in the cavity can be as high as that of\nthe electromagnetic wave, for both integrable and chaotic cavities. We also\nfind scaling laws for the ratio between the mean escape time associated with\nelectromagnetic waves and that with massless spin-1/2 particles versus the\nindex outside of this interval. The scaling laws hold regardless of the nature\nof the classical dynamics. All the results are verified numerically. The\nfindings provide insights into the emergent field of Dirac electron optics and\nhave potential applications in developing unconventional electronics using 2D\nDirac materials."
    },
    {
        "anchor": "The mesoscopic magnetron as an open quantum system: Motivated by the emergence of materials with mean free paths on the order of\nmicrons, we propose a novel class of solid state radiation sources based on\nreimplementing classical vacuum tube designs in semiconductors. Using materials\nwith small effective masses, these devices should be able to access the\nterahertz range. We analyze the DC and AC operation of the simplest such\ndevice, the cylindrical diode magnetron, using effective quantum models. By\ntreating the magnetron as an open quantum system, we show that it continues to\noperate as a radiation source even if its diameter is only a few tens of\nmagnetic lengths.",
        "positive": "Conditions for fully gapped topological superconductivity in topological\n  insulator nanowires: Among the different platforms to engineer Majorana fermions in\none-dimensional topological superconductors, topological insulator nanowires\nremain a promising option. Threading an odd number of flux quanta through these\nwires induces an odd number of surface channels, which can then be gapped with\nproximity induced pairing. Because of the flux and depending on energetics, the\nphase of this surface pairing may or may not wind around the wire in the form\nof a vortex. Here we show that for wires with discrete rotational symmetry,\nthis vortex is necessary to produce a fully gapped topological superconductor\nwith localized Majorana end states. Without a vortex the proximitized wire\nremains gapless, and it is only if the symmetry is broken by disorder that a\ngap develops, which is much smaller than the one obtained with a vortex. These\nresults are explained with the help of a continuum model and validated\nnumerically with a tight binding model, and highlight the benefit of a vortex\nfor reliable use of Majorana fermions in this platform."
    },
    {
        "anchor": "Non-equilibrium theory for strongly coupled quantum dot with arbitrary\n  on-site correlation strength: An analytical expression for the current through a single level quantum dot\nfor arbitrary strength of the on-site electron-electron interaction is derived\nbeyond standard mean-field theory. By describing the localised states in terms\nof many-body operators, the employed diagrammatic technique for strong coupling\nenables inclusion of electron correlation effects into the description of the\nlocal dynamics, which provides transport properties that are consistent with\nrecent experimental data.",
        "positive": "Thermal transport in semiconductor nanostructures, graphene and related\n  two-dimensional materials: We review experimental and theoretical results on thermal transport in\nsemiconductor nanostructures (multilayer thin films, core/shell and segmented\nnanowires), single- and few-layer graphene, hexagonal boron nitride, molybdenum\ndisulfide and black phosphorus. Different possibilities of phonon engineering\nfor optimization of electrical and heat conductions are discussed. The role of\nthe phonon energy spectra modification on the thermal conductivity in\nsemiconductor nanostructures is revealed. The dependence of thermal\nconductivity in graphene and related two-dimensional (2D) materials on\ntemperature, flake size, defect concentration, edge roughness and strain is\nanalyzed."
    },
    {
        "anchor": "Phonon-bottleneck enhanced exciton emission in 2D perovskites: Layered halide perovskites exhibit remarkable optoelectronic properties and\ntechnological promise, driven by strongly bound excitons. The interplay of\nspin-orbit and exchange coupling creates a rich excitonic landscape,\ndetermining their optical signatures and exciton dynamics. Despite the dark\nexcitonic ground state, surprisingly efficient emission from higher-energy\nbright states has puzzled the scientific community, sparking debates on\nrelaxation mechanisms. Combining low-temperature magneto-optical measurements\nwith sophisticated many-particle theory, we elucidate the origin of the bright\nexciton emission in perovskites by tracking the thermalization of dark and\nbright excitons under a magnetic field. We clearly attribute the unexpectedly\nhigh emission to a pronounced phonon-bottleneck effect, considerably slowing\ndown the relaxation towards the energetically lowest dark states. We\ndemonstrate that this bottleneck can be tuned by manipulating the bright-dark\nenergy splitting and optical phonon energies, offering valuable insights and\nstrategies for controlling exciton emission in layered perovskite materials\nthat is crucial for optoelectronics applications.",
        "positive": "Microscopic theory of Raman scattering for the rotational organic cation\n  in metal halide perovskites: A gap exists in microscopic understanding the dynamic properties of the\nrotational organic cation (ROC) in the inorganic framework of the metal halide\nperovskites (MHP) to date. Herein, we develop a microscopic theory of Raman\nscattering for the ROC in MHP based on the angular momentum of a ROC exchanging\nwith that of the photon and phonon. We systematically present the selection\nrules for the angular momentum transfer among three lowest rotational levels.\nWe find that the phonon angular momentum that arising from the inorganic\nframework and its specific values could be directly manifested by Stokes (or\nanti-Stokes) shift. Moreover, the initial orientation of the ROC and its\npreferentially rotational directions could be judged in Raman spectra. This\nstudy lays the theoretical foundation for the high-precision resolution and\nmanipulation of molecular rotation immersed in many-body environment by Raman\ntechnique."
    },
    {
        "anchor": "Ab-initio GMR and current-induced torques in Au/Cr multilayers: We report on an {\\em ab-initio} study of giant magnetoresistance (GMR) and\ncurrent-induced-torques (CITs) in Cr/Au multilayers that is based on\nnon-equilibrium Green's functions and spin density functional theory. We find\nsubstantial GMR due primarily to a spin-dependent resonance centered at the\nCr/Au interface and predict that the CITs are strong enough to switch the\nantiferromagnetic order parameter at current-densities $\\sim 100$ times smaller\nthan typical ferromagnetic metal circuit switching densities.",
        "positive": "Nanoscale imaging of current density with a single-spin magnetometer: Charge transport in nanostructures and thin films is fundamental to many\nphenomena and processes in science and technology, ranging from quantum effects\nand electronic correlations in mesoscopic physics, to integrated charge- or\nspin-based electronic circuits, to photoactive layers in energy research.\nDirect visualization of the charge flow in such structures is challenging due\nto their nanometer size and the itinerant nature of currents. In this work, we\ndemonstrate non-invasive magnetic imaging of current density in two-dimensional\nconductor networks including metallic nanowires and carbon nanotubes. Our\nsensor is the electronic spin of a diamond nitrogen-vacancy center attached to\na scanning tip. Using a differential measurement technique, we detect DC\ncurrents down to a few uA above a baseline current density of 2e4 A/cm2.\nReconstructed images have a spatial resolution of typically 50 nm, with a\nbest-effort value of 22 nm. Current density imaging offers a new route for\nstudying electronic transport and conductance variations in two-dimensional\nmaterials and devices, with many exciting applications in condensed matter\nphysics."
    },
    {
        "anchor": "Resonant Thermoelectric Nanophotonics: Photodetectors are typically based on photocurrent generation from\nelectron-hole pairs in semiconductor structures and on bolometry for\nwavelengths that are below bandgap absorption. In both cases, resonant\nplasmonic and nanophotonic structures have been successfully used to enhance\nperformance. In this work, we demonstrate subwavelength thermoelectric\nnanostructures designed for resonant spectrally selective absorption, which\ncreates large enough localized temperature gradients to generate easily\nmeasureable thermoelectric voltages. We show that such structures are tunable\nand are capable of highly wavelength specific detection, with an input power\nresponsivity of up to 119 V/W (referenced to incident illumination), and\nresponse times of nearly 3 kHz, by combining resonant absorption and\nthermoelectric junctions within a single structure, yielding a\nbandgap-independent photodetection mechanism. We report results for both\nresonant nanophotonic bismuth telluride-antimony telluride structures and\nchromel-alumel structures as examples of a broad class of nanophotonic\nthermoelectric structures useful for fast, low-cost and robust optoelectronic\napplications such as non-bandgap-limited hyperspectral and broad-band\nphotodetectors.",
        "positive": "Spin-orbit torque switching of N\u00e9el order in two-dimensional CrI$_3$: Spin-orbit torque enables electrical control of the magnetic state of\nferromagnets or antiferromagnets. In this work we consider the spin-orbit\ntorque in the 2-d Van der Waals antiferromagnetic bilayer CrI$_3$, in the\n$n$-doped regime. In the purely antiferromagnetic state, two individually\ninversion-symmetry broken layers of CrI$_3$ form inversion partners, like the\nwell-studied CuMnAs and Mn$_2$Au. However, the exchange and anisotropy energies\nare similar in magnitude, unlike previously studied antiferromagnets, which\nleads to qualitatively different behaviors in this material. Using a\ncombination of first-principles calculations of the spin-orbit torque and an\nanalysis of the ensuing spin dynamics, we show that the deterministic\nelectrical switching of the N\\'eel vector is the result of dampinglike\nspin-orbit torque, which is staggered on the magnetic sublattices."
    },
    {
        "anchor": "Carrier mean free path and temperature imbalance in mesoscopic wires: Non-coherent electronic transport in metallic nanowires exhibits different\ncarrier temperatures for the non-equilibrium forward and backward populations\nin the presence of electric fields. Depending on the mean free path that\ncharacterizes inter-branch carrier backscattering transport regimes vary\nbetween the ballistic and diffusive limits. In particular, we show that the\nsimultaneous measurements of the electrical characteristics and the carrier\ndistribution function offer a direct way to extract the carrier mean free path\neven when it is comparable to the conductor length. Our model is in good\nagreement with the experimental work on copper nanowires by Pothier {\\it et\nal.} [Phys. Rev. Lett. {\\bf 79}, 3490 (1997)] and provides an elegant\ninterpretation of the inhomogeneous thermal broadening observed in the local\ncarrier distribution function as well as its scaling with external bias.",
        "positive": "Persistent currents in carbon nanotubes: Persistent currents driven by a static magnetic flux parallel to the carbon\nnanotube axis are investigated. Owing to the hexagonal symmetry of graphene the\nFermi contour expected for a 2D-lattice reduces to two points. However the\nelectron or hole doping shifts the Fermi energy upwards or downwards and as a\nresult, the shape of the Fermi surface changes. Such a hole doping leading to\nthe Fermi level shift of (more or less) 1eV has been recently observed\nexperimentally. In this paper we show that the shift of the Fermi energy\nchanges dramatically the persistent currents and discuss the electronic\nstructure and possible currents for zigzag as well as armchair nanotubes."
    },
    {
        "anchor": "The next nearest neighbor effect on the 2D materials properties: In this work, the effect of introducing next nearest neighbor (NNN) hopping\nto the 2D materials was studied using the graphene 2D honeycomb two sublattice\nas an example. It is found that introducing NNN to the 2D materials removes the\nsymmetry around the Fermi level and shifts it, at a small value of NNN hopping.\nThis effect increases with increasing NNN hopping. If the NNN hopping becomes\ncompetitive with nearest neighbor (NN) hopping, the dispersion relations of the\n2D materials changes completely from NN hopping dispersion relations. The\nresults show that the 2D material sensitivity for NNN hopping effect is much\nlarger in the 2D honeycomb lattice than 2D square lattice. This is due to the\nfact that the number of NNN sites is equal to six, which is the double of NN\nsites in the 2D honeycomb lattice. Meanwhile, the number of NNN sites is equal\nto four which is equal to NN sites in 2D square lattice. We therefore conclude\nthat by changing the ratio between NNN and NN sites in the 2D lattice one can\ntune the sensitivity for NNN hopping effects.",
        "positive": "Effect of interactions and non-uniform magnetic states on the\n  magnetization reversal of iron nanowire arrays: Ordered ferromagnetic nanowire arrays are widely studied due to the diversity\nof possible applications. However, there is still no complete understanding of\nthe relation between the array's parameters and its magnetic behavior. The\neffect of vortex states on the magnetization reversal of large-diameter\nnanowires is of particular interest. Here, we compare analytical and\nmicromagnetic models with experimental results for three arrays of iron\nnanowires with diameters of 33, 52 and 70 nm in order to find the balance\nbetween the number of approximations and resources used for the calculations.\nThe influence of the vortex states and the effect of interwire interactions on\nthe remagnetization curves is discussed. It has been found that 7 nanowires\ntreated by a mean field model are able to reproduce well the reversal behaviour\nof the whole array in the case of large diameter nanowires. Vortex states tend\nto decrease the influence of the structural inhomogeneities on reversal process\nand thus lead to the increased predictability of the system."
    },
    {
        "anchor": "Charge-noise resilience of two-electron quantum dots in Si/SiGe\n  heterostructures: The valley degree of freedom presents challenges and opportunities for\nsilicon spin qubits. An important consideration for singlet-triplet states is\nthe presence of two distinct triplets, comprised of valley vs. orbital\nexcitations. Here we show that both of these triplets are present in the\ntypical operating regime, but that only the valley-excited triplet offers\nintrinsic protection against charge noise. We further show that this protection\narises naturally in dots with stronger confinement. These results reveal an\ninherent advantage for silicon-based multi-electron qubits.",
        "positive": "Non-adiabadic charge pumping in a hybrid SET transistor: We study theoretically current quantization in the charge turnstile based on\nthe hybrid (SINIS or NISIN) SET transistor. The quantization accuracy is\nlimited by either Andreev reflection or by Cooper pair - electron cotunneling.\nThe rates of these processes are calculated in the ``above-the-threshold''\nregime when they compete directly with the lowest-order tunneling. We show that\nby shaping the ac gate voltage driving the turnstile, it should be possible to\nachieve the metrological accuracy of $10^{-8}$, while maintaining the absolute\nvalue of the quantized current on the order of 30 pA, just by one turnstile\nwith realistic parameters using aluminium as superconductor."
    },
    {
        "anchor": "Berry phase in graphene: a semiclassical perspective: We derive a semiclassical expression for the Green's function in graphene, in\nwhich the presence of a semiclassical phase is made apparent. The relationship\nbetween this semiclassical phase and the adiabatic Berry phase, usually\nreferred to in this context, is discussed. These phases coincide for the\nperfectly linear Dirac dispersion relation. They differ however when a gap is\nopened at the Dirac point. We furthermore present several applications of our\nsemiclassical formalism. In particular we provide, for various configurations,\na semiclassical derivation of the electron's Landau levels, illustrating the\nrole of the semiclassical ``Berry-like'' phase",
        "positive": "Long wavelength spatial oscillations of high frequency current noise in\n  1D electron systems: Finite frequency current noise is studied theoretically for a 1D electron\nsystem in presence of a scatterer. In contrast to zero frequency shot noise,\nfinite frequency noise shows spatial oscillations at high frequencies with\nwavelength $\\pi v_F/\\omega$. Band curvature leads to a decay of the amplitude\nof the noise oscillations as one moves away from the scatterer, superimposed by\na beat. Furthermore, Coulomb interaction reduces the amplitude and modifies the\nwavelength of the oscillations, which we inspect in the framework of the\nLuttinger liquid (LL) model. The oscillatory noise contributions are only\nsuppressed altogether when the LL interaction parameter $g \\to 0$."
    },
    {
        "anchor": "Antiferromagnetism in hexagonal graphene structures: Rings vs dots: The mean-field Hubbard model is used to investigate the formation of the\nantiferromagnetic phase in hexagonal graphene rings with inner zigzag edges.\nThe outer edge of the ring was taken to be either zigzag or armchair, and we\nfound that both types of structures can have a larger antiferromagnetic\ninteraction as compared with hexagonal dots. This difference could be partially\nascribed to the larger number of zigzag edges per unit area in rings than in\ndots. Furthermore, edge states localized on the inner ring edge are found to\nhybridize differently than the edge states of dots, which results in important\ndifferences in the magnetism of graphene rings and dots. The largest staggered\nmagnetization is found when the outer edge has a zigzag shape. However, narrow\nrings with armchair outer edge are found to have larger staggered magnetization\nthan zigzag hexagons. The edge defects are shown to have the least effect on\nmagnetization when the outer ring edge is armchair shaped.",
        "positive": "High Bias Voltage Transport in Metallic Single-walled Carbon Nanotubes\n  under Axial Stress: We calculate the current-voltage characteristic of a homogeneously strained\nmetallic carbon nanotube adsorbed on a substrate. The strain generates a gap in\nthe energy spectrum leading to a reduction of the current. In the elastic\nregime, the current-voltage characteristic shows a large negative differential\nconductance at bias voltages of around $ \\gtrsim 0.17 $V. We discuss the\nimplications for the current in the superelongated regime."
    },
    {
        "anchor": "Measurement of Filling-Factor-Dependent Magnetophonon Resonances in\n  Graphene Using Raman Spectroscopy: We perform polarization-resolved Raman spectroscopy on graphene in magnetic\nfields up to 45T. This reveals a filling-factor-dependent, multi-component\nanticrossing structure of the Raman G peak, resulting from magnetophonon\nresonances between magnetoexcitons and E$_{2g}$ phonons. This is explained with\na model of Raman scattering taking into account the effects of spatially\ninhomogeneous carrier densities and strain. Random fluctuations of\nstrain-induced pseudo-magnetic fields lead to increased scattering intensity\ninside the anti-crossing gap, consistent with the experiment.",
        "positive": "The Rashba Hamiltonian and electron transport: The Rashba Hamiltonian describes the splitting of the conduction band as a\nresult of spin-orbit coupling in the presence of an external field and is\ncommonly used to model the electronic structure of confined narrow-gap\nsemiconductors. Due to the mixing of spin states some care has to be exercised\nin the calculation of transport properties. We derive the velocity operator for\nthe Rashba-split conduction band and demonstrate that the transmission of an\ninterface between a ferromagnet and a Rashba-split semiconductor does not\ndepend on the magnetization direction, in contrast with previous assertions in\nthe literature."
    },
    {
        "anchor": "Trial wave functions with long-range Coulomb correlations for\n  two-dimensional N-electron systems in high magnetic fields: A new class of analytic wave functions is derived for two dimensional\nN-electron (2 <= N < infinity) systems in high magnetic fields. These functions\nare constructed through breaking (at the Hartree-Fock level) and subsequent\nrestoration (via post-Hartree-Fock methods) of the circular symmetry. They are\nsuitable for describing long-range Coulomb correlations, while the Laughlin and\ncomposite-fermion functions describe Jastrow correlations associated with a\nshort-range repulsion. Underlying our approach is a\ncollectively-rotating-electron-molecule picture, yielding for all N an\noscillatory radial electron density.",
        "positive": "Site-Specific Contributions to the Band Inversion in a Topological\n  Crystalline Insulator: In a topological crystalline insulator (TCI) the inversion of the bulk\nvalence and conduction bands is a necessary condition to observe surface\nmetallic states. Solid solutions of Pb$_{1-x}$Sn$_x$Te have been shown to be\nTCI, where band inversion occurs as a result of the band gap evolution upon\nalloying with Sn. The origins of this band inversion remain unclear. Herein the\nrole of Sn insertion into the PbTe matrix is investigated for the $p$-type\nPb$_{1-x}$Sn$_x$Te series with $x$ = 0, 0.35, 0.60, and 1.00 via nuclear\nmagnetic resonance (NMR) and transport measurements. $^{207}$Pb, $^{119}$Sn,\nand $^{125}$Te line shapes, spin-lattice relaxation rates, and Knight shifts\nprovide site-specific characterization of the electronic band structure. This\nprobe of the electronic band structure shows that the band inversion is\nunaffected by lattice distortions but related to spatial electronic\ninhomogeneities formed by Sn incorporation into the PbTe matrix. Strong\nrelativistic effects are found to be responsible for the band inversion,\nregardless of carrier type and concentration, suggesting a novel interpretation\nof the band gap evolution with composition. The temperature dependences of the\nNMR parameters reveal a negative temperature coefficient of the direct gap for\nSnTe and positive coefficient for PbTe."
    },
    {
        "anchor": "On the extreme nonlinear optics of graphene nanoribbons in the strong\n  coherent radiation fields: The generation of high-order harmonics in quasi-one-dimensional graphene\nnanoribbons (GNRs) initiated by intense coherent radiation is investigated. A\nmicroscopic theory describing the extreme nonlinear optical response of GNRs is\ndeveloped. The closed set of differential equations for the single-particle\ndensity matrix at the GNR-strong laser field multiphoton interaction is solved\nnumerically. The obtained solutions indicate the significance of the bandgap\nwidth and Fermi energy level on the high-order harmonic generation process in\nGNRs.",
        "positive": "An artificial atom locked to natural atoms: Single-photon sources that emit photons at the same energy play a key role in\nthe emerging concepts of quantum information, such as entanglement swapping,\nquantum teleportation and quantum networks. They can be realized in a variety\nof systems, where semiconductor quantum dots, or 'artificial atoms', are\narguably among the most attractive. However, unlike 'natural atoms', no two\nartificial atoms are alike. This peculiarity is a serious hurdle for quantum\ninformation applications that require photonic quantum states with identical\nenergies. Here we demonstrate a single artificial atom that generates photons\nwith an absolute energy that is locked to an optical transition in a natural\natom. Furthermore, we show that our system is robust and immune to drifts and\nfluctuations in the environment of the emitter. Our demonstration is crucial\nfor realization of a large number of universally-indistinguishable solid-state\nsystems at arbitrary remote locations, where frequency-locked artificial atoms\nmight become fundamental ingredients."
    },
    {
        "anchor": "Pseudomagnetic fields in graphene nanobubbles of constrained geometry: A\n  molecular dynamics study: Analysis of the strain-induced pseudomagnetic fields (PMFs) generated in\ngraphene nanobulges under three different substrate scenarios shows that, in\naddition to the shape, the graphene-substrate interaction can crucially\ndetermine the overall distribution and magnitude of strain and those fields, in\nand outside the bulge. We utilize a combination of classical molecular\ndynamics, continuum mechanics, and tight-binding electronic structure\ncalculations as an unbiased means of studying pressure-induced deformations and\nthe resulting PMF in graphene nanobubbles of various geometries. The interplay\namong substrate aperture geometry, lattice orientation, internal gas pressure,\nand substrate type is analyzed in view of strain-engineered graphene\nnanostructures capable of confining and/or guiding electrons at low energies.\nExcept in highly anisotropic geometries, the magnitude of the PMF is generally\nsignificant only near the boundaries of the aperture and rapidly decays towards\nthe center because under gas pressure at the scales considered here there is\nconsiderable bending at the edges and the central region displays nearly\nisotropic strain. When the deflection lead to sharp bends at the edges,\ncurvature and the tilting of the $p_z$ orbitals cannot be ignored and\ncontributes substantially to the total field. The strong and localized nature\nof the PMF at the boundaries and its polarity-changing profile can be exploited\nto trap electrons inside the bubble or of guiding them in channel-like\ngeometries defined by edges. However, we establish that slippage of graphene\nagainst the substrate is an important factor in determining the degree of\nconcentration of PMFs in or around the bulge since it can lead to considerable\nsoftening of the strain gradients there. The nature of the substrate emerges\nthus as a decisive factor determining the effectiveness of nanoscale PMFs\ntailoring in graphene.",
        "positive": "Role of Quantum Confinement in Luminescence Efficiency of Group IV\n  Nanostructures: Experimental results obtained previously for the photoluminescence efficiency\n(PL$_{eff}$) of Ge quantum dots (QDs) are theoretically studied. A\n$\\log$-$\\log$ plot of PL$_{eff}$ versus QD diameter ($D$) resulted in an\nidentical slope for each Ge QD sample only when $E_{G}\\sim (D^2+D)^{-1}$. We\nidentified that above $D\\approx$ 6.2 nm: $E_{G}\\sim D^{-1}$ due to a changing\neffective mass (EM), while below $D\\approx$ 4.6 nm: $E_{G}\\sim D^{-2}$ due to\nelectron/ hole confinement. We propose that as the QD size is initially\nreduced, the EM is reduced, which increases the Bohr radius and interface\nscattering until eventually pure quantum confinement effects dominate at small\n$D$."
    },
    {
        "anchor": "From tunneling to contact: Inelastic signals in an atomic gold junction: The evolution of electron conductance in the presence of inelastic effects is\nstudied as an atomic gold contact is formed evolving from a low-conductance\nregime (tunneling) to a high-conductance regime (contact). In order to\ncharacterize each regime, we perform density functional theory (DFT)\ncalculations to study the geometric and electronic structures, together with\nthe strength of the atomic bonds and the associated vibrational frequencies.\nThe conductance is calculated by first evaluating the transmission of electrons\nthrough the system, and secondly by calculating the conductance change due to\nthe excitation of vibrations. As found in previous studies [Paulsson et al.,\nPhys. Rev. B. 72, 201101(R) (2005)] the change in conductance due to inelastic\neffects permits to characterize the crossover from tunneling to contact. The\nmost notorious effect being the crossover from an increase in conductance in\nthe tunneling regime to a decrease in conductance in the contact regime when\nthe bias voltage matches a vibrational threshold. Our DFT-based calculations\nactually show that the effect of vibrational modes in electron conductance is\nrather complex, in particular when modes localized in the contact region are\npermitted to extend into the electrodes. As an example, we find that certain\nmodes can give rise to decreases in conductance when in the tunneling regime,\nopposite to the above mentioned result. Whereas details in the inelastic\nspectrum depend on the size of the vibrational region, we show that the overall\nchange in conductance is quantitatively well approximated by the simplest\ncalculation where only the apex atoms are allowed to vibrate. Our study is\ncompleted by the application of a simplified model where the relevant\nparameters are obtained from the above DFT-based calculations.",
        "positive": "The quantized Hall effect in the presence of resistance fluctuations: We present an experimental study of mesoscopic, two-dimensional electronic\nsystems at high magnetic fields. Our samples, prepared from a low-mobility\nInGaAs/InAlAs wafer, exhibit reproducible, sample specific, resistance\nfluctuations. Focusing on the lowest Landau level we find that, while the\ndiagonal resistivity displays strong fluctuations, the Hall resistivity is free\nof fluctuations and remains quantized at its $\\nu=1$ value, $h/e^{2}$. This is\ntrue also in the insulating phase that terminates the quantum Hall series.\nThese results extend the validity of the semicircle law of conductivity in the\nquantum Hall effect to the mesoscopic regime."
    },
    {
        "anchor": "Resonant subwavelength control of the phase of spin waves reflected from\n  a ferromagnetic film edge: Using frequency-domain finite element calculations cross-checked with\nmicromagnetic simulations, we demonstrate that the phase of spin waves\nreflected from an interface between a permalloy film and a bilayer can be\ncontrolled by changing dimensions of the bilayer. Treating the bilayer formed\nby the permalloy film and a ferromagnetic stripe as a segment of a multi-mode\nwaveguide, we show that spin-wave Fabry-Perot resonances of one of its modes\nare responsible for the high sensitivity of the phase of reflected waves to\nstripe width and the stripe-film separation. Thus, the system is a unique\nrealization of a fully magnonic Gires-Tournois interferometer based on a\ntwo-modes resonator, which can be treated as a magnonic counterpart of a\nmetasurface, since it enables manipulation of the phase of spin waves at\nsubwavelength distances. Knowledge gained from these calculations might be used\nto design magnonic devices such as flat lenses or magnetic particle detectors.",
        "positive": "General theory of emergent elasticity for second-order topological phase\n  transitions: The raise of the symmetry breaking mechanism by Landau[1] is a landmark in\nthe studies of phase transitions. The Kosterlitz-Thouless phase transition[2-3]\nand the fractional quantum Hall effect[4], however, are believed to be induced\nby another mechanism: topology change. Despite rapid development of the theory\nof topological orders[5-7], a unified theoretical framework describing this new\nparadigm of phase transition and its relation to the Landau paradigm, is not\nseen. Here, we establish such a framework based on variational principle, and\nshow that the critical condition for any second-order topological phase\ntransitions is loss of positive-definiteness of a topologically protected\nsecond-order variation of the free energy. A topologically protected variation\nof a field solution is performed with respect to its emergent displacements,\nwhich is introduced by constructing an emergent elasticity problem for the\nsolution. The Landau paradigm of phase transitions studies global property\nchanges induced instability, while topological phase transitions study local\nproperty changes induced topological instability. The general effectiveness of\nthis criterion is shown through analyzing the topological stability of several\nprototype solutions in both real space (two-kink solutions of the sine-Gordon\nmodel; an isolated skyrmion in chiral magnets) and reciprocal space (phonon\nspectrum of a monoatomic chain and a diatomic chain; band structure of a\nmonoatomic chain within the Kronig-Penny model). Every field is emergent\nelastic with spatially modulated stiffness, and changes of topological property\noccur at its softened points. We anticipate our work to be a starting point for\na general study of topological phase transitions in all field theories."
    },
    {
        "anchor": "The two classes of low energy spectra in finite carbon nanotubes: Electrons in carbon nanotubes (CNTs) possess spin and orbital degrees of\nfreedom. The latter is inherited from the bipartite graphene lattice with two\ninequivalent Dirac points. The electronic spectra obtained in several transport\nexperiments on CNT quantum dots in parallel magnetic field often show an\nanticrossing of spectral lines assigned to the opposite Dirac valleys. So far\nthis valley mixing has been attributed to the disorder, with impurity induced\nscattering. We show that this effect can arise also in ultraclean CNTs of the\narmchair class and it can be caused solely by the presence of the boundaries.\nIn contrast, in CNTs of the zigzag class it does not occur. These two\nfundamentally different classes of spectra arise because of different\nsymmetries of the low energy eigenstates of the two types of CNTs. The\nmagnitude of the level splitting depends in a nonmonotonous way on the distance\nof the involved energy levels from the charge neutrality point.",
        "positive": "Detecting the local transport properties and the dimensionality of\n  transport of epitaxial graphene by a multi-point probe approach: The electronic transport properties of epitaxial monolayer graphene (MLG) and\nhydrogen-intercalated quasi free-standing bilayer graphene (QFBLG) on SiC(0001)\nare investigated by micro multi-point probes. Using a probe with 12 contacts,\nwe perform four-point probe measurements with the possibility to effectively\nvary the contact spacing over more than one order of magnitude, allowing us to\nestablish that the transport is purely two-dimensional. Combined with the\ncarrier density obtained by angle-resolved photoemission spectroscopy, we find\nthe room temperature mobility of MLG to be (870+-120)cm2/Vs. The transport in\nQFBLG is also found to be two-dimensional with a mobility of (1600+-160)\ncm2/Vs."
    },
    {
        "anchor": "Vortex precession frequency and its amplitude-dependent shift in\n  cylindrical nanomagnets: Frequency of free magnetic vortex precession in circular soft ferromagnetic\nnano-cylinders (magnetic dots) of various sizes is an important parameter, used\nin design of spintronic devices (such as spin-torque microwave\nnano-oscillators) and characterization of magnetic nanostructures. Here, using\na recently developed collective-variable approach to non-linear dynamics of\nmagnetic textures in planar nano-magnets, this frequency and its\namplitude-dependent shift are computed analytically and plotted for the full\nrange of cylinder geometries. The frequency shift is positive in large planar\ndots, but becomes negative in smaller and more elongated ones. At certain dot\ndimensions a zero frequency shift is realized, which can be important for\nenhancing frequency stability of magnetic nano-oscillators.",
        "positive": "Coriolis force, geometric phase, and spin-electric coupling in\n  semiconductors: We consider the response of an effective spin of a charge carrier to an\nadiabatic rotation of its crystal momentum induced by electric field. This\nrotation gives rise to Coriolis pseudo-force that is responsible for torque\nacting on the orbital momentum of a particle. Mediated by a spin-orbit coupling\nin the valence band this perturbation leads to a spin-electric coupling that\nmay affect the coherent transport properties of a charge carrier and cause a\nspin precession in zero magnetic fields. In the static uniform electric field\nthe derived effective spin-Hamiltonians of the carriers in the conduction and\nlight hole bands are homologous to the Rashba Hamiltonian. These effects may be\nalso interpreted as a manifestation of, in general, a non-Abelian gauge\npotential and can be described in purely geometric terms as a consequence of\nthe corresponding holonomy. We demonstrate that in the conduction band the\nstrength of the associated covariant gauge field is proportional to the\neffective electron g-tensor and is controllable by gate fields or a strain\napplied to the crystal."
    },
    {
        "anchor": "Dynamical Magnetic and Nuclear Polarization in Complex Spin Systems:\n  Semi-magnetic II-VI Quantum Dots: Dynamical magnetic and nuclear polarization in complex spin systems is\ndiscussed on the example of transfer of spin from exciton to the central spin\nof magnetic impurity in a quantum dot in the presence of a finite number of\nnuclear spins. The exciton is described in terms of the electron and heavy hole\nspins interacting via exchange interaction with magnetic impurity, via\nhypeprfine interaction with a finite number of nuclear spins and via dipole\ninteraction with photons. The time-evolution of the exciton, magnetic impurity\nand nuclear spins is calculated exactly between quantum jumps corresponding to\nexciton radiative recombination. The collapse of the wavefunction and the\nrefilling of the quantum dot with new spin polarized exciton is shown to lead\nto build up of magnetization of the magnetic impurity as well as nuclear spin\npolarization. The competition between electron spin transfer to magnetic\nimpurity and to nuclear spins simultaneous with the creation of dark excitons\nis elucidated. The technique presented here opens up the possibility of\nstudying optically induced Dynamical Magnetic and Nuclear Polarization in\nComplex Spin Systems.",
        "positive": "From the spin eigenmodes of isolated N\u00e9el skyrmions to the magnonic\n  bands of a skyrmionic crystal: a micromagnetic study as a function of the\n  strength of both the interfacial Dzyaloshinskii-Moriya and the exchange\n  constants: The presence of interfacial Dzyaloshinskii-Moriya interaction (DMI) may lead\nto the appearance of N\\'eel skyrmions in ferromagnetic films. These\ntopologically protected structures, whose diameter is as small as a few\nnanometers, can be nowadays stabilized at room temperature and have been\nproposed for the realization of artificial magnonic crystals and new spintronic\ndevices, such as racetrack memories. In this perspective, it is of utmost\nimportance to analyze their dynamical properties in the GHz range, i.e. in the\noperation range of current communication devices. Here we exploited the\nsoftware MuMax3 to calculate the dynamics of N\\'eel skyrmions in the range\nbetween 1 and 30 GHz, considering first the eigenmodes of an isolated skyrmion,\nthen the case of two interacting skyrmions and finally a linear chain,\nrepresenting a one-dimensional magnonic crystal, whose magnonic band structure\nhas been calculated as a function of the strength of both the DMI- and the\nexchange-constants, namely D and A. The magnonic bands can be interpreted as\nderived from the eigenmodes of isolated skyrmions, even if hybridization and\nanti-crossing phenomena occur for specific ranges of values of D and A.\nTherefore, varying the latter parameters, for instance by a proper choice of\nthe materials and thicknesses, may enable one to fine-tune the permitted and\nforbidden frequency interval of the corresponding magnonic crystal."
    },
    {
        "anchor": "Temperature evolution of the quantum Hall effect in the FISDW state:\n  Theory vs Experiment: We discuss the temperature dependence of the Hall conductivity $\\sigma_{xy}$\nin the magnetic-field-induced spin-density-wave (FISDW) state of the\nquasi-one-dimensional Bechgaard salts (TMTSF)_2X. Electronic thermal\nexcitations across the FISDW energy gap progressively destroy the quantum Hall\neffect, so $\\sigma_{xy}(T)$ interpolates between the quantized value at zero\ntemperature and zero value at the transition temperature T_c, where FISDW\ndisappears. This temperature dependence is similar to that of the superfluid\ndensity in the BCS theory of superconductivity. More precisely, it is the same\nas the temperature dependence of the Fr\\\"ohlich condensate density of a regular\nCDW/SDW. This suggests a two-fluid picture of the quantum Hall effect, where\nthe Hall conductivity of the condensate is quantized, but the condensate\nfraction of the total electron density decreases with increasing temperature.\nThe theory appears to agree with the experimental results obtained by measuring\nall three components of the resistivity tensor simultaneously on a\n(TMTSF)_2PF_6 sample and then reconstructing the conductivity tensor.",
        "positive": "Electroluminescence and thermal radiation from metallic carbon nanotubes\n  with defects: Bias-induced light emission and thermal radiation from conducting channels of\ncarbon nanotubes (CNTs) with defects are studied theoretically within the\nframework of nonequilibrium Green's function method based on a tight-binding\nmodel. Localized states induced by the single vacancy defect and single\nStone-Wales defect in the low energy range enhance electroluminescence\nsignificantly while they reduce thermal radiation under zero bias. The\ninfluence of the diameters of the CNTs with defects on the radiation is\ndiscussed. Different from the 2D or bulk materials, the radiation intensities\nfrom quasi-one-dimensional metallic CNTs in thermal equilibrium are much\nsmaller than that of the black-body radiation. We attribute this to the\nconfinement of thermal excitation in the transverse direction of the CNT. Our\nstudy is important for optoelectronic applications of CNTs with defects."
    },
    {
        "anchor": "Fractional quantum Hall effect in CdTe: The fractional quantum Hall (FQH) effect is reported in a high mobility CdTe\nquantum well at mK temperatures. Fully-developed FQH states are observed at\nfilling factor 4/3 and 5/3 and are found to be both spin-polarized ground state\nfor which the lowest energy excitation is not a spin-flip. This can be\naccounted for by the relatively high intrinsic Zeeman energy in this single\nvalley 2D electron gas. FQH minima are also observed in the first excited (N=1)\nLandau level at filling factor 7/3 and 8/3 for intermediate temperatures.",
        "positive": "From single dots to interacting arrays: We explore the structural changes in charge the density and the electron\nconfiguration of quantum dots caused by the presence of other dots in an array,\nand the interaction of neighboring dots. We discuss what recent measurements\nand calculation of the far-infrared absorption reveal about almost isolated\nquantum dots and investigate some aspects of the complex transition from\nisolated dots to dots with strongly overlapping electron density. We also\naddress the the effects on the magnetization of such dot array."
    },
    {
        "anchor": "Low-Temperature Resistivity Anomalies in Periodic Curved Surfaces: Effects of periodic curvature on the the electrical resistivity of corrugated\nsemiconductor films are theoretically considered. The presence of a\ncurvature-induced potential affects the motion of electrons confined to the\nthin curved film, resulting in a significant resistivity enhancement at\nspecific values of two geometric parameters: the amplitude and period of the\nsurface corrugation. The maximal values of the two parameters in order to\nobserve the corrugation-induced resistivity enhancement in actual experiments\nare quantified by employing existing material constants.",
        "positive": "Persistent current in a mesoscopic ring with diffuse surface scattering: The persistent current in a clean mesoscopic ring with ballistic electron\nmotion is calculated. The particle dynamics inside a ring is assumed to be\nchaotic due to scattering at the surface irregularities of atomic size. This\nallows one to use the so-called ``ballistic'' supersymmetric \\sigma model for\ncalculation of the two-level correlation function in the presence of a nonzero\nmagnetic flux."
    },
    {
        "anchor": "Spin-Orbit Protection of Induced Superconductivity in Majorana Nanowires: Spin-orbit interaction (SOI) plays a key role in creating Majorana zero modes\nin semiconductor nanowires proximity coupled to a superconductor. We track the\nevolution of the induced superconducting gap in InSb nanowires coupled to a\nNbTiN superconductor in a large range of magnetic field strengths and\norientations. Based on realistic simulations of our devices, we reveal SOI with\na strength of 0.15-0.35 eV$\\require{mediawiki-texvc}\\AA$. Our approach\nidentifies the direction of the spin-orbit field, which is strongly affected by\nthe superconductor geometry and electrostatic gates.",
        "positive": "Changing the state of a memristive system with white noise: Can we change the average state of a resistor by simply applying white noise?\nWe show that the answer to this question is positive if the resistor has memory\nof its past dynamics (a memristive system). We also prove that, if the memory\narises only from the charge flowing through the resistor -- an ideal memristor\n-- then the current flowing through such memristor can not charge a capacitor\nconnected in series, and therefore cannot produce useful work. Moreover, the\nmemristive system may skew the charge probability density on the capacitor, an\neffect which can be measured experimentally."
    },
    {
        "anchor": "Effects of broadening and electron overheating in tunnel structures\n  based on metallic clusters: We study the influence of energy levels broadening and electron subsystem\noverheating in island electrode (cluster) on current-voltage characteristics of\nthree-electrode structure. A calculation scheme for broadening effect in\none-dimensional case is suggested. Estimation of broadening is performed for\nelectron levels in disc-like and spherical gold clusters. Within the\ntwo-temperature model of metallic cluster and by using a size dependence of the\nDebye frequency the effective electron temperature as a function of bias\nvoltage is found approximately. We suggest that the effects of broadening and\nelectron overheating are responsible for the strong smoothing of\ncurrent-voltage curves, which is observed experimentally at low temperatures in\nstructures based on clusters consisting of accountable number of atoms.",
        "positive": "Giant Spin Relaxation Anisotropy in Zinc-Blende Heterostructures: Spin relaxation in-plane anisotropy is predicted for heterostructures based\non zinc-blende semiconductors. It is shown that it manifests itself especially\nbrightly if the two spin relaxation mechanisms (D'yakonov-Perel' and Rashba)\nare comparable in efficiency. It is demonstrated that for the quantum well\ngrown along the [0 0 1] direction, the main axes of spin relaxation rate tensor\nare [1 1 0] and [1 -1 0]."
    },
    {
        "anchor": "Overcoming Boltzmann's Tyranny in a Transistor via the Topological\n  Quantum Field Effect: The sub-threshold swing is the fundamental critical parameter determining the\noperation of a transistor in low-power applications such as switches. It\ndetermines the fraction of dissipation due to the gate capacitance used for\nturning the device on and off, and in a conventional transistor it is limited\nby Boltzmann's tyranny to kTln(10)/q, or 60 mV per decade. Here, we demonstrate\nthat the sub-threshold swing of a topological transistor, in which conduction\nis enabled by a topological phase transition via electric field switching, can\nbe sizably reduced in a non-interacting system by modulating the Rashba\nspin-orbit interaction via a top-gate electric field. We refer to this as the\nTopological Quantum Field Effect and to the transistor as a Topological Quantum\nField Effect transistor (TQFET). By developing a general theoretical framework\nfor quantum spin Hall materials with honeycomb lattices we explicitly show that\nthe Rashba interaction can reduce the sub-threshold swing by more than 25%\ncompared to Boltzmann's limit in currently available materials, but without any\nfundamental lower bound, a discovery that can guide future materials design and\nsteer the engineering of topological quantum devices.",
        "positive": "Fermi-Luttinger liquid: Spectral function of interacting one-dimensional\n  fermions: We evaluate the spectral function of interacting fermions in one dimension.\nContrary to the Tomonaga-Luttinger model, our treatment accounts for the\nnonlinearity of the free fermion spectrum. In a striking departure from the\nLuttinger liquid theory, the spectrum nonlinearity restores the main feature of\nthe Fermi liquid: a Lorentzian peak in the spectral function on the particle\nmass-shell. At the same time, the spectral function displays a power-law\nsingularity on the hole mass-shell, similar to that in the Luttinger liquid."
    },
    {
        "anchor": "Persistent currents and magnetic flux trapping in fragments of carbon\n  deposits containing multiwalled nanotubes: It is found that the magnetization curves of samples of fragments of cathode\ncarbon deposits with a high content of multiwalled nanotubes exhibit a\npronounced irreversible character, attesting to the induction of persistent\ncurrents in the samples and to magnetic flux trapping, as happens in a multiply\nconnected superconducting structure. A decrease of the trapped flux in time\ncould not be observed at low (helium) temperatures with a measurement time of\nabout 20 h. For intermediate (~30K) and room temperatures the trapped magnetic\nflux decays slowly with characteristic relaxation times of the order of 150 and\n15 h, respectively.",
        "positive": "Variational approach to the stationary spin-Hall effect: The Kirchhoff-Helmholtz principle of least heat dissipation is applied in\norder to derive the stationary state of the spin-Hall effect. Spin-accumulation\ndue to spin-orbit interaction, spin-flip relaxation, and electrostatic\ninteraction due to charge accumulation are treated on an equal footing. A\nnonlinear differential equation is derived, that describes both surface and\nbulk currents and spin-dependent chemical potentials. It is shown that if the\nratio of the spin-flip relaxation length over the Debye-Fermi length is small,\nthe stationary state is defined by a linear spin-accumulation potential and\nzero pure spin-current."
    },
    {
        "anchor": "Temperature dependent reversal of voltage modulated light emission and\n  negative capacitance in AlGaInP based multi quantum well light emitting\n  devices: We report a reversal in negative capacitance and voltage modulated light\nemission from AlGaInP based multi-quantum well electroluminescent diodes under\ntemperature variation. Unlike monotonically increasing CW light emission with\ndecreasing temperature, modulated electroluminescence and negative capacitance\nfirst increase to a maximum and then decrease while cooling down from room\ntemperature. Interdependence of such electronic and optical properties is\nunderstood as a competition between defect participation in radiative\nrecombination and field assisted carrier escape from the quantum well region\nduring temperature variation. The temperature of maximum light emission must\ncoincide with the operating temperature of a device for better efficiency.",
        "positive": "Anticrossing-induced optical excitonic Aharonov-Bohm effect in strained\n  type-I semiconductor nanorings: The exciton states in strained (In,Ga)As nanorings embedded in a GaAs matrix\nare computed. The strain distribution is extracted from the continuum\nmechanical model, and the exact diagonalization approach is employed to compute\nthe exciton states. Weak oscillations of the ground exciton state energy with\nthe magnetic field normal to the ring are an expression of the excitonic\nAharonov-Bohm effect. Those oscillations arise from anticrossings between the\nground and the second exciton state and can be enhanced by increasing the ring\nwidth. Simultaneously, the oscillator strength for exciton recombination\nexhibits oscillations, which are superposed on a linear increase with magnetic\nfield. The obtained results are contrasted with previous theoretical results\nfor 1D rings, and differences are explained to arise from different confinement\npotentials for the electron and the hole, and the large diamagnetic shift\npresent in the analyzed type-I rings. Furthermore, our theory agrees\nqualitatively well with previous photoluminescence measurements on type-II\nInP/GaAs quantum dots."
    },
    {
        "anchor": "Electro-Mechanical Response of Top-Gated LaAlO3/SrTiO3 Heterostructures: LaAlO3/SrTiO3 heterostructures are known to exhibit a sharp, hysteretic\nmetal-insulator transition (MIT) with large enhanced capacitance near\ndepletion. To understand the physical origin of this behavior, the\nelectromechanical response of top-gated LaAlO3/SrTiO3 heterostructures is\nprobed using two simultaneous measurement techniques: piezoforce microscopy\n(PFM) and capacitance spectroscopy. PFM measurements reveal local variations in\nthe hysteretic response, which is directly correlated with capacitance\nmeasurements. The enhanced capacitance at the MIT is linked to\ncharging/discharging dynamics of nanoscale conducting islands, which are\nrevealed through PFM imaging and time-resolved capacitance and piezoresponse\nmeasurements.",
        "positive": "Accidental Degeneracy in k-space, Geometrical Phase, and the\n  Perturbation of $\u03c0$ by Spin-orbit Interactions: Since closed lines of {\\it accidental} electronic degeneracies were\ndemonstrated to be possible, even frequent, by Herring in 1937, no further\ndevelopments arose for eight decades. The earliest report of such a nodal loop\nin a real material -- aluminum -- is recounted and elaborated on. Nodal loop\nsemimetals have become a focus of recent activity, with emphasis on other\nissues. Band degeneracies are, after all, the origin of topological phases in\ncrystalline materials. Spin-orbit interaction lifts accidental band\ndegeneracies, with the resulting spectrum being provided here. The geometric\nphase $\\gamma(C)=\\pm\\pi$ for circuits $C$ surrounding a line of such degeneracy\ncannot survive completely unchanged. The change depends on how the spin is\nfixed during adiabatic evolution. For spin fixed along the internal spin-orbit\nfield, $\\gamma(C)$ decreases to zero as the circuit collapses around the line\nof lifted degeneracy. For spin fixed along a perpendicular axis, the conical\nintersection persists and $\\gamma(C)=\\pm\\pi$ is unchanged."
    },
    {
        "anchor": "Graphene-based amplification and tuning of near-field radiative heat\n  transfer between dissimilar polar materials: The radiative heat transfer between two dielectrics can be strongly enhanced\nin the near field in the presence of surface phonon-polariton resonances.\nNevertheless, the spectral mismatch between the surface modes supported by two\ndissimilar materials is responsible for a dramatic reduction of the radiative\nheat flux they exchange. In the present paper we study how the presence of a\ngraphene sheet, deposited on the material supporting the surface wave of lowest\nfrequency, allows to widely tune the radiative heat transfer, producing an\namplification factor going up to one order of magnitude. By analyzing the\nLandauer energy transmission coefficients we demonstrate that this\namplification results from the interplay between the delocalized plasmon\nsupported by graphene and the surface polaritons of the two dielectrics. We\nfinally show that the effect we highlight is robust with respect to the\nfrequency mismatch, paving the way to an active tuning and amplification of\nnear-field radiative heat transfer in different configurations.",
        "positive": "Berry phase of phonons and thermal Hall effect in nonmagnetic insulators: A mechanism for phonon Hall effect (PHE) in non-magnetic insulators under an\nexternal magnetic field is theoretically studied. PHE is known in\n(para)magnetic compounds, where the magnetic moments and spin-orbit interaction\nplay an essential role. In sharp contrast, we here show that a non-zero Berry\ncurvature of acoustic phonons is induced by an external magnetic field due to\nthe correction to the adiabatic Born-Oppenheimer approximation. This results in\nthe finite thermal Hall conductivity $\\kappa_H$ in nonmagnetic band insulators.\nOur estimate of $\\kappa_H$ for a simple model gives $\\kappa_H \\sim 1.0\\times\n10^{-5} $[W/Km] at $ B=10 $[T] and $ T=150 $[K]."
    },
    {
        "anchor": "Observation of Quantum Oscillations in the Photo-assisted Shot Noise of\n  a Tunnel Junction: We report measurements of the low frequency current fluctuations of a tunnel\njunction placed at very low temperature biased by a time-dependent voltage\n$V(t)=V(1+\\cos 2\\pi\\nu t)$. We observe that the excess noise generated by the\nac excitation exhibits quantum oscillations as a function of the dc bias, with\na period given by $h\\nu/e$ with $e$ the charge of a single electron. This is a\ndirect consequence of the quantum nature of electricity in a normal conductor.",
        "positive": "Graphene Based Plasmonic Tunable Low Pass Filters in the THz Band: We propose the concept, synthesis, analysis, and design of graphene-based\nplasmonic tunable low-pass filters operating in the THz band. The proposed\nstructure is composed of a graphene strip transferred onto a dielectric and a\nset of polysilicon DC gating pads located beneath it. This structure implements\na stepped impedance low-pass filter for the propagating surface plasmons by\nadequately controlling the guiding properties of each strip section through\ngraphene's field effect. A synthesis procedure is presented to design filters\nwith desired specifications in terms of cut-off frequency, in-band performance,\nand rejection characteristics. The electromagnetic modeling of the structure is\nefficiently performed by combining an electrostatic scaling law to compute the\nguiding features of each strip section with a transmission line and\ntransfer-matrix framework, approach further validated via full wave\nsimulations. The performance of the proposed filters is evaluated in practical\nscenarios, taking into account the presence of the gating bias and the\ninfluence of graphene's losses. These results, together with the high\nminiaturization associated with plasmonic propagation, are very promising for\nthe future use and integration of the proposed filters with other graphene and\nsilicon-based elements in innovative THz communication systems."
    },
    {
        "anchor": "Chiral Dirac Superconductors: Second-order and Boundary-obstructed\n  Topology: We analyze the topological properties of a chiral ${p}+i{p}$ superconductor\nfor a two-dimensional metal/semimetal with four Dirac points. Such a system has\nbeen proposed to realize second-order topological superconductivity and host\ncorner Majorana modes. We show that with an additional $\\mathsf{C}_4$\nrotational symmetry, the system is in an intrinsic higher-order topological\nsuperconductor phase, and with a lower and more natural $\\mathsf{C}_2$\nsymmetry, is in a boundary-obstructed topological superconductor phase. The\nboundary topological obstruction is protected by a bulk Wannier gap. However,\nwe show that the well-known nested-Wilson loop is in general unquantized\ndespite the particle-hole symmetry, and thus fails as a topological invariant.\nInstead, we show that the higher-order topology and boundary-obstructed\ntopology can be characterized using an alternative defect classification\napproach, in which the corners of a finite sample is treated as a defect of a\nspace-filling Hamiltonian. We establish \"Dirac+$({p}+i{p})$\" as a sufficient\ncondition for second-order topological superconductivity.",
        "positive": "Modeling and tackling resistivity scaling in metal nanowires: A self-consistent analytical solution of the multi-subband Boltzmann\ntransport equation with collision term describing grain boundary and surface\nroughness scattering is presented to study the resistivity scaling in metal\nnanowires. The different scattering mechanisms and the influence of their\nstatistical parameters are analyzed. Instead of a simple power law relating the\nheight or width of a nanowire to its resistivity, the picture appears to be\nmore complicated due to quantum-mechanical scattering and quantization effects,\nespecially for surface roughness scattering."
    },
    {
        "anchor": "Physics of Proximity Josephson Sensor: We study the proximity Josephson sensor (PJS) in both bolometric and\ncalorimetric operation and optimize it for different temperature ranges between\n25 mK and a few Kelvin. We investigate how the radiation power is absorbed in\nthe sensor and find that the irradiated sensor is typically in a weak\nnonequilibrium state. We show in detail how the proximity of the\nsuperconductors affects the device response: for example via changes in\nelectron-phonon coupling and out-of-equilibrium noise. In addition, we estimate\nthe applicability of graphene as the absorber material.",
        "positive": "Cross-plane heat conduction in thin films with ab-initio phonon\n  dispersions and scattering rates: We present a first-principles study of the cross-plane thermal conductivity\n$\\kappa_{\\perp}$ in a wide variety of semiconductor thin films. We introduce a\nsimple suppression model that matches variance-reduced Monte Carlo simulations\nwith ab-initio phonon dispersions and scattering rates within $\\leq 5\\%$ even\nfor anisotropic compounds. This, in turn, enables accurate $\\kappa_{\\perp}$\nreconstruction from tabulated cumulative conductivity curves\n$\\kappa_{\\Sigma}(\\Lambda_{\\perp})$. We furthermore reveal, and explain, a\ndistinct quasiballistic regime characterised by a fractional thickness\ndependence $\\kappa_{\\perp} \\sim L^{2-\\alpha}$ in alloys (where $\\alpha$ is the\nL\\'evy exponent) and logarithmic dependence $\\kappa_{\\perp} \\sim \\ln(L)$ in\nsingle crystals. These observations culminate in the formulation of two compact\nparametric forms for $\\kappa_{\\perp}(L)$ that can fit the first-principles\ncurves across the entire ballistic-diffusive range within a few percent for all\ninvestigated compounds."
    },
    {
        "anchor": "Current-phase relations of few-mode InAs nanowire Josephson junctions: Gate-tunable semiconductor nanowires with superconducting leads have great\npotential for quantum computation and as model systems for mesoscopic Josephson\njunctions. The supercurrent, $I$, versus the phase, $\\phi$, across the junction\nis called the current-phase relation (CPR). It can reveal not only the\namplitude of the critical current, but also the number of modes and their\ntransmission. We measured the CPR of many individual InAs nanowire Josephson\njunctions, one junction at a time. Both the amplitude and shape of the CPR\nvaried between junctions, with small critical currents and skewed CPRs\nindicating few-mode junctions with high transmissions. In a gate-tunable\njunction, we found that the CPR varied with gate voltage: Near the onset of\nsupercurrent, we observed behavior consistent with resonant tunneling through a\nsingle, highly transmitting mode. The gate dependence is consistent with\nmodeled subband structure that includes an effective tunneling barrier due to\nan abrupt change in the Fermi level at the boundary of the gate-tuned region.\nThese measurements of skewed, tunable, few-mode CPRs are promising both for\napplications that require anharmonic junctions and for Majorana readout\nproposals.",
        "positive": "Heat transport in Weyl semimetals in the hydrodynamic regime: We study heat transport in a Weyl semimetal with broken time-reversal\nsymmetry in the hydrodynamic regime. At the neutrality point, the longitudinal\nheat conductivity is governed by the momentum relaxation (elastic) time, while\nlongitudinal electric conductivity is controlled by the inelastic scattering\ntime. In the hydrodynamic regime this leads to a large longitudinal Lorenz\nratio. As the chemical potential is tuned away from the neutrality point, the\nlongitudinal Lorenz ratio decreases because of suppression of the heat\nconductivity by the Seebeck effect. The Seebeck effect (thermopower) and the\nopen circuit heat conductivity are intertwined with the electric conductivity.\nThe magnitude of Seebeck tensor is parametrically enhanced, compared to the\nnon-interacting model, in a wide parameter range. While the longitudinal\ncomponent of Seebeck response decreases with increasing electric anomalous Hall\nconductivity $\\sigma_{xy}$, the transverse component depends on $\\sigma_{xy}$\nin a non-monotonous way. Via its effect on the Seebeck response, large\n$\\sigma_{xy}$ enhances the longitudinal Lorenz ratio at a finite chemical\npotential. At the neutrality point, the transverse heat conductivity is\ndetermined by the Wiedemann-Franz law. Increasing the distance from the\nneutrality point, the transverse heat conductivity is enhanced by the\ntransverse Seebeck effect and follows its non-monotonous dependence on\n$\\sigma_{xy}$."
    },
    {
        "anchor": "Pseudodiffusive conductance, quantum-limited shot noise, and\n  Landau-level hierarchy in biased graphene bilayer: We discuss, by means of mode-matching analysis for the Dirac equation, how\nsplittings of the Landau-level (LL) degeneracies associated with spin, valley,\nand layer degrees of freedom affect the ballistic conductance of graphene\nbilayer. The results show that for wide samples ($W\\gg{}L$) the\nLandauer-B\\\"{u}ttiker conductance reaches the maximum\n$G\\simeq{}se^2/(\\pi{h})\\times{}W/L$ at the resonance via each LL, with the\nprefactor varying from $s=8$ if all three degeneracies are preserved, to $s=1$\nif all the degeneracies are split. In the absence of bias between the layers,\nthe degeneracies associated with spin and layer degrees of freedom may be split\nby manipulating the doping and magnetic field; the conductance at the zeroth LL\nis twice as large, while the conductance at any other LL equals to the\ncorresponding conductance of graphene monolayer. The presence of bias potential\nallows one also to split the valley degeneracy. Our results show that the\ncharge transfer at each LL has pseudodiffusive character, with the second and\nthird cumulant quantified by ${\\cal F}=1/3$ and ${\\cal R}=1/15$ (respectively).\nIn case the electrochemical potential is allowed to slowly fluctuate in a\nfinite vicinity of LL, the resulting charge-transfer characteristics are still\nquantum-limited, with ${\\cal F}\\simeq{}0.7$ and ${\\cal R}\\simeq{}0.5$ in the\nlimit of large fluctuations. The above values of ${\\cal F}$ and ${\\cal R}$ are\nalso predicted to be approached in the limit of high source-drain voltage\ndifference applied. The possible effects of indirect interlayer hopping\nintegrals are also briefly discussed.",
        "positive": "Direct measurement of acoustic spectral density and fractional\n  topological charge: Local density-of-states (LDOS) is a fundamental spectral property that plays\na central role in various physical phenomena such as wave-matter interactions.\nHere, we report on the direct measurement of the LDOS of acoustic systems and\nderive from which the fractional topological number in an acoustic\nSu-Schrieffer-Heeger system. The acoustic LDOS is quantified here with a\nstate-of-the-art technique through the measurement of the volume flow rate and\nthe acoustic pressure with a local excitation-probe configuration. Based on\nthis method, we study the acoustic Purcell effect and establish experimentally\nthe important relation between the near-field LDOS and the far-field acoustic\nemission power. Moreover, we detect the LDOS in the one-dimensional acoustic\nSu-Schrieffer-Heeger model and observe the fractional topological number of the\nsystem. Our work unveils the important role of the LDOS in acoustic phenomena\nand paves the way toward characterizing and tailoring the LDOS in topological\nsystems."
    },
    {
        "anchor": "Diffusion thermopower of a $p-$type Si/Si$_{1-x}$Ge$_x$ heterostructure\n  at zero field: This paper has been withdrawn by the author because it is superseded by a new\npreprint: Tran Doan Huan & Nguyen Phuc Hai: arXiv:1010.5162.",
        "positive": "Nonreciprocal Spin Waves Driven by Left-Hand Microwaves: It is a conventional wisdom that a left-hand microwave cannot efficiently\nexcite the spin wave (SW) in ferromagnets, due to the constraint of angular\nmomentum conservation. In this work, we show that the left-hand microwave can\ndrive nonreciprocal SWs in the presence of a strong ellipticity-mismatch\nbetween the microwave and precessing magnetization. A critical frequency is\npredicted, at which the left-hand microwave cannot excite SWs. Away from it the\nSW amplitude sensitively depends on the ellipticity of left-hand microwaves, in\nsharp contrast to the case driven by right-hand ones. By tuning the microwave\nfrequency, we observe a switchable SW non-reciprocity in a ferromagnetic single\nlayer. A mode-dependent mutual demagnetizing factor is proposed to explain this\nfinding. Our work advances the understanding of the photon-magnon conversion,\nand paves the way to designing diode-like functionalities in nano-scaled\nmagnonics."
    },
    {
        "anchor": "Spiro-Conjugated Molecular Junctions: between Jahn-Teller Distortion and\n  Destructive Quantum Interference: The quest for molecular structures exhibiting strong quantum interference\neffects in the transport setting has long been on the forefront of chemical\nresearch. Here, we establish theoretically that the unusual geometry of\nspiro-conjugated systems gives rise to complete destructive interference in the\nresonant-transport regime. This results in a current blockade of the type not\npresent in meta-connected benzene or similar molecular structures. We further\nshow that these systems can undergo a transport-driven Jahn-Teller distortion\nwhich can lift the aforementioned destructive-interference effects. The overall\ntransport characteristics is determined by the interplay between the two\nphenomena. Spiro-conjugated systems may therefore serve as a novel platform for\ninvestigations of quantum interference and vibronic effects in the charge\ntransport setting. The potential to control quantum interference in these\nsystems can also turn them into attractive components in designing functional\nmolecular circuits.",
        "positive": "Intrinsic coherence dynamics and phase localization in Aharonov-Bohm\n  Interferometers: The nonequilibrium real-time dynamics of electron coherence is explored in\nthe quantum transport through the double-dot Aharonov-Bohm interferometers. We\nsolve the exact master equation to find the exact quantum state of the device,\nfrom which the changes of the electron coherence through the magnetic flux in\nthe nonequilibrium transport processes is obtained explicitly. We find that the\nrelative phase between the two charge states of the double dot localizes to\n$\\frac{\\pi}{2}$ or $-\\frac{\\pi}{2}$ for all different magnetic flux. This\nnontrivial phase localization process can be manifested in the measurable\noccupation numbers."
    },
    {
        "anchor": "Elastic backscattering of quantum spin Hall edge modes from Coulomb\n  interactions with non-magnetic impurities: We demonstrate that electrostatic interactions between helical electrons at\nthe edge of a quantum spin Hall insulator and a dynamical impurity can induce\nquasi-elastic backscattering. Modelling the impurity as a two-level system, we\nshow that transitions between counterpropagating Kramers-degenerate electronic\nstates can occur without breaking time-reversal symmetry, provided that the\nimpurity also undergoes a transition. The associated electrical resistance has\na weak temperature dependence down to a non-universal temperature scale. Our\nresults extend the range of known backscattering mechanisms in helical edge\nmodes to include scenarios where electron tunnelling out of the system is\nabsent.",
        "positive": "Fast control of semiconductor qubits beyond the rotating-wave\n  approximation: We present a theoretical study of single-qubit operations by oscillatory\nfields on various semiconductor platforms. We explicitly show how to perform\nfaster gate operations by going beyond the universally-used rotating wave\napproximation (RWA) regime, while using only two sinusoidal pulses. No\ncomplicated pulse shaping or optimal control sequences are required. We first\nshow for specific published experiments how much error is currently incurred by\nimplementing pulses designed using standard RWA. We then show that an even\nmodest increase in gate speed would cause problems in using RWA for gate design\nin the singlet-triplet (ST) and resonant-exchange (RX) qubits. We discuss the\nextent to which analytically keeping higher orders in the perturbation theory\nwould address the problem. More strikingly, we give a new prescription for\ngating with strong coupling far beyond the RWA regime. We perform numerical\ncalculations for the phases and the durations of two consecutive pulses to\nrealize the key Hadamard and $\\frac{\\pi}{8}$ gates with coupling strengths up\nto several times the qubit splitting. Working in this manifestly non-RWA\nregime, the gate operation speeds up by two to three orders of magnitude."
    },
    {
        "anchor": "Enhanced magnon spin current using the bosonic Klein paradox: Efficient manipulation of magnons for information processing is a central\ntopic in spintronics and magnonics. An outstanding challenge for long-distance\nspin transport with minimal dissipation is to overcome the relaxation of\nmagnons and to amplify the spin current they carry. Here, we propose to amplify\nmagnon currents based on the realization of the bosonic Klein paradox in\nmagnetic nanostructures. This paradox involves the magnon's antiparticle, the\nantimagnon, of which the existence is usually precluded by magnetic\ninstabilities as it is an excitation at negative energy. We show that, by\nappropriately tuning the effective dissipation through spin-orbit torques, both\nmagnons and antimagnons are dynamically stabilized. As a result, we find that\nthe reflection coefficient of incident magnons at an interface between two\ncoupled magnets can become larger than one, thereby amplifying the reflected\nmagnon current. Our findings can lead to magnon amplifier devices for\nspintronic applications. Furthermore, our findings yield a solid-state platform\nto study the relativistic behavior of bosonic particles, which is an\noutstanding challenge with fundamental particles.",
        "positive": "Linear magnetoresistance in HgTe quantum wells: We report magnetotransport measurements in a HgTe quantum well with an\ninverted band structure, which is expected to be a two-dimensional (2D)\ntopological insulator. A small magnetic field perpendicular the 2D layer breaks\nthe time reversal symmetry and thereby, suppresses the edge state transport. A\nlinear magnetoresistance is observed in low magnetic fields, when the chemical\npotential moves through the the bulk gap. That magnetoresistance is well\ndescribed by numerical calculations of the edge states magnetotransport in the\npresence of nonmagnetic disorder. With magnetic field increasing the\nresistance, measured both in the local and nonlocal configurations first\nsharply decreases and then increases again in disagreement with the existing\ntheories."
    },
    {
        "anchor": "Electron Interactions and Gap Opening in Graphene Superlattices: We develop a theory of interaction effects in graphene superlattices, where\ntunable superlattice periodicity can be used as a knob to control the gap at\nthe Dirac point. Applied to graphene on hexa-boron-nitride (G/h-BN), our theory\npredicts substantial many-body enhancement of this gap. Tunable by the moire\nsuperlattice periodicity, a few orders of magnitude enhancement is reachable\nunder optimal conditions. The Dirac point gap enhancement can be much larger\nthan that of the minigaps opened by Bragg scattering at principal superlattice\nharmonics. This naturally explains the conundrum of large Dirac point gaps\nrecently observed in G/h-BN heterostructures and their tunability by the G/h-BN\ntwist angle.",
        "positive": "Quantum magnetism and topological superconductivity in Yu-Shiba-Rusinov\n  chains: Chains of magnetic adatoms on superconductors have been discussed as\npromising systems for realizing Majorana end states. Here, we show that dilute\nYu-Shiba-Rusinov (YSR) chains are also a versatile platform for quantum\nmagnetism and correlated electron dynamics, with widely adjustable spin values\nand couplings. Focusing on subgap excitations, we derive an extended $t-J$\nmodel for dilute quantum YSR chains and use it to study the phase diagram as\nwell as tunneling spectra. We explore the implications of quantum magnetism for\nthe formation of a topological superconducting phase, contrasting it to\nexisting models assuming classical spin textures."
    },
    {
        "anchor": "Study of partially polarized fractional quantum Hall states: We have studied the partially spin-polarized fractional quantum Hall states\nusing Chern Simon's theory and plasma picture proposed by Halperin. Using these\ntheoretical techniques we have tried to find the stable polarized states of\ndifferent filling fractions observed in experiments. We have calculated the\nground state energies of those states and also pair correlation function. We\nhave described the nature of the states by the behaviour of this quantity. In\nour study, we have seen that the partially polarized states, which do not fit\nwith Jain's composite fermion description are basically the mixed state of\nup-spin liquid phase and down-spin solid phase.",
        "positive": "Comment on ``Density of States of Disordered Two-Dimensional Crystals\n  with Half-Filled Band'': In a recent letter (PRL 84, 3930 (2000)) Nakhmedov et al. claimed that the\nVan Hove singularity at $\\epsilon=0$ in the density of states (DoS) of the\ntwo-dimensional crystal with half-filled tight-binding band survives the\naddition of substitutional impurities. This derivation suffers from several\ninconsistencies. We resolve them and show that the DoS at the band center is\nfinite, as one might naively expect."
    },
    {
        "anchor": "Theory of Zero-Bias Anomaly in Magnetic Tunnel Junctions: Inelastic\n  Tunneling via Impurities: Using the closed-time path integral approach, we nonperturbatively study\ninelastic tunneling of electrons via magnetic impurities in the barrier\naccompanied by phonon emission in a magnetic tunnel junction. The spectrum\ndensity of phonon emission is found to show a power-law infrared singularity\n$\\sim\\omega^{-(1-g)}$ with $g$ the dimensionless electron-phonon coupling. As a\nconsequence, the tunneling conductance $G(V)$ increases with bias voltage $|\nV|$ as $G(V)-G(0)\\sim| V|^{2g}$, exhibiting a discontinuity in slope at V=0 for\n$g\\le 0.5$. This theory can reproduce both cusp-like and non-cusp-like feature\nof the zero-bias anomaly of tunneling resistance and magnetoresistance widely\nobserved in experiments.",
        "positive": "Cavity Quantum Electrodynamics with Hyperbolic van der Waals Materials: The ground-state properties and excitation energies of a quantum emitter can\nbe modified in the ultrastrong coupling regime of cavity quantum\nelectrodynamics (QED) where the light-matter interaction strength becomes\ncomparable to the cavity resonance frequency. Recent studies have started to\nexplore the possibility of controlling an electronic material by embedding it\nin a cavity that confines electromagnetic fields in deep subwavelength scales.\nCurrently, there is a strong interest in realizing ultrastrong-coupling cavity\nQED in the terahertz (THz) part of the spectrum, since most of the elementary\nexcitations of quantum materials are in this frequency range. We propose and\ndiscuss a promising platform to achieve this goal based on a two-dimensional\nelectronic material encapsulated by a planar cavity consisting of ultrathin\npolar van der Waals crystals. As a concrete setup, we show that nanometer-thick\nhexagonal boron nitride layers should allow one to reach the ultrastrong\ncoupling regime for single-electron cyclotron resonance in a bilayer graphene.\nThe proposed cavity platform can be realized by a wide variety of thin\ndielectric materials with hyperbolic dispersions. Consequently, van der Waals\nheterostructures hold the promise of becoming a versatile playground for\nexploring the ultrastrong-coupling physics of cavity QED materials."
    },
    {
        "anchor": "Strong coupling in the far-infrared between graphene plasmons and the\n  surface optical phonons of silicon dioxide: We study plasmonic resonances in electrostatically gated graphene nanoribbons\non silicon dioxide substrates. Absorption spectra are measured in the mid-far\ninfrared and reveal multiple peaks, with width-dependent resonant frequencies.\nWe calculate the dielectric function within the random phase approximation and\nshow that the observed spectra can be explained by\nsurface-plasmon-phonon-polariton modes, which arise from coupling of the\ngraphene plasmon to three surface optical phonon modes in the silicon dioxide.",
        "positive": "Structural and Electronic Properties of Graphdiyne Carbon Nanotubes from\n  Large-Scale DFT Calculations: Using large-scale DFT calculations, we have investigated the structural and\nelectronic properties of both armchair and zigzag graphdiyne nanotubes as a\nfunction of size. To provide insight in these properties, we present new\ndetailed calculations of the structural relaxation energy, effective\nelectron/hole mass, and size-scaling of the bandgap as a function of size and\nchirality using accurate screened-exchange DFT calculations. These calculations\nprovide a systematic evaluation of the structural and electronic properties of\nthe largest graphdiyne nanotubes to date - up to 1,296 atoms and 23,328 basis\nfunctions. Our calculations find that zigzag graphdiyne nanotubes (GDNTs) are\nstructurally more stable compared to armchair GDNTs of the same size.\nFurthermore, these large-scale calculations allow us to present simple\nanalytical formulae to guide future experimental efforts for estimating the\nfundamental bandgaps of these unique nanotubes as a function of chirality and\ndiameter. While the bandgaps for both the armchair and zigzag GDNTs can be\ntuned as a function of size, the conductivity in each of these two different\nchiralities is markedly different. Zigzag GDNTs have wider valence and\nconduction bands and are expected to have a higher electron- and hole-mobility\nthan their armchair counterparts."
    },
    {
        "anchor": "Metal-insulator transitions in bilayer electron-hole systems in\n  transition metal dicalcogenides: We investigated metal-insulator transitions for double layer two-dimensional\nelectron hole systems in transition metal dicalcogenides (TMDC) stacked on\nopposite sides of thin layers of boron nitride (BN). The interparticle\ninteraction is calculated by including the screening due to the polarization\ncharges at different interfaces, including that at the encapsultion and the\nsubstrate of experimental structures. We compute and compare the energies of\nthe metallic electron-hole plasma and the newly proposed insulating exciton\nsolid with fixed-node diffusion Monte Carlo simulation including the high\nvalley degeneracy of the electron bands. We found that for some examples of\ncurrent experimental structures, the transition electron/hole density is in an\naccessible range of g x 10^12 /cm*2 with g between 4.1 and 14.5 for spacer\nthicknesses between 2.5 and 7.5 nm. Our result raise the possibility of\nexploiting this effect for logic device applications.",
        "positive": "Modulation theory of quantum tunneling into a Calogero-Sutherland fluid: Quantum hydrodynamics of interacting electrons with a parabolic single\nparticle spectrum is studied using the Calogero-Sutherland model. The effective\naction and modulation equations, describing evolution of periodic excitations\nin the fluid, are derived. Applications to the problem of a single electron\ntunneling into the FQHE edge state are discussed."
    },
    {
        "anchor": "Infrared to terahertz optical conductivity of $n$-type and $p$-type\n  monolayer MoS$_2$ in the presence of Rashba spin-orbit coupling: We investigate the effect of Rashba spin-orbit coupling (SOC) on the\noptoelectronic properties of n- and p-type monolayer MoS2. The optical\nconductivity is calculated within the Kubo formalism. We find that the\nspin-flip transitions enabled by the Rashba SOC result in a wide absorption\nwindow in the optical spectrum. Furthermore, we evaluate the effects of the\npolarization direction of the radiation, temperature, carrier density, and the\nstrength of the Rashba spin-orbit parameter on the optical conductivity. We\nfind that the position, width, and shape of the absorption peak or absorption\nwindow can be tuned by varying these parameters. This study shows that\nmonolayer MoS2 can be a promising tunable optical and optoelectronic material\nthat is active in the infrared to terahertz spectral range.",
        "positive": "Electron spin diffusion and transport in graphene: We investigate the spin diffusion and transport in a graphene monolayer on\nSiO$_2$ substrate by means of the microscopic kinetic spin Bloch equation\napproach. The substrate causes a strong Rashba spin-orbit coupling field $\\sim\n0.15$ meV, which might be accounted for by the impurities initially present in\nthe substrate or even the substrate-induced structure distortion. By surface\nchemical doping with Au atoms, this Rashba spin-orbit coupling is further\nstrengthened as the adatoms can distort the graphene lattice from $sp^2$ to\n$sp^3$ bonding structure. By fitting the Au doping dependence of spin\nrelaxation from Pi {\\sl et al.} [Phys. Rev. Lett. {\\bf 104}, 187201 (2010)],\nthe Rashba spin-orbit coupling coefficient is found to increase approximately\nlinearly from 0.15 to 0.23 meV with the increase of Au density. With this\nstrong spin-orbit coupling, the spin diffusion or transport length is\ncomparable with the experimental values. In the strong scattering limit\n(dominated by the electron-impurity scattering in our study), the spin\ndiffusion is uniquely determined by the Rashba spin-orbit coupling strength and\ninsensitive to the temperature, electron density as well as scattering. With\nthe presence of an electric field along the spin injection direction, the spin\ntransport length can be modulated by either the electric field or the electron\ndensity. (The remaining is omitted due to the limit of space)"
    },
    {
        "anchor": "Splitting of Landau levels of a 2D electron due to electron-phonon\n  interactions: We show that in a very strong magnetic field $B$ electron-phonon interaction\ngives rise to a splitting of Landau levels of a 2D electron into a series of\ninfinitely degenerate sublevels. We provide both qualitative and quantitative\ndescription of this phenomenon. The cases of interaction with acoustic and\npolar optical phonons are considered. The energy distance between nearest\nsublevels in both cases tends to zero as $B^{-1/2}$ at large $B$.",
        "positive": "Ultrafast terahertz responses in monolayer graphene: We theoretically investigate the ultrafast terahertz(THz) properties of\nmonolayer graphene. The analytical formulations of the photon carrier, electric\npolarization and optical current are obtained by solving the Bloch-equations in\npresent of the ultrafast THz Gaussian pulse. Graphene shows a large nonlinear\nand ultrafast optical response at THz frequencies due to the gapless and\nrelativistic Dirac particles with nearly linear energy dispersion. It is found\nthat the photon carrier density, electric polarization and optical current\ndensity increase with increasing the frequency of the THz pulse. These\ntheoretical results are in agreement with recent experimental findings. This\nstudy confirms further that graphene exhibits important features and is\nrelevant to the applications in the ultrafast THz fields."
    },
    {
        "anchor": "Temporal and spectral fingerprints of ultrafast all-coherent spin\n  switching: Future information technology demands ultimately fast, low-loss quantum\ncontrol. Intense light fields have facilitated important milestones, such as\ninducing novel states of matter, accelerating electrons ballistically, or\ncoherently flipping the valley pseudospin. These dynamics leave unique\nsignatures, such as characteristic bandgaps or high-order harmonic radiation.\nThe fastest and least dissipative way of switching the technologically most\nimportant quantum attribute - the spin - between two states separated by a\npotential barrier is to trigger an all-coherent precession. Pioneering\nexperiments and theory with picosecond electric and magnetic fields have\nsuggested this possibility, yet observing the actual dynamics has remained out\nof reach. Here, we show that terahertz (1 THz = 10$^{12}$ Hz) electromagnetic\npulses allow coherent navigation of spins over a potential barrier and we\nreveal the corresponding temporal and spectral fingerprints. This goal is\nachieved by coupling spins in antiferromagnetic TmFeO$_{3}$ with the locally\nenhanced THz electric field of custom-tailored antennas. Within their duration\nof 1 ps, the intense THz pulses abruptly change the magnetic anisotropy and\ntrigger a large-amplitude ballistic spin motion. A characteristic phase flip,\nan asymmetric splitting of the magnon resonance, and a long-lived offset of the\nFaraday signal are hallmarks of coherent spin switching into adjacent potential\nminima, in agreement with a numerical simulation. The switchable spin states\ncan be selected by an external magnetic bias. The low dissipation and the\nantenna's sub-wavelength spatial definition could facilitate scalable spin\ndevices operating at THz rates.",
        "positive": "From zero resistance states to absolute negative conductivity in\n  microwave irradiated 2D electron systems: Recent experimental results regarding a 2D electron gas subjected to\nmicrowave radiation reveal that magnetoresistivity, apart from presenting\noscillations and zero resistance states, can evolve to negative values at\nminima. In other words, the current can evolve from flowing with no\ndissipation, to flow in the opposite direction of the dc bias applied. Here we\npresent a theoretical model in which the existence of radiation-induced\nabsolute negative conductivity is analyzed. Our model explains the transition\nfrom zero resistance states to absolute negative conductivity in terms of\nmultiphoton assisted electron scattering due to charged impurities. It shows as\nwell, how this transition can be driven by tuning microwave frequency and\nintensity. Then it opens the possibility of controlling the electron Larmor\norbits dynamics (magnetoconductivity) in microwave driven nanodevices. The\nanalysis of zero resistance states is therefore promising because new optical\nand transport properties in nanodevices will be expected."
    },
    {
        "anchor": "Artificial light and quantum order in systems of screened dipoles: The origin of light is a unsolved mystery in nature. Recently, it was\nsuggested that light may originate from a new kind of order - quantum order. To\ntest this idea in experiments, we study systems of screened magnetic/electric\ndipoles in 2D and 3D lattices. We show that our models contain an artificial\nlight -- a photon-like collective excitation. We discuss how to design\nrealistic devices that realize our models. We show that the ``speed of light''\nand the ``fine structure constant'' of the artificial light can be tuned in our\nmodels. The properties of artificial atoms (bound states of pairs of artificial\ncharges) are also discussed. The existence of artificial light (as well as\nartificial electron) in condensed matter systems suggests that elementary\nparticles, such as light and electron, may not be elementary. They may be\ncollective excitations of quantum order in our vacuum. Our models further\nsuggest that a gauge theory is a string-net theory in disguise. Light is a\nfluctuation of nets of large closed strings and charge is the end of open\nstrings.",
        "positive": "Negative frequency tuning of a carbon nanotube nano-electromechanical\n  resonator: A suspended, doubly clamped single wall carbon nanotube is characterized as\ndriven nano-electromechanical resonator at cryogenic temperatures.\nElectronically, the carbon nanotube displays small bandgap behaviour with\nCoulomb blockade oscillations in electron conduction and transparent contacts\nin hole conduction. We observe the driven mechanical resonance in dc-transport,\nincluding multiple higher harmonic responses. The data shows a distinct\nnegative frequency tuning at finite applied gate voltage, enabling us to\nelectrostatically decrease the resonance frequency to 75% of its maximum value.\nThis is consistently explained via electrostatic softening of the mechanical\nmode."
    },
    {
        "anchor": "Robustness and scalability of p-bits implemented with low energy barrier\n  nanomagnets: Probabilistic (p-) bits implemented with low energy barrier nanomagnets\n(LBMs) have recently gained attention because they can be leveraged to perform\nsome computational tasks very efficiently. Although more error-resilient than\nBoolean computing, p-bit based computing employing LBMs is, however, not\ncompletely immune to defects and device-to-device variations. In some tasks\n(e.g. binary stochastic neurons for machine learning and p-bits for population\ncoding), extended defects, such as variation of the LBM thickness over a\nsignificant fraction of the surface, can impair functionality. In this paper,\nwe have examined if unavoidable geometric device-to-device variations can have\na significant effect on one of the most critical requirements for probabilistic\ncomputing, namely the ability to \"program\" probability with an external agent,\nsuch as a spin-polarized current injected into the LBM. We found that the\nprogramming ability is fortunately not lost due to reasonable device-to-device\nvariations. The little variation in the probability versus current\ncharacteristic that reasonable device variability causes can be suppressed\nfurther by increasing the spin polarization of the current. This shows that\nprobabilistic computing with LBMs is robust against small geometric variations,\nand hence will be \"scalable\" to a large number of p-bits.",
        "positive": "Spin relaxation in the impurity band of a semiconductor in the external\n  magnetic field: Spin relaxation in the impurity band of a 2D semiconductor with spin-split\nspectrum in the external magnetic field is considered. Several mechanisms of\nspin relaxation are shown to be relevant. The first one is attributed to\nphonon-assisted transitions between Zeeman sublevels of the ground state of an\nisolated impurity, while other mechanisms can be described in terms of spin\nprecession in a random magnetic field during the electron motion over the\nimpurity band. In the later case there are two contributions to the spin\nrelaxation: the one given by optimal impurity configurations with the\nhop-waiting time inversely proportional to the external magnetic field and\nanother one related to the electron motion on a large scale. The average spin\nrelaxation rate is calculated."
    },
    {
        "anchor": "Frictional Transition from Superlubric Islands to Pinned Monolayers: The inertial sliding of physisorbed submonolayer islands on crystal surfaces\ncontains unexpected information on the exceptionally incommensurate smooth\nsliding state associated with superlubricity and on the mechanisms of its\ndisappearance. Here we show in a joint quartz crystal microbalance (QCM) and\nmolecular dynamics (MD) simulation case study of Xe on Cu(111) how\nsuperlubricity emerges in the large size limit of naturally incommensurate Xe\nislands. Theory also predicts, as coverage approaches a full monolayer, an\nabrupt adhesion-driven 2D density compression of order several %, implying here\na hysteretic jump from superlubric free islands to a pressurized commensurate\nimmobile monolayer. This scenario is fully supported by QCM data showing\nremarkably large slip times at increasing submonolayer coverages, signaling\nsuperlubricity, followed by a dramatic drop to zero for the dense commensurate\nmonolayer. Careful analysis of this variety of island sliding phenomena will be\nmandatory in future applications of friction of crystal-adsorbate interfaces.",
        "positive": "Determination of the sheet resistance of an infinite thin plate with\n  five point contacts located at arbitrary positions: In this paper, a five-probe method of sheet resistance measurement that is\nindependent of probe positions is reported. The method is strict for an\ninfinite homogeneous plane. It has potential applications as a sheet resistance\nstandard based on planar molecular layers. The method can be used to measure\nthe sheet resistance of layers covering objects with a spherical topology,\nparticularly on micro- and nanometric scales, where it is difficult to control\nprobe positioning."
    },
    {
        "anchor": "In-situ tuning of individual position-controlled nanowire quantum dots\n  via laser-induced intermixing: We demonstrate an in-situ technique to tune the emission energy of\nsemiconductor quantum dots. The technique is based on laser-induced atomic\nintermixing applied to nanowire quantum dots grown using a site-selective\nprocess that allows for the deterministic tuning of individual emitters. A\ntuning range of up to 15 meV is obtained with a precision limited by the laser\nexposure time. A distinct saturation of the energy shift is observed, which\nsuggests an intermixing mechanism relying on grown-in defects that are\nsubsequently removed from the semiconductor material during annealing. The\nability to tune different emitters into resonance with each other will be\nrequired for fabricating remote quantum dot-based sources of indistinguishable\nphotons for secure quantum networks.",
        "positive": "Visualizing structure of correlated ground states using collective\n  charge modes: The variety of correlated phenomena in moir\\'e systems is incredibly rich,\nspanning effects such as superconductivity, a generalized form of\nferromagnetism, or even charge fractionalization. This wide range of quantum\nphenomena is partly enabled by the large number of internal degrees of freedom\nin these systems, such as the valley and spin degrees of freedom, which\ninterplay decides the precise nature of the ground state. Identifying the\nmicroscopic nature of the correlated states in the moir\\'e systems is, however,\nchallenging, as it relies on interpreting transport behavior or\nscanning-tunneling microscopy measurements. Here we show how the real-space\nstructure of collective charge oscillations of the correlated orders can\ndirectly encode information about the structure of the correlated state,\nfocusing in particular on the problem of generalized Wigner crystals in moir\\'e\ntransition metal dichalcogenides. Our analysis builds upon our earlier result\n[10.1126/sciadv.adg3262] that the presence of a generalized Wigner crystal\nmodifies the plasmon spectrum of the system, giving rise to new collective\nmodes. We focus on scanning near-field optical microscopy technique (SNOM),\nfundamentally a charge-sensing-based method, and introduce a regime under which\nSNOM can operate as a probe of the spin degree of freedom."
    },
    {
        "anchor": "Undamped plasmon-polariton propagation along metallic nano-chain\n  including nonlinear effects: The nonlinear theory of collective plasmon-polariton propagation along the\ninfinite chain of metallic nanoparticles is developed within RPA quasiclassical\napproach to surface plasmons in large nano-spheres (10-50 nm for radius) of Au\nor Ag. The wave type self-modes in the chain are determined and analyzed with\nrespect to nano-sphere size and chain-separation parameters. At some regions\nfor parameters the undamped modes occur. They were found on the rim of\nstability within the linear theory. The nonlinear corrections stabilize,\nhowever, diverging modes of the linear approach and considerably enlarge the\nregion of undamped propagation. Nonlinearity is associated with relativistic\ncorrections to the Lorentz friction. According to the nonlinear behavior, the\nregion of parameters when undamped stable modes occur, covers the instability\nregion of the linear theory. The remarkable property of fixed amplitude of the\nundamped collective propagating wave independently of initial conditions (even\nif they are extremely small) has been identified and described. The group\nvelocity of this wave propagation is calculated.",
        "positive": "Effects of strong electron interactions and resonance scattering on\n  power output of nano-devices: We develop a Fermi-liquid based approach to investigate the power output of\nnano devices in the presence of strong interactions and resonance scattering.\nThe developed scheme is then employed to study the power output of a SU($N$)\nKondo impurity at the strong-coupling regime. The interplay between Kondo\nresonance and the filling-factors in the SU($N$) quantum systems is found to be\na key to enhance output power. Such enhancement results an output power\ncorresponding to $50\\%$ of the quantum upper bound. We demonstrate that given a\nproper tuning of the electron occupancy, the investigated power grows linearly\nwith degeneracy of Kondo state ($N$). This relation can hence be exploited to\nobtain output power that is larger than the one in existing non interacting\nsetups."
    },
    {
        "anchor": "Anisotropic magnetic responses of topological crystalline\n  superconductors: Majorana Kramers pairs emerged on surfaces of time-reversal-invariant\ntopological crystalline superconductors show the Ising anisotropy to an applied\nmagnetic field. We clarify that crystalline symmetry uniquely determines the\ndirection of the Majorana Ising spin for given irreducible representations of\npair potential, deriving constraints to topological invariants. Besides,\nnecessary conditions for nontrivial topological invariants protected by the\nn-fold rotational symmetry are shown.",
        "positive": "Spin transport properties of a quantum dot coupled to ferromagnetic\n  leads with noncollinear magnetizations: A correct general formula for the spin current through an interacting quantum\ndot coupled to ferromagnetic leads with magnetization at an arbitrary angle\n$\\theta$ is derived within the framework of the Keldysh formalism. Under\nasymmetric conditions, the spin current component J_{z} may change sign for\n$0<\\theta<\\pi$. It is shown that the spin current and spin tunneling\nmagnetoresistance exhibit different angle dependence in the free and Coulomb\nblockade regimes. In the latter case, the competition of spin precession and\nthe spin-valve effect could lead to an anomaly in the angle dependence of the\nspin current."
    },
    {
        "anchor": "Mesoscopic Josephson junctions with switchable current-phase relation: We propose and analyze a mesoscopic Josephson junction consisting of two\nferromagnetic insulator-superconductors (FI-Ss) coupled through a normal metal\n(N) layer. The Josephson current of the junction is non-trivially affected by\nthe spin-splitting field induced by the FIs in the two superconductors. In\nparticular, it shows sizeable enhancement by increasing the amplitude of the\nexchange field ($h_{ex}$) and displays a switchable current-phase relation\nwhich depends on the relative orientation of $h_{ex}$ in the FIs. In a\nrealistic EuS/Al-based setup this junction can be exploited as a\nhigh-resolution threshold sensor for the magnetic field as well as an on-demand\ntunable kinetic inductor.",
        "positive": "Impact ionization induced by terahertz radiation in HgTe quantum wells\n  of critical thickness: We report on the observation of terahertz (THz) radiation induced\nband-to-band impact ionization in \\HgTe quantum well (QW) structures of\ncritical thickness, which are characterized by a nearly linear energy\ndispersion. The THz electric field drives the carriers initializing\nelectron-hole pair generation. The carrier multiplication is observed for\nphoton energies less than the energy gap under the condition that the product\nof the radiation angular frequency $\\omega$ and momentum relaxation time\n$\\tau_{\\text l}$ larger than unity. In this case, the charge carriers acquire\nhigh energies solely because of collisions in the presence of a high-frequency\nelectric field. The developed microscopic theory shows that the probability of\nthe light impact ionization is proportional to $\\exp(-E_0^2/E^2)$, with the\nradiation electric field amplitude $E$ and the characteristic field parameter\n$E_0$. As observed in experiment, it exhibits a strong frequency dependence for\n$\\omega \\tau \\gg 1$ characterized by the characteristic field $E_0$ linearly\nincreasing with the radiation frequency $\\omega$."
    },
    {
        "anchor": "Conductance behavior in nanowires with spin-orbit interaction -- A\n  numerical study: We consider electronic transport through semiconducting nanowires (W) with\nspin-orbit interaction (SOI), in a hybrid N-W-N setup where the wire is\ncontacted by normal-metal leads (N). We investigate the conductance behavior of\nthe system as a function of gate and bias voltage, magnetic field, wire length,\ntemperature, and disorder. The transport calculations are performed numerically\nand are based on standard recursive Green's function techniques. In particular,\nwe are interested in understanding if and how it is possible to deduce the\nstrength of the SOI from the transport behavior. This is a very relevant\nquestion since so far no clear experimental observation in that direction has\nbeen produced. We find that the smoothness of the electrostatic potential\nprofile between the contacts and the wire plays a crucial role, and we show\nthat in realistic regimes the N-W-N setup may mask the effects of SOI, and a\ntrivial behavior with apparent vanishing SOI is observed. We identify an\noptimal parameter regime, with neither too smooth nor too abrupt potentials,\nwhere the signature of SOI is best visible, with and without Fabry-Perot\noscillations, and is most resilient to disorder and temperature effects.",
        "positive": "Aharonov-Bohm electron interferometer in the integer quantum Hall regime: We report experiments on a quantum electron interferometer fabricated from\nhigh mobility, low density GaAs/AlGaAs heterostructure material. In this\ndevice, a nearly circular electron island is defined by four front gates\ndeposited in etched trenches. The island is separated from the 2D electron bulk\nby two nearly open constrictions. In the quantum Hall regime, two\ncounterpropagating edge channels are coupled by tunneling in the constrictions,\nthus forming a closed electron interference path.For several fixed front gate\nvoltages, we observe periodic Aharonov-Bohm interference oscillations in\nfour-terminal resistance as a function of the enclosed flux. The oscillation\nperiod DeltaB gives the area of the interference path S via quantization\ncondition S=h/eDeltaB. We experimentally determine the dependence of S on the\nfront gate voltage, and find that the Aharonov-Bohm quantization condition does\nnot require significant corrections due to the confining potential. These\nresults can be interpreted as a constant integrated compressibility of the\nisland with respect to the front gates. We also analyze experimental results\nusing two classical electrostatics models: one modeling the 2D electron density\ndue to depletion from an etch trench, and another modeling the gate voltage\ndependence of the electron density profile in the island."
    },
    {
        "anchor": "The effect of the thermal reduction on the kinetics of low temperature\n  4He sorption and the structural characteristics of graphene oxide: The kinetics of the sorption and the subsequent desorption of 4He by the\nstarting graphite oxide (GtO) and the thermally reduced graphene oxide samples\n(TRGO, Treduction = 200, 300, 500, 700 and 900 C) have been investigated in the\ntemperature interval 1.5 - 20 K. The effect of the annealing temperature on the\nstructural characteristics of the samples was examined by the X-ray diffraction\n(XRD) technique. On lowering the temperature from 20 K to 11-12 K, the time of\n4He sorption increased for all the samples, which is typically observed under\nthe condition of thermally activated diffusion. Below 5 K the characteristic\ntimes of 4He sorption by the GtO and TRGO-200 samples were only weakly\ndependent on temperature, suggesting the dominance of the tunnel mechanism. In\nthe same region (T<5 K) the characteristic times of the TRGOs reduced at higher\ntemperatures (300, 500, 700 and 900 C) were growing with lowering temperature,\npresumably due to the defects generated in the carbon planes on removing the\noxygen functional groups (oFGs). The estimates of the activation energy (Ea) of\n4He diffusion show that in the TRGO-200 sample the Ea value is 2.9 times lower\nas compared to the parent GtO, which is accounted for by GtO exfoliation due to\nevaporation of the water intercalated in the interlayer space of carbon. The\nnonmonotonic dependences Ea vs T for the GtO samples treated above 200 C are\ndetermined by a competition between two processes - the recovery of the\ngraphite carbon structure, which increases the activation energy, and the\ngeneration of defects, which decreases the activation energy by opening\nadditional surface areas and ways for sorption. The dependence of the\nactivation energy on treatment temperature correlates well with the contents of\nthe crystalline phase in GtO varying with a rise of the annealing temperature.",
        "positive": "Microscopic theory of quantum dot interactions with quantum light: local\n  field effect: A theory of both linear and nonlinear electromagnetic response of a single QD\nexposed to quantum light, accounting the depolarization induced local--field\nhas been developed. Based on the microscopic Hamiltonian accounting for the\nelectron--hole exchange interaction, an effective two--body Hamiltonian has\nbeen derived and expressed in terms of the incident electric field, with a\nseparate term describing the QD depolarization. The quantum equations of motion\nhave been formulated and solved with the Hamiltonian for various types of the\nQD excitation, such as Fock qubit, coherent fields, vacuum state of\nelectromagnetic field and light with arbitrary photonic state distribution. For\na QD exposed to coherent light, we predict the appearance of two oscillatory\nregimes in the Rabi effect separated by the bifurcation. In the first regime,\nthe standard collapse--revivals phenomenon do not reveal itself and the QD\npopulation inversion is found to be negative, while in the second one, the\ncollapse--revivals picture is found to be strongly distorted as compared with\nthat predicted by the standard Jaynes-Cummings model. %The model developed can\neasily be extended to %%electromagnetic excitation. For the case of QD\ninteraction with arbitrary quantum light state in the linear regime, it has\nbeen shown that the local field induce a fine structure of the absorbtion\nspectrum. Instead of a single line with frequency corresponding to which the\nexciton transition frequency, a duplet is appeared with one component shifted\nby the amount of the local field coupling parameter. It has been demonstrated\nthe strong light--mater coupling regime arises in the weak-field limit. A\nphysical interpretation of the predicted effects has been proposed."
    },
    {
        "anchor": "Skyrmion lifetimes in ultrathin films: We show that thermal stability of magnetic skyrmions can be strongly affected\nby entropic effects. The lifetimes of isolated skyrmions in atomic Pd/Fe\nbilayers on Ir(111) and on Rh(111) are calculated in the framework of harmonic\ntransition state theory based on an atomistic spin model parametrized from\ndensity functional theory. Depending on the system the attempt frequency for\nskyrmion collapse can change by up to nine orders of magnitude with the\nstrength of the applied magnetic field. We demonstrate that this effect is due\nto a drastic change of entropy with skyrmion radius which opens a novel route\ntowards stabilizing sub-10 nm skyrmions at room temperature.",
        "positive": "Influence of Morphology on Blinking Mechanisms and Excitonic Fine\n  Structure of Single Colloidal Nanoplatelets: Colloidal semiconductor nanoplatelets (NPLs) with electronic structure as\nquantum wells have recently emerged as exciting materials for optoelectronic\napplications. Here we investigate how morphology affects important\nphotoluminescence (PL) properties of single CdSe and core/shell CdSe/CdZnS\nnanoplatelets. By analyzing PL intensity-lifetime correlation and second-order\nphoton correlation results, we demonstrate that, irrespective of morphology,\nAuger recombination cannot be responsible for PL blinking of single NPLs. We\npropose that hot carrier trapping plays a significant role in blinking and find\nthat a rough shell induces additional nonradiative channels presumably related\nto defects or traps of an imperfect shell. Polarization-resolved PL\nspectroscopy analysis reveals exciton fine-structure splitting on the order of\nseveral tens of meV in rough-shell NPLs at room temperature, which is\nattributed to exciton localization and substantiated with theoretical\ncalculations taking into account the NPL shape and electron-hole exchange\ninteraction."
    },
    {
        "anchor": "Photon-Induced Magnetization Reversal in Single-Molecule Magnets: We use millimeter wave radiation to manipulate the populations of the energy\nlevels of a single crystal molecular magnet Fe8. When a continuous wave\nradiation is in resonance with the transitions from the ground state to the\nfirst excited state, the equilibrium magnetization exhibits a dip. The position\nof this dip varies linearly with the radiation frequency. Our results provide a\nlower bound of 0.17 ns for transverse relaxation time and suggest the\npossibility that single-molecule magnets might be utilized for quantum\ncomputation.",
        "positive": "Confinement and Fermion Doubling Problem in Dirac-like Hamiltonians: We investigate the interplay between confinement and the fermion doubling\nproblem in Dirac-like Hamiltonians. Individually, both features are well known.\nFirst, simple electrostatic gates do not confine electrons due to the Klein\ntunneling. Second, a typical lattice discretization of the first-order\nderivative $k \\rightarrow -i\\partial_x$ skips the central point and allow\nspurious low-energy, highly oscillating solutions known as fermion doublers.\nWhile a no-go theorem states that the doublers cannot be eliminated without\nartificially breaking a symmetry, here we show that the symmetry broken by the\nWilson's mass approach is equivalent to the enforcement of hard-wall boundary\nconditions, thus making the no-go theorem irrelevant when confinement is\nforeseen. We illustrate our arguments by calculating the following: (i) the\nband structure and transport properties across thin films of the topological\ninsulator Bi$_2$Se$_3$, for which we use ab-initio density functional theory\ncalculations to justify the model; and (ii) the band structure of zigzag\ngraphene nanoribbons."
    },
    {
        "anchor": "Heat switch and thermoelectric effects based on Cooper-pair splitting\n  and elastic cotunneling: In this paper, we demonstrate that the hybrid normal-superconducting-normal\n(NSN) structure has potential for a multifunctional thermal device which could\nserve for heat flux control and cooling of microstructures. By adopting the\nscattering matrix approach, we theoretically investigate thermal and electrical\neffects emerging in such structures due to the Cooper pair splitting (CPS) and\nelastic cotunneling phenomena. We show that a finite superconductor can, in\nprinciple, mediate heat flow between normal leads, and we further clarify\nspecial cases when this seems contradictory to the second law of\nthermodynamics. Among other things, we demonstrate that the CPS phenomenon can\nappear even in the simple case of a ballistic NSN structure.",
        "positive": "Full counting statistics of chaotic cavities with many open channels: Explicit formulas are obtained for all moments and for all cumulants of the\nelectric current through a quantum chaotic cavity attached to two ideal leads,\nthus providing the full counting statistics for this type of system. The\napproach is based on random matrix theory, and is valid in the limit when both\nleads have many open channels. For an arbitrary number of open channels we\npresent the third cumulant and an example of non-linear statistics."
    },
    {
        "anchor": "Single spin magnetometry and relaxometry applied to antiferromagnetic\n  materials: Despite the considerable interest for antiferromagnets which appeared with\nthe perspective of using them for spintronics, their experimental study,\nincluding the imaging of antiferromagnetic textures, remains a challenge. To\naddress this issue, quantum sensors, and in particular the nitrogen-vacancy\n(NV) defects in diamond have become a widespread technical solution. We review\nhere the recent applications of single NV centers to study a large variety of\nantiferromagnetic materials, from quantitative imaging of antiferromagnetic\ndomains and non-collinear states, to the detection of spin waves confined in\nantiferromagnetic textures and the non-perturbative measurement of spin\ntransport properties. We conclude with recent developments improving further\nthe magnetic sensitivity of scanning NV microscopy, opening the way to detailed\ninvestigations of the internal texture of antiferromagnetic objects.",
        "positive": "Interplay between Zeeman interaction and spin-orbit coupling in a\n  two-dimensional semiconductor system: We analyse the interplay between Dresselhaus, Bychkov-Rashba, and Zeeman\ninteractions in a two-dimensional semiconductor quantum system under the action\nof a magnetic field. When a vertical magnetic field is considered, we predict\nthat the interplay results in an effective cyclotron frequency that depends on\na spin-dependent contribution. For in-plane magnetic fields, we found that the\ninterplay induces an anisotropic effective gyromagnetic factor that depends on\nthe orientation of the applied field as well as on the orientation of the\nelectron momentum."
    },
    {
        "anchor": "Tensile Strains Give Rise to Strong Size Effects for Thermal\n  Conductivities of Silicene, Germanene and Stanene: Based on first principles calculations and self-consistent solution of\nlinearized Boltzmann-Peierls equation for phonon transport approach within a\nthree-phonon scattering framework, we characterize lattice thermal\nconductivities k of freestanding silicene, germanene and stanene under\ndifferent isotropic tensile strains and temperatures. We find a strong size\ndependence of k for silicene with tensile strain, i.e., divergent k with\nincreasing system size, in contrast, the intrinsic room temperature k for\nunstrained silicene converges with system size to 19.34 W/m-K by 178 nm. The\nroom temperature k of strained silicene becomes as large as that of bulk\nsilicon by 84 um, indicating the possibility of using strain in silicene to\nmanipulate k for thermal management. The relative contribution to the intrinsic\nk from out-of-plane acoustic modes is largest for unstrained silicene, about\n39% at room temperature. The single mode relaxation time approximation, which\nworks reasonably well for bulk silicon, fails to appropriately describe phonon\nthermal transport in silicene, germanene and stanene within the temperature\nrange considered. For large samples of silicene, k increases with tensile\nstrain, peaks at about 7% strain and then decreases with further strain. In\ngermanene and stanene increasing strain hardens and stabilizes long wavelength\nout-of-plane acoustic phonons, and leads to similar k behaviors to those of\nsilicene. These findings further our understanding of phonon dynamics in\ngroup-IV buckled monolayers and may guide transfer and fabrication techniques\nof these freestanding samples and engineering k by size and strain for\napplications of thermal management and thermoelectricity.",
        "positive": "Surface roughness and thermal conductivity of semiconductor nanowires:\n  going below the Casimir limit: By explicitly considering surface roughness at the atomic level, we\nquantitatively show that the thermal conductivity of Si nanowires can be lower\nthan Casimir's classical limit. However, this violation only occurs for deep\nsurface degradation. For shallow surface roughness, the Casimir formula is\nshown to yield a good approximation to the phonon mean free paths and\nconductivity, even for nanowire diameters as thin as 2.22 nm. Our exact\ntreatment of roughness scattering is in stark contrast with a previously\nproposed perturbative approach, which is found to overpredict scattering rates\nby an order of magnitude. The obtained results suggest that a complete\ntheoretical understanding of some previously published experimental results is\nstill lacking."
    },
    {
        "anchor": "Nanosecond magnetization dynamics during spin Hall switching of in-plane\n  magnetic tunnel junctions: We present a study of the magnetic dynamics associated with nanosecond scale\nmagnetic switching driven by the spin Hall effect in 3-terminal nanoscale\nmagnetic tunnel junctions (3T-MTJs) with in-plane magnetization. Utilizing fast\npulse measurements in a variety of material stacks and detailed micromagnetic\nsimulations, we demonstrate that this unexpectedly fast and reliable magnetic\nreversal is facilitated by the self-generated Oersted field, and the\nshort-pulse energy efficiency can be substantially enhanced by micromagnetic\ncurvature in the magnetic free layer. The sign of the Oersted field is\nessential for this enhancement --- in simulations in which we artificially\nimpose a field-like torque with a sign opposite to the effect of the Oersted\nfield, the result is a much slower and stochastic switching process that is\nreminiscent of the so-called incubation delay in conventional 2-terminal\nspin-torque-switched MTJs.",
        "positive": "Statistical thermodynamics of the diced lattice: In this work we analyze the statistical thermodynamics of Diced lattice\ncarriers employing a Greens function formulation to examine the grand\npotential, Helmholtz free energy, the grand and ordinary partition functions\nand entropy. This facilitates the calculation of the specific heat, and all\nevaluations are carried out for both the degenerate and nondegenerate\nstatistical regimes."
    },
    {
        "anchor": "Local and Tunable Geometric Phase of Dirac Fermions in a Topological\n  Junction: We discover a new type of geometric phase of Dirac fermions in solids, which\nis an electronic analogue of the Pancharatnam phase of polarized light. The\ngeometric phase occurs in a local and nonadiabatic scattering event of Dirac\nfermions at a junction, unveiling topological aspects of scattering of chiral\nparticles, and it is experimentally tunable to an arbitrary value. It provides\na unique approach of detecting the topological order of the insulator in a\nmetal-insulator junction of Dirac fermions, establishing new bulk-edge\ncorrespondence. The geometric phase also modifies the fundamental quantization\nrule of Dirac fermions, suggesting topological devices with nontrivial charge\nand spin transport such as a topological wave guide and a topological\ntransistor.",
        "positive": "Terahertz Time-Domain Magnetospectroscopy of a High-Mobility\n  Two-Dimensional Electron Gas: We have observed cyclotron resonance in a high-mobility GaAs/AlGaAs\ntwo-dimensional electron gas by using the techniques of terahertz time-domain\nspectroscopy combined with magnetic fields. From this, we calculate the real\nand imaginary parts of the diagonal elements of the magnetoconductivity tensor,\nwhich in turn allows us to extract the concentration, effective mass, and\nscattering time of the electrons in the sample. We demonstrate the utility of\nultrafast terahertz spectroscopy, which can recover the true linewidth of\ncyclotron resonance in a high-mobility ($>{10}^{6} \\mathrm{cm^{2} V^{-1}\ns^{-1}}$) sample without being affected by the saturation effect."
    },
    {
        "anchor": "Quantum Hall wave functions on the torus: We present explicit expressions for a large set of hierarchy wave functions\non the torus. Included are the Laughlin states, the states in the positive Jain\nseries, and recently observed states at e.g. $\\nu = 4/11$. The techniques we\nuse constitute a nontrivial extension of the conformal field theory methods\ndeveloped earlier to construct the corresponding wave functions in disc\ngeometry.",
        "positive": "Optical Conductivity Signatures of Floquet Electronic Phases: Optical conductivity measurements may provide access to distinct signatures\nof Floquet electronic phases, which are described theoretically by their\nquasienergy band structures. We characterize experimental observables of the\nFloquet graphene antidot lattice (FGAL), which we introduced previously [Phys.\nRev. B 104, 174304 (2021)]. On the basis of Floquet linear response theory, the\nreal and imaginary parts of the longitudinal and Hall optical conductivity are\ncomputed as a function of probe frequency. We find that the number and\npositions of peaks in the response function are distinctive of the different\nFloquet electronic phases, and identify multiple properties with no equilibrium\nanalog. First, for several intervals of probe frequencies, the real part of the\nconductivity becomes negative. We argue this is indicative of a subversion of\nthe usual Joule heating mechanism: The Floquet drive causes the material to\namplify the power of the probe, resulting in gain. Additionally, while the Hall\nresponse vanishes at equilibrium, the real and imaginary parts of the Floquet\nHall conductivity are non-zero and can be as large as the longitudinal\ncomponents. Lastly, driving-induced localization tends to reduce the overall\nmagnitude of and to flatten out the optical conductivity signal. From an\nimplementation standpoint, a major advantage of the FGAL is that the\nabove-bandwidth driving limit is reached with photon energies that are at least\ntwenty times lower than that required for the intrinsic material, allowing for\nsignificant band renormalization at orders-of-magnitude smaller intensities.\nOur work provides the necessary tools for experimentalists to map reflectance\ndata to particular Floquet phases for this novel material."
    },
    {
        "anchor": "Tuning proximity spin-orbit coupling in graphene/NbSe$_2$\n  heterostructures via twist angle: We investigate the effect of the twist angle on the proximity spin-orbit\ncoupling (SOC) in graphene/NbSe$_2$ heterostructures from first principles. The\nlow-energy Dirac bands of several different commensurate twisted supercells are\nfitted to a model Hamiltonian, allowing us to study the twist-angle dependency\nof the SOC in detail. We predict that the magnitude of the Rashba SOC can\ntriple, when going from $\\Theta=0^\\circ$ to $\\Theta=30^\\circ$ twist angle.\nFurthermore, at a twist angle of $\\Theta\\approx23^\\circ$ the in-plane spin\ntexture acquires a large radial component, corresponding to a Rashba angle of\nup to $\\Phi=25^\\circ$. The twist-angle dependence of the extracted proximity\nSOC is explained by analyzing the orbital decomposition of the Dirac states to\nreveal with which NbSe$_2$ bands they hybridize strongest. Finally, we employ a\nKubo formula to evaluate the efficiency of conventional and unconventional\ncharge-to-spin conversion in the studied heterostructures.",
        "positive": "Quantized Conductance and Switching in Percolating Nanoparticle Films: We demonstrate switching behavior and quantized conductance at room\ntemperature in percolating films of nanoparticles. Our experiments and\ncomplementary simulations show that switching and quantization result from\nformation of atomic scale wires in gaps between particles. These effects occur\nonly when tunnel gaps are present in the film, close to the percolation\nthreshold."
    },
    {
        "anchor": "Conductance plateau in quantum spin transport through an interacting\n  quantum dot: Quantum spin transport is studied in an interacting quantum dot. It is found\nthat a conductance \"plateau\" emerges in the non-linear charge conductance by a\nspin bias in the Kondo regime. The conductance plateau, as a complementary to\nthe Kondo peak, originates from the strong electron correlation and exchange\nprocesses in the quantum dot, and can be regarded as one of the characteristics\nin quantum spin transport.",
        "positive": "Shared control of a 16 semiconductor quantum dot crossbar array: The efficient control of a large number of qubits is one of most challenging\naspects for practical quantum computing. Current approaches in solid-state\nquantum technology are based on brute-force methods, where each and every qubit\nrequires at least one unique control line, an approach that will become\nunsustainable when scaling to the required millions of qubits. Here, inspired\nby random access architectures in classical electronics, we introduce the\nshared control of semiconductor quantum dots to efficiently operate a\ntwo-dimensional crossbar array in planar germanium. We tune the entire array,\ncomprising 16 quantum dots, to the few-hole regime and, to isolate an unpaired\nspin per dot, we confine an odd number of holes in each site. Moving forward,\nwe establish a method for the selective control of the quantum dots interdot\ncoupling and achieve a tunnel coupling tunability over more than 10 GHz. The\noperation of a quantum electronic device with fewer control terminals than\ntunable experimental parameters represents a compelling step forward in the\nconstruction of scalable quantum technology."
    },
    {
        "anchor": "A Fitting Model for Asymmetric I-V Characteristics of Graphene\n  Field-Effect Transistors for Extraction of Intrinsic Mobilities: A fitting model is developed for accounting the asymmetric ambipolarities in\nthe I-V characteristics of graphene field-effect transistors (G-FETs) with\ndoped channels, originating from the thermionic emission and interband\ntunneling at the junctions between the gated and access regions. Using the\nmodel, the gate-voltage-dependent intrinsic mobility as well as other intrinsic\nand extrinsic device parameters can be extracted. We apply it to a top-gated\nG-FET with a graphene channel grown on a SiC substrate and with SiN gate\ndielectric that we reported previously, and we demonstrate that it can\nexcellently fit its asymmetric I-V characteristic.",
        "positive": "Discovery of intrinsic ferromagnetism in 2D van der Waals crystals: It has been long hoped that the realization of long-range ferromagnetic order\nin two-dimensional (2D) van der Waals (vdW) crystals, combined with their rich\nelectronic and optical properties, would open up new possibilities for\nmagnetic, magnetoelectric and magneto-optic applications. However, in 2D\nsystems, the long-range magnetic order is strongly hampered by thermal\nfluctuations which may be counteracted by magnetic anisotropy, according to the\nMermin-Wagner theorem. Prior efforts via defect and composition engineering,\nand proximity effect only locally or extrinsically introduce magnetic\nresponses. Here we report the first experimental discovery of intrinsic\nlong-range ferromagnetic order in pristine Cr2Ge2Te6 atomic layers by scanning\nmagneto-optic Kerr microscopy. In such a 2D vdW soft ferromagnet, for the first\ntime, an unprecedented control of transition temperature of ~ 35% - 57%\nenhancement is realized via surprisingly small fields (<= 0.3 Tesla in this\nwork), in stark contrast to the stiffness of the transition temperature to\nmagnetic fields in the three-dimensional regime. We found that the small\napplied field enables an effective anisotropy far surpassing the tiny\nmagnetocrystalline anisotropy, opening up a sizable spin wave excitation gap.\nConfirmed by renormalized spin wave theory, we explain the phenomenon and\nconclude that the unusual field dependence of transition temperature\nconstitutes a hallmark of 2D soft ferromagnetic vdW crystals. Our discovery of\n2D soft ferromagnetic Cr2Ge2Te6 presents a close-to-ideal 2D Heisenberg\nferromagnet for studying fundamental spin behaviors, and opens the door for\nexploring new applications such as ultra-compact spintronics."
    },
    {
        "anchor": "Quantum kinetic equations for the ultrafast spin dynamics of excitons in\n  diluted magnetic semiconductor quantum wells after optical excitation: Quantum kinetic equations of motion for the description of the exciton spin\ndynamics in II-VI diluted magnetic semiconductor quantum wells with laser\ndriving are derived. The model includes the magnetic as well as the nonmagnetic\ncarrier-impurity interaction, the Coulomb interaction, Zeeman terms, and the\nlight-matter coupling, allowing for an explicit treatment of arbitrary\nexcitation pulses. Based on a dynamics-controlled truncation scheme,\ncontributions to the equations of motion up to second order in the generating\nlaser field are taken into account. The correlations between the carrier and\nthe impurity subsystems are treated within the framework of a correlation\nexpansion. For vanishing magnetic field, the Markov limit of the quantum\nkinetic equations formulated in the exciton basis agrees with existing theories\nbased on Fermi's golden rule. For narrow quantum wells excited at the $1s$\nexciton resonance, numerical quantum kinetic simulations reveal pronounced\ndeviations from the Markovian behavior. In particular, the spin decays\ninitially with approximately half the Markovian rate and a non-monotonic decay\nin the form of an overshoot of up to $10\\,\\%$ of the initial spin polarization\nis predicted.",
        "positive": "Topological states and braiding statistics using quantum circuits: Using superconducting quantum circuits, we propose an approach to construct a\nKitaev lattice, i.e., an anisotropic spin model on a honeycomb lattice with\nthree types of nearest-neighbor interactions. We study two particular cases to\ndemonstrate topological states (i.e., the vortex and bond states) and show how\nthe braiding statistics can be revealed. Our approach provides an\nexperimentally realizable many-body system for demonstrating exotic properties\nof topological phases."
    },
    {
        "anchor": "Resonant scattering in a strong magnetic field: exact density of states: We study the structure of 2D electronic states in a strong magnetic field in\nthe presence of a large number of resonant scatterers. For an electron in the\nlowest Landau level, we derive the exact density of states by mapping the\nproblem onto a zero-dimensional field-theoretical model. We demonstrate that\nthe interplay between resonant and non-resonant scattering leads to a\nnon-analytic energy dependence of the electron Green function. In particular,\nfor strong resonant scattering the density of states develops a gap in a finite\nenergy interval. The shape of the Landau level is shown to be very sensitive to\nthe distribution of resonant scatterers.",
        "positive": "The quest for Casimir repulsion between Chern-Simons surfaces: In this paper we critically reconsider the Casimir repulsion between surfaces\nthat carry the Chern-Simons interaction (corresponding to the Hall type\nconductivity). We present a derivation of the Lifshitz formula valid for\narbitrary planar geometries and discuss its properties. This analysis allows us\nto resolve some contradictions in the previous literature. We compute the\nCasimir energy for two surfaces that have constant longitudinal and Hall\nconductivities. The repulsion is possible only if both surfaces have Hall\nconductivities of the same sign. However, there is a critical value of the\nlongitudinal conductivity above which the repulsion disappears. We also\nconsider a model where both parity odd and parity even terms in the\nconductivity are produced by the polarization tensor of surface modes. In\ncontrast to the previous publications L. Chen and S.-L. Wan, Phys. Rev. B84,\n075149 (2011); B85, 115102 (2012), we include the parity anomaly term. This\nterm ensures that the conductivities vanish for infinitely massive surface\nmodes. We find that at least for a single mode regardless of the sign and value\nof its mass, there is no Casimir repulsion."
    },
    {
        "anchor": "Effect of Exchange-type Zero-bias Anomaly on Single Electron Tunnelling\n  of Au Nanoparticles: Using cryogenic scanning tunnelling microscopy and scanning tunnelling\nspectroscopy we measured single electron tunnelling of isolated Au\nnanoparticles with 1.4 nm in radius. We observe that a gap {\\Delta}V ~ 2e/C (C\nis the capacitance of the Au particle) around zero bias in the tunnelling\nconductance spectrum, followed by a series of discrete single electron\ntunnelling peaks with voltage widths of EC ~ e/C at both negative and positive\nbias. Experimental data are well explained by taking into account the effect of\nexchange interaction of electrons on the single electron tunnelling of Au\nnanoparticles. A tunnelling peak near zero-bias was suppressed by the\nexchange-type zero-bias anomaly, which results in the gap {\\Delta}V ~ 2EC.",
        "positive": "Control of single photon emitters in semiconductor nanowires by surface\n  acoustic waves: We report on experimental study into the effects of surface acoustic waves on\nthe optical emission of dot-in-a-nanowire heterostructures in III-V material\nsystems. Under direct optical excitation, the excitonic energy levels in\nIII-nitride dot-in-a-nanowire heterostructures oscillate at the acoustic\nfrequency, producing a characteristic splitting of the emission lines in the\ntime-integrated photoluminescence spectra. This acoustically induced periodic\ntuning of the excitonic transition energies is combined with spectral detection\nfiltering and employed as a tool to regulate the temporal output of\nanti-bunched photons emitted from these nanowire quantum dots. In addition, the\nacoustic transport of electrons and holes along a III-arsenide nanowire injects\nthe electric charges into an ensemble of quantum dot-like recombination centers\nthat are spatially separated from the optical excitation area. The acoustic\npopulation and depopulation mechanism determines the number of carrier\nrecombination events taking place simultaneously in the ensemble, thus allowing\na control of the anti-bunching degree of the emitted photons. The present\nresults are relevant for the dynamic control of single photon emission in III-V\nsemiconductor heterostructures."
    },
    {
        "anchor": "Topological conditions for impurity effects in graphene nanosystems: We consider electronic spectra of graphene nanotubes and their perturbation\nby impurity atoms absorbed at different positions on nanotube surfaces, within\nthe framework of Anderson hybrid model. A special attention is given to the\ncases when Dirac-like 1D modes appear in the nanotube spectrum and their\nhybridization with localized impurity states produces, at growing impurity\nconcentration $c$, onset of a mobility gap near the impurity level and even\nopening, at yet higher $c$, of some narrow delocalized range within this\nmobility gap. Such behaviors are compared with the similar effects in the\npreviously studied 2D graphene and armchair type graphene nanoribbons. Some\npossible practical applications are discussed.",
        "positive": "Viscous dynamics of vortices in a ferromagnetic film: We derive viscous forces for vortices in a thin-film ferromagnet. The viscous\nforce acting on vortex $i$ is a linear superposition $\\mathbf F_i = - \\sum_{j}\n\\hat{D}_{ij} \\mathbf V_j$, where $\\mathbf V_j$ is the velocity of vortex $j$.\nThanks to the long-range nature of vortices, the mutual drag tensor\n$\\hat{D}_{ij}$ is comparable in magnitude to the coefficient of self-drag\n$D_{ii}$."
    },
    {
        "anchor": "Random-phase reservoir and a quantum resistor: The Lloyd model: We introduce phase disorder in a 1D quantum resistor through the formal\ndevice of `fake channels' distributed uniformly over its length such that the\nout-coupled wave amplitude is re-injected back into the system, but with a\nphase which is random. The associated scattering problem is treated via\ninvariant imbedding in the continuum limit, and the resulting transport\nequation is found to correspond exactly to the Lloyd model. The latter has been\na subject of much interest in recent years. This conversion of the random phase\ninto the random Cauchy potential is a notable feature of our work. It is\nfurther argued that our phase-randomizing reservoir, as distinct from the well\nknown phase-breaking reservoirs, induces no decoherence, but essentially\ndestroys all interference effects other than the coherent back scattering.",
        "positive": "Negative Full Counting Statistics Arise From Interference Effects: The Keldysh-ordered full counting statistics is a quasi-probability\ndistribution describing the fluctuations of a time-integrated quantum\nobservable. While it is well known that this distribution can fail to be\npositive, the interpretation and origin of this negativity has been somewhat\nunclear. Here, we show how the full counting statistics can be tied to\ntrajectories through Hilbert space, and how this directly connects negative\nquasi-probabilities to an unusual interference effect. Our findings are\nillustrated with the example of energy fluctuations in a driven bosonic\nresonator; we discuss how negative quasi-probability here could be detected\nexperimentally using superconducting microwave circuits."
    },
    {
        "anchor": "Enhancement of perpendicular magnetic anisotropy and\n  Dzyaloshinskii-Moriya interaction in thin ferromagnetic films by atomic-scale\n  modulation of interfaces: To stabilize the non-trivial spin textures, e.g., skyrmions or chiral domain\nwalls in ultrathin magnetic films, an additional degree of freedom such as the\ninterfacial Dzyaloshinskii-Moriya interaction (IDMI) must be induced by the\nstrong spin-orbit coupling (SOC) of a stacked heavy metal layer. However,\nadvanced approaches to simultaneously control IDMI and perpendicular magnetic\nanisotropy (PMA) are needed for future spin-orbitronic device implementations.\nHere, we show an effect of atomic-scale surface modulation on the magnetic\nproperties and IDMI in ultrathin films composed of 5d heavy\nmetal/ferromagnet/4d(5d) heavy metal or oxide interfaces, such as\nPt/CoFeSiB/Ru, Pt/CoFeSiB/Ta, and Pt/CoFeSiB/MgO. The maximum IDMI value\ncorresponds to the correlated roughness of the bottom and top interfaces of the\nferromagnetic layer. The proposed approach for significant enhancement of PMA\nand IDMI through the interface roughness engineering at the atomic scale offers\na powerful tool for the development of the spin-orbitronic devices with the\nprecise and reliable controllability of their functionality.",
        "positive": "Spintronics-based mesoscopic heat engine: We consider a nanowire suspended on two spin-polarized leads and subject to a\nnonuniform magnetic field. We show that in such a system a temperature drop\nbetween leads can significantly affect the nanowire dynamics. In particular, it\nis demonstrated that under certain conditions the stationary distribution of\nthe mechanical subsystem has Boltzmann form with effective temperature which is\nsmaller than the temperature of the \"cold\" lead; this seems rather\ncounterintuitive. We also find that the change of the direction of the\ntemperature gradient results in generation of mechanical vibrations rather than\nheating of the mechanical subsystem."
    },
    {
        "anchor": "Inducing room-temperature valley polarization of excitonic emission in\n  transition metal dichalcogenide monolayers: The lowest energy states in transition metal dichalcogenide (TMD) monolayers\nfollow valley selection rules, which have attracted vast interest due to the\npossibility of encoding and processing of quantum information. However, these\nquantum states are strongly affected by the temperature-dependent intervalley\nscattering causing complete valley depolarization, which is hampering any\npractical applications of TMD monolayers at room temperature. Therefore, for\nachieving clear and robust valley polarization in TMD monolayers one needs to\nsuppress parasitic depolarization processes, which is the central challenge in\nthe growing field of valleytronics. Here, in electron-doping experiments on TMD\nmonolayers, we demonstrate that strong doping levels beyond $10^{13}$~cm$^{-2}$\ncan induce 61\\% and 37\\% valley contrast at room temperature in tungsten\ndiselenide and molybdenum diselenide monolayers, respectively. Our results\nindicate that charged excitons in TMD monolayers can be utilized as quantum\nunits in designing of practical valleytronic devices operating at 300 K.",
        "positive": "Non-Hermitian tearing by dissipation: In the paper, we study the non-Hermitian system under dissipation, where the\nenergy band shows an imaginary line gap and energy eigenstates are bound to a\nspecific region. To describe these phenomena, we propose the concept of\n\"non-Hermitian tearing\" in which the tearability we define reveals a continuous\nphase transition at the exceptional point. The non-Hermitian tearing manifests\nin two forms -- bulk state separation and boundary state decoupling. For a\ndeeper understanding of non-Hermitian tearing, we give the effective 2*2\nHamiltonian in the k-space by reducing the N*N Hamiltonian in the real space.\nIn addition, we also explore the non-Hermitian tearing in the one-dimensional\nSu-Schrieffer-Heeger model and the Qi-Wu-Zhang model. Our results provide a\ntheoretical approach for studying non-Hermitian tearing in more complex\nsystems."
    },
    {
        "anchor": "Hot exciton relaxation in coupled ultra-thin CdTe/ZnTe quantum well\n  structures: The photoluminescence (PL) and PL excitation (PLE) spectra of CdTe/ZnTe\nasymmetric double quantum well (QW) structures are studied on a series of\nsamples containing two CdTe layers with nominal thicknesses of 2 and 4\nmonolayers (ML) in the ZnTe matrix. The samples differ in the thickness of the\nZnTe spacer between CdTe QWs which is 45, 65 and 75 ML. It has been found that\nat above-barrier excitation the PL from a shallow QW at sufficiently weak\nexcitation intensities is determined by recombination of hot excitons. It is\nshown that under these conditions, when PL is excited by lasers with different\nwavelengths, the ratio of the PL intensities from shallow and deep QWs\ndecreases exponentially with an increase of the initial kinetic energy of hot\nexcitons. It is found that energy relaxation of hot excitons with LO phonon\nemission determine the shape of the PLE spectrum of shallow QW in the range of\nexciton kinetic energies up to more than 20 LO phonons above ZnTe bandgap. We\nhave shown that the results obtained are well described by the model of charge\nand energy transfer between QWs.",
        "positive": "Majorana Fermion Induced Non-local Current Correlations in Spin-orbit\n  Coupled Superconducting Wires: Recent observation of zero bias conductance peaks in semiconductor\nwire/superconductor heterostructures has generated great interest, and there is\na hot debate on whether the observation is associated with Majorana fermions\n(MFs). Here we study the local and crossed Andreev reflections in a junction of\ntwo normal leads and a sandwiched superconductor-semiconductor wire with two\nspatially separated but strongly coupled MF end states. The conductance and\nFano factors of such a device are sharply different from the topologically\ntrivial case even in the presence of disorder, and can hence be used to\nidentify MFs unambiguously."
    },
    {
        "anchor": "Electrical switching of an antiferromagnet: Louis Neel pointed out in his Nobel lecture that while abundant and\ninteresting from a theoretical viewpoint, antiferromagnets did not seem to have\nany applications. Indeed, the alternating directions of magnetic moments on\nindividual atoms and the resulting zero net magnetization make antiferromagnets\nhard to control by tools common in ferromagnets. Remarkably, Neel in his\nlecture provides the key which, as we show here, allows us to control\nantiferromagnets by electrical means analogous to those which paved the way to\nthe development of ferromagnetic spintronics applications. The key noted by\nNeel is the equivalence of antiferromagnets and ferromagnets for effects that\nare an even function of the magnetic moment. Based on even-in-moment\nrelativistic transport phenomena, we demonstrate room-temperature electrical\nswitching between two stable configurations combined with electrical read-out\nin antiferromagnetic CuMnAs thin film devices. Our magnetic memory is\ninsensitive to and produces no magnetic field perturbations which illustrates\nthe unique merits of antiferromagnets for spintronics.",
        "positive": "Inherent fluctuation-mediated equivalent force drives directional\n  motions of nanoscale asymmetric particles -- Surf-riding of asymmetric\n  molecules in thermal fluctuations: Using a simple theoretical model of a nanoscale asymmetric particle/molecule\nwith asymmetric structure or/and asymmetric charge distribution, here using a\ncharge dipole as an example, we show that there is unidirectional\ntransportation mediated by non-white fluctuations if the asymmetric orientation\nof the particle/molecule is constrained. This indicates the existence of an\ninherent equivalent force, which drives the particle/molecule itself along the\norientation of the asymmetric particle in the environment of fluctuations. In\npractical systems, equivalent force also exist in the asymmetric molecules,\nsuch as water and ethanol, at the ambient condition since thermal fluctuations\nare not white anymore at nanoscale [Wan, R., J. Hu, and H. Fang, Sci. China\nPhys. Mech. Astron. 2012, 55, 751]. Molecular dynamic simulations show that\nthere is unidirectional transportation of an ultrathin water layer on solid\nsurface at room temperature when the orientations of water molecules have a\npreference. The finding will play an essential role in the understanding of the\nworld from a molecular view and the developing of novel technology for various\nnanoscale and bulk applications, such as chemical separation, water treatment,\nsensing and drug delivery."
    },
    {
        "anchor": "Correcting for Bias of Molecular Confinement Parameters Induced by Small\n  Time Series Sample Sizes in Single-Molecule Trajectories Containing\n  Measurement Noise: Several single-molecule studies aim to reliably extract parameters\ncharacterizing molecular confinement or transient kinetic trapping from\nexperimental observations. Pioneering works from single particle tracking in\nmembrane diffusion studies [Kusumi et al., Biophysical J., 1993] appealed to\nMean Square Displacement tools for extracting diffusivity and other parameters\nquantifying the degree of confinement. More recently, the practical utility of\nsystematically treating multiple noise sources (including noise induced by\nrandom photon counts) through likelihood techniques have been more broadly\nrealized in the SPT community. However, bias induced by finite time series\nsample sizes has not received great attention. Mitigating parameter bias\ninduced by finite sampling is important to any scientific endeavor aiming for\nhigh accuracy, but correcting for bias is also often an important step in the\nconstruction of optimal parameter estimates. In this article, it is\ndemonstrated how a popular model of confinement can be corrected for finite\nsample bias in situations where the underlying data exhibits Brownian diffusion\nand observations are measured with non-negligible experimental noise (e.g.,\nnoise induced by finite photon counts). The work of Tang and Chen [J.\nEconometrics, 2009] is extended to correct for bias in the estimated corral\nradius (a parameter commonly used to quantify confinement in SPT studies) in\nthe presence of measurement noise. It is shown that the approach presented is\ncapable of reliably extracting the corral radius using only hundreds of\ndiscretely sampled observations in situations where other methods (including\nMSD and Bayesian techniques) would encounter serious difficulties. The ability\nto accurately statistically characterize transient confinement suggests new\ntechniques for quantifying confined and/or hop diffusion in complex\nenvironments.",
        "positive": "Spin-orbital magnetic response of relativistic fermions with band\n  hybridization: Spins of relativistic fermions are related to their orbital degrees of\nfreedom. In order to quantify the effect of hybridization between relativistic\nand nonrelativistic degrees of freedom on spin-orbit coupling, we focus on the\nspin-orbital (SO) crossed susceptibility arising from spin-orbit coupling. The\nSO crossed susceptibility is defined as the response function of their spin\npolarization to the \"orbital\" magnetic field, namely the effect of magnetic\nfield on the orbital motion of particles as the vector potential. Once\nrelativistic and nonrelativistic fermions are hybridized, their SO crossed\nsusceptibility gets modified at the Fermi energy around the band hybridization\npoint, leading to spin polarization of nonrelativistic fermions as well. These\neffects are enhanced under a dynamical magnetic field that violates thermal\nequilibrium, arising from the interband process permitted by the band\nhybridization. Its experimental realization is discussed for Dirac electrons in\nsolids with slight breaking of crystalline symmetry or doping, and also for\nquark matter including dilute heavy quarks strongly hybridized with light\nquarks, arising in a relativistic heavy-ion collision process."
    },
    {
        "anchor": "A Composite Fermion Hofstader Problem: Partially Polarized Density Wave\n  States in the 2/5 FQHE: It is well-known that the 2/5 state is unpolarized at zero Zeeman energy,\nwhile it is fully polarized at large Zeeman energies. A novel state with\ncharge/spin density wave order for Composite Fermions is proposed to exist at\nintermediate values of the Zeeman coupling for 2/5. This state has half the\nmaximum possible polarization, and can be extended to other incompressible\nfractions. A Hartree-Fock calculation based on the new approach for all\nfractional quantum Hall states developed by R.Shankar and the author is used to\ndemonstrate the stability of this state to single-particle excitations, and\ncompute gaps. We compare our results with a very recent experiment which shows\ndirect evidence for the existence of such a state, and also with more indirect\nevidence from past experiments.",
        "positive": "Theoretical and Experimental Studies of Schottky Diodes That Use Aligned\n  Arrays of Single Walled Carbon Nanotubes: We present theoretical and experimental studies of Schottky diodes that use\naligned arrays of single walled carbon nanotubes. A simple physical model,\ntaking into account the basic physics of current rectification, can adequately\ndescribe the single-tube and array devices. We show that for as grown array\ndiodes, the rectification ratio, defined by the\nmaximum-to-minimum-current-ratio, is low due to the presence of m-SWNT shunts.\nThese tubes can be eliminated in a single voltage sweep resulting in a high\nrectification array device. Further analysis also shows that the channel\nresistance, and not the intrinsic nanotube diode properties, limits the\nrectification in devices with channel length up to ten micrometer."
    },
    {
        "anchor": "Bright visible light emission from graphene: Graphene and related two-dimensional materials are promising candidates for\natomically thin, flexible, and transparent optoelectronics. In particular, the\nstrong light-matter interaction in graphene has allowed for the development of\nstate-of-the-art photodetectors, optical modulators, and plasmonic devices. In\naddition, electrically biased graphene on SiO2 substrates can be used as a\nlow-efficiency emitter in the mid-infrared range. However, emission in the\nvisible range has remained elusive. Here we report the observation of bright\nvisible-light emission from electrically biased suspended graphenes. In these\ndevices, heat transport is greatly minimised; thus hot electrons (~ 2800 K)\nbecome spatially localised at the centre of graphene layer, resulting in a\n1000-fold enhancement in the thermal radiation efficiency. Moreover, strong\noptical interference between the suspended graphene and substrate can be\nutilized to tune the emission spectrum. We also demonstrate the scalability of\nthis technique by realizing arrays of chemical-vapour-deposited graphene bright\nvisible-light emitters. These results pave the way towards the realisation of\ncommercially viable large-scale, atomically-thin, flexible and transparent\nlight emitters and displays with low-operation voltage, and graphene-based,\non-chip ultrafast optical communications.",
        "positive": "Local Temperatures and Heat Flow in Quantum Driven Systems: We discuss the concept of local temperature for quantum systems driven out of\nequilibrium by ac pumps showing explicitly that it is the correct indicator for\nheat flow. We also show that its use allows for a generalization of the\nWiedemann Franz law."
    },
    {
        "anchor": "The Role of Geometry in Tailoring the Linear and Nonlinear Optical\n  Properties of Semiconductor Quantum Dots: The paper aims to reveal the relationship between the geometrical features\nand linear and nonlinear optical properties of InAs quantum dots (QDs). This\nproblem is justified by the extreme variety offered by the recent advances in\ngrowth techniques tailored to the attainment of QDs and nanostructures with\nvirtually any shape. To that end, the Finite Element Method in conjunction with\nthe Effective Mass Approximation and Envelope Function Approximation was\nemployed to solve the one-particle eigenproblems in domains with any complex\ngeometries. The paper explores nanoplatelets, spherical QDs, nanocones,\nnanorods, nanotadpoles, and nanostars. It has been found that there is a clear\ncorrelation between the complexity and symmetry of the QDs and their linear and\nnonlinear absorption spectra for transitions between the electronic ground\nstate and the first three excited states.",
        "positive": "Spectral butterfly and electronic localization in rippled-graphene\n  nanorribons: mapping onto effective one-dimensional chains: We report an exact map into one dimensional effective chains, of the\ntight-binding Hamiltonian for electrons in armchair and zigzag graphene\nnanoribbons with any uniaxial ripple. This mapping is used for studying the\neffect of uniaxial periodic ripples, taking into account the relative\norientation changes between $\\pi$ orbitals. Such effects are important for\nshort wavelength ripples, while for long-wave ones, the system behaves nearly\nas strained graphene. The spectrum has a complex nature, akin to the Hofstadter\nbutterfly with a rich localization behavior. Gaps at the Fermi level and\ndispersionless bands were observed, as well. The complex features of the\nspectrum arise as a consequence of the quasiperiodic or periodic nature of the\neffective one dimensional system. Some features of these systems are\nunderstandable by considering weakly coupled dimers. The eigenenergies of such\ndimers are highly degenerated and the net effect of the ripple can be seen as a\nperturbation potential that splits the energy spectrum. Several particular\ncases were analytically solved to understand such feature."
    },
    {
        "anchor": "Thermal Conductivity and Thermal Rectification in Graphene Nanoribbons:\n  a Molecular Dynamics Study: We have used molecular dynamics to calculate the thermal conductivity of\nsymmetric and asymmetric graphene nanoribbons (GNRs) of several nanometers in\nsize (up to ~4 nm wide and ~10 nm long). For symmetric nanoribbons, the\ncalculated thermal conductivity (e.g. ~2000 W/m-K @400K for a 1.5 nm {\\times}\n5.7 nm zigzag GNR) is on the similar order of magnitude of the experimentally\nmeasured value for graphene. We have investigated the effects of edge chirality\nand found that nanoribbons with zigzag edges have appreciably larger thermal\nconductivity than nanoribbons with armchair edges. For asymmetric nanoribbons,\nwe have found significant thermal rectification. Among various\ntriangularly-shaped GNRs we investigated, the GNR with armchair bottom edge and\na vertex angle of 30{\\deg} gives the maximal thermal rectification. We also\nstudied the effect of defects and found that vacancies and edge roughness in\nthe nanoribbons can significantly decrease the thermal conductivity. However,\nsubstantial thermal rectification is observed even in the presence of edge\nroughness.",
        "positive": "Topological Insulator Nanowires and Nanoribbons: Recent theoretical calculations and photoemission spectroscopy measurements\non the bulk Bi2Se3 material show that it is a three-dimensional topological\ninsulator possessing conductive surface states with nondegenerate spins,\nattractive for dissipationless electronics and spintronics applications.\nNanoscale topological insulator materials have a large surface-to-volume ratio\nthat can manifest the conductive surface states and are promising candidates\nfor devices. Here we report the synthesis and characterization of high quality\nsingle crystalline Bi2Se3 nanomaterials with a variety of morphologies. The\nsynthesis of Bi2Se3 nanowires and nanoribbons employs Au-catalyzed\nvapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces,\nare formed by stacking nanoplatelets along the axial direction of the wires.\nNanoribbons are grown along [11-20] direction with a rectangular cross-section\nand have diverse morphologies, including quasi-one-dimensional, sheetlike,\nzigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on\nnanoribbons show atomically smooth surfaces with ~ 1 nm step edges, indicating\nsingle Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb\natomic lattice, suggesting that the STM tip couples not only to the top Se\natomic layer, but also to the Bi atomic layer underneath, which opens up the\npossibility to investigate the contribution of different atomic orbitals to the\ntopological surface states. Transport measurements of a single nanoribbon\ndevice (four terminal resistance and Hall resistance) show great promise for\nnanoribbons as candidates to study topological surface states."
    },
    {
        "anchor": "Relaxation time and critical slowing down of a spin-torque oscillator: The relaxation phenomena of spin-torque oscillators consisting of\nnanostructured ferromagnets are interesting research targets in magnetism. A\ntheoretical study on the relaxation time of a spin-torque oscillator from one\nself-oscillation state to another is investigated. By solving the\nLandau-Lifshitz-Gilbert equation both analytically and numerically, it is shown\nthat the oscillator relaxes to the self-oscillation state exponentially within\na few nanoseconds, except when magnetization is close to a critical point. The\nrelaxation rate, which is an inverse of relaxation time, is proportional to the\ncurrent. On the other hand, a critical slowing down appears near the critical\npoint, where relaxation is inversely proportional to time, and the relaxation\ntime becomes on the order of hundreds of nanoseconds. These conclusions are\nprimarily obtained for a spin-torque oscillator consisting of a perpendicularly\nmagnetized free layer and an in-plane magnetized pinned layer, and are further\ndeveloped for application to arbitrary types of spin-torque oscillators.",
        "positive": "Hydrodynamic electron transport and nonlinear waves in graphene: We derive the system of hydrodynamic equations governing the collective\nmotion of massless fermions in graphene. The obtained equations demonstrate the\nlack of Galilean- and Lorentz invariance, and contain a variety of nonlinear\nterms due to quasi-relativistic nature of carriers. Using those equations, we\nshow the possibility of soliton formation in electron plasma of gated graphene.\nThe quasi-relativistic effects set an upper limit for soliton amplitude, which\nmarks graphene out of conventional semiconductors. The lack of Galilean and\nLorentz invariance of hydrodynamic equations is revealed in spectra of plasma\nwaves in the presence of steady flow, which no longer obey the relations of\nDoppler shift. The possibility of plasma wave excitation by direct current in\ngraphene channels is also discussed."
    },
    {
        "anchor": "Violation of the Wiedemann-Franz law in coupled thermal and power\n  transport of optical waveguide arrays: In isolated nonlinear optical waveguide arrays with bounded energy spectrum,\nsimultaneous conservation of energy and power of the optical modes enables\nstudy of coupled thermal and particle transport in the negative temperature\nregime. Here, based on exact numerical simulation and rationale from Landauer\nformalism, we predict generic violation of the Wiedemann-Franz law in such\nsystems. This is rooted in the spectral decoupling of thermal and power current\nof optical modes, and their different temperature dependence. Our work extends\nthe study of coupled thermal and particle transport into unprecedented regimes,\nnot reachable in natural condensed matter and atomic gas systems.",
        "positive": "Topological Superconductivity and Majorana Fermions in Metallic\n  Surface-States: Heavy metals, such as Au, Ag, and Pb, often have sharp surface states that\nare split by strong Rashba spin-orbit coupling. The strong spin-orbit coupling\nand two-dimensional nature of these surface states make them ideal platforms\nfor realizing topological superconductivity and Majorana fermions. In this\npaper, we further develop a proposal to realize Majorana fermions at the ends\nof quasi-one-dimensional metallic wires. We show how superconductivity can be\ninduced on the metallic surface states by a combination of proximity effect,\ndisorder, and interactions. Applying a magnetic field along the wire can drive\nthe wire into a topologically non-trivial state with Majorana end-states.\nUnlike the case of a perpendicular field, where the chemical potential must be\nfined tuned near the Rashba-band crossing, the parallel field allows one to\nrealize Majoranas for arbitrarily large chemical potential. We then show that,\ndespite the presence of a large carrier density from the bulk metal, it is\nstill possible to effectively control the chemical potential of the surface\nstates by gating. The simplest version of our proposal, which involves only an\nAu(111) film deposited on a conventional superconductor, should be readily\nrealizable."
    },
    {
        "anchor": "Nonlinear cavity feeding and unconventional photon statistics in\n  solid-state cavity QED revealed by many-level real-time path-integral\n  calculations: The generation of photons in a microcavity coupled to a laser-driven quantum\ndot interacting with longitudinal acoustic (LA) phonons is studied in the\nregime of simultaneously strong driving and strong dot-cavity coupling. The\nstationary cavity photon number is found to depend in a non-trivial way on the\ndetuning between the laser and the exciton transition in the dot. In\nparticular, the maximal efficiency of the cavity feeding is obtained for\ndetunings corresponding to transition energies between cavity-dressed states\nwith excitation numbers larger than one. Phonons significantly enhance the\ncavity feeding at large detunings. In the strong-driving, strong-coupling\nlimit, the photon statistics is highly non-Poissonian. While without phonons a\ndouble-peaked structure in the photon distribution is predicted, phonons make\nthe photon statistics thermal-like with very high effective temperatures $\\sim\n10^5$ K, even for low phonon temperatures $\\sim 4$ K. These results were\nobtained by numerical calculations where the driving, the dot-cavity coupling\nand the dot-phonon interactions are taken into account without approximations.\nThis is achieved by a reformulation of an exact iterative path-integral scheme\nwhich is applicable for a large class of quantum-dissipative systems and which\nin our case reduces the numerical demands by 15 orders of magnitude.",
        "positive": "Hierarchical Quantum Master Equation Approach to Electronic-Vibrational\n  Coupling in Nonequilibrium Transport through Nanosystems: Within the hierarchical quantum master equation (HQME) framework, an approach\nis presented, which allows a numerically exact description of nonequilibrium\ncharge transport in nanosystems with strong electronic-vibrational coupling.\nThe method is applied to a generic model of vibrationally coupled transport\nconsidering a broad spectrum of parameters ranging from the nonadiabatic to the\nadiabatic regime and including both resonant and off-resonant transport. We\nshow that nonequilibrium effects are important in all these regimes. In\nparticular in the off-resonant transport regime, the inelastic co-tunneling\nsignal is analyzed for a vibrational mode in full nonequilibrium, revealing a\ncomplex interplay of different transport processes and deviations from the\ncommonly used $G_0/2$-thumb-rule. In addition, the HQME-approach is used to\nbenchmark approximate master equation and nonequilibrium Green's function\nmethods."
    },
    {
        "anchor": "Nonlinear electric transport in graphene with magnetic disorder: The influence of magnetic impurities on the transport properties of graphene\nis investigated in the regime of strong applied electric fields. As a result of\nelectron-hole pair creation, the response becomes nonlinear and dependent on\nthe magnetic polarization. In the paramagnetic phase, time reversal symmetry is\nstatistically preserved, and transport properties are similar to the clean\ncase. At variance, in the antiferromagnetic phase, the system undergoes a\ntransition between a superdiffusive to a subdiffusive spreading of a wave\npacket, signaling the development of localized states. This critical regime is\ncharacterized by the appearance of electronic states with a multifractal\ngeometry near the gap. The local density of states concentrates in large\npatches having a definite charge-spin correlation. In this state, the\nconductivity tends to half the minimum conductivity of clean graphene.",
        "positive": "Ultralow 1/f Noise in a Heterostructure of Superconducting Epitaxial\n  Cobalt-Disilicide Thin Film on Silicon: High-precision resistance noise measurements indicate that the epitaxial\nCoSi$_2$/Si hetero-structures at 150 K and 2 K (slightly above its\nsuperconducting transition temperature $T_c$ of 1.54 K) exhibit an unusually\nlow 1/f noise level in the frequency range of 0.008-0.2 Hz. This corresponds to\nan upper limit of Hooge constant $\\gamma \\leq 3 \\times 10^{-6}$, about 100\ntimes lower than that of single-crystalline aluminum films on SiO$_2$ capped Si\nsubstrates. Supported by high-resolution cross-sectional transmission electron\nmicroscopy studies, our analysis reveals that the 1/f noise is dominated by\nexcess interfacial Si atoms and their dimer reconstruction induced fluctuators.\nUnbonded orbitals (i.e., dangling bonds) on excess Si atoms are intrinsically\nrare at the epitaxial CoSi$_2$/Si(100) interface, giving limited\ntrapping-detrapping centers for localized charges. With its excellent\nnormal-state properties, CoSi$_2$ has been used in silicon-based integrated\ncircuits for decades. The intrinsically low noise properties discovered in this\nwork could be utilized for developing quiet qubits and scalable superconducting\ncircuits for future quantum computing."
    },
    {
        "anchor": "Modulated longitudinal gates on encoded spin-qubits via curvature\n  couplings to a superconducting cavity: We propose entangling operations based on the energy curvature couplings of\nencoded spin qubits to a superconducting cavity, exploring the non-linear qubit\nresponse to a gate voltage variation. For a two-qubit ($n$-qubit) entangling\ngate we explore acquired geometric phases via a time-modulated longitudinal\n$\\sigma_z$-coupling, offering gate times of 10s of ns even when the qubits and\nthe cavity are far detuned. No dipole moment is necessary: the qubit transverse\n$\\sigma_x$-coupling to the resonator is zero at the full sweet spot of the\nencoded spin qubit of interest (a triple quantum dot three-electron\nexchange-only qubit or a double quantum dot singlet-triplet qubit). This\napproach allows always-on, exchange-only qubits, for example, to stay on their\n\"sweet spots\" during gate operations, minimizing the charge noise and\neliminating an always-on static longitudinal qubit-qubit coupling. We calculate\nthe main gate errors due to the (1) diffusion (Johnson) noise and (2) damping\nof the resonator, the (3) $1/f$-charge noise qubit gate dephasing and\n$1/f$-noise on the longitudinal coupling, (4) qubit dephasing and ac-Stark\nfrequency shifts via photon fluctuations in the resonator, and (5)\nspin-dependent resonator frequency shifts (via a \"dispersive-like\" static\ncurvature coupling), most of them associated with the non-zero qubit energy\ncurvature (quantum capacitance). Using spin-echo-like error suppression at\noptimal regimes, gate infidelities of $10^{-2}-10^{-3}$ can be achieved with\nexperimentally existing parameters. The proposed schemes seem suitable for\nremote spin-to-spin entanglement of two spin-qubits or a cluster of\nspin-qubits: an important resource of quantum computing.",
        "positive": "Spin-wave excitation and propagation in microstructured waveguides of\n  yttrium iron garnet (YIG)/Pt bilayers: We present an experimental study of spin-wave excitation and propagation in\nmicrostructured waveguides patterned from a 100 nm thick yttrium iron garnet\n(YIG)/platinum (Pt) bilayer. The life time of the spin waves is found to be\nmore than an order of magnitude higher than in comparably sized metallic\nstructures despite the fact that the Pt capping enhances the Gilbert damping.\nUtilizing microfocus Brillouin light scattering spectroscopy, we reveal the\nspin-wave mode structure for different excitation frequencies. An exponential\nspin-wave amplitude decay length of 31 {\\mu}m is observed which is a\nsignificant step towards low damping, insulator based micro-magnonics."
    },
    {
        "anchor": "Observation of anomalous spin-torque generated by a ferromagnet: In this work we report observation of in-plane current induced out-of-plane\nmagnetic field driven torque in spin valve structure. Since ferromagnet has\nhigh spin orbit coupling it is expected to be the source of spin-orbit-torque\nas it possesses anomalous-Hall-effect (AHE: equivalent to spin Hall effect in\nheavy metal). So we have carried out spin-torque ferromagnetic resonance\n(ST-FMR) experiment in a spin valve (consists of a fixed magnet and a free\nmagnet which are separated by Cu spacer), passing in-plane radio frequency\ncurrent and measuring DC voltage. Our experimental results eventually indicate\nthat spin torque exerted on the free magnet is not caused due to the spin\ncurrent injection by the fixed magnet owing to its AHE, but it is originated\nfrom in-plane current driven out-of plane effective magnetic field. This is new\nclass of spin torque which is completely different from Slonczewski-spin\ntransfer torque and Rashba like field like torque. The effective out-of plane\nmagnetic field depends on the direction of current (in-plane) and magnetization\n(in-plane) of the pinned layer. One possible mechanism behind this\nunconventional torque could be intefacial spin-scattering which is also origin\nof current in-plane GMR effect. Most importantly this effective out-of plane\ntorque can be useful to switch out-of plane magnetic bits in spintronic memory\napplication.",
        "positive": "Diagrammatic description of a system coupled strongly to a bosonic bath: We study a system-bath description in the strong coupling regime where it is\nnot possible to derive a master equation for the reduced density matrix by a\ndirect expansion in the system-bath coupling. A particular example is a bath\nwith significant spectral weight at low frequencies. Through a unitary\ntransformation it can be possible to find a more suitable small expansion\nparameter. Within such approach we construct a formally exact expansion of the\nmaster equation on the Keldysh contour. We consider a system diagonally coupled\nto a bosonic bath and expansion in terms of a non-diagonal hopping term. The\nlowest-order expansion is equivalent to the so-called $P(E)$-theory or\nnon-interacting blip approximation (NIBA). The analysis of the higher-order\ncontributions shows that there are two different classes of higher-order\ndiagrams. We study how the convergence of this expansion depends on the form of\nthe spectral function with significant weight at zero frequency."
    },
    {
        "anchor": "Noise studies of magnetization dynamics in dilute magnetic semiconductor\n  heterostructures: We study theoretically and experimentally the frequency and temperature\ndependence of resistivity noise in semiconductor heterostructures delta-doped\nby Mn. The resistivity noise is observed to be non-monotonous as a function of\nfrequency. As a function of temperature, the noise increases by two orders of\nmagnitude for a resistivity increase of about 50%. We study two possible\nsources of resistivity noise -- dynamic spin fluctuations and charge\nfluctuations, and find that dynamic spin fluctuations are more relevant for the\nobserved noise data. The frequency and temperature dependence of resistivity\nnoise provide important information on the nature of the magnetic interactions.\nIn particular, we show how noise measurements can help resolve a long standing\ndebate on whether the Mn-doped GaAs is an p-d Zener/RKKY or double exchange\nferromagnet. Our analysis includes the effect of different kinds of disorder\nsuch as spin-glass type of interactions and a site-dilution type of disorder.\nWe find that the resistivity noise in these structures is well described by a\ndisordered RKKY ferromagnet model dynamics with a conserved order parameter.",
        "positive": "Terphenylthiazole-based self-assembled monolayers on cobalt with high\n  conductance photo-switching ratio for spintronics: Two new photo-switchable terphenylthiazoles molecules are synthesized and\nself-assembled as monolayers on Au and on ferromagnetic Co electrodes. The\nelectron transport properties probed by conductive atomic force microscopy in\nultra-high vacuum reveal a conductance of the light-induced closed (c) form\nlarger than for the open (o) form. We report an unprecedented conductance ratio\nup to 380 between the closed and open forms on Co for the molecule with the\nanchoring group (thiol) on the side of the two N atoms of the thiazole unit.\nThis result is rationalized by Density Functional Theory (DFT) calculations\ncoupled to the Non-Equilibrium Green's function (NEGF) formalism. These\ncalculations show that the high conductance in the closed form is due to a\nstrong electronic coupling between the terphenylthiazole molecules and the Co\nelectrode that manifests by a resonant transmission peak at the Fermi energy of\nthe Co electrode with a large broadening. This behavior is not observed for the\nsame molecules self-assembled on gold electrodes. These high conductance ratios\nmake these Co-based molecular junctions attractive candidates to develop and\nstudy switchable molecular spintronic devices."
    },
    {
        "anchor": "A driven fractal network: Possible route to efficient thermoelectric\n  application: An essential attribute of many fractal structures is self-similarity. A\nSierpinski gasket (SPG) triangle is a promising example of a fractal lattice\nthat exhibits localized energy eigenstates. In the present work, for the first\ntime we establish that a mixture of both extended and localized energy\neigenstates can be generated yeilding mobility edges at multiple energies in\npresence of a time-periodic driving field. We obtain several compelling\nfeatures by studying the transmission and energy eigenvalue spectra. As a\npossible application of our new findings, different thermoelectric properties\nare discussed, such as electrical conductance, thermopower, thermal conductance\ndue to electrons and phonons. We show that our proposed method indeed exhibits\nhighly favorable thermoelectric performance. The time-periodic driving field is\nassumed through an arbitrarily polarized light, and its effect is incorporated\nvia Floquet-Bloch ansatz. All transport phenomena are worked out using Green's\nfunction formalism following the Landauer-B\\\"{u}ttiker prescription.",
        "positive": "Conductance oscillations in Chern insulator junctions: valley-isospin\n  dependence and Aharonov-Bohm effects: The transport properties of Chern insulator junctions generated by bipolar\njunctions in quantum Hall graphene are theoretically studied in the coherent\nregime. Coherent transport across the junction exhibits two mesoscopic\nfeatures: valley-isospin dependence of the quantum Hall conductance, and the\nAharonov-Bohm (AB) effects with the interface channels. We demonstrate that the\nvalley-isospin dependence can be measured in a graphene sample with perfect\nedge terminations, resulting in conductance oscillation for the smallest Chern\nnumber case. On the other hand, while conductance plateaus are found to be\nunclear for larger Chern numbers, the conductance exhibits an oscillatory\nbehavior of which period is relatively longer than the valley-isospin dependent\noscillation. This conductance oscillation is ascribed to the AB effect, which\nis implicitly created by the split metallic channels near the junction\ninterface. We point out that a possible origin of the unclear plateaus\npreviously speculated to be incompleteness in realistic devices is the\nlow-visibility conductance oscillation due to unequal beam splitting."
    },
    {
        "anchor": "Improved Performance of Tunneling FET Based on Hetero Graphene\n  Nanoribbons: A heterojunction tunneling field effect transistor based on armchair graphene\nnanoribbons is proposed and studied using ballistic quantum transport\nsimulation based on 3D real space nonequilibrium Green's function formalism. By\nusing low band gap nanoribbons as the source/drain material, the hetero-\nstructure shows better performance including higher on current, lower off\ncurrent, and improved steep subthreshold swings compared with homostructure. It\nis also found the device performance greatly depends on the source/drain\ndopping density. High doping density leads to fewer density states in the\nsource and degrades the device performance.",
        "positive": "Spin relaxation of \"upstream\" electrons in quantum wires: Failure of the\n  drift diffusion model: The classical drift diffusion (DD) model of spin transport treats spin\nrelaxation via an empirical parameter known as the ``spin diffusion length''.\nAccording to this model, the ensemble averaged spin of electrons drifting and\ndiffusing in a solid decays exponentially with distance due to spin dephasing\ninteractions. The characteristic length scale associated with this decay is the\nspin diffusion length. The DD model also predicts that this length is different\nfor ``upstream'' electrons traveling in a decelerating electric field than for\n``downstream'' electrons traveling in an accelerating field. However this\npicture ignores energy quantization in confined systems (e.g. quantum wires)\nand therefore fails to capture the non-trivial influence of subband structure\non spin relaxation. Here we highlight this influence by simulating upstream\nspin transport in a multi-subband quantum wire, in the presence of\nD'yakonov-Perel' spin relaxation, using a semi-classical model that accounts\nfor the subband structure rigorously.\n  We find that upstream spin transport has a complex dynamics that defies the\nsimplistic definition of a ``spin diffusion length''.\n  In fact, spin does not decay exponentially or even monotonically with\ndistance, and the drift diffusion picture fails to explain the qualitative\nbehavior, let alone predict quantitative features accurately. Unrelated to spin\ntransport, we also find that upstream electrons undergo a ``population\ninversion'' as a consequence of the energy dependence of the density of states\nin a quasi one-dimensional structure."
    },
    {
        "anchor": "Self-assembled Pt nanowires on Ge(001): Relaxation effects: Absorption of Pt on the Ge(001) surface results in stable self-organized Pt\nnanowires, extending over some hundred nanometers. Based on band structure\ncalculations within density functional theory and the generalized gradient\napproximation, the structural relaxation of the Ge--Pt surface is investigated.\nThe surface reconstruction pattern obtained agrees well with findings from\nscanning tunneling microscopy. In particular, strong Pt--Pt dimerization is\ncharacteristical for the nanowires. The surface electronic structure is\nsignificantly perturbed due to Ge--Pt interaction, which induces remarkable\nshifts of Ge states towards the Fermi energy. As a consequence, the topmost Ge\nlayers are subject to a metal-insulator transition.",
        "positive": "Bound states in the continuum poisoned by Majorana fermions: In this work, we study the bound states in the continuum (BICs) in a system\nformed by a triple quantum dot array embedded between two one-dimensional\ntopological superconductors, both hosting Majorana bound states (MBSs) at its\nends. The results show the formation of BICs with topological characteristics\ndue to the presence of MBSs. The latter is a consequence of the interplay\nbetween the BIC arising from quantum dots states by means of energy level\nsymmetry breaking through gate voltages, and MBSs leaked into the quantum dots.\nThe BIC is not observed when both TSCs are in long wire limit, i. e. for\nvanishing inter MBSs coupling, while it projects into the electronic\ntransmission whenever the inter MBSs couplings are away from zero, regardless\nif they are different and/or the phase difference between both TSCs. We study\nthe behavior of BICs poisoned by MBSs as a function of the parameters that are\ncontrolling the system. We believe our findings could be useful to implement a\nprotection tool for BICs using MBSs based on tunable gate voltages."
    },
    {
        "anchor": "Optical properties of graphane in infrared range: The theory of optical effects in hydrogenated graphene (graphane) in\nterahertz and infrared range is developed, including the analysis of complex\nconductivity, reflection coefficient for graphane on a substrate and dispersion\nof surface plasmon-polaritons. The calculations are based on quite simple\nanalytical approximation of graphane band structure in the vicinity of\nGamma-point and on the modified model of quantum coherence relaxation.\nComparison of the obtained theoretical results with corresponding experimental\ndata can be used both for the determination of graphane characteristics (Fermi\nlevel, relaxation rate etc.) and for the investigation of potential\napplications of this material in the design of new optical elements.",
        "positive": "The role of contact resistance in graphene field-effect devices: The extremely high carrier mobility and the unique band structure, make\ngraphene very useful for field-effect transistor applications. According to\nseveral works, the primary limitation to graphene based transistor performance\nis not related to the material quality, but to extrinsic factors that affect\nthe electronic transport properties. One of the most important parasitic\nelement is the contact resistance appearing between graphene and the metal\nelectrodes functioning as the source and the drain. Ohmic contacts to graphene,\nwith low contact resistances, are necessary for injection and extraction of\nmajority charge carriers to prevent transistor parameter fluctuations caused by\nvariations of the contact resistance. The International Technology Roadmap for\nSemiconductors, toward integration and down-scaling of graphene electronic\ndevices, identifies as a challenge the development of a CMOS compatible process\nthat enables reproducible formation of low contact resistance. However, the\ncontact resistance is still not well understood despite it is a crucial barrier\ntowards further improvements. In this paper, we review the experimental and\ntheoretical activity that in the last decade has been focusing on the reduction\nof the contact resistance in graphene transistors. We will summarize the\nspecific properties of graphene-metal contacts with particular attention to the\nnature of metals, impact of fabrication process, Fermi level pinning, interface\nmodifications induced through surface processes, charge transport mechanism,\nand edge contact formation."
    },
    {
        "anchor": "Programmable Nanowrinkle-Induced Room-Temperature Exciton Localization\n  in Monolayer WSe2: Localized states in two-dimensional (2D) transition metal dichalcogenides\n(TMDCs) have been the subject of intense study, driven by potential\napplications in quantum information science. Despite the rapidly growing\nknowledge surrounding these emitters, their microscopic nature is still not\nfully understood, limiting their production and application. Motivated by this\nchallenge, and by recent theoretical and experimental evidence showing that\nnanowrinkles generate localized room-temperature emitters, we demonstrate a\nmethod to intentionally induce wrinkles with collections of stressors, showing\nthat long-range wrinkle direction and position are controllable with patterned\narray design. Nano-photoluminescence (nano-PL) imaging combined with detailed\nstrain modeling based on measured wrinkle topography establishes a correlation\nbetween wrinkle properties, particularly shear strain, and localized exciton\nemission. Beyond the array-induced super-wrinkles, nano-PL spatial maps further\nreveal that the strain environment around individual stressors is heterogeneous\ndue to the presence of fine wrinkles that are less deterministic. Detailed\nnanoscale hyperspectral images uncover a wide range of low-energy emission\npeaks originating from these fine wrinkles, and show that the states can be\ntightly confined to regions < 10 nm, even in ambient conditions. These results\nestablish a promising potential route towards realizing room temperature\nquantum emission in 2D TMDC systems.",
        "positive": "Single-shot readout of an electron spin in silicon: The size of silicon transistors used in microelectronic devices is shrinking\nto the level where quantum effects become important. While this presents a\nsignificant challenge for the further scaling of microprocessors, it provides\nthe potential for radical innovations in the form of spin-based quantum\ncomputers and spintronic devices. An electron spin in Si can represent a\nwell-isolated quantum bit with long coherence times because of the weak\nspin-orbit coupling and the possibility to eliminate nuclear spins from the\nbulk crystal. However, the control of single electrons in Si has proved\nchallenging, and has so far hindered the observation and manipulation of a\nsingle spin. Here we report the first demonstration of single-shot,\ntime-resolved readout of an electron spin in Si. This has been performed in a\ndevice consisting of implanted phosphorus donors coupled to a\nmetal-oxide-semiconductor single-electron transistor - compatible with current\nmicroelectronic technology. We observed a spin lifetime approaching 1 second at\nmagnetic fields below 2 T, and achieved spin readout fidelity better than 90%.\nHigh-fidelity single-shot spin readout in Si opens the path to the development\nof a new generation of quantum computing and spintronic devices, built using\nthe most important material in the semiconductor industry."
    },
    {
        "anchor": "Giant proximity exchange and valley splitting in transition metal\n  dichalcogenide/$h\\mathrm{BN}$/(Co, Ni) heterostructures: We investigate the proximity-induced exchange coupling in transition-metal\ndichalcogenides (TMDCs), originating from spin injector geometries composed of\nhexagonal boron-nitride (hBN) and ferromagnetic (FM) cobalt (Co) or nickel\n(Ni), from first-principles. We employ a minimal tight-binding Hamiltonian that\ncaptures the low energy bands of the TMDCs around K and K' valleys, to extract\norbital, spin-orbit, and exchange parameters. The TMDC/hBN/FM heterostructure\ncalculations show that due to the hBN buffer layer, the band structure of the\nTMDC is preserved, with an additional proximity-induced exchange splitting in\nthe bands. We extract proximity exchange parameters in the 1--10 meV range,\ndepending on the FM. The combination of proximity-induced exchange and\nintrinsic spin-orbit coupling (SOC) of the TMDCs, leads to a valley\npolarization, translating into magnetic exchange fields of tens of Tesla. The\nextracted parameters are useful for subsequent exciton calculations of TMDCs in\nthe presence of a hBN/FM spin injector. Our calculated absorption spectra show\nlarge splittings for the exciton peaks; in the case of MoS$_2$/hBN/Co we find a\nvalue of about 8 meV, corresponding to about 50 Tesla external magnetic field\nin bare TMDCs. The reason lies in the band structure, where a hybridization\nwith Co $d$ orbitals causes a giant valence band exchange splitting of more\nthan 10 meV. Structures with Ni do not show any $d$ level hybridization\nfeatures, but still sizeable proximity exchange and exciton peak splittings of\naround 2 meV are present in the TMDCs.",
        "positive": "Transport and localization of indirect excitons in a van der Waals\n  heterostructure: Long lifetimes of spatially indirect excitons (IXs), also known as interlayer\nexcitons, allow implementing both quantum exciton systems and long-range\nexciton transport. Van der Waals heterostructures (HS) composed of atomically\nthin layers of transition-metal dichalcogenides (TMD) offer the opportunity to\nexplore IXs in moir\\'e superlattices. The moir\\'e IXs in TMD HS form the\nmaterials platform for exploring the Bose-Hubbard physics and superfluid and\ninsulating phases in periodic potentials. IX transport in TMD HS was\nintensively studied and diffusive IX transport with $1/e$ decay distances\n$d_{1/e}$ up to $\\sim 3$ $\\mu$m was realized. In this work, we present in\nMoSe$_2$/WSe$_2$ HS the IX long-range transport with $d_{1/e}$ exceeding 100\n$\\mu$m and diverging at the optical excitation resonant to spatially direct\nexcitons. The IX long-range transport vanishes at high temperatures. With\nincreasing IX density, IX localization, then IX long-range transport, and then\nIX reentrant localization is observed. The results are in qualitative agreement\nwith the Bose-Hubbard theory of bosons in periodic potentials predicting\nsuperfluid at $N \\sim 1/2$ and insulating at $N \\sim 0$ and $N \\sim 1$ phases\nfor the number of bosons per site of the periodic potential $N$."
    },
    {
        "anchor": "Growth, Electronic Structure and Superconductivity of Ultrathin\n  Epitaxial CoSi2 Films: We report growth, electronic structure and superconductivity of ultrathin\nepitaxial CoSi2 films on Si(111). At low coverages, preferred islands with 2, 5\nand 6 monolayers height develop, which agrees well with the surface energy\ncalculation. We observe clear quantum well states as a result of electronic\nconfinement and their dispersion agrees well with density functional theory\ncalculations, indicating weak correlation effect despite strong contributions\nfrom Co 3d electrons. Ex-situ transport measurements show that\nsuperconductivity persists down to at least 10 monolayers, with reduced Tc but\nlargely enhanced upper critical field. Our study opens up the opportunity to\nstudy the interplay between quantum confinement, interfacial symmetry breaking\nand superconductivity in an epitaxial silicide film, which is technologically\nrelevant in microelectronics.",
        "positive": "Three-Terminal Energy Harvester with Coupled Quantum Dots: Rectification of thermal fluctuations in mesoscopic conductors is the key\nidea of today's attempts to build nanoscale thermoelectric energy harvesters in\norder to convert heat into a useful electric power. So far, most concepts make\nuse of the Seebeck effect in a two-terminal geometry where heat and charge are\nboth carried by the same particles. Here, we experimentally demonstrate the\nworking principle of a new kind of energy harvester, proposed recently using\ntwo capacitively coupled quantum dots. We show that due to its novel\nthree-terminal design which spatially separates the heat reservoir from the\nconductor circuit, the directions of charge and heat flow become decoupled in\nour device. This enables us to manipulate the direction of the generated charge\ncurrent by means of external gate voltages while leaving the direction of heat\nflow unaffected. Our results pave the way for a new generation of\nmulti-terminal, highly efficient nanoscale heat engines."
    },
    {
        "anchor": "Electron - hole asymmetry and activation energy in quantum Hall\n  ferromagnets: We argue that the dissipative transport in ferromagnetic quantum Hall effect\nliquids at $\\nu=2N+1$ is dominated by the thermal activation of pairs\nconsisting of an electron and an antiskyrmion (topological texture which\nrepresents a hole with 'screened' exchange interaction), thus manifesting the\nlack of electron-hole symmetry in quantum Hall ferromagnets. We find that the\nactivation energy of such a pair is not the exchange energy, but is determined\nby the interplay between the excess Zeeman energy of a skyrmion and the\ncharging energy of its topological texture: $${\\cal E}=a\\epsilon_{{\\rm\nZ}}^{1/3}E_{{\\rm C}}^{2/3}\\ln ^{1/3}(\\frac{\\Im_{i}}{E_{{\\rm\nC}}^{2/3}\\epsilon_{{\\rm Z}}^{1/3}}), E_{{\\rm C}}=\\frac{e^{2}}{\\chi \\lambda}, $$\nwith $ a\\approx 1.75$.",
        "positive": "Parametric mechanism of magnetization reversal in FeCoB nanomagnet by a\n  magnetic field of spin-accumulated electrons: Spin-polarized electrons are accumulated at nanomagnet boundaries due to the\nSpin Hall effect. The small magnetic field, which is induced by the spin\naccumulation, is able to reverse the nanomagnet magnetization when the\nconditions of parametric resonance are met. The features of this parametric\nmechanism of magnetization reversal are studied experimentally and\ntheoretically. It is shown that the efficient parametric magnetization reversal\nis possible for both cases when the electron current is modulated at the Larmor\nfrequency and when the current is not modulated at all."
    },
    {
        "anchor": "Theory of light-induced current in molecular-tunneling junctions excited\n  with intense shaped pulses: A theory for light-induced current by strong optical pulses in\nmolecular-tunneling junctions is described. We consider a molecular bridge\nrepresented by its highest occupied and lowest unoccupied levels, HOMO and\nLUMO, respectively. We take into account two types of couplings between the\nmolecule and the metal leads: electron transfer that gives rise to net current\nin the biased junction and energy transfer between the molecule and\nelectron-hole excitations in the leads. Using a Markovian approximation, we\nderive a closed system of equations for the expectation values of the relevant\nvariables: populations and molecular polarization that are binary, and exciton\npopulations that are tetradic in the annihilation and creation operators for\nelectrons in the molecular states. We have proposed an optical control method\nusing chirped pulses for enhancing charge transfer in unbiased junctions where\nthe bridging molecule is characterized by a strong charge-transfer transition.\nAn approximate analytical solution of the resulting dynamical equation is\nsupported by a full numerical solution. When energy transfer between the\nmolecule and electron-hole excitations in the leads is absent, the optical\ncontrol problem for inducing charge transfer with linearly chirped pulse can be\nreduced to the Landau-Zener transition to a decaying level. When chirp is fast\nwith respect to the rate of the electron transfer, the Landau theory is\nrecovered. The proposed control mechanism is potentially useful for developing\nnovel opto-electronic single-electron devices with optical gating based on\nmolecular nanojunctions.",
        "positive": "Multilayer graphene under vertical electric field: We study the effect of vertical electric field (E-field) on the electronic\nproperties of multilayer graphene. We show that the effective mass, electron\nvelocity and density-of-state of a bilayer graphene are modified under the\nE-field. We also study the transformation of the band structure of multilayer\ngraphenes. E-field induces finite (zero) bandgap in the even (odd)-layer\nABA-stacking graphene. On the other hand, finite bandgap is induced in all\nABC-stacking graphene. We also identify the optimum E-field to obtain the\nmaximum bandgap in the multilayer graphenes. Finally we compare our results\nwith the experimental results of a field-effect-transistor."
    },
    {
        "anchor": "Berry-phase switch in electrostatically-confined topological surface\n  states: Here we visualize the trapping of topological surface states in the circular\nn-p junctions on the top surface of the 7-quintuple-layer three dimensional\n(3D) topological insulator (TI) Sb2Te3 epitaxial films. As shown by spatially-\nand field-dependent tunneling spectra, these trapped resonances show\nfield-induced splittings between the degenerate time-reversal-symmetric states\nat zero magnetic field. These behaviors are attributed unambiguously to\nBerry-phase switch by comparing the experimental data with both numerical and\nsemi-classical simulations. The successful electrostatic trapping of\ntopological surface states in epitaxial films and the observation of\nBerry-phase switch provide a rich platform of exploiting new ideas for TI-based\nquantum devices.",
        "positive": "Nonequilibrium Magnetization of a Two-Dimensional Electron Gas in a\n  Static Magnetic Field: Using a sensitive DC torque magnetometer we measure the orbital magnetization\nby sweeping the density at fixed magnetic fields on GaAs-AlGaAs\nheterostructures. At low temperatures strong nonequilibrium magnetization\nsignals dominate the data. In literature the observation of nonequilibrium\nsignals are often associated with eddy currents generated by sweeping the\nmagnetic field. The elimination of a changing magnetic field then poses a\nquestion regarding the origin of these signals. Our data suggests another\nsource of nonequilibrium magnetization potentially due to the change of area\noccupied by compressible and incompressible states as one sweeps the Fermi\nenergy from one Landau level to the next."
    },
    {
        "anchor": "Emergent topological mirror insulator in t2g-orbital systems: The electronic band structure of iron pnictides exhibits four Dirac cones,\nwhich are due to crystal symmetry and orbital bonding orientation. This\nhallmark signature presents the pnictide family as an ideal candidate in the\nsearch for quasi-two-dimensional topological crystalline insulators. In this\nreport, we explore interaction-induced topological phases which cannot be\ndescribed by conventional local order parameters. Based on a model Hamiltonian\nour symmetry analysis shows that sponta- neous novel topological phases may be\nrealized in compounds with tetragonal crystal field symmetry, where the\nelectrons occupy the two degenerate t2g energy levels at low temperature. We\nidentify two stable topological phases in the ground state, which emerge from\nspontaneous orbital current order. These currents are driven by electronic\ncorrelations caused by inter-orbital Coulomb interactions. The first\ntopological phase is an anomalous orbital Hall phase, characterized by a\nnonzero Chern number, while the second topological phase has a vanishing Chern\nnumber, though with an extra Z2-like invariant that preserves parity. More\nspecifically, the interaction-induced novel phase of the quasi-two-dimensional\ntopological crystalline insulator is protected by mirror reflection symmetries\nand therefore may be realized in pnictides.",
        "positive": "Energy conversion in thermoelectric materials of SnSSe and SnS$_2$: a\n  Monte-Carlo simulation of Boltzmann transport equation: In the present work, thermal transport and energy conversation in two\nthermoelectrically efficient candidates of Janus SnSSe and SnS$_2$ are\ninvestigated within the non-equilibrium Monte Carlo simulation of phonon\nBoltzmann equation. The phonon analysis is performed to determine the\ncontributed phonons in heat transport. The results present that the dominant\nparticipating phonons are longitudinal acoustic ones while the least belongs to\nthe transverse acoustic (TA) mode. Both materials reached the very high maximum\ntemperature in response to the implied wasted heat. This is attributed to the\nlow presence of the critical TA phonons. Also, the temperature profile achieved\nduring the heating and cooling of the materials is studied. It is obtained that\nthe heat propagation through the SnS$_2$ is, at first, swifter, which results\nin a temperature gradient through the whole material which is less than that of\nthe SnSSe. As the time passes, the heat transfer that is directly related to\nthe material thermal conductivity, slows down. So, the behavior of the SnS$_2$\nand SnSSe, in case of the heat propagation status, becomes similar. More, the\nbehavior of the thermoelectric figure of merit (zT), the efficiency ($\\eta$),\nand the generated voltage have been figured out. It is stated that the higher\nzT and $\\eta$ do not guarantee a larger generated Seebeck voltage. This is\ntrue, while the generated Seebeck voltage is related to the temperature\ndifference between the heated and the cold junction. Accordingly, how far the\ntemperature of matter rises in response to the implied wasted heat is related\nto the obtained voltage. Mainly, it is presented that the maximum temperature\nthat a material achieves, alongside the temperature gradient and material\nproperty Seebeck coefficient, are essential in introducing thermoelectrically\nefficient materials with reasonable thermal to electrical energy conversion."
    },
    {
        "anchor": "Majorana meets Coxeter: Non-Abelian Majorana Fermions and Non-Abelian\n  Statistics: We discuss statistics of vortices having zero-energy non-Abelian Majorana\nfermions inside them. Considering the system of multiple non-Abelian vortices,\nwe derive a non-Abelian statistics that differs from the previously derived\nnon-Abelian statistics. The new non-Abelian statistics presented here is given\nby a tensor product of two different groups, namely the non-Abelian statistics\nobeyed by the Abelian Majorana fermions and the Coxeter group. The Coxeter\ngroup is a symmetric group related to the symmetry of polytopes in a\nhigh-dimensional space. As the simplest example, we consider the case in which\na vortex contains three Majorana fermions that are mixed with each other under\nthe SO(3) transformations. We concretely present the representation of the\nCoxeter group in our case and its geometrical expressions in the\nhigh-dimensional Hilbert space constructed from non-Abelian Majorana fermions.",
        "positive": "Proximity effect in planar TiN-Silicon junctions: We measured the low temperature subgap resistance of titanium nitride\n(superconductor, Tc=4.6K)/highly doped silicon (degenerated semiconductor) SIN\njunctions, where I stands for the Schottky barrier. At low energies, the subgap\nconductance is enhanced due to coherent backscattering of the electrons towards\nthe interface by disorder in the silicon (''reflectionless tunneling''). This\nZero Bias Anomaly (ZBA) is destroyed by the temperature or the magnetic field\nabove 250mK or 0.04T respectively. The overall differential resistance behavior\n(vs temperature and voltage) is compared to existing theories and values for\nthe depairing rate and the barrier transmittance are extracted. Such an\nanalysis leads us to introduce an effective temperature for the electrons and\nto discuss heat dissipation through the SIN interface."
    },
    {
        "anchor": "Dynamical Instabilities and Deterministic Chaos in Ballistic Electron\n  Motion in Semiconductor Superlattices: We consider the motion of ballistic electrons within a superlattice miniband\nunder the influence of an alternating electric field. We show that the\ninteraction of electrons with the self-consistent electromagnetic field\ngenerated by the electron current may lead to the transition from regular to\nchaotic dynamics. We estimate the conditions for the experimental observation\nof this deterministic chaos and discuss the similarities of the superlattice\nsystem with the other condensed matter and quantum optical systems.",
        "positive": "PH-Pfaffian order in a translationally and rotationally invariant system: The PH-Pfaffian topological order has been proposed as a candidate order for\nthe $\\nu=5/2$ quantum Hall effect. The PH-Pfaffian liquid is known to be the\nground state in several coupled wire and coupled stripe constructions. No\ntranslationally and rotationally invariant models with the PH-Pfaffian ground\nstate have been identified so far. By employing anyon condensation on top of a\ntopological order, allowed in an isotropic system, we argue that the\nPH-Pfaffian order is possible in the presence of rotational and translational\nsymmetries."
    },
    {
        "anchor": "Role of short-range order in manipulating light absorption in disordered\n  media: Structural correlations have a significant effect on light propagation in\ndisordered media. We numerically investigate the role of short-range order in\nlight absorption in thin films with disordered nanoholes. Two types of\ndisordered distributions, including stealthy hyperuniform (SHU) and hard disk\n(HD) patterns with different degrees of short-range order, are studied. We find\nthat Bragg scattering induced by short-range order results in the appearance of\na gradually sharper absorption peak with the increasing of degrees of\nshort-range order ($\\chi$, $\\phi$). A physical model is proposed to calculate\nthe in-plane angularly differential scattering cross section $d \\sigma^*/d\n\\theta$ of thin-film nanostructures with consideration of {the} structure\nfactor $S(q)$. Results reveal that higher level of short-range order can\nenhance in-plane Bragg scattering in certain wavelengths and directions\ncorresponding to rich and sharp peaks in {the} structure factor $S(q)$, which\ncan further modify morphology-dependent-like resonances of an individual\nscatterer {and leads } to {large} improvement of absorptivity in thin films.\nBesides, the comparison results show that SHU structures exhibit better\nintegrated absorption ($IA$) enhancement than both HD and periodic structures.\nAnd there is a transition of local-order phase between hexagonal lattice{s} and\nsquare lattice{s for SHU structures}, leading to an optimal absorption\nperformance when $\\chi$ is around 0.5 of interest. The present study paves a\nway in controlling light absorption and scattering using novel disordered\nnanostructures.",
        "positive": "Flux superperiods and periodicity transitions in quantum Hall\n  interferometers: For strongly screened Coulomb interactions, quantum Hall interferometers can\noperate in a novel regime: the intrinsic energy gap can be larger than the\ncharging energy, and addition of flux quanta can occur without adding\nquasi-particles. We show that flux superperiods are possible, and reconcile\ntheir appearance with the Byers-Yang theorem. We explain that the observation\nof anyonic statistical phases is possible by tuning to the transition from a\nregime with constant chemical potential to a regime with constant particle\ndensity, where a flux superperiod changes to a periodicity with one flux\nquantum at a critical magnetic field strength."
    },
    {
        "anchor": "Piezoelectricity in monolayer hexagonal boron nitride: Two-dimensional (2D) hexagonal boron nitride (hBN) is a wide-bandgap van der\nWaals crystal with a unique combination of properties, including exceptional\nstrength, large oxidation resistance at high temperatures and optical\nfunctionalities. Furthermore, in recent years hBN crystals have become the\nmaterial of choice for encapsulating other 2D crystals in a variety of\ntechnological applications, from optoelectronic and tunnelling devices to\ncomposites. Monolayer hBN, which has no center of symmetry, has been predicted\nto exhibit piezoelectric properties, yet experimental evidence is lacking.\nHere, by using electrostatic force microscopy, we observed this effect as a\nstrain-induced change in the local electric field around bubbles and creases,\nin agreement with theoretical calculations. No piezoelectricity was found in\nbilayer and bulk hBN, where the centre of symmetry is restored. These results\nadd piezoelectricity to the known properties of monolayer hBN, which makes it a\ndesirable candidate for novel electromechanical and stretchable optoelectronic\ndevices, and pave a way to control the local electric field and carrier\nconcentration in van der Waals heterostructures via strain. The experimental\napproach used here also shows a way to investigate the piezoelectric properties\nof other materials on the nanoscale by using electrostatic scanning probe\ntechniques.",
        "positive": "Effects of Zeroline and Ferrimagnetic Fluctuation on Nuclear Magnetic\n  Resonance for Dirac Electrons in Molecular Conductor alpha-(BEDT-TTF)2I3: We re-examine the wave function of two-dimensional massless Dirac electron in\nalpha-(BEDT-TTF)2I3 consisting of four molecules A, A', B and C in a unit cell,\nusing a tight-binding model. We find zerolines in the Brillouin zone, on which\nthe component of the wave function becomes zero for B or C sites. The\nzerolines, which are bounded by two Dirac points at k0 and pass through the M-\nor Y-points, result in a fact that the density of states of the B site exhibits\nno the Van Hove singularity near the energy of the Dirac points. By taking\naccount of the on-site Coulomb interaction within the random phase\napproximation, we examine the spin fluctuation in order to investigate\nproperties of the nuclear magnetic resonance for temperatures T > 50K. In the\nregion for 100 < T < 300K, it is shown that the Knight sift for B-site\nmonotonously decreases with decreasing temperature, owing to lack of the Van\nHove singularity, while it shows a maximum for the other sites (A, A' and C\nsites). In the region for 50 < T < 100K, it is shown that the Knight sift is\nconvex downward and the Korringa ratio increases with decreasing temperature\nfor B-site. Such a behavior originates from the ferrimagnetic spin fluctuation\nrelated to the zerolines. These results are consistent with those of the\nnuclear magnetic resonance experiments."
    },
    {
        "anchor": "Magnetization reversal of thin ferromagnetic elements with surface\n  anisotropy: The magnetization reversal process in thin-film ferromagnetic elements with\nsurface anisotropy of various shapes and sizes is investigated by means of\nnumerical simulation. The dependence of the perpendicular and in-plane\nhysteresis loops on the element thickness and the value of the surface\nanisotropy constant is obtained. For sufficiently large values of the surface\nanisotropy constant the magnetization reversal of thin-film elements is shown\nto occur due to the nucleation of the buckling mode. For an elongated\nrectangular element the nucleation field of the buckling mode is proportional\nto the absolute value of the surface anisotropy constant, and inversely\nproportional to the element thickness.",
        "positive": "Variationally optimized orbital approach to trions in two-dimensional\n  materials: In this work, trions in two-dimensional (2D) space are studied by variational\nmethod with trial wavefunctions being constructed by linear combinations of 2D\nslater-type orbitals (STOs). Via this method, trion energy levels and\nwavefunctions can be calculated efficiently with fairly good accuracy. We first\napply this method to study trion energy levels in a 2D hydrogen-like system\nwith respect to a wide range of mass ratios and screening lengths. We find that\nthe ground-state trion is bound for the whole parameter range, and an\nexcited-state trion with antisymmetric permutation of electrons with finite\nangular momentum is bound for large electron-hole mass ratios or long screening\nlengths. The binding energies of ground-state trions calculated by the present\nmethod agree well with those calculated by more sophisticated but\ncomputationally-demanding methods. We then calculate trion states in various\nmonolayer transition metal dichalcogenides (TMDCs) by using this method with\nthe inclusion of electron-hole exchange (EHX) interaction. For TMDCs, we found\nthat the effect of EHX can be significant in determining the trion binding\nenergy and the possible existence of stable excited-state trions."
    },
    {
        "anchor": "Spin wave-driven variable-phase mutual synchronization in spin Hall\n  nano-oscillators: Spin-orbit torque can drive auto-oscillations of propagating spin wave (PSW)\nmodes in nano-constriction spin Hall nano-oscillators (SHNOs). These modes\nallow both long-range coupling and the potential of controlling its phase --\ncritical aspect for nano-magnonics, spin wave logic, and Ising machines. Here,\nwe demonstrate PSW-driven variable-phase coupling between two nano-constriction\nSHNOs and study how their separation and the PSW wave vector impact their\nmutual synchronization. In addition to ordinary in-phase mutual\nsynchronization, we observe, using both electrical measurements and\nphase-resolved $\\mu-$Brillouin Light Scattering microscopy, mutual\nsynchronization with a phase that can be tuned from 0 to $\\pi$ using the drive\ncurrent or the applied field. Micromagnetic simulations corroborate the\nexperiments and visualize how the PSW patterns in the bridge connecting the two\nnano-constrictions govern the coupling. These results advance the capabilities\nof mutually synchronized SHNOs and open up new possibilities for applications\nin spin wave logic, unconventional computing, and Ising Machines.",
        "positive": "Spin transport in graphene/transition metal dichalcogenide\n  heterostructures: Since its discovery, graphene has been a promising material for spintronics:\nits low spin-orbit coupling, negligible hyperfine interaction, and high\nelectron mobility are obvious advantages for transporting spin information over\nlong distances. However, such outstanding transport properties also limit the\ncapability to engineer active spintronics, where strong spin-orbit coupling is\ncrucial for creating and manipulating spin currents. To this end, transition\nmetal dichalcogenides, which have larger spin-orbit coupling and good interface\nmatching, appear to be highly complementary materials for enhancing the\nspin-dependent features of graphene while maintaining its superior charge\ntransport properties. In this review, we present the theoretical framework and\nthe experiments performed to detect and characterize the spin-orbit coupling\nand spin currents in graphene/transition metal dichalcogenide heterostructures.\nSpecifically, we will concentrate on recent measurements of Hanle precession,\nweak antilocalization and the spin Hall effect, and provide a comprehensive\ntheoretical description of the interconnection between these phenomena."
    },
    {
        "anchor": "A continuous-wave and pulsed X-band electron spin resonance spectrometer\n  operating in ultra-high vacuum for the study of low dimensional spin\n  ensembles: We report the development of a continuous-wave and pulsed X-band electron\nspin resonance (ESR) spectrometer for the study of spins on ordered surfaces\ndown to cryogenic temperatures. The spectrometer operates in ultra-high vacuum\nand utilizes a half-wavelength microstrip line resonator realized using\nepitaxially grown copper films on single crystal Al$_2$O$_3$ substrates. The\none-dimensional microstrip line resonator exhibits a quality factor of more\nthan 200 at room temperature, close to the upper limit determined by radiation\nlosses. The surface characterizations of the copper strip of the resonator by\natomic force microscope, low-energy electron diffraction, and scanning\ntunneling microscope show that the surface is atomically clean, flat, and\nsingle crystalline. Measuring the ESR spectrum at 15 K from a few nm thick\nmolecular film of YPc$_2$, we find a continuous-wave ESR sensitivity of $2.6\n\\cdot 10^{11}~\\text{spins}/\\text{G} \\cdot \\text{Hz}^{1/2}$ indicating that a\nsignal-to-noise ratio of $3.9~\\text{G} \\cdot \\text{Hz}^{1/2}$ is expected from\na monolayer of YPc$_2$ molecules. Advanced pulsed ESR experimental capabilities\nincluding dynamical decoupling and electron-nuclear double resonance are\ndemonstrated using free radicals diluted in a glassy matrix.",
        "positive": "Majorana fermion fingerprints in spin-polarised scanning tunneling\n  microscopy: We calculate the spatially resolved tunneling conductance of topological\nsuperconductors (TSCs) based on ferromagnetic chains, measured by means of\nspin-polarised scanning tunneling microscopy (SPSTM). Our analysis reveals\nnovel signatures of MFs arising from the interplay of their strongly\nanisotropic spin-polarisation and the magnetisation content of the tip. We\nfocus on the deep Yu-Shiba-Rusinov (YSR) limit where only YSR bound states\nlocalised in the vicinity of the adatoms govern the low-energy as also the\ntopological properties of the system. Under these conditions, we investigate\nthe occurence of zero/finite bias peaks (ZBPs/FBPs) for a single or two coupled\nTSC chains forming a Josephson junction. Each TSC can host up to two Majorana\nfermions (MFs) per edge if chiral symmetry is preserved. Here we retrieve the\nconductance for all the accessible configurations of the MF number of each\nchain. Our results illustrate innovative spin-polarisation-sensitive\nexperimental routes for arresting the MFs by either restoring or splitting the\nZBP in a predictable fashion via: i) weakly breaking chiral symmetry, e.g. by\nthe SPSTM tip itself or by an external Zeeman field and ii) tuning the\nsuperconducting phase difference of the TSCs, which is encoded in the\n4$\\pi$-Josephson coupling of neighbouring MFs."
    },
    {
        "anchor": "The Thermopower of Quantum Chaos: The thermovoltage of a chaotic quantum dot is measured using a current\nheating technique. The fluctuations in the thermopower as a function of\nmagnetic field and dot shape display a non-Gaussian distribution, in agreement\nwith simulations using Random Matrix Theory. We observe no contributions from\nweak localization or short trajectories in the thermopower.",
        "positive": "Spin tunneling properties in mesoscopic magnets: effects of a magnetic\n  field: The tunneling of a giant spin at excited levels is studied theoretically in\nmesoscopic magnets with a magnetic field at an arbitrary angle in the easy\nplane. Different structures of the tunneling barriers can be generated by the\nmagnetocrystalline anisotropy, the magnitude and the orientation of the field.\nBy calculating the nonvacuum instanton solution explicitly, we obtain the\ntunnel splittings and the tunneling rates for different angle ranges of the\nexternal magnetic field ($\\theta_{H}=\\pi/2$ and $\\pi/2<\\theta_{H}<\\pi$). The\ntemperature dependences of the decay rates are clearly shown for each case. It\nis found that the tunneling rate and the crossover temperature depend on the\norientation of the external magnetic field. This feature can be tested with the\nuse of existing experimental techniques."
    },
    {
        "anchor": "Performance of Solution Processed Carbon Nanotube Field Effect\n  Transistors with Graphene Electrodes: This work evaluates the performance of carbon nanotube field effect\ntransistors (CNTFET) using few layer graphene as the contact electrode\nmaterial. We present the experimental results obtained on the barrier height at\nCNT graphene junction using temperature dependent IV measurements. The\nestimated barrier height in our devices for both holes and electrons is close\nto zero or slightly negative indicating the Ohmic contact of graphene with the\nvalence and conduction bands of CNTs. In addition, we also report that there is\nno correlation between the barrier height and thickness of graphene.",
        "positive": "Microscopic Calculation of Spin Torques and Forces: Spin torques, that is, effects of conduction electrons on magnetization\ndynamics, are calculated microscopically in the first order in spatial gradient\nand time derivative of magnetization. Special attention is paid to the\nso-called \\beta-term and the Gilbert damping, \\alpha, in the presence of\nelectrons' spin-relaxation processes, which are modeled by quenched magnetic\nimpurities. Two types of forces that the electric/spin current exerts on\nmagnetization are identified based on a general formula relating the force to\nthe torque."
    },
    {
        "anchor": "Multi-ultraflatbands tunability and effect of spin-orbit coupling in\n  twisted bilayer transition metal dichalcogenides: Ultraflatbands that have been theoretically and experimentally detected in a\nbunch of van der Waals stacked materials showing some peculiar properties, for\ninstance, highly localized electronic states and enhanced electron-electron\ninteractions. In this Letter, using an accurate tight-binding model, we study\nthe formation and evolution of ultraflatbands in transition metal\ndichalcogenides (TMDCs) under low rotation angles. We find that, unlike in\ntwisted bilayer graphene, ultraflatbands exist in TMDCs for almost any small\ntwist angles and their wave function becomes more localized when the rotation\nangle decreases. Lattice relaxation, pressure and local deformation can tune\nthe width of the flatbands, as well as their localization. Furthermore, we\ninvestigate the effect of spin-orbit coupling on the flatbands and discover\nspin/orbital/valley locking at the minimum of the conduction band at the K\npoint of the Brillouin zone. The ultraflatbands found in TMDCs with a range of\nrotation angle below $7^\\circ$, may provide an ideal platform to study strongly\ncorrelated states.",
        "positive": "Network model for higher-order topological phases: We introduce a two-dimensional network model that realizes a higher-order\ntopological phase (HOTP). We find that in the HOTP the bulk and boundaries of\nthe system are gapped, and a total of 16 corner states are protected by the\ncombination of a four-fold rotation, a phase-rotation, and a particle-hole\nsymmetry. In addition, the model exhibits a strong topological phase at a point\nof maximal coupling. This behavior is in opposition to conventional network\nmodels, which are gapless at this point. By introducing the appropriate\ntopological invariants, we show how a point group symmetry can protect a\ntopological phase in a network. Our work provides the basis for the realization\nof HOTP in alternative experimental platforms implementing the network model."
    },
    {
        "anchor": "Coexistence of four-band nodal rings and triply-degenerate nodal points\n  in centrosymmetric metal diborides: Topological metals with protected band-crossing points have been attracting\ngreat interest. Here we report novel topological band features in a family of\nmetal diboride materials. Using first- principles calculations, we show that\nthese materials are metallic, and close to Fermi level, there appears\ncoexistence of one pair of nodal rings and one pair of triply-degenerate nodal\npoints (TNPs). The nodal ring here is distinct from the previously studied ones\nin that its formation requires four entangled bands, not just two as in\nprevious cases, hence it is termed as a four-band nodal ring (FNR). Remarkably,\nwe show that FNR features Dirac-cone-like surface states, in contrast to the\nusual drumhead surface states for two-band nodal rings. Due to the presence of\ninversion symmetry, the TNP here is also different from those discussed\npreviously in inversion-asymmetric systems. Especially, when spin-orbit\ncoupling is included, the TNP here transforms into a novel Dirac point that is\nclose to the borderline between the type-I and type-II Dirac point categories.\nWe discuss their respective symmetry protections, and construct effective\nmodels for their characterization. The large linear energy range (> 2 eV) in\nthese materials should facilitate the experimental detection of the signatures\nof these nontrivial band crossings.",
        "positive": "Observation of quasi-ballistic thermal transport of surface\n  phonon-polaritons over hundreds of micrometres: Long-distance propagation of heat carriers is essential for efficient heat\ndissipation in microelectronics. However, in dielectric nanomaterials, the\nprimary heat carriers - phonons - can propagate ballistically only for hundreds\nof nanometres, which limits their heat conduction efficiency. Theory predicts\nthat surface phonon-polaritons (SPhPs) can overcome this limitation and conduct\nheat without dissipation for hundreds of micrometres. In this work, we\nexperimentally demonstrate such long-distance heat transport by SPhPs. Using\nthe 3$\\omega$ technique, we measure the in-plane thermal conductivity of SiN\nnanomembranes for different heater-sensor distances (100 and 200 $\\mu$m),\nmembrane thicknesses (30 - 200 nm), and temperatures (300 - 400 K). We find\nthat in contrast with thick membranes, thin nanomembranes support heat\nconduction by SPhPs, as evidenced by an increase in the thermal conductivity\nwith temperature. Remarkably, the thermal conductivity measured 200 $\\mu$m away\nfrom the heater are consistently higher than that measured 100 $\\mu$m closer.\nThis result suggests that heat conduction by SPhPs is quasi-ballistic over at\nleast hundreds of micrometres. Thus, our findings show that SPhPs can enhance\nheat dissipation in polar nanomembranes and find applications in thermal\nmanagement, near-field radiation, and polaritonics."
    },
    {
        "anchor": "Dispersive Readout of a Few-Electron Double Quantum Dot with Fast rf\n  Gate-Sensors: We report the dispersive charge-state readout of a double quantum dot in the\nfew-electron regime using the in situ gate electrodes as sensitive detectors.\nWe benchmark this gate-sensing technique against the well established quantum\npoint contact (QPC) charge detector and find comparable performance with a\nbandwidth of 10 MHz and an equivalent charge sensitivity of 6.3 x 10-3 e/ \\sqrt\nHz. Dispersive gate-sensing alleviates the burden of separate charge detectors\nfor quantum dot systems and promises to enable readout of qubits in scaled-up\narrays.",
        "positive": "Magnetic field control of photon echo in the electron-trion system:\n  Shuffling of coherences between optically accessible and inaccessible states: We report on magnetic field induced oscillations of the photon echo signal\nfrom negatively charged excitons in a CdTe/(Cd,Mg)Te semiconductor quantum\nwell. The oscillatory signal is due to Larmor precession of the electron spin\nabout a transverse magnetic field and depends sensitively on the polarization\nconfiguration of the exciting and refocusing pulses. The echo amplitude can be\nfully tuned from maximum down to zero depending on the time delay between the\ntwo pulses and the magnetic field strength. The results are explained in terms\nof the optical Bloch equations accounting for the spin level structure of\nelectron and trion."
    },
    {
        "anchor": "Mirror winding number and helical edge modes in honeycomb lattice with\n  hopping-energy texture: We illustrate possible topological phases in honeycomb lattice with textures\nin electron hopping energy between nearest-neighboring sites and show that they\nare characterized by the mirror winding number intimately related to the chiral\n(or sublattice) symmetry. Analytic wave functions of zero-energy edge modes in\nribbon geometry are provided, which are classified into even and odd sectors\nwith respect to the mirror operation with the mirror plane perpendicular to the\nedge, and evolve into the topological helical edge states at finite momenta.\nIntriguingly our results demonstrate that in order to achieve the topological\nphase one can decorate the edge in a way adaptive to the bulk hopping texture.\nThis paves a new way to tailoring graphene in the topological point of view.",
        "positive": "Dynamic nuclear polarization at the edge of a two-dimensional electron\n  gas: We have used gated GaAs/AlGaAs heterostructures to explore nonlinear\ntransport between spin-resolved Landau level (LL) edge states over a submicron\nregion of two-dimensional electron gas (2DEG). The current I flowing from one\nedge state to the other as a function of the voltage V between them shows\ndiode-like behavior---a rapid increase in I above a well-defined threshold V_t\nunder forward bias, and a slower increase in I under reverse bias. In these\nmeasurements, a pronounced influence of a current-induced nuclear spin\npolarization on the spin splitting is observed, and supported by a series of\nNMR experiments. We conclude that the hyperfine interaction plays an important\nrole in determining the electronic properties at the edge of a 2DEG."
    },
    {
        "anchor": "Revealing topological Dirac fermions at the surface of strained HgTe\n  thin films via Quantum Hall transport spectroscopy: We demonstrate evidences of electronic transport via topological Dirac\nsurface states in a thin film of strained HgTe. At high perpendicular magnetic\nfields, we show that the electron transport reaches the quantum Hall regime\nwith vanishing resistance. Furthermore, quantum Hall transport spectroscopy\nreveals energy splittings of relativistic Landau levels specific to coupled\nDirac surface states. This study provides new insights in the quantum Hall\neffect of topological insulator (TI) slabs, in the cross-over regime between\ntwo- and three-dimensional TIs, and in the relevance of thin TI films to\nexplore novel circuit functionalities in spintronics and quantum\nnanoelectronics.",
        "positive": "Dirac-Electrons-Mediated Magnetic Proximity Effect in Topological\n  Insulator / Magnetic Insulator Heterostructures: The possible realization of dissipationless chiral edge current in a\ntopological insulator / magnetic insulator heterostructure is based on the\ncondition that the magnetic proximity exchange coupling at the interface is\ndominated by the Dirac surface states of the topological insulator. Here we\nreport a polarized neutron reflectometry observation of Dirac electrons\nmediated magnetic proximity effect in a bulk-insulating topological insulator\n(Bi$_{0.2}$Sb$_{0.8}$)$_{2}$Te$_{3}$ / magnetic insulator EuS heterostructure.\nWe are able to maximize the proximity induced magnetism by applying an\nelectrical back gate to tune the Fermi level of topological insulator to be\nclose to the charge neutral point. A phenomenological model based on\ndiamagnetic screening is developed to explain the suppressed proximity induced\nmagnetism at high carrier density. Our work paves the way to utilize the\nmagnetic proximity effect at the topological insulator/magnetic insulator\nhetero-interface for low-power spintronic applications."
    },
    {
        "anchor": "Nonperturbative Renormalization Group Function for Quantum Hall Plateau\n  Transitions Imposed by Global Symmetries: As a unified theory of integer and fractional quantum Hall plateau\ntransitions, a nonperturbative theory of the two-parameter scaling\nrenormalization group function is presented. By imposing global symmetries\nknown as ``the law of corresponding states'', we seek a possible form of\nrenormalization group flows. Asking for consistency with the result from\nweak-localization perturbation theory, such restriction is so intense that we\ncan analytically determine its concrete form. Accordingly, the critical\nexponent $\\nu$ and the irrelevant scaling index $y$ are obtained analytically\nand turn out to be irrational. Their values ($\\nu\\approx 2.1$, $y\\approx 0.3$)\nagree favorably well with experiments and numerics.",
        "positive": "Conductance of a quantum point contact based on spin-density-functional\n  theory: We present full quantum mechanical conductance calculations of a quantum\npoint contact (QPC) performed in the framework of the density functional theory\n(DFT) in the local spin-density approximation (LDA). We show that a\nspin-degeneracy of the conductance channels is lifted and the total conductance\nexhibits a broad plateau-like feature at 0.5*2e^{2}/h. The lifting of the\nspin-degeneracy is a generic feature of all studied QPC structures (both very\nshort and very long ones; with the lengths in the range 40<l<500 nm). The\ncalculated conductance also shows a hysteresis for forward- and backward sweeps\nof the gate voltage. These features in the conductance can be traced to the\nformation of weakly coupled quasi-bound states (magnetic impurities) inside the\nQPC (also predicted in previous DFT-based studies). A comparison of obtained\nresults with the experimental data shows however, that while the spin-DFT based\n\"first-principle\" calculations exhibits the spin polarization in the QPC, the\ncalculated conductance clearly does not reproduce the 0.7 anomaly observed in\nalmost all QPCs of various geometries. We critically examine major features of\nthe standard DFT-based approach to the conductance calculations and argue that\nits inability to reproduce the 0.7 anomaly might be related to the infamous\nderivative discontinuity problem of the DFT leading to spurious\nself-interaction errors not corrected in the standard LDA. Our results indicate\nthat the formation of the magnetic impurities in the QPC might be an artefact\nof the LDA when localization of charge is expected to occur. We thus argue that\nan accurate description of the QPC structure would require approaches that go\nbeyond the standard DFT+LDA schemes."
    },
    {
        "anchor": "Spin-polarized transport in helical membranes due to spin-orbit coupling: The spin-dependent electron transmission through a helical membrane with\naccount of linear spin-orbit interaction has been investigated by numerically\nsolving the Schr\\\"odinger equation in cylindrical coordinates . It is shown\nthat the spin precession is affected by the magnitude of geometric parameters\nand chirality of the membrane. This effect is also explained analytically by\nusing the perturbation theory in the weak coupling regime. In the strong\ncoupling regime, the current spin polarization is evident when the number of\nthe open modes in leads is larger than that of the open channels in the\nmembrane. Moreover, we find that the chirality of the helical membrane can\ndetermine the orientation of current spin polarization. Therefore, one may get\ntotally opposite spin currents from the helical membranes rolled against\ndifferent directions.",
        "positive": "Enhanced longevity of the spin helix in low-symmetry quantum wells: In a semiconductor, collective excitations of spin textures usually decay\nrather fast due to D'yakonov-Perel' spin relaxation. The latter arises from\nspin-orbit coupling, which induces wave-vector-dependent spin rotations that,\nin conjunction with random disorder scattering, generate spin decoherence.\nHowever, symmetries occurring under certain conditions can prevent the\nrelaxation of particular homogeneous and inhomogeneous spin textures. The\ninhomogeneous spin texture, termed as persistent spin helix, is especially\nappealing as it enables us to manipulate the spin orientation while retaining a\nlong spin lifetime. Recently, it was predicted that such symmetries can be\nrealized in zinc-blende two-dimensional electron gases if at least two\ngrowth-direction Miller indices agree in modulus and the coefficients of the\nRashba and linear Dresselhaus spin-orbit couplings are suitably matched [PRL\n117, 236801 (2016)]. In the present paper, we systematically analyze the impact\nof the symmetry-breaking cubic Dresselhaus spin-orbit coupling, which\ngenerically coexists in these systems, on the stability of the emerging spin\nhelices with respect to the growth direction. We find that, as an interplay\nbetween orientation and strength of the effective magnetic field induced by the\ncubic Dresselhaus terms, the spin relaxation is weakest for a low-symmetry\ngrowth direction that can be well approximated by a [225] lattice vector. These\nquantum wells yield a 30\\% spin-helix lifetime enhancement compared to\n[001]-oriented electron gases and, remarkably, require a negligible Rashba\ncoefficient. The rotation axis of the corresponding spin helix is only slightly\ntilted out of the quantum-well plane. This makes the experimental study of the\nspin-helix dynamics readily accessible for conventional optical spin\norientation measurements where spins are excited and detected along the\nquantum-well growth direction."
    },
    {
        "anchor": "Cotunneling signatures of Spin-Electric coupling in frustrated\n  triangular molecular magnets: The ground state of frustrated (antiferromagnetic) triangular molecular\nmagnets is characterized by two total-spin $S =1/2$ doublets with opposite\nchirality. According to a group theory analysis [M. Trif \\textit{et al.}, Phys.\nRev. Lett. \\textbf{101}, 217201 (2008)] an external electric field can\nefficiently couple these two chiral spin states, even when the spin-orbit\ninteraction (SOI) is absent. The strength of this coupling, $d$, is determined\nby an off-diagonal matrix element of the dipole operator, which can be\ncalculated by \\textit{ab-initio} methods [M. F. Islam \\textit{et al.}, Phys.\nRev. B \\textbf{82}, 155446 (2010)]. In this work we propose that\nCoulomb-blockade transport experiments in the cotunneling regime can provide a\ndirect way to determine the spin-electric coupling strength. Indeed, an\nelectric field generates a $d$-dependent splitting of the ground state\nmanifold, which can be detected in the inelastic cotunneling conductance. Our\ntheoretical analysis is supported by master-equation calculations of quantum\ntransport in the cotunneling regime. We employ a Hubbard-model approach to\nelucidate the relationship between the Hubbard parameters $t$ and $U$, and the\nspin-electric coupling constant $d$. This allows us to predict the regime in\nwhich the coupling constant $d$ can be extracted from experiment.",
        "positive": "Theory of photoexcited and thermionic emission across a two-dimensional\n  graphene-semiconductor Schottky junction: This paper is devoted to photocarrier transport across a two-dimensional\ngraphene-semiconductor Schottky junction. We study linear response to\nmonochromatic light with excitation energy well below the semiconductor band\ngap. The operation mechanism relies on both photoelectric and thermionic\nemission from graphene to a two-dimensional semiconductor under continuous\nillumination and zero bias. Due to the thermalization bottleneck for low-energy\ncarriers in graphene, the photoelectric contribution is found to dominate the\nphotoresponse at near-infrared excitation frequencies and below. The extended\nthermalization time provides an interesting opportunity to facilitate the\ninterlayer photocarrier transport bypassing the thermalization stage. As a\nresult, the total photoresponsivity rapidly increases with excitation\nwavelength making graphene-semiconductor junctions attractive for\nphotodetection at the telecommunication frequency."
    },
    {
        "anchor": "Superconducting single-charge transistor in a tunable dissipative\n  environment: We study a superconducting single-charge transistor, where the coherence of\nCooper pair tunneling is destroyed by the coupling to a tunable dissipative\nenvironment. Sequential tunneling and cotunneling processes are analyzed to\nconstruct the shape of the conductance peaks and their dependence on the\ndissipation and temperature. Unexpected features are found due to a cross-over\nbetween two distinct regimes, one `environment-assisted' the other\n`environment-dominated'. Several of the predictions have been confirmed by\nrecent experiments. The model and results apply also to the dynamics of\nJosephson junction quantum bits on a conducting ground plane, thus explaining\nthe influence of dissipation on the coherence.",
        "positive": "Spin-fluctuation and spin-relaxation effects of single adatoms from\n  first principles: Single adatoms offer an exceptional playground for studying magnetism and its\nassociated dynamics at the atomic scale. Here we review recent results on\nsingle adatoms deposited on metallic substrates, based on time-dependent\ndensity functional theory. First we analyze quantum zero-point\nspin-fluctuations (ZPSF) as calculated from the fluctuation-dissipation\ntheorem, and show how they affect the magnetic stability by modifying the\nmagnetic anisotropy energy. We also assess the impact of ZPSF in the limit of\nsmall hybridization to the substrate characteristic of semi-insulating\nsubstrates, connecting to recent experimental investigations where magnetic\nstability of a single adatom was achieved for the first time. Secondly, we\ninspect further the dynamics of single adatoms by considering the longitudinal\nand transverse spin-relaxation processes, whose time-scales are analyzed and\nrelated to the underlying electronic structure of both the adatom and the\nsubstrate. Thirdly, we analyze spin-fluctuation modes of paramagnetic adatoms,\ni.e., adatoms where the Stoner criterion for magnetism is almost fulfilled.\nInterestingly, such modes can develop well-defined peaks in the meV range,\ntheir main characteristics being determined by two fundamental electronic\nproperties, namely the Stoner parameter and the density of states at the Fermi\nlevel. Furthermore, simulated inelastic scanning tunneling spectroscopy curves\nreveal that these spin-fluctuation modes can be triggered by tunneling\nelectrons, opening up potential applications also for paramagnetic adatoms.\nLastly, an overview of the outstanding issues and future directions is given."
    },
    {
        "anchor": "Anisotropy of excitation and relaxation of photogenerated Dirac\n  electrons in graphene: We investigate the polarization dependence of the carrier excitation and\nrelaxation in epitaxial multilayer graphene. Degenerate pump-probe experiments\nwith a temporal resolution of 30 fs are performed for different rotation angles\nof the pump-pulse polarization with respect to the polarization of the probe\npulse. A pronounced dependence of the pump-induced transmission on this angle\nis found. It reflects a strong anisotropy of the pump-induced occupation of\nphotogenerated carriers in momentum space even though the band structure is\nisotropic. Within 150 fs after excitation an isotropic carrier distribution is\nestablished. Our observations imply the predominant role of collinear\nscattering preserving the initially optically generated anisotropy in the\ncarrier distribution. The experiments are well described by microscopic time-,\nmomentum, and angle-resolved modelling, which allows us to unambiguously\nidentify non-collinear carrier-phonon scattering to be the main relaxation\nmechanism giving rise to an isotropic distribution in the first hundred fs\nafter optical excitation.",
        "positive": "Quantum Spin Hall Effect and Topologically Invariant Chern Numbers: We present a topological description of quantum spin Hall effect (QSHE) in a\ntwo-dimensional electron system on honeycomb lattice with both intrinsic and\nRashba spin-orbit couplings. We show that the topology of the band insulator\ncan be characterized by a $2\\times 2$ traceless matrix of first Chern integers.\nThe nontrivial QSHE phase is identified by the nonzero diagonal matrix elements\nof the Chern number matrix (CNM). A spin Chern number is derived from the CNM,\nwhich is conserved in the presence of finite disorder scattering and spin\nnonconserving Rashba coupling. By using the Laughlin's gedanken experiment, we\nnumerically calculate the spin polarization and spin transfer rate of the\nconducting edge states, and determine a phase diagram for the QSHE."
    },
    {
        "anchor": "Nanosecond-scale magneto-exciton energy oscillations in quantum wells: We report on the experimental evidence for a nanosecond time-scale spin\nmemory based on nonradiative excitons. The effect manifests itself in\nmagnetic-field-induced oscillations of the energy of the optically active\n(radiative) excitons. The oscillations detected by a spectrally-resolved\npump-probe technique applied to a GaAs/AlGaAs quantum well structure in a\ntransverse magnetic field persist over a time scale, which is orders of\nmagnitude longer than the characteristic decoherence time in the system. The\neffect is attributed to the spin-dependent electron-electron exchange\ninteraction of the optically active and inactive excitons. The spin relaxation\ntime of the electrons belonging to nonradiative excitons appears to be much\nlonger than the hole spin relaxation time.",
        "positive": "Universal optimal transmission of light through disordered materials: We experimentally demonstrate increased transmission of light through\nstrongly scattering materials. Wavefront shaping is used to selectively couple\nlight to the open transport channels in the material, resulting in an increase\nof up to 44% in the total transmission. The results for each of several\nhundreds of experimental runs are in excellent quantitative agreement with\nrandom matrix theory. Extrapolating our measurements to the limit of perfect\nwavefront shaping, we find a universal transmission of 2/3, regardless of the\nthickness of the sample."
    },
    {
        "anchor": "Semiclassical dynamics and transport of the Dirac spin: A semiclassical theory of spin dynamics and transport is formulated using the\nDirac electron model. This is done by constructing a wavepacket from the\npositive-energy electron band, and studying its structure and center of mass\nmotion. The wavepacket has a minimal size equal to the Compton wavelength, and\nhas self-rotation about the average spin angular momentum, which gives rise to\nthe spin magnetic moment. Geometric gauge structure in the center of mass\nmotion provides a natural explanation of the spin-orbit coupling and various\nYafet terms. Applications of the spin-Hall and spin-Nernst effects are\ndiscussed.",
        "positive": "Domain-wall Magnetic-texture dependent Creep Motion driven by\n  Spin-transfer Torques: We explore the contributions of adiabatic and non-adiabatic spin-transfer\ntorques (STT) of a spin-polarized current to the thermally activated creep\nmotion of domain-walls in a thin (Ga,Mn)(As,P) film with perpendicular\nanisotropy. For a domain-wall transverse to current, the non-adiabatic STT is\nfound to act as an external magnetic field. Close to the compensation between\nthese two terms, the adiabatic contribution is strongly enhanced. The\ndomain-wall velocity may be both increased or reduced by the adiabatic STT,\nwhich we associate to variations of creep pinning energy barrier with\ndomain-wall magnetic texture. Far from compensation, the contribution of\nadiabatic STT is negligible. Field and current driven domain-wall motion\npresent common universal behaviors described by the quenched Edwards Wilkinson\nuniversality class."
    },
    {
        "anchor": "Spin inertia and polarization recovery in quantum dots: Role of pumping\n  strength and resonant spin amplification: Spin inertia measurements are a novel experimental tool to study long-time\nspin relaxation processes in semiconductor nanostructures. We develop a theory\nof the spin inertia effect for resident electrons and holes localized in\nquantum dots. We consider the spin orientation by short optical pulses with\narbitrary pulse area and detuning from the trion resonance. The interaction\nwith an external longitudinal magnetic field and the hyperfine interaction with\nthe nuclear spin bath is considered in both the ground and excited (trion)\nstates of the quantum dots. We analyze how the spin inertia signal depends on\nthe magnetic field (polarization recovery) and on the modulation frequency of\nthe helicity of the pump pulses as well as on their power and detuning. In\nparticular, we elaborate how approaching the saturation limit of the spin\npolarization influences the measurements. The quantitative description of spin\ninertia measurements will enable the determination of the parameters of spin\ndynamics such as the spin relaxation times in the ground and excited states and\nthe parameters of the hyperfine interaction. Finally, we predict the emergence\nof resonant spin amplification due to the transverse components of the nuclear\nspin fluctuations, which manifests itself as oscillations of the spin\npolarization as a function of the longitudinal magnetic field.",
        "positive": "Temperature dependence of spin currents in one- and three-dimensional\n  insulators: The temperature dependence of spin currents in insulators at the finite\ntemperature near zero Kelvin is theoretically studied. The spin currents are\ncarried by Jordan-Wigner fermions and magnons in one- and three- dimensional\ninsulators. The quasiparticle description of one-dimensional spin systems is\nvalid only in the finite temperature near zero Kelvin. These spin currents are\ngenerated by the external magnetic field gradient along the quantization axis\nand also by the two-particle interaction gradient. In one-dimensional\ninsulators, quantum fluctuations are strong and the spin current carried by\nJordan-Wigner fermions shows the stronger dependence on temperatures than the\none by magnons."
    },
    {
        "anchor": "Field emission characteristics of InSb patterned nanowires: InSb nanowire arrays with different geometrical parameters, diameter and\npitch, are fabricated by top-down etching process on Si(100) substrates. Field\nemission properties of InSb nanowires are investigated by using a\nnano-manipulated tungsten probe-tip as anode inside the vacuum chamber of a\nscanning electron microscope. Stable field emission current is reported, with a\nmaximum intensity extracted from a single nanowire of about 1$\\mu A$,\ncorresponding to a current density as high as 10$^4$ A/cm$^2$. Stability and\nrobustness of nanowire is probed by monitoring field emission current for about\nthree hours. By tuning the cathode-anode separation distance in the range 500nm\n- 1300nm, the field enhancement factor and the turn-on field exhibit a\nnon-monotonic dependence, with a maximum enhancement $\\beta \\simeq $ 78 and a\nminimum turn-on field $E_{ON} \\simeq$ 0.033 V/nm for a separation d =900nm. The\nreduction of spatial separation between nanowires and the increase of diameter\ncause the reduction of the field emission performance, with reduced field\nenhancement ($\\beta <$ 60) and increased turn-on field ($E_{ON} \\simeq $ 0.050\nV/nm). Finally, finite element simulation of the electric field distribution in\nthe system demonstrates that emission is limited to an effective area near the\nborder of the nanowire top surface, with annular shape and maximum width of 10\nnm.",
        "positive": "Machine learning enables completely automatic tuning of a quantum device\n  faster than human experts: Device variability is a bottleneck for the scalability of semiconductor\nquantum devices. Increasing device control comes at the cost of a large\nparameter space that has to be explored in order to find the optimal operating\nconditions. We demonstrate a statistical tuning algorithm that navigates this\nentire parameter space, using just a few modelling assumptions, in the search\nfor specific electron transport features. We focused on gate-defined quantum\ndot devices, demonstrating fully automated tuning of two different devices to\ndouble quantum dot regimes in an up to eight-dimensional gate voltage space. We\nconsidered a parameter space defined by the maximum range of each gate voltage\nin these devices, demonstrating expected tuning in under 70 minutes. This\nperformance exceeded a human benchmark, although we recognise that there is\nroom for improvement in the performance of both humans and machines. Our\napproach is approximately 180 times faster than a pure random search of the\nparameter space, and it is readily applicable to different material systems and\ndevice architectures. With an efficient navigation of the gate voltage space we\nare able to give a quantitative measurement of device variability, from one\ndevice to another and after a thermal cycle of a device. This is a key\ndemonstration of the use of machine learning techniques to explore and optimise\nthe parameter space of quantum devices and overcome the challenge of device\nvariability."
    },
    {
        "anchor": "Photoemission of Bi$_2$Se$_3$ with Circularly Polarized Light: Probe of\n  Spin Polarization or Means for Spin Manipulation?: Topological insulators are characterized by Dirac cone surface states with\nelectron spins aligned in the surface plane and perpendicular to their momenta.\nRecent theoretical and experimental work implied that this specific spin\ntexture should enable control of photoelectron spins by circularly polarized\nlight. However, these reports questioned the so far accepted interpretation of\nspin-resolved photoelectron spectroscopy. We solve this puzzle and show that\nvacuum ultraviolet photons (50-70 eV) with linear or circular polarization\nprobe indeed the initial state spin texture of Bi$_2$Se$_3$ while circularly\npolarized 6 eV low energy photons flip the electron spins out of plane and\nreverse their spin polarization. Our photoemission calculations, considering\nthe interplay between the varying probing depth, dipole selection rules and\nspin-dependent scattering effects involving initial and final states explain\nthese findings, and reveal proper conditions for light-induced spin\nmanipulation. This paves the way for future applications of topological\ninsulators in opto-spintronic devices.",
        "positive": "Electronic Band Structure of Wurtzite GaP Nanowires via Resonance Raman\n  Spectroscopy: Raman measurements are performed on defect-free wurzite GaP nanowires.\nResonance Raman measurements are carried out over the excitation energy range\nbetween 2.19 and 2.71 eV. Resonances at 2.38 eV and 2.67 eV of the E1(LO) mode\nand at 2.67 eV of the A1(LO) are observed. The presence of these intensity\nresonances clearly demonstrates the existence of energy states with Gamma_9hh\nand Gamma_7V (Gamma_7C) symmetries of the valence (conduction) band and allows\nto measure WZ phase GaP band energies at the Gamma point. In addition, we have\ninvestigated temperature dependent resonant Raman measurements, which allowed\nus to extrapolate the zero temperature values of Gamma point energies, along\nwith the crystal field and spin-orbit splitting energies. Above results provide\na feedback for refining available theoretical calculations to derive the\ncorrect wurtzite III-V semiconductor band structure."
    },
    {
        "anchor": "Magnetization of a D.C. biased quantum dot: Using a quantum generalization of the Onsager principle of microscopic\nreversibility, the magnetization of a system in a non-equilibrium steady state\nquantum dot is formulated as a response of the interaction energy to an\nexternal field. This formulation permits a direct and compact computation of\nthe steady-state magnetization of a non-equilibrium quantum dot as a\ndifferential of the interaction energy. Unlike the direct computation of the\nmagnetization using perturbative Keldysh methods, this approach does not\nrequire the use of a point splitting procedure. Our results nevertheless\nsupport earlier calculations made in the limit of zero field, and they support\nthe survival of strong coupling to arbitrarily large voltages, both at zero\nfield, and under the conditions where the chemical potential difference $eV$\nbecomes equal to the spin-flip energy in a field $eV = g \\mu_{B}B$.",
        "positive": "Simulating spin systems with Majorana networks: With the discovery of Majorana quasiparticles in semiconductor-superconductor\nhybrid structures, topologically protected qubits have emerged as a promising\ncontender for quantum information processing. While the construction of a\nuniversal quantum computer with topological protection likely requires\nsignificant advances in materials science, intermediate-scale devices are\nnearly within the reach of current technology. As a near-term milestone for\ntopological qubits, we propose a network of topological superconductors as a\nsimulator of a large variety of quantum spin systems, including those with\nfrustration. Our proposal is founded on existing technology, combining\nadvantages of semiconducting and superconducting qubits. We identify local\nmeasurement protocols that give access to information about ground and excited\nstates as well as dynamic correlations. The topological protection of the\nqubits results in longer coherence times, and relaxation to the groundstate can\nbe controlled by coupling the network an external bath. We conclude by pointing\nout specific applications of the quantum simulator, e.g., spin liquids, quantum\ncriticality, and thermalization."
    },
    {
        "anchor": "Engineering decoherence in Josephson persistent-current qubits: We discuss the relaxation and dephasing rates that result from the control\nand the measurement setup itself in experiments on Josephson persistent-current\nqubits. For control and measurement of the qubit state, the qubit is\ninductively coupled to electromagnetic circuitry. We show how this system can\nbe mapped on the spin-boson model, and how the spectral density of the bosonic\nbath can be derived from the electromagnetic impedance that is coupled to the\nqubit. Part of the electromagnetic environment is a measurement apparatus\n(DC-SQUID), that is permanently coupled to the single quantum system that is\nstudied. Since there is an obvious conflict between long coherence times and an\nefficient measurement scheme, the measurement process is analyzed in detail for\ndifferent measurement schemes. We show, that the coupling of the measurement\napparatus to the qubit can be controlled in situ. Parameters that can be\nrealized in experiments today are used for a quantitative evaluation, and it is\nshown that the relaxation and dephasing rates that are induced by the\nmeasurement setup can be made low enough for a time-resolved study of the\nquantum dynamics of Josephson persistent-current qubits. Our results can be\ngeneralized as engineering rules for the read-out of related qubit systems.",
        "positive": "A Green-function approach to transport phenomena in quantum pumps: We present a general treatment to study transport phenomena in systems\ndescribed by tight-binding Hamiltonians coupled to reservoirs and with one or\nmore time-periodic potentials. We apply this treatment to the study of\ntransport phenomena in a double barrier structure with one and two harmonic\npotentials. Among other properties, we discuss the origin of the sign of the\nnet current."
    },
    {
        "anchor": "Fractal energy gaps and topological invariants in hBN/Graphene/hBN\n  double moir\u00e9 systems: We calculate the electronic structure in quasiperiodic double-moir\\'e systems\nof graphene sandwiched by hexagonal boron nitride, and identify the topological\ninvariants of energy gaps. We find that the electronic spectrum contains a\nnumber of minigaps, and they exhibit a recursive fractal structure similar to\nthe Hofstadter butterfly when plotted against the twist angle. Each of the\nenergy gaps can be characterized by a set of integers, which are associated\nwith an area in the momentum space. The corresponding area is geometrically\ninterpreted as a quasi Brillouin zone, which is a polygon enclosed by multiple\nBragg planes of the composite periods and can be uniquely specified by the\nplain wave projection in the weak potential limit.",
        "positive": "Electric-Dipole Spin Resonances: Resonance phenomena in solids generally fall into two distinct classes,\nelectric and magnetic, driven, respectively, by the $E$ and $H$ components of\nthe electromagnetic wave incident on the solid. The canonical examples of the\ntwo types of resonances are the electron cyclotron resonance (CR) and the\nelectron paramagnetic resonance (EPR), originating from the electron orbital\nand spin degrees of freedom, respectively. The behavior becomes considerably\nmore interesting (and more complicated) in the presence of the spin-orbital\ninteraction. In this case, a more general type of resonance may occur, which is\ndriven by the electric excitation mechanism and involves the spin degrees of\nfreedom. Such electric-dipole spin resonance (EDSR) may occur at the spin\nexcitation frequency or at a combination of the orbital and spin frequencies,\nspanning a wide bandwidth. The EDSR phenomenon, first predicted by Rashba\n(1960), has been probed experimentally in 3D solids with different crystal\nsymmetries, as well as in low-dimensional systems (heterojunctions, inversion\nlayers, dislocations and impurity states). Due to its electric dipole origin,\nthe EDSR features a relatively high intensity, which may exceed by orders of\nmagnitude the EPR intensity. This review summarizes the work on EDSR prior to\n1991, laying out the theoretical framework and discussing different\nexperimental systems in which the EDSR-related physics can be realized and\nexplored."
    },
    {
        "anchor": "Coherent multi-spin exchange coupling in a quantum-dot spin chain: Heisenberg exchange coupling between neighboring electron spins in\nsemiconductor quantum dots provides a powerful tool for quantum information\nprocessing and simulation. Although so far unrealized, extended Heisenberg spin\nchains can enable long-distance quantum information transfer and the generation\nof non-equilibrium quantum states. In this work, we implement simultaneous,\ncoherent exchange coupling between all nearest-neighbor pairs of spins in a\nquadruple quantum dot. The main challenge in implementing simultaneous exchange\ncouplings is the nonlinear and nonlocal dependence of the exchange couplings on\ngate voltages. Through a combination of electrostatic simulation and\ntheoretical modeling, we show that this challenge arises primarily due to\nlateral shifts of the quantum dots during gate pulses. Building on this\ninsight, we develop two models, which can be used to predict the confinement\ngate voltages for a desired set of exchange couplings. Although the model\nparameters depend on the number of exchange couplings desired (suggesting that\neffects in addition to lateral wavefunction shifts are important), the models\nare sufficient to enable simultaneous and independent control of all three\nexchange couplings in a quadruple quantum dot. We demonstrate two-, three-, and\nfour-spin exchange oscillations, and our data agree with simulations.",
        "positive": "Frequency-dependent magnetotransport and particle dynamics in magnetic\n  modulation systems: We analyze the dynamics of a charged particle moving in the presence of\nspatially-modulated magnetic fields. From Poincare surfaces of section and\nLiapunov exponents for characteristic trajectories we find that the fraction of\npinned and runaway quasiperiodic orbits {\\em vs}. chaotic orbits depends\nstrongly on the ratio of cyclotron radius to the structure parameters, as well\nas on the amplitude of the modulated field. We present a complete\ncharacterization of the dynamical behavior of such structures, and investigate\nthe contribution to the magnetoconductivity from all different orbits using a\nclassical Kubo formula. Although the DC conductivity of the system depends\nstrongly on the pinned and runaway trajectories, the frequency response\nreflects the topology of all different orbits, and even their unusual temporal\nbehavior."
    },
    {
        "anchor": "Excited states of defect lines in silicon: A first-principles study\n  based on hydrogen cluster analogues: Excited states of a single donor in bulk silicon have previously been studied\nextensively based on effective mass theory. However, a proper theoretical\ndescription of the excited states of a donor cluster is still scarce. Here we\nstudy the excitations of lines of defects within a single-valley spherical band\napproximation, thus mapping the problem to a scaled hydrogen atom array. A\nseries of detailed full configuration-interaction and time-dependent hybrid\ndensity-functional theory calculations have been performed to understand linear\nclusters of up to 10 donors. Our studies illustrate the generic features of\ntheir excited states, addressing the competition between formation of\ninter-donor ionic states and intra-donor atomic excited states. At short\ninter-donor distances, excited states of donor molecules are dominant, at\nintermediate distances ionic states play an important role, and at long\ndistances the intra-donor excitations are predominant as expected. The\ncalculations presented here emphasise the importance of correlations between\ndonor electrons, and are thus complementary to other recent approaches that\ninclude effective mass anisotropy and multi-valley effects. The exchange\nsplittings between relevant excited states have also been estimated for a donor\npair and for a three-donor arrays; the splittings are much larger than those in\nthe ground state in the range of donor separations between 10 and 20 nm. This\nestablishes a solid theoretical basis for the use of excited-state exchange\ninteractions for controllable quantum gate operations in silicon.",
        "positive": "Quasiparticle Andreev scattering in the $\u03bd=1/3$ fractional quantum\n  Hall regime: The scattering of exotic quasiparticles may follow different rules than\nelectrons. In the fractional quantum Hall regime, a quantum point contact (QPC)\nprovides a source of quasiparticles with field effect selectable charges and\nstatistics, which can be scattered on an 'analyzer' QPC to investigate these\nrules. Remarkably, for incident quasiparticles dissimilar to those naturally\ntransmitted across the analyzer, electrical conduction conserves neither the\nnature nor the number of the quasiparticles. In contrast with standard elastic\nscattering, theory predicts the emergence of a mechanism akin to the Andreev\nreflection at a normal-superconductor interface. Here, we observe the predicted\nAndreev-like reflection of an $e/3$ quasiparticle into a $-2e/3$ hole\naccompanied by the transmission of an $e$ quasielectron. Combining shot noise\nand cross-correlation measurements, we independently determine the charge of\nthe different particles and ascertain the coincidence of quasielectron and\nfractional hole. The present work advances our understanding on the\nunconventional behavior of fractional quasiparticles, with implications toward\nthe generation of novel quasi-particles/holes and non-local entanglements."
    },
    {
        "anchor": "Proposal for a tunable graphene-based terahertz Landau-level laser: In the presence of strong magnetic fields the electronic bandstructure of\ngraphene drastically changes. The Dirac cone collapses into discrete\nnon-equidistant Landau levels, which can be externally tuned by changing the\nmagnetic field. In contrast to conventional materials, specific Landau levels\nare selectively addressable using circularly polarized light. Exploiting these\nunique properties, we propose the design of a tunable laser operating in the\ntechnologically promising terahertz spectral range. To uncover the\nmany-particle physics behind the emission of light, we perform a fully quantum\nmechanical investigation of the non-equilibrium dynamics of electrons, phonons,\nand photons in optically pumped Landau-quantized graphene embedded into an\noptical cavity. The gained microscopic insights allow us to predict optimal\nexperimental conditions to realize a technologically promising terahertz laser.",
        "positive": "Photoconductivity in AC-driven modulated two dimensional electron gas in\n  a perpendicular magnetic field: In this work we study the microwave photoconductivity of a two-dimensional\nelectron system (2DES) in the presence of a magnetic field and a\ntwo-dimensional modulation (2D). The model includes the microwave and Landau\ncontributions in a non-perturbative exact way, the periodic potential is\ntreated perturbatively. The Landau-Floquet states provide a convenient base\nwith respect to which the lattice potential becomes time-dependent, inducing\ntransitions between the Landau-Floquet levels. Based on this formalism, we\nprovide a Kubo-like formula that takes into account the oscillatory Floquet\nstructure of the problem. The total longitudinal conductivity and resistivity\nexhibit strong oscillations, determined by $\\epsilon = \\omega / \\omega_c$ with\n$\\omega$ the radiation frequency and $\\omega_c$ the cyclotron frequency. The\noscillations follow a pattern with minima centered at $\\omega/\\omega_c =j +\n{1/2} (l-1) + \\delta $, and maxima centered at $\\omega/\\omega_c =j + {1/2}\n(l-1) - \\delta $, where $j=1,2,3.......$, $\\delta \\sim 1/5$ is a constant shift\nand $l$ is the dominant multipole contribution. Negative resistance states\n(NRS) develop as the electron mobility and the intensity of the microwave power\nare increased. These NRS appear in a narrow window region of values of the\nlattice parameter ($a$), around $a \\sim l_B$, where $l_B$ is the magnetic\nlength. It is proposed that these phenomena may be observed in artificially\nfabricated arrays of periodic scatterers at the interface of ultraclean\n$GaAs/Al_xGa_{1-x} As$ heterostructures."
    },
    {
        "anchor": "Extrinsic and Intrinsic Charge Trapping at the Graphene/Ferroelectric\n  Interface: The interface between graphene and the ferroelectric superlattice\n$\\mathrm{PbTiO_3/SrTiO_3}$ (PTO/STO) is studied. Tuning the transition\ntemperature through the PTO/STO volume fraction minimizes the adsorbates at the\ngraphene-ferroelectric interface, allowing robust ferroelectric hysteresis to\nbe demonstrated. Intrinsic charge traps from the ferroelectric surface defects\ncan adversely affect the graphene channel hysteresis, and can be controlled by\ncareful sample processing, enabling systematic study of the charge trapping\nmechanism.",
        "positive": "Scanning tunneling microscopy and spectroscopy of the electronic local\n  density of states of graphite surfaces near monoatomic step edges: We measured the electronic local density of states (LDOS) of graphite\nsurfaces near monoatomic step edges, which consist of either the zigzag or\narmchair edge, with the scanning tunneling microscopy (STM) and spectroscopy\n(STS) techniques. The STM data reveal that the $(\\sqrt{3} \\times \\sqrt{3}) R\n30^{\\circ}$ and honeycomb superstructures coexist over a length scale of 3-4 nm\nfrom both the edges. By comparing with density-functional derived nonorthogonal\ntight-binding calculations, we show that the coexistence is due to a slight\nadmixing of the two types of edges at the graphite surfaces. In the STS\nmeasurements, a clear peak in the LDOS at negative bias voltages from -100 to\n-20 mV was observed near the zigzag edges, while such a peak was not observed\nnear the armchair edges. We concluded that this peak corresponds to the\ngraphite \"edge state\" theoretically predicted by Fujita \\textit{et al.} [J.\nPhys. Soc. Jpn. {\\bf 65}, 1920 (1996)] with a tight-binding model for graphene\nribbons. The existence of the edge state only at the zigzag type edge was also\nconfirmed by our first-principles calculations with different edge\nterminations."
    },
    {
        "anchor": "Strong g-Factor Anisotropy in Hole Quantum Dots Defined in Ge/Si\n  Nanowires: We demonstrate fully tunable single and double quantum dots in a\none-dimensional hole system based on undoped Ge/Si core-shell nanowire\nheterostructures. The local hole density along the nanowire is controlled by\napplying voltages to five top gate electrodes with a periodicity of 80 nm,\ninsulated from the wire by a 20 nm-thick HfO_2 dielectric film. Low-temperature\ntransport measurements were used to investigate the magnetic field dependence\nof Coulomb blockade peaks in a single quantum dot and indicate a strongly\nanisotropic g-factor with |g_para| = 0.60 +/- 0.03 and |g_perp| < 0.12.",
        "positive": "Observation of supersymmetric pseudo-Landau levels in strained microwave\n  graphene: Using an array of coupled microwave resonators arranged in a deformed\nhoneycomb lattice, we experimentally observe the formation of pseudo-Landau\nlevels in the whole crossover from vanishing to large pseudomagnetic field\nstrength. This is achieved by utilizing an adaptable set-up in a geometry that\nis compatible with the pseudo-Landau levels at all field strengths. The adopted\napproach enables to observe fully formed flat-band pseudo-Landau levels\nspectrally as sharp peaks in the photonic density of states, and image the\nassociated wavefunctions spatially, where we provide clear evidence for a\ncharacteristic nodal structure reflecting the previously elusive supersymmetry\nin the underlying low-energy theory. In particular, we resolve the full\nsublattice polarization of the anomalous 0th pseudo-Landau level, which reveals\na deep connection to zigzag edge states in the unstrained case."
    },
    {
        "anchor": "Quantum and thermal fluctuations in the dynamics of a resistively and\n  capacitively shunted Josephson junction: We theoretically investigate the phase and voltage correlation dynamics,\nwhich includes both the deterministic contribution and stochastic fluctuations,\nunder a current noise generated by a resistor including thermal and quantum\nfluctuations in a resistively and capacitively shunted Josephson junction. An\nexternal current is found to shift and intensify the deterministic\ncontributions in phase and voltage. In addition to effects of external current,\nwe observe the relaxation of autocorrelation functions of phase and voltage,\nwhich includes the variances due to the current noise, to finite values in the\nlong-time limit. In particular, we find that the asymptotic correlations depend\non the resistance as a consequence of quantum effects. We also find an earlier\ndecay of coherence at a higher temperature in which thermal fluctuations\ndominate over quantum ones. These theoretical predictions can be tested in the\nnext future experiments.",
        "positive": "Detection of finite frequency current moments with a dissipative\n  resonant circuit: We consider the measurement of higher current moments with a dissipative\nresonant circuit, which is coupled inductively to a mesoscopic device in the\ncoherent regime. Information about the higher current moments is coded in the\nhistograms of the charge on the capacitor plates of the resonant circuit.\nDissipation is included via the Caldeira-Leggett model, and it is essential to\ninclude it in order for the charge fluctuations (or the measured noise) to\nremain finite. We identify which combination of current correlators enter the\nmeasurement of the third moment. The latter remains stable for zero damping.\nResults are illustrated briefly for a quantum point contact."
    },
    {
        "anchor": "A brief review of hybrid skin-topological effect: The finding of non-Hermitian skin effect has revolutionized our understanding\nof non-Hermitian topological phases, where the usual bulk-boundary\ncorrespondence is broken and new topological phases specific to non-Hermitian\nsystem are uncovered. Hybrid skin-topological effect (HSTE) is a class of newly\ndiscovered non-Hermitian topological states that simultaneously supports\nskin-localized topological edge states and extended bulk states. Here we\nprovide a brief review of HSTE, starting from different mechanics that have\nbeen used to realize HSTE, including non-reciprocal couplings, onsite\ngain/loss, and non-Euclidean lattice geometries. We also review some\ntheoretical developments closely related to the HSTE, including the concept of\nhigher-order non-Hermitian skin effect, parity-time symmetry engineering, and\nnon-Hermitian chiral skin effect. Finally, we summarize recent experimental\nexploration of HSTE, including its realization in electric circuits systems,\nnon-Hermitian photonic crystals, and active matter systems. We hope this review\ncan make the concept of hybrid-skin effect clearer and inspire new finding of\nnon-Hermitian topological states in higher dimensional systems.",
        "positive": "In-Plane Magnetic Field Tolerance of a Dispersive Aluminum Nanobridge\n  SQUID Magnetometer: We characterize the flux sensitivity of a dispersive 3D aluminum nanobridge\nSQUID magnetometer as a function of applied in-plane magnetic field. In zero\nfield, we observe an effective flux noise of 17 n$\\Phi_0$/Hz$^{1/2}$ with 25\nMHz of bandwidth. Flux noise increased by less than a factor of three with\nparallel magnetic fields up to 61 mT. Operation in higher fields may be\npossible by decreasing the dimensions of the shunt capacitor in the\nmagnetometer circuit. These devices are thus well suited for observing\nhigh-speed dynamics in nanoscale magnets, even in the presence of moderate bias\nmagnetic fields."
    },
    {
        "anchor": "Distribution of the transfer matrix in disordered wires: A closed expression is derived for the probability distribution of the\ntransfer matrix of a particle moving in a one-dimensional system with\ndelta-correlated, weak disorder. The change in the distribution as a function\nof wire length is described by a diffusion equation on the $SU(1,1)$ group,\nwhich is solved through the decomposition of the regular representation into\nirreducible components. The expression generalizes a number of well-known\nresults, including the distributions of the transmission coefficient and local\ndensity of states. As an application, the average single energy-level\ncontribution to the persistent current in a flux-threaded ring is derived.",
        "positive": "Out-of-plane spin-to-charge conversion at low temperatures in\n  graphene/MoTe$_2$ heterostructures: Multi-directional spin-to-charge conversion - in which spin polarizations\nwith different orientations can be converted into a charge current in the same\ndirection - has been demonstrated in low-symmetry materials and interfaces.\nThis is possible because, in these systems, spin to charge conversion can occur\nin unconventional configurations in which spin polarization and charge current\nwhere charge current, spin current and polarization do not need to be mutually\northogonal. Here, we explore, in the low temperature regime, the spin-to-charge\nconversion in heterostructures of graphene with the low-symmetry 1T' phase of\nMoTe$_2$. First, we observe the emergence of charge conversion for out-of-plane\nspins at temperatures below 100 K. This unconventional component is allowed by\nthe symmetries of both MoTe$_2$ and graphene and likely arises from spin Hall\neffect in the spin-orbit proximitized graphene. Moreover, we examine the\nlow-temperature evolution of non-local voltage signals arising from the charge\nconversion of the two in-plane spin polarizations, which have been previously\nobserved at higher temperature. As a result, we report omni-directional\nspin-to-charge conversion - for all spin polarization orientations - in\ngraphene/MoTe${_2}$ heterostructures at low temperatures."
    },
    {
        "anchor": "Quantum current enhancement effect in hybrid rings at equilibrium: Current enhancement- a novel quantum phenomena is found to occur in a\nmesoscopic hybrid ring at equilibrium. The hybrid system is described by a ring\nwith bubble which is in turn coupled to a reservoir. In the system the ring\nencloses a magnetic flux $\\Phi$ while the bubble does not enclose any flux. The\nnovelty of this work lies in the fact that while earlier current enhancement\nwas observed in non-equilibrium systems (e.g., a ring coupled to two reservoirs\nat different chemical potentials $\\mu_{1}$ and $\\mu_{2}$), herein we prove that\ncurrent enhancement can also arise in equilibrium. In addition, we show that\nthe closed system analog of our chosen open hybrid ring system violates parity\neffects. Finally, we bring to focus the discrepancy between the equilibrium\nmagnetic moment (obtained via energy eigenvalues) and that calculated from the\ncurrents in the system.",
        "positive": "1,000-Fold Enhancement of Light-Induced Magnetism in Plasmonic Au\n  Nanoparticles: Strategies for ultrafast optical control of magnetism have been a topic of\nintense research for several decades because of the potential impact in\ntechnologies such as magnetic memory, spintronics, and quantum computation, as\nwell as the opportunities for non-linear optical control and modulation in\napplications such as optical isolation and non-reciprocity. Here we report the\nfirst experimental quantification of optically induced magnetization in\nplasmonic Au nanoparticles due to the inverse Faraday effect (IFE). The induced\nmagnetic moment in nanoparticles is found to be ~1,000x larger than that\nobserved in bulk Au, and ~20x larger than the magnetic moment from optimized\nmagnetic nanoparticle colloids such as magnetite. Furthermore, the\nmagnetization and demagnetization kinetics are instantaneous within the\nsub-picosecond time resolution of our study, supporting a mechanism of coherent\ntransfer of angular momentum from the circularly polarized excitation to the\norbital angular momentum of the electron gas."
    },
    {
        "anchor": "Ultrafast valley-selective coherent optical manipulation with excitons\n  in WSe$_2$ and MoS$_2$ monolayers: Increasing the speed limits of conventional electronics requires innovative\napproaches to manipulate other quantum properties of electrons besides their\ncharge. An alternative approach utilizes the valley degree of freedom in\nlow-dimensional semiconductors. Here we demonstrate that the valley degeneracy\nof exciton energies in transition metal dichalcogenide monolayers may be lifted\nby coherent optical interactions on timescales corresponding to few tens of\nfemtoseconds. The optical Stark and Bloch-Siegert effects generated by strong\nnonresonant circularly-polarized light induce valley-selective blue shifts of\nexciton quantum levels by more than 30 meV. We show these phenomena by studying\nthe two most intensive exciton resonances in transiton metal dichalcogenide\nmonolayers and compare the results to a theoretical model, which properly\nincludes the Coulomb interaction and exciton dispersion. These results open the\ndoor for ultrafast valleytronics working at multiterahertz frequencies.",
        "positive": "Topological states and interplay between spin-orbit and Zeeman\n  interactions in a spinful Su-Schrieffer-Heeger nanowire: The interplay between the spin-orbit and Zeeman interactions acting on a\nspinful Su-Schrieffer-Heeger model is studied based on an InAs nanowire\nsubjected to a periodic gate potential along the axial direction. It is shown\nthat a nontrivial topological phase can be achieved by regulating the\nconfining-potential configuration. In the absence of the Zeeman field, we prove\nthat the topology of the chain is not affected by the Rashba spin-orbit\ninteraction due to the persisting chiral symmetry. The energies of the edge\nmodes can be manipulated by varying the magnitude and direction of the external\nmagnetic field. Remarkably, the joint effect of the two spin-related\ninteractions leads to novel edge states that appear in the gap formed by the\nanti-crossing of the bands of a finite spinful dimerized chain, and can be\nmerged into the bulk states by tilting the magnetic-field direction."
    },
    {
        "anchor": "Topological phases of a dimerized Fermi-Hubbard model for semiconductor\n  nano-lattices: Motivated by recent advances in fabricating artificial lattices in\nsemiconductors and their promise for quantum simulation of topological\nmaterials, we study the one-dimensional dimerized Fermi-Hubbard model. We show\nhow the topological phases at half-filling can be characterized by a reduced\nZak phase defined based on the reduced density matrix of each spin subsystem.\nSignatures of bulk-boundary correspondence are observed in the triplon\nexcitation of the bulk and the edge states of uncoupled spins at the\nboundaries. At quarter-filling we show that owing to the presence of the\nHubbard interaction the system can undergo a transition to the topological\nground state of the non-interacting Su-Schrieffer-Heeger model with the\napplication of a moderate-strength external magnetic field. We propose a robust\nexperimental realization with a chain of dopant atoms in silicon or\ngate-defined quantum dots in GaAs where the transition can be probed by\nmeasuring the tunneling current through the many-body state of the chain.",
        "positive": "Single atom adhesion in optimized gold nanojunctions: We study the interaction between single apex atoms in a metallic contact,\nusing the break junction geometry. By carefully 'training' our samples, we\ncreate stable junctions in which no further atomic reorganization takes place.\nThis allows us to study the relation between the so-called jump out of contact\n(from contact to tunnelling regime) and jump to contact (from tunnelling to\ncontact regime) in detail. Our data can be fully understood within a relatively\nsimple elastic model, where the elasticity k of the electrodes is the only free\nparameter. We find 5 < k < 32 N/m. Furthermore, the interaction between the two\napex atoms on both electrodes, observed as a change of slope in the tunnelling\nregime, is accounted for by the same model."
    },
    {
        "anchor": "Tunable Kondo screening in a quantum dot device: We consider electron transport along a single-mode channel which is in\ncontact, via tunnel junctions in its walls, with two quantum dots. Electron\ntunneling to and from the dots contributes to the electron backscattering, and\nthus modifies the channel conductance. If the dots carry spin, the channel\nconductance becomes temperature dependent due to the Kondo effect. The two-dot\ndevice geometry allows for a formation of S=1 localized spin due to the\nindirect exchange interaction, called Ruderman-Kittel-Kasuya-Yosida\ninteraction. This device offers a possibility to study the crossover between\nfully screened and under-screened Kondo impurity. We investigate the\nmanifestation of such crossover in the channel conductance.",
        "positive": "Correlated Insulating States at Fractional Fillings of the WS2/WSe2\n  Moir\u00e9 Lattice: Moir\\'e superlattices of van der Waals materials, such as twisted graphene\nand transitional metal dichalcogenides, have recently emerged as a fascinating\nplatform to study strongly correlated states in two dimensions, thanks to the\nstrong electron interaction in the moir\\'e minibands. In most systems, the\ncorrelated states appear when the moir\\'e lattice is filled by integer number\nof electrons per moir\\'e unit cell. Recently, correlated states at fractional\nfillings of 1/3 and 2/3 holes per moir\\'e unit cell has been reported in the\nWS2/WSe2 heterobilayer, hinting the long range nature of the electron\ninteraction. In this work, employing a scanning microwave impedance microscopy\ntechnique that is sensitive to local electrical properties, we observe a series\nof correlated insulating states at fractional fillings of the moir\\'e minibands\non both electron- and hole-doped sides in angle-aligned WS2/WSe2\nhetero-bilayers, with certain states persisting at temperatures up to 120 K.\nMonte Carlo simulations reveal that these insulating states correspond to\nordering of electrons in the moir\\'e lattice with a periodicity much larger\nthan the moir\\'e unit cell, indicating a surprisingly strong and long-range\ninteraction beyond the nearest neighbors. Our findings usher in unprecedented\nopportunities in the study of strongly correlated states in two dimensions."
    },
    {
        "anchor": "Dynamics of two coupled semiconductor spin qubits in a noisy environment: We theoretically consider the temporal dynamics of two coupled spin qubits\n(e.g., semiconductor quantum dots) driven by the inter-qubit spin-spin\ncoupling. The presence of environmental noise (e.g., charge traps, nuclear\nspins, random magnetic impurities) is accounted for by including random\nmagnetic field and random inter-qubit coupling terms in the Hamiltonian. Both\nHeisenberg coupling and Ising coupling between the spin qubits are considered,\ncorresponding respectively to exchange and capacitive gates as appropriate for\nsingle spin and singlet-triplet semiconductor qubit systems, respectively. Both\nexchange (Heisenberg) and capacitive (Ising) coupling situations can be solved\nnumerically exactly even in the presence of noise, leading to the key findings\nthat (i) the steady-state return probability to the initial state remains close\nto unity in the presence of strong noise for many, but not all, starting spin\nconfigurations, and (ii) the return probability as a function of time is\noscillatory with a characteristic noise-controlled decay toward the\nsteady-state value. We also provide results for the magnetization dynamics of\nthe coupled two-qubit system. Our predicted dynamics can be directly tested in\nthe already existing semiconductor spin qubit setups providing insight into\ntheir coherent interaction dynamics. Retention of the initial state spin memory\neven in the presence of strong environmental noise has important implications\nfor quantum computation using spin qubits.",
        "positive": "Low-Frequency Microwave Induced Quantum Oscillations in A\n  Two-Dimensional Electron System: We study the magnetoresistance of an ultrahigh mobility GaAs/AlGaAs\ntwo-dimensional electron sample in a weak magnetic field under low-frequency (f\n< 20 GHz) microwave (MW) irradiation. We observe that with decreasing MW\nfrequency, microwave induced resistance oscillations (MIRO) damp and\nmulti-photon processes become dominant. At very low MW frequency (f < 4 GHz),\nMIRO disappears gradually and a new SdH-like oscillation develops. The analysis\nindicates that the new oscillation may originate from alternating Hall-field\ninduced resistance oscillations (ac-HIRO), or can be viewed as a multi-photon\nprocess of MIRO in low MW frequency limit. Our findings bridge the\nnon-equilibrium states of MIRO and HIRO, which can be brought into a frame of\nquantum tunneling junction model."
    },
    {
        "anchor": "Magnetism in twisted triangular bilayer graphene quantum dots: Using a tight-binding model along with the mean-field Hubbard method, we\ninvestigate the effect of twisting angle on the magnetic properties of twisted\nbilayer graphene (tBLG) quantum dots (QDs) with triangular shape and zigzag\nedges. We consider such QDs in two configurations: when their initial untwisted\nstructure is a perfect AA- or AB-stacked BLG, referred to as AA- or AB-like\ndots. We find that AA-like dots exhibit an antiferromagnetic spin polarization\nfor small twist angles, which transits to a ferromagnetic spin polarization\nbeyond a critical twisting angle $\\theta_c$. Our analysis shows that $\\theta_c$\ndecreases as the dot size increases, obeying a criterion, according to which\nonce the maximum energy difference between electron and hole edge states (in\nthe single-particle picture) is less than $(U / \\gamma_0)\\, t_0$, the\nspin-polarized energy levels are aligned ferromagnetically [$U$ is the Hubbard\nparameter and $\\gamma_0$ ($t_0$) the graphene intralayer (interlayer) hopping].\nUnlike AA-like dots, AB-like dots exhibit finite magnetization for any twist\nangle. Furthermore, in the ferromagnetic polarization state, the ground net\nspin for both dot configurations agrees with prediction from Lieb's theorem.",
        "positive": "Pinning of thermal excitations at defects in artificial spin-ice dipolar\n  arrays: A theoretical investigation: In this theoretical investigation we address the effect of defects on thermal\nexcitations in square-lattice dipolar arrays. The geometry of the nanomagnets,\nadopted from recent experiments [A. Farhan \\textit{et al.}, Nature Phys.\\\n\\textbf{9} (2013) 375], allows for thermal activation at room temperature. It\nturns out that excitations can efficiently be pinned at defects. Furthermore,\nferromagnetic strings of nanomagnets that connect a pair of defects can be\nproduced; their lengths are closely related to the distance of the defects and\nthe topology of the magnetic ground-state configuration. We discuss various\ntypes of defects, all of which can be produced by microstructuring techniques."
    },
    {
        "anchor": "Diffusion-limited exciton-exciton annihilation in single-walled carbon\n  nanotubes: A time-dependent analysis: To provide physical insight into the recently observed photoluminescence\nsaturation behaviors in single-walled carbon nanotubes implying the existence\nof an upper limit of exciton densities, we have performed a time-dependent\ntheoretical study of diffusion-limited exciton-exciton annihilation in the\ngeneral context of reaction-diffusion processes, for which exact treatments\nexist. By including the radiative recombination decay as a Poissonian process\nin the exactly-solvable problem of one-dimensional diffusion-driven\ntwo-particle annihilation, we were able to correctly model the dynamics of\nexcitons as a function of time with different initial densities, which in turn\nallowed us to reproduce the experimentally observed photoluminescence\nsaturation behavior at high exciton densities. We also performed Monte Carlo\nsimulations of the purely stochastic, Brownian diffusive motion of\none-dimensional excitons, which validated our analytical results. Finally, we\nconsider the temperature-dependence of this diffusion-limited exciton-exciton\nannihilation and point out that high excitonic densities in SWNTs could be\nachieved at low temperature in an external magnetic field.",
        "positive": "Spin Transport in Quantum Spin-Orbital Liquids: Quantum spin-orbital liquids (QSOLs) are a novel phase of matter, similar to\nquantum spin liquids, with quantum fluctuations in both spin and orbital\ndegrees of freedom. We use non-equilibrium Green's function theory to study\nout-of-equilibrium spin transport in an exactly solvable QSOL model put forward\nby Yao and Lee. We find that the spin transport problem can be mapped to that\nof a free fermion problem with effective fermionic baths that have rapidly\nvarying density of states. In the gapless phase, the spin current $I_s-V_s$\nrelation is thus highly nonlinear, while in the chiral gapped phase, the spin\ncurrent conductance is quantized to be $1/2\\pi$ provided that the contacts are\nsufficiently wide. The quantized conductance is a signature of the topological\nnature of the chiral gapped QSOL."
    },
    {
        "anchor": "Role of photon recycling in perovskite solar cells: Nearly perfect photon recycling helped GaAs cells achieve the highest\nefficiency ever reported for a solar cell. Recent reports of photon recycling\nin perovskite solar cells suggest that, once optimized, it may as well achieve\nGaAs-like performance. In this paper, we show that GaAs and perovskite cells\nrecycle photons in different ways. First, although bare-perovskite has been\nshown to have lifetimes (~1us) in the radiative limit, non-radiative\nrecombination at the transport layers restricts the solar cell operation far\nbelow the \"photon-recycling\" regime. GaAs cells have no such limitation.\nSecond, even if the transport layers were optically and electrically perfect,\nthe poor mobility of the perovskite layer would still restrict the optimum\nthickness ~1um. Thus, a very high quality mirror (reflectivity >96%) is\nrequired to utilize photon-recycling. The mirror reflectivity restriction was\nfar more relaxed for the thicker (~2-3um) GaAs cells. Therefore, a nontrivial\nco-optimization of device geometry, mirror reflectivity, and material choice is\nnecessary for achieving highest theoretical efficiency anticipated for\nperovskite cells.",
        "positive": "Double-dot charge qubit and transport via dissipative cotunneling: We investigate transport through an exotic ``charge'' qubit composed of two\nstrongly capacitively coupled quantum dots (QDs), each being independently\nconnected to a side gate which in general exhibits a fluctuating electrostatic\nfield ({\\em i.e.}, Nyquist/Johnson noise). Two quantum phases are found: the\n``Kondo'' phase where an orbital-Kondo entanglement emerges and a ``local\nmoment'' phase in which the noise destroys the Kondo effect leaving the orbital\nspin unscreened and resulting in a clear suppression of the conductance. In the\nKondo realm, the transfer of charge across the setting is accompanied by\nzero-point charge fluctuations in the two dissipative environments and then the\nI-V characteristics are governed by what we call ``dissipative cotunneling''."
    },
    {
        "anchor": "Exchange coupling and current-perpendicular-to-plane giant\n  magneto-resistance of magnetic trilayers. Rigorous results within a\n  tight-binding single-band model: It is shown that the current-perpendicular-to-plane giant magneto-resistance\n(CPP-GMR) oscillations, in the ballistic regime, are strongly correlated with\nthose of the exchange coupling (J). Both the GMR and J are treated on equal\nfooting within a rigorously solvable tight-binding single-band model. The\nstrong correlation consists in sharing asymptotically the same period,\ndetermined by the spacer Fermi surface, and oscillating with varying spacer\nthickness predominantly in opposite phases.",
        "positive": "Hamiltonian Formulation of Quantum Hall Skyrmions with Hopf Term: We study the nonrelativistic nonlinear sigma model with Hopf term in this\npaper. This is an important issue beacuse of its relation to the currently\ninteresting studies in skyrmions in quantum Hall systems. We perform the\nHamiltonian analysis of this system in $CP^1$ variables. When the coefficient\nof the Hopf term becomes zero we get the Landau-Lifshitz description of the\nferromagnets. The addition of Hopf term dramatically alters the Hamiltonian\nanalysis. The spin algebra is modified giving a new structure and\ninterpretation to the system. We point out momentum and angular momentum\ngenerators and new features they bring in to the system."
    },
    {
        "anchor": "Magnetic field tuning of terahertz Dirac plasmons in graphene: Boundaries and edges of a two dimensional system lower its symmetry and are\nusually regarded, from the point of view of charge transport, as imperfections.\nHere we present a first study of the behavior of graphene plasmons in a strong\nmagnetic field that provides a different perspective. We show that the plasmon\nresonance in micron size graphene disks in a strong magnetic field splits into\nedge and bulk plasmon modes with opposite dispersion relations, and that the\nedge plasmons at terahertz frequencies develop increasingly longer lifetimes\nwith increasing magnetic field, in spite of potentially more defects close to\nthe graphene edges. This unintuitive behavior is attributed to increasing\nquasi-one dimensional field-induced confinement and the resulting suppression\nof the back-scattering. Due to the linear band structure of graphene, the\nsplitting rate of the edge and bulk modes develops a strong doping dependence,\nwhich differs from the behavior of traditional semiconductor two-dimensional\nelectron gas (2DEG) systems. We also observe the appearance of a higher order\nmode indicating an anharmonic confinement potential even in these well-defined\ncircular disks. Our work not only opens an avenue for studying the physics of\ngraphene edges, but also supports the great potential of graphene for tunable\nterahertz magneto-optical devices.",
        "positive": "Electronic transport in one-dimensional Floquet topological insulators\n  via topological and nontopological edge states: Based on probing electronic transport properties we propose an experimental\ntest for the recently discovered rich topological phase diagram of\none-dimensional Floquet topological insulators with Rashba spin-orbit\ninteraction [Kennes \\emph{et al.}, Phys. Rev. B {\\bf 100}, 041103(R) (2019)].\nUsing the Keldysh-Floquet formalism we compute electronic transport properties\nof these nanowires, where we propose to couple the leads in such a way, as to\nprimarily address electronic states with a large weight at one edge of the\nsystem. By tuning the Fermi energy of the leads to the center of the\ntopological gap we are able to directly address the topological edge states,\ngranting experimental access to the topological phase diagram. Surprisingly,\nwhen tuning the lead Fermi energy to special values in the bulk which coincide\nwith extremal points of the dispersion relation, we find additional peaks of\nsimilar magnitude to those caused by the topological edge states. These peaks\nreveal the presence of continua of states centered around aforementioned\nextremal points whose wavefunctions are linear combinations of delocalized bulk\nstates and exponentially localized edge states, where the ratio of edge- to\nbulk-state amplitude is maximal at the extremal point of the dispersion. We\ndiscuss the transport properties of these \\emph{non-topological edge states},\nexplain their emergence in terms of an intuitive yet quantitative physical\npicture and discuss their relationship with Van Hove singularities in the bulk\nof the system. The mechanism giving rise to these states is not specific to the\nmodel we consider here, suggesting that they may be present in a wide class of\none-dimensional systems."
    },
    {
        "anchor": "On the detection of zero-point current and voltage fluctuations: It this paper we consider various methods for measuring current fluctuations.\nIt is shown, that the {\\it temporal} zero-point fluctuations of current are\nmeasurable in a natural set-ups.",
        "positive": "Kinetic theory of fluctuations in conducting systems: We propose an effective field theory describing the time dependent\nfluctuations of electrons in conducting systems, generalizing the well known\nkinetic theory of fluctuations. On several examples, we show its equivalence,\n(when quantum corrections are neglected) to a microscopic quantum mechanical\nnon-linear $\\sigma$-model theory. We apply then the theory to analyze the\neffects of strong electron-electron and electron-phonon scattering on the\nstatistics of current fluctuations. We find that if the electron-electron\nscattering length is much shorter than the transport mean free path the higher\ncumulants of current are parametrically enhanced."
    },
    {
        "anchor": "Ballistic side jump motion of electrons and holes in semiconductor\n  quantum wells: We investigate the ballistic motion of electrons and holes in III-V\nsemiconductor quantum wells with spin-orbit coupling and a homogeneous in-plane\nelectric field. As a result of a non-perturbative treatment of both of these\ninfluences, particle wave packets undergo a pronounced side jump perpendicular\nto the field direction. For wave packets of sufficient width the amplitude of\nthis motion can be estimated analytically and increases with decreasing field\nstrength. We discuss the scaling behavior of the effect and some if its\nexperimental implications",
        "positive": "Ellipsometry studies of Si/Ge superlattices with embedded Ge dots: In this paper, we present an analysis for treating the spectroscopic\nellipsometry response of Si/Ge superlattices (SL) with embedded Ge dots.\nSpectroscopic ellipsometry (SE) measurement at room temperature was used to\ninvestigate optical and electronic properties of Si/Ge SL which were grown on\nsilicon (Si) wafers having <111> crystallographic orientation. The results of\nthe SE analysis between 200 nm and 1000 nm indicate that the SL system can\neffectively be described using interdiffusion/intermixing model by assuming a\nmulticrystalline Si and Si1-xGex intermixing layers. The electronic transitions\ndeduced from analysis reveal Si, Ge and alloying related critical energy\npoints."
    },
    {
        "anchor": "Equivalence between the mobility edge of electronic transport on\n  disorderless networks and the onset of chaos via intermittency in\n  deterministic maps: We exhibit a remarkable equivalence between the dynamics of an intermittent\nnonlinear map and the electronic transport properties (obtained via the\nscattering matrix) of a crystal defined on a double Cayley tree. This strict\nanalogy reveals in detail the nature of the mobility edge normally studied near\n(not at) the metal-insulator transition in electronic systems. We provide an\nanalytical expression for the conductance as function of system size that at\nthe transition obeys a q-exponential form. This manifests as power-law decay or\nfew and far between large spike oscillations according to different kinds of\nboundary conditions.",
        "positive": "Magnetic Moment and Band Structure Analysis of Fe, Co, Ni-modified\n  Graphene-nano- ribbon: Magnetic properties and band characteristics of graphene-nano-ribbon (GNR)\nmodified by Fe, Co, and Ni were analyzed by the first principles DFT\ncalculation. Typical unit cell is [C32H2Fe1], [C32H2Co1] and [C32H2Ni1]\nrespectively. The most stable spin state was Sz=4/2 for Fe-modified GNR,\nwhereas Sz=3/2 for Co-case and Sz=2/2 for Ni-case. Atomic magnetic moment of\nFe, Co and Ni were 3.63, 2.49 and 1.26 {\\mu}B, which were reduced values than\nthat of atomic Hund-rule due to magnetic coupling with graphene network. There\nis a possibility for a ferromagnetic Fe, Co and Ni spin array through an\ninteraction with carbon pi-conjugated spin system. By expanding a unit cell of\nCo-modified case as [C96H6Co3], ferromagnetic like spin state and ferrimagnetic\nlike one were compared. It was concluded that ferromagnetic state was more\nstable magnetic state. Band calculations of Co-modified case show half-metal\nlike structure with relatively large band gap (0.55eV) for up-spin, whereas\nsmall gap (0.05eV) for down-spin. This suggested a capability of spintronics\napplication like a spin fiter."
    },
    {
        "anchor": "Infrared study of carrier scattering mechanism in ion-gated graphene: We performed infrared transmission experiment on ion-gel gated graphene and\nmeasured carrier scattering rate g as function of carrier density n over wide\nrange up to n=2E13 cm-2. The g exhibits a rapid decreases along with the gating\nfollowed by persistent increases on further carrier doping. This behavior of\ng(n) demonstrates that carrier is scattered dominantly by the two scattering\nmechanisms, namely, charged impurity (CI) scattering and short-range disorder\n(SR) scattering, with additional minor scattering from substrate phonon (SPP).\nWe can determine the absolute strengths of all the scattering channels by\nfitting the g(n) data and unveils the complete n-dependent map of the\nscattering mechanisms g(n)=gCI(n)+gSR(n)+gSPP(n). The gCI(n) and gSR(n) are\nlarger than those of SiO2$-gated graphene by 1.8 times, which elucidates the\ndual role of the ion-gel layer as a CI-scatterer and simultaneously a\nSR-scatterer to graphene. Additionally we show that freezing of IG at low-T\n(~200 K) does not cause any change to the carrier scattering.",
        "positive": "Scrambling and Gate Effects in Realistic Quantum Dots: We evaluate the magnitude of two important mesoscopic effects using a\nrealistic model of typical quantum dots. ``Scrambling'' and ``gate effect'' are\ndefined as the change in the single-particle spectrum due to added electrons or\ngate-induced shape deformation, respectively. These two effects are\ninvestigated systematically in both the self-consistent Kohn-Sham (KS) theory\nand a Fermi liquid-like Strutinsky approach. We find that the genuine\nscrambling effect is small because the potential here is smooth. In the KS\ntheory, a key point is the implicit inclusion of residual interactions in the\nspectrum; these dominate and make scrambling appear larger. Finally, the gate\neffect is comparable in the two cases and, while small, is able to cause\ngate-induced spin transitions."
    },
    {
        "anchor": "On-chip resonantly-driven quantum emitter with enhanced coherence: Advances in nanotechnology provide techniques for the realisation of\nintegrated quantum-optical circuits for on-chip quantum information\nprocessing(QIP). The indistinguishable single photons, required for such\ndevices can be generated by parametric down-conversion, or from quantum\nemitters such as colour centres and quantum dots(QDs). Among these,\nsemiconductor QDs offer distinctive capabilities including on-demand operation,\ncoherent control, frequency tuning and compatibility with semiconductor\nnanotechnology. Moreover, the coherence of QD photons can be significantly\nenhanced in resonance fluorescence(RF) approaching at its best the coherence of\nthe excitation laser. However, the implementation of QD RF in scalable on-chip\ngeometries remains challenging due to the need to suppress stray laser photons.\nHere we report on-chip QD RF coupled into a single-mode waveguide with\nnegligible resonant laser background and show that the coherence is enhanced\ncompared to off-resonant excitation. The results pave the way to a novel class\nof integrated quantum-optical devices for on-chip QIP with embedded\nresonantly-driven quantum emitters.",
        "positive": "Perpendicular electric field drives Chern transitions and layer\n  polarization changes in Hofstadter bands: Moir\\'e superlattices engineer band properties and enable observation of\nfractal energy spectra of Hofstadter butterfly. Recently, correlated-electron\nphysics hosted by flat bands in small-angle moir\\'e systems has been at the\nforeground. However, the implications of moir\\'e band topology within the\nsingle-particle framework are little explored experimentally. An outstanding\nproblem is understanding the effect of band topology on Hofstadter physics,\nwhich does not require electron correlations. Our work experimentally studies\nChern state switching in the Hofstadter regime using twisted double bilayer\ngraphene (TDBG), which offers electric field tunable topological bands, unlike\ntwisted bilayer graphene. Here we show that the nontrivial topology reflects in\nthe Hofstadter spectra, in particular, by displaying a cascade of Hofstadter\ngaps that switch their Chern numbers sequentially while varying the\nperpendicular electric field. Our experiments together with theoretical\ncalculations suggest a crucial role of charge polarization changing\nconcomitantly with topological transitions in this system. Layer polarization\nis likely to play an important role in the topological states in few-layer\ntwisted systems. Moreover, our work establishes TDBG as a novel Hofstadter\nplatform with nontrivial magnetoelectric coupling."
    },
    {
        "anchor": "Characterization and reduction of microfabrication-induced decoherence\n  in superconducting quantum circuits: Many superconducting qubits are highly sensitive to dielectric loss, making\nthe fabrication of coherent quantum circuits challenging. To elucidate this\nissue, we characterize the interfaces and surfaces of superconducting coplanar\nwaveguide resonators and study the associated microwave loss. We show that\ncontamination induced by traditional qubit lift-off processing is particularly\ndetrimental to quality factors without proper substrate cleaning, while\nroughness plays at most a small role. Aggressive surface treatment is shown to\ndamage the crystalline substrate and degrade resonator quality. We also\nintroduce methods to characterize and remove ultra-thin resist residue,\nproviding a way to quantify and minimize remnant sources of loss on device\nsurfaces.",
        "positive": "Correlated disorder induced anomalous transport in magnetically doped\n  topological insulators: We examine the transport properties of magnetically doped topological\ninsulator (TI) thin films subject to correlated non-magnetic disorder. For the\ndisorder we choose a quasi-periodic potential with a random phase. We restrict\nthe disorder to a central region, which is coupled to two leads in a clean\nquantum spin Hall insulator (QSHI) state and concentrate on different\norientations of the quasi-periodicity in the two-dimensional central region. In\nthe case of a diagonally oriented or purely longitudinal quasi-periodicity we\nfind different topological Anderson insulator (TAI) phases, with a quantum\nanomalous Hall insulator (QAHI), a quantum spin Chern insulator (QSCI), or a\nQSHI phase being realized before the Anderson insulation takes over at large\ndisorder strength. Quantized transport from extended bulk states is found for\ndiagonal quasi-periodicity in addition to the above TAI phases that are also\nobserved for the case of uncorrelated disorder. For a purely transverse\norientation of the quasi-periodicity the emerging QSHI and QSCI phases persist\nto arbitrarily strong disorder potential. These topological phase transitions\n(except to the Anderson insulator phase), can be understood from a self\nconsistent Born approximation."
    },
    {
        "anchor": "Phonon-assisted tunneling in an isolated double dot system: Phonon-assisted tunneling rates are evaluated for a well isolated double dot\nsystem defined in a GaAs semiconductor heterostructure of finite thickness. A\nseparable model for the confining potential allows accurate determinations of\ndoublet electron wavefunctions and energies. It is found that at small doublet\nenergies the piezoelectric rates due to flexural modes give the dominant\ncontribution. For small slab thicknesses the predicted rates are up to two\norders of magnitude higher than for very thick slabs.",
        "positive": "Electrical transport through carbon nanotube junctions created by\n  mechanical manipulation: Using an atomic force microscope we have created nanotube junctions such as\nbuckles and crossings within individual single-wall metallic carbon nanotubes\nconnected to metallic electrodes. The electronic transport properties of these\nmanipulated structures show that they form electronic tunnel junctions. The\nconductance shows power-law behavior as a function of bias voltage and\ntemperature, which can be well modeled by a Luttinger liquid model for\ntunneling between two nanotube segments separated by the manipulated junction."
    },
    {
        "anchor": "Dimensional Crossover of Dilute Neon inside Infinitely Long\n  Single-Walled Carbon Nanotubes Viewed from Specific Heats: A simple formula for coordinates of carbon atoms in a unit cell of a\nsingle-walled nanotube (SWNT) is presented and the potential of neon (Ne)\ninside an infinitely long SWNT is analytically derived under the assumption of\npair-wise Lennard-Jones potential between Ne and carbon atoms. Specific heats\nof dilute Ne inside infinitely long (5, 5), (10, 10), (15, 15) and (20, 20)\nSWNT's are calculated at different temperatures. It is found that Ne inside\nfour kinds of nanotubes exhibits 3-dimensional (3D) gas behavior at high\ntemperature but different behaviors at low temperature: Ne inside (5, 5)\nnanotube behaves as 1D gas but inside (10, 10), (15, 15), and (20, 20)\nnanotubes behaves as 2D gas. Furthermore, at ultra low temperature, Ne inside\n(5, 5) nanotube still displays 1D behavior but inside (10, 10), (15, 15), and\n(20, 20) nanotubes behaves as lattice gas.",
        "positive": "Spin pumping by parametrically excited exchange magnons: We experimentally show that exchange magnons can be detected using a\ncombination of spin pumping and inverse spin-Hall effect (iSHE) proving its\nwavelength integrating capability down to the sub-micrometer scale. The magnons\nwere injected in a ferrimagnetic yttrium iron garnet film by parametric pumping\nand the iSHE-induced voltage was detected in an attached Pt layer. The role of\nthe density, wavelength, and spatial localization of the magnons for the spin\npumping efficiency is revealed. This study opens the field of the magnon-based\ninformation processing to magnons with nano-scale wavelengths."
    },
    {
        "anchor": "Crossover from Coulomb blockade to quantum Hall effect in suspended\n  graphene nanoribbons: Suspended graphene nano-ribbons formed during current annealing of suspended\ngraphene flakes have been investigated experimentally. Transport measurements\nshow the opening of a transport gap around charge neutrality due to the\nformation of \"Coulomb islands\", coexisting with quantum Hall conductance\nplateaus appearing at moderate values of magnetic field $B$. Upon increasing\n$B$, the transport gap is rapidly suppressed, and is taken over by a much\nlarger energy gap due to electronic correlations. Our observations show that\nsuspended nano-ribbons allow the investigation of phenomena that could not so\nfar be accessed in ribbons on SiO$_2$ substrates.",
        "positive": "Electrostatic and Magnetic Fields in Bilayer Graphene: We compute the transmission probability through rectangular potential\nbarriers and p-n junctions in the presence of a magnetic and electric fields in\nbilayer graphene taking into account contributions from the full four bands of\nthe energy spectrum. For energy $E$ higher than the interlayer coupling\n$\\gamma_1$ ($E > \\gamma_1$) two propagation modes are available for transport\ngiving rise to four possible ways for transmission and reflection coefficients.\nHowever, when the energy is less than the height of the barrier the Dirac\nfermions exhibit transmission resonances and only one mode of propagation is\navailable for transport. We study the effect of the interlayer electrostatic\npotential denoted by $\\delta$ and variations of different barrier geometry\nparameters on the transmission probability."
    },
    {
        "anchor": "Spatial noise correlations beyond nearest-neighbor in ${}^{28}$Si/SiGe\n  spin qubits: We detect correlations in qubit-energy fluctuations of non-neighboring qubits\ndefined in isotopically purified Si/SiGe quantum dots. At low frequencies\n(where the noise is strongest), the correlation coefficient reaches 10% for a\nnext-nearest-neighbor qubit-pair separated by 200 nm. Assigning the observed\nnoise to be of electrical origin, a simple theoretical model quantitatively\nreproduces the measurements and predicts a polynomial decay of correlations\nwith interqubit distance. Our results quantify long-range correlations of noise\ndephasing quantum-dot spin qubits arranged in arrays, essential for scalability\nand fault-tolerance of such systems.",
        "positive": "A Generalizable TCAD Framework for Silicon FinFET Spin Qubit Devices\n  with Electrical Control: We present a TCAD-based simulation framework established for quantum dot spin\nqubits in a silicon FinFET platform with all-electrical control of the spin\nstate. The framework works down to 1K and consists of a two-step simulation\nchain, from definition of the quantum dot confinement potential with DC bias\nvoltages, to calculation of microwave response electric field at qubit\nlocations using small-signal AC analysis. An average field polarization vector\nat each quantum dot is extracted via a post-processing step. We demonstrate\nfunctionality of this approach by simulation of a recently reported two-qubit\ndevice in the form of a 5-gate silicon FinFET. The impact of the number of\nholes in each quantum dot on the MW response E-field polarization direction is\nfurther investigated for this device. The framework is easily generalizable to\nstudy future multi-qubit large-scale systems."
    },
    {
        "anchor": "Mobile N\u00e9el skyrmions at room temperature: status and future: Magnetic skyrmions are topologically protected spin textures that exhibit\nmany fascinating features. As compared to the well-studied cryogenic Bloch\nskyrmions in bulk materials, we focus on the room-temperature N\\'eel skyrmions\nin thin-film systems with an interfacial broken inversion symmetry in this\narticle. Specifically, we show the stabilization, the creation, and the\nimplementation of N\\'eel skyrmions that are enabled by the electrical\ncurrent-induced spin-orbit torques. Towards the nanoscale N\\'eel skyrmions, we\nfurther discuss the challenges from both material optimization and imaging\ncharacterization perspectives.",
        "positive": "Variability Effects in Graphene: Challenges and Opportunities for Device\n  Engineering and Applications: Variability effects in graphene can result from the surrounding environment\nand the graphene material itself, which form a critical issue in examining the\nfeasibility of graphene devices for large-scale production. From the\nreliability and yield perspective, these variabilities cause fluctuations in\nthe device performance, which should be minimized via device engineering. From\nthe metrology perspective, however, the variability effects can function as\nnovel probing mechanisms, in which the 'signal fluctuations' can be useful for\npotential sensing applications. This paper presents an overview of the\nvariability effects in graphene, with emphasis on their challenges and\nopportunities for device engineering and applications. The discussion can\nextend to other thin-film, nanowire and nanotube devices with similar\nvariability issues, forming general interest in evaluating the promise of\nemerging technologies."
    },
    {
        "anchor": "Disorder-induced temperature-dependent transport in graphene: Puddles,\n  impurities, activation, and diffusion: We theoretically study the transport properties of both monolayer and bilayer\ngraphene in the presence of electron-hole puddles induced by charged impurities\nwhich are invariably present in the graphene environment. We calculate the\ngraphene conductivity by taking into account the non-mean-field two-component\nnature of transport in the highly inhomogeneous density and potential\nlandscape, where activated transport across the potential fluctuations in the\npuddle regimes coexists with regular metallic diffusive transport. The\nexistence of puddles allows the local activation at low carrier densities,\ngiving rise to an insulating temperature dependence in the conductivity of both\nmonolayer and bilayer graphene systems. We also critically study the\nqualitative similarity and the quantitative difference between monolayer and\nbilayer graphene transport in the presence of puddles. Our theoretical\ncalculation explains the non-monotonic feature of the temperature dependent\ntransport, which is experimentally generically observed in low mobility\ngraphene samples. We establish the 2-component nature (i.e., both activated and\ndiffusive) of graphene transport arising from the existence of potential\nfluctuation induced inhomogeneous density puddles. The temperature dependence\nof the graphene conductivity arises from many competing mechanisms, even\nwithout considering any phonon effects, such as thermal excitation of carriers\nfrom the valence band to the conduction band, temperature dependent screening,\nthermal activation across the potential fluctuations associated with the\nelectron-hole puddles induced by the random charged impurities in the\nenvironment, leading to very complex temperature dependence which depends both\non the carrier density and the temperature range of interest.",
        "positive": "Transport of Dirac electrons in a random magnetic field in topological\n  heterostructures: We consider the proximity effect between Dirac states at the surface of a\ntopological insulator and a ferromagnet with easy plane anisotropy, which is\ndescribed by the \\emph{XY}-model and undergoes a\nBerezinskii-Kosterlitz-Thouless (BKT) phase transition. The surface states of\nthe topological insulator interacting with classical magnetic fluctuations of\nthe ferromagnet can be mapped onto the problem of Dirac fermions in a random\nmagnetic field. However, this analogy is only partial in the presence of\nelectron-hole asymmetry or warping of the Dirac dispersion, which results in\nscreening of magnetic fluctuations. Scattering at magnetic fluctuations\ninfluences the behavior of the surface resistivity as a function of\ntemperature. Near the BKT phase transition temperature we find that the\nresistivity of surface states scales linearly with temperature and has a clear\nmaximum which becomes more pronounced as the Fermi energy decreases.\nAdditionally at low temperatures we find linear resistivity, usually associated\nwith non-Fermi liquid behavior, however here it appears entirely within the\nFermi liquid picture."
    },
    {
        "anchor": "Heat-driven spin transport in a ferromagnetic metal: As a non-magnetic heavy metal is attached to a ferromagnet, a vertically\nflowing heat-driven spin current is converted to a transverse electric voltage,\nwhich is known as the longitudinal spin Seebeck effect (SSE). If the\nferromagnet is a metal, this voltage is also accompanied by voltages from two\nother sources, i.e. the anomalous Nernst effect in both the ferromagnet and the\nproximity-induced ferromagnetic boundary layer. By properly identifying and\ncarefully separating those different effects, we find that in this pure spin\ncurrent circuit the additional spin current drawn by the heavy metal generates\nanother significant voltage by the ferromagnetic metal itself which should be\npresent in all relevant experiments.",
        "positive": "Energy dependent counting statistics in diffusive superconducting tunnel\n  junctions: We present an investigation of the energy dependence of the full charge\ncounting statistics in diffusive\nnormal-insulating-normal-insulating-superconducting junctions. It is found that\nthe current in general is transported via a correlated transfer of pairs of\nelectrons. Only in the case of strongly asymmetric tunnel barriers or energies\nmuch larger than the Thouless energy is the pair transfer uncorrelated. The\nsecond cumulant, the noise, is found to depend strongly on the applied voltage\nand temperature. For a junction resistance dominated by the tunnel barrier to\nthe normal reservoir, the differential shot noise shows a double peak feature\nat voltages of the order of the Thouless energy, a signature of an ensemble\naveraged electron-hole resonance."
    },
    {
        "anchor": "Spin polarized two-dimensional electron gas embedded in semimagnetic\n  quantum well : ground state, spin responses, spin excitations, Raman spectrum: We present theoretical aspects of spin polarized two dimensional electron gas\n(SP2DEG) which can be achieved in doped semimagnetic quantum wells. This\noriginal model system has been recently studied by magneto Raman scattering\nexperiments has given a new access to spin resolved excitations and spectrum of\nthe SP2DEG. Starting from the Diluted Magnetic Semiconductor (DMS) Hamiltonian\nin presence of the Coulomb interaction between conduction electrons, we define\nthe conditions to reach such a SP2DEG. The equilibrium state is studied at low\ntemperature; in particular a theory for the degree of spin polarization is\nderived. Dynamical spin susceptibilities are further calculated in the\nframework of a spin density functional formalism already developed in the past.\nWe then derive spin conserving and spin flip excitations dispersions using a\nrecent determination of the SP2DEG correlation energy corrected from the\nthickness of the well. The SP2DEG presents two key features: the spin flip\nwave, which existence is a direct consequence of the Coulomb interaction\nbetween the spin polarized electrons, with a dispersion and energy range\ntypical to the SP2DEG obtained in DMS, the spin density fluctuations exhibiting\na specific collective behaviour when the spin polarization is increased. The\ndissipation spectrum through these excitations is studied in detail. Particular\nattention is given to the spectrum determined by resonant Raman scattering. We\nshow, indeed, that the latter gives unique access to the spin-fluctuations\nspectrum of the SP2DEG.",
        "positive": "InGaN/GaN Multi-Quantum-Well and Light-Emitting Diode Based on\n  V-pit-Shaped GaN Grown on Patterned Sapphire Substrate: V-pit-defects in GaN-based light-emitting diodes induced by dislocations are\nconsidered beneficial to electroluminescence because they relax the strain in\nInGaN quantum wells and also enhance the hole lateral injection through\nsidewall of V-pits. In this paper, regularly arranged V-pits are formed on\nc-plane GaN grown by metal organic vapor phase epitaxy on conventional c-plane\ncone-patterned sapphire substrates. The size of V-pits and area of flat GaN can\nbe adjusted by changing growth temperature. Five pairs of InGaN/GaN\nmulti-quantumwell and also a light-emitting diode structure are grown on this\nV-pit-shaped GaN. Two peaks around 410 nm and 450 nm appearing in both\nphotoluminescence and cathodeluminescence spectra are from the semipolar\nInGaN/GaN multi-quantum-well on sidewalls of V-pits and cplane InGaN/GaN\nmulti-quantum-well, respectively. In addition, dense bright spots can be\nobserved on the surface of light-emitting diode when it works under small\ninjection current, which are believed owing to the enhanced hole injection\naround V-pits."
    },
    {
        "anchor": "New generation of moir\u00e9 superlattices in doubly aligned\n  hBN/graphene/hBN heterostructures: The specific rotational alignment of two-dimensional lattices results in a\nmoir\\'e superlattice with a larger period than the original lattices and allows\none to engineer the electronic band structure of such materials. So far,\ntransport signatures of such superlattices have been reported for graphene/hBN\nand graphene/graphene systems. Here we report moir\\'e superlattices in fully\nhBN encapsulated graphene with both the top and the bottom hBN aligned to the\ngraphene. In the graphene, two different moir\\'e superlattices form with the\ntop and the bottom hBN, respectively. The overlay of the two superlattices can\nresult in a third superlattice with a period larger than the maximum period (14\nnm) in the graphene/hBN system, which we explain in a simple model. This new\ntype of band structure engineering allows one to artificially create an even\nwider spectrum of electronic properties in two-dimensional materials.",
        "positive": "Goos-H\u00e4nchen-like shifts for Dirac fermions in monolayer graphene\n  barrier: We investigate the Goos-H\\\"{a}nchen-like shifts for Dirac fermions in\ntransmission through a monolayer graphene barrier. The lateral shifts, as the\nfunctions of the barrier's width and the incidence angle, can be negative and\npositive in Klein tunneling and classical motion, respectively. Due to their\nrelations to the transmission gap, the lateral shifts can be enhanced by the\ntransmission resonances when the incidence angle is less than the critical\nangle for total reflection, while their magnitudes become only the order of\nFermi wavelength when the incidence angle is larger than the critical angle.\nThese tunable beam shifts can also be modulated by the height of potential\nbarrier and the induced gap, which gives rise to the applications in\ngraphene-based devices."
    },
    {
        "anchor": "On the Kondo effect in carbon nanotubes at half halfing: In a single state of a quantum dot the Kondo effect arises due to the\nspin-degeneracy, which is present if the dot is occupied with one electron (N =\n1). The eigenstates of a carbon nanotube quantum dot possess an additional\norbital degeneracy leading to a four-fold shell pattern. This additional\ndegeneracy increases the possibility for the Kondo effect to appear. We revisit\nthe Kondo problem in metallic carbon nanotubes by linear and non-linear\ntransport measurement in this regime, in which the four-fold pattern is\npresent. We have analyzed the ground state of CNTs, which were grown by\nchemical vapor deposition, at filling N = 1, N = 2, and N = 3. Of particular\ninterest is the half-filled shell, i.e. N = 2. In this case, the ground state\nis either a paired electron state or a state for which the singlet and triplet\nstates are effectively degenerate, allowing in the latter case for the\nappearance of the Kondo effect. We deduce numbers for the effective missmatch d\nof the levels from perfect degeneracy and the exchange energy J. While d ~ 0.1\n- 0.2 (in units of level spacing) is in agreement with previous work, the\nexchange term is found to be surprisingly small: J < 0.02. In addition we\nreport on the observation of gaps, which in one case is seen at N = 3 and in\nanother is present over an extended sequence of levels.",
        "positive": "All-magnonic spin-transfer torque and domain wall propagation: The spin wave transportation through a transverse magnetic domain wall (DW)\nin a magnetic nanowire is studied. It is found that spin wave passes through a\nDW without reflection. A magnon, the quantum of the spin wave, carries opposite\nspins on the two sides of the DW. As a result, there is a spin angular momentum\ntransfer from the propagating magnons to the DW. This magnonic spin-transfer\ntorque can efficiently drive a DW to propagate in the opposite direction to\nthat of the spin wave."
    },
    {
        "anchor": "Microscopic analysis of shot-noise suppression in nondegenerate\n  diffusive conductors: We present a theoretical investigation of shot-noise suppression due to\nlong-range Coulomb interaction in nondegenerate diffusive conductors.\nCalculations make use of an ensemble Monte Carlo simulator self-consistently\ncoupled with a one-dimensional Poisson solver. We analyze the noise in a\nlightly doped active region surrounded by two contacts acting as thermal\nreservoirs. By taking the doping of the injecting contacts and the applied\nvoltage as variable parameters, the influence of elastic and inelastic\nscattering in the active region is investigated. The transition from ballistic\nto diffusive transport regimes under different contact injecting statistics is\nanalyzed and discussed. Provided significant space-charge effects take place\ninside the active region, long-range Coulomb interaction is found to play an\nessential role in suppressing the shot noise at $qU \\gg k_BT$. In the elastic\ndiffusive regime, momentum space dimensionality is found to modify the\nsuppression factor $\\gamma$, which within numerical uncertainty takes values\nrespectively of about 1/3, 1/2 and 0.7 in the 3D, 2D and 1D cases. In the\ninelastic diffusive regime, shot noise is suppressed to the thermal value.",
        "positive": "Characterization of InSb quantum wells with atomic layer deposited gate\n  dielectrics: We report magnetotransport measurements of a gated InSb quantum well (QW)\nwith high quality Al2O3 dielectrics (40 nm thick) grown by atomic layer\ndeposition. The magnetoresistance data demonstrate a parallel conduction\nchannel in the sample at zero gate voltage (Vg). A good interface between Al2O3\nand the top InSb layer ensures that the parallel channel is depleted at\nnegative Vg and the density of two-dimensional electrons in the QW is tuned by\nVg with a large ratio of 6.5x1014 m-2V-1 but saturates at large negative Vg.\nThese findings are closely related to layer structures of the QW as suggested\nby self-consistent Schrodinger-Poisson simulation and two-carrier model."
    },
    {
        "anchor": "Landau Quantization in Graphene Monolayer, Bernal Bilayer, and Bernal\n  Trilayer on Graphite Surface: Electronic properties of surface areas decoupled from graphite are studied\nusing scanning tunnelling microscopy and spectroscopy. We show that it is\npossible to identify decoupled graphene monolayer, Bernal bilayer, and Bernal\ntrilayer on graphite surface according to their tunnelling spectra in high\nmagnetic field. The decoupled monolayer and bilayer exhibit Landau quantization\nof massless and massive Dirac fermions, respectively. The substrate generates a\nsizable band gap, ~35 meV, in the Bernal bilayer, therefore, the eightfold\ndegenerate Landau level at the charge neutrality point is split into two\nvalley-polarized quartets polarized on each layer. In the decoupled Bernal\ntrilayer, we find that both massless and massive Dirac fermions coexist and its\nlow-energy band structure can be described quite well by taking into account\nonly the nearest-neighbor intra- and interlayer hopping parameters. A strong\ncorrelation between the Fermi velocity of the massless Dirac fermions and the\neffective mass of the massive Dirac fermions is observed in the trilayer. Our\nresult demonstrates that the surface of graphite provides a natural ideal\nplatform to probe the electronic spectra of graphene layers.",
        "positive": "From Coulomb blockade to the Kondo regime in a Rashba dot: We investigate the electronic transport in a quantum wire with localized\nRashba interaction. The Rashba field forms quasi-bound states which couple to\nthe continuum states with an opposite spin direction. The presence of this\nRashba dot causes Fano-like antiresonances and dips in the wire's linear\nconductance. The Fano lineshape arises from the interference between the direct\ntransmission channel along the wire and the hopping through the Rashba dot. Due\nto the confinement, we predict the observation of large charging energies in\nthe local Rashba region which lead to Coulomb-blockade effects in the transport\nproperties of the wire. Importantly, the Kondo regime can be achieved with a\nproper tuning of the Rashba interaction, giving rise to an oscillating linear\nconductance for a fixed occupation of the Rashba dot."
    },
    {
        "anchor": "Rectification and nonlinear transport in chaotic dots and rings: We investigate the nonlinear current-voltage characteristic of mesoscopic\nconductors and the current generated through rectification of an alternating\nexternal bias. To leading order in applied voltages both the nonlinear and the\nrectified current are quadratic. This current response can be described in\nterms of second order conductance coefficients and for a generic mesoscopic\nconductor they fluctuate randomly from sample to sample. Due to Coulomb\ninteractions the symmetry of transport under magnetic field inversion is broken\nin a two-terminal setup. Therefore, we consider both the symmetric and\nantisymmetric nonlinear conductances separately. We treat interactions\nself-consistently taking into account nearby gates.\n  The nonlinear current is determined by different combinations of second order\nconductances depending on the way external voltages are varied away from an\nequilibrium reference point (bias mode). We discuss the role of the bias mode\nand circuit asymmetry in recent experiments. In a photovoltaic experiment the\nalternating perturbations are rectified, and the fluctuations of the nonlinear\nconductance are shown to decrease with frequency. Their asymptotical behavior\nstrongly depends on the bias mode and in general the antisymmetric conductance\nis suppressed stronger then the symmetric conductance.\n  We next investigate nonlinear transport and rectification in chaotic rings.\nTo this extent we develop a model which combines a chaotic quantum dot and a\nballistic arm to enclose an Aharonov-Bohm flux. In the linear two-probe\nconductance the phase of the Aharonov-Bohm oscillation is pinned while in\nnonlinear transport phase rigidity is lost. We discuss the shape of the\nmesoscopic distribution of the phase and determine the phase fluctuations.",
        "positive": "Singular flat bands in the modified Haldane-Dice model: Flat bands can be divided into singular and non-singular ones according to\nthe behavior of their Bloch wave function around band-crossing points in\nmomentum space. We analyze the flat band in the Dice model, which can be tuned\nby a uniaxial strain in the zigzag direction and a Haldane-type next-nearest\nneighbor interaction, and derive the topological phase diagram of the modified\nHaldane-Dice model to obtain all band-gap closings with the central band. When\nthe central band is flat, we determine its compact localized state and classify\nits behavior at all band-touching points by means of the Hilbert-Schmidt\nquantum distance. We find that the flat band remains singular for all\nband-touching points (topological phase transitions) with a maximal quantum\ndistance and give expressions for the resulting non-contractible loop states on\nthe real-space torus."
    },
    {
        "anchor": "Cooling low-dimensional electron systems into the microkelvin regime: Two-dimensional electron gases (2DEGs) with high mobility, engineered in\nsemiconductor heterostructures host a variety of ordered phases arising from\nstrong correlations, which emerge at sufficiently low temperatures. The 2DEG\ncan be further controlled by surface gates to create quasi-one dimensional\nsystems, with potential spintronic applications. Here we address the\nlong-standing challenge of cooling such electrons to below 1$\\,$mK, potentially\nimportant for identification of topological phases and spin correlated states.\nThe 2DEG device was immersed in liquid $^3$He, cooled by the nuclear adiabatic\ndemagnetization of copper. The temperature of the 2D electrons was inferred\nfrom the electronic noise in a gold wire, connected to the 2DEG by a metallic\nohmic contact. With effective screening and filtering, we demonstrate a\ntemperature of 0.9$\\,\\pm\\,$0.1$\\,$mK, with scope for significant further\nimprovement. This platform is a key technological step, paving the way to\nobserving new quantum phenomena, and developing new generations of\nnanoelectronic devices exploiting correlated electron states.",
        "positive": "Laser-like Instabilities in Quantum Nano-electromechanical Systems: We discuss negative damping regimes in quantum nano-electromechanical systems\nformed by coupling a mechanical oscillator to a single-electron transistor\n(normal or superconducting). Using an analogy to a laser with a tunable\natom-field coupling, we demonstrate how these effects scale with system\nparameters. We also discuss the fluctuation physics of both the oscillator and\nthe single-electron transistor in this regime, and the degree to which the\noscillator motion is coherent."
    },
    {
        "anchor": "Vibrations of single-crystal gold nanorods and nanowires: The vibrations of gold nanowires and nanorods are investigated numerically in\nthe framework of continuum elasticity using the Rayleigh-Ritz variational\nmethod. Special attention is paid to identify the vibrations relevant in Raman\nscattering experiments. A comprehensive description of the vibrations of\nnanorods is proposed by determining their symmetry, comparing with standing\nwaves in the corresponding nanowires and estimating their Raman intensity. The\nrole of experimentally relevant parameters such as the anisotropic cubic\nlattice structure, the presence of faceted lateral surfaces and the shape of\nthe ends of the nanorods is evaluated. Elastic anisotropy is shown to play a\nsignificant role contrarily to the presence of facets. Localized vibrations are\nfound for nanorods with flat ends. Their evolution as the shape of the ends is\nchanged to half-spheres is discussed.",
        "positive": "Diffractive wave guiding of hot electrons by the Au (111) herringbone\n  reconstruction: The surface potential of the herringbone reconstruction on Au(111) is known\nto guide surface-state electrons along the potential channels. Surprisingly, we\nfind by scanning tunneling spectroscopy that hot electrons with kinetic\nenergies twenty times larger than the potential amplitude (38 meV) are still\nguided. The efficiency even increases with kinetic energy, which is reproduced\nby a tight binding calculation taking the known reconstruction potential and\nstrain into account. The guiding is explained by diffraction at the\ninhomogeneous electrostatic potential and strain distribution provided by the\nreconstruction."
    },
    {
        "anchor": "Hypersensitive tunable Josephson escape sensor for gigahertz astronomy: Sensitive photon detection in the gigahertz band constitutes the cornerstone\nto study different phenomena in astronomy, such as radio burst sources, galaxy\nformation, cosmic microwave background, axions, comets, gigahertz-peaked\nspectrum radio sources and supermassive black holes. Nowadays, state of the art\ndetectors for astrophysics are mainly based on transition edge sensors and\nkinetic inductance detectors. Overall, most sensible nanobolometers so far are\nsuperconducting detectors showing a noise equivalent power (NEP) as low as\n2x10-20 W/Hz1/2. Yet, fast thermometry at the nanoscale was demonstrated as\nwell with Josephson junctions through switching current measurements. In\ngeneral, detection performance are set by the fabrication process and limited\nby used materials. Here, we conceive and demonstrate an innovative tunable\nJosephson escape sensor (JES) based on the precise current control of the\ntemperature dependence of a fully superconducting one-dimensional nanowire\nJosephson junction. The JES might be at the core of future hypersensitive in\nsitu-tunable bolometers or single-photon detectors working in the gigahertz\nregime. Operated as a bolometer the JES points to a thermal fluctuation noise\n(TFN) NEP_TFN 1x10-25 W/Hz1/2, which as a calorimeter bounds the frequency\nresolution above 2 GHz, and resolving power below 40 at 50 GHz, as deduced from\nthe experimental data. Beyond the obvious applications in advanced ground-based\nand space telescopes for gigahertz astronomy, the JES might represent a\nbreakthrough in several fields of quantum technologies ranging from subTHz\ncommunications and quantum computing to cryptography and quantum key\ndistribution.",
        "positive": "Electron binding energy of donor in bilayer graphene with gate-tunable\n  gap: In gapped bilayer graphene, similarly to conventional semiconductors, Coulomb\nimpurities (such as nitrogen donors) may determine the activation energy of its\nconductivity and provide low temperature hopping conductivity. However, in\nspite of importance of Coulomb impurities, nothing is known about their\nelectron binding energy $E_b$ in the presence of gates. To close this gap, we\nstudy numerically the electron binding energy $E_b$ of a singly charged donor\nin BN-enveloped bilayer graphene with the top and bottom gates at distance $d$\nand gate-tunable gap $2\\Delta$. We show that for $10 < d < 200$ nm and $1 <\n\\Delta < 100$ meV the ratio $E_b/\\Delta$ changes from 0.4 to 1.5. The ratio\n$E_b/\\Delta$ stays close to unity because of the dominating role of the bilayer\npolarization screening which reduces the Coulomb potential well depth to values\n$\\sim \\Delta$. Still the ratio $E_b/\\Delta$ somewhat decreases with growing\n$\\Delta$, faster at small $\\Delta$ and slower at large $\\Delta$. On the other\nhand, $E_b/\\Delta$ weakly grows with $d$, again faster at small $\\Delta$ and\nslower at large $\\Delta$. We also studied the effect of trigonal warping and\nfound only a small reduction of $E_b/\\Delta$."
    },
    {
        "anchor": "Impurity effects on the resonant Andreev reflection in a finite-sized\n  carbon nanotube system: The influence of the impurity on the resonant Andreev reflection through a\nnormal-metal/carbon-nanotube/superconductor system is studied theoretically. It\nis found that the resonant Andreev reflection depends on the strength of the\nimpurity and the length of the armchair nanotube. The impurity which breaks the\nelectron-hole symmetry of the nanotubes greatly reduces the resonant Andreev\nreflection. The symmetry broken depends distinctly on the impurity strength.\nThe impurity effects on the Andreev reflection current at different bias are\nalso studied.",
        "positive": "Autoresonant control of the many-electron dynamics in nonparabolic\n  quantum wells: The optical response of nonparabolic quantum wells is dominated by a strong\npeak at the plasmon frequency. When the electrons reach the anharmonic regions,\nresonant absorption becomes inefficient. This limitation is overcome by using a\nchirped laser pulse in the autoresonant regime. By direct simulations using the\nWigner phase-space approach, the authors prove that, with a sequence of just a\nfew pulses, electrons can be efficiently detrapped from a nonparabolic well.\nFor an array of multiple quantum wells, they can create and control an\nelectronic current by suitably applying an autoresonant laser pulse and a\nslowly varying dc electric field."
    },
    {
        "anchor": "High sensitivity magnetic imaging using an array of spins in diamond: We present a solid state magnetic field imaging technique using a two\ndimensional array of spins in diamond. The magnetic sensing spin array is made\nof nitrogen-vacancy (NV) centers created at shallow depths. Their optical\nresponse is used for measuring external magnetic fields in close proximity.\nOptically detected magnetic resonance (ODMR) is readout from a 60x60 $\\mu$m\nfield of view in a multiplexed manner using a CCD camera. We experimentally\ndemonstrate full two-dimensional vector imaging of the magnetic field produced\nby a pair of current carrying micro-wires. The presented widefield NV\nmagnetometer offers in addition to its high magnetic sensitivity of 20\nnT/$\\sqrt{Hz}$ and vector reconstruction, an unprecedented spatio-temporal\nresolution and functionality at room temperature.",
        "positive": "Resistance due to vortex motion in the $\u03bd=1$ bilayer quantum Hall\n  superfluid: The longitudinal and Hall resistances have recently been measured for quantum\nHall bilayers at total filling $\\nu=1$ in the superfluid state with interlayer\npairing, both for currents flowing parallel to one another and for\n\"counterflowing\" currents in the two layers. Here I examine the contribution to\nthese resistances from the motion of unpaired vortices in these systems,\ndeveloping some possible explanations of various qualitative features of these\ndata."
    },
    {
        "anchor": "Properties of Quantum Hall Skyrmions from Anomalies: It is well known that the Fractional Quantum Hall Effect (FQHE) may be\neffectively represented by a Chern-Simons theory. In order to incorporate QH\nSkyrmions, we couple this theory to the topological spin current, and include\nthe Hopf term. The cancellation of anomalies for chiral edge states, and the\nproviso that Skyrmions may be created and destroyed at the edge, fixes the\ncoefficients of these new terms. Consequently, the charge and the spin of the\nSkyrmion are uniquely determined. For those two quantities we find the values\n$e\\nu N_{Sky}$ and $\\nu N_{Sky}/2$, respectively, where $e$ is electron charge,\n$\\nu$ is the filling fraction and $N_{Sky}$ is the Skyrmion winding number. We\nalso add terms to the action so that the classical spin fluctuations in the\nbulk satisfy the standard equations of a ferromagnet, with spin waves that\npropagate with the classical drift velocity of the electron.",
        "positive": "Fabrication of voltage gated spin Hall nano-oscillators: We demonstrate an optimized fabrication process for electric field (voltage\ngate) controlled nano-constriction spin Hall nano-oscillators (SHNOs),\nachieving feature sizes of <30 nm with easy to handle ma-N 2401 e-beam\nlithography negative tone resist. For the nanoscopic voltage gates, we utilize\na two-step tilted ion beam etching approach and through-hole encapsulation\nusing 30 nm HfO<sub>x</sub>. The optimized tilted etching process reduces\nsidewalls by 75% compared to no tilting. Moreover, the HfO<sub>x</sub>\nencapsulation avoids any sidewall shunting and improves gate breakdown. Our\nexperimental results on W/CoFeB/MgO/SiO<sub>2</sub> SHNOs show significant\nfrequency tunability (6 MHz/V) even for moderate perpendicular magnetic\nanisotropy. Circular patterns with diameter of 45 nm are achieved with an\naspect ratio better than 0.85 for 80% of the population. The optimized\nfabrication process allows incorporating a large number of individual gates to\ninterface to SHNO arrays for unconventional computing and densely packed\nspintronic neural networks."
    },
    {
        "anchor": "Topological Features of the Magnetic Response in Inhomogeneous Magnetic\n  Fields: We present topological features of the magnetic response (orbital and spin)\nof a two-dimensional degenerate and non interacting electron gas due to\ninhomogeneous applied magnetic fields. These issues are analysed from the point\nof view of the Index theory with a special emphasis on the non perturbative\naspects of this response. The limiting case of a Aharonov-Bohm magnetic flux\nline is studied in details and the results are extended to more general\nsituations.",
        "positive": "Observation of Dirac node formation and mass acquisition in a\n  topological crystalline insulator: In the recently discovered topological crystalline insulators (TCIs),\ntopology and crystal symmetry intertwine to create surface states with a unique\nset of characteristics. Among the theoretical predictions for TCIs is the\npossibility of imparting mass to the massless Dirac fermions by breaking\ncrystal symmetry, as well as a Lifshitz transition with a change of Fermi\nsurface topology. Here we report high resolution scanning tunneling microscopy\nstudies of a TCI, Pb1-xSnxSe. We demonstrate the formation of zero mass Dirac\nfermions protected by crystal symmetry and the mechanism of mass generation via\nsymmetry breaking, which constitute the defining characteristics of TCIs. In\naddition, we show two distinct regimes of fermiology separated by a Van-Hove\nsingularity at the Lifshitz transition point. Our work paves the way for\nengineering the Dirac band gap and realizing interaction-driven topological\nquantum phenomena in TCIs."
    },
    {
        "anchor": "Dirac fermion spectrum of the fractional quantum Hall states: Applying a unified approach, we study the integer quantum Hall effect (IQHE)\nand fractional quantum Hall effect (FQHE) in the Hofstadter model with short\nrange interactions between fermions. An effective field, that takes into\naccount the interaction between fermions, is determined by both amplitude and\nphase. Its amplitude is proportional to the interaction strength, the phase\ncorresponds to the minimum energy. In fact, the problem is reduced to the\nHarper equation with two different scales: the first is a magnetic scale with\nthe cell size corresponding to a unit quantum magnetic flux, the second scale\ndetermines the inhomogeneity of the effective field, forms the steady fine\nstructure of the Hofstadter spectrum and leads to the realization of fractional\nquantum Hall states. In a sample of finite size with open boundary conditions,\nthe fine structure of the Hofstadter spectrum consists of the Dirac branches of\nthe fermion excitations and includes the fine structure of the edge chiral\nmodes. The Chern numbers of the topological Hofstadter bands are conserved\nduring the formation of their fine structure. The edge modes are formed into\nthe Hofstadter bands. They connect the nearest-neighbor subbands and determine\nthe conductance for the fractional filling.",
        "positive": "Injection locking of multiple auto-oscillation modes in a tapered\n  nanowire spin Hall oscillator: Spin Hall oscillators (SHO) are promising candidates for the generation,\ndetection and amplification of high frequency signals, that are tunable through\na wide range of operating frequencies. They offer to be read out electrically,\nmagnetically and optically in combination with a simple bilayer design. Here,\nwe experimentally study the spatial dependence and spectral properties of\nauto-oscillations in SHO devices based on Pt(7 nm)/\\\nNi$_{\\mathrm{80}}$Fe$_{\\mathrm{20}}$(5 nm) tapered nanowires. Using Brillouin\nlight scattering microscopy, we observe two individual self-localized spin-wave\nbullets that oscillate at two distinct frequencies (5.2 GHz and 5.45 GHz) and\nare localized at different positions separated by about 750 nm within the SHO.\nThis state of a tapered SHO has been predicted by a Ginzburg-Landau\nauto-oscillator model, but not yet been directly confirmed experimentally. We\ndemonstrate that the observed bullets can be individually synchronized to\nexternal microwave signals, leading to a frequency entrainment, linewidth\nreduction and increase in oscillation amplitude for the bullet that is selected\nby the microwave frequency. At the same time, the amplitude of other parasitic\nmodes decreases, which promotes the single-mode operation of the SHO. Finally,\nthe synchronization of the spin-wave bullets is studied as a function of the\nmicrowave power. We believe that our findings promote the realization of\nextended spin Hall oscillators accomodating several distinct spin-wave bullets,\nthat jointly cover an extended range of tunability."
    },
    {
        "anchor": "Tunable THz Surface Plasmon Polariton based on Topological\n  Insulator-Layered Superconductor Hybrid Structure: We theoretically investigate the surface plasmon polariton (SPP) at the\ninterface between 3D strong topological insulator (TI) and layered\nsuperconductor-magnetic insulator structure. The tunability of SPP through\nelectronic doping can be enhanced when the magnetic permeability of the layered\nstructure becomes higher. When the interface is gapped by superconductivity or\nperpendicular magnetism, SPP dispersion is further distorted, accompanied by a\nshift of group velocity and penetration depth. Such a shift of SPP reaches\nmaximum when the magnitude of Fermi level approaches the gap value, and may\nlead to observable effects. The tunable SPP at the interface between layered\nsuperconductor and magnetism materials in proximity to TI surface may provide\nnew insight in the detection of Majorana Fermions.",
        "positive": "Topological quantum fluctuations and travelling wave amplifiers: It is now well-established that photonic systems can exhibit topological\nenergy bands; similar to their electronic counterparts, this leads to the\nformation of chiral edge modes which can be used to transmit light in a manner\nthat is protected against back-scattering. While it is understood how classical\nsignals can propagate under these conditions, it is an outstanding important\nquestion how the quantum vacuum fluctuations of the electromagnetic field get\nmodified in the presence of a topological band structure. We address this\nchallenge by exploring a setting where a non-zero topological invariant\nguarantees the presence of a parametrically-unstable chiral edge mode in a\nsystem with boundaries, even though there are no bulk-mode instabilities. We\nshow that one can exploit this to realize a topologically protected,\nquantum-limited travelling-wave parametric amplifier. The device is naturally\nprotected both against internal losses and back-scattering; the latter feature\nis in stark contrast to standard travelling wave amplifiers. This adds a new\nexample to the list of potential quantum devices that profit from topological\ntransport."
    },
    {
        "anchor": "Improved Single-Shot Qubit Readout Using Twin RF-SET Charge Correlations: High fidelity qubit readout is critical in order to obtain the thresholds\nneeded to implement quantum error correction protocols and achieve\nfault-tolerant quantum computing. Large-scale silicon qubit devices will have\ndensely-packed arrays of quantum dots with multiple charge sensors that are, on\naverage, farther away from the quantum dots, entailing a reduction in readout\nfidelities. Here, we present a readout technique that enhances the readout\nfidelity in a linear SiMOS 4-dot array by amplifying correlations between a\npair of single-electron transistors, known as a twin SET. By recording and\nsubsequently correlating the twin SET traces as we modulate the dot detuning\nacross a charge transition, we demonstrate a reduction in the charge readout\ninfidelity by over one order of magnitude compared to traditional readout\nmethods. We also study the spin-to-charge conversion errors introduced by the\nmodulation technique, and conclude that faster modulation frequencies avoid\nrelaxation-induced errors without introducing significant spin flip errors,\nfavouring the use of the technique at short integration times. This method not\nonly allows for faster and higher fidelity qubit measurements, but it also\nenhances the signal corresponding to charge transitions that take place farther\naway from the sensors, enabling a way to circumvent the reduction in readout\nfidelities in large arrays of qubits.",
        "positive": "Photon delocalization transition in dimensional crossover in layered\n  media: We report a crossover in optical propagation in random layered media from\nlocalization towards diffusion as the interaction of the wave with the sample\nis transformed from one to three-dimensional due to nonuniformity in the layer\nthickness. The crossover occurs at the point that the lateral spread of the\nwave equals the transverse coherence length in the transmitted speckle pattern."
    },
    {
        "anchor": "Cavity-photon induced high order transitions between ground states of\n  quantum dots: We show that quantum electromagnetic transitions to high orders are essential\nto describe the time-dependent path of a nanoscale electron system in a Coulomb\nblockage regime when coupled to external leads and placed in a\nthree-dimensional rectangular photon cavity. The electronic system consists of\ntwo quantum dots embedded asymmetrically in a short quantum wire. The two\nlowest in energy spin degenerate electron states are mostly localized in each\ndot with only a tiny probability in the other dot. In the presence of the leads\nwe identify a slow high order transition between the ground states of the two\nquantum dots. The Fourier power spectrum for photon-photon correlations in the\nsteady state shows a Fano-type of a resonance for the frequency of the slow\ntransition. Full account is taken of the geometry of the multi-level electronic\nsystem, and the electron-electron Coulomb interactions together with the para-\nand diamagnetic electron-photon interactions are treated with step wise exact\nnumerical diagonalization and truncation of appropriate many-body Fock spaces.\nThe matrix elements for all interactions are computed analytically or\nnumerically exactly.",
        "positive": "Charge Transport Transitions and Scaling in Disordered Arrays of\n  Metallic Dots: We examine the charge transport through disordered arrays of metallic dots\nusing numerical simulations. We find power law scaling in the current-voltage\ncurves for arrays containing no voids, while for void-filled arrays charge\nbottlenecks form and a single scaling is absent, in agreement with recent\nexperiments. In the void-free case we also show that the scaling exponent\ndepends on the effective dimensionality of the system. For increasing applied\ndrives we find a transition from 2D disordered filamentary flow near threshold\nto a 1D smectic flow which can be identified experimentally using\ncharacteristics in the transport curves and conduction noise."
    },
    {
        "anchor": "Two-photon Induced Hot Electron Transfer to a Single Molecule in a\n  Scanning Tunneling Microscope: The junction of a scanning tunneling microscope (STM) operating in the\ntunneling regime was irradiated with femtosecond laser pulses. A photo-excited\nhot electron in the STM tip resonantly tunnels into an excited state of a\nsingle molecule on the surface, converting it from the neutral to the anion.\nThe electron transfer rate depends quadratically on the incident laser power,\nsuggesting a two-photon excitation process. This nonlinear optical process is\nfurther confirmed by the polarization measurement. Spatial dependence of the\nelectron transfer rate exhibits atomic-scale variations. A two-pulse\ncorrelation experiment reveals the ultrafast dynamic nature of photo-induced\ncharging process in the STM junction. Results from these experiments are\nimportant for understanding photo-induced interfacial charge transfer in many\nnanoscale inorganic-organic structures.",
        "positive": "Observing imperfection in atomic interfaces for van der Waals\n  heterostructures: Vertically stacked van der Waals heterostructures are a lucrative platform\nfor exploring the rich electronic and optoelectronic phenomena in\ntwo-dimensional materials. Their performance will be strongly affected by\nimpurities and defects at the interfaces. Here we present the first systematic\nstudy of interfaces in van der Waals heterostructure using cross sectional\nscanning transmission electron microscope (STEM) imaging. By measuring\ninterlayer separations and comparing these to density functional theory (DFT)\ncalculations we find that pristine interfaces exist between hBN and MoS2 or WS2\nfor stacks prepared by mechanical exfoliation in air. However, for two\ntechnologically important transition metal dichalcogenide (TMDC) systems, MoSe2\nand WSe2, our measurement of interlayer separations provide the first evidence\nfor impurity species being trapped at buried interfaces with hBN: interfaces\nwhich are flat at the nanometer length scale. While decreasing the thickness of\nencapsulated WSe2 from bulk to monolayer we see a systematic increase in the\ninterlayer separation. We attribute these differences to the thinnest TMDC\nflakes being flexible and hence able to deform mechanically around a sparse\npopulation of protruding interfacial impurities. We show that the air sensitive\ntwo dimensional (2D) crystal NbSe2 can be fabricated into heterostructures with\npristine interfaces by processing in an inert-gas environment. Finally we find\nthat adopting glove-box transfer significantly improves the quality of\ninterfaces for WSe2 compared to processing in air."
    },
    {
        "anchor": "Ferromagnetism and spin-dependent transport at a complex oxide interface: Complex oxide interfaces are a promising platform for studying a wide array\nof correlated electron phenomena in low-dimensions, including magnetism and\nsuperconductivity. The microscopic origin of these phenomena in complex oxide\ninterfaces remains an open question. Here we investigate for the first time the\nmagnetic properties of semi-insulating NdTiO$_3$/SrTiO$_3$ (NTO/STO) interfaces\nand present the first milli-Kelvin study of NTO/STO. The magnetoresistance (MR)\nreveals signatures of local ferromagnetic order and of spin-dependent\nthermally-activated transport, which are described quantitatively by a simple\nphenomenological model. We discuss possible origins of the interfacial\nferromagnetism. In addition, the MR also shows transient hysteretic features on\na timescale of ~10-100 seconds. We demonstrate that these are consistent with\nan extrinsic magneto-thermal origin, which may have been misinterpreted in\nprevious reports of magnetism in STO-based oxide interfaces. The existence of\nthese two MR regimes (steady-state and transient) highlights the importance of\ntime-dependent measurements for distinguishing signatures of ferromagnetism\nfrom other effects that can produce hysteresis at low temperatures.",
        "positive": "Spin superconductor in ferromagnetic graphene: We show a spin superconductor (SSC) in ferromagnetic graphene as the\ncounterpart to the charge superconductor, in which a spin-polarized\nelectron-hole pair plays the role of the spin $2 (\\hbar/2)$ `Cooper pair' with\na neutral charge. We present a BCS-type theory for the SSC. With the\n`London-type equations' of the super-spin-current density, we show the\nexistence of an electric `Meissner effect' against a spatial varying electric\nfield. We further study a SSC/normal conductor/SSC junction and predict a\nspin-current Josephson effect."
    },
    {
        "anchor": "Fully suspended nano-beams for quantum fluids: Non-invasive probes are keystones of fundamental research. Their size, and\nmaneuverability (in terms of e.g. speed, dissipated power) define their\napplicability range for a specific use. As such, solid state physics possesses\ne.g. Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), or\nScanning SQUID Microscopy. In comparison, quantum fluids (superfluid $^3$He,\n$^4$He) are still lacking probes able to sense them (in a fully controllable\nmanner) down to their smallest relevant lengthscales, namely the coherence\nlength $\\xi_0$. In this work we report on the fabrication and cryogenic\ncharacterization of fully suspended (hanging over an open window, with no\nsubstrate underneath) Si$_3$N$_4$ nano-beams, of width down to 50 nm and\nquality factor up to $10^5$. As a benchmark experiment we used them to\ninvestigate the Knudsen boundary layer of a rarefied gas: $^4$He at very low\npressures. The absence of the rarefaction effect due to the nearby chip surface\ndiscussed in Gazizulin et al. [1] is attested, while we report on the effect of\nthe probe size itself.",
        "positive": "Transport signatures of top-gate bound states with strong Rashba-Zeeman\n  effect: We suggest a single-mode spin injection scheme in non-ferromagnetic quantum\nchannels utilizing perpendicular strong Rashba spin-orbit and Zeeman fields. By\napplying a positive top-gate potential in order to inject electrons from the\nspin-orbit gap to the low-energy regime, we observe coherent destruction of\ntransport signatures of a hole-like quasi-bound state, an electron-like\nquasi-bound state, or a hole-like bound state features that are sensitive to\nthe selection of the top-gate length along the transport direction."
    },
    {
        "anchor": "Robust high-temperature topological excitonic insulator of\n  transition-metal carbides (MXenes): Topological excitonic insulators combine topological edge states and\nspontaneous exciton condensation, with dual functionality of topological\ninsulators and excitonic insulators. Yet, they are very rare and little is\nknown about their formation. In this work, we find that a mechanism dubbed as\nparity frustration prevents excitonic instability in usual topological\ninsulators, and those whose band inversion is independent of spin-orbit\ncoupling are possible candidates. We verify this by first-principles\ncalculations on monolayer transition-metal carbides (MXenes), which show a\nrobust thermal-equilibrium exciton condensation, being sufficient for\ntopological applications at room temperature. Such a state can be identified by\nangle-resolved photoemission spectroscopy and transport measurement. Our work\nprovides not only a guide for finding more topological excitonic insulators,\nbut also a new platform for studying the interplay between non-trivial band\ntopology and quantum many-body effects.",
        "positive": "Quantum interference through gated single-molecule junctions: We discuss the general form of the transmission spectrum through a molec-\nular junction in terms of the Green function of the isolated molecule. By\nintroducing a tight binding method, we are able to translate the Green func-\ntion properties into practical graphical rules for assessing beforehand the\npossible existence of antiresonances in an energy range for a given choice of\nconnecting sites. The analysis is exemplified with a benzene molecule under a\nhypothetical local gate, which allows one to continuously tune the on-site\nenergy of single atoms, for various connection topologies and gate positions."
    },
    {
        "anchor": "Semiclassical magnetotransport including the effects of the Berry\n  curvature and Lorentz force: In topological semimetals and insulators, negative longitudinal\nmagnetoresistance and angle-dependent planar Hall effect have been reported\narising from the Berry curvature. Using the Boltzmann transport theory, we\npresent a closed-form expression for the nonequilibrium distribution function\nwhich includes both the effects of the Berry curvature and Lorentz force. Using\nthis formulation, we obtain analytical expressions for conductivity and\nresistivity tensors in Weyl semimetals demonstrating a non-monotonic field\ndependence arising from the competition between the two effects.",
        "positive": "Four-dimensional semimetals with tensor monopoles: From surface states\n  to topological responses: Quantum anomalies offer a useful guide for the exploration of transport\nphenomena in topological semimetals. In this work, we introduce a model\ndescribing a semimetal in four spatial dimensions, whose nodal points act like\ntensor monopoles in momentum space. This system is shown to exhibit\nmonopole-to-monopole phase transitions, as signaled by a change in the value of\nthe topological Dixmier-Douady invariant as well as by the associated surface\nstates on its boundary. We use this model to reveal an intriguing \"4D parity\nmagnetic effect\", which stems from a parity-type anomaly. In this effect,\ntopological currents are induced upon time-modulating the separation between\nthe fictitious monopoles in the presence of a magnetic perturbation. Besides\nits theoretical implications in both condensed matter and quantum field theory,\nthe peculiar 4D magnetic effect revealed by our model could be measured by\nsimulating higher-dimensional semimetals in synthetic matter."
    },
    {
        "anchor": "Scattering of massless Dirac fermions in circular p-n junctions with and\n  without magnetic field: In the absence of a magnetic field, scattered wavefunction inside a circular\np-n junction in graphene exhibits an interference pattern with high intensity\nmaximum located around the caustics. We investigate the wavefunctions in the\npresence of a uniform magnetic field outside the circular region to show how\nthe loci of the high intensity region changes by forming Landau level structure\noutside the circular region and a central high intensity region inside the\ncircular p-n junction due to the strong reflection of massless Dirac fermions\nby the outside magnetic field. We conclude by suggesting experimental ways to\ndetect such change of pattern due to the effect of the magnetic field.",
        "positive": "Matrix product state simulations of quantum quenches and transport in\n  Coulomb blockaded superconducting devices: Superconducting devices subject to strong charging energy interactions and\nCoulomb blockade are one of the key elements for the development of\nnanoelectronics and constitute common building blocks of quantum computation\nplatforms and topological superconducting setups. The study of their transport\nproperties is non-trivial and some of their non-perturbative aspects are hard\nto capture with the most ordinary techniques. Here we present a matrix product\nstate approach to simulate the real-time dynamics of these systems. We propose\na study of their transport based on the analysis of the currents after quantum\nquenches connecting such devices with external leads. Our method is based on\nthe combination of a Wilson chain construction for the leads and a mean-field\nBCS description for the superconducting scatterers. In particular, we employ a\nquasiparticle energy eigenbasis which greatly reduces their entanglement growth\nand we introduce an auxiliary degree of freedom to encode the device total\ncharge. This approach allows us to treat non-perturbatively both their charging\nenergy and coupling with external electrodes. We show that our construction is\nable to describe the Coulomb diamond structure of a superconducting dot with\nsubgap states, including its sequential tunneling and cotunneling features. We\nalso study the conductance zero-bias peaks caused by Majorana modes in a\nblockaded Kitaev chain, and compare our results with common Breit-Wigner\npredictions."
    },
    {
        "anchor": "Substitutional mechanism for growth of hexagonal boron nitride on\n  epitaxial graphene: Monolayer-thick hexagonal boron nitride (h-BN) is grown on graphene on\nSiC(0001), by exposure of the graphene to borazine, (BH)3(NH)3, at 1100 C. The\nh-BN films form ~2-micrometer size grains with a preferred orientation of 30\ndegrees relative to the surface graphene. Low-energy electron microscopy is\nemployed to provide definitive signatures of the number and composition of\ntwo-dimensional (2D) planes across the surface. These grains are found to form\nby substitution for the surface graphene, with the C atoms produced by this\nsubstitution then being incorporated below the h-BN (at the interface between\nthe existing graphene and the SiC) to form a new graphene plane.",
        "positive": "Quantum analogue of the spin-flop transition for a spin pair: Quantum (step-like) magnetization curves are studies for a spin pair with\nantiferromagnetic coupling in the presence of a magnetic field parallel to the\neasy axis of the magnetic anisotropy. The consideration is done both\nanalytically and numerically for a wide range of the anisotropy constants and\nspins up to $S \\gtrsim 100$. Depending on the origin of the anisotropy\n(exchange or single-ion), the magnetization curve can demonstrate the jumps\nmore than unity and the concentration of the unit jumps in a narrow range of\nthe field. We also point the region of the problem parameters, where the\nbehavior is quasiclassical for $S = 5$, and where system is substantially\nquantum in the limit $S \\to \\infty$."
    },
    {
        "anchor": "Theory of plasmon-enhanced metal photoluminescence: Metal photoluminescence (MPL) originates from radiative recombination of\nphotoexcited core holes and conduction band electrons. In metal nanostructures,\nMPL is enhanced due to the surface plasmon local field effect. We identify\nanother essential process in plasmon-assisted MPL - excitation of Auger\nplasmons by core holes - that hinders MPL from small nanostructures. We develop\na microscopic theory of plasmon-enhanced MPL that incorporates both\nplasmon-assisted enhancement and suppression mechanisms and derive the\nenhancement factor for MPL quantum efficiency. Our numerical calculations of\nMPL from Au nanoparticles are in excellent agreement with the experiment.",
        "positive": "Nonlinear response of a MgZnO/ZnO heterostructure close to zero bias: We report on magnetotransport properties of a MgZnO/ZnO heterostructure\nsubjected to weak direct currents. We find that in the regime of overlapping\nLandau levels, the differential resistivity acquires a quantum correction\nproportional to both the square of the current and the Dingle factor. The\nanalysis shows that the correction to the differential resistivity is dominated\nby a current-induced modification of the electron distribution function and\nallows us to access both quantum and inelastic scattering rates."
    },
    {
        "anchor": "Dissipation-free modes in dissipative systems: The coupling between a system and its environment (or bath) always leads to\ndissipation. We show, however, that a system composed of two subsystems can\nhave a dissipation-free mode, if the bath is shared between the two subsystems.\nReading in reverse, a shared bath does not contribute to the dissipation of all\nmodes. As a key example, we consider a simple model for a two-sublattice\nantiferromagnet, where the environment is modeled by a bath that is shared\nbetween the two sublattice magnetizations. In our model, we find that the\nN\\'eel order parameter is a dissipation-free mode. For antiferromagnets, our\nresults offer an explanation for why the dissipation rate of the N\\'eel vector\nis typically much lower than that of the average magnetization. In general, our\nresults suggest a way to reduce dissipation (and decoherence) for some modes in\ncomposite systems, which could have experimental and technological\napplications.",
        "positive": "Probing spin entanglement by gate-voltage-controlled interference of\n  current correlation in quantum spin Hall insulators: We propose an entanglement detector composed of two quantum spin Hall\ninsulators and a side gate deposited on one of the edge channels. For an ac\ngate voltage, the differential noise contributed from the entangled electron\npairs exhibits the nontrivial step structures, from which the spin entanglement\nconcurrence can be easily obtained. The possible spin dephasing effects in the\nquantum spin Hall insulators are also included."
    },
    {
        "anchor": "Superradiance of a 2D-spaser array: We demonstrate that interacting spasers arranged in a 2D array of arbitrary\nsize can be mutually synchronized allowing them to supperradiate. For arrays\nsmaller than the free space wavelength, the total radiated power is\nproportional to the square of the number N of spasers. For larger arrays, the\nradiation power is linear in N. However, the emitted beam becomes highly\ndirectional with intensity of radiation proportional to N^2 in the direction\nperpendicular to the plane of the array. Thus, spasers, which mainly amplify\nnear fields, become an efficient source of far field radiation when they are\narranged into an array.",
        "positive": "Microwave Rectification at the Boundary between Two-Dimensional Electron\n  Systems: Rectification of microwave radiation (20-40 GHz) by a line boundary between\ntwo two-dimensional metals on a silicon surface was observed and investigated\nat different temperatures, in-plane magnetic fields and microwave powers. The\nrectified voltage $V_{dc}$ is generated whenever the electron densities\n$n_{1,2}$ of the two metals are different, changing polarity at $n_1 \\approx\nn_2$. Very strong nonlinear response is found when one of the two 2D metals is\nclose to the electron density corresponding to the reported magnetic\ninstability in this system."
    },
    {
        "anchor": "Theoretical Description of Scanning Tunneling Potentiometry: A theoretical description of scanning tunneling potentoimetry (STP)\nmeasurement is presented to address the increasing need for a basis to\ninterpret experiments on macrscopic samples. Based on a heuristic understanding\nof STP provided to facilitate theoretical understanding, the total tunneling\ncurrent related to the density matrix of the sample is derived within the\ngeneral framework of quantum transport. The measured potentiometric voltage is\ndetermined implicitly as the voltage necessary to null the tunneling current.\nExplicit expressions of measured voltages are presented under certain\nassumptions, and limiting cases are discussed to connect to previous results.\nThe need to go forward and formulate the theory in terms of a local density\nmatrix is also discussed.",
        "positive": "Dynamics of macrospin under periodic field and spin transfer torque: The dynamics of a macrospin model for a single magnetic domain is\ninvestigated in two cases: (i) under the action of a periodic magnetic field\nand (ii) under the external field plus a spin transfer torque from\nspin-polarized current or spin current. It has been proved that (i) without\nspin transfer torque, the trajectory of magnetization (hysteresis) is always a\nclosed curve oscillating between two stable points and following the same path\neach time; (ii) under the action of a constant field (or with small periodic\nperturbation) and a constant spin transfer torque, the spin would always turn\nto the stable solution finally, which is independent of the parameters or\ninitial conditions; (iii) considering a periodic oscillating field plus a spin\ntransfer torque, the system can also have a stable solution around a limit\ncircle, but on some special points on the attractor, the system may be\nsensitive to the initial conditions and have no limit circle."
    },
    {
        "anchor": "Semiconductor quantum ring as a solid-state spin qubit: The implementation of a spin qubit in a quantum ring occupied by one or a few\nelectrons is proposed. Quantum bit involves the Zeeman sublevels of the highest\noccupied orbital. Such a qubit can be initialized, addressed, manipulated, read\nout and coherently coupled to other quantum rings. An extensive discussion of\nrelaxation and decoherence is presented. By analogy with quantum dots, the spin\nrelaxation times due to spin-orbit interaction for experimentally accessible\nquantum ring architectures are calculated. The conditions are formulated under\nwhich qubits build on quantum rings can have long relaxation times of the order\nof seconds. Rapidly improving nanofabrication technology have made such ring\ndevices experimentally feasible and thus promising for quantum state\nengineering.",
        "positive": "Impurity-induced vector spin chirality and anomalous Hall effect in\n  ferromagnetic metals: Scattering by multiple scatterers sometimes gives rise to nontrivial\nconsequences such as anomalous Hall effect. We here study a mechanism for\nanomalous Hall effect which originates from the correlation of nonmagnetic\nimpurities and localized moments; a Hall effect induced by vector spin\nchirality. Using a scattering theory approach, we study the skew scattering\ninduced by the scattering processes that involve two magnetic moments and a\nnon-magnetic impurity, which is proportional to the vector spin chirality of\nthe spins in the vicinity of the non-magnetic impurity. Furthermore, we show\nthat a finite vector spin chirality naturally exists around an impurity in the\nusual ferromagnetic metals at finite temperature due to the local\ninversion-symmetry breaking by the impurity. The result is potentially relevant\nto magnetic oxides which the anomalous Hall effect is enhanced at finite\ntemperatures."
    },
    {
        "anchor": "Analog of the Auger effect in radiative decay of a trion in a quantum\n  well: We have analyzed the energetics of decay of the X^- trion (exciton +\nelectron) on the assumption that the exciton and trion are independent\nexcitations of a single two-dimensional semiconducting quantum well. For the\nfirst time, it has been shown that in filling a well with electrons from a\nselective donor-doped matrix, the binding energy of the trion (of the electron\nwith the exciton) increases linearly with a shift of the Fermi level into the\ndepth of the c band. This agrees with the well-known experimental data on the\nlow-temperature radiative decay (photoluminescence) of trions in the\nheterostructures ZnSe/Zn_0.89Mg_0.11S_0.18Se_0.82 and CdTe/Cd_0.7Mg_0.3Te.",
        "positive": "Single charge sensing and transport in double quantum dots fabricated\n  from commercially grown Si/SiGe heterostructures: We perform quantum Hall measurements on three types of commercially available\nmodulation doped Si/SiGe heterostructures to determine their suitability for\ndepletion gate defined quantum dot devices. By adjusting the growth parameters,\nwe are able to achieve electron gases with charge densities 1-3 X 10^{11}/cm^2\nand mobilities in excess of 100,000 cm^2/Vs. Double quantum dot devices\nfabricated on these heterostructures show clear evidence of single charge\ntransitions as measured in dc transport and charge sensing and exhibit electron\ntemperatures of 100 mK in the single quantum dot regime."
    },
    {
        "anchor": "Adsorption properties of a nitrogen atom on the anionic golden fullerene\n  Au$_{16}^{-}$: Using density functional theory, we examine a nitrogen-doped anionic golden\ncage (NAu$_{16}^-$). For the exohedral adsorption that is more stable than the\nendohedral doping, the bridge and hollow sites have larger binding energies\nthan the atop sites by ~1 eV. When the N atom is adsorbed on the cage,\nelectrons are transferred from Au$_{16}^-$ to the N atom. The transition\nbetween the exohedral and endohedral adsorption may occur thermally through a\nbridge site. In the infrared active vibrational spectra, exohedral doping\ncauses greater intensities at higher frequencies than endohedral doping.",
        "positive": "Optical Rectification and Thermal Currents in Optical Tunneling Gap\n  Antennas: Electrically-contacted optical gap antennas are nanoscale interface devices\nenabling the transduction between photons and electrons. This new generation of\ndevices captures visible to near infrared electromagnetic radiation and\nconverts the incident energy in a direct-current (DC) electrical signal. The\nnanoscale rectenna is usually constituted of metal elements (e.g. gold). Light\nabsorption by the metal contacts may lead to additional thermal effects which\nneed to be taken into account to understand the complete photo- response of the\ndevice. The purpose of this communication is to discuss the contribution of\nlaser-induced thermo-electric effects in the photo-assisted electronic\ntransport."
    },
    {
        "anchor": "Thermoelectric and optical probes for a Fermi surface topology change in\n  noncentrosymmetric metals: Noncentrosymmetric metals such as Li$_2$(Pd$_{1-x}$Pt$_x$)$_3$B have\ndifferent Fermi surface topology below and above the band touching point where\nspin-degeneracy is not lifted by the spin-orbit coupling. We investigate\nthermoelectric and optical response as probes for this Fermi surface topology\nchange. We show that the chemical potential displays a dimensional crossover\nfrom a three-dimensional to one-dimensional characteristics as the descending\nFermi energy crosses the band touching point. This dimensional crossover is due\nto the existence of different Fermi surface topology above and below the band\ntouching point. We obtain an exact expression of relaxation time due to\nshort-range scatterer by solving Boltzmann transport equations\nself-consistently. The thermoelctric power and figure of merit are\nsignificantly enhanced as the Fermi energy goes below the band touching point\nowing to the underlying one-dimensional-like nature of noncentrosymmteric bulk\nmetals. The value of thermoelectric figure of merit goes beyond two as the\nFermi energy approaches to the van Hove singularity for lower spin-orbit\ncoupling. Similarly, the studies of the zero-frequency and finite-frequency\noptical conductivities in the zero-momentum limit reflect the nature of\ntopological change of the Fermi surface. The Hall coefficient and optical\nabsorption width exhibit distinct signatures in response to the changes in\nFermi surface topology.",
        "positive": "Magnetic Tunnel Junction Performance Under Mechanical Strain: In this work we investigate the effect of the mechanical stress on the\nperformance of magnetic tunnel junctions (MTJ) with perpendicular magnetic\nanisotropy. We developed a 4-point bending setup, that allows us to apply a\nconstant stress over a large substrate area with access to electrical\nmeasurements and external magnetic field. This setup enables us to measure key\ndevice performance parameters, such as tunnel magnetoresistance (TMR),\nswitching current ($I_c^{50\\%}$) and thermal stability ($\\Delta$), as a\nfunction of applied stress. We find that variations in these parameters are\nnegligible: less than $\\SI{2}{\\percent}$ over the entire measured range between\nthe zero stress condition and the maximum stress at the point of wafer\nbreakage."
    },
    {
        "anchor": "Visualizing near-coexistence of massless Dirac electrons and\n  ultra-massive saddle point electrons: Strong singularities in the electronic density of states amplify correlation\neffects and play a key role in determining the ordering instabilities in\nvarious materials. Recently high order van Hove singularities (VHSs) with\ndiverging power-law scaling have been classified in single-band electron\nmodels. We show that the 110 surface of Bismuth exhibits high order VHS with an\nusually high density of states divergence $\\sim (E)^{-0.7}$. Detailed mapping\nof the surface band structure using scanning tunneling microscopy and\nspectroscopy combined with first-principles calculations show that this\nsingularity occurs in close proximity to Dirac bands located at the center of\nthe surface Brillouin zone. The enhanced power-law divergence is shown to\noriginate from the anisotropic flattening of the Dirac band just above the\nDirac node. Such near-coexistence of massless Dirac electrons and ultra-massive\nsaddle points enables to study the interplay of high order VHS and Dirac\nfermions.",
        "positive": "Velocity weakening and possibility of aftershocks in nanofriction\n  experiments: We study the frictional behavior of small contacts as those realized in the\natomic force microscope and other experimental setups, in the framework of\ngeneralized Prandtl-Tomlinson models. Particular attention is paid to\nmechanisms that generate velocity weakening, namely a decreasing average\nfriction force with the relative sliding velocity.The mechanisms studied model\nthe possibility of viscous relaxation, or aging effects in the contact. It is\nfound that, in addition to producing velocity weakening, these mechanisms can\nalso produce aftershocks at sufficiently low sliding velocities. This provides\na remarkable analogy at the microscale, of friction properties at the\nmacroscale, where aftershocks and velocity weakening are two fundamental\nfeatures of seismic phenomena."
    },
    {
        "anchor": "Phonon-assisted relaxation between hole states in quantum dot molecules: We study theoretically phonon-assisted relaxation and inelastic tunneling of\nholes in a double quantum dot. We derive hole states and relaxation rates from\nkp Hamiltonians and show that there is a finite distance between the dots where\nlifetimes of hole states are very long which is related to vanishing tunnel\ncoupling. We show also that the light hole admixture to hole states can\nconsiderably affect the hole relaxation rates even though its magnitude is very\nsmall.",
        "positive": "Adiabatic pumping through a quantum dot with coulomb interactions: A\n  perturbation expansion in the tunnel coupling: We present a diagrammatic real-time approach to adiabatic pumping of\nelectrons through interacting quantum dots. Performing a systematic\nperturbation expansion in the tunnel-coupling strength, we compute the charge\npumped through a single-level quantum dot per pumping cycle. The combination of\nCoulomb interaction and quantum fluctuations, accounted for in contributions of\nhigher order in the tunnel coupling, modifies the pumping characteristics via\nan interaction-dependent renormalization of the quantum-dot level. The latter\nis even responsible for the {\\em dominant} contribution to the pumped charge\nwhen pumping via time-dependent tunnel-coupling strengths."
    },
    {
        "anchor": "Particle-Hole Symmetry and the Fractional Quantum Hall Effect in the\n  Lowest Landau Level: We report on detailed experimental studies of a high-quality heterojunction\ninsulated-gate field-effect transistor (HIGFET) to probe the particle-hole\nsymmetry (PHS) of the FQHE states about half-filling in the lowest Landau\nlevel. The HIGFET was specially designed to vary the density of a\ntwo-dimensional electronic system under constant magnetic fields. We find in\nour constant magnetic field, variable density measurements that the sequence of\nFQHE states at filling factors nu = 1/3, 2/5, 3/7 ... and its particle-hole\nconjugate states at filling factors 1 - nu = 2/3, 3/5, 4/7 ... have a very\nsimilar energy gap. Moreover, a reflection symmetry can be established in the\nmagnetoconductivities between the nu and 1 - nu states about half-filling. Our\nresults demonstrate that the FQHE states in the lowest Landau level are\nmanifestly particle-hole symmetric.",
        "positive": "Zero-Energy State Localized near an Arbitrary Edge in Quadrupole\n  Topological Insulators: A two-dimensional quadrupole topological insulator on a square lattice is a\ntypical example of a higher-order topological insulator. It hosts an edge state\nlocalized near each of its $90^{\\circ}$ corners at an energy $E$ inside the\nband gap, where $E$ is set equal to zero for simplicity. Although the\nappearance of an edge state has been shown in simple systems with only\n$90^{\\circ}$ corners, it is uncertain whether a similar localized state can\nappear at $E = 0$ near a complicated edge consisting of multiple $90^{\\circ}$\nand $270^{\\circ}$ corners. Here, we present a numerical method to determine the\nwavefunction of a zero-energy state localized near an arbitrary edge. This\nmethod enables us to show that one localized state appears at $E = 0$ if the\nedge consists of an odd number of corners. In contrast, the energy of localized\nstates inevitably deviates from $E = 0$ if the edge includes an even number of\ncorners."
    },
    {
        "anchor": "Van der Waals Multiferroic Tunnel Junctions: Multiferroic tunnel junctions (MFTJs) have aroused significant interest due\nto their functional properties useful for non-volatile memory devices. So far,\nhowever, all the existing MFTJs have been based on perovskite-oxide\nheterostructures limited by a relatively high resistance-area (RA) product\nunfavorable for practical applications. Here, using first-principles\ncalculations, we explore spin-dependent transport properties of van der Waals\n(vdW) MFTJs which consist of two-dimensional (2D) ferromagnetic FenGeTe2 (n =\n3, 4, 5) electrodes and 2D ferroelectric In2Se3 barrier layers. We demonstrate\nthat such FemGeTe2/In2Se3/FenGeTe2 (m, n = 3, 4, 5) MFTJs exhibit multiple\nnon-volatile resistance states associated with different polarization\norientation of the ferroelectric In2Se3 layer and magnetization alignment of\nthe two ferromagnetic FenGeTe2 layers. We find a remarkably low RA product\nwhich makes the proposed vdW MFTJs superior to the conventional MFTJs in terms\nof their promise for non-volatile memory applications.",
        "positive": "Nanosecond Optically Induced Phase Transformation in Compressively\n  Strained BiFeO3 on LaAlO3: Above-bandgap optical illumination induces a transformation from tilted\ntetragonal-like (T-like) and rhombohedral-like (R-like) phases to an untilted\nT-like phase in compressively strained BiFeO3. Optical excitation leads to an\nout-of-plane lattice expansion in the T-like phase. The transformation proceeds\nin regions with boundaries between the T-like and tilted R-like and tilted\nT-like phases, consistent with the motion of a boundary. The optically induced\ntransformation indicates that there are new optically driven routes towards\nnanosecond-scale control of phase transformations in ferroelectrics and\nmultiferroics."
    },
    {
        "anchor": "Multi-Lattice Kinetic Monte Carlo Simulations from First-Principles:\n  Reduction of the Pd(100) Surface Oxide by CO: We present a multi-lattice kinetic Monte Carlo (kMC) approach that\nefficiently describes the atomistic dynamics of morphological transitions\nbetween commensurate structures at crystal surfaces. As an example we study the\nreduction of a $(\\sqrt{5}\\times \\sqrt{5})R27^{\\circ}$ PdO(101) overlayer on\nPd(100) in a CO atmosphere. Extensive density-functional theory calculations\nare used to establish an atomistic pathway for the oxide reduction process.\nFirst-principles multi-lattice kMC simulations on the basis of this pathway\nfully reproduce the experimental temperature dependence of the reduction rate\n[Fernandes et al., Surf. Sci. 2014, 621, 31-39] and highlight the crucial role\nof elementary processes special to the boundary between oxide and metal\ndomains.",
        "positive": "Paired states of fermions in two dimensions with breaking of parity and\n  time-reversal symmetries, and the fractional quantum Hall effect: We analyze pairing of fermions in two dimensions for fully-gapped cases with\nbroken parity (P) and time-reversal (T), especially cases in which the gap\nfunction is an orbital angular momentum ($l$) eigenstate, in particular $l=-1$\n(p-wave, spinless or spin-triplet) and $l=-2$ (d-wave, spin-singlet). For\n$l\\neq0$, these fall into two phases, weak and strong pairing, which may be\ndistinguished topologically. In the cases with conserved spin, we derive\nexplicitly the Hall conductivity for spin as the corresponding topological\ninvariant. For the spinless p-wave case, the weak-pairing phase has a pair\nwavefunction that is asympototically the same as that in the Moore-Read\n(Pfaffian) quantum Hall state, and we argue that its other properties (edge\nstates, quasihole and toroidal ground states) are also the same, indicating\nthat nonabelian statistics is a {\\em generic} property of such a paired phase.\nThe strong-pairing phase is an abelian state, and the transition between the\ntwo phases involves a bulk Majorana fermion, the mass of which changes sign at\nthe transition. For the d-wave case, we argue that the Haldane-Rezayi state is\nnot the generic behavior of a phase but describes the asymptotics at the\ncritical point between weak and strong pairing, and has gapless fermion\nexcitations in the bulk. In this case the weak-pairing phase is an abelian\nphase which has been considered previously. In the p-wave case with an unbroken\nU(1) symmetry, which can be applied to the double layer quantum Hall problem,\nthe weak-pairing phase has the properties of the 331 state, and with nonzero\ntunneling there is a transition to the Moore-Read phase. The effects of\ndisorder on noninteracting quasiparticles are considered."
    },
    {
        "anchor": "Fragility of spectral flow for topological phases in non-Wigner-Dyson\n  classes: Topological insulators and superconductors support extended surface states\nprotected against the otherwise localizing effects of static disorder.\nSpecifically, in the Wigner-Dyson insulators belonging to the symmetry classes\nA, AI, and AII, a band of extended surface states is continuously connected to\na likewise extended set of bulk states forming a ``bridge'' between different\nsurfaces via the mechanism of spectral flow. In this work we show that this\nprinciple becomes \\emph{fragile} in the majority of non-Wigner-Dyson\ntopological superconductors and chiral topological insulators. In these\nsystems, there is precisely one point with granted extended states, the center\nof the band, $E=0$. Away from it, states are spatially localized, or can be\nmade so by the addition of spatially local potentials. Considering the\nthree-dimensional insulator in class AIII and winding number $\\nu=1$ as a\nparadigmatic case study, we discuss the physical principles behind this\nphenomenon, and its methodological and applied consequences. In particular, we\nshow that low-energy Dirac approximations in the description of surface states\ncan be treacherous in that they tend to conceal the localizability phenomenon.\nWe also identify markers defined in terms of Berry curvature as measures for\nthe degree of state localization in lattice models, and back our analytical\npredictions by extensive numerical simulations. A main conclusion of this work\nis that the surface phenomenology of non-Wigner-Dyson topological insulators is\na lot richer than that of their Wigner-Dyson siblings, extreme limits being\nspectrum wide quantum critical delocalization of all states vs. full\nlocalization except at the $E=0$ critical point. As part of our study we\nidentify possible experimental signatures distinguishing between these\ndifferent alternatives in transport or tunnel spectroscopy.",
        "positive": "Illumination-induced changes of the Fermi surface topology in\n  three-dimensional superlattices: The magnetoresistance of the MBE-grown GaAs/AlGaAs superlattice with Si-doped\nbarriers has been measured in tilted magnetic fields in the as-grown state, and\nafter brief illumination by a red-light diode at low temperature, T is\napproximately 0.3 K. A remarkable illumination-induced modification of\nmagnetoresistance curves has been observed, which indicates a significant\nchange of the superlattice Fermi surface topology. Analysis of\nmagnetoresistance data in terms of the tight-binding model reveals that not\nonly electron concentration and mobility have been increased by illumination,\nbut also the coupling among 2D electron layers in neighboring quantum wells has\nbeen reduced."
    },
    {
        "anchor": "Highly Controllable Qubit-Bath Coupling Based on a Sequence of\n  Resonators: Combating the detrimental effects of noise remains a major challenge in\nrealizing a scalable quantum computer. To help to address this challenge, we\nintroduce a model realizing a controllable qubit-bath coupling using a sequence\nof LC resonators. The model establishes a strong coupling to a low-temperature\nenvironment which enables us to lower the effective qubit temperature making\nground state initialization more efficient. The operating principle is similar\nto that of a recently proposed coplanar-waveguide cavity (CPW) system, for\nwhich our work introduces a complementary and convenient experimental\nrealization. The lumped-element model utilized here provides an easily\naccessible theoretical description. We present analytical solutions for some\nexperimentally feasible parameter regimes and study the control mechanism.\nFinally, we introduce a mapping between our model and the recent CPW system.",
        "positive": "Strategies and tolerances of spin transfer torque switching: Schemes of switching nanomagnetic memories via the effect of spin torque with\nvarious polarizations of injected electrons are studied. Simulations based on\nmacrospin and micromagnetic theories are performed and compared. We demonstrate\nthat switching with perpendicularly polarized current by short pulses and free\nprecession requires smaller time and energy than spin torque switching with\ncollinear in plane spin polarization; it is also found to be superior to other\nkinds of memories. We study the tolerances of switching to the magnitude of\ncurrent and pulse duration. An increased Gilbert damping is found to improve\ntolerances of perpendicular switching without increasing the threshold current,\nunlike in plane switching."
    },
    {
        "anchor": "Bell-state generation for spin qubits via dissipative coupling: We theoretically investigate the dynamics of two spin qubits interacting with\na magnetic medium. A systematic formal framework for this qubit-magnet hybrid\nsystem is developed in terms of the steady-state properties of the magnetic\nmedium. Focusing on the induced dissipative coupling between the spin qubits,\nwe show how a sizable long-lived entanglement can be established via the\nmagnetic environment, in the absence of any coherent coupling. Moreover, we\ndemonstrate that maximally-entangled two-qubit states (Bell states) can be\nachieved in this scheme when complemented by proper postselection. In this\nsituation, the time evolution of the entanglement is governed by a\nnon-Hermitian Hamiltonian, where dynamical phases are separated by an\nexceptional point. The resultant Bell state is robust against weak random\nperturbations and does not require the preparation of a particular initial\nstate. Our study may find applications in quantum information science, quantum\nspintronics, and for sensing of nonlocal quantum correlations.",
        "positive": "Sharp tunneling peaks in a parametric oscillator: quantum resonances\n  missing in the rotating wave approximation: We describe a new mechanism of tunneling between period-two vibrational\nstates of a weakly nonlinear parametrically modulated oscillator. The tunneling\nresults from resonant transitions induced by the fast oscillating terms\nconventionally disregarded in the rotating wave approximation (RWA). The\ntunneling amplitude displays resonant peaks as a function of the modulation\nfrequency; near the maxima it is exponentially larger than the RWA tunneling\namplitude."
    },
    {
        "anchor": "Milestones toward Majorana-based quantum computing: We introduce a scheme for preparation, manipulation, and readout of Majorana\nzero modes in semiconducting wires with mesoscopic superconducting islands. Our\napproach synthesizes recent advances in materials growth with tools commonly\nused in quantum-dot experiments, including gate-control of tunnel barriers and\nCoulomb effects, charge sensing, and charge pumping. We outline a sequence of\nmilestones interpolating between zero-mode detection and quantum computing that\nincludes (1) detection of fusion rules for non-Abelian anyons using either\nproximal charge sensors or pumped current; (2) validation of a prototype\ntopological qubit; and (3) demonstration of non-Abelian statistics by braiding\nin a branched geometry. The first two milestones require only a single wire\nwith two islands, and additionally enable sensitive measurements of the\nsystem's excitation gap, quasiparticle poisoning rates, residual Majorana\nzero-mode splittings, and topological-qubit coherence times. These pre-braiding\nexperiments can be adapted to other manipulation and readout schemes as well.",
        "positive": "Position operators and interband matrix elements of scalar and vector\n  potentials in the 8-band Kane model: We diagonalize the 8-band Kane Hamiltonian with a proper inclusion of the\ninterband matrix elements of the scalar and vector potentials. This leads,\namong other results, to a modification of the conventional expression for the\nspin-orbit coupling (SOC) strength in narrow-gap semiconductors with the zinc\nblende symmetry. We find that in GaAs, at low temperatures, the correct\nexpression for the SOC strength is actually twice as large as usually\nconsidered. In InSb it is $1.76$ times larger. We also provide a proper\ntreatment of the interband matrix elements of the position operator. We show\nthat the velocity operator in a crystal should be defined as a time-derivative\nof a fictitious position operator rather than the physical one. We compute the\nexpressions for both these position operators projected to the conduction band\nof the 8-band Kane model. We also derive an expression for the velocity\noperator and demonstrate that the SOC strength in it differs from the SOC\nstrength in the Hamiltonian. The ratio between them is not equal to $1$, as it\nis often assumed for the Rashba model. It does not equal $2$ either. The\ncorrect result for this ratio is given by a rational function of the parameters\nof the model. This function takes values between $4(23+3\\sqrt{2})/73\\approx\n1.49$ and $2$. Our findings modify a vast number of research results obtained\nusing the Rashba model and provide a path for a consistent treatment of the\nlatter in future applications."
    },
    {
        "anchor": "I-V characteristics of in-plane and out-of-plane strained\n  edge-hydrogenated armchair graphene nanoribbons: The effects of tensile strain on the current-voltage (I-V) characteristics of\nhydrogenated-edge armchair graphene nanoribbons (HAGNRs) are investigated by\nusing DFT theory. The strain is introduced in two different ways related to the\ntwo types of systems studied in this work: in-plane strained systems (A), and\nout-of-plane strained systems due to bending (B). These two kinds of strain\nlead to make a distinction among three cases: in-plane strained systems with\nstrained electrodes (A1) and with unstrained electrodes (A2), and out-of-plane\nhomogeneously strained systems with unstrained, fixed electrodes (B). The\nsystematic simulations to calculate the electronic transmission between two\nelectrodes were focused on systems of 8 and 11 dimers in width. The results\nshow that the differences between cases A2 and B are negligible, even though\nthe strain mechanisms are different: in the plane case, the strain is uniaxial\nalong its length, while in the bent case the strain is caused by the arc\ndeformation. Based on the study, a new type of NEMS-solid state switching\ndevice is proposed.",
        "positive": "Spin thermoelectrics in a disordered Fermi gas: We study the connection between the spin-heat and spin-charge response in a\ndisordered Fermi gas with spin-orbit coupling. It is shown that the ratio\nbetween the above responses can be expressed as the thermopower $S=-(\\pi\nk_B)^2T\\sigma'/3e\\sigma$ times a number $R_s$ which depends on the strength and\ntype of the spin-orbit couplings considered. The general results are\nillustrated by examining different two-dimensional electron or hole systems\nwith different and competing spin-orbit mechanisms, and we conclude that a\nmetallic system could prove much more efficient as a heat-to-spin than as a\nheat-to-charge converter."
    },
    {
        "anchor": "Weak localization in a system with a barrier: Dephasing and weak Coulomb\n  blockade: We non-perturbatively analyze the effect of electron-electron interactions on\nweak localization (WL) in relatively short metallic conductors with a tunnel\nbarrier. We demonstrate that the main effect of interactions is electron\ndephasing which persists down to T=0 and yields suppression of WL correction to\nconductance below its non-interacting value. Our results may account for recent\nobservations of low temperature saturation of the electron decoherence time in\nquantum dots.",
        "positive": "Spin-wave dynamics and symmetry breaking in an artificial spin ice: Artificial spin ices are periodic arrangements of interacting nanomagnets\nsuccessfully used to investigate emergent phenomena in the presence of\ngeometric frustration. Recently, it has been shown that artificial spin ices\ncan be used as building blocks for creating functional materials, such as\nmagnonic crystals, and support a large number of programmable magnetic states.\nWe investigate the magnetization dynamics in a system exhibiting anisotropic\nmagnetostatic interactions owing to locally broken structural inversion\nsymmetry. We find a rich spin-wave spectrum and investigate its evolution in an\nexternal magnetic field. We determine the evolution of individual modes, from\nbuilding blocks up to larger arrays, highlighting the role of symmetry breaking\nin defining the mode profiles. Moreover, we demonstrate that the mode spectra\nexhibit signatures of long-range interactions in the system. These results\ncontribute to the understanding of magnetization dynamics in spin ices beyond\nthe kagome and square ice geometries and are relevant for the realization of\nreconfigurable magnonic crystals based on spin ices."
    },
    {
        "anchor": "Coherent states in the symmetric gauge for graphene under a constant\n  perpendicular magnetic field: In this work we describe semiclassical states in graphene under a constant\nperpendicular magnetic field by constructing coherent states in the\nBarut-Girardello sense. Since we want to keep track of the angular momentum,\nthe use of the symmetric gauge and polar coordinates seemed the most logical\nchoice. Different classes of coherent states are obtained by means of the\nunderlying algebra system, which consists of the direct sum of two\nHeisenberg-Weyl algebras. The most interesting cases are a kind of partial\ncoherent states and the coherent states with a well-defined total angular\nmomentum.",
        "positive": "High-temperature superfuidity of the two-component Bose gas in a TMDC\n  bilayer: The high-temperature superfluidity of two-dimensional dipolar excitons in two\nparallel TMDC layers is predicted. We study Bose-Einstein condensation in the\ntwo-component system of dipolar A and B excitons. The effective mass, energy\nspectrum of the collective excitations, the sound velocity and critical\ntemperature are obtained for different TMDC materials. It is shown that in the\nBogolubov approximation the sound velocity in the two-component dilute exciton\nBose gas is always larger than in any one-component. The difference between the\nsound velocities for two-component and one-component dilute gases is caused by\nthe fact that the sound velocity for two-component system depends on the\nreduced mass of A and B excitons, which is always smaller than the individual\nmass of A or B exciton. Due to this fact, the critical temperature Tc for\nsuperfluidity for the two-component exciton system in TMDC bilayer is about one\norder of magnitude higher than Tc in any one-component exciton system. We\npropose to observe the superfluidity of two-dimensional dipolar excitons in two\nparallel TMDC layers, which causes two opposite superconducting currents in\neach TMDC layer."
    },
    {
        "anchor": "Crossover between the Dense Electron-Hole Phase and the BCS Excitonic\n  Phase in Quantum Dots: Second order perturbation theory and a Lipkin-Nogami scheme combined with an\nexact Monte Carlo projection after variation are applied to compute the\nground-state energy of $6\\le N\\le 210$ electron-hole pairs confined in a\nparabolic two-dimensional quantum dot. The energy shows nice scaling properties\nas N or the confinement strength is varied. A crossover from the high-density\nelectron-hole phase to the BCS excitonic phase is found at a density which is\nroughly four times the close-packing density of excitons.",
        "positive": "Shot Noise of Non-Interacting Composite Fermions: A simple equivalent circuit, which describes transport properties of a Two\nDimensional Electron Gas in the Fractional Quantum Hall regime is presented.\nThe physical justifications for this equivalent circuit are discussed in the\nframe work of the non-interacting Composite Fermions model. Quantum Shot Noise\nat an arbitrary filling factor and temperature is readily calculated."
    },
    {
        "anchor": "Controllable spin-dependent transport in armchair graphene nanoribbon\n  structures: Using the non-equilibrium Green's functions formalism in a tight binding\nmodel, the spin-dependent transport in armchair graphene nanoribbon (GNR)\nstructures controlled by a ferromagnetic gate is investigated. Beyond the\noscillatory behavior of conductance and spin polarization with respect to the\nbarrier height, which can be tuned by the gate voltage, we especially analyze\nthe effect of width-dependent band gap and the nature of contacts. The\noscillation of spin polarization in the GNRs with a large band gap is strong in\ncomparison with 2D-graphene structures. Very high spin polarization (close to\n100%) is observed in normal-conductor/graphene/normal-conductor junctions.\nMoreover, we find that the difference of electronic structure between normal\nconductor and graphene generates confined states in the device which have a\nstrong influence on the transport quantities. It suggests that the device\nshould be carefully designed to obtain high controllability of spin current.",
        "positive": "Interplay between Josephson effect and magnetic interactions in double\n  quantum dots: We analyze the magnetic and transport properties of a double quantum dot\ncoupled to superconducting leads. In addition to the possible phase transition\nto a $\\pi$ state, already present in the single dot case, this system exhibits\na richer magnetic behavior due to the competition between Kondo and inter-dot\nantiferromagnetic coupling. We obtain results for the Josephson current which\nmay help to understand recent experiments on superconductor-metallofullerene\ndimer junctions. We show that in such a system the Josephson effect can be used\nto control its magnetic configuration."
    },
    {
        "anchor": "Coherent Electron-Phonon Coupling in Tailored Quantum Systems: The coupling between a two-level system and its environment leads to\ndecoherence. Within the context of coherent manipulation of electronic or\nquasiparticle states in nanostructures, it is crucial to understand the sources\nof decoherence. Here, we study the effect of electron-phonon coupling in a\ngraphene and an InAs nanowire double quantum dot. Our measurements reveal\noscillations of the double quantum dot current periodic in energy detuning\nbetween the two levels. These periodic peaks are more pronounced in the\nnanowire than in graphene, and disappear when the temperature is increased. We\nattribute the oscillations to an interference effect between two alternative\ninelastic decay paths involving acoustic phonons present in these materials.\nThis interpretation predicts the oscillations to wash out when temperature is\nincreased, as observed experimentally.",
        "positive": "Trial Wavefunctions for \u03bd= 1/2 + 1/2 Quantum Hall Bilayers: Quantum Hall bilayer systems at filling fractions near \\nu = 1/2 + 1/2\nundergo a transition from a compressible phase with strong intralayer\ncorrelation to an incompressible phase with strong interlayer correlations as\nthe layer separation d is reduced below some critical value. Deep in the\nintralayer phase (large separation) the system can be interpreted as a fluid of\ncomposite fermions (CFs), whereas deep in the interlayer phase (small\nseparation) the system can be interpreted as a fluid of composite bosons (CBs).\nThe focus of this paper is to understand the states that occur for intermediate\nlayer separation by using trial variational wavefunctions. We consider two main\nclasses of wavefunctions. In the first class, previously introduced by Moller\net al. [PRL {\\bf 101}, 176803 (2008)], we consider interlayer BCS pairing of\ntwo independent CF liquids. We find that these wavefunctions are exceedingly\ngood for d >~ \\ell_0 with \\ell_0 the magnetic length. The second class of\nwavefunctions naturally follows the reasoning of Simon et al. [PRL {\\bf 91},\n046803 (2003)] and generalizes the idea of pairing wavefunctions by allowing\nthe CFs also to be replaced continuously by CBs. This generalization allows us\nto construct exceedingly good wavefunctions for interlayer spacings of d <~\n\\ell_0, as well. The accuracy of the wavefunctions discussed in this work,\ncompared with exact diagonalization, approaches that of the celebrated Laughlin\nwavefunction."
    },
    {
        "anchor": "Computational study of heavy group IV elements (Ge, Sn, Pb) triangular\n  lattice atomic layers on SiC(0001) surface: Group IV heavy elements atomic layers are expected to show an interesting\nphysical properties due to their large spin-orbit coupling (SOC). Using density\nfunctional theory (DFT) calculations with/without SOC we investigate the\nvariation of group IV heavy elements overlayers, namely dense triangular\nlattice atomic layers (TLAL) on the surface of SiC(0001) semiconductor. The\npossibility of such layers formation and their properties have not been\naddressed before. Here we show, that these layers may indeed be stable and,\nowing to peculiar bonding configuration, exhibit robust Dirac-like energy bands\noriginating from $p_x+p_y$ orbitals and localized mostly within the layer, and\n$p_z$ band localized outside the layer and interacting with SiC substrate. We\nfound that a $T_1$ adsorption site is most favorable for such TLAL structure\nand this results in an unusual SOC-induced spin polarization of the states\naround $\\bar{K}$ points of Brillouin zone, namely the coexistence of Rashba-\nand Zeeman-like spin polarization of different states. We explain this\nphenomena in terms of symmetry of partial electronic density rather than\nsymmetry of atomic structure.",
        "positive": "Effect of coordination on topological phases on self-similar structures: Topologically non-trivial phases have recently been reported on self-similar\nstructures. Here, we investigate the effect of local structure, specifically\nthe role of the coordination number, on the topological phases on self-similar\nstructures embedded in two dimensions. We study a geometry dependent model on\ntwo self-similar structures having different coordination numbers, constructed\nfrom the Sierpinski Gasket. For different non-spatial symmetries present in the\nsystem, we numerically study and compare the phases on both the structures. We\ncharacterize these phases by the localization properties of the single-particle\nstates, their robustness to disorder, and by using a real-space topological\nindex. We find that both the structures host topologically non-trivial phases\nand the phase diagrams are different on the two structures. This suggests that,\nin order to extend the present classification scheme of topological phases to\nnon-periodic structures, one should use a framework which explicitly takes the\ncoordination of sites into account."
    },
    {
        "anchor": "Motion transduction with thermo-mechanically squeezed graphene resonator\n  modes: There is a recent surge of interest in amplification and detection of tiny\nmotion in the growing field of opto and electro mechanics. Here, we demonstrate\nwidely tunable, broad bandwidth and high gain all-mechanical motion amplifiers\nbased on graphene/Silicon Nitride (SiNx) hybrids. In these devices, a tiny\nmotion of a large-area SiNx membrane is transduced to a much larger motion in a\ngraphene drum resonator coupled to SiNx. Furthermore, the thermal noise of\ngraphene is reduced (squeezed) through parametric tension modulation. The\nparameters of the amplifier are measured by photothermally actuating SiNx and\ninterferometrically detecting graphene displacement. We obtain displacement\npower gain of 38 dB and demonstrate 4.7 dB of squeezing resulting in a\ndetection sensitivity of 3.8 fm per square root Hz, close to the thermal noise\nlimit of SiNx.",
        "positive": "Lithographic mechanical break junctions for single-molecule measurements\n  in vacuum: possibilities and limitations: We have investigated electrical transport through the molecular model systems\nbenzenedithiol, benzenediamine, hexanedithiol and hexanediamine. Conductance\nhistograms under different experimental conditions indicate that measurements\nusing mechanically controllable break junctions in vacuum are limited by the\nsurface density of molecules at the contact. Hexanedithiol histograms typically\nexhibit a broad peak around 7 * 10^{-4} G_0. In contrast to recent results on\nSTM-based break junctions in solution we find that the spread in\nsingle-molecule conductance is not reduced by amino anchoring groups.\nHistograms of hexanediamine exhibit a very wide peak around 4 * 10^{-4} G_0.\nFor both benzenedithiol and benzenediamine we observe a large variability in\nlow-bias conductance. We attribute these features to the slow breaking of the\nlithographic mechanically controllable break junctions and the absence of a\nsolvent that may enable molecular readsorption after bond breaking.\nNevertheless, we have been able to acquire reproducible current-voltage\ncharacteristics of benzenediamine and benzenedithiol using a statistical\nmeasurement approach. Benzenedithiol measurements yield a conductance gap of\nabout 0.9 V at room temperature and 0.6 V at 77 K. In contrast, the\ncurrent-voltage characteristics of benzenediamine-junctions typically display\nconductance gaps of about 0.9 V at both temperatures."
    },
    {
        "anchor": "Shot noise in resonant tunneling through a zero-dimensional state with a\n  complex energy spectrum: We investigate the noise properties of a GaAs/AlGaAs resonant tunneling\nstructure at bias voltages where the current characteristic is determined by\nsingle electron tunneling. We discuss the suppression of the shot noise in the\nframework of a coupled two-state system. For large bias voltages we observed\nsuper-Poissonian shot noise up to values of the Fano factor $\\alpha \\approx\n10$.",
        "positive": "Eigenmodes of magnetic skyrmion lattices: We explore the interplay between topology and eigenmodes by changing the\nstabilizing mechanism of skyrmion lattices (skX). We focus on two prototypical\nultrathin films hosting an hexagonal (Pd/Fe/Ir(111)) and a square (Fe/Ir(111))\nskyrmion lattice, which can both be described by an extended Heisenberg\nHamiltonian. We first examine whether the Dzyaloshinkskii-Moriya, or the\nexchange interaction as the leading energy term affects the modes of the\nhexagonal skX of Pd/Fe/Ir(111). In all cases, we find that the lowest frequency\nmodes correspond to internal degrees of freedom of individual skyrmions, and\nsuggest a classification based on azimuthal and radial numbers $(l,p)$, with up\nto $l=6$, and $p=2$. We also show that the gyration behavior induced by an\nin-plane field corresponds to the excitation of $l=1$ deformation modes with\nvarying radial numbers. Second, we examine the square lattice of skyrmions of\nFe/Ir(111). Its stabilization mechanism is dominated by the 4-spin interaction.\nAfter relaxation, the unit cell does not carry a topological charge, and the\neigenmodes do not correspond to internal skyrmion deformations. By reducing the\n4-spin interaction, the integer topological charge is recovered, but the charge\ncarriers do not possess internal degrees of freedom, nor are they separated by\nenergy barriers. We conclude that a 4-spin dominated Hamiltonian does not yield\nskyrmion lattice solutions, and that therefore, a nontrivial topology does not\nimply the existence of skyrmions."
    },
    {
        "anchor": "Phase Coexistence and Transitions between Antiferromagnetic and\n  Ferromagnetic States in a Synthetic Antiferromagnet: In synthetic antiferromagnets (SAFs) the combination of antiferromagnetic\norder and synthesis using conventional sputtering techniques is combined to\nproduce systems that are advantageous for spintronics applications. Here we\npresent the preparation and study of SAF multilayers possessing both\nperpendicular magnetic anisotropy and the Dzyaloshinskii-Moriya interaction.\nThe multilayers have an antiferromagnetically (AF) aligned ground state but can\nbe forced into a full ferromagnetic (FM) alignment by applying an out-of-plane\nfield $\\sim 100$~mT. We study the spin textures in these multilayers in their\nground state as well as around the transition point between the AF and FM\nstates, at fields $\\sim 40$~mT, by imaging the spin textures using\ncomplementary methods: photo-emission electron, magnetic force, and Lorentz\ntransmission electron microscopies. The transformation into a FM state by field\nproceeds by a nucleation and growth process, where first skyrmionic nuclei\nform, which broaden into regions containing a FM-aligned labyrinth pattern that\neventually occupies the whole film. This process remarkably occurs without any\nsignificant change in the net magnetic moment of the multilayer. The mix of AF-\nand FM-aligned regions on the micron scale in the middle of this transition is\nreminiscent of a first-order phase transition that exhibits phase coexistence.\nThese results are important for guiding the design of spintronic devices using\nchiral magnetic textures made from SAFs.",
        "positive": "A unified drift-diffusion theory for transverse spin currents in spin\n  valves, domain walls and other textured magnets: Spins transverse to the magnetization of a ferromagnet only survives over a\nshort distance. We develop a drift-diffusion approach that captures the main\nfeatures of transverse spin effects in systems with arbitrary spin textures\n(vortices, domain walls) and generalizes the Valet-Fert theory. In addition to\nthe standard characteristic lengths (mean free path for majority and manority\nelectrons, spin diffusion length), the theory introduces two lengths scales,\nthe transverse spin coherence length and the (Larmor) spin precession length.\nWe show how those lengths can be extracted from ab-initio calculations or\nmeasured with giant magneto-resistance experiments. In long (adiabatic) domain\nwalls, we provide an analytic formula that expresses the so called\n\"non-adiabatic\" (or field like) torque in term of those lengths scales.\nHowever, this \"non adiabatic\" torque is no longer a simple material parameter\nand depends on the actual spin texture: in thin (< 10nm) domain walls, we\nobserve very significant deviations from the adiabatic limit."
    },
    {
        "anchor": "Noise correlations, entanglement, and Bell inequalities: The aim of this chapter is to describe two situations where positive noise\ncorrelations can be directly monitored using a transport experiment, either\nwith a superconductor or with a correlated electron system. To be more precise,\nthe present text reflects the presentations made by the three authors during\nthe Delft NATO workshop. Bell inequalities and quantum mechanical non-locality\nwith electrons injected from a superconductor will be addressed first. Next,\nnoise correlations will be computed in a carbon nanotube where electrons are\ninjected in the bulk from a STM tip. The first topic is the result of an\nongoing collaboration with G. Lesovik and G. Blatter over the years. The\nunifying theme is that in both branched quantum circuits, entanglement is\nexplicit and can be illustrated via noise correlations. Entanglement can be\nachieved either for pairs of electrons in the case of superconductor sources\nconnected to Fermi liquid leads, or alternatively for pairs of quasiparticle\nexcitations of the correlated electron fluid.",
        "positive": "Electronic structure of few-electron concentric double quantum rings: The ground state structure of few-electron concentric double quantum rings is\ninvestigated within the local spin density approximation. Signatures of\ninter-ring coupling in the addition energy spectrum are identified and\ndiscussed. We show that the electronic configurations in these structures can\nbe greatly modulated by the inter-ring distance: At short and long distances\nthe low-lying electron states localize in the inner and outer rings,\nrespectively, and the energy structure is essentially that of an isolated\nsingle quantum ring. However, at intermediate distances the electron states\nlocalized in the inner and the outer ring become quasi-degenerate and a rather\nentangled, strongly-correlated system is formed."
    },
    {
        "anchor": "Accurate and efficient description of interacting carriers in quantum\n  nanostructures by selected configuration interaction and perturbation theory: We present a method to calculate many-body states of interacting carriers in\nmillion atom quantum nanostructures based on atomistic tight-binding\ncalculations and a combination of iterative selection of configurations and\nperturbation theory. This method enables investigations of large excitonic\ncomplexes and multi-electron systems with near full configuration interaction\naccuracy, even though only a small subspace of the full many-body Hilbert space\nis sampled, thus saving orders of magnitudes in computational resources.\nImportant advantages of this method are that the convergence is controlled by a\nsingle parameter, the threshold, and that ground and excited states can be\ntreated on an equal footing. We demonstrate the extreme efficiency of the\nmethod by numerical studies of complexes composed of up to 13 excitons, which\nrequires filling of states up to the fourth electronic shell. We find that the\nmethod generally converges fast as a function of the threshold, profiting from\na significant enhancement due to the perturbative corrections. The role of the\nchoice of single-particle basis states is discussed. It is found that the\nalgorithm converges faster in the Hartree-Fock basis only for highly charged\nsystems, where Coulomb repulsion dominates. Finally, based on the observation\nthat second order perturbative energy corrections only depend on off-diagonal\nelements of the many-body Hamiltonian, we present a way to accurately calculate\nmany-body states that requires only a relatively small number of Coulomb matrix\nelements.",
        "positive": "Observation of photonic antichiral edge states: Chiral edge states are a hallmark feature of two-dimensional topological\nmaterials. Such states must propagate along the edges of the bulk either\nclockwise or counterclockwise, and thus produce oppositely propagating edge\nstates along the two parallel edges of a strip sample. However, recent theories\nhave predicted a counterintuitive picture, where the two edge states at the two\nparallel strip edges can propagate in the same direction; these anomalous\ntopological edge states are named as antichiral edge states. Here we report the\nexperimental observation of antichiral edge states in a gyromagnetic photonic\ncrystal. The crystal consists of gyromagnetic cylinders in a honeycomb lattice,\nwith the two triangular sublattices magnetically biased in opposite directions.\nWith microwave measurement, unique properties of antichiral edge states have\nbeen observed directly, which include the titled dispersion, the chiral-like\nrobust propagation in samples with certain shapes, and the scattering into\nbackward bulk states at certain terminations. These results extend and\nsupplement the current understanding of chiral edge states."
    },
    {
        "anchor": "Ultra-fast Vapor Generation by a Graphene Nano-ratchet: Vapor generation is of prime importance for a broad range of applications:\ndomestic water heating, desalination and wastewater treatment, etc. However,\nthe slow and low efficiency evaporation limits their development. In this\npaper, we proposed a nano-ratchet, multilayer graphene with cone-shaped\nnanopores (MGCN), to accelerate the vapor generation. By performing molecular\ndynamics simulations, we found that the air molecules spontaneously transport\nacross MGCN and form a remarkable pressure difference, 21kPa, between the two\nsides of MGCN. Besides, we studied the dependence of pressure difference on the\nambient temperature and the geometry of MGCN in detail. By further analysis of\nthe diffusive transport, we identified that the pressure difference relates to\nthe competition between ratchet transport and Knudsen diffusion. The\nsignificant pressure difference could lead to 15 times enhancement of vapor\ngeneration at least, which shows the wide applications of this nano-ratchet.",
        "positive": "Degeneracy lifting of Majorana bound states due to electron-phonon\n  interactions: We study theoretically how electron-phonon interaction affects the energies\nand level broadening (inverse lifetime) of Majorana bound states (MBSs) in a\nclean topological nanowire at low temperatures. At zero temperature, the energy\nsplitting between the right and left MBSs remains exponentially small with\nincreasing nanowire length $L$. At finite temperatures, however, the absorption\nof thermal phonons leads to the broadening of energy levels of the MBSs that\ndoes not decay with system length, and the coherent absorption/emission of\nphonons at opposite ends of the nanowire results in MBSs energy splitting that\ndecays only as an inverse power-law in $L$. Both effects remain exponential in\ntemperature. In the case of quantized transverse motion of phonons, the\npresence of Van Hove singularities in the phonon density of states causes\nadditional resonant enhancement of both the energy splitting and the level\nbroadening of the MBSs. This is the most favorable case to observe the\nphonon-induced energy splitting of MBSs as it becomes much larger than the\nbroadening even if the topological nanowire is much longer than the coherence\nlength. We also calculate the charge and spin associated with the energy\nsplitting of the MBSs induced by phonons. We consider both a spinless\nlow-energy continuum model, which we evaluate analytically, as well as a\nspinful lattice model for a Rashba nanowire, which we evaluate numerically."
    },
    {
        "anchor": "Exciton absorption in narrow armchair graphene nanoribbons: We develop an analytical approach to the exciton optical absorption for\nnarrow gap armchair graphene nanoribbons (AGNR). We focus on the regime of\ndominant size quantization in combination with the attractive electron-hole\ninteraction. An adiabatic separation of slow and fast motions leads via the\ntwo-body Dirac equation to the isolated and coupled subband approximations.\nDiscrete and continuous exciton states are in general coupled and form quasi\nRydberg series of purely discrete and resonance type character. Corresponding\noscillator strengths and widths are derived. We show that the exciton peaks are\nblue-shifted, become broader and increase in magnitude upon narrowing the\nribbon. At the edge of a subband the singularity related to the 1D density of\nstates is transformed into finite absorption via the presence of the exciton.\nOur analytical results are in good agreement with those obtained by other\nmethods including numerical approaches. Estimates of the expected experimental\nvalues are provided for realistic AGNRs.",
        "positive": "Evidence of Andreev blockade in a double quantum dot coupled to a\n  superconductor: We design and investigate an experimental system capable of entering an\nelectron transport blockade regime in which a spin-triplet localized in the\npath of current is forbidden from entering a spin-singlet superconductor. To\nstabilize the triplet a double quantum dot is created electrostatically near a\nsuperconducting lead in an InAs nanowire. The dots are filled stochastically\nwith electrons of either spin. The superconducting lead is a molecular beam\nepitaxy grown Al shell. The shell is etched away over a wire segment to make\nroom for the double dot and the normal metal gold lead. The quantum dot closest\nto the normal lead exhibits Coulomb diamonds, the dot closest to the\nsuperconducting lead exhibits Andreev bound states and an induced gap. The\nexperimental observations compare favorably to a theoretical model of Andreev\nblockade, named so because the triplet double dot configuration suppresses\nAndreev reflections. Observed leakage currents can be accounted for by finite\ntemperature. We observe the predicted quadruple level degeneracy points of high\ncurrent and a periodic conductance pattern controlled by the occupation of the\nnormal dot. Even-odd transport asymmetry is lifted with increased temperature\nand magnetic field. This blockade phenomenon can be used to study spin\nstructure of superconductors. It may also find utility in quantum computing\ndevices that utilize Andreev or Majorana states."
    },
    {
        "anchor": "Electronic structure of interfaces between hexagonal and rhombohedral\n  graphite: The electronic structure including energy bands, band weights, and local\ndensity of states (LDOS) of interfaces between hexagonal (AB) and rhombohedral\n(ABC) graphite has been has been calculated. The full-potential local-orbital\ncode (FPLO) and the generalized gradient approximation (GGA) to the density\nfunctional theory has been used. Both of the two existing interface structures\nhost (localized) interface bands, which are located around the K-point in the\nBrillouin zone, and which give rise to strong peaks in the LDOS at the Fermi\nenergy. All interface bands near the Fermi energy are localized at monomers\n(single atoms with dangling $p_z$ bonds), whereas those around 0.5 eV belong to\n$p_z$-bonded trimers, which are created by the the interface and which are not\nfound in the two adjacent bulk substances. There is also an interface band at\nthe (AB) side of the interface which resembles one of the interface states near\na stacking fault in (AB) graphite.",
        "positive": "Self-aligned photonic defect microcavities with site-controlled quantum\n  dots: Despite the superiority in quantum properties, self-assembled semiconductor\nquantum dots face challenges in terms of scalable device integration because of\ntheir random growth positions, originating from the Stranski-Krastanov growth\nmode. Even with existing site-controlled growth techniques, for example,\nnanohole or buried stressor concepts, a further lithography and etching step\nwith high spatial alignment requirements isnecessary to accurately integrate\nQDs into the nanophotonic devices. Here, we report on the fabrication and\ncharacterization of strain-induced site-controlled microcavities where\nsite-controlled quantum dots are positioned at the antinode of the optical mode\nfield in a self-aligned manner without the need of any further nano-processing.\nWe show that the Q-factor, mode volume, height, and the ellipticity of\nsite-controlled microcavities can be tailored by the size of an integrated\nAlAs/Al2O3 buried stressor, with an opening ranging from 1 to 4 $\\mu$m. Lasing\nsignatures, including super-linear input-output response, linewidth narrowing\nnear threshold, and gain competition above threshold, are observed for a\n3.6-$\\mu$m self-aligned cavity with a Q-factor of 18000. Furthermore, by\nwaiving the rather complex lateral nano-structuring usually performed during\nthe fabrication process of micropillar lasers and vertical-cavity surface\nemitting lasers, quasi-planar site-controlled cavities exhibit no detrimental\neffects of excitation power induced heating and thermal rollover. Our\nstraightforward deterministic nanofabrication concept of high-quality quantum\ndot microcavities integrates seamlessly with the industrial-matured\nmanufacturing process and the buried-stressor techniques, paving the way for\nexceptional scalability and straightforward manufacturing of high-\\b{eta}\nmicrolasers and bright quantum light sources."
    },
    {
        "anchor": "Quantitative Measure of Hysteresis for Memristors Through Explicit\n  Dynamics: We introduce a mathematical framework for the analysis of the input-output\ndynamics of externally driven memristors. We show that, under general\nassumptions, their dynamics comply with a Bernoulli differential equation and\nhence can be nonlinearly transformed into a formally solvable linear equation.\nThe Bernoulli formalism, which applies to both charge- and flux-controlled\nmemristors when either current- or voltage-driven, can, in some cases, lead to\nexpressions of the output of the device as an explicit function of the input.\nWe apply our framework to obtain analytical solutions of the i-v\ncharacteristics of the recently proposed model of the Hewlett-Packard memristor\nunder three different drives without the need for numerical simulations. Our\nexplicit solutions allow us to identify a dimensionless lumped parameter that\ncombines device-specific parameters with properties of the input drive. This\nparameter governs the memristive behavior of the device and, consequently, the\namount of hysteresis in the i-v. We proceed further by defining formally a\nquantitative measure for the hysteresis of the device for which we obtain\nexplicit formulas in terms of the aforementioned parameter and we discuss the\napplicability of the analysis for the design and analysis of memristor devices.",
        "positive": "Microfluidic and Nanofluidic Cavities for Quantum Fluids Experiments: The union of quantum fluids research with nanoscience is rich with\nopportunities for new physics. The relevant length scales in quantum fluids,\n3He in particular, are comparable to those possible using microfluidic and\nnanofluidic devices. In this article, we will briefly review how the physics of\nquantum fluids depends strongly on confinement on the microscale and nanoscale.\nThen we present devices fabricated specifically for quantum fluids research,\nwith cavity sizes ranging from 30 nm to 11 microns deep, and the\ncharacterization of these devices for low temperature quantum fluids\nexperiments."
    },
    {
        "anchor": "Two dimensional topological insulator in quantizing magnetic fields: The effect of quantizing magnetic field on the electron transport is\ninvestigated in a two dimensional topological insulator (2D TI) based on a 8 nm\n(013) HgTe quantum well (QW). The local resistance behavior is indicative of a\nmetal-insulator transition at $B\\approx 6$ T. On the whole the experimental\ndata agrees with the theory according to which the helical edge states\ntransport in a 2D TI persists from zero up to a critical magnetic field $B_c$\nafter which a gap opens up in the 2D TI spectrum.",
        "positive": "A Fiber-coupled Scanning Magnetometer with Nitrogen-Vacancy Spins in a\n  Diamond Nanobeam: Magnetic imaging with nitrogen-vacancy (NV) spins in diamond is becoming an\nestablished tool for studying nanoscale physics in condensed matter systems.\nHowever, the optical access required for NV spin readout remains an important\nhurdle for operation in challenging environments such as millikelvin cryostats\nor biological systems. Here, we demonstrate a scanning-NV sensor consisting of\na diamond nanobeam that is optically coupled to a tapered optical fiber. This\nnanobeam sensor combines a natural scanning-probe geometry with high-efficiency\nthrough-fiber optical excitation and readout of the NV spins. We demonstrate\nthrough-fiber optically interrogated electron spin resonance and\nproof-of-principle magnetometry operation by imaging spin waves in an\nyttrium-iron-garnet thin film. Our scanning-nanobeam sensor can be combined\nwith nanophotonic structuring to control the light-matter interaction strength,\nand has potential for applications that benefit from all-fiber sensor access\nsuch as millikelvin systems."
    },
    {
        "anchor": "Reconfigurable spin wave band structure of artificial square spin ice: Artificial square spin ices are structures composed of magnetic elements\narranged on a geometrically frustrated lattice and located on the sites of a\ntwo-dimensional square lattice, such that there are four interacting magnetic\nelements at each vertex. Using a semi-analytical approach, we show that square\nspin ices exhibit a rich spin wave band structure that is tunable both by\nexternal magnetic fields and the configuration of individual elements. Internal\ndegrees of freedom can give rise to equilibrium states with bent magnetization\nat the edges leading to characteristic excitations; in the presence of\nmagnetostatic interactions these form separate bands analogous to impurity\nbands in semiconductors. Full-scale micromagnetic simulations corroborate our\nsemi-analytical approach. Our results show that artificial square spin ices can\nbe viewed as reconfigurable and tunable magnonic crystals that can be used as\nmetamaterials for spin-wave-based applications at the nanoscale.",
        "positive": "Gyrotropic magnetic effect and the magnetic moment on the Fermi surface: The current density ${\\bf j}^{\\rm{\\bf B}}$ induced in a clean metal by a\nslowly-varying magnetic field ${\\bf B}$ is formulated as the low-frequency\nlimit of natural optical activity, or natural gyrotropy. Working with a\nmultiband Pauli Hamiltonian, we obtain from the Kubo formula a simple\nexpression for $\\alpha^{\\rm gme}_{ij}=j^{\\rm{\\bf B}}_i/B_j$ in terms of the\nintrinsic magnetic moment (orbital plus spin) of the Bloch electrons on the\nFermi surface. An alternate semiclassical derivation provides an intuitive\npicture of the effect, and takes into account the influence of scattering\nprocesses in dirty metals. This \"gyrotropic magnetic effect\" is fundamentally\ndifferent from the chiral magnetic effect driven by the chiral anomaly and\ngoverned by the Berry curvature on the Fermi surface, and the two effects are\ncompared for a minimal model of a Weyl semimetal. Like the Berry curvature, the\nintrinsic magnetic moment should be regarded as a basic ingredient in the\nFermi-liquid description of transport in broken-symmetry metals."
    },
    {
        "anchor": "Progressive suppression of spin relaxation in 2D channels of finite\n  width: We have investigated spatio-temporal kinetics of electron spin polarization\nin semiconductor narrow 2D strip and explored the ability to manipulate spin\nrelaxation. Information about spin of the conduction electrons and mechanisms\nof spin rotation is incorporated into transport Monte Carlo simulation program.\nA model problem, involving linear-in-k splitting of the conduction band,\nresponsible for the D'yakonov-Perel' mechanism of spin relaxation in the\nzinc-blende semiconductors and heterostructures, is solved numerically to yield\nthe decay of spin polarization of an ensemble of electrons in the 2D channel of\nfinite width. For very wide channels, a conventional 2D value of spin\nrelaxation is obtained. With decreasing channel width the relaxation time\nsoares rapidly by orders of magnitude. Surprisingly, the cross-over point\nbetween 2D and quasi-1D behavior is found to be at tens of electron mean-free\npaths. Thus, classically wide channels can effectively suppress electron spin\nrelaxation.",
        "positive": "Microwave absorption in a 2D topological insulators with a developed\n  network of edge states: The 2D HgTe quantum well is analyzed based on the assumption that the width\nfluctuations convert the system to a random mixture of domains with positive\nand negative energy gaps. The borders between ordinary and topological\ninsulator phases form a network of the edge states covering the overall sample.\nThe optical transitions within the edge states yield the 2D absorption. The\nqualitative consideration is based on the model of optical intraedge\ntransitions in curved edge states together with the percolation arguments."
    },
    {
        "anchor": "A versatile platform for graphene nanoribbon synthesis, electronic\n  decoupling, and spin polarized measurements: The on-surface synthesis of nano-graphenes has led the charge in prototyping\nstructures with perspectives beyond silicon-based technology. Following reports\nof open-shell systems in graphene-nanoribbons (GNR), a flurry of research\nactivities is directed at investigating their magnetic properties with a keen\neye for spintronic applications. Although the synthesis of nano-graphenes is\nusually straightforward on gold, it is difficult to use it for electronic\ndecoupling and spin-polarized measurements. Using a binary alloy Cu3Au(111), we\nshow how to combine the efficient gold-like nano-graphene formation with spin\npolarization and electronic decoupling known from copper. We prepare copper\noxide layers, demonstrate thermally and tip-assisted synthesis of GNR and grow\nthermally stable magnetic Co islands. We functionalize the tip of a scanning\ntunneling microscope with carbon-monoxide, nickelocene, or attach Co clusters\nfor high-resolution imaging, magnetic sensing, or spin-polarized measurements.\nThis versatile platform will be a valuable tool in the advanced study of\nmagnetic nano-graphenes.",
        "positive": "Is the concept of the non-Hermitian effective Hamiltonian relevant in\n  the case of potential scattering?: We examine the notion and properties of the non-Hermitian effective\nHamiltonian of an unstable system using as an example potential resonance\nscattering with a fixed angular momentum. We present a consistent self-adjoint\nformulation of the problem of scattering on a finite-range potential, which is\nbased on separation of the configuration space on two, internal and external,\nsegments. The scattering amplitude is expressed in terms of the resolvent of a\nnon-Hermitian operator H. The explicit form of this operator depends both on\nthe radius of separation and the boundary conditions at this place which can be\nchosen in many different ways. We discuss this freedom and show explicitly that\nthe physical scattering amplitude is, nevertheless, unique though not all\nchoices are equally adequate from the physical point of view. The\nenergy-dependent operator H should not be confused with the non-Hermitian\neffective Hamiltonian H_{eff} exploited usually to describe interference of\noverlapping resonances. We apply the developed formalism to a chain of L\ndelta-barriers whose solution is also found independently in a closed form. For\na fixed band of L overlapping resonances, the smooth energy dependence of H can\nbe ignored so that complex eigenvalues of the LxL submatrix H_{eff} define the\nenergies and widths of the resonances.We construct H_{eff} for the two commonly\nconsidered types of the boundary conditions (Neumann and Dirichlet) for the\ninternal motion. Formation in the outer well of a short-lived doorway state is\nexplicitly demonstrated together with the appearance of L-1 long-lived states\ntrapped in the inner part of the chain."
    },
    {
        "anchor": "Spin revolution: The classical laws of physics are usually invariant under time reversal.\nHere, we reveal a novel class of magnetomechanical effects rigorously breaking\ntime-reversal symmetry. The effect is based on the mechanical rotation of a\nhard magnet around its magnetization axis in the presence of friction and an\nexternal magnetic field, which we call spin revolution. The physical reason for\ntime-reversal symmetry breaking is the spin revolution and not the dissipation.\nThe time-reversal symmetry breaking leads to a variety of unexpected effects\nincluding upward propulsion on vertical surfaces defying gravity as well as\nmagnetic gyroscopic motion that is perpendicular to the applied force. In\ncontrast to the spin, the angular momentum of spin revolution can be parallel\nor antiparallel to the equilibrium magnetization. The spin revolution emerges\nspontaneously, without external rotations, and offers various applications in\nareas such as magnetism, robotics and energy harvesting.",
        "positive": "A linear algebra-based approach to understanding the relation between\n  the winding number and zero-energy edge states: The one-to-one relation between the winding number and the number of robust\nzero-energy edge states, known as bulk-boundary correspondence, is a celebrated\nfeature of 1d systems with chiral symmetry. Although this property can be\nexplained by the K-theory, the underlying mechanism remains elusive. Here, we\ndemonstrate that, even without resorting to advanced mathematical techniques,\none can prove this correspondence and clearly illustrate the mechanism using\nonly Cauchy's integral and elementary algebra. Furthermore, our approach to\nproving bulk-boundary correspondence also provides clear insights into a kind\nof system that doesn't respect chiral symmetry but can have robust left or\nright zero-energy edge states. In such systems, one can still assign the\nwinding number to characterize these zero-energy edge states."
    },
    {
        "anchor": "Accessing the transport properties of pristine few-layer black\n  phosphorus by van der Waals passivation in inert atmosphere: Ultrathin black phosphorus, or phosphorene, is the second known elementary\ntwo-dimensional material that can be exfoliated from a bulk van der Waals\ncrystal. Unlike graphene it is a semiconductor with a sizeable band gap and its\nexcellent electronic properties make it attractive for applications in\ntransistor, logic, and optoelectronic devices. However, it is also the first\nwidely investigated two dimensional electronic material to undergo degradation\nupon exposure to ambient air. Therefore a passivation method is required to\nstudy the intrinsic material properties, understand how oxidation affects the\nphysical transport properties and to enable future application of phosphorene.\nHere we demonstrate that atomically thin graphene and hexagonal boron nitride\ncrystals can be used for passivation of ultrathin black phosphorus. We report\nthat few-layer pristine black phosphorus channels passivated in an inert gas\nenvironment, without any prior exposure to air, exhibit greatly improved n-type\ncharge transport resulting in symmetric electron and hole trans-conductance\ncharacteristics. We attribute these results to the formation of oxygen acceptor\nstates in air-exposed samples which drastically perturb the band structure in\ncomparison to the pristine passivated black phosphorus.",
        "positive": "The Stokes-Einstein-Sutherland equation at the nanoscale revisited: The Stokes-Einstein-Sutherland (SES) equation is at the foundation of\nstatistical physics, relating a particle's diffusion coefficient and size with\nthe fluid viscosity, temperature and the boundary condition for the\nparticle-solvent interface. It is assumed that it relies on the separation of\nscales between the particle and the solvent, hence it is expected to break down\nfor diffusive transport on the molecular scale. This assumption is however\nchallenged by a number of experimental studies showing a remarkably small, if\nany, violation, while simulations systematically report the opposite. To\nunderstand these discrepancies, analytical ultracentrifugation experiments are\ncombined with molecular simulations, both performed at unprecedented\naccuracies, to study the transport of buckminsterfullerene C60 in toluene at\ninfinite dilution. This system is demonstrated to clearly violate the\nconditions of slow momentum relaxation. Yet, through a linear response to a\nconstant force, the SES equation can be recovered in the long time limit with\nno more than 4% uncertainty both in experiments and in simulations. This\nnonetheless requires partial slip on the particle interface, extracted\nconsistently from all the data. These results, thus, resolve a long-standing\ndiscussion on the validity and limits of the SES equation at the molecular\nscale."
    },
    {
        "anchor": "Irreducible and site symmetry induced representations of single/double\n  ordinary/gray layer groups: Considered are eighty sets of layer groups, each set consisted of four\ngroups: ordinary single and double, and gray single and double layer group.\nStructural properties of layer groups (factorization onto cyclic subgroups and\nexistence of grading according to the sequence of halving subgroups) enable\nefficient symbolic computation (by POLSym code) of the relevant properties,\nreal and complex irreducible and allowed (half-)integer (co-)representations in\nparticular. This task includes, as the first step, classification of the\nirreducible domains based on the group action in Brillouin zone combined with\ntorus topology. Also, the band (co-)representations induced from the\nirreducible (co-)representations of Wyckoff position stabilizers (site symmetry\ngroups) are decomposed onto the irreducible components. These, and other layer\ngroup symmetry related theoretical data relevant for physics, layered materials\nin particular, are tabulated and made available through the web site.",
        "positive": "Phase noise of self-sustained optomechanical oscillators: In this paper we present a theory that predicts the phase noise\ncharacteristics of self-sustained optomechanical oscillators. By treating the\ncavity optomechanical system as a feedback loop consisting of an optical cavity\nand a mechanical resonator, we analytically derive the transfer functions\nrelating the amplitude/phase noise of all the relevant dynamical quantities\nfrom the quantum Langevin equations, and obtain a closed-form expressions for\nthe phase noise spectral densities contributed from thermomechanical noise,\nphoton shot noise, and low-frequency technical laser noise. We numerically\ncalculate the phase noise for various situations and perform a sample\ncalculation for an experimentally demonstrated system. We also show that the\npresented model reduces to the well-known Leeson's phase noise model when the\namplitude noise and the amplitude/phase noise inter-transfers are ignored."
    },
    {
        "anchor": "Uniform e-beam irradiation-induced athermal straightening of axially\n  curved amorphous SiOx nanowire: The reshaping of amorphous SiOx nanowires (a-SiOx NWs) as purely induced by\nuniform electron beam (e-beam) irradiation was in-situ studied at room\ntemperature in transmission electron microscope. It was observed that the\naxially straight NW kept its perfect straight cylinder-like wire shape and\ndemonstrated a sequential uniform radial shrinkage with the increase of\nirradiation time. In contrast, the axially curved NW turned straight quickly\naccompanied with a uniform axial shrinkage and a uniform radial expansion\nintriguingly. It is expected that such a study especially on the straightening\nof axially curved NW has important implications for the nanoscale processing\nand stability of future NW-based structures or devices. More importantly, the\nfindings demonstrate that the traditional knock-on mechanism and electron beam\nheating effect are inadequate to explain these processes while our proposed\nnanocurvature effect and energetic beam-induced athermal activation effect\nobviously dominate the processes.",
        "positive": "Semiclassical theory of speckle correlations: Coherent wave propagation in random media results in a characteristic speckle\npattern, with spatial intensity correlations with short-range and long-range\nbehavior. Here, we show how the speckle correlation function can be obtained\nfrom a ray picture for two representative geometries: A chaotic cavity and a\nrandom waveguide. Our calculation allows us to study the crossover between a\n\"ray limit\" and a \"wave limit\", in which the Ehrenfest time $\\tau_E$ is larger\nor smaller than the typical transmission time $\\tau_D$, respectively.\nRemarkably, long-range speckle correlations persist in the ray limit $\\tau_E\n\\gg \\tau_D$."
    },
    {
        "anchor": "Graphene Conductivity near the Charge Neutral Point: Disordered Fermi-Dirac distributions are used to model, within a\nstraightforward and essentially phenomenological Boltzmann equation approach,\nthe electron/hole transport across graphene puddles. We establish, with\nstriking experimental support, a functional relationship between the graphene\nminimum conductivity, the mobility in the Boltzmann regime, and the steepness\nof the conductivity parabolic profile usually observed through gate-voltage\nscanning around the charge neutral point.",
        "positive": "Reducing disorder in graphene nanoribbons by chemical edge modification: We present electronic transport measurements on etched graphene nanoribbons\non silicon dioxide before and after a short hydrouoric acid (HF) treatment. We\nreport on changes in the transport properties, in particular, in terms of a\ndecreasing transport gap and a reduced doping level after HF dipping.\nInterestingly, the effective energy gap is nearly unaffected by the HF\ntreatment. Additional measurements on a graphene nanoribbon with lateral\ngraphene gates support strong indications that the HF significantly modifies\nthe edges of the investigated nanoribbons leading to a significantly reduced\ndisorder potential in these graphene nanostructures."
    },
    {
        "anchor": "Photonic spin Hall effect in Haldane materials: The photonic spin Hall effect of light beams reflected from the surfaces of\nvarious two-dimensional hexagonal crystalline structures, considering their\nassociated time-reversal $\\mathcal{T}$ and inversion $\\mathcal{I}$ symmetries,\nis investigated. Employing the Haldane model with tunable parameters as a\ngeneric model, we examine the longitudinal and transverse spin-separations of\nthe reflected beam in both topological non-trivial and trivial systems. The\nstudy reveals that the sign switching of the PSHE in these materials is\nattributed to the non-trivial and trivial topology. By manipulating the\ninterplay between spin-orbit coupling and external electric fields, we\ndemonstrate topological phase transitions in buckled Xene monolayer materials\nthrough the photonic spin Hall effect. Different behaviors of the photonic spin\nHall effect are observed in various topological phases within these materials.\nAdditionally, we explore the reflected spin and valley-polarized spatial shifts\nin monolayer transition metal dichalcogenides. The photonic spin Hall effect in\nbuckled Xene monolayer materials and transition metal dichalcogenides is highly\ninfluenced by the spin and valley degrees of freedom of charge carriers,\noffering a promising avenue to explore spintronics and valleytronics in these\nhexagonal materials. We propose that the photonic spin Hall effect in Haldane\nmaterials can serve as a metrological tool for optical parameter\ncharacterization and as a promising method for determining Chern numbers and\ntopological phase transitions through direct optical weak measurement\ntechniques.",
        "positive": "Visualizing the Localized Electrons of a Kagome Flat Band: Destructive interference between electron wavefunctions on the\ntwo-dimensional (2D) kagome lattice induces an electronic flat band, which\ncould host a variety of interesting many-body quantum states. Key to realize\nthese proposals is to demonstrate the real space localization of kagome flat\nband electrons. In particular, the extent to which the often more complex\nlattice structure and orbital composition of realistic materials counteract the\nlocalizing effect of destructive interference, described by the 2D kagome\nlattice model, is hitherto unknown. We used scanning tunneling microscopy (STM)\nto visualize the non-trivial Wannier states of a kagome flat band at the\nsurface of CoSn, a kagome metal. We find that the local density of states\nassociated with the flat bands of CoSn is localized at the center of the kagome\nlattice, consistent with theoretical expectations for their corresponding\nWannier states. Our results show that these states exhibit an extremely small\nlocalization length of two to three angstroms concomitant with a strongly\nrenormalized quasiparticle velocity, which is comparable to that of moir\\'e\nsuperlattices. Hence, interaction effects in the flat bands of CoSn could be\nmuch more significant than previously thought. Our findings provide fundamental\ninsight into the electronic properties of kagome metals and are a key step for\nfuture research on emergent many-body states in transition metal based kagome\nmaterials."
    },
    {
        "anchor": "High rectifying performance of heterojunctions with interface between\n  armchair C$_3$N nanoribbons with and without edge H-passivation: Two-dimensional polyaniline with C$_3$N stoichiometry, is a newly fabricated\nlayered material that has been expected to possess fascinating electronic,\nthermal, mechanical and chemical properties. The nature of its counterpart\nnano-ribbons/structures offering even more tunability in property because of\nthe unique quantum confinement and edge effect, however, has not been revealed\nsufficiently. Here, using the first-principles calculation based on density\nfunctional theory and nonequilibrium Green's function technique, we first\nperform a study on the electron band structure of armchair C$_3$N nanoribbons\n(AC$_3$NNRs) without and with H-passivation. The calculated results show that\nthe pristine AC$_3$NNRs are metal, while the H-passivated ones are either\ndirect or indirect band gap semiconductors depending on the detailed edge\natomic configurations. Then we propose a lateral planar homogenous junction\nwith an interface between the pristine and H-passivated AC$_3$NNRs, in which\nforms a Schottky-like barrier. Interestingly, our further transport calculation\ndemonstrates that this AC$_3$NNRs-based heterojunction exhibits a good\nrectification behavior. In specification, the average rectification ratio (RR)\ncan reach up to $10^3$ in the bias regime from 0.2 to 0.4 V. Particularly,\nextending the length of semiconductor part in the heterojunction leads to the\ndecrease of the current through the junction, but the RR can be enlarged\nobviously. The average RR increases to the order of $10^4$ in the bias from\n0.25 to 0.40 V, with the boosted maximum up to $10^5$ at 0.35 V. The findings\nof this work may be serviceable for the design of functional nanodevices based\non AC$_3$NNRs in the future.",
        "positive": "Generation of non-classical photon states in superconducting quantum\n  metamaterials: We report a theoretical study of diverse non-classical photon states that can\nbe realized in superconducting quantum metamaterials. As a particular example\nof superconducting quantum metamaterials an array of SQUIDs incorporated in a\nlow-dissipative transmission line (resonant cavity) will be studied. This\nsystem will be modeled as a set of two-levels systems (qubits) strongly\ninteracting with resonant cavity photons. We predict and analyze {a\nsecond(first)-order phase transition} between an incoherent (the\nhigh-temperature phase) and coherent (the low-temperatures phase) states of\nphotons. In equilibrium state the partition function $Z$ of the electromagnetic\nfield (EF) in the cavity is determined by the effective action\n$S_{eff}\\{P(\\tau)\\}$ that, in turn, depends on imaginary-time dependent\nmomentum of photon field $P(\\tau)$. We show that the order parameter of this\nphase transition is the $P_{0}(\\tau)$ minimizing the effective action of a\nwhole system. In the incoherent state the order parameter $P_{0}(\\tau)=0$ but\nat low temperatures we obtain various coherent states characterized by non-zero\nvalues of $P_{0}(\\tau)$. This phase transition in many aspects resembles the\nPeierls metal-insulator and the metal-superconductor phase transitions. The\ncritical temperature of such phase transition $T^\\star$ is determined by the\nenergy splitting of two-level systems $\\Delta$, a number of SQUIDs in the array\n$N$, and the strength of the interaction $\\eta$ between SQUIDs and photons in\ncavity."
    },
    {
        "anchor": "Theoretical aspects of quantum state transfer, correlation measurement\n  and electron-nuclei coupled dynamics in quantum dots: Photons and electrons are the key quantum media for the quantum information\nprocessing based on solid state devices. The essential ingredients to\naccomplish the quantum repeater were investigated and their underlying physics\nwere revealed. The relevant elementary processes of the quantum state transfer\nbetween a single photon and a single electron were analyzed, to clarify the\nconditions to be satisfied to achieve the high fidelity of the quantum state\ntransfer. An optical method based on the Faraday rotation was proposed to carry\nout the Bell measurement of two electrons which is a key operation in the\nentanglement swapping for the quantum repeater and its feasibility was\nconfirmed. Also investigated was the quantum dynamics in the electron-nuclei\ncoupled spin system in quantum dots and a couple of new phenomena were\npredicted related to the correlations induced by the hyperfine interaction,\nnamely, bunching and revival in the electron spin measurements. These findings\nwill pave the way to accomplish the efficient and robust quantum repeater and\nnuclear spin quantum memory.",
        "positive": "Gate Tunable Lateral 2D pn Junctions: An Analytical Study of Its\n  Electrostatics: The electrostatics of two-dimensional (2D) lateral pn homojunctions\nconsidering the impact of electrostatic doping by means of two split\nbottom-gates are studied here. Analytical expressions are obtained from the\nsolution of the 2D Poisson equation considering a depletion approximation.\nStraightforward analytical models for the electrostatic potential and the\ndepletion width within both the dielectric and the 2D semiconductor are\nobtained for both the symmetrical and asymmetrical cases. In contrast to the\ncase of devices with chemical doping, the obtained depletion width model of\ndevices with electrostatic doping do not depend on the dielectric constant but\nonly on the electrostatic potential and oxide thickness. The models describe\nthe electrostatics of gate-tunable 2D pn junctions at arbitrary bias. A\nbenchmark against numerical device simulations of MoS2-based pn junctions\nvalidate the analytical models."
    },
    {
        "anchor": "Triplet excitation and electroluminescence from a supramolecular\n  monolayer embedded in a boron nitride tunnel barrier: We show that ordered monolayers of organic molecules stabilized by hydrogen\nbonding on the surface of exfoliated few-layer hexagonal boron nitride (hBN)\nflakes may be incorporated into van der Waals heterostructures with integral\nfew-layer graphene contacts forming a molecular/2D hybrid tunneling diode.\nElectrons can tunnel from through the hBN/molecular barrier under an applied\nvoltage VSD and we observe molecular electroluminescence from an excited\nsinglet state with an emitted photon energy > eVSD, indicating up-conversion by\nenergies up to ~ 1 eV. We show that tunnelling electrons excite embedded\nmolecules into singlet states in a two-step process via an intermediate triplet\nstate through inelastic scattering and also observe direct emission from the\ntriplet state. These heterostructures provide a solid-state device in which\nspin-triplet states, which cannot be generated by optical transitions, can be\ncontrollably excited and provide a new route to investigate the physics,\nchemistry and quantum spin-based applications of triplet generation, emission\nand molecular photon up-conversion.",
        "positive": "Hopping conductivity in the quantum Hall effect -- revival of universal\n  scaling: We have measured the temperature dependence of the conductivity $\\sigma_{xx}$\nof a two-dimensional electron system deep into the localized regime of the\nquantum Hall plateau transition. Using variable-range hopping theory we are\nable to extract directly the localization length $\\xi$ from this experiment. We\nuse our results to study the scaling behavior of $\\xi$ as a function of the\nfilling factor distance $|\\delta \\nu|$ to the critical point of the transition.\nWe find for all samples a power-law behavior $\\xi\\propto|\\delta\\nu|^{-\\gamma}$\nwith a universal scaling exponent $\\gamma = 2.3$ as proposed theoretically."
    },
    {
        "anchor": "On the effect of weak disorder on the density of states in graphene: The effect of weak potential and bond disorder on the density of states of\ngraphene is studied. By comparing the self-consistent non-crossing\napproximation on the honeycomb lattice with perturbation theory on the Dirac\nfermions, we conclude, that the linear density of states of pure graphene\nchanges to a non-universal power-law, whose exponent depends on the strength of\ndisorder like 1-4g/sqrt{3}t^2\\pi, with g the variance of the Gaussian disorder,\nt the hopping integral. This can result in a significant suppression of the\nexponent of the density of states in the weak-disorder limit. We argue, that\neven a non-linear density of states can result in a conductivity being\nproportional to the number of charge carriers, in accordance with experimental\nfindings.",
        "positive": "Graphene in periodic deformation fields: dielectric screening and\n  plasmons: We consider the effect of periodic scalar and vector potentials generated by\nperiodic deformations of the graphene crystal lattice, on the energy spectrum\nof electrons. The dependence of electron velocity near the Dirac point on the\nperiodic perturbations of different types is discussed. We also investigated\nthe effect of screening of the scalar potential by calculating the dielectric\nfunction as a function of the wave length of the periodic potential. This\ncalculation shows that the periodic scalar field is strongly suppressed by the\nscreening. Using the dependence of electron velocity on the periodic field we\nalso studied the variation of the plasmon spectra in graphene. We found that\nthe spectrum of plasmon excitations can be effectively controlled by the\nperiodic strain field."
    },
    {
        "anchor": "Conductance properties of nanotubes coupled to superconducting leads:\n  signatures of Andreev states dynamics: We present a combined experimental and theoretical analysis of the low bias\nconductance properties of carbon nanotubes coupled to superconducting leads. In\nthe Kondo regime the conductance exhibits a zero bias peak which can be several\ntimes larger than the unitary limit in the normal case. This zero bias peak can\nbe understood by analyzing the dynamics of the subgap Andreev states under an\napplied bias voltage. It is shown that the existence of a linear regime is\nlinked to the presence of a finite relaxation rate within the system. The\ntheory provides a good fitting of the experimental results.",
        "positive": "Quantum-dot circuit-QED thermoelectric diodes and transistors: Recent breakthroughs in quantum-dot circuit-quantum-electrodynamics\n(circuit-QED) systems are important both from a fundamental perspective and\nfrom the point of view of quantum photonic devices. However, understanding the\napplications of such setups as potential thermoelectric diodes and transistors\nhas been missing. In this paper, via the Keldysh nonequilibrium Green's\nfunction approach, we show that cavity-coupled double quantum-dots can serve as\nexcellent quantum thermoelectric diodes and transistors. Using an enhanced\nperturbation approach based on polaron-transformations, we find non-monotonic\ndependences of thermoelectric transport properties on the electron-photon\ninteraction. Strong light-matter interaction leads to pronounced rectification\neffects for both charge and heat, as well as thermal transistor effects in the\nlinear transport regime, which opens up a cutting-edge frontier for quantum\nthermoelectric devices."
    },
    {
        "anchor": "Sequential electron transport and vibrational excitations in an organic\n  molecule coupled to few-kayer graphene electrodes: Graphene electrodes are promising candidates to improve reproducibility and\nstability in molecular electronics through new electrode-molecule anchoring\nstrategies. Here we report sequential electron transport in few-layer graphene\ntransistors containing individual curcuminoid-based molecules anchored to the\nelectrodes via pi-pi orbital bonding. We show the coexistence of inelastic\nco-tunneling excitations with single-electron transport physics owing to an\nintermediate molecule-electrode coupling; we argue that an intermediate\nelectron-phonon coupling is the origin of these vibrational-assisted\nexcitations. These experimental observations are complemented with density\nfunctional theory calculations to model electron transport and the interaction\nbetween electrons and vibrational modes of the curcuminoid molecule. We find\nthat the calculated vibrational modes of the molecule are in agreement with the\nexperimentally observed excitations.",
        "positive": "Long-Range Orbital Magnetoelectric Torque in Ferromagnets: While it is often assumed that the orbital response is suppressed and\nshort-ranged due to strong crystal field potential and orbital quenching, we\nshow that the orbital magnetoelectric response can be remarkably long-ranged in\nferromagnets. In a bilayer consisting of a nonmagnet and a ferromagnet, spin\ninjection from the interface results in spin accumulation and torque in the\nferromagnet, which rapidly oscillate and decay by spin dephasing. In contrast,\nwe find that even when an external electric field is applied only on the\nnonmagnet, we find substantially long-ranged orbital magnetoelectric response\nin the FM, which can go far beyond the spin dephasing length. This unusual\nfeature is attributed to nearly degenerate orbital characters imposed by the\ncrystal symmetry, which form hotspots for the intrinsic orbital response.\nBecause only the states near the hotspots contribute dominantly, the induced\norbital angular momentum does not exhibit destructive interference among states\nwith different momentum as in the case of the spin dephasing. This gives rise\nto a distinct type of orbital torque on the magnetization, increasing with the\nthickness of the ferromagnet. Such behavior may serve as critical long-sought\nevidence of orbital transport to be directly tested in experiments. Our\nfindings open the possibility of using long-range orbital magnetoelectric\neffect in orbitronic device applications."
    },
    {
        "anchor": "Majorana-magnon interactions in topological Shiba chains: A chain of magnetic impurities deposited on the surface of a superconductor\ncan form a topological Shiba band that supports Majorana zero modes and holds a\npromise for topological quantum computing. Yet, most experiments scrutinizing\nthese zero modes rely on transport measurements, which only capture local\nproperties. Here we propose to leverage the intrinsic dynamics of the magnetic\nimpurities to access their non-local character. We use linear response theory\nto determine the dynamics of the uniform magnonic mode in the presence of\nexternal $ac$ magnetic fields and coupling the Shiba electrons. We demonstrate\nthat this mode, which spreads over the entire chain of atoms, becomes imprinted\nwith the parity of the ground state and, moreover, can discriminate between\nMajorana and trivial zero modes located at the ends of the chain. Our approach\noffers a non-invasive alternative to the scanning tunneling microscopy\ntechniques used to probe Majorana zero modes. Conversely, the magnons could\nfacilitate the manipulation of Majorana zero modes in topological Shiba chains.",
        "positive": "Quasi-bound states and continuum absorption background of polar\n  Al0.5Ga0.5N/GaN quantum dots: A theoretical interpretation of the photoluminescence excitation spectra of\nself-organized polar GaN/(Al,Ga)N quantum dots is proposed. A numerical method\nassuming a realistic shape of the dots and including the built-in electric\nfield effects is developed to calculate their energy structure and hence their\noptical absorption. The electron and hole spectra show the existence of a set\nof quasi-bound states that does not originate from the wetting layer, and plays\na crucial role in the observed absorption spectrum of the GaN/(Al,Ga)N dots.\nTransitions involving these quasi-bound states and wetting layer states give a\nsufficient explanation for the observed continuum absorption background. The\nproperties of this absorption band, especially its extension, depend strongly\non the dot's size. Our simulation provides a natural explanation of the\nexperimental luminescence excitation spectra of ensembles of dots of different\nheights. Our theoretical model can be extended to cases where the confinement\npotentials are complicated by the presence of a stronger electric field."
    },
    {
        "anchor": "Manipulating the Topology of Nanoscale Skyrmion Bubbles by Spatially\n  Geometric Confinement: The discovery of magnetic skyrmion bubbles in centrosymmetric magnets has\nbeen receiving increasing interest from the research community, due to the\nfascinating physics of topological spin textures and its possible applications\nto spintronics. However, key challenges remain, such as how to manipulate the\nnucleation of skyrmion bubbles to exclude the trivial bubbles or metastable\nskyrmion bubbles that usually coexist with skyrmion bubbles in the\ncentrosymmetric magnets. Here, we report having successfully performed this\ntask by applying spatially geometric confinement to a centrosymmetric\nfrustrated Fe3Sn2 magnet. We demonstrate that the spatially geometric\nconfinement can indeed stabilize the skyrmion bubbles, by effectively\nsuppressing the formation of trivial bubbles and metastable skyrmion bubbles.\nWe also show that the critical magnetic field for the nucleation of the\nskyrmion bubbles in the confined Fe3Sn2 nanostripes is drastically less, by an\norder of magnitude, than that what is required in the thin plate without\ngeometrical confinement. By analyzing how the width and thickness of the\nnanostripes affect the spin textures of skyrmion bubbles, we infer that the\ntopological transition of skyrmion bubbles is closely related to the\ndipole-dipole interaction, which we find is consistent with theoretical\nsimulations. The results presented here represent an important step forward in\nmanipulating the topological spin textures of skyrmion bubbles, making us\ncloser to achieving the fabrication of skyrmion-based racetrack memory devices.",
        "positive": "The emergence, coalescence and topological properties of multiple\n  exceptional points and their experimental realization: Non-Hermitian systems distinguish themselves from Hermitian systems by\nexhibiting a phase transition point called an exceptional point (EP), which is\nthe point at which two eigenstates coalesce under a system parameter variation.\nMany interesting EP phenomena such as level crossings/repulsions in\nnuclear/molecular and condensed matter physics, and unusual phenomena in optics\nsuch as loss-induced lasing and unidirectional transmission can be understood\nby considering a simple 2x2 non-Hermitian matrix. At a higher dimension, more\ncomplex EP physics not found in two-state systems arises. We consider the\nemergence and interaction of multiple EPs in a four-state system theoretically\nand realize the system experimentally using four coupled acoustic cavities with\nasymmetric losses. We find that multiple EPs can emerge and as the system\nparameters vary, these EPs can collide and merge, leading to higher order\nsingularities and topological characteristics much richer than those seen in\ntwo-state systems."
    },
    {
        "anchor": "Charge conservation protected topological phases: We discuss the relation between particle number conservation and topological\nphases. In four spatial dimensions, we find that systems belonging to different\ntopological phases in the presence of a U(1) charge conservation can be\nconnected adiabatically, i.e., without closing the gap, upon intermediately\nbreaking this local symmetry by a superconducting term. The time reversal\npreserving topological insulator states in 2D and 3D which can be obtained from\nthe 4D parent state by dimensional reduction inherit this protection by charge\nconservation. Hence, all topological insulators can be adiabatically connected\nto a trivial insulating state without breaking time reversal symmetry, provided\nan intermediate superconducting term is allowed during the adiabatic\ndeformation. Conversely, in one spatial dimension, non-symmetry-protected\ntopological phases occur only in systems that break U(1) charge conservation.\nThese results can intuitively be understood by considering a natural embedding\nof the classifying spaces of charge conserving Hamiltonians into the\ncorresponding Bogoliubov de Gennes classes.",
        "positive": "Spin precession in a fractional quantum Hall state with spin-orbit\n  coupling: Experimental attempts to realize spin-devices based on concepts derived from\nsingle-particle theoretical approaches have not been very successful yet. This\nraises the fundamental question of whether inter-electron interactions can be\nneglected in planar electron-based spintronics devices. We report on our\nresults of a many-body approach to the spin configuration in a quantum Hall\nstate in the presence of Bychkov-Rashba type spin-orbit interaction. While some\nproperties of this system are found to be ideally suited for exploitation in\nspin devices, others might seem to limit its applicability. The latter can\nhowever be optimized for device performance."
    },
    {
        "anchor": "Self-Diffusion and Structure of a Quasi Two-Dimensional, Classical\n  Coulomb Gas Under Increasing Magnetic Field and Temperature: The influence of a magnetic field applied perpendicularly to the plane of a\nquasi two dimensional, low density classical Coulomb gas, with interparticle\npotential U of r as 1 over r, is studied using momentum conserving dissipative\nparticle dynamics simulations. The self diffusion and structure of the gas are\nstudied as functions of temperature and strength of the magnetic field. It is\nfound that the gas undergoes a topological phase transition when the\ntemperature is varied, in accord with the Bohr van Leeuwen BvL theorem, the\nstructural properties being unaffected, resembling those of the strictly two\ndimensional Kosterlitz Thouless transition, with U of r as varying as ln r.\nConsistent with the BvL theorem, the transition temperature and the melting\nprocess of the condensed phase are unchanged by the field. Conversely, the self\ndiffusion coefficient of the gas is strongly reduced by the magnetic field. At\nthe largest values of the cyclotron frequency, the self diffusion coefficient\nis inversely proportional to the applied magnetic field. The implications of\nthese results are discussed.",
        "positive": "Nonlinear effects for three-terminal heat engine and refrigerator: The three-terminal heat device consisting of a cavity and coupled to a heat\nbath is established. By tuning the temperatures of the electrodes and the\nphonon bath, the device can function as a heat engine or a refrigerator. We\nstudy the characteristic performance in the linear and nonlinear regime for\nboth setups. It is our focus here to analyze how the efficiency of the heat\nengine and coefficient of performance of the refrigerator are affected by the\nnonlinear transport. With such considerations, the maximum efficiency and power\nare then optimized for various energy levels, temperatures and other\nparameters."
    },
    {
        "anchor": "A simple model potential for hollow nanospheres: A new model potential is introduced to describe the hollow nanospheres such\nas fullerene and molecular structures and to obtain their electronic\nproperties. A closed analytical solution of the corresponding treatment is\ngiven within the framework of supersymmetric perturbation theory.",
        "positive": "System analysis of Force Feedback Microscopy: It was shown recently that the Force Feedback Microscope can avoid the\njump-to-contact in Atomic force Microscopy even when the cantilevers used are\nvery soft, thus increasing force resolution. In this letter, we explore\ntheoretical aspects of the associated real time control of the tip position. We\ntake into account lever parameters such as the lever characteristics in its\nenvironment, spring constant, mass, dissipation coefficient and the operating\nconditions such as controller gains, and interaction force. We show how the\ncontroller parameters are determined so that the FFM functions at its best and\nestimate the bandwidth of the system under these conditions."
    },
    {
        "anchor": "Kinetics of 4He gas sorption by fullerite C60. Quantum effects: The kinetics of helium gas sorption by a C60 powder and subsequent desorption\nof the 4He impurity from the saturated powder has been investigated in the\ntemperature interval T = 2-292 K. Evidence is obtained that supports the\nexistence of two stages in the temperature dependences of sorption and\ndesorption. The stages account for the different times taken by helium to\noccupy the octahedral and tetrahedral interstices in the C60 lattice. The\ncharacteristic times of sorption and desorption coincide. It is found that the\ntemperature dependences of the characteristic times of occupying the octahedral\nand tetrahedral interstices are nonmonotonic. As the temperature is lowered\nfrom 292 K to 79.3 K, the characteristic times increase, which indicates a\npredominance of thermally activated diffusion of helium in C60. On a further\ndecrease to T = 10 K the characteristic times reduce over an order of\nmagnitude. Below 8 K the characteristic times of sorption and desorption are\ntemperature-independent. This suggests a tunnel character of 4He diffusion in\nC60.",
        "positive": "Transport in line junctions of $\u03bd=5/2$ quantum Hall liquids: We calculate the tunneling current through long line junctions of a $\\nu=5/2$\nquantum Hall liquid and i) another $\\nu=5/2$ liquid, ii) an integer quantum\nHall liquid and iii) a quantum wire. Momentum resolved tunneling provides\ninformation about the number, propagation directions and other features of the\nedge modes and thus helps distinguish several competing models of the 5/2\nstate. We investigate transport properties of two proposed Abelian states: $K=8\nstate and 331 state, and four possible non-Abelian states: Pfaffian,\nedge-reconstructed Pfaffian, and two versions of the anti-Pfaffian state. We\nalso show that the non-equilibrated anti-Pfaffian state has a different\nresistance from other proposed states in the bar geometry."
    },
    {
        "anchor": "Magnetic Droplet Soliton Nucleation in Oblique Fields: We study the auto-oscillating magnetodynamics in orthogonal spin torque\nnano-oscillators (STNOs) as a function of the out-of-plane (OOP) magnetic field\nangle. In perpendicular fields and at OOP field angles down to approximately 50\ndegrees we observe the nucleation of a droplet. However, for field angles below\n50 degrees, experiments indicate that the droplet gives way to propagating spin\nwaves, in agreement with our micromagnetic simulations. Theoretical\ncalculations show that the physical mechanism behind these observations is the\nsign changing of spin-wave nonlinearity (SWN) by angle. In addition, we show\nthat the presence of a strong perpendicular magnetic anisotropy (PMA) free\nlayer in the system reverses the angular dependence of the SWN and dynamics in\nSTNOs with respect to the known behavior determined for the in-plane magnetic\nanisotropy free layer. Our results are of fundamental interest in understanding\nthe rich dynamics of nanoscale solitons and spin-wave dynamics in STNOs.",
        "positive": "Transverse Shift in Andreev Reflection: An incoming electron is reflected back as a hole at a\nnormal-metal-superconductor interface, a process known as Andreev reflection.\nWe predict that there exists a universal transverse shift in this process due\nto the effect of spin-orbit coupling in the normal metal. Particularly, using\nboth the scattering approach and the argument of angular momentum conservation,\nwe demonstrate that the shifts are pronounced for lightly-doped Weyl\nsemimetals, and are opposite for incoming electrons with different chirality,\ngenerating a chirality-dependent Hall effect for the reflected holes. The\npredicted shift is not limited to Weyl systems, but exists for a general\nthree-dimensional spin-orbit- coupled metal interfaced with a superconductor."
    },
    {
        "anchor": "Statistical Topological Insulators: We define a class of insulators with gapless surface states protected from\nlocalization due to the statistical properties of a disordered ensemble, namely\ndue to the ensemble's invariance under a certain symmetry. We show that these\ninsulators are topological, and are protected by a $\\mathbb{Z}_2$ invariant.\nFinally, we prove that every topological insulator gives rise to an infinite\nnumber of classes of statistical topological insulators in higher dimensions.\nOur conclusions are confirmed by numerical simulations.",
        "positive": "Polarization dependence of the two-photon Franz-Keldysh effect: The effect of a constant electric field on two-photon absorption in a direct\nband gap semiconductor is calculated using an independent-particle theory. Two\nband structure models for GaAs are used: a two-band parabolic model and an\neight-band \"k dot p\" model. Both predict a strong dependence of the two-photon\nelectroabsorption spectrum on the polarization of the light with respect to the\nconstant field. We attribute the polarization dependence to the strong effect\nof a constant field on intraband dynamics."
    },
    {
        "anchor": "Impurity scattering and Friedel oscillations in mono-layer black\n  phosphorus: We study the effect of impurity scattering effect in black phosphorurene (BP)\nin this work. For single impurity, we calculate impurity induced local density\nof states (LDOS) in momentum space numerically based on tight-binding\nHamiltonian. In real space, we calculate LDOS and Friedel oscillation\nanalytically. LDOS shows strong anisotropy in BP. Many impurities in BP are\ninvestigated using $T$-matrix approximation when the density is low. Midgap\nstates appear in band gap with peaks in DOS. The peaks of midgap states are\ndependent on impurity potential. For finite positive potential, the impurity\ntends to bind negative charge carriers and vise versa. The infinite impurity\npotential problem is related to chiral symmetry in BP.",
        "positive": "Finite frequency current fluctuations and the self-consistent\n  perturbation theory for electron transport through quantum dot: We have formulated the problem of electron transport through interacting\nquantum dot system in the framework of self-consistent perturbation theory, and\nshow that the current conservation condition is guaranteed due to the gauge\ninvariant properties of the Green's functions and the generalized Ward\nidentity. By using a generating functional for the statistics of the\nnonequilibrium system, we have obtained general formulae for calculating the\ncurrent and the current fluctuations in the presence of arbitrary\ntime-dependent potentials. As demonstration of application, we have studied the\ninteraction effects on the finite frequency noise for electron resonant\ntunneling through an Anderson impurity, and obtained an analytical equation for\nthe interaction effect on the finite frequency current noise within the Hartree\napproximation, which is an extension of the previous results obtained by\nHershfield on zero frequency shot noise."
    },
    {
        "anchor": "Spin and charge pumping by steady or pulse current-driven magnetic\n  domain wall: A self-consistent multiscale\n  time-dependent-quantum/time-dependent-classical approach: We introduce a multiscale framework which combines time-dependent\nnonequilibrium Green function (TD-NEGF) algorithms, scaling linearly in the\nnumber of time steps and describing quantum-mechanically conduction electrons\nin the presence of time-dependent fields of arbitrary strength or frequency,\nwith classical time evolution of localized magnetic moments described by the\nLandau-Lifshitz-Gilbert (LLG) equation. The TD-NEGF+LLG framework can be\napplied to a variety of problems where current-driven spin torque induces\ndynamics of magnetic moments as the key resource for next generation\nspintronics. Using magnetic domain wall (DW) as an example, we predict that its\nmotion will pump time-dependent spin and charge currents (on the top of\nunpolarized DC charge current injected through normal metal leads to drive the\nDW motion). The conversion of AC components of spin current, whose amplitude\nincreases (decreases) as the DW approaches (distances from) the normal metal\nlead, into AC voltage via the inverse spin Hall effect offers a tool to\nprecisely track the DW position along magnetic nanowire. We also quantify the\nDW transient inertial displacement due to its acceleration and deceleration by\npulse current and the entailed spin and charge pumping. Finally, TD-NEGF+LLG as\na nonperturbative (i.e., numerically exact) framework allows us to establish\nthe limits of validity of the so-called spin-motive force (SMF) theory for\npumped charge current by time-dependent magnetic textures---the perturbative\nanalytical formula of SMF theory becomes inapplicable for large frequencies\n(but unrealistic in magnetic system) and, more importantly, for increasing\nnoncollinearity when the angles between neighboring magnetic moments exceed\n$\\simeq 10^\\circ$.",
        "positive": "Spin transport of electrons and holes in a metal and in a semiconductor: The features of the spin and charge transport of electrons and holes in a\nmetal and a semiconductor were studied using the Boltzmann transport equations.\nIt was shown that the electrons and holes carry the spin in opposite directions\nin an electrical current. As result, the spin polarization of an electrical\ncurrent in a metal is substantially smaller than spin polarization of electron\ngas. It was shown that the spin properties of the electron gas are responsible\nfor the existence of the concept of \"electrons\" and \"holes\" in a metal and a\nsemiconductor."
    },
    {
        "anchor": "Kane-Mele with a twist: Quasicrystalline higher-order topological\n  insulators with fractional mass kinks: We establish an analytic low-energy theory describing higher-order\ntopological insulator (HOTI) phases in quasicrystalline systems. We apply this\nto a model consisting of two stacked Haldane models with oppositely propagating\nedge modes, analogous to the Kane-Mele model, and with a $30^\\circ$ twist. We\nshow that the resulting localized modes at corners, characteristic of a HOTI,\nare not associated with conventional mass inversions but are instead associated\nwith what we dub \"fractional mass kinks\". By generalizing the low-energy\ntheory, we establish a classification for arbitrary $ n $-fold rotational\nsymmetries. We also derive a relationship between corner modes in a bilayer and\ndisclination modes in a single layer. By using numerics to go beyond the\nweak-coupling limit, we show that a hierarchy of additional gaps occurs due to\nthe quasiperiodicity, which also harbor corner-localized modes.",
        "positive": "Intrinsic antiferromagnetic topological insulator and axion state in\n  V2WS4: Intrinsic magnetic topological insulators offers an ideal platform to explore\nexotic topological phenomena, such as axion electrodynamics, quantum anomalous\nHall (QAH) effect and Majorana edge modes. However, these emerging new physical\neffects have rarely been experimentally observed due to the limited choice of\nsuitable materials. Here, we predict the van der Waals layered V$_2$WS$_4$ and\nits related materials show intralayer ferromagnetic and interlayer\nantiferromagnetic exchange interactions. We find extremely rich magnetic\ntopological states in V$_2$WS$_4$, including an antiferromagnetic topological\ninsulator, the axion state with the long-sought quantized topological\nmagnetoelectric effect, three-dimensional QAH state, as well as a collection of\nQAH insulators and intrinsic axion insulators in odd- and even-layer films,\nrespectively. Remarkably, the N\\'eel temperature of V$_2$WS$_4$ is predicted to\nbe much higher than that of MnBi$_2$Te$_4$. These interesting predictions, if\nrealized experimentally, could greatly promote the topological quantum physics\nresearch and application."
    },
    {
        "anchor": "Gate-Defined Quantum Dots on Carbon Nanotubes: We report the realization of nanotube-based quantum dot structures that use\nlocal electrostatic gating to produce individually controllable dots in series\nalong a nanotube. Electrostatic top-gates produce depletion regions in the\nunderlying tube; a pair of such depletion regions defines a quantum dot.\nTransparencies of tunnel barriers as well as the electrostatic energies, within\nsingle and multiple dots, can be tuned by gate voltages. The approach allows\naccurate control over multiple devices on a single tube, and serves as a design\nparadigm for nanotube-based electronics and quantum systems.",
        "positive": "Nonequilibrium dynamics of spontaneous symmetry breaking into a hidden\n  state of charge-density wave: Nonequilibrium phase transition plays a pivotal role in a broad physical\ncontext from condensed matter to cosmology. Tracking the formation of\nnon-equilibrium phases in condensed matter is challenging and requires a\nresolution of the long-range cooperativity on ultra-short timescales. Here, we\nstudy the spontaneous symmetry breaking transformation of a charge-density wave\nsystem from a stripe phase into a checkerboard state. Such a state is\nthermodynamically forbidden, but is introduced through a system quench using\nultrashort, intense laser pulses. The dynamics is mediated by the soft modes\nthat unfold spontaneously and order the field on a timescale ~1 ps. Using the\ncoherent electron diffraction with ~100 fs resolution, we capture the entire\ncourse and demonstrate nonergodic behavior proximal to symmetry breaking that\nis crucial for stabilizing the hidden states. Remarkably, the thermalization\ndue to carriers cooling arrests the remnants of the transient orders into the\ntopological defects in the eventual state with distinct new properties that\nlast for more than 1 ns. The fundamental dynamics observed here opens an\nintriguing perspective of controlling phase transitions in quantum materials\nfar from equilibrium."
    },
    {
        "anchor": "Charge accumulation at the boundaries of a graphene strip induced by a\n  gate voltage: Electrostatic approach: Distribution of charge induced by a gate voltage in a graphene strip is\ninvestigated. We calculate analytically the charge profile and demonstrate a\nstrong(macroscopic) charge accumulation along the boundaries of a\nmicrometers-wide strip. This charge inhomogeneity is especially important in\nthe quantum Hall regime where we predict the doubling of the number of edge\nstates and coexistence of two different types of such states. Applications to\ngraphene-based nanoelectronics are discussed.",
        "positive": "Time-reversal invariant finite-size topology: We report finite-size topology in the quintessential time-reversal (TR)\ninvariant systems, the quantum spin Hall insulator (QSHI) and the\nthree-dimensional, strong topological insulator (STI): previously-identified\nhelical or Dirac cone boundary states of these phases hybridize in wire or slab\ngeometries with one open boundary condition for finite system size, and\nadditional, topologically-protected, lower-dimensional boundary modes appear\nfor open boundary conditions in two or more directions. For the\nquasi-one-dimensional (q(2-1)D) QSHI, we find topologically-protected,\nquasi-zero-dimensional (q(2-2)D) boundary states within the hybridization gap\nof the helical edge states, determined from q(2-1)D bulk topology characterized\nby topologically non-trivial Wilson loop spectra. We show this finite-size\ntopology furthermore occurs in 1T'-WTe2 in ribbon geometries with sawtooth\nedges, based on analysis of a tight-binding model derived from\ndensity-functional theory calculations, motivating experimental investigation\nof our results. In addition, we find quasi-two-dimensional (q(3-1)D)\nfinite-size topological phases occur for the STI, yielding helical boundary\nmodes distinguished from those of the QSHI by a non-trivial magneto-electric\npolarizability linked to the original 3D bulk STI. Finite-size topological\nphases therefore exhibit signatures associated with the non-trivial topological\ninvariant of a higher-dimensional bulk. Finally, we find the q(3-2)D STI also\nexhibits finite-size topological phases, finding the first signs of\ntopologically-protected boundary modes of codimension greater than 1 due to\nfinite-size topology. Finite-size topology of four or higher-dimensional\nsystems is therefore possible in experimental settings without recourse to\nthermodynamically large synthetic dimensions."
    },
    {
        "anchor": "Observation of highly dispersive bands in pure thin film C$_{60}$: While long-theorized, the direct observation of multiple highly dispersive\nC$_{60}$ valence bands has eluded researchers for more than two decades due to\na variety of intrinsic and extrinsic factors. Here we report a realization of\nmultiple highly dispersive (330-520 meV) valence bands in pure thin film\nC$_{60}$ on a novel substrate--the three-dimensional topological insulator\nBi$_{2}$Se$_{3}$--through the use of angle-resolved photoemission spectroscopy\n(ARPES) and first-principles calculations. The effects of this novel substrate\nreducing C$_{60}$ rotational disorder are discussed. Our results provide\nimportant considerations for past and future band structure studies as well as\nthe increasingly popular C$_{60}$ electronic device applications, especially\nthose making use of heterostructures.",
        "positive": "Voltage-amplified heat rectification in SIS junctions: The control of thermal fluxes -- magnitude and direction, in mesoscale and\nnanoscale electronic circuits can be achieved by means of heat rectification\nusing thermal diodes in two-terminal systems. The rectification coefficient\n$\\mathcal{R}$, given by the ratio of forward and backward heat fluxes, varies\nwith the design of the diode and the working conditions under which the system\noperates. A value of $\\mathcal{R}\\ll 1$ or $\\mathcal{R}\\gg 1$ is a signature of\nhigh heat rectification performance but current solutions allowing such ranges,\nnecessitate rather complex designs. Here, we propose a simple solution: the use\nof a superconductor-insulator-superconductor (SIS) junction under an applied\nfast oscillating (THz range) voltage as the control of the heat flow direction\nand magnitude can be done by tuning the initial value of the superconducting\nphase. Our theoretical model based on the Green functions formalism and\ncoherent transport theory, shows a possible sharp rise of the heat\nrectification coefficient with values up to $\\mathcal{R} \\approx 500$ beyond\nthe adiabatic regime. The influence of quantum coherent effects on heat\nrectification in the SIS junction is highlighted."
    },
    {
        "anchor": "Stochastic Dynamics of Resonance Electronic Energy Transfer in\n  Bi-Dimensional Overexcited Molecular Ensembles: We investigate theoretically the stochastic dynamics of Resonance Electronic\nEnergy Transfer (RET), in a bi-dimensional overexcited ensemble of donor and\nacceptor molecules. We find that, after initial optical excitation of all the\ndonors, the reaction kinetics is well-described by a non-linear mean-field\ntheory. The latter provides a solid way to define and compute an effective rate\nof RET, even for disordered samples. We predict that this effective rate scales\nas $\\left\\langle R \\right\\rangle^{\\alpha}$ with $\\left\\langle R \\right\\rangle$\nthe average distance between individual excited donors and their\nnearest-neighbor acceptor molecules, and $\\alpha \\in \\left\\lbrack -6,-2\n\\right\\rbrack$ an exponent depending on the spatial distribution of molecular\npairs in the sample. Using a kinetic Monte-Carlo approach, we show departures\nfrom this macroscopic mean-field description arising from fluctuations and\nspatial correlations between several molecules involved in the RET process. We\nexpect this prediction to be relevant for both molecular science and biology,\nwhere the control and optimization of the RET dynamics is a key issue.",
        "positive": "Carbon nanotube plectonemes: Loops of twisted helices: The relaxation of twist in elastic filaments often drives conformational\nchanges. We explore this paradigm using all-atom computations and report the\nformation of novel supercoiled shapes in individual carbon nanotubes (CNTs).\nDecreasing the end distance of torsionally constrained CNTs leads to\nspontaneous nucleation and growth of a nanotube plectoneme. We develop a\nstability diagram and comparisons with theoretical frameworks reveal the\nimportance of non-local van Der Waals interactions. In some cases, they\nstabilize the supercoiling to an extent that its tip locally kinks and then\nirreversibly reconstructs into a disordered yet strengthened structure that\ninvolves $sp^3$ bonding. The ability to engineer supercoiled conformations of\nCNTs and related nanoscale filaments opens the possibility of a unique set of\ntunable functional properties at the nanoscale."
    },
    {
        "anchor": "Local spin dynamic arising from the non-perturbative SU(2) gauge field\n  of the spin orbit effect: We use the non-perturbative gauge field approach to study the effects of spin\norbit coupling on the dynamic of magnetic moment. We present a general equation\nof motion (EOM) which unifies i) the spin orbit coupling effect derived from\nthe SU(2) spin gauge field, and ii) the moment chirality effect previously\nderived from the topological U(1)xU(1) rotation gauge under the adiabatic\ncondition. We present a modified Landau-Liftshitz-Gilbert equation and discuss\nthe implication of the modified EOM in various technological applications, such\nas current-induced switching and trajectory of magnetic moments in spin-valve\nmultilayers, magnetic memory and diluted magnetic semiconductor.",
        "positive": "Ab initio theory of graphene-iron(II) phthalocyanine hybrid systems as\n  scalable molecular spintronics: Graphene - transition metal phthalocyanine (G-MPc) hybrid systems constitute\npromising platforms for densely-packed single-molecule magnets (SMMs). Here, we\nselected iron(II) phthalocyanine (FePc) and investigated its interaction with\npristine and defective graphene layers employing density functional theory. Our\ncalculations indicate that thorough proper dehydrogenation of the benzol rings\nin the FePc molecule its adsorption to graphene is thermodynamically favorable.\nIn general, the presence of anchoring sites on the graphene layer, i.e. point\ndefects, additionally facilitates the adsorption of FePc, allowing one to\nachieve high density of SMMs per unit area. Using the combination of group\ntheory, ligand field splitting, and the calculated PBE0 Kohn-Sham eigenvalue\nspectrum, we resolved the electronic structure and predicted the spin states of\nboth, the isolated FePc and G-FePc hybrid systems. Regardless of adsorption\nsite and the number of removed hydrogen atoms from the benzol rings of FePc,\nthe magnetic moment of the SMM remains unchanged with respect to free FePc.\nThese results should mediate a successful synthesis of densely-packed G-MPc\nsystems and may open up new avenue in designing scalable graphene - SMMs\nsystems for spintronics applications."
    },
    {
        "anchor": "Reflection and refraction of an electron spin at the junction between\n  two two-dimensional regions with and without spin-orbit interaction: We derive the reflection and refraction laws for an electron spin incident\nfrom a quasi-two-dimensional medium with no spin-orbit interaction on another\nwith both Rashba and Dresselhaus spin-orbit interaction using only energy\nconservation. We obtain the well-known result that for an incident angle, there\ncan be generally two different refraction angles for refraction into the two\nspin eigenstates in the refraction medium, resulting in two different 'spin\nrefractive indices' and two critical angles for total internal reflection. We\nderive expressions for the spin refractive indices, which are not constant for\na given medium but depend on the incident electron's energy. If the effective\nmass of an electron in the refraction medium is larger than that in the\nincidence medium, then we show that for some incident electron energies and\npotential barrier at the interface, the spin refractive index of the incidence\nmedium can lie between the two spin refractive indices of the refraction\nmedium, resulting in only one critical angle. In that case, if the incident\nangle exceeds that critical angle, then refraction can occur into only one spin\neigenstate in the refraction medium. If the system is engineered to make this\nhappen, then it will be possible to obtain a very high degree of spin-polarized\ninjection into the refraction medium. The amplitudes of reflection of the\nincident spin into its own spin eigenstate and the orthogonal spin eigenstate\n(due to spin flip at the interface), as well as the refraction amplitudes into\nthe two spin eigenstates in the refraction medium are derived for an incident\nelectron (with arbitrary spin polarization and incident energy) as a function\nof the angle of incidence.",
        "positive": "Magnetic Focussing of Electrons and Holes in the presence of spin orbit\n  interactions: In this work we theoretically investigate transverse magnetic focussing in\ntwo dimensional electron and hole gasses with strong spin orbit interactions.\nWe present a general result for spin orbit interaction with singular winding\nnumbers in the adiabatic limit. We then present results for systems with two\nspin orbit interactions of different winding number appear, using the concrete\nand experimentally relevant case of an applied in-plane magnetic field in hole\nsystems with Rashba type interactions. We predict that the application of a\nlarge in-plane field is found to have a strong effect on the magnetic focussing\nspectrum."
    },
    {
        "anchor": "Fundamental exciton linewidth broadening in monolayer transition metal\n  dichalcogenides: Monolayer Transition Metal Dichalcogenides (TMDS) are highly luminescent\nmaterials despite being sub-nanometer thick due to the ultra-short ($<1$ ps)\nradiative lifetime of the strongly bound bright excitons hosted by these\nmaterials. The intrinsically short radiative lifetime results in a large\nbroadening in the exciton band with a magnitude that is about two orders\ngreater than the spread of the light cone itself. The situation calls for a\nneed to revisit the conventional light cone picture. We present a modified\nlight cone concept which places the light line $(\\hbar cQ)$ as the generalized\nlower bound for allowed radiative recombination. A self-consistent methodology,\nwhich becomes crucial upon inclusion of large radiative broadening in the\nexciton band, is proposed to segregate the radiative and the non-radiative\ncomponents of the homogeneous exciton linewidth. We estimate a fundamental\nradiative linewidth of $1.54\\pm0.17\\ $meV, owing purely to finite radiative\nlifetime in the absence of non-radiative dephasing processes. As a direct\nconsequence of the large radiative limit, we find a surprisingly large ($\\sim\n0.27 $ meV) linewidth broadening due to zero-point energy of acoustic phonons.\nThis obscures the precise experimental determination of the intrinsic radiative\nlinewidth and sets a fundamental limit on the non-radiative linewidth\nbroadening at $T = 0$ K.",
        "positive": "Wide Angle Dynamically Tunable Enhanced Infrared Absorption on Large\n  Area Nanopatterned Graphene: Enhancing light-matter interaction by exciting Dirac plasmons on\nnanopatterned monolayer graphene is an efficient route to achieve high infrared\nabsorption. Here, we designed and fabricated the hexagonal planar arrays of\nnanohole and nanodisk with and without optical cavity to excite Dirac plasmons\non the patterned graphene and investigated the role of plasmon lifetime,\nextinction cross-section, incident light polarization, the angle of incident of\nlight and pattern dimensions on the light absorption spectra."
    },
    {
        "anchor": "Magnetic brightening and control of dark excitons in monolayer WSe2: Monolayer transition metal dichalcogenide (TMDC) crystals, as direct-gap\nmaterials with unusually strong light-matter interaction, have attracted much\nrecent attention. In contrast to the initial understanding, the minima of the\nconduction band are predicted to be spin split. Because of this splitting and\nthe spin-polarized character of the valence bands, the lowest-lying excitonic\nstates in WX2 (X=S, Se) are expected to be spin-forbidden and optically dark.\nTo date, however, there has been no direct experimental probe of these dark\nband-edge excitons, which strongly influence the light emission properties of\nthe material. Here we show how an in-plane magnetic field can brighten the dark\nexcitonic states and allow their properties to be revealed experimentally in\nmonolayer WSe2. In particular, precise energy levels for both the neutral and\ncharged dark excitons were obtained and compared with ab-initio calculations\nusing the GW-BSE approach. Greatly increased emission and valley lifetimes were\nobserved for the brightened dark states as a result of their spin\nconfiguration. These studies directly probe the excitonic spin manifold and\nprovide a new route to tune the optical and valley properties of these\nprototypical two-dimensional semiconductors.",
        "positive": "Quantum gates by periodic driving: Topological quantum computation has been extensively studied due to its\nrobustness against decoherence. A conventional way to realize it is by\nadiabatic operations---it requires relatively long time to accomplish so that\nthe speed of quantum computation slows down. In this work, we present a method\nto realize topological quantum computation by periodic driving. Compared to the\nadiabatic evolution, the total operation time can be regulated arbitrarily by\nthe amplitude and frequency of the periodic driving. For the sinusoidal\ndriving, we give an expression for the total operation time in the\nhigh-frequency limit. For the square wave driving, we derive an exact\nanalytical expression for the evolution operator without any approximations,\nand show that the amplitude and frequency of driving field depend on its period\nand total operation time. This could provide a new direction in regulations of\nthe operation time in topological quantum computation."
    },
    {
        "anchor": "Creep of current-driven domain-wall lines: intrinsic versus extrinsic\n  pinning: We present a model for current-driven motion of a magnetic domain-wall line,\nin which the dynamics of the domain wall is equivalent to that of an overdamped\nvortex line in an anisotropic pinning potential. This potential has both\nextrinsic contributions due to, e.g., sample inhomogeneities, and an intrinsic\ncontribution due to magnetic anisotropy. We obtain results for the domain-wall\nvelocity as a function of current for various regimes of pinning. In\nparticular, we find that the exponent characterizing the creep regime depends\nstrongly on the presence of a dissipative spin transfer torque. We discuss our\nresults in the light of recent experiments on current-driven domain-wall creep\nin ferromagnetic semiconductors, and suggest further experiments to corroborate\nour model.",
        "positive": "Efficiency Limit Of AlxGa1-xAs Solar Cell Modified By AlyGa1-ySb Quantum\n  Dot Intermediate Band Embedded Outside Of The Depletion Region: Recombination through quantum dots (QDs) is a major factor that limits\nefficiency of QD intermediate-band (IB) solar cells. Our proposal for a new IB\nsolar cell based on type-II GaSb QDs located outside the depletion region of a\nGaAs p-n-junction aims to solve this problem. The important advantage of\nproposed heterostructure appears due to the outside location of IB. Such IB\ndoes not assist generation of additional leakage current flow through the\ndepletion region. Carriers cannot escape from outside QDs through the buffer\nlayer and the depletion region into GaAs substrate by tunneling because QDs are\nfar from the depletion layer. Only solar photon or thermal assistance may\nenable electron escape from QDs. Such type-II QD IB solar cell concept promises\nan efficiency enhancement relative to that of GaAs solar cells."
    },
    {
        "anchor": "From Graphene constrictions to single carbon chains: We present an atomic-resolution observation and analysis of graphene\nconstrictions and ribbons with sub-nanometer width. Graphene membranes are\nstudied by imaging side spherical aberration-corrected transmission electron\nmicroscopy at 80 kV. Holes are formed in the honeycomb-like structure due to\nradiation damage. As the holes grow and two holes approach each other, the\nhexagonal structure that lies between them narrows down. Transitions and\ndeviations from the hexagonal structure in this graphene ribbon occur as its\nwidth shrinks below one nanometer. Some reconstructions, involving more\npentagons and heptagons than hexagons, turn out to be surprisingly stable.\nFinally, single carbon atom chain bridges between graphene contacts are\nobserved. The dynamics are observed in real time at atomic resolution with\nenough sensitivity to detect every carbon atom that remains stable for a\nsufficient amount of time. The carbon chains appear reproducibly and in various\nconfigurations from graphene bridges, between adsorbates, or at open edges and\nseem to represent one of the most stable configurations that a few-atomic\ncarbon system accomodates in the presence of continuous energy input from the\nelectron beam.",
        "positive": "Transmission and Goos-H\u00e4nchen like Shifts through a Graphene Double\n  Barrier in an Inhomogeneous Magnetic Field: We studied the transport properties of electrons in graphene as they are\nscattered by a double barrier potential in the presence of an inhomogeneous\nmagnetic field. We computed the transmission coefficient and Goos-H\\\"anchen\nlike shifts for our system and noticed that transmission is not allowed for\ncertain range of energies. In particular, we found that, in contrast to the\nelectrostatic barriers, the magnetic barriers are able to confine Dirac\nfermions. We also established some correlation between the electronic\ntransmission properties of Dirac fermions with the Goos-H\\\"anchen like shifts,\nas reflected in the numerical data."
    },
    {
        "anchor": "Cross-Polarized Microwave Surface-State Anti-Resonance: We propose a polarization-sensitive measurement of microwave electromagnetic\nresonances in a magnetic field to detect the metallic surface state of a bulk\ninsulator. A quantitative model is used to demonstrate that a unique,\nunambiguous signature of the dissipative but conducting surface can be seen in\nthe orthogonally polarized transmission spectra.",
        "positive": "Josephson current in carbon nanotubes with spin-orbit interaction: We demonstrate that curvature-induced spin-orbit (SO) coupling induces a\n$0-\\pi$ transition in the Josephson current through a carbon nanotube quantum\ndot coupled to superconducting leads. In the non-interacting regime, the\ntransition can be tuned by applying parallel magnetic field near the critical\nfield where orbital states become degenerate. Moreover, the interplay between\ncharging and SO effects in the Coulomb Blockade and cotunneling regimes leads\nto a rich phase diagram with well-defined (analytical) boundaries in parameter\nspace. Finally, the 0 phase always prevails in the Kondo regime. Our\ncalculations are relevant in view of recent experimental advances in transport\nthrough ultra-clean carbon nanotubes."
    },
    {
        "anchor": "Molecular Dynamics Study of sp-Defect Migration in Odd Fullerene:\n  Possible Role in Synthesis of Abundant Isomers of Fullerenes: To explain recent experiment showing the role of odd fullerenes in formation\nof abundant fullerene isomers a reactive molecular dynamics (MD) study has been\nperformed. Three types of bond rearrangement reactions are found by MD\nsimulations at 3000 K in odd fullerenes which contain an extra sp atom among\nall other sp$^2$ atoms. The first type is sto-chastic sp-defect migration\nanalogous to exchange mechanism of adatom migration on a surface. The second\ntype cor-responds to changes in the ring configuration of the sp$^2$-structure\nassisted by the sp atom which can lead to annealing of seven-membered rings or\nseparation of five-membered rings. The third type is formation of short-living\none-coordinated atoms or two additional sp atoms. Annihilation of a pair of sp\ndefects has been also observed in the MD simulations. It is shown that the\nfrequency of sp-defect migration at a lower temperature, as estimated from\nperformed density functional theory calculations of the barriers of sp-defect\nmigration events, is sufficient to deliver the sp atom to defects of sp$^2$\nstructure during the fullerene formation time. Based on these results, we\npropose to supplement the self-organization paradigm of fullerene formation by\nthe following four-stage atomistic mechanism of formation of abundant isomers\nof fullerenes: 1) attachment of single carbon atoms, 2) sp-defect migration to\nsp$^2$-structure defects, 3) sp$^2$-defect annealing assisted by the sp atom\nand 4) subsequent annihilation of pairs of sp defects.",
        "positive": "Gate-controlled supercurrent reversal in MoS$_2$-based Josephson\n  junctions: Motivated by recent experiments revealing superconductivity in MoS$_2$, we\ninvestigate the Josephson effect in the monolayer MoS$_2$ at the presence of an\nexchange splitting. We show that the supercurrent reversal known as $0-\\pi$\ntransition can occur by varying the doping via gate voltages. This is in\ncontrast to common superconductor/ferromagnet/superconductor junctions in which\nsuccessive $0-\\pi$ transition take place with the variation of junction length\nor temperature. In fact for the case of MoS$_2$ we find that both the amplitude\nand the period of oscillations show a dependence on the doping which explains\nthe predicted doping induced supercurrent reversal. These effects comes from\nthe dependence of density and Fermi velocity on the doping strength beside the\nintrinsic spin splitting in the valence band which originates from spin-orbit\ninteraction."
    },
    {
        "anchor": "Current induced spin flip scattering at interfaces in noncollinear\n  magnetic multilayers: We show that when one drives a charge current across noncollinear magnetic\nlayers the two electron Coulomb scattering creates a spin flip potential at\ninterfaces. This scattering is found when the interface potential is updated\ndue to the spin accumulation attendant to charge flow, and it contributes in\nlinear response to the current. With this scattering there is an injection of\ntransverse spin distributions in a layer that propagate, and that in the steady\nstate lead to spin currents transverse to the magnetization.",
        "positive": "Optical and transport properties of low-dimensional semiconductor\n  nanostructures: The interpretation of the electronic kinetic processes in the quantum zero\ndimensional nanostructures is considered. The main mechanism of the processes\nis supposed to be the interaction of electrons with the optical phonons. An\nemphasis is put on the recently measured effect of the long-time\nphotoluminescence of quantum dot samples, which is observed to occur after an\nillumination of the sample by a laser pulse. In addition to this, an attention\nis devoted to the possible origin of the optical effect of the blinking\n(intermittence) of the optical emission of certain quantum dot samples under a\npermanent optical excitation, and to another similar effect."
    },
    {
        "anchor": "Direct observation of anyonic braiding statistics at the $\u03bd$=1/3\n  fractional quantum Hall state: Utilizing an electronic Fabry-Perot interferometer in which Coulomb charging\neffects are suppressed, we report experimental observation of anyonic braiding\nstatistics for the $\\nu=1/3$ fractional quantum Hall state. Strong\nAharonov-Bohm interference of the $\\nu=1/3$ edge mode is punctuated by discrete\nphase slips consistent with an anyonic phase of\n$\\theta_{anyon}=\\frac{2\\pi}{3}$. Our results are consistent with a recent\ntheory of a Fabry-Perot interferometer operated in a regime in which device\ncharging energy is small compared to the energy of formation of charged\nquasiparticles. Close correspondence between device operation and theoretical\npredictions substantiates our claim of observation of anyonic braiding.",
        "positive": "Immense magnetic response of exciplex light emission due to correlated\n  spin-charge dynamics: As carriers slowly move through a disordered energy landscape in organic\nsemiconductors, tiny spatial variations in spin dynamics relieve spin blocking\nat transport bottlenecks or in the electron-hole recombination process that\nproduces light. Large room-temperature magnetic-field effects (MFE) ensue in\nthe conductivity and luminescence. Sources of variable spin dynamics generate\nmuch larger MFE if their spatial structure is correlated on the nanoscale with\nthe energetic sites governing conductivity or luminescence such as in\nco-evaporated organic blends within which the electron resides on one molecule\nand the hole on the other (an exciplex). Here we show that exciplex\nrecombination in blends exhibiting thermally-activated delayed fluorescence\n(TADF) produces MFE in excess of 60% at room temperature. In addition, effects\ngreater than 4000% can be achieved by tuning the device's current-voltage\nresponse curve by device conditioning. These immense MFEs are both the largest\nreported values for their device type at room temperature. Our theory traces\nthis MFE and its unusual temperature dependence to changes in spin mixing\nbetween triplet exciplexes and light-emitting singlet exciplexes. In contrast,\nspin mixing of excitons is energetically suppressed, and thus spin mixing\nproduces comparatively weaker MFE in materials emitting light from excitons by\naffecting the precursor pairs. Demonstration of immense MFE in common organic\nblends provides a flexible and inexpensive pathway towards magnetic\nfunctionality and field sensitivity in current organic devices without\npatterning the constituent materials on the nanoscale. Magnetic fields increase\nthe power efficiency of unconditioned devices by 30% at room temperature, also\nshowing that magnetic fields may increase the efficiency of the TADF process."
    },
    {
        "anchor": "Mesoscopic Transport of Entangled and Nonentangled Kondo Singlets under\n  Bias: The tunneling conductances of a quantum point contact and a magnetized atom\nadsorbed on an insulating layer above a metallic substrate are obtained by\nconsidering the coherent transport of the entangled and nonentangled Kondo\nsinglets, and these are compared with the experimental results. Spins of the\nentangled Kondo singlet flow unidirectionally in a sequential up-and-down\nmanner. This transport does not follow linear response theory. The nonentangled\nKondo singlet performs resonant tunneling through a coherent transport channel\nand yields coherent side peaks at a finite bias. The coherent transport channel\nis formed by two electron reservoirs within a coherent region.",
        "positive": "Polaronic effects in electron shuttling: Shuttle-like mechanism of electron transport through a single level vibrating\nquantum dot is considered in the regime of strong electromechanical coupling.\nIt is shown that the increment of shuttle instability is a nonmonotonic\nfunction of the driving voltage. The interplay of two oppositely acting effects\n- vibron-assisted electron tunneling and polaronic blockade - results in\noscillations of the increment on the energy scale of vibron energy."
    },
    {
        "anchor": "Efficient Solutions of Fermionic Systems using Artificial Neural\n  Networks: We discuss differences and similarities between variational Monte Carlo\napproaches that use conventional and artificial neural network\nparameterizations of the ground-state wave function for systems of fermions. We\nfocus on a relatively shallow neural-network architectures, the so called\nrestricted Boltzmann machine, and discuss unsupervised learning algorithms that\nare suitable to model complicated many-body correlations. We analyze the\nstrengths and weaknesses of conventional and neural-network wave functions by\nsolving various circular quantum-dots systems. Results for up to 90 electrons\nare presented and particular emphasis is placed on how to efficiently implement\nthese methods on homogeneous and heterogeneous high-performance computing\nfacilities.",
        "positive": "Enhanced dual-beam excitation photoelectric detection of NV magnetic\n  resonances in diamond: The core issue for the implementation of the diamond NV centre qubits\ntechnology is the sensitive readout of NV spin state. We have recently\ndemonstrated the photoelectric detection of NV magnetic resonances (PDMR),\nanticipated to be faster and more sensitive than optical detection (ODMR). Here\nwe report on a PDMR contrast of 9 % - three times enhanced compared to previous\nwork - on shallow N-implanted diamond. Based on ab-initio modelling, we\ndemonstrate a novel one-photon ionization dual-beam PDMR protocol. We predict\nthat this scheme is significantly less vulnerable to the influence of defects\nsuch as substitutional nitrogen."
    },
    {
        "anchor": "Gate-Tunable Graphene Hall Sensors with High Magnetic Field Sensitivity: Solid-state magnetic field sensors are important to both modern electronics\nand fundamental materials science. Many types of these sensors maintain high\nsensitivity only in a limited range of temperature and background magnetic\nfield, but Hall-effect sensors are in principle able to operate over a broad\nrange of these conditions. Here, we fabricate and characterize micrometer-scale\ngraphene Hall sensors demonstrating high magnetic field sensitivity from\nliquid-helium to room temperature and in background magnetic field up to\nseveral Tesla. By tuning the charge carrier density with an electrostatic gate,\nwe optimize the magnetic field sensitivity for different working conditions.\nFrom measurements of the Hall coefficient and the Hall voltage noise at 1 kHz,\nwe estimate an optimum magnetic field sensitivity of 80 nT Hz$^{-1/2}$ at 4.2\nK, 700 nT Hz$^{-1/2}$ at room temperature, and 3 $\\mu$T Hz$^{-1/2}$ in 3 T\nbackground magnetic field at 4.2 K. Our devices perform competitively with the\nbest existing Hall sensor technologies at room temperature, outperform any Hall\nsensors reported in the literature at 4.2 K, and demonstrate high sensitivity\nfor the first time in a few Tesla applied magnetic field.",
        "positive": "Unified framework of the microscopic Landau-Lifshitz-Gilbert equation\n  and its application to Skyrmion dynamics: The Landau-Lifshitz-Gilbert (LLG) equation is widely used to describe\nmagnetization dynamics. We develop a unified framework of the microscopic LLG\nequation based on the nonequilibrium Green's function formalism. We present a\nunified treatment for expressing the microscopic LLG equation in several\nlimiting cases, including the adiabatic, inertial, and nonadiabatic limits with\nrespect to the precession frequency for a magnetization with fixed magnitude,\nas well as the spatial adiabatic limit for the magnetization with slow\nvariation in both its magnitude and direction. The coefficients of those terms\nin the microscopic LLG equation are explicitly expressed in terms of\nnonequilibrium Green's functions. As a concrete example, this microscopic\ntheory is applied to simulate the dynamics of a magnetic Skyrmion driven by\nquantum parametric pumping. Our work provides a practical formalism of the\nmicroscopic LLG equation for exploring magnetization dynamics."
    },
    {
        "anchor": "Nanotube Quantum Dot Transport With Spin-Orbit Coupling and Interacting\n  Leads: We analyzed the effects of a spin voltage as well as a conventionally applied\nvoltage in a QD system with a different number of quantum states in the dot\nregion in presence of Coulombic interaction between the quantum dot and two\nleads. We extended the NEGF treatment developed for noninteracting leads onto\nthe case of four quantum states $m =\\{\\sigma,\\lambda\\}=\\{\\pm,\\pm\\}$ interacting\nwith leads. Our derivation is based on the equation-of-motion technique and\nLangreth's theorem. For a Coulombic repulsion between the contacts and QD we\nobtain an expression for the current through QD for the four quantum states. To\ndetermine the parameters of the model Hamiltonian we used our previous\ncalculations [1] of the electronic properties of a symmetrical nanotube QD\n(5,5)/(10,0)\\_1/(5,5) in a tight binding model, where \\_1 denotes the length of\nthe middle QD segment of a (10,0) zigzag nanotube. We calculated the density of\nelectronic states with spin up and down for the case of a single QD without\npseudospin states for an infinite Coulomb repulsion, in good agreement with the\ncalculations of Yuan Li, et al. [2]. Our calculation showed that the position\nof the conductance peaks nearest to zero is not affected by the strength of the\nQD-lead Coulombic interaction parameters. We also demonstrated that this\ninteraction shifts the density of states to higher energies. The interplay\nbetween the Kondo effect and the bias is highly temperature-dependent and\nbecomes significant only at low temperatures. Lastly, we found that the\nexistence of four quantum states $m=\\{\\sigma,\\lambda\\}$ leads to abrupt changes\nin the density of states. In this case the values of the current are\napproximately ten times lower than for QD with only two quantum states $m\n=\\{\\sigma\\}=\\{\\pm\\}$. However, in the case of a conventional bias the current\namplitudes in both cases are approximately the same.",
        "positive": "Tunable chiral symmetry breaking in symmetric Weyl materials: Asymmetric Weyl semimetals, which possess an inherently chiral structure,\nhave different energies and dispersion relations for left- and right-handed\nfermions. They exhibit certain effects not found in symmetric Weyl semimetals,\nsuch as the quantized circular photogalvanic effect and the helical magnetic\neffect. In this work, we derive the conditions required for breaking chiral\nsymmetry by applying an external field in symmetric Weyl semimetals. We\nexplicitly demonstrate that in certain materials with the $T_d$ point group,\nmagnetic fields along low symmetry directions break the symmetry between left-\nand right-handed fermions; the symmetry breaking can be tuned by changing the\ndirection and magnitude of the magnetic field. In some cases, we find an\nimbalance between the number of type I left- and right-handed Weyl cones (which\nis compensated by the number of type II cones of each chirality.)"
    },
    {
        "anchor": "The optomechanical instability in the quantum regime: We consider a generic optomechanical system, consisting of a driven optical\ncavity and a movable mirror attached to a cantilever. Systems of this kind (and\nanalogues) have been realized in many recent experiments. It is well known that\nthose systems can exhibit an instability towards a regime where the cantilever\nsettles into self-sustained oscillations. In this paper, we briefly review the\nclassical theory of the optomechanical instability, and then discuss the\nfeatures arising in the quantum regime. We solve numerically a full quantum\nmaster equation for the coupled system, and use it to analyze the photon\nnumber, the cantilever's mechanical energy, the phonon probability distribution\nand the mechanical Wigner density, as a function of experimentally accessible\ncontrol parameters. We observe and discuss the quantum-to-classical transition\nas a function of a suitable dimensionless quantum parameter.",
        "positive": "Structures for Data Processing in the Quantum Regime: We present a novel scheme for data processing which is well-suited for\nimplementation at the nanometer scale. The logic circuits comprise two-state\ncellular units which are driven by externally applied updates, in contrast to\nearlier proposals which relied on ground-state relaxation. The present\nstructures can simultaneously process many inputs and are suitable for\nconventional, dissipative computing in addition to classical reversible\ncomputing and quantum computing."
    },
    {
        "anchor": "The diamond Nitrogen-Vacancy center as a probe of random fluctuations in\n  a nuclear spin ensemble: New schemes that exploit the unique properties of Nitrogen-Vacancy (NV)\ncenters in diamond are presently being explored as a platform for\nhigh-resolution magnetic sensing. Here we focus on the ability of a NV center\nto monitor an adjacent mesoscopic nuclear spin bath. For this purpose, we\nconduct comparative experiments where the NV spin evolves under the influence\nof surrounding 13C nuclei or, alternatively, in the presence of asynchronous AC\nfields engineered to emulate bath fluctuations. Our study reveals substantial\ndifferences that underscore the limitations of the semi-classical picture when\ninterpreting and predicting the outcome of experiments designed to probe small\nnuclear spin ensembles. In particular, our study elucidates the NV center\nresponse to bath fluctuations under common pulse sequences, and explores a\ndetection protocol designed to probe time correlations of the nuclear spin bath\ndynamics. Further, we show that the presence of macroscopic nuclear spin order\nis key to the emergence of semi-classical spin magnetometry.",
        "positive": "Optoelectronic Sensitization of Carbon Nanotubes by CdTe Nanocrystals: We investigate the photoconductance of single-walled carbon\nnanotube-nanocrystalhybrids. The nanocrystals are bound to the nanotubes via\nmolecular recognition. We find that the photoconductance of the hybrids can be\nadjusted by the absorption characteristics of the nanocrystals. In addition,\nthe photoconductance of the hybrids surprisingly exhibits a slow time constant\nof about 1 ms after excitation of the nanocrystals. The data are consistent\nwith a bolometrically induced current increase in the nanotubes caused by\nphoton absorption in the nanocrystals."
    },
    {
        "anchor": "Many-body spectral functions from steady state density functional theory: We propose a scheme to extract the many-body spectral function of an\ninteracting many-electron system from an equilibrium density functional theory\n(DFT) calculation. To this end we devise an ideal STM-like setup and employ the\nrecently proposed steady-state DFT formalism (i-DFT) which allows to calculate\nthe steady current through a nanoscopic region coupled to two biased\nelectrodes. In our setup one of the electrodes serves as a probe ('STM tip'),\nwhich is weakly coupled to the system we want to measure. In the ideal STM\nlimit of vanishing coupling to the tip, the system is restored to\nquasi-equilibrium and the normalized differential conductance yields the exact\nequilibrium many-body spectral function. Calculating this quantity from i-DFT,\nwe derive an exact relation expressing the interacting spectral function in\nterms of the Kohn-Sham one. As illustrative examples we apply our scheme to\ncalculate the spectral functions of two non-trivial model systems, namely the\nsingle Anderson impurity model and the Constant Interaction Model.",
        "positive": "Low frequency noise due to magnetic inhomogeneities in submicron\n  FeCoB/MgO/FeCoB magnetic tunnel junctions: We report on room temperature low frequency noise due to magnetic\ninhomogeneities/domain walls (MI/DWs) in elliptic submicron FeCoB/MgO/FeCoB\nmagnetic tunnel junctions with an area between 0.0245 and 0.0675{\\mu}m2. In the\nsmaller area junctions we found an unexpected random telegraph noise (RTN1),\ndeeply in the parallel state, possibly due to stray field induced MI/DWs in the\nhard layer. The second noise source (RTN2) is observed in the antiparallel\nstate for the largest junctions. Strong asymmetry of RTN2 and of related\nresistance steps with current indicate spin torque acting on the MI/DWs in the\nsoft layer at current densities below 5x10^5 A/cm2."
    },
    {
        "anchor": "Quantum dots in suspended single-wall carbon nanotubes: We present a simple technique which uses a self-aligned oxide etch to suspend\nindividual single-wall carbon nanotubes between metallic electrodes. This\nenables one to compare the properties of a particular nanotube before and after\nsuspension, as well as to study transport in suspended tubes. As an example of\nthe utility of the technique, we study quantum dots in suspended tubes, finding\nthat their capacitances are reduced owing to the removal of the dielectric\nsubstrate.",
        "positive": "Multiwavelength electron diffraction as a tool for identifying stacking\n  sequences in 2D materials: Two-dimensional (2D) materials are among the most studied ones nowadays,\nbecause of their unique properties. These materials are made of, single- or few\natom-thick layers assembled by van der Waals forces, hence allowing a variety\nof stacking sequences possibly resulting in a variety of crystallographic\nstructures as soon as the sequences are periodic. Taking the example of few\nlayer graphene (FLG), it is of an utmost importance to identify both the number\nof layers and the stacking sequence, because of the driving role these\nparameters have on the properties. For this purpose, analysing the spot\nintensities of electron diffraction patterns (DPs) is commonly used, along with\nattempts to vary the number of layers, and the specimen tilt angle. However,\nthe number of sequences able to be discriminated this way remains few, because\nof the similarities between the DPs. Also, the possibility of the occurrence of\nC layers in addition to A and/or B layers in FLG has been rarely considered. To\novercome this limitation, we propose here a new methodology based on\nmulti-wavelength electron diffraction which is able to discriminate between\nstacking sequences up to 6 layers (potentially more) involving A, B, and C\nlayers. We also propose an innovative method to calculate the spot intensities\nin an easier and faster way than the standard ones. Additionally, we show that\nthe method is valid for transition metal dichalcogenides, taking the example of\nMoS2."
    },
    {
        "anchor": "Possible Giant Orbital Paramagnetism in Nanometer Scale 2DEG Strips: An elementary calculation shows that Landau diamagnetism becomes\nsignificantly altered and very large paramagnetic effects emerge at low\ntemperature in nanoscale 2DEG strips penetrated by a perpendicular applied\nmagnetic field and bounded by a parabolic potential, such as may arise from\nnegative voltage applied to a split gate. These novel results are described by\nan expression which manifests the total system magnetization as a difference\nbetween evolved orbital paramagnetism and altered diamagnetism. These predicted\neffects correspond to drift motion of electrons parallel to the strip length\narising from Landau eigenstates that are non-degenerate in the combined\npresence of a perpendicular applied magnetic field and electric fields\nassociated with a confining parabolic potential. A new heterostructured\nmagnetic material based on orbital electronic motion in 2DEG strips is\nproposed.",
        "positive": "Numerical Studies on Antiferromagnetic Skyrmions in Nanodisks by Means\n  of A New Quantum Simulation Approach: We employ a self-consistent simulation approach based on quantum physics here\nto study the magnetism of antiferromagnetic skyrmions formed on manolayer\nnanodisk planes. We find that if the disk is small and the Dzyaloshinsky-Moriya\n(DM) interaction is weak, a single magnetic vortex may be formed on the disk\nplane. In such a case, when uniaxial anisotropy normal to the disk plane is\nfurther considered, the magnetic configuration remains unchanged, but the\nmagnetization is enhanced in that direction, and reduced in other two\nperpendicular orientations. Very similarly, a weak external magnetic field\nnormal to the disk plane cannot obviously affect the spin structure of the\nnanodisk; however, when it is sufficiently strong, it can destroy the AFM\nskyrmion completely. On the other hand, by increasing DM interaction so that\nthe disk diameter is a few times larger than the DM length, more self-organized\nmagnetic domains, such as vortices and strips, will be formed in the disk\nplane. They evolve with decreasing temperature, however always symmetric about\na geometric axis of the square unit cell. We further find that in this case\nintroducing normal magnetic anisotropy gives rise to the re-construction of AFM\nsingle-vortex structure or skyrmion on the disk plane, which provides a way to\ncreate and/or stabilize such spin texture in experiment."
    },
    {
        "anchor": "Conductance spectra of metallic nanotube bundles: We report a first principles analysis of electronic transport characteristics\nfor (n,n) carbon nanotube bundles. When n is not a multiple of 3, inter-tube\ncoupling causes universal conductance suppression near Fermi level regardless\nof the rotational arrangement of individual tubes. However, when n is a\nmultiple of 3, the bundles exhibit a diversified conductance dependence on the\norientation details of the constituent tubes. The total energy of the bundle is\nalso sensitive to the orientation arrangement only when n is a multiple of 3.\nAll the transport properties and band structures can be well understood from\nthe symmetry consideration of whether the rotational symmetry of the individual\ntubes is commensurate with that of the bundle.",
        "positive": "Finite-size effects in wave transmission through plasmonic crystals: A\n  tale of two scales: We study optical coefficients that characterize wave propagation through\nlayered structures called plasmonic crystals. These consist of a finite number\nof stacked metallic sheets embedded in dielectric hosts with a subwavelength\nspacing. By adjustment of the frequency, spacing, number as well as geometry of\nthe layers, these structures may exhibit appealing transmission properties in a\nrange of frequencies from the terahertz to the mid-infrared regime. Our\napproach uses a blend of analytical and numerical methods for the distinct\ngeometries with infinite, translation invariant, flat sheets and nanoribbons.\nWe describe the transmission of plane waves through a plasmonic crystal in\ncomparison to an effective dielectric slab of equal total thickness that\nemerges from homogenization, in the limit of zero interlayer spacing. We\ndemonstrate numerically that the replacement of the discrete plasmonic crystal\nby its homogenized counterpart can accurately capture a transmission\ncoefficient akin to the extinction spectrum, even for a relatively small number\nof layers. We point out the role of a geometry-dependent corrector field, which\nexpresses the effect of subwavelength surface plasmons. In particular, by use\nof the corrector we describe lateral resonances inherent to the nanoribbon\ngeometry."
    },
    {
        "anchor": "Broadband frequency filters with quantum dot chains: Two-terminal electronic transport systems with a rectangular transmission can\nviolate standard thermodynamic uncertainty relations. This is possible beyond\nthe linear response regime and for parameters that are not accessible with rate\nequations obeying detailed-balance. Looser bounds originating from fluctuation\ntheorem symmetries alone remain respected. We demonstrate that optimal\nfinite-sized quantum dot chains can implement rectangular transmission\nfunctions with high accuracy and discuss the resulting violations of standard\nthermodynamic uncertainty relations as well as heat engine performance.",
        "positive": "Ultrafast band-gap renormalization and build-up of optical gain in\n  monolayer MoTe$_2$: The dynamics of band-gap renormalization and gain build-up in monolayer\nMoTe$_2$ is investigated by evaluating the non-equilibrium Dirac-Bloch\nequations with the incoherent carrier-carrier and carrier-phonon scattering\ntreated via quantum-Boltzmann type scattering equations. For the case where an\napproximately $300$ fs-long high intensity optical pulse generates\ncharge-carrier densities in the gain regime, the strong Coulomb coupling leads\nto a relaxation of excited carriers on a few fs time scale. The pump-pulse\ngeneration of excited carriers induces a large band-gap renormalization during\nthe time scale of the pulse. Efficient phonon coupling leads to a subsequent\ncarrier thermalization within a few ps, which defines the time scale for the\noptical gain build-up energetically close to the low-density exciton resonance."
    },
    {
        "anchor": "Generating Entanglement and Squeezed States of Nuclear Spins in Quantum\n  Dots: Entanglement generation and detection are two of the most sought-after goals\nin the field of quantum control. Besides offering a means to probe some of the\nmost peculiar and fundamental aspects of quantum mechanics, entanglement in\nmany-body systems can be used as a tool to reduce fluctuations below the\nstandard quantum limit. For spins, or spin-like systems, such a reduction of\nfluctuations can be realized with so-called squeezed states. Here we present a\nscheme for achieving coherent spin squeezing of nuclear spin states in\nfew-electron quantum dots. This work represents a major shift from earlier\nstudies in quantum dots, which have explored classical \"narrowing\" of the\nnuclear polarization distribution through feedback involving stochastic spin\nflips. In contrast, we use the nuclear-polarization-dependence of the electron\nspin resonance (ESR) to provide a non-linearity which generates a non-trivial,\narea-preserving, \"twisting\" dynamics that squeezes and stretches the nuclear\nspin Wigner distribution without the need for nuclear spin flips.",
        "positive": "Spin-orbit pumping: We study theoretically the effect of a rotating electric field on a diffusive\nnanowire and find an effect that is analogous to spin pumping, which refers to\nthe generation of spin through a rotating magnetic field. The electron spin\ncouples to the electric field because the particle motion induces an effective\nmagnetic field in its rest frame. In a diffusive system the velocity of the\nparticle, and therefore also its effective magnetic field, rapidly and randomly\nchanges direction. Nevertheless, we demonstrate analytically and via a physical\nargument why the combination of the two effects described above produces a\nfinite magnetization along the axis of rotation. This manifests as a measurable\nspin-voltage in the range of tens of microvolts."
    },
    {
        "anchor": "Key points in the determination of the interfacial Dzyaloshinskii-Moriya\n  interaction from asymmetric bubble domain expansion: Different models have been used to evaluate the interfacial\nDzyaloshinskii-Moriya interaction (DMI) from the asymmetric bubble expansion\nmethod using magneto-optics. Here we investigate the most promising candidates\nover a range of different magnetic multilayers with perpendicular anisotropy.\nModels based on the standard creep hypothesis are not able to reproduce the\ndomain wall (DW) velocity profile when the DW roughness is high. Our results\ndemonstrate that the DW roughness and the interface roughness of the sample\nlayers are correlated. Furthermore, we give guidance on how to obtain reliable\nresults for the DMI value with this popular method. A comparison of the results\nwith Brillouin light scattering (BLS) measurements on the same samples shows\nthat the BLS approach often results in higher measured values of DMI.",
        "positive": "In-flight distribution of an electron within a surface acoustic wave: Surface acoustic waves (SAW) have large potential to realize\nquantum-optics-like experiments with single flying electrons employing their\nspin or charge degree of freedom. For such quantum applications, highly\nefficient trapping of the electron in a specific moving quantum dot (QD) of a\nSAW train plays a key role. Probabilistic transport over multiple moving minima\nwould cause uncertainty in synchronisation that is detrimental for coherence of\nentangled flying electrons and in-flight quantum operations. It is thus of\ncentral importance to identify the device parameters enabling electron\ntransport within a single SAW minimum. A detailed experimental investigation of\nthis aspect is so far missing. Here we fill this gap by demonstrating\ntime-of-flight measurements for a single electron that is transported via a SAW\ntrain between distant stationary QDs. Our measurements reveal the in-flight\ndistribution of the electron within the moving acousto-electric quantum dots of\nthe SAW train. Increasing the acousto-electric amplitude, we observe the\nthreshold necessary to confine the flying electron at a specific, deliberately\nchosen SAW minimum. Investigating the effect of a barrier along the transport\nchannel, we also benchmark the robustness of SAW-driven electron transport\nagainst stationary potential variations. Our results pave the way for highly\ncontrolled transport of electron qubits in a SAW-driven platform for quantum\nexperiments."
    },
    {
        "anchor": "Electronic transport in films of colloidal CdSe nanocrystals: We present results for electronic transport measurements on large\nthree-dimensional arrays of CdSe nanocrystals. In response to a step in the\napplied voltage, we observe a power-law decay of the current over five orders\nof magnitude in time. Furthermore, we observe no steady-state dark current for\nfields up to 10^6 V/cm and times as long as 2x10^4 seconds. Although the\npower-law form of the decay is quite general, there are quantitative variations\nwith temperature, applied field, sample history, and the material parameters of\nthe array. Despite evidence that the charge injected into the film during the\nmeasurement causes the decay of current, we find field-scaling of the current\nat all times. The observation of extremely long-lived current transients\nsuggests the importance of long-range Coulomb interactions between charges on\ndifferent nanocrystals.",
        "positive": "Square skyrmion crystal in centrosymmetric systems with locally\n  inversion-asymmetric layers: We investigate an instability toward a square-lattice formation of magnetic\nskyrmions in centrosymmetric layered systems. By focusing on a bilayer\nsquare-lattice structure with the inversion center at the interlayer bond\ninstead of the atomic site, we numerically examine the stability of the square\nskyrmion crystal based on an effective spin model with the momentum-resolved\ninteraction in the ground state through the simulated annealing. As a result,\nwe find that a layer-dependent staggered Dzyaloshinskii-Moriya interaction\nbuilt in the lattice structure becomes the origin of the square skyrmion\ncrystal in an external magnetic field irrespective of the sign of the\ninterlayer exchange interaction. The obtained square skyrmion crystal is\nconstituted of the skyrmion crystals with different helicities in each layer\ndue to the staggered Dzyaloshinskii-Moriya interaction. Furthermore, we show\nthat the interplay between the staggered Dzyaloshinskii-Moriya interaction and\nthe interlayer exchange interaction gives rise to a double-$Q$ state with a\nuniform component of the scalar chirality in the low-field region. The present\nresults provide another way of stabilizing the square skyrmion crystal in\ncentrosymmetric magnets, which will be useful to explore further exotic\ntopological spin textures."
    },
    {
        "anchor": "Anisotropic magneto-photothermal voltage in Sb2Te3 topological insulator\n  thin films: We studied longitudinal and Hall photothermal voltages under a planar\nmagnetic field scan in epitaxial thin films of the Topological Insulator (TI)\nSb2Te3, grown using pulsed laser deposition (PLD). Unlike prior research that\nutilised polarised light-induced photocurrent to investigate the TI, our study\nintroduces advancements based on unpolarized light-induced local heating. This\nmethod yields a thermoelectric response exhibiting a direct signature of strong\nspin-orbit coupling. Our analysis reveals three distinct contributions when\nfitting the photothermal voltage data to the angular dependence of the planar\nmagnetic field. The interaction between the applied magnetic field and the\nthermal gradient on the bulk band orbitals enables the differentiation between\nthe ordinary Nernst effect from the out-of-plane thermal gradient and an\nextraordinary magneto-thermal contribution from the planar thermal gradient.\nThe fitting of our data to theoretical models indicates that these effects\nprimarily arise from the bulk states of the TI rather than the surface states.\nThese findings highlight PLD-grown epitaxial topological insulator thin films\nas promising candidates for optoelectronic devices, including sensors and\nactuators. Such devices offer controllable responses through\nposition-dependent, non-invasive local heating via focused incident light and\nvariations in the applied magnetic field direction.",
        "positive": "Unconventional quantum Hall effect and Berry's phase of 2pi in bilayer\n  graphene: There are known two distinct types of the integer quantum Hall effect. One is\nthe conventional quantum Hall effect, characteristic of two-dimensional\nsemiconductor systems, and the other is its relativistic counterpart recently\nobserved in graphene, where charge carriers mimic Dirac fermions characterized\nby Berry's phase pi, which results in a shifted positions of Hall plateaus.\nHere we report a third type of the integer quantum Hall effect. Charge carriers\nin bilayer graphene have a parabolic energy spectrum but are chiral and exhibit\nBerry's phase 2pi affecting their quantum dynamics. The Landau quantization of\nthese fermions results in plateaus in Hall conductivity at standard integer\npositions but the last (zero-level) plateau is missing. The zero-level anomaly\nis accompanied by metallic conductivity in the limit of low concentrations and\nhigh magnetic fields, in stark contrast to the conventional, insulating\nbehavior in this regime. The revealed chiral fermions have no known analogues\nand present an intriguing case for quantum-mechanical studies."
    },
    {
        "anchor": "Optical identification using imperfections in 2D materials: The ability to uniquely identify an object or device is important for\nauthentication. Imperfections, locked into structures during fabrication, can\nbe used to provide a fingerprint that is challenging to reproduce. In this\npaper, we propose a simple optical technique to read unique information from\nnanometer-scale defects in 2D materials. Flaws created during crystal growth or\nfabrication lead to spatial variations in the bandgap of 2D materials that can\nbe characterized through photoluminescence measurements. We show a simple setup\ninvolving an angle-adjustable transmission filter, simple optics and a CCD\ncamera can capture spatially-dependent photoluminescence to produce complex\nmaps of unique information from 2D monolayers. Atomic force microscopy is used\nto verify the origin of the optical signature measured, demonstrating that it\nresults from nanometer-scale imperfections. This solution to optical\nidentification with 2D materials could be employed as a robust security measure\nto prevent counterfeiting.",
        "positive": "Enhanced current quantization in high frequency electron pumps in a\n  perpendicular magnetic field: We present experimental results of high frequency quantized charge pumping\nthrough a quantum dot formed by the electric field arising from applied\nvoltages in a GaAs/AlGaAs system in the presence of a perpendicular magnetic\nfield B. Clear changes are observed in the quantized current plateaus as a\nfunction of applied magnetic field. We report on the robustness in the length\nof the quantized plateaus and improvements in the quantization as a result of\nthe applied B field."
    },
    {
        "anchor": "A Density Matrix Renormalization Group Method Study of Optical\n  Properties of Porphines and Metalloporphines: The symmetrized Density-Matrix-Renormalization-Group (DMRG) method is used to\nstudy linear and nonlinear optical properties of Free base porphine and\nmetallo-porphine. Long-range interacting model, namely, Pariser-Parr-Pople\n(PPP) model is employed to capture the quantum many body effect in these\nsystems. The non-linear optical coefficients are computed within correction\nvector method. The computed singlet and triplet low-lying excited state\nenergies and their charge densities are in excellent agreement with\nexperimental as well as many other theoretical results. The rearrangement of\nthe charge density at carbon and nitrogen sites, on excitation, is discussed.\nFrom our bond order calculation, we conclude that porphine is well described by\nthe 18-annulenic structure in the ground state and the molecule expands upon\nexcitation. We have modelled the regular metalloporphine by taking an effective\nelectric field due to the metal ion and computed the excitation spectrum.\nMetalloporphines have $D_{4h}$ symmetry and hence have more degenerate excited\nstates. The ground state of Metalloporphines show 20-annulenic structure, as\nthe charge on the metal ion increases. The linear polarizability seems to\nincrease with the charge initially and then saturates. The same trend is\nobserved in third order polarizability coefficients.",
        "positive": "Far-field heat and angular momentum radiation of the Haldane model: We investigate the radiation of energy and angular momentum from 2D\ntopological systems with broken inversion symmetry and time reversal symmetry.\nA general theory of far-field radiation is developed using the linear response\nof 2D materials to the fluctuational electromagnetic field. Applying the theory\nto the Haldane model, we verify that the heat radiation complies with Planck's\nlaw only at low temperature and deviates from it as temperature becomes high.\nAngular momentum radiation is possible for this system and exhibits saturation\nas temperature increases. Parameters crucial to the radiation are investigated\nand optimized. This research enlightens the possibility of transposing the\nquantum information to the angular momentum degree of freedom."
    },
    {
        "anchor": "DC Transformer and DC Josephson(-like) Effects in Quantum Hall Bilayers: In the early days of superconductivity, Ivar Giaver discovered that it was\npossible to make a novel DC transformer by using one superconductor to drag\nvortices through another. An analogous effect was predicted to exist in quantum\nHall bilayers and has recently been discovered experimentally by Eisenstein's\ngroup at Caltech. Similarly, new experiments from the Caltech group have\ndemonstrated the existence of a Josephson-like `supercurrent' branch for\nelectrons coherently tunnelling between the two layers.",
        "positive": "Electronic Properties of Single Prussian Blue Analog Nanocrystals\n  Determined by Conductive-AFM: We report a study of the electron transport (ET) properties at the nanoscale\n(conductive-AFM noted C-AFM thereafter) of individual Prussian Blue Analog\n(PBA) cubic nanocrystals (NCs) of CsCo(III)Fe(II), with size between 15 and 50\nnm deposited on HOPG. We demonstrate that these PBA NCs feature an almost size\nindependent electron injection barriers of 0.41 +/- 0.02 eV and 0.27 +/- 0.03\neV at the CsCo(III)Fe(II)/HOPG and CsCo(III)Fe(II)/C-AFM tip, respectively, and\nan intrinsic electron conductivity evolving from largely dispersed between ca.\n5E-4 and 2E-2 S/cm without a clear correlation with the nanocrystal size. The\nconductivity values measured on individual nanocrystals are higher by up to 5\ndecades than those reported on PBA films."
    },
    {
        "anchor": "On-demand entanglement generation using dynamic single-electron sources: We review our recent proposals for the on-demand generation of entangled\nfew-electron states using dynamic single-electron sources. The generation of\nentanglement can be traced back to the single-electron entanglement produced by\nquantum point contacts acting as electronic beam splitters. The coherent\npartitioning of a single electron leads to entanglement between the two\noutgoing arms of the quantum point contact. We describe our various approaches\nfor generating and certifying entanglement in dynamic electronic conductors and\nwe quantify the influence of detrimental effects such as finite electronic\ntemperatures and other dephasing mechanisms. The prospects for future\nexperiments are discussed and possible avenues for further developments are\nidentified.",
        "positive": "Quantum Anomalous Hall Effect in Magnetic Doped Topological Insulators\n  and Ferromagnetic Spin-Gapless Semiconductors -- A Perspective Review: Quantum anomalous Hall effect, with a trademark of dissipationless chiral\nedge states for electronics/spintronics transport applications, can be realized\nin materials with large spin-orbit coupling and strong intrinsic magnetization.\nAfter Haldane seminal proposal, several models have been presented to\ncontrol/enhance the spin-orbit coupling and intrinsic magnetic exchange\ninteraction. After brief introduction of Haldane model for spineless fermions,\nfollowing three fundamental quantum anomalous Hall models are discussed in this\nperspective review: (i) low-energy effective four band model for magnetic-doped\ntopological insulator (Bi,Sb)2Te3 thin films, (ii) four band tight-binding\nmodel for graphene with magnetic adatoms, and (iii) two (three) band spinfull\ntight-binding model for ferromagnetic spin-gapless semiconductors with\nhoneycomb (kagome) lattice where ground state is intrinsically ferromagnetic.\nThese models cover two-dimensional Dirac materials hosting spinless, spinful\nand spin-degenerate Dirac points where various mass terms open a band gap and\nlead to quantum anomalous Hall effect. With emphasize on the topological phase\ntransition driven by ferromagnetic exchange interaction and its interplay with\nspin-orbit-coupling, we discuss various symmetry constraints on the nature of\nmass term and the materialization of these models. We hope this study will shed\nlight on the fundamental theoretical perspectives of quantum anomalous Hall\nmaterials."
    },
    {
        "anchor": "Thermally driven ballistic rectifer: The response of electric devices to an applied thermal gradient has, so far,\nbeen studied almost exclusively in two-terminal devices. Here we present\nmeasurements of the response to a thermal bias of a four-terminal,\nquasi-ballistic junction with a central scattering site. We find a novel\ntransverse thermovoltage measured across isothermal contacts. Using a\nmulti-terminal scattering model extended to the weakly non-linear voltage\nregime, we show that the device's response to a thermal bias can be predicted\nfrom its nonlinear response to an electric bias. Our approach forms a\nfoundation for the discovery and understanding of advanced, nonlocal,\nthermoelectric phenomena that in the future may lead to novel thermoelectric\ndevice concepts.",
        "positive": "Role of Dirac nodal lines and strain on the high spin Hall conductivity\n  of epitaxial IrO2 thin films: Since the discovery of a 'giant' spin Hall effect (SHE) in certain heavy\nmetal elements there has been an intense effort to identify and develop new and\ntechnologically viable, heavy-metal-based thin film materials that could\ngenerate spin currents with even greater efficiency to exert spin-orbit torques\n(SOT) on adjacent ferromagnetic nanostructures. In parallel, there have been\nwide ranging fundamental studies of the spin currents that can arise from\nrobust, intrinsic spin-orbit interaction (SOI) effects in more exotic systems\nincluding topological insulators, transition metal dichalcogenides with broken\ncrystalline symmetry, Weyl and Dirac semimetals where gapless electronic\nexcitations are protected by topology and symmetry. Here we experimentally\nstudy strong SOT from the topological semimetal IrO2 in (001) and (110) normal\nfilms, which exhibit distinctly different SHE strengths. Angle resolved\nphotoemission spectroscopy studies have shown IrO2 exhibits Dirac nodal lines\n(DNL) in the band structure, which could enable a very high spin Hall\nconductivity (SHC). The (001) films exhibit exceptionally high damping like\ntorque efficiency ranging from 0.45 at 293 K to 0.65 at 30 K which sets the\nlower bound of SHC that is ten times higher and of opposite sign than the\ntheoretical prediction. We observe a substantial reduction of SHC in\nanisotropically strained (110) films, which suggests that the DNLs that are\npresent in the (001) films and contribute to SHC, are disrupted and gapped due\nto the large anisotropic strain in (110) films, which in turn significantly\nlowers SHC. Very large value of SHC at room temperature of this Dirac semimetal\ncould be very promising for the practical application."
    },
    {
        "anchor": "Edge Theories for Polarized Quantum Hall States: Starting from recently proposed bosonic mean field theories for fully and\npartially polarized quantum Hall states, we construct corresponding effective\nlow energy theories for the edge modes. The requirements of gauge symmetry and\ninvariance under global O(3) spin rotations, broken only by a Zeeman coupling,\nimply boundary conditions that allow for edge spin waves. In the generic case,\nthese modes are chiral, and the spin stiffness differs from that in the bulk.\nFor the case of a fully polarized $\\nu=1$ state, our results agree with\nprevious Hartree-Fock calculations.",
        "positive": "Persistent current-carrying state of charge quasuparticles in\n  $np$-ribbon featuring single Dirac cone: The formation of persistent charge currents in mesoscopic systems remains an\ninteresting and actual topic of condensed matter research. Here, we analyze the\nformation of spontaneous arising persistent currents of charged fermions in\n2-dimensional electron-hole ribbons on the top and bottom of a 3-dimensional\ntopological insulator. In such a device the two-dimensional Dirac fermions with\nopposite chiralities are spatially separated that allows these currents to flow\nin the opposite directions without compensating each other. The nature of this\nphenomenon is based on the interference of the quasiparticle quantum waves\nwhich are scattered with asymmetric scattering phases at the lateral n-p chiral\njunction and then reflected back by the external boundaries of the ribbon. As a\nresult quasiparticles in the ribbon are shown to be in unified electron-hole\nquantum states carrying the persistent current."
    },
    {
        "anchor": "Magnitude of Magnetic Field Dependence of a Possible Selective Spin\n  Filter in ZnSe/Zn_{1-x}Mn_{x}Se Multilayer Heterostructure: Spin-polarized transport through a band-gap-matched ZnSe/Zn_{1-x}Mn_{x}\nSe/ZnSe/Zn_{1-x}Mn_{x}Se/ZnSe multilayer structure is investigated. The\nresonant transport is shown to occur at different energies for different spins\nowing to the split of spin subbands in the paramagnetic layers. It is found\nthat the polarization of current density can be reversed in a certain range of\nmagnetic field, with the peak of polarization moving towards a stronger\nmagnetic field for increasing the width of central ZnSe layer while shifting\ntowards an opposite direction for increasing the width of paramagnetic layer.\nThe reversal is limited in a small-size system. A strong suppression of the\nspin up component of the current density is present at high magnetic field. It\nis expected that such a reversal of the polarization could act as a possible\nmechanism for a selective spin filter device.",
        "positive": "Thin films thickness Measurement by the conductivity theory in the\n  framework of born approximation: When the thickness of the layer is smaller than the electrons mean free path,\nthe morphology affects the conductivity directly based on the layer thickness.\nThis issue provides basis in order to estimate the thickness of the layer by\nunderstanding the morphology and the value of the conductivity. This method is\nan inverse approach on thickness estimation and is applied to various samples.\nThe comparison of the results with other thickness estimations shows good\nconsistency. The benefits of this approach is that the only parameter that\nneeds to be measured is the conductivity, which is quite trivial. Despite the\nsimplicity of this approach, its results would prove adequate to study both the\nmaterial properties and the morphology of the layer. In addition, the\npossibility of repeating the measurements on thickness for AC currents with\nvarious frequencies enables averaging the measurements in order to obtain the\nmost precise results."
    },
    {
        "anchor": "Illustration of spin-half wave-functions, and other fractional-spin\n  structures: We provide an illustration of a geometric structure that exhibits the\nspin-half wave-function characteristics, namely that its full rotation displays\na phase inversion. We show that general fractional-spin geometric structures\nare possible, along with sketchy discussions concerning group-theoretical and\nquantum descriptions, as well as pose some queries. Synthesis of a\n$(PF_3)_n$-chain polymer in the form of a twisted ring is proposed as a\nrealization of a quazi-spin-1/3 structure.",
        "positive": "A Monolithic Topologically Protected Phononic Circuit: Precise control of elastic waves in modes and coherences is of great use in\nreinforcing nowadays elastic energy harvesting/storage, nondestructive testing,\nwave-mater interaction, high sensitivity sensing and information processing,\netc. All these implementations are expected to have elastic transmission with\nlower transmission losses and higher degree of freedom in transmission path.\nInspired by topological states of quantum matters, especially quantum spin Hall\neffects (QSHEs) providing passive solutions of unique disorder-immune surface\nstates protected by underlying nontrivial topological invariants of the bulk,\nthus solving severe performance trade-offs in experimentally realizable\ntopologically ordered states. Here, we demonstrate experimentally the first\nelastic analogue of QSHE, by a concise phononic crystal plate with only\nperforated holes. Strong elastic spin-orbit coupling is realized accompanied by\nthe first topologically-protected phononic circuits with both robustness and\nnegligible propagation loss overcoming many circuit- and system-level\nperformance limits induced by scattering. This elegant approach in a monolithic\nsubstrate opens up the possibility of realizing topological materials for\nphonons in both static and time-dependent regimes, can be immediately applied\nto multifarious chip-scale devices with both topological protection and massive\nintegration, such as on-chip elastic wave-guiding, elastic splitter, elastic\nresonator with high quality factor, and even (pseudo-)spin filter."
    },
    {
        "anchor": "A Simple and Scalable Graphene Patterning Method and Its Application in\n  CdSe Nanobelt/Graphene Schottky Junction Solar Cells: We develop a simple and scalable graphene patterning method using\nelectron-beam or ultraviolet lithography followed by a lift-off process. This\nmethod, with the merits of: high pattern resolution and high alignment\naccuracy, free from additional etching or harsh process, universal to arbitrary\nsubstrates, compatible to Si microelectronic technology, can be easily applied\nto diverse graphene-based devices, especially in array-based applications,\nwhere large-scale graphene patterns are desired. We have applied this method to\nfabricate CdSe nanobelt (NB)/graphene Schottky junction solar cells, which have\npotential application in integrated nano-optoelectronic systems. Typical\nas-fabricated solar cell shows excellent photovoltaic behavior with an\nopen-circuit voltage of ~ 0.51 V, a short-circuit current density of ~ 5.75\nmA/cm2, and an energy conversion efficiency of ~1.25%. We attribute the high\nperformance of the cell to the as-patterned high-performance graphene, which\ncan form an ideal Schottky contact with CdSe NB. Our results suggest both the\ndeveloped graphene patterning method and the as-fabricated CdSe nanobelt\n(NB)/graphene Schottky junction solar cells have reachable application\nprospect.",
        "positive": "Collective dynamical skyrmions excitations in magnonic crystal: We investigate theoretically skyrmion magnonic crystal, i.e., the dynamics of\nthe magnetization in a chain of the ferromagnetic nanodots being in skyrmion\nmagnetic configuration. We show that collective excitations are possible to be\nobserved in the structure. We present the dispersion relation of the coupled\nskyrmions. It exhibit a periodical property in dependence on wave vector,\ncharacteristic feature of the band structure in magnonic crystals. Spatial\nanalysis of the magnetization amplitude associated with the magnonic bands\nconfirms type of the excited modes, as breathing and clockwise gyrotropic\ndynamical skyrmions. These high and low frequency excitations, propagate with\nnegative and positive group velocity, respectively, and can be explored for\nstudy fundamental properties and technological applications in spintronics and\nmagnonics."
    },
    {
        "anchor": "Ballistic transport, chiral anomaly and emergence of the neutral\n  electron - hole plasma in graphene: The process of coherent creation of particle - hole excitations by an\nelectric field in graphene is quantitatively described using a dynamic \"first\nquantized\" approach. We calculate the evolution of current density, number of\npairs and energy in ballistic regime using the tight binding model. The series\nin electric field strength $E$ up to third order in both DC and AC are\ncalculated. We show how the physics far from the two Dirac points enters\nvarious physical quantities in linear response and how it is related to the\nchiral anomaly. The third harmonic generation and the imaginary part of\nconductivity are obtained. It is shown that at certain time scale\n$t_{nl}\\propto E^{-1/2}$ the physical behaviour dramatically changes and the\nperturbation theory breaks down. Beyond the linear response physics is explored\nusing an exact solution of the first quantized equations. While for small\nelectric fields the I-V curve is linear characterized by the universal minimal\nresistivity $\\sigma =\\pi /2(e^{2}/h)$%, at $t>t_{nl}$ the conductivity grows\nfast. The copious pair creation (with rate $E^{3/2}$), analogous to Schwinger's\nelectron - positron pair creation from vacuum in QED, leads to creation of the\nelectron - hole plasma at ballistic times of order $t_{nl}$. This process is\nterminated by a relaxational recombination.",
        "positive": "Ripples in a graphene membrane coupled to Glauber spins: We propose a theory of ripples in suspended graphene sheets based on\ntwo-dimensional elasticity equations that are made discrete on the honeycomb\nlattice and then periodized. At each point carbon atoms are coupled to Ising\nspins whose values indicate the atoms local trend to move vertically off-plane.\nThe Ising spins are in contact with a thermal bath and evolve according to\nGlauber dynamics. In the limit of slow spin flip compared to membrane\nvibrations, ripples with no preferred orientation appear as long-lived\nmetastable states for any temperature. Numerical solutions confirm this\npicture."
    },
    {
        "anchor": "Surface effects on ionic Coulomb blockade in nanometer-size pores: Ionic Coulomb blockade in nanopores is a phenomenon that shares some\nsimilarities but also differences with its electronic counterpart. Here, we\ninvestigate extensively this phenomenon using all-atom molecular dynamics of\nionic transport through nanopores of about one nanometer in diameter and up to\nseveral nanometers in length. Our goal is to better understand the role of\natomic roughness and structure of the pore walls in the ionic Coulomb blockade.\nOur numerical results reveal the following general trends. First, the nanopore\nselectivity changes with its diameter, and the nanopore position in the\nmembrane influences the current strength. Second, the ionic transport through\nthe nanopore takes place in a hopping-like fashion over a set of discretized\nstates caused by local electric fields due to membrane atoms. In some cases,\nthis creates a slow-varying \"crystal-like\" structure of ions inside the\nnanopore. Third, while at a given voltage, the resistance of the nanopore\ndepends on its length, the slope of this dependence appears to be independent\nof the molarity of ions. An effective kinetic model that captures the ionic\nCoulomb blockade behavior observed in MD simulations is formulated.",
        "positive": "Realization of corner and helical edge states in topologically trivial\n  band gap by twig edge: The twig edge states in graphene-like structures are viewed as the fourth\nstates complementary to their zigzag, bearded, and armchair counterparts. In\nthis work, we study a rod-in-plasma system in honeycomb lattice with twig edges\nunder external magnetic fields and lattice scaling and show that twig edge\nstates can exist in different phases of the system, such as quantum Hall phase,\nquantum spin Hall phase and insulating phase. The twig edge states in the\nquantum Hall phase exhibit robust one-way transmission property immune to\nbackscattering and thus provide a novel avenue for solving the plasma\ncommunication blackout problem. Moreover, we demonstrate that corner and edge\nstates can exist within the trivial band gap of the insulating phase by\nmodulating the on-site potential of the twig edges. Especially, helical edge\nstates with the unique feature of pseudospin-momentum locking that could be\nexited by chiral sources are demonstrated at the twig edges within the trivial\nband gap. Our results show that many topological-like behaviors of\nelectromagnetic waves are not necessarily tied to the exact topology of the\nsystems and the twig edges and interface engineering can bring new\nopportunities for more flexible manipulation of electromagnetic waves."
    },
    {
        "anchor": "Experimental Evidence of a Directed-Flux Phase of Condensed Matter: We demonstrate experimentally that in an asymmetric quantum well in presence\nof quantizing magnetic field tilted in XZ plane, confining potential V(z) lifts\nLandau level degeneracy related to position of the centers of electron\ncyclotron orbits along X axis. This results in a transformation of the Landau\nlevels into the bands in which the electrons may possess nonzero directed\nvelocity along Y axis. We directly demonstrate that the electrons are spatially\nseparated along X axis depending on their velocity along Y axis that means\nspontaneous one-dimensional electron fluxes flow in opposite directions along Y\naxis even within the fully occupied bands. We also directly demonstrate that\nthe electrons possess nonzero electric dipole moment as a result of Lorentz\nforce effect on these one-dimensional fluxes. On the basis of these experiments\nwe put forward the concept of a directed-flux phase of condensed matter.",
        "positive": "Nonlinear damping and dephasing in nanomechanical systems: We present a microscopic theory of nonlinear damping and dephasing of\nlow-frequency eigenmodes in nano- and micro-mechanical systems. The mechanism\nof the both effects is scattering of thermally excited vibrational modes off\nthe considered eigenmode. The scattering is accompanied by energy transfer of\n$2\\hbar\\omega_0$ for nonlinear damping and is quasieleastic for dephasing. We\ndevelop a formalism that allows studying both spatially uniform systems and\nsystems with a strong nonuniformity, which is smooth on the typical wavelength\nof thermal modes but not their mean free path. The formalism accounts for the\ndecay of thermal modes, which plays a major role in the nonlinear damping and\ndephasing. We identify the nonlinear analogs of the Landau-Rumer,\nthermoelastic, and Akhiezer mechanisms and find the dependence of the\nrelaxation parameters on the temperature and the geometry of a system."
    },
    {
        "anchor": "Tuning Rashba spin-orbit coupling in homogeneous semiconductor nanowires: We use $\\vec{k}\\cdot\\vec{p}$ theory to estimate the Rashba spin-orbit\ncoupling (SOC) in large semiconductor nanowires. We specifically investigate\nGaAs- and InSb-based devices with different gate configurations to control\nsymmetry and localization of the electron charge density. We explore\ngate-controlled SOC for wires of different size and doping, and we show that in\nhigh carrier density SOC has a non-linear electric field susceptibility, due to\nlarge reshaping of the quantum states. We analyze recent experiments with InSb\nnanowires in light of our calculations. Good agreement is found with SOC\ncoefficients reported in Phys. Rev.B 91, 201413(R) (2015), but not with the\nmuch larger values reported in Nat Commun., 8, 478 (2017). We discuss possible\norigins of this discrepancy.",
        "positive": "Hyperfine interaction in a quantum dot: Non-Markovian electron spin\n  dynamics: We have performed a systematic calculation for the non-Markovian dynamics of\na localized electron spin interacting with an environment of nuclear spins via\nthe Fermi contact hyperfine interaction. This work applies to an electron in\nthe s -type orbital ground state of a quantum dot or bound to a donor impurity,\nand is valid for arbitrary polarization p of the nuclear spin system, and\narbitrary nuclear spin I in high magnetic fields. In the limit of p=1 and\nI=1/2, the Born approximation of our perturbative theory recovers the exact\nelectron spin dynamics. We have found the form of the generalized master\nequation (GME) for the longitudinal and transverse components of the electron\nspin to all orders in the electron spin--nuclear spin flip-flop terms. Our\nperturbative expansion is regular, unlike standard time-dependent perturbation\ntheory, and can be carried-out to higher orders. We show this explicitly with a\nfourth-order calculation of the longitudinal spin dynamics. In zero magnetic\nfield, the fraction of the electron spin that decays is bounded by the\nsmallness parameter \\delta=1/p^{2}N, where N is the number of nuclear spins\nwithin the extent of the electron wave function. However, the form of the decay\ncan only be determined in a high magnetic field, much larger than the maximum\nOverhauser field. In general the electron spin shows rich dynamics, described\nby a sum of contributions with non-exponential decay, exponential decay, and\nundamped oscillations. There is an abrupt crossover in the electron spin\nasymptotics at a critical dimensionality and shape of the electron envelope\nwave function. We propose a scheme that could be used to measure the\nnon-Markovian dynamics using a standard spin-echo technique, even when the\nfraction that undergoes non-Markovian dynamics is small."
    },
    {
        "anchor": "Transport through Double-Dots coupled to normal and superconducting\n  leads: We study transport through double quantum dots coupled to normal and\nsuperconducting leads, where the Andreev reflection plays a key role in\ndetermining characteristic transport properties. We shall discuss two typical\ncases, i.e. double dots with serial or parallel geometry. For the parallel\ngeometry, the interference of electrons via multiple paths is induced, so that\nthe transmission probability has Fano-type dip structures which are symmetric\nwith respect to the Fermi energy. We also investigate the Aharonov-Bohm(AB)\neffect for the parallel geometry. In some particular situations, we find that\nthe general AB period for double dots, 4$\\pi$, is reduced to 2$\\pi$.",
        "positive": "Probing the Shape of Quantum Dots with Magnetic Fields: A tool for the identification of the shape of quantum dots is developed. By\npreparing a two-electron quantum dot, the response of the low-lying excited\nstates to a homogeneous magnetic field, i.e. their spin and parity\noscillations, is studied for a large variety of dot shapes. For any geometric\nconfiguration of the confinement we encounter characteristic spin singlet -\ntriplet crossovers. The magnetization is shown to be a complementary tool for\nprobing the shape of the dot."
    },
    {
        "anchor": "How do edge states position themselves in a quantum Hall graphene pn\n  junction?: Recent experiments have shown that electronic Mach-Zehnder interferometers of\nunprecedented fidelities could be built using a graphene pn junction in the\nquantum Hall regime. In these junctions, two different edge states\ncorresponding to two different valley configurations are spatially separated\nand form the two arms of the interferometer. The observed separation, of\nseveral tens of nanometers, has been found to be abnormally high and thus\nassociated to unrealistic values of the exchange interaction. In this work, we\nshow that, although the separation is due to exchange interaction, its actual\nvalue is entirely governed by the sample geometry and independent of the value\nof the exchange splitting. Our analysis follows the lines of the classical work\nof Chklovski-Shklovskii- Glazman on electrostatically induced edge state\nreconstruction and includes quantitative numerical calculations in the\nexperimental geometries.",
        "positive": "Theory of intraband plasmons in doped carbon nanotubes: rolled\n  surface-plasmons of graphene: A single-wall carbon nanotube possesses two different types of plasmons\nspecified by the wavenumbers in the azimuthal and axial directions. The\nazimuthal plasmon that is caused by interband transitions has been studied,\nwhile the effect of charge doping is unknown. In this paper, we show that when\nnanotubes are heavily doped, intraband transitions cause the azimuthal plasmons\nto appear as a plasmon resonance in the near-infrared region of the absorption\nspectra, which is absent for light doping due to the screening effect. The\naxial plasmons that are inherent in the cylindrical waveguide structures of\nnanotubes, account for the absorption peak of the metallic nanotube observed in\nthe terahertz region. The excitation of axial (azimuthal) plasmons requires a\nlinearly polarized light parallel (perpendicular) to the tube's axis."
    },
    {
        "anchor": "Graphene nanoribbon based spaser: A novel type of spaser with the net amplification of surface plasmons (SPs)\nin doped graphene nanoribbon is proposed. The plasmons in THz region can be\ngenerated in a dopped graphene nanoribbon due to nonradiative excitation by\nemitters like two level quantum dots located along a graphene nanoribbon. The\nminimal population inversion per unit area, needed for the net amplification of\nSPs in a doped graphene nanoribbon is obtained. The dependence of the minimal\npopulation inversion on the surface plasmon wavevector, graphene nanoribbon\nwidth, doping and damping parameters necessary for the amplification of surface\nplasmons in the armchair graphene nanoribbon is studied.",
        "positive": "Magnetization reversals in a disk-shaped small magnet with an interface: We consider a nanodisk possessing two coupled materials with different\nferromagnetic exchange constant. The common border line of the two media passes\nat the disk center dividing the system exactly in two similar half-disks. The\nvortex core motion crossing the interface is investigated with a simple\ndescription based on a two-dimensional model which mimics a very thin real\nmaterial with such a line defect. The main result of this study is that,\ndepending on the magnetic coupling which connects the media, the vortex core\ncan be dramatically and repeatedly flipped from up to down and vice versa by\nthe interface. This phenomenon produces burst-like emission of spin waves each\ntime the switching process takes place."
    },
    {
        "anchor": "Optical remote control of a charge qubit: Both the electron transport-based qubits, implemented through double quantum\ndots, and the sources of indistinguishable single-photons like self-assembled\nquantum dots are strong candidates for the implementation of quantum\ntechnologies, such as quantum computers and quantum repeaters. Here, we\ndemonstrate a reliable way of coupling these two types of qubits, uncovering\nthe possibility of controlling and reading out the population of the double\nquantum dot via optical excitation. It is also showed that, in spite of the\ndecoherence mechanisms affecting the qubits, the entanglement between them is\nachievable and, consequently, the implementation of the suggested system in\nquantum technologies is feasible.",
        "positive": "Electronic and magnetic properties of FeSe$_{0.5}$Te$_{0.5}$ : A\n  first-principles study: The atomic structures, electronic band structures and magnetic properties of\nmonolayer FeSe and FeSe$_{0.5}$Te$_{0.5}$ of different configurations have been\nsystematically investigated via first-principles calculations with the\ninclusion of spin-orbit coupling (SOC). Three different antiferromagnetic (AFM)\norders, including checkerboard order, collinear order and pair-checkerboard\norder, as well as paramagnetic state have been explored. In monolayer FeSe,\ncollinear AFM order is found to be the most stable order, in accordance with\nprevious investigations. Substituting half Se atoms with Te atoms, the\npair-checkerboard AFM order is the ground-state magnetic order in\nFeSe$_{0.5}$Te$_{0.5}$. Both AFM-ordered FeSe and FeSe$_{0.5}$Te$_{0.5}$ have\nDirac-cone-like band structures. SOC has a great influence on the band\nstructures at the Dirac cone. The direction of the magnetic moments (in-plane\nor out-of-plane) directly determines whether the Dirac cone could be opened by\nSOC, and the gap values also relate to the specific magnetic structure.\nAlthough SOC is stronger in FeSe$_{0.5}$Te$_{0.5}$, the SOC-induced band gaps\nare either only slightly enlarged or even much shrunk compared with those gaps\nin FeSe. Due to the symmetry breaking brought by Te-substitution, the band\nstructures of FeSe$_{0.5}$Te$_{0.5}$ have a new feature of combined\nRashba-Dresselhaus splitting. Our results have provided a comprehensive study\non the magnetic property of FeSe$_{0.5}$Te$_{0.5}$, which may help to\nunderstand the relation between magnetism and the superconductivity in the\nhigh-Tc monolayer superconductor."
    },
    {
        "anchor": "Optoelectronic device simulations based on macroscopic Maxwell-Bloch\n  equations: Due to their intuitiveness, flexibility and relative numerical efficiency,\nthe macroscopic Maxwell-Bloch (MB) equations are a widely used semiclassical\nand semi-phenomenological model to describe optical propagation and coherent\nlight-matter interaction in media consisting of discrete-level quantum systems.\nThis review focuses on the application of this model to advanced optoelectronic\ndevices, such as quantum cascade and quantum dot lasers. The Bloch equations\nare here treated as a density matrix model for driven quantum systems with two\nor multiple discrete energy levels, where dissipation is included by Lindblad\nterms. Furthermore, the one-dimensional MB equations for semiconductor\nwaveguide structures and optical fibers are rigorously derived. Special\nanalytical solutions and suitable numerical methods are presented. Due to the\nimportance of the MB equations in computational electrodynamics, an emphasis is\nplaced on the comparison of different numerical schemes, both with and without\nthe rotating wave approximation. The implementation of additional effects which\ncan become relevant in semiconductor structures, such as spatial hole burning,\ninhomogeneous broadening and local-field corrections, is discussed. Finally,\nlinks to microscopic models and suitable extensions of the Lindblad formalism\nare briefly addressed.",
        "positive": "Anisotropic ultrafast optical response of terahertz pumped graphene: We have measured the ultrafast anisotropic optical response of highly doped\ngraphene to an intense single cycle terahertz pulse. The time profile of the\nterahertz-induced anisotropy signal at 800 nm has minima and maxima repeating\nthose of the pump terahertz electric field modulus. It grows with increasing\ncarrier density and demonstrates a specific nonlinear dependence on the\nelectric field strength. To describe the signal, we have developed a\ntheoretical model that is based on the energy and momentum balance equations\nand takes into account optical phonons of graphene and substrate. According to\nthe theory, the anisotropic response is caused by the displacement of the\nelectronic momentum distribution from zero momentum induced by the pump\nelectric field in combination with polarization dependence of the matrix\nelements of interband optical transitions."
    },
    {
        "anchor": "Interfacial and bulk spin Hall contributions to field-like spin-orbit\n  torque generated by Iridium: We present measurements of spin orbit torques generated by Ir as a function\nof film thickness in sputtered Ir/CoFeB and Ir/Co samples. We find that Ir\nprovides a damping-like component of spin orbit torque with a maximum spin\ntorque conductivity 1.4e5 in SI unit and a maximum spin-torque efficiency of\n0.04, which is sufficient to drive switching in an 0.8 nm film of CoFeB with\nperpendicular magnetic anisotropy. We also observe a surprisingly large field\nlike spin orbit torque. Measurements as a function of Ir thickness indicate a\nsubstantial contribution to the FLT from an interface mechanism so that in the\nultrathin limit there is a non-zero FLT with a maximum torque conductivity\n-5.0E4 in the SI unit. When the Ir film thickness becomes comparable to or\ngreater than its spin diffusion length, 1.6 nm, there is also a smaller bulk\ncontribution to the fieldlike torque.",
        "positive": "Macroscopic Quantum Tunneling of a Topological Ferromagnet: The recent advent of topological states of matter spawned many significant\ndiscoveries. The quantum anomalous Hall effect[1-3] is a prime example due to\nits potential for applications in quantum metrology[4, 5] as well as its\ninfluence on fundamental research into the underlying topological and magnetic\nstates[6-11] and axion electrodynamics[2, 12-14]. Here, we perform electronic\ntransport studies on a (V,Bi,Sb)2Te3 ferromagnetic topological insulator\nnanostructure in the quantum anomalous Hall regime. This allows us access to\nthe dynamics of an individual ferromagnetic domain. The volume of the domain is\nestimated to be about 85 000 nm3, containing some 50 000 vanadium atoms, spread\nover a macroscopic distance of 115 nm. Telegraph noise resulting from the\nmagnetization fluctuations of this domain is observed in the Hall signal.\nCareful analysis of the influence of temperature and external magnetic field on\nthe domain switching statistics provides evidence for quantum tunneling of\nmagnetization[15-22] in a macrospin state. This ferromagnetic macrospin is not\nonly the largest magnetic object in which quantum tunneling has been observed,\nbut also the first observation of the effect in a topological state of matter."
    },
    {
        "anchor": "Bulk Spectrum and K-theory for Infinite-Area Topological Quasicrystal: The bulk spectrum of a possible Chern insulator on a quasicrystalline lattice\nis examined. The effect of being a 2D insulator seems to override any fractal\nproperties in the spectrum. We compute that the spectrum is either two\ncontinuous bands, or that any gaps other than the main gap are small. After\nmaking estimates on the spectrum, we deduce a finite system size, above which\nthe K-theory must coincide with the K-theory of the infinite system. Knowledge\nof the spectrum and $K$-theory of the infinite-area system will control the\nspectrum and K-theory of sufficiently large finite systems.\n  The relation between finite volume $K$-theory and infinite volume Chern\nnumbers is only proven to begin, for the model under investigation here, for\nsystems on Hilbert space of dimension around 17 million. The real-space method\nbased on the Clifford spectrum allows for computing Chern numbers for systems\non Hilbert space of dimension around 2.7 million. New techniques in numerical\nK-theory are used to equate the K-theory of systems of different sizes.",
        "positive": "Coulomb Effects and Electron Transport Through a Coherent Conductor: We analyze electron transport through relatively short coherent conductors in\nthe presence of Coulomb interaction. We evaluate the current-voltage\ncharacteristics of such conductors taking into account the effect of an\nexternal environment. Within our model, at large conductances and low $T$ the\nconductance is suppressed by a universal factor which depends only on the type\nof the conductor. We also argue that at T=0 the system ``scatterer+shunt'' can\nbe either an insulator or a metal depending on whether its total resistance is\nlarger or smaller than $R_Q=h/e^2\\approx 25.8$ k$\\Omega$. In a metallic phase\nthe Coulomb gap is fully suppressed by quantum fluctuations."
    },
    {
        "anchor": "Transport through single-level quantum dot in a magnetic field: We study the effect of an external magnetic field on the transport properties\nof a quantum dot using a recently developed extension of the functional\nrenormalization group approach to non-equilibrium situations. We discuss in\nparticular the interplay and competition of the different energy scales of the\ndot and the magnetic field on the stationary non-equilibrium current and\nconductance. As rather interesting behavior we find a switching behavior of the\nmagnetic field for intermediate correlations and bias voltage.",
        "positive": "Plasmonic nanocrystals with complex shapes for photocatalysis and\n  growth: Contrasting anisotropic hot-electron generation with the photothermal\n  effect: In plasmonics, and particularly in plasmonic photochemistry, the effect of\nhot-electron generation is an exciting phenomenon driving new fundamental and\napplied research. However, obtaining a microscopic description of the\nhot-electron states represents a challenging problem, limiting our capability\nto design efficient nanoantennas exploiting these excited carriers. This paper\naddresses this limitation and studies the spatial distributions of the\nphotophysical dynamic parameters controlling the local surface photochemistry\non a plasmonic nanocrystal. We found that the generation of energetic electrons\nand holes in small plasmonic nanocrystals with complex shapes is strongly\nposition-dependent and anisotropic, whereas the phototemperature across the\nnanocrystal surface is nearly uniform. Our formalism includes three mechanisms\nfor the generation of excited carriers: the Drude process, the surface-assisted\ngeneration of hot-electrons in the sp-band, and the excitation of interband\nd-holes. Our computations show that the hot-carrier generation originating from\nthese mechanisms reflects the internal structure of hot spots in nanocrystals\nwith complex shapes. The injection of energetic carriers and increased surface\nphototemperature are driving forces for photocatalytic and photo-growth\nprocesses on the surface of plasmonic nanostructures. Therefore, developing a\nconsistent microscopic theory of such processes is necessary for designing\nefficient nanoantennas for photocatalytic applications."
    },
    {
        "anchor": "$\\textit{Ab initio}$ four-band Wannier tight-binding model for generic\n  twisted graphene systems: The newly realized twisted graphene systems such as twisted bilayer graphene\n(TBG), twisted double bilayer graphene (TDBG), and twisted trilayer graphene\n(TTG) have attracted widespread theoretical attention. Therefore, a simple and\naccurate model of the systems is of vital importance for the further study.\nHere, we construct the symmetry-adapted localized Wannier functions and the\ncorresponding $\\textit{ab initio}$ minimal two-valley four-band effective\ntight-binding models for generic twisted graphene systems with small twist\nangle. Such two-valley model evades the Wannier obstruction caused by the\nfragile topology in one-valley model. The real space valley operator is\nintroduced to explicitly describe the valley $U_{v}\\left(1\\right)$ symmetry.\nEach symmetry-adapted Wannier orbital shows a peculiar three-peak form with its\nmaximum at AA spots and its center at AB or BA spots. An extended Hubbard model\nis also given and the related parameters are presented explicitly. We provide\nan approach to systematically build the Wannier tight-binding model for generic\ntwisted graphene systems. Our model provides a firm basis for further study of\nthe many-body effects in these systems.",
        "positive": "Theory of electric-field-induced spin accumulation and spin current in\n  the two-dimensional Rashba model: Based on the spin-density-matrix approach, both the electric-field-induced\nspin accumulation and the spin current are systematically studied for the\ntwo-dimensional Rashba model. Eigenmodes of spin excitations give rise to\nresonances in the frequency domain. Utilizing a general and physically\nwell-founded definition of the spin current, we obtain results that differ\nremarkably from previous findings. It is shown that there is a close\nrelationship between the spin accumulation and the spin current, which is due\nto the prescription of a quasi-chemical potential and which does not result\nfrom a conservation law. Physical ambiguities are removed that plagued former\napproaches with respect to a spin-Hall current that is independent of the\nelectric field. For the clean Rashba model, the intrinsic spin-Hall\nconductivity exhibits a logarithmic divergency in the low-frequency regime."
    },
    {
        "anchor": "Magnon-driven longitudinal spin Seebeck effect in F|N and N|F|N\n  structures: role of asymmetric in-plane magnetic anisotropy: The influence of an asymmetric in-plane magnetic anisotropy on the thermally\nactivated spin current is studied theoretically for two different systems; (i)\nthe system consisting of a ferromagnetic insulator in a direct contact with a\nnonmagnetic metal, and the sandwich structure consisting of a ferromagnetic\ninsulating part sandwiched between two nonmagnetic metals. It is shown that\nwhen the difference between the temperatures of the two nonmagnetic metals in a\nstructure is not large, the spin pumping currents from the magnetic part to the\nnonmagnetic ones are equal in amplitude and have opposite directions, so only\nthe spin torque current contributes to the total spin current. The spin current\nflows then from the nonmagnetic metal with the higher temperature to the\nnonmagnetic metal having a lower temperature. Its amplitude varies linearly\nwith the difference in temperatures. In addition, we have found that if the\nmagnetic anisotropy is in the layer plane, then the spin current increases with\nthe magnon temperature, while in the case of an out-of-plane magnetic\nanisotropy the spin current decreases when the magnon temperature enhances.\nEnlarging the difference between the temperatures of the nonmagnetic metals,\nthe linear response becomes important, as confirmed by analytical expressions\ninferred from the Fokker-Planck approach and by the results obtained upon a\nfull numerical integration of the stochastic Landau-Lifshitz-Gilbert equation.",
        "positive": "Scanning Tunneling Potentiometry, Charge Transport and Landauer's\n  Resistivity Dipole from the Quantum to the Classical Transport Regime: Using the non-equilibrium Keldysh formalism, we investigate the spatial\nrelation between the electro-chemical potential measured in scanning tunneling\nspectroscopy, and local current patterns over the entire range from the quantum\nto the classical transport regime. These quantities show similar spatial\npatterns near the quantum limit, but are related by Ohm's law only in the\nclassical regime. We demonstrate that defects induce a Landauer residual\nresistivity dipole in the electro-chemical potential with the concomitant\nspatial current pattern representing the field lines of the dipole."
    },
    {
        "anchor": "Indirect exchange interaction between magnetic impurities in the\n  two-dimensional topological insulator based on CdTe/HgTe/CdTe quantum wells: We study indirect exchange interaction between magnetic impurities in the\n(001) CdTe/HgTe/CdTe symmetric quantum well. We consider low temperatures and\nthe case of the chemical potential placed in the energy gap of the 2D\nquasiparticle spectrum. We find that the indirect exchange interaction is\nsuppressed exponentially with the distance between magnetic impurities. The\npresence of inversion asymmetry results in oscillations of the indirect\nexchange interaction with the distance and generates additional terms which are\nnon-invariant under rotations in the (001) plane. The indirect exchange\ninteraction matrix has complicated structure with some terms proportional to\nthe sign of the energy gap.",
        "positive": "Scattering induced spin orientation and spin currents in gyrotropic\n  structures: It is shown that additional contributions both to current-induced spin\norientation and to the spin Hall effect arise in quantum wells due to gyrotropy\nof the structures. Microscopically, they are related to basic properties of\ngyrotropic systems, namely, linear in the wave vector terms in the matrix\nelement of electron scattering and in the energy spectrum. Calculation shows\nthat in high-mobility structures the contribution to the spin Hall current\nconsidered here can exceed the term originated from the Mott skew scattering."
    },
    {
        "anchor": "Hydrodynamics in graphene: Linear-response transport: We develop a hydrodynamic description of transport properties in\ngraphene-based systems which we derive from the quantum kinetic equation. In\nthe interaction-dominated regime, the collinear scattering singularity in the\ncollision integral leads to fast unidirectional thermalization and allows us to\ndescribe the system in terms of three macroscopic currents carrying electric\ncharge, energy, and quasiparticle imbalance. Within this \"three-mode\"\napproximation we evaluate transport coeffcients in monolayer graphene as well\nas in double-layer graphene-based structures. The resulting classical\nmagnetoresistance is strongly sensitive to the interplay between the sample\ngeometry and leading relaxation processes. In small, mesoscopic samples the\nmacroscopic currents are inhomogeneous which leads to linear magnetoresistance\nin classically strong fields. Applying our theory to double-layer\ngraphene-based systems, we provide microscopic foundation for phenomenological\ndescription of giant magnetodrag at charge neutrality and find magnetodrag and\nHall drag in doped graphene.",
        "positive": "Numerically exact counting statistics of energy current in the Kondo\n  regime: We use the inchworm Quantum Monte Carlo method to investigate the full\ncounting statistics of particle and energy currents in a strongly correlated\nquantum dot. Our method is used to extract the heat fluctuations and entropy\nproduction of a quantum thermoelectric device, as well as cumulants of the\nparticle and energy currents. The energy--particle current cross correlations\nreveal information on the preparation of the system and the interplay of\nthermal and electric currents. We furthermore demonstrate the signature of a\ncrossover from Coulomb blockade to Kondo physics in the energy current\nfluctuations, and show how the conventional master equation approach to full\ncounting statistics systematically fails to capture this crossover."
    },
    {
        "anchor": "Dissipation-induced enhancement and squeezing of quantum fluctuations: We study a quantum harmonic oscillator linearly coupled through the position\noperator $\\hat{q}$ to a first bath and through the momentum operator $\\hat{p}$\nto a second bath yielding an Ohmic-Drude dissipation. We analyse the\noscillator's fluctuations as a function of the ratio between the strength of\nthe two couplings, focusing in particular on the situation in which the two\ndissipative interactions are comparable. Analytic formulas are derived in the\nrelevant regimes corresponding to the low temperature limit and when the Drude\nhigh frequency cutoff is much larger than all other frequencies. At low\ntemperature, each bath operates to suppress the oscillator's ground state\nquantum fluctuations ${\\langle \\Delta \\hat{q}^2 \\rangle}_0$ or ${\\langle \\Delta\n\\hat{p}^2 \\rangle}_0$ appearing in the corresponding interaction. When one of\nthe two dissipative interactions dominates over the other, the fluctuations for\nthe coupling operator are squeezed. When the two interactions are comparable,\nthe two baths enter in competition as the two conjugate operators do not\ncommute yielding quantum frustration. In this regime, remarkably, the\nfluctuations of both two quadratures can be enhanced by increasing the\ndissipative coupling.",
        "positive": "Noise-induced collective quantum state preservation in spin qubit arrays: The hyperfine interaction with nuclear spins (or, Overhauser noise) has long\nbeen viewed as a leading source of decoherence in individual quantum dot spin\nqubits. Here we show that in a coupled multi-qubit system consisting of as few\nas four spins, interactions with nuclear spins can have the opposite effect\nwhere they instead preserve the collective quantum state of the system. This\nnoise-induced state preservation can be realized in a linear spin qubit array\nusing current technological capabilities. Our proposal requires no control over\nthe Overhauser fields in the array; only experimental control over the average\ninterqubit coupling between nearest neighbors is needed, and this is readily\nachieved by tuning gate voltages. Our results illustrate how the role of the\nenvironment can transform from harmful to helpful in the progression from\nsingle-qubit to multi-qubit quantum systems."
    },
    {
        "anchor": "Two-resonator circuit QED: A superconducting quantum switch: We introduce a systematic formalism for two-resonator circuit QED, where two\non-chip microwave resonators are simultaneously coupled to one superconducting\nqubit. Within this framework, we demonstrate that the qubit can function as a\nquantum switch between the two resonators, which are assumed to be originally\nindependent. In this three-circuit network, the qubit mediates a geometric\nsecond-order circuit interaction between the otherwise decoupled resonators. In\nthe dispersive regime, it also gives rise to a dynamic second-order\nperturbative interaction. The geometric and dynamic coupling strengths can be\ntuned to be equal, thus permitting to switch on and off the interaction between\nthe two resonators via a qubit population inversion or a shifting of the qubit\noperation point. We also show that our quantum switch represents a flexible\narchitecture for the manipulation and generation of nonclassical microwave\nfield states as well as the creation of controlled multipartite entanglement in\ncircuit QED. In addition, we clarify the role played by the geometric\ninteraction, which constitutes a fundamental property characteristic of\nsuperconducting quantum circuits without counterpart in quantum-optical\nsystems. We develop a detailed theory of the geometric second-order coupling by\nmeans of circuit transformations for superconducting charge and flux qubits.\nFurthermore, we show the robustness of the quantum switch operation with\nrespect to decoherence mechanisms. Finally, we propose a realistic design for a\ntwo-resonator circuit QED setup based on a flux qubit and estimate all the\nrelated parameters. In this manner, we show that this setup can be used to\nimplement a superconducting quantum switch with available technology.",
        "positive": "Electronic properties of gated triangular graphene quantum dots:\n  Magnetism, correlations, and geometrical effects: We present a theory of electronic properties of gated triangular graphene\nquantum dots with zigzag edges as a function of size and carrier density. We\nfocus on electronic correlations, spin and geometrical effects using a\ncombination of atomistic tight-binding, Hartree-Fock and configuration\ninteraction methods (TB+HF+CI) including long range Coulomb interactions. The\nsingle particle energy spectrum of triangular dots with zigzag edges exhibits a\ndegenerate shell at the Fermi level with a degeneracy N_{edge} proportional to\nthe edge size. We determine the effect of the electron-electron interactions on\nthe ground state, the total spin and the excitation spectrum as a function of a\nshell filling and the degeneracy of the shell using TB+HF+CI for N_{edge} < 12\nand approximate CI method for N_{edge}\\geq 12. For a half-filled neutral shell\nwe find spin polarized ground state for structures up to N=500 atoms in\nagreement with previous {\\it ab initio} and mean-field calculations, and in\nagreement with Lieb's theorem for a Hubbard model on a bipartite lattice.\nAdding a single electron leads to the complete spin depolarization for\nN_{edge}\\leq 9. For larger structures, the spin depolarization is shown to\noccur at different filling factors. Away from half-fillings excess\nelectrons(holes) are shown to form Wigner-like spin polarized triangular\nmolecules corresponding to large gaps in the excitation spectrum. The validity\nof conclusions is assessed by a comparison of results obtained from different\nlevels of approximations. While for the charge neutral system all methods give\nqualitatively similar results, away from the charge neutrality an inclusion of\nall Coulomb scattering terms is necessary to produce results presented here."
    },
    {
        "anchor": "Optimized micromagnet geometries for Majorana zero modes in low g-factor\n  materials: Solid-state experimental realizations of Majorana bound states are based on\nmaterials with strong intrinsic spin-orbit interactions. In this paper, we\nexplore an alternative approach where spin-orbit coupling is induced\nartificially through a nonuniform magnetic field that originates from an array\nof micromagnets. Using a recently developed optimization algorithm, we find\nsuitable magnet geometries for the emergence of topological superconductivity\nin wires without intrinsic spin-orbit coupling. We confirm the robustness of\nMajorana bound states against disorder and periodic potentials whose amplitudes\ndo not exceed the Zeeman energy. Furthermore, we identify low g-factor\nmaterials commonly used in mesoscopic physics experiments as viable candidates\nfor Majorana devices.",
        "positive": "Transport between edge states in multilayer integer quantum Hall\n  systems: exact treatment of Coulomb interactions and disorder: A set of stacked two-dimensional electron systems in a perpendicular magnetic\nfield exhibits a three-dimensional version of the quantum Hall effect if\ninterlayer tunneling is not too strong. When such a sample is in a quantum Hall\nplateau, the edge states of each layer combine to form a chiral metal at the\nsample surface. We study the interplay of interactions and disorder in\ntransport properties of the chiral metal, in the regime of weak interlayer\ntunneling. Our starting point is a system without interlayer tunneling, in\nwhich the only excitations are harmonic collective modes: surface\nmagnetoplasmons. Using bosonization and working perturbatively in the\ninterlayer tunneling amplitude, we express transport properties in terms of the\nspectrum for these collective modes, treating electron-electron interactions\nand impurity scattering exactly. We calculte the conductivity as a function of\ntemperature, finding that it increases with increasing temperature as observed\nin recent experiments. We also calculate the autocorrelation function of\nmesoscopic conductance fluctuations induced by changes in a magnetic field\ncomponent perpendicular to the sample surface, and its dependence on\ntemperature. We show that conductance fluctuations are characterised by a\ndephasing length that varies inversely with temperature."
    },
    {
        "anchor": "Enhancement of crossed Andreev reflection in a Kitaev ladder connected\n  to normal metal leads: We study nonlocal transport in a two-leg Kitaev ladder connected to two\nnormal metals. The coupling between the two legs of the ladder when the legs\nare maintained at a (large) superconducting phase difference, results in the\ncreation of subgap Andreev states. These states in turn are responsible for the\nenhancement of crossed Andreev reflection. We find that tuning the different\nparameters of the system suitably leads to enhancement of crossed Andreev\nreflection signalled by transconductance acquiring the most negative value\npossible. Furthermore, subgap states cause oscillations of the transconductance\nas a function of various system parameters such as chemical potential and\nladder length, which are seen to be a consequence of Fabry-P\\'erot resonance.",
        "positive": "Spin pumping and torque statistics in the quantum noise limit: We analyze the statistics of charge and energy currents and spin torque in a\nmetallic nanomagnet coupled to a large magnetic metal via a tunnel contact. We\nderive a Keldysh action for the tunnel barrier, describing the stochastic\ncurrents in the presence of a magnetization precessing with the rate $\\Omega$.\nIn contrast to some earlier approaches, we include the geometric phases that\naffect the counting statistics. We illustrate the use of the action by deriving\nspintronic fluctuation relations, the quantum limit of pumped current noise,\nand consider the fluctuations in two specific cases: the situation with a\nstable precession of magnetization driven by spin transfer torque, and the\ntorque-induced switching between the minima of a magnetic anisotropy. The\nquantum corrections are relevant when the precession rate exceeds the\ntemperature $T$, i.e., for $\\hbar \\Omega \\gtrsim k_B T$."
    },
    {
        "anchor": "Three-orbital continuous model for $1H$-type metallic transition-metal\n  dichalcogenide monolayers: We theoretically investigate the electronic states in monolayer NbSe$_2$ and\ndevelop continuous models to describe these states in Fermi pockets. In\n$1H$-type metallic transition-metal dichalcogenides(TMDCs), the Femi surface\nconsists of three pockets enclosing the $\\Gamma$, $K$, and $K'$ points. We\nreveal that the conventional effective model used for semiconducting TMDCs is\nnot sufficient to describe the electronic states in metallic TMDCs and thus\nintroduce a scheme to construct the effective model from the first-principles\nresults. All models can be represented by $3\\times3$ Hamiltonian and well\nreproduce electronic states around the Fermi energy in terms of the orbital\ncomposition and the phase factor. We also show that the $p$ orbitals in\nchalcogen atoms, which are ignored in the conventional $2\\times2$ model, play a\ncrucial role in metallic TMDCs. Although the aim of these models is to\nreproduce electronic states, they can well describe states near the\nhigh-symmetry points and the profile of Berry curvature in the wave vector\nspace. The continuous model can be a handleable tool to describe the electronic\nstates and to analyze the transport phenomena in metallic TMDCs.",
        "positive": "Energy levels repulsion by spin-orbit coupling in two-dimensional\n  Rydberg excitons: We study the effects of Rashba spin-orbit coupling on two-dimensional Rydberg\nexciton systems. Using analytical and numerical arguments we demonstrate that\nthis coupling considerably modifies the wave functions and leads to a level\nrepulsion that results in a deviation from the Poissonian statistics of the\nadjacent level distance distribution. This signifies the crossover to\nnon-integrability of the system and hints on the possibility of quantum chaos\nemerging. Such a behavior strongly differs from the classical realization,\nwhere spin-orbit coupling produces highly entangled, chaotic electron\ntrajectories in an exciton. We also calculate the oscillator strengths and show\nthat randomization appears in the transitions between states with different\ntotal momenta."
    },
    {
        "anchor": "Low-energy hole subband dispersions in a cylindrical Ge nanowire: the\n  effects of the nanowire growth direction: We examine the validity of the spherical approximation\n$\\gamma_{s}=(2\\gamma_{2}+3\\gamma_{3})/5$ in the Luttinger-Kohn Hamiltonian in\ncalculating the subband dispersions of the hole gas. We calculate the realistic\nhole subband dispersions (without the spherical approximation) in a cylindrical\nGe nanowire by using quasi-degenerate perturbation theory. The realistic\nlow-energy hole subband dispersions have a double-well anticrossing structure,\nthat consists with the spherical approximation prediction. However, the\nrealistic subband dispersions are also nanowire growth direction dependent.\nWhen the nanowire growth direction is restricted in the (100) crystal plane,\nthe detailed growth direction dependences of the subband parameters are given.\nWe find the spherical approximation is good approximation, it can nicely\nreproduce the real result in some special growth directions.",
        "positive": "In-plane gate single-electron transistor in Ga[Al]As fabricated by\n  scanning probe lithography: A single-electron transistor has been realized in a Ga[Al]As heterostructure\nby oxidizing lines in the GaAs cap layer with an atomic force microscope. The\noxide lines define the boundaries of the quantum dot, the in-plane gate\nelectrodes, and the contacts of the dot to source and drain. Both the number of\nelectrons in the dot as well as its coupling to the leads can be tuned with an\nadditional, homogeneous top gate electrode. Pronounced Coulomb blockade\noscillations are observed as a function of voltages applied to different gates.\nWe find that, for positive top-gate voltages, the lithographic pattern is\ntransferred with high accuracy to the electron gas. Furthermore, the dot shape\ndoes not change significantly when in-plane voltages are tuned."
    },
    {
        "anchor": "Defect-implantation for the all-electrical detection of non-collinear\n  spin-textures: The viability of past, current and future devices for information technology\nhinges on their sensitivity to the presence of impurities. The latter can lead\nto resistivity anomalies, the so-called Kondo effect, reshape extrinsically\nHall effects or reduce the efficiency of magnetoresistance effects essential in\nspintronics. Here we demonstrate that atomic defects enable highly efficient\nall-electrical detection of spin-swirling textures, in particular magnetic\nskyrmions, which are promising bits candidates in future spintronics devices.\nImpurities amplify the bare transport signal and can alter significantly the\nspin-mixing magnetoresistance (XMR) depending on their chemical nature. Both\neffects are monitored in terms of the defect-enhanced XMR (DXMR) as shown for\n3d and 4d transition metal defects implanted at the vicinity of skyrmions\ngenerated in PdFe bilayer deposited on Ir(111). The ineluctability of\nimpurities in devices promotes the implementation of DXMR in reading\narchitectures with immediate implications in magnetic storage technologies.",
        "positive": "Magnetization Reversal Signatures of Hybrid and Pure N\u00e9el Skyrmions in\n  Thin Film Multilayers: We report a study of the magnetization reversals and skyrmion configurations\nin two systems - Pt/Co/MgO and Ir/Fe/Co/Pt multilayers, where magnetic\nskyrmions are stabilized by a combination of dipolar and Dzyaloshinskii-Moriya\ninteractions (DMI). First Order Reversal Curve (FORC) diagrams of low-DMI\nPt/Co/MgO and high-DMI Ir/Fe/Co/Pt exhibit stark differences, which are\nidentified by micromagnetic simulations to be indicative of hybrid and pure\nN\\'eel skyrmions, respectively. Tracking the evolution of FORC features in\nmultilayers with dipolar interactions and DMI, we find that the negative FORC\nvalley, typically accompanying the positive FORC peak near saturation,\ndisappears under both reduced dipolar interactions and enhanced DMI. As these\nconditions favor the formation of pure Neel skyrmions, we propose that the\nresultant FORC feature - a single positive FORC peak near saturation - can act\nas a fingerprint for pure N\\'eel skyrmions in multilayers. Our study thus\nexpands on the utility of FORC analysis as a tool for characterizing spin\ntopology in multilayer thin films."
    },
    {
        "anchor": "Surface roughness noise analysis and comprehensive noise effects on\n  depth-dependent coherence time of NV centers in diamond: Noise is a detrimental issue for nitrogen-vacancy (NV) centers in diamond,\ncausing line broadening and decreasing the coherence time (T2). Following our\nprevious electric and magnetic field noise work, we investigate noise caused by\nthe diamond surface roughness, which is a source for charge density\nfluctuations and incoherent photon scattering. We find that the varying surface\ncharge density noise source is prevalent throughout the entire NV dynamical\ndecoupling frequency range, while the photon scattering noise is almost\nnegligible. Next, we combine the results from various noise sources to perform\ncomprehensive analyses on T2 and how it varies with NV depth. At a given NV\ndepth of 5 nm below a hydrogen- or fluorine-terminated surface, we find that\nthese magnetic nuclei reduce the NV coherence time the most, followed by the\nsurface electric field noise sources. The photon scattering and bulk magnetic\nfield noise effects on T2 are weak compared to the varying charge density,\nelectric dipole, and surface impurity noise. However, with oxygen surface\ntermination, the surface electric field noise becomes comparable to the surface\nmagnetic field noise. Our calculated values of T2,Hahn (few microseconds to ten\nmicroseconds) are in good agreement with the experimental values reported\nelsewhere. Finally, we calculate an anticipated signal-to-noise ratio (SNR) for\nNV AC magnetometry of external nuclear spins. In our simplified assessment,\nwhere some depth-dependent parameters (e.g. NV conversion efficiency) are held\nconstant, we find that shallower NV layers should yield the best SNR, which is\nconsistent with experimental findings.",
        "positive": "Electric control of Dirac quasiparticles by spin-orbit torque in an\n  antiferromagnet: Spin-orbitronics and Dirac quasiparticles are two fields of condensed matter\nphysics initiated independently about a decade ago. Here we predict that Dirac\nquasiparticles can be controlled by the spin-orbit torque reorientation of the\nN\\'{e}el vector in an antiferromagnet. Using CuMnAs as an example, we formulate\nsymmetry criteria allowing for the co-existence of Dirac quasiparticles and\nN\\'{e}el spin-orbit torques. We identify the non-symmorphic crystal symmetry\nprotection of Dirac band crossings whose on and off switching is mediated by\nthe N\\'{e}el vector reorientation. We predict that this concept, verified by\nminimal model and density functional calculations in the CuMnAs semimetal\nantiferromagnet, can lead to a topological metal-insulator transition driven by\nthe N\\'{e}el vector and to the corresponding topological anisotropic\nmagnetoresistance."
    },
    {
        "anchor": "Thermalization of hot electrons via interfacial electron-magnon\n  interaction: Recent work on layered structures of superconductors (S) or normal metals (N)\nin contact with ferromagnetic insulators (FI) has shown how the properties of\nthe previous can be strongly affected by the magnetic proximity effect due to\nthe static FI magnetization. Here we show that such structures can also exhibit\na new electron thermalization mechanism due to the coupling of electrons with\nthe dynamic magnetization, i.e., magnons in FI. We here study the heat flow\nbetween the two systems and find that in thin films the heat conductance due to\nthe interfacial electron-magnon collisions can dominate over the well-known\nelectron-phonon coupling below a certain characteristic temperature that can be\nstraightforwardly reached with present-day experiments. We also study the role\nof the magnon band gap and the induced spin-splitting field induced in S on the\nresulting heat conductance and show that heat balance experiments can reveal\ninformation about such quantities in a way quite different from typical magnon\nspectroscopy experiments.",
        "positive": "Dynamic generation of orbital quasiparticle entanglement in mesoscopic\n  conductors: We propose a scheme for dynamically creating orbitally entangled\nelectron-hole pairs through a time-dependent variation of the electrical\npotential in a mesoscopic conductor. The time-dependent potential generates a\nsuperposition of electron-hole pairs in two different orbital regions of the\nconductor, a Mach-Zehnder interferometer in the quantum Hall regime. The\norbital entanglement is detected via violation of a Bell inequality, formulated\nin terms of zero-frequency current noise. Adiabatic cycling of the potential,\nboth in the weak and strong amplitude limit, is considered."
    },
    {
        "anchor": "Microscopic bath effects on noise spectra in semiconductor quantum dot\n  qubits: When a system is thermally coupled to only a small part of a larger bath,\nstatistical fluctuations of the temperature (more precisely, the internal\nenergy) of this \"sub-bath\" around the mean temperature defined by the larger\nbath can become significant. We show that these temperature fluctuations\ngenerally give rise to 1/f-like noise power spectral density from even a single\ntwo-level system. We extend these results to a distribution of fluctuators,\nfinding the corresponding modification to the Dutta-Horn relation. Then we\nconsider the specific situation of charge noise in silicon quantum dot qubits\nand show that recent experimental data [E. J. Connors, et al., Phys. Rev. B\n100, 165305 (2019)] can be modeled as arising from as few as two two-level\nfluctuators, and accounting for sub-bath size improves the quality of the fit.",
        "positive": "Detection of a single-charge defect in a metal-oxide-semiconductor\n  structure using vertically coupled Al and Si single-electron transistors: An Al-AlO_x-Al single-electron transistor (SET) acting as the gate of a\nnarrow (~ 100 nm) metal-oxide-semiconductor field-effect transistor (MOSFET)\ncan induce a vertically aligned Si SET at the Si/SiO_2 interface near the\nMOSFET channel conductance threshold. By using such a vertically coupled Al and\nSi SET system, we have detected a single-charge defect which is tunnel-coupled\nto the Si SET. By solving a simple electrostatic model, the fractions of each\ncoupling capacitance associated with the defect are extracted. The results\nreveal that the defect is not a large puddle or metal island, but its size is\nrather small, corresponding to a sphere with a radius less than 1 nm. The small\nsize of the defect suggests it is most likely a single-charge trap at the\nSi/SiO_2 interface. Based on the ratios of the coupling capacitances, the\ninterface trap is estimated to be about 20 nm away from the Si SET."
    },
    {
        "anchor": "The orientation of CO intercalated between graphene and Ru(0001): $^{13}$CO molecules are intercalated under a single layer graphene film on\nRu(0001) and interrogated with helium low energy ion scattering. Single\nscattering is used to determine the mass distribution of atomic species visible\nto the ion beam and detector, and the scattering angle is varied to distinguish\nadsorbed from intercalated molecules. At room temperature, CO intercalates as\nmolecules that sit upright with the O end on top, as on clean Ru. The\nintercalated CO tilts, more than it does on clean Ru, when the temperature is\nraised. This is presumably due to increased vibrational amplitudes combined\nwith the confining effect of the graphene film.",
        "positive": "Electrically tunable artificial gauge potential for polaritons: Neutral particles subject to artificial gauge potentials can behave as\ncharged particles in magnetic fields. This fascinating premise has led to\ndemonstrations of one-way waveguides, topologically protected edge states and\nLandau levels for photons. In ultracold neutral atoms effective gauge fields\nhave allowed the emulation of matter under strong magnetic fields leading to\nrealization of Harper-Hofstadter and Haldane models. Here we show that\napplication of perpendicular electric and magnetic fields effects a tuneable\nartificial gauge potential for two-dimensional microcavity exciton polaritons.\nFor verification, we perform interferometric measurement of the associated\nphase accumulated during coherent polariton transport. Since the gauge\npotential originates from the magnetoelectric Stark effect, it can be realized\nfor photons strongly coupled to excitations in any polarizable medium. Together\nwith strong polariton- polariton interactions and engineered polariton\nlattices, artificial gauge fields could play a key role in investigation of\nnon-equilibrium dynamics of strongly correlated photons."
    },
    {
        "anchor": "Exciton absorption, band structure, and optical emission in biased\n  bilayer graphene: Biased bilayer graphene (BBG) is a variable band gap semiconductor, with a\nstrongly field-dependent band gap of up to $300 \\, \\text{meV}$, making it of\nparticular interest for graphene-based nano-electronic and -photonic devices.\nThe optical properties of BBG are dominated by strongly bound excitons. We\nperform ab initio density-functional-theory+Bethe-Salpeter-equation modelling\nof excitons in BBG and calculate the exciton band structures and optical matrix\nelements for field strengths in the range $30-300 \\,\n\\text{mV}/{\\unicode{x212B}}$. The exciton properties prove to have a strong\nfield dependence, with both energy ordering and dipole alignment varying\nsignificantly between the low and high field regions. Namely, at low fields we\nfind a mostly dark ground state exciton, as opposed to high fields, where the\nlowest exciton is bright. Also, excitons preferentially align with a dipole\nmoment opposite the field, due to the field-induced charge transfer in the\nground state of BBG. However, in stronger fields, this alignment becomes\nenergetically less favorable. Additionally, the bright excitons show particle-\nand light-like bands similar to monolayer transition metal dichalchogenides.\nFinally, we model the radiative lifetimes and emission properties of BBG, which\nprove to be strongly dependent on temperature in addition to field strength.",
        "positive": "Temperature dependent resistivity in the doped two dimensional metallic\n  phase of mTMD bilayers: Two recent experiments from Cornell and Columbia have reported\ninsulator-to-metal transitions in two-dimensional (2D) moir\\'e transition metal\ndichalcogenides (mTMD) induced by doping around half-filling, where the system\nis a Mott insulator. In the current work, we consider the temperature dependent\nresistivity of this metallic phase in the doped situation away from\nhalf-filling, arguing that it arises from the strongly temperature dependent 2D\nFriedel oscillations (i.e. finite momentum screening) associated with random\nquenched charged impurities, leading to the observed strongly increasing\nlinear-in-$T$ resistivity in the metallic phase. Our theory appears to account\nfor the temperature-dependent metallic resistivity for doping around\nhalf-filling of the effective moir\\'e TMD band, showing that\ntemperature-dependent screened Coulomb disorder is an essential ingredient of\ndoped 2D mTMD physics."
    },
    {
        "anchor": "P-wave Cooper pair splitting: Splitting of Cooper pairs has recently been realized experimentally for\ns-wave Cooper pairs. A split Cooper pair represents an entangled two-electron\npair state which has possible application in on-chip quantum computation.\nLikewise the spin-activity of interfaces in nanoscale tunnel junctions has been\ninvestigated theoretically and experimentally in recent years. However, the\npossible implications of spin-active interfaces in Cooper pair splitters so far\nhave not been investigated. We analyse the current and the cross correlation of\ncurrents in a superconductor ferromagnet beamsplitter including spin-active\nscattering. Using the Hamiltonian formalism we calculate the cumulant\ngenerating function of charge transfer. As a first step, we discuss\ncharacteristics of the conductance for crossed Andreev reflection in\nsuperconductor ferromagnet beamsplitters with s-wave and p-wave superconductors\nand no spin-active scattering. In a second step, we consider spin-active\nscattering and show how to realize p-wave splitting only using a s-wave\nsuperconductor via the process of spin-flipped crossed Andreev reflection. We\npresent results for the conductance and cross correlations. Spin-activity of\ninterfaces in Cooper pair splitters allows for new features in ordinary s-wave\nCooper pair splitters, that can otherwise only be realised by using p-wave\nsuperconductors. In particular it provides access to Bell states different from\nthe typical spin singlet state.",
        "positive": "Emergence and Dynamical Stability of Charge Time-Crystal in a\n  Current-Carrying Quantum Dot Simulator: Periodically-driven open quantum systems that never thermalize exhibit a\ndiscrete time-crystal behavior, a non-equilibrium quantum phenomenon that has\nshown promise in quantum information processing applications. Measurements of\ntime-crystallinity are currently limited to (magneto-) optical experiments in\natom-cavity systems and spin-systems making it an indirect measurement. We\ntheoretically show that time-crystallinity can be measured directly in the\ncharge-current from a spin-less Hubbard ladder, which can be simulated on a\nquantum-dot array. We demonstrate that one can dynamically tune the system out\nand then back into the time-crystal phase, proving its robustness against\nexternal forcings. These findings motivate further theoretical and experimental\nefforts to simulate the time-crystal phenomena in current-carrying nano-scale\nsystems."
    },
    {
        "anchor": "Linear and nonlinear Stark effect in triangular molecule: We analyze changes of the electronic structure of a triangular molecule under\nthe influence of an electric field (i.e., the Stark effect). The effects of the\nfield are shown to be anisotropic and include both a linear and a nonlinear\npart. For strong electron correlations, we explicitly derive exchange couplings\nin an effective spin Hamiltonian. For some conditions one can find a dark spin\nstate, for which one of the spins is decoupled from the others. The model is\nalso applied for studying electronic transport through a system of three\ncoherently coupled quantum dots. Since electron transfer rates are anisotropic,\nthe current characteristics are anisotropic as well, differing for small and\nlarge electric field.",
        "positive": "Energy-Tunable Quantum Dot with Minimal Fine Structure Created by Using\n  Simultaneous Electric and Magnetic Fields: The neutral biexciton cascade of single quantum dots is a promising source of\nentangled photon pairs. The character of the entangled state is determined by\nthe energy difference between the excitonic eigenstates known as fine-structure\nsplitting (FSS). Here we reduce the magnitude of the FSS by simultaneously\nusing two independent tuning mechanisms: in-plane magnetic field and vertical\nelectric field. We observe that there exists a minimum possible FSS in each\nquantum dot which is independent of these tuning mechanisms. However, with\nsimultaneous application of electric and magnetic fields, we show the FSS can\nbe reduced to its minimum value as the energy of emission is tuned over several\nmeV with a 5-T magnet."
    },
    {
        "anchor": "Third-order polarizability of interlayer excitons in hetero-bilayers: In this paper, we employ a fully microscopic approach to the study of\ninterlayer excitons in hetero-bilayers. We use Fowler's and Karplus' method to\naccess the dynamical polarizability of non--interacting interlayer excitons in\na $\\mathrm{WSe}_{2}/\\mathrm{WS}_{2}$--based van der Waals heterostructure.\nFollowing from the calculation of the linear polarizability, we consider\nSvendsen's variational method to the calculation of the dynamic third--order\npolarizability. With this variational method, we study both two--photon\nabsorption and third--harmonic generation processes for interlayer excitons in\na $\\mathrm{WSe}_{2}/\\mathrm{WS}_{2}$ hetero--bilayer, discussing the various\nselection rules of intra--excitonic energy level transitions.",
        "positive": "Decoherence induced by anisotropic hyperfine interaction in Si spin\n  qubits: We study Si:P donor electron spin decoherence due to anisotropic hyperfine\n(AHF) interaction with the surrounding nuclear spin bath. In particular, we\nclarify the electron spin echo envelope modulation (ESEEM) in the Si:P system\nand the resonancelike contributions from nuclear spins in various shells away\nfrom the P atoms. We suggest an approach to minimize AHF-induced decoherence by\navoiding the resonances and orienting an applied magnetic field along\ndirections that can periodically eliminate contributions from the dominant\nnearest neighbor atoms. Our remarkable agreement with experiment demonstrates\nnearly complete understanding of electron spin decoherence in Si:P when\ncombining ESEEM, spectral diffusion, instantaneous diffusion, and spin-lattice\nrelaxation."
    },
    {
        "anchor": "Quantum metrology with a single spin-$3/2$ defect in silicon carbide: We show that implementations for quantum sensing with exceptional sensitivity\nand spatial resolution can be made using spin-3/2 semiconductor defect states.\nWe illustrate this using the silicon monovacancy deep center in hexagonal SiC\nbased on our rigorous derivation of this defect's ground state and of its\nelectronic and optical properties. For a single $\\textrm{V}_{\\textrm{Si}}^-$\ndefect, we obtain magnetic field sensitivities capable of detecting individual\nnuclear magnetic moments. We also show that its zero-field splitting has an\nexceptional strain and temperature sensitivity within the technologically\ndesirable near-infrared window of biological systems. The concepts and sensing\nschemes developed here are applicable to other point defects with half spin\nmultiplet ($S\\geq 3/2$) configuration.",
        "positive": "Dimensional evolution between one- and two-dimensional topological\n  phases: Dimensional evolution between one- ($1D$) and two-dimensional ($2D$)\ntopological phases is investigated systematically. The crossover from a $2D$\ntopological insulator to its $1D$ limit shows oscillating behavior between a\n$1D$ ordinary insulator and a $1D$ topological insulator. By constructing a\n$2D$ topological system from a $1D$ topological insulator, it is shown that\nthere exist possibly weak topological phases in $2D$ time-reversal invariant\nband insulators, one of which can be realized in anisotropic systems. The\ntopological invariant of the phase is $Z_{2}=0$. However the edge states may\nappear along specific boundaries. It can be interpreted as arranged $1D$\ntopological phases, and have symmetry-protecting nature as the corresponding\n$1D$ topological phase. Robust edge states can exist under specific conditions.\nThese results provide further understanding on $2D$ time-reversal invariant\ninsulators, and can be realized experimentally."
    },
    {
        "anchor": "Development of high frequency and wide bandwidth Johnson noise\n  thermometry: We develop a high frequency, wide bandwidth radiometer operating at room\ntemperature, which augments the traditional technique of Johnson noise\nthermometry for nanoscale thermal transport studies. Employing low noise\namplifiers and an analog multiplier operating at 2~GHz, auto- and\ncross-correlated Johnson noise measurements are performed in the temperature\nrange of 3 to 300~K, achieving a sensitivity of 5.5~mK (110 ppm) in 1 second of\nintegration time. This setup allows us to measure the thermal conductance of a\nboron nitride encapsulated monolayer graphene device over a wide temperature\nrange. Our data shows a high power law (T$^{\\sim4}$) deviation from the\nWiedemann-Franz law above T$\\sim$100~K.",
        "positive": "Fermionic Chern insulator from twisted light with linear polarization: The breaking of time-reversal symmetry is a crucial ingredient to topological\nbands. It can occur intrisically in materials with magnetic order, or be\ninduced by external fields, such as magnetic fields in quantum Hall systems, or\ncircularly polarized light fields in Floquet Chern insulators. Apart from\npolarization, photons can carry another degree of freedom, orbital angular\nmomentum, through which time-reversal symmetry can be broken. In this Letter,\nwe pose the question whether this property allows for inducing topological\nbands via a linearly polarized but twisted light beam. To this end, we study a\ngraphene-like model of electrons on a honeycomb lattice interacting with a\ntwisted light field. To identify topological behavior of the electrons, we\ncalculate their local markers of Chern number, and monitor the presence of\nin-gap edge states. Our results are shown to be fully analogous to the behavior\nfound in paradigmatic models for static and driven Chern insulators, and\nrealizing the state is experimentally straightforward. With this, our work\nestablishes a new mechanism for generating Fermionic topological phases of\nmatter that can harness the central phase singularity of an optical vortex\nbeam."
    },
    {
        "anchor": "Transition of a 2D spin mode to a helical state by lateral confinement: Spin-orbit interaction (SOI) leads to spin precession about a\nmomentum-dependent spin-orbit field. In a diffusive two-dimensional (2D)\nelectron gas, the spin orientation at a given spatial position depends on which\ntrajectory the electron travels to that position. In the transition to a 1D\nsystem with increasing lateral confinement, the spin orientation becomes more\nand more independent on the trajectory. It is predicted that a long-lived\nhelical spin mode emerges. Here we visualize this transition experimentally in\na GaAs quantum-well structure with isotropic SOI. Spatially resolved\nmeasurements show the formation of a helical mode already for non-quantized and\nnon-ballistic channels. We find a spin-lifetime enhancement that is in\nexcellent agreement with theoretical predictions. Lateral confinement of a 2D\nelectron gas provides an easy-to-implement technique for achieving high spin\nlifetimes in the presence of strong SOI for a wide range of material systems.",
        "positive": "Construction of optimized tight-binding models using \\textit{ab initio}\n  Hamiltonian: Application to monolayer $2H$-transition metal dichalcogenides: We present optimized tight-binding models with atomic orbitals to improve\n\\textit{ab initio} tight-binding models constructed by truncating full density\nfunctional theory (DFT) Hamiltonian based on localized orbitals. Retaining\nqualitative features of the original Hamiltonian, the optimization reduces\nquantitative deviations in overall band structures between the \\textit{ab\ninitio} tight-binding model and the full DFT Hamiltonian. The optimization\nprocedure and related details are demonstrated by using semiconducting and\nmetallic Janus transition metal dichalcogenides monolayers in the $2H$\nconfiguration. Varying the truncation range from partial second neighbors to\nthird ones, we show differences in electronic structures between the truncated\ntight-binding model and the original full Hamiltonian, and how much the\noptimization can remedy the quantitative loss induced by truncation. We further\nelaborate the optimization process so that local electronic properties such as\nvalence and conduction band edges and Fermi surfaces are precisely reproduced\nby the optimized tight-binding model. We also extend our discussions to\ntight-binding models including spin-orbit interactions, so we provide the\noptimized tight-binding model replicating spin-related properties of the\noriginal Hamiltonian such as spin textures. The optimization process described\nhere can be readily applied to construct the fine-tuned tight-binding model\nbased on various DFT calculations."
    },
    {
        "anchor": "Dynamical screening function and plasmons in the wide HgTe quantum wells\n  at high temperatures: Dynamical screening function of the two-dimensional electron gas in wide HgTe\nquantum well (QW) has been numerically modelled in this work. Calculations were\nprovided in the Random Phase Approximation (RPA) framework and were based on\nLindhard equation. Our simulations directly incorporated non-parabolicity of\nbulk 2D carriers spectrum, which was obtained by full 8-band k.p method. In the\nliterature exists data that transport properties of HgTe QWs are explained by\ngraphene-like screening. We provide the comparison of the screening function\nfor the Schrodinger fermions in the inverted bands HgTe QW with the appropriate\nscreening function for graphene monolayer with the Dirac fermions. In addition,\nthe dependencies of HgTe-specific screening function on temperature, scattering\nwave-vector and frequency are studied with the purpose to study the transport\nproperties under high-frequency radiation the QWs structures to be used as THz\ndetectors. Plasmon frequencies of 2DEG in HgTe quantum well under study were\ncalculated in the long-wavelength limit for T=77K.",
        "positive": "Quantum Surface-Response of Metals Revealed by Acoustic Graphene\n  Plasmons: A quantitative understanding of the electromagnetic response of materials is\nessential for the precise engineering of maximal, versatile, and controllable\nlight--matter interactions. Material surfaces, in particular, are prominent\nplatforms for enhancing electromagnetic interactions and for tailoring chemical\nprocesses. However, at the deep nanoscale, the electromagnetic response of\nelectron systems is significantly impacted by quantum surface-response at\nmaterial interfaces, which is challenging to probe using standard optical\ntechniques. Here, we show how ultra-confined acoustic graphene plasmons (AGPs)\nin graphene--dielectric--metal structures can be used to probe the quantum\nsurface-response functions of nearby metals, here encoded through the so-called\nFeibelman $d$-parameters. Based on our theoretical formalism, we introduce a\nconcrete proposal for experimentally inferring the low-frequency quantum\nresponse of metals from quantum shifts of the AGPs' dispersion, and demonstrate\nthat the high field confinement of AGPs can resolve intrinsically quantum\nmechanical electronic length-scales with subnanometer resolution. Our findings\nreveal a promising scheme to probe the quantum response of metals, and further\nsuggest the utilization of AGPs as plasmon rulers with \\r{a}ngstr\\\"{o}m-scale\naccuracy."
    },
    {
        "anchor": "Progress in Analytical Solutions for High Order Harmonic Generation in\n  Semiconductor Superlattice Multipliers: In this study, we address the limitations of previous solutions for modeling\nhigh-order harmonics in semiconductor superlattices (SSLs). Earlier research\nproposed a step function ansatz that effectively modeled high-order even and\nodd harmonics but introduced numerical noise. An upgrade using a logistic\nfunction addressed the noise problem but eliminated high-order odd harmonics.\nTo overcome both limitations, we examined the impact of the y-intercept value\nin the discontinuity of the step function and proposed a modified logistic\nfunction as a new ansatz. The modified logistic function delivers accurate\nresults, preserving high-order odd harmonics up to the 50th order similar to\nthe previous ansatz while also eliminating numerical noise. This research\ncontributes to a more efficient and robust analytical approach for modeling\nSSLs, notably by avoiding time-consuming numerical solutions and enhancing our\nunderstanding of nonlinear phenomena in GHz-THz devices.",
        "positive": "Optical properties of van der Waals heterostructure of uniaxially\n  strained graphene on TMD: The spin and valley polarizations and plasmonics in Van der Waals\nheterostructures of strained graphene monolayer on 2D transition metal\ndichalcogenide (GrTMD) substrate are reported in this communication. The\nsubstrate induced interactions (SII) involve sub-lattice-resolved, and enhanced\nintrinsic spin-orbit couplings, the extrinsic Rashba spin-orbit coupling\n(RSOC), and the orbital gap related to the transfer of the electronic charge\nfrom graphene to the substrate. Furthermore, magnetic impurity atoms are\ndeposited to the graphene surface and the corresponding exchange field is\nincluded in the band dispersion. A Rashba coupling dependent pseudo Zeeman term\narising due to the interplay of SIIs was found to be responsible for the spin\ndegeneracy lifting and the spin polarization. The latter turns out to be\nelectrostatic doping and the exchange field tunable and inversely proportional\nto the square root of the carrier concentration. The strain field, on the other\nhand, brings about the valley polarization. The intra-band plasmon dispersion\nfor the finite doping and the long wavelength limit has also been obtained. The\ndispersion involves the q2/3 behavior and not the well known q1/2 behavior. The\nuniform, uniaxial strain does not bring about any change in this behavior.\nHowever, the plasmon dispersion gets steeper for the wavevector perpendicular\nto the direction of strain and is flattened for wave vectors along the\ndirection of the strain with the term responsible for the flattening\nproportional to the strain field. The stronger confinement capability of GrTMD\nPlasmon compared to that of standalone, doped graphene is an important outcome\nof the present work. One finds that whereas the intra-band absorbance of GrTMD\nis decreasing function of the frequency at a given strain field, it is an\nincreasing function of the strain field at a given frequency."
    },
    {
        "anchor": "Hybrid continuous dynamical decoupling: a photon-phonon doubly dressed\n  spin: We study the parametric interaction between a single Nitrogen-Vacancy\nelectronic spin and a diamond mechanical resonator in which the spin is\nembedded. Coupling between spin and oscillator is achieved by crystal strain,\nwhich is generated upon actuation of the oscillator and which parametrically\nmodulates the spins' energy splitting. Under coherent microwave driving of the\nspin, this parametric drive leads to a locking of the spin Rabi frequency to\nthe oscillator mode in the megahertz range. Both the Rabi oscillation decay\ntime and the inhomogeneous spin dephasing time increase by two orders of\nmagnitude under this spin-locking condition. We present routes to prolong the\ndephasing times even further, potentially to the relaxation time limit. The\nremarkable coherence protection that our hybrid spin-oscillator system offers\nis reminiscent of recently proposed concatenated continuous dynamical\ndecoupling schemes and results from our robust, drift-free strain-coupling\nmechanism and the narrow linewidth of the high-quality diamond mechanical\noscillator employed. Our findings suggest feasible applications in quantum\ninformation processing and sensing.",
        "positive": "Device Model for Graphene Bilayer Field-Effect Transistor: We present an analytical device model for a graphene bilayer field-effect\ntransistor (GBL-FET) with a graphene bilayer as a channel, and with back and\ntop gates. The model accounts for the dependences of the electron and hole\nFermi energies as well as energy gap in different sections of the channel on\nthe bias back-gate and top-gate voltages. Using this model, we calculate the dc\nand ac source-drain currents and the transconductance of GBL-FETs with both\nballistic and collision dominated electron transport as functions of structural\nparameters, the bias back-gate and top-gate voltages, and the signal frequency.\nIt is shown that there are two threshold voltages, $V_{th,1}$ and $V_{th,2}$,\nso that the dc current versus the top-gate voltage relation markedly changes\ndepending on whether the section of the channel beneath the top gate (gated\nsection) is filled with electrons, depleted, or filled with holes. The electron\nscattering leads to a decrease in the dc and ac currents and transconductances,\nwhereas it weakly affects the threshold frequency. As demonstrated, the\ntransient recharging of the gated section by holes can pronouncedly influence\nthe ac transconductance resulting in its nonmonotonic frequency dependence with\na maximum at fairly high frequencies."
    },
    {
        "anchor": "Destructive Little-Parks Effect in a Full-Shell Nanowire-based Transmon: A semiconductor transmon with an epitaxial Al shell fully surrounding an InAs\nnanowire core is investigated in the low $E_J/E_C$ regime. Little-Parks\noscillations as a function of flux along the hybrid wire axis are destructive,\ncreating lobes of reentrant superconductivity separated by a metallic state at\na half-quantum of applied flux. In the first lobe, phase winding around the\nshell can induce topological superconductivity in the core. Coherent qubit\noperation is observed in both the zeroth and first lobes. Splitting of parity\nbands by coherent single-electron coupling across the junction is not resolved\nbeyond line broadening, placing a bound on Majorana coupling, $E_M/h$ < 10 MHz,\nmuch smaller than the Josephson coupling $E_J/h$ ~ 4.7 GHz.",
        "positive": "Interface Landau levels in graphene monolayer-bilayer junction: Electronic structure of graphene monolayer-bilayer junction in a magnetic\nfield is studied within an effective-mass approximation. The energy spectrum is\ncharacterized by interface Landau levels, i.e., the locally flat bands\nappearing near the boundary region, resulting in a series of characteristic\npeaks in the local density of states. Their energies are independent of\nboundary types such as zigzag or armchair. In the atomic scale, the local\ndensity of states shows a Kekul\\'{e} pattern due to the valley mixing in the\narmchair boundary, while does not in the zigzag boundary."
    },
    {
        "anchor": "Anisotropic scattering and quantum magnetoresistivities of a\n  periodically modulated 2D electron gas: We calculate the longitudinal conductivities of a two-dimensional\nnoninteracting electron gas in a uniform magnetic field and a lateral electric\nor magnetic periodic modulation in one spatial direction, in the quantum\nregime. We consider the effects of the electron-impurity scattering anisotropy\nthrough the vertex corrections on the Kubo formula, which are calculated with\nthe Bethe-Salpeter equation, in the self-consistent Born approximation. We find\nthat due to the scattering anisotropy the band conductivity increases, and the\nscattering conductivities decrease and become anisotropic. Our results are in\nqualitative agreement with recent experiments.",
        "positive": "Spin current through a tunnel junction: We derive an expression for the spin-current through a tunnel barrier in\nterms of many-body Green's functions. The spin current has two contributions.\nOne can be associated with angular-momentum transfer by spin-polarized charge\ncurrents crossing the junction. If there are magnetic moments on both sides of\nthe tunnel junction, due to spin accumulation or ferromagnetic ordering, then\nthere is a second contribution related to the exchange coupling between the\nmoments."
    },
    {
        "anchor": "Anisotropy of graphite optical conductivity: The graphite conductivity is evaluated for frequencies between\n  0.1 eV, the energy of the order of the electron-hole overlap, and 1.5 eV, the\nelectron nearest hopping energy. The in-plane conductivity per single atomic\nsheet is close to the universal graphene conductivity $e^2/4\\hbar$ and,\nhowever, contains a singularity conditioned by peculiarities of the electron\ndispersion. The conductivity is less in the $c-$direction by the factor of the\norder of 0.01 governed by electron hopping in this direction.",
        "positive": "Electrical spectroscopy of forward volume spin waves in perpendicularly\n  magnetized materials: We study the potential of all-electrical inductive techniques for the\nspectroscopy of propagating forward volume spin waves. We develop a\none-dimensional model to account for the electrical signature of spin-wave\nreflection and transmission between inductive antennas and validate it with\nexperiments on a perpendicularly magnetized Co/Ni multilayer. We describe the\ninfluence of the antenna geometry and antenna-to-antenna separation, as well as\nthat of the material parameters on the lineshape of the inductive signals. For\na finite damping, the broadband character of the antenna emission in the wave\nvector space imposes to take into account the growing decoherence of the\nmagnetization waves upon their spatial propagation. The transmission signal can\nbe viewed as resulting from two contributions: a first one from propagating\nspin-waves leading to an oscillatory phase of the broadband transmission\ncoefficient, and another one originating from the distant induction of\nferromagnetic resonance because of the long-range stray fields of realistic\nantennas. Depending on the relative importance of these two contributions, the\ndecay of the transmitted signal with the propagation distance may not be\nexponential and the oscillatory character of the spin-wave phase upon\npropagation may be hidden. Our model and its experimental validation allow to\ndefine geometrical and material specifications to be met to enable the use of\nforward volume spin waves as efficient information carriers."
    },
    {
        "anchor": "The antibunching effect of polaritons in a microcavity dimer: We are consistency considered two cases. Firstly, we consider exciton-photon\nstatistic radiation from pillar microcavity. We obtained a photon antibunching\nand small polariton antibunching. Secondly, we use two strong-coupled pillar\nmicrocavities to achieve pronounced polariton antibunching. We observed the\npolariton blockade effect when use a polarion dimer.",
        "positive": "Quantum Phase Transitions in Quantum Dots: This review article describes theoretical and experimental advances in using\nquantum dots as a system for studying impurity quantum phase transitions and\nthe non-Fermi liquid behavior at the quantum critical point."
    },
    {
        "anchor": "Quantized magnetic confinement in quantum wires: Ballistic quantum wires are exposed to longitudinal profiles of perpendicular\nmagnetic fields composed of a spike (magnetic barrier) and a homogeneous part.\nAn asymmetric magnetoconductance peak as a function of the homogeneous magnetic\nfield is found, comprising quantized conductance steps in the interval where\nthe homogeneous magnetic field and the magnetic barrier have identical\npolarities, and a characteristic shoulder with several resonances in the\ninterval of opposite polarities. The observations are interpreted in terms of\ninhomogeneous diamagnetic shifts of the quantum wire modes leading to magnetic\nconfinement.",
        "positive": "Quantum dot dephasing by edge states: We calculate the dephasing rate of an electron state in a pinched quantum\ndot, due to Coulomb interactions between the electron in the dot and electrons\nin a nearby voltage biased ballistic nanostructure. The dephasing is caused by\nnonequilibrium time fluctuations of the electron density in the nanostructure,\nwhich create random electric fields in the dot. As a result, the electron level\nin the dot fluctuates in time, and the coherent part of the resonant\ntransmission through the dot is suppressed."
    },
    {
        "anchor": "Revealing the Exciton Fine Structure in PbSe Nanocrystal Quantum Dots: We measure the photoluminescence (PL) lifetime, $\\tau$, of excitons in\ncolloidal PbSe nanocrystals (NCs) at low temperatures to 270~mK and in high\nmagnetic fields to 15~T. For all NCs (1.3-2.3~nm radii), $\\tau$ increases\nsharply below 10~K but saturates by 500~mK. In contrast to the usual picture of\nwell-separated ``bright\" and ``dark\" exciton states (found, e.g., in CdSe NCs),\nthese dynamics fit remarkably well to a system having two exciton states with\ncomparable - but small - oscillator strengths that are separated by only\n300-900 $\\mu$eV. Importantly, magnetic fields reduce $\\tau$ below 10~K,\nconsistent with field-induced mixing between the two states. Magnetic circular\ndichroism studies reveal exciton g-factors from 2-5, and magneto-PL shows\n$>$10\\% circularly polarized emission.",
        "positive": "Thickness-dependent Dielectric Constant of Few-layer In2Se3 Nano-flakes: The dielectric constant or relative permittivity of a dielectric material,\nwhich describes how the net electric field in the medium is reduced with\nrespect to the external field, is a parameter of critical importance for\ncharging and screening in electronic devices. Such a fundamental material\nproperty is intimately related to not only the polarizability of individual\natoms, but also the specific atomic arrangement in the crystal lattice. In this\nletter, we present both experimental and theoretical investigations on the\ndielectric constant of few-layer In2Se3 nano-flakes grown on mica substrates by\nvan der Waals epitaxy. A nondestructive microwave impedance microscope is\nemployed to simultaneously quantify the number of layers and local electrical\nproperties. The measured dielectric constant increases monotonically as a\nfunction of the thickness and saturates to the bulk value at around 6 ~ 8\nquintuple layers. The same trend of layer-dependent dielectric constant is also\nrevealed by first-principle calculations. Our results of the dielectric\nresponse, being ubiquitously applicable to layered 2D semiconductors, are\nexpected to be significant for this vibrant research field."
    },
    {
        "anchor": "Current-induced instability of domain walls in cylindrical nanowires: We study the current-driven domain wall (DW) motion in cylindrical nanowires\nusing micromagnetic simulations by implementing the Landau-Lifshitz-Gilbert\nequation with nonlocal spin-transfer torque in a finite difference\nmicromagnetic package. We find that in the presence of DW Gaussian wave packets\n(spin waves) will be generated when the charge current is applied to the system\nsuddenly. And this effect is excluded when using the local spin-transfer\ntorque. The existence of spin waves emission indicates that transverse domain\nwalls can not move arbitrarily fast in cylindrical nanowires although they are\nfree from the Walker limit. We establish an upper-velocity limit for the DW\nmotion by analyzing the stability of Gaussian wave packets using the local\nspin-transfer torque. Micromagnetic simulations show that the stable region\nobtained by using nonlocal spin-transfer torque is smaller than that by using\nits local counterpart. This limitation is essential for multiple domain walls\nsince the instability of Gaussian wave packets will break the structure of\nmultiple domain walls.",
        "positive": "Energy Gaps and Plateau Characteristics in the Fractional Quantum Hall\n  Effect Derive from Multi-particle Correlations: The energy gaps appearing in the fractional quantum Hall effect (FQHE) remain\nan essential aspect of the investigation. Moreover, the plateau widths in the\nHall resistance have been considered simply an effect of disorder as in the\nintegral quantum Hall effect. The existing theories could neither explain the\nHall resistance curve owing to plateau widths nor calculate the energy gaps.\nThis study reveals that both the energy gaps and plateau widths contain\nfundamental many-body aspects of the FQHE. They are found to be connected via\nthe strengths of multi-particle correlations, which do not affect the plateau\nheights. They are automatically quantized just by the presence of\nmulti-particle correlations. This work focuses on correlated skipping electrons\nmoving through the edge of an incompressible strip formed within a Hall bar.\nConsequently, a single-particle Hamiltonian was constructed incorporating the\nZeeman energies of multiply-correlated skipping electrons. The resulting energy\nspectrum exhibits hierarchical splits of the Landau levels according to\ncorrelation order. The lowest Landau level is examined. Based on such level\nsplitting, a previously measured Hall resistance curve and energy gaps are\nquantitatively explained by determining the parameters that describe the\ndegrees of multi-particle correlations. The chemical potential and effective\n$g$-factors are additionally predicted for the Hall resistance. Furthermore,\nthe fractional electron charge $e/(2n+1)$ for an electron participating in\n$n$-particle correlation was obtained by identifying the Fermi distribution\nfunction of $n$ correlated basic transport entities moving through the edge of\nthe incompressible strip. Finally, the ideal-like Hall resistance was obtained\nat half-filling using the strengths of multi-particle correlations given in a\nregular pattern."
    },
    {
        "anchor": "Anomalous Electrodynamics and Quantum Geometry in the Dirac-Harper model\n  for a Graphene Bilayer: Graphene bilayers with layer antisymmetric strains are studied using the\nDirac-Harper model for a pair of single layer Dirac Hamiltonians coupled by a\none-dimensional moir\\'e-periodic interlayer tunneling amplitude. This model\nhosts low energy, nearly dispersionless bands near charge neutrality that\nsupport anomalous polarizations of its charge multipole distributions. These\nare analyzed introducing a generalized Berry curvature that encodes the\nfield-induced dynamics of multipole fields allowed in a chiral medium with time\nreversal symmetry. The formulation identifies a reciprocity relation between\nresponses to layer-symmetric and layer-antisymmetric in-plane electric fields\nand reveals momentum-space quantum oscillations produced by a spatial pattern\nof band inversions on the moir\\'e scale.",
        "positive": "Anomalous Raman features of silicon nanowires under high pressure: The potential of silicon nanowires (SiNWs), (diameter < 10 nm) to transform\ninto rigid bundle-like structures with distinct phonon confinement under high\npressure (<= 15 GPa), instead of amorphising as per previous reports, is\ndemonstrated using in-situ Raman spectroscopy. The newly observed splitting of\nthe second order transverse optical (2TO) Raman mode into 2TO(L) and 2TO(W)\nphonon modes at >= 5 GPa establishes a highly anisotropic and mode-dependent\npressure response of these SiNWs. Properties of the novel structures are\nsuperior compared to other nano-structured silicon and bulk-Si in terms of\nincreased linear modulus, more localized phonon confinement and less\nanharmonicity."
    },
    {
        "anchor": "Penetration of Arbitrary Double Potential Barriers with Probability\n  Unity: Implications for Testing the Existence of a Minimum Length: Quantum tunneling across double potential barriers is studied. With the\nassumption that the real space is a continuum, it is rigorously proved that\nlarge barriers of arbitrary shapes can be penetrated by low-energy particles\nwith a probability of unity, i.e., realization of resonant tunneling (RT), by\nsimply tuning the inter-barrier spacing. The results are demonstrated by\ntunneling of electrons and protons, in which resonant and sequential tunneling\nare distinguished. The critical dependence of tunneling probabilities on the\nbarrier positions not only demonstrates the crucial role of phase factors, but\nalso points to the possibility of ultrahigh accuracy measurements near\nresonance. By contrast, the existence of a nonzero minimum length puts upper\nbounds on the barrier size and particle mass, beyond which effective RT ceases.\nA scheme is suggested for dealing with the practical difficulties arising from\nthe delocalization of particle position due to the uncertainty principle. This\nwork opens a possible avenue for experimental tests of the existence of a\nminimum length based on atomic systems.",
        "positive": "Uniaxial strain on gapped graphene: We study the effect of uniaxial strain on the electronic band structure of\ngapped graphene. We consider two types of gapped graphene, one which breaks the\nsymmetry between the two triangular sublattices (staggered model), and another\nwhich alternates the bonds on the honeycomb lattice (Kekul\\'e model). In the\nstaggered model, the effect of strains below a critical value is only a shift\nof the band gap location. In the Kekul\\'e model, as strain is increased, band\ngap location is initially pinned to a corner of the Brillouin zone while its\nwidth diminishes, and after gap closure the location of the contact point\nbegins to shift. Analytic and numerical results are obtained for both the\ntight-binding and Dirac fermion descriptions of gapped graphene."
    },
    {
        "anchor": "Single photon emission from graphene quantum dots at room temperature: In the field of condensed matter, graphene plays a central role as an\nemerging material for nanoelectronics. Nevertheless, graphene is a semimetal,\nwhich constitutes a severe limitation for some future applications. Therefore,\na lot of efforts are being made to develop semiconductor materials whose\nstructure is compatible with the graphene lattice. In this perspective, little\npieces of graphene represent a promising alternative. In particular, their\nelectronic, optical and spin properties can be in principle controlled by\ndesigning their size, shape and edges. As an example, graphene nanoribbons with\nzigzag edges have localized spin polarized states. Likewise, singlet-triplet\nenergy splitting can be chosen by designing the structure of graphene quantum\ndots. Moreover, bottom-up molecular synthesis put these potentialities at our\nfingertips. Here, we report on a single emitter study that directly addresses\nthe intrinsic properties of a single graphene quantum dot. In particular, we\nshow that graphene quantum dots emit single photons at room temperature with a\nhigh purity, a high brightness and a good photostability. These results pave\nthe way to the development of new quantum systems based on these nanoscale\npieces of graphene.",
        "positive": "Inter-dot coupling and excitation transfer mechanisms of\n  telecommunication band InAs quantum dots at elevated temperatures: We investigate the photoluminescence temperature dependence of individual\nInAs/InGaAlAs quantum dots emitting in the optical telecommunication bands. The\nhigh-density dots are grown on InP substrates and the selection of a smaller\ndot number is done by the processing of suitable nanometer sized mesas. Using\nensembles of only a few dots inside such mesas, their temperature stability,\ninter-dot charge transfer, as well as, carrier capture and escape mechanisms\nout of the dots are investigated systematically. This includes the discussion\nof the dot ensemble and individual dots. Among the single-dot properties, we\ninvestigate the transition of emission lines from zero-phonon line to acoustic\nphonon sideband dominated line shape with temperature. Moreover, the presence\nof single recombination lines up to temperatures of around 150 K is\ndemonstrated."
    },
    {
        "anchor": "A computational approach to quantum noise in time-dependent\n  nanoelectronic devices: We derive simple expressions that relate the noise and correlation properties\nof a general time-dependent quantum conductor to the wave functions of the\nsystem. The formalism provides a practical route for numerical calculations of\nquantum noise in an externally driven system. We illustrate the approach with\nnumerical calculations of the noise properties associated to a voltage pulse\napplied on a one-dimensional conductor. The methodology is however fully\ngeneral and can be used for a large class of mesoscopic conductors.",
        "positive": "Detecting Bulk Topology of Quadrupolar Phase from Quench Dynamics: Direct measurement of a bulk topological observable in topological phase of\nmatter has been a long-standing issue. Recently, detection of bulk topology\nthrough quench dynamics has attracted growing interests. Here, we propose that\ntopological characters of a quantum quadrupole insulator can be read out by\nquench dynamics. Specifically, we introduce a quantity, a quadrupole moment\nweighted by the eigenvalues of the chiral operator, which takes zero for the\ntrivial phase and finite for the quadrupolar topological phase. By utilizing an\nefficient numerical method to track the unitary time evolution, we elucidate\nthat the quantity we propose indeed serves as an indicator of topological\ncharacter for both noninteracting and interacting cases. The robustness against\ndisorders is also demonstrated."
    },
    {
        "anchor": "Surface Atom Motion to Move Iron Nanocrystals through Constrictions in\n  Carbon Nanotubes under the Action of an Electric Current: Under the application of electrical currents, metal nanocrystals inside\ncarbon nanotubes can be bodily transported. We examine experimentally and\ntheoretically how an iron nanocrystal can pass through a constriction in the\ncarbon nanotube with a smaller cross-sectional area than the nanocrystal\nitself. Remarkably, through in situ transmission electron imaging and\ndiffraction, we find that, while passing through a constriction, the\nnanocrystal remains largely solid and crystalline and the carbon nanotube is\nunaffected. We account for this behavior by a pattern of iron atom motion and\nrearrangement on the surface of the nanocrystal. The nanocrystal motion can be\ndescribed with a model whose parameters are nearly independent of the\nnanocrystal length, area, temperature, and electromigration force magnitude. We\npredict that metal nanocrystals can move through complex geometries and\nconstrictions, with implications for both nanomechanics and tunable synthesis\nof metal nanoparticles.",
        "positive": "Dephasing of Andreev pairs entering a charge density wave: An Andreev pair from a s-wave superconductor (S) entering a conventional\ngapless charge density wave (CDW) below the Peierls gap dephases on the Fermi\nwavelength while one particle states are localized on the CDW coherence length.\nThe paths following different sequences of impurities interfere destructively,\ndue to the different electron and hole densities in the CDW. The same\nconclusion holds for averaging over the conduction channels in the ballistic\nsystem. We apply two microscopic approaches to this phenomenon: i) a Blonder,\nTinkham, Klapwijk (BTK) approach for a single highly transparent S-CDW\ninterface; and ii) the Hamiltonian approach for the Josephson effect in a clean\nCDW and a CDW with non magnetic disorder. The Josephson effect through a spin\ndensity wave (SDW) is limited by the coherence length, not by the Fermi\nwave-length."
    },
    {
        "anchor": "Zero-point spin-fluctuations of single adatoms: Stabilizing the magnetic signal of single adatoms is a crucial step towards\ntheir successful usage in widespread technological applications such as\nhigh-density magnetic data storage devices. The quantum mechanical nature of\nthese tiny objects, however, introduces intrinsic zero-point spin-fluctuations\nthat tend to destabilize the local magnetic moment of interest by dwindling the\nmagnetic anisotropy potential barrier even at absolute zero temperature. Here,\nwe elucidate the origins and quantify the effect of the fundamental ingredients\ndetermining the magnitude of the fluctuations, namely the ($i$) local magnetic\nmoment, ($ii$) spin-orbit coupling and ($iii$) electron-hole Stoner\nexcitations. Based on a systematic first-principles study of 3d and 4d adatoms,\nwe demonstrate that the transverse contribution of the fluctuations is\ncomparable in size to the magnetic moment itself, leading to a remarkable\n$\\gtrsim$50$\\%$ reduction of the magnetic anisotropy energy. Our analysis gives\nrise to a comprehensible diagram relating the fluctuation magnitude to\ncharacteristic features of adatoms, providing practical guidelines for\ndesigning magnetically stable nanomagnets with minimal quantum fluctuations.",
        "positive": "Scattering of charge and spin excitations and equilibration of a\n  one-dimensional Wigner crystal: We study scattering of charge and spin excitations in a system of interacting\nelectrons in one dimension. At low densities electrons form a one-dimensional\nWigner crystal. To first approximation the charge excitations are the phonons\nin the Wigner crystal, and the spin excitations are described by the Heisenberg\nmodel with nearest neighbor exchange coupling. This model is integrable and\nthus incapable of describing some important phenomena, such as scattering of\nexcitations off each other and the resulting equilibration of the system. We\nobtain the leading corrections to this model, including charge-spin coupling\nand the next-nearest neighbor exchange in the spin subsystem. We apply the\nresults to the problem of equilibration of the one-dimensional Wigner crystal\nand find that the leading contribution to the equilibration rate arises from\nscattering of spin excitations off each other. We discuss the implications of\nour results for the conductance of quantum wires at low electron densities."
    },
    {
        "anchor": "Two-dimensional weak topological insulators and superconductors: The one-dimensional (1D) Su-Schrieffer-Heeger (SSH) model is central to band\ntopology in condensed matter physics, which allows us to understand and design\ntopological states. The Su-Schrieffer-Heeger (SSH) model serves as a basis for\ntopological insulators and provides insights into various topological states.\nIn this letter, we find another mechanism to analogize the SSHmodel by\nintroducing intrinsic spin-orbital coupling (SOC) and in-plane Zeeman field\ninstead of relying on alternating hopping integrals. In our model, the bound\nstates are protected by a quantizedhidden polarization andcharacterized by a\nweak Z2 index (0;01) due to the inversion symmetry I. When the I symmetry is\nbroken, charge pumping is achieved by tuning the polarization. Moreover, by\nintroducing the p + ip superconductor pairing potential, a new topological\nphase called weak topological superconductor (TSC) is identified. The new TSC\nis characterized by a weak Z2 index (0;01) and nonchiral bound states. More\ninterestingly, these nonchiral bound states give rise to a chiral nonlocal\nconductance, which is different from the traditional chiral TSC. Our findings\nnot only innovate the SSH model, but also predict the existence of weak TSC,\nproviding an alternative avenue for further exploration of its transport\nproperties.",
        "positive": "Films of rhombohedral graphite as two-dimensional topological semimetals: Topologically non-trivial states characterized by Berry curvature appear in a\nnumber of materials ranging from spin-orbit-coupling driven topological\ninsulators to graphene. In multivalley conductors, such as mono- and bilayer\ngraphene, despite a zero total Chern number for the entire Brillouin zone,\nBerry curvature with different signs concentrated in different valleys can\naffect the observable material's transport characteristics. Here we consider\nthin films of rhombohedral graphite, which appear to retain truly\ntwo-dimensional properties up to tens of layers of thickness and host\ntwo-dimensional electron states with a large Berry curvature, accompanied by a\ngiant intrinsic magnetic moment carried by electrons. The size of Berry\ncurvature and magnetization in the vicinity of each valley can be controlled by\nelectrostatic gating leading to a tuneable anomalous Hall effect and a peculiar\nstructure of the two-dimensional Landau level spectrum."
    },
    {
        "anchor": "The Group-Theoretical Classification of Some Multiparticle States in the\n  Presence of Magnetic Field and Periodic Potential: The group-theoretical classification of multiparticle states(pairs of\nparticles and charged excitons X^+-) is based on considerations of products of\nirreducible projective representations of the two-dimensional translation\ngroup. The states of a pair particle-antiparticle are non-degenerate, whereas,\nfor a given Born-von Karman period N, degeneracy of pair states is N\nandthree-particle states are N^2-fold degenerated. The symmetrization of states\nwith respect to particles transposition is considered. Three symmetry adapted\nbases for trions are considered: (i) the first is obtained from a direct\nconjugation of three representations; (ii) in the second approach the states of\na electrically neutral pair particle-antiparticle are determined in the first\nstep; (iii) the third possibility is to consider a pair of identical particles\nin the first step. In the discussion presented the Landau gauge A=[0,Hx,0] is\nused, but it is shown that the results obtained are gauge-independent. In\naddition the relation between changes of a chosen gauge and local basis\ntransformations are discussed.",
        "positive": "Supercurrent reversal in Josephson junctions based on bilayer graphene\n  flakes: We investigate the Josephson effect in a bilayer graphene flake contacted by\ntwo monolayer sheet deposited by superconducting electrodes. It is found that\nwhen the electrodes are attached to the different layers of the bilayer, the\nJosephson current is in a $\\pi$ state when the bilayer region is undoped and in\nthe absence of vertical bias. Applying doping or bias to the junction reveals\n$\\pi-0$ transitions which can be controlled by varying the temperature and the\njunction length. The supercurrent reversal here is very different from the\nferromagnetic Josephson junctions where the spin degree of freedom plays the\nkey role. We argue that the scattering processes accompanied by layer and\nsublattice index change give rise to the scattering phases which their effect\nvaries with doping and the bias. Such scattering phases are responsible for the\n$\\pi-0$ transitions. On the other hand if both of the electrodes are coupled to\nthe same layer of the flake or the flake has AA stacking instead of common AB,\nthe junction will be always in $0$ state since layer or sublattice index is not\nchanged."
    },
    {
        "anchor": "Quantized topological magnetoelectric effect of the zero-plateau quantum\n  anomalous Hall state: Topological magnetoelectric effect in a three-dimensional topological\ninsulator is a novel phenomenon, where an electric field induces a magnetic\nfield in the same direction, with a universal coefficient of proportionality\nquantized in units of $e^2/2h$. Here we propose that the topological\nmagnetoelectric effect can be realized in the zero-plateau quantum anomalous\nHall state of magnetic topological insulators or ferromagnet-topological\ninsulator heterostructure. The finite-size effect is also studied numerically,\nwhere the magnetoelectric coefficient is shown to converge to a quantized value\nwhen the thickness of topological insulator film increases. We further propose\na device setup to eliminate the non-topological contributions from the side\nsurface.",
        "positive": "Plasma effects in a micromachined floating-gate high-electron-mobility\n  transistor: We study plasma effects in a micromachined high-electron mobility transistor\n(HEMT) with the microcantilever serving as the gate using the developed a\nmodel. The model accounts for mechanical motion of the microcantilever and\nspatio-temporal variations (plasma effects) of the two-dimensional electron\ngas(2DEG) system in the transistor channel. The microcantilever mechanical\nmotion is described in the point-mass approximation. The hydrodynamic electron\ntransport model is used to describe distributed electron plasma phenomena in\nthe 2DEG system. Using the developed model, we calculated the response function\ncharacterizing the amplitude microcantilever oscillations and the output\nelectric signal as functions of the signal frequency and the bias voltage for\nthe devices with different parameters. We find the voltage dependences of the\nfrequency of the mechanical resonance and its damping. In particular, it is\ndemonstrated that the amplitudes of the mechanical oscillations and output\nelectric signal exhibit pronounced maxima at the bias voltages close to the\nvoltage of the 2DEG channel depletion followed by a steep drop with further\nincrease in the bias voltage."
    },
    {
        "anchor": "Dissipative Quantum Hall Effect in Graphene near the Dirac Point: We report on the unusual nature of nu=0 state in the integer quantum Hall\neffect (QHE) in graphene and show that electron transport in this regime is\ndominated by counter-propagating edge states. Such states, intrinsic to\nmassless Dirac quasiparticles, manifest themselves in a large longitudinal\nresistivity rho_xx > h/e^2, in striking contrast to rho_xx behavior in the\nstandard QHE. The nu=0 state in graphene is also predicted to exhibit\npronounced fluctuations in rho_xy and rho_xx and a smeared zero Hall plateau in\nsigma_xy, in agreement with experiment. The existence of gapless edge states\nputs stringent constraints on possible theoretical models of the nu=0 state.",
        "positive": "Electronic properties of graphene-based bilayer systems: This article reviews the theoretical and experimental work related to the\nelectronic properties of bilayer graphene systems. Three types of bilayer\nstackings are discussed: the AA, AB, and twisted bilayer graphene. This review\ncovers single-electron properties, effects of static electric and magnetic\nfields, bilayer-based mesoscopic systems, spin-orbit coupling, dc transport and\noptical response, as well as spontaneous symmetry violation and other\ninteraction effects. The selection of the material aims to introduce the reader\nto the most commonly studied topics of theoretical and experimental research in\nbilayer graphene."
    },
    {
        "anchor": "Impact of optically pumped non-equilibrium steady states on luminescence\n  emission of atomically-thin semiconductor excitons: The interplay of the non-equivalent corners in the Brillouin zone of\ntransition metal dichalcogenides have been investigated extensively. While\nexperimental and theoretical works contributed to a detailed understanding of\nthe relaxation of selective optical excitations and the related relaxation\nrates, only limited microscopic descriptions of stationary experiments are\navailable so far. In this manuscript we present microscopic calculations for\nthe non-equilibrium steady state properties of excitons during continuous wave\npumping. We find sharp features in photoluminescence excitation spectra and\ndegree of polarization which result from phonon assisted excitonic transitions\ndominating over exciton recombination and intervalley exchange coupling.",
        "positive": "Exploring Spin-Transfer-Torque Devices for Logic Applications: As CMOS nears the end of the projected scaling roadmap, significant effort\nhas been devoted to the search for new materials and devices that can realize\nmemory and logic. Spintronics, is one of the promising directions for the\nPost-CMOS era. While the potential of spintronic memories is relatively well\nknown, realizing logic remains an open and critical challenge. All Spin Logic\n(ASL) is a recently proposed logic style that realizes Boolean logic using\nspin-transfer-torque (STT) devices based on the principle of non-local spin\ntorque. ASL has advantages such as density, non-volatility, and low operating\nvoltage. However, it also suffers from drawbacks such as low speed and static\npower dissipation. Recent work has shown that, in the context of simple\narithmetic circuits (adders, multipliers), the efficiency of ASL can be greatly\nimproved using techniques that utilize its unique characteristics. An\nevaluation of ASL across a broad range of circuits, considering the known\noptimization techniques, is an important next step in determining its\nviability. In this work, we propose a systematic methodology for the synthesis\nof ASL circuits. Our methodology performs various optimizations that benefit\nASL, such as intra-cycle power gating, stacking of ASL nanomagnets, and\nfine-grained logic pipelining. We utilize the proposed methodology to evaluate\nthe suitability of ASL implementations for a wide range of benchmarks viz.\nrandom combinational and sequential logic, digital signal processing circuits,\nand the Leon SPARC3 general-purpose processor. Based on our evaluation, we\nidentify (i) the large current requirement of nanomagnets at fast switching\nspeeds, (ii) the static power dissipation in the all-metallic devices, and\n(iii) the short spin flip length in interconnects as key bottlenecks that limit\nthe competitiveness of ASL."
    },
    {
        "anchor": "Fluorinated graphene films with graphene quantum dots for electronic\n  applications: This work analyzes carrier transport, the relaxation of non-equilibrium\ncharge, and the electronic structure of fluorinated graphene (FG) films with\ngraphene quantum dots (GQDs). The FG films with GQDs were fabricated by means\nof chemical functionalization in an aqueous solution of hydrofluoric acid. High\nfluctuations of potential relief inside the FG barriers have been detected in\nthe range of up to 200 mV. A phenomenological expression that describes the\ndependence of the time of non-equilibrium charge emission from GQDs on quantum\nconfinement levels and film thickness (potential barrier parameters between\nGQDs) is suggested. An increase in the degree of functionalization leads to a\ndecrease in GQD size, the removal of the GQD effect on carrier transport, and\nthe relaxation of non-equilibrium charge. The study of the electronic\nproperties of FG films with GQDs has revealed a unipolar resistive switching\neffect in the films with a relatively high degree of fluorination and a high\ncurrent modulation in transistorlike structures with a lower degree of\nfluorination. 2D films with GQDs are believed to have considerable potential\nfor various electronic applications (nonvolatile memory, 2D connections with\noptical control and logic elements).",
        "positive": "Twisted Heating-Cooling Transition of Near-field Radiation in Drifted\n  Metasurfaces: The magic angle twisted bilayer systems give rise to many exotic phenomena in\ntwo-dimensional electronic or photonic platforms. Here, we study the twisted\nnear-field energy radiation between graphene metasurfaces with nonequilibrium\ndrifted Dirac electrons. Anomalously, we find unconventional radiative flux\nthat directs heat from cold to hot. This far-from-equilibrium phenomenon leads\nto a heating-cooling transition beyond a thermal magic twist angle, facilitated\nby twist-induced photonic topological transitions. The underlying mechanism is\nrelated to the spectrum match and mismatch caused by the cooperation between\nthe non-reciprocal nature of drifted plasmon polaritons and their topological\nfeatures. Furthermore, we report the unintuitive distance dependence of\nradiative energy flux under large twist angles. The near-field radiation\nbecomes thermal insulating when increasing to a critical distance, and\nsubsequently reverses the radiative flux to increase the cooling power as the\ndistance increases further. Our results indicate the promising future of\nnonequilibrium drifted and twisted devices and pave the way towards tunable\nradiative thermal management."
    },
    {
        "anchor": "Ordering effects in 2D hexagonal systems of binary and ternary BCN\n  alloys: We present theoretical study of ordering phenomena in binary $C_{1-x}B_{x}$,\n$C_{1-x}N_{x}$ and ternary $B_{x}C_{1-x-y}N_{y}$ alloys forming\ntwo-dimensional, graphene-like systems. For calculating energy of big systems\n(20 000 atoms in the supercell with periodic boundary conditions assumed)\nempirical Tersoff potential was employed. In order to find equilibrium\ndistribution of different species corresponding to minima of the energy, we use\nMonte Carlo approach in Metropolis regime. We take into consideration wide\nrange of concentrations (1-50%) and temperatures (70-1500 K), to provide more\ncomplete picture. For quantitative description of order, we determine\nWarren-Cowley Short Range Order (SRO) parameters for the first coordination\nshell. This procedure allows us to determine energetically favorable\ncompositions of all alloys, and characterize resulting types of order for both\nbinary and ternary systems.",
        "positive": "Fractionalized Wave Packets from an Artificial Tomonaga-Luttinger Liquid: The model of interacting fermion systems in one dimension known as\nTomonaga-Luttinger liquid (TLL) provides a simple and exactly solvable\ntheoretical framework, predicting various intriguing physical properties.\nEvidence of TLL has been observed as power-law behavior in the electronic\ntransport and momentum-resolved spectroscopy on various types of\none-dimensional (1D) conductors. However, these measurements, which rely on dc\ntransport involving tunneling processes, cannot identify the eigenmodes of the\nTLL, i.e., collective excitations characterized by non-trivial effective charge\ne* and charge velocity v*. The elementary process of charge fractionalization,\na phenomenon predicted to occur at the junction of a TLL and non-interacting\nleads, has not been observed. Here we report time-resolved transport\nmeasurements on an artificial TLL comprised of coupled integer quantum Hall\nedge channels, successfully identifying single charge fractionalization\nprocesses. An electron wave packet with charge e incident from a\nnon-interacting region breaks up into several fractionalized charge wave\npackets at the edges of the artificial TLL region, from which e* and v* can be\ndirectly evaluated. These results are informative for elucidating the nature of\nTLLs and low-energy excitations in the edge channels."
    },
    {
        "anchor": "Topological transitions induced by antiferromagnetism in a thin-film\n  topological insulator: Ferromagnetism in topological insulators (TIs) opens a topologically\nnon-trivial exchange band gap, providing an exciting platform to manipulate the\ntopological order through an external magnetic field. Here, we experimentally\nshow that the surface of an antiferromagnetic thin film can independently\ncontrol the topological order of the top and the bottom surface states of a TI\nthin film through proximity couplings. During the magnetization reversal in a\nfield scan, two intermediate spin configurations stem from unsynchronized\nmagnetic switchings of the top and the bottom AFM/TI interfaces. These magnetic\nconfigurations are shown to result in new topological phases with non-zero\nChern numbers for each surface, introducing two counter-propagating chiral edge\nmodes inside the exchange gap. This change in the number of transport channels,\nas the result of the topological transitions, induces antisymmetric\nmagneto-resistance spikes during the magnetization reversal. With the high Neel\nordering temperature provided by the antiferromagnetic layers, the signature of\nthe induced topological transition persists in transport measurements up to a\ntemperature of around 90 K, a factor of three over the Curie temperature in a\ntypical magnetically doped TI thin film.",
        "positive": "Low B Field Magneto-Phonon Resonances in Single-Layer and Bilayer\n  Graphene: Many-body effects resulting from strong electron-electron and electron-phonon\ninteractions play a significant role in graphene physics. We report on their\nmanifestation in low B field magneto-phonon resonances in high quality\nexfoliated single-layer and bilayer graphene encapsulated in hexagonal boron\nnitride. These resonances allow us to extract characteristic effective Fermi\nvelocities, as high as $1.20 \\times 10^6$ m/s, for the observed \"dressed\"\nLandau level transitions, as well as the broadening of the resonances, which\nincreases with Landau level index."
    },
    {
        "anchor": "Density waves and supersolidity in rapidly rotating atomic Fermi gases: We study theoretically the low-temperature phases of a two-component atomic\nFermi gas with attractive s-wave interactions under conditions of rapid\nrotation. We find that, in the extreme quantum limit, when all particles occupy\nthe lowest Landau level, the normal state is unstable to the formation of\n\"charge\" density wave (CDW) order. At lower rotation rates, when many Landau\nlevels are occupied, we show that the low-temperature phases can be\nsupersolids, involving both CDW and superconducting order.",
        "positive": "Strange effect of disorder on electron transport through a thin film: A novel feature of electron transport is explored through a thin film of\nvarying impurity density with the distance from its surface. The film, attached\nto two metallic electrodes, is described by simple tight-binding model and its\ncoupling to the electrodes is treated through Newns-Anderson chemisorption\ntheory. Quite interestingly it is observed that, in the strong disorder regime\nthe amplitude of the current passing through the film increases with the\nincrease of the disorder strength, while it decreases in the weak disorder\nregime. This anomalous behavior is completely opposite to that of conventional\ndisordered systems. Our results also predict that the electron transport is\nsignificantly influenced by the finite size of the thin film."
    },
    {
        "anchor": "Fragile topological dislocation modes: We here introduce the concept of fragile topological dislocation modes, which\nare localized only in a fraction of a topological phase, while otherwise leak\ninto the bulk continuum. We show that such dislocation modes are hosted in an\nobstructed atomic topological phase in the two-dimensional Su-Schrieffer-Heeger\nmodel, but only in a finite region with an indirect gap at high energy. These\ndislocation modes are realized as chiral pairs at finite energies with\nprotection stemming from a combination of the chiral (unitary particle-hole)\nand the point group (C$_{4v}$) symmetries, but only when the indirect gap is\nopen. In this regime, we corroborate the stability of the defect modes by\nfollowing their localization and also by explicitly adding a weak chemical\npotential disorder. Our findings, therefore, should be consequential for the\nexperimental observation of such modes in designer topological crystals and\nclassical metamaterials.",
        "positive": "Flat-band excitonic states in Kagome lattice on semiconductor surface: Excitonic properties in the Kagome lattice system, which is produced by\nquantum wires on semiconductor surfaces, are investigated by using the exact\ndiagonalization of a tight binding model. It is shown that due to the existence\nof flat bands the binding energy of exciton becomes remarkably large in the\ntwo-dimensional Kagome lattice compared to that in one-dimensional lattice, and\nthe exciton Bohr radius is quite small as large as a lattice constant. We also\ndiscuss the magnetic field effects on the exciton binding energy and the\nstability of exciton against the creation of charged exciton and biexciton."
    },
    {
        "anchor": "Surface Versus Bulk Dirac States Tuning in a Three-Dimensional\n  Topological Dirac Semimetal: Recently, crystalline-symmetry-protected three-dimensional (3D) bulk Dirac\nsemimetal phase has been experimentally identified in a stoichiometric\nhigh-mobility compound, Cd3As2. The Dirac state observed in Cd3As2 has been\nattributed to originate mostly from the bulk state while calculations show that\nthe bulk and surface states overlap over the entire Dirac dispersion energy\nrange. In this study, we unambiguously reveal doping induced evolution of the\nground state of surface and bulk electron dynamics in a 3D Dirac semimetal. We\ndevelop a systematic technique to isolate the surface and bulk states in\nCd3As2, by simultaneously utilizing angle-resolved photoemission spectroscopy\n(ARPES) and in-situ surface deposition. Our experimental results provide a\nmethod for tuning the chemical potential as well as to observe surface states\ndegenerate with bulk states, which will be useful for future applications of 3D\nDirac semimetal.",
        "positive": "A Ballistic Graphene Cooper Pair Splitter: We report an experimental study of Cooper pair splitting in an encapsulated\ngraphene based multiterminal junction in the ballistic transport regime. Our\ndevice consists of two transverse junctions, namely the\nsuperconductor/graphene/superconductor and the normal metal/graphene/normal\nmetal junctions. In this case, the electronic transport through one junction\ncan be tuned by an applied bias along the other. We observe clear signatures of\nCooper pair splitting in the local as well as nonlocal electronic transport\nmeasurements. Our experimental data can be very well described by using a\nmodified Octavio-Tinkham-Blonder-Klapwijk model and a three-terminal beam\nsplitter model."
    },
    {
        "anchor": "Charge occupancy of two interacting electrons on artificial molecules -\n  exact results: We present exact solutions for two interacting electrons on an artificial\natom and on an artificial molecule made by one and two (single level) quantum\ndots connected by ideal leads. Specifically, we calculate the accumulated\ncharge on the dots as function of the gate voltage, for various strengths of\nthe electron-electron interaction and of the hybridization between the dots and\nthe (one-dimensional) leads. With increasing of the (negative) gate voltage,\nthe accumulated charge in the two-electron ground state increases in gradual\nsteps from 0 to 1 and then to 2. The value 0 represents an \"insulating\" state,\nwhere both electrons are bound to shallow states on the impurities. The value\nof 1 corresponds to a \"metal\", with one electron localized on the dots and the\nother extended on the leads. The value of 2 corresponds to another \"insulator\",\nwith both electrons strongly localized. The width of the \"metallic\" regime\ndiverges with strength of the electron-electron interaction for the single dot,\nbut remains very narrow for the double dot. These results are contrasted with\nthe simple Coulomb blockade picture.",
        "positive": "Influence of intermixing at the Ta/CoFeB interface on spin Hall angle in\n  Ta/CoFeB/MgO heterostructures: We investigate the spin Hall effect in perpendicularly magnetized\nTa/Co40Fe40B20/MgO trilayers with Ta underlayers thicker than the spin\ndiffusion length. The crystallographic structures of the Ta layer and Ta/CoFeB\ninterface are examined in detail using X-ray diffraction and transmission\nelectron microscopy. The thinnest Ta underlayer is amorphous, whereas for\nthicker Ta layers a disoriented tetragonal beta-phase appears. Effective\nspin-orbit torques are calculated based on harmonic Hall voltage measurements\nperformed in a temperature range between 15 and 300 K. To account for the\ntemperature dependence of damping-like and field-like torques, we extend the\nspin diffusion model by including an additional contribution from the Ta/CoFeB\ninterface. Based on this approach, the temperature dependence of the spin Hall\nangle in the Ta underlayer and at Ta/CoFeB interface are determined separately.\nThe results indicate an almost temperature-independent spin Hall angle of\ntheta_SH-N = -0.2 in Ta and a strongly temperature-dependent theta_SH-I for the\nintermixed Ta/CoFeB interface."
    },
    {
        "anchor": "Extending spin ice concepts to another geometry: the artificial\n  triangular spin ice: In this work we propose and study a realization of an artificial spin\nice-like system, not based on any real material, in a triangular geometry. At\neach vertex of the lattice, the \"ice-like rule\" dictates that three spins must\npoint inward while the other three must point outward. We have studied the\nsystem's ground-state and the lowest energy excitations as well as the\nthermodynamic properties of the system. Our results show that, despite\nfundamental differences in the vertices topologies as compared to the\nartificial square spin ice, in the triangular array the lowest energy\nexcitations also behave as a kind of Nambu monopoles (two opposite monopoles\nconnected by an energetic string). Indeed, our results suggest that the\nmonopoles charge value may have a universal value while the string tension\ncould be tuned by changing the system's geometry, probably allowing the design\nof systems with different string tensions. Our Monte Carlo results suggest a\nphase transition in the Ising universality class where the mean distance\nbetween monopoles and anti-monopoles increases considerably at the critical\ntemperature. The differences on the vertices topologies seem to facilitate the\nexperimental achievement of the system's ground-state, thereby allowing a more\ndetailed experimental study of the system's properties.",
        "positive": "Temperature-dependence of T1 spin relaxation of single NV centers in\n  nanodiamonds: We report the experimental study of the temperature-dependence of the\nlongitudinal spin relaxation time $T_1$ of single Nitrogen-Vacancy (NV) centers\nhosted in nanodiamonds. To determine the relaxation mechanisms at stake,\nmeasurements of the $T_1$ relaxation time are performed for a set of individual\nNV centers both at room and cryogenic temperatures. The results are consistant\nwith a temperature-dependent relaxation process which is attributed to a\nthermally-activated magnetic noise produced by paramagnetic impurities lying on\nthe nanodiamond surface. These results confirm the existence of surface-induced\nspin relaxation processes occurring in nanodiamonds, which are relevant for\nfuture developments of sensitive nanoscale NV-based quantum sensors."
    },
    {
        "anchor": "Spin-Selective Equilibration among Integer Quantum Hall Edge Channels: The equilibration between quantum Hall edge modes is known to depend on the\ndisorder potential and the steepness of the edge. Modern samples with higher\nmobilities and setups with lower electron temperatures call for a further\nexploration of the topic. We develop a framework to systematically measure and\nanalyze the equilibration of many (up to 8) integer edge modes. Our results\nshow that spin-selective coupling dominates even for non-neighboring channels\nwith parallel spin. Changes in magnetic field and bulk density let us control\nthe equilibration until it is almost completely suppressed and dominated only\nby individual microscopic scatterers. This method could serve as a guideline to\ninvestigate and design improved devices, and to study fractional and other\nexotic states.",
        "positive": "Topological spin Hall effect in antiferromagnets driven by vector N\u00e9el\n  chirality: Spin Hall effect of spin-texture origin is explored theoretically for\nantiferromagnetic (AF) metals. It is found that a vector chirality formed by\nthe N\\'eel vector gives rise to a topological spin Hall effect. This is\ntopological since it is proportional to the winding number counted by in-plane\nvector chirality along the sample edge, which can be nonvanishing for AF merons\nbut not for AF skyrmions. The effect is enhanced when the Fermi level lies near\nthe AF gap, and, surprisingly, at weak coupling with small AF gap. These\nfeatures are confirmed numerically based on the Landauer-B\\\"uttiker formula.\nImportant roles played by nonadiabatic processes and spin dephasing are pointed\nout."
    },
    {
        "anchor": "Field-induced Kosterlitz-Thouless transition in the N=0 Landau level of\n  graphene: At the charge neutral point, graphene exhibits a very unusual high resistance\nmetallic state and a transition to a complete insulating phase in a strong\nmagnetic field. We propose that the current carriers in this state are the\ncharged vortices of the XY valley pseudospin order-parameter, a situation which\nis dual to a conventional thin superconducting film. We study energetics and\nthe stability of this phase in the presence of disorder.",
        "positive": "Mobility engineering and metal-insulator transition in monolayer MoS2: Two-dimensional (2D) materials are a new class of materials with interesting\nphysical properties and ranging from nanoelectronics to sensing and photonics.\nIn addition to graphene, the most studied 2D material, monolayers of other\nlayered materials such as semiconducting dichalcogenides MoS2 or WSe2 are\ngaining in importance as promising insulators and channel materials for\nfield-effect transistors (FETs). The presence of a direct band gap in monolayer\nMoS2 due to quantum mechanical confinement, allows room-temperature\nfield-effect transistors with an on/off ratio exceeding 108. The presence of\nhigh-k dielectrics in these devices enhanced their mobility, but the mechanisms\nare not well understood. Here, we report on electrical transport measurements\non MoS2 FETs in different dielectric configurations. Mobility dependence on\ntemperature shows clear evidence of the strong suppression of charge impurity\nscattering in dual-gate devices with a top-gate dielectric together with phonon\nscattering that shows a weaker than expected temperature dependence. High\nlevels of doping achieved in dual-gate devices also allow the observation of a\nmetal-insulator transition in monolayer MoS2. Our work opens up the way to\nfurther improvements in 2D semiconductor performance and introduces MoS2 as an\ninteresting system for studying correlation effects in mesoscopic systems."
    },
    {
        "anchor": "Slowing hot carrier relaxation in graphene using a magnetic field: A degenerate pump--probe technique is used to investigate the non equilibrium\ncarrier dynamics in multi--layer graphene. Two distinctly different dynamics of\nthe carrier relaxation are observed. A fast relaxation ($\\sim 50$ fs) of the\ncarriers after the initial effect of phase space filling followed by a slower\nrelaxation ($\\sim 4$ ps) due to thermalization. Both relaxation processes are\nless efficient when a magnetic field is applied at low temperatures which is\nattributed to the suppression of the electron-electron Auger scattering due to\nthe non equidistant Landau level spacing of the Dirac fermions in graphene.",
        "positive": "Exact Many-Body Ground States from Decomposition of Ideal Higher Chern\n  Bands: Applications to Chirally Twisted Graphene Multilayers: Motivated by the higher Chern bands of twisted graphene multilayers, we\nconsider flat bands with arbitrary Chern number $C$ with ideal quantum\ngeometry. While $C>1$ bands differ from Landau levels, we show that these bands\nhost exact fractional Chern insulator (FCI) ground states for short range\ninteractions. We show how to decompose ideal higher Chern bands into separate\nideal bands with Chern number $1$ that are intertwined through translation and\nrotation symmetry. The decomposed bands admit an $SU(C)$ action that combines\nreal space and momentum space translations. Remarkably, they also allow for\nanalytic construction of exact many-body ground states, such as generalized\nquantum Hall ferromagnets and FCIs, including flavor-singlet Halperin states\nand Laughlin ferromagnets in the limit of short-range interactions. In this\nlimit, the $SU(C)$ action is promoted to a symmetry on the ground state\nsubspace. While flavor singlet states are translation symmetric, the flavor\nferromagnets correspond to translation broken states and admit charged skyrmion\nexcitations corresponding to a spatially varying density wave pattern. We\nconfirm our analytic predictions with numerical simulations of ideal bands of\ntwisted chiral multilayers of graphene, and discuss consequences for\nexperimentally accessible systems such as monolayer graphene twisted relative\nto a Bernal bilayer."
    },
    {
        "anchor": "NMR Study of Large Skyrmions in Al_{0.13}Ga_{0.87}As Quantum Wells: A nuclear magnetic resonance (NMR) study is reported of multiple (30)\nAl$_{0.13}$Ga$_{0.87}$As quantum well (QW) sample near the Landau level filling\nfactor $\\nu =1$. In these Al$_{0.13}$Ga$_{0.87}$As QWs the effective $g$ factor\nis nearly zero. This can lead to two effects: vanishing electronic polarization\n$(P)$ and skyrmionic excitations composed of a huge number of spins. As small\n$P$ values cause an overlap of the NMR signals from the QW and barriers, a\nspecial technique was employed to allow these two signals to be distinguished.\nThe QW signal corresponds to a small, negative, and very broad distribution of\nspin polarization that exhibits thermally induced depolarization. Such a\ndistribution can be attributed to sample inhomogeneities and/or to large\nskyrmions, the latter possibility being favored by observation of a very fast\n$T_{2}^{-1}$ rate.",
        "positive": "Periodic magnetoconductance fluctuations in triangular quantum dots in\n  the absence of selective probing: We have studied the magnetoconductance of quantum dots with triangular\nsymmetry and areas down to 0.2 square microns, made in a high mobility\ntwo-dimensional electron gas embedded in a GaAs-AlGaAs heterostructure.\nSemiclassical simulations show that the gross features in the measured\nmagnetoconductance are caused by ballistic effects. Below 1 K we observe a\nstrong periodic oscillation, which may be explained in terms of the\nAharanov-Bohm flux quantization through the area of a single classical periodic\norbit. From a numerical and analytical analysis of possible trajectories in\nhard- and soft-walled potentials, we identify this periodic orbit as the\nenscribed triangle. Contrary to other recent experiments, this orbit is not\naccessible by classical processes for the incoming collimated beam."
    },
    {
        "anchor": "Dynamics of the Inductive Single-Electron Transistor: Using a classical equation of motion, dynamics of the phase is analyzed in\nthe Inductive Single-Electron Transistor (L-SET) which is a promising new\nsystem suitable for quantum measurement with ultimate sensitivity and low\nback-action. In a regime of nonlinear dynamics, a shift of the oscillator\nresonant frequency is discovered which has a direct analogy to the switching of\na dc-biased Josephson junction into voltage state. Results are reviewed for the\npredicted charge sensitivity, and it is shown that a performance challenging\nthe best rf-SETs is foreseeable with the new device.",
        "positive": "Obstructed insulators and flat bands in topological phase-change\n  materials: Phase-change materials are ubiquitous in technology because of their ability\nto transition between amorphous and crystalline phases fast and reversibly,\nupon shining light or passing a current. Here we argue that to fully understand\ntheir electronic properties it is necessary to define a novel electronic phase:\nthe amorphous obstructed insulator. It differs from an obstructed insulator\ncrystal in that it presents localized edge or surface states irrespective of\nthe sample termination. Consequently, we show that obstructed amorphous\ninsulators in three-dimensions host a surface two-dimensional flat band,\ndetectable using ARPES. Our work establishes basic models for materials where\ntopological and obstructed properties can be switched on and off externally,\nincluding two-dimensional surface flatbands."
    },
    {
        "anchor": "Measuring Exciton Fine-Structure in Perovskite Nanocrystal Ensembles: Lead-halide perovskite nanocrystals (PNCs) exhibit unique optoelectronic\nproperties, many of which originate from a purported bright-triplet exciton\nfine-structure. A major impediment to measuring this fine-structure is\ninhomogeneous spectral broadening, which has limited most experimental studies\nto single-nanocrystal spectroscopies. It is shown here that the\nlinearly-polarized single-particle selection rules in PNCs are preserved in\nnonlinear spectroscopies of randomly-oriented ensembles. Simulations\nincorporating rotational-averaging demonstrate that techniques such as\ntransient absorption and two-dimensional coherent spectroscopy are capable of\nresolving exciton fine-structure in PNCs, even in the presence of inhomogeneous\nbroadening and orientation disorder.",
        "positive": "Two-dimensional electron scattering in regions of nonuniform spin-orbit\n  coupling: We present a theoretical study of elastic spin-dependent electron scattering\ncaused by a nonuniform Rashba spin-orbit coupling strength. Using the\nspin-generalized method of partial waves the scattering amplitude is exactly\nderived for the case of a circular shape of scattering region. We found that\nthe polarization of the scattered waves are strongly anisotropic functions of\nthe scattering angle. This feature can be utilized to design a good\nall-electric spin-polarizer. General properties of the scattering process are\nalso investigated in the high and low energy limits."
    },
    {
        "anchor": "Surface States Engineering of Metal/MoS2 Contacts Using Sulfur Treatment\n  for Reduced Contact Resistance and Variability: Variability and lack of control in the nature of contacts between metal/MoS2\ninterface is a major bottleneck in the realisation of high-performance devices\nbased on layered materials for several applications. In this letter, we report\non the reduction in Schottky barrier height at metal/MoS2 interface by\nengineering the surface states through sulphur treatment. Electrical\ncharacteristics for back-gated MoS2 field effect transistor structures were\ninvestigated for two high work-function metal contacts Ni and Pd. Contacts on\nMoS2 treated with sulphur exhibited significant improvements in Ohmic nature\nwith concomitant reduction in variability compared to those on untreated MoS2\nfilms leading to a 2x increase in extracted mobility. X-ray Photoelectron\nSpectroscopy (XPS) measurements, Raman Spectroscopy and comparison of threshold\nvoltages indicated absence of additional doping or structural changes due to\nsulphur treatment. The Schottky barrier heights were extracted from\ntemperature-dependent transfer characteristics based on the thermionic current\nmodel. A reduction in barrier height of 80 and 135 meV extracted for Ni/MoS2\nand Pd/MoS2 contacts respectively is hence attributed to the increase in\nsurface states (or stronger Fermi level pinning) due to sulphur treatment. The\ncorresponding charge neutrality levels at metal/MoS2 interface, were extracted\nto be 0.16 eV (0.17 eV) below the conduction band before (after) Sulphur\ntreatment. This first report of surface states engineering in MoS2 leading to\nsuperior contacts is expected to significantly benefit the entire class of\ndevices based on layered 2D materials.",
        "positive": "Spatial and Magnetic Confinement of Massless Dirac Fermions: The massless Dirac fermions and the ease to introduce spatial and magnetic\nconfinement in graphene provide us unprecedented opportunity to explore\nconfined relativistic matter in this condensed-matter system. Here we report\nthe interplay between the confinement induced by external electric fields and\nmagnetic fields of the massless Dirac fermions in graphene. When the magnetic\nlength lB is larger than the characteristic length of the confined electric\npotential lV, the spatial confinement dominates and a relatively small critical\nmagnetic field splits the spatial-confinement-induced atomic-like shell states\nby switching on a pi Berry phase of the quasiparticles. When the lB becomes\nsmaller than the lV, the transition from spatial confinement to magnetic\nconfinement occurs and the atomic-like shell states condense into Landau levels\n(LLs) of the Fock-Darwin states in graphene. Our experiment demonstrates that\nthe spatial confinement dramatically changes the energy spacing between the LLs\nand generates large electron-hole asymmetry of the energy spacing between the\nLLs. These results shed light on puzzling observations in previous experiments,\nwhich hitherto remained unaddressed."
    },
    {
        "anchor": "Broadband, large-area microwave antenna for optically-detected magnetic\n  resonance of nitrogen-vacancy centers in diamond: We report on a microwave planar ring antenna specifically designed for\noptically-detected magnetic resonance (ODMR) of nitrogen-vacancy (NV) centers\nin diamond. It has the resonance frequency at around 2.87 GHz with the\nbandwidth of 400 MHz, ensuring that ODMR can be observed under external\nmagnetic fields up to 100 G without the need of adjustment of the resonance\nfrequency. It is also spatially uniform within the 1-mm-diameter center hole,\nenabling the magnetic-field imaging in the wide spatial range. These features\nfacilitate the experiments on quantum sensing and imaging using NV centers at\nroom temperature.",
        "positive": "Quantum Hall Bilayer as Pseudospin Magnet: We revisit the physics of electron gas bilayers in the quantum Hall regime\n[Nature, 432 (2004) 691; Science, 305 (2004) 950], where transport and\ntunneling measurements provided evidence of a superfluid phase being present in\nthe system. Previously, this behavior was explained by the possible formation\nof a BEC of excitons in the half-filled electron bilayers, where empty states\nplay the role of holes. We discuss the fundamental difficulties with this\nscenario, and propose an alternative approach based on a treatment of the\nsystem as a pseudospin magnet. We show that the experimentally observed\ntunneling peak can be linked to the XY ferromagnet (FM) to Ising\nantiferromagnet (AFM) phase transition of the S=1/2 XXZ pseudospin model,\ndriven by the change in total electron density. This transition is accompanied\nby a qualitative change in the nature of the low energy spin wave dispersion\nfrom a gapless linear mode in the XY-FM phase to a gapped, quadratic mode in\nthe Ising-AFM phase."
    },
    {
        "anchor": "Spin and Charge Signatures of Topological Superconductivity in Rashba\n  Nanowires: We consider a Rashba nanowire with proximity gap which can be brought into\nthe topological phase by tuning external magnetic field or chemical potential.\nWe study spin and charge of the bulk quasiparticle states when passing through\nthe topological transition for open and closed systems. We show, analytically\nand numerically, that the spin of bulk states around the topological gap\nreverses its sign when crossing the transition due to band inversion,\nindependent of the presence of Majorana fermions in the system. This spin\nreversal can be considered as a bulk signature of topological superconductivity\nthat can be accessed experimentally. We find a similar behaviour for the charge\nof the bulk quasiparticle states, also exhibiting a sign reversal at the\ntransition. We show that these signatures are robust against random static\ndisorder.",
        "positive": "Isospin phases of vertically coupled double quantum rings under the\n  influence of perpendicular magnetic fields: Vertically coupled double quantum rings submitted to a perpendicular magnetic\nfield $B$ are addressed within the local spin-density functional theory. We\ndescribe the structure of quantum ring molecules containing up to 40 electrons\nconsidering different inter-ring distances and intensities of the applied\nmagnetic field. When the rings are quantum mechanically strongly coupled, only\nbonding states are occupied and the addition spectrum of the artificial\nmolecules resembles that of a single quantum ring, with some small differences\nappearing as an effect of the magnetic field. Despite the latter has the\ntendency to flatten the spectra, in the strong coupling limit some clear peaks\nare still found even when $B\\neq 0$ that can be interpretated from the\nsingle-particle energy levels analogously as at zero applied field, namely in\nterms of closed-shell and Hund's-rule configurations. Increasing the inter-ring\ndistance, the occupation of the first antibonding orbitals washes out such\nstructures and the addition spectra become flatter and irregular. In the weak\ncoupling regime, numerous isospin oscillations are found as a function of $B$."
    },
    {
        "anchor": "Hyperbolic non-Abelian semimetal: We extend the notion of topologically protected semi-metallic band crossings\nto hyperbolic lattices in negatively curved space. Due to their distinct\ntranslation group structure, such lattices support non-Abelian Bloch states\nwhich, unlike conventional Bloch states, acquire a matrix-valued Bloch factor\nunder lattice translations. Combining diverse numerical and analytical\napproaches, we uncover a quartic scaling in the density of states at low\nenergies, and illuminate a nodal manifold of codimension five in the reciprocal\nspace. The nodal manifold is topologically protected by a non-zero second Chern\nnumber, reminiscent of the characterization of Weyl nodes by the first Chern\nnumber.",
        "positive": "Graphene edge structures: Folding, scrolling, tubing, rippling and\n  twisting: Conventional three-dimensional crystal lattices are terminated by surfaces,\nwhich can demonstrate complex rebonding and rehybridisation, localised strain\nand dislocation formation. Two dimensional crystal lattices, of which graphene\nis the archetype, are terminated by lines. The additional available dimension\nat such interfaces opens up a range of new topological interface possibilities.\nWe show that graphene sheet edges can adopt a range of topological distortions\ndepending on their nature. Rehybridisation, local bond reordering, chemical\nfunctionalisation with bulky, charged, or multi-functional groups can lead to\nedge buckling to relieve strain, folding, rolling and even tube formation. We\ndiscuss the topological possibilities at a 2D graphene edge, and under what\ncircumstances we expect different edge topologies to occur. Density functional\ncalculations are used to explore in more depth different graphene edge types."
    },
    {
        "anchor": "Excitations from Filled Landau Levels in Graphene: We consider graphene in a strong perpendicular magnetic field at zero\ntemperature with an integral number of filled Landau levels and study the\ndispersion of single particle-hole excitations. We first analyze the two-body\nproblem of a single Dirac electron and hole in a magnetic field interacting via\nCoulomb forces. We then turn to the many-body problem, where particle-hole\nsymmetry and the existence of two valleys lead to a number of effects peculiar\nto graphene. We find that the coupling together of a large number of low-lying\nexcitations leads to strong many-body corrections, which could be observed in\ninelastic light scattering or optical absorption. We also discuss in detail how\nthe appearance of different branches in the exciton dispersion is sensitive to\nthe number of filled spin and valley sublevels.",
        "positive": "Mechanism of Thermal Conductivity Reduction in Few-Layer Graphene: Using the linearized Boltzmann transport equation and perturbation theory, we\nanalyze the reduction in the intrinsic thermal conductivity of few-layer\ngraphene sheets accounting for all possible three-phonon scattering events.\nEven with weak coupling between layers, a significant reduction in the thermal\nconductivity of the out-of-plane acoustic modes is apparent. The main effect of\nthis weak coupling is to open many new three-phonon scattering channels that\nare otherwise absent in graphene. However, reflection symmetry is only weakly\nbroken with the addition of multiple layers, and ZA phonons still dominate\nthermal conductivity. We also find that reduction in thermal conductivity is\nmainly caused by lower contributions of the higher-order overtones of the\nfundamental out-of-plane acoustic mode. The results compare remarkably well\nover the entire temperature range with measurements of graphene and graphite."
    },
    {
        "anchor": "Single-qubit gates in two steps with rotation axes in a single plane: Any single-qubit unitary operation or quantum gate can be considered a\nrotation. Typical experimental implementations of single-qubit gates involve\ntwo or three fixed rotation axes, and up to three rotation steps. Here we show\nthat, if the rotation axes can be tuned arbitrarily in a fixed plane, then two\nrotation steps are sufficient for implementing a single-qubit gate, and one\nrotation step is sufficient for implementing a state transformation. The\nresults are relevant for \"exchange-only\" logical qubits encoded in three-spin\nblocks, which are important for universal quantum computation in decoherence\nfree subsystems and subspaces.",
        "positive": "Direct measurement of short-range forces with a levitated nanoparticle: Short-range forces have important real-world relevance across a range of\nsettings in the nano world, from colloids and possibly for protein folding to\nnano-mechanical devices, but also for detection of weak long-range forces, such\nas gravity, at short distances and of candidates to solve the problem of dark\nenergy. Short-range forces, such as Casimir-Polder or van der Waals are in\ngeneral difficult to calculate as a consequence of their non-additive nature,\nand challenging to measure due to their small magnitude - especially for\ncharged particles where dispersion forces are normally many orders of magnitude\nsmaller than electrostatic image forces. Therefore short-range forces have\nrepresented a continuing theoretical and experimental challenge over the last\nhalf-century. Here we report on experiments with a single glass nanoparticle\nlevitated in close proximity to a neutral silicon surface in vacuum, which\nallow for direct measurement of short-range forces in a new distance and\nsensitivity regime - outperforming existing force microscopies."
    },
    {
        "anchor": "Strong modulation of spin currents in bilayer graphene by static and\n  fluctuating proximity exchange fields: Two dimensional (2D) materials provide a unique platform to explore the full\npotential of magnetic proximity driven phenomena, which can be further used for\napplications in next generation spintronic devices. Of particular interest is\nto understand and control spin currents in graphene by the magnetic exchange\nfield of a nearby ferromagnetic material in graphene/ferromagnetic-insulator\n(FMI) heterostructures. Here, we present the experimental study showing the\nstrong modulation of spin currents in graphene layers by controlling the\ndirection of the exchange field due to FMI magnetization. Owing to clean\ninterfaces, a strong magnetic exchange coupling leads to the experimental\nobservation of complete spin modulation at low externally applied magnetic\nfields in short graphene channels. Additionally, we discover that the graphene\nspin current can be fully dephased by randomly fluctuating exchange fields.\nThis is manifested as an unusually strong temperature dependence of the\nnon-local spin signals in graphene, which is due to spin relaxation by\nthermally-induced transverse fluctuations of the FMI magnetization.",
        "positive": "Towards the understanding of the origin of charge-current-induced spin\n  voltage signals in the topological insulator Bi$_2$Se$_3$: Topological insulators provide a new platform for spintronics due to the spin\ntexture of the surface states that are topologically robust against elastic\nbackscattering. Here, we report on an investigation of the measured voltage\nobtained from efforts to electrically probe spin-momentum locking in the\ntopological insulator Bi$_2$Se$_3$ using ferromagnetic contacts. Upon inverting\nthe magnetization of the ferromagnetic contacts, we find a reversal of the\nmeasured voltage. Extensive analysis of the bias and temperature dependence of\nthis voltage was done, considering the orientation of the magnetization\nrelative to the current. Our findings indicate that the measured voltage can\narise due to fringe-field-induced Hall voltages, different from current-induced\nspin polarization of the surface state charge carriers, as reported recently.\nUnderstanding the nontrivial origin of the measured voltage is important for\nrealizing spintronic devices with topological insulators."
    },
    {
        "anchor": "Gate tunable quantum transport in double layer graphene: We analyze the effect of screening provided by the additional graphene layer\nin double layer graphene heterostructures (DLGs) on transport characteristics\nof DLG devices in the metallic regime. The effect of gate-tunable charge\ndensity in the additional layer is two-fold: it provides screening of the\nlong-range potential of charged defects in the system, and screens out Coulomb\ninteractions between charge carriers. We find that the efficiency of defect\ncharge screening is strongly dependent on the concentration and location of\ndefects within the DLG. In particular, only a moderate suppression of\nelectron-hole puddles around the Dirac point induced by the high concentration\nof remote impurities in the silicon oxide substrate could be achieved. A\nstronger effect is found on the elastic relaxation rate due to charged defects\nresulting in mobility strongly dependent on the electron denisty in the\nadditional layer of DLG. We find that the quantum interference correction to\nthe resistivity of graphene is also strongly affected by screening in DLG. In\nparticular, the dephasing rate is strongly suppressed by the additional\nscreening that supresses the amplitude of electron-electron interaction and\nreduces the diffusion time that electrons spend in proximity of each other. The\nlatter effect combined with screening of elastic relaxation rates results in a\npeculiar gate tunable weak-localization magnetoresistance and quantum\ncorrection to resistivity. We propose suitable experiments to test our theory\nand discuss the possible relevance of our results to exisiting data.",
        "positive": "Frequency dependent polarizability of small metallic grains: We study the dynamic electronic polarizability of a single nano-scale\nspherical metallic grain using quantum mechanical approach. We introduce the\nmodel for interacting electrons bound in the grain allowing us numerically to\ncalculate the frequency dependence of the polarizability of grains of different\nsizes. We show that within this model the main resonance peak corresponding to\nthe surface plasmon mode is blue-shifted and some minor secondary resonances\nabove and below the main peak exist. We study the behavior of blue shift as a\nfunction of grain size and compare our findings with the classical\npolarizability and with other results in the literature."
    },
    {
        "anchor": "Floquet multi-gap topology: Non-Abelian braiding and anomalous Dirac\n  string phase: Topological phases of matter span a wide area of research shaping fundamental\npursuits and offering promise for future applications. While a significant\nfraction of topological materials has been characterized using symmetry\nrequirements of wave functions, the past two years have witnessed the rise of\nnovel multi-gap dependent topological states, the properties of which go beyond\nthese approaches and are yet to be fully explored. Thriving upon these\ninsights, we report on uncharted anomalous phases and properties that can only\narise in out-of-equilibrium Floquet settings. In particular, we identify\nFloquet-induced non-Abelian braiding mechanisms, which in turn lead to a phase\ncharacterized by an anomalous Euler class, the prime example of a multi-gap\ntopological invariant. Most strikingly, we also retrieve the first example of\nan `anomalous Dirac string phase'. This gapped out-of-equilibrium phase\nfeatures an unconventional Dirac string configuration that physically manifests\nitself via anomalous edge states on the boundary. Our results therefore not\nonly provide a stepping stone for the exploration of intrinsically dynamical\nand experimentally viable multi-gap topological phases, but also demonstrate a\npowerful way to observe these non-Abelian processes notably in quantum\nsimulators.",
        "positive": "Quantum phase transitions in two-dimensional systems: Experimental data on quantum phase transitions in two-dimensional systems\n(superconductor-insulator, metal-insulator, and transitions under conditions of\ninteger quantum Hall effect) are critically analyzed."
    },
    {
        "anchor": "Distributions of the Conductance and its Parametric Derivatives in\n  Quantum Dots: Full distributions of conductance through quantum dots with single-mode leads\nare reported for both broken and unbroken time-reversal symmetry. Distributions\nare nongaussian and agree well with random matrix theory calculations that\naccount for a finite dephasing time, $\\tau_\\phi$, once broadening due to finite\ntemperature $T$ is also included. Full distributions of the derivatives of\nconductance with respect to gate voltage $P(dg/dV_g)$ are also investigated.",
        "positive": "Alkali-metal-induced Fermi level and two dimensional electrons at\n  cleaved InAs(110) surfaces: Low-temperature Hall measurements have been performed on two-dimensional\nelectron gases (2DEGs) induced by deposition of Cs or Na on in situ cleaved\nsurfaces of p-type InAs. The surface donor level, at which the Fermi energy of\nthe 2DEG is pinned, is calculated from the observed saturation surface electron\ndensity using a surface potential determined self-consistently. The results are\ncompared to those of previous photoelectron spectroscopy measurements."
    },
    {
        "anchor": "Phonon-induced Floquet second-order topological phases protected by\n  space-time symmetries: The co-existence of spatial and non-spatial symmetries together with\nappropriate commutation/anticommutation relations between them can give rise to\nstatic higher-order topological phases, which host gapless boundary modes of\nco-dimension higher than one. Alternatively, space-time symmetries in a Floquet\nsystem can also lead to anomalous Floquet boundary modes of higher\nco-dimensions, presumably with alterations in the commutation/anticommutation\nrelations with respect to non-spatial symmetries. We show how a coherently\nexcited phonon mode can be used to promote a spatial symmetry with which the\nstatic system is always trivial, to a space-time symmetry which supports\nnon-trivial Floquet higher-order topological phase. We present two examples --\none in class D and another in class AIII where a coherently excited phonon mode\npromotes the reflection symmetry to a time-glide symmetry such that the\ncommutation/anticommutation relations between spatial and non-spatial\nsymmetries are modified. These altered relations allow the previously trivial\nsystem to host gapless modes of co-dimension two at reflection-symmetric\nboundaries.",
        "positive": "Imbert-Fedorov shift in Weyl semimetals: Dependence on monopole charge\n  and intervalley scattering: The Imbert-Fedorov (IF) shift in optics describes the transverse shift of\nlight beams at the reflection interface. Recently, the IF shift of Weyl\nfermions at the interface between Weyl semimetals (WSMs) with single monopole\ncharge has been studied. Here, we study the IF shift at the interface between\ntwo WSMs, each of which is carrying an arbitrary integer monopole charge. We\nfind a general relation between the monopole charges of the two WSMs and the IF\nshift. In particular, the IF shift is proportional to the monopole charge if\nboth WSMs have the same one. Our results can be used to infer the topology of\nthe materials by experimentally measuring their IF shift. Furthermore, we\nconsider the possibility that the Weyl fermions are scattered to other Weyl\ncones during the reflection, which results in qualitatively different behavior\nof the IF shift. While we use a quantum mechanical approach to solve the\nproblem, semiclassical equations of motion and the conservation of total\nangular momentum can help us intuitively interpret our results in special\ncases."
    },
    {
        "anchor": "Spin Distribution in Diffraction Pattern of Two-dimensional Electron Gas\n  with Spin-orbit Coupling: Spin distribution in the diffraction pattern of two-dimensional electron gas\nby a split gate and a quantum point contact is computed in the presence of the\nspin-orbit coupling. After diffracted, the component of spin perpendicular to\nthe two-dimensional plane can be generated up to 0.42 $\\hbar$. The non-trivial\nspin distribution is the consequence of a pure spin current in the transverse\ndirection generated by the diffraction. The direction of the spin current can\nbe controlled by tuning the chemical potential.",
        "positive": "Weak interaction between germanene and GaAs(0001) by H intercalation: A\n  route to exfoliation: The epitaxial growth of germanene on semiconducting GaAs(0001) substrate is\nstudied using $ab$-$initio$ calculations. The interaction of the germanene is\nfound to be minimum with the substrate. Our obtained results strongly indicate\nthat it is possible to take off germanene from the substrate to make it free\nstanding. We demonstrate a methods to achieve this aim. We also address the\nelectronic structure of germanene on GaAs(0001) substrate and found to be the\nDirac cone shift above the Fermi level with the spltting of 160 meV.\nForthermore, we calculate the band structure of the free standing germanene\nwith and without substrate and found band gap of 24 meV due to the intrinsic\nspin orbit coupling."
    },
    {
        "anchor": "Amplitude and phase effects in Josephson qubits driven by a biharmonic\n  electromagnetic field: We investigate the amplitude and phase effects of qubit dynamics and\nexcited-state population under the influence of a biharmonic control field. It\nis demonstrated that the biharmonic driving field can have a significant effect\non the behavior of quasi-energy level crossing as well as on multiphoton\ntransitions. Also, the interference pattern for the populations of qubit\nexcited states is sensitive to the signal parameters. We discuss the\npossibility of using these effects for manipulating qubit states and\ncalibrating nanosecond pulses.",
        "positive": "Quantum magnetoelectric effect in molecular crystal Dy$_3$: Magnetoelectric properties of a molecular crystal formed by dysprosium\ntriangular clusters are investigated. The effective spin-electric Hamiltonian\nis derived on the base of developed quantum mechanical model of the cluster\nspin structure. The magnetoelectric contribution to the free energy of the\ncrystal is calculated. The analysis reveals several distinctive features of the\nmagnetoelectric effect, which are not typical for conventional paramagnetic\nsystems at low temperatures. The peculiarities are explained by the chirality\nof the dysprosium core of the molecules."
    },
    {
        "anchor": "Spatial Analogue of Quantum Spin Dynamics via Spin-Orbit Interaction: We map electron spin dynamics from time to space in quantum wires with\nspatially uniform and oscillating Rashba spin-orbit coupling. The presence of\nthe spin-orbit interaction introduces pseudo-Zeeman couplings of the electron\nspins to effective magnetic fields. We show that by periodically modulating the\nspin-orbit coupling along the quantum wire axis, it is possible to create the\nspatial analogue of spin resonance, without the need for any real magnetic\nfields. The mapping of time-dependent operations onto a spatial axis suggests a\nnew mode for quantum information processing in which gate operations are\nencoded into the band structure of the material. We describe a realization of\nsuch materials within nanowires at the interface of LaAlO3/SrTiO3\nheterostructures.",
        "positive": "Semiclassical dynamics of domain walls in the one-dimensional Ising\n  ferromagnet in a transverse field: We investigate analytically and numerically the dynamics of domain walls in a\nspin chain with ferromagnetic Ising interaction and subject to an external\nmagnetic field perpendicular to the easy magnetization axis (transverse field\nIsing model). The analytical results obtained within the continuum\napproximation and numerical simulations performed for discrete classical model\nare used to analyze the quantum properties of domain walls using the\nsemiclassical approximation. We show that the domain wall spectrum shows a band\nstructure consisting of 2$S$ non-intersecting zones."
    },
    {
        "anchor": "Magnetism and structure at a vacancy in graphene: The electronic structure, bonding and magnetism in graphene containing\nvacancies are studied using density-functional methods. The single-vacancy\ngraphene ground state is spin polarized and structurally flat. The unpolarized\nstate is non planar only for finite segments. Systems containing periodic\narrays of vacancies displays magnetic transitions and metal-insulator\ntransitions.",
        "positive": "Spiral orientational order in quantum Hall skyrmion lattices: We investigate the existence of spiral ordering in the planar spin\norientation of skyrmions localised on a face centered rectangular lattice\n(FCRL). We use the non-linear sigma model (NLSM) to numerically calculate the\nminimum energy configurations of this lattice around the $\\nu=1$ quantum Hall\nground state. Our variational ansatz contains an angle $\\theta$, characterising\nthe FCRL and an angle $q$, characterising the orientational order. As $\\nu$ is\nincreased towards one, there is a smooth transition from the triangular lattice\n(TL) characterised by $(\\theta,q) = (120^o,120^o)$ to FCRLs with spiral\norientational order. The novel feature we find is that these phases are\ncharacterised by $\\theta, q)$ values such that $\\theta+q = 240^o$ (same as the\nTL phase). As $\\nu$ incresaes further towards one, there is a sharp transition\nfrom the FCRLs to the square lattice (SL), characterised by\n$(\\theta,q)=(90^o,180^o)$. Consequently, the parameter $\\theta+q$ jumps sharply\nat the FCRL-SL transition and can serve as an order parameter to characterise\nit."
    },
    {
        "anchor": "Generation and detection of non-Abelian matrix Berry phases through\n  manipulation of electric confinement potential of a semiconductor quantum dot: A matrix Berry phase can be generated and detected by {\\it all electric\nmeans} in II-VI or III-V n-type semiconductor quantum dots by changing the\nshape of the confinement potential. This follows from general symmetry\nconsiderations in the presence of spin-orbit coupling terms. The resulting 2 x\n2 matrix Berry phase can be characterized by two numbers of geometric origin.\nWe investigate how these parameters depend on the shape and area of closed\nadiabatic paths. We suggest how the matrix Berry phase may be detected in\ntransport measurements.",
        "positive": "Decoherence in semiconductor cavity QED systems due to phonon scattering: We investigate the effect of electron-phonon interactions on the coherence\nproperties of single photons emitted from a semiconductor cavity QED system,\ni.e. a quantum dot embedded in an optical cavity. The degree of\nindistinguishability, governing the quantum mechanical interference between two\nsingle photons, is calculated as a function of important parameters describing\nthe cavity QED system and the phonon reservoir, e.g. cavity quality factor,\nlight-matter coupling strength, temperature and phonon lifetime. We show that\nnon-Markovian effects play an important role in determining the coherence\nproperties for typical parameter values and establish the conditions under\nwhich a Markovian approximation may be applied. The calculations are performed\nusing a recently developed second order perturbation theory, the limits of\nvalidity of which are established by comparing to an exact diagonalization\napproach. We find that for large cavity decay rates the perturbation theory may\nbreak down."
    },
    {
        "anchor": "High-frequency EPR study on Cu$_4$Cu- and Co$_4$Co-metallacrown\n  complexes: High-frequency/high-field electron paramagnetic resonance studies on two\nhomo-nuclear 12-MC-4 metallacrown complexes Cu$_4$Cu and Co$_4$Co are\npresented. For Cu$_4$Cu, our data imply axial-type $g$-anisotropy with $g_{x}$\n= 2.03 $\\pm$ 0.01, $g_{y}$ = 2.04 $\\pm$ 0.01, and $g_{z}$ = 2.23 $\\pm$ 0.01,\nyielding $g=2.10 \\pm 0.02$. No significant zero field splitting (ZFS) of the\nground state mode is observed. In Co$_4$Co, we find a m$_S$ = $\\pm$3/2 ground\nstate with $g=2.66$. The data suggest large anisotropy $D$ of negative sign.",
        "positive": "Chiral anomaly enhancement and photo-irradiation effects in multi-band\n  touching fermion systems: Multi-band touchings together with the emergence of fermions exhibiting\nlinear dispersions have recently been predicted and realized in various\nmaterials. We first investigate the Adler-Bell-Jackiw chiral anomaly in these\nmulti-band touching semimetals when they are described by the pseudospin\noperator in high dimensional representation. By evaluating the Chern number, we\nshow that the anomalous Hall effect is enhanced depending on the magnitude of\nthe pseudospin. It is also confirmed by the analysis of the Landau levels when\nmagnetic field is applied. Namely, charge pumping occurs from one multi-band\ntouching point to another through multi-channel Landau levels in the presence\nof parallel electric and magnetic fields. We also show a pair annihilation of\ntwo multi-band touching points by photo-irradiation. Furthermore, we propose\ngeneralizations of Dirac semimetals, multiple-Weyl semimetals and loop-nodal\nsemimetals to those composed of fermions carrying pseudospins in high\ndimensional representation. Finally we investigate the 3-band touching\nprotected by the $% C_{3}$ symmetry. We show that the 3-band touching point is\nbroken into two Weyl points by photo-irradiation."
    },
    {
        "anchor": "Gate-defined superconducting channel in magic-angle twisted bilayer\n  graphene: Magic-angle twisted bilayer graphene (MATBG) combines in one single material\ndifferent phases like insulating, metallic and superconducting. These phases\nand their in-situ tunability make MATBG an important platform for the\nfabrication of superconducting devices. We realize a split gate-defined\ngeometry which enables us to tune the width of a superconducting channel formed\nin MATBG. We observe a smooth transition from superconductivity to highly\nresistive transport by progressively reducing the channel width using the split\ngates or by reducing the density in the channel. Using the gate-defined\nconstriction, we control the flow of the supercurrent, either guiding it\nthrough the constriction or throughout the whole device or even blocking its\npassage completely. This serves as a foundation for developing quantum\nconstriction devices like superconducting quantum point contacts, quantum dots,\nand Cooper-pair boxes in MATBG.",
        "positive": "Rectification in Luttinger liquids: We investigate the rectification of an ac bias in Luttinger liquids in the\npresence of an asymmetric potential (the ratchet effect). We show that strong\nrepulsive electron interaction enhances the ratchet current in comparison with\nFermi liquid systems, and the I-V curve is strongly asymmetric in the\nlow-voltage regime even for a weak asymmetric potential. At higher voltages the\nratchet current exhibits an oscillatory voltage dependence."
    },
    {
        "anchor": "Charge ordering and interlayer phase coherence in quantum Hall\n  superlattices: The possibility of the existence of states with a spontaneous interlayer\nphase coherence in multilayer electron systems in a high perpendicular to the\nlayers magnetic field is investigated. It is shown that phase coherence can be\nestablished in such systems only within individual pairs of adjacent layers,\nwhile such coherence does not exist between layers of different pairs. The\nconditions for stability of the state with interlayer phase coherence against\ntransition to a charge-ordered state are determined. It is shown that in the\nsystem with the number of layers N\\leq 10 these conditions are satisfied at any\nvalue of the interlayer distance d. For N>10 there are two intervals of\nstability: at sufficiently large and at sufficiently small d. For N\\to \\infty\nthe stability interval in the region of small d vanishes",
        "positive": "Enhanced spin accumulation at room temperature in graphene spin valves\n  with amorphous carbon interfacial layers: We demonstrate a large enhancement of the spin accumulation in monolayer\ngraphene following electron-beam induced deposition of an amorphous carbon\nlayer at the ferromagnet-graphene interface. The enhancement is 10^4-fold when\ngraphene is deposited onto poly(methyl metacrylate) (PMMA) and exposed with\nsufficient electron-beam dose to cross-link the PMMA, and 10^3-fold when\ngraphene is deposited directly onto SiO2 and exposed with identical dose. We\nattribute the difference to a more efficient carbon deposition in the former\ncase due to an increase in the presence of compounds containing carbon, which\nare released by the PMMA. The amorphous carbon interface can sustain very large\ncurrent densities without degrading, which leads to very large spin\naccumulations exceeding 500 microeVs at room temperature."
    },
    {
        "anchor": "Emergence of massless Dirac fermions in graphene's Hofstadter butterfly\n  at switches of the quantum Hall phase connectivity: The fractal spectrum of magnetic minibands (Hofstadter butterfly), induced by\nthe moir\\'e super- lattice of graphene on an hexagonal crystal substrate, is\nknown to exhibit gapped Dirac cones. We show that the gap can be closed by\nslightly misaligning the substrate, producing a hierarchy of conical\nsingularities (Dirac points) in the band structure at rational values Phi =\n(p/q)(h/e) of the magnetic flux per supercell. Each Dirac point signals a\nswitch of the topological quantum number in the connected component of the\nquantum Hall phase diagram. Model calculations reveal the scale invariant\nconductivity sigma = 2qe^2 / pi h and Klein tunneling associated with massless\nDirac fermions at these connectivity switches.",
        "positive": "Collective excitations in two-component one-dimensional massless Dirac\n  plasma: We study spectra of long wavelength plasma oscillations in a system of two\nenergy splitted one-dimensional (1D) massless Dirac fermion subbands coupled by\nspin-orbit interaction. Such a system may be formed by edge subbands in\nsemiconducting transition metal dichalcogenide monolayers. Intrasubband\ntransitions of massless Dirac fermions give rise to optical and acoustic\ngapless branches of intrasubband 1D plasmons. We reveal that the optical branch\nis of quantum character with group velocity being inverse proportional to\nsquare root of the Planck constant, whereas the acoustic branch is classical\none with group velocity proportional to geometric mean of the edge subband\nvelocities. Spin-orbit interaction, allowing intersubband transitions in the\nsystem, results in emergence of two branches of intersubband 1D plasmons: upper\nand lower ones. The upper and lower branches are gapped at small wave vectors\nand evolve with positive and negative group velocities, respectively, from\nenergy splitting of the edge subbands at Fermi-level. The both intersubband\nbranches adjoin intersubband single particle excitation continuum from above,\nwhile in case of the edge subbands with unequal velocities the lower one\nexperiences Landau damping at small wave vectors. In addition, the lower\nbranch, attaining zero frequency at a non-zero wave vector, alters its group\nvelocity from negative to positive one."
    },
    {
        "anchor": "Seeding ice growth at ambient conditions using nano graphene oxide: Water wetting on a hydrophobic surface at ambient conditions is disallowed by\nthe nonpolar nature of the surface and high vapor pressure of water. However,\nthe presence of sub-millimeter sized hydrophilic patches allows the waxy wings\nof desert beetles to become wettable by morning mist. Here, we show that a\nsprinkle of graphene oxide nanoflakes (nanoGOs) is effective in condensing\nwater nanodroplets and seeding ice epitaxy on graphite at ambient conditions.\nBy controlling relative humidity and nanoGO density, we are able to study the\nformation of a complete ice wetting layer on a time scale of 20 hours. This\npresents an unprecedented opportunity to visualize ice nucleation and growth in\nreal time using non-contact atomic force microscopy. The stages of\ncrystallization, as proposed by Ostwald in 1897, is fully unfolded at a\nmicroscopic level for the first time. We obtain real-time imaging of sequential\nphase transition from amorphous ice to a transient cubic ice Ic stage and\nfinally to the stable hexagonal ice Ih. Most interestingly, we discover that\nice nucleation and growth can be influenced by modifying the functional groups\nof nanoGO, and by intermolecular hydrogen-bonding between nanoGOs. This affords\na strategy to control heterogenous ice nucleation and snow crystal formation.",
        "positive": "Cross-correlation mediated by Majorana island with finite charging\n  energy: Based on the many-particle-number-state treatment for transport through a\npair of Majorana zero modes (MZMs) which are coupled to the leads via two\nquantum dots, we identify that the reason for zero cross correlation of\ncurrents at uncoupling limit between the MZMs is from a degeneracy of the\nteleportation and the Andreev process channels. We then propose a scheme to\neliminate the degeneracy by introducing finite charging energy on the Majorana\nisland which allows for coexistence of the two channels. We find nonzero cross\ncorrelation established even in the Majorana uncoupling limit (and also in the\nsmall charging energy limit), which demonstrates well the teleportation or\nnonlocal nature of the MZMs. More specifically, the characteristic structure of\ncoherent peaks in the power spectrum of the cross correlation is analyzed to\nidentify the nonlocal and coherent coupling mechanism between the MZMs and the\nquantum dots. We also display the behaviors of peak shift with variation of the\nMajorana coupling energy, which can be realized by modulating parameters such\nas the magnetic field."
    },
    {
        "anchor": "The effect of Landau-Zener dynamics on phonon lasing: Optomechanical systems couple light to the motion of nanomechanical objects.\nIntriguing new effects are observed in recent experiments that involve the\ndynamics of more than one optical mode. There, mechanical motion can stimulate\nstrongly driven multi-mode photon dynamics that acts back on the mechanics via\nradiation forces. We show that even for two optical modes\nLandau-Zener-Stueckelberg oscillations of the light field drastically change\nthe nonlinear attractor diagram of the resulting phonon lasing oscillations.\nOur findings illustrate the generic effects of Landau-Zener physics on\nback-action induced self-oscillations.",
        "positive": "Response functions and superfluid density in a weakly interacting Bose\n  gas with non-quadratic dispersion: Motivated by the experimental search for Bose condensation of quasiparticles\nin semiconductors, the response functions of a weakly interacting Bose gas,\nwith isotropic but non-quadratic dispersion, are considered. Non-quadratic\ndispersion modifies the definition of particle current, and leads to modified\nsum rules for the current-current response function. The effect of these\nmodifications on the Berezhinski-Kosterlitz-Thouless transition is discussed."
    },
    {
        "anchor": "Nonlinear Transport through NS Junctions due to Imperfect Andreev\n  Reflection: We investigate a normal metal -- superconductor (point) contact in the limit\nwhere the number of conducting channels in the metallic wire is reduced to few\nchannels. As the effective Fermi energy drops below the gap energy, a\nconducting band with a width twice the Fermi energy is formed. Depending on the\nmode of operation, the conduction band can be further squeezed, leading to\nvarious non-linear effects in the current-voltage characteristics such as\ncurrent saturation, a N-shaped negative differential resistance, bistability,\nand hysteresis.",
        "positive": "Spontaneous symmetry breaking in a polariton and photon laser: We report on the simultaneous observation of spontaneous symmetry breaking\nand long-range spatial coherence both in the strong and the weak-coupling\nregime in a semiconductor microcavity. Under pulsed excitation, the formation\nof a stochastic order parameter is observed in polariton and photon lasing\nregimes. Single-shot measurements of the Stokes vector of the emission exhibit\nthe buildup of stochastic polarization. Below threshold, the polarization noise\ndoes not exceed 10%, while above threshold we observe a total polarization of\nup to 50% after each excitation pulse, while the polarization averaged over the\nensemble of pulses remains nearly zero. In both polariton and photon lasing\nregimes, the stochastic polarization buildup is accompanied by the buildup of\nspatial coherence. We find that the Landau criterion of spontaneous symmetry\nbreaking and Penrose-Onsager criterion of long-range order for Bose-Einstein\ncondensation are met in both polariton and photon lasing regimes."
    },
    {
        "anchor": "Emergent of Majorana Fermion mode and Dirac Equation in Cavity Quantum\n  Electrodynamics: We present the results of low lying excitation of coupled optical cavity\narrays. We derive the Dirac equation for this system and explain the existence\nof Majorana fermion mode in the system. We present quite a few analytical\nrelations between the Rabi frequency oscillation and the atom-photon coupling\nstrength to achieve the different physical situation of our study and also the\ncondition for massless excitation in the system. We present several analytical\nrelations between the Dirac spinor field, order and disorder operators for our\nsystems. We also show that the Luttinger liquid physics is one of the intrinsic\nconcept in our system.",
        "positive": "An elongated quantum dot as a distributed charge sensor: Increasing the separation between semiconductor quantum dots offers scaling\nadvantages by fa- cilitating gate routing and the integration of sensors and\ncharge reservoirs. Elongated quantum dots have been utilized for this purpose\nin GaAs heterostructures to extend the range of spin-spin interactions. Here,\nwe study a metal-oxide-semiconductor (MOS) device where two quantum dot arrays\nare separated by an elongated quantum dot (340 nm long, 50 nm wide). We monitor\ncharge transitions of the elongated quantum dot by measuring radiofrequency\nsingle-electron currents to a reservoir to which we connect a lumped-element\nresonator. We operate the dot as a single electron box to achieve charge\nsensing of remote quantum dots in each array, separated by a distance of 510\nnm. Simultaneous charge detection on both ends of the elongated dot\ndemonstrates that the charge is well distributed across its nominal length,\nsupported by the simulated quantum-mechanical electron density. Our results\nillustrate how single-electron boxes can be realised with versatile foot-\nprints that may enable novel and compact quantum processor layouts, offering\ndistributed charge sensing in addition to the possibility of mediated coupling."
    },
    {
        "anchor": "Antiferromagnetic magnons on a M\u00f6bius strip: topology-induced symmetry\n  breaking: We study a M\\\"obius strip comprising of two antiferromagnetically coupled\nspin chains. To satisfy the boundary condition, magnon excitations feature\nlinear polarization of the N\\'eel vector devoid of chirality, forming two\nnon-degenerate branches of modes that can neither be smoothly connected to nor\nbe decomposed by the circularly-polarized magnons of opposite chirality\ncommonly found in antiferromagnets. Only one branch supports standing-wave\nformation on the M\\\"obius strip while the other does not, owing to its spectral\nshift incurred by the boundary condition. Our findings unravel the profound\nimpact of topology-induced symmetry breaking on magnons.",
        "positive": "Signatures of Weyl semimetals in quasiparticle interference: Impurities act as in situ probes of nontrivial electronic structure, causing\nreal-space modulations in the density of states detected by scanning tunneling\nspectroscopy on the sample surface. We show that distinctive topological\nfeatures of Weyl semimetals can be revealed in the Fourier transform of this\nmap, interpreted in terms of quasiparticle interference (QPI). We develop an\nexact Green's function formalism and apply it to generalized models of Weyl\nsemimetals with an explicit surface. The type of perturbation lifting the Dirac\nnode degeneracy to produce the three-dimensional bulk Weyl phase determines the\nspecific QPI signatures appearing on the surface. QPI Fermi arcs may or may not\nappear, depending on the relative surface orientation and quantum interference\neffects. Line nodes give rise to tube projections of width controlled by the\nbias voltage. We consider the effect of crystal warping, distinguishing\ndispersive arclike features from true Fermi arcs. Finally, we demonstrate that\nthe commonly used joint-density-of-states approach fails qualitatively, and\ncannot describe QPI extinction."
    },
    {
        "anchor": "Spin dynamics and relaxation in the classical-spin Kondo-impurity model\n  beyond the Landau-Lifschitz-Gilbert equation: The real-time dynamics of a classical spin in an external magnetic field and\nlocally exchange coupled to an extended one-dimensional system of\nnon-interacting conduction electrons is studied numerically. Retardation\neffects in the coupled electron-spin dynamics are shown to be the source for\nthe relaxation of the spin in the magnetic field. Total energy and spin is\nconserved in the non-adiabatic process. Approaching the new local ground state\nis therefore accompanied by the emission of dispersive wave packets of\nexcitations carrying energy and spin and propagating through the lattice with\nFermi velocity. While the spin dynamics in the regime of strong exchange\ncoupling J is rather complex and governed by an emergent new time scale, the\nmotion of the spin for weak J is regular and qualitatively well described by\nthe Landau-Lifschitz-Gilbert (LLG) equation. Quantitatively, however, the full\nquantum-classical hybrid dynamics differs from the LLG approach. This is\nunderstood as a breakdown of weak-coupling perturbation theory in J in the\ncourse of time. Furthermore, it is shown that the concept of the Gilbert\ndamping parameter is ill-defined for the case of a one-dimensional system.",
        "positive": "An ion-implanted silicon single-electron transistor: We report on the fabrication and electrical characterization at millikelvin\ntemperatures of a novel silicon single-electron transistor (Si-SET). The island\nand source-drain leads of the Si-SET are formed by the implantation of\nphosphorus ions to a density above the metal-insulator-transition, with the\ntunnel junctions created by undoped regions. Surface gates above each of the\ntunnel junctions independently control the tunnel coupling between the Si-SET\nisland and leads. The device shows periodic Coulomb blockade with a charging\nenergy e$^2$/2C$_\\Sigma$ $\\sim$ 250 $\\mu$eV, and demonstrates a reproducible\nand controllable pathway to a silicon-based SET using CMOS processing\ntechniques."
    },
    {
        "anchor": "Spin-dependent dipole excitation in alkali-metal nanoparticles: We study the spin-dependent electronic excitations in alkali-metal\nnanoparticles. Using numerical and analytical approaches, we focus on the\nresonances in the response to spin-dependent dipole fields. In the spin-dipole\nabsorption spectrum for closed-shell systems, we investigate in detail the\nlowest-energy excitation, the \"surface paramagnon\" predicted by L. Serra et al.\n[Phys. Rev. A 47, R1601 (1993)]. We estimate its frequency from simple\nassumptions for the dynamical magnetization density. In addition, we\nnumerically determine the dynamical magnetization density for all low-energy\nspin-dipole modes in the spectrum. Those many-body excitations can be traced\nback to particle-hole excitations of the noninteracting system. Thus, we argue\nthat the spin-dipole modes are not of collective nature. In open-shell systems,\nthe spin-dipole response to an electrical dipole field is found to increase\nproportionally with the ground-state spin polarization.",
        "positive": "Raman spectroscopic determination of the length, strength,\n  compressibility, Debye temperature, elasticity, and force constant of the C-C\n  bond in graphene: From the perspective of bond relaxation and vibration, we have reconciled the\nRaman shifts of graphene under the stimuli of the number-of-layer,\nuni-axial-strain, pressure, and temperature in terms of the response of the\nlength and strength of the representative bond of the entire specimen to the\napplied stimuli. Theoretical unification of the measurements clarifies that:\n(i) the opposite trends of Raman shifts due to number-of-layer reduction\nindicate that the G-peak shift is dominated by the vibration of a pair of atoms\nwhile the D- and the 2D-peak shifts involves z-neighbor of a specific atom;\n(ii) the tensile strain-induced phonon softening and phonon-band splitting\narise from the asymmetric response of the C3v bond geometry to the C2v\nuni-axial bond elongation; (iii) the thermal-softening of the phonons\noriginates from bond expansion and weakening; and (iv) the pressure- stiffening\nof the phonons results from bond compression and work hardening. Reproduction\nof the measurements has led to quantitative information about the referential\nfrequencies from which the Raman frequencies shift, the length, energy, force\nconstant, Debye temperature, compressibility, elastic modulus of the C-C bond\nin graphene, which is of instrumental importance to the understanding of the\nunusual behavior of graphene."
    },
    {
        "anchor": "Bipolar spin blockade and coherent state superpositions in a triple\n  quantum dot: Spin qubits based on interacting spins in double quantum dots have been\nsuccessfully demonstrated. Readout of the qubit state involves a conversion of\nspin to charge information, universally achieved by taking advantage of a spin\nblockade phenomenon resulting from Pauli's exclusion principle. The archetypal\nspin blockade transport signature in double quantum dots takes the form of a\nrectified current. Currently more complex spin qubit circuits including triple\nquantum dots are being developed. Here we show both experimentally and\ntheoretically (a) that in a linear triple quantum dot circuit, the spin\nblockade becomes bipolar with current strongly suppressed in both bias\ndirections and (b) that a new quantum coherent mechanism becomes relevant.\nWithin this mechanism charge is transferred non-intuitively via coherent states\nfrom one end of the linear triple dot circuit to the other without involving\nthe centre site. Our results have implications in future complex\nnano-spintronic circuits.",
        "positive": "Zero-bias transport anomaly in metallic nanobridges: Magnetic field\n  dependence and universal conductance fluctuations: We present data of transport measurements through a metallic nanobridge\nexhibiting diffusive electron transport. A logarithmic temperature dependence\nand a zero-bias anomaly in the differential conductance are observed,\nindependent of magnetic field. The data can be described by a single scaling\nlaw. The theory of electron-electron interaction in disordered systems, adapted\nto the case of finite-size systems in non-equilibrium, yields quantitative\nagreement with experiment. Measurements of universal conductance functuations\nsupport the assumptions of the theory about the electronic phase coherence."
    },
    {
        "anchor": "Intrinsic non-adiabatic topological torque in magnetic skyrmions and\n  vortices: We propose that topological spin currents flowing in topologically\nnon-trivial magnetic textures, such as magnetic skyrmions and vortices, produce\nan intrinsic non-adiabatic torque of the form ${\\bf T}_t\\sim [(\\partial_x{\\bf\nm}\\times\\partial_y{\\bf m})\\cdot{\\bf m}]\\partial_y{\\bf m}$. We show that this\ntorque, which is absent in one-dimensional domain walls and/or non-topological\ntextures, is responsible for the enhanced non-adiabaticity parameter observed\nin magnetic vortices compared to one-dimensional textures. The impact of this\ntorque on the motion of magnetic skyrmions is expected to be crucial,\nespecially to determine their robustness against defects and pinning centers.",
        "positive": "Effect of uniaxial strain on the reflectivity of graphene: We evaluate the optical reflectivity for a uniaxially strained graphene\nsingle layer between a SiO2 substrate and air. A tight binding model for the\nband dispersion of graphene is employed. As a function of the strain modulus\nand direction, graphene may traverse one of several electronic topological\ntransitions, characterized by a change of topology of its Fermi line. This\nresults in features in the conductivity within the optical range, which might\nbe observable experimentally."
    },
    {
        "anchor": "Room temperature observation of biexcitons in exfoliated WS2 monolayers: Single layers of WS2 are direct gap semiconductors with high\nphotoluminescence (PL) yield holding great promise for emerging applications in\noptoelectronics. The spatial confinement in a 2D monolayer together with the\nweak dielectric screening lead to huge binding energies for the neutral\nexcitons as well as other excitonic complexes, such as trions and biexcitons\nwhose binding energies scale accordingly. Here, we report on the existence of\nbiexcitons in mechanically exfoliated WS2 flakes from 78 K up to room\ntemperature. Performing temperature and power dependent PL measurements, we\nidentify the biexciton emission channel through the superlinear behavior of the\nintegrated PL intensity as a function of the excitation power density. On the\ncontrary, neutral and charged excitons show a linear to sublinear dependence in\nthe whole temperature range. From the energy difference between the emission\nchannels of the biexciton and neutral exciton, a biexciton binding energy of\n65-70 meV is determined.",
        "positive": "Intrinsic Energy Dissipation in CVD-Grown Graphene Nanoresonators: We utilize classical molecular dynamics to study the the quality (Q)-factors\nof monolayer CVD-grown graphene nanoresonators. In particular, we focus on the\neffects of intrinsic grain boundaries of different orientations, which result\nfrom the CVD growth process, on the Q-factors. For a range of misorientations\norientation angles that are consistent with those seen experimentally in\nCVD-grown graphene, i.e. 0$^{\\circ}$ to $\\sim20^{\\circ}$, we find that the\nQ-factors for graphene with intrinsic grain boundaries are 1-2 orders of\nmagnitude smaller than that of pristine monolayer graphene. We find that the\nQ-factor degradation is strongly influenced by both the symmetry and structure\nof the 5-7 defect pairs that occur at the grain boundary. Because of this, we\nalso demonstrate that find the Q-factors CVD-grown graphene can be\nsignificantly elevated, and approach that of pristine graphene, through\napplication of modest (1%) tensile strain."
    },
    {
        "anchor": "Anomalous Josephson effect in semiconducting nanowires as a signature of\n  the topologically nontrivial phase: We study Josephson junctions made of semiconducting nanowires with Rashba\nspin-orbit coupling, where superconducting correlations are induced by the\nproximity effect. In the presence of a suitably directed magnetic field, the\nsystem displays the anomalous Josephson effect: a nonzero supercurrent in the\nabsence of a phase bias between two superconductors. We show that this\nanomalous current can be increased significantly by tuning the nanowire into\nthe helical regime. In particular, in a short junction, a large anomalous\ncurrent is a signature for topologically nontrivial superconductivity in the\nnanowire.",
        "positive": "Novel Fabrication of Micromechanical Oscillators with Nanoscale\n  Sensitivity at Room Temperature: We report on the design, fabrication, and implementation of ultrasensitive\nmicromechanical oscillators. Our ultrathin single-crystal silicon cantilevers\nwith integrated magnetic structures are the first of their kind: They are\nfabricated using a novel high-yield process in which magnetic film patterning\nand deposition are combined with cantilever fabrication. These novel devices\nhave been developed for use as cantilever magnetometers and as force sensors in\nnuclear magnetic resonance force microscopy (MRFM). These two applications have\nachieved nanometer-scale resolution using the cantilevers described in this\nwork. Current magnetic moment sensitivity achieved for the devices, when used\nas magnetometers, is 10^{-15} J/T at room temperature, which is more than a\n1000 fold improvement in sensitivity, compared to conventional magnetometers.\nCurrent room temperature force sensitivity of MRFM cantilevers is ~10^{-16} N\nin a 1 Hz bandwidth, which is comparable to the room temperature sensitivities\nof similar devices of its type. Finite element modeling was used to improve\ndesign parameters, ensure that the devices meet experimental demands, and\ncorrelate mode shape with observed results. The photolithographic fabrication\nprocess was optimized, yielding an average of ~85% and alignment better than\n1000 nm. Post-fabrication focused-ion-beam milling was used to further pattern\nthe integrated magnetic structures when nanometer scale dimensions were\nrequired."
    },
    {
        "anchor": "Exchange bias training effect in IrMn-layer/ferromagnetic-ribbon\n  heterostructures probed with magnetoimpedance: The exchange-bias training effect in IrMn-layer/ferromagnetic-ribbon\nheterostructure is studied by performing magnetoimpedance (MI) measurements.\nAsymmetric, hysteretic and single peak behavior of the MI response and a shift\nin the MI peak to zero fields accompanied by 52% increase in MI has been\ndetected as the signature of the exchange bias (EB) and training effect (TE),\nrespectively. Also, during the consecutive filed sweep of MI response, both EB\nfield and the degree of asymmetry of MI decrease that is another reason for\nexistence of TE in our sample. The analysis of the magneto-optical Kerr effect\n(MOKE) and MI behavior establish that Hoffmann s model (Phys. Rev. Lett. 93,\n097203 (2004)) is a good description of our experimental data, due to the\nexistence of a strong single cycle TE in our IrMn-layer/ferromagnetic-ribbon\nsystem.",
        "positive": "Hall viscosity from elastic gauge fields in Dirac crystals: The combination of Dirac physics and elasticity has been explored at length\nin graphene where the so--called \"elastic gauge fields\" have given rise to an\nentire new field of research and applications: Straintronics. The fact that\nthese elastic fields couple to fermions as the electromagnetic field, implies\nthat many electromagnetic responses will have elastic counterparts not explored\nbefore. In this work we will first show that the presence of elastic gauge\nfields will be the rule rather than the exception in most of the topologically\nnon--trivial materials in two and three dimensions. In particular we will\nextract the elastic gauge fields associated to the recently observed Weyl\nsemimetals, the \"three dimensional graphene\". As it is known, quantum\nelectrodynamics suffers from the chiral anomaly whose consequences have been\nrecently explored in matter systems. We will show that, associated to the\nphysics of the anomalies, and as a counterpart of the Hall conductivity,\nelastic materials will have a Hall viscosity in two and three dimensions with a\ncoefficient orders of magnitude bigger than the previously studied response.\nThe magnitude and generality of the new effect will greatly improve the chances\nfor the experimental observation of this topological, non dissipative response."
    },
    {
        "anchor": "Dynamics of coupled vortices in a pair of ferromagnetic disks: We here experimentally demonstrate that coupled gyration modes can be\nresonantly excited primarily by the ac current in a pair of ferromagnetic disks\nwith varied separating distance. The sole gyrotropic mode clearly splits into a\nhigher and a lower frequency modes for different configurations of polarities\nvia dipolar interaction. These experimental results indicate that the\nmagnetostatically coupled pair of vortices behaves similar to a diatomic\nmolecule with bonding and anti-bonding states. These findings lead to the\npossible extension of designing the magnonic band structure in a chain or an\narray of vortices.",
        "positive": "Thickness tunable quantum interference between surface phonon and Dirac\n  plasmon states in thin-films of the topological insulator Bi2Se3: We report on a >100-fold enhancement of Raman responses from Bi2Se3 thin\nfilms if laser photon energy switches from 2.33 eV (532 nm) to 1.58 eV (785\nnm), which is due to direct optical coupling to Dirac surface states (SS) at\nthe resonance energy of ~1.5 eV (a thickness-independent enhancement) and due\nto nonlinearly excited Dirac plasmon (a thickness-dependent enhancement). Owing\nto the direct optical coupling, we observed an in-plane phonon mode of\nhexagonally arranged Se-atoms associated with a continuous network of Dirac SS.\nThis mode revealed a Fano lineshape for films <15 nm thick, resulting from\nquantum interference between surface phonon and Dirac plasmon states."
    },
    {
        "anchor": "Spin-Incoherent Transport in Quantum Wires: When a quantum wire is weakly confined, a conductance plateau appears at\ne^2/h with decreasing carrier density in zero magnetic field accompanied by a\ngradual suppression of the 2e^2/h plateau. Applying an in-plane magnetic field\nB|| does not alter the value of this quantization; however, the e^2/h plateau\nweakens with increasing B|| up to 9 T, and then strengthens on further\nincreasing B||, which also restores the 2e^2/h plateau. Our results are\nconsistent with spin-incoherent transport in a one-dimensional wire.",
        "positive": "Effective spin theories for edge magnetism in graphene zigzag ribbons: We report a thorough study of the reducibility of edge correlation effects in\ngraphene to much-simplified effective models for the edge states. The latter\nhave been used before in specially tailored geometries. By a systematic\ninvestigation of corrections due to the bulk states in second order\nperturbation theory, we show that the reduction to pure edge state models is\nwell-justified in general geometries. The framework of reduced models discussed\nhere enables the study of non-mean-field correlation physics for system sizes\nfar beyond the reach of conventional methods, such as, e.g., quantum\nMonte-Carlo."
    },
    {
        "anchor": "Noncollinear antiferromagnetic textures driven high harmonic generation\n  from magnetic dynamics in the absence of spin-orbit coupling: We demonstrate the generation of high order harmonics in carrier pumping from\nprecessing ferromagnetic or antiferromagnetic orders, excited via magnetic\nresonance, in the presence of topological antiferromagnetic textures. This\nresults in an enhancement of the carrier dynamics by orders of magnitude.\nInterestingly, the generation process occurs in an intrinsic manner, and is\nsolely governed by the interplay between the s-d exchange coupling underlying\nthe noncollinear antiferromagnetic order and the dynamical s-d exchange\nparameter of the magnetic drive. Therefore, the relativistic spin-orbit\ninteraction is not required for the emergence of high harmonics in the pumped\ncurrents. Accordingly, the noncollinear topological antiferromagnetic order is\npresented as an alternative to spin-orbit interaction for the purpose of\nharnessing high harmonic emission in carrier pumping. Our proposal initiates a\ntantalizing perspective for the exploitation of topological magnetic textures\nin the context of the highly active domain of ultrafast spintronics.",
        "positive": "Magnetic field effects on edge and bulk states in topological insulators\n  based on HgTe/CdHgTe quantum wells with strong natural interface inversion\n  asymmetry: We present a theory of the electron structure and the Zeeman effect for the\nhelical edge states emerging in two-dimensional topological insulators based on\nHgTe/HgCdTe quantum wells with strong natural interface inversion asymmetry.\nThe interface inversion asymmetry, reflecting the real atomistic structure of\nthe quantum well, drastically modifies both bulk and edge states. For the\nin-plane magnetic field, this asymmetry leads to a strong anisotropy of the\nedge-state effective $g$-factor which becomes dependent on the edge\norientation. The interface inversion asymmetry also couples the counter\npropagating edge states in the out-of-plane magnetic field leading to the\nopening of the gap in the edge-state spectrum by arbitrary small fields."
    },
    {
        "anchor": "Higher-order topological pumping and its observation in photonic\n  lattices: The discovery of the quantization of particle transport in adiabatic pumping\ncycles of periodic structures by Thouless [Phys. Rev. B 27, 6083 (1983)] linked\nthe Chern number, a topological invariant characterizing the quantum Hall\neffect in two-dimensional electron gases, with the topology of dynamical\nperiodic systems in one dimension. Here, we demonstrate its counterpart for\nhigher-order topology. Specifically, we show that adiabatic cycles in\ntwo-dimensional crystals with vanishing dipole moments (and therefore zero\noverall particle transport) can nevertheless be topologically nontrivial. These\ncycles are associated with higher-order topology and can be diagnosed by their\nability to produce corner-to-corner transport in certain metamaterial\nplatforms. We experimentally verify the corner to corner transport associated\nwith this topological pump by using an array of photonic waveguides\nadiabatically modulated in their separations and refractive indices. By mapping\nthe dynamical phenomenon demonstrated here from two spatial and one temporal\ndimensions to three spatial dimensions, our observations are equivalent to the\nobservation of chiral hinge states in a three-dimensional second-order\ntopological insulator.",
        "positive": "Local-energy density functionals for an N-dimensional electronic system\n  in a magnetic field: We present a general approach for the construction of the exact\nlocal-energy-density functionals for a uniform N-dimensional electronic system\nin a magnetic field. For arbitrary dimension, we obtain explicit expressions\nfor the matter, kinetic, and exchange density functionals. In the zero-field\nlimit, we recover the usual N-dimensional Thomas-Fermi theory. As an\napplication of our results, we develop a current-density-functional theory, in\nthe spirit of the Thomas-Fermi-Dirac approximation, for an inhomogeneous\nmany-electron system in a magnetic field."
    },
    {
        "anchor": "Local densities, distribution functions, and wave function correlations\n  for spatially resolved shot noise at nanocontacts: We consider a current-carrying, phase-coherent multi-probe conductor to which\na small tunneling contact is attached. We treat the conductor and the tunneling\ncontact as a phase-coherent entity and use a Green's function formulation of\nthe scattering approach. We show that the average current and the current\nfluctuations at the tunneling contact are determined by an effective local\nnon-equilibrium distribution function. This function characterizes the\ndistribution of charge-carriers (or quasi-particles) inside the conductor. It\nis an exact quantum-mechanical expression and contains the phase-coherence of\nthe particles via local partial densities of states, called injectivities. The\ndistribution function is analyzed for different systems in the zero-temperature\nlimit as well as at finite temperature. Furthermore, we investigate in detail\nthe correlations of the currents measured at two different contacts of a\nfour-probe sample, where two of the probes are only weakly coupled contacts. In\nparticular, we show that the correlations of the currents are at\nzero-temperature given by spatially non-diagonal injectivities and\nemissivities. These non-diagonal densities are sensitive to correlations of\nwave functions and the phase of the wave functions. We consider ballistic\nconductors and metallic diffusive conductors. We also analyze the Aharonov-Bohm\noscillations in the shot noise correlations of a conductor which in the absence\nof the nano-contacts exhibits no flux-sensitivity in the conductance.",
        "positive": "Detection of adsorbed transition-metal porphyrins by spin-dependent\n  conductance of graphene nanoribbon: Electronic transport in a zig-zag-edge graphene nanoribbon (GNR) and its\nmodification by adsorbed transition metal porphyrins is studied by means of\ndensity functional theory calculations. The detachment reaction of the metal\ncentre of the porphyrin is investigated both in the gas phase and for molecules\nadsorbed on the GNR. As most metal porphyrins are very stable against this\nreaction, it is found that these molecules bind only weakly to a perfect\nnanoribbon. However, interaction with a single-atom vacancy in the GNR results\nin chemical bonding by the transition metal centre being shared between\nnitrogen atoms in the porphyrin ring and the carbon atoms next to the vacancy\nin the GNR. For both the physisorbed and the chemisorbed geometry, the\ninclusion of van der Waals interaction results in a significant enlargement of\nthe binding energy and reduction of the adsorption height. Electronic transport\ncalculations using non-equilibrium Greens functions show that the conductivity\nof the GNR is altered by the chemisorbed porphyrin molecules. Since the metal\ncenters of porphyrins carry an element-specific magnetic moment, not only the\nnet conductance, but also the spin-dependent conductance of the GNR is\naffected. In particular, the adsorption of Ru-porphyrin on the single-atom\nvacancy results in a very large spin polarization of the current of 88% at\nsmall applied source-drain voltages. Based on our results, we suggest that a\nspin valve constructed from a GNR with ferromagnetic contacts could be used as\na sensitive detector that could discriminate between various metal porphyrins."
    },
    {
        "anchor": "Suppression of single-molecule conductance fluctuations using extended\n  anchor groups on graphene and carbon-nanotube electrodes: Devices formed from single molecules attached to noble-metal electrodes\nexhibit large conductance fluctuations, which inhibit their development as\nreproducible functional units. We demonstrate that single molecules with planar\nanchor groups attached to carbon-based electrodes are more resilient to\natomic-scale variation in the contacts and exhibit significantly lower\nconductance fluctuations. We examine the conductance of a 2,6-dibenzylamino\ncore-substituted naphthalenediimide chromophore attached to carbon electrodes\nby either phenanthrene anchors or more extended anchor groups, which include\noligophenylene ethynylene spacers. We demonstrate that for the more spatially\nextended anchor groups conductance fluctuations are significantly reduced. The\ncurrent-voltage characteristic arising from long-range tunneling is found to be\nstrongly nonlinear with pronounced conductance suppression below a threshold\nvoltage of approximately 2.5 V.",
        "positive": "Formation of the stopped polarization pulse in a rectangular quantum\n  well: The induced polarization oscillations in a one-dimensional rectangular\nquantum well are modeled by a numerical solution of the time-dependent\nSchroedinger equation. The finite-difference discretization over time is\nrealized in the framework of the Crank-Nicolson algorithm, whereas over the\nspatial coordinate it is combined with the exterior complex-scaling technique.\nA formation of the harmonic oscillations of the dipole moment by an incident\nshort unipolar pulse is shown. It is obtained that the frequency of\noscillations is solely defined by the energy of the main resonant transition.\nMoreover, if two such short unipolar pulses are delayed by a half-period of the\noscillation, then these oscillations can be abruptly induced and stopped. Thus,\nthe so-called stopped polarization pulse is obtained. It is shown that both the\namplitude and the duration of the incident unipolar pulse, contributing to the\nso-called electric pulse area, define the impact of the incident pulse on the\nquantum system."
    },
    {
        "anchor": "Aharonov-Bohm effect in a helical ring with long-range hopping: Effects\n  of Rashba spin-orbit interaction and disorder: We study Aharonov-Bohm effect in a two-terminal helical ring with long-range\nhopping in presence of Rashba spin-orbit interaction. We explore how the spin\npolarization behavior changes depending on the applied magnetic flux and the\nincoming electron energy. The most interesting feature that we articulate in\nthis system is that zero-energy crossings appear in the energy spectra at\n$\\Phi=0$ and also at integer multiples of half-flux quantum values ($n\n\\Phi_0/2$, $n$ being an integer) of the applied magnetic flux. We investigate\nthe transport properties of the ring using Green's function formalism and find\nthat the zero energy transmission peaks corresponding to those zero energy\ncrossings vanish in presence of Rashba spin-orbit interaction. We also\nincorporate static random disorder in our system and show that the zero energy\ncrossings and transmission peaks are not immune to disorder even in absence of\nRashba spin-orbit interaction. The latter prevents the possibility of behaving\nthese helical states in the ring like topological insulator edge states.",
        "positive": "Engineering the in-plane anomalous Hall effect in Cd$_3$As$_2$ thin\n  films: We predict two topological phase transitions for cadmium arsenide\n(\\ce{Cd3As2}) thin films under in-plane magnetic field, taking advantage of a\nfour-band $k\\cdot p$ model and effective $g$ factors calculated from first\nprinciples. Film thickness, growth direction and in-plane Zeeman coupling\nstrength can all serve as control parameters to drive these phase transitions.\nFor (001) oriented \\ce{Cd3As2} thin films, a two dimensional Weyl semimetal\nphase protected by $C_{2z}\\mathcal{T}$ symmetry can be realized using an\nin-plane magnetic field, which has recently been reported in our companion\npaper. We then put forth two pathways to achieve in-plane anomalous Hall\neffects (IPAHE). By either introducing a trigonal warping term or altering the\ngrowth orientation, the emergent $C_{2z} \\mathcal{T}$ symmetry can be broken.\nConsequently, in the clean limit and at low temperatures, quantized Hall\nplateaus induced by in-plane Zeeman fields become observable."
    },
    {
        "anchor": "Current-Driven Domain Wall Motion: Velocity, Current and Phase\n  Transition: The relation between domain wall motion and intensity of driven current is\nexamined in a phenomenological theory where the kinetic energy is expanded as a\nseries of polynomial function of current density just as the Landau phase\ntransition theory. The dependency of velocity on current density is root square\nwhich degenerates into linear if the current is much higher than the critical\nvalue. The theory result is consistent with several previous experiments and\nalso can explain the change of critical current in the presence of temperature.\nThe role of temperature plays in the dynamics of domain wall motion is also\ndiscussed. The phase transition theory in terms of current density is employed\nto explain the critical behavior of domain wall motion.",
        "positive": "Molecular formations and spectra due to electron correlations in\n  three-electron hybrid double-well qubits: We show that systematic full configuration-interaction (FCI) calculations\nenable prediction of the energy spectra and the intrinsic spatial and spin\nstructures of the many-body wave functions as a function of the detuning\nparameter for the case of three-electron hybrid qubits based on GaAs asymmetric\ndouble quantum dots. Specifically, in comparison with the case of weak\ninteractions and treating the entire three-electron double-dot hybrid qubit as\nan integral unit, it is shown that the predicted spectroscopic patterns,\noriginating from strong electron correlations, manifest the formation of Wigner\nmolecules (WMs). Signatures of WM formation include: (1) a strong suppression\nof the energy gaps relative to the non-interacting-electrons modeling, and (2)\nthe appearance of a pair of avoided crossings arising between states associated\nwith two-electron occupancies in the left and right wells. The Wigner molecule\nis a physical entity associated with electron localization within each well and\nit cannot be captured by the previously employed independent-particle or\ntwo-site-Hubbard theoretical modeling of the hybrid qubits. The emergence of\nstrong WMs is investigated in depth through the concerted use of FCI-adapted\ndiagnostic tools like charge and spin densities, as well as conditional\nprobability distributions. Furthermore, the energy spectrum as a function of\nthe strength of the Coulomb repulsion (at constant detuning) is calculated in\norder to complement the thorough analysis of the factors contributing to WM\nemergence. We report remarkable agreement with recent experimental\nmeasurements. The present FCI methodology for multi-well quantum dots can be\nstraightforwardly extended to treat valleytronic two-band Si/SiGe hybrid\nqubits, where the central role of the WMs was confirmed recently."
    },
    {
        "anchor": "Electric-field controlled spin reversal in a quantum dot with\n  ferromagnetic contacts: Manipulation of the spin-states of a quantum dot by purely electrical means\nis a highly desirable property of fundamental importance for the development of\nspintronic devices such as spin-filters, spin-transistors and single-spin\nmemory as well as for solid-state qubits. An electrically gated quantum dot in\nthe Coulomb blockade regime can be tuned to hold a single unpaired spin-1/2,\nwhich is routinely spin-polarized by an applied magnetic field. Using\nferromagnetic electrodes, however, the properties of the quantum dot become\ndirectly spin-dependent and it has been demonstrated that the ferromagnetic\nelectrodes induce a local exchange-field which polarizes the localized spin in\nthe absence of any external fields. Here we report on the experimental\nrealization of this tunneling-induced spin-splitting in a carbon nanotube\nquantum dot coupled to ferromagnetic nickel-electrodes. We study the\nintermediate coupling regime in which single-electron states remain well\ndefined, but with sufficiently good tunnel-contacts to give rise to a sizable\nexchange-field. Since charge transport in this regime is dominated by the\nKondo-effect, we can utilize this sharp many-body resonance to read off the\nlocal spin-polarization from the measured bias-spectroscopy. We show that the\nexchange-field can be compensated by an external magnetic field, thus restoring\na zero-bias Kondo-resonance, and we demonstrate that the exchange-field itself,\nand hence the local spin-polarization, can be tuned and reversed merely by\ntuning the gate-voltage. This demonstrates a very direct electrical control\nover the spin-state of a quantum dot which, in contrast to an applied magnetic\nfield, allows for rapid spin-reversal with a very localized addressing.",
        "positive": "Dynamically Induced Topology and Quantum Monodromies in a Proximity\n  Quenched Gapless Wire: We study the quench dynamics of a topologically trivial one-dimensional\ngapless wire following its sudden coupling to topological bound states. We find\nthat as the bound states leak into and propagate through the wire, signatures\nof their topological nature survive and remain measurable over a long lifetime.\nThus, the quench dynamically induces topological properties in the gapless\nwire. Specifically, we study a gapless wire coupled to fractionally charged\nsolitons or Majorana fermions and characterize the dynamically induced topology\nin the wire, in the presence of disorder and short-range interactions, by\nanalytical and numerical calculations of the dynamics of fractional charge,\nfermion parity, entanglement entropy, and fractional exchange statistics. In a\ndual effective description, this phenomenon is described by correlators of\nboundary changing operators, which, remarkably, generate topologically\nnon-trivial monodromies in the gapless wire, both for abelian and non-abelian\nquantum statistics of the bound states."
    },
    {
        "anchor": "Pseudo-gauge Fields in Dirac and Weyl Materials: Electrons in low-temperature solids are governed by the non-relativistic\nSchr$\\ddot{o}$dinger equation, since the electron velocities are much slower\nthan the speed of light. Remarkably, the low-energy quasi-particles given by\nelectrons in various materials can behave as relativistic Dirac/Weyl fermions\nthat obey the relativistic Dirac/Weyl equation. These materials are called\n\"Dirac/Weyl materials\", which provide a tunable platform to test relativistic\nquantum phenomena in table-top experiments. More interestingly, different types\nof physical fields in these Weyl/Dirac materials, such as magnetic\nfluctuations, lattice vibration, strain, and material inhomogeneity, can couple\nto the \"relativistic\" quasi-particles in a similar way as the $U(1)$ gauge\ncoupling. As these fields do not have gauge-invariant dynamics in general, we\nrefer to them as \"pseudo-gauge fields\". In this chapter, we overview the\nconcept and the physical consequences of pseudo-gauge fields in Weyl/Dirac\nmaterials. In particular, we will demonstrate that pseudo-gauge fields can\nprovide a unified understanding of a variety of physical phenomena, including\nchiral zero modes inside a magnetic vortex core of magnetic Weyl semimetals, a\ngiant current response at magnetic resonance in magnetic topological\ninsulators, and piezo-electromagnetic response in time-reversal invariant\nsystems. These phenomena are deeply related to various concepts in high-energy\nphysics, such as chiral anomaly and axion electrodynamics.",
        "positive": "Interference and parity blockade in transport through a Majorana box: A Majorana box - two topological superconducting nanowires coupled via a\ntrivial superconductor - is a building block in devices aiming to demonstrate\nnonabelian physics, as well as for topological quantum computer architectures.\nWe theoretically investigate charge transport through a Majorana box and show\nthat current can be blocked when two Majoranas couple to the same lead, fixing\ntheir parity. In direct analogy to Pauli spin blockade in spin qubits, this\nparity blockade can be used for fast and high-fidelity qubit initialization and\nreadout, as well as for current-based measurements of decoherence times.\nFurthermore, we demonstrate that transport can distinguish between a clean\nMajorana box and a disordered box with additional unwanted Majorana or Andreev\nbound states."
    },
    {
        "anchor": "Charge Transport in Disordered Graphene-Based Low Dimensional Materials: Two-dimensional graphene, carbon nanotubes and graphene nanoribbons represent\na novel class of low dimensional materials that could serve as building blocks\nfor future carbon-based nanoelectronics. Although these systems share a similar\nunderlying electronic structure, whose exact details depend on confinement\neffects, crucial differences emerge when disorder comes into play. In this\nshort review, we consider the transport properties of these materials, with\nparticular emphasis to the case of graphene nanoribbons. After summarizing the\nelectronic and transport properties of defect-free systems, we focus on the\neffects of a model disorder potential (Anderson-type), and illustrate how\ntransport properties are sensitive to the underlying symmetry. We provide\nanalytical expressions for the elastic mean free path of carbon nanotubes and\ngraphene nanoribbons, and discuss the onset of weak and strong localization\nregimes, which are genuinely dependent on the transport dimensionality. We also\nconsider the effects of edge disorder and roughness for graphene nanoribbons in\nrelation to their armchair or zigzag orientation.",
        "positive": "Enhanced Delayed Fluorescence in Tetracene Crystals by Strong\n  Light-Matter Coupling: We demonstrate experimentally an enhanced delayed fluorescence in tetracene\nsingle crystals strongly coupled to optical modes in open cavities formed by\narrays of plasmonic nanoparticles. Hybridization of singlet excitons with\ncollective plasmonic resonances in the arrays leads to the splitting of the\nmaterial dispersion into a lower and an upper polariton band. This splitting\nsignificantly modifies the dynamics of the photo-excited tetracene crystal,\nresulting in an increase of the delayed fluorescence by a factor of four. The\nenhanced delayed fluorescence is attributed to the emergence of an additional\nradiative decay channel, where the lower polariton band harvests long-lived\ntriplet states. There is also an increase in total emission, which is\nwavelength dependent, and can be explained by the direct emission from the\nlower polariton band, the more effcient light out-coupling and the enhancement\nof the excitation intensity. The observed enhanced fluorescence opens the\npossibility of effcient radiative triplet harvesting in open optical cavities,\nto improve the performance of organic light emitting diodes."
    },
    {
        "anchor": "Spin-current quantization in a quantum point contact with spin-orbit\n  interaction: We develop a realistic and analytically tractable model to describe the spin\ncurrent which arises in a quantum point contact (QPC) with spin-orbit\ninteraction (SOI) upon a small voltage is applied. In the model, the QPC is\nconsidered as a saddle point of two-dimensional potential landscape. The SOI\nacts within a finite region and is absent deep in the reservoirs. The SOI\nstrength is not supposed to be strong. It is shown that the spin polarization\nappears in the third order of the perturbation theory as a result of definite\ncombinations of electron transitions. They include two intersubband transitions\nto nearest subbands and one intrasubband transition. The spin current is\nproportional to the cube of the SOI strength and strongly depends on geometric\nparameters of the saddle point. The spin is polarized in the plane of the QPC\nand directed normally to the electron current if the SOI is of Rashba type. As\na function of the saddle-point potential (i.e., the height of the QPC barrier),\nthe spin conductance and especially the spin polarization have characteristic\nfeatures (specifically, peaks) correlated with the charge conductance\nquantization steps. The peak shape depends on the length of the region where\nthe SOI acts. In QPCs with sharp potential landscape, this picture is distorted\nby interference processes.",
        "positive": "Theory of vortex states in magnetic nanodisks with induced\n  Dzyaloshinskii-Moriya interactions: Vortex states in magnetic nanodisks are essentially affected by\nsurface/interface induced Dzyaloshinskii-Moriya interactions. Within a\nmicromagnetic approach we calculate the equilibrium sizes and shape of the\nvortices as functions of magnetic field, the material and geometrical\nparameters of nanodisks. It was found that the Dzyaloshinskii-Moriya coupling\ncan considerably increase sizes of vortices with \"right\" chirality and suppress\nvortices with opposite chirality. This allows to form a bistable system of\nhomochiral vortices as a basic element for storage applications."
    },
    {
        "anchor": "Decreasing excitation gap in Andreev billiards by disorder scattering: We investigate the distribution of the lowest-lying energy states in a\ndisordered Andreev billiard by solving the Bogoliubov-de Gennes equation\nnumerically. Contrary to conventional predictions we find a decrease rather\nthan an increase of the excitation gap relative to its clean ballistic limit.\nWe relate this finding to the eigenvalue spectrum of the Wigner-Smith time\ndelay matrix between successive Andreev reflections. We show that the longest\nrather than the mean time delay determines the size of the excitation gap. With\nincreasing disorder strength the values of the longest delay times increase,\nthereby, in turn, reducing the excitation gap.",
        "positive": "Rediscovering Black Phosphorus: A Unique Anisotropic 2D Material for\n  Optoelectronics and Electronics: Anisotropy refers to the property of a material exhibiting directionally\ndependent features. In this paper, we introduce black phosphorous (BP), the\nmost stable allotrope of phosphorus in layered orthorhombic structure with a\nbandgap of 0.3 eV in bulk, as a unique 2D material in which electrons, phonons\nand their interactions with photons behave in a highly anisotropic manner\nwithin the plane of the layers. The unique anisotropic nature of BP thin films\nis revealed using angle-resolved Raman and infrared spectroscopies, together\nwith angle-resolved transport study. For 15 nm thick BP, we measure Hall\nmobility of 1000 and 600 cm^2/Vs for holes along the light (x) and heavy (y)\neffective mass directions, respectively, at 120 K. These BP thin films also\nexhibit large and anisotropic in-plane optical conductivity from 2 to 5\nmicrometer wavelength. Field effect transistors using 4 to 30 layers of BP (2\nto 15 nm) as channel material exhibit an on-off current ratio exceeding 10^5, a\nfield-effect mobility of 205 cm^2/Vs, and good saturation properties all at\nroom temperature, suggesting its promising future in high performance thin film\nelectronics. By introducing narrow bandgap BP into the 2D material family, we\nfill the space between semi-metallic graphene and large bandgap TMDCs, where\ngreat potentials for infrared optoelectronics lie. Most importantly, the unique\nanisotropic nature of this intriguing material creates unprecedented\npossibilities for the realization of conceptually new optoelectronic and\nelectronic devices in which angle-dependent physical properties are highly\ndesirable."
    },
    {
        "anchor": "Impact of nanostructure configuration on the photovoltaic performance of\n  quantum dot arrays: In this work, a mesoscopic model based on the non-equilibrium Green's\nfunction formalism for a tight-binding-like effective Hamiltonian is used to\ninvestigate a selectively contacted quantum dot array designed for operation as\na single junction quantum dot solar cell. By establishing a direct relation\nbetween nanostructure configuration and optoelectronic properties, the\ninvestigation reveals the influence of inter-dot and dot-contact coupling\nstrengths on the rates of charge carrier photogeneration, radiative\nrecombination, and extraction at contacts, and consequently on the ultimate\nperformance of photovoltaic devices with finite quantum dot arrays as the\nactive medium. For long carrier lifetimes, the dominant configuration effects\noriginate in the dependence of the joint density of states on the inter-dot\ncoupling in terms of band width and effective band gap. In the low carrier\nlifetime regime, where recombination competes with carrier extraction, the\nextraction efficiency shows a critical dependence on the dot-contact coupling.",
        "positive": "Transport Spectroscopy of Single Phosphorus Donors in a Silicon\n  Nanoscale Transistor: We have developed nano-scale double-gated field-effect-transistors for the\nstudy of electron states and transport properties of single\ndeliberately-implanted phosphorus donors. The devices provide a high-level of\ncontrol of key parameters required for potential applications in\nnanoelectronics. For the donors, we resolve transitions corresponding to two\ncharge states successively occupied by spin down and spin up electrons. The\ncharging energies and the Lande g-factors are consistent with expectations for\ndonors in gated nanostructures."
    },
    {
        "anchor": "Charge transport and electron-hole asymmetry in low-mobility\n  graphene/hexagonal boron nitride heterostructures: Graphene/hexagonal boron nitride (G/$h$-BN) heterostructures offer an\nexcellent platform for developing nanoelectronic devices and for exploring\ncorrelated states in graphene under modulation by a periodic superlattice\npotential. Here, we report on transport measurements of nearly\n$0^{\\circ}$-twisted G/$h$-BN heterostructures. The heterostructures\ninvestigated are prepared by dry transfer and thermally annealing processes and\nare in the low mobility regime (approximately\n$3000~\\mathrm{cm}^{2}\\mathrm{V}^{-1}\\mathrm{s}^{-1}$ at 1.9 K). The replica\nDirac spectra and Hofstadter butterfly spectra are observed on the hole\ntransport side, but not on the electron transport side, of the\nheterostructures. We associate the observed electron-hole asymmetry to the\npresences of a large difference between the opened gaps in the conduction and\nvalence bands and a strong enhancement in the interband contribution to the\nconductivity on the electron transport side in the low-mobility G/$h$-BN\nheterostructures. We also show that the gaps opened at the central Dirac point\nand the hole-branch secondary Dirac point are large, suggesting the presence of\nstrong graphene-substrate interaction and electron-electron interaction in our\nG/$h$-BN heterostructures. Our results provide additional helpful insight into\nthe transport mechanism in G/$h$-BN heterostructures.",
        "positive": "Transient dynamics of a magnetic impurity coupled to superconducting\n  electrodes: exact numerics versus perturbation theory: Impurities coupled to superconductors offer a controlled platform to\nunderstand the interplay between superconductivity, many-body interactions, and\nnon-equilibrium physics. In the equilibrium situation, local interactions at\nthe impurity induce a transition between the spin-singlet to the spin-doublet\nground state, resulting in a supercurrent sign reversal ($0-\\pi$ transition).\nIn this work, we apply the exact time-dependent density matrix renormalization\ngroup method to simulate the transient dynamics of such superconducting\nsystems. We also use a perturbative approximation to analyze their properties\nat longer times. These two methods agree for a wide range of parameters. In a\nphase-biased situation, the system gets trapped in a metastable state\ncharacterized by a lower supercurrent compared to the equilibrium case. We show\nthat local Coulomb interactions do not provide an effective relaxation\nmechanism for the initially trapped quasiparticles. In contrast, other\nrelaxation mechanisms, such as coupling to a third normal lead, make the\nimpurity spin relax for parameter values corresponding to the equilibrium $0$\nphase. For parameters corresponding to the equilibrium $\\pi$ phase the impurity\nconverges to a spin-polarized stationary state. Similar qualitative behavior is\nfound for a voltage-biased junction, which provides an effective relaxation\nmechanism for the trapped quasiparticles in the junction."
    },
    {
        "anchor": "Control of polarization hysteresis temperature behavior by interfacial\n  screening in thin ferroelectric films: Ferroelectric interfaces are unique model objects for fundamental studies of\npolar surface properties such as versatile screening mechanisms of spontaneous\npolarization by free carriers and possible ion exchange with ambient media. The\neffect of ionic adsorption by electrically-open (i.e. non-electroded)\nferroelectric surface on polarization reversal in the ferroelectric had been\ninvestigated experimentally and theoretically, however the effect influence on\nthe temperature behaviour of polarization hysteresis remains unexplored. Also\nthe comparative theoretical analysis of the ferroelectric hysteresis for linear\nand nonlinear electronic screenings, and strongly nonlinear ionic screening of\nthe spontaneous polarization was absent. In this work we study the free energy\nrelief of a thin ferroelectric film covered by a screening charge layer of\ndifferent nature and ultra-thin gap separating the film surface from the top\nelectrode and calculate hysteresis loops of polarization and screening charge\nat different temperatures in the considered system. The dependence of the\nscreening charge density on electric potential was considered for three basic\nmodels, namely for the linear Bardeen-type model of electronic surface states\n(BS), nonlinear Fermi-Dirac (FD) density of states describing two-dimensional\nelectron gas at the film-gap interface, and strongly nonlinear\nStephenson-Highland (SH) model describing the surface charge density of\nabsorbed ions by Langmuir adsorption isotherms. Appeared that BS, FD and SH\nscreening charges, which properties are principally different, determine the\nfree energy relief (including polarization values corresponding to the free\nenergy minima at different applied voltages) and control the shape of\npolarization hysteresis loops at different temperatures.",
        "positive": "Orbital magnetism of coupled bands models: We develop a gauge-independent perturbation theory for the grand potential of\nitinerant electrons in two-dimensional tight-binding models in the presence of\na perpendicular magnetic field. At first order in the field, we recover the\nresult of the so-called {\\it modern theory of orbital magnetization} and, at\nsecond order, deduce a new general formula for the orbital susceptibility. In\nthe special case of two coupled bands, we relate the susceptibility to\ngeometrical quantities such as the Berry curvature. Our results are applied to\nseveral two-band -- either gapless or gapped -- systems. We point out some\nsurprising features in the orbital susceptibility -- such as in-gap\ndiamagnetism or parabolic band edge paramagnetism -- coming from interband\ncoupling. From that we draw general conclusions on the orbital magnetism of\nitinerant electrons in multi-band tight-binding models."
    },
    {
        "anchor": "Transport signatures of a Floquet topological transition at the helical\n  edge: The manipulation of the helical edge states of two-dimensional topological\ninsulators is crucial for the development of technological applications.\nRecently, an important step forward, namely, the experimental realization of a\nquantum point contact between helical edges, has been accomplished. We\ntheoretically predict that such a quantum point contact, in the presence of a\ntime periodic applied electric field, is characterized by a topological quantum\nphase transition in the Floquet spectrum. Moreover, we show that it is possible\nto detect this dynamical topological quantum phase transition by a bare\nconductance measurements.",
        "positive": "Quantum Critical Behavior of Two Coupled Bose-Einstein Condensates: The quantum critical behavior of the Bose-Hubbard model for a description of\ntwo coupled Bose-Einstein condensates is studied within the framework of an\nalgebraic theory. Energy levels, wavefunction overlaps with those of the Rabi\nand Fock regimes, and the entanglement are calculated exactly as functions of\nthe phase parameter and the number of bosons. The results show that the system\ngoes though a phase transition and that the critical behavior is enhanced in\nthe thermodynamic limit."
    },
    {
        "anchor": "Dephasing of electrons in mesoscopic metal wires due to zero-point\n  fluctuations of optically active localized plasmon modes: Optically active localized plasmon modes may be very abundant on a rough\nsurface of a metal wire. Zero-point fluctuations of these modes are shown to\nproduce local DC magnetization. Thus, the effect of these modes on the electron\ndephasing time is similar to the effect of magnetic impurities.",
        "positive": "Non-Adlerian synchronization of dipolar coupled vortex Spin-Torque\n  Nano-Oscillators: We investigate analytically and numerically the synchronization dynamics of\ndipolarly coupled vortex based Spin-Torque Nano Oscillators (STNO) with\ndifferent pillar diameters. We identify the critical interpillar distances on\nwhich synchronization occurs as a function of their diameter mismatch. We\nobtain numerically a phase diagram showing the transition between\nunsynchronized and synchronized states and compare it to analytical predictions\nwe make using Thiele approach. Our study demonstrates that for relatively small\ndiameters differences the synchronization dynamics can be described\nqualitatively using Adler equation. However when the diameters difference\nincreases significantly, the system becomes strongly non-Adlerian."
    },
    {
        "anchor": "An edge index for the Quantum Spin-Hall effect: Quantum Spin-Hall systems are topological insulators displaying\ndissipationless spin currents flowing at the edges of the samples. In\ncontradistinction to the Quantum Hall systems where the charge conductance of\nthe edge modes is quantized, the spin conductance is not and it remained an\nopen problem to find the observable whose edge current is quantized. In this\npaper, we define a particular observable and the edge current corresponding to\nthis observable. We show that this current is quantized and that the\nquantization is given by the index of a certain Fredholm operator. This\nprovides a new topological invariant that is shown to take same values as the\nSpin-Chern number previously introduced in the literature. The result gives an\neffective tool for the investigation of the edge channels' structure in Quantum\nSpin-Hall systems. Based on a reasonable assumption, we also show that the edge\nconducting channels are not destroyed by a random edge.",
        "positive": "Associative memory by virtual oscillator network based on single\n  spin-torque oscillator: A coupled oscillator network may be able to perform an energy-efficient\nassociative memory operation. However, its realization has been difficult\nbecause inhomogeneities unavoidably arise among the oscillators during\nfabrication and lead to an unreliable operation. This issue could be resolved\nif the oscillator network were able to be formed from a single oscillator.\nHere, we performed numerical simulations and theoretical analyses on an\nassociative memory operation that uses a virtual oscillator network based on a\nspin-torque oscillator. The virtual network combines the concept of coupled\noscillators with that of feedforward neural networks. Numerical experiments\ndemonstrate successful associations of $60$-pixel patterns with various\nmemorized patterns. Moreover, the origin of the associative memory is shown to\nbe forced synchronization driven by feedforward input, where phase differences\namong oscillators are fixed and correspond to the colors of the pixels in the\npattern."
    },
    {
        "anchor": "Influence of yttrium iron garnet thickness and heater opacity on the\n  nonlocal transport of electrically and thermally excited magnons: We studied the nonlocal transport behavior of both electrically and thermally\nexcited magnons in yttrium iron garnet (YIG) as a function of its thickness.\nFor electrically injected magnons, the nonlocal signals decrease monotonically\nas the YIG thickness increases. For the nonlocal behavior of the thermally\ngenerated magnons, or the nonlocal spin Seebeck effect (SSE), we observed a\nsign reversal which occurs at a certain heater-detector distance, and it is\ninfluenced by both the opacity of the YIG/heater interface and the YIG\nthickness. Our nonlocal SSE results can be qualitatively explained by the\nbulk-driven SSE mechanism together with the magnon diffusion model. Using a\ntwo-dimensional finite element model (2D-FEM), we estimated the bulk spin\nSeebeck coefficient of YIG at room temperature. The quantitative disagreement\nbetween the experimental and modeled results indicates more complex processes\ngoing on in addition to magnon diffusion and relaxation, especially close to\nthe contacts.",
        "positive": "Spin dephasing and photoinduced spin diffusion in high-mobility\n  110-grown GaAs-AlGaAs two-dimensional electron systems: We have studied spin dephasing and spin diffusion in a high-mobility\ntwo-dimensional electron system, embedded in a GaAs/AlGaAs quantum well grown\nin the [110] direction, by a two-beam Hanle experiment. For very low excitation\ndensity, we observe spin lifetimes of more than 16 ns, which rapidly decrease\nas the pump intensity is increased. Two mechanisms contribute to this decrease:\nthe optical excitation produces holes, which lead to a decay of electron spin\nvia the Bir-Aranov-Pikus mechanism and recombination with spin-polarized\nelectrons. By scanning the distance between the pump and probe beams, we\nobserve the diffusion of spin-polarized electrons over more than 20 microns.\nFor high pump intensity, the spin polarization in a distance of several microns\nfrom the pump beam is larger than at the pump spot, due to the reduced\ninfluence of photogenerated holes."
    },
    {
        "anchor": "Acoustic Edge Magnetoplasmons and Quantum Hall Effect: Discussed in the present study are details of the behavior of low-frequency\n\"acoustic\" ($ac$) modes in the spectrum of edge magnetoplasma oscillations in\naxially symmetric degenerate 2D electron systems where electron density\ndistribution $n(\\vec r)$ behaves as $n(\\vec r \\to R)\\to 0$ when $r$ approaches\nthe external radius $R$ of the domain occupied by electrons. It is shown that\nfinding the dependence of the spectrum of $ac$-modes on radial ($l$) and\nazimuthal ($m$) indices when both $l$ and $m$ are small requires axially\nsymmetric solution of the relevant problem. The desires is achieved in the\nso-called elliptic approximation for electron density distribution $n(\\vec r)$.\nThe obtained results are employed to interpret available data on the excitation\nof $ac$-modes in degenerate electron disks with smooth electron density profile\nplaced in the magnetic field $H$ normal to the disk plane. The performed\nanalysis confirms reported detection of the soft $ac$-mode in the range of $H\n\\gg H_{max}$ where $H_{max}$ is the field at which the maximum of the\n$\\omega_{lm}^{s}(H)$ curve is observed (here and below $\\omega_{lm}^{s}(H)$\nstands for the frequency of the soft $ac$-mode).\n  A strong interaction of the $ac$-modes with $(integer)$-channels inevitably\narising near the boundaries of 2D electron systems with smooth electron density\nprofile as the magnetic field is varied in the Quantum Hall Effect (QHE) regime\nis emphasized. Well-formed $integer$-stripes can suppress some acoustic modes\nwhich is actually observed in experiments.",
        "positive": "Microwave Absorption of Surface-State Electrons on Liquid $^3$He: We have investigated the intersubband transitions of surface state electrons\n(SSE) on liquid $^3$He induced by microwave radiation at temperatures from 1.1\nK down to 0.01 K. Above 0.4 K, the transition linewidth is proportional to the\ndensity of $^3$He vapor atoms. This proportionality is explained well by Ando's\ntheory, in which the linewidth is determined by the electron - vapor atom\nscattering. However, the linewidth is larger than the calculation by a factor\nof 2.1. This discrepancy strongly suggests that the theory underestimates the\nelectron - vapor atom scattering rate. At lower temperatures, the absorption\nspectrum splits into several peaks. The multiple peak structure is partly\nattributed to the spatial inhomogeneity of the static holding electric field\nperpendicular to the electron sheet."
    },
    {
        "anchor": "Comment on \"Wave-scattering formalism for thermal conductance in thin\n  wires with surface disorder\": In their calculations based on the Landauer transport equation, Akguc and\nGong [Phys. Rev. B 80, 195408 (2009)] obtained an expression for the heat\nconductance of a quantum wire valid in the ballistic regime and in the limit of\nvanishing temperature difference between reservoirs. Their result appears to be\ndifferent from the one reported in the previous paper of Rego and Kirczenow\n[Phys. Rev. Lett. 81, 232 (1998)], which led them to argue that their new\nresult was the correct one. We show here that, in fact, both results are\ncorrect since different definitions for the dilogarithm function were used in\nthose papers. Hence, comparisons between these two results should be done with\ncare.",
        "positive": "Deterministic coupling of site-controlled quantum emitters in monolayer\n  semiconductors to plasmonic nanocavities: Solid-state single-quantum emitters are a crucial resource for on-chip\nphotonic quantum technologies and require efficient cavity-emitter coupling to\nrealize quantum networks beyond the single-node level. Previous approaches to\nenhance light-matter interactions rely on forming nanocavities around randomly\nlocated quantum dots or color centers but lack spatial control of the quantum\nemitter itself that is required for scaling. Here we demonstrate a\ndeterministic approach to achieve Purcell-enhancement at lithographically\ndefined locations using the sharp corner of a metal nanocube for both electric\nfield enhancement and to deform a two-dimensional material. For a 3 by 4 array\nof strain-induced exciton quantum emitters formed into monolayer WSe2 we show\nspontaneous emission rate enhancement with Purcell-factors (FP) up to FP=1050\n(average FP=272), single-photon purification, and cavity-enhanced quantum\nyields increasing from initially 1 % to 15 %. The utility of our nanoplasmonic\nplatform is applicable to other 2D material, including boron nitride, opening\nnew inroads in quantum photonics."
    },
    {
        "anchor": "Comment on `Aharonov--Casher-Effect Suppression of Macroscopic Tunneling\n  of Magnetic Flux': A recent Letter [1] has proposed a device, consisting of an rf SQUID with the\njunction replaced by a double one, i.e. a Bloch transistor. For symmetric\nJosephson couplings, and for specific flux bias and gate voltage applied to the\ntransistor's island, the tunneling of encircled flux between its two local\npotential minima is claimed to be suppressed completely due to destructive\ninterference. This comment purports to show that this claim in general is not\nvalid. Namely, the very Hamiltonian (1) in [1], from which the effect is\nderived, describes the circuit only under an additional condition.\n  [1] J.R. Friedman and D.V. Averin, Phys. Rev. Lett._88_, 050403 (2002).",
        "positive": "Plasmons in the van der Waals charge-density-wave material 2H-TaSe2: Plasmons in two-dimensional (2D) materials beyond graphene have recently\ngained much attention. However, the experimental investigation is limited due\nto the lack of suitable materials. Here, we experimentally demonstrate\nlocalized plasmons in a correlated 2D charge-density-wave (CDW) material:\n2H-TaSe2. The plasmon resonance can cover a broad spectral range from the\nterahertz (40 {\\mu}m) to the telecom (1.55 {\\mu}m) region, which is further\ntunable by changing thickness and dielectric environments. The plasmon\ndispersion flattens at large wave vectors, resulted from the universal\nscreening effect of interband transitions. More interestingly, anomalous\ntemperature dependence of plasmon resonances associated with CDW excitations is\nobserved. In the CDW phase, the plasmon peak close to the CDW excitation\nfrequency becomes wider and asymmetric, mimicking two coupled oscillators. Our\nstudy not only reveals the universal role of the intrinsic screening on 2D\nplasmons, but also opens an avenue for tunable plasmons in 2D correlated\nmaterials."
    },
    {
        "anchor": "Coulomb drag: Coulomb drag is a transport phenomenon whereby long-range Coulomb interaction\nbetween charge carriers in two closely spaced but electrically isolated\nconductors induces a voltage (or, in a closed circuit, a current) in one of the\nconductors when an electrical current is passed through the other. The\nmagnitude of the effect depends on the exact nature of the charge carriers and\nmicroscopic, many-body structure of the electronic systems in the two\nconductors. Drag measurements have become part of the standard toolbox in\ncondensed matter physics that can be used to study fundamental properties of\ndiverse physical systems including semiconductor heterostructures, graphene,\nquantum wires, quantum dots, and optical cavities.",
        "positive": "Ultra-High Density, High-Performance and Energy-Efficient All Spin Logic: All Spin Logic gates employ multiple nano-magnets interacting through\nspin-torque using non-magnetic channels. Compactness, non-volatility and\nultra-low voltage operation are some of the attractive features of ASL, while,\nlow switching-speed (of nano-magnets as compared to CMOS gates) and\nstatic-power dissipation can be identified as the major bottlenecks. In this\nwork we explore design techniques that leverage the specific device\ncharacteristics of ASL to overcome the inefficiencies and to enhance the merits\nof this technology, for a given set of device parameters. We exploit the\nnon-volatility of nano-magnets to model fully-pipelined ASL that can achieve\nhigher performance. Clocking of power supply in pipelined ASL would require\nCMOS transistors that may consume significantly large voltage headroom and\narea, as compared to the nano-magnets. We show that the use of leaky\ntransistors can significantly mitigate such bottlenecks, without sacrificing\nenergy-efficiency and robustness. Exploiting the inherent isolation between the\nbiasing charge current and spin-current paths in ASL, we propose to stack\nmultiple ASL metal layers, leading to ultra-high-density and energy-efficient\n3-D computation blocks. Results for the design of an FIR filter show that ASL\ncan achieve performance and power consumption comparable to CMOS while the\nultra-high-density of ASL can be projected as its main advantage over CMOS."
    },
    {
        "anchor": "Giant magnetoresistance and perfect spin filter in silicene, germanene,\n  and stanene: Silicene, germanene and stanene are two-dimensional topological insulators\nexhibiting helical edge states. We investigate global and local manipulations\nat the edges by exposing them to (i) a charge-density-wave order, (ii) a\nsuperconductor, (iii) an out-of-plane antiferromagnetic, and (iv) an in-plane\nantiferromagnetic field. We show that these perturbations affect the helical\nedge states in a different fashion. As a consequence one can realize quantum\nspin-Hall effect without edge states. In addition, these edge manipulations\nlead to very promising applications: a giant magnetoresistance and a perfect\nspin filter. We also investigate the effect of manipulations on a very few\nedge-sites of a topological insulator nanodisk.",
        "positive": "Resonant spin polarization and spin current in a two-dimensional\n  electron gas: We study the spin polarization and its associated spin-Hall current due to\nEDSR in disordered two-dimensional electron systems. We show that the disorder\ninduced damping of the resonant spin polarization can be strongly reduced by an\noptimal field configuration that exploits the interference between Rashba and\nDresselhaus spin-orbit interaction. This leads to a striking enhancement of the\nspin susceptibility while the spin-Hall current vanishes at the same time. We\ngive an interpretation of the spin current in geometrical terms which are\nassociated with the trajectories the polarization describes in spin space."
    },
    {
        "anchor": "Electronic structure effects in stability and quantum conductance in 2D\n  gold nanowires: We have investigated the stability and conductivity of unsupported, two\ndimensional infinite gold nanowires using ab-initio density functional theory\n(DFT). Two dimensional ribbon like nanowires, with 1-5 rows of gold atoms in\nthe non-periodic direction and with different possible structures have been\nconsidered. The nanowires with > 2 rows of atoms exhibit dimerization, similar\nto finite wires, along the non-periodic direction. Our results show that in\nthese zero thickness nanowires, the parallelogram motif is the most stable. A\ncomparison between parallelogram and rectangular shaped nanowires of increasing\nwidth indicates that zero thickness (111) oriented wires have a higher\nstability over (100). A detailed analysis of the electronic structure, reveals\nthat the (111) oriented structures show increased delocalization of s and p\nelectrons in addition to a stronger delocalization of the d electrons and hence\nare the most stable. The density of states show that the nanowires are metallic\nand conducting except for the double zigzag structure, which, is\nsemiconducting. Conductance calculations show transmission for a wide range of\nenergies in all the stable nanowires with more than two rows of atoms. The\nconductance channels are not purely s and have strong contributions from the d\nlevels and weak contributions from the p levels.",
        "positive": "Graphene nanosystems and low-dimensional Chern-Simons topological\n  insulators: A graphene nanoribbon is a good candidate for a $(1+1)$ Chern-Simons\ntopological insulator since it obeys particle-hole symmetry. We show that in a\nfinite semiconducting armchair ribbon, which has two zigzag edges and two\narmchair edges, a $(1+1)$ Chern-Simons topological insulator is indeed realized\nas the length of the armchair edges becomes large in comparison to that of the\nzigzag edges. But only a quasi-topological insulator is formed in a metallic\narmchair ribbon with a pseudogap. In such systems a zigzag edge acts like a\ndomain wall, through which the polarization changes from $0$ to $e/2$, forming\na fractional charge of one-half. When the lengths of the zigzag edges and the\narmchair edges are comparable a rectangular graphene sheet (RGS) is realized,\nwhich also possess particle-hole symmetry. We show that it is a $(0+1)$\nChern-Simons topological insulator. We find that the cyclic Berry phase of\nstates of a RGS is quantized as $\\pi$ or $0$ (mod $2\\pi$), and that the Berry\nphases of the particle-hole conjugate states are equal each other. By applying\nthe Atiyah-Singer index theorem to a rectangular ribbon and a RGS we find that\nthe lower bound on the number of nearly zero energy end states is approximately\nproportional to the length of the zigzag edges. However, there is a correction\nto this index theorem due to the effects beyond the effective mass\napproximation."
    },
    {
        "anchor": "Antibunched photons emitted by a dc biased Josephson junction: We show experimentally that a dc biased Josephson junction in series with a\nhigh-enough impedance microwave resonator emits antibunched photons. Our\nresonator is made of a simple micro-fabricated spiral coil that resonates at\n4.4 GHz and reaches a 1.97 k$\\Omega$ characteristic impedance. The second order\ncorrelation function of the power leaking out of the resonator drops down to\n0.3 at zero delay, which demonstrates the antibunching of the photons emitted\nby the circuit at a rate of 6 $10^7$ photons per second. Results are found in\nquantitative agreement with our theoretical predictions. This simple scheme\ncould offer an efficient and bright single-photon source in the microwave\ndomain.",
        "positive": "Impurity-assisted tunneling magnetoresistance under weak magnetic field: Injection of spins into semiconductors is essential for the integration of\nthe spin functionality into conventional electronics. Insulating layers are\noften inserted between ferromagnetic metals and semiconductors for obtaining an\nefficient spin injection, and it is therefore crucial to distinguish between\nsignatures of electrical spin injection and impurity-driven effects in the\ntunnel barrier. Here we demonstrate an impurity-assisted tunneling\nmagnetoresistance effect in nonmagnetic-insulator-nonmagnetic and\nferromagnetic-insulator-nonmagnetic tunnel barriers. In both cases, the effect\nreflects on/off switching of the tunneling current through impurity channels by\nthe external magnetic field. The reported effect, which is universal for any\nimpurity-assisted tunneling process, finally clarifies the controversy of a\nwidely used technique that employs the same ferromagnetic electrode to inject\nand detect spin accumulation."
    },
    {
        "anchor": "All-optical hyperpolarization of electron and nuclear spins in diamond: Low thermal polarization of nuclear spins is a primary sensitivity limitation\nfor nuclear magnetic resonance. Here we demonstrate optically pumped\n(microwave-free) nuclear spin polarization of $^{13}\\mathrm{C}$ and\n$^{15}\\mathrm{N}$ in $^{15}\\mathrm{N}$-doped diamond. $^{15}\\mathrm{N}$\npolarization enhancements up to $-2000$ above thermal equilibrium are observed\nin the paramagnetic system $\\mathrm{N_s}^{0}$. Nuclear spin polarization is\nshown to diffuse to bulk $^{13}\\mathrm{C}$ with NMR enhancements of $-200$ at\nroom temperature and $-500$ at $\\mathrm{240~K}$, enabling a route to\nmicrowave-free high-sensitivity NMR study of biological samples in ambient\nconditions.",
        "positive": "Anderson Transitions: The physics of Anderson transitions between localized and metallic phases in\ndisordered systems is reviewed. The term ``Anderson transition'' is understood\nin a broad sense, including both metal-insulator transitions and\nquantum-Hall-type transitions between phases with localized states. The\nemphasis is put on recent developments, which include: multifractality of\ncritical wave functions, criticality in the power-law random banded matrix\nmodel, symmetry classification of disordered electronic systems, mechanisms of\ncriticality in quasi-one-dimensional and two-dimensional systems and survey of\ncorresponding critical theories, network models, and random Dirac Hamiltonians.\nAnalytical approaches are complemented by advanced numerical simulations."
    },
    {
        "anchor": "Effect of high-k environment on charge carrier mobility in graphene: It is widely assumed that the dominant source of scattering in graphene is\ncharged impurities in a substrate. We have tested this conjecture by studying\ngraphene placed on various substrates and in high-k media. Unexpectedly, we\nhave found no significant changes in carrier mobility either for different\nsubstrates or by using glycerol, ethanol and water as a top dielectric layer.\nThis suggests that Coulomb impurities are not the scattering mechanism that\nlimits the mean free path currently attainable for graphene on a substrate.",
        "positive": "High-Performance, Hysteresis-Free Carbon Nanotube FETs via Directed\n  Assembly: High-performance single-wall carbon nanotube field-effect transistors\n(SWNT-FETs) are fabricated using directed assembly and mass-produced carbon\nnanotubes (CNTs). These FETs exhibit operating characteristics comparable to\nstate-of-the-art devices, and the process provides a route to large-scale\nfunctional CNT circuit assembly that circumvents problems inherent in processes\nrelying on chemical vapor deposition (CVD). Furthermore, the integration of\nhydrophobic self-assembled monolayers (SAMs) in the device structure eliminates\nthe primary source of gating hysteresis in SWNT-FETs, which leads to\nhysteresis-free FET operation while exposing unmodified nanotube surfaces to\nambient air."
    },
    {
        "anchor": "Spin Structure and Resonant Driving of Spin-1/2 Defects in SiC: Transition metal (TM) defects in silicon carbide have favorable spin\ncoherence properties and are suitable as quantum memory for quantum\ncommunication. To characterize TM defects as quantum spin-photon interfaces, we\nmodel defects that have one active electron with spin 1/2 in the atomic $D$\nshell. The spin structure, as well as the magnetic and optical resonance\nproperties of the active electron emerge from the interplay of the crystal\npotential and spin-orbit coupling and are described by a general model derived\nusing group theory. We find that the spin-orbit coupling leads to additional\nallowed transitions and a modification of the $g$-tensor. To describe the\ndependence of the Rabi frequency on the magnitude and direction of the static\nand driving fields, we derive an effective Hamiltonian. This theoretical\ndescription can also be instrumental to perform and optimize spin control in TM\ndefects.",
        "positive": "Power loss and electromagnetic energy density in a dispersive\n  metamaterial medium: The power loss and electromagnetic energy density of a metamaterial\nconsisting of arrays of wires and split-ring resonators (SRRs) are\ninvestigated. We show that a field energy density formula can be derived\nconsistently from both the electrodynamic (ED) approach and the equivalent\ncircuit (EC) approach. The derivations are based on the knowledge of the\ndynamical equations of the electric and magnetic dipoles in the medium and the\ncorrect form of the power loss. We discuss the role of power loss in\ndetermining the form of energy density and explain why the power loss should be\nidentified first in the ED derivation. When the power loss is negligible and\nthe field is harmonic, our energy density formula reduces to the result of\nLandau's classical formula. For the general case with finite power loss, our\ninvestigation resolves the apparent contradiction between the previous results\nderived by the EC and ED approaches."
    },
    {
        "anchor": "Spin precession in anisotropic media: We generalize the diffusive model for spin injection and detection in\nnonlocal spin structures to account for spin precession under an applied\nmagnetic field in an anisotropic medium, for which the spin lifetime is not\nunique and depends on the spin orientation.We demonstrate that the spin\nprecession (Hanle) line shape is strongly dependent on the degree of anisotropy\nand on the orientation of the magnetic field. In particular, we show that the\nanisotropy of the spin lifetime can be extracted from the measured spin signal,\nafter dephasing in an oblique magnetic field, by using an analytical formula\nwith a single fitting parameter. Alternatively, after identifying the\nfingerprints associated with the anisotropy, we propose a simple scaling of the\nHanle line shapes at specific magnetic field orientations that results in a\nuniversal curve only in the isotropic case. The deviation from the universal\ncurve can be used as a complementary means of quantifying the anisotropy by\ndirect comparison with the solution of our generalized model. Finally, we\napplied our model to graphene devices and find that the spin relaxation for\ngraphene on silicon oxide is isotropic within our experimental resolution.",
        "positive": "Magnetic moment and magnetic anisotropy of linear and zigzag 4{\\it d}\n  and 5{\\it d} transition metal nanowires: First-principles calculations: An extensive {\\it ab initio} study of the physical properties of both linear\nand zigzag atomic chains of all 4$d$ and 5$d$ transition metals (TM) within the\nGGA by using the accurate PAW method, has been carried out. All the TM linear\nchains are found to be unstable against the corresponding zigzag structures.\nAll the TM chains, except Nb, Ag and La, have a stable (or metastable) magnetic\nstate in either the linear or zigzag or both structures. Magnetic states appear\nalso in the sufficiently stretched Nb and La linear chains and in the largely\ncompressed Y and La chains. The spin magnetic moments in the Mo, Tc, Ru, Rh, W,\nRe chains could be large ($\\geq$1.0 $\\mu_B$/atom). Structural transformation\nfrom the linear to zigzag chains could suppress the magnetism already in the\nlinear chain, induce the magnetism in the zigzag structure, and also cause a\nchange of the magnetic state (ferromagnetic to antiferroamgetic or vice verse).\nThe calculations including the spin-orbit coupling reveal that the orbital\nmoments in the Zr, Tc, Ru, Rh, Pd, Hf, Ta, W, Re, Os, Ir and Pt chains could be\nrather large ($\\geq$0.1 $\\mu_B$/atom). Importantly, large magnetic anisotropy\nenergy ($\\geq$1.0 meV/atom) is found in most of the magnetic TM chains,\nsuggesting that these nanowires could have fascinating applications in\nultrahigh density magnetic memories and hard disks. In particular, giant\nmagnetic anisotropy energy ($\\geq$10.0 meV/atom) could appear in the Ru, Re,\nRh, and Ir chains. Furthermore, the magnetic anisotropy energy in several\nelongated linear chains could be as large as 40.0 meV/atom. A\nspin-reorientation transition occurs in the Ru, Ir, Ta, Zr, La and Zr, Ru, La,\nTa and Ir linear chains when they are elongated. Remarkably, all the 5$d$ as\nwell as Tc and Pd chains show the colossal magnetic anisotropy (i.e., it is\nimpossible to rotate magnetization into certain directions). Finally, the\nelectronic band structure and density of states of the nanowires have also been\ncalculated in order to understand the electronic origin of the large magnetic\nanisotropy and orbital magnetic moment as well as to estimate the conduction\nelectron spin polarization."
    },
    {
        "anchor": "Nanosize effect: Enhanced compensation temperature and existence of\n  magneto-dielectric coupling in SmFeO3: In transition metal oxides, quantum confinement arising from a large surface\nto volume ratio often gives rise to novel physico-chemical properties at\nnanoscale. Their size dependent properties have potential applications in\ndiverse areas, including therapeutics, imaging, electronic devices,\ncommunication systems, sensors, and catalysis. We have analyzed structural,\nmagnetic, dielectric, and thermal properties of weakly ferromagnetic SmFeO3\nnanoparticles of sizes about 55 nm and 500 nm. The nano-size particles exhibit\nseveral distinct features that are neither observed in their larger-size\nvariants nor reported previously for the single crystals. In particular, for\nthe 55 nm particle, we observe six-fold enhancement of compensation\ntemperature, an unusual rise in susceptibility in the temperature range 550 to\n630 K due to spin pinning, and coupled antiferromagnetic-ferroelectric\ntransition, directly observed in the dielectric constant.",
        "positive": "Effects of spin-orbit coupling and many-body correlations in STM\n  transport through copper phthalocyanine: The interplay of exchange correlations and spin-orbit interaction (SOI) on\nthe many-body spectrum of a copper phtalocyanine (CuPc) molecule and their\nsignatures in transport are investigated. We first derive a minimal model\nHamiltonian in a basis of frontier orbitals which is able to reproduce\nexperimentally observed singlet-triplet splittings; in a second step SOI\neffects are included perturbatively. Major consequences of the SOI are the\nsplitting of former degenerate levels and a magnetic anisotropy, which can be\ncaptured by an effective low-energy spin Hamiltonian. We show that STM-based\nmagnetoconductance measurements can yield clear signatures of both these SOI\ninduced effects."
    },
    {
        "anchor": "An Adiabatic Quantum Electron Pump: A quantum pumping mechanism which produces dc current or voltage in response\nto a cyclic deformation of the confining potential in an open quantum dot is\nreported. The voltage produced at zero current bias is sinusoidal in the phase\ndifference between the two ac voltages deforming the potential and shows random\nfluctuations in amplitude and direction with small changes in external\nparameters such as magnetic field. The amplitude of the pumping response\nincreases linearly with the frequency of the deformation. Dependencies of\npumping on the strength of the deformations, temperature, and breaking of\ntime-reversal symmetry are also investigated.",
        "positive": "Electronic structure of atomic manganese chains supported on Cu$_2$N /\n  Cu (100): Scanning tunnelling microscopy and density functional theory studies of\nmanganese chains adsorbed on Cu$_2$N/Cu (100) reveal an unsuspected electronic\nedge state at $\\sim 1$ eV above the Fermi energy. This Tamm-like state is\nstrongly localised to the last Mn atom of the chain and fully spin polarised.\nHowever, no equivalence is found for occupied states, and the electronic\nstructure at $\\sim -1$ eV is mainly spin unpolarised due to the extended\n$p$-states of the N atoms that mediate the coupling between the Mn atoms in the\nchain. Odd-numbered Mn chains present an exponentially decreasing direct\ncoupling with distance between the two edges, leading to a vanishing\nbonding/anti-bonding splitting of states while even-numbered Mn chains present\nperfect decoupling of both edges due to the the antiferromagnetic ordering of\nMn chains."
    },
    {
        "anchor": "Odd-frequency superconducting pairing in one-dimensional systems: Odd-frequency superconductivity represents a truly unconventional ordered\nstate which, in contrast to conventional superconductivity, exhibits pair\ncorrelations which are odd in relative time and, hence, inherently dynamical.\nIn this review article we provide an overview of recent advances in the study\nof odd-frequency superconducting correlations in one-dimensional systems. In\nparticular, we focus on recent developments in the study of nanowires with\nRashba spin-orbit coupling and metallic edges of two-dimensional topological\ninsulators in proximity to conventional superconductors. These systems have\nrecently elicited a great deal of interest due to their potential for realizing\none-dimensional topological superconductivity whose edges can host Majorana\nzero modes. We also provide a detailed discussion of the intimate relationship\nbetween Majorana zero modes and odd-frequency pairing. Throughout this review,\nwe highlight the ways in which odd-frequency pairing provides a deeper\nunderstanding of the unconventional superconducting correlations present in\neach of these intriguing systems and how the study and control of these states\nholds the potential for future applications.",
        "positive": "Hole-doping-induced half-metallic ferromagnetism in highly-air-stable\n  PdSe2 monolayer under uniaxial stress: Two-dimensional (2D) high-temperature ferromagnetic materials are important\nfor spintronic application. Fortunately, a highly-air-stable PdSe$_2$ monolayer\nsemiconductor has been made through exfoliation from the layered bulk material.\nIt is very highly desirable to realize robust ferromagnetism, even\nhalf-metallic ferromagnetism (100\\% spin polarization), in such excellent\nnonmagnetic monolayer semiconductors. Here, the first-principles investigation\nshows that the PdSe$_2$ monolayer can be made to attain Stoner ferromagnetism\nwith the maximal Curie temperature reaching to 800K, and the hole concentration\nthreshold for ferromagnetism decreases with applied uniaxial stress.\nFurthermore, half-metallicity can be achieved in some hole concentration\nregions. For the strain of 10\\% (uniaxial tensile stress of 4.4 N/m), the\nmonolayer can attain half-metallic ferromagnetism up to 150 K. The magnetic\nanisotropic energy is suitable to not only stabilizing the 2D ferromagnetism\nbut also realizing fast magnetization reversal. The magnetization can be also\ncontrolled by applying a transverse uniaxial stress. The highly-air-stable\nPdSe$_2$ monolayer, with these advantages, should be promising for spintronic\napplications."
    },
    {
        "anchor": "Accurate electronic band gaps of two-dimensional materials from the\n  local modified Becke-Johnson potential: The electronic band structures of two-dimensional materials are significantly\ndifferent from those of their bulk counterparts, due to quantum confinement and\nstrong modifications of electronic screening. An accurate determination of\nelectronic states is a prerequisite to design electronic or optoelectronic\napplications of two-dimensional materials, however, most of the theoretical\nmethods we have available to compute band gaps are either inaccurate,\ncomputationally expensive, or only applicable to bulk systems. Here we show\nthat reliable band structures of nanostructured systems can now be efficiently\ncalculated using density-functional theory with the local modified\nBecke-Johnson exchange-correlation functional that we recently proposed. After\nre-optimizing the parameters of this functional specifically for\ntwo-dimensional materials, we show, for a test set of almost 300 systems, that\nthe obtained band gaps are of comparable quality as those obtained using the\nbest hybrid functionals, but at a very reduced computational cost. These\nresults open the way for accurate high-throughput studies of band-structures of\ntwo-dimensional materials and for the study of van der Waals heterostructures\nwith large unit cells.",
        "positive": "Effects of Zeeman spin splitting on the modular symmetry in the quantum\n  Hall effect: Magnetic-field-induced phase transitions in the integer quantum Hall effect\nare studied under the formation of paired Landau bands arising from Zeeman spin\nsplitting. By investigating features of modular symmetry, we showed that\nmodifications to the particle-hole transformation should be considered under\nthe coupling between the paired Landau bands. Our study indicates that such a\ntransformation should be modified either when the Zeeman gap is much smaller\nthan the cyclotron gap, or when these two gaps are comparable."
    },
    {
        "anchor": "Acoustically modulated optical emission of hexagonal boron nitride\n  layers: We investigate the effect of surface acoustic waves on the atomic-like\noptical emission from defect centers in hexagonal boron nitride layers\ndeposited on the surface of a LiNbO$_3$ substrate. The dynamic strain field of\nthe surface acoustic waves modulates the emission lines resulting in intensity\nvariations as large as 50% and oscillations of the emission energy with an\namplitude of almost 1 meV. From a systematic study of the dependence of the\nmodulation on the acoustic wave power, we determine a hydrostatic deformation\npotential for defect centers in this two-dimensional material of about 40\nmeV/%. Furthermore, we show that the dynamic piezoelectric field of the\nacoustic wave could contribute to the stabilization of the optical properties\nof these centers. Our results show that surface acoustic waves are a powerful\ntool to modulate and control the electronic states of two-dimensional\nmaterials.",
        "positive": "Magnetoelectric effect in bilayer graphene controlled by valley-isospin\n  density: We show that bilayer graphene exhibits magneto-electric effects that are\nformally similar to those commonly seen in band insulators with broken\ninversion and time-reversal symmetries. Three unusual features characterize the\nmagneto-electric responses exhibited by bilayer graphene: (i) unlike most other\nmagneto-electric media, bilayer graphene is a conductor, (ii) bilayer graphene\nhas a non-quantized magneto-electric coupling even though its electronic\nstructure does not break parity and time-reversal symmetry, and (iii) the\nmagnitude of the magneto-electric coupling in bilayer graphene is determined by\nthe valley-isospin density, which can be manipulated experimentally. This last\nproperty also enables a purely electric measurement of valley-isospin\ndensities. While our theoretical arguments use bilayer graphene as an example,\nthey are generally valid for any material with similar symmetries."
    },
    {
        "anchor": "Dielectric response of Anderson and pseudogapped insulators: Using a combination of analytic and numerical methods, we study the\npolarizability of a (non-interacting) Anderson insulator in one, two, and three\ndimensions and demonstrate that, in a wide range of parameters, it scales\nproportionally to the square of the localization length, contrary to earlier\nclaims based on the effective-medium approximation. We further analyze the\neffect of electron-electron interactions on the dielectric constant in\nquasi-1D, quasi-2D and 3D materials with large localization length, including\nboth Coulomb repulsion and phonon-mediated attraction. The phonon-mediated\nattraction (in the pseudogapped state on the insulating side of the\nSuperconductor-Insulator Transition) produces a correction to the dielectric\nconstant, which may be detected from a linear response of a dielectric constant\nto an external magnetic field.",
        "positive": "Plasmon excitations in planar sodium clusters: The collective electronic excitation in planar sodium clusters is studied by\ntime-dependent density functional theory calculations. The formation and\ndevelopment of the resonances in photoabsorption spectra are investigated in\nterms of the shape and size of the 2-dimensional (2-D) systems. The nature of\nthese resonances is revealed by the frequency-resolved induced charge densities\npresent on a real-space grid. For long double chains, the excitation is similar\nto that in long single atomic chains, showing longitudinal modes, end and\ncentral transverse modes. However, for 2-D planes consisting of ($n \\times n$)\natoms with $n$ up to 16, new 2-D characteristic modes emerge regardless of the\nsymmetries considered. For a kick parallel to the plane, besides the equivalent\nend mode, mixed modes with contrary polarity occur, while for an impulse\nperpendicular to the plane there will be corner, side center, bulk center, and\ncircuit modes. Our calculation reveals the importance of dimensionality for\nplasmon excitation and how it evolves from 1-D to 2-D."
    },
    {
        "anchor": "Qubit Decoherence and Symmetry Restoration through Real-Time Instantons: A parametrically driven quantum oscillator, stabilized by a nonlinear\ndissipation, exhibits a spontaneous breaking of the parity symmetry. It results\nin the quantum bi-stability, corresponding to a Bloch sphere of dark states.\nThis makes such a driven-dissipative system an attractive candidate for a\nqubit. The parity symmetry breaking is exact both on the classical level and\nwithin the quantum mechanical perturbation theory. Here we show that\nnon-perturbative quantum effects lead to the symmetry restoration and result in\nexponentially small but finite qubit decoherence rate. Technically the symmetry\nrestoration is due to real time instanton trajectories of the Keldysh path\nintegral, which represents the Lindbladian evolution of the driven-dissipative\noscillator.",
        "positive": "Charge ordering and hopping in a triangular array of quantum dots: We demonstrate a mapping between the problem of charge ordering in a\ntriangular array of quantum dots and a frustrated Ising spin model. Charge\ncorrelation in the low temperature state is characterized by an intrinsic\nheight field order parameter. Different ground states are possible in the\nsystem, with a rich phase diagram. We show that electronic hopping transport is\nsensitive to the properties of the ground state, and describe the singularities\nof hopping conductivity at the freezing into an ordered state."
    },
    {
        "anchor": "Large Fourier transforms never exactly realized by braiding conformal\n  blocks: Fourier transform is an essential ingredient in Shor's factoring algorithm.\nIn the standard quantum circuit model with the gate set $\\{\\U(2),\n\\textrm{CNOT}\\}$, the discrete Fourier transforms $F_N=(\\omega^{ij})_{N\\times\nN},i,j=0,1,..., N-1, \\omega=e^{\\frac{2\\pi i}{N}}$, can be realized exactly by\nquantum circuits of size $O(n^2), n=\\textrm{log}N$, and so can the discrete\nsine/cosine transforms. In topological quantum computing, the simplest\nuniversal topological quantum computer is based on the Fibonacci\n(2+1)-topological quantum field theory (TQFT), where the standard quantum\ncircuits are replaced by unitary transformations realized by braiding conformal\nblocks. We report here that the large Fourier transforms $F_N$ and the discrete\nsine/cosine transforms can never be realized exactly by braiding conformal\nblocks for a fixed TQFT. It follows that approximation is unavoidable to\nimplement the Fourier transforms by braiding conformal blocks.",
        "positive": "Adiabatic Electron Dynamics in Antiferromagnetic Texture: Adiabatic dynamics of conduction electrons in antiferromagnetic (AFM)\nmaterials with slowly varying spin texture is developed. Quite different from\nthe ferromagnetic (FM) case, adiabaticity in AFM texture does not imply perfect\nalignment of conduction electron spins with background profile, instead, it\nintroduces an internal dynamics between degenerate bands. As a result, the\norbital motion of conduction electrons becomes spin-dependent and is affected\nby two emergent gauge fields: one of them is the non-Abelian version of what\nhas been discovered in FM systems; the other leads to an anomalous velocity\nthat has no FM counterpart. Two examples with experimental predictions are\nprovided."
    },
    {
        "anchor": "Spin-Electric Coupling in Molecular Magnets: We study the triangular antiferromagnet Cu$_3$ in external electric fields,\nusing symmetry group arguments and a Hubbard model approach. We identify a\nspin-electric coupling caused by an interplay between spin exchange, spin-orbit\ninteraction, and the chirality of the underlying spin texture of the molecular\nmagnet. This coupling allows for the electric control of the spin (qubit)\nstates, e.g. by using an STM tip or a microwave cavity. We propose an\nexperimental test for identifying molecular magnets exhibiting spin-electric\neffects.",
        "positive": "Dynamics of quantum dot superradiance: The possibility of realizing the superradiant regime of electromagnetic\nemission by the assembly of quantum dots is considered. The overall dynamical\nprocess is analyzed in detail. It is shown that there can occur several\nqualitatively different stages of evolution. The process starts with dipolar\nwaves triggering the spontaneous radiation of individual dots. This corresponds\nto the fluctuation stage, when the dots are not yet noticeably correlated with\neach other. The second is the quantum stage, when the dot interactions through\nthe common radiation field become more important, but the coherence is not yet\ndeveloped. The third is the coherent stage, when the dots radiate coherently,\nemitting a superradiant pulse. After the superradiant pulse, the system of dots\nrelaxes to an incoherent state in the relaxation stage. If there is no external\npermanent pumping, or the effective dot interactions are weak, the system tends\nto a stationary state during the last stationary stage, when coherence dies out\nto a low, practically negligible, level. In the case of permanent pumping,\nthere exists the sixth stage of pulsing superradiance, when the system of dots\nemits separate coherent pulses."
    },
    {
        "anchor": "A nontrivial crossover in topological Hall effect regimes: We propose a new theory of the topological Hall effect (THE) in systems with\nchiral magnetization vortices such as magnetic skyrmions. We solve the problem\nof electron scattering on a magnetic skyrmion exactly, for an arbitrary\nstrength of exchange interaction and the skyrmion size. We report the existence\nof different regimes of THE and resolve the apparent contradiction between the\nadiabatic Berry phase theoretical approach and the perturbation theory for THE.\nWe traced how the topological charge Hall effect transforms into the spin Hall\neffect upon varying the exchange interaction strength or the skyrmion size.\nThis transformation has a nontrivial character: it is accompanied by an\noscillating behavior of both charge and spin Hall currents. This hallmark of\nTHE allows one to differentiate the chirality driven contribution to Hall\nresponse in the experiments.",
        "positive": "Observation of Collective Excitations of the Dilute 2D Electron System: We report inelastic light scattering measurements of dispersive spin and\ncharge density excitations in dilute 2D electron systems reaching densities\nless than 10^{10} cm^{-2}. In the quantum Hall state at nu=2, roton critical\npoints in the spin inter--Landau level mode show a pronounced softening as r_s\nis increased. Instead of a soft mode instability predicted by Hartree--Fock\ncalculations for r_s ~ 3.3, we find evidence of multiple rotons in the\ndispersion of the softening spin excitations. Extrapolation of the data\nindicates the possibility of an instability for r_s >~ 11."
    },
    {
        "anchor": "Renormalized transport properties of randomly gapped 2D Dirac fermions: We investigate the scaling properties of the recently acquired fermionic\nnon--linear $\\sigma$--model which controls gapless diffusive modes in a\ntwo--dimensional disordered system of Dirac electrons beyond charge neutrality.\nThe transport on large scales is governed by a novel renormalizable nonlocal\nfield theory. For zero mean random gap, it is characterized by the absence of a\ndynamic gap generation and a scale invariant diffusion coefficient. The $\\beta$\nfunction of the DC conductivity, computed for this model, is in perfect\nagreement with numerical results obtained previously.",
        "positive": "Unusual Electronic Structure of Few-Layer Grey Arsenic: A Computational\n  Study: We use ab initio density functional theory to study the equilibrium geometry\nand electronic structure of few-layer grey arsenic. In contrast to the bulk\nstructure that is semimetallic, few-layer grey As displays a significant band\ngap that depends sensitively on the number of layers, in-layer strain, layer\nstacking and inter-layer spacing. A metal-semiconductor transition can be\nintroduced by changing the number of layers or the in-layer strain. We\ninterpret this transition by an abrupt change in the spatial distribution of\nelectronic states near the top of the valence band."
    },
    {
        "anchor": "Scalable qubit architecture based on holes in quantum dot molecules: Spins confined in quantum dots are a leading candidate for solid-state\nquantum bits that can be coherently controlled by optical pulses. There are,\nhowever, many challenges to developing a scalable multibit information\nprocessing device based on spins in quantum dots, including the natural\ninhomogeneous distribution of quantum dot energy levels, the difficulty of\ncreating all-optical spin manipulation protocols compatible with nondestructive\nreadout, and the substantial electron-nuclear hyperfine interaction-induced\ndecoherence. Here, we present a scalable qubit design and device architecture\nbased on the spin states of single holes confined in a quantum dot molecule.\nThe quantum dot molecule qubit enables a new strategy for optical coherent\ncontrol with dramatically enhanced wavelength tunability. The use of hole spins\nallows the suppression of decoherence via hyperfine interactions and enables\ncoherent spin rotations using Raman transitions mediated by a hole-spin-mixed\noptically excited state. Because the spin mixing is present only in the\noptically excited state, dephasing and decoherence are strongly suppressed in\nthe ground states that define the qubits and nondestructive readout is\npossible. We present the qubit and device designs and analyze the wavelength\ntunability and fidelity of gate operations that can be implemented using this\nstrategy. We then present experimental and theoretical progress toward\nimplementing this design.",
        "positive": "Non-orthogonal Spin-Momentum Locking: Spin-momentum locking is a unique intrinsic feature of strongly spin-orbit\ncoupled materials and a key to their promise of applications in spintronics and\nquantum computation. Much of the existing work, in topological and\nnon-topological pure materials, has been focused on the orthogonal locking in\nthe vicinity of the $\\Gamma$ point where the directions of spin and momentum\nvectors are locked perpendicularly. With the orthogonal case, enforced by the\nsymmetry in pure systems, mechanisms responsible for non-orthogonal\nspin-momentum locking (NOSML) have drawn little attention, although it has been\nreported on the topological surface of $\\alpha$-$Sn$. Here, we demonstrate\nthat, the presence of the spin-orbit scattering from dilute spinless impurities\ncan produce the NOSML state in the presence of a strong intrinsic spin-orbit\ncoupling in the pristine material. We also observe an interesting coupling\nthreshold for the NOSML state to occur.\n  The relevant parameter in our analysis is the deflection angle from\northogonality which can be extracted experimentally from the\nspin-and-angle-resolved photoemission (S-ARPES) spectra. Our formalism is\napplicable to all strongly spin-orbit coupled systems with impurities and not\nlimited to topological ones. The understanding of NOSML bears on spin-orbit\ndependent phenomena, including issues of spin-to-charge conversion and the\ninterpretation of quasiparticle interference (QPI) patterns as well as\nscanning-tunneling spectra (STS) in general spin-orbit coupled materials."
    },
    {
        "anchor": "Linear scaling between momentum and spin scattering in graphene: Spin transport in graphene carries the potential of a long spin diffusion\nlength at room temperature. However, extrinsic relaxation processes limit the\ncurrent experimental values to 1-2 um. We present Hanle spin precession\nmeasurements in gated lateral spin valve devices in the low to high (up to\n10^13 cm^-2) carrier density range of graphene. A linear scaling between the\nspin diffusion length and the diffusion coefficient is observed. We measure\nnearly identical spin- and charge diffusion coefficients indicating that\nelectron-electron interactions are relatively weak and transport is limited by\nimpurity potential scattering. When extrapolated to the maximum carrier\nmobilities of 2x10^5 cm^2/Vs, our results predict that a considerable increase\nin the spin diffusion length should be possible.",
        "positive": "Layer-by-layer disentanglement of Bloch states via frequency-domain\n  photoemission: Layer-by-layer material engineering has enabled exotic quantum phenomena such\nas interfacial superconductivity and the quantum anomalous Hall effect.\nMeanwhile, deciphering electronic states layer-by-layer remains a fundamental\nscientific challenge. This is exemplified by the difficulty in understanding\nthe layer origins of topological electronic states in magnetic topological\ninsulators, which is key to understanding and controlling topological quantum\nphases. Here, we report a layer-encoded frequency-domain ARPES experiment on a\nmagnetic topological insulator (MnBi2Te4)(Bi2Te3) to characterize the layer\norigins of electronic states. Infrared laser excitations launch coherent\nlattice vibrations with the layer index encoded by the vibration frequency;\nphotoemission spectroscopy tracks the electron dynamics, where the layer\ninformation is decoded in the frequency domain. This layer-frequency\ncorrespondence reveals a surprising wavefunction relocation of the topological\nsurface state from the top magnetic layer into the buried second layer,\nreconciling the controversy over the vanishing broken-symmetry energy gap in\n(MnBi2Te4)(Bi2Te3) and its related compounds. The layer-frequency\ncorrespondence can be harnessed to disentangle electronic states layer-by-layer\nin a broad class of van der Waals superlattices."
    },
    {
        "anchor": "Conductance oscillation and quantization in monoatomic Al wires: We present first-principles calculations for the transport properties of\nmonoatomic Al wires sandwiched between Al(100) electrodes. The conductance of\nthe monoatomic Al wires oscillates with the number of the constituent atoms as\na function of the wire length, either with a period of four-atom for wires with\nthe typical interatomic spacing or a period of six-atom with the interatomic\nspacing of the bulk fcc aluminum, indicating a dependence of the period of\nconductance oscillation on the interatomic distance of the monoatomic Al wires.",
        "positive": "Kondo effect in real quantum dots: Exchange interaction within a quantum dot strongly affects the transport\nthrough it in the Kondo regime. In a striking difference with the results of\nthe conventional model, where this interaction is neglected, here the\ntemperature and magnetic field dependence of the conductance may become\nnon-monotonic: its initial increase follows by a drop when temperature and\nmagnetic field are lowered."
    },
    {
        "anchor": "Electrostatics of Inhomogeneous Quantum Hall Liquid: The distribution of electron density in the quantum Hall liquid is considered\nin the presence of macroscopic density gradient caused by side electrodes or\ninhomogeneous doping. In this case different Landau levels are occupied in\ndifferent regions of a sample. These regions are separated by incompressible\nliquid. It is shown that the applicability of the approach by Chklovskii et al.\nis substantially restricted if the density gradient is not very large and\ndisorder is important. Due to the fluctuations of the remote donor's density\nthe liquid in the transition region can not be considered as completely\nincompressible. In the typical situation, when the gap between Landau levels is\nnot much larger than the energy of disorder, the transition region is a wide\nband where electron density, averaged over the fluctuations, is independent of\nmagnetic field. The band is a random mixture of regions occupied by electrons\nof upper level, by holes of lower level and by incompressible liquid. The width\nof this band is calculated and an analytical expression for the fraction of\nincompressible liquid in different parts of this band is given.",
        "positive": "Detecting THz current fluctuations in a quantum point contact using a\n  nanowire quantum dot: We use a nanowire quantum dot to probe high-frequency current fluctuations in\na nearby quantum point contact. The fluctuations drive charge transitions in\nthe quantum dot, which are measured in real-time with single-electron detection\ntechniques. The quantum point contact (GaAs) and the quantum dot (InAs) are\nfabricated in different material systems, which indicates that the interactions\nare mediated by photons rather than phonons. The large energy scales of the\nnanowire quantum dot allow radiation detection in the long-wavelength infrared\nregime."
    },
    {
        "anchor": "Current-induced one-dimensional diffusion of Co ad-atoms on graphene\n  nanoribbons: One-dimensional diffusion of Co ad-atoms on graphene nanoribbons has been\ninduced and investigated by means of scanning tunnelling microscopy (STM). To\nthis end, the nanoribbons and the Co ad-atoms have been imaged before and after\ninjecting current pulses into the nanoribbons, with the STM tip in direct\ncontact with the ribbon. We observe current-induced motion of the Co atoms\nalong the nanoribbons, which is approximately described by a distribution\nexpected for a thermally activated one-dimensional random walk. This indicates\nthat the nanoribbons reach temperatures far beyond 100 K, which is well above\nthe temperature of the underlying Au substrate. This model system can be\ndeveloped further for the study of electromigration at the single-atom level.",
        "positive": "Spin-polarized Dirac-cone-like surface state with $d$ character at\n  W(110): The surface of W(110) exhibits a Dirac-cone-like surface state with $d$\ncharacter within a spin-orbit-induced symmetry gap. As a function of wave\nvector parallel to the surface, it shows nearly massless energy dispersion and\na pronounced spin polarization, which is antisymmetric with respect to the\nBrillouin zone center. In addition, the observed constant energy contours are\nstrongly anisotropic for all energies. This discovery opens new pathways to the\nstudy of surface spin-density waves arising from a strong Fermi surface nesting\nas well as $d$-electron-based topological properties."
    },
    {
        "anchor": "Majorana and parafermion corner states from two coupled sheets of\n  bilayer graphene: We consider a setup consisting of two coupled sheets of bilayer graphene in\nthe regime of strong spin-orbit interaction, where electrostatic confinement is\nused to create an array of effective quantum wires. We show that for suitable\ninterwire couplings the system supports a topological insulator phase\nexhibiting Kramers partners of gapless helical edge states, while the\nadditional presence of a small in-plane magnetic field and weak\nproximity-induced superconductivity leads to the emergence of zero-energy\nMajorana corner states at all four corners of a rectangular sample, indicating\nthe transition to a second-order topological superconducting phase. The\npresence of strong electron-electron interactions is shown to promote the above\nphases to their exotic fractional counterparts. In particular, we find that the\nsystem supports a fractional topological insulator phase exhibiting\nfractionally charged gapless edge states and a fractional second-order\ntopological superconducting phase exhibiting zero-energy $\\mathbb{Z}_{2m}$\nparafermion corner states, where $m$ is an odd integer determined by the\nposition of the chemical potential.",
        "positive": "Transport phenomena in nanotube quantum dots from strong to weak\n  confinement: We report low-temperature transport experiments on single-wall nanotubes with\nmetallic leads of varying contact quality, ranging from weak tunneling to\nalmost perfect transmission. In the weak tunneling regime, where Coulomb\nblockade dominates, the nanotubes act as one-dimensional quantum dots. For\nstronger coupling to the leads the conductance can be strongly enhanced by\ninelastic cotunneling and the Kondo effect. For open contacts Coulomb blockade\nis completely suppressed, and the low-temperature conductance remains generally\nhigh, although we often see distinct dips in the conductance versus gate\nvoltage which may result from resonant backscattering."
    },
    {
        "anchor": "Dissipative topological systems: Topological phases of matter are protected from local perturbations and\ntherefore have been thought to be robust against decoherence. However, it has\nnot been systematically explored whether and how topological states are\ndynamically robust against the environment-induced decoherence. In this Letter,\nwe develop a theory for topological systems that incorporate dissipations,\nnoises and thermal effects. We derive novelly the exact master equation and the\ntransient quantum transport for the study of dissipative topological systems,\nmainly focusing on noninteracting topological insulators and topological\nsuperconductors. The resulting exact master equation and the transient\ntransport current are also applicable for the systems initially entangled with\nenvironments. We apply the theory to the topological Haldane model (Chern\ninsulator) and the quantized Majorana conductance to explore topological phases\nof matter that incorporate dissipations, noises and thermal effects, and\ndemonstrate the dissipative dynamics of topological states.",
        "positive": "Conductance statistics near the Anderson transition: Paper reviews recent numerical data for the conductance distribution of\ndisordered systems in the critical regime and in the localized regime. Of\nparticular interest is the non-analytical form of the critical conductance\ndistribution in the 3D and 4D systems, non-Gaussian form of the distribution of\nP(ln g) in localized 3D systems."
    },
    {
        "anchor": "Electron Spin Resonance of P Donors in Isotopically Purified Si Detected\n  by Contactless Photoconductivity: Coherence times of electron spins bound to phosphorus donors have been\nmeasured, using a standard Hahn echo technique, to be up to 20 ms in\nisotopically pure silicon with [P]$ = 10^{14}$ cm$^{-3}$ and at temperatures\n$\\leq 4 $K. Although such times are exceptionally long for electron spins in\nthe solid state, they are nevertheless limited by donor electron spin-spin\ninteractions. Suppressing such interactions requires even lower donor\nconcentrations, which lie below the detection limit for typical electron spin\nresonance (ESR) spectrometers. Here we describe an alternative method for\nphosphorus donor ESR detection, exploiting the spin-to-charge conversion\nprovided by the optical donor bound exciton transition. We characterise the\nmethod and its dependence on laser power and use it to measure a coherence time\nof $T_2 = 130 $ms for one of the purest silicon samples grown to-date ([P]$ =\n5\\times 10^{11} $cm$^{-3}$). We then benchmark this result using an alternative\napplication of the donor bound exciton transition: optically polarising the\ndonor spins before using conventional ESR detection at 1.7~K for a sample with\n[P]$ = 4\\times10^{12} $cm$^{-3}$, and measuring in this case a $T_2$ of 350 ms.",
        "positive": "Nonequilibrium Seebeck and spin Seebeck effects in nanoscale junctions: The spin-resolved thermoelectric transport properties of correlated nanoscale\njunctions, consisting of a quantum dot/molecule asymmetrically coupled to\nexternal ferromagnetic contacts, are studied theoretically in the\nfar-from-equilibrium regime. One of the leads is assumed to be strongly coupled\nto the quantum dot resulting in the development of the Kondo effect. The\nspin-dependent current flowing through the system, as well as the\nthermoelectric properties, are calculated by performing a perturbation\nexpansion with respect to the weakly coupled electrode, while the Kondo\ncorrelations are captured accurately by using the numerical renormalization\ngroup method. In particular, we determine the differential and nonequilibrium\nSeebeck effects of the considered system in different magnetic configurations\nand uncover the crucial role of spin-dependent tunneling on the device\nperformance. Moreover, by allowing for spin accumulation in the leads, which\ngives rise to finite spin bias, we shed light on the behavior of the\nnonequilibrium spin Seebeck effect."
    },
    {
        "anchor": "Magnetocapacitance of a graphene monolayer: We present a theoretical study of magnetocapacitance in a graphene monolayer\nat finite temperature taking into account the effects of disorder. The density\nof states (DOS) and magnetocapacitance found for graphene are compared to those\nfound in standard two dimensional electron gas (2DEG) systems. The magnetic\noscillations in DOS and magnetocapacitance are found to be enhanced and much\nmore robust with respect to temperature damping in monolayer graphene in\ncomparison with a 2DEG. Furthermore, we find that there is a $\\pi$ phase shift\nbetween magnetic oscillations in the two systems which can be attributed to\nDirac electrons in graphene acquiring a Berry's phase as they traverse a closed\npath in a magnetic field.",
        "positive": "Characterization of Bernstein modes in quantum dots: The dipole modes of non-parabolic quantum dots are studied by means of their\ncurrent and density patterns as well as with their local absorption\ndistribution. The anticrossing of the so-called Bernstein modes originates from\nthe coupling with electron-hole excitations of the two Landau bands which are\noccupied at the corresponding magnetic fields. Non-quadratic terms in the\npotential cause an energy separation between bulk and edge current modes in the\nanticrossing region. On a local scale the fragmented peaks absorb energy in\ncomplementary spatial regions which evolve with the magnetic field."
    },
    {
        "anchor": "Electric control of spin states in frustrated triangular molecular\n  magnets: Frustrated triangular molecular magnets are a very important class of\nmagnetic molecules since the absence of inversion symmetry allows an external\nelectric field to couple directly with the spin chirality that characterizes\ntheir ground state. The spin-electric coupling in these molecular magnets leads\nto an efficient and fast method of manipulating spin states, making them an\nexciting candidate for quantum information processing. The efficiency of the\nspin-electric coupling depends on the electric dipole coupling between the\nchiral ground states of these molecules. In this paper, we report on\nfirst-principles calculations of spin-electric coupling in $\\{V_3\\}$ triangular\nmagnetic molecule. We have explicitly calculated the spin-induced charge\nredistribution within the magnetic centers that is responsible for the\nspin-electric coupling. Furthermore, we have generalized the method of\ncalculating the strength of the spin-electric coupling to calculate any\ntriangular spin 1/2 molecule with $C_3$ symmetry and have applied it to\ncalculate the coupling strength in $\\{V_{15}\\}$ molecular magnets.",
        "positive": "Fabrication of quantum dots in undoped Si/Si$_{0.8}$Ge$_{0.2}$\n  heterostructures using a single metal-gate layer: Enhancement-mode Si/SiGe electron quantum dots have been pursued extensively\nby many groups for \\revEdit{their} potential in quantum computing. Most of the\nreported dot designs utilize multiple metal-gate layers and use Si/SiGe\nheterostructures with Ge concentration close to 30\\%. Here we report the\nfabrication and low-temperature characterization of quantum dots in\nSi/Si$_{0.8}$Ge$_{0.2}$ heterostructures using only one metal-gate layer. We\nfind that the threshold voltage of a channel narrower than 1 $\\mu$m increases\nas the width decreases. The higher threshold can be attributed to the\ncombination of quantum confinement and disorder. We also find that the lower Ge\nratio used here leads to a narrower operational gate bias range. The higher\nthreshold combined with the limited gate bias range constrains the device\ndesign of lithographic quantum dots. We incorporate such considerations in our\ndevice design and demonstrate a quantum dot that can be tuned from a single dot\nto a double dot. The device uses only a single metal-gate layer, greatly\nsimplifying device design and fabrication."
    },
    {
        "anchor": "Scaling analysis of negative differential thermal resistance: Negative differential thermal resistance (NDTR) can be generated for any\none-dimensional heat flow with a temperature-dependent thermal conductivity. In\na system-independent scaling analysis, the general condition for the occurrence\nof NDTR is found to be an inequality with three scaling exponents:\n$n_{1}n_{2}<-(1+n_{3})$, where $n_{1}\\in(-\\infty,+\\infty)$ describes a\nparticular way of varying the temperature difference, and $n_{2}$ and $n_{3}$\ndescribe, respectively, the dependence of the thermal conductivity on an\naverage temperature and on the temperature difference. For cases with a\ntemperature-dependent thermal conductivity, i.e. $n_{2}\\neq0$, NDTR can\n\\emph{always} be generated with a suitable choice of $n_{1}$ such that this\ninequality is satisfied. The results explain the illusory absence of a NDTR\nregime in certain lattices and predict new ways of generating NDTR, where such\npredictions have been verified numerically. The analysis will provide insights\nfor a designing of thermal devices, and for a manipulation of heat flow in\nexperimental systems, such as nanotubes.",
        "positive": "Image-charge detection of the Rydberg transition of electrons on\n  superfluid helium confined in a microchannel structure: The image-charge detection provides a new direct method for the detection of\nthe Rydberg transition in electrons trapped on the surface of liquid helium.\nThe interest in this method is motivated by the possibility to accomplish the\nspin state readout for a single trapped electron, thus opening a new pathway\ntowards using electron spins on liquid helium for quantum computing. Here, we\nreport on the image-charge detection of the Rydberg transition in a\nmany-electron system confined in an array of 20-um wide and 4-um deep channels\nfilled with superfluid helium. Such detection is made possible because of a\nsignificant enhancement of the image-charge signal due to close proximity of\ntrapped electrons to the electrodes embedded in the microchannel structure. The\ntransition frequency of electrons in the range of 400-500~GHz is highly\ncontrollable by the dc bias voltages applied to the device and is in a good\nagreement with our calculations. This work demonstrates that microchannel\nstructures provide a suitable platform for electron manipulation and their\nquantum state detection, with a feasibility of scaling the detection method to\na single electron."
    },
    {
        "anchor": "Elasto-Dynamical Induced Spin and Charge Pumping in Bulk Heavy Metals: Analogous to the Spin-Hall Effect (SHE), {\\it ab initio} electronic structure\ncalculations reveal that acoustic phonons can induce charge (spin) current\nflowing along (normal to) its propagation direction. Using Floquet approach we\nhave calculated the elastodynamical-induced charge and spin pumping in bulk Pt\nand demonstrate that: (i) While the longitudinal charge pumping is an intrinsic\nobservable, the transverse pumped spin-current has an extrinsic origin that\ndepends strongly on the electronic relaxation time; (ii) The longitudinal\ncharge current\n  is of nonrelativstic origin, while the transverse spin current is a\nrelativistic effect that to lowest order scales linearly with the spin-orbit\ncoupling strength; (iii) both charge and spin pumped currents have parabolic\ndependence on the amplitude of the elastic wave.",
        "positive": "Light-hole transitions in quantum dots: realizing full control by highly\n  focused optical-vortex beams: An optical-vortex is an inhomogeneous light beam having a phase singularity\nat its axis, where the intensity of the electric and/or magnetic field may\nvanish. Already well studied are the paraxial beams, which are known to carry\nwell defined values of spin (polarization $\\sigma$) and orbital angular\nmomenta; the orbital angular momentum per photon is given by the topological\ncharge $\\ell$ times the Planck constant. Here we study the\nlight-hole--to--conduction band transitions in a semiconductor quantum dot\ninduced by a highly-focused beam originating from a $\\ell=1$ paraxial optical\nvortex. We find that at normal incidence the pulse will produce two distinct\ntypes of electron--hole pairs, depending on the relative signs of $\\sigma$ and\n$\\ell$. When sign($\\sigma$)$=$sign($\\ell$), the pulse will create\nelectron--hole pairs with band+spin and envelope angular momenta both equal to\none. In contrast, for sign($\\sigma$)$\\neq$sign($\\ell$), the electron-hole pairs\nwill have neither band+spin nor envelope angular momenta. A tightly-focused\noptical-vortex beam thus makes possible the creation of pairs that cannot be\nproduced with plane waves at normal incidence. With the addition of\nco-propagating plane waves or switching techniques to change the charge $\\ell$\nboth the band+spin and the envelope angular momenta of the pair wave-function\ncan be precisely controlled. We discuss possible applications in the field of\nspintronics that open up."
    },
    {
        "anchor": "Coherent coupling dynamics in a quantum dot microdisk laser: Luminescence intensity autocorrelation (LIA) is employed to investigate\ncoupling dynamics between (In,Ga)As QDs and a high-Q (~7000) resonator with\nultrafast time resolution (150 fs), below and above the lasing threshold at T =\n5 K. For QDs resonant and non-resonant with the cavity we observe both a\nsix-fold enhancement and a 0.77 times reduction of the spontaneous emission\nrate, respectively. In addition, LIA spectroscopy reveals the onset of coherent\ncoupling at the lasing threshold through qualitative changes in the dynamic\nbehavior and a tripling of the resonant QD emission rate.",
        "positive": "Heat production and energy balance in nanoengines driven by\n  time-dependent fields: We present a formalism to study the heat transport and the power developed by\nthe local driving fields on a quantum system coupled to macroscopic reservoirs.\nWe show that, quite generally, two important mechanisms can take place: (i)\ndirected heat transport between reservoirs induced by the ac potentials and\n(ii) at slow driving, two oscillating out of phase forces perform work against\neach other, while the energy dissipated into the reservoirs is negligible"
    },
    {
        "anchor": "Dipolar interaction and demagnetizing effects in magnetic nanoparticle\n  dispersions: introducing the Mean Field Interacting Superparamagnet Model\n  (MFISP Model): A model is developed with the aim of analyzing interacting superparamagnets.\nModel is built from magnetic dipolar interaction and demagnetizing mean field\nconcepts. A useful expression for effective demagnetizing factors is achieved,\nwhich allows for the analysis of non uniform spatial distributions of\nnanoparticles. This expression is a function of demagnetizing factors\nassociated with specimen and clusters shapes, and of the mean distances between\nnear neighbor nanoparticles and between clusters, relative to the\ncharacteristic sizes of each of these two types of objects, respectively. It\nexplains effects of magnetic dipolar interactions such as the observation of\napparent nanoparticle magnetic-moments smaller than real ones. It is shown that\nby performing a minimum set of experimental determinations, model application\nallows retrieval of intrinsic properties, like magnetic moment and\nsusceptibility in the absence of interactions. It also permits the estimation\nof mean interparticle and intercluster relative distances, and of demagnetizing\nfactors associated with clusters shape. An expression for magnetic dipolar\nenergy per nanoparticle is also derived. Model experimental test was performed\nby analysis of results reported in the literature and of original results. They\ncorrespond to magnetite particles dispersed in PEGDA-600 polymer, and in PVA\nferrogels. Experimental results display different magnetic response when prism\nshaped specimens are measured along principal directions. Intrinsic properties\nand structural information were retrieved from the analysis, in excellent\nagreement with information obtained from FESEM images. In the studied samples\nnanoparticles were found to be in close contact to each other within almost\nrandomly oriented clusters. Intercluster mean relative-distance was found to\nvary between 2.2 and 7.5, depending on particles volume fraction.",
        "positive": "Modeling the shape of axisymmetric skyrmions in magnetic multilayers: We present a comprehensive micromagnetic model of isolated axisymmetric\nskyrmions in magnetic multilayers with perpendicular anisotropy. Most notably,\nthe essential role of the internal dipolar field is extensively considered with\na minimum amount of assumptions on the magnetization profiles. The\ntri-dimensional structure of the multilayered skyrmions is modeled by their\nradial profiles in each layer. We first compare the results of the model\nagainst a full micromagnetic description in Cartesian coordinates. Our model\ncombines information on both layer-dependent size and chirality of the\nskyrmions. We also provide a convenient criterion in order to characterize the\nstability of skyrmions against anisotropic elongations that would break their\ncylindrical symmetry, which allows to confirm the stability of the determined\nsolutions. Because this model is able to treat magnetization configurations\ntwisted through the thickness of multilayered skyrmions, it can provide\npredictions on any potential hybrid chirality in skyrmions due to the interplay\nof Dzyaloshinskii-Moriya and dipolar interactions in multilayers. We finally\napply the results of our model to the description of the current-driven\ndynamics of hybrid chiral skyrmions. Using the Thiele formalism, we show that\nwe can predict the forces exerted on the multilayered skyrmions by vertical\nspin-polarized currents, which provides a method to conform hybrid skyrmion\nchiralities and spin-current injection geometries in order to optimize skyrmion\nmotion in multilayers, to the aim of maximizing the current-induced velocity,\nor canceling the skyrmion Hall angle."
    },
    {
        "anchor": "Negative differential conductance in molecular junctions: an overview of\n  experiment and theory: One of the ultimate goals of molecular electronics is to create technologies\nthat will complement - and eventually supersede - Si-based microelectronics\ntechnologies. To reach this goal, electronic properties that mimic at least\nsome of the electrical behaviors of today's semiconductor components must be\nrecognized and characterized. AN outstanding example for one such behavior is\nnegative differential conductance (NDC), in which an increase in voltage across\nthe device terminals results in a decrease in the electrical current passing\nthrough the device. This overview focuses on the NDC phenomena observed in\nmetal-single molecule-metal junctions, and is roughly divided into two parts.\nIn the first part, the central experiments which demonstrate NDC in\nsingle-molecule junctions are critically overviewed, with emphasis on the main\nobservations and their possible physical origins. The second part is devoted to\nthe theory of NDC in single-molecule junctions, where simple models are\nemployed to shed light on possible mechanisms leading to NDC.",
        "positive": "Coulombic effects on magnetoconductivity oscillations induced by\n  microwave excitation in multisubband two-dimensional electron systems: We develop a theory of magneto-oscillations in photoconductivity of\nmultisubband two-dimensional electron systems which takes into account strong\nCoulomb interaction between electrons. In the presence of a magnetic field\noriented perpendicular, internal electric fields of fluctuational origin cause\nfast drift velocities of electron orbit centers which affect probabilities of\ninter-subband scattering and the photoconductivity. For the electron system\nformed on the liquid helium surface, internal forces are shown to suppress the\namplitude of magneto-oscillations, and change positions of magnetoconductivity\nminima which evolve in zero-resistance states for high radiation power."
    },
    {
        "anchor": "Coupling Tension and Shear for Highly Sensitive Graphene-Based Strain\n  Sensors: We report, based on its variation in electronic transport to coupled tension\nand shear deformation, a highly sensitive graphene-based strain sensor\nconsisting of an armchair graphene nanoribbon (AGNR) between metallic contacts.\nAs the nominal strain at any direction increases from 2.5 to 10%, the\nconductance decreases, particularly when the system changes from the\nelectrically neutral region. At finite bias voltage, both the raw conductance\nand the relative proportion of the conductance depends smoothly on the gate\nvoltage with negligible fluctuations, which is in contrast to that of pristine\ngraphene. Specifically, when the nominal strain is 10% and the angle varies\nfrom 0 degree to 90 degree, the relative proportion of the conductance changes\nfrom 60 to 90%.",
        "positive": "Controlling supercurrents and their spatial distribution in ferromagnets: Spin-triplet Cooper pairs induced in ferromagnets form the centrepiece of the\nemerging field of superconducting spintronics [1,2]. Usually the focus of\nresearch is on the spin polarization of the triplets, potentially enabling\nlow-dissipation magnetization switching and domain wall motion. However, the\nfundamental mechanism for generating triplet pairs [3,4] also permits control\nover a parameter which has not been addressed before, namely the spatial\ndistribution of the supercurrent. Here we demonstrate this control by tailoring\ndistinct supercurrent pathways in the ferromagnetic weak link of a Josephson\njunction. Combining micromagnetic simulations with three-dimensional critical\ncurrent calculations, based on the Usadel description of mesoscopic\nsuperconductivity [5], we designed a disk-shaped structure with a magnetic\nvortex, which induces two distinct supercurrent channels across the junction.\nThe design was successfully tested with superconducting quantum interferometry\n(SQI). Moreover, we show how the position of the pathways can be controlled by\nmoving the vortex with a magnetic field. This novel approach allows adaptable\nsupercurrent paths to be dynamically reconfigured to switch between different\nfunctionalities in the same device."
    },
    {
        "anchor": "$C_n$-symmetric higher-order topological crystalline insulators in\n  atomically thin transition-metal dichalcogenides: Based on first-principles calculations and symmetry analysis, we predict\natomically thin ($1-N$ layers) 2H group-VIB TMDs $MX_2$ ($M$ = Mo, W; $X$ = S,\nSe, Te) are large-gap higher-order topological crystalline insulators protected\nby $C_3$ rotation symmetry. We explicitly demonstrate the nontrivial\ntopological indices and existence of the hallmark corner states with quantized\nfractional charge for these familiar TMDs with large bulk optical band gaps\n($1.64-1.95$ eV for the monolayers), which would facilitate the experimental\ndetection by STM. We find that the well-defined corner states exist in the\ntriangular finite-size flakes with armchair edges of the atomically thin ($1-N$\nlayers) 2H group-VIB TMDs, and the corresponding quantized fractional charge is\nthe number of layers $N$ divided by 3 modulo integers, which will simply double\nincluding spin degree of freedom.",
        "positive": "First-principles calculations of phonon transport across a vacuum gap: Phonon transport across a vacuum gap separating intrinsic silicon crystals is\npredicted via the atomistic Green's function method combined with\nfirst-principles calculations of all interatomic force constants. The overlap\nof electron wave functions in the vacuum gap generates weak covalent\ninteraction between the silicon surfaces, thus creating a pathway for phonons.\nPhonon transport, dominated by acoustic modes, exceeds near-field radiation for\nvacuum gaps smaller than ~ 1 nm. The first-principles-based approach proposed\nin this work is critical to accurately quantify the contribution of phonon\ntransport to heat transfer in the extreme near field."
    },
    {
        "anchor": "Nonlinear light mixing by graphene plasmons: Graphene is known to possess strong optical nonlinearity. Its nonlinear\nresponse can be further enhanced by graphene plasmons. Here, we report a novel\nnonlinear electro-absorption effect observed in nanostructured graphene due to\nexcitation of graphene plasmons. We experimentally detect and theoretically\nexplain enhanced nonlinear mixing of near-infrared and mid-infrared light in\narrays of graphene nanoribbons. Strong compression of light by graphene\nplasmons implies that the effect is non-local in nature and orders of magnitude\nlarger than the conventional local graphene nonlinearity. The effect can be\nused in variety of applications including nonlinear light modulators, light\nmultiplexors, light logic, and sensing devices.",
        "positive": "Collective states of non-abelian quasiparticles in a magnetic field: Motivated by the physics of the Moore-Read \\nu = 1/2 state away from\nhalf-filling, we investigate collective states of non-abelian e/4\nquasiparticles in a magnetic field. We consider two types of collective states:\nincompressible liquids and Wigner crystals. In the incompressible liquid case,\nwe construct a natural series of states which can be thought of as a\nnon-abelian generalization of the Laughlin states. These states are associated\nwith a series of hierarchical states derived from the Moore-Read state - the\nsimplest of which occur at filling fraction 8/17 and 7/13. Interestingly, we\nfind that the hierarchical states are abelian even though their parent state is\nnon-abelian. In the Wigner crystal case, we construct two candidate states. We\nfind that they, too, are abelian - in agreement with previous analysis."
    },
    {
        "anchor": "Entropic uncertainty relations and topological-band insulator\n  transitions in 2D gapped Dirac materials: Uncertainty relations are studied for a characterization of topological-band\ninsulator transitions in 2D gapped Dirac materials isostructural with graphene.\nWe show that the relative or Kullback-Leibler entropy in position and momentum\nspaces, and the standard variance-based uncertainty relation, give sharp\nsignatures of topological phase transitions in these systems.",
        "positive": "Phase diagrams of disordered Weyl semimetals: Weyl semimetals are gapless quasi-topological materials with a set of\nisolated nodal points forming their Fermi surface. They manifest their\nquasi-topological character in a series of topological electromagnetic\nresponses including the anomalous Hall effect. Here we study the effect of\ndisorder on Weyl semimetals while monitoring both their nodal/semi-metallic and\ntopological properties through computations of the localization length and the\nHall conductivity. We examine three different lattice tight-binding models\nwhich realize the Weyl semimetal in part of their phase diagram and look for\nuniversal features that are common to all of the models, and interesting\ndistinguishing features of each model. We present detailed phase diagrams of\nthese models for large system sizes and we find that weak disorder preserves\nthe nodal points up to the diffusive limit, but does affect the Hall\nconductivity. We show that the trend of the Hall conductivity is consistent\nwith an effective picture in which disorder causes the Weyl nodes move within\nthe Brillouin zone along a specific direction that depends deterministically on\nthe properties of the model and the neighboring phases to the Weyl semimetal\nphase. We also uncover an unusual (non-quantized) anomalous Hall insulator\nphase which can only exist in the presence of disorder."
    },
    {
        "anchor": "Meron configurations in easy-plane chiral magnets: We demonstrate the existence and study in detail the features of chiral\nbimerons which are static solutions in an easy-plane magnet with the\nDzyaloshinskii-Moriya (DM) interaction. These are skyrmionic textures with an\ninteger topological charge and they present essential analogies to the meron\nconfigurations introduced in the context of quark confinement in the O(3)\nnonlinear sigma-model. We employ a Moebius transformation to show that, for\nweak chirality, bimeron configurations approach Belavin-Polyakov (BP) solutions\ncharacterized by tightly bound vortex and antivortex parts of the same size.\nStronger chirality induces different vortex and antivortex sizes and also a\ndetachment of merons, suggesting the possibility for a topological phase\ntransition. Exploiting the fact that bimerons of opposite topological charges\nmay exist in the same material, we demonstrate numerically a mechanism to\ngenerate meron pairs.",
        "positive": "Theory of microwave spectroscopy of Andreev bound states with a\n  Josephson junction: We present a microscopic theory for the current through a tunnel Josephson\njunction coupled to a non-linear environment, which consists of an Andreev\ntwo-level system coupled to a harmonic oscillator. It models a recent\nexperiment [Bretheau, Girit, Pothier, Esteve, and Urbina, Nature (London) 499,\n312 (2013)] on photon spectroscopy of Andreev bound states in a superconducting\natomic-size contact. We find the eigenenergies and eigenstates of the\nenvironment and derive the current through the junction due to inelastic Cooper\npair tunneling. The current-voltage characteristic reveals the transitions\nbetween the Andreev bound states, the excitation of the harmonic mode that\nhybridizes with the Andreev bound states, as well as multi-photon processes.\nThe calculated spectra are in fair agreement with the experimental data."
    },
    {
        "anchor": "AC-Conductance through an Interacting Quantum Dot: We investigate the linear ac-conductance for tunneling through an arbitrary\ninteracting quantum dot in the presence of a finite dc-bias. In analogy to the\nwell-known Meir-Wingreen formula for the dc case, we are able to derive a\ngeneral formula for the ac-conductance. It can be expressed entirely in terms\nof local correlations on the quantum dot, in the form of a Keldysh block\ndiagram with four external legs. We illustrate the use of this formula as a\nstarting point for diagrammatic calculations by considering the ac-conductance\nof the noninteracting resonant level model and deriving the result for the\nlowest order of electron-phonon coupling. We show how known results are\nrecovered in the appropriate limits.",
        "positive": "Optimal in situ electromechanical sensing of molecular species: We investigate protocols for optimal molecular detection with\nelectromechanical nanoscale sensors in ambient conditions. Our models are\nrepresentative of suspended graphene nanoribbons, which due to their\npiezoelectric and electronic properties, provide responsive and versatile\nsensors. In particular, we analytically account for the corrections in the\nelectronic transmission function and signal-to-noise ratio originating in\nenvironmental perturbations, such as thermal fluctuations and solvation\neffects. We also investigate the role of the sampling time in the current\nstatistics. As a result, we formulate a protocol for optimal sensing based on\nthe modulation of the Fermi level at fixed bias, and provide approximate forms\nfor the current, linear susceptibility, and current fluctuations. We show how\nthe algebraic tails in the thermally broadened transmission function affect the\nbehavior of the signal-to-noise ratio and optimal sensing. These results\nprovide further insights into the operation of graphene deflectometers and\nother techniques for electromechanical sensing."
    },
    {
        "anchor": "Bias dependence of magnetic exchange interactions: application to\n  interlayer exchange coupling in spin valves: We study how a bias voltage changes magnetic exchange interactions. We derive\na general expression for magnetic exchange interactions for systems coupled to\nreservoirs under a bias potential, and apply it to spin valves. We find that\nfor metallic systems, the interlayer exchange coupling shows a weak,\noscillatory dependence on the bias potential. For tunneling systems, we find a\nquadratic dependence on the bias potential, and derive an approximate\nexpression for this bias dependence for a toy model. We give general conditions\nfor when the interlayer exchange coupling is a quadratic function of bias\npotential.",
        "positive": "Difference between angular momentum and pseudoangular momentum: In condensed matter systems it is necessary to distinguish between the\nmomentum of the constituents of the system and the pseudomomentum of\nquasiparticles. The same distinction is also valid for angular momentum and\npseudoangular momentum. Based on Noether's theorem, we demonstrate that the\nrecently discussed orbital angular momenta of phonons and magnons are\npseudoangular momenta. This conceptual difference is important for a proper\nunderstanding of the transfer of angular momentum in condensed matter systems,\nespecially in spintronics applications."
    },
    {
        "anchor": "Correlation Dynamics and Enhanced Signals for Serial DNA Sequencing: Nanopore based sequencing has demonstrated significant potential for the\ndevelopment of fast, accurate, and cost-efficient fingerprinting techniques for\nnext generation molecular detection and sequencing. We propose a specific\nmulti-layered graphene-based nanopore device architecture for the recognition\nof single DNA bases. Molecular detection and analysis can be accomplished\nthrough the detection of transverse currents as the molecule or DNA base\ntranslocates through the nanopore. To increase the overall signal-to-noise\nratio and the accuracy, we implement a new \"multi-point cross-correlation\"\ntechnique for identification of DNA bases or other molecules on the molecular\nlevel. We demonstrate that the cross-correlations between each nanopore will\ngreatly enhance the transverse current signal for each molecule. We implement\nfirst-principles transport calculations for DNA bases surveyed across a\nmulti-layered graphene nanopore system to illustrate the advantages of proposed\ngeometry. A time-series analysis of the cross-correlation functions illustrates\nthe potential of this method for enhancing the signal-to-noise ratio. This work\nconstitutes a significant step forward in facilitating fingerprinting of single\nbiomolecules using solid state technology.",
        "positive": "Excitons in square quantum wells: microscopic modeling and experiment: The binding energy and the corresponding wave function of excitons in\nGaAs-based finite square quantum wells (QWs) are calculated by the direct\nnumerical solution of the three-dimensional Schroedinger equation. The precise\nresults for the lowest exciton state are obtained by the Hamiltonian\ndiscretization using the high-order finite-difference scheme. The microscopic\ncalculations are compared with the results obtained by the standard variational\napproach. The exciton binding energies found by two methods coincide within 0.1\nmeV for the wide range of QW widths. The radiative decay rate is calculated for\nQWs of various widths using the exciton wave functions obtained by direct and\nvariational methods. The radiative decay rates are confronted with the\nexperimental data measured for high-quality GaAs/AlGaAs and InGaAs/GaAs QW\nheterostructures grown by molecular beam epitaxy. The calculated and measured\nvalues are in good agreement, though slight differences with earlier\ncalculations of the radiative decay rate are observed."
    },
    {
        "anchor": "A fast, sensitive, room-temperature graphene nanomechanical bolometer: Bolometers are a powerful and vital means of detecting light in the IR to THz\nfrequencies, and they have been adopted for a range of uses from astronomical\nobservation to thermal imaging. As uses diversify, there is an increasing\ndemand for faster, more sensitive room-temperature bolometers. To this end,\ngraphene has generated interest because of its miniscule heat capacity and its\nintrinsic ultra-broadband absorption, properties that would allow it to quickly\ndetect low levels of light of nearly any wavelength. Yet, graphene has\ndisappointed its expectations in traditional electrical bolometry at room\ntemperature, because of its weakly temperature-dependent resistivity and\nexceptionally high thermal conductivity. Here, we overcome these challenges\nwith a new approach that detects light by tracking the resonance frequency of a\ngraphene nanomechanical resonator. The absorbed light heats up and thermally\ntensions the resonator, thereby changing its frequency. Using this approach, we\nachieve a room-temperature noise-equivalent power of 7 pW/Hz^1/2, a value 100\ntimes more sensitive than electrical graphene bolometers, and speeds (1.3 MHz)\nthat greatly surpass state-of-the-art microbolometers.",
        "positive": "Kondo effect in coupled quantum dots under magnetic fields: The Kondo effect in coupled quantum dots is investigated theoretically under\nmagnetic fields. We show that the magnetoconductance (MC) illustrates peak\nstructures of the Kondo resonant spectra. When the dot-dot tunneling coupling\n$V_C$ is smaller than the dot-lead coupling $\\Delta$ (level broadening), the\nKondo resonant levels appear at the Fermi level ($E_F$). The Zeeman splitting\nof the levels weakens the Kondo effect, which results in a negative MC. When\n$V_{C}$ is larger than $\\Delta$, the Kondo resonances form bonding and\nanti-bonding levels, located below and above $E_F$, respectively. We observe a\npositive MC since the Zeeman splitting increases the overlap between the levels\nat $E_F$. In the presence of the antiferromagnetic spin coupling between the\ndots, the sign of MC can change as a function of the gate voltage."
    },
    {
        "anchor": "Nonlinear electromagnetic response of few-layer graphene: A\n  nonperturbative description: Nonperturbative approach based on exact solution of Boltzmann kinetic\nequation in the relaxation time approximation is developed for the study of\nnonlinear response of electron-doped few-layer graphene to a high-frequency\nelectromagnetic field. It is shown that nonperturbative approach can be applied\nto a two-dimensional conductor with an arbitrary isotropic spectrum of\ncarriers.",
        "positive": "One-dimensional flat bands and Dirac cones in narrow zigzag dice lattice\n  ribbons: We show that four narrow zigzag dice lattice ribbons, which have the minimal\nwidths among their separate categories, constitute a unique collection of\nsystems to study physics related to one-dimensional Dirac cones and flat bands.\nIn zero magnetic field, all three combinations, including only Dirac cones,\nonly flat bands, coexisting Dirac cones and flat bands, are realized in the\nlow-energy band structures of one or two of the four ribbons. In particular, we\nidentify flat bands and Dirac cones corresponding to the edge states of wide\nribbons. In a perpendicular magnetic field that gives half a flux quantum per\nelementary rhombus, two of the four minimal ribbons have fully pinched\nspectrum, and dynamical evolutions from initially localized wave packets always\nlead to compact Aharonov-Bohm (AB) cages. The experimental realizations of\nthese narrow zigzag dice lattice ribbons, and the opportunities of exploring\nnovel single-body and many-body physics therein are discussed."
    },
    {
        "anchor": "Pairing and persistent currents - the role of the far levels: We calculate the orbital magnetic response to Aharonov Bohm flux of\ndisordered metallic rings with attractive pairing interaction. We consider the\nreduced BCS model, and obtain the result as an expansion of its exact solution\nto first order in the interaction. We emphasize the connection between the\nlarge magnetic response and the finite occupation of high energy levels in the\nmany-body ground state of the ring.",
        "positive": "Topologically protected elastic waves in one-dimensional phononic\n  crystals of continuous media: We report the design of silica-based 1D phononic crystals (PnCs) with\ntopologically distinct complete phononic bandgaps (PnBGs) and the observation\nof a topologically protected state of elastic waves at their interface. By\nchoosing different structural parameters of unit cells, two PnCs can possess a\ncommon PnBG with different topological nature. At the interface between the two\nPnCs, a topological interface mode with a quality factor of ~5,650 is observed\nin the PnBG. Spatial confinement of the interface mode is also confirmed by\nusing photoelastic imaging technique. Such topologically protected elastic\nstates are potentially applicable for constructing novel phononic devices."
    },
    {
        "anchor": "Experimental evidence and control of the bulk-mediated intersurface\n  coupling in topological insulator Bi2Te2Se nanoribbons: Nearly a decade after the discovery of topological insulators (TIs), the\nimportant task of identifying and characterizing their topological surface\nstates through electrical transport experiments remains incomplete. The\ninterpretation of these experiments is made difficult by the presence of\nresidual bulk carriers and their coupling to surface states, which is not yet\nwell understood. In this work, we present the first evidence for the existence\nand control of bulk-surface coupling in Bi2Te2Se nanoribbons, which are\npromising platforms for future TI-based devices. Our magnetoresistance\nmeasurements reveal that the number of coherent channels contributing to\nquantum interference in the nanoribbons changes abruptly when the film\nthickness exceeds the bulk phase relaxation length. We interpret this\nobservation as an evidence for bulk-mediated coupling between metallic states\nlocated on opposite surfaces. This hypothesis is supported by additional\nmagnetoresistance measurements conducted under a set of gate voltages and in a\nparallel magnetic field, the latter of which alters the intersurface coupling\nin a controllable way.",
        "positive": "Retrieving qubit information despite decoherence: The time evolution of a qubit, consisting of two single-level quantum dots,\nis studied in the presence of telegraph noise. The dots are connected by two\ntunneling paths, with an Aharonov-Bohm flux enclosed between them. Under\nspecial symmetry conditions, which can be achieved by tuning gate voltages,\nthere develops partial decoherence: at long times, the off-diagonal element of\nthe reduced density matrix (in the basis of the two dot states) approaches a\nnon-zero value, generating a circulating current around the loop. The flux\ndependence of this current contains full information on the initial quantum\nstate of the qubit, even at infinite time. Small deviations from this symmetry\nyield a very slow exponential decay towards the fully-decoherent limit.\nHowever, the amplitudes of this decay also contain the full information on the\ninitial qubit state, measurable either via the current or via the occupations\nof the qubit dots."
    },
    {
        "anchor": "Optical pumping of charged excitons in unintentionally doped InAs\n  quantum dots: As an alternative to commonly used electrical methods, we have investigated\nthe optical pumping of charged exciton complexes addressing impurity related\ntransitions with photons of the appropriate energy. Under these conditions, we\ndemonstrate that the pumping fidelity can be very high while still maintaining\na switching behavior between the different excitonic species. This mechanism\nhas been investigated for single quantum dots of different size present in the\nsame sample and compared with the direct injection of spectator electrons from\nnearby donors.",
        "positive": "STM observation of a box-shaped graphene nanostructure appeared after\n  mechanical cleavage of pyrolytic graphite: A description is given of a three-dimensional box-shaped graphene (BSG)\nnanostructure formed/uncovered by mechanical cleavage of highly oriented\npyrolytic graphite (HOPG). The discovered nanostructure is a multilayer system\nof parallel hollow channels located along the surface and having quadrangular\ncross-section. The thickness of the channel walls/facets is approximately equal\nto 1 nm. The typical width of channel facets makes about 25 nm, the channel\nlength is 390 nm and more. The investigation of the found nanostructure by\nmeans of a scanning tunneling microscope (STM) allows us to draw a conclusion\nthat it is possible to make spatial constructions of graphene similar to the\ndiscovered one by mechanical compression, bending, splitting, and shifting\ngraphite surface layers. The distinctive features of such constructions are the\nfollowing: simplicity of the preparation method, small contact area between\ngraphene planes and a substrate, large surface area, nanometer cross-sectional\nsizes of the channels, large aspect ratio. Potential fields of application\ninclude: ultra-sensitive detectors, high-performance catalytic cells,\nnanochannels for DNA manipulation, nanomechanical resonators, electron\nmultiplication channels, high-capacity sorbents for hydrogen storage."
    },
    {
        "anchor": "Anisotropic Zeeman splitting in ballistic one-dimensional hole systems: We have studied the effect of an in-plane magnetic field B on a\none-dimensional hole system in the ballistic regime created by surface gate\nconfinement. We observed clearly the lifting of the spin degeneracy due to the\nZeeman effect on the one dimensional subbands for B applied parallel to the\nchannel. In contrast, no Zeeman splitting is detected for B applied\nperpendicular to the channel, revealing an extreme anisotropy of the effective\nLande g-factor g*. We demonstrate that this anisotropy is a direct consequence\nof the one-dimensional confinement on a system with strong spin-orbit coupling.",
        "positive": "Duality Near Quantum Hall Transitions: A recent experiment by Shahar et al, on the phase transitions between quantum\nHall states and the insulator, found that the current-voltage characteristics\nin the two phases are related by symmetry. It was suggested in this work that\nthis is evidence for charge-flux duality near quantum Hall transitions. Here we\nprovide details of this analysis. (Appearances notwithstanding, this is a\ntheoretical paper.)"
    },
    {
        "anchor": "Electronic resonance states in metallic nanowires during the breaking\n  process simulated with the ultimate jellium model: We investigate the elongation and breaking process of metallic nanowires\nusing the ultimate jellium model in self-consistent density-functional\ncalculations of the electron structure. In this model the positive background\ncharge deforms to follow the electron density and the energy minimization\ndetermines the shape of the system. However, we restrict the shape of the wires\nby assuming rotational invariance about the wire axis. First we study the\nstability of infinite wires and show that the quantum mechanical\nshell-structure stabilizes the uniform cylindrical geometry at given magic\nradii. Next, we focus on finite nanowires supported by leads modeled by\nfreezing the shape of a uniform wire outside the constriction volume. We\ncalculate the conductance during the elongation process using the adiabatic\napproximation and the WKB transmission formula. We also observe the correlated\noscillations of the elongation force. In different stages of the elongation\nprocess two kinds of electronic structures appear: one with extended states\nthroughout the wire and one with an atom-cluster like unit in the constriction\nand with well localized states. We discuss the origin of these structures.",
        "positive": "Ultra-Low Threshold Monolayer Semiconductor Nanocavity Lasers: Engineering the electromagnetic environment of a nanoscale light emitter by a\nphotonic cavity can significantly enhance its spontaneous emission rate through\ncavity quantum electrodynamics in the Purcell regime. This effect can greatly\nreduce the lasing threshold of the emitter, providing the ultimate\nlow-threshold laser system with small footprint, low power consumption and\nultrafast modulation. A state-of-the-art ultra-low threshold nanolaser has been\nsuccessfully developed though embedding quantum dots into photonic crystal\ncavity (PhCC). However, several core challenges impede the practical\napplications of this architecture, including the random positions and\ncompositional fluctuations of the dots, extreme difficulty in current\ninjection, and lack of compatibility with electronic circuits. Here, we report\na new strategy to lase, where atomically thin crystalline semiconductor, i.e.,\na tungsten-diselenide (WSe2) monolayer, is nondestructively and\ndeterministically introduced as a gain medium at the surface of a\npre-fabricated PhCC. A new type of continuous-wave nanolaser operating in the\nvisible regime is achieved with an optical pumping threshold as low as 27 nW at\n130 K, similar to the value achieved in quantum dot PhCC lasers. The key to the\nlasing action lies in the monolayer nature of the gain medium, which confines\ndirect-gap excitons to within 1 nm of the PhCC surface. The surface-gain\ngeometry allows unprecedented accessibilities to multi-functionalize the gain,\nenabling electrically pumped operation. Our scheme is scalable and compatible\nwith integrated photonics for on-chip optical communication technologies."
    },
    {
        "anchor": "Gate-activated photoresponse in a graphene p-n junction: We study photodetection in graphene near a local electrostatic gate, which\nenables active control of the potential landscape and carrier polarity. We find\nthat a strong photoresponse only appears when and where a p-n junction is\nformed, allowing on-off control of photodetection. Photocurrents generated near\np-n junctions do not require biasing and can be realized using submicron gates.\nLocally modulated photoresponse enables a new range of applications for\ngraphene-based photodetectors including, for example, pixilated infrared\nimaging with control of response on subwavelength dimensions.",
        "positive": "Entanglement dynamics of a superconducting phase qubit coupled to a\n  two-level system: We report the observation and quantitative characterization of driven and\nspontaneous oscillations of quantum entanglement, as measured by concurrence,\nin a bipartite system consisting of a macroscopic Josephson phase qubit coupled\nto a microscopic two-level system. The data clearly show the behavior of\nentanglement dynamics such as sudden death and revival, and the effect of\ndecoherence and ac driving on entanglement."
    },
    {
        "anchor": "Detection of Zak phases and topological invariants in a chiral quantum\n  walk of twisted photons: Topological insulators are fascinating states of matter exhibiting protected\nedge states and robust quantized features in their bulk. Here, we propose and\nvalidate experimentally a method to detect topological properties in the bulk\nof one-dimensional chiral systems. We first introduce the mean chiral\ndisplacement, and we show that it rapidly approaches a multiple of the Zak\nphase in the long time limit. Then we measure the Zak phase in a photonic\nquantum walk, by direct observation of the mean chiral displacement in its\nbulk. Next, we measure the Zak phase in an alternative, inequivalent timeframe,\nand combine the two windings to characterize the full phase diagram of this\nFloquet system. Finally, we prove the robustness of the measure by introducing\ndynamical disorder in the system. This detection method is extremely general,\nas it can be applied to all one-dimensional platforms simulating static or\nFloquet chiral systems.",
        "positive": "Tilt Induced Localization and Delocalization in the Second Landau Level: We have investigated the behavior of electronic phases of the second Landau\nlevel under tilted magnetic fields. The fractional quantum Hall liquids at\n$\\nu=$2+1/5 and 2+4/5 and the solid phases at $\\nu=$2.30, 2.44, 2.57, and 2.70\nare quickly destroyed with tilt. This behavior can be interpreted as a tilt\ndriven localization of the 2+1/5 and 2+4/5 fractional quantum Hall liquids and\na delocalization through melting of solid phases in the top Landau level,\nrespectively. The evolution towards the classical Hall gas of the solid phases\nis suggestive of antiferromagnetic ordering."
    },
    {
        "anchor": "Intermediate band formation and intraband absorption for electrons in an\n  inhomogeneous chain of quantum dots: We study the electron states of a chain of non-identical, vertically stacked\nquantum dots (QDs). We discuss how the pseudo-band formed of the ground states\nconfined in the QDs disintegrates upon increasing the inhomogeneity of the\nelectron energies and analyze the impact of localization on the intraband\nabsorption from the pseudo-band to extended (bulk) states. We describe also the\ndependence of the intraband absorption spectrum on the QD size.",
        "positive": "Mechanically induced spin resonance in a carbon nanotube: The electron spin is a promising qubit candidate for quantum computation and\nquantum information. Here we propose and analyze a mechanically-induced single\nelectron spin resonance, which amounts to a rotation of the spin about the\n$x$-axis in a suspended carbon nanotube. The effect is based on the coupling\nbetween the spin and the mechanical degree of freedom due to the intrinsic\ncurvature-induced spin-orbit coupling. A rotation about the $z$-axis is\nobtained by the off-resonant external electric driving field. Arbitrary-angle\nrotations of the single electron spin about any axis in the $x$-$z$ plane can\nbe obtained with a single operation by varying the frequency and the strength\nof the external electric driving field. With multiple steps combining the\nrotations about the $x$- and $z$-axes, arbitrary-angle rotations about\narbitrary axes can be constructed, which implies that any single-qubit gate of\nthe electron spin qubit can be performed. We simulate the system numerically\nusing a master equation with realistic parameters."
    },
    {
        "anchor": "Nanowire design by magnetic collection of Fe, Ni and/or FeNi-alloy\n  nanoparticles: A method for growing nanoparticles with different elemental compositions\nsimply by changing pulsing parameters in a power supply is demonstrated. The\ntechnique is based on high power pulsed hollow cathode sputtering, and the\ndifference in particle composition ranges from pure Fe and Ni, to fully alloyed\nFeNi particles. Several pulses, or bursts, from a hollow cathode are needed in\norder to grow a nanoparticle using high power pulses. With this in mind, we\ndevised a setup with two hollow cathodes of different material, Fe and Ni,\nsituated in the vicinity of each other. By using two power supplies and a\nsynchronization unit, the number and size of pulses of each element into the\ngrowth regime of the nanoparticles is controlled, and a tunable mixture of ions\nof the two elements is ensured. We here show that the two-target high power\nhollow cathode sputtering unit can be a powerful tool for rapid prototyping of\nmore advanced, customized, nanoparticles, which can be of great importance for\nnumerous applications.",
        "positive": "Transverse currents in spin transistors: In many systems, planar Hall effect wherein transverse signal appears in\nresponse to longitudinal stimulus is rooted in spin-orbit coupling. A spin\ntransistor put forward by Datta and Das on the other hand consists of\nferromagnetic leads connected to spin-orbit coupled central region and its\nconductance can be controlled by tuning the strength of spin-orbit coupling. We\nfind that transverse currents also appear in Datta-Das transistors made by\nconnecting two two-dimensional ferromagnetic reservoirs to a central spin-orbit\ncoupled two-dimensional electron gas. We find that the spin transistor exhibits\na nonzero transverse conductivity which depends on the direction of\npolarization in ferromagnets and the location where it is measured. We study\nthe conductivities for the system with finite and infinite widths. The\nconductivities exhibit Fabry-P\\'erot type oscillations as the length of the\nspin-orbit coupled regions is varied. Interestingly, even in the limit when\nlongitudinal conductivity is made zero by cutting off the junction between the\ncentral spin-orbit coupled region and the ferromagnetic lead on one side\n(right), the transverse conductivities remain nonzero in the regions that are\non the left side of the cut-off junction."
    },
    {
        "anchor": "Giant Tunable Mechanical Nonlinearity in Graphene-Silicon Nitride Hybrid\n  Resonator: High quality factor mechanical resonators have shown great promise in\ndeveloping classical or quantum technologies. Simultaneously, progress has been\nmade in developing controlled mechanical nonlinearity. Here we combine these\ntwo directions of progress in a single platform consisting of coupled Silicon\nNitride (SiNx) and graphene mechanical resonators. We show that nonlinear\nresponse can be induced on a large area SiNx resonator mode and can be\nefficiently controlled by coupling it to a gate-tunable, freely suspended\ngraphene mode. The induced nonlinear response of the hybrid modes, as measured\non the SiNx resonator surface is giant, with one of the highest measured\nDuffing constants. We observe a novel phononic frequency comb which we use as\nan alternate validation of the measured values, along with numerical\nsimulations which are in overall agreement with measurements.",
        "positive": "Two-dimensional platform for networks of Majorana bound states: We model theoretically a two-dimensional electron gas (2DEG) covered by a\nsuperconductor and demonstrate that topological superconducting channels are\nformed when stripes of the superconducting layer are removed. As a consequence,\nMajorana bound states (MBS) are created at the ends of the stripes. We\ncalculate the topological invariant and energy gap of a single stripe, using\nrealistic values for an InAs 2DEG proximitized by an epitaxial Al layer. We\nshow that the topological gap is enhanced when the structure is made\nasymmetric. This can be achieved by either imposing a phase difference (by\ndriving a supercurrent or using a magnetic-flux loop) over the strip or by\nreplacing one superconductor by a metallic gate. Both strategies also enable\ncontrol over the MBS splitting, thereby facilitating braiding and readout\nschemes based on controlled fusion of MBS. Finally, we outline how a network of\nMajorana stripes can be designed."
    },
    {
        "anchor": "THz parametric gain in semiconductor superlattices in the absence of\n  electric domains: We theoretically show that conditions for THz gain and conditions for\nformation of destructive electric domains in semiconductor superlattices are\nfairly different in the case of parametric generation and amplification. Action\nof an unbiased high-frequency electric field on a superlattice causes a\nperiodic variation of energy and effective mass of miniband electrons. This\nparametric effect can result in a significant gain at some even harmonic of the\npump frequency without formation of electric domains and corruption from pump\nharmonics.",
        "positive": "Wave Packet Dynamics, Ergodicity, and Localization in Quasiperiodic\n  Chains: In this paper, we report results for the wave packet dynamics in a class of\nquasiperiodic chains consisting of two types of weakly coupled clusters. The\ndynamics are studied by means of the return probability and the mean square\ndisplacement. The wave packets show anomalous diffusion in a stepwise process\nof fast expansion followed by time intervals of confined wave packet width.\nApplying perturbation theory, where the coupling parameter v is treated as\nperturbation, the properties of the eigenstates of the system are investigated\nand related to the structure of the chains. The results show the appearance of\nnon-localized states only in sufficiently high orders of the perturbation\nexpansions. Further, we compare these results to the exact solutions obtained\nby numerical diagonalization. This shows that eigenstates spread across the\nentire chain for v>0, while in the limit v->0 ergodicity is broken and\neigenstates only spread across clusters of the same type, in contradistinction\nto trivial localization for v=0. Caused by this ergodicity breaking, the wave\npacket dynamics change significantly in the presence of an impurity offering\nthe possibility to control its long-term dynamics."
    },
    {
        "anchor": "Ultralow-noise terahertz detection by p-n junctions in gapped bilayer\n  graphene: Graphene shows a strong promise for detection of terahertz (THz) radiation\ndue to its high carrier mobility, compatibility with on-chip waveguides and\ntransistors, and small heat capacitance. At the same time, weak reaction of\ngraphene's physical properties on the detected radiation can be traced down to\nthe absence of band gap. Here, we study the effect of electrically-induced band\ngap on THz detection in graphene bilayer with split-gate p-n junction. We show\nthat gap induction leads to simultaneous increase in current and voltage\nresponsivities. At operating temperatures of ~25 K, the responsivity at 20 meV\nband gap is from 3 to 20 times larger than that in the gapless state. The\nmaximum voltage responsivity of our devices at 0.13 THz illumination exceeds 50\nkV/W, while the noise equivalent power falls down to 36 fW/Hz^0.5. These values\nset new records for semiconductor-based cryogenic terahertz detectors, and pave\nthe way for efficient and fast terahertz detection.",
        "positive": "Probing the potential landscape inside a two-dimensional electron-gas: We report direct observations of the scattering potentials in a\ntwo-dimensional electron-gas using electron-beam diffaction-experiments. The\ndiffracting objects are local density-fluctuations caused by the spatial and\ncharge-state distribution of the donors in the GaAs-(Al,Ga)As heterostructures.\nThe scatterers can be manipulated externally by sample illumination, or by\ncooling the sample down under depleted conditions."
    },
    {
        "anchor": "Giant microwave photoresistance of two-dimensional electron gas: We measure microwave frequency (4-40 GHz) photoresistance at low magnetic\nfield B, in high mobility 2D electron gas samples, excited by signals applied\nto a transmission line fabricated on the sample surface. Oscillatory\nphotoresistance vs B is observed. For excitation at the cyclotron resonance\nfrequency, we find an unprecedented, giant relative photoresistance (\\Delta\nR)/R of up to 250 percent. The photoresistance is apparently proportional to\nthe square root of applied power, and disappears as the temperature is\nincreased.",
        "positive": "Oscillations of the magnetic polarization in a Kondo impurity at finite\n  magnetic fields: The electronic properties of a Kondo impurity are investigated in a magnetic\nfield using linear response theory. The distribution of electrical charge and\nmagnetic polarization are calculated in real space. The (small) magnetic field\ndoes not change the charge distribution. However, it unmasks the Kondo cloud.\nThe (equal) weight of the d-electron components with their magnetic moment up\nand down is shifted and the compensating s-electron clouds don't cancel any\nlonger (a requirement for an experimental detection of the Kondo cloud). In\naddition to the net magnetic polarization of the conduction electrons an\noscillating magnetic polarization with a period of half the Fermi wave length\nis observed. However, this oscillating magnetic polarization does not show the\nlong range behavior of Rudermann-Kittel-Kasuya-Yosida oscillations because the\noscillations don't extend beyond the Kondo radius. They represent an internal\nelectronic structure of the Kondo impurity in a magnetic field. PACS: 75.20.Hr,\n71.23.An, 71.27.+a"
    },
    {
        "anchor": "Effect of Interlayer Shear to Graphene Resonators: Graphene nanostrips with single or a few layers can be made into bending\nresonators with extremely high sensitivity to environment changes. In this work\nwe study the effect of interlayer shear on resonant frequencies f of graphene\nnanostrips, via both molecular dynamics (MD) simulation and elastic model\nanalysis incorporating interlayer shear. Contrary to the classical thin beam\ntheory prediction f~nl^-2 (l is beam length and n layer number), MD simulation\nresults reveal very different dependences, f~l^-1.36 and f - fmono~(n-1)/n\n(fmono is frequency of the monolayer beam). Interlayer shear modulus of\nmultilayer graphene strips is much smaller than their intralayer Young's\nmodulus, and the weak interlayer interaction can not maintain the registry\nbetween the carbon atoms in adjacent layers. Large shear deformation occurs\nduring vibration of multilayer graphene nano-strips. Therefore we propose a\nmulti-beam shear model (MBSM) with the interlayer shear energy of multilayer\ngraphene nano-strips taken into account. It makes predictions consistent\nexcellently with direct MD simulations without any fitting parameter required.\nThe results are of importance for various applications of multi-layer graphene\nnano-strips, such as in nano-electromechanical devices including resonators,\nsensors and actuators, where interlayer shear has apparent impacts to\ndeformation, vibration, and energy dissipation processes.",
        "positive": "Spin relaxation rates in quasi-one-dimensional coupled quantum dots: We study theoretically the spin relaxation rate in quasi-one-dimensional\ncoupled double semiconductor quantum dots. We consider InSb and GaAs-based\nsystems in the presence of the Rashba spin-orbit interaction, which causes\nmixing of opposite-spin states, and allows phonon-mediated transitions between\nenergy eigenstates. Contributions from all phonon modes and coupling mechanisms\nin zincblende semiconductors are taken into account. The spin relaxation rate\nis shown to display a sharp, cusp-like maximum as function of the\ninterdot-barrier width, at a value of the width which can be controlled by an\nexternal magnetic field. This remarkable behavior is associated with the\nsymmetric-antisymmetric level splitting in the structure."
    },
    {
        "anchor": "Majorana corner modes in a high-temperature platform: We introduce two-dimensional topological insulators in proximity to\nhigh-temperature cuprate or iron-based superconductors as high-temperature\nplatforms of Majorana Kramers pairs of zero modes. The proximity-induced\npairing at the helical edge state of the topological insulator serves as a\nDirac mass, whose sign changes at the sample corner because of the pairing\nsymmetry of high-$T_c$ superconductors. This sign changing naturally creates at\neach corner a pair of Majorana zero modes protected by time-reversal symmetry.\nConceptually, this is a topologically trivial superconductor-based approach for\nMajorana zero modes. We provide quantitative criteria and suggest candidate\nmaterials for this proposal.",
        "positive": "Distortion of Wigner molecules : pair function approach: We considered a two dimensional three electron quantum dot in a magnetic\nfield in the Wigner limit. A unitary coordinate transformation decouples the\nHamiltonian (with Coulomb interaction between the electrons included) into a\nsum of three independent pair Hamiltonians. The eigen-solutions of the pair\nHamiltonian provide a spectrum of pair states. Each pair state defines the\ndistance of the two electrons involved in this state. In the ground state for\ngiven pair angular momentum $m$, this distance increases with increasing $|m|$.\nThe pair states have to be occupied under consideration of the Pauli exclusion\nprinciple, which differs from that for one-electron states and depends on the\ntotal spin $S$ and the total orbital angular momentum $M_L=\\sum m_i$ (sum over\nall pair angular momenta). We have shown that the three electrons in the ground\nstate of the Wigner molecule form an equilateral triangle (as might be\nexpected) only, if the state is a quartet ($S=3/2$) and the orbital angular\nmomentum is a magic quantum number ($M_L=3 m ; m=$ integer). Otherwise the\ntriangle in the ground state is isosceles. For $M_L=3 m+1$ one of the sides is\nlonger and for $M_L=3 m-1$ one of the sides is shorter than the other two."
    },
    {
        "anchor": "Effect of long-range interaction on graphene edge magnetism: It has been proposed that interactions lead to ferromagnetism on a zigzag\nedge of a graphene sheet. While not yet directly studied experimentally,\ndramatically improving techniques for making and studying clean zigzag edges\nmay soon make this possible. So far, most theoretical investigations of this\nclaim have been based on mean field theories or more exact calculations using\nthe Hubbard model. But long-range Coulomb interactions are unscreened in\ngraphene so it is important to consider their effects. We study rather general\nnon-local interactions, including of Coulomb $1/r$ form, using the technique of\nprojection to a strongly interacting edge Hamiltonian, valid at first order in\nthe interactions. The ground states as well as electron/hole and exciton\nexcitations are studied in this model. Our results indicate that ferromagnetism\nsurvives with unscreened Coulomb interactions.",
        "positive": "Tuning magnetic charge population and mobility in unidirectional array\n  of nanomagnets as a function of lattice parameters: Sets of nanomagnets are often utilized to mimic cellular automata in design\nof nanomagnetic logic devices or frustration and emergence of magnetic charges\nin artificial spin ice systems. in previous work we showed that unidirectional\narrangement of nanomagnets can behave as artificial spin ice, with frustration\narising from second neighbor dipolar interaction, and present good magnetic\ncharge mobility due to the low string tension among charges. Here, we present\nan experimental investigation of magnetic charge population and mobility in\nfunction of lateral and longitudinal distance among nanomagnets. Our results\ncorroborate partially the theoretical predictions, performed elsewhere by\nemergent interaction model, could be useful in nanomagnet logic devices design\nand brings new insights about the best design for magnetic charge ballistic\ntransport under low external magnetic field with magnetic charge mobility\ntunning for application in magnetricity."
    },
    {
        "anchor": "Electrical resistance associated with the scattering of optically\n  oriented electrons in n-GaAs: In a bulk GaAs crystal, an unusual magnetoresistance effect, which takes\nplace when a spin-polarized current flows through the sample, was detected.\nUnder conditions of optical pumping of electron spins, an external magnetic\nfield directed along the electric current and perpendicular to the oriented\nspins decreases the resistance of the material. The phenomenon is due to the\nspin-dependent scattering of electrons by neutral donors. It was found that the\nsign of the magnetoresistance does not depend on the sign of the exciting light\ncircular polarization, the effect is even with respect to the sign of the spin\npolarization of the carriers, which indicates a correlation between the spins\nof optically oriented free electrons and electrons localized on donors.",
        "positive": "Metallic coplanar resonators optimized for low-temperature measurements: Metallic coplanar microwave resonators are widely employed at room\ntemperature, but their low-temperature performance has received little\nattention so far. We characterize compact copper coplanar resonators with\nmultiple modes from 2.5 to 20 GHz at temperatures as low as 5 K. We investigate\nthe influence of center conductor width (20 to 100 {\\mu}m) and coupling gap\nsize (10 to 50 {\\mu}m), and we observe a strong increase of quality factor (Q)\nfor wider center conductors, reaching values up to 470. The magnetic-field\ndependence of the resonators is weak, with a maximum change in Q of 3.5% for an\napplied field of 7 T. This makes these metallic resonators well suitable for\nmagnetic resonance studies, as we document with electron spin resonance (ESR)\nmeasurements at multiple resonance frequencies."
    },
    {
        "anchor": "Influence of correlated impurities on conductivity of graphene sheets:\n  Time-dependent real-space Kubo approach: Exact numerical calculations of the conductivity of graphene sheets with\nrandom and correlated distributions of disorders have been performed using the\ntime-dependent real-space Kubo formalism. The disorder was modeled by the\nlong-range Gaussian potential describing screened charged impurities and by the\nshort-range potential describing neutral adatoms both in the weak and strong\nscattering regime. Our central result is that correlation in the spatial\ndistribution for the strong short-range scatterers and for the long-range\nGaussian potential do not lead to any enhancement of the conductivity in\ncomparison to the uncorrelated case. Our results strongly indicate that the\ntemperature enhancement of the conductivity reported in the recent study (Yan\nand Fuhrer, Phys. Rev. Lett. 107, 206601 (2011)) and attributed to the effect\nof dopant correlations was most likely caused by other factors not related to\nthe correlations in the scattering potential.",
        "positive": "Full counting statistics of information content and particle number: We consider a bipartite quantum conductor and discuss the joint probability\ndistribution of particle number in a subsystem and the self-information\nassociated with the reduced density matrix of the subsystem. By extending the\nmulti-contour Keldysh Green function technique, we calculate the R\\'enyi\nentropy of a positive integer order $M$ subjected to the particle number\nconstraint, from which we derive the joint probability distribution. For\nenergy-independent transmission, we derive the time dependence of the\naccessible entanglement entropy, or the conditional entropy. We analyze the\njoint probability distribution for energy-dependent transmission probability at\nthe steady state under the coherent resonant tunneling and the incoherent\nsequential tunneling conditions. We also discuss the probability distribution\nof the efficiency, which measures the information content transfered by a\nsingle electron."
    },
    {
        "anchor": "Anomalies in thickness measurements of graphene and few layer graphite\n  crystals by tapping mode atomic force microscopy: Atomic Force Microscopy (AFM) in the tapping (intermittent contact) mode is a\ncommonly used tool to measure the thickness of graphene and few layer graphene\n(FLG) flakes on silicon oxide surfaces. It is a convenient tool to quickly\ndetermine the thickness of individual FLG films. However, reports from\nliterature show a large variation of the measured thickness of graphene layers.\nThis paper is focused on the imaging mechanism of tapping mode AFM (TAFM) when\nmeasuring graphene and FLG thickness and we show that at certain measurement\nparameters significant deviations can be introduced in the measured thickness\nof FLG flakes. An increase of as much as 1 nm can be observed in the measured\nheight of FLG crystallites, when using an improperly chosen range of free\namplitude values of the tapping cantilever. We present comparative Raman\nspectroscopy and TAFM measurements on selected single and multilayer graphene\nfilms, based on which we suggest ways to correctly measure graphene and FLG\nthickness using TAFM.",
        "positive": "Electronic transport in a series of multiple arbitrary tunnel junctions: Monte Carlo simulations and an analytical approach within the framework of a\nsemiclassical model are presented which permit the determination of Coulomb\nblockade and single electron charging effects for multiple tunnel junctions\ncoupled in series. The Coulomb gap in the I(V) curves can be expressed as a\nsimple function of the capacitances in the series. Furthermore, the magnitude\nof the differential conductivity at current onset is calculated in terms of the\nmodel. The results are discussed with respect to the number of junctions."
    },
    {
        "anchor": "Graphene as a tunable THz reservoir for shaping the Mollow triplet of an\n  artificial atom via plasmonic effects: Using a realistic quantum master equation we show that the resonance\nfluorescence spectra of a two-level artificial atom (quantum dot) can be tuned\nby adjusting its photonic local density of states via biasing of one or more\ngraphene monolayers. The structured photon reservoir is included using a photon\nGreen function theory which fully accounts for the loss and dispersion. The\nfield-driven Mollow triplet spectrum can be actively controlled by the graphene\nbias in the THz frequency regime. We also consider the effect of a dielectric\nsupport environment, and multiple graphene layers, on the emitted fluorescence.\nFinally, thermal bath effects are considered and shown to be important for low\nTHz frequencies.",
        "positive": "Aspects of Anisotropic Fractional Quantum Hall Effect in Phosphorene: We have analyzed the effects of the anisotropic energy bands of phosphorene\non magnetoroton branches for electrons and holes in the two Landau levels close\nto the band edges. We have found that the fractional quantum Hall effect gap in\nthe lowest (highest) Landau level in conduction (valance) band is slightly\nlarger than that for conventional semiconductor systems and therefore\nexperimentally observable. We also found that the magnetoroton mode for both\nelectrons and holes consists of two branches with two minima due to the\nanisotropy. Additionally, we show that due to the anisotropy, there is a second\nmode with positive dispersion, well separated from the magnetoroton mode for\nsmall wave vectors. These novel features of the collective mode can be observed\nin resonant inelastic light scattering experiments."
    },
    {
        "anchor": "Origin of the Magnetic Spin Hall Effect: Spin Current Vorticity in the\n  Fermi Sea: The interplay of spin-orbit coupling (SOC) and magnetism gives rise to a\nplethora of charge-to-spin conversion phenomena that harbor great potential for\nspintronics applications. In addition to the spin Hall effect, magnets may\nexhibit a magnetic spin Hall effect (MSHE), as was recently discovered [Kimata\n\\textit{et al.}, Nature \\textbf{565}, 627-630 (2019)]. To date, the MSHE is\nstill awaiting its intuitive explanation. Here we relate the MSHE to the\nvorticity of spin currents in the Fermi sea, which explains pictorially the\norigin of the MSHE. For all magnetic Laue groups that allow for nonzero spin\ncurrent vorticities the related tensor elements of the MSH conductivity are\ngiven. Minimal requirements for the occurrence of a MSHE are compatibility with\neither a magnetization or a magnetic toroidal quadrupole. This finding implies\nin particular that the MSHE is expected in all ferromagnets with sufficiently\nlarge SOC. To substantiate our symmetry analysis, we present various models, in\nparticular a two-dimensional magnetized Rashba electron gas, that corroborate\nan interpretation by means of spin current vortices. Considering thermally\ninduced spin transport and the magnetic spin Nernst effect in magnetic\ninsulators, which are brought about by magnons, our findings for electron\ntransport can be carried over to the realm of spincaloritronics, heat-to-spin\nconversion, and energy harvesting.",
        "positive": "Wiedemann-Franz law in graphene in the presence of a weak magnetic field: The experimental work [J. Crossno et al., Science 351, 1058 (2016)], which\nreported the violation of the Wiedemann-Franz law in monolayer graphene\ncharacterized by a sharp peak of the Lorenz ratio at a finite temperature, has\nnot been fully explained. Our previous work [Y.-T. Tu and S. Das Sarma, Phys.\nRev. B 107, 085401 (2023)] provided a possible explanation through a\nBoltzmann-transport model with bipolar diffusion and an energy gap possibly\ninduced by the substrate. In this paper, we extend our calculation to include a\nweak magnetic field perpendicular to the graphene layer, which is\nexperimentally relevant, and may shed light on the possible violation or not of\nthe Wiedemann-Franz law. We find that the magnetic field enhances the size of\nthe peak of the Lorenz ratio but has little effect on its position, and that\nthe transverse component of the Lorenz ratio can be either positive or negative\ndepending on the parameter regime. In addition, we do the same calculation for\nbilayer graphene in the presence of a magnetic field and show the qualitative\nsimilarity with monolayer graphene. Our work should motivate\nmagnetic-field-dependent experiments elucidating the nature of the charge\ncarriers in graphene layers."
    },
    {
        "anchor": "Proximity-induced triplet superconductivity in Rashba materials: We study a proximity junction between a conventional s-wave superconductor\nand a conductor with Rashba spin-orbit coupling, with a specific focus on the\nspin structure of the induced pairing amplitude. We find that spin-triplet\npairing correlations are induced by spin-orbit coupling in both one- and\ntwo-dimensional systems due to the lifted spin degeneracy. Additionally, this\ninduced triplet pairing has a component with an odd frequency dependence that\nis robust to disorder. Our predictions are based on the solutions of the exact\nGor'kov equations and are beyond the quasiclassical approximation.",
        "positive": "Probing microwave capacitance of self-assembled quantum dots: Self-assembled quantum dots have remarkable optical, electronic and\nspintronic properties that make them leading candidates for quantum information\ntechnologies. Their characterization requires rapid and local determination of\nboth charge and spin degrees of freedom. We present a way to probe the\ncapacitance of small ensembles of quantum dots at microwave frequencies. The\ntechnique employs a capacitance sensor based on a microwave microstrip\nresonator with sensitivity ~10^(-19) F/rt(Hz), high enough to probe single\nelectrons. The integration of this design in a scanning microscope will provide\nan important tool for investigating single charge and spin dynamics in\nself-assembled quantum dot systems."
    },
    {
        "anchor": "Transport through side-coupled double quantum dots: from weak to strong\n  interdot coupling: We report low-temperature transport measurements through a double quantum dot\ndevice in a configuration where one of the quantum dots is coupled directly to\nthe source and drain electrodes, and a second (side-coupled) quantum dot\ninteracts electrostatically and via tunneling to the first one. As the interdot\ncoupling increases, a crossover from weak to strong interdot tunneling is\nobserved in the charge stability diagrams that present a complex pattern with\nmergings and apparent crossings of Coulomb blockade peaks. While the weak\ncoupling regime can be understood by considering a single level on each dot, in\nthe intermediate and strong coupling regimes, the multi-level nature of the\nquantum dots needs to be taken into account. Surprisingly, both in the strong\nand weak coupling regimes, the double quantum dot states are mainly localized\non each dot for most values of the parameters. Only in an intermediate coupling\nregime the device presents a single dot-like molecular behavior as the\nmolecular wavefunctions weight is evenly distributed between the quantum dots.\nAt temperatures larger than the interdot coupling energy scale, a loss of\ncoherence of the molecular states is observed.",
        "positive": "Fast pick up technique for high quality heterostructures of bilayer\n  graphene and hexagonal boron nitride: We present a fast method to fabricate high quality heterostructure devices by\npicking up crystals of arbitrary sizes. Bilayer graphene is encapsulated with\nhexagonal boron nitride to demonstrate this approach, showing good electronic\nquality with mobilities ranging from 17 000 cm^2/V/s at room temperature to 49\n000 cm^2/V/s at 4.2 K, and entering the quantum Hall regime below 0.5 T. This\nmethod provides a strong and useful tool for the fabrication of future high\nquality layered crystal devices."
    },
    {
        "anchor": "Magnetism-induced massive Dirac spectra and topological defects in the\n  surface state of Cr-doped Bi$_2$Se$_3$-bilayer topological insulators: Proximity-induced magnetic effects on the surface Dirac spectra of\ntopological insulators are investigated by scanning tunneling spectroscopic\n(STS) studies of bilayer structures consisting of undoped Bi2Se3 thin films on\ntop of Cr-doped Bi2Se3 layers. For thickness of the top Bi2Se3 layer equal to\nor smaller than 3 quintuple layers (QL), a spatially inhomogeneous surface\nspectral gap \\Delta opens up below T_c^{2D}, which is much higher than the bulk\nCurie temperature T_c^{3D}. The mean value and spatial homogeneity of the gap\n\\Delta generally increase with increasing c-axis magnetic field (H) and\nincreasing Cr doping level (x), suggesting that the physical origin of this\nsurface gap is associated with proximity-induced c-axis ferromagnetism. On the\nother hand, the temperature (T) dependence of \\Delta is non-monotonic, showing\nan initial increase below T_c^{2D} followed by a dip and then reaching maximum\nat T << T_c^{3D}. These phenomena may be attributed to proximity magnetism\ninduced by two types of contributions with different temperature dependence: a\n3D contribution from the bulk magnetism that dominates at low T, and a 2D\ncontribution associated with the RKKY interactions mediated by surface Dirac\nfermions, which dominates at T_c^{3D} << T < T_c^{2D}. Additionally, spatially\nlocalized sharp resonant spectra are found along the boundaries of gapped and\ngapless regions. These spectral resonances are long-lived at H = 0 and become\nsuppressed under strong c-axis magnetic fields, and are attributed to magnetic\nimpurity-induced topological defects in the spin texture of surface Dirac\nfermions.",
        "positive": "Conductance anomalies and the extended Anderson model for nearly perfect\n  quantum wires: Anomalies near the conductance threshold of nearly perfect semiconductor\nquantum wires are explained in terms of singlet and triplet resonances of\nconduction electrons with a single weakly-bound electron in the wire. This is\nshown to be a universal effect for a wide range of situations in which the\neffective single-electron confinement is weak. The robustness of this generic\nbehavior is investigated numerically for a wide range of shapes and sizes of\ncylindrical wires with a bulge. The dependence on gate voltage, source-drain\nvoltage and magnetic field is discussed within the framework of an extended\nHubbard model. This model is mapped onto an extended Anderson model, which in\nthe limit of low temperatures is expected to lead to Kondo resonance physics\nand pronounced many-body effects."
    },
    {
        "anchor": "Superconductivity from electronic interactions and spin-orbit\n  enhancement in bilayer and trilayer graphene: We discuss a Kohn-Luttinger-like mechanism for superconductivity in Bernal\nbilayer graphene and rhombohedral trilayer graphene. Working within the\ncontinuum model description, we find that the screened long-range Coulomb\ninteraction alone gives rise to superconductivity with critical temperatures\nthat agree with experiments. We observe that the order parameter changes sign\nbetween valleys, which implies that both materials are valley-singlet,\nspin-triplet superconductors. Adding Ising spin-orbit coupling leads to a\nsignificant enhancement in the critical temperature, also in line with\nexperiment, and the superconducting order parameter shows locking between the\nspin and valley degrees of freedom.",
        "positive": "Artificial ferroelectricity due to anomalous Hall effect in magnetic\n  tunnel junctions: We theoretically investigated Anomalous Hall Effect (AHE) and Spin Hall\nEffect (SHE) transversally to the insulating spacer O, in magnetic tunnel\njunctions of the form F/O/F where F are ferromagnetic layers and O represents a\ntunnel barrier. We considered the case of purely ballistic (quantum mechanical)\ntransport, taking into account the assymetric scattering due to spin-orbit\ninteraction in the tunnel barrier. AHE and SHE in the considered case have a\nsurface nature due to proximity effect. Their amplitude is in first order of\nthe scattering potential. This contrasts with ferromagnetic metals wherein\nthese effect are in second (side-jump scattering) and third (skew scattering)\norder on these potentials. The value of AHE voltage in insulating spacer may be\nmuch larger than in metallic ferromagnetic electrodes. For the antiparallel\norientation of the magnetizations in the two F-electrodes, a spontaneous Hall\nvoltage exists even at zero applied voltage. Therefore an insulating spacer\nsandwiched between two ferromagnetic layers can be considered as exhibiting a\nspontaneous ferroelectricity."
    },
    {
        "anchor": "Floquet topological phases on a honeycomb lattice using elliptically\n  polarized light: We study the effect of driving a two-dimensional honeycomb system out of\nequilibrium using an elliptically polarized light as a time-dependent\nperturbation. In particular, we try to understand the topological phase diagram\nof this driven system when the external drive is a vector potential given by\n${\\bf A}(t) = (A_{0x} \\cos(\\Omega t), A_{0y} \\cos(\\Omega t + \\phi_0))$. These\ntopological phases are characterized by the Floquet Chern number which, in each\nof these phases, is related to the number of robust edge modes on a nanoribbon.\nWe show that varying the ratio $A_{0x}/A_{0y}$ of the external drive is a\npossible way to take the system from a trivial to a topological phase and vice\nversa.",
        "positive": "Achieving Large, Tunable Strain in Monolayer Transition-Metal\n  Dichalcogenides: We describe a facile technique based on polymer encapsulation to apply\nseveral percent controllable strains to monolayer and few-layer Transition\nMetal Dichalcogenides (TMDs). We use this technique to study the lattice\nresponse to strain via polarized Raman spectroscopy in monolayer WSe2 and WS2.\nThe application of strain causes mode-dependent redshifts, with larger shift\nrates observed for in-plane modes. We observe a splitting of the degeneracy of\nthe in-plane E' modes in both materials and measure the Gruneisen parameters.\nAt large strain, we observe that the reduction of crystal symmetry can lead to\na change in the polarization response of the A' mode in WS2. While both WSe2\nand WS2 exhibit similar qualitative changes in the phonon structure with\nstrain, we observe much larger changes in mode positions and intensities with\nstrain in WS2. These differences can be explained simply by the degree of\niconicity of the metal-chalcogen bond."
    },
    {
        "anchor": "Leakage-induced decoherence during single electron spin manipulation in\n  a double quantum dot: Coherent single electron spin oscillation in a double quantum dot system\ndriven by a magnetic electron spin resonance field is studied theoretically\nusing a Bloch-type rate equation approach. The oscillation frequency and\nrelaxation time obtained using typical model parameters are consistent with\nexperiment findings. The dominant decoherence mechanism is identified to be a\nleakage current through a Coulomb blockade barrier at a quantum dot during the\nspin manipulation. Nuclear field fluctuations which induce a long relaxation\ntime are found to contribute only negligibly to the decoherence despite an\nearlier suggestion.",
        "positive": "Phase-sensitive transport at a normal metal-superconductor interface\n  close to a Josephson junction: Phase- and voltage bias-sensitive quasiparticle transport at a double\n$NIS_1IS_2$ interface is considered. The barriers $I$ range from tunnel to\ntransparent, and the intermediate region $S_1$ has a width comparable to the\nsuperconducting coherence length. A phase difference $\\varphi$ is applied to\nthe Josephson junction $S_1IS_2$. The normal and Andreev reflections at the\n$NIS_1$ interface become $\\varphi$-sensitive, and transport is governed by\ninterferences within the narrow $S_1$ region, both in the normal and anomalous\nchannels. The subgap conductance is separately (energy $E$)- and (phase\n$\\varphi$)- symmetric. Above the superconducting gap, the conductance is in\ngeneral not symmetric even if $(E,\\varphi)$ is changed in $(-E,-\\varphi)$, but\nthe symmetry is restored by averaging Fermi oscillations. The Tomasch\noscillations are amplified by the phase difference. The subgap conductance\nexhibits a resonant structure at the energy of the Andreev bound states (ABS)\nof the $S_1IS_2$ junction, providing a side-spectroscopy of such states.\nDepending on the relative transparencies of the junctions, the resonance can\nincrease or reduce the conductance, and it can even vanish for $\\varphi=\\pi$,\nfeaturing total reflection of quasiparticles at $NS_1$ by the ABS at $S_1S_2$."
    },
    {
        "anchor": "Electronic structure in a transition metal dipnictide TaAs2: The family of transition metal dipnictides (TMDs) has been of theoretical and\nexperimental interest because this family hosts topological states and\nextremely large magnetoresistance (MR). Recently, TaAs2, a member of this\nfamily, has been predicted to support a topological crystalline insulating\nstate. Here, by using high resolution. Angle resolved photoemission\nspectroscopy (ARPES), we reveal both closed and open pockets in the metallic\nFermi surface and linearly dispersive bands on the (201) surface, along with\nthe presence of extreme MR observed from magneto-transport measurements. A\ncomparison of the ARPES results with first-principles computations show that\nthe linearly dispersive bands on the measured surface of TaAs2 are trivial bulk\nbands. The absence of symmetry-protected surface state on the (201) surface\nindicates its topologically dark nature. The presence of open Fermi surface\nfeatures suggests that the open orbit fermiology could contribute to the\nextremely large MR of TaAs.",
        "positive": "Electron-hole spin flip-flop in semiconductor quantum dots: We use temporally resolved intensity cross-correlation measurements to\nidentify the biexciton-exciton radiative cascades in a negatively charged QD.\nThe polarization sensitive correlation measurements show unambiguously that the\nexcited two electron triplet states relax non-radiatively to their singlet\nground state via a spin non conserving flip-flop with the ground state heavy\nhole. We explain this mechanism in terms of resonant coupling between the\nconfined electron states and an LO phonon. This resonant interaction together\nwith the electron-hole exchange interaction provides an efficient mechanism for\nthis, otherwise spin-blockaded, electronic relaxation."
    },
    {
        "anchor": "Collective modes and quantum effects in two-dimensional nanofluidic\n  channels: Nanoscale fluid transport is typically pictured in terms of atomic-scale\ndynamics, as is natural in the real-space framework of molecular simulations.\nAn alternative Fourier-space picture, that involves the collective charge\nfluctuation modes of both the liquid and the confining wall, has recently been\nsuccessful at predicting new nanofluidic phenomena such as quantum friction and\nnear-field heat transfer, that rely on the coupling of those fluctuations.\nHere, we study the charge fluctuation modes of a two-dimensional (planar)\nnanofluidic channel. Introducing confined response functions that generalize\nthe notion of surface response function, we show that the channel walls exhibit\ncoupled plasmon modes as soon as the confinement is comparable to the plasmon\nwavelength. Conversely, the water fluctuations remain remarkably bulk-like,\nwith significant confinement effects arising only when the wall spacing is\nreduced to 7 A. We apply the confined response formalism to predict the\ndependence of the solid-water quantum friction and thermal boundary conductance\non channel width for model channel wall materials. Our results provide a\ngeneral framework for Coulomb interactions of fluctuating matter in nanoscale\nconfinement.",
        "positive": "Intense terahertz laser fields on a quantum dot with Rashba spin-orbit\n  coupling: We investigate the effects of the intense terahertz laser field and the\nspin-orbit coupling on single electron spin in a quantum dot. The laser field\nand the spin-orbit coupling can strongly affect the electron density of states\nand can excite a magnetic moment.\n  The direction of the magnetic moment depends on the symmetries of the system,\nand its amplitude can be tuned by the strength and frequency of the laser field\nas well as the spin-orbit coupling."
    },
    {
        "anchor": "Effect of uniaxial stress on the interference of polaritonic waves in\n  wide quantum wells: A theory of polaritonic states is developed for a nanostructure with a wide\nquantum well stressed perpendicular to the growth axis of the heterostructure.\nThe role of the $K$-linear terms appearing in the exciton Hamiltonian under the\nstress is discussed. Exciton reflectance spectra are theoretically modeled for\nthe nanostructure. It is predicted that the spectral oscillations caused by\ninterference of the exciton-like and photon-like polariton modes disappear with\nthe increase of applied pressure and then appear again with opposite phase\nrelative to that observed at low pressure. Effects of gyrotropy and convergence\nof masses of excitons with heavy and light holes due to their mixing by the\ndeformation is also considered. Numerical estimates performed for the GaAs\nwells show that these effects can be experimentally observed at pressure $P <\n1$~GPa for the well widths of a fraction of micron.",
        "positive": "Issues pertaining to D'yakonov-Perel' spin relaxation in quantum wire\n  channels: We elucidate the origin and nature of the D'yakonov-Perel' spin relaxation in\na quantum wire structure, showing (analytically) that there are three necessary\nconditions for it to exist: (i) transport must be multi-channeled, (ii) there\nmust be a Rashba spin orbit interaction in the wire, and (iii) there must also\nbe a Dresselhaus spin orbit interaction. Therefore, the only effective way to\ncompletely eliminate the D'yakonov-Perel' relaxation in compound semiconductor\nchannels with structural and bulk inversion asymmetry is to ensure strictly\nsingle channeled transport. In view of that, recent proposals in the literature\nthat advocate using multi-channeled quantum wires for spin transistors appear\nill-advised."
    },
    {
        "anchor": "Evidence for a new symmetry breaking mechanism reorienting quantum Hall\n  nematics: We report on the effect of in-plane magnetic field $B_\\parallel$ on stripe\nphases in higher ($N=2,3$) Landau levels of a high-mobility 2D electron gas. In\naccord with previous studies, we find that a modest $B_\\parallel$ applied\nparallel to the native stripes aligns them perpendicular to it. However, upon\nfurther increase of $B_\\parallel$, stripes are reoriented back to their native\ndirection. Remarkably, applying $B_\\parallel$ perpendicular to the native\nstripes also aligns stripes parallel to it. Thus, regardless of the initial\norientation of stripes with respect to $B_\\parallel$, stripes are ultimately\naligned \\emph{parallel} to $B_\\parallel$. These findings provide evidence for a\n$B_\\parallel$-induced symmetry breaking mechanism which challenge current\nunderstanding of the role of $B_\\parallel$ and should be taken into account\nwhen determining the strength of the native symmetry breaking potential.\nFinally, our results might indicate nontrivial coupling between the native and\nexternal symmetry breaking fields, which has not yet been theoretically\nconsidered.",
        "positive": "Emergence of Majorana modes in cylindrical nanowires: We present calculations of Majorana edge modes in cylindrical nanowires of a\nsemiconductor material with proximity-induced superconductivity. We consider a\nRashba field along the transverse direction and an applied magnetic field in\narbitrary orientation. Our analysis is based on exact numerical\ndiagonalizations for the finite cylinder and on the complex band structure for\nthe semi-infinite one. Orbital effects are responsible for a strong anisotropy\nof the critical field for which the effective gap vanishes. Robust Majorana\nmodes are induced by the parallel field component and we find regimes with more\nthan one Majorana mode on the same edge. Experimentally, they would manifest as\na specific sequence of zero-bias conductances as a function of magnetic field.\nIn the finite cylinder, a degradation of the Majorana modes due to interference\nof the two edges leads to oscillating non zero energies for large enough\nfields."
    },
    {
        "anchor": "Optical signatures of periodic magnetization: the moir\u00e9 Zeeman effect: Detecting magnetic order at the nanoscale is of central interest for the\nstudy of quantum magnetism in general, and the emerging field of moir\\'e\nmagnets in particular. Here, we analyze the exciton band structure that arises\nfrom a periodic modulation of the valley Zeeman effect. Despite long-range\nelectron-hole exchange interactions, we find a sizable splitting in the energy\nof the bright circularly-polarized exciton Umklapp resonances, which serves as\na direct optical probe of magnetic order. We first analyze quantum moir\\'e\nmagnets realized by periodic ordering of electron spins in Mott-Wigner states\nof transition metal dichalcogenide (TMD) monolayers or twisted bilayers: we\nshow that spin-valley dependent exciton-electron interactions allow for probing\nthe spin-valley order of electrons and demonstrate that it is possible to\nobserve unique signatures of ferromagnetic order in a triangular lattice and\nboth ferromagnetic and N\\'eel order in a honeycomb lattice. We then focus on\nsemiclassical moir\\'e magnets realized in twisted bilayers of ferromagnetic\nmaterials: we propose a detection scheme for moir\\'e magnetism which is based\non inter-layer exchange coupling between spins in a moir\\'e magnet and excitons\nin a TMD monolayer.",
        "positive": "SQUID Metamaterials: Tuneability and Multistability: An overview of several dynamic properties of SQUID metamaterials is given in\nthe presence of both constant and alternating magnetic field. The total current\nas a function of the driving frequency exhibits hysteretic effects which are\nfavored by low levels of disorder. Multistability in the current states leads\nto multiple magnetic responses with different value of magnetic permeability.\nSQUID metamaterials exhibit wide-band tuneability which is periodic with the\napplied constant magnetic field; the numerical calculations reproduce fairly\nwell recent experimental results. Current work also reveals the possibility for\nwave transmission through nonlinear bands, which is briefly discussed."
    },
    {
        "anchor": "Disorder-Induced Phase Transitions in Three-Dimensional Chiral\n  Second-Order Topological Insulator: Topological insulators have been extended to higher-order versions that\npossess topological hinge or corner states in lower dimensions. However, their\nrobustness against disorder is still unclear. Here, we theoretically\ninvestigate the phase transitions of three-dimensional (3D) chiral second-order\ntopological insulator (SOTI) in the presence of disorders. Our results show\nthat, by increasing disorder strength, the nonzero densities of states of side\nsurface and bulk emerge at critical disorder strengths of $W_{S}$ and $W_{B}$,\nrespectively. The spectral function indicates that the bulk gap is only closed\nat one of the $R_{4z}\\mathcal{T}$-invariant points, i.e., $\\Gamma_{3}$. The\nclosing of side surface gap or bulk gap is ascribed to the significant decrease\nof the elastic mean free time of quasi-particles. Because of the localization\nof side surface states, we find that the 3D chiral SOTI is robust at an\naveraged quantized conductance of $2e^{2}/h$ with disorder strength up to\n$W_{B}$. When the disorder strength is beyond $W_{B}$, the 3D chiral SOTI is\nthen successively driven into two phases, i.e., diffusive metallic phase and\nAnderson insulating phase. Furthermore, an averaged conductance plateau of\n$e^{2}/h$ emerges in the diffusive metallic phase.",
        "positive": "Periodically modulated quantum nonlinear oscillators: This book chapter describes the dynamics of a modulated oscillator for\nresonant and nonresonant modulation. Two types of resonant modulation are\nconsidered: additive, with frequency close to the oscillator eigenfrequency,\nand parametric, with frequency close to twice the eigenfrequency. It is shown\nthat relaxation of the oscillator is accompanied by quantum noise, which leads\nto a finite-width distribution over quantum states even for T=0. The quantum\nnoise also leads to switching between coexisting vibrational states via\ntransitions over the barrier in phase space. The switching mechanism, quantum\nactivation, has no analog in thermal equilibrium systems. The switching rates\ndisplay characteristic scaling near bifurcation points. The power and\nabsorption/amplification spectra of modulated oscillators are studied,\nincluding their fine structure. Nonresonant modulation can lead to cooling,\nheating, or self-sustained vibrations of an oscillator. The relation between\nthe previously discussed direct nonresonant excitation of the oscillator and\nthe excitation mechanism studied in optomechanics is analyzed."
    },
    {
        "anchor": "Reply to arXiv:1212.3831v1 \"Comment on: Magnetotransport through\n  graphene spin valves and its following works\" by Y. Zhou and M.W. Wu: In their comment arXiv:1212.3831v1 Y. Zhou and M.W. Wu claim that the\nfundamental transport equation relating the current to the transmission\nfunction, used by us and in fact by numerous other researchers, is invalid for\nextended systems and should be corrected. They provide a \"correct\" new formula\nfor transport in extended systems. This would be indeed a surprising new aspect\nof quantum transport theory. Here we show mathematically, however, that the new\nformula is a misconception resulting from adding an energy and momentum\ndependent function that has to vanish due to fundamental reasons. Results and\nconclusions stemming from adding this function are irrelevant. The known\nestablished formulas for quantum transport are consistent with each others\nunder the well-documented conditions.",
        "positive": "Disordered electron liquid in double quantum well heterostructures:\n  Renormalization group analysis and dephasing rate: We report a detailed study of the influence of the electron-electron\ninteraction on physical observables (conductance, etc.) of a disordered\nelectron liquid in double quantum well heterostructure. We find that even in\nthe case of common elastic scattering off electrons in both quantum wells, the\nasymmetry in the electron-electron interaction across and within quantum wells\ndecouples them at low temperatures. Our results are in quantitative agreement\nwith recent transport experiments on the gated double quantum well\nAl$_x$Ga$_{1-x}$As/GaAs/Al$_x$Ga$_{1-x}$As heterostructures."
    },
    {
        "anchor": "ATR excitation of surface polaritons at the interface between a metal\n  and a layer of nanocrystal quantum dots: Surface plasmon-polaritons in a multilayer structure consisting of a metallic\nfilm and one or more layers of nanocrystal (NC) quantum dots (QDs) are studied.\nIt is shown that there is resonance coupling between the plasmon-polaritons\npropagating along the metal/NC-layer interface and excitons confined in the\ndots, which makes a considerable effect on the optical properties of the\nstructure unless the dispersion of the QD size is too large. This coupling can\nbe explored in order to selectively excite QDs of different size by using an\nattenuated total reflection (ATR) structure. It opens the possibility of\ncontrol of the relative intensity of light of different color, emitted by the\nQDs of different size.",
        "positive": "Weak localization in ferromagnetic (Ga,Mn)As nanostructures: We report on the observation of weak localization in arrays of (Ga,Mn)As\nnanowires at millikelvin temperatures. The corresponding phase coherence length\nis typically between 100 nm and 200 nm at 20 mK. Strong spin-orbit interaction\nin the material is manifested by a weak anti-localization correction around\nzero magnetic field."
    },
    {
        "anchor": "A Two-Dimensional Carbon Semiconductor: We show that patterned defects can be used to disrupt the sub-lattice\nsymmetry of graphene so as to open up a band gap. This way of modifying\ngraphene's electronic structure does not rely on external agencies, the\naddition of new elements or special boundaries. The method is used to predict a\nplanar, low energy, graphene allotrope with a band gap of 1.2 eV. This defect\nengineering also allows semiconducting ribbons of carbon to be fabricated\nwithin graphene. Linear arrangements of defects lead to naturally embedded\nribbons of the semiconducting material in graphene, offering the prospect of\ntwo-dimensional circuit logic composed entirely of carbon.",
        "positive": "Symmetry-controlled singlet-triplet transition in a double-barrier\n  quantum ring: We engineer a system of two strongly confined quantum dots to gain\nreproducible electrostatic control of the spin at zero magnetic field. Coupling\nthe dots in a tight ring-shaped potential with two tunnel barriers, we\ndemonstrate that an electric field can switch the electron ground state between\na singlet and a triplet configuration. Comparing our experimental co-tunneling\nspectroscopy data to a full many-body treatment of interacting electrons in a\ndouble-barrier quantum ring, we find excellent agreement in the evolution of\nmany-body states with electric and magnetic fields. The calculations show that\nthe singlet-triplet energy crossover, not found in conventionally coupled\nquantum dots, is made possible by the ring-shaped geometry of the confining\npotential."
    },
    {
        "anchor": "Photo-current and photo-voltage oscillations in the two-dimensional\n  electron system: screening and \"anti-screening\" of a potential profile: We observe in state-of-the-art GaAs based 2D electron systems microwave\ninduced photo-current and photo-voltage oscillations around zero as a function\nof the applied magnetic field. The photo-signals pass zero whenever the\nmicrowave frequency is close to a multiple of the cyclotron resonance\nfrequency. They originate from built-in electric fields due to for instance\nband bending at contacts. The oscillations correspond to a suppression\n(screening) or an enhancement (\"anti-screening\") of these fields by the\nphoto-excited electrons.",
        "positive": "Electronic Structure and Transport in Graphene/Haeckelite Hybrids: An\n  {\\em Ab Initio} Study: We combine {\\em ab initio} density functional theory (DFT) structural studies\nwith DFT-based nonequilibrium Green function calculations to investigate how\nthe presence of non-hexagonal rings affects electronic transport in graphitic\nstructures. We find that infinite monolayers, finite-width nanoribbons and\nnanotubes formed of 5-8 haeckelite with only 5- and 8-membered rings are\ngenerally more conductive than their graphene-based counterparts. Presence of\nhaeckelite defect lines in the perfect graphitic structure, a model of grain\nboundaries in CVD-grown graphene, increases the electronic conductivity and\nrenders it highly anisotropic."
    },
    {
        "anchor": "Magnetic field filtering of the hinge supercurrent in unconventional\n  metal NiTe$_2$-based Josephson junctions: Topological materials with boundary (surface/edge/hinge) states have\nattracted tremendous research interest. Besides, unconventional (obstructed\natomic) materials have recently drawn lots of attention owing to their\nobstructed boundary states. Experimentally, Josephson junctions (JJs)\nconstructed on materials with boundary states produce the peculiar boundary\nsupercurrent, which was utilized as a powerful diagnostic approach. Here, we\nreport the observations of conspicuous hinge supercurrent in NiTe$_2$-based\nJJs. Particularly, applying an in-plane magnetic field along the Josephson\ncurrent could rapidly suppress the bulk supercurrent and retain the nearly pure\nhinge supercurrent, namely the magnetic field filtering of supercurrent.\nFurther systematic comparative analysis and theoretical calculations\ndemonstrate the existence of unconventional nature and obstructed hinge states\nin NiTe$_2$. Our results revealed the unique hinge states in unconventional\nmetal NiTe$_2$, and demonstrated in-plane magnetic field as an efficient method\nto filter out the futile bulk contributions and thereby to highlight the hinge\nstates hidden in topological/unconventional materials.",
        "positive": "Magnonic thermal transport using the quantum Boltzmann equation: We present a formula for thermal transport in the bulk of Bose systems based\non the quantum Boltzmann equation (QBE). First, starting from the quantum\nkinetic equation and using the Born approximation for impurity scattering, we\nderive the QBE of Bose systems and provide a formula for thermal transport\nsubjected to a temperature gradient. Next, we apply the formula to magnons.\nAssuming a relaxation time approximation and focusing on the linear response\nregime, we show that the longitudinal thermal conductivity of the QBE exhibits\nthe different behavior from the conventional. The thermal conductivity of the\nQBE reduces to the Drude-type in the limit of the quasiparticle approximation,\nwhile not in the absence of the approximation. Finally, applying the\nquasiparticle approximation to the QBE, we find that the correction to the\nconventional Boltzmann equation is integrated as the self-energy into the\nspectral function of the QBE, and this enhances the thermal conductivity. Thus\nwe shed light on the thermal transport property of the QBE beyond the\nconventional."
    },
    {
        "anchor": "Hopfions emerge in ferroelectrics: Paradigmatic knotted solitons, Hopfions, that are characterized by\ntopological Hopf invariant, are widely investigated in the diverse areas\nranging from high energy physics, cosmology and astrophysics to biology,\nmagneto- and hydrodynamics and condensed matter physics. Yet, while holding\nhigh promise for applications, they remain elusive and under-explored. Here we\ndemonstrate that Hopfions emerge as a basic configuration of polarization field\nin confined ferroelectric nanoparticles. Our findings establish that Hopfions\ngovern a wealth of novel functionalities in the electromagnetic response of\ncomposite nanomaterials opening route to unprecedented technological\napplications.",
        "positive": "Anomalous Floquet tunneling in uniaxially strained graphene: The interplay of strain engineering and photon-assisted tunneling of\nelectrons in graphene is considered for giving rise to atypical transport\nphenomena. The combination of uniaxial strain and a time-periodic potential\nbarrier helps to control the particle transmission for a wide range of tunable\nparameters. With the use of the tight-biding approach, the elasticity theory,\nand the Floquet scattering, we found an angular shift of the maximum\ntransmission in the sidebands for uniaxial strains breaking the mirror symmetry\nwith respect to the normal incidence, which is called anomalous Floquet\ntunneling. We show that electron tunneling depends strongly on the barrier\nwidth, incident angle, uniaxial strain, and the tuning of the time-periodic\npotential parameters. An adequate modulation of the barrier width and\noscillation amplitude serves to select the transmission in the sidebands. These\nfindings can be useful for controlling the electron current through the\nphoton-assisted tunneling being used in multiple nanotechnological\napplications."
    },
    {
        "anchor": "Comment on \"Non-equilibrium Electron Distribution in Presence of Kondo\n  Impurities\" (cond-mat/0102150v2): An inadequate approximation and its consequences as well as an incorrect\nstatement made in cond-mat/0102150v2 are pointed out.",
        "positive": "Modeling of dual-metal Schottky contacts based silicon micro and nano\n  wire solar cells: We study solar cell properties of single silicon wires connected at their\nends to two dissimilar metals of different work functions. Effects of wire\ndimensions, the work functions of the metals, and minority carrier lifetimes on\nshort circuit current as well as open circuit voltage are studied. The most\nefficient photovoltaic behavior is found to occur when one metal makes a\nSchottky contact with the wire, and the other makes an Ohmic contact. As wire\nlength increases, both short circuit current and open circuit voltage increase\nbefore saturation occurs. Depending on the work function difference between the\nmetals and the wire dimensions, the saturation length increases by\napproximately an order of magnitude with a two order magnitude increase in\nminority carrier length. However current per surface area exposed to light is\nfound to decrease rapidly with increase in length. The use of a multi-contact\ninterdigitated design for long wires is investigated to increase the\nphotovoltaic response of the devices."
    },
    {
        "anchor": "Interfering Josephson diode effect and magnetochiral anisotropy in\n  Ta2Pd3Te5 asymmetric edge interferometer: Edge states of topological systems have attracted great interest due to their\nrobustness and linear dispersions. Here a superconducting-proximitized edge\ninterferometer is engineered on a second-order topological insulator Ta2Pd3Te5\nwith asymmetric edges to realize the interfering Josephson diode effect (JDE),\nwhich hosts many advantages, such as the high efficiency as much as 73% at tiny\napplied field 8.4 mT an ultra-low switching power around picowatt, and a giant\ninterfering magnetochiral anisotropy with a coefficient $\\gamma$ = 1.2 $\\times\n10^9$ T$^{-1}$A$^{-1}$ - three orders of magnitude larger than the reported\nrecord. As an important element to induce such JDE, the second-order harmonic\nin the current-phase relation is also experimentally confirmed by half Shapiro\nsteps. This edge interferometer offers a novel and effective method to enhance\nthe overall performance of JDE and magnetochiral anisotropy, and boosts great\npotential application for future superconducting quantum devices.",
        "positive": "Control over band structure and tunneling in Bilayer Graphene induced by\n  velocity engineering: The band structure and transport properties of massive Dirac Fermions in\nbilayer graphene with velocity modulation in space are investigated in presence\nof the previously created band gap. It is pointed out that the velocity\nengineering is considered as a factor to control the band gap of\nsymmetry-broken bilayer graphene. The band gap is direct and independent of\nvelocity value if velocity modulated in two layers is set up equally.\nOtherwise, in the case of interlayer asymmetric velocity, not only the band gap\nis indirect, but also the electron-hole symmetry fails. This band gap is\ncontrollable by the ratio of the velocity modulated in the upper layer to the\nvelocity modulated in the lower layer. In more detail, the shift of momentum\nfrom the conduction band edge to the valence band edge can be engineered by the\ngate bias and velocity ratio. A transfer matrix method is also elaborated to\ncalculate four-band coherent conductance through a velocity barrier possibly\nsubjected to a gate bias. Electronic transport depends on the ratio of velocity\nmodulated inside the barrier to the one for surrounding regions. As a result, a\nquantum version of total internal reflection is observed for enough thick\nvelocity barriers. Moreover, a transport gap originating from the applied gate\nbias is engineered by modulating velocity of the carriers in the upper and\nlower layers."
    },
    {
        "anchor": "Observation of Quantum Interference in Molecular Charge Transport: As the dimensions of a conductor approach the nano-scale, quantum effects\nwill begin to dominate its behavior. This entails the exciting possibility of\ncontrolling the conductance of a device by direct manipulation of the electron\nwave function. Such control has been most clearly demonstrated in mesoscopic\nsemiconductor structures at low temperatures. Indeed, the Aharanov-Bohm effect,\nconductance quantization and universal conductance fluctuations are direct\nmanifestations of the electron wave nature. However, an extension of this\nconcept to more practical emperatures has not been achieved so far. As\nmolecules are nano-scale objects with typical energy level spacings (~eV) much\nlarger than the thermal energy at 300 K (~25 meV), they are natural candidates\nto enable such a break-through. Fascinating phenomena including giant\nmagnetoresistance, Kondo effects and conductance switching, have previously\nbeen demonstrated at the molecular level. Here, we report direct evidence for\ndestructive quantum interference in charge transport through two-terminal\nmolecular junctions at room temperature. Furthermore, we show that the degree\nof interference can be controlled by simple chemical modifications of the\nmolecule. Not only does this provide the experimental demonstration of a new\nphenomenon in quantum charge transport, it also opens the road for a new type\nof molecular devices based on chemical or electrostatic control of quantum\ninterference.",
        "positive": "Quantum many-body simulation using monolayer exciton-polaritons in\n  coupled-cavities: Quantum simulation is a promising approach to understand complex strongly\ncorrelated many-body systems using relatively simple and tractable systems.\nPhoton-based quantum simulators have great advantages due to the possibility of\ndirect measurements of multi-particle correlations and ease of simulating\nnon-equilibrium physics. However, interparticle interaction in existing\nphotonic systems is often too weak limiting the potential of quantum\nsimulation. Here we propose an approach to enhance the interparticle\ninteraction using exciton-polaritons in MoS$_2$ monolayer quantum-dots embedded\nin 2D photonic crystal microcavities. Realistic calculation yields optimal\nrepulsive interaction in the range of $1$-$10$~meV --- more than an order of\nmagnitude greater than the state-of-art value. Such strong repulsive\ninteraction is found to emerge neither in the photon-blockade regime for small\nquantum dot nor in the polariton-blockade regime for large quantum dot, but in\nthe crossover between the two regimes with a moderate quantum-dot radius around\n20~nm. The optimal repulsive interaction is found to be largest in MoS$_2$\namong commonly used optoelectronic materials. Quantum simulation of strongly\ncorrelated many-body systems in a finite chain of coupled cavities and its\nexperimental signature are studied via exact diagonalization of the many-body\nHamiltonian. A method to simulate 1D superlattices for interacting\nexciton-polariton gases in serially coupled cavities is also proposed.\nRealistic considerations on experimental realizations reveal advantages of\ntransition metal dichalcogenide monolayer quantum-dots over conventional\nsemiconductor quantum-emitters."
    },
    {
        "anchor": "Ultrasonic force microscopy on 'poly(vinyl alcohol)/SrTiO3'\n  nano-perovskites hybrid films: Atomic Force Microscopy (AFM) and Ultrasonic Force Microscopy (UFM) have been\napplied to the characterization of composite samples formed by SrTiO 3 (STO)\nnanoparticles (NPs) and polyvinyl alcohol (PVA). The morphological features of\nthe STO NPs were much better resolved in UFM than in contact-mode AFM\ntopography. For high STO concentrations the individual STO NPs formed\nnanoclusters, which gathered in microaggregates. The STO aggregates, covered by\nPVA, exhibited no AFM frictional contrast, but were clearly distinguished from\nthe PVA matrix using UFM. Similar aggregation was observed for NPs in the\ncomposite samples than for NPs deposited on top of a flat silicon substrate\nfrom a milliQ water solution in the absence of polymer. In the hybrid films,\nmost STO nanoparticles typically presented a lower UFM contrast than the PVA\nmatrix, even though stiffer sample regions such as STO should give rise to a\nhigher UFM contrast. STO NPs with intermediate contrast were characterized by\nan UFM halo of lower contrast at the PVA/STO interface. The results may be\nexplained by considering that ultrasound is effectively damped on the nanometer\nscale at PVA/ STO interfaces. According to our data, the nanoscale ultrasonic\nresponse at the PVA/STO interface plays a fundamental role in the UFM image\ncontrast.",
        "positive": "Quantum dot in the pseudogap Kondo state: We investigate the transport properties of a (small) quantum dot connected to\nFermi liquid leads with a power-law density of states (DOS). Such a system, if\nexperimentally realizable, will have interesting physical properties including:\n(i) non-saturating Coulomb blockade peak widths; (ii) a non-unitary Kondo peak\nsymmetrically placed between the Coulomb blockade peaks; (iii) an absence of\nconductance away from particle-hole symmetry at sufficiently low temperatures;\nand (iv) evidence of a quantum critical point as a function of dot-lead\nhopping. These properties are compared and contrasted with one dimensional\nLuttinger systems exhibiting a power-law \"tunneling-DOS\"."
    },
    {
        "anchor": "Quantum Mott transition in a silicon quantum dot: Considering a double-barrier structure formed by a silicon quantum dot\ncovered by natural oxide, we derive simple conditions for the conductance of\nthe dot to become a step-like function of the number of doping atoms inside the\ndot, with negligible dependence on the actual position of the dopants. The\nfound conditions are feasible in experimentally available structures.",
        "positive": "Fast Computation of Scattering by Isolated Defects in Periodic\n  Dielectric Media: Scattering by an isolated defect embedded in a dielectric medium of two\ndimensional periodicity is of interest in many sub-fields of electrodynamics.\nPresent approaches to compute this scattering rely either on the Born\napproximation and its quasi-analytic extensions, or on \\emph{ab-initio}\ncomputation that requires large domain sizes to reduce the effects of boundary\nconditions. The Born approximation and its extensions are limited in scope,\nwhile the ab-initio approach suffers from its high numerical cost. In this\npaper, I introduce a hybrid scheme in which an effective local electric\nsusceptibility tensor of a defect is estimated by solving an inverse problem\nefficiently. The estimated tensor is embedded into an S-matrix formula based on\nthe reciprocity theorem. With this embedding, the computation of the S-matrix\nof the defect requires field solutions only in the unit cell of the background.\nIn practice, this scheme reduces the computational cost by almost two orders of\nmagnitude, while sacrificing little in accuracy. The scheme demonstrates that\nstatistical estimation can capture sufficient information from cheap\ncalculations to compute quantities in the far field. I outline the fundamental\ntheory and algorithms to carry out the computations in high dielectric contrast\nmaterials, including metals. I demonstrate the capabilities of this approach\nwith examples from optical inspection of nano-electronic circuitry where the\nBorn approximation fails and the existing methods for its extension are also\ninapplicable."
    },
    {
        "anchor": "Current-induced energy barrier suppression for electromigration from\n  first principles: We present an efficient method for evaluating current-induced forces in\nnanoscale junctions, which naturally integrates into the non-equilibrium\nGreen's function formalism implemented within density functional theory. This\nallows us to perform dynamical atomic relaxation in the presence of an electric\ncurrent while also evaluating the current-voltage characteristics. The central\nidea consists in expressing the system energy density matrix in terms of\nGreen's functions. In order to validate our implementation we perform a series\nof benchmark calculations, both at zero and finite bias. Firstly we evaluate\nthe current-induced forces acting over an Al nanowire and compare them with\npreviously published results for fixed geometries. Then we perform structural\nrelaxation of the same wires under bias and determine the critical voltage at\nwhich they break. We find that, while a perfectly straight wire does not break\nat any of the voltages considered, a zigzag wire is more fragile and snaps at\n1.4 V, with the Al atoms moving against the electron flow. Finally we\ndemonstrate the capability of our scheme to tackle the electromigration problem\nby studying the current-induced motion of a single Si atom covalently attached\nto the sidewall of a (4,4) armchair single-walled carbon nanotube. Our\ncalculations indicate that if Si is attached along the current path, then\ncurrent-induced forces can induce migration. In contrast, if the bonding site\nis away from the current path, then the adatom will remain stable regardless of\nthe voltage. An analysis based on decomposing the total force into a wind and\nan electrostatic component, as well as on a detailed evaluation of the bond\ncurrents, shows that this remarkable electromigration phenomenon is due solely\nto the position-dependent wind force.",
        "positive": "Influence of Dimensionality on Thermoelectric Device Performance: The role of dimensionality on the electronic performance of thermoelectric\ndevices is clarified using the Landauer formalism, which shows that the\nthermoelectric coefficients are related to the transmission, T(E), and how the\nconducing channels, M(E), are distributed in energy. The Landauer formalism\napplies from the ballistic to diffusive limits and provides a clear way to\ncompare performance in different dimensions. It also provides a physical\ninterpretation of the \"transport distribution,\" a quantity that arises in the\nBoltzmann transport equation approach. Quantitative comparison of\nthermoelectric coefficients in one, two, and three dimension shows that the\nchannels may be utilized more effectively in lower-dimensions. To realize the\nadvantage of lower dimensionality, however, the packing density must be very\nhigh, so the thicknesses of the quantum wells or wires must be small. The\npotential benefits of engineering M(E) into a delta-function are also\ninvestigated. When compared to a bulk semiconductor, we find the potential for\n~50 % improvement in performance. The shape of M(E) improves as dimensionality\ndecreases, but lower dimensionality itself does not guarantee better\nperformance because it is controlled by both the shape and the magnitude of\nM(E). The benefits of engineering the shape of M(E) appear to be modest, but\napproaches to increase the magnitude of M(E) could pay large dividends."
    },
    {
        "anchor": "Size Quantization in Planar Graphene-Based Heterostructures: Pseudospin\n  Splitting, Interface States, and Excitons: A planar quantum-well device made of a gapless graphene nanoribbon with edges\nin contact with gapped graphene sheets is examined. The size-quantization\nspectrum of charge carriers in an asymmetric quantum well is shown to exhibit a\npseudospin splitting. Interface states of a new type arise from the crossing of\ndispersion curves of gapless and gapped graphene materials. The exciton\nspectrum is calculated for a planar graphene quantum well. The effect of an\nexternal electric field on the exciton spectrum is analyzed.",
        "positive": "Shot noise in electron transport through a double quantum dot: A master\n  equation approach: We study shot noise in tunneling current through a double quantum dot\nconnected to two electric leads. We derive two master equations in the\noccupation-state basis and the eigenstate basis to describe the electron\ndynamics. The approach based on the occupation-state basis, despite widely used\nin many previous studies, is valid only when the interdot coupling strength is\nmuch smaller than the energy difference between the two dots. In contrast, the\ncalculations using the eigenstate basis are valid for an arbitrary interdot\ncoupling. We show that the master equation in the occupation-state basis\nincludes only the low-order terms with respect to the interdot coupling\ncompared with the more accurate master equation in the eigenstate basis. Using\nrealistic model parameters, we demonstrate that the predicted currents and\nshot-noise properties from the two approaches are significantly different when\nthe interdot coupling is not small. Furthermore, properties of the shot noise\npredicted using the eigenstate basis successfully reproduce qualitative\nfeatures found in a recent experiment."
    },
    {
        "anchor": "Dissipative and Hall viscosity of a disordered 2D electron gas: We study the dissipative and Hall viscosity of a disordered noninteracting 2D\nelectrons, both analytically and numerically. Analytically, we employ the\nself-consistent Born approximation, explicitly taking into account the\nmodification of the single-particle density of states and the elastic transport\ntime due to the Landau quantization. The reported results interpolate smoothly\nbetween the limiting cases of weak (strong) magnetic field and strong (weak)\ndisorder. In the regime of weak magnetic field, our results describes the\nquantum (de Haas-van Alphen type) oscillations of the dissipative and Hall\nviscosity. For strong magnetic field, we computed the dependence of the\ndissipative and Hall viscosity on disorder broadening of a Landau level. In\nparticular, for the Hall viscosity the effect of the disorder broadening is\nweak. This theoretical conclusion is in agreement with our numerical results\nfor a few lowest Landau levels, which show that Hall viscosity is robust to\ndisorder.",
        "positive": "Incompressible States of the Interacting Composite Fermions in Negative\n  Effective Magnetic Fields at $\u03bd=4/13$, 5/17, and 3/10: By developing an algorithm for evaluating the basis states for the composite\nfermions with negative effective magnetic field, we perform the\ncomposite-fermion-diagonalization study for the fully spin-polarized fractional\nquantum Hall states at the filling factors $\\nu = 3/10$, 4/13, and 5/17 in the\nrange $2/7 <\\nu < 1/3$. These observed states correspond to partially filled\nsecond effective Landau level, for the composite fermions carrying four\nvortices, with filling factor $\\bar{\\nu} = 1/2$, 1/3, and 2/3 respectively,\nanalogous to the previously studied states of composite fermions with two\nattached vortices in the range $1/3 <\\nu <2/5$. We show that the character of\nthese states in the range $2/7 <\\nu < 1/3$ replicates the same for the states\nin the range $1/3 <\\nu <2/5$ having identical $\\bar{\\nu}$: Chiral p-wave\npairing with anti-Pfaffian correlation of composite fermions carrying six\nquantized vortices produces incompressible state at $\\nu = 3/10$; an\nunconventional interaction between composite fermions, resulting from the\nsuppression of fermion pairs with relative angular momentum three and producing\nfractional quantum Hall effect of composite fermions in the second effective\nLandau level with $\\bar{\\nu} =1/3$ and its particle-hole conjugate filling\nfactor 2/3, reproduces incompressible states at $4/13$ and $5/17$ filling\nfactors. We further estimate the thermodynamic limit of the ground state\nenergies and calculate the lowest energy gap for neutral collective excitations\nof these states."
    },
    {
        "anchor": "Orientation of hole quantum Hall nematic phases in an out-of-plane\n  electric field: We present observations of an anisotropic resistance state at Landau level\nfilling factor $\\nu=5/2$ in a two-dimensional hole system (2DHS), which occurs\nfor certain values of hole density $p$ and average out-of-plane electric field\n$E_\\perp$. The 2DHS is induced by electric field effect in an undoped\nGaAs/AlGaAs quantum well, where front and back gates allow independent tuning\nof $p$ and $E_\\perp$, and hence the symmetry of the confining potential. For\n$p\\approx2\\times10^{11}$~cm$^{-2}$ and $E_\\perp \\approx -2 \\times10^{5}$~V/m,\nthe magnetoresistance along $\\langle01\\bar1\\rangle$ greatly exceeds that along\n$\\langle011\\rangle$, suggesting the formation of a quantum Hall nematic or\n`stripe' phase. Reversing the sign of $E_\\perp$ rotates the stripes by\n$90^{\\circ}$. We suggest this behavior may arise from the mixing of the hole\nLandau levels and a combination of the Rashba and Dresselhaus spin-orbit\ncoupling effects.",
        "positive": "Mass-profile quantum dots in graphene: We analyze the bound-state spectra of mass-profile quantum dots in graphene,\na system at current experimental reach. Homogeneous perpendicular magnetic\nfields are also considered which result in breaking the valley degeneracy. The\nspectra show rich features, arising from the chiral band structure of graphene\nand its Landau levels and we identify three different regimes depending on the\nratio between the radius of the dot and the magnetic length. We further carry\nout a comparison with potential-well quantum dots discussed in [Recher et al,\nPhys. Rev. B 79, 085407 (2009)] and conclude that mass confinement may offer\nsignificant advantages for optical applications in the THz and infrared regime.\nAlso due to experimental advances, we additionally analyze the band structure\nof a linear chain of mass-profile quantum dots, where overlap-assisted hopping\nprocesses play a main role for closely packed arrays. Here, the inclusion of\nCoulomb interactions shows that Frenkel excitons can be hosted by the system\nfor certain values of the lattice constant. A Bose-Hubbard model can be\nmimicked under such a choice of the distance between the dots."
    },
    {
        "anchor": "Realization of 5 h/e^2 with graphene quantum Hall resistance array: We report on realization of 10 quantum Hall devices in series fabricated\nusing epitaxial graphene on silicon carbide. Precision measurements with a\nresistance bridge indicates that the quantized Hall resistance across an array\nat filling factor 2 is equivalent to 5 h/e^2 within the measurement uncertainty\nof approximately 4 10-8. A quantum-Hall phase diagram for the array shows that\na metrological quantization of 5 h/e^2 can be achieved at the magnetic field of\n6 T and temperature of 4 K. This experiment demonstrates the possibility of\ntimely unchangeable resistance reference in various ranges in relaxed\nexperimental conditions.",
        "positive": "Enhancement of Fluctuation-Induced Electromagnetic Phenomena in\n  dynamically nonequilibrium systems at Resonant Photon Emission: We study the resonances in Casimir friction, radiative heat transfer and heat\ngeneration for two plates sliding relative to each other. Resonances have a\ndifferent origin in the frequency range of the \\textit{normal} (NDE) and\n\\textit{anomalous} (ADE) Doppler effect. In the frequency range of NDE,\nresonances are associated with resonant photon tunnelling between surface\nphonon/plasmon polaritons of plates. For two identical plates, such resonances\nexist only at a relative sliding velocity $v=0$. However, for different plates\nsuch resonance can exist at $v\\neq 0$. In the frequency range of ADE,\nresonances are associated with the creation of excitations in both plates.\nWhile in the frequency range of NDE the photon emission rate has an upper\nlimit, in the frequency range of ADE, the photon emission rate can diverge even\nin the presence of dissipation in the system. We consider resonances for the\nidentical and different sliding plates. We discuss the possibility to detect\nCasimir friction with its limiting case of quantum friction using an atomic\nforce microscope in graphene structures."
    },
    {
        "anchor": "Spin Berry phase in anisotropic topological insulators: Three-dimensional topological insulators are characterized by the presence of\nprotected gapless spin helical surface states. In realistic samples these\nsurface states are extended from one surface to another, covering the entire\nsample. Generally, on a curved surface of a topological insulator an electron\nin a surface state acquires a spin Berry phase as an expression of the\nconstraint that the effective surface spin must follow the tangential surface\nof real space geometry. Such a Berry phase adds up to pi when the electron\nencircles, e.g., once around a cylinder. Realistic topological insulators\ncompounds are also often layered, i.e., are anisotropic. We demonstrate\nexplicitly the existence of such a pi Berry phase in the presence and absence\n(due to crystal anisotropy) of cylindrical symmetry, that is, regardless of\nfulfilling the spin-to-surface locking condition. The robustness of the spin\nBerry phase pi against cylindrical symmetry breaking is confirmed numerically\nusing a tight-binding model implementation of a topological insulator nanowire\npenetrated by a pi-flux tube.",
        "positive": "Datta-Das transistor: Significance of channel direction, size-dependence\n  of source contacts, and boundary effects: We analyze the spin expectation values for injected spin-polarized electrons\n(spin vectors) in a [001]-grown Rashba-Dresselhaus two-dimensional electron gas\n(2DEG). We generalize the calculation for point spin injection in semi-infinite\n2DEGs to finite-size spin injection in bounded 2DEGs. Using the obtained spin\nvector formula, significance of the channel direction for the Datta-Das\ntransistor is illustrated. Numerical results indicate that the influence due to\nthe finite-size injection is moderate, while the channel boundary reflection\nmay bring unexpected changes. Both effects are concluded to decrease when the\nspin-orbit coupling strength is strong. Hence [110] is a robust channel\ndirection and is therefore the best candidate for the design of the Datta-Das\ntransistor."
    },
    {
        "anchor": "Charge fluctuations in open chaotic cavities: We present a discussion of the charge response and the charge fluctuations of\nmesoscopic chaotic cavities in terms of a generalized Wigner-Smith matrix. The\nWigner-Smith matrix is well known in investigations of time-delay of quantum\nscattering. It is expressed in terms of the scattering matrix and its\nderivatives with energy. We consider a similar matrix but instead of an energy\nderivative we investigate the derivative with regard to the electric potential.\nThe resulting matrix is then the operator of charge. If this charge operator is\ncombined with a self-consistent treatment of Coulomb interaction, the charge\noperator determines the capacitance of the system, the non-dissipative\nac-linear response, the RC-time with a novel charge relaxation resistance, and\nin the presence of transport a resistance that governs the displacement\ncurrents induced into a nearby conductor. In particular these capacitances and\nresistances determine the relaxation rate and dephasing rate of a nearby qubit\n(a double quantum dot). We discuss the role of screening of mesoscopic chaotic\ndetectors. Coulomb interaction effects in quantum pumping and in photon\nassisted electron-hole shot noise are treated similarly. For the latter we\npresent novel results for chaotic cavities with non-ideal leads.",
        "positive": "Superchiral Surface Waves for All-Optical Enantiomer Separation: We introduce the use of superchiral surface waves for the all-optical\nseparation of chiral compounds. Using a combination of electrodynamics modeling\nand analytical techniques, we show that the proposed approach provides chiral\noptical forces two orders of magnitude larger than those obtained with\ncircularly polarized plane waves. Superchiral surface waves allow for\nenantiomer separation on spatial, temporal and size scales than would not be\nachievable with alternative techniques, thus representing a viable route\ntowards all-optical enantiomer separation."
    },
    {
        "anchor": "Nanoscale Mach-Zehnder interferometer with spin-resolved quantum Hall\n  edge states: We realize a nanoscale-area Mach-Zehnder interferometer with co-propagating\nquantum Hall spin-resolved edge states and demonstrate the persistence of\ngate-controlled quantum interference oscillations, as a function of an applied\nmagnetic field, at relatively large temperatures. Arrays of top-gate magnetic\nnanofingers are used to induce a resonant charge transfer between the pair of\nspin-resolved edge states. To account for the pattern of oscillations measured\nas a function of magnetic field and gate voltage, we have developed a simple\ntheoretical model which satisfactorily reproduces the data.",
        "positive": "Finite difference method for Dirac electrons in circular quantum dots: A simple and reliable finite difference approach is presented for solution of\nthe Dirac equation eigenproblem for states confined in rotationally symmetric\nsystems. The method sets the boundary condition for the spinor wave function\ncomponents at the external edge of the system and then sweeps the radial mesh\nin search for the energies for which the boundary conditions are met inside the\nflake. The sweep that is performed from the edge of the system towards the\norigin allows for application of a two-point finite difference quotient of the\nfirst derivative, which prevents the fermion doubling problem and the\nappearance of the spurious solutions with rapid oscillations of the wave\nfunctions in space."
    },
    {
        "anchor": "Integrated quantum polariton interferometry: Exciton-polaritons are hybrid elementary excitations of light and matter\nthat, thanks to their nonlinear properties, enable a plethora of physical\nphenomena ranging from room temperature condensation to superfluidity. While\npolaritons are usually exploited in high density regime, evidence of quantum\ncorrelations at the level of few excitations has been recently reported, thus\nsuggesting the possibility of using these systems for quantum information\npurposes. Here we show that integrated circuits of propagating single\npolaritons can be arranged to build deterministic quantum logic gates in which\nthe two-particle interaction energy plays a crucial role. Besides showing their\nprospective potential for photonic quantum computation, we also show that these\nsystems can be exploited for metrology purposes, as for instance to precisely\nmeasure the magnitude of the polariton-polariton interaction at the two-body\nlevel. In general, our results introduce a novel paradigm for the development\nof practical quantum polaritonic devices, in which the effective interaction\nbetween single polaritonic qubits may provide a unique tool for future quantum\ntechnologies.",
        "positive": "Spontaneous orbital magnetization of mesoscopic dipole dimers: Ensembles of gold nanoparticles present a magnetic behavior which is at odds\nwith the weakly diamagnetic response of bulk gold. In particular, an unusual\nferromagnetic order has been unveiled by several experiments. Here we\ninvestigate if the combined effect of orbital magnetism of conduction electrons\nand interparticle dipolar interaction can lead to magnetic ordering. Using\ndifferent model systems of interacting mesoscopic magnetic dipoles, together\nwith a microscopic description of the electron dynamics within the\nnanoparticles, we find that a spontaneous magnetic moment may arise in dimers\nof metallic nanoparticles when the latter are characterized by a large orbital\nparamagnetic susceptibility."
    },
    {
        "anchor": "On-Demand Generation of Neutral and Negatively-Charged Silicon-Vacancy\n  Centers in Diamond: Point defects in wide-bandgap semiconductors are emerging as versatile\nresources for nanoscale sensing and quantum information science but our\nunderstanding of the photo-ionization dynamics is presently incomplete. Here we\nuse two-color confocal microscopy to investigate the dynamics of charge in Type\n1b diamond hosting nitrogen-vacancy (NV) and silicon-vacancy (SiV) centers. By\nexamining the non-local fluorescence patterns emerging from local laser\nexcitation, we show that in the simultaneous presence of photo-generated\nelectrons and holes, SiV (NV) centers selectively transform into the negative\n(neutral) charge state. Unlike NVs, 532 nm illumination ionizes SiV- via a\nsingle photon process thus hinting at a comparatively shallower ground state.\nIn particular, slower ionization rates at longer wavelengths suggest the latter\nlies approximately ~1.9 eV below the conduction band minimum. Building on the\nabove observations we demonstrate on-demand SiV and NV charge initialization\nover large areas via green laser illumination of variable intensity.",
        "positive": "Non-Local Correlations in Normal Metal-Superconducting Systems: We examine nonlocal effects between normal-metal gold probes connected by\nsuperconducting aluminum. For highly transparent Au/Al interfaces, we find\nnonlocal voltages that obey a spatial and temperature evolution distinct from\nthe nonequilibrium charge imbalance signals usually found in such systems.\nThese voltages are consistent with the predicted effects of crossed Andreev\nreflection and elastic cotunneling, effects that involve coherent correlations\nbetween spatially separated electrons."
    },
    {
        "anchor": "Zone-Boundary Phonon Induced Mini Band Gap Formation in Graphene: We investigate the effect of electron- $\\mathrm{A}_{1g}$ phonon coupling on\nthe gapless electronic band dispersion of the pristine graphene. The\nelectron-phonon interaction is introduced through a Kekul\\'{e}-type distortion\ngiving rise to inter-valley scattering between K and K' points in graphene. We\ndevelop a Fr\\\"ohlich type Hamiltonian within the continuum model in the long\nwave length limit. By presenting a fully theoretical analysis, we show that the\ninteraction of charge carriers with the highest frequency zone-boundary phonon\nmode of $% \\mathrm{A}_{1g}$-symmetry induces a mini band gap at the corners of\nthe two-dimensional Brillouin zone of the graphene. Since electron-electron\ninteractions favor this type of lattice distortion, it is expected to be\nenhanced, and thus its quantitative implications might be measurable in\ngraphene.",
        "positive": "Faraday Rotation, Band Splitting, and One-Way Propagation of Plasmon\n  Waves on a Nanoparticle Chain: We calculate the dispersion relations of plasmonic waves propagating along a\nchain of semiconducting or metallic nanoparticles in the presence of both a\nstatic magnetic field ${\\bf B}$ and a liquid crystalline host. The dispersion\nrelations are obtained using the quasistatic approximation and a dipole-dipole\napproximation to treat the interaction between surface plasmons on different\nnanoparticles. For a plasmons propagating along a particle chain in a nematic\nliquid crystalline host with both ${\\bf B}$ and the director parallel to the\nchain, we find a small, but finite, Faraday rotation angle. For ${\\bf B}$\nperpendicular to the chain, but director still parallel to the chain, the field\ncouples the longitudinal and one of the two transverse plasmonic branches. This\ncoupling is shown to split the two branches at the zero field crossing by an\namount proportional to $|{\\bf B}|$. In a cholesteric liquid crystal host and an\napplied magnetic field parallel to the chain, the dispersion relations for\nleft- and right-moving waves are found to be different. For some frequencies,\nthe plasmonic wave propagates only in one of the two directions."
    },
    {
        "anchor": "Activated hopping transport in nematic conducting aerogel at low\n  temperatures: The transport properties of nematic aerogels, which consist of highly\noriented Al$_2$O$_3\\cdot$SiO$_2$ nanofibers coated with a graphene shell with a\nlarge number of defects, are studied. The temperature dependences of the\nelectrical resistivity in the range of 9-40K strictly follow the formula\nderived to describe the variable range hopping (VRH) conductivity, in which\nexponent $\\alpha$ changes from 0.4 to 0.9 when the number of layers in the\ngraphene shell decreases from 4-6 to 1-2. The dependence of $\\alpha$ on the\nshell thickness can be explained by a simultaneous change in the dimensionality\nof hopping transport and the character of the energy dependence of the density\nof localized states near the Fermi level. The fact that $\\alpha$ approaches\nunity at the minimum graphene shell thickness indicates a gradual transition\nfrom VRH transport to nearest neighbor hopping (NNH) transport. The\nmagnetoresistance measured at T = 4.2 K is negative, increases significantly\nwith decreasing graphene shell thickness, and is approximated by a formula for\nthe case of weak localization with a good accuracy. The phase coherence lengths\nare in a reasonable relation with the graphene grain sizes. The conducting\naerogels under study complement the well-known set of materials that exhibit\nhopping electron transport at low temperatures, which is characteristic of\nmedia with strong carrier localization, and also a negative magnetoresistance,\nwhich usually manifests itself under weak localization conditions.",
        "positive": "Magneto Acoustic Spin Hall Oscillators: This paper introduces a novel oscillator that combines the tunability of spin\nHall-driven nano oscillators with the high quality factor (Q) of high overtone\nbulk acoustic wave resonators (HBAR), integrating both reference and tunable\noscillators on the same chip with CMOS. In such magneto acoustic spin Hall\n(MASH) oscillators, voltage oscillations across the magnetic tunnel junction\n(MTJ) that arise from a spin-orbit torque (SOT) are shaped by the transmission\nresponse of the HBAR that acts as a multiple peak-bandpass filter and a delay\nelement due to its large time constant, providing delayed feedback. The\nfiltered voltage oscillations can be fed back to the MTJ via a) strain, b)\ncurrent, or c) magnetic field. We develop a SPICE-based circuit model by\ncombining experimentally benchmarked models including the stochastic\nLandau-Lifshitz-Gilbert (sLLG) equation for magnetization dynamics and the\nButterworth Van Dyke (BVD) circuit for the HBAR. Using the self-consistent\nmodel, we project up to $\\sim$ 50X enhancement in the oscillator linewidth with\nQ reaching up to 52825 at 3 GHz, while preserving the tunability by locking the\nSTNO to the nearest high Q peak of the HBAR. We expect that our results will\ninspire MEMS-based solutions to spintronic devices by combining attractive\nfeatures of both fields for a variety of applications."
    },
    {
        "anchor": "Atomic collapse in graphene and cyclic RG flow: In this Letter we consider the problem of screening of external charge in\ngraphene from the cyclic RG flow viewpoint. The analogy with conformal Calogero\nmodel is used to suggest the interpretation of the tower of resonant states as\ntower of Efimov states.",
        "positive": "Reduction of the Twisted Bilayer Graphene Chiral Hamiltonian into a\n  $2\\times2$ matrix operator and physical origin of flat-bands at magic angles: The chiral Hamiltonian for twisted graphene bilayers is written as a\n$2\\times2$ matrix operator by a renormalization of the Hamiltonian that takes\ninto account the particle-hole symmetry. This results in an effective\nHamiltonian with an average field plus and effective non-Abelian gauge\npotential. The action of the proposed renormalization maps the zero-mode region\ninto the ground state. Modes near zero energy have an antibonding nature in a\ntriangular lattice. This leads to a phase-frustration effect associated with\nmassive degeneration, and makes flat-bands modes similar to confined modes\nobserved in other bipartite lattices. Suprisingly, the proposed Hamiltonian\nrenormalization suggests that flat-bands at magic angles are akin to\nfloppy-mode bands in flexible crystals or glasses, making an unexpected\nconnection between rigidity topological theory and magic angle twisted\ntwo-dimensional heterostructures physics."
    },
    {
        "anchor": "A minimal, \"hydrogen atom\" version of an inversion-breaking Weyl\n  semimetal: The recent explosion of research interest in Weyl semimetals has led to many\nproposed Weyl semimetal candidates and a few experimental observations of a\nWeyl semimetal in real materials. Through this experience, we have come to\nappreciate that typical Weyl semimetals host many Weyl points. For instance,\nthe first Weyl semimetal observed in experiment, TaAs, hosts 24 Weyl points.\nSimilarly, the Mo$_x$W$_{1-x}$Te$_2$ series, recently under study as the first\nType II Weyl semimetal, has eight Weyl points. However, it is well-understood\nthat for a Weyl semimetal without inversion symmetry but with time-reversal\nsymmetry, the minimum number of Weyl points is four. Realizing such a minimal\nWeyl semimetal is fundamentally relevant because it would offer the simplest\n\"hydrogen atom\" example of an inversion-breaking Weyl semimetal. At the same\ntime, transport experiments and device applications may be simpler in a system\nwith as few Weyl points as possible. Recently, TaIrTe$_4$ has been predicted to\nbe a minimal, inversion-breaking Weyl semimetal. However, crucially, the Weyl\npoints and Fermi arcs live entirely above the Fermi level, making them\ninaccessible to conventional angle-resolved photoemission spectroscopy (ARPES).\nHere we use pump-probe ARPES to directly access the band structure above the\nFermi level in TaIrTe$_4$. We directly observe Weyl points and topological\nFermi arcs, showing that TaIrTe$_4$ is a Weyl semimetal. We find that, in\ntotal, TaIrTe$_4$ has four Weyl points, providing the first example of a\nminimal inversion-breaking Weyl semimetal. Our results hold promise for\naccessing exotic transport phenomena arising in Weyl semimetals in a real\nmaterial.",
        "positive": "Fermi arc plasmons in Weyl semimetals: In the recently discovered Weyl semimetals, the Fermi surface may feature\ndisjoint, open segments -- the so-called Fermi arcs -- associated with\ntopological states bound to exposed crystal surfaces. Here we show that the\ncollective dynamics of electrons near such surfaces sharply departs from that\nof a conventional three-dimensional metal. In magnetic systems with broken time\nreversal symmetry, the resulting Fermi arc plasmons (FAPs) are chiral, with\ndispersion relations featuring open, hyperbolic constant frequency contours. As\na result, a large range of surface plasmon wave vectors can be supported at a\ngiven frequency, with corresponding group velocity vectors directed along a few\nspecific collimated directions. Fermi arc plasmons can be probed using near\nfield photonics techniques, which may be used to launch highly directional,\nfocused surface plasmon beams. The unusual characteristics of FAPs arise from\nthe interplay of bulk and surface Fermi arc carrier dynamics, and give a window\ninto the unusual Fermiology of Weyl semimetals."
    },
    {
        "anchor": "Signatures of two-level defects in the temperature-dependent damping of\n  nanomechanical silicon nitride resonators: The damping rates of high quality factor nanomechanical resonators are well\nbeyond intrinsic limits. Here, we explore the underlying microscopic loss\nmechanisms by investigating the temperature-dependent damping of the\nfundamental and third harmonic transverse flexural mode of a doubly clamped\nsilicon nitride string. It exhibits characteristic maxima reminiscent of\ntwo-level defects typical for amorphous materials. Coupling to those defects\nrelaxes the momentum selection rules, allowing energy transfer from discrete\nlong wavelength resonator modes to the high frequency phonon environment.",
        "positive": "Magnetic field-tuned Aharonov-Bohm oscillations and evidence for\n  non-Abelian anyons at v=5/2: We show that the resistance of the v=5/2 quantum Hall state, confined to an\ninterferometer, oscillates with magnetic field consistent with an Ising-type\nnon-Abelian state. In three quantum Hall interferometers of different sizes,\nresistance oscillations at v=7/3 and integer filling factors have the magnetic\nfield period expected if the number of quasiparticles contained within the\ninterferometer changes so as to keep the area and the total charge within the\ninterferometer constant. Under these conditions, an Abelian state such as the\n(3,3,1) state would show oscillations with the same period as at an integer\nquantum Hall state. However, in an Ising-type non-Abelian state there would be\na rapid oscillation associated with the \"even-odd effect\" and a slower one\nassociated with the accumulated Abelian phase due to both the Aharonov-Bohm\neffect and the Abelian part of the quasiparticle braiding statistics. Our\nmeasurements at v=5/2 are consistent with the latter."
    },
    {
        "anchor": "Green's function for metamaterial superlens: Evanescent wave in the\n  image: We develop a new method to calculate the evanescent wave, the subdivided\nevanescent waves (SEWs), and the radiative wave, which can be obtained by\nseparating the global field of the image of metamaterial superlens. The method\nis based on Green's function, and it can be applied in other linear systems.\nThis study could help us to investigate the effect of evanescent wave on\nmetamaterial superlens directly, and give us a new way to design new devices.",
        "positive": "Magnetic Field Induced Weyl Semimetal from Wannier-Function-based\n  Tight-Binding Model: Weyl semimetals (WSMs) have Weyl nodes where conduction and valence bands\nmeet in the absence of inversion or time-reversal symmetry (TRS), or both.\nInteresting phenomena are expected in WSMs such as the chiral magnetic effect,\nanomalous Hall conductivity or Nernst effect, and unique quantum oscillations.\nThe TRS-broken WSM phase can be driven from a topological Dirac semimetal (DSM)\nby magnetic field or magnetic dopants, considering that DSMs have degenerate\nWeyl nodes stabilized by rotational symmetry, i.e. Dirac nodes. Here we develop\na Wannier-function-based tight-binding (WF-TB) model to investigate the\nformation of Weyl nodes and nodal rings induced by B field in the topological\nDSM Na$_3$Bi. The field is applied along the rotational axis. Remarkably, our\nstudy based on the WF-TB model shows that upon B field each Dirac node is split\ninto four separate Weyl nodes along the rotational axis near the Fermi level;\ntwo nodes with single chiral charge (single Weyl nodes) and two with double\nchiral charge (double Weyl nodes). This result is in contrast to the common\nbelief that each Dirac node splits into two Weyl nodes. In the effective\nmodels, the existence of double Weyl nodes ensures nonzero cubic terms in\nmomentum. We further examine the evolution of Fermi arcs at a side surface as a\nfunction of chemical potential. The number of Fermi arcs is consistent with the\ncorresponding Fermi surface Chern numbers, corroborating our finding of the\ndouble Weyl nodes. Furthermore, our study reveals the existence of nodal rings\nin the mirror plane below the Fermi level upon B field. These nodal rings\npersist with spin-orbit coupling, in contrast to typical nodal ring semimetals.\nOur WF-TB model can be used to compute interesting features arising from Berry\ncurvature such as anomalous Hall and thermal conductivities, and our findings\ncan be applied to other topological DSMs like Cd$_3$As$_2$."
    },
    {
        "anchor": "Hall field-induced magneto-oscillations near charge neutrality point in\n  graphene: We explore the non-equilibrium transport regime in graphene using a large dc\ncurrent in combination with a perpendicular magnetic field. The strong in-plane\nHall field that is generated in the bulk of the graphene channel results in\nLandau levels that are tilted spatially. The energy of cyclotron orbits in the\nbulk varies as a function of the spatial position of the guiding center,\nenabling us to observe a series of compelling features. While Shubnikov-de Haas\noscillations are predictably suppressed in the presence of the Hall field, a\nset of fresh magnetoresistance oscillations emerge near the charge neutrality\npoint as a function of dc current. Two branches of oscillations with linear\ndispersions are evident as we vary carrier density and dc current, the velocity\nof which closely resembles the TA and LA phonon modes, suggestive of\nphonon-assisted intra-Landau level transitions between adjacent cyclotron\norbits. Our results offer unique possibilities to explore non-equilibrium\nphenomena in two-dimensional materials and van der Waals heterostructures.",
        "positive": "Many-body corrections to ESR energy and spin-wave excitations in\n  two-dimensional systems with Bychkov-Rashba spin splitting: We report effects of electron-electron (\\emph{e-e}) interaction on electron\nspin resonance (ESR) in perpendicular magnetic field in two-dimensional (2D)\nsystems with Bychkov-Rashba spin splitting induced by spin-orbit interaction\n(SOI) and structural inversion asymmetry (SIA). Using the Hartree-Fock\napproximation, we demonstrate that the SIA results in non-zero many-body\ncorrections to the ESR energy and the energy of spin wave excitations. We\ndiscover that the \\emph{e-e} interaction in 2D systems with SIA not only can\nenhance the ESR energy but can also lead to the ESR energy reduction. The\nmagnitude of this effect exhibits remarkable features in a wide range of\nparameters relevant to experiment: it is found to be rather sensitive to the\nsign of g-factor and the filling factor of Landau levels $\\nu$. We derive\nanalytical expressions for many-body corrections to ESR energy and the\ndispersion of spin wave excitations for the case of $\\nu\\leq 2$. We have found\nout that \\emph{e-e} interaction does not affect the ESR energy in the case of\nfilling of the lowest Landau level ($\\nu\\leq 1$) in 2D systems with positive\ng-factors even at arbitrarily large values of Bychkov-Rashba constant. The\nmany-body renormalization of ESR energy in the case of fractional Quantum Hall\neffect is also discussed."
    },
    {
        "anchor": "Two Kinds of the Coexistent States in One-Dimensional Quarter -Filled\n  Systems under Magnetic Fields: The coexistent state of the spin density wave (SDW) and the charge density\nwave (CDW) in the one-dimensional quarter-filled system and with the Coulomb\ninteraction up to the next-nearest sites under magnetic fields is studied. It\nis found that, in the coexistent state of $2k_{\\rm F}$-SDW and $2k_{\\rm\nF}$-CDW, the charge order is suppressed and $2k_{\\rm F}$-SDW changes to\n$2k_{\\rm F}$-SDW having the different alignment of spin under high magnetic\nfields, whereas, in the coexistent state of $2k_{\\rm F}$-SDW and $4k_{\\rm\nF}$-CDW, $4k_{\\rm F}$-CDW still remains and $2k_{\\rm F}$-SDW is suppressed. The\ncritical temperature of the charge order is higher than that of the spin order\nwhen the inter-site Coulomb interaction is strong. These will be observed in\nexperiments such as the X-ray scattering measurement and NMR.",
        "positive": "$\\textit{Ab initio}$ study of electron mean free paths and\n  thermoelectric properties of lead telluride: Last few years have witnessed significant enhancement of thermoelectric\nfigure of merit of lead telluride (PbTe) via nanostructuring. Despite the\nexperimental progress, current understanding of the electron transport in PbTe\nis based on either band structure calculation using first principles with\nconstant relaxation time approximation or empirical models, both relying on\nadjustable parameters obtained by fitting experimental data. Here, we report\nparameter-free first-principles calculation of electron and phonon transport\nproperties of PbTe, including mode-by-mode electron-phonon scattering analysis,\nleading to detailed information on electron mean free paths and the\ncontributions of electrons and phonons with different mean free paths to\nthermoelectric transport properties in PbTe. Such information will help to\nrationalize the use and optimization of nanosctructures to achieve high\nthermoelectric figure of merit."
    },
    {
        "anchor": "Interference of diffusing photons and level crossing spectroscopy: We show that a new interference effect appears in the intensity fluctuations\nof photons multiply scattered by an atomic gas of large optical depth b. This\ninterference occurs only for scattering atoms that are Zeeman degenerate and it\nleads to a deviation from the Rayleigh law. The fluctuations measured by their\nvariance, display a resonance peak as a function of an applied magnetic field.\nThe resonance width is proportional to the small factor 1/b. We derive closed\nanalytic expressions for all these physical quantities which are directly\naccessible experimentally.",
        "positive": "Magnetoexcitons and optical absorption of bilayer-structured topological\n  insulators: Optical absorption properties of magnetoexcitons in topological insulator\nbilayers under a strong magnetic field are theoretically studied. A general\nanalytical formula of optical absorption selection rule is obtained in the\nnoninteracting as well as Coulomb intra-Landau-level interacting cases, which\nremarkably helps to interpret the resonant peaks in absorption spectroscopy and\nthe corresponding formation of Dirac-type magnetoexcitons. We also discuss the\noptical absorption spectroscopy of magnetoexcitons in the presence of\ninter-Landau-level Coulomb interaction, which becomes more complex. Our results\ncould be detected in the magneto-optical experiments."
    },
    {
        "anchor": "Quantum dot state initialization by control of tunneling rates: We study the loading of electrons into a quantum dot with dynamically\ncontrolled tunnel barriers. We introduce a method to measure tunneling rates\nfor individual discrete states and to identify their relaxation paths.\nExponential selectivity of the tunnel coupling enables loading into specific\nquantum dot states by tuning independently energy and rates. While for the\nsingle-electron case orbital relaxation leads to fast transition into the\nground state, for electron pairs triplet-to-singlet relaxation is suppressed by\nlong spin-flip times. This enables the fast gate-controlled initialization of\neither a singlet or a triplet electron pair state in a quantum dot with broad\npotential applications in quantum technologies.",
        "positive": "Quantum circuits with multiterminal Josephson-Andreev junctions: We explore superconducting quantum circuits where several leads are\nsimultaneously connected beyond the tunneling regime, such that the fermionic\nstructure of Andreev bound states in the resulting multiterminal Josephson\njunction influences the states of the full circuit. Using a simple model of\nsingle channel contacts and a single level in the middle region, we discuss\ndifferent circuit configurations where the leads are islands with finite\ncapacitance and/or form loops with finite inductance. We find situations of\npractical interest where the circuits can be used to define noise protected\nqubits, which map to the bifluxon and $0{-}\\pi$ qubits in the tunneling regime.\nWe also point out the subtleties of the gauge choice for a proper description\nof these quantum circuits dynamics."
    },
    {
        "anchor": "Mesoscopic proximity effect in double barrier Superconductor/Normal\n  Metal junctions: We report transport measurements down to T=60mK of SININ and SNIN structures\nin the diffusive limit. We fabricated Al-AlOx/Cu/AlOx/Cu (SININ) and\nAl/Cu/AlOx/Cu (SNIN) vertical junctions. For the first time, a zero bias\nanomaly was observed in a metallic SININ structure. We attribute this peak of\nconductance to coherent multi-reflections of electrons between the two tunnel\nbarriers. This conductance maximum is quantitatively fitted by the relevant\ntheory of mesoscopic SININ structures. When the barrier at the SN interface is\nremoved (SNIN structure), we observe a peak of conductance at finite voltage\naccompagnied by an excess of sub-gap conductance.",
        "positive": "Concomitant opening of a topological bulk-gap with an emerging Majorana\n  edge-state: Majorana 'zero-modes' are expected to be immune to decoherence. The primary\nmethod for their characterization in a 1D topological superconductor, is\nmeasuring the tunneling current into the edge of the superconductor. Presently,\nthe hallmark of a localized Majorana edge-state is an emergent quantized\nzero-bias conductance peak (ZBCP). However, such a conductance peak can also\nresult from other mechanisms; e.g., crossing (and sticking) of two branches of\na standard Andreev bound state, or a soft potential at the edge of the\nsuperconductor. Since the emergence of a 'Majorana-ZBCP' must be accompanied by\nan opening of a topological gap in the bulk, we performed two simultaneous\ntunneling measurements: one in the bulk and another at the edge of the 1D\nsuperconductor. Measurements were performed with an InAs nanowire in-situ\ncoated with epitaxial aluminum. For particular gate-tuning of the chemical\npotential in the wire and a Zeeman field parallel to the wire, we observed a\nclosing of the superconducting bulk-gap followed by its reopening concomitant\nwith the appearance of a ZBCP at the edge. We note that a ZBCP could also be\nobserved with different tuning parameters without an observed reopening of the\nbulk-gap. This demonstrates the importance of simultaneous probing of the bulk\nand edge when searching for a Majorana edge-state."
    },
    {
        "anchor": "Current measurement by real-time counting of single electrons: The fact that electrical current is carried by individual charges has been\nknown for over 100 years, yet this discreteness has not been directly observed\nso far. Almost all current measurements involve measuring the voltage drop\nacross a resistor, using Ohm's law, in which the discrete nature of charge does\nnot come into play. However, by sending a direct current through a\nmicroelectronic circuit with a chain of islands connected by small tunnel\njunctions, the individual electrons can be observed one by one. The quantum\nmechanical tunnelling of single charges in this one-dimensional array is time\ncorrelated, and consequently the detected signal has the average frequency\nf=I/e, where I is the current and e is the electron charge. Here we report a\ndirect observation of these time-correlated single-electron tunnelling\noscillations, and show electron counting in the range 5 fA-1 pA. This\nrepresents a fundamentally new way to measure extremely small currents, without\noffset or drift. Moreover, our current measurement, which is based on electron\ncounting, is self-calibrated, as the measured frequency is related to the\ncurrent only by a natural constant.",
        "positive": "Magnitude of the Current in Two-Dimensional Interlayer Tunneling Devices: Using the Bardeen tunneling method with first-principles wave functions,\ncomputations are made of the tunneling current in graphene /\nhexagonal-boron-nitride / graphene (G/h-BN/G) vertical structures. Detailed\ncomparison with prior experimental results is made, focusing on the magnitude\nof the achievable tunnel current. With inclusion of the effects of\ntranslational and rotational misalignment of the graphene and the h-BN,\npredicted currents are found to be about 15x larger than experimental values. A\nreduction in this discrepancy, to a factor of 2.5x, is achieved by utilizing a\nrealistic size for the band gap of the h-BN, hence affecting the exponential\ndecay constant for the tunneling."
    },
    {
        "anchor": "Controlling 3D spin textures by manipulating sign and amplitude of\n  interlayer DMI with electrical current: The recently discovered interlayer Dzyaloshinskii-Moriya interaction (IL-DMI)\nin multilayers with perpendicular magnetic anisotropy favors the canting of\nspins in the in-plane direction and could thus enable new exciting spin\ntextures such as Hopfions in continuous multilayer films. A key requirement is\nto control the IL-DMI and so in this study, the influence of an electric\ncurrent on the IL-DMI is investigated by out-of-plane hysteresis loops of the\nanomalous Hall effect under applied in-plane magnetic fields. The direction of\nthe in-plane field is varied to obtain a full azimuthal dependence, which\nallows us to quantify the effect on the IL-DMI. We observe a shift in the\nazimuthal dependence of the IL-DMI with increasing current, which can be\nunderstood from the additional in-plane symmetry breaking introduced by the\ncurrent flow. Using an empirical model of two superimposed cosine functions we\ndemonstrate the presence of a current-induced term that linearly increases the\nIL-DMI in the direction of current flow. With this, a new easily accessible\npossibility to manipulate 3D spin textures by current is realized. As most\nspintronic devices employ spin-transfer or spin-orbit torques to manipulate\nspin textures, the foundation to implement current-induced IL-DMI into\nthin-film devices is broadly available.",
        "positive": "Size distribution of Au NPs generated by laser ablation of a gold target\n  in liquid with time-delayed femtosecond pulses: The influence of delay-time between two sequential femtosecond pulses on the\nproperties of nanoparticles obtained via laser ablation of gold in ethanol has\nbeen studied. The morphological and optical properties of the nanoparticles\nattained were characterized using high resolution transmission electron\nmicroscopy and UV_Vis absorption spectroscopy, respectively. Furthermore, the\nsize distribution of nanoparticles was determined by means of a centrifugal\nsedimentation particle size analyzer. It is found that the time delay\nvariations lead to corresponding changes in size distribution, plasmon\nresonance position as well as the rate of nanoparticles generation."
    },
    {
        "anchor": "Observing visible-range photoluminescence in GaAs nanowires modified by\n  laser irradiation: We study structural and chemical transformations induced by focused laser\nbeam in GaAs nanowires with axial zinc-blende/wurtzite (ZB/WZ) heterostucture.\nThe experiments are performed using a combination of transmission electron\nmicroscopy, energy-dispersive X-ray spectroscopy, Raman scattering, and\nphotoluminescence spectroscopy. For the both components of heterostructure,\nlaser irradiation under atmospheric air is found to produce a double surface\nlayer which is composed of crystalline arsenic and of amorphous GaO$_{x}$. The\nlatter compound is responsible for appearance of a peak at 1.76 eV in\nphotoluminescence spectra of GaAs nanowires. Under increased laser power\ndensity, due to sample heating, evaporation of the surface crystalline arsenic\nand formation of $\\beta$-Ga$_{2}$O$_{3}$ nanocrystals proceed on surface of the\nzinc-blende part of nanowire. The formed nanocrystals reveal a\nphotoluminescence band in visible range of 1.7-2.4 eV. At the same power\ndensity for wurtzite part of the nanowire, total amorphization with formation\nof $\\beta$-Ga$_{2}$O$_{3}$ nanocrystals occurs. Observed transformation of\nWZ-GaAs to $\\beta$-Ga$_{2}$O$_{3}$ nanocrystals presents an available way for\ncreation of axial and radial heterostuctures ZB-GaAs/$\\beta$-Ga$_{2}$O$_{3}$\nfor optoelectronic and photonic applications.",
        "positive": "Switching of magnon parametric oscillation by magnetic field direction: Parametric oscillation occurs when the resonance frequency of an oscillator\nis periodically modulated. Owing to time-reversal symmetry breaking in magnets,\nnonreciprocal magnons can be parametrically excited when spatial-inversion\nsymmetry breaking is provided. This means that magnons with opposite\npropagation directions have different amplitudes. Here we demonstrate switching\non and off the magnon parametric oscillation by reversing the external field\ndirection applied to a Y$_3$Fe$_5$O$_{12}$ micro-structured film. The result\noriginates from the nonreciprocity of surface mode magnons, leading to\nfield-direction dependence of the magnon accumulation under a nonuniform\nmicrowave pumping. Our numerical calculation well reproduces the experimental\nresult."
    },
    {
        "anchor": "Resonance energy transfer near metal nanostructures mediated by surface\n  plasmons: We develop a unified theory of plasmon-assisted resonance energy transfer\n(RET) between molecules near a metal nanostructure that maintains energy\nbalance between transfer, dissipation, and radiation. We show that in a wide\nrange of parameters, including in the near field, RET is dominated by\nplasmon-enhanced radiative transfer (PERT) rather than by a nonradiative\ntransfer mechanism. Our numerical calculations performed for molecules near the\nAg nanoparticle indicate that RET magnitude is highly sensitive to molecules'\npositions.",
        "positive": "Symmetry breaking and (pseudo)spin polarization in Veselago lenses for\n  massless Dirac fermions: We study Veselago lensing of massless Dirac fermions by n-p junctions for\nelectron sources with a certain polarization. This polarization corresponds to\npseudospin for graphene and to real spin for topological insulators. Both for a\npoint source and for injection into a sample through a narrow lead, we find\nthat polarization leads to spatial symmetry breaking. For the Green's function,\nthis results in a vertical displacement, or even complete vanishing of the main\nfocus, depending on the exact polarization. For injection through a lead, it\nleads to a difference between the amounts of current emitted with positive and\nnegative transversal momenta. We study both systems in detail using the\nsemiclassical approximation. By comparing the results to the exact solutions,\nwe establish that semiclassical methods provide a very effective way to study\nthese systems. For the Green's function, we derive an easy-to-use analytical\nformula for the vertical displacement of the main focus. For current injection\nthrough a lead, we use semiclassical methods to identify two different\nscattering regimes."
    },
    {
        "anchor": "Electronic transport through a contact of a correlated quantum wire with\n  leads of higher dimension: We study theoretically electronic transport through a contact of a quantum\nwire with 2D or 3D leads and find that if the contact is not smooth and\nadiabatic then the conduction is strongly suppressed below a threshold voltage\n$V_T$, while above $V_T$ the dc current $\\bar I$ is accompanied by coherent\noscillations of frequency $f=\\bar I / e$. The effect is related to\ninterelectronic repulsion and interaction of dc current with the Friedel\noscillations near a sharp contact. In short conducting channels of length $L <\nL_0 \\simeq \\hbar v_F/eV_T$ and at high temperatures $T > T_0 \\simeq eV_T/k_B$\nthe effect is destroyed by fluctuations.",
        "positive": "Localized Magnetic States in 2D Semiconductors: We study the formation of magnetic states in localized impurities embedded\ninto two-dimensional semiconductors. By considering various energy\nconfigurations, we illustrate the interplay of the gap and the bands in the\nsystem magnetization. Finally, we consider finite-temperature effects to show\nhow increasing $T$ can lead to formation and destruction of magnetization."
    },
    {
        "anchor": "NMR lineshape in Metallic Nanoparticles: a Matrix Continued Fraction\n  evaluation: In metallic nanoparticles, the different electronic environment seen by each\nmagnetic nucleus produces a distribution of Knight shifts of the NMR\nfrequencies which is observed as an inhomogeneously broadened lineshape. We\nstudy the fluctuations in the local density of states for s electrons at the\nFermi energy in a simple LCAO model. We resort to a Matrix Continued Fractions\ncalculation of the Green's functions. Results show that line broadens\nasymmetrically and its shift decreases as the particle size or the temperature\ndiminish satisfying a universal scaling function. However, for very small\nparticles, surface states become relevant to determine a lineshape that departs\nfrom the universal scaling behavior. These trends are consistent with the\nobserved tendencies in Cu and Pt particles.",
        "positive": "Strongly coupled single quantum dot-cavity system integrated on a\n  CMOS-processed silicon photonic chip: Quantum photonic integrated circuit (QPIC) is a promising tool for\nconstructing integrated devices for quantum technology applications. In the\noptical regime, silicon photonics empowered by\ncomplementary-metal-oxide-semiconductor (CMOS) technology provides optical\ncomponents useful for realizing large-scale QPICs. Optical nonlinearity at the\nsingle-photon level is required for QPIC to facilitate photon-photon\ninteraction. However, to date, realization of optical elements with\ndeterministic( i.e., not probabilistic) single-photon nonlinearity by using\nsilicon-based components is challenging, despite the enhancement of the\nfunctionality of QPICs based on silicon photonics. In this study, we realize\nfor the first time a strongly coupled InAs/GaAs quantum dot-cavity quantum\nelectrodynamics (QED) system on a CMOS-processed silicon photonic chip. The\nheterogeneous integration of the GaAs cavity on the silicon chip is performed\nby transfer printing. The cavity QED system on the CMOS photonic chip realized\nin this work is a promising candidate for on-chip single-photon nonlinear\nelement, which constitutes the fundamental component for future applications\nbased on QPIC, such as, coherent manipulation and nondestructive measurement of\nqubit states via a cavity, and efficient single-photon filter and router."
    },
    {
        "anchor": "Proposal and design of a new SiC-emitter lateral NPM Schottky collector\n  bipolar transistor on SOI for VLSI applications: A novel bipolar transistor structure, namely, a SiC emitter lateral NPM\nSchottky collector bipolar transistor (SCBT) with a silicon-on-insulator (SOI)\nsubstrate is explored using two-dimensional (2-D) simulation. A comprehensive\ncomparison of the proposed structure with its equivalent Si lateral NPN BJT and\nan SiC emitter lateral NPN HBT is presented. Based on simulation results, the\nauthors demonstrate for the first time that the proposed SiC emitter lateral\nNPM transistor shows superior performance in terms of high current gain and\ncut-off frequency, reduced collector resistance, negligible reverse recovery\ntime and suppressed Kirk effect over its equivalent Si lateral NPN BJT and SiC\nemitter lateral NPN HBT. A simple fabrication process compatible with BiCMOS\ntechnology is also discussed.",
        "positive": "Determination of the Dzyaloshinskii-Moriya interactions: Using in-plane field dependence of the precessional flow of chiral domain\nwalls (DWs) to simultaneously determine bulk and interfacial\nDzyaloshinskii-Moriya interactions (DMIs) is proposed. It is found that\neffective fields of bulk and interfacial DMIs have respectively transverse and\nlongitudinal components that affect differently the motion of chiral DWs in\nmagnetic narrow heterostructure strips. The in-plane field dependence of DW\nvelocity has a dome-shape or a canyon-shape, depending on whether the driving\nforce is an in-plane current or an out-of-plane magnetic field. The responses\nof their center shifts to the reversal of topological wall charge and\ncurrent/field direction uniquely determine the nature and strength of DMI\ntherein. Operable procedures are proposed and applied to explain existing\nexperimental data."
    },
    {
        "anchor": "Chiral Phonons in Moir\u00e9 Superlattices: We discover chiral phonons at the lowest-energy bands in moir\\'e\nsuperlattices. The moir\\'e chiral phonons we uncover are the collective\nexcitations of the stacking domains. Their origin is uniquely attributed to the\nstacking configurations whose interlayer binding energy breaks the $C_{2z}$\nsymmetry on the moir\\'e length scale. Within elastic theory, we use a general\nsymmetry analysis to provide a complete classification of van der Waals\nheterostructures in respect to hosting moir\\'e chiral phonons and show the\ncalculation for twisted MoS$_2$ as an example. We present a low-energy\neffective model to qualitatively understand the moir\\'e chiral phonons and show\nthat it captures the essential physics remarkably well. Our result potentially\nopens up new possibilities in phononic twistronics as the moir\\'e chiral\nphonons have high tunability, moir\\'e scale wavelengths, excitation energies in\nonly a few meV, and can possibly be mechanically excited.",
        "positive": "Reconstruction of the polarization distribution of the Rice-Mele model: We calculate the gauge invariant cumulants (and moments) associated with the\nZak phase in the Rice-Mele model. We reconstruct the underlying probability\ndistribution by maximizing the information entropy and applying the moments as\nconstraints. When the Wannier functions are localized within one unit cell, the\nprobability distribution so obtained corresponds to that of the Wannier\nfunction. We show that in the fully dimerized limit the magnitude of the\nmoments are all equal. In this limit, if the on-site interaction is decreased\ntowards zero, the distribution shifts towards the midpoint of the unit cell,\nbut the overall shape of the distribution remains the same. Away from this\nlimit, if alternate hoppings are finite, and the on-site interaction is\ndecreased, the distribution also shifts towards the midpoint of the unit cell,\nbut it does this by changing shape, by becoming asymmetric around the maximum,\nas well as by shifting. We also follow the probability distribution of the\npolarization in cycles around the topologically non-trivial point of the model.\nThe distribution moves across to the next unit cell, its shape distorting\nconsiderably in the process. If the radius of the cycle is large, the shift of\nthe distribution is accompanied by large variations in the maximum."
    },
    {
        "anchor": "Spontaneous Breakdown of Translational Symmetry in Quantum Hall Systems:\n  Crystalline Order in High Landau Levels: We report on results of systematic numerical studies of two-dimensional\nelectron gas systems subject to a perpendicular magnetic field, with a high\nLandau level partially filled by electrons. Our results are strongly suggestive\nof a breakdown of translational symmetry and the presence of crystalline order\nin the ground state. This is in sharp contrast with the physics of the lowest\nand first excited Landau levels, and in good qualitative agreement with earlier\nHartree-Fock studies. Experimental implications of our results are discussed.",
        "positive": "The effect of split gate size on the electrostatic potential and 0.7\n  anomaly within one-dimensional quantum wires on a modulation doped\n  GaAs/AlGaAs heterostructure: We study 95 split gates of different size on a single chip using a\nmultiplexing technique. Each split gate defines a one-dimensional channel on a\nmodulation-doped GaAs/AlGaAs heterostructure, through which the conductance is\nquantized. The yield of devices showing good quantization decreases rapidly as\nthe length of the split gates increases. However, for the subset of devices\nshowing good quantization, there is no correlation between the electrostatic\nlength of the one dimensional channel (estimated using a saddle point model),\nand the gate length. The variation in electrostatic length and the\none-dimensional subband spacing for devices of the same gate length exceeds the\nvariation in the average values between devices of different length. There is a\nclear correlation between the curvature of the potential barrier in the\ntransport direction and the strength of the \"0.7 anomaly\": the conductance\nvalue of the 0.7 anomaly reduces as the barrier curvature becomes shallower.\nThese results highlight the key role of the electrostatic environment in\none-dimensional systems. Even in devices with clean conductance plateaus,\nrandom fluctuations in the background potential are crucial in determining the\npotential landscape in the active device area such that nominally identical\ngate structures have different characteristics."
    },
    {
        "anchor": "Nitrogen-vacancy magnetometry of individual Fe-triazole spin crossover\n  nanorods: [Fe(Htrz)2(trz)](BF4) (Fe-triazole) spin crossover molecules show thermal,\nelectrical, and optical switching between high spin (HS) and low spin (LS)\nstates, making them promising candidates for molecular spintronics. The LS and\nHS transitions originate from the electronic configurations of Fe(II), and are\nconsidered to be diamagnetic and paramagnetic respectively. The Fe(II) LS state\nhas six paired electrons in the ground states with no interaction with the\nmagnetic field and a diamagnetic behavior is usually observed. While the bulk\nmagnetic properties of Fe-triazole compounds are widely studied by standard\nmagnetometry techniques their properties at the individual level are missing.\nHere we use nitrogen vacancy (NV) based magnetometry to study the magnetic\nproperties of the Fe-triazole LS state of nanoparticle clusters and individual\nnanorods of size varying from 20 to 1000 nm. Scanning electron microscopy (SEM)\nand Raman spectroscopy are performed to determine the size of the\nnanoparticles/nanorods and to confirm their respective spin state. The magnetic\nfield patterns produced by the nanoparticles/nanorods are imaged by NV magnetic\nmicroscopy as a function of applied magnetic field (up to 350 mT) and\ncorrelated with SEM and Raman. We found that in most of the nanorods the LS\nstate is slightly paramagnetic, possibly originating from the surface oxidation\nand/or the greater Fe(III) presence along the nanorod edges. NV measurements on\nthe Fe-triazole LS state nanoparticle clusters revealed both diamagnetic and\nparamagnetic behavior. Our results highlight the potential of NV quantum\nsensors to study the magnetic properties of spin crossover molecules and\nmolecular magnets.",
        "positive": "The role of the indirect tunneling processes and asymmetry in couplings\n  in orbital Kondo transport through double quantum dots: System of two quantum dots attached to external electrodes is considered\ntheoretically in orbital Kondo regime. In general, the double dot system is\ncoupled via both Coulomb interaction and direct hoping. Moreover, the indirect\nhopping processes between the dots (through the leads) are also taken into\naccount. To investigate system's electronic properties we apply slave-boson\nmean field (SBMF) technique. With help of the SBMF approach the local density\nof states for both dots and the transmission (as well as linear and\ndifferencial conductance) is calculated. We show that Dicke- and Fano-like line\nshape may emerge in transport characteristics of the double dot system.\nMoreover, we observed that these modified Kondo resonances are very susceptible\nto the change of the indirect coupling's strength. We have also shown that the\nKondo temperature become suppressed with increasing asymmetry in the dot-lead\ncouplings when there is no indirect coupling. Moreover, when the indirect\ncoupling is turned on the Kondo temperature becomes suppressed. By allowing a\nrelative sign of the nondiagonal elements of the coupling matrix with left and\nright electrode, we extend our investigations become more generic. Finally, we\nhave also included the level renormalization effects due to indirect tunneling,\nwhich in most papers is not taken into account."
    },
    {
        "anchor": "Finite momentum Cooper pairing in 3D topological insulator Josephson\n  junctions: Unconventional superconductivity arising from the interplay between strong\nspin-orbit coupling and magnetism is an intensive area of research. One form of\nunconventional superconductivity arises when Cooper pairs subjected to a\nmagnetic exchange coupling acquire a finite momentum. Here, we report on a\nsignature of finite momentum Cooper pairing in the 3D topological insulator\nBi2Se3. We apply in-plane and out-of-plane magnetic fields to proximity-coupled\nBi2Se3 and find that the in-plane field creates a spatially oscillating\nsuperconducting order parameter in the junction as evidenced by the emergence\nof an anomalous Fraunhofer pattern. We describe how the anomalous Fraunhofer\npatterns evolve for different device parameters, and we use this to understand\nthe microscopic origin of the oscillating order parameter. The agreement\nbetween the experimental data and simulations shows that the finite momentum\npairing originates from the coexistence of the Zeeman effect and Aharonov-Bohm\nflux.",
        "positive": "Observation of exciton redshift-blueshift crossover in monolayer WS2: We report a rare atom-like interaction between excitons in monolayer WS2,\nmeasured using ultrafast absorption spectroscopy. At increasing excitation\ndensity, the exciton resonance energy exhibits a pronounced redshift followed\nby an anomalous blueshift. Using both material-realistic computation and\nphenomenological modeling, we attribute this observation to plasma effects and\nan attraction-repulsion crossover of the exciton-exciton interaction that\nmimics the Lennard-Jones potential between atoms. Our experiment demonstrates a\nstrong analogy between excitons and atoms with respect to inter-particle\ninteraction, which holds promise to pursue the predicted liquid and crystalline\nphases of excitons in two-dimensional materials."
    },
    {
        "anchor": "Electrostatic environment and Majorana bound states in full-shell\n  topological insulator nanowires: The combination of a superconductor (SC) and a topological insulator (TI)\nnanowire was proposed as a potential candidate for realizing Majorana zero\nmodes (MZMs). In this study, we adopt the Schr\\\"odinger-Poisson formalism to\nincorporate the electrostatic environment inside the nanowire and\nsystematically explore its topological properties. Our calculations reveal that\nthe proximity to the SC induces a band bending effect, leading to a non-uniform\npotential across the TI nanowire. As a consequence, there is an upward shift of\nthe Fermi level within the conduction band. This gives rise to the coexistence\nof surface and bulk states, localized in an accumulation layer adjacent to the\nTI-SC interface. When magnetic flux is applied, these occupied states have\ndifferent flux-penetration areas, suppressing the superconducting gap. However,\nthis impact can be mitigated by increasing the radius of the nanowire. Finally,\nWe demonstrate that MZMs can be achieved across a wide range of parameters\ncentered around one applied flux quantum, $\\phi_0 = h/2e$. Within this regime,\nMZMs can be realized even in the presence of conduction bands, which are not\naffected by the band bending effect. These findings provide valuable insights\ninto the practical realization of MZMs in TI nanowire-based devices, especially\nin the presence of a complicated electrostatic environment.",
        "positive": "Structure-dependent electrical properties of graphene nanoribbon devices\n  with graphene electrodes: Graphene nanoribbons (GNRs) are a novel and intriguing class of materials in\nthe field of nanoelectronics, since their properties, solely defined by their\nwidth and edge type, are controllable with high precision directly from\nsynthesis. Here we study the correlation between the GNR structure and the\ncorresponding device electrical properties. We investigated a series of field\neffect devices consisting of a film of armchair GNRs with different structures\n(namely width and/or length) as the transistor channel, contacted with narrowly\nspaced graphene sheets as the source-drain electrodes. By analyzing several\ntens of junctions for each individual GNR type, we observe that the values of\nthe output current display a width-dependent behavior, indicating electronic\nbandgaps in good agreement with the predicted theoretical values. These results\nprovide insights into the link between the ribbon structure and the device\nproperties, which are fundamental for the development of GNR-based electronics."
    },
    {
        "anchor": "Observation of well-defined Kohn-anomaly in high-quality graphene\n  devices at room temperature: Due to its ultra-thin nature, the study of graphene quantum optoelectronics,\nlike gate-dependent graphene Raman properties, is obscured by interactions with\nsubstrates and surroundings. For instance, the use of doped silicon with a\ncapping thermal oxide layer limited the observation to low temperatures of a\nwell-defined Kohn-anomaly behavior, related to the breakdown of the adiabatic\nBorn-Oppenheimer approximation. Here, we design an optoelectronic device\nconsisting of single-layer graphene electrically contacted with thin graphite\nleads, seated on an atomically flat hexagonal boron nitride (hBN) substrate and\ngated with an ultra-thin gold (Au) layer. We show that this device is optically\ntransparent, has no background optical peaks and photoluminescence from the\ndevice components, and no generation of laser-induced electrostatic doping\n(photodoping). This allows for room-temperature gate-dependent Raman\nspectroscopy effects that have only been observed at cryogenic temperatures so\nfar, above all the Kohn-anomaly phonon energy normalization. The new device\narchitecture by decoupling graphene optoelectronic properties from the\nsubstrate effects, allows for the observation of quantum phenomena at room\ntemperature.",
        "positive": "Spin Cooperated Catalytic Activities in Mn-N4 based Single-atom\n  Nanozyme: Mechanisms and a Brief Charge-spin Model: Although developing artificial enzymes has made great progress, there is\nstill a gap between artificial enzymes and natural enzymes in catalytic\nperformance. Designing and constructing efficient artificial biocatalysts is\nextremely desirable because of their high stability, low cost and easy storage.\nHere, we report a synthesized amino-functionalized graphene quantum dots-based\nmanganese single atom catalyst (SAC) Mn-N4, which exhibits POD-, CAT, SOD-like\nactivities, especially the superior SOD-like activity. Recent studies have\nreported Mn-based SAzymes, however, the multi-enzyme mimicking catalytic\nmechanisms for Mn-N4 are not comprehensive and in-depth enough. Therefore, we\ncombine density functional theory (DFT) calculations and machine learning (ML)\nto validate the performance of the multi-enzyme mimicking activities. The DFT\nsimulations show that Mn-N4 owns a highly effective SOD in the \"one-side\nadsorption\" with a very low energy barrier of 0.077 eV, which can be attributed\nto variation of the preferred spin states of Mn-O2.- system and its \"spin\nflip-collection lock\" in the SOD-like catalytic procedure. Furthermore, spin\nrelated charge distributions on Mn-N4 configurations by machine learning (ML)\nanalysis suggest that the pattern of spin and natural charge/valence electron\ndistribution will exhibit similarity in the structures of multiple intermediate\nsteps of multi-enzyme mimicking activities. This work not only puts forward the\ncatalytic mechanisms of Mn-N4 SAzymes, but also provides essential guidance for\nfuture design of highly performance artificial enzymes."
    },
    {
        "anchor": "Effects of the measurement power on states discrimination and dynamics\n  in a circuit-QED experiment: We explore the effects of driving a cavity at a large photon number in a\ncircuit-QED experiment where the ``matter-like'' part corresponds to an unique\nAndreev level in a superconducting weak link. The three many-body states of the\nweak link, corresponding to the occupation of the Andreev level by 0, 1 or 2\nquasiparticles, lead to different cavity frequency shifts. We show how the\nnon-linearity inherited by the cavity from its coupling to the weak link\naffects the state discrimination and the photon number calibration. Both\neffects require treating the evolution of the driven system beyond the\ndispersive limit. In addition, we observe how transition rates between the\ncircuit states (quantum and parity jumps) are affected by the microwave power,\nand compare the measurements with a theory accounting for the ``dressing'' of\nthe Andreev states by the cavity.",
        "positive": "Direct Observation of Whispering Gallery Mode Polaritons and Their\n  Dispersion in a ZnO Tapered Microcavity: We report direct observation of the strong exciton-photon coupling in ZnO\ntapered whispering gallery (WG) microcavity at room temperature. By scanning\nexcitations along the tapered arm of ZnO tetrapod using micro-photoluminescence\nspectrometer with different polarizations, we observed a transition from the\npure WG optical modes in the weak interaction regime to the excitonic polariton\nin the strong coupling regime. The experimental observations are well described\nby using the plane wave model including excitonic polariton dispersion\nrelation. This provides a direct mapping of the polariton dispersion, and thus\na comprehensive picture for coupling of different excitons with differently\npolarized WG modes."
    },
    {
        "anchor": "Radical-free dynamic nuclear polarization using electronic defects in\n  silicon: Direct dynamic nuclear polarization of 1H nuclei in frozen water and\nwater-ethanol mixtures is demonstrated using silicon nanoparticles as the\npolarizing agent. Electron spins at dangling-bond sites near the silicon\nsurface are identified as the source of the nuclear hyperpolarization. This\nnovel polarization method open new avenues for the fabrication of surface\nengineered nanostructures to create high nuclear-spin polarized solutions\nwithout introducing contaminating radicals, and for the study of molecules\nadsorbed onto surfaces.",
        "positive": "Fano Interference at the Excitation of Coherent Phonons: Relation\n  between the Asymmetry Parameter and the Initial Phase of Coherent\n  Oscillations: The theoretical assertion that the Fano asymmetry parameter and the\nasymptotic initial phase of a harmonic oscillator interacting with a continuum\nare interrelated is experimentally verified. By an example of coherent fully\nsymmetric A1g phonons in bismuth that are excited by ultrashort laser pulses at\nliquid helium temperature, it is demonstrated that, for negative values of the\nasymmetry parameter, the asymptotic phase increases as the modulus of the\nparameter decreases."
    },
    {
        "anchor": "Observation of hedgehog skyrmions in sub-100 nm soft magnetic nanodots: Magnetic skyrmions are nanometric spin textures of outstanding potential for\nspintronic applications due to unique features governed by their non-trivial\ntopology. It is well known that skyrmions of definite chirality are stabilized\nby the Dzyaloshinskii-Moriya exchange interaction (DMI) in bulk\nnon-centrosimmetric materials or ultrathin films with strong spin-orbit\ncoupling in the interface. In this work, we report on the detection of magnetic\nhedgehog-skyrmions at room temperature in confined systems with neither DMI nor\nperpendicular magnetic anisotropy. We show that soft magnetic (permalloy)\nnanodots are able to host non- chiral hedgehog skyrmions that can be further\nstabilized by the magnetic field arising from the Magnetic Force Microscopy\nprobe. Analytical calculations and micromagnetic simulations confirmed the\nexistence of metastable N\\'eel skyrmions in permalloy nanodots even without\nexternal stimuli in a certain size range. Our work implies the existence of a\nnew degree of freedom to create and manipulate skyrmions in soft nanodots. The\nstabilization of skyrmions in soft magnetic materials opens a possibility to\nstudy the skymion magnetization dynamics otherwise limited due to the large\ndamping constant coming from the high spin-orbit coupling in materials with\nhigh magnetic anisotropy.",
        "positive": "Photon properties of single graphene nanoribbon microcavity laser: In this work, I propose a scheme about a single graphene nanoribbon (GNR)\nemitter in a microcavity, and focus on a fully-quantum-mechanical treatment\nmodel with the excitonic interaction included to investigate the photon\nproperties and lasing action. When the single armchair-edged GNRs (AGNRs)\nmicrocavity system is pumped, the exciton-photon coupling provides more photons\nand enhances the photon emission process, making it essentially a lasing\nobject. The theoretical results demonstrated that single AGNR in a\nsemiconductor microcavity system maybe serve as a nanolaser with ultralow\nlasing threshold."
    },
    {
        "anchor": "Magnetooptical determination of a topological index: When a Dirac fermion system acquires an energy-gap, it is said to have either\ntrivial (positive energy-gap) or non-trivial (negative energy-gap) topology,\ndepending on the parity ordering of its conduction and valence bands. The\nnon-trivial regime is identified by the presence of topological surface or\nedge-state dispersing in the energy gap of the bulk and is attributed a\nnon-zero topological index. In this work, we show that such topological indices\ncan be determined experimentally via an accurate measurement of the effective\nvelocity of bulk massive Dirac fermions. We demonstrate this analytically\nstarting from the Bernevig-Hughes-Zhang Hamiltonian (BHZ) to show how the\ntopological index depends on this velocity. We then experimentally extract the\ntopological index in Pb1-xSnxSe and Pb1-xSnxTe using infrared magnetooptical\nLandau level spectroscopy. This approach is argued to be universal to all\nmaterial classes that can be described by a BHZ-like model and that host a\ntopological phase transition.",
        "positive": "Tunable mechanical coupling between driven microelectromechanical\n  resonators: We present a microelectromechanical system, in which a silicon beam is\nattached to a comb-drive actuator, that is used to tune the tension in the\nsilicon beam, and thus its resonance frequency. By measuring the resonance\nfrequencies of the system, we show that the comb-drive actuator and the silicon\nbeam behave as two strongly coupled resonators. Interestingly, the effective\ncoupling rate (~ 1.5 MHz) is tunable with the comb-drive actuator (+10%) as\nwell as with a side-gate (-10%) placed close to the silicon beam. In contrast,\nthe effective spring constant of the system is insensitive to either of them\nand changes only by $\\pm$ 0.5%. Finally, we show that the comb-drive actuator\ncan be used to switch between different coupling rates with a frequency of at\nleast 10 kHz."
    },
    {
        "anchor": "Comment on \"Aharonov-Casher and Scalar Aharonov-Bohm Topological\n  Effects\": In this Comment we point out (i) that the Hamiltonian, Eq. (17) in the\nLetter(Phys. Rev. Lett. 108, 070405 (2012)), is not a relativistic Hamiltonian,\n(ii) then that the conditions in the Letter are irrelevant for a topological AC\nand SAB effects, and (iii) conclusively that the non-relativistic Hamiltonian\nemployed by Peshkin and Lipkin (Phys. Rev. Lett. 74, 2847 (1995)) has the same\n$U(1)_{mm}$ gauge structure for a fixed spin and then is not wrong, but their\nincorrect interpretation of the spin autocorrelations led to the incorrect\nconclusion.",
        "positive": "Killing Auger recombination in nanostructures by carrier spin\n  polarization: In semiconductor nanostructures nonradiative Auger recombination is enhanced\nby the presence of boundaries which relax the momentum conservation and thereby\nremoves the threshold reduction for these processes. We propose a method to\nstrongly reduce the Auger recombination rate by injecting spin-polarized\ncarriers. Our method is illustrated on the example of a quantum well in which\nthe spin-orbit coupling of conduction band is negligible as compared to valence\nband and thus holes can be considered as spin-unpolarized. The suppression\nfactor of the Auger recombination is determined by the two-dimensional\ncharacter of the system, given by the ratio of the Fermi energy of electrons\nand the separation of the electron levels quantized in the growth direction.\nOur predictions can be tested experimentally and we discuss their implications\nfor semiconductor lasers relying on injection of spin-polarized electrons."
    },
    {
        "anchor": "Anisotropic and strong negative magneto-resistance in the\n  three-dimensional topological insulator Bi2Se3: We report on high-field angle-dependent magneto-transport measurements on\nepitaxial thin films of Bi2Se3, a three-dimensional topological insulator. At\nlow temperature, we observe quantum oscillations that demonstrate the\nsimultaneous presence of bulk and surface carriers. The magneto- resistance of\nBi2Se3 is found to be highly anisotropic. In the presence of a parallel\nelectric and magnetic field, we observe a strong negative longitudinal\nmagneto-resistance that has been consid- ered as a smoking-gun for the presence\nof chiral fermions in a certain class of semi-metals due to the so-called axial\nanomaly. Its observation in a three-dimensional topological insulator implies\nthat the axial anomaly may be in fact a far more generic phenomenon than\noriginally thought.",
        "positive": "Symmetry-dependent ultrafast manipulation of nanoscale magnetic domains: Symmetry is a powerful concept in physics, but its applicability to\nfar-from-equilibrium states is still being understood. Recent attention has\nfocused on how far-from-equilibrium states lead to spontaneous symmetry\nbreaking. Conversely, ultrafast optical pumping can be used to drastically\nchange the energy landscape and quench the magnetic order parameter in magnetic\nsystems. Here, we find a distinct symmetry-dependent ultrafast behaviour by use\nof ultrafast x-ray scattering from magnetic patterns with varying degrees of\nisotropic and anisotropic symmetry. After pumping with an optical laser, the\nscattered intensity reveals a radial shift exclusive to the isotropic component\nand exhibits a faster recovery time from quenching for the anisotropic\ncomponent. These features arise even when both symmetry components are\nconcurrently measured, suggesting a correspondence between the excitation and\nthe magnetic order symmetry. Our results underline the importance of symmetry\nas a critical variable to manipulate the magnetic order in the ultrafast\nregime."
    },
    {
        "anchor": "Unintentional high density p-type modulation doping of a GaAs/AlAs\n  core-multi-shell nanowire: Achieving significant doping in GaAs/AlAs core/shell nanowires (NWs) is of\nconsiderable technological importance but remains a challenge due to the\namphoteric behavior of the dopant atoms. Here we show that placing a narrow\nGaAs quantum well in the AlAs shell effectively getters residual carbon\nacceptors leading to an \\emph{unintentional} p-type doping. Magneto-optical\nstudies of such a GaAs/AlAs core multi-shell NW reveal quantum confined\nemission. Theoretical calculations of NW electronic structure confirm quantum\nconfinement of carriers at the core/shell interface due to the presence of\nionized carbon acceptors in the 1~nm GaAs layer in the shell.\nMicro-photoluminescence in high magnetic field shows a clear signature of\navoided crossings of the $n=0$ Landau level emission line with the $n=2$ Landau\nlevel TO phonon replica. The coupling is caused by the resonant hole-phonon\ninteraction, which points to a large 2D hole density in the structure.",
        "positive": "The Nature of the magnetism-promoting hole state in the prototype\n  magnetic semiconductor GaAs: Mn: Recent experiments [1] suggest that the ferromagnetism (FM) in GaAs: Mn is\ndetermined by the impurity band rather than holes in the valence band. We\ndiscuss here the physical mechanism of FM mediated by the carriers in impurity\nband, where the Mn d-level play a crucial role. The theory is based on the\nfirst principle approach."
    },
    {
        "anchor": "Environmental Effects on the Terahertz Surface Plasmons in Epitaxial\n  Graphene: In this paper, we predict the existence of low-frequency nonlocal plasmon\nexcitations at the vacuum-surface interface of a superlattice of $N$ graphene\nlayers interacting with a thick conducting substrate. This is different from\ngraphite which allows inter-layer hopping. A dispersion function is derived\nwhich incorporates the polarization function of the graphene monolayers (MLGs)\nand the dispersion function of a semi-infinite electron liquid at whose surface\nthe electrons scatter specularly. We find that this surface plasmon-polariton\nis not damped by the particle-hole excitations (PHE's) or the bulk modes and\nseparates below the continuum mini-band of bulk plasmon modes. For a conducting\nsubstrate with surface plasmon frequency $\\omega_s=\\omega_p/\\sqrt{2}$, the\nsurface plasmon frequency of the hybrid structure always lies below $\\omega_s$.\nThe intensity of this mode depends on the distance of the graphene layers from\nthe surface of the conductor, the energy band gap between the valence and\nconduction bands of MLG and, most importantly, on the number of two-dimensional\n(2D) layers. Furthermore, the hybrid structure has no surface plasmon for a\nsufficiently large number ($N\\stackrel{>}{\\sim} 7$) of layers. The existence of\ntwo plasmons with different dispersion relations indicates that quasiparticles\nwith different group velocity may coexist for various ranges of wavelength\nwhich is determined by the number of layers in the superlattice.",
        "positive": "Anomalous temperature dependence of current induced torques in CoFeB|MgO\n  heterostructures with Ta based underlayers: We have studied the underlayer thickness and temperature dependences of the\ncurrent induced effective field in CoFeB|MgO heterostructures with Ta based\nunderlayers. The underlayer thickness at which the effective field saturates is\nfound to be different between the two orthogonal components of the effective\nfield, i.e. the damping-like term tends to saturate at smaller underlayer\nthickness than the field-like term. For large underlayer thickness films in\nwhich the effective field saturates, we find that the temperature significantly\ninfluences the size of the effective field. A striking difference is found in\nthe temperature dependence of the two components: the damping-like term\ndecreases whereas the field-like term increases with increasing temperature.\nUsing a simple spin diffusion-spin transfer model, we find that all of these\nresults can be accounted for provided the real and imaginary parts of an\neffective spin mixing conductance are negative. These results imply that either\nspin transport in this system is different from conventional metallic\ninterfaces or effects other spin diffusion into the magnetic layer need to be\ntaken account in order to model the system accurately."
    },
    {
        "anchor": "Revealing large-scale homogeneity and trace impurity sensitivity of GaAs\n  nanoscale membranes: III-V nanostructures have the potential to revolutionize optoelectronics and\nenergy harvesting. For this to become a reality, critical issues such as\nreproducibility and sensitivity to defects should be resolved. By discussing\nthe optical properties of MBE grown GaAs nanomembranes we highlight several\nfeatures that bring them closer to large scale applications. Uncapped membranes\nexhibit a very high optical quality, expressed by extremely narrow neutral\nexciton emission, allowing the resolution of the more complex excitonic\nstructure for the first time. Capping of the membranes with an AlGaAs shell\nresults in a strong increase of emission intensity but also to a shift and\nbroadening of the exciton peak. This is attributed to the existence of\nimpurities in the shell, beyond MBE-grade quality, showing the high sensitivity\nof these structures to the presence of impurities. Finally, emission properties\nare identical at the sub-micron and sub-millimeter scale, demonstrating the\npotential of these structures for large scale applications.",
        "positive": "Topological Phase Transition of A Non-Hermitian Crosslinked Chain: Non-Hermiticity enriches the contents of topological classification of matter\nincluding exceptional points, bulk-edge correspondence and skin effect. Gain\nand loss can be described by imaginary diagonal elements in Hamiltonians and\nthe topological phase transition for a crosslinked chain in the presence of\nsuch non-Hermiticity is investigated in this work. We obtain the phase diagram\nin term of a winding number analytically. The boundaries of the phases coincide\nwith the surfaces of exceptional points in the parameter space. The\ntopologically original edge states locating mainly at the joints between\ndomains of different phases hold on even for the long chain. The non-Hermitian\ntopological feature can also be reflected by vortex structures in the vector\nfields of complex eigenenergies and expected values of Pauli matrices or the\ntrajectories of these quantities. This model can be implemented in coupled\nwaveguides or photonic crystals. And the edge states are immune to various\nkinds of disorders until the topological phase transition occurs. This work\nbenefits our insight into the influence of gain and loss on the topological\nphase of matter."
    },
    {
        "anchor": "Conductance fluctuations in metallic nanogaps made by electromigration: We report on low temperature conductance measurements of gold nanogaps\nfabricated by controlled electromigration. Fluctuations of the conductance due\nto quantum interferences and depending both on bias voltage and magnetic field\nare observed. By analyzing the voltage and magnetoconductance correlation\nfunctions we determine the type of electron trajectories generating the\nobserved quantum interferences and the effective characteristic time of phase\ncoherence in our device.",
        "positive": "Low-energy trions in graphene quantum dots: We investigate, within the envelope function approximation, the low-energy\nstates of trions in graphene quantum dots. The presence of valley pseudospin in\ngraphene as an electron degree of freedom apart from spin adds convolution to\nthe interplay between exchange symmetry and the electron-electron interaction\nin the trion, leading to new states of trions as well as a low energy trion\nspectrum different from those in semiconductors. Due to the involvement of\nvalley pseudospin, it is found that the low-energy spectrum is nearly\ndegenerate and consists of states all characterized by having an antisymmetric\n(pseudospin) (spin) component in the wave function, with the spin (pseudospin)\npart being either singlet (triplet) or triplet (singlet), as opposed to the\nspectrum in a semiconductor whose ground state is known to be nondegenerate and\nalways a spin singlet in the case of X- trions. We investigate trions in the\nvarious regimes determined by the competition between quantum confinement and\nelectron-electron interaction, both analytically and numerically. The numerical\nwork is performed within a variational method accounting for electron mass\ndiscontinuity across the QD edge. The result for electron-hole correlation in\nthe trion is presented. Effects of varying quantum dot size and confinement\npotential strength on the trion binding energy are discussed."
    },
    {
        "anchor": "Multifractal wave functions of charge carriers in graphene with folded\n  deformations, ripples or uniaxial flexural modes: analogies to the quantum\n  Hall effect under random pseudomagnetic fields: The electronic behavior in graphene under arbitrary uniaxial deformations,\nsuch as foldings or flexural fields is studied by including in the Dirac\nequation pseudoelectromagnetic fields. General foldings are thus studied by\nshowing that uniaxial deformations can be considered pseudomagnetic fields in\nthe Coulomb gauge norm. This allows to give an expression for the Fermi (zero)\nenergy modes wavefunctions. For random deformations, contact is made with\nprevious works on the quantum Hall effect under random magnetic fields, showing\nthat the density of states has a power law behavior and that the zero energy\nmodes wavefunctions are multifractal. This hints at an unusual electron\nvelocity distribution. Also, it is shown that a strong Aharonov-Bohm\npseudo-effect is produced. For more general non-uniaxial general flexural\nstrain, it is not possible to use the Coulomb gauge. The results presented here\nhelps to tailor-made graphene uniaxial deformations to achieve specific\nwavefunctions.",
        "positive": "Probing the validity of the diffuse mismatch model for phonons using\n  atomistic simulations: Due to it's simplicity the diffuse mismatch model (DMM) remains a popular\ndescription of phonon transmission across solid-solid boundaries. However, it\nremains unclear in which situations the DMM should be expected to be a valid\nmodel of the underlying physics. Here, its validity is investigated\nmode-by-mode using a 3-dimensional extension of the frequency domain, perfectly\nmatched layer (FD-PML) method, to study the interface between face-centered\ncubic solids with interdiffused atoms. While submonolayer levels of\ninterdiffusion are found to increase the number of available modes for\ntransmission, consistent qualitatively with the DMM, we do not find\nquantitative or qualitative convergence toward the DMM at higher levels of\ninterdiffusion. In particular, contrary to the fundamental assumption of the\nDMM, modes are not found to lose memory of their initial polarization and\nwavevector. The transmission coefficients of randomly interdiffused and\nsmoothly-graded interfaces are also compared. While smoothly graded interfaces\nshow strong anti-reflection properties, selection rules still prohibit\ntransmission of many modes, whereas interdiffused interfaces are not subject to\nsuch rules and achieve similar thermal interface conductance by transmitting\nwith lower probability but using a wider range of modes."
    },
    {
        "anchor": "Optical exciton Aharonov-Bohm effect, persistent current, and\n  magnetization in semiconductor nanorings of type I and II: The optical exciton Aharonov-Bohm effect, i. e. an oscillatory component in\nthe energy of optically active (bright) states, is investigated in nanorings.\nIt is shown that a small effective electron mass, strong confinement of the\nelectron, and high barrier for the hole, achieved e. g. by an InAs nanoring\nembedded in an AlGaSb quantum well, are favorable for observing the optical\nexciton Aharonov-Bohm effect. The second derivative of the exciton energy with\nrespect to the magnetic field is utilized to extract Aharonov-Bohm oscillations\neven for the lowest bright state unambiguously. A connection between the\ntheories for infinitesimal narrow and finite width rings is established.\nFurthermore, the magnetization is compared to the persistent current, which\noscillates periodically with the magnetic field and confirms thus the\nnon-trivial (connected) topology of the wave function in the nanoring.",
        "positive": "Revealing dark exciton signatures in polariton spectra of 2D materials: Dark excitons in transition metal dichalcogenides (TMD) have been so far\nneglected in the context of polariton physics due to their lack of oscillator\nstrength. However, in tungsten-based TMDs, dark excitons are known to be the\nenergetically lowest states and could thus provide important scattering\npartners for polaritons. In this joint theory-experiment work, we investigate\nthe impact of the full exciton energy landscape on polariton absorption and\nreflectance. By changing the cavity detuning, we vary the polariton energy\nrelative to the unaffected dark excitons in such a way that we open or close\nspecific phonon-driven scattering channels. We demonstrate both in theory and\nexperiment that this controlled switching of scattering channels manifests in\ncharacteristic sharp changes in optical spectra of polaritons. These spectral\nfeatures can be exploited to extract the position of dark excitons. Our work\nsuggests new possibilities for exploiting polaritons for fingerprinting\nnanomaterials via their unique exciton landscape."
    },
    {
        "anchor": "Robust and fragile Majorana bound states in proximitized topological\n  insulator nanoribbons: Topological insulator (TI) nanoribbons with proximity-induced\nsuperconductivity are a promising platform for Majorana bound states (MBSs). In\nthis work, we consider a detailed modeling approach for a TI nanoribbon in\ncontact with a superconductor via its top surface, which induces a\nsuperconducting gap in its surface-state spectrum. The system displays a rich\nphase diagram with different numbers of end-localized MBSs as a function of\nchemical potential and magnetic flux piercing the cross section of the ribbon.\nThese MBSs can be robust or fragile upon consideration of electrostatic\ndisorder. We simulate a tunneling spectroscopy setup to probe the different\ntopological phases of top-proximitized TI nanoribbons. Our simulation results\nindicate that a top-proximitized TI nanoribbon is ideally suited for realizing\nfully gapped topological superconductivity, in particular when the Fermi level\nis pinned near the Dirac point. In this regime, the setup yields a single pair\nof MBSs, well separated at opposite ends of the proximitized ribbon, which\ngives rise to a robust quantized zero-bias conductance peak.",
        "positive": "On the plasmon dispersion in biased graphene bilayer: Plasma oscillations in doped graphene bilayer at zero temperature has been\ninvestigated. Bias voltage effect on the dispersion curve for plasmon in\nbigraphene has been studied in random phase approximation. The possibility of\ncontrolling of curvature of dispersion curve for plasmon by changing of bias\nvoltage has been shown. The dependence of this curvature on the bias voltage\nhas been predicted to have the nonmonotonous character. Namely the existence of\nbreaking point for such dependence has been found out. The bias voltage\ncorresponding to the breaking point is shown to increase with free carriers\nconcentration as square root of concentration."
    },
    {
        "anchor": "Skyrmion and helical states in thin layers of magnets and liquid\n  crystals: Novel types of barrel-shaped chiral skyrmions can exist as isolated\ntopological defects or as bound states in magnetic nanolayers with intrinsic\nand surface/interface induced chirality. The equilibrium parameters of chiral\nmodulations calculated as functions of applied fields, layer thicknesses, and\nvalues of surface and volume uniaxial anisotropies allow to find optimal\nparameters for skyrmionic states in magnetic nanolayers. Our findings also show\nthat in cholesteric cells with homeotropic anchoring smooth skyrmionic textures\ncan be induced as an intriguing alternative to common disclination penetrated\npatterns.",
        "positive": "Quantum frequency locking and down-conversion in a driven cavity-qubit\n  system: We study a periodically driven qubit coupled to a quantized cavity mode.\nDespite its apparent simplicity, this system supports a rich variety of exotic\nphenomena, such as topological frequency conversion as recently discovered in\n[Martin et al, PRX 7, 041008 (2017)]. Here we report on a qualitatively\ndifferent phenomenon that occurs in this platform, where the cavity mode's\noscillations lock their frequency to a rational fraction $r/q$ of the driving\nfrequency $\\Omega$. This phenomenon, which we term quantum frequency locking,\nis characterized by the emergence of $q$-tuplets of stationary (Floquet) states\nwhose quasienergies are separated by $\\Omega/q$, up to exponentially small\ncorrections. The Wigner functions of these states are nearly identical, and\nexhibit highly-regular and symmetric structure in phase space. Similarly to\nFloquet time crystals, these states underlie discrete time-translation symmetry\nbreaking in the model. We develop a semiclassical approach for analyzing and\npredicting quantum frequency locking in the model, and use it to identify the\nconditions under which it occurs."
    },
    {
        "anchor": "Time-periodic corner states from Floquet higher-order topology: The recent discoveries of higher-order topological insulators (HOTIs) have\nshifted the paradigm of topological materials, which was previously limited to\ntopological states at boundaries of materials, to those at boundaries of\nboundaries, such as corners . So far, all HOTI realisations have assumed static\nequilibrium described by time-invariant Hamiltonians, without considering\ntime-variant or nonequilibrium properties. On the other hand, there is growing\ninterest in nonequilibrium systems in which time-periodic driving, known as\nFloquet engineering, can induce unconventional phenomena including Floquet\ntopological phases and time crystals. Recent theories have attemped to combine\nFloquet engineering and HOTIs, but there has thus far been no experimental\nrealisation. Here we report on the experimental demonstration of a\ntwo-dimensional (2D) Floquet HOTI in a three-dimensional (3D) acoustic lattice,\nwith modulation along z axis serving as an effective time-dependent drive.\nDirect acoustic measurements reveal Floquet corner states that have\ntime-periodic evolution, whose period can be even longer than the underlying\ndrive, a feature previously predicted for time crystals. The Floquet corner\nstates can exist alongside chiral edge states under topological protection,\nunlike previous static HOTIs. These results demonstrate the unique space-time\ndynamic features of Floquet higher-order topology.",
        "positive": "Spin and charge transport through helical Aharonov-Bohm interferometer\n  with strong magnetic impurity: We discuss transport through an interferometer formed by helical edge states\nof the quantum spin Hall insulator. Focusing on effects induced by a strong\nmagnetic impurity placed in one of the arms of interferometer, we consider the\nexperimentally relevant case of relatively high temperature as compared to the\nlevel spacing. We obtain the conductance and the spin polarization in the\nclosed form for arbitrary tunneling amplitude of the contacts and arbitrary\nstrength of the magnetic impurity. We demonstrate the existence of quantum\neffects which do not show up in previously studied case of weak magnetic\ndisorder. We find optimal conditions for spin filtering and demonstrate that\nthe spin polarization of outgoing electrons can reach 100%."
    },
    {
        "anchor": "Intrinsic Spin Hall Effect: Topological Transitions in Two-Dimensional\n  Systems: The spin-Hall conductivity in spatially-homogeneous two-dimensional electron\nsystems described by the spin-orbit Hamiltonian \\hbar \\Omega_p \\sigma is\npresented as a sum of the universal part Me/8 \\pi \\hbar determined by the Berry\nphase \\Phi=M \\pi (M is an odd integer, the winding number of the vector\n\\Omega_p) and a non-universal part which vanishes under certain conditions\ndetermined by the analytical properties of \\Omega_p. The analysis reveals a\nrich and complicated behavior of the spin-Hall conductivity which is relevant\nto both electron and hole states in quantum wells and can be detected in\nexperiments.",
        "positive": "Geometric nature of the environment-induced Berry phase and geometric\n  dephasing: We investigate the geometric phase or Berry phase (BP) acquired by a\nspin-half which is both subject to a slowly varying magnetic field and\nweakly-coupled to a dissipative environment (either quantum or classical). We\nstudy how this phase is modified by the environment and find that the\nmodification is of a geometric nature. While the original BP (for an isolated\nsystem) is the flux of a monopole-field through the loop traversed by the\nmagnetic field, the environment-induced modification of the BP is the flux of a\nquadrupole-like field. We find that the environment-induced phase is complex,\nand its imaginary part is a geometric contribution to dephasing. Its sign\ndepends on the direction of the loop. Unlike the BP, this geometric dephasing\nis gauge invariant for open paths of the magnetic field."
    },
    {
        "anchor": "Current rectification in molecular junctions produced by local potential\n  fields: The transport properties of a octane-dithiol (ODT) molecule coupled to\nAu(001) leads are analyzed using density functional theory and non-equilibrium\nGreen functions. It is shown that a symmetric molecule can turn into a diode\nunder influence of a local electric field created by an external charged probe.\nThe origin of the asymmetry of the current--voltage ($I-V$) dependence is\ntraced back to the appearance of a probe induced quasi--local state in the\npseudogap of the ODT molecule. The induced state affects electron transport,\nprovided it is close to the Fermi level of the leads. An asymmetric placement\nof the charged probe along the alkane chain makes the induced quasi--local\nstate in the energy gap very sensitive to the bias voltage and results in\nrectification of the current. The results based on DFT are supported by\nindependent calculations using a simple one--particle model Hamiltonian.",
        "positive": "Non-reciprocal quantum Hall devices with driven edge magnetoplasmons in\n  2-dimensional materials: We develop a theory that describes the response of non-reciprocal devices\nemploying 2-dimensional materials in the quantum Hall regime capacitively\ncoupled to external electrodes. As the conduction in these devices is\nunderstood to be associated to the edge magnetoplasmons (EMPs), we first\ninvestigate the EMP problem by using the linear response theory in the random\nphase approximation. Our model can incorporate several cases, that were often\ntreated on different grounds in literature. In particular, we analyze plasmonic\nexcitations supported by smooth and sharp confining potential in 2-dimensional\nelectron gas, and in monolayer graphene, and we point out the similarities and\ndifferences in these materials. We also account for a general time-dependent\nexternal drive applied to the system. Finally, we describe the behavior of a\nnon-reciprocal quantum Hall device: the response contains additional resonant\nfeatures, which were not foreseen from previous models."
    },
    {
        "anchor": "Longitudinal and transverse electron paramagnetic resonance in a\n  scanning tunneling microscope: Electron paramagnetic resonance (EPR) spectroscopy is widely employed to\ncharacterize paramagnetic complexes. Recently, EPR combined with scanning\ntunneling microscopy (STM) achieved single-spin sensitivity with sub-angstrom\nspatial resolution. The excitation mechanism of EPR in STM, however, is broadly\ndebated, raising concerns about widespread application of this technique. Here,\nwe present an extensive experimental study and modelling of EPR-STM of Fe and\nhydrogenated Ti atoms on an MgO surface. Our results support a piezoelectric\ncoupling mechanism, in which the EPR species oscillate adiabatically in the\ninhomogeneous magnetic field of the STM tip. An analysis based on Bloch\nequations combined with atomic-multiplet calculations identifies different EPR\ndriving forces. Specifically, transverse magnetic-field gradients drive the\nspin-1/2 hydrogenated Ti, whereas longitudinal magnetic-field gradients drive\nthe spin-2 Fe. Additionally, our results highlight the potential of\npiezoelectric coupling to induce electric dipole moments, thereby broadening\nthe scope of EPR-STM to nonpolar species and nonlinear excitation schemes.",
        "positive": "Evolution of clusters in energetic heavy ion bombarded amorphous\n  graphite-II: formation and fragmentation phenomena: A study has been conducted into the mechanisms of evolution of clusters and\ntheir subsequent fragmentation under energetic heavy ion bombardment of\namorphous graphite. The evolving clusters and their subsequent fragmentation\nunder continuing ion bombardment are revealed by detecting various clusters in\nthe energy spectra of the Direct Recoils emitted as a result of collisions\nbetween ions and surface constituents. The successive Direct Recoil spectra\nreveal that the energetics of Carbon Carbon bond formation as well as any\nsubsequent fragmentation can be related to the processes of energy dissipation\nin a cylindrical volume of a few Angstrom surrounding the ion path. The\ndependence of cluster with m carbon atoms formation or its subsequent\nfragmentation into cluster with m-2 carbon atoms and diatomic carbon C2 is seen\nto be a function of the ionic stopping powers in this cylindrical volume."
    },
    {
        "anchor": "Anomalous external-magnetic-field dependence of dephasing in a spin bath: We theoretically investigate the dephasing of a central spin-1 model. An\ninteresting mechanism of spin decoherence is found with this model, namely {\\em\nhyperfine mediated spectral diffusion}. This mechanism contains both the\nfeatures of dipolar interactions induced spectral diffusion and hyperfine\nmediated interactions. We also find an anomalous magnetic field dependence of\ndecoherence, which is caused by the competition between crystal field splitting\nand Zeeman splitting of the central spin. As the external magnetic field\nincreases, in the V type level structure regime, the decoherence rate becomes\nmuch stronger; while in the cascade type level structure regime, just like\nlocalized electron spin in quantum dots, the decoherence rate becomes much\nweaker.",
        "positive": "Spin-induced charge correlations in transport through interacting\n  quantum dots with ferromagnetic leads: We study the full counting statistics of electronic transport through a\nsingle-level quantum dot weakly coupled to two leads, with either one or both\nof them being ferromagnetic. The interplay of Coulomb interaction and finite\nspin polarization implies spin-correlation induced charge correlations that\ngive rise to super-Poissonian transport behavior and positive cross\ncorrelations of the currents of the two spin species. In the case of two\nferromagnetic leads, we analyze the nontrivial dependence of the cumulants on\nthe angle between the polarization directions of the leads. We find diverging\nsecond and higher cumulants for spin polarizations approaching unity."
    },
    {
        "anchor": "Parametric Hierarchical Matrix Approach for the Wideband Optical\n  Response of Large-Scale Molecular Aggregates: Fast and efficient calculations of optical responses using electromagnetic\nmodels require computational acceleration and compression techniques. A\nhierarchical matrix approach is adopted for this purpose. In order to model\nlarge-scale molecular structures these methods should be applied over wide\nfrequency spectra. Here we introduce a novel parametric hierarchical matrix\nmethod that allows one for a rapid construction of a wideband system\nrepresentation and enables an efficient wideband solution. We apply the\ndeveloped method to the modeling of the optical response of bacteriochorophyll\ntubular aggregates as found in green photosynthetic bacteria. We show that the\nparametric method can provide one with the frequency and time-domain solutions\nfor structures of the size of 100, 000 molecules, which is comparable to the\nsize of the whole antenna complex in a bacterium. The absorption spectrum is\ncalculated and the significance of electrodynamic retardation effects for\nrelatively large structures, i.e. with respect to the wavelength of light, is\nbriefly studied.",
        "positive": "Current-induced torques and interfacial spin-orbit coupling: In bilayer systems consisting of an ultrathin ferromagnetic layer adjacent to\na metal with strong spin-orbit coupling, an applied in-plane current induces\ntorques on the magnetization. The torques that arise from spin-orbit coupling\nare of particular interest. Here, we calculate the current-induced torque in a\nPt-Co bilayer to help determine the underlying mechanism using first principles\nmethods. We focus exclusively on the analogue to the Rashba torque, and do not\nconsider the spin Hall effect. The details of the torque depend strongly on the\nlayer thicknesses and the interface structure, providing an explanation for the\nwide variation in results found by different groups. The torque depends on the\nmagnetization direction in a way similar to that found for a simple Rashba\nmodel. Artificially turning off the exchange spin splitting and separately the\nspin-orbit coupling potential in the Pt shows that the primary source of the\n\"field-like\" torque is a proximate spin-orbit effect on the Co layer induced by\nthe strong spin-orbit coupling in the Pt."
    },
    {
        "anchor": "Hybridization-induced interface states in a topological\n  insulator-magnetic metal heterostructure: Recent experiments demonstrating large spin-transfer torques in topological\ninsulator (TI)-ferromagnetic metal (FM) bilayers have generated a great deal of\nexcitement due to their potential applications in spintronics. The source of\nthe observed spin-transfer torque, however, remains unclear. This is because\nthe large charge transfer from the FM to TI layer would prevent the Dirac cone\nat the interface from being anywhere near the Fermi level to contribute to the\nobserved spin-transfer torque. Moreover, there is yet little understanding of\nthe impact on the Dirac cone at the interface from the metallic bands\noverlapping in energy and momentum, where strong hybridization could take\nplace. Here, we build a simple microscopic model and perform\nfirst-principles-based simulations for such a TI-FM heterostructure,\nconsidering the strong hybridization and charge transfer effects. We find that\nthe original Dirac cone is destroyed by the hybridization as expected. Instead,\nwe find a new interface state which we dub 'descendent state' to form near the\nFermi level due to the strong hybridization with the FM states at the same\nmomentum. Such a `descendent state' carries a sizable weight of the original\nDirac interface state, and thus inherits the localization at the interface and\nthe same Rashba-type spin-momentum locking. We propose that the `descendent\nstate' may be an important source of the experimentally observed large\nspin-transfer torque in the TI-FM heterostructure.",
        "positive": "Transport properties of non-equilibrium systems under the application of\n  light: Photo-induced quantum Hall insulators without Landau levels: In this paper, we study transport properties of non-equilibrium systems under\nthe application of light in many-terminal measurements, using the Floquet\npicture. We propose and demonstrate that the quantum transport properties can\nbe controlled in materials such as graphene and topological insulators, via the\napplication of light. Remarkably, under the application of off-resonant light,\ntopological transport properties can be induced; these systems exhibits quantum\nHall effects in the absence of a magnetic field with a near quantization of the\nHall conductance, realizing so-called quantum Hall systems without Landau\nlevels first proposed by Haldane."
    },
    {
        "anchor": "Spin-Orbit Coupling of Conduction Electrons in Magnetization Switching: Strong magnetic field pulses associated with a relativistic electron bunch\ncan imprint switching patterns in magnetic thin films that have uniaxial\nin-plane anisotropy. In experiments with Fe and FeCo alloy films the pattern\nshape reveals an additional torque acting on magnetization during the short (in\nthe 100fs time scale) magnetic field pulse. The magnitude of the torque is as\nhigh as 15% of the torque from the magnetic field. The torque symmetry is that\nof a uniaxial anisotropy along the direction of the eddy current screening the\nmagnetic field. Spin-orbit interaction acting on the conduction electrons can\nproduce such a torque with the required symmetry and magnitude. The same\ninteraction causes the anomalous Hall current to be spin-polarized, exerting a\nback reaction on magnetization direction. Such a mechanism may be at work in\nall-optical laser switching of magnetic materials.",
        "positive": "Spatial and Spectral Multifractality of the Local Density of States at\n  the Mobility Edge: We performed numerical calculations of the local density of states (LDOS) at\ndisorder induced localization-delocalization transitions. The LDOS defines a\nspatial measure for fixed energy and a spectral measure for fixed position. At\nthe mobility edge both measures are multifractal and their generalized\ndimensions $D(q)$ and $\\tilde{D}(q)$ are found to be proportional:\n$D(q)=d\\tilde{D}(q)$, where $d$ is the dimension of the system. This\nobservation is consistent with the identification of the frequency-dependent\nlength scale $L_\\omega \\propto \\omega^{-1/d}$ as an effective system size. The\ncalculations are performed for two- and three-dimensional dynamical network\nmodels with local time evolution operators. The energy dependence of the LDOS\nis obtained from the time evolution of the local wavefunction amplitude of a\nwave packet, providing a numerically efficient way to obtain information about\nthe multifractal exponents of the system."
    },
    {
        "anchor": "Spin injection and perpendicular spin transport in graphite\n  nanostructures: Organic and carbon-based materials are attractive for spintronics because\ntheir small spin-orbit coupling and low hyperfine interaction is expected to\ngive rise to large spin-relaxation times. However, the corresponding\nspin-relaxation length is not necessarily large when transport is via weakly\ninteracting molecular orbitals. Here we use graphite as a model system and\nstudy spin transport in the direction perpendicular to the weakly bonded\ngraphene sheets. We achieve injection of highly (75%) spin-polarized electrons\ninto graphite nanostructures of 300-500 nm across and up to 17 nm thick, and\nobserve transport without any measurable loss of spin information. Direct\nvisualization of local spin transport in graphite-based spin-valve sandwiches\nalso shows spatially uniform and near-unity transmission for electrons at 1.8\neV above the Fermi level.",
        "positive": "Isospin magnetism and spin-triplet superconductivity in Bernal bilayer\n  graphene: We report the observation of spin-polarized superconductivity in Bernal\nbilayer graphene when doped to a saddle-point van Hove singularity generated by\nlarge applied perpendicular electric field. We observe a cascade of\nelectrostatic gate-tuned transitions between electronic phases distinguished by\ntheir polarization within the isospin space defined by the combination of the\nspin and momentum-space valley degrees of freedom. While all of these phases\nare metallic at zero magnetic field, we observe a transition to a\nsuperconducting state at finite $B_\\parallel\\approx 150$mT applied parallel to\nthe two dimensional sheet. Superconductivity occurs near a symmetry breaking\ntransition, and exists exclusively above the $B_\\parallel$-limit expected of a\nparamagnetic superconductor with the observed $T_C\\approx 30$mK, implying a\nspin-triplet order parameter."
    },
    {
        "anchor": "Atomistic deconstruction of current flow in graphene based\n  hetero-junctions: We describe the numerical modeling of current flow in graphene\nheterojunctions, within the Keldysh Landauer Non-equilibrium Green's function\n(NEGF) formalism. By implementing a $k$-space approach along the transverse\nmodes, coupled with partial matrix inversion using the Recursive Green's\nfunction Algorithm (RGFA), we can simulate on an atomistic scale current flow\nacross devices approaching experimental dimensions. We use the numerical\nplatform to deconstruct current flow in graphene, compare with experimental\nresults on conductance, conductivity and quantum Hall, and deconstruct the\nphysics of electron `optics' and pseudospintronics in graphene $p-n$ junctions.\nWe also demonstrate how to impose exact open boundary conditions along the\nedges to minimize spurious edge reflections.",
        "positive": "Primary thermometry in the intermediate Coulomb blockade regime: We investigate Coulomb blockade thermometers (CBT) in an intermediate\ntemperature regime, where measurements with enhanced accuracy are possible due\nto the increased magnitude of the differential conductance dip. Previous\ntheoretical results show that corrections to the half width and to the depth of\nthe measured conductance dip of a sensor are needed, when leaving the regime of\nweak Coulomb blockade towards lower temperatures. In the present work, we\ndemonstrate experimentally that the temperature range of a CBT sensor can be\nextended by employing these corrections without compromising the primary nature\nor the accuracy of the thermometer."
    },
    {
        "anchor": "Layer effects on the magnetic textures in magnets with local inversion\n  asymmetry: Magnets with broken local inversion symmetries are interesting candidates for\nchiral magnetic textures such as skyrmions and spin spirals. The property of\nthese magnets is that each subsequent layer can possess a different\nDzyaloshniskii-Moriya interaction (DMI) originating from the local inversion\nsymmetry breaking. Given that new candidates of such systems are emerging, with\nthe Van der Waals crystals and magnetic multilayer systems, it is interesting\nto investigate how the chiral magnetic textures depend on the number of layers\nand the coupling between them. In this article, we model the magnetic layers\nwith a classical Heisenberg spin model, where the sign of the DMI alternates\nfor each consecutive layer. We use Monte Carlo simulations to examine chiral\nmagnetic textures and show that the pitch of magnetic spirals is influenced by\nthe interlayer coupling and the number of layers. We observe even-odd effects\nin the number of layers, where we observe a suppression of the spin spirals for\neven layer numbers. We give an explanation for our findings by proposing a net\nDMI in systems with strongly coupled layers. Our results can be used to\ndetermine the DMI in systems with a known number of layers, and for new\ntechnologies based on the tunability of the spiral wave length.",
        "positive": "Band Gap of Strained Graphene Nanoribbons: The band structures of strained graphene nanoribbons (GNRs) are examined by a\ntight binding Hamiltonian that is directly related to the type and strength of\nstrains. Compared to the two-dimensional graphene whose band gap remains close\nto zero even if a large strain is applied, the band gap of graphene nanoribbon\n(GNR) is sensitive to both uniaxial and shears strains. The effect of strain on\nthe electronic structure of a GNR strongly depends on its edge shape and\nstructural indices. For an armchair GNR, uniaxial weak strain changes the band\ngap in a linear fashion, and for a large strain, it results in periodic\noscillation of the band gap. On the other hand, shear strain always tend to\nreduce the band gap. For a zigzag GNR, the effect of strain is to change the\nspin polarization at the edges of GNR, thereby modulate the band gap. A simple\nanalytical model is proposed to interpret the band gap responds to strain in\narmchair GNR, which agrees with the numerical results."
    },
    {
        "anchor": "Dirac and Klein-Gordon particles in one-dimensional periodic potentials: We evaluate the dispersion relation for massless fermions, described by the\nDirac equation, and for zero-spin bosons, described by the Klein-Gordon\nequation, moving in two dimensions and in the presence of a one-dimensional\nperiodic potential. For massless fermions the dispersion relation shows a zero\ngap for carriers with zero momentum in the direction parallel to the barriers\nin agreement with the well-known \"Klein paradox\". Numerical results for the\nenergy spectrum and the density of states are presented. Those for fermions are\nappropriate to graphene in which carriers behave relativistically with the\n\"light speed\" replaced by the Fermi velocity. In addition, we evaluate the\ntransmission through a finite number of barriers for fermions and zero-spin\nbosons and relate it with that through a superlattice.",
        "positive": "Dirac Fermions in Graphite: the State of Art: Macroscopic concentration of massless charge carriers with linear conic\nspectrum - Dirac Fermions (DF) - was shown in 2004 to exist in highly oriented\npyrolytic graphite (HOPG) and governs its electronic properties. These carriers\ncan have the same nature as DF observed in graphite monolayer(graphene) and let\nto view HOPG as superposition of 2D carbon layers, almost independent\nelectronically. We overview here the recent experimental evidences of 2D DF in\ngraphite and their similarity with carriers in graphene."
    },
    {
        "anchor": "Solitonic Josephson thermal transport: We explore the coherent thermal transport sustained by solitons through a\nlong Josephson junction, as a thermal gradient across the system is\nestablished. We observe that a soliton causes the heat current through the\nsystem to increase. Correspondingly, the junction warms up in correspondence of\nthe soliton, with temperature peaks up to, e.g., approximately 56 mK for a\nrealistic Nb-based proposed setup at a bath temperature Tbath = 4.2 K. The\nthermal effects on the dynamics of the soliton are also discussed. Markedly,\nthis system inherits the topological robustness of the solitons. In view of\nthese results, the proposed device can effectively find an application as a\nsuperconducting thermal router in which the thermal transport can be locally\nmastered through solitonic excitations, which positions can be externally\ncontrolled through a magnetic field and a bias current.",
        "positive": "On the Role of Self-Adjointness in the Continuum Formulation of\n  Topological Quantum Phases: Topological quantum phases of matter are characterized by an intimate\nrelationship between the Hamiltonian dynamics away from the edges and the\nappearance of bound states localized at the edges of the system. Elucidating\nthis correspondence in the continuum formulation of topological phases, even in\nthe simplest case of a one-dimensional system, touches upon fundamental\nconcepts and methods in quantum mechanics that are not commonly discussed in\ntextbooks, in particular the self-adjoint extensions of a Hermitian operator.\nWe show how such topological bound states can be derived in a prototypical\none-dimensional system. Along the way, we provide a pedagogical exposition of\nthe self-adjoint extension method as well as the role of symmetries in\ncorrectly formulating the continuum, field-theory description of topological\nmatter with boundaries. Moreover, we show that self-adjoint extensions can be\ncharacterized generally in terms of a conserved local current associated with\nthe self-adjoint operator."
    },
    {
        "anchor": "Low-dimensional phonon transport effects in ultra-narrow, disordered\n  graphene nanoribbons: We investigate the influence of low-dimensionality and disorder in phonon\ntransport in ultra-narrow armchair graphene nanoribbons (GNRs) using\nnon-equilibrium Greens function (NEGF) simulation techniques. We specifically\nfocus on how different parts of the phonon spectrum are influenced by\ngeometrical confinement and line edge roughness. With the introduction of line\nedge roughness, the phonon transmission is reduced, but non-uniformly\nthroughout the spectrum. We identify four distinct behaviors within the phonon\nspectrum in the presence of disorder: i) the low-energy, low-wavevector\nacoustic branches have very long mean-free-paths and are affected the least by\nedge disorder, even in the case of ultra-narrow W=1nm wide GNRs; ii) energy\nregions that consist of a dense population of relatively flat phonon modes\n(including the optical branches) are also not significantly affected, except in\nthe case of the ultranarrow W=1nm GNRs, in which case the transmission is\nreduced because of band mismatch along the phonon transport path; iii)\nquasi-acoustic bands that lie within the intermediate region of the spectrum\nare strongly affected by disorder as this part of the spectrum is depleted of\npropagating phonon modes upon both confinement and disorder especially as the\nchannel length increases; iv) the strongest reduction in phonon transmission is\nobserved in energy regions that are composed of a small density of phonon\nmodes, in which case roughness can introduce transport gaps that greatly\nincrease with channel length. We show that in GNRs of widths as small as W=3nm,\nunder moderate roughness, both the low-energy acoustic modes and dense regions\nof optical modes can retain semi-ballistic transport properties, even for\nchannel lengths up to L=1 um. Modes in the sparse regions of the spectrum fall\ninto the localization regime even for channel lengths as short as 10s of\nnanometers.",
        "positive": "Anomalous Hall Response in Two Dimensional Topological Insulators due to\n  the Stark Effect: It is shown that the presence of matrix dipole moments induced by external\nelectric fields can modify the Hall response in two dimensional Topological\ninsulators. In the case of the Quantum Anomalous Hall effect the induced\ntransverse currents acquire an extra term being proportional to the Hall\nconductance and the time derivative of the applied electric field. In the case\nof the Quantum Spin Hall effect both a spin and charge transverse currents\nappear simultaneously. In virtue of the bulk-edge correspondence the coupling\nbetween the chiral edge channels and the electromagnetic field changes allowing\nfor an extra non minimal coupling term. Both effects can be measured through\ntransport and tunnelling experiments."
    },
    {
        "anchor": "Theory of Spin Hall Magnetoresistance from a Microscopic Perspective: We present a theory of the spin Hall magnetoresistance of metals in contact\nwith magnetic insulators. We express the spin-mixing conductances, which govern\nthe phenomenology of the effect, in terms of the microscopic parameters of the\ninterface and the spin-spin correlation functions of the local moments on the\nsurface of the magnetic insulator. The magnetic field and temperature\ndependence of the spin-mixing conductances leads to a rich behaviour of the\nresistance due to an interplay between the Hanle effect and spin mixing at the\ninterface. Our theory provides a useful tool for understanding the experiments\non heavy metals in contact with magnetic insulators of different kinds, and it\npredicts striking behaviours of magnetoresistance.",
        "positive": "SU(4) and SU(2) Kondo Effects in Carbon Nanotube Quantum Dots: We study the SU(4) Kondo effect in carbon nanotube quantum dots, where doubly\ndegenerate orbitals form 4-electron ``shells''. The SU(4) Kondo behavior is\ninvestigated for one, two and three electrons in the topmost shell. While the\nKondo state of two electrons is quenched by magnetic field, in case of an odd\nnumber of electrons two types of SU(2) Kondo effect may survive. Namely, the\nspin SU(2) state is realized in the magnetic field parallel to the nanotube\n(inducing primarily orbital splitting). Application of the perpendicular field\n(inducing Zeeman splitting) results in the orbital SU(2) Kondo effect."
    },
    {
        "anchor": "Half-Quantized Hall Effect and Power Law Decay of Edge Current\n  Distribution: The half-quantized Hall conductance is characteristic of quantum systems with\nparity anomaly. Here we investigate topological and transport properties of a\nclass of parity anomalous semimetals, in which massive Dirac fermions coexist\nwith massless Dirac fermions in momentum space or real space, and uncovered a\ndistinct bulk-edge correspondence that the half-quantized Hall effect is\nrealized via the bulk massless Dirac fermions while the nontrivial Berry\ncurvature is provided by the massive Dirac fermions. The spatial distribution\nof the edge current decays away from the boundary in a power law instead of an\nexponential law in integer quantum Hall effect. We further address physical\nrelevance of parity anomalous semimetal to three-dimensional semi-magnetic\ntopological insulators and two-dimensional photonic crystals.",
        "positive": "Sensory Organ like Response of Zigzag Edge Graphene Nanoribbons: Using a continuum Dirac theory, we study the density and spin response of\nzigzag edge terminated graphene ribbons subjected to edge potentials and Zeeman\nfields. Our analytical calculations of the density and spin responses of the\nclosed system (fixed particle number) to the static edge fields, show a highly\nnonlinear Weber-Fechner type behavior where the response depends\nlogarithmically on the edge potential. The dependence of the response on the\nsize of the system (e.g. width of a nanoribbon) is also uncovered. Zigzag edge\ngraphene nanoribbons, therefore, provide a realization of response of organs\nsuch as the eye and ear that obey Weber-Fechner law. We validate our analytical\nresults with tight binding calculations. These results are crucial in\nunderstanding important effects of electron-electron interactions in graphene\nnanoribbons such as edge magnetism etc., and also suggest possibilities for\ndevice applications of graphene nanoribbons."
    },
    {
        "anchor": "Large bandgap quantum anomalous hall insulator in a designer\n  ferromagnet-topological insulator-ferromagnet heterostructure: Combining magnetism and nontrivial band topology gives rise to quantum\nanomalous Hall (QAH) insulators and exotic quantum phases such as the QAH\neffect where current flows without dissipation along quantized edge states.\nInducing magnetic order in topological insulators via proximity to a magnetic\nmaterial offers a promising pathway towards achieving QAH effect at high\ntemperature for lossless transport applications. One promising architecture\ninvolves a sandwich structure comprising two single layers of MnBi2Te4 (a 2D\nferromagnetic insulator) with ultra-thin Bi2Te3 in the middle, and is predicted\nto yield a robust QAH insulator phase with a bandgap well above thermal energy\nat room temperature (25 meV). Here we demonstrate the growth of a 1SL MnBi2Te4\n/ 4QL Bi2Te3 /1SL MnBi2Te4 heterostructure via molecular beam epitaxy, and\nprobe the electronic structure using angle resolved photoelectron spectroscopy.\nWe observe strong hexagonally warped massive Dirac Fermions and a bandgap of 75\nmeV. The magnetic origin of the gap is confirmed by the observation of broken\ntime reversal symmetry and the exchange-Rashba effect, in excellent agreement\nwith density functional theory calculations. These findings provide insights\ninto magnetic proximity effects in topological insulators, that will move\nlossless transport in topological insulators towards higher temperature.",
        "positive": "Formation of Hydrocarbons from Hydrogenated Graphene in Circumstellar\n  Clouds: We describe a mechanism that explains the formation of hydrocarbons and\nhydrocarbyls from hydrogenated graphene/graphite; hard C-C bonds are weakened\nand broken by the synergistic effect of chemisorbed hydrogen and high\ntemperature vibrations. Total energies, optimized structures, and transition\nstates are obtained from Density Functional Theory simulations. These values\nhave been used to determine the Boltzman probability for a thermal fluctuation\nto overcome the kinetic barriers, yielding the time scale for an event to\noccur. This mechanism can be used to rationalize the possible routes for the\ncreation of small hydrocarbons and hydrocarbyls from etched graphene/graphite\nin stellar regions."
    },
    {
        "anchor": "Nonlinear Electrical Spin Conversion in a Biased Ferromagnetic Tunnel\n  Contact: The conversion of spin information into electrical signals is indispensable\nfor spintronic technologies. Spin-to-charge conversion in ferromagnetic tunnel\ncontacts is well-described using linear (spin-)transport equations, provided\nthat there is no applied bias, as in nonlocal spin detection. It is shown here\nthat in a biased ferromagnetic tunnel contact, spin detection is strongly\nnonlinear. As a result, the spin-detection efficiency is not equal to the\ntunnel spin polarization. In silicon-based 4-terminal spin-transport devices,\neven a small bias (tens of mV) across the Fe/MgO detector contact enhances the\nspin-detection efficiency to values up to 140 \\% (spin extraction bias) or, for\nspin injection bias, reduces it to almost zero, while, parenthetically, the\ncharge current remains highly spin polarized. Calculations reveal that the\nnonlinearity originates from the energy dispersion of the tunnel transmission\nand the resulting nonuniform energy distribution of the tunnel current,\noffering a route to engineer spin conversion. Taking nonlinear spin detection\ninto account is also shown to explain a multitude of peculiar and puzzling spin\nsignals in structures with a biased detector, including two- and three-terminal\ndevices, and provides a unified, consistent and quantitative description of\nspin signals in devices with a biased and unbiased detector.",
        "positive": "Quantum simulation of Dirac fermion mode, Majorana fermion mode and\n  Majorana-Weyl fermion mode in cavity QED lattice: Quantum simulation aims to simulate a quantum system using a controble\nlaboratory system that underline the same mathematical model. Cavity QED\nlattice system is that prescribe system to simulate the relativistic quantum\neffect. We quantum simulate the Dirac fermion mode, Majorana fermion mode and\nMajorana-Weyl fermion mode and a crossover between them in cavity QED lattice.\nWe also present the different analytical relations between the field operators\nfor different mode excitations."
    },
    {
        "anchor": "Two-dimensional hole transport in ion-gated diamond surfaces: A brief\n  review: Electrically-conducting diamond is a promising candidate for next-generation\nelectronic, thermal and electrochemical applications. One of the major\nobstacles towards its exploitation is the strong degradation that some of its\nkey physical properties - such as the carrier mobility and the superconducting\ntransition temperature - undergo upon the introduction of disorder. This makes\nthe two-dimensional hole gas induced at its surface by electric field-effect\ndoping particularly interesting from both a fundamental and an applied\nperspective, since it strongly reduces the amount of extrinsic disorder with\nrespect to the standard boron substitution. In this short review, we summarize\nthe main results achieved so far in controlling the electric transport\nproperties of different field-effect doped diamond surfaces via the ionic\ngating technique. We analyze how ionic gating can tune their conductivity,\ncarrier density and mobility, and drive the different surfaces across the\ninsulator-to-metal transition. We review their strongly orientation-dependent\nmagnetotransport properties, with a particular focus on the gate-tunable\nspin-orbit coupling shown by the (100) surface. Finally, we discuss the\npossibility of field-induced superconductivity in the (110) and (111) surfaces\nas predicted by density functional theory calculations.",
        "positive": "Minimum Electrical and Thermal Conductivity of Graphene: A\n  Quasiclassical Approach: We investigate the minimum conductivity of graphene within a quasiclassical\napproach taking into account electron-hole coherence effects which stem from\nthe chiral nature of low energy excitations. Relying on an analytical solution\nof the kinetic equation in the electron-hole coherent and incoherent cases we\nstudy both the electrical and thermal conductivity whose relation fullfills\nWiedemann-Franz law. We found that the most of the previous findings based on\nthe Boltzmann equation are restricted to only high mobility samples where\nelectron-hole coherence effects are not sufficient."
    },
    {
        "anchor": "Nonlocal electrodynamics in Weyl semi-metals: Recently synthesized 3D materials with Dirac spectrum exhibit peculiar\nelectric transport qualitatively different from its 2D analogue, graphene.\nNeglecting impuritiy scattering, the real part of the conductivity is strongly\nfrequency dependent (linear), while the imaginary part is non-zero (unlike in\nundoped, clean graphene). The Coulomb interaction between electrons is\nunscreened as in a dielectric and hence is long range. We demonstrate that the\ninteraction correction renders the electrodynamics nonlocal on a mesoscopic\\\nscale. The longitudinal conductivity $\\sigma _{L}$ (related by charge\nconservation to the electric susceptibility) and the transverse conductivity\n$\\sigma _{T}$ are different in the long wave length limit and consequently the\nstandard local Ohm's law description does not apply. This leads to several\nremarkable effects in transport and optical response. We predict a charging\neffect in DC transport that is a direct signature of the nonlocality. The\noptical response of the WSM is also sensitive to the nonlocality. In these\nmaterials p-polarized light generates bulk plasmons as well as the transversal\nwaves. The propagation inside the WSM is only slightly attenuated. At a\nspecific (material parameter dependent) frequency the two modes coincide, a\nphenomenon impossible in a local medium. Remarkably, for any frequency there is\nan incident angle where total absorption occurs, turning the WSM opaque.",
        "positive": "Giant and Broadband THz and IR Emission in Drift-biased Graphene-Based\n  Hyperbolic Nanostructures: We demonstrate that Cherenkov radiation can be manipulated in terms of\noperation frequency, bandwidth, and efficiency by simultaneously controlling\nthe properties of drifting electrons and the photonic states supported by their\nsurrounding media. We analytically show that the radiation rate strongly\ndepends on the momentum of the excited photonic state, in terms of magnitude,\nfrequency dispersion, and its variation versus the properties of the drifting\ncarriers. This approach is applied to design and realize miniaturized,\nbroadband, tunable, and efficient terahertz and far-infrared sources by\nmanipulating and boosting the coupling between drifting electrons and\nengineered hyperbolic modes in graphene-based nanostructures. The broadband,\ndispersive, and confined nature of hyperbolic modes relax momentum matching\nissues, avoid using electron beams, and drastically enhance the radiation rate\n- allowing that over 90% of drifting electrons emit photons. Our findings open\na new paradigm for the development of solid-state terahertz and infrared\nsources."
    },
    {
        "anchor": "Spiderweb nanomechanical resonators via Bayesian optimization: inspired\n  by nature and guided by machine learning: From ultra-sensitive detectors of fundamental forces to quantum networks and\nsensors, mechanical resonators are enabling next-generation technologies to\noperate in room temperature environments. Currently, silicon nitride\nnanoresonators stand as a leading microchip platform in these advances by\nallowing for mechanical resonators whose motion is remarkably isolated from\nambient thermal noise. However, to date, human intuition has remained the\ndriving force behind design processes. Here, inspired by nature and guided by\nmachine learning, a spiderweb nanomechanical resonator is developed that\nexhibits vibration modes which are isolated from ambient thermal environments\nvia a novel \"torsional soft-clamping\" mechanism discovered by the data-driven\noptimization algorithm. This bio-inspired resonator is then fabricated;\nexperimentally confirming a new paradigm in mechanics with quality factors\nabove 1 billion in room temperature environments. In contrast to other\nstate-of-the-art resonators, this milestone is achieved with a compact design\nwhich does not require sub-micron lithographic features or complex phononic\nbandgaps, making it significantly easier and cheaper to manufacture at large\nscales. Here we demonstrate the ability of machine learning to work in tandem\nwith human intuition to augment creative possibilities and uncover new\nstrategies in computing and nanotechnology.",
        "positive": "Cryogen-free scanning gate microscope for the characterization of\n  Si/Si$_{0.7}$Ge$_{0.3}$ quantum devices at milli-Kelvin temperatures: Silicon can be isotopically enriched, allowing for the fabrication of highly\ncoherent semiconductor spin qubits. However, the conduction band of bulk Si\nexhibits a six-fold valley degeneracy, which may adversely impact the\nperformance of silicon quantum devices. To date, the spatial characterization\nof valley states in Si remains limited. Moreover, techniques for probing valley\nstates in functional electronic devices are needed. We describe here a\ncryogen-free scanning gate microscope for the characterization of\nSi/Si$_{0.7}$Ge$_{0.3}$ quantum devices at mK temperatures. The microscope is\nbased on the Pan-walker design, with coarse positioning piezo stacks and a fine\nscanning piezo tube. A tungsten microscope tip is attached to a tuning fork for\nactive control of the tip-to-sample distance. To reduce vibration noise from\nthe pulse tube cooler, we utilize both active and passive vibration isolation\nmechanisms, and achieve a root-mean-square noise in $z$ of $\\sim$ 2 nm. Our\nmicroscope is designed to characterize fully functioning\nSi/Si$_{0.7}$Ge$_{0.3}$ quantum devices. As a proof of concept, we use the\nmicroscope to manipulate the charge occupation of a Si quantum dot, opening up\na range of possibilities for the exploration of quantum devices and materials."
    },
    {
        "anchor": "Confinement effects on the configurational order of monodisperse disk\n  packings: Monodisperse circular disks have been collectively packed in confined\ngeometries using a Monte Carlo method where the compaction is propelled by two-\ndimensional stochastic agitation. We have found that confinement (i.e.,\nfinite-size plus surface effects) determines the symmetry of the packed\nconfigurations together with the size evolution of the probability density of\nthe packing fraction. For the particular case of small systems in square\ncontainers, the probability density of the packing fraction shows several\nwell-defined peaks, depending on the system size, for both hard- wall and\nperiodic boundary conditions. High-symmetry configurations (other than the\nn\\timesn square arrays) with non-negligible occurrence probabilities are found\nas a direct consequence of monodispersity and confinement.",
        "positive": "Room-temperature gating of molecular junctions using few-layer graphene\n  nanogap electrodes: We report on a method to fabricate and measure gateable molecular junctions\nwhich are stable at room temperature. The devices are made by depositing\nmolecules inside a few-layer graphene nanogap, formed by feedback controlled\nelectroburning. The gaps have separations on the order of 1-2 nm as estimated\nfrom a Simmons model for tunneling. The molecular junctions display gateable\nIV-characteristics at room temperature."
    },
    {
        "anchor": "Current noise cross correlation mediated by Majorana bound states: We study the transport properties of a quantum dot-Majorana hybrid system, in\nwhich each of paired Majorana bound states is connected to one quantum dot.\nWith the help of non-equilibrium Green's function method, we obtain an exact\nsolution of the Green's functions and calculate the currents through the\nquantum dots and nonlocal noise cross correlation between the currents. As a\nfunction of dot energy levels $\\epsilon_{1}$ and $\\epsilon_{2}$, we find that\nfor the symmetric level configuration $\\epsilon_{1}=\\epsilon_{2}$, the noise\ncross correlation is negative in the low lead voltage regime, while it becomes\npositive with the increase of the lead voltages. Due to the particle-hole\nsymmetry, the cross correlation is always positive in the anti-symmetric case\n$\\epsilon_{1}=-\\epsilon_{2}$. In contrast, the cross correlation of\nnon-Majorana setups is always positive. For comparison, we also perform the\ndiagonalized master equation calculation to check its applicability. It is\nfound that the diagonalized master equations work well in most regimes of\nsystem parameters. Nevertheless, it shows an obvious deviation from the exact\nsolution by the non-equilibrium Green's function method when all eigenenergies\nof the dot-Majorana hybrid system and simultaneously the energy intervals are\ncomparable to the dot-lead coupling strength.",
        "positive": "Multiple higher-order topological phases with even and odd pairs of\n  zero-energy corner modes in a $C_3$ symmetry broken model: The higher-order corner modes for quantum anomalous Hall insulators in $C_3$\nsymmetry broken honeycomb lattice have been engineered recently. Here we\nconsider an extended Haldane model in presence of inversion symmetry breaking\nsub-lattice mass, time-reversal symmetry breaking Zeeman field and spin-orbit\ncoupling interaction where we find that only the quantum spin Hall insulator\ncan host the second-order dipolar phase while the remaining two first-order\ntopological phases do not morph into the latter. Remarkably, four-fold\ndegeneracy of zero-energy dipolar states can be reduced to two-fold under the\napplication (withdrawn) of sub-lattice mass (Zeeman field) term when the\nspin-orbit coupling is already present. On the other hand, the sub-lattice mass\nand Zeeman field terms compete with each other to pin down the two mid-gap\nstates at zero-energy in the absence or presence of spin-orbit coupling.\nInterestingly, the bulk-polarization can topologically characterize the dipolar\nphase irrespective of the energy of the mid-gap states as long as inversion\nsymmetry is preserved. The effective gap criterion can qualitatively mimic the\nextent of SOT phase originated by the interplay between finite Zeeman exchange\nfield, sub-lattice mass, and SOC interaction."
    },
    {
        "anchor": "Electron states in the quantum wire with periodic serial structure: A model quantum wire embedded in a matrix permeable to electron waves is\ninvestigated in terms of electronic states. The wire is assumed to have a 1D\ncrystal structure. Through electron waves propagating in its surroundings,\nlateral modes are coupled with Bloch waves propagating along the wire axis,\nwhich results in modes splitting into multiplets. The results presented in this\nstudy have been obtained by direct solution of the Schrodinger equation in the\neffective mass approximation.",
        "positive": "Effects of Quantum Hall Edge Reconstruction on Momenum-Resolved\n  Tunneling: During the reconstruction of the edge of a quantum Hall liquid, Coulomb\ninteraction energy is lowered through the change in the structure of the edge.\nWe use theory developed earlier by one of the authors [K. Yang, Phys. Rev.\nLett. 91, 036802 (2003)] to calculate the electron spectral functions of a\nreconstructed edge, and study the consequences of the edge reconstruction for\nthe momentum-resolved tunneling into the edge. It is found that additional\nexcitation modes that appear after the reconstruction produce distinct features\nin the energy and momentum dependence of the spectral function, which can be\nused to detect the presence of edge reconstruction."
    },
    {
        "anchor": "Theory of Spin Torque Assisted Thermal Switching of Single Free Layer: The spin torque assisted thermal switching of the single free layer was\nstudied theoretically. Based on the rate equation, we derived the theoretical\nformulas of the most likely and mean switching currents of the sweep current\nassisted magnetization switching, and found that the value of the exponent $b$\nin the switching rate formula significantly affects the estimation of the\nretention time of magnetic random access memory. Based on the Fokker-Planck\napproach, we also showed that the value of $b$ should be two, not unity as\nargued in the previous works.",
        "positive": "Spin independence of the strongly enhanced effective mass in ultra-clean\n  SiGe/Si/SiGe two-dimensional electron system: The effective mass at the Fermi level is measured in the strongly interacting\ntwo-dimensional (2D) electron system in ultra-clean SiGe/Si/SiGe quantum wells\nin the low-temperature limit in tilted magnetic fields. At low electron\ndensities, the effective mass is found to be strongly enhanced and independent\nof the degree of spin polarization, which indicates that the mass enhancement\nis not related to the electrons' spins. The observed effect turns out to be\nuniversal for silicon-based 2D electron systems, regardless of random\npotential, and cannot be explained by existing theories."
    },
    {
        "anchor": "Time-resolved detection of spin-transfer-driven ferromagnetic resonance\n  and spin torque measurement in magnetic tunnel junctions: Several experimental techniques have been introduced in recent years in\nattempts to measure spin transfer torque in magnetic tunnel junctions (MTJs).\nThe dependence of spin torque on bias is important for understanding\nfundamental spin physics in magnetic devices and for applications. However,\nprevious techniques have provided only indirect measures of the torque and\ntheir results to date for the bias dependence are qualitatively and\nquantitatively inconsistent. Here we demonstrate that spin torque in MTJs can\nbe measured directly by using time-domain techniques to detect resonant\nmagnetic precession in response to an oscillating spin torque. The technique is\naccurate in the high-bias regime relevant for applications, and because it\ndetects directly small-angle linear-response magnetic dynamics caused by spin\ntorque it is relatively immune to artifacts affecting competing techniques. At\nhigh bias we find that the spin torque vector differs markedly from the simple\nlowest-order Taylor series approximations commonly assumed.",
        "positive": "Quantum-Limited Amplification via Reservoir Engineering: We describe a new kind of phase-preserving quantum amplifier which utilizes\ndissipative interactions in a parametrically-coupled three-mode bosonic system.\nThe use of dissipative interactions provides a fundamental advantage over\nstandard cavity-based parametric amplifiers: large photon number gains are\npossible with quantum-limited added noise, with no limitation on the\ngain-bandwidth product. We show that the scheme is simple enough to be\nimplemented both in optomechanical systems and in superconducting microwave\ncircuits."
    },
    {
        "anchor": "Connecting wave functions at a three-leg junction of one-dimensional\n  channels: We propose a scheme to connect the wave functions on different\none-dimensional branches of a three-leg junction (Y-junction). Our scheme\ndiffers from that due to Griffith [Trans. Faraday Soc. 49, 345 (1953)] in the\nrespect that ours can model the difference in the widths of the\nquasi-one-dimensional channels in different systems. We test our scheme by\ncomparing results from a doubly-connected one-dimensional system and a related\nquasi-one-dimensional system, and we find a good agreement. Therefore our\nscheme may be useful in the construction of one-dimensional effective theories\nout of (multiply-connected) quasi-one-dimensional systems.",
        "positive": "The Stationary Phase Method for a Wave Packet in a Semiconductor Layered\n  System. The applicability of the method: Using the formal analysis made by Bohm in his book, {\\em \"Quantum theory\"},\nDover Publications Inc. New York (1979), to calculate approximately the phase\ntime for a transmitted and the reflected wave packets through a potential\nbarrier, we calculate the phase time for a semiconductor system formed by\ndifferent mesoscopic layers. The transmitted and the reflected wave packets are\nanalyzed and the applicability of this procedure, based on the stationary phase\nof a wave packet, is considered in different conditions. For the applicability\nof the stationary phase method an expression is obtained in the case of the\ntransmitted wave depending only on the derivatives of the phase, up to third\norder. This condition indicates whether the parameters of the system allow to\ndefine the wave packet by its leading term. The case of a multiple barrier\nsystems is shown as an illustration of the results. This formalism includes the\nuse of the Transfer Matrix to describe the central stratum, whether it is\nformed by one layer (the single barrier case), or two barriers and an inner\nwell (the DBRT system), but one can assume that this stratum can be comprise of\nany number or any kind of semiconductor layers."
    },
    {
        "anchor": "Ordering effect of Coulomb interaction in ballistic double-ring systems: We study a model of two concentric onedimensional rings with incommensurate\nareas $A_1$ and $A_2$, in a constant magnetic field. The two rings are coupled\nby a nonhomogeneous inter-ring tunneling amplitude, which makes the\none-particle spectrum chaotic. For noninteracting particles the energy of the\nmany-body ground state and the first excited state exhibit random fluctuations\ncharacterized by the Wigner-Dyson statistics. In contrast, we show that the\nelectron-electron interaction orders the magnetic field dependence of these\nquantities, forcing them to become periodic functions, with period $ \\propto\n1/(A_1 + A_2)$. In such a strongly correlated system the only possible source\nof disorder comes from charge fluctuations, which can be controlled by a\ntunable inter-ring gate voltage.",
        "positive": "Heterostructures of graphene and topological insulators Bi$_2$Se$_3$,\n  Bi$_2$Te$_3$, and Sb$_2$Te$_3$: Prototypical three-dimensional topological insulators of the Bi$_2$Se$_3$\nfamily provide a beautiful example of the appearance of the surface states\ninside the bulk band gap caused by spin-orbit coupling-induced topology. The\nsurface states are protected against back scattering by time reversal symmetry,\nand exhibit spin-momentum locking whereby the electron spin is polarized\nperpendicular to the momentum, typically in the plane of the surface. On the\nother hand, graphene is a prototypical two-dimensional material, with\nnegligible spin-orbit coupling. When graphene is placed on the surface of a\ntopological insulator, giant spin-orbit coupling is induced by the proximity\neffect, enabling interesting novel electronic properties of its Dirac\nelectrons. We present a detailed theoretical study of the proximity effects of\nmonolayer graphene and topological insulators Bi$_2$Se$_3$, Bi$_2$Te$_3$, and\nSb$_2$Te$_3$, and elucidate the appearance of the qualitatively new spin-orbit\nsplittings well described by a phenomenological Hamiltonian, by analyzing the\norbital decomposition of the involved band structures. This should be useful\nfor building microscopic models of the proximity effects between the surfaces\nof the topological insulators and graphene."
    },
    {
        "anchor": "Three-Dimensional Wave Packet Approach for the Quantum Transport of\n  Atoms through Nanoporous Membranes: Quantum phenomena are relevant to the transport of light atoms and molecules\nthrough nanoporous two-dimensional (2D) membranes. Indeed, confinement provided\nby (sub-)nanometer pores enhances quantum effects such as tunneling and zero\npoint energy (ZPE), even leading to quantum sieving of different isotopes of a\ngiven element. However, these features are not always taken into account in\napproaches where classical theories or approximate quantum models are\npreferred. In this work we present an exact three-dimensional wave packet\npropagation treatment for simulating the passage of atoms through periodic 2D\nmembranes. Calculations are reported for the transmission of $^3$He and $^4$He\nthrough graphdiyne as well as through a holey graphene model. For\nHe-graphdiyne, estimations based on tunneling-corrected transition state theory\nare correct: both tunneling and ZPE effects are very important but competition\nbetween each other leads to a moderately small $^4$He/$^3$He selectivity. Thus,\nformulations that neglect one or another quantum effect are inappropriate. For\nthe transport of He isotopes through leaky graphene, the computed transmission\nprobabilities are highly structured suggesting widespread selective adsorption\nresonances and the resulting rate coefficients and selectivity ratios are not\nin agreement with predictions from transition state theory. Present approach\nserves as a benchmark for studies of the range of validity of more approximate\nmethods.",
        "positive": "Fluctuation-induced currents in suspended graphene nanoribbons:\n  Adiabatic quantum pumping approach: Graphene nanoribbons (GNRs) are thin strips of graphene with unique\nproperties due to their structure and nanometric dimensions. They stand out as\nbasic components for the construction of different types of\nnanoelectromechanical systems (NEMS), including some very promising sensors and\npumps. However, various phenomena, such as unintended mechanical vibrations,\ncan induce undesired electrical currents in these devices. Here, we take a\nquantum mechanical approach to analyze how currents induced by fluctuations\n(either thermal or of some other kind) in suspended GNRs contribute to the\nelectric current. In particular, we study the pumping current induced by the\nadiabatic variation of the Hamiltonian of the system when a transverse\nvibration (flexural mode) of a GNR suspended over a gate is excited. Our\ntheoretical approach and results provide useful tools and rules of thumb to\nunderstand and control the charge current induced by fluctuations in GNR-based\nNEMS, which is important for their applications in nanoscale sensors, pumps,\nand energy harvesting devices."
    },
    {
        "anchor": "Graphene on two-dimensional hexagonal BN, AlN, and GaN: Electronic,\n  spin-orbit, and spin relaxation properties: We investigate the electronic structure of graphene on a series of 2D\nhexagonal nitride insulators hXN, X = B, Al, and Ga, with DFT calculations. A\nsymmetry-based model Hamiltonian is employed to extract orbital parameters and\nspin-orbit coupling (SOC) from the low-energy Dirac bands of proximitized\ngraphene. While commensurate hBN induces a staggered potential of about 10 meV\ninto the Dirac bands, less lattice-matched hAlN and hGaN disrupt the Dirac\npoint much less, giving a staggered gap below 100 $\\mu$eV. Proximitized\nintrinsic SOC surprisingly does not increase much above the pristine graphene\nvalue of 12 $\\mu$eV; it stays in the window of (1-16) $\\mu$eV, depending\nstrongly on stacking. However, Rashba SOC increases sharply when increasing the\natomic number of the boron group, with calculated maximal values of 8, 15, and\n65 $\\mu$eV for B, Al, and Ga-based nitrides, respectively. The individual\nRashba couplings also depend strongly on stacking, vanishing in\nsymmetrically-sandwiched structures, and can be tuned by a transverse electric\nfield. The extracted spin-orbit parameters were used as input for spin\ntransport simulations based on Chebyshev expansion of the time-evolution of the\nspin expectation values, yielding interesting predictions for the electron spin\nrelaxation. Spin lifetime magnitudes and anisotropies depend strongly on the\nspecific (hXN)/graphene/hXN system, and they can be efficiently tuned by an\napplied external electric field as well as the carrier density in the graphene\nlayer. A particularly interesting case for experiments is graphene/hGaN, in\nwhich the giant Rashba coupling is predicted to induce spin lifetimes of 1-10\nns, short enough to dominate over other mechanisms, and lead to the same spin\nrelaxation anisotropy as observed in conventional semiconductor\nheterostructures: 50\\%, meaning that out-of-plane spins relax twice as fast as\nin-plane spins.",
        "positive": "Ultrafast reflectivity modulation in AlGaAs/InAlGaAs multiple quantum\n  well photonic crystal waveguides: We report an ultrafast optical tuning of the reflectivity of AlGaAs/InAlGaAs\nmultiple quantum well photonic crystal waveguides using a reflection geometry,\npump-probe technique."
    },
    {
        "anchor": "Large-scale transfer and characterization of macroscopic periodically\n  nano-rippled graphene: Nano-rippled graphene, a structurally modified graphene, presents a novel\nmaterial with a large range of possible applications including sensors,\nelectrodes, coatings, optoelectronics, spintronics and straintronics. In this\nwork we have synthesized macroscopic single layer graphene with well-defined\nuniaxial periodic modulation on a stepped Ir(332) substrate and transferred it\nto a dielectric support. The applied fast transfer process does not damage the\nIr crystal which can be repeatedly used for graphene synthesis. Upon transfer,\na millimeter sized graphene flake with a uniform periodic nano-ripple structure\nis obtained, which exhibits a macroscopically measurable uniaxial strain. The\nperiodic one dimensional arrangement of graphene ripples was confirmed by\natomic force microscopy and polarized Raman measurements. An important feature\nof this system is that the graphene lattice is rotated in several different,\nwell-defined orientations with respect to the direction of the ripple induced\nuniaxial strain. Moreover, geometry of the ripples can be modified by changing\nthe graphene synthesis parameters.",
        "positive": "Non-equilibrium Transport in dissipative one-dimensional Nanostructures: We study the non-equilibrium transport properties of a one-dimensional array\nof dissipative quantum dots. Using the Keldysh formalism, we show that the\ndots' dissipative nature leads to a spatial variation of the chemical\npotential, which in disordered arrays, breaks the invariance of the current, I,\nunder bias reversal. Moreover, the array's nanoscopic size results in an\nalgebraic low-temperature dependence of I. Finally, we show that a local\nCoulomb interaction splits the dots' electronic levels, resulting in a Coulomb\nblockade, which is softened with increasing dissipation and array size."
    },
    {
        "anchor": "Evidence of Cooper pair pumping with combined flux and voltage control: We have experimentally demonstrated pumping of Cooper pairs in a\nsingle-island mesoscopic structure. The island was connected to leads through\nSQUID (Superconducting Quantum Interference Device) loops. Synchronized flux\nand voltage signals were applied whereby the Josephson energies of the SQUIDs\nand the gate charge were tuned adiabatically. From the current-voltage\ncharacteristics one can see that the pumped current increases in 1e steps which\nis due to quasiparticle poisoning on the measurement time scale, but we argue\nthat the transport of charge is due to Cooper pairs.",
        "positive": "Competition of magneto-dipole, anisotropy and exchange interactions in\n  composite multiferroics: We study the competition of magneto-dipole, anisotropy and exchange\ninteractions in composite three dimensional multiferroics. Using Monte Carlo\nsimulations we show that magneto-dipole interaction does not suppress the\nferromagnetic state caused by the interaction of the ferroelectric matrix and\nmagnetic subsystem. However, the presence of magneto-dipole interaction\ninfluences the order-disorder transition: depending on the strength of\nmagneto-dipole interaction the transition from the ferromagnetic to the\nsuperparamagnetic state is accompanied either by creation of vortices or\ndomains of opposite magnetization. We show that the temperature hysteresis loop\noccurs due to non-monotonic behavior of exchange interaction versus\ntemperature. The origin of this hysteresis is related to the presence of stable\nmagnetic domains which are robust against thermal fluctuations."
    },
    {
        "anchor": "Method for finding the critical temperature of the island in a SET\n  structure: We present a method to measure the critical temperature of the island of a\nsuperconducting single electron transistor. The method is based on a sharp\nchange in the slope of the zero-bias conductance as a function of temperature.\nWe have used this method to determine the superconducting phase transition\ntemperature of the Nb island of an superconducting single electron transistor\nwith Al leads. We obtain $T_\\mathrm{c}^\\mathrm{Nb}$ as high as 8.5 K and gap\nenergies up to $\\Delta_\\mathrm{Nb}\\simeq 1.45$ meV. By looking at the zero bias\nconductance as a function of magnetic field instead of temperature, also the\ncritical field of the island can be determined. Using the orthodox theory, we\nhave performed extensive numerical simulations of charge transport properties\nin the SET at temperatures comparable to the gap, which match very well the\ndata, therefore providing a solid theoretical basis for our method.",
        "positive": "Spin-transfer torque-driven motion, deformation, and instabilities of\n  magnetic skyrmions at high currents: In chiral magnets, localized topological magnetic whirls, magnetic skyrmions,\ncan be moved by spin polarized electric currents. Upon increasing the current\nstrength, with prospects for high-speed skyrmion motion for spintronics\napplications in mind, isolated skyrmions deform away from their typical\ncircular shape. We analyze the influence of spin-transfer torques on the shape\nof a single skyrmion, including its stability upon adiabatically increasing the\nstrength of the applied electric current. For rather compact skyrmions at\nuniaxial anisotropies well above the critical anisotropy for domain wall\nformation, we find for high current densities that the skyrmion assumes a\nnon-circular shape with a tail, reminiscent of a shooting star. For larger and\nhence softer skyrmions close to the critical anisotropy, in turn, we observe a\ncritical current density above which skyrmions become unstable. We show that\nabove a second critical current density the shooting star solution can be\nrecovered also for these skyrmions."
    },
    {
        "anchor": "Geometrical properties of the ground state manifold in the spin boson\n  model: Geometrical and topological properties of quantum ground state manifolds\npermits to characterize phases of matter, and identify phase transitions. Here,\nwe study the effect of a quantum dissipative environment on the geometrical\nproperties of the ground state manifold of a single spin 1/2 in an external\neffective magnetic field. We show that the quantum phase transition at zero\ntemperature in the model is associated with a universal metric singularity\nrelated to the divergence of the spin susceptibility. The absence of transition\nat finite temperature corresponds to a smooth variation of the associated\nmetric with temperature, without singular points.",
        "positive": "Evidence for Half-Metallicity in n-type HgCr2Se4: High quality HgCr$_2$Se$_4$ single crystals have been investigated by\nmagnetization, electron transport and Andreev reflection spectroscopy. In the\nferromagnetic ground state, the saturation magnetic moment of each unit cell\ncorresponds to an integer number of electron spins (3 $\\mu_B$/Cr$^{3+}$), and\nthe Hall effect measurements suggest n-type charge carriers. Spin polarizations\nas high as $97\\%$ were obtained from fits of the differential conductance\nspectra of HgCr$_2$Se$_4$/Pb junctions with the modified\nBlonder-Tinkham-Klapwijk (BTK) theory. The temperature and bias-voltage\ndependencies of the sub-gap conductance are consistent with recent theoretical\ncalculations based on spin active scatterings at a superconductor/half metal\ninterface. Our results suggest that n-HgCr$_2$Se$_4$ is a half metal, in\nagreement with theoretical calculations that also predict undoped\nHgCr$_2$Se$_4$ is a magnetic Weyl semimetal."
    },
    {
        "anchor": "Observation of electric current induced by optically injected spin\n  current: A normally incident light of linear polarization injects a pure spin current\nin a strip of 2-dimensional electron gas with spin-orbit coupling. We report\nobservation of an electric current with a butterfly-like pattern induced by\nsuch a light shed on the vicinity of a crossbar shaped InGaAs/InAlAs quantum\nwell. Its light polarization dependence is the same as that of the spin\ncurrent. We attribute the observed electric current to be converted from the\noptically injected spin current caused by scatterings near the crossing. Our\nobservation provides a realistic technique to detect spin currents, and opens a\nnew route to study the spin-related science and engineering in semiconductors.",
        "positive": "Quantum feedback control of a superconducting qubit: Persistent Rabi\n  oscillations: The act of measurement bridges the quantum and classical worlds by projecting\na superposition of possible states into a single, albeit probabilistic,\noutcome. The time-scale of this \"instantaneous\" process can be stretched using\nweak measurements so that it takes the form of a gradual random walk towards a\nfinal state. Remarkably, the interim measurement record is sufficient to\ncontinuously track and steer the quantum state using feedback. We monitor the\ndynamics of a resonantly driven quantum two-level system -- a superconducting\nquantum bit --using a near-noiseless parametric amplifier. The high-fidelity\nmeasurement output is used to actively stabilize the phase of Rabi\noscillations, enabling them to persist indefinitely. This new functionality\nshows promise for fighting decoherence and defines a path for continuous\nquantum error correction."
    },
    {
        "anchor": "Quantization of entropy in a quasi-two-dimensional electron gas: We demonstrate that the partial entropy of a two-dimensional electron gas\n(2DEG) exhibits quantized peaks at resonances between the chemical potential\nand electron levels of size quantization. In the limit of no scattering, the\npeaks depend only on the subband quantization number and are independent on\nmaterial parameters, shape of the confining potential, electron effective mass\nand temperature. The quantization of partial entropy is a signature of a\ntopological phase transition in a 2DEG. In the presence of stationary disorder,\nthe magnitude of peaks decreases. Its deviation from the quantized values is a\ndirect measure of the disorder induced smearing of the electronic density of\nstates.",
        "positive": "Orbitally controlled quantum Hall states in decoupled two-bilayer\n  graphene sheets: We report on integer and fractional quantum Hall states in a stack of two\ntwisted Bernal bilayer graphene sheets. By exploiting the momentum mismatch in\nreciprocal space, we suppress single particle tunneling between both bilayers.\nSince the bilayers are spatially separated by only 0.34 nm, the stack benefits\nfrom strong interlayer Coulomb interactions. These interactions can cause the\nformation of a Bose-Einstein condensate. Indeed, such a condensate is observed\nfor half filling in each bilayer sheet. However, only when the partially filled\nlevels have orbital index 1. It is absent for partially filled levels with\norbital index 0. This discrepancy is tentatively attributed to the role of\nskyrmion/anti-skyrmion pair excitations and the dependence of the energy of\nthese excitations on the orbital index. The application of asymmetric top and\nbottom gate voltages enables to influence the orbital nature of the electronic\nstates of the graphene bilayers at the chemical potential and to navigate in an\norbital mixed space. The latter hosts an even denominator fractional quantum\nHall state at total filling -3/2. Our observations suggest a unique edge\nreconstruction involving both electrons and chiral p-wave composite fermions."
    },
    {
        "anchor": "Substrate induced nanoscale resistance variation in epitaxial graphene: Graphene, the first true two-dimensional material still reveals the most\nremarkable transport properties among the growing class of two-dimensional\nmaterials. Although many studies have investigated fundamental scattering\nprocesses, the surprisingly large variation in the experimentally determined\nresistances associated with a localized defect is still an open issue. Here, we\nquantitatively investigate the local transport properties of graphene prepared\nby polymer assisted sublimation growth (PASG) using scanning tunneling\npotentiometry. PASG graphene is characterized by a spatially homogeneous\ncurrent density, which allows to analyze variations in the local\nelectrochemical potential with high precision. We utilize this possibility by\nexamining the local sheet resistance finding a significant variation of up to\n270% at low temperatures. We identify a correlation of the sheet resistance\nwith the stacking sequence of the 6H-SiC substrate as well as with the distance\nbetween the graphene sheet and the substrate. Our results experimentally\nquantify the strong impact of the graphene-substrate interaction on the local\ntransport properties of graphene.",
        "positive": "Perfect Coulomb drag and exciton transport in an excitonic insulator: Strongly coupled two-dimensional electron-hole bilayers can give rise to\nnovel quantum Bosonic states: electrons and holes in electrically isolated\nlayers can pair into interlayer excitons, which can form a Bose-Einstein\ncondensate below a critical temperature at zero magnetic field. This state is\npredicted to feature perfect Coulomb drag, where a current in one layer must be\naccompanied by an equal but opposite current in the other, and counterflow\nsuperconductivity, where the excitons form a superfluid with zero viscosity.\nElectron-hole bilayers in the strong coupling limit with an excitonic insulator\nground state have been recently achieved in semiconducting transition metal\ndichalcogenide heterostructures, but direct electrical transport measurements\nremain challenging. Here we use a novel optical spectroscopy to probe the\nelectrical transport of correlated electron-hole fluids in MoSe2/hBN/WSe2\nheterostructures. We observe perfect Coulomb drag in the excitonic insulator\nphase up to a temperature as high as ~15K. Strongly correlated electron and\nhole transport is also observed at unbalanced electron and hole densities,\nalthough the Coulomb drag is not perfect anymore. Meanwhile, the counterflow\nresistance of interlayer excitons remains finite. These results indicate the\nformation of an exciton gas in the excitonic insulator which does not\ncondensate into a superfluid at low temperature. Our work also demonstrates\nthat dynamic optical spectroscopy provides a powerful tool for probing novel\nexciton transport behavior and possible exciton superfluidity in correlated\nquantum electron-hole fluids."
    },
    {
        "anchor": "Scanning gate microscopy of current-annealed single layer graphene: We have used scanning gate microscopy to explore the local conductivity of a\ncurrent-annealed graphene flake. A map of the local neutrality point (NP) after\nannealing at low current density exhibits micron-sized inhomogeneities.\nBroadening of the local e-h transition is also correlated with the\ninhomogeneity of the NP. Annealing at higher current density reduces the NP\ninhomogeneity, but we still observe some asymmetry in the e-h conduction. We\nattribute this to a hole doped domain close to one of the metal contacts\ncombined with underlying striations in the local NP.",
        "positive": "Time-energy filtering of single electrons in ballistic waveguides: Characterizing distinct electron wave packets is a basic task for solid-state\nelectron quantum optics with applications in quantum metrology and sensing. A\nimportant circuit element for this task is a non-stationary potential barrier\nthan enables backscattering of chiral particles depending on their energy and\ntime of arrival. Here we solve the quantum mechanical problem of\nsingle-particle scattering by a ballistic constriction in an fully depleted\nquantum Hall system under spatially uniform but time-dependent electrostatic\npotential modulation. The result describes electrons distributed in time-energy\nspace according to a modified Wigner quasiprobability distribution and\nscattered with an energy-dependent transmission probability that characterizes\nconstriction in the absence of modulation. Modification of the incoming Wigner\ndistribution due to external time-dependent potential simplifies in case of\nlinear time-dependence and admits semiclassical interpretation. Our results\nsupport a recently proposed and implemented method for measuring time and\nenergy distribution of solitary electrons as a quantum tomography technique,\nand offer new paths for experimental exploration of on-demand sources of\ncoherent electrons."
    },
    {
        "anchor": "Toward high-fidelity coherent electron spin transport in a GaAs double\n  quantum dot: In this paper, we investigate how to achieve high-fidelity electron spin\ntransport in a GaAs double quantum dot. Our study examines spin transport from\nmultiple perspectives. We first study how a double dot potential may\naffect/accelerate spin relaxation. We calculate spin relaxation rate in a wide\nrange of experimental parameters and focus on the occurrence of spin hot spots.\nA safe parameter regime is identified in order to avoid these spin hot spots.\nWe also study the non-adiabatic transitions in the Landau-Zener process of\nsweeping the interdot detuning, and propose a scheme to take advantage of\npossible Landau-Zener-St\\\"{u}kelburg interference to achieve high-fidelity spin\ntransport at a higher speed. Finally, we calculate the double-dot correction on\nthe effective $g$-factor for the tunneling electron, and estimate the resulting\nphase error between different spin states. Our results should provide a useful\nguidance for future experiments on coherent electron spin transport.",
        "positive": "Transport of neutral optical excitations using electric fields: Mobile quantum impurities interacting with a fermionic bath form\nquasiparticles known as Fermi polarons. We demonstrate that a force applied to\nthe bath particles can generate a drag force of similar magnitude acting on the\nimpurities, realizing a novel, nonperturbative Coulomb drag effect. To prove\nthis, we calculate the fully self-consistent, frequency-dependent\ntransconductivity at zero temperature in the Baym-Kadanoff conserving\napproximation. We apply our theory to excitons and exciton polaritons\ninteracting with a bath of charge carriers in a doped semiconductor embedded in\na microcavity. In external electric and magnetic fields, the drag effect\nenables electrical control of excitons and may pave the way for the\nimplementation of gauge fields for excitons and polaritons. Moreover, a\nreciprocal effect may facilitate optical manipulation of electron transport.\nOur findings establish transport measurements as a novel, powerful tool for\nprobing the many-body physics of mobile quantum impurities."
    },
    {
        "anchor": "Carrier heating and high-order harmonics generation in doped graphene by\n  a strong ac electric field: The nonlinear response of electrons (holes) in doped graphene on ac pumping\nis considered theoretically for the frequency region above the energy\nrelaxation rate but below the momentum and carrier-carrier scattering rates.\nTemporally-dependent heating of electrons by a strong ac field, which is\ndescribed within the energy balance approach, leads to an effective generation\nof high-order harmonics. The efficiency of up-conversion of the 1 mm radiation\ninto the third harmonic by a single-layer graphene is about 10^{-7} at pumping\nlevel ~100 kW/cm^2, room temperature, and concentration ~5 x 10^{11} cm^{-2}.",
        "positive": "Fermi arc reconstruction in synthetic photonic lattice: The chiral surface states of Weyl semimetals have an open Fermi surface\ncalled Fermi arc. At the interface between two Weyl semimetals, these Fermi\narcs are predicted to hybridize and alter their connectivity. In this letter,\nwe numerically study a one-dimensional (1D) dielectric trilayer grating where\nthe relative displacements between adjacent layers play the role of two\nsynthetic momenta. The lattice emulates 3D crystals without time-reversal\nsymmetry, including Weyl semimetal, nodal line semimetal, and Chern insulator.\nBesides showing the phase transition between Weyl semimetal and Chern insulator\nat telecom wavelength, this system allows us to observe the Fermi arc\nreconstruction between two Weyl semimetals, confirming the theoretical\npredictions."
    },
    {
        "anchor": "Ultrathin GaN Nanowires: Electronic, Thermal, and Thermoelectric\n  Properties: We present a comprehensive computational study of the electronic, thermal,\nand thermoelectric (TE) properties of gallium nitride nanowires (NWs) over a\nwide range of thicknesses (3--9 nm), doping densities ($10^{18}$--$10^{20}$\ncm$^{-3}$), and temperatures (300--1000 K). We calculate the low-field electron\nmobility based on ensemble Monte Carlo transport simulation coupled with a\nself-consistent solution of the Poisson and Schr\\\"odinger equations. We use the\nrelaxation-time approximation and a Poisson-Schro\\\"dinger solver to calculate\nthe electron Seebeck coefficient and thermal conductivity. Lattice thermal\nconductivity is calculated using a phonon ensemble Monte Carlo simulation, with\na real-space rough surface described by a Gaussian autocorrelation function.\nThroughout the temperature range, the Seebeck coefficient increases while the\nlattice thermal conductivity decreases with decreasing wire cross section, both\nboding well for TE applications of thin GaN NWs. However, at room temperature\nthese benefits are eventually overcome by the detrimental effect of surface\nroughness scattering on the electron mobility in very thin NWs. The highest\nroom-temperature $ZT$ of 0.2 is achieved for 4-nm-thick NWs, while further\ndownscaling degrades it. In contrast, at 1000 K, the electron mobility varies\nweakly with the NW thickness owing to the dominance of polar optical phonon\nscattering and multiple subbands contributing to transport, so $ZT$ increases\nwith increasing confinement, reaching 0.8 for optimally doped 3-nm-thick NWs.\nThe $ZT$ of GaN NWs increases with increasing temperature beyond 1000 K, which\nfurther emphasizes their suitability for high-temperature TE applications.",
        "positive": "Equilibrium angular momentum and edge current in Bose-condensed cold\n  atom systems with k-space Berry curvature: In this paper we study the properties of cold bosons in a two-dimensional\noptical lattice system where Bose-condensation occurs at a momentum point k\nwith non-zero k-space Berry curvature. By combining results from both analytic\nand numerical approaches, we show that the boson system carries non-universal,\ntemperature dependent equilibrium angular momentum and edge current at low\ntemperatures."
    },
    {
        "anchor": "Inverse Magnetoresistance of Molecular Junctions: We present calculations of spin-dependent electron transport through single\norganic molecules bridging pairs of iron nanocontacts. We predict the\nmagnetoresistance of these systems to switch from positive to negative with\nincreasing applied bias for both conducting and insulating molecules. This\nnovel inverse magnetoresistance phenomenon is robust, does not depend on the\npresence of impurities, and is unique to molecular and atomic nanoscale\nmagnetic junctions. Its physical origin is identified and its relevance to\nexperiment and to potential technological applications is discussed.",
        "positive": "Aluminum arsenide cleaved-edge overgrown quantum wires: We report conductance measurements in quantum wires made of aluminum\narsenide, a heavy-mass, multi-valley one-dimensional (1D) system. Zero-bias\nconductance steps are observed as the electron density in the wire is lowered,\nwith additional steps observable upon applying a finite dc bias. We attribute\nthese steps to depopulation of successive 1D subbands. The quantum conductance\nis substantially reduced with respect to the anticipated value for a spin- and\nvalley-degenerate 1D system. This reduction is consistent with\ndisorder-induced, intra-wire backscattering which suppresses the transmission\nof 1D modes. Calculations are presented to demonstrate the role of strain in\nthe 1D states of this cleaved-edge structure."
    },
    {
        "anchor": "Magnetic edge states of impenetrable stripe: The electron motion in a strong perpendicular magnetic field close to the\nimpenetrable stripe is considered by making use of the singular integral\nequation technique. The energy spectrum is calculated and compared with the\nenergy spectrum of the round antidot.",
        "positive": "Spin-orbit coupling and optical spin Hall effect in photonic graphene: We study the spin-orbit coupling induced by the splitting between TE and TM\noptical modes in a photonic honeycomb lattice. Using a tight-binding approach,\nwe calculate analytically the band structure. Close to the Dirac point,we\nderive an effective Hamiltonian. We find that the local reduced symmetry\n($\\mathrm{D_{3h}}$) transforms the TE-TM effective magnetic field into an\nemergent field with a Dresselhaus symmetry. As a result, particles become\nmassive, but no gap opens. The emergent field symmetry is revealed by the\noptical spin Hall effect."
    },
    {
        "anchor": "The Berry phase of dislocations in graphene and valley conserving\n  decoherence: We demonstrate that dislocations in the graphene lattice give rise to\nelectron Berry phases equivalent to quantized values {0,1/3,-1/3} in units of\nthe flux quantum, but with an opposite sign for the two valleys. An elementary\nscale consideration of a graphene Aharonov-Bohm ring equipped with valley\nfilters on both terminals, encircling a dislocation, says that in the regime\nwhere the intervalley mean free path is large compared to the intravalley phase\ncoherence length, such that the valley quantum numbers can be regarded as\nconserved on the relevant scale, the coherent valley-polarized currents\nsensitive to the topological phases have to traverse the device many times\nbefore both valleys contribute, and this is not possible at intermediate\ntemperatures where the latter length becomes of order of the device size, thus\nleading to an apparent violation of the basic law of linear transport that\nmagnetoconductance is even in the applied flux. We discuss this discrepancy in\nthe Feynman path picture of dephasing, when addressing the transition from\nquantum to classical dissipative transport. We also investigate this device in\nthe scattering matrix formalism, accounting for the effects of decoherence by\nthe Buttiker dephasing voltage probe type model which conserves the valleys,\nwhere the magnetoconductance remains even in the flux, also when different\ndecoherence times are allowed for the individual, time reversal connected,\nvalleys.",
        "positive": "Excitonic Effects on Optical Absorption Spectra of Doped Graphene: We have performed first-principles calculations to study optical absorption\nspectra of doped graphene with many-electron effects included. Both self-energy\ncorrections and electron-hole interactions are reduced due to the enhanced\nscreening in doped graphene. However, self-energy corrections and excitonic\neffects nearly cancel each other, making the prominent optical absorption peak\nfixed around 4.5 eV under different doping conditions. On the other hand, an\nunexpected increase of the optical absorbance is observed within the infrared\nand visible-light frequency regime (1 ~ 3 eV). Our analysis shows that a\ncombining effect from the band filling and electron-hole interactions results\nin such an enhanced excitonic effect on the optical absorption. These unique\nvariations of the optical absorption of doped graphene are of importance to\nunderstand relevant experiments and design optoelectronic applications."
    },
    {
        "anchor": "Giant optical activity and Kerr effect in type-I and type-II Weyl\n  semimetals: We explore optical activity in thin films and bulk of type-I and type II Weyl\nsemimetals (WSM), and demonstrate the existence of a giant Kerr effect in both.\nIn time-reversal symmetry broken WSM thin films, the polarization rotation is\ncaused by the optical Hall conductivity including the anomalous Hall term. The\nKerr angle is found to be $\\propto Q/\\omega$, with $Q$ and $\\omega$ being the\nWeyl node separation and the optical frequency, respectively. In contrast, the\noptical activity in the bulk WSM is dominated by axion electrodynamics, which\npersists even in the Pauli blocked regime of no optical transitions. In bulk\nWSM, $Q$ acts analogous to the magnetization in magnetic materials, leading to\nlarge `polar Kerr effect' (linear in $Q$) when light is incident on WSM surface\nwithout Fermi arc states, and the `Voigt effect' (quadratic in $Q$), when light\nis incident on surface with Fermi arc states.",
        "positive": "Vanishing skyrmion Hall effect at the angular momentum compensation\n  temperature of a ferrimagnet: Charged particles exhibit the Hall effect in the presence of magnetic fields.\nAnalogously, ferromagnetic skyrmions with non-zero topological charges and\nfinite fictitious magnetic fields exhibit the skyrmion Hall effect, which is\ndetrimental for applications. The skyrmion Hall effect has been theoretically\npredicted to vanish for antiferromagnetic skyrmions because the fictitious\nmagnetic field, proportional to net spin density, is zero. We experimentally\nconfirm this prediction by observing current-driven transverse elongation of\npinned ferrimagnetic bubbles. Remarkably, the skyrmion Hall effect, estimated\nwith the angle between the current and bubble elongation directions, vanishes\nat the angular momentum compensation temperature where the net spin density\nvanishes. This study establishes a direct connection between the fictitious\nmagnetic field and spin density, offering a pathway towards the realization of\nskyrmionic devices."
    },
    {
        "anchor": "Characterizing disordered fermion systems using the momentum-space\n  entanglement spectrum: The use of quantum entanglement to study condensed matter systems has been\nflourishing in critical systems and topological phases. Additionally, using\nreal-space entanglement entropies and entanglement spectra one can characterize\nlocalized and delocalized phases of disordered fermion systems. Here we instead\npropose the momentum-space entanglement spectrum as a means of characterizing\ndisordered models. We show that localization in 1D arises from the momentum\nspace entanglement between left and right movers and illustrate our methods\nusing explicit models with spatially correlated disorder that exhibit phases\nwhich avoid complete Anderson localization. The momentum space entanglement\nspectrum clearly reveals the location of delocalized states in the energy\nspectrum and can be used as a signature of the phase transition between a\ndelocalized and localized phase.",
        "positive": "Current-controlled light scattering and asymmetric plasmon propagation\n  in graphene: We demonstrate that plasmons in graphene can be manipulated using a DC\ncurrent. A source-drain current lifts the forward/backward degeneracy of the\nplasmons, creating two modes with different propagation properties parallel and\nantiparallel to the current. We show that the propagation length of the plasmon\npropagating parallel to the drift current is enhanced, while the propagation\nlength for the antiparallel plasmon is suppressed. We also investigate the\nscattering of light off graphene due to the plasmons in a periodic dielectric\nenvironment and we find that the plasmon resonance separates in two peaks\ncorresponding to the forward and backward plasmon modes. The narrower linewidth\nof the forward propagating plasmon may be of interest for refractive index\nsensing and the DC current control could be used for the modulation of\nmid-infrared electromagnetic radiation."
    },
    {
        "anchor": "Study of BC$_{14}$N-bilayer graphene: Effects of atomic spacing and\n  interatomic interaction between B and N atoms: We study the effects of an attractive interaction between the boron (B) and\nthe nitrogen (N) atoms doped in a bilayer graphene (BLG), BC$_{14}$N, on the\nelectronic, the thermal and the optical properties for two different types of a\ndoping process: First, both the B and the N atoms are doped in the same layer\nwhile the other layer is undoped. Second, the B and N atoms are doped in both\nlayers. An attractive interaction between the B and N atoms does not influence\nthe interlayer interaction in the first case, while it does in the second case.\nWe find that the strong B-N attractive interaction in one layer induces\nmetallic behavior due to the crossing of the valence band and the Fermi energy,\nwhile the strong attractive interaction between both layers induces a\nsemiconductor property arising from the emergence a bandgap. We therefore\nconfirm that the metallic-like BLG is not a good material for thermal devices\nbecause it has a low figure of merit, while we notice that the\nsemiconductor-like BLG has a high Seebeck coefficient and figure of merit as\nwell as a low thermal conductivity. The strong attractive interaction of the\nB-N atoms between the layers gives rise to a prominent peak to appear in\ndielectric function, the excitation and the absorption spectra in the low\nenergy, visible range, while a very weak peak is seen in the case of a strong\nattractive interaction between the B and N doped in one layer. Controlling the\nB and N atomic configurations in the BLG may help to improve the material for\nuse in both thermoelectric and optoelectronic devices.",
        "positive": "Visualizing Topology of Real-Energy Gapless Phase Arising from\n  Exceptional Point: The discovery of novel topological phase advances our knowledge of nature and\nstimulates the development of applications. In non-Hermitian topological\nsystems, the topology of band touching exceptional points is very important.\nHere we propose a real-energy topological gapless phase arising from\nexceptional points in one dimension, which has identical topological invariants\nas the topological gapless phase arising from degeneracy points. We develop a\ngraphic approach to characterize the topological phases, where the eigenstates\nof energy bands are mapped to the graphs on a torus. The topologies of\ndifferent phases are visualized and distinguishable; and the topological\ngapless edge state with amplification appropriate for topological lasing exists\nin the nontrivial phase. These results are elucidated through a non-Hermitian\nSu-Schrieffer-Heeger ladder. Our findings open new way for identifying topology\nphase of matter from visualizing the eigenstates."
    },
    {
        "anchor": "Amplification phenomena of Casimir force fluctuations on close\n  scatterers coupled via a coherent fermionic fluid: We study the mechanical actions affecting close scatterers immersed in a\ncoherent fermionic fluid. Using a scattering field theory, we theoretically\nanalyse the single-scatterer and the two-scatterer case. Concerning the\nsingle-scatterer case, we find that a net force affects the scatterer dynamics\nonly in non-equilibrium condition, i.e. imposing the presence of a\nnon-vanishing particle current flowing through the system. The force\nfluctuation (variance) is instead not negligible both in equilibrium and in\nnon-equilibrium conditions. Concerning the two-scatterer case, an attractive\nfluid-mediated Casimir force is experienced by the scatterers at small spatial\nseparation, while a decaying attractive/repulsive behavior as a function of the\nscatterer separation is found. Furthermore, the Casimir force fluctuations\nacting on a given scatterer in close vicinity of the other present an\noscillating behavior reaching a long distance limit comparable to the value of\nthe single-scatterer case. The relevance of these findings is discussed in\nconnection with fluctuation phenomena in low-dimensional nanostructures and\ncold atoms systems.",
        "positive": "Ultrafast mid-infrared nanoscopy of strained vanadium dioxide nanobeams: Long regarded as a model system for studying insulator-to-metal phase\ntransitions, the correlated electron material vanadium dioxide (VO$_2$) is now\nfinding novel uses in device applications. Two of its most appealing aspects\nare its accessible transition temperature ($\\sim$341 K) and its rich phase\ndiagram. Strain can be used to selectively stabilize different VO$_2$\ninsulating phases by tuning the competition between electron and lattice\ndegrees of freedom. It can even break the mesoscopic spatial symmetry of the\ntransition, leading to a quasi-periodic ordering of insulating and metallic\nnanodomains. Nanostructuring of strained VO$_2$ could potentially yield unique\ncomponents for future devices. However, the most spectacular property of VO$_2$\n- its ultrafast transition - has not yet been studied on the length scale of\nits phase heterogeneity. Here, we use ultrafast near-field microscopy in the\nmid-infrared to study individual, strained VO$_2$ nanobeams on the 10 nm scale.\nWe reveal a previously unseen correlation between the local steady-state\nswitching susceptibility and the local ultrafast response to below-threshold\nphotoexcitation. These results suggest that it may be possible to tailor the\nlocal photo-response of VO$_2$ using strain and thereby realize new types of\nultrafast nano-optical devices."
    },
    {
        "anchor": "Hofstadter states and reentrant charge order in a semiconductor moir\u00e9\n  lattice: The emergence of moir\\'e materials with flat bands provides a platform to\nsystematically investigate and precisely control correlated electronic phases.\nHere, we report local electronic compressibility measurements of a twisted\nWSe$_2$/MoSe$_2$ heterobilayer which reveal a rich phase diagram of\ninterpenetrating Hofstadter states and electron solids. We show that this\nreflects the presence of both flat and dispersive moir\\'e bands whose relative\nenergies, and therefore occupations, are tuned by density and magnetic field.\nAt low densities, competition between moir\\'e bands leads to a transition from\ncommensurate arrangements of singlets at doubly occupied sites to triplet\nconfigurations at high fields. Hofstadter states (i.e., Chern insulators) are\ngenerally favored at high densities as dispersive bands are populated, but are\nsuppressed by an intervening region of reentrant charge-ordered states in which\nholes originating from multiple bands cooperatively crystallize. Our results\nreveal the key microscopic ingredients that favor distinct correlated ground\nstates in semiconductor moir\\'e systems, and they demonstrate an emergent\nlattice model system in which both interactions and band dispersion can be\nexperimentally controlled.",
        "positive": "Quantum computing on magnetic racetracks with flying domain wall qubits: Domain walls (DWs) on magnetic racetracks are at the core of the field of\nspintronics, providing a basic element for classical information processing.\nHere, we show that mobile DWs also provide a blueprint for large-scale quantum\ncomputers. Remarkably, these DW qubits showcase exceptional versatility,\nserving not only as stationary qubits, but also performing the role of\nsolid-state flying qubits that can be shuttled in an ultrafast way. We estimate\nthat the DW qubits are long-lived because they can be operated at sweet spots\nto reduce potential noise sources. Single-qubit gates are implemented by moving\nthe DW, and two-qubit entangling gates exploit naturally emerging interactions\nbetween different DWs. These gates, sufficient for universal quantum computing,\nare fully compatible with current state-of-the-art experiments on racetrack\nmemories. Further, we discuss possible strategies for qubit readout and\ninitialization, paving the way toward future quantum computers based on mobile\ntopological textures on magnetic racetracks."
    },
    {
        "anchor": "Non-trivial topological structure of heat and momentum flux radiated by\n  magneto-optical nanoparticles: In the present Letter we investigate the heat and momentum fluxes radiated by\na hot magneto-optical nanoparticle in its surrounding under the action of an\nexternal magnetic field. We show that the flux lines circulate in a confined\nregion at nanometric distance from the particle around the axis of magnetic\nfield in a vortex-like configuration. Moreover we prove that the spatial\norientation of these vortices (clockwise or counterclockwise) is associated to\nthe contribution of optical resonances with topological charges m = +1 or m =\n-1 to the thermal emission. This work paves the way to a geometric description\nof heat and momentum transport in lattices of magneto-optical particles.\nMoreover it could have important applications in the field of energy storage as\nwell as in thermal management at nanoscale.",
        "positive": "Illustrating field emission theory by using Lauritsen plots of\n  transmission probability and barrier strength: This technical note relates to the theory of cold field electron emission\n(CFE). It starts by suggesting that, to emphasize common properties in relation\nto CFE theory, the term 'Lauritsen plot' could be used to describe all\ngraphical plots made with the reciprocal of barrier field (or the reciprocal of\na quantity proportional to barrier field) on the horizontal axis. It then\nargues that Lauritsen plots related to barrier strength (G) and transmission\nprobability (D) could play a useful role in discussion of CFE theory. Such\nplots would supplement conventional Fowler-Nordheim (FN) plots. All these plots\nwould be regarded as particular types of Lauritsen plot. The Lauritsen plots of\n-G and lnD can be used to illustrate how basic aspects of FN tunnelling theory\nare influenced by the mathematical form of the tunnelling barrier. These, in\nturn, influence local emission current density and emission current.\nIllustrative applications used in this note relate to the well-known exact\ntriangular and Schottky-Nordheim barriers, and to the Coulomb barrier (i.e.,\nthe electrostatic component of the electron potential energy barrier outside a\nmodel spherical emitter). For the Coulomb barrier, a good analytical series\napproximation has been found for the barrier-form correction factor; this can\nbe used to predict the existence (and to some extent the properties) of related\ncurvature in FN plots."
    },
    {
        "anchor": "Fundamental intrinsic lifetimes in semiconductor self-assembled quantum\n  dots: The self-assembled quantum dots (QDs) provide an ideal platform for\nrealization of quantum information technology because it provides on demand\nsingle photons, entangled photon pairs from biexciton cascade pro- cess, single\nspin qubits, and so on. The fine structure splitting (FSS) of exciton is a\nfundamental property of QDs for thees applications. From the symmetry point of\nview, since the two bright exciton states belong to two different\nrepresentations for QDs with C2v symmetry, they should not only have different\nenergies, but also have different lifetimes, which is termed exciton lifetime\nasymmetry. In contrast to extensively studied FSS, the investigation of the\nexciton lifetime asymmetry is still missed in literature. In this work, we\ncarried out the first investigation of the exciton lifetime asymmetry in\nself-assembled QDs and presented a theory to deduce lifetime asymmetry\nindirectly from measurable qualities of QDs. We further revealed that intrinsic\nlifetimes and their asymmetry are fundamental quantities of QDs, which\ndetermine the bound of the extrinsic lifetime asymmetries, polarization angles,\nFSSs, and their evolution under uniaxial external forces. Our findings provide\nan important basis to deeply understanding properties of QDs.",
        "positive": "Stabilizing nuclear spins around semiconductor electrons via the\n  interplay of optical coherent population trapping and dynamic nuclear\n  polarization: We experimentally demonstrate how coherent population trapping (CPT) for\ndonor-bound electron spins in GaAs results in autonomous feedback that prepares\nstabilized states for the spin polarization of nuclei around the electrons. CPT\nwas realized by excitation with two lasers to a bound-exciton state.\nTransmission studies of the spectral CPT feature on an ensemble of electrons\ndirectly reveal the statistical distribution of prepared nuclear spin states.\nTuning the laser driving from blue to red detuned drives a transition from one\nto two stable states. Our results have importance for ongoing research on\nschemes for dynamic nuclear spin polarization, the central spin problem and\ncontrol of spin coherence."
    },
    {
        "anchor": "Quantum Corrections to Thermopower and Conductivity in Graphene: The quantum corrections to the conductivity and the thermopower in monolayer\ngraphene are studied. We use the recursive Green's function method to calculate\nnumerically the conductivity and the thermopower of graphene. We then analyze\nthese weak localization corrections by fitting with the analytical theory as\nfunction of the impurity parameters and the gate potential. As a result of the\nquantum corrections to the thermopower, we find large magnetothermopower which\nis shown to provide a very sensitive measure of the size and strength of the\nimpurities. We compare these analytical and numerical results with existing\nexperimental measurements of magnetoconductance of single layer graphene and\nfind that the average size and strength of the impurities in these samples can\nthereby be determined. We suggest favorable parameter ranges for future\nmeasurements of the magnetothermopower.",
        "positive": "Engineering Quantum Confinement in Semiconducting van der Waals\n  Heterostructure: Spatial confinement and manipulation of charged carriers in semiconducting\nnanostructures are essential for realizing quantum electronic devices.\nGate-defined nanostructures made of two-dimensional (2D) semiconducting\ntransition metal dichalcogenides (TMDCs) have the potential to add a unique\nadditional control of quantum degrees of freedom owing to valley-spin locking\nof confined carriers near the band edges. However, due to prevailing\ninhomogeneities in the conducting channels, it has been difficult to realize\nquantum confinement in 2D TMDCs with well-controlled tunnel-coupling strength.\nHere we demonstrate quantum transport in lateral gate-defined 2D electron\nquantum dots formed in atomically thin TMDC heterostructures. Utilizing\nmicro-fabricated local contact gates, encapsulation in 2D dielectrics and light\nillumination at low temperatures, we show that the quality of TMDC 2D electron\ngases (2DEGs) can be improved, rendering them suitable for mesoscopic quantum\ntransport measurements. We observe quantized conductance in quantum point\ncontact (QPC) channels controlled by gate-tunable confinement. We also\ndemonstrate single electron transport in TMDC quantum dots (QD) with tunable\ntunnel-coupling. Our observation holds promise for the quantum manipulation of\nspin and valley degrees of freedom in engineered TMDC nanostructures, enabling\nversatile 2D quantum electronic devices."
    },
    {
        "anchor": "Spectroscopy of Equilibrium and Non-Equilibrium Charge Transfer in\n  Semiconductor Quantum Structures: We investigate equilibrium and non-equilibrium charge-transfer processes by\nperforming high-resolution transport spectroscopy. Using electrostatically\ndefined quantum dots for energy-selective emission and detection, we achieved\nunprecedented spectral resolution and a high degree of tunability of relevant\nexperimental parameters. Most importantly, we observe that the spectral width\nof elastically transferred electrons can be substantially smaller than the\nlinewidth of a thermally broadened Coulomb peak. This finding indicates that\nthe charge-transfer process is fast compared to the electron--phonon\ninteraction time. By drawing an analogy to double quantum dots, we argue that\nthe spectral width of the elastic resonance is determined by the lifetime\nbroadening $h\\it{\\Gamma}$ of the emitter and detector states. Good agreement\nwith the model is found also in an experiment in which the charge transfer is\nin the regime $h\\it{\\Gamma}\\gg k_{\\rm{B}}T$. By performing spectroscopy below\nthe Fermi energy, we furthermore observe elastic and inelastic transfer of\nholes.",
        "positive": "Nanometer-scale Exchange Interactions Between Spin Centers in Diamond: Exchange interactions between isolated pairs of spin centers in diamond have\nbeen calculated, based on an accurate atomistic electronic structure for\ndiamond and any impurity atoms, for spin-center separations up to 2~nm. The\nexchange interactions exceed dipolar interactions for spin center separations\nless than 3~nm. NV$^-$ spin centers, which are extended defects, interact very\ndifferently depending on the relative orientations of the symmetry axis of the\nspin center and the radius vector connecting the pair. Exchange interactions\nbetween transition-metal dopants behave similarly to those of NV$^-$ centers.\nThe Mn\\---Mn exchange interaction decays with a much longer length scale than\nthe Cr\\---Cr and Ni\\---Ni exchange interactions, exceeding dipolar interactions\nfor Mn\\---Mn separations less than 5~nm. Calculations of these highly\nanisotropic and spin-center-dependent interactions provide the potential for\ndesign of the spin-spin interactions for novel nanomagnetic structures."
    },
    {
        "anchor": "Emergence of Neutral Modes in Laughlin-like Fractional Quantum Hall\n  Phases: Chiral gapless boundary modes are characteristic of quantum Hall (QH) states.\nFor hole-conjugate fractional QH phases counterpropagating edge modes (upstream\nand downstream) are expected. In the presence of electrostatic interactions and\ndisorder these modes may renormalize into charge and upstream neutral modes.\nOrthodox models of Laughlin phases anticipate only a downstream charge mode.\nHere we show that in the latter case, in the presence of a smooth confining\npotential, edge reconstruction leads to the emergence of pairs of\ncounterpropagating modes, which, by way of mode renormalization, may give rise\nto nontopological upstream neutral modes, possessing nontrivial statistics.\nThis may explain the experimental observation of ubiquitous neutral modes, and\nthe overwhelming suppression of anyonic interference in Mach-Zehnder\ninterferometry platforms. We also point out other signatures of such edge\nreconstruction.",
        "positive": "Current Switch by Coherent Trapping of Electrons in Quantum Dots: We propose a new transport mechanism through tunnel-coupled quantum dots\nbased on the coherent population trapping effect. Coupling to an excited level\nby the coherent radiation of two microwaves can lead to an extremely narrow\ncurrent antiresonance. The effect can be used to determine interdot dephasing\nrates and is a mechanism for a very sensitive, optically controlled current\nswitch."
    },
    {
        "anchor": "Spin splitting of surface states in HgTe quantum wells: We report on beating appearance in Shubnikov-de Haas oscillations in\nconduction band of 18-22nm HgTe quantum wells under applied top-gate voltage.\nAnalysis of the beatings reveals two electron concentrations at the Fermi level\narising due to Rashba-like spin splitting of the first conduction subband H1.\nThe difference dN_s in two concentrations as a function of the gate voltage is\nqualitatively explained by a proposed toy electrostatic model involving the\nsurface states localized at quantum well interfaces. Experimental values of\ndN_s are also in a good quantitative agreement with self-consistent\ncalculations of Poisson and Schrodinger equations with eight-band kp\nHamiltonian. Our results clearly demonstrate that the large spin splitting of\nthe first conduction subband is caused by surface nature of $H1$ states\nhybridized with the heavy-hole band.",
        "positive": "Compact Model of Nanowire Tunneling FETs Including Phonon-Assisted\n  Tunneling and Quantum Capacitance: A physics-based compact model for silicon gate-all-around (GAA) nanowire\ntunneling FETs (NW-tFETs) with good accuracy has been developed by considering\nPhonon-Assisted Tunneling (PAT) and transition from Quantum Capacitance Limit\n(QCL) to Classical Limit (CL) during the device-size scaling. The impact of PAT\nresults in the broadening of a single electron-energy level to an energy band\nwith density-of-states (DOS) distribution of Lorentzian shape. As a\nconsequence, the tunneling probability at the edge of tunneling window no\nlonger changes abruptly from zero to having a finite value. By adjusting the\nparameters in the Lorentzian function, an accurate fitting to the measured\ntransfer characteristics in the subthreshold region is made possible. Besides,\nwith an analytical formula to calculate the channel potential, the model is\nable to cover naturally the transition from QCL to CL regime when the device\nsize is scaled. Furthermore, on-voltage is defined to facilitate the modeling\nand fitting processes. Comparisons with the experimental data demonstrate the\nmodel accuracy across all device operation regions and the flexibility in model\nparameter extraction is also shown."
    },
    {
        "anchor": "Photoluminescence spectroscopy of trions in quantum dots: a theoretical\n  description: We present a full configuration interaction study of the spontaneous\nrecombination of neutral and singly charged excitons (trions) in semiconductor\nquantum dots, from weak to strong coupling regimes. We find that the\nenhancement of the recombination rate of neutral excitons with increasing dot\nsize is suppressed for negative trions, and even reversed for positive trions.\nOur findings agree with recent comprehensive photoluminescence experiments in\nself-assembled quantum dots [P. Dalgarno et al. Phys. Rev. B {\\bf 77}, 245311\n(2008)] and confirm the major role played by correlations in the valence\nband.The effect of the temperature on the photoluminescence spectrum and that\nof the ratio between the electron and hole wavefunction lengthscales are also\ndescribed.",
        "positive": "Dynamical symmetry breaking in vibration-assisted transport through\n  nanostructures: A theoretical model of a single molecule coupled to many vibronic modes is\npresented. At low energies, transport is dominated by electron-vibron processes\nwhere transfer of an electron through the dot is accompanied by the\nexcitation/emission of quanta (vibrons). Because the frequency of the $n$th\nmode is taken as an $n$th multiple of the frequency of the fundamental mode,\nseveral energetically degenerate or quasi-degenerate vibronic configurations\ncan contribute to transport. We investigate the consequences of strong\nelectron-vibron coupling in a fully \\emph{symmetric} set-up. Several striking\nfeatures are predicted. In particular, a gate-asymmetry and pronounced negative\ndifferential conductance features are observed. We attribute these features to\nthe presence of slow channels originating from the interplay of Franck-Condon\nsuppression of transport channels and spin/orbital degeneracies."
    },
    {
        "anchor": "Mirror anomaly and anomalous Hall effect in type-I Dirac semimetals: In addition to the well known chiral anomaly, Dirac semimetals have been\nargued to exhibit mirror anomaly, close analogue to the parity anomaly of\n($2+1$)-dimensional massive Dirac fermions. The observable response of such\nanomaly is manifested in a singular step-like anomalous Hall response across\nthe mirror-symmetric plane in the presence of a magnetic field. Although this\nresult seems to be valid in type-II Dirac semimetals (strictly speaking, in the\nlinearized theory), we find that type-I Dirac semimetals do not possess such an\nanomaly in anomalous Hall response even at the level of the linearized theory.\nIn particular, we show that the anomalous Hall response continuously approaches\nzero as one approaches the mirror symmetric angle in a type-I Dirac semimetal\nas opposed to the singular Hall response in a type-II Dirac semimetal.\nMoreover, we show that, under certain condition, the anomalous Hall response\nmay vanish in a linearized type-I Dirac semimetal, even in the presence of time\nreversal symmetry breaking.",
        "positive": "Quantum thermodynamics of a charged magneto-oscillator coupled to a heat\n  bath: Explicit results for various quantum thermodynamic function (QTF) of a\ncharged magneto-oscillator coupled to a heat bath at arbitrary temperature are\ndemonstrated in this paper. Discernible expressions for different QTF in the\ntwo limits of very low and very high temperatures are presented for three\npopular heat bath models : Ohmic, single relaxation time and blackbody\nradiation. The central result is that the effect of magnetic field turns out to\nbe important at low temperatures yet crucial at high temperatures. It is\nobserved that the dissipation parameter, $\\gamma$, and the cyclotron frequency,\n$\\omega_c$, affect the decaying or rising behaviour of various QTF in just the\nopposite way to each other at low temperatures. In the high temperature regime,\nthe effect of $\\gamma$ is much pronounced than that of $\\omega_c$."
    },
    {
        "anchor": "Hexagonal Nanopits with the Zigzag Edge State on Graphite Surfaces\n  Synthesized by Hydrogen-Plasma Etching: We studied, by scanning tunneling microscopy, the morphology of nanopits of\nmonolayer depth created at graphite surfaces by hydrogen plasma etching under\nvarious conditions such as H$_2$ pressure, temperature, etching time, and RF\npower of the plasma generation. In addition to the known pressure-induced\ntransition of the nanopit morphology, we found a sharp temperature-induced\ntransition from many small rather round nanopits of ~150 nm size to few large\nhexagonal ones of 300-600 nm within a narrow temperature range. The remote and\ndirect plasma modes switching mechanism, which was proposed to explain the\npressure-induced transition, is not directly applicable to this newly found\ntransition. Scanning tunneling spectroscopy (STS) measurements of edges of the\nhexagonal nanopits fabricated at graphite surfaces by this method show clear\nsignatures of the peculiar electronic state localized at the zigzag edge (edge\nstate), i.e., a prominent peak near the Fermi energy accompanied by\nsuppressions on either side in the local density of states. These observations\nindicate that the hexagonal nanopits consist of a high density of zigzag edges.\nThe STS data also revealed a domain structure of the edge state in which the\nelectronic state varies over a length scale of ~3 nm along the edge. The\npresent study will pave the way for microscopic understanding of the\nanisotropic etching mechanism and of spin polarization in zigzag nanoribbons\nwhich are promising key elements for future graphene nanoelectronics.",
        "positive": "Topological Circular Dichroism in Chiral Multifold Semimetals: Uncovering the physical contents of the nontrivial topology of quantum states\nis a critical problem in condensed matter physics. Here, we study the\ntopological circular dichroism in chiral semimetals using linear response\ntheory and first-principles calculations. We show that, when the low-energy\nspectrum respects emergent SO(3) rotational symmetry, topological circular\ndichroism is forbidden for Weyl fermions, and thus is unique to chiral\nmultifold fermions. This is a result of the selection rule that is imposed by\nthe emergent symmetry under the combination of particle-hole conjugation and\nspatial inversion. Using first-principles calculations, we predict that\ntopological circular dichroism occurs in CoSi for photon energy below about 0.2\neV. Our work demonstrates the existence of a response property of\nunconventional fermions that is fundamentally different from the response of\nDirac and Weyl fermions, motivating further study to uncover other unique\nresponses."
    },
    {
        "anchor": "To the problem of electron-hole bound state in transition-metal\n  dichalcogenides: The interacting electron and hole in transition-metal dichalcogenides is\nconsidered. For investigation of the interaction between electron and hole we\nobtain the Bethe-Salpeter equation for two interacting Dirac particles. The\ndependence of a few lowest binding energies of electron and hole on the\ninteraction constant for different potentials is found. We demonstrate that the\nbehavior of the potential at small distances significantly affects on the\nvalues of the binding energies. For small interaction constant we have\ndeveloped the perturbative method of the binding energy calculation. For the\nlargre interaction constant the binding energies are found numerically. The\ncritical values of the interaction constant for the Coulomb potential and\nexponential potential are found.",
        "positive": "Engineering of robust topological quantum phases in graphene nanoribbons: Here we present a flexible strategy to realize robust nanomaterials\nexhibiting valence electronic structures whose fundamental physics is described\nby the SSH-Hamiltonian. These solid-state materials are realized using\natomically precise graphene nanoribbons (GNR). We demonstrate the controlled\nperiodic coupling of topological boundary states at junctions of armchair GNRs\nof different widths to create quasi-1D trivial and non-trivial electronic\nquantum phases. Their topological class is experimentally determined by drawing\nupon the bulk-boundary correspondence and measuring the presence (non-trivial)\nor absence (trivial) of localized end states by scanning tunneling spectroscopy\n(STS). The strategy we propose has the potential to tune the band width of the\ntopological electronic bands close to the energy scale of proximity induced\nspin-orbit coupling or superconductivity, and may allow the realization of\nKitaev like Hamiltonians and Majorana type end states."
    },
    {
        "anchor": "Hard superconducting gap in germanium: The co-integration of spin, superconducting, and topological systems is\nemerging as an exciting pathway for scalable and high-fidelity quantum\ninformation technology. High-mobility planar germanium is a front-runner\nsemiconductor for building quantum processors with spin-qubits, but progress\nwith hybrid superconductor-semiconductor devices is hindered because obtaining\na superconducting gap free of subgap states (hard gap) has proven difficult.\nHere we solve this challenge by developing a low-disorder, oxide-free interface\nbetween high-mobility planar germanium and a germanosilicide parent\nsuperconductor. This superconducting contact is formed by the\nthermally-activated solid phase reaction between a metal (Pt) and the\nsemiconductor heterostructure (Ge/SiGe). Electrical characterization reveals\nnear-unity transparency in Josephson junctions and, importantly, a hard induced\nsuperconducting gap in quantum point contacts. Furthermore, we demonstrate\nphase control of a Josephson junction and study transport in a gated\ntwo-dimensional superconductor-semiconductor array towards scalable\narchitectures. These results expand the quantum technology toolbox in germanium\nand provide new avenues for exploring monolithic superconductor-semiconductor\nquantum circuits towards scalable quantum information processing.",
        "positive": "Graphene bubbles on a substrate : Universal shape and van der Waals\n  pressure: Trapped substances between a 2D crystal, such as graphene, and an atomically\nflat substrate, for example, hexagonal boron nitride, give rise to the\nformation of bubbles. We show that the size, shape and internal pressure inside\nthese bubbles are determined by the competition between van der Waals\nattraction of a 2D crystal to the substrate and the elastic energy needed to\ndeform the atomically thin layer. This presents opportunities to use bubbles to\nstudy the elasticity of 2D materials as well as the conditions of confinement,\nyet none of these have been explored so far, either theoretically or\nexperimentally. We have created a variety of bubbles formed by monolayers of\ngraphene, hBN and MoS2 mechanically exfoliated onto hBN, graphite and MoS2\nsubstrates. Their shapes, analyzed using atomic force microscopy, are found to\nexhibit universal scaling with well-defined aspect ratios, in agreement with\ntheoretical analysis based on general properties of membranes. We also measured\nthe pressure induced by the confinement, which increased with decreasing\nbubble's size and reached tens on MPa inside submicron bubbles. This agrees\nwith our theory estimates and suggests that for bubbles with radii < 10 nm\nhydrostatic pressures can reach close to 1 GPa, which may modify the properties\nof a trapped material."
    },
    {
        "anchor": "Resonant Photonic Quasicrystalline and Aperiodic Structures: We have theoretically studied propagation of exciton-polaritons in\ndeterministic aperiodic multiple-quantum-well structures, particularly, in the\nFibonacci and Thue-Morse chains. The attention is concentrated on the\nstructures tuned to the resonant Bragg condition with two-dimensional\nquantum-well exciton. The superradiant or photonic-quasicrystal regimes are\nrealized in these structures depending on the number of the wells. The\ndeveloped theory based on the two-wave approximation allows one to describe\nanalytically the exact transfer-matrix computations for transmittance and\nreflectance spectra in the whole frequency range except for a narrow region\nnear the exciton resonance. In this region the optical spectra and the\nexciton-polariton dispersion demonstrate scaling invariance and self-similarity\nwhich can be interpreted in terms of the ``band-edge'' cycle of the trace map,\nin the case of Fibonacci structures, and in terms of zero reflection\nfrequencies, in the case of Thue-Morse structures.",
        "positive": "Unveiling quasiparticle dynamics of topological insulators through\n  Bayesian modelling: Quasiparticle - a key concept to describe interacting particles -\ncharacterizes electron-electron interaction in metals (Fermi liquid) and\nelectron pairing in superconductors. While this concept essentially relies on\nthe simplification of hard-to-solve many-body problem into one-particle picture\nand residual effects, a difficulty in disentangling many-body effects from\nexperimental quasiparticle signature sometimes hinders unveiling intrinsic\nlow-energy dynamics, as highlighted by the fierce controversy on the origin of\nDirac-band anomaly in graphene and dispersion kink in high-temperature\nsuperconductors. Here, we propose an approach to solve this fundamental problem\n- the Bayesian modelling of quasiparticles. We have chosen a topological\ninsulator $\\mathrm{TlBi(S,Se)_2}$ as a model system to formulate an inverse\nproblem of quasiparticle spectra with semiparametric Bayesian analysis, and\nsuccessfully extracted one-particle and many-body characteristics, i.e. the\nintrinsic energy gap and unusual lifetime in Dirac-quasiparticle bands. Our\napproach is widely applicable to clarify the quasiparticle dynamics of quantum\nmaterials."
    },
    {
        "anchor": "Particle-hole symmetry broken solutions in graphene nanoribbons: a\n  multi-orbital, mean-field perspective: Mean-field theories have since long predicted edge magnetism in graphene\nnanoribbons, where the order parameter is given by the local magnetization.\nHowever, signatures of edge magnetism appears elusive in the experiments,\nsuggesting another class of solutions. We employ a self-consistent mean field\napproximation within a multi-orbital tight-binding model and obtain\nparticle-hole symmetry broken solutions, where the local filling plays the role\nof the order parameter. Unlike the magnetic edge solutions, these are\ntopologically non-trivial and show zero local magnetization. A small and a\nlarge doping regime are studied, and a free energy minimum for finite hole\ndoping is encountered, which may serve as an explanation for the absence of\nexperimental evidence for magnetic edge states in zigzag graphene nanoribbons.\nThe electronic interaction may increase the finite \\(d\\)-orbital occupation,\nwhich leads to a change of the effective Coulomb interaction of the dominant\n\\(p_z\\)-orbitals. Our findings indicate that the non-magnetic solution for\nfinite hole doping becomes energetically preferred, compared to the magnetic\nphases at half-filling, once thermal fluctuations or unintentional doping from\nthe substrate are considered. This result persists even in the presence of the\n\\(d\\)-orbitals and the Coulomb interaction therein.",
        "positive": "High-temperature Aharonov-Bohm-Casher interferometer: We study theoretically the combined effect of the spin-orbit and Zeeman\ninteractions on the tunneling electron transport through a single-channel\nquantum ring threaded by magnetic flux. We focus on the high temperature case\n(temperature is much higher than the level spacing in the ring) and demonstrate\nthat spin-interference effects are not suppressed by thermal averaging. In the\nabsence of the Zeeman coupling the high-temperature tunneling conductance of\nthe ring exhibits two types of oscillations: Aharonov-Bohm oscillations with\nmagnetic flux and Aharonov-Casher oscillations with the strength of the\nspin-orbit interaction. For weak tunneling coupling both oscillations have the\nform of sharp periodic antiresonances. In the vicinity of the antiresonances\nthe tunneling electrons acquire spin polarization, so that the ring serves as a\nspin polarizer. We also demonstrate that the Zeeman coupling leads to\nappearance of two additional peaks both in the tunneling conductance and in the\nspin polarization."
    },
    {
        "anchor": "Interaction of quantum Hall systems with waveguide elastic modes: An interaction of non-uniform plane elastic modes of the waveguide type with\nmonolayer and double-layer quantum Hall systems is considered. It is shown,\nthat unlike the case of the surface acoustic wave propagation, the restriction\non maximal values of the wave vectors for which the velocity shift can be\nobserved experimentally does not take place for the waveguide modes. In case of\nstudy of incompressible fractional quantum Hall states the effect can be used\nfor measuring a dependence of the effective magnetic length on the filling\nfactor and for observing phase transitions in double-layer system under the\ninterlayer distance variation",
        "positive": "Antiferromagnet-Based Neuromorphics Using Dynamics of Topological\n  Charges: We propose a spintronics-based hardware implementation of neuromorphic\ncomputing, specifically, the spiking neural network, using topological winding\ntextures in one-dimensional antiferromagnets. The consistency of such a network\nis emphasized in light of the conservation of topological charges, and the\nnatural spatiotemporal interconversions of magnetic winding. We discuss the\nrealization of the leaky integrate-and-fire behavior of neurons and the\nspike-timing-dependent plasticity of synapses. Our proposal opens the\npossibility for an all-spin neuromorphic platform based on antiferromagnetic\ninsulators."
    },
    {
        "anchor": "Superconducting-semiconductor quantum devices: from qubits to particle\n  detectors: Recent improvements in materials growth and fabrication techniques may\nfinally allow for superconducting semiconductors to realize their potential.\nHere we build on a recent proposal to construct superconducting devices such as\nwires, Josephson junctions, and qubits inside and out-of single crystal silicon\nor germanium. Using atomistic fabrication techniques such as STM hydrogen\nlithography, heavily-doped superconducting regions within a single crystal\ncould be constructed. We describe the characteristic parameters of basic\nsuperconducting elements---a 1D wire and a tunneling Josephson junction---and\nestimate the values for boron-doped silicon. The epitaxial, single-crystal\nnature of these devices, along with the extreme flexibility in device design\ndown to the single-atom scale, may enable lower-noise or new types of devices\nand physics. We consider applications for such super-silicon devices, showing\nthat the state-of-the-art transmon qubit and the sought-after phase-slip qubit\ncan both be realized. The latter qubit leverages the natural high kinetic\ninductance of these materials. Building on this, we explore how kinetic\ninductance based particle detectors (e.g., photon or phonon) could be realized\nwith potential application in astronomy or nanomechanics. We discuss super-semi\ndevices (such as in silicon, germanium, or diamond) which would not require\natomistic fabrication approaches and could be realized today.",
        "positive": "Permalloy-based carbon nanotube spin-valve: In this Letter we demonstrate that Permalloy (Py), a widely used Ni/Fe alloy,\nforms contacts to carbon nanotubes (CNTs) that meet the requirements for the\ninjection and detection of spin-polarized currents in carbon-based spintronic\ndevices. We establish the material quality and magnetization properties of Py\nstrips in the shape of suitable electrical contacts and find a sharp\nmagnetization switching tunable by geometry in the anisotropic\nmagnetoresistance (AMR) of a single strip at cryogenic temperatures. In\naddition, we show that Py contacts couple strongly to CNTs, comparable to Pd\ncontacts, thereby forming CNT quantum dots at low temperatures. These results\nform the basis for a Py-based CNT spin-valve exhibiting very sharp resistance\nswitchings in the tunneling magnetoresistance, which directly correspond to the\nmagnetization reversals in the individual contacts observed in AMR experiments."
    },
    {
        "anchor": "Bulk and Edge excitations in a $\u03bd=1$ quantum Hall ferromagnet: In this article, we shall focus on the collective dynamics of the fermions in\na $\\nu = 1$ quantum Hall droplet. Specifically, we propose to look at the\nquantum Hall ferromagnet. In this system, the electron spins are ordered in the\nground state due to the exchange part of the Coulomb interaction and the Pauli\nexclusion principle. The low energy excitations are ferromagnetic magnons. To\nprovide a means for describing these magnons, we shall discuss a method of\nintroducing collective coordinates in the Hilbert space of many-fermion\nsystems. These collective coordinates are bosonic in nature. They map a part of\nthe fermionic Hilbert space into a bosonic Hilbert space. Using this technique,\nwe shall interpret the magnons as bosonic collective ex citations in the\nHilbert space of the many-electron Hall system. By considering a Hall droplet\nof finite extent, we shall also obtain the effective Lagrangian governing the\nspin collective excitations at the edge of the sample.",
        "positive": "Enhancement mode double top gated MOS nanostructures with tunable\n  lateral geometry: We present measurements of silicon (Si) metal-oxide-semiconductor (MOS)\nnanostructures that are fabricated using a process that facilitates essentially\narbitrary gate geometries. Stable Coulomb blockade behavior free from the\neffects of parasitic dot formation is exhibited in several MOS quantum dots\nwith an open lateral quantum dot geometry. Decreases in mobility and increases\nin charge defect densities (i.e. interface traps and fixed oxide charge) are\nmeasured for critical process steps, and we correlate low disorder behavior\nwith a quantitative defect density. This work provides quantitative guidance\nthat has not been previously established about defect densities for which Si\nquantum dots do not exhibit parasitic dot formation. These devices make use of\na double-layer gate stack in which many regions, including the critical gate\noxide, were fabricated in a fully-qualified CMOS facility."
    },
    {
        "anchor": "Magnetic microscopy and simulation of strain-mediated control of\n  magnetization in Ni/PMN-PT nanostructures: Strain-mediated thin film multiferroics comprising\npiezoelectric/ferromagnetic heterostructures enable the electrical manipulation\nof magnetization with much greater efficiency than other methods; however, the\ninvestigation of nanostructures fabricated from these materials is limited.\nHere we characterize ferromagnetic Ni nanostructures grown on a ferroelectric\nPMN-PT substrate using scanning electron microscopy with polarization analysis\n(SEMPA) and micromagnetic simulations. The magnetization of the Ni\nnanostructures can be controlled with a combination of sample geometry and\napplied electric field, which strains the ferroelectric substrate and changes\nthe magnetization via magnetoelastic coupling. We evaluate two types of\nsimulations of ferromagnetic nanostructures on strained ferroelectric\nsubstrates: conventional micromagnetic simulations including a simple uniaxial\nstrain, and coupled micromagnetic-elastodynamic simulations. Both simulations\nqualitatively capture the response of the magnetization changes produced by the\napplied strain, with the coupled solution providing more accurate\nrepresentation.",
        "positive": "Generation of two identical photons from a quantum dot in a microcavity: We propose and characterize a two-photon emitter in a highly polarised,\nmonochromatic and directional beam, realized by means of a quantum dot embedded\nin a linearly polarized cavity. In our scheme, the cavity frequency is tuned to\nhalf the frequency of the biexciton (two excitons with opposite spins) and\nlargely detuned from the excitons thanks to the large biexciton binding energy.\nWe show how the emission can be Purcell enhanced by several orders of magnitude\ninto the two-photon channel for available experimental systems."
    },
    {
        "anchor": "Hybrid exceptional point created from type III Dirac point: Degeneracy (exceptional) points embedded in energy band are distinct by their\ntopological features. We report different hybrid two-state coalescences (EP2s)\nformed through merging two EP2s with opposite chiralities that created from the\ntype III Dirac points emerging from a flat band. The band touching hybrid EP2,\nwhich is isolated, is induced by the destructive interference at the proper\nmatch between non-Hermiticity and synthetic magnetic flux. The degeneracy\npoints and different types of exceptional points are distinguishable by their\ntopological features of global geometric phase associated with the scaling\nexponent of phase rigidity. Our findings not only pave the way of merging EPs\nbut also shed light on the future investigations of non-Hermitian topological\nphases.",
        "positive": "Phonon-assisted Exciton Dissociation in Transition Metal Dichalcogenides: Monolayers of transition metal dichalcogenides (TMDs) have been established\nin the last years as promising materials for novel optoelectronic devices.\nHowever, the performance of such devices is often limited by the dissociation\nof tightly bound excitons into free electrons and holes. While previous studies\nhave investigated tunneling at large electric fields, we focus in this work on\nphonon-assisted exciton dissociation that is expected to be the dominant\nmechanism at small fields. We present a microscopic model based on the density\nmatrix formalism providing access to time- and momentum-resolved exciton\ndynamics including phonon-assisted dissociation. We track the pathway of\nexcitons from optical excitation via thermalization to dissociation,\nidentifying the main transitions and dissociation channels. Furthermore, we\nfind intrinsic limits for the quantum efficiency and response time of a\nTMD-based photodetector and investigate their tunability with externally\naccessible knobs, such as excitation energy, substrate screening, temperature\nand strain. Our work provides microscopic insights in fundamental mechanisms\nbehind exciton dissociation and can serve as a guide for the optimization of\nTMD-based optoelectronic devices."
    },
    {
        "anchor": "Model Exact Low-Lying States and Spin Dynamics in Ferric Wheels; Fe$_6$\n  to Fe$_{12}$: Using an efficient numerical scheme that exploits spatial symmetries and\nspin-parity, we have obtained the exact low-lying eigenstates of exchange\nHamiltonians for ferric wheels up to Fe$_{12}$. The largest calculation\ninvolves the Fe$_{12}$ ring which spans a Hilbert space dimension of about 145\nmillion for M$_s$=0 subspace. Our calculated gaps from the singlet ground state\nto the excited triplet state agrees well with the experimentally measured\nvalues. Study of the static structure factor shows that the ground state is\nspontaneously dimerized for ferric wheels. Spin states of ferric wheels can be\nviewed as quantized states of a rigid rotor with the gap between the ground and\nthe first excited state defining the inverse of moment of inertia. We have\nstudied the quantum dynamics of Fe$_{10}$ as a representative of ferric wheels.\nWe use the low-lying states of Fe$_{10}$ to solve exactly the time-dependent\nSchr\\\"odinger equation and find the magnetization of the molecule in the\npresence of an alternating magnetic field at zero temperature. We observe a\nnontrivial oscillation of magnetization which is dependent on the amplitude of\nthe {\\it ac} field. We have also studied the torque response of Fe$_{12}$ as a\nfunction of magnetic field, which clearly shows spin-state crossover.",
        "positive": "Electron spin rotations induced by oscillating Rashba interaction in a\n  quantum wire: A novel method and nanodevice are introduced that allows to rotate the single\nelectron spin confined in a gated electrostatic InSb nanowire quantum dot.\nProposed method does not require application of any (oscillating or static)\nexternal magnetic fields. Our proposal instead employs spatial and time\nmodulation of confining potential induced by electric gates, which, in turn\nleads to oscillating Rashba type spin-orbit coupling. Moving electron back and\nforth in such a variable Rashba field allows for realization of spin rotations\naround two different axes separately without using an external magnetic field.\nThe results are supported by realistic three-dimensional time dependent\nPoisson-Schr\\\"{o}dinger calculations for systems and material parameters\ncorresponding to experimentally accessible structures."
    },
    {
        "anchor": "Fermi Liquid Theory Sheds Light on \"Hot\" EHL in 1L-MoS$_2$: 2D transition metal dichalcogenides (TMDCs) exhibit an electron-hole liquid\nphase transition at unusually high temperatures. Because these materials are\natomically thin, optical excitation leads to material expansion. As a result,\nduring the EHL phase transition the electronic band structure evolves due to\nboth material thermal expansion and renormalization of the bands under high\nexcitation densities. Specifically, these effects lead to indirect gap\nelectronic band structure with a valence band maximum located at the $\\Gamma$\nvalley. In this work we developed a methodology for analyzing the spectral\nevolution of the photoluminescence of suspended 1L-MoS$_2$ during the EHL phase\ntransition by using Fermi liquid theory. The resulting analysis reveals\nvalley-specific carrier densities, radiative recombination efficiencies, and\nintraband carrier relaxation kinetics in 1L-MoS$_2$. More broadly, the results\noutline a methodology for predicting critical EHL parameters, shedding light\nonto the EHL phase transition in 2D TDMCs.",
        "positive": "Yoctocalorimetry: phonon counting in nanostructures: It appears feasible with nanostructures to perform calorimetry at the level\nof individual thermal phonons. Here I outline an approach employing\nmonocrystalline mesoscopic insulators, which can now be patterned from\nsemiconductor heterostructures into complex geometries with full, three-\ndimensional relief. Successive application of these techniques also enables\ndefinition of integrated nanoscale thermal transducers; coupling these to a dc\nSQUID readout yields the requisite energy sensitivity and temporal resolution\nwith minimal back action. The prospect of phonon counting opens intriguing\nexperimental possibilities with analogies in quantum optics. These include\nfluctuation-based phonon spectroscopy, phonon shot noise in the energy\nrelaxation of nanoscale systems, and quantum statistical phenomena such as\nphonon bunching and anticorrelated electron-phonon exchange."
    },
    {
        "anchor": "What's so Hot about Electrons in Metal Nanoparticles?: Metal nanoparticles are excellent light absorbers. The absorption processes\ncreate highly excited electron-hole pairs and recently there has been interest\nin harnessing these hot charge carriers for photocatalysis and solar energy\nconversion applications. The goal of this Perspectives article is to describe\nthe dynamics and energy distribution of the charge carriers produced by photon\nabsorption, and the implications for the photocatalysis mechanism. We will also\ndiscuss how spectroscopy can be used to provide insight into the coupling\nbetween plasmons and molecular resonances. In particular, the analysis shows\nthat the choice of material and shape of the nanocrystal can play a crucial\nrole in hot electron generation and coupling between plasmons and molecular\ntransitions. The detection and even calculation of many-body hot-electron\nprocesses in the plasmonic systems with continuous spectra of electrons and\nshort lifetimes are challenging, but at the same time very interesting from the\npoint of view of both potential applications and fundamental physics. We\npropose that developing an understanding of these processes will provide a\npathway for improving the efficiency of plasmon-induced photocatalysis.",
        "positive": "Phase Diagram of Magnetization Reversal Processes in Nanorings: We investigate magnetization reversal processes of magnetic nanorings. Using\na recently developed efficient cartesian coordinates fast multipole method,\nmagnetization switching phase diagrams are constructed for such structures. We\nfind that the dominant switching mechanisms strongly depend on the relative\nspatial dimensions of the rings, i.e. height, width and radius. Furthermore,\nthey are found to depend on a characteristic exchange length scale, which is\ndetermined by the competing short-range ferromagnetic and long-range dipolar\ninteractions in these systems. Detailed simulations allow us to identify three\nnovel switching mechanisms, which should be useful for building high density\nstorage systems."
    },
    {
        "anchor": "On-chip terahertz modulation and emission with integrated graphene\n  junctions: The efficient modulation and control of ultrafast signals on-chip is of\ncentral importance in terahertz (THz) communications and a promising route\ntoward sub-diffraction limit THz spectroscopy. Two-dimensional (2D) materials\nmay provide a platform for these endeavors. We explore this potential,\nintegrating high-quality graphene p-n junctions within two types of planar\ntransmission line circuits to modulate and emit picosecond pulses. In a\ncoplanar stripline geometry, we demonstrate electrical modulation of THz signal\ntransmission by 95%. In a Goubau waveguide geometry, we achieve complete\ngate-tunable control over THz emission from a photoexcited graphene junction.\nThese studies inform the development of on-chip signal manipulation and\nhighlight prospects for 2D materials in THz applications.",
        "positive": "The drag of photons by electric current in quantum wells: The flow of electric current in quantum well breaks the space inversion\nsymmetry, which leads to the dependence of the radiation transmission on the\nrelative orientation of current and photon wave vector, this phenomenon can be\nnamed current drag of photons. We have developed a microscopic theory of such\nan effect for intersubband transitions in quantum wells taking into account\nboth depolarization and exchange-correlation effects. It is shown that the\neffect of the current drag of photons originates from the asymmetry of\nintersubband optical transitions due to the redistribution of electrons in\nmomentum space. We show that the presence of dc electric current leads to the\nshift of intersubband resonance position and affects both transmission\ncoefficient and absorbance in quantum wells."
    },
    {
        "anchor": "Anderson localization in fractional quantum Hall effect: The interplay between interaction and disorder-induced localization is of\nfundamental interest. This article addresses localization physics in the\nfractional quantum Hall state, where both interaction and disorder have\nnonperturbative consequences. We provide compelling theoretical evidence that\nthe localization of a single quasiparticle of the fractional quantum Hall state\nat filling factor $\\nu=n/(2n+1)$ has a striking {\\it quantitative}\ncorrespondence to the localization of a single electron in the $(n+1)$th Landau\nlevel. By analogy to the dramatic experimental manifestations of Anderson\nlocalization in integer quantum Hall effect, this leads to predictions in the\nfractional quantum Hall regime regarding the existence of extended states at a\ncritical energy, and the nature of the divergence of the localization length as\nthis energy is approached. Within a mean field approximation these results can\nbe extended to situations where a finite density of quasiparticles is present.",
        "positive": "Dispersionless propagation of electron wavepackets in single-walled\n  carbon nanotubes: We investigate the propagation of electron wavepackets in single-walled\ncarbon nanotubes via a Lindblad-based density-matrix approach that enables us\nto account for both dissipation and decoherence effects induced by various\nphonon modes. We show that, while in semiconducting nanotubes the wavepacket\nexperiences the typical dispersion of conventional materials, in metallic\nnanotubes its shape remains essentially unaltered, even in the presence of the\nelectron-phonon coupling, up to micron distances at room temperature."
    },
    {
        "anchor": "Quantum and Classical Magnetoresistance in Ambipolar Topological\n  Insulator Transistors with Gate-tunable Bulk and Surface Conduction: Weak antilocalization (WAL) and linear magnetoresistance (LMR) are two most\ncommonly observed magnetoresistance (MR) phenomena in topological insulators\n(TIs) and often attributed to the Dirac topological surface states (TSS).\nHowever, ambiguities exist because these phenomena could also come from bulk\nstates (often carrying significant conduction in many TIs) and are observable\neven in non-TI materials. Here, we demonstrate back-gated ambipolar TI\nfield-effect transistors in (Bi0.04Sb0.96)2Te3 thin films grown by molecular\nbeam epitaxy on SrTiO3(111), exhibiting a large carrier density tunability (by\nnearly 2 orders of magnitude) and a metal-insulator transition in the bulk\n(allowing effectively switching off the bulk conduction). Tuning the Fermi\nlevel from bulk band to TSS strongly enhances both the WAL (increasing the\nnumber of quantum coherent channels from one to peak around two) and LMR\n(increasing its slope by up to 10 times). The SS-enhanced LMR is accompanied by\na strongly nonlinear Hall effect, suggesting important roles of charge\ninhomogeneity (and a related classical LMR), although existing models of LMR\ncannot capture all aspects of our data. Our systematic gate and temperature\ndependent magnetotransport studies provide deeper insights into the nature of\nboth MR phenomena and reveal differences between bulk and TSS transport in TI\nrelated materials.",
        "positive": "Topological phase transitions induced by the variation of exchange\n  couplings in graphene: We consider a modified graphene model under exchange couplings. Various\nquantum anomalous phases are known to emerge under uniform or staggered\nexchange couplings. We introduce the twist between the orientations of two\nsublattice exchange couplings, which is useful for examining how such\ntopologically nontrivial phases under different types of exchange couplings are\nconnected to one another. The phase diagrams constructed by the variation of\nexchange coupling strengths and twist angles exhibit rich structures of\nsuccessive topological transitions. We analyze the emergence of peculiar phases\nin terms of the evolution of the energy dispersions. Perturbation schemes\napplied to the energy levels turn out to reproduce well phase boundary lines up\nto moderate values of the twist angle. We also discover two close topological\ntransitions under uniform exchange couplings, which is attributed to the\ninterplay of the trigonal-warping deformation due to Rashba spin-orbit coupling\nand the staggered sublattice potential. Finally the implications of Berry\ncurvature structure and topological excitations in real and pseudo spin\ntextures are discussed."
    },
    {
        "anchor": "Observation of linear-polarization-sensitivity in the\n  microwave-radiation-induced magnetoresistance oscillations: In the quasi two-dimensional GaAs/AlGaAs system, we investigate the effect of\nrotating \\textit{in-situ} the electric field of linearly polarized microwaves\nrelative to the current, on the microwave-radiation-induced magneto-resistance\noscillations. We find that the frequency and the phase of the photo-excited\nmagneto-resistance oscillations are insensitive to the polarization. On the\nother hand, the amplitudes of the magnetoresistance oscillations are remarkably\nresponsive to the relative orientation between the microwave antenna and the\ncurrent-axis in the specimen. The results suggest a striking\nlinear-polarization-sensitivity in the radiation-induced magnetoresistance\noscillations.",
        "positive": "Magnetotransport induced by anomalous Hall effect: In a magnetic metal, the Hall resistance is generally taken to be the sum of\nthe ordinary Hall resistance and the anomalous Hall resistance. Here it is\nshown that this empirical relation is no longer valid when either the ordinary\nHall angle or the anomalous Hall angle is not small. Using the proper\nconductivity relation, we reveal an unexpected magnetoresistance (MR) induced\nby the anomalous Hall effect (AHE). A $B$-linear MR arises and the sign of the\nslope depends on the sign of the anomalous Hall angle, giving rise to a\ncharacteristic bowtie shape. The Hall resistance in a single-band system can\nexhibit a nonlinearity which is usually considered as a characteristic of a\ntwo-band system. A $B$-symmetric component appears in the Hall. These effects\nreflect the fundamental difference between the ordinary Hall effect and the\nAHE. Furthermore, we experimentally reproduce the unusual MR and Hall reported\nbefore in Co$_3$Sn$_2$S$_2$ and show that these observations can be well\nexplained by the proposed mechanism. MR often observed in quantum anomalous\nHall insulators provides further confirmation of the picture. The effect may\nalso account for the large MR observed in non-magnetic three-dimensional\ntopological Dirac semimetals."
    },
    {
        "anchor": "Elongated element as a model of point contact in ion-conducting medium: In present work it is suggested the concept of continual multi-electrode\nsystem being realized on the elongated electrically conducting element immersed\ninto electrolyte. Conjugation of such kind of system with the point-contact\nstructure creates the unique electrode architecture and permits realizing of\nthe auto-oscillation process of electrochemical commutation at atomic scale.\nDuring this process the nanostructure is being realized in a form of point\ncontact at the place of the mutual touching of the dendrite top and\ncounter-electrode. The ability of point contacts to concentrate the electric\nfield in assemblage with the peculiar properties of elongated element causes\nunambiguously the localization of all the electrochemical transformations at\nthe dendrite top, where contact is forming.",
        "positive": "Mesoscopic Origin of Ferroelectric-Ferroelectric Transition in BaTiO3: Ferroelectric materials are the core of common technologies, such as medical\nultrasound, mobile-phone antennae and low-power memory devices. The\ntechnological interest in ferroelectrics stems from the existence of switchable\nmesoscale polarization domains. Hence, understanding the origin of\nferroelectric functionality requires realization of the domain dynamics during\na ferroelectric transformation. However, domain dynamics characterization at\nthe mesoscale is typically too slow with respect to the abrupt ferroic\ntransition. Using scanning probe microscopy with 15-mK thermal-, and\ndeep-submicron spatial-resolution, we realized the domain dynamics during an\northorhombic-to-tetragonal transition in the seminal ferroelectric BaTiO3. We\nshow that the transition comprises four distinguishable mechanisms. The\ndominant mechanism is a step-by-step progression of a tetragonal-domain\nwavefront into the orthorhombic phase. This progression is accompanied by\nripple-like surface irregularities. Small island domains that remained\northorhombic diffuse then slowly after the wavefront progression. Finally, the\nresultant tetragonal domains equilibrate by coalescing in a constant-speed.\nThese observations, which are accompanied by quantitative data, bridge between\nexisting macroscopic and microscopic models regarding the nature of\nferroelectric transitions, showing the mesoscale origin of ferroelectricity."
    },
    {
        "anchor": "Density of States and Conductivity of Granular Metal or Array of Quantum\n  Dots: The conductivity of a granular metal or an array of quantum dots usually has\nthe temperature dependence associated with variable range hopping within the\nsoft Coulomb gap of density of states. This is difficult to explain because\nneutral dots have a hard charging gap at the Fermi level. We show that\nuncontrolled or intentional doping of the insulator around dots by donors leads\nto random charging of dots and finite bare density of states at the Fermi\nlevel. Then Coulomb interactions between electrons of distant dots results in\nthe a soft Coulomb gap. We show that in a sparse array of dots the bare density\nof states oscillates as a function of concentration of donors and causes\nperiodic changes in the temperature dependence of conductivity. In a dense\narray of dots the bare density of states is totally smeared if there are\nseveral donors per dot in the insulator.",
        "positive": "Mathematical results on the chiral model of twisted bilayer graphene\n  (with an appendix by Mengxuan Yang and Zhongkai Tao): The study of twisted bilayer graphene (TBG) is a hot topic in condensed\nmatter physics with special focus on {\\em magic angles} of twisting at which\nTBG acquires unusual properties. Mathematically, topologically non-trivial flat\nbands appear at those special angles. The chiral model of TBG pioneered by\nTarnopolsky--Kruchkov--Vishwanath has particularly nice mathematical properties\nand we survey, and in some cases, clarify, recent rigorous results which\nexploit them."
    },
    {
        "anchor": "Topological flat bands in rhombohedral tetralayer and multilayer\n  graphene on hexagonal boron nitride moire superlattices: We show that rhombohedral four-layer graphene (4LG) nearly aligned with a\nhexagonal boron nitride (hBN) substrate often develops nearly flat isolated low\nenergy bands with non-zero valley Chern numbers. The bandwidths of the isolated\nflatbands are controllable through an electric field and twist angle, becoming\nas narrow as $\\sim10~$meV for interlayer potential differences between top and\nbottom layers of $|\\Delta|\\approx 10\\sim15~$meV and $\\theta \\sim 0.5^{\\circ}$\nat the graphene and boron nitride interface. The local density of states (LDOS)\nanalysis shows that the nearly flat band states are associated to the non-dimer\nlow energy sublattice sites at the top or bottom graphene layers and their\ndegree of localization in the moire superlattice is strongly gate tunable,\nexhibiting at times large delocalization despite of the narrow bandwidth. We\nverified that the first valence bands' valley Chern numbers are\n$C^{\\nu=\\pm1}_{V1} = \\pm n$, proportional to layer number for $n$LG/BN systems\nup to $n = 8$ rhombohedral multilayers.",
        "positive": "Influence of Landau levels in the phonon dispersion of Weyl semimetals: Weyl semimetals display unusual electronic transport properties when placed\nunder magnetic fields. Here, we investigate how magnetic fields alter the\ndynamics of long wavelength lattice vibrations in these materials. To that end,\nwe develop a theory for the phonon dispersion, which incorporates contributions\nfrom chiral and nonchiral Landau levels, electron-phonon interactions,\nelectron-electron interactions, and disorder. We predict (i) a\nmagnetic-field-induced hybridization between optical phonons and plasmons, (ii)\navoided crossings between pseudoscalar optical phonons and electronic\nexcitations originating from nonchiral Landau levels, (iii) a sharp dependence\nof the sound velocity on the relative angle between the sound propagation and\nthe magnetic field. We compare our results to recent theoretical studies on the\nsignatures of the chiral anomaly in phonon dynamics."
    },
    {
        "anchor": "Phase diagram of magnetic configurations for soft magnetic nanodots of\n  circular and elliptical shape obtained by micromagnetic simulation: Magnetic disks or dots of soft magnetic material of sub-micron dimensions may\nhave as the lowest energy magnetic configuration a single-domain structure,\nwith magnetization either perpendicular of parallel to the plane, or else may\nform magnetic vortices. The properties of these vortices may be used to encode\ndata bits, in magnetic memory applications. In the present work the OOMMF code\nwas used to compute by micromagnetic simulation the energy and the\nmagnetization of circular and elliptical nanodots of permalloy. For the\nelliptical magnetic dots the analysis was made for variable thickness and\nlength of major axis, keeping a 2:1 axis ratio. From the simulations, a phase\ndiagram was constructed, where the ground state configurations of the nanodots\nare represented in a diagram of nanodot height versus length of the major axis\n$2a$ of the ellipse. The phase diagram obtained includes regions with one and\ntwo vortices; it is similar, but more complex than that derived using a\nnumerical scaling approach, since it includes configurations with lateral\nvortices. These diagrams are useful as guides for the choice of dimensions of\nelliptical nanodots for practical applications.",
        "positive": "Distribution of Resonance Widths and Dynamics of Continuum Coupling: We analyze the statistics of resonance widths in a many-body Fermi system\nwith open decay channels. Depending on the strength of continuum coupling, such\na system reveals growing deviations from the standard chi-square\n(Porter-Thomas) width distribution. The deviations emerge from the process of\nincreasing interaction of intrinsic states through common decay channels; in\nthe limit of perfect coupling this process leads to the super-radiance phase\ntransition. The width distribution depends also on the intrinsic dynamics\n(chaotic vs regular). The results presented here are important for\nunderstanding the recent experimental data concerning the width distribution\nfor neutron resonances in nuclei."
    },
    {
        "anchor": "Quantum entanglement of a tunneling spin with mechanical modes of a\n  torsional resonator: We solve Schr\\\"odinger equation describing a tunneling macrospin coupled to a\ntorsional oscillator. Energy spectrum is studied for various quantum regimes.\nMagnetic susceptibility and noise spectrum are computed. We show that\nentanglement of the spin with mechanical modes of a subnanometer oscillator\nresults in the decoherence of spin tunneling. For larger oscillators the\npresence of a tunneling spin can be detected through splitting of the\nmechanical mode at the resonance. Our results apply to experiments with\nmagnetic molecules coupled to nanoresonators.",
        "positive": "Two-color spin noise spectroscopy: Using spin fluctuation correlations\n  to reveal homogeneous linewidths within quantum dot ensembles: \"Spin noise spectroscopy\" (SNS) is a powerful optical technique for probing\nelectron and hole spin dynamics that is based on detecting their intrinsic and\nrandom fluctuations while in thermal equilibrium, an approach guaranteed by the\nfluctuation-dissipation theorem. Because SNS measures fluctuation properties\nrather than conventional response functions, we show that fluctuation\n\\emph{correlations} can be exploited in multi-probe noise studies to reveal\ninformation that in general cannot be accessed by conventional linear optical\nspectroscopy, such as the underlying homogeneous linewidths of individual\nconstituents within inhomogeneously-broadened systems. This is demonstrated in\nan ensemble of singly-charged (In,Ga)As quantum dots using two weak probe\nlasers: When the two lasers have the same wavelength, they are sensitive to the\nsame QDs in the ensemble and their spin fluctuation signals are correlated. In\ncontrast, two probe lasers that are widely detuned from each other measure\ndifferent subsets of QDs, leading to uncorrelated fluctuations. Measuring the\nnoise correlation versus laser detuning directly reveals the QD homogeneous\nlinewidth even in the presence of a strong inhomogeneous broadening. Such\nnoise-based correlation techniques are not limited to semiconductor spin\nsystems, but can be widely applied to any system in which intrinsic\nfluctuations are measurable."
    },
    {
        "anchor": "Designed defects in 2D antidot lattices for quantum information\n  processing: We propose a new physical implementation of spin qubits for quantum\ninformation processing, namely defect states in antidot lattices defined in the\ntwo-dimensional electron gas at a semiconductor heterostructure. Calculations\nof the band structure of a periodic antidot lattice are presented. A point\ndefect is created by removing a single antidot, and calculations show that\nlocalized states form within the defect, with an energy structure which is\nrobust against thermal dephasing. The exchange coupling between two electrons\nresiding in two tunnel-coupled defect states is calculated numerically. We find\nresults reminiscent of double quantum dot structures, indicating that the\nsuggested structure is a feasible physical implementation of spin qubits.",
        "positive": "Kramers Nodal Line Metals: Recently, it was pointed out that all chiral crystals with spin-orbit\ncoupling (SOC) can be Kramers Weyl semimetals (KWSs) which possess Weyl points\npinned at time-reversal invariant momenta. In this work, we show that all\nachiral non-centrosymmetric materials with SOC can be a new class of\ntopological materials, which we term Kramers nodal line metals (KNLMs). In\nKNLMs, there are doubly degenerate lines, which we call Kramers nodal lines\n(KNLs), connecting time-reversal invariant momenta. The KNLs create two types\nof Fermi surfaces, namely, the spindle torus type and the octdong type.\nInterestingly, all the electrons on octdong Fermi surfaces are described by\ntwo-dimensional massless Dirac Hamiltonians. These materials support quantized\noptical conductance in thin films. We further show that KNLMs can be regarded\nas parent states of KWSs. Therefore, we conclude that all non-centrosymmetric\nmetals with SOC are topological, as they can be either KWSs or KNLMs."
    },
    {
        "anchor": "Photon emission in the graphene under the action of a quasiconstant\n  external electric field: Following a nonperturbative formulation of strong-field QED developed in our\nearlier works, and using the Dirac model of the graphene, we construct a\nreduced QED_{3,2} to describe one species of the Dirac fermions in the graphene\ninteracting with an external electric field and photons. On this base, we\nconsider the photon emission in this model and construct closed formulas for\nthe total probabilities. Using the derived formulas, we study probabilities for\nthe photon emission by an electron and for the photon emission accompanying the\nvacuum instability in the quasiconstant electric field that acts in the\ngraphene plane during the time interval T. We study angular and polarization\ndistribution of the emission as well as emission characteristics in a high\nfrequency and low frequency approximations. We analyze the applicability of the\npresented calculations to the graphene physics in laboratory conditions. In\nfact, we are talking about a possible observation of the Schwinger effect in\nthese conditions.",
        "positive": "Spin-dependent localization of helical edge states in a non-Hermitian\n  phononic crystal: As a distinctive feature unique to non-Hermitian systems, non-Hermitian skin\neffect displays fruitful exotic phenomena in one or higher dimensions,\nespecially when conventional topological phases are involved. Among them,\nhybrid skin-topological effect is theoretically proposed recently, which\nexhibits anomalous localization of topological boundary states at\nlower-dimensional boundaries accompanied by extended bulk states. Here we\nexperimentally realize the hybrid skin-topological effect in a non-Hermitian\nphononic crystal. The phononic crystal, before tuning to be non-Hermitian, is\nan ideal acoustic realization of the Kane-Mele model, which hosts gapless\nhelical edge states at the boundaries. By introducing a staggered distribution\nof loss, the spin-dependent edge modes pile up to opposite corners, leading to\na direct observation of the spin-dependent hybrid skin-topological effect. Our\nwork highlights the interplay between topology and non-Hermiticity and opens\nnew routes to non-Hermitian wave manipulations."
    },
    {
        "anchor": "Static and dynamic properties of bimerons in a frustrated ferromagnetic\n  monolayer: Magnetic bimeron is a topological counterpart of skyrmions in in-plane\nmagnets, which can be used as a spintronic information carrier. We report the\nstatic properties of bimerons with different topological structures in a\nfrustrated ferromagnetic monolayer, where the bimeron structure is\ncharacterized by the vorticity $Q_{\\text{v}}$ and helicity $\\eta$. It is found\nthat the bimeron energy increases with $Q_{\\text{v}}$, and the energy of an\nisolated bimeron with $Q_{\\text{v}}=\\pm 1$ depends on $\\eta$. We also report\nthe dynamics of frustrated bimerons driven by the spin-orbit torques, which\ndepend on the strength of the dampinglike and fieldlike torques. We find that\nthe isolated bimeron with $Q_{\\text{v}}=\\pm 1$ can be driven into linear or\nelliptical motion when the spin polarization is perpendicular to the easy axis.\nWe numerically reveal the damping dependence of the bimeron Hall angle driven\nby the dampinglike torque. Besides, the isolated bimeron with $Q_{\\text{v}}=\\pm\n1$ can be driven into rotation by the dampinglike torque when the spin\npolarization is parallel to the easy axis. The rotation frequency is\nproportional to the driving current density. In addition, we numerically\ndemonstrate the possibility of creating a bimeron state with a higher or lower\ntopological charge by the current-driven collision and merging of bimeron\nstates with different $Q_{\\text{v}}$. Our results could be useful for\nunderstanding the bimeron physics in frustrated magnets.",
        "positive": "Robust and Pristine Top ological Dirac Semimetal Phase in Pressured\n  Two-Dimensional Black Phosphorous: Very recently, in spite of various efforts in searching for two dimensional\ntopological Dirac semimetals (2D TDSMs) in phosphorene, there remains a lack of\nexperimentally efficient way to activate such phase transition and the\nunderlying mechanism for the topological phase acquisition is still\ncontroversial. Here, from first-principles calculations in combination with a\nband-sorting technique based on k.p theory, a layer-pressure topological phase\ndiagram is obtained and some of the controversies are clarified. We demonstrate\nthat, compared with tuning by external electric-fields, strain or doping by\nadsorption, hydrostatic pressure can be an experimentally more feasible way to\nactivate the topological phase transition for 2D TDSM acquisition in\nphosphorene. More importantly, the resultant TDSM state is a pristine phase\npossessing a single pair of symmetry-protected Dirac cones right at the Fermi\nlevel, in startling contrast to the pressured bulk black phosphorous where only\na carrier-mixed Dirac state can be obtained. We corroborate that the Dirac\npoints are robust under external perturbation as long as the glide-plane\nsymmetry preserves. Our findings provide a means to realize 2D pristine TDSM in\na more achievable manner, which could be crucial in the realization of\ncontrollable TDSM states in phosphorene and related 2D materials."
    },
    {
        "anchor": "Cyclostationary measurement of low-frequency odd moments of current\n  fluctuations: Measurement of odd moments of current fluctuations is difficult due to strict\nrequirements for band-pass filtering. We propose how these requirements can be\novercome using cyclostationary driving of the measured signal and indicate how\nthe measurement accuracy can be tested through the phase dependence of the\nmoments of the fluctuations. We consider two schemes, the mixing scheme and the\nstatistics scheme, where the current statistics can be accessed. We also\naddress the limitations of the schemes, due to excess noise and due to the\neffects of the environment, and, finally, discuss the required measurement\ntimes for typical setups.",
        "positive": "A Majorana smoking gun for the superconductor-semiconductor hybrid\n  topological system: Recent observations of a zero bias conductance peak in tunneling transport\nmeasurements in superconductor--semiconductor nanowire devices provide evidence\nfor the predicted zero--energy Majorana modes, but not the conclusive proof for\ntheir existence. We establish that direct observation of a splitting of the\nzero bias conductance peak can serve as the smoking gun evidence for the\nexistence of the Majorana mode. We show that the splitting has an oscillatory\ndependence on the Zeeman field (chemical potential) at fixed chemical potential\n(Zeeman field). By contrast, when the density is constant rather than the\nchemical potential -- the likely situation in the current experimental set-ups\n-- the splitting oscillations are generically suppressed. Our theory predicts\nthe conditions under which the splitting oscillations can serve as the smoking\ngun for the experimental confirmation of the elusive Majorana mode."
    },
    {
        "anchor": "The magnonic limit of domain wall propagation in ferromagnetic nanotubes: We report a study on the field-driven propagation of vortex-like domain walls\nin ferromagnetic nanotubes. This particular geometry gives rise to a special\nfeature of the static wall configuration, which significantly influences its\ndynamics. Unlike domain walls in flat strips, the left-right symmetry of domain\nwall propagation is broken. Furthermore, the domain wall velocity is not\nlimited by the Walker breakdown. Under sufficiently large magnetic fields, the\ndomain wall velocity reaches the velocity of spin waves (about 1000 m/s) and is\nthereafter connected with a direct emission of spin waves. The moving domain\nwall maintains its main structure but has characteristic spin-wave tails\nattached. The spatial profile of this topological soliton is determined by the\nspin-wave dispersion.",
        "positive": "Controlled imprisonment of wave packet and flat bands in a fractal\n  geometry: The explicit construction of non-dispersive flat band modes and the\ntunability of has been reported for a hierarchical 3-simplex fractal geometry.\nA single band tight binding Hamiltonian defined for the deterministic\nself-similar non-translationally invariant network can give rise to a countably\ninfinity of such self localized eigenstates for which the wave packet gets\ntrapped inside a characteristic cluster of atomic sites. An analytical\nprescription to detect those dispersionless states has been demonstrated\nelaborately. The states are localized over clusters of increasing sizes,\ndisplaying the existence of a multitude of localization areas. The onset of\nlocalization can, in principle, be delayed in space by an appropriate choice of\nthe energy of the electron. The response of the system with the modulation of\nthe anisotropy parameter is also studied. Supportive calculation of spectral\nlandscape and demonstration of band dispersion plot are presented to solidify\nthe analytical results. Variation of effective mass tensor cites re-entrant\nbehavior with respect to the modulation of off-diagonal anisotropy. The\ntunability of those states leads to the controlled decay of wave function\nenvelope. The impact of uniform magnetic perturbation on the bound states has\nalso been discussed. Continuous variation of flux modulates the position of the\nflat band modes. The macroscopic degeneracy associated with the modes is\nretained with respect to the application of perturbation."
    },
    {
        "anchor": "Doping controlled Fano resonance in bilayer 1T$ ^{\\prime} $-ReS$ _{2} $:\n  Raman experiments and first-principles theoretical analysis: In the bilayer ReS$ _{2} $ channel of a field-effect transistor (FET), we\ndemonstrate using Raman spectroscopy that electron doping (n) results in\nsoftening of frequency and broadening of linewidth of the in-plane vibrational\nmodes, leaving out-of-plane vibrational modes unaffected. Largest change is\nobserved for the in-plane Raman mode at $\\sim$ 151 cm$^{-1} $, which also shows\ndoping induced Fano resonance with the Fano parameter 1/q = -0.17 at doping\nconcentration of $\\sim 3.7\\times10^{13}$ cm$^{-2} $. A quantitative\nunderstanding of our results is provided by first-principles density functional\ntheory (DFT), showing that the electron-phonon coupling (EPC) of in-plane modes\nis stronger than that of out-of-plane modes, and its variation with doping is\nindependent of the layer stacking. The origin of large EPC is traced to 1T to\n1T$ ^{\\prime} $ structural phase transition of ReS$ _{2} $ involving in-plane\ndisplacement of atoms whose instability is driven by the nested Fermi surface\nof the 1T structure. Results are also compared with the isostructural trilayer\nReSe$ _{2} $.",
        "positive": "Universal spin-Hall conductance fluctuations in two dimensions: We report a theoretical investigation on spin-Hall conductance fluctuation of\ndisordered four terminal devices in the presence of Rashba or/and Dresselhaus\nspin-orbital interactions in two dimensions. As a function of disorder, the\nspin-Hall conductance $G_{sH}$ shows ballistic, diffusive and insulating\ntransport regimes. For given spin-orbit interactions, a universal spin-Hall\nconductance fluctuation (USCF) is found in the diffusive regime. The value of\nthe USCF depends on the spin-orbit coupling $t_{so}$, but is independent of\nother system parameters. It is also independent of whether Rashba or\nDresselhaus or both spin-orbital interactions are present. When $t_{so}$ is\ncomparable to the hopping energy $t$, the USCF is a universal number $\\sim 0.18\ne/4\\pi$. The distribution of $G_{sH}$ crosses over from a Gaussian distribution\nin the metallic regime to a non-Gaussian distribution in the insulating regime\nas the disorder strength is increased."
    },
    {
        "anchor": "Phenomenology of Majorana zero modes in full-shell hybrid nanowires: Full-shell nanowires have been proposed as an alternative nanowire design in\nthe search of topological superconductivity and Majorana zero modes (MZMs).\nThey are hybrid nanostructures consisting of a semiconductor core fully covered\nby a thin superconductor shell and subject to a magnetic flux. In this work we\ncritically examine this proposal, finding a very rich spectral phenomenology\nthat combines the Little-Parks modulation of the parent-gap superconductor with\nflux, the presence of flux-dispersing Caroli-de Gennes-Matricon (CdGM) analog\nsubgap states, and the emergence of MZMs across finite flux intervals that\ndepend on the transverse wavefunction profile of the charge density in the core\nsection. Through microscopic simulations and analytical derivations, we study\ndifferent regimes for the semiconductor core, ranging from the hollow-core\napproximation, to the tubular-core nanowire appropriate for a semiconductor\ntube with an insulating core, to the solid-core nanowire. We compute the phase\ndiagrams for the different models in cylindrical nanowires and find that MZMs\ntypically coexist with CdGM analogs at zero energy, rendering them gapless.\nHowever, we also find topologically protected parameter regions, or islands,\nwith gapped MZMs. In this sense, the most promising candidate to obtain\ntopologically protected MZMs in a full-shell geometry is the nanowire with a\ntubular-shaped core. Moving beyond pristine nanowires, we study the effect of\nmode mixing perturbations. Strikingly, mode mixing can act like a topological\n$p$-wave pairing between particle-hole Bogoliubov partners, and is therefore\nable to create new topologically protected MZMs in regions of the phase diagram\nthat were originally trivial. As a result, the phase diagram is utterly\ntransformed and exhibits protected MZMs in around half of the parameter space.",
        "positive": "Comparative analysis of electric field influence on the quantum wells\n  with different boundary conditions. I. Energy spectrum, quantum information\n  entropy and polarization: Analytical solutions of the Schr\\\"{o}dinger equation for the one-dimensional\nquantum well with all possible permutations of the Dirichlet and Neumann\nboundary conditions (BCs) in perpendicular to the interfaces uniform electric\nfield $\\mathscr{E}$ are used for the comparative investigation of their\ninteraction and its influence on the properties of the system. Limiting cases\nof the weak and strong voltages allow an easy mathematical treatment and its\nclear physical explanation; in particular, for the small $\\mathscr{E}$, the\nperturbation theory derives for all geometries a linear dependence of the\npolarization on the field with the BC-dependent proportionality coefficient\nbeing positive (negative) for the ground (excited) states. Simple two-level\napproximation elementary explains the negative polarizations as a result of the\nfield-induced destructive interference of the unperturbed modes and shows that\nin this case the admixture of only the neighboring states plays a dominant\nrole. Different magnitudes of the polarization for different BCs in this regime\nare explained physically and confirmed numerically. Hellmann-Feynman theorem\nreveals a fundamental relation between the polarization and the speed of the\nenergy change with the field. It is proved that zero-voltage position entropies\n$S_x$ are BC independent and for all states but the ground Neumann level (which\nhas $S_x=0$) are equal to $\\ln2-1$ while the momentum entropies $S_k$ depend on\nthe edge requirements and the level. Varying electric field changes position\nand momentum entropies in the opposite directions such that the entropic\nuncertainty relation is satisfied."
    },
    {
        "anchor": "Length Dependent Thermal Conductivity Measurements Yield Phonon Mean\n  Free Path Spectra in Nanostructures: Thermal conductivity measurements over variable lengths on nanostructures\nsuch as nanowires provide important information about the mean free paths\n(MFPs) of the phonons responsible for heat conduction. However, nearly all of\nthese measurements have been interpreted using an average MFP even though\nphonons in many crystals possess a broad MFP spectrum. Here, we present a\nreconstruction method to obtain MFP spectra of nanostructures from\nvariable-length thermal conductivity measurements. Using this method, we\ninvestigate recently reported length-dependent thermal conductivity\nmeasurements on SiGe alloy nanowires and suspended graphene ribbons. We find\nthat the recent measurements on graphene imply that 70 % of the heat in\ngraphene is carried by phonons with MFPs longer than 1 micron.",
        "positive": "Spin-orbit-torque driven magnetoimpedance in Pt-layer/magnetic-ribbon\n  heterostructures: When a flow of electron passes through a paramagnetic layer with strong\nspin-orbit-coupling such as platinum (Pt), a net spin current is produced via\nspin Hall effect (SHE). This spin current can exert a torque on the\nmagnetization of an adjacent ferromagnetic layer which can be probed via\nmagnetization dynamic response, e.g. spin-torque ferromagnetic resonance\n(ST-FMR). Nevertheless, that effect in lower frequency magnetization dynamic\nregime (MHz) where skin effect occurs in high permeability ferromagnetic\nconductors namely the magneto-impedance (MI) effect can be fundamentally\nimportant which has not been studied so far. Here, by utilizing the MI effect\nin magnetic-ribbon/Pt heterostructure with high magnetic permeability that\nallows the ac current effectively confined at the skin depth of ~100 nm\nthickness, the effect of spin-orbit-torque (SOT) induced by the SHE probed via\nMI measurement is investigated. We observed a systematic MI frequency shift\nthat increases by increasing the applied current amplitude and thickness of the\nPt layer (varying from 0 nm to 20 nm). In addition, the role of Pt layer in\nribbon/Pt heterostructure is evaluated with ferromagnetic resonance (FMR)\neffect representing standard Gilbert damping increase as the result of presence\nof the SHE. Our results unveil the role of SOT in dynamic control of the\ntransverse magnetic permeability probed with impedance spectroscopy as useful\nand valuable technique for detection of future SHE devices."
    },
    {
        "anchor": "The classification of surface states of topological insulators and\n  superconductors with magnetic point group symmetry: We present the exhaustive classification of surface states of topological\ninsulators and superconductors protected by crystallographic magnetic point\ngroup symmetry in three spatial dimensions. Recently, Cornfeld and Chapman\n[Phys. Rev. B {\\bf 99}, 075105 (2019)] pointed out that the topological\nclassification of mass terms of the Dirac Hamiltonian with point group symmetry\nis recast as the extension problem of the Clifford algebra, and we use their\nresults extensively. Comparing two-types of Dirac Hamiltonians with and without\nthe mass-hedgehog potential, we establish the irreducible character formula to\nread off which Hamiltonian in the whole $K$-group belongs to fourth-order\ntopological phases in three spatial dimensions, which are equivalent to atomic\ninsulators consisting of atoms localized at the point group center.",
        "positive": "Chiral electromagnetic waves at the boundary of optical isomers: Quantum\n  Cotton-Mouton effect: We demonstrate that the boundary of two optical isomers with opposite\ndirections of the gyration vectors (both parallel to boundary) can support\npropagation of electromagnetic wave in the direction perpendicular to the\ngyration axes (Cotton-Mouton geometry). The components of electromagnetic field\nin this wave decay exponentially into both media. The characteristic decay\nlength is of the order of the Faraday rotation length for the propagation along\nthe gyration axis. The remarkable property of the boundary wave is its\nchirality. Namely, the wave can propagate only in one direction determined by\nthe relative sign of non-diagonal components of the dielectric tensor in\ncontacting media. We find the dispersion law of the boundary wave for the cases\nof abrupt and smooth boundaries. We also study the effect of asymmetry between\nthe contacting media on the boundary wave and generalize the result to the case\nof two parallel boundaries. Finally we consider the arrangement when the\nboundaries form a random network. We argue that at a point, when this network\npercolates, the corresponding boundary waves undergo quantum delocalization\ntransition, similar to the quantum Hall transition."
    },
    {
        "anchor": "Superradiance Transition in Photosynthetic Light-Harvesting Complexes: We investigate the role of long-lasting quantum coherence in the efficiency\nof energy transport at room temperature in Fenna-Matthews-Olson photosynthetic\ncomplexes. The excitation energy transfer due to the coupling of the light\nharvesting complex to the reaction center (\"sink\") is analyzed using an\neffective non-Hermitian Hamiltonian. We show that, as the coupling to the\nreaction center is varied, maximal efficiency in energy transport is achieved\nin the vicinity of the superradiance transition, characterized by a segregation\nof the imaginary parts of the eigenvalues of the effective non-Hermitian\nHamiltonian. Our results demonstrate that the presence of the sink (which\nprovides a quasi--continuum in the energy spectrum) is the dominant effect in\nthe energy transfer which takes place even in absence of a thermal bath. This\napproach allows one to study the effects of finite temperature and the effects\nof any coupling scheme to the reaction center. Moreover, taking into account a\nrealistic electric dipole interaction, we show that the optimal distance from\nthe reaction center to the Fenna-Matthews-Olson system occurs at the\nsuperradiance transition, and we show that this is consistent with available\nexperimental data.",
        "positive": "Thermal conductance in a spin-boson model: Cotunneling and low\n  temperature properties: Bosonic thermal transport through a two-level system is analyzed at\ntemperatures below and comparable to the two-level energy splitting. It is\nshown that in the low-temperature regime transport is dominated by correlated\ntwo-boson processes analogous to electron cotunneling in quantum dots under\nCoulomb blockade. We present a detailed analysis of the sequential-cotunneling\ncrossover and obtain essentially an analytic description of the transport\nproblem. Perturbative analysis is complemented by employing scaling properties\nof the Ohmic spin-boson model, allowing us to extract an anomalous low\ntemperature scaling of thermal conductance."
    },
    {
        "anchor": "Study of couplings effect on the performance of a spin-current diode:\n  Nonequilibrium Green's function based model: In this paper, spin-dependent transport through a spin diode composed of a\nquantum dot coupled to a normal metal and a ferromagnetic lead is studied. The\ncurrent polarization and the spin accumulation are analyzed using the equations\nof motion method within the nonequilibrium Green's function formalism. We\npresent a suitable method for computing Green's function without carrying out\nany self-consistent calculation. The influence of coupling strength and\nmagnetic field on the spin current is studied and observed that this device\ncannot work as a spin diode under certain conditions.",
        "positive": "Spin rotation by resonant electric field in few-level quantum dots:\n  Floquet dynamics and tunneling: We study electric dipole spin resonance caused by sub-terahertz (THz)\nradiation in a multilevel finite-size quantum dot formed in a nanowire focusing\non the range of driving electric fields amplitudes where a strong interplay\nbetween the Rabi spin oscillations and tunneling from the dot to continuum\nstates can occur. A strong effect of the tunneling on the spin evolution in\nthis regime occurs due to formation of mixed spin states. As a result, the\ntunneling strongly limits possible spin manipulations time. We demonstrate a\nbackaction of the spin dynamics on the tunneling and position of the electron.\nThe analysis of the efficiency of the spin manipulation in terms of the system\nenergy shows that tunneling decreases this efficiency. Fourier spectra of the\ntime-dependent expectation value of the electron position show a strong effect\nof the spin-orbit coupling on their low-frequency components. This results can\nbe applied to operational properties of spin-based nanodevices and extending\nthe range of possible spin resonance frequencies to the THz domain."
    },
    {
        "anchor": "Exploiting anisotropic Rashba effects on real-time photocurrents and\n  spin polarization for transient symmetry breaking: We theoretically investigate the real-time transient responses of a\ntwo-dimensional (2D) electron gas with anisotropic Rashba spin-orbit coupling\n(SOC) to laser pulses. Through explicitly monitoring the time-dependent\nphotocurrents and spin polarization under different linear polarizations of the\nlaser pulse, we find that the transient breaking of the mirror symmetry in\ncombination with the anisotropy of the Rashba SOC results in significant\ndistinction between the charge-mediated and the spin-mediated contributions to\nthe photocurrents. Such distinction is obtained by analyzing the dependence of\nthe symmetry-breaking induced (transverse) components of the photocurrents on\nthe linear polarization angle of the laser pulse. This suggests a possibility\nof inferring spin-mediated processes in photocurrents without the use of\ncircularly polarized lights. Moreover, the interplay between transient symmetry\nbreaking and the anisotropy of the Rashba SOC also leads to transiently nonzero\nspin polarization components that are otherwise zero in the steady-state limit\nand the linear response regime. Especially, the out-of-plane spin polarization\ncomponent can be induced or turned off by controlling the relative orientation\nof the linear polarization with respect to the symmetry axis of the 2D\nelectronic system, without involving material-intrinsic magnetization effects.\nOur findings demonstrate the efficacy of a particular coordination between the\npolarization of the ultrafast laser pulses and the spatial symmetry of the\nelectronic materials in directing the real-time charge and the spin responses\nthat are fundamental to the development of ultrafast spintronics in solid\nstates.",
        "positive": "Magnetoelectric effect in topological insulator films beyond the linear\n  response regime: We study the response of topological insulator films to strong magnetic and\nelectric fields beyond the linear response theory. As a model, we use the\nthree-dimensional lattice Wilson-Dirac Hamiltonian where we simultaneously\nintroduce both magnetic field through the Peierls substitution and electric\nfield as a potential energy depending on lattice coordinate. We compute the\nelectron energy spectrum by numerically diagonalizing this Hamiltonian and\nobtain quantized magnetoelectric polarizability. In addition, we find that the\nmagnetoelectric effect vanishes as the film width decreases due to the\nhybridization of surface wave functions. Furthermore, applying a gate voltage\nbetween the surfaces, we observe several quantized plateaus of $\\theta$ term,\nwhich are mainly determined by the Landau level structures on the top and\nbottom surfaces."
    },
    {
        "anchor": "Boltzmann approach to spin-orbit-induced transport in effective quantum\n  theories: In model studies of the spin/anomalous Hall effect, effective Hamiltonians\noften serve as the starting point. However, a complete effective quantum theory\ncontains not only the effective Hamiltonian but also the relation linking the\nphysical observables to the canonical ones. We construct the semiclassical\nBoltzmann (SB) transport framework in the weak disorder-potential regime\ndirectly in the level of the effective quantum theory, and confirm this\nconstruction by formulating a generalized Kohn-Luttinger density matrix\ntransport theory also in this level. The link and difference between the\npresent SB theory and previous phenomenological Boltzmann, quantum kinetic and\nusual Kubo-Streda theories are clarified. We also present the slightly\ngeneralized Kubo-Streda formula in the level of the effective quantum theory.\nIn this level, it is the generalized Kubo-Streda formula rather than the usual\none that leads to the same physical interpretations as the present SB theory.\nIn the application to a Rashba 2D effective model, a nonzero spin Hall effect\nimportant in the case of strong Rashba coupling but neglected in previous\ntheories is found.",
        "positive": "Controlled Population of Floquet-Bloch States via Coupling to Bose and\n  Fermi Baths: External driving is emerging as a promising tool for exploring new phases in\nquantum systems. The intrinsically non-equilibrium states that result, however,\nare challenging to describe and control. We study the steady states of a\nperiodically driven one-dimensional electronic system, including the effects of\nradiative recombination, electron-phonon interactions, and the coupling to an\nexternal fermionic reservoir. Using a kinetic equation for the populations of\nthe Floquet eigenstates, we show that the steady-state distribution can be\ncontrolled using the momentum and energy relaxation pathways provided by the\ncoupling to phonon and Fermi reservoirs. In order to utilize the latter, we\npropose to couple the system and reservoir via an energy filter which\nsuppresses photon-assisted tunneling. Importantly, coupling to these reservoirs\nyields a steady state resembling a band insulator in the Floquet basis. The\nsystem exhibits incompressible behavior, while hosting a small density of\nexcitations. We discuss transport signatures, and describe the regimes where\ninsulating behavior is obtained. Our results give promise for realizing Floquet\ntopological insulators."
    },
    {
        "anchor": "Spin-polarized antichiral exciton-polariton edge states: We consider theoretically a system of exciton-polariton micropillars arranged\nin a honeycomb lattice. The naturally present TE-TM splitting and an\nalternating Zeeman splitting, where the different sublattices experience\nopposite Zeeman splitting, shifts the Dirac points in energy, giving rise to\nantichiral behavior. In a strip geometry having zigzag edges, two pairs of edge\nstates exist and propagate in the same direction (including the states at the\nopposite edges). The edge modes localized at the opposite edges have opposite\nspins (circular polarizations), which leads to co-propagating \"+-\" spin\nchannels. The antichiral edge states are protected by non-zero winding numbers\nand can propagate around a 60 degree bend without being reflected. We further\ncompare the transport properties of these edge states with chiral edge modes\nand propose a scheme to realize them experimentally.",
        "positive": "Chiral Optical Response of Multifold Fermions: Multifold fermions are generalizations of two-fold degenerate Weyl fermions\nwith three-, four-, six- or eight-fold degeneracies protected by crystal\nsymmetries, of which only the last type is necessarily non-chiral. Their low\nenergy degrees of freedom can be described as emergent particles not present in\nthe Standard Model of particle physics. We propose a range of experimental\nprobes for multifold fermions in chiral symmetry groups based on the gyrotropic\nmagnetic effect (GME) and the circular photo-galvanic effect (CPGE). We find\nthat, in contrast to Weyl fermions, multifold fermions can have zero Berry\ncurvature yet a finite GME, leading to an enhanced response. The CPGE is\nquantized and independent of frequency provided that the frequency region at\nwhich it is probed defines closed optically-activated momentum surfaces. We\nconfirm the above properties by calculations in symmetry-restricted tight\nbinding models with realistic density functional theory parameters. We identify\na range of previously-unidentified ternary compounds able to exhibit chiral\nmultifold fermions of all types (including a range of materials in the families\nAsBaPt and Gd$_3$Cl$_3$C), and provide specific predictions for the known\nmultifold material RhSi."
    },
    {
        "anchor": "Floquet Cavity Electromagnonics: Hybrid magnonics has recently attracted intensive attentions as a promising\nplatform for coherent information processing. In spite of its rapid\ndevelopment, on-demand control over the interaction of magnons with other\ninformation carriers, in particular microwave photons in electromagnonic\nsystems, has been long missing, significantly limiting the broad applications\nof hybrid magnonics. Here, we show that by introducing Floquet engineering into\ncavity electromagnonics, coherent control on the magnon-microwave photon\ncoupling can be realized. Leveraging the periodic temporal modulation from a\nFloquet drive, our first-of-its-kind Floquet cavity electromagnonic system can\nmanipulate the interaction between hybridized cavity electromagnonic modes on\ndemand. Moreover, we demonstrate a new coupling regime in such systems: the\nFloquet ultrastrong coupling, where the Floquet splitting is comparable with or\neven larger than the level spacing of the two interacting modes, resulting in\nthe breakdown of the rotating wave approximation. Our findings open up new\ndirections for magnon-based coherent signal processing.",
        "positive": "Quantum computation with doped silicon cavities: We propose a quantum computer architecture involving substitutional donors in\nphotonic-crystal silicon cavities and the optical initialization, manipulation,\nand detection processes already demonstrated in ion traps and other atomic\nsystems. Our scheme considerably simplifies the implementation of the building\nblocks for the successful operation of silicon-based solid-state quantum\ncomputers, including positioning of the donors, realization of one- and\ntwo-qubit gates, initialization and readout of the qubits. Detailed\nconsideration of the processes involved, using state-of-the-art values for the\nrelevant parameters, indicates that this architecture might lead to errors per\ngate compatible with scalable quantum computation."
    },
    {
        "anchor": "Twisted magnon as a magnetic tweezer: Wave fields with spiral phase dislocations carrying orbital angular momentum\n(OAM) have been realized in many branches of physics, such as for photons,\nsound waves, electron beams, and neutrons. However, the OAM states of magnons\n(spin waves)$-$the building block of modern magnetism$-$and particularly their\nimplications have yet to be addressed. Here, we theoretically investigate the\ntwisted spin-wave generation and propagation in magnetic nanocylinders. The OAM\nnature of magnons is uncovered by showing that the spin-wave eigenmode is also\nthe eigenstate of the OAM operator in the confined geometry. Inspired by\noptical tweezers, we predict an exotic \"magnetic tweezer\" effect by showing\nskyrmion gyrations under twisted magnons in exchange coupled\nnanocylinder$|$nanodisk heterostructure, as a practical demonstration of\nmagnonic OAM to manipulate topological spin defects. Our study paves the way\nfor the emerging magnetic manipulations by harnessing the OAM degree of freedom\nof magnons.",
        "positive": "Topological metals induced by Zeeman effect: In the present paper, we propose a new way to classify centrosymmetric metals\nby studying the Zeeman effect caused by an external magnetic field described by\nthe momentum dependent g-factor tensor on the Fermi surfaces. Nontrivial U(1)\nBerry's phase and curvature can be generated once the otherwise degenerate\nFermi surfaces are splitted by the Zeeman effect, which will be determined by\nboth the intrinsic band structure and the structure of g-factor tensor on the\nmanifold of the Fermi surfaces. Such Zeeman effect generated Berry's phase and\ncurvature can lead to three important experimental effects, modification of\nspin-zero effect, Zeeman effect induced Fermi surface Chern number and the\nin-plane anomalous Hall effect. By first principle calculations, we study all\nthese effects on two typical material, ZrTe$_5$ and TaAs$_2$ and the results\nare in good agreement with the existing experiments."
    },
    {
        "anchor": "Mesoscopic Stoner instability in metallic nanoparticles revealed by shot\n  noise: We study sequential tunneling through a metallic nanoparticle close to the\nStoner instability coupled to parallely magnetized electrodes. Increasing the\nbias voltage successively opens transport channels associated with excitations\nof the nanoparticle's total spin. For the current this leads just to a steplike\nincrease. The Fano factor, in contrast, shows oscillations between large\nsuper-Poissonian and sub-Poissonian values as a function of bias voltage. We\nexplain the enhanced Fano factor in terms of generalized random-telegraph noise\nand propose the shot noise as a convenient tool to probe the mesoscopic Stoner\ninstability.",
        "positive": "Resonant dynamics of skyrmion lattices in thin film multilayers:\n  Localised modes and spin wave emission: The spectral signatures of magnetic skyrmions under microwave field\nexcitation are of fundamental interest and can be an asset for high frequency\napplications. These topological solitons can be tailored in multilayered thin\nfilms, but the experimental observation of their spin wave dynamics remains\nelusive, in particular due to large damping. Here, we study Pt/FeCoB/AlO$_x$\nmultilayers hosting dense and robust skyrmion lattices at room temperature with\nGilbert damping of $\\sim 0.02$. We use magnetic force microscopy to\ncharacterise their static magnetic phases and broadband ferromagnetic resonance\nto probe their high frequency response. Micromagnetic simulations reproduce the\nexperiments with accuracy and allow us to identify distinct resonant modes\ndetected in the skyrmion lattice phase. Low ($<$ 2 GHz) and intermediate\nfrequency ($2-8$ GHz) modes involve excitations localised to skyrmion edges in\nconjunction with precession of the uniform background magnetisation, while a\nhigh frequency ($>$ 12 GHz) mode corresponds to in-phase skyrmion core\nprecession emitting spin waves into uniform background with wavelengths in the\n50--80 nm range commensurate with the lattice structure. These findings could\nbe instrumental in the investigation of room temperature wave scattering and\nthe implementation of novel microwave processing schemes in reconfigurable\narrays of solitons."
    },
    {
        "anchor": "Conductance quantization and transport gap in disordered graphene\n  nanoribbons: We study numerically the effects of edge and bulk disorder on the conductance\nof graphene nanoribbons. We compute the conductance suppression due to\nlocalization induced by edge scattering. We find that even for weak edge\nroughness, conductance steps are suppressed and transport gaps appear. These\ngaps are approximately inversely proportional to the nanoribbon width. On/off\nconductance ratios grow exponentially with the nanoribbon length. Our results\nimpose severe limitations to the use of graphene in ballistic nanowires.",
        "positive": "Very low critical current density for motion of coupled domain walls in\n  synthetic ferrimagnet nanowires: Domain walls in ferromagnetic nanowires are potential building-blocks of\nfuture technologies such as racetrack memories, in which data encoded in the\ndomain walls are transported using spin-polarised currents. However, the\ndevelopment of energy-efficient devices has been hampered by the high current\ndensities needed to initiate domain wall motion. We show here that a remarkable\nreduction in the critical current density can be achieved for in-plane\nmagnetised coupled domain walls in CoFe/Ru/CoFe synthetic ferrimagnet tracks.\nThe antiferromagnetic exchange coupling between the layers leads to simple\nN\\'{e}el wall structures, imaged using photoemission electron and Lorentz\ntransmission electron microscopy, with a width of only $\\sim 100$~nm. The\nmeasured critical current density to set these walls in motion, detected using\nmagnetotransport measurements, is $1.0 \\times 10^{11}$~Am$^{-2}$, almost an\norder of magnitude lower than in a ferromagnetically coupled control sample.\nTheoretical modelling indicates that this is due to nonadiabatic driving of\nanisotropically coupled walls, a mechanism that can be used to design efficient\ndomain-wall devices."
    },
    {
        "anchor": "Levitons in helical liquids with Rashba spin-orbit coupling probed by a\n  superconducting contact: We consider transport properties of a single edge of a two-dimensional\ntopological insulators, in presence of Rashba spin-orbit coupling, driven by\ntwo external time-dependent voltages and connected to a thin superconductor. We\nfocus on the case of a train of Lorentzian-shaped pulses, which are known to\ngenerate coherent single-electron excitations in two-dimensional electron gas,\nand prove that they are minimal excitations for charge transport also in\nhelical edge states, even in the presence of spin-orbit interaction.\nImportantly, these properties of Lorentzian-shaped pulses can be tested\ncomputing charge noise generated by the scattering of particles at the thin\nsuperconductor. This represents a novel setup where electron quantum optics\nexperiments with helical states can be implemented, with the superconducting\ncontact as an effective beamsplitter. By elaborating on this configuration, we\nalso evaluate charge noise in a collisional Hong-Ou-Mandel configuration,\nshowing that, due to the peculiar effects induced by Rashba interaction, a\nnon-vanishing dip at zero delay appears.",
        "positive": "Anomalous spin-orbit field via Rashba-Edelstein effect at W/Pt interface: We have studied spin-orbit (SO) field in Ni$_{80}$Fe$_{20}$(Py)/W/Pt trilayer\nby means of spin-torque ferromagnetic resonance, and demonstrated that the W/Pt\ninterface generates an extra SO field acting on the Py layer. This\nunprecedented field originates from the following three processes, 1) spin\naccumulation at W/Pt interface via the Rashba-Edelstein effect, 2) diffusive\nspin transport in the W layer, and 3) spin absorption into the Py layer through\naccumulation at the Py/W interface. Our result means that we can create extra\nSO field away from the ferromagnet/ metal interface and control its strength by\na combination of two different metals."
    },
    {
        "anchor": "Carbon Nanocone: A Promising Thermal Rectifier: With molecular dynamics simulations, we demonstrate very obvious thermal\nrectification in large temperature range from 200 to 400 K in nanocone. We also\nobserve that the rectification of nanocone does not depend on the length very\nsensitively, which is in stark contrast with the nanotube thermal rectifier in\nwhich the rectification decreases dramatically as the length increases. Our\nwork demonstrates that carbon nanocone is a promising practical phononic\ndevice.",
        "positive": "Thermoelectric properties of graphyne from first-principles calculations: The two-dimensional graphene-like carbon allotrope, graphyne, has been\nrecently fabricated and exhibits many interesting electronic properties. In\nthis work, we investigate the thermoelectric properties of {\\gamma}-graphyne by\nperforming first-principles calculations combined with Boltzmann transport\ntheory for both electron and phonon. The carrier relaxation time is accurately\nevaluated from the ultra-dense electron-phonon coupling matrix elements\ncalculated by adopting the density functional perturbation theory and Wannier\ninterpolation, rather than the generally used deformation potential theory\nwhich only considers the electron-acoustic phonon scattering. It is found that\nthe thermoelectric performance of {\\gamma}-graphyne exhibits a strong\ndependence on the temperature and carrier type. At an intermediate temperature\nof 600 K, a maximum ZT value of 1.5 and 1.0 can be achieved for the p- and\nn-type systems, respectively."
    },
    {
        "anchor": "Surface anisotropy of iron oxide nanoparticles and slabs from first\n  principles : influence of coatings and ligands as a test of the Heisenberg\n  model: We performed ab initio computations of the magnetic properties of simple iron\noxide clusters and slabs. We considered an iron oxide cluster functionalized by\na molecule or glued to a gold cluster of the same size. We also considered a\nmagnetite slab coated by cobalt oxide or a mixture of iron oxide and cobalt\noxide. The changes in magnetic behavior were explored using constrained\nmagnetic calculations. A possible value for the surface anisotropy was\nestimated from the fit of a classical Heisenberg model on ab initio results.\nThe value was found to be compatible with estimations obtained by other means,\nor inferred from experimental results. The addition of a ligand, coating, or of\na metallic nanoparticle to the systems degraded the quality of the description\nby the Heisenberg Hamiltonian. Proposing a change in the anisotropies allowing\nfor the proportion of each transition atom we could get a much better\ndescription of the magnetism of series of hybrid cobalt and iron oxide systems.",
        "positive": "Non-Abelian statistics in the interference noise of the Moore-Read\n  quantum Hall state: We propose noise oscillation measurements in a double point contact,\naccessible with current technology, to seek for a signature of the non-abelian\nnature of the \\nu=5/2 quantum Hall state. Calculating the voltage and\ntemperature dependence of the current and noise oscillations, we predict the\nnon-abelian nature to materialize through a multiplicity of the possible\noutcomes: two qualitatively different frequency dependences of the nonzero\ninterference noise. Comparison between our predictions for the Moore-Read state\nwith experiments on \\nu=5/2 will serve as a much needed test for the nature of\nthe \\nu=5/2 quantum Hall state."
    },
    {
        "anchor": "Optimization of edge state velocity in the integer quantum Hall regime: Observation of interference in the quantum Hall regime may be hampered by a\nsmall edge state velocity due to finite phase coherence time. Therefore\ndesigning two quantum point contact (QPCs) interferometers having a high edge\nstate velocity is desirable. Here, we present a new simulation method for\nrealistically modeling edge states near QPCs in the integer quantum Hall effect\n(IQHE) regime. We calculate the filling fraction in the center of the QPC and\nthe velocity of the edge states, and predict structures with high edge state\nvelocity. The 3D Schr\\\"odinger equation is split into 1D and 2D parts. Quasi-1D\nSchr\\\"odinger and Poisson equations are solved self-consistently in the IQHE\nregime to obtain the potential profile near the edges, and quantum transport is\nused to solve for the edge state wavefunctions. The velocity of edge states is\nfound to be $\\left< E \\right> / B$, where $\\left< E \\right>$ is the expectation\nvalue of the electric field for the edge state. Anisotropically etched trench\ngated heterostructures with double sided delta doping have the highest edge\nstate velocity among the structures considered.",
        "positive": "Impurity induced bound states and proximity effect in a bilayer exciton\n  condensate: The effect of impurities which induce local interlayer tunneling in bilayer\nexciton condensates is discussed. We show that a localized single fermion bound\nstate emerges inside the gap for any strength of impurity scattering and\ncalculate the dependence of the impurity state energy and wave function on the\npotential strength. We show that such an impurity induced single fermion state\nenhances the interlayer coherence around it, and is similar to the\nsuperconducting proximity effect. As a direct consequence of these single\nimpurity states, we predict that a finite concentration of such impurities will\nincrease the critical temperature for exciton condensation."
    },
    {
        "anchor": "Dipolar polaritons in microcavity-embedded coupled quantum wells in\n  electric and magnetic fields: We present a precise calculation of spatially-indirect exciton states in\nsemiconductor coupled quantum wells and polaritons formed from their coupling\nto the optical mode of a microcavity. We include the presence of electric and\nmagnetic fields applied perpendicular to the quantum well plane. Our model\npredicts the existence of polaritons which are in the strong coupling regime\nand at the same time possess a large static dipole moment. We demonstrate, in\nparticular, that a magnetic field can compensate for the reduction in\nlight-matter coupling that occurs when an electric field impresses a dipole\nmoment on the polariton.",
        "positive": "Ordered FePdCu nanoisland arrays made by templated solid-state dewetting: Ordered FePdCu nanoisland arrays were formed by annealing at 600oC, which\ncaused solid state dewetting of [Cu/Fe/Pd] multilayers deposited on\nself-assembled SiO2 nanospheres with size of 100 nm. A single FePdCu island was\nformed on the top of each SiO2 nanosphere. The structure of the obtained system\nwas studied by x-ray diffraction (XRD), while its magnetic properties by SQUID\nmagnetometry. Partially ordered L10 alloy appeared in the annealed films,\nleading to magnetic hardening of the material. The paper presents the influence\nof the patterning on the system properties. It is shown that templated\ndewetting is a method providing nanoislands with well controlled sizes and\npositions. The role of copper admixture in controlling the structural and\nmagnetic properties is also discussed."
    },
    {
        "anchor": "Spin filtering due to quantum interference in periodic mesoscopic\n  networks: We present several new results, extending our recent proposal of a spin\nfilter based on a tight-binding model for a periodic chain of diamond-like\nloops [Phys. Rev. B {\\bf 78}, 125328 (2008)]. In this filter, the Rashba\nspin-orbit interaction (which can be tuned by a perpendicular gate voltage) and\nthe Aharonov-Bohm flux (due to a perpendicular magnetic field) combine to\nselect only one propagating ballistic mode. For this mode, the electronic spins\nare fully polarized along a direction that can be controlled by the electric\nand magnetic fields and by the electron energy. All the other modes are\nevanescent. Generalizing the square diamonds into rhombi with arbitrary opening\nangles, we find that increasing these angles widens the parameter range for\nefficient filtering. A different gate voltage on the two sides of each rhombus\nis found to delocalize the electrons for energies on one side of the band\ncenter. We also compare our tight-binding model with models which use\ncontinuous quantum networks of one-dimensional wires, and find coincidence only\nwhen one chooses particular site energies at the nodes of the network.",
        "positive": "Manipulation of exciton and trion quasiparticles in monolayer WS2 via\n  charge transfer: Charge doping in transition metal dichalcogenide is currently a subject of\nhigh importance for future electronic and optoelectronic applications. Here we\ndemonstrate chemical doping in CVD grown monolayer (1L) of WS2 by a few\ncommonly used laboratory solvents by investigating the room temperature\nphotoluminescence (PL). The appearance of distinct trionic emission in the PL\nspectra and quenched PL intensities suggest n-type doping in WS2. The\ntemperature-dependent PL spectra of the doped 1L-WS2 reveal significant\nenhancement of trion emission intensity over the excitonic emission at low\ntemperature indicating the stability of trion at low temperature. The\ntemperature dependent exciton-trion population dynamic has been modeled using\nthe law of mass action of trion formation. These results shed light on the\nsolution-based chemical doping in 1L WS2 and its profound effect on the\nphotoluminescence which is essential for the control of optical and electrical\nproperties for optoelectronics applications."
    },
    {
        "anchor": "Observation of a two-dimensional electron gas at CaTiO$_3$ film surfaces: The two-dimensional electron gas at the surface of titanates gathered\nattention due to its potential to replace conventional silicon based\nsemiconductors in the future. In this study, we investigated films of the\nparent perovskite CaTiO$_3$, grown by pulsed laser deposition, by means of\nangular-resolved photoelectron spectroscopy. The films show a c(4x2) surface\nreconstruction after the growth that is reduced to a p(2x2) reconstruction\nunder UV-light. At the CaTiO$_3$ film surface, a two-dimensional electron gas\n(2DEG) is found with an occupied band width of 400 meV. With our findings\nCaTiO$_3$ is added to the group of oxides with a 2DEG at their surface. Our\nstudy widens the phase space to investigate strontium and barium doped\nCaTiO$_3$ and the interplay of ferroelectric properties with the 2DEG at oxide\nsurfaces. This could open up new paths to tailor two-dimensional transport\nproperties of these systems towards possible applications.",
        "positive": "Coherence and Spatial Resolution of Transport in Quantum Cascade Lasers: The method of nonequilibrium Greens functions allows for a spatial and\nenergetical resolution of the electron current in Quantum Cascade Lasers. While\nscattering does not change the spatial position of carriers, the entire spatial\nevolution of charge can be attributed to coherent transport by complex wave\nfunctions. We discuss the hierarchy of transport models and derive the density\nmatrix equations as well as the hopping model starting from the nonequilibrium\nGreens functions approach."
    },
    {
        "anchor": "Interfacial amplification for graphene based\n  position-sensitive-detectors: Position-sensitive-detectors (PSDs) based on lateral photoeffect has been\nwidely used in diverse applications, including optical engineering, aerospace\nand military fields. With increasing demand in long distance, low energy\nconsumption, and weak signal sensing systems, the poor responsivity of\nconventional PSDs has become a bottleneck limiting its applications. Herein, we\npresent a high performance graphene based PSDs with revolutionary interfacial\namplification mechanism. Signal amplification in the order of ~10^4 has been\ndemonstrated by utilizing the ultrahigh mobility of graphene and long lifetime\nof photo-induced carriers at the interface of SiO2/Si. This would improve the\ndetection limit of Si-based PSDs from uW to nW level, without sacrificing the\nspatial resolution and response speed. Such interfacial amplification mechanism\nis compatible with current Si technology and can be easily extended to other\nsensing systems.",
        "positive": "Oscillator strengths of dark charged excitons in the quantum Hall regime: By direct absorption spectroscopy and comparison to photoluminescence (PL),\nwe investigate negatively charged excitons in dilute two-dimensional electron\nsystems at temperatures down to T=40 mK in the regime of the fractional quantum\nHall effect. At very low temperatures, for filling factor \\nu < 1/3, an\nadditional excitation appears in the PL spectrum, between the well-known\nsinglet and triplet excitons. The observation of a similar excitation by PL was\nreported very recently [G. Yusa et al., cond-mat0103561], and the excitation\nwas assigned, in spite of a PL intensity similar to that of the neutral\nexciton, to be due to a dark triplet exciton. By comparing PL and direct\nabsorption spectra in optically thin samples at T<100 mK, we can identify the\nnew excitation indeed as a 'dark' mode, since we find that the oscillator\nstrength is much smaller than those of the 'bright' modes."
    },
    {
        "anchor": "Resonant Spin Hall Conductance in Two-Dimensional Electron Systems with\n  Rashba Interaction in a Perpendicular Magnetic Field: We study transport properties of a two-dimensional electron system with\nRashba spin-orbit coupling in a perpendicular magnetic field. The spin orbit\ncoupling competes with Zeeman splitting to introduce additional degeneracies\nbetween different Landau levels at certain magnetic fields. This degeneracy, if\noccuring at the Fermi level, gives rise to a resonant spin Hall conductance,\nwhose height is divergent as 1/T and whose weight is divergent as $-\\ln T$ at\nlow temperatures. The Hall conductance is unaffected by the Rashba coupling.",
        "positive": "Non-linear two-photon resonance fluorescence on a single artificial atom: We report two-photon resonance fluorescence of an individual semiconductor\nartificial atom. By non-linearly driving a single quantum dot via a two-photon\ntransition, we probe the linewidth of the two-photon processes and show that,\nsimilar to their single-photon counterparts, they are close to being Fourier\nlimited at low temperatures. The evolution of the population of excitonic\nstates with the Rabi frequency exhibits a clear s-shaped behavior, indicative\nof the non-linear response via the two-photon excitation process. We model the\nnon-linear response using a 4-level atomic system representing the manifold of\nexcitonic and biexcitonic states of the quantum dot and show that quantitative\nagreement is obtained only by including the interaction with LA-phonons in the\nsolid state environment. Finally, we demonstrate the formation of dressed\nstates emerging from a two-photon interaction between the artificial atom and\nthe excitation field. The non-linear optical dressing induces a mixing of all\nfour excitonic states that facilitates the tuning of the polarization selection\nrules of the artificial atom."
    },
    {
        "anchor": "Modeling quantum cascade lasers: Coupled electron and phonon transport\n  far from equilibrium and across disparate spatial scales: Quantum cascade lasers (QCLs) are high-power coherent light sources in the\nmidinfrared and terahertz parts of the electromagnetic spectrum. They are\ndevices in which the electronic and lattice systems are far from equilibrium,\nstrongly coupled to one another, and the problem bridges disparate spatial\nscales. We present our ongoing work on the multiphysics and multiscale\nsimulation of far-from-equilibrium transport of charge and heat in midinfrared\nQCLs.",
        "positive": "Two dimensional electrons in (100) oriented silicon field effect\n  structures in the region of low concentrations and high mobilities: A comparative analysis of experimental data on electron transport in Si (100)\nMOSFETs in the region of high mobilities and strong electronelectron\ninteraction is carried out. It is shown that electrons can be described by the\nmodel of a noninteracting gas with the renormalized mass and Lande factor,\nwhich allows experimentally verifiable predictions."
    },
    {
        "anchor": "Comment on \"Exact Classification of Landau-Majorana-Stuckelberg-Zener\n  Resonances by Floquet Determinants\": In a recent Letter [S. Ganeshan, E. Barnes, and S. Das Sarma, Phys. Rev.\nLett. 111, 130405 (2013)], Ganeshan et al. present a general framework to\nclassify the resonance structure of Landau-Majorana-Stuckelberg-Zener\ninterferometry into three basic categories distinguished by whether these\nresonances correspond to periodic or nonperiodic quantum evolution. In this\nComment, we show that their identification of the real resonances in the regime\nof small drive amplitude is incorrect.",
        "positive": "Equations of motion approach to decoherence and current noise in\n  ballistic interferometers coupled to a quantum bath: We present a technique for treating many particles moving inside a ballistic\ninterferometer, under the influence of a quantum-mechanical environment\n(phonons, photons, Nyquist noise etc.). Our approach is based on solving the\ncoupled Heisenberg equations of motion of the many-particle system and the bath\nand is inspired by the quantum Langevin method known for the Caldeira Leggett\nmodel. It allows to study decoherence and the influence of the bath on other\nproperties of the interferometer. As a first application, we treat a fermionic\nMach-Zehnder interferometer. In particular, we discuss the dephasing rate and\npresent full analytical expressions for the leading corrections to the current\nnoise, brought about by the coupling to the quantum bath."
    },
    {
        "anchor": "Probing dark exciton navigation through a local strain landscape in a\n  WSe$_2$ monolayer: Monolayers of transition metal dichalcogenides (TMDs) have recently emerged\nas a promising optoelectronic platform. To leverage their full potential,\nhowever, it is important to understand and engineer the properties of the\ndifferent exciton species that exist in these monolayers, as well as to control\ntheir transport through the material. A promising approach relies on\nengineering strain landscapes in atomically thin semiconductors that excitons\nnavigate. In WSe$_2$ monolayers, for example, localized strain has been used to\ncontrol the emission wavelength of excitons, induce exciton funneling and\nconversion, and even realize single-photon sources and quantum dots. Before\nthese phenomena can be fully leveraged for applications, including quantum\ninformation processing, the details of excitons' interaction with the strain\nlandscape must be well understood. To address this, we have developed a\ncryogenic technique capable of probing the dynamics of both bright and dark\nexcitons in nanoscale strain landscapes in TMDs. In our approach, a\nnanosculpted tapered optical fiber is used to simultaneously generate strain\nand probe the near-field optical response of WSe$_2$ monolayers at 5 K. When\nthe monolayer is pushed by the fiber, its lowest energy photoluminescence (PL)\npeaks red shift by as much as 390 meV, (corresponding to 20% of the bandgap of\nan unstrained WSe$_2$ monolayer). The red-shifting peaks are polarized\nperpendicularly to the WSe$_2$ plane and have long rising times (10 ps) and\nlifetimes (52 ps), indicating that they originate from nominally spin-forbidden\ndark excitons. Taken together, these observations indicate that dark excitons\nare funneled to the high-strain regions during their long lifetime and are the\nprincipal participants in drift and diffusion at cryogenic temperatures. Our\nwork elucidates the important role that dark excitons play in locally strained\nWSe$_2$.",
        "positive": "Coulomb blockade in molecular quantum dots: The rate-equation approach is used to describe sequential tunneling through a\nmolecular junction in the Coulomb blockade regime. Such device is composed of\nmolecular quantum dot (with discrete energy levels) coupled with two metallic\nelectrodes via potential barriers. Based on this model, we calculate nonlinear\ntransport characteristics (conductance-voltage and current-voltage dependences)\nand compare them with the results obtained within a self-consistent field\napproach. It is shown that the shape of transport characteristics is determined\nby the combined effect of the electronic structure of molecular quantum dots\nand by the Coulomb blockade. In particular, the following phenomena are\ndiscussed in detail: the suppression of the current at higher voltages, the\ncharging-induced rectification effect, the charging-generated changes of\nconductance gap, and the temperature-induced as well as broadening-generated\nsmoothing of current steps."
    },
    {
        "anchor": "Quasiparticle dynamics in epitaxial Al-InAs planar Josephson junctions: Quasiparticle (QP) effects play a significant role in the coherence and\nfidelity of superconducting quantum circuits. The Andreev bound states of high\ntransparency Josephson junctions can act as low-energy traps for QPs, providing\na mechanism for studying the dynamics and properties of both the QPs and the\njunction. We study the trapping and clearing of QPs from the Andreev bound\nstates of epitaxial Al-InAs Josephson junctions incorporated in a\nsuperconducting quantum interference device (SQUID) galvanically shorting a\nsuperconducting resonator to ground. We use a neighboring voltage-biased\nJosephson junction to inject QPs into the circuit. Upon the injection of QPs,\nwe show that we can trap and clear QPs when the SQUID is flux-biased. We\nexamine effects of the microwave loss associated with bulk QP transport in the\nresonator, QP-related dissipation in the junction, and QP poisoning events. By\nmonitoring the QP trapping and clearing in time, we study the dynamics of these\nprocesses and find a time-scale of few microseconds that is consistent with\nelectron-phonon relaxation in our system and correlated QP trapping and\nclearing mechanisms. Our results highlight the QP trapping and clearing\ndynamics as well as the associated time-scales in high transparency Josephson\njunctions based fabricated on Al-InAs heterostructures.",
        "positive": "Optical absorption in highly-strained Ge/SiGe quantum wells: the role of\n  \u0393-to-\u0394 scattering: We report the observation of the quantum-confined Stark effect in Ge/SiGe\nmultiple quantum well heterostructures grown on Si(0.22)Ge(0.78) virtual\nsubstrates. The large compressive strain in the Ge quantum well layers caused\nby the lattice mismatch with the virtual substrate results in a blue shift of\nthe direct absorption edge, as well as a reduction in the \\Gamma-valley\nscattering lifetime because of strain-induced splittings of the conduction band\nvalleys. We investigate theoretically the \\Gamma-valley carrier lifetimes by\nevaluating the \\Gamma-to-L and \\Gamma-to-\\Delta{} scattering rates in strained\nGe/SiGe semiconductor heterostructures. These scattering rates are used to\ndetermine the lifetime broadening of excitonic peaks and the indirect\nabsorption in simulated absorption spectra, which are compared with measured\nabsorption spectra for quantum well structures with systematically-varied\ndimensions. We find that \\Gamma-to-\\Delta{} scattering is significant in\ncompressively strained Ge quantum wells and that the \\Gamma-valley electron\nlifetime is less than 50 fs in the highly-strained structures reported here,\nwhere \\Gamma-to-\\Delta{} scattering accounted for approximately half of the\ntotal scattering rate."
    },
    {
        "anchor": "Spin wave confinement in hybrid superconductor-ferrimagnet nanostructure: Eddy currents in a superconductor shield the magnetic field in its interior\nand are responsible for the formation of a magnetic stray field outside of the\nsuperconducting structure. The stray field can be controlled by the external\nmagnetic field and affect the magnetization dynamics in the magnetic system\nplaced in its range. In the case of a hybrid system consisting of a\nsuperconducting strip placed over a magnetic layer, we predict theoretically\nthe confinement of spin waves in the well of the static stray field. The number\nof bound states and their frequencies can be controlled by an external magnetic\nfield. We have presented the results of semi-analytical calculations\ncomplemented by numerical modeling.",
        "positive": "Unidirectional magnetoelectric-field multiresonant tunneling: Unidirectional multi-resonant tunneling of the magneto-electric (ME)-field\nexcitations through a sub wavelength (regarding the scales of regular\nelectromagnetic radiation) vacuum or isotropic-dielectric regions has been\nobserved in two-port microwave structures having a quasi-2D ferrite disk with\nmagnetic-dipolar-mode (MDM) oscillations. The excitations manifest themselves\nas the Fano-resonance peaks in the scattering-matrix parameters at the\nstationary states of the MDM spectrum. The ME near-field excitations are quasi\nmagnetostatic fields with non-zero helicity parameter. Topological-phase\nproperties of ME fields are determined by edge chiral currents of MDM\noscillations. We show that while for a given direction of a bias magnetic field\n(in other words, for a given direction of time), the ME-field excitations are\nconsidered as forward tunneling processes, in the opposite direction of a bias\nmagnetic field (the opposite direction of time), there are backward tunneling\nprocesses. Unidirectional ME-field resonant tunneling is observed due to\ndistinguishable topology of the forward and backward ME-field excitations. We\nestablish a close connection between the Fano-resonance unidirectional\ntunneling and topology of ME fields in different microwave structures."
    },
    {
        "anchor": "Optically-Controlled Orbitronics on a Triangular Lattice: The propagation of electrons in an orbital multiplet dispersing on a lattice\ncan support anomalous transport phenomena deriving from an orbitally-induced\nBerry curvature. In striking contrast to the related situation in graphene, we\nfind that anomalous transport for an $L=1$ multiplet on the primitive 2D\ntriangular lattice is activated by easily implemented on-site and\noptically-tunable potentials. We demonstrate this for dynamics in a Bloch band\nwhere point degeneracies carrying opposite winding numbers are generically\noffset in energy, allowing both an anomalous charge Hall conductance with sign\nselected by off-resonance coupling to circularly-polarized light and a related\nanomalous orbital Hall conductance activated by layer buckling.",
        "positive": "Thermal conductance as a probe of the non-local order parameter for a\n  topological superconductor with gauge fluctuations: We investigate the effect of quantum phase slips on a helical quantum wire\ncoupled to a superconductor by proximity. The effective low-energy description\nof the wire is that of a Majorana chain minimally coupled to a dynamical\n$\\mathbb{Z}_2$ gauge field. Hence the wire emulates a matter-coupled gauge\ntheory, with fermion parity playing the role of the gauged global symmetry.\nQuantum phase slips lift the ground state degeneracy associated with unpaired\nMajorana edge modes at the ends of the chain, a change that can be understood\nas a transition between the confined and the Higgs-mechanism regimes of the\ngauge theory. We identify the quantization of thermal conductance at the\ntransition as a robust experimental feature separating the two regimes. We\nexplain this result by establishing a relation between thermal conductance and\nthe Fredenhagen-Marcu string order-parameter for confinement in gauge theories.\nOur work indicates that thermal transport could serve as a measure of non-local\norder parameters for emergent or simulated topological quantum order."
    },
    {
        "anchor": "Upstream neutral modes in the fractional quantum Hall effect regime:\n  heat waves or coherent dipoles: Counter propagating (upstream) chiral neutral edge modes, which were\npredicted to be present in hole-conjugate states, were observed recently in a\nvariety of fractional quantum Hall states (v=2/3,v=3/5,v=8/3 & v=5/2), by\nmeasuring charge noise that resulted after partitioning the neutral mode by a\nconstriction (denoted, as N\\rightarrowC). Particularly noticeable was the\nobservation of such modes in the v=5/2 fractional state - as it sheds light on\nthe non-abelian nature of the state's wavefunction. Yet, the nature of these\nunique, upstream, chargeless modes and the microscopic process in which they\ngenerate shot noise, are not understood. Here, we study the ubiquitous v=2/3\nstate and report of two main observations: First, the nature of the neutral\nmodes was tested by 'colliding' two modes, emanating from two opposing sources,\nin a narrow constriction. The resultant charge noise was consistent with local\nheating of the partitioned quasiparticles. Second, partitioning of a downstream\ncharge mode by a constriction gave birth to a dual process, namely, the\nappearance of an upstream neutral mode (C\\rightarrowN). In other words,\nsplitting 'hole conjugated' type quasiparticles will lead to an energy loss and\ndecoherence, with energy carried away by neutral modes.",
        "positive": "Extrinsic-Intrinsic Crossover of the Spin Hall Effect Induced by\n  Alloying: We report the observation of the crossover between the extrinsic and\nintrinsic spin Hall effect induced by alloying. We found that the spin Hall\nangle, the ratio of the spin Hall conductivity to the electric conductivity,\nchanges drastically by tuning the composition of Au-Cu alloy. The spin Hall\nangle changes the sign only in a limited range of the Cu concentration due to\nthe extrinsic skew scattering, while the intrinsic contribution becomes\ndominant with increasing the Cu concentration. This observation provides\nessential information for fundamental understanding of spin-orbit physics."
    },
    {
        "anchor": "Colossal magnetic phase transition asymmetry in mesoscale FeRh stripes: Coupled order parameters in phase-transition materials can be controlled\nusing various driving forces such as temperature, magnetic and electric field,\nstrain, spin-polarized currents and optical pulses. Tuning the material\nproperties to achieve efficient transitions would enable fast and low-power\nelectronic devices. Here we show that the first-order metamagnetic phase\ntransition in FeRh films becomes strongly asymmetric in mesoscale structures.\nIn patterned FeRh stripes we observed pronounced supercooling and an\navalanche-like abrupt transition from the ferromagnetic to the\nantiferromagnetic phase while the reverse transition remains nearly continuous\nover a broad temperature range. Although modest asymmetry signatures have been\nfound in FeRh films, the effect is dramatically enhanced at the mesoscale. The\nasymmetry in the transitions is independent of applied magnetic fields and the\nactivation volume of the antiferromagnetic phase is more than two orders of\nmagnitude larger than typical magnetic heterogeneities observed in films. The\ncollective behavior upon cooling results from the role of long-range\nferromagnetic exchange correlations that become important at the mesoscale and\nshould be a general property of first-order magnetic phase transitions.",
        "positive": "Optical effects of spin currents in semiconductors: A spin current has novel linear and second-order nonlinear optical effects\ndue to its symmetry properties. With the symmetry analysis and the eight-band\nmicroscopic calculation we have systematically investigated the interaction\nbetween a spin current and a polarized light beam (or the \"photon spin\ncurrent\") in direct-gap semiconductors. This interaction is rooted in the\nintrinsic spin-orbit coupling in valence bands and does not rely on the Rashba\nor Dresselhaus effect. The light-spin current interaction results in an optical\nbirefringence effect of the spin current. The symmetry analysis indicates that\nin a semiconductor with inversion symmetry, the linear birefringence effect\nvanishes and only the circular birefringence effect exists. The circular\nbirefringence effect is similar to the Faraday rotation in magneto-optics but\ninvolves no net magnetization nor breaking the time-reversal symmetry.\nMoreover, a spin current can induce the second-order nonlinear optical\nprocesses due to the inversion-symmetry breaking. These findings form a basis\nof measuring a pure spin current where and when it flows with the standard\noptical spectroscopy, which may provide a toolbox to explore a wealth of\nphysics connecting the spintronics and photonics."
    },
    {
        "anchor": "Plasmon recombination in narrowgap HgTe quantum wells: The dispersion laws of two-dimensional plasmons in narrow-gap HgTe/CdHgTe\nquantum wells are calculated taking into account the spatial dispersion of the\nelectron susceptibility. At the energy scale of the band gap the dependence of\nplasmon frequencies on the wave vector is shown to be close to linear that\nchanges significantly the critical concentration of noneqilibrium electron-hole\ngas corresponding to \"switching-on\" the carrier recombination with plasmon\nemission. The recombination rates with the plasmon emission have been\ncalculated.",
        "positive": "Correlated electron-hole State in Twisted Double Bilayer Graphene: When twisted to angles near 1{\\deg}, graphene multilayers provide a new\nwindow on electron correlation physics by hosting gate-tuneable\nstrongly-correlated states, including insulators, superconductors, and unusual\nmagnets. Here we report the discovery of a new member of the family,\ndensity-wave states, in double bilayer graphene twisted to 2.37{\\deg}. At this\nangle the moir\\'e states retain much of their isolated bilayer character,\nallowing their bilayer projections to be separately controlled by gates. We use\nthis property to generate an energetic overlap between narrow isolated electron\nand hole bands with good nesting properties. Our measurements reveal the\nformation of ordered states with reconstructed Fermi surfaces, consistent with\ndensity-wave states, for equal electron and hole densities. These states can be\ntuned without introducing chemical dopants, thus opening the door to a new\nclass of fundamental studies of density-waves and their interplay with\nsuperconductivity and other types of order, a central issue in quantum matter\nphysics."
    },
    {
        "anchor": "Quantum state transfer of angular momentum via single electron\n  photo-excitation from a Zeeman-resolved light hole: Electron spins in GaAs quantum dots have been used to make qubits with\nhigh-fidelity gating and long coherence time, necessary ingredients in\nsolid-state quantum computing. The quantum dots can also host photon qubits\nwith energy applicable for optical communication, and can show a promising\nphoton-to-spin conversion. The coherent interface is established through\nphoto-excitation of a single pair of an electron and a Zeeman-resolved\nlight-hole, not heavy-hole. However, no experiments on the single photon to\nspin conversion have been performed yet. Here we report on single shot readout\nof a single electron spin generated in a GaAs quantum dot by spin-selective\nexcitation with linearly polarized light. A photo-electron spin generated from\na Zeeman-resolved light-hole exciton is detected using an optical spin blockade\nmethod in a single quantum dot and a Pauli spin blockade method in a double\nquantum dot. We found that the blockade probability strongly depends on the\nphoton polarization and the hole state, heavy- or light-hole, indicating a\ntransfer of the angular momentum from single photons to single electron spins.\nOur demonstration will open a pathway to further investigation on fundamental\nquantum physics such as quantum entanglement between a wide variety of quantum\nsystems and applications of quantum networking technology.",
        "positive": "Can tunneling current in molecular junctions be so strongly temperature\n  dependent to challenge a hopping mechanism? Analytical formulas answer this\n  question and provide important insight into large area junctions: {Analytical equations like Richardson-Dushman's or Shockley's provided a\ngeneral, if simplified conceptual background, which was widely accepted in\nconventional electronics and made a fundamental contribution to advances in the\nfield. In the attempt to develop a (highly desirable, but so far missing)\ncounterpart for molecular electronics, in this work, we deduce a general\nanalytical formula for the tunneling current through molecular junctions\nmediated by a single level that is valid for any bias voltage and temperature.\nStarting from this expression, which is exact and obviates cumbersome numerical\nintegration, in the low and high temperature limits we also provide analytical\nformulas expressing the current in terms of elementary functions. They are\naccurate for broad model parameter ranges relevant for real molecular\njunctions. Within this theoretical framework we show that: (i) by varying the\ntemperature, the tunneling current can vary by several orders of magnitude,\nthus debunking the myth that a strong temperature dependence of the current is\nevidence for a hopping mechanism, (ii) real molecular junctions can undergo a\ngradual (Sommerfeld-Arrhenius) transition from a weakly temperature dependent\nto a strongly (``exponential'') temperature dependent current that can be tuned\nby the applied bias, and (iii) important insight into large area molecular\njunctions with eutectic gallium indium alloy (EGaIn) top electrodes can be\ngained. E.g., merely based on transport data, we estimate that the current\ncarrying molecules represent only a fraction of f \\approx 4 \\times 10^{-4} out\nof the total number of molecules in a large area \\ce{Au-S-(CH2)13-CH_3 / EGaIn}\njunction."
    },
    {
        "anchor": "Conductance quantization in etched Si/SiGe quantum point contacts: We fabricated strongly confined Schottky-gated quantum point contacts by\netching Si/SiGe heterostructures and observed intriguing conductance\nquantization in units of approximately 1e2/h. Non-linear conductance\nmeasurements were performed depleting the quantum point contacts at fixed\nmode-energy separation. We report evidences of the formation of a half 1e2/h\nplateau, supporting the speculation that adiabatic transmission occurs through\n1D modes with complete removal of valley and spin degeneracies.",
        "positive": "Robust Two-Qubit Gates for Exchange-Coupled Qubits: We present composite pulse sequences that perform fault-tolerant two-qubit\ngate operations on exchange-only quantum dot spin qubits in various\nexperimentally relevant geometries. We show how to perform dynamically\ncorrected two-qubit gates in exchange-only systems with the leading hyperfine\nerror term cancelled. These pulse sequences are constructed to conform to the\nrealistic experimental constraint of strictly non-negative couplings. We\nestablish that our proposed pulse sequences lead to several orders of magnitude\nimprovement in the gate fidelity compared with their uncorrected counterparts.\nTogether with single-qubit dynamically corrected gates, our results enable\nnoise-resistant universal quantum operations with exchange-only qubits."
    },
    {
        "anchor": "Valley filtering and valley valves in irradiated pristine graphene: We theoretically study valley-filtering in pristine graphene irradiated by\nbicircular counter-rotating laser drive. The dynamical symmetry of the graphene\nand laser drive disrupts graphene's inversion symmetry, which results distinct\nquasi-energy states and Floquet band occupations in the two valleys.\nControlling the relative phase between the bicircular laser drive ultimately\nallows to blocks the contribution from one valley while allowing the opposite\nvalley currents in the system. For practical realization of valley-based\ndevice, we propose configurational setup for valley filters and valley valve\nconsisting of two graphene nanoribbons irradiated by two bicircular\ncounter-rotating laser drives with a relative phase shift. It is observed that\nthe relative phase between the two bicircular laser drives offer a control knob\nto generate valley-selective currents and transport responses with very high\nefficiency by an all-optical way. In addition, our findings about valley filter\nand valley valve are robust against moderate disorder and modest changes in\ndriving laser parameters. Present work opens an avenue to realise light-based\nvalleytronics devices in reality.",
        "positive": "Effects of an electron gas on the negative trion in semiconductor\n  quantum wells: We present here the results of calculations of the negative trion binding\nenergy in the presence of an electron gas. The screening of the Coulomb\ninteraction and the Pauli exclusion principle are considered. Our results show\na rapid ionization of the negative trion due to the Pauli exclusion principle\nwhile the screening is mainly responsible for the weakening of the trion\nbinding energy."
    },
    {
        "anchor": "Absence of signatures of Weyl orbits in the thickness dependence of\n  quantum transport in cadmium arsenide: In a Weyl orbit, the Fermi arc surface states on opposite surfaces of the\ntopological semimetal are connected through the bulk Weyl or Dirac nodes.\nHaving a real-space component, these orbits accumulate a sample-size-dependent\nphase. Following recent work on the three-dimensional Dirac semimetal cadmium\narsenide (Cd3As2), we have sought evidence for this thickness-dependent effect\nin quantum oscillations and quantum Hall plateaus in (112)-oriented Cd3As2 thin\nfilms grown by molecular beam epitaxy. We compare quantum transport in films of\nvarying thickness at apparently identical gate-tuned carrier concentrations and\nfind no clear dependence of the relative phase of the quantum oscillations on\nthe sample thickness. We show that small variations in carrier densities,\ndifficult to detect in low-field Hall measurements, lead to shifts in quantum\noscillations that are commensurate with previously reported phase shifts.\nFuture claims of Weyl orbits based on the thickness dependence of quantum\ntransport data require additional studies that demonstrate that these competing\neffects have been disentangled.",
        "positive": "Resonance fluorescence of a site-controlled quantum dot realized by the\n  buried-stressor growth technique: Site-controlled growth of semiconductor quantum dots (QDs) represents a major\nadvancement to achieve scalable quantum technology platforms. One immediate\nbenefit is the deterministic integration of quantum emitters into optical\nmicrocavities. However, site-controlled growth of QDs is usually achieved at\nthe cost of reduced optical quality. Here, we show that the buried-stressor\ngrowth technique enables the realization of high-quality site-controlled QDs\nwith attractive optical and quantum optical properties. This is evidenced by\nperforming excitation power dependent resonance fluorescence experiments at\ncryogenic temperatures showing QD emission linewidths down to 10 $\\mu$eV.\nResonant excitation leads to the observation of the Mollow triplet under CW\nexcitation and enables coherent state preparation under pulsed excitation.\nUnder resonant $\\pi$-pulse excitation we observe clean single photon emission\nassociated with $g^{(2)}(0)=0.12$ limited by non-ideal laser suppression."
    },
    {
        "anchor": "Valley hydrodynamics in gapped graphene: Recent experiments have revealed that novel nonequilibrium states consistent\nwith the hydrodynamic description of electrons are realized in ultrapure\ngraphene, which hosts the valley degrees of freedom. Here, we formulate a\ntheory of electron hydrodynamics including dissipation processes of the valley\nangular momentum by employing the concept of micropolar fluids. As a result,\nour theory proposes a novel strategy to generate a valley polarization by the\nmicrorotation. We uncover that the rotational viscosity induces longitudinal\nvalley currents which are second order in electric fields.",
        "positive": "Selective Manipulation and Tunneling Spectroscopy of Broken-Symmetry\n  Quantum Hall States in a Hybrid-edge Quantum Point Contact: We present a device architecture of hybrid-edge and dual-gated quantum point\ncontact. We demonstrate improved electrostatic control over the separation,\nposition, and coupling of each broken-symmetry compressible strip in graphene.\nVia low-temperature magneto-transport measurement, we demonstrate selective\nmanipulation over the evolution, hybridization, and transmission of arbitrarily\nchosen quantum Hall states in the channel. With gate-tunable tunneling\nspectroscopy, we characterize the energy gap of each symmetry-broken quantum\nHall state with high resolution on the order of ~0.1 meV."
    },
    {
        "anchor": "Momentum resolved ground/excited states and the ultra-fast excited state\n  dynamics of monolayer MoS2: The emergence of transition metal dichalcogenides (TMD) as crystalline\natomically thin semiconductors has created a tremendous amount of scientific\nand technological interest. Many novel device concepts have been proposed and\nrealized (1-3). Nonetheless, progress in k-space investigations of\nground/excited state electronic structures has been slow due to the challenge\nto create large scale, laterally homogeneous samples. Taking advantage of\nrecent advancements in chemical vapor deposition, here we create a wafer-size\nMoS2 monolayer with well-aligned lateral orientation for advanced electron\nspectroscopy studies (4-6). Low energy electron diffraction and scanning\ntunneling microscopy (STM) demonstrate atomically clean surfaces with in-plane\ncrystalline orientation. The ground state and excited state electronic\nstructures are probed using scanning tunneling spectroscopy (STS),\nangle-resolved photoemission (ARPES) and time-resolved (tr-)ARPES. In addition\nto mapping out the momentum-space quasiparticle band structure in the valence\nand conduction bands, we unveil ultrafast excited state dynamics, including\ninter- and intra-valley carrier scattering and a rapid downward energy shift by\n~ 0.2eV lower than the initial free carrier state at Sigma point.",
        "positive": "The role of the strain induced population imbalance in Valley\n  polarization of graphene: Berry curvature perspective: Real magnetic and lattice deformation gauge fields have been investigated in\nhoneycomb lattice of graphene. The coexistence of these two gauges will induce\na gap difference between two valley points ($K$ and $K'$) of system. This gap\ndifference allows us to study the possible topological valley Hall current and\nvalley polarization in the graphene sheet. In the absence of magnetic field,\nthe strain alone could not generate a valley polarization when the Fermi energy\ncoincides exactly with the Dirac points. Since in this case there is not any\nimbalance between the population of the valley points. In other words each of\nthese gauges alone could not induce any topological valley-polarized current in\nthe system at zero Fermi energy. Meanwhile at non-zero Fermi energies\npopulation imbalance can be generated as a result of the external strain even\nat zero magnetic field. In the context of Berry curvature within the linear\nresponse regime the valley polarization (both magnetic free polarization,\n$\\Pi_0$, and field dependent response function, $\\chi_\\alpha$) in different\nvalues of gauge fields of lattice deformation has been obtained."
    },
    {
        "anchor": "Colossal stability of antiferromagnetically exchange coupled nanomagnets: Bistable nanomagnets store a binary bit of information. Exchange coupled\nnanomagnets can increase the thermal stability at low dimensions. Here we show\nthat the antiferromagnetically (AFM) coupled nanomagnets can be highly stable\nat low dimensions than that of the ferromagnetically (FM) coupled nanomagnets.\nBy solving stochastic Landau-Lifshitz-Gilbert equation of magnetization\ndynamics at room temperature, we analyze the stability of the exchange coupled\nnanomagnets in the presence of correlated, uncorrelated, and anti-correlated\nnoise. The results show that the correlated noise can make the stability of the\nAFM coupled nanomagnets very high. Such finding will lead to very high-density\nnon-volatile storage and logic devices in our future information processing\nsystems.",
        "positive": "Thermal conductance at the interface between crystals using equilibrium\n  and non-equilibrium molecular dynamics: In this article, we compare the results of non-equilibrium (NEMD) and\nequilibrium (EMD) molecular dynamics methods to compute the thermal conductance\nat the interface between solids. We propose to probe the thermal conductance\nusing equilibrium simulations measuring the decay of the thermally induced\nenergy fluctuations of each solid. We also show that NEMD and EMD give\ngenerally speaking inconsistent results for the thermal conductance: Green Kubo\nsimulations probe the Landauer conductance between two solids which assumes\nphonons on both sides of the interface to be at equilibrium. On the other hand,\nwe show that NEMD give access to the out-of-equilibrium interfacial conductance\nconsistent with the interfacial flux describing phonon transport in each solid.\nThe difference may be large and reaches typically a factor 5 for interfaces\nbetween usual semi-conductors. We analyze finite size effects for the two\ndeterminations of the interfacial thermal conductance, and show that the\nequilibrium simulations suffer from severe size effects as compared to NEMD. We\nalso compare the predictions of the two above mentioned methods -EMD and NEMD-\nregarding the interfacial conductance of a series of mass mismatched\nLennard-Jones solids. We show that the Kapitza conductance obtained with EMD\ncan be well described using the classical diffuse mismatch model (DMM). On the\nother hand, NEMD simulations results are consistent with a out-of-equilibrium\ngeneralisation of the acoustic mismatch model (AMM). These considerations are\nimportant in rationalizing previous results obtained using molecular dynamics,\nand help in pinpointing the physical scattering mechanisms taking place at\natomically perfect interfaces between solids, which is a prerequesite to\nunderstand interfacial heat transfer across real interfaces."
    },
    {
        "anchor": "Observation of a cyclotron harmonic spike in microwave-induced\n  resistances in ultraclean GaAs/AlGaAs quantum wells: We report the observation of a colossal, narrow resistance peak that arises\nin ultraclean (mobility 3X10^7cm^2/Vs) GaAs/AlGaAs quantum wells (QWs) under\nmillimeterwave irradiation and a weak magnetic field. Such a spike is\nsuperposed on the 2nd harmonic microwave-induced resistance oscillations (MIRO)\nbut having an amplitude > 300% of the MIRO, and a typical FWHM ~50 mK,\ncomparable with the Landau level width. Systematic studies show a correlation\nbetween the spike and a pronounced negative magnetoresistance in these QWs,\nsuggesting a mechanism based on the interplay of strong scatterers and smooth\ndisorder. Alternatively, the spike may be interpreted as a manifestation of\nquantum interference between the quadrupole resonance and the higher-order\ncyclotron transition in well-separated Landau levels.",
        "positive": "Extremely long quasiparticle spin lifetimes in superconducting aluminium\n  using MgO tunnel spin injectors: There has been an intense search in recent years for long-lived\nspin-polarized carriers for spintronic and quantum-computing devices. Here we\nreport that spin polarized quasi-particles in superconducting aluminum layers\nhave surprisingly long spin-lifetimes, nearly a million times longer than in\ntheir normal state. The lifetime is determined from the suppression of the\naluminum's superconductivity resulting from the accumulation of spin polarized\ncarriers in the aluminum layer using tunnel spin injectors. A Hanle effect,\nobserved in the presence of small in-plane orthogonal fields, is shown to be\nquantitatively consistent with the presence of long-lived spin polarized\nquasi-particles. Our experiments show that the superconducting state can be\nsignificantly modified by small electric currents, much smaller than the\ncritical current, which is potentially useful for devices involving\nsuperconducting qubits."
    },
    {
        "anchor": "Two-dimensional flexible high diffusive spin circuits: Owing to their unprecedented electronic properties, graphene and\ntwo-dimensional (2D) crystals have brought fresh opportunities for advances in\nplanar spintronic devices. Graphene is an ideal medium for spin transport while\nalso being an exceptionally resilient material for flexible electronics.\nHowever, these extraordinary traits have never been combined to create flexible\ngraphene spin circuits. Realizing such circuits could lead to bendable\nstrain-based spin sensors, a unique platform to explore pure spin current based\noperations and low power flexible nanoelectronics. Here, we demonstrate\ngraphene spin circuits on flexible substrates for the first time. These\ncircuits, realized using chemical vapour deposited (CVD) graphene, exhibit\nlarge spin diffusion coefficients ~0.19-0.24 m2s-1 at room temperature.\nCompared to conventional devices of graphene on Si/SiO2 substrates, such values\nare 10-20 times larger and result in a maximum spin diffusion length ~10 um in\ngraphene achieved on such industry standard substrates, showing one order\nenhanced room temperature non-local spin signals. These devices exhibit state\nof the art spin diffusion, arising out of a distinct substrate topography that\nfacilitates efficient spin transport, leading to a scalable, high-performance\nplatform towards flexible 2D spintronics. Our innovation unlocks a new domain\nfor the exploration of strain-dependent spin phenomena and paves the way for\nflexible graphene spin memory-logic units and surface mountable sensors.",
        "positive": "Resonant Raman scattering off neutral quantum dots: Resonant inelastic (Raman) light scattering off neutral GaAs quantum dots\nwhich contain a mean number, N=42, of electron-hole pairs is computed. We find\nRaman amplitudes corresponding to strongly collective final states\n(charge-density excitations) of similar magnitude as the amplitudes related to\nweakly collective or single-particle excitations. As a function of the incident\nlaser frequency or the magnetic field, they are rapidly varying amplitudes. It\nis argued that strong Raman peaks should come out in the spin-density channels,\nnot related to valence-band mixing effects in the intermediate states."
    },
    {
        "anchor": "Heat dissipation in few-layer MoS2 and MoS2/hBN heterostructure: State-of-the-art fabrication and characterization techniques have been\nemployed to measure the thermal conductivity of suspended, single-crystalline\nMoS2 and MoS2/hBN heterostructures. Two-laser Raman scattering thermometry was\nused combined with real time measurements of the absorbed laser power, which\nallowed us to determine the thermal conductivities without any assumptions.\nMeasurements on MoS2 layers with thicknesses of 5 and 14 exhibit thermal\nconductivity in the range between 12 and 24 Wm-1K-1. Additionally, after\ndetermining the thermal conductivity of a selected MoS2 sample, an hBN flake\nwas transferred onto it and the effective thermal conductivity of the\nheterostructure was subsequently measured. Remarkably, despite that the\nthickness of the hBN layer was less than a third of the thickness of the MoS2\nlayer, the heterostructure showed an almost eight-fold increase in the thermal\nconductivity, being able to dissipate more than 10 times the laser power\nwithout any visible sign of damage. These results are consistent with a high\nthermal interface conductance between MoS2 and hBN and an efficient in-plane\nheat spreading driven by hBN. Indeed, we estimate G 70 MWm-2K-1 which is\nsignificantly higher than previously reported values. Our work therefore\ndemonstrates that the insertion of hBN layers in potential MoS2 based devices\nholds the promise for efficient thermal management.",
        "positive": "Topological defects and Goldstone excitations in domain walls between\n  ferromagnetic quantum Hall effect liquids: It is shown that the low-energy spectrum of a ferromagnetic quantum Hall\neffect liquid in a system with a multi-domain structure generated by an\ninhomogeneous bare Zeeman splitting $\\epsilon_{Z}$ is formed by excitations\nlocalized at the walls between domains. For a step-like $\\epsilon_Z(r)$, the\ndomain wall spectrum includes a spin-wave with a linear dispersion and a small\ngap due to spin-orbit coupling, and a low-energy topological defects. The\nlatter are charged and may dominate in the transport under conditions that the\npercolation through the network of domain walls is provided."
    },
    {
        "anchor": "Observation of Zeeman effect in topological surface state with distinct\n  material dependence: The helical Dirac fermions on the surface of topological insulators host\nnovel relativistic quantum phenomena in solids. Manipulating spins of\ntopological surface state (TSS) represents an essential step towards exploring\nthe theoretically predicted exotic states related to time reversal symmetry\n(TRS) breaking via magnetism or magnetic field. Understanding Zeeman effect of\nTSS and determining its g-factor are pivotal for such manipulations in the\nlatter form of TRS breaking. Here, we report those direct experimental\nobservations in Bi2Se3 and Sb2Te2Se by spectroscopic imaging scanning tunneling\nmicroscopy. The Zeeman shifting of zero mode Landau level is identified\nunambiguously by judiciously excluding the extrinsic influences associated with\nthe non-linearity in the TSS band dispersion and the spatially varying\npotential. The g-factors of TSS in Bi2Se3 and Sb2Te2Se are determined to be 18\nand -6, respectively. This remarkable material dependence opens a new route to\ncontrol the spins in the TSS.",
        "positive": "Quasi-bound states of quantum dots in single and bilayer graphene: Dirac fermions interacting with a cylindrically symmetric quantum dot\npotential created in single and bilayer graphene are not confined but form\nquasi-bound states. The broadening of these quasi-bound states (i. e. the\ninverse of their lifetimes) decreases (increases) with the orbital momentum of\nthe electron in the case of graphene (bilayer). Quasi-bound states with energy\nbelow (above) the barrier height are dominantly electron(hole)-like. A\nremarkable decrease of the energy level broadening is predicted for electron\nenergies close to the barrier height, which are a consequence of the total\ninternal reflection of the electronic wave at the dot edge."
    },
    {
        "anchor": "Beyond no-go theorem' Weyl phonons: By using \\emph{ab initio} calculations and symmetry analysis, we define a new\nclass of Weyl phonons, i.e., isolated Weyl phonons (IWPs), which are\ncharacterized by Chern number $\\pm$2 or $\\pm$4 in their acoustic phononic\nspectra and protected by the time inversion symmetry and point group\nsymmetries. More importantly, their particular topological feature make them\ncircumvent from the no-go theorem. Some high-symmetry points, behaving as\nisolated Weyl points in the space groups (SGs) of the related phononic systems,\ntend to form IWPs. As enumerated in Table I, the IWPs are located at the center\nof three-dimensional Brillouin zone (BZ), and protected by the time-reversal\nsymmetry ($\\cal T$) and the corresponding point group symmetries. Moreover, a\nrealistic chiral crystal material example of K$_2$Mg$_2$O$_3$ in SG 96, a\nmonopole IWP with Chern number -2 is found at the high-symmetry point $\\Gamma$,\nand in another material example of Nb$_3$Al$_2$N in SG 213, a monopole IWP with\nChern number +4 is confirmed at the point $\\Gamma$. It is interesting that that\nIWPs can not form the surface arcs in the surface BZ, which has not been\nreported in the phononic systems to present. Our theoretical results not only\nuncover a new class of Weyl phonons (IWPs), but also put forwards an effective\nway to search the IWPs in spinless systems.",
        "positive": "Temperature Dependent Photophysics of Single NV Centers in Diamond: We present a comprehensive study of the temperature and magnetic-field\ndependent photoluminescence (PL) of individual NV centers in diamond, spanning\nthe temperature-range from cryogenic to ambient conditions. We directly observe\nthe emergence of the NV's room-temperature effective excited state structure\nand provide a clear explanation for a previously poorly understood broad\nquenching of NV PL at intermediate temperatures around 50 K. We develop a model\nthat quantitatively explains all of our findings, including the strong impact\nthat strain has on the temperaturedependence of the NV's PL. These results\ncomplete our understanding of orbital averaging in the NV excited state and\nhave significant implications for the fundamental understanding of the NV\ncenter and its applications in quantum sensing."
    },
    {
        "anchor": "Andreev Conductance of Chaotic and Integrable Quantum Dots: We examine the voltage V and magnetic field B dependent Andreev conductance\nof a chaotic quantum dot coupled via point contacts to a normal metal and a\nsuperconductor. In the case where the contact to the superconductor dominates,\nwe find that the conductance is consistent with the dot itself behaving as a\nsuperconductor-- it appears as though Andreev reflections are occurring locally\nat the interface between the normal lead and the dot. This is contrasted\nagainst the behaviour of an integrable dot, where for a similar strong coupling\nto the superconductor, no such effect is seen. The voltage dependence of the\nAndreev conductance thus provides an extremely pronounced quantum signature of\nthe nature of the dot's classical dynamics. For the chaotic dot, we also study\nnon-monotonic re-entrance effects which occur in both V and B.",
        "positive": "Wavefunctions and counting formulas for quasiholes of clustered quantum\n  Hall states on a sphere: The quasiholes of the Read-Rezayi clustered quantum Hall states are\nconsidered, for any number of particles and quasiholes on a sphere, and for any\ndegree k of clustering. A set of trial wavefunctions, that are zero-energy\neigenstates of a k+1-body interaction, and so are symmetric polynomials that\nvanish when any k+1 particle coordinates are equal, is obtained explicitly and\nproved to be both complete and linearly independent. Formulas for the number of\nstates are obtained, without the use of (but in agreement with) conformal field\ntheory, and extended to give the number of states for each angular momentum. An\ninteresting recursive structure emerges in the states that relates those for k\nto those for k-1. It is pointed out that the same numbers of zero-energy states\ncan be proved to occur in certain one-dimensional models that have recently\nbeen obtained as limits of the two-dimensional k+1-body interaction\nHamiltonians, using results from the combinatorial literature."
    },
    {
        "anchor": "Anapoles in Free-Standing III-V Nanodisks Enhancing Second-Harmonic\n  Generation: Nonradiating electromagnetic configurations in nanostructures open new\nhorizons for applications due to two essential features: lack of energy losses\nand invisibility to the propagating electromagnetic field. Such radiationless\nconfigurations form a basis for new types of nanophotonic devices, where a\nstrong electromagnetic field confinement can be achieved together with lossless\ninteractions between nearby components. In our work, we present a new design of\nfree-standing disk nanoantennas with nonradiating current distributions for the\noptical near-infrared range. We show a novel approach to create nanoantennas by\nslicing III-V nanowires into standing disks using focused ion beam milling. We\nexperimentally demonstrate the suppression of the far-field radiation and the\nassociated strong enhancement of the second-harmonic generation from the disk\nnanoantennas. With a theoretical analysis of the electromagnetic field\ndistribution using multipole expansions in both spherical and Cartesian\ncoordinates, we confirm that the demonstrated nonradiating configurations are\nanapoles. We expect that the presented procedure to design and produce disk\nnanoantennas from nanowires become one of standard approaches to fabricate\ncontrolled chains of standing nanodisks with different designs and\nconfigurations. These chains can be an essential building blocks for new types\nof lasers and sensors with low power consumption.",
        "positive": "Atomistic transport modeling, design principles and empirical rules for\n  Low Noise III-V Digital Alloy Avalanche Photodiodes: A series of III-V ternary and quarternary digital alloy avalanche photodiodes\n(APDs) have recently been seen to exhibit very low excess noise. Using band\ninversion of an environment-dependent atomistic tight binding description of\nshort period superlattices, we argue that a combination of increased effective\nmass, minigaps and band split-off are primarily responsible for the observed\nsuperior performance. These properties significantly limit the ionization rate\nof one carrier type, either holes or electrons, making the avalanche\nmultiplication process unipolar in nature. The unipolar behavior in turn\nreduces the stochasticity of the multiplication gain. The effects of band\nfolding on carrier transport are studied using the Non-Equilibrium Green's\nFunction Method that accounts for quantum tunneling, and Boltzmann Transport\nEquation model for scattering. It is shown here that carrier transport by\nintraband tunneling and optical phonon scattering are reduced in materials with\nlow excess noise. Based on our calculations, we propose five simple\ninequalities that can be used to approximately evaluate the suitability of\ndigital alloys for designing low noise photodetectors. We evaluate the\nperformance of multiple digital alloys using these criteria and demonstrate\ntheir validity."
    },
    {
        "anchor": "Realization of One-Way Electromagnetic Modes at the Interface Between\n  Two Dissimilar Metals: We calculate the dispersion relations for electromagnetic waves propagating\nat the interface between two dissimilar Drude metals in an external magnetic\nfield B parallel to the interface. The propagating modes are bound to the\ninteface and travel perpendicular to B. In certain frequency ranges, the waves\ncan propagate in one direction only. The frequency range for these one-way\nmodes increases with increasing B. One group of modes occurs at moderate\nfrequencies, between the lower and upper plasma frequencies of the two metals.\nThe other occurs at much lower frequencies, between their lower and upper\ncyclotron frequencies. We discuss possible ways to realize such modes in real\nmaterials, including dissimilar superconductors.",
        "positive": "Armchair graphene nanoribbons: Electronic structure and electric field\n  modulation: We report electronic structure and electric field modulation calculations in\nthe width direction for armchair graphene nanoribbons (acGNRs) using a\nsemi-empirical extended Huckel theory. Important band structure parameters are\ncomputed, e.g. effectives masses, velocities and bandgaps. For the three types\nof acGNRs, the pz orbital tight-binding parameters are extracted if feasible.\nFurthermore, the effect of electric field in the width direction on acGNRs\ndispersion is explored. It is shown that for the two types of semiconducting\nacGNRs, an external electric field can reduce the bandgap to a few meV with\ndifferent quantitative behavior."
    },
    {
        "anchor": "Thermal Desorption of Hydrogen From Graphene: The process of hydrogen desorption from graphane (graphene sheet saturated by\nhydrogen adsorbed from both sides) has been studied using the method of\nmolecular dynamics. The temperature dependences of the time of desorption onset\nfor various hydrogen coverages on graphene are calculated and the corresponding\nactivation energies in the Arrhenius equation are determined. It is established\nthat graphane exhibits a rather high thermal stability that makes possible its\nusein two-dimensional electronics even at room temperature. For the same\nreason, graphane can hardly be considered as a promising hydrogen storage\nmaterial for fuel cells.",
        "positive": "Optimization of photon correlations by frequency filtering: Photon correlations are a cornerstone of Quantum Optics. Recent works [NJP 15\n025019, 033036 (2013), PRA 90 052111 (2014)] have shown that by keeping track\nof the frequency of the photons, rich landscapes of correlations are revealed.\nStronger correlations are usually found where the system emission is weak.\nHere, we characterize both the strength and signal of such correlations,\nthrough the introduction of the 'frequency resolved Mandel parameter'. We study\na plethora of nonlinear quantum systems, showing how one can substantially\noptimize correlations by combining parameters such as pumping, filtering\nwindows and time delay."
    },
    {
        "anchor": "Successes and Failures of Kadanoff-Baym Dynamics in Hubbard Nanoclusters: We study the non-equilibrium dynamics of small, strongly correlated clusters,\ndescribed by a Hubbard Hamiltonian, by propagating in time the Kadanoff-Baym\nequations within the Hartree-Fock, 2nd Born, GW and T-matrix approximations. We\ncompare the results to exact numerical solutions. We find that the T-matrix is\noverall superior to the other approximations, and is in good agreement with the\nexact results in the low-density regime. In the long time limit, the many-body\napproximations attain an unphysical steady state which we attribute to the\nimplicit inclusion of infinite order diagrams in a few-body system.",
        "positive": "Ultrafast carrier relaxation in GaN, In_(0.05)Ga_(0.95)N and an\n  In_(0.05)Ga_(0.95)/In_(0.15)Ga_(0.85)N Multiple Quantum Well: Room temperature, wavelength non-degenerate ultrafast pump/probe measurements\nwere performed on GaN and InGaN epilayers and an InGaN multiple quantum well\nstructure. Carrier relaxation dynamics were investigated as a function of\nexcitation wavelength and intensity. Spectrally-resolved sub-picosecond\nrelaxation due to carrier redistribution and QW capture was found to depend\nsensitively on the wavelength of pump excitation. Moreover, for pump\nintensities above a threshold of 100 microJ/cm2, all samples demonstrated an\nadditional emission feature arising from stimulated emission (SE). SE is\nevidenced as accelerated relaxation (< 10 ps) in the pump-probe data,\nfundamentally altering the re-distribution of carriers. Once SE and carrier\nredistribution is completed, a slower relaxation of up to 1 ns for GaN and\nInGaN epilayers, and 660 ps for the MQW sample, indicates carrier recombination\nthrough spontaneous emission."
    },
    {
        "anchor": "Deposition of defected graphene on (001) Si substrates by thermal\n  decomposition of acetone: We present results on the deposition and characterization of defected\ngraphene by the chemical vapor deposition (CVD) method. The source of\ncarbon/carbon-containing radicals is thermally decomposed acetone (C2H6CO) in\nAr main gas flow. The deposition takes place on (001) Si substrates at about\n1150-11600C. We established by Raman spectroscopy the presence of single- to\nfew- layered defected graphene deposited on two types of interlayers that\npossess different surface morphology and consisted of mixed sp2 and sp3\nhybridized carbon. The study of interlayers by XPS, XRD, GIXRD and SEM\nidentifies different phase composition: i) a diamond-like carbon dominated film\nconsisting some residual SiC, SiO2 etc.; ii) a sp2- dominated film consisting\nsmall quantities of C60/C70 fullerenes and residual Si-O-, C=O etc. species.\nThe polarized Raman studies confirm the presence of many single-layered\ndefected graphene areas that are larger than few microns in size on the\npredominantly amorphous carbon interlayers.",
        "positive": "Gate controlled quantum interference: direct observation of\n  anti-resonances in single molecule charge transport: Quantum interference can profoundly affect charge transport in single\nmolecules, but experiments can usually measure only the conductance at the\nFermi energy. Because in general the most pronounced features of the quantum\ninterference are not located at the Fermi energy, it is highly desirable to\nprobe charge transport in a broader energy range. Here by the method of\nelectrochemical gating, we measure the conductance and map the transmission\nfunctions of single molecules at and around the Fermi energy, and study\nsignatures associated with constructive and destructive interference. With the\nelectrochemical gate control, we tune the quantum interference between the\nhighest occupied molecular orbital (HOMO) and lowest unoccupied molecular\norbital (LUMO), and directly observe anti-resonance, a distinct feature of\ndestructive interference. By tuning the molecule in and out of anti-resonance,\nwe achieve continuous control of the conductance over 2 orders of magnitude\nwith a subthreshold swing of ~17 mV/dec, features relevant to high-speed and\nlow-power electronics."
    },
    {
        "anchor": "Towards superlattices: Lateral bipolar multibarriers in graphene: We report on transport properties of monolayer graphene with a laterally\nmodulated potential profile, employing striped top gate electrodes with\nspacings of 100 nm to 200 nm. Tuning of top and back gate voltages gives rise\nto local charge carrier density disparities, enabling the investigation of\ntransport properties either in the unipolar (nn') or the bipolar (np') regime.\nIn the latter pronounced single- and multibarrier Fabry-Perot (FP) resonances\noccur. We present measurements of different devices with different numbers of\ntop gate stripes and spacings. The data are highly consistent with a phase\ncoherent ballistic tight binding calculation and quantum capacitance model,\nwhereas a superlattice effect and modification of band structure can be\nexcluded.",
        "positive": "Soft Carrier Multiplications by Hot Electrons in Graphene: By using Boltzmann formalism, we show that carrier multiplication by impact\nionization can take place at relatively low electric fields during electronic\ntransport in graphene. Because of the absence of energy gap, this effect is not\ncharacterized by a field threshold unlike in conventional semiconductors, but\nis a quadratic function of the electric field. We also show that the resulting\ncurrent is an increasing function of the electronic temperature, but decreases\nwith increasing carrier concentration."
    },
    {
        "anchor": "Nonpolar m-plane GaN/AlGaN heterostructures with intersubband\n  transitions in the 5 to 10 THz band: This paper assesses intersubband transitions in the 1 to 10 THz frequency\nrange in nonpolar m-plane GaN/AlGaN multi-quantum-wells deposited on\nfree-standing semi-insulating GaN substrates. The quantum wells were designed\nto contain two confined electronic levels, decoupled from the neighboring\nwells. Structural analysis reveals flat and regular quantum wells in the two\nperpendicular inplane directions, with high-resolution images showing\ninhomogeneities of the Al composition in the barriers along the growth axis. We\ndo not observe extended structural defects introduced by the epitaxial process.\nLow-temperature intersubband absorption from 1.5 to 9 THz is demonstrated,\ncovering part of the 7 to 10 THz band forbidden to GaAs-based technologies.",
        "positive": "Valley-isospin dependence of the quantum Hall effect in a graphene p-n\n  junction: We calculate the conductance G of a bipolar junction in a graphene\nnanoribbon, in the high-magnetic field regime where the Hall conductance in the\np-doped and n-doped regions is 2e^2/h. In the absence of intervalley\nscattering, the result G=(e^2/h)(1-cos Phi) depends only on the angle Phi\nbetween the valley isospins (= Bloch vectors representing the spinor of the\nvalley polarization) at the two opposite edges. This plateau in the conductance\nversus Fermi energy is insensitive to electrostatic disorder, while it is\ndestabilized by the dispersionless edge state which may exist at a zigzag\nboundary. A strain-induced vector potential shifts the conductance plateau up\nor down by rotating the valley isospin."
    },
    {
        "anchor": "Reversible optical doping of graphene: The ultimate surface exposure provided by graphene monolayer makes it the\nideal sensor platform but also exposes its intrinsic properties to any\nenvironmental perturbations. In this work, we demonstrate that the charge\ncarrier density of graphene exfoliated on a SiO$_2$/Si substrate can be finely\nand reversibly tuned between electron and hole doping with visible photons.\nThis photo-induced doping happens under moderate laser power conditions but is\nsignificantly affected by the substrate cleaning method. In particular, it is\nfound to require hydrophilic substrates and to vanish in suspended graphene.\nThese findings suggest that optically gated graphene devices operating with a\nsub-second time scale can be envisioned but also that Raman spectroscopy is not\nalways as non-invasive as generally assumed.",
        "positive": "Controlling Band Gap in Silicene Monolayer Using External Electric Field: We study the geometric and electronic structures of silicene monolayer using\ndensity functional theory based calculations. The electronic structures of\nsilicene show that it is a semi-metal and the charge carriers in silicene\nbehave like massless Dirac-Fermions since it possesses linear dispersion around\nDirac point. Our results show that the band gap in silicene monolayer can be\nopened up at Fermi level due to an external electric field by breaking the\ninversion symmetry. The presence of buckling in geometric structure of silicene\nplays an important role in breaking the inversion symmetry. We also show that\nthe band gap varies linearly with the strength of external electric field.\nFurther, the value of band gap can be tuned over a wide range."
    },
    {
        "anchor": "Theory of Macroscopic Quantum Dynamics in High-Tc Josephson Junctions: We have theoretically investigated macroscopic quantum tunneling (MQT) and\nthe influence of nodal quasiparticles and zero energy bound states (ZES) on MQT\nin s-wave/d-wave hybrid Josephson junctions. In contrast to d-wave/d-wave\njunctions, the low-energy quasiparticle dissipation resulting from nodal\nquasiparticles and ZES is suppressed due to a quasiparticle-tunneling blockade\neffect in an isotropic s-wave superconductor. Therefore, the inherent\ndissipation in these junctions is found to be weak. This result suggests high\npotential of s-wave/d-wave hybrid junctions for applications in quantum\ninformation devices.",
        "positive": "Theory of valley-dependent transport in graphene-based lateral quantum\n  structures: Modulation of electronic states in two-dimensional (2D) materials can be\nachieved by using in-plane variations of the band gap or the average potential\nin lateral quantum structures. In the atomic configurations with hexagonal\nsymmetry, this approach makes it possible to tailor the valleytronic properties\nfor potential device applications. In this work, we present a multi-band theory\nto calculate the valley-dependent electron transport in graphene-based lateral\nquantum structures. As an example, we consider the structures with a single\ninterface that exhibits an energy gap or potential discontinuity. The\ntheoretical formalism proceeds within the tight-binding description, by first\nderiving the local bulk complex band structures in the regions of a constant\ngap or potential and, next, joining the local wave functions across the\ninterface via a cell-averaged current operator to ensure the current\ncontinuity. The theory is applied to the study of electron reflection off and\ntransmission through an interface. Both reflection and transmission are found\nto exhibit valley-contrast behavior that can be used to generate\nvalley-polarized electron sources. The results vary with the type of\ninterfaces, as well as between monolayer and bilayer graphene based structures.\nIn the monolayer case, the valley contrast originates from the band warping and\nonly becomes sizable for incident carriers of high energy; whereas in\nAB-stacked bilayer graphene, the vertical interlayer coupling emerges as an\nadditional important cause for valley contrast, and the favorable carrier\nenergy is also found to be drastically lower. Our numerical results clearly\ndemonstrate the propitious valleytronic properties of bilayer graphene\nstructures."
    },
    {
        "anchor": "The prolonged decay of RKKY interactions by interplay of relativistic\n  and non-relativistic electrons in semi-Dirac semimetals: The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction has been extensively\nexplored in isotropic Dirac systems with linear dispersion, which typically\nfollows an exponent decaying rate with the impurity distance $R$, i.e.,\n$J\\propto 1/R^d$ ($1/R^{2d-1}$) in $d$-dimensional systems at finite (zero)\nFermi energy. This fast decay makes it rather difficult to be detected and\nlimits its application in spintronics. Here, we theoretically investigate the\ninfluence of anisotropic dispersion on the RKKY interaction, and find that the\nintroduction of non-relativistic dispersion in semi-Dirac semimetals (S-DSMs)\ncan significantly prolong the decay of the RKKY interaction and can remarkably\nenhance the Dzyaloshinskii-Moriya interaction around the relativistic\ndirection. The underlying physics is attributed to the highly increased density\nof states in the linear-momentum direction as a result of the interplay of\nrelativistic and non-relativistic electrons. Furthermore, we propose a general\nformula to determine the decaying rate of the RKKY interaction, extending the\ntypical formula for isotropic DSMs. Our results suggest that the S-DSM\nmaterials are a powerful platform to detect and control the magnetic exchange\ninteraction, superior to extensively adopted isotropic Dirac systems.",
        "positive": "Integrated high frequency aluminum nitride optomechanical resonators: Aluminum nitride (AlN) has been widely used in microeletromechanical\nresonators for its excellent electromechanical properties. Here we demonstrate\nthe use of AlN as an optomechanical material that simultaneously offer low\noptical and mechanical loss. Integrated AlN microring resonators in the shape\nof suspended rings exhibit high optical quality factor (Q) with loaded Q up to\n125,000. Optomechanical transduction of the Brownian motion of a GHz contour\nmode yields a displacement sensitivity of 6.2\\times10^(-18)m/Hz^(1/2) in\nambient air."
    },
    {
        "anchor": "Opening-Assisted Coherent Transport in the Deep Classical Regime: We study quantum enhancement of transport in open systems in the presence of\ndisorder and dephasing. Quantum coherence effects may significantly enhance\ntransport in open systems even in the deep classical regime (where the\ndecoherence rate is greater than the inter-site hopping amplitude), as long as\nthe disorder is sufficiently strong. When the strengths of disorder and\ndephasing are fixed, there is an optimal opening strength at which the coherent\ntransport enhancement is optimized. Analytic results are obtained in two simple\nparadigmatic tight-binding models of large systems: the linear chain and the\nfully connected network. The physical behavior is also reflected in the FMO\nphotosynthetic complex, which may be viewed as intermediate between these\nparadigmatic models.",
        "positive": "Range dependence of interlayer exchange coupling: We have considered the effects of non magnetic impurities and interface\nroughness on the interlayer coupling between magnetic layers in metallic\nmultilayers. The two types of defects alter the interlayer coupling in quite\ndifferent ways. Elastic electron scattering by impurities in the non magnetic\nspacer layers between magnetic layers produces an exponential decay of the\ncoupling with a characteristic decay length that is considerably longer than\nthe ``global'' transport mean free path for the spacer layer with its\nsurrounding interfaces. Interfacial roughness leads to an attenuation of the\ncoupling that is related to the width of the roughness in relation to the Fermi\nwavelength; roughness does not alter the range dependence of the coupling. For\ncertain types of electrical transport, e.g., for current perpendicular to the\nplane of the layers, the scattering from interface roughness and impurities in\nthe spacer layers contribute on an equal footing to the exponential decay of\nthe electron propagators, i.e., global mean free path. We show that interface\nroughness and impurities in the spacer layer affect the interlayer coupling\ndifferently."
    },
    {
        "anchor": "Compactly-supported Wannier functions and algebraic $K$-theory: In a tight-binding lattice model with $n$ orbitals (single-particle states)\nper site, Wannier functions are $n$-component vector functions of position that\nfall off rapidly away from some location, and such that a set of them in some\nsense span all states in a given energy band or set of bands;\ncompactly-supported Wannier functions are such functions that vanish outside a\nbounded region. They arise not only in band theory, but also in connection with\ntensor-network states for non-interacting fermion systems, and for flat-band\nHamiltonians with strictly short-range hopping matrix elements. In earlier\nwork, it was proved that for general complex band structures (vector bundles)\nor general complex Hamiltonians---that is, class A in the ten-fold\nclassification of Hamiltonians and band structures---a set of\ncompactly-supported Wannier functions can span the vector bundle only if the\nbundle is topologically trivial, in any dimension $d$ of space, even when use\nof an overcomplete set of such functions is permitted. This implied that, for a\nfree-fermion tensor network state with a non-trivial bundle in class A, any\nstrictly short-range parent Hamiltonian must be gapless. Here, this result is\nextended to all ten symmetry classes of band structures without additional\ncrystallographic symmetries, with the result that in general the non-trivial\nbundles that can arise from compactly-supported Wannier-type functions are\nthose that may possess, in each of $d$ directions, the non-trivial winding that\ncan occur in the same symmetry class in one dimension, but nothing else. The\nresults are obtained from a very natural usage of algebraic $K$-theory, based\non a ring of polynomials in $e^{\\pm ik_x}$, $e^{\\pm ik_y}$, . . . , which occur\nas entries in the Fourier-transformed Wannier functions.",
        "positive": "Observation of inverse Anderson transitions in Aharonov-Bohm\n  topolectrical circuits: It is well known that Anderson transition is a disorder-induced\nmetal-insulator transition.Contrary to this conventional wisdom, some\ninvestigations have shown that disorders could destroy the phase coherence of\nlocalized modes in flatbands, making the localized states melt into extended\nstates. This phenomenon is called the inverse Anderson transition. While, to\ndate, the experimental observation of inverse Anderson transitions is still\nlacking. In this work, we report the implementation of inverse Anderson\ntransitions based on Aharonov-Bohm topolectrical circuits. Different types of\ndisorders, including symmetric-correlated, antisymmetric-correlated and\nuncorrelated disorders, can be easily implemented in Aharonov-Bohm circuits by\nengineering the spatial distribution of ground settings. Through the direct\nmeasurements of frequency-dependent impedance responses and time-domain voltage\ndynamics, the inverse Anderson transitions induced by antisymmetric-correlated\ndisorders are clearly observed. Moreover, the flat bands and associated spatial\nlocalizations are also fulfilled in clean Aharonov-Bohm circuits or\nAharonov-Bohm circuits sustaining symmetric-correlated and uncorrelated\ndisorders, respectively. Our proposal provides a flexible platform to\ninvestigate the interplay between the geometric localization and Anderson\nlocalization, and could have potential applications in electronic signal\ncontrol."
    },
    {
        "anchor": "Measuring Majorana fermions qubit state and non-Abelian braiding\n  statistics in quenched inhomogeneous spin ladders: We study the Majorana fermions (MFs) in a spin ladder model. We propose and\nnumerically show that the MFs qubit state can be read out by measuring the\nfusion excitation in the quenched inhomogeneous spin ladders. Moreover, we\nconstruct an exactly solvable T-junction spin ladder model, which can be used\nto implement braiding operations of MFs. With the braiding processes simulated\nnumerically as non-equilibrium quench processes, we verify that the MFs in our\nspin ladder model obey the non-Abelian braiding statistics. Our scheme not only\nprovides a promising platform to study the exotic properties of MFs, but also\nhas broad range of applications in topological quantum computation.",
        "positive": "Pseudospin Splitting of the Energy Spectrum of Planar Polytype\n  Graphene-Based Superlattices: The energy spectrum of planar polytype graphene-based superlattices has been\ninvestigated. It is shown that their energy spectrum undergoes pseudospin\nsplitting due to the asymmetry of quantum wells forming the superlattice\npotential profile."
    },
    {
        "anchor": "Materials for Silicon Quantum Dots and their Impact on Electron Spin\n  Qubits: Quantum computers have the potential to efficiently solve problems in\nlogistics, drug and material design, finance, and cybersecurity. However,\nmillions of qubits will be necessary for correcting inevitable errors in\nquantum operations. In this scenario, electron spins in gate-defined silicon\nquantum dots are strong contenders for encoding qubits, leveraging the\nmicroelectronics industry know-how for fabricating densely populated chips with\nnanoscale electrodes. The sophisticated material combinations used in\ncommercially manufactured transistors, however, will have a very different\nimpact on the fragile qubits. We review here some key properties of the\nmaterials that have a direct impact on qubit performance and variability.",
        "positive": "Observation of Dirac cone warping and chirality effects in silicene: We performed low temperature scanning tunneling microscopy (STM) and\nspectroscopy (STS) studies on the electronic properties of (R3xR3)R30{\\deg}\nphase of silicene on Ag(111) surface. We found the existence of Dirac Fermion\nchirality through the observation of -1.5 and -1.0 power law decay of\nquasiparticle interference (QPI) patterns. Moreover, in contrast to the\ntrigonal warping of Dirac cone in graphene, we found that the Dirac cone of\nsilicene is hexagonally warped, which is further confirmed by density\nfunctional calculations and explained by the unique superstructure of silicene.\nOur results demonstrate that the (R3xR3)R30{\\deg} phase is an ideal system to\ninvestigate the unique Dirac Fermion properties of silicene."
    },
    {
        "anchor": "Spatially resolved resonant tunneling on single atoms in silicon: The ability to control single dopants in solid-state devices has opened the\nway towards reliable quantum computation schemes. In this perspective it is\nessential to understand the impact of interfaces and electric fields, inherent\nto address coherent electronic manipulation, on the dopants atomic scale\nproperties. This requires both fine energetic and spatial resolution of the\nenergy spectrum and wave-function, respectively. Here we present an experiment\nfulfilling both conditions: we perform transport on single donors in silicon\nclose to a vacuum interface using a scanning tunneling microscope (STM) in the\nsingle electron tunneling regime. The spatial degrees of freedom of the STM tip\nprovide a versatility allowing a unique understanding of electrostatics. We\nobtain the absolute energy scale from the thermal broadening of the resonant\npeaks, allowing to deduce the charging energies of the donors. Finally we use a\nrate equations model to derive the current in presence of an excited state,\nhighlighting the benefits of the highly tunable vacuum tunnel rates which\nshould be exploited in further experiments. This work provides a general\nframework to investigate dopant-based systems at the atomic scale.",
        "positive": "Low-Temperature Hopping Dynamics with Energy Disorder: Renormalization\n  Group Approach: We formulate a real-space renormalization group (RG) approach for efficient\nnumerical analysis of the low-temperature hopping dynamics in energy-disordered\nlattices. The approach explicitly relies on the time-scale separation of the\ntrapping/escape dynamics. This time-scale separation allows to treat the\nhopping dynamics as a hierarchal process, an RG step being a transformation\nbetween the levels of the hierarchy. We apply the proposed RG approach to\nanalyze hopping dynamics in one- and two-dimensional lattices with varying\ndegree of energy disorder, and find the approach to be more accurate at low\ntemperatures and computationally much faster, than the direct diagonalization.\nApplicability criteria of the proposed approach with respect to the time-scale\nseparation and the maximum number of hierarchy levels are formulated. RG flows\nof energy distribution and preexponents of the Miller-Abrahams model are\nanalyzed."
    },
    {
        "anchor": "Negative Friction Coefficients in Superlubric Graphite-Hexagonal Boron\n  Nitride Heterojunctions: Negative friction coefficients, where friction is reduced upon increasing\nnormal load, are predicted for superlubric graphite-hexagonal boron nitride\nheterojunctions. The origin of this counterintuitive behavior lies in the\nload-induced suppression of the moir\\'e superstructure out-of-plane distortions\nleading to a less dissipative interfacial dynamics. Thermally induced\nenhancement of the out-of-plane fluctuations leads to an unusual increase of\nfriction with temperature. The highlighted frictional mechanism is of a general\nnature and is expected to appear in many layered material heterojunctions.",
        "positive": "Non-Linear Spin Susceptibility in Topological Insulators: We theoretically study the effect of impurity resonances on the indirect\nexchange interaction between magnetic impurities in the surface states of a\nthree-dimensional topological insulator. The interaction is composed of an\nisotropic Heisenberg, and anisotropic Ising and Dzyaloshinskii-Moriya\ncontributions. We find that all three contributions are finite at the Dirac\npoint, which is in stark contrast to the linear response theory which predicts\na vanishing Dzyaloshinskii-Moriya contribution. We show that the\nspin-independent component of the impurity scattering can generate large values\nof the DM term in comparison with the Heisenberg and Ising terms, while these\nlatter contributions drastically reduce in magnitude and undergo sign changes.\nAs a result, both collinear and non-collinear configurations are allowed\nmagnetic configurations of the impurities."
    },
    {
        "anchor": "Theory of interactions between cavity photons induced by a mesoscopic\n  circuit: We use a quantum path integral approach to describe the behavior of a\nmicrowave cavity coupled to a dissipative mesoscopic circuit. We integrate out\nthe mesoscopic electronic degrees of freedom to obtain a cavity effective\naction at fourth order in the light/matter coupling. By studying the structure\nof this action, we establish sufficient conditions in which the cavity dynamics\ncan be described with a Lindblad equation. This equation depends on effective\nparameters set by electronic correlation functions. It reveals that the\nmesoscopic circuit induces an effective Kerr interaction and two-photon\ndissipative processes. We use our method to study the effective dynamics of a\ncavity coupled to a double quantum dot with normal metal reservoirs. If the\ncavity is driven at twice its frequency, the double dot circuit generates\nphotonic squeezing and non-classicalities visible in the cavity Wigner\nfunction. In particular, we find a counterintuitive situation where mesoscopic\ndissipation enables the production of photonic Schr\\\"odinger cats. These\neffects can occur for realistic circuit parameters. Our method can be\ngeneralized straightforwardly to more complex circuit geometries with, for\ninstance, multiple quantum dots, and other types of fermionic reservoirs such\nas superconductors and ferromagnets.",
        "positive": "Density-driven higher-order topological phase transitions in amorphous\n  solids: Amorphous topological states, which are independent of the specific spatial\ndistribution of microscopic constructions, have gained much attention.\nRecently, higher-order topological insulators, which are a new class of\ntopological phases of matter, have been proposed in amorphous systems. Here, we\npropose a density-driven higher-order topological phase transition in a\ntwo-dimensional amorphous system. We demonstrate that the amorphous system\nhosts a topological trivial phase at low density. With an increase in the\ndensity of lattice sites, the topological trivial phase converts to a\nhigher-order topological phase characterized by a quantized quadrupole moment\nand the existence of topological corner states. Furthermore, we confirm that\nthe density-driven higher-order topological phase transition is size dependent.\nIn addition, our results should be general and equally applicable to\nthree-dimensional amorphous systems. Our findings may greatly enrich the study\nof higher-order topological states in amorphous systems."
    },
    {
        "anchor": "Time-crystalline long-range order in squeezed ground state: It is widely believed that ground-state time crystals are not realizable in\nrealistic macroscopic systems. In particular, Watanabe and Oshikawa proved a\ntheorem that implies the absence of the time-dependent long-range order (TDLRO)\nin the ground states of short-range many-body systems. However, this theorem\ndoes not forbid the presence of the ground-state TDLRO for macroscopic\nquantities. In this work, we investigate a simple bosonic model with a squeezed\nground state and point out that the time-dependence of the ground-state TDLRO\nfor the number operator is proportional to the square of the average number in\nthe infinite-squeezing limit, or equivalently, the infinite average-number\nlimit. This result implies the presence of the TDLRO for macroscopic boson\nnumber. We also discuss the physical implementations in optical, spin, and\ntight-binding systems, including the variants. We find an example with the\nmacroscopic TDLRO whose essence is low-lying-state physics and another with\n$marginal$ TDLRO at the quantum critical point. In addition, we reconsider the\ndefinition of the ground-state time crystal in terms of the Floquet picture.",
        "positive": "Perturbative approach to the capacitive interaction between a sensor\n  quantum dot and a charge qubit: We consider the capacitive interaction between a charge qubit and a sensor\nquantum dot(SQD) perturbatively to the second order of their coupling constant\nat zero temperature by utilizing the method of non-equilibrium Green's\nfunctions together with infinite-U Lacroix approximation and employing Majorana\nfermion representation for qubit isospin operators. The effect of back-actions\non dynamics of the system is taken into account by calculating the\nself-energies and the Green's functions in a self-consistent manner. To\ndemonstrate the applicability of the method, we investigate relevant physical\nquantities of the system at zero and finite bias voltages. In the regime of\nweak SQD-qubit coupling, we find a linear relation between the stationary-state\nexpectation values of the third component of the qubit isospin vector,\n$\\left\\langle \\tau_{3}\\right\\rangle $, and the differential conductance of the\nSQD. Furthermore, our numerical results predict that the effect of SQD-qubit\ncoupling on differential conductance of the SQD should be maximized at zero\nbias voltage. Moreover, we obtain an analytical expression to describe the\nbehavior of the differential conductance of the SQD with respect to the qubit\nparameters. Our results at zero bias voltage are consistent with the results of\nnumerical renormalization group method."
    },
    {
        "anchor": "Enhanced emission from a single quantum dot in a microdisk at a\n  deterministic diabolical point: We report on controllable cavity modes through controlling the backscattering\nby two identical scatterers. Periodic changes of the backscattering coupling\nbetween two degenerate cavity modes are observed with the angle between two\nscatterers and elucidated by a theoretical model using two-mode approximation\nand numerical simulations. The periodically appearing single-peak cavity modes\nindicate mode degeneracy at diabolical points. Then interactions between single\nquantum dots and cavity modes are investigated. Enhanced emission of a quantum\ndot with a six-fold intensity increase is obtained in a microdisk at a\ndiabolical point. This method to control cavity modes allows large-scale\nintegration, high reproducibility and fexible design of the size, location,\nquantity and shape for scatterers, which can be applied for integrated photonic\nstructures with scatterer-modified light-matter interaction.",
        "positive": "Ordering of magnetic impurities and tunable electronic properties of\n  topological insulators: We study collective behavior of magnetic adatoms randomly distributed on the\nsurface of a topological insulator. As a consequence of the spin-momentum\nlocking on the surface, the RKKY-type interactions of two adatom spins depend\non the direction of the vector connecting them, thus interactions of an\nensemble of adatoms are frustrated. We show that at low temperatures the\nfrustrated RKKY interactions give rise to two phases: an ordered ferromagnetic\nphase with spins pointing perpendicular to the surface, and a disordered\nspin-glass-like phase. The two phases are separated by a quantum phase\ntransition driven by the magnetic exchange anisotropy. Ferromagnetic ordering\noccurs via a finite-temperature phase transition. The ordered phase breaks\ntime-reversal symmetry spontaneously, driving the surface states into a gapped\nstate, which exhibits an anomalous quantum Hall effect and provides a\nrealization of the parity anomaly. We find that the magnetic ordering is\nsuppressed by potential scattering. Our work indicates that controlled\ndeposition of magnetic impurities provides a way to modify the electronic\nproperties of topological insulators."
    },
    {
        "anchor": "Acoustic M\u00f6bius insulators from projective symmetry: Symmetry plays a critical role in classifying phases of matter. This is\nexemplified by how crystalline symmetries enrich the topological classification\nof materials and enable unconventional phenomena in topologically nontrivial\nones. After an extensive study over the past decade, the list of topological\ncrystalline insulators and semimetals seems to be exhaustive and concluded.\nHowever, in the presence of gauge symmetry, common but not limited to\nartificial crystals, the algebraic structure of crystalline symmetries needs to\nbe projectively represented, giving rise to unprecedented topological physics.\nHere we demonstrate this novel idea by exploiting a projective translation\nsymmetry and constructing a variety of M\\\"obius-twisted topological phases.\nExperimentally, we realize two M\\\"obius insulators in acoustic crystals for the\nfirst time: a two-dimensional one of first-order band topology and a\nthree-dimensional one of higher-order band topology. We observe unambiguously\nthe peculiar M\\\"obius edge and hinge states via real-space visualization of\ntheir localiztions, momentum-space spectroscopy of their 4{\\pi} periodicity,\nand phase-space winding of their projective translation eigenvalues. Not only\ndoes our work open a new avenue for artificial systems under the interplay\nbetween gauge and crystalline symmetries, but it also initializes a new\nframework for topological physics from projective symmetry.",
        "positive": "Geometry effects at conductance quantization in quantum wires: The transmission through quantum wires is studied within a noninteracting\nmodel taking into account the geometry of cleaved edge overgrowth devices. We\nshow that the junction between wide contact and narrow wire has almost no\ninfluence on the transmission through these devices while a potential step\nbetween contact and wire strongly effects the conduction. Our results are\ncompared with recent experimental findings."
    },
    {
        "anchor": "Ultrarelativistic electron-hole pairing in graphene bilayer: We consider ground state of electron-hole graphene bilayer composed of two\nindependently doped graphene layers when a condensate of spatially separated\nelectron-hole pairs is formed. In the weak coupling regime the pairing affects\nonly conduction band of electron-doped layer and valence band of hole-doped\nlayer, thus the ground state is similar to ordinary BCS condensate. At strong\ncoupling, an ultrarelativistic character of electron dynamics reveals and the\nbands which are remote from Fermi surfaces (valence band of electron-doped\nlayer and conduction band of hole-doped layer) are also affected by the\npairing. The analysis of instability of unpaired state shows that s-wave\npairing with band-diagonal condensate structure, described by two gaps, is\npreferable. A relative phase of the gaps is fixed, however at weak coupling\nthis fixation diminishes allowing gapped and soliton-like excitations. The\ncoupled self-consistent gap equations for these two gaps are solved at zero\ntemperature in the constant-gap approximation and in the approximation of\nseparable potential. It is shown that, if characteristic width of the pairing\nregion is of the order of magnitude of chemical potential, then the value of\nthe gap in the spectrum is not much different from the BCS estimation. However,\nif the pairing region is wider, then the gap value can be much larger and\ndepends exponentially on its energy width.",
        "positive": "Polarized photoluminescence clocks ultrafast pseudospin relaxation in\n  graphene: Electronic states in 2D materials can exhibit pseudospin degrees of freedom,\nwhich allow for unique carrier-field interaction scenarios. Here, we\ninvestigate ultrafast sublattice pseudospin relaxation in graphene by means of\npolarization-resolved photoluminescence spectroscopy. Comparison with\nmicroscopic Boltzmann simulations allows to determine a lifetime of the\noptically aligned pseudospin distribution of $12\\pm 2\\,\\text{fs}$. This\nexperimental approach extends the toolbox of graphene pseudospintronics,\nproviding novel means to investigate pseudospin dynamics in active devices or\nunder external fields."
    },
    {
        "anchor": "Reconfigurable 3D magnonic crystal: tunable and localized spin-wave\n  excitations in CoFeB meander-shaped film: In this work, we study experimentally by broadband ferromagnetic resonance\nmeasurements, the dependence of the spin-wave excitation spectra on the\nmagnetic applied field in CoFeB meander-shaped films. Two different\norientations of the external magnetic field were explored, namely parallel or\nperpendicular to the lattice cores. The interpretation of the field dependence\nof the frequency and spatial profiles of major spin-wave modes were obtained by\nmicromagnetic simulations. We show that the vertical segments lead to the\neasy-axis type of magnetic anisotropy and support the in-phase and out-of-phase\nspin-wave precession amplitude in the vertical segments. The latter could\npotentially be used for the design of tunable metasurfaces or in magnetic\nmemories based on meandering 3D magnetic films.",
        "positive": "Strain manipulation of Majorana fermions in graphene armchair\n  nanoribbons: Graphene nanoribbons with armchair edges are studied for externally enhanced,\nbut realistic parameter values: enhanced Rashba spin-orbit coupling due to\nproximity to a transition metal dichalcogenide like WS$_{2}$, and enhanced\nZeeman field due to exchange coupling with a magnetic insulator like EuS under\napplied magnetic field. The presence of s--wave superconductivity, induced\neither by proximity or by decoration with alkali metal atoms like Ca or Li,\nleads to a topological superconducting phase with Majorana end modes. The\ntopological phase is highly sensitive to the application of uniaxial strain,\nwith a transition to the trivial state above a critical strain well below\n$0.1\\%$. This sensitivity allows for real space manipulation of Majorana\nfermions by applying non-uniform strain profiles. Similar manipulation is also\npossible by applying inhomogeneous Zeeman field or chemical potential."
    },
    {
        "anchor": "Phase controlled superconducting proximity effect probed by tunneling\n  spectroscopy: Using a dual-mode STM-AFM microscope operating below 50mK we measured the\nLocal Density of States (LDoS) along small normal wires connected at both ends\nto superconductors with different phases. We observe that a uniform minigap can\ndevelop in the whole normal wire and in the superconductors near the\ninterfaces. The minigap depends periodically on the phase difference. The\nquasiclassical theory of superconductivity applied to a simplified 1D model\ngeometry accounts well for the data.",
        "positive": "Mechanical Wave Propagation within Nanogold Granular Crystals: We computationally investigate the wave propagation characteristics of\nnanoscopic granular crystals composed of one-dimensionally arrayed gold\nnanoparticles using molecular dynamics simulation. We examine two basic\nconfigurations, i.e. homogeneous lattices and diatomic lattices with\nmass-mismatch. We discover that homogeneous lattices of gold nanospheres\nsupport weakly dissipative and highly localized solitary wave at 300 K, while\ndiatomic lattices have a good tuning ability of transmittance and wave speed.\nWe establish a validated nonlinear spring contact model with the consideration\nof complex interactions between gold nanospheres which reveals the physical\nnature of wave behaviors at nanoscale. This work sheds light on the application\nof nanogold as a novel mechanical wave tuner, qualitatively and fundamentally\ndifferent from its counterpart granular materials at meso- and macroscale."
    },
    {
        "anchor": "Electronic transport in quantum cascade structures: The transport in complex multiple quantum well heterostructures is\ntheoretically described. The model is focused on quantum cascade detectors,\nwhich represent an exciting challenge due to the complexity of the structure\ncontaining 7 or 8 quantum wells of different widths. Electronic transport can\nbe fully described without any adjustable parameter. Diffusion from one subband\nto another is calculated with a standard electron-optical phonon hamiltonian,\nand the electronic transport results from a parallel flow of electrons using\nall the possible paths through the different subbands. Finally, the resistance\nof such a complex device is given by a simple expression, with an excellent\nagreement with experimental results. This relation involves the sum of\ntransitions rates between subbands, from one period of the device to the next\none. This relation appears as an Einstein relation adapted to the case of\ncomplex multiple quantum structures.",
        "positive": "A cascade electronic refrigerator using superconducting tunnel junctions: Micro-refrigerators that operate in the sub-kelvin regime are a key device in\nquantum technology. A well-studied candidate, an electronic cooler using Normal\nmetal - Insulator - Superconductor (NIS) tunnel junctions offers substantial\nperformance and power. However, its superconducting electrodes are severely\noverheated due to exponential suppression of their thermal conductance towards\nlow temperatures, and the cooler performs unsatisfactorily - especially in\npowerful devices needed for practical applications. We employ a second NIS\ncooling stage to thermalize the hot superconductor at the backside of the main\nNIS cooler. Not only providing a lower bath temperature, the second stage\ncooler actively evacuates quasiparticles out of the hot superconductor,\nespecially in the low temperature limit. The NIS cooler approaches its ideal\ntheoretical expectations without compromising cooling power. This cascade\ndesign can also be employed to manage excess heat in other cryo-electronic\ndevices."
    },
    {
        "anchor": "Temperature Dependence of Spin Pumping in Ni81Fe19/NbN Bilayer Thin\n  Films: We present a comprehensive study of broadband spin pumping utilizing the\ninverse spin Hall effect phenomena in bilayer samples comprising Ni81Fe19 (15\nnm) and NbN (with NbN thickness varying from 20 nm to 140 nm), conducted over a\ntemperature and frequency range spanning from 300 K to 4 K and 2 GHz to 12 GHz,\nrespectively. Our investigations reveal a systematic shift in ferromagnetic\nresonance fields, amplitude, and line widths as functions of both frequency and\ntemperature. Notably, we observed a temperature-dependent increase in the spin\nHall angle value, surpassing previously reported values. Furthermore, our\nresults demonstrate a pronounced temperature dependence in the inverse spin\nHall effect voltage, exhibiting a significant reduction below the Tc. This\nreduction in inverse spin Hall effect voltage is accompanied by an increase in\nthe linewidth of the ferromagnetic resonance mode.",
        "positive": "Implementing the Quantum von Neumann Architecture with Superconducting\n  Circuits: The von Neumann architecture for a classical computer comprises a central\nprocessing unit and a memory holding instructions and data. We demonstrate a\nquantum central processing unit that exchanges data with a quantum\nrandom-access memory integrated on a chip, with instructions stored on a\nclassical computer. We test our quantum machine by executing codes that involve\nseven quantum elements: Two superconducting qubits coupled through a quantum\nbus, two quantum memories, and two zeroing registers. Two vital algorithms for\nquantum computing are demonstrated, the quantum Fourier transform, with 66%\nprocess fidelity, and the three-qubit Toffoli OR phase gate, with 98% phase\nfidelity. Our results, in combination especially with longer qubit coherence,\nillustrate a potentially viable approach to factoring numbers and implementing\nsimple quantum error correction codes."
    },
    {
        "anchor": "Electron-Dephasing Time in A Two-Dimensional Spin-Polarized System with\n  Rashba Spin-Orbit Interaction: We calculate the dephasing time $\\tau_{\\phi}(B)$ of an electron in a\ntwo-dimensional quantum well with a Rashba spin-orbit interaction,\nspin-polarized by an arbitrarily large magnetic field parallel to the layer.\n$\\tau_\\phi (B)$ is estimated from the logarithmic corrections to the\nconductivity, within a perturbative approach, that assumes weak isotropic\ndisorder scattering. Our result indicates that for any value of the magnetic\nfield, the dephasing rate changes with respect to its unpolarized state value\nby a universal function whose parameter is the ratio of the Zeeman splitting\nenergy $(E_Z)$ to the spin-orbit interaction $(E_{SOI})$, confirming the\nexperimental report published in Phys. Rev. Lett. {\\bf 94}, 186805 (2005) . In\nthe high field limit, when $E_Z>>E_{SOI}$, the dephasing rate saturates and\nreaches asymptotically to a value equal to twice the spin relaxation rate.",
        "positive": "Electrified magnetic catalysis in three-dimensional topological\n  insulators: The gap equations for the surface quasiparticle propagators in a slab of\nthree-dimensional topological insulator in external electric and magnetic\nfields perpendicular to the slab surfaces are analyzed and solved. A different\ntype of magnetic catalysis is revealed with the dynamical generation of both\nHaldane and Dirac gaps. Its characteristic feature manifests itself in the\ncrucial role that the electric field plays in dynamical symmetry breaking and\nthe generation of a Dirac gap in the slab. It is argued that, for a\nsufficiently large external electric field, the ground state of the system is a\nphase with a homogeneous surface charge density."
    },
    {
        "anchor": "Fano resonance in the nonadiabatic pumped shot noise of a time-dependent\n  potential well: We use the Floquet scattering theory to study the correlation properties of\nthe nonadiabatic pumped dc current and heat flow through a time-dependent\npotential well. Oscillator induced quasibound states of electrons can transit\nto the Floquet states leading to resonant tunneling effect. Virtual electron\nscattering processes can produce pumped heat flow, pumped shot noise and pumped\nheat flow noise, with presence of time and spatial reversal symmetry. When one\nof the Floquet levels matches the quasibound level there strikes a \"Fano\"\nresonance.",
        "positive": "On the dephasing time of the chiral metal: In the low-dimensional disordered systems the dephasing time and the\ninelastic scattering (out-scattering) time are in general different. We show\nthat in the case of the two-dimensional chiral metal which is formed at the\nsurface of a layered three dimensional system, which is exhibiting the integer\nquantum Hall effect these two quantities are essentially the same and their\ntemperature-dependence is T^(-3/2). In particular we show that the results\nobtained using the diagramatic technique and the phase uncertainty approach\nintroduced by A. Stern et al. (Phys. Rev. A 41, 3436 (1990)) for the\nout-scattering and the dephasing time respectively, coincide. We furthermore\nconsider these quantities in the case of the three-dimensional chiral metal,\nwhere similar conclusions are reached."
    },
    {
        "anchor": "High Performance Depletion/Enhancement-Mode beta-Ga2O3 on Insulator\n  (GOOI) Field-effect Transistors with Record Drain Currents of 600/450 mA/mm: In this letter, we report on high performance depletion/enhancement\n(D/E)-mode beta-Ga2O3 on insulator (GOOI) field-effect transistors (FETs) with\nrecord high drain currents (ID) of 600/450 mA/mm, which are nearly one order of\nmagnitude higher than any other reported ID values. The threshold voltage (VT)\ncan be modulated by varying the thickness of the beta-Ga2O3 films and the\nE-mode GOOI FET can be simply achieved by shrinking the beta-Ga2O3 film\nthickness. Benefiting from the good interface between beta-Ga2O3 and SiO2 and\nwide bandgap of beta-Ga2O3, a negligible transfer characteristic hysteresis,\nhigh ID on/off ratio of 10^10, and low subthreshold swing of 140 mV/dec for a\n300 nm thick SiO2 are observed. E-mode GOOI FET with source to drain spacing of\n0.9 um demonstrates a breakdown voltage of 185 V and an average electric field\n(E) of 2 MV/cm, showing the great promise of GOOI FET for future power devices.",
        "positive": "Anisotropic and controllable Gilbert-Bloch dissipation in spin valves: Spin valves form a key building block in a wide range of spintronic concepts\nand devices from magnetoresistive read heads to spin-transfer-torque\noscillators. We elucidate the dependence of the magnetic damping in the free\nlayer on the angle its equilibrium magnetization makes with that in the fixed\nlayer. The spin pumping-mediated damping is anisotropic and tensorial, with\nGilbert- and Bloch-like terms. Our investigation reveals a mechanism for tuning\nthe free layer damping in-situ from negligible to a large value via the\norientation of fixed layer magnetization, especially when the magnets are\nelectrically insulating. Furthermore, we expect the Bloch contribution that\nemerges from the longitudinal spin accumulation in the non-magnetic spacer to\nplay an important role in a wide range of other phenomena in spin valves."
    },
    {
        "anchor": "Uniform Spin Qubit Devices in an All-Silicon 300 mm Integrated Process: Larger arrays of electron spin qubits require radical improvements in\nfabrication and device uniformity. Here we demonstrate excellent qubit device\nuniformity and tunability from 300K down to mK temperatures. This is achieved,\nfor the first time, by integrating an overlapping polycrystalline silicon-based\ngate stack in an 'all-Silicon' and lithographically flexible 300mm flow.\nLow-disorder Si/SiO$_2$ is proved by a 10K Hall mobility of $1.5 \\cdot 10^4$\n$cm^2$/Vs. Well-controlled sensors with low charge noise (3.6\n$\\mu$eV/$\\sqrt{\\mathrm{Hz}}$ at 1 Hz) are used for charge sensing down to the\nlast electron. We demonstrate excellent and reproducible interdot coupling\ncontrol over nearly 2 decades (2-100 GHz). We show spin manipulation and\nsingle-shot spin readout, extracting a valley splitting energy of around 150\n$\\mu$eV. These low-disorder, uniform qubit devices and 300mm fab integration\npave the way for fast scale-up to large quantum processors.",
        "positive": "Theory of wavepacket transport under narrow gaps and spatial textures:\n  non-adiabaticity and semiclassicality: We generalise the celebrated semiclassical wavepacket approach from the\nadiabatic to the non-adiabatic regime. A unified description covering both of\nthese regimes is particularly desired for systems with spatially varying band\nstructures where band gaps of various sizes are simultaneously present, e.g. in\nmoir\\'{e} patterns. For a single wavepacket, alternative to the previous\nderivation by Lagrangian variational approach, we show that the same\nsemiclassical equations of motion can be obtained by introducing a\nspatial-texture-induced force operator similar to the Ehrenfest theorem. For\nsemiclassically computing the current, the ensemble of wavepackets based on\nadiabatic dynamics is shown to well correspond to a phase-space fluid for which\nthe fluid's mass and velocity are two distinguishable properties. This\ndistinction is not inherited to the ensemble of wavepackets with the\nnon-adiabatic dynamics. We extend the adiabatic kinetic theory to the\nnon-adiabatic regime by taking into account decoherence, whose joint action\nwith electric field favours certain form of inter-band coherence. The\nsteady-state density matrix as a function of the phase-space variables is then\nphenomenologically obtained for calculating the transport current. The result,\napplicable with a finite electric field, expectedly reproduces the known\nadiabatic limit by taking the electric field to be infinitesimal, and therefore\nattains a unified description from the adiabatic to the non-adiabatic\nsituations."
    },
    {
        "anchor": "Full counting statistics in a disordered free fermion system: The Full Counting Statistics (FCS) is studied for a one-dimensional system of\nnon-interacting fermions with and without disorder. For two unbiased $L$ site\nlattices connected at time $t=0$, the charge variance increases as the natural\nlogarithm of $t$, following the universal expression $<\\delta N^2> \\approx\n\\frac{1}{\\pi^2}\\log{t}$. Since the static charge variance for a length $l$\nregion is given by $<\\delta N^2> \\approx \\frac{1}{\\pi^2}\\log{l}$, this result\nreflects the underlying relativistic or conformal invariance and dynamical\nexponent $z=1$ of the disorder-free lattice. With disorder and strongly\nlocalized fermions, we have compared our results to a model with a dynamical\nexponent $z \\ne 1$, and also a model for entanglement entropy based upon\ndynamical scaling at the Infinite Disorder Fixed Point (IDFP). The latter\nscaling, which predicts $<\\delta N^2> \\propto \\log\\log{t}$, appears to better\ndescribe the charge variance of disordered 1-d fermions. When a bias voltage is\nintroduced, the behavior changes dramatically and the charge and variance\nbecome proportional to $(\\log{t})^{1/\\psi}$ and $\\log{t}$, respectively. The\nexponent $\\psi$ may be related to the critical exponent characterizing\nspatial/energy fluctuations at the IDFP.",
        "positive": "Interfacial spin-orbit torques: Spin-orbit torques offer a promising mechanism for electrically controlling\nmagnetization dynamics in nanoscale heterostructures. While spin-orbit torques\noccur predominately at interfaces, the physical mechanisms underlying these\ntorques can originate in both the bulk layers and at interfaces. Classifying\nspin-orbit torques based on the region that they originate in provides clues as\nto how to optimize the effect. While most bulk spin-orbit torque contributions\nare well studied, many of the interfacial contributions allowed by symmetry\nhave yet to be fully explored theoretically and experimentally. To facilitate\nprogress, we review interfacial spin-orbit torques from a semiclassical\nviewpoint and relate these contributions to recent experimental results. Within\nthe same model, we show the relationship between different interface transport\nparameters. For charges and spins flowing perpendicular to the interface,\ninterfacial spin-orbit coupling both modifies the mixing conductance of\nmagnetoelectronic circuit theory and gives rise to spin memory loss. For\nin-plane electric fields, interfacial spin-orbit coupling gives rise to torques\ndescribed by spin-orbit filtering, spin swapping and precession. In addition,\nthese same interfacial processes generate spin currents that flow into the\nnon-magnetic layer. For in-plane electric fields in trilayer structures, the\nspin currents generated at the interface between one ferromagnetic layer and\nthe non-magnetic spacer layer can propagate through the non-magnetic layer to\nproduce novel torques on the other ferromagnetic layer."
    },
    {
        "anchor": "Minimal circuit for a flux-controlled Majorana qubit in a quantum\n  spin-Hall insulator: We construct a minimal circuit, based on the top-transmon design, to rotate a\nqubit formed out of four Majorana zero-modes at the edge of a two-dimensional\ntopological insulator. Unlike braiding operations, generic rotations have no\ntopological protection, but they do allow for a full characterization of the\ncoherence times of the Majorana qubit. The rotation is controlled by variation\nof the flux through a pair of split Josephson junctions in a Cooper pair box,\nwithout any need to adjust gate voltages. The Rabi oscillations of the Majorana\nqubit can be monitored via oscillations in the resonance frequency of the\nmicrowave cavity that encloses the Cooper pair box.",
        "positive": "Patterning of dielectric nanoparticles using dielectrophoretic forces\n  generated by ferroelectric polydomain films: A theoretical study of a dielectrophoretic force, i.e. the force acting on an\nelectrically neutral particle in the inhomogeneous electric field, which is\nproduced by a ferroelectric domain pattern, is presented. It has been shown by\nseveral researchers that artificially prepared domain patterns with given\ngeometry in ferroelectric single crystals represent an easy and flexible method\nfor patterning dielectric nanoobjects using dielectrophoretic forces. The\nsource of the dielectrophoretic force is a strong and highly inhomogeneous\n(stray) electric field, which exists in the vicinity of the ferroelectric\ndomain walls at the surface of the ferroelectric film. We analyzed\ndielectrophoretic forces in the model of a ferroelectric film of a given\nthickness with a lamellar 180${}^\\circ$ domain pattern. The analytical formula\nfor the spatial distribution of the stray field in the ionic liquid above the\ntop surface of the film is calculated including the effect of free charge\nscreening. The spatial distribution of the dielectrophoretic force produced by\nthe domain pattern is presented. The numerical simulations indicate that the\nintersection of the ferroelectric domain wall and the surface of the\nferroelectric film represents a trap for dielectric nanoparticles in the case\nof so called positive dielectrophoresis. The effects of electrical neutrality\nof dielectric nanoparticles, free charge screening due to the ionic nature of\nthe liquid, domain pattern geometry, and the Brownian motion on the mechanism\nof nanoparticle deposition and the stability of the deposited pattern are\ndiscussed."
    },
    {
        "anchor": "Spin-wave nonreciprocity based on interband magnonic transitions: We theoretically demonstrate linear spin-wave nonreciprocity in a Ni80Fe20\nnanostripe waveguide, based on interband magnonic transitions induced by a\ntime-reversal and spatialinversion symmetry breaking magnetic field. An\nanalytical coupled-mode theory of spin waves, developed to describe the\ntransitions which are accompanied by simultaneous frequency and wavevector\nshifts of the coupled spin waves, is well corroborated by numerical\nsimulations. Our findings could pave the way for the realization of spin-wave\nisolation and the dynamic control of spin-wave propagation in nanoscale\nmagnonic integrated circuits via an applied magnetic field.",
        "positive": "Second order anisotropy contribution in perpendicular magnetic tunnel\n  junctions: Magnetoresistance loops under in-plane applied field were measured on\nperpendicularly magnetized magnetic tunnel junction (pMTJ) pillars with nominal\ndiameters ranging from 50 to 150 nm. By fitting the hard-axis magnetoresistance\nloops to an analytical model, the effective anisotropy fields in both free and\nreference layers were derived and their variations in temperature range between\n340K and 5K were determined. It is found that an accurate fitting is possible\nonly if a second-order anisotropy term of the form $-K_{2}cos^4{\\theta}$, is\nadded to the fitting model. This higher order contribution exists both in the\nfree and reference layers and its sign is opposite to that of the first order\nanisotropy constant, $K_{1}$. At room temperatures the estimated $-K_{2}/K_{1}$\nratios are 0.1 and 0.24 for the free and reference layers, respectively. The\nratio is more than doubled at low temperatures altering the ground state of the\nreference layer from 'easy-axis' to 'easy-cone' regime. Easy-cone state has\nclear signatures in the shape of the hard-axis magnetoresistance loops. The\nsame behavior was observed in all measured devices regardless of their\ndiameter. The existence of this higher order anisotropy was confirmed\nexperimentally on FeCoB/MgO sheet films by ferromagnetic resonance technique.\nIt is of interfacial nature and is believed to be linked to spatial\nfluctuations at the nanoscale of the anisotropy parameter at the FeCoB/MgO\ninterface, in agreement with Dieny-Vedyayev model."
    },
    {
        "anchor": "Decay of Persistent Spin Helix due to the Spin Relaxation at Boundaries: We study electron spin relaxation in one-dimensional structures of finite\nlength in the presence of Bychkov-Rashba spin-orbit coupling and boundary spin\nrelaxation. Using a spin kinetic equation approach, we formulate boundary\nconditions for the case of a partial spin polarization loss at the boundaries.\nThese boundary conditions are used to derive corresponding boundary conditions\nfor spin drift-diffusion equation. The later is solved analytically for the\ncase of relaxation of a homogeneous spin polarization in 1D finite length\nstructures. It is found that the spin relaxation consists of three stages (in\nsome cases, two) -- an initial D'yakonov-Perel' relaxation is followed by spin\nhelix formation and its subsequent decay. Analytical expressions for the decay\ntime are found. We support our analytical results by results of Monte Carlo\nsimulations.",
        "positive": "Giant magnetoresistance and anomalous transport in phosphorene-based\n  multilayers with noncollinear magnetization: We theoretically investigate the unusual features of the magnetotransport in\na monolayer phosphorene ferromagnetic/normal/ferromagnetic (F/N/F) hybrid\nstructure. We find that the charge conductance can feature a minimum at\nparallel (P) configuration and a maximum near the antiparallel (AP)\nconfiguration of magnetization in the F/N/F structure with $n$-doped F and\n$p$-doped N regions and also a finite conductance in the AP configuration with\nthe N region of $n$-type doping. In particular, the proposed structure exhibits\ngiant magnetoresistance, which can be tuned to unity. This perfect switching is\nfound to show strong robustness with respect to increasing the contact length\nand tuning the chemical potential of the N region with a gate voltage. We also\nexplore the oscillatory behavior of the charge conductance or magnetoresistance\nin terms of the size of the N region. We further demonstrate the penetration of\nthe spin-transfer torque into the right F region and show that, unlike graphene\nstructure, the spin-transfer torque is very sensitive to the chemical potential\nof the N region as well as the exchange field of the F region."
    },
    {
        "anchor": "Role of the radiation-reaction electric field in the optical response of\n  two-dimensional crystals: A classical theory of a radiating two-dimensional crystal is proposed and an\nexpression for the radiative-reaction electric field is derived. This field\nplays an essential role in connecting the microscopic electromagnetic fields\nacting on each dipole of the crystal to the macroscopic one, via the boundary\nconditions for the system. The expression of the radiative-reaction electric\nfield coincides with the macroscopic electric field radiating from the crystal\nand, summed to the incident electric field, generates the total macroscopic\nelectric field.",
        "positive": "Cooling a vibrational mode coupled to a molecular single-electron\n  transistor: We consider a molecular single electron transistor coupled to a vibrational\nmode. For some values of the bias and gate voltage transport is possible only\nby absorption of one ore more phonons. The system acts then as a cooler for the\nmechanical mode at the condition that the electron temperature is lower than\nthe phonon temperature. The final effective temperature of the vibrational mode\ndepends strongly on the bias conditions and can be lower or higher of the\nreservoir in contact with the oscillator. We discuss the efficiency of this\nmethod, in particular we find that there is an optimal value for the\nelectron-phonon coupling that maximizes cooling."
    },
    {
        "anchor": "Identify the topological superconducting order in a multi-band quantum\n  wire: How to distinguish the zero-bias peak (ZBP) caused by the Majorana fermions\nfrom that by the other effects remains a challenge in detecting the topological\norder of a quantum wire. In this paper we propose to distinguish the\ntopological superconducting phase from the topologically trivial phase by\nmaking a Josephson junction of the quantum wire attached to a side lead and\nthen measuring the tunneling conductance through it as the phase difference\nacross the junction $\\phi$ varies. Even if the ZBPs exist in both phases, we\ncan identify the topological superconducting phase by a conductance peak at\n$\\phi=\\pi$ and a nearby butterfly pattern.",
        "positive": "Crystallizing Kagome artificial spin ice: Artificial spin ices are engineered arrays of dipolarly coupled nanobar\nmagnets. They enable direct investigations of fascinating collective phenomena\nfrom their diverse microstates. However, experimental access to ground states\nin the geometrically frustrated systems has proven difficult, limiting studies\nand applications of novel properties and functionalities from the low energy\nstates. Here, we introduce a convenient approach to control the competing\ndiploar interactions between the neighboring nanomagnets, allowing us to tailor\nthe vertex degeneracy of the ground states. We achieve this by tuning the\nlength of selected nanobar magnets in the spin ice lattice. We demonstrate the\neffectiveness of our method by realizing multiple low energy microstates in a\nKagome artificial spin ice, particularly the hardly accessible long range\nordered ground state - the spin crystal state. Our strategy can be directly\napplied to other artificial spin systems to achieve exotic phases and explore\nnew emergent collective behaviors."
    },
    {
        "anchor": "Energy magnetization and transport in systems with a non-zero Berry\n  curvature in a magnetic field: We demonstrate that the well-known expression for the charge magnetization of\na sample with a non-zero Berry curvature can be obtained by demanding that the\nEinstein relation holds for the electric transport current. We extend this\nformalism to the transport energy current and show that the energy\nmagnetization must satisfy a particular condition. We provide a physical\ninterpretation of this condition, and relate the energy magnetization to\ncirculating energy currents in Chern insulators due to chiral edge states. We\nfurther recover the expression for the energy magnetization with this\nalternative formalism. We also solve the Boltzmann Transport Equation for the\nnon-equilibrium distribution function in 2D for systems with a non-zero Berry\ncurvature in a magnetic field. This distribution function can be used to obtain\nthe regular Hall response in time-reversal invariant samples with a non-zero\nBerry curvature, for which there is no anomalous Hall response.",
        "positive": "Strong light-matter interactions between gap plasmons and\n  two-dimensional excitons at ambient condition in a deterministic way: Strong exciton-plasmon interaction between the layered two-dimensional (2D)\nsemiconductors and gap plasmons shows a great potential to implement cavity\nquantum-electrodynamics in ambient condition. However, achieving a robust\nplasmon-exciton coupling with nanocavity is still very challenging, because the\nlayer area is usually small with conventional approaches. Here, we report on a\nrobust strong exciton-plasmon coupling between the gap mode of bowtie and the\nexcitons in MoS$_2$ layers with gold-assisted mechanical exfoliation and the\nnondestructive wet transfer techniques for large-area layer. Benefiting from\nthe ultrasmall mode volume and strong in-plane field, the estimated effective\nexciton number contributing to the coupling is largely reduced. With a\ncorrected exciton transition dipole moment, the exciton numbers are extracted\nwith 40 for the case of monolayer and 48 for 8 layers. Our work paves a way to\nrealize the strong coupling with 2D materials with few excitons at room\ntemperature."
    },
    {
        "anchor": "Fluctuations of persistent current: We theoretically analyze equilibrium fluctuations of persistent current (PC)\nin nanorings. We demonstrate that these fluctuations persist down to zero\ntemperature provided the current operator does not commute with the total\nHamiltonian of the system. For a model of a quantum particle on a ring we\nexplicitly evaluate PC noise power which has the form of sharp peaks at\nfrequencies set by the corresponding interlevel distances. In rings with many\nconducting channels a much smoother and broader PC noise spectrum is expected.\nA specific feature of PC noise is that its spectrum can be tuned by an external\nmagnetic flux indicating the presence of quantum coherence in the system.",
        "positive": "Optically-gated resonant emission in single quantum dots: We report on the resonant emission in coherently-driven single semiconductor\nquantum dots. We demonstrate that an ultra-weak non-resonant laser acts as an\noptical gate for the quantum dot resonant response. We show that the gate laser\nsuppresses Coulomb blockade at the origin of a resonant emission quenching, and\nthat the optically-gated quantum dots systematically behave as ideal two-level\nsystems in both regimes of coherent and incoherent resonant emission."
    },
    {
        "anchor": "Localization landscape for Dirac fermions: In the theory of Anderson localization, a landscape function predicts where\nwave functions localize in a disordered medium, without requiring the solution\nof an eigenvalue problem. It is known how to construct the localization\nlandscape for the scalar wave equation in a random potential, or equivalently\nfor the Schr\\\"{o}dinger equation of spinless electrons. Here we generalize the\nconcept to the Dirac equation, which includes the effects of spin-orbit\ncoupling and allows to study quantum localization in graphene or in topological\ninsulators and superconductors. The landscape function $u(r)$ is defined on a\nlattice as a solution of the differential equation $\\overline{{H}}u(r)=1$,\nwhere $\\overline{{H}}$ is the Ostrowsky comparison matrix of the Dirac\nHamiltonian. Random Hamiltonians with the same (positive definite) comparison\nmatrix have localized states at the same positions, defining an equivalence\nclass for Anderson localization. This provides for a mapping between the\nHermitian and non-Hermitian Anderson model.",
        "positive": "Mechanics of nanoscale wrinkling of graphene on a non-developable\n  spherical surface: The configuration of graphene (GE) sheet conforming to the spherical surface\nsubstrate is studied through theoretical model and molecular simulations. Two\nbasic configurations are observed: fully conformation and wrinkling. The final\nconfiguration of the adsorbed GE results from the competition between two\nenergy terms: the adhesion energy between GE and substrate, the strain energy\nstored in the GE due to the deformations. Here, we derive theoretical solutions\nby accounting for two energy terms, and predict the final morphology of GE on\nthe spherical surface (a special kind of nano-developable curved surface)\nsubstrate with using the phase diagram. A critical cone angle of the absorbed\nGE for an arbitrary spherical surface substrate is obtained. Fully conformation\nof GE is observed when the cone angle of absorbed GE is below the critical\nvalue, otherwise wrinkles appear. Molecular simulations are implemented to\nverify the theoretical model with results agree well with theoretical\npredictions. Results from our present work can offer a guide for designing new\nfunctional graphene electronical devices (such as nanoswithes) and fabricating\nhigh quality nanostructured coating (Fig. 13)."
    },
    {
        "anchor": "An Intrinsic Spin Orbit Torque Nano-Oscillator: Spin torque and spin Hall effect nanooscillators generate high intensity spin\nwave auto oscillations on the nanoscale enabling novel microwave applications\nin spintronics, magnonics, and neuromorphic computing. For their operation,\nthese devices require externally generated spin currents either from an\nadditional ferromagnetic layer or a material with a high spin Hall angle. Here\nwe demonstrate highly coherent field and current tunable microwave signals from\nnanoconstrictions in single 15 and 20 nm thick permalloy layers. Using a\ncombination of spin torque ferromagnetic resonance measurements, scanning\nmicroBrillouin light scattering microscopy, and micromagnetic simulations, we\nidentify the autooscillations as emanating from a localized edge mode of the\nnanoconstriction driven by spin orbit torques. Our results pave the way for\ngreatly simplified designs of auto oscillating nanomagnetic systems only\nrequiring a single ferromagnetic layer.",
        "positive": "Levitation of the quantum Hall extended states in the $B\\to$ 0 limit: We investigate the fate of the quantum Hall extended states within a\ncontinuum model with spatially correlated disorder potentials. The model can be\nprojected onto a couple of the lowest Landau bands. Levitation of the $n=0$\ncritical states is observed if at least the two lowest Landau bands are\nconsidered. The dependence on the magnetic length $l_B=(\\hbar/(eB))^{1/2}$ and\non the correlation length of the disorder potential $\\eta$ is combined into a\nsingle dimensionless parameter $\\hat\\eta=\\eta/l_B$. This enables us to study\nthe behavior of the critical states for vanishing magnetic field. In the two\nLandau band limit, we find a disorder dependent saturation of the critical\nstates' levitation which is in contrast to earlier propositions, but in accord\nwith some experiments."
    },
    {
        "anchor": "Local work-function manipulation by external optical stimulation: Strongly differing static dipole moments of the trans and cis isomers of\nphotochromic azobenzene allow for optical switching the work function of\nazobenzene-functionalized self-assembled monolayers (SAMs). We apply these\nproperties in a fundamental experiment to manipulate the area size of the\nswitched SAM. Azobenzene molecules were excited by ultraviolet laser\nillumination and the transient isomerization profile of the SAM was spatially\nresolved recording photoemission electron microscopy (PEEM) images. Thereby we\ndemonstrate the spatial tuning of the SAM work-function and discuss the role of\nthe laser spot-profile in generating sharp edges or gradual changes of the work\nfunction.",
        "positive": "Restoring Coherence Lost to a Slow Interacting Mesoscopic Bath: For a two-state quantum object interacting with a slow mesoscopic interacting\nspin bath, we show that a many-body solution of the bath dynamics conditioned\non the quantum-object state leads to an efficient control scheme to recover the\nlost quantum-object coherence through disentanglement. We demonstrate the\ntheory with the realistic problem of one electron spin in a bath of many\ninteracting nuclear spins in a semiconductor quantum dot. The spin language is\neasily generalized to a quantum object in contact with a bath of interacting\nmulti-level quantum units with the caveat that it is mesoscopic and its\ndynamics is slow compared with the quantum object."
    },
    {
        "anchor": "Three Lectures On Topological Phases Of Matter: These notes are based on lectures at the PSSCMP/PiTP summer school that was\nheld at Princeton University and the Institute for Advanced Study in July,\n2015. They are devoted largely to topological phases of matter that can be\nunderstood in terms of free fermions and band theory. They also contain an\nintroduction to the fractional quantum Hall effect from the point of view of\neffective field theory.",
        "positive": "Nonadiabatic nonlinear non-Hermitian quantized pumping: We analyze a quantized pumping in a nonlinear non-Hermitian photonic system\nwith nonadiabatic driving. The photonic system is made of a waveguide array,\nwhere the distances between adjacent waveguides are modulated. It is described\nby the Su-Schrieffer-Heeger model together with a saturated nonlinear gain term\nand a linear loss term. A topological interface state between the topological\nand trivial phases is stabilized by the combination of a saturated nonlinear\ngain term and a linear loss term. We study the pumping of the topological\ninterface state. We define the transfer-speed ratio $\\omega /\\Omega $ by the\nratio of the pumping speed $% \\omega $ of the center of mass of the wave packet\nto the driving speed $ \\Omega $ of the topological interface. It is quantized\nas $\\omega /\\Omega =1$ in the adiabatic limit. It remains to be quantized for\nslow driving even in the nonadiabatic regime, which is a nonadiabatic quantized\npump. On the other hand, there is almost no pump for fast driving. We find a\ntransition in pumping as a function of the driving speed."
    },
    {
        "anchor": "Interlayer Exciton Laser with Extended Spatial Coherence in an\n  Atomically-Thin Heterostructure: Two-dimensional semiconductors have emerged as a new class of materials for\nnanophotonics for their strong exciton-photon interaction and flexibility for\nengineering and integration. Taking advantage of these properties, we engineer\nan efficient lasing medium based on dipolar interlayer excitons, in\nrotationally aligned atomically thin heterostructures. Lasing is measured from\na transition metal dichalcogenide hetero-bilayer integrated in a silicon\nnitride grating resonator. A sharp increase in the spatial coherence of the\nemission was observed across the lasing threshold. The work establishes\ninterlayer excitons in two-dimensional heterostructures as a silicon-compatible\ncoherent medium. With electrically tunable light-matter interaction strength\nand long-range dipolar interactions, these interlayer excitons promise both\napplications to low-power, ultrafast laser and modulators and rich many-body\nquantum phenomena.",
        "positive": "Rabi type oscillations in damped single 2D-quantum dot: We present a quantized model of harmonically confined dot atom with inherent\ndamping in the presence of a transverse magnetic field. The model leads to a\nnon hermitian Hamiltonian in real coordinate. We have analytically studied the\neffects that damping has on the Rabi type oscillations of the system. The model\nexplains the decoherence of Rabi oscillation in a Josephson Junction."
    },
    {
        "anchor": "Quasiperiodicity, band topology, and moir\u00e9 graphene: A number of moir\\'e graphene systems have nearly flat topological bands where\nelectron motion is strongly correlated. Though microscopically these systems\nare only quasiperiodic, they can typically be treated as translation invariant\nto an excellent approximation. Here we reconsider this question for magic angle\ntwisted bilayer graphene that is nearly aligned with a hexagonal boron\nnitride(h-BN) substrate. We carefully study the effect of the periodic\npotential induced by h-BN on the low energy physics. The combination of this\npotential and the moir\\'e lattice produced by the twisted graphene generates a\nquasi-periodic term that depends on the alignment angle between h-BN and the\nmoir\\'e graphene. We find that the alignment angle has a significant impact on\nboth the band gap near charge neutrality and the behavior of electrical\ntransport. We also introduce and study toy models to illustrate how a\nquasi-periodic potential can give rise to localization and change in transport\nproperties of topological bands.",
        "positive": "Variability mitigation in epitaxial-heterostructure-based spin qubit\n  devices via gate layout optimization: The scalability of spin qubit devices is conditioned by qubit-to-qubit\nvariability. Disorder in the host materials indeed affects the wave functions\nof the confined carriers, which leads to variations in their charge and spin\nproperties. Charge disorder in the amorphous oxides is particularly detrimental\nowing to its long-range influence. Here we analyze the effects of charge traps\nat the semiconductor/oxide interface, which are generally believed to play a\ndominant role in variability. We consider multiple random distributions of\nthese interface traps and numerically calculate their impact on the chemical\npotentials, detuning and tunnel coupling of two adjacent quantum dots in SiGe\nheterostructure. Our results highlight the beneficial screening effect of the\nmetal gates. The surface of the heterostructure shall, therefore, be covered as\nmuch as possible by the gates in order to limit variability. We propose an\nalternative layout with tip-shaped gates that maximizes the coverage of the\nsemiconductor/oxide interface and outperforms the usual planar layout in some\nregimes. This highlights the importance of design in the management of\ndevice-to-device variability."
    },
    {
        "anchor": "Time scales for charge-transfer based operations on Majorana systems: In this article we analyze the efficiency of operations based on transferring\ncharge from a quantum dot (QD) to two coupled topological superconductors,\nwhich can be used for performing nonabelian operations on Majorana bound states\n(MBSs). We develop a method which allows us to describe the full time-evolution\nof the system as the QD energy is manipulated. Using a full counting statistics\nanalysis, we set bounds to the operation time scales. The lower bound depends\non the superconducting phase difference due to a partial decoupling of the\ndifferent MBSs parity sectors, while the upper bound is set by the tunneling of\nquasiparticles to the MBSs. Using realistic parameters, we find the existence\nof a regime where the operation can be carried out with a fidelity close to\nunity. Finally, we propose the use of a two operations protocol to quantify the\neffect of the dephasing and accumulated dynamical phases, demonstrating their\nabsence for certain superconducting phase differences.",
        "positive": "Topological charge localization in bilayer graphene induced by an\n  antisymmetric electric potential step: A charged particle whose energy is less than the electric potential step it\nis incident upon, is expected to undergo partial reflection and transmission.\nIn bilayer graphene, however, a potential step in the form of an antisymmetric\nkink results in particle localization due to the interaction between the\nparticle and its chiral partner. It is found that when the potential step\nexceeds a threshold, zero-energy modes of the system emerge, and causes the\nkink to acquire a charge. The Hall-effect plateaus in the vicinity of the zero\nmodes correspond, unexpectedly, to those of the monolayer. The topological\nnature of these kink-induced effects and the ease with which a kink can be\ngenerated in practice, suggest possible applications in e.g. storage of\ninformation or switching devices."
    },
    {
        "anchor": "Generating many Majorana corner modes and multiple phase transitions in\n  Floquet second-order topological superconductors: A $d$-dimensional, $n$th-order topological insulator or superconductor has\nlocalized eigenmodes at its $(d-n)$-dimensional boundaries ($n\\leq d$). In this\nwork, we apply periodic driving fields to two-dimensional superconductors, and\nobtain a wide variety of Floquet second-order topological superconducting\n(SOTSC) phases with many Majorana corner modes at both zero and $\\pi$\nquasienergies. Two distinct Floquet SOTSC phases are found to be separated by\nthree possible kinds of transformations, i.e., a topological phase transition\ndue to the closing/reopening of a bulk spectral gap, a topological phase\ntransition due to the closing/reopening of an edge spectral gap, or an entirely\ndifferent phase in which the bulk spectrum is gapless. Thanks to the strong\ninterplay between driving and intrinsic energy scales of the system, all the\nfound phases and transitions are highly controllable via tuning a single\nhopping parameter of the system. Our discovery not only enriches the possible\nforms of Floquet SOTSC phases, but also offers an efficient scheme to generate\nmany coexisting Majorana zero and $\\pi$ corner modes that may find applications\nin Floquet quantum computation.",
        "positive": "Aharonov-Bohm differential conductance modulation in defective metallic\n  single-wall carbon nanotubes: Using a perturbative approach, the effects of the energy gap induced by the\nAharonov-Bohm (AB) flux on the transport properties of defective metallic\nsingle-walled carbon nanotubes (MSWCNTs) are investigated. The electronic waves\nscattered back and forth by a pair of impurities give rise to Fabry-Perot\noscillations which constitutes a coherent backscattering interference pattern\n(CBSIP). It is shown that, the CBSIP is aperiodically modulated by applying a\nmagnetic field parallel to the nanotube axis. In fact, the AB-flux brings this\nCBSIP under control by an additional phase shift. As a consequence, the extrema\nas well as zeros of the CBSIP are located at the irrational fractions of the\nquantity $\\Phi_\\rho={\\Phi}/{\\Phi_0}$, where $\\Phi$ is the flux piercing the\nnanotube cross section and $\\Phi_{0}=h/e$ is the magnetic quantum flux. Indeed,\nthe spacing between two adjacent extrema in the magneto-differential\nconductance (MDC) profile is decreased with increasing the magnetic field. The\nfaster and higher and slower and shorter variations is then obtained by\nmetallic zigzag and armchair nanotubes, respectively. Such results propose that\ndefective metallic nanotubes could be used as magneto-conductance switching\ndevices based on the AB effect."
    },
    {
        "anchor": "Stability of Biskyrmions in Centrosymmetric Magnetic Films: Motivated by the observation of biskyrmions in centrosymmetric magnetic films\n(Yu et al. Nature Communications 2014, Wang et al. Advanced Materials 2016), we\ninvestigate analytically and numerically the stability of biskyrmions in films\nof finite thickness, taking into account the nearest-neighbor exchange\ninteraction, perpendicular magnetic anisotropy (PMA), dipole-dipole interaction\n(DDI), and the discreteness of the atomic lattice. The biskyrmion is\ncharacterized by the topological charge $Q=2$, the spatial scale $\\lambda$, and\nanother independent length $d$ that can be interpreted as a separation of two\n$Q=1$ skyrmions inside a $Q=2$ topological defect in the background of uniform\nmagnetization. We find that biskyrmions with $d$ of order $\\lambda$ can be\nstabilized by the magnetic field within a certain range of the ratio of PMA to\nDDI in a film having a sufficient number of atomic layers $N_{z}$. The shape of\nbiskyrmions has been obtained by the numerical minimization of the energy of\ninteracting spins in a $1000\\times1000\\times N_{z}$ atomic lattice. It is close\nto the exact solution of Belavin-Polyakov model when $d$ is below the width of\nthe ferromagnetic domain wall. We compute the magnetic moment of a biskyrmion\nand discuss ways of creating biskyrmions in experiment.",
        "positive": "Nonequilibrium Excitations and Transport of Dirac Electrons in\n  Electric-Field-Driven Graphene: We investigate nonequilibrium excitations and charge transport in\ncharge-neutral graphene driven with DC electric field by using the\nnonequilibrium Green's function technique. Due to the vanishing Fermi surface,\nelectrons are subject to non-trivial nonequilibrium excitations such as highly\nanisotropic momentum distribution of electron-hole pairs, an analog of the\nSchwinger effect. We show that the electron-hole excitations, initiated by the\nLandau-Zener tunneling with a superlinear IV relation $I \\propto E^{3/2}$,\nreaches a steady-state dominated by the dissipation due to optical phonons,\nresulting in a marginally sublinear IV with $I \\propto E$, in agreement with\nrecent experiments. The linear IV starts to show the sign of current saturation\nas the graphene is doped away from the Dirac point, and recovers the\nsemi-classical relation for the saturated velocity. We give a detailed\ndiscussion on the nonequilibrium charge creation and the relation between the\nelectron-phonon scattering rate and the electric field in the steady-state\nlimit. We explain how the apparent Ohmic IV is recovered near the Dirac point.\nWe propose a mechanism where the peculiar nonequilibrium electron-hole creation\ncan be utilized in a novel infra-red device."
    },
    {
        "anchor": "Multipulse Double-Quantum Magnetometry With Near-Surface Nitrogen\n  Vacancy Centers: We discuss multipulse magnetometry that exploits all three magnetic sublevels\nof the S=1 nitrogen-vacancy center in diamond to achieve enhanced magnetic\nfield sensitivity. Based on dual frequency microwave pulsing, the scheme works\nin arbitrary magnetic bias fields and is twice as sensitive to ac magnetic\nfields as conventional two-level magnetometry. We derive the spin evolution\noperator for dual frequency microwave excitation and show its effectiveness for\ndouble-quantum state swaps. Using multipulse sequences of up to 128 pulses\nunder optimized conditions, we show enhancement of the SNR by up to a factor of\n2 in detecting NMR statistical signals, with a 4 times enhancement\ntheoretically possible.",
        "positive": "Signatures of folded branches in the scanning gate microscopy of\n  ballistic electronic cavities: We demonstrate the emergence of classical features in electronic quantum\ntransport for the scanning gate microscopy response in a cavity defined by a\nquantum point contact and a micron-sized circular reflector. The branches in\nelectronic flow characteristic of a quantum point contact opening on a\ntwo-dimensional electron gas with weak disorder are folded by the reflector,\nyielding a complex spatial pattern. Considering the deflection of classical\ntrajectories by the scanning gate tip allows to establish simple relationships\nof the scanning pattern, which are in agreement with recent experimental\nfindings."
    },
    {
        "anchor": "Loop-nodal and Point-nodal Semimetals in Three-dimensional Honeycomb\n  Lattices: Honeycomb structure has a natural extension to the three dimensions. Simple\nexamples are hyperhoneycomb and stripy-honeycomb lattices, which are realized\nin $\\beta $-Li$_{2}$IrO$_{3}$ and $\\gamma $-Li$_{2}$IrO$_{3}$, respectively. We\npropose a wide class of three-dimensional (3D) honeycomb lattices which are\nloop-nodal semimetals. Their edge states have intriguing properties similar to\nthe two-dimensional honeycomb lattice in spite of dimensional difference.\nPartial flat bands emerge at the zigzag or beard edge of the 3D honeycomb\nlattice, whose boundary is given by the Fermi loop in the bulk spectrum.\nAnalytic solutions are explicitly constructed for them. On the other hand,\nperfect flat bands emerge in the zigzag-beard edge or when the anisotropy is\nlarge. All these 3D honeycomb lattices become strong topological insulators\nwith the inclusion of the spin-orbit interaction. Furthermore, point-nodal\nsemimetals may be realized in the presence of both the antiferromagnetic order\nand the spin-orbit interaction.",
        "positive": "Transmission gaps from corrugations: A model including a periodically corrugated thin layer with GaAs substrate is\nemployed to investigate the effects of the corrugations on the transmission\nprobability of the nanostructure. We find that transmission gaps and resonant\ntunneling domains emerge from the corrugations, in the tunneling domains the\ntunneling peaks and valleys result from the boundaries between adjacent regions\nin which electron has different effective masses, and can be slightly modified\nby the layer thickness. These results can provide an access to design a\ncurvature-tunable filter."
    },
    {
        "anchor": "The Difficulty of Gate Control in Molecular Transistors: The electrostatic gating effects on molecular transistors are investigated\nusing the density functional theory (DFT) combined with the nonequilibrium\nGreen's function (NEGF) method. When molecular energy levels are away from the\nFermi energy they can be linearly shifted by the gate voltage, which is\nconsistent with recent experimental observations [Nature 462, 1039 (2009)].\nHowever, when they move near to the Fermi energy (turn-on process), the shifts\nbecome extremely small and almost independent of the gate voltage. The fact\nthat the conductance may be beyond the gate control in the \"ON\" state will\nchallenge the implementation of molecular transistors.",
        "positive": "Magnetic field-induced giant enhancement of electron-phonon energy\n  transfer in strongly disordered conductors: Relaxation of soft modes (e.g. charge density in gated semiconductor\nheterostructures, spin density in the presence of magnetic field) slowed down\nby disorder may lead to giant enhancement of energy transfer (cooling power)\nbetween overheated electrons and phonons at low bath temperature. We show that\nin strongly disordered systems with time-reversal symmetry broken by external\nor intrinsic exchange magnetic field the cooling power can be greatly enhanced.\nThe enhancement factor as large as $10^{2}$ at magnetic field $B \\sim 10$ Tesla\nin 2D {\\rm InSb} films is predicted. A similar enhancement is found for the\nultrasound attenuation."
    },
    {
        "anchor": "Temperature dependent transport characteristics of graphene/n-Si diodes: Realizing an optimal Schottky interface of graphene on Si is challenging, as\nthe electrical transport strongly depends on the graphene quality and the\nfabrication processes. Such interfaces are of increasing research interest for\nintegration in diverse electronic devices as they are thermally and chemically\nstable in all environments, unlike standard metal/semiconductor interfaces. We\nfabricate such interfaces with n-type Si at ambient conditions and find their\nelectrical characteristics to be highly rectifying, with minimal reverse\nleakage current ($<$10$^{-10}$ A) and rectification of more than $10^6$. We\nextract Schottky barrier height of 0.69 eV for the exfoliated graphene and 0.83\neV for the CVD graphene devices at room temperature. The temperature dependent\nelectrical characteristics suggest the influence of inhomogeneities at the\ngraphene/n-Si interface. A quantitative analysis of the inhomogeneity in\nSchottky barrier heights is presented using the potential fluctuation model\nproposed by Werner and G\\\"{u}ttler.",
        "positive": "Electron-avalanche amplifier based on the electronic Venturi effect: Scattering of otherwise ballistic electrons far from equilibrium is\ninvestigated in a cold two-dimensional electron system. The interaction between\nexcited electrons and the degenerate Fermi liquid induces a positive charge in\na nanoscale region which would be negatively charged for diffusive transport at\nlocal thermal equilibrium. In a three-terminal device we observe avalanche\namplification of electrical current, resulting in a situation comparable to the\nVenturi effect in hydrodynamics. Numerical calculations using a random phase\napproximation are in agreement with our data and suggest Coulomb interaction as\nthe dominant scattering mechanism."
    },
    {
        "anchor": "Floquet approach to bichromatically driven cavity optomechanical systems: We develop a Floquet approach to solve time-periodic quantum Langevin\nequations in steady state. We show that two-time correlation functions of\nsystem operators can be expanded in a Fourier series and that a generalized\nWiener-Khinchin theorem relates the Fourier transform of their zeroth Fourier\ncomponent to the measured spectrum. We apply our framework to bichromatically\ndriven cavity optomechanical systems, a setting in which mechanical oscillators\nhave recently been prepared in quantum-squeezed states. Our method provides an\nintuitive way to calculate the power spectral densities for time-periodic\nquantum Langevin equations in arbitrary rotating frames.",
        "positive": "Holographic reconstruction of the interlayer distance of bilayer\n  two-dimensional crystal samples from their convergent beam electron\n  diffraction patterns: The convergent beam electron diffraction (CBED) patterns of twisted bilayer\nsamples exhibit interference patterns in their CBED spots. Such interference\npatterns can be treated as off-axis holograms and the phase of the scattered\nwaves, meaning the interlayer distance can be reconstructed. A detailed\nprotocol of the reconstruction procedure is provided in this study. In\naddition, we derive an exact formula for reconstructing the interlayer distance\nfrom the recovered phase distribution, which takes into account the different\nchemical compositions of the individual monolayers. It is shown that one\ninterference fringe in a CBED spot is sufficient to reconstruct the distance\nbetween the layers, which can be practical for imaging samples with a\nrelatively small twist angle or when probing small sample regions. The quality\nof the reconstructed interlayer distance is studied as a function of the twist\nangle. At smaller twist angles, the reconstructed interlayer distance\ndistribution is more precise and artefact free. At larger twist angles,\nartefacts due to the moir\\'e structure appear in the reconstruction. A method\nfor the reconstruction of the average interlayer distance is presented. As for\nresolution, the interlayer distance can be reconstructed by the holographic\napproach at an accuracy of 0.5 A, which is a few hundred times better than the\nintrinsic z-resolution of diffraction limited resolution, as expressed through\nthe spread of the measured k-values. Moreover, we show that holographic CBED\nimaging can detect variations as small as 0.1 A in the interlayer distance,\nthough the quantitative reconstruction of such variations suffers from large\nerrors."
    },
    {
        "anchor": "Correlated two-electron transport: a principle for a novel charge pump: By considering a correlated two-electron transport process (TET) and using a\ndiagrammatic analysis within the Keldysh nonequilibrium Green's function\nformalism, we discuss a novel charge pump by which carriers are pumped from a\ncontact with low chemical potential to another contact with a higher potential.\nThe TET process involves two correlated incident electrons scattering and\nexchanging energy with each other. The process can significantly affect charge\ncurrent density and it involves high empty states and/or low filled states of\nthe Fermi liquid of the leads.",
        "positive": "Selection and jump rules in electronic Raman scattering from\n  GaAs/Al_{x}Ga_{1-x}As artificial atoms: A theoretical description of electronic Raman scattering from\nGaAs/Al_{x}Ga_{1-x}As artificial atoms under the influence of an external\nmagnetic field is presented. Raman spectra with laser excitation energy in the\ninterval E_{gap}-30 meV to E_{gap} are computed in the polarized and\ndepolarized geometry. The polarization ratios for the collective and\nsingle-particle excitations indicate a breakdown of the Raman polarization\nselection rules once the magnetic field is switched on. A Raman intensity jump\nrule at the band gap is predicted in our calculations. This rule can be a\nuseful tool for identifying the physical nature (charge or spin) of the\nelectronic excitations in quantum dots in low magnetic fields."
    },
    {
        "anchor": "Electron quantum optics with beam splitters and waveguides in Dirac\n  Matter: An electron behaves as both a particle and a wave. On account of this it can\nbe controlled in a similar way to a photon and electronic devices can be\ndesigned in analogy to those based on light when there is minimal excitation of\nthe underlying Fermi sea. Here splitting of the electron wavefunction is\nexplored for systems supporting Dirac type physics, with a focus on graphene\nbut being equally applicable to electronic states in topological insulators,\nliquid helium, and other systems described relativistically. Electron\nbeam-splitters and superfocusers are analysed along with propagation through\nnanoribbons, demonstrating that the waveform, system geometry, and energies all\nneed to balance to maximise the probability density and hence lifetime of the\nflying electron. These findings form the basis for novel quantum electron\noptics.",
        "positive": "Kubo-Greenwood Electrical Conductivity Formulation and Implementation\n  for Projector Augmented Wave Datasets: As the foundation for a new computational implementation, we survey the\ncalculation of the complex electrical conductivity tensor based on the\nKubo-Greenwood (KG) formalism (J.\\ Phys.\\ Soc.\\ Jpn. \\textbf{12}, 570 (1957);\nProc.\\ Phys.\\ Soc.\\ \\textbf{71}, 585 (1958)), with emphasis on derivations and\ntechnical aspects pertinent to use of projector augmented wave datasets with\nplane wave basis sets (Phys.\\ Rev.\\ B \\textbf{50}, 17953 (1994)). New\nanalytical results and a full implementation of the KG approach in an\nopen-source Fortran 90 post-processing code for use with Quantum Espresso (J.\\\nPhys.\\ Cond.\\ Matt.\\ \\textbf{21}, 395502 (2009)) are presented.Named KGEC\n([K]ubo [G]reenwood [E]lectronic [C]onductivity), the code calculates the full\ncomplex conductivity tensor (not just the average trace). It supports use of\neither the original KG formula or the popular one approximated in terms of a\nDirac delta function. It provides both Gaussian and Lorentzian representations\nof the Dirac delta function (thoughthe Lorentzian is preferable on basic\ngrounds). KGEC provides decomposition of the conductivity into intra- and\ninter-band contributions as well as degenerate state contributions. It\ncalculates the dc conductivity tensor directly. It is MPI parallelized over\nk-points, bands, and plane waves, with an option to recover the plane wave\nprocesses for their use in band parallelization as well. It is designed to\nprovide rapid convergence with respect to $\\mathbf k$-point density. Examples\nof its use are given."
    },
    {
        "anchor": "Shot noise in chaotic cavities with an arbitrary number of open channels: Using the random matrix approach, we calculate analytically the average\nshot-noise power in a chaotic cavity at an arbitrary number of propagating\nmodes (channels) in each of the two attached leads. A simple relationship\nbetween this quantity, the average conductance and the conductance variance is\nfound. The dependence of the Fano factor on the channel number is considered in\ndetail.",
        "positive": "Coulomb engineering of the bandgap in 2D semiconductors: The ability to control the size of the electronic bandgap is an integral part\nof solid-state technology. Atomically-thin two-dimensional crystals offer a new\napproach for tuning the energies of the electronic states based on the\ninterplay between the environmental sensitivity and unusual strength of the\nCoulomb interaction in these materials. By engineering the surrounding\ndielectric environment, we are able to tune the electronic bandgap in\nmonolayers of WS2 and WSe2 by hundreds of meV. We exploit this behavior to\npresent an in-plane dielectric heterostructure with a spatially dependent\nbandgap, illustrating the feasibility of our approach for the creation of\nlateral junctions with nanoscale resolution. This successful demonstration of\nbandgap engineering based on the non-invasive modification of the Coulomb\ninteraction should enable the design of a new class of atomically thin devices\nto advance the limits of size and functionality for solid-state technologies."
    },
    {
        "anchor": "Kondo effect in a one-electron double quantum dot: Oscillations of the\n  Kondo current in a weak magnetic field: We present transport measurements of the Kondo effect in a double quantum dot\ncharged with only one or two electrons, respectively. For the one electron case\nwe observe a surprising quasi-periodic oscillation of the Kondo conductance as\na function of a small perpendicular magnetic field |B| \\lesssim 50mT. We\ndiscuss possible explanations of this effect and interpret it by means of a\nfine tuning of the energy mismatch of the single dot levels of the two quantum\ndots. The observed degree of control implies important consequences for\napplications in quantum information processing.",
        "positive": "Giant spin Hall conductivity in platinum at room temperature: We have demonstrated the electrical generation and detection of spin\npolarization by the spin Hall effect (SHE) in platinum. The experiment was\nperformed in a non-local geometry without the use of ferromagnetic materials or\nmagnetic field. We designed a circuit that uses the SHE to convert a charge\ncurrent to a spin current, and the inverse SHE to convert the spin current back\ninto a charge signal. The experiments were carried out for temperatures from 10\nK up to 290 K. We extracted the spin Hall conductivity and spin diffusion\nlength from the data with the aid of a spin diffusion model, and found the\nvalues of 1.1 $\\times 10^6$ $\\Omega^{-1}$m$^{-1}$ and 80~nm, respectively, at\n290 K. The spin Hall conductivity is two orders of magnitudes larger than the\nprevious record of $3.3\\times10^4$ $\\Omega^{-1}$m$^{-1}$. This observation may\nhave many potential applications in spintronics devices."
    },
    {
        "anchor": "Flux-Tunable Hybridization in a Double Quantum Dot Interferometer: A single electron shared between two levels threaded by a magnetic flux is an\nirreducibly simple quantum system in which interference is predicted to occur.\nWe demonstrate tuning of the tunnel coupling between two such electronic levels\nwith flux, implemented in a loop comprising two quantum dots. Using\nradio-frequency reflectometry of the dots' gate electrodes we extract the\ninter-dot coupling, which exhibits oscillations with a periodicity of one flux\nquantum. In different tunneling regimes we benchmark the oscillations'\ncontrast, and find that their amplitude varies with the levels involved, while\ntunneling is generically not suppressed at oscillation minima. These results\nestablish the feasibility and limitations of parity readout of qubits with\ntunnel couplings tuned by flux.",
        "positive": "Imaging and manipulating electrons in a 1D quantum dot with Coulomb\n  blockade microscopy: Motivated by the recent experiments by the Westervelt group using a mobile\ntip to probe the electronic state of quantum dots formed on a segmented\nnanowire, we study the shifts in Coulomb blockade peak positions as a function\nof the spatial variation of the tip potential, which can be termed \"Coulomb\nblockade microscopy\". We show that if the tip can be brought sufficiently close\nto the nanowire, one can distinguish a high density electronic liquid state\nfrom a Wigner crystal state by microscopy with a weak tip potential. In the\nopposite limit of a strongly negative tip potential, the potential depletes the\nelectronic density under it and divides the quantum wire into two partitions.\nThere the tip can push individual electrons from one partition to the other,\nand the Coulomb blockade micrograph can clearly track such transitions. We show\nthat this phenomenon can be used to qualitatively estimate the relative\nimportance of the electron interaction compared to one particle potential and\nkinetic energies. Finally, we propose that a weak tip Coulomb blockade\nmicrograph focusing on the transition between electron number N=0 and N=1\nstates may be used to experimentally map the one-particle potential landscape\nproduced by impurities and inhomogeneities."
    },
    {
        "anchor": "Spin Dynamics and Spin Transport: Spin-orbit (SO) interaction critically influences electron spin dynamics and\nspin transport in bulk semiconductors and semiconductor microstructures. This\ninteraction couples electron spin to dc and ac electric fields. Spin coupling\nto ac electric fields allows efficient spin manipulating by the electric\ncomponent of electromagnetic field through the electric dipole spin resonance\n(EDSR) mechanism. Usually, it is much more efficient than the magnetic\nmanipulation due to a larger coupling constant and the easier access to spins\nat a nanometer scale. The dependence of the EDSR intensity on the magnetic\nfield direction allows measuring the relative strengths of the competing SO\ncoupling mechanisms in quantum wells. Spin coupling to an in-plane electric\nfield is much stronger than to a perpendicular field. Because electron bands in\nmicrostructures are spin split by SO interaction, electron spin is not\nconserved and spin transport in them is controlled by a number of competing\nparameters, hence, it is rather nontrivial. The relation between spin\ntransport, spin currents, and spin populations is critically discussed.\nImportance of transients and sharp gradients for generating spin magnetization\nby electric fields and for ballistic spin transport is clarified.",
        "positive": "Drude weight fluctuations in many-body localized systems: We numerically investigate the distribution of Drude weights $D$ of many-body\nstates in disordered one-dimensional interacting electron systems across the\ntransition to a many-body localized phase. Drude weights are proportional to\nthe spectral curvatures induced by magnetic fluxes in mesoscopic rings. They\noffer a method to relate the transition to the many-body localized phase to\ntransport properties. In the delocalized regime, we find that the Drude weight\ndistribution at a fixed disorder configuration agrees well with the\nrandom-matrix-theory prediction $P(D) \\propto (\\gamma^2+D^2)^{-3/2}$, although\nthe distribution width $\\gamma$ strongly fluctuates between disorder\nrealizations. A crossover is observed towards a distribution with different\nlarge-$D$ asymptotics deep in the many-body localized phase, which however\ndiffers from the commonly expected Cauchy distribution. We show that the\naverage distribution width $\\langle \\gamma\\rangle $, rescaled by $L\\Delta$,\n$\\Delta$ being the average level spacing in the middle of the spectrum and $L$\nthe systems size, is an efficient probe of the many-body localization\ntransition, as it increases/vanishes exponentially in the delocalized/localized\nphase."
    },
    {
        "anchor": "The Magnetic Susceptibility of Non-Interacting Nanoparticles: We have calculated the low-field magnetic susceptibility $\\chi$ of a system\nconsisting of non-interacting mono-dispersed nanoparticles using a classical\nstatistical approach. The model makes use of the assumption that the axes of\nsymmetry of all nanoparticles are aligned and oriented at a certain angle\n$\\psi$ with respect to the external magnetic field. An analytical expression\nfor the temperature dependence of the susceptibility $\\chi(T)$ above the\nblocking temperature is obtained. The derived expression is a generalization of\nthe Curie law for the case of anisotropic magnetic particles. We show that the\nnormalized susceptibility is a universal function of the ratio of the\ntemperature over the anisotropy constant for each angle $\\psi$. In the case\nthat the easy-axis is perpendicular to the magnetic field the susceptibility\nhas a maximum. The temperature of the maximum allows one to determine the\nanisotropy energy.",
        "positive": "Are conductance plateaus independent events in atomic point contact\n  measurements ? A statistical approach: Room temperature conductance-elongation curves of gold atomic wires are\nmeasured using a Scanning Tunnelling Microscope Break Junction technique.\nLandauer's conductance plateaus are individually identified and statistically\nanalysed. Both the probabilities to observe, and the lengths of the two last\nplateaus (at conductance values close to 2e2/h and 4e2/h) are studied. All\nresults converge to show that the occurrence of these two conductance plateaus\non a conductance-elongation curve are statistically independent events."
    },
    {
        "anchor": "High frequency limit of spectroscopy: We consider an arbitrary quantum mechanical system, initially in its\nground-state, exposed to a time-dependent electromagnetic pulse with a carrier\nfrequency $\\omega_0$ and a slowly varying envelope of finite duration. By\nworking out a solution to the time-dependent Schr\\\"odinger equation in the\nhigh-$\\omega_0$ limit, we find that, to the leading order in $\\omega_0^{-1}$, a\nperfect self-cancellation of the system's linear response occurs as the pulse\nswitches off. Surprisingly, the system's observables are, nonetheless,\ndescribable in terms of a combination of its linear density response function\nand nonlinear functions of the electric field. An analysis of jellium slab and\njellium sphere models reveals a very high surface sensitivity of the considered\nsetup, producing a richer excitation spectrum than accessible within the\nconventional linear response regime. On this basis, we propose a new\nspectroscopic technique, which we provisionally name the Nonlinear\nHigh-Frequency Pulsed Spectroscopy (NLHFPS). Combining the advantages of the\nextraordinary surface sensitivity, the absence of constraints by the\ntraditional dipole selection rules, and the clarity of theoretical\ninterpretation utilizing the linear response time-dependent density functional\ntheory, NLHFPS has a potential to evolve into a powerful characterization\nmethod for nanoscience and nanotechnology.",
        "positive": "Symmetry breaking effects on spin and electronic transport in graphene: The decoration of graphene samples with adatoms or nanoparticles leads to the\nenhancement of spin-orbit interactions as well as to the introduction of\nsymmetry-breaking effects that could have drastic effects on spin and\nelectronic transport phenomena. We present an analysis based on symmetry\nconsiderations and examine the impact on the scattering matrix for graphene\nsystems containing defects that enhance spin-orbit interactions, while\nconserving the electronic total angular momentum. We show that the appearance\nand dominance of skew scattering, and the related observation of valley and/or\nspin Hall effect in decorated graphene samples, suggests the set of symmetries\nthat adatom perturbations should satisfy. We further show that detailed\nmeasurements of the transport and elastic times as a function of carrier\nconcentration make it possible to not only extract the strength of the\nspin-orbit interaction, as suggested before, but also obtain the amplitude of\nthe symmetry-breaking terms introduced. To examine how different terms would\naffect measurements, we also present calculations for typical random\ndistributions of impurities with different perturbations, illustrating the\ndetailed energy dependence of different observables"
    },
    {
        "anchor": "Microcavity quantum-dot systems for non-equilibrium Bose-Einstein\n  condensation: We review the practical conditions required to achieve a non-equilibrium BEC\ndriven by quantum dynamics in a system comprising a microcavity field mode and\na distribution of localised two-level systems driven to a step-like population\ninversion profile. A candidate system based on eight 3.8nm layers of\nIn(0.23)Ga(0.77)As in GaAs shows promising characteristics with regard to the\ntotal dipole strength which can be coupled to the field mode.",
        "positive": "Spin Swapping for an Exchange Magnon Spin Current: We propose the spin swapping effect for an exchange magnon spin current in a\nperpendicularly magnetized ferromagnetic medium with in plane anisotropy on the\nsurface. The excitation of a magnon current flowing along an in-plane direction\nwith an out-of-plane spin polarization leads to the generation of a secondary\nexchange spin current propagating along the out-of-plane direction,\ncharacterized by an in-plane spin polarization. The resulting exchange magnon\nspin current can induce an inverse spin Hall voltage of micro-volts. The\nexchange coupling at the interface between regions with different magnetic\nanisotropies plays a crucial role in generating the spin swapping effect. This\nis in contrast to the recently reported spin swapping for an exchange spin\ncurrent in a canted antiferromagnet due to the Dzyaloshiskii-Moriya\ninteraction."
    },
    {
        "anchor": "Quasiparticle band structure engineering in van der Waals\n  heterostructures via dielectric screening: The idea of combining different two-dimensional (2D) crystals in van der\nWaals heterostructures (vdWHs) has led to a new paradigm for band structure\nengineering with atomic precision. Due to the weak interlayer couplings, the\nband structures of the individual 2D crystals are largely preserved upon\nformation of the heterostructure. However, regardless of the details of the\ninterlayer hybridisation, the size of the 2D crystal band gaps are always\nreduced due to the enhanced dielectric screening provided by the surrounding\nlayers. The effect can be on the order of electron volts, but its precise\nmagnitude is non-trivial to predict because of the non-local nature of the\nscreening in quasi-2D materials, and it is not captured by effective\nsingle-particle methods such as density functional theory. Here we present an\nefficient and general method for calculating the band gap renormalization of a\n2D material embedded in an arbitrary vdWH. The method evaluates the change in\nthe GW self-energy of the 2D material from the change in the screened Coulomb\ninteraction. The latter is obtained using the quantum-electrostatic\nheterostructure (QEH) model. We benchmark the G$\\Delta$W method against full\nfirst-principles GW calculations and use it to unravel the importance of\nscreening-induced band structure renormalisation in various vdWHs. A main\nresult is the observation that the size of the band gap reduction of a given 2D\nmaterial when inserted into a heterostructure scales inversely with the\npolarisability of the 2D material. Our work demonstrates that dielectric\nengineering \\emph{via} van der Waals heterostructuring represents a promising\nstrategy for tailoring the band structure of 2D materials.",
        "positive": "Conductance of Distorted Carbon Nanotubes: We have calculated the effects of structural distortions of armchair carbon\nnanotubes on their electrical transport properties. We found that the bending\nof the nanotubes decreases their transmission function in certain energy ranges\nand leads to an increased electrical resistance. Electronic structure\ncalculations show that these energy ranges contain localized states with\nsignificant $\\sigma$-$\\pi$ hybridization resulting from the increased curvature\nproduced by bending. Our calculations of the contact resistance show that the\nlarge contact resistances observed for SWNTs are likely due to the weak\ncoupling of the NT to the metal in side bonded NT-metal configurations."
    },
    {
        "anchor": "Theory of the Quantum Hall Smectic Phase, I: Low Energy Properties of\n  the Quantum Hall Smectic Fixed Point: We develop an effective low energy theory of the Quantum Hall (QH) Smectic or\nstripe phase of a two-dimensional electron gas in a large magnetic field in\nterms of its Goldstone modes and of the charge fluctuations on each stripe.\nThis liquid crystal phase corresponds to a fixed point which is explicitly\ndemonstrated to be stable against quantum fluctuations at long wavelengths.\nThis fixed point theory also allows an unambiguous reconstruction of the\nelectron operator. We find that quantum fluctuations are so severe that the\nelectron Green function decays faster than any power-law, although slower than\nexponentially, and that consequently there is a deep pseudo-gap in the\nquasiparticle spectrum. We discuss, but do not resolve the stability of the\nquantum Hall smectic to crystallization. Finally, the role of Coulomb\ninteractions and the low temperature thermodynamics of the QH smectic state are\nanalyzed.",
        "positive": "Internal Josephson phenomena in a coupled two-component Bose condensate: We discuss the coherent oscillations between two coupled quantum states of a\nBose-Einstein condensate in two-dimensional space at zero temperature. In the\nsystem we consider, weak interparticle repulsive interactions occur between the\nparticles in state one only, while the state two particles remain\nnon-interacting. Analytical as well as numerical solution of the coupled\nGross-Pitaevskii and Schroedinger equations reveals various regimes of\noscillational dynamics for the relative quantum phase and population imbalance\nbetween the two subsystems of the condensate. We show that, depending on the\nenergy detuning between the two states, the system can exhibit modified\nharmonic and anharmonic Rabi oscillations or can transit to the regime\nanalogous to internal a.c. Josephson effect. Morover, at a certain value of\nenergy detuning, the internal oscillations are fully suppressed."
    },
    {
        "anchor": "Manifestations of electron interactions in photogalvanic effect in\n  chiral nanotubes: Carbon nanotubes provide one of the most accessible experimental realizations\nof one dimensional electron systems. In the experimentally relevant regime of\nlow doping the Luttinger liquid formed by electrons may be approximated by a\nWigner crystal. The crystal-like electronic order suggests that nanotubes\nexhibit effects similar to the M\\\"ossbauer effect where the momentum of an\nemitted photon is absorbed by the whole crystal. We show that the circular\nphotovoltaic effect in chiral nanotubes is of the same nature. We obtain the\nfrequency dependence of the photovoltage and characterize its singularities in\na broad frequency range where the electron correlations are essential. Our\npredictions provide a basis for using the photogalvanic effect as a new\nexperimental probe of electron correlations in nanotubes.",
        "positive": "Algebraic structure of Dirac fermion state in \u03b1-(BDET-TTF)_2I_3: We study the algebraic structure of the Dirac fermion state in the organic\nconductor, \\alpha-(BDET-TTF)_2I_3. We find a pair of generators for the\nHamiltonian of \\alpha-(BDET-TTF)_2I_3 that describes the chirality of Dirac\nfermions. The phase parameters associated with those generators have an\nintimate and simple relationship with the positions of the Dirac points in the\nBrillouin zone. By making use of the form of the generators, a reduced form of\nthe Hamiltonian is constructed that shares some characteristic features of the\nDirac fermions with \\alpha-(BDET-TTF)_2I_3. For the reduced Hamiltonian we\npresent the analytic expression for the Dirac point position that sits at\narbitrary point in the Brillouin zone determined by the hopping parameters."
    },
    {
        "anchor": "Subthermal switching with nanomechanical relays: We present a physical model for electronic switching in cantilever based\nnano-electro-mechanical field effect transistors, focusing on the steepness of\nits switching curve. We find that the subthreshold swing of the voltage\ntransfer characteristic is governed by two separate considerations - the\nability of the charges to correlate together through dipolar interactions and\namplify the active torque, versus the active pull-in forces that drive an\nabrupt phase transition and close the air gap between the tip of the cantilever\nand the drain. For small sized relays, dipolar and short-range Van Der Waals\n'sticking' forces dominate, while for longer cantilevers the capacitive energy\nacquires a major role. The individual pull-in and pull-out phases demonstrate a\nremarkably low subthreshold swing driven by the capacitive forces, sharpened\nfurther by dipolar correlation. The sharp switching, however, comes at the\nexpense of strong hysteresis as the metastable and stable states interchange\nalong the forward and reverse phases of the voltage scan.",
        "positive": "Raman scattering study of InAs nanowire under high pressure: The pressure dependent phonon modes of predominant wurtzite InAs nanowires\nhas been investigated in a diamond anvil cell under hydrostatic pressure up to\n58 GPa. The TO and LO at Gamma point and other optical phonon frequencies\nincrease linearly while the LO TO splitting decreases with pressure. The\nrecorded Raman modes have been used to determine the mode Gruneisen parameters\nand also the value of Borns transverse effective charge. The calculated Borns\ntransverse effective charge exhibits a linear reduction with increasing\npressure implying an increase in covalency of nanowires under compression. The\nintensity of the Raman modes shows a strong enhancement as the energy of E1\nband gap approaches the excitation energy, which has been discussed in terms of\nresonant Raman scattering. An indication of structural phase transformation has\nbeen observed above pressure 10.87 GPa. We propose this transformation may be\nfrom wurtzite to rock salt phase although further experimental and theoretical\nconfirmations are needed."
    },
    {
        "anchor": "The effects of electron-electron interactions on the spin transport\n  dynamics of a two-dimensional electron gas: Spin transport properties of a spin-polarized two-dimensional electron gas\nare studied in the presence of electron-electron interactions. Longitudinal and\ntransverse spin diffusion coefficients are calculated with the quantum\ntransport equation which includes many-particle effects in the random phase\napproximation. We find that the $e$-$e$ scattering, which does not contribute\nto charge drift mobility, has a significant contribution to the spin diffusion.\nThus, $e$-$e$ interaction causes non-negligible effects on the operations of\nproposed devices dependent on spin transport in semiconductor heterostructures.",
        "positive": "Perturbation calculations on interlayer transmission rates from\n  symmetric to antisymmetric channels in parallel armchair nanotube junctions: Partially overlapping two parallel armchair nanotubes are investigated\ntheoretically with the $\\pi$ orbital tight bonding model. Considering the\ninterlayer Hamiltonian as perturbation, we obtain approximate analytical\nformulas of the interlayer transmission rates $T_{\\sigma',\\sigma}$ from channel\n$\\sigma$ to $\\sigma'$ for all the four combinations\n$(\\sigma',\\sigma)=(\\pm,\\pm)$ and $(\\pm,\\mp)$, where suffixes $+$ and $-$\nrepresent symmetric and anti-symmetric channels, respectively, with respect to\nthe mirror plane of each tube. Landauer's formula conductance is equal to the\nsum of them in units of $2e^2/h$. According to the perturbation calculation,\nthe interlayer Hamiltonian is transformed into the parameter\n$w_{\\sigma',\\sigma}$ that determines the analytical formula of\n$T_{\\sigma',\\sigma}$. By comparison with the exact numerical results, the\neffective range of the analytical formulas is discussed. In the telescoped\ncoaxial contact, the off-diagonal part $T_{-,+}+T_{+,-}$ is very small compared\nto the diagonal part $T_{+,+}+T_{-,-}$. In the side contact, on the other hand,\nthe off-diagonal part is more significant than the diagonal part in the zero\nenergy peak of the conductance."
    },
    {
        "anchor": "Is Twisted Bilayer Graphene Stable under Shear?: In twisted bilayer graphene (TBLG), extremely small deviations from the magic\ntwist angle $\\theta_m{\\approx}1.08^\\circ$ change its electronic structure near\nthe Fermi level drastically, causing a meV-wide flat band to appear or\ndisappear. In view of such sensitivity to minute structural deformations, we\ninvestigate the combined effect of shear and atomic relaxation on the\nelectronic structure. Using precise experimental data for monolayer and bilayer\ngraphene as input in a simplified formalism for the electronic structure and\nelastic energy, we find TBLG near $\\theta_m$ to be unstable with respect to\nglobal shear by the angle $\\alpha{\\approx}0.08^\\circ$. In TBLG, the effect of\nshear on the electronic structure is as important as that of atomic relaxation.\nUnder optimum global shear, calculated $\\theta_m$ is reduced by $0.04^\\circ$\nand agrees with the observed value.",
        "positive": "Disorder-free localization around the conduction band edge of crossing\n  and kinked silicon nanowires: We explore ballistic regime quantum transport characteristics of\noxide-embedded crossing and kinked silicon nanowires (NWs) within a large-scale\nempirical pseudopotential electronic structure framework, coupled to the\nKubo-Greenwood transport analysis. A real-space wave function study is\nundertaken and the outcomes are interpreted together with the findings of\nballistic transport calculations. This reveals that ballistic transport edge\nlies tens to hundreds of millielectron volts above the lowest unoccupied\nmolecular orbital, with a substantial number of localized states appearing in\nbetween, as well as above the former. We show that these localized states are\nnot due to the oxide interface, but rather core silicon-derived. They manifest\nthe wave nature of electrons brought to foreground by the reflections\noriginating from NW junctions and bends. Hence, we show that the crossings and\nkinks of even ultraclean Si NWs possess a conduction band tail without a\nrecourse to atomistic disorder."
    },
    {
        "anchor": "Band Gap Engineering with Ultralarge Biaxial Strains in Suspended\n  Monolayer MoS2: We demonstrate the continuous and reversible tuning of the optical band gap\nof suspended monolayer MoS2 membranes by as much as 500 meV by applying very\nlarge biaxial strains. By using chemical vapor deposition (CVD) to grow\ncrystals that are highly impermeable to gas, we are able to apply a pressure\ndifference across suspended membranes to induce biaxial strains. We observe the\neffect of strain on the energy and intensity of the peaks in the\nphotoluminescence (PL) spectrum, and find a linear tuning rate of the optical\nband gap of 99 meV/%. This method is then used to study the PL spectra of\nbilayer and trilayer devices under strain, and to find the shift rates and\nGr\\\"uneisen parameters of two Raman modes in monolayer MoS2. Finally, we use\nthis result to show that we can apply biaxial strains as large as 5.6% across\nmicron sized areas, and report evidence for the strain tuning of higher level\noptical transitions.",
        "positive": "Conducting Electrons in Amorphous Si Nanostructures: Coherent\n  Interference and Metal-Insulator Transitions Mediated by Local Structures: Without a periodic reference framework, local structures in noncrystalline\nsolids are difficult to specify, but they still exert an enormous influence on\nmaterials properties. For example, thermomechanical responses of organic and\ninorganic glasses sensitively depend on the distribution of free volume or soft\nspots$^{1,2}$. Meanwhile, strong electron localization$^{3}$ that endows\nunparalleled electrical breakdown strengths to amorphous insulators is easily\ncompromised by local defects that promote inelastic tunneling over a variable\nrange$^{4,5}$. Here we report how metallic conduction can overcome strong\nlocalization in amorphous insulators of small dimensions, and how local\nstructures can manifest their spectacular influence on such conduction. In\namorphous Si, nanoscale electrons are so coherent that they exhibit robust\nquantum interferences reminiscent of the mesoscopic phenomena seen in weakly\nlocalized metal crystals$^{6}$. Yet ultrasoft Si bonds emerge as the key local\nstructures whose extraordinarily strong electron-phonon interaction coerces\nitinerant electrons into moving slowly at low temperature, even becoming\ntrapped at all temperature when Si-O/N sites are provided. The local structures\ncan be manipulated by a voltage or pressure to regulate charge storage, charge\nflow and metal-insulator transition. Also made of Ge and oxides and nitrides,\nnanostructured amorphous conductors could offer opportunities for new\napplications."
    },
    {
        "anchor": "Reversible tuning of omnidirectional band gaps in two-dimensional\n  magnonic crystals by magnetic field and in-plane squeezing: By means of the plane wave method, we study nonuniform, i.e., mode- and\nk-dependent, effects in the spin-wave spectrum of a two-dimensional bicomponent\nmagnonic crystal. We use the crystal based on a hexagonal lattice squeezed in\nthe direction of the external magnetic field wherein the squeezing applies to\nthe lattice and the shape of inclusions. The squeezing changes both the\ndemagnetizing field and the spatial confinement of the excitation, which may\nlead to the occurrence of an omnidirectional magnonic band gaps. In particular,\nwe study the role played by propagational effects, which allows us to explain\nthe k-dependent softening of modes. The effects we found enabled us not only to\ndesign the width and position of magnonic band gaps, but also to plan their\nresponse to a change in the external magnetic field magnitude. This allows the\nreversible tuning of magnonic band gaps, and it shows that the studied\nstructures are promising candidates for designing magnonic devices that are\ntunable during operation.",
        "positive": "A new route to negative refractive index from topological metals: We theoretically discuss the possibility of realizing the negative refractive\nindex in Weyl/Dirac semimetals. We consider the Maxwell equations with the\nplasma gap and the chiral magnetic effect. We study the dispersion relations of\nelectromagnetic waves, and show that the refractive index becomes negative at\nfrequencies (just) below the plasma frequency. We find that axial anomaly, or\nmore specifically, negative magnetoresistance (electric current parallel to\nmagnetic fields) opens a new route to realize the negative refractive index.\nReflection and transmission coefficients are computed in a slab of Weyl/Dirac\nsemimetals."
    },
    {
        "anchor": "Nontrivial surface topological physics from strong and weak topological\n  insulators and superconductors: We investigate states on the surface of strong and weak topological\ninsulators and superconductors that have been gapped by a symmetry breaking\nterm. The surface of a strong 3D topological insulator gapped by a magnetic\nmaterial is well known to possess a half quantum Hall effect. Furthermore, it\nhas been known that the surface of a weak 3D topological insulator gapped by a\ncharge density wave exhibits a half quantum spin Hall effect. To generalize\nthese results to all Altland-Zirnbauer symmetry classes of topological\ninsulators and superconductors, we reproduce the classification table for the\nten symmetry classes by using the representation theory of Clifford algebras\nand construct minimal-size Dirac Hamiltonians. We find that if the surface\ndimension and symmetry class possesses a $\\mathbb{Z}$ or $\\mathbb{Z}_2$\ntopological invariant, then the resulting surface state with a gapped symmetry\nbreaking term may have a nontrivial topological phase.",
        "positive": "The optical response of artificially twisted MoS$_2$ bilayers: Two-dimensional layered materials offer the possibility to create artificial\nvertically stacked structures possessing an additional degree of freedom -\n$the$ $interlayer$ $twist$. We present a comprehensive optical study of\nartificially stacked bilayers (BLs) MoS$_2$ encapsulated in hexagonal BN with\ninterlayer twist angle ranging from 0 to 60 degrees using Raman scattering and\nphotoluminescence spectroscopies. It is found that the strength of the\ninterlayer coupling in the studied BLs can be estimated using the energy\ndependence of indirect emission versus the A$_\\textrm{1g}$-E$_\\textrm{2g}^1$\nenergy separation. Due to the hybridization of electronic states in the valence\nband, the emission line related to the interlayer exciton is apparent in both\nthe natural (2H) and artificial (62$^\\circ$) MoS$_2$ BLs, while it is absent in\nthe structures with other twist angles. The interlayer coupling energy is\nestimated to be of about 50 meV. The effect of temperature on energies and\nintensities of the direct and indirect emission lines in MoS$_2$ bilayers is\nalso quantified."
    },
    {
        "anchor": "Chirality inversion of Majorana edge modes in a Fu-Kane heterostructure: Fu and Kane have discovered that a topological insulator with induced s-wave\nsuperconductivity (gap $\\Delta_0$, Fermi velocity $v_{\\rm F}$, Fermi energy\n$\\mu$) supports chiral Majorana modes propagating on the surface along the edge\nwith a magnetic insulator. We show that the direction of motion of the Majorana\nfermions can be inverted by the counterflow of supercurrent, when the Cooper\npair momentum along the boundary exceeds $\\Delta_0^2/\\mu v_{\\rm F}$. The\nchirality inversion is signaled by a doubling of the thermal conductance of a\nchannel parallel to the supercurrent. Moreover, the inverted edge can transport\na nonzero electrical current, carried by a Dirac mode that appears when the\nMajorana mode switches chirality. The chirality inversion is a unique signature\nof Majorana fermions in a spinful topological superconductor: it does not exist\nfor spinless chiral p-wave pairing.",
        "positive": "Valley splitting of single-electron Si MOS quantum dots: Silicon-based metal-oxide-semiconductor quantum dots are prominent candidates\nfor high-fidelity, manufacturable qubits. Due to silicon's band structure,\nadditional low-energy states persist in these devices, presenting both\nchallenges and opportunities. Although the physics governing these valley\nstates has been the subject of intense study, quantitative agreement between\nexperiment and theory remains elusive. Here, we present data from a new\nexperiment probing the valley states of quantum dot devices and develop a\ntheory that is in quantitative agreement with both the new experiment and a\nrecently reported one. Through sampling millions of realistic cases of\ninterface roughness, our method provides evidence that, despite radically\ndifferent processing, the valley physics between the two samples is essentially\nthe same. This work provides the first evidence that valley splitting can be\ndeterministically predicted and controlled in metal oxide semiconductor quantum\ndots, a critical requirement for such systems to realize a reliable qubit\nplatform."
    },
    {
        "anchor": "Interaction effects on thermal transport in quantum wires: We develop a theory of thermal transport of weakly interacting electrons in\nquantum wires. Unlike higher-dimensional systems, a one-dimensional electron\ngas requires three-particle collisions for energy relaxation. The fastest\nrelaxation is provided by the intrabranch scattering of comoving electrons\nwhich establishes a partially equilibrated form of the distribution function.\nThe thermal conductance is governed by the slower interbranch processes which\nenable energy exchange between counterpropagating particles. We derive an\nanalytic expression for the thermal conductance of interacting electrons valid\nfor arbitrary relation between the wire length and electron thermalization\nlength. We find that in sufficiently long wires the interaction-induced\ncorrection to the thermal conductance saturates to an interaction-independent\nvalue.",
        "positive": "Electronic and structural characterization of divacancies in irradiated\n  graphene: We provide a thorough study of a carbon divacancy, a fundamental but almost\nunexplored point defect in graphene. Low temperature scanning tunneling\nmicroscopy (STM) imaging of irradiated graphene on different substrates enabled\nus to identify a common two-fold symmetry point defect. Our first principles\ncalculations reveal that the structure of this type of defect accommodates two\nadjacent missing atoms in a rearranged atomic network formed by two pentagons\nand one octagon, with no dangling bonds. Scanning tunneling spectroscopy (STS)\nmeasurements on divacancies generated in nearly ideal graphene show an\nelectronic spectrum dominated by an empty-states resonance, which is ascribed\nto a spin-degenerated nearly flat band of $\\pi$-electron nature. While the\ncalculated electronic structure rules out the formation of a magnetic moment\naround the divacancy, the generation of an electronic resonance near the Fermi\nlevel, reveals divacancies as key point defects for tuning electron transport\nproperties in graphene systems."
    },
    {
        "anchor": "Nuclear resonant scattering of synchrotron radiation by physisorbed Kr\n  on TiO$_{2}$(110) surfaces in multilayer and monolayer regimes: Physisorbed Kr layers on TiO$_{2}$(110) surfaces were investigated by means\nof nuclear resonant scattering (NRS) of synchrotron radiation at Kr thicknesses\nranging from multilayer to monolayer. The NRS intensity was measured as a\nfunction of the Kr exposure, from which the NRS signal corresponding to\nmonolayer was estimated as 0.23 cps. The time spectra measured at various\nthicknesses showed a monotonous decay without any quantum beat features. The\nrecoiless fraction $f$ evaluated from the analysis of the time spectrum\nrevealed a substantial reduction upon temperature rise from 19 to 25 K. As its\norigin, an order-disorder phase transition of the monolayer Kr is proposed.",
        "positive": "A Virtual Young's Double Slit Experiment for Hard X-ray Photons: We have implemented a virtual Young's double slit experiment for hard X-ray\nphotons with micro-fabricated bi-prisms. We observe fringe patterns with a\nscintillator, and quantify interferograms by detecting X-ray fluorescence from\na scanned 30nm Cr metal film. The observed intensities are best modeled with a\nnear-field, Fresnel analysis. The maximum fringe number in the overlap region\nis proportional to the ratio of real to imaginary parts refractive index of the\nprism material. The horizontal and vertical transverse coherence lengths at\nbeamline APS 8-ID are measured."
    },
    {
        "anchor": "Probing Near-Field Thermal Emission of Localized Surface Phonons from\n  Silicon Carbide Nanopillars: Thermal emission of localized surface phonons (LSPhs) from nanostructures of\npolaritonic materials is a promising mechanism for tuning the spectrum of\nnear-field thermal radiation. Previous studies have theoretically shown that\nthermal emission of LSPhs results in narrow-band peaks in the near-field\nspectra, whose spectral locations can be modulated by changing the dimensions\nof the nanostructure. However, near-field thermal emission of LSPhs has not\nbeen experimentally explored yet. In this study, we measure the spectrum of\nnear-field thermal radiation from arrays of 6H-silicon carbide (6H-SiC)\nnanopillars using an internal-reflection-element based spectroscopy technique.\nWe present an experimental demonstration of thermal emission of the transverse\ndipole, quadrupole, and octupole, as well as longitudinal monopole from 6H-SiC\nnanopillars at a near-field distance from the array. We show that the spectral\nlocation of the longitudinal monopole and transverse dipole are significantly\naffected by the near-field coupling between neighboring nanopillars as well as\nthe intercoupling of the nanopillars and the substrate. We also experimentally\ndemonstrate that the spectrum of near-field thermal radiation from 6H-SiC\nnanopillar arrays can be tuned by varying the dimensions of the nanopillars,\nproviding an opportunity for designing emitters with tailored near-field\nthermal radiation.",
        "positive": "Magnetization spin dynamics in a (LuBi)3Fe5O12 (BLIG) epitaxial film: Bismuth substituted lutetium iron garnet (BLIG) films exhibit larger Faraday\nrotation, and have a higher Curie temperature than yttrium iron garnet. We have\nobserved magnetic stripe domains and measured domain widths of 1.4 {\\mu}{\\mu}m\nusing Fourier domain polarization microscopy, Faraday rotation experiments\nyield a coercive field of 5 Oe. These characterizations form the basis of\nmicromagnetic simulations that allow us to estimate and compare spin wave\nexcitations in BLIG films. We observed that these films support thermal magnons\nwith a precessional frequency of 7 GHz with a line width of 400 MHz. Further,\nwe studied the dependence of precessional frequency on the externally applied\nmagnetic field. Brillouin light scattering experiments and precession\nfrequencies predicted by simulations show similar trend with increasing field."
    },
    {
        "anchor": "Optical coupling between atomically-thin black phosphorus and a two\n  dimensional photonic crystal nanocavity: Atomically-thin black phosphorus (BP) is an emerging two dimensional (2D)\nmaterial exhibiting bright photoluminescence in the near infrared. Coupling its\nradiation to photonic nanostructures will be an important step toward the\nrealization of 2D material based nanophotonic devices that operate efficiently\nin the near infrared, which includes the technologically important optical\ntelecommunication wavelength bands. In this letter, we demonstrate the optical\ncoupling between atomically-thin BP and a 2D photonic crystal nanocavity. We\nemployed a home-build dry transfer apparatus for placing a thin BP flake on the\nsurface of the nanocavity. Their optical coupling was analyzed through\nmeasuring cavity mode emission under optical carrier injection at room\ntemperature.",
        "positive": "Near-field thermal transport between twisted bilayer graphene: Active control of heat flow is of both fundamental and applied interest in\nthermal management and energy conversion. Here, we present a fluctuational\nelectrodynamic study of thermal radiation between twisted bilayer graphene\n(TBLG), motivated by its unusual and highly tunable plasmonic properties. We\nshow that near-field heat flow can vary by more than 10-fold over only a few\ndegrees of twist, and identify special angles leading to heat flow extrema.\nThese special angles are dictated by the Drude weight in the intraband optical\nconductivity of TBLG, and are roughly linear with the chemical potential.\nFurther, we observe multiband thermal transport due to the increasing role of\ninterband transitions as the twist angle decreases, in analogy to monolayer\ngraphene in a magnetic field. Our findings are understood via the surface\nplasmons in TBLG, and highlight its potential for manipulating radiative heat\nflow."
    },
    {
        "anchor": "Environmental Doping-Induced Degradation of the Quantum Anomalous Hall\n  Insulators: The quantum anomalous Hall (QAH) insulator is a topological quantum state\nwith quantized Hall resistance and zero longitudinal resistance in the absence\nof an external magnetic field. The QAH insulator carries spin-polarized\ndissipation-free chiral edge current and thus provides a unique opportunity to\ndevelop energy-efficient transformative information technology. Despite\npromising advances on the QAH effect over the past decade, the QAH insulator\nhas thus far eluded any practical applications. In addition to its low working\ntemperature, the QAH state in magnetically doped topological insulator (TI)\nfilms/heterostructures usually deteriorates with time in ambient conditions. In\nthis work, we prepare three QAH devices with similar initial properties and\nstore them in different environments to investigate the evolution of their\ntransport properties. The QAH device without a protection layer in air show\nclear degradation and becomes hole-doped with the charge neutral point shifting\nsignificantly to positive gate voltages. The QAH device kept in an argon glove\nbox without a protection layer shows no measurable degradation after 560 hours\nand the device protected by a 3 nm AlOx protection layer in air shows minimal\ndegradation with stable QAH properties. Our work shows a route to preserve the\ndissipation-free chiral edge state in QAH devices for potential applications in\nquantum information technology.",
        "positive": "Surface van der Waals Forces in a Nutshell: Most often in chemical physics, long range van der Waals surface interactions\nare approximated by the exact asymptotic result at vanishing distance, the well\nknown additive approximation of London dispersion forces due to Hamaker.\nHowever, the description of retardation effects that is known since the time of\nCasimir is completely neglected for lack of a tractable expression. Here we\nshow that it is possible to describe surface van der Waals forces at arbitrary\ndistances in one single simple equation. The result captures the long sought\ncrossover from non-retarded (London) to retarded (Casimir) interactions, the\neffect of polarization in condensed media and the full suppression of retarded\ninteractions at large distance. This is achieved with similar accuracy and the\nsame material properties that are used to approximate the Hamaker constant in\nconventional applications. The results show that at ambient temperature,\nretardation effects significantly change the power law exponent of the\nconventional Hamaker result for distances of just a few nanometers."
    },
    {
        "anchor": "Robust quantum gates for singlet-triplet spin qubits using composite\n  pulses: We present a comprehensive theoretical treatment of SUPCODE, a method for\ngenerating dynamically corrected quantum gate operations, which are immune to\nrandom noise in the environment, by using carefully designed sequences of soft\npulses. SUPCODE enables dynamical error suppression even when the control field\nis constrained to be positive and uniaxial, making it particularly suited to\ncounteracting the effects of noise in systems subject to these constraints such\nas singlet-triplet qubits. We describe and explain in detail how to generate\nSUPCODE pulse sequences for arbitrary single-qubit gates and provide several\nexplicit examples of sequences that implement commonly used gates, including\nthe single-qubit Clifford gates. We develop sequences for noise-resistant\ntwo-qubit gates for two exchanged-coupled singlet-triplet qubits by cascading\nrobust single-qubit gates, leading to a 35% reduction in gate time compared to\nprevious works. This cascade approach can be scaled up to produce gates for an\narbitrary-length spin qubit array, and is thus relevant to scalable quantum\ncomputing architectures. To more accurately describe real spin qubit\nexperiments, we show how to design sequences that incorporate additional\nfeatures and practical constraints such as sample-specific charge noise models\nand finite pulse rise times. We provide a detailed analysis based on randomized\nbenchmarking to show how SUPCODE gates perform under realistic $1/f^\\alpha$\nnoise and find a strong dependence of gate fidelity on the exponent $\\alpha$,\nwith best performance for $\\alpha>1$. Our SUPCODE sequences can therefore be\nused to implement robust universal quantum computation while accommodating the\nfundamental constraints and experimental realities of singlet-triplet qubits.",
        "positive": "Casimir effects in systems containing 2D layers, like graphene and 2D\n  electron gases: We present a variety of methods to derive the Casimir interaction in planar\nsystems containing two-dimensional layers. Examples where this can be of use is\ngraphene, graphene-like layers and two-dimensional electron gases. We present\nresults for two free standing layers and for one layer above a substrate. The\nresults can easily be extended to systems with a larger number of layers."
    },
    {
        "anchor": "Young's modulus of 2D materials extracted from their nonlinear dynamic\n  response: Due to their atomic-scale thickness, the resonances of 2D material membranes\nshow signatures of nonlinearities at amplitudes of only a few nanometers. While\nthe linear dynamics of membranes is well understood, the exact relation between\nthe nonlinear response and the resonator's material properties has remained\nelusive. In this work, we propose a method to determine the Young's modulus of\nsuspended 2D material membranes from their nonlinear dynamic response. The\nmethod is demonstrated by interferometric measurements on graphene and MoS2\nresonators, which are electrostatically driven into the nonlinear regime at\nmultiple driving forces. It is shown that a set of response curves can be\nfitted by the solutions of the Duffing equation using only one fit parameter,\nfrom which the Young's modulus is extracted using membrane theory. Our method\nis fast, contactless, and provides a platform for high-frequency\ncharacterization of the mechanical properties of 2D materials.",
        "positive": "Relaxation dynamics of spin 3/2 silicon vacancies in 4H-Silicon carbide: Room temperature optically detected magnetic resonance experiments on spin\n3/2 Silicon vacancies in 4H-SiC are reported. The $m_s=+1/2\\leftrightarrow\n-1/2$ transition is accessed using a two microwave frequency excitation\nprotocol. The ratio of the Rabi frequencies of the $+3/2 \\leftrightarrow +1/2$\nand $+1/2\\leftrightarrow -1/2$ transitions is measured to be $(0.901\\pm\n0.013)$. The deviation from $\\sqrt{3}/2$ is attributed to small difference in\ng-factor for different magnetic dipole transitions. Whereas a spin-1/2 system\nis characterized by a single spin lifetime $T_1$, we experimentally demonstrate\nthat the spin 3/2 system has three distinct relaxation modes that can be\npreferentially excited and detected. The measured relaxation times are\n$(0.41\\pm 0.02) T_{slow}=T_d= (3.3\\pm 0.5)T_{fast} $. This differs from the\nvalues of $ T_p/3 =T_d= 2T_f $ expected for pure dipole ($T_p$), quadrupole\n($T_d$), and octupole ($T_f$) relaxation modes, respectively, and implies\nadmixing of the slow dipole and fast octupole relaxation modes."
    },
    {
        "anchor": "Site-selective conductance of sidewall functionalized carbon nanotubes: We use DFT to study the effect of molecular adsorbates on the conductance of\nmetallic carbon nanotubes. The five molecules considered (NO2, NH2, H, COOH,\nOH) lead to similar scattering of the electrons. The adsorption of a single\nmolecule suppresses one of the two available channels of the CNT at low bias\nconductance. If more molecules are adsorbed on the same sublattice, the\nremaining open channel can be blocked or not, depending on the relative\nposition of the adsorbates. If a simple geometric condition is fulfilled this\nchannel is still open, even after adsorbing an arbitrary number of molecules.",
        "positive": "Nuclear Spin Diffusion Mediated by Heavy Hole Hyperfine Non-Collinear\n  Interactions: We show that the hyperfine mediated dynamics of heavy hole states confined in\nneutral self- assembled quantum dots leads to a nuclear spin diffusion\nmechanism. It is found that the oftentimes neglected effective heavy hole\nhyperfine non-collinear interaction is responsible for the low degree of\nnuclear spin polarization in neutral quantum dots. Moreover, our results\ndemonstrate that after pumping the nuclear spin state is left in a complex\nmixed state, from which it is not straightforward to deduce the sign of the\nIsing-like interactions."
    },
    {
        "anchor": "Polaritonic analogue of Datta and Das spin transistor: We propose the scheme of a novel spin-optronic device, optical analog of\nDatta and Das spin transistor for the electrons. The role of the\nferromagnetic-nonmagnetic contact is played by a spatially confined cavity\npolariton BEC. The condensate is responsible for the appearance of effective\nmagnetic field which rotates the spin state of a propagating pulse of\npolaritons allowing to tune the transmittivity of the device.",
        "positive": "Electronic Properties of Carbon Nanostructures: The carbon nanostructures are perspective materials for the future\napplications. This has two reasons: first, the hexagonal atomic structure which\nenables a high molecular variability by placing different kinds of the defects\nand second, good electronic properties which can be modified for the purpose of\nthe concrete applications with the help of the defects and of the chemical\ningredients. A lot of kinds of the nanostructures was investigated. Here, the\nproperties of less common forms will be examined - the graphitic nanocone and\ngraphitic wormhole."
    },
    {
        "anchor": "Electron Beam Supercollimation in Graphene Superlattices: Although electrons and photons are intrinsically different, importing useful\nconcepts in optics to electronics performing similar functions has been\nactively pursued over the last two decades. In particular, collimation of an\nelectron beam is a long-standing goal. We show that ballistic propagation of an\nelectron beam with virtual no spatial spreading or diffraction, without a\nwaveguide or external magnetic field, can be achieved in graphene under an\nappropriate class of experimentally feasible one-dimensional external periodic\npotentials. The novel chiral quasi-one-dimensional metallic state that the\ncharge carriers are in originates from a collapse of the intrinsic helical\nnature of the charge carriers in graphene owing to the superlattice potential.\nBeyond providing a new way to constructing chiral one-dimensional states in two\ndimensions, our findings should be useful in graphene-based electronic devices\n(e.g., for information processing) utilizing some of the highly developed\nconcepts in optics.",
        "positive": "Enabling valley selective exciton scattering in monolayer WSe$_2$\n  through upconversion: Excitons, Coulomb bound electron-hole pairs, are composite bosons and their\ninteractions in traditional semiconductors lead to condensation and light\namplification. The much stronger Coulomb interaction in transition metal\ndichalcogenides such as WSe$_2$ monolayers combined with the presence of the\nvalley degree of freedom is expected to provide new opportunities for\ncontrolling excitonic effects. But so far the bosonic character of exciton\nscattering processes remains largely unexplored in these two-dimensional (2D)\nmaterials. Here we show that scattering between B-excitons and A-excitons\npreferably happens within the same valley in momentum space. This leads to\npower dependent, negative polarization of the hot B-exciton emission. We use a\nselective upconversion technique for efficient generation of B-excitons in the\npresence of resonantly excited A-excitons at lower energy, we also observe the\nexcited A-excitons state $2s$. Detuning of the continuous wave, low power laser\nexcitation outside the A-exciton resonance (with a full width at half maximum\nof 4 meV) results in vanishing upconversion signal."
    },
    {
        "anchor": "Full Counting Statistics as the Geometry of Two Planes: Provided the measuring time is short enough, the full counting statistics\n(FCS) of the charge pumped across a barrier as a result of a series of voltage\npulses are shown to be equivalent to the geometry of two planes. This\nformulation leads to the FCS without the need for the usual non-equilibrium\n(Keldysh) transport theory or the direct computation of the determinant of an\ninfinite-dimensional matrix. In the particular case of the application of N\nLorentzian pulses, we show the computation of the FCS reduces to the\ndiagonalization of an N x N matrix. We also use the formulation to compute the\ncore-hole response in the X-ray edge problem and the FCS for a square wave\npulse-train for the case of low transmission.",
        "positive": "Microcavity design for low threshold polariton condensation with\n  ultrashort optical pulse excitation: We present a microcavity structure with a shifted photonic stop-band to\nenable efficient non-resonant injection of a polariton condensate with\nspectrally broad femtosecond pulses. The concept is demonstrated theoretically\nand confirmed experimentally for a planar GaAs/AlGaAs multilayer\nheterostructure pumped with ultrashort near-infrared pulses while\nphotoluminescence is collected to monitor the optically injected polariton\ndensity. As the excitation wavelength is scanned, a regime of polariton\ncondensation can be reached in our structure at a consistently lower fluence\nthreshold than in a state-of-the-art conventional microcavity. Our microcavity\ndesign improves the polariton injection efficiency by a factor of 4, as\ncompared to a conventional microcavity design, when broad excitation pulses are\ncentered at a wavelength of 740 nm. Most remarkably, this improvement factor\nreaches 270 when the excitation wavelength is centered at 750 nm."
    },
    {
        "anchor": "The enigma of the nu=0 quantum Hall effect in graphene: We apply Laughlin's gauge argument to analyze the $\\nu=0$ quantum Hall effect\nobserved in graphene when the Fermi energy lies near the Dirac point, and\nconclude that this necessarily leads to divergent bulk longitudinal resistivity\nin the zero temperature thermodynamic limit. We further predict that in a\nCorbino geometry measurement, where edge transport and other mesoscopic effects\nare unimportant, one should find the longitudinal conductivity vanishing in all\ngraphene samples which have an underlying $\\nu=0$ quantized Hall effect. We\nargue that this $\\nu=0$ graphene quantum Hall state is qualitatively similar to\nthe high field insulating phase (also known as the Hall insulator) in the\nlowest Landau level of ordinary semiconductor two-dimensional electron systems.\nWe establish the necessity of having a high magnetic field and high mobility\nsamples for the observation of the divergent resistivity as arising from the\nexistence of disorder-induced density inhomogeneity at the graphene Dirac\npoint.",
        "positive": "Topological suppression of magnetoconductance oscillations in NS\n  junctions: We show that the magnetoconductance oscillations of laterally-confined 2D NS\njunctions are completely suppressed when the superconductor side enters a\ntopological phase. This suppression can be attributed to the modification of\nthe vortex structure of local currents at the junction caused by the\ntopological transition of the superconductor. The two regimes (with and without\noscillations) could be seen in a semiconductor 2D junction with a cleaved-edge\ngeometry, one of the junction arms having proximitized superconductivity. We\npredict similar oscillations and suppression as a function of the Rashba\ncoupling. The oscillation suppression is robust against differences in chemical\npotential and phases of lateral superconductors."
    },
    {
        "anchor": "Wannier-Bloch approach to localization in high harmonics generation in\n  solids: Emission of high-order harmonics from solids provides a new avenue in\nattosecond science. On one hand, it allows to investigate fundamental processes\nof the non-linear response of electrons driven by a strong laser pulse in a\nperiodic crystal lattice. On the other hand, it opens new paths toward\nefficient attosecond pulse generation, novel imaging of electronic wave\nfunctions, and enhancement of high-order harmonic generation (HHG) intensity. A\nkey feature of HHG in a solid (as compared to the well-understood phenomena of\nHHG in an atomic gas) is the delocalization of the process, whereby an electron\nionized from one site in the periodic lattice may recombine with any other.\nHere, we develop an analytic model, based on the localized Wannier wave\nfunctions in the valence band and delocalized Bloch functions in the conduction\nband. This Wannier-Bloch approach assesses the contributions of individual\nlattice sites to the HHG process, and hence addresses precisely the question of\nlocalization of harmonic emission in solids. We apply this model to investigate\nHHG in a ZnO crystal for two different orientations, corresponding to wider and\nnarrower valence and conduction bands, respectively. Interestingly, for\nnarrower bands, the HHG process shows significant localization, similar to\nharmonic generation in atoms. For all cases, the delocalized contributions to\nHHG emission are highest near the band-gap energy. Our results pave the way to\ncontrolling localized contributions to HHG in a solid crystal, with hard to\noverestimate implications for the emerging area of atto-nanoscience.",
        "positive": "Generation of entangled photons in graphene in a strong magnetic field: Entangled photon states attract tremendous interest as the most vivid\nmanifestation of nonlocality of quantum mechanics and also for emerging\napplications in quantum information. Here we propose a mechanism of generation\nof polarization-entangled photons, which is based on the nonlinear optical\ninteraction (four-wave mixing) in graphene placed in a magnetic field. Unique\nproperties of quantized electron states in a magnetized graphene and optical\nselection rules near the Dirac point give rise to a giant optical nonlinearity\nand a high rate of photon production in the mid/far-infrared range."
    },
    {
        "anchor": "Non-equilibrium thermoelectric transport across normal metal-Quantum\n  dot-Superconductor hybrid system within the Coulomb blockade regime: A detailed investigation of the non-equilibrium steady-state electric and\nthermoelectric transport properties of a quantum dot coupled to the normal\nmetallic and s-wave superconducting reservoirs (N-QD-S) are provided within the\nCoulomb blockade regime. Using non-equilibrium Keldysh Green's function\nformalism, initially, various model parameter dependence of thermoelectric\ntransport properties are analysed within the linear response regime. It is\nobserved that the single-particle tunnelling close to the superconducting gap\nedge can generate a relatively large thermopower and figure of merit. Moreover,\nthe Andreev tunnelling plays a significant role in the suppression of\nthermopower and figure of merit within the gap region. Further, within the\nnon-linear regime, we discuss two different situations, i.e., the finite\nvoltage biasing between isothermal reservoirs and the finite thermal gradient\nin the context of thermoelectric heat engine. In the former case, it is shown\nthat the sub-gap Andreev heat current can become finite beyond the linear\nresponse regime and play a vital role in asymmetric heat dissipation and\nthermal rectification effect for low voltage biasing. The rectification of heat\ncurrent is enhanced for strong on-dot Coulomb interaction and at low background\nthermal energy. In the latter case, we study the variation of thermovoltage,\nthermopower, maximum power output, and corresponding efficiency with the\napplied thermal gradient. These results illustrate that hybrid\nsuperconductor-quantum dot nanostructures are promising candidatess for\nlow-temperature thermal applications.",
        "positive": "Signatures of Fractional Quantum Anomalous Hall States in Twisted MoTe2\n  Bilayer: The interplay between spontaneous symmetry breaking and topology can result\nin exotic quantum states of matter. A celebrated example is the quantum\nanomalous Hall (QAH) state, which exhibits an integer quantum Hall effect at\nzero magnetic field thanks to its intrinsic ferromagnetism. In the presence of\nstrong electron-electron interactions, exotic fractional-QAH (FQAH) states at\nzero magnetic field can emerge. These states could host fractional excitations,\nincluding non-Abelian anyons - crucial building blocks for topological quantum\ncomputation. Flat Chern bands are widely considered as a desirable venue to\nrealize the FQAH state. For this purpose, twisted transition metal\ndichalcogenide homobilayers in rhombohedral stacking have recently been\npredicted to be a promising material platform. Here, we report experimental\nsignatures of FQAH states in 3.7-degree twisted MoTe2 bilayer. Magnetic\ncircular dichroism measurements reveal robust ferromagnetic states at\nfractionally hole filled moir\\'e minibands. Using trion photoluminescence as a\nsensor, we obtain a Landau fan diagram which shows linear shifts in carrier\ndensities corresponding to the v=-2/3 and -3/5 ferromagnetic states with\napplied magnetic field. These shifts match the Streda formula dispersion of\nFQAH states with fractionally quantized Hall conductance of -2/3$e^2/h$ and\n-3/5$e^2/h$, respectively. Moreover, the v=-1 state exhibits a dispersion\ncorresponding to Chern number -1, consistent with the predicted QAH state. In\ncomparison, several non-ferromagnetic states on the electron doping side do not\ndisperse, i.e., are trivial correlated insulators. The observed topological\nstates can be further electrically driven into topologically trivial states.\nOur findings provide clear evidence of the long-sought FQAH states, putting\nforward MoTe2 moir\\'e superlattices as a fascinating platform for exploring\nfractional excitations."
    },
    {
        "anchor": "Electron-phonon relaxation in a model of a granular film: We study the electron-phonon relaxation in the model of a granular metal\nfilm, where the grains are formed by regularly arranged potential barriers of\narbitrary transparency. The relaxation rate of Debye acoustic phonons is\ncalculated, taking into account two mechanisms of electron-phonon scattering:\nthe standard Fr\\\"ohlich interaction of the lattice deformation with the\nelectron density and the interaction mediated by the displacement of grain\nboundaries dragged by the lattice vibration. At the lowest temperatures, the\nelectron-phonon cooling power follows the power-law temperature dependence\ntypical for clean systems but with the prefactor growing as the transparency of\nthe grain boundaries decreases.",
        "positive": "Anomalous Ballistic Transport in Disordered Bilayer Graphene: Dimer\n  Vacancies induced Dirac Semimetal: We report anomalous quantum transport features in bilayer graphene in\npresence of a random distribution of structural vacancies. By using an\nefficient real-space Kubo-Greenwood transport methodology, the impact of a\nvarying density of dimer versus non-dimer vacancies is investigated in very\nlarge scale disordered models. While non-dimer vacancies are shown to induce\nlocalization regimes, dimer vacancies result in an unexpected ballistic regime\nwhose energy window surprisingly enlarges with increasing impurity density.\nSuch counterintuitive phenomenon is explained by the formation of an effective\nlinear dispersion in the bilayer bandstructure, which roots in the symmetry\nbreaking effects driven by dimer vacancies, and provides a novel realization of\nDirac semimetals in high dimension."
    },
    {
        "anchor": "Quantum thermodynamics in a single-electron box: This chapter provides an overview of the methods and results for quantum\nthermodynamic experiments with single-electron devices. The experiments with a\nsingle-electron box on Jarzynski equality and Crooks relation, two-temperature\nfluctuation relations, and Maxwell's demon performed over the past few years\nare reviewed here. We further review the first experimental realization of an\nautonomous Maxwell's demon using a single-electron box as the demon.",
        "positive": "Effects of Contact Parameters on Transmission through a Benzene Ring: Transmission through a benzene ring, connected by sulfur contact atoms to\ngold leads, is calculated by a tight-binding model by means of the\nrenormalization method. Attention is focused on the parameters associated with\nthe contact atoms, namely their site energy and their bond energies with the\nring and the leads. These parameters are found to have significant effects on\nthe transmission probability function."
    },
    {
        "anchor": "Graphene nanoribbons: relevance of etching process: Most graphene nanoribbons in the experimental literature are patterned using\nplasma etching. Various etching processes induce different types of defects and\ndo not necessarily result in the same electronic and structural ribbon\nproperties. This study focuses on two frequently used etching techniques,\nnamely oxygen plasma ashing and oxygen/argon reactive ion etching (RIE). Oxygen\nplasma ashing represents an alternative to RIE physical etching for sensitive\nsubstrates, as it is a more gentle chemical process. We find that plasma ashing\ncreates defective graphene in the exposed trenches, resulting in instabilities\nin the ribbon transport. These are probably caused by more or larger localized\nstates at the edges of the ashed device compared to the RIE defined device.",
        "positive": "Ferromagnetism in ABC-trilayer graphene: In this article we study the ferromagnetic behavior of ABC-stacked trilayer\ngraphene. This is done using a nearest-neighbor tight-binding model, in the\npresence of long-range Coulomb interactions. For a given electron-electron\ninteraction g and doping level n, we determine whether the total energy is\nminimized for a paramagnetic or ferromagnetic configuration of our variational\nparameters. The g versus n phase diagram is first calculated for the unscreened\ncase. We then include the effects of screening using a simplified expression\nfor the fermion bubble diagram. We show that ferromagnetism in ABC-trilayer\ngraphene is more robust than in monolayer, in bilayer, and in ABA-trilayer\ngraphene. Although the screening reduces the ferromagnetic regime in\nABC-trilayer graphene, the critical doping level remains one order of magnitude\nlarger than in unscreened bilayer graphene."
    },
    {
        "anchor": "Carbon nanotube array as a van der Waals two-dimensional hyperbolic\n  material: We use an ab-initio approach to design and study a novel two-dimensional\nmaterial - a planar array of carbon nanotubes separated by an optimal distance\ndefined by the van der Waals interaction. We show that the energy spectrum for\nan array of quasi-metallic nanotubes is described by a strongly anisotropic\nhyperbolic dispersion and formulate a model low-energy Hamiltonian for its\nsemi-analytical treatment. Periodic-potential-induced lifting of the valley\ndegeneracy for an array of zigzag narrow-gap nanotubes leads to the band gap\ncollapse. In contrast, the band gap is opened in an array of gapless armchair\ntubes. These unusual spectra, marked by pronounced van Hove singularities in\nthe low-energy density of states, open the opportunity for interesting physical\neffects and prospective optoelectronic applications.",
        "positive": "Mapping quantum Hall edge states in graphene by scanning tunneling\n  microscopy: Quantum Hall edge states are the paradigmatic example of the bulk-boundary\ncorrespondence. They are prone to intricate reconstructions calling for their\ndetailed investigation at high spatial resolution. Here, we map quantum Hall\nedge states of monolayer graphene at a magnetic field of 7 T with scanning\ntunneling microscopy. The graphene sample features a gate-tunable lateral\ninterface between areas of different filling factor. We compare the results\nwith detailed tight-binding calculations quantitatively accounting for the\nperturbation by the tip-induced quantum dot. We find that the edge state\npattern is mapped with little perturbation by adequate choice of gate voltage.\nWe observe extended compressible regions, the antinodal structure of edge\nstates and their meandering along the lateral interface."
    },
    {
        "anchor": "Quantum interference effects in chemical vapor deposited graphene: We report several quantum interference effects in graphene grown by chemical\nvapor deposition. A crossover between weak localization and weak\nantilocalization effects is observed when varying the gate voltage and we\ndiscuss the underlying scattering mechanisms. The characteristic length scale\nfor phase coherence is compared with that estimated from universal conductance\nfluctuations in the microporeformed graphene sample. These extensive\ntemperature- and gate-dependent measurements of the intervalley and intravalley\nscattering lengths provide important and useful insight for the macroscopic\napplications of graphene-based quantum devices.",
        "positive": "Lifetimes of Confined Optical Phonons and the Shape of a Raman Peak in\n  Disordered Nanoparticles: I. Analytical Treatment: Microscopic description of Raman spectra in nanopowders of nonpolar crystals\nis accomplished by developing the theory of disorder-induced broadening of\noptical vibrational eigenmodes. Analytical treatment of this problem is\nperformed, and line shape and width are determined as functions of phonon\nquantum numbers, nanoparticle shape, size, and the strength of disorder. The\nresults are found to be strongly dependent on either the broadened line is\nseparated or it is overlapped with other lines of the spectrum. Three models of\ndisorder, i.e. weak point-like impurities, weak smooth random potential and\nstrong rare impurities are investigated in details. The possibility to form the\nphonon-impurity bound state is also studied."
    },
    {
        "anchor": "Numerical analysis of the spin-orbit coupling parameters in III-V\n  quantum wells using 8-band Kane model and finite-difference method: By means the envelope function approximation, 8-band Kane model and a\nfinite-difference scheme with the coordinate space discretization, we\nnumerically performed calculations of the spin-orbit coupling parameters for 2D\nelectron gas confined in both symmetric and asymmetric [0 0 1] quantum wells\nbased on zinc-blende III-V semiconductors. Influence of the quantum well band\nparameters and width as well as the magnitude of the external electric field\napplied along the growth direction on the Dresselhaus and Rashba spin-orbit\ncoupling parameters is investigated. It has been found that in the symmetric\nInGaAs/GaAs quantum wells linear-in-momentum spin-orbit coupling disappears for\nthe third electron subband at certain values of well width and the indium\ncontent. It is also shown that in asymmetric InGaAs/GaAs structures the\nspin-orbit coupling parameters can be equal at a certain electric field that is\nthe condition for the realization of the SU(2) spin symmetry and formation of\npersistent spin helices. Besides, we calculated the spin-orbit coupling in the\npersistent spin helix regime as a function of the well width, indium content\nand external field. The proposed approach for the calculation of the spin-orbit\ncoupling parameters can be applied to other 2D structures with the spin-orbit\ncoupling.",
        "positive": "Viscous flow through a finite-width slit: Boundary conditions and\n  dissipation: We study the hydrodynamic viscous electronic transport in a two-dimensional\nsample separated into two semi-infinite planes by a one-dimensional infinite\nbarrier. The semi-infinite planes are electrically connected via the\nfinite-size slit in the barrier. We calculate the current through the slit\nassuming finite voltage drop between the planes and neglecting disorder-induced\nOhmic resistance, so that dissipation and resistance are purely\nviscosity-induced. We find that the only solution to the Stokes equation in\nthis geometry, which yields a finite dissipation at finite resistance (and,\nhence, is not self-contradictory), is the one that fulfills both the no-stress\nand no-slip boundary conditions simultaneously. As a remarkable consequence,\nthe obtained velocity profile satisfies the so-called \"partial-slip\" (Maxwell)\nboundary condition for any value of the slip length, which drops out from all\nfinal results. We also calculate the electronic temperature profile for the\nsmall and large heat conductivity, and find asymmetric (with respect to the\nbarrier) temperature patterns in the former case."
    },
    {
        "anchor": "Cyclotron effect on coherent spin precession of two-dimensional\n  electrons: We investigate the spin dynamics of high-mobility two-dimensional electrons\nin GaAs/AlGaAs quantum wells grown along the $[001]$ and $[110]$ directions by\ntime-resolved Faraday rotation at low temperatures. In measurements on the\n$(001)$-grown structures without external magnetic fields, we observe coherent\noscillations of the electron spin polarization about the effective spin-orbit\nfield. In non-quantizing magnetic fields applied normal to the sample plane,\nthe cyclotron motion of the electrons rotates the effective spin-orbit field.\nThis rotation leads to fast oscillations in the spin polarization about a\nnon-zero value and a strong increase in the spin dephasing time in our\nexperiments. These two effects are absent in the $(110)$-grown structure due to\nthe different symmetry of its effective spin-orbit field. The measurements are\nin excellent agreement with our theoretical model.",
        "positive": "Novel hyperbolic metamaterials based on multilayer graphene structures: We suggest a new class of hyperbolic metamaterials for THz frequencies based\non multilayer graphene structures. We calculate the dielectric permittivity\ntensor of the effective nonlocal medium with a periodic stack of graphene\nlayers and demonstrate that tuning from elliptic to hyperbolic dispersion can\nbe achieved with an external gate voltage. We reveal that such graphene\nstructures can demonstrate a giant Purcell effect that can be used for boosting\nthe THz emission in semiconductor devices. Tunability of these structures can\nbe enhanced further with an external magnetic field which leads to the\nunconventional hybridization of the TE and TM polarized waves."
    },
    {
        "anchor": "Study of the magnetoelastic effect in nickel and cobalt thin films at\n  GHz range using X-ray microscopy: We use surface acoustic waves of 1 and 3 GHz in hybrid piezoelectric-magnetic\nsystems with either cobalt or nickel as a magnetic layer to generate\nmagnetoacoustic waves and directly image them using stroboscopic X-ray magnetic\ncircular dichroism imaging. Our measurements visualize and quantify the\namplitudes of both acoustic and magnetic components of the magnetoacoustic\nwaves, which are generated in the ferromagnetic layer and can propagate over\nmillimeter distances. Additionally, we quantifiedy the magnetoelastic strain\ncomponent for cobalt and nickel through micromagnetic simulations. We obtained\na drop in the magnetoacoustic signal at 3 GHz suggesting a speed limit for the\nefficient magnetoelastic coupling in our hybrid devices.",
        "positive": "Coherent Interlayer Tunneling and Negative Differential Resistance with\n  High Current Density in Double Bilayer Graphene-WSe2 Heterostructures: We demonstrate gate-tunable resonant tunneling and negative differential\nresistance between two rotationally aligned bilayer graphene sheets separated\nby bilayer WSe2. We observe large interlayer current densities of 2 uA/um2 and\n2.5 uA/um2, and peak-to-valley ratios approaching 4 and 6 at room temperature\nand 1.5 K, respectively, values that are comparable to epitaxially grown\nresonant tunneling heterostructures. An excellent agreement between theoretical\ncalculations using a Lorentzian spectral function for the two-dimensional (2D)\nquasiparticle states, and the experimental data indicates that the interlayer\ncurrent stems primarily from energy and in-plane momentum conserving 2D-2D\ntunneling, with minimal contributions from inelastic or non-momentum-conserving\ntunneling. We demonstrate narrow tunneling resonances with intrinsic\nhalf-widths of 4 and 6 meV at 1.5 K and 300 K, respectively."
    },
    {
        "anchor": "Scenario for Fractional Quantum Hall Effect in Bulk Isotropic Materials: We investigate the possibility of a strongly correlated Fractional Quantum\nHall (FQH) state in bulk three dimensional isotropic (not layered) materials.\nWe find that a FQH state can exist at low densities only if it is accompanied\nby a staging transition in which the electrons re-organize themselves in\nlayers, perpendicular to the magnetic field, at distances of order the magnetic\nlength apart. The Hartree energy associated to the staging transition is\noff-set by the correlation Fock energy of the 3D FQH state. We obtain the phase\ndiagram of bulk electrons in a magnetic field subject to Coulomb interactions\nas a function of carrier density and lattice constant. At very low densities,\nthe 3D FQH state exhibits a transition to a 3D Wigner crystal state stabilized\nby phonon correlations.",
        "positive": "Emissivity measurements with an Atomic Force Microscope: We show that functionalized micromechanical bilayer levers can be used as\nsensitive probes to accurately measure radiative heat flux in vacuum between\ntwo materials at the micro scale. By means of calibration to one material these\nmeasurements can be made quantitative for radiative heat flux or for either\ntemperature or material emissivity. We discuss issues and opportunities for our\nmethod and provide ample technical details regarding its implementation and\ndemonstrate good correspondence with the Stefan Boltzman law. We use this\nsystem to probe the phase transition of VO2 and find that radiative heat\ntransfer in farfield between VO2 and glass can be reversibly modulated by a\nfactor of 5."
    },
    {
        "anchor": "Valley Hall effect caused by the phonon and photon drag: Valley Hall effect is an appearance of the valley current in the direction\ntransverse to the electric current. We develop the microscopic theory of the\nvalley Hall effect in two-dimensional semiconductors where the electrons are\ndragged by the phonons or photons. We derive and analyze all relevant\ncontributions to the valley current including the skew-scattering effects\ntogether with the anomalous contributions caused by the side-jumps and the\nanomalous velocity. The partial compensation of the anomalous contributions is\nstudied in detail. The role of two-phonon and two-impurity scattering processes\nis analyzed. We also compare the valley Hall effect under the drag conditions\nand the valley Hall effect caused by the external static electric field.",
        "positive": "Evanescent channels and scattering in cylindrical nanowire\n  heterostructures: We investigate the scattering phenomena produced by a general finite-range\nnonseparable potential in a multi-channel two-probe cylindrical nanowire\nheterostructure. The multi-channel current scattering matrix is efficiently\ncomputed using the R-matrix formalism extended for cylindrical coordinates.\nConsidering the contribution of the evanescent channels to the scattering\nmatrix, we are able to put in evidence the specific dips in the tunneling\ncoefficient in the case of an attractive potential. The cylindrical symmetry\ncancels the \"selection rules\" known for Cartesian coordinates. If the\nattractive potential is superposed over a non-uniform potential along the\nnanowire, then resonant transmission peaks appear. We can characterize them\nquantitatively through the poles of the current scattering matrix. Detailed\nmaps of the localization probability density sustain the physical\ninterpretation of the resonances (dips and peaks). Our formalism is applied to\na variety of model systems like a quantum dot, a core/shell quantum ring or a\ndouble-barrier, embedded into the nanocylinder."
    },
    {
        "anchor": "Spin-charge coupled transport in van der Waals systems with random\n  tunneling: We study the electron and spin transport in a van der Waals system formed by\none layer with strong spin-orbit coupling and a second layer without spin-orbit\ncoupling, in the regime when the interlayer tunneling is random. We find that\nin the layer without intrinsic spin-orbit coupling spin-charge coupled\ntransport can be induced by two distinct mechanisms. First, the gapless\ndiffusion modes of the two isolated layers hybridize in the presence of\ntunneling, which constitutes a source of spin-charge coupled transport in the\nsecond layer. Second, the random tunneling introduces spin-orbit coupling in\nthe effective disorder-averaged single-particle Hamiltonian of the second\nlayer. This results in non-trivial spin transport and, for sufficiently strong\ntunneling, in spin-charge coupling. As an example, we consider a van der Waals\nsystem formed by a two-dimensional electron gas (2DEG)--such as graphene--and\nthe surface of a topological insulator (TI) and show that the proximity of the\nTI induces a coupling of the spin and charge transport in the 2DEG. In\naddition, we show that such coupling can be tuned by varying the doping of the\nTI's surface. We then obtain, for a simple geometry, the current-induced\nnon-equilibrium spin accumulation (Edelstein effect) caused in the 2DEG by the\ncoupling of charge and spin transport.",
        "positive": "Repulsive Casimir force between Weyl semimetals: Weyl semimetals are a class of topological materials that exhibit a bulk Hall\neffect due to time-reversal symmetry breaking. We show that for the idealized\nsemi-infinite case, the Casimir force between two identical Weyl semimetals is\nrepulsive at short range and attractive at long range. Considering plates of\nfinite thickness, we can reduce the size of the long-range attraction even\nmaking it repulsive for all distances when thin enough. In the thin-film limit,\nwe study the appearance of an attractive Casimir force at shorter distances due\nto the longitudinal conductivity. Magnetic field, thickness, and chemical\npotential provide tunable nobs for this effect, controlling the Casimir force:\nwhether it is attractive or repulsive, the magnitude of the effect, and the\npositions and existence of a trap and antitrap."
    },
    {
        "anchor": "Interrogating Quantum Nonlocal Effects in Nanoplasmonics through\n  Electron-Beam Spectroscopy: A rigorous account of quantum nonlocal effects is paramount for understanding\nthe optical response of metal nanostructures and for designing plasmonic\ndevices at the nanoscale. Here, we present a scheme for retrieving the quantum\nsurface response of metals, encapsulated in the Feibelman $d$-parameters, from\nelectron energy-loss spectroscopy (EELS) and cathodoluminescence (CL)\nmeasurements. We theoretically demonstrate that quantum nonlocal effects have a\ndramatic impact on EELS and CL spectra, in the guise of spectral shifts and\nnonlocal damping, when either the system size or the inverse wave vector in\nextended structures approach the nanometer scale. Our concept capitalizes on\nthe unparalleled ability of free-electrons to supply deeply subwavelength\nnear-fields and, thus, probe the optical response of metals at length scales in\nwhich quantum-mechanical effects are apparent. These results pave the way for a\nwidespread use of the $d$-parameter formalism, thereby facilitating a rigorous\nyet practical inclusion of nonclassical effects in nanoplasmonics.",
        "positive": "Chiral symmetry and fermion doubling in the zero-mode Landau levels of\n  massless Dirac fermions with disorder: The effect of disorder on the Landau levels of massless Dirac fermions is\nexamined for the cases with and without the fermion doubling. To tune the\ndoubling a tight-binding model having a complex transfer integral is adopted to\nshift the energies of two Dirac cones, which is theoretically proposed earlier\nand realizable in cold atoms in an optical lattice. In the absence of the\nfermion doubling, the $n=0$ Landau level is shown to exhibit an anomalous\nsharpness even if the disorder is uncorrelated in space (i.e., large K-K'\nscattering). This anomaly occurs when the disorder respects the chiral symmetry\nof the Dirac cone."
    },
    {
        "anchor": "Long-Range Charge Transport in Homogeneous and Alternating-Rigidity\n  Chains: We study the interplay of intrinsic-electronic and environmental factors on\nlong-range charge transport across molecular chains with up to $N\\sim 80$\nmonomers. We describe the molecular electronic structure of the chain with a\ntight-binding Hamiltonian. Thermal effects in the form of electron decoherence\nand inelastic scatterings are incorporated with the Landauer-B\\\"uttiker probe\nmethod. In short chains of up to 10 units we observe the crossover between\ncoherent (tunneling, ballistic) motion and thermally-assisted conduction, with\nthermal effects enhancing the current beyond the quantum coherent limit. We\nfurther show that unconventional (non monotonic with size) transport behavior\nemerges when monomer-to-monomer electronic coupling is made large. In long\nchains, we identify a different behavior, with thermal effects suppressing the\nconductance below the coherent-ballistic limit. With the goal to identify a\nminimal model for molecular chains displaying unconventional and effective\nlong-range transport, we simulate a modular polymer with alternating regions of\nhigh and low rigidity. Simulations show that, surprisingly, while charge\ncorrelations are significantly affected by structuring environmental\nconditions, reflecting charge delocalization, the electrical resistance\ndisplays an averaging effect, and it is not sensitive to this patterning. We\nconclude by arguing that efficient long-range charge transport requires\nengineering both internal electronic parameters and environmental conditions.",
        "positive": "Electronic orbital angular momentum and magnetism of graphene: Orbital angular momentum (OAM) of graphene electrons in a perpendicular\nmagnetic field is calculated and corresponding magnetic moment is used to\ninvestigate the magnetism of perfect graphene. Variation in magnetization\ndemonstrates its decrease with carrier-doping, plateaus in a large field, and\nde Haas-van Alphen oscillation. Regulation of magnetism by a parallel electric\nfield is presented. The OAM originates from atomic-scale electronic motion in\ngraphene lattice, and vector hopping interaction between carbon atomic orbitals\nis the building element. A comparison between OAM of graphene electrons, OAM of\nDirac fermions, and total angular momentum of the latter demonstrates their\ndifferent roles in magnetism of graphene. Applicability and relation to\nexperiments of the results are discussed."
    },
    {
        "anchor": "An atomistic quantum transport solver with dephasing for field-effect\n  transistors: Extended Huckel theory (EHT) along with NEGF (Non-equilibrium Green's\nfunction formalism) has been used for modeling coherent transport through\nmolecules. Incorporating dephasing has been proposed to theoretically reproduce\nexperimental characteristics for such devices. These elastic and inelastic\ndephasing effects are expected to be important in quantum devices with the\nfeature size around 10nm, and hence an efficient and versatile solver is\nneeded. This model should have flexibility to be applied to a wide range of\nnano-scale devices, along with 3D electrostatics, for arbitrary shaped contacts\nand surface roughness. We report one such EHT-NEGF solver with dephasing by\nself-consistent Born approximation (SCBA). 3D electrostatics is included using\na finite-element scheme. The model is applied to a single wall carbon nanotube\n(CNT) cross-bar structure with a C60 molecule as the active channel. Without\ndephasing, a negative differential resistance (NDR) peak appears when the C60\nlowest unoccupied molecular orbital level crosses a van Hove singularity in the\n1D density of states of the metallic CNTs acting as contacts. This NDR\ndiminishes with increasing dephasing in the channel as expected.",
        "positive": "Magnetic warping in topological insulators: We analyze the electronic structure of topological surface states in the\nfamily of magnetic topological insulators MnBi$_{2n}$Te$_{3n+1}$. We show that,\nat natural-cleavage surfaces, the Dirac cone warping changes its symmetry from\nhexagonal to trigonal at the magnetic ordering temperature. In particular, an\nenergy splitting develops between the surface states of same band index but\nopposite surface momenta upon formation of the long-range magnetic order. As a\nconsequence, measurements of such energy splittings constitute a simple\nprotocol to detect the magnetic ordering via the surface electronic structure,\nalternative to the detection of the surface magnetic gap. Interestingly, while\nthe latter signals a nonzero surface magnetic flux, the trigonal warping\npredicted here is, in addition, sensitive to the direction of the surface\nmagnetic flux."
    },
    {
        "anchor": "Real-Space Entanglement Spectrum of Quantum Hall States: We investigate the entanglement spectra arising from sharp real-space\npartitions of the system for quantum Hall states. These partitions differ from\nthe previously utilized orbital and particle partitions and reveal\ncomplementary aspects of the physics of these topologically ordered systems. We\nshow, by constructing one to one maps to the particle partition entanglement\nspectra, that the counting of the real-space entanglement spectra levels for\ndifferent particle number sectors versus their angular momentum along the\nspatial partition boundary is equal to the counting of states for the system\nwith a number of (unpinned) bulk quasiholes excitations corresponding to the\nsame particle and flux numbers. This proves that, for an ideal model state\ndescribed by a conformal field theory, the real-space entanglement spectra\nlevel counting is bounded by the counting of the conformal field theory edge\nmodes. This bound is known to be saturated in the thermodynamic limit (and at\nfinite sizes for certain states). Numerically analyzing several ideal model\nstates, we find that the real-space entanglement spectra indeed display the\nedge modes dispersion relations expected from their corresponding conformal\nfield theories. We also numerically find that the real-space entanglement\nspectra of Coulomb interaction ground states exhibit a series of branches,\nwhich we relate to the model state and (above an entanglement gap) to its\nquasiparticle-quasihole excitations. We also numerically compute the\nentanglement entropy for the nu=1 integer quantum Hall state with real-space\npartitions and compare against the analytic prediction. We find that the\nentanglement entropy indeed scales linearly with the boundary length for large\nenough systems, but that the attainable system sizes are still too small to\nprovide a reliable extraction of the sub-leading topological entanglement\nentropy term.",
        "positive": "Iterative real-time path integral approach to nonequilibrium quantum\n  transport: We have developed a numerical approach to compute real-time path integral\nexpressions for quantum transport problems out of equilibrium. The scheme is\nbased on a deterministic iterative summation of the path integral (ISPI) for\nthe generating function of the nonequilibrium current. Self-energies due to the\nleads, being non-local in time, are fully taken into account within a finite\nmemory time, thereby including non-Markovian effects, and numerical results are\nextrapolated both to vanishing (Trotter) time discretization and to infinite\nmemory time. This extrapolation scheme converges except at very low\ntemperatures, and the results are then numerically exact. The method is applied\nto nonequilibrium transport through an Anderson dot."
    },
    {
        "anchor": "InAs-AlSb quantum wells in tilted magnetic fields: InAs-AlSb quantum wells are investigated by transport experiments in magnetic\nfields tilted with respect to the sample normal. Using the coincidence method\nwe find for magnetic fields up to 28 T that the spin splitting can be as large\nas 5 times the Landau splitting. We find a value of the g-factor of about 13.\nFor small even-integer filling factors the corresponding minima in the\nShubnikov-de Haas oscillations cannot be tuned into maxima for arbitrary tilt\nangles. This indicates the anti-crossing of neighboring Landau and spin levels.\nFurthermore we find for particular tilt angles a crossover from even-integer\ndominated Shubnikov-de Haas minima to odd-integer minima as a function of\nmagnetic field.",
        "positive": "Detecting domain wall trapping and motion at a constriction in narrow\n  ferromagnetic wires using perpendicular-current giant magnetoresistance: We present a versatile method for detecting the presence and motion of a\ntrapped domain wall in a narrow ferromagnetic layer using\ncurrent-perpendicular-to-plane (CPP) giant magnetoresistance (MR). The CPP-MR\nresponse to small motions of the trapped domain wall is enhanced because the\nCPP current is restricted to the region of wall trapping. We use a\nPermalloy/Cu/Permalloy spin valve in the shape of a long, ~500-nm-wide wire\nwith a constriction (notch) near its middle that acts as a trapping site for a\nhead-to-head domain wall. Two different notch shapes were studied, mostly at\n4.2 K but also at 295K."
    },
    {
        "anchor": "The Andreev states of a superconducting quantum dot: mean field vs exact\n  numerical results: We analyze the spectral density of a single level quantum dot coupled to\nsuperconducting leads focusing on the Andreev states appearing within the\nsuperconducting gap. We use two complementary approaches: the numerical\nrenormalization group and the Hartree-Fock approximation. Our results show the\nexistence of up to four bound states within the gap when the ground state is a\nspin doublet (\\pi\\ phase). Furthermore the results demonstrate the reliability\nof the mean field description within this phase. This is understood from a\ncomplete correspondence that can be established between the exact and the mean\nfield quasiparticle excitation spectrum",
        "positive": "Renormalized frequency shift of a Wannier exciton in a one-dimensional\n  system: The radiative frequency shift of superradiant exciton in a one-dimensional\nsystem is calculated. It is shown that a finite frequency shift can be obtained\nafter proper renormalization. The value of the shift is inversely proportional\nto the factor $\\frac{\\lambda}{d}$, where $\\lambda $ is the wavelength of the\nemitted photon and $d$ is the lattice spacing."
    },
    {
        "anchor": "Spectral and transport properties of a half-filled Anderson impurity\n  coupled to phase-biased superconducting and metallic leads: We derive and apply a general scheme for mapping a setup consisting of a\nhalf-filled single level quantum dot coupled to one normal metallic and two\nsuperconducting phase-biased leads onto an ordinary half-filled single impurity\nAnderson model with single modified tunneling density of states. The theory\nallows for the otherwise unfeasible application of the standard numerical\nrenormalization group and enables to obtain phase-dependent local spectral\nproperties as well as phase-dependent induced pairing and Josephson current.\nThe resulting transport properties match well with the numerically exact\ncontinuous-time hybridization-expansion quantum Monte Carlo. For weakly coupled\nnormal electrode, the spectral properties can be interpreted in terms of\nnormal-electrode-broadened Andreev bound states with phase-dependent position\nanalogous to the superconducting Anderson model, which coexist in the\n$\\pi$-like phase with a Kondo peak whose phase-dependent Kondo temperature\nfollows the form conjectured previously in Doma\\'nski et al., Phys.~Rev.~B {\\bf\n95}, 045104 (2017)",
        "positive": "Conservation of chirality at a junction between two Weyl semimetals: In Weyl semimetals the location of linear band crossings, the Weyl cones, is\nnot bound to any high symmetry point of the Brillouin zone, unlike the Dirac\nnodes in graphene. This flexibility is advantageous for valleytronics, where\ninformation is encoded in the valleys of the band structure when intervalley\nscattering is weak. However, if numerous Weyl cones coexist the encoded\ninformation can decohere rapidly because of band mixing. Here, we investigate\nhow the helical iso-spin texture of Weyl cones affects valleytronics in\nheterojunctions of Weyl materials, and show how the chirality of this iso-spin\ntexture can serve to encode information."
    },
    {
        "anchor": "Luttinger Liquid at the Edge of a Graphene Vacuum: We demonstrate that an undoped two-dimensional carbon plane (graphene) whose\nbulk is in the integer quantum Hall regime supports a non-chiral Luttinger\nliquid at an armchair edge. This behavior arises due to the unusual dispersion\nof the non-interacting edges states, causing a crossing of bands with different\nvalley and spin indices at the edge. We demonstrate that this stabilizes a\ndomain wall structure with a spontaneously ordered phase degree of freedom.\nThis coherent domain wall supports gapless charged excitations, and has a power\nlaw tunneling $I-V$ with a non-integral exponent. In proximity to a bulk lead,\nthe edge may undergo a quantum phase transition between the Luttinger liquid\nphase and a metallic state when the edge confinement is sufficiently strong\nrelative to the interaction energy scale.",
        "positive": "Quantum Hall Effect of Massless Dirac Fermions in a Vanishing Magnetic\n  Field: The effect of strong long-range disorder on the quantization of the Hall\nconductivity $\\sigma_{xy}$ in graphene is studied numerically. It is shown that\nincreasing Landau-level mixing progressively destroys all plateaus in\n$\\sigma_{xy}$ except the plateaus at $\\sigma_{xy}=\\mp e^2/2h$ (per valley and\nper spin). The critical state at the charge-neutral Dirac point is robust to\nstrong disorder and belongs to the universality class of the conventional\nplateau transitions in the integer quantum Hall effect. We propose that the\nbreaking of time-reversal symmetry by ripples in graphene can realize this\nquantum critical point in a vanishing magnetic field."
    },
    {
        "anchor": "Transport Characterization of the Magnetic Anisotropy of (Ga,Mn)As: The rich magnetic anisotropy of compressively strained (Ga,Mn)As has\nattracted great interest recently. Here we discuss a sensitive method to\nvisualize and quantify the individual components of the magnetic anisotropy\nusing transport. A set of high resolution transport measurements is compiled\ninto color coded resistance polar plots, which constitute a fingerprint of the\nsymmetry components of the anisotropy. As a demonstration of the sensitivity of\nthe method, we show that these typically reveal the presence of both the [-110]\nand the [010] uniaxial magnetic anisotropy component in (Ga,Mn)As layers, even\nwhen most other techniques reveal only one of these components.",
        "positive": "Optical dipole traps and atomic waveguides based on Bessel light beams: We theoretically investigate the use of Bessel light beams generated using\naxicons for creating optical dipole traps for cold atoms and atomic\nwaveguiding. Zeroth-order Bessel beams can be used to produce highly elongated\ndipole traps allowing for the study of one-dimensional trapped gases and\nrealization of a Tonks gas of impentrable bosons. First-order Bessel beams are\nshown to be able to produce tight confined atomic waveguides over centimeter\ndistances."
    },
    {
        "anchor": "Bending Strain Engineering of Spin Transport in Quantum Spin Hall\n  Systems: Topological Nano-mechanospintronics: Quantum spin Hall (QSH) system can exhibit exotic spin transport phenomena,\nmediated by its topological edge states. Here a novel concept of bending strain\nengineering to tune the spin transport properties of a QSH system is\ndemonstrated by both model and first-principles calculations. Interestingly, we\ndiscover that bending strain can be used to mitigate the spin conservation of a\nQSH system to generate a non-zero spin current (SC), meanwhile the preservation\nof time reversal symmetry renders its edge states topologically protected to\ntransport robust SC without back scattering. This novel physics mechanism can\nbe applied to effectively tune the SC and spin Hall current in a QSH system by\ncontrol of its bending curvature. Furthermore, the realization of QSH systems\nwith controllable curvature can be achieved by the concept of \"topological\nnanomechnical architecture\". Taking Bi/Cl/Si(111) as a material example, we\ndemonstrate that the relative spin orientations between two edge states of a\nBi/Cl/Si(111) film can indeed be tuned dramatically by its self-bending\nbehaviors induced by the pre-designed inherent strain. Therefore, this concept\nof \"bending strain engineering of spins\" via topological nanomechanical\narchitecture affords a promising route towards the realization of topological\nnano-mechanospintronics.",
        "positive": "Many-body current formula and current conservation for non-equilibrium\n  fully interacting nanojunctions: We consider the electron transport properties through fully interacting\nnanoscale junctions beyond the linear-response regime. We calculate the current\nflowing through an interacting region connected to two interacting leads, with\ninteraction crossing at the left and right contacts, by using a non-equilibrium\nGreen's functions (NEGF) technique. The total current at one interface (the\nleft one for example) is made of several terms which can be regrouped into two\nsets. The first set corresponds to a very generalised Landauer-like current\nformula with physical quantities defined only in the interacting central region\nand with renormalised lead self-energies. The second set characterises\ninelastic scattering events occurring in the left lead. We show how this term\ncan be negligible or even vanish due to the pseudo-equilibrium statistical\nproperties of the lead in the thermodynamic limit. The expressions for the\ndifferent Green's functions needed for practical calculations of the current\nare also provided. We determine the constraints imposed by the physical\ncondition of current conservation. The corresponding equation imposed on the\ndifferent self-energy quantities arising from the current conservation is\nderived. We discuss in detail its physical interpretation and its relation with\npreviously derived expressions. Finally several important key features are\ndiscussed in relation to the implementation of our formalism for calculations\nof quantum transport in realistic systems."
    },
    {
        "anchor": "Understanding the Bias Dependence of Low Frequency Noise in Sin-gle\n  Layer Graphene FETs: This letter investigates the bias-dependent low frequency noise of single\nlayer graphene field-effect transistors. Noise measurements have been conducted\nwith electrolyte-gated graphene transistors covering a wide range of gate and\ndrain bias conditions for different channel lengths. A new analytical model\nthat accounts for the propagation of the local noise sources in the channel to\nthe terminal currents and voltages is proposed in this paper to investigate the\nnoise bias dependence. Carrier number and mobility fluctuations are considered\nas the main causes of low frequency noise and the way these mechanisms\ncontribute to the bias dependence of the noise is analyzed in this work.\nTypically, normalized low frequency noise in graphene devices has been usually\nshown to follow an M-shape dependence versus gate voltage with the minimum near\nthe charge neutrality point (CNP). Our work reveals for the first time the\nstrong correlation between this gate dependence and the residual charge which\nis relevant in the vicinity of this specific bias point. We discuss how charge\ninhomogeneity in the graphene channel at higher drain voltages can contribute\nto low frequency noise; thus, channel regions nearby the source and drain\nterminals are found to dominate the total noise for gate biases close to the\nCNP. The excellent agreement between the experimental data and the predictions\nof the analytical model at all bias conditions confirms that the two\nfundamental 1/f noise mechanisms, carrier number and mobility fluctuations,\nmust be considered simultaneously to properly understand the low frequency\nnoise in graphene FETs. The proposed analytical compact model can be easily\nimplemented and integrated in circuit simulators, which can be of high\nimportance for graphene based circuits design.",
        "positive": "Exceptional points in classical spin dynamics: Non-conservative physical systems admit a special kind of spectral\ndegeneracy, known as exceptional point (EP), at which eigenvalues and\neigenvectors of the corresponding non-Hermitian Hamiltonian coalesce. Dynamical\nparametric encircling of the EP can lead to non-adiabatic evolution associated\nwith a state flip, a sharp transition between the resonant modes. Physical\nconsequences of the dynamical encircling of EPs in open dissipative systems\nhave been explored in optics and photonics. Building on the recent progress in\nunderstanding the parity-time (PT)-symmetric dynamics in spin systems, we use\ntopological properties of EPs to implement chiral non-reciprocal transmission\nof a spin through the material with non-uniform magnetization, like helical\nmagnet. We consider an exemplary system, spin-torque-driven single spin\ndescribed by the time-dependent non-Hermitian Hamiltonian. We show that\nencircling individual EPs in parameter space results in non-reciprocal spin\ndynamics and find the range of optimal protocol parameters for high-efficiency\nasymmetric spin filter based on this effect. Our findings offer a platform for\nnon-reciprocal spin devices for spintronics and magnonics."
    },
    {
        "anchor": "New class of small amplitude low-field magnetoresistance oscillation in\n  unidirectional lateral superlattice: Geometric resonance of Bragg-reflected\n  cyclotron orbit: We have uncovered a new class of small amplitude magnetoresistance\noscillation in unidirectional lateral superlattice (ULSL). The oscillation is\nobserved in a low-field regime, typically |B| =< 0.03 T, as small undulation on\ntop of well-known positive magnetoresistance background. Positions of maxima of\nthe oscillation shift to lower field side with the increase of the electron\nconcentration n_e roughly proportionally to n_e^{-1/2}, and also with the\nincrease of period a of ULSL samples. The oscillation is attributed to\ncommensurability between the period a and the width of open orbits originating\nfrom the miniband structure.",
        "positive": "Observation of Dirac hierarchy in three-dimensional acoustic topological\n  insulators: Dirac cones (DCs) play a pivotal role in various unique phenomena ranging\nfrom massless electrons in graphene to robust surface states in topological\ninsulators (TIs). Recent studies have theoretically revealed a full Dirac\nhierarchy comprising an eightfold bulk DC, a fourfold surface DC, and a twofold\nhinge DC, associated with a hierarchy of topological phases including\nfirst-order to third-order three-dimensional (3D) topological insulators, using\nthe same 3D base lattice. Here, we report the first experimental observation of\nthe Dirac hierarchy in 3D acoustic TIs. Using acoustic measurements, we\nunambiguously reveal that lifting of multifold DCs in each hierarchy can induce\ntwo-dimensional (2D) topological surface states with a fourfold DC in a\nfirst-order 3D TI, one-dimensional (1D) topological hinge states with a twofold\nDC in a second-order 3D TI, and zero-dimensional (0D) topological corner states\nin a third-order 3D TI. Our work not only expands the fundamental research\nscope of Dirac physics, but also opens up a new route for multidimensional\nrobust wave manipulation."
    },
    {
        "anchor": "A Method to Detect Quantum Coherent Transport in Memristive Devices: While the size of functional elements in memristors becomes of the orders of\nnano-meters or even smaller, the quantum effects in their dynamics can\nsignificantly influence their transport properties, consistent with recent\nexperimental observations of conductance quantisation in memristors. This\nrequires the development of experimentally realizable procedures to detect\nquantumness of memristors. Here we developed an experimental protocol allowing\nus to find evidence that the memristor can be in a superposition of states with\ndifferent memristivities. We simulate the nonlinearity induced in the quantum\nmemristive system via periodic projective measurements, observing how it\nmanifests itself in the emergence of additional spectral components in the\nresponse to the harmonic signal. Moreover, the response demonstrates a resonant\nbehaviour when the frequency of the projective measurements commensurates with\nthe frequency of the input. We demonstrate that observation of such harmonic\nmixing can be used as experimental evidence of quantum effects in memristors.",
        "positive": "Breakdown of topological protection due to non-magnetic edge disorder in\n  two-dimensional materials in the Quantum Spin Hall phase: We study the suppression of the conductance quantization in quantum spin Hall\nsystems by a combined effect of electronic interactions and edge disorder, that\nis ubiquitous in exfoliated and CVD grown 2D materials. We show that the\ninterplay between the electronic localized states due to edge defects and\nelectron-electron interactions gives rise to local magnetic moments, that break\ntime-reversal symmetry and the topological protection of the edge states in 2D\ntopological systems. Our results suggest that edge disorder leads to small\ndeviations of a perfect quantized conductance in short samples and to a strong\nconductance suppression in long ones. Our analysis is based on on the Kane-Mele\nmodel, an unrestricted Hubbard mean field Hamiltonian and on a self-consistent\nrecursive Green's functions technique to calculate the transport quantities."
    },
    {
        "anchor": "Phonon-dominated energy transport in purely metallic heterostructures: We use ultrafast x-ray diffraction to quantify the transport of energy in\nlaser-excited nanoscale Au/Ni bilayers. Electron transport and efficient\nelectron-phonon coupling in Ni convert the laser-deposited energy in the\nconduction electrons within a few picoseconds into a strong non-equilibrium\nbetween hot Ni and cold Au phonons at the bilayer interface. Modeling of the\nsubsequent equilibration dynamics within various two-temperature models\nconfirms that for ultrathin Au films the thermal transport is dominated by\nphonons instead of conduction electrons because of the weak electron-phonon\ncoupling in Au.",
        "positive": "Ultra-sensitive voltage-controlled skyrmion-based spintronic diode: We have designed a passive spintronic diode based on a single skyrmion\nstabilized in a magnetic tunnel junction and studied its dynamics induced by\nvoltage-controlled anisotropy (VCMA) and Dzyaloshinskii-Moriya interaction\n(VDMI). We have demonstrated that the sensitivity (rectified voltage over input\nmicrowave power) with realistic physical parameters and geometry can be larger\nthan 10 kV/W which is one order of magnitude better than diodes employing a\nuniform ferromagnetic state. Our numerical and analytical results on the VCMA\nand VDMI-driven resonant excitation of skyrmions beyond the linear regime\nreveal a frequency dependence on the amplitude and no efficient parametric\nresonance. Skyrmions with a smaller radius produced higher sensitivities,\ndemonstrating the efficient scalability of skyrmion-based spintronic diodes.\nThese results pave the way for designing passive ultra-sensitive and energy\nefficient skyrmion-based microwave detectors."
    },
    {
        "anchor": "Distinguishing trivial and topological zero energy states in long\n  nanowire junctions: The emergence of zero energy states in non-topological superconductors\nrepresents an inevitable problem that obscures the proper identification of\nzero energy Majorana bound states (MBSs) and prevents their use as\ntopologically protected qubits. In this Research Letter we investigate long\nsuperconductor-normal-superconductor junctions where trivial zero energy\nstates, robust over a large range of parameters, appear as a result of helicity\nand confinement in the normal region. We demonstrate that both equilibrium\nsupercurrents and critical currents are sensitive to variations in the length\nof the superconductor regions in the topological phase hosting MBSs, but,\nremarkably, no such length dependence exists when robust, but trivial, zero\nenergy states are present. This strikingly different response originates from\nthe non-local nature of the MBSs and we, therefore, propose it as a simple\nprotocol for distinguishing between trivial and topological zero energy states.",
        "positive": "Carrier dynamics and coherent acoustic phonons in nitride\n  heterostructures: We model generation and propagation of coherent acoustic phonons in\npiezoelectric InGaN/GaN multi-quantum wells embedded in a \\textit{pin} diode\nstructure and compute the time resolved reflectivity signal in simulated\npump-probe experiments. Carriers are created in the InGaN wells by ultrafast\npumping below the GaN band gap and the dynamics of the photoexcited carriers is\ntreated in a Boltzmann equation framework. Coherent acoustic phonons are\ngenerated in the quantum well via both deformation potential electron-phonon\nand piezoelectric electron-phonon interaction with photogenerated carriers,\nwith the latter mechanism being the dominant one. Coherent longitudinal\nacoustic phonons propagate into the structure at the sound speed modifying the\noptical properties and giving rise to a giant oscillatory differential\nreflectivity signal. We demonstrate that coherent optical control of the\ndifferential reflectivity can be achieved using a delayed control pulse."
    },
    {
        "anchor": "Energy Dissipation and Transport in Nanoscale Devices: Understanding energy dissipation and transport in nanoscale structures is of\ngreat importance for the design of energy-efficient circuits and\nenergy-conversion systems. This is also a rich domain for fundamental\ndiscoveries at the intersection of electron, lattice (phonon), and optical\n(photon) interactions. This review presents recent progress in understanding\nand manipulation of energy dissipation and transport in nanoscale solid-state\nstructures. First, the landscape of power usage from nanoscale transistors\n(~10^-8 W) to massive data centers (~10^9 W) is surveyed. Then, focus is given\nto energy dissipation in nanoscale circuits, silicon transistors, carbon\nnanostructures, and semiconductor nanowires. Concepts of steady-state and\ntransient thermal transport are also reviewed in the context of nanoscale\ndevices with sub-nanosecond switching times. Finally, recent directions\nregarding energy transport are reviewed, including electrical and thermal\nconductivity of nanostructures, thermal rectification, and the role of\nubiquitous material interfaces.",
        "positive": "Dispersionless propagation of ultra-short spin-wave pulses in ultrathin\n  yttrium iron garnet waveguides: We study experimentally the propagation of nanosecond spin-wave pulses in\nmicroscopic waveguides made of nanometer-thick yttrium iron garnet films. For\nthese studies, we use micro-focus Brillouin light scattering spectroscopy,\nwhich provides the possibility to observe propagation of the pulses with high\nspatial and temporal resolution. We show that, for most spin-wave frequencies,\ndispersion leads to broadening of the pulse by several times at propagation\ndistances of 10 micrometers. However, for certain frequency interval, the\ndispersion broadening is suppressed almost completely resulting in a\ndispersionless pulse propagation. We show that the formation of the\ndispersion-free region is caused by the competing effects of the dipolar and\nthe exchange interaction, which can be controlled by the variation of the\nwaveguide geometry. These conclusions are supported by micromagnetic\nsimulations and analytical calculations. Our findings provide a simple solution\nfor the implementation of high-speed magnonic systems that require undisturbed\npropagation of short information-carrying spin-wave pulses."
    },
    {
        "anchor": "Topological states and quantized current in helical molecules: We report a theoretical study of electron transport along helical molecules\nunder an external electric field, which is perpendicular to the helix axis of\nthe molecule. Our results reveal that the topological states could appear in\nsingle-helical molecule and double-stranded DNA in the presence of the\nperpendicular electric field. And these topological states guarantee adiabatic\ncharge pumping across the helical molecules by rotating the electric field in\nthe transverse plane and the pumped current at zero bias voltage is quantized.\nIn addition, the quantized current constitutes multiple plateaus by scanning\nthe Fermi energy as well as the bias voltage, and hold for various model\nparameters, since they are topologically protected against perturbations. These\nresults could motivate further experimental and theoretical studies in the\nelectron transport through helical molecules, and pave the way to detect\ntopological states and quantized current in the biological systems.",
        "positive": "Incorporation of a dc bias in a high-Q 3d microwave cavity: We report a technique for applying a dc bias in a 3d microwave cavity. This\nis achieved by isolating the two halves of the cavity with a dielectric and\ndirectly using them as dc electrodes. By embedding a variable capacitance diode\nin the cavity, we tune the resonant frequency with a dc voltage at room\ntemperature, demonstrating the introduction of a dc bias into the 3d cavity\nwithout compromising its high quality factor."
    },
    {
        "anchor": "Spin-Hall effect and emergent antiferromagnetic phase transition in n-Si: Spin current experiences minimal dephasing and scattering in Si due to small\nspin-orbit coupling and spin-lattice interactions is the primary source of spin\nrelaxation. We hypothesize that if the specimen dimension is of the same order\nas the spin diffusion length then spin polarization will lead to\nnon-equilibrium spin accumulation and emergent phase transition. In n-Si, spin\ndiffusion length has been reported up to 6 {\\mu}m. The spin accumulation in Si\nwill modify the thermal transport behavior of Si, which can be detected with\nthermal characterization. In this study, we report observation of spin-Hall\neffect and emergent antiferromagnetic phase transition behavior using\nmagneto-electro-thermal transport characterization. The freestanding Pd (1 nm)/\nNi80Fe20 (75 nm)/ MgO (1 nm)/ n-Si (2 micron) thin film specimen exhibits a\nmagnetic field dependent thermal transport and spin-Hall magnetoresistance\nbehavior attributed to Rashba effect. An emergent phase transition is\ndiscovered using self-heating 3omega method, which shows a diverging behavior\nat 270 K as a function of temperature similar to a second order phase\ntransition. We propose that spin-Hall effect leads to the spin accumulation and\nresulting emergent antiferromagnetic phase transition. We propose that the\nlength scale for Rashba effect can be equal to the spin diffusion length and\ntwo-dimensional electron gas is not essential for it. The emergent\nantiferromagnetic phase transition is attributed to the site inversion\nasymmetry in diamond cubic Si lattice.",
        "positive": "Time-dependent spin and transport properties of a single-molecule magnet\n  in a tunnel junction: In single-molecule magnets, the exchange between a localized spin moment and\nthe electronic background provides a suitable laboratory for studies of\ndynamical aspects of both local spin and transport properties. Here we address\nthe time evolution of a localized spin moment coupled to an electronic level in\na molecular quantum dot embedded in a tunnel junction between metallic leads.\nThe interactions between the localized spin moment and the electronic level\ngenerate an effective interaction between the spin moment at different\ninstances in time. Therefore, we show that, despite being a single-spin system,\nthere are effective contributions of isotropic Heisenberg, and anisotropic\nIsing and Dzyaloshinski-Moriya character acting on the spin moment. The\ninteractions can be controlled by gate voltage, voltage bias, the spin\npolarization in the leads, in addition to external magnetic fields. Signatures\nof the spin dynamics are found in the transport properties of the tunneling\nsystem, and we demonstrate that measurements of the spin current may be used\nfor read-out of the local spin moment orientation."
    },
    {
        "anchor": "Study of the topological Hall effect on simple models: Recently, a chirality-driven contribution to the anomalous Hall effect has\nbeen found that is induced by the Berry phase and does not directly involve\nspin-orbit coupling. In this paper, we will investigate this effect numerically\nin a two-dimensional electron gas with a simple magnetic texture model. Both\nthe adiabatic and non-adiabatic regimes are studied, including the effect of\ndisorder. By studying the transition between both regimes the discussion about\nthe correct adiabaticity criterium in the diffusive limit is clarified.",
        "positive": "Kondo induced \u03c0-phase shift of microwave photons in a circuit\n  quantum electrodynamics architecture: Mesoscopic systems constitute appealing platforms to study many-body physics\nwith light and matter degrees of freedom. The Kondo effect refers to the\nscreening of a spin-1/2 impurity by a cloud of conduction electrons, then\nforming a many-body Fermi liquid ground state. The Kondo resonance produces a\nphase shift in the transmitted electronic wave packet which depends on the\nsymmetry and nature of the many-body ground state. Theoretical calculations\nsuggest that the Kondo resonance can interact with the irradiation photon field\nand should give rise to a {\\pi}-phase shift of the photon signal in the case\nwhere the ground state is a Fermi liquid. This {\\pi}-phase shift of microwave\nphoton is driven from the Korringa-Shiba relation of quantum impurity\nFermi-liquid ground states. We report the first observation of such a\n{\\pi}-phase shift in a graphene double quantum dot within a circuit quantum\nelectrodynamics architecture where the microwave photons couple to the\npseudo-spin or charge degrees of freedom. The observed Kondo temperature TK ~\n550 mK is in agreement with DC conductance measurements. All our results\nsupport the formation of a Kondo resonance located above the Fermi level of the\nelectronic reservoirs and the occurrence of an SU(4) Fermi-liquid ground state.\nWe finally study how the Kondo-photon interactions can be tuned by inter-dot\nelectron tunnel coupling strengths. Our experimental achievements may\ncontribute to a better understanding of many-body physics in hybrid circuit\nsystems, and open up new applications in atomic thin materials from the\nlight-matter interaction."
    },
    {
        "anchor": "Gate-dependent tunneling-induced level shifts observed in carbon\n  nanotube quantum dots: We have studied electron transport in clean single-walled carbon nanotube\nquantum dots. Because of the large number of Coulomb blockade diamonds\nsimultaneously showing both shell structure and Kondo effect, we are able to\nperform a detailed analysis of tunneling renormalization effects. Thus\ndetermining the environment induced level shifts of this artificial atom. In\nshells where only one of the two orbitals is coupled strongly, we observe a\nmarked asymmetric gate-dependence of the inelastic cotunneling lines together\nwith a systematic gate dependence of the size (and shape) of the Coulomb\ndiamonds. These effects are all given a simple explanation in terms of\nsecond-order perturbation theory in the tunnel coupling.",
        "positive": "Tunneling of magnetization versus spin-phonon and spin-spin transitions\n  in LiY_0.998Ho_0.002F_4: Strong hyperfine coupling in a 0.2% Holmium doped LiYF_4 single crystal\ninduces staircaselike hysteresis loops of the magnetization at very low\ntemperatures. The field sweep rate dependence of hysteresis loops allows the\nstudy of two different regimes in the magnetic relaxation of these weakly\ncoupled magnetic moments. At slow field sweep rates, quantum tunneling of the\nmagnetization occurs at avoided level crossings in the low-energy scheme of a\nsingle ion Ho^3+. At faster sweep rates, nonequilibrated spin-phonon and\nspin-spin transitions, mediated by weak dipolar interactions, lead to\nmagnetization oscillations and additional steps."
    },
    {
        "anchor": "Competing interactions in artificial spin chains: The low-energy magnetic configurations of artificial frustrated spin chains\nare investigated using magnetic force microscopy and micromagnetic simulations.\nContrary to most studies on two-dimensional artificial spin systems where\nfrustration arises from the lattice geometry, here magnetic frustration\noriginates from competing interactions between neighboring spins. By tuning\ncontinuously the strength and sign of these interactions, we show that\ndifferent magnetic phases can be stabilized. Comparison between our\nexperimental findings and predictions from the one-dimensional Anisotropic\nNext-Nearest-Neighbor Ising (ANNNI) model reveals that artificial frustrated\nspin chains have a richer phase diagram than initially expected. Besides the\nobservation of several magnetic orders and the potential extension of this work\nto highly-degenerated artificial spin chains, our results suggest that the\nmicromagnetic nature of the individual magnetic elements allows observation of\nmetastable spin configurations.",
        "positive": "Surface acoustic wave controlled charge dynamics in a thin InGaAs\n  quantum well: We experimentally study the optical emission of a thin quantum well and its\ndynamic modulation by a surface acoustic wave (SAW). We observe a\ncharacteristic transition of the modulation from one maximum to two maxima per\nSAW cycle as the acoustic power is increased which we find in good agreement\nwith numer- ical calculations of the SAW controlled carrier dynamics. At low\nacoustic powers the carrier mobilites limit electron-hole pair dissociation,\nwhereas at high power levels the induced electric fields give rise to efficient\nacousto-electric carrier transport. The direct comparison between the\nexperimental data and the numerical simulations provide an absolute calibration\nof the local SAW phase."
    },
    {
        "anchor": "Competing effects at Pt/YIG interfaces: spin Hall magnetoresistance,\n  magnon excitations and magnetic frustration: We study the spin Hall magnetoresistance (SMR) and the magnon spin transport\n(MST) in Pt/Y3Fe5O12(YIG)-based devices with intentionally modified interfaces.\nOur measurements show that the surface treatment of the YIG film results in a\nslight enhancement of the spin-mixing conductance and an extraordinary increase\nin the efficiency of the spin-to-magnon excitations at room temperature. The\nsurface of the YIG film develops a surface magnetic frustration at low\ntemperatures, causing a sign change of the SMR and a dramatic suppression of\nthe MST. Our results evidence that SMR and MST could be used to explore\nmagnetic properties of surfaces, including those with complex magnetic\ntextures, and stress the critical importance of the non-magnetic/ferromagnetic\ninterface properties in the performance of the resulting spintronic devices.",
        "positive": "The influence of individual lattice defects on the domain structure in\n  magnetic antidot lattices: We numerically and experimentally investigate the influence of single defects\nconsisting of a missing antidot on the spin configurations in rectangular\npermalloy antidot lattices. The introduction of such lattice defects leads to\nthe nucleation of complex domain structures after the decay of a saturating\nmagnetic field. Micromagnetic simulations yield four typical domain\nconfigurations around the defect having distinct energy densities. The\nexistence of the four spin configurations is confirmed by magnetic force\nmicroscopy on antidot lattices containing individual defects."
    },
    {
        "anchor": "A two-channel model for Spin-relaxation noise: We develop a two-channel resistor model for simulating spin transport with\ngeneral applicability. Using this model, for the case of graphene as a\nprototypical material, we calculate the spin signal consistent with\nexperimental values. Using the same model we also simulate the charge and spin-\ndependent 1/f noise, both in the local and nonlocal four-probe measurement\nschemes, and identify the noise from the spin-relaxation resistances as the\nmajor source of spin-dependent 1/f noise.",
        "positive": "Excited states of exciton-polariton condensates in 2D and 1D harmonic\n  traps: We present a theoretical description of Bogolyubov-type excitations of\nexciton-polariton Bose-Einstein condensates (BECs) in semiconductor\nmicrocavities. For a typical two dimensional (2D) BEC we focus on two limiting\ncases, the weak- and strong-coupling regimes, where a perturbation theory and\nthe Thomas-Fermi approximation, respectively, are valid. We calculate\nintegrated scattering intensity spectra for probing the collective excitations\nof the condensate in both considered limits. Moreover, in relation to recent\nexperiments on optical modulation allowing localization of condensates in a\ntrap with well controlled shape and dimensions, we study the quasi-one\ndimensional (1D) motion of the BEC in microwires and report the corresponding\nBogolyubov's excitation spectrum. We show that in 1D case the characteristic\npolariton-polariton interaction constant is expressed as $g_{1}=3\\lambda\n\\mathcal{N}/(2L_{y})$ ($\\lambda $ is the 2D polariton-polaritons interaction\nparameter in the cavity, $\\mathcal{N}$ the number of the particles, and $L_{y}$\nthe wirecavity width). We reveal some interesting features for 2D and 1D\nBogolyubov spectra for both repulsive $(\\lambda >0)$ and attractive $(\\lambda\n<0)$ interaction."
    },
    {
        "anchor": "Numerical study of current distributions in finite planar Hall samples\n  with disorder: A numerical study is made of current distributions in finite-width Hall bars\nwith disorder and some theoretical observations are verified. The equilibrium\ncurrent and the Hall current are substantially different in distribution. It is\nobserved that in the Hall-plateau regime the Hall current tends to concentrate\nnear the sample edges while it diminishes on average in the sample interior as\na consequence of localization. The edge states themselves scarcely affect both\nthe equilibrium and Hall currents in the plateau regime. The sample edge\ncombines with disorder to efficiently delocalize electrons near the edge while\nthe Hall field competes with disorder to delocalize electrons in the sample\ninterior. A possible mechanism is suggested for the breakdown of the quantum\nHall effect.",
        "positive": "Disorder-induced linear magnetoresistance in Al$_2$O$_3$/SrTiO$_3$\n  heterostructures: An unsaturated linear magnetoresistance (LMR) has attracted widely attention\nbecause of potential applications and fundamental interest. By controlling\ngrowth temperature, we realized a metal-to-insulator transition in Al2O3/SrTiO3\nheterostructures. The LMR is observed in metallic samples with electron\nmobility varying over three orders of magnitude. The observed LMR cannot be\nexplained by the guiding center diffusion model even in samples with very high\nmobility. The slope of the observed LMR is proportional to Hall mobility, and\nthe crossover field, indicating a transition from quadratic (at low fields) to\nlinear (at high fields) field dependence, is proportional to the inverse Hall\nmobility. This signifies that the classical model is valid to explain the\nobserved LMR. More importantly, we develop an analytical expression according\nto the effective-medium theory that is equivalent to the classical model. And\nthe analytical expression describes the LMR data very well, confirming the\nvalidity of the classical model."
    },
    {
        "anchor": "Room-temperature giant Stark effect of single photon emitter in van der\n  Waals material: Single photon emitters (SPEs) are critical building blocks needed for quantum\nscience and technology. For practical applications, large-scale\nroom-temperature solid-state platforms are required. Color centers in layered\nhexagonal boron nitride (hBN) have recently been found to be ultra-bright and\nstable SPEs at room temperature. Yet, to scale up solid-state quantum\ninformation processing, large tuning range of single photon energy is demanded\nfor wavelength division multiplexing quantum key distribution, where\nindistinguishability is not required, and for indistinguishable single-photon\nproduction from multi-emitters. Stark effect can tune the single photon energy\nby an electric field, which however, has been achieved only at cryogenic\ntemperature so far. Here we report the first room-temperature Stark effect of\nSPEs by exploiting hBN color centers. Surprisingly, we observe a giant Stark\nshift of single photon more than 30 meV, about one order of magnitude greater\nthan previously reported in color center emitters. Moreover, for the first\ntime, the orientation of the electric permanent dipole moment in the\nsolid-state SPE is determined via angle-resolved Stark effect, revealing the\nintrinsic broken symmetries at such a color center. The remarkable Stark shift\ndiscovered here and the significant advance in understanding its atomic\nstructure pave a way towards the scalable solid-state on-chip quantum\ncommunication and computation at room temperature.",
        "positive": "Magnetic states and optical properties of single-layer carbon-doped\n  hexagonal boron nitride: We show that carbon-doped hexagonal boron nitride (h-BN) has extraordinary\nproperties with many possible applications. We demonstrate that the\nsubstitution-induced impurity states, associated with carbon atoms, and their\ninteractions dictate the electronic structure and properties of C-doped h-BN.\nFurthermore, we show that stacking of localized impurity states in small C\nclusters embedded in h-BN forms a set of discrete energy levels in the wide gap\nof h-BN. The electronic structures of these C clusters have a plethora of\napplications in optics, magneto-optics, and opto-electronics."
    },
    {
        "anchor": "Kondo effect on the surface of 3D topological insulators: Signatures in\n  scanning tunneling spectroscopy: We investigate the scattering off dilute magnetic impurities placed on the\nsurface of three-dimensional topological insulators. In the low-temperature\nlimit, the impurity moments are Kondo-screened by the surface-state electrons,\ndespite their exotic locking of spin and momentum. We determine signatures of\nthe Kondo effect appearing in quasiparticle interference (QPI) patterns as\nrecorded by scanning tunneling spectroscopy, taking into account the full\nenergy dependence of the T matrix as well as the hexagonal warping of the\nsurface Dirac cones. We identify a universal energy dependence of the QPI\nsignal at low scanning energies as the fingerprint of Kondo physics, markedly\ndifferent from the signal due to non-magnetic or static magnetic impurities.\nFinally, we discuss our results in the context of recent experimental data.",
        "positive": "Quantum Computing and Quantum Communication with Electrons in\n  Nanostructures: If the states of spins in solids can be created, manipulated, and measured at\nthe single-quantum level, an entirely new form of information processing,\nquantum computing and quantum communication, will be possible. We review our\nproposed spin-quantum dot architecture for a quantum computer and review some\nrecent results on a deterministic source of entanglement generated by coupling\nquantum dots. Addressing the feasibility of quantum communication with\nentangled electrons we consider a scattering set-up with an entangler and beam\nsplitter where the current noise exhibits bunching behavior for electronic\nsinglet states and antibunching behavior for triplet states. We show that spin\ncurrents can produce noise even in the absence of any charge currents."
    },
    {
        "anchor": "Optomagnonics in Magnetic Solids: Coherent conversion of photons to magnons, and back, provides a natural\nmechanism for rapid control of interactions between stationary spins with long\ncoherence times and high-speed photons. Despite the large frequency difference\nbetween optical photons and magnons, coherent conversion can be achieved\nthrough a three-particle interaction between one magnon and two photons whose\nfrequency difference is resonant with the magnon frequency, as in optomechanics\nwith two photons and a phonon. The large spin density of a transparent\nferromagnetic insulator (such as the ferrite yttrium iron garnet) in an optical\ncavity provides an intrinsic photon-magnon coupling strength that we calculate\nto exceed reported optomechanical couplings. A large cavity photon number and\nproperly selected cavity detuning produce a predicted effective coupling\nstrength sufficient for observing electromagnetically induced transparency and\nthe Purcell effect, and even to reach the ultra-strong coupling regime.",
        "positive": "Gate-tunable bandgap in bilayer graphene: The tight-binding model of bilayer graphene is used to find the gap between\nthe conduction and valence bands, as a function of both the gate voltage and as\nthe doping by donors or acceptors. The total Hartree energy is minimized and\nthe equation for the gap is obtained. This equation for the ratio of the gap to\nthe chemical potential is determined only by the screening constant. Thus the\ngap is strictly proportional to the gate voltage or the carrier concentration\nin the absence of donors or acceptors. In the opposite case, where the donors\nor acceptors are present, the gap demonstrates the asymmetrical behavior on the\nelectron and hole sides of the gate bias. A comparison with experimental data\nobtained by Kuzmenko et al demonstrates the good agreement."
    },
    {
        "anchor": "Multi-terminal Electron Transport Through Single Phenalenyl Molecule: A\n  Theoretical Study: We do parametric calculations to elucidate multi-terminal electron transport\nproperties through a molecular system where a single phenalenyl molecule is\nattached to semi-infinite one-dimensional metallic leads. A formalism based on\nthe Green's function technique is used for the calculations while the model is\ndescribed by tight-binding Hamiltonian. We explore the transport properties in\nterms of conductance, reflection probability as well as current-voltage\ncharacteristic. The most significant feature we articulate is that all these\ncharacteristics are very sensitive to the locations where the leads are\nconnected and also the molecule-to-lead coupling strengths. The presence of\nother leads also has a remarkable effect on these transport properties. We\nstudy these phenomena for two-, three- and four-terminal molecular systems. Our\nnumerical study may be utilized in designing tailor-made molecular electronic\ndevices.",
        "positive": "Moir\u00e9 phonons and impact of electronic symmetry breaking in twisted\n  trilayer graphene: Twisted trilayer graphene is a particularly promising moir\\'e superlattice\nsystem, due to its tunability, strong superconductivity, and complex electronic\nsymmetry breaking. Motivated by these properties, we study lattice relaxation\nand the long-wavelength phonon modes of this system. We show that\nmirror-symmetric trilayer graphene hosts, aside from the conventional acoustic\nphonon modes, two classes of shear modes, which are even and odd under mirror\nreflection. The mirror-even modes are found to be gapless and equivalent to the\n\"phason\" modes of twisted bilayer graphene, with appropriately rescaled\nparameters. The modes odd under mirror symmetry have no analogue in twisted\nbilayer graphene and exhibit a finite gap, which we show is directly\nproportional to the degree of lattice relaxation. We also discuss the impact of\nmirror-symmetry breaking, which can be tuned by a displacement field or result\nfrom a stacking shift, and of rotational- as well as time-reversal-symmetry\nbreaking, resulting from spontaneous electronic order. We demonstrate that this\ncan induce finite angular momentum to the phonon branches. Our findings are\nimportant to the interpretation of recent experiments, concerning the origin of\nsuperconductivity and of linear-in-$T$ resistivity."
    },
    {
        "anchor": "Observation of non-local impedance response in a passive electrical\n  circuit: In media with only short-ranged couplings and interactions, it is natural to\nassume that physical responses must be local. Yet, we discover that this is not\nnecessarily true, even in a system as commonplace as an electric circuit array.\nThis work reports the experimental observation of non-local impedance response\nin a designed circuit network consisting exclusively of passive elements such\nas resistors, inductors and capacitors (RLC). Measurements reveal that the\nremoval of boundary connections dramatically affects the two-point impedance\nbetween certain distant nodes, even in the absence of any amplification\nmechanism for the voltage signal. This non local impedance response is distinct\nfrom the reciprocal non-Hermitian skin effect, affecting only selected pairs of\nnodes even as the circuit Laplacian exhibits universally broken spectral\nbulk-boundary correspondence. Surprisingly, not only are component parasitic\nresistances unable to erode the non-local response, but they in fact give rise\nto novel loss-induced topological modes at sufficiently large system sizes,\nconstituting a new manifestation of the critical non-Hermitian skin effect. Our\nfindings chart a new route towards attaining non-local responses in photonic or\nelectrical metamaterials without involving non-linear, non-local, active or\namplificative elements.",
        "positive": "Interlayer donor-acceptor pair excitons in MoSe2/WSe2 moir\u00e9\n  heterobilayer: Localized interlayer excitons (LIXs) in two-dimensional moir\\'e superlattices\nexhibit sharp and dense emission peaks, making them promising as highly tunable\nsingle-photon sources. However, the fundamental nature of these LIXs is still\nelusive. Here, we show the donor-acceptor pair (DAP) mechanism as one of the\norigins of these excitonic peaks. Numerical simulation results of the DAP model\nagree with the experimental photoluminescence spectra of LIX in the moir\\'e\nMoSe2/WSe2 heterobilayer. In particular, we find that the emission\nenergy-lifetime correlation and the nonmonotonic power dependence of the\nlifetime agree well with the DAP IX model. Our results provide insight into the\nphysical mechanism of LIX formation in moir\\'e heterostructures and pave new\ndirections for engineering interlayer exciton properties in moir\\'e\nsuperlattices."
    },
    {
        "anchor": "Theory of X-ray absorption spectroscopy: a microscopic Bloch equation\n  approach for two-dimensional solid states: We develop a self-consistent Maxwell-Bloch formalism for the interaction of\nX-rays with two-dimensional crystalline materials by incorporating the Bloch\ntheorem and Coulomb many-body interaction. This formalism is illustrated for\ngraphene, by calculating the polarization-dependent XANES, formulating\nexpressions for the radiative and Meinter-Auger recombination of core-holes,\nand the discussion of microscopic insights into the spectral oscillations of\nEXAFS beyond point scattering theory. In particular, the correct inclusion of\nlattice periodicity in our evaluation allows us to assign so far uninterpreted\nspectral features in the Fourier transformed EXAFS spectrum.",
        "positive": "Silicon intercalation into the graphene-SiC interface: In this work we use LEEM, XPEEM and XPS to study how the excess Si at the\ngraphene-vacuum interface reorders itself at high temperatures. We show that\nsilicon deposited at room temperature onto multilayer graphene films grown on\nthe SiC(000[`1]) rapidly diffuses to the graphene-SiC interface when heated to\ntemperatures above 1020. In a sequence of depositions, we have been able to\nintercalate ~ 6 ML of Si into the graphene-SiC interface."
    },
    {
        "anchor": "Microwave-induced resistance oscillations in a back-gated GaAs quantum\n  well: We performed effective mass measurements employing microwave-induced\nresistance oscillation in a tunable-density GaAs/AlGaAs quantum well. Our main\nresult is a clear observation of an effective mass increase with decreasing\ndensity, in general agreement with earlier studies which investigated the\ndensity dependence of the effective mass employing Shubnikov- de Haas\noscillations. This finding provides further evidence that microwave-induced\nresistance oscillations are sensitive to electron-electron interactions and\noffer a convenient and accurate way to obtain the effective mass.",
        "positive": "Electromagnetically controlled multiferroic thermal diode: We propose an electromagnetically tunable thermal diode based on a two phase\nmultiferroics composite. Analytical and full numerical calculations for\nprototypical heterojunction composed of Iron on Barium titanate in the\ntetragonal phase demonstrate a strong heat rectification effect that can be\ncontrolled externally by a moderate electric field. This finding is of an\nimportance for thermally based information processing and sensing and can also\nbe integrated in (spin)electronic circuits for heat management and recycling."
    },
    {
        "anchor": "Polarized light emission from individual incandescent carbon nanotubes: We fabricate nanoscale lamps which have a filament consisting of a single\nmultiwalled carbon nanotube. After determining the nanotube geometry with a\ntransmission electron microscope, we use Joule heating to bring the filament to\nincandescence, with peak temperatures in excess of 2000 K. We image the thermal\nlight in both polarizations simultaneously as a function of wavelength and\ninput electrical power. The observed degree of polarization is typically of the\norder of 75%, a magnitude predicted by a Mie model of the filament that assigns\ngraphene's optical conductance $\\pi e^2/2 h$ to each nanotube wall.",
        "positive": "Towards Arbitrary Control of Lattice Interactions in Nonequilibrium\n  Condensates: There is a growing interest in investigating new states of matter using\nout-of-equilibrium lattice spin models in two dimensions. However, a control of\npairwise interactions in such systems has been elusive as due to their\nnonequilibrium nature they maintain nontrivial particle fluxes even at the\nsteady state. Here we suggest how to overcome this problem and formulate a\nmethod for engineering reconfigurable networks of nonequilibrium condensates\nwith control of individual pairwise interactions. Representing spin by\ncondensate phase, the effective two spin interactions are created with\nnonresonant pumping, are directed with dissipative channels, and are further\ncontrolled with dissipative gates. The dissipative barriers are used to block\nunwanted interactions between condensates. Together, spatial anisotropy of\ndissipation and pump profiles allow an effective control of sign and intensity\nof the coupling strength between any two neighboring sites independent of the\nrest of the spins, which we demonstrate with a two dimensional square lattice\nof polariton condensates. Experimental realisation of such fully-controllable\nnetworks offers great potential for an efficient analog Hamiltonian optimizer\nand for reservoir computing."
    },
    {
        "anchor": "All-optical polariton transistor: While optical technology provides the best solution for the transmission of\ninformation, optical logics still calls for qualitative new concepts to be\nexplored. Exciton-polaritons are composite particles, resulting from the strong\ncoupling between excitons and photons, which have recently demonstrated\nexceptional properties like huge non-linearities, long range coherence and\nsuppression of scattering. Here we demonstrate a switching scheme for\npolaritons moving in the plane of a microcavity which satisfy all the\nrequirements for an all-optical transistor. Under resonant excitation, the\npower threshold for the nonlinear increase of the polariton density is varied\nby a weak control beam, obtaining up to 19 times amplification with switching\nenergies in the range of attojoule per square micron. Polariton propagation in\nthe plane of the microcavity is then used to control the switching of a second,\nspatially separated transistor, opening the way to the implementation of\npolariton integrated circuits.",
        "positive": "Electronic properties of WS$_2$ on epitaxial graphene on SiC(0001): This work reports an electronic and micro-structural study of an appealing\nsystem for optoelectronics: tungsten disulphide WS$_2$ on epitaxial graphene\n(EG) on SiC(0001). The WS$_2$ is grown via chemical vapor deposition (CVD) onto\nthe EG. Low-energy electron diffraction (LEED) measurements assign the\nzero-degree orientation as the preferential azimuthal alignment for WS$_2$/EG.\nThe valence-band (VB) structure emerging from this alignment is investigated by\nmeans of photoelectron spectroscopy measurements, with both high space and\nenergy resolution. We find that the spin-orbit splitting of monolayer WS$_2$ on\ngraphene is of 462 meV, larger than what is reported to date for other\nsubstrates. We determine the value of the work function for the WS$_2$/EG to be\n4.5$\\pm$0.1 eV. A large shift of the WS$_2$ VB maximum is observed as well ,\ndue to the lowering of the WS$_2$ work function caused by the donor-like\ninterfacial states of EG. Density functional theory (DFT) calculations carried\nout on a coincidence supercell confirm the experimental band structure to an\nexcellent degree. X-ray photoemission electron microscopy (XPEEM) measurements\nperformed on single WS$_2$ crystals confirm the van der Waals nature of the\ninterface coupling between the two layers. In virtue of its band alignment and\nlarge spin-orbit splitting, this system gains strong appeal for optical\nspin-injection experiments and opto-spintronic applications in general."
    },
    {
        "anchor": "Limit-Cycles and Chaos in the Current Through a Quantum Dot: We investigate non-linear magneto-transport through a single level quantum\ndot coupled to ferromagnetic leads, where the electron spin is coupled to a\nlarge, external (pseudo)spin via an anisotropic exchange interaction. We find\nregimes where the average current through the dot displays self-sustained\noscillations that reflect the limit-cycles and chaos and map the dependence of\nthis behaviour on magnetic field strength and the tunnel coupling to the\nexternal leads.",
        "positive": "Microscopic many-body theory of two-dimensional coherent spectroscopy of\n  excitons and trions in atomically thin transition metal dichalcogenides: We present a microscopic many-body theory of the recently measured\ntwo-dimensional coherent spectroscopy (2DCS) of excitons and trions in\nmonolayer MoSe$_{2}$ materials {[}K. Hao \\textit{et al.}, Nano Lett.\n\\textbf{16}, 5109 (2016){]}, where excitons and trions can be well interpreted\nas repulsive and attractive polarons, respectively, in the dilute limit of\nexciton density. We derive a simple relation for the 2DCS spectrum in terms of\na modified, mixing time-dependent polaron Green function, which is valid in the\nsingle exciton limit. Our simulated spectra are in excellent qualitative\nagreement with experiments without introducing any phenomenological parameters\nsuch as decoherence rates. In particular, quantum beats between the\noff-diagonal crosspeaks in the experimental 2DCS spectra are well reproduced.\nOur work, therefore, clarifies the microscopic principle that underlies the\nobserved optical signals of exciton-trion coherence. We find that there are two\nquantitative discrepancies between theory and experiment: the smaller than\nexpected crosspeak strength and the slightly unsynchronized quantum beats at\ndifferent crosspeaks. Tentatively, we attribute these residual discrepancies to\nthe finite exciton density and the resultant polaron-polaron interaction, which\nis not taken into account in our theory."
    },
    {
        "anchor": "Spin Coated Plasmonic Nanoparticle Interfaces for Photocurrent\n  Enhancement in Thin Film Si Solar Cells: Nanoparticle (NP) arrays of noble metals strongly absorb light in the visible\nto infrared wavelengths through resonant interactions between the incident\nelectromagnetic field and the metal's free electron plasma. Such plasmonic\ninterfaces enhance light absorption and photocurrent in solar cells. We report\na cost effective and scalable room temperature/pressure spin-coating route to\nfabricate broadband plasmonic interfaces consisting of silver NPs. The NP\ninterface yields photocurrent enhancement (PE) in thin film silicon devices by\nup to 200% which is significantly greater than previously reported values. For\ncoatings produced from Ag nanoink containing particles with average diameter of\n40 nm, an optimal NP surface coverage of 7% was observed. Scanning electron\nmicroscopy of interface morphologies revealed that for low surface coverage,\nparticles are well-separated, resulting in broadband PE. At higher surface\ncoverage, formation of particle strings and clusters caused red-shifting of the\nPE peak and a narrower spectral response.",
        "positive": "Switchable valley filter based on a graphene $p$-$n$ junction in a\n  magnetic field: Low-energy excitations in graphene exhibit relativistic properties due to the\nlinear dispersion relation close to the Dirac points in the first Brillouin\nzone. Two of the Dirac points located at opposite corners of the first\nBrillouin zone can be chosen as inequivalent, representing a new valley degree\nof freedom, in addition to the charge and spin of an electron. Using the valley\ndegree of freedom to encode information has attracted significant interest,\nboth theoretically and experimentally, and gave rise to the field of\nvalleytronics. We study a graphene $p$-$n$ junction in a uniform out-of-plane\nmagnetic field as a platform to generate and controllably manipulate the valley\npolarization of electrons. We show that by tuning the external potential giving\nrise to the $p$-$n$ junction we can switch the current from one valley\npolarization to the other. We also consider the effect of different types of\nedge terminations and present a setup, where we can partition an incoming\nvalley-unpolarized current into two branches of valley-polarized currents. The\nbranching ratio can be chosen by changing the location of the $p$-$n$ junction\nusing a gate."
    },
    {
        "anchor": "Direct visualization of Rashba-split bands and spin/orbital-charge\n  interconversion at KTaO$_3$ interfaces: Rashba interfaces have emerged as promising platforms for spin-charge\ninterconversion through the direct and inverse Edelstein effects. Notably,\noxide-based two-dimensional electron gases (2DEGs) display a large and\ngate-tunable conversion efficiency, as determined by transport measurements.\nHowever, a direct visualization of the Rashba-split bands in oxide 2DEGs is\nlacking, which hampers an advanced understanding of their rich spin-orbit\nphysics. Here, we investigate KTaO$_3$-2DEGs and evidence their Rashba-split\nbands using angle resolved photoemission spectroscopy. Fitting the bands with a\ntight-binding Hamiltonian, we extract the effective Rashba coefficient and\nbring insight into the complex multiorbital nature of the band structure. Our\ncalculations reveal unconventional spin and orbital textures, showing\ncompensation effects from quasi-degenerate band pairs which strongly depend on\nin-plane anisotropy. We compute the band-resolved spin and orbital Edelstein\neffects, and predict interconversion efficiencies exceeding those of other\noxide 2DEGs. Finally, we suggest design rules for Rashba systems to optimize\nspin-charge interconversion performance.",
        "positive": "Highly Anisotropic Excitons and Multiple Phonon Bound States in a Van\n  der Waals Antiferromagnetic Insulator: Two-dimensional semiconducting systems, such as quantum wells and transition\nmetal dichalcogenides, are the foundations to investigate low dimensional\nlight-matter interactions. To date, the study of elementary photoexcitation,\nnamely the exciton, in 2D semiconductors with intrinsic magnetic order remains\na challenge due to the lack of suitable material platforms. Here, we report an\nobservation of excitons coupled to zigzag antiferromagnetic order in the\nlayered antiferromagnetic insulator NiPS3 using both photoluminescence (PL) and\noptical reflection spectroscopy. The exciton exhibits a linewidth as narrow as\n~350 ueV with near unity linear polarization in the PL spectrum. As the\nthicknesses of samples is reduced from five layers to bilayers, the PL\nintensity is drastically suppressed and eventually vanishes in monolayers,\nconsistent with the calculated bandgap being highly indirect for both bilayer\nand monolayer. We observed strong linear dichroism (LD) over a broad spectra\nrange, which shares the same optical anisotropy axis, being locked to the\nzigzag direction, as the exciton PL. Both LD and the degree of linear\npolarization in the exciton PL decrease as the temperature increases and become\nnegligible above the Neel temperature. These observations suggest both optical\nquantities are probes of the symmetry breaking magnetic order parameter. In\naddition, a sharp resonance in the LD spectrum is observed with an energy near\nthe exciton PL. There exist over ten exciton-A1g phonon bound states on its\nhigh energy side, which likely result from the strong modulation of the\nligand-to-metal charge transfer energy by strong electron-lattice interactions.\nOur work establishes NiPS3 as a new 2D platform for exploring magneto-exciton\nphysics with strong correlations, as well as a building block for 2D\nheterostructures for engineering physical phenomena with time reversal symmetry\nbreaking."
    },
    {
        "anchor": "Shot noise of a multiwalled carbon nanotube field effect transistor: We have investigated shot noise in a 6-nm-diameter, semiconducting\nmultiwalled carbon nanotube FET at 4.2 K over the frequency range 600 - 950\nMHz. We find a transconductance of 3 - 3.5 $\\mu$S for optimal positive and\nnegative source-drain voltages V. For the gate referred input voltage noise, we\nobtain 0.2 and 0.3 $\\mu{V}/ \\sqrt{Hz}$ for V>0 and V<0, respectively. As\neffective charge noise this corresponds to $2-3 \\cdot 10^{-5}$ e/$\\sqrt{Hz}$.",
        "positive": "Coherent all-optical control of a solid-state spin via a double\n  $\u039b$-system: All-optical control enables fast quantum operations on color center spins\nthat are typically realized via a single Raman transition in a\n$\\Lambda$-system. Here, we simultaneously drive both Raman transitions in a\ndouble $\\Lambda$-system to control the spin of a germanium vacancy (GeV) in\ndiamond. In doing so, we achieve fast operations, observe the quantum\ninterference between the two Raman transitions and probe the GeV coherence\n($T_2^*=224\\pm14$ ns, $T_2^{\\rm H}=11.9\\pm0.3$ $\\mu$s). Importantly, control\nvia a double $\\Lambda$-system is applicable to other color centers and\nparticularly, the group-IV defects in diamond."
    },
    {
        "anchor": "Graphene Terahertz Plasmon Oscillators: In this paper we propose and discuss coherent terahertz sources based on\ncharge density wave (plasmon) amplification in two dimensional graphene. The\ncoupling of the plasmons to interband electron-hole transitions in population\ninverted graphene layers can lead to plasmon amplification through stimulated\nemission. Plasmon gain values in graphene can be very large due to the small\ngroup velocity of the plasmons and the strong confinement of the plasmon field\nin the vicinity of the graphene layer. We present a transmission line model for\nplasmon propagation in graphene that includes plasmon dissipation and plasmon\ninterband gain due to stimulated emission. Using this model, we discuss design\nfor terahertz plasmon oscillators and derive the threshold condition for\noscillation taking into account internal losses and also losses due to external\ncoupling. The large gain values available at terahertz frequencies in graphene\ncan lead to integrated oscillators that have dimensions in the 1-10 micron\nrange.",
        "positive": "Multifarious skyrmion phases on a trilayer triangular lattice: The instability toward a magnetic skyrmion crystal in centrosymmetric\ntrilayer magnets is investigated based on a spin model with layer-dependent\nDzayloshinskii-Moriya interaction. We find various types of skyrmion crystal\nphases with different skyrmion numbers in a low-temperature phase diagram by\nperforming the simulated annealing. In addition to the N\\'eel skyrmion crystal\nphase that is expected to emerge in the presence of the polar-type\nDzayloshinskii-Moriya interaction, we obtain the skyrmion crystal phases\ncharacteristics of the layered system: the twisted surface skyrmion crystal,\nanti-skyrmion crystal, and high-topological-number skyrmion crystal phases. The\nrich magnetic phases are brought about by the synergy among the layer-dependent\nDzayloshinskii-Moriya interaction, interlayer exchange interaction, and an\nexternal magnetic field. Our results indicate that the layer degree of freedom\nat the surface and heterostructures provides a good platform to engineer and\ndesign the topological spin textures."
    },
    {
        "anchor": "Ballistic transport exceeding 28 \u03bcm in CVD grown graphene: We report on ballistic transport over more than 28 \\mu m in graphene grown by\nchemical vapor deposition (CVD) that is fully encapsulated in hexagonal boron\nnitride. The structures are fabricated by an advanced dry van-der-Waals\ntransfer method and exhibit carrier mobilities of up to three million\ncm$^2$/(Vs). The ballistic nature of charge transport is probed by measuring\nthe bend resistance in cross- and square-shaped devices. Temperature dependent\nmeasurements furthermore prove that ballistic transport is maintained exceeding\n1 \\mu m up to 200 K.",
        "positive": "Electric-field-driven conductance switching in encapsulated graphene\n  nanogaps: Feedback-controlled electric breakdown of graphene in air or vacuum is a\nwell-established way of fabricating tunnel junctions, nanogaps, and quantum\ndots. We show that the method is equally applicable to encapsulated graphene\nconstrictions fabricated using hydrogen silsesquioxane. The silica-like layer\nleft by hydrogen silsesquioxane resist after electron-beam exposure remains\nintact after electric breakdown of the graphene. We explore the conductance\nswitching behavior that is common in graphene nanostructures fabricated via\nfeedback-controlled breakdown, and show that it can be attributed to\natomic-scale fluctuations of graphene below the encapsulating layer. Our\nfindings open up new ways of fabricating encapsulated room-temperature\nsingle-electron nanodevices and shed light on the underlying physical mechanism\nof conductance switching in these graphene nanodevices."
    },
    {
        "anchor": "Positional dependence of energy gap on line defect in armchair graphene\n  nanoribbons: Two-terminal transport and related issues: The characteristics of energy band spectrum of armchair graphene nanoribbons\nin presence of line defect are analyzed within a simple non-interacting\ntight-binding framework. In metallic nanoribbons an energy gap may or may not\nappear in the band spectrum depending on the location of the defect line, while\nin semiconducting ribbons the gaps are customized, yielding the potential\napplicabilities of graphene nanoribbons in nanoscale electronic devices. With a\nmore general model, we also investigate two-terminal electron transport using\nGreen's function formalism.",
        "positive": "Nanodot to Nanowire: A strain-driven shape transition in self-organized\n  endotaxial CoSi2 on Si (100): We report a phenomenon of strain-driven shape transition in the growth of\nnanoscale self-organized endotaxial CoSi2 islands on Si (100) substrates. Small\nsquare shaped islands as small as 15\\times15 nm2 have been observed. Islands\ngrow in the square shape following the four fold symmetry of the Si (100)\nsubstrate, up to a critical size of 67 \\times 67 nm2. A shape transition takes\nplace at this critical size. Larger islands adopt a rectangular shape with ever\nincreasing length and the width decreasing to an asymptotic value of ~25 nm.\nThis produces long wires of nearly constant width.We have observed nanowire\nislands with aspect ratios as large as ~ 20:1. The long nanowire\nheterostructures grow partly above (~ 3 nm) the surface, but mostly into (~17\nnm) the Si substrate. These self-organized nanostructures behave as nanoscale\nSchottky diodes. They may be useful in Si-nanofabrication and find potential\napplication in constructing nano devices."
    },
    {
        "anchor": "Attractive and repulsive fluctuation-induced pressure in peptide films\n  deposited on semiconductor substrates: We consider the fluctuation-induced (Casimir) pressure in peptide films\ndeposited on GaAs, Ge, and ZnS substrates which are either in dielectric or\nmetallic state. Calculations of the Casimir pressure are performed in the\nframework of fundamental Lifshitz theory employing the frequency-dependent\ndielectric permittivities of all involved materials. The electric conductivity\nof semiconductor substrates is taken into account within the experimentally and\nthermodynamically consistent approach. According to our results, the Casimir\npressure in peptide films deposited on dielectric-type semiconductor substrates\nvanishes for some definite film thickness, is repulsive for thinner and\nattractive for thicker films. The dependence of this effect on the fraction of\nwater in the film and on the static dielectric permittivity of semiconductor\nsubstrate is determined. For the metallic-type semiconductor substrates, the\nCasimir pressure in peptide coatings is shown to be always repulsive. Possible\napplications of these results to the problem of stability of thin coatings in\nmicrodevices are discussed.",
        "positive": "Experimental observation and spin texture of Dirac node arcs in\n  tetradymite topological metals: We report the observation of a non-trivial spin texture in Dirac node arcs,\nnovel topological objects formed when Dirac cones of massless particles extend\nalong an open one-dimensional line in momentum space. We find that such states\nare present in all the compounds of the tetradymite M$_2$Te$_2$X family\n(M$=$Ti, Zr or Hf and X$=$P or As), regardless of the weak or strong character\nof the topological invariant. The Dirac node arcs in tetradymites are thus the\nsimplest possible, textbook example, of a type-I Dirac system with a single\nspin-polarized node arc."
    },
    {
        "anchor": "Decoherence of a qubit due to a quantum fluctuator or to a classical\n  telegraph noise: We investigate the decoherence of a qubit coupled to either a quantum\ntwo-level system (TLS) again coupled to an environment, or a classical\nfluctuator modeled by random telegraph noise. In order to do this we construct\na model for the quantum TLS where we can adjust the temperature of its\nenvironment, and the decoherence rate independently. The model has a\nwell-defined classical limit at any temperature and this corresponds to the\nappropriate random telegraph process, which is symmetric at high temperatures\nand becomes asymmetric at low temperatures. We find that the difference in the\nqubit decoherence rates predicted by the two models depends on the ratio\nbetween the qubit-TLS coupling and the decoherence rate in the pointer basis of\nthe TLS. This is then the relevant parameter which determines whether the TLS\nhas to be treated quantum mechanically or can be replaced by a classical\ntelegraph process. We also compare the mutual information between the qubit and\nthe TLS in the classical and quantum cases.",
        "positive": "All-optical tuning of a quantum dot in a coupled cavity system: We demonstrate a method of tuning a semiconductor quantum dot (QD) onto\nresonance with a cavity mode all-optically. We use a system comprised of two\nevanescently coupled cavities containing a single QD. One resonance of the\ncoupled cavity system is used to generate a cavity enhanced optical Stark\nshift, enabling the QD to be resonantly tuned to the other cavity mode. A\ntwenty-seven fold increase in photon emission from the QD is measured when the\noff-resonant QD is Stark shifted into the cavity mode resonance, which is\nattributed to radiative enhancement of the QD. A maximum tuning of 0.06 nm is\nachieved for the QD at an incident power of 88 {\\mu}W."
    },
    {
        "anchor": "Quantum model for mode locking in pulsed semiconductor quantum dots: Quantum dots in GaAs/InGaAs structures have been proposed as a candidate\nsystem for realizing quantum computing. The short coherence time of the\nelectronic quantum state that arises from coupling to the nuclei of the\nsubstrate is dramatically increased if the system is subjected to a magnetic\nfield and to repeated optical pulsing. This enhancement is due to mode locking:\nOscillation frequencies resonant with the pulsing frequencies are enhanced,\nwhile off-resonant oscillations eventually die out. Because the resonant\nfrequencies are determined by the pulsing frequency only, the system becomes\nimmune to frequency shifts caused by the nuclear coupling and by slight\nvariations between individual quantum dots. The effects remain even after the\noptical pulsing is terminated. In this work, we explore the phenomenon of mode\nlocking from a quantum mechanical perspective. We treat the dynamics using the\ncentral spin model, which includes coupling to 10-20 nuclei and incoherent\ndecay of the excited electronic state, in a perturbative framework. Using\nscaling arguments, we extrapolate our results to realistic system parameters.\nWe find that the synchronization to the pulsing frequency needs time scales in\nthe order of 1 s.",
        "positive": "Sub-threshold channels at the edges of nanoscale triple-gate silicon\n  transistors: We investigate by low-temperature transport experiments the sub-threshold\nbehavior of triple-gate silicon field-effect transistors. These\nthree-dimensional nano-scale devices consist of a lithographically defined\nsilicon nanowire surrounded by a gate with an active region as small as a few\ntens of nanometers, down to 50x60x35 nm^3. Conductance versus gate voltage show\nCoulomb-blockade oscillations with a large charging energy due to the formation\nof a small potential well below the gate. According to dependencies on device\ngeometry and thermionic current analysis, we conclude that sub-threshold\nchannels, a few nanometers wide, appear at the nanowire edges, hence providing\nan experimental evidence for the corner-effect."
    },
    {
        "anchor": "Dirac magnons pairing via pumping: We study pumping of magnons to the Dirac points of magnon's Brillouin zone of\na ferromagnet on a honeycomb lattice. In particular, we consider second-order\nSuhl process, when due to interaction between magnons, a pair of magnons is\ncreated due to absorption of two electromagnetic wave quanta. We introduce a\nbosonic analog of the Cooper ladder for the magnon pair, which is shown to\nenhance the pairing of magnons at the Dirac points. As a result of pairing of\nthe Dirac magnons, the system becomes unstable towards formation of a magnetic\nstate with zero or reduced magnetization - the Dirac magnon paired state. In\nthis case the resonant frequency of the pump equals to that of energy of the\nDirac points. Our estimates suggest that the Dirac magnon paired state can be\nfound in the CrBr$_{3}$ or CrCl$_{3}$ ferromagnet below in vicinity of the\nCurie temperature.",
        "positive": "Nonlinear optical Hall effect in Weyl semimetal WTe2: The ordinary Hall effect refers to generation of a transverse voltage upon\nexertion of an electric field in the presence of an out-of-plane magnetic\nfield. While a linear Hall effect is commonly observed in systems with breaking\ntime-reversal symmetry via an applied external magnetic field or their\nintrinsic magnetization1, 2, a nonlinear Hall effect can generically occur in\nnon-magnetic systems associated with a nonvanishing Berry curvature dipole3.\nHere we report, observations of a nonlinear optical Hall effect in a Weyl\nsemimetal WTe2 without an applied magnetic field at room temperature. We\nobserve an optical Hall effect resulting in a polarization rotation of the\nreflected light, referred to as the nonlinear Kerr rotation. The nonlinear Kerr\nrotation linearly depends on the charge current and optical power, which\nmanifests the fourth-order nonlinearity. We quantitatively determine the\nfourth-order susceptibility, which exhibits strong anisotropy depending on the\ndirections of the charge current and the light polarization. Employing symmetry\nanalysis of Berry curvature multipoles, we demonstrate that the nonlinear Kerr\nrotations can arise from the Berry curvature hexapole allowed by the\ncrystalline symmetries of WTe2. There also exist marginal signals that are\nincompatible with the symmetries, which suggest a hidden phase associated with\nthe nonlinear process."
    },
    {
        "anchor": "Observation of a Nanoscale Metallic Dot Self-Consistently Coupled to a\n  Two-Level System: We have observed anomalous transport properties for a 50 nm Bi dot in the\nCoulomb-blockade regime. Over a range of gate voltages, Coulomb blockade peaks\nare suppressed at low bias, and dramatic structure appears in the current at\nhigher bias. We propose that the state of the dot is determined\nself-consistently with the state of a nearby two-level system (TLS) to which it\nis electrostatically coupled. As a gate voltage is swept, the ground state\nalternates between states of the TLS, leading to skipped Coulomb-blockade peaks\nat low bias. At a fixed gate voltage and high bias, transport may occur through\na cascade of excited states connected by the dynamic switching of the TLS.",
        "positive": "Luminescence anomaly of dipolar valley excitons in homobilayer\n  semiconductor moir\u00e9 superlattices: In twisted homobilayer transition metal dichalcogenides, intra- and\ninter-layer valley excitons hybridize with the layer configurations spatially\nvarying in the moir\\'e. The ground state valley excitons are trapped at two\nhigh-symmetry points with opposite electric dipoles in a moir\\'e supercell,\nforming a honeycomb superlattice of nearest-neighbor dipolar attraction. We\nfind that the spatial texture of layer configuration results in a luminescence\nanomaly of the moir\\'e trapped excitons, where a tiny displacement by\ninteractions dramatically increases the brightness and changes polarization\nfrom circular to linear. At full filling, radiative recombination predominantly\noccurs at edges and vacancies of the exciton superlattice. The anomaly also\nmanifests in the cascaded emission of small clusters, producing chains of\npolarization entangled photons. An interlayer bias can switch the superlattice\ninto a single-orbital triangular lattice with repulsive interactions only,\nwhere the luminescence anomaly can be exploited to distinguish ordered states\nand domain boundaries at fractional filling."
    },
    {
        "anchor": "Transparent Josephson Junctions in Higher-Order Topological Insulator\n  WTe2 via Pd Diffusion: Highly transparent superconducting contacts to a topological insulator (TI)\nremain a persistent challenge on the route to engineer topological\nsuperconductivity. Recently, the higher-order TI WTe$_2$ was shown to turn\nsuperconducting when placed on palladium (Pd) bottom contacts, demonstrating a\npromising material system in pursuing this goal. Here, we report the diffusion\nof Pd into WTe$_2$ and the formation of superconducting PdTe$_x$ as the origin\nof observed superconductivity. We find an atomically sharp interface in\nvertical direction to the van der Waals layers between the diffusion crystal\nand its host crystal, forming state-of-the-art superconducting contacts to a\nTI. The diffusion is discovered to be non-uniform along the width of the\nWTe$_2$ crystal, with a greater extend along the edges compared to the bulk.\nThe potential of this contacting method is highlighted in transport\nmeasurements on Josephson junctions by employing external superconducting\nleads.",
        "positive": "Signature of interaction in dc transport of ac gated Quantum Spin Hall\n  edge states: In the presence of a scattering potential, electron transport in a quantum\nwire is known to be dramatically modified by backward scattering and unaffected\nby forward scattering processes. We show that the scenario is quite different\nin Quantum Spin Hall effect edge states coupled at a constriction. The helical\nnature of these states leads to the appearance of a forward scattering spin\nchannel that is absent in other Luttinger liquid realizations. Suitably applied\nac gate voltages can thus operate on the spin of electrons tunneling across the\nconstriction, and induce in the dc tunneling current a cusp pattern that\nrepresents the signature of the edge state electronic interaction."
    },
    {
        "anchor": "Efficiency of three-terminal thermoelectric transport under broken-time\n  reversal symmetry: We investigate thermoelectric efficiency of systems with broken time reversal\nsymmetry under a three-terminal transport. Using a model of Aharonov-Bohm\ninterferometer formed with three noninteracting quantum dots, we show that\nCarnot efficiency can be achieved when the thermopower is a symmetric function\nof the applied magnetic field. On the other hand, the maximal value of the\nefficiency at maximum power is obtained for asymmetric thermopower. Indeed, we\nshow that Curzon-Ahlborn limit is exceeded within the linear response regime in\nour model. Moreover, we investigate thermoelectric efficiency for random\nHamiltonians drawn from the Gaussian Unitary Ensemble and for a more abstract\ntransmission model. In this latter model we find that the efficiency is\nimproved using sharp energy-dependent transmission functions.",
        "positive": "Understanding of hopping matrix for 2D materials taking 2D honeycomb and\n  square lattices as study cases: In this work, a trial understanding for the physics underling the\nconstruction of exchange (hopping) matrix $\\mathbf{E}$ in Heisenberg model\n(tight binding model) for 2D materials is done. It is found that the\n$\\mathbf{E}$ matrix describes the particles exchange flow under short range\n(nearest neighbor) hopping interaction which is effected by the lattice\ngeometry. This understanding is then used to explain the dispersion relations\nfor the 2D honeycomb lattice with zigzag and armchair edges obtained for\ngraphene nanoribbons and magnetic stripes. It is found that the particle flow\nby hopping in the zigzag nanoribbons is a translation flow and shows\n$\\mathbf{\\cos^2}(q_xa)$ dependance while it is a rotational flow in the\narmchair nanoribbons. At $q_xa/\\pi=0.5$, the particles flow in the edge sites\nof zigzag nanoribbons with dependance of $\\mathbf{\\cos^2}(q_xa)$ is equal to\nzero. At the same time there is no vertical hopping in those edge sites which\nlead to the appearance of peculiar zigzag flat localized edge states."
    },
    {
        "anchor": "Topological interface states mediated by spontaneous symmetry breaking: We propose a one-dimensional nonlinear system of coupled anharmonic\noscillators that dynamically undergoes a topological transition switching from\nthe {disordered} and topologically trivial phase into the nontrivial one due to\nthe spontaneous symmetry breaking. The topological transition is accompanied by\nthe formation of the topological interface state in the spectrum of linearized\nexcitations of the stationary phase. Our findings thus highlight the potential\nof the nonlinear systems for hosting the topological phases and uncover a\nfundamental link between the spontaneous symmetry breaking mechanism and\ntopological edge states.",
        "positive": "Perturbation theory of the dynamic inverse spin Hall effect with charge\n  conservation: We present gauge-invariant theory of the dynamic inverse spin Hall effect\ndriven by the spin--orbit interaction in metallic systems. Charge conservation\nis imposed diagrammatically by including vertex corrections. We show the charge\ncurrent is induced by an effective electric field that is proportional to the\nspin current pumped by the magnetization dynamics. The result is consistent\nwith recent experiments."
    },
    {
        "anchor": "Quasibound states at thresholds in multichannel impurity scattering: We investigate the threshold behavior of transmission resonances and\nquasibound states in the multichannel scattering problems of a one dimensional\n(1D) time-dependent impurity potential, and the related problem of a single\nimpurity in a quasi 1D wire. It was claimed before in the literature that a\nquasibound state disappears when a transmission zero collides with the subband\nboundary. However, the transmission line shape, the Friedel sum rule, and the\ndelay time show that the quasibound states still survive and affect the\nphysical quantities. We discuss the relation between threshold behavior of\ntransmission resonances, and quasibound states and their boundary conditions in\nthe general context of multichannel scatterings.",
        "positive": "Spin-valley interplay in two-dimensional disordered electron liquid: We report the detailed study of the influence of the spin and valley\nsplittings on such physical observables of the two-dimensional disordered\nelectron liquid as resistivity, spin and valley susceptibilities. We explain\nqualitatively the nonmonotonic dependence of the resistivity with temperature\nin the presence of a parallel magnetic field. In the presence of either the\nspin splitting or the valley splitting we predict novel, with two maximum\npoints, temperature dependence of the resistivity."
    },
    {
        "anchor": "Hexagonal Boron Nitride Phononic Crystal Waveguides: Hexagonal boron nitride (h-BN), one of the hallmark van der Waals (vdW)\nlayered crystals with an ensemble of attractive physical properties, is playing\nincreasingly important roles in exploring two-dimensional (2D) electronics,\nphotonics, mechanics, and emerging quantum engineering. Here, we report on the\ndemonstration of h-BN phononic crystal waveguides with designed pass and stop\nbands in the radio frequency (RF) range and controllable wave propagation and\ntransmission, by harnessing arrays of coupled h-BN nanomechanical resonators\nwith engineerable coupling strength. Experimental measurements validate that\nthese phononic crystal waveguides confine and support 15 to 24 megahertz (MHz)\nwave propagation over 1.2 millimeters. Analogous to solid-state atomic crystal\nlattices, phononic bandgaps and dispersive behaviors have been observed and\nsystematically investigated in the h-BN phononic waveguides. Guiding and\nmanipulating acoustic waves on such additively integratable h-BN platform may\nfacilitate multiphysical coupling and information transduction, and open up new\nopportunities for coherent on-chip signal processing and communication via\nemerging h-BN photonic and phononic devices.",
        "positive": "Observation of Acoustic Non-Hermitian Bloch Braids and Associated\n  Topological Phase Transitions: Topological features embedded in ancient braiding and knotting arts endow\nsignificant impacts on our daily life and even cutting-edge science. Recently,\nfast growing efforts are invested to the braiding topology of complex Bloch\nbands in non-Hermitian systems. This new classification of band topology goes\nfar beyond those established in Hermitian counterparts. Here, we present the\nfirst acoustic realization of the topological non-Hermitian Bloch braids, based\non a two-band model easily accessible for realizing any desired knot structure.\nThe non-Hermitian bands are synthesized by a simple binary cavity-tube system,\nwhere the long-range, complex-valued, and momentum-resolved couplings are\naccomplished by a well-controlled unidirectional coupler. In addition to\ndirectly visualizing various two-band braiding patterns, we unambiguously\nobserve the highly-elusive topological phase transitions between them. Not only\ndo our results provide a direct demonstration for the non-Hermitian band\ntopology, but also the experimental techniques open new avenues for designing\nunconventional acoustic metamaterials."
    },
    {
        "anchor": "Unidirectional spin-wave channeling along magnetic domain walls of Bloch\n  type: From the pioneering work of Winter [Phys. Rev. 124, 452 (1961)], a magnetic\ndomain wall of Bloch type is known to host a special wall-bound spin-wave mode,\nwhich corresponds to spin-waves being channeled along the magnetic texture.\nUsing micromagnetic simulations, we investigate spin-waves travelling inside\nBloch walls formed in thin magnetic media with perpendicular-to-plane magnetic\nanisotropy and we show that their propagation is actually strongly\nnonreciprocal, as a result of dynamic dipolar interactions. We investigate\nspin-wave non-reciprocity effects in single Bloch walls, which allows us to\nclearly pinpoint their origin, as well as in arrays of parallel walls in stripe\ndomain configurations. For such arrays, a complex domain-wall-bound spin-wave\nband structure develops, some aspects of which can be understood qualitatively\nfrom the single-wall picture by considering that a wall array consists of a\nsequence of up/down and down/up walls with opposite non-reciprocities.\nCircumstances are identified in which the non-reciprocity is so extreme that\nspin-wave propagation inside individual walls becomes unidirectional.",
        "positive": "Distinct Competing Ordered \u03bd=2 States in Bilayer Graphene: Because of its large density-of-states and the 2{\\pi} Berry phase near its\nlow-energy band-contact points, neutral bilayer graphene (BLG) at zero magnetic\nfield (B) is susceptible to chiral-symmetry breaking, leading to a variety of\ngapped spontaneous quantum Hall states distinguished by valley and\nspin-dependent quantized Hall conductivities. Among these, the layer\nantiferromagnetic state, which has quantum valley Hall (QVH) effects of\nopposite sign for opposite spins, appears to be the thermodynamic ground state.\nThough other gapped states have not been observed experimentally at B=0, they\ncan be explored by exploiting their adiabatic connection to quantum Hall states\nwith the same total Hall conductivity {\\sigma}H. In this paper, by using a\nmagnetic field to select filling factor {\\nu}=2 states with {\\sigma}H=2e^2/h,\nwe demonstrate the presence of a quantum anomalous Hall (QAH) state for the\nmajority spin, and a Kekul\\'e state with spontaneous valley coherence and a\nquantum valley Hall state for the minority spin in BLG. By providing the first\nspectroscopic mapping of spontaneous Hall states at {\\nu}=2, our results shed\nfurther light on the rich set of competing ordered states in BLG."
    },
    {
        "anchor": "Direct Observation of Cross-Polarized Excitons in Aligned\n  Single-Chirality Single-Wall Carbon Nanotubes: Optical properties of single-wall carbon nanotubes (SWCNTs) for light\npolarized parallel to the nanotube axis have been extensively studied, whereas\ntheir response to light polarized perpendicular to the nanotube axis has not\nbeen well explored. Here, by using a macroscopic film of highly aligned\nsingle-chirality (6,5) SWCNTs, we performed a systematic polarization-dependent\noptical absorption spectroscopy study. In addition to the commonly observed\nangular-momentum-conserving interband absorption of parallel-polarized light,\nwhich generates $E_{11}$ and $E_{22}$ excitons, we observed a small but\nunambiguous absorption peak whose intensity is maximum for\nperpendicular-polarized light. We attribute this feature to the lowest-energy\ncross-polarized interband absorption processes that change the angular momentum\nalong the nanotube axis by $\\pm 1$, generating $E_{12}$ and $E_{21}$ excitons.\nThe energy difference between the $E_{12}$ and $E_{21}$ exciton peaks, expected\nfrom asymmetry between the conduction and valence bands, was smaller than the\nobserved linewidth. Unlike previous observations of cross-polarized excitons in\npolarization-dependent photoluminescence and circular dichroism spectroscopy\nexperiments, our direct observation using absorption spectroscopy allowed us to\nquantitatively analyze this resonance. Specifically, we determined the energy\nand oscillator strength of this resonance to be 1.54 and 0.05, respectively,\ncompared with the values for the $E_{11}$ exciton peak. These values, in\ncombination with comparison with theoretical calculations, in turn led to an\nassessment of the environmental effect on the strength of Coulomb interactions\nin this aligned single-chirality SWCNT film.",
        "positive": "A Josephson phase battery: A battery is a classical apparatus which converts a chemical reaction into a\npersistent voltage bias able to power electronic circuits. Similarly, a phase\nbattery is a quantum equipment which provides a persistent phase bias to the\nwave function of a quantum circuit. It represents a key element for quantum\ntechnologies based on quantum coherence. Unlike the voltage batteries, a phase\nbattery has not been implemented so far, mainly because of the natural rigidity\nof the quantum phase that, in typical quantum circuits, is imposed by the\nparity and time-reversal symmetry constrains. Here we report on the first\nexperimental realization of a phase battery in a hybrid superconducting\ncircuit. It consists of an n-doped InAs nanowire with unpaired-spin surface\nstates and proximitized by Al superconducting leads. We find that the\nferromagnetic polarization of the unpaired-spin states is efficiently converted\ninto a persistent phase bias $\\varphi_0$ across the wire, leading to the\nanomalous Josephson effect. By applying an external in-plane magnetic field a\ncontinuous tuning of $\\varphi_0$ is achieved. This allows the charging and\ndischarging of the quantum phase battery and reveals the symmetries of the\nanomalous Josephson effect predicted by our theoretical model. Our results\ndemonstrate how the combined action of spin-orbit coupling and exchange\ninteraction breaks the phase rigidity of the system inducing a strong coupling\nbetween charge, spin and superconducting phase. This interplay opens avenues\nfor topological quantum technologies, superconducting circuitry and advanced\nschemes of circuit quantum electrodynamics.}"
    },
    {
        "anchor": "Photon pumping in a weakly-driven quantum cavity-spin system: We investigate the photon pumping effect in a topological model consisting of\na periodically driven spin-1/2 coupled to a quantum cavity mode out of the\nadiabatic limit. In the strong-drive adiabatic limit, a quantized frequency\nconversion of photons is expected as the temporal analog of the Hall current.\nWe numerically establish a novel photon pumping phenomenon in the\nexperimentally accessible nonadiabatic driving regime for a broad region of the\nparameter space. The photon frequency conversion efficiency exhibits strong\nfluctuations and high efficiency that can reach up 80% of the quantized value\nfor commensurate frequency combinations. We link the pumping properties to the\ndelocalization of the corresponding Floquet states which display multifractal\nbehavior as the result of hybridization between localized and delocalized\nsectors. Finally we demonstrate that the quantum coherence properties of the\ninitial state are preserved during the frequency conversion process in both the\nstrong and ultra-weak-drive limit.",
        "positive": "Electron transport in nanoscale junctions with local anharmonic modes: We study electron transport in nanojunctions in which an electron on a\nquantum dot or a molecule is interacting with an N-state local impurity, a\nharmonic (\"Holstein\") mode, or a two-state system (\"spin\"). These two models,\nthe Anderson-Holstein model and the spin-fermion model, can be conveniently\ntransformed by a shift transformation into a form suitable for a perturbative\nexpansion in the tunneling matrix element. We explore the current-voltage\ncharacteristics of the two models in the limit of high temperature and weak\nelectron-metal coupling using a kinetic rate equation formalism, considering\nboth the case of an equilibrated impurity, and the unequilibrated case.\nSpecifically, we show that the analog of the Franck-Condon blockade physics is\nmissing in the spin-fermion model. We complement this study by considering the\nlow-temperature quantum adiabatic limit of the dissipative spin-fermion model,\nwith fast tunneling electrons and a slow impurity. While a mean-field analysis\nof the Anderson-Holstein model suggests that nonlinear functionalities,\nbistability and hysteresis may develop, such effects are missing in the\nspin-fermion model at the mean-field level."
    },
    {
        "anchor": "One-dimensional Topological Edge States of Bismuth Bilayers: The hallmark of a time-reversal symmetry protected topologically insulating\nstate of matter in two-dimensions (2D) is the existence of chiral edge modes\npropagating along the perimeter of the system. To date, evidence for such\nelectronic modes has come from experiments on semiconducting heterostructures\nin the topological phase which showed approximately quantized values of the\noverall conductance as well as edge-dominated current flow. However, there have\nnot been any spectroscopic measurements to demonstrate the one-dimensional (1D)\nnature of the edge modes. Among the first systems predicted to be a 2D\ntopological insulator are bilayers of bismuth (Bi) and there have been recent\nexperimental indications of possible topological boundary states at their\nedges. However, the experiments on such bilayers suffered from irregular\nstructure of their edges or the coupling of the edge states to substrate's bulk\nstates. Here we report scanning tunneling microscopy (STM) experiments which\nshow that a subset of the predicted Bi-bilayers' edge states are decoupled from\nstates of Bi substrate and provide direct spectroscopic evidence of their 1D\nnature. Moreover, by visualizing the quantum interference of edge mode\nquasi-particles in confined geometries, we demonstrate their remarkable\ncoherent propagation along the edge with scattering properties that are\nconsistent with strong suppression of backscattering as predicted for the\npropagating topological edge states.",
        "positive": "Time-resolved imaging of \u0152rsted field induced magnetization dynamics\n  in cylindrical magnetic nanowires: Recent studies in three dimensional spintronics propose that the \\OE rsted\nfield plays a significant role in cylindrical nanowires. However, there is no\ndirect report of its impact on magnetic textures. Here, we use time-resolved\nscanning transmission X-ray microscopy to image the dynamic response of\nmagnetization in cylindrical Co$_{30}$Ni$_{70}$ nanowires subjected to\nnanosecond \\OE rsted field pulses. We observe the tilting of longitudinally\nmagnetized domains towards the azimuthal \\OE rsted field direction and create a\nrobust model to reproduce the differential magnetic contrasts and extract the\nangle of tilt. Further, we report the compression and expansion, or breathing,\nof a Bloch-point domain wall that occurs when weak pulses with opposite sign\nare applied. We expect that this work lays the foundation for and provides an\nincentive to further studying complex and fascinating magnetization dynamics in\nnanowires, especially the predicted ultra-fast domain wall motion and\nassociated spin wave emissions."
    },
    {
        "anchor": "Novel Exotic Magnetic Spin-order in Co5Ge3 Nano-size Materials: The Cobalt-germanium (Co-Ge) is a fascinating complex alloy system that has\nunique structure and exhibit range of interesting magnetic properties which\nwould change when reduce to nanoscale dimension. At this experimental work, the\nhigh-aspect-ratio Co5Ge3 nanoparticle with average size of 8nm was synthesized\nby gas aggregation-type cluster-deposition technology. The nanostructure\nmorphology of the as-made binary Co5Ge3 nanoparticles demonstrate excellent\nsingle-crystalline hexagonal structure with mostly preferable growth along\n(110) and (102) directions. In contrast the bulk possess Pauli paramagnetic\nspin-order at all range of temperature, here we discover size-driven new\nmagnetic ordering of as-synthesized Co5Ge3 nanoparticles exhibiting\nferromagnetism at room temperature with saturation magnetization of Ms = 32.2\nemu/cm3. This is first report of observing such new magnetic spin ordering in\nthis kind of material at nano-size which the magnetization has lower\nsensitivity to thermal energy fluctuation and exhibit high Curie temperature\nclose to 850 K. This ferromagnetic behavior along with higher Curie temperature\nat Co5Ge3 nanoparticles are attributes to low-dimension and quantum-confinement\neffect which imposes strong spin coupling and provides a new set of size-driven\nspin structures in Co5Ge3 nanoparticle which no such magnetic behavior being\npresent in the bulk of same material. This fundamental scientific study\nprovides important insights into the formation, structural, and the magnetic\nproperty of sub 10nm Co5Ge3 nanostructure which shall lead to promising\npractical versatile applications for magneto- germanide based nano-devices.",
        "positive": "Universal image segmentation for optical identification of 2D materials: Machine learning methods are changing the way data is analyzed. One of the\nmost powerful and widespread applications of these techniques is in image\nsegmentation wherein disparate objects of a digital image are partitioned and\nclassified. Here we present an image segmentation program incorporating a\nseries of unsupervised clustering algorithms for the automatic thickness\nidentification of two-dimensional materials from digital optical microscopy\nimages. The program identifies mono- and few-layer flakes of a variety of\nmaterials on both opaque and transparent substrates with a pixel accuracy of\nroughly 95%. Contrasting with previous attempts, application generality is\nachieved through preservation and analysis of all three digital color channels\nand Gaussian mixture model fits to arbitrarily shaped data clusters. Our\nresults provide a facile implementation of data clustering for the universal,\nautomatic identification of two-dimensional materials exfoliated onto any\nsubstrate."
    },
    {
        "anchor": "Long-range transport of 2D excitons with acoustic waves: Excitons are elementary optical excitation in semiconductors. The ability to\nmanipulate and transport these quasiparticles would enable excitonic circuits\nand devices for quantum photonic technologies. Recently, interlayer excitons in\n2D semiconductors have emerged as a promising candidate for engineering\nexcitonic devices due to their long lifetime, large exciton binding energy, and\ngate tunability. However, the charge-neutral nature of the excitons leads to\nweak response to the in-plane electric field and thus inhibits transport beyond\nthe diffusion length. Here, we demonstrate the directional transport of\ninterlayer excitons in bilayer WSe2 driven by the propagating potential traps\ninduced by surface acoustic waves (SAW). We show that at 100 K, the SAW-driven\nexcitonic transport is activated above a threshold acoustic power and reaches\n20 mm, a distance at least ten times longer than the diffusion length and only\nlimited by the device size. Temperature-dependent measurement reveals the\ntransition from the diffusion-limited regime at low temperature to the acoustic\nfield-driven regime at elevated temperature. Our work shows that acoustic waves\nare an effective, contact-free means to control exciton dynamics and transport,\npromising for realizing 2D materials-based excitonic devices such as exciton\ntransistors, switches, and transducers up to room temperature.",
        "positive": "Tunnelling magnetoresistance anomalies of a Coulomb blockaded quantum\n  dot: We consider quantum transport and tunneling magnetoresistance (TMR) through\nan interacting quantum dot in the Coulomb blockade regime, attached to\nferromagnetic leads. We show that there exist two kinds of anomalies of TMR,\nwhich have different origin. One type, associated with TMR sign change and\nappearing at conductance resonances, is of single particle origin. The second\ntype, inducing a pronounced increase of TMR value far beyond 100%, is caused by\nelectron correlations. It is manifested in-between Coulomb blockade conductance\npeaks. Both types of anomalies are discussed for zero and finite bias and their\nrobustness to the temperature increase is also demonstrated. The results are\npresented in the context of recent experiments on semiconductor quantum dots in\nwhich similar features of TMR have been observed."
    },
    {
        "anchor": "Duality in the Quantum Hall Effect - the Role of Electron Spin: At low temperatures the phase diagram for the quantum Hall effect has a\npowerful symmetry arising from the Law of Corresponding States. This symmetry\ngives rise to an infinite order discrete group which is a generalisation of\nKramers-Wannier duality for the two dimensional Ising model. The duality group,\nwhich is a subgroup of the modular group, is analysed and it is argued that\nthere is a quantitative difference between a situation in which the spin\nsplitting of electron energy levels is comparable to the cyclotron energy and\none in which the spin splitting is much less than the cyclotron energy. In the\nformer case the group of symmetries is larger than in the latter case. These\nduality symmetries are used to constrain the scaling functions of the theory\nand, under an assumption of complex meromorphicity, a unique functional form is\nobtained for the crossover of the conductivities between Hall states as a\nfunction of the external magnetic field. This analytic form is shown to give\ngood agreement with experimental data.\n  The analysis requires a consideration of the way in which longitudinal\nresistivities are extracted from the experimentally measured longitudinal\nresistances and a novel method is proposed for determining the correct\nnormalisation for the former.",
        "positive": "Spin-dependent diffraction at ferromagnetic/spin spiral interface: Spin-dependent transport is investigated in ballistic regime through the\ninterface between a ferromagnet and a spin spiral. We show that spin-dependent\ninterferences lead to a new type of diffraction called \"spin-diffraction\". It\nis shown that this spin-diffraction leads to local spin and electrical currents\nalong the interface. This study also shows that in highly non homogeneous\nmagnetic configuration (non adiabatic limit), the contribution of the\ndiffracted electrons is crucial to describe spin transport in such structures."
    },
    {
        "anchor": "Evolution of $nu=1$ Bilayer Quantum Hall Ferromagnet: The natures of the ground state in a $\\nu_{\\rm T}=1$ bilayer quantum Hall\nsystem at a variety of layer spacing are investigated. At small layer\nseparations the system exhibits spontaneous interlayer phase coherence. It is\nclaimed that the Halperin's (1,1,1) state is not relevant in the incompressible\nregime near the incompressible to compressible transition point in which the\nJosephson-like effect was observed. The two-particle correlation function shows\nthe deflated correlation hole at this regime. An effective model that can give\na good approximation to the ground state is proposed. A connection to the\nmodified composite fermion theory is discussed.",
        "positive": "Spin angular impulse due to spin-dependent reflection off a barrier: The spin-dependent elastic reflection of quasi two-dimensional electrons from\na lateral impenetrable barrier in the presence of band-structure spin-orbit\ncoupling results in a spin angular impulse exerted on the electrons which is\nproportional to the nontrivial difference between the electrons' momentum and\nvelocity. Even for an unpolarized incoming beam we find that the spin angular\nimpulse is nonzero when averaged over all components of the reflected beam. We\npresent a detailed analysis of the kinematics of this process."
    },
    {
        "anchor": "Spin-selective magneto-conductivity in WSe$_2$: Material systems that exhibit tunable spin-selective conductivity are key\ncomponents of spintronic technologies. Here we demonstrate a novel type of\nspin-selective transport, based on the unusual Landau level (LL) sequence\nobserved in bilayer WSe$_2$ under large applied magnetic fields. We find that\nthe conductivity depends strongly on the relative iso-spin ordering between\nconducting electrons in a partially filled LL and the localized electrons of\nlower energy filled LLs, with conductivity observed to be almost completely\nsuppressed when the spin-ratio and field-tuned Coulomb energy exceed a critical\nthreshold. Switching between \"on/off\" states is achievable through either\nmodulation of the external magnetic or electric fields, with many-body\ninteraction driving a collective switching mechanism. In contrast to\nmagnetoresistive heterostructures, this system achieves electrically tunable\nspin filtering within a single material, driven by interaction between free and\nlocalized spins residing in energy-separated spin/valley polarized bands.\nSimilar spin-selective conductivity may be realizable in multi-flat band\nsystems at zero magnetic field.",
        "positive": "Nearly flat bands in twisted triple bilayer graphene: We investigate the electronic structure of alternating-twist triple\nBernal-stacked bilayer graphene (t3BG) as a function of interlayer coupling\n$\\omega$, twist angle $\\theta$, interlayer potential difference $\\Delta$, and\ntop-bottom bilayers sliding vector $\\boldsymbol{\\tau}$ for three possible\nconfigurations AB/AB/AB, AB/BA/AB, and AB/AB/BA. The parabolic low-energy band\ndispersions in a Bernal-stacked bilayer and gap-opening through a finite\ninterlayer potential difference $\\Delta$ allows the flattening of bands in t3BG\ndown to $\\sim 20$~meV for twist angles $\\theta \\lesssim 2^{\\circ}$ regardless\nof the stacking types. The easier isolation of the flat bands and associated\nreduction of Coulomb screening thanks to the intrinsic gaps of bilayer graphene\nfor finite $\\Delta$ facilitate the formation of correlation-driven gaps when it\nis compared to the metallic phases of twisted trilayer graphene under electric\nfields. We obtain the stacking dependent Coulomb energy versus bandwidth $U/W\n\\gtrsim 1$ ratios in the $\\theta$ and $\\Delta$ parameter space. We also present\nthe expected $K$-valley Chern numbers for the lowest-energy nearly flat bands."
    },
    {
        "anchor": "Effects of spin and exchange interaction on the Coulomb-blockade peak\n  statistics in quantum dots: We derive a closed expression for the linear conductance through a quantum\ndot in the Coulomb-blockade regime in the presence of a constant exchange\ninteraction. With this expression we calculate the temperature dependence of\nthe conductance peak-height and peak-spacing statistics. Using a realistic\nvalue of the exchange interaction, we find significantly better agreement with\nexperimental data as compared with the statistics obtained in the absence of an\nexchange interaction.",
        "positive": "Theory of Nonequilibrium Coherent Transport through an Interacting\n  Mesoscopic Region Weakly Coupled to Electrodes: We develop a theory for the nonequilibrium coherent transport through a\nmesoscopic region, based on the nonequilibrium Green function technique. The\ntheory requires the weak coupling between the central mesoscopic region and the\nmultiple electrodes connected to it, but allows arbitrary hopping and\ninteraction in the central region. An equation determining the nonequilibrium\ndistribution in the central interacting region is derived and plays an\nimportant role in the theory. The theory is applied to two special cases for\ndemonstrations, revealing the novel effects associated with the combination of\nphase coherence, Coulomb interaction, and nonequilibrium distribution."
    },
    {
        "anchor": "Electron transport in interacting hybrid mesoscopic systems: A unified theory for the current through a nanoscale region of interacting\nelectrons connected to two leads which can be either ferromagnet or\nsuperconductor is presented, yielding Meir-Wingreen-type formulas when applied\nto specific circumstances. In such a formulation, the requirement of gauge\ninvariance for the current is satisfied automatically. Moreover, one can judge\nunambiguously what quantities can be measured in the transport experiment.",
        "positive": "Large-Scale Arrays of Single- and Few-Layer MoS2 Nanomechanical\n  Resonators: We report on fabrication of large-scale arrays of suspended molybdenum\ndisulfide (MoS2) atomic layers, as two-dimensional (2D) MoS2 nanomechanical\nresonators. We employ a water-assisted lift-off process to release chemical\nvapor deposited (CVD) MoS2 atomic layers from a donor substrate, followed by an\nall-dry transfer onto microtrench arrays. The resultant large arrays of\nsuspended single- and few-layer MoS2 drumhead resonators (0.5 to 2um in\ndiameter) offer fundamental resonances (f_0) in the very high frequency (VHF)\nband (up to ~120MHz) and excellent figures-of-merit up to f_0*Q ~ 3*10^10Hz. A\nstretched circular diaphragm model allows us to estimate low pre-tension levels\nof typically ~15mN/m in these devices. Compared to previous approaches, our\ntransfer process features high yield and uniformity with minimal liquid and\nchemical exposure (only involving DI water), resulting in high-quality MoS2\ncrystals and exceptional device performance and homogeneity; and our process is\nreadily applicable to other 2D materials."
    },
    {
        "anchor": "The Geometrical Effects on Electronic Spectrum and Persistent Currents\n  in Mesoscopic Polygon: In this paper, a new mesoscopic polygon which possesses smooth transition at\nits corners is proposed. Because of the particularity of structure, this kind\nof mesoscopic polygon can also be a geometrical supperlattice. The geometrical\neffects on the electron states and persistent current are investigated\ncomprehensively in the presence of magnetic flux. We find that the particular\ngeometric structure of the polygon induces an effective periodic potential\nwhich results in gaps in the energy spectrum. The changes of gaps show the\nconsistency with the geometrical twoness of this new polygon. This electronic\nstructure and the corresponding physical properties are found to be periodic\nwith period $\\phi_{0}$ in the magnetic flux $\\phi $ and can be controlled by\nthe geometric method. We also consider the Rahsba spin-orbit interaction which\nmake the energy levels splitting newly to double and leads to an additional\nsmall zigzag in one period of the persistent current. These new phenomena may\nbe useful for the applications in quantum device design in the future.",
        "positive": "Dynamics of a large-spin-boson system in the strong coupling regime: We investigate collective effects of an ensemble of biased two level systems\ninteracting with a bosonic bath in the strong coupling regime. The two level\nsystems are described by a large pseudo-spin J. An equation for the expectation\nvalue M(t) of the z-component of the pseudo spin is derived and solved\nnumerically for an ohmic bath at T=0. In case of a large cut-off frequency of\nthe spectral function, a Markov approximation is justified and an analytical\nsolution is presented. We find that M(t) relaxes towards a highly correlated\nstate with maximum value $\\pm J$ for large times. However, this relaxation is\nextremely slow for most parameter values so as if the system was \"frozen in\" by\ninteraction with the bosonic bath."
    },
    {
        "anchor": "Quantum Phenomena in Low-Dimensional Systems: A brief summary of the physics of low-dimensional quantum systems is given.\nThe material should be accessible to advanced physics undergraduate students.\nReferences to recent review articles and books are provided when possible.",
        "positive": "Electron-electron scattering effect on spin relaxation in multi-valley\n  nanostructures: We develop a theory of effects of electron-electron collisions on the\nDyakonov-Perel' spin relaxation in multi-valley quantum wells. It is shown that\nthe electron-electron scattering rate which governs the spin relaxation is\ndifferent from that in a single-valley system. The theory is applied to Si/SiGe\n(001)-grown quantum wells where two valleys are simultaneously populated by\nfree carriers. The dependences of the spin relaxation rate on temperature,\nelectron concentration and valley-orbit splitting are calculated and discussed.\nWe demonstrate that in a wide range of temperatures the electron-electron\ncollisions can govern spin relaxation in high-quality Si/SiGe quantum wells."
    },
    {
        "anchor": "Temperature-dependent 2D-3D growth transition of ultra-thin Pt films\n  deposited by PLD: During the growth of metal thin films on dielectric substrates at a given\ndeposition temperature T, the film's morphology is conditioned by the magnitude\nand asymmetry of up- and downhill diffusion. Any severe change of this\nmechanism leads to a growth instability, which induces an alteration of the\nthin film morphology. In order to study this mechanism, ultra-thin Pt films\nwere deposited via pulsed laser deposition (PLD) onto\nyttria-stabilized-zirconia single crystals at different deposition\ntemperatures. The morphological evolution of Pt thin films has been\ninvestigated by means of scanning electron microscopy (SEM), atomic force\nmicroscopy (AFM) and standard image analysis techniques. The experimentally\nobtained morphologies are compared to simulated thin film structures resulting\nfrom a two-dimensional kinetic Monte Carlo (KMC) approach. Two main\nobservations have been made: i) Thin Pt films deposited onto zirconia undergo a\ngrowth transition from two-dimensional to three-dimensional growth at T > 573\nK. The growth transition and related morphological changes are a function of\nthe deposition temperature. ii) A critical cluster size of i\\ast = 4 in\ncombination with an asymmetric Ehrlich-Schwoebel (ES) barrier favoring the\nuphill diffusion of atoms allows for a computational reproduction of the\nexperimentally obtained film morphologies.",
        "positive": "High-cooperativity coupling of a rare-earth spin ensemble to a\n  superconducting resonator using yttrium orthosilicate as a substrate: Yttrium orthosilicate (Y$_2$SiO$_5$, or YSO) has proved to be a convenient\nhost for rare-earth ions used in demonstrations of microwave quantum memories\nand optical memories with microwave interfaces, and shows promise for coherent\nmicrowave--optical conversion owing to its favourable optical and spin\nproperties. The strong coupling required by such microwave applications could\nbe achieved using superconducting resonators patterned directly on\nY$_2$SiO$_5$, and hence we investigate here the use of Y$_2$SiO$_5$ as an\nalternative to sapphire or silicon substrates for superconducting hybrid device\nfabrication. A NbN resonator with frequency 6.008 GHz and low power quality\nfactor $Q \\approx 400000$ was fabricated on a Y$_2$SiO$_5$ substrate doped with\nisotopically enriched Nd$^{145}$. Measurements of dielectric loss yield a\nloss-tangent $\\tan\\delta = 4 \\times 10^{-6}$, comparable to sapphire. Electron\nspin resonance (ESR) measurements performed using the resonator show the\ncharacteristic angular dependence expected from the anisotropic Nd$^{145}$\nspin, and the coupling strength between resonator and electron spins is in the\nhigh cooperativity regime ($C = 30$). These results demonstrate Y$_2$SiO$_5$ as\nan excellent substrate for low-loss, high-Q microwave resonators, especially in\napplications for coupling to optically-accessible rare earth spins."
    },
    {
        "anchor": "Improved position measurement of nano electromechanical systems using\n  cross correlations: We consider position measurements using the cross-correlated output of two\ntunnel junction position detectors. Using a fully quantum treatment, we\ncalculate the equation of motion for the density matrix of the coupled\ndetector-detector-mechanical oscillator system. After discussing the presence\nof a bound on the peak-to-background ratio in a position measurement using a\nsingle detector, we show how one can use detector cross correlations to\novercome this bound. We analyze two different possible experimental\nrealizations of the cross correlation measurement and show that in both cases\nthe maximum cross-correlated output is obtained when using twin detectors and\napplying equal bias to each tunnel junction. Furthermore, we show how the\ndouble-detector setup can be exploited to drastically reduce the added\ndisplacement noise of the oscillator.",
        "positive": "Extending ballistic graphene FET lumped element models to diffusive\n  devices: In this work, a modified, lumped element graphene field effect device model\nis presented. The model is based on the \"Top-of-the-barrier\" approach which is\nusually valid only for ballistic graphene nanotransistors. Proper modifications\nare introduced to extend the model's validity so that it accurately describes\nboth ballistic and diffusive graphene devices. The model is compared to data\nalready presented in the literature. It is shown that a good agreement is\nobtained for both nano-sized and large area graphene based channels. Accurate\nprediction of drain current and transconductance for both cases is obtained."
    },
    {
        "anchor": "Adiabatic quantum pumping of chiral Majorana fermions: We investigate adiabatic quantum pumping of chiral Majorana states in a\nsystem composed of two Mach--Zehnder type interferometers coupled via a quantum\npoint contact. The pumped current is generated by periodic modulation of the\nphases accumulated by traveling around each interferometer. Using scattering\nmatrix formalism we show that the pumped current reveals a definite signature\nof the chiral nature of the Majorana states involved in transport in this\ngeometry. Furthermore, by tuning the coupling between the two interferometers\nthe pump can operate in a regime where finite pumped current and zero\ntwo-terminal conductance is expected.",
        "positive": "Direct observation of individual charges and their dynamics on graphene\n  by low-energy electron holography: Visualizing individual charges confined to molecules and observing their\ndynamics with high spatial resolution is a challenge for advancing various\nfields in science, ranging from mesoscopic physics to electron transfer events\nin biological molecules. We show here, that the high sensitivity of low-energy\nelectrons to local electric fields can be employed to directly visualize\nindividual charged adsorbates and to study their behaviour in a quantitative\nway. This makes electron holography a unique probing tool for directly\nvisualising charge distributions with a sensitivity of a fraction of an\nelementary charge. Moreover, spatial resolution in the nanometer range and fast\ndata acquisition inherent to lens-less low-energy electron holography allows\nfor direct visual inspection of charge transfer processes."
    },
    {
        "anchor": "Andreev reflection of quantum Hall states through a quantum point\n  contact: We investigate the interplay between the quantum Hall (QH) effect and\nsuperconductivity in InAs surface quantum well (SQW)/NbTiN heterostructures\nusing a quantum point contact (QPC). We use QPC to control the proximity of the\nedge states to the superconductor. By measuring the upstream and downstream\nresistances of the device, we investigate the efficiency of Andreev conversion\nat the InAs/NbTiN interface. Our experimental data is analyzed using the\nLandauer-Buttiker formalism, generalized to allow for Andreev reflection\nprocesses. We show that by varying the voltage of the QPC, $V_{QPC}$, the\naverage Andreev reflection, $A$, at the QH-SC interface can be tuned from 50%\nto 10%. The evolution of $A$ with $V_{QPC}$ extracted from the measurements\nexhibits plateaus separated by regions for which $A$ varies continuously with\n$V_{QPC}$. The presence of plateaus suggests that for some ranges of $V_{QPC}$\nthe QPC might be pinching off almost completely from the QH-SC interface some\nof the edge modes. Our work shows a new experimental setup to control and\nadvance the understanding of the complex interplay between superconductivity\nand QH effect in two-dimensional electron gas systems.",
        "positive": "Electronic viscosity and energy relaxation in neutral graphene: We explore hydrodynamics of Dirac fermions in neutral graphene in the Corbino\ngeometry. In the absence of magnetic field, the bulk Ohmic charge flow and the\nhydrodynamic energy flow are decoupled. However, the energy flow does affect\nthe overall resistance of the system through viscous dissipation and energy\nrelaxation that has to be compensated by the work done by the current source.\nSolving the hydrodynamic equations, we find that local temperature and electric\npotential are discontinuous at the interfaces with the leads as well as the\ndevice resistance and argue that this makes Corbino geometry a feasible choice\nfor an experimental observation of the Dirac fluid."
    },
    {
        "anchor": "Overbias Light Emission From Memristive Nanojunctions: A nanoscale dielectric gap clamped between two metal electrodes may undergo a\nlarge resistance change from insulating to highly conducting upon applying an\nelectrical stress. This sudden resistive switching effect is largely exploited\nin memristors for emulating synapses in neuromorphic neural networks. Here, we\nshow that resistive switching can be accompanied by a release of\nelectromagnetic radiation spanning the visible spectral region. Importantly, we\nfind that the spectrum is characterized by photon energies exceeding the\nmaximum kinetic energy of electrons provided by the switching voltage. This\nso-called overbias emission can be described self-consistently by a thermal\nradiation model featuring an out-of-equilibrium electron distribution generated\nin the device with an effective temperature exceeding 2000~K. The emitted\nspectrum is understood in terms of hot electrons radiatively decaying to\nresonant optical modes occurring in a nanoscale \\ch{SiO2} matrix located\nbetween two \\ch{Ag} electrodes. The correlation between resistive switching and\nthe onset of overbias emission in atomic-scale photonic memristor brings new\nvenues to generate light on chip and their exploitation in optical\ninterconnects. Photons emitted during memristive switching can also be\nmonitored to follow the neural activation pathways in memristor-based networks.",
        "positive": "A multideterminant assessment of mean field methods for the description\n  of electron transfer in the weak coupling regime: Multideterminant calculations have been performed on model systems to\nemphasize the role of many-body effects in the general description of charge\nquantization experiments. We show numerically and derive analytically that a\nclosed-shell ansatz, the usual ingredient of mean-field methods, does not\nproperly describe the step-like electron transfer characteristic in weakly\ncoupled systems. With the multideterminant results as a benchmark, we have\nevaluated the performance of common ab initio mean field techniques, such as\nHartree Fock (HF) and Density Functional Theory (DFT) with local and hybrid\nexchange correlation functionals, with a special focus on spin-polarization\neffects. For HF and hybrid DFT, a qualitatively correct open-shell solution\nwith distinct steps in the electron transfer behaviour can be obtained with a\nspin-unrestricted (i.e., spin-polarized) ansatz though this solution differs\nquantitatively from the multideterminant reference. We also discuss the\nrelationship between the electronic eigenvalue gap and the onset of charge\ntransfer for both HF and DFT and relate our findings to recently proposed\npractical schemes for calculating the addition energies in the Coulomb blockade\nregime for single molecule junctions from closed-shell DFT within the local\ndensity approximation."
    },
    {
        "anchor": "Anomalous polarization dependence of Raman scattering and\n  crystallographic orientation of black phosphorus: We investigated polarization dependence of the Raman modes in black\nphosphorus (BP) using five different excitation wavelengths. The\ncrystallographic orientation was determined by comparing polarized optical\nmicroscopy with high-resolution transmission electron microscope analysis. In\npolarized Raman spectroscopy, the B2g mode shows the same polarization\ndependence regardless of the excitation wavelength or the sample thickness. On\nthe other hand, the Ag1 and Ag2 modes show a peculiar polarization behavior\nthat depends on the excitation wavelength and the sample thickness. The\nthickness dependence can be explained by considering the anisotropic\ninterference effect due to birefringence and dichroism of the BP crystal, but\nthe wavelength dependence cannot be explained. We propose a simple and\nfail-proof procedure to determine the orientation of a BP crystal by combining\npolarized Raman scattering with polarized optical microscopy.",
        "positive": "Effective screening of medium-assisted Van der Waals interactions\n  between embedded particles: The effect of an implicit medium on dispersive interactions of particle pairs\nis discussed and simple expressions for the correction relative to vacuum are\nderived. We show that a single point Gauss quadrature leads to the intuitive\nresult that the vacuum van der Waals $C_6$ coefficient is screened by the\npermittivity squared of the environment evaluated near to the resonance\nfrequencies of the interacting particles. This approximation should be\nparticularly relevant if the medium is transparent at these frequencies. In the\nmanuscript, we provide simple models and sets of parameters for commonly used\nsolvents, atoms and small molecules."
    },
    {
        "anchor": "Comment on \"Piezoelectricity in planar boron nitride via a geometric\n  phase\": Using the strain-dependent effective Hamiltonian and the geometric phase,\nDroth et al. [Phys. Rev. B 94, 075404 (2016)] obtain an analytical expression\nfor the electronic contribution to the piezoelectricity of planar hexagonal\nboron nitride (h -BN). Their analytical results of piezoelectric constants for\nh -BN are invalid because of the mistakes in constructing the adiabatic process\nof the piezoelectricity. In this comment, we reconstruct a proper adiabatic\nprocess for piezoelectricity and formulate a general Berry phase expression for\nthe piezoelectric coefficients of two-dimensional piezoelectric crystals by\nmeans of the modern theory of polarization. The corrected analytical results of\nthe piezoelectric constants are in complete consistency with the\nfirst-principles calculations and hence manifest the validity and generality of\nthe Berry phase expression of piezoelectric coefficients.",
        "positive": "Magneto-optical conductivity of double Weyl semimetals: We investigate the magneto-optical response of double Weyl semimetals whose\nenergy dispersion is intrinsically anisotropic. We find that in the presence of\na magnetic field, the most salient feature of the optical conductivity is a\nseries of resonant peaks with the corresponding frequencies scaling linearly\nwith the strength of the magnetic field. In addition, the optical conductivity\nis found to be anisotropic, with two of the three longitudinal components\nresiding at a linear background and the remaining one at a constant background.\nThe effects of chemical potential, temperature, impurity scattering, and\nparticle-hole symmetry breaking on the optical conductivity are also studied."
    },
    {
        "anchor": "Magnetic field effects on electron transport in nanoring with orbital\n  Rashba coupling: We study the effects of a Zeeman magnetic field on the electron transport of\none-dimensional quantum rings which are marked by electronic states with\n$d-$orbital symmetry in the presence of spin-orbit and orbital Rashba\ncouplings. By considering phase-coherent propagation, we analyse the geometric\nAharonov-Anandan (AA) phase of the channels which is acquired in a closed path,\nby demonstrating that the orbital polarization can influence the electronic\ntransport when amplitude and magnetic field directions are varied. We explore\nall the possible cases for the injection of electrons at various energies in\nthe regime of low electron filling. The magnetic field can allow the selection\nof only one channel where the transmission is uniquely affected by the AA\nphase. Conversely, when more orbital channels are involved there is also a\ndynamical contribution that lead to oscillations in the transmission as the\nmagnetic field is varied. In particular, the transmission is chiral when the\nenergy states are close to the absolute minimum of the energy bands. Instead,\nwhen an interference between the channels occurs the orbital and spin\ncontributions tend to balance each other with the increasing of the magnetic\nfield amplitude resulting in a trivial AA phase. This saturation effect does\nnot occur in the high magnetic field regime when orbital and spin properties of\nthe channels exhibit sharp variations with direct consequences on the\ntransport.",
        "positive": "Carrier Multiplication via Photocurrent Measurements in Dual-Gated\n  MoTe_2: Although van der Waals layered transition metal dichalcogenides from\ntransient absorption spectroscopy have successfully demonstrated an ideal\ncarrier multiplication (CM) performance with an onset of nearly\n2Eg,interpretation of the CM effect from the optical approach remains\nunresolved owing to the complexity of many-body electron-hole pairs. We\ndemonstrate the CM effect through simple photocurrent measurements by\nfabricating the dual-gate P-N junction of a MoTe2 film on a transparent\nsubstrate. Electrons and holes were efficiently extracted by eliminating the\nSchottky barriers in the metal contact and minimizing multiple reflections. The\nphotocurrent was elevated proportionately to the excitation energy. The boosted\nquantum efficiency confirms the multiple electron-hole pair generation of >2Eg,\nconsistent with CM results from an optical approach, pushing the solar cell\nefficiency beyond the Shockley-Queisser limit."
    },
    {
        "anchor": "Shaping excitons in light-harvesting proteins through nanoplasmonics: Nanoplasmonics has been used to enhance molecular spectroscopic signals, with\nexquisite spatial resolution down to the sub-molecular scale. By means of a\nrigorous, state-of-the-art multiscale model based on a quantum chemical\ndescription, here we show that optimally tuned tip-shaped metal nanoparticles\ncan selectively excite localized regions of typically coherent systems,\neventually narrowing down to probing one single pigment. The well-known major\nlight-harvesting complex LH2 of purple bacteria has been investigated because\nof its unique properties, as it presents both high and weak delocalization\namong subclusters of pigments. This finding opens the way to the direct\nspectroscopic investigation of quantum-based processes, such as the quantum\ndiffusion of the excitation among the chromophores, and their external\nmanipulation",
        "positive": "Vacancy in graphene: insight on magnetic properties from theoretical\n  modeling: Magnetic properties of a single vacancy in graphene is a relevant and still\nmuch discussed problem. The experimental results point to a clearly detectable\nmagnetic defect state at the Fermi energy, while calculations based on density\nfunctional theory (DFT) yield widely varying results for the magnetic moment,\nin the range of $\\mu=1.04-2.0$ $\\mu_{B}$. We present a multi-tool \\textit{ab\ninitio} theoretical study of the same defect, using two simulation protocols\nfor a defect in a crystal (cluster and periodic boundary conditions) and\ndifferent DFT functionals - bare and hybrid DFT, mixing a fraction of\nHartree-Fock exchange (XC). Our main conclusions are two-fold: First, we find\nthat due to the $\\pi$-character of the Fermi-energy states of graphene,\ninclusion of XC is crucial and for a single isolated vacancy we can predict an\ninteger magnetic moment $\\mu=2\\mu_{B}$. Second, we find that due to the\nspecific symmetry of the graphene lattice, periodic arrays of single vacancies\nmay provide interesting diffuse spin-spin interactions."
    },
    {
        "anchor": "Universal zero-bias conductance through a quantum wire side-coupled to a\n  quantum dot: A numerical renormalization-group study of the conductance through a quantum\nwire side-coupled to a quantum dot is reported. The temperature and the\ndot-energy dependence of the conductance are examined in the light of a\nrecently derived linear mapping between the Kondo-regime temperature-dependent\nconductance and the universal function describing the conductance for the\nsymmetric Anderson model of a quantum wire with an embedded quantum dot. Two\nconduction paths, one traversing the wire, the other a bypass through the\nquantum dot, are identified. A gate potential applied to the quantum wire is\nshown to control the flow through the bypass. When the potential favors\ntransport through the wire, the conductance in the Kondo regime rises from\nnearly zero at low temperatures to nearly ballistic at high temperatures. When\nit favors the dot, the pattern is reversed: the conductance decays from nearly\nballistic to nearly zero. When the fluxes through the two paths are comparable,\nthe conductance is nearly temperature-independent in the Kondo regime, and a\nFano antiresonance in the fixed-temperature plot of the conductance as a\nfunction of the dot energy signals interference. Throughout the Kondo regime\nand, at low temperatures, even in the mixed-valence regime, the numerical data\nare in excellent agreement with the universal mapping.",
        "positive": "Berry-curvature-induced linear magnetotransport in magnetic Weyl\n  semimetals: Magnetotransport such as the giant magnetoresistance and Hall effect lies at\nthe heart of fundamental physics and technologies. Recently, some experiments\nhave clearly demonstrated linear magnetotransport (LMT) proportional to\nmagnetic field but the underlying physical mechanism is still unclear. In this\nwork, we show that Berry curvature effect is a new mechanism dominating the\nLMT. The Berry-curvature-induced LMT widely exists in 66 out of 122 magnetic\npoint groups. For typical magnetic Weyl semimetals Co$_3$Sn$_2$S$_2$ and\nferromagnetic MnBi$_2$Te$_4$, Berry curvature induces LMT conductivities\nreaching orders of $10^4$ and $10^2$ ${\\rm \\Omega^{-1}m^{-1}}$ per tesla,\nrespectively, which are tunable through magnetization canting induced by\nmoderate magnetic fields. We further reveal that Berry-curvature-induced LMT\ncan be detected by Hall effect and especially intrinsic magnetoresistance\nexceeding $100\\%$ per tesla insensitive to the sample quality. Our results\nagree with recent experiments and uncover the important role of Berry curvature\nin LMT."
    },
    {
        "anchor": "Conductivity of suspended graphene at the Dirac point: We study transport properties of clean suspended graphene at the Dirac point.\nIn the absence of the electron-electron interaction, the main contribution to\nresistivity comes from interaction with flexural (out-of-plane deformation)\nphonons. We find that the phonon-limited conductivity scales with the\ntemperature as $T^{-\\eta}, $ where $\\eta$ is the critical exponent (equal to\n$\\approx 0.7$ according to numerical studies) describing renormalization of the\nflexural phonon correlation functions due to anharmonic coupling with the\nin-plane phonons. The electron-electron interaction induces an additional\nscattering mechanism and also affects the electron-phonon scattering by\nscreening the deformation potential. We demonstrate that the combined effect of\nboth interactions results in a conductivity that can be expressed as a\ndimensionless function of two temperature-dependent dimensionless constants,\n$G[T]$ and $G_e[T]$ which characterize the strength of electron-phonon and\nelectron-electron interaction, respectively. We also discuss the behavior of\nconductivity away from the Dirac point as well as the role of the impurity\npotential and compare our predictions with available experimental data.",
        "positive": "Probing optical spin-currents using THz spin-waves in noncollinear\n  magnetic bilayers: Optically induced spin currents have proven to be useful in spintronics\napplications, allowing for sub-ps all-optical control of magnetization.\nHowever, the mechanism responsible for their generation is still heavily\ndebated. Here we use the excitation of spin-current induced THz spin-waves in\nnoncollinear bilayer structures to directly study optical spin-currents in the\ntime domain. We measure a significant laser-fluence dependence of the spin-wave\nphase, which can quantitatively be explained assuming the spin current is\nproportional to the time derivative of the magnetization. Measurements of the\nabsolute spin-wave phase, supported by theoretical calculations and\nmicromagnetic simulations, suggest that a simple ballistic transport picture is\nsufficient to properly explain spin transport in our experiments and that the\ndamping-like optical STT dominates THz spin-wave generation. Our findings\nsuggest laser-induced demagnetization and spin-current generation share the\nsame microscopic origin."
    },
    {
        "anchor": "Distinct chemistries explain decoupling of slip and wettability in\n  atomically smooth aqueous interfaces: Despite essentially identical crystallography and equilibrium structuring of\nwater, nanoscopic channels composed of hexagonal boron nitride and graphite\nexhibit an order-of-magnitude difference in fluid slip. We investigate this\ndifference using molecular dynamics simulations, demonstrating that its origin\nis in the distinct chemistries of the two materials. In particular, the\npresence of polar bonds in hexagonal boron nitride, absent in graphite, leads\nto Coulombic interactions between the polar water molecules and the wall. We\ndemonstrate that this interaction is manifested in a large typical lateral\nforce experienced by a layer of oriented hydrogen atoms in the vicinity of the\nwall, leading to the enhanced friction in hexagonal boron nitride. The fluid\nadhesion to the wall is dominated by dispersive forces in both materials,\nleading to similar wettabilities. Our results rationalize recent observations\nthat the difference in frictional characteristics of graphite and hexagonal\nboron nitride cannot be explained on the basis of the minor differences in\ntheir wettabilities.",
        "positive": "Control and Characterization of Individual Grains and Grain Boundaries\n  in Graphene Grown by Chemical Vapor Deposition: The strong interest in graphene has motivated the scalable production of high\nquality graphene and graphene devices. Since large-scale graphene films\nsynthesized to date are typically polycrystalline, it is important to\ncharacterize and control grain boundaries, generally believed to degrade\ngraphene quality. Here we study single-crystal graphene grains synthesized by\nambient CVD on polycrystalline Cu, and show how individual boundaries between\ncoalescing grains affect graphene's electronic properties. The graphene grains\nshow no definite epitaxial relationship with the Cu substrate, and can cross Cu\ngrain boundaries. The edges of these grains are found to be predominantly\nparallel to zigzag directions. We show that grain boundaries give a significant\nRaman \"D\" peak, impede electrical transport, and induce prominent weak\nlocalization indicative of intervalley scattering in graphene. Finally, we\ndemonstrate an approach using pre-patterned growth seeds to control graphene\nnucleation, opening a route towards scalable fabrication of single-crystal\ngraphene devices without grain boundaries."
    },
    {
        "anchor": "Dynamics of a suspended nanowire driven by an ac Josephson current in an\n  inhomogeneous magnetic field: We consider a voltage-biased nanoelectromechanical Josephson junction, where\na suspended nanowire forms a superconducting weak-link, in an inhomogeneous\nmagnetic field. We show that a nonlinear coupling between the Josephson current\nand the magnetic field generates a Laplace force that induces a whirling motion\nof the nanowire. By performing an analytical and a numerical analysis, we\ndemonstrate that at resonance, the amplitude-phase dynamics of the whirling\nmovement present different regimes depending on the degree of inhomogeneity of\nthe magnetic field: time independent, periodic and chaotic. Transitions between\nthese regimes are also discussed.",
        "positive": "Energy fluctuations of finite free-electron Fermi gas: We discuss the energy distribution of free-electron Fermi-gas, a problem with\na textbook solution of Gaussian energy fluctuations in the limit of a large\nsystem. We find that for a small system, characterized solely by its heat\ncapacity $C$, the distribution can be solved analytically, and it is both\nskewed and it vanishes at low energies, exhibiting a sharp drop to zero at the\nenergy corresponding to the filled Fermi sea. The results are relevant from the\nexperimental point of view, since the predicted non-Gaussian effects become\npronounced when $C/k_B \\lesssim 10^3$ ($k_B$ is the Boltzmann constant), a\nregime that can be easily achieved for instance in mesoscopic metallic\nconductors at sub-kelvin temperatures."
    },
    {
        "anchor": "Optically Driven Magnetic Phase Transition of Monolayer RuCl3: Strong light-matter interactions within nanoscale structures offer the\npossibility of optically controlling material properties. Motivated by the\nrecent discovery of intrinsic long-range magnetic order in two-dimensional\nmaterials, which allows for the creation of novel magnetic devices of\nunprecedented small size, we predict that light can couple with magnetism and\nefficiently tune magnetic orders of monolayer ruthenium trichloride (RuCl3).\nFirst-principles calculations show that both free carriers and optically\nexcited electron-hole pairs can switch monolayer RuCl3 from the proximate\nspin-liquid phase to a stable ferromagnetic phase. Specifically, a moderate\nelectron-hole pair density (on the order of 10^13 cm-2) can significantly\nstabilize the ferromagnetic phase by 10 meV/f.u. in comparison to the zigzag\nphase, so that the predicted ferromagnetism can be driven by optical pumping\nexperiments. Analysis shows that this magnetic phase transition is driven by a\ncombined effect of doping-induced lattice strain and itinerant ferromagnetism.\nAccording to the Ising-model calculation, we find that the Curie temperature of\nthe ferromagnetic phase can be increased significantly by raising carrier or\nelectron-hole pair density. This enhanced opto-magnetic effect opens new\nopportunities to manipulate two-dimensional magnetism through non-contact,\noptical approaches.",
        "positive": "Quantum States of a Skyrmion in a 2D Antiferromagnet: Quantum states of a skyrmion in a 2D antiferromagnetic lattice are obtained\nby quantizing the scaling parameter of Belavin-Polyakov model. Skyrmion\nclassical collapse due to violation of the translational invariance of the\ncontinuous spin-field model by the lattice is replaced in quantum mechanics by\ntransitions between discrete energy levels of the skyrmion. Rates of\ntransitions due to the emission of magnons are computed. Ways of detecting\nquantization of skyrmion states are discussed."
    },
    {
        "anchor": "Giant resonant skew scattering of plasma waves in graphene off a\n  micromagnet: Electron skew scattering by impurities is one of the major mechanisms behind\nthe anomalous Hall effect in ferromagnetic nanostructures. It is particularly\nstrong at the surface of topological insulators where the Dirac equation\ngoverns electron dynamics. Motivated by recently discovered mappings between\nhydrodynamics and spin-1 Dirac equations, we consider the scattering of plasma\nwaves -- propagating charge density oscillations -- excited in graphene off a\nnon-uniform magnetic field created by an adjacent circular micromagnet. The\ncalculated scattering amplitude not only exhibits a giant asymmetry, or\nskewness, but is resonantly enhanced if the frequency of the incoming wave\nmatches the frequency of the trapped mode circulating the micromagnet in only\none direction. Furthermore, if the frequency of incoming waves exceeds the\nLarmor frequency, the angular distribution of scattered plasma waves is\nindistinguishable from the one of Dirac electrons at the surface of a\ntopological insulator scattering off a magnetic impurity. The micrometer scale\nof the proposed setup enables direct investigations of individual skew\nscattering events previously inaccessible in electronic systems.",
        "positive": "Thermionic charge transport in CMOS nano-transistors: We report on DC and microwave electrical transport measurements in\nsilicon-on-insulator CMOS nano-transistors at low and room temperature. At low\nsource-drain voltage, the DC current and RF response show signs of conductance\nquantization. We attribute this to Coulomb blockade resulting from barriers\nformed at the spacer-gate interfaces. We show that at high bias transport\noccurs thermionically over the highest barrier: Transconductance traces\nobtained from microwave scattering-parameter measurements at liquid helium and\nroom temperature is accurately fitted by a thermionic model. From the fits we\ndeduce the ratio of gate capacitance and quantum capacitance, as well as the\nelectron temperature."
    },
    {
        "anchor": "Optical Snake States in Photonic Graphene: We propose an optical analogue of electron snake states based on artificial\ngauge magnetic field in photonic graphene with effective strain implemented by\nvarying distance between pillars. We develop an intuitive and exhaustive\ncontinuous model based on tight-binding approximation and compare it with\nnumerical simulations of a realistic photonic structure. The allowed lateral\npropagation direction is shown to be strongly coupled to the valley degree of\nfreedom and the proposed photonic structure may be used a valley filter.",
        "positive": "Field effect and local gating in nitrogen-terminated nanopores (NtNP)\n  and nanogaps (NtNG) in graphene: Single-molecule biosensing, with a promise of being applied in protein and\nDNA sequencing, could be achieved using tunneling current approach.\nElectrode-molecule-electrode tunneling current critically depends on whether\nmolecular levels contribute to electronic transport or not. Here we found\nemploying DFT and Non-Equilibrium Green's Function formalism that energies of\nbenzene molecular levels placed between graphene electrodes are strongly\ninfluenced by electrode termination. Termination-dependent dipoles formed at\nthe electrode ends induce in-gap field effect that is responsible for shifting\nof molecular levels. We show that the HOMO is closest to Fermi energy for\nnitrogen-terminated nanogaps (NtNGs) and nanopores (NtNPs), promoting them as\nstrong candidates for single-molecule sensing applications."
    },
    {
        "anchor": "Effects of Domain Wall on Electronic Transport Properties in Mesoscopic\n  Wire of Metallic Ferromagnets: We study the effect of the domain wall on electronic transport properties in\nwire of ferromagnetic 3$d$ transition metals based on the linear response\ntheory. We considered the exchange interaction between the conduction electron\nand the magnetization, taking into account the scattering by impurities as\nwell. The effective electron-wall interaction is derived by use of a local\ngauge transformation in the spin space. This interaction is treated\nperturbatively to the second order. The conductivity contribution within the\nclassical (Boltzmann) transport theory turns out to be negligiblly small in\nbulk magnets, due to a large thickness of the wall compared with the fermi\nwavelength. It can be, however, significant in ballistic nanocontacts, as\nindicated in recent experiments. We also discuss the quantum correction in\ndisordered case where the quantum coherence among electrons becomes important.\nIn such case of weak localization the wall can contribute to a decrease of\nresistivity by causing dephasing. At lower temperature this effect grows and\ncan win over the classical contribution, in particular in wire of diameter\n$L_{\\perp}\\lesssim \\ell_{\\phi}$, $\\ell_{\\phi}$ being the inelastic diffusion\nlength. Conductance change of the quantum origin caused by the motion of the\nwall is also discussed.",
        "positive": "Hall effect in ferromagnetic nanomagnets: magnetic field dependence as\n  an evidence of inverse spin Hall effect contribution: We measure magnetic field dependence of the Hall angle in a metallic\nferromagnetic nanomagnet with stable local magnetic moments where the adopted\nmechanisms of Hall effect predict linear plus a constant dependence on the\nexternal field originating from the ordinary and anomalous Hall effects,\nrespectively. We suggest that the experimentally observed deviations from this\ndependence is caused by the inverse spin Hall effect (ISHE) and develop a\nphenomenological theory, which predicts a unique nonlinear dependence of the\nISHE contribution on the external magnetic field. Perfect agreement between\ntheory and experiment supports the considerable role of the ISHE in the Hall\ntransport in ferromagnetic metals."
    },
    {
        "anchor": "Breakdown of classical electrostatics in the depolarization of quantum\n  wires and nanotubes: In quantum wires, such as metallic nanotubes, the optical absorption of the\ntransverse polarization is controlled by the depolarization effect which stems\nfrom the redistribution of conduction electrons around the circumference of the\nsystem. The traditional electrostatics treatment of the depolarization effect\nrelies on approximating the system by a cylinder with some effective dielectric\npermittivity. We demonstrate that this simple intuitive picture does not\nadequately describe optical absorption near its threshold, as the\ndepolarization effect becomes dominated by many-body correlations which\nstrongly modify the spectral dependence of absorption.",
        "positive": "Can half metallic zincblende MnAs be grown?: In this paper we investigate theoretically the ground state NiAs-type\nstructure of MnAs and we compare the magnetic and structural properties with an\nhypothetical zincblende structure. A zincblende structure can be obtained, in\nprinciple, from the diluted magnetic semiconductor Ga$_{1-x}$Mn$_x$As in the\nlimit $x=1$. Using density functional calculations within the local\nspin-density approximation (LSDA), we show that the zincblende structure,\nalthough showing half metallic behavior which is very attractive for\nspintronics, can not be stabilized at equilibrium. We perform a tight-binding\nanalysis of the Mn-As bond in the tetrahedral coordination to investigate the\nnature of the bonding in diluted magnetic semiconductors."
    },
    {
        "anchor": "Microwave signatures of $\\mathbb{Z}_{2}$ and $\\mathbb{Z}_{4}$ fractional\n  Josephson effects: We present a many-body exact diagonalization study of the $\\mathbb{Z}_2$ and\n$\\mathbb{Z}_4$ Josephson effects in circuit quantum electrodynamics\narchitectures. Numerical simulations are conducted on Kitaev chain Josephson\njunctions hosting nearest-neighbor Coulomb interactions. The low-energy\neffective theory of highly transparent Kitaev chain junctions is shown to be\nidentical to that of junctions created at the edge of a quantum spin-Hall\ninsulator. By capacitively coupling the interacting junction to a microwave\nresonator, we predict signatures of the fractional Josephson effects on the\ncavity frequency and on time-resolved reflectivity measurements.",
        "positive": "Topological classification with additional symmetries from Clifford\n  algebras: We classify topological insulators and superconductors in the presence of\nadditional symmetries such as reflection or mirror symmetries. For each member\nof the 10 Altland-Zirnbauer symmetry classes, we have a Clifford algebra\ndefined by operators of the generic (time-reversal, particle-hole, or chiral)\nsymmetries and additional symmetries, together with gamma matrices in Dirac\nHamiltonians representing topological insulators and superconductors. Following\nKitaev's approach, we classify gapped phases of non-interacting fermions under\nadditional symmetries by examining all possible distinct Dirac mass terms which\ncan be added to the set of generators of the Clifford algebra. We find that\nimposing additional symmetries in effect changes symmetry classes and causes\nshifts in the periodic table of topological insulators and superconductors. Our\nresults are in agreement with the classification under reflection symmetry\nrecently reported by Chiu et al. Several examples are discussed including a\ntopological crystalline insulator with mirror Chern numbers and mirror\nsuperconductors."
    },
    {
        "anchor": "Nonlinear Dispersion Relation and Out-of-Plane Second Harmonic\n  Generation in MoSSe and WSSe Janus Monolayers: Janus transition metal dichalcogenides are an emerging class of atomically\nthin materials with engineered broken mirror symmetry that gives rise to\nlong-lived dipolar excitons, Rashba splitting, and topologically protected\nsolitons. They hold great promise as a versatile nonlinear optical platform due\nto their broadband harmonic generation tunability, ease of integration on\nphotonic structures, and nonlinearities beyond the basal crystal plane. Here,\nwe study second and third harmonic generation in MoSSe and WSSe Janus\nmonolayers. We use polarization-resolved spectroscopy to map the full\nsecond-order susceptibility tensor of MoSSe, including its out-of-plane\ncomponents. In addition, we measure the effective third-order susceptibility,\nand the second-order nonlinear dispersion close to exciton resonances for both\nMoSSe and WSSe at room and cryogenic temperatures. Our work sets a bedrock for\nunderstanding the nonlinear optical properties of Janus transition metal\ndichalcogenides and probing their use in the next-generation on-chip\nmultifaceted photonic devices.",
        "positive": "Atomic-resolution study of oxygen vacancy ordering in\n  $La_{0.5}$$Sr_{0.5}$Co$O_{3-\u03b4}$ thin films on SrTi$O_{3}$ during\n  in-situ cooling experiments: The presence of oxygen vacancy, as well as ordering of vacancies plays an\nimportant role in determining the electronic, ionic and thermal transport\nproperties of many transition metal oxide materials. Controlling the\nconcentration of oxygen vacancies as well as the structures or domains of\nordered oxygen vacancies has been the subject of many experimental and\ntheoretical studies. In epitaxial thin films, the concentration of oxygen\nvacancies as well as the type of ordering depends on the structure of the\nsupport as well as the lattice mismatch between the thin films and the support.\nThe role of temperature induced structural phase transitions on the oxygen\nvacancy ordering has remained largely unexplored. Here, we use\naberration-corrected scanning transmission electron microscopy (STEM) combined\nwith an in-situ cooling experiments to characterize the atomic/electronic\nstructures of oxygen-deficient $La_{0.5}$$Sr_{0.5}$Co$O_{3-{\\delta}}$ thin\nfilms grown on SrTi$O_{3}$ across the anti-ferrodistortive phase transition of\nSrTi$O_{3}$ at 105 K. We demonstrate that atomic-resolution imaging and\nelectron energy-loss spectroscopy (EELS) can be used to examine variations in\nthe local density of states as a function of sample temperature and thus of the\nstructure of the support."
    },
    {
        "anchor": "Epitaxial metals for interconnects beyond Cu: The experimentally measured resistivity of Co(0001) and Ru(0001) single\ncrystal thin films, grown on c-plane sapphire substrates, as a function of\nthickness is modeled using the semiclassical model of Fuchs-Sondheimer. The\nmodel fits show that the resistivity of Ru would cross below that for Co at a\nthickness of approximately 20 nm. For Ru films with thicknesses above 20 nm,\ntransmission electron microscopy evidences threading and misfit dislocations,\nstacking faults and deformation twins. Exposure of Co films to ambient air, and\nthe deposition of oxide layers of SiO2, MgO, Al2O3 and Cr2O3 on Ru degrade the\nsurface specularity of the metallic layer. However, for the Ru films, annealing\nin a reducing ambient restores the surface specularity. Epitaxial\nelectrochemical deposition of Co on epitaxially-deposited Ru layers is used as\nan example to demonstrate the feasibility of generating epitaxial interconnects\nfor back-end of line structures. An electron transport model based on a\ntight-binding approach is described, with Ru interconnects used an example. The\nmodel allows conductivity to be computed for structures comprising large\nensembles of atoms (10^5-10^6), scales linearly with system size and can also\nincorporate defects.",
        "positive": "Imaging Electron Motion in a Few Layer MoS2 Device: Ultrathin sheets of MoS2 are a newly discovered 2D semiconductor that holds\ngreat promise for nanoelectronics. Understanding the pattern of current flow\nwill be crucial for developing devices. In this talk, we present images of\ncurrent flow in MoS2 obtained with a Scanned Probe Microscope (SPM) cooled to 4\nK. We previously used this technique to image electron trajectories in\nGaAs/AlGaAs heterostructures and graphene. The charged SPM tip is held just\nabove the sample surface, creating an image charge inside the device that\nscatters electrons. By measuring the change in resistance {\\Delta}R while the\ntip is raster scanned above the sample, an image of electron flow is obtained.\nWe present images of electron flow in an MoS2 device patterned into a hall bar\ngeometry. A three-layer MoS2 sheet is encased by two hBN layers, top and\nbottom, and patterned into a hall-bar with multilayer graphene contacts. An SPM\nimage shows the current flow pattern from the wide contact at the end of the\ndevice for a Hall density n = 1.3x10^12 cm^-2. The SPM tip tends to block flow,\nincreasing the resistance R. The pattern of flow was also imaged for a narrow\nside contact on the sample. At density n = 5.4x10^11 cm^-2; the pattern seen in\nthe SPM image is similar to the wide contact. The ability to image electron\nflow promises to be very useful for the development of ultrathin devices from\nnew 2D materials."
    },
    {
        "anchor": "The g-factors of discrete levels in nanoparticles: Spin-orbit scattering suppresses Zeeman splitting of individual energy levels\nin small metal particles. This suppression becomes significant when the\nspin-orbit scattering rate \\tau_{so}^{-1} is comparable with the quantum level\nspacing \\delta. The g-factor exhibits mesoscopic fluctuations; at small\n\\delta\\tau_{so} it is distributed according to the Maxwell distribution. At\n\\delta\\tau_{so}\\to 0 the average g-factor levels off at a small value\ng\\sim(l/L)^{1/2} given by the ratio of the electron mean free path l to the\nparticle size L. On the contrary, in 2D quantum dots the g-factor is strongly\nenhanced by spin-orbit coupling.",
        "positive": "Scattering theory on graphs (2): the Friedel sum rule: We consider the Friedel sum rule in the context of the scattering theory for\nthe Schr\\\"odinger operator $-\\Dc_x^2+V(x)$ on graphs made of one-dimensional\nwires connected to external leads. We generalize the Smith formula for graphs.\nWe give several examples of graphs where the state counting method given by the\nFriedel sum rule is not working. The reason for the failure of the Friedel sum\nrule to count the states is the existence of states localized in the graph and\nnot coupled to the leads, which occurs if the spectrum is degenerate and the\nnumber of leads too small."
    },
    {
        "anchor": "Interplay of electron-phonon nonadiabaticity and Raman scattering in the\n  wavepacket dynamics of electron-phonon-photon systems: Ultrafast wavepacket dynamics of electron-phonon-photon systems is studied by\nnumerical calculations. When nonadiabaticity of electron-phonon systems is\ntaken into account, Raman scattering process plays an important role in the\ndynamics of the system. We found that the interplay of the electron-phonon\nnonadiabaticity and the Raman scattering determines the wavepacket motion\nparticularly in the vicinity of the conical intersection of adiabatic potential\nenergy surfaces, which shows that we should consider this effect in order to\nreveal the photoexcitation/deexcitation process of materials in femtosecond\ntime scale.",
        "positive": "Spin waves in zigzag graphene nanoribbons and the stability of edge\n  ferromagnetism: We study the low energy spin excitations of zigzag graphene nanoribbons of\nvarying width. We find their energy dispersion at small wave vector to be\ndominated by antiferromagnetic correlations between the ribbon's edges, in\naccrodance with previous calculations. We point out that spin wave lifetimes\nare very long due to the semi-conducting nature of the electrically neutral\nnanoribbons. However, application of very modest gate voltages cause a\ndiscontinuous transition to a regime of finite spin wave lifetime. By further\nincreasing doping the ferromagnetic alignments along the edge become unstable\nagainst transverse spin fluctuations. This makes the experimental detection of\nferromagnetism is this class of systems very delicate, and poses a difficult\nchallenge to the possible uses of these nanoribbons as basis for spintronic\ndevices."
    },
    {
        "anchor": "Spectroscopy of cross-correlations of environmental noises with two\n  qubits: A single qubit driven by an appropriate sequence of control pulses can serve\nas a spectrometer of local noise affecting its energy splitting. We show that\nby driving and observing two spatially separated qubits, it is possible to\nreconstruct the spectrum of cross-correlations of noises acting at various\nlocations. When the qubits are driven by the same sequence of pulses, real part\nof cross-correlation spectrum can be reconstructed, while applying two distinct\nsequence to the two qubits allows for reconstruction of imaginary part of this\nspectrum. The latter quantity contains information on either causal\ncorrelations between environmental dynamics at distinct locations, or on the\noccurrence of propagation of noisy signals through the environment. We\nillustrate the former case by modeling the noise spectroscopy protocol for\nqubits coupled to correlated two-level systems. While entanglement between the\nqubits is not necessary, its presence enhances the signal from which the\nspectroscopic information is reconstructed.",
        "positive": "Frictional figures of merit for single layered nanostructures: We determined frictional figures of merit for a pair of layered honeycomb\nnanostructures, such as graphane, fluorographene, MoS$_2$ and WO$_2$ moving\nover each other, by carrying out ab-initio calculations of interlayer\ninteraction under constant loading force. Using Prandtl-Tomlinson model we\nderived critical stiffness required to avoid stick-slip behavior. We showed\nthat these layered structures have low critical stiffness even under high\nloading forces due to their charged surfaces repelling each other. The\nintrinsic stiffness of these materials exceed critical stiffness and thereby\navoid the stick-slip regime and attain nearly dissipationless continuous\nsliding. Remarkably, tungsten dioxide displays much better performance relative\nto others and heralds a potential superlubricant. The absence of mechanical\ninstabilities leading to conservative lateral forces is also confirmed directly\nby the simulations of sliding layers."
    },
    {
        "anchor": "Analytical calculation of electron's group velocity surfaces in uniform\n  strained graphene: Electron group velocity for graphene under uniform strain is obtained\nanalitically by using the Tight-Binding approx- imation. Such closed analytical\nexpressions are useful in order to calculate electronic, thermal and optical\nproperties of strained graphene. These results allow to understand the behavior\nof electrons when graphene is subjected to strong strain and nonlinear\ncorrections, for which the usual Dirac approach is not longer valid. Some\nparticular cases of uni- axial and shear strain were analized. The evolution of\nthe electron group velocity indicates a break up of the trigonal warping\nsymmetry, which is replaced by a warping consistent with the symmetry of the\nstrained reciprocal lattice. The Fermi velocity becomes strongly anisotropic,\ni.e, for a strong pure shear-strain (20% of the lattice parameter), the two\ninequivalent Dirac cones merge and the Fermi velocity is zero in one of the\nprincipal axis of deformation. We found that non-linear terms are essential to\ndescribe the effects of deformation for electrons near or at the Fermi energy.",
        "positive": "On the \"non-perturbative analysis\" of zero-temperature dephasing: I.\n  Dyson equation and self energy: We point out that the structure of the self-energy suggested in\ncond-mat/0208140 as a result of a ``non-perturbative analysis'' by ``purely\nmathematical means'' is incompatible with the very definition of the\nself-energy."
    },
    {
        "anchor": "Three-dimensional topological phase on the diamond lattice: An interacting bosonic model of Kitaev type is proposed on the\nthree-dimensional diamond lattice. Similarly to the two-dimensional Kitaev\nmodel on the honeycomb lattice which exhibits both Abelian and non-Abelian\nphases, the model has two (``weak'' and ``strong'' pairing) phases. In the weak\npairing phase, the auxiliary Majorana hopping problem is in a topological\nsuperconducting phase characterized by a non-zero winding number introduced in\nA. P. Schnyder, S. Ryu, A. Furusaki, and A. W. W. Ludwig, arXiv:0803.2786. The\ntopological character of the weak pairing phase is protected by a discrete\nsymmetry.",
        "positive": "Frequency-dependent Phonon-mediated Unidirectional Magnetoresistance in\n  a Metal on an Insulator with Highly Nonequilibrium Magnons: Heavy metal (HM)/magnet bilayers host many magnetoresistances (MR) and spin\ncaloritronic effects. Here we show that the spin Peltier effect and\nelectron-phonon scattering produce much larger unidirectional MR of an HM on a\nmagnetic insulator than existing theories that neglect the interplay between MR\nand spin caloritronic effects. By accounting for local nonequilibrium in both\nthe magnon chemical potential and temperature, our analytical model attributes\nthe observed frequency dependence of the spin Peltier MR and the spin Seebeck\neffect to the reduction of the thermal penetration depth, which approaches the\n1 micron scale magnon spin diffusion length at high frequencies."
    },
    {
        "anchor": "Exact calculation of current correlations and admittance in the\n  fractional quantum Hall regime: In this work, we focus on the finite frequency current-current correlations\nbetween edge states in a fractional quantum Hall two dimensional gas and on\ntheir relations to the quantum admittance. Using a refermionization method, we\ncalculate these quantities within the same framework. Our results apply\nwhatever the values of backscattering amplitude, frequency, voltage and\ntemperature, allowing us to reach different regimes. Auto-correlations and\ncross-correlations exhibit distinct frequency dependencies that we discuss in\ndetail.",
        "positive": "Zeeman splitting of light hole in quantum wells: comparison of theory\n  and experiments: The theory for light-hole Zeeman splitting developed in [Physica E 44, 797\n(2012)] is compared with experimental data found in literature for GaAs/AlGaAs,\nInGaAs/InP and CdTe/CdMgTe quantum wells. It is shown that the description of\nexperiments is possible with account for excitonic effects and peculiarities of\nthe hole energy spectrum in a quantum well including complex structure of the\nvalence band and the interface mixing of light and heavy holes. It is\ndemonstrated that the absolute values and the sign of the light-hole $g$-factor\nare extremely sensitive to the parametrization of the Luttinger Hamiltonian."
    },
    {
        "anchor": "Ground state phase diagram and \"parity flipping'' microwave transitions\n  in a gate-tunable Josephson Junction: We probed a gate-tunable InAs nanowire Josephson weak link by coupling it to\na microwave resonator. Tracking the resonator frequency shift when the weak\nlink is close to pinch-off, we observe that the ground state of the latter\nalternates between a singlet and a doublet when varying either the gate voltage\nor the superconducting phase difference across it. The corresponding microwave\nabsorption spectra display lines that approach zero energy close to the\nsinglet-doublet boundaries, suggesting parity flipping transitions, which are\nin principle forbidden in microwave spectroscopy and expected to arise only in\ntunnel spectroscopy. We tentatively interpret them by means of an ancillary\nstate isolated in the junction acting as a reservoir for individual electrons.",
        "positive": "Contact resistance in graphene-based devices: We report a systematic study of the contact resistance present at the\ninterface between a metal (Ti) and graphene layers of different, known\nthickness. By comparing devices fabricated on 11 graphene flakes we demonstrate\nthat the contact resistance is quantitatively the same for single-, bi-, and\ntri-layer graphene ($\\sim800 \\pm 200 \\Omega \\mu m$), and is in all cases\nindependent of gate voltage and temperature. We argue that the observed\nbehavior is due to charge transfer from the metal, causing the Fermi level in\nthe graphene region under the contacts to shift far away from the charge\nneutrality point."
    },
    {
        "anchor": "Majorana mode stacking, robustness and size effect in cylindrical\n  nanowires: We discuss the robustness of Majorana edge modes in a finite quantum nanowire\nof cylindrical shape. The nanowire is modeled as a bidimensional cylindrical\nshell of semiconductor material with proximity-induced superconductivity and an\nintrinsic Rashba spin-orbit interaction. The latter is characterized by\neffective electric and magnetic fields in transverse direction of the nanowire.\nAn applied external magnetic field pointing in an arbitrary orientation is also\nassumed. The numerical diagonalization of the Hamiltonian allows us to study\nthe spectrum of the nanowire for different experimental configurations. The\nMajorana modes prove robust against tilting of the magnetic field away from the\ncylinder longitudinal axis, if the tilt direction is perpendicular to the\neffective spin-orbit magnetic field, but fragile otherwise. On the other hand,\nwe find an increasing number of Majorana modes in the same cylinder edge for\nincreasing values of the nanowire radius. We refer to this phenomenon as\n\"stacking effect\" and it occurs due to the orthogonality between Majorana mode\nwave functions. In this manner, different Majoranas take complementary\npositions on the nanowire surface.",
        "positive": "Graphene bilayer and trilayer Moir\u00e9 lattice with Rashba spin-orbit\n  coupling: We consider twisted bilayer and trilayer graphene in the presence of Rashba\nspin-orbit coupling and explore the physics of Moir\\'e spintronics. The\nelectronic charge density has a sharp step right at the magic angles\n$\\theta_m$. As a result, local spin observables (polarization and equilibrium\nspin currents) have sharp peaks (of width about a small fraction of 1$^\\circ$)\nas a function of the twist angle $\\theta$, and abrupt sign reversals at\n$\\theta_m$. Thereby, the magic angle can be determined in an unprecedented\naccuracy. In the first chiral limit, the spin currents vanish, but the peculiar\npattern of the polarization at $\\theta_m$ persists. Major differences result in\nspintronics of twisted bilayer graphene at magic angles as compared with the\nspintronics of single and/or {\\it un-twisted} bilayer graphene. Thus, in\naddition to the numerous spectacular physical phenomena already reported in\ntwisted bilayer graphene at magic angles, new phenomena also occur in\ntwistronic spintronics."
    },
    {
        "anchor": "Classical and quantum machine learning applications in spintronics: In this article we demonstrate the applications of classical and quantum\nmachine learning in quantum transport and spintronics. With the help of a\ntwo-terminal device with magnetic impurity we show how machine learning\nalgorithms can predict the highly non-linear nature of conductance as well as\nthe non-equilibrium spin response function for any random magnetic\nconfiguration. By mapping this quantum mechanical problem onto a classification\nproblem, we are able to obtain much higher accuracy beyond the linear response\nregime compared to the prediction obtained with conventional regression\nmethods. We finally describe the applicability of quantum machine learning\nwhich has the capability to handle a significantly large configuration space.\nOur approach is applicable for solid state devices as well as for molecular\nsystems. These outcomes are crucial in predicting the behavior of large-scale\nsystems where a quantum mechanical calculation is computationally challenging\nand therefore would play a crucial role in designing nano devices.",
        "positive": "Large voltage-tunable spin valve based on a double quantum dot: We study the spin-dependent transport properties of a spin valve based on a\ndouble quantum dot. Each quantum dot is assumed to be strongly coupled to its\nown ferromagnetic lead, while the coupling between the dots is relatively weak.\nThe current flowing through the system is determined within the perturbation\ntheory in the hopping between the dots, whereas the spectrum of a quantum\ndot-ferromagnetic lead subsystem is determined by means of the numerical\nrenormalization group method. The spin-dependent charge fluctuations between\nferromagnets and quantum dots generate an effective exchange field, which\nsplits the double dot levels. Such field can be controlled, separately for each\nquantum dot, by the gate voltages or by changing the magnetic configuration of\nexternal leads. We demonstrate that the considered double quantum dot spin\nvalve setup exhibits enhanced magnetoresistive properties, including both\nnormal and inverse tunnel magnetoresistance. We also show that this system\nallows for the generation of highly spin-polarized currents, which can be\ncontrolled by purely electrical means. The considered double quantum dot with\nferromagnetic contacts can thus serve as an efficient voltage-tunable spin\nvalve characterized by high output parameters."
    },
    {
        "anchor": "Quantised Charge Transport driven by a Surface Acoustic Wave in induced\n  unipolar and bipolar junctions: Surface acoustic waves (SAWs) have been used to transport single electrons\nacross long distances of several hundreds of microns. They can potentially be\ninstrumental in the implementation of scalable quantum processors and quantum\nrepeaters, by facilitating interaction between distant qubits. While most of\nthe work thus far has focused on SAW devices in doped GaAs/AlGaAs\nheterostructures, we have developed a method of creating lateral p-n junctions\nin an undoped heterostructure containing a quantum well, with the expected\nadvantages of having reduced charge noise and increased spin-coherence\nlifetimes due to the lack of dopant scattering centres. We present experimental\nobservations of SAW-driven single-electron quantised current in an undoped\nGaAs/AlGaAs heterostructure, where single electrons were transported between\nregions of induced electrons. We also demonstrate pumping of electrons by a SAW\nacross the sub-micron depleted channel between regions of electrons and holes,\nand observe light emission at such a lateral p-n junction. Improving the\nlateral confinement in the junction should make it possible to produce a\nquantised electron-to-hole current and hence SAW-driven emission of single\nphotons.",
        "positive": "Generalized Bloch band theory for non-Hermitian bulk-boundary\n  correspondence: Bulk-boundary correspondence is the cornerstone of topological physics. In\nsome non-Hermitian topological system this fundamental relation is broken in\nthe sense that the topological number calculated for the Bloch energy band\nunder the periodic boundary condition fails to reproduce the boundary\nproperties under the open boundary. To restore the bulk-boundary correspondence\nin such non-Hermitian systems a framework beyond the Bloch band theory is\nneeded. We develop a non-Hermitian Bloch band theory based on a modified\nperiodic boundary condition that allows a proper description of the bulk of a\nnon-Hermitian topological insulator in a manner consistent with its boundary\nproperties. Taking a non-Hermitian version of the Su-Schrieffer-Heeger model as\nan example, we demonstrate our scenario, in which the concept of bulk-boundary\ncorrespondence is naturally generalized to non-Hermitian topological systems."
    },
    {
        "anchor": "Diluted chirality dependence in edge rough graphene nanoribbon\n  field-effect transistors: We investigate the role of various structural nonidealities on the\nperformance of armchair-edge graphene nanoribbon field effect transistors\n(GNRFETs). Our results show that edge roughness dilutes the chirality\ndependence often predicted by theory but absent experimentally. Instead, GNRs\nare classifiable into wide (semi-metallic) vs narrow (semiconducting) strips,\ndefining thereby the building blocks for wide-narrow-wide all-graphene devices\nand interconnects.\n  Small bandgaps limit drain bias at the expense of band-to-band tunneling in\nGNRFETs. We outline the relation between device performance metrics and\nnon-idealities such as width modulation, width dislocations and surface step,\nand non-ideality parameters such as roughness amplitude and correlation length.",
        "positive": "Tuning the exchange bias on a single atom from 1 mT to 10 T: Shrinking spintronic devices to the nanoscale ultimately requires localized\ncontrol of individual atomic magnetic moments. At these length scales, the\nexchange interaction plays important roles, such as in the stabilization of\nspin-quantization axes, the production of spin frustration, and creation of\nmagnetic ordering. Here, we demonstrate the precise control of the exchange\nbias experienced by a single atom on a surface, covering an energy range of\nfour orders of magnitude. The exchange interaction is continuously tunable from\nmilli-eV to micro-eV by adjusting the separation between a spin-1/2 atom on a\nsurface and the magnetic tip of a scanning tunneling microscope (STM). We\nseamlessly combine inelastic electron tunneling spectroscopy (IETS) and\nelectron spin resonance (ESR) to map out the different energy scales. This\ncontrol of exchange bias over a wide span of energies provides versatile\ncontrol of spin states, with applications ranging from precise tuning of\nquantum state properties, to strong exchange bias for local spin doping. In\naddition we show that a time-varying exchange interaction generates a localized\nAC magnetic field that resonantly drives the surface spin. The static and\ndynamic control of the exchange interaction at the atomic-scale provides a new\ntool to tune the quantum states of coupled-spin systems."
    },
    {
        "anchor": "Magnon bundle in a strongly dissipative magnet: Hybrid quantum systems based on magnetic platforms have witnessed the birth\nand fast development of quantum spintronics. Until now, most of the studies\nrely on magnetic excitations in low-damping magnetic insulators, particularly\nyttrium iron garnet, while a large class of magnetic systems is ruled out in\nthis interdisciplinary field. Here we propose the generation of a magnon bundle\nin a hybrid magnet-qubit system, where two or more magnons are emitted\nsimultaneously. By tuning the driving frequency of qubit to match the detuning\nbetween magnon and qubit mode, one can effectively generate a magnon bundle via\nsuper-Rabi oscillations. In contrast with general wisdom, magnetic dissipation\nplays an enabling role in generating the magnon bundle, where the relaxation\ntime of magnons determines the typical time delay between two successive\nmagnons. The maximal damping that allows an antibunched magnon bundle can reach\nthe order of 0.1, which may break the monopoly of low-dissipation magnetic\ninsulators in quantum spintronics and enables a large class of magnetic\nmaterials for quantum manipulation. Further, our finding may provide a scalable\nand generic platform to study multi-magnon physics and benefit the design of\nmagnonic networks for quantum information processing.",
        "positive": "The Dirac composite fermion of the fractional quantum Hall effect: We review the recently proposed Dirac composite fermion theory of the\nhalf-filled Landau level. This paper is based on a talk given at the Nambu\nSymposium at University of Chicago, March 11-13, 2016."
    },
    {
        "anchor": "Effect of the change in the interface structure of Pd(100)/SrTiO3 for\n  quantum-well induced ferromagnetism: Pd(100) ultrathin films show ferromagnetism induced by the confinement of\nelectrons in the film, i.e., the quantum-well mechanism. In this study, we\ninvestigate the effect of the change in the interface structure between a Pd\nfilm and SrTiO3 substrate on quantum-well induced ferromagnetism using the\nstructural phase transition of SrTiO3. During repeated measurement of\ntemperature- dependent magnetization of the Pd/SrTiO3 system, cracks were\ninduced in the Pd overlayer near the interface region by the structural phase\ntransition of SrTiO3, thereby changing the film-thickness dependence of the\nmagnetic moment. This is explained by the concept that as the magnetic moment\nin Pd(100) changed, so too did the thickness of the quantum-well. In addition,\nwe observed that the ferromagnetism in the Pd(100) disappeared with the\naccumulation of cracks due to the repetition of the temperature cycle through\nthe phase-transition temperature. This suggests that lowering the crystallinity\nof the interface structure by producing a large number of cracks has a negative\neffect on quantum-well induced ferromagnetism.",
        "positive": "Entanglement between charge qubit states and coherent states of\n  nanomechanical resonator generated by AC Josephson effect: We considered a nanoelectromechanical system consisting of a movable\nCooper-pair box qubit which is subject to an electrostatic field, and coupled\nto the two bulk superconductors via tunneling processes. We suggest that qubit\ndynamics is related to the one of a quantum oscillator and demonstrate that a\nbias voltage applied between superconductors generates states represented by\nthe entanglement of qubit states and coherent states of the oscillator if\ncertain resonant conditions are fulfilled. It is shown that a structure of this\nentanglement may be controlled by the bias voltage in a way that gives rise to\nthe entanglement incorporating so-called cat-states - the superposition of\ncoherent states. We characterize the formation and development of such states\nanalyzing the entropy of entanglement and corresponding Wigner function. The\nexperimentally feasible detection of the effect by measuring the average\ncurrent is also considered."
    },
    {
        "anchor": "Supercurrent in Nb/InAs-Nanowire/Nb Josephson junctions: We report on the fabrication and measurements of planar mesoscopic Josephson\njunctions formed by InAs nanowires coupled to superconducting Nb terminals. The\nuse of Si-doped InAs-nanowires with different bulk carrier concentrations\nallowed to tune the properties of the junctions. We have studied the junction\ncharacteristics as a function of temperature, gate voltage, and magnetic field.\nIn junctions with high doping concentrations in the nanowire Josephson\nsupercurrent values up to 100\\,nA are found. Owing to the use of Nb as\nsuperconductor the Josephson coupling persists at temperatures up to 4K. In all\njunctions the critical current monotonously decreased with the magnetic field,\nwhich can be explained by a recently developed theoretical model for the\nproximity effect in ultra-small Josephson junctions. For the low-doped\nJosephson junctions a control of the critical current by varying the gate\nvoltage has been demonstrated. We have studied conductance fluctuations in\nnanowires coupled to superconducting and normal metal terminals. The\nconductance fluctuation amplitude is found to be about 6 times larger in\nsuperconducting contacted nanowires. The enhancement of the conductance\nfluctuations is attributed to phase-coherent Andreev reflection as well as to\nthe large number of phase-coherent channels due to the large superconducting\ngap of the Nb electrodes.",
        "positive": "Electric field induced localization phenomena in a ladder network with\n  superlattice configuration: Effect of backbone environment: Electric field induced localization properties of a tight-binding ladder\nnetwork in presence of backbone sites are investigated. Based on Green's\nfunction formalism we numerically calculate two-terminal transport together\nwith density of states for different arrangements of atomic sites in the ladder\nand its backbone. Our results lead to a possibility of getting multiple\nmobility edges which essentially plays a switching action between a completely\nopaque to fully or partly conducting region upon the variation of system Fermi\nenergy, and thus, support in fabricating mesoscopic or DNA-based switching\ndevices."
    },
    {
        "anchor": "M\u00f6bius Graphene Strip as Topological Insulator: We study the electronic properties of M\\\"{o}bius graphene strip with a zigzag\nedge. We show that such graphene strip behaves as a topological insulator with\na gapped bulk and a robust metallic surface, which enjoys some features due to\nits nontrivial topology of the spatial configuration, such as the existence of\nedge states and the non-Abelian induced gauge field. We predict that the\ntopological properties of the M\\\"{o}bius graphene strip can be experimentally\ndisplayed by the destructive interference in the transmission spectrum, and the\nrobustness of edge states under certain perturbations.",
        "positive": "Suppressed magnetic circular dichroism and valley-selective\n  magneto-absorption due to the effective mass anisotropy in bismuth: We have measured the far-infrared reflectivity and Kerr angle spectra on a\nhigh-quality crystal of pure semimetallic bismuth as a function of magnetic\nfield, from which we extract the conductivity for left- and right handed\ncircular polarisations. The high spectral resolution allows us to separate the\nintraband Landau level transitions for electrons and holes. The hole transition\nexhibits 100% magnetic circular dichroism, it appears only for one polarisation\nas expected for a circular cyclotron orbit. However the dichroism for electron\ntransitions is reduced to only $13\\pm 1$%, which is quantitatively explained by\nthe large effective mass anisotropy of the electron pockets of the Fermi\nsurface. This observation is a signature of the mismatch between the metric\nexperienced by the photons and the electrons. It allows for a contactless\nmeasurement of the effective mass anisotropy and provides a direction towards\nvalley polarised magneto-optical pumping with elliptically polarised light."
    },
    {
        "anchor": "Dichotomy of saddle points in energy bands of a monolayer NbSe$_2$: We theoretically show that two distinctive spin textures manifest themselves\naround saddle points of energy bands in a monolayer NbSe$_2$ under external\ngate potentials. While the density of states at all saddle points diverge\nlogarithmically, ones at the zone boundaries display a windmill-shaped spin\ntexture while the others unidirectional spin orientations. The disparate\nspin-resolved states are demonstrated to contribute an intrinsic spin Hall\nconductivity significantly while their characteristics differ from each\nother.Based on a minimal but essential tight-binding approximation reproducing\nfirst-principles computation results, we established distinct effective Rashba\nHamiltonians for each saddle point, realizing the unique spin textures\ndepending on their momentum. Energetic positions of the saddle points in a\nsingle layer NbSe$_2$ are shown to be well controlled by a gate potential so\nthat it could be a prototypical system to test a competition between various\ncollective phenomena triggered by diverging density of states and their spin\ntextures in low-dimension.",
        "positive": "Continuous Generation of Spinmotive Force in a Patterned Ferromagnetic\n  Film: We study, both experimentally and theoretically, the generation of a dc\nspinmotive force. By exciting a ferromagnetic resonance of a comb-shaped\nferromagnetic thin film, a continuous spinmotive force is generated.\nExperimental results are well reproduced by theoretical calculations, offering\na quantitative and microscopic understanding of this spinmotive force."
    },
    {
        "anchor": "Dissipative Transport in Rough Edge Graphene Nanoribbon Tunnel\n  Transistors: We have studied quantum transport in Graphene Nanoribbon Tunnel Field-Effect\nTransistors. Unlike other studies on similar structures, we have included\ndissipative processes induced by inelastic electron-phonon scattering and edge\nroughness in the nanoribbon self-consistently within a non-equilibrium\ntransport simulation. Our results show that the dissipative scattering imposes\na limit to the minimum OFF current and a minimum subthreshold swing that can be\nobtained even for long channel lengths where direct source-drain tunneling is\ninhibited. The edge roughness, in presence of dissipative scattering, somewhat\nsurprisingly, shows a classical behavior where it mostly reduces the maximum ON\ncurrent achievable in this structure.",
        "positive": "Geometrical Defects in Josephson Junction Arrays: Dislocations and disclinations in a lattice of Josephson junctions will\naffect the dynamics of vortex excitations within the array. These defects\neffectively distort the space in which the excitations move and interact. The\ninteraction energy between such defects and excitations are determined and\nvortex trajectories in twisted lattices are calculated. Finally, possible\nexperiments observing these effects are presented."
    },
    {
        "anchor": "Magic Angle Spectroscopy: The electronic properties of heterostructures of atomically-thin van der\nWaals (vdW) crystals can be modified substantially by Moir\\'e superlattice\npotentials arising from an interlayer twist between crystals. Moir\\'e-tuning of\nthe band structure has led to the recent discovery of superconductivity and\ncorrelated insulating phases in twisted bilayer graphene (TBLG) near the\nso-called \"magic angle\" of $\\sim$1.1{\\deg}, with a phase diagram reminiscent of\nhigh T$_c$ superconductors. However, lack of detailed understanding of the\nelectronic spectrum and the atomic-scale influence of the Moir\\'e pattern has\nso far precluded a coherent theoretical understanding of the correlated states.\nHere, we directly map the atomic-scale structural and electronic properties of\nTBLG near the magic angle using scanning tunneling microscopy and spectroscopy\n(STM/STS). We observe two distinct van Hove singularities (vHs) in the LDOS\nwhich decrease in separation monotonically through 1.1{\\deg} with the bandwidth\n(t) of each vHs minimized near the magic angle. When doped near half Moir\\'e\nband filling, the conduction vHs shifts to the Fermi level and an additional\ncorrelation-induced gap splits the vHs with a maximum size of 7.5 meV. We also\nfind that three-fold (C$_3$) rotational symmetry of the LDOS is broken in doped\nTBLG with a maximum symmetry breaking observed for states near the Fermi level,\nsuggestive of nematic electronic interactions. The main features of our doping\nand angle dependent spectroscopy are captured by a tight-binding model with\non-site (U) and nearest neighbor Coulomb interactions. We find that the ratio\nU/t is of order unity, indicating that electron correlations are significant in\nmagic angle TBLG. Rather than a simple maximization of the DOS,\nsuperconductivity arises in TBLG at angles where the ratio U/t is largest,\nsuggesting a pairing mechanism based on electron-electron interactions.",
        "positive": "Inductive microwave response of Yu-Shiba-Rusinov states: We calculate the frequency-dependent admittance of a phase-biased Josephson\njunction spanning a magnetic impurity or a spinful Coulomb-blockaded quantum\ndot. The local magnetic moment gives rise to Yu-Shiba-Rusinov bound states,\nwhich govern the sub-gap absorption as well as the inductive response. We model\nthe system by a superconducting spin-polarized exchange-cotunnel junction and\ncalculate the linear current response to an AC bias voltage, including its\ndependence on phase bias as well as particle-hole, and source-drain coupling\nasymmetry. The corresponding inductive admittance is analyzed and compared to\nresults of a zero-bandwidth, as well as an infinite-gap approximation to the\nsuperconducting Anderson model. All three approaches capture the\ninteraction-induced $0-\\pi$ transition, which is reflected as a discontinuity\nin the adiabatic inductive response."
    },
    {
        "anchor": "Fluctuating spin g-tensor in small metal grains: In the presence of spin-orbit scattering, the splitting of an energy level in\na generic small metal grain due to the Zeeman coupling to a magnetic field B\ndepends on the direction of B, as a result of mesoscopic fluctuations. The\nanisotropy is described by the eigenvalues g_j^2 (j=1,2,3) of a tensor G,\ncorresponding to the (squares of) g-factors along three principal axes. We\nconsider the statistical distribution of G and find that the anisotropy is\nenhanced by eigenvalue repulsion between the g_j.",
        "positive": "Quantum Fluctuations and Dissipation in Thin Superconducting Wires: We investigate quantum fluctuations in thin superconducting wires. We\ndemonstrate that quantum phase slips dominate the system behavior at low\ntemperatures and are well in the measurable range for sufficiently thin wires.\nWe discuss the effect of dissipation, predict a new quantum\nsuperconductor-to-metal (insulator) phase transitions for wires with\nthicknesses in the 10-nm range, evaluate the resistance R(T) of such wires and\ncompare our results with recent experimental findings."
    },
    {
        "anchor": "Generating particle-like scattering states in wave transport: We introduce a procedure to generate scattering states which display\ntrajectory-like wave function patterns in wave transport through complex\nscatterers. These deterministic scattering states feature the dual property of\nbeing eigenstates to the Wigner-Smith time-delay matrix and to the transmission\nmatrix with classical (noiseless) transmission eigenvalues close to 0 or 1. Our\nprocedure to create such beam-like states is based solely on the scattering\nmatrix and successfully tested numerically for regular, chaotic and disordered\ncavities. These results pave the way for the experimental realization of highly\ncollimated wave fronts in transport through complex media with possible\napplications like secure and low-power communication.",
        "positive": "Effect of surface pinning on magnetic nanostuctures: Magnetic nanostructures are often considered as highly functional materials\nbecause they exhibit unusual magnetic properties under different external\nconditions. We study the effect of surface pinning on the core-shell magnetic\nnanostuctures of different shapes and sizes considering the spin-interaction to\nbe Ising-like. We explore the hysteresis properties and find that the exchange\nbias, even under zero field cooled conditions, increases with increase of, the\npinning density and the fraction of up-spins among the pinned ones. We explain\nthese behavior analytically by introducing a simple model of the surface. The\nasymmetry in hysteresis is found to be more prominent in a inverse core-shell\nstructure, where spin interaction in the core is antiferromagnetic and that in\nthe shell is ferromagnetic. These studied of inverse core-shell structure are\nextended to different shapes, sizes, and different spin interactions, namely\nIsing, XY- and Heisenberg models in three dimension. We also briefly discuss\nthe pinning effects on magnetic heterostructures."
    },
    {
        "anchor": "Localization at the Edge of 2D Topological Insulator by Kondo Impurities\n  with Random Anisotropies: We consider chiral electrons moving along the 1D helical edge of a 2D\ntopological insulator and interacting with a disordered chain of Kondo\nimpurities. Assuming the electron-spin couplings of random anisotropies, we map\nthis system to the problem of the pinning of the charge density wave by the\ndisordered potential. This mapping proves that arbitrary weak anisotropic\ndisorder in coupling of chiral electrons with spin impurities leads to the\nAnderson localization of the edge states.",
        "positive": "Quantum many-body theory of qubit decoherence in a finite-size spin\n  bath. II. Ensemble dynamics: Decoherence of a center spin or qubit in a spin bath is essentially\ndetermined by the many-body bath evolution. The bath dynamics can start either\nfrom a pure state or, more generally, from a statistical ensemble. In the\npreceding article [W. Yang and R. B. Liu, Phys. Rev. B \\textbf{78}, 085315\n(2008)], we have developed the cluster-correlation expansion (CCE) theory for\nthe so-called single-sample bath dynamics initiated from a factorizable pure\nstate. Here we present the ensemble CCE theory, which is based on similar ideas\nof the single-sample CCE: The bath evolution is factorized into the product of\nall possible cluster correlations, each of which accounts for the authentic\n(non-factorizable) collective excitation of a group of bath spins, and for the\nfinite-time evolution in the qubit decoherence problem, convergent results can\nbe obtained by truncating the ensemble CCE by keeping cluster correlations up\nto a certain size. A difference between the ensemble CCE and single-sample CCE\nis that the mean-field treatment in the latter formalism of the diagonal part\nof the spin-spin interaction in the bath is not possible in the former case.\nThe ensemble CCE can be applied to non-factorizable initial states. The\nensemble CCE is checked against the exact solution of an XY spin bath model.\nFor small spin baths, it is shown that single-sample dynamics is sensitive to\nthe sampling of the initial state from a thermal ensemble and hence very\ndifferent from the ensemble average."
    },
    {
        "anchor": "Theory of Transmission through disordered superlattices: We derive a theory for transmission through disordered finite superlattices\nin which the interface roughness scattering is treated by disorder averaging.\nThis procedure permits efficient calculation of the transmission thr ough\nsamples with large cross-sections. These calculations can be performed\nutilizing either the Keldysh or the Landauer-B\\\"uttiker transmission\nformalisms, both of which yield identical equations. For energies close to the\nlowest miniband, we demonstrate the accuracy of the computationally efficient\nWannier-function approximation. Our calculations indicate that the transmission\nis strongly affected by interface roughness and that information about scale\nand size of the imperfections can be obtained from transmission data.",
        "positive": "Is the magnetic field necessary for the Aharonov-Bohm effect in\n  mesoscopics?: A new class of topological mesoscopic phenomena in absence of external\nmagnetic field (meso-nucleo-spinics)is predicted, which is based on combined\naction of the nonequilibrium nuclear spin population and charge carriers\nspin-orbit interaction . As an example, we show that Aharonov-Bohm like\noscillations of the persistent current in GaAs/AlGaAs based mesoscopic rings\nmay exist, in the absence of the external magnetic field, provided that a\ntopologically nontrivial strongly nonequilibrium nuclear spin population is\ncreated. This phenomenon is due to the breaking, via the spin-orbit coupling,\nof the clock wise - anti clock wise symmetry of the charge carriers momentum,\nwhich results in the oscillatory in time persistent current."
    },
    {
        "anchor": "A protected spin-orbit induced absorption divergence in distorted Landau\n  levels: The effect of spin-orbit (and Darwin) interaction on a 2D electron gas\nsubject to a radial symmetric, inhomogeneous $1/r$-magnetic field is discussed\nanalytically in a perturbative and non-perturbative manner. For this purpose,\nwe investigate the radial Hall conductivity that emerges from an additional\nhomogeneous electric field perturbation perpendicular to the 2D electron gas,\nwhich solely interacts via spin-orbit coupling. Numerical calculations of the\nabsorptive spin-orbit spectra show for an ideal InSb electron gas a behaviour\nthat is dominated by the localized (atomic) part of the distorted Landau\nlevels. In contrast, however, we also find analytically that a (non-local)\ndivergent static response emerges for Fermi energies close to the ionization\nenergy in the thermodynamic limit. The divergent linear response implies that\nthe external electric field is entirely absorbed outside the 2D electron gas by\ninduced radial spin-orbit currents, as it would be the case inside a perfect\nconductor. This spin-orbit induced polarization mechanism depends on the\neffective $g^*$-factor of the material for which it shows a critical behaviour\nat $g^*_c=2$, where it abruptly switches direction. The diverging absorption\nrelies on the presence of degenerate energies with allowed selection rules that\nare imposed by the radial symmetry of our inhomogeneous setup. We show\nanalytically the presence of a discrete Rydberg-like band structure that obeys\nthese symmetry properties. In a last step, we investigate the robustness of the\nspectra by solving analytically the Dirac equation expanded up to order\n$1/(mc)^2$. We find that the distorted Landau-levels, and thus the divergent\nspin-orbit polarization, remain protected with respect to slow changes of the\napplied $1/r$-magnetic field.",
        "positive": "Curvature of gap closing features and the extraction of Majorana\n  nanowire parameters: Recent tunneling conductance measurements of Majorana nanowires show a strong\nvariation in the magnetic field dependence of the superconducting gap among\ndifferent devices. Here, we theoretically study the magnetic field dependence\nof the gap closing feature and establish that the degree of convexity (or\nconcavity) of the gap closing as a function of Zeeman field can provide\ncritical constraints on the underlying microscopic parameters of the\nsemiconductor-superconductor hybrid system model. Specifically, we show that\nthe gap closing feature is entirely concave only for strong spin-orbit coupling\nstrength relative to the chemical potential. Additionally, the non-linearity\n(i.e. concavity or convexity) of the gap closing as a function of magnetic\nfield complicates the simple assignment of a constant effective $ g $-factor to\nthe states in the Majorana nanowire. We develop a procedure to estimate the\neffective $ g $-factor from recent experimental data that accounts for the\nnon-linear gap closing resulting from the interplay between chemical potential\nand spin-orbit coupling. Thus, measurements of the magnetic field dependence of\nthe gap closure on the trivial side of the topological quantum phase transition\ncan provide useful information on parameters that are critical to the\ntheoretical modeling of Majorana nanowires."
    },
    {
        "anchor": "Light-induced valley currents and magnetization in graphene rings: We study the non-equilibrium dynamics in a mesoscopic graphene ring excited\nby picoseconds shaped electromagnetic pulses. We predict an ultrafast buildup\nof charge polarization, currents and orbital magnetization. Applying the light\npulses identified here, non-equilibrium valley currents are generated in a\ngraphene ring threaded by a stationary magnetic flux. We predict a finite\ngraphene ring magnetization even for a vanishing charge current; the\nmagnetization emerges due to the light-induced difference of the valley\npopulations.",
        "positive": "Two-subband system in quantizing magnetic field: Probing many-body gap\n  by non-equilibrium phonons: We study the many-body effects in a two-subband quasi-two-dimensional\nelectron system in a quantizing magnetic field at filling factor three. A\nmanifestation of these effects in the phonon absorption spectroscopy is\ndiscussed. The electron system is mapped onto a two-level system with the\nseparation between levels determined by the intersubband splitting and the\ncyclotron energy. The electron-electron interaction enhances the excitation\ngap, which exists at all values of the interlevel splitting. This results in a\nsingle-peak structure of the phonon absorption rate as a function of magnetic\nfield, instead of the double-peak structure for non-interacting electrons."
    },
    {
        "anchor": "Unified Topological Response Theory for Gapped and Gapless Free Fermions: We derive a scheme for systematically enumerating the responses of gapped as\nwell as gapless systems of free fermions to electromagnetic and strain fields\nstarting from a common parent theory. Using the fact that position operators in\nthe lowest Landau level of a quantum Hall state are canonically conjugate, we\nconsider a massive Dirac fermion in $2n$ spatial dimensions under $n$ mutually\northogonal magnetic fields and reinterpret physical space in the resulting\nzeroth Landau level as phase space in $n$ spatial dimensions. The bulk\ntopological responses of the parent Dirac fermion, given by a Chern-Simons\ntheory, translate into quantized insulator responses, while its edge anomalies\ncharacterize the response of gapless systems. Moreover, various physically\ndifferent responses are seen to be related by the interchange of position and\nmomentum variables. We derive many well-known responses, and demonstrate the\nutility of our theory by predicting spectral flow along dislocations in Weyl\nsemimetals.",
        "positive": "Tailoring Magnetic Anisotropy in Cr$_2$Ge$_2$Te$_6$ by Electrostatic\n  Gating: Electrical control of magnetism of a ferromagnetic semiconductor offers\nexciting prospects for future spintronic devices for processing and storing\ninformation. Here, we report observation of electrically modulated magnetic\nphase transition and magnetic anisotropy in thin crystal of Cr$_2$Ge$_2$Te$_6$\n(CGT), a layered ferromagnetic semiconductor. We show that heavily\nelectron-doped ($\\sim$ $10^{14}$ cm$^{-2}$) CGT in an electric double-layer\ntransistor device is found to exhibit hysteresis in magnetoresistance (MR), a\nclear signature of ferromagnetism, at temperatures up to above 200 K, which is\nsignificantly higher than the known Curie temperature of 61 K for an undoped\nmaterial. Additionally, angle-dependent MR measurements reveal that the\nmagnetic easy axis of this new ground state lies within the layer plane in\nstark contrast to the case of undoped CGT, whose easy axis points in the\nout-of-plane direction. We propose that significant doping promotes\ndouble-exchange mechanism mediated by free carriers, prevailing over the\nsuperexchange mechanism in the insulating state. Our findings highlight that\nelectrostatic gating of this class of materials allows not only charge flow\nswitching but also magnetic phase switching, evidencing their potential for\nspintronics applications."
    },
    {
        "anchor": "Broad frequency and amplitude control of vibration in freestanding\n  graphene via scanning tunneling microscopy with calculated dynamic\n  pseudo-magnetic fields: A technique to locally generate mechanical vibrations in freestanding\ngraphene using scanning tunneling microscopy (STM) is presented. The frequency\nof the mechanical vibrations is tuned over nearly four decades and is centered\naround 10 Hz. The amplitude of the vibrations also changes over nearly three\ndecades centered on 1 nm. The oscillating motion is generated in two ways:\nfirst, by scanning the STM tip on the surface and second, by scanning the bias\nvoltage on the STM tip. The frequency and amplitude of the displaced\nfreestanding graphene is quantitatively transformed to the frequency and\nstrength of the locally generated pseudo-magnetic field for our specific\ngeometry.",
        "positive": "Dynamics of nuclear spin polarization induced and detected by coherently\n  precessing electron spins in fluorine-doped ZnSe: We study the dynamics of optically-induced nuclear spin polarization in a\nfluorine-doped ZnSe epilayer via time-resolved Kerr rotation. The nuclear\npolarization in the vicinity of a fluorine donor is induced by interaction with\ncoherently precessing electron spins in a magnetic field applied in the Voigt\ngeometry. It is detected by nuclei-induced changes in the electron spin\ncoherence signal. This all-optical technique allows us to measure the\nlongitudinal spin relaxation time $T_{1}$ of the $^{77}\\text{Se}$ isotope in a\nmagnetic field range from 10 to 130~mT under illumination. We combine the\noptical technique with radio frequency methods to address the coherent spin\ndynamics of the nuclei and measure Rabi oscillations, Ramsey fringes and the\nnuclear spin echo. The inhomogeneous spin dephasing time $T_{2}^{*}$ and the\nspin coherence time $T_{2}$ of the $^{77}\\text{Se}$ isotope are measured. While\nthe $T_{1}$ time is on the order of several milliseconds, the $T_{2}$ time is\nseveral hundred microseconds. The experimentally determined condition $T_{1}\\gg\nT_{2}$ verifies the validity of the classical model of nuclear spin cooling for\ndescribing the optically-induced nuclear spin polarization."
    },
    {
        "anchor": "Rayleigh waves, surface disorder, and phonon localization in\n  nanostructures: We introduce a technique to calculate thermal conductivity in disordered\nnanostructures: a finite-difference time-domain (FDTD) solution of the elastic\nwave equation combined with the Green-Kubo formula. The technique captures\nphonon wave behavior and scales well to nanostructures that are too large or\ntoo surface disordered to simulate with many other techniques. We investigate\nthe role of Rayleigh waves and surface disorder on thermal transport by\nstudying graphenelike nanoribbons with free edges (allowing Rayleigh waves) and\nfixed edges (prohibiting Rayleigh waves). We find that free edges result in a\nsignificantly lower thermal conductivity than fixed ones. Free edges both\nintroduce Rayleigh waves and cause all low-frequency modes (bulk and surface)\nto become more localized. Increasing surface disorder on free edges draws\nenergy away from the center of the ribbon and toward the disordered edges,\nwhere it gets trapped in localized surface modes. These effects are not seen in\nribbons with fixed boundary conditions and illustrate the importance of phonon\nsurface modes in nanostructures.",
        "positive": "Direct Observation of the Skyrmion Hall Effect: The well-known Hall effect describes the transverse deflection of charged\nparticles (electrons or holes) in an electric-current carrying conductor under\nthe influence of perpendicular magnetic fields, as a result of the Lorentz\nforce. Similarly, it is intriguing to examine if quasi-particles without an\nelectric charge, but with a topological charge, show related transverse motion.\nChiral magnetic skyrmions with a well-defined spin topology resulting in a unit\ntopological charge serve as good candidates to test this hypothesis. In spite\nof the recent progress made on investigating magnetic skyrmions, direct\nobservation of the skyrmion Hall effect in real space has, remained elusive.\nHere, by using a current-induced spin Hall spin torque, we experimentally\nobserve the skyrmion Hall effect by driving skyrmions from creep motion into\nthe steady flow motion regime. We observe a Hall angle for the magnetic\nskyrmion motion as large as 15 degree for current densities smaller than 10\nMA/cm^(2) at room temperature. The experimental observation of transverse\ntransport of skyrmions due to topological charge may potentially create many\nexciting opportunities for the emerging field of skyrmionics, including novel\napplications such as topological selection."
    },
    {
        "anchor": "Extracting inter-dot tunnel couplings between few donor quantum dots in\n  silicon: The long term scaling prospects for solid-state quantum computing\narchitectures relies heavily on the ability to simply and reliably measure and\ncontrol the coherent electron interaction strength, known as the tunnel\ncoupling, $t_c$. Here, we describe a method to extract the $t_c$ between two\nquantum dots (QDs) utilising their different tunnel rates to a reservoir. We\ndemonstrate the technique on a few donor triple QD tunnel coupled to a nearby\nsingle-electron transistor (SET) in silicon. The device was patterned using\nscanning tunneling microscopy-hydrogen lithography allowing for a direct\nmeasurement of the tunnel coupling for a given inter-dot distance. We extract\n${t}_{{\\rm{c}}}=5.5\\pm 1.8\\;{\\rm{GHz}}$ and ${t}_{{\\rm{c}}}=2.2\\pm\n1.3\\;{\\rm{GHz}}$ between each of the nearest-neighbour QDs which are separated\nby 14.5 nm and 14.0 nm, respectively. The technique allows for an accurate\nmeasurement of $t_c$ for nanoscale devices even when it is smaller than the\nelectron temperature and is an ideal characterisation tool for multi-dot\nsystems with a charge sensor.",
        "positive": "Topological gap states of semiconducting armchair graphene ribbons: In semiconducting armchair graphene ribbons a chiral lattice deformation can\ninduce pairs of topological gap states with opposite energies. Near the\ncritical value of the deformation potential these kink and antikink states\nbecome almost degenerate with zero energy and have a fractional charge\none-half. Such a semiconducting armchair ribbon represents a one-dimensional\ntopological insulator with nearly zero energy end states. Using data collapse\nof numerical results we find that the shape of the kink displays an anomalous\npower-law dependence on the width of the local lattice deformation. We suggest\nthat these gap states may be probed in optical measurements. However,\n\"metallic\" armchair graphene ribbons with a gap induced by many-electron\ninteractions have no gap states and are not topological insulators."
    },
    {
        "anchor": "Magnetophonon resonance in graphite: High-field Raman measurements and\n  electron-phonon coupling contributions: We perform Raman scattering experiments on natural graphite in magnetic\nfields up to 45 T, observing a series of peaks due to interband electronic\nexcitations over a much broader magnetic field range than previously reported.\nWe also explore electron-phonon coupling in graphite via magnetophonon\nresonances. The Raman G peak shifts and splits as a function of magnetic field,\ndue to the magnetically tuned coupling of the E2g optical phonons with the K-\nand H-point inter-Landau-level excitations. The analysis of the observed\nanticrossing behavior allows us to determine the electron-phonon coupling for\nboth K- and H-point carriers. In the highest field range (>35 T) the G peak\nnarrows due to suppression of electron-phonon interaction.",
        "positive": "Finite Layer Thickness Stabilizes the Pfaffian State for the 5/2\n  Fractional Quantum Hall Effect: Wavefunction Overlap and Topological\n  Degeneracy: We find the finite-width, i.e., the layer thickness, of experimental\nquasi-two dimensional systems produces a physical environment sufficient to\nstabilize the Moore-Read Pfaffian state thought to describe the fractional\nquantum Hall effect at filling factor $\\nu=5/2$. This conclusion is based on\nexact calculations performed in the spherical and torus geometries, studying\nwavefunction overlap and ground state degeneracy"
    },
    {
        "anchor": "Unveiling valley lifetimes of free charge carriers in monolayer WSe$_2$: We report on nanosecond long, gate-dependent valley lifetimes of free charge\ncarriers in monolayer WSe$_2$, unambiguously identified by the combination of\ntime-resolved Kerr rotation and electrical transport measurements. While the\nvalley polarization increases when tuning the Fermi level into the conduction\nor valence band, there is a strong decrease of the respective valley lifetime\nconsistent with both electron-phonon and spin-orbit scattering. The longest\nlifetimes are seen for spin-polarized bound excitons in the band gap region. We\nexplain our findings via two distinct, Fermi level-dependent scattering\nchannels of optically excited, valley polarized bright trions either via dark\nor bound states. By electrostatic gating we demonstrate that the transition\nmetal dichalcogenide WSe$_2$ can be tuned to be either an ideal host for\nlong-lived localized spin states or allow for nanosecond valley lifetimes of\nfree charge carriers (> 10 ns).",
        "positive": "Photonic thermal conduction by infrared plasmonic resonators in\n  semiconductor nanowires: Photons typically do not contribute to thermal transport within a solid due\nto their low energy density and tendency to be quickly absorbed. We propose a\npractical material system - infrared plasmonic resonators embedded in a\nsemiconductor nanowire - that leverages near-field electromagnetic coupling to\nachieve photonic thermal transport comparable to the electronic and phononic\ncontributions. We analytically show photonic thermal conductivities up to about\n1 W m-1 K-1 for 10 nm diameter Si and InAs nanowires containing repeated\nresonators at 500 K. The nanowire system outperforms plasmonic particles in\nisotropic environments and presents a pathway for photonic thermal transport to\nexceed that of phonons and electrons."
    },
    {
        "anchor": "Conductance of a hydrogen molecule: Recently Smit et al. [Nature 419, 906 (2002)] have reported that a single\nhydrogen molecule can form a bridge between Pt electrodes, which has a\nconductance close to one quantum unit, carried by a single channel. We present\ndensity functional calculations explaining these experimental findings. We show\nthat the symmetry of the molecular orbitals selects a single conduction\nchannel. The transmission of this channel is close to unity due to a\ncombination of the charge transfer between hydrogen and the Pt contacts and the\nstrong hybridization between the bonding state of the molecule and the d-band\nof the Pt leads.",
        "positive": "Hysteretic resistance spikes in quantum Hall ferromagnets without\n  domains: We use spin-density-functional theory to study recently reported hysteretic\nmagnetoresistance \\rho_{xx} spikes in Mn-based 2D electron gases\n[Jaroszy\\'{n}ski et al. Phys. Rev. Lett. (2002)]. We find hysteresis loops in\nour calculated Landau fan diagrams and total energies signaling\nquantum-Hall-ferromagnet phase transitions. Spin-dependent exchange-correlation\neffects are crucial to stabilize the relevant magnetic phases arising from\ndistinct symmetry-broken excited- and ground-state solutions of the Kohn-Sham\nequations. Besides hysteretic spikes in \\rho_{xx}, we predict hysteretic dips\nin the Hall resistance \\rho_{xy}. Our theory, without domain walls,\nsatisfactorily explains the recent data."
    },
    {
        "anchor": "Optimizing the interfacial thermal conductance at gold-alkane junctions\n  from 'First Principles': We theoretically explore the influence of end-group chemistry (bond stiffness\nand mass) on the interfacial thermal conductance at a gold-alkane interface. We\naccomplish this using the Non-Equilibrium Green's Function (NEGF) coupled with\nfirst principle parameters in Density Functional Theory (DFT) within the\nharmonic approximation. Our results indicate that the interfacial thermal\nconductance is not a monotonic function of either chemical parameters, but\ninstead maximizes at an optimal set of mass and bonding strength. This maximum\nis a result of the interplay between the overlap in local density of states of\nthe device and that in the contacts, as well as the phonon group velocity. We\nalso demonstrate the intrinsic relationship between the Diffusive Mismatch\nModel (DMM) and the properties from NEGF, and provide an approach to get DMM\nfrom first principles NEGF. By comparing the NEGF based DMM conductance and\nrange of conductance while altering the mass and bonding strength, we show that\nDMM provides an upper bound for elastic transport in this dimensionally\nmismatched system. We thus have a prescription to enhance the thermal\nconductance of systems at low temperatures or at low dimensions where inelastic\nscattering is considerably suppressed.",
        "positive": "Phase transition from a composite fermion liquid to a Wigner solid in\n  the lowest Landau level of ZnO: Interactions between the constituents of a condensed matter system can drive\nit through a plethora of different phases due to many-body effects. A prominent\nplatform for this type of behavior is a two-dimensional electron system in a\nmagnetic field, which evolves intricately through various gaseous, liquid and\nsolids phases governed by Coulomb interaction. Here we report on the\nexperimental observation of a phase transition between the Laughlin liquid of\ncomposite fermions and the adjacent insulating phase of a magnetic\nfield-induced Wigner solid. The experiments are performed in the lowest Landau\nlevel of a MgZnO/ZnO two-dimensional electron system with attributes of both a\nliquid and a solid. An in-plane magnetic field component applied on top of the\nperpendicular magnetic field extends the Wigner phase further into the liquid\nphase region. Our observations indicate the direct competition between a Wigner\nsolid and a Laughlin liquid both formed by composite particles rather than bare\nelectrons."
    },
    {
        "anchor": "Impact of the interfacial Dzyaloshinskii-Moriya interaction on the band\n  structure of one-dimensional artificial magnonic crystals: a micromagnetic\n  study: We present the results of a systematic micromagnetic study of the effect of\nthe Dzyaloshinskii-Moriya interaction (DMI) on the spin wave band structure of\ntwo one-dimensional magnonic crystals (MCs), both with the same periodicity\np=300 nm, but different implementation of the DMI modulation. In the first\nsystem the artificial periodicity was achieved by modulating the interfacial\nDMI constant D, while in the second system also the sample morphology was\nmodulated. Due to the folding property of the band structure in the dispersion\nrelations of the magnonic crystals it is possible to extend the sensitivity of\nBrillouin light scattering towards weak DMI strength (D in the range from 0 to\n0.5 mJ/m2), by measuring the frequency splitting of folded modes in high-order\nartificial Brillouin zones, since the splitting increases almost linearly with\nthe band index. For relatively large values of the DMI (D in the range from 1.0\nto 2.0 mJ/m2) the spin waves dispersion relations present flat modes for\npositive wavevectors, separated by forbidden frequency gaps whose amplitude\ndepend on the value of D. These frequency gaps are more pronounced for the\nsample with morphology modulation. The non-reciprocal, localised, spatial\nprofiles of these modes in both MCs are discussed with reference to spin waves\nin plain films and in isolated stripes of the same thickness.",
        "positive": "Effective Field Theory of Interacting \u03c0-Electrons: We develop a \\pi-electron effective field theory (\\pi-EFT) wherein the\ntwo-body Hamiltonian for a \\pi-electron system is expressed in terms of three\neffective parameters: the \\pi-orbital quadrupole moment, the on-site repulsion,\nand a dielectric constant. As a first application of this \\pi-EFT, we develop a\nmodel of screening in molecular junctions based on image multipole moments, and\nuse this to investigate the reduction of the HOMO-LUMO gap of benzene. Beyond\nthis, we also use \\pi-EFT to calculate the differential conductance spectrum of\nthe prototypical benzenedithiol-Au single-molecule junction and the\n\\pi-electron contribution to the van der Waals interaction between benzene and\na metallic electrode."
    },
    {
        "anchor": "Conductance fluctuation and shot noise in disordered graphene systems, a\n  perturbation expansion approach: We report the investigation of conductance fluctuation and shot noise in\ndisordered graphene systems with two kinds of disorder, Anderson type\nimpurities and random dopants. To avoid the brute-force calculation which is\ntime consuming and impractical at low doping concentration, we develop an\nexpansion method based on the coherent potential approximation (CPA) to\ncalculate the average of four Green's functions and the results are obtained by\ntruncating the expansion up to 6th order in terms of \"single-site-T-matrix\".\nSince our expansion is with respect to \"single-site-T-matrix\" instead of\ndisorder strength $W$, good result can be obtained at 6th order for finite $W$.\nWe benchmark our results against brute-force method on disordered graphene\nsystems as well as the two dimensional square lattice model systems for both\nAnderson disorder and the random doping. The results show that in the regime\nwhere the disorder strength $W$ is small or the doping concentration is low,\nour results agree well with the results obtained from the brute-force method.\nSpecifically, for the graphene system with Anderson impurities, our results for\nconductance fluctuation show good agreement for $W$ up to $0.4t$, where $t$ is\nthe hopping energy. While for average shot noise, the results are good for $W$\nup to $0.2t$. When the graphene system is doped with low concentration 1%, the\nconductance fluctuation and shot noise agrees with brute-force results for\nlarge $W$ which is comparable to the hopping energy $t$. At large doping\nconcentration 10%, good agreement can be reached for conductance fluctuation\nand shot noise for $W$ up to $0.4t$. We have also tested our formalism on\nsquare lattice with similar results. Our formalism can be easily combined with\nlinear muffin-tin orbital first-principles transport calculations for light\ndoping nano-scaled systems, making prediction on variability of nano-devices.",
        "positive": "How to detect a genuine quantum pump effect in graphene?: Quantum pumping in graphene has been predicted in recent years. Till date\nthere have been no experiments indicating a graphene based quantum pump. This\nis not uncommon as in case of other non-Dirac behavior showing materials it has\nnot yet been unambiguously experimentally detected. The reason being that in\nexperiments with such materials the rectification effect overshadows the pumped\ncurrent. In this work we answer the question posed in the title by taking\nrecourse to \"strain\". We show that the symmetries of the rectified and pumped\ncurrents towards strain reversal can effectively distinguish between the two."
    },
    {
        "anchor": "From fractional boundary charges to quantized Hall conductance: We study the fractional boundary charges (FBCs) occurring in nanowires in the\npresence of periodically modulated chemical potentials and connect them to the\nFBCs occurring in a two-dimensional electron gas in the presence of a\nperpendicular magnetic field in the integer quantum Hall effect (QHE) regime.\nFirst, we show that in nanowires the FBCs take fractional values and change\nlinearly as a function of phase offset of the modulated chemical potential.\nThis linear slope takes quantized values determined by the period of the\nmodulation and depends only on the number of the filled bands. Next, we\nestablish a mapping from the one-dimensional system to the QHE setup, where we\nagain focus on the properties of the FBCs. By considering a cylinder topology\nwith an external flux similar to the Laughlin construction, we find that the\nslope of the FBCs as function of flux is linear and assumes universal quantized\nvalues, also in the presence of arbitrary disorder. We establish that the\nquantized slopes give rise to the quantization of the Hall conductance.\nImportantly, the approach via FBCs is valid for arbitrary flux values and\ndisorder. The slope of the FBCs plays the role of a topological invariant for\nclean and disordered QHE systems. Our predictions for the FBCs can be tested\nexperimentally in nanowires and in Corbino disk geometries in the integer QHE\nregime.",
        "positive": "Positive noise cross-correlations in superconducting hybrids: Roles of\n  interfaces and interactions: Shot noise cross-correlations in normal metal-superconductor-normal metal\nstructures are discussed at arbitrary interface transparencies using both the\nscattering approach of Blonder, Tinkham and Klapwik and a microscopic Green's\nfunction approach. Surprisingly, negative crossed conductance in such set-ups\n[R. Melin and D. Feinberg, Phys. Rev. B 70, 174509 (2004)] does not preclude\nthe possibility of positive noise cross-correlations for almost transparent\ncontacts. We conclude with a phenomenological discussion of interactions in the\none dimensional leads connected to the superconductor, which induce sign\nchanges in the noise cross-correlations."
    },
    {
        "anchor": "Dirac Green's function approach to graphene-superconductor junctions\n  with well defined edges: This work presents a novel approach to describe spectral properties of\ngraphene layers with well defined edges. We microscopically analyze the\nboundary problem for the continuous Bogoliubov-de Gennes-Dirac (BdGD) equations\nand derive the Green functions for normal and superconducting graphene layers.\nImporting the idea used in tight-binding (TB) models of a microscopic hopping\nthat couples different regions, we are able to set up and solve an algebraic\nDyson's equation describing a graphene-superconductor junction. For this\ncoupled system we analytically derive the Green functions and use them to\ncalculate the local density of states and the spatial variation of the induced\npairing correlations in the normal region. Signatures of specular Andreev\nreflections are identified.",
        "positive": "On-chip all-electrical determination of the magnetoelastic coupling\n  constant of magnetic heterostructures: We have developed an approach to determine the magnetoelastic coupling\nconstant of magnetic layers in thin film heterostructures. The film is formed\non a piezoelectric substrate between two interdigital transducers (IDT), a\nplatform often used to construct a surface acoustic wave device. With the\nsubstrate piezoelectricity, strain is induced into the film by applying a dc\nvoltage to the IDTs. The strain causes changes in the magnetization direction\nof the magnetic layer, which is probed by measuring changes, if any, in the\ntransverse resistance of the heterostructure. We find the extracted\nmagnetoelastic coupling constant of the magnetic layer (CoFeB) depends on the\nfilm stacking. Such change can be accounted for provided that the elastic\nproperties of the layers that constitute the heterostructures are taken into\naccount. The on-chip all-electrical approach described here provides a\nversatile means to quantitatively assess the magnetoelastic coupling constant\nof thin film heterostructures."
    },
    {
        "anchor": "Valley polarization and susceptibility of composite fermions around\n  nu=3/2: We report magnetotransport measurements of fractional quantum Hall states in\nan AlAs quantum well around Landau level filling factor nu = 3/2, demonstrating\nthat the quasiparticles are composite Fermions (CFs) with a valley degree of\nfreedom. By monitoring the valley level crossings for these states as a\nfunction of applied symmetry-breaking strain, we determine the CF valley\nsusceptibility and polarization. The data can be explained well by a simple\nLandau level fan diagram for CFs, and are in nearly quantitative agreement with\nthe results reported for CF spin polarization.",
        "positive": "Optically-controlled logic gates for two spin qubits in\n  vertically-coupled quantum dots: We describe an interaction mechanism between electron spins in a\nvertically-stacked double quantum dot that can be used for controlled two-qubit\noperations. This interaction is mediated by excitons confined within, and\ndelocalized over, the double dot. We show that gates equivalent to the\nSQRT-SWAP gate can be obtained in times much less than the exciton relaxation\ntime and that the negative effects of hole-mixing and spontaneous emission do\nnot seriously affect these results."
    },
    {
        "anchor": "Effect of Temperature and Doping on Plasmon Excitations for an\n  Encapsulated Double-Layer Graphene Heterostructure: We perform a comprehensive analysis of the spectrum of graphene plasmons\nwhich arise when a pair of sheets are confined between conducting materials.\nThe associated enhanced local fields may be employed in the manipulation of\nlight on the nanoscale by adjusting the separation between the graphene layers,\nthe energy band gap as well as the concentration of charge carriers in the\nconducting media surrounding the two-dimensional (2D) layers. We present a\ntheoretical formalism, based on the calculation of the surface response\nfunction, for determining the plasmon spectrum of an encapsulated pair of 2D\nlayers and apply it to graphene. We solve the coupled equations involving the\ncontinuity of the electric potential and discontinuity of the electric field at\nthe interfaces separating the constituents of the hybrid structure. We have\ncompared the plasmon modes for encapsulated gapped and gapless graphene. The\nassociated nonlocal graphene plasmon spectrum coupled to the \"sandwich\" system\nshow a linear acoustic plasmon mode as well as a low-frequency mode\ncorresponding to in-phase oscillations of the adjacent 2D charge densities.\nThese calculations are relevant to the study of energy transfer via plasmon\nexcitations when graphene is confined by a pair of thick conducting materials.",
        "positive": "Exchange interaction and tunneling induced transparency in coupled\n  quantum dots: We investigate the optical response of quantum dot molecules coherently\ndriven by polarized laser light. Our description includes the splitting in\nexcitonic levels caused by isotropic and anisotropic exchange interactions. We\nconsider interdot transitions mediated by hole tunneling between states with\nthe same total angular momentum and between bright and dark exciton states, as\nallowed by spin-flip hopping between the dots in the molecule. Using realistic\nexperimental parameters we demonstrate that the excitonic states coupled by\ntunneling exhibit a rich and controllable optical response. We show that\nthrough the appropriate control of an external electric field and light\npolarization, the tunneling coupling establishes an efficient destructive\nquantum interference path that creates a transparency window in the absorption\nspectra, whenever states of appropriate symmetry are mixed by the carrier\ntunneling. We explore the relevant parameter space that allows probing this\nphenomenon in experiments. Controlled variation of applied field and laser\ndetuning would allow the optical characterization of spin-preserving and\nspin-flip hopping amplitudes in such systems, by measuring the width of the\ntunneling-induced transparency windows."
    },
    {
        "anchor": "Single-Molecule Magnets: High-Field Electron Paramagnetic Resonance\n  Evaluation of the Single-Ion Zero-Field Interaction in a Zn3Ni Complex: High-field electron paramagnetic resonance (HFEPR) spectra were collected at\nseveral frequencies for single crystal [Zn3.91Ni0.09(hmp)4(dmb)4Cl4] (1), where\ndmb is 3,3-dimethyl-1-butanol and hmp is the monoanion of\n2-hydroxymethylpyridine. This crystal is isostructural to [Ni4(hmp)4(dmb)4Cl4]\n(2), which has been characterized to be a single-molecule magnet (SMM) with\nfast quantum tunneling of its magnetization (QTM). The single NiII ion\nzero-field-splitting (zfs) parameters D [= -5.30(5) cm-1] and E [= +/-1.20(2)\ncm-1] in the doped complex 1 were evaluated by rotation of a crystal in three\nplanes. The easy-axes of magnetization associated with the single-ion zfs\ninteractions were also found to be tilted 15 degrees away from the\ncrystallographic c-direction. This inclination provides a possible explanation\nfor the fast QTM observed for complex 2. The single-ion zfs parameters are then\nrelated to the zfs parameters for the Ni4 molecule by irreducible tensor\nmethods to give D = -0.69 cm-1 for the S = 4 ground state of the SMM, where the\naxial zfs interaction is given by DSz2.",
        "positive": "Quantum-oscillation-modulated angular dependences of the positive\n  longitudinal magnetoconductivity and planar Hall effect in Weyl semimetals: We study the positive longitudinal magnetoconductivity (LMC) and planar Hall\neffect as emergent effects of the chiral anomaly in Weyl semimetals, following\na recent-developed theory by integrating the Landau quantization with Boltzmann\nequation. It is found that, in the weak magnetic field regime, the LMC and\nplanar Hall conductivity (PHC) obey $\\cos^{6}\\theta$ and $\\cos^{5}\\theta\\sin\n\\theta$ dependences on the angle $\\theta$ between the magnetic and electric\nfields. For higher magnetic fields, the LMC and PHC cross over to\n$\\cos^{2}\\theta$ and $\\cos\\theta\\sin\\theta$ dependences, respectively.\nInterestingly, the PHC could exhibit quantum oscillations with varying\n$\\theta$, due to the periodic-in-$1/B$ oscillations of the chiral chemical\npotential. When the magnetic and electric fields are noncollinear, the LMC and\nPHC will deviate from the classical $B$-quadratic dependence, even in the weak\nmagnetic field regime."
    },
    {
        "anchor": "Influence of chopped laser light onto the electronic transport through\n  atomic-sized contacts: This article reports on the influence of laser irradiation onto the\nelectrical conductance of gold nanocontacts established with the mechanically\ncontrollable breakjunction technique (MCB). We concentrate here on the study of\nreversible conductance changes which can be as high as 200%. We investigate the\ndependence on the initial conductance of the contacts, the wavelength, the\nintensity and position of the laser spot with respect to the sample. Under most\nconditions an enhancement of the conductance is observed. We discuss several\nphysical mechanisms which might contribute to the observed effect including\nthermal expansion, rectification and photon-assisted transport. We conclude\nthat thermal expansion is not the dominating one.",
        "positive": "Percolative Charge Transport In Binary Nanocrystal Solids: We simulated electron transport across a binary nanocrystal solid (BNS) of\nPbSe NCs with diameters of 6.5nm and 5.1nm. We used our Hierarchical\nNanoparticle Transport Simulator HINTS to model the transport in these BNSs.\nThe mobility exhibits a minimum at a Large-NC-fraction f_LNC=0.25. The mobility\nminimum is deep at T=80K and partially smoothed at T=300K. We explain this\nminimum as follows. As the LNC fraction f_LNC starts growing from zero, the few\nLNCs act as traps for the electrons traversing the BNS because their relevant\nenergy level is lower. Therefore, increasing the f_LNC concentration of these\ntraps decreases the mobility. As increasing f_LNC reaches the percolation\nthreshold f_LNC=f_p, the LNCs form sample-spanning networks that enable\nelectrons to traverse the entire BNS via these percolating LNC networks.\nTransport through the growing percolating LNC networks drives the rapid growth\nof the mobility as f_LNC grows past f_p. Therefore, the electron mobility\nexhibits a pronounced minimum as a function of f_LNC, centered at f_LNC=f_p.\nThe position of the mobility minimum shifts to larger LNC fractions as the\nelectron density increases. We have studied the trends of this mobility minimum\nwith temperature, electron density, charging energy, ligand length, and\ndisorder. We account for the trends by a \"renormalized trap model\", in which\ncapturing an electron renormalizes a deep LNC trap into a shallow trap or a\nkinetic obstacle, depending on the charging energy. We verified this physical\npicture by constructing and analyzing heat maps of the mobile electrons in the\nBNS."
    },
    {
        "anchor": "Time-reversal breaking topological phase without Hall electric current\n  in a two-dimensional Dirac semimetal protected by nonsymmorphic symmetry: We investigate the topological phase derived by time-reversal breaking fields\nin a nonsymmorphic symmetry-protected two-dimensional Dirac semimetal. When the\nnonsymmorphic symmetry is preserved even in the presence of the field, the\ntwo-dimensional electronic states change into two distinct topological phases\nwith the insulating gap. One phase is well-known as quantum Hall states with\nchiral edge modes accompanying the Hall current, but the other one is an\nunconventional topological phase with helical edge modes in the absence of\ntime-reversal symmetry.",
        "positive": "Comment on \"Absence of electron dephasing at zero temperature\": The recent claim by Kirkpatrick and Belitz (cond-mat/0111398) that Ward\nidentities could be used to prove the absence of electron dephasing at T=0\ncontains serious flaws. These authors try to draw conclusions about dephasing\nfrom an analysis of the diffuson, which is not sensitive to this process. The\nCooperon, which does contain this information, is analyzed only in time\nreversal symmetric situations, which by assumption excludes any relaxation and\ndephasing. Hence, their analysis remains inconclusive for the problem in\nquestion."
    },
    {
        "anchor": "Path following and numerical continuation methods for non-linear MEMS\n  and NEMS: Non-linearities play an important role in micro- and nano- electromechanical\nsystem (MEMS and NEMS) design. In common electrostatic and magnetic actuators,\nthe forces and voltages can depend in a non-linear way on position, charge,\ncurrent and magnetic flux. Mechanical spring structures can cause additional\nnon-linearities via material, geometrical and contact effects. For the design\nand operation of non-linear MEMS devices it is essential to be able to model\nand simulate such non-linearities. However, when there are many degrees of\nfreedom, it becomes difficult to find all equilibrium solutions of the\nnon-linear equations and to determine their stability. In these cases path\nfollowing methods can be a powerful mathematical tool. In this paper we will\nshow how path following methods can be used to determine the equilibria and\nstability of electromechanical devices. Based on the energy, work and the\nHamiltonian of electromechanical systems (section 1), the equations of motion\n(section 2), the equilibrium (section 3) and stability conditions (section 6)\nare derived. Examples of path following simulations (section 4) in Mathematica\n(section 5), Matcont (section 7) and using FEM methods in Comsol (section 8)\nare given to illustrate the methods.",
        "positive": "Excess conductance of a spin-filtering quantum dot: The conductance G of a pair of single-channel point contacts in series, one\nof which is a spin filter, increases from 1/2 to 2/3 x e^2/h with more and more\nspin-flip scattering. This excess conductance was observed in a quantum dot by\nZumbuhl et al., and proposed as a measure for the spin relaxation time T_1.\nHere we present a quantum mechanical theory for the effect in a chaotic quantum\ndot (mean level spacing Delta, dephasing time tau_phi, charging energy e^2/C),\nin order to answer the question whether T_1 can be determined independently of\ntau_phi and C. We find that this is possible in a\ntime-reversal-symmetry-breaking magnetic field, when the average conductance\nfollows closely the formula <G>=(2e^2/h)(T_1+h/Delta)/(4T_1+3h/Delta)."
    },
    {
        "anchor": "Thermoelectric power factor in nanostructured materials with randomized\n  nanoinclusions: We investigate the electric and thermoelectric transport coefficients of\nnanocomposites using the Non-Equilibrium Greens Function (NEGF) method, which\ncan accurately capture the details of geometry and disorder in these\nstructures. We consider here two dimensional (2D) channels with embedded\nnanoinclusions (NIs) modelled as potential barriers of cylindrical shape and\nheight VB. We investigate the effect of randomness of the NIs on the\nthermoelectric power factor by varying the positions, diameter, and heights of\nthe barriers according to a Gaussian probability distribution. We find that the\npower factor shows indications of tolerance to variations in the parameters of\nthe NIs when the Fermi level is placed into the bands and VB approx. kBT. These\nresults could be experimentally relevant in the design of nanocomposites for\nthermoelectric applications.",
        "positive": "Collective magnetization dynamics in nano-arrays of thin FePd discs: We report on the magnetization dynamics of a square array of mesoscopic\ndiscs, fabricated from an iron palladium alloy film. The dynamics properties\nwere explored using ferromagnetic resonance measurements and micromagnetic\nsimulations. The obtained spectra exhibit features resulting from the\ninteractions between the discs, with a clear dependence on both temperature and\nthe direction of the externally applied field. We demonstrate a qualitative\nagreement between the measured and calculated spectra. Furthermore, we\ncalculated the mode profiles of the standing spin waves excited during a\ntime-dependent magnetic field excitations. The resulting maps confirm that the\nfeatures appearing in the ferromagnetic resonance absorption spectra originate\nfrom the temperature and directional dependent inter-disc interactions."
    },
    {
        "anchor": "Electron transport through multilevel quantum dot: Quantum transport properties through some multilevel quantum dots sandwiched\nbetween two metallic contacts are investigated by the use of Green's function\ntechnique. Here we do parametric calculations, based on the tight-binding\nmodel, to study the transport properties through such bridge systems. The\nelectron transport properties are significantly influenced by (a) number of\nquantized energy levels in the dots, (b) dot-to-electrode coupling strength,\n(c) location of the equilibrium Fermi energy $E_F$ and (d) surface disorder. In\nthe limit of weak-coupling, the conductance ($g$) shows sharp resonant peaks\nassociated with the quantized energy levels in the dots, while, they get\nsubstantial broadening in the strong-coupling limit. The behavior of the\nelectron transfer through these systems becomes much more clearly visible from\nour study of current-voltage ($I$-$V$) characteristics. In this context we also\ndescribe the noise power of current fluctuations ($S$) and determine the Fano\nfactor ($F$) which provides an important information about the electron\ncorrelation among the charge carriers. Finally, we explore a novel transport\nphenomenon by studying the surface disorder effect in which the current\namplitude increases with the increase of the surface disorder strength in the\nstrong disorder regime, while, the amplitude decreases in the limit of weak\ndisorder. Such an anomalous behavior is completely opposite to that of bulk\ndisordered system where the current amplitude always decreases with the\ndisorder strength. It is also observed that the current amplitude strongly\ndepends on the system size which reveals the finite quantum size effect.",
        "positive": "Quantum Dot Spin Filter in Resonant Tunneling and Kondo Regimes: A quantum dot with spin-orbit interaction can work as an efficient spin\nfilter if it is connected to N (> 2) external leads via tunnel barriers. When\nan unpolarized current is injected to a quantum dot from a lead, polarized\ncurrents are ejected to other leads. A two-level quantum dot is examined as a\nminimal model. First, we show that the spin polarization is markedly enhanced\nby resonant tunneling when the level spacing in the dot is smaller than the\nlevel broadening. Next, we examine the many-body resonance induced by the Kondo\neffect in the Coulomb blockade regime. A large spin current is generated in the\npresence of the SU(4) Kondo effect when the level spacing is less than the\nKondo temperature."
    },
    {
        "anchor": "Robust Dirac Point in Honeycomb Structure Nanoribbons with Zigzag Edges: The zigzag edge graphene nanoribbon, which is an antiferromagnetic insulator,\nis found from the density-function theory calculation to display a robust Dirac\npoint after N and B doping at the zigzag edge. More interestingly, we found\nthat the robust Dirac point is a common feature of the honeycomb structure\nnanoribbon with appropriate edge sites. The zigzag edge honeycomb nanoribbon is\ntherefore expected to provide a very useful platform for material design and\ndevelopment.",
        "positive": "Energy calculations of charged point defects on surfaces: We present a virtual ionic crystal (VIC) method to calculate energies of\ncharged point defects on surfaces. No artificial charge but an actual\nzero-dimensional (0D) species is introduced to charge a defect. Effect of\ndielectric substrate on lattice energy is depressed through suitable\nconfiguration of the unit cell. The lattice energy approximates to Madelung\nenergy with defect and 0D species considered as point charges in vacuum. Energy\nrequired to charge the defect is derived from charge quantity on the defect in\nVIC, energy of unit cell, and energy required to charge the 0D species."
    },
    {
        "anchor": "Quantum measurement characteristics of double-dot single electron\n  transistor: Owing to a few unique advantages, double-dot single electron transistor has\nbeen proposed as an alternative detector for charge states. In this work, we\npresent a further study for its signal-to-noise property, based on a full\nanalysis of the setup configuration symmetry. It is found that the\neffectiveness of the double-dot detector can approach that of an ideal\ndetector, if the symmetric capacitive coupling is taken into account. The\nquantum measurement efficiency is also analyzed, by comparing the measurement\ntime with the measurement-induced dephasing time.",
        "positive": "Optical conductivity and orbital magnetization of Floquet vortex states: Motivated by recent experimental demonstrations of Floquet topological\ninsulators, there have been several theoretical proposals for using structured\nlight, either spatial or spectral, to create other properties such as flat band\nand vortex states. In particular, the generation of vortex states in a massive\nDirac fermion insulator irradiated by light carrying nonzero orbital angular\nmomentum (OAM) has been proposed [Kim et al. Phys. Rev. B 105, L081301(2022)].\nHere, we evaluate the orbital magnetization and optical conductivity as\nphysical observables for such a system. We show that the OAM of light induces\nnonzero orbital magnetization and current density. The orbital magnetization\ndensity increases linearly as a function of OAM degree. In certain regimes, we\nfind that orbital magnetization density is independent of the system size,\nwidth, and Rabi frequency of light. It is shown that the orbital magnetization\narising from our Floquet theory is large and can be probed by magnetometry\nmeasurements. Furthermore, we study the optical conductivity for various types\nof electron transitions between different states such as vortex, edge, and bulk\nthat are present in the system. Based on conductance frequency peaks, a scheme\nfor the detection of vortex states is proposed."
    },
    {
        "anchor": "Tunable interface states between Floquet-Weyl semimetals: Weyl semimetals and nodal line semimetals are characterized by linear\nelectronic bands touching at zero-dimensional points and one-dimensional lines,\nrespectively. Recently, it has been predicted that nodal line semimetals can be\ndriven into tunable Floquet-Weyl semimetals by circularly polarized light.\nHere, we study the occurrence of interface states between two regions of a\nnodal line semimetal shined by two beams of light with opposite circular\npolarizations. Within a minimal model, we find remarkable modifications of the\nenergy structure by tuning the polarized light, such as the possible generation\nof van Hove singularities. Moreover, by adding a $\\delta$-doping of magnetic\nimpurities along the interfacial plane, we show the occurrence of a switchable\nand topologically non-trivial, vortex-like pseudo-spin pattern of the interface\nstates.",
        "positive": "Magnetic field induced valence band mixing in [111] grown semiconductor\n  quantum dots: We present a microscopic theory of the magnetic field induced mixing of\nheavy-hole states +/- 3/2 in GaAs droplet dots grown on (111)A substrates. The\nproposed theoretical model takes into account the striking dot shape with\ntrigonal symmetry revealed in atomic force microscopy. Our calculations of the\nhole states are carried out within the Luttinger Hamiltonian formalism,\nsupplemented with allowance for the triangularity of the confining potential.\nThey are in quantitative agreement with the experimentally observed\npolarization selection rules, emission line intensities and energy splittings\nin both longitudinal and transverse magnetic fields for neutral and charged\nexcitons in all measured single dots."
    },
    {
        "anchor": "Phase coherent transport in SrTiO3/LaAlO3 interfaces: The two dimensional electron gas formed between the two band insulators\nSrTiO3 and LaAlO3 exhibits a variety of interesting physical properties which\nmake it an appealing material for use in future spintronics and/or quantum\ncomputing devices. For this kind of applications electrons have to retain their\nphase memory for sufficiently long times or length. Using a mesoscopic size\ndevice we were able to extract the phase coherence length, and its temperature\nvariation. We find the dephasing rate to have a power law dependence on\ntemperature. The power depends on the temperature range studied and sheet\nresistance as expected from dephasing due to strong electron-electron\ninteractions.",
        "positive": "Ballistic electron transport exceeding 160 microns in an undoped\n  GaAs/AlGaAs FET: We report measurements of GaAs/AlGaAs undoped field-effect transistors in\nwhich two-dimensional electron gases (2DEGs) of exceptional quality and\nversatility are induced without modulation doping. Electron mobilities at T=4.2\nK and density 3 E11 /cm^2 exceed 4 E6 cm^2/Vs. At lower temperatures, there is\nan unusually large drop in scattering, such that the mobility becomes too high\nto measure in 100 micron samples. Below T=2.5 K, clear signatures of ballistic\ntravel over path lengths in excess of 160 microns are observed in magnetic\nfocusing experiments. Multiple reflections at the edges of the 2DEG indicate a\nhigh degree of specularity."
    },
    {
        "anchor": "Quantifying the intrinsic surface charge density and charge-transfer\n  resistance of the graphene-solution interface through bias-free low-level\n  charge measurement: Liquid-based bio-applications of graphene require a quantitative\nunderstanding of the graphene-liquid interface, with the surface charge density\nof adsorbed ions, the interfacial charge transfer resistance, and the\ninterfacial charge noise being of particular importance. We quantified these\nproperties through measurements of the zero-bias Faradaic charge-transfer\nbetween graphene electrodes and aqueous solutions of varying ionic strength\nusing a reproducible, low-noise, minimally perturbative charge measurement\ntechnique. The measurements indicated that adsorbed ions had a negative surface\ncharge density of approximately -32.8 mC m-2 and that the specific charge\ntransfer resistance was 6.5pm0.3 M${\\Omega}$ cm2. The normalized current noise\npower spectral density for all ionic concentrations tested collapsed onto a 1/f\ncharacteristic with ${\\alpha}$=1.1pm0.2. All the results are in excellent\nagreement with predictions of the theory for the graphene-solution interface.\nThis minimally-perturbative method for monitoring charge-transfer at the sub-pC\nscale exhibits low noise and ultra-low power consumption (~ fW), making it\nwell-suited for use in low-level bioelectronics in liquid environments.",
        "positive": "Proximitized Josephson junctions in highly-doped InAs nanowires robust\n  to optical illumination: We have studied the effects of optical-frequency light on proximitized\nInAs/Al Josephson junctions based on highly n-doped InAs nanowires at varying\nincident photon flux and at three different photon wavelengths. The\nexperimentally obtained IV curves were modeled using a shunted junction model\nwhich takes scattering at the contact interfaces into account. The Josephson\njunctions were found to be surprisingly robust, interacting with the incident\nradiation only through heating, whereas above the critical current our devices\nshowed non-thermal effects resulting from photon exposure. Our work provides\nimportant guidelines for the co-integration of Josephson junctions alongside\nquantum photonic circuits and lays the foundation for future work on\nnanowire-based hybrid photon detectors."
    },
    {
        "anchor": "Thermoelectric current in a graphene Cooper pair splitter: Thermoelectric effect generating electricity from thermal gradient and vice\nversa appears in numerous generic applications. Recently, an original prospect\nof thermoelectricity arising from the nonlocal Cooper pair splitting (CPS) and\nthe elastic co-tunneling (EC) in hybrid normal metal-superconductor-normal\nmetal (NSN) structures was foreseen. Here we demonstrate experimentally the\nexistence of non-local Seebeck effect in a graphene-based CPS device comprising\ntwo quantum dots connected to an aluminum superconductor and theoretically\nvalidate the observations. This non-local Seebeck effect offers an efficient\ntool for producing entangled electrons.",
        "positive": "Infernal and Exceptional Edge Modes: Non-Hermitian Topology Beyond the\n  Skin Effect: The classification of point gap topology in all local non-Hermitian symmetry\nclasses has been recently established. However, many entries in the resulting\nperiodic table have only been discussed in a formal setting and still lack a\nphysical interpretation in terms of their bulk-boundary correspondence. Here,\nwe derive the edge signatures of all two-dimensional phases with intrinsic\npoint gap topology. While in one dimension point gap topology invariably leads\nto the non-Hermitian skin effect, non-Hermitian boundary physics is\nsignificantly richer in two dimensions. We find two broad classes of\nnon-Hermitian edge states: (1) Infernal points, where a skin effect occurs only\nat a single edge momentum, while all other edge momenta are devoid of edge\nstates. Under semi-infinite boundary conditions, the point gap thereby closes\ncompletely, but only at a single edge momentum. (2) Non-Hermitian exceptional\npoint dispersions, where edge states persist at all edge momenta and furnish an\nanomalous number of symmetry-protected exceptional points. Surprisingly, the\nlatter class of systems allows for a finite, non-extensive number of edge\nstates with a well defined dispersion along all generic edge terminations.\nInstead, the point gap only closes along the real and imaginary eigenvalue\naxes, realizing a novel form of non-Hermitian spectral flow."
    },
    {
        "anchor": "Theory of optically controlled anisotropic polariton transport in\n  semiconductor double microcavities: Exciton polaritons in semiconductor microcavities exhibit many fundamental\nphysical effects, with some of them amenable to being controlled by external\nfields. The polariton transport is affected by the polaritonic spin-orbit\ninteraction, which is caused by the splitting of transverse-electric and\ntransverse-magnetic (TE-TM) modes. This is the basis for a polaritonic Hall\neffect, called optical spin Hall effect (OSHE), which is related to the\nformation of spin/polarization textures in momentum space, determining\nanisotropic ballistic transport, as well as related textures in real space.\nOwing to Coulombic interactions between the excitonic components of the\npolaritons, optical excitation of polaritons can affect the OSHE. We present a\ntheoretical analysis of the OSHE and its optical control in semiconductor\ndouble microcavities, i.e. two optically coupled cavities, which are\nparticularly well suited for the creation of polaritonic reservoirs that affect\nthe spin-texture-forming polaritons. The theory is formulated in terms of a set\nof double-cavity spinor-polariton Gross-Pitaevskii equations. Numerical\nsolutions feature, among other things, a controlled rotation of the spin\ntexture in momentum space. The theory also allows for an identification of the\neffective magnetic field component that determines the optical control in\nphenomenological pseudo-spin models in terms of exciton interactions and the\npolariton density in the second lower polariton branch.",
        "positive": "Phase transformation in two-dimensional covalent organic frameworks\n  under compressive loading: As a new class of two-dimensional (2D) materials, 2D covalent organic\nframeworks (COFs) are proven to possess remarkable electronic and magnetic\nproperties. However, their mechanical behaviours remain almost unexplored. In\nthis work, taking the recently synthesised dimethylmethylene-bridged\ntriphenylamine (DTPA) sheet as an example, we investigate the mechanical\nbehaviours of 2D COFs based on molecular dynamics simulations together with\ndensity functional theory calculations. A novel phase transformation is\nobserved in DTPA sheets when a relatively large in-plane compressive strain is\napplied to them. Specifically, the crystal structures of the transformed phases\nare topographically different when the compressive loading is applied in\ndifferent directions. The compression-induced phase transformation in DTPA\nsheets is attributed to the buckling of their kagome lattice structures and is\nfound to have significant impacts on their material properties. After the phase\ntransformation, Young's modulus, band gap and thermal conductivity of DTPA\nsheets are greatly reduced and become strongly anisotropic. Moreover, a large\nin-plane negative Poisson's ratio is found in the transformed phases of DTPA\nsheets. It is expected that the results of the compression-induced phase\ntransformation and its influence on the material properties observed in the\npresent DTPA sheets can be further extended to other 2D COFs, since most 2D\nCOFs possess a similar kagome lattice structure."
    },
    {
        "anchor": "Exactly-solvable problems for two-dimensional excitons: Several problems in mathematical physics relating to excitons in two\ndimensions are considered. First, a fascinating numerical result from a\ntheoretical treatment of screened excitons stimulates a re-evaluation of the\nfamiliar two-dimensional hydrogen atom. Formulating the latter problem in\nmomentum space leads to a new integral relation in terms of special functions,\nand fresh insights into the dynamical symmetry of the system are also obtained.\nA discussion of an alternative potential to model screened excitons is given,\nand the variable phase method is used to compare bound-state energies and\nscattering phase shifts for this potential with those obtained using the\ntwo-dimensional analogue of the Yukawa potential. The second problem relates to\nexcitons in a quantising magnetic field in the fractional quantum Hall regime.\nAn exciton against the background of an incompressible quantum liquid is\nmodelled as a few-particle neutral composite consisting of a positively-charged\nhole and several quasielectrons with fractional negative charge. A complete set\nof exciton basis functions is derived, and these functions are classified using\na result from the theory of partitions. Some exact results are obtained for\nthis complex few-particle problem.",
        "positive": "Acoustic square-root topological insulators: Square-root topological states are new topological phases, whose topological\nproperty is inherited from the square of the Hamiltonian. We realize the\nfirst-order and second-order square-root topological insulators in phononic\ncrystals, by putting additional cavities on connecting tubes in the acoustic\nSu-Schrieffer-Heeger model and the honeycomb lattice, respectively. Because of\nthe square-root procedure, the bulk gap of the squared Hamiltonian is doubled.\nIn both two bulk gaps, the square-root topological insulators possess multiple\nlocalized modes, i.e., the end and corner states, which are evidently confirmed\nby our calculations and experimental observations. We further propose a\nsecond-order square-root topological semimetal by stacking the decorated\nhoneycomb lattice to three dimensions."
    },
    {
        "anchor": "Broadband Purcell enhanced emission dynamics of quantum dots in linear\n  photonic crystal waveguides: The authors investigate the spontaneous emission dynamics of self-assembled\nInGaAs quantum dots embedded in GaAs photonic crystal waveguides. For an\nensemble of dots coupled to guided modes in the waveguide we report spatially,\nspectrally, and time-resolved photoluminescence measurements, detecting normal\nto the plane of the photonic crystal. For quantum dots emitting in resonance\nwith the waveguide mode, a ~21x enhancement of photoluminescence intensity is\nobserved as compared to dots in the unprocessed region of the wafer. This\nenhancement can be traced back to the Purcell enhanced emission of quantum dots\ninto leaky and guided modes of the waveguide with moderate Purcell factors up\nto ~4x. Emission into guided modes is shown to be efficiently scattered out of\nthe waveguide within a few microns, contributing to the out-of-plane emission\nand allowing the use of photonic crystal waveguides as broadband,\nefficiency-enhancing structures for surface-emitting diodes or single photon\nsources.",
        "positive": "Nanomechanical Resonators: Toward Atomic Scale: The quest for realizing and manipulating ever smaller man-made movable\nstructures and dynamical machines has spurred tremendous endeavors, led to\nimportant discoveries, and inspired researchers to venture to new grounds.\nScientific feats and technological milestones of miniaturization of mechanical\nstructures have been widely accomplished by advances in machining and\nsculpturing ever shrinking features out of bulk materials such as silicon. With\nthe flourishing multidisciplinary field of low-dimensional nanomaterials,\nincluding one-dimensional (1D) nanowires/nanotubes, and two-dimensional (2D)\natomic layers such as graphene/phosphorene, growing interests and sustained\nefforts have been devoted to creating mechanical devices toward the ultimate\nlimit of miniaturization--genuinely down to the molecular or even atomic scale.\nThese ultrasmall movable structures, particularly nanomechanical resonators\nthat exploit the vibratory motion in these 1D and 2D nano-to-atomic-scale\nstructures, offer exceptional device-level attributes, such as ultralow mass,\nultrawide frequency tuning range, broad dynamic range, and ultralow power\nconsumption, thus holding strong promises for both fundamental studies and\nengineering applications. In this Review, we offer a comprehensive overview and\nsummary of this vibrant field, present the state-of-the-art devices and\nevaluate their specifications and performance, outline important achievements,\nand postulate future directions for studying these miniscule yet intriguing\nmolecular-scale machines."
    },
    {
        "anchor": "Signatures of spin pairing in a quantum dot in the Coulomb blockade\n  regime: Coulomb blockade resonances are measured in a GaAs quantum dot in which both\nshape deformations and interactions are small. The parametric evolution of the\nCoulomb blockade peaks shows a pronounced pair correlation in both position and\namplitude, which is interpreted as spin pairing. As a consequence, the\nnearest-neighbor distribution of peak spacings can be well approximated by a\nsmeared bimodal Wigner surmise, provided that interactions which go beyond the\nconstant interaction model are taken into account.",
        "positive": "Hybrid higher-order skin-topological effect in hyperbolic lattices: We investigate the non-Hermitian Haldane model on hyperbolic $\\{8, 3\\}$ and\n$\\{12, 3\\}$ lattices, and showcase its intriguing topological properties in the\nsimultaneous presence of non-Hermitian effect and hyperbolic geometry. From\nbulk descriptions of the system, we calculate the real space non-Hermitian\nChern numbers by generalizing the method from its Hermitian counterpart and\npresent corresponding phase diagram of the model. For boundaries, we find that\nskin-topological modes appear in the range of the bulk energy gap under certain\nboundary conditions, which can be explained by an effective one-dimensional\nzigzag chain model mapped from hyperbolic lattice boundary. Remarkably, these\nskin-topological modes are localized at specific corners of the boundary,\nconstituting a hybrid higher-order skin-topological effect on hyperbolic\nlattices."
    },
    {
        "anchor": "Beats of the Magnetocapacitance Oscillations in Lateral Semiconductor\n  Superlattices: We present calculations on the magnetocapacitance of the two-dimensional\nelectron gas in a lateral semiconductor superlattice under two-dimensional weak\nperiodic potential modulation in the presence of a perpendicular magnetic\nfield. Adopting a Gaussian broadening of magnetic-field-dependent width in the\ndensity of states, we present explicit and simple expressions for the\nmagnetocapacitance, valid for the relevant weak magnetic fields and modulation\nstrengths. As the modulation strength in both directions increase, beats of the\nmagnetocapacitance oscillations are observed, in the low magnetic field range\n(Weiss-oscillations regime), which are absent in the one-dimensional weak\nmodulation case.",
        "positive": "Electrical pump-and-probe study of spin singlet-triplet relaxation in a\n  quantum dot: Spin relaxation from a triplet excited state to a singlet ground state in a\nsemiconductor quantum dot is studied by employing an electrical pump-and-probe\nmethod. Spin relaxation occurs via cotunneling when the tunneling rate is\nrelatively large, confirmed by a characteristic square dependence of the\nrelaxation rate on the tunneling rate. When cotunneling is suppressed by\nreducing the tunneling rate, the intrinsic spin relaxation is dominated by\nspin-orbit interaction. We discuss a selection rule of the spin-orbit\ninteraction based on the observed double-exponential decay of the triplet\nstate."
    },
    {
        "anchor": "Phonon cooling of nanomechanical beams with tunnel junctions: We demonstrate electronic cooling of 1D phonon modes in suspended nanowires\nfor the first time, using normal metal--insulator--superconductor (NIS) tunnel\njunctions. Simultaneous cooling of both electrons and phonons to a common\ntemperature was achieved. In comparison with non-suspended devices, better\ncooling performance is achieved in the whole operating range of bath\ntemperatures between 0.1-0.7 K. The observed low-temperature thermal transport\ncharacteristics are consistent with scattering of ballistic phonons at the\nnanowire-bulk contact as being the mechanism limiting thermal transport. At the\nlowest bath temperature of the experiment $\\sim$ 100 mK, both phonons and\nelectrons in the beam were cooled down to 42 mK, which is below the\nrefrigerator bath temperature.",
        "positive": "Approaching ideal weak link behavior with three dimensional aluminum\n  nanobridges: We present transport measurements of unshunted dc superconducting quantum\ninterference devices (SQUIDs) consisting of 30 nm wide aluminum nanobridges of\nvarying length L contacted with two and three dimensional banks. 3D nanobridge\nSQUIDs with L $\\leq$ 150 nm (approximately 3-4 times the superconducting\ncoherence length) exhibit $\\approx 70%$ critical current modulation with\napplied magnetic field, approaching the theoretical limit for an ideal short\nmetallic weak link. In contrast, 2D nanobridge SQUIDs exhibit significantly\nlower critical current modulation. This enhanced nonlinearity makes 3D\nnanobridge Josephson junctions well suited to optimize sensitivity in weak link\nSQUID magnetometers as well as realize ultra low-noise amplifiers and qubits."
    },
    {
        "anchor": "Elastically Relaxed Free-standing Strained-Si Nanomembranes: Strain plays a critical role in the properties of materials. In silicon and\nsilicon-germanium, strain provides a mechanism for control of both carrier\nmobility and band offsets. In materials integra-tion, strain is typically tuned\nthrough the use of dislocations and elemental composition. We demonstrate a\nversatile method to control strain, by fabricating membranes in which the final\nstrain state is controlled by elastic strain sharing, i.e., without the\nformation of defects. We grow Si/SiGe layers on a substrate from which they can\nbe released, forming nanomembranes. X-ray diffraction measurements confirm a\nfinal strain predicted by elasticity theory. The effec-tiveness of elastic\nstrain to alter electronic properties is demonstrated by low-temperature\nlongi-tudinal-Hall effect measurements on a strained-Si quantum well before and\nafter release. Elastic strain sharing and film transfer offers an intriguing\npath towards complex, multiple-layer struc-tures in which each layer's\nproperties are controlled elastically, without the introduction of unde-sirable\ndefects.",
        "positive": "Quantum Phase Transition in Hall Conductivity on an Anisotropic Kagome\n  Lattice: We study the quantum Hall effect(QHE) on the Kagom\\'{e} lattice with\nanisotropy in one of the hopping integrals. We find a new type of QHE\ncharacterized by the quantization rules for Hall conductivity\n$\\sigma_{xy}=2ne^{2}/h$ and Landau Levels $E(n)=\\pm v_{F}\\sqrt{(n+1/2)\\hbar\nBe}$ ($n$ is an integer), which is different from any known type. This phase\nevolves from the QHE phase with $\\sigma_{xy}=4(n+1/2)e^{2}/h$ and $E(n)=\\pm\nv_{F}\\sqrt{2n\\hbar Be}$ in the isotropic case, which is realized in a system\nwith massless Dirac fermions (such as in graphene). The phase transition does\nnot occur simultaneously in all Hall plateaus as usual but in sequence from low\nto high energies, with the increase of hopping anisotropy."
    },
    {
        "anchor": "Energy dependence of current noise in double-barrier\n  normal-superconducting structures: We study theoretically the current-noise energy dependence for a N-N'-S\nstructure, where N and S stand for bulk normal metal and superconductor,\nrespectively, and N' for a short diffusive normal metal. Using quasiclassical\ntheory of current fluctuations we obtain explicit expressions for the noise\nvalid for arbitrary distributions of channel transparencies on both junctions.\nThe differential Fano factor turns out to depend on both junction\ntransparencies and the ratio of the two conductances. We conclude that\nmeasurement of differential conductance and noise can be used to probe the\nchannel distribution of the interfaces.",
        "positive": "Zeeman ratchets: pure spin current generation in mesoscopic conductors\n  with non-uniform magnetic fields: We consider the possibility to employ a quantum wire realized in a\ntwo-dimensional electron gas (2DEG) as a spin ratchet. We show that a net spin\ncurrent without accompanying net charge transport can be induced in the\nnonlinear regime by an unbiased external driving via an ac voltage applied\nbetween the contacts at the ends of the quantum wire. To achieve this we make\nuse of the coupling of the electron spin to inhomogenous magnetic fields\ncreated by ferromagnetic stripes patterned on the semiconductor heterostructure\nthat harbours the 2DEG. Using recursive Green function techniques we\nnumerically study two different setups, consisting of one and two ferromagnetic\nstripes, respectively."
    },
    {
        "anchor": "SU(4) Kondo entanglement in double quantum dot devices: We analyze, from a quantum information theory perspective, the possibility of\nrealizing a SU(4) entangled Kondo regime in semiconductor double quantum dot\ndevices. We focus our analysis on the ground state properties and consider the\ngeneral experimental situation where the coupling parameters of the two quantum\ndots differ. We model each quantum dot with an Anderson type Hamiltonian\nincluding an interdot Coulomb repulsion and tunnel couplings for each quantum\ndot to independent fermionic baths. We find that the spin and pseudospin\nentanglements can be made equal, and the SU(4) symmetry recovered, if the gate\nvoltages are chosen in such a way that the average charge occupancies of the\ntwo quantum dots are equal, and the double occupancy on the double quantum dot\nis suppressed. We present density matrix renormalization group numerical\nresults for the spin and pseudospin entanglement entropies, and analytical\nresults for a simplified model that captures the main physics of the problem.",
        "positive": "Single-photon controlled thermospin transport in a resonant ring-cavity\n  system: Cavity-coupled nanoelectric devices hold great promise for quantum technology\nbased on coupling between electron-spins and photons. In this study, we\napproach the description of these effects through the modeling of a nanodevice\nusing a quantum master equation. We assume a quantum ring is coupled to two\nexternal leads with different temperatures and embedded in a cavity with a\nsingle photon mode. Thermospin transport of the ring-cavity system is\ninvestigated by tuning the Rashba coupling constant and the electron-photon\ncoupling strength. In the absence of the cavity, the temperature gradient of\nthe leads causes a generation of a thermospin transport in the ring system. It\nis observed that the induced spin polarization has a maximum value at the\ncritical value of the Rashba coupling constant corresponding to the\nAharonov-Casher destructive interference, where the thermospin current is\nefficiently suppressed. Embedded in a photon cavity with the photon energy\nclose to a resonance with the energy spacing between lowest states of the\nquantum ring, a Rabi splitting in the energy spectrum is observed. Furthermore,\nphoton replica states are formed leading to a reduction in the thermospin\ncurrent."
    },
    {
        "anchor": "How the quantum ring shape influences its energy spectrum: We propose a new approach for modeling the quantum ring single particle\nenergy spectrum. The approach is based on separation of variables in the\nSchr\\\"odinger equation in oblate spheroidal coordinates. We consider a model of\na spheroidal quantum ring with infinite walls. Our simple model allowed us to\nstudy the spectra for quantum rings of different shapes. The spectrum is\ncalculated for the ground and several excited states and the ring shape\ndependence of the spectrum is demonstrated. The spectrum can demonstrate\nparabolic or non-parabolic dependence on the magnetic quantum number for\ndifferent shapes of the ring",
        "positive": "Evolution of the topologically protected surface states in\n  superconductor $\u03b2$-Bi$_{2}$Pd from the three-dimensional to the\n  two-dimensional limit: The recent discovery of topologically protected surface states in the\nnoncentrosymmetric $\\alpha$-BiPd and the centrosymmetric $\\beta$-Bi$_{2}$Pd has\nrenewed the interest in the Bi-Pd family of superconductors. Here, we employ\nfirst-principles calculations to investigate the structure, electronic, and\ntopological features of $\\beta$-Bi$_{2}$Pd, in bulk and in thin films of\nvarious thicknesses. We find that the Van der Waals dispersion corrections are\nimportant for reproducing the experimental structural parameters, while the\nspin-orbit interaction is critical for properly describing the appearance of\ntopological electronic states. By increasing the thickness of the slab, the\nDirac-cone surface states and the Rashba-type surface states gradually emerge\nat 9 and 11 triple-layers."
    },
    {
        "anchor": "Plasmonic mediated nucleation of resonant nano-cavities in metallic\n  layers: We predict plasmonic mediated nucleation of pancake shaped resonant\nnano-cavities in metallic layers that are penetrable to laser fields. The\nunderlying physics is that the cavity provides a narrow plasmonic resonance\nthat maximizes its polarizability in an external field. The resonance yields a\nsignificant energy gain making the formation of such cavities highly favorable.\nPossible implications include nano-optics and generation of the dielectric bits\nin conductive films that underlie the existing optical recording phase change\ntechnology.",
        "positive": "Highly tuneable hole quantum dots in Ge-Si core-shell nanowires: We define single quantum dots of lengths varying from 60 nm up to nearly half\na micron in Ge-Si core-shell nanowires. The charging energies scale inversely\nwith the quantum dot length between 18 and 4 meV. Subsequently, we split up a\nlong dot into a double quantum dot with a separate control over the tunnel\ncouplings and the electrochemical potential of each dot. Both single and double\nquantum dot configurations prove to be very stable and show excellent control\nover the electrostatic environment of the dots, making this system a highly\nversatile platform for spin-based quantum computing."
    },
    {
        "anchor": "Bulk transport through superconducting hybrid structures in HgTe quantum\n  wells: We investigate the subgap bulk transport through short and wide\nsuperconducting hybrid structures based on HgTe quantum wells (QWs). We show\nthat the differential conductance of a normal metal-insulator-superconductor\n(NIS) proximity structure behaves in a qualitatively different way with respect\nto the topological phase of the HgTe QW. We compare the differential\nconductance for the NIS structure within the wave-matching method based on the\nBogoliubov-de Gennes equation and the matrix method based on the normal-state\nscattering matrix and find that the two models agree for highly-doped N and S\ncontacts. We also show that the effect of a possible Rashba spin-orbit\ninteraction on the differential conductance can be significant for weakly doped\nN and S contacts. Our findings should be important in samples with a large\naspect ratio where bulk contributions in transport are dominant.",
        "positive": "Imaging surface plasmon polaritons using proximal self-assembled InGaAs\n  quantum dots: We present optical investigations of hybrid plasmonic nanosystems consisting\nof lithographically defined plasmonic Au-waveguides or beamsplitters on GaAs\nsubstrates coupled to proximal self-assembled InGaAs quantum dots. We designed\na sample structure that enabled us to precisely tune the distance between\nquantum dots and the sample surface during nano-fabrication and demonstrated\nthat non-radiative processes do not play a major role for separations down to\n$\\sim 10 nm$. A polarized laser beam focused on one end of the plasmonic\nnanostructure generates propagating surface plasmon polaritons that, in turn,\ncreate electron-hole pairs in the GaAs substrate during propagation. These free\ncarriers are subsequently captured by the quantum dots $\\sim 25 nm$ below the\nsurface, giving rise to luminescence. The intensity of the spectrally\nintegrated quantum dot luminescence is used to image the propagating plasmon\nmodes. As the waveguide width reduces from $5 \\mu m$ to $1 \\mu m$, we clearly\nobserve different plasmonic modes at the remote waveguide end, enabling their\ndirect imaging in real space. This imaging technique is applied to a plasmonic\nbeamsplitter facilitating the determination of the splitting ratio between the\ntwo beamsplitter output ports as the interaction length $L_i$ is varied. A\nsplitting ratio of $50:50$ is observed for $L_i\\sim 9\\pm1 \\mu m$ and $1 \\mu m$\nwide waveguides for excitation energies close to the GaAs band edge. Our\nexperimental findings are in good agreement with mode profile and finite\ndifference time domain simulations for both waveguides and beamsplitters."
    },
    {
        "anchor": "Paramagnetic resonance in spin-polarized disordered Bose-Einstein\n  condensates: We study the pseudo-spin density response of a disordered two-dimensional\nspin-polarized Bose gas of exciton polaritons to weak alternating magnetic\nfield, assuming that one of the spin states of the doublet is macroscopically\noccupied and Bose-condensed while the occupation of the other state remains\nmuch smaller. We calculate spatial and temporal dispersions of spin\nsusceptibility of the gas taking into account spin-flip processes due to the\ntransverse-longitudinal splitting. Further, we use the Bogoliubov theory of\nweakly-interacting gases and show that the time-dependent magnetic field power\nabsorption exhibits double resonance structure corresponding to two particle\nspin states (contrast to paramagnetic resonance in regular spin-polarized\nelectron gas). We analyze the widths of these resonances caused by scattering\non the disorder and show that, in contrast with the ballistic regime, in the\npresence of impurities, the polariton scattering on them is twofold: scattering\non the impurity potential directly and scattering on the spatially fluctuating\ncondensate density caused by the disorder. As a result, the width of the\nresonance associated with the Bose-condensed spin state can be surprizingly\nnarrow in comparison with the width of the resonance associated with the\nnon-condensed state.",
        "positive": "Equilibrium magnetization of a quasispherical cluster of single-domain\n  particles: Equilibrium magnetization curve of a rigid finite-size spherical cluster of\nsingle-domain particles is investigated both numerically and analytically. The\nspatial distribution of particles within the cluster is random. Dipole-dipole\ninteractions between particles are taken into account. The particles are\nmonodisperse. It is shown, using the stochastic Landau-Lifshitz-Gilbert\nequation that the magnetization of such clusters is generally lower than\npredicted by the classical Langevin model. In a broad range of dipolar coupling\nparameters and particle volume fractions, the cluster magnetization in the weak\nfield limit can be successfully described by the modified mean-field theory,\nwhich was originally proposed for the description of concentrated ferrofluids.\nIn moderate and strong fields, the theory overestimates the cluster\nmagnetization. However, predictions of the theory can be improved by adjusting\nthe corresponding mean-field parameter. If magnetic anisotropy of particles is\nadditionally taken into account and if the distribution of the particles' easy\naxes is random and uniform, then the cluster equilibrium response is even\nweaker. The decrease of the magnetization with increasing anisotropy constant\nis more pronounced at large applied fields. The phenomenological generalization\nof the modified mean-field theory, that correctly describes this effect for\nsmall coupling parameters, is proposed."
    },
    {
        "anchor": "A proposed spin qubit CNOT gate robust against noisy coupling: We propose an implementation of the two-qubit gate in a quantum dot spin\nqubit system which is immune to charge noise problems. Our proposed\nimplementation, if it could be realized in a physical system, would have the\nadvantage of being robust against uncertainties and fluctuations in the tunnel\ncoupling and barrier gate voltage pulse area. The key idea is to introduce an\nauxiliary dot and use an analog to the stimulated Raman adiabatic passage pulse\nsequence in three-level atomic systems, often referred to in the context of\nelectron transport in quantum dot systems as Coherent Tunneling by Adiabatic\nPassage. Spin-dependent tunneling opens the possibility of performing two-qubit\ngate operations by this method.",
        "positive": "Quantum Point Contacts and Coherent Electron Focusing: I. Introduction\n  II. Electrons at the Fermi level\n  III. Conductance quantization of a quantum point contact\n  IV. Optical analogue of the conductance quantization\n  V. Classical electron focusing\n  VI. Electron focusing as a transmission problem\n  VII. Coherent electron focusing (Experiment, Skipping orbits and magnetic\nedge states, Mode-interference and coherent electron focusing)\n  VIII. Other mode-interference phenomena"
    },
    {
        "anchor": "Inverse Edelstein effect of the surface states of a topological\n  insulator: The surface states of three-dimensional topological insulators posses the\nunique property of spin-momentum interlocking. This property gives rise to the\ninteresting inverse Edelstein effect (IEE), in which an applied spin bias $\\mu$\nis converted to a measurable charge voltage difference $V$. We develop a\nsemiclassical theory for the IEE of the surface states of\n$\\text{Bi}_2\\text{Se}_3$ thin films, which is applicable from the ballistic\nregime to diffusive regime. We find that the IEE efficiency ratio\n$\\gamma=V/\\mu$ exhibits universal dependence on sample size, and approaches\n$\\pi/4$ in the ballistic limit and $1$ in the diffusive limit.",
        "positive": "Symmetry fingerprints of a benzene single-electron transistor: The interplay between Coulomb interaction and orbital symmetry produces\nspecific transport characteristics in molecular single electron transistors\n(SET) that can be considered as the fingerprints of the contacted molecule.\nSpecifically we predict, for a benzene SET, selective conductance suppression\nand the appearance of negative differential conductance when changing the\ncontacts from para to meta configuration. Both effects originate from\ndestructive interference in transport involving states with orbital degeneracy."
    },
    {
        "anchor": "Theory of NMR in semiconductor quantum point contact devices: We describe how a local non-equilibrium nuclear polarisation can be generated\nand detected by electrical means in a semiconductor quantum point contact\ndevice. We show that measurements of the nuclear spin relaxation rate will\nprovide clear signatures of the interaction mechanism underlying the \"0.7\"\nconductance anomaly. Our analysis illustrates how nuclear magnetic resonance\nmethods, which are used extensively to study strongly-correlated electron\nphases in bulk materials, can be made to play a similarly important role in\nnanoscale devices.",
        "positive": "A Two-Kind-Boson Mixture Honeycomb Hamiltonian of Bloch\n  Exciton-Polaritons: The electronic bandstructure of a solid is a collection of allowed bands\nseparated by forbidden bands, revealing the geometric symmetry of the crystal\nstructures. Comprehensive knowledge of the bandstructure with band parameters\nexplains intrinsic physical, chemical and mechanical properties of the solid.\nHere we report the artificial polaritonic bandstructures of two-dimensional\nhoneycomb lattices for microcavity exciton-polaritons using GaAs semiconductors\nin the wide-range detuning values, from cavity-photon-like (red-detuned) to\nexciton-like (blue-detuned) regimes. In order to understand the experimental\nbandstructures and their band parameters, such as gap energies, bandwidths,\nhopping integrals and density of states, we originally establish a polariton\nband theory within an augmented plane wave method with two-kind-bosons, cavity\nphotons trapped at the lattice sites and freely moving excitons. In particular,\nthis two-kind-band theory is absolutely essential to elucidate the exciton\neffect in the bandstructures of blue-detuned exciton-polaritons, where the\nflattened exciton-like dispersion appears at larger in-plane momentum values\ncaptured in our experimental access window. We reach an excellent agreement\nbetween theory and experiments in all detuning values."
    },
    {
        "anchor": "Topological classification of quasi-periodically driven quantum systems: Few level quantum systems driven by $n_\\mathrm{f}$ incommensurate fundamental\nfrequencies exhibit temporal analogues of non-interacting phenomena in\n$n_\\mathrm{f}$ spatial dimensions, a consequence of the generalisation of\nFloquet theory in frequency space. We organise the fundamental solutions of the\nfrequency lattice model for $n_\\mathrm{f}=2$ into a quasi-energy band structure\nand show that every band is classified by an integer Chern number. In the\ntrivial class, all bands have zero Chern number and the quasi-periodic dynamics\nis qualitatively similar to Floquet dynamics. The topological class with\nnon-zero Chern bands has dramatic dynamical signatures, including the pumping\nof energy from one drive to the other, chaotic sensitivity to initial\nconditions, and aperiodic time dynamics of expectation values. The topological\nclass is however unstable to generic perturbations due to exact level crossings\nin the quasi-energy spectrum. Nevertheless, using the case study of a spin in a\nquasi-periodically varying magnetic field, we show that topological class can\nbe realised at low frequencies as a pre-thermal phase, and at finite\nfrequencies using counter-diabatic tools.",
        "positive": "Spin-current-mediated rapid magnon localisation and coalescence after\n  ultrafast optical pumping of ferrimagnetic alloys: Sub-picosecond magnetisation manipulation via femtosecond optical pumping has\nattracted wide attention ever since its original discovery in 1996. However,\nthe spatial evolution of the magnetisation is not yet well understood, in part\ndue to the difficulty in experimentally probing such rapid dynamics. Here, we\nfind evidence of rapid magnetic order recovery in materials with perpendicular\nmagnetic anisotropy via nonlinear magnon processes. We identify both\nlocalisation and coalescence regimes, whereby localised magnetic textures\nnucleate and subsequently evolve in accordance with a power law formalism.\nCoalescence is observed for optical excitations both above and below the\nswitching threshold. Simulations indicate that the ultrafast generation of\nnoncollinear magnetisation via optical pumping establishes exchange-mediated\nspin currents with an equivalent 100% spin polarised charge current density of\n$10^8$ A/cm$^2$. Such large spin currents precipitate rapid recovery of\nmagnetic order after optical pumping. These processes suggest an ultrafast\noptical route for the stabilization of desired meta-stable states, e.g.,\nisolated skyrmions."
    },
    {
        "anchor": "Optically Induced Aggregation In Single Walled Carbon Nanotubes\n  Functionalized with Bacteriorhodopsin: We report optically induced aggregation and subsequent separation of\nselective single-walled carbon nanotubes (SWNT) functionalized with\nbacteriorhodopsin in the aqueous solution. Well-dispersed, aqueous solutions of\nhydrophobic pristine SWNT were prepared using a biocompatible surfactant.\nDispersed SWNTs were then functionalized with biologically synthesized,\noptically active purple membrane from Halobacterium salinarium S9.\nBacteriorhodopsin is the optically active protein of the purple membrane.\nCharge transfer and interactions between an optically active purple membrane\n(PM) and nanotubes affect the stability of dispersion. Enhanced aggregation in\nthese well-dispersed, stable solutions of SWNT were observed under a lamp with\nbroadband visible frequency. Concentration of SWNTs shows rapid, optically\ninduced aggregation of over 70% in 4 hours. This enhanced rate of aggregation\nunder light was further investigated using specific band pass filters. The rate\nof aggregation was found to depend on the absorption band of the optically\nactive PM. Raman spectra of the optically separated, bio-nano hybrid complexes\nshow stable, preferential binding between the optically active PM and SWNTs of\nspecific diameters.",
        "positive": "Embedded metal nanopatterns for near-field scattering-enhanced optical\n  absorption: Simulations of metal nanopatterns embedded in a thin photovoltaic absorber\nshow significantly enhanced absorbance within the semiconductor, with a more\nthan 300% increase for {\\lambda} = 800 nm. Integrating with AM1.5 solar\nirradiation, this yields a 70% increase in simulated short circuit current\ndensity in a 60 nm amorphous silicon film. Embedding such metal patterns inside\nan absorber maximally utilizes enhanced electric fields that result from\nintense, spatially organized, near-field scattering in the vicinity of the\npattern. Appropriately configured (i.e. with a thin insulating coating), this\noptical metamedium architecture may be useful for increasing photovoltaic\nefficiency in thin film solar cells, including offering prospects for realistic\nultrathin hot electron cells."
    },
    {
        "anchor": "Friction and Radiative Heat Exchange in a System of Two Parallel Plates\n  Moving Sideways : Levin-Polevoy-Rytov Theory Revisited: It is shown that the fundamental results obtained in the works by Levine,\nPolevoi, Rytov (1980) and Polevoi (1990), based on the\nfluctuation-electromagnetic theory by Levine and Rytov, adequately describe the\nrate of radiative heat exchange and the frictional force in a system of two\nparallel thick plates in relative lateral motion. A numerically calculated\nfriction force for good metals and thin gaps turns out to be by a factor 107\nhigher than earlier obtained by Polevoi and increases with increasing\nconductivity of the metals.",
        "positive": "Quantum Breakdown of the Quantized Hall Insulator: We present an analytical scaling theory for localization in a two-dimensional\nhierarchical network model that is designed to represent phase-coherent\nelectron transport in the quantum-Hall regime. Scaling expressions for both the\nlongitudinal and Hall resistivities are derived. In agreement with recent\nnumerical studies, we find that the Hall resistivity is quantized in the\nmetallic phase but diverges in the insulating phase. This suggests that the\ncharacteristics of a quantized Hall insulator can occur only in the presence of\na strong dephasing mechanism."
    },
    {
        "anchor": "Electronic Raman Scattering On Individual Single Walled Carbon Nanotubes: We report experimental measurements of electronic Raman scattering under\nresonant conditions by electrons in individual single-walled carbon nanotubes\n(SWNTs). The inelastic Raman scattering at low frequency range reveals a single\nparticle excitation feature and the dispersion of electronic structure around\nthe center of Brillouin zone of a semiconducting SWNT (14, 13) is extracted.",
        "positive": "Dynamic nuclear polarization induced by breakdown of fractional quantum\n  Hall effect: We study dynamic nuclear polarization (DNP) induced by breakdown of the\nfractional quantum Hall (FQH) effect. We find that voltage-current\ncharacteristics depend on current sweep rates at the quantum Hall states of\nLandau level filling factors $\\nu$ = 1, 2/3, and 1/3. The sweep rate dependence\nis attributed to DNP occurring in the breakdown regime of FQH states. Results\nof a pump and probe experiment show that the polarities of the DNP induced in\nthe breakdown regimes of the FQH states is opposite to that of the DNP induced\nin the breakdown regimes of odd-integer quantum Hall states."
    },
    {
        "anchor": "Radiative cooling of nanoparticles close to a surface: We study the radiative cooling of polar and metallic nanoparticles immersed\nin a thermal bath close to a partially reflecting surface. The dynamics of\nrelaxation is investigated at different distances from the surface, i.e., in\nthe near-field and far-field zones. We demonstrate the existence of an\noscillating behavior for the thermal relaxation time with respect to the\nseparation distance from the surface, an analog of Friedel oscillations in\nFermi liquids.",
        "positive": "Implementation of transmission functions for an optimized three-terminal\n  quantum dot heat engine: We consider two modifications of a recently proposed three-terminal quantum\ndot heat engine. First, we investigate the necessity of the thermalization\nassumption, namely that electrons are always thermalized by inelastic processes\nwhen traveling across the cavity where the heat is supplied. Second, we analyze\nvarious arrangements of tunneling-coupled quantum dots in order to implement a\ntransmission function that is superior to the Lorentzian transmission function\nof a single quantum dot. We show that the maximum power of the heat engine can\nbe improved by about a factor of two, even for a small number of dots, by\nchoosing an optimal structure."
    },
    {
        "anchor": "Topological matter: graphene and superfluid 3He: Physics of graphene and physics of superfluid phases of 3He have many common\nfeatures. Both systems are topological materials where quasiparticles behave as\nrelativistic massless (Weyl, Majorana or Dirac) fermions. We formulate the\npoints where these features are overlapping. This will allow us to use graphene\nfor study the properties of superfluid 3He, to use superfluid 3He for study the\nproperties of graphene, and to use the combination to study the physics of\ntopological quantum vacuum. We suggest also some particular experiments with\nsuperfluid 3He using graphene as an atomically thin membrane impenetrable for\nHe atoms but allowing for spin, momentum and energy transfer.",
        "positive": "Spin decoherence in graphene quantum dots due to hyperfine interaction: Carbon based systems are prominent candidates for a solid-state spin-qubit\ndue to weak spin-orbit and hyperfine interactions in combination with a low\nnatural abundance of spin carrying isotopes. We consider the effect of the\nhyperfine interaction on the coherence of an electron-spin localized in a\ngraphene quantum dot. It is known, that the hyperfine interaction in these\nsystems is anisotropic promising interesting physics. We calculate the dynamics\nof an electron spin surrounded by a bath of nuclear spins in a non-Markovian\napproach using a generalized master equation. Considering a general form of the\nhyperfine interaction, we are able to extend the range of validity of our\nresults to other systems beyond graphene. For large external magnetic fields,\nwe find within Born approximation that the electron spin state is conserved up\nto small corrections, which oscillate with a frequency determined by the\nhyperfine interaction. The amplitude of these oscillations decays with a power\nlaw, where its initial value depends on the specific form of the anisotropy.\nAnalyzing this in more detail, we identify two distinct classes of anisotropy,\nwhich can be both found in graphene depending on the orientation of the\nexternal magnetic field with respect to the carbon layer."
    },
    {
        "anchor": "Nonlinear mode-coupling and synchronization of a vacuum-trapped\n  nanoparticle: We study the dynamics of a laser-trapped nanoparticle in high vacuum. Using\nparametric coupling to an external excitation source, the linewidth of the\nnanoparticle's oscillation can be reduced by three orders of magnitude. We show\nthat the oscillation of the nanoparticle and the excitation source are\nsynchronized, exhibiting a well-defined phase relationship. Furthermore, the\nexternal source can be used to controllably drive the nanoparticle into the\nnonlinear regime, thereby generating strong coupling between the different\ntranslational modes of the nanoparticle. Our work contributes to the\nunderstanding of the nonlinear dynamics of levitated nanoparticles in high\nvacuum and paves the way for studies of pattern formation, chaos, and\nstochastic resonance.",
        "positive": "Kondo Impurity in a Mesoscopic Ring: Charge Persistent Current: We study the influence of a magnetic impurity or ultrasmall quantum dot on\nthe charge persistent current of a mesoscopic ring. The system consists of\nelectrons in a one-dimensional ring threaded by spin-dependent\nAharonov-Bohm/Casher fluxes, coupled via an antiferromagnetic exchange\ninteraction to a localized electron. By passing to a basis of electron states\nwith definite parities, the problem is mapped onto a Kondo model for the\neven-parity channel plus free electrons in the odd-parity channel. States of\nopposite parities decouple for values of the flux corresponding to periodic or\nantiperiodic boundary conditions. For these special cases, the model is solved\nexactly by a Bethe ansatz, allowing for an exact calculation of the charge\npersistent current. In particular we show that the charge stiffness in the\nspecial case of spin-independent fluxes is insensitive to the presence of the\nmagnetic impurity/quantum dot."
    },
    {
        "anchor": "Experimental Progress on Layered Topological Semimetals: We review recent experimental progresses on layered topological materials,\nmainly focusing on transitional metal dichalcogenides with various lattice\ntypes including 1T, Td and 1T' structural phases. Their electronic quantum\nstates are interestingly rich, and many appear to be topological nontrivial,\nsuch as Dirac/Weyl semimetallic phase in multilayers and quantum spin hall\ninsulator phase in monolayers. The content covers recent major advances from\nmaterial synthesis, basic characterizations, angle-resolved photoemission\nspectroscopy measurements, transport and optical responses. Following those, we\noutlook the exciting future possibilities enabled by the marriage of\ntopological physics and two dimensional van der Waals layered heterostructures.",
        "positive": "Quantum transport theory of anomalous electric, thermoelectric, and\n  thermal Hall effects in ferromagnets: The mechanism of the anomalous Hall transport phenomena, if it is of the\nintrinsic or extrinsic origin, has been controversial. We present a unified\ntheory of them for ferromagnetic metals with dilute impurities at the zero\ntemperature, in terms of a quantum transport theory with the self-consistent\nT-matrix approximation. With the Fermi energy E_F and the spin-orbit\ninteraction energy E_{SO} being fixed (E_F > E_{SO}), three regimes are found\nas a function of the scattering rate \\hbar/\\tau. (i) In the superclean case\n\\hbar/\\tau < u_{imp} E_{SO}D, the skew scattering from the vertex correction\ndominates the anomalous Hall conductivity \\sigma_{xy}, where u_{imp} is the\nimpurity potential strength and D is the density of states. With increasing\n\\hbar/\\tau, this extrinsic skew-scattering contribution rapidly decays. (ii) In\nthe moderately dirty regime u_{imp}E_{SO}D < \\hbar/\\tau < E_{SO}, \\sigma_{xy}\nis dominated by the intrinsic dissipationless Berry-phase contribution, which\nis resonantly enhanced to the order of e^2/\\hbar when an accidental degeneracy\nof band dispersions around the Fermi level is lifted by the spin-orbit\ninteraction. (iii) Further increasing \\hbar/\\tau, a\n\\sigma_{xy}\\propto\\sigma_{xx}^{1.6} scaling appears, which has been verified by\nrecent experiments. The themal and thermoelectric Hall conductivities are also\ndiscussed."
    },
    {
        "anchor": "Edge states in a two-dimensional non-symmorphic semimetal: Dirac materials have unique transport properties, partly due to the presence\nof surface states. A new type of Dirac materials, protected by non-symmorphic\nsymmetries was recently proposed by Young and Kane [1]. By breaking of time\nreversal or inversion symmetry one can split the Dirac cones into Weyl nodes.\nThe later are characterized by local Chern numbers, that makes them\ntwo-dimensional analogs of Weyl semimetals. We find that the formation of the\nWeyl nodes is accompanied by an emergence of one-dimensional surface states,\nsimilar to Fermi arcs in Weyl semimetals and edge states in two-dimensional\ngraphene. We explore these states for a quasi-one-dimensional non-symmorphic\nribbon. The type and strength of applied deformation control the location and\nWeyl nodes and their composition. This determines the properties of emerging\nedge states. The sensitivity of these edge states to the external deformations\nmakes non-symmorphic materials potentially useful as a new type of\nelectromechanical sensors.",
        "positive": "Thermal frequency noise in low oscillation amplitude Dynamic Scanning\n  Force Microscopy: Thermal fluctuation of the cantilever position sets a fundamental limit for\nthe precision of any Scanning Force Microscope. In the present work we analyse\nhow these fluctuations limit the determination of the resonance frequency of\nthe tip-sample system. The basic principles of frequency detection in Dynamic\nScanning Force Microscopy are revised and the precise response of a typical\nfrequency detection unit to thermal fluctuation of the cantilever is analysed\nin detail. A general relation for thermal frequency noise is found as a\nfunction of measurement bandwidth and cantilever oscillation. For large\noscillation amplitude and low bandwidth, this relation converges to the result\nknown from the literature, while for low oscillation amplitude and large\nbandwidth we find that the thermal frequency noise is equal to the width of the\nresonance curve and therefore stays finite, contrary to what is predicted by\nthe relation known so far. The results presented in this work fundamentally\ndetermine the ultimate limits of Dynamic Scanning Force Microscopy."
    },
    {
        "anchor": "Visualizing electron correlation by means of ab-initio scanning\n  tunneling spectroscopy images of single molecules: Scanning tunneling microscopy (STM) has been a fundamental tool to\ncharacterize many-body effects in condensed matter systems, from extended\nsolids to quantum dots. STM of molecules decoupled from the supporting\nconductive substrate has the potential to extend STM characterization of many\nbody effects to the molecular world as well. In this article, we describe a\nmany-body tunneling theory for molecules decoupled from the STM substrate, and\nwe report on the use of standard quantum chemical methods to calculate the\nquantities necessary to provide the 'correlated' STM molecular image. The\ndeveloped approach has been applied to eighteen different molecules, to explore\nthe effects of their chemical nature and of their substituents, as well as to\nverify the possible contribution by transition metal centers. Whereas the bulk\nof calculations have been performed with CISD because of the computational\ncost, some tests have been also performed with the more accurate CCSD method to\nquantify the importance of the computational level on many-body STM images. We\nhave found that correlation induces a remarkable squeezing of the images, and\nthat correlated images are not derived from Hartree-Fock HOMO or LUMO alone,\nbut include contributions from other orbitals as well. Although correlation\neffects are too small to be resolved by present STM experiments for the studied\nmolecules, our results provide hints for seeking out other species with larger,\nand possibly experimentally detectable, correlation effects.",
        "positive": "Scanning-gate microscopy of semiconductor nanostructures: an overview: This paper presents an overview of scanning-gate microscopy applied to the\nimaging of electron transport through buried semiconductor nanostructures.\nAfter a brief description of the technique and of its possible artifacts, we\ngive a summary of some of its most instructive achievements found in the\nliterature and we present an updated review of our own research. It focuses on\nthe imaging of GaInAs-based quantum rings both in the low magnetic field\nAharonov-Bohm regime and in the high-field quantum Hall regime. In all of the\ngiven examples, we emphasize how a local-probe approach is able to shed new, or\ncomplementary, light on transport phenomena which are usually studied by means\nof macroscopic conductance measurements."
    },
    {
        "anchor": "Room-temperature exciton-polaritons with two-dimensional WS2: Two-dimensional transition metal dichalcogenides exhibit strong optical\ntransitions with significant potential for optoelectronic devices. In\nparticular they are suited for cavity quantum electrodynamics in which strong\ncoupling leads to polariton formation as a root to realisation of inversionless\nlasing, polariton condensationand superfluidity. Demonstrations of such\nstrongly correlated phenomena to date have often relied on cryogenic\ntemperatures, high excitation densities and were frequently impaired by strong\nmaterial disorder. At room-temperature, experiments approaching the strong\ncoupling regime with transition metal dichalcogenides have been reported, but\nwell resolved exciton-polaritons have yet to be achieved. Here we report a\nstudy of monolayer WS$_2$ coupled to an open Fabry-Perot cavity at\nroom-temperature, in which polariton eigenstates are unambiguously displayed.\nIn-situ tunability of the cavity length results in a maximal Rabi splitting of\n$\\hbar \\Omega_{\\rm{Rabi}} = 70$ meV, exceeding the exciton linewidth. Our data\nare well described by a transfer matrix model appropriate for the large\nlinewidth regime. This work provides a platform towards observing strongly\ncorrelated polariton phenomena in compact photonic devices for ambient\ntemperature applications.",
        "positive": "Green's functions of quasi-one-dimensional layered systems and their\n  application to Josephson junctions: We develop Green's function formalism to describe continuous multi-layered\nquasi-one-dimensional setups described by piece-wise constant single-particle\nHamiltonians. The Hamiltonians of the individual layers are assumed to be\nquadratic polynomials in the momentum operator with matrix-valued\n(multichannel) coefficients. This, in particular, allows one to study transport\nin heterostructures consisting of multichannel conducting, superconducting, or\ninsulating components with band structures of arbitrary complexity. We find a\ngeneral expression for the single-particle Green's function of the combined\nsetup in terms of the bulk (translationally invariant) Green's functions of its\nconstituents. Furthermore, we provide the expression for the global density of\nstates of the combined system and establish the bound state equation in terms\nof bulk Green's functions. We apply our formalism to investigate the spectrum\nand current-phase relations in ordinary and topological Josephson junctions,\nadditionally showing how to account for the effects of static disorder and\nlocal Coulomb interaction."
    },
    {
        "anchor": "Spin dynamics in a strongly driven system: very slow Rabi oscillations: We consider joint effects of tunneling and spin-orbit coupling on driven by\nelectric field spin dynamics in a double quantum dot with a multi-level\nresonance scenario. We demonstrate that tunneling plays the crucial role in the\nformation of the Rabi-like spin-flip transitions. In contrast to the linear\nbehavior for weak electric fields, the spin flip rate becomes much smaller than\nexpected for the two-level model and shows oscillating dependence on the\ndriving field amplitude in stronger fields. In addition, the full spin flip is\nvery difficult to achieve in a multi-level resonant system. These two effects\nhave a similarity with the Zeno effect of slowing down the dynamics of an\nobservable by its measurement. As a result, spin manipulation by electric field\nbecomes much less efficient than expected.",
        "positive": "Magnetoresistance oscillations in multilayer systems - triple quantum\n  wells: Magnetoresistance of two-dimensional electron systems with several occupied\nsubbands oscillates owing to periodic modulation of the probability of\nintersubband transitions by the quantizing magnetic field. In addition to\nprevious investigations of these magneto-intersubband (MIS) oscillations in\ntwo-subband systems, we report on both experimental and theoretical studies of\nsuch a phenomenon in three-subband systems realized in triple quantum wells. We\nshow that the presence of more than two subbands leads to a qualitatively\ndifferent MIS oscillation picture, described as a superposition of several\noscillating contributions. Under a continuous microwave irradiation, the\nmagnetoresistance of triple-well systems exhibits an interference of MIS\noscillations and microwaveinduced resistance oscillations. The theory\nexplaining these phenomena is presented in the general form, valid for an\narbitrary number of subbands. A comparison of theory and experiment allows us\nto extract temperature dependence of quantum lifetime of electrons and to\nconfirm the applicability of the inelastic mechanism of microwave\nphotoresistance for the description of magnetotransport in multilayer systems."
    },
    {
        "anchor": "Coherence Window in the dynamics of Quantum Nanomagnets: Decoherence in many solid-state systems is anomalously high, frustrating\nefforts to make solid-state qubits. We show that in nanomagnetic insulators in\nlarge transverse fields, there can be a fairly narrow field region in which\nboth phonon and nuclear spin-mediated decoherence are drastically reduced. As\nexamples we calculate decoherence rates for the $Fe$-8 nanomolecule, for $Ni$\nparticles, and for $Ho$ ions in $LiHo_xY_{1-z}F_4$. The reduction in the\ndecoherence, compared to low field rates, can exceed 6 orders of magnitude. The\nresults also give limitations on the observability of macroscopic coherence\neffects in magnetic systems.",
        "positive": "Domain-wall induced large magnetoresistance effects at zero applied\n  field in ballistic nanocontacts: We determine magnetoresistance effects in stable and clean permalloy\nnanocontacts of variable cross-section, fabricated by UHV deposition and\nin-situ electromigration. To ascertain the magnetoresistance (MR) effects\noriginating from a magnetic domain wall, we measure the resistance values with\nand without such a wall at zero applied field. In the ballistic transport\nregime, the MR ratio reaches up to 50% and exhibits a previously unobserved\nsign change. Our results can be reproduced by recent atomistic calculations for\ndifferent atomic configurations of the nanocontact, highlighting the importance\nof the detailed atomic arrangement for the MR effect."
    },
    {
        "anchor": "Positive and negative Coulomb drag in vertically integrated\n  one-dimensional quantum wires: Electron interactions in and between wires become increasingly complex and\nimportant as circuits are scaled to nanometre sizes, or employ\nreduced-dimensional conductors like carbon nanotubes, nanowires and gated high\nmobility 2D electron systems. This is because the screening of the long-range\nCoulomb potential of individual carriers is weakened in these systems, which\ncan lead to phenomenon such as Coulomb drag: a current in one wire induces a\nvoltage in a second wire through Coulomb interactions alone. Previous\nexperiments have observed electron drag in wires separated by a soft\nelectrostatic barrier $\\gtrsim$ 80 nm. Here, we measure both positive and\nnegative drag between adjacent vertical quantum wires that are separated by\n$\\sim$ 15 nm and have independent contacts, which allows their electron\ndensities to be tuned independently. We map out the drag signal versus the\nnumber of electron subbands occupied in each wire, and interpret the results in\nterms of momentum-transfer and charge-fluctuation induced transport models. For\nwires of significantly different subband occupancies, the positive drag effect\ncan be as large as 25%.",
        "positive": "Josephson effect in Graphene SNS Junction with a Single Localized Defect: Imperfections change essentially the electronic transport properties of\ngraphene. Motivated by a recent experiment reporting on the possible\napplication of graphene as junctions, we study transport properties in\ngraphene-based junctions with single localized defect. We solve the\nDirac-Bogoliubov-de-Gennes equation with a single localized defect\nsuperconductor-normal(graphene)-superconductor (SNS) junction. We consider the\nproperties of tunneling conductance and Josephson current through an undoped\nstrip of graphene with heavily doped s-wave superconducting electrodes in the\ndirty limit. We find that spectrum of Andreev bound states are modified in the\npresence of single localized defect in the bulk and the minimum tunneling\nconductance remains the same. The Josephson junction exhibits sign\noscillations."
    },
    {
        "anchor": "Nonequilibrium dephasing in Coulomb blockade quantum dots: We present a theory of zero-bias anomalies and dephasing rates for a\nCoulomb-blockaded quantum dot, driven out of equilibrium by coupling to voltage\nbiased source and drain leads. We interpret our results in terms of the\nstatistics of voltage fluctuations in the system.",
        "positive": "Soliton defects and topological $4\u03c0$-periodic superconductivity from\n  an orbital magnetic field effect in edge Josephson junctions: Recently, much research has been dedicated to understanding topological\nsuperconductivity and Majorana zero modes induced by a magnetic field in hybrid\nproximity structures. This paper proposes a realization of topological\nsuperconductivity in a short Josephson junction at an edge of a 2D topological\ninsulator subject to a perpendicular magnetic field. The magnetic field effect\nis entirely orbital, coming from a gradient of the order parameter phase at the\nedge, which results in a soliton defect at the junction with a pair of gapless\nAndreev bound states. The latter are reducible to Majorana zero modes by a\nunitary rotation and protected by a chiral symmetry. Furthermore, both ground\nstate and excitations are quasiperiodic in the magnetic flux enclosed in the\njunction, with the period equal to the double flux quantum $2\\Phi_0 = h/e$.\nThis behaviour follows from the gauge invariance of the $4\\pi$ - phase\nperiodicity of the Majorana states and manifests itself as $2\\Phi_0$ - spaced\nmagnetic oscillations of the critical current. Another proposed observable is a\npersistent current occurring in the absence of an external phase bias. Beside\nthe oscillations, it shows a sign reversal prompted by the neutral Majorana\nzero modes. These findings offer the possibility to access topological\nsuperconductivity through low-field dc magnetotransport measurements."
    },
    {
        "anchor": "Theory of Coherent Optical Control of Exciton Spin Dynamics in a\n  Semiconductor Quantum Dot: We use the spin-polarized excitons in a single quantum dot to design optical\ncontrols for basic operations in quantum computing. We examine the ultrafast\nnonlinear optical processes required and use the coherent nonlinear optical\nresponses to deduce if such processes are physically reasonable. The importance\nand construction of an entangled state of polarized exciton states in a single\nquantum dot is explained. We put our proposal in perspective with respect to a\nnumber of theoretical suggestions of utilizing the semiconductor quantum dots.",
        "positive": "Giant anisotropic magnetoresistance and planar Hall effect in the Dirac\n  semimetal Cd3As2: Anisotropic magnetoresistance is the change tendency of resistance of a\nmaterial on the mutual orientation of the electric current and the external\nmagnetic field. Here, we report experimental observations in the Dirac\nsemimetal Cd3As2 of giant anisotropic magnetoresistance and its transverse\nversion, called the planar Hall effect. The relative anisotropic\nmagnetoresistance is negative and up to -68% at 2 K and 10 T. The high\nanisotropy and the minus sign in this isotropic and nonmagnetic material are\nattributed to a field-dependent current along the magnetic field, which may be\ninduced by the Berry curvature of the band structure. This observation not only\nreveals unusual physical phenomena in Weyl and Dirac semimetals, but also finds\nadditional transport signatures of Weyl and Dirac fermions other than negative\nmagnetoresistance."
    },
    {
        "anchor": "Microscopic Theory of a Quantum Hall Ising Nematic: Domain Walls and\n  Disorder: We study the the interplay between spontaneously broken valley symmetry and\nspatial disorder in multivalley semiconductors in the quantum Hall regime. In\ncases where valleys have anisotropic electron dispersion a previous\nlong-wavelength analysis [Phys. Rev. B 82, 035428 (2010)] identified two new\nphases exhibiting the QHE. The first is the quantum Hall Ising nematic (QHIN),\na phase with long-range orientational order manifested in macroscopic transport\nanisotropies. The second is the quantum Hall random-field paramagnet (QHRFPM)\nthat emerges when the Ising ordering is disrupted by quenched disorder,\ncharacterized by a domain structure with a distinctive response to a valley\nsymmetry-breaking strain field. Here we provide a more detailed microscopic\nanalysis of the QHIN, which allows us to (i) estimate its Ising ordering\ntemperature; (ii) study its domain-wall excitations, which play a central role\nin determining its properties; and (iii) analyze its response to quenched\ndisorder from impurity scattering, which gives an estimate for domain size in\nthe descendant QHRFPM. Our results are directly applicable to AlAs\nheterostructures, although their qualitative aspects inform other ferromagnetic\nQH systems, such as Si(111) heterostructures and bilayer graphene with trigonal\nwarping.",
        "positive": "Nonadiabatic Nonlinear Optics and Quantum Geometry -- Application to the\n  Twisted Schwinger Effect: We study the tunneling mechanism of nonlinear optical processes in solids\ninduced by strong coherent laser fields. The theory is based on an extension of\nthe Landau-Zener model with nonadiabatic geometric effects. In addition to the\nrectification effect known previously, we find two effects, namely perfect\ntunneling and counterdiabaticity at fast sweep speed. We apply this theory to\nthe twisted Schwinger effect, i.e., nonadiabatic pair production of particles\nby rotating electric fields, and find a nonperturbative generation mechanism of\nthe opto-valley polarization and photo-current in Dirac and Weyl fermions."
    },
    {
        "anchor": "Massive Dirac fermions and Hofstadter butterfly in a van der Waals\n  heterostructure: Van der Waals heterostructures comprise a new class of artificial materials\nformed by stacking atomically-thin planar crystals. Here, we demonstrate band\nstructure engineering of a van der Waals heterostructure composed of a\nmonolayer graphene flake coupled to a rotationally-aligned hexagonal boron\nnitride substrate. The spatially-varying interlayer atomic registry results\nboth in a local breaking of the carbon sublattice symmetry and a long-range\nmoir\\'e superlattice potential in the graphene. This interplay between short-\nand long-wavelength effects results in a band structure described by isolated\nsuperlattice minibands and an unexpectedly large band gap at charge neutrality,\nboth of which can be tuned by varying the interlayer alignment.\nMagnetocapacitance measurements reveal previously unobserved fractional quantum\nHall states reflecting the massive Dirac dispersion that results from broken\nsublattice symmetry. At ultra-high fields, integer conductance plateaus are\nobserved at non-integer filling factors due to the emergence of the Hofstadter\nbutterfly in a symmetry-broken Landau level.",
        "positive": "Time-Resolved Mass Sensing of a Molecular Adsorbate Nonuniformly\n  Distributed Along a Nanomechnical String: We show that the particular distribution of mass deposited on the surface of\na nanomechanical resonator can be estimated by tracking the evolution of the\ndevice's resonance frequencies during the process of desorption. The technique,\nwhich relies on analytical models we have developed for the multimodal response\nof the system, enables mass sensing at much higher levels of accuracy than is\ntypically achieved with a single frequency-shift measurement and no rigorous\nknowledge of the mass profile. We report on a series of demonstration\nexperiments, in which the explosive molecule\n1,3,5-trinitroperhydro-1,3,5-triazine (RDX) is vapor deposited along the length\nof a silicon nitride nanostring to create a dense, random covering of RDX\ncrystallites on the surface. In some cases, the deposition is biased to produce\ndistributions with a slight excess or deficit of mass at the string midpoint.\nThe added mass is then allowed to sublimate away under vacuum conditions, with\nthe device returning to its original state over about 4 h (and the resonance\nfrequencies, measured via optical interferometry, relaxing back to their\npre-mass-deposition values). Our claim is that the detailed time trace of\nobserved frequency shifts is rich in information---not only about the quantity\nof RDX initially deposited but also about its spatial arrangement along the\nnanostring. The data also reveal that sublimation in this case follows a\nnontrivial rate law, consistent with mass loss occurring at the exposed surface\narea of the RDX crystallites."
    },
    {
        "anchor": "One-dimensional Weak Localization of Electrons in a Single InAs Nanowire: We report on low temperature (2-30K) electron transport and magneto-transport\nmeasurements of a chemically synthesized InAs nanowire. Both the temperature,\nT, and transverse magnetic field dependences of the nanowire conductance are\nconsistent with the functional forms predicted in one-dimensional (1D) weak\nlocalization theory. By fitting the magneto-conductance data to theory, the\nphase coherence length of electrons is determined to be tens of nanometers with\na T-1/3 dependence. Moreover, as the electron density is increased by a gate\nvoltage, the magneto-conductance shows a possible signature of suppression of\nweak localization in multiple 1D subbands.",
        "positive": "Persistent currents in diffusive metallic cavities: Large values and\n  anomalous scaling with disorder: The effect of disorder on confined metallic cavities with an Aharonov-Bohm\nflux line is addressed. We find that, even deep in the diffusive regime, large\nvalues of persistent currents may arise for a wide variety of geometries. We\npresent numerical results supporting an anomalous scaling law of the average\ntypical current $< I_{typ}>$ with the strength of disorder $w$, $< I_{typ}>\n\\sim w^{- \\gamma}$ with $\\gamma < 2$. This is contrasted with previously\nreported results obtained for cylindrical samples where a scaling $< I_{typ}>\n\\sim w^{-2}$ has been found. Possible links to, up to date, unexplained\nexperimental data are finally discussed."
    },
    {
        "anchor": "Time-resolved second harmonic generation study of buried semiconductor\n  heterointerfaces using soliton-induced transparency: The transient second harmonic generation and linear optical reflectivity\nsignals measured simultaneously in reflection from GaAs/GaSb/InAs and GaAs/GaSb\nheterostructures revealed a new mechanism for creating self-induced\ntransparency in narrow bandgap semiconductors at low temperatures, which is\nbased on the dual-frequency electro-optic soliton propagation. This allows the\nultrafast carrier dynamics at buried semiconductor heterointerfaces to be\nstudied.",
        "positive": "External magnetic fields enhance capture of magnetic nanoparticles\n  flowing through molded microfluidic channels by ferromagnetic nanostructures: Magnetic nanoparticles (MNPs) have many applications which require MNPs to be\ncaptured and immobilized for their manipulation and sensing. For example, MNP\nsensors based on detecting changes to the ferromagnetic resonances of an\nantidot nanostructure exhibit better performance when the nanoparticles are\ncaptured within the antidot inclusions. This study investigates the influence\nof microfluidics upon the capture of MNPs by four geometries of antidot array\nnanostructures hollowed into 30 nm-thick Permalloy films. The nanostructures\nwere exposed to a dispersion of 130 nm MNP clusters which passed through PDMS\nmicrofluidic channels with a 400 {\\mu}m circular cross-section fabricated from\nwire molds. With the microfluidic flow of MNPs, the capture efficiency - the\nratio between the number of nanoparticles captured inside of the antidot\ninclusions to the number outside the inclusions - decreased for all four\ngeometries compared to previous results introducing the particles via droplets\non the film surface. This indicates that most MNPs were passing over the\nnanostructures, since there were no significant magnetophoretic forces acting\nupon the particles. However, when a static magnetic field is applied, the\nmagnetophoretic forces generated by the nanostructure are stronger and the\ncapture efficiencies are significantly higher than those obtained using\ndroplets. In particular, circular antidots demonstrated the highest capture\nefficiency among the four geometries of almost 83.1% when the magnetic field is\nparallel to the film plane. In a magnetic field perpendicular to the film, the\ncircle antidots again show the highest capture efficiency of about 77%. These\nresults suggest that the proportion of nanoparticles captured inside antidot\ninclusions is highest under a parallel magnetic field. Clearly, the geometry of\nthe nanostructure has a strong influence on the capture of MNPs."
    },
    {
        "anchor": "Ground state of an exciton in a three-dimensional parabolic quantum dot:\n  convergent perturbative calculation: Working in the effective-mass approximation, we apply a powerful convergent\nperturbative technique of Turbiner's to the calculation of the ground state\nenergy and the wave function of an exciton confined to a three-dimensional\nparabolic quantum dot. Unlike the usual Rayleigh-Schrodinger perturbation\ntheory, Turbiner's approach works well even in the regime of strong coupling\nand does not require the knowledge of the full solution to the undisturbed\nproblem. The second-order convergent calculation presented below is in\nexcellent agreement with the results of exact numerical simulations for a wide\nrange of system's confinement parameters.",
        "positive": "Quantum spin Hall effect induced by electric field in silicene: We investigate the transport properties in a zigzag silicene nanoribbon in\nthe presence of an external electric field. The staggered sublattice potential\nand two kinds of Rashba spin-orbit couplings can be induced by the external\nelectric field due to the buckled structure of the silicene. A bulk gap is\nopened by the staggered potential and gapless edge states appear in the gap by\ntuning the two kinds of Rashba spin-orbit couplings properly. Furthermore, the\ngapless edge states are spin-filtered and are insensitive to the non-magnetic\ndisorder. These results prove that the quantum spin Hall effect can be induced\nby an external electric field in silicene, which may have certain practical\nsignificance in applications for future spintronics device."
    },
    {
        "anchor": "Microscopic theory of ionic motion in solids: Drag and diffusion of mobile ions in solids are of interest for both purely\ntheoretical and applied scientific communities. This article proposes a\ntheoretical description of ion drag in solids that can be used to estimate\nionic conductivities in crystals, and forms a basis for the rational design of\nsolid electrolyte materials. Starting with a general solid-state Hamiltonian,\nwe employ the non-equilibrium path integral formalism to develop a microscopic\ntheory of ionic transport in solids in the presence of thermal fluctuations. As\nrequired by the fluctuation-dissipation theorem, we obtain a relation between\nthe variance of the random force and friction. Because of the crystalline\nnature of the system, however, the two quantities are tensorial. We use the\ndrag tensor to write down the formula for ionic mobility, determined by the\npotential profile generated by the crystal's ions.",
        "positive": "Observing Atomic Collapse Resonances in Artificial Nuclei on Graphene: Relativistic quantum mechanics predicts that when the charge of a superheavy\natomic nucleus surpasses a certain threshold, the resulting strong Coulomb\nfield causes an unusual atomic collapse state; this state exhibits an electron\nwave function component that falls toward the nucleus, as well as a positron\ncomponent that escapes to infinity. In graphene, where charge carriers behave\nas massless relativistic particles, it has been predicted that highly charged\nimpurities should exhibit resonances corresponding to these atomic collapse\nstates. We have observed the formation of such resonances around artificial\nnuclei (clusters of charged calcium dimers) fabricated on gated graphene\ndevices via atomic manipulation with a scanning tunneling microscope. The\nenergy and spatial dependence of the atomic collapse state measured with\nscanning tunneling microscopy revealed unexpected behavior when occupied by\nelectrons."
    },
    {
        "anchor": "Emergence of charge density waves and a pseudogap in single-layer TiTe2: Two-dimensional materials constitute a promising platform for developing\nnanoscale devices and systems. Their physical properties can be very different\nfrom those of the corresponding three-dimensional materials because of extreme\nquantum confinement and dimensional reduction. Here we report a study of\nTiTe$_2$ from the single-layer to the bulk limit. Using angle-resolved\nphotoemission spectroscopy and scanning tunneling microscopy and spectroscopy,\nwe observed the emergence of a (2 x 2) charge density wave order in\nsingle-layer TiTe$_2$ with a transition temperature of 92 $\\pm$ 3 K. Also\nobserved was a pseudogap of about 28 meV at the Fermi level at 4.2 K.\nSurprisingly, no charge density wave transitions were observed in 2- and\nmulti-layer TiTe$_2$, despite the quasi-two-dimensional nature of the material\nin the bulk. The unique charge density wave phenomenon in the single layer\nraises intriguing questions that challenge the prevailing thinking about the\nmechanisms of charge density wave formation.",
        "positive": "On the ground state of fractional quantum Hall effect: The paper has bene withdrawn by the author."
    },
    {
        "anchor": "Anomalous Conductance Oscillations and Half-Metallicity in Atomic Ag-O\n  Chains: Using spin density functional theory we study the electronic and magnetic\nproperties of atomically thin, suspended chains containing silver and oxygen\natoms in an alternating sequence. Chains longer than 4 atoms develop a\nhalf-metallic ground state implying fully spin polarized charge carriers. The\nconductances of the chains exhibit weak even-odd oscillations around an\nanomalously low value of 0.1G_0 (G_0 = 2e^2h) which coincide with the averaged\nexperimental conductance in the long chain limit. The unusual conductance\nproperties are explained in terms of a resonating-chain model which takes the\nreflection probability and phase-shift of a single bulk-chain interface as the\nonly input. The model also explains the conductance oscillations for other\nmetallic chains.",
        "positive": "Two-dimensional extremely short optical pulses in silicene with random\n  electric fields: We investigate an influence of the random external electric field on the 2D\nextremely short optical pulses propagation in the silicene. The random electric\nfield is perpendicular to the silicene plane. An effective equation has the\nform of a wave equation with saturating nonlinearity. We analyze the\ndependences of the electromagnetic field intensity on the parameters of a\nproblem."
    },
    {
        "anchor": "Current to frequency conversion in a Josephson circuit: The voltage oscillations which occur in an ideally current-biased Josephson\njunction, were proposed to make a current standard for metrology. We\ndemonstrate similar oscillations in a more complex Josephson circuit derived\nfrom the Cooper pair box: the quantronium. When a constant current I is\ninjected in the gate capacitor of this device, oscillations develop at the\nfrequency fB=I/2e, with e the electron charge. We detect these oscillations\nthrough the sidebands induced at multiples of fB in the spectrum of a microwave\nsignal reflected on the circuit, up to currents I exceeding 100 pA. We discuss\nthe potential interest of this current to frequency conversion experiment for\nmetrology.",
        "positive": "Semiclassical Approach to Chaotic Quantum Transport: We describe a semiclassical method to calculate universal transport\nproperties of chaotic cavities. While the energy-averaged conductance turns out\ngoverned by pairs of entrance-to-exit trajectories, the conductance variance,\nshot noise and other related quantities require trajectory quadruplets; simple\ndiagrammatic rules allow to find the contributions of these pairs and\nquadruplets. Both pure symmetry classes and the crossover due to an external\nmagnetic field are considered."
    },
    {
        "anchor": "Nonlinear optical properties in a nanoring: Quantum size and\n  Aharonov-Bohm effect: We have performed calculations of nonlinear optical absorption and nonlinear\noptical rectification of an exciton in a nanoring in the presence of the\nmagnetic flux. Our results show that one can control properties of nonlinear\noptical absorption and nonlinear optical rectification of a nanoring by tuning\nouter and inner radius. In addition, we also find that nonlinear optical\nproperties of a nanoring can be modulated by the magnetic flux through\nnanoring.",
        "positive": "Higher-Order Topological Instanton Tunneling Oscillation: We propose a new type of instanton interference effect in two-dimensional\nhigher-order topological insulators. The intercorner tunneling consists of the\ninstanton and the anti-instanton pairs that travel through the boundary of the\nhigher-order topological insulator. The Berry phase difference between the\ninstanton pairs causes the interference of the tunneling. This topological\neffect leads to the gate-tunable oscillation of the energy splitting between\nthe corner states, where the oscillatory nodes signal the perfect suppression\nof the tunneling. We suggest this phenomenon as a unique feature of the\ntopological corner states that differentiate from trivial bound states. In the\nview of experimental realization, we exemplify twisted bilayer graphene, as a\npromising candidate of a two-dimensional higher-order topological insulator.\nThe oscillation can be readily observed through the transport experiment that\nwe propose. Thus, our work provides a feasible route to identify higher-order\ntopological materials."
    },
    {
        "anchor": "Moir\u00e9-enabled topological superconductivity: The search for artificial topological superconductivity has been limited by\nthe stringent conditions required for its emergence. As exemplified by the\nrecent discoveries of various correlated electronic states in twisted van der\nWaals materials, moir\\'e patterns can act as a powerful knob to create\nartificial electronic structures. Here, we demonstrate that a moir\\'e pattern\nbetween a van der Waals superconductor and a monolayer ferromagnet creates a\nperiodic potential modulation that enables the realization of a topological\nsuperconducting state that would not be accessible in the absence of the\nmoir\\'e. The magnetic moir\\'e pattern gives rise to Yu-Shiba-Rusinov minibands\nand periodic modulation of the Majorana edge modes that we detect using\nlow-temperature scanning tunneling microscopy (STM) and spectroscopy (STS).\nMoir\\'e patterns and, more broadly, periodic potential modulations are powerful\ntools to overcome the conventional constrains for realizing and controlling\ntopological superconductivity.",
        "positive": "Directional Roll-up of Nanomembranes Mediated by Wrinkling: We investigate the relaxation of rectangular wrinkled thin films\nintrinsically containing an initial strain gradient. A preferential rolling\ndirection, depending on wrinkle geometry and strain gradient, is theoretically\npredicted and experimentally verified. In contrast to typical rolled-up\nnanomembranes, which bend perpendicular to the longer edge of rectangular\npatterns, we find a regime where rolling parallel to the long edge of the\nwrinkled film is favorable. A non-uniform radius of the rolled-up film is well\nreproduced by elasticity theory and simulations of the film relaxation using a\nfinite element method."
    },
    {
        "anchor": "Heating of a two-dimensional electron gas by the electric field of a\n  surface acoustic wave: The heating of a two-dimensional electron gas by an rf electric field\ngenerated by a surface acoustic wave, which can be described by an electron\ntemperature $T_e$, has been investigated. It is shown that the energy balance\nof the electron gas is determined by electron scattering by the piezoelectric\npotential of the acoustic phonons with $T_e$ determined from measurements at\nfrequencies $f$= 30 and 150 MHz. The experimental curves of the energy loss $Q$\nversus $T_e$ at different SAW frequencies depend on the value of $\\omega\n\\bar{\\tau}_{\\epsilon}$, compared to 1, where $ \\bar {\\tau}_{\\epsilon}$ is the\nrelaxation time of the average electron energy. Theoretical calculations of the\nheating of a two-dimensional electron gas by the electric field of the surface\nacoustic wave are presented for the case of thermal electrons ($\\Delta T \\ll\nT$). The calculations show that for the same energy losses $Q$ the degree of\nheating of the two-dimensional electrons (i.e., the ratio $T_e/T$) for $\\omega\n\\bar{\\tau}_{\\epsilon}>1$ ($f$= 150 MHz) is less than for $\\omega\n\\bar{\\tau}_{\\epsilon}<1$ ($f$=30 MHz). Experimental results confirming this\ncalculation are presented.",
        "positive": "Orthogonal Cherenkov sound in spin-orbit coupled systems: Conventionally the Cherenkov sound is governed by {\\it orbital} degrees of\nfreedom and is excited by {\\it supersonic} particles. Additionally, it usually\nhas a {\\it forward} nature with a conic geometry known as the Cherenkov cone\nwhose axis is oriented {\\it along} the {\\it supersonic} particle motion. Here\nwe predict Cherenkov sound of a unique nature entirely resulting from the\nelectronic {\\it spin} degree of freedom and demonstrate a fundamentally\ndistinct Cherenkov effect originating from essentially {\\it subsonic} electrons\nin two-dimensional gases with both Bychkov-Rashba and Dresselhaus spin-orbit\ninteractions. Specifically, we show that the axis of the conventional {\\it\nforward} Cherenkov cone gets a nontrivial {\\it quarter-turn} and at the same\ntime the sound distribution strongly localizes around this rotated axis being\nnow {\\it orthogonal} to the {\\it subsonic} particle motion. Apart from its\nfundamentally appealing nature, the orthogonal Cherenkov sound could have\napplications in planar semiconductor technology combining spin and acoustic\nphenomena to develop, {\\it e.g.}, acoustic amplifiers or sound sources with a\nflexible spin dependent orientation of the sound propagation."
    },
    {
        "anchor": "Averaged equation for energy diffusion on a graph reveals bifurcation\n  diagram and thermally assisted reversal times in spin-torque driven\n  nanomagnets: Driving nanomagnets by spin-polarized currents offers exciting prospects in\nmagnetoelectronics, but the response of the magnets to such currents remains\npoorly understood. We show that an averaged equation describing the diffusion\nof energy on a graph captures the low-damping dynamics of these systems. From\nthis equation we obtain the bifurcation diagram of the magnets, including the\ncritical currents to induce stable precessional states and magnetization\nswitching, as well as the mean times of thermally assisted magnetization\nreversal in situations where the standard reaction rate theory of Kramers is no\nlonger valid. These results match experimental observations and give a\ntheoretical basis for a N\\'eel-Brown-type formula with an effective energy\nbarrier for the reversal times.",
        "positive": "Electron transport in multi-terminal molecular device: The electron transport properties of a four-terminal molecular device are\ncomputed within the framework of density functional theory and non-equilibrium\nKeldysh theory. The additional two terminals lead to new properties, including\na pronounced negative differential resistance not present in a two-terminal\nsetup, and a pseudo-gating effect. In general, quantum interference between the\nfour terminals and the central molecule leads to a complex non-linear behavior,\ndependent on the alignment of individual molecular states under bias and their\ncoupling to the leads."
    },
    {
        "anchor": "Spin Wave Electromagnetic Nano-Antenna Enabled by Tripartite\n  Phonon-Magnon-Photon Coupling: We investigate tripartite coupling between phonons, magnons and photons in a\nperiodic array of elliptical magnetostrictive nanomagnets delineated on a\npiezoelectric substrate to form a two-dimensional two-phase multiferroic\ncrystal. A surface acoustic wave (phonons) of 5 - 35 GHz frequency launched\ninto the substrate causes the magnetizations of the nanomagnets to precess at\nthe frequency of the wave, giving rise to spin waves (magnons). The spin waves,\nin turn, radiate electromagnetic waves (photons) into the surrounding space at\nthe surface acoustic wave frequency. Here, the phonons couple into magnons,\nwhich then couple into photons. This tripartite phonon-magnon-photon coupling\nis exploited to implement an extreme sub-wavelength electromagnetic antenna\nwhose measured radiation efficiency and antenna gain exceed the theoretical\nlimits for traditional antennas by more than two orders of magnitude at some\nfrequencies. Micro-magnetic simulations are in excellent agreement with\nexperimental observations and provide insight into the spin wave modes that\ncouple into radiating electromagnetic modes to implement the antenna.",
        "positive": "Carrier-carrier scattering and negative dynamic conductivity in pumped\n  graphene: We theoretically examine the effect of carrier-carrier scattering processes\n(electron-hole and electron-electron) on the intraband radiation absorption and\ntheir contribution to the net dynamic conductivity in optically or electrically\npumped graphene. We demonstrate that the radiation absorption assisted by the\ncarrier-carrier scattering can be stronger than the Drude absorption due to the\ncarrier scattering on disorder. Since the intraband absorption of radiation\neffectively competes with its interband amplification, this can substantially\naffect the conditions of the negative dynamic conductivity in the pumped\ngraphene and, hence, the interband terahertz and infrared lasing. We find the\nthreshold values of the frequency and quasi-Fermi energy of nonequilibrium\ncarriers corresponding to the onset of negative dynamic conductivity. The\nobtained results show that the effect of carrier-carrier scattering shifts the\nthreshold frequency of the radiation amplification in pumped graphene to higher\nvalues. In particular, the negative dynamic conductivity is attainable at the\nfrequencies above 6 THz in graphene on SiO2 substrates at room temperature. The\nthreshold frequency can be decreased to markedly lower values in graphene\nstructures with high-k substrates due to screening of the carrier-carrier\nscattering, particularly at lower temperatures."
    },
    {
        "anchor": "Nonlinear cotunneling through an artificial molecule: We study electron transport through a system of two lateral quantum dots\ncoupled in series. We consider the case of weak coupling to the leads and a\nbias point in the Coulomb blockade. After a generalized Schrieffer-Wolf\ntransformation, cotunneling through this system is described using methods from\nlowest-order perturbation theory. We study the system for arbitrary bias\nvoltages below the Coulomb energy. We observe a rich, non-monotonic behavior of\nthe stationary current depending on the internal degrees of freedom. In\nparticular, it turns out that at fixed transport voltage, the current through\nthe system is largest at weak-to-intermediate inter-dot coupling.",
        "positive": "Scanning Gate Spectroscopy of transport across a Quantum Hall\n  Nano-Island: We explore transport across an ultra-small Quantum Hall Island (QHI) formed\nby closed quan- tum Hall edge states and connected to propagating edge channels\nthrough tunnel barriers. Scanning gate microscopy and scanning gate\nspectroscopy are used to first localize and then study a single QHI near a\nquantum point contact. The presence of Coulomb diamonds in the spectroscopy\ncon- firms that Coulomb blockade governs transport across the QHI. Varying the\nmicroscope tip bias as well as current bias across the device, we uncover the\nQHI discrete energy spectrum arising from electronic confinement and we extract\nestimates of the gradient of the confining potential and of the edge state\nvelocity."
    },
    {
        "anchor": "Brownian motion of massive skyrmions forced by spin polarized currents: We report on the thermal effects on the motion of current-driven massive\nmagnetic skyrmions. The reduced equation for the motion of skyrmion has the\nform of a stochastic generalized Thiele's equation. We propose an ansatz for\nthe magnetization texture of a non-rigid single skyrmion that depends linearly\nwith the velocity. By utilizing this ansatz it is is found that the mass of\nskyrmion is closely related to intrinsic skyrmion parameters, such as Gilbert\ndamping, skyrmion-charge and dissipative force. We have found an exact\nexpression for the average drift velocity as well as the mean-square velocity\nof the skyrmion. The longitudinal and transverse mobility of skyrmions for\nsmall spin-velocity of electrons is also determined and found to be independent\nof the skyrmion mass.",
        "positive": "Methodology for bus layout for topological quantum error correcting\n  codes: Most quantum computing architectures can be realized as two-dimensional\nlattices of qubits that interact with each other. We take transmon qubits and\ntransmission line resonators as promising candidates for qubits and couplers;\nwe use them as basic building elements of a quantum code. We then propose a\nsimple framework to determine the optimal experimental layout to realize\nquantum codes. We show that this engineering optimization problem can be\nreduced to the solution of standard binary linear programs. While solving such\nprograms is a NP-hard problem, we propose a way to find scalable optimal\narchitectures that require solving the linear program for a restricted number\nof qubits and couplers. We apply our methods to two celebrated quantum codes,\nnamely the surface code and the Fibonacci code."
    },
    {
        "anchor": "Interacting resonant level coupled to a Luttinger liquid: Universality\n  of thermodynamic properties: We investigate a model of a single resonant level coupled to the edge of a\nquantum wire in the Luttinger liquid phase or to the middle of a chiral\nLuttinger liquid via both tunneling and a contact interaction. Utilizing the\nYuval-Anderson approach, we map this model onto a classical 1D Coulomb gas in\nwhich all the details of both the interactions in the lead and the level-lead\ninteraction enter only through the corresponding Fermi-edge singularity\nexponent, which we explicitly evaluate using the Bethe ansatz solution for a\nparticular model of the lead. Thus the population, dynamical capacitance and\nlevel entropy are universal in the sense of being equal for models with\ninteractions differing in magnitude and even in sign. We demonstrate this to\nhold quantitatively using density matrix renormalization group calculations.\nSince the Coulomb gas description is of the single channel Kondo type, we infer\nthat the universality we found implies that Luttinger liquid physics has no\nqualitative effect on these properties, in contrast with perturbative results.",
        "positive": "Dissipative Edge Transport in Disordered Axion Insulator Films: We investigate the role of disorder in the edge transport of axion insulator\nfilms. We predict by first-principles calculations that even-number-layer\nMnBi$_2$Te$_4$ have gapped helical edge states. The random potential will\ndramatically modify the edge spectral function to become gapless. However, such\ngapless helical state here is fundamentally different from that in quantum spin\nHall insulator or topological Anderson insulator. We further study the edge\ntransport in this system by Landauer-B\\\"{u}ttiker formalism, and find such\ngapless edge state is dissipative and not immune to backscattering, which would\nexplain the dissipative nonlocal transport in the axion insulator state\nobserved in six septuple layer MnBi$_2$Te$_4$ experimentally. Several transport\nexperiments are proposed to verify our theory on the dissipative helical edge\nchannels. In particular, the longitudinal resistance can be greatly reduced by\nadding an extra floating probe even if it is not used. These results will\nfacilitate the observsation of long-sought topological magnetoelectric effect\nin axion insulators."
    },
    {
        "anchor": "Orbital and spin Kondo effects in a double quantum dot: Motivated by recent experiments, in which the Kondo effect has been observed\nfor the first time in a double quantum-dot structure, we study electron\ntransport through a system consisting of two ultrasmall, capacitively-coupled\ndots with large level spacing and charging energy. Due to strong interdot\nCoulomb correlations, the Kondo effect has two possible sources, the spin and\norbital degeneracies, and it is maximized when both occur simultaneously. The\nlarge number of tunable parameters allows a range of manipulations of the Kondo\nphysics -- in particular, the Kondo effect in each dot is sensitive to changes\nin the state of the other dot. For a thorough account of the system dynamics,\nthe linear and nonlinear conductance is calculated in perturbative and\nnon-perturbative approaches. In addition, the temperature dependence of the\nresonant peak heights is evaluated in the framework of a renormalization group\nanalysis.",
        "positive": "Mechanical control of heat conductivity in microscopic models of\n  dielectrics: We discuss a possibility to control a heat conductivity in simple\none-dimensional models of dielectrics by means of external mechanical loads. To\nillustrate such possibilities we consider first a well-studied chain with\ndegenerate double-well potential of the interparticle interaction. Contrary to\nprevious studies, we consider varying length of the chain with fixed number of\nparticles. Number of possible energetically degenerate ground states strongly\ndepends on the overall length of the chain, or, in other terms, on average\nlength of the link between neighboring particles. These degenerate states\ncorrespond to mechanical equilibrium, therefore one can say that the transition\nbetween them mimics to some extent a process of plastic deformation. We\ndemonstrate that such modification of the chain length can lead to quite\nprofound (almost five-fold) reduction of the heat conduction coefficient. Even\nmore profound effect is revealed for a model with single-well non-convex\npotential. It is demonstrated that in certain range of constant external\nforcing this model becomes \"effectively\"\\ double-well, and has a multitude of\npossible states of equilibrium for the same value of the external load. Thus,\nthe heat conduction coefficient can be reduced by two orders of magnitude. We\nsuggest a mechanical model of a chain with periodic double-well potential,\nwhich allows control over the heat conduction. The models considered may be\nuseful for description of heat transport in biological macromolecules and for\ncontrol of the heat transport in microsystems."
    },
    {
        "anchor": "Disappearence of the Aharonov-Bohm Effect for Interacting Electrons in a\n  ZnO Quantum Ring: The electronic states and optical transitions of a ZnO quantum ring\ncontaining few interacting electrons in an applied magnetic field are found to\nbe very different from those in a conventional semiconductor system, such as a\nGaAs ring. The strong Zeeman and Coulomb interaction of the ZnO system, exert a\nprofound influence on the electron states and on the optical properties of the\nring. In particular, our results indicate that the Aharonov-Bohm (AB) effect in\na ZnO quantum ring strongly depends on the electron number. In fact, for two\nelectrons in the ZnO ring, the AB oscillations become aperiodic, while for\nthree electrons (interacting) the AB oscillations completely disappear.\nTherefore, unlike in conventional quantum ring topology, here the AB effect\n(and the resulting persistent current) can be controlled by varying the\nelectron number.",
        "positive": "Interferometry and dynamics of a transmon-type qubit in front of a\n  mirror: We theoretically describe the stationary regime and coherent dynamics of a\ncapacitively shunted transmon-type qubit which is placed in front of a mirror.\nThe considered qubit is irradiated by two signals: pump (dressing) and probe.\nBy changing amplitudes and frequencies of these signals we study the system\nbehaviour. The main tool of our theoretical analysis is solving of the Lindblad\nequation. We also consider Lindblad superoperators in charge and energy bases\nand compare the results. Theoretically obtained occupation probability is\nrelated to the experimentally measured value. This study helps to understand\nbetter the properties of qubit-mirror system and gives new insights about the\nunderlying physical processes."
    },
    {
        "anchor": "Valley entanglement of excitons in monolayers of transition-metal\n  dichalcogenides: We show that excitons and free carriers in K and K' valleys of transition\nmetal dichalcogenide monolayers can be entangled with respect to their valley\ndegree of freedom by absorbing linearly polarized single photons. This effect\ndoes not require any interaction between K and K' excitons in contrast to\nconventional mechanisms of entanglement that are mediated by coupling between\nquantum systems (e.g.~entanglement of photons in nonlinear optical\ninteractions). The valley entanglement of excitons and free carriers can be\nverified by measuring the polarization of their photoluminescence or\nfluctuations of the photocurrent under an applied in-plane DC bias.",
        "positive": "Direct link between Coulomb blockade and shot noise in a quantum\n  coherent structure: We analyze the current-voltage characteristic of a quantum conduction channel\ncoupled to an electromagnetic environment of arbitrary frequency-dependent\nimpedance. In the weak blockade regime the correction to the ohmic behavior is\ndirectly related to the channel current fluctuations vanishing at perfect\ntransmission in the same way as shot noise. This relation can be generalized to\ndescribe the environmental Coulomb blockade in a generic mesoscopic conductor\ncoupled to an external impedance, as the response of the latter to the current\nfluctuations in the former."
    },
    {
        "anchor": "An interacting adiabatic quantum motor: We present a field theoretic treatment of an adiabatic quantum motor. We\nexplicitly discuss a motor termed Thouless motor which is based on a Thouless\npump operating in reverse. When a sliding periodic potential is considered as\nthe motor degree of freedom, a bias voltage applied to the electron channel\nsets the motor in motion. We investigate a Thouless motor whose electron\nchannel is modeled as a Luttinger liquid. Interactions increase the gap opened\nby the periodic potential. For an infinite Luttinger liquid the coupling\ninduced friction is enhanced by electron-electron interactions. When the LL is\nultimately coupled to Fermi liquid reservoirs, the dissipation reduces to its\nvalue for a noninteracting electron system for a constant motor velocity. Our\nresults can also be applied to a motor based on a nanomagnet coupled to a\nquantum spin Hall edge.",
        "positive": "Spontaneous Spin Coherence in n-GaAs Produced by Ferromagnetic Proximity\n  Polarization: We find that photoexcited electrons in an n-GaAs epilayer rapidly (< 50 ps)\nspin-polarize due to the proximity of an epitaxial ferromagnetic metal.\nComparison between MnAs/GaAs and Fe/GaAs structures reveals that this coherent\nspin polarization is aligned antiparallel and parallel to their magnetizations,\nrespectively. In addition, the GaAs nuclear spins are dynamically polarized\nwith a sign determined by the spontaneous electron spin orientation. In\nFe/GaAs, competition between nuclear hyperfine and applied magnetic fields\nresults in complete quenching of electron spin precession."
    },
    {
        "anchor": "Current-voltage characteristics of tunable\n  ferromagnet-silicon-ferromagnet channels in the spin blockade regime: The steady current-voltage characteristics of ferromagnet-silicon-ferromagnet\nchannels with tunable emitter and collector polarizations are investigated in\nthe presence of spin blockade generalizing the model developed by Pershin Yu V\nand Di Ventra M (2008 {\\it Phys. Rev.} B {\\bf 77} 073301). The dependence of\nthe critical current on both collector and emitter polarizations is obtained\nanalytically. It is found that the current amplitude in the channel can be\neffectively tuned by varying the difference between the collector and emitter\nferromagnet polarizations which allows to perform the magnetic manipulation of\nthe electrical current in wide class of both n- and p-doped, low- and\nhigh-Ohmic semiconductor channels coupled to ferromagnetic leads.",
        "positive": "Nonlinear Optical Susceptibilities and Linear Absorption in Phosphorene\n  Nanoribbons: Ab initio study: Using Density Functional Theory (DFT) method we compute linear optical\nabsorption spectra and nonlinear optical susceptibilities of hydrogen\npassivated armchair and zigzag Phosphorous Nanoribbons (aPNR and zPNR) as well\nas \\alpha-phase phosphorous monolayer. We observe that: (a) Crystallographic\ndirection has a strong effect on the band edge absorption which causes optical\nanisotropy as well as a red shift of absorption spectra by increasing the\nnanoribbon width. (b) The absorption values are in the order of $10^{5}\ncm^{-1}$ which are similar to the experimentally measured values. (c) There is\ntwo orders of magnitude enhancement of the 2nd order nonlinear optical\nsusceptibility, $\\chi^{(2)}$, in nanoribbons which emanates from breaking the\ncentro-symmetric structure of a monolayer phosphorene by hydrogen surface\nterminations. (d) Chief among our results is that the 3rd order susceptibility,\n$\\chi^{(3)}$, for phosphorene monolayer and nanoribbons are about $~10^{-13}$\nesu ($~10^{-21} \\frac{m^{2}}{V^{2}}$) which are in close agreement with\nexperimentally reported values as well as a recently calculated value based on\nsemi-analytic method. This strongly supports reliability of our method in\ncalculating nonlinear optical susceptibilities of phosphorene and in general\nother nanostructures. Enhanced 2nd order optical nonlinearity in phosphorene\npromises better second harmonic and frequency difference (THz) generation for\nphotonics applications."
    },
    {
        "anchor": "Sub-Kelvin Lateral Thermal Transport in Diffusive Graphene: In this work, we report on hot carrier diffusion in graphene across large\nenough length scales that the carriers are not thermalized across the crystal.\nThe carriers are injected into graphene at one site and their thermal transport\nis studied as a function of applied power and distance from the heating source,\nup to tens of micrometers away. Superconducting contacts prevent out-diffusion\nof hot carriers to isolate the electron-phonon coupling as the sole channel for\nthermal relaxation. As local thermometers, we use the amplitude of the\nUniversal Conductance Fluctuations, which varies monotonically as a function of\ntemperature. By measuring the electron temperature simultaneously along the\nlength we observe a thermal gradient which results from the competition between\nelectron-phonon cooling and lateral heat flow.",
        "positive": "Elastic Spin Hall effect in Mechanical Graphene: We show that spin-orbit interaction and elastic spin-Hall effect can exist in\na classical mechanical system consisting of a two-dimensional honeycomb lattice\nof masses and springs. The band structure shows the presence of splitting at K\npoint induced by the difference of longitudinal and transverse elastic\nconstant, and this splitting can be regarded as an effective Dresselhaus-type\nspin-orbit coupling. Interestingly, as an initial displacement away from the\nequilibrium is applied, the time evolution simulation shows that waves of\ndifferent spin polarization propagates along different directions at the Gamma\nand K point, which is characteristic of spin-Hall effect. Several cases for\nspin-Hall effect are also discussed."
    },
    {
        "anchor": "Thermovoltage and heat dissipation in a triangle quantum dot junction: We numerically investigate the thermoelectric properties of a triangle\nquantum dot connected to metallic electrodes using the non-equilibrium Green's\nfunction method in the Anderson model. Exploiting the equation of motion method\nin the Coulomb-blockade regime, the thermovoltage, thermocurrent and heat\ndissipation are calculated. Results show that the thermovoltage and\nthermocurrent have nonlinear behavior, and the magnitude and sign of them can\nbe controlled with site energy and coupling strength of quantum dots. Moreover,\nwe find that the heat current is nonlinear and asymmetric respect to the sign\nof bias voltage for all of the site energies of quantum dots. Analyses show\nthat the heat current can be positive or negative for all of the site energies\nand becomes zero for the nonzero voltages. These results can be useful to\ndetermine the performance of the nanoscale electronic devices to control the\nheat dissipations.",
        "positive": "Drude weight and optical conductivity of a two-dimensional heavy-hole\n  gas with $k$-cubic spin-orbit interactions: We present detailed theoretical study on zero-frequency Drude weight and\noptical conductivity of a two-dimensional heavy-hole gas(2DHG) with $k$-cubic\nRashba and Dresselhaus spin-orbit interactions. The presence of $k$-cubic\nspin-orbit couplings strongly modifies the Drude weight in comparison to the\nelectron gas with $k$-linear spin-orbit couplings. For large hole density and\nstrong $k$-cubic spin-orbit couplings, the density dependence of Drude weight\ndeviates from the linear behavior. We establish a relation between optical\nconductivity and the Berry connection. Unlike two-dimensional electron gas with\n$k$-linear spin-orbit couplings, we explicitly show that the optical\nconductivity does not vanish even for equal strength of the two spin-orbit\ncouplings. We attribute this fact to the non-zero Berry phase for equal\nstrength of $k$-cubic spin-orbit couplings. The least photon energy needed to\nset in the optical transition in hole gas is one order of magnitude smaller\nthan that of electron gas. Types of two van Hove singularities appear in the\noptical spectrum are also discussed."
    },
    {
        "anchor": "Electron transfer through a single barrier inside a molecule: from\n  strong to weak coupling: In all theoretical treatments of electron transport through single molecules\nbetween two metal electrodes, a clear distinction has to be made between a\ncoherent transport regime with a strong coupling throughout the junction and a\nCoulomb blockade regime in which the molecule is only weakly coupled to both\nleads. The former case where the tunnelling barrier is considered to be\ndelocalized across the system can be well described with common mean-field\ntechniques based on density functional theory (DFT), while the latter case with\nits two distinct barriers localized at the interfaces usually requires a\nmultideterminant description. There is a third scenario with just one barrier\nlocalized inside the molecule which we investigate here using a variety of\nquantum-chemical methods by studying partial charge shifts in biphenyl radical\nions induced by an electric field at different angles to modulate the coupling\nand thereby the barrier within the $\\pi$-system. We find steps rounded off at\nthe edges in the charge versus field curves for weak and intermediate coupling,\nwhose accurate description requires a correct treatment of both exchange and\ndynamical correlation effects is essential. We establish that DFT standard\nfunctionals fail to reproduce this feature, while a long range corrected hybrid\nfunctional fares much better, which makes it a reasonable choice for a proper\nDFT-based transport description of such single barrier systems",
        "positive": "Breakdown of the integer and fractional quantum Hall states in a quantum\n  point contact: The integer and fractional quantum Hall states are known to break down at\nhigh dc bias, exhibiting deviation from the ideal incompressible behavior. We\nmeasure breakdown of the \\nu = 2, 3, 4, 5 integer and the \\nu = 4/3 and 5/3\nfractional states in a quantum point contact (QPC) of lithographic width ~600\nnm. Dependence of the critical current on magnetic field, QPC gate voltage, and\nQPC width are presented. Of particular interest, the critical current of the\n4/3 and 5/3 fractional states shows the opposite dependence on QPC width\ncompared to the integer states. This previously unobserved result is not\nexplained by current theories of breakdown."
    },
    {
        "anchor": "New Class of Non-Abelian Spin-Singlet Quantum Hall States: We present a new class of non-abelian spin-singlet quantum Hall states,\ngeneralizing Halperin's abelian spin-singlet states and the Read-Rezayi\nnon-abelian quantum Hall states for spin-polarized electrons. We label the\nstates by (k,M) with M odd (even) for fermionic (bosonic) states, and find a\nfilling fraction $\\nu=2k/(2kM+3)$. The states with M=0 are bosonic spin-singlet\nstates characterized by an SU(3)_k symmetry. We explain how an effective\nLandau-Ginzburg theory for the SU(3)_2 state can be constructed. In general,\nthe quasi-particles over these new quantum Hall states carry spin, fractional\ncharge and non-abelian quantum statistics.",
        "positive": "Exact results for the Kondo screening cloud of two helical liquids: We analyze the screening of a magnetic quantum dot with spin 1/2 coupled to\ntwo helical liquids. Interestingly, we find two qualitatively different sets of\nToulouse points, i.e., nontrivial parameters for which we can solve the two\nchannel Kondo model exactly. This enables us to calculate the temperature and\nvoltage dependent Kondo screening cloud, which develops oscillations for an\napplied spin voltage $\\mu_s$. Such a spin voltage can be conveniently applied\nby a charge bias in a four-terminal helical liquid setup."
    },
    {
        "anchor": "Graphene field-effect transistor array with integrated electrolytic\n  gates scaled to 200 mm: Ten years have passed since the beginning of graphene research. In this\nperiod we have witnessed breakthroughs both in fundamental and applied\nresearch. However, the development of graphene devices for mass production has\nnot yet reached the same level of progress. The architecture of graphene\nfield-effect transistors (FET) has not significantly changed, and the\nintegration of devices at the wafer scale has generally not been sought.\nCurrently, whenever an electrolyte-gated FET (EGFET) is used, an external,\ncumbersome, out-of-plane gate electrode is required. Here, an alternative\narchitecture for graphene EGFET is presented. In this architecture, source,\ndrain, and gate are in the same plane, eliminating the need for an external\ngate electrode and the use of an additional reservoir to confine the\nelectrolyte inside the transistor active zone. This planar structure with an\nintegrated gate allows for wafer-scale fabrication of high-performance graphene\nEGFETs, with carrier mobility up to 1800 cm2 V-1 s-1. As a proof-of principle,\na chemical sensor was achieved. It is shown that the sensor can discriminate\nbetween saline solutions of different concentrations. The proposed architecture\nwill facilitate the mass production of graphene sensors, materializing the\npotential of previous achievements in fundamental and applied graphene\nresearch.",
        "positive": "Charge screening and carrier transport in AA-stacked bilayer graphene:\n  tuning via a perpendicular electric field: The static dielectric function in AA-stacked bilayer graphene (BLG),\nsubjected to an electric field applied perpendicular to layers, is calculated\nanalytically within the random phase approximation (RPA). This result is used\nto calculate the screened Coulomb interaction and the electrical conductivity.\nThe screened Coulomb interaction, which here can be tuned by the perpendicular\nelectric field, shows a power-law decay as $1/(\\gamma^{2}+V^2)$ at\nlong-distance limit where $V$ and $\\gamma$ are the electrical potential and the\ninter-layer hopping energy respectively, indicating that the Coulomb\ninteraction is suppressed at high perpendicular electric fields. Furthermore,\nOur results for the effect of the short-range and the long-range (Coulomb)\nscattering on the electrical conductivity show that the shot-range scattering\nyields a constant electrical conductivity which is not affected by the\nperpendicular electric filed. While the electrical conductivity limited by the\nCoulomb scattering is enhanced by the perpendicular electric field and\nincreases linearly in $V^2$ at small $V$ with a finite value at $V=0$,\nindicating that we can tune the electrical conductivity in AA-stacked BLG by\napplying a perpendicular electric field."
    },
    {
        "anchor": "Writable spin wave nanochannels in an artificial-spin-ice-mediated\n  ferromagnetic thin film: Magnonics, which employs spin-waves to transmit and process information, is a\npromising venue for low-power data processing. One of the major challenges is\nthe local control of the spin-wave propagation path. Here, we introduce the\nconcept of writable magnonics by taking advantage of the highly flexible\nreconfigurability and rewritability of artificial spin ice systems. Using\nmicromagnetic simulations, we show that globally switchable spin-wave\npropagation and the locally writable spin-wave nanochannels can be realized in\na ferromagnetic thin film underlying an artificial pinwheel spin ice. The\nrewritable magnonics enabled by reconfigurable spin wave nanochannels provides\na unique setting to design programmable magnonic circuits and logic devices for\nultra-low power applications.",
        "positive": "A Comprehensive Model of Nitrogen-Free Ordered Carbon Quantum Dots: We propose and demonstrate a novel range of models to accurately determine\nthe optical properties of nitrogen-free carbon quantum dots (CQDs) with ordered\ngraphene layered structures. We confirm the results of our models against the\nfull range of experimental results for CQDs available from an extensive review\nof the literature. The models can be equally applied to CQDs with varied sizes\nand with different oxygen content in the basal planes of the constituent\ngraphenic sheets. We demonstrate that the experimentally observed blue\nfluorescent emission of nitrogen-free CQDs can be associated with either small\noxidised areas on the periphery of the graphenic sheets, or with sub-nanometre\nnon-functionalised islands of sp2-hybridised carbon with high symmetry confined\nin the centres of oxidised graphene sheets. Larger and/or less symmetric\nnon-functionalised regions in the centre of functionalised graphene sheet are\nfound to be sources of green and even red fluorescent emission from\nnitrogen-free CQDs. We also demonstrate an approach to simplify the modelling\nof the discussed sp2-islands by substitution with equivalent strained\npolycyclic aromatic hydrocarbons. Additionally, we show that the bandgaps (and\nphotoluminescence) of CQDs are not dependent on either out-of-plane corrugation\nof the graphene sheet or the spacing between sp2-islands. Advantageously, our\nproposed models show that there is no need to involve light-emitting polycyclic\naromatic molecules (nanographenes) with arbitrary structures grafted to the\nparticle periphery to explain the plethora of optical phenomena observed for\nCQDs across the full range of experimental works."
    },
    {
        "anchor": "Backaction Dephasing by a Quantum Dot Detector: We derive an analytical expression for the backaction dephasing rate, which\ncharacterizes the disturbance induced by coupling with an environment\ncontaining a quantum dot detector (QDD). In this letter, we show that charge\nnoise induces backaction dephasing in an explicit form. In the linear transport\nregime through a QDD, this backaction dephasing induced by charge noise can be\nexplained as a relaxation by an inelastic electron-electron scattering in Fermi\nliquid theory. In the low bias voltage regime, the increase or decrease of\ndephasing rate depends on the QDD energy level, the linewidth functions, and\nhow to apply the bias voltage. Unlike quantum point contact, the dephasing rate\nwould be insensitive to the bias voltage in a high bias voltage regime because\nof the saturation of charge noise in a QDD.",
        "positive": "Collective Antenna Effects in the Terahertz and Infrared Response of\n  Highly Aligned Carbon Nanotube Arrays: We study macroscopically-aligned single-wall carbon nanotube arrays with\nuniform lengths via polarization-dependent terahertz and infrared transmission\nspectroscopy. Polarization anisotropy is extreme at frequencies less than\n$\\sim$3 THz with no sign of attenuation when the polarization is perpendicular\nto the alignment direction. The attenuation for both parallel and perpendicular\npolarizations increases with increasing frequency, exhibiting a pronounced and\nbroad peak around 10 THz in the parallel case. We model the electromagnetic\nresponse of the sample by taking into account both radiative scattering and\nabsorption losses. We show that our sample acts as an effective antenna due to\nthe high degree of alignment, exhibiting much larger radiative scattering than\nabsorption in the mid/far-infrared range. Our calculated attenuation spectrum\nclearly shows a non-Drude peak at $\\sim$10 THz in agreement with the\nexperiment."
    },
    {
        "anchor": "A state with negative binding energy induced by coherent transport in a\n  quantum wire: In a two-dimensional quantum wire in a perpendicular magnetic field with a\nsmooth embedded repulsive scattering potential we find in the multimode\nconductance resonances caused by bound states with negative binding energy.\nThese resonances are the counterexamples to well known dips in the conductance\nand evanescent states caused by quasi-bound states of attractive scattering\ncenters in the wire.",
        "positive": "Transport Processes in Metal-Insulator Granular Layers: Tunnel transport processes are considered in a square lattice of metallic\nnanogranules embedded into insulating host to model tunnel conduction in real\nmetal/insulator granular layers. Based on a simple model with three possible\ncharging states ($\\pm$, or 0) of a granule and three kinetic processes\n(creation or recombination of a $\\pm$ pair, and charge transfer) between\nneighbor granules, the mean-field kinetic theory is developed. It describes the\ninterplay between charging energy and temperature and between the applied\nelectric field and the Coulomb fields by the non-compensated charge density.\nThe resulting charge and current distributions are found to be essentially\ndifferent in the free area (FA), between the metallic contacts, or in the\ncontact areas (CA), beneath those contacts. Thus, the steady state dc transport\nis only compatible with zero charge density and ohmic resistivity in FA, but\ncharge accumulation and non-ohmic behavior are \\emph{necessary} for conduction\nover CA. The approximate analytic solutions are obtained for characteristic\nregimes (low or high charge density) of such conduction. The comparison is done\nwith the measurement data on tunnel transport in related experimental systems."
    },
    {
        "anchor": "Phonon drag thermopower and weak localization: Previous experimental work on a two-dimensional (2D) electron gas in a\nSi-on-sapphire device led to the conclusion that both conductivity and phonon\ndrag thermopower $S^g$ are affected to the same relative extent by weak\nlocalization. The present paper presents further experimental and theoretical\nresults on these transport coefficients for two very low mobility 2D electron\ngases in $\\delta-$doped GaAs/Ga$_x$Al$_{1-x}$As quantum wells. The experiments\nwere carried out in the temperature range 3-7K where phonon drag dominates the\nthermopower and, contrary to the previous work, the changes observed in the\nthermopower due to weak localization were found to be an order of magnitude\nless than those in the conductivity. A theoretical framework for phonon drag\nthermopower in 2D and 3D semiconductors is presented which accounts for this\ninsensitivity of $S^g$ to weak localization. It also provides transparent\nphysical explanations of many previous experimental and theoretical results.",
        "positive": "Experimental evidence for non-Abelian gauge potentials in twisted\n  graphene bilayers: The methods for realizing of non-Abelian gauge potentials have been proposed\nin many different systems in condensed matter1-5. The simplest realization\namong them may be in a graphene bilayer obtained by slightly relative rotation\nbetween the two layers4. Here we report the experimental evidence for\nnon-Abelian gauge potentials in twisted graphene bilayers by scanning\ntunnelling microscopy and spectroscopy. At a magic twisted angle, theta ~\n(1.11+/-0.05)deg, a pronounced sharp peak, which arises from the nondispersive\nflat bands at the charge neutrality point, are observed in the tunnelling\ndensity of states due to the action of the non-Abelian gauge fields4,6-8.\nMoreover, we observe confined electronic states in the twisted bilayer, as\nmanifested by regularly spaced tunnelling peaks with energy spacing detal E ~\nvF/D ~ 70 meV (here vF is the Fermi velocity of graphene and D is the period of\nthe Moire patterns). Our results direct demonstrate that the non-Abelian gauge\npotentials in twisted graphene bilayers confine low-energy electrons into a\ntriangular array of quantum dots following the modulation of the Moire\npatterns."
    },
    {
        "anchor": "Effects of Defects and Dephasing on Charge and Spin Currents in\n  Two-Dimensional Topological Insulators: Using the non-equilibrium Keldysh Green's function formalism, we investigate\nthe effect of defects on the electronic structure and transport properties of\ntwo-dimensional topological insulators (TI). We demonstrate how the spatial\nflow of charge changes between the topologically protected edge and bulk states\nand show that elastically and inelastically scattering defects that preserve\nthe time reversal symmetry of the TI lead to qualitatively different effects on\nthe TI's local electronic structure and its transport properties. Moreover, we\nshow that the recently predicted ability to create highly spin-polarized\ncurrents by breaking the time-reversal symmetry of the TI via magnetic defects\n[Phys. Rev. B 93, 081401 (2016)] is robust against the inclusion of a Rashba\nspin-orbit interaction and the effects of dephasing, and remains unaffected by\nchanges over a wide range of the TI's parameters. We discuss how the sign of\nthe induced spin currents changes under symmetry operations, such as reversal\nof bias and gate voltages, or spatial reflections. Finally, we show that the\ninsight into the interplay between topology and symmetry of the magnetic\ndefects can be employed for the creation of novel quantum phenomena, such as\nhighly localized magnetic fields inside the TI.",
        "positive": "Superconducting coplanar waveguide resonators for low temperature pulsed\n  electron spin resonance spectroscopy: We discuss the design and implementation of thin film superconducting\ncoplanar waveguide micro- resonators for pulsed ESR experiments. The\nperformance of the resonators with P doped Si epilayer samples is compared to\nwaveguide resonators under equivalent conditions. The high achievable filling\nfactor even for small sized samples and the relatively high Q-factor result in\na sensitivity that is superior to that of conventional waveguide resonators, in\nparticular to spins close to the sample surface. The peak microwave power is on\nthe order of a few microwatts, which is compatible with measurements at ultra\nlow temperatures. We also discuss the effect of the nonuniform microwave\nmagnetic field on the Hahn echo power dependence."
    },
    {
        "anchor": "Super-Andreev reflection and longitudinal shift of pseudospin-one\n  fermions: Novel fermions with a pseudospin-1 structure can be realized as emergent\nquasiparticles in condensed matter systems. Here, we investigate its unusual\nproperties during the Andreev reflection at a normal-metal/superconductor (NS)\ninterface. We show that distinct from the previously studied pseudospin-1/2 and\ntwo dimensional electron gas models, the pseudospin-1 fermions exhibit a\nstrongly enhanced Andreev reflection probability, and remarkably, can be\nfurther tuned to approach perfect Andreev reflection with unit efficiency for\nall incident angles, exhibiting a previously unknown {super-Andreev reflection\neffect}. The super-Andreev reflection leads to perfect transparency of the NS\ninterface that strongly promotes charge injection into the superconductor, and\ndirectly manifests as a differential conductance peak which can be readily\nprobed in experiment. Additionally, we find that sizable longitudinal shifts\nexist in the normal and Andreev reflections of pseudospin-1 fermions. Distinct\nfrom the pseudospin-1/2 case, the shift is always in the forward direction in\nthe subgap regime, regardless of whether the reflection is of retro- or\nspecular type.",
        "positive": "Visualization and Control of Single Electron Charging in Bilayer\n  Graphene Quantum Dots: Graphene p-n junctions provide an ideal platform for investigating novel\nbehavior at the boundary between electronics and optics that arise from\nmassless Dirac fermions, such as whispering gallery modes and Veselago lensing.\nBilayer graphene also hosts Dirac fermions, but they differ from single-layer\ngraphene charge carriers because they are massive, can be gapped by an applied\nperpendicular electric field, and have very different pseudospin selection\nrules across a p-n junction. Novel phenomena predicted for these massive Dirac\nfermions at p-n junctions include anti-Klein tunneling, oscillatory Zener\ntunneling, and electron cloaked states. Despite these predictions there has\nbeen little experimental focus on the microscopic spatial behavior of massive\nDirac fermions in the presence of p-n junctions. Here we report the\nexperimental manipulation and characterization of massive Dirac fermions within\nbilayer graphene quantum dots defined by circular p-n junctions through the use\nof scanning tunneling microscopy-based (STM) methods. Our p-n junctions are\ncreated via a flexible technique that enables realization of exposed quantum\ndots in bilayer graphene/hBN heterostructures. These quantum dots exhibit sharp\nspectroscopic resonances that disperse in energy as a function of applied gate\nvoltage. Spatial maps of these features show prominent concentric rings with\ndiameters that can be tuned by an electrostatic gate. This behavior is\nexplained by single-electron charging of localized states that arise from the\nquantum confinement of massive Dirac fermions within our exposed bilayer\ngraphene quantum dots."
    },
    {
        "anchor": "Odd-frequency superconducting pairing in junctions with Rashba\n  spin-orbit coupling: We consider normal-superconductor (NS) and\nsuperconductor-normal-superconductor (SNS) junctions based on one-dimensional\nnanowires with Rashba spin-orbit coupling and proximity-induced $s$-wave\nspin-singlet superconductivity and analytically demonstrate how both even- and\nodd-frequency and spin-singlet and -triplet superconducting pair correlations\nare always present. In particular, by using a fully quantum mechanical\nscattering approach, we show that Andreev reflection induces mixing of spatial\nparities at interfaces, thus being the unique process which generates\nodd-frequency pairing; on the other hand, both Andreev and normal reflections\ncontribute to even-frequency pairing. We further find that locally neither\nodd-frequency nor spin-triplet correlations are induced, but only\neven-frequency spin-singlet pairing. In the superconducting regions of NS\njunctions, the interface-induced amplitudes decay into the bulk, with the\nodd-frequency components being generally much larger than the even-frequency\ncomponents at low frequencies. The odd-frequency pairing also develops short\nand long-period oscillations due to the chemical potential and spin-orbit\ncoupling, respectively, leading to a visible beating feature in their\nmagnitudes. Moreover, we find that in short SNS junctions at $\\pi$-phase\ndifference and strong spin-orbit coupling, the odd-frequency spin-singlet and\n-triplet correlations strongly dominate with an alternating spatial pattern for\na large range of sub-gap frequencies.",
        "positive": "Measurement of the Spin Relaxation Time of Single Electrons in a Silicon\n  MOS-Based Quantum Dot: We report on measurements of the spin relaxation time T1 of individual\nelectron spins in the few electron regime of a Si/SiO2-based quantum dot (QD).\nEnergy-spectroscopy of the QD has been performed using a charge sensing\ntechnique. The spin relaxation times are subsequently measured in the\ntime-domain by a pump-and-probe method. For the QD that contains an unpaired\nspin, likely only a single electron, we find that T1 depends strongly on the\napplied magnetic field. Possible mechanisms leading to the observed spin\nrelaxation are discussed."
    },
    {
        "anchor": "Chern insulating state in laterally patterned semiconductor\n  heterostructures: Hexagonally patterned two-dimensional $p$-type semiconductor systems are\nquantum simulators of graphene with strong and highly tunable spin-orbit\ninteractions. We show that application of purely in-plane magnetic fields, in\ncombination with the crystallographic anisotropy present in low-symmetry\nsemiconductor interfaces, allows Chern insulating phases to emerge from an\noriginally topologically insulating state after a quantum phase transition.\nThese phases are characterized by pairs of co-propagating edge modes and Hall\nconductivities $\\sigma_{xy} = +\\frac{2 e^2}{h}, -\\frac{2 e^2}{h}$ in the\nabsence of Landau levels or cyclotron motion. With current lithographic\ntechnology, the Chern insulating transitions are predicted to occur in GaAs\nheterostructures at magnetic fields of $\\sim 5\\text{T}$.",
        "positive": "Coherent Josephson thermodynamic cycles: A superconductor/normal metal/superconductor Josephson junction is a coherent\nelectron system where the thermodynamic entropy depends on temperature and\nphase difference across the weak-link. Here, exploiting the phase-temperature\nthermodynamic diagram of a thermally isolated system, we argue that a cooling\neffect can be achieved when the phase drop across the junction is brought from\n0 to $\\pi$ in a iso-entropic process. We show that iso-entropic cooling can be\nenhanced with proper choice of geometrical and electrical parameters of the\njunction, i.e. by increasing the ratio between supercurrent and total junction\nvolume. We present extensive numerical calculations using quasi-classical Green\nfunction methods for a short junction and we compare them with analytical\nresults. Interestingly, we demonstrate that phase-coherent thermodynamic cycles\ncan be implemented by combining iso-entropic and iso-phasic processes acting on\nthe weak-link, thereby engineering the coherent version of thermal machines\nsuch as engines and cooling systems. We therefore evaluate their performances\nand the minimum temperature achievable in a cooling cycle."
    },
    {
        "anchor": "Linear response conductance and magneto-resistance of ferromagnetic\n  single-electron transistors: The current through ferromagnetic single-electron transistors (SET's) is\nconsidered. Using path integrals the linear response conductance is formulated\nas a function of the tunnel conductance vs. quantum conductance and the\ntemperature vs. Coulomb charging energy. The magneto-resistance of\nferromagnet-normal metal-ferromagnet (F-N-F) SET's is almost independent of the\nCoulomb charging energy and is only reduced when the transport dwell time is\nlonger than the spin-flip relaxation time. In all-ferromagnetic (F-F-F) SET's\nwith negligible spin-flip relaxation time the magneto-resistance is calculated\nanalytically at high temperatures and numerically at low temperatures. The\nF-F-F magneto-resistance is enhanced by higher order tunneling processes at low\ntemperatures in the 'off' state when the induced charges vanishes. In contrast,\nin the 'on' state near resonance the magneto-resistance ratio is a\nnon-monotonic function of the inverse temperature.",
        "positive": "Length-dependent thermal conductivity in suspended single-layer graphene: Graphene exhibits extraordinary electronic and mechanical properties, and\nextremely high thermal conductivity. Being a very stable atomically thick\nmembrane that can be suspended between two leads, graphene provides a perfect\ntest platform for studying thermal conductivity in two-dimensional systems,\nwhich is of primary importance for phonon transport in low-dimensional\nmaterials. Here we report experimental measurements and non-equilibrium\nmolecular dynamics simulations of thermal conduction in suspended single layer\ngraphene as a function of both temperature and sample length. Interestingly and\nin contrast to bulk materials, when temperature at 300K, thermal conductivity\nkeeps increasing and remains logarithmic divergence with sample length even for\nsample lengths much larger than the average phonon mean free path. This result\nis a consequence of the two-dimensional nature of phonons in graphene and\nprovides fundamental understanding into thermal transport in two-dimensional\nmaterials."
    },
    {
        "anchor": "CVD Synthesis of Small-Diameter Single Walled Carbon Nanotubes on\n  Silicon: A simple process for chemical vapor deposition of ultra SD single wall carbon\nnanotubes has been developed. In this process, an iron nitrate nonahydrate\nsolution in isopropyl alcohol with a concentration of 400 ug/mlit was used to\ncatalyze nanoparticles formation on an oxidized silicon wafer. The oxide on the\nsubstrate was made of a thick layer of wet oxide sandwiched between tow thin\nlayers of dry oxide. The process results in semiconducting single-walled carbon\nnanotubes (SWNTs) with diameter of less than 0.7nm and more than 1ev band gap\nenergy, which are amongst the smallest diameters of SWNTs ever reported.",
        "positive": "Giant optomechanical coupling and dephasing protection with cavity\n  exciton-polaritons: Electronic resonances can significantly enhance the photon-phonon coupling in\ncavity optomechanics, but are normally avoided due to absorption losses and\ndephasing by inhomogeneous broadening. We experimentally demonstrate that\nexciton-polaritons in semiconductor microcavities enable GHz optomechanics with\nsingle-particle resonant couplings reaching record values in the 10s of MHz\nrange. Moreover, this resonant enhancement is protected from inhomogeneous\nbroadening by the Rabi gap. Single-polariton non-linearities and the\noptomechanical strong-coupling regime become accessible in this platform."
    },
    {
        "anchor": "Low-energy sub-gap states in multi-channel Majorana wires: One-dimensional p-wave superconductors are known to harbor Majorana bound\nstates at their ends. Superconducting wires with a finite width W may have\nfermionic subgap states in addition to possible Majorana end states. While they\ndo not necessarily inhibit the use of Majorana end states for topological\ncomputation, these subgap states can obscure the identification of a\ntopological phase through a density-of-states measurement. We present two\nsimple models to describe low-energy fermionic subgap states. If the wire's\nwidth W is much smaller than the superconductor coherence length \\xi, the\nrelevant subgap states are localized near the ends of the wire and cluster near\nzero energy, whereas the lowest-energy subgap states are delocalized if $W\n\\gtrsim \\xi$. Notably, the energy of the lowest-lying fermionic subgap state\n(if present at all) has a maximum for W ~ \\xi.",
        "positive": "Tunneling conductance in strained graphene-based superconductor: Effect\n  of asymmetric Weyl-Dirac fermions: Based on the BTK theory, we investigate the tunneling conductance in a\nuniaxially strained graphene-based normal metal (NG)/ barrier\n(I)/superconductor (SG) junctions. In the present model, we assume that\ndepositing the conventional superconductor on the top of the uniaxially\nstrained graphene, normal graphene may turn to superconducting graphene with\nthe Cooper pairs formed by the asymmetric Weyl-Dirac electrons, the massless\nfermions with direction-dependent velocity. The highly asymmetrical velocity,\nvy/vx>>1, may be created by strain in the zigzag direction near the transition\npoint between gapless and gapped graphene. In the case of the highly\nasymmetrical velocity, we find that the Andreev reflection strongly depends on\nthe direction and the current perpendicular to the direction of strain can flow\nin the junction as if there was no barrier. Also, the current parallel to the\ndirection of strain anomalously oscillates as a function of the gate voltage\nwith very high frequency. Our predicted result is found as quite different from\nthe feature of the quasiparticle tunneling in the unstrained graphene-based\nNG/I/SG conventional junction. This is because of the presence of the\ndirection-dependent-velocity quasiparticles in the highly strained graphene\nsystem."
    },
    {
        "anchor": "Origin of nonlocal resistance in multiterminal graphene on\n  hexagonal-boron-nitride: Fermi surface edge currents rather than Fermi sea\n  topological valley currents: The recent observation [R. V. Gorbachev et al., Science {\\bf 346}, 448\n(2014)] of nonlocal resistance $R_\\mathrm{NL}$ near the Dirac point (DP) of\nmultiterminal graphene on aligned hexagonal boron nitride (G/hBN) has been\ninterpreted as the consequence of topological valley Hall currents carried by\nthe Fermi sea states just beneath the bulk gap $E_g$ induced by the inversion\nsymmetry breaking. However, the valley Hall conductivity $\\sigma^v_{xy}$,\nquantized inside $E_g$, is not directly measurable. Conversely, the\nLandauer-B\\\"{u}ttiker formula, as numerically exact approach to observable\nnonlocal transport quantities, yields $R_\\mathrm{NL} \\equiv 0$ for the same\nsimplistic Hamiltonian of gapped graphene that generates $\\sigma^v_{xy} \\neq\n0$. We combine ab initio with quantum transport calculations to demonstrate\nthat G/hBN wires with zigzag edges host dispersive edge states near the DP that\nare absent in theories based on the simplistic Hamiltonian. Although such edge\nstates exist also in isolated zigzag graphene wires, aligned hBN is required to\nmodify their energy-momentum dispersion and generate $R_\\mathrm{NL} \\neq 0$\nnear the DP persisting in the presence of edge disorder. Concurrently, the edge\nstates resolve the long-standing puzzle of why the highly insulating state of\nG/hBN is rarely observed. We conclude that the observed $R_\\mathrm{NL}$ is\nunrelated to Fermi sea topological valley currents conjectured for gapped Dirac\nspectra.",
        "positive": "Cavity Quantum Electrodynamics with a Single Quantum Dot Coupled to a\n  Photonic Molecule: We demonstrate the effects of cavity quantum electrodynamics for a quantum\ndot coupled to a photonic molecule, consisting of a pair of coupled photonic\ncrystal cavities. We show anti-crossing between the quantum dot and the two\nsuper-modes of the photonic molecule, signifying achievement of the strong\ncoupling regime. From the anti-crossing data, we estimate the contributions of\nboth mode-coupling and intrinsic detuning to the total detuning between the\nsuper-modes. Finally, we also show signatures of off-resonant cavity-cavity\ninteraction in the photonic molecule."
    },
    {
        "anchor": "Chiral magnetization textures stabilized by the Dzyaloshinskii-Moriya\n  interaction during spin-orbit torque switching: We study the effect of the Dzyaloshinskii-Moriya interaction (DMI) on\ncurrent-induced magnetic switching of a perpendicularly magnetized\nheavy-metal/ferromagnet/oxide trilayer both experimentally and through\nmicromagnetic simulations. We report the generation of stable helical\nmagnetization stripes for a sufficiently large DMI strength in the switching\nregion, giving rise to intermediate states in the magnetization confirming the\nessential role of the DMI on switching processes. We compare the simulation and\nexperimental results to a macrospin model, showing the need for a micromagnetic\napproach. The influence of the temperature on the switching is also discussed.",
        "positive": "Transport through a double barrier for interacting quasi one-dimensional\n  electrons in a Quantum Wire in the presence of a transverse magnetic field: We discuss the Luttinger Liquid behaviour of a semiconducting Quantum Wire.\nWe show that the measured value of the bulk critical exponent, $\\alpha_{bulk}$,\nfor the tunneling density of states can be easily calculated.\n  Then, the problem of the transport through a Quantum Dot formed by two\nQuantum Point Contacts along the Quantum Wire, weakly coupled to spinless\nTomonaga-Luttinger liquids is studied, including the action of a strong\ntransverse magnetic field $B$.\n  The known magnetic dependent peaks of the conductance, $G(B)$, in the\nballistic regime at a very low temperature, $T$, have to be reflected also in\nthe transport at higher $T$ and in different regimes. The temperature\ndependence of the maximum $G_{max}$ of the conductance peak, according to the\nCorrelated Sequential Tunneling theory, yields the power law $G_{max}\\propto\nT^{2\\alpha_{end}-1}$, with the critical exponent, $\\alpha_{end}$, strongly\nreduced by $B$.\n  This behaviour suggests the use of a similar device as a magnetic field\nmodulated transistor."
    },
    {
        "anchor": "Spin emitters beyond the point dipole approximation in nanomagnonic\n  cavities: Control over transition rates between spin states of emitters is crucial in a\nwide variety of fields ranging from quantum information science to the\nnanochemistry of free radicals. We present an approach to drive a both electric\nand magnetic dipole-forbidden transition of a spin emitter by placing it in a\nnanomagnonic cavity, requiring a description of both the spin emitter beyond\nthe point dipole approximation and the vacuum magnetic fields of the\nnanomagnonic cavity with a large spatial gradient over the volume of the spin\nemitter. We specifically study the SiV$^-$ defect in diamond, whose\nZeeman-split ground states comprise a logical qubit for solid-state quantum\ninformation processing, coupled to a magnetic nanoparticle serving as a model\nnanomagnonic cavity capable of concentrating microwave magnetic fields into\ndeeply subwavelength volumes. Through first principles modeling of the SiV$^-$\nspin orbitals, we calculate the spin transition densities of magnetic\ndipole-allowed and -forbidden transitions and calculate their coupling rates to\nvarious multipolar modes of the nanomagnonic cavity. We envision using such a\nframework for quantum state transduction and state preparation of spin qubits\nat GHz frequency scales.",
        "positive": "Relativistic suppression of Auger recombination in Weyl semimetals: Auger recombination (AR) being electron-hole annihilation with\nenergy-momentum transfer to another carrier is believed to speed up in\nmaterials with small band gap. We theoretically show that this rule is violated\nin gapless three-dimensional materials with ultra-relativistic electron-hole\ndispersion, Weyl semimetals (WSM). Namely, AR is prohibited by energy-momentum\nconservation laws in prototypical WSM with a single Weyl node, even in the\npresence of anisotropy and tilt. In real multi-node WSM, the geometric\ndissimilarity of nodal dispersions enables weak inter-node AR, which is further\nsuppressed by strong screening due to large number of nodes. While partial AR\nrates between the nodes of the same node group are mutually equal, the\ninter-group processes are non-reciprocal, so that one of groups is\ngeometrically protected from AR. Our calculations show that geometrical\nprotection can help prolonging AR lifetime by the two orders of magnitude, up\nto the level of nanoseconds."
    },
    {
        "anchor": "Skyrmion Qubits: Challenges For Future Quantum Computing Applications: Magnetic nano-skyrmions develop quantized helicity excitations, and the\nquantum tunneling between nano-skyrmions possessing distinct helicities is\nindicative of the quantum nature of these particles. Experimental methods\ncapable of non-destructively resolving the quantum aspects of topological spin\ntextures, their local dynamical response, and their functionality now promise\npractical device architectures for quantum operations. With abilities to\nmeasure, engineer, and control matter at the atomic level, nano-skyrmions\npresent opportunities to translate ideas into solid-state technologies.\nProof-of-concept devices will offer electrical control over the helicity,\nopening a promising new pathway towards functionalizing collective spin states\nfor the realization of a quantum computer based on skyrmions. This Perspective\naims to discuss developments and challenges in this new research avenue in\nquantum magnetism and quantum information.",
        "positive": "Dynamic response of an artificial square spin ice: Magnetization dynamics in an artificial square spin-ice lattice made of\nNi80Fe20 with magnetic field applied in the lattice plane is investigated by\nbroadband ferromagnetic resonance spectroscopy. The experimentally observed\ndispersion shows a rich spectrum of modes corresponding to different\nmagnetization states. These magnetization states are determined by exchange and\ndipolar interaction between individual islands, as is confirmed by a\nsemianalytical model. In the low field regime below 400 Oe a hysteretic\nbehavior in the mode spectrum is found. Micromagnetic simulations reveal that\nthe origin of the observed spectra is due to the initialization of different\nmagnetization states of individual nanomagnets. Our results indicate that it\nmight be possible to determine the spin-ice state by resonance experiments and\nare a first step towards the understanding of artificial geometrically\nfrustrated magnetic systems in the high-frequency regime."
    },
    {
        "anchor": "Photoinduced dynamics in quantum rings: We investigate the spin-dependent dynamical response of a semiconductor\nquantum ring with a spin orbit interaction (SOI) upon the application of a\nsingle and two linearly polarized, picosecond, asymmetric electromagnetic\npulses in the presence of a static magnetic flux. We find that the\npulse-generated electric dipole moment is spin dependent. It is also shown that\nthe SOI induces an extra SU(2) effective flux in addition to the static\nexternal magnetic flux which is reflected in an additional periodicity of the\nspin-dependent dipole moment. Furthermore, the pulses may induce a net\ndynamical charge currents (CC) and dynamical spin currents (SC) when the\nclockwise and anti-clockwise symmetry of the carrier is broken upon the pulse\napplication.",
        "positive": "Polaritonic and Excitonic Time Crystals based on TMDC strips in an\n  external periodic potential: We investigated the dynamics of Bose-Einstein condensates (BECs) under an\nexternal periodic potential. We consider two such systems, the first being made\nof exciton-polaritons in a nanoribbon of transition metal dichalcogenides\n(TMDCs), such as MoSe$_2$, embedded in a microcavity with a special curvature,\nwhich serves as the source of the external potential. The second, made of bare\nexcitons in a nanoribbon of twisted TMDC bilayer, which naturally creates a\nperiodic Moir\\'e potential that can be controlled by the angle of twist. We\nproved that such systems exhibit a Time Crystal (TC) phase. This was\ndemonstrated by the fact that the calculated BEC spatial density profile shows\na non-trivial two-point correlator that oscillates in time. These BECs density\nprofiles were calculated by solving the quantum Lindblad master equations for\nthe density matrix within the mean-field approximation. We then go beyond the\nusual mean-field approach, by adding a stochastic term to the master equation,\nwhich corresponds to quantum corrections, and we show that the TC phase is\nstill present."
    },
    {
        "anchor": "Lande-like formula for the g factors of hole-nanowire subband edges: We have analyzed theoretically the Zeeman splitting of hole-quantum-wire\nsubband edges. As is typical for any bound state, their g factor depends on\nboth an intrinsic g factor of the material and an additional contribution\narising from a finite bound-state orbital angular momentum. We discuss the\nquantum-confinement-induced interplay between bulk-material and orbital\neffects, which is nontrivial due to the presence of strong spin-orbit coupling.\nA compact analytical formula is provided that elucidates this interplay and can\nbe useful for predicting Zeeman splitting in generic hole-wire geometries.",
        "positive": "Density of states of a two-dimensional electron gas in a non-quantizing\n  magnetic field: We study local density of electron states of a two-dimentional conductor with\na smooth disorder potential in a non-quantizing magnetic field, which does not\ncause the standart de Haas-van Alphen oscillations. It is found, that despite\nthe influence of such ``classical'' magnetic field on the average electron\ndensity of states (DOS) is negligibly small, it does produce a significant\neffect on the DOS correlations. The corresponding correlation function exhibits\noscillations with the characteristic period of cyclotron quantum\n$\\hbar\\omega_c$."
    },
    {
        "anchor": "Interaction-induced corrections to conductance and thermopower in\n  quantum wires: We study transport properties of weakly interacting spinless electrons in\none-dimensional single channel quantum wires. The effects of interaction\nmanifest as three-particle collisions due to the severe constraints imposed by\nthe conservation laws on the two-body processes. We focus on short wires where\nthe effects of equilibration on the distribution function can be neglected and\ncollision integral can be treated in perturbation theory. We find that\ninteraction-induced corrections to conductance and thermopower rely on the\nscattering processes that change number of right- and left-moving electrons.\nThe latter requires transition at the bottom of the band which is exponentially\nsuppressed at low temperatures. Our theory is based on the scattering approach\nthat is beyond the Luttinger-liquid limit. We emphasize the crucial role of the\nexchange terms in the three-particle scattering amplitude that was not\ndiscussed in the previous studies.",
        "positive": "Skyrmionic division: Magnetic skyrmions and skyrmion bags are nano-scale spin textures whose\nstability, size and ease of manipulation make them strong contenders for next\ngeneration data and logic applications. Skyrmion bags are composite skyrmions\nof any integer topological degree and this means they have emergent properties\nnot present in unitary degree skyrmions. Here we present models and theoretical\ndescriptions demonstrating the process of skyrmionic division where a skyrmion\nor skyrmion bag can be divided into two or more skyrmionic structures. This\nexciting result could pave the way to entirely new types of skyrmion device in\nthe emerging fields of spintronics and neuromorphic computing."
    },
    {
        "anchor": "A comprehensive first-principle study of borophene-based nano gas sensor\n  with gold electrodes: Using density functional theory combined with nonequilibrium Green's function\nmethod, the transport properties of borophene-based nano gas sensors with gold\nelectrodes are calculated, and comprehensive understandings regarding the\neffects of gas molecules, MoS$_2$ substrate and gold electrodes to the\ntransport properties of borophene are made. Results show that borophene-based\nsensors can be used to detect and distinguish CO, NO, NO$_2$ and NH$_3$ gas\nmolecules, MoS$_2$ substrate leads to a non-linear behavior on the\ncurrent-voltage characteristic, and gold electrodes provide charges to\nborophene and form a potential barrier, which reduced the current values\ncompared to the current of the systems without gold electrodes. Our studies not\nonly provide useful information on the computationally design of\nborophene-based gas sensors, but also help understand the transport behaviors\nand underlying physics of 2D metallic materials with metal electrodes.",
        "positive": "Localization Effect in a 2D Superconducting Network without Disorder: The superconducting properties of a two-dimensional superconducting wire\nnetwork with a new geometry have been measured as a function of the external\nmagnetic field. The extreme localization effect recently predicted for this\nperiodic lattice is revealed as a suppression of the critical current when the\napplied magnetic field corresponds to half a flux quantum per unit cell. For\nthis particular magnetic field, the observed vortex state configuration is\nhighly disordered."
    },
    {
        "anchor": "Evidence for zero-differential resistance states in electronic bilayers: We observe zero-differential resistance states at low temperatures and\nmoderate direct currents in a bilayer electron system formed by a wide quantum\nwell. Several regions of vanishing resistance evolve from the inverted peaks of\nmagneto-intersubband oscillations as the current increases. The experiment,\nsupported by a theoretical analysis, suggests that the origin of this\nphenomenon is based on instability of homogeneous current flow under conditions\nof negative differential resistivity which leads to formation of current\ndomains in our sample, similar to the case of single-layer systems.",
        "positive": "Carbon Nanotubes Band Assignation, Topology, Bloch States and Selection\n  Rules: Various properties of the energy band structures (electronic, phonon, etc.),\nincluding systematic band degeneracy, sticking and extremes, following from the\nfull line group symmetry of the single-wall carbon nanotubes are established.\nThe complete set of quantum numbers consists of quasi momenta (angular and\nlinear or helical) and parities with respect to the z-reversal symmetries and,\nfor achiral tubes, the vertical plane. The assignation of the electronic bands\nis performed, and the generalized Bloch symmetry adapted eigen functions are\nderived. The most important physical tensors are characterized by the same set\nof quantum numbers. All this enables application of the presented exhaustive\nselection rules. The results are discussed by some examples, e.g. allowed\ninterband transitions, conductivity, Raman tensor, etc."
    },
    {
        "anchor": "Steady-State Coherent Transfer by Adiabatic Passage: We propose steady-state electron transport based on coherent transfer by\nadiabatic passage (CTAP) in a linearly arranged triple quantum dot with leads\nattached to the outer dots. Its main feature is repeated steering of single\nelectrons from the first dot to the last dot without relevant occupation of the\nmiddle dot. The coupling to leads enables a steady-state current, whose shot\nnoise is significantly suppressed provided that the CTAP protocol performs\nproperly. This represents an indication for the direct transfer between\nspatially separated dots and, thus, may resolve the problem of finding\nexperimental evidence for the non-occupation of the middle dot.",
        "positive": "Orbital magnetic moments in insulating Dirac systems: Impact on\n  magnetotransport in graphene van der Waals heterostructures: In honeycomb Dirac systems with broken inversion symmetry, orbital magnetic\nmoments coupled to the valley degree of freedom arise due to the topology of\nthe band structure, leading to valley-selective optical dichroism. On the other\nhand, in Dirac systems with prominent spin-orbit coupling, similar orbital\nmagnetic moments emerge as well. These moments are coupled to spin, but\notherwise have the same functional form as the moments stemming from spatial\ninversion breaking. After reviewing the basic properties of these moments,\nwhich are relevant for a whole set of newly discovered materials, such as\nsilicene and germanene, we study the particular impact that these moments have\non graphene nanoengineered barriers with artificially enhanced spin-orbit\ncoupling. We examine transmission properties of such barriers in the presence\nof a magnetic field. The orbital moments are found to manifest in transport\ncharacteristics through spin-dependent transmission and conductance, making\nthem directly accessible in experiments. Moreover, the Zeeman-type effects\nappear without explicitly incorporating the Zeeman term in the models, i.e., by\nusing minimal coupling and Peierls substitution in continuum and the\ntight-binding methods, respectively. We find that a quasiclassical view is able\nto explain all the observed phenomena."
    },
    {
        "anchor": "Interacting electrons in a magnetic field in a center-of-mass free basis: We present an extension of the spin-adapted configuration-interaction method\nfor the computation of four electrons in a quasi two-dimensional quantum dot.\nBy a group-theoretical decomposition of the basis set and working with relative\nand center-of-mass coordinates we obtain an analytical identification of all\nspurious center-of-mass states of the Coulomb-interacting electrons. We find a\nsubstantial reduction in the basis set used for numerical computations. At the\nsame time we increase the accuracy compared to the standard spin-adapted\nconfiguration-interaction method (SACI) due to the absence of distortions\ncaused by an unbalanced cut-off of center-of-mass excitations.",
        "positive": "PH Pfaffian intra and inter correlations in the quantum Hall bilayer: PH Pfaffian topological phase may exist in a uniform system due to strong\nLandau level (LL) mixing according to theoretical predictions based on the Son\n- Dirac composite fermion theory. Numerical investigations in the presence of\nlarge LL mixing are limited due to numerical complexities, when taking into\naccount at least one more LL. Because of this, we apply the same field\ntheoretical approach to the quantum Hall bilayer at total filling factor equal\nto one, for which many numerical studies exist. The most recent work in the\ntorus geometry predicts an intermediate phase (for intermediate distances\nbetween layers) with an even-odd effect. According to our approach, the\nintermediate phase represents a mixed negative-flux $p$-wave pairing i.e.\ncoexisting intra (PH Pfaffian in each layer) and inter (a la PH Pfaffian)\npairing correlations. This again underlines a necessity for strong entanglement\nwith additional degrees of freedom, i.e. at least one more (additional) LL in\nthe search for a stable PH Pfaffian phase in a single layer. Based on the\nanalogy with the bilayer physics we propose a PH Pfaffian wave function that\nresides in two LLs."
    },
    {
        "anchor": "Oscillations of van Hove singularities spacing induced by sub-Angstrom\n  fluctuations of interlayer spacing in graphene superlattices: Physical properties of two-dimensional van der Waals (vdWs) structures depend\nsensitively on both stacking orders and interlayer interactions. Yet, in most\ncases studied to date, the interlayer interaction is considered to be a static\nproperty of the vdWs structures. Here we demonstrate that applying a scanning\ntunneling microscopy (STM) tip pulse on twisted bilayer graphene (TBG) can\ninduce sub-Angstrom fluctuations of the interlayer separation in the TBG, which\nare equivalent to dynamic vertical external pressure of about 10 GPa on the\nTBG. The sub-Angstrom fluctuations of the interlayer separation result in large\noscillations of the energy separations between two van Hove singularities\n(VHSs) in the TBG. The period of the oscillations of the VHSs spacing is\nextremely long, about 500-1000 seconds, attributing to tip-induced local stress\nin the atomic-thick TBG. Our result provides an efficient method to tune and\nmeasure the physical properties of the vdWs structures dynamically.",
        "positive": "Probing the electron-phonon coupling in ozone-doped graphene by Raman\n  spectroscopy: We have investigated the effects of ozone treatment on graphene by Raman\nscattering. Sequential ozone short-exposure cycles resulted in increasing the\n$p$ doping levels as inferred from the blue shift of the 2$D$ and $G$ peak\nfrequencies, without introducing significant disorder. The two-phonon 2$D$ and\n2$D'$ Raman peak intensities show a significant decrease, while, on the\ncontrary, the one-phonon G Raman peak intensity remains constant for the whole\nexposure process. The former reflects the dynamics of the photoexcited\nelectrons (holes) and, specifically, the increase of the electron-electron\nscattering rate with doping. From the ratio of 2$D$ to 2$D$ intensities, which\nremains constant with doping, we could extract the ratio of electron-phonon\ncoupling parameters. This ratio is found independent on the number of layers up\nto ten layers. Moreover, the rate of decrease of 2$D$ and 2$D'$ intensities\nwith doping was found to slowdown inversely proportional to the number of\ngraphene layers, revealing the increase of the electron-electron collision\nprobability."
    },
    {
        "anchor": "Many-Body Effects on Tunneling of Electrons in Magnetic-Field-Induced\n  Quasi One-Dimensional Electron Systems in Semiconductor Nanowhiskers: Effects of the electron-electron interaction on tunneling in a semiconductor\nnanowhisker are studied in a magnetic quantum limit. We consider the system\nwith which bulk and edge states coexist. In bulk states, the temperature\ndependence of the transmission probability is qualitatively similar to that of\na one-dimensional electron system. We investigate contributions of edge states\non transmission probability in bulk states. Those contributions can be\nneglected within our approximation which takes into account only most divergent\nterms at low temperatures.",
        "positive": "Appearance of Topological Phases in Superconducting Nanocircuits: We construct non-Abelian geometric transformations in superconducting\nnanocircuits, which resemble in properties the Aharonov-Bohm phase for an\nelectron transported around a magnetic flux line. The effective magnetic fields\ncan be strongly localized, and the path is traversed in the region where the\nenergy separation between the states involved is at maximum, so that the\nadiabaticity condition is weakened. In particular, we present a scheme of\ntopological charge pumping."
    },
    {
        "anchor": "Lateral tunneling through the controlled barrier between edge channels\n  in a two-dimentional electron system: We study the lateral tunneling through the gate-voltage-controlled barrier,\nwhich arises as a result of partial elimination of the donor layer of a\nheterostructure along a fine strip using an atomic force microscope, between\nedge channels at the depletion-induced edges of a gated two-dimensional\nelectron system. For a sufficiently high barrier a typical current-voltage\ncharacteristic is found to be strongly asymmetric and include, apart from a\npositive tunneling branch, the negative branch that corresponds to the current\noverflowing the barrier. We establish the barrier height depends linearly on\nboth gate voltage and magnetic field and we describe the data in terms of\nelectron tunneling between the outermost edge channels.",
        "positive": "Bosonization of one dimensional fermions out of equilibrium: Bosonization technique for one-dimensional fermions out of equilibrium is\ndeveloped in the framework of the Keldysh action formalism. We first\ndemonstrate how this approach is implemented for free fermions and for the\nproblem of non-equilibrium Fermi edge singularity. We then employ the technique\nto study an interacting quantum wire attached to two electrodes with arbitrary\nenergy distributions. The non-equilibrium electron Green functions, which can\nbe measured via tunneling spectroscopy technique and carry the information\nabout energy distribution, zero-bias anomaly, and dephasing, are expressed in\nterms of functional determinants of single-particle \"counting\" operators. The\ncorresponding time-dependent scattering phase is found to be intrinsically\nrelated to \"fractionalization\" of electron-hole excitations in the tunneling\nprocess and at boundaries with leads. Results are generalized to the case of\nspinful particles as well to Green functions at different spatial points\n(relevant to the problem of dephasing in Luttinger liquid interferometers). For\ndouble-step distributions, the dephasing rates are oscillatory functions of the\ninteraction strength."
    },
    {
        "anchor": "Longitudinal and spin/valley Hall optical conductivity in single layer\n  $MoS_{2}$: A monolayer of $MoS_{2}$ has a non-centrosymmetric crystal structure, with\nspin polarized bands. It is a two valley semiconductor with direct gap falling\nin the visible range of the electromagnetic spectrum. Its optical properties\nare of particular interest in relation to valleytronics and possible device\napplications. We study the longitudinal and the transverse Hall dynamical\nconductivity which is decomposed into charge, spin and valley contributions.\nCircular polarized light associated with each of the two valleys separately is\nconsidered and results are filtered according to spin polarization. Temperature\ncan greatly change the spin admixture seen in the frequency window where they\nare not closely in balance.",
        "positive": "Spectral signatures of non-trivial topology in a superconducting circuit: Topology, like symmetry, is a fundamental concept in understanding general\nproperties of physical systems. In condensed matter systems, non-trivial\ntopology may manifest itself as singular features in the energy spectrum or the\nquantization of observable quantities such as electrical conductance and\nmagnetic flux. Using microwave spectroscopy, we show that a superconducting\ncircuit with three Josephson tunnel junctions in parallel can possess energy\ndegeneracies indicative of $\\textrm{\\emph{intrinsic}}$ non-trivial topology. We\nidentify three topological invariants, one of which is related to a hidden\nquantum mechanical supersymmetry. Depending on fabrication parameters, devices\nare gapless or not, and fall on a simple phase diagram which is shown to be\nrobust to perturbations including junction imperfections, asymmetry, and\ninductance. Josephson tunnel junction circuits, which are readily fabricated\nwith conventional microlithography techniques, allow access to a wide range of\ntopological systems which have no condensed matter analog. Notable spectral\nfeatures of these circuits, such as degeneracies and flat bands, may be\nleveraged for quantum information applications, whereas quantized transport\nproperties could be useful for metrology applications."
    },
    {
        "anchor": "Hall Viscosity of the Composite-Fermion Fermi Seas for Fermions and\n  Bosons: The Hall viscosity has been proposed as a topological property of\nincompressible fractional quantum Hall states and can be evaluated as Berry\ncurvature. This paper reports on the Hall viscosities of composite-fermion\nFermi seas at $\\nu=1/m$, where $m$ is even for fermions and odd for bosons. A\nwell-defined value for the Hall viscosity is not obtained by viewing the $1/m$\ncomposite-fermion Fermi seas as the $n\\rightarrow \\infty$ limit of the Jain\n$\\nu=n/(nm\\pm 1)$ states, whose Hall viscosities $(\\pm n+m)\\hbar \\rho/4$\n($\\rho$ is the two-dimensional density) approach $\\pm \\infty$ in the limit\n$n\\rightarrow \\infty$. A direct calculation shows that the Hall viscosities of\nthe composite-fermion Fermi sea states are finite, and also relatively stable\nwith system size variation, although they are not topologically quantized in\nthe entire $\\tau$ space. I find that the $\\nu=1/2$ composite-fermion Fermi sea\nwave function for a square torus yields a Hall viscosity that is expected from\nparticle-hole symmetry and is also consistent with the orbital spin of $1/2$\nfor Dirac composite fermions. I compare my numerical results with some\ntheoretical conjectures.",
        "positive": "Spin transfer torque and exchange coupling in Josephson junctions with\n  ferromagnetic superconductor reservoirs: In this paper, the spin transfer torque (STT) and the exchange coupling of\nthe Josephson junctions containing interesting cases of\ndiffusive/ballistic-triplet/singlet ferromagnetic superconductor materials\ntogether with diffusive Josephson junction of the form\nS$_{1}$/F$_{1}$/I$_1$/N/I$_2$/F$_2$ with I being insulating barrier are\ninvestigated. Using the Nazarov quantum circuit theory, it is found that for\nthe diffusive FS$_1$/N/FS$_2$ structure the only emerged torque in normal\ndirection to the plane of the exchange fields of F$_1$ and F$_2$ results in\nantiparallel/parallel or vice versa parallel/antiparallel transition of\nfavorable exchange coupling depending on the considered parameters of the\nsystem, including the nonmagnetic spacer thickness, the superconducting phase\ndifference, the length and the exchange field of the ferromagnets. Furthermore,\nthe analyze of the width of the transitions, the phase difference interval in\nwhich an interlayer length-induced antiparallel/parallel transition can be\noccurred, is performed. For instance, as the exchange field or the temperature\nincreases, the interval of phase difference gets larger. On the other hand,\nballistic Josephson junction containing the triplet ferromagnetic\nsuperconductor reservoirs solving the 16$\\times$16 Bogoliubov-de-Gennes\nequation is studied. It is found that although the exchange fields of the FS\nare laid in the z and y direction, the STT interestingly exists in all three\ndirections of x, y and z. This exciting finding suggests that the favorable\nequilibrium configuration concerning the least exchange coupling occurs in the\nrelative exchange field direction different from 0 or $\\pi$. To the best of our\nknowledge it is for the first time that the occurrence of the in-plane STT is\nreported. Moreover, the occurrence of the beat like behavior with two\noscillation period for the out-of-plane STT is interestingly acquired."
    },
    {
        "anchor": "Electric field manipulation of surface states in topological semimetals: We investigate the consequences of applying electric fields perpendicularly\nto thin films of topological semimetals. In particular, we consider Weyl and\nDirac semimetals in a configuration such that their surface Fermi arcs lie on\nopposite edges of the films. We develop an analytical approach based on\nperturbation theory and a single-surface approximation and we compare our\nanalytical results with numerical calculations. The effect of the electric\nfield on the dispersion is twofold: it shifts the dispersion relation and\nrenormalizes the Fermi velocity, which would, in turn, have direct effects on\nquantum transport measurements. Additionally, it modifies the spatial decay\nproperties of surface states which will impact the connection of the Fermi arcs\nin opposite sides of a narrow thin film.",
        "positive": "Inverse Edelstein Effect: We provide a precise microscopic definition of the recently observed \"Inverse\nEdelstein Effect\" (IEE), in which a non-equilibrium spin accumulation in the\nplane of a two-dimensional (interfacial) electron gas drives an electric\ncurrent perpendicular to its own direction. The drift-diffusion equations that\ngovern the effect are presented and applied to the interpretation of the\nexperiments."
    },
    {
        "anchor": "Effects of external driving on the coherence time of a Josephson\n  junction qubit in a bath of two level fluctuators: We study the effect of external driving on the two level systems (TLSs)\nassumed to be a major obstacle in increasing the coherence time of solid state\nJosephson-junction qubits. We find, by use of a Bloch-Redfield approach, that\nexternal driving has two major effects on the TLS. The first is increased\nfluctuations between the two states of the TLS, the significance of this effect\ncompared to thermal fluctuations depend on the energy splitting of the TLS\ncompared to temperature. The second effect is a reduction in the intensity of\nthe noise spectrum at low frequencies, and at the same time an increase in\nintensity around the renormalized Rabi frequency of the TLS, the driving\nfrequency and at beatings between these two frequencies. Finally we study the\nensemble averaged noise spectrum for a typical distribution of TLSs known to\ngive origin to $\\propto 1/f$ noise. We find that strong driving leads to\nreduced noise at low frequencies, and therefore to an increased dephasing time\n$T_2^Q$ of the qubit. However this effect is exponentially suppressed when the\ndriving frequency is large compared to temperature, as we typically find for\nJosephson qubits. We suggest that external driving at frequencies much lower\nthan the qubit frequency might be used in order to enhance the the qubit\ncoherence time.",
        "positive": "Assessment of Dressed Time-Dependent Density-Functional Theory for the\n  Low-Lying Valence States of 28 Organic Chromophores: Almost all time-dependent density-functional theory (TDDFT) calculations of\nexcited states make use of the adiabatic approximation, which implies a\nfrequency-independent exchange-correlation kernel that limits applications to\none-hole/one-particle states. To remedy this problem, Maitra et\nal.[J.Chem.Phys. 120, 5932 (2004)] proposed dressed TDDFT (D-TDDFT), which\nincludes explicit two-hole/two-particle states by adding a frequency-dependent\nterm to adiabatic TDDFT. This paper offers the first extensive test of D-TDDFT,\nand its ability to represent excitation energies in a general fashion. We\npresent D-TDDFT excited states for 28 chromophores and compare them with the\nbenchmark results of Schreiber et al.[J.Chem.Phys. 128, 134110 (2008).] We find\nthe choice of functional used for the A-TDDFT step to be critical for\npositioning the 1h1p states with respect to the 2h2p states. We observe that\nD-TDDFT without HF exchange increases the error in excitations already\nunderestimated by A-TDDFT. This problem is largely remedied by implementation\nof D- TDDFT including Hartree-Fock exchange."
    },
    {
        "anchor": "Strong Coupling between Microwave Photons and Nanomagnet Magnons: Coupled microwave photon-magnon hybrid systems offer promising applications\nby harnessing various magnon physics. At present, in order to realize high\ncoupling strength between the two subsystems, bulky ferromagnets with large\nspin numbers are utilized, which limits their potential applications for\nscalable quantum information processing. In this paper, by enhancing single\nspin coupling strength using lithographically defined superconducting\nresonators, we report high cooperativities between a resonator mode and a\nKittel mode in nanometer thick Permalloy wires. The on-chip, lithographically\nscalable, and superconducting quantum circuit compatible design provides a\ndirect route towards realizing hybrid quantum systems with nanomagnets, whose\ncoupling strength can be precisely engineered and dynamic properties can be\ncontrolled by various mechanisms derived from spintronic studies.",
        "positive": "Chiral anomaly from strain-induced gauge fields in Dirac and Weyl\n  semimetals: Dirac and Weyl semimetals form an ideal platform for testing ideas developed\nin high energy physics to describe massless relativistic particles. One such\nquintessentially field-theoretic idea of chiral anomaly already resulted in the\nprediction and subsequent observation of the pronounced negative\nmagnetoresistance in these novel materials for parallel electric and magnetic\nfields. Here we predict that the chiral anomaly occurs - and has experimentally\nobservable consequences - when real electromagnetic fields E and B are replaced\nby strain-induced pseudo-electromagnetic fields e and b. For example, a uniform\npseudomagnetic field b is generated when a Weyl semimetal nanowire is put under\ntorsion. In accord with the chiral anomaly equation we predict a negative\ncontribution to the wire resistance proportional to the square of the torsion\nstrength. Remarkably, left and right moving chiral modes are then spatially\nsegregated to the bulk and surface of the wire forming a \"topological coaxial\ncable\". This produces hydrodynamic flow with potentially very long relaxation\ntime. Another effect we predict is the ultrasonic attenuation and\nelectromagnetic emission due to a time periodic mechanical deformation causing\npseudoelectric field e. These novel manifestations of the chiral anomaly are\nmost striking in the semimetals with a single pair of Weyl nodes but also occur\nin Dirac semimetals such as Cd3As2 and Na3Bi and Weyl semimetals with unbroken\ntime reversal symmetry."
    },
    {
        "anchor": "Tailoring the electron and hole Land\u00e9 factors in lead halide\n  perovskite nanocrystals by quantum confinement and halide exchange: The tunability of the optical properties of lead halide perovskite\nnanocrystals makes them highly appealing for applications. Both, halide anion\nexchange and quantum confinement pave the way for tailoring their band gap\nenergy. For spintronics applications, the Land\\'e g-factors of electrons and\nhole are of great importance. By means of the empirical tight-binding and\n$\\textbf{k}\\cdot\\textbf{p}$ methods, we calculate them for nanocrystals of the\nclass of all-inorganic lead halide perovskites CsPb$X_3$ ($X =\n\\text{I},\\,\\text{Br},\\,\\text{Cl}$). The hole g-factor as function of the band\ngap follows the universal dependence found for bulk perovskites, while for the\nelectrons a considerable modification is predicted. Based on the\n$\\textbf{k}\\cdot\\textbf{p}$ analysis we conclude that this difference arises\nfrom the interaction of the bottom conduction band with the spin-orbit split\nelectron states. The model predictions are confirmed by experimental data for\nthe electron and hole g-factors in CsPbI3 nanocrystals placed in a glass\nmatrix, measured by time-resolved Faraday ellipticity in a magnetic field at\ncryogenic temperatures.",
        "positive": "Influence of sample geometry on inductive damping measurement methods: We study the precession frequency and effective damping of patterned\npermalloy thin films of different geometry using integrated inductive test\nstructures. The test structures consist of coplanar wave guides fabricated onto\npatterned permalloy stripes of different geometry. The width, length and\nposition of the permalloy stripe with respect to the center conductor of the\nwave guide are varied. The precession frequency and effective damping of the\ndifferent devices is derived by inductive measurements in time and frequency\ndomain in in-plane magnetic fields. While the precession frequencies do not\nreveal a significant dependence on the sample geometry we find a decrease of\nthe measured damping with increasing width of the permalloy centered underneath\nthe center conductor of the coplanar wave guide. We attribute this effect to an\nadditional damping contribution due to inhomogeneous line broadening at the\nedges of the permalloy stripes which does not contribute to the inductive\nsignal provided the permalloy stripe is wider than the center conductor.\nConsequences for inductive determination of the effective damping using such\nintegrated reference samples are discussed."
    },
    {
        "anchor": "Quantum dots with Rashba spin-orbit coupling: We present results on the effects of spin-orbit coupling on the electronic\nstructure of few-electron interacting quantum dots. The ground-state properties\nas a function of the number of electrons in the dot $N$ are calculated by means\nof spin density functional theory. We find a suppression of Hund's rule due to\nthe competition of the Rashba effect and exchange interaction. Introducing an\nin-plane Zeeman field leads to a paramagnetic behavior of the dot in a closed\nshell configuration, and to spin texture in space.",
        "positive": "Nanoscale vector electric field imaging using a single electron spin: The ability to perform nanoscale electric field imaging of elementary charges\nat ambient temperatures will have diverse interdisciplinary applications. While\nthe nitrogen-vacancy (NV) center in diamond is capable of high-sensitivity\nelectrometry, demonstrations have so far been limited to macroscopic field\nfeatures or detection of single charges internal to diamond itself. In this\nwork we greatly extend these capabilities by using a shallow NV center to image\nthe electric field of a charged atomic force microscope tip with nanoscale\nresolution. This is achieved by measuring Stark shifts in the NV spin-resonance\ndue to AC electric fields. To achieve this feat we employ for the first time,\nthe integration of Qdyne with scanning quantum microscopy. We demonstrate near\nsingle charge sensitivity of $\\eta_e = 5.3$ charges/$\\sqrt{\\text{Hz}}$, and\nsub-charge detection ($0.68e$). This proof-of-concept experiment provides the\nmotivation for further sensing and imaging of electric fields using NV centers\nin diamond."
    },
    {
        "anchor": "Spin-splitting in GaAs 2D holes: We present quantitative measurements and calculations of the spin-orbit\ninduced zero-magnetic-field spin-splitting in two-dimensional (2D) hole systems\nin modulation-doped GaAs (311)A quantum wells. The results show that the\nsplitting is large and tunable. In particular, via a combination of back- and\nfront-gate biases, we can tune the splitting while keeping the 2D hole density\nconstant. The data also reveal a surprising result regarding the\nmagnetoresistance (Shubnikov-de Haas) oscillations in a 2D system with\nspin-split energy bands: the frequencies of the oscillations are {\\it not}\nsimply related to the population of the spin-subbands. Next we concentrate on\nthe metallic-like behavior observed in these 2D holes and its relation to\nspin-splitting. The data indicate that the metallic behavior is more pronounced\nwhen two spin-subbands with unequal populations are occupied. Our measurements\nof the magnetoresistance of these 2D hole systems with an in-plane magnetic\nfield corroborate this conclusion: while the system is metallic at zero\nmagnetic field, it turns insulating when one of the spin-subbands is\ndepopulated at high magnetic field.",
        "positive": "Two-dimensional quantum transport of multivalley (111) surface state in\n  topological crystalline insulator SnTe thin films: Magneto-transport properties of (111)-oriented single-crystal thin films of\nSnTe were investigated. SnTe (111) thin films were epitaxially grown on a BaF2\nsubstrate by molecular beam epitaxy. By optimizing the growth conditions and\nthe thickness of the films, the bulk carrier density could be reduced, making\nit possible to detect the surface transport. In the magneto-conductance (MC)\nmeasurement, a cusp-like feature around zero magnetic field was observed, which\nis attributed to the weak-antilocalization effect of the transport in the\ntopological surface state. Detailed analysis of this negative MC reveals a\nreduced number of transport channels contributing to the surface transport,\nsuggesting a strong coupling between Dirac valleys on the SnTe (111) surface,\nas a characteristic feature of the transport in the multivalley structure of\nTCI."
    },
    {
        "anchor": "Theory of the dc Magnetotransport in Laterally Modulated Quantum Hall\n  Systems Near Filling $\u03bd={1/2}$: A quasiclassical theory for dc magnetotransport in a modulated quantum Hall\nsystem near filling factor $\\nu={1/2}$ is presented. A weak one-dimensional\nelectrostatic potential acts on the two-dimensional electron gas. Closed form\nanalytic expressions are obtained for the resistivity $\\rho_\\perp$\ncorresponding to a current at right angles to the direction of the modulation\nlines as well as a smaller component $\\rho_{||}$ for a current along the\ndirection of the modulation lines. It is shown that both resistivity components\nare affected by the presence of the modulation. Numerical results are presented\nfor $\\rho_\\perp$ and $\\rho_{||}$ and show reasonable agreement with the results\nof recent experiments.",
        "positive": "Electrostatic Imaging of Encapsulated Graphene: Devices made from two dimensional materials such as graphene and transition\nmetal dichalcogenides exhibit remarkable electronic properties of interest to\nmany subdisciplines of nanoscience. Owing to their 2D nature, their quality is\nhighly susceptible to contamination and degradation when exposed to the ambient\nenvironment. Protecting the 2D layers by encapsulation between hexagonal boron\nnitride layers significantly improves their quality. Locating these samples\nwithin the encapsulant and assessing their integrity prior to further\nprocessing then becomes challenging. Here we show that conductive scanning\nprobe techniques such as electrostatic force and Kelvin force microscopy makes\nit possible to visualize the encapsulated layers, their charge environment and\nlocal defects including cracks and bubbles on the sub-micrometer scale. Our\ntechniques are employed without requiring electrical contact to the embedded\nlayer, providing valuable feedback on the local electronic quality prior to any\ndevice etching or electrode deposition. We show that these measurement modes,\nwhich are simple extensions of atomic force microscopy, are perfectly suited\nfor imaging encapsulated conductors and their local charge environments."
    },
    {
        "anchor": "Hybrid magnonics: physics, circuits and applications for coherent\n  information processing: Hybrid dynamic systems have recently gained interests with respect to both\nfundamental physics and device applications, particularly with their potential\nfor coherent information processing. In this perspective, we will focus on the\nrecent rapid developments of magnon-based hybrid systems, which seek to combine\nmagnonic excitations with diverse excitations for transformative applications\nin devices, circuits and information processing. Key to their promising\npotentials is that magnons are highly tunable excitations and can be easily\nengineered to couple with various dynamic media and platforms. The capability\nof reaching strong coupling with many different excitations has positioned\nmagnons well for studying solid-state coherent dynamics and exploiting unique\nfunctionality. In addition, with their gigahertz frequency bandwidth and the\nease of fabrication and miniaturization, magnonic devices and systems can be\nconveniently integrated into microwave circuits for mimicking a broad range of\ndevice concepts that have been applied in microwave electronics, photonics and\nquantum information. We will discuss a few potential directions for advancing\nmagnon hybrid systems, including on-chip geometry, novel coherent magnonic\nfunctionality, and coherent transduction between different platforms. As future\noutlook, we will discuss the opportunities and challenges of magnonic hybrid\nsystems for their applications in quantum information and magnonic logic.",
        "positive": "Acoustically Induced Giant Synthetic Hall Voltages in Graphene: Any departure from graphene's flatness leads to the emergence of artificial\ngauge fields that act on the motion of the Dirac fermions through an associated\npseudomagnetic field. Here, we demonstrate the tunability of strong gauge\nfields in non-local experiments using a large planar graphene sheet that\nconforms to the deformation of a piezoelectric layer by a surface acoustic\nwave. The acoustic wave induces a longitudinal and a giant synthetic Hall\nvoltage in the absence of external magnetic fields. The superposition of a\nsynthetic Hall potential and a conventional Hall voltage can annihilate the\nsample's transversal potential at large external magnetic fields. Surface\nacoustic waves thus provide a promising and facile avenue for the exploit of\ngauge fields in large planar graphene systems."
    },
    {
        "anchor": "Localization of Two Interacting Particles in One-Dimensional Random\n  Potential: We investigate the localization of two interacting particles in\none-dimensional random potential. Our definition of the two-particle\nlocalization length, $\\xi$, is the same as that of v. Oppen et al. [Phys. Rev.\nLett. 76, 491 (1996)] and $\\xi$'s for chains of finite lengths are calculated\nnumerically using the recursive Green's function method for several values of\nthe strength of the disorder, $W$, and the strength of interaction, $U$. When\nU=0, $\\xi$ approaches a value larger than half the single-particle localization\nlength as the system size tends to infinity and behaves as $\\xi \\sim\nW^{-\\nu_0}$ for small $W$ with $\\nu_0 = 2.1 \\pm 0.1$. When $U\\neq 0$, we use\nthe finite size scaling ansatz and find the relation $\\xi \\sim W^{-\\nu}$ with\n$\\nu = 2.9 \\pm 0.2$. Moreover, data show the scaling behavior $\\xi \\sim\nW^{-\\nu_0} g(|U|/W^\\Delta)$ with $\\Delta = 4.0 \\pm 0.5$.",
        "positive": "Role of Magnetic Field in Self-Oscillation of Nanomagnet Excited by Spin\n  Torque: The critical current of the self-oscillation of spin torque oscillator (STO)\nconsisting of a perpendicularly magnetized free layer and an in-plane\nmagnetized pinned layer was studied by solving the Landau-Lifshitz-Gilbert\n(LLG) equation. We found that the critical current diverged at certain field\ndirections, indicating that the self-oscillation does not occur at these\ndirections. It was also found that the sign of the critical current changed\ndepending on the applied field direction."
    },
    {
        "anchor": "Non-linear exciton spin-splitting in single InAs/GaAs self-assembled\n  quantum structures in ultrahigh magnetic fields: We report on the magnetic field dispersion of the exciton spin-splitting and\ndiamagnetic shift in single InAs/GaAs quantum dots (QDs) and dot molecules\n(QDMs) up to $B$ = 28 T. Only for systems with strong geometric confinement,\nthe dispersions can be well described by simple field dependencies, while for\ndots with weaker confinement considerable deviations are observed: most\nimportantly, in the high field limit the spin-splitting shows a non-linear\ndependence on $B$, clearly indicating light hole admixtures to the valence band\nground state.",
        "positive": "Influences of spin accumulation on the intrinsic spin Hall effect in two\n  dimensional electron gases with Rashba spin-orbit coupling: In a two dimensional electron gas with Rashba spin-orbit coupling, the\nexternal electric field may cause a spin Hall current in the direction\nperpendicular to the electric field. This effect was called the intrinsic spin\nHall effect. In this paper, we investigate the influences of spin accumulation\non this intrinsic spin Hall effect. We show that due to the existence of\nboundaries in a real sample, the spin Hall current generated by the intrinsic\nspin Hall effect will cause spin accumulation near the edges of the sample, and\nin the presence of spin accumulation, the spin Hall conductivity will not have\na universal value. The influences of spin accumulation on the intrinsic spin\nHall effect in narrow strips of two dimensional electron gases with Rashba\nspin-orbit coupling are investigated in detail."
    },
    {
        "anchor": "Generic ordering of structural transitions in quasi-one-dimensional\n  Wigner crystals: We investigate the dependence of the structural phase transitions in an\ninfinite quasi-one-dimensional system of repulsively interacting particles on\nthe profile of the confining channel. Three different functional expressions\nfor the confinement potential related to real experimental systems are used\nthat can be tuned continuously from a parabolic to a hard-wall potential in\norder to find a thorough understanding of the ordering of the chain-like\nstructure transitions. We resolve the longstanding issue why the most theories\npredicted a 1-2-4-3-4 sequence of chain configurations with increasing density,\nwhile some experiments found the 1-2-3-4 sequence.",
        "positive": "Transport through a finite Hubbard chain connected to reservoirs: The dc conductance through a finite Hubbard chain of size N coupled to two\nnoninteracting leads is studied at T = 0 in an electron-hole symmetric case.\nAssuming that the perturbation expansion in U is valid for small N (=1,2,3,...)\nowing to the presence of the noninteracting leads, we obtain the self-energy at\n\\omega = 0 analytically in the real space within the second order in U. Then,\nwe calculate the inter-site Green's function which connects the two boundaries\nof the chain, G_{N1}, solving the Dyson equation. The conductance can be\nobtained through G_{N1}, and the result shows an oscillatory behavior as a\nfunction of N. For odd N, a perfect transmission occurs independent of U. This\nis due to the inversion and electron-hole symmetries, and is attributed to a\nKondo resonance appearing at the Fermi level. On the other hand, for even N,\nthe conductance is a decreasing function of N and U."
    },
    {
        "anchor": "Peculiar Band Gap Structure of Graphene Nanoribbons: Graphene nanoribbons are quasi-one-dimensional meterials with finite width.\nCharacterizing a wide class of nanoribbons by edge shape and width, we make a\nsystematic analysis of their electronic properties. The band gap structure of\nnanoribbons is shown to exhibit a valley structure with stream-like sequences\nof metallic or almost metallic nanoribbons. Among them, all zigzag nanoribbons\nare metallic, and armchair nanoribbons are metallic by period of 3. We find\nthat these stream-like sequences correspond to equi-width curves, and that the\nband gap of chiral and armchair nanoribbons oscillate as a function of the\nwidth. Furthermore a possible application of nanoribbons to nanoelectronics is\ndiscussed.",
        "positive": "Massive and massless Dirac fermions in Pb1-xSnxTe topological\n  crystalline insulator probed by magneto-optical absorption: Dirac fermions in condensed matter physics hold great promise for novel\nfundamental physics, quantum devices and data storage applications. IV-VI\nsemiconductors, in the inverted regime, have been recently shown to exhibit\nmassless topological surface Dirac fermions protected by crystalline symmetry,\nas well as massive bulk Dirac fermions. Under a strong magnetic field (B), both\nsurface and bulk states are quantized into Landau levels that disperse as\nB^1/2, and are thus difficult to distinguish. In this work, magneto-optical\nabsorption is used to probe the Landau levels of high mobility Bi-doped\nPb0.54Sn0.46Te topological crystalline insulator (111)-oriented films. The high\nmobility achieved in these thin film structures allows us to probe and\ndistinguish the Landau levels of both surface and bulk Dirac fermions and\nextract valuable quantitative information about their physical properties. This\nwork paves the way for future magnetooptical and electronic transport\nexperiments aimed at manipulating the band topology of such materials."
    },
    {
        "anchor": "Deformation of graphene sheet: Interaction of fermions with phonons: We construct an effective low energy Hamiltonian which describes fermions\ndwelling on a deformed honeycomb lattice with dislocations and disclinations,\nand with an arbitrary hopping parameters of the corresponding tight binding\nmodel. It describes the interaction of fermions with a 2d gravity and has also\na local SU(2) gauge invariance of the group of rotations. We reformulate the\nmodel as interaction of fermions with the deformation of the lattice, which\nforms a phonon field. We calculate the response of fermion currents to the\nexternal deformation or phonon field, which is a result of a Z_2 anomaly. This\ncan be detected experimentally.",
        "positive": "Composite Majorana Fermion Wavefunctions in Nanowires: We consider Majorana fermions (MFs) in quasi-one-dimensional nanowire systems\ncontaining normal and superconducting sections where the topological phase\nbased on Rashba spin orbit interaction can be tuned by magnetic fields. We\nderive explicit analytic solutions of the MF wavefunction in the weak and\nstrong spin orbit interaction regimes. We find that the wavefunction for one\nsingle MF is a composite object formed by superpositions of different MF\nwavefunctions which have nearly disjoint supports in momentum space. These\ncontributions are coming from the extrema of the spectrum, one centered around\nzero momentum and the other around the two Fermi points. As a result, the\nvarious MF wavefunctions have different localization lengths in real space and\ninterference among them leads to pronounced oscillations of the MF probability\ndensity. For a transparent normal-superconducting junction we find that in the\ntopological phase the MF leaks out from the superconducting into the normal\nsection of the wire and is delocalized over the entire normal section, in\nagreement with recent numerical results by Chevallier et al. (arXiv:1203.2643)."
    },
    {
        "anchor": "An observable effect of spin inertia in slow magneto-dynamics: Increase\n  of the switching error rates in nanoscale ferromagnets: The Landau-Lifshitz-Gilbert (LLG) equation, used to model magneto-dynamics in\nferromagnets, tacitly assumes that the angular momentum associated with spin\nprecession can relax instantaneously when the real or effective magnetic field\ncausing the precession is turned off. This neglect of \"spin inertia\" is\nunphysical and would violate energy conservation. Recently, the LLG equation\nwas modified to account for inertia effects. The consensus, however, seems to\nbe that such effects would be unimportant in slow magneto-dynamics that take\nplace over time scales much longer that the relaxation time of the angular\nmomentum, which is typically few fs to perhaps ~100 ps in ferromagnets. Here,\nwe show that there is at least one very serious and observable effect of spin\ninertia even in slow magneto-dynamics. It involves the switching error\nprobability associated with flipping the magnetization of a nanoscale\nferromagnet with an external agent, such as a magnetic field. The switching may\ntake ~ns to complete when the field strength is close to the threshold value\nfor switching, which is much longer than the angular momentum relaxation time,\nand yet the effect of spin inertia is felt in the switching error probability.\nThis is because the ultimate fate of a switching trajectory, i.e. whether it\nresults in success or failure, is influenced by what happens in the first few\nps of the switching action when nutational dynamics due to spin inertia holds\nsway. Spin inertia increases the error probability, which makes the switching\nmore error-prone. This has vital technological significance because it relates\nto the reliability of magnetic logic and memory.",
        "positive": "Imaging the Flow of Holes from a Collimating Contact in Graphene: A beam of holes formed in graphene by a collimating contact is imaged using a\nliquid-He cooled scanning probe microscope (SPM). The mean free path of holes\nis greater than the device dimensions. A zigzag shaped pattern on both sides of\nthe collimating contact absorb holes that enter at large angles. The image\ncharge beneath the SPM tip defects holes, and the pattern of flow is imaged by\ndisplaying the change in conductance between contacts on opposite sides, as the\ntip is raster scanned across the sample. Collimation is confirmed by bending\nhole trajectories away from the receiving contact with an applied magnetic\nfield. The SPM images agree well with ray-tracing simulations."
    },
    {
        "anchor": "Effect of a Coulombic dot-lead coupling on the dynamics of a quantum dot: The effect of a Coulombic coupling on the dynamics of a quantum dot\nhybridized to leads is determined. The calculation treats the interaction\nbetween charge fluctuations on the dot and the dynamically generated image\ncharge in the leads. A formally exact solution is presented for a dot coupled\nto a Luttinger liquid and an approximate solution, equivalent to treating the\nlead dynamics within a random phase approximation, is given for a dot coupled\nto a two- or three-dimensional metallic lead. The leading divergences arising\nfrom the long-ranged Coulomb interaction are found to cancel, so that in the\ntwo- and three-dimensional cases the quantum-dot dynamics is equivalent to that\nobtained by neglecting both the dot-lead Coulomb coupling and the Coulomb\nrenormalization of the lead electrons, while in the one-dimensional case the\ndot-lead mixing is enhanced relative to the non-interacting case. Explicit\nresults are given for the short-time dynamics.",
        "positive": "Electronic properties of curved few-layers graphene: a geometrical\n  approach: We show the presence of non-relativistic L\\'evy-Leblond fermions in flat\nthree- and four-layers graphene with AB stacking, extending the results\nobtained in [Curvatronics2017] for bilayer graphene. When the layer is curved\nwe obtain a set of equations for Galilean fermions that are a variation of\nthose of L\\'evy-Leblond with a well defined combination of pseudospin, and that\nadmit L\\'evy-Leblond spinors as solutions in an approriate limit. The local\nenergy of such Galilean fermions is sensitive to the intrinsic curvature of the\nsurface. We discuss the relationship between two-dimensional pseudospin,\nlabelling layer degrees of freedom, and the different energy bands. For\nL\\'evy-Leblond fermions an interpretation is given in terms of massless\nfermions in an effective 4D spacetime, and in this case the pseudospin is\nrelated to four dimensional chirality. A non-zero energy band gap between\nconduction and valence electronic bands is obtained for surfaces with positive\ncurvature."
    },
    {
        "anchor": "A model of an optical biosensor detecting environment: Heller et. Al. (Science 311, 508 (2006)) demonstrated the first DNA-CN\noptical sensor by wrapping a piece of double-stranded DNA around the surface of\nsingle-walled carbon nanotubes (CN). This new type of optical device can be\nplaced inside living cells and detect trace amounts of harmful contaminants by\nmeans of near infrared light. Using a simple exciton theory in nanostructures\nand the phenomena of B-Z structural phase transition of DNA, we investigate the\nworking principle of this new class of optical biosensor from DNA by using the\nnanostructure surface as a sensor to detect the property change of DNA as it\nresponds to the presence of target ions. We also propose some new design models\nby replacing carbon nanotubes with graphene ribbon semiconductors.",
        "positive": "Fractal Butterflies of Chiral Fermions in Bilayer Graphene: Phase\n  Transitions and Emergent Properties: We report on our studies of fractal butterflies in biased bilayer graphene in\nthe fractional quantum Hall effect (FQHE) regime. We have considered the case\nwhen the external periodic potential is present in one layer and have\nillustrated the effect of varying both the periodic potential strength and the\nbias voltage on the FQHE and the butterfly energy gaps. Interestingly, the\nbutterfly spectra exhibits remarkable phase transitions between the FQHE gap\nand the butterfly gap for chiral electrons in bilayer graphene, by varying\neither the periodic potential strength or the bias voltage. We also find that,\nin addition to those phase transitions, by varying the bias voltage one can\nessentially control the periodic potential strength experienced by the\nelectrons."
    },
    {
        "anchor": "Localized spin waves in isolated $k\u03c0$ skyrmions: The localized magnon modes of isolated $k\\pi$ skyrmions on a field-polarized\nbackground are analyzed based on the Landau-Lifshitz-Gilbert equation within\nthe terms of an atomistic classical spin model, with system parameters based on\nthe Pd/Fe biatomic layer on Ir(111). For increasing skyrmion order $k$ a higher\nnumber of excitation modes are found, including modes with nodes in the radial\neigenfunctions. It is shown that at low fields $2\\pi$ and $3\\pi$ skyrmions are\ndestroyed via a burst instability connected to a breathing mode, while $1\\pi$\nskyrmions undergo an elliptic instability. At high fields all $k\\pi$ skyrmions\ncollapse due to the instability of a breathing mode. The effective damping\nparameters of the spin waves are calculated in the low Gilbert damping limit,\nand they are found to diverge in the case of the lowest-lying modes at the\nburst and collapse instabilities, but not at the elliptic instability. It is\nshown that the breathing modes of $k\\pi$ skyrmions may become overdamped at\nhigher Gilbert damping values.",
        "positive": "Explanation of the tunneling phenomena between the edges of two lateral\n  quantum Hall systems: We identify the physics behind the results of recent measurements [W. Kang et\nal., Nature 403, 59 (2000)] of electron transfer between the edges of two\ntwo-dimensional electron systems (2DES). We find that a consistent explanation\nof all of the observed phenomena is possible if the barrier between the 2DES is\nsurrounded by a strong potential well that supports quantum railroads of edge\nchannels that, in the presence of disorder, exhibit directed localization."
    },
    {
        "anchor": "Scaling of Majorana Zero-Bias Conductance Peaks: We report an experimental study of the scaling of zero-bias conductance peaks\ncompatible with Majorana zero modes as a function of magnetic field, tunnel\ncoupling, and temperature in one-dimensional structures fabricated from an\nepitaxial semiconductor-superconductor heterostructure. Results are consistent\nwith theory, including a peak conductance that is proportional to tunnel\ncoupling, saturates at $2e^2/h$, decreases as expected with field-dependent\ngap, and collapses onto a simple scaling function in the dimensionless ratio of\ntemperature and tunnel coupling.",
        "positive": "Optical orientation of the homogeneous non-equilibrium Bose-Einstein\n  condensate of bright excitons (polaritons): A simple model, describing the dynamics of the non-equilibrium pseudospin of\na homogeneous Bose-Einstein condensate of exciton polaritons, has been\nformulated. It explains the suppression of spin splitting of a non-equilibrium\npolariton condensate in an external magnetic field, the optical alignment, and\nthe conversion of alignment into orientation of polaritons. It has been shown\nthat inverse effects are possible, to wit, the spontaneous circular\npolarization and the enhancement of spin splitting of a non-equilibrium\ncondensate of polaritons in the absence of external field."
    },
    {
        "anchor": "Quantum transport and the Wigner distribution function for Bloch\n  electrons in spatially homogeneous electric and magnetic fields: The theory of Bloch electron dynamics for carriers in homogeneous electric\nand magnetic fields of arbitrary time dependence is developed in the framework\nof the Liouville equation. The Wigner distribution function (WDF) is determined\nfrom the single particle density matrix in the ballistic regime, i.e.,\ncollision effects are excluded. The single particle transport equation is\nestablished with the electric field described in the vector potential gauge,\nand the magnetic field is treated in the symmetric gauge.\n  The general approach is to employ the accelerated Bloch state representation\n(ABR) as a basis so that the dependence upon the electric field, including\nmultiband Zener tunneling, is treated exactly. In the formulation of the WDF,\nwe transform to a new set of variables so that the final WDF is gauge invariant\nand is expressed explicitly in terms of the position, kinetic momentum, and\ntime.\n  The methodology for developing the WDF is illustrated by deriving the exact\nWDF equation for free electrons in homogeneous electric and magnetic fields.\nThe methodology is then extended to the case of electrons described by an\neffective Hamiltonian corresponding to an arbitrary energy band function. In\ntreating the problem of Bloch electrons in a periodic potential, the\nmethodology for deriving the WDF reveals a multiband character due to the\ninherent nature of the Bloch states. In examining the single-band WDF, it is\nfound that the collisionless WDF equation matches the equivalent Boltzmann\ntransport equation to first order in the magnetic field. These results are\nnecessarily extended to second order in the magnetic field by employing a\nunitary transformation that diagonalizes the Hamiltonian using the ABR to\nsecond order. The work includes a discussion of the multiband WDF transport\nanalysis and the identification of the combined Zener-magnetic field induced\ntunneling.",
        "positive": "Coulomb impurity on a Dice lattice: atomic collapse and bound states: The modification of the quantum states in a Dice lattice due to a Coulomb\nimpurity are investigated. The energy band structure of a pristine Dice lattice\nconsists of a Dirac cone and a flat band at the Dirac point. We use the tight\nbinding formalism and find that the flat band states transform into a set of\ndiscrete bound states whose electron density is localized on a ring around the\nimpurity mainly on two of the three sublattices. The energy is proportional to\nthe strength of the Coulomb impurity. Beyond a critical strength of the Coulomb\npotential atomic collapse states appear that have some similarity with those\nfound in graphene with the difference that the flat band states contribute with\nan additional ring-like electron density that is spatially decoupled from the\natomic collapse part. At large value of the strength of the Coulomb impurity\nthe flat band bound states anti-cross with the atomic collapse states."
    },
    {
        "anchor": "Topological quantum criticality of the disordered Chern insulator: We consider the two-dimensional topological Chern insulator in the presence\nof static disorder. Generic quantum states in this system are Anderson\nlocalized. However, topology requires the presence of a subset of critical\nstates, with diverging localization length (the Chern insulator analog of the\n`center of the Landau band states' of the quantum Hall insulator.) We discuss\ngeometric criteria for the identification of these states at weak disorder, and\ntheir extension into the regime of strong disorder by analytical methods. In\nthis way, we chart a critical surface embedded in a phase space spanned by\nenergy, topological control parameter, and disorder strength. Our analytical\npredictions are supplemented by a numerical analysis of the position of the\ncritical states, and their multifractal properties.",
        "positive": "Impact of the dark path on quantum dot single photon emitters in small\n  cavities: Incoherent pumping in quantum dots (QDs) can create a biexciton state through\ntwo paths: via the formation of bright or dark exciton states. The latter,\ndark-pumping, path is shown to enhance the probability of two-photon\nsimultaneous emission, and hence increase $g^{(2)}(0)$ by a factor $\\propto\n1/\\gamma_S$, due to the slow spin relaxation rate $\\gamma_S$ in QDs. The\nexistence of the dark path is shown to impose a limitation on the single photon\n(SP) emission process, especially in nanocavities which exhibit a large\nexciton-cavity coupling and a Purcell enhancement for fast quantum\ntelecommunications."
    },
    {
        "anchor": "Enhancement of charged macromolecule capture by nanopores in a salt\n  gradient: Nanopores spanning synthetic membranes have been used as key components in\nproof-of-principle nanofluidic applications, particularly those involving\nmanipulation of biomolecules or sequencing of DNA. The only practical way of\nmanipulating charged macromolecules near nanopores is through a voltage\ndifference applied across the nanopore-spanning membrane. However, recent\nexperiments have shown that salt concentration gradients applied across\nnanopores can also dramatically enhance charged particle capture from a low\nconcentration reservoir of charged molecules at one end of the nanopore. This\npuzzling effect has hitherto eluded a physically consistent theoretical\nexplanation. Here, we propose an electrokinetic mechanism of this enhanced\ncapture that relies on the electrostatic potential near the pore mouth. For\nlong pores with diameter much greater than the local screening length, we\nobtain accurate analytic expressions showing how salt gradients control the\nlocal conductivity which can lead to increased local electrostatic potentials\nand charged analyte capture rates. We also find that the attractive\nelectrostatic potential may be balanced by an outward, repulsive electroosmotic\nflow (EOF) that can in certain cases conspire with the salt gradient to further\nenhance the analyte capture rate.",
        "positive": "Phaseless three-dimensional optical nano-imaging: We propose a method for optical nano-imaging in which the structure of a\nthree-dimensional inhomogeneous medium may be recovered from far-field power\nmeasurements. Neither phase control of the illuminating field nor phase\nmeasurements of the scattered field are necessary. The method is based on the\nsolution to the inverse scattering problem for a system consisting of a\nweakly-scattering dielectric sample and a strongly-scattering nano-particle\ntip. Numerical simulations are used to illustrate the results."
    },
    {
        "anchor": "Signatures of odd-frequency correlations in the Josephson current of\n  superconductor/ferromagnet hybrid junctions: Contacting a bilayer ferromagnet with a singlet even-frequency superconductor\nallows for the realization of an effective triplet odd-frequency\nsuperconductor. In this work, we investigate the Josephson effect between\nsuperconductors with different symmetries (e.g. odd- versus even-frequency). In\nparticular, we study the supercurrent flowing between two triplet odd-frequency\nsuperconducting leads through a weak singlet even-frequency superconductor. We\nshow that the peculiar temperature dependence of the critical current below the\nsuperconducting transition of the weak superconductor is a signature of the\ncompetition between odd/odd-frequency and odd/even-frequency Josephson\ncouplings.",
        "positive": "Majorana states and devices in magnetic structures: The pursuit for Majorana fermions is one of the top priorities in condensed\nmatter physics at the moment. In this work we propose a new method of\nfabricating Majorana Josephson devices in systems with a weak or no spin-orbit\ncoupling and without external magnetic fields. Our proposal is based on curved\nsemiconductor wires in the proximity of superconducting elements and a small\nnumber of nanomagnets. With this method it is possible to fabricate devices\nthat are not feasible by employing straight topological wire segments. The\nproposed method is naturally scalable and opens up a possibility for a\nsystematic fabrication of arrays of Majorana states where a pair of Majorana\nstates is obtained from a single magnet."
    },
    {
        "anchor": "Difference frequency generation of surface plasmon-polaritons in Landau\n  quantized graphene: We develop a rigorous quantum-mechanical theory of the nonlinear optical\nprocess of difference frequency generation of surface plasmon-polaritons in\nLandau-quantized graphene. Although forbidden in the electric-dipole\napproximation, the second-order susceptibility is surprisingly high, equivalent\nto the bulk magnitude above $10^{-3}$ m/V. We consider the graphene monolayer\nas a nonlinear optical component of a monolithic photonic chip with integrated\npump fields. The nonlinear power conversion efficiency of the order of tens\n$\\mu$W/W$^2$ is predicted from structures of $10-100$ $\\mu$m size. We\ninvestigate a variety of waveguide configurations to identify the optimal\ngeometry for maximum efficiency.",
        "positive": "Accelerate & Actualize: Can 2D Materials Bridge the Gap Between\n  Neuromorphic Hardware and the Human Brain?: Two-dimensional (2D) materials present an exciting opportunity for devices\nand systems beyond the von Neumann computing architecture paradigm due to their\ndiversity of electronic structure, physical properties, and atomically-thin,\nvan der Waals structures that enable ease of integration with conventional\nelectronic materials and silicon-based hardware. All major classes of\nnon-volatile memory (NVM) devices have been demonstrated using 2D materials,\nincluding their operation as synaptic devices for applications in neuromorphic\ncomputing hardware. Their atomically-thin structure, superior physical\nproperties, i.e., mechanical strength, electrical and thermal conductivity, as\nwell as gate-tunable electronic properties provide performance advantages and\nnovel functionality in NVM devices and systems. However, device performance and\nvariability as compared to incumbent materials and technology remain major\nconcerns for real applications. Ultimately, the progress of 2D materials as a\nnovel class of electronic materials and specifically their application in the\narea of neuromorphic electronics will depend on their scalable synthesis in\nthin-film form with desired crystal quality, defect density, and phase purity."
    },
    {
        "anchor": "Low voltage and time constant organic synapse-transistor: We report on an artificial synapse, an organic synapse-transistor (synapstor)\nworking at 1 volt and with a typical response time in the range 100-200 ms.\nThis device (also called NOMFET, Nanoparticle Organic Memory Field Effect\nTransistor) combines a memory and a transistor effect in a single device. We\ndemonstrate that short-term plasticity (STP), a typical synaptic behavior, is\nobserved when stimulating the device with input spikes of 1 volt. Both\nsignificant facilitating and depressing behaviors of this artificial synapse\nare observed with a relative amplitude of about 50% and a dynamic response <\n200 ms. From a series of in-situ experiments, i.e. measuring the\ncurrent-voltage characteristic curves in-situ and in real time, during the\ngrowth of the pentacene over a network of gold nanoparticles, we elucidate\nthese results by analyzing the relationship between the organic film morphology\nand the transport properties. This synapstor works at a low energy of about 2\nnJ/spike. We discuss the implications of these results for the development of\nneuro-inspired computing architectures and interfacing with biological neurons.",
        "positive": "Monte Carlo studies of the properties of the Majorana quantum error\n  correction code: is self-correction possible during braiding?: The Majorana code is an example of a stabilizer code where the quantum\ninformation is stored in a system supporting well-separated Majorana Bound\nStates (MBSs). We focus on one-dimensional realizations of the Majorana code,\nas well as networks of such structures, and investigate their lifetime when\ncoupled to a parity-preserving thermal environment. We apply the Davies\nprescription, a standard method that describes the basic aspects of a thermal\nenvironment, and derive a master equation in the Born-Markov limit. We first\nfocus on a single wire with immobile MBSs and perform error correction to\nannihilate thermal excitations. In the high-temperature limit, we show both\nanalytically and numerically that the lifetime of the Majorana qubit grows\nlogarithmically with the size of the wire. We then study a trijunction with\nfour MBSs when braiding is executed. We study the occurrence of dangerous error\nprocesses that prevent the lifetime of the Majorana code from growing with the\nsize of the trijunction. The origin of the dangerous processes is the braiding\nitself, which separates pairs of excitations and renders the noise nonlocal;\nthese processes arise from the basic constraints of moving MBSs in 1D\nstructures. We confirm our predictions with Monte Carlo simulations in the\nlow-temperature regime, i.e. the regime of practical relevance. Our results put\na restriction on the degree of self-correction of this particular 1D\ntopological quantum computing architecture."
    },
    {
        "anchor": "Spin polarization in a T-shape conductor induced by strong Rashba\n  spin-orbit coupling: We investigate numerically the spin polarization of the current in the\npresence of Rashba spin-orbit interaction in a T-shaped conductor proposed by\nA.A. Kiselev and K.W. Kim (Appl. Phys. Lett. {\\bf 78} 775 (2001)). The\nrecursive Green function method is used to calculate the three terminal spin\ndependent transmission probabilities. We focus on single-channel transport and\nshow that the spin polarization becomes nearly 100 % with a conductance close\nto $e^{2}/h$ for sufficiently strong spin-orbit coupling. This is interpreted\nby the fact that electrons with opposite spin states are deflected into an\nopposite terminal by the spin dependent Lorentz force. The influence of the\ndisorder on the predicted effect is also discussed. Cases for multi-channel\ntransport are studied in connection with experiments.",
        "positive": "Statistics of resonances and of delay times in quasiperiodic\n  Schr\"odinger equations: We study the statistical distributions of the resonance widths ${\\cal P}\n(\\Gamma)$, and of delay times ${\\cal P} (\\tau)$ in one dimensional\nquasi-periodic tight-binding systems with one open channel. Both quantities are\nfound to decay algebraically as $\\Gamma^{-\\alpha}$, and $\\tau^{-\\gamma}$ on\nsmall and large scales respectively. The exponents $\\alpha$, and $\\gamma$ are\nrelated to the fractal dimension $D_0^E$ of the spectrum of the closed system\nas $\\alpha=1+D_0^E$ and $\\gamma=2-D_0^E$. Our results are verified for the\nHarper model at the metal-insulator transition and for Fibonacci lattices."
    },
    {
        "anchor": "Detection of interactions via generalized factorial cumulants in systems\n  in and out of equilibrium: We introduce time-dependent, generalized factorial cumulants $C_s^m(t)$ of\nthe full counting statistics of electron transfer as a tool to detect\ninteractions in nanostructures. The violation of the sign criterion $(-1)^{m-1}\nC^m_s(t)\\ge0$ for \\emph{any} time $t$, order $m$, and parameter $s$ proves the\npresence of interactions. For given system parameters, there is a minimal time\nspan $t_\\text{min}$ and a minimal order $m$ to observe the violation of the\nsign criterion. We demonstrate that generalized factorial cumulants are more\nsensitive to interactions than ordinary ones and can detect interactions even\nin regimes where ordinary factorial cumulants fail. We illustrate our findings\nwith the example of a quantum dot tunnel coupled to electronic reservoirs\neither in or out of equilibrium.",
        "positive": "Spin-Orbit-Induced Topological Flat Bands in Line and Split Graphs of\n  Bipartite Lattices: Topological flat bands, such as the band in twisted bilayer graphene, are\nbecoming a promising platform to study topics such as correlation physics,\nsuperconductivity, and transport. In this work, we introduce a generic approach\nto construct two-dimensional (2D) topological quasi-flat bands from line graphs\nand split graphs of bipartite lattices. A line graph or split graph of a\nbipartite lattice exhibits a set of flat bands and a set of dispersive bands.\nThe flat band connects to the dispersive bands through a degenerate state at\nsome momentum. We find that, with spin-orbit coupling (SOC), the flat band\nbecomes quasi-flat and gapped from the dispersive bands. By studying a series\nof specific line graphs and split graphs of bipartite lattices, we find that\n(i) if the flat band (without SOC) has inversion or $C_2$ symmetry and is\nnon-degenerate, then the resulting quasi-flat band must be topologically\nnontrivial, and (ii) if the flat band (without SOC) is degenerate, then there\nexists an SOC potential such that the resulting quasi-flat band is\ntopologically nontrivial. This generic mechanism serves as a paradigm for\nfinding topological quasi-flat bands in 2D crystalline materials and\nmeta-materials."
    },
    {
        "anchor": "Spin-orbit coupling in a Quantum Dot at high magnetic field: We describe the simultaneous effects of the spin-orbit (SO) perturbation and\na magnetic field $B$ on a disk shaped quantum dot (QD). {As it is known the}\ncombination of electrostatic forces among the $N$ electrons confined in the QD\nand the Pauli principle can induce a spin polarization when $B$ (applied in the\ndirection orthogonal to the QD) is above a threshold value. In the presence of\nan electric field parallel to $B$, coupled to the spin $ S $ by a Rashba term,\nwe demonstrate that a symmetry breaking takes place: we can observe it by\nanalyzing the splitting of the levels belonging to an unperturbed multiplet. We\nalso discuss the competitive effects of the magnetic field, the SO perturbation\nand the electron electron interaction, in order to define the hierarchy of the\nstates belonging to a multiplet. We demonstrate how this hierarchy depends on\nthe QD's size. We show the spin texture due to the combined effects of the\nRashba effect and the interaction responsible for the polarization.",
        "positive": "Photonic Hall effect in cold atomic clouds: On the basis of exact numerical simulations and analytical calculations, we\ndescribe qualitatively and quantitatively the interference processes at the\norigin of the photonic Hall effect for resonant Rayleigh (point-dipole)\nscatterers in a magnetic field. For resonant incoming light, the induced giant\nmagneto-optical effects result in relative Hall currents in the percent range,\nthree orders of magnitude larger than with classical scatterers. This suggests\nthat the observation of the photonic Hall effect in cold atomic vapors is\nwithin experimental reach."
    },
    {
        "anchor": "Graphene Nanoribbons Under Axial Compressive and Point Tensile Stresses: The geometric, electronic and magnetic properties of strained graphene\nnanoribbons were investigated using spin polarized calculations within the\nframework of density functional theory. Cases of compressive stress along the\nlonger axis of a nanoribbon and tensile stress at the midpoint and\nperpendicular to the plane of the nanoribbon were considered. Significant\nstructural changes were observed including the formation of nanoripples. The\ncalculated electronic and magnetic properties strongly depend on the size and\nshape of nanoribbons. The tunable magnetic properties of strained nanoribbons\ncan be employed for designing magnetic nano-switches.",
        "positive": "Spatially-resolved luminescence and crystal structure of single\n  core-shell nanowires measured in the as-grown geometry: We report on the direct correlation between the structural and optical\nproperties of single, as-grown core-multi-shell\nGaAs/In$_{0.15}$Ga$_{0.85}$As/GaAs/AlAs/GaAs nanowires. Fabricated by molecular\nbeam epitaxy on a pre-patterned Si(111) substrate, on a row of well separated\nnucleation sites, it was possible to access individual nanowires in the\nas-grown geometry. The polytype distribution along the growth axis of the\nnanowires was revealed by synchrotron-based nanoprobe X-ray diffraction\ntechniques monitoring the axial 111 Bragg reflection. For the same nanowires,\nthe spatially-resolved emission properties were obtained by cathodoluminescence\nhyperspectral linescans in a scanning electron microscope. Correlating both\nmeasurements, we reveal a blueshift of the shell quantum well emission energy\ncombined with an increased emission intensity for segments exhibiting a mixed\nstructure of alternating wurtzite and zincblende stacking compared with the\npure crystal polytypes. The presence of this mixed structure was independently\nconfirmed by cross-sectional transmission electron microscopy."
    },
    {
        "anchor": "Nano-corrugation induced forces between electrically neutral plasmonic\n  objects: Recent advances in nanotechnology have created tremendous excitement across\ndifferent disciplines but in order to fully control and manipulate nano-scale\nobjects, we must understand the forces at work at the nano-scale, which can be\nvery different from those that dominate the macro-scale. We show that there is\na new kind of curvature-induced force that acts between nano-corrugated\nelectrically neutral plasmonic surfaces. Absent in flat surfaces, such a force\nowes its existence entirely to geometric curvature, and originates from the\nkinetic energy associated with the electron density which tends to make the\nprofile of the electron density smoother than that of the ionic background and\nhence induces curvature-induced local charges. Such a force cannot be found\nusing standard classical electromagnetic approaches, and we use a\nself-consistent hydrodynamics model as well as first principles density\nfunctional calculations to explore the character of such forces. These two\nmethods give qualitative similar results. We found that the force can be\nattractive or repulsive, depending on the details of the nano-corrugation, and\nits magnitude is comparable to light induced forces acting on plasmonic\nnano-objects.",
        "positive": "Tunable Coulomb blockade in nanostructured graphene: We report on Coulomb blockade and Coulomb diamond measurements on an etched,\ntunable single-layer graphene quantum dot. The device consisting of a graphene\nisland connected via two narrow graphene constrictions is fully tunable by\nthree lateral graphene gates. Coulomb blockade resonances are observed and from\nCoulomb diamond measurements a charging energy of ~3.5 meV is extracted. For\nincreasing temperatures we detect a peak broadening and a transmission increase\nof the nanostructured graphene barriers."
    },
    {
        "anchor": "Spin injection via (110)-grown semiconductor barriers: We study the tunneling of conduction electrons through a (110)-oriented\nsingle-barrier heterostructure grown from III-V semiconductor compounds. It is\nshown that, due to low spatial symmetry of such a barrier, the tunneling\ncurrent through the barrier leads to an electron spin polarization. The inverse\neffect, generation of a direct tunneling current by spin polarized electrons,\nis also predicted. We develop the microscopic theory of the effects and show\nthat the spin polarization emerges due to the combined action of the\nDresselhaus spin-orbit coupling within the barrier and the Rashba spin-orbit\ncoupling at the barrier interfaces.",
        "positive": "Hybrid magneto-dynamical modes in a single magnetostrictive nanomagnet\n  on a piezoelectric substrate arising from magneto-elastic modulation of\n  precessional dynamics: Magneto-elastic (or \"straintronic\") switching has emerged as an extremely\nenergy-efficient mechanism for switching the magnetization of magnetostrictive\nnanomagnets in magnetic memory, logic and non-Boolean circuits. Here, we\ninvestigate the ultrafast magneto-dynamics associated with straintronic\nswitching in a single quasi-elliptical magnetostrictive Co nanomagnet deposited\non a piezoelectric PMN-PT substrate using time-resolved magneto-optical Kerr\neffect (TR-MOKE) measurements. The pulsed laser pump beam in the TR-MOKE plays\na dual role: it causes precession of the nanomagnet's magnetization about an\napplied bias magnetic field and it also generates surface acoustic waves (SAWs)\nin the piezoelectric substrate that produce periodic strains in the\nmagnetostrictive nanomagnet and modulate the precessional dynamics. This\nmodulation gives rise to intriguing hybrid magneto-dynamical modes in the\nnanomagnet, with rich spin wave texture. The characteristic frequencies of\nthese modes are 5-15 GHz, indicating that strain can affect magnetization in a\nmagnetostrictive nanomagnet in time scales much smaller than 1 ns (~100 ps).\nThis can enable ~10 GHz-range magneto-elastic nano-oscillators that are\nactuated by strain instead of a spin-polarized current, as well as ultrafast\nmagneto-electric generation of spin waves for magnonic logic circuits,\nholograms, etc."
    },
    {
        "anchor": "Dynamic magnetic susceptibility and electrical detection of\n  ferromagnetic resonance: The dynamic magnetic susceptibility of magnetic materials near ferromagnetic\nresonance (FMR) is very important in interpreting dc-voltage in electrical\ndetection of FMR. Based on the causality principle and the assumption that the\nusual microwave absorption lineshape around FMR is Lorentzian, general forms of\ndynamic susceptibility of an arbitrary sample and the corresponding dc-voltage\nlineshape are obtained. Our main findings are: 1) The dynamic susceptibility is\nnot a Polder tensor for material with arbitrary anisotropy. Two off-diagonal\nelements are not in general opposite to each other. However, the linear\nresponse coefficient of magnetization to total rf field is a Polder tensor.\nThis may explain why two off-diagonal elements are always assumed to be\nopposite to each other in analyses. 2) The frequency dependence of dynamic\nsusceptibility near FMR is fully characterized by six numbers while its field\ndependence is fully characterized by seven numbers. 3) A recipe of how to\ndetermine these numbers by standard microwave absorption measurements for an\narbitrary sample is proposed. Our results allow one to unambiguously separate\nthe contribution of the anisotropic magnetoresistance to dc-voltage from that\nof the anomalous Hall effect. With these results, one can reliably extract the\ninformation of spin pumping and the inverse spin Hall effect, and determine the\nspin-Hall angle. 4) The field-dependence of susceptibility matrix at a fixed\nfrequency may have several peaks when the effective field is not monotonic of\nthe applied field. In contrast, the frequency-dependence of susceptibility\nmatrix at a fixed field has only one peak. Furthermore, in the case that\nresonance frequency is not sensitive to the applied field, the field dependence\nof susceptibility matrix, as well as dc-voltage, may have another non-resonance\nbroad peak. Thus, one should be careful in interpreting observed peaks.",
        "positive": "First-principles many-body calculations of electronic conduction in\n  thiol- and amine-linked molecules: The electronic conductance of a benzene molecule connected to gold electrodes\nvia thiol, thiolate, and amino anchoring groups is calculated using\nnonequilibrium Green functions in combination with the fully selfconsistent GW\napproximation. The calculated conductance of benzenedithiol and benzenediamine\nis five times lower than predicted by standard density functional theory (DFT)\nin very good agreement with experiments. In contrast, the widely studied\nbenzenedithiolate structure is found to have a significantly higher conductance\ndue to the unsaturated sulfur bonds. These findings suggest that more complex\ngold/thiolate structures where the thiolate anchors are chemically passivated\nby Au adatoms are responsible for the measured conductance. Analysis of the\nenergy level alignment obtained with DFT, Hartree-Fock and GW reveals the\nimportance of self-interaction corrections (exchange) on the molecule and\ndynamical screening at the metal-molecule interface. The main effect of the GW\nself-energy is to renormalize the level positions, however, its influence on\nthe shape of molecular resonances also affects the conductance.\nNon-selfconsistent G0W0 calculations, starting from either DFT or Hartree-Fock,\nyield conductance values within 50% of the selfconsistent GW results."
    },
    {
        "anchor": "Magnetic force sensing using a self-assembled nanowire: We present a scanning magnetic force sensor based on an individual\nmagnet-tipped GaAs nanowire (NW) grown by molecular beam epitaxy. Its magnetic\ntip consists of a final segment of single-crystal MnAs formed by sequential\ncrystallization of the liquid Ga catalyst droplet. We characterize the\nmechanical and magnetic properties of such NWs by measuring their flexural\nmechanical response in an applied magnetic field. Comparison with numerical\nsimulations allows the identification of their equilibrium magnetization\nconfigurations, which in some cases include magnetic vortices. To determine a\nNW's performance as a magnetic scanning probe, we measure its response to the\nfield profile of a lithographically patterned current-carrying wire. The NWs'\ntiny tips and their high force sensitivity make them promising for imaging weak\nmagnetic field patterns on the nanometer-scale, as required for mapping\nmesoscopic transport and spin textures or in nanometer-scale magnetic\nresonance.",
        "positive": "Low-Frequency Noise in Quasi-1D (TaSe$_4$)$_2$I Weyl Semimetal\n  Nanoribbons: We report on low-frequency current fluctuations, i.e. electronic noise, in\nquasi-one-dimensional (TaSe$_4$)$_2$I Weyl semimetal nanoribbons. It was found\nthat the noise spectral density is of the 1/f type and scales with the square\nof the current, S~I^2 (f is the frequency). The noise spectral density\nincreases by almost an order of magnitude and develops Lorentzian features near\nthe temperature T~225 K. These spectral changes were attributed to the\ncharge-density-wave phase transition even though the temperature of the noise\nmaximum deviates from the reported Peierls transition temperature in bulk\n(TaSe$_4$)$_2$I crystals. The noise level, normalized by the channel area, in\nthese Weyl semimetal nanoribbons was surprisingly low, $\\sim 10^{-9}$\num$^2$Hz$^{-1}$ at f=10 Hz, when measured below and above the Peierls\ntransition temperature. Obtained results shed light on the specifics of\nelectron transport in quasi-1D topological Weyl semimetals and can be important\nfor their proposed applications as downscaled interconnects."
    },
    {
        "anchor": "Toward CL-20 crystalline covalent solids: On the dependence of energy\n  and electronic properties on the effective size of CL-20 chains: One-dimensional CL-20 chains have been constructed using CH$_2$ molecular\nbridges for the covalent bonding between isolated CL-20 fragments. The energy\nand electronic properties of the nanostructures obtained have been analyzed by\nmeans of density functional theory and nonorthogonal tight-binding model\nconsidering Landauer-B\\\"uttiker formalism. It has been found that such systems\nbecome more thermodynamically stable as the efficient length of the chain\nincreases. Thus, the formation of bulk covalent CL-20 solids may be\nenergetically favorable, and such structures may possess high kinetic stability\ncomparing to the CL-20 molecular crystals. As for electronic properties of pure\nCL-20 chains, they are wide-bandgap semiconductors with energy gaps equal to\nseveral electron volts that makes their use in nanoelectronic applications\nproblematic without any additional modification.",
        "positive": "Floquet Semimetal with Floquet-band Holonomy: Exotic topological states of matter such as Floquet topological insulator or\nFloquet Weyl semimetal can be induced by periodic driving. This work proposes a\nFloquet semimetal with Floquet-band holonomy. That is, the system is gapless,\nbut as a periodic parameter viewed as quasimomentum of a synthetic dimension\ncompletes an adiabatic cycle, each Floquet band as a whole exchanges with other\nFloquet bands. The dynamical manifestations of such Floquet-band holonomy are\nstudied. Under open boundary conditions, we discover anomalous chiral edge\nmodes localized only at one edge, winding around the entire quasienergy\nBrillouin zone, well separated from bulk states, and possessing holonomy\ndifferent from bulk states. These remarkable properties are further exploited\nto realize quantized or half-quantized edge state pumping."
    },
    {
        "anchor": "Spin and charge dynamics in [TbPc$_2$]$^0$ and [DyPc$_2$]$^0$ single\n  molecule magnets: Magnetization, AC susceptibility and $\\mu$SR measurements have been performed\nin neutral phthalocyaninato lanthanide ([LnPc$_2]^0$) single molecule magnets\nin order to determine the low-energy levels structure and to compare the\nlow-frequency spin excitations probed by means of macroscopic techniques, such\nas AC susceptibility, with the ones explored by means of techniques of\nmicroscopic character, such as $\\mu$SR. Both techniques show a high temperature\nthermally activated regime for the spin dynamics and a low temperature\ntunneling one. While in the activated regime the correlation times for the spin\nfluctuations estimated by AC susceptibility and $\\mu$SR basically agree, clear\ndiscrepancies are found in the tunneling regime. In particular, $\\mu$SR probes\na faster dynamics with respect to AC susceptibility. It is argued that the\ntunneling dynamics probed by $\\mu$SR involves fluctuations which do not yield a\nnet change in the macroscopic magnetization probed by AC susceptibiliy. Finally\nresistivity measurements in [TbPc$_2]^0$ crystals show a high temperature\nnearly metallic behaviour and a low temperature activated behaviour.",
        "positive": "Nano-ploughed Josephson Junctions as on-chip Radiation Sources: A new technique is presented which enables the fabrication of highly\ntransparent Josephson junctions in combination with mesoscopic devices. We\nutilize a modified AFM tip to plough grooves into superconducting material,\nthus defining a weak link. This weak link is made within the superconducting\nsplit-gates, which are used to electrostatically form a conventional quantum\ndot and serves as a source of millimeter wave radiation around 100 GHz. We show\nthe characteristics of typical junctions built and discuss their high-frequency\nproperties. We find that the millimeter wave emission of the weak link leads to\na bolometric effect in the case of quantum point contact spectroscopy."
    },
    {
        "anchor": "Dispersive readout of a silicon quantum dot with an accumulation-mode\n  gate sensor: Sensitive charge detection has enabled qubit readout in solid-state systems.\nRecently, an alternative to the well-established charge detection via on-chip\nelectrometers has emerged, based on in situ gate detectors and radio-frequency\ndispersive readout techniques. This approach promises to facilitate scalability\nby removing the need for additional device components devoted to sensing. Here,\nwe perform gate-based dispersive readout of an accumulation-mode silicon\nquantum dot. We observe that the response of an accumulation-mode gate detector\nis significantly affected by its bias voltage, particularly if this exceeds the\nthreshold for electron accumulation. We discuss and explain these results in\nlight of the competing capacitive contributions to the dispersive response.",
        "positive": "Inverse Spin Hall Effect and Anomalous Hall Effect in a Two-Dimensional\n  Electron Gas: We study the coupled dynamics of spin and charge currents in a\ntwo-dimensional electron gas in the transport diffusive regime. For systems\nwith inversion symmetry there are established relations between the spin Hall\neffect, the anomalous Hall effect and the inverse spin Hall effect. However, in\ntwo-dimensional electron gases of semiconductors like GaAs, inversion symmetry\nis broken so that the standard arguments do not apply. We demonstrate that in\nthe presence of a Rashba type of spin-orbit coupling (broken structural\ninversion symmetry) the anomalous Hall effect, the spin Hall and inverse spin\nHall effect are substantially different effects. Furthermore we discuss the\ninverse spin Hall effect for a two-dimensional electron gas with Rashba and\nDresselhaus spin-orbit coupling; our results agree with a recent experiment."
    },
    {
        "anchor": "Detection of a Majorana-fermion zero mode by a T-shaped quantum-dot\n  structure: Electron transport through the T-shaped quantum-dot (QD) structure is\ntheoretically investigated, by considering a Majorana zero mode coupled to the\nterminal QD. It is found that in the double-QD case, the presence of the\nMajorana zero mode can efficiently dissolve the antiresonance point in the\nconductance spectrum and induce a conductance peak to appear at the same energy\nposition whose value is equal to $e^2/2h$. This antiresonance-resonance change\nwill be suitable to detect the Majorana bound states. Next in the multi-QD\ncase, we observe that in the zero-bias limit, the conductances are always the\nsame as the double-QD result, independent of the parity of the QD number. We\nbelieve that all these results can be helpful for understanding the properties\nof Majorana bound states.",
        "positive": "Greater than 5 Percent Compressive Strain in Graphene via the Self\n  Rolled up Membrane Platform: Graphene is an atomically thin metallic membrane capable of sustaining\nreversible strain and offers a tempting prospect of controlling its\noptoelectronic properties via strain. Graphenes exceptional mechanical\nflexibility and tensile strength provide a lot of room for strain engineering.\nHere we use the self-rolled-up membrane platform for strain engineering and\nintegration of graphene with stressed dielectric thin films. Graphene rolls up\nor down together with the stressed film upon releasing from the substrate and\nthe curvature of the rolled-up film stack enables the strain tuning of the\ngraphene monolayer. Raman spectroscopy was used to characterize the uniaxial\nstrain in rolled up graphene by quantifying the red shift and splitting of the\nG peak in the doubly degenerate E2g optical mode. Approximately 5 percent\ncompressive strain is realized using a SRuM diameter of roughly 2 microns. By\nreducing the diameter of the SRuM structure, even higher strain level can be\nreached. The SRuM approach can also be readily applied to induce strain in\nother materials beyond the level that can be achieved using conventional\napproaches."
    },
    {
        "anchor": "Heat transport as torsional responses and Keldysh formalism in a curved\n  spacetime: We revisit a theory of heat transport in the light of a gauge theory of\ngravity and find the proper heat current with a corresponding gauge field,\nwhich yields the natural definitions of the heat magnetization and the\nKubo-formula contribution to the thermal conductivity as torsional responses.\nWe also develop a general framework for calculating gravitational responses by\ncombining the Keldysh and Cartan formalisms. By using this framework, we\nexplicitly calculate these two quantities and reproduce the Wiedemann-Franz law\nfor the thermal Hall conductivity in the clean and non-interacting case.\nFinally, we discuss an effective action for the quantized thermal Hall effect\nin $(2 + 1)$-D topological superconductors.",
        "positive": "Energy levels in a single-electron quantum dot with hydrostatic pressure: In this article we present a study of the effects of hydrostatic pressure on\nthe energy levels of a quantum dot with an electron. A quantum dot is modeled\nusing an infinite potential well and a two-dimensional harmonic oscillator and\nsolved through the formalism of second quantization. A scheme for the\nimplementation of a quantum NOT gate controlled with hydrostatic pressure is\nproposed."
    },
    {
        "anchor": "Counting Pseudo Landau Levels in Spatially Modulated Dirac Systems: In a system with Dirac cones, spatial modulation in material parameters\ninduces a pseudo magnetic field, which acts like an external magnetic field.\nHere, we derive a concise formula to count the pseudo Landau levels in the\nsimplest setup for having a pseudo magnetic field. The formula is so concise\nthat it is helpful in seeing the essence of the phenomenon, and in considering\nthe experimental design for the pseudo magnetic field. Furthermore, it is\nrevealed that anisotropic Dirac cones are advantageous in pseudo Landau level\nformation in general. The proposed setup is relatively easy to be realized by\nspatial modulation in the chemical composition, and we perform an estimation of\nthe pseudo magnetic field in an existing material (an antiperovskite material),\nby following the composition dependence with the help of the ab-initio method.",
        "positive": "Anatomy of linear and non-linear intermolecular exchange in S = 1\n  nanographenes: Nanographene triangulenes with a S = 1 ground state have been used as\nbuilding blocks of antiferromagnetic Haldane spin chains realizing a symmetry\nprotected topological phase. By means of inelastic electron spectroscopy, it\nwas found that the intermolecular exchange contains both linear and non-linear\ninteractions, realizing the bilinear-biquadratic Hamiltonian. Starting from a\nHubbard model, and mapping it to an interacting Creutz ladder, we analytically\nderive these effective spin-interactions using perturbation theory, up to\nfourth order. We find that for chains with more than two units other\ninteractions arise, with same order-of-magnitude strength, that entail second\nneighbor linear, and three-site non-linear exchange. Our analytical expressions\ncompare well with experimental and numerical results. We discuss the extension\nto general S = 1 molecules, and give numerical results for the strength of the\nnon-linear exchange for several nanographenes. Our results pave the way towards\nrational design of spin Hamiltonians for nanographene based spin chains."
    },
    {
        "anchor": "Gas Sensing with h-BN Capped MoS2 Heterostructure Thin Film Transistors: We have demonstrated selective gas sensing with molybdenum disulfide (MoS2)\nthin films transistors capped with a thin layer of hexagonal boron nitride\n(h-BN). The resistance change was used as a sensing parameter to detect\nchemical vapors such as ethanol, acetonitrile, toluene, chloroform and\nmethanol. It was found that h-BN dielectric passivation layer does not prevent\ngas detection via changes in the source-drain current in the active MoS2 thin\nfilm channel. The use of h-BN cap layers (thickness H=10 nm) in the design of\nMoS2 thin film gas sensors improves device stability and prevents device\ndegradation due to environmental and chemical exposure. The obtained results\nare important for applications of van der Waals materials in chemical and\nbiological sensing.",
        "positive": "Thermoelectric detection of ferromagnetic resonance of a nanoscale\n  ferromagnet: We present thermoelectric measurements of the heat dissipated due to\nferromagnetic resonance of a Permalloy strip. A microwave magnetic field,\nproduced by an on-chip coplanar strip waveguide, is used to drive the\nmagnetization precession. The generated heat is detected via Seebeck\nmeasurements on a thermocouple connected to the ferromagnet. The observed\nresonance peak shape is in agreement with the Landau-Lifshitz-Gilbert equation\nand is compared with thermoelectric finite element modeling. Unlike other\nmethods, this technique is not restricted to electrically conductive media and\nis therefore also applicable to for instance ferromagnetic insulators."
    },
    {
        "anchor": "Quantum energy flow, dissipation and decoherence in mesoscopic\n  dielectric structures: We first present a summary of recent results concerning the phononic energy\ntransport properties of mesoscopic, suspended dielectric wires. We then discuss\nsome related open problems concerning the fundamental lower limits on the\nvibrational damping rates of submicron-sized cantilever structures and also the\npossibility to create and detect quantum superpositions of spatially separated\nstates for such structures.",
        "positive": "Relativistic Drude Response of Photoexcited Dirac Quasiparticles in\n  Graphene: Graphene, a monolayer of carbon atoms arranged in a hexagonal pattern,\nprovides a unique two-dimensional (2D) system exhibiting exotic phenomena such\nas quantum Hall effects, massless Dirac quasiparticle excitations and universal\nabsorption & conductivity. The linear energy-momentum dispersion relation in\ngraphene also offers the opportunity to mimic the physics of far-away\nrelativistic particles like neutron stars and white dwarfs. In this letter, we\nperform a counterintuitive ultrafast pump-probe experiment with high photon\nenergies to isolate the Drude-like intraband dynamics of photoexcited carriers.\nWe directly demonstrate the relativistic nature of the photoexcited Dirac\nquasiparticles by observing a nonlinear scaling of the response with the\ndensity of photoexcited carriers. This is in striking contrast to the linear\nscaling that is usually observed in conventional materials. Our results also\nindicate strong electron-phonon coupling in graphene, leading to a sub-100\nfemtosecond thermalization between high energy photoexcited carriers and\noptical phonons."
    },
    {
        "anchor": "A Phenomenological Model for the Quantum Capacitance of Monolayer and\n  Bilayer Graphene Devices: Graphene nanostructures exhibit an intrinsic advantage in relation to the\ngate delay in three-terminal devices and provide additional benefits when\noperate in the quantum capacitance limit. In this paper, we developed a simple\nmodel that captures the Fermi energy and temperature dependence of the quantum\ncapacitance for monolayer and bilayer graphene devices. Quantum capacitance is\ncalculated from the broadened density of states taking into account\nelectron-hole puddles and possible finite lifetime of electronic states through\na Gaussian broadening distribution. The obtained results are in agreement with\nmany features recently observed in quantum capacitance measurements on both\ngated monolayer and bilayer graphene devices. The temperature dependence of the\nminimum quantum capacitance around the charge neutrality point is also\ninvestigated.",
        "positive": "Excitons without effective mass: biased bilayer graphene: Understanding the dynamics of excitons in two dimensional semiconductors\nrequires a theory that incorporates the essential physics distinct from their\nthree-dimensional counterparts. In addition to the modified dielectric\nenvironment, single-particle states with strongly non-parabolic dispersion\nappear in many two-dimensional band structures, so that \"effective mass\" is\nill-defined. Focusing on electrostatically-biased bilayer graphene as an\nexample where quartic (and higher) dispersion terms are necessary, we present a\nsemi-analytic theory used to investigate the properties of ground and excited\nexcitonic states. This includes determination of relative oscillator strengths\nand magnetic moments (g-factors) which can be directly compared to recent\nexperimental measurements."
    },
    {
        "anchor": "The role of virtual photons in quantum tunneling: Quantum tunneling, a phenomenon which has no counterpart in classical\nphysics, is the quantum-mechanical process by which a microscopic particle can\ntransition through a potential barrier even when the energy of the incident\nparticle is lower than the height of the potential barrier. In this work, a\nmechanism based on electron/positron annihilation and creation with the\nparticipation of virtual photons is proposed as an alternative to explain\nquantum tunneling processes.",
        "positive": "Spin-orbit interaction and weak localization in heterostructures: Theory of weak localization in two-dimensional high-mobility semiconductor\nsystems is developed with allowance for the spin-orbit interaction. The\nobtained expressions for anomalous magnetoresistance are valid in the whole\nrange of classically weak magnetic fields and for arbitrary strengths of bulk\nand structural inversion asymmetry contributions to the spin splitting. The\ntheory serves for both diffusive and ballistic regimes of electron propagation\ntaking into account coherent backscattering and nonbackscattering processes.\nThe transition between weak localization and antilocalization regimes is\nanalyzed. The manifestation of the mutual compensation of Rashba and\nDresselhaus spin splittings in magnetoresistance is discussed. Perfect\ndescription of experimental data on anomalous magnetoresistance in\nhigh-mobility heterostructures is demonstrated. The in-plane magnetic field\ndependence of the conductivity caused by an interplay of the spin-orbit\nsplittings and Zeeman effect is described theoretically."
    },
    {
        "anchor": "Hole subband mixing and polarization of luminescence from quantum\n  dashes: a simple model: In this paper, we address the problem of luminescence polarization in the\ncase of nanostructures characterized by an in-plane shape asymmetry. We develop\na simple semi-qualitative model revealing the mechanism that accounts for the\nselective polarization properties of such structures. It shows that they are\nnot a straightforward consequence of the geometry but are related to it via\nvalence subband mixing. Our model allows us to predict the degree of\npolarization (DOP) dependence on the in-plane dimensions of investigated\nstructures assuming a predominantly heavy hole character of the valence band\nstates, simplifying the shape of confining potential and neglecting the\ninfluence of the out-of plane dimension. The energy dependence modeling reveals\nthe importance of different excited states in subsequent spectral ranges\nleading to non-monotonic character of the DOP. The modeling results show good\nagreement with the experimental data for an ensemble of InAs/InP quantum dashes\nfor a set of realistc parameters with the heavy-light hole states separation\nbeing the only adjustable one. All characteristic features are reproduced in\nthe framework of the proposed model and their origin can be well explained and\nunderstood. We also make some further predictions about the influence of both\nthe internal characteristics of the nanostructures (e.g. height) and the\nexternal conditions (excitation power, temperature) on the overall DOP.",
        "positive": "A Theoretical Paradigm for Thermal Rectification via Phonon Filtering\n  and Energy Carrier Confinement: We provide a theoretical framework for the development of a solid-state\nthermal rectifier through a confinement in the available population of phonons\non one side of an asymmetrically graded film stack. Using a modification of the\nphonon gas model to account for phonon filtering and population confinement, we\ndemonstrate that for an ideal material, with low phonon anharmonicity,\nsignificant thermal rectification can be achieved even in the absence of\nballistic phonon transport. This formalism is used to illustrate thermal\nrectification in a thin-film of diamond (1-5 nm) graded to dimensions > 1\n{\\mu}m exhibiting theoretical values of thermal rectification ratios between\n0.75 and 6. Our theoretical formulation for thermal rectification is therefore\nexpected to produce opportunities to design advanced solid-state devices that\nenable a variety of critical technologies."
    },
    {
        "anchor": "Discontinuities in the level density of small quantum dots under strong\n  magnetic fields: Exact diagonalization studies of the level density in a six-electron quantum\ndot under magnetic fields around 7 T (``filling factor'' around 1/2) are\nreported. In any spin-polarization channel, two regimes are visible in the dot\nexcitation spectrum: one corresponding to interacting quasiparticles (i.e.\ncomposite fermions) for excitation energies below 0.4 meV, and a second one for\nenergies above 0.4 meV, in which the level density (exponentially) increases at\nthe same rate as in the non-interacting composite-fermion model.",
        "positive": "Theory of high bias Coulomb Blockade in ultrashort molecules: We point out that single electron charging effects such as Coulomb Blockade\n(CB) and high-bias staircases play a crucial role in transport through single\nultrashort molecules. A treatment of Coulomb Blockade through a prototypical\nmolecule, benzene, is developed using a master-equation in its complete\nmany-electron Fock space, evaluated through exact diagonalization or full\nConfiguration Interaction (CI). This approach can explain a whole class of\nnon-trivial experimental features including vanishing zero bias conductances,\nsharp current onsets followed by ohmic current rises, and gateable current\nlevels and conductance structures, most of which cannot be captured even\nqualitatively within the traditional Self Consistent Field (SCF) approach\ncoupled with perturbative transport theories. By comparing the two approaches,\nnamely SCF and CB, in the limit of weak coupling to the electrode, we establish\nthat the inclusion of strong-correlations within the molecule becomes critical\nin addressing the above experiments. Our approach includes\non-bridge-correlations fully, and is therefore well-suited for describing\ntransport through short molecules in the limit of weak coupling to electrodes."
    },
    {
        "anchor": "Strong and weak coupling limits in optics of quantum well excitons: A transition between the strong (coherent) and weak (incoherent) coupling\nlimits of resonant interaction between quantum well (QW) excitons and bulk\nphotons is analyzed and quantified as a function of the incoherent damping rate\ncaused by exciton-phonon and exciton-exciton scattering. For confined QW\npolaritons, a second, anomalous, damping-induced dispersion branch arises and\ndevelops with increasing damping. In this case, the strong-weak coupling\ntransition is attributed to a critical damping rate, when the intersection of\nthe normal and damping-induced dispersion branches occurs. For the radiative\nstates of QW excitons, i.e., for radiative QW polaritons, the transition is\ndescribed as a qualitative change of the photoluminescence spectrum at grazing\nangles along the QW structure. Furthermore, we show that the radiative\ncorrections to the QW exciton states with in-plane wavevector approaching the\nphoton cone are universally scaled by an energy parameter rather than diverge.\nThe strong-weak coupling transition rates are also proportional to the same\nenergy parameter. The numerical evaluations are given for a GaAs single quantum\nwell with realistic parameters.",
        "positive": "Bouncing-ball tunneling in quantum dots: We show that tunneling through quantum dots can be completely dominated by\nstates quantized on stable bouncing-ball orbits. The fingerprints of\nbouncing-ball tunneling are sequences of Coulomb blockade peaks with strongly\ncorrelated peak height and asymmetric peak line shape. Our results are in\nagreement with the striking correlations of peak height and transmission phase\nfound in recent interference experiments with quantum dots."
    },
    {
        "anchor": "Dissipation and noise in adiabatic quantum pumps: We investigate the distribution function, the heat flow and the noise\nproperties of an adiabatic quantum pump for an arbitrary relation of pump\nfrequency $\\omega$ and temperature. To achieve this we start with the\nscattering matrix approach for ac-transport. This approach leads to expressions\nfor the quantities of interest in terms of the side bands of particles exiting\nthe pump. The side bands correspond to particles which have gained or lost a\nmodulation quantum $\\hbar \\omega$. We find that our results for the pump\ncurrent, the heat flow and the noise can all be expressed in terms of a\nparametric emissivity matrix. In particular we find that the current\ncross-correlations of a multiterminal pump are directly related a to a\nnon-diagonal element of the parametric emissivity matrix. The approach allows a\ndescription of the quantum statistical correlation properties (noise) of an\nadiabatic quantum pump.",
        "positive": "Synthetic gauge fields enable high-order topology on Brillouin real\n  projective plane: The topology of the Brillouin zone, foundational in topological physics, is\nalways assumed to be a torus. We theoretically report the construction of\nBrillouin real projective plane ($\\mathrm{RP}^2$) and the appearance of\nquadrupole insulating phase, which are enabled by momentum-space nonsymmorphic\nsymmetries stemming from $\\mathbb{Z}_2$ synthetic gauge fields. We show that\nthe momentum-space nonsymmorphic symmetries quantize bulk polarization and\nWannier-sector polarization nonlocally across different momenta, resulting in\nquantized corner charges and an isotropic binary bulk quadrupole phase diagram,\nwhere the phase transition is triggered by a bulk energy gap closing. Under\nopen boundary conditions, the nontrivial bulk quadrupole phase manifests either\ntrivial or nontrivial edge polarization, resulting from the violation of\nmomentum-space nonsymmorphic symmetries under lattice termination. We present a\nconcrete design for the $\\mathrm{RP}^2$ quadrupole insulator based on acoustic\nresonator arrays and discuss its feasibility in optics, mechanics, and\nelectrical circuits. Our results show that deforming the Brillouin manifold\ncreates opportunities for realizing high-order band topology."
    },
    {
        "anchor": "Dynamic nuclear polarization in InGaAs/GaAs and GaAs/AlGaAs quantum dots\n  under non-resonant ultra-low power optical excitation: We study experimentally the dependence of dynamic nuclear spin polarization\non the power of non-resonant optical excitation in two types of individual\nneutral semiconductor quantum dots: InGaAs/GaAs and GaAs/AlGaAs. We show that\nthe mechanism of nuclear spin pumping via second order recombination of\noptically forbidden (''dark'') exciton states recently reported in InP/GaInP\nquantum dots [Phys. Rev. B 83, 125318 (2011)] is relevant for material systems\nconsidered in this work. In the InGaAs/GaAs dots this nuclear spin polarization\nmechanism is particularly pronounced, resulting in Overhauser shifts up to ~80\nmicro-eV achieved at optical excitation power ~1000 times smaller than the\npower required to saturate ground state excitons. The Overhauser shifts\nobserved at low-power optical pumping in the interface GaAs/AlGaAs dots are\ngenerally found to be smaller (up to ~40 micro-eV). Furthermore in GaAs/AlGaAs\nwe observe dot-to-dot variation and even sign reversal of the Overhauser shift\nwhich is attributed to dark-bright exciton mixing originating from\nelectron-hole exchange interaction in dots with reduced symmetry. Nuclear spin\npolarization degrees reported in this work under ultra-low power optical\npumping are comparable to those achieved by techniques such as resonant optical\npumping or above-gap pumping with high power circularly polarized light.\nDynamic nuclear polarization via second-order recombination of ''dark''\nexcitons may become a useful tool in single quantum dot applications, where\nmanipulation of the nuclear spin environment or electron spin is required.",
        "positive": "Graphene Nanoribbon Field-Effect Transistors on Wafer-Scale Epitaxial\n  Graphene on SiC substrates: We report the realization of top-gated graphene nanoribbon field effect\ntransistors (GNRFETs) of ~10 nm width on large-area epitaxial graphene\nexhibiting the opening of a band gap of ~0.14 eV. Contrary to prior\nobservations of disordered transport and severe edge-roughness effects of GNRs,\nthe experimental results presented here clearly show that the transport\nmechanism in carefully fabricated GNRFETs is conventional band-transport at\nroom temperature, and inter-band tunneling at low temperature. The entire space\nof temperature, size, and geometry dependent transport properties and\nelectrostatics of the GNRFETs are explained by a conventional thermionic\nemission and tunneling current model. Our combined experimental and modeling\nwork proves that carefully fabricated narrow GNRs behave as conventional\nsemiconductors, and remain potential candidates for electronic switching\ndevices."
    },
    {
        "anchor": "Magnons and skyrmions in fractional Hall ferromagnets: Recent experiments have established a qualitative difference between the\nmagnetization temperature-dependences $M(T)$ of quantum Hall ferromagnets at\ninteger and fractional filling factors. We explain this difference in terms of\nthe relative energies of collective magnon and particle-hole excitations in the\ntwo cases. Analytic calculations for hard-core model systems are used to\ndemonstrate that, in the fractional case, interactions suppress the\nmagnetization at finite temperatures and that particle-hole excitations rather\nthan long-wavelength magnons control $M(T)$ at low $T$.",
        "positive": "Coexistence of extended flat band and Kekul\u00e9 order in Li-intercalated\n  graphene: Doping graphene near the 1/4 filling to shift the extended flat band and van\nHove singularity below E$_F$ has been highly desirable. Here we report the\nexperimental observation of an extended flat band below E$_F$ in\nLi-intercalated graphene. Strong electron-phonon interaction is clearly\nidentified by notable kinks in the band dispersion. Moreover, the evolution of\nthe band structure upon Li intercalation shows that the extended flat band and\nthe Kekul\\'e order emerge simultaneously. Our work provides opportunities for\ninvestigating flat band related instabilities and its interplay with the\nKekul\\'e order"
    },
    {
        "anchor": "Discrete-charge Quantum Circuits and Electrical Resistance: From the theory of quantum $LC$ circuits with discrete charge, and {\\em\nsemiclassical} considerations, we obtain approximate energy eigenvalues,\ndepending on the parameter $q_e^2/h$. Next, we include electrical resistance\nfor the quantum $RLC$ circuit, obtaining a relation that strongly reminds us of\nthe Landauer formula.",
        "positive": "States near Dirac points of rectangular graphene dot in a magnetic field: In neutral graphene dots the Fermi level coincides with the Dirac points. We\nhave investigated in the presence of a magnetic field several unusual\nproperties of single electron states near the Fermi level of such a\nrectangular-shaped graphene dot with two zigzag and two armchair edges. We find\nthat a quasi-degenerate level forms near zero energy and the number of states\nin this level can be tuned by the magnetic field. The wavefunctions of states\nin this level are all peaked on the zigzag edges with or without some weight\ninside the dot. Some of these states are magnetic field-independent surface\nstates while the others are field-dependent. We have found a scaling result\nfrom which the number of magnetic field-dependent states of large dots can be\ninferred from those of smaller dots."
    },
    {
        "anchor": "Stability of in-plane and out-of-plane chiral skyrmions in epitaxial\n  MnSi(111)/Si(111) thin films: surface twists versus easy-plane anisotropy: The revisited theoretical phase diagrams for thin films of cubic helimagnets\nwith the easy-plane anisotropy are shown to have different topology as\npreviously reported [Phys. Rev. B 85, 094429 (2012)]. For both in-plane and\nout-of-plane directions of an applied magnetic field, the phase diagrams\nexhibit extensive areas of stable skyrmions, which overlap for a wide range of\nanisotropy parameters. Although the existence of the out-of-plane skyrmions was\ncontradicted within the previous theoretical models, we prove that additional\nsurface twists lead to their stability, while the moderate easy-plane\nanisotropy increases the stability range of in-plane skyrmions. Moreover, the\ninterplay between the anisotropy and the surface twists gives rise to a stable\nspiral state canted with respect to the surfaces. Being absent in bulk\nhelimagnets, this oblique spiral occupies vast areas at the phase diagrams in\nthin-film nanosystems and serves as a connecting-link between cones and\nhelicoids. Our theory gives clear directions for renewed experimental studies\nof in-plane and out-of-plane skyrmions in epitaxial MnSi(111)/Si(111) thin\nfilms.",
        "positive": "Topological Phases in Graphene Nanoribbons: Junction States, Spin\n  Centers and Quantum Spin Chains: Knowledge of the topology of the electronic ground state of materials has led\nto deep insights to novel phenomena such as the integer quantum Hall effect and\nfermion-number fractionalization, as well as other properties of matter.\nJoining two insulators of different topological classes produces fascinating\nboundary states in the band gap. Another exciting recent development is the\nbottom-up synthesis (from molecular precursors) of graphene nanoribbons (GNRs)\nwith atomic precision control of their edge and width. Here we connect these\ntwo fields, and show for the first time that semiconducting GNRs of different\nwidth, edge, and end termination belong to different topological classes. The\ntopology of GNRs is protected by spatial symmetries and dictated by the\nterminating unit cell. We have derived explicit formula for their topological\ninvariants, and show that localized junction states developed between two GNRs\nof distinct topology may be tuned by lateral junction geometry. The topology of\na GNR can be further modified by dopants, such as a periodic array of boron\natoms. In a superlattice consisted of segments of doped and pristine GNRs, the\njunction states are stable spin centers, forming a Heisenberg antiferromagnetic\nspin 1/2 chain with tunable exchange interaction. The discoveries here are not\nonly of scientific interest for studies of quasi one-dimensional systems, but\nalso open a new path for design principles of future GNR-based devices through\ntheir topological characters."
    },
    {
        "anchor": "Generation of coherent acoustic phonons in piezoelectric semiconductor\n  heterostructures: We review some experimental and theoretical aspects of coherent acoustic\nphonon generation in piezoelectric semiconductor multiple quantum wells. In\norder to model more advanced and complicated nano-acoustic devices, a\nmacroscopic continuum theory for the generation and propagation of coherent\nacoustic phonons in piezoelectric semiconductor heterostructures is presented.\nThe macroscopic approach is applicable in the coherent regime, and can be\neasily utilized to study coherent acoustic devices based on piezoelectric\nsemiconductor heterosutructures. For each phonon mode, the corresponding\ncoherent acoustic field obeys a loaded string equation. The driven force has\ncontributions from the piezoelectric and deformation potential couplings. We\napplied the theory to model the generation of coherent longitudinal acoustic\nphonons in (0001)-oriented InGaN/GaN multiple quantum wells. The numerical\nresults are in good agreement with the experimental ones. By using the\nmacroscopic theory, we also investigated the crystal-orientation effects on the\ngeneration of coherent acoustic phonons in wurtzite multiple quantum wells. It\nwas found that coherent transverse acoustic phonons dominate the generation for\ncertain orientation angles.",
        "positive": "Low density ferromagnetism in biased bilayer graphene: We compute the phase diagram of a biased graphene bilayer. The existence of a\nferromagnetic phase is discussed with respect both to carrier density and\ntemperature. We find that the ferromagnetic transition is first order, lowering\nthe value of $U$ relatively to the usual Stoner criterion. We show that in the\nferromagnetic phase the two planes have unequal magnetization and that the\nelectronic density is hole like in one plane and electron like in the other."
    },
    {
        "anchor": "Tunneling Hamiltonian description of the atomic-scale 0-pi transition in\n  superconductor/ferromagnetic-insulator junctions: We show a perturbation theory of the Josephson transport through\nferromagnetic insulators (FIs). Recently we have found that the appearance of\nthe atomic scale 0-pi transition in such junctions based on numerical\ncalculations. In order to explore the mechanism of this anomalous transition,\nwe have analytically calculated the Josephson current using the tunneling\nHamiltonian theory and found that the spin dependent pi-phase shift in the FI\nbarrier gives the atomic scale 0-pi transition.",
        "positive": "Electronic properties of the MoS2-WS2 heterojunction: We study the electronic structure of a heterojunction made of two monolayers\nof MoS2 and WS2. Our first-principles density functional calculations show\nthat, unlike in the homogeneous bilayers, the heterojunction has an optically\nactive band-gap, smaller than the ones of MoS2 and WS2 single layers. We find\nthat that the optically active states of the maximum valence and minimum\nconduction bands are localized on opposite monolayers, and thus the lowest\nenergy electron-holes pairs are spatially separated. Our findings portrait the\nMoS2-WS2 bilayer as a prototypical example for band-gap engineering of\natomically thin two-dimensional semiconducting heterostructures."
    },
    {
        "anchor": "Current-induced non-adiabatic spin torques and domain wall motion with\n  spin relaxation in a ferromagnetic metallic wire: Within the s-d model description, we derive the current-driven spin torque in\na ferromagnet, taking explicitly into account a spin-relaxing Caldeira-Leggett\nbath coupling to the s-electrons. We derive Bloch-Redfield equations of motion\nfor the s-electron spin dynamics, and formulate a systematic gradient expansion\nto obtain non-adiabatic (higher-order) corrections to the well-known adiabatic\n(first-order) spin torque. We provide simple analytical expressions for the\nsecond-order spin torque. The theory is applied to current-driven domain wall\nmotion. Second-order contributions imply a deformation of a transverse\ntail-to-tail domain wall. The wall center still moves with a constant velocity\nthat now depends on the spin-polarized current in a non-trivial manner.",
        "positive": "On mesoscopic forces and quantized conductance in model metallic\n  nanowires: Energetics and conductance in jellium modelled nanowires are investigated\nusing the local-density-functional-based shell correction method. In analogy\nwith studies of other finite-size fermion systems, e.g., simple-metal clusters\nor He-3 clusters, we find that the energetics of the wire as a function of its\nradius (transverse reduced dimension) leads to formation of self-selecting\nmagic wire configurations (MWC's, i.e., discrete sequence of wire radii with\nenhanced stability), originating from quantization of the electronic spectrum,\nnamely formation of subbands which are the analogs of electronic shells in\nclusters. These variations in the energy result in oscillations in the force\nrequired to affect a transition from one MWC of the nanowire to another, and\nare correlated directly with step-wise variations of the quantized conductance\nof the nanowire in units of 2*e^2/h."
    },
    {
        "anchor": "Attraction-repulsion transition in the interaction of adatoms and\n  vacancies in graphene: The interaction of two resonant impurities in graphene has been predicted to\nhave a long-range character with weaker repulsion when the two adatoms reside\non the same sublattice and stronger attraction when they are on different\nsublattices. We reveal that this attraction results from a single energy level.\nThis opens up a possibility of controlling the sign of the impurity interaction\nvia the adjustment of the chemical potential. For many randomly distributed\nimpurities (adatoms or vacancies) this may offer a way to achieve a controlled\ntransition from aggregation to dispersion.",
        "positive": "Many-body dynamical localisation of coupled quantum kicked rotors: The quantum motion of $N$ coupled kicked rotors is mapped to an interacting\n$N$-particle Anderson-Aubry-Andr$\\'e$ tight-binding problem supporting\nmany-body localised (MBL) phases. Interactions in configuration space are known\nto be insufficient for destroying Anderson localisation in a system in the MBL\nphase. The mapping we establish here predicts that a similar effect takes place\nin momentum space and determines the quantum dynamics of the coupled kicked\nrotors. Due to the boundedness of the Floquet quasi-energy spectrum there\nexists limitations on the interacting lattice models that can be mapped to\nquantum kicked rotors; in particular, no extensive observable can be mapped in\nthe thermodynamic limit."
    },
    {
        "anchor": "Phonon and magnon jets above the critical current in nanowires with\n  planar domain walls: We show through non-equilibrium non-adiabatic electron-spin-lattice\nsimulations that above a critical current in magnetic atomic wires with a\nnarrow domain wall (DW), a couple of atomic spaces in width, the electron flow\ntriggers violent stimulated emission of phonons and magnons with an almost\ncomplete conversion of the incident electron momentum flux into a phonon and\nmagnon flux. Just below the critical levels of the current flow, the DW\nachieves maximal velocity of about $3\\times 10^{4}$ m/s, entering a strongly\nnon-adiabatic regime of DW propagation, followed by a breakdown at higher\nbiases. Above this threshold a further increase of the current with the applied\nbias is impossible -- the electronic current suffers a heavy suppression and\nthe DW stops. This poses a fundamental limit to the current densities\nattainable in atomic wires. At the same time it opens up an exciting way of\ngenerating the alternative quasi-particle currents, described above, once the\nrequisite electronic-structure properties are met.",
        "positive": "Antibunching correlations in a strongly coupled exciton - photonic\n  crystal cavity system: Role of off-resonant coupling to multiple excitons: We employ a master equation approach to study the second-order quantum\nautocorrelation functions for up to two independent quantum dot excitons,\ncoupled to an off-resonant cavity in a photonic crystal - single quantum dot\nsystem. For a single coupled off-resonant exciton, we observe novel oscillatory\nbehaviour in the early-time dynamics of the cavity autocorrelation function,\nwhich leads to decreased antibunching relative to the exciton mode. With a\nsecond coupled exciton in the system, we find that the magnitude and the\nlifetime of these oscillations greatly increases, since the cavity is then able\nto exchange photons with multiple excitonic resonances. We unambiguously show\nthat this spoils the antibunching characteristics of the cavity quasi-mode,\nwhile the autocorrelation of the first exciton is unaffected. We also examine\nthe effects of detector time resolution and make a direct connection to a\nseries of recent experiments."
    },
    {
        "anchor": "Plasmonic heating in Au nanowires at low Temperatures: The role of\n  thermal boundary resistance: Inelastic electron tunneling and surface-enhanced optical spectroscopies at\nthe molecular scale require cryogenic local temperatures even under\nillumination - conditions that are challenging to achieve with plasmonically\nresonant metallic nanostructures. We report a detailed study of the laser\nheating of plasmonically active nanowires at substrate temperatures from 5 to\n60 K. The increase of the local temperature of the nanowire is quantified by a\nbolometric approach and could be as large as 100 K for a substrate temperature\nof 5 K and typical values of laser intensity. We also demonstrate that a $\\sim\n3\\times$ reduction of the local temperature increase is possible by switching\nto a sapphire or quartz substrate. Finite element modeling of the heat\ndissipation reveals that the local temperature increase of the nanowire at\ntemperatures below $\\sim$50 K is determined largely by the thermal boundary\nresistance of the metal-substrate interface. The model reproduces the striking\nexperimental trend that in this regime the temperature of the nanowire varies\nnonlinearly with the incident optical power. The thermal boundary resistance is\ndemonstrated to be a major constraint on reaching low temperatures necessary to\nperform simultaneous inelastic electron tunneling and surface enhanced Raman\nspectroscopies.",
        "positive": "Type-II quadrupole topological insulators: Modern theory of electric polarization is formulated by the Berry phase,\nwhich, when quantized, leads to topological phases of matter. Such a\nformulation has recently been extended to higher electric multipole moments,\nthrough the discovery of the so-called quadupole topological insulator. It has\nbeen established by a classical electromagnetic theory that in a\ntwo-dimensional material the quantized properties for the quadupole topological\ninsulator should satisfy a basic relation. Here we discover a new type of\nquadrupole topological insulator (dubbed type-II) that violates this relation\ndue to the breakdown of the correspondence that a Wannier band and an edge\nenergy spectrum close their gaps simultaneously. We find that, similar to the\npreviously discovered (referred to as type-I) quadrupole topological insulator,\nthe type-II hosts topologically protected corner states carrying fractional\ncorner charges. However, the edge polarizations only occur at a pair of\nboundaries in the type-II insulating phase, leading to the violation of the\nclassical constraint. We demonstrate that such new topological phenomena can\nappear from quench dynamics in non-equilibrium systems, which can be\nexperimentally observed in ultracold atomic gases. We also propose an\nexperimental scheme with electric circuits to realize such a new topological\nphase of matter. The existence of the new topological insulating phase means\nthat new multipole topological insulators with distinct properties can exist in\nbroader contexts beyond classical constraints."
    },
    {
        "anchor": "Some open questions in TDDFT: Clues from Lattice Models and\n  Kadanoff-Baym Dynamics: Two aspects of TDDFT, the linear response approach and the adiabatic local\ndensity approximation, are examined from the perspective of lattice models. To\nthis end, we review the DFT formulations on the lattice and give a concise\npresentation of the time-dependent Kadanoff-Baym equations, used to asses the\nlimitations of the adiabatic approximation in TDDFT. We present results for the\ndensity response function of the 3D homogeneous Hubbard model, and point out a\ndrawback of the linear response scheme based on the linearized Sham-Schl\\\"uter\nequation. We then suggest a prescription on how to amend it. Finally, we\nanalyze the time evolution of the density in a small cubic cluster, and compare\nexact, adiabatic-TDDFT and Kadanoff-Baym-Equations densities. Our results show\nthat non-perturbative (in the interaction) adiabatic potentials can perform\nquite well for slow perturbations but that, for faster external fields, memory\neffects, as already present in simple many-body approximations, are clearly\nrequired.",
        "positive": "Non-local response in the disordered Majorana chain: The prospects for realizing a topological quantum computer have brightened\nsince the apparent detection of Majorana fermions at the ends of semiconducting\nnanowires. These Majorana zero-modes persist in the presence of the strong\ndisorder that may be present in such systems, protected by the mobility gap of\nlocalized systems. Recent proposals to manipulate quantum information in a\nMajorana chain involve adiabatically adjusting gate voltages in one-dimensional\nnanowire networks. However, as we show, in the adiabatic limit, a disordered\nsystem with multiple zero-mode Majorana fermions will undergo a non-local\nresponse to a local perturbation via a multi-level Landau-Zener transition.\nThis will disperse the quantum information stored in the target zero-modes\namongst other zero-modes that are present in the system, complicating the\nrealization of controlled gates. There is however a solution that may work in\npractice: we show that there is an optimum window of intermediate time-scales\nduring which the quantum information is approximately preserved under\nmanipulation."
    },
    {
        "anchor": "Nonanalytic enhancement of the charge transfer from adatom to\n  one-dimensional semiconductor superlattice and optical absorption spectrum: The charge transfer from an adatom to a semiconductor substrate of\none-dimensional quantum dot array is evaluated theoretically. Due to the Van\nHove singularity in the density of electron states at the band edges, the\ncharge transfer decay rate is enhanced nonanalytically in terms of the coupling\nconstant $g$ as $g^{4/3}$. The optical absorption spectrum for the ionization\nof a core level electron of the adatom to the conduction band is also\ncalculated. The reversible non-Markovian process and irreversible Markovian\nprocess in the time evolution of the adatom localized state manifest themselves\nin the absorption spectrum through the branch point and pole contributions,\nrespectively.",
        "positive": "Theoretical realization of two-dimensional M3(C6X6)2(M= Co, Cr, Cu, Fe,\n  Mn, Ni, Pd, Rh and X= O, S, Se) metal-organic frameworks: Most recently, Cu-hexahydroxybenzene MOF was for the time experimentally\nrealized, through a kinetically controlled approach. Cu-HHB belongs to the\nfamily of conductive MOFs with a chemical formula of M3(C6X6)2(X=NH, O, S).\nMotivated by the recent experimental advance in the fabrication of Cu-HHB, we\nconducted extensive first-principles simulations to explore the thermal\nstability, mechanical properties and electronic characteristics of M3(C6X6)2(M=\nCo, Cr, Cu, Fe, Mn, Ni, Pd, Rh and X= O, S, Se) monolayers. First-principles\nresults confirm that all considered 2D porous lattices are thermally stable at\nhigh temperatures over 1500 K. It was moreover found that these novel 2D\nstructures can exhibit linear elasticity with considerable tensile strengths,\nrevealing their suitability for practical applications in nanodevices.Depending\non the metal and chalcogen atoms in M3(C6X6)2 monolayers, they can yield\nvarious electronic and magnetic properties, such as; magnetic semiconducting,\nperfect half metallic, magnetic and nonmagnetic metallic behaviours. This work\nhighlights the outstanding physics of M3(C6X6)2 2D porous lattices and will\nhopefully help to expand this conductive MOF family, as promising candidates to\ndesign advanced energy storage/conversion, electronics and spintronics systems."
    },
    {
        "anchor": "Nonresonant amplification of coherent spin waves through voltage-induced\n  interface magnetoelectric effect and spin-transfer torque: We present new mechanism for manipulation of the spin-wave amplitude through\nthe use of the dynamic charge-mediated magnetoelectric effect in ultrathin\nmultilayers composed of dielectric thin-film capacitors separated by a\nferromagnetic bilayer. Propagating spin waves can be amplified and attenuated\nwith rising and decreasing slopes of the oscillating voltage, respectively,\nlocally applied to the sample. The way the spin accumulation is generated makes\nthe interaction of the spin-transfer torque with the magnetization dynamics\nmode-selective and restricted to some range of spin-wave frequencies, which is\nin contrary to known types of the spin-transfer torque effects. The interfacial\nnature of spin-dependent screening allows to reduce the thickness of the fixed\nmagnetization layer to a few nanometers, thus the proposed effect significantly\ncontributes toward realization of the magnonic devices and also miniaturization\nof the spintronic devices.",
        "positive": "Artificial graphene as a tunable Dirac material: Artificial honeycomb lattices offer a tunable platform to study massless\nDirac quasiparticles and their topological and correlated phases. Here we\nreview recent progress in the design and fabrication of such synthetic\nstructures focusing on nanopatterning of two-dimensional electron gases in\nsemiconductors, molecule-by-molecule assembly by scanning probe methods, and\noptical trapping of ultracold atoms in crystals of light. We also discuss\nphotonic crystals with Dirac cone dispersion and topologically protected edge\nstates. We emphasize how the interplay between single-particle band structure\nengineering and cooperative effects leads to spectacular manifestations in\ntunneling and optical spectroscopies."
    },
    {
        "anchor": "Thermal Relaxation Rates of Magnetic Nanoparticles in the Presence of\n  Magnetic Fields and Spin-Transfer Effects: We have measured the relaxation time of a thermally unstable ferromagnetic\nnanoparticle incorporated into a magnetic tunnel junction (MTJ) as a function\nof applied magnetic field, voltage V (-0.38 V < V < +0.26 V), and temperatures\n(283 K< T< 363 K) . By analyzing the results within the framework of a modified\nN\\'eel-Brown formalism we determine the effective attempt time of the\nnanoparticle and also the bias dependences of the in-plane and out-of-plane\nspin torques. There is a significant linear modification of the effective\ntemperature with voltage due to the in-plane torque and a significant\ncontribution of a \"field like\" torque that is quadratic with voltage. The\nmethods presented here do not require complicated models for device heating or\ncalibration procedures, but instead directly measure how temperature, field,\nand voltage influence the energy landscape and thermal fluctuations of a\ntwo-state system. These results should have significant implications for\ndesigns of future nanometer-scale magnetic random access memory elements and\nprovide a straightforward methodology to determine these parameters in other\nMTJ device structures.",
        "positive": "Leakage and sweet spots in triple-quantum-dot spin qubits: A\n  molecular-orbital study: A triple-quantum-dot system can be operated as either an exchange-only qubit\nor a resonant-exchange qubit. While it is generally believed that the decisive\nadvantage of the resonant-exchange qubit is the suppression of charge noise\nbecause it is operated at a sweet spot, we show that the leakage is also an\nimportant factor. Through molecular-orbital-theoretic calculations, we show\nthat when the system is operated in the exchange-only scheme, the leakage to\nstates with double electron occupancy in quantum dots is severe when rotations\naround the axis 120$^\\circ$ from $\\hat{z}$ is performed. While this leakage can\nbe reduced by either shrinking the dots or separating them further, the\nexchange interactions are also suppressed at the same time, making the gate\noperations unfavorably slow. When the system is operated as a resonant-exchange\nqubit, the leakage is 3-5 orders of magnitude smaller. We have also calculated\nthe optimal detuning point which minimizes the leakage for the\nresonant-exchange qubit, and have found that although it does not coincide with\nthe double-sweet-spot for the charge noise, they are rather close. Our results\nsuggest that the resonant-exchange qubit has another advantage that leakage can\nbe greatly suppressed compared to the exchange-only qubit, and operating at the\ndouble-sweet-spot point should be optimal both for reducing charge noise and\nsuppressing leakage."
    },
    {
        "anchor": "Tunable surface plasmons in Weyl semimetals TaAs and NbAs: By means of high-resolution electron energy loss spectroscopy, we investigate\nthe low-energy excitation spectrum of transition-metal monopnictides hosting\nWeyl fermions. We observe gapped plasmonic modes in (001)-oriented surfaces of\nsingle crystals of NbAs and TaAs at 66 and 68 meV, respectively. Our findings\nare consistent with theory and we estimate an effective Coulomb interaction\nstrength $\\alpha_{\\rm eff}\\approx0.41$ for both samples. We also demonstrate\nthat the modification of the surface of transition-metal monopnictides by the\nadsorption of chemical species (in our case, oxygen and hydrocarbon fragments)\nchanges the frequency of the plasmonic excitations, with a subsequent\nmodification of the effective interaction strength in the 0.30-0.48 range. The\nremarkable dependence of plasmonic features on the presence of adsorbates paves\nthe way for plasmonic sensors based on Weyl semimetals operating in the\nmid-infrared.",
        "positive": "Edge-dependent reflection and inherited fine structure of higher-order\n  plasmons in graphene nanoribbons: We investigate higher-order plasmons in graphene nanoribbons, and present how\nelectronic edge states and wavefunction fine structure influence the graphene\nplasmons. Based on nearest-neighbor tight-binding calculations, we find that a\nstanding-wave model based on nonlocal bulk plasmon dispersion is surprisingly\naccurate for armchair ribbons of widths even down to a few nanometers, and we\ndetermine the corresponding phase shift upon edge reflection and an effective\nribbon width. Wider zigzag ribbons exhibit a similar phase shift, whereas the\nstanding-wave model describes few-nanometer zigzag ribbons less satisfactorily,\nto a large extent because of their edge states. We directly confirm that also\nthe larger broadening of plasmons for zigzag ribbons is due to their edge\nstates. Furthermore, we report a prominent fine structure in the induced\ncharges of the ribbon plasmons, which for armchair ribbons follows the\nelectronic wavefunction oscillations induced by inter-valley coupling.\nInterestingly, the wavefunction fine structure is also found in our analogous\ndensity-functional theory calculations, and both these and tight-binding\nnumerical calculations are explained quite well with analytical Dirac theory\nfor graphene ribbons."
    },
    {
        "anchor": "Lifetime of metastable states in resonant tunneling structures: We investigate the transport of electrons through a double-barrier\nresonant-tunneling structure in the regime where the current-voltage\ncharacteristics exhibit bistability. In this regime one of the states is\nmetastable, and the system eventually switches from it to the stable state. We\nshow that the mean switching time grows exponentially as the voltage across the\ndevice is tuned from the its boundary value into the bistable region. In\nsamples of small area we find that the logarithm of the lifetime is\nproportional to the voltage (measured from its boundary value) to the 3/2\npower, while in larger samples the logarithm of the lifetime is linearly\nproportional to the voltage.",
        "positive": "Cross-plane heat conduction in thin solid films: Cross-plane heat transport in thin films with thickness comparable to the\nphonon mean free paths is of both fundamental and practical interest. However,\nphysical insight is difficult to obtain for the cross-plane geometry due to the\nchallenge of solving the Boltzmann equation in a finite domain. Here, we\npresent a semi-analytical series expansion method to solve the transient,\nfrequency-dependent Boltzmann transport equation that is valid from the\ndiffusive to ballistic transport regimes and rigorously includes\nfrequency-dependence of phonon properties. Further, our method is more than\nthree orders of magnitude faster than prior numerical methods and provides a\nsimple analytical expression for the thermal conductivity as a function of film\nthickness. Our result enables a more accurate understanding of heat conduction\nin thin films."
    },
    {
        "anchor": "Effective Quantum Theories for Transport in Inhomogeneous Systems with\n  Non-trivial Band Structure: Starting from a general $N$-band Hamiltonian with weak spatial and temporal\nvariations, we derive a low energy effective theory for transport within one or\nseveral overlapping bands. To this end, we use the Wigner representation that\nallows us to systematically construct the unitary transformation that brings\nthe Hamiltonian into band-diagonal form. We address the issue of gauge\ninvariance and discuss the necessity of using kinetic variables in order to\nobtain a low energy effective description that is consistent with the original\ntheory. Essentially, our analysis is a semiclassical one and quantum\ncorrections appear as Berry curvatures in addition to quantities that are\nrelated to the appearance of persistent currents. We develop a transport\nframework which is manifestly gauge invariant and it is based on a quantum\nBoltzman formulation along with suitable definitions of current density\noperators such that Liouville's theorem is satisfied. Finally, we incorporate\nthe effects of an external electromagnetic field into our theory.",
        "positive": "High sensitivity electrochemical DNA sensors for detection of somatic\n  mutations in FFPE samples: We offer new high-performance label-free electrochemical impedimetric DNA\nsensors of non-faradaic type. The DNA sensors based on a platform of\ncrystalline carbon nanotube (CNT) arrays are fabricated by the\nLangmuir--Blodgett (LB) deposition technique. The CNT arrays are suspended on a\nnanoporous anodic alumina (aluminium oxide, AOA) support. Single-stranded (ss)\n19- and 20-base oligonucleotides and double-stranded (ds) nucleotide sequences\nwere used as probes for chosen molecular target -- human KRAS (Kirsten Rat\nSarcoma viral oncogene homolog) gene. Genomic deoxyribonucleic acids (DNAs)\nwere isolated from placenta of healthy donors and FFPE (formalin-fixed,\nparaffinembedded) samples of tumor tissue. Raman spectral analysis and\nelectrochemical dielectric spectroscopy were used to sequence the target DNAs.\nThe optical and electrochemical detection (variants of DNA sequencing) were\nbased on a screening effect that grows after the DNA homoduplex formation. We\ndemonstrated that such technologies are very sensitive and allow to detect\nattomolar DNA concentrations and less. As result, the KRAS exon 2, codon 12,\nc.35G$>$A mutation was successfully discriminated in human genomic DNA isolated\nfrom FFPE colorectal cancer tumor tissue samples."
    },
    {
        "anchor": "Novel self-epitaxy for inducing superconductivity in the topological\n  insulator (Bi1-xSbx)2Te3: Using the superconducting proximity effect for engineering a topological\nsuperconducting state in a topological insulator (TI) is a promising route to\nrealize Majorana fermions. However, epitaxial growth of a superconductor on the\nTI surface to achieve a good proximity effect has been a challenge. We\ndiscovered that simply depositing Pd on thin films of the TI material\n(Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ leads to an epitaxial self-formation of PdTe$_2$\nsuperconductor having the superconducting transition temperature of ~1 K. This\nself-formed superconductor proximitizes the TI, which is confirmed by the\nappearance of a supercurrent in Josephson-junction devices made on\n(Bi$_{1-x}$Sb$_x$)$_2$Te$_3$. This self-epitaxy phenomenon can be conveniently\nused for fabricating TI-based superconducting nanodevices to address the\nsuperconducting proximity effect in TIs.",
        "positive": "Detection and measurement of spin-dependent dynamics in random telegraph\n  signals: A quantum point contact was used to observe single-electron fluctuations of a\nquantum dot in a GaAs heterostructure. The resulting random telegraph signals\n(RTS) contain statistical information about the electron spin state if the\ntunneling dynamics are spin-dependent. We develop a statistical method to\nextract information about spin-dependent dynamics from RTS and use it to\ndemonstrate that these dynamics can be studied in the thermal energy regime.\nThe tunneling rates of each spin state are independently measured in a finite\nexternal magnetic field. We confirm previous findings of a decrease in overall\ntunneling rates for the spin excited state compared to the ground state as an\nexternal magnetic field is increased."
    },
    {
        "anchor": "Spin polarization of electron current on the quantum well with\n  exchange-splitted levels: The backscattering process of injected electrons on exchange-splitted levels\nof quantum well (QW) in ferromagnetic metal / insulator / semiconductor\nheterostructure is studied. It is found that, if one of the exchange-splitted\nlevels lies in the top region of the QW and the energy of injected electrons is\nclose to the energy of localized electron on this level, the backward\nscattering becomes dependent on spins of injected electrons. Accumulation of\nbackscattered electrons in the QW leads to considerable reduction of the\ncurrent depended on its spin orientation. The spin polarization increases with\ngrowth of the applied electric field and the storage time of electrons in the\nQW. High values of the spin polarization can be achieved at room temperature.\nIn this way, the QW with exchange-splitted levels in ferromagnetic metal /\ninsulator / semiconductor heterostructure can be used as effective spin filter.",
        "positive": "Weak-field Hall effect and static polarizability of Bloch electrons: A theory of the weak field Hall effect of Bloch electrons based on the\nanalysis of the forces acting on electrons is presented. It is argued that the\nelectric current is composed of two contributions, that driven by the electric\nfield along current flow and the non-dissipative contribution originated in\ndemagnetization currents. The Hall resistance as a function of the electron\nconcentration for the tight-binding model of a crystal with square lattice and\nbody-centered cubic lattice is described in detail. For comparison the effect\nof strong magnetic fields is also discussed."
    },
    {
        "anchor": "Interaction effects in non-equilibrium transport properties of a\n  four-terminal topological corner junction: We study the transport properties of a four-terminal corner junction made by\netching a two- dimensional topological insulator to form a quantum point\ncontact (QPC). The QPC geometry enables inter-boundary tunneling processes\nallowing for the coupling among states with different helicity, while the tight\nconfinement in the QPC region activates charging effects leading to the Coulomb\nblockade physics. Peculiar signatures of these effects are theoretically\ninvestigated using a scattering field theory modified to take into account the\nelectron-electron interaction within a self- consistent mean-field approach.\nThe current-voltage characteristics and the current fluctuations (noise) are\nderived beyond the linear response regime. Universal aspects of the thermal\nnoise of the corner junction made of helical matter are also discussed.",
        "positive": "Exact solution for many-body Hamiltonian of interacting particles with\n  linear spectrum: The exact solution of the Schr\\\"odinger equation for the one-dimensional\nsystem of interacting particles with the linear dispersion law in an arbitrary\nexternal field is found. The solution is reduced to two groups of particles\nmoving with constant velocities in the opposite directions with a fixed\ndistance between the particles in each group. The problem is applied to the\nedge states of the 2D topological insulator."
    },
    {
        "anchor": "Cotunneling through a quantum dot coupled to ferromagnetic leads with\n  noncollinear magnetizations: Spin-dependent electronic transport through a quantum dot has been analyzed\ntheoretically in the cotunneling regime by means of the second-order\nperturbation theory. The system is described by the impurity Anderson\nHamiltonian with arbitrary Coulomb correlation parameter $U$. It is assumed\nthat the dot level is intrinsically spin-split due to an effective molecular\nfield exerted by a magnetic substrate. The dot is coupled to two ferromagnetic\nleads whose magnetic moments are noncollinear. The angular dependence of\nelectric current, tunnel magnetoresistance, and differential conductance are\npresented and discussed. The evolution of a cotunneling gap with the angle\nbetween magnetic moments and with the splitting of the dot level is also\ndemonstrated.",
        "positive": "Electron and hole spin dynamics and decoherence in quantum dots: In this article we review our work on the dynamics and decoherence of\nelectron and hole spins in single and double quantum dots. The first part, on\nelectron spins, focuses on decoherence induced via the hyperfine interaction\nwhile the second part covers decoherence and relaxation of heavy-hole spins due\nto spin-orbit interaction as well as the manipulation of heavy-hole spin using\nelectric dipole spin resonance."
    },
    {
        "anchor": "Theory of magnetism in the van der Waals magnet CrI3: We study the microscopical origin of anisotropic ferromagnetism in the van\nder Waals magnet CrI3. We conclude that the nearest neighbors exchange is well\ndescribed by the Heisenberg-Kitaev-Gamma (HKGamma) model, and we also found a\nnonzero Dzyaloshinskii-Moriya interaction (DMI) on next nearest neighbors. Both\nKitaev and DMI are known to generate a non-trivial topology of the magnons in\nthe honeycomb lattice and have been used separately to describe the low energy\nregime of this material. We discuss that including one or the other leads to\ndifferent signs of the Chern number. Furthermore, the topological gap at\nK-point seems to be mainly produced by DMI, despite it is one order of\nmagnitude smaller than Kitaev. Finally, we show that by applying an external\nelectric field perpendicular to the crystal plane, it is possible to induce DMI\non nearest neighbors, and this could have consequences in non-collinear spin\ntextures, such as domain walls and skyrmions.",
        "positive": "Mesoscopic transition in the shot noise of diffusive S/N/S junctions: We experimentally investigated the current noise in diffusive\nSuperconductor/Normal metal/Superconductor junctions with lengths between the\nsuperconducting coherence length xi_Delta and the phase coherence length L_Phi\nof the normal metal (xi_Delta < L < L_Phi). We measured the shot noise over a\nlarge range of energy covering both the regimes of coherent and incoherent\nmultiple Andreev reflections. The transition between these two regimes occurs\nat the Thouless energy where a pronounced minimum in the current noise density\nis observed. Above the Thouless energy, in the regime of incoherent multiple\nAndreev reflections, the noise is strongly enhanced compared to a normal\njunction and grows linearly with the bias voltage. Semi-classical theory\ndescribes the experimental results accurately, when taking into account the\nvoltage dependence of the resistance which reflects the proximity effect. Below\nthe Thouless energy, the shot noise diverges with decreasing voltage which may\nindicate the coherent transfer of multiple charges."
    },
    {
        "anchor": "RKKY Interaction in Graphene Calculated Following Ruderman and Kittel: This paper has been withdrawn because it has been by far superseded by the\nAuthor's post arXiv:1108.1306v6, which was published on 30/08/2011.",
        "positive": "Electronic compressibility of graphene: The case of vanishing electron\n  correlations and the role of chirality: A recent surprising finding that electronic compressibility measured\nexperimentally in monolayer graphene can be described solely in terms of the\nkinetic energy [J. Martin, et al., Nat. Phys. 4, 144 (2008)] is explained\ntheoretically as a direct consequence of the linear energy dispersion and the\nchirality of massless Dirac electrons. For bilayer graphene we show that\ncontributions to the compressibility from the electron correlations are\nrestored. We attribute the difference to the respective momentum dependence of\nthe low energy band structures of the two materials."
    },
    {
        "anchor": "Giant Faraday effect due to Pauli exclusion principle in 3D topological\n  insulators: Experiments using ARPES, which is based on the photoelectric effect, show\nthat the surface states in 3D topological insulators (TI) are helical. Here we\nconsider Weyl interface fermions due to band inversion in narrow-bandgap\nsemiconductors, such as Pb$_{1-x}$Sn$_{x}$Te. The positive and negative energy\nsolutions can be identified by means of opposite helicity in terms of the spin\nhelicity operator in 3D TI as\n$\\hat{h}_{\\textrm{TI}}=\\left(1/\\left|p_{\\bot}\\right|\\right)\\beta\\left(\\boldsymbol{\\sigma}_{\\perp}\\times\\boldsymbol{p}_{\\perp}\\right)\\cdot\\boldsymbol{\\hat{z}}$,\nwhere $\\beta$ is a Dirac matrix and $\\boldsymbol{\\hat{z}}$ points perpendicular\nto the interface. Using the 3D Dirac equation and bandstructure calculations we\nshow that the transitions between positive and negative energy solutions,\ngiving rise to electron-hole pairs, obey strict optical selection rules. In\norder to demonstrate the consequences of these selection rules, we consider the\nFaraday effect due to Pauli exclusion principle in a pump-probe setup using a\n3D TI double interface of a PbTe/Pb$_{0.31}$Sn$_{0.69}$Te/PbTe heterostructure.\nFor that we calculate the optical conductivity tensor of this heterostructure,\nwhich we use to solve Maxwell's equations. The Faraday rotation angle exhibits\noscillations as a function of probe wavelength and thickness of the\nheterostructure. The maxima in the Faraday rotation angle are of the order of\nmillirads.",
        "positive": "Influence of metal contacts and charge inhomogeneity on transport\n  properties of graphene near the neutrality point: There is an increasing amount of literature concerning electronic properties\nof graphene close to the neutrality point. Many experiments continue using the\ntwo-probe geometry or invasive contacts or do not control samples' macroscopic\nhomogeneity. We believe that it is helpful to point out some problems related\nto such measurements. By using experimental examples, we illustrate that the\ncharge inhomogeneity induced by spurious chemical doping or metal contacts can\nlead to large systematic errors in assessing graphene's transport properties\nand, in particular, its minimal conductivity. The problems are most severe in\nthe case of two-probe measurements where the contact resistance is found to\nstrongly vary as a function of gate voltage."
    },
    {
        "anchor": "Interference dislocations in condensate of indirect excitons: Phase singularities in quantum states play a significant role both in the\nstate properties and in the transition between the states. For instance, a\ntransition to two-dimensional superfluid state is governed by pairing of\nvortices and, in turn, unpaired vortices can cause dissipations for particle\nfluxes. Vortices and other phase defects can be revealed by characteristic\nfeatures in interference patterns produced by the quantum system. We present\ndislocation-like phase singularities in interference patterns in a condensate\nof indirect excitons measured by shift-interferometry. We show that the\nobserved dislocations in interference patterns are not associated with\nconventional phase defects: neither with vortices, nor with polarization\nvortices, nor with half-vortices, nor with skyrmions, nor with half-skyrmions.\nWe present the origin of these new phase singularities in condensate\ninterference patterns: the observed interference dislocations originate from\nconverging of the condensate matter waves propagating from different sources.",
        "positive": "Strain and spin orbit coupling effects on electronic and optical\n  properties of 2D CX/graphene (X = S, Se, Te) vdW heterostructure for solar\n  energy harvesting: Vertically stacked two-dimensional (2D) graphene-based van der Waals (vdW)\nheterostructures have emerged as the technological materials for electronic and\noptoelectronic device applications. In this regard, for the first time, we\nsystematically predicted the electronic and optical properties of CX/G (X = S,\nSe and Te; G = graphene) heterostructures under biaxial strain and spin orbit\ncoupling (SOC) by first-principles calculations. Strain is induced by applying\nmechanical stress to the heterostructures, while SOC arises due to the\ninteraction between the electron spin and its orbital motion. The electronic\nproperty calculations reveal that all three heterostructures exhibit indirect\nsemiconducting nature with a narrow bandgap of 0.47-0.62 eV and remain indirect\nunder compressive and tensile strains. Strong band splitting of 78.4 meV has\nbeen observed in the conduction band edge of CTe/G heterostructure in the\npresence of SOC due to the lack of an inversion center attributed to the large\nhole effective mass. Under compressive strain, the p-type of Schottky contact\nof CX/G heterostructures is converted into p-type Ohmic contact because of\nnearly negligible Schottky barrier height. Further, the optical property\nassessment reveals red and blue shifts in the absorption peak of CX/G\nheterostructures with regard to tensile and compressive strains, respectively.\nDespite this, the CTe/G heterostructure achieves a remarkable high {\\eta} of\n24.53% in the strain-free case whereas, it reaches to 28.31% with 4%\ncompressive strain, demonstrating the potential for solar energy conversion\ndevice applications. Our findings suggest that CX/G heterostructures could be\npromising candidates for high-performance optoelectronic devices."
    },
    {
        "anchor": "Cold atoms in double-well optical lattices: Cold atoms, loaded into an optical lattice with double-well sites, are\nconsidered. Pseudospin representation for an effective Hamiltonian is derived.\nThe system in equilibrium displays two phases, ordered and disordered. The\nsecond-order phase transition between the phases can be driven either by\ntemperature or by changing the system parameters. Collective pseudospin\nexcitations have a gap disappearing at the phase-transition point. Dynamics of\natoms is studied, when they are loaded into the lattice in an initially\nnonequilibrium state. It is shown that the temporal evolution of atoms,\ncontrary to their equilibrium thermodynamics, cannot be described in the\nmean-field approximation, since it results in a structurally unstable dynamical\nsystem, but a more accurate description is necessary taking account of\nattenuation effects.",
        "positive": "Valley polarized electronic beam splitting in graphene: We show how the trigonal warping effect in doped graphene can be used to\nproduce fully valley polarized currents. We propose a device that acts both as\na beam splitter and a collimator of these electronic currents. The result is\ndemonstrated trough an optical analogy using two dimensional photonic crystals."
    },
    {
        "anchor": "Kondo screening of a high-spin Nagaoka state in a triangular quantum dot: We study transport through a triangle triple quantum dot connected to two\nnoninteracting leads using the numerical renormalization group (NRG). The\ntriangle has a high-spin ground state of S=1 caused by a Nagaoka\nferromagnetism, when it is isolated and has one extra electron introduced into\na half-filling. The results show that the conduction electrons screen the local\nmoment via two separate stages with different energy scales. The half of the\nS=1 is screened first by one of the channel degrees, and then at very low\ntemperature the remaining half is fully screened to form a Kondo singlet. The\ntransport is determined by two phase shifts for quasi-particles with even and\nodd parities, and then a two-terminal conductance in the series configuration\nis suppressed $g_{\\rm series} \\simeq 0$, while plateau of a four-terminal\nparallel conductance reaches a Unitary limit value $g_{\\rm parallel} \\simeq\n4e^2/h$ of two conducting modes.",
        "positive": "Electric- and magnetic-field dependence of the electronic and optical\n  properties of phosphorene quantum dots: Recently, black phosphorus quantum dots were fabricated experimentally.\nMotivated by these experiments, we theoretically investigate the electronic and\noptical properties of rectangular phosphorene quantum dots (RPQDs) in the\npresence of an in-plane electric field and a perpendicular magnetic field. The\nenergy spectra and wave functions of RPQDs are obtained numerically using the\ntight-binding (TB) approach. We find edge states within the band gap of the\nRPQD which are well separated from the bulk states. In an undoped RPQD and for\nin-plane polarized light, due to the presence of well-defined edge states, we\nfind three types of optical transitions which are between the bulk states,\nbetween the edge and bulk states, and between the edge states. The electric and\nmagnetic fields influence the bulk-to-bulk, edge-to-bulk, and edge-to-edge\ntransitions differently due to the different responses of bulk and edge states\nto these fields."
    },
    {
        "anchor": "Charged spin textures over the Moore-Read quantum Hall state: We study charged spin textures (CST) over the Moore-Read quantum Hall state\nat filling factor 5/2. We develop an algebraic framework and show that the\npairing condition that is inherent in the Moore-Read state naturally leads to a\nclass of charged spin textures, labeled by winding numbers [w_I, w_II]. The\nfundamental CST, with labels [1,0] and electric charge e/4, is identified with\nthe polar core vortex known in the spin-1 BEC literature. The spin texture\ncarried by the fusion product of fundamental CSTs is correlated with the fusion\nchannel of the underlying non-Abelian quasiholes.",
        "positive": "A Theory of Electrodynamic Responses for Bounded Metals: Surface\n  Capacitive Effects: We report a general macroscopic theory for the electrodynamic response of\nsemi-infinite metals (SIMs). The theory includes the hitherto overlooked\ncapacitive effects due to the finite spatial extension of a surface. The basic\nstructure of this theory is independent of the particulars of electron\ndynamics. Analytical expressions have been obtained of the charge\ndensity-density response function, which is naturally parsed into two parts.\nOne of them represents a bulk property while the other a pure surface property.\nWe apply the theory to study the responses according to several electronic\ndynamics models and provide a unified view of their validity and limitations.\nThe models studied include the local dielectric model (DM), the dispersive\nhydrodynamic model (HDM) and specular reflection model (SRM), as well as the\nless common semi-classical model (SCM) based on Boltzmann's transport equation.\nWe show that, in terms of their basic equations, the SRM is an extension of the\nHDM, just as the HDM is an extension of the DM. The SCM improves over the SRM\ncritically through the inclusion of translation symmetry breaking and surface\nroughness effects. We then employ the response function to evaluate the\nso-called dynamical structure factor, which plays an important role in particle\nscattering. As expected, this factor reveals a peak due to the excitation of\nsurface plasma waves (SPWs). Surprisingly, however, the peak is shown to be\nconsiderably sharper in the SCM than in other models, indicating an incipient\ninstability of the system according to this model. We also study the\ndistribution of charges induced by a charged particle grazing over a SIM\nsurface at constant speed. This distribution is shown to contain model-specific\nfeatures that are of immediate experimental interest."
    },
    {
        "anchor": "Quantum anomalous Hall state in a fluorinated 1T-MoSe$_2$ monolayer: The quantum anomalous Hall state with a large band gap and a high Chern\nnumber is significant for practical applications in spintronics. By performing\nfirst-principles calculations, we investigate electronic properties of the\nfully fluorinated 1T-MoSe$_{2}$ monolayer. Without considering the spin-orbit\ncoupling, the band structure demonstrates single-spin semi-metallic properties\nand the trigonal warping around $K_{\\pm}$ valleys. The introduction of the\nspin-orbit coupling opens considerable band gaps of $117.2$ meV around the two\nvalleys, leading to a nontrivial quantum anomalous Hall state with a Chern\nnumber of $|C|=2$, which provides two chiral dissipationless transport channels\nfrom topological edge states and associated quantized anomalous Hall\nconductivity. In addition, an effective model is constructed to describe the\nlow-energy physics of the monolayer. Our findings in the MoSe$_{2}$F$_{2}$\nmonolayer sheds light on large-gap quantum anomalous Hall states in\ntwo-dimensional materials with the chemical functionalization, and provides\nopportunities in designing low-power and noise-tolerant spintronic devices.",
        "positive": "Electrically Tunable Spin Polarization in a Carbon-Nanotube Spin Diode: We have studied the current through a carbon nanotube quantum dot with one\nferromagnetic and one normal-metal lead. For the values of gate voltage at\nwhich the normal lead is resonant with the single available non-degenerate\nenergy level on the dot, we observe a pronounced decrease in the current for\none bias direction. We show that this rectification is spin-dependent, and that\nit stems from the interplay between the spin accumulation and the Coulomb\nblockade on the quantum dot. Our results imply that the current is\nspin-polarized for one direction of the bias, and that the degree of spin\npolarization is fully and precisely tunable using the gate and bias voltages.\nAs the operation of this spin diode does not require high magnetic fields or\noptics, it could be used as a building block for electrically controlled\nspintronic devices."
    },
    {
        "anchor": "Universal field dependence of magnetic resonance near zero frequency: Magnetic resonance is a widely-established phenomenon that probes magnetic\nproperties such as magnetic damping and anisotropy. Even though the typical\nresonance frequency of a magnet ranges from gigahertz to terahertz, experiments\nalso report the resonance near zero frequency in a large class of magnets. Here\nwe revisit this phenomenon by analyzing the symmetry of the system and find\nthat the resonance frequency ($\\omega$) follows a universal power law $\\omega\n\\varpropto |H-H_c|^p$, where $H_c$ is the critical field at which the resonance\nfrequency is zero. When the magnet preserves the rotational symmetry around the\nexternal field ($H$), $p = 1$. Otherwise, $p=1/2$. The magnon excitations are\ngapped above $H_c$, gapless at $H_c$ and gapped again below $H_c$. The zero\nfrequency is often accompanied by a reorientation transition in the\nmagnetization. For the case that $p=1/2$, this transition is described by a\nLandau theory for second-order phase transitions. We further show that the spin\ncurrent driven by thermal gradient and spin-orbit effects can be significantly\nenhanced when the resonance frequency is close to zero, which can be measured\nelectrically by converting the spin current into electric signals. This may\nprovide an experimentally accessible way to characterize the critical field.\nOur findings provide a unified understanding of the magnetization dynamics near\nthe critical field, and may, furthermore, inspire the study of magnon transport\nnear magnetic transitions.",
        "positive": "Inelastic electron tunneling via molecular vibrations in single-molecule\n  transistors: In single-molecule transistors, we observe inelastic cotunneling features\nthat correspond energetically to vibrational excitations of the molecule, as\ndetermined by Raman and infrared spectroscopy. This is a form of inelastic\nelectron tunneling spectroscopy of single molecules, with the transistor\ngeometry allowing in-situ tuning of the electronic states via a gate electrode.\nThe vibrational features shift and change shape as the electronic levels are\ntuned near resonance, indicating significant modification of the vibrational\nstates. When the molecule contains an unpaired electron, we also observe\nvibrational satellite features around the Kondo resonance."
    },
    {
        "anchor": "Coherent spin qubit transport in silicon: A fault-tolerant quantum processor may be configured using stationary qubits\ninteracting only with their nearest neighbours, but at the cost of significant\noverheads in physical qubits per logical qubit. Such overheads could be reduced\nby coherently transporting qubits across the chip, allowing connectivity beyond\nimmediate neighbours. Here we demonstrate high-fidelity coherent transport of\nan electron spin qubit between quantum dots in isotopically-enriched silicon.\nWe observe qubit precession in the inter-site tunnelling regime and assess the\nimpact of qubit transport using Ramsey interferometry and quantum state\ntomography techniques. We report a polarization transfer fidelity of 99.97% and\nan average coherent transfer fidelity of 99.4%. Our results provide key\nelements for high-fidelity, on-chip quantum information distribution, as long\nenvisaged, reinforcing the scaling prospects of silicon-based spin qubits.",
        "positive": "Evolution of the quantum Hall bulk spectrum into chiral edge states: One of the most intriguing and fundamental properties of topological\nmaterials is the correspondence between the conducting edge states and the\ngapped bulk spectrum. So far, it has been impossible to access the full\nevolution of edge states with critical parameters such as magnetic field due to\npoor resolution, remnant bulk conductivity, or disorder. Here, we use a GaAs\ncleaved edge quantum wire to perform momentum-resolved tunneling spectroscopy.\nThis allows us to probe the evolution of the chiral quantum Hall edge states\nand their positions from the sample edge with unprecedented precision from very\nlow magnetic fields all the way to high fields where depopulation occurs. We\npresent consistent analytical and numerical models, inferring the edge states\nfrom the well known bulk spectrum, finding excellent agreement with the\nexperiment -- thus providing direct evidence for the bulk to edge\ncorrespondence. In addition, we observe various features beyond the\nsingle-particle picture, such as Fermi level pinning, exchange-enhanced spin\nsplitting and signatures of edge-state reconstruction."
    },
    {
        "anchor": "Growth dynamics and thickness-dependent electronic structure of\n  topological insulator Bi2Te3 thin films on Si: We use real-time reflection high energy electron diffraction intensity\noscillation to establish the Te-rich growth dynamics of topological insulator\nthin films of Bi2Te3 on Si(111) substrate by molecular beam epitaxy. In situ\nangle resolved photoemission spectroscopy (ARPES), scanning tunneling\nmicroscopy and ex situ transport measurements reveal that the as-grown Bi2Te3\nfilms without any doping are an intrinsic topological insulator with its Fermi\nlevel intersecting only the metallic surface states. Experimentally, we find\nthat the single-Dirac-cone surface state develops at a thickness of two\nquintuple layers (2 QL). Theoretically, we show that the interaction between\nthe surface states from both sides of the film, which is determined by the\npenetration depth of the topological surface state wavefunctions, sets this\nlower thickness limit.",
        "positive": "Modifications of the Lifshitz-Kosevich formula in two-dimensional Dirac\n  systems: Starting from the Luttinger-Ward functional we derive an expression for the\noscillatory part of the grand potential of a two dimensional Dirac system in a\nmagnetic field. We perform the computation for the clean and the disordered\nsystem, and we study the effect of electron-electron interactions on the\noscillations. Unlike in the two dimensional electron gas (2DEG), a finite\ntemperature and impurity scattering also affects the oscillation frequency.\nFurthermore, we find that in graphene, compared to the 2DEG, additional\ninteraction induced damping effects occur: to two-loop order electron-electron\ninteractions do lead to an additional damping factor in the amplitude of the\nLifshitz-Kosevich-formula."
    },
    {
        "anchor": "Single-dopant band bending fluctuations in MoSe$_2$ measured with\n  electrostatic force microscopy: In this work, we experimentally demonstrate two-state fluctuations in a\nmetal-insulator-semiconductor (MIS) device formed out of a metallic atomic\nforce microscopy tip, vacuum gap, and multilayer MoSe$_2$ sample. We show that\nnoise in this device is intrinsically bias-dependent due to the bias-dependent\nsurface potential, and does not require that the frequency or magnitude of\nindividual dopant fluctuations are themselves bias-dependent. Finally, we\nmeasure spatial nonhomogeneities in band bending (charge reorganization)\ntimescales.",
        "positive": "Topological Phase Transitions in Disordered Electric Quadrupole\n  Insulators: We investigate disorder-driven topological phase transitions in quantized\nelectric quadrupole insulators. We show that chiral symmetry can protect the\nquantization of the quadrupole moment $q_{xy}$, such that the higher-order\ntopological invariant is well-defined even when disorder has broken all\ncrystalline symmetries. Moreover, nonvanishing $q_{xy}$ and consequent corner\nmodes can be induced from a trivial insulating phase by disorder that preserves\nchiral symmetry. The critical points of such topological phase transitions are\nmarked by the occurrence of extended boundary states even in the presence of\nstrong disorder. We provide a systematic characterization of these\ndisorder-driven topological phase transitions from both bulk and boundary\ndescriptions."
    },
    {
        "anchor": "Skyrmion size in skyrmion crystals: A magnetic skyrmion is a topological object that can exist as a solitary\nembedded in the vast ferromagnetic phase, or coexists with a group of its\n\"siblings\" in various stripy phases as well as skyrmion crystals (SkXs).\nIsolated skyrmions and skyrmions in an SkX are circular while a skyrmion in\nother phases is a stripe of various forms. Unexpectedly, the sizes of the three\ndifferent types of skyrmions depend on material parameters differently. For\nchiral magnetic films with exchange stiffness constant $A$, the\nDzyaloshinskii-Moriya interaction (DMI) strength $D$, and perpendicular\nmagnetic anisotropy $K$, $\\kappa\\equiv\\pi^2D^2/(16AK)=1$ separates isolated\nskyrmions from condensed skyrmion states. In contrast to isolated skyrmions\nwhose size increases with $D/K$ and is insensitive to $\\kappa\\ll1$ and stripe\nskyrmions whose width increases with $A/D$ and is insensitive to $\\kappa\\gg1$,\nthe size of skyrmions in SkXs is inversely proportional to the square root of\nskyrmion number density and decreases with $A/D$. This finding has important\nimplications in our search for stable smaller skyrmions at the room temperature\nin applications.",
        "positive": "Interlayer coupling in rotationally faulted multilayer graphenes: This article reviews progress in the theoretical modelling of the electronic\nstructure of rotationally faulted multilayer graphenes. In these systems the\ncrystallographic axes of neighboring layers are misaligned so that the layer\nstacking does not occur in the Bernal structure observed in three dimensional\ngraphite and frequently found in exfoliated bilayer graphene. Notably,\nrotationally faulted graphenes are commonly found in other forms of multilayer\ngraphene including epitaxial graphenes thermally grown on ${\\rm SiC \\, (000\n\\bar 1)}$, graphenes grown by chemical vapor deposition, folded mechanically\nexfoliated graphenes, and graphene flakes deposited on graphite. Rotational\nfaults are experimentally associated with a strong reduction of the energy\nscale for coherent single particle interlayer motion. The microscopic basis for\nthis reduction and its consequences have attracted significant theoretical\nattention from several groups that are highlighted in this review."
    },
    {
        "anchor": "Nanostructured electrodes for thermionic and thermo-tunneling devices: Recently, new quantum features have been studied in the area of ridged\nquantum wells (RQW). Periodic ridges on the surface of the quantum well layer\nimpose additional boundary conditions on the electron wave function and reduce\nthe quantum state density. Electrons, rejected from forbidden quantum states,\nhave to occupy the states with higher energy. As a result, Fermi energy in RQW\nincreases and work function (WF) decreases. We investigate low WF electrode,\ncom-posed from a metal RQW layer and a base substrate. The substrate material\nwas selected so that electrons were confined to the RQW. The WF value depends\non ridge geometry and electron confinement. We calculate WF in the metal RQW\nfilms grown both on a semiconductor and metal substrates. In the case of\nsemiconductor substrate, wide band gap materials are preferable as they allow\nmore reduction in RQW work function. In the case of metal substrate, low Fermi\nenergy materials are preferable. For most material pairs, the WF was reduced\ndramatically. Such structures, can serve as electrodes for room temperature\nthermionic and thermotunnel energy converters and coolers.",
        "positive": "Can freestanding Xene monolayers behave as excitonic insulators?: We predict a phase transition in freestanding monolayer Xenes from the\nsemiconducting phase to the excitonic insulating (EI) phase can be induced by\nreducing an external electric field below some critical value which is unique\nto each material. The splitting of the conduction and valence bands due to\nspin-orbit coupling at non-zero electric fields leads to the formation of $A$\nand $B$ excitons in the larger or smaller band gap, with correspondingly larger\nor smaller binding energies. Our calculations show the coexistence of the\nsemiconducting phase of $A$ excitons with the EI phase of $B$ excitons for a\nparticular range of electric field. The dielectric environment precludes the\nexistence of the EI phase in supported or encapsulated monolayer Xenes."
    },
    {
        "anchor": "Biexciton-mediated superradiant photon blockade: The photon blockade is a hallmark of quantum light transport through a single\ntwo-level system that can accomodate only one photon. Here, we theoretically\nshow that two-photon transmission can be suppressed even for a seemingly\nclassical system with large number of quantum dots in a cavity when the\nbiexciton nonlinearity is taken into account. We reveal the nonmonotonous\ndependence of the second-order correlation function of the transmitted photons\non the biexciton binding energy. The blockade is realized by proper tuning the\nbiexciton resonance that controls the collective superradiant modes.",
        "positive": "Dual-probe spectroscopic fingerprints of defects in graphene: Recent advances in experimental techniques emphasize the usefulness of\nmultiple scanning probe techniques when analyzing nanoscale samples. Here, we\nanalyze theoretically dual-probe setups with probe separations in the nanometer\nrange, i.e., in a regime where quantum coherence effects can be observed at low\ntemperatures. In a dual-probe setup the electrons are injected at one probe and\ncollected at the other. The measured conductance reflects the local transport\nproperties on the nanoscale, thereby yielding information complementary to that\nobtained with a standard one-probe setup (the local density-of-states). In this\nwork we develop a real space Green's function method to compute the\nconductance. This requires an extension of the standard calculation schemes,\nwhich typically address a finite sample between the probes. In contrast, the\ndeveloped method makes no assumption on the sample size (e.g., an extended\ngraphene sheet). Applying this method, we study the transport anisotropies in\npristine graphene sheets, and analyze the spectroscopic fingerprints arising\nfrom quantum interference around single-site defects, such as vacancies and\nadatoms. Furthermore, we demonstrate that the dual-probe setup is a useful tool\nfor characterizing the electronic transport properties of extended defects or\ndesigned nanostructures. In particular, we show that nanoscale perforations, or\nantidots, in a graphene sheet display Fano-type resonances with a strong\ndependence on the edge geometry of the perforation."
    },
    {
        "anchor": "Two-Dimensional Electron-Hole Systems in a Strong Magnetic Field:\n  Composite Fermion Picture for Multi-Component Plasmas: Electron-hole systems on a Haldane sphere are studied by exact numerical\ndiagonalization. Low lying states contain one or more types of bound charged\nexcitonic complexes Xk-, interacting through appropriate pseudopotentials.\nIncompressible ground states of such multi-component plasmas are found. A\ngeneralized multi-component Laughlin wavefunction and composite Fermion picture\nare shown to predict the low lying states of an electron-hole gas at any value\nof the magnetic field.",
        "positive": "Prediction of a Weyl Semimetal in Hg$_{1-x-y}$Cd$_x$Mn$_y$Te: We study strained Hg$_{1-x-y}$Cd$_x$Mn$_y$Te in a magnetic field using a\n$\\bm{k}\\cdot\\bm{p}$ model and predict that the system is a Weyl semimetal with\ntwo nodes in an experimentally reasonable region of the phase diagram. We also\npredict two signatures of the Weyl semimetal phase which arise from tunability\nof the Weyl node splitting. First, we find that the Hall conductivity is\nproportional to the average Mn ion spin and thus is strongly temperature\ndependent. Second, we find an unusual magnetic field angle dependence of the\nHall conductivity; in particular, we predict a peak in $\\sigma_{xy}$ as a\nfunction of field angle in the $xz$-plane and a finite $\\sigma_{yz}$ as the\n$x$-component of the field goes to 0."
    },
    {
        "anchor": "Formation of defects in multirow Wigner crystals: We study the structural properties of a quasi-one-dimensional classical\nWigner crystal, confined in the transverse direction by a parabolic potential.\nWith increasing density, the one-dimensional crystal first splits into a zigzag\ncrystal before progressively more rows appear. While up to four rows the ground\nstate possesses a regular structure, five-row crystals exhibit defects in a\ncertain density regime. We identify two phases with different types of defects.\nFurthermore, using a simplified model, we show that beyond nine rows no stable\nregular structures exist.",
        "positive": "The effects of dissipation on topological mechanical systems: We theoretically study the effects of isotropic dissipation in a topological\nmechanical system which is an analogue of Chern insulator in mechanical\nvibrational lattice. The global gauge invariance is still conserved in this\nsystem albeit it is destroyed by the dissipation in the quantum counterpart.\nThe chiral edge states in this system are therefore robust against strong\ndissipation. The dissipation also causes a dispersion of damping for the\neigenstates. It will modify the equation of motion of a wave packet by an extra\neffective force. After taking into account the Berry curvature in the wave\nvector space, the trace of a free wave packet in the real space should be\ncurved, feinting to break the Newton's first law."
    },
    {
        "anchor": "Phase diagram of 2D array of mesoscopic granules: A lattice boson model is used to study ordering phenomena in regular 2D array\nof superconductive mesoscopic granules, Josephson junctions or pores filled\nwith a superfluid helium. Phase diagram of the system, when quantum\nfluctuations of both the phase and local superfluid density are essential, is\nanalyzed both analytically and by quantum Monte Carlo technique. For the system\nof strongly interacting bosons it is found that as the boson density $n_0$ is\nincreased the boundary of ordered superconducting state shifts to {\\it lower\ntemperatures} and at $n_0 > 8$ approaches its limiting position corresponding\nto negligible relative fluctuations of moduli of the order parameter (as in an\narray of \"macroscopic\" granules). In the region of weak quantum fluctuations of\nphases mesoscopic phenomena manifest themselves up to $n_0 \\sim 10$. The mean\nfield theory and functional integral $1/n_0$ - expansion results are shown to\nagree with that of quantum Monte Carlo calculations of the boson Hubbard model\nand its quasiclassical limit, the quantum XY model.",
        "positive": "Conductivity Corrections for Topological Insulators with Spin-Orbit\n  Impurities: A New Hikami-Larkin-Nagaoka Formula: The Hikami-Larkin-Nagaoka (HLN) formula [Prog. Theor. Phys. 63, 707 (1980)]\ndescribes the quantum corrections to the magnetoconductivity of a quasi-2D\nelectron gas (quasi-2DEG) with parabolic dispersion. It predicts a crossover\nfrom weak localization to antilocalization as a function of the strength of\nscattering off spin-orbit impurities. Here, we derive the conductivity\ncorrection for massless Dirac fermions in 3D topological insulators (TIs) in\nthe presence of spin-orbit impurities. We show that this correction is always\npositive and therefore we predict weak antilocalization for every value of the\nspin-orbit disorder. Furthermore, the correction to the diffusion constant is\nsurprisingly linear in the strength of the impurity spin-orbit. Our results\ncall for a reinterpretation of experimental fits for the magnetoconductivity of\n3D TIs which have so far used the standard HLN formula."
    },
    {
        "anchor": "On the possibility of a terahertz light emitting diode based on a\n  dressed quantum well: We consider theoretically the realization of a tunable terahertz light\nemitting diode from a quantum well with dressed electrons placed in a highly\ndoped p-n junction. In the considered system the strong resonant dressing field\nforms dynamic Stark gaps in the valence and conduction bands and the electric\nfield inside the p-n junction makes the QW asymmetric. It is shown that the\nelectrons transiting through the light induced Stark gaps in the conduction\nband emit photons with energy directly proportional to the dressing field. This\nscheme is tunable, compact, and shows a fair efficiency.",
        "positive": "Terahertz photodetection in scalable single-layer-graphene and hexagonal\n  boron nitride heterostructures: The unique optoelectronic properties of single layer graphene (SLG) are ideal\nfor the development of photonic devices across a broad range of frequencies,\nfrom X-rays to microwaves. In the terahertz (THz) range (0.1-10 THz frequency)\nthis has led to the development of optical modulators, non-linear sources, and\nphotodetectors, with state-of-the-art performances. A key challenge is the\nintegration of SLG-based active elements with pre-existing technological\nplatforms in a scalable way, while maintaining performance level unperturbed.\nHere, we report on the development of room temperature THz detection in\nlarge-area SLG, grown by chemical vapor deposition (CVD), integrated in\nantenna-coupled field effect transistors. We selectively activate the\nphoto-thermoelectric detection dynamics, and we employ different dielectric\nconfigurations on SLG on Al2O3 with and without large-area CVD hBN capping to\ninvestigate their effect on SLG thermoelectric properties underpinning\nphotodetection. With these scalable architectures, response times ~5ns and\nnoise equivalent powers ~1nWHz-1/2 are achieved under zero-bias operation. This\nshows the feasibility of scalable, large-area, layered materials\nheterostructures for THz detection."
    },
    {
        "anchor": "Conductance transition with interacting bosons in an Aharonov-Bohm cage: We study transport of interacting bosons through an Aharonov-Bohm cage - a\nbuilding block of flat band networks - with coherent pump and sink leads. In\nthe absence of interactions the cage is insulating due to destructive\ninterference. We find that the cage stays insulating up to a critical value of\nthe pump strength in the presence of mean field interactions, while the quantum\nregime induces particle pair transport and weak conductance below the critical\npump strength. A swift crossover from quantum into the classical regime upon\nfurther pump strength increase is observed. We solve the time dependent master\nequations for the density matrix of the many body problem both in the\nclassical, pure quantum, and pseudoclassical regimes. We start with an empty\ncage and switch on driving. We characterize the transient dynamics, and the\ncomplexity of the resulting steady states and attractors. Our results can be\nreadily realized using experimental platforms involving interacting ultracold\natoms and photons on finetuned optical lattices.",
        "positive": "Negative nonlinear damping of a graphene mechanical resonator: We experimentally investigate the nonlinear response of a multilayer graphene\nresonator using a superconducting microwave cavity to detect its motion. The\nradiation pressure force is used to drive the mechanical resonator in an\noptomechanically induced transparency configuration. By varying the amplitudes\nof drive and probe tones, the mechanical resonator can be brought into a\nnonlinear limit. Using the calibration of the optomechanical coupling, we\nquantify the mechanical Duffing nonlinearity. By increasing the drive force, we\nobserve a decrease in the mechanical dissipation rate at large amplitudes,\nsuggesting a negative nonlinear damping mechanism in the graphene resonator.\nIncreasing the optomechanical backaction, we observe a nonlinear regime not\ndescribed by a Duffing response that includes new instabilities of the\nmechanical response."
    },
    {
        "anchor": "Non-Hermitian skin effect induced by Rashba-Dresselhaus spin-orbit\n  coupling: 1D chains with non-reciprocal tunneling realizing the non-Hermitian skin\neffect (NHSE) have attracted considerable interest in the last years whereas\ntheir experimental realization in real space remains limited to a few examples.\nIn this work, we propose a new generic way of implementing non-reciprocity\nbased on a combination of the Rashba-Dresshlauss spin-orbit coupling, existing\nfor electrons, cold atoms, and photons, and a lifetime imbalance between two\nspin components. We show that one can realize the Hatano-Nelson model, the\nnon-Hermitian Su-Schrieffer-Heeger model, and even observe the NHSE in a 1D\npotential well without the need for a lattice. We further demonstrate the\npractical feasibility of this proposal by considering the specific example of a\nphotonic liquid crystal microcavity. This platform allows one to switch on and\noff the NHSE by applying an external voltage to the microcavity.",
        "positive": "Edge modes in the fractional quantum Hall effect without extra edge\n  fermions: We show that the Chern-Simons-Landau-Ginsburg theory that describes the\nquantum Hall effect on a bounded sample is anomaly free and thus does not\nrequire the addition of extra chiral fermions on the boundary to restore local\ngauge invariance."
    },
    {
        "anchor": "Using weak measurements to extract the $Z_2$ index of a topological\n  insulator: Recently there has been an interest in applying the concept of weak values\nand weak measurements to condensed matter systems. Here a weak measurement\nprotocol is proposed for obtaining the $Z_2$ index of a topological insulator.\nThe setup consists of a topological insulator with a hole pierced by a time\ndependent Aharonov-Bohm flux. A certain weak value ($A_{gs}$) associated with\nthe time-integrated magnetization in the hole has a universal response to a\nsmall ambient magnetic field ($B$), namely $A_{gs}B = 2 \\hbar$. This result is\nunaffected by disorder, interactions, and, to a large extent, the speed of the\nflux threading. It hinges mainly on preventing the flux from leaking outside\nthe hole, as well as being able to detect magnetization at a resolution of a\nfew spins. A similar result may be obtained using only charge measurements, in\na setup consisting of a double quantum dot weakly coupled to an LC circuit.\nHere one obtains $\\langle \\phi \\rangle_{weak} Q_0 =2\\hbar$, where $\\langle \\phi\n\\rangle_{weak}$ is a weak value associated with the flux on the inductor and\n$Q_0$ is the average capacitor charging. The universality of these results\nsuggests that they may be used as a testbed for weak values in condensed matter\nphysics.",
        "positive": "Quantum Entanglement of Flux Qubits via a Resonator: We show that flux qubits can be efficiently entangled by inductive coupling\nto a tunable resonant circuit, in the scheme reminiscent of atoms' entanglement\nthrough the optical cavity mode. It is shown, in particular, that the\nsingle-photon excitation of the resonator produces the pure Bell state of\nqubits with the completely disentangled LC circuit."
    },
    {
        "anchor": "Topological quantization of boundary forces and the integrated density\n  of states: For quantum systems described by Schr\\\"odinger operators on the half-space\n$\\RR^{d-1}\\times\\RR^{leq 0}$ the boundary force per unit area and unit energy\nis topologically quantised provided the Fermi energy lies in a gap of the bulk\nspectrum. Under this condition it is also equal to the integrated density of\nstates at the Fermi energy.",
        "positive": "Superconducting proximity effect on a two-dimensional Dirac electron\n  system: The superconducting proximity effect on two-dimensional massless Dirac\nelectrons is usually analyzed using a simple model consisting of the Dirac\nHamiltonian and an energy-independent pair potential. Although this\nconventional model is plausible, it is questionable whether it can fully\ndescribe the proximity effect from a superconductor. Here, we derive a more\ngeneral proximity model starting from an appropriate microscopic model for the\nDirac electron system in planar contact with a superconductor. The resulting\nmodel describes the proximity effect in terms of the energy-dependent pair\npotential and renormalization term. Within this framework, we analyze the\ndensity of states, the quasiparticle wave function, and the charge conservation\nof Dirac electrons. The result reveals several characteristic features of the\nproximity effect, which cannot be captured within the conventional model."
    },
    {
        "anchor": "Mesoscopic Physics and Nanoelectronics: Electronic transport properties through some model quantum systems are\nre-visited. A simple tight-binding framework is given to describe the systems\nwhere all numerical calculations are made using the Green's function formalism.\nFirst, we demonstrate electronic transport in four different polycyclic\nhydrocarbon molecules, namely, benzene, napthalene, anthracene and tetracene.\nIt is observed that electron conduction through these molecular wires is highly\nsensitive to molecule-to-electrode coupling strength and quantum interference\nof electronic waves passing through different branches of the molecular ring.\nOur investigations predict that to design a molecular electronic device, in\naddition to the molecule itself, both the molecular coupling and\nmolecule-to-electrode interface geometry are highly important. Next, we make an\nin-depth study to design classical logic gates with the help of simple\nmesoscopic rings, based on the concept of Aharonov-Bohm effect. A single\nmesoscopic ring or two such rings are used to establish the logical operations\nwhere the key controlling parameter is the magnetic flux threaded by the ring.\nThe analysis might be helpful in fabricating meso-scale or nano-scale logic\ngates. Finally, we address multi-terminal quantum transport through a single\nbenzene molecule using Landauer-B\\\"{u}ttiker formalism. Quite interestingly we\nsee that a three-terminal benzene molecule can be operated as an electronic\ntransistor and this phenomenon is justified through current-voltage\ncharacteristics. All these essential features of electron transport may provide\na basic theoretical framework to examine electron conduction through any\nmulti-terminal quantum system.",
        "positive": "Joule heating and the thermal conductivity of a two-dimensional electron\n  gas at cryogenic temperatures studied by modified 3$\u03c9$ method: During the standard ac lock-in measurement of the resistance of a\ntwo-dimensional electron gas (2DEG) applying an ac current $I = \\sqrt{2} I_0\n\\sin(\\omega t)$, the electron temperature $T_e$ oscillates with the angular\nfrequency $2 \\omega$ due to the Joule heating $\\propto I^2$. We have shown that\nthe highest ($T_\\mathrm{H}$) and the lowest ($T_\\mathrm{L}$) temperatures\nduring a cycle of the oscillations can be deduced, at cryogenic temperatures,\nexploiting the third-harmonic (3$\\omega$) component of the voltage drop\ngenerated by the ac current $I$ and employing the amplitude of the Shubnikov-de\nHaas oscillations as the measure of $T_e$. The temperatures $T_\\mathrm{H}$ and\n$T_\\mathrm{L}$ thus obtained allow us to roughly evaluate the thermal\nconductivity $\\kappa_{xx}$ of the 2DEG via the modified 3$\\omega$ method, in\nwhich the method originally devised for bulk materials is modified to be\napplicable to a 2DEG embedded in a semiconductor wafer. The $\\kappa_{xx}$ thus\ndeduced is found to be consistent with the Wiedemann-Franz law. The method\nprovides a convenient way to access $\\kappa_{xx}$ using only a standard\nHall-bar device and the simple experimental setup for the resistance\nmeasurement."
    },
    {
        "anchor": "Electrical Image Potential and Solvation Energies for an Ion in a Pore\n  in a Metallic Electrode or in a Nanotube: Electrical image potentials can be important in small spaces, such as\nnanoscale pores in porous electrodes, which are used in capacitive desalination\nand in supercapacitors. It will be shown here that inside pores in porous\nmetallic materials the image potentials can be considerably larger than near\nflat walls, as a result of the fact that the dielectric constant for an\nelectric field perpendicular to a wall is much smaller than the bulk dielectric\nconstant of water. Calculations will be presented for the image potential in\nspherical and cylindrically shaped pores. The calculations for cylindrical\npores can also be applied to nanotubes. It was believed for a long time, on the\nbasis of molecular dynamics simulations, that in order to push a salt solution\nthrough a small radius nanotube, work must be done against the solvation energy\nof the ions, which is larger inside a narrow nanotube than it is in the bulk.\nThe relatively large image charge potential energy in narrow nanotubes,\nhowever, tends to oppose this increase in the solvation energy. The degree to\nwhich the image potential facilitates the flow of the salt ions into nanotubes\nwill be discussed.",
        "positive": "Propagation and imaging of mechanical waves in a highly-stressed\n  single-mode phononic waveguide: We demonstrate a single-mode phononic waveguide that enables robust\npropagation of mechanical waves. The waveguide is a highly-stressed silicon\nnitride membrane that supports the propagation of out-of-plane modes. In direct\nanalogy to rectangular microwave waveguides, there exists a band of frequencies\nover which only the fundamental mode is allowed to propagate, while multiple\nmodes are supported at higher frequencies. We directly image the mode profiles\nusing optical heterodyne vibration measurement, showing good agreement with\ntheory. In the single-mode frequency band, we show low-loss propagation\n($\\sim1$~dB/cm) for a $\\sim5$~MHz mechanical wave. This design is well suited\nfor phononic circuits interconnecting elements such as non-linear resonators or\noptomechanical devices for signal processing, sensing or quantum technologies."
    },
    {
        "anchor": "Resonance Plasmon Linewidth Oscillations in Spheroidal Metallic\n  Nanoparticle Embedded in a Dielectric Matrix: The kinetic approach is applied to calculate oscillations of a surface\nplasmon linewidth in a spheroidal metal nanoparticle embedded in any dielectric\nmedia. The principal attention is focused on the case, when the free electron\npath is much greater than the particle size.\n  The linewidth of the plasmon resonance as a function of the particle radius,\nshape, dielectric constant of the surrounding medium, and the light frequency\nis studied in detail. It is found that the resonance plasmon linewidth\noscillates with increasing both the particle size and the dielectric constant\nof surrounding medium.\n  The main attention is paid to the electron surface-scattering contribution to\nthe plasmon decay.\n  All calculations the plasmon resonance linewidth are illustrated by the\nexample of the Na nanoparticles with different radii.\n  The results obtained in the kinetic approach are compared with the known ones\nfrom other models.\n  The role of the radiative damping is discussed as well.",
        "positive": "Electronic structure and quantum transport in twisted bilayer graphene\n  with resonant scatterers: Staking layered materials revealed to be a very powerful method to tailor\ntheir electronic properties. It has indeed been theoretically and\nexperimentally shown that twisted bilayers of graphene (tBLG) with a rotation\nangle $\\theta$, forming Moir\\'e pattern, confine electrons in a tunable way as\na function of $\\theta$. Here, we study electronic structure and transport in\ntBLG using tight-binding numerical calculations in commensurate twisted bilayer\nstructures and a pertubative continuous theory, which is valid for not too\nsmall angles ($\\theta > \\sim 2^\\circ $). This two approaches allow to\nunderstand the effect of $\\theta$ on the local density of states, the electron\nlifetime due to disorder, the dc-conducitivity and the quantum correction of\nthe conductivity due to multiple scattering effects. We distinguished the cases\nwhere disorder is equaly distributed in the two layer or only in one layer.\nWhen only one layer is disordered, diffusion properties depends strongly on\n$\\theta$, showing thus the effect of Moir\\'e electronic localisation at\nintermediate angles, $\\sim 2^\\circ < \\theta < \\sim 20^\\circ$."
    },
    {
        "anchor": "Two-dimensional semimetal in HgTe quantum well under hydrostatic\n  pressure: We report results of systematic measurements of charge transport properties\nof the 20.5nm wide HgTe-based quantum well in perpendicular magnetic field,\nperformed under hydrostatic pressures up to 15.1 kbar. At ambient pressure\ntransport is well described by the two-band semiclassical model.In contrast, at\nelevated pressure, we observed non-monotonic pressure dependence of resistivity\nat CNP. For pressures lower than $\\approx9$ kbar, resistivity grows with\npressure, in accord with expectations from the band structure calculations and\nthe model incorporating effects of disorder on transport in 2D semimetals with\nindirect band overlap. For higher pressures, the resistivity saturates and\nstarts decreasing upon further increase of pressure. Above $\\approx14$ kbar the\nresistance and hopping transport character sharply change, which may indicate\nformation of the excitonic insulator state. The data also reveals strong\ninfluence of disorder on transport in 2D electron-hole system with a small band\noverlap.",
        "positive": "Forster energy transfer signatures in optically driven quantum dot\n  molecules: The Forster resonant energy transfer mechanism (FRET) is investigated in\noptically driven and electrically gated tunnel coupled quantum dot molecules.\nTwo novel FRET induced optical signatures are found in the dressed excitonic\nspectrum. This is constructed from exciton level occupation as function of pump\nlaser energy and applied bias, resembling a level anticrossing spectroscopy\nmeasurement. We observe a redistribution of spectral weight and splitting of\nthe exciton spectral lines. FRET among single excitons induces a splitting in\nthe spatially-direct exciton lines, away from the anticrossing due to charge\ntunneling in the molecule. However, near the anticrossing, a novel signature\nappears as a weak satellite line following an indirect exciton line. FRET\nsignatures may also occur among indirect excitons, appearing as split indirect\nlines. In that case, the signatures appear also in the direct biexciton states,\nas the indirect satellite mixes in near the tunneling anticrossing region."
    },
    {
        "anchor": "Breakdown of the static dielectric screening approximation of Coulomb\n  interactions in atomically thin semiconductors: Coulomb interactions in atomically thin materials are uniquely sensitive to\nvariations in the dielectric screening of the environment, which can be used to\ncontrol quasiparticles and exotic quantum many-body phases. A static\napproximation of the dielectric response, where increased dielectric screening\nis predicted to cause an energy redshift of the exciton resonance, has been\nuntil now sufficient. Here, we use charge-tunable exciton resonances to study\nscreening effects in transition metal dichalcogenide monolayers embedded in\nmaterials with dielectric constants ranging from 4 to more than 1000. In\ncontrast to expectations, we observe a blueshift of the exciton resonance\nexceeding 30 meV for larger dielectric constant environments. By employing a\ndynamical screening model, we find that while the exciton binding energy\nremains mostly controlled by the static dielectric response, the exciton\nself-energy is dominated by the high-frequency response. Dielectrics with\nmarkedly different static and high-frequency screening enable the selective\naddressing of distinct many-body effects in layered materials and their\nheterostructures, expanding the tunability range and offering new routes to\ndetect and control correlated quantum many-body states and to design\noptoelectronic and quantum devices.",
        "positive": "Supercurrent carried by non-equlibrium quasiparticles in a multiterminal\n  Josephson junction: We theoretically study coherent multiple Andreev reflections in a biased\nthree-terminal Josephson junction. We demonstrate that the direct current\nflowing through the junction consists of supercurrent components when the bias\nvoltages are commensurate. This dissipationless current depends on the phase in\nthe superconducting leads and stems from the Cooper pair transfer processes\ninduced by non-local Andreev reflections of the quasiparticles originating from\nthe superconducting leads. We identify supercurrent-enhanced lines in the\ncurrent and conductance maps of the recent measurement [Y. Cohen, et al., PNAS\n115, 6991 (2018)] on a nanowire Josephson junction and show that the magnitude\nof the phase-dependent current components is proportional to the junction\ntransparency with the power corresponding to the component order."
    },
    {
        "anchor": "Longitudinal magnetoconductivity and magnetodielectric effect in bilayer\n  graphene: It was recently shown that a finite imbalance between electron densities in\nthe $\\mathbf{K}$ and $\\mathbf{K}'$ valleys of bilayer graphene induces a\nmagnetoelectric coupling. Here we explore ramifications of this electronically\ntunable magnetoelectric effect for the optical conductivity and dielectric\npermittivity of this material. Our results augment current understanding of\nlongitudinal magnetoresistance and magnetocapacitance in unconventional\nmaterials.",
        "positive": "Phonon-dressed Mollow triplet in the regime of cavity-QED: We study the resonance fluorescence spectra of a driven quantum dot placed\ninside a high $Q$ semiconductor cavity and interacting with an acoustic phonon\nbath. The dynamics is calculated using a time-convolutionless master equation\nobtained in the polaron frame. We demonstrate pronounced spectral broadening of\nthe Mollow sidebands through cavity-emission which, for small cavity-coupling\nrates, increases quadratically with the Rabi frequency. However, for larger\ncavity coupling rates, this broadening dependence is found to be more complex.\nThis field-dependent Mollow triplet broadening is primarily a consequence of\nthe triplet peaks sampling different parts of the asymmetric phonon bath, and\nagrees directly with recent experiments with semiconductor micropillars. The\ninfluence from the detuned cavity photon bath and multi-photon effects is shown\nto play a qualitatively important role on the fluorescence spectra."
    },
    {
        "anchor": "Energy levels of a two-dimensional hydrogen atom with spin-orbit Rashba\n  interaction: Electronic bound states around charged impurities in two-dimensional systems\nwith structural inversion asymmetry can be described in terms of a\ntwo-dimensional hydrogen atom in the presence of a Rashba spin-orbit\ninteraction. Here, the energy levels of the bound electron are evaluated\nnumerically as a function of the spin-orbit interaction, and analytic\nexpressions for the weak and strong spin-orbit coupling limits are compared\nwith the numerical results. It is found that, besides the level splitting due\nto the lack of inversion symmetry, the energy levels are lowered for\nsufficiently strong spin-orbit coupling, indicating that the electron gets more\ntightly bound to the ion as the spin-orbit interaction increases. Similarities\nand differences with respect to the two-dimensional Fr\\\"ohlich polaron with\nRashba coupling are discussed.",
        "positive": "Effect of flux-dependent Friedel oscillations upon the effective\n  transmission of an interacting nano-system: We consider a nano-system connected to measurement probes via non interacting\nleads. When the electrons interact inside the nano-system, the coefficient\n|ts(E_F)|^2 describing its effective transmission at the Fermi energy E_F\nceases to be local. This effect of electron-electron interactions upon\n|ts(E_F)|^2 is studied using a one dimensional model of spinless fermions and\nthe Hartree-Fock approximation. The non locality of |ts(E_F)|^2 is due to the\ncoupling between the Hartree and Fock corrections inside the nano-system and\nthe scatterers outside the nano-system via long range Friedel oscillations.\nUsing this phenomenon, one can vary |ts(E_F)|^2 by an Aharonov-Bohm flux\nthreading a ring which is attached to one lead at a distance Lc from the\nnano-system. For small distances Lc, the variation of the quantum conductance\ninduced by this non local effect can exceed 0.1 (e^2/h)."
    },
    {
        "anchor": "Electron-nuclear dynamics in a quantum dot under non-unitary electron\n  control: We introduce a method for solving the problem of an externally controlled\nelectron spin in a quantum dot interacting with host nuclei via the hyperfine\ninteraction. Our method accounts for generalized (non-unitary) evolution\neffected by external controls and the environment, such as coherent lasers\ncombined with spontaneous emission. As a concrete example we develop the\nmicroscopic theory of the dynamics of nuclear-induced frequency focusing, as\nfirst measured in Science 317, 1896 (2007); we find that the nuclear relaxation\nrates are several orders of magnitude faster than those quoted in that work.",
        "positive": "Microwave spectroscopic observation of a Wigner solid within the 1/2\n  fractional quantum Hall effect: The fractional quantum Hall effect (FQHE) states at half integer Landau\nfillings ($\\nu$) have long been of great interest, since they have correlations\nthat differ from those of the fundamental Laughlin states found at odd\ndenominators. At $\\nu=1/2$ the FQHE has been observed in wide or double quantum\nwells, and is ascribed to the two-component Halperin-Laughlin $\\Psi_{331}$\nstate. $\\Psi_{331}$ excitations carry charge $\\pm e/4$, like the carriers of\n$\\nu=5/2$ states which are of interest in quantum computation. Further, such an\nexcitation (quasiparticle or -hole) of $\\Psi_{331}$ has unequal, opposite\ncharge in the top and bottom layers, and hence an up or down dipole moment.\nHere we report evidence for a Wigner solid (WS) of such dipolar quasiholes from\na quantitative study of the microwave spectra of a wide quantum well (WQW) at\n$\\nu$ close to 1/2."
    },
    {
        "anchor": "Coherent single electron spin control in a slanting Zeeman field: We consider a single electron in a 1D quantum dot with a static slanting\nZeeman field. By combining the spin and orbital degrees of freedom of the\nelectron, an effective quantum two-level (qubit) system is defined. This\npseudo-spin can be coherently manipulated by the voltage applied to the gate\nelectrodes, without the need for an external time-dependent magnetic field or\nspin-orbit coupling. Single qubit rotations and the C-NOT operation can be\nrealized. We estimated relaxation ($T_1$) and coherence ($T_{2}$) times, and\nthe (tunable) quality factor. This scheme implies important experimental\nadvantages for single electron spin control.",
        "positive": "Magnetic field induced transition in a wide parabolic well superimposed\n  with superlattice: We study a $Al_{x}Ga_{x-1}As$ parabolic quantum wells (PQW) with\n$GaAs/Al_{x}Ga_{x-1}As$ square superlattice. The magnetotransport in PQW with\nintentionally disordered short-period superlattice reveals a surprising\ntransition from electrons distribution over whole parabolic well to\nindependent-layer states with unequal density. The transition occurs in the\nperpendicular magnetic field at Landau filling factor $\\nu\\approx3$ and is\nsignaled by the appearance of the strong and developing fractional quantum Hall\n(FQH) states and by the enhanced slope of the Hall resistance. We attribute the\ntransition to the possible electron localization in the x-y plane inside the\nlateral wells, and formation of the FQH states in the central well of the\nsuperlattice, driven by electron-electron interaction."
    },
    {
        "anchor": "Statistics of charge transfer in a tunnel junction coupled to an\n  oscillator: The charge transfer statistics of a tunnel junction coupled to a quantum\nobject is studied using the charge projection technique. The joint dynamics of\nthe quantum object and the number of charges transferred through the junction\nis described by the charge specific density matrix. The method allows\nevaluating the joint probability distribution of the state of the quantum\nobject and the charge state of the junction.The statistical properties of the\njunction current are derived from the charge transfer statistics using the\nmaster equation for the charge specific density matrix. The theory is applied\nto a nanoelectromechanical system, and the influence on the average current and\nthe current noise of the junction is obtained for coupling to a harmonic\noscillator.",
        "positive": "The Effect of Interaction on Shot Noise in The Quantum Limit: We employ a non-linear sigma model defined on a Keldysh contour to study the\ncurrent and the current noise in a diffusive micro-bridge in the presence of\nelectron-electron interactions. Out of equilibrium the fluctuation-dissipation\ntheorem (FDT) does not apply, hence these two quantities are not simply\ninterrelated. For a two-dimensional electron gas (2DEG) we obtain logarithmic\nsingularities in the low frequency limit. PACS Nos. 71.10.Ay, 71.23.An,\n73.50.Td"
    },
    {
        "anchor": "Quantum simulation of a Fermi-Hubbard model using a semiconductor\n  quantum dot array: Interacting fermions on a lattice can develop strong quantum correlations,\nwhich lie at the heart of the classical intractability of many exotic phases of\nmatter. Seminal efforts are underway in the control of artificial quantum\nsystems, that can be made to emulate the underlying Fermi-Hubbard models.\nElectrostatically confined conduction band electrons define interacting quantum\ncoherent spin and charge degrees of freedom that allow all-electrical\npure-state initialisation and readily adhere to an engineerable Fermi-Hubbard\nHamiltonian. Until now, however, the substantial electrostatic disorder\ninherent to solid state has made attempts at emulating Fermi-Hubbard physics on\nsolid-state platforms few and far between. Here, we show that for gate-defined\nquantum dots, this disorder can be suppressed in a controlled manner. Novel\ninsights and a newly developed semi-automated and scalable toolbox allow us to\nhomogeneously and independently dial in the electron filling and\nnearest-neighbour tunnel coupling. Bringing these ideas and tools to fruition,\nwe realize the first detailed characterization of the collective Coulomb\nblockade transition, which is the finite-size analogue of the\ninteraction-driven Mott metal-to-insulator transition. As automation and device\nfabrication of semiconductor quantum dots continue to improve, the ideas\npresented here show how quantum dots can be used to investigate the physics of\never more complex many-body states.",
        "positive": "Adiabatically switched-on electrical bias in continuous systems, and the\n  Landauer-Buttiker formula: Consider a three dimensional system which looks like a cross-connected pipe\nsystem, i.e. a small sample coupled to a finite number of leads. We investigate\nthe current running through this system, in the linear response regime, when we\nadiabatically turn on an electrical bias between leads. The main technical tool\nis the use of a finite volume regularization, which allows us to define the\ncurrent coming out of a lead as the time derivative of its charge. We finally\nprove that in virtually all physically interesting situations, the conductivity\ntensor is given by a Landauer-B{\\\"u}ttiker type formula."
    },
    {
        "anchor": "Role of phonon skew scattering in the spin Hall effect of platinum: We measure and analyze the effective spin Hall angle of platinum in the low\nresidual resistivity regime by second harmonic measurements of the spin-orbit\ntorques for a multilayer of Pt/Co/AlO$_x$. An angular dependent study of the\ntorques allows us to extract the effective spin Hall angle responsible for the\ndamping-like torque in the system. We observe a strikingly non-monotonic and\nreproducible temperature dependence of the torques. This behavior is compatible\nwith recent theoretical predictions which include both intrinsic and extrinsic\n(impurities and phonons) contributions to the spin Hall effect at finite\ntemperature.",
        "positive": "Carbon nanotube sensor for vibrating molecules: The transport properties of a CNT capacitively coupled to a molecule\nvibrating along one of its librational modes are studied and its transport\nproperties analyzed in the presence of an STM tip. We evaluate the linear\ncharge and thermal conductances of the system and its thermopower. They are\ndominated by position-dependent Franck-Condon factors, governed by a\nposition-dependent effective coupling constant peaked at the molecule position.\nBoth conductance and thermopower allow to extract some information on the\nposition of the molecule along the CNT. Crucially, however, thermopower sheds\nalso light on the vibrational levelspacing, allowing to obtain a more complete\ncharacterization of the molecule even in the linear regime."
    },
    {
        "anchor": "Resonant-State Expansion of the Fano Peak in Open Quantum Systems: We describe the Fano asymmetry by expanding the transmission amplitude with\nrespect to states with point spectra (discrete eigenstates), including not only\nbound states but also resonant states with complex eigenvalues. We first\nintroduce a novel complete set that spans the Hilbert space of the central part\nof an open quantum-dot system. This complete set contains all states of point\nspectra, but does not contain any states of continuous spectra. We thereby\nanalytically expand the conductance of the dot in terms of all discrete states\nwithout any background integrals. This expansion implies that the resonant\nstates produce the main contributions to the electron transmission. We then\nexplain the Fano peak as an interference effect involving resonant states. We\nfind that there are three types of Fano asymmetry according to their origins:\nthe interference between a resonant state and an anti-resonant state, that\nbetween a resonant state and a bound state, and that between two resonant\nstates. We derive microscopic expressions of the Fano parameters that describe\nthe three types of Fano asymmetry. We show that the last two types display the\nasymmetric energy dependence given by Fano, but the first one shows a slightly\ndifferent form.",
        "positive": "Sub-100-fs formation of dark excitons in monolayer WS$_2$: Two-dimensional semiconductors based on transition metal dichalcogenides are\npromising for electronics and optoelectronics applications owing to their\nproperties governed by strongly-bound bright and dark excitons.\nMomentum-forbidden dark excitons have recently received attention as better\nalternatives to bright excitons for long-range transport. However, accessing\nthe dynamics of dark excitons is challenging experimentally. The most direct,\nbut very complicated, experiment is transient angle-resolved photoemission\nelectron spectroscopy: sub-100-fs formation of K-$\\Lambda$-excitons in\nmonolayer WS$_2$ has been identified previously taking advantage of momentum\nresolution of detected signals [1]. Here, we use a simpler setting of transient\nphotoemission electron microscopy (with spatial resolution of 75 nm), which is\ninherently sensitive to dark K-$\\Lambda$ excitons in monolayers of transition\nmetal dichalcogenide and has exceptionally high temporal resolution of 13 fs.\nWe are able to directly observe intervalley scattering (dark-exciton formation)\nin monolayer WS$_2$ with scattering rates in the range of 14-50 fs followed by\npicosecond-scale dynamics mediated by defects."
    },
    {
        "anchor": "Wigner time delay induced by a single quantum dot: Resonant scattering of weak coherent laser pulses on a single two-level\nsystem (TLS) realized in a semiconductor quantum dot is investigated with\nrespect to a time delay between incoming and scattered light. This type of time\ndelay was predicted by Wigner in 1955 for purely coherent scattering and was\nconfirmed for an atomic system in 2013 [R. Bourgain et al., Opt. Lett. 38, 1963\n(2013)]. In the presence of electron-phonon interaction we observe deviations\nfrom Wigner's theory related to incoherent and strongly non-Markovian\nscattering processes which are hard to quantify via a detuning-independent pure\ndephasing time. We observe detuning-dependent Wigner delays of up to 530\\,ps in\nour experiments which are supported quantitatively by microscopic theory\nallowing for pure dephasing times of up to 950\\,ps.",
        "positive": "Performance engineering of semiconductor spin qubit systems: The performance of a quantum computation system is investigated, with qubits\nrepresented by magnetic impurities in coupled quantum dots filled with two\nelectrons. Magnetic impurities are electrically manipulated by electrons. The\ndominant noise source is the electron mediated indirect coupling between\nmagnetic impurities and host spin bath. As a result of the electron mediated\ncoupling, both noise properties and the time needed for elementary gate\noperations, depend on controllable system parameters, such as size and geometry\nof the quantum dot, and external electric and magnetic fields. We find that the\nmaximum number of quantum operations per coherence time for magnetic impurities\nincreases as electron spin singlet triplet energy gap decreases. The advantage\nof magnetic impurities over electrons for weak coupling and large magnetic\nfields will be illustrated."
    },
    {
        "anchor": "Multiresonances of quasi-trapped modes in metasurfaces based on\n  nanoparticles of transition metal dichalcogenides: The features of polarization control of multiple multiresonances for\nquasi-trapped modes excited by synchronization of bianisotropic dipole\nresponses in MoS$_2$ disks with a hole are considered. Using the numerical\ncalculations with analytical multipole analysis, we showed that the presence of\na strong optical anisotropy of MoS$_2$ nanoparticles provides an additional\ndegree of freedom and allows to observe several resonances of electric and\nmagnetic dipoles at once in a narrow spectral range. Based on the simulation\nresults, we obtained the frequency dependences for the dipole polarizabilities\nof the MoS$_2$ disk with a hole, which allow one to distinguish the\ncontributions of the nonlocal and bianisotropic dipole responses and possessing\nseveral features in the near infrared range. Using the polarizability spectra\nof single nanoparticles and applying the tuning strategy, the design of the\nMoS$_2$ metasurface supporting three resonances of quasi-trapped modes at once\nin a narrow spectral range was developed. One of these resonances corresponds\nto the telecom wavelength of 1550 nm. The spectrum of light reflection for\nMoS$_2$ metasurface is characterized by three narrowband dips corresponding to\nthe wavelengths of the quasi-trapped modes. It was shown that a change in the\npolarization of a wave normally incident on the metasurface to orthogonal one\nleads to a change in the type of bianisotropic response excited in each MoS$_2$\ndisk and to the excitation of three other features in the reflection spectra of\nthe metasurface at wavelengths close to the initial values.",
        "positive": "The conductance of the gated Aharonov - Bohm ring touching a quantum\n  wire: We analyse the conductance of the Aharonov-Bohm one-dimensional quantum ring\ntouching a quantum wire. It is shown that in accordance with experimental data\nthe period of the AB oscillations strongly depends on the chemical potential\nand the Rashba coupling parameter. The dependence of the conductance on the\ncarrier's energy is shown to reveal the Fano resonances."
    },
    {
        "anchor": "Spin-valley system in a gated MoS$_2$-monolayer quantum dot: The aim of presented research is to design a nanodevice based on a\ngate-defined quantum dot within a MoS$_2$ monolayer in which we confine a\nsingle electron. By applying control voltages to the device gates we modulate\nthe confinement potential and force intervalley transitions. The present Rashba\nspin-orbit coupling additionally allows for spin operations. Moreover, both\neffects enable the spin-valley SWAP. The device structure is modeled\nrealistically, taking into account feasible dot-forming potential and electric\nfield that controls the Rasha coupling. Therefore, by performing reliable\nnumerical simulations, we show how by electrically controlling the state of the\nelectron in the device, we can obtain single- and two-qubit (thus universal)\ngates in a spin-valley two-qubit system. Through simulations we investigate\npossibility of implementation of two qubits \\textit{locally}, based on single\nelectron, with an intriguing feature that two-qubit gates are easier to realize\nthan single ones.",
        "positive": "Penetration of hot electrons through a cold disordered wire: We study a penetration of an electron with high energy E<<T through strongly\ndisordered wire of length L<<a (a being the localization length). Such an\nelectron can loose, but not gain the energy, when hopping from one localized\nstate to another. We have found a distribution function for the transmission\ncoefficient t. The typical t remains exponentially small in L/a, but with the\ndecrement, reduced compared to the case of direct elastic tunnelling. The\ndistribution function has a relatively strong tail in the domain of anomalously\nhigh t; the average <t>~(a/L)^2 is controlled by rare configurations of\ndisorder, corresponding to this tail."
    },
    {
        "anchor": "Substrate effects on surface magetetism of Fe/W(110) from first\n  principles: Surface magnetic properties of the pseudomorphic Fe(110) monolayer on a\nW(110) substrate are investigated from first principles as a function of the\nsubstrate thickness (up to eight layers). Analyzing the magnetocrystalline\nanisotropy energies, we find stable (with respect to the number of substrate\nlayers) in-plane easy and hard axes of magnetization along the [1[overline 1]0]\nand [001] directions, respectively, reaching a value in good agreement with\nexperiment for thick substrates. Additionally, the changes to the magnetic spin\nmoments and the density of the Fe d states are analyzed with respect to the\nnumber of substrate layers as well as with respect to the direction of\nmagnetization. With respect to the number of W(110) substrate layers beneath\nthe Fe(110) surface, we find that the first four substrate layers have a large\ninfluence on the electronic and magnetic properties of the surface. Beyond the\nfourth layer, the substrate has only marginal influence on the surface\nproperties.",
        "positive": "Reconstruction of Tip-Surface Interactions with Multimodal\n  Intermodulation Atomic Force Microscopy: We propose a theoretical framework for reconstructing tip-surface\ninteractions using the intermodulation technique when more than one eigenmode\nis required to describe the cantilever motion. Two particular cases of bimodal\nmotion are studied numerically: one bending and one torsional mode, and two\nbending modes. We demonstrate the possibility of accurate reconstruction of a\ntwo-dimensional conservative force field for the former case, while dissipative\nforces are studied for the latter."
    },
    {
        "anchor": "Magnetic dipole absorption of light at intersubband transitions in\n  quantum wells: We consider theoretically magnetic dipole mechanism of the IR-light\nabsorption at intersubband transitions in wide-gap quantum wells (QW). In\ncontrast to the electric dipole resonance, discussed mechanism manifests in the\ninteraction with the s-polarized component of electromagnetic radiation. We\ndemonstrated that a) the frequencies of magnetic and electric dipole\nintersubband transitions in 2D layer are equal in the framework of one-particle\napproximation; b) collective plasma effects should lead to a significant\nfrequency shift between the magnetic and electric dipole resonances in typical\nQW. That is why independent measurements of the magnetic and electric dipole\nresonant frequencies could allow both the extracting the QW parameters and the\nexperimental verifying of theoretical models of collective fermion interaction.\nTaking into account relative weakness of the magnetic dipole absorption, we\npropose a waveguide scheme for its experimental observation.",
        "positive": "Spin-orbit enhancement in Si/SiGe heterostructures with oscillating Ge\n  concentration: We show that Ge concentration oscillations within the quantum well region of\na Si/SiGe heterostructure can significantly enhance the spin-orbit coupling of\nthe low-energy conduction-band valleys. Specifically, we find that for Ge\noscillation wavelengths near $\\lambda = 1.57~\\text{nm}$ with an average Ge\nconcentration of $\\bar{n}_{\\text{Ge}} = 5\\%$ in the quantum well region, a\nDresselhaus spin-orbit coupling is induced, at all physically relevant electric\nfield strengths, which is over an order of magnitude larger than what is found\nin conventional Si/SiGe heterostructures without Ge concentration oscillations.\nThis enhancement is caused by the Ge concentration oscillations producing\nwave-function satellite peaks a distance $2 \\pi/\\lambda$ away in momentum space\nfrom each valley, which then couple to the opposite valley through Dresselhaus\nspin-orbit coupling. Our results indicate that the enhanced spin-orbit coupling\ncan enable fast spin manipulation within Si quantum dots using electric dipole\nspin resonance in the absence of micromagnets. Indeed, our calculations yield a\nRabi frequency $\\Omega_{\\text{Rabi}}/B > 500~\\text{MHz/T}$ near the optimal Ge\noscillation wavelength $\\lambda = 1.57~\\text{nm}$."
    },
    {
        "anchor": "Optical properties of graphene: Reflectance and transmittance of graphene in the optical region are analyzed\nas a function of frequency, temperature, and carrier density. We show that the\noptical graphene properties are determined by the direct interband electron\ntransitions. The real part of the dynamic conductivity in doped graphene at low\ntemperatures takes the universal constant value, whereas the imaginary part is\nlogarithmically divergent at the threshold of interband transitions.",
        "positive": "Mach-Zehnder interferometry using spin- and valley-polarized quantum\n  Hall edge states in graphene: Confined to a two-dimensional plane, electrons in a strong magnetic field\ntravel along the edge in one-dimensional quantum Hall channels that are\nprotected against backscattering. These channels can be used as solid-state\nanalogues of monochromatic beams of light, providing a unique platform for\nstudying electron interference. Electron interferometry is regarded as one of\nthe most promising routes for studying fractional and non-Abelian statistics\nand quantum entanglement via two-particle interference. However, creating an\nedge-channel interferometer in which electron-electron interactions play an\nimportant role requires a clean system and long phase coherence lengths. Here\nwe realize electronic Mach-Zehnder interferometers with record visibilities of\nup to 98% using spin- and valley-polarized edge channels that co-propagate\nalong a PN junction in graphene. We find that inter-channel scattering between\nsame-spin edge channels along the physical graphene edge can be used to form\nbeamsplitters, while the absence of inter-channel scattering along gate-defined\ninterfaces can be used to form isolated interferometer arms. Surprisingly, our\ninterferometer is robust to dephasing effects at energies an order of magnitude\nlarger than observed in pioneering experiments on GaAs/AlGaAs quantum wells.\nOur results shed light on the nature of edge-channel equilibration and open up\nnew possibilities for studying exotic electron statistics and quantum\nphenomena."
    },
    {
        "anchor": "Magnetic behavior of nanoparticles in patterned thin films: The magnetic behavior of truncated conical nanoparticles in patterned thin\nfilms is investigated as a function of their size and shape. Using a scaling\ntechnique, phase diagrams giving the relative stability of characteristic\ninternal magnetic structures of the particles are obtained. The role of the\nuniaxial anisotropy in determining the magnetic properties of such systems is\ndiscussed, and a simple method for stablishing its strength is proposed.",
        "positive": "Influence of Quantum and Thermal Noise on Spin-Torque-Driven\n  Magnetization Switching: We apply a recently developed quantum theory of spin transfer torque to study\nthe effect of the quantum noise in spin transfer process on the magnetization\nswitching in spin-torque-driven devices. The quantum noise induces considerable\nfluctuation of the switching time at zero temperature. By including the thermal\nnoise, the temperature dependence of the expectation value and standard\ndeviation of the switching time are obtained in the Monte Carlo simulations,\nand the results are fitted to an effective first passage model. We expect that\nthe predictions here are observable in the single-shot measurement experiments."
    },
    {
        "anchor": "Electronic states induced by nonmagnetic defects in two-dimensional\n  topological insulators: We study in-gap electronic states induced by a nonmagnetic defect with\nshort-range potential in two-dimensional topological insulators and trace their\nevolution as the distance between the defect and the boundary changes. The\ndefect located far from the boundary is found to produce two bound states\nindependently of the sign of its potential. The states are classified as\nelectronlike and holelike. Each of these states can have two types of the\nspatial distribution of the electron density. The first-type states have a\nmaximum of the density in the center and the second-type ones have a minimum.\nWhen the defect is coupled with the boundary, the bound states are transformed\ncorrespondingly into resonances of two types and take up the form of the edge\nstates flowing around the defect. Under certain conditions, two resonances\ninterfere giving rise to the formation of a bound state embedded into the\ncontinuum spectrum of the edge states flowing around the defect. We calculate\nthe spatial distribution of the electron density in the edge states flowing\naround the defect and estimate the charge accumulated near the defect. The\ncurrent density field of the edge states flowing around the defect contains two\ncomponents one of which flows around the defect and the other circulates around\nit.",
        "positive": "Rotating electrons in quantum dots: Quantum Hall liquid in the classical\n  limit: We solve the problem of a few electrons in a two-dimensional harmonic\nconfinement using quantum mechanical exact diagonalization technique, on one\nhand, and classical mechanics, on the other hand. The quantitative agreement\nbetween the results of these two calculations suggests that, at low filling\nfactors, all the low energy excitations of quantum Hall liquid are classical\nvibrations of localized electrons. The Coriolis force plays a dominant role in\ndetermining the classical vibration frequencies."
    },
    {
        "anchor": "Periodically Gated Bilayer Graphene as an Electronic Metamaterial: We study ballistic transport in periodically gated bilayer graphene as a\ncandidate for a 2D electronic metamaterial. Our calculations use the\nequilibrium Green function formalism and take into account quantum corrections\nto charge density changes induced by a periodically modulated top gate voltage.\nOur results reveal an intriguing interference-like pattern, similar to that of\na Fabry-Perot interferometer, in the resistance map as a function of the\nvoltage $V_{BG}$ applied to the extended bottom gate and $V_{TG}$ applied to\nthe periodic top gate.",
        "positive": "Phononic thermal conductivity in silicene: the role of vacancy defects\n  and boundary scattering: We calculate the thermal conductivity of free-standing silicene using the\nphonon Boltzmann transport equation within the relaxation time approximation.\nIn this calculation, we investigate the effects of sample size and different\nscattering mechanisms such as phonon-phonon, phonon-boundary, phonon-isotope\nand phonon-vacancy defect. Moreover, the role of different phonon modes is\nexamined. We show that, in contrast to graphene, the dominant contribution to\nthe thermal conductivity of silicene originates from the in-plane acoustic\nbranches, which is about 70\\% at room temperature and this contribution becomes\nlarger by considering vacancy defects. Our results indicate that while the\nthermal conductivity of silicene is significantly suppressed by the vacancy\ndefects, the effect of isotopes on the phononic transport is small. Our\ncalculations demonstrate that by removing only one of every 400 silicon atoms,\na substantial reduction of about 58\\% in thermal conductivity is achieved.\nFurthermore, we find that the phonon-boundary scattering is important in\ndefectless and small-size silicene samples, specially at low temperatures."
    },
    {
        "anchor": "Nanogranular Thermoelectrics: We investigate thermopower and thermoelectric coefficient of nano-granular\nmaterials at large tunneling conductance between the grains, g_{T} >> 1. We\nshow that at intermediate temperatures, T >= g_{T}\\delta, where \\delta is the\nmean energy level spacing for a single grain, electron-electron interaction\nleads to an increase of the thermopower with decreasing grain size. We discuss\nour results in the light of new types of thermoelectric materials and present\nthe behavior of the figure of merit depending on system parameters.",
        "positive": "Strain-driven chiral phonons in two-dimensional hexagonal materials: Hexagonal two-dimensional materials with broken inversion symmetry (as BN or\ntransition metal dichalcodenides) are known to sustain chiral phonons with\nfinite angular momentum, adding a further useful degree of freedom to the\nextraordinary entangled (electrical, optical, magnetic and mechanical)\nproperties of these compounds. However, because of lattice symmetry\nconstraints, such chiral modes are constrained to the corners of the Brillouin\nzone, allowing little freedom for manipulating the chiral features. In this\nwork, we show how the application of uniaxial strain leads to the existence of\nnew chiral modes in the vicinity of the zone center. We also show that such\nstrain-induced chiral modes, unlike the ones pinned at the K points, can be\nefficiently manipulated by modifying the strain itself, which determines the\nposition of these modes in the Brillouin Zone. The results of the present paper\nadd a new technique for the engineering of the quantum properties of\ntwo-dimensional lattices."
    },
    {
        "anchor": "Transport signatures of Majorana bound states in superconducting hybrid\n  structures: In this minireview, we outline the recent experimental and theoretical\nprogress in the creation, characterization and manipulation of Majorana bound\nstates (MBSs) in semiconductor-superconductor (SC) hybrid structures. After an\nintroductory overview of the broader field we specifically focus on four of our\nrecent projects in this direction. We show that the emergence of Fano\nresonances in the differential conductance in a normal lead-Majorana\nnanowire-quantum dot setup can be exploited to determine if a single MBS is\ncontacted by the normal lead and the quantum dot providing an experimental test\nof the non-locality of MBSs. In the second project, the tunnel-coupling to two\nMBSs in an $s$-wave SC-Majorana nanowire Josephson junction (JJ) leads to a\nfinite contribution of the MBSs to the equilibrium Josephson current probing\ndirectly the local spin-singlet contribution of the Majorana pair. We then\nshift our focus from MBSs forming in nanowire systems to MBSs forming in\ntopological JJs. In a single sheet of buckled silicene with proximity induced\nsuperconductivity two local electric fields can be used to tune the junction\nbetween a topologically trivial and topologically non-trivial regime. In a\nCorbino geometry topological Josephson junction two MBSs harbored in Josephson\nvortices can rotate along the JJ and, in the course of this, will be exchanged\nperiodically in the phase difference of the JJ. The tunneling current in a\nmetal tip coupled to the JJ is shown to exhibit signs of the anyonic braiding\nphase of two MBSs.",
        "positive": "Valley filter in strain engineered graphene: We propose a simple, yet highly efficient and robust device for producing\nvalley polarized current in graphene. The device comprises of two distinct\ncomponents; a region of uniform uniaxial strain, adjacent to an out-of-plane\nmagnetic barrier configuration formed by patterned ferromagnetic gates. We show\nthat when the amount of strain, magnetic field strength, and Fermi level are\nproperly tuned, the output current can be made to consist of only a single\nvalley contribution. Perfect valley filtering is achievable within\nexperimentally accessible parameters."
    },
    {
        "anchor": "Tunable Adsorbate-Adsorbate Interactions on Graphene: We propose a mechanism to control the interaction between adsorbates on\ngraphene. The interaction between a pair of adsorbates---the change in\nadsorption energy of one adsorbate in the presence of another---is dominated by\nthe interaction mediated by graphene's pi-electrons and has two distinct\nregimes. Ab initio density functional, numerical tight-binding, and analytical\ncalculations are used to develop the theory. We demonstrate that the\ninteraction can be tuned in a wide range by adjusting the adsorbate-graphene\nbonding or the chemical potential.",
        "positive": "First-principles investigation of transient current of molecular devices\n  by using complex absorbing potential: Based on the non-equilibrium Green's function (NEGF) coupled with density\nfunction theory (DFT), namely, NEGF-DFT quantum transport theory, we propose an\nefficient formalism to calculate the transient current of molecular devices\nunder a step-like pulse from first principles. By combining NEGF-DFT with the\ncomplex absorbing potential (CAP), the computational complexity of our\nformalism (NEGF-DFT-CAP) is proportional to $\\emph{O}(N)$ where $N$ is the\nnumber of time steps in the time-dependent transient calculation. Compared with\nstate-of-the-art algorithm of first principles time-dependent calculation that\nscales with at least $N^2$, this order N technique drastically reduces the\ncomputational burden making it possible to tackle realistic molecular devices.\nTo ensure the accuracy of our method, we carry out the benchmark calculation\ncompared with exact NEGF-TDDFT formalism and they agree well with each other.\nAs an illustration, we investigate the transient current of molecular device\nAl-C$_3$-Al from first principles."
    },
    {
        "anchor": "Coulomb interaction effects on the Majorana states in quantum wires: The stability of the Majorana modes in the presence of a repulsive\ninteraction is studied in the standard semiconductor wire - metallic\nsuperconductor configuration. The effects of short-range Coulomb interaction,\nwhich is incorporated using a purely repulsive $\\delta$-function to model the\nstrong screening effect due to the presence of the superconductor, are\ndetermined within a Hartree-Fock approximation of the effective Bogoliubov-De\nGennes Hamiltonian that describes the low-energy physics of the wire. Through a\nnumerical diagonalization procedure we obtain interaction corrections to the\nsingle particle eigenstates and calculate the extended topological phase\ndiagram in terms of the chemical potential and the Zeeman energy. We find that,\nfor a fixed Zeeman energy, the interaction shifts the phase boundaries to a\nhigher chemical potential, whereas for a fixed chemical potential this shift\ncan occur either to lower or to higher Zeeman energies. This effects can be\ninterpreted as a renormalization of the g-factor due to the interaction. The\nminimum Zeeman energy needed to realize Majorana fermions decreases with\nincreasing the strength of the Coulomb repulsion. Furthermore, we find that in\nwires with multi-band occupancy this effect can be enhanced by increasing the\nchemical potential, i. e. by occupying higher energy bands.",
        "positive": "Split Dirac cones in HgTe/CdTe quantum wells due to symmetry-enforced\n  level anticrossing at interfaces: We describe the fine structure of Dirac states in HgTe/CdHgTe quantum wells\nof critical and close-to-critical thickness and demonstrate the formation of an\nanticrossing gap between the tips of the Dirac cones driven by interface\ninversion asymmetry. By combining symmetry analysis, atomistic calculations,\nand k-p theory with interface terms, we obtain a quantitative description of\nthe energy spectrum and extract the interface mixing coefficient. The\nzero-magnetic-field splitting of Dirac cones can be experimentally revealed in\nstudying magnetotransport phenomena, cyclotron resonance, Raman scattering, or\nTHz radiation absorption."
    },
    {
        "anchor": "Ultra-low acoustic-phonon-limited mobility and giant phonon-drag\n  thermopower in MgZnO/ZnO heterostructures: We present numerical simulations of the acoustic-phonon-limited mobility,\n$\\mu_{ac}$, and phonon-drag thermopower, $S^{g}$, in two-dimensional electron\ngases confined in MgZnO/ZnO heterostructures. The calculations are based on the\nBoltzmann equation and are made for temperatures in the range 0.3-20 K and\nsheet densities $0.5$-$30\\times 10^{15}$ m$^{-2}$. The theoretical estimations\nof $\\mu_{ac}$ are in good agreement with the experiment without any adjustable\nparameters. We find that the magnitude of $\\mu_{ac}$ is dramatically decreased\nin relation to GaAs based heterostructures. The phonon-drag thermopower,\n$S^{g}$, which according to Herring's expression is inversely proportional to\n$\\mu_{ac}$ is severely increased exceeding 200 mV/K at $T=5$ K depending on\nsheet density. The giant values of $S^{g}$ lead to a strong improvement of the\nfigure of merit $ZT$ at low temperatures. Our findings suggest that MgZnO/ZnO\nheterostructures can be candidates for good thermoelectric materials at\ncryogenic temperatures.",
        "positive": "\u03b8-Tunable Photoluminescence from Interlayer Excitons in Twisted\n  Bilayer Graphene: Using resonant 2-photon excitation of interlayer electrons in twisted bilayer\ngraphene (tBLG), we resolve photoluminescence (PL) that tunes spectrally with\nstacking angle, {\\theta}. This weak signal is 4- 5$\\times$ larger than the\nnon-resonant background and is emitted from the interlayer band anti-crossing\nregions traditionally associated with van Hove singularity resonances. However,\nour observation of resonant PL emission with delayed ~1 ps electronic\nthermalization suggests interlayer carriers may instead form bound-excitons.\nUsing both the 2-photon PL and intraband transient absorption spectra, we\nobserve bright and dark state peak-splitting associated with an interlayer\nexciton binding energy ranging from 0.5 to 0.7 eV for {\\theta} = 8$^o$ to\n17$^o$. These results support theoretical models showing interlayer excitons in\ntBLG are stabilized by a vanishing exciton-coupling strength to the metallic\ncontinuum states. This unexpected dual metal-exciton optical property of tBLG\nsuggests possible {\\theta}-tuneable control over carrier thermalization,\nextraction and emission in optical graphene-based devices."
    },
    {
        "anchor": "Flux-Dependent Level Attraction in Double-Dot Aharonov-Bohm\n  Interferometers: We study electron transport through a closed Aharonov-Bohm interferometer\ncontaining two single-level quantum dots. The quantum-dot levels are coupled to\neach other indirectly via the leads. We find that this coupling yields\nsignatures of an effective flux-dependent level attraction in the linear\nconductance. Furthermore, we predict a suppression of transport when both\nlevels are close to the Fermi level of the leads. The width of this anomaly is\nalso flux dependent. We identify different regimes in which constructive\ninterference of transmission through identical dots yields a signal that is 1,\n2, or 4 times as large as the conductance through a single dot.",
        "positive": "Transient magnetotransport through a quantum wire: We consider an ideal parabolic quantum wire in a perpendicular magnetic\nfield. A simple Gaussian shaped scattering potential well or hill is flashed\nsoftly on and off with its maximum at $t=0$, mimicking a temporary broadening\nor narrowing of the wire. By an extension of the Lippmann-Schwinger formalism\nto time-dependent scattering potentials we investigate the effects on the\ncontinuous current that is driven through the quantum wire with a vanishingly\nsmall forward bias. The Lippmann-Schwinger approach to the scattering process\nenables us to investigate the interplay between geometrical effects and effects\ncaused by the magnetic field."
    },
    {
        "anchor": "Proposals of nuclear spin quantum memory in group IV elemental and II-VI\n  semiconductors: New schemes for the nuclear spin quantum memory are proposed based on a\nsystem composed of two electrons or one electron coupled to a single nuclear\nspin in isotopically purified group IV elemental and II-VI compound\nsemiconductors. The qubit consists of the singlet state and one of the triplet\nstates of two electrons or simply of an electron spin. These systems are free\nfrom the decoherence due to the nuclear dipole-dipole interaction and are\nadvantageous for the long memory time. In the case of two electrons, the\nprotocol for the quantum state transfer between the electron spin qubit and the\nnuclear spin qubit is based on the magnetic or electric field tuning of the\nsinglet-triplet state crossing and on the hyperfine coupling supplemented with\na well-defined scheme to initialize the nuclear spin. In the case of a single\nelectron qubit, the quantum state transfer is driven by the hyperfine\ninteraction itself without the need of the nuclear spin initialization. Many\npractical systems are considered, e.g., two electrons loaded on a Si or ZnSe\nquantum dot, a single electron charged state in a Si quantum dot doped with a P\natom, a single electron charged $ ^{28}$Si quantum dot doped with an isotope\natom of $ ^{29}$Si, and a localized electron system of Si:P and ZnSe:F in the\nbulk crystal. General aspects of these systems are investigated and a\ncomparison of merits and demerits is made between the two-electron qubit and\nthe single-electron qubit.",
        "positive": "TMR transition and highly sensitive pressure sensors based on magnetic\n  tunnel junctions with black phosphorus barrier: Black phosphorus is a promising material to serve as the barrier of magnetic\ntunnel junctions (MTJs) due to the weak van der Waals interlayer interactions.\nIn particular, the special band features of black phosphorus may bring\nintriguing physical characteristics. Here, we study theoretically the effect of\nband gap tunability of black phosphorus on the MTJs with black phosphorus\nbarrier. It is found that, the tunneling magnetoresistance (TMR) may achieve a\ntransition from finite value to infinity owing to the variation of the band gap\nof black phosphorus. Combining with the latest experimental results of the\npressure-induced band gap tunability, we further investigate the pressure\neffect of TMR in the MTJs with black phosphorus barrier. The calculations show\nthat the pressure sensitivity can be quite high under appropriate parameters.\nPhysically, the high sensitivity originates from the TMR transition phenomenon.\nTo take advantage of the high pressure sensitivity, we propose and design a\ndetailed structure of highly sensitive pressure sensors based on MTJs with\nblack phosphorus barrier, whose working mechanism is basically different from\nthe convential pressure sensors. The present pressure sensors possess four\nadvantages and benifits: (1) high sensitivity, (2) well anti-interference, (3)\nhigh spatial resolution, and (4) fast response speed. Our study may advance new\nresearch area for both the MTJs and pressure sensors."
    },
    {
        "anchor": "Angle-resolved X-ray photoemission electron microscopy: Synchrotron based photoemission electron microscopy with energy filter\ncombines real space imaging with microprobe diffraction ($\\mu$-ARPES), giving\naccess to the local electronic structure of laterally inhomogeneous materials.\nWe present here an overview of the capabilities of this technique, illustrating\nselected applications of angle resolved photoemission electron microscopy and\nrelated microprobe methods. In addition, we report the demonstration of a\ndarkfield XPEEM (df-XPEEM) imaging method for real space mapping of the\nelectronic structure away from $\\Gamma$ at a lateral resolution of few tens of\nnm. The application of df-XPEEM to the (1$\\times$12)-O/W(110) model oxide\nstructure shows the high sensitivity of this technique to the local electronic\nstructure, allowing to image domains with inequivalent adsorption site\nsymmetry. Perspectives of angle resolved PEEM are discussed.",
        "positive": "Quantum Information is Physical: We discuss a few current developments in the use of quantum mechanically\ncoherent systems for information processing. In each of these developments,\nRolf Landauer has played a crucial role in nudging us and other workers in the\nfield into asking the right questions, some of which we have been lucky enough\nto answer. A general overview of the key ideas of quantum error correction is\ngiven. We discuss how quantum entanglement is the key to protecting quantum\nstates from decoherence in a manner which, in a theoretical sense, is as\neffective as the protection of digital data from bit noise. We also discuss\nfive general criteria which must be satisfied to implement a quantum computer\nin the laboratory, and we illustrate the application of these criteria by\ndiscussing our ideas for creating a quantum computer out of the spin states of\ncoupled quantum dots."
    },
    {
        "anchor": "Uniqueness of Landau levels and their analogs with higher Chern numbers: Lowest Landau level wavefunctions are eigenstates of the Hamiltonian of a\ncharged particle in two dimensions under a uniform magnetic field. They are\nknown to be holomorphic both in real and momentum spaces, and also exhibit\nuniform, translationally invariant, geometrical properties in momentum space.\nIn this paper, using the Stone-von Neumann theorem, we show that lowest Landau\nlevel wavefunctions are indeed the only possible states with unit Chern number\nsatisfying these conditions. We also prove the uniqueness of their direct\nanalogs with higher Chern numbers and provide their expressions.",
        "positive": "Zero temperature conductance of parallel T-shape double quantum dots: We analyze the zero temperature conductance of a parallel T-shaped double\nquantum dot system. We present an analytical expression for the conductance of\nthe system in terms of the total number of electrons in both quantum dots. Our\nresults confirm that the system's conductance is strongly influenced by the dot\nwhich is not directly connected to the leads. We discuss our results in\nconnection with similar results reported in the literature."
    },
    {
        "anchor": "Simulating STM transport in alkanes from first principles: Simulations of scanning tunneling microscopy measurements for molecules on\nsurfaces are traditionally based on a perturbative approach, most typically\nemploying the Tersoff-Hamann method. This assumes that the STM tip is far from\nthe sample so that the two do not interact with each other. However, when the\ntip gets close to the molecule to perform measurements, the electrostatic\ninterplay between the tip and substrate may generate non-trivial potential\ndistribution, charge transfer and forces, all of which may alter the electronic\nand physical structure of the molecule. These effects are investigated with the\nab initio quantum transport code SMEAGOL, combining non-equilibrium Green's\nfunctions formalism with density functional theory. In particular, we\ninvestigate alkanethiol molecules terminated with either CH3 or CF3 end-groups\non gold surfaces, for which recent experimental data are available. We discuss\nthe effects connected to the interaction between the STM tip and the molecule,\nas well as the asymmetric charge transfer between the molecule and the\nelectrodes.",
        "positive": "Dynamical decoupling of interacting dipolar spin ensembles: We demonstrate that CPMG and XYXY decoupling sequences with non-ideal $\\pi$\npulses can reduce dipolar interactions between spins of the same species in\nsolids. Our simulations of pulsed electron spin resonance (ESR) experiments\nshow that $\\pi$ rotations with small ($<$~10\\%) imperfections refocus\ninstantaneous diffusion. Here, the intractable N-body problem of interacting\ndipoles is approximated by the average evolution of a single spin in a changing\nmean field. These calculations agree well with experiments and do not require\npowerful hardware. Our results add to past attempts to explain similar\nphenomena in solid state nuclear magnetic resonance (NMR). Although the\nfundamental physics of NMR are similar to ESR, the larger linewidths in ESR and\nstronger dipolar interactions between electron spins compared to nuclear spins\npreclude drawing conclusions from NMR studies alone. For bulk spins, we also\nfind that using XYXY results in less inflation of the deduced echo decay times\nas compared to decays obtained with CPMG."
    },
    {
        "anchor": "Skyrmions in Magnetic Multilayers: Symmetry breaking together with strong spin-orbit interaction give rise to\nmany exciting phenomena within condensed matter physics. A recent example is\nthe existence of chiral spin textures, which are observed in magnetic systems\nlacking inversion symmetry. These chiral spin textures, including domain walls\nand magnetic skyrmions, are both fundamentally interesting and technologically\npromising. For example, they can be driven very efficiently by electrical\ncurrents, and exhibit many new physical properties determined by their\nreal-space topological characteristics. Depending on the details of the\ncompeting interactions, these spin textures exist in different parameter\nspaces. However, the governing mechanism underlying their physical behaviors\nremain essentially the same. In this review article, the fundamental\ntopological physics underlying these chiral spin textures, the key factors for\nmaterials optimization, and current developments and future challenges will be\ndiscussed. In the end, a few promising directions that will advance the\ndevelopment of skyrmion based spintronics will be highlighted.",
        "positive": "Variational Monte-Carlo calculation of the nematic state of the\n  two-dimensional electron gas in a magnetic field: We use a Jastrow-Slater wave function with an elliptical Fermi sea to\ndescribe the nematic state of the two-dimensional electron gas in a magnetic\nfield and the Monte Carlo method to calculate a variational energy upper bound.\nThese energy upper bounds are compared with other upper bounds describing\nstripe-ordered ground states which are obtained from optimized Hartree-Fock\ncalculations and with those which correspond to an isotropic ground state. Our\nfindings support the conclusions drawn in our previous study where the\nFermi-hypernetted chain approximation was used instead of the Monte Carlo\nmethod. Namely, the nematic state becomes energetically favorable relative to\nthe stripe-ordered Wigner crystal phase for the second excited Landau level and\nbelow a critical value of the layer ``thickness'' parameter which is very close\nto its value in the actual materials."
    },
    {
        "anchor": "Imaging Electron Interferometer: An imaging interferometer was created in a two-dimensional electron gas by\nreflecting electron waves emitted from a quantum point contact (QPC) with a\ncircular mirror. Images of electron flow obtained with a scanning probe\nmicroscope at liquid He temperatures show interference fringes when the mirror\nis energized. A quantum phase shifter was created by moving the mirror via its\ngate voltage, and an interferometric spectrometer can be formed by sweeping the\ntip over many wavelengths. Experiments and theory demonstrate that the\ninterference signal is robust against thermal averaging.",
        "positive": "N-dimensional electron in a spherical potential: the large-N limit: We show that the energy levels predicted by a 1/N-expansion method for an\nN-dimensional Hydrogen atom in a spherical potential are always lower than the\nexact energy levels but monotonically converge towards their exact eigenstates\nfor higher ordered corrections. The technique allows a systematic approach for\nquantum many body problems in a confined potential and explains the remarkable\nagreement of such approximate theories when compared to the exact numerical\nspectrum."
    },
    {
        "anchor": "Type-III Weyl Semimetals: (TaSe4)2I: Weyl semimetals have been classified into type-I and type-II with respect to\nthe geometry of their Fermi surfaces at the Weyl points. Here, we propose a new\nclass of Weyl semimetal, whose unique Fermi surface contains two electron or\ntwo hole pockets touching at a multi-Weyl point, dubbed as type-III Weyl\nsemimetal. Based on first-principles calculations, we first show that\nquasi-one-dimensional compound (TaSe4)2I is a type-III Weyl semimetal with\nlarger chiral charges. (TaSe4)2I can support four-fold helicoidal surface\nstates with remarkably long Fermi arcs on the (001) surface. Angle-resolved\nphotoemission spectroscopy measurements are in agreement with the gapless\nnature of (TaSe4)2I at room temperature and reveal its characteristic\ndispersion. In addition, our calculations show that external strain could\ninduce topological phase transitions in (TaSe4)2I among the type-III, type-II,\nand type-I Weyl semimetals, accompanied with the Lifshitz transitions of the\nFermi surfaces. Therefore, our work first experimentally indicates (TaSe4)2I as\na type-III Weyl semimetal and provides a promising platform to further\ninvestigate the novel physics of type-III Weyl fermions.",
        "positive": "Ultrafast optical signature of quantum superpositions in a nanostructure: We propose an unambiguous signature for detecting quantum superposition\nstates in a nanostructure, based on current ultrafast spectroscopy techniques.\nThe reliable generation of such superposition states via Hadamard-like quantum\ngates is crucial for implementing solid-state based quantum information\nschemes. The signature originates from a remarkably strong photon antibunching\neffect which is enhanced by non-Markovian dynamics."
    },
    {
        "anchor": "Tunneling blockade and single-photon emission in GaAs double quantum\n  wells: We report on the selective excitation of single impurity-bound exciton states\nin a GaAs double quantum well (DQW). The structure consists of two quantum\nwells (QWs) coupled by a thin tunnel barrier. The DQW is subject to a\ntransverse electric field to create spatially indirect inter-QW excitons with\nelectrons and holes located in different QWs. We show that the presence of\nintra-QW charged excitons (trions) blocks carrier tunneling across the barrier\nto form indirect excitons, thus opening a gap in their emission spectrum. This\nbehavior is attributed to the low binding energy of the trions. Within the\ntunneling blockade regime, emission becomes dominated by processes involving\nexcitons bound to single shallow impurities, which behave as two-level centers\nactivated by resonant tunneling. The quantum nature of the emission is\nconfirmed by the anti-bunched photon emission statistics. The narrow\ndistribution of emission energies ($\\sim 10$~meV) and the electrical connection\nto the QWs make these single-exciton centers interesting candidates for\napplications in single-photon sources.",
        "positive": "Incompressible Liquid, Stripes and Bubbles in rapidly rotating Bose\n  atoms at $\u03bd=1$: We numerically study the system of rapidly rotating Bose atoms at the filling\nfactor (ratio of particle number to vortex number) $\\nu=1$ with the dipolar\ninteraction. A moderate dipolar interaction stabilizes the incompressible\nquantum liquid at $\\nu=1$. Further addition induces a collapse of it. The state\nafter the collapse is a compressible state which has phases with stripes and\nbubbles.\n  There are two types of bubbles with a different array. We also investigate\nmodels constructed from truncated interactions and the models with the\nthree-body contact interaction. They also have phases with stripes and bubbles."
    },
    {
        "anchor": "Continuous measurements enhanced self-trapping of degenerate ultra-cold\n  atoms: Nonlinear Quantum Zeno Effect: In the present paper we investigate the influence of measurements on the\nquantum dynamics of degenerate Bose atoms gases in a symmetric double-well. We\nshow that continuous measurements enhance asymmetry on the density distribution\nof the atoms and broaden the parameter regime for self-trapping. We term this\nphenomenon as nonlinear quantum Zeno effect in analog to the celebrated Zeno\neffect in a linear quantum system. Under discontinuous measurements, the\nself-trapping due to the atomic interaction in the degenerate bosons is shown\nto be destroyed completely. Underlying physics is revealed and possible\nexperimental realization is discussed.",
        "positive": "Excitonic Magneto-Optical Kerr Effect in 2D Transition Metal\n  Dichalcogenides Induced by Spin Proximity: In this paper we develop the excitonic theory of Kerr rotation angle in a\ntwo-dimensional (2D) transition metal dichalcogenide at zero magnetic field.\nThe finite Kerr angle is induced by the interplay between spin-orbit splitting\nand proximity exchange coupling due to the presence of a ferromagnet. We\ncompare the excitonic effect with the single particle theory approach. We show\nthat the excitonic properties of the 2D material lead to a dramatic change in\nthe frequency dependence of the optical response function. We also find that\nthe excitonic corrections enhance the optical response by a factor of two in\nthe case of MoS2 in proximity to a Cobalt thin film."
    },
    {
        "anchor": "Mechanism of half-frequency electric dipole spin resonance in double\n  quantum dots: Effect of nonlinear charge dynamics inside the singlet manifold: Electron dynamics in quantum dots manifests itself in spin-flip spectra\nthrough electric dipole spin resonance (EDSR). Near a neutrality point\nseparating two different singlet charged states of a double quantum dot, charge\ndynamics inside a $2\\times2$ singlet manifold can be described by a\n1/2-pseudospin. In this region, charge dynamics is highly nonlinear and\nstrongly influenced by flopping its soft pseudospin mode. As a result, the\nresponses to external driving include first and second harmonics of the driving\nfrequency and their Raman satellites shifted by the pseudospin frequency. In\nEDSR spectra of a spin-orbit couplet doublet dot, they manifest themselves as\ncharge satellites of spin-flip transitions. The theory describes gross features\nof the anomalous half-frequency EDSR in spin blockade spectra [Laird et al.,\nSemicond. Sci. Techol. {\\bf 24}, 064004 (2009)].",
        "positive": "Temperature dependent electrical resistivity of a single strand of\n  ferromagnetic single crystalline nanowire: We have measured the electrical resistivity of a single strand of a\nferromagnetic Ni nanowire of diameter 55 nm using a 4-probe method in the\ntemperature range 3 K-300 K. The wire used is chemically pure and is a high\nquality oriented single crystalline sample in which the temperature independent\nresidual resistivity is determined predominantly by surface scattering. Precise\nevaluation of the temperature dependent resistivity ($\\rho$) allowed us to\nidentify quantitatively the electron-phonon contribution (characterized by a\nDebye temperature $\\theta_R$) as well as the spin-wave contribution which is\nsignificantly suppressed upon size reduction."
    },
    {
        "anchor": "Stability of magnetic nanowires against spin-polarized current: Stability of ground magnetization state of a thin magnetic nanowire against\nlongitudinal spin-polarized current is studied theoretically with dipole-dipole\ninteraction taken into account. The critical current, minimum current at which\nthe instability of the ground state develops, is determined. Dependence of the\ncritical current on size and form of the transversal wire cross-section is\nclarified. Theoretical predictions are confirmed by numerical micromagnetic\nsimulations.",
        "positive": "Spin polarization induced by an electric field in the presence of weak\n  localization effects: We evaluate the spin polarization (Edelstein or inverse spin galvanic effect)\nand the spin Hall current induced by an applied electric field by including the\nweak localization corrections for a two-dimensional electron gas. We show that\nthe weak localization effects yield logarithmic corrections to both the spin\npolarization conductivity relating the spin polarization and the electric field\nand to the spin Hall angle relating the spin and charge currents. The\nrenormalization of both the spin polarization conductivity and the spin Hall\nangle combine to produce a zero correction to the total spin Hall conductivity\nas required by an exact identity. Suggestions for the experimental observation\nof the effect are given."
    },
    {
        "anchor": "Antiparallel spin polarization and spin current induced by thermal\n  current and locally-broken inversion symmetry in a double-quantum-well\n  structure: Generating a nonequilibrium spin polarization with a driving force has been\nfirst realized by the electric current in a system with broken inversion\nsymmetry and extended to that induced by the thermal current and that appearing\nin an inversion-symmetric system with locally-broken inversion symmetry. This\npaper theoretically explores the spin polarization generated by the thermal\ncurrent and the locally-broken inversion symmetry in a symmetric\ndouble-quantum-well structure (DQWS). This thermally-induced spin polarization\n(TISP) appears in the antiparallel configuration with the TISP of two wells in\nopposite directions. The calculation using the Boltzmann equation in the\nrelaxation-time approximation under the condition of zero charge current shows\nthat the local TISP exhibits the maximum at a finite Rashba spin-orbit\ninteraction when the electron density is fixed. This is because the local TISP\nin the DQWS is enhanced at the chemical potential near the bottom of the\nfirst-excited subband. This enhancement also occurs in a single quantum well\nwith globally-broken inversion symmetry. Another finding is that the maximum of\nthe local TISP appears at a nonzero interwell coupling. The spin current by the\ndiffusion of the local TISP into an adjacent electrode is also calculated.",
        "positive": "A single-atom electron spin qubit in silicon: A single atom is the prototypical quantum system, and a natural candidate for\na quantum bit - the elementary unit of a quantum computer. Atoms have been\nsuccessfully used to store and process quantum information in electromagnetic\ntraps, as well as in diamond through the use of the NV-center point defect.\nSolid state electrical devices possess great potential to scale up such\ndemonstrations from few-qubit control to larger scale quantum processors. In\nthis direction, coherent control of spin qubits has been achieved in\nlithographically-defined double quantum dots in both GaAs and Si. However, it\nis a formidable challenge to combine the electrical measurement capabilities of\nengineered nanostructures with the benefits inherent to atomic spin qubits.\nHere we demonstrate the coherent manipulation of an individual electron spin\nqubit bound to a phosphorus donor atom in natural silicon, measured\nelectrically via single-shot readout. We use electron spin resonance to drive\nRabi oscillations, while a Hahn echo pulse sequence reveals a spin coherence\ntime (T2) exceeding 200 \\mu s. This figure is expected to become even longer in\nisotopically enriched 28Si samples. Together with the use of a device\narchitecture that is compatible with modern integrated circuit technology,\nthese results indicate that the electron spin of a single phosphorus atom in\nsilicon is an excellent platform on which to build a scalable quantum computer."
    },
    {
        "anchor": "Observation of Quantum Hall Valley Skyrmions: We report measurements of the interaction-induced quantum Hall effect in a\nspin-polarized AlAs two-dimensional electron system where the electrons occupy\ntwo in-plane conduction band valleys. Via the application of in-plane strain,\nwe tune the energies of these valleys and measure the energy gap of the quantum\nHall state at filling factor $\\nu$ = 1. The gap has a finite value even at zero\nstrain and, with strain, rises much faster than expected from a single-particle\npicture, suggesting that the lowest energy charged excitations at $\\nu=1$ are\n\"valley Skyrmions\".",
        "positive": "Fifteen years of microcavity polaritons: We present an overview of the advances in the physics of polaritons in\nsemiconductor microcavities, starting from their first discovery in 1992. After\nsummarizing the research during the early years, when the basic optical\nproperties were investigated, we describe the important results related to the\nphenomenon of parametric polariton scattering, highlighting its link to\nnon-classical polariton physics. We conclude with a perspective view of the\nfuture research in the domain, focusing on the exciting developments in the\ndirection of polariton quantum collective phenomena and quantum nanodevices"
    },
    {
        "anchor": "Flux Qubits with Long Coherence Times for Hybrid Quantum Circuits: We present measurements of superconducting flux qubits embedded in a three\ndimensional copper cavity. The qubits are fabricated on a sapphire substrate\nand are measured by coupling them inductively to an on-chip superconducting\nresonator located in the middle of the cavity. At their flux-insensitive point,\nall measured qubits reach an intrinsic energy relaxation time in the 6-20\nmicroseconds range and a pure dephasing time comprised between 3 and 10\nmicroseconds. This significant improvement over previous works opens the way to\nthe coherent coupling of a flux-qubit to individual spins.",
        "positive": "On the theory of the Schroedinger equation with the full set of\n  relativistic corrections: All relativistic corrections to the Scr{\\\"o}dinger equation which determine\nthe interlink between spin and orbit of moving particles, are directly\ncalculated from the Dirac equation using the spin invariant operators. It is\nshown that among the second order corrections there are not only the well-known\nDarwin and Thomas terms, but also the new ones. Only with the account of the\nlatter corrections the energies found with the obtained spin-orbit interaction\noperator, coincide with the energies of the Dirac equation exact solution. The\nproblem of electron spectrum in the quantum well type structures is studied in\ndetails and the physical reasons for the appearance of spin-orbit interaction\noperators in the Dresselhaus or Rashba form, are analyzed."
    },
    {
        "anchor": "Ultrafast electronic read-out of diamond NV centers coupled to graphene: Nonradiative transfer processes are often regarded as loss channels for an\noptical emitter1, since they are inherently difficult to be experimentally\naccessed. Recently, it has been shown that emitters, such as fluorophores and\nnitrogen vacancy centers in diamond, can exhibit a strong nonradiative energy\ntransfer to graphene. So far, the energy of the transferred electronic\nexcitations has been considered to be lost within the electron bath of the\ngraphene. Here, we demonstrate that the trans-ferred excitations can be\nread-out by detecting corresponding currents with picosecond time resolution.\nWe electrically detect the spin of nitrogen vacancy centers in diamond\nelectronically and con-trol the nonradiative transfer to graphene by electron\nspin resonance. Our results open the avenue for incorporating nitrogen vacancy\ncenters as spin qubits into ultrafast electronic circuits and for harvesting\nnon-radiative transfer processes electronically.",
        "positive": "The renormalization group for interacting fermions: from Fermi liquids\n  to quantum dots: The renormalization group approach as developed by the author for Fermi\nliquids is applied to clean Fermi liquids and ballistic quantum dots. In the\nformer case Landau theory is shown to be a fixed point and in the latter the\nUniversal Hamiltonian is shown to be a fixed point for weak coupling. The\nstrong coupling phase is analyzed using large N and Random Matrix methods."
    },
    {
        "anchor": "Electronic and Magnetic Properties of Graphite Quantum Dots: We study the electronic and magnetic properties of multilayer quantum dots\n(MQDs) of graphite in the nearest-neighbor approximation of tight-binding\nmodel. We calculate the electronic density of states and orbital susceptibility\nof the system as function of the Fermi level location. We demonstrate that\nproperties of MQD depend strongly on the shape of the system, on the parity of\nthe layer number and on the form of the cluster edge. The special emphasis is\ngiven to reveal the new properties with respect to the monolayer quantum dots\nof graphene. The most interesting results are obtained for the triangular MQD\nwith zig-zag edge at near-zero energies. The asymmetrically smeared multi-peak\nfeature is observed at Dirac point within the size-quantized energy gap region,\nwhere monolayer graphene flakes demonstrate the highly-degenerate zero-energy\nstate. This feature, provided by the edge-localized electronic states results\nin the splash-wavelet behavior in diamagnetic orbital susceptibility as\nfunction of energy.",
        "positive": "Theoretical evaluation of [V$^{IV}$(\u03b1-C$_3$S$_5$)]${^2-}$ as\n  nuclear-spin sensitive single-molecule spin transistor: In a straightforward application of molecular nanospintronics to quantum\ncomputing, single-molecule spin transistors can be used to measure and control\nnuclear spin qubits. A jump in the conductance occurs when the electronic spin\ninverts its polarization, and this happens at a so-called anticrossing between\nenergy levels, which in turn only takes place at a specific magnetic field\ndetermined by the nuclear spin state. So far, this procedure has only been\nimplemented for the terbium(III) bis(phthalocyaninato) complex. Here we explore\ntheoretically whether a similar behavior is expected for a highly stable\nmolecular spin qubit, the vanadium tris-dithiolate complex\n[V$^{IV}$({\\alpha}-C$_3$S$_5$)]${^2-}$. We consider such molecule sandwiched\ninto a two-terminal device and determine the spin-dependent conductance. We\nverify that the transport channel at minimal bias voltage does not overlap with\nthe occupied spin orbitals, indicating that the spin states may survive in the\nconduction regime. We estimate some physical parameters to guide the\nexperiments, and verify the robustness of the theoretical methodology by\napplying it to two chemically related vanadium complexes."
    },
    {
        "anchor": "Photoluminescence studies of Zeeman effect in type-II InSb/InAs\n  nanostructures: Electron spin polarization up to 100% has been observed in type-II narrow-gap\nheterostructures with ultrathin InSb insertions in an InAs matrix via\ninvestigation of circularly polarized photoluminescence in an external magnetic\nfield applied in Faraday geometry. The polarization degree decreases\ndrastically, changes its sign, and saturates finally at the value of 10% in the\nlimit of either high temperature or strong excitation. The observed effect is\nexplained in terms of strong Zeeman splitting of the electron conduction band\nin the InAs matrix and a heavy-hole state confined in the InSb insertion, due\nto a large intrinsic g-factor of both types of carriers. The hole ground state\nin a monolayer scale InSb/InAs quantum well, calculated using a tight-binding\napproach, fits well the observed emission wavelength. Temperature dependence of\nthe emission polarization degree is in good agreement with its theoretical\nestimation performed in the framework of a proposed phenomenological model.",
        "positive": "2D Rashba system in AC magnetic field: The response of an electron system to a DC measurement electric field has\nbeen investigated in the case when the system is driven out of the equilibrium\nby the magnetic ultra-high frequency field that leads to combined transitions.\nThe discussed model includes contributions from Landau quantization and from\nmicrowave irradiation. Impurity centers are considered as sources of\nscattering. It has been shown that the perturbation of the electron system by\nthe ultra-high frequency magnetic field leads to oscillations of the diagonal\ncomponents of the conductivity tensor."
    },
    {
        "anchor": "Identifying Majorana bound states by tunneling shot-noise tomography: Majorana fermions are promising building blocks of forthcoming technology in\nquantum computing. However, their non-ambiguous identification has remained a\ndifficult issue because of the concomitant competition with other topologically\ntrivial fermionic states, which poison their detection in most spectroscopic\nprobes. By employing numerical and analytical methods, here we show that the\nFano factor tomography is a key distinctive feature of a Majorana bound state,\ndisplaying a spatially constant Poissonian value equal to one. In contrast, the\nFano factor of other trivial fermionic states, like the Yu-Shiba-Rusinov or\nAndreev ones, is strongly spatially dependent and exceeds one as a direct\nconsequence of the local particle-hole symmetry breaking.",
        "positive": "Excitation of relaxation oscillations in a semiconductor superlattice by\n  incident waves: efficient terahertz harmonics generation: Generation of terahertz harmonics by frequency multiplication with a\nsemiconductor superlattice due to an excitation of relaxation oscillations by\nincident waves is investigated theoretically. It is shown that the relaxation\noscillations excitation becomes feasible if the superlattice dc resistance is\nlow enough in comparison with a characteristic radiation impedance of the\nexternal waveguide system. The power of the generated harmonics as a function\nof the incident wave power demonstrates a threshold-like behavior at a specific\ninput power level dependent on the superlattice peak current. We demonstrate\nthat for typical superlattice parameters the roll-of frequency of the generated\nharmonics is mostly specified by the plasma frequency of electrons in a\nsuperlattice miniband. We argue that an increase of the superlattice miniband\nwidths could essentially enhance both the efficiency and the spectral range of\nthe generated terahertz harmonics."
    },
    {
        "anchor": "An algebraic approach to the study of weakly excited states for a\n  condensate in a ring geometry: We determine the low-energy spectrum and the eigenstates for a two-bosonic\nmode nonlinear model by applying the In\\\"{o}n\\\"{u}-Wigner contraction method to\nthe Hamiltonian algebra. This model is known to well represent a Bose-Einstein\ncondensate rotating in a thin torus endowed with two angular-momentum modes as\nwell as a condensate in a double-well potential characterized by two space\nmodes. We consider such a model in the presence of both an attractive and a\nrepulsive boson interaction and investigate regimes corresponding to different\nvalues of the inter-mode tunneling parameter. We show that the results ensuing\nfrom our approach are in many cases extremely satisfactory. To this end we\ncompare our results with the ground state obtained both numerically and within\na standard semiclassical approximation based on su(2) coherent states.",
        "positive": "Full Counting Statistics of Electron Tunneling through Coherently\n  Coupled Quantum Dots: Exchange Interaction Effect on Shot Noise: We investigate the zero-frequency shot noise of electronic tunneling through\na single quantum dot (SQD) and coherently coupled quantum dots (CQD) taking\ninto account the Coulomb interaction. Within Hartree-Fock approximation, the\nanalytical expressions of current and zero-frequency shot noise are\nself-consistently derived in the framework of full counting statistics for the\nboth systems. We demonstrate that the correction term of zero-frequency shot\nnoise induced by the intradot Coulomb interaction is almost negligible compared\nto the noninteracting shot noise in a SQD, while in a CQD the interplay of the\ninterdot coherence fluctuations and strong interdot Coulomb interaction can\ninduce a super-Poissonian noise even in the symmetric case."
    },
    {
        "anchor": "Semiconductor quantum plasmons for high frequency thermal emission: Plasmons in heavily doped semiconductor layers are optically active\nexcitations with sharp resonances in the 5-15 um wavelength region set by the\ndoping level and the effective mass. Here we demonstrate that volume plasmons\ncan form in doped layers of widths of hundreds of nanometers, without the need\nof potential barrier for electronic confinement. Their strong interaction with\nlight makes them perfect absorber and therefore suitable for incandescent\nemission. Moreover, by injecting microwave current in the doped layer, we can\nmodulate the temperature of the electron gas. We have fabricated devices for\nhigh frequency thermal emission and measured incandescent emission up to 50MHz,\nlimited by the cutoff of our detector. The frequency dependent thermal emission\nis very well reproduced by our theoretical model that let us envision a\nfrequency cutoff in the tens of GHz.",
        "positive": "Nuclear spin dynamics and noise in anisotropic large box model: We consider the central spin model in the box approximation taking into\naccount external magnetic field and anisotropy of the hyperfine interaction.\nFrom the exact Hamiltonian diagonalization we obtain analytical expressions for\nthe nuclear spin dynamics in the limit of many nuclear spins. We predict the\nnuclear spin precession in zero magnetic field for the case of anisotropic\ninteraction between electron and nuclear spins. We calculate and describe the\nnuclear spin noise spectra in the thermodynamic equilibrium. The obtained\nresults can be used for the analysis of the nuclear spin induced current\nfluctuations in organic semiconductors."
    },
    {
        "anchor": "Strain engineering in semiconducting two-dimensional crystals: One of the fascinating properties of the new families of two-dimensional\ncrystals is their high stretchability and the possibility to use external\nstrain to manipulate, in a controlled manner, their optical and electronic\nproperties. Strain engineering, understood as the field that study how the\nphysical properties of materials can be tuned by controlling the elastic strain\nfields applied to it, has a perfect platform for its implementation in the\natomically thin semiconducting materials. The object of this review is to give\nan overview of the recent progress to control the optical and electronics\nproperties of 2D crystals, by means of strain engineering. We will concentrate\non semiconducting layered materials, with especial emphasis in transition metal\ndichalcogenides (MoS$_2$, WS$_2$, MoSe$_2$ and WSe$_2$). The effect of strain\nin other atomically thin materials like black phosphorus, silicene, etc., is\nalso considered. The benefits of strain engineering in 2D crystals for\napplications in nanoelectronics and optoelectronics will be revised, and the\nopen problems in the field will be discussed.",
        "positive": "Exciton-photon interactions in semiconductor nanocrystals: {radiative\n  transitions, non-radiative processes,} and environment effects: In this review we discuss several fundamental processes taking place in\nsemiconductor nanocrystals (quantum dots, QDs) when their electron subsystem\ninteracts with electromagnetic (EM) radiation. The physical phenomena of light\nemission and EM energy transfer from a QD exciton to other electronic systems\nsuch as neighbouring nanocrystals and polarisable 3D (semi-infinite dielectric\nor metal) and 2D (graphene) materials are considered. The cases of direct\n(II-VI) and indirect (silicon) band gap semiconductors are compared. We also\ncover the relevant non-radiative mechanisms such as the Auger process, electron\ncapture on dangling bonds and interaction with phonons. The emphasis is on\nexplaining the underlying physics and illustrating it with calculated and\nexperimental results in a comprehensive, tutorial manner."
    },
    {
        "anchor": "Spin relaxation in a zinc-blende (110) symmetric quantum well with\n  delta-doping: The spin relaxation of a two-dimensional electron system (2DES) formed in a\nsymmetric quantum well is studied theoretically when the quantum well is\nparallel to the (110) plane of the zinc-blende structure, the spin polarization\nis perpendicular to the well, and electrons occupy only the ground subband. The\nspin relaxation rate is calculated as a function of the distribution of donor\nimpurities which are placed in the well layer. Considered processes of the spin\nrelaxation are (1) intrasubband process by impurity-potential-induced\nspin-orbit interaction (SOI), which is the Elliott-Yafet mechanism in the 2DES,\nand (2) virtual intersubband processes consisting of a spin flip by (2a)\nwell-potential-induced SOI or (2b) the Dresselhaus SOI, and a scattering from\nan impurity. It is shown that all of the above processes disappear, when all\nimpurities are located on the center plane of the well. Even if impurities are\ndistributed over three (110) atomic layers, the spin relaxation rate is two\norders of magnitude lower than that for the uniform distribution over the well\nwidth of 7.5\\ nm. In GaAs/AlGaAs type-I quantum wells the processes (1) and\n(2a) interfere constructively, being dominant over (2b) for the well width of\n$\\sim$10\\ nm, while in some type-II quantum wells they can interfere\ndestructively.",
        "positive": "Impact of the Ga flux incidence angle on the growth kinetics of\n  self-assisted GaAs nanowires on Si(111): In this work we show that the incidence angle of group-III elements fluxes\nplays a significant role on the diffusion-controlled growth of III-V nanowires\n(NWs) by molecular beam epitaxy (MBE). We present a thorough experimental study\non the self-assisted growth of GaAs NWs by using a MBE reactor equipped with\ntwo Ga cells located at different incidence angles with respect to the surface\nnormal of the substrate, so as to ascertain the impact of such a parameter on\nthe NW growth kinetics. The as-obtained results show a dramatic influence of\nthe Ga flux incidence angle on the NW length and diameter, as well as on the\nshape and size of the Ga droplets acting as catalysts. In order to interpret\nthe results we developed a semi-empirical analytic model inspired by those\nalready developed for MBE-grown Au-catalyzed GaAs NWs. Numerical simulations\nperformed with the model allow to reproduce thoroughly the experimental results\n(in terms of NW length and diameter and of droplet size and wetting angle),\nputting in evidence that under formally the same experimental conditions the\nincidence angle of the Ga flux is a key parameter which can drastically affect\nthe growth kinetics of the NWs grown by MBE."
    },
    {
        "anchor": "Transport of interacting electrons in arrays of quantum dots and\n  diffusive wires: We develop a detailed theoretical investigation of the effect of Coulomb\ninteraction on electron transport in arrays of chaotic quantum dots and\ndiffusive metallic wires. Employing the real time path integral technique we\nformulate a new Langevin-type of approach which exploits a direct relation\nbetween shot noise and interaction effects in mesoscopic conductors. With the\naid of this approach we establish a general expression for the Fano factor of\n1D quantum dot arrays and derive a complete formula for the interaction\ncorrection to the current which embraces all perturbative results previously\nobtained for various quasi-0D and quasi-1D disordered conductors and extends\nthese results to yet unexplored regimes.",
        "positive": "A quantum critical point in the transverse field of Mn12 system: Using exact diagonalization method,we studied the ground state of the\nanisotropic molecular magnets and find a critical point in the transverse\nfield,which may divide the quantum tunneling region into two different parts.\nPossible ways to observe and take advantage of this point by varying the\ntransverse field are suggested."
    },
    {
        "anchor": "Bose-Einstein condensation of quasiparticles in graphene: The collective properties of different quasiparticles in various graphene\nbased structures in high magnetic field have been studied. We predict\nBose-Einstein condensation (BEC) and superfluidity of 2D spatially indirect\nmagnetoexcitons in two-layer graphene. The superfluid density and the\ntemperature of the Kosterlitz-Thouless phase transition are shown to be\nincreasing functions of the excitonic density but decreasing functions of\nmagnetic field and the interlayer separation. The instability of the ground\nstate of the interacting 2D indirect magnetoexcitons in a slab of superlattice\nwith alternating electron and hole graphene layers (GLs) is established. The\nstable system of indirect 2D magnetobiexcitons, consisting of pair of indirect\nexcitons with opposite dipole moments, is considered in graphene superlattice.\nThe superfluid density and the temperature of the Kosterlitz-Thouless phase\ntransition for magnetobiexcitons in graphene superlattice are obtained.\nBesides, the BEC of excitonic polaritons in GL embedded in a semiconductor\nmicrocavity in high magnetic field is predicted. While superfluid phase in this\nmagnetoexciton polariton system is absent due to vanishing of\nmagnetoexciton-magnetoexciton interaction in a single layer in the limit of\nhigh magnetic field, the critical temperature of BEC formation is calculated.\nThe essential property of magnetoexcitonic systems based on graphene (in\ncontrast, e.g., to a quantum well) is stronger influence of magnetic field and\nweaker influence of disorder. Observation of the BEC and superfluidity of 2D\nquasiparticles in graphene in high magnetic field would be interesting\nconfirmation of the phenomena we have described.",
        "positive": "Bosonization for fermions and parafermions: Parafermions are fractional excitations which can be regarded as\ngeneralizations of Majorana bound states, but in contrast to the latter they\nrequire electron-electron interactions. Compared to Majorana bound states, they\noffer richer non-Abelian braiding statistics, and have thus been proposed as\nbuilding blocks for topologically protected universal quantum computation. In\nthis review, we provide a pedagogical introduction to the field of parafermion\nbound states in one-dimensional systems. We present the necessary theoretical\ntools for their study, in particular bosonization and the renormalization-group\ntechnique, and show how those can be applied to study parafermions."
    },
    {
        "anchor": "Flux-tunable Josephson Effect in a Four-Terminal Junction: We study a phase-tunable four-terminal Josephson junction formed in an InSbAs\ntwo-dimensional electron gas proximitized by aluminum. By embedding the two\npairs of junction terminals in asymmetric DC SQUIDs we can control the\nsuperconducting phase difference across each pair, thereby gaining information\nabout their current-phase relation. Using a current-bias line to locally\ncontrol the magnetic flux through one SQUID, we measure a nonlocal Josephson\neffect, whereby the current-phase relation across two terminals in the junction\nis strongly dependent on the superconducting phase difference across two\ncompletely different terminals. In particular, each pair behaves as a\n$\\phi_0$-junction with a phase offset tuned by the phase difference across the\nother junction terminals. Lastly, we demonstrate that the behavior of an array\nof two-terminal junctions replicates most features of the current-phase\nrelation of different multiterminal junctions. This highlights that these\nsignatures alone are not sufficient evidence of true multiterminal Josephson\neffects arising from hybridization of Andreev bound states in the junction.",
        "positive": "Determining the phase diagram of atomically thin layered antiferromagnet\n  CrCl$_3$: Changes in the spin configuration of atomically-thin, magnetic van-der-Waals\nmultilayers can cause drastic modifications in their opto-electronic\nproperties. Conversely, the opto-electronic response of these systems provides\ninformation about the magnetic state, very difficult to obtain otherwise. Here\nwe show that in CrCl$_3$ multilayers, the dependence of the tunnelling\nconductance on applied magnetic field ($H$), temperature ($T$), and number of\nlayers ($N$) tracks the evolution of the magnetic state, enabling the magnetic\nphase diagram of these systems to be determined experimentally. Besides a\nhigh-field spin-flip transition occurring for all thicknesses, the in-plane\nmagnetoconductance exhibits an even-odd effect due to a low-field spin-flop\ntransition. If the layer number $N$ is even, the transition occurs at $\\mu_0 H\n\\sim 0$ T due to the very small in-plane magnetic anisotropy, whereas for odd\n$N$ the net magnetization of the uncompensated layer causes the transition to\noccur at finite $H$. Through a quantitative analysis of the phenomena, we\ndetermine the interlayer exchange coupling as well as the staggered\nmagnetization, and show that in CrCl$_3$ shape anisotropy dominates. Our\nresults reveal the rich behaviour of atomically-thin layered antiferromagnets\nwith weak magnetic anisotropy."
    },
    {
        "anchor": "Nonequilibrium Phases and Segregation for Skyrmions on Periodic Pinning\n  Arrays: Using particle-based simulations, we examine the collective dynamics of\nskyrmions interacting with periodic pinning arrays, focusing on the impact of\nthe Magnus force on the sliding phases. As a function of increasing pinning\nstrength, we find a series of distinct dynamical phases, including an\ninterstitial flow phase, a moving disordered state, a moving crystal, and a\nsegregated cluster state. The transitions between these states produce\nsignatures in the skyrmion lattice structure, the skyrmion Hall angle, the\nvelocity fluctuation distributions, and the velocity-force curves. The moving\nclustered state is similar to the segregated state recently observed in\ncontinuum-based simulations with strong quenched disorder. The segregation\narises from the drive dependence of the skyrmion Hall angle, and appears in the\nstrong pinning limit when the skyrmions have nonuniform velocities, causing\ndifferent portions of the sample to have different effective skyrmion Hall\nangles. We map the evolution of the dynamic phases as a function of the system\ndensity, the ratio of the Magnus force to the dissipative term, and the ratio\nof the number of skyrmions to the number of pinning sites.",
        "positive": "Resonators coupled to voltage-biased Josephson junctions: From linear\n  response to strongly driven nonlinear oscillations: Motivated by recent experiments, where a voltage biased Josephson junction is\nplaced in series with a resonator, the classical dynamics of the circuit is\nstudied in various domains of parameter space. This problem can be mapped onto\nthe dissipative motion of a single degree of freedom in a nonlinear\ntime-dependent potential, where in contrast to conventional settings the\nnonlinearity appears in the driving while the static potential is purely\nharmonic. For long times the system approaches steady states which are analyzed\nin the underdamped regime over the full range of driving parameters including\nthe fundamental resonance as well as higher and sub-harmonics. Observables such\nas the dc-Josephson current and the radiated microwave power give direct\ninformation about the underlying dynamics covering phenomena as bifurcations,\nirregular motion, up- and down conversion. Due to their tunability, present and\nfuture set-ups provide versatile platforms to explore the changeover from\nlinear response to strongly nonlinear behavior in driven dissipative systems\nunder well defined conditions."
    },
    {
        "anchor": "Edge optical scattering of two-dimensional materials: Rayleigh scattering has shown powerful abilities to study electron resonances\nof nanomaterials regardless of the specific shapes. In analogy to Rayleigh\nscattering, here we demonstrate that edge optical scattering from\ntwo-dimensional (2D) materials also has the similar advantage. Our result shows\nthat, in visible spectral range, as long as the lateral size of a 2D sample is\nlarger than 2 {\\mu}m, its edge scattering is essentially a knife-edge\ndiffraction, and the intensity distribution of the high-angle scattering in\n$\\mathbf{k}$ space is nearly independent of the lateral size and the shape of\nthe 2D samples. The high-angle edge scattering spectra are purely determined by\nthe intrinsic dielectric properties of the 2D materials. As an example, we\nexperimentally verify this feature in single-layer $MoS_{2}$, in which A and B\nexcitons are clearly detected in the edge scattering spectra, and the\nscattering images in $\\mathbf{k}$ space and real space are consistent with our\ntheoretical model. This study shows that the edge scattering is a highly\npractical and efficient method for optical studies of various 2D materials as\nwell as thin films with clear edges.",
        "positive": "Laser-Induced Magnetic Nanostructures with Tunable Topological\n  Properties: We report the creation and real-space observation of magnetic structures with\nwell-defined topological properties and a lateral size as low as about 150 nm.\nThey are generated in a thin ferrimagnetic film by ultrashort single optical\nlaser pulses. Thanks to their topological properties, such structures can be\nclassified as Skyrmions of a particular type that does not require an\nexternally applied magnetic field for stabilization. Besides Skyrmions, we are\nable to generate magnetic features with topological characteristics that can be\ntuned by changing the laser fluence. The stability of such features is\naccounted for by an analytical model based on the interplay between the\nexchange and the magnetic dipole-dipole interactions"
    },
    {
        "anchor": "Anharmonicity in Raman-active phonon modes in atomically thin MoS$_2$: Phonon-phonon anharmonic effects have a strong influence on the phonon\nspectrum; most prominent manifestation of these effects are the softening\n(shift in frequency) and broadening (change in FWHM) of the phonon modes at\nfinite temperature. Using Raman spectroscopy, we studied the temperature\ndependence of the FWHM and Raman shift of $\\mathrm{E_{2g}^1}$ and\n$\\mathrm{A_{1g}}$ modes for single-layer and natural bilayer MoS$_2$ over a\nbroad range of temperatures ($8 < $T$ < 300$ K). Both the Raman shift and FWHM\nof these modes show linear temperature dependence for $T>100$ K, whereas they\nbecome independent of temperature for $T<100$ K. Using first-principles\ncalculations, we show that three-phonon anharmonic effects intrinsic to the\nmaterial can account for the observed temperature-dependence of the line-width\nof both the modes. It also plays an important role in determining the\ntemperature-dependence of the frequency of the Raman modes. The observed\nevolution of the line-width of the A$_{1g}$ mode suggests that electron-phonon\nprocesses are additionally involved. From the analysis of the\ntemperature-dependent Raman spectra of MoS$_2$ on two different substrates --\nSiO$_2$ and hexagonal boron nitride, we disentangle the contributions of\nexternal stress and internal impurities to these phonon-related processes. We\nfind that the renormalization of the phonon mode frequencies on different\nsubstrates is governed by strain and intrinsic doping. Our work establishes the\nrole of intrinsic phonon anharmonic effects in deciding the Raman shift in\nMoS$_2$ irrespective of substrate and layer number.",
        "positive": "Self-assembly of tetracyanonaphtho-quinodimethane (TNAP) based\n  metal-organic networks on Pb(111): Structural, electronic, and magnetic\n  properties: We use scanning tunneling microscopy and spectroscopy to investigate\nstructural and electronic properties of tetracyanonaphtho-quinodimethane (TNAP)\nbased metal-organic networks on a superconducting Pb(111) surface. At low\ntemperatures, the TNAP molecules form densely packed islands. When deposited at\nroom temperature, Pb adatoms are incorporated into fourfold bonding nodes with\nthe TNAP molecules leading to long-range ordered porous structures.\nCo-deposition of NaCl with TNAP yields a Na source for an ionically bonded\nNa-TNAP structure. Fourfold bonding motifs are also created by Fe atoms with\nthe cyano terminations of TNAP. However, the structures are irregular and do\nnot sustain the formation of long-range ordered networks. Some Fe centers with\nmolecules surrounded in a local C2 symmetry exhibit Shiba states as a\nfingerprint of a magnetic interaction with the superconducting surface."
    },
    {
        "anchor": "Imaging and spectroscopy of artificial-atom states in core/shell\n  nanocrystal quantum dots: Current imaging scanning tunneling microscopy is used to observe the\nelectronic wavefunctions in InAs/ZnSe core/shell nanocrystals. Images taken at\na bias corresponding to the s conduction band state show that it is localized\nin the central core region, while images at higher bias probing the p state\nreveal that it extends to the shell. This is supported by optical and tunneling\nspectroscopy data demonstrating that the s-p gap closes upon shell growth.\nShapes of the current images resemble atom-like envelope wavefunctions of the\nquantum dot calculated within a particle in a box model.",
        "positive": "Inverse Orbital Torque via Spin-Orbital Entangled States: While current-induced torque by orbital current has been experimentally found\nin various structures, evidence for its reciprocity has been missing so far.\nHere, we report experimental evidence of strong inverse orbital torque in\nYIG/Pt/CuOx (YIG = Y3Fe5O12) mediated by spin-orbital entangled electronic\nstates in Pt. By injecting spin current from YIG to Pt by the spin pumping via\nferromagnetic resonance and by the spin Seebeck effect, we find a pronounced\ninverse spin Hall effect-like signal. While a part of the signal is explained\nas due to the inverse spin-orbital Hall effect in Pt, we also find substantial\nincrease of the signal in YIG/Pt/CuOx structures compared to the signal in\nYIG/Pt. We attribute this to the inverse orbital Rashba-Edelstein effect at\nPt/CuOx interface mediated by the spin-orbital entangled states in Pt. Our work\npaves the way toward understanding of spin-orbital entangled physics in\nnonequilibrium and provides a way for electrical detection of the orbital\ncurrent in orbitronic device applications."
    },
    {
        "anchor": "A simple microscopic description of quantum Hall transition without\n  Landau levels: By restricting the motion of high-mobility 2D electron gas to a network of\nchannels with smooth confinement, we were able to trace, both classically and\nquantum-mechanically, the interplay of backscattering, and of the bending\naction of a weak magnetic field. Backscattering limits the mobility, while\nbending initiates quantization of the Hall conductivity. We demonstrate that,\nin restricted geometry, electron motion reduces to two Chalker-Coddington\nnetworks, with opposite directions of propagation along the links, which are\nweakly coupled by disorder. Interplay of backscattering and bending results in\nthe quantum Hall transition in a non-quantizing magnetic field, which decreases\nwith increasing mobility. This is in accord with scenario of floating up\ndelocalized states.",
        "positive": "Mesoscopic Hall effect driven by chiral spin order: A Hall effect due to spin chirality in mesoscopic systems is predicted. We\nconsider a 4-terminal Hall system including local spins with geometry of a\nvortex domain wall, where strong spin chirality appears near the center of\nvortex. The Fermi energy of the conduction electrons is assumed to be\ncomparable to the exchange coupling energy where the adiabatic approximation\nceases to be valid. Our results show a Hall effect where a voltage drop and a\nspin current arise in the transverse direction. The similarity between this\nHall effect and the conventional spin Hall effect in systems with spin-orbit\ninteraction is pointed out."
    },
    {
        "anchor": "Linking boundary conditions for kinetic and hydrodynamic description of\n  fermion gas: An approximate analytical solution of the boundary slip problem in magnetic\nfield is obtained by using the general form of boundary conditions for the\ndistribution function of fermions with the isotropic energy spectrum. Exact\nnumerical calculations of the slip length for different models of\nangle-dependent specularity parameter and application of the results to the\ndescription of the Poiseuille flow demonstrate the reliability of the\napproximate solution for establishing a direct link between the hydrodynamic\nand the kinetic approaches to transport in bounded fermion systems.",
        "positive": "Interplay of different environments in open quantum systems: Breakdown\n  of the additive approximation: We analyze an open quantum system under the influence of more than one\nenvironment: a dephasing bath and a probability-absorbing bath that represents\na decay channel, as encountered in many models of quantum networks. In our\ncase, dephasing is modeled by random fluctuations of the site energies, while\nthe absorbing bath is modeled with an external lead attached to the system. We\nanalyze under which conditions the effects of the two baths can enter\nadditively the quantum master equation. When such additivity is legitimate, the\nreduced master equation corresponds to the evolution generated by an effective\nnon-Hermitian Hamiltonian and a Haken-Strobl dephasing super-operator. We find\nthat the additive decomposition is a good approximation when the strength of\ndephasing is small compared to the bandwidth of the probability-absorbing bath."
    },
    {
        "anchor": "Comment on ``Evidence for Anisotropic State of Two-Dimensional Electrons\n  in High Landau Levels'': In a recent letter M. Lilly et al [PRL 82, 394 (1999)] have shown that a\nhighly anisotropic state can arise in certain two dimensional electron systems.\nIn the large square samples studied, resistances measured in the two\nperpendicular directions are found to have a ratio that may be 60 or larger at\nlow temperature and at certain magnetic fields. In Hall bar measurements, the\nanisotropy ratio is found to be much smaller (roughly 5). In this comment we\nresolve this discrepancy by noting that the anisotropy of the underlying sheet\nresistivities is correctly represented by Hall bar resistance measurements but\nshows up exponentially enhanced in resistance measurements on square samples\ndue to simple geometric effects. We note, however, that the origin of this\nunderlying resistivity anisotropy remains unknown, and is not addressed here.",
        "positive": "Magnetic anisotropy of elongated thin ferromagnetic nano-islands for\n  artifical spin ice arrays: The energetics of thin elongated ferromagnetic nano-islands is considered for\nsome different shapes, aspect ratios, and applied magnetic field directions.\nThese nano-island particles are important for artificial spin-ice materials.\nFor low temperature, the magnetic internal energy of an individual particle is\nevaluated numerically as a function of the direction of a particle's net\nmagnetization. This leads to estimations of effective anisotropy constants for\n(1) the easy axis along the particle's long direction, and (2) the hard axis\nalong the particle's thin direction. A spin relaxation algorithm together with\nfast Fourier transform for the demagnetization field is used to solve the\nmicromagnetics problem for a thin system. The magnetic hysteresis is also\nfound. The results indicate some possibilities for controlling the equilibrium\nand dynamics in spin-ice materials by using different island geometries."
    },
    {
        "anchor": "Nanomechanical absorption spectroscopy of 2D materials with femtowatt\n  sensitivity: Nanomechanical spectroscopy (NMS) is a recently developed approach to\ndetermine optical absorption spectra of nanoscale materials via mechanical\nmeasurements. It is based on measuring changes in the resonance frequency of a\nmembrane resonator vs. the photon energy of incoming light. This method is a\ndirect measurement of absorption, which has practical advantages compared to\ncommon optical spectroscopy approaches. In the case of two-dimensional (2D)\nmaterials, NMS overcomes limitations inherent to conventional optical methods,\nsuch as the complications associated with measurements at high magnetic fields\nand low temperatures. In this work, we develop a protocol for NMS of 2D\nmaterials that yields two orders of magnitude improved sensitivity compared to\nprevious approaches, while being simpler to use. To this end, we use electrical\nsample actuation, which simplifies the experiment and provides a reliable\ncalibration for greater accuracy. Additionally, the use of low-stress silicon\nnitride membranes as our substrate reduces the noise-equivalent power to $NEP =\n890 fW/\\sqrt{Hz}$, comparable to commercial semiconductor photodetectors. We\nuse our approach to spectroscopically characterize a two-dimensional transition\nmetal dichalcogenide (WS$_2$), a layered magnetic semiconductor (CrPS$_4$), and\na plasmonic supercrystal consisting of gold nanoparticles.",
        "positive": "A scanning tunneling microscope capable of electron spin resonance and\n  pump-probe spectroscopy at mK temperature and in vector magnetic field: In the last decade, detecting spin dynamics at the atomic scale has been\nenabled by combining techniques like electron spin resonance (ESR) or\npump-probe spectroscopy with scanning tunneling microscopy (STM). Here, we\ndemonstrate an ultra-high vacuum (UHV) STM operational at milliKelvin (mK) and\nin a vector magnetic field capable of both ESR and pump-probe spectroscopy. By\nimplementing GHz compatible cabling, we achieve appreciable RF amplitudes at\nthe junction while maintaining mK base temperature. We demonstrate the\nsuccessful operation of our setup by utilizing two experimental ESR modes\n(frequency sweep and magnetic field sweep) on an individual TiH molecule on\nMgO/Ag(100) and extract the effective g-factor. We trace the ESR transitions\ndown to MHz into an unprecedented low frequency band enabled by the mK base\ntemperature. We also implement an all-electrical pump-probe scheme based on\nwaveform sequencing suited for studying dynamics down to the nanoseconds range.\nWe benchmark our system by detecting the spin relaxation time T1 of individual\nFe atoms on MgO/Ag(100) and note a field strength and orientation dependent\nrelaxation time."
    },
    {
        "anchor": "Current-driven dynamics of coupled domain walls in a synthetic\n  antiferromagnet: We develop the theory of magnetic domain wall motion in coupled double-layer\nsystems where electrons can hop between the layers giving rise to an\nantiferromagnetic coupling. We demonstrate that the force from the interlayer\ncoupling drives the walls and the effect of the extrinsic pinning is greatly\nreduced if the domain walls are initially separated. The threshold current\ndensity for metastable spin-aligned configurations is also much lower. We\nconclude that the interlayer coupling has a significant effect on domain wall\nmobility in double-layer systems.",
        "positive": "Photoemission Spectroscopic Evidence for the Dirac Nodal Line in\n  Monoclinic Semimetal SrAs$_3$: Topological nodal-line semimetals with exotic quantum properties are\ncharacterized by symmetry-protected line-contact bulk band crossings in the\nmomentum space. However, in most of identified topological nodal-line\ncompounds, these topological non-trivial nodal lines are enclosed by\ncomplicated topological trivial states at the Fermi energy ($E_F$), which would\nperplex their identification and hinder further applications. Utilizing\nangle-resolved photoemission spectroscopy and first-principles calculations, we\nprovide compelling evidence for the existence of Dirac nodal-line fermions in\nthe monoclinic semimetal SrAs$_3$, which are close to $E_F$ and away from\ndistraction of complex trivial Fermi surfaces or surface states. Our\ncalculation indicates that two bands with opposite parity are inverted around\n\\emph{Y} near $E_F$, which results in the single nodal loop at the\n$\\Gamma$-\\emph{Y}-\\emph{S} plane with a negligible spin-orbit coupling effect.\nWe track these band crossings and then unambiguously identify the complete\nnodal loop quantitatively, which provides a critical experimental support to\nthe prediction of nodal-line fermions in the CaP$_3$ family of materials.\nHosting simple topological non-trivial bulk electronic states around $E_F$ and\nno interfering with surface states on the natural cleavage plane, SrAs$_3$ is\nexpected to be a potential platform for topological quantum state investigation\nand applications."
    },
    {
        "anchor": "Energy spectra for quantum wires and 2DEGs in magnetic fields with\n  Rashba and Dresselhaus spin-orbit interactions: We introduce an analytical approximation scheme to diagonalize parabolically\nconfined two dimensional electron systems with both the Rashba and Dresselhaus\nspin-orbit interactions. The starting point of our perturbative expansion is a\nzeroth-order Hamiltonian for an electron confined in a quantum wire with an\neffective spin-orbit induced magnetic field along the wire, obtained by\nproperly rotating the usual spin-orbit Hamiltonian. We find that the\nspin-orbit-related transverse coupling terms can be recast into two parts W and\nV, which couple crossing and non-crossing adjacent transverse modes,\nrespectively. Interestingly, the zeroth-order Hamiltonian together with W can\nbe solved exactly, as it maps onto the Jaynes-Cummings model of quantum optics.\nWe treat the V coupling by performing a Schrieffer-Wolff transformation. This\nallows us to obtain an effective Hamiltonian to third order in the coupling\nstrength k_Rl of V, which can be straightforwardly diagonalized via an\nadditional unitary transformation. We also apply our approach to other types of\neffective parabolic confinement, e.g., 2D electrons in a perpendicular magnetic\nfield. To demonstrate the usefulness of our approximate eigensolutions, we\nobtain analytical expressions for the n^th Landau-level g_n-factors in the\npresence of both Rashba and Dresselhaus couplings. For small values of the bulk\ng-factors, we find that spin-orbit effects cancel out entirely for particular\nvalues of the spin-orbit couplings. By solving simple transcendental equations\nwe also obtain the band minima of a Rashba-coupled quantum wire as a function\nof an external magnetic field. These can be used to describe Shubnikov-de Haas\noscillations. This procedure makes it easier to extract the strength of the\nspin-orbit interaction in these systems via proper fitting of the data.",
        "positive": "Microwave control of thermal magnon spin transport: We observe that an rf microwave field strongly influences the transport of\nincoherent thermal magnons in yttrium iron garnet. Ferromagnetic resonance in\nthe nonlinear regime suppresses thermal magnon transport by 95%. The transport\nis also modulated at non-resonant conditions in two cases, both related to the\nmagnon band minimum. Firstly, a strong enhancement of the nonlocal signal\nappears at a static magnetic field below the resonance condition. This increase\nonly occurs at one field polarity and can be as large as 800%. We attribute\nthis effect to magnon kinetic processes, which give rise to band-minimum\nmagnons and high-energy chiral surface modes. Secondly, the signal increases at\na static field above the resonance condition, where the rf frequency coincides\nwith the magnon band minimum. Our study gives insight into the interplay\nbetween coherent and incoherent spin dynamics: The rf field modifies the\noccupation of relevant magnon states and, via kinetic processes, the magnon\nspin transport."
    },
    {
        "anchor": "Topological phase transitions driven by next-nearest-neighbor hopping in\n  two-dimensional lattices: For two-dimensional lattices in a tight-binding description, the intrinsic\nspin-orbit coupling, acting as a complex next-nearest-neighbor hopping, opens\ngaps that exhibit the quantum spin Hall effect. In this paper, we study the\neffect of a real next-nearest-neighbor hopping term on the band structure of\nseveral Dirac systems. In our model, the spin is conserved, which allows us to\nanalyze the spin Chern numbers. We show that in the Lieb, kagome, and T_3\nlattices, variation of the amplitude of the real next-nearest-neighbor hopping\nterm drives interesting topological phase transitions. These transitions may be\nexperimentally realized in optical lattices under shaking, when the ratio\nbetween the nearest- and next-nearest-neighbor hopping parameters can be tuned\nto any possible value. Finally, we show that in the honeycomb lattice,\nnext-nearest-neighbor hopping only drives topological phase transitions in the\npresence of a magnetic field, leading to the conjecture that these transitions\ncan only occur in multigap systems.",
        "positive": "Ab initio studies of the spin-transfer torque in tunnel junctions: We calculate the spin-transfer torque in Fe/MgO/Fe tunnel junctions and\ncompare the results to those for all-metallic junctions. We show that the\nspin-transfer torque is interfacial in the ferromagnetic layer to a greater\ndegree than in all-metallic junctions. This result originates in the half\nmetallic behavior of Fe for the $\\Delta_1$ states at the Brillouin zone center;\nin contrast to all-metallic structures, dephasing does not play an important\nrole. We further show that it is possible to get a component of the torque that\nis out of the plane of the magnetizations and that is linear in the bias.\nHowever, observation of such a torque requires highly ideal samples. In samples\nwith typical interfacial roughness, the torque is similar to that in\nall-metallic multilayers, although for different reasons."
    },
    {
        "anchor": "Microscopic theory of fractional excitations in gapless bilayer quantum\n  Hall states: semi-quantized quantum Hall states: We derive the low-energy theory of semi-quantized quantum Hall states, a\nrecently observed class of gapless bilayer fractional quantum Hall states. Our\ntheory shows these states to feature gapless quasiparticles of fractional\ncharge coupled to an emergent Chern-Simons gauge field. These gapless\nquasiparticles can be understood as composites of electrons and Laughlin-like\nquasiparticles. We show that semi-quantized quantum Hall states exhibit perfect\ninterlayer drag, host non-Fermi liquid physics, and serve as versatile parent\nstates for fully gapped topological phases hosting anyonic excitations.",
        "positive": "Resonant quenching of Raman scattering due to out-of-plane\n  A$_{1g}$/A'$_1$ modes in few-layer MoTe$_2$: Temperature-dependent (5 K to 300 K) Raman scattering study of\nA$_{1g}$/A'$_1$ phonon modes in mono-layer (1L), bilayer (2L), trilayer (3L),\nand tetralayer (4L) MoTe$_2$ is reported. The temperature evolution of the\nmodes' intensity critically depends on the flake thickness. In particular with\n$\\lambda$=632.8 nm light excitation, a strongly non-monotonic dependence of the\nA$_{1g}$ mode intensity is observed in 2L MoTe$_2$. The intensity decreases\nwith decreasing temperature down to 220 K and the A$_{1g}$ mode almost\ncompletely vanishes from the Stokes scattering spectrum in the temperature\nrange between 160 K and 220 K. The peak recovers at lower temperatures and at\nT=5 K it becomes three times more intense that at room temperature. Similar\nnon-monotonic intensity evolution is observed for the out-of-plane mode in 3L\nMoTe$_2$ in which tellurium atoms in all three layers vibrate in-phase. The\nintensity of the other out-of-plane Raman-active mode, (with vibrations of\ntellurium atoms in the central layer shifted by 180$^o$ with respect to the\nvibrations in outer layers), only weakly depends on temperature. The observed\nquenching of the Raman scattering in 2L and 3L MoTe$_2$ is attributed to a\ndestructive interference between the resonant and non-resonant contributions to\nthe Raman scattering amplitude. The observed \"antiresonance\" is related to the\nelectronic excitation at the M point of the Brillouin zone in few-layer\nMoTe$_2$."
    },
    {
        "anchor": "Kinetics of Topological Stone-Wales Defect Formation in Single Walled\n  Carbon: Topological Stone-Wales defect in carbon nanotubes plays a central role in\nplastic deformation, chemical functionalization, and superstructure formation.\nHere, we systematically investigate the formation kinetics of such defects\nwithin density functional approach coupled with the transition state theory. We\nfind that both the formation and activation energies depend critically on the\nnanotube chairality, diameter, and defect orientation. The microscopic origin\nof the observed dependence is explained with curvature induced rehybridization\nin nanotube. Surprisingly, the kinetic barrier follows an empirical\nBr{\\o}nsted-Evans-Polanyi type correlation with the corresponding formation\nenergy, and can be understood in terms of overlap between energy-coordinate\nparabolas representing the structures with and without the defect. Further, we\npropose a possible route to substantially decrease the kinetic activation\nbarrier. Such accelerated rates of defect formation are desirable in many novel\nelectronic, mechanical and chemical applications, and also facilitate the\nformation of three-dimensional nanotube superstructures.",
        "positive": "Spin-dependent Andreev reflection in spin-orbit coupled systems by\n  breaking time-reversal symmetry: We study theoretically the differential conductance at a junction between a\ntime reversal symmetry broken spin orbit coupled system with a tunable band gap\nand a superconductor. We look for spin-dependent Andreev reflection (i.e,\nsub-gap transport) and show that when various mass terms compete in energy,\nthere is substantial difference of Andreev reflection probability depending on\nthe spin of the incident electron. We further analyze the origin of such\nspin-dependence and show how the incident angle of the electrons controls the\nspin-dependence of the transport."
    },
    {
        "anchor": "Temperature and thickness dependence of tunneling anisotropic\n  magnetoresistance in exchange-biased Py/IrMn/MgO/Ta stacks: We investigate the thickness and temperature dependence of a series of\nNi0:8Fe0:2/Ir0:2Mn0:8 bilayer samples with varying thickness ratio of the\nferromagnet/antiferromagnet (tFM/tAFM) in order to explore the exchange\ncoupling strengths in tunneling anisotropic magnetoresistance (TAMR) devices.\nSpecific values of tFM/tAFM lead to four distinct scenarios with specific\nelectric responses to moderate magnetic fields. The characteristic dependence\nof the measured TAMR signal on applied voltage allows us to confirm its\npersistence up to room temperature despite an overlapped contribution by a\nthermal magnetic noise.",
        "positive": "Room temperature antiferromagnetic resonance and inverse spin-Hall\n  voltage in canted antiferromagnets: We study theoretically and experimentally the spin pumping signals induced by\nthe resonance of canted antiferromagnets with Dzyaloshinskii-Moriya interaction\nand demonstrate that they can generate easily observable inverse spin-Hall\nvoltages. Using a bilayer of hematite/heavy metal as a model system, we measure\nat room temperature the antiferromagnetic resonance and an associated inverse\nspin-Hall voltage, as large as in collinear antiferromagnets. As expected for\ncoherent spin-pumping, we observe that the sign of the inverse spin-Hall\nvoltage provides direct information about the mode handedness as deduced by\ncomparing hematite, chromium oxide and the ferrimagnet Yttrium-Iron Garnet. Our\nresults open new means to generate and detect spin-currents at terahertz\nfrequencies by functionalizing antiferromagnets with low damping and canted\nmoments."
    },
    {
        "anchor": "Electromechanical instability in vibrating quantum dots with effectively\n  negative charging energy: In quantum dots or molecules with vibrational degrees of freedom the\nelectron-vibron coupling renormalizes the electronic charging energy. For\nsufficiently strong coupling, the renormalized charging energy can become\nnegative. Here, we discuss an instability towards adding or removing an\narbitrary number of electrons when the magnitude of the renormalized charging\nenergy exceeds the single-particle level spacing. We show that the instability\nis regularized by the anharmonic contribution to the vibron energy. The\nresulting effective charging energy as a function of the electron number has a\ndouble-well structure causing a variety of novel features in the Coulomb\nblockade properties.",
        "positive": "Deterministic topological quantum gates for Majorana qubits without\n  ancillary modes: The realization of quantum gates in topological quantum computation still\nconfronts significant challenges in both fundamental and practical aspects.\nHere, we propose a deterministic and fully topologically protected\nmeasurement-based scheme to realize the issue of implementing Clifford quantum\ngates on the Majorana qubits. Our scheme is based on rigorous proof that the\nsingle-qubit gate can be performed by leveraging the neighboring Majorana qubit\nbut not disturbing its carried quantum information, eliminating the need for\nancillary Majorana zero modes (MZMs) in topological quantum computing.\nBenefiting from the ancilla-free construction, we show the minimum measurement\nsequences with four steps to achieve two-qubit Clifford gates by constructing\ntheir geometric visualization. To avoid the uncertainty of the measurement-only\nstrategy, we propose manipulating the MZMs in their parameter space to correct\nthe undesired measurement outcomes while maintaining complete topological\nprotection, as demonstrated in a concrete Majorana platform. Our scheme\nidentifies the minimal operations of measurement-based topological and\ndeterministic Clifford gates and offers an ancilla-free design of topological\nquantum computation."
    },
    {
        "anchor": "Many-Body Physics and Quantum Chaos: Experimental progresses in the miniaturisation of electronic devices have\nmade routinely available in the laboratory small electronic systems, on the\nmicron or sub-micron scale, which at low temperature are sufficiently well\nisolated from their environment to be considered as fully coherent. Some of\ntheir most important properties are dominated by the interaction between\nelectrons. Understanding their behaviour therefore requires a description of\nthe interplay between interference effects and interactions.\n  The goal of this review is to address this relatively broad issue, and more\nspecifically to address it from the perspective of the quantum chaos community.\nI will therefore present some of the concepts developed in the field of quantum\nchaos which have some application to study many-body effects in mesoscopic and\nnanoscopic systems. Their implementation is illustrated on a few examples of\nexperimental relevance such as persistent currents, mesoscopic fluctuations of\nKondo properties or Coulomb blockade. I will furthermore try to bring out, from\nthe various physical illustrations, some of the specific advantages on more\ngeneral grounds of the quantum chaos based approach.",
        "positive": "Strong Cavity-Pseudospin Coupling in Monolayer Transition Metal\n  Dichalcogenides: Spontaneous Spin-Oscillations and Magnetometry: Strong coupling between the electronic states of monolayer transition metal\ndichalcogenides (TMDC) such as MoS$_2$, MoSe$_2$, WS$_2$, or WSe$_2$, and a\ntwo-dimensional (2D) photonic cavity gives rise to several exotic effects. The\nDirac type Hamiltonian for a 2D gapped semiconductor with large spin-orbit\ncoupling facilitates pure Jaynes-Cummings type coupling in the presence of a\nsingle mode electric field. The presence of an additional circularly polarized\nbeam of light gives rise to valley and spin dependent cavity-QED properties.\nThe cavity causes the TMDC monolayer to act as an on-chip coherent light source\nand a spontaneous spin-oscillator. In addition, a TMDC monolayer in a cavity is\na sensitive magnetic field sensor for an in-plane magnetic field."
    },
    {
        "anchor": "Enhanced Robustness of Zero-line Modes in Graphene via a Magnetic Field: Motivated by recent experimental results for zero-line modes (ZLMs) in a\nbilayer graphene system [Nature Nanotechnol. 11, 1060 (2016)], we\nsystematically studied the influence of a magnetic field on ZLMs and\ndemonstrated the physical origin of the enhanced robustness by employing\nnonequilibrium Green's functions and the Landauer-Buttiker formula. We found\nthat a perpendicular magnetic field can separate the wavefunctions of the\ncounter-propagating kink states into opposite directions. Specifically, the\nseparation vanishes at the charge neutrality point. The separation increases as\nthe Fermi level deviates from the charge neutrality point and can reach a\nmagnitude comparable to the wavefunction spread at a moderate field strength.\nSuch spatial separation of oppositely propagating ZLMs effectively suppresses\nbackscattering. Moreover, the presence of a magnetic field enlarges the bulk\ngap and suppresses the bound states, thereby further reducing the scattering.\nThese mechanisms effectively increase the mean free paths of the ZLMs to\napproximately 1 micron in the presence of a disorder.",
        "positive": "Fermion condensation around a Coulomb impurity in a Weyl semimetal and\n  in a narrow band gap semiconductor as manifestations of the Landau\n  zero-charge problem: A Coulomb impurity placed in an undoped Weyl semimetal spontaneously\nsurrounds itself with a cloud of condensed Weyl fermions. We find that the\nground-state of this system exhibits an experimentally accessible Landau\nzero-charge effect: the fermion condensate completely screens out the impurity\ncharge. In a narrow band gap semiconducor this effect manifests itself in the\nnear universality of observable charge of a highly-charged recombination\ncenter."
    },
    {
        "anchor": "Theoretical evidence of a significant modification of the electronic\n  structure of double-walled carbon nanotubes due to the interlayer interaction: The recently reported experimental optical spectra of double-walled carbon\nnanotubes exhibit more peaks than it could be expected based on the layers\nalone. The appearance of excess peaks has been attributed to the interlayer\ninteraction. In order to elucidate the origin of the excess peaks, we perform\ncalculations of the optical absorption of a particular nanotube using the\nrecursion method with non-orthogonal tight-binding basis functions. Our study\nshows that the interlayer interaction can give rise to major changes in the\nelectronic structure of this nanotube, manifesting themselves with shifts of\nthe optical transitions and appearance of new optical transitions. The derived\nabsorption spectrum is found to be in excellent agreement with the available\nexperimental data, which justifies the use of the proposed approach for\ndouble-walled carbon nanotubes.",
        "positive": "Gilbert Damping in Conducting Ferromagnets I: Kohn-Sham Theory and\n  Atomic-Scale Inhomogeneity: We derive an approximate expression for the Gilbert damping coefficient\n\\alpha_G of itinerant electron ferromagnets which is based on their description\nin terms of spin-density-functional-theory (SDFT) and Kohn-Sham quasiparticle\norbitals. We argue for an expression in which the coupling of magnetization\nfluctuations to particle-hole transitions is weighted by the spin-dependent\npart of the theory's exchange-correlation potential, a quantity which has large\nspatial variations on an atomic length scale. Our SDFT result for \\alpha_G is\nclosely related to the previously proposed spin-torque correlation-function\nexpression."
    },
    {
        "anchor": "The effect of sample properties on the electron velocity in quantum Hall\n  bars: We report on our theoretical investigation of the effects of the confining\npotential profile and sample size on the electron velocity distribution in\n(narrow) quantum-Hall systems. The electrostatic properties of the electron\nsystem are obtained by the Thomas-Fermi-Poisson nonlinear screening theory. The\nelectron velocity distribution as a function of the lateral coordinate is\nobtained from the slope of the screened potential at the Fermi level and within\nthe incompressible strips (ISs). We compare our findings with the recent\nexperiments.",
        "positive": "Nanoflows through disordered media: a joint Lattice Boltzmann and\n  Molecular Dynamics investigation: We investigate nanoflows through dilute disordered media by means of joint\nlattice Boltzmann (LB) and molecular dynamics (MD) simulations -- when the size\nof the obstacles is comparable to the size of the flowing particles -- for\nrandomly located spheres and for a correlated particle-gel. In both cases at\nsufficiently low solid fraction, $\\Phi<0.01$, LB and MD provide similar values\nof the permeability. However, for $\\Phi > 0.01$, MD shows that molecular size\neffects lead to a decrease of the permeability, as compared to the\nNavier-Stokes predictions. For gels, the simulations highlights a surplus of\npermeability, which can be accommodated within a rescaling of the effective\nradius of the gel monomers."
    },
    {
        "anchor": "Terahertz Magnetospectroscopy of Cyclotron Resonances from Topological\n  Surface States in Thick Films of Cd$_x$Hg$_{1-x}$Te: We present studies of the cyclotron resonance (CR) in thick\nCd$_x$Hg$_{1-x}$Te films with different cadmium concentrations corresponding to\ninverted and normal band order, as well as to an almost linear energy\ndispersion. Our results demonstrate that formation of two-dimensional\ntopological surface states requires sharp interfaces between layers with\ninverted and normal band order, in which case the corresponding CR is clearly\nobserved for the out-of-plane orientation of magnetic field, but does not show\nup for an in-plane orientation. By contrast, all samples having more\nconventional technological design with smooth interfaces (i.e., containing\nregions of Cd$_x$Hg$_{1-x}$Te with gradually changing Cd content $x$) show\nequally pronounced CR in both in-plane and out-of-plane magnetic field\nrevealing that CR is excited in three-dimensional states. Modeling of the\nsurface states for different film designs supports our main observations. In\nall samples, we observe additional broad helicity-independent resonances which\nare attributed to photo-ionization and magnetic freeze-out of impurity states.",
        "positive": "Classical information driven quantum dot thermal machines: We analyze the transient response of quantum dot thermal machines that can be\ndriven by hyperfine interaction acting as a source of classical information.\nOur setup comprises a quantum dot coupled to two contacts that drive heat flow\nwhile coupled to a nuclear spin bath. The quantum dot thermal machines operate\nboth as batteries and as engines, depending on the parameter range. The\nelectrons in the quantum dot interact with the nuclear spins via hyperfine\nspin-flip processes as typically seen in solid state systems such as GaAs\nquantum dots. The hyperfine interaction in such systems, which is often treated\nas a deterrent for quantum information processing, can favorably be regarded as\na driving agent for classical information flow into a heat engine setup. We\nrelate this information flow to Landauer's erasure of the nuclear spin bath,\nleading to a battery operation. We further demonstrate that the setup can\nperform as a transient power source even under a voltage bias across the dot.\nFocusing on the transient thermoelectric operation, our analysis clearly\nindicates the role of Landauer's erasure to deliver a higher output power than\na conventional quantum dot thermoelectric setup and an efficiency greater than\nthat of an identical Carnot cycle in steady state, which is consistent with\nrecently proposed bounds on efficiency for systems subject to a feedback\ncontroller. The role of nuclear spin relaxation processes on these aspects is\nalso studied. Finally, we introduce the Coulomb interaction in the dot and\nanalyze the transient thermoelectric response of the system. Our results\nelaborate on the effective use of somewhat undesirable scattering processes as\na non-equilibrium source of Shannon information flow in thermal machines and\nthe possibilities that may arise from the use of a quantum information source."
    },
    {
        "anchor": "Andreev Bound States in the Kondo Quantum Dots Coupled to\n  Superconducting Leads: We have studied the Kondo quantum dot coupled to two superconducting leads\nand investigated the subgap Andreev states using the NRG method. Contrary to\nthe recent NCA results [Clerk and Ambegaokar, Phys. Rev. B 61, 9109 (2000);\nSellier et al., Phys. Rev. B 72, 174502 (2005)], we observe Andreev states both\nbelow and above the Fermi level.",
        "positive": "Unique Electron Spin Relaxation Induced by Confined Phonons in\n  Nanowire-Based Quantum Dots: Electron spin relaxation in nanowire-based quantum dots induced by confined\nphonons is investigated theoretically. Due to the one-dimensional nature of the\nconfined phonons, the van Hove singularities of the confined phonons and the\nzero of the form factor of the electron-phonon coupling can lead to unique\nfeatures of the spin relaxation rate. Extremely strong spin relaxation can be\nobtained at the van Hove singularity. Meanwhile the spin relaxation rate can\nalso be greatly suppressed at the zero of the form factor. This unique feature\nindicates the flexibility of nanowire-based quantum dots in the manipulation of\nspin states. It also offers a way to probe the property of the confined\nphonons."
    },
    {
        "anchor": "Effect of transverse anisotropy on inelastic tunneling spectroscopy of\n  atomic-scale magnetic chains: We theoretically investigate the effect of transverse magnetic anisotropy on\nspin-flip assisted tunneling through atomic spin chains. Using a\nphenomenological approach and first-order perturbation theory, we analytically\ncalculate the inelastic tunneling current, differential conductance and atomic\nspin transition rates. We predict the appearance of additional steps in the\ndifferential conductance and a pronounced increase in the spin-flip transition\nrate which at low voltages scale quadratically with the ratio of the transverse\nanisotropy energy and the sum of the longitudinal anisotropy energy and the\nexchange energy. Our results provide intuitive quantitative insight in the role\nplayed by transverse anisotropy in inelastic tunneling spectroscopy of atomic\nchains and can be observed under realistic experimental conditions.",
        "positive": "Non-Hermitian Physics: A review is given on the foundations and applications of non-Hermitian\nclassical and quantum physics. First, key theorems and central concepts in\nnon-Hermitian linear algebra, including Jordan normal form, biorthogonality,\nexceptional points, pseudo-Hermiticity and parity-time symmetry, are delineated\nin a pedagogical and mathematically coherent manner. Building on these, we\nprovide an overview of how diverse classical systems, ranging from photonics,\nmechanics, electrical circuits, acoustics to active matter, can be used to\nsimulate non-Hermitian wave physics. In particular, we discuss rich and unique\nphenomena found therein, such as unidirectional invisibility, enhanced\nsensitivity, topological energy transfer, coherent perfect absorption,\nsingle-mode lasing, and robust biological transport. We then explain in detail\nhow non-Hermitian operators emerge as an effective description of open quantum\nsystems on the basis of the Feshbach projection approach and the quantum\ntrajectory approach. We discuss their applications to physical systems relevant\nto a variety of fields, including atomic, molecular and optical physics,\nmesoscopic physics, and nuclear physics with emphasis on prominent\nphenomena/subjects in quantum regimes, such as quantum resonances,\nsuperradiance, continuous quantum Zeno effect, quantum critical phenomena,\nDirac spectra in quantum chromodynamics, and nonunitary conformal field\ntheories. Finally, we introduce the notion of band topology in complex spectra\nof non-Hermitian systems and present their classifications by providing the\nproof, firstly given by this review in a complete manner, as well as a number\nof instructive examples. Other topics related to non-Hermitian physics,\nincluding nonreciprocal transport, speed limits, nonunitary quantum walk, are\nalso reviewed."
    },
    {
        "anchor": "Efficient characteristics of exchange coupling and spin-flop transition\n  in Py/Gd bilayer using anisotropic magnetoresistance: The interlayer antiferromagnetic coupling rare-earth/transition-metal bilayer\nferrimagnet systems have attracted much attention because they present\nvariously unusual temperature-and field-dependent nontrivial magnetic states\nand dynamics. These properties and the implementation of their applications in\nspintronics highly depend on the significant temperature dependence of the\nmagnetic exchange stiffness constant A. Here, we quantitatively determine the\ntemperature dependence of magnetic exchange stiffness A_{Py-Gd} and A_{Gd} in\nthe artificially layered ferrimagnet consisting of a Py/Gd bilayer, using a\nmeasurement of anisotropic magnetoresistance (AMR) of the bilayer thin film at\ndifferent temperatures and magnetic fields. The obtained temperature dependence\nof A_{Py-Gd} and A_{Gd} exhibit a scaling power law with the magnetization of\nGd. The critical field of spin-flop transition and its temperature dependence\ncan also be directly obtained by this method. Additionally, the experimental\nresults are well reproduced by micromagnetic simulations with the obtained\nparameters A_{Py-Gd} and A_{Gd}, which further confirms the reliability of this\neasily accessible technique.",
        "positive": "Fast tuning of superconducting microwave cavities: Photons are fundamental excitations of the electromagnetic field and can be\ncaptured in cavities. For a given cavity with a certain size, the fundamental\nmode has a fixed frequency {\\it f} which gives the photons a specific \"color\".\nThe cavity also has a typical lifetime $\\tau$, which results in a finite\nlinewidth $\\delta${\\it f}. If the size of the cavity is changed fast compared\nto $\\tau$, and so that the frequency change $\\Delta${\\it f} $\\gg \\delta${\\it\nf}, then it is possible to change the \"color\" of the captured photons. Here we\ndemonstrate superconducting microwave cavities, with tunable effective lengths.\nThe tuning is obtained by varying a Josephson inductance at one end of the\ncavity. We show data on four different samples and demonstrate tuning by\nseveral hundred linewidths in a time $\\Delta t \\ll \\tau$. Working in the few\nphoton limit, we show that photons stored in the cavity at one frequency will\nleak out from the cavity with the new frequency after the detuning. The\ncharacteristics of the measured devices make them suitable for different\napplications such as dynamic coupling of qubits and parametric amplification."
    },
    {
        "anchor": "Nonlinear optical responses of all-inorganic lead halide perovskite\n  nanostructures by time-resolved beam-deflection technique: We have investigated nonlinear refraction in all-inorganic halide\nperovskites, the CsPbBr$_3$ and CsPbBr$_{1.5}$I$_{1.5}$ nanosheet and quantum\ndot colloids in toluene, by a novel beam deflection technique using\nnear-resonant continuous wave lasers. The nonlinear refraction and its\ntime-evolution measured here have originated from thermal lensing effect.\nNonlinear behaviour of heat transport in terms of intensity dependent thermal\ndiffusion rate has been observed. Effects of convective heat flow have been\nmeasured at high intensities. Quantum dots have higher nonlinear refraction as\ncompared to the corresponding nanosheet samples, presumably due to reduced\ndimensionality. The effective values of nonlinear refractive index, estimated\nhere for near-resonant excitations, exceed those reported in the literature for\norganic-inorganic hybrid perovskites in the nonresonant excitation regime, by\nseveral orders of magnitude.",
        "positive": "Light-induced Dzyaloshinskii-Moriya interactions in antiferromagnetic\n  metals: The Dzyaloshinskii-Moriya (DM) interaction plays an essential role in novel\ntopological spintronics, and the ability to control this chiral interaction is\nof key importance. Developing a general microscopic framework to compute\nnonequilibrium DM interactions, we theoretically show that the ac electric\nfield component of a laser pulse induces nonequilibrium static DM interactions\nin an antiferromagnetic (AFM) system in the presence of relativistic spin-orbit\ncoupling. These nonequilibrium DM interactions might even be anisotropic\ndepending on the direction of magnetic moments and the laser pulse\npolarization. We further show that intense polarized laser pulses can in\nprinciple generate both classes of DM interactions, i.e., bulk-type and\ninterfacial-type, in a magnetic system even though the crystal symmetry\nprohibits one of them in equilibrium. Our results reveal another aspect of rich\nbehavior of periodically driven spin systems and the far-from-equilibrium\nmagnetic systems."
    },
    {
        "anchor": "Magnetic bit stability: Competition between domain-wall and monodomain\n  switching: We numerically study the thermal stability properties of computer memory\nstorage realized by a magnetic ellipse. In the case of practical magnetic\nrandom-access memory devices, the bit can form a spin texture during switching\nevents. To study the energy barrier for thermally-induced switching, we develop\na variational procedure to force the bit to traverse a smooth path through\nconfiguration space between the points of stability. We identify textured\nconfigurations realizing domain-wall propagation, which may have an energy\nbarrier less than that of the corresponding monodomain model. We contrast the\nemergence of such micromagnetic effects in thermal versus field-induced\nswitching.",
        "positive": "Relaxation dynamics and dissipative phase transition in quantum\n  oscillators with period tripling: Period tripling in driven quantum oscillators reveals unique features absent\nfor linear and parametric drive, but generic for all higher-order resonances.\nHere, we focus at zero temperature on the relaxation dynamics towards a\nstationary state starting initially from a domain around a classical fixed\npoint in phase space. Beyond a certain threshold for the driving strength, the\nlong-time dynamics is governed by a single time constant that sets the rate for\nswitching between different states with broken time translation symmetry. By\nanalyzing the lowest eigenvalues of the corresponding time evolution generator\nfor the dissipative dynamics, we find that near the threshold the gap between\nthese eigenvalues nearly closes. The closing becomes complete for a vanishing\nquantum parameter. We demonstrate that this behavior, reminiscent of a quantum\nphase transition, is associated with a transition from a stationary state which\nis localized in phase space to a delocalized one. We further show, that\nswitching between domains of classical fixed points happens via quantum\nactivation, however, with rates that differ from those obtained by a standard\nsemiclassical treatment. As period tripling has been explored with\nsuperconducting circuits mainly in the quasi-classical regime recently, our\nfindings may trigger new activities towards the deep quantum realm."
    },
    {
        "anchor": "Resistance noise in spin valves: Fluctuations of the magnetization in spin valves are shown to cause\nresistance noise that strongly depends on the magnetic configuration. Due to\nthe applied external field and the dynamic exchange interaction through the\nnormal metal spacer, the electrical noise level of the antiparallel\nconfiguration can exceed that of the parallel one by an order of magnitude, in\nagreement with recent experimental results.",
        "positive": "Opening and reversible control of a wide energy gap in uniform monolayer\n  graphene: For graphene to be used in semiconductor applications, a wide energy gap of\nat least 0.5 eV at the Dirac energy must be opened without the introduction of\natomic defects. However, such a wide energy gap has not been realized in\ngraphene, except in the cases of narrow, chemically terminated graphene\nnanostructures with inevitable edge defects. Here, we demonstrated that a wide\nenergy gap of 0.74 eV, which is larger than that of germanium, could be opened\nin uniform monolayer graphene without the introduction of atomic defects into\ngraphene. The wide energy gap was opened through the adsorption of\nself-assembled twisted sodium nanostrips. Furthermore, the energy gap was\nreversibly controllable through the alternate adsorption of sodium and oxygen.\nThe opening of such a wide energy gap with minimal degradation of mobility\ncould improve the applicability of graphene in semiconductor devices, which\nwould result in a major advancement in graphene technology."
    },
    {
        "anchor": "Charge and spin Hall effect in spin chiral ferromagnetic graphene: We predict a specific type of charge Hall effect in undoped ferromagnetic\ngraphene that is generated by the spin Hall mechanism in the absence of an\nexternal magnetic field. The essential feature is the so-called spin chiral\nconfiguration of the spin subbands in such a magnetic material where carriers\nwith opposite spin direction are of different type of electron-like or\nhole-like. Within the semiclassical theory of spin-orbital dynamics of\nelectrons, we obtain that a longitudinal electric field can produce a\nspin-orbit transverse current of pure charge with no polarization of the spin\nand the valley.",
        "positive": "Proposal for a local heating driven spin current generator: We propose a two-terminal spin-orbit interferometer with a hot molecule\ninserted in one of its arms to generate pure spin currents. Local heating is\nachieved by coupling the vibrational modes of the molecule to a third\n(phononic) reservoir. We show that this spin calorimetric effect is due to the\ncombined influence of spin-dependent wave interference and inelastic\nscattering. Remarkably, the device converts heat flow into spin-polarized\ncurrent even without applying any voltage or temperature difference to the\nelectronic terminals."
    },
    {
        "anchor": "Superlattice Based on Graphene on a Strip Substrate: A graphene-based superlattice formed due to the periodic modulation of the\nband gap has been investigated. Such a modulation is possible in graphene\ndeposited on a strip substrate made of silicon oxide and hexagonal boron\nnitride. The advantages and some possible problems in the superlattice under\nconsideration are discussed. A model describing such a superlattice is proposed\nand the dispersion relation between the energy and momentum of carriers has\nbeen obtained using the transfer matrix method within this model.",
        "positive": "Investigating microwave loss of SiGe using superconducting transmon\n  qubits: Silicon-Germanium (SiGe) is a material that possesses a multitude of\napplications ranging from transistors to eletro-optical modulators and quantum\ndots. The diverse properties of SiGe also make it attractive to implementations\ninvolving superconducting quantum computing. Here we demonstrate the\nfabrication of transmon quantum bits on SiGe layers and investigate the\nmicrowave loss properties of SiGe at cryogenic temperatures and single photon\nmicrowave powers. We find relaxation times of up to 100 $\\mu$s, corresponding\nto a quality factor Q above 4 M for large pad transmons. The high Q values\nobtained indicate that the SiGe/Si heterostructure is compatible with state of\nthe art performance of superconducting quantum circuits."
    },
    {
        "anchor": "The nature of domain walls in ultrathin ferromagnets revealed by\n  scanning nanomagnetometry: The recent observation of current-induced domain wall (DW) motion with large\nvelocity in ultrathin magnetic wires has opened new opportunities for\nspintronic devices. However, there is still no consensus on the underlying\nmechanisms of DW motion. Key to this debate is the DW structure, which can be\nof Bloch or N\\'eel type, and dramatically affects the efficiency of the\ndifferent proposed mechanisms. To date, most experiments aiming to address this\nquestion have relied on deducing the DW structure and chirality from its motion\nunder additional in-plane applied fields, which is indirect and involves strong\nassumptions on its dynamics. Here we introduce a general method enabling\ndirect, in situ, determination of the DW structure in ultrathin ferromagnets.\nIt relies on local measurements of the stray field distribution above the DW\nusing a scanning nanomagnetometer based on the Nitrogen-Vacancy defect in\ndiamond. We first apply the method to a Ta/Co40Fe40B20(1 nm)/MgO magnetic wire\nand find clear signature of pure Bloch DWs. In contrast, we observe left-handed\nN\\'eel DWs in a Pt/Co(0.6 nm)/AlOx wire, providing direct evidence for the\npresence of a sizable Dzyaloshinskii-Moriya interaction (DMI) at the Pt/Co\ninterface. This method offers a new path for exploring interfacial DMI in\nultrathin ferromagnets and elucidating the physics of DW motion under current.",
        "positive": "Inhomogeneous States in a Small Magnetic Disk with Single-Ion Surface\n  Anisotropy: We investigate analytically and numerically the ground and metastable states\nfor easy-plane Heisenberg magnets with single-ion surface anisotropy and disk\ngeometry. The configurations with two half-vortices at the opposite points of\nthe border are shown to be preferable for strong anisotropy. We propose a\nsimple analytical description of the spin configurations for all values of a\nsurface anisotropy. The effects of lattice pinning leads to appearance of a set\nof metastable configurations."
    },
    {
        "anchor": "Acoustoelectric current for composite fermions: The acoustelectric current for composite fermions in a two-dimensional\nelectron gas (2DEG) close to the half-filled Landau level is calculated in the\nrandom phase approximation. The Boltzmann equation is used to find the\nnonequilibrium distribution of composite fermions to second order in the\nacoustic field.It is shown that the oscillating Chern-Simons field created by\nthe induced density fluctuations in the 2DEG is important for the\nacoustoelectric current. This leads to a violation of the Weinreich relation\nbetween the acoustoelectric current and acoustic intensity. The deviations from\nthe Weinreich relation can be detected by measuring the angle between the\nlongitudinal and the Hall components of the acoustoelectric current. This\ndeparture from the Weinreich relation gives additional information on the\nproperties of the compostite fermion fluid.",
        "positive": "Evidence for a Goldstone Mode in a Double Layer Quantum Hall System: The tunneling conductance between two parallel 2D electron systems has been\nmeasured in a regime of strong interlayer Coulomb correlations. At total Landau\nlevel filling $\\nu_T=1$ the tunnel spectrum changes qualitatively when the\nboundary separating the compressible phase from the ferromagnetic quantized\nHall state is crossed. A huge resonant enhancement replaces the strongly\nsuppressed equilibrium tunneling characteristic of weakly coupled layers. The\npossible relationship of this enhancement to the Goldstone mode of the broken\nsymmetry ground state is discussed."
    },
    {
        "anchor": "Interplay between strain and size quantization in a class of topological\n  insulators based on inverted-band semiconductors: We consider surface states in semiconductors with inverted-band structures,\nsuch as $\\alpha$-Sn and HgTe. The main interest is the interplay of the effect\nof a strain of an arbitrary sign and that of the sample finite size. We clarify\nthe origin of various transitions which happen at a given strain with the\nchange of the sample thickness, in particular the transition between the Dirac\nsemimetal and quasi-3D (quantized) topological insulator. We compare our\nresults with the ones recently published in the literature.\n  For the k-p Kane model we derive effective boundary conditions in the case\nwhen the direct band materials form high barriers for the carriers of the inner\ninverted-band semiconductor (for example, CdTe/HgTe/CdTe and\nCdTe/$\\alpha$-Sn/CdTe cases). We show that in this case the BCs have an\nuniversal and simple form which does not depend on the order of different\nnon-commuting operators in the Hamiltonian. Even in the limit of very high\nbarriers the BCs do not reduce to the trivial zero form, but contain the\ninformation about the asymmetry of the offsets in the conduction and valence\nbands. These boundary conditions allow to investigate the realistic case of\nfinite mass of the heavy hole band, and to compare the results obtained within\nthe Kane and the Luttinger models.",
        "positive": "Analysis of a SU(4) generalization of Halperin's wave function as an\n  approach towards a SU(4) fractional quantum Hall effect in graphene sheets: Inspired by the four-fold spin-valley symmetry of relativistic electrons in\ngraphene, we investigate a possible SU(4) fractional quantum Hall effect, which\nmay also arise in bilayer semiconductor quantum Hall systems with small Zeeman\ngap. SU(4) generalizations of Halperin's wave functions [Helv. Phys. Acta 56,\n75 (1983)], which may break differently the original SU(4) symmetry, are\nstudied analytically and compared, at nu=2/3, to exact-diagonalization studies."
    },
    {
        "anchor": "Tunable dipolar magnetism in high-spin molecular clusters: We report on the Fe17 high-spin molecular cluster and show that this system\nis an exemplification of nanostructured dipolar magnetism. Each Fe17 molecule,\nwith spin S=35/2 and axial anisotropy as small as D=-0.02K, is the magnetic\nunit that can be chemically arranged in different packing crystals whilst\npreserving both spin ground-state and anisotropy. For every configuration,\nmolecular spins are correlated only by dipolar interactions. The ensuing\ninterplay between dipolar energy and anisotropy gives rise to macroscopic\nbehaviors ranging from superparamagnetism to long-range magnetic order at\ntemperatures below 1K.",
        "positive": "Anomalous D'yakonov-Perel' spin relaxation in InAs (110) quantum wells\n  under strong magnetic field: role of Hartree-Fock self-energy: We investigate the influence of the Hartree-Fock self-energy, acting as an\neffective magnetic field, on the anomalous D'yakonov-Perel' spin relaxation in\nInAs (110) quantum wells when the magnetic field in the Voigt configuration is\nmuch stronger than the spin-orbit-coupled field. The transverse and\nlongitudinal spin relaxations are discussed both analytically and numerically.\nFor the transverse configuration, it is found that the spin relaxation is very\nsensitive to the Hartree-Fock effective magnetic field, which is very different\nfrom the conventional D'yakonov-Perel' spin relaxation. Even an extremely small\nspin polarization ($P=0.1\\%$) can significantly influence the behavior of the\nspin relaxation. It is further revealed that this comes from the {\\em unique}\nform of the effective inhomogeneous broadening, originated from the mutually\nperpendicular spin-orbit-coupled field and strong magnetic field. It is shown\nthat this effective inhomogeneous broadening is very small and hence very\nsensitive to the Hartree-Fock field. Moreover, we further find that in the spin\npolarization dependence, the transverse spin relaxation time decreases with the\nincrease of the spin polarization in the intermediate spin polarization regime,\nwhich is also very different from the conventional situation, where the spin\nrelaxation is always suppressed by the Hartree-Fock field. It is revealed that\nthis {\\em opposite} trends come from the additional spin relaxation channel\ninduced by the HF field. For the longitudinal configuration, we find that the\nspin relaxation can be either suppressed or enhanced by the Hartree-Fock field\nif the spin polarization is parallel or antiparallel to the magnetic field."
    },
    {
        "anchor": "Theory of inertial spin dynamics in anisotropic ferromagnets: Recent experimental observation of inertial spin dynamics calls upon holistic\nreevaluation of the theoretical framework of magnetic resonance in\nferromagnets. Here, we derive the secular equation of an inertial spin system\nin analogy to the ubiquitous Smit-Beljers formalism. We find that the frequency\nof precessional ferromagnetic resonances is decreased as compared to\nnon-inertial case. We also find that the frequency of nutational resonances is\ngenerally increased due to the presence of magnetic anisotropy and applied\nmagnetic field. We obtain exact solutions of the secular equation and\napproximations that employ the terminology of non-inertial theory and thus\nallow for convenient estimates of the inertial effects.",
        "positive": "Hybridization and anisotropy in the exchange interaction in 3D Dirac\n  semimetals: We study the Ruderman-Kittel-Kasuya-Yosida interaction in 3D Dirac\nsemimetals. Using retarded Green's functions in real space, we obtain and\nanalyze asymptotic expressions for the interaction, with magnetic impurities at\ndifferent distances and relative angle with respect to high symmetry directions\non the lattice. We show that the Fermi velocity anisotropy in these materials\nproduces a strong renormalization of the magnitude of the interaction, as well\nas a correction to the frequency of oscillation in real space. Hybridization of\nthe impurities to different conduction electron orbitals are shown to result in\ninteresting anisotropic spin-spin interactions which can generate spiral spin\nstructures in doped samples."
    },
    {
        "anchor": "Topological nodal line semimetals with and without spin-orbital coupling: We theoretically study three-dimensional topological semimetals (TSMs) with\nnodal lines protected by crystalline symmetries. Compared with TSMs with point\nnodes, e.g., Weyl semimetals and Dirac semimetals, where the conduction and the\nvalence bands touch at discrete points, in these new TSMs the two bands cross\nat closed lines in the Brillouin zone. We propose two new classes of symmetry\nprotected nodal lines in the absence and in the presence of spin-orbital\ncoupling (SOC), respectively. In the former, we discuss nodal lines that are\nprotected by the combination of inversion symmetry and time-reversal symmetry;\nyet unlike any previously studied nodal lines in the same symmetry class, each\nnodal line has a $Z_2$ monopole charge and can only be created (annihilated) in\npairs. In the second class, with SOC, we show that a nonsymmorphic symmetry\n(screw axis) protects a four-band crossing nodal line in systems having both\ninversion and time-reversal symmetries.",
        "positive": "Superconducting Circuits for Quantum Simulation of Dynamical Gauge\n  Fields: We describe a superconducting-circuit lattice design for the implementation\nand simulation of dynamical lattice gauge theories. We illustrate our proposal\nby analyzing a one-dimensional U(1) quantum-link model, where superconducting\nqubits play the role of matter fields on the lattice sites and the gauge fields\nare represented by two coupled microwave resonators on each link between\nneighboring sites. A detailed analysis of a minimal experimental protocol for\nprobing the physics related to string breaking effects shows that despite the\npresence of decoherence in these systems, distinctive phenomena from\ncondensed-matter and high-energy physics can be visualized with\nstate-of-the-art technology in small superconducting-circuit arrays."
    },
    {
        "anchor": "A new electromagnetic mode in graphene: A new, weakly damped, {\\em transverse} electromagnetic mode is predicted in\ngraphene. The mode frequency $\\omega$ lies in the window\n$1.667<\\hbar\\omega/\\mu<2$, where $\\mu$ is the chemical potential, and can be\ntuned from radiowaves to the infrared by changing the density of charge\ncarriers through a gate voltage.",
        "positive": "Direct observation of a gate tunable band-gap in electrical transport in\n  ABC-trilayer graphene: Few layer graphene systems such as Bernal stacked bilayer and rhombohedral\n(ABC-) stacked trilayer offer the unique possibility to open an electric field\ntunable energy gap. To date, this energy gap has been experimentally confirmed\nin optical spectroscopy. Here we report the first direct observation of the\nelectric field tunable energy gap in electronic transport experiments on doubly\ngated suspended ABC-trilayer graphene. From a systematic study of the\nnon-linearities in current \\textit{versus} voltage characteristics and the\ntemperature dependence of the conductivity we demonstrate that thermally\nactivated transport over the energy-gap dominates the electrical response of\nthese transistors. The estimated values for energy gap from the temperature\ndependence and from the current voltage characteristics follow the\ntheoretically expected electric field dependence with critical exponent $3/2$.\nThese experiments indicate that high quality few-layer graphene are suitable\ncandidates for exploring novel tunable THz light sources and detectors."
    },
    {
        "anchor": "Polariton lasing and energy-degenerate parametric scattering in\n  non-resonantly driven coupled planar microcavities: Multi-level exciton-polariton systems offer an attractive platform for\nstudies of non-linear optical phenomena. However, studies of such consequential\nnon-linear phenomena as polariton condensation and lasing in planar\nmicrocavities have so far been limited to two-level systems, where the\ncondensation takes place in the lowest attainable state. Here, we report\nnon-equilibrium Bose-Einstein condensation of exciton-polaritons and low\nthreshold, dual-wavelength polariton lasing in vertically coupled, double\nplanar microcavities. Moreover, we find that the presence of the non-resonantly\ndriven condensate triggers interbranch exciton-polariton transfer in the form\nof energy-degenerate parametric scattering. Such an effect has so far been\nobserved only under excitation that is strictly resonant in terms of the energy\nand incidence angle. We describe theoretically our time-integrated and\ntime-resolved photoluminescence investigations by a set of rate equations\ninvolving an open-dissipative Gross-Pitaevskii equation. Our platform's\ninherent tunability is promising for construction of planar lattices, enabling\nthree-dimensional polariton hopping and realization of photonic devices, such\nas two-qubit polariton-based logic gates.",
        "positive": "Skyrmions in square-lattice antiferromagnets: The ground states of square lattice two-dimensional antiferromagnets with\nanisotropy in an external magnetic field are determined using Monte Carlo\nsimulations and compared to theoretical analysis. We find a new phase in\nbetween the spin-flop and spiral phase that shows strong similarity to\nskyrmions in ferromagnetic thin films. We show that this phase arises as a\nresult of the competition between Zeeman and Dzyaloshinskii-Moriya interaction\nenergies of the magnetic system. Moreover, we find that isolated\n(anti-)skyrmions are stabilized in finite-sized systems, even at higher\ntemperatures. The existence of thermodynamically stable skyrmions in\nsquare-lattice antiferromagnets provides an appealing alternative over\nskyrmions in ferromagnets as data carriers."
    },
    {
        "anchor": "Coulomb effects on the transmittance of open quantum dots in a\n  tight-binding model: A quantum-mechanical calculation of conductance in an open quantum dot is\nperformed in the Landauer-B\\\"{u}ttiker formalism using a tight binding\nHamiltonian with direct Coulomb interaction. The charge distribution in the dot\nis calculated self-consistently as function of a gate potential, for various\ndot-leads couplings. The interaction is active only inside the dot, but not in\nthe leads, its strength being an input parameter. Our calculations are\ncomplementary to the master-equation approach, go beyond the \"orthodox theory\",\nand account for the size, tunneling, and interaction effects in quantum dots.",
        "positive": "Resonant Cooper Pair Tunneling: Quantum Noise and Measurement\n  Characteristics: We study the quantum charge noise and measurement properties of the double\nCooper pair resonance point in a superconducting single-electron transistor\n(SSET) coupled to a Josephson charge qubit. Using a density matrix approach for\nthe coupled system, we obtain a full description of the measurement\nback-action; for weak coupling, this is used to extract the quantum charge\nnoise. Unlike the case of a non-superconducting SET, the back-action here can\ninduce population inversion in the qubit. We find that the Cooper pair\nresonance process allows for a much better measurement than a similar\nnon-superconducting SET, and can approach the quantum limit of efficiency."
    },
    {
        "anchor": "Wetting and energetics in nanoparticle etching of graphene: Molten metallic nanoparticles have recently been used to construct graphene\nnanostructures with crystallographic edges. The mechanism by which this\nhappens, however, remains unclear. Here, we present a simple model that\nexplains how a droplet can etch graphene. Two factors possibly contribute to\nthis process: a difference between the equilibrium wettability of graphene and\nthe substrate that supports it, or the large surface energy associated with the\ngraphene edge. We calculate the etching velocities due to either of these\nfactors and make testable predictions for evaluating the significance of each\nin graphene etching. This model is general and can be applied to other\nmaterials systems as well. As an example, we show how our model can be used to\nextend a current theory of droplet motion on binary semiconductor surfaces.",
        "positive": "Semi-classical approximation for the second harmonic generation in\n  nanoparticles: Second harmonic generation by spherical nanoparticles is a non-local optical\nprocess that can also be viewed as the result of the non-linear response of the\nthin interface layer. The classical electrodynamic description, based e.g. on\nthe non-linear Mie theory, entails the knowledge of the dielectric function and\nthe surface non-linear optical susceptibility, both quantities are usually\nassumed to be predetermined, for instance from experiment. We propose here an\napproach based on the semi-classical approximation for the quantum\nsum-over-states expression that allows to capture the second-order optical\nprocess from first principles. A key input is the electronic density, which can\nbe obtained from effective single particle approaches such as the\ndensity-functional theory in the local density implementation. We show that the\nresulting integral equations can be solved very efficiently rendering thus the\ntreatment of macroscopic systems. As an illustration we present numerical\nresults for the magic Na2869 cluster."
    },
    {
        "anchor": "Conductance oscillations of a spin-orbit stripe with polarized contacts: We investigate the linear conductance of a stripe of spin-orbit interaction\nin a 2D electron gas; that is, a 2D region of length $\\ell$ along the transport\ndirection and infinite in the transverse one in which a spin-orbit interaction\nof Rashba type is present. Polarization in the contacts is described by means\nof Zeeman fields. Our model predicts two types of conductance oscillations:\nRamsauer oscillations in the minority spin transmission, when both spins can\npropagate, and Fano oscillations when only one spin propagates. The latter are\ndue to the spin-orbit coupling with quasibound states of the non propagating\nspin. In the case of polarized contacts in antiparallel configuration Fano-like\noscillations of the conductance are still made possible by the spin orbit\ncoupling, even though no spin component is bound by the contacts. To describe\nthese behaviors we propose a simplified model based on an ansatz wave function.\nIn general, we find that the contribution for vanishing transverse momentum\ndominates and defines the conductance oscillations. Regarding the oscillations\nwith Rashba coupling intensity, our model confirms the spin transistor\nbehavior, but only for high degrees of polarization. Including a position\ndependent effective mass yields additional oscillations due to the mass jumps\nat the interfaces.",
        "positive": "Magnetic superconfinement of Dirac fermions zero-energy modes in bilayer\n  graphene quantum dots: We show that in bilayer graphene it is possible to achieve a very restrictive\nconfinement of the massless Dirac fermions zero-modes by using inhomogeneous\nmagnetic fields. Specifically, we show that, using a suitable nonuniform\nmagnetic fields, the wave function may be restricted to a specific region of\nthe space, being forbidden all transmission probability to the contiguous\nregions. This allows to construct mesoscopic structures in bilayer graphene by\nmagnetic fields configurations."
    },
    {
        "anchor": "Spin-polarized transport in a lateral two-dimensional diluted magnetic\n  semiconductor electron gas: The transport property of a lateral two-dimensional diluted magnetic\nsemiconductor electron gas under a spatially periodic magnetic field is\ninvestigated theoretically. We find that the electron Fermi velocity along the\nmodulation direction is highly spin-dependent even if the spin polarization of\nthe carrier population is negligibly small. It turns out that this\nspin-polarized Fermi velocity alone can lead to a strong spin polarization of\nthe current, which is still robust against the energy broadening effect induced\nby the impurity scattering.",
        "positive": "Charged impurity scattering in two-dimensional materials with\n  ring-shaped valence bands: GaS, GaSe, InS, and InSe: The singular density of states and the two Fermi wavevectors resulting from a\nring-shaped or \"Mexican hat\" valence band give rise to unique trends in the\ncharged impurity scattering rates and charged impurity limited mobilities. Ring\nshaped valence bands are common features of many monolayer and few-layer\ntwo-dimensional materials including the III-VI materials GaS, GaSe, InS, and\nInSe. The wavevector dependence of the screening, calculated within the random\nphase approximation, is so strong that it is the dominant factor determining\nthe overall trends of the scattering rates and mobilities with respect to\ntemperature and hole density. Charged impurities placed on the substrate and in\nthe 2D channel are considered. The different wavevector dependencies of the\nbare Coulomb potentials alter the temperature dependence of the mobilities.\nMoving the charged impurities 5 $\\AA$ from the center of the channel to the\nsubstrate increases the mobility by an order of magnitude."
    },
    {
        "anchor": "Cooling a magnetic resonance force microscope via the dynamical\n  back-action of nuclear spins: We analyze the back-action influence of nuclear spins on the motion of the\ncantilever of a magnetic force resonance microscope. We calculate the\ncontribution of nuclear spins to the damping and frequency shift of the\ncantilever. We show that, at the Rabi frequency, the energy exchange between\nthe cantilever and the spin system cools or heats the cantilever depending on\nthe sign of the high-frequency detuning. We also show that the spin noise leads\nto a significant damping of the cantilever motion.",
        "positive": "Free carrier absorption in quantum cascade structures: We show that the free carrier absorption in Quantum Cascade Lasers is very\nsmall and radically different from the classical Drude result on account of the\northogonality between the direction of the carrier free motion and the electric\nfield of the laser emission. A quantum mechanical calculation of the free\ncarrier absorption and inter-subband oblique absorption induced by interface\ndefects, coulombic impurities and optical phonon absorption/emission is\npresented for QCL's with a double quantum well design. The interaction between\nthe electrons and the optical phonons dominates at room temperature."
    },
    {
        "anchor": "Subradiant hybrid states in the open 3D Anderson-Dicke model: Anderson localization is a paradigmatic coherence effect in disordered\nsystems, often analyzed in the absence of dissipation. Here we consider the\ncase of coherent dissipation, occurring for open system with coupling to a\ncommon decay channel. This dissipation induces cooperative Dicke super- and\nsubradiance and an effective long range hopping, expected to destroy Anderson\nlocalization. We are thus in presence of two competing effects, i.e\nlocalization driven by disorder and delocalization driven by dissipative\nopening. Here we demonstrate the existence of a {\\it subradiant hybrid regime},\nemerging from the interplay of opening and disorder, in which subradiant states\nare {hybrid with both features of localized and extended states}, while\nsuperradiant states are extended. We also provide analytical predictions for\nthis regime, confirmed by numerical simulations.",
        "positive": "Detection of a persistent-current qubit by resonant activation: We present the implementation of a new scheme to detect the quantum state of\na persistent-current qubit. It relies on the dependency of the measuring\nSuperconducting Quantum Interference Device (SQUID) plasma frequency on the\nqubit state, which we detect by resonant activation. With a measurement pulse\nof only 5ns, we observed Rabi oscillations with high visibility (65%)."
    },
    {
        "anchor": "Electron phonon coupling in ultrathin Pb films on Si(111): Where the\n  heck is the energy?: In this work, we study the heat transfer from electron to phonon system\nwithin a five monolayer thin epitaxial Pb film on Si(111) upon fs-laser\nexcitation. The response of the electron system is determined using\ntime-resolved photoelectron spectroscopy while the lattice excitation is\nmeasured by means of the Debye-Waller effect in time-resolved reflection\nhigh-energy electron diffraction. The electrons lose their heat within 0.5 ps\nwhile the lattice temperature rises slowly in 3.5 to 8 ps, leaving a gap of 3-7\nps. We propose that the hidden energy is transiently stored in high-frequency\nphonon modes for which diffraction is insensitive and which are excited in 0.5\nps. Within a three-temperature model we use three heat baths, namely electrons,\nhigh-frequency and low-frequency phonon modes to simulate the observations. The\nexcitation of low-frequency acoustic phonons, i.e., thermalization of the\nlattice is facilitated through anharmonic phonon-phonon interaction.",
        "positive": "A versatile fabrication method for cluster superlattices: On the graphene moire on Ir(111) a variety of highly perfect cluster\nsuperlattices can be grown as shown is for Ir, Pt, W, and Re. Even materials\nthat do not form cluster superlattices upon room temperature deposition may be\ngrown into such by low temperature deposition or the application of cluster\nseeding through Ir as shown for Au, AuIr, FeIr. Criteria for the suitability of\na material to form a superlattice are given and largely confirmed. It is proven\nthat at least Pt and Ir even form epitaxial cluster superlattices. The\ntemperature stability of the cluster superlattices is investigated and\nunderstood on the basis of positional fluctuations of the clusters around their\nsites of minimum potential energy. The binding sites of Ir, Pt, W and Re\ncluster superlattices are determined and the ability to cover samples\nmacroscopically with a variety of superlattices is demonstrated."
    },
    {
        "anchor": "Two-Channel Kondo Physics in a Majorana Island Coupled to a Josephson\n  Junction: We study a Majorana island coupled to a bulk superconductor via a Josephson\njunction and to multiple external normal leads. In the absence of the Josephson\ncoupling, the system displays a topological Kondo state, which had been largely\nstudied recently. However, we find that this state is unstable even to small\nJosephson coupling, which instead leads at low temperature $T$ to a new fixed\npoint. Most interesting is the case of three external leads, forming a minimal\nelectronic realization of the long sought two-channel Kondo effect. While the\n$T=0$ conductance corresponds to simple resonant Andreev reflection, the\nleading $T$ dependence forms an experimental fingerprint for non-Fermi liquid\nproperties.",
        "positive": "Magnetic neutron scattering from spherical nanoparticles with Neel\n  surface anisotropy: Analytical treatment: The magnetization profile and the related magnetic small-angle neutron\nscattering cross section of a single spherical nanoparticle with Neel surface\nanisotropy is analytically investigated. We employ a Hamiltonian that comprises\nthe isotropic exchange interaction, an external magnetic field, a uniaxial\nmagnetocrystalline anisotropy in the core of the particle, and the Neel\nanisotropy at the surface. Using a perturbation approach, the determination of\nthe magnetization profile can be reduced to a Helmholtz equation with Neumann\nboundary condition, whose solution is represented by an infinite series in\nterms of spherical harmonics and spherical Bessel functions. From the resulting\ninfinite series expansion, we analytically calculate the Fourier transform,\nwhich is algebraically related to the magnetic small-angle neutron scattering\ncross section. The approximate analytical solution is compared to the numerical\nsolution using the Landau-Lifshitz equation, which accounts for the full\nnonlinearity of the problem."
    },
    {
        "anchor": "Transverse rectification in density-modulated two-dimensional electron\n  gases: We demonstrate tunable transverse rectification in a density-modulated\ntwo-dimensional electron gas (2DEG). The density modulation is induced by two\nsurface gates, running in parallel along a narrow stripe of 2DEG. A transverse\nvoltage in the direction of the density modulation is observed, i.e.\nperpendicular to the applied source-drain voltage. The polarity of the\ntransverse voltage is independent of the polarity of the source-drain voltage,\ndemonstrating rectification in the device. We find that the transverse voltage\n$U_{y}$ depends quadratically on the applied source-drain voltage and\nnon-monotonically on the density modulation. The experimental results are\ndiscussed in the framework of a diffusion thermopower model.",
        "positive": "Orbital Origin of Intrinsic Planar Hall Effect: Recent experiments reported an antisymmetric planar Hall effect, where the\nHall current is odd in the in-plane magnetic field and scales linearly with\nboth electric and magnetic fields applied. Existing theories rely exclusively\non a spin origin, which requires spin-orbit coupling to take effect. Here, we\ndevelop a general theory for the intrinsic planar Hall effect (IPHE),\nhighlighting a previously unknown orbital mechanism and connecting it to a band\ngeometric quantity -- the anomalous orbital polarizability (AOP). Importantly,\nthe orbital mechanism does not request spin-orbit coupling, so sizable IPHE can\noccur and is dominated by orbital contribution in systems with weak spin-orbit\ncoupling. Combined with first-principles calculations, we demonstrate our\ntheory with quantitative evaluation for bulk materials $\\mathrm{TaSb_{2}}$,\n$\\mathrm{NbAs_{2}}$, and $\\mathrm{SrAs_{3}}$. We further show that AOP and its\nassociated orbital IPHE can be greatly enhanced at topological band crossings,\noffering a new way to probe topological materials."
    },
    {
        "anchor": "Many-body effects in suspended graphene probed through magneto-phonon\n  resonances: We make use of micro-magneto Raman scattering spectroscopy to probe\nmagneto-phonon resonances (MPR) in suspended mono- to penta-layer graphene. MPR\ncorrespond to avoided crossings between zone-center optical phonons (G-mode)\nand optically-active inter Landau level (LL) transitions and provide a tool to\nperform LL spectroscopy at a fixed energy ($\\approx 197~\\rm{meV}$) set by the\nG-mode phonon. Using a single-particle effective bilayer model, we readily\nextract the velocity parameter associated with each MPR. A single velocity\nparameter slightly above the bulk graphite value suffices to fit all MPR for\n$N\\geq2$ layer systems. In contrast, in monolayer graphene, we find that the\nvelocity parameter increases significantly from $(1.23\\pm 0.01) \\times\n10^6~\\mathrm{m.s^{-1}}$ up to $(1.45\\pm0.02) \\times 10^6~\\mathrm{m.s^{-1}}$ as\nthe first to third optically-active inter LL transition couple to the G-mode\nphonon. This result is understood as a signature of enhanced many-body effects\nin unscreened graphene.",
        "positive": "Rectification of electronic heat current by a hybrid thermal diode: We report the realization of an ultra-efficient low-temperature hybrid heat\ncurrent rectifier, thermal counterpart of the well-known electric diode. Our\ndesign is based on a tunnel junction between two different elements: a normal\nmetal and a superconducting island. Electronic heat current asymmetry in the\nstructure arises from large mismatch between the thermal properties of these\ntwo. We demonstrate experimentally temperature differences exceeding $60$ mK\nbetween the forward and reverse thermal bias configurations. Our device offers\na remarkably large heat rectification ratio up to $\\sim 140$ and allows its\nprompt implementation in true solid-state thermal nanocircuits and\ngeneral-purpose electronic applications requiring energy harvesting or thermal\nmanagement and isolation at the nanoscale."
    },
    {
        "anchor": "Energetic, structural and electronic features of Sn-, Ga-, O-based\n  defect complexes in cubic In2O3: Defect energy formation, lattice distortions and electronic structure of\ncubic In2O3 with Sn, Ga and O impurities were theoretically investigated using\ndensity functional theory. Different types of point defects, consisting of 1 to\n4 atoms of Sn, Ga and O in both substitutional and interstitial (structural\nvacancy) positions, were examined. It was demonstrated, that formation of\nsubstitutional Ga and Sn defects are spontaneous, while formation of\ninterstitial defects requires an activation energy. The donor-like behavior of\ninterstitial Ga defects with splitting of conduction band into two subbands\nwith light and heavy electrons, respectively, was revealed. Contrarily,\ninterstitial O defects demonstrate acceptor-like behavior with the formation of\nacceptor levels or subbands inside the band gap. The obtained results are\nimportant for an accurate description of transport phenomena in In2O3 with\nsubstitutional and interstitial defects.",
        "positive": "On exact singular wave functions for identical planar charged particles\n  in uniform perpendicular magnetic field: We discuss the occurence and properties of exact singular anyonic wave\nfunctions describing stationary states of two identical charged particles\nmoving on a plane and under the influence of a perpendicular uniform magnetic\nfield."
    },
    {
        "anchor": "Fast spin exchange between two distant quantum dots: The Heisenberg exchange interaction between neighboring quantum dots allows\nprecise voltage control over spin dynamics, due to the ability to precisely\ncontrol the overlap of orbital wavefunctions by gate electrodes. This allows\nthe study of fundamental electronic phenomena and finds applications in quantum\ninformation processing. Although spin-based quantum circuits based on\nshort-range exchange interactions are possible, the development of scalable,\nlonger-range coupling schemes constitutes a critical challenge within the\nspin-qubit community. Approaches based on capacitative coupling and\ncavity-mediated interactions effectively couple spin qubits to the charge\ndegree of freedom, making them susceptible to electrically-induced decoherence.\nThe alternative is to extend the range of the Heisenberg exchange interaction\nby means of a quantum mediator. Here, we show that a multielectron quantum dot\nwith 50-100 electrons serves as an excellent mediator, preserving speed and\ncoherence of the resulting spin-spin coupling while providing several\nfunctionalities that are of practical importance. These include speed (mediated\ntwo-qubit rates up to several gigahertz), distance (of order of a micrometer),\nvoltage control, possibility of sweet spot operation (reducing susceptibility\nto charge noise), and reversal of the interaction sign (useful for dynamical\ndecoupling from noise).",
        "positive": "Large Andreev bound state zero bias peaks in a weakly dissipative\n  environment: We study Andreev bound states in hybrid InAs-Al nanowire devices. The energy\nof these states can be tuned to zero by gate voltage or magnetic field,\nrevealing large zero bias peaks (ZBPs) near 2e^2/h in tunneling conductance.\nProbing these large ZBPs using a weakly dissipative lead reveals non-Fermi\nliquid temperature (T) dependence due to environmental Coulomb blockade (ECB),\nan interaction effect from the lead acting on the nanowire junction. By\nincreasing T, these large ZBPs either show a height increase or a transition\nfrom split peaks to a ZBP, both deviate significantly from non-dissipative\ndevices where a Fermi-liquid T dependence is revealed. Our result demonstrates\nthe competing effect between ECB and thermal broadening on Andreev bound\nstates."
    },
    {
        "anchor": "Diffractive energy spreading and its semiclassical limit: We consider driven systems where the driving induces jumps in energy space:\n(1) particles pulsed by a step potential; (2) particles in a box with a moving\nwall; (3) particles in a ring driven by an electro-motive-force. In all these\ncases the route towards quantum-classical correspondence is highly non-trivial.\nSome insight is gained by observing that the dynamics in energy space, where\n$n$ is the level index, is essentially the same as that of Bloch electrons in a\ntight binding model, where $n$ is the site index. The mean level spacing is\nlike a constant electric field and the driving induces long range hopping\n1/(n-m).",
        "positive": "Hysteresis of nanocylinders with Dzyaloshinskii-Moriya interaction: The potential for application of magnetic skyrmions in high density storage\ndevices provides a strong drive to investigate and exploit their stability and\nmanipulability. Through a three-dimensional micromagnetic hysteresis study, we\ninvestigate the question of existence of skyrmions in cylindrical\nnanostructures of variable thickness. We quantify the applied field and\nthickness dependence of skyrmion states, and show that these states can be\naccessed through relevant practical hysteresis loop measurement protocols. As\nskyrmionic states have yet to be observed experimentally in confined\nhelimagnetic geometries, our work opens prospects for developing viable\nhysteresis process-based methodologies to access and observe skyrmionic states."
    },
    {
        "anchor": "Gate-defined Two-dimensional Hole and Electron Systems in an Undoped\n  InSb Quantum Well: Quantum transport measurements are performed in gate-defined, high-quality,\ntwo-dimensional hole and electron systems in an undoped InSb quantum well. For\nboth polarities, the carrier systems show tunable spin-orbit interaction as\nextracted from weak anti-localization measurements. The effective mass of InSb\nholes strongly increases with carrier density as determined from the\ntemperature dependence of Shubnikov-de Haas oscillations. Coincidence\nmeasurements in a tilted magnetic field are performed to estimate the spin\nsusceptibility of the InSb two-dimensional hole system. The g-factor of the\ntwo-dimensional hole system decreases rapidly with increasing carrier density.",
        "positive": "Spectrum of $\u03c0$-electrons in Graphene As a Macromolecule: We report the exact solution of spectral problem for a graphene sheet framed\nby two armchair- and two zigzag-shaped boundaries. The solution is found for\nthe $\\pi$ electron Hamiltonian and gives, in particular, a closed analytic\nexpression of edge-state energies in graphene. It is shown that the lower\nsymmetry of graphene, in comparison with $C_{6h}$ of 2D graphite, has a\nprofound effect on the graphene band structure. This and other obtained results\nhave far going implications for the understanding of graphene electronics. Some\nof them are briefly discussed."
    },
    {
        "anchor": "Experimental observation of topological exciton-polaritons in transition\n  metal dichalcogenide monolayers: The rise of quantum science and technologies motivates photonics research to\nseek new platforms with strong light-matter interactions to facilitate quantum\nbehaviors at moderate light intensities. One promising platform to reach such\nstrong light-matter interacting regimes is offered by polaritonic metasurfaces,\nwhich represent ultrathin artificial media structured on nano-scale and\ndesigned to support polaritons - half-light half-matter quasiparticles.\nTopological polaritons, or 'topolaritons', offer an ideal platform in this\ncontext, with unique properties stemming from topological phases of light\nstrongly coupled with matter. Here we explore polaritonic metasurfaces based on\n2D transition metal dichalcogenides (TMDs) supporting in-plane polarized\nexciton resonances as a promising platform for topological polaritonics. We\nenable a spin-Hall topolaritonic phase by strongly coupling valley polarized\nin-plane excitons in a TMD monolayer with a suitably engineered all-dielectric\ntopological photonic metasurface. We first show that the strong coupling\nbetween topological photonic bands supported by the metasurface and excitonic\nbands in MoSe2 yields an effective phase winding and transition to a\ntopolaritonic spin-Hall state. We then experimentally realize this phenomenon\nand confirm the presence of one-way spin-polarized edge topolaritons. Combined\nwith the valley polarization in a MoSe2 monolayer, the proposed system enables\na new approach to engage the photonic angular momentum and valley degree of\nfreedom in TMDs, offering a promising platform for photonic/solid-state\ninterfaces for valleytronics and spintronics.",
        "positive": "Resolved sidebands in a strain-coupled hybrid spin-oscillator system: We report on single electronic spins coupled to the motion of mechanical\nresonators by a novel mechanism based on crystal strain. Our device consists of\nsingle-crystalline diamond cantilevers with embedded Nitrogen-Vacancy center\nspins. Using optically detected electron spin resonance, we determine the\nunknown spin-strain coupling constants and demonstrate that our system resides\nwell within the resolved sideband regime. We realize coupling strengths\nexceeding ten MHz under mechanical driving and show that our system has the\npotential to reach strong coupling. Our novel hybrid system forms a resource\nfor future experiments on spin-based cantilever cooling and coherent\nspin-oscillator coupling."
    },
    {
        "anchor": "Self-biased current, magnetic interference response, and superconducting\n  vortices in tilted Weyl semimetals with disorder: We have generalized a quasiclassical model for Weyl semimetals with a tilted\nband in the presence of an externally applied magnetic field. This model is\napplicable to ballistic, moderately disordered, and samples containing a high\ndensity of nonmagnetic impurities. We employ this formalism and show that a\nself-biased supercurrent, creating a {\\phi}0-junction, can flow through a\ntriplet channel in Weyl semimetals. Furthermore, our results demonstrate that\nmultiple supercurrent reversals are accessible through varying junction\nthickness and parameters characterizing Weyl semimetals. We discuss the\ninfluence of different parameters on the Fraunhofer response of charge\nsupercurrent, and how these parameters are capable of shifting the locations of\nproximity-induced vortices in the triplet channel.",
        "positive": "Nonlinear Hall effect in Rashba systems with hexagonal warping: Rashba spin-orbit coupled systems are an important class of materials noted\nfor diverse fundamental and applied phenomena. Recently, the emergence of\nnon-linear Hall effect under conditions of time-reversal symmetry has been\ndiscovered in materials with broken inversion symmetry. In this work, we study\nthe second- and third-order Hall response in Rashba systems with hexagonal\nwarping. Starting with a low-energy model, we obtain the analytic expressions\nand discover the unique dipole profile in Rashba systems with hexagonal\nwarping. Furthermore, we extend the analysis using a realistic tight-binding\nmodel. Next, we predict the existence of a third-order Hall effect in these\nsystems, and calculate the Berry connection polarizability tensor analytically.\nWe also show how the model parameters affect the third-order conductivity. Our\npredictions can help in the experimental realization of Berry curvature\nmultipole physics in Rashba materials with hexagonal warping, and provide a new\nplatform for engineering the non-linear Hall effects."
    },
    {
        "anchor": "Chirality blockade of Andreev reflection in a magnetic Weyl semimetal: A Weyl semimetal with broken time-reversal symmetry has a minimum of two\nspecies of Weyl fermions, distinguished by their opposite chirality, in a pair\nof Weyl cones at opposite momenta $\\pm K$ that are displaced in the direction\nof the magnetization. Andreev reflection at the interface between a Weyl\nsemimetal in the normal state (N) and a superconductor (S) that pairs $\\pm K$\nmust involve a switch of chirality, otherwise it is blocked. We show that this\n\"chirality blockade\" suppresses the superconducting proximity effect when the\nmagnetization lies in the plane of the NS interface. A Zeeman field at the\ninterface can provide the necessary chirality switch and activate Andreev\nreflection.",
        "positive": "Excitation-induced transition to indirect band gaps in atomically thin\n  transition metal dichalcogenide semiconductors: Monolayers of transition metal dichalcogenides (TMDCs) exhibit an\nexceptionally strong Coulomb interaction between charge carriers due to the\ntwo-dimensional carrier confinement in connection with weak dielectric\nscreening. High densities of excited charge carriers in the various\nband-structure valleys cause strong many-body renormalizations that influence\nboth the electronic properties and the optical response of the material. We\ninvestigate electronic and optical properties of the typical monolayer TMDCs\nMoS$_2$, MoSe$_2$, WS$_2$ and WSe$_2$ in the presence of excited carriers by\nsolving semiconductor Bloch equations on the full Brillouin zone. With\nincreasing carrier density, we systematically find a reduction of the exciton\nbinding energies due to Coulomb screening and Pauli blocking. Together with\nexcitation-induced band-gap shrinkage this leads to redshifts of excitonic\nresonances up to the dissociation of excitons. As a central result, we predict\nfor all investigated monolayer TMDCs that the $\\Sigma$-valley shifts stronger\nthan the K-valley. Two of the materials undergo a transition from direct to\nindirect band gaps under carrier excitation similar to well-known\nstrain-induced effects. Our findings have strong implications for the filling\nof conduction-band valleys with excited carriers and are relevant to transport\nand optical applications as well as the emergence of phonon-driven\nsuperconductivity."
    },
    {
        "anchor": "Non-exponential relaxation and quantum tunnel splitting in molecular\n  magnet Fe8: Magnetic relaxation in molecular magnets under a sweeping field is studied by\ntaking into account local stray fields. It is found that the randomness of\nlocal stray field leads to a distribution of the relaxation rate which\nsubsequently makes the relaxation deviate from the exponential law as predicted\nby the Landau-Zener model such that the Landau-Zener method needs to be revised\nto deduce an exact tunneling splitting. The tunneling splitting and\ndistribution width of local stray fields are derived from the experimental data\nfor molecular magnets Fe8.",
        "positive": "Inhomogeneous nuclear spin polarization induced by helicity-modulated\n  optical excitation of fluorine-bound electron spins in ZnSe: Optically-induced nuclear spin polarization in a fluorine-doped ZnSe epilayer\nis studied by time-resolved Kerr rotation using resonant excitation of\ndonor-bound excitons. Excitation with helicity-modulated laser pulses results\nin a transverse nuclear spin polarization, which is detected as a change of the\nLarmor precession frequency of the donor-bound electron spins. The frequency\nshift in dependence on the transverse magnetic field exhibits a pronounced\ndispersion-like shape with resonances at the fields of nuclear magnetic\nresonance of the constituent zinc and selenium isotopes. It is studied as a\nfunction of external parameters, particularly of constant and radio frequency\nexternal magnetic fields. The width of the resonance and its shape indicate a\nstrong spatial inhomogeneity of the nuclear spin polarization in the vicinity\nof a fluorine donor. A mechanism of optically-induced nuclear spin polarization\nis suggested based on the concept of resonant nuclear spin cooling driven by\nthe inhomogeneous Knight field of the donor-bound electron."
    },
    {
        "anchor": "Photodoping-driven crossover in low-frequency noise in MoS2 transistors: Transition metal dichalcogenide field-effect transistors (FETs) have been\nactively explored for low-power electronics, light detection, and sensing.\nAlbeit promising, their performance is strongly limited by low-frequency noise\n(LFN). Here, we report on the study of LFN in MoS$_2$ FETs on SiO$_2$\nsubstrates in ambient conditions using photodoping. Using this external\nexcitation source allows us to access different non-equilibrium steady states\nand cross over different noise regimes. We observe a dependence of the noise\npower spectrum with the transient decay time window, approaching $1/f$-type\nwhen the system is closer to equilibrium, and identify a dependence of the LFN\nwith channel thickness. Monolayer/bilayer devices exhibit random telegraph\nnoise for insulating regimes and $1/f$-type Hooge mobility fluctuations (HMF)\nfor conductive regimes. Thicker devices exhibit mainly $1/f$-type carrier\nnumber fluctuations (CNF). In the latter, we observe a photodoping-induced\nchange from a near parabolic to a near linear dependence of the inverse $1/f$\nnoise amplitude above the threshold gate voltage. This change indicates a\ncrossover in the LFN mechanism from CNF to HMF. We demonstrate that the study\nof conductance and noise under photodoping is an effective tool to identify\ndominating carrier noise mechanisms in few-atomic-layer FETs for a wide range\nof doping regimes.",
        "positive": "A frequency-stabilized source of single photons from a solid-state qubit: Single quantum dots are solid-state emitters which mimic two-level atoms but\nwith a highly enhanced spontaneous emission rate. A single quantum dot is the\nbasis for a potentially excellent single photon source. One outstanding problem\nis that there is considerable noise in the emission frequency, making it very\ndifficult to couple the quantum dot to another quantum system. We solve this\nproblem here with a dynamic feedback technique that locks the quantum dot\nemission frequency to a reference. The incoherent scattering (resonance\nfluorescence) represents the single photon output whereas the coherent\nscattering (Rayleigh scattering) is used for the feedback control. The\nfluctuations in emission frequency are reduced to 20 MHz, just ~ 5% of the\nquantum dot optical linewidth, even over several hours. By eliminating the\n1/f-like noise, the relative fluctuations in resonance fluorescence intensity\nare reduced to ~ 10E-5 at low frequency. Under these conditions, the\nantibunching dip in the resonance fluorescence is described extremely well by\nthe two-level atom result. The technique represents a way of removing charge\nnoise from a quantum device."
    },
    {
        "anchor": "Interplay of fractional quantum Hall states and localization in quantum\n  point contacts: We investigate integer and fractional quantum Hall states in quantum point\ncontacts (QPCs) of different geometries, defined in AlGaAs/GaAs\nheterostructures employing different doping and screening techniques. We find\nthat, even in the highest mobility samples, interference and localization\nstrongly influence the transport properties. We propose microscopic models for\nthese effects, based on single- and many-electron physics. For integer quantum\nHall states, transport is modulated due to the self-consistent formation of\ncompressible regions of enhanced or reduced density in the incompressible\nregion of the constriction. In the fractional quantum Hall regime, we observe\nthe localization of fractionally charged quasi-particles in the constriction\nand an interplay of single- and many-electron physics. At low electron\ndensities and in comparatively weak magnetic fields, single-electron\ninterference dominates transport. Utilizing optimized growth and gating\ntechniques, the $\\nu$=5/2 state can be observed in a QPC, conserving the bulk\nproperties in an unprecedented quality. Our results might improve the\nunderstanding of the influence of localization on the transmission properties\nof QPCs, which is necessary for the interpretation of interference experiments\nemploying QPCs, especially at $\\nu$=5/2.",
        "positive": "Scaling Approach to the Phase Diagram of Quantum Hall Systems: We present a simple classification of the different liquid and solid phases\nof quantum Hall systems in the limit where the Coulomb interaction between the\nelectrons is significant, i.e. away from integral filling factors. This\nclassification, and a criterion for the validity of the mean-field\napproximation in the charge-density-wave phase, is based on scaling arguments\nconcerning the effective interaction potential of electrons restricted to an\narbitrary Landau level. Finite-temperature effects are investigated within the\nsame formalism, and a good agreement with recent experiments is obtained."
    },
    {
        "anchor": "Raman spectrum of Janus transition metal dichalcogenide monolayers WSSe\n  and MoSSe: Janus transition metal dichalcogenides (TMDs) lose the horizontal mirror\nsymmetry of ordinary TMDs, leading to the emergence of additional features,\nsuch as native piezoelectricity, Rashba effect, and enhanced catalytic\nactivity. While Raman spectroscopy is an essential nondestructive, phase- and\ncomposition-sensitive tool to monitor the synthesis of materials, a\ncomprehensive study of the Raman spectrum of Janus monolayers is still missing.\nHere, we discuss the Raman spectra of WSSe and MoSSe measured at room and\ncryogenic temperatures, near and off resonance. By combining\npolarization-resolved Raman data with calculations of the phonon dispersion and\nusing symmetry considerations, we identify the four first-order Raman modes and\nhigher-order two-phonon modes. Moreover, we observe defect-activated phonon\nprocesses, which provide a route toward a quantitative assessment of the defect\nconcentration and, thus, the crystal quality of the materials synthesized. Our\nwork establishes a solid background for future research on material synthesis,\nstudy, and application of Janus TMD monolayers.",
        "positive": "Bulk-boundary-defect correspondence at disclinations in\n  rotation-symmetric topological insulators and superconductors: We study a link between the ground-state topology and the topology of the\nlattice via the presence of anomalous states at disclinations -- topological\nlattice defects that violate a rotation symmetry only locally. We first show\nthe existence of anomalous disclination states, such as Majorana zero-modes or\nhelical electronic states, in second-order topological phases by means of\nVolterra processes. Using the framework of topological crystals to construct\n$d$-dimensional crystalline topological phases with rotation and translation\nsymmetry, we then identify all contributions to $(d-2)$-dimensional anomalous\ndisclination states from weak and first-order topological phases. We perform\nthis procedure for all Cartan symmetry classes of topological insulators and\nsuperconductors in two and three dimensions and determine whether the\ncorrespondence between bulk topology, boundary signatures, and disclination\nanomaly is unique."
    },
    {
        "anchor": "Three-particle Complexes in Two-Dimensional Semiconductors: We map the three-body problem in two dimensions onto one particle in a three\ndimensional potential treatable by a purposely-developed\nboundary-matching-matrix method. We evaluate binding energies of trions\n$X^{\\pm}$, excitons bound by a donor/acceptor charge $X^{D/A}$, and overcharged\nacceptors/donors in two-dimensional atomic crystals of transition metal\ndichalcogenides, where interaction between charges features logarithmic\nbehavior at intermediate distances. We find that dissociation energy of\n$X^{\\pm}$ is, typically, much larger than that of localised exciton complexes,\nso that trions are more resilient to heating, despite that their recombination\nline in optics is much less red-shifted from the exciton line, as compared to\n$X^{D/A}$",
        "positive": "Experimental realization of a Szilard engine with a single electron: The most succinct manifestation of the second law of thermodynamics is the\nlimitation the Landauer principle imposes on the amount of heat a Maxwell demon\n(MD) can convert into free energy per single bit of information obtained in a\nmeasurement. We suggest and experimentally realize a reversible electronic MD\nbased on a single-electron box operated as a Szilard engine, providing the\nfirst demonstration of this limitation: extraction of kT ln 2 of heat from the\nreservoir at temperature T per one bit of created information. The information\nis encoded in the position of an extra electron in the box."
    },
    {
        "anchor": "The effect of edge and impurities sites properties on their localized\n  states in semi-infinite zigzag edged 2D honeycomb graphene sheet: In this work, the tridiagonal method is used to distinguish between edges\nmodes and area modes to study the edge sites properties effect on edge\nlocalized states of semi-infinite zigzag 2D honeycomb graphene sheet. The\nresults show a realistic behavior for the dependance of edge localized states\nof zigzag graphene on the edge sites properties which explaining the\nexperimental results of measured local density of states at the edge of\ngraphene, while at the same time removing the inconsistence between the\nsemiconductor behavior found in the experimental data for fabricated GNRs and\nthe expected theoretical semi-metallic behavior calculated without considering\nthe edge properties effect on the edge localized states.",
        "positive": "Tunable Superconducting Phase Transition in Metal-Decorated Graphene\n  Sheets: Using typical experimental techniques it is difficult to separate the effects\nof carrier density and disorder on the superconducting transition in two\ndimensions. Using a simple fabrication procedure based on metal layer\ndewetting, we have produced graphene sheets decorated with a non-percolating\nnetwork of nanoscale tin clusters. These metal clusters both efficiently dope\nthe graphene substrate and induce long-range superconducting correlations. This\nallows us to study the superconducting transition at fixed disorder and\nvariable carrier concentration. We find that despite structural inhomogeneity\non mesoscopic length scales (10-100 nm), this material behaves electronically\nas a homogenous dirty superconductor. Our simple self-assembly method\nestablishes graphene as an ideal tunable substrate for studying induced\ntwo-dimensional electronic systems at fixed disorder and our technique can\nreadily be extended to other order parameters such as magnetism."
    },
    {
        "anchor": "Exciton spectrum in multi-shell hexagonal semiconductor nanotube: The theory of exciton spectrum in multi-shell hexagonal semiconductor\nnanotube is developed within the effective masses and rectangular potentials\napproximations using the method of effective potential. It is shown that the\nexciton binding energy for all states non-monotonously depends on the inner\nwire diameter, approaching several minimal and maximal magnitudes. The obtained\ntheoretical results explain well the experimental positions of luminescence\npeaks for GaAs/Al_{0.4}Ga_{0.6}As nanotubes.",
        "positive": "Curvature-mediated spin textures in magnetic multi-layered nanotubes: The scientific and technological exploration of artificially designed\nthree-dimensional magnetic nanostructures opens the path to exciting novel\nphysical phenomena, originating from the increased complexity in spin textures,\ntopology, and frustration in three dimensions. Theory predicts that the\nequilibrium magnetic ground state of two-dimensional systems which reflects the\ncompetition between symmetric (Heisenberg) and antisymmetric\n(Dzyaloshinskii-Moriya interaction (DMI)) exchange interaction is significantly\nmodified on curved surfaces when the radius of local curvature becomes\ncomparable to fundamental magnetic length scales. Here, we present an\nexperimental study of the spin texture in an 8 nm thin magnetic multilayer with\ngrowth-induced in-plane anisotropy and DMI deposited onto the curved surface of\na 1.8 {\\mu}m long non-magnetic carbon nanowire with a 67 nm radius. Using\nmagnetic soft x-ray tomography the three-dimensional spin configuration in this\nnanotube was retrieved with about 30nm spatial resolution. The transition\nbetween two vortex configurations on the two ends of the nanotube with opposite\ncirculation occurs through a domain wall that is aligned at an inclined angle\nrelative to the wire axis. Three-dimensional micromagnetic simulations support\nthe experimental observations and represent a visualization of the\ncurvature-mediated DMI. They also allow a quantitative estimate of the DMI\nvalue for the magnetic multilayered nanotube."
    },
    {
        "anchor": "Multiple Exciton Generation in Chiral Carbon Nanotubes: Density\n  Functional Theory Based Computation: We use Boltzmann transport equation (BE) to study time evolution of a\nphoto-excited state in a nanoparticle including phonon-mediated exciton\nrelaxation and the multiple exciton generation (MEG) processes, such as\nexciton-to-biexciton multiplication and biexciton-to-exciton recombination. BE\ncollision integrals are computed using Kadanoff-Baym-Keldysh many-body\nperturbation theory (MBPT) based on density functional theory (DFT)\nsimulations, including exciton effects. We compute internal quantum efficiency\n(QE), which is the number of excitons generated from an absorbed photon in the\ncourse of the relaxation. We apply this approach to chiral single-wall carbon\nnanotubes (SWCNTs), such as (6,2), and (6,5). We predict efficient MEG in the\n(6,2) and (6,5) SWCNTs within the solar spectrum range starting at the $2 E_g$\nenergy threshold and with QE reaching $\\sim 1.6$ at about $3 E_g,$ where $E_g$\nis the electronic gap.",
        "positive": "Direct equivalence between quantum phase transition phenomena in\n  radiation-matter and magnetic systems: scaling of entanglement: We show that the quantum phase transition arising in a standard\nradiation-matter model (Dicke model) belongs to the same universality class as\nthe infinitely-coordinated, transverse field XY model. The effective\nqubit-qubit exchange interaction is shown to be proportional to the square of\nthe qubit-radiation coupling. A universal finite-size scaling is derived for\nthe corresponding two-qubit entanglement (concurrence) and a size-consistent\neffective Hamiltonian is proposed for the qubit subsystem."
    },
    {
        "anchor": "Spectral Characteristics of the Microwave Emission by the Spin Hall\n  Nano-Oscillator: We utilized microwave spectroscopy to study the magnetization oscillations\nlocally induced in a Permalloy film by a pure spin current, which is generated\ndue to the spin Hall effect in an adjacent Pt layer. The oscillation frequency\nis lower than the ferromagnetic resonance of Permalloy, indicating that the\noscillation forms a self-localized nonpropagating spin-wave soliton. At\ncryogenic temperatures, the spectral characteristics are remarkably similar to\nthe traditional spin-torque nano-oscillators driven by spin-polarized currents.\nHowever, the linewidth of the oscillation increases exponentially with\ntemperature and an additional peak appears in the spectrum below the\nferromagnetic resonance, suggesting that the spectral characteristics are\ndetermined by interplay between two localized dynamical states.",
        "positive": "Effects of surface potentials on Goos-Haenchen and Imbert-Fedorov shifts\n  in Weyl semimetals: Weyl semimetals exhibit exotic transport responses, among which, recently\nGoos-Haenchen (GH) and Imbert-Fedorov (IF) effects have received a revived\nattention, which are, otherwise, well-studied phenomena in optical systems and\ncertain electronic systems. Besides the usual parametric dependence of the\nshifts inherited from the underlying Hamiltonian to describe the Weyl system\nand/or that induced by external controls, the IF shift further carries a\ntopological identity -- it depends on the chirality of the Weyl cones. A\nrealistic system of Weyl semimetal naturally accommodates surface potentials\ninduced by impurities present on its surface that could pose impediments to\nobserve clean transport signatures predicted in theoretical models. Classifying\nthese potentials, we study their effects on GH and IF shifts to provide useful\nguidance to future experiments that are tuned to the objective of\ncharacterizing Weyl semimetals and for a possible realisation of novel devices\nbased on these phenomena. A transfer matrix-based approach is invoked to study\nthe profile of Weyl wavefunctions across the interface which is hosting the\nimpurity potentials, revealing that such potentials can lead to several\ndiscerning effects which, in certain cases, extend even to nullifying the IF\nshift completely and giving rise to phenomenon like valley inversion."
    },
    {
        "anchor": "Anyonic Excitations in Fast Rotating Bose Gases: The role of anyonic excitations in fast rotating harmonically trapped Bose\ngases in a fractional Quantum Hall State is examined. Standard Chern-Simons\nanyons as well as \"non standard\" anyons obtained from a statistical interaction\nhaving Maxwell-Chern-Simons dynamics and suitable non minimal coupling to\nmatter are considered. Their respective ability to stabilize attractive Bose\ngases under fast rotation in the thermodynamical limit is studied. Stability\ncan be obtained for standard anyons while for non standard anyons, stability\nrequires that the range of the corresponding statistical interaction does not\nexceed the typical wavelength for the atoms.",
        "positive": "Large Anomalous Hall Effect in Topological Insulators Proximitized by\n  Collinear Antiferromagnets: CrSb is an attractive material for room-temperature antiferromagnetic\nspintronic applications because of its high N\\'{e}el temperature $\\sim$700 K\nand semi-metallic character. We study the magnetic properties of CrSb bilayers\non few-layer topological insulator thin films using \\emph{ab initio} density\nfunctional theory. We find that the intrinsic parts of the total anomalous Hall\nconductivities of the thin films are non-zero, and approximately quantized. The\nN\\'{e}el temperature of CrSb bilayers on few-layer topological insulator thin\nfilms is found to be approximately two times larger than that of an isolated\nCrSb thin film. Due to the low Fermi level density of states of CrSb, Hall\nquantization might be achievable by introducing disorder. CrSb bilayers on\ntopological insulator surfaces are therefore attractive candidates for\nhigh-temperature quantum anomalous Hall effects."
    },
    {
        "anchor": "Negative orbital Hall effect in Germanium: Our investigation reveals a groundbreaking discovery of a negative inverse\norbital Hall effect (IOHE) in Ge thin films. We employed the innovative orbital\npumping technique where spin-orbital coupled current is injected into Ge films\nusing YIG/Pt(2)/Ge($t_{Ge}$) and YIG/W(2)/Ge($t_{Ge}$) heterostructures.\nThrough comprehensive analysis, we observe significant reductions in the\nsignals generated by coherent (RF-driven) and incoherent (thermal-driven)\nspin-orbital pumping techniques. These reductions are attributed to the\npresence of a remarkable strong negative IOHE in Ge, showing its magnitude\ncomparable to the spin-to-charge signal in Pt. Our findings reveal that\nalthough the spin-to-charge conversion in Ge is negligible, the\norbital-to-charge conversion exhibits large magnitude. Our results are\ninnovative and pioneering in the investigation of negative IOHE by the\ninjection of spin-orbital currents.",
        "positive": "Supercurrents in chiral channels originate from upstream information\n  transfer: a theoretical prediction: It has been thought that the long chiral edge channels cannot support any\nsupercurrent between the superconducting electrodes. We show theoretically that\nthe supercurrent can be mediated by a non-local interaction that facilitates a\nlong-distance information transfer in the direction opposite to electron flow.\nWe compute the supercurrent for several interaction models, including that of\nan external circuit."
    },
    {
        "anchor": "The elusive memristor: properties of basic electrical circuits: We present a tutorial on the properties of the new ideal circuit element, a\nmemristor. By definition, a memristor M relates the charge q and the magnetic\nflux $\\phi$ in a circuit, and complements a resistor R, a capacitor C, and an\ninductor L as an ingredient of ideal electrical circuits. The properties of\nthese three elements and their circuits are a part of the standard curricula.\nThe existence of the memristor as the fourth ideal circuit element was\npredicted in 1971 based on symmetry arguments, but was clearly experimentally\ndemonstrated just this year. We present the properties of a single memristor,\nmemristors in series and parallel, as well as ideal memristor-capacitor (MC),\nmemristor-inductor (ML), and memristor-capacitor-inductor (MCL) circuits. We\nfind that the memristor has hysteretic current-voltage characteristics. We show\nthat the ideal MC (ML) circuit undergoes non-exponential charge (current) decay\nwith two time-scales, and that by switching the polarity of the capacitor, an\nideal MCL circuit can be tuned from overdamped to underdamped. We present\nsimple models which show that these unusual properties are closely related to\nthe memristor's internal dynamics. This tutorial complements the pedagogy of\nideal circuit elements (R,C, and L) and the properties of their circuits.",
        "positive": "Theoretical analysis of electronic band structure of 2-to-3-nm Si\n  nanocrystals: We introduce a general method which allows reconstruction of electronic band\nstructure of nanocrystals from ordinary real-space electronic structure\ncalculations. A comprehensive study of band structure of a realistic\nnanocrystal is given including full geometric and electronic relaxation with\nthe surface passivating groups. In particular, we combine this method with\nlarge scale density functional theory calculations to obtain insight into the\nluminescence properties of silicon nanocrystals of up to 3 nm in size depending\non the surface passivation and geometric distortion. We conclude that the band\nstructure concept is applicable to silicon nanocrystals with diameter larger\nthan $\\approx$ 2 nm with certain limitations. We also show how perturbations\ndue to polarized surface groups or geometric distortion can lead to\nconsiderable moderation of momentum space selection rules."
    },
    {
        "anchor": "Dependence of Modulation Amplitude on Electron Density in Unidirectional\n  Lateral Superlattices: The Effect of the Thickness of the Two-dimensional\n  Electron Gas: The amplitude V_0 of unidirectional periodic potential modulation introduced\nby a surface grating into a two-dimensional electron gas (2DEG) formed at\nAlGaAs/GaAs heterointerface is measured as a function of electron density n_e\nby analyzing commensurability oscillation of the magnetoresistance. The\nelectron density is varied either by applying a bias to a metallic back gate or\nby illumination. The amplitude decreases with increasing density, with the rate\n|dV_0/dn_e| roughly an order of magnitude larger for the former method. The\nresult is interpreted in terms of the rate, dE_1/d(delta E_c), of the change in\nthe first subband level E_1 in response to the variation of the conduction-band\nedge delta E_c above the heterointerface. The rate crucially depends on the\nthickness of the 2DEG.",
        "positive": "Temperature dependence of the ``0.7'' 2(e^2)/h quasi plateau in strongly\n  confined quantum point contacts: We present new results of the ``0.7'' 2(e^2)/h structure or quasi plateau in\nsome of the most strongly confined point contacts so far reported. This strong\nconfinement is obtained by a combination of shallow etching and metal gate\ndeposition on modulation doped GaAs/GaAlAs heterostructures. The resulting\nsubband separations are up to 20 meV, and as a consequence the quantized\nconductance can be followed at temperatures up to 30 K, an order of magnitude\nhigher than in conventional split gate devices. We observe pronounced quasi\nplateaus at several of the lowest conductance steps all the way from their\nformation around 1 K to 30 K, where the entire conductance quantization is\nsmeared out thermally. We study the deviation of the conductance from ideal\ninteger quantization as a function of temperature, and we find an activated\nbehavior, exp(-T_a/T), with a density dependent activation temperature T_a of\nthe order of 2 K. We analyze our results in terms of a simple theoretical model\ninvolving scattering against plasmons in the constriction."
    },
    {
        "anchor": "Application of Convolutional Neural Network to TSOM Images for\n  Classification of 6 nm Node Patterned Defects: With the rapid growth in the semiconductor industry, it is becoming critical\nto detect and classify increasingly smaller patterned defects. Recently machine\nlearning, including deep learning, has come to aid in this endeavor in a big\nway. However, the literature shows that it is challenging to successfully\nclassify defect types at the 6 nm node with 100% accuracy using low-cost and\nhigh-volume-manufacturing compatible optical imaging methods. Here we combine a\nconvolutional neural network (CNN) with that of an optical imaging method\ncalled through-focus scanning optical microscopy (TSOM) to successfully\nclassify patterned defects for the 6 nm node targets using simulated optical\nimages at the 193 nm illumination wavelength. We demonstrate the successful\nclassification of eight variations of the defects, including the 3 nm\ndifference in the defect size in one dimension, which is over 50 times smaller\nthan the illumination wavelength used.",
        "positive": "Conservation of energy, density of states and spin lattice relaxation: The starting point of all NMR experiments is a spin polarization which\ndevelops when we place the sample in static magnetic field $B_0$. There are\nexcess of spins aligned along $B_0$ (spin up with lower energy) than spins\naligned opposite (spin down with higher energy) to the field $B_0$. A natural\nquestion is what is the source of this excess spin polarization because\nrelaxation mechanisms can flip a up spin to a down spin and vice-versa. The\nanswer lies in the density of states. When a molecule with spin down flips to\nspin up it loses energy. This energy goes into increasing the kinetic energy of\nthe molecule in the gas/solution phase. At this increased kinetic energy, there\nare more rotational-translational states accessible to the molecule than at\nlower energy. This increases the probability the molecule will spend in spin up\nstate (higher kinetic energy state). This is the source of excess polarization.\nIn this paper, we use an argument based on equipartition of energy to\nexplicitly count the excess states that become accessible to the molecule when\nits spin is flipped from down to up. Using this counting, we derive the\nfamiliar Boltzmann distribution of the ratio of up vs down spins. Although\nprima facie, there is nothing new in this paper, we find the mode counting\nargument for excess states interesting. Furthermore, the paper stresses the\nfact that spin polarization arises from higher density of states at increased\nkinetic energy of molecules."
    },
    {
        "anchor": "Resonant Tunnelling through InAs Quantum Dots in Tilted Magnetic Fields:\n  Experimental Determination of the g-factor Anisotropy: We have determined the Land\\'e factor g* in self-organized InAs quantum dots\nusing resonant-tunnelling experiments. With the magnetic field applied parallel\nto the growth direction z we find g*_\\parallel = 0.75 for the specific dot\ninvestigated. When the magnetic field is tilted away by theta from the growth\naxis, g* gradually increases up to a value g*_\\perp = 0.92 when B \\perp z. Its\nangular dependence is found to follow the phenomenological behaviour g* (theta)\n= \\sqrt{(g*_\\parallel cos(theta)^2 + (g*_\\perp sin(theta)^2}.",
        "positive": "Understanding the structure of the first atomic contact in Gold: We have studied experimentally the phenomena of jump-to-contact (JC) and\njump-out-of-contact (JOC) in gold electrodes. JC can be observed at the first\ncontact when the two metals approach each other while JOC occurs in the last\ncontact before breaking. When the indentation depth between the electrodes is\nlimited to a certain value of conductance, a highly reproducible behaviour in\nthe evolution of the conductance can be obtained for hundreds of cycles of\nformation and rupture. Molecular dynamics simulations of this process show how\nthe two metallic electrodes are shaped into tips of a well-defined\ncrystallographic structure formed through a mechanical annealing mechanism. We\nreport a detailed analysis of the atomic configurations obtained before contact\nand rupture of these stable structures and obtained their conductance using\nfirst-principlesquantum transport calculations. These results help us\nunderstand the values of conductance obtained experimentally in the JC and JOC\nphenomena and improve our understanding of atomic-sized contacts and the\nevolution of their structural characteristics."
    },
    {
        "anchor": "The effect of screening long-range Coulomb interactions on the metallic\n  behavior in two-dimensional hole systems: We have developed a technique utilizing a double quantum well heterostructure\nthat allows us to study the effect of a nearby ground-plane on the metallic\nbehavior in a GaAs two-dimensional hole system (2DHS) in a single sample and\nmeasurement cool-down, thereby maintaining a constant disorder potential. In\ncontrast to recent measurements of the effect of ground-plane screening of the\nlong-range Coulomb interaction in the insulating regime, we find surprisingly\nlittle effect on the metallic behavior when we change the distance between the\n2DHS and the nearby ground-plane.",
        "positive": "Mesoscopic charge quantization: We study the Coulomb blockade in a chaotic quantum dot connected to a lead by\na single channel at nearly perfect transmission. We take into account quantum\nfluctuations of the dot charge and a finite level spacing for electron states\nwithin the dot. Mesoscopic fluctuations of thermodynamic and transport\nproperties in the Coulomb blockade regime exist at any transmission\ncoefficient. In contrast to the previous theories, we show that by virtue of\nthese mesoscopic fluctuations, the Coulomb blockade is not destroyed completely\neven at perfect transmission. The oscillatory dependence of all the observable\ncharacteristics on the gate voltage is preserved, its period is still defined\nby the charge of a single electron. However, phases of those oscillations are\nrandom; because of the randomness, the Coulomb blockade shows up not in the\naverages but in the correlation functions of the fluctuating observables (e.g.,\ncapacitance or tunneling conductance). This phenomenon may be called\n\"mesoscopic charge quantization\"."
    },
    {
        "anchor": "Reply to `Comment on \"Absence versus Presence of Dissipative Quantum\n  Phase Transition in Josephson Junctions\"': We reply to the comments on our previous paper Physical Review Letters, Vol.\n129, 087001 (2022), raised by Th\\'eo S\\'epulcre, Serge Florens, and Izak Snyman\nin arXiv:2210.00742.",
        "positive": "Improved effective equation for the Rashba spin-orbit coupling in\n  semiconductor nanowires: Semiconductor Rashba nanowires are quasi-one dimensional systems that have\nlarge spin-orbit (SO) coupling arising from a broken inversion symmetry due to\nan external electric field. There exist parametrized multiband models that can\ndescribe accurately this effect. However, simplified single band models are\nhighly desirable to study geometries of recent experimental interest, since\nthey may allow to incorporate the effects of the low dimensionality and the\nnanowire electrostatic environment at a reduced computational cost. Commonly\nused conduction band approximations, valid for bulk materials, greatly\nunderestimate the SO coupling in Zinc-blende crystal structures and\noverestimate it for Wurtzite ones when applied to finite cross-section wires,\nwhere confinement effects turn out to play an important role. We demonstrate\nhere that an effective equation for the linear Rashba SO coupling of the\nsemiconductor conduction band can reproduce the behavior of more sophisticated\neight-band k$\\cdot$p model calculations. This is achieved by adjusting a single\neffective parameter that depends on the nanowire crystal structure and its\nchemical composition. We further compare our results to the Rashba coupling\nextracted from magnetoconductance measurements in several experiments on InAs\nand InSb nanowires, finding excellent agreement. This approach may be relevant\nin systems where Rashba coupling is known to play a major role, such as in\nspintronic devices or Majorana nanowires."
    },
    {
        "anchor": "Near-Infrared and Visible-range Optoelectronics in 2D Hybrid\n  Perovskite/Transition Metal Dichalcogenide Heterostructures: The application of ultrathin two-dimensional (2D) perovskites in\nnear-infrared and visible-range optoelectronics has been limited owing to their\ninherent wide bandgaps, large excitonic binding energies and low optical\nabsorption at higher wavelengths. Here, we show that by tailoring interfacial\nband alignments via conjugation with low-dimensional materials like monolayer\ntransition metal dichalcogenides (TMD), the functionalities of 2D perovskites\ncan be extended to diverse, visible-range photophysical applications. Based on\nthe choice of individual constituents in the 2D perovskite/TMD\nheterostructures, our first principles calculations demonstrate widely tunable\ntype-II band gaps, carrier effective masses and band offsets to enable an\neffective separation of photogenerated excitons for enhanced photodetection and\nphotovoltaic applications. In addition, we show the possibilities of achieving\na type-I band alignment for recombination based light emitters as well as a\ntype-III configuration for tunnelling devices. Further, we evaluate the effect\nof strain on the electronic properties of the heterostructures to show a\nsignificant strain tolerance, making them prospective candidates in flexible\nphotosensors.",
        "positive": "Nonvolatile spin field effect transistor based on VSi2N4/Sc2CO2\n  multiferroic heterostructure: We report first-principles calculations that propose a nonvolatile spin field\neffect transistor (spin- FET) based on a van der Waals multiferroic\nheterostructure, i.e., VSi2N4/Sc2CO2. We find that the inversion of\nferroelectric polarization of monolayer Sc2CO2 can efficiently modulate the\nelectronic states of monolayer VSi2N4. A half-metal to half-semiconductor phase\ntranslation of VSi2N4 can be efficiently realized, which leads to distinct\nelectronic transport properties. We additionally construct a spin-FET device\nbased on the multiferroic heterostructure. We find that the VSi2 N4 /Sc2 CO2\nbased Spin-FET has remarkable all-electric-controlled performance. A large\non-off current ratio of about 650% induced by the inversion of Sc2CO2\nferroelectric polarization can be obtained under a small bias voltage (0.02 V).\nWe also find an interesting spatially-separated spin-polarized transport\nphenomenon, with the pure spin-up (spin-down) electrons transporting merely in\nVSi2N4 (Sc2CO2). Our study provides a promising approach for constructing\nlow-energy-dissipation and nonvolatile FET devices."
    },
    {
        "anchor": "Spaser as Nanoscale Quantum Generator and Ultrafast Amplifier: Nanoplasmonics has recently experienced explosive development with many novel\nideas and dramatic achievements in both fundamentals and applications. The\nspaser has been predicted and observed experimentally as an active element --\ngenerator of coherent local fields. Even greater progress will be achieved if\nthe spaser could function as a ultrafast nanoamplifier -- an optical\ncounterpart of the MOSFET (metal-oxide-semiconductor field-effect transistor).\nA formidable problem with this is that the spaser has the inherent feedback\ncausing quantum generation of nanolocalized surface plasmons and saturation and\nconsequent elimination of the net gain, making it unsuitable for amplification.\nWe have overcome this inherent problem and shown that the spaser can perform\nfunctions of an ultrafast nanoamplifier in two modes: transient and bistable.\nOn the basis of quantum density matrix (optical Bloch) equations we have shown\nthat the spaser amplifies with gain greater than 50, the switching time less or\non the order of 100 fs (potentially, 10 fs). This prospective spaser technology\nwill further broaden both fundamental and applied horizons of nanoscience, in\nparticular, enabling ultrafast microprocessors working at 10 to 100 THz clock\nspeed. Other prospective applications are in ultrasensing, ultradense and\nultrafast information storage, and biomedicine. The spasers are based on metals\nand, in contrast to semiconductors, are highly resistive to ionizing radiation,\nhigh temperatures, microwave radiation, and other adverse environments.",
        "positive": "Strained graphene: tight-binding and density functional calculations: We determine the band structure of graphene under strain using density\nfunctional calculations. The ab-initio band strucure is then used to extract\nthe best fit to the tight-binding hopping parameters used in a recent\nmicroscopic model of strained graphene. It is found that the hopping parameters\nmay increase or decrease upon increasing strain, depending on the orientation\nof the applied stress. The fitted values are compared with an available\nparametrization for the dependence of the orbital overlap on the distance\nseparating the two carbon atoms. It is also found that strain does not induce a\ngap in graphene, at least for deformations up to 10%."
    },
    {
        "anchor": "\"Creeping conductance\" in nonstationary granular systems and artificial\n  arrays: We consider a nonstationary array of conductors, connected by resistances\nthat fluctuate with time. The charge transfer between a particular pair of\nconductors is supposed to be dominated by \"electrical breakdowns\" -- the\nmoments when the corresponding resistance is close to zero. An amount of\ncharge, transferred during a particular breakdown, is controlled by the\ncondition of minimum for the electrostatic energy of the system. We find the\nconductivity, relaxation rate, and fluctuations for such a system within the\n\"classical approximation\", valid, if the typical transferred charge is large\ncompared to $e$. We discuss possible realizations of the model for colloidal\nsystems and arrays of polymer-linked grains.",
        "positive": "Determining the Location and Cause of Unintentional Quantum Dots in a\n  Nanowire: We determine the locations of unintentional quantum dots (U-QDs) in a silicon\nnanowire with a precision of a few nanometers by comparing the capacitances to\nmultiple gates with a capacitance simulation. Because we observe U-QDs in the\nsame location of the wire in multiple devices, their cause is likely to be an\nunintended consequence of the fabrication, not random atomic-scale defects as\nis typically assumed. The locations of the U-QDs appear consistent with\nconduction band modulation from strain from the oxide and the gates. This\nallows us to suggest methods to reduce the frequency of U-QDs."
    },
    {
        "anchor": "Spin mediated enhanced negative magnetoresistance in Ni80Fe20 and\n  p-silicon bilayer: In this work, we present an experimental study of spin mediated enhanced\nnegative magnetoresistance in Ni80Fe20 (50 nm)/p-Si (350 nm) bilayer. The\nresistance measurement shows a reduction of ~2.5% for the bilayer specimen as\ncompared to 1.3% for Ni80Fe20 (50 nm) on oxide specimen for an out-of-plane\napplied magnetic field of 3T. In the Ni80Fe20-only film, the negative\nmagnetoresistance behavior is attributed to anisotropic magnetoresistance. We\npropose that spin polarization due to spin-Hall effect is the underlying cause\nof the enhanced negative magnetoresistance observed in the bilayer. Silicon has\nweak spin orbit coupling so spin Hall magnetoresistance measurement is not\nfeasible. We use V2{\\omega} and V3{\\omega} measurement as a function of\nmagnetic field and angular rotation of magnetic field in direction normal to\nelectric current to elucidate the spin-Hall effect. The angular rotation of\nmagnetic field shows a sinusoidal behavior for both V2{\\omega} and V3{\\omega},\nwhich is attributed to the spin phonon interactions resulting from the\nspin-Hall effect mediated spin polarization. We propose that the spin\npolarization leads to a decrease in hole-phonon scattering resulting in\nenhanced negative magnetoresistance.",
        "positive": "Electric field modulation of Schottky barrier height in graphene/MoSe2\n  van der Waals heterointerface: We demonstrate a vertical field-effect transistor based on a graphene/MoSe2\nvan der Waals (vdW) heterostructure. The vdW interface between the graphene and\nMoSe2 exhibits a Schottky barrier with an ideality factor of around 1.3,\nsuggesting a high-quality interface. Owing to the low density of states in\ngraphene, the position of the Fermi level in the graphene can be strongly\nmodulated by an external electric field. Therefore, the Schottky barrier height\nat the graphene/MoSe2 vdW interface is also modulated. We demonstrate a large\ncurrent ON-OFF ratio of 10^5. These results point to the potential high\nperformance of the graphene/MoSe2 vdW heterostructure for electronics\napplications."
    },
    {
        "anchor": "Andreev reflection from a topological superconductor with chiral\n  symmetry: It was pointed out by Tewari and Sau that chiral symmetry (H -> -H if e <->\nh) of the Hamiltonian of electron-hole (e-h) excitations in an N-mode\nsuperconducting wire is associated with a topological quantum number\nQ\\in\\mathbb{Z} (symmetry class BDI). Here we show that Q=Tr(r_{he}) equals the\ntrace of the matrix of Andreev reflection amplitudes, providing a link with the\nelectrical conductance G. We derive G=(2e^2/h)|Q| for |Q|=N,N-1, and more\ngenerally provide a Q-dependent upper and lower bound on G. We calculate the\nprobability distribution P(G) for chaotic scattering, in the circular ensemble\nof random-matrix theory, to obtain the Q-dependence of weak localization and\nmesoscopic conductance fluctuations. We investigate the effects of chiral\nsymmetry breaking by spin-orbit coupling of the transverse momentum (causing a\nclass BDI-to-D crossover), in a model of a disordered semiconductor nanowire\nwith induced superconductivity. For wire widths less than the spin-orbit\ncoupling length, the conductance as a function of chemical potential can show a\nsequence of 2e^2/h steps - insensitive to disorder.",
        "positive": "The single electron R-pump: first experiment: We fabricated and tested the single electron R-pump, i.e. a three-junction Al\ncircuit with on-chip Cr resistors. We show that due to the presence of the\nresistors (R > h/e^2 = 25.8 kOhm), the accuracy of electron transfer in the\nR-pump can approach the level of 10^-8. Preliminary results of experiment with\nthe R-pump made at PTB are reported."
    },
    {
        "anchor": "Influence of nonequilibrium phonons on the amplitude of magnetoquantum\n  oscillations in the point-contact resistance: For metallic point contacts with Be and Al the magnetoquantum oscillations in\nthe contact resistance have been investigated as a function of the applied\nvoltage over the contact. For one set of point contacts the oscillation\namplitude is found to vary nonmonotonously with the applied voltage with\nsimilarities to the point-contact spectrum of the electron-phonon interaction.\nThe other part of the investigated point contacts shows a decrease of the\noscillation amplitude with increasing bias voltage. For the understanding of\nthe voltage dependence of the amplitude of the point-contact magnetoresistance\noscillations the influence of nonequilibrium phonons generated by the\nballistically injected electrons will be discussed.",
        "positive": "Charged excitons and biexcitons in laterally coupled InGaAs quantum dots: We present results of atomistic empirical pseudopotential calculations and\nconfiguration interaction for excitons, positive and negative trions (X\\pm),\npositive and negative quartons (X2\\pm) and biexcitons. The structure\ninvestigated are laterally aligned InGaAs quantum dot molecules embedded in\nGaAs under a lateral electric field. The rather simple energetic of excitons\nbecomes more complex in the case of charged quasiparticles but remains\ntractable. The negative trion spectrum shows four anticrossings in the\npresently available range of fields while the positive trion shows two. The\nmagnitude of the anticrossings reveals many-body effects in the carrier\ntunneling process that should be experimentally accessible."
    },
    {
        "anchor": "Electronic transport in single-helical protein molecules: Effects of\n  multiple charge conduction pathways and helical symmetry: We propose a tight-binding model to investigate electronic transport\nproperties of single helical protein molecules incorporating both the helical\nsymmetry and the possibility of multiple charge transfer pathways. Our study\nreveals that due to existence of both the multiple charge transfer pathways and\nhelical symmetry, the transport properties are quite rigid under influence of\nenvi- ronmental fluctuations which indicates that these biomolecules can serve\nas better alternatives in nanoelectronic devices than its other biological\ncounterparts e.g., single-stranded DNA.",
        "positive": "Metallic Surface States Probed Within the Microwave Skin Depth of the\n  Putative Topological Insulator YBiPt Compound: Electron Spin Resonance (ESR) experiments of diluted Nd$^{3+}$ ions in the\nclaimed topological insulator (TI) YBiPt are reported. Powdered samples with\ngrain size from $\\approx$ 100 $\\mu$m to $\\approx$ 2,000 $\\mu$m were\ninvestigated. At low temperatures, 1.6 K $\\lesssim$ \\emph{T} $\\lesssim$ 20 K,\nthe X-band ($9.4$ GHz) ESR spectra show a \\emph{g}-value of 2.66(4) and a\nDysonian resonance lineshape which shows a remarkably unusual temperature,\nconcentration, microwave power and particle size dependence. These results\nindicate that metallic and insulating behavior coexist within a skin depth of\n$\\delta \\approx$ 15 $\\mu$m. Furthermore, the Nd$^{3+}$ spin dynamics in YBiPt\nare consistent with the existence of a \\emph{phonon-bottleneck process} which\nallows the energy absorbed by the Nd$^{3+}$ ions at resonance to reach the\nthermal bath via the conduction electrons in the metallic surface states of\nYBiPt. These results are discussed in terms of the claimed topological\nsemi-metal properties of YBiPt."
    },
    {
        "anchor": "Non-Hermitian topological phase transitions for quantum spin Hall\n  insulators: The interplay between non-Hermiticity and topology opens an exciting avenue\nfor engineering novel topological matter with unprecedented properties. While\nprevious studies have mainly focused on one-dimensional systems or Chern\ninsulators, here we investigate topological phase transitions to/from quantum\nspin Hall (QSH) insulators driven by non-Hermiticity. We show that a trivial to\nQSH insulator phase transition can be induced by solely varying non-Hermitian\nterms, and there exists exceptional edge arcs in QSH phases. We establish two\ntopological invariants for characterizing the non-Hermitian phase transitions:\ni) with time-reversal symmetry, the biorthogonal $\\mathbb{Z}_2$ invariant based\non non-Hermitian Wilson loops, and ii) without time-reversal symmetry, a\nbiorthogonal spin Chern number through biorthogonal decompositions of the Bloch\nbundle of the occupied bands. These topological invariants can be applied to a\nwide class of non-Hermitian topological phases beyond Chern classes, and\nprovides a powerful tool for exploring novel non-Hermitian topological matter\nand their device applications.",
        "positive": "Band energy landscapes in twisted homobilayers of transition metal\n  dichalcogenides: Twistronic assembly of 2D materials employs the twist angle between adjacent\nlayers as a tuning parameter for designing the electronic and optical\nproperties of van der Waals heterostructures. Here, we study how interlayer\nhybridization, weak ferroelectric charge transfer between layers, and\npiezoelectric response to deformations set the valence and conduction band\nedges across the moir{\\'e} supercell in twistronic homobilayers of MoS$_2$,\nMoSe$_2$, WS$_2$ and WSe$_2$. We show that, due to the lack of inversion\nsymmetry in the monolayer crystals, bilayers with parallel (P) and\nanti-parallel (AP) unit cell orientations display contrasting behaviors. For\nP-bilayers at small twist angles we find band edges in the middle of triangular\ndomains of preferential stacking. In AP-bilayers at marginal twist angles\n($\\theta_{AP} < 1^\\circ$) the band edges are located in small regions around\nthe intersections of domain walls, giving highly localized quantum dot states."
    },
    {
        "anchor": "Intersubband transitions in nonpolar GaN/Al(Ga)N heterostructures in the\n  short and mid-wavelength infrared regions: This paper assesses nonpolar m- and a-plane GaN/Al(Ga)N multi-quantum-wells\ngrown on bulk GaN for intersubband optoelectronics in the short- and\nmid-wavelength infrared ranges. The characterization results are compared to\nthose for reference samples grown on the polar c-plane, and are verified by\nself-consistent Schr\\\"odinger-Poisson calculations. The best results in terms\nof mosaicity, surface roughness, photoluminescence linewidth and intensity, as\nwell as intersubband absorption are obtained from m-plane structures, which\ndisplay room-temperature intersubband absorption in the range from 1.5 to 2.9\num. Based on these results, a series of m-plane GaN/AlGaN multi-quantum-wells\nwere designed to determine the accessible spectral range in the mid-infrared.\nThese samples exhibit tunable room-temperature intersubband absorption from 4.0\nto 5.8 um, the long-wavelength limit being set by the absorption associated\nwith the second order of the Reststrahlen band in the GaN substrates.",
        "positive": "Theory optical excitation spectra and depolarization dynamics in bilayer\n  WS$_2$ from viewpoint of excimers: We investigate the optical excitation spectra and the photoluminescence\ndepolarization dynamics in bilayer WS$_2$. A different understanding of the\noptical excitation spectra in the recent photoluminescence experimentby Zhu\n{\\em et al.} [arXiv:1403.6224] in bilayer WS$_2$ is proposed. In the\nexperiment, four excitations (1.68, 1.93, 1.99 and 2.37 eV) are observed and\nidentified to be indirect exciton for the $\\Gamma$ valley, trion, A exciton and\nB exciton excitations, respectively, with the redshift for the A exciton energy\nmeasured to be 30$\\sim$50 meV when the sample synthesized from monolayer to\nbilayer. According to our study, by considering there exist both the\nintra-layer and charge-transfer excitons in the bilayer WS$_2$, with\ninter-layer hopping of the hole, there exists excimer state composed by the\nsuperposition of the intra-layer and charge-transfer exciton states.\nAccordingly, we show that the four optical excitations in the bilayer WS$_2$\nare the A charge-transfer exciton, ${\\rm A}'$ excimer, ${\\rm B}'$ excimer and B\nintra-layer exciton states, respectively, with the calculated resonance\nenergies showing good agreement with the experiment. In our picture, the\nspeculated indirect exciton, which involves a high-order phonon\nabsorption/emission process, is not necessary. Furthermore, the binding energy\nfor the excimer state is calculated to be 40 meV, providing reasonable\nexplanation for the experimentally observed energy redshift of the A exciton.\nBased on the excimer states, we further derive the exchange interaction\nHamiltonian. Then the photoluminescence depolarization dynamics due to the\nelectron-hole exchange interaction is studied in the pump-probe setup by the\nkinetic spin Bloch equations. We find that ......"
    },
    {
        "anchor": "Analytical model of the inertial dynamics of a magnetic vortex: We present an analytical model to account for the inertial dynamics of a\nmagnetic vortex. The model is based on a deformation of the core profile based\non the D\\\"oring kinetic field, whereby the deformation amplitudes are promoted\nto dynamical variables in a collective-coordinate approach that provides a\nnatural extension to the Thiele model. This extended model accurately describes\ncomplex transients due to inertial effects and the variation of the effective\nmass with velocity. The model also provides a quantitative description of the\ninertial dynamics leading up to vortex core reversal, which is analogous to the\nWalker transition in domain wall dynamics.",
        "positive": "Strong vibration nonlinearity in semiconductor-based nanomechanical\n  systems: We study the effect of the electron-phonon coupling on vibrational eigenmodes\nof nano- and micro-mechanical systems made of semiconductors with equivalent\nenergy valleys. We show that the coupling can lead to a strong mode\nnonlinearity. The mechanism is the lifting of the valley degeneracy by the\nstrain. The redistribution of the electrons between the valleys is controlled\nby a large ratio of the electron-phonon coupling constant to the electron\nchemical potential or temperature. We find the quartic in the strain terms in\nthe electron free energy, which determine the amplitude dependence of the mode\nfrequencies. This dependence is calculated for silicon micro-systems. It is\nsignificantly different for different modes and the crystal orientation, and\ncan vary nonmonotonously with the electron density and temperature."
    },
    {
        "anchor": "Tuneable spin injection in high-quality graphene with one-dimensional\n  contacts: Spintronics involves the development of low-dimensional electronic systems\nwith potential use in quantum-based computation. In graphene, there has been\nsignificant progress in improving spin transport characteristics by\nencapsulation and reducing impurities, but the influence of standard\ntwo-dimensional (2D) tunnel contacts, via pinholes and doping of the graphene\nchannel, remains difficult to eliminate. Here, we report the observation of\nspin injection and tuneable spin signal in fully-encapsulated graphene, enabled\nby van der Waals heterostructures with one-dimensional (1D) contacts. This\narchitecture prevents significant doping from the contacts, enabling\nhigh-quality graphene channels, currently with mobilities up to 130,000\ncm$^2$V$^{-1}$s$^{-1}$ and spin diffusion lengths approaching 20 ${\\mu}$m. The\nnanoscale-wide 1D contacts allow spin injection both at room and at low\ntemperature, with the latter exhibiting efficiency comparable with 2D tunnel\ncontacts. At low temperature, the spin signals can be enhanced by as much as an\norder of magnitude by electrostatic gating, adding new functionality.",
        "positive": "Induced Monolayer Altermagnetism in MnP(S,Se)$_3$ and FeSe: Altermagnets (AM) are a recently discovered third class of collinear magnets,\ndistinctly different from conventional ferromagnets (FM) and antiferromagnets\n(AF). AM have been actively researched in the last few years, but two aspects\nso far remain unaddressed: (1) Are there realistic 2D single-layer\naltermagnets? And (2) is it possible to functionalize a conventional AF into AM\nby external stimuli? In this paper we address both issues by demonstrating how\na well-known 2D AF, MnP(S,Se)$_3$ can be functionalized into strong AM by\napplying out-of-plane electric field. Of particular interest is that the\ninduced altermagnetism is of a higher even-parity wave symmetry than expected\nin 3D AM with similar crystal symmetries. We confirm our finding by\nfirst-principles calculations of the electronic structure and magnetooptical\nresponse. We also propose that recent observations of the time-reversal\nsymmetry breaking in the famous Fe-based superconducting chalchogenides, either\nin monolayer form or in the surface layer, may be related not to an FM, as\npreviously assumed, but to the induced 2D AM order. Finally, we show that\nmonolayer FeSe can simultaneously exhibit unconventional altermagnetic\ntime-reversal symmetry breaking and quantized spin Hall conductivity indicating\npossibility to research an intriquing interplay of 2D altermagnetism with\ntopological and superconducting states within a common crystal-potential\nenvironment."
    },
    {
        "anchor": "Unconventional double-bended saturation of optical transmission in\n  graphene due to many-particle interactions: We present a joint theory-experiment study on the transmission/absorption\nsaturation after ultrafast pulse excitation in graphene. We reveal an\nunconventional double-bended saturation behavior: Both bendings separately\nfollow the standard saturation model exhibiting two saturation fluences,\nhowever, the corresponding fluences differ by three orders of magnitude and\nhave different physical origin. Our results reveal that this new and unexpected\nbehavior can be ascribed to an interplay between fluence- and time-dependent\nmany-particle scattering processes and phase-space filling effects.",
        "positive": "Conditional quantum operation of two exchange-coupled single-donor spin\n  qubits in a MOS-compatible silicon device: Silicon nanoelectronic devices can host single-qubit quantum logic operations\nwith fidelity better than 99.9%. For the spins of an electron bound to a single\ndonor atom, introduced in the silicon by ion implantation, the quantum\ninformation can be stored for nearly 1 second. However, manufacturing a\nscalable quantum processor with this method is considered challenging, because\nof the exponential sensitivity of the exchange interaction that mediates the\ncoupling between the qubits. Here we demonstrate the conditional, coherent\ncontrol of an electron spin qubit in an exchange-coupled pair of $^{31}$P\ndonors implanted in silicon. The coupling strength, $J = 32.06 \\pm 0.06$ MHz,\nis measured spectroscopically with unprecedented precision. Since the coupling\nis weaker than the electron-nuclear hyperfine coupling $A \\approx 90$ MHz which\ndetunes the two electrons, a native two-qubit Controlled-Rotation gate can be\nobtained via a simple electron spin resonance pulse. This scheme is insensitive\nto the precise value of $J$, which makes it suitable for the scale-up of\ndonor-based quantum computers in silicon that exploit the\nMetal-Oxide-Semiconductor fabrication protocols commonly used in the classical\nelectronics industry."
    },
    {
        "anchor": "Landau theory and self-assembly of spherical nanoclusters and\n  nanoparticles with octahedral symmetry: Spherical nanoclusters and nanoparticles are rising materials whose\nfunctional design provides many useful applications ranging from catalysis,\nmolecular sensing, gas storage to drug targeting and delivery. Here, we develop\nphenomenological crystallization theory of such spherical structures with\noctahedral symmetries O and O_h. Within the developed theory, we propose a\nmethod, which is based on constructing irreducible octahedral density functions\nand allows to predict the positions of structural units in the spherical\nnanoobjects. The proposed theory explains the structures of the simplest known\nmetal nanoclusters, some metal-organic polyhedra and membrane protein\npolyhedral nanoparticles, and also predicts more complex chiral spherical\nstructures and achiral assemblies characterized by the geometry of semiregular\npolyhedra. A relationship between the constructed irreducible octahedral\nfunctions and spherical lattices, obtained by mapping a plane hexagonal order\nonto a spherical surface through an octahedron net, is discussed as well.",
        "positive": "Coherent states for dispersive pseudo-Landau-levels in strained\n  honeycomb lattices: Dirac fermions in graphene may experiment dispersive pseudo-Landau levels due\nto a homogeneous pseudomagnetic field and a position-dependent Fermi velocity\ninduced by strain. In this paper, we study the (semi-classical) dynamics of\nthese particles under such a physical context from an approach of coherent\nstates. For this purpose we use a Landau-like gauge to built Perelomov coherent\nstates by the action of a non-unitary displacement operator $D(\\alpha)$ on the\nfundamental state of the system. We analyze the time evolution of the\nprobability density and the generalized uncertainty principle as well as the\nWigner function for the coherent states. Our results show how $x$-momentum\ndependency affects the motion periodicity and the Wigner function shape in\nphase space."
    },
    {
        "anchor": "Anderson's theorem for correlated insulating states in twisted bilayer\n  graphene: The emergence of correlated insulating phases in magic-angle twisted bilayer\ngraphene exhibits strong sample dependence. Here, we derive an Anderson theorem\ngoverning the robustness against disorder of the Kramers intervalley coherent\n(K-IVC) state, a prime candidate for describing the correlated insulators at\neven fillings of the moir\\'e flat bands. We find that the K-IVC gap is robust\nagainst local perturbations, which are odd under $\\mathcal{PT}$, where\n$\\mathcal{P}$ and $\\mathcal{T}$ denote particle-hole conjugation and time\nreversal, respectively. In contrast, $\\mathcal{PT}$-even perturbations will in\ngeneral induce subgap states and reduce or even eliminate the gap. We use this\nresult to classify the stability of the K-IVC state against various\nexperimentally relevant perturbations. The existence of an Anderson theorem\nsingles out the K-IVC state from other possible insulating ground states.",
        "positive": "Automated Tabletop Exfoliation and Identification of Monolayer Graphene\n  Flakes: The discovery of graphene, one of the most-studied materials in condensed\nmatter physics due to its singular mechanical, optical, and electronic\nproperties, was enabled by manual ``Scotch Tape'' exfoliation. Nearly two\ndecades later, this method is still widely used to obtain chemically-pristine\nflakes of graphene and other 2D van der Waals materials. Unfortunately, the\nyield of large, pristine flakes with uniform thickness is inconsistent. Thus,\nsignificant time and effort are required to exfoliate and locate flakes\nsuitable for fabricating multilayer van der Waals heterostructures. Here, we\ndescribe a relatively affordable tabletop device (the ''eXfoliator'') that can\nreproducibly control key parameters and largely automate the exfoliation\nprocess. In a typical exfoliation run, the eXfoliator produces 3 or more large\n($\\ge400\\ \\mu$m$^2$) high-quality monolayers, allowing new users to produce\nlarge pristine graphene monolayers at a rate comparable to manual exfoliation\nby an experienced user. We use an automated mapping system and computer vision\nalgorithm to locate candidate flakes."
    },
    {
        "anchor": "Enhanced shot noise of multiple Andreev reflections in a carbon nanotube\n  quantum dot in SU(2) and SU(4) Kondo regimes: The sensitivity of shot noise to the interplay between Kondo correlations and\nsuperconductivity is investigated in a carbon nanotube quantum dot connected to\nsuperconducting electrodes. Depending on the gate voltage, the SU(2) and SU(4)\nKondo unitary regimes can be clearly identified. We observe enhancement of the\nshot noise via the Fano factor in the superconducting state. Its divergence at\nlow bias voltage, which is more pronounced in the SU(4) regime than in the\nSU(2) one, is larger than what is expected from proliferation of multiple\nAndreev reflections predicted by the existing theories. Our result suggests\nthat Kondo effect is responsible for this strong enhancement.",
        "positive": "Transport in random quantum dot superlattices: We present a novel model to calculate single-electron states in random\nquantum dot superlattices made of wide-gap semiconductors. The source of\ndisorder comes from the random arrangement of the quantum dots (configurational\ndisorder) as well as spatial inhomogeneities of their shape (morphological\ndisorder). Both types of disorder break translational symmetry and prevent the\nformation of minibands, as occurs in regimented arrays of quantum dots. The\nmodel correctly describes channel mixing and broadening of allowed energy bands\ndue to elastic scattering by disorder."
    },
    {
        "anchor": "High-Yield Production and Transfer of Graphene Flakes Obtained by Anodic\n  Bonding: We report large-yield production of graphene flakes on glass by anodic\nbonding. Under optimum conditions, we counted several tens of flakes with\nlateral size around 20-30 {\\mu}m and few tens of flakes with larger size.\n60-70% of the flakes have negligible D peak. We show that it is possible to\neasily transfer the flakes by wedging technique. The transfer on silicon does\nnot damage graphene and lowers the doping. The charge mobility of the\ntransferred flakes on silicon is of the order of 6000 cm^2/V s (at carrier\nconcentration of 10^12 cm^-2), which is typical for devices prepared on this\nsubstrate with exfoliated graphene.",
        "positive": "Landauer transport as a quasisteady state on finite chains under unitary\n  quantum dynamics: In this paper, we study the emergence of a Landauer transport regime from the\nquantum-mechanical dynamics of free electrons in a disordered tight-binding\nchain, which is coupled to finite leads with open boundaries. Both partitioned\nand partition-free initial conditions are analyzed and seen to give rise, for\nlarge enough leads, to the same spatially uniform quasi-steady-state current,\nwhich agrees with the Landauer value. The quasi-steady-state regime is preceded\nby a transient regime, which last for a time proportional to the length of the\ndisordered sample, and followed by recursions, after a time that is\nproportional to the lead size. These theoretical predictions may be of interest\nto future experiments on transport of fermionic ultra-cold atoms across optical\nlattices. We also observe finite-size current oscillations, superimposed on the\nquasi-steady-state, whose behavior depends crucially on the conditions\ninitially imposed on the system. Finally, we show how a time-resolved Kubo\nformula is able to reproduce this Landauer transport regime, as the leads grow\nbigger."
    },
    {
        "anchor": "Direct Bandgap Emission from Hexagonal Ge and SiGe Alloys: Silicon crystallized in the usual cubic (diamond) lattice structure has\ndominated the electronics industry for more than half a century. However, cubic\nsilicon (Si), germanium (Ge) and SiGe-alloys are all indirect bandgap\nsemiconductors that cannot emit light efficiently. Accordingly, achieving\nefficient light emission from group-IV materials has been a holy grail in\nsilicon technology for decades and, despite tremendous efforts, it has remained\nelusive. Here, we demonstrate efficient light emission from direct bandgap\nhexagonal Ge and SiGe alloys. We measure a subnanosecond,\ntemperature-insensitive radiative recombination lifetime and observe a similar\nemission yield to direct bandgap III-V semiconductors. Moreover, we demonstrate\nhow by controlling the composition of the hexagonal SiGe alloy, the emission\nwavelength can be continuously tuned in a broad range, while preserving a\ndirect bandgap. Our experimental findings are shown to be in excellent\nquantitative agreement with the ab initio theory. Hexagonal SiGe embodies an\nideal material system to fully unite electronic and optoelectronic\nfunctionalities on a single chip, opening the way towards novel device concepts\nand information processing technologies.",
        "positive": "Giant spin-orbit torque in a single ferrimagnetic metal layer: Antiferromagnets and compensated ferrimagnets offer opportunities to\ninvestigate spin dynamics in the 'terahertz gap' because their resonance modes\nlie in the 0.3 THz to 3 THz range. Despite some inherent advantages when\ncompared to ferromagnets, these materials have not been extensively studied due\nto difficulties in exciting and detecting the high-frequency spin dynamics,\nespecially in thin films. Here we show that spin-obit torque in a single layer\nof the highly spin-polarized compensated ferrimagnet Mn2RuxGa is remarkably\nefficient at generating spin-orbit fields \\mu_0H_eff, which approach 0.1x10-10\nT m2/A in the low-current density limit -- almost a thousand times the Oersted\nfield, and one to two orders of magnitude greater than the effective fields in\nheavy metal/ferromagnet bilayers. From an analysis of the harmonic Hall effect\nwhich takes account of the thermal contributions from the anomalous Nernst\neffect, we show that the antidamping component of the spin-orbit torque is\nsufficient to sustain self-oscillation. Our study demonstrates that spin\nelectronics has the potential to underpin energy-frugal, chip-based solutions\nto the problem of ultra high-speed information transfer."
    },
    {
        "anchor": "Charge control in laterally coupled double quantum dots: We investigate the electronic and optical properties of InAs double quantum\ndots grown on GaAs (001) and laterally aligned along the [110] crystal\ndirection. The emission spectrum has been investigated as a function of a\nlateral electric field applied along the quantum dot pair mutual axis. The\nnumber of confined electrons can be controlled with the external bias leading\nto sharp energy shifts which we use to identify the emission from neutral and\ncharged exciton complexes. Quantum tunnelling of these electrons is proposed to\nexplain the reversed ordering of the trion emission lines as compared to that\nof excitons in our system.",
        "positive": "Emulating topological chiral magnetic effects in artificial Weyl\n  semimetals: We realized highly tunable Weyl semimetal-bands and subsequently emulated the\ntopological chiral magnetic effects in superconducting quantum circuits.\nDriving the superconducting quantum circuits with elaborately designed\nmicrowave fields, we mapped the momentum space of a lattice to the parameter\nspace, realizing the Hamiltonian of a Weyl semimetal. By measuring the energy\nspectrum, we directly imaged the Weyl points of cubic lattices, whose\ntopological winding numbers were further determined from the Berry curvature\nmeasurement. In particular, we used an additional microwave field to produce a\nmomentum-dependent chemical potential, from which the chiral magnetic\ntopological current was extracted in the presence of an artificial magnetic\nfield. This pure topological current is proportional to the magnetic field,\nwhich is in contrast to the famous Ampere's law, and may have significant\nimpacts on topological materials and quantum devices."
    },
    {
        "anchor": "Specular Andreev reflection in thin films of topological insulators: We theoretically reveal the possibility of specular Andreev reflection in a\nthin film topological insulator normal-superconductor (N/S) junction in the\npresence of a gate electric field. The probability of specular Andreev\nreflection increases with the electric field, and electron-hole conversion with\nunit efficiency happens in a wide experimentally accessible range of the\nelectric field. We show that perfect specular Andreev reflection can occur for\nall angles of incidence with a particular excitation energy value. In addition,\nwe find that the thermal conductance of the structure displays exponential\ndependence on the temperature. Our results reveal the potential of the proposed\ntopological insulator thin-film-based N/S structure for the realization of\nintraband specular Andreev reflection.",
        "positive": "A many-electron tight binding method for the analysis of quantum dot\n  systems: We present a method which computes many-electron energies and eigenfunctions\nby a full configuration interaction which uses a basis of atomistic\ntight-binding wave functions. This approach captures electron correlation as\nwell as atomistic effects, and is well suited to solid state quantum dot\nsystems containing few electrons, where valley physics and disorder contribute\nsignificantly to device behavior. Results are reported for a two-electron\nsilicon double quantum dot as an example."
    },
    {
        "anchor": "Sequential Landau-Zener transitions in spin-orbit coupled systems: We investigate the Landau-Zener (LZ) process in spin-orbit coupled systems of\nsingle or multiple two-level (spin-$\\frac{1}{2}$) particles. The coupling\nbetween internal spin states and external vibrational states, a simple\nspin-orbit coupling (SOC), is induced by applying a spin-dependent harmonic\ntrap. Because of the SOC, the single-particle energy-level structures are\nmodified by the Franck-Condon (FC) effects, in which some avoided\nenergy-level-crossings (ELCs) are almost closed and some ELCs are opened. The\nclose of avoided ELCs and the open of ELCs result in the FC blockade and the\nvibrational transitions, respectively. For a given low sweeping rate, the\nsequential LZ transitions of ladder-like population transition can be induced\nby strong SOC. We derive an analytical formula for the final population which\nis well consistent with the numerical results. For a given strong SOC, the\nsequential LZ transitions are submerged in the non-adiabatic transitions if the\nsweeping rate is sufficiently high. Further, we study LZ transitions of\nmultiple interacting two-level Bose particles in a spin-dependent harmonic\ntrap. The interplay between the SOC effects and the interaction effects is\nexplored.",
        "positive": "Thermodynamic performance of hot-carrier solar cells: A quantum\n  transport model: In conventional solar cells, photogenerated carriers lose part of their\nenergy before they can be extracted to make electricity. The aim of hot-carrier\nsolar cells is to extract the carriers before this energy loss, thereby turning\nmore energy into electrical power. This requires extracting the carriers in a\nnonequilibrium (nonthermal) energy distribution. Here, we investigate the\nperformance of hot-carrier solar cells for such nonequilibrium distributions.\nWe propose a quantum transport model in which each energy-loss process (carrier\nthermalization, relaxation, and recombination) is simulated by a B\\\"uttiker\nprobe. We study charge and heat transport to analyze the hot-carrier solar\ncell's power output and efficiency, introducing partial efficiencies for\ndifferent loss processes and the carrier extraction. We show that producing\nelectrical power from a nonequilibrium distribution has the potential to\nimprove the output power and efficiency. Furthermore, in the limit where the\ndistribution is thermal, we prove that a boxcar-shaped transmission for the\ncarrier extraction maximizes the efficiency at any given output power."
    },
    {
        "anchor": "Two-dimensional nanoscale imaging of gadolinium spins via scanning probe\n  relaxometry with a single spin in diamond: Spin-labeling of molecules with paramagnetic ions is an important approach\nfor determining molecular structure, however current ensemble techniques lack\nthe sensitivity to detect few isolated spins. In this Letter, we demonstrate\ntwo-dimensional nanoscale imaging of paramagnetic gadolinium compounds using\nscanning relaxometry of a single nitrogen vacancy (NV) center in diamond.\nGadopentetate dimeglumine attached to an atomic force microscope tip is\ncontrollably interacted with and detected by the NV center, by virtue of the\nfact that the NV exhibits fast relaxation in the fluctuating magnetic field\ngenerated by electron spin flips in the gadolinium. Using this technique, we\ndemonstrate a reduction in the $T_1$ relaxation time of the NV center by over\ntwo orders of magnitude, probed with a spatial resolution of 20 nm. Our result\nexhibits the viability of the technique for imaging individual spins attached\nto complex nanostructures or biomolecules, along with studying the magnetic\ndynamics of isolated spins.",
        "positive": "Angular Dependent Magnetization Dynamics of Kagome Artificial Spin Ice\n  Incorporating Topological Defects: We report angular-dependent spin-wave spectroscopy on kagome artificial spin\nice made of large arrays of interconnected Ni80Fe20 nanobars. Spectra taken in\nsaturated and disordered states exhibit a series of resonances with\ncharacteristic in-plane angular dependencies. Micromagnetic simulations allow\nus to interpret characteristic resonances of a two-step magnetization reversal\nof the nanomagnets. The dynamic properties are consistent with topological\ndefects that are provoked via a magnetic field applied at specific angles.\nSimulations that we performed on previously investigated kagome artificial spin\nice consisting of isolated nanobars show characteristic discrepancies in the\nspin wave modes which we explain by the absence of vertices."
    },
    {
        "anchor": "Asymmetry-induced effects in Kondo quantum dots coupled to ferromagnetic\n  leads: We study the spin-resolved transport through single-level quantum dots\nstrongly coupled to ferromagnetic leads in the Kondo regime, with a focus on\ncontact and material asymmetry-related effects. By using the numerical\nrenormalization group method, we analyze the dependence of relevant spectral\nfunctions, linear conductance and tunnel magnetoresistance on the system\nasymmetry parameters. In the parallel magnetic configuration of the device the\nKondo effect is generally suppressed due to the presence of exchange field,\nirrespective of system's asymmetry. In the antiparallel configuration, on the\nother hand, the Kondo effect can develop if the system is symmetric. We show\nthat even relatively weak asymmetry may lead to the suppression of the Kondo\nresonance in the antiparallel configuration and thus give rise to nontrivial\nbehavior of the tunnel magnetoresistance. In addition, by using the\nsecond-order perturbation theory we derive general formulas for the exchange\nfield in both magnetic configurations of the system.",
        "positive": "Control of a spin qubit in a lateral GaAs quantum dot based on symmetry\n  of gating potential: We study the influence of quantum dot symmetry on the Rabi frequency and\nphonon induced spin relaxation rate in a single electron GaAs spin qubit. We\nfind that anisotropic dependence on the magnetic field direction is independent\nof the choice of the gating potential. Also, we discover that relative\norientation of the quantum dot, with respect to the crystallographic frame, is\nrelevant in systems with ${\\bf C}_{1{\\rm v}}$, ${\\bf C}_{2{\\rm v}}$, or ${\\bf\nC}_{n}$ ($n\\neq4r$) symmetry. To demonstrate the important impact of the gating\npotential shape on the spin qubit lifetime, we compare the effects of an\nequilateral triangle, square, and rectangular confinement with the known\nresults for the harmonic potential. In the studied cases, enhanced spin qubit\nlifetime is revealed, reaching almost six orders of magnitude increase for the\nequilateral triangle gating."
    },
    {
        "anchor": "Vertically coupled double quantum rings at zero magnetic field: Within local-spin-density functional theory, we have investigated the\n`dissociation' of few-electron circular vertical semiconductor double quantum\nring artificial molecules at zero magnetic field as a function of inter-ring\ndistance. In a first step, the molecules are constituted by two identical\nquantum rings. When the rings are quantum mechanically strongly coupled, the\nelectronic states are substantially delocalized, and the addition energy\nspectra of the artificial molecule resemble those of a single quantum ring in\nthe few-electron limit. When the rings are quantum mechanically weakly coupled,\nthe electronic states in the molecule are substantially localized in one ring\nor the other, although the rings can be electrostatically coupled. The effect\nof a slight mismatch introduced in the molecules from nominally identical\nquantum wells, or from changes in the inner radius of the constituent rings,\ninduces localization by offsetting the energy levels in the quantum rings. This\nplays a crucial role in the appearance of the addition spectra as a function of\ncoupling strength particularly in the weak coupling limit.",
        "positive": "Longitudinal magnetoconductance and the planar Hall effect in a lattice\n  model of tilted Weyl fermions: The experimental verification of chiral anomaly in Weyl semimetals is an\nactive area of investigation in modern condensed matter physics, which\ntypically relies on the combined signatures of longitudinal magnetoconductance\n(LMC) along with the planar Hall effect (PHE). It has recently been shown that\nfor weak non-quantizing magnetic fields, a sufficiently strong finite\nintervalley scattering drives the system to switch the sign of LMC from\npositive to negative. Here we unravel another independent source that produces\nthe same effect. Specifically, a smooth lattice cutoff to the linear\ndispersion, which is ubiquitous in real Weyl materials, introduces nonlinearity\nin the problem and also drives the system to exhibit negative LMC for\nnon-collinear electric and magnetic fields even in the limit of vanishing\nintervalley scattering. We examine longitudinal magnetoconductivity and the\nplanar Hall effect semi-analytically for a lattice model of tilted Weyl\nfermions within the Boltzmann approximation. We independently study the effects\nof a finite lattice cutoff and tilt parameters and construct phase diagrams in\nrelevant parameter spaces that are relevant for diagnosing chiral anomaly in\nreal Weyl materials."
    },
    {
        "anchor": "Dynamical Piezomagnetic Effect in Time-Reversal Invariant Weyl\n  Semimetals with Axionic Charge-Density Waves: Charge-density waves (CDWs) in Weyl semimetals (WSMs) have been shown to\ninduce an exotic axionic insulating phase in which the sliding mode (phason) of\nthe CDW acts as a dynamical axion field, giving rise to a large positive\nmagneto-conductance [Wang et al., Phys. Rev. B 87, 161107(R) (2013); Roy et\nal., Phys. Rev. B 92, 125141 (2015); J. Gooth et al., Nature 575, 315 (2019)].\nIn this work, we predict that dynamical strain can induce a bulk orbital\nmagnetization in time-reversal- (TR-) invariant WSMs that are gapped by a CDW.\nWe term this effect the \"dynamical piezomagnetic effect\" (DPME). Unlike in [J.\nGooth et al., Nature 575, 315 (2019)], the DPME introduced in this work occurs\nin a bulk-constant (i.e., static and spatially homogeneous in the bulk) CDW,\nand does not rely on fluctuations, such as a phason. By studying the low-energy\neffective theory and a minimal tight-binding (TB) model, we find that the DPME\noriginates from an effective valley axion field that couples the\nelectromagnetic gauge field with a strain-induced pseudo-gauge field. In\nparticular, whereas the piezoelectric effects studied in previous works are\ncharacterized by 2D Berry curvature, the DPME represents the first example of a\nfundamentally 3D strain effect originating from the Chern-Simons 3-form. We\nfurther find that the DPME has a discontinuous change at a critical value of\nthe phase of the CDW order parameter. We demonstrate that, when there is a jump\nin the DPME, the surface of the system undergoes a topological quantum phase\ntransition (TQPT), while the bulk remains gapped. Hence, the DPME provides a\nbulk signature of the boundary TQPT in a TR-invariant Weyl-CDW.",
        "positive": "Conductance Fluctuations in a Metallic Wire Interrupted by a Tunnel\n  Junction: The conductance fluctuations of a metallic wire which is interrupted by a\nsmall tunnel junction has been explored experimentally. In this system, the\nbias voltage V, which drops almost completely inside the tunnel barrier, is\nused to probe the energy dependence of conductance fluctuations due to disorder\nin the wire. We find that the variance of the fluctuations is directly\nproportional to V. The experimental data are consistently described by a\ntheoretical model with two phenomenological parameters: the phase breaking time\nat low temperatures and the diffusion coefficient."
    },
    {
        "anchor": "Quantum effects in graphitic materials: Colossal magnetoresistance,\n  Andreev reflections, Little-Parks effect, ferromagnetism, and granular\n  superconductivity: Unlike the more common local conductance spectroscopy, nonlocal conductance\ncan differentiate between nontopological zero-energy modes localized around\ninhomogeneities, and true Majorana edge modes in the topological phase. In\nparticular, negative nonlocal conductance is dominated by the crossed Andreev\nreflection. In graphene, the Andreev reflection and the inter-band Klein\ntunneling couple electron-like and hole-like states through the action of\neither a superconducting (SC) pair potential or an electrostatic potential. We\nare here probing quantum phenomena in modified graphitic samples. Four-point\ncontact transport measurements at cryogenic to room temperatures were conducted\nusing a Quantum Design Physical Property Measurement System. The observed\nnegative nonlocal differential conductance Gdiff probes the Andreev reflection\nat the walls of the SC grains coupled by Josephson effect through the\nsemiconducting matrix. In addition, Gdiff shows the butterfly shape that is\ncharacteristic to resistive random-access memory devices. In a magnetic field,\nthe Andreev reflection counters the effect of the otherwise lowered conduction.\nAt low temperatures, the magnetoresistance shows irreversible yet strong\ncolossal oscillations that are known to be quantum in nature. In addition, we\nhave found evidence for seemingly granular SC as well as ferromagnetism.\nMoreover, the Little-Parks effect is revealed in both the classical\nsmall-amplitude and the phase-slip driven large-amplitude oscillations in the\nmagnetoresistance. Thus, graphitic materials show potential for quantum\nelectronics applications, including rectification and topological states.",
        "positive": "Princess and the Pea at the nanoscale: Wrinkling and delamination of\n  graphene on nanoparticles: Thin membranes exhibit complex responses to external forces or geometrical\nconstraints. A familiar example is the wrinkling, exhibited by human skin,\nplant leaves, and fabrics, resulting from the relative ease of bending versus\nstretching. Here, we study the wrinkling of graphene, the thinnest and stiffest\nknown membrane, deposited on a silica substrate decorated with silica\nnanoparticles. At small nanoparticle density monolayer graphene adheres to the\nsubstrate, detached only in small regions around the nanoparticles. With\nincreasing nanoparticle density, we observe the formation of wrinkles which\nconnect nanoparticles. Above a critical nanoparticle density, the wrinkles form\na percolating network through the sample. As the graphene membrane is made\nthicker, global delamination from the substrate is observed. The observations\ncan be well understood within a continuum elastic model and have important\nimplications for strain-engineering the electronic properties of graphene."
    },
    {
        "anchor": "Electron beam splitting at topological insulator surface states and a\n  proposal for electronic Goos-Hanchen shift measurement: The hexagonal warping effect on transport properties and Goos-H\\\"anchen (GH)\nlateral shift of electrons on the surface of a topological insulator with a\npotential barrier is investigated theoretically. Due to the warped Fermi\nsurface for incident electron beams, we can expect two propagating transmitted\nbeams corresponding to the occurrence of double refraction. The transmitted\nbeams have spin orientations locked to their momenta so one of the spin\ndirections rotates compared to the incident spin direction. Based on a\nlow-energy Hamiltonian near the Dirac point and considering Gaussian beams, we\nderive expressions for calculating lateral shifts in the presence of warping\neffect. We study the dependence of transmission probabilities and GH shifts of\ntransmitted beams on system parameters in detail by giving an explanation for\nthe appearance of large peaks in the lateral shifts corresponding to their\ntransmission peaks. It is shown that the separation between two transmitted\nbeams through their different GH shifts can be as large as a few micrometers,\nwhich is large enough to be observed experimentally. Finally, we propose a\nmethod to measure the GH shift of electron beams based on the transverse\nmagnetic focusing technique in which, by tuning an applied magnetic field, a\ndetectable resonant path for electrons can be induced.",
        "positive": "Voltage-controlled surface plasmon-polaritons in double graphene layer\n  structures: We study the spectra and damping of surface plasmon-polaritons in double\ngraphene layer structures. It is shown that application of bias voltage between\nlayers shifts the edge of plasmon absorption associated with the interband\ntransitions. This effect could be used in efficient plasmonic modulators. We\nreveal the influence of spatial dispersion of conductivity on plasmonic spectra\nand show that it results in the shift of cutoff frequency to the higher values."
    },
    {
        "anchor": "Is relaxation correlated in superconducting qubits?: We consider coupled quantum two-state systems (qubits) exposed to a global\nrelaxation process. The global relaxation refers to the assumption that qubits\nare coupled to the same quantum bath with approximately equal strengths,\nappropriate for long-wavelength environmental fluctuations. We show that\ninteractions do not spoil the picture of Dicke's subradiant and superradiant\nstates where quantum interference effects lead to striking deviations from the\nindependent relaxation picture. Remarkably, the system possess a stable\nentangled state and a state decaying faster than single qubit excitations. We\npropose a scheme how these effects can be experimentally accessed in\nsuperconducting flux qubits and, possibly, used in constructing long-lived\nentangled states.",
        "positive": "Towards quantum-limited coherent detection of terahertz waves in\n  charge-neutral graphene: Spectacular advances in heterodyne astronomy with both the Herschel Space\nObservatory and Stratospheric Observatory for Far Infrared Astronomy (SOFIA)\nhave been largely due to breakthroughs in detector technology. In order to\nexploit the full capacity of future THz telescope space missions (e.g. Origins\nSpace Telescope), new concepts of THz coherent receivers are needed, providing\nlarger bandwidths and imaging capabilities with multi-pixel focal plane\nheterodyne arrays. Here we show that graphene, uniformly doped to the Dirac\npoint, enables highly sensitive and wideband coherent detection of THz signals.\nWith material resistance dominated by quantum localization, and thermal\nrelaxation governed by electron diffusion, proof-of-concept graphene bolometers\ndemonstrate a gain bandwidth of 8 GHz and a mixer noise temperature of 475 K,\nlimited by residual thermal background in our setup. An optimized device will\nresult in a mixer noise temperature as low as 36 K, with the gain bandwidth\nexceeding 20 GHz, and a Local Oscillator power lower than 100 pW. In\nconjunction with the emerging quantum-limited amplifiers at the intermediate\nfrequency, our approach promises quantum-limited sensing in the THz domain,\npotentially surpassing superconducting technologies, particularly for large\nheterodyne arrays."
    },
    {
        "anchor": "Beating oscillation and Fano resonance in the laser assisted electron\n  transmission through graphene \u03b4- function magnetic barriers: We investigate theoretically the transmission of electrons through a pair of\n{\\delta}- function magnetic barriers in graphene in presence of external\nmonochromatic, linearly polarised and CW laser field. The transmission\ncoefficients are calculated in the framework of non-perturbative Floquet theory\nusing the transfer matrix method. It is noted that the usual Fabry-Perot\noscillations in transmission through the graphene magnetic barriers with larger\ninter barrier separation takes the shape of beating oscillations in presence of\nthe external laser field. The laser assisted transmission spectra are also\nfound to exhibit the characteristic Fano resonances (FR) for smaller values of\nthe inter barrier separation. The appearance of the perfect node in the beating\noscillation and the asymmetric Fano line shape can be controlled by varying the\nintensity of the laser field. The above features could provide some useful and\npotential information about the light - matter interactions and may be utilized\nin the graphene based optoelectronic device applications.",
        "positive": "Universal Model of Optical-Field Electron Tunneling from Two-Dimensional\n  Materials: We develop analytical models of optical-field electron tunneling from the\nedge and surface of two-dimensional (2D) materials, including the effects of\nreduced dimensionality, non-parabolic energy dispersion, band anisotropy,\nquasi-time dependent tunneling and emission dynamics indueced by the laser\nfield. We discover a universal scaling between the tunneling current density\n$J$ and the laser electric field $F$: In($J/|F|^{\\beta})\\propto1/|F|$ with\n$\\beta = 3 / 2$ in the edge emission and $\\beta = 1$ in the vertical surface\nemission, which both are distinctive from the traditional Fowler-Nordheim (FN)\nmodel of $\\beta = 2$. The current density exhibits an unexpected high-field\nsaturation effect due to the reduced dimensionality of 2D materials, which is\ncompletely different from the space-charge saturation commonly observed in\ntraditional bulk materials. Our results reveal the dc bias as an efficient\nmethod in modulating the optical-field tunneling sub-optical-cycle emission\ncharacteristics. Importantly, our model is in excellent agreement with a recent\nexperiment on graphene. Our findings offer a theoretical foundation for the\nunderstanding of optical-field tunneling emission from the 2D material system,\nwhich is useful for the development of 2D-material based optoelectronics and\nvacuum nanoelectronics."
    },
    {
        "anchor": "Emergence of broken-symmetry states at half-integer band fillings in\n  twisted bilayer graphene: The dominance of Coulomb interactions over kinetic energy of electrons in\nnarrow, non-trivial moir\\'{e} bands of magic-angle twisted bilayer graphene\n(TBG) gives rise to a variety of correlated phases such as correlated\ninsulators, superconductivity, orbital ferromagnetism, Chern insulators and\nnematicity. Most of these phases occur at or near an integer number of carriers\nper moir\\'{e} unit cell. Experimental demonstration of ordered states at\nfractional moir\\'{e} band-fillings at zero applied magnetic field $B$, is a\nchallenging pursuit. In this letter, we report the observation of states near\nhalf-integer band-fillings of $\\nu\\approx 0.5$ and $\\pm3.5$ at $B\\approx 0$ in\nTBG proximitized by tungsten diselenide (WSe$_2$) through magnetotransport and\nthermoelectricity measurements. A series of Lifshitz transitions due to the\nchanges in the topology of the Fermi surface implies the evolution of van Hove\nsingularities (VHSs) of the diverging density of states (DOS) at a discrete set\nof partial fillings of flat bands. Furthermore, at a band filling of\n$\\nu\\approx-0.5$, a symmetry-broken Chern insulator emerges at high $B$,\ncompatible with the band structure calculations within a translational\nsymmetry-broken supercell with twice the area of the original TBG moir\\'{e}\ncell. Our results are consistent with a spin/charge density wave ground state\nin TBG in the zero $B$-field limit.",
        "positive": "Quench Dynamics of Josephson Current in a Topological Josephson Junction: The $4\\pi$ Josephson Effect is a distinguishing feature of a topological\nJosephson junction. However, stringent conditions make it hard to observe in\nexperiments. Here we numerically study the transient transport properties in a\ntopological Josephson junction. We show that the $4\\pi$ Josephson current can\nbe sustained for a significant time (around several $\\mu s$ with suitable\nconditions). Furthermore, we compare the behaviors of Josephson current in\ndifferent conditions, identifying three main regimes: First, when both the\nsuperconducting wires of the Josephson junction lie in the topologically\nnontrivial region, the $4\\pi$ Josephson current can appear with a suddenly\napplied DC voltage. Second, when one superconducting wire lies in the trivial\nregion and the other one lies in the non-trivial region, the Josephson current\nis $2\\pi$ periodic but unstable with the evolving of time. Third, when both\nwires lie in the trivial region, a stable $2\\pi$ Josephson current is observed.\nThese results can facilitate fine-tuning of the experiment parameters in order\nto finally observe the $4\\pi$ Josephson current in a topological Josephson\njunction."
    },
    {
        "anchor": "Charged two-dimensional magnetoexciton and two-mode squeezed vacuum\n  states: A novel unitary transformation of the Hamiltonian that allows one to\npartially separate the center-of-mass motion for charged electron-hole systems\nin a magnetic field is presented. The two-mode squeezed oscillator states that\nappear at the intermediate stage of the transformation are used for\nconstructing a trial wave function of a two-dimensional (2D) charged\nmagnetoexciton.",
        "positive": "Quantum interference and supercurrent in multiple-barrier proximity\n  structures: We analyze an interplay between the proximity effect and quantum interference\nof electrons in hybrid structures superconductor-normal metal-superconductor\nwhich contain several insulating barriers. We demonstrate that the dc Josephson\ncurrent in these structures may change qualitatively due to quantum\ninterference of electrons scattered at different interfaces. In junctions with\nfew conducting channels mesoscopic fluctuations of the supercurrent are\nsignificant and its amplitude can be strongly enhanced due to resonant effects.\nIn the many channel limit averaging over the scattering phase effectively\nsuppresses interference effects for systems with {\\it two} insulating barriers.\nIn that case a standard quasiclassical approach describing scattering at\ninterfaces by means of Zaitsev boundary conditions allows to reproduce the\ncorrect results. However, in systems with {\\it three} or more barriers the\nlatter approach fails even in the many channel limit. In such systems\ninterference effects remain important in this limit as well. For short\njunctions these effects result in additional suppression of the Josephson\ncritical current indicating the tendency of the system towards localization.\nFor relatively long junctions interference effects may -- on the contrary --\nenhance the supercurrent with respect to the case of independent barriers."
    },
    {
        "anchor": "Effect of scattering and contacts on current and electrostatics in\n  carbon nanotubes: We computationally study the electrostatic potential profile and current\ncarrying capacity of carbon nanotubes as a function of length and diameter. Our\nstudy is based on solving the non equilibrium Green's function and Poisson\nequations self-consistently, including the effect of electron-phonon\nscattering. A transition from ballistic to diffusive regime of electron\ntransport with increase of applied bias is manifested by qualitative changes in\npotential profiles, differential conductance and electric field in a nanotube.\nIn the low bias ballistic limit, most of the applied voltage drop occurs near\nthe contacts. In addition, the electric field at the tube center increases\nproportionally with diameter. In contrast, at high biases, most of the applied\nvoltage drops across the nanotube, and the electric field at the tube center\ndecreases with increase in diameter. We find that the differential conductance\ncan increase or decrease with bias as a result of an interplay of nanotube\nlength, diameter and a quality factor of the contacts. From an application view\npoint, we find that the current carrying capacity of nanotubes increases with\nincrease in diameter. Finally, we investigate the role of inner tubes in\naffecting the current carried by the outermost tube of a multiwalled nanotube.",
        "positive": "Phonon superradiance and phonon laser effect in nanomagnets: We show that the theory of spin-phonon processes in paramagnetic solids must\ntake into account the coherent generation of phonons by the magnetic centers.\nThis effect should drastically enhance spin-phonon rates in nanoscale\nparamagnets and in crystals of molecular nanomagnets."
    },
    {
        "anchor": "Surface and Edge States in Topological Semi-metals: We study the topologically non-trivial semi-metals by means of the 6-band\nKane model. Existence of surface states is explicitly demonstrated by\ncalculating the LDOS on the material surface. In the strain free condition,\nsurface states are divided into two parts in the energy spectrum, one part is\nin the direct gap, the other part including the crossing point of surface state\nDirac cone is submerged in the valence band. We also show how uni-axial strain\ninduces an insulating band gap and raises the crossing point from the valence\nband into the band gap, making the system a true topological insulator. We\npredict existence of helical edge states and spin Hall effect in the thin film\ntopological semi-metals, which could be tested with future experiment. Disorder\nis found to significantly enhance the spin Hall effect in the valence band of\nthe thin films.",
        "positive": "One-way transport in laser-illuminated bilayer graphene: A Floquet\n  isolator: We explore the Floquet band-structure and electronic transport in\nlaser-illuminated bilayer graphene. By using a bias voltage perpendicular to\nthe graphene bilayer we show how to get one-way charge and valley transport\namong two unbiased leads. In contrast to quantum pumping, our proposal uses a\ndifferent mechanism based on generating a non-reciprocal bandstructure with a\nbuilt-in directionality. The Floquet states at one edge of a graphene layer\nbecome hybridized with the continuum on the other layer, and so the resulting\nbandstructure allows for one-way transport as in an \\textit{isolator}. Our\nproof-of-concept may serve as a building block for devices exploiting one-way\nstates."
    },
    {
        "anchor": "ODMR Of Impurity Centers Embedded In Silicon Microcavities: We present the findings of high efficient light absorption in self-assembled\nquantum wells (SQW) embedded in silicon microcavities that exhibit a\ndistributed feedback identified by the FIR transmission spectra. The excitonic\nnormal-mode coupling (NMC) is found to result in high efficient bound exciton\nphotoluminescence in the range of the Rabi splitting. The bound excitons at the\niron-boron pair and the erbium-related centers inserted in SQW are shown to\ncause giant exchange splitting of the center multiplets as a result of the\nstrong sp-d and sp-f mixing in the absence of the external magnetic field. The\nNMC regime is observed to reveal this exchange splitting in the angular\ndependencies of the transmission spectra measured in the range of the Rabi\nsplitting that are evidence of the ODMR of the trigonal iron-boron pairs and\ntrigonal erbium-related centers.",
        "positive": "Saving Moore's Law Down To 1nm Channels With Anisotropic Effective Mass: Scaling transistors' dimensions has been the thrust for the semiconductor\nindustry in the last 4 decades. However, scaling channel lengths beyond 10 nm\nhas become exceptionally challenging due to the direct tunneling between source\nand drain which degrades gate control, switching functionality, and worsens\npower dissipation. Fortunately, the emergence of novel classes of materials\nwith exotic properties in recent times has opened up new avenues in device\ndesign. Here, we show that by using channel materials with an anisotropic\neffective mass, the channel can be scaled down to 1nm and still provide an\nexcellent switching performance in both MOSFETs and TFETs. In the case of\nTFETs, a novel design has been proposed to take advantage of anisotropic mass\nin both ON- and OFF-state of the TFETs. Full-band atomistic quantum transport\nsimulations of phosphorene nanoribbon MOSFETs and TFETs based on the new design\nhave been performed as a proof."
    },
    {
        "anchor": "Magneto-transport in closed and open mesoscopic loop structures: A\n  review: Magneto-transport properties in closed and open loop structures are carefully\nreviewed within a tight-binding formalism. A novel mesoscopic phenomenon where\na non-vanishing current is observed in a conducting loop upon the application\nof an Aharonov-Bohm flux $\\phi$ and we explore its behavior in the aspects of\nquantum phase coherence, electron-electron correlation and disorder. The\nessential results are analyzed in three different parts. First, we examine the\nbehavior of persistent current in different branches of a zigzag carbon\nnanotube within a Hartree-Fock mean field approach using the second quantized\nformulation. The phase reversal of persistent current in several branches as a\nfunction of Hubbard interaction is found to exhibit interesting patterns. Our\nnumerical results suggest a filling-dependent metal-insulator transition in a\nzigzag carbon nanotube. Next, we address the behavior of persistent current in\nan ordered-disordered separated nanotube keeping in mind a possible\nexperimental realization of shell-doped nanowire which can provide a strange\nelectronic behavior rather than uniformly doped nanowires. Finally, we focus\nour attention on the behavior of persistent current in an open loop geometry\nwhere we clamp an ordered binary alloy ring between two ideal semi-infinite\nelectrodes to make an electrode-ring-electrode bridge. From our investigation\nwe propose that under suitable choices of the parameter values the system can\nact as a $p$-type or an $n$-type semiconductor.",
        "positive": "Gyrotropic elastic response of skyrmion crystals to current-induced\n  tensions: We theoretically study the dynamics of skyrmion crystals in\nelectrically-insulating chiral magnets subjected to current-induced spin\ntorques by adjacent metallic layers. We develop an elasticity theory that\naccounts for the gyrotropic force engendered by the non-trivial topology of the\nspin texture, tensions at the boundaries due to the exchange of linear and spin\nangular momentum with the metallic reservoirs, and dissipation in the bulk of\nthe film. A steady translation of the skyrmion crystal is triggered by the\ncurrent-induced tensions and subsequently sustained by dissipative forces,\ngenerating an electromotive force on itinerant spins in the metals. This\nphenomenon should be revealed as a negative drag in an open two-terminal\ngeometry, or equivalently, as a positive magnetoresistance when the terminals\nare connected in parallel. We propose non-local transport measurements with\nthese salient features as a tool to characterize the phase diagram of\ninsulating chiral magnets."
    },
    {
        "anchor": "Spin-current vortices in current-perpendicular-to-plane nanoconstricted\n  spin-valves: The charge and spin diffusion equations taking into account spin-flip and\nspin-transfer torque were numerically solved using a finite element method in\ncomplex non-collinear geometry with strongly inhomogeneous current flow. As an\nillustration, spin-dependent transport through a non-magnetic nanoconstriction\nseparating two magnetic layers was investigated. Unexpected results such as\nvortices of spin-currents in the vicinity of the nanoconstriction were\nobtained. The angular variations of magnetoresistance and spin-transfer torque\nare strongly influenced by the structure geometry.",
        "positive": "Nanomechanics of CNTs for Sensor Application: A nanoscopic simulation for an acceleration sensor is aimed based on the\npiezoresistive effect of carbon nanotubes (CNTs). Therefore, a compact model is\nbuilt from density functional theory (DFT), compared with results of molecular\ndynamics (MD) that describes the mechanics of carbon nanotubes in a\nparameterized way. The results for the interesting kind of CNTs [(6,3) and\n(7,4)] within the two approaches agree in a satisfying way, when\nDFT-calculations are performed with atomic configurations obtained by MD\ngeometry optimization. Geometry optimization yields the Poisson ratio for CNTs.\nThus, values from MD and DFT are compared. The simulation finally aims the\nmodeling of the conductive behavior of CNTs when strain is applied, but this\nneeds further verification. Here, we present the prediction of the tight\nbinding model for suitable CNTs."
    },
    {
        "anchor": "Vortex-enabled Andreev processes in quantum Hall-superconductor hybrids: Quantum Hall-superconductor heterostructures provide possible platforms for\nintrinsically fault-tolerant quantum computing. Motivated by several recent\nexperiments that successfully integrated these phases, we investigate transport\nthrough a proximitized integer quantum Hall edge--paying particular attention\nto the impact of vortices in the superconductor. By examining the downstream\nconductance, we identify regimes in which sub-gap vortex levels mediate Andreev\nprocesses that would otherwise be frozen out in a vortex-free setup. Moreover,\nwe show that at finite temperature, and in the limit of a large number of\nvortices, the downstream conductance can average to zero, indicating that the\nsuperconductor effectively behaves like a normal contact. Our results highlight\nthe importance of considering vortices when using transport measurements to\nstudy superconducting correlations in quantum Hall-superconductor hybrids.",
        "positive": "Numerically exact, time-dependent treatment of vibrationally coupled\n  electron transport in single-molecule junctions: The multilayer multiconfiguration time-dependent Hartree (ML-MCTDH) theory\nwithin second quantization representation of the Fock space, a novel\nnumerically exact methodology to treat many-body quantum dynamics for systems\ncontaining identical particles, is applied to study the effect of vibrational\nmotion on electron transport in a generic model for single-molecule junctions.\nThe results demonstrate the importance of electronic-vibrational coupling for\nthe transport characteristics. For situations where the energy of the bridge\nstate is located close to the Fermi energy, the simulations show the\ntime-dependent formation of a polaron state that results in a pronounced\nsuppression of the current corresponding to the phenomenon of phonon blockade.\nWe show that this phenomenon cannot be explained solely by the polaron shift of\nthe energy but requires methods that incorporate the dynamical effect of the\nvibrations on the transport. The accurate results obtained with the ML-MCTDH in\nthis parameter regime are compared to results of nonequilibrium Green's\nfunction (NEGF) theory."
    },
    {
        "anchor": "Lagrangian and impedance spectroscopy treatments of electric force\n  microscopy: Scanning probe microscopy is often extended beyond topographic imaging to\nstudy electrical forces and sample properties, with the most widely used\nexperiment being frequency-modulated Kelvin probe force microscopy. The\nequations commonly used to interpret this experiment, however, rely on two\nhidden assumptions: (1) the tip charge oscillates in phase with the cantilever\nmotion to keep the tip voltage constant, and (2) any changes in the tip-sample\ninteraction happen slowly. Starting from an electro-mechanical model of the\ncantilever-sample interaction, we use Lagrangian mechanics to derive coupled\nequations of motion for the cantilever position and charge. This general\napproach rigorously describes scanned probe experiments even in the case when\nthe usual assumptions of fast tip charging and slowly changing samples\nproperties are violated. We develop a Magnus-expansion approximation to\nillustrate how abrupt changes in the tip-sample interaction cause abrupt\nchanges in the cantilever amplitude and phase. We show that feedback-free\ntime-resolved electric force microscopy cannot uniquely determine sub-cycle\nphotocapacitance dynamics. We then use first-order perturbation theory to\nrelate cantilever frequency shift and dissipation to the sample impedance even\nwhen the tip charge oscillates out of phase with the cantilever motion.\nAnalogous to the treatment of impedance spectroscopy in electrochemistry, we\napply this approximation to determine the cantilever frequency shift and\ndissipation for an arbitrary sample impedance in (broadband) local dielectric\nspectroscopy experiments. The general approaches we develop provide a path\nforward for rigorously modeling the coupled motion of the cantilever position\nand charge in the wide range of electrical scanned probe microscopy experiments\nwhere the hidden assumptions of the conventional equations are violated or\ninapplicable.",
        "positive": "Strong magnetoresistance in a graphene Corbino disk at low magnetic\n  fields: We have measured magnetoresistance of suspended graphene in the Corbino\ngeometry at magnetic fields up to $B=0.15\\,$T, i.e., in a regime uninfluenced\nby Shubnikov-de Haas oscillations. The low-temperature relative\nmagnetotoresistance $[R(B)-R(0)]/R(0)$ amounts to $4000 B^2\\% $ at the Dirac\npoint ($B$ in Tesla), with a quite weak temperature dependence below $30\\,$K. A\ndecrease in the relative magnetoresistance by a factor of two is found when\ncharge carrier density is increased to $|n| \\simeq 3 \\times 10^{-10}$\ncm$^{-2}$. The gate dependence of the magnetoresistance allows us to\ncharacterize the role of scattering on long-range (Coulomb impurities, ripples)\nand short-range potential, as well as to separate the bulk resistance from the\ncontact one. Furthermore, we find a shift in the position of the charge\nneutrality point with increasing magnetic field, which suggests that magnetic\nfield changes the screening of Coulomb impurities around the Dirac point. The\ncurrent noise of our device amounts to $10^{-23}$ A$^2$/$\\sqrt{\\textrm{Hz}}$ at\n$1\\,$kHz at $4\\,$K, which corresponds to a magnetic field sensitivity of $60$\nnT/$\\sqrt{\\textrm{Hz}}$ in a background field of $0.15\\,$T."
    },
    {
        "anchor": "Effects of Dzyaloshinsky-Moriya Interaction on magnetism in Nanodisks: We give a theoretical study on the magnetic properties of monolayer nanodisks\nwith both Heisenberg exchange and Dzyaloshinsky-Moriya (DM) interactions. In\nparticular, we survey the magnetic effects caused by anisotropy, external\nmagnetic field, and disk size when DM interaction is present by means of a new\nquantum simulation method based on mean-field theory. This computational\napproach finds that uniaxial anisotropy and transverse magnetic field enhances\nthe net magnetization as well as increases the transition temperature of the\nvortex phase while preserving the chiralities of the nanodisks. Whereas, when\nthe strength of DM interaction is sufficiently strong for a given disk size,\nmagnetic domains appear within the circularly bounded region, which vanish and\ngives in to a single vortex when a transverse magnetic field is applied. The\nlatter confirms the magnetic skyrmions induced by the magnetic field as\nobserved in the experiments.",
        "positive": "Facile fabrication of lateral nanowire wrap-gate devices with improved\n  performance: We present a simple fabrication technique for lateral nanowire wrap-gate\ndevices with high capacitive coupling and field-effect mobility. Our process\nuses e-beam lithography with a single resist-spinning step, and does not\nrequire chemical etching. We measure, in the temperature range 1.5-250 K, a\nsubthreshold slope of 5-54 mV/decade and mobility of 2800-2500 $cm^2/Vs$ --\nsignificantly larger than previously reported lateral wrap-gate devices. At\ndepletion, the barrier height due to the gated region is proportional to\napplied wrap-gate voltage."
    },
    {
        "anchor": "Anomalous galvanomagnetism, cyclotron resonance and microwave\n  spectroscopy of topological insulators: The surface quantum Hall state, magneto-electric phenomena and their\nconnection to axion electrodynamics have been studied intensively for\ntopological insulators. One of the obstacles for observing such effects comes\nfrom nonzero conductivity of the bulk. To overcome this obstacle we propose to\nuse an external magnetic field to suppress the conductivity of the bulk\ncarriers. The magnetic field dependence of galvanomagnetic and electromagnetic\nresponses of the whole system shows anomalies due to broken time-reversal\nsymmetry of the surface quantum Hall state, which can be used for its\ndetection. In particular, we find linear bulk dc magnetoresistivity and a\nquadratic field dependence of the Hall angle, shifted rf cyclotron resonance,\nnonanalytic microwave transmission coefficient and saturation of the Faraday\nrotation angle with increasing magnetic field or wave frequency.",
        "positive": "Disorder-induced zero-bias peaks in Majorana nanowires: Focusing specifically on the recently retracted Nature 2018 Zhang et al. work\n[Zhang et al., Nature (2021)] and the related recently available correctly\nanalyzed data from this Delft experiment [Zhang et al., arXiv:2101.11456\n(2021)], we discuss the general problem of confirmation bias in experiments\nverifying various theoretical topological quantization predictions. We show\nthat the Delft Majorana experiment is most likely dominated by disorder, which\nproduces trivial (but quite sharp and large) zero-bias Andreev tunneling peaks\nwith large conductance $ \\sim 2e^2/h $ in the theory, closely mimicking the\ndata. It is possible to misinterpret such disorder-induced zero-bias trivial\npeaks as the apparent Majorana quantization, as was originally done in 2018\narising from confirmation bias. One characteristic of the disorder-induced\ntrivial peaks is that they manifest little stability as a function of Zeeman\nfield and tunnel barrier, distinguishing their trivial behavior from the\nexpected topological robustness of non-Abelian Majorana zero modes. We also\nanalyze a more recent nanowire experiment [Yu et al., Nature Physics (2021)]\nwhich is known to have a huge amount of disorder, showing that such highly\ndisordered nanowires may produce very small above-background trivial peaks with\nvalues $ \\sim 2e^2/h $."
    },
    {
        "anchor": "Self-assembled chains of graphitized carbon nanoparticles: We report a technique which allows self-assembly of conducting nanoparticles\ninto long continuous chains. Transport properties of such chains have been\nstudied at low temperatures. At low bias voltages, the charges are pinned and\nthe chain resistance is exponentially high. Above a certain threshold\n($V_{T}$), the system enters a conducting state. The threshold voltage is much\nbigger than the Coulomb gap voltage for a single particle and decreases\nlinearly with increasing temperature. A sharp threshold was observed up to\nabout 77 K. Such chains may be used as switchable links in Coulomb charge\nmemories.",
        "positive": "Fractional Quantum Hall Effect in Hofstadter Butterflies of Dirac\n  Fermions: We report on the influence of a periodic potential on the fractional quantum\nHall effect (FQHE) states in monolayer graphene. We have shown that for two\nvalues of the magnetic flux per unit cell (one-half and one-third flux quantum)\nan increase of the periodic potential strength results in a closure of the FQHE\ngap and appearance of gaps due to the periodic potential. In the case of\none-half flux quantum this causes a change of the ground state and consequently\nthe change of the momentum of the system in the ground state. While there is\nalso crossing between low-lying energy levels for one-third flux quantum the\nground state does not change with the increase of the periodic potential\nstrength and is always characterized by the same momentum. Finally, it is shown\nthat for one-half flux quantum the emergent gaps are due entirely to the\nelectron-electron interaction, whereas for the one-third flux quantum per unit\ncell these are due to both non-interacting electrons (Hofstadter butterfly\npattern) and the electron-electron interaction."
    },
    {
        "anchor": "Transport across a topoelectrical Weyl semimetal heterojunction: We propose a general method to realize and calculate the transmission in a\nWeyl semimetal (WSM) heterostructure by employing a periodic three-dimensional\ntopoelectrical (TE) circuit network. By drawing the analogy between\ninductor-capacitor circuit lattices and quantum mechanical tight-binding (TB)\nmodels, we show that the energy flux in a TE network is analogous to the\nprobability flux in a TB Hamiltonian. TE systems offer a key advantage in that\nthey can be easily tuned to achieve different topological WSM phases simply by\nvarying the capacitances and inductances. The above analogy opens the way to\nthe study of tunneling across heterojunctions separating different types of\nWSMs in TE circuits, a situation which is virtually impossible to realize in\nphysical WSM materials. We show that the energy flux transmission in a WSM\nheterostructure depends highly on the relative orientation of the transport\ndirection and the $k$-space tilt direction. For the transmission from a Type I\nWSM source lead to a Type II WSM drain lead, all valleys transmit equally when\nthe tilt and transmission directions are perpendicular to each other. In\ncontrast, large inter-valley scattering is required for transmission when the\ntilt and transport directions are parallel to each other, leading to\nvalley-dependent transmission. We describe a Type III WSM phase intermediate\nbetween the Type I and Type II phases. An `anti-Klein' tunneling occurs between\na Type I source and Type III drain where the transmission is totally suppressed\nfor some valleys at normal incidence. This is in direct contrast to the usual\nKlein tunneling in Dirac materials where normally incident flux is perfectly\ntransmitted. Owing to the ease of fabrication and experimental accessibility,\nTE circuits offer an excellent testbed to study the extraordinary transport\nphenomena in WSM based heterostructures.",
        "positive": "Nonideal quantum detectors in Bayesian formalism: The Bayesian formalism for a continuous measurement of solid-state qubits is\nderived for a model which takes into account several factors of the detector\nnonideality. In particular, we consider additional classical output and\nbackaction noises (with finite correlation), together with quantum-limited\noutput and backaction noises, and take into account possible asymmetry of the\ndetector coupling. The formalism is first derived for a single qubit and then\ngeneralized to the measurement of entangled qubits."
    },
    {
        "anchor": "Quantum Hall system in Tao-Thouless limit: We consider spin-polarized electrons in a single Landau level on a torus. The\nquantum Hall problem is mapped onto a one-dimensional lattice model with\nlattice constant $2\\pi/L_1$, where $L_1$ is a circumference of the torus (in\nunits of the magnetic length). In the Tao-Thouless limit, $L_1\\to 0$, the\ninteracting many-electron problem is exactly diagonalized at any rational\nfilling factor $\\nu=p/q\\le 1$. For odd $q$, the ground state has the same\nqualitative properties as a bulk ($L_1 \\to \\infty$) quantum Hall hierarchy\nstate and the lowest energy quasiparticle exitations have the same fractional\ncharges as in the bulk. These states are the $L_1 \\to 0$ limits of the\nLaughlin/Jain wave functions for filling fractions where these exist. We argue\nthat the exact solutions generically, for odd $q$, are continuously connected\nto the two-dimensional bulk quantum Hall hierarchy states, {\\it ie} that there\nis no phase transition as $L_1 \\to \\infty$ for filling factors where such\nstates can be observed. For even denominator fractions, a phase transition\noccurs as $L_1$ increases. For $\\nu=1/2$ this leads to the system being mapped\nonto a Luttinger liquid of neutral particles at small but finite $L_1$, this\nthen develops continuously into the composite fermion wave function that is\nbelieved to describe the bulk $\\nu=1/2$ system. The analysis generalizes to\nnon-abelian quantum Hall states.",
        "positive": "3D Cavity quantum electrodynamics with a rare-earth spin ensemble: We present cavity QED experiments with an Er:YSO crystal magnetically coupled\nto a 3D cylindrical sapphire loaded copper resonator. Such waveguide cavities\nare promising for the realization of a superconducting quantum processor. Here,\nwe demonstrate the coherent integration of a rare-earth spin ensemble with the\n3D architecture. The collective coupling strength of the Er$^{3+}$ spins to the\n3D cavity is 21 MHz. The cylindrical sapphire loaded resonator allowed us to\nexplore the anisotropic collective coupling between the rare-earth doped\ncrystal and the cavity. This work shows the potential of spin doped solids in\n3D quantum circuits for application as microwave quantum memories as well as\nfor prospective microwave to optical interfaces."
    },
    {
        "anchor": "Robust Majorana conductance peaks for a superconducting lead: Experimental evidence for Majorana bound states largely relies on\nmeasurements of the tunneling conductance. While the conductance into a\nMajorana state is in principle quantized to $2e^2/h$, observation of this\nquantization has been elusive, presumably due to temperature broadening in the\nnormal-metal lead. Here, we propose to use a superconducting lead instead,\nwhose gap strongly suppresses thermal excitations. For a wide range of\ntunneling strengths and temperatures, a Majorana state is then signaled by\nsymmetric conductance peaks at $eV=\\pm\\Delta$ with quantized height\n$G=(4-\\pi)2e^2/h$. For a superconducting scanning tunneling microscope tip,\nMajorana states appear as spatial conductance plateaus while the conductance\nvaries with the local wavefunction for trivial Andreev bound states. We discuss\neffects of nonresonant (bulk) Andreev reflections and quasiparticle poisoning.",
        "positive": "Full counting statistics and conditional evolution in a\n  nanoelectromechanical system: We study theoretically the full distribution of transferred charge in a\ntunnel junction (or quantum point contact) coupled to a nanomechanical\noscillator, as well as the conditional evolution of the oscillator. Even if the\noscillator is very weakly coupled to the tunnel junction, it can strongly\naffect the tunneling statistics and lead to a highly non-Gaussian distribution.\nConversely, given a particular measurement history of the current, the\noscillator energy distribution may be localized and highly non-thermal. We also\ndiscuss non-Gaussian correlations between the oscillator motion and tunneling\nelectrons; these show that the tunneling back-action cannot be fully described\nas an effective thermal bath coupled to the oscillator."
    },
    {
        "anchor": "Universal Platform for Scalable Semiconductor-Superconductor Nanowire\n  Networks: Semiconductor-superconductor hybrids are commonly used in research on\ntopological quantum computation. Traditionally, top-down approaches involving\ndry or wet etching are used to define the device geometry. These often\naggressive processes risk causing damage to material surfaces, giving rise to\nscattering sites particularly problematic for quantum applications. Here, we\npropose a method that maintains the flexibility and scalability of selective\narea grown nanowire networks while omitting the necessity of etching to create\nhybrid segments. Instead, it takes advantage of directional growth methods and\nuses bottom-up grown InP structures as shadowing objects to obtain selective\nmetal deposition. The ability to lithographically define the position and area\nof these objects, and to grow a predefined height, ensures precise control of\nthe shadowed region. We demonstrate the approach by growing InSb nanowire\nnetworks with well-defined Al and Pb islands. Cross-section cuts of the\nnanowires reveal a sharp, oxide-free interface between semiconductor and\nsuperconductor. By growing InP structures on both sides of in-plane nanowires,\na combination of Pt and Pb can independently be shadow deposited, enabling a\nscalable and reproducible in-situ device fabrication. The\nsemiconductor-superconductor nanostructures resulting from this approach are at\nthe forefront of material development for Majorana based experiments.",
        "positive": "Electron transport in a one dimensional conductor with inelastic\n  scattering by self-consistent reservoirs: We present an extension of the work of D'Amato and Pastawski on electron\ntransport in a one-dimensional conductor modeled by the tight binding lattice\nHamiltonian and in which inelastic scattering is incorporated by connecting\neach site of the lattice to one-dimensional leads. This model incorporates\nB\\\"uttiker's original idea of dephasing probes. Here we consider finite\ntemperatures and study both electrical and heat transport across a chain with\napplied chemical potential and temperature gradients. Our approach involves\nquantum Langevin equations and nonequilibrium Green's functions. In the linear\nresponse limit we are able to solve the model exactly and obtain expressions\nfor various transport coefficients. Standard linear response relations are\nshown to be valid. We also explicitly compute the heat dissipation and show\nthat for wires of length $N >> \\ell$, where $\\ell$ is a coherence length scale,\ndissipation takes place uniformly along the wire. For $N << \\ell$, when\ntransport is ballistic, dissipation is mostly at the contacts. In the\nintermediate range between Ohmic and ballistic transport we find that the\nchemical potential profile is linear in the bulk with sharp jumps at the\nboundaries. These are explained using a simple model where the left and right\nmoving electrons behave as persistent random walkers."
    },
    {
        "anchor": "Gate Tunable Josephson Diode in Proximitized InAs Supercurrent\n  Interferometers: The Josephson diode (JD) is a non-reciprocal circuit element that supports a\nlarger critical current in one direction compared to the other. This effect has\ngained a growing interest because of promising applications in superconducting\nelectronic circuits with low power consumption. Some implementations of a JD\nrely on breaking the inversion symmetry in the material used to realize\nJosephson junctions (JJs), but two recent theoretical proposals have suggested\nthat the effect can also be engineered by combining two JJs hosting highly\ntransmitting Andreev bound states in a Superconducting Quantum Interference\nDevice (SQUID) at a small, but finite flux bias [1, 2]. We have realized a\nSQUID with two JJs fabricated in a proximitized InAs two-dimensional electron\ngas (2DEG). We demonstrate gate control of the diode efficiency from zero up to\naround 30% at specific flux bias values which comes close to the maximum of\napproxiomately 40% predicated in Ref. [1]. The key ingredients to the JD effect\nin the SQUID arrangement is the presence of highly transmitting channels in the\nJJs, a flux bias and an asymmetry between the two SQUID arms.",
        "positive": "Field emission properties of as-grown multiwalled carbon nanotube films: Multiwalled carbon nanotubes have been produced by ethylene catalytic\nchemical vapor deposition and used to fabricate thick and dense freestanding\nfilms (\"buckypapers\") by membrane filtering. Field emission properties of\nbuckypapers have been locally studied by means of high vacuum atomic force\nmicroscopy with a standard metallic cantilever used as anode to collect\nelectrons emitted from the sample. Buckypapers showed an interesting linear\ndependence in the Fowler-Nordheim plots demonstrating their suitability as\nemitters. By precisely tuning the tip-sample distance in the submicron region\nwe found out that the field enhancement factor is not affected by distance\nvariations up to 2um. Finally, the study of current stability showed that the\nfield emission current with intensity of about 3,3*10-5A remains remarkably\nstable (within 5% fluctuations) for several hours."
    },
    {
        "anchor": "Coulomb drag between ballistic one-dimensional electron systems: The presence of pronounced electronic correlations in one-dimensional systems\nstrongly enhances Coulomb coupling and is expected to result in distinctive\nfeatures in the Coulomb drag between them that are absent in the drag between\ntwo-dimensional systems. We review recent Fermi and Luttinger liquid theories\nof Coulomb drag between ballistic one-dimensional electron systems, and give a\nbrief summary of the experimental work reported so far on one-dimensional drag.\nBoth the Fermi liquid (FL) and the Luttinger liquid (LL) theory predict a\nmaximum of the drag resistance R_D when the one-dimensional subbands of the two\nquantum wires are aligned and the Fermi wave vector k_F is small, and also an\nexponential decay of R_D with increasing inter-wire separation, both features\nconfirmed by experimental observations. A crucial difference between the two\ntheoretical models emerges in the temperature dependence of the drag effect.\nWhereas the FL theory predicts a linear temperature dependence, the LL theory\npromises a rich and varied dependence on temperature depending on the relative\nmagnitudes of the energy and length scales of the systems. At higher\ntemperatures, the drag should show a power-law dependence on temperature, $R_D\n\\~ T^x$, experimentally confirmed in a narrow temperature range, where x is\ndetermined by the Luttinger liquid parameters. The spin degree of freedom plays\nan important role in the LL theory in predicting the features of the drag\neffect and is crucial for the interpretation of experimental results.",
        "positive": "Knight shift and nuclear spin relaxation in Fe/n-GaAs heterostructures: We investigate the dynamically polarized nuclear-spin system in\nFe/\\emph{n}-GaAs heterostructures using the response of the electron-spin\nsystem to nuclear magnetic resonance (NMR) in lateral spin-valve devices. The\nhyperfine interaction is known to act more strongly on donor-bound electron\nstates than on those in the conduction band. We provide a quantitative model of\nthe temperature dependence of the occupation of donor sites. With this model we\ncalculate the ratios of the hyperfine and quadrupolar nuclear relaxation rates\nof each isotope. For all temperatures measured, quadrupolar relaxation limits\nthe spatial extent of nuclear spin-polarization to within a Bohr radius of the\ndonor sites and is directly responsible for the isotope dependence of the\nmeasured NMR signal amplitude. The hyperfine interaction is also responsible\nfor the $2\\text{ kHz}$ Knight shift of the nuclear resonance frequency that is\nmeasured as a function of the electron spin accumulation. The Knight shift is\nshown to provide a measurement of the electron spin-polarization that agrees\nqualitatively with standard spin transport measurements."
    },
    {
        "anchor": "Zeeman splitting of interacting two-dimensional electrons with two\n  effective masses: We have realized an AlAs two-dimensional electron system in which electrons\noccupy conduction-band valleys with different Fermi contours and effective\nmasses. In the quantum Hall regime, we observe both resistivity spikes and\npersistent gaps at crossings between the Landau levels originating from these\ntwo valleys. From the positions of the spikes in tilted magnetic field and\nmeasurements of the energy gaps away from the crossings, we find that, after\noccupation of the minority valley, the spin susceptibility drops rapidly, and\nthe electrons possess a {\\it single} interaction-enhanced g-factor, despite the\ndissimilarity of the two occupied valleys.",
        "positive": "Tunable hole spin-photon interaction based on g-matrix modulation: We consider a spin circuit-QED device where a superconducting microwave\nresonator is capacitively coupled to a single hole confined in a semiconductor\nquantum dot. Thanks to the strong spin-orbit coupling intrinsic to valence-band\nstates, the gyromagnetic g-matrix of the hole can be modulated electrically.\nThis modulation couples the photons in the resonator to the hole spin. We show\nthat the applied gate voltages and the magnetic-field orientation enable a\nversatile control of the spin-photon interaction, whose character can be\nswitched from fully transverse to fully longitudinal. The longitudinal coupling\nis actually maximal when the transverse one vanishes and vice-versa. This\n\"reciprocal sweetness\" results from geometrical properties of the g-matrix and\nprotects the spin against dephasing or relaxation. We estimate coupling rates\nreaching ~ 10 MHz in realistic settings and discuss potential circuit-QED\napplications harnessing either the transverse or the longitudinal spin-photon\ninteraction. Furthermore, we demonstrate that the g-matrix curvature can be\nused to achieve parametric longitudinal coupling with enhanced coherence."
    },
    {
        "anchor": "Charge-Transfer Chemical Reactions in Nanofluidic Fabry-P{\u00e9}rot\n  Cavities: We investigate the chemical reactivity of molecular populations confined\ninside a nanofluidic Fabry-P{\\'e}rot cavity. Due to strong light-matter\ninteractions developing between a resonant electromagnetic cavity-mode and the\nelectric dipole moment of the confined molecules, a polariton is formed. The\nformer gets dressed by environmental vibrational and rotational degrees of\nfreedom of the solvent. We call the resulting polariton dressed by its cloud of\nenvironmental excitation a ''reacton'', since it further undergoes chemical\nreactions. We characterize how the reacton formation modifies the kinetics of a\nphotoisomerization chemical reaction involving an elementary charge-transfer\nprocess. We show that the reaction driving-force and reorganization energy are\nboth modulated optically by the reactant concentration, the vacuum Rabi\nsplitting and the de-tuning between the Fabry-P{\\'e}rot cavity frequency and\ntargeted electronic transition. Finally, we compute the ultrafast picosecond\ndynamics of the whole photochemical reaction. We predict that despite optical\ncavity losses and solvent-mediated non-radiative relaxation, measurable\nsignatures of the reacton formation can be found in state-of-the-art pump-probe\nexperiments.",
        "positive": "Time-domain stability of parametric synchronization in a spin-torque\n  nano-oscillator based on a magnetic tunnel junction: We report on a time-domain study of parametric synchronization in a magnetic\ntunnel junction based spin torque nano-oscillator (STNO). Time-domain\nmeasurements of the instantaneous frequency ($f_{i}$) of a parametrically\nsynchronized STNO show random short-term unlocking of the STNO signal for low\ninjected radio-frequency (RF) power, which cannot be revealed in time-averaged\nfrequency domain measurements. Macrospin simulations reproduce the experimental\nresults and reveal that the random unlocking during synchronization is driven\nby thermal fluctuations. We show that by using a high injected RF power, random\nunlocking of the STNO can be avoided. However, a perfect synchronization\ncharacterized by complete suppression of phase noise, so-called phase noise\nsqueezing, can be obtained only at a significantly higher RF power. Our\nmacrospin simulations suggest that a lower temperature and a higher positive\nratio of the field-like torque to the spin transfer torque reduce the threshold\nRF power required for phase noise squeezing under parametric synchronization."
    },
    {
        "anchor": "First Principles Study of the Optical Dipole Trap for Two-Dimensional\n  Excitons in Graphane: Recent studies on excitons in two-dimensional materials have been widely\nconducted for their potential usages for novel electronic and optical devices.\nEspecially, sophisticated manipulation techniques of quantum degrees of freedom\nof excitons are demanded. In this paper we propose a technique of forming an\noptical dipole trap for excitons in graphane, a two-dimensional wide gap\nsemiconductor, based on first principles calculations. We develop a first\nprinciples method to evaluate the exciton transition dipole matrix and combine\nit with the density functional theory and GW+BSE calculations. We reveal that\nin graphane the huge exciton binding energy and the large dipole moments of\nWannier-like excitons enable us to induce the dipole trap of the order of meV\ndepth and $\\mu$m width. This work opens a new way to control light-exciton\ninteracting systems based on a newly developed numerically robust ab initio\ncalculations.",
        "positive": "Comment on: \"Microwave response of a two-dimensional electron stripe\",\n  cond-mat/0407364: Recently, S.A.Mikhailov et al presented a theoretical study(cond-mat/0407364)\nconcerning the electromagnetic response of a finite-width two-dimensional\nelectron stripe. Surprisingly, in the above manuscript the magnetic field\ndependence of the magnetoplasmon spectrum(namely Fig.4) reproduces that\nreported for the first time in our paper(cond-mat/0405176, JETP Lett., 80,\nAugust 2004, in press). We believe that the above curious coincidence may\nresult from the authors not to be informed enough."
    },
    {
        "anchor": "Electronic depth profiles with atomic layer resolution from resonant\n  soft x-ray reflectivity: The analysis of x-ray reflectivity data from artificial heterostructures\nusually relies on the homogeneity of optical properties of the constituent\nmaterials. However, when the x-ray energy is tuned to an absorption edge, this\nhomogeneity no longer exists. Within the same material, spatial regions\ncontaining elements at resonance will have optical properties very different\nfrom regions without resonating sites. In this situation, models assuming\nhomogeneous optical properties throughout the material can fail to describe the\nreflectivity adequately. As we show here, resonant soft x-ray reflectivity is\nsensitive to these variations, even though the wavelength is typically large as\ncompared to the atomic distances over which the optical properties vary. We\nhave therefore developed a scheme for analyzing resonant soft x-ray\nreflectivity data, which takes the atomic structure of a material into account\nby \"slicing\" it into atomic planes with characteristic optical properties.\nUsing LaSrMnO4 as an example, we discuss both the theoretical and experimental\nimplications of this approach. Our analysis not only allows to determine\nimportant structural information such as interface terminations and stacking of\natomic layers, but also enables to extract depth-resolved spectroscopic\ninformation with atomic resolution, thus enhancing the capability of the\ntechnique to study emergent phenomena at surfaces and interfaces.",
        "positive": "Non-Equilibrium RKKY Interaction in Irradiated Graphene: We demonstrate that the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction in\ngraphene can be strongly modified by a time-periodic driving field even in the\nweak drive regime. This effect is due to the opening of a dynamical band gap at\nthe Dirac points when graphene is exposed to circularly polarized light. Using\nKeldysh-Floquet Green's functions, we develop a theoretical framework to\ncalculate the time-averaged RKKY coupling under weak periodic drives and show\nthat its magnitude in undoped graphene can be decreased controllably by\nincreasing the driving strength, while mostly maintaining its ferromagnetic or\nantiferromagnetic character. In doped graphene, we find RKKY oscillations with\na period that is tunable by the driving field. When a sufficiently strong drive\nis turned on that brings the Fermi level completely within the dynamically\nopened gap, the behavior of the RKKY coupling changes qualitatively from that\nof doped to undoped irradiated graphene."
    },
    {
        "anchor": "Superconducting Spintronics: Traditional studies that combine spintronics and superconductivity have\nmainly focused on the injection of spin-polarized quasiparticles into\nsuperconducting materials. However, a complete synergy between superconducting\nand magnetic orders turns out to be possible through the creation of\nspin-triplet Cooper pairs, which are generated at carefully engineered\nsuperconductor interfaces with ferromagnetic materials. Currently, there is\nintense activity focused on identifying materials combinations that merge\nsuperconductivity and spintronics to enhance device functionality and\nperformance. The results look promising: it has been shown, for example, that\nsuperconducting order can greatly enhance central effects in spintronics such\nas spin injection and magnetoresistance. Here, we review the experimental and\ntheoretical advances in this field and provide an outlook for upcoming\nchallenges in superconducting spintronics.",
        "positive": "Realization of a vortex in the Kekule texture of molecular Graphene, at\n  a Y junction where 3 domains meet: Following the recent realization of an artificial version of Graphene in the\nelectronic surface states of copper with judiciously placed carbon monoxide\nmolecules inducing the honeycomb lattice symmetry (K. K. Gomes et al., Nature\n483, 306 (2012)), we demonstrate that these can be used to realize a vortex in\na Kekule texture of the honeycomb lattice. The Kekule texture is mathematically\nanalogous to a superconducting order parameter, opening a spectral gap in the\nmassless Dirac point spectrum of the Graphene structure. The core of a vortex\nin the texture order parameter, supports subgap states, which for this system\nare analogs of Majorana fermions in some superconducting states. In particular,\nthe electron charge bound to a single vortex core is effectively fractionalized\nto a charge of $e/2$. The Kekule texture as realized in the molecular Graphene\nsystem realizes 3 different domain types, and we show that a Y-junction between\nthem realizes the coveted Kekule vortex."
    },
    {
        "anchor": "Electromagnetic Waves Reflectance of Graphene -- Magnetic Semiconductor\n  Superlattice in Magnetic Field: Electrodynamic properties of the graphene - magnetic semiconductor - graphene\nsuperlattice placed in magnetic field have been investigated theoretically in\nFaraday geometry with taking into account dissipation processes. Frequency and\nfield dependences of the reflectance, transmittance and absorbtance of\nelectromagnetic waves by such superlattice have been calculated for different\nnumbers of periods of the structure and different sizes of the periods with\nusing a transfer matrix method. The possibility of efficient control of\nelectrodynamic properties of graphene - magnetic semiconductor - graphene\nsuperlattice has been shown.",
        "positive": "Controlled Quantum Operations of a Semiconductor Three-Qubit System: The Coulomb interactions between electrons play important roles in coupling\nmultiple qubits in various quantum systems. Here we demonstrate controlled\nquantum operations of three electron charge qubits based on three capacitively\ncoupled semiconductor double quantum dots. The strong interactions between one\ndouble dot and other two double dots enable us to control the coherent\nrotations of one target qubit by the states of two control qubits."
    },
    {
        "anchor": "Dirac Fermion in Strongly-Bound Graphene Systems: It is highly desirable to integrate graphene into existing semiconductor\ntechnology, where the combined system is thermodynamically stable yet maintain\na Dirac cone at the Fermi level. Firstprinciples calculations reveal that a\ncertain transition metal (TM) intercalated graphene/SiC(0001), such as the\nstrongly-bound graphene/intercalated-Mn/SiC, could be such a system. Different\nfrom free-standing graphene, the hybridization between graphene and Mn/SiC\nleads to the formation of a dispersive Dirac cone of primarily TM d characters.\nThe corresponding Dirac spectrum is still isotropic, and the transport behavior\nis nearly identical to that of free-standing graphene for a bias as large as\n0.6 V, except that the Fermi velocity is half that of graphene. A simple model\nHamiltonian is developed to qualitatively account for the physics of the\ntransfer of the Dirac cone from a dispersive system (e.g., graphene) to an\noriginally non-dispersive system (e.g., TM).",
        "positive": "Analysis of First Order Reversal Curves in the Thermal Hysteresis of\n  Spin-crossover Nanoparticles within the Mechanoelastic Model: The recently obtained spin-crossover nanoparticles are possible candidates\nfor applications in the recording media industry as materials for data storage,\nor as pressure and temperature sensors. For these applications the\nintermolecular interactions and interactions between spin-crossover\nnanoparticles are extremely important, as they may be essential factors in\ntriggering the transition between the two stable phases: the high-spin and\nlow-spin ones. In order to find correlations between the distributions in size\nand interactions and the transition temperatures distribution, we apply the\nFORC (First Order Reversal Curves) method, using simulations based on a\nmechanoelastic model applied to 2D triangular lattices composed of molecules\nlinked by springs and embedded in a surfactant. We consider two Gaussian\ndistributions: one of the size of the nanoparticles and one of the elastic\ninteractions between edge spin-crossover molecules and the surfactant\nmolecules. In order to disentangle the kinetic and non-kinetic parts of the\nFORC distributions, we compare the results obtained for different temperature\nsweeping rates. We also show that the presence of few larger particles in a\ndistribution centered around much smaller particles dramatically increases the\nhysteresis width."
    },
    {
        "anchor": "Strong enhancement of drag and dissipation at the weak- to strong-\n  coupling phase transition in a bi-layer system at a total Landau level\n  filling nu=1: We consider a bi-layer electronic system at a total Landau level filling\nfactor nu =1, and focus on the transition from the regime of weak inter-layer\ncoupling to that of the strongly coupled (1,1,1) phase (or ''quantum Hall\nferromagnet''). Making the assumption that in the transition region the system\nis made of puddles of the (1,1,1) phase embedded in a bulk of the weakly\ncoupled state, we show that the transition is accompanied by a strong increase\nin longitudinal Coulomb drag, that reaches a maximum of approximately\n$h/2e^{2}$. In that regime the longitudinal drag is increased with decreasing\ntemperature.",
        "positive": "Half integer features in the quantum Hall Effect: experiment and theory: The quantum Hall effect is one of the most important developments in\ncondensed matter physics of the 20th century. The standard explanations of the\nfamous integer quantized Hall plateaus in the transverse resistivity are\nqualitative, and involve assumptions about disorder, localized states, extended\nstates, edge states, Fermi levels pinned by Landau levels, etc. These standard\nnarratives give plausible reasons for the existence of the plateaus, but\nprovide little in the way of even a qualitative understanding of the shape and\nwidth of the Hall plateaus, much less a first principles calculation. The\ninjection model presented in this paper changes that situation. Rather than\nfocusing on the middle of the Hall device, we follow the electrons to their\nsource: one corner of the Hall bar and its steep electric field gradients. We\nfind the entire resistivity curve including the Hall plateaus is calculable as\na function of magnetic field, temperature, and current. The new higher current\nexperiments reported here show remarkable half integer features for the first\ntime; these are faithfully reproduced by the injection theory. The Hall\nplateaus and half integer inflections are shown to result from the local\ndensity of states appropriate to the magnetic field and the strong electric\nfield gradient at the injection corner."
    },
    {
        "anchor": "Quantum nanomagnets and nuclear spins: an overview: This mini-review presents a simple and accessible summary on the fascinating\nphysics of quantum nanomagnets coupled to a nuclear spin bath. These chemically\nsynthesized systems are an ideal test ground for the theories of decoherence in\nmesoscopic quantum degrees of freedom, when the coupling to the environment is\nlocal and not small. We shall focus here on the most striking quantum\nphenomenon that occurs in such nanomagnets, namely the tunneling of their giant\nspin through a high anisotropy barrier. It will be shown that perturbative\ntreatments must be discarded, and replaced by a more sophisticated formalism\nwhere the dynamics of the nanomagnet and the nuclei that couple to it are\ntreated together from the beginning. After a critical review of the theoretical\npredictions and their experimental verification, we continue with a set of\nexperimental results that challenge our present understanding, and outline the\nimportance of filling also this last gap in the theory.",
        "positive": "Maximum reflectance and transmittance of films coated with gapped\n  graphene in the context of Dirac model: The analytic expressions for the maximum and minimum reflectance of optical\nfilms coated with gapped graphene are derived in the application region of the\nDirac model with account of multiple reflections. The respective film\nthicknesses are also found. In so doing the film material is described by the\nfrequency-dependent index of refraction and graphene by the polarization tensor\ndefined along the real frequency axis. The developed formalism is illustrated\nby an example of the graphene-coated film made of amorphous silica. Numerical\ncomputations of the maximum and minimum reflectances and respective film\nthicknesses are performed at room temperature in two frequency regions\nbelonging to the near-infrared and far-infrared domains. It is shown that in\nthe far-infrared domain the graphene coating makes a profound effect on the\nvalues of maximum reflectance and respective film thickness leading to a\nrelative increase of their values by up to 65% and 50%, respectively. The\nmaximum transmittance of a graphene-coated film of appropriately chosen\nthickness is shown to exceed 90%. Possible applications of the obtained results\nare discussed."
    },
    {
        "anchor": "Carbon nanotubes in almost homogeneous transverse magnetic field:\n  exactly solvable model: A class of exactly solvable models describing carbon nanotubes in the\npresence of an external inhomogeneous magnetic field is considered. The\nframework of the continuum approximation is employed, where the motion of the\ncharge carriers is governed by the Dirac- Weyl equation. The explicit solution\nof a particular example is provided. It is shown that these models possess\nnontrivial integrals of motion that establish N = 2 nonlinear supersymmetry in\ncase of metallic and maximally semiconducting nanotubes. Remarkable stability\nof energy levels with respect to small fluctuations of longitudinal momentum is\ndemonstrated",
        "positive": "Strong coupling between mechanical modes in a nanotube resonator: We report on the nonlinear coupling between the mechanical modes of a\nnanotube resonator. The coupling is revealed in a pump-probe experiment where a\nmode driven by a pump force is shown to modify the motion of a second mode\nmeasured with a probe force. In a second series of experiments, we actuate the\nresonator with only one oscillating force. Mechanical resonances feature exotic\nlineshapes with reproducible dips, peaks, and jumps when the measured mode is\ncommensurate with another mode with a frequency ratio of either 2 or 3.\nConventional lineshapes are recovered by detuning the frequency ratio using the\nvoltage on a nearby gate electrode. The exotic lineshapes are attributed to\nstrong coupling between the mechanical modes. The possibility to control the\nstrength of the coupling with the gate voltage holds promise for various\nexperiments, such as quantum manipulation, mechanical signal processing, and\nthe study of the quantum-toclassical transition."
    },
    {
        "anchor": "Gate-tuned quantum oscillations of topological surface states in\n  beta-Ag2Te: We report the strong experimental evidence of the existence of topological\nsurface states with large electric field tunability and mobility in beta-Ag2Te.\nPronounced 2D SdH oscillations have been observed in beta-Ag2Te nanoplates. A\nBerry phase is determined to be near pi using the Landau level fan diagram for\na relatively wide nanoplate while the largest electric field ambipolar effect\nin topological insulator so far (~ 2500%) in a narrow nanoplate. The pi Berry\nphase and the evolution of quantum oscillations with gate voltage (Vg) in the\nnanoplates strongly indicate the presence of topological surface states in\nbeta-Ag2Te. Moreover, the mobility of the narrow Ag2Te nanoplate is ~ 3x10^4\ncm^2s^-1V^-1 when the Fermi level is near the Dirac point. The realization of\ntopological surface states with large electrical tunability and high mobility\nindicates that beta-Ag2Te is a promising topological insulator for fundamental\nstudies.",
        "positive": "Dynamic Localization in Quantum Wires: In the paper the dynamic localization of charged particle (electron) in a\nquantum wire under the external non-uniform time-dependent electric field is\nconsidered. The electrons are trapped in a deep 'dynamic' quantum wells which\nare the result of specific features of the potential imposed on 2D electron\ngas: the scale of spatial nonuniformity is much smaller then the electron mean\nfree path (L_1 << \\bar{l}) and the frequency is much greater then \\tau^{-1},\nwhere \\tau is the electron free flight time. As a result, the effect of this\nfield on the charged particle is in a sense equivalent to the effect of a\ntime-independent effective potential, that is a sequence of deep 'dynamic'\nquantum wells were the elelctrons are confined. The possible consequeces of\nthis effect are also discussed and similarity with the classical Paul traps are\nemphasized."
    },
    {
        "anchor": "Charge Qubit Purification by an Electronic Feedback Loop: We propose the manipulation of an isolated qubit by a simple instantaneous\nclosed-loop feedback scheme in which a time-dependent electronic detector\ncurrent is directly back-coupled into qubit parameters. As specific detector\nmodel we employ a capacitively coupled single-electron transistor. We\ndemonstrate the stabilization of pure delocalized qubit states above a critical\ndetector-qubit coupling. This electronic purification is independent of the\ninitial qubit state and is accomplished after few electron jumps through the\ndetector. Our simple scheme can be used for the efficient and robust\ninitialization of solid-state qubits in quantum computational algorithms at\narbitrary temperatures.",
        "positive": "Lotka-Volterra population dynamics in coherent and tunable oscillators\n  of trapped polariton condensates: We demonstrate a regime in which matter-wave condensates of\nexciton-polaritons trapped in an elliptically shaped two-dimensional potential\nappear as a coherent mixture of ground and first-excited state of the quantum\nharmonic oscillator. This system resembles an optically controllable two-level\nsystem and produces near terahertz harmonic oscillations of the condensate's\ncenter of mass along the major axis of the elliptical trapping potential. The\npopulation ratio between the two trap levels is tunable through the excitation\nlaser power and is shown to follow Lotka-Volterra dynamics. We demonstrate\ncoherence formation between two spatially displaced trapped condensate\noscillators - the polaritonic analogue of Huygen's clock synchronization for\ncoupled condensate oscillators."
    },
    {
        "anchor": "Correlated Coulomb drag in capacitively coupled quantum-dot structures: We study theoretically Coulomb drag in capacitively coupled quantum dots\n(CQDs) -- a biasdriven dot coupled to an unbiased dot where transport is due to\nCoulomb mediated energy transfer drag. To this end, we introduce a\nmaster-equation approach which accounts for higher-order tunneling\n(cotunneling) processes as well as energy-dependent lead couplings, and\nidentify a mesoscopic Coulomb drag mechanism driven by nonlocal multi-electron\ncotunneling processes. Our theory establishes the conditions for a nonzero drag\nas well as the direction of the drag current in terms of microscopic system\nparameters. Interestingly, the direction of the drag current is not determined\nby the drive current, but by an interplay between the energy-dependent lead\ncouplings. Studying the drag mechanism in a graphene-based CQD heterostructure,\nwe show that the predictions of our theory are consistent with recent\nexperiments on Coulomb drag in CQD systems.",
        "positive": "Interplay of the Rashba and Dresselhaus spin-orbit coupling in the\n  optical spin susceptibility of 2D electron systems: We present calculations of the frequency-dependent spin susceptibility tensor\nof a two-dimensional electron gas with competing Rashba and Dresselhaus\nspin-orbit interaction. It is shown that the interplay between both types of\nspin-orbit coupling gives rise to an anisotropic spectral behavior of the spin\ndensity response function which is significantly different from that of\nvanishing Rashba or Dresselhaus case. Strong resonances are developed in the\nspin susceptibility as a consequence of the angular anisotropy of the energy\nspin-splitting. This characteristic optical modulable response may be useful to\nexperimentally probe spin accumulation and spin density currents in such\nsystems."
    },
    {
        "anchor": "Magneto-optics of quasi-relativistic electrons in tilted Dirac cones in\n  graphene and $\u03b1$-(BEDT-TTF)$_2$I$_3$: Massless Dirac fermions occur as low-energy modes in several\nquasi-two-dimensional condensed matter systems such as graphene, the surface of\nbulk topological insulators, and in layered organic semiconductors. When the\nrotational symmetry in such systems is reduced either by an in-plane electric\nfield or an intrinsic tilt of the Dirac cones, the allowed dipolar optical\ntransitions evolve from a few selected transitions into a wide fan of interband\ntransitions. We show that the Lorentz covariance of the low-energy carriers\nallows for a concise analysis of the emerging magneto-optical properties. We\npredict that infrared absorption spectra yield quantitative information on the\ntilted Dirac cone structure in organic compounds such as\n$\\alpha$-(BEDT-TTF)$_2$I$_3$.",
        "positive": "Low-high voltage duality in tunneling spectroscopy of the\n  Sachdev-Ye-Kitaev model: The Sachdev-Ye-Kitaev (SYK) model describes a strongly correlated metal with\nall-to-all random interactions (average strength $J$) between $N$ fermions\n(complex Dirac fermions or real Majorana fermions). In the large-$N$ limit a\nconformal symmetry emerges that renders the model exactly soluble. Here we\nstudy how the non-Fermi liquid behavior of the closed system in equilibrium\nmanifests itself in an open system out of equilibrium. We calculate the\ncurrent-voltage characteristic of a quantum dot, described by the\ncomplex-valued SYK model, coupled to a voltage source via a single-channel\nmetallic lead (coupling strength $\\Gamma$). A one-parameter scaling law appears\nin the large-$N$ conformal regime, where the differential conductance $G=dI/dV$\ndepends on the applied voltage only through the dimensionless combination\n$\\xi=eVJ/\\Gamma^2$. Low and high voltages are related by the duality\n$G(\\xi)=G(\\pi/\\xi)$. This provides for an unambiguous signature of the\nconformal symmetry in tunneling spectroscopy."
    },
    {
        "anchor": "The One-dimensional Chiral Anomaly and its Disorder Response: The condensed-matter realization of chiral anomaly has attracted tremendous\ninterest in exploring unexpected phenomena of quantum field theory. Here, we\nshow that one-dimensional (1D) chiral anomaly (i.e., 1D nonconservational\nchiral current under a background electromagnetic field) can be realized in a\ngeneralized Su-Schrieffer-Heeger model where a single gapless Dirac cone\noccurs. Based on the topological Thouless pump and anomalous dynamics of chiral\ndisplacement, we elucidate that such a system possesses the half-integer\nquantization of winding number. Moreover, we investigate the evolution of 1D\nchiral anomaly with respect to two typical types of disorder, i.e., on-site\ndisorder and bond disorder. The results show that the on-site disorder tends to\nsmear the gapless Dirac cone. However, we propose a strategy to stabilize the\nhalf-integer quantization, facilitating its experimental detection.\nFurthermore, we demonstrate that the bond disorder causes a unique crossover\nwith disorder-enhanced topological charge pumping, driving the system into a\ntopological Anderson insulator phase.",
        "positive": "The Casimir effect for stack of graphenes: We consider a stack of parallel sheets composed of conducting planes with\ntensorial conductivities. Using the scattering matrix approach, we derive\nexplicit formulas for the Casimir energy of two, three, and four planes, as\nwell as a recurrence relation for arbitrary planes. Specifically, for a stack\nof graphene, we solve the recurrence relations and obtain formulas for the\nCasimir energy and force acting on the planes within the stack. Moreover, we\ncalculate the binding energy in the graphene stack with graphite interplane\nseparation, which amounts to $E_{ib} = 9.9$ meV/atom. Notably, the Casimir\nforce on graphene sheets decreases rapidly for planes beyond the first one. In\nparticular, for the second graphene layer in the stack, the force is $35$ times\nsmaller than that experienced by the first layer."
    },
    {
        "anchor": "Hysteretic behavior in weakly coupled double-dot transport in the spin\n  blockade regime: Double quantum dot systems in the spin blockade regime exhibit leakage\ncurrents that have been attributed to the Hyperfine interaction. We model\nweakly coupled double-dot transport using a rate equation approach which\naccounts for Hyperfine flip-flop transitions. The rate equations allow us to\nobtain self-consistently the time evolution for electronic charge occupations\nand for the nuclei polarizations in each dot. We analyze the current in the\nspin blockade region as a function of magnetic field and observe hysteretic\nbehavior for fields corresponding to the crossing between triplet and singlet\nstates.",
        "positive": "Dephasing and Renormalization in Quantum Two-Level Systems: Motivated by fundamental questions about the loss of phase coherence at low\ntemperature we consider relaxation, dephasing and renormalization effects in\nquantum two-level systems which are coupled to a dissipative environment. We\nobserve that experimental conditions, e.g., details of the initial state\npreparation, determine to which extent the environment leads to dephasing or to\nrenormalization effects. We analyze an exactly solvable limit where the\nrelation between both can be demonstrated explicitly. We also study the effects\nof dephasing and renormalization on response functions."
    },
    {
        "anchor": "Flatband generator in two dimensions: Dispersionless bands -- \\emph{flatbands} -- provide an excellent testbed for\nnovel physical phases due to the fine-tuned character of flatband tight-binding\nHamiltonians. The accompanying macroscopic degeneracy makes any perturbation\nrelevant, no matter how small. For short-range hoppings flatbands support\ncompact localized states, which allowed to develop systematic flatband\ngenerators in $d=1$ dimension in Phys. Rev. B {\\bf 95} 115135 (2017) and Phys.\nRev. B {\\bf 99} 125129 (2019). Here we extend this generator approach to $d=2$\ndimensions. The \\emph{shape} of a compact localized state turns into an\nimportant additional flatband classifier. This allows us to obtain analytical\nsolutions for classes of $d=2$ flatband networks and to re-classify and\nre-obtain known ones, such as the checkerboard, kagome, Lieb and Tasaki\nlattices. Our generator can be straightforwardly generalized to three lattice\ndimensions as well.",
        "positive": "Hybrid InAs nanowire-vanadium proximity SQUID: We report the fabrication and characterization of superconducting quantum\ninterference devices (SQUIDs) based on InAs nanowires and vanadium\nsuperconducting electrodes. These mesoscopic devices are found to be extremely\nrobust against thermal cycling and to operate up to temperatures of $\\sim2.5$~K\nwith reduced power dissipation. We show that our geometry allows to obtain\nnearly-symmetric devices with very large magnetic-field modulation of the\ncritical current. All these properties make these devices attractive for\non-chip quantum-circuit implementation."
    },
    {
        "anchor": "Imaging tunable quantum Hall broken-symmetry orders in graphene: When electrons populate a flat band their kinetic energy becomes negligible,\nforcing them to organize in exotic many-body states to minimize their Coulomb\nenergy. The zeroth Landau level of graphene under magnetic field is a\nparticularly interesting strongly interacting flat band because inter-electron\ninteractions are predicted to induce a rich variety of broken-symmetry states\nwith distinct topological and lattice-scale orders. Evidence for these stems\nmostly from indirect transport experiments that suggest that broken-symmetry\nstates are tunable by boosting the Zeeman energy or by dielectric screening of\nthe Coulomb interaction. However, confirming the existence of these ground\nstates requires a direct visualization of their lattice-scale orders. Here, we\nimage three distinct broken-symmetry phases in graphene using scanning\ntunneling spectroscopy. We explore the phase diagram by tuning the screening of\nthe Coulomb interaction by a low or high dielectric constant environment, and\nwith a magnetic field. In the unscreened case, we unveil a Kekul\\'e bond order,\nconsistent with observations of an insulating state undergoing a magnetic-field\ndriven Kosterlitz-Thouless transition. Under dielectric screening, a\nsublattice-unpolarized ground state emerges at low magnetic fields, and\ntransits to a charge-density-wave order with partial sublattice polarization at\nhigher magnetic fields. The Kekul\\'e and charge-density-wave orders furthermore\ncoexist with additional, secondary lattice-scale orders that enrich the phase\ndiagram beyond current theory predictions. This screening-induced tunability of\nbroken-symmetry orders may prove valuable to uncover correlated phases of\nmatter in other quantum materials.",
        "positive": "Weak and Strong coupling regimes in plasmonic-QED: We present a quantum theory for the interaction of a two level emitter with\nsurface plasmon polaritons confined in single-mode waveguide resonators. Based\non the Green's function approach, we develop the conditions for the weak and\nstrong coupling regimes by taking into account the sources of dissipation and\ndecoherence: radiative and non-radiative decays, internal loss processes in the\nemitter, as well as propagation and leakage losses of the plasmons in the\nresonator. The theory is supported by numerical calculations for several\nquantum emitters, GaAs and CdSe quantum dots and NV centers together with\ndifferent types of resonators constructed of hybrid, cylindrical or wedge\nwaveguides. We further study the role of temperature and resonator length.\nAssuming realistic leakage rates, we find the existence of an optimal length at\nwhich strong coupling is possible. Our calculations show that the strong\ncoupling regime in plasmonic resonators is accessible within current technology\nwhen working at very low temperatures (<4K). In the weak coupling regime our\ntheory accounts for recent experimental results. By further optimization we\nfind highly enhanced spontaneous emission with Purcell factors over 1000 at\nroom temperature for NV-centers. We finally discuss more applications for\nquantum nonlinear optics and plasmon-plasmon interactions."
    },
    {
        "anchor": "Strong Tunneling in the Single-Electron Box: We study strong tunneling (i.e. transmission $h/e^2R_T \\gg 1$) in the\nsingle-electron box with many transverse modes at zero temperature. We develop\na new renormalization group method which includes all charge states and\nrequires no initial or final energy cutoff. We determine the ground-state\nenergy, the average charge and the renormalized charging energy. The covered\nrange for the coupling constant and the gate voltage is much increased in\ncomparison to recent perturbative approaches, poor man scaling methods and\nQuantum Monte Carlo simulations. We reach the regime where Coulomb blockade\nbecome practically unobservable.",
        "positive": "Thermal theory of aluminum particle ignition in continuum,\n  free-molecular, and transition heat transfer regimes: Most studies on nano- and micro- sized aluminum particle ignition have been\nfocused on the processes occuring inside particles. In the current paper,\nthermal ignition of an aluminum particle in the air is simulated with different\nheat transfer models: continuum, free-molecular and Fuchs model. A single\nparabolic oxidation law is assumed in the particle size range from nano- to\nmillimeter diameters. A particle is considered ignited when it reaches the\noxide melting point. The criterion defining the limits of validity for each\nmodel is the ratio of continuum and free-molecular heat transfer rates. The\ndependence of ignition temperature $T_i$ on particle size is in a qualitative\nagreement with the experimental trends: $T_i$ can have values in the range\n700--1500 K for nanoparticles due to the dominating contribution of a\nfree-molecular heat transfer, and sharp growth of $T_i$ with the particle size\nin the range of 1-100 $\\mu$m diameter is due to the transitional character of\nheat transfer. For small values of accommodation coefficient, ignition may\noccur in the critical ignition mode with the thermal runaway. The results\nsuggest the importance of heat transfer and, in particular, energy\naccommodation in ignition of nano- and micro- sized particles."
    },
    {
        "anchor": "Minimal conductivity, topological Berry winding and duality in\n  three-band semimetals: The physics of massless relativistic quantum particles has recently arisen in\nthe electronic properties of solids following the discovery of graphene. Around\nthe accidental crossing of two energy bands, the electronic excitations are\ndescribed by a Weyl equation initially derived for ultra-relativistic\nparticles. Similar three and four band semimetals have recently been discovered\nin two and three dimensions. Among the remarkable features of graphene are the\ncharacterization of the band crossings by a topological Berry winding, leading\nto an anomalous quantum Hall effect, and a finite minimal conductivity at the\nband crossing while the electronic density vanishes. Here we show that these\ntwo properties are intimately related: this result paves the way to a direct\nmeasure of the topological nature of a semi-metal. By considering three band\nsemimetals with a flat band in two dimensions, we find that only few of them\nsupport a topological Berry phase. The same semimetals are the only ones\ndisplaying a non vanishing minimal conductivity at the band crossing. The\nexistence of both a minimal conductivity and a topological robustness\noriginates from properties of the underlying lattice, which are encoded not by\na symmetry of their Bloch Hamiltonian, but by a duality.",
        "positive": "Evidence of orbital ferromagnetism in twisted bilayer graphene aligned\n  to hexagonal boron nitride: We have previously reported ferromagnetism evinced by a large hysteretic\nanomalous Hall effect in twisted bilayer graphene (tBLG). Subsequent\nmeasurements of a quantized Hall resistance and small longitudinal resistance\nconfirmed that this magnetic state is a Chern insulator. Here we report that,\nwhen tilting the sample in an external magnetic field, the ferromagnetism is\nhighly anisotropic. Because spin-orbit coupling is negligible in graphene such\nanisotropy is unlikely to come from spin, but rather favors theories in which\nthe ferromagnetism is orbital. We know of no other case in which ferromagnetism\nhas a purely orbital origin. For an applied in-plane field larger than $5\\\n\\mathrm{T}$, the out-of-plane magnetization is destroyed, suggesting a\ntransition to a new phase."
    },
    {
        "anchor": "Coherent electron transport in a Si quantum dot dimer: We show that the coherence of charge transfer through a weakly coupled\ndouble-dot dimer can be determined by analyzing the statistics of the\nconductance pattern, and does not require large phase coherence length in the\nhost material. We present an experimental study of the charge transport through\na small Si nanostructure, which contains two quantum dots. The transport\nthrough the dimer is shown to be coherent. At the same time, one of the dots is\nstrongly coupled to the leads, and the overall transport is dominated by\ninelastic co-tunneling processes.",
        "positive": "Multitude of exceptional points in van der Waals magnets: Several works have recently addressed the emergence of exceptional points\n(EPs), i.e., spectral singularities of non-Hermitian Hamiltonians, in the\nlong-wavelength dynamics of coupled magnetic systems. Here, by focusing on the\ndriven magnetization dynamics of a van der Waals ferromagnetic bilayer, we show\nthat exceptional points can appear over extended portions of the first\nBrillouin zone as well. Furthermore, we demonstrate that the effective\nnon-Hermitian magnon Hamiltonian, whose eigenvalues are purely real or come in\ncomplex-conjugate pairs, respects an unusual wavevector-dependent\npseudo-Hermiticity. Finally, for both armchair and zigzag nanoribbon\ngeometries, we discuss both the complex and purely real spectra of the\ntopological edge states and their experimental implications."
    },
    {
        "anchor": "Quantitative study of the response of a single NV defect in diamond to\n  magnetic noise: The nitrogen-vacancy (NV) defect in diamond is an efficient quantum sensor of\nrandomly fluctuating signals via relaxometry measurements. In particular, the\nlongitudinal spin relaxation of the NV defect accelerates in the presence of\nmagnetic noise with a spectral component at its electron spin resonance\nfrequency. We look into this effect quantitatively by applying a calibrated and\ntunable magnetic noise on a single NV defect. We show that an increase of the\nlongitudinal spin relaxation rate translates into a reduction of the\nphotoluminescence (PL) signal emitted under continuous optical illumination,\nwhich can be explained using a simplified three-level model of the NV defect.\nThis PL quenching mechanism offers a simple, all-optical method to detect\nmagnetic noise sources at the nanoscale.",
        "positive": "Two linear regimes in optical conductivity of a Type-I Weyl semimetal:\n  the case of elemental tellurium: Employing high-pressure infrared spectroscopy we unveil the Weyl semimetal\nphase of elemental Te and its topological properties. The linear frequency\ndependence of the optical conductivity provides clear evidence for\nmetallization of trigonal tellurium (Te-I) and the linear band dispersion above\n3.0 GPa. This semimetallic Weyl phase can be tuned by increasing pressure\nfurther: a kink separates two linear regimes in the optical conductivity (at\n3.7 GPa), a signature proposed for Type-II Weyl semimetals with tilted cones;\nthis however reveals a different origin in trigonal tellurium. Our\ndensity-functional calculations do not reveal any significant tilting and\nsuggest that Te-I remains in the Type-I Weyl phase, but with two valence\nbandsin the vicinity of the Fermi level. Their interplay giving rise to the\npeculiar optical conductivity behavior with more than one linear regime.\nPressure above 4.3 GPa stabilizes the more complex Te-II and Te-III polymorphs,\nwhich are robust metals."
    },
    {
        "anchor": "Andreev tunneling through a double quantum-dot system coupled to a\n  ferromagnet and a superconductor: effects of mean field electronic\n  correlations: We study the transport properties of a hybrid nanostructure composed of a\nferromagnet, two quantum dots, and a superconductor connected in series. By\nusing the non-equilibrium Green's function approach, we have calculated the\nelectric current, the differential conductance and the transmittance for\nenergies within the superconductor gap. In this regime, the mechanism of charge\ntransmission is the Andreev reflection, which allows for a control of the\ncurrent through the ferromagnet polarization. We have also included interdot\nand intradot interactions, and have analyzed their influence through a mean\nfield approximation. In the presence of interactions, Coulomb blockade tend to\nlocalized the electrons at the double-dot system, leading to an asymmetric\npattern for the density of states at the dots, and thus reducing the\ntransmission probability through the device. In particular, for non-zero\npolarization, the intradot interaction splits the spin degeneracy, reducing the\nmaximum value of the current due to different spin-up and spin-down densities\nof states. Negative differential conductance (NDC) appears for some regions of\nthe voltage bias, as a result of the interplay of the Andreev scattering with\nelectronic correlations. By applying a gate voltage at the dots, one can tune\nthe effect, changing the voltage region where this novel phenomenon appears.\nThis mechanism to control the current may be of importance in technological\napplications.",
        "positive": "Effective Field Theory of Relativistic Quantum Hall Systems: Motivated by the observation of the fractional quantum Hall effect in\ngraphene, we consider the effective field theory of relativistic quantum Hall\nstates. We find that, beside the Chern-Simons term, the effective action also\ncontains a term of topological nature, which couples the electromagnetic field\nwith a topologically conserved current of $2+1$ dimensional relativistic fluid.\nIn contrast to the Chern-Simons term, the new term involves the spacetime\nmetric in a nontrivial way. We extract the predictions of the effective theory\nfor linear electromagnetic and gravitational responses. For fractional quantum\nHall states at the zeroth Landau level, additional holomorphic constraints\nallow one to express the results in terms of two dimensionless constants of\ntopological nature."
    },
    {
        "anchor": "Angle-Resolved Spectroscopy of Electron-Electron Scattering in a 2D\n  System: Electron-beam propagation experiments have been used to determine the energy\nand angle dependence of electron-electron (ee) scattering a two-dimensional\nelectron gas (2DEG) in a very direct manner by a new spectroscopy method. The\nexperimental results are in good agreement with recent theories and provide\ndirect evidence for the differences between ee-scattering in a 2DEG as compared\nwith 3D systems. Most conspicuous is the increased importance of small-angle\nscattering in a 2D system, resulting in a reduced (but energy-dependent)\nbroadening of the electron beam.",
        "positive": "Dynamics of Nonground-State Bose-Einstein Condensates: Dilute Bose gases, cooled down to low temperatures below the Bose-Einstein\ncondensation temperature, form coherent ensembles described by the\nGross-Pitaevskii equation. Stationary solutions to the latter are topological\ncoherent modes. The ground state, corresponding to the lowest energy level,\ndefines the standard Bose-Einstein condensate, while the states with higher\nenergy levels represent nonground-state condensates. The higher modes can be\ngenerated by alternating fields, whose frequencies are in resonance with the\nassociated transition frequencies. The condensate with topological coherent\nmodes exhibits a variety of nontrivial effects. Here it is demonstrated that\nthe dynamical transition between the mode-locked and mode-unlocked regimes is\naccompanied by noticeable changes in the evolutional entanglement production."
    },
    {
        "anchor": "Suppression of Decoherence tied to Electron-Phonon Coupling in\n  Telecom-Compatible Quantum Dots: Low-threshold Reappearance Regime for\n  Quantum State Inversion: We demonstrate full suppression of dephasing tied to deformation potential\ncoupling of confined electrons to longitunidal acoustic (LA) phonons in optical\ncontrol experiments on large semiconductor quantum dots (QDs) with emission\ncompatible with the low-dispersion telecommunications band at 1.3~$\\mu$m. By\nexploiting the sensitivity of the electron-phonon spectral density to the size\nand shape of the QD, we demonstrate a four-fold reduction in the threshold\npulse area required to enter the decoupled regime for exciton inversion using\nadiabatic rapid passage (ARP). Our calculations of the quantum state dynamics\nprovide good agreement with our experimental results and indicate that the\nsymmetry of the QD wave function provides an additional means to engineer the\nelectron-phonon interaction. Our findings will support the development of\nsolid-state quantum emitters in future distributed quantum networks using\nsemiconductor QDs.",
        "positive": "Quantum supercurrent transistors in carbon nanotubes: Electronic transport through nanostructures is greatly affected by the\npresence of superconducting leads. If the interface between the nanostructure\nand the superconductors is sufficiently transparent, a dissipationless current\n(supercurrent) can flow through the device due to the Josephson effect. A\nJosephson coupling, as measured via the zero-resistance supercurrent, has been\nobtained via tunnel barriers, superconducting constrictions, normal metals, and\nsemiconductors. The coupling mechanisms vary from tunneling to Andreev\nreflection. The latter process has always occurred via a normal-type system\nwith a continuous density of states. Here we investigate a supercurrent flowing\nvia a discrete density of states, i.e., the quantized single particle energy\nstates of a quantum dot, or artificial atom, placed in between superconducting\nelectrodes. For this purpose, we exploit the quantum properties of finite-sized\ncarbon nanotubes (CNTs). By means of a gate electrode, successive discrete\nenergy states are tuned ON and OFF resonance with the Fermi energy in the\nsuperconducting leads, resulting in a periodic modulation of the critical\ncurrent and a non-trivial correlation between the conductance in the normal\nstate and the supercurrent. We find, in good agreement with existing theory,\nthat the product of the critical current and the normal state resistance\nbecomes an oscillating function, in contrast to being constant as in previously\nexplored regimes."
    },
    {
        "anchor": "Coexistence of electron and hole transport in graphene: When sweeping the carrier concentration in monolayer graphene through the\ncharge neutrality point, the experimentally measured Hall resistivity shows a\nsmooth zero crossing. Using a two- component model of coexisting electrons and\nholes around the charge neutrality point, we unambiguously show that both types\nof carriers are simultaneously present. For high magnetic fields up to 30 T the\nelectron and hole concentrations at the charge neutrality point increase with\nthe degeneracy of the zero-energy Landau level which implies a quantum Hall\nmetal state at \\nu=0 made up by both electrons and holes.",
        "positive": "Honing in on a topological zero-bias conductance peak: A popular signature of Majorana bound states in topological superconductors\nis the zero-energy conductance peak with a height of $2e^2/h$. However, a\nsimilar zero energy conductance peak with almost the same height can also arise\ndue to non-topological reasons. Here we show that these trivial and topological\nzero energy conductance peaks can be distinguished via the zero energy local\ndensity of states and local magnetization density of states. We find that the\nzero-energy local density of states exhibits oscillations with a finite period\nfor a trivial zero-bias conductance peak. In contrast, these oscillations\ndisappear for the topological zero-bias conductance peak. On the other hand,\nzero energy local magnetization density of states shows a periodic oscillation\nfor trivial zero-bias conductance peak, while for topological ZBCP, they\nvanish. Our results suggest that zero-energy local density of states and local\nmagnetization density of states can be used as an experimental probe to\ndistinguish trivial zero energy conductance peak from topological zero energy\nconductance peak."
    },
    {
        "anchor": "Injection and detection of spin in a semiconductor by tunneling via\n  interface states: Injection and detection of spin accumulation in a semiconductor having\nlocalized states at the interface is evaluated. Spin transport from a\nferromagnetic contact by sequential, two-step tunneling via interface states is\ntreated not in itself, but in parallel with direct tunneling. The spin\naccumulation induced in the semiconductor channel is not suppressed, as\npreviously argued, but genuinely enhanced by the additional spin current via\ninterface states. Spin detection with a ferromagnetic contact yields a weighted\naverage of the spin accumulation in the channel and in the localized states. In\nthe regime where the spin accumulation in the localized states is much larger\nthan that in the channel, the detected spin signal is insensitive to the spin\naccumulation in the localized states and the ferromagnet probes the spin\naccumulation in the semiconductor channel.",
        "positive": "Linear scaling calculation of a n-type GaAs quantum dot: A linear scale method for calculating electronic properties of large and\ncomplex systems is introduced within a local density approximation. The method\nis based on the Chebyshev polynomial expansion and the time-dependent method,\nwhich is tested in calculating the electronic structure of a model n-type GaAs\nquantum dot."
    },
    {
        "anchor": "Transport through two-level quantum dots weakly coupled to ferromagnetic\n  leads: Spin-dependent transport through a two-level quantum dot in the sequential\ntunneling regime is analyzed theoretically by means of a real-time diagrammatic\ntechnique. It is shown that the current, tunnel magnetoresistance, and shot\nnoise (Fano factor) strongly depend on the transport regime, providing a\ndetailed information on the electronic structure of quantum dots and their\ncoupling to external leads. When the dot is asymmetrically coupled to the\nleads, a negative differential conductance may occur in certain bias regions,\nwhich is associated with a super-Poissonian shot noise. In the case of a\nquantum dot coupled to one half-metallic and one nonmagnetic lead, one finds\ncharacteristic Pauli spin blockade effects. Transport may be also suppressed\nwhen the dot levels are coupled to the leads with different coupling strengths.\nThe influence of an external magnetic field on transport properties is also\ndiscussed.",
        "positive": "Theory of anisotropic exchange in laterally coupled quantum dots: The effects of spin-orbit coupling on the two-electron spectra in lateral\ncoupled quantum dots are investigated analytically and numerically. It is\ndemonstrated that in the absence of magnetic field the exchange interaction is\npractically unaffected by spin-orbit coupling, for any interdot coupling,\nboosting prospects for spin-based quantum computing. The anisotropic exchange\nappears at finite magnetic fields. A numerically accurate effective spin\nHamiltonian for modeling spin-orbit-induced two-electron spin dynamics in the\npresence of magnetic field is proposed."
    },
    {
        "anchor": "Anomalous quantum interference effects in graphene SNS junctions due to\n  strain-induced gauge fields: We investigate the influence of gauge fields induced by strain on the\nsupercurrent passing through the graphene-based Josephson junctions. We show in\nthe presence of a constant pseudomagnetic field ${\\bf B}_S$ originated from an\narc-shape elastic deformation, the Josephson current is monotonically enhanced.\nThis is in contrast with the oscillatory behavior of supercurrent (known as\nFraunhofer pattern) caused by real magnetic fields passing through the\njunction. The absence of oscillatory supercurrent originates from the fact that\nstrain-induced gauge fields have opposite directions at the two valleys due to\nthe time-reversal symmetry. Subsequently there is no net Aharonov-Bohm effect\ndue to ${\\bf B}_S$ in the current carried by the bound states composed of\nelectrons and holes from different valleys. On the other hand, when both\nmagnetic and pseudomagnetic fields are present, Fraunhofer-like oscillations as\nfunction of the real magnetic field flux are found. We find that the Fraunhofer\npattern and in particular its period slightly change by varying the\nstrain-induced gauge field as well as the geometric aspect ratio of the\njunction. Intriguingly, the combination of two kinds of gauge fields results in\ntwo special fingerprint in the local current density profile: (i) strong\nlocalization of the Josephson current density with more intense maximum\namplitudes; (ii) appearance of the inflated vortex cores - finite regions with\nalmost diminishing Josephson currents - which their sizes increases by\nincreasing ${\\bf B}_S$. These findings reveal unexpected interference\nsignatures of strain-induced gauge fields in graphene SNS junctions and provide\nunique tools for sensitive probing of the pseudomagnetic fields.",
        "positive": "Dynamical correlation functions and the related physical effects in\n  three-dimensional Weyl/Dirac semimetals: We present a unified derivation of the dynamical correlation functions\nincluding density-density, density-current and current-current, of\nthree-dimensional Weyl/Dirac semimetals by use of the Passarino-Veltman\nreduction scheme at zero temperature. The generalized Kramers-Kronig relations\nwith arbitrary order of subtraction are established to verify these correlation\nfunctions. Our results lead to the exact chiral magnetic conductivity and\ndirectly recover the previous ones in several limits. We also investigate the\nmagnetic susceptibilities, the orbital magnetization and briefly discuss the\nimpact of electron interactions on these physical quantities within the random\nphase approximation. Our work could provide a starting point for the\ninvestigation of the nonlocal transport and optical properties due to the\nhigher-order spatial dispersion in three-dimensional Weyl/Dirac semimetals."
    },
    {
        "anchor": "Superconducting fluctuations in small grains - the Universal Hamiltonian\n  and the reduced BCS model: Small superconducting grains are discussed in the frameworks of both the\nreduced BCS Hamiltonian and the Universal Hamiltonian. It is shown that\nfluctuations of electrons in levels far from the Fermi energy dominate\nsuperconducting properties in small and ultrasmall grains. Experimental\nconsequences related to the spin susceptibility and persistent currents of\ngrains and rings with weak electron-electron interactions are discussed.",
        "positive": "Double-quantum spin-relaxation limits to coherence of near-surface\n  nitrogen-vacancy centers: We probe the relaxation dynamics of the full three-level spin system of\nnear-surface nitrogen-vacancy (NV) centers in diamond to define a $T_{1}$\nrelaxation time that helps resolve the $T_{2} \\leq 2T_{1}$ coherence limit of\nthe NV's subset qubit superpositions. We find that double-quantum spin\nrelaxation via electric field noise dominates $T_{1}$ of near-surface NVs at\nlow applied magnetic fields. Furthermore, we differentiate $1/f^{\\alpha}$\nspectra of electric and magnetic field noise using a novel noise-spectroscopy\ntechnique, with broad applications in probing surface-induced decoherence at\nmaterial interfaces."
    },
    {
        "anchor": "Charge and Spin Transport in Magnetic Tunnel Junctions: Microscopic\n  Theory: We study the charge and spin currents passing through a magnetic tunnel\njunction (MTJ) on the basis of a tight-binding model. The currents are\nevaluated perturbatively with respect to the tunnel Hamiltonian. The charge\ncurrent has the form $A[\\bm M_1(t)\\times\\dot{\\bm M}_1(t)]\\cdot\\bm M_2+B\\dot{\\bm\nM}_1(t)\\cdot\\bm M_2$, where $\\bm M_1(t)$ and $\\bm M_2$ denote the directions of\nthe magnetization in the free layer and fixed layer, respectively. The constant\n$A$ vanishes when one or both layers are insulators, {while the constant $B$\ndisappears when both layers are insulators or the same ferromagnets.} The first\nterm in the expression for charge current represents dissipation driven by the\neffective electric field induced by the dynamic magnetization. In addition,\nfrom an investigation of the spin current, we obtain the microscopic expression\nfor the enhanced Gilbert damping constant $\\varDelta \\alpha$. We show that\n$\\varDelta\\alpha$ is proportional to the tunnel conductance and depends on the\nbias voltage.",
        "positive": "Physical rendering of synthetic spaces for topological sound transport: Synthetic dimensions can be rendered in the physical space and this has been\nachieved with photonics and cold atomic gases, however, little to no work has\nbeen succeeded in acoustics because acoustic wave-guides cannot be weakly\ncoupled in a continuous fashion. Here, we establish the theoretical principles\nand for the first time manufacture acoustic crystals composed of arrays of\nacoustic cavities strongly coupled through modulated channels to evidence\none-dimensional (1D) and two-dimensional (2D) dynamic topological pumpings. In\nparticular, the topological edge-bulkedge and corner-bulk-corner transport are\nphysically illustrated in finite-sized acoustic structures. We delineate the\ngenerated 2D and four-dimensional (4D) quantum Hall effects by calculating\nfirst and second Chern numbers and demonstrating robustness against the\ngeometrical imperfections. Synthetic dimensions could provide a powerful way\nfor acoustic topological wave steering and open up a new platform to explore\nhigher-order topological matter in dimensions four and higher."
    },
    {
        "anchor": "Nonlinear thermoelectricity in point-contacts at pinch-off: a\n  catastrophe aids cooling: We consider refrigeration and heat engine circuits based on the nonlinear\nthermoelectric response of point-contacts at pinch-off, allowing for\nelectrostatic interaction effects. We show that a refrigerator can cool to much\nlower temperatures than predicted by the thermoelectric figure-of-merit ZT\n(which is based on linear-response arguments). The lowest achievable\ntemperature has a discontinuity, called a fold catastrophe in mathematics, at a\ncritical driving current I=I_c. For I >I_c one can in principle cool to\nabsolute zero, when for I<I_c the lowest temperature is about half the ambient\ntemperature. Heat back-flow due to phonons and photons stop cooling at a\ntemperature above absolute zero, and above a certain threshold turns the\ndiscontinuity into a sharp cusp. We also give a heuristic condition for when an\narbitrary system's nonlinear response means that its ZT ceases to indicate\n(even qualitatively) the lowest temperature to which the system can\nrefrigerate.",
        "positive": "Electric field induced tuning of electronic correlation in weakly\n  confining quantum dots: We conduct a combined experimental and theoretical study of the\nquantum-confined Stark effect in GaAs/AlGaAs quantum dots obtained with the\nlocal droplet etching method. In the experiment, we probe the permanent\nelectric dipole and polarizability of neutral and positively charged excitons\nweakly confined in GaAs quantum dots by measuring their light emission under\nthe influence of a variable electric field applied along the growth direction.\nCalculations based on the configuration-interaction method show excellent\nquantitative agreement with the experiment and allow us to elucidate the role\nof Coulomb interactions among the confined particles and -- even more\nimportantly -- of electronic correlation effects on the Stark shifts. Moreover,\nwe show how the electric field alters properties such as built-in dipole,\nbinding energy, and heavy-light hole mixing of multiparticle complexes in\nweakly confining systems, underlining the deficiencies of commonly used models\nfor the quantum-confined Stark effect."
    },
    {
        "anchor": "Cascade of isospin phase transitions in Bernal bilayer graphene at zero\n  magnetic field: Emergent phenomena arising from the collective behavior of electrons is\ngenerally expected when Coulomb interactions dominate over the kinetic energy,\nas in delocalized quasiparticles in highly degenerate flat bands.\nBernal-stacked bilayer graphene intrinsically supports a pair of flat bands\npredicted to host a variety of spontaneous broken-symmetry states arising from\nvan Hove singularities and a four-fold spin-valley (isospin) degeneracy. Here,\nwe show that ultra-clean samples of bilayer graphene display a cascade of\nsymmetry-broken states with spontaneous and spin and valley ordering at zero\nmagnetic field. Using capacitive sensing in a dual-gated geometry, we tune the\ncarrier density and electric displacement field independently to explore the\nphase space of transitions and probe the character of the isospin order.\nItinerant ferromagnetic states emerge near the conduction and valence band\nedges with complete spin and valley polarization and a high degree of\ndisplacement field tunability. At larger hole densities, two-fold degenerate\nquantum oscillations manifest in an additional broken symmetry state that is\nenhanced by the application of an in-plane magnetic field. Both types of\nsymmetry-broken states display enhanced layer polarization at low temperatures,\nsuggesting a coupling to the layer pseudospin degree of freedom in the\nelectronic wavefunctions. Notably, the zero-field spontaneous symmetry breaking\nreported here emerges in the absence of a moir\\'e superlattice and is intrinsic\nto natural graphene bilayers. Thus, we demonstrate that the tunable bands of\nbilayer graphene represent a related, but distinct approach to produce flat\nband collective behavior, complementary to engineered moir\\'e structures.",
        "positive": "van der Waals coupling in atomically doped carbon nanotubes: We have investigated atom-nanotube van der Waals (vdW) coupling in atomically\ndoped carbon nanotubes (CNs). Our approach is based on the perturbation theory\nfor degenerated atomic levels, thus accounting for both weak and strong\natom-vacuum-field coupling. The vdW energy is described by an integral equation\nrepresented in terms of the local photonic density of states (DOS). By solving\nit numerically, we demonstrate the inapplicability of standard\nweak-coupling-based vdW interaction models in a close vicinity of the CN\nsurface where the local photonic DOS effectively increases, giving rise to an\natom-field coupling enhancement. An inside encapsulation of atoms into the CN\nhas been shown to be energetically more favorable than their outside adsorption\nby the CN surface. If the atom is fixed outside the CN, the modulus of the vdW\nenergy increases with the CN radius provided that the weak atom-field coupling\nregime is realized (i.e., far enough from the CN). For inside atomic position,\nthe modulus of the vdW energy decreases with the CN radius, representing a\ngeneral effect of the effective interaction area reduction with lowering the CN\ncurvature."
    },
    {
        "anchor": "Decay and Frequency Shift of Inter and Intravalley Phonons in Graphene\n  -Dirac Cone Migration-: By considering analytical expressions for the self-energies of intervalley\nand intravalley phonons in graphene, we describe the behavior of D, 2D, and\nD$'$ Raman bands with changes in doping ($\\mu$) and light excitation energy\n($E_L$). Comparing the self-energy with the observed $\\mu$ dependence of the 2D\nbandwidth, we estimate the wavevector $q$ of the constituent intervalley phonon\nat $\\hbar vq\\simeq E_L/1.6$ ($v$ is electron's Fermi velocity) and conclude\nthat the self-energy makes a major contribution (60%) to the dispersive\nbehavior of the D and 2D bands. The estimation of $q$ is based on an image of\nshifted Dirac cones in which the resonance decay of a phonon satisfying $q >\n\\omega/v$ ($\\omega$ is the phonon frequency) into an electron-hole pair is\nsuppressed when $\\mu < (vq-\\omega)/2$. We highlight the fact that the decay of\nan intervalley (and intravalley longitudinal optical) phonon with $q=\\omega/v$\nis strongly suppressed by electron-phonon coupling at an arbitrary $\\mu$. This\nfeature is in contrast to the divergent behavior of an intravalley transverse\noptical phonon, which bears a close similarity to the polarization function\nrelevant to plasmons.",
        "positive": "Dipolar Ultrastrong Magnon-Magnon Coupling in a 3D Multilayered\n  Artificial Spin-Vortex Ice: Strongly-interacting nanomagnetic arrays are ideal systems for exploring\nreconfigurable magnonics. They provide huge microstate spaces and integrated\nsolutions for storage and neuromorphic computing alongside GHz functionality.\nThese systems may be broadly assessed by their range of reliably accessible\nstates and the strength of magnon coupling phenomena and nonlinearities.\n  Increasingly, nanomagnetic systems are expanding into three-dimensional\narchitectures. This has enhanced the range of available magnetic microstates\nand functional behaviours, but engineering control over 3D states and dynamics\nremains challenging.\n  Here, we introduce a 3D magnonic metamaterial composed from multilayered\nartificial spin ice nanoarrays. Comprising two magnetic layers separated by a\nnon-magnetic spacer, each nanoisland may assume four macrospin or vortex states\nper magnetic layer. This creates a system with a rich $16^N$ microstate space\nand intense static and dynamic dipolar magnetic coupling.\n  The system exhibits a broad range of emergent phenomena driven by the strong\ninter-layer dipolar interaction, including ultrastrong magnon-magnon coupling\nwith normalised coupling rates of $\\frac{\\Delta \\omega}{\\gamma} = 0.57$, GHz\nmode shifts in zero applied field and chirality-selective magneto-toroidal\nmicrostate programming and corresponding magnonic spectral control."
    },
    {
        "anchor": "Compressibility measurements of quasi-one-dimensional quantum wires: We report measurements of the compressibility of a one-dimensional (1D)\nquantum wire, defined in the upper well of a GaAs/AlGaAs double quantum well\nheterostructure. A wire defined simultaneously in the lower well probes the\nability of the upper wire to screen the electric field from a biased surface\ngate. The technique is sensitive enough to resolve spin-splitting of the\nsubbands in the presence of an in-plane magnetic field. We measure a\ncompressibility signal due to the 0.7 structure and study its evolution with\nincreasing temperature and magnetic field. We see no evidence of the formation\nof the quasibound state predicted by the Kondo model, instead our data are\nconsistent with theories which predict that the 0.7 structure arises as a\nresult of spontaneous spin polarization.",
        "positive": "Large quantum dots with small oscillator strength: We have measured the oscillator strength and quantum efficiency of excitons\nconfined in large InGaAs quantum dots by recording the spontaneous emission\ndecay rate while systematically varying the distance between the quantum dots\nand a semiconductor-air interface. The size of the quantum dots is measured by\nin-plane transmission electron microscopy and we find average in-plane\ndiameters of 40 nm. We have calculated the oscillator strength of excitons of\nthat size and predict a very large oscillator strength due to Coulomb effects.\nThis is in stark contrast to the measured oscillator strength, which turns out\nto be much below the upper limit imposed by the strong confinement model. We\nattribute these findings to exciton localization in local potential minima\narising from alloy intermixing inside the quantum dots."
    },
    {
        "anchor": "The single-atom box: bosonic staircase and effects of parity: We have developed a theory of a Josephson junction formed by two\ntunnel-coupled Bose-Einstein condensates in a double-well potential in the\nregime of strong atom-atom interaction for an arbitrary total number $N$ of\nbosons in the condensates. The tunnel resonances in the junction are shown to\nbe periodically spaced by the interaction energy, forming a single-atom\nstaircase sensitive to the parity of $N$ even for large $N$. One of the\nmanifestations of the staircase structure is the periodic modulation with the\nbias energy of the visibility of the interference pattern in lattices of\njunctions.",
        "positive": "Conductance of Tomonaga-Luttinger liquid wires and junctions with\n  resistances: We study the effect that resistive regions have on the conductance of a\nquantum wire with interacting electrons which is connected to Fermi liquid\nleads. Using the bosonization formalism and a Rayleigh dissipation function to\nmodel the power dissipation, we use both scattering theory and Green's function\ntechniques to derive the DC conductance. The resistive regions are generally\nfound to lead to incoherent transport. For a single wire, we find that the\nresistance adds in series to the contact resistance of h/e^2 for spinless\nelectrons, and the total resistance is independent of the Luttinger parameter\nK_W of the wire. We numerically solve the bosonic equations to illustrate what\nhappens when a charge density pulse is incident on the wire; the results depend\non the parameters of the resistive and interacting regions in interesting ways.\nFor a junction of Tomonaga-Luttinger liquid wires, we use a dissipationless\ncurrent splitting matrix to model the junction. For a junction of three wires\nconnected to Fermi liquid leads, there are two families of such matrices; we\nfind that the conductance matrix generally depends on K_W for one family but is\nindependent of K_W for the other family, regardless of the resistances present\nin the system."
    },
    {
        "anchor": "Low-frequency vortex dynamic susceptibility and relaxation in mesoscopic\n  ferromagnetic dots: Vortex dynamics in a restricted geometry is considered for a magnetic system\nconsisting of ferromagnetic cylindrical dots. To describe the vortex dynamic\nsusceptibility and relaxation the equation of motion for the vortex center\nposition is applied. The dependencies of the vortex dynamic susceptibility and\nresonance linewidth on geometrical parameters are calculated. A new method of\nextracting damping parameter from the vortex low-frequency resonance peaks is\nproposed and applied for interpretation of resonance data on FeNi circular\ndots.",
        "positive": "Emergent scale invariance of non-classical plasmons in graphene\n  nanoribbons: Using a nearest-neighbor tight-binding model we investigate quantum effects\nof plasmons on few-nanometer wide graphene nanoribbons, both for zigzag and\narmchair edge terminations. With insight from the Dirac description we find an\nemerging scale-invariant behavior that deviates from the classical model both\nfor zigzag and armchair structures. The onset of the deviation can be related\nto the position of the lowest parabolic band in the band structure. Dirac\ntheory is only valid in the parameter subspace where the scale invariance holds\nthat relates narrow ribbons with high doping to wide ribbons with low doping.\nWe also find that the edge states present in zigzag ribbons give rise to a\nblueshift of the plasmon, in contrast to earlier findings for graphene\nnanodisks and nanotriangles."
    },
    {
        "anchor": "High on-off conductance switching ratio in optically-driven\n  self-assembled conjugated molecular systems: A new azobenzene-thiophene molecular switch is designed, synthesized and used\nto form self-assembled monolayers (SAM) on gold. An \"on/off\" conductance ratio\nup to 7x1E3 (with an average value of 1.5x1E3) is reported. The \"on\"\nconductance state is clearly identified to the cis isomer of the azobenzene\nmoiety. The high \"on/off\" ratio is explained in terms of photo-induced,\nconfiguration-related, changes in the electrode-molecule interface energetics\n(changes in the energy position of the molecular orbitals with respect to the\nFermi energy of electrodes) in addition to changes in the tunnel barrier length\n(length of the molecules). First principles DFT calculations demonstrate a\nbetter delocalization of the frontier orbitals, as well as a stronger\nelectronic coupling between the azobenzene moiety and the electrode for the cis\nconfiguration over the trans one. Measured photoionization cross-sections for\nthe molecules in the SAM are close to the known values for azobenzene\nderivatives in solution.",
        "positive": "Tunable Fermi surface topology and Lifshitz transition in bilayer\n  graphene: Bilayer graphene is a highly tunable material: not only can one tune the\nFermi energy using standard gates, as in single-layer graphene, but the band\nstructure can also be modified by external perturbations such as transverse\nelectric fields or strain. We review the theoretical basics of the band\nstructure of bilayer graphene and study the evolution of the band structure\nunder the influence of these two external parameters. We highlight their key\nrole concerning the ease to experimentally probe the presence of a Lifshitz\ntransition, which consists in a change of Fermi contour topology as a function\nof energy close to the edges of the conduction and valence bands. Using a\ndevice geometry that allows the application of exceptionally high displacement\nfields, we then illustrate in detail the way to probe the topology changes\nexperimentally using quantum Hall effect measurements in a gapped bilayer\ngraphene system."
    },
    {
        "anchor": "Effective Magnetic Fields in Graphene Superlattices: We demonstrate that the electronic spectrum of graphene in a one-dimensional\nperiodic potential will develop a Landau level spectrum when the potential\nmagnitude varies slowly in space. The effect is related to extra Dirac points\ngenerated by the potential whose positions are sensitive to its magnitude. We\ndevelop an effective theory that exploits a chiral symmetry in the Dirac\nHamiltonian description with a superlattice potential, to show that the low\nenergy theory contains an effective magnetic field. Numerical diagonalization\nof the Dirac equation confirms the presence of Landau levels. Possible\nconsequences for transport are discussed.",
        "positive": "Strongly Correlated Fractional Quantum Hall Line Junctions: We have studied a clean finite-length line junction between interacting\ncounterpropagating single-branch fractional-quantum-Hall edge channels. Exact\nsolutions for low-lying excitations and transport properties are obtained when\nthe two edges belong to quantum Hall systems with different filling factors and\ninteract via the long-range Coulomb interaction. Charging effects due to the\ncoupling to external edge-channel leads are fully taken into account.\nConductances and power laws in the current-voltage characteristics of tunneling\nare strongly affected by inter-edge correlations."
    },
    {
        "anchor": "Exploring Event Horizons and Hawking Radiation through Deformed Graphene\n  Membranes: Analogue gravitational systems are becoming an increasing popular way of\nstudying the behaviour of quantum systems in curved spacetime. Setups based on\nultracold quantum gases in particular, have been recently harnessed to explore\nthe thermal nature of Hawking's and Unruh's radiation that was theoretically\npredicted almost 50 years ago. For solid state implementations, a promising\nsystem is graphene, in which a link between the Dirac-like low-energy\nelectronic excitations and relativistic quantum field theories has been\nunveiled soon after its discovery. Here we show that this link extends to the\ncase of curved quantum field theory when the graphene sheet is shaped in a\nsurface of constant negative curvature, known as Beltrami's pseudosphere.\nThanks to large-scale simulations, we provide numerical evidence that\nenergetically stable negative curvature graphene surfaces can be realized; the\nratio between the carbon-carbon bond length and the pseudosphere radius is\nsmall enough to allow the formation of an horizon; and the associated Local\nDensity Of States evaluated at horizon's proximity has a thermal nature with a\ncharacteristic temperature of few tens of Kelvin. Such findings pave the way to\nthe realization of a solid-state system in which the curved spacetime dynamics\nof quantum many body systems can be investigated.",
        "positive": "Aharonov-Bohm effect for pedestrian: When a magnetic field pierces a multiple-connected quantum system, the\ncorresponding wavefunction is altered although no net Lorentz force acts upon\nits carriers. This is the so called Aharonov-Bohm effect. The most simple\nmultiply-connected quantum system is a quantum ring QR. Nowadays it is possible\nto obtain QRs in the nanoscopic range providing spectroscopic data vs. and\napplied external magnetic field. We describe here the most significant quantum\neffects induced by the magnetic field in a QR by means of simple quantum\nmechanical models."
    },
    {
        "anchor": "Magnetic Field Response and Chiral Symmetry of Time Reversal Invariant\n  Topological Superconductors: We study the magnetic field response of the Majorana Kramers pairs of a\none-dimensional time-reversal invariant (TRI) superconductors (class DIII) with\nor without a coexisting chirality symmetry. For unbroken TR and chirality\ninvariance the parameter regimes for nontrivial values of the (Z_2)\nDIII-invariant and the (Z) chiral invariant coincide. However, broken TR may or\nmay not be accompanied by broken chirality, and if chiral symmetry is unbroken,\nthe pair of Majorana fermions (MFs) at a given end survives the loss of TR\nsymmetry in an entire plane perpendicular to the spin-orbit coupling field.\nConversely, we show that broken chirality may or may not be accompanied by\nbroken TR, and if TR is unbroken, the pair of MFs survives the loss of broken\nchirality. In addition to explaining the anomalous magnetic field response of\nall the DIII class TS systems proposed in the literature, we provide a\nrealistic route to engineer a \"true\" TR-invariant TS, whose pair of MFs at each\nend is split by an applied Zeeman field in arbitrary direction. We also prove\nthat, quite generally, the splitting of the MFs by TR-breaking fields in TRI\nsuperconductors is highly anisotropic in spin space, even in the absence of the\ntopological chiral symmetry.",
        "positive": "The influence of device geometry on many-body effects in quantum point\n  contacts: Signatures of the 0.7 anomaly, exchange and Kondo: The conductance of a quantum point contact (QPC) shows several features that\nresult from many-body electron interactions. The spin degeneracy in zero\nmagnetic field appears to be spontaneously lifted due to the so-called 0.7\nanomaly. Further, the g-factor for electrons in the QPC is enhanced, and a\nzero-bias peak in the conductance points to similarities with transport through\na Kondo impurity. We report here how these many-body effects depend on QPC\ngeometry. We find a clear relation between the enhanced g-factor and the\nsubband spacing in our QPCs, and can relate this to the device geometry with\nelectrostatic modeling of the QPC potential. We also measured the zero-field\nenergy splitting related to the 0.7 anomaly, and studied how it evolves into a\nsplitting that is the sum of the Zeeman effect and a field-independent exchange\ncontribution when applying a magnetic field. While this exchange contribution\nshows sample-to-sample fluctuations and no clear dependence on QPC geometry, it\nis for all QPCs correlated with the zero-field splitting of the 0.7 anomaly.\nThis provides evidence that the splitting of the 0.7 anomaly is dominated by\nthis field-independent exchange splitting. Signatures of the Kondo effect also\nshow no regular dependence on QPC geometry, but are possibly correlated with\nsplitting of the 0.7 anomaly."
    },
    {
        "anchor": "Anomalous Kondo effect of indirectly coupled double quantum dots: We report theoretical investigations of indirectly coupled double quantum\ndots (QD) side connected to an one-dimensional quantum wire. Due to quantum\ninterference controlled by the parameter $k_F L$, with $k_F$ the Fermi wave\nnumber of the wire and $L$ the distance between the two QDs, distinctly\ndifferent Kondo resonances are predicted depending on the range of $k_F L$. A\ntrue bound Kondo states is found while an anomalous Kondo resonance gives rise\nto both reduction and enhancement of conductance.",
        "positive": "Heat transport through a two-level system embedded between two harmonic\n  resonators: We investigate heat transport through an assembly consisting of a two-level\nsystem coupled between two harmonic oscillators, which is described by the\nquantum Rabi model, as a prototype of nanoscale heat devices using controllable\nmulti-level systems. Using the noninteracting-blip approximation (NIBA), we\nfind that the linear thermal conductance shows a characteristic temperature\ndependence with a two-peak structure. We also show that heat transport is\nsensitive to model parameters for weak system-bath coupling and strong\nhybridization between the two-level system and the harmonic oscillators. This\nproperty characteristic of the multi-level system is advantageous for\napplications such as a heat transistor, and can be examined in superconducting\ncircuits."
    },
    {
        "anchor": "Multiplicative topological semimetals: Exhaustive study of topological semimetal phases of matter in equilibriated\nelectonic systems and myriad extensions has built upon the foundations laid by\nearlier introduction and study of the Weyl semimetal, with broad applications\nin topologically-protected quantum computing, spintronics, and optical devices.\nWe extend recent introduction of multiplicative topological phases to find\npreviously-overlooked topological semimetal phases of electronic systems in\nequilibrium, with minimal symmetry-protection. We show these multiplicative\ntopological semimetal phases exhibit rich and distinctive bulk-boundary\ncorrespondence and response signatures that greatly expand understanding of\nconsequences of topology in condensed matter settings, such as the limits on\nFermi arc connectivity and structure, and transport signatures such as the\nchiral anomaly. Our work therefore lays the foundation for extensive future\nstudy of multiplicative topological semimetal phases.",
        "positive": "Hyperfine Structure of Transition Metal Defects in SiC: Transition metal (TM) defects in silicon carbide (SiC) are a promising\nplatform in quantum technology, especially because some TM defects emit in the\ntelecom band. We develop a theory for the interaction of an active electron in\nthe $D$-shell of a TM defect in SiC with the TM nuclear spin and derive the\neffective hyperfine tensor within the Kramers doublets formed by the spin-orbit\ncoupling. Based on our theory we discuss the possibility to exchange the\nnuclear and electron states with potential applications for nuclear spin\nmanipulation and long-lived nunclear-spin based quantum memories."
    },
    {
        "anchor": "Reduction of Interlayer Interaction in Multilayer Stacking Graphene with\n  Carbon Nanotube Insertion: Insights from Experiment and Simulation: The creation of multilayer graphene (Gr), while preserving the brilliant\nproperties of monolayer Gr derived from its unique band structure, can expand\nthe application field of Gr to the macroscale. However, the energy-favorable AB\nstacking structure in the multilayer Gr induces a strong interlayer interaction\nand alters the band structure. Consequently, the intrinsic properties of each\nmonolayer are degraded. In this work, we insert carbon nanotubes (CNTs) as\nnanospacers to modulate the microstructure of multilayer stacking Gr.\nNanospacers can increase the interlayer distance and reduce the interlayer\ninteraction. The Gr/CNT stacking structure is experimentally fabricated using a\ndry transfer method in a layer-by-layer manner. Raman spectroscopy verifies the\nreduction in the interlayer interaction within the stacking structure. Atomic\nforce microscopy shows an increase in the interlayer distance, which can\nexplain the weakening of the interlayer interactions. The microstructure of the\nstacked Gr and CNTs is studied by molecular dynamics simulation to\nsystematically investigate the effect of CNT insertion. We found that the\ndistribution distance, size, and arrangement of the CNT can modulate the\ninterlayer distance. These results will help us to understand and improve the\nproperties of the composite systems consisting of Gr and CNTs.",
        "positive": "Microcavity polaritons in disordered exciton lattices: We investigate the interaction of excitons in a two dimensional lattice and\nphotons in a planar cavity in the presence of disorder. The strong\nexciton-photon coupling is described in terms of polariton quasi-particles,\nwhich are scattered by a disorder potential. We consider three kinds of\ndisorder: (a) inhomogeneous exciton energy, (b) inhomogeneous exciton-photon\ncoupling and (c) deviations from an ideal lattice. These three types of\ndisorder are characteristic of different physical systems, and their separate\nanalysis gives insight on the competition between randomness and light-matter\ncoupling. We consider conventional planar polariton structures (with excitons\nresonant to photon modes emitting normal to the cavity) and Bragg polariton\nstructures, in which excitons in a lattice are resonant with photon modes at a\nfinite angle satisfying the Bragg condition. We calculate the absorption\nspectra in the normal direction and at the Bragg angle by a direct\ndiagonalization of the exciton-photon Hamiltonian. We found that in some cases\nweak disorder increases the light-matter coupling and leads to a larger\npolariton splitting. Moreover, we found that the coupling of excitons and\nphotons is less sensitive to disorder of type (b) and (c). This suggests that\npolaritonic structures realized with impurities in a semiconductor or with\natoms in optical lattices are good candidate for the observation of some of the\nBragg polariton features."
    },
    {
        "anchor": "Spin-Cherenkov effect in a magnetic nanostrip with interfacial\n  Dzyaloshinskii-Moriya interaction: Spin-Cherenkov effect enables strong excitations of spin waves (SWs) with\nnonlinear wave dispersions. The Dzyaloshinskii-Moriya interaction (DMI) results\nin anisotropy and nonreciprocity of SWs propagation. In this work, we study the\neffect of the interfacial DMI on SW Cherenkov excitations in permalloy\nthin-film strips within the framework of micromagnetism. By performing\nmicromagnetic simulations, it is shown that coherent SWs are excited when the\nvelocity of a moving magnetic source exceeds the propagation velocity of the\nSWs. Moreover, the threshold velocity of the moving magnetic source with finite\nDMI can be reduced compared to the case of zero DMI. It thereby provides a\npromising route towards efficient SW generation and propagation, with potential\napplications in spintronic and magnonic devices.",
        "positive": "Fano resonances and decoherence in transport through quantum dots: A tunable microwave scattering device is presented which allows the\ncontrolled variation of Fano line shape parameters in transmission through\nquantum billiards. We observe a non-monotonic evolution of resonance parameters\nthat is explained in terms of interacting resonances. The dissipation of\nradiation in the cavity walls leads to decoherence and thus to a modification\nof the Fano profile. We show that the imaginary part of the complex Fano\nq-parameter allows to determine the absorption constant of the cavity. Our\ntheoretical results demonstrate further that the two decohering mechanisms,\ndephasing and dissipation, are equivalent in terms of their effect on the\nevolution of Fano resonance lineshapes."
    },
    {
        "anchor": "Zero-bias anomaly in one-dimensional tunneling contacts: We study the Coulomb interaction effects on the tunneling conductance of a\ncontact constructed of two parallel quantum wires. The following contacts are\nconsidered: two clean identical quantum wires, two disordered identical quantum\nwires, and asymmetric contact of one clean and another disordered quantum\nwires. We show that the low-voltage anomaly of the tunneling conductance is\nless singular than the low-energy anomaly of the one-particle density of\nstates.",
        "positive": "Ground-state quantum geometry in superconductor-quantum dot chains: Multiterminal Josephson junctions constitute engineered topological systems\nin arbitrary synthetic dimensions defined by the superconducting phases.\nMicrowave spectroscopy enables the measurement of the quantum geometric tensor,\na fundamental quantity describing both the quantum geometry and the topology of\nthe emergent Andreev bound states in a unified manner. In this work we propose\nan experimentally feasible multiterminal setup of $N$ quantum dots connected to\n$N+1$ superconducting leads to study nontrivial topology in terms of the\nmany-body Chern number of the ground state. Moreover, we generalize the\nmicrowave spectroscopy scheme to the multiband case and show that the elements\nof the quantum geometric tensor of the noninteracting ground state can be\nexperimentally accessed from the measurable oscillator strengths at low\ntemperature."
    },
    {
        "anchor": "Record Low Thermal Conductivity of Polycrystalline MoS2 films: Tuning\n  the Thermal Conductivity by Grain Orientation: We report a record low thermal conductivity in polycrystalline MoS2 obtained\nby varying grain sizes and orientations in ultrathin films. By optimizing the\nsulphurisation parameters of nanometre-thick Mo layer, we could grow MoS2 films\nwith tuneable morphologies. The thermal conductivity is extracted from a Raman\nlaser power-dependent study on suspended samples. The lowest value of thermal\nconductivity of 0.27 Wm-1K-1, which reaches a similar value as teflon, is\nobtained in a polycrystalline sample formed by a combination of horizontally\nand vertically oriented grains, with respect to the bulk (001) monocrystal.\nAnalysis by means of molecular dynamics and finite element method simulations\nconfirm that such grain arrangement leads to lower grain boundary conductance.\nWe discuss the possible use of these thermal insulating films in the context of\nelectronics and thermoelectricity.",
        "positive": "The Einstein - de Haas effect at radio frequencies in and near magnetic\n  equilibrium: The Einstein-de Haas (EdH) effect and its reciprocal the Barnett effect are\nfundamental to magnetism and uniquely yield measures of the ratio of magnetic\nmoment to total angular momentum. These effects, small and generally difficult\nto observe, are enjoying a resurgence of interest as contemporary techniques\nenable new approaches to their study. The high mechanical resonance frequencies\nin nanomechanical systems offer a tremendous advantage for the observation of\nEdH torques in particular. At radio frequencies, the EdH effect can become\ncomparable to or even exceed in magnitude conventional cross-product magnetic\ntorques. In addition, the RF-EdH torque is expected to be phase-shifted by 90\ndegrees relative to cross-product torques, provided the magnetic system remains\nin quasi-static equilibrium, enabling separation in quadratures when both\nsources of torque are operative. Radio frequency EdH measurements are\ndemonstrated through the full hysteresis range of micrometer scale,\nmonocrystalline yttrium iron garnet (YIG) disks. Equilibrium behavior is\nobserved in the vortex state at low bias field. Barkhausen-like features emerge\nin the in-plane EdH torque at higher fields in the vortex state, revealing\nmagnetic disorder too weak to be visible through the in-plane cross-product\ntorque. Beyond vortex annihilation, peaks arise in the EdH torque versus bias\nfield, and these together with their phase signatures indicate additional\nutility of the Einstein-de Haas effect for the study of RF-driven spin\ndynamics."
    },
    {
        "anchor": "Charge fluctuations of a Cr atom probed in the optical spectra of a\n  quantum dot: We study the emission of individual quantum dots in CdTe/ZnTe samples doped\nwith a low concentration of Cr. In addition to dots with a photoluminescence\n(PL) split by the exchange interaction with a magnetic Cr atom, we observe\nanother type of dots with a complex PL structure composed of a minimum of six\nlines on the exciton and biexciton and three lines on the charged excitons. In\nthese dots, the linear polarization dependence and the magnetic field\ndependence of the PL behave like three similar quantum dots emitting at\nslightly different energies. Cross-correlation intensity measurements show that\nthese emission lines are not independent but exchange intensities in a time\nscale of a few hundred nanoseconds depending on the optical excitation power.\nWe attribute this PL structure to charge fluctuations of a Cr atom located in\nthe vicinity the CdTe dots in the ZnTe barrier. We present a model which\nconfirms that the presence of a single charge fluctuating between -e\n(Cr$^{+}$), 0 (Cr$^{2+}$) and +e (Cr$^{3+}$) and located a few nm away from the\ndot explains the observation of three emission energies. We finally show that\nthe interaction between the confined carriers and the nearby fluctuating\nlocalized charge can be modified by an applied static electric field which\nmodulates the splitting of the emission lines.",
        "positive": "On-Chip Cavity Optomechanical Coupling: On-chip cavity optomechanics, in which strong co-localization of light and\nmechanical motion is engineered, relies on efficient coupling of light both\ninto and out of the on-chip optical resonator. Here we detail our particular\nstyle of tapered and dimpled optical fibers, pioneered by the Painter group at\nCaltech, which are a versatile and reliable solution to efficient on-chip\ncoupling. First, a brief overview of tapered, single mode fibers is presented,\nin which the single mode cutoff diameter is highlighted. The apparatus used to\ncreate a dimpled tapered fiber is then described, followed by a comprehensive\naccount of the procedure by which a dimpled tapered fiber is produced and\nmounted in our system. The custom-built optical access vacuum chambers in which\nour on-chip optomechanical measurements are performed are then discussed.\nFinally, the process by which our optomechanical devices are fabricated and the\nmethod by which we explore their optical and mechanical properties is\nexplained. It is our expectation that this manuscript will enable the novice to\ndevelop advanced optomechanical experiments."
    },
    {
        "anchor": "Temperature Induced Shifts of Yu-Shiba-Rusinov Resonances in\n  Nanowire-Based Hybrid Quantum Dots: The strong coupling of a superconductor to a spinful quantum dot results in\nYu-Shiba-Rusinov (YSR) discrete subgap excitations. In isolation and at zero\ntemperature, the excitations are $\\delta$ resonances. In transport experiments,\nhowever, they show as broad differential conductance peaks. We obtain the\nlineshape of the peaks and their temperature dependence in\nsuperconductor-quantum-dot-metal (S-QD-N) nanowire-based devices. Unexpectedly,\nwe find that the peaks shift in energy with temperature, with the shift\nmagnitude and sign depending on ground state parity and bias voltage.\nAdditionally, we empirically find a power-law scaling of the peak area versus\ntemperature. These observations are not explained by current models.",
        "positive": "Spin-flip transitions induced by time-dependent electric fields in\n  surfaces with strong spin-orbit interaction: We present a comprehensive theoretical investigation of the light absorption\nrate at the Pb/Ge(111) surface with strong spin-orbit coupling. Our\ncalculations show that electron spin-flip transitions cause as much as 6% of\nthe total light absorption, representing one order of magnitude enhancement\nover Rashba-like systems. Thus, it is demonstrated that a substantial part of\nthe light irradiating this nominally non-magnetic surface is attenuated in spin\nflip processes. Remarkably, the spin-flip transition probability is structured\nin well defined hot spots within the Brillouin zone where the electron spin\nexperiences a sudden 90 degree rotation. This mechanism offers the possibility\nof an experimental approach to the spin-orbit phenomena by optical means."
    },
    {
        "anchor": "Integer Spin Hall Effect in Ballistic Quantum Wires: We investigate the ballistic electron transport in a two dimensional Quantum\nWire under the action of an electric field ($E_y$). We demonstrate how the\npresence of a Spin Orbit coupling, due to the uniform electric confinement\nfield gives a non-commutative effect as in the presence of a transverse\nmagnetic field.\n  We discuss how the non commutation implies an edge localization of the\ncurrents depending on the electron spins also giving a semi-classical spin\ndependent Hall current.\n  We also discuss how it is possible obtain a quantized Spin Hall conductance\nin the ballistic transport regime by developing the Landauer formalism and show\nthe coupling between the spin magnetic momentum and the orbital one due to the\npresence of a circulating current.",
        "positive": "Entanglement and Bell States in Superconducting Flux Qubits: We theoretically study macroscopic quantum entanglement in two\nsuperconducting flux qubits. To manipulate the state of two flux qubits, a\nJosephson junction is introduced in the connecting loop coupling the qubits.\nIncreasing the coupling energy of the Josephson junction makes it possible to\nachieve relatively strong coupling between the qubits, causing two-qubit\ntunneling processes even dominant over the single-qubit tunneling process in\nthe states of two qubits. It is shown that due to the two-qubit tunneling\nprocesses both the ground state and excited state of the coupled flux qubits\ncan be a Bell type state, maximally entangled. The parameter regimes for the\nBell states are discussed in terms of magnetic flux and Josephson coupling\nenergies."
    },
    {
        "anchor": "Scaling behavior of spin transport in hydrogenated graphene: We calculate the spin transport of hydrogenated graphene using the\nLandauer-B\\\"uttiker formalism with a spin-dependent tight-binding Hamiltonian.\nThe advantages of using this method is that it simultaneously gives information\non sheet resistance and localization length as well as spin relaxation length.\nFurthermore, the Landauer-B\\\"uttiker formula can be computed very efficiently\nusing the recursive Green's function technique. Previous theoretical results on\nspin relaxation time in hydrogenated graphene have not been in agreement with\nexperiments. Here, we study magnetic defects in graphene with randomly aligned\nmagnetic moments, where interference between spin-channels is explicitly\nincluded. We show that the spin relaxation length and sheet resistance scale\nnearly linearly with the impurity concentration. Moreover, the spin relaxation\nmechanism in hydrogenated graphene is Markovian only near the charge neutrality\npoint or in the highly dilute impurity limit.",
        "positive": "Probing the exchange field of a quantum-dot spin valve by a\n  superconducting lead: Electrons in a quantum-dot spin valve, consisting of a single-level quantum\ndot coupled to two ferromagnetic leads with magnetizations pointing in\narbitrary directions, experience an exchange field that is induced on the dot\nby the interplay of Coulomb interaction and quantum fluctuations. We show that\na third, superconducting lead with large superconducting gap attached to the\ndot probes this exchange field very sensitively. In particular, we find\nstriking signatures of the exchange field in the symmetric component of the\nsupercurrent with respect to the bias voltage applied between the ferromagnets\nalready for small values of the ferromagnets' spin polarization."
    },
    {
        "anchor": "Ultrafast carriers' separation imaging in WS2-WSe2 in plane\n  heterojunction by transient reflectivity microscopy: Carrier transport in nanodevices plays a crucial role in determining their\nfunctionality. In the post-Moore era, the behavior of carriers near surface or\ninterface domains the function of the whole devices. However, the femtosecond\ndynamics and nanometer-scale movement of carriers pose challenges for imaging\ntheir behavior. Techniques with high spatial-temporal resolution become\nimperative for tracking their intricate dynamics. In this study, we employed\ntransient reflectivity microscopy to directly visualize the charge separation\nin the atomic interface of WS2-WSe2 in-plane heterojunctions. The carriers'\ndrifting behavior was carefully tracked, enabling the extraction of drift\nvelocities of 30 nm/ps and 10.6 nm/ps for electrons and holes. Additionally,\nthe width of the depletion layer was determined to be 300 nm based on the\ncarriers' moving trajectory. This work provides essential parameters for the\npotential effective utilization of these covalent in-plane heterojunctions,and\ndemonstrates the success of transient optical imaging in unraveling the\nelectrical behavior of nano devices, paving the way for a new avenue of\nelectro-optical analysis.",
        "positive": "Room temperature ferromagnetism and anomalous Hall effect in\n  Si_{1-x}Mn_x (x = 0.35) alloys: A detailed study of the magnetic and transport properties of Si1-xMnx (X =\n0.35) films is presented. We observe the anomalous Hall effect (AHE) in these\nfilms up to room temperature. The results of the magnetic measurements and the\nAHE data are consistent and demonstrate the existence of long-range\nferromagnetic (FM) order in the systems under study. A correlation of the AHE\nand the magnetic properties of Si1-xMnx (X = 0.35) films with their\nconductivity and substrate type is shown. A theoretical model based on the idea\nof a two-phase magnetic material, in which molecular clusters with localized\nmagnetic moments are embedded in the matrix of a weak itinerant ferromagnet, is\ndiscussed. The long-range ferromagnetic order at high temperatures is mainly\ndue to the Stoner enhancement of the exchange coupling between clusters through\nthermal spin fluctuations (\"paramagnons\") in the matrix. Theoretical\npredictions and experimental data are in good qualitative agreement."
    },
    {
        "anchor": "Dimensional crossover and enhanced thermoelectric efficiency due to\n  broken symmetry in graphene antidot lattices: Graphene antidot lattices (GALs) are two-dimensional (2D) monolayers with\nperiodically placed holes in otherwise pristine graphene. We investigate the\nelectronic properties of symmetric and asymmetric GAL structures having\nhexagonal holes, and show that anisotropic 2D GALs can display a dimensional\ncrossover such that effectively one-dimensional (1D) electronic structures can\nbe realized in two-dimensions around the charge neutrality point. We\ninvestigate the transport and thermoelectric properties of these 2D GALs by\nusing non-equilibrium Green function (NEGF) method. Dimensional crossover\nmanifests itself as transmission plateaus, a characteristic feature of 1D\nsystems, and enhancement of thermoelectric efficiency, where thermoelectric\nfigure of merit, $zT$, can be as high as 0.9 at room temperature. We also study\nthe transport properties in the presence of Anderson disorder and find that\nmean free paths of effectively 1D electrons of anisotropic configuration are\nmuch longer than their isotropic counterparts. We further argue that\ndimensional crossover due to broken symmetry and enhancement of thermoelectric\nefficiency can be nanostructuring strategy virtually for all 2D materials.",
        "positive": "Coulomb blockade in an atomically thin quantum dot coupled to a tunable\n  Fermi reservoir: Gate-tunable quantum-mechanical tunnelling of particles between a quantum\nconfined state and a nearby Fermi reservoir of delocalized states has\nunderpinned many advances in spintronics and solid-state quantum optics. The\nprototypical example is a semiconductor quantum dot separated from a gated\ncontact by a tunnel barrier. This enables Coulomb blockade, the phenomenon\nwhereby electrons or holes can be loaded one-by-one into a quantum dot.\nDepending on the tunnel-coupling strength, this capability facilitates single\nspin quantum bits or coherent many-body interactions between the confined spin\nand the Fermi reservoir. Van der Waals (vdW) heterostructures, in which a wide\nrange of unique atomic layers can easily be combined, offer novel prospects to\nengineer coherent quantum confined spins, tunnel barriers down to the atomic\nlimit or a Fermi reservoir beyond the conventional flat density of states.\nHowever, gate-control of vdW nanostructures at the single particle level is\nneeded to unlock their potential. Here we report Coulomb blockade in a vdW\nheterostructure consisting of a transition metal dichalcogenide quantum dot\ncoupled to a graphene contact through an atomically thin hexagonal boron\nnitride (hBN) tunnel barrier. Thanks to a tunable Fermi reservoir, we can\ndeterministically load either a single electron or a single hole into the\nquantum dot. We observe hybrid excitons, composed of localized quantum dot\nstates and delocalized continuum states, arising from ultra-strong\nspin-conserving tunnel coupling through the atomically thin tunnel barrier.\nProbing the charged excitons in applied magnetic fields, we observe large\ngyromagnetic ratios (~8). Our results establish a foundation for engineering\nnext-generation devices to investigate either novel regimes of Kondo physics or\nisolated quantum bits in a vdW heterostructure platform."
    },
    {
        "anchor": "Coherent electron transport by adiabatic passage in an imperfect donor\n  chain: Coherent Tunneling Adiabatic Passage (CTAP) has been proposed as a long-range\nphysical qubit transport mechanism in solid-state quantum computing\narchitectures. Although the mechanism can be implemented in either a chain of\nquantum dots or donors, a 1D chain of donors in Si is of particular interest\ndue to the natural confining potential of donors that can in principle help\nreduce the gate densities in solid-state quantum computing architectures. Using\ndetailed atomistic modeling, we investigate CTAP in a more realistic triple\ndonor system in the presence of inevitable fabrication imperfections. In\nparticular, we investigate how an adiabatic pathway for CTAP is affected by\ndonor misplacements, and propose schemes to correct for such errors. We also\ninvestigate the sensitivity of the adiabatic path to gate voltage fluctuations.\nThe tight-binding based atomistic treatment of straggle used here may benefit\nunderstanding of other donor nanostructures, such as donor-based charge and\nspin qubits. Finally, we derive an effective 3 \\times 3 model of CTAP that\naccurately resembles the voltage tuned lowest energy states of the\nmulti-million atom tight-binding simulations, and provides a translation\nbetween intensive atomistic Hamiltonians and simplified effective Hamiltonians\nwhile retaining the relevant atomic-scale information. This method can help\ncharacterize multi-donor experimental structures quickly and accurately even in\nthe presence of imperfections, overcoming some of the numeric intractabilities\nof finding optimal eigenstates for non-ideal donor placements.",
        "positive": "Discrete charging of metallic grains: Statistics of addition spectra: We analyze the statistics of electrostatic energies (and their differences)\nfor a quantum dot system composed of a finite number $K$ of electron islands\n(metallic grains) with random capacitance-inductance matrix $C$, for which the\ntotal charge is discrete, $Q=Ne$ (where $e$ is the charge of an electron and\n$N$ is an integer). The analysis is based on a generalized charging model,\nwhere the electrons are distributed among the grains such that the\nelectrostatic energy E(N) is minimal. Its second difference (inverse\ncompressibility) $\\chi_{N}=E(N+1)-2 E(N)+E(N-1)$ represents the spacing between\nadjacent Coulomb blockade peaks appearing when the conductance of the quantum\ndot is plotted against gate voltage. The statistics of this quantity has been\nthe focus of experimental and theoretical investigations during the last two\ndecades. We provide an algorithm for calculating the distribution function\ncorresponding to $\\chi_{N}$ and show that this function is piecewise\npolynomial."
    },
    {
        "anchor": "Perturbative spectrum of Trapped Weakly Interacting Bosons in Two\n  Dimensions: We study a trapped Bose-Einstein condensate under rotation in the limit of\nweak, translational and rotational invariant two-particle interactions. We use\nthe perturbation-theory approach (the large-N expansion) to calculate the\nground-state energy and the excitation spectrum in the asymptotic limit where\nthe total number of particles N goes to infinity while keeping the total\nangular momentum L finite. Calculating the probabilities of different\nconfigurations of angular momentum in the exact eigenstates gives us a clear\nview of the physical content of excitations. We briefly discuss the case of\nrepulsive contact interaction.",
        "positive": "Local Topological Markers in Odd Spatial Dimensions and Their\n  Application to Amorphous Topological Matter: Local topological markers, topological invariants evaluated by local\nexpectation values, are valuable for characterizing topological phases in\nmaterials lacking translation invariance. The Chern marker -- the Chern number\nexpressed in terms of the Fourier transformed Chern character -- is an easily\napplicable local marker in even dimensions, but there are no analogous\nexpressions for odd dimensions. We provide general analytic expressions for\nlocal markers for free-fermion topological states in odd dimensions protected\nby local symmetries: a Chiral marker, a local $\\mathbb Z$ marker which in case\nof translation invariance is equivalent to the chiral winding number, and a\nChern-Simons marker, a local $\\mathbb Z_2$ marker characterizing all nonchiral\nphases in odd dimensions. We achieve this by introducing a one-parameter family\n$P_{\\vartheta}$ of single-particle density matrices interpolating between a\ntrivial state and the state of interest. By interpreting the parameter\n$\\vartheta$ as an additional dimension, we calculate the Chern marker for the\nfamily $P_{\\vartheta}$. We demonstrate the practical use of these markers by\ncharacterizing the topological phases of two amorphous Hamiltonians in three\ndimensions: a topological superconductor ($\\mathbb Z$ classification) and a\ntopological insulator ($\\mathbb Z_2$ classification)."
    },
    {
        "anchor": "Microgap thermophotovoltaic systems with low emission temperature and\n  high electric output: We theoretically show that a thermophotovoltaic (TPV) system enhanced by a\nwire metamaterial opens the door to a prospective microgap thermophotovoltaics\nwhich will combine high electric output with relatively low temperatures of the\nemitter. The suggested system comprises an array of parallel metal nanowires\ngrown on top of a photovoltaic semiconductor and standing free in the vacuum\ngap between the host dielectric layer and the emitter, so that their ends are\nsufficiently close to the emitting surface. Due to the resonant near-field\ncoupling between this wire medium and the emitter and due to the optimized\nlayered structure of the whole system, the strongly super-Planckian radiative\nheat flux of resonant nature is engineered.",
        "positive": "Tuning the polarized quantum phonon transmission in graphene nanoribbons: We propose systems that allow a tuning of the phonon transmission function\nT($\\omega$) in graphene nanoribbons by using C$^{13}$ isotope barriers, antidot\nstructures, and distinct boundary conditions. Phonon modes are obtained by an\ninteratomic fifth-nearest neighbor force-constant model (5NNFCM) and\nT($\\omega$) is calculated using the non-equilibrium Green's function formalism.\nWe show that by imposing partial fixed boundary conditions it is possible to\nrestrict contributions of the in-plane phonon modes to T($\\omega$) at low\nenergy. On the contrary, the transmission functions of out-of-plane phonon\nmodes can be diminished by proper antidot or isotope arrangements. In\nparticular, we show that a periodic array of them leads to sharp dips in the\ntransmission function at certain frequencies $\\omega_{\\nu}$ which can be\npre-defined as desired by controlling their relative distance and size. With\nthis, we demonstrated that by adequate engineering it is possible to govern the\nmagnitude of the ballistic transmission functions T$(\\omega)$ in graphene\nnanoribbons. We discuss the implications of these results in the design of\ncontrolled thermal transport at the nanoscale as well as in the enhancement of\nthermo-electric features of graphene-based materials."
    },
    {
        "anchor": "Disordered weak and strong topological insulators: A global phase diagram of disordered weak and strong topological insulators\nis established numerically. As expected, the location of the phase boundaries\nis renormalized by disorder, a feature recognized in the study of the so-called\ntopological Anderson insulator. Here, we report unexpected quantization, i.e.,\nrobustness against disorder of the conductance peaks on these phase boundaries.\nAnother highlight of the work is on the emergence of two subregions in the weak\ntopological insulator phase under disorder. According to the size dependence of\nthe conductance, the surface states are either robust or \"defeated\" in the two\nsubregions. The nature of the two distinct types of behavior is further\nrevealed by studying the Lyapunov exponents.",
        "positive": "Thermal spin photonics in the near-field of nonreciprocal media: The interplay of spin angular momentum and thermal radiation is a frontier\narea of interest to nanophotonics as well as topological physics. Here, we show\nthat a thick planar slab of a nonreciprocal material, despite being at thermal\nequilibrium with its environment, can exhibit nonzero photon spin angular\nmomentum and nonzero radiative heat flux in its vicinity. We identify them as\nthe persistent thermal photon spin (PTPS) and the persistent planar heat\ncurrent (PPHC) respectively. With a practical example system, we reveal that\nthe fundamental origin of these phenomena is connected to spin-momentum locking\nof thermally excited evanescent waves. We also discover spin magnetic moment of\nsurface polaritons in nonreciprocal photonics that further clarifies these\nfeatures. We then propose a novel thermal photonic imaging experiment based on\nBrownian motion that allows one to witness these surprising features by\ndirectly looking at them using a lab microscope. We further demonstrate the\nuniversal behavior of these near-field thermal radiation phenomena through a\ncomprehensive analysis of gyroelectric, gyromagnetic and magneto-electric\nnonreciprocal materials. Together, these results expose a surprisingly little\nexplored research area of thermal spin photonics with prospects for new avenues\nrelated to non-Hermitian topological photonics and radiative heat transport."
    },
    {
        "anchor": "Giant Valley-Zeeman Splitting from Spin-Singlet and Spin-Triplet\n  Interlayer Excitons in WSe2/MoSe2 Heterostructure: Transition metal dichalcogenides (TMDCs) heterostructure with a type II\nalignment hosts unique interlayer excitons with the possibility of spin-triplet\nand spin-singlet states. However, the associated spectroscopy signatures remain\nelusive, strongly hindering the understanding of the Moire potential modulation\nof the interlayer exciton. In this work, we unambiguously identify the\nspin-singlet and spin-triplet interlayer excitons in the WSe2/MoSe2\nhetero-bilayer with a 60-degree twist angle through the gate- and magnetic\nfield-dependent photoluminescence spectroscopy. Both the singlet and triplet\ninterlayer excitons show giant valley-Zeeman splitting between the K and K'\nvalleys, a result of the large Lande g-factor of the singlet interlayer exciton\nand triplet interlayer exciton, which are experimentally determined to be ~\n10.7 and ~ 15.2, respectively, in good agreement with theoretical expectation.\nThe PL from the singlet and triplet interlayer excitons show opposite\nhelicities, determined by the atomic registry. Helicity-resolved\nphotoluminescence excitation (PLE) spectroscopy study shows that both singlet\nand triplet interlayer excitons are highly valley-polarized at the resonant\nexcitation, with the valley polarization of the singlet interlayer exciton\napproaches unity at ~ 20 K. The highly valley-polarized singlet and triplet\ninterlayer excitons with giant valley-Zeeman splitting inspire future\napplications in spintronics and valleytronics.",
        "positive": "Shubnikov-de Haas-like Quantum Oscillations in Artificial\n  One-Dimensional LaAlO3/SrTiO3 Electron Channels: The widely reported magnetoresistance oscillations in LaAlO3/SrTiO3\nheterostructures have invariably been attributed to the Shubnikov-de Haas (SdH)\neffect, despite a pronounced inconsistency with low-field Hall resistance\nmeasurements. Here we report SdH-like resistance oscillations in quasi-1D\nelectron waveguides created at the LaAlO3/SrTiO3 interface by conductive atomic\nforce microscopy lithography. These oscillations can be directly attributed to\nmagnetic depopulation of magnetoelectric subbands. Our results suggest that the\nSdH oscillations in 2D SrTiO3-based systems may originate from naturally\nforming quasi-1D channels."
    },
    {
        "anchor": "The Nielsen-Ninomiya theorem, PT-invariant non-Hermiticity and single\n  8-shaped Dirac cone: The Nielsen-Ninomiya theorem implies that any local, Hermitian and\ntranslationally invariant lattice action in even-dimensional spacetime possess\nan equal number of left- and right-handed chiral fermions. We argue that if one\nsacrifices the property of Hermiticity while keeping the locality and\ntranslation invariance, while imposing invariance of the action under the\nspace-time (PT) reversal symmetry, then the excitation spectrum of the theory\nmay contain a non-equal number of left- and right-handed massless fermions with\nreal-valued dispersion. We illustrate our statement in a simple 1+1 dimensional\nlattice model which exhibits a skewed 8-figure patterns in its energy spectrum.\nA drawback of the model is that the PT symmetry of the Hamiltonian is\nspontaneously broken implying that the energy spectrum contains complex\nbranches. We also demonstrate that the Dirac cone is robust against local\ndisorder so that the massless excitations in this PT-invariant model are not\ngapped by random space-dependent perturbations in the couplings.",
        "positive": "X-Ray Analysis of Oxygen-induced Perpendicular Magnetic Anisotropy in\n  Pt/Co/AlOx trilayer: X-ray spectroscopy measurements have been performed on a series of Pt/Co/AlOx\ntrilayers to investigate the role of Co oxidation in the perpendicular magnetic\nanisotropy of the Co/AlOx interface. It is observed that high temperature\nannealing modifies the magnetic properties of the Co layer, inducing an\nenhancement of the perpendicular magnetic anisotropy. The microscopic\nstructural properties are analyzed via X-ray Absorption Spectroscopy, X-ray\nMagnetic Circular Dichroism and X-ray Photoelectron Spectroscopy measurements.\nIt is shown that annealing enhances the amount of interfacial oxide, which may\nbe at the origin of a strong perpendicular magnetic anisotropy."
    },
    {
        "anchor": "Interface reflectivity of a superdiffusive spin current in ultrafast\n  demagnetization and THz emission: The spin- and energy-dependent interface reflectivity of a ferromagnetic (FM)\nfilm in contact with a nonmagnetic (NM) film is calculated using a\nfirst-principles transport method and incorporated into the superdiffusive spin\ntransport model to study the femtosecond laser-induced ultrafast\ndemagnetization of Fe|NM and Ni|NM (NM= Au, Al & Pt) bilayers. By comparing the\ncalculated demagnetization with transparent and real interfaces, we demonstrate\nthat the spin-dependent reflection of hot electrons has a noticeable influence\non the ultrafast demagnetization and the associated terahertz electromagnetic\nradiation. In particular, a spin filtering effect is found at the Fe|NM\ninterface that increases the spin current injected into the NM metal, which\nenhances both the resulting demagnetization and the resulting THz emission.\nThis suggests that the THz radiation can be optimized by tailoring the\ninterface, indicating a very large tunability.",
        "positive": "Random Rashba spin-orbit coupling at the quantum spin Hall edge: We study a one-dimensional helical system with random Rashba spin-orbit\ncoupling. Using renor- malization group methods, we derive a consistent set of\nflow equations governing the important con- trol parameters of the\nbackscattering process. Thereby, we prove the existence of disorder-induced\ntwo-particle backscattering that can even be non-local in space. This analysis\nallows us to derive the scaling form of the conductance at low temperatures. We\nfind that two-particle backscattering due to random spin-orbit coupling differs\nfrom the one off a single Rashba impurity by both the scaling of the\nconductance with the temperature and the relevance of the backscattering\noperators."
    },
    {
        "anchor": "Imaging Localized States in Graphene Nanostructures: Probing techniques with spatial resolution have the potential to lead to a\nbetter understanding of the microscopic physical processes and to novel routes\nfor manipulating nanostructures. We present scanning-gate images of a graphene\nquantum dot which is coupled to source and drain via two constrictions. We\nimage and locate conductance resonances of the quantum dot in the\nCoulomb-blockade regime as well as resonances of localized states in the\nconstrictions in real space.",
        "positive": "Magnetic control of the valley degree of freedom of massive Dirac\n  fermions with application to transition metal dichalcogenides: We study the valley-dependent magnetic and transport properties of massive\nDirac fermions in multivalley systems such as the transition metal\ndichalcogenides. The asymmetry of the zeroth Landau level between valleys and\nthe enhanced magnetic susceptibility can be attributed to the different orbital\nmagnetic moment tied with each valley. This allows the valley polarization to\nbe controlled by tuning the external magnetic field and the doping level. As a\nresult of this magnetic field induced valley polarization, there exists an\nextra contribution to the ordinary Hall effect. All these effects can be\ncaptured by a low energy effective theory with a valley-orbit coupling term."
    },
    {
        "anchor": "Resonant transmission through an open quantum dot: We have measured the low-temperature transport properties of a quantum dot\nformed in a one-dimensional channel. In zero magnetic field this device shows\nquantized ballistic conductance plateaus with resonant tunneling peaks in each\ntransition region between plateaus. Studies of this structure as a function of\napplied perpendicular magnetic field and source-drain bias indicate that\nresonant structure deriving from tightly bound states is split by Coulomb\ncharging at zero magnetic field.",
        "positive": "Floquet spectrum and electronic transitions of tilted anisotropic Dirac\n  materials under electromagnetic radiation: monodromy matrix approach: We analyze the quasienergy-spectrum and the valence to conduction-band\ntransition probabilities of a tilted anisotropic Dirac material subject to\nlinearly and circularly polarized electromagnetic fields. The\nquasienergy-spectrum is numerically calculated from the monodromy matrix of the\nSchr\\\"odinger equation via the Floquet theorem for arbitrarily intense\nelectromagnetic fields. To asses the valence to conduction-band transition\ntimes we deduced a Rabi-like formula in the rotating wave approximation. In the\nstrong-field regime the spectrum as a function of the momentum components\ndivides into two very distinctive regions. In the first, located around the\nDirac point, the quasi-spectrum is significantly distorted by the field as the\nelectronic parameters are renormalized by electronic-dressing. In the second,\nall the characteristics of the free carrier spectrum are retained. Linearly\npolarized light anisotropically deforms the spectrum according to the field\npolarization direction. Dirac-like points form around the original Dirac point.\nThe quasi spectrum of circularly polarized light, instead, exhibits a gap\nformation in the Dirac point and has elliptical symmetry. We show that, in\ncontrast to the single-photon resonant transitions that characterize the\nweak-field regime, the strong-field regime is dominated by multiphoton\nresonances."
    },
    {
        "anchor": "Valley-dependent spin transport in monolayer transition-metal\n  dichalcogenides: We study valley-dependent spin transport theoretically in monolayer\ntransition-metal dichalcogenides in which a variety of spin and valley physics\nare expected because of spin-valley coupling. The results show that the spins\nare valley-selectively excited with appropriate carrier doping and valley\npolarized spin current (VPSC) is generated. The VPSC leads to the spin-current\nHall effect, transverse spin accumulation originating from the Berry curvature\nin momentum space. The results indicate that spin excitations with spin-valley\ncoupling lead to both valley and spin transport, which is promising for future\nlow-consumption nanodevice applications.",
        "positive": "Resonant plasmonic terahertz detection in graphene split-gate\n  field-effect transistors with lateral p-n junctions: We evaluate the proposed resonant terahertz (THz) detectors on the base of\nfield-effect transistors (FETs) with split gates, electrically induced lateral\np-n junctions, uniform graphene layer (GL) or perforated (in the p-n junction\ndepletion region) graphene layer (PGL) channel. The perforated depletion region\nforms an array of the nanoconstions or nanoribbons creating the barriers for\nthe holes and electrons. The operation of the GL-FET- and PGL-FET detectors is\nassociated with the rectification of the ac current across the lateral p-n\njunction enhanced by the excitation of bound plasmonic oscillations in in the\np- and n-sections of the channel. Using the developed device model, we find the\nGL-FET and PGL-FET-detectors characteristics. These detectors can exhibit very\nhigh voltage responsivity at the THz radiation frequencies close to the\nfrequencies of the plasmonic resonances. These frequencies can be effectively\nvoltage tuned. We show that in PL-FET-detectors the dominant mechanism of the\ncurrent rectification is due to the tunneling nonlinearity, whereas in\nPGL-FET-detector the current rectification is primarily associated with the\nthermionic processes. Due to much lower p-n junction conductance in the\nPGL-FET-detectors, their resonant response can be substantially more pronounced\nthan in the GL-FET-detectors corresponding to fairly high detector\nresponsivity."
    },
    {
        "anchor": "Topological Landau-Zener Bloch Oscillations in Photonic Floquet Lieb\n  Lattices: The Lieb Lattice exhibits intriguing properties that are of general interest\nin both the fundamental physics and practical applications. Here, we\ninvestigate the topological Landau-Zener Bloch oscillation in a photonic\nFloquet Lieb lattice, where the dimerized helical waveguides is constructed to\nrealize the synthetic spin-orbital interaction through the Floquet mechanism,\nrendering us to study the impacts of topological transition from trivial gaps\nto non-trivial ones. The compact localized states of flat bands supported by\nthe local symmetry of Lieb lattice will be associated with other bands by\ntopological invariants, Chern number, and involved into Landau-Zener transition\nduring Bloch oscillation. Importantly, the non-trivial geometrical phases after\ntopological transitions will be taken into account for constructive and\ndestructive interferences of wave functions. The numerical calculations of\ncontinuum photonic medium demonstrate reasonable agreements with theoretical\ntight-binding model. Our results provide an ongoing effort to realize designed\nquantum materials with tailored properties.",
        "positive": "Graphene on silicon nitride for optoelectromechanical micromembrane\n  resonators: Due to their exceptional mechanical and optical properties, dielectric\nsilicon nitride (SiN) micromembrane resonators have become the centerpiece of\nmany optomechanical experiments. Efficient capacitive coupling of the membrane\nto an electrical system would facilitate exciting hybrid optoelectromechanical\ndevices. However, capacitive coupling of such dielectric membranes is rather\nweak. Here we add a single layer of graphene on SiN micromembranes and compare\nelectromechanical coupling and mechanical properties to bare dielectric\nmembranes and to membranes metallized with an aluminium layer. The\nelectrostatic coupling of graphene coated membranes is found to be equal to a\nperfectly conductive membrane. Our results show that a single layer of graphene\nsubstantially enhances the electromechanical capacitive coupling without\nsignificantly adding mass, decreasing the superior mechanical quality factor or\naffecting the optical properties of SiN micromembrane resonators."
    },
    {
        "anchor": "Self-excited Oscillations of Charge-Spin Accumulation Due to\n  Single-electron Tunneling: We theoretically study electronic transport through a layer of quantum dots\nconnecting two metallic leads. By the inclusion of an inductor in series with\nthe junction, we show that steady electronic transport in such a system may be\nunstable with respect to temporal oscillations caused by an interplay between\nthe Coulomb blockade of tunneling and spin accumulation in the dots. When this\ninstability occurs, a new stable regime is reached, where the average spin and\ncharge in the dots oscillate periodically in time. The frequency of these\noscillations is typically of the order of 1GHz for realistic values of the\njunction parameters.",
        "positive": "Spin quadrupoletronics: moving spin anisotropy around: We show that spin anisotropy can be transferred to an isotropic system by\ntransport of spin quadrupole moment. We derive the quadrupole moment current\nand continuity equation and study a high-spin valve structure consisting of two\nferromagnets coupled to a quantum dot probing an impurity spin. The quadrupole\nback-action on their coupled spin results in spin torques and anisotropic spin\nrelaxation which do not follow from standard spin current considerations. We\ndemonstrate the detection of the impurity spin by charge transport and its\nmanipulation by electric fields."
    },
    {
        "anchor": "Statistics of the Coulomb blockade peak spacings of a silicon quantum\n  dot: We present an experimental study of the fluctuations of Coulomb blockade peak\npositions of a quantum dot. The dot is defined by patterning the\ntwo-dimensional electron gas of a silicon MOSFET structure using stacked gates.\nThis permits variation of the number of electrons on the quantum dot without\nsignificant shape distortion. The ratio of charging energy to single particle\nenergy is considerably larger than in comparable GaAs/AlGaAs quantum dots. The\nstatistical distribution of the conductance peak spacings in the Coulomb\nblockade regime was found to be unimodal and does not follow the Wigner\nsurmise. The fluctuations of the spacings are much larger than the typical\nsingle particle level spacing and thus clearly contradict the expectation of\nrandom matrix theory.",
        "positive": "Substrate dopant induced electronic inhomogeneity in epitaxial bilayer\n  graphene: Two-dimensional (2D) materials have become a new territory for exploring\nnovel properties and functionalities because of their superior tunability. The\nunprecedented tunability of 2D materials is also accompanied by many and\nequally great challenges, as they are susceptible to defects and disorders. The\npresence of defects and disorders induces the inhomogeneity of electronic\nstates, often making it difficult to directly probe the intrinsic properties of\nmaterials. Therefore, many efforts have been devoted to improve the electronic\nhomogeneity, for example, by reducing the density of defects and disorders in\nthe materials and at the interface. However, little attention is paid to the\ndisorders embedded in underlying substrates. Here we investigate how individual\ndopants in substrate interact with 2D materials and give rise to the\nelectron-hole puddles by low temperature scanning tunneling microscopy (STM)\nand spectroscopy (STS). Specifically, we take the epitaxial bilayer graphene\ngrown on nitrogen doped silicon carbide (SiC) substrates as a model system,\nwhich has played the essential roles in many applications and fundamental\nstudies. The nitrogen dopants inside SiC substrate were imaged over the\nepitaxial graphene by STM for the first time. The charged nitrogen dopants from\nthe substrate induce the electron-lack puddles in graphene with a diameter of\n~2 nm, via Coulomb interaction. The Fermi level with respect to the Dirac point\nis modulated by the puddles with an amplitude of ~40 meV, causing the\nelectronic inhomogeneity of epitaxial graphene. Our findings on this prototype\nmaterial are expected to facilitate the quality improvement of graphene and\nother 2D materials in general."
    },
    {
        "anchor": "Transform-limited single photons from a single quantum dot: A semiconductor quantum dot mimics a two-level atom. Performance as a single\nphoton source is limited by decoherence and dephasing of the optical\ntransition. Even with high quality material at low temperature, the optical\nlinewidths are a factor of two larger than the transform-limit. A major\ncontributor to the inhomogeneous linewdith is the nuclear spin noise. We show\nhere that the nuclear spin noise depends on optical excitation, increasing\n(decreasing) with increasing resonant laser power for the neutral (charged)\nexciton. Based on this observation, we discover regimes where we demonstrate\ntransform-limited linewidths on both neutral and charged excitons even when the\nmeasurement is performed very slowly.",
        "positive": "Quantum Monte Carlo simulation of topological phase transitions: We study the electron-electron interaction effects on topological phase\ntransitions by the ab-initio quantum Monte Carlo simulation. We analyze\ntwo-dimensional class A topological insulators and three-dimensional Weyl\nsemimetals with the long-range Coulomb interaction. The direct computation of\nthe Chern number shows the electron-electron interaction modifies or\nextinguishes topological phase transitions."
    },
    {
        "anchor": "Designer curved-space geometry for relativistic fermions in Weyl\n  metamaterials: Weyl semimetals are recently discovered materials supporting emergent\nrelativistic fermions in the vicinity of band-crossing points known as Weyl\nnodes. The positions of the nodes and the low-energy spectrum depend\nsensitively on the time-reversal (TR) and inversion (I) symmetry breaking in\nthe system. We introduce the concept of Weyl metamaterials where the particles\nexperience a 3d curved geometry and gauge fields emerging from smooth spatially\nvarying TR and I breaking fields. The Weyl metamaterials can be fabricated from\nsemimetal or insulator parent states where the geometry can be tuned, for\nexample, through inhomogeneous magnetization. We derive an explicit connection\nbetween the effective geometry and the local symmetry-breaking configuration.\nThis result opens the door for a systematic study of 3d designer geometries and\ngauge fields for relativistic carriers. The Weyl metamaterials provide a route\nto novel electronic devices as highlighted by a remarkable 3d electron lens\neffect.",
        "positive": "Topological waveguide based on metamaterials of magnetic solitons: We theoretically investigate coupled gyration modes of magnetic solitons\nwhose distances to the nearest neighbors are staggered. In a one-dimensional\nbipartite lattice, analogous to the Su-Schrieffer-Heeger model, there is a\nmid-gap gyration mode bounded at the domain wall connecting topologically\ndistinct two phases. As a technological application, we show that a\none-dimensional domain-wall string in a two-dimensional soliton lattice can\nserve as a topological waveguide of magnetic excitations, which offers\nfunctionalities of a signal localization and a selective propagation of the\nfrequency modes. Our result offers an alternative way to control of the\nmagnetic excitation modes by using a magnetic metamaterial for future\nspintronic devices."
    },
    {
        "anchor": "Coulomb Blockade with Dispersive Interfaces: What quantity controls the Coulomb blockade oscillations if the dot--lead\nconductance is essentially frequency--dependent ? We argue that it is the ac\ndissipative conductance at the frequency given by the effective charging\nenergy. The latter may be very different from the bare charging energy due to\nthe interface--induced capacitance (or inductance). These observations are\nsupported by a number of examples, considered from the weak and strong coupling\n(perturbation theory vs. instanton calculus) perspectives.",
        "positive": "Entanglement witnessing and quantum cryptography with non-ideal\n  ferromagnetic detectors: We investigate theoretically the use of non-ideal ferromagnetic contacts as a\nmean to detect quantum entanglement of electron spins in transport experiments.\nWe use a designated entanglement witness and find a minimal spin polarization\nof $\\eta > 1/\\sqrt{3} \\approx 58 %$ required to demonstrate spin entanglement.\nThis is significantly less stringent than the ubiquitous tests of Bell's\ninequality with $\\eta > 1/\\sqrt[4]{2}\\approx 84%$. In addition, we discuss the\nimpact of decoherence and noise on entanglement detection and apply the\npresented framework to a simple quantum cryptography protocol. Our results are\ndirectly applicable to a large variety of experiments."
    },
    {
        "anchor": "Theory of the Three Dimensional Quantum Hall Effect in Graphite: We predict the existence of a three dimensional quantum Hall effect plateau\nin a graphite crystal subject to a magnetic field. The plateau has a Hall\nconductivity quantized at $\\frac{4e^2}{\\hbar} \\frac{1}{c_0} $ with $c_0$ the\nc-axis lattice constant. We analyze the three-dimensional Hofstadter problem of\na realistic tight-binding Hamiltonian for graphite, find the gaps in the\nspectrum, and estimate the critical value of the magnetic field above which the\nHall plateau appears. When the Fermi level is in the bulk Landau gap, Hall\ntransport occurs through the appearance of chiral surface states. We estimate\nthe magnetic field necessary for the appearance of the three dimensional\nquantum Hall Effect to be $15.4 $T for electron carriers and $7.0 $T for hole\ncarriers.",
        "positive": "A U-shaped bilayer graphene channel transistor with a very high Ion/Ioff\n  ratio: A novel graphene transistor architecture is reported. The transistor has a\nU-shape geometry and was fabricated using a gallium focused ion beam (FIB). The\nchannel conductance was tuned with a back gate. The Ion/Ioff ratio exceeded\n10^5."
    },
    {
        "anchor": "Theory of edge states based on the hermiticity of tight-binding\n  Hamiltonian operators: We develop a theory of edge states based on the Hermiticity of Hamiltonian\noperators for tight-binding models defined on lattices with boundaries. We\ndescribe Hamiltonians using shift operators which serve as differential\noperators in continuum theories. It turns out that such Hamiltonian operators\nare not necessarily Hermitian on lattices with boundaries, which is due to the\nboundary terms associated with the summation by parts. The Hermiticity of\nHamiltonian operators leads to natural boundary conditions, and for models with\nnearest-neighbor (NN) hoppings only, there are reference states that satisfy\nthe Hermiticity and boundary conditions simultaneously. Based on such reference\nstates, we develop a Bloch-type theory for edge states of NN models on a\nhalf-plane. This enables us to extract Hamiltonians describing edge-states at\none end, which are separated from the bulk contributions. It follows that we\ncan describe edge states at the left and right ends separately by distinct\nHamiltonians for systems of cylindrical geometry. We show various examples of\nsuch edge state Hamiltonians (ESHs), including Hofstadter model, graphene\nmodel, and higher-order topological insulators (HOTIs).",
        "positive": "Giant Magneto-refractive Effect in Second Harmonic Generation from\n  Plasmonic Antennas in the Mid-infrared: Metallic nanostructures exhibit strong nonlinear-optical response at surface\nplasmon resonances, where the light-matter coupling efficiency is enhanced. An\nactive modulation of this response can be realized by means of an external\nmagnetic field. Here we utilize a nonlinear magneto-refractive effect in\nspintronic multilayer antennas to achieve a resonant 20\\% modulation in second\nharmonic generation (SHG) in the mid-infrared. We discuss mechanisms of this\nmodulation and show that it cannot be explained by an unequal enhancement of\nthe electromagnetic field in the two spin states of the multilayer. Instead, we\npropose a novel contribution to the nonlinear susceptibility, which relies on\nthe spin-dependent electron mean free path in metals. In contrast to\nmagneto-optics in ferromagnets, our approach results in no shift of the\nresonance and thus ensures that the largest SHG and its strongest modulation\nare simultaneously observed."
    },
    {
        "anchor": "Generation of femtosecond spin-polarized current pulses at Fe/MgO\n  interface by quasi-static voltage: The generation of short spin-current pulses is essential for fast spintronic\ndevices. So far, spin current pulses are generated by femtosecond laser pulses\nwhich drive spins from a ferromagnetic metal layer. However, the need for\nminiaturization, simplicity and energy efficiency favour electric-field control\nof spintronic devices over optic or thermal control. Here, we combine ab initio\ncalculations of electronic density of states at MgO/Fe interface with\ncontinuous model for charge transport to investigate the dynamics of the\nspin-dependent potential. We demonstrate that the voltage-driven instability of\nthe electronic band structure due to the electronic resonant states at the\nFe/MgO interface results in the generation of the femtosecond spin-polarized\ncurrent pulse with the spin polarization up to P=700% that propagates from the\ninterface to the bulk. The dynamics of the current pulses driven by the Stoner\ninstability depends neither on the dielectric relaxation time nor on the\ndetails of how the instability is achieved by changing the voltage, i.e. as\nlong as the voltage changes are slow (quasi-static) with respect to the time\ndetermined by the spin diffusion constant, being of the order of fs.The\npresence of the instability may be detected by transport or magnetic\nmeasurements.",
        "positive": "Superconducting proximity effect in a transparent van der Waals\n  superconductor-metal junction: We report on Andreev reflections at clean NbSe2-bilayer graphene junctions.\nThe high transparency of the junction, which manifests as a large conductance\nenhancement of up to 1.8, enables us to see clear evidence of a\nproximity-induced superconducting gap in bilayer graphene and two Andreev\nreflections through a vertical NbSe2-graphene and a lateral graphene-graphene\njunction respectively. Quantum transport simulations capture the complexity of\nthe experimental data and illuminate the impact of various microscopic\nparameters on the transmission of the junction. Our work establishes the\npractice and understanding of an all-van-der-Waals, high-performance\nsuperconducting junction. The realization of a highly transparent proximized\ngraphene-graphene junction opens up possibilities to engineer emergent quantum\nphenomena."
    },
    {
        "anchor": "Calculating the transport properties of magnetic materials from\n  first-principles including thermal and alloy disorder, non-collinearity and\n  spin-orbit coupling: A density functional theory based two-terminal scattering formalism that\nincludes spin-orbit coupling and spin non-collinearity is described. An\nimplementation using tight-binding muffin-tin orbitals combined with extensive\nuse of sparse matrix techniques allows a wide variety of inhomogeneous\nstructures to be flexibly modelled with various types of disorder including\ntemperature induced lattice and spin disorder. The methodology is illustrated\nwith calculations of the temperature dependent resistivity and magnetization\ndamping for the important substitutional disordered magnetic alloy Permalloy\n(Py), Ni$_{80}$Fe$_{20}$. Comparison of calculated results with recent\nexperimental measurements of the damping (including its temperature dependence)\nindicates that the scattering approach captures the most important\ncontributions to this important property.",
        "positive": "High-yield fabrication of entangled photon emitters for hybrid quantum\n  networking using high-temperature droplet epitaxy: Several semiconductor quantum dot techniques have been investigated for the\ngeneration of entangled photon pairs. Among the other techniques, droplet\nepitaxy enables the control of the shape, size, density, and emission\nwavelength of the quantum emitters. However, the fraction of the\nentanglement-ready quantum dots that can be fabricated with this method is\nstill limited to around 5%, and matching the energy of the entangled photons to\natomic transitions (a promising route towards quantum networking) remains an\noutstanding challenge.\n  Here, we overcome these obstacles by introducing a modified approach to\ndroplet epitaxy on a high symmetry (111)A substrate, where the fundamental\ncrystallization step is performed at a significantly higher temperature as\ncompared to previous reports. Our method drastically improves the yield of\nentanglement-ready photon sources near the emission wavelength of interest,\nwhich can be as high as 95% due to the low values of fine structure splitting\nand radiative lifetime, together with the reduced exciton dephasing offered by\nthe choice of GaAs/AlGaAs materials. The quantum dots are designed to emit in\nthe operating spectral region of Rb-based slow-light media, providing a viable\ntechnology for quantum repeater stations."
    },
    {
        "anchor": "2D superconductivity and vortex dynamics in 1T-MoS2: Two-dimensional (2D) superconductivity is a fascinating phenomenon packed\nwith rich physics and wide technological application. The vortices and their\ndynamics arising from classical and quantum fluctuations give rise to\nBerezinskii-Kosterlitz-Thouless (BKT) transition and 2D Bose metallic phase\nboth of which are of fundamental interest. In 2D, observation of\nsuperconductivity and the associated phenomena are sensitive to material\ndisorders. Highly crystalline and inherently 2D van der Waals (vW) systems with\ncarrier concentration and conductivity approaching metallic regime have been a\npotential platform. The metallic 1T phase of MoS2, a widely explored vW\nmaterial system controllably, engineered from the semiconducting 2H phase, is a\ntangible choice. Here, we report the observation of 2D superconductivity\naccompanied by BKT transition and Bose metallic state in a few-layer 1T-MoS2.\nStructural characterization shows excellent crystallinity over extended lateral\ndimension. The electrical characterization confirms the metallic nature down to\n4 K and a transition to a superconducting state below 1.2 K with a Tc ~ 920 mK.\nThe 2D nature of the superconducting state is confirmed from the\nmagneto-transport anisotropy against field orientations and the presence of BKT\ntransition. In addition, our sample showcases a manifold increase in the\nparallel upper-critical-field above the Pauli limit. The inherent\ntwo-dimensionality and possibility of scalably engineering semiconducting,\nmetallic and superconducting phases makes MoS2 a potential candidate for\nhosting monolithic all-two-dimensional hybrid quantum devices.",
        "positive": "Mono-stability of sharp tips interacting with surface hydration layers: It is generally thought that capillary interactions in nanoscale contacts\ngive rise to unwanted behaviour due to high adhesion. We show that this is not\nthe case for sufficiently small contacts in ambient conditions. High resolution\nambient atomic force microscopy AFM requires tip-sharpness, proximity and small\nforces, but the cantilever dynamics might not allow these three conditions to\nbe met simultaneously. Hitherto, accepted dogma is that small drive amplitudes\nlead to either tip trapping or L mode (attractive) imaging, where proximity is\ninhibited. Here we show that the hydration layer might be responsible for\nallowing the AFM tip to be brought stably within angstroms of the surface using\na small amplitude small set-point (SASS) mode. This phenomenon enhances\nresolution and stability while dramatically reducing tip wear."
    },
    {
        "anchor": "Electrically Tunable Magnetism in Magnetic Topological Insulators: The external controllability of the magnetic properties in topological\ninsulators would be important both for fundamental and practical interests.\nHere we predict the electric-field control of ferromagnetism in a thin film of\ninsulating magnetic topological insulators. The decrease of band inversion by\nthe application of electric fields results in a reduction of magnetic\nsusceptibility, and hence in the modification of magnetism. Remarkably, the\nelectric field could even induce the magnetic quantum phase transition from\nferromagnetism to paramagnetism. We further propose a topological transistor\ndevice in which the dissipationless charge transport of chiral edge states is\ncontrolled by an electric field. In particular, the field-controlled\nferromagnetism in magnetic topological insulator can be used for voltage based\nwriting of magnetic random access memories in magnetic tunnel junctions. The\nsimultaneous electrical control of magnetic order and chiral edge transport in\nsuch devices may lead to electronic and spintronic applications for topological\ninsulators.",
        "positive": "Phonon-induced decoherence of a charge quadrupole qubit: Many quantum dot qubits operate in regimes where the energy splittings\nbetween qubit states are large and phonons can be the dominant source of\ndecoherence. The recently proposed charge quadrupole qubit, based on one\nelectron in a triple quantum dot, employs a highly symmetric charge\ndistribution to suppress the influence of charge noise. To study the effects of\nphonons on the charge quadrupole qubit, we consider Larmor and Ramsey pulse\nsequences to identify favorable operating parameters. We show that it is\npossible to implement typical gates with $>99.99\\%$ fidelity in the presence of\nphonons and charge noise."
    },
    {
        "anchor": "Excitons and trions with negative effective masses in two-dimensional\n  semiconductors: We study theoretically fundamental Coulomb-correlated complexes: neutral and\ncharged excitons, also known as trions, in transition metal dichalogenides\nmonolayers. We focus on the situation where one of the electrons occupies\nexcited, high-lying, conduction band characterized by a negative effective\nmass. We develop the theory of such high-lying excitons and trions with\nnegative effective mass and demonstrate the key role of the non-parabolicity of\nthe high-lying conduction band dispersion in formation of the bound exciton and\ntrion states. We present simple, accurate and physically justified trial\nwavefunctions for calculating the binding energies of Coulomb-bound complexes\nand compare the results of variational calculations with those of a fully\nnumerical approach. Within the developed model we discuss recent experimental\nresults on observation of high-lying negative effective mass trions [K.-Q. Lin\net al., Nat. Commun. 13, 6980 (2022)].",
        "positive": "Lattice dynamics, phonon chirality and spin-phonon coupling in 2D\n  itinerant ferromagnet Fe3GeTe2: Fe3GeTe2 has emerged as one of the most fascinating van der Waals crystals\ndue to its two-dimensional (2D) itinerant ferromagnetism, topological nodal\nlines and Kondo lattice behavior. However, lattice dynamics, chirality of\nphonons and spin-phonon coupling in this material, which set the foundation for\nthese exotic phenomena, have remained unexplored. Here we report the first\nexperimental investigation of the phonons and mutual interactions between spin\nand lattice degrees of freedom in few-layer Fe3GeTe2. Our results elucidate\nthree prominent Raman modes at room temperature: two A1g({\\Gamma}) and one\nE2g({\\Gamma}) phonons. The doubly degenerate E2g({\\Gamma}) mode reverses the\nhelicity of incident photon, indicating the pseudo-angular momentum and\nchirality. Through analysis of temperature-dependent phonon energies and\nlifetimes, which strongly diverge from the anharmonic model below Curie\ntemperature, we determine the spin-phonon coupling in Fe3GeTe2. Such\ninteraction between lattice oscillations and spin significantly enhances the\nRaman susceptibility, allowing us to observe two additional Raman modes at the\ncryogenic temperature range. In addition, we reveal laser radiation induced\ndegradation of Fe3GeTe2 in ambient conditions and the corresponding Raman\nfingerprint. Our results provide the first experimental analysis of phonons in\nthis novel 2D itinerant ferromagnet and their applicability for further\nfundamental studies and application development."
    },
    {
        "anchor": "Electronic transport through a parallel--coupled triple quantum dot\n  molecule: Fano resonances and bound states in the continuum: The electronic transport through a triple quantum dot molecule attached in\nparallel to leads in presence of a magnetic flux is studied. Analytical\nexpressions of the linear conductance and density of states for the molecule in\nequilibrium at zero temperature are obtained. As a consequence of quantum\ninterference, the conductance exhibits in general a Breit--Wigner and two Fano\nresonances, the positions and widths of which are controlled by the magnetic\nfield. Every two flux quanta, there is an inversion of roles of the bonding and\nantibonding states. For particular values of the magnetic flux and dot-lead\ncouplings, one or even both Fano resonances collapse and bound states in the\ncontinuum (BIC's) are formed. The line broadenings of the molecular states are\nexamined as a function of the Aharonov--Bohm phase around the condition for the\nformation of BIC's, finding resonances extremely narrow and robust against\nvariations of the magnetic field.",
        "positive": "Spin waves in periodic antidot waveguide of complex base: We consider the planar magnonic waveguide with a periodic sequence of\nantidots forming zig-zag pattern, where two neighboring antidots are shifted\ntowards the opposite edges of the waveguide. This system has a complex base\nwith two antidots in one unit cell. The Brillouin zone is here two-times\nnarrower than the Brillouin zone for the waveguide without displacement of\nantidots. We have shown that for dispersion relation folded into narrower\nBrillouin zone, new frequency gap can be opened and their width can be\ncontrolled by the shift of the antidots. We found that, the different strength\nof spin wave pinning at the edges of the periodic waveguide (and their\nantidots)determines the dependence of the width of gap on the shift of\nantidots. For the systems with completely free or ideally pinned magnetization,\nthese dependencies are qualitatively different. We have found an optimum shift\nof antidot for maximzing the width of the gap for the system with pinned\nmagnetization. More interestingly, we notice that for this kind of geometry of\nthe structure, majority of the modes are doubly degenerate at the edge of\nBrillouin zone and have a finite group velocity at the very close vicinity of\nthe edge of Brillouin zone, for larger values of antidot shift. This empowers\nus to design magnonic waveguide to steer the spin waves."
    },
    {
        "anchor": "Scanning SQUID-on-tip microscope in a top-loading cryogen-free dilution\n  refrigerator: The scanning superconducting quantum interference device (SQUID) fabricated\non the tip of a sharp quartz pipette (SQUID-on-tip) has emerged as a versatile\ntool for nanoscale imaging of magnetic, thermal, and transport properties of\nmicroscopic devices of quantum materials. We present the design and performance\nof a scanning SQUID-on-tip microscope in a top-loading probe of a cryogen-free\ndilution refrigerator. The microscope is enclosed in a custom-made vacuum-tight\ncell mounted at the bottom of the probe and is suspended by springs to suppress\nvibrations caused by the pulse tube cryocooler. Two capillaries allow in-situ\ncontrol of helium exchange gas pressure in the cell that is required for\nthermal imaging. A nanoscale heater is used to create local temperature\ngradients in the sample, which enables quantitative characterization of the\nrelative vibrations between the tip and the sample. The spectrum of the\nvibrations shows distinct resonant peaks with maximal power density of about 27\nnm/Hz$^{1/2}$ in the in-plane direction. The performance of the SQUID-on-tip\nmicroscope is demonstrated by magnetic imaging of the MnBi$_2$Te$_4$ magnetic\ntopological insulator, magnetization and current distribution imaging in a\nSrRuO$_3$ ferromagnetic oxide thin film, and by thermal imaging of dissipation\nin graphene.",
        "positive": "Ab-initio analysis of superstructures revealed by STM on bilayer\n  graphene: In this work we performed density functional theory calculations for a\ntwisted bilayer graphene (BLG). Several conmensurable rotation angles were\nanalyzed and for each one a constant height mode STM image was obtained. These\nSTM images, calculated under the Tersoff-Hamman theory, reproduce the main\nfeatures experimentally observed, paticularly superstructures and giant\ncorrugations. In this way we confirm that STM characterization of twisted BLG\ncan produce superstructures whose tunneling current intensity maxima occur over\nregions with $AA$ stacking. Additionally we give new evidence in favour of an\nelectronic origin for the superstructures instead another physical grounds."
    },
    {
        "anchor": "2D clathrate graphene in minimum egg-tray-shape: An \\textit{ab initio}\n  study: The thriving area of synthetic carbon allotropes witnesses theoretic\nproposals and experimental syntheses of many new two-dimensional ultrathin\nstructures, which are often achieved by careful arrangement of non-hexagon\n$\\mathrm{sp^2}$ defects in graphene. Here, we introduce pyramid $\\mathrm{sp^3}$\nhybridization into $\\mathrm{sp^2}$ network and propose a new carbon polymorph\nwith clathrate pattern and with minimum egg-tray shape (termed as clathrate\ngraphene). Eight symmetrically equivalent $\\mathrm{sp^2}$ carbon atoms and two\nsymmetrically equivalent $\\mathrm{sp^2}$ carbon atoms in its tetragonal\nprimitive unit cell form two perpendicularly oriented rectangles and four\nbridging hexagons. Though deformed bond lengths and bond angles, the planar\ngeometry of both tetrarings and hexagons are retained. High percentage and\nsmall deformation of hexagons make this metastable\n$\\mathrm{sp^2}$-$\\mathrm{sp^3}$ allotrope comparable with pure $\\mathrm{sp^2}$\n$T$-graphene and penta-graphene in energetics. Exhaustive \\textit{ab initio}\ncalculations confirm its dynamical and elastic stabilities, reveal its\nsemiconducting nature with an indirect band gap of 0.90 eV for unstressed\nsample, and suggest a giant strain tuning effect which endows versatile\nelectronic properties ranging from metallic to semiconducting. Furthermore, we\nobserve multiple von Hove singularities near the Fermi energy.These salient\nproperties may imply potential nanoelectronic applications. These findings help\nunderstand structure-property relationship for two-dimensional carbon\nallotropes, and help search new carbon polymorphs.",
        "positive": "Junction-Less Monolayer MoS2 FETs: This paper introduces monolayer molybdenum disulfide (MoS2) based\njunction-less (JL) field-effect transistor (FET) and evaluates its performance\nat the smallest foreseeable (5.9 nm) transistor channel length as per the\nInternational Technology Roadmap for Semiconductors (ITRS), by employing\nrigorous quantum transport simulations. By comparing with MoS2 based\nconventional FETs, it is found that the JL structure naturally lends MoS2 FETs\nwith superior device electrostatics, and higher ON-current for both\nhigh-performance and low-standby-power applications, especially at high\nimpurity doping densities. Along with the advantages of the MoS2 JL-FETs, the\neffects of impurity scattering induced carrier mobility degradation of JL-FETs\nis also highlighted as a key technological issue to be addressed for exploiting\ntheir unique features."
    },
    {
        "anchor": "Dynamical control over the confinement of spatially indirect excitons in\n  electrostatic traps of GaAs coupled quantum wells: We study spatially indirect excitons confined in a 10 $\\mu$m wide\nelectrostatic trap of a GaAs double quantum well. We introduce a technique to\ncontrol the amplitude of the electric field interacting with the excitons\nelectric dipole, with nanosecond precision. Our approach relies on electronic\nwaveforms corrected for the distorsions occurring at highest frequencies so\nthat impedance matching is not necessary. Thus, we manipulate the confinement\nof cold gases without inducing sizeable perturbations down to sub-Kelvin bath\ntemperatures.",
        "positive": "Saddle point singularity and topological phase diagram in a tunable\n  topological crystalline insulator (TCI): A topological crystalline insulator (TCI) is a new phase of topological\nmatter, which is predicted to exhibit distinct topological quantum phenomena,\nsince space group symmetries replace the role of time-reversal symmetry in the\nmuch-studied Z$_2$ topological insulators. Utilizing high-resolution\nangle-resolved photoemission spectroscopy (ARPES), we reveal the momentum space\nnature of interconnectivity of the Fermi surface pockets leading to a saddle\npoint singularity within the topological surface state alone in the TCI\nPb$_{0.7}$Sn$_{0.3}$Se. Moreover, we show that the measured momentum-integrated\ndensity of states exhibits pronounced peaks at the saddle point energies,\ndemonstrating the van Hove singularities (VHSs) in the topological surface\nstates, whose surface chemical potential, as we show, can be tuned via surface\nchemical gating, providing access to the topological correlated physics on the\nsurface. Our experimental data reveal a delicate relationship among lattice\nconstant, band gap and spin-orbit coupling strength associated with the\ntopological phase transition in Pb$_{1-x}$Sn$_{x}$Se. Furthermore, we explore\nthe robustness of the TCI phase with VHS in Pb$_{1-x}$Sn$_{x}$Se, which shows a\nvariety of distinct topological phase transitions driven by either thermal\ninstability or broken crystalline symmetry, and thus revealing a rich\ntopological phase diagram connectivity in Pb$_{1-x}$Sn$_{x}$Se for the first\ntime."
    },
    {
        "anchor": "Oscillatory Edge Modes in Two Dimensional Spin-Torque Oscillator Arrays: Spin torque oscillators (STOs) are dissipative magnetic systems that provide\na natural platform for exploring non-Hermitian phenomena. We theoretically\nstudy a two-dimensional (2d) array of STOs and show that its dynamics can be\nmapped to a 2d, non-Hermitian Su-Schrieffer-Heeger (SSH) model. We calculate\nthe energy spectrum and identify the one-dimensional (1d) edge states of our\nmodel, corresponding to auto-oscillation of STOs on the boundary of the system\nwhile the bulk oscillators do not activate. We show that tuning the Gilbert\ndamping, injected spin current, and coupling between STOs allows for exploring\nthe edge state properties under different parameter regimes. Furthermore, this\nsystem admits 1d edge states with non-uniform probability density, and we\nexplore their properties in systems of different sizes. Additional symmetry\nanalysis indicates that these states are not topologically protected but are\nnevertheless confined to the edge of the system, as the bulk is protected by\nPT-symmetry. These results indicate that 2d arrays of STOs may be useful to\nexplore novel edge state behavior in dissipative systems.",
        "positive": "Mechanisms of jump to contact and conductance plateau formation in\n  copper atomic junctions in vacuum and aqueous environments: The interplay between groups of water molecules and single-atom contacts, as\nreflected in the electrical conductances and mechanical forces of copper atomic\njunctions, is explored by means of first-principles theory and semi-empirical\ncalculations. We study the influence of the atomic geometries of copper\nelectrodes with pyramidal and non-crystalline structures in the presence and\nabsence of water on the conductance profiles as the electrodes approach each\nother. It is shown that the atomic arrangements of nano-contacts have crucial\neffects on the formation of plateaus and the conductance values. Groups of\nhydrogen bonded water molecules bridge the junction electrodes before a direct\nCu-Cu contact between the electrodes is made. However, the bridging of the two\ncopper electrodes by a single H$_{2}$O molecule only occurs in the junctions\nwith pyramidal electrodes. Our findings reveal that the presence of H$_{2}$O\nmolecules modifies strongly the conductance profile of these junctions. In the\nabsence of water molecules, the pyramidal junctions exhibit continuous\ntransitions between integer conductance plateaus, while in the presence of\nH$_{2}$O molecules, these junctions show abrupt jump to contact behavior and no\nwell-defined conductance plateaus. By contrast, in the absence of H$_{2}$O\nmolecules, the non-crystalline junctions display jump to contact behavior and\nno well-defined plateaus, while in the presence of H$_{2}$O molecules they\nexhibit a jump to contact and abrupt transitions between fractional and integer\nplateaus."
    },
    {
        "anchor": "Local field enhancement at the core of cylindrical nanoinclusions\n  embedded in a linear dielectric host matrix: In this paper we have discussed theoretical concepts and presented numerical\nresults of local field enhancement at the core of different assemblages of\nmetal/dielectric cylindrical nanoinclusions embedded in a linear dielectric\nhost matrix. The obtained results show that for a composite with metal coated\ninclusions there exist two peak values of the enhancement factor at two\ndifferent resonant frequencies. The existence of the second maxima becomes more\nimportant for a larger volume fraction of the metal part of the inclusion. For\ndielectric coated metal core inclusions and pure metal inclusions there is only\none resonant frequency and one peak value of the enhancement factor. The\nenhancement of an electromagnetic wave is promising for the existence of\nnonlinear optical phenomena such as optical bistability which is important in\noptical communication and in optical computing such as optical switch and\nmemory elements.",
        "positive": "Low temperature dissipation scenarios in palladium nano-mechanical\n  resonators: We study dissipation in Pd nano-mechanical resonators at low temperatures in\nthe linear response regime. Metallic resonators have shown characteristic\nfeatures of dissipation due to tunneling two level systems (TLS). This system\noffers a unique tunability of the dissipation scenario by adsorbing hydrogen\n($H_2$) which induces a compressive stress. The intrinsic stress is expected to\nalter TLS behaviour. We find a sub-linear power law $\\sim T^{0.4}$ in\ndissipation. As seen in TLS dissipation scenarios we find a logarithmic\nincrease of frequency characteristic from the lowest temperatures till a\ncharacteristic temperature $T_{co}$ is reached. In samples without $H_2$ the\n$T_{co} \\sim 1K$ whereas with $H_2$ it is clearly reduced to $\\sim 700 mK$.\nBased on standard TLS phenomena we attribute this to enhanced phonon-TLS\ncoupling in samples with compressive strain. We also find with $H_2$ there is a\nsaturation in low temperature dissipation which may possibly be due to\nsuper-radiant interaction between TLS and phonons. We discuss the data in the\nscope of TLS phenomena and similar data for other systems."
    },
    {
        "anchor": "Inertial and topological effects on a 2D electron gas: In this work, we study how the combination of rotation and a topological\ndefect can influence the energy spectrum of a two dimensional electron gas in a\nstrong perpendicular magnetic field. A deviation from the linear behavior of\nthe energy as a function of magnetic field, caused by a tripartite term of the\nHamiltonian, involving magnetic field, the topological charge of the defect and\nthe rotation frequency, leads to novel features which include a range of\nmagnetic field without corresponding Landau levels and changes in the Hall\nquantization steps.",
        "positive": "Quantum computation with quasiparticles of the Fractional Quantum Hall\n  Effect: We propose an approach that enables implementation of anyonic quantum\ncomputation in systems of antidots in the two-dimensional electron liquid in\nthe FQHE regime. The approach is based on the adiabatic transfer of FQHE\nquasiparticles in the antidot systems, and uses their fractional statistics to\nperform quantum logic. Advantages of our scheme over other semiconductor-based\nproposals of quantum computation include the energy gap in the FQHE liquid that\nsuppresses decoherence, and the topological nature of quasiparticle statistics\nthat makes it possible to entangle two quasiparticles without their direct\ndynamic interaction."
    },
    {
        "anchor": "Thermo-electric transport properties of Floquet multi-Weyl Semimetals: We discuss the circularly polarized light (of amplitude $A_0$ and frequency\n$\\omega$) driven thermo-electric transport properties of type-I and type-II\nmulti-Weyl semimetals (mWSMs) in the high frequency limit. Considering the low\nenergy model, we employ the Floquet-Kubo formalism to compute the thermal Hall\nand Nernst conductivities for both types of mWSMs. We show that the anisotropic\nnature of the dispersion for arbitrary integer monopole charge $n>1$ plays an\nimportant role in determining the effective Fermi surface behavior;\ninterestingly, one can observe momentum dependent corrections in Floquet mWSMs\nin addition to momentum independent contribution as observed for Floquet single\nWSMs. Apart from the non-trivial tuning of the Weyl node position $\\pm Q \\to\n\\pm Q- A_0^{2n}/\\omega$, our study reveals that the momentum independent terms\nresult in leading order contribution in the conductivity tensor. This has the\nform of $n$ times the single WSMs results with effective chemical potential\n$\\mu \\to \\mu -A_0^{2n}/\\omega$. On the other hand, momentum dependent\ncorrections lead to sub-leading order terms which are algebraic function of\n$\\mu$ and are present for $n>1$. Remarkably, this analysis further allows us to\ndistinguish type-I mWSMs from their type-II counterparts. For type-II mWSMs, we\nfind that the transport coefficients for $n\\geq 2$ exhibit algebraic dependence\non the momentum cutoff in addition to the weak logarithmic dependence as\nnoticed for $n=1$ WSMs. We demonstrate the variation and qualitative\ndifferences of transport coefficients between type-I and type-II mWSM as a\nfunction of external driving parameter $\\omega$.",
        "positive": "Comparison between charge and spin transport in few layer graphene: Transport measurements on few layer graphene (FLG) are important as they\ninterpolate between the properties of single layer graphene (SLG) as a true\n2-dimensional material and the 3-dimensional bulk properties of graphite. In\nthis article we present 4-probe local charge transport and non-local spin valve\nand spin precession measurements on lateral spin field-effect transistors (FET)\non FLG. We study systematically the charge and spin transport properties\ndepending on the number of layers and the electrical back gating of the device.\nWe explain the charge transport measurements by taking the screening of\nscattering potentials into account and use the results to understand the spin\ndata. The measured samples are between 3 and 20 layers thick and we include in\nour analysis our earlier results of the measurements on SLG for comparison. In\nour room temperature spin transport measurements we manage to observe spin\nsignals over distances up to 10 u m and measure spin-relaxation times up to\ntau_s ~500 ps, about 4 times higher than in SLG. We calculate the density of\nstates (DOS) of FLG using a zone-folding scheme to determine the charge\ndiffusion coefficient D_C from the square resistance R_S. The resulting D_C and\nthe spin diffusion coefficient D_S show similar values and depend only weakly\non the number of layers and gate induced charge carriers. We discuss the\nimplications of this on the identification of the spin-relaxation mechanism."
    },
    {
        "anchor": "Boundary Conditions and Surface States Spectra in Topological Insulators: We study spectra of surface states in 2D topological insulators (TIs) based\non HgTe/(Hg,Cd)Te quantum wells and 3D Bi$_2$Se$_3$-type compounds by\nconstructing a class of feasible time-reversal invariant boundary conditions\n(BCs) for an effective ${\\bf k}{\\bf p}$-Hamiltonian and a tight-binding model\nof the topological insulators. The BCs contain some phenomenological parameters\nwhich implicitly depend on both bulk Hamiltonian parameters and crystal\npotential behavior near the crystal surface. Space symmetry reduces the number\nof the boundary parameters to four real parameters in the 2D case and three in\nthe 3D case. We found that the boundary parameters may strongly affect not only\nan energy spectrum but even the very existence of these states inside the bulk\ngap near the Brillouin zone center. Nevertheless, we reveal in frames of the\ntight-binding model that when surface states do not exist in the bulk gap in\nthe Brillouin zone center they cross the gap in other points of the Brillouin\nzone in agreement with the bulk-boundary correspondence.",
        "positive": "Cumulene Molecular Wire Conductance from First Principles: We present first principles calculations of current-voltage characteristics\n(IVC) and conductance of Au(111):S2-cumulene-S2:Au(111) molecular wire\njunctions with realistic contacts. The transport properties are calculated\nusing full self-consistent ab initio NEGF-DFT methods under external bias. The\nconductance of the cumulene wires shows oscillatory behavior depending on the\nnumber of carbon atoms (double bonds). Among all conjugated oligomers, we find\nthat cumulene wires with odd number of carbon atoms yield the highest\nconductance with metallic-like ballistic transport behavior. The reason is the\nhigh density of states in broad LUMO levels spanning the Fermi level of the\nelectrodes. The transmission spectrum and the conductance depend only weakly on\napplied bias, and the IVC is nearly linear over a bias region from +1 to -1 V.\nCumulene wires are therefore potential candidates for metallic connections in\nnanoelectronic applications."
    },
    {
        "anchor": "Anharmonicity of vibrational modes in fullerenes: We report a computational study of the anharmonicity of the vibrational modes\nof various individual fullerenes using the \"moments method\" [Y. Gao and M. Daw,\nModelling Simul. Mater. Sci. Eng. 23 045002 (2015)] with a Tersoff-style\npotential for carbon. We find that the frequencies of all vibrational modes\ndrop systematically with temperature and the sizes of the individual fullerenes\ndo not affect strongly the anharmonicity of the modes. Comparison is made with\navailable experiments.",
        "positive": "Scalable nanomechanical logic gate: Nanomechanical computers promise robust, low energy information processing.\nHowever, to date, electronics have generally been required to interconnect\ngates, while no scalable, purely nanomechanical approach to computing has been\nachieved. Here, we demonstrate a nanomechanical logic gate in a scalable\narchitecture. Our gate uses the bistability of a nonlinear mechanical resonator\nto define logical states. These states are efficiently coupled into and out of\nthe gate via nanomechanical waveguides, which provide the mechanical equivalent\nof electrical wires. Crucially, the input and output states share the same\nspatiotemporal characteristics, so that the output of one gate can serve as the\ninput for the next. Our architecture is CMOS compatible, while realistic\nminiaturisation could allow both gigahertz frequencies and an energy cost that\napproaches the fundamental Landauer limit. Together this presents a pathway\ntowards large-scale nanomechanical computers, as well as neuromorphic networks\nable to simulate computationally hard problems and interacting many-body\nsystems."
    },
    {
        "anchor": "Sub-nm wide electron channels protected by topology: Helical locking of spin and momentum and prohibited backscattering are the\nkey properties of topologically protected states. They are expected to enable\nnovel types of information processing such as spintronics by providing pure\nspin currents, or fault tolerant quantum computation by using the Majorana\nfermions at interfaces of topological states with superconductors. So far, the\nrequired helical conduction channels used to realize Majorana fermions are\ngenerated through application of an axial magnetic field to conventional\nsemiconductor nanowires. Avoiding the magnetic field enhances the possibilities\nfor circuit design significantly. Here, we show that sub-nanometer wide\nelectron channels with natural helicity are present at surface step-edges of\nthe recently discovered topological insulator Bi14Rh3I9. Scanning tunneling\nspectroscopy reveals the electron channels to be continuous in both energy and\nspace within a large band gap of 200 meV, thereby, evidencing its non-trivial\ntopology. The absence of these channels in the closely related, but\ntopologically trivial insulator Bi13Pt3I7 corroborates the channels'\ntopological nature. The backscatter-free electron channels are a direct\nconsequence of Bi14Rh3I9's structure, a stack of 2D topologically insulating,\ngraphene-like planes separated by trivial insulators. We demonstrate that the\nsurface of Bi14Rh3I9 can be engraved using an atomic force microscope, allowing\nnetworks of protected channels to be patterned with nm precision.",
        "positive": "Interlayer electric multipoles induced by in-plane field from quantum\n  geometric origins: We show that interlayer charge transfer in 2D materials can be driven by an\nin-plane electric field, giving rise to electrical multipole generation in\nlinear and second order of in-plane field. The linear and nonlinear effects\nhave quantum geometric origins in the Berry curvature and quantum metric\nrespectively, defined in extended parameter spaces characteristic of layered\nmaterials. We elucidate their symmetry characters, and demonstrate sizable\ndipole and quadrupole polarizations respectively in twisted bilayers and\ntrilayers of transition metal dichalcogenides. Furthermore, we show that the\neffect is strongly enhanced during the topological phase transition tuned by\ninterlayer translation. The effects point to a new electric control on layer\nquantum degree of freedom."
    },
    {
        "anchor": "Excitons, trions, and biexcitons in transition metal dichalcogenides:\n  magnetic field dependence: The influence of a perpendicular magnetic field on the binding energy and\nstructural properties of excitons, trions, and biexcitons in monolayers of\nsemiconducting transition metal dichalcogenides (TMDs) is investigated. The\nstochastic variational method (SVM) with a correlated Gaussian basis is used to\ncalculate the different properties of these few-particle systems. In addition,\nwe present a simplified variational approach which supports the SVM results for\nexcitons as a function of magnetic field. The exciton diamagnetic shift is\ncompared with recent experimental results and we extend this concept to trions\nand biexcitons. The effect of a local potential fluctuation, which we model by\na circular potential well, on the binding energy of trions and biexcitons is\ninvestigated and found to significantly increase the binding of those excitonic\ncomplexes.",
        "positive": "Magnetic field and contact resistance dependence of non-local charge\n  imbalance: Crossed Andreev reflection (CAR) in metallic nanostructures, a possible basis\nfor solid-state electron entangler devices, is usually investigated by\ndetecting non-local voltages in multi-terminal superconductor/normal metal\ndevices. This task is difficult because other subgap processes may mask the\neffects of CAR. One of these processes is the generation of charge imbalance\n(CI) and the diffusion of non-equilibrium quasi-particles in the\nsuperconductor. Here we demonstrate a characteristic dependence of non-local CI\non a magnetic field applied parallel to the superconducting wire, which can be\nunderstood by a generalization of the standard description of CI to non-local\nexperiments. These results can be used to distinguish CAR and CI and to extract\nCI relaxation times in superconducting nanostructures. In addition, we\ninvestigate the dependence of non-local CI on the resistance of the injector\nand detector contacts and demonstrate a quantitative agreement with a recent\ntheory using only material and junction characteristics extracted from separate\ndirect measurements."
    },
    {
        "anchor": "Selective and Fast Plasmon-Assisted Photo-Heating of Nanomagnets; A New\n  Route for Opto-Activated Nanomagnetic Logic and Artificial Spin Systems: Thermal relaxation of nanoscale magnetic islands, mimicking Ising macrospins,\nis indispensable for studies of geometrically frustrated artificial spin\nsystems and low-energy nanomagnetic computation. Currently-used heating schemes\nbased on contact to a thermal reservoir, however, lack the speed and spatial\nselectivity required for the implementation in technological applications.\nApplying a hybrid approach by combining a plasmonic nanoheater with a magnetic\nelement, in this work we establish the robust and reliable control of local\ntemperatures in nanomagnetic arrays by contactless optical means.\nPlasmon-assisted photo-heating allows for temperature increases of up to\nseveral hundred Kelvins, which lead to thermally-activated moment reversals and\na pronounced reduction of the magnetic coercive field. Furthermore, the\npolarization-dependent absorption cross section of elongated plasmonic elements\nenables sublattice-specific heating on sub-nanosecond time scales. Using\noptical degrees of freedom, i.e. focal position, polarization, power, and pulse\nlength, thermoplasmonic heating of nanomagnets offers itself for the use in\nflexible, fast, spatially-, and element-selective thermalization for functional\nmagnetic metamaterials.",
        "positive": "Mid-Infrared Detectors and Imagers Integrating All-Group IV Nanowires: Cost-effective mid-wave infrared (MWIR) optoelectronic devices are of utmost\nimportance to a plethora of applications such as night vision, thermal sensing,\nautonomous vehicles, free-space communication, and spectroscopy. To this end,\nleveraging the ubiquitous silicon-based processing has emerged as a powerful\nstrategy that can be accomplished through the use of group IV germanium-tin\n(GeSn) alloys. Indeed, due to their compatibility with silicon and their\ntunable bandgap energy covering the entire MWIR range, GeSn semiconductors are\nfrontrunner platforms for compact and scalable MWIR technologies. However, the\nGeSn large lattice parameter has been a major hurdle limiting the quality of\nGeSn epitaxy on silicon wafers. Herein, it is shown that sub-20 nm Ge nanowires\n(NWs) provide effective compliant substrates to grow Ge$_{1-x}$Sn$_{x}$ alloys\nwith a composition uniformity over several micrometers with a very limited\nbuild-up of the compressive strain. Ge/Ge$_{1-x}$Sn$_{x}$ core/shell NWs with\nSn content spanning the 6 to 18 at.$\\%$ range are demonstrated and integrated\nin photoconductive devices exhibiting a high signal-to-noise ratio at room\ntemperature and a tunable cutoff wavelength covering the 2.0 $\\mu$m to 3.9\n$\\mu$m range. Additionally, the processed NW-based detectors were used in\nuncooled imagers enabling the acquisition of high-quality images under both\nbroadband and laser illuminations without a lock-in technique."
    },
    {
        "anchor": "Luminescence Spectra of Quantum Dots in Microcavities. II. Fermions: We discuss the luminescence spectra of coupled light-matter systems realized\nwith semiconductor heterostructures in microcavities in the presence of a\ncontinuous, incoherent pumping, when the matter field is Fermionic. The linear\nregime--which has been the main topic of investigation both experimentally and\ntheoretically--converges to the case of coupling to a Bosonic material field,\nand has been amply discussed in the first part of this work. We address here\nthe nonlinear regime, and argue that, counter to intuition, it is better\nobserved at low pumping intensities. We support our discussion with particular\ncases representative of, and beyond, the experimental state of the art. We\nexplore the transition from the quantum to the classical regime, by decomposing\nthe total spectrum into individual transitions between the dressed states of\nthe light-matter coupling Hamiltonian, reducing the problem to the positions\nand broadenings of all possible transitions. As the system crosses to the\nclassical limit, rich multiplet structures mapping the quantized energy levels\nmelt and turn to cavity lasing and to an incoherent Mollow triplet in the\ndirect exciton emission for very good structure. Less ideal figures of merit\ncan still betray the quantum regime, with a proper balance of cavity versus\nelectronic pumping.",
        "positive": "Functional theories of thermoelectric phenomena: We review the progress that has been recently made in the application of\ntime-dependent density functional theory to thermoelectric phenomena. As the\nfield is very young, we emphasize open problems and fundamental issues. We\nbegin by introducing the formal structure of \\emph{thermal density functional\ntheory}, a density functional theory with two basic variables -- the density\nand the energy density -- and two conjugate fields -- the ordinary scalar\npotential and Luttinger's thermomechanical potential. The static version of\nthis theory is contrasted with the familiar finite-temperature density\nfunctional theory, in which only the density is a variable. We then proceed to\nconstructing the full time-dependent non equilibrium theory, including the\npractically important Kohn-Sham equations that go with it. The theory is shown\nto recover standard results of the Landauer theory for thermal transport in the\nsteady state, while showing greater flexibility by allowing a description of\nfast thermal response, temperature oscillations and related phenomena. Several\nresults are presented here for the first time, i.e., the proof of invertibility\nof the thermal response function in the linear regime, the full expression of\nthe thermal currents in the presence of Luttinger's thermomechanical potential,\nan explicit prescription for the evaluation of the Kohn-Sham potentials in the\nadiabatic local density approximation, a detailed discussion of the leading\ndissipative corrections to the adiabatic local density approximation and the\nthermal corrections to the resistivity that follow from it."
    },
    {
        "anchor": "Cotunneling-mediated transport through excited states in the Coulomb\n  blockade regime: We present finite bias transport measurements on a few-electron quantum dot.\nIn the Coulomb blockade regime, strong signatures of inelastic cotunneling\noccur which can directly be assigned to excited states observed in the\nnon-blockaded regime. In addition, we observe structures related to sequential\ntunneling through the dot, occuring after it has been excited by an inelastic\ncotunneling process. We explain our findings using transport calculations\nwithin the real-time Green's function approach, including diagrams up to fourth\norder in the tunneling matrix elements.",
        "positive": "Topological antiferromagnetic spintronics: Part of a collection of\n  reviews on antiferromagnetic spintronics: The recent demonstrations of electrical manipulation and detection of\nantiferromagnetic spins have opened up a chapter in the spintronics story. In\nthis article, we review the emerging research field that is exploring synergies\nbetween antiferromagnetic spintronics and topological structures in real and\nmomentum space. Active topics include proposals to realize Majorana fermions in\nan antiferromagnetic topological superconductors, to control topological\nprotection of Dirac points by manipulating antiferromagnetic order parameters,\nand to exploit the anomalous and topological Hall effects of zero net moment\nantiferromagnets. We explain the basic physics concepts behind these proposals,\nand discuss potential applications of topological antiferromagnetic\nspintronics."
    },
    {
        "anchor": "Noise-resistant quantum memory enabled by Hamiltonian engineering: Nuclear spins in quantum dots are promising candidates for fast and scalable\nquantum memory. By utilizing the hyperfine interaction between the central\nelectron and its surrounding nuclei, quantum information can be transferred to\nthe collective state of the nuclei and be stored for a long time. However,\nnuclear spin fluctuations in a partially polarized nuclear bath deteriorate the\nquantum memory fidelity. Here we introduce a noise-resistant protocol to\nrealize fast and high-fidelity quantum memory through Hamiltonian engineering.\nWith analytics and numerics, we show that high-fidelity quantum state transfer\nbetween the electron and the nuclear spins is achievable at relatively low\nnuclear polarizations, due to the strong suppression of nuclear spin noises.\nFor a realistic quantum dot with $10^4$ nuclear spins, a fidelity surpassing\n80% is possible at a polarization as low as 30%. Our approach reduces the\ndemand for high nuclear polarization, making experimentally realizing quantum\nmemory in quantum dots more feasible.",
        "positive": "Waveguiding valley excitons in monolayer transition metal dicalcogenides\n  by dielectric interfaces in the substrate: In monolayers of the semiconducting transition metal dichalcogenides, the\nelectron-hole exchange interaction splits the exciton dispersion into a massive\ntransverse branch, and a longitudinal branch that has very light or even zero\nmass depending on the form of screened Coulomb interaction. The group velocity\nof the longitudinal branch is sensitive to the strength of electron-hole\nexchange, which can be engineered through the dielectric environment. Here we\nshow that dielectric patterning of the substrate can be exploited to realize\nwaveguide of the exciton in the longitudinal branch in a homogeneous monolayer,\nleaving the massive transverse branch unaffected. At a lateral interface of\ndifferent dielectric constant in the substrate, the transmission and reflection\nof exciton in the longitudinal branch obey the Snell-Descartes law of optical\nsystem, and total reflection can be exploited to realize excitonic waveguide\nusing two parallel interfaces. The same dielectric pattern of the substrate\nappears to be completely transparent for the massive transverse branch exciton,\nwhich has no interface scattering. When the monolayer is placed on a\none-dimensional dielectric superlattice, the dispersion of the longitudinal\nbranch is strongly renormalized, and the wavefunctions exhibit one-dimensional\nfeatures, confined to either the low-dielectric or high-dielectric regions. In\ncontrast, the massive transverse branch excitons are not affected by the\nsubstrate dielectric pattern, exhibiting pristine properties as in a\nfreestanding monolayer."
    },
    {
        "anchor": "The role of flexural coupling in heat dissipation from a two-dimensional\n  layered material to its hexagonal boron nitride substrate: Understanding the limits of phononic heat dissipation from a two-dimensional\nlayered material (2DLM) to its hexagonal boron nitride (h-BN) substrate and how\nit varies with the structure of the 2DLM is important for the design and\nthermal management of h-BN-supported nanoelectronic devices. We formulate an\nelasticity-based theory to model the phonon-mediated heat dissipation between a\n2DLM and its h-BN substrate. By treating the h-BN substrate as a semi-infinite\nstack of harmonically coupled thin plates, we obtain semi-analytical\nexpressions for the thermal boundary conductance (TBC) and interfacial phonon\ntransmission spectrum. We evaluate the temperature-dependent TBC of the\n$N$-layer 2DLM (graphene or MoS$_{2}$) on different common substrates (h-BN vs.\na-SiO$_{2}$) at different values of $N$. The results suggest that h-BN is\nsubstantially more effective for heat dissipation from MoS$_{2}$ than\na-SiO$_{2}$ especially at large $N$. To understand the limitations of the our\nstack model, we also compare its predictions in the $N=\\infty$ limit to those\nof the more exact Atomistic Green's Function model for the graphite-BN and\nmolybdenite-BN interfaces. Our stack model provides clear insights into the key\nrole of the flexural modes in the TBC and how the anisotropic elastic\nproperties of h-BN affect heat dissipation.",
        "positive": "Inter-shell exchange interaction in CdTe/ZnTe quantum dots:\n  magneto-photoluminescence of X, X2- and XX-: We present a comprehensive photoluminescence study of exchange interaction in\nself-assembled CdTe/ZnTe quantum dots. We exploit the presence of multiple\ncharge states in the photoluminescence spectra of single quantum dots to\nanalyze simultaneously fine structure of different excitonic transitions,\nincluding recombination of neutral exciton/biexciton, doubly charged negative\nexciton and negatively charged biexciton. We demonstrate that the fine\nstructure results from electron-hole exchange interaction and that spin\nHamiltonians with effective exchange constants $\\delta_i$ can provide a good\ndescription of each transition in magnetic field for Faraday and Voigt field\ngeometry. We determine and discuss values of the effective exchange constants\nfor a large statistics of quantum dots."
    },
    {
        "anchor": "Controlling Domain-Wall Nucleation in Ta/CoFeB/MgO Nanomagnets via Local\n  Ga+ Ion Irradiation: Comprehensive control of the domain wall nucleation process is crucial for\nspin-based emerging technologies ranging from random-access and storage-class\nmemories over domain-wall logic concepts to nanomagnetic logic. In this work,\nfocused Ga+ ion-irradiation is investigated as an effective means to control\ndomain-wall nucleation in Ta/CoFeB/MgO nanostructures. We show that analogously\nto He+ irradiation, it is not only possible to reduce the perpendicular\nmagnetic anisotropy but also to increase it significantly, enabling new,\nbidirectional manipulation schemes. First, the irradiation effects are assessed\non film level, sketching an overview of the dose-dependent changes in the\nmagnetic energy landscape. Subsequent time-domain nucleation characteristics of\nirradiated nanostructures reveal substantial increases in the anisotropy fields\nbut surprisingly small effects on the measured energy barriers, indicating\nshrinking nucleation volumes. Spatial control of the domain wall nucleation\npoint is achieved by employing focused irradiation of pre-irradiated magnets,\nwith the diameter of the introduced circular defect controlling the coercivity.\nSpecial attention is given to the nucleation mechanisms, changing from a\nStoner-Wohlfarth particle's coherent rotation to depinning from an anisotropy\ngradient. Dynamic micromagnetic simulations and related measurements are used\nin addition to model and analyze this depinning-dominated magnetization\nreversal.",
        "positive": "Drift-diffusion model for single layer transition metal dichalcogenide\n  field-effect transistors: A physics-based model for the surface potential and drain current for\nmonolayer transition metal dichalcogenide (TMD) field-effect transistor (FET)\nis presented. Taking into account the 2D density-of-states of the atomic layer\nthick TMD and its impact on the quantum capacitance, a model for the surface\npotential is presented. Next, considering a drift-diffusion mechanism for the\ncarrier transport along the monolayer TMD, an explicit expression for the drain\ncurrent has been derived. The model has been benchmarked with a measured\nprototype transistor. Based on the proposed model, the device design window\ntargeting low-power applications is discussed."
    },
    {
        "anchor": "Experimental Clocking of Nanomagnets with Strain for Ultra Low Power\n  Boolean Logic: Nanomagnetic implementations of Boolean logic [1,2] have garnered attention\nbecause of their non-volatility and the potential for unprecedented\nenergy-efficiency. Unfortunately, the large dissipative losses that take place\nwhen nanomagnets are switched with a magnetic field [3], or\nspin-transfer-torque [4] inhibit the promised energy-efficiency. Recently,\nthere have been experimental reports of utilizing the Spin Hall effect for\nswitching magnets [5-7], and theoretical proposals for strain induced switching\nof single-domain magnetostrictive nanomagnets [8-12], that might reduce the\ndissipative losses significantly. Here, we demonstrate, for the first time,\nthat strain-induced switching of single-domain magnetostrictive nanomagnets of\nlateral dimensions ~200 nm fabricated on a piezoelectric substrate can\nimplement a nanomagnetic Boolean NOT gate and unidirectional bit information\npropagation in dipole-coupled nanomagnets chains. This portends\nultra-low-energy logic processors and mobile electronics that may be able to\noperate solely by harvesting energy from the environment without ever requiring\na battery.",
        "positive": "Plasmons in layered structures including graphene: We investigate the optical properties of layered structures with graphene at\nthe interface for arbitrary linear polarization at finite temperature including\nfull retardation by working in the Weyl gauge. As a special case, we obtain the\nfull response and the related dielectric function of a layered structure with\ntwo interfaces. We apply our results to discuss the longitudinal plasmon\nspectrum of several single and double layer devices such as systems with finite\nand zero electronic densities. We further show that a nonhomogeneous dielectric\nbackground can shift the relative weight of the in-phase and out-of-phase mode\nand discuss how the plasmonic mode of the upper layer can be tuned into an\nacoustic mode with specific sound velocity."
    },
    {
        "anchor": "Spin-orbit coupling and spin relaxation of hole states in [001]- and\n  [111]-orientedquantum dots of various geometry: We study the influence of spin-orbit coupling on the hole states in InAs/GaAs\nquantum dots grown on [001]- and [111]-oriented substrates belonging to\nsymmetry point groups: C2v, C3v and D2d. We investigate the impact of various\nspin-orbit mechanisms on the strength of coupling between s- and p-shell\nstates, which is a significant spin-flip channel in quantum dots. We calculate\nspin relaxation rates between the states of lowest Zeeman doublet and show that\nthe [111]-oriented structure offers one order of magnitude slower relaxation\ncompared to the usual [001]-oriented self-assembled QD. The magnetic-field\ndependence of the hole states is calculated using multiband (up to 14 bands)\nk.p model. We identify the irreducible representations linked to the states and\ndiscuss the selection rules, which govern the avoided-crossing pattern in\nmagnetic-field dependence of the energy levels. We show that dominant\ncontribution to the coupling between some of these states comes from the shear\nstrain. On the other hand, we demonstrate no coupling between s- and p-shell\nstates in the [111]-oriented structure.",
        "positive": "Experimental Characterization of Three-Band Braid Relations in\n  Non-Hermitian Acoustic Systems: The nature of complex eigenenergy enables unique band topology to the\nnon-Hermitian (NH) lattice systems. Recently, there has been a fast growing\ninterest in the elusive winding and braiding topologies of the NH single and\ndouble bands, respectively. Here, we explore the even more intricate NH\nmulti-band topology and present the first experimental characterization of the\nthree-band braid relations by acoustic systems. Based on a concise\ntight-binding model, we design a ternary cavity-tube structure equipped with a\nhighly controllable unidirectional coupler, through which the acoustic NH Bloch\nbands are experimentally reproduced in a synthetic dimension. We identify the\nNH three-band braid relations from both the perspectives of eigenvalues and\neigenstates, including a noncommutative braid relation and a swappable braid\nrelation. Our results could promote the understanding of NH Bloch band topology\nand pave the way toward designing new devices for manipulating acoustic states."
    },
    {
        "anchor": "Impurity effects on binding energy, diamagnetic susceptibility and\n  photoionization cross-section of chalcopyrite AgInSe2 Nanotadpole: Recently the interest in chalcopyrite semiconductor nanostructures has\nincreased because of their non-toxicity and their wide direct bandgap.\nLikewise, structures with non-trivial geometry are particularly interesting\nbecause of their electronic, optical, and magnetic properties. In the current\narticle, the finite element method was used in conjunction with the effective\nmass approximation to theoretically investigate the properties of a\nchalcopyrite AgInSe2 nanotadpole in the presence of an off-center impurity. The\nmorphology of the nanotadpole gives it excellent hydrodynamic properties and is\nideal for a wide range of applications. The probability densities for various\nimpurity positions and energy levels were obtained. The results suggested a\nstrong dependence of the behavior of the electron on the impurity positions and\nthe orientation of the wave function. The binding energy's dependence on the\nnanotadpole's size and the impurity position was obtained. The dependence of\nthe diamagnetic susceptibility on the impurity position was calculated. An\nextensive investigation of the photoionization cross-section and the\noscillatory strength was carried out for the ground and the first two excited\nstates as the initial states and the first twenty excited states as the final\nstates.",
        "positive": "Non-local spin valve interferometer: Observation of superconducting spin\n  current and Aharonov-Anandan's non-adiabatic geometric phase: An electron interferometer was designed and fabricated via a normal\nmetal/insulator/ferromagnet non-local lateral spin valve with a ring-shaped\nnormal metal/insulator spacer, and spin current interference was observed. A\nvery high spin signal of 200 m$\\Omega$ was found in a device with 2 $\\mu$m\ninjector-detector distance and magnetic field swept parallel to the plane. With\na perpendicular magnetic field sweep, a Hanle effect measurement showed both\nspin precession and $h/e$ oscillation. Because of the non-adiabatic nature of\nthe precessing spins at low fields as they traverse the normal metal ring, this\nis an experimental observation of Aharonov-Anandan's non-adiabatic geometric\nphase. In addition, our observation of identical spin resistance for normal and\nsuperconducting Aluminum is inconsistent with theoretical predictions based on\nthe quasiparticle picture. To explain the superconducting spin current we\nsuggest that spin triplet Cooper pairs may exist in thin films of Aluminum for\ndirect spin injection."
    },
    {
        "anchor": "Topological Classificaton of Non-Hermitian Gapless Phases: Exceptional\n  Points and Bulk Fermi Arcs: We provide classification of gapless phases in non-Hermitian systems\naccording to two types of complex-energy gaps: point gap and line gap. We show\nthat exceptional points, at which not only eigenenergies but also eigenstates\ncoalesce, are characterized by gap closing of point gaps with nontrivial\ntopological charges. Moreover, we find that bulk Fermi arcs accompanying\nexceptional points are robust because of topological charges for real line\ngaps. On the basis of the classification, some examples are also discussed.",
        "positive": "Brownian refrigeration by hybrid tunnel junctions: Voltage fluctuations generated in a hot resistor can cause extraction of heat\nfrom a colder normal metal electrode of a hybrid tunnel junction between a\nnormal metal and a superconductor. We extend the analysis presented in [Phys.\nRev. Lett. 98, 210604 (2007)] of this heat rectifying system, bearing\nresemblance to a Maxwell's demon. Explicit analytic calculations show that the\nentropy of the total system is always increasing. We then consider a single\nelectron transistor configuration with two hybrid junctions in series, and show\nhow the cooling is influenced by charging effects. We analyze also the cooling\neffect from nonequilibrium fluctuations instead of thermal noise, focusing on\nthe shot noise generated in another tunnel junction. We conclude by discussing\nlimitations for an experimental observation of the effect."
    },
    {
        "anchor": "Magnetoresistance of proximity coupled Au wires: We report measurements of the magnetoresistance (MR) of narrow Au wires\ncoupled to a superconducting Al contact on one end, and a normal Au contact on\nthe other. The MR at low magnetic field $B$ is quadratic in $B$, with a\ncharacteristic field scale $B_c$ determined by phase coherent paths which\nencompass not only the wire, but also the two contacts. $B_c$ is essentially\ntemperature independent at low temperatures, indicating that the area of the\nphase coherent paths is not determined by the superconducting coherence length\n$L_T$ in the normal metal, which is strongly temperature dependent at low\ntemperatures. We identify the relevant length scale as a combination of the\nelectron phase coherence length $L_\\phi$ in the normal metal and the coherence\nlength $\\xi_S$ in the superconductor.",
        "positive": "Powerful energy harvester based on resonant-tunneling quantum wells: We analyze a heat engine based on a hot cavity connected via quantum wells to\nelectronic reservoirs. We discuss the output power as well as the efficiency\nboth in the linear and nonlinear regime. We find that the device delivers a\nlarge power of about 0.18 W/cm^2 for a temperature difference of 1 K nearly\ndoubling the power than can be extracted from a similar heat engine based on\nquantum dots. At the same time, the heat engine also has a good efficiency\nalthough reduced from the quantum dot case. Due to the large level spacings\nthat can be achieved in quantum wells, our proposal opens the route towards\nroom-temperature applications of nanoscale heat engines."
    },
    {
        "anchor": "A simple variational method for calculating energy and quantum\n  capacitance of an electron gas with screened interactions: We describe a variational procedure for calculating the energy of an electron\ngas in which the long-range Coulomb interaction is truncated by the screening\neffect of a nearby metallic gate. We use this procedure to compute the quantum\ncapacitance of the system as a function of electron density and spin\npolarization. The accuracy of the method is verified against published\nMonte-Carlo data. The results compare favorably with a recent experiment.",
        "positive": "Topological magnetic phase transition in Eu-based A-type\n  antiferromagnets: Recently, a colossal magnetoresistance (CMR) was observed in EuCd$_2$P$_2$ --\na compound that does not fit the conventional mixed-valence paradigm. Instead,\nexperimental evidence points at a resistance driven by strong magnetic\nfluctuations within the two-dimensional ($2d$) ferromagnetic (FM) planes of the\nlayered antiferromagnetic (AFM) structure. While the experimental results have\nnot yet been fully understood, a recent theory relates the CMR to a topological\nvortex-antivortex unbinding, i.e., Berezinskii-Kosterlitz-Thouless (BKT), phase\ntransition. Motivated by these observations, in this work we explore the\nmagnetic phases hosted by a microscopic classical magnetic model for\nEuCd$_2$P$_2$, which easily generalizes to other Eu A-type antiferromagnetic\ncompounds. Using Monte Carlo techniques to probe the specific heat and the\nhelicity modulus, we show that our model can exhibit a vortex-antivortex\nunbinding phase transition. We find that this phase transition displays the\nsame sensitivity to in-plane magnetization, interlayer coupling, and easy-plane\nanisotropy that is observed experimentally in the CMR signal, providing\nqualitative numerical evidence that the effect is related to a magnetic BKT\ntransition."
    },
    {
        "anchor": "Shot Noise at High Temperatures: We consider the possibility of measuring non-equilibrium properties of the\ncurrent correlation functions at high temperatures (and small bias). Through\nthe example of the third cumulant of the current (${\\cal{S}}_3$) we demonstrate\nthat odd order correlation functions represent non-equilibrium physics even at\nsmall external bias and high temperatures. We calculate ${\\cal{S}}_3=y(eV/T)\ne^2 I$ for a quasi-one-dimensional diffusive constriction. We calculate the\nscaling function $y$ in two regimes: when the scattering processes are purely\nelastic and when the inelastic electron-electron scattering is strong. In both\ncases we find that $y$ interpolates between two constants. In the low (high)\ntemperature limit $y$ is strongly (weakly) enhanced (suppressed) by the\nelectron-electron scattering.",
        "positive": "Spectral maximum in photoconductance of a quantum point contact: A counter-intuitive disappearance of the giant terahertz photoconductance of\na quantum point contact (QPC) under increase in the photon energy, which was\ndiscovered experimentally (Otteneder et al., Phys. Rev. Applied 10 (2018)\n014015) and studied by the numerical calculations of the photon-stimulated\ntransport (O.A. Tkachenko et al., JETP Lett. 108 (2018) 396), is explained here\nby using qualitative considerations about the momentum conservation upon\nabsorption of terahertz photons. The spectra of photon-stimulated transmission\nthrough a smooth one-dimensional barrier are calculated on the basis of the\nperturbation theory. These calculations also predict the spectral maxima for\noptical transitions from the Fermi level to the top of the potential barrier.\nWithin the proposed physical picture, the widths of the spectral maxima are\nestimated, and the evolution of the shape of the spectra with a change in the\nposition of the Fermi level is qualitatively explained."
    },
    {
        "anchor": "Comment on \"Breaking the theoretical scaling limit for predicting\n  quasi-particle energies: The stochastic GW approach\", by Daniel Neuhauser et\n  al., arXiv:1402.5035v1: We show that the recently-introduced formalism by Neuhauser et al. for the\ncalculation of the quasi-particle energies of electronic systems within the\nframework of the GW approximation of the self-energy operator, named the\n`stochastic GW approach' and empirically shown to have a linear-scaling\narithmetic complexity for increasing number of electrons, suffers from two\nfundamental shortcomings that cannot be overcome while maintaining the present\nempirical linear-scaling property of the approach.",
        "positive": "Effect of inelastic collisions on multiphonon Raman scattering in\n  graphene: We calculate the probabilities of two- and four-phonon Raman scattering in\ngraphene and show how the relative intensities of the overtone peaks encode\ninformation about relative rates of different inelastic processes electrons are\nsubject to. If the most important processes are electron-phonon and\nelectron-electron scattering, the rate of the latter can be deduced from the\nRaman spectra."
    },
    {
        "anchor": "Fano resonance in Raman scattering of graphene: Fano resonances and their strong doping dependence are observed in Raman\nscattering of single-layer graphene (SLG). As the Fermi level is varied by a\nback-gate bias, the Raman G band of SLG exhibits an asymmetric line shape near\nthe charge neutrality point as a manifestation of a Fano resonance, whereas the\nline shape is symmetric when the graphene sample is electron or hole doped.\nHowever, the G band of bilayer graphene (BLG) does not exhibit any Fano\nresonance regardless of doping. The observed Fano resonance can be interpreted\nas interferences between the phonon and excitonic many-body spectra in SLG. The\nabsence of a Fano resonance in the Raman G band of BLG can be explained in the\nsame framework since excitonic interactions are not expected in BLG.",
        "positive": "Gate-electric-field and magnetic-field control of versatile topological\n  phases in a semi-magnetic topological insulator: Surface states of a topological insulator demonstrate interesting quantum\nphenomena, such as the quantum anomalous Hall (QAH) effect and the quantum\nmagnetoelectric effect. Fermi energy tuning plays a role in inducing phase\ntransitions and developing future device functions. Here, we report on\ncontrolling the topological phases in a dual-gate field-effect transistor of a\nsemi-magnetic topological insulator heterostructure. The heterostructure\nconsists of magnetized one-surface and non-magnetic other-surface. By tuning\nthe Fermi energy to the energy gap of the magnetized surface, the Hall\nconductivity $\\sigma_{xy}$ becomes close to the half-integer quantized Hall\nconductivity $e^2/2h$, exemplifying parity anomaly. The dual-gate control\nenables the band structure alignment to the two quantum Hall states with\n$\\sigma_{xy} = e^2/h$ and 0 under a strong magnetic field. These states are\ntopologically equivalent to the QAH and axion insulator states, respectively.\nPrecise and independent control of the band alignment of the top and bottom\nsurfaces successively induces various topological phase transitions among the\nQAH, axion insulator, and parity anomaly states in magnetic topological\ninsulators."
    },
    {
        "anchor": "Coherent Backaction of Quantum Dot Detectors: Qubit Isospin Precession: A sensitive technique for the readout of the state of a qubit is based on the\nmeasurement of the conductance through a proximal sensor quantum dot (SQD).\nHere, we theoretically study the coherent backaction of such a measurement on a\ncoupled SQD-charge-qubit system. We derive Markovian kinetic equations for the\nensemble-averaged state of the SQD-qubit system, expressed in the coupled\ndynamics of two charge-state occupations of the SQD and two qubit isospin\nvectors, one for each SQD charge state. We find that aside from introducing\ndissipation, the detection also renormalizes the coherent evolution of the\nSQD-qubit system. Basically, if the electron on the detector has time to probe\nthe qubit, then it also has time to fluctuate and thereby renormalize the\nsystem parameters. In particular, this induces torques on the qubit isospins,\nsimilar to the spin torque generated by the spintronic exchange field in\nnoncollinear spin-valve structures. Secondly, we show that for a consistent\ndescription of the detection, one must also include the renormalization effects\nin the next-to-leading order in the electron tunneling rates, especially at the\npoint of maximal sensitivity of the detector. Although we focus on a\ncharge-qubit model, our findings are generic for qubit readout schemes that are\nbased on spin-to-charge conversion using a quantum-dot detector. Furthermore,\nour study of the stationary current through the SQD, a test measurement\nverifying that the qubit couples to the detector current, already reveals\nvarious significant effects of the isospin torques on the qubit. Our kinetic\nequations provide a starting point for further studies of the time evolution in\ncharge-based qubit readout. Finally, we provide a rigorous sum rule that\nconstrains such approximate descriptions of the qubit isospin dynamics and show\nthat it is obeyed by our kinetic equations.",
        "positive": "The conditional tunneling time for reflection using the WKB\n  wave-function: We derive an expression for the conditional time for the reflection of a wave\nfrom an arbitrary potential barrier using the WKB wavefunction in the barrier\nregion. Our result indicates that the conditional times for transmission and\nreflection are equal for a symmetric barrier within the validity of the WKB\napproach."
    },
    {
        "anchor": "Quantum dynamics of a resonator driven by a superconducting\n  single-electron transistor: a solid-state analogue of the micromaser: We investigate the behavior of a quantum resonator coupled to a\nsuperconducting single-electron transistor tuned to the Josephson quasiparticle\nresonance and show that the dynamics is similar in many ways to that found in a\nmicromaser. Coupling to the SSET can drive the resonator into non-classical\nstates of self-sustained oscillation via either continuous or discontinuous\ntransitions. Increasing the coupling further leads to a sequence of transitions\nand regions of multistability.",
        "positive": "Circuit QED with fluxonium qubits: theory of the dispersive regime: In circuit QED, protocols for quantum gates and readout of superconducting\nqubits often rely on the dispersive regime, reached when the qubit-photon\ndetuning {\\Delta} is large compared to their mutual coupling strength. For\nqubits including the Cooper-pair box and transmon, selection rules dramatically\nrestrict the contributions to dispersive level shifts {\\chi}. By contrast,\nwithout selection rules many virtual transitions contribute to {\\chi} and can\nproduce sizable dispersive shifts even at large detuning. We present theory for\na generic multi-level qudit capacitively coupled to one or multiple harmonic\nmodes, and give general expressions for the effective Hamiltonian in second and\nfourth order perturbation theory. Applying our results to the fluxonium system,\nwe show that the absence of strong selection rules explains the surprisingly\nlarge dispersive shifts observed in experiments and also leads to the\nprediction of a two-photon vacuum Rabi splitting. Quantitative predictions from\nour theory are in good agreement with experimental data over a wide range of\nmagnetic flux and reveal that fourth-order resonances are important for the\nphase modulation observed in fluxonium spectroscopy."
    },
    {
        "anchor": "Effect of a perpendicular magnetic field on bilayer graphene under dual\n  gating: By studying the impact of a perpendicular magnetic field $B$ on AB-bilayer\ngraphene (AB-BLG) under dual gating, we yield several key findings for the\nballistic transport of gate $U_\\infty$. Firstly, we discover that the presence\nof $B$ leads to a decrease in transmission. At a high value of $B$, we notice\nthe occurrence of anti-Klein tunneling over a significant area. Secondly, in\ncontrast to the results reported in the literature, where high peaks were found\nwith an increasing in-plane pseudomagnetic field applied to AB-BLG, we find a\ndecrease in conductivity as $B$ increases. However, it is worth noting that in\nboth cases, the number of oscillations decreases compared to the result in the\nstudy where no magnetic field was present $(B = 0)$. Thirdly, at the neutrality\npoint, we demonstrate that the conductivity decreases and eventually reaches\nzero for a high value of $B$, which contrasts with the result that the\nconductivity remains unchanged regardless of the value taken by the in-plane\nfield. Finally, we consider the diffusive transport with gate $U_\\infty = 0.2\n\\gamma_1$ and observe two scenarios. The amplitude of conductivity oscillations\nincreases with $B$ for energy $E$ less than $U_\\infty$ but decreases in the\nopposite case $E>U_\\infty$.",
        "positive": "Relaxation dynamics in double-spin systems: We consider the relaxation dynamics of two spins coupled to a common bosonic\nbath. The time evolution is simulated by a generalized master equation derived\nwithin a real-time diagrammatic approach. Interference effects due to the\ncoherent coupling to the common bath give rise to characteristic features in\nthe relaxation dynamics after a quench or during a periodic external driving.\nIn particular, we find that the long-time behavior during periodic driving\ndepends sensitively on the initial state as well as on system parameters such\nas coupling asymmetries. When coupled to more than a single reservoir, the\ninterference effects can lead to a cooling mechanism for one of the bosonic\nreservoirs."
    },
    {
        "anchor": "Emerging nonlinear Hall effect in Kane-Mele two-dimensional topological\n  insulators: The recent observations of nonlinear Hall effect in time-reversal symmetry\nprotected systems and on the surface of three-dimensional topological\ninsulators due to an in-plane magnetic field have attracted immense\nexperimental and theoretical investigations in two-dimensional transition metal\ndichalcogenides and Weyl semimetals. The origin of this type of second order\neffect has been attributed to the emergence of a Berry curvature dipole, which\nrequires a low-symmetry environment. Here, we propose a mechanism for\ngenerating such a second order nonlinear Hall effect in Kane-Mele\ntwo-dimensional topological insulators due to spatial and time reversal\nsymmetry breaking in the presence of Zeeman and Rashba couplings. By actively\ntuning the energy gaps with external electromagnetic fields we also demonstrate\nthat the nonlinear Hall effect shows remarkable signatures of topological phase\ntransitions existing in the considered two-dimensional systems.",
        "positive": "Interference as a Probe of Spin Incoherence in Strongly Interacting\n  Quantum Wires: We show that interference experiments can be used to identify the\nspin-incoherent regime of strongly interacting one-dimensional conductors. Two\nqualitative signatures of spin-incoherence are found: a strong magnetic field\ndependence of the interference contrast and an anomalous scaling of the\ninterference contrast with the applied voltage, with a temperature and magnetic\nfield dependent scaling exponent. The experiments distinguish the\nspin-incoherent from the spin-polarized regime, and so may be useful in\ndeciding between alternative explanations proposed for the anomalous\nconductance quantization observed in quantum point contacts and quantum wires\nat low density."
    },
    {
        "anchor": "Violation and Revival of Kramers' Degeneracy in Open Quantum Systems: Kramers' theorem ensures double degeneracy in the energy spectrum of a\ntime-reversal symmetric fermionic system with half-integer total spin. Here we\nare now trying to go beyond the closed system and discuss Kramers' degeneracy\nin open systems out of equilibrium. In this letter, we prove that the Kramers'\ndegeneracy in interacting fermionic systems is equivalent to the degeneracy in\nthe spectra of different spins together with the vanishing of the inter-spin\nspectrum. We find the violation of Kramers' degeneracy in time-reversal\nsymmetric open quantum systems is locked with whether the system reaches\nthermal equilibrium. After a sudden coupling to an environment in a\ntime-reversal symmetry preserving way, the Kramers doublet experiences an\nenergy splitting at a short time and then a recovery process. We verified the\nviolation and revival of Kramers' degeneracy in a concrete model of interacting\nfermions and we find Kramers' degeneracy is restored after the local\nthermalization time. By contrast, for time-reversal symmetry $\\tilde{\\cal T}$\nwith $\\tilde{\\cal T}^2=1$, we find although there is a violation and revival of\nspectral degeneracy for different spins, the inter-spin spectral function is\nalways nonzero. We also prove that the degeneracy in spectral function\nprotected by unitary symmetry can be maintained always.",
        "positive": "Magnetic field symmetries of nonlinear transport with elastic and\n  inelastic scattering: We study nonlinear electronic transport symmetries in Aharonov-Bohm\ninterferometers subjected to inelastic scattering effects and show that odd\n(even) conductance terms are even (odd) in the magnetic field when the junction\nis (left-right) spatially symmetric. This observation does not hold when an\nasymmetry is introduced, as we show numerically, but odd conductance terms only\nmanifest a weak breakdown of the magnetic field symmetry. Under elastic\ndephasing effects, the Onsager-Casimir symmetry is maintained beyond linear\nresponse and under spatial asymmetries."
    },
    {
        "anchor": "Gaplessness of the Gaffnian: We study the Gaffnian trial wavefunction proposed to describe fractional\nquantum Hall correlations at Bose filling factor $\\nu=2/3$ and Fermi filling\n$\\nu=2/5$. A family of Hamiltonians interpolating between a hard-core\ninteraction for which the physics is known and a projector whose ground state\nis the Gaffnian is studied in detail. We give evidence for the absence of a gap\nby using large-scale exact diagonalizations in the spherical geometry. This is\nin agreement with recent arguments based on the fact that this wavefunction is\nconstructed from a non-unitary conformal field theory. By using the cylinder\ngeometry, we discuss in detail the nature of the underlying minimal model and\nwe show the appearance of heterotic conformal towers in the edge energy\nspectrum where left and right movers are generated by distinct primary\noperators.",
        "positive": "Impurity-directed Transport within a Finite Disordered Lattice: We consider a finite, disordered 1D quantum lattice with a side-attached\nimpurity. We study theoretically the transport of a single electron from the\nimpurity into the lattice, at zero temperature. The transport is dominated by\nAnderson localization and, in general, the electron motion has a random\ncharacter due to the lattice disorder. However, we show that by adjusting the\nimpurity energy the electron can attain quasi-periodic motions, oscillating\nbetween the impurity and a small region of the lattice. This region corresponds\nto the center of a localized state in the lattice with an energy matched by\nthat of the impurity. By precisely tuning the impurity energy, the electron can\nbe set to oscillate between the impurity and a region far from the impurity,\neven distances larger than the Anderson localization length. The electron\noscillations result from the interference of hybridized states, which have some\nresemblance to Pendry's necklace states [J. B. Pendry, J. Phys. C: Solid State\nPhys. 20, 733-742 (1987)]. The dependence of the electron motion on the\nimpurity energy gives a potential mechanism for selectively routing an electron\ntowards different regions of a 1D disordered lattice."
    },
    {
        "anchor": "Cavity QED with Diamond Nanocrystals and Silica Microspheres: Normal mode splitting is observed in a cavity QED system, in which nitrogen\nvacancy centers in diamond nanocrystals are coupled to whispering gallery modes\nin a silica microsphere. The composite nanocrystal-microsphere system takes\nadvantage of the exceptional spin properties of nitrogen vacancy centers as\nwell as the ultra high quality factor of silica microspheres. The observation\nof the normal mode splitting indicates that the dipole optical interaction\nbetween the relevant nitrogen vacancy center and whispering gallery mode has\nreached the strong coupling regime of cavity QED.",
        "positive": "Reduced effective magnetization and damping by slowly-relaxing\n  impurities in strained $\u03b3$-$\\mathrm{Fe_2O_3}$ thin films: We study the static and dynamic magnetic properties of epitaxially strained\n$\\gamma$-$\\mathrm{Fe_2O_3}$ (maghemite) thin films grown via pulsed-laser\ndeposition on MgO substrates by SQUID magnetometry and cryogenic broadband\nferromagnetic resonance experiments. SQUID magnetometry measurements reveal\nhysteretic magnetization curves for magnetic fields applied both in- and out of\nthe sample plane. From the magnetization dynamics of our thin films, we find a\nsmall negative effective magnetization in agreement with a strain induced\nperpendicular magnetic anisotropy. Moreover, we observe a non-linear evolution\nof the ferromagnetic resonance-linewidth as function of the microwave frequency\nand explain this finding with a model based on slowly relaxing impurities, the\nso-called slow relaxor model. By investigating the magnetization dynamics in\nour maghemite thin films as a function of frequency and temperature, we can\nisolate the temperature dependent contribution of the slowly relaxing\nimpurities to the resonance linewidth and, in particular, observe a sign change\nin the effective magnetization. This finding provides evidence for a transition\nof the magnetic anisotropy from a perpendicular easy axis to an easy in-plane\nanisotropy for reduced temperatures."
    },
    {
        "anchor": "Delay times in chaotic quantum systems: By an inductive reasoning, and based on recent results of the joint moments\nof proper delay times of open chaotic systems for ideal coupling to leads, we\nobtain a general expression for the distribution of the partial delay times for\nan arbitrary number of channels and any symmetry. This distribution was not\ncompletely known for all symmetry classes. Our theoretical distribution is\nverified by random matrix theory simulations of ballistic chaotic cavities.",
        "positive": "Large enhancement in thermoelectric efficiency of quantum dot junction\n  due to increase of level degeneracy: It is theoretically demonstrated that the figure of merit ($ZT$) of quantum\ndot (QD) junctions can be significantly enhanced when the degree of degeneracy\nof the energy levels involved in electron transport is increased. The theory is\nbased on the the Green-function approach in the Coulomb blockade regime by\nincluding all correlation functions resulting from electron-electron\ninteractions associated with the degenerate levels ($L$). We found that\nelectrical conductance ($G_e$) as well as electron thermal conductance\n($\\kappa_e$) are highly dependent on the level degeneracy ($L$), whereas the\nSeebeck coefficient ($S$) is not. Therefore, the large enhancement of $ZT$ is\nmainly attributed to the increase of $G_e$ when the phonon thermal conductance\n($\\kappa_{ph}$) dominates the heat transport of QD junction system. In the\nserially coupled double-QD case, we also obtain a large enhancement of $ZT$\narising from higher $L$. Unlike $G_e$ and $\\kappa_e$, $S$ is found almost\nindependent on electron inter-dot hopping strength."
    },
    {
        "anchor": "Exciton-Polaritons in Hybrid Inorganic-organic Perovskite Fabry-P\u00e9rot\n  Microcavity: Exciton-polaritons in semiconductor microcavities generate fascinating\neffects such as long-range spatial coherence and Bose-Einstein Condensation\n(BEC), which are attractive for their potential use in low threshold lasers,\nvortices and slowing light, etc. However, currently most of exciton-polariton\neffects either occur at cryogenic temperature or rely on expensive cavity\nfabrication procedures. Further exploring new semiconductor microcavities with\nstronger exciton photon interaction strength is extensively needed. Herein, we\ndemonstrate room temperature photon exciton strong coupling in hybrid\ninorganic-organic CH3NH3PbBr3 Fabry-P\\'erot microcavities for the first time.\nThe vacuum Rabi splitting energy is up to ~390 meV, which is ascribed to large\noscillator strength and photon confinement in reduced dimension of optical\nmicrocavities. With increasing pumping energy, exciton-photon coupling strength\nis weakened due to carrier screening effect, leading to occurrence of photonic\nlasing instead of polartion lasing. The demonstrated strong coupling between\nphotons and excitons in perovskite microcavities would be helpful for\ndevelopment of high performance polariton-based incoherent and coherent light\nsources, nonlinear optics, and slow light applications.",
        "positive": "Efficient computation of demagnetising fields for magnetic multilayers\n  using multilayered convolution: As research into magnetic thin films and spintronics devices is moving from\nsingle to multiple magnetic layers, there is a need for micromagnetics\nmodelling tools specifically designed to efficiently handle magnetic\nmultilayers. Here we show an exact method of computing demagnetising fields in\nmagnetic multilayers, which is able to handle layers with arbitrary spacing,\narbitrary thicknesses, and arbitrary relative positioning between them without\nimpacting on the computational performance, or sacrificing numerical accuracy.\nThe multilayered convolution method is a generalisation of the well-known\nconvolution method used to compute demagnetising fields in a single magnetic\nbody. In typical use cases, such as multilayered stacks used to study\nskyrmions, we show the multilayered convolution method can be up to 8 times\nfaster, implemented both for central processors and graphics processors,\ncompared to the simple convolution method."
    },
    {
        "anchor": "Theory of the Spontaneous Emission in Photonic and Plasmonic\n  Nanoresonators: We provide a self-consistent electromagnetic theory of the coupling between\ndipole emitters and dissipative nanoresonators. The theory that relies on the\nconcept of quasi-normal modes with complex frequencies provides an accurate\nclosed-form expression for the electromagnetic local density of states (LDOS)\nof any photonic or plasmonic resonator with strong radiation leakage,\nabsorption and material dispersion. It represents a powerful tool to calculate\nand conceptualize the electromagnetic response of systems that are governed by\na small number of resonance modes. We use the formalism to revisit Purcell's\nfactor. The new formula substantially differs from the usual one; in\nparticular, it predicts that a spectral detuning between the emitter and the\nresonance does not necessarily result in a Lorentzian response in the presence\nof dissipation. Comparisons with fully-vectorial numerical calculations for\nplasmonic nanoresonators made of gold nanorods evidence the high accuracy of\nthe predictions achieved by our semi-analytical treatment.",
        "positive": "Projected Topological Branes: Nature harbors crystals of dimensionality ($d$) only up to three. Here we\nintroduce the notion of \\emph{projected topological branes} (PTBs):\nLower-dimensional branes embedded in higher-dimensional parent topological\ncrystals, constructed via a geometric cut-and-project procedure on the Hilbert\nspace of the parent lattice Hamiltonian. When such a brane is inclined at a\nrational or an irrational slope, either a new lattice periodicity or a\nquasicrystal emerges. The latter gives birth to topoquasicrystals within the\nlandscape of PTBs. As such PTBs are shown to inherit the hallmarks, such as the\nbulk-boundary, bulk-dislocation correspondences and topological invariant, of\nthe parent topological crystals. We exemplify these outcomes by focusing on\ntwo-dimensional parent Chern insulators, leaving its signatures on projected\none-dimensional (1D) topological branes in terms of localized endpoint,\ndislocation modes and the local Chern number. Finally, by stacking 1D projected\nChern insulators, we showcase the imprints of three-dimensional Weyl semimetals\nin $d=2$, namely the Fermi arc surface states and bulk chiral zeroth Landau\nlevel, responsible for the chiral anomaly. Altogether, the proposed PTBs open a\nrealistic avenue to harness higher-dimensional ($d>3$) topological phases in\nlaboratory."
    },
    {
        "anchor": "High Mobility Ambipolar MoS2 Field-Effect Transistors: Substrate and\n  Dielectric Effects: We fabricate MoS2 field effect transistors on both SiO2 and polymethyl\nmethacrylate (PMMA) dielectrics and measure charge carrier mobility in a\nfour-probe configuration. For multilayer MoS2 on SiO2, the mobility is 30-60\ncm2/Vs, relatively independent of thickness (15-90 nm), and most devices\nexhibit unipolar n-type behavior. In contrast, multilayer MoS2 on PMMA shows\nmobility increasing with thickness, up to 470 cm2/Vs (electrons) and 480 cm2/Vs\n(holes) at thickness ~50 nm. The dependence of the mobility on thickness points\nto a long-range dielectric effect of the bulk MoS2 in increasing mobility.",
        "positive": "Indirect exciton qubit manipulation via the optical Stark effect in\n  quantum dot molecules: We propose a coherent control scheme based on the optical Stark effect in\noptically generated excitons in quantum dot molecules (QDMs). We show that, by\nthe combined action of voltage bias detuning sweeps and Rosen-Zener pulsed\ninteractions, it is possible to dynamically generate and modify an anticrossing\ngap that emerges between the dressed energy levels of long-lived, spatially\nindirect excitons. We perform numerical and analytic non-perturbative\ncalculations based on the Bloch-Feshbach formalism, which demonstrate that this\neffect induces a mechanism of coherent population trapping of indirect excitons\nin QDMs. Our results show that it is possible to perform an all-optical\nimplementation of indirect-excitonic qubit operations, such as the Pauli-X and\nHadamard quantum gates, across two defined axis of the Bloch Sphere."
    },
    {
        "anchor": "Local gating of a graphene Hall bar by graphene side gates: We have investigated the magnetotransport properties of a single-layer\ngraphene Hall bar with additional graphene side gates. The side gating in the\nabsence of a magnetic field can be modeled by considering two parallel\nconducting channels within the Hall bar. This results in an average penetration\ndepth of the side gate created field of approx. 90 nm. The side gates are also\neffective in the quantum Hall regime, and allow to modify the longitudinal and\nHall resistances.",
        "positive": "Localization in an imaginary vector potential: Eigenfunctions of 1d disordered Hamiltonian with constant imaginary vector\npotential are investigated. Even within the domain of complex eigenvalues the\nwave functions are shown to be strongly localized. However, this localization\nis of a very unusual kind. The logarithm of the wave function at different\ncoordinates $x$ fluctuates strongly (just like the position of Brownian\nparticle fluctuates in time). After approaching its maximal value the logarithm\ndecreases like the square root of the distance $\\bar{(\\ln|\\psi_{max}/\\psi|)^2}\n\\sim |x-x_0|$. The extension of the model to the quasi-1d case is also\nconsidered."
    },
    {
        "anchor": "Anomalous Diffusion in Quasi One Dimensional Systems: In order to perform quantum Hamiltonian dynamics minimizing localization\neffects, we introduce a quasi-one dimensional tight-binding model whose mean\nfree path is smaller than the size of the sample. This one, in turn, is smaller\nthan the localization length. We study the return probability to the starting\nlayer of the system by means of direct diagonalization of the Hamiltonian. We\ncreate a one dimensional excitation and observe sub-diffusive behavior for\ntimes larger than the Debye time but shorter than the Heisenberg time. The\nexponent corresponds to the fractal dimension $d^{*} \\sim 0.72$ which is\ncompared to that calculated from the eigenstates by means of the inverse\nparticipation number.",
        "positive": "The effect of magnetic impurity scattering on transport in topological\n  insulators: Charge transport in topological insulators is primarily characterised by\nso-called topologically projected helical edge states, where charge carriers\nare correlated in spin and momentum. In principle, dissipation-less current can\nbe carried by these edge states as backscattering from impurities and defects\nis suppressed as long as time-reversal symmetry is not broken. However, applied\nmagnetic fields or underlying nuclear spin-defects in the substrate can break\nthis time reversal symmetry. In particular, magnetic impurities lead to\nback-scattering by spin-flip processes. We have investigated the effects of\npoint-wise magnetic impurities on the transport properties of helical edge\nstates in the BHZ model using the Non-Equilibrium Green's Function formalism\nand compared the results to a semi-analytic approach. Using these techniques we\nstudy the influence of impurity strength and spin impurity polarization. We\nobserve a secondary effect of defect-defect interaction that depends on the\nunderlying material parameters which introduces a non-monotonic response of the\nconductance to defect density. This in turn suggests a qualitative difference\nin magneto-transport signatures in the dilute and high density spin impurity\nlimits."
    },
    {
        "anchor": "Open source FCI code for quantum dots and effective interactions: We describe OpenFCI, an open source implementation of the full\nconfiguration-interaction method (FCI) for two-dimensional quantum dots with\noptional use of effective renormalized interactions. The code is written in C++\nand is available under the Gnu General Public License. The code and core\nlibraries are well documented and structured in a way such that customizations\nand generalizations to other systems and numerical methods are easy tasks. As\nexamples we provide a matrix element tabulation program and an implementation\nof a simple model from nuclear physics, in addition to the quantum dot\napplication itself.",
        "positive": "Vertical absorption edge and universal onset conductance in\n  semi-hydrogenated graphene: We show that for graphene with any finite difference in the on-site energy\nbetween the two sub-lattices ($\\Delta$), The optical absorption edge is\ndetermined by the $\\Delta$. The universal conductance will be broken and the\nconductance near the band edge varies with frequency as $1/\\omega^2$. Moreover,\nwe have identified another universal conductance for such systems without\ninversion symmetry, i.e., the onset conductance at the band edge is $%\n\\sigma_c=2\\sigma_0=\\pi e^2/2h$, independent of the size of the band gap. The\ntotal integrated optical response is nearly conserved despite of the opening of\nthe band gap."
    },
    {
        "anchor": "Three-dimensional Resonant Magnetization Dynamics Unraveled by\n  Time-Resolved Soft X-ray Laminography: The imaging of magneto-dynamical processes has been, so far, mostly a\ntwo-dimensional business, due to the constraints of the available experimental\ntechniques. In this manuscript, building on the recent developments of soft\nX-ray magnetic laminography, we present an experimental setup where\nmagneto-dynamical processes can be resolved in all three spatial dimensions and\nin time, with the possibility to freely tune the frequency of the dynamical\nprocess. We then employ this setup to investigate the three-dimensional\ndynamics of two resonant magneto-dynamical modes in a CoFeB microstructure\noccurring at different frequencies, namely the fundamental vortex gyration mode\nand a magnetic field-induced domain wall excitation mode. This new technique\nprovides much needed capabilities for the experimental investigation of the\nmagnetization dynamics of three-dimensional magnetic systems.",
        "positive": "Substrate Induced Molecular Conformations in Rubrene Thin Films: A\n  Thickness Dependent Study: A systematic experimental and theoretical study about substrate induced\nmolecular conformation in rubrene thin films by varying film thickness from\nsub-monolayer to multilayer, which currently attracts substantial attention\nwith regard to its application in organic electronics, is performed. The clean\npolycrystalline Au and Ag were used as noble-metals, whereas, H passivated and\nSiO2 terminated Si (100) were used as dielectric substrates. Angle dependent\nnear edge x-ray absorption fine structure spectroscopy (NEXAFS) was employed to\nunderstand the molecular conformation whereas atomic force microscopy (AFM) was\nused to investigate the surface morphologies of the films. X-ray absorption\nspectra (XAS) of rubrene molecules with flat and twisted conformations were\ncalculated using density functional theory (DFT). All the observed NEXAFS\nspectra of rubrene thin films at various thicknesses and onto different\nsubstrates were explained in terms of different combination of the spectral\nintensity from the twisted and the flat molecules. In contrast to general\nfindings, comparatively rough polycrystalline Ag surface is found to support\ngrowth of better quality rubrene films. The results have important implications\nfor the understanding of the substrate induced molecular conformations in\nrubrene thin films with its thickness and are beneficial for the improvement of\nthe device performance."
    },
    {
        "anchor": "Energy Level Lifetimes in the Single-Molecule Magnet Fe_8 : Experiments\n  and Simulations: We present pump-probe measurements on the single-molecule magnet Fe_8 with\nmicrowave pulses having a length of several nanoseconds. The microwave\nradiation in the experiments is located in the frequency range between 104 GHz\nand 118 GHz. The dynamics of the magnetization of the single Fe_8 crystal is\nmeasured using micrometer-sized Hall sensors. This technique allows us to\ndetermine the level lifetimes of excited spin states, that are found to be in\ngood agreement with theoretical calculations. The theory, to which we compare\nour experimental results, is based on a general spin-phonon coupling formalism,\nwhich involves spin transitions between nearest and next-nearest energy levels.\nWe show that good agreement between theory and experiments is only obtained\nwhen using both the Delta m_S = +-1 transition as well as Delta m_S = +-2,\nwhere Delta m_S designates a change in the spin quantum number m_S. Temperature\ndependent studies of the level lifetimes of several spin states allow us\nfinally to determine experimentally the spin-phonon coupling constants.",
        "positive": "Scale-invariant large nonlocality in polycrystalline graphene: The observation of large nonlocal resistances near the Dirac point in\ngraphene has been related to a variety of intrinsic Hall effects, where the\nspin or valley degrees of freedom are controlled by symmetry breaking\nmechanisms. Engineering strong spin or valley Hall signals on scalable graphene\ndevices could stimulate further practical developments of spin- and\nvalleytronics. Here we report on scale-invariant nonlocal transport in\nlarge-scale chemical vapour deposition graphene under an applied external\nmagnetic field. Contrary to previously reported Zeeman spin Hall effect, our\nresults are explained by field-induced spin-filtered edge states whose\nsensitivity to grain boundaries manifests in the nonlocal resistance. This\nphenomenon, related to the emergence of the quantum Hall regime, persists up to\nthe millimeter scale, showing that polycrystalline morphology can be imprinted\nin nonlocal transport. This suggests that topological Hall effects in\nlarge-scale graphene materials are highly sensitive to the underlying\nstructural morphology, limiting practical realizations."
    },
    {
        "anchor": "Reconstruction-induced trefoil knot Fermi contour of Au(111): Using angle-resolved photoemission spectroscopy (ARPES), we study the effect\nof the so-called herringbone reconstruction of Au(111) on the dispersion of the\nfree electron-like surface state. While earlier ARPES investigations have only\nreported a minor interplay of the surface state dispersion and the underlying\nreconstruction, we show that the uniaxial lattice distortion and the thereby\nchanged reciprocal lattice for the first atomic layer leads to distinct surface\nstate dispersions around the first order reciprocal lattice points of the three\ndomains, creating a constant energy surface resembling a trefoil knot. The\nfindings resolve the long-standing discrepancy between, on one hand, the\nreconstruction-induced surface state modifications reported in scanning\ntunnelling microscopy and first principle calculations and, on the other hand,\ntheir conspicuous absence in photoemission.",
        "positive": "Fluctuation Theorem in a Quantum-Dot Aharonov-Bohm Interferometer: In the present study, we investigate the full counting statistics in a\ntwo-terminal Aharonov-Bohm interferometer embedded with an interacting quantum\ndot. We introduce a novel saddle-point solution for a cumulant-generating\nfunction, which satisfies the fluctuation theorem and accounts for the\ninteraction in the mean-field level approximation. Nonlinear transport\ncoefficients satisfy universal relations imposed by microscopic reversibility,\nthough the scattering matrix itself is not reversible. The skewness can be\nfinite even in equilibrium, owing to the interaction and is proportional to the\nasymmetric component of nonlinear conductance."
    },
    {
        "anchor": "Inelastic Interaction Corrections and Universal Relations for Full\n  Counting Statistics: We analyze in detail the interaction correction to Full Counting Statistics\n(FCS) of electron transfer in a quantum contact originating from the\nelectromagnetic environment surrounding the contact. The correction can be\npresented as a sum of two terms, corresponding to elastic/inelastic electron\ntransfer. Here we primarily focus on the inelastic correction.\n  For our analysis, it is important to understand more general -- universal --\nrelations imposed on FCS only by quantum mechanics and statistics with no\nregard for a concrete realization of a contact. So we derive and analyze these\nrelations. We reveal that for FCS the universal relations can be presented in a\nform of detailed balance. We also present several useful formulas for the\ncumulants.\n  To facilitate the experimental observation of the effect, we evaluate\ncumulants of FCS at finite voltage and temperature. Several analytical results\nobtained are supplemented by numerical calculations for the first three\ncumulants at various transmission eigenvalues.",
        "positive": "Non-local transport in normal-metal/superconductor hybrid structures:\n  the role of interference and interaction: We have measured local and non-local conductance of mesoscopic\nnormal-metal/superconductor hybrid structures fabricated by e-beam lithography\nand shadow evaporation. The sample geometry consists of a superconducting\naluminum bar with two normal-metal wires forming tunnel contacts to the\naluminum at distances of the order of the superconducting coherence length. We\nobserve subgap anomalies in both local and non-local conductance that quickly\ndecay with magnetic field and temperature. For the non-local conductance both\npositive and negative signs are found as a function of bias conditions,\nindicating at a competition of crossed Andreev reflection and elastic\ncotunneling. Our data suggest that the signals are caused by a phase-coherent\nenhancement of transport rather than dynamical Coulomb blockade."
    },
    {
        "anchor": "Entanglement spectroscopy of a driven solid-state qubit and its detector: We study the asymptotic dynamics of a driven quantum two level system coupled\nvia a quantum detector to the environment. We find multi-photon resonances\nwhich are due to the entanglement of the qubit and the detector. Different\nregimes are studied by employing a perturbative Floquet-Born-Markov approach\nfor the qubit+detector system, as well as non-perturbative real-time path\nintegral schemes for the driven spin-boson system. We find analytical results\nfor the resonances, including the red and the blue sidebands. They agree well\nwith those of exact ab-initio calculations.",
        "positive": "Tunable Surface Plasmon Polaritons in a Weyl Semimetal Waveguide: Weyl semimetals have recently attracted extensive attention due to their\nanomalous band structure manifested by topological properties that lead to some\nunusual and unique physical properties. We investigate novel features of\nsurface plasmon polaritons in a slot waveguide comprised from two semi-infinite\nWeyl semimetals. We consider symmetric Voigt-Voigt and Faraday-Faraday\nconfigurations for plasmon polaritons in two interfaces of waveguide and show\nthat the resulting dispersion is symmetric and the propagation of surface\nplasmon polaritons is bidirectional. We introduce exotic and novel asymmetric\nstructures making use of difference in magnitude or orientation of chiral\nanomalies in two Weyl semimetals in both Voigt and Faraday configurations.\nThese structures show a tremendous nonreciprocal dispersion and unidirectional\npropagation of surface plasmon polaritons. Moreover, we study an hybrid\nconfiguration of Voigt-Faraday for surface plasmon polartions in two interfaces\nof the waveguide. We find that this structure possesses unique futures. It\nshows surface plasmon polariton modes with unidirectional propagation above the\nbulk plasmon frequency. Furthermore, we find a surface plasmon polariton band\nwhich admits the Voigt and Faraday features simultaneously. Also, we show that\nthe waveguide thickness and the chemical potential of the Weyl semimetals can\nbe used as a fine-tuning parameters in these structures. Our findings may be\nemployed in optical devices which exploit the unidirectional surface plasmon\npropagation features."
    },
    {
        "anchor": "Selective generation and amplification of RKKY interactions by P-N\n  interface: We propose a physical mechanism to generate and selectively amplify\nanisotropic Rudermann-Kittel-Kasuya-Yosida (RKKY) interactions between two\nlocal spins. The idea is to combine the deflection of the carrier velocity by a\nP-N interface and the locking of this velocity to the carrier spin orientation\nvia spin-orbit coupling. We provide analytical and numerical results to\ndemonstrate this mechanism on the surface of a topological insulator P-N\njunction. This work identifies the P-N interface as a second knob which,\ntogether with the carrier density, enables independent control of the strength\nand anisotropy of the RKKY interaction over a wide range. These findings may be\nrelevant to scalable quantum computation and two-impurity quantum criticality.",
        "positive": "1/f Flux Noise in low-T$_c$ SQUIDs due to Superparamagnetic Phase\n  Transitions in Defect Clusters: It is shown here that $1/f^\\alpha$ flux noise in conventional low-T$_c$\nSQUIDs is a result of low temperature superparamagnetic phase transitions in\nsmall clusters of strongly correlated color center defects. The spins in each\ncluster interact via long-range ferromagnetic interactions. Due to its small\nsize, the cluster behaves like a 'random-telegraphic' macro-spin when\ntransitioning to the superparamagnetic phase. This results in $1/f^{\\alpha}$\nnoise when ensemble averaged over a random distribution of clusters. This model\nis self-consistent and explains all related experimental results which includes\n$\\alpha\\sim 0.8$ independent of system-size. The experimental\nflux-inductance-noise spectrum is explained through three-point correlation\ncalculations and time reversal symmetry breaking arguments. Also, unlike the\nflux noise, it is shown why the second-spectrum inductance noise is inherently\ntemperature dependent due to the fluctuation-dissipation theorem. A\ncorrelation-function calculation methodology using Ising-Glauber dynamics was\nkey for obtaining these results."
    },
    {
        "anchor": "Pseudospin dynamics in multimode polaritonic Josephson junctions: We analyzed multimode Josephson junctions with exciton-polaritons\n(polaritonic Josephson junctions) when several coupling mechanisms of\nfundamental and excited states are present. The applied method is based on\nKeldysh-Green function formalism and takes into account polariton pseudospin.\nWe found that mean value of circular polarization degree in intrinsic Josephson\noscillations and microscopic quantum self-trapping follow an oscillator\nbehavior whose renormalizes due to intermode interactions. The effect of an\nadditional transfer of particles over junction barrier occurring in multimode\napproximation in combination with common Josephson tunneling is discussed in\nregime of dynamical separation of two polarizations.",
        "positive": "Non-Hermitian topological phenomena: A review: The past decades have witnessed an explosion of interest in topological\nmaterials, and a lot of mathematical concepts have been introduced in condensed\nmatter physics. Among them, the bulk-boundary correspondence is the central\ntopic in topological physics, which has inspired researchers to focus on\nboundary physics. Recently, the concepts of topological phases have been\nextended to non-Hermitian Hamiltonians, whose eigenvalues can be complex.\nBesides the topology, non-Hermiticity can also cause a boundary phenomenon\ncalled the non-Hermitian skin effect, which is an extreme sensitivity of the\nspectrum to the boundary condition. In this article, we review developments in\nnon-Hermitian topological physics by focusing mainly on the boundary problem.\nAs well as the competition between non-Hermitian and topological boundary\nphenomena, we discuss the topological nature inherent in non-Hermiticity\nitself."
    },
    {
        "anchor": "Numerical simulation method for Brownian particles dispersed in\n  incompressible fluids: We present a numerical scheme for simulating the dynamics of Brownian\nparticles suspended in a fluid. The motion of the particles is tracked by the\nLangevin equation, whereas the host fluid flow is analyzed by using the lattice\nBoltzmann method. The friction force between a particle and the fluid is\nevaluated correctly based on the velocity difference at the position of the\nparticle. The coupling method accurately reproduces the long-time tail observed\nin the velocity auto-correlation function. We also show that the\nfluctuation-dissipation relation holds between the relaxation of a single\nparticle and the velocity autocorrelation function of fluctuating particles.",
        "positive": "An accurate single-electron pump based on a highly tunable silicon\n  quantum dot: Nanoscale single-electron pumps can be used to generate accurate currents,\nand can potentially serve to realize a new standard of electrical current based\non elementary charge. Here, we use a silicon-based quantum dot with tunable\ntunnel barriers as an accurate source of quantized current. The charge transfer\naccuracy of our pump can be dramatically enhanced by controlling the\nelectrostatic confinement of the dot using purposely engineered gate\nelectrodes. Improvements in the operational robustness, as well as suppression\nof non-adiabatic transitions that reduce pumping accuracy, are achieved via\nsmall adjustments of the gate voltages. We can produce an output current in\nexcess of 80 pA with experimentally determined relative uncertainty below 50\nparts per million."
    },
    {
        "anchor": "Singlet-triplet minus mixing and relaxation lifetimes in a double donor\n  dot: We measure singlet-triplet mixing in a precision fabricated double donor dot\ncomprising of 2 and 1 phosphorus atoms separated by $16{\\pm}1$ nm. We identify\nsinglet and triplet-minus states by performing sequential independent spin\nreadout of the two electron system and probe its dependence on magnetic field\nstrength. The relaxation of singlet and triplet states are measured to be\n$12.4{\\pm}1.0$ s and $22.1{\\pm}1.0$ s respectively at $B_z{=}2.5$ T.",
        "positive": "Dissipation due to tunneling two-level systems in gold nanomechanical\n  resonators: We present measurements of the dissipation and frequency shift in\nnanomechanical gold resonators at temperatures down to 10 mK. The resonators\nwere fabricated as doubly-clamped beams above a GaAs substrate and actuated\nmagnetomotively. Measurements on beams with frequencies 7.95 MHz and 3.87 MHz\nrevealed that from 30 mK to 500 mK the dissipation increases with temperature\nas $T^{0.5}$, with saturation occurring at higher temperatures. The relative\nfrequency shift of the resonators increases logarithmically with temperature up\nto at least 400 mK. Similarities with the behavior of bulk amorphous solids\nsuggest that the dissipation in our resonators is dominated by two-level\nsystems."
    },
    {
        "anchor": "Kondo ground state in a quantum dot with an even number of electrons: Kondo conduction has been observed in a quantum dot with an even number of\nelectrons at the Triplet-Singlet degeneracy point produced by applying a small\nmagnetic field $B$ orthogonal to the dot plane.\n  At a much larger field $ B \\sim B_*$, orbital effects induce the reversed\ntransition from the Singlet to the Triplet state. We study the newly proposed\nKondo behavior at this point. Here the Zeeman spin splitting cannot be\nneglected, what changes the nature of the Kondo coupling. On grounds of exact\ndiagonalization results in a dot with cylindrical symmetry, we show that, at\nodds with what happens at the other crossing point, close to $B_*$, orbital and\nspin degrees of freedom are ``locked together'', so that the Kondo coupling\ninvolves a fictitious spin 1/2 only, which is fully compensated by conduction\nelectrons under suitable conditions. In this sense, spin at the dot is\nfractionalized. We derive the scaling equation of the system by means of a\nnonperturbative variational approach. The approach is extended to the $B \\neq\nB_*$-case and the residual magnetization on the dot is discussed.",
        "positive": "Single and Few-Particle States in Core-Shell Nanowire Quantum Dots: The electronic properties of single and few-particles in core-shell nanowire\nquantum dots (NWQD) are investigated. By performing configuration interaction\n(CI) calculations we particularly elucidate how elevated symmetry character\n(C3v or D2d) exhibited by single particle orbitals enhances the phase coherence\nof exciton-photon wavefunction though suppressing spin flip processes. Detailed\ncalculations presented here demonstrate how strain-induced potentials\nmanipulate the symmetry characters, intrinsic oscillator strength and\nelectron-hole dipole in NWQDs. An orbital-dependent kinetic energy is defined\nbased on single particle dispersion and orbital spreadout in k-space. It is\nshown the exchange occurring between this kinetic energy and strain-induced\npotentials is responsible for orbital distortions, and thus the energy\nreordering of different direct and correlation terms. Various structures have\nbeen examined to elaborate on the influence of size and orientation together\nwith axial and lateral symmetry of NWQDs. Our many-body calculations suggest\nthat binding energies of s-shell few particle resonances XX0 and trions are\nsuppressed when axial and lateral localizations become comparable. Then\nexerting an external perturbation may renormalize the binding energies,\nrealizing a transition from anti-binding to binding regime or reverse. In this\nregard, we specifically show that kinetic energy of single particles, and thus\ncorrelation energies of associated complexes, exposed to an electric field\nremain relatively unaffected and the interplay between direct Coulomb terms\nreorders the multiexcitonic resonances. Sub-micro-eV fine structure splitting\nalong with the tunable XX0 binding energy offers NWQDs promising for generating\nentangled photons in both regular and time reordering schemes."
    },
    {
        "anchor": "Husimi function for electrons moving in magnetic fields: Husimi functions allow one to obtain sensible and useful phase space\nprobability distributions from quantumechanical wavefunctions or classical wave\nfields, linking them to (semi-)classical methods and intuition. They have been\nused in several fields of physics, including electronic transport. We show that\napplying Husimi functions to ballistic electron dynamics in magnetic fields\nneeds special consideration in order for them to obey gauge invariance and\nenergy conservation. We therefore extend the Husimi function formalism to allow\nfor magnetic fields making use of magnetic translation operators. We\ndemonstrate the application in tight-binding magneto-transport calculations in\ngraphene nanodevices, highlighting connections with Klein tunneling. In\ncontinuation of recent work, with this paper we further pave the way for using\nthe Husimi function to unravel quantum transport phenomena in nanodevices.",
        "positive": "Contact morphology and revisited photocurrent dynamics in monolayer MoS2: Two-dimensional (2D) layered transition metal dichalcogenides (TMDs) have\nemerged as promising materials for electronic, optoelectronic, and valleytronic\napplications. Recent work suggests drastic changes of the band gap and exciton\nbinding energies of photo-excited TMDs with ultrafast non-radiative relaxation\nprocesses effectively heating the crystal lattice. Such phenomena have not been\nconsidered in the context of optoelectronic devices yet. We resolve\ncorresponding ultrafast photo-conductance dynamics within monolayer MoS2 and\ndemonstrate that a bolometric contribution dominates the overall\nphotoconductance. We further reveal that a focused laser illumination, as is\nused in many standard optoelectronic measurements of MoS2, modifies and anneals\nthe morphology of metal contacts. We show that a junction evolves with lateral\nbuilt-in electric fields, although Raman- and photoluminescence spectra\nindicate no significant changes such as a crystal phase transition. We\nhighlight how such optimized devices can drive ultrafast electromagnetic\nsignals in on-chip high-frequency and THz circuits."
    },
    {
        "anchor": "A Non-Demolition Single Spin Meter: We present the theory of a single spin meter consisting of a quantum dot in a\nmagnetic field under microwave irradiation combined with a charge counter. We\nshow that when a current is passed through the dot, a change in the average\noccupation number occurs if the microwaves are resonant with the on-dot Zeeman\nsplitting. The width of the resonant change is given by the microwave induced\nRabi frequency, making the quantum dot a sensitive probe of the local magnetic\nfield and enabling the detection of the state of a nearby spin. If the dot-spin\nand the nearby spin have different g-factors a non-demolition readout of the\nspin state can be achieved. The conditions for a reliable spin readout are\nfound.",
        "positive": "Spin caloritronic nano-oscillator: Energy loss due to ohmic heating is a major bottleneck limiting down-scaling\nand speed of nano-electronic devices, and harvesting ohmic heat for signal\nprocessing is a major challenge in modern electronics. Here we demonstrate that\nthermal gradients arising from ohmic heating can be utilized for excitation of\ncoherent auto-oscillations of magnetization and for generation of tunable\nmicrowave signals. The heat-driven dynamics is observed in\n$\\mathrm{Y_{3}Fe_{5}O_{12}/Pt}$ bilayer nanowires where ohmic heating of the Pt\nlayer results in injection of pure spin current into the\n$\\mathrm{Y_{3}Fe_{5}O_{12}}$ layer. This leads to excitation of\nauto-oscillations of the $\\mathrm{Y_{3}Fe_{5}O_{12}}$ magnetization and\ngeneration of coherent microwave radiation. Our work paves the way towards spin\ncaloritronic devices for microwave and magnonic applications."
    },
    {
        "anchor": "Dynamics of excitons in individual InAs quantum dots revealed in\n  four-wave mixing spectroscopy: A detailed understanding of the population and coherence dynamics in\noptically driven individual emitters in solids and their signatures in\nultrafast nonlinear-optical signals is of prime importance for their\napplications in future quantum and optical technologies. In a combined\nexperimental and theoretical study on exciton complexes in single semiconductor\nquantum dots we reveal a detailed picture of the dynamics employing three-beam\npolarization-resolved four-wave mixing (FWM) micro-spectroscopy. The\noscillatory dynamics of the FWM signals in the exciton-biexciton system is\ngoverned by the fine-structure splitting and the biexciton binding energy in an\nexcellent quantitative agreement between measurement and analytical\ndescription. The analysis of the excitation conditions exhibits a dependence of\nthe dynamics on the specific choice of polarization configuration, pulse areas\nand temporal ordering of driving fields. The interplay between the transitions\nin the four-level exciton system leads to rich evolution of coherence and\npopulation. Using two-dimensional FWM spectroscopy we elucidate the\nexciton-biexciton coupling and identify neutral and charged exciton complexes\nin a single quantum dot. Our investigations thus clearly reveal that FWM\nspectroscopy is a powerful tool to characterize spectral and dynamical\nproperties of single quantum structures.",
        "positive": "Ideal Chern bands are Landau levels in curved space: We prove that all the criteria proposed in the literature to identify a Chern\nband hosting exact fractional Chern insulating ground states, in fact, describe\nan equivalence with a lowest Landau level defined in curved space under a\nnon-uniform magnetic field. In addition, we design an operational test for the\nmost general instance of such lowest Landau level mapping, which only relies on\nthe computationally inexpensive evaluation of Bloch wavefunctions' derivatives.\nOur work clarifies the common origin of various Chern-idealness criteria,\nproves that these criteria exhaust all possible lowest Landau levels, and hints\nat classes of Chern bands that may posses interesting phases beyond Landau\nlevel physics."
    },
    {
        "anchor": "Kondo physics and orbital degeneracy interact to boost thermoelectrics\n  on the nanoscale: We investigate the transport through a nanoscale device consisting of a\ndegenerate double-orbital Anderson dot coupled to two uncorrelated leads. We\ndetermine the thermoelectric transport properties close to the one-electron\nregime and compare them to a corresponding single-orbital dot. The linear and\nnonlinear regimes are addressed, the latter via a non-equilibrium\ngeneralization of the non-crossing approximation based on the Keldysh\nformalism. Power output and efficiency in the Kondo regime are shown to be\nstrongly enhanced through the presence of a second orbital. We predict an\nexperimentally relevant optimal operating point which benefits from the\nconcomitant increase of the Kondo temperature in the two-orbital setup. An\napproximation based on the transport coefficients and fulfilling the\nthermodynamic balance is proven to remain appropriate even far beyond the\nexpected range of validity of such approaches. Finally, the double-orbital\nKondo regime reveals itself as a promising candidate to avoid, at least\npartially, the generic dilemma between optimal thermoelectric efficiency on one\nhand, and fair power output on the other.",
        "positive": "Orbital Hall effect and topology on a two-dimensional triangular\n  lattice: from bulk to edge: We investigate a generalized multi-orbital tight-binding model on a\ntriangular lattice, a system prevalent in a wide range of two-dimensional\nmaterials, and particularly relevant for simulating transition metal\ndichalcogenide monolayers. We show that the interplay between spin-orbit\ncoupling and different symmetry-breaking mechanisms leads to the emergence of\nfour distinct topological phases [Eck, P., \\textit{et al.}, Phys. Rev. B, 107\n(11), 115130 (2023)]. Remarkably, this interplay also triggers the orbital Hall\neffect with distinguished characteristics. Furthermore, by employing the\nLandauer-B\\\"uttiker formula, we establish that in the orbital Hall insulating\nphase, the orbital angular momentum is carried by edge states present in\nnanoribbons with specific terminations. We also show that, as expected, they do\nnot have topological protection against the disorder of the edge states\nbelonging to a first-order topological insulator."
    },
    {
        "anchor": "Strong exciton regulation of Raman scattering in monolayer\n  dichalcogenides: The weakly screened electron-hole interactions in an atomically thin\nsemiconductor not only downshift its excitation spectrum from a quasiparticle\none, but also redistribute excitation energies and wavefunction characters with\nprofound effects on diverse modes of material response, including the\nexciton-phonon scattering processes accessible to resonant Raman measurements.\nHere we develop a first-principles framework to calculate frequency-dependent\nresonant Raman intensities that includes excitonic effects and goes beyond the\nPlaczek approximation. We show how excitonic effects in MoS2 strongly regulate\nRaman scattering amplitudes and thereby explain the puzzling near-absence of\nresonant Raman response around the A and B excitons (which produce very strong\nsignals in optical absorption), and also the pronounced strength of the\nresonant Raman response from the C exciton. Furthermore, this efficient\nperturbative approach reduces the number of GW- BSE calculations from two per\nRaman mode (in finite displacement) to one for all modes and affords natural\nextension to higher-order resonant Raman processes.",
        "positive": "Quantum entropy evolution in the photovoltaic process of a quantum dot\n  photocell: For efficient photovoltaic conversion, it is important to understand how\nquantum entropy-related quantities evolve during the photovoltaic process. In\nthis study, using a double quantum dot (DQD) photocell model, we explored the\ndynamic quantum entropy-related parameters during the photovoltaic output. The\nfindings demonstrate that the dynamic photovoltaic performance is compatible\nwith quantum entropy-related parameters with varying tunneling coupling\nstrengths, but at varied ambient temperatures, an opposing relationship is\ndiscovered between them. Hence, some thermodynamic criteria may be used to\nevaluate the photovoltaic process in this proposed photocell model. This work's\nmerits include expanding our understanding of photoelectric conversion from a\nthermodynamic perspective as well as perhaps suggesting a new thermodynamic\napproach to efficient photoelectric conversion for DQD photocells."
    },
    {
        "anchor": "Negative Thermal expansion of pure and doped Graphene: Graphene and its derivatives distinguish themselves for their large negative\nthermal expansion even at temperatures as high as 1000K. The linear thermal\nexpansion coefficients (LTEC) of two-dimensional honeycomb structured pure\ngraphene and B/N doped graphene are analyzed using ab initio density functional\nperturbation theory (DFPT) employed in VASP software under quasiharmonic\napproximation. One of the essential ingredients required is the phonon\nfrequencies for a set of points in the Brillouin zone and their volume\ndependence. These were obtained from the dynamical matrix which was calculated\nusing VASP code in interface with phonopy code. In particular, the transverse\nacoustic modes (ZA) behave drastically differently as compared to planer modes\nand so also their volume dependence. Using this approach firstly thermal\nexpansion for pure graphene is calculated. The results agree with earlier\ncalculations using similar approach. Thereafter we have studied the effect of\nboron and nitrogen doping on LTEC. The LTEC of graphene is found to be negative\nin the entire range of temperature under study (0-1000K) and its value at room\ntemperature (RT) is around -3.26X10-6K-1. The value of LTEC at RT becomes more\nnegative with B/N doping in graphene. In order to get an insight into the cause\nof negative thermal expansion, we have computed the contribution of individual\nphonon modes of vibration. We notice that it is principally the ZA modes which\nare responsible for negative thermal expansion. It has been concluded that\ntransverse mode in 2D hexagonal lattices have an important role to play in many\nof the thermodynamical properties of 2D structures. We have extended the study\nto calculate the LTEC of h-BN sheet also.",
        "positive": "Floquet-engineered chiral-induced spin selectivity: The control of electron spin, which is crucial to the stability of matter,\noffers new possibilities for manipulating the properties of molecules and\nmaterials with potential applications in spintronics and chemical reactions.\nRecent experiments have demonstrated that electron transmission through chiral\nmolecules depends on the electron spin orientation, a phenomenon known as\nchiral-induced spin selectivity (CISS). In this study, we show that CISS can be\nobserved in achiral systems driven by an external circularly polarized laser\nfield in the framework of Floquet engineering. By using the Floquet theory for\na time-periodically driven system to investigate spin-dependent electron\ntransport in a two-terminal setup, we demonstrate that the spin polarization\ncan approach unity if the light intensity is sufficiently strong, the rate of\ndephasing is sufficiently small, and the average chemical potential of the two\nleads is within an appropriate range of values, which is narrow because of the\nhigh frequency of the laser field. To obtain a wider range of energies for\nlarge spin polarization, a combination of chiral molecules and light-matter\ninteractions is considered and the spin polarization of electrons transported\nthrough a helical molecule driven by a laser field is evaluated."
    },
    {
        "anchor": "Microwave-induced coupling of superconducting qubits: We investigate the quantum dynamics of a system of two coupled\nsuperconducting qubits under microwave irradiation. We find that, with the\nqubits operated at the charge co-degeneracy point, the quantum evolution of the\nsystem can be described by a new effective Hamiltonian which has the form of\ntwo coupled qubits with tunable coupling between them. This Hamiltonian can be\nused for experimental tests on macroscopic entanglement and for implementing\nquantum gates.",
        "positive": "Probing topological phase transitions via quantum reflection in the\n  graphene family materials: We theoretically investigate the quantum reflection of different atoms by\ntwo-dimensional (2D) materials of the graphene family (silicene, germanene, and\nstanene), subjected to an external electric field and circularly polarized\nlight. By using Lifshitz theory to compute the Casimir-Polder potential, which\nensures that our predictions apply to all regimes of atom-2D surface distances,\nwe demonstrate that the quantum reflection probability exhibits distinctive,\nunambiguous signatures of topological phase transitions that occur in 2D\nmaterials. We also show that the quantum reflection probability can be highly\ntunable by these external agents, depending on the atom-surface combination,\nreaching a variation of 40% for Rubidium in the presence of a stanene sheet.\nOur findings attest that not only dispersive forces play a crucial role in\nquantum reflection, but also that the topological phase transitions of the\ngraphene family materials can be comprehensively and efficiently probed via\natom-surface interactions at the nanoscale."
    },
    {
        "anchor": "High Responsivity in Molecular Beam Epitaxy (MBE) grown \\b{eta}-Ga2O3\n  Metal Semiconductor Metal (MSM) Solar Blind Deep-UV Photodetector: In this report, we demonstrate high spectral responsivity (SR) in MBE grown\nepitaxial \\b{eta}-Ga2O3-based solar blind MSM photodetectors (PD). (-2 0\n1)-oriented \\b{eta}-Ga2O3 thin film was grown by plasma-assisted MBE on c-plane\nsapphire substrates. MSM devices fabricated with Ni/Au contacts in an\ninterdigitated geometry were found to exhibit peak SR > 1.5 A/W at 236-240 nm\nat a bias of 4 V with a UV to visible rejection ratio > 105. The devices\nexhibited very low dark current < 10 nA at 20 V and showed no persistent\nphotoconductivity (PPC) as evident from the sharp transients with a\nphoto-to-dark current ratio > 103. These results represent the state-of-art\nperformance for MBE-grown \\b{eta}-Ga2O3 MSM solar blind detector.",
        "positive": "Quantum control of exciton wavefunctions in 2D semiconductors: Excitons -- bound electron-hole pairs -- play a central role in light-matter\ninteraction phenomena, and are crucial for wide-ranging applications from light\nharvesting and generation to quantum information processing. A long-standing\nchallenge in solid-state optics has been to achieve precise and scalable\ncontrol over the quantum mechanical state of excitons in semiconductor\nheterostructures. Here, we demonstrate a technique for creating tailored and\ntunable potential landscapes for optically active excitons in 2D semiconductors\nthat enables in-situ wavefunction shaping at the nanoscopic lengthscale. Using\nnanostructured gate electrodes, we create localized electrostatic traps for\nexcitons in diverse geometries such as quantum dots and rings, and arrays\nthereof. We show independent spectral tuning of multiple spatially separated\nquantum dots, which allows us to bring them to degeneracy despite material\ndisorder. Owing to the strong light-matter coupling of excitons in 2D\nsemiconductors, we observe unambiguous signatures of confined exciton\nwavefunctions in optical reflection and photoluminescence measurements. Our\nwork introduces a new approach to engineering exciton dynamics and interactions\nat the nanometer scale, with implications for novel optoelectronic devices,\ntopological photonics, and many-body quantum nonlinear optics."
    },
    {
        "anchor": "Domain wall statics and dynamics in nanowires with arbitrary\n  Dzyaloshinskii-Moriya tensors: The influence of different Dzyaloshinskii-Moriya interaction (DMI) tensor\ncomponents on the static and dynamic properties of domain walls (DWs) in\nmagnetic nanowires is investigated using one dimensional collective coordinates\nmodels and micromagnetic simulations. It is shown how the different\ncontributions of the DMI can be compactly treated by separating the symmetric\ntraceless, antisymmetric and diagonal components of the DMI tensor. First, we\ninvestigate the effect of all different DMI components on the static DW tilting\nin the presence and absence of in plane (IP) fields. We discuss the\npossibilities and limitations of this measurement approach for arbitrary DMI\ntensors. Secondly, the interplay of different DMI tensor components and their\neffect on the field driven dynamics of the DWs are studied and reveal a\nnon-trivial effect of the Walker breakdown field of the material. It is shown\nhow DMI tensors combining diagonal and off-diagonal elements can lead to a\nnon-linear enhancement of the Walker field, in contrast with the linear\nenhancement obtainable in the usual cases (interface DMI or bulk DMI).",
        "positive": "Heat transport in disordered quantum harmonic oscillator chains: We study heat conduction in quantum disordered harmonic chains connected to\ngeneral heat reservoirs which are modeled as infinite collection of\noscillators. Formal exact expressions for the thermal current are obtained and\nit is shown that, in some special cases, they reduce to Landauer-like forms.\nThe asymptotic system size dependence of the current is analysed and is found\nto be similar to the classical case. It is a power law dependence and the power\ndepends on the spectral properties of the reservoirs."
    },
    {
        "anchor": "Observation of multi-directional energy transfer in a hybrid\n  plasmonic-excitonic nanostructure: Hybrid plasmonic devices involve a nanostructured metal supporting localized\nsurface plasmons to amplify light-matter interaction, and a non-plasmonic\nmaterial to functionalize charge excitations. Application-relevant epitaxial\nheterostructures, however, give rise to ballistic ultrafast dynamics that\nchallenge the conventional semiclassical understanding of unidirectional\nnanometal-to-substrate energy transfer. We study epitaxial Au nanoislands on\nWSe$_2$ with time- and angle-resolved photoemission spectroscopy and\nfemtosecond electron diffraction: this combination of techniques resolves\nmaterial, energy and momentum of charge-carriers and phonons excited in the\nheterostructure. We observe a strong non-linear plasmon-exciton interaction\nthat transfers the energy of sub-bandgap photons very efficiently to the\nsemiconductor, leaving the metal cold until non-radiative exciton recombination\nheats the nanoparticles on hundreds of femtoseconds timescales. Our results\nresolve a multi-directional energy exchange on timescales shorter than the\nelectronic thermalization of the nanometal. Electron-phonon coupling and\ndiffusive charge-transfer determine the subsequent energy flow. This complex\ndynamics opens perspectives for optoelectronic and photocatalytic applications,\nwhile providing a constraining experimental testbed for state-of-the-art\nmodelling.",
        "positive": "Vibrational cooling, heating, and instability in molecular conducting\n  junctions: Full counting statistics analysis: We study current-induced vibrational cooling, heating, and instability in a\ndonor-acceptor rectifying molecular junction using a full counting statistics\napproach. In our model, electron-hole pair excitations are coupled to a given\nmolecular vibrational mode which is either harmonic or highly anharmonic. This\nmode may be further coupled to a dissipative thermal environment. Adopting a\nmaster equation approach, we confirm the charge and heat exchange fluctuation\ntheorem in the steady-state limit, for both harmonic and anharmonic models.\nUsing simple analytical expressions, we calculate the charge current and\nseveral measures for the mode effective temperature. At low bias, we observe\nthe effect of bias-induced cooling of the vibrational mode. At higher bias, the\nmode effective temperature is higher than the environmental temperature, yet\nthe junction is stable. Beyond that, once the vibrational mode (bias-induced)\nexcitation rate overcomes its relaxation rate, instability occurs. We identify\nregimes of instability as a function of voltage bias and coupling to an\nadditional phononic thermal bath. Interestingly, we observe a reentrant\nbehavior where an unstable junction can properly behave at a high enough bias.\nThe mechanism for this behavior is discussed."
    },
    {
        "anchor": "Spin-dependent Seebeck coefficients of Ni_{80}Fe_{20} and Co in\n  nanopillar spin valves: We have experimentally determined the spin-dependent Seebeck coefficient of\npermalloy (Ni_{80}Fe_{20}) and cobalt (Co) using nanopillar spin valve devices.\nThe devices were specifically designed to completely separate heat related\neffects from charge related effects. A pure heat current through the nanopillar\nspin valve, a stack of two ferromagnetic layers (F) separated by a non-magnetic\nlayer (N), leads to a thermovoltage proportional to the spin-dependent Seebeck\ncoefficient S_{S}=S_{\\uparrow}-S_{\\downarrow} of the ferromagnet, where\nS_{\\uparrow} and S_{\\downarrow} are the Seebeck coefficient for spin-up and\nspin-down electrons. By using a three-dimensional finite-element model (3D-FEM)\nbased on spin-dependent thermoelectric theory, whose input material parameters\nwere measured in separate devices, we were able to accurately determine a\nspin-dependent Seebeck coefficient of -1.8 microvolt/Kelvin and -4.5\nmicrovolt/Kelvin for cobalt and permalloy, respectively corresponding to a\nSeebeck coefficient polarization P_{S}=S_{S}/S_{F} of 0.08 and 0.25, where\nS_{F} is the Seebeck coefficient of the ferromagnet. The results are in\nagreement with earlier theoretical work in Co/Cu multilayers and spin-dependent\nSeebeck and spin-dependent Peltier measurements in Ni_{80}Fe_{20}/Cu spin valve\nstructures.",
        "positive": "Aharonov-Casher effect in a two dimensional hole gas with spin-orbit\n  interaction: We study the quantum interference effects induced by the Aharonov-Casher\nphase in a ring structure in a two-dimensional heavy hole (HH) system with\nspin-orbit interaction realizable in narrow asymmetric quantum wells. The\ninfluence of the spin-orbit interaction strength on the transport is\ninvestigated analytically. These analytical results allow us to explain the\ninterference effects as a signature of the Aharonov-Casher Berry phases. Unlike\nprevious studies on the electron two-dimensional Rashba systems, we find that\nthe frequency of conductance modulations as a function of the spin-orbit\nstrength is not constant but increases for larger spin-orbit splittings. In the\nlimit of thin channel rings (width smaller than Fermi wavelength), we find that\nthe spin-orbit splitting can be greatly increased due to quantization in the\nradial direction. We also study the influence of magnetic field considering\nboth limits of small and large Zeeman splittings."
    },
    {
        "anchor": "Dynamics and decoherence in nonideal Thouless quantum motors: Different proposals for adiabatic quantum motors (AQMs) driven by DC currents\nhave recently attracted considerable interest. However, the systems studied are\noften based on simplified models with highly ideal conditions where the\nenvironment is neglected. Here, we investigate the performance (dynamics,\nefficiency, and output power) of a prototypical AQM, the Thouless motor. To\ninclude the effect of the surroundings on this type of AQMs, we extended our\nprevious theory of decoherence in current-induced forces (CIFs) to account for\nspatially distributed decoherent processes. We provide analytical expressions\nthat account for decoherence in CIFs, friction coefficients and the\nself-correlation functions of the CIFs. We prove that the model is\nthermodynamically consistent and we find that decoherence drastically reduces\nthe efficiency of the motor mainly due to the increase in conductance, while\nits effect on the output power is not much relevant. The effect of decoherence\non the current-induced friction depends on the length of the system, reducing\nthe friction for small systems while increasing it for long ones. Finally, we\nfind that reflections of the electrons at the boundary of the system induce\nadditional conservative forces that affect the dynamics of the motor. In\nparticular, this results in the hysteresis of the system and a voltage\ndependent switching.",
        "positive": "Absence of ferromagnetism in VSe$_2$ caused by its charge density wave\n  phase: How magnetism emerges in low-dimensional materials such as transition metal\ndichalcogenides at the monolayer limit is still an open question. Herein, we\npresent a comprehensive study of the magnetic properties of single crystal and\nmonolayer VSe$_{2}$, both experimentally and \\emph{ab initio}. Magnetometry,\nX-ray magnetic circular dichrosim (XMCD) and \\emph{ab initio} calculations\ndemonstrate that the charge density wave in bulk stoichiometric VSe$_{2.0}$\ncauses a structural distortion with a strong reduction in the density of sates\nat the Fermi level, prompting the system towards a non-magnetic state but on\nthe verge of a ferromagnetic instability. In the monolayer limit, the\nstructural rearrangement induces a Peierls distortion with the opening of an\nenergy gap at the Fermi level and the absence of magnetic order. Control\nexperiments on defect-induced VSe$_{2-\\delta}$ single crystals show a breakdown\nof magnetism, discarding vacancies as a possible origin of magnetic order in\nVSe$_{2}$."
    },
    {
        "anchor": "Atomistic mechanism of carbon nanotube cutting catalyzed by nickel under\n  the electron beam: The cutting of single-walled carbon nanotubes by an 80 keV electron beam\ncatalyzed by nickel clusters is imaged in situ using aberration-corrected\nhigh-resolution transmission electron microscopy. Extensive molecular dynamics\nsimulations within the CompuTEM approach provide insight into the mechanism of\nthis process and demonstrate that the combination of irradiation and nickel\ncatalyst is crucial for the cutting process to take place. The atomistic\nmechanism of cutting is revealed by detailed analysis of irradiation-induced\nreactions of bonds reorganization and atom ejection in the vicinity of the\nnickel cluster, showing a highly complex interplay of different chemical\ntransformations catalysed by the metal cluster. One of the most prevalent\npathways includes three consecutive stages: formation of polyyne carbon chains\nfrom carbon nanotube, dissociation of the carbon chains into single and pairs\nof adatoms adsorbed on the nickel cluster, and ejection of these adatoms\nleading to the cutting of nanotube. Significant variations in the atom ejection\nrate are discovered depending on the process stage and nanotube diameter. The\nrevealed mechanism and kinetic characteristics of cutting process provide\nfundamental knowledge for the development of new methodologies for control and\nmanipulation of carbon structures at the nanoscale.",
        "positive": "Transmission spectra of bistable systems: from ultra-quantum to\n  classical regime: We present an analytical and numerical study of the fluorescence spectra of a\nbistable driven system by means of Keldysh diagram technique in\npseudo--particle representation. The spectra exhibit smooth transition between\nultra-quantum and the quasiclassical limits and indicate the threshold value of\nthe external field when changing of the most probable stable state occurs. The\nanalysis of the fluorescence spectra also allows to determine the most probable\nstable state of the system. It was also shown that at integer and half-integer\ndetuning-nonlinearity ratio multiphoton resonance leads to abrupt changes in\nfluorescence spectra. It was also revealed that the fluorescence spectra are\nsymmetric in the limit of zero environment temperature. The predicted features\nof the spectra could be observed in experiments with ultra-high quality\nresonators in either microwave or optical domain."
    },
    {
        "anchor": "Intrinsic spin-Hall accumulation in honeycomb lattices: Band structure\n  effects: Local spin and charge densities on a two-dimensional honeycomb lattice are\ncalculated by the Landauer-Keldysh formalism (LKF). Through the empirical\ntight-binding method, we show how the realistic band structure can be brought\ninto the LKF. Taking the Bi(111) surface, on which strong surface states and\nRashba spin-orbit coupling are present [Phys. Rev. Lett. 93, 046403 (2004)], as\na numeric example, we show typical intrinsic spin-Hall accumulation (ISHA)\npatterns thereon. The Fermi-energy-dependence of the spin and charge transport\nin two-terminal nanostructure samples is subsequently analyzed. By changing\nE_{F}, we show that the ISHA pattern is nearly isotropic (free-electron-like)\nonly when E_{F} is close to the band bottom, and is sensitive/insensitive to\nE_{F} for the low/high bias regime with such E_{F}. With E_{F} far from the\nband bottom, band structure effects thus enter the ISHA patterns and the\ntransport direction becomes significant.",
        "positive": "Rectification by charging -- the physics of contact-induced current\n  asymmetry in molecular conductors: We outline the qualitatively different physics behind charging-induced\ncurrent asymmetries in molecular conductors operating in the weakly interacting\nself-consistent field (SCF) and the strongly interacting Coulomb Blockade (CB)\nregimes. A conductance asymmetry arises in SCF because of the unequal\nmean-field potentials that shift a closed-shell conducting level differently\nfor positive and negative bias. A very different current asymmetry arises for\nCB due to the unequal number of open-shell excitation channels at opposite bias\nvoltages. The CB regime, dominated by single charge effects, typically requires\na computationally demanding many-electron or Fock space description. However,\nour analysis of molecular Coulomb Blockade measurements reveals that many novel\nsignatures can be explained using a {{simpler}} orthodox model that involves an\nincoherent sum of Fock space excitations and {\\it{hence treats the molecule as\na metallic dot or an island}}. This also reduces the complexity of the Fock\nspace description by just including various charge configurations only, thus\npartially underscoring the importance of electronic structure, while retaining\nthe essence of the single charge nature of the transport process. We finally\npoint out, however, that the inclusion of electronic structure and hence\nwell-resolved Fock space excitations is crucial in some notable examples."
    },
    {
        "anchor": "Charge density wave surface phase slips and non-contact nanofriction: Bulk electrical dissipation caused by charge-density-wave (CDW) depinning and\nsliding is a classic subject. We present a novel local, nanoscale mechanism\ndescribing the occurrence of mechanical dissipation peaks in the dynamics of an\natomic force microscope tip oscillating above the surface of a CDW material.\nLocal surface 2$\\pi$ slips of the CDW phase are predicted to take place giving\nrise to mechanical hysteresis and large dissipation at discrete tip surface\ndistances. The results of our static and dynamic numerical simulations are\nbelieved to be relevant to recent experiments on NbSe$_2$; other candidate\nsystems in which similar effects should be observable are also discussed.",
        "positive": "Electron Transmission through Modified Benzene: The renormalization method is applied to investigate the electron\ntransmission properties of a circuit containing a benzene molecule, in which\none of the carbon atoms has been modified so as to simulate displacement in\nposition or replacement by another atom. Consideration of the different\npossible attachments of the leads, and the relative location of the modified\natom, results in 9 distinct configurations to examine. For each configuration,\nthe number and locations of anti-resonances, and whether they shift upon\nvariation of the parameters, is seen to be the key to determining the shape of\nthe electron-transmission curve. In particular, those configurations, in which\nthe perturbed atom is not directly attached to a lead, are seen to have the\nmost variation in their structure, compared to pure benzene."
    },
    {
        "anchor": "Resonant Cooling of Nuclear Spins in Quantum Dots: We propose to use the spin-blockade regime in double quantum dots to reduce\nnuclear spin polarization fluctuations in analogy with optical Doppler cooling.\nThe Overhauser shift brings electron levels in and out of resonance, creating\nfeedback to suppress fluctuations. Coupling to the disordered nuclear spin\nbackground is a major source of noise and dephasing in electron spin\nmeasurements in such systems. Estimates indicate that a better than 10-fold\nreduction of fluctuations is possible.",
        "positive": "Skyrmion spin transfer torque due to current confined in a nanowire: In this work we compute the torque field present in a ferromagnet in contact\nwith a metallic nanowire when a skyrmion is present. If the nanowire is narrow\nenough the current is carried by a single conduction band. In this regime the\nclassical torque model breaks down and we show that a skyrmion driven by spin\ntransfer torque moves in a different direction than predicted by the classical\nmodel. However, the amount of charge current required to move a skyrmion with a\ncertain velocity in the single band regime is similar to a classical model of\ntorque where it is implicitly assumed current transport by many conduction\nbands. The single band regime is more efficient creating spin current from\ncharge current because of the perfect polarization of the single band but is\nless efficient creating torque from spin current. Nevertheless, it is possible\nto take profit of the single band regime to move skyrmions even with no net\ncharge or spin current flowing between the device contacts. We have also been\nable to recover the classical limit considering an ensemble of only a few\nelectronic states. In this limit we have discovered that electron diffusion\nneeds to be considered even in ballistic nanowires due the effect of the\nskyrmion structure on the electron current."
    },
    {
        "anchor": "Electronic and spectral properties of Ge1-xSnx quantum dots: an\n  atomistic study: In this paper, we study theoretically the electron and spectral properties of\nGe1-xSnx systems, including alloys, cubic- and spherical quantum dots. The\nsingle-particle electron and hole states are calculated within the sp3d5s*\ntight-binding approach and used in further modeling of the optical properties.\nWe systematically study the interplay of Sn-driven indirect-direct band-gap\ntransition and the quantum confinement effect in systems of reduced\ndimensionality. We demonstrate the regime of sizes and composition, where the\nground state in Ge1-xSnx quantum dot is optically active. Finally, we calculate\nabsorbance spectra in experimentally-relevant colloidal quantum dots and\ndemonstrate a satisfactory agreement with experimental data.",
        "positive": "Evidence of trion-libron coupling in chirally adsorbed single molecules: Interplay between motion of nuclei and excited electrons in molecules plays a\nkey role both in biological and artificial nanomachines. Here we provide a\ndetailed analysis of coupling between quantized librational modes (librons) and\ncharged excited states (trions) on single phthalocyanine dyes adsorbed on a\nsurface. By means of tunnelling electron-induced electroluminescence, we\nidentify libronic progressions on a {\\mu}eV energy range in spectra of chirally\nadsorbed phthalocyanines, which are otherwise absent from spectra of\nsymmetrically adsorbed species. Experimentally measured libronic spectra match\nvery well the theoretically calculated libron eigenenergies and peak\nintensities (Franck-Condon factors) and reveal an unexpected depopulation\nchannel for the zero libron of the excited state that can be effectively\ncontrolled by tuning the size of the nanocavity. Our results showcase the\npossibility of characterizing the dynamics of molecules by their low-energy\nmolecular modes using {\\mu}eV-resolved tip-enhanced spectroscopy."
    },
    {
        "anchor": "Accidental degeneracy of double Dirac cones in a phononic crystal: Artificial honeycomb lattices with Dirac cone dispersion provide a\nmacroscopic platform to study the massless Dirac quasiparticles and their novel\ngeometric phases. In this paper, a quadruple-degenerate state is achieved at\nthe center of Brillouin zone (BZ) in a two-dimensional honeycomb lattice\nphononic crystal, which is a result of accidental degeneracy of two\ndouble-degenerate states. In the vicinity of the quadruple-degenerate state,\nthe dispersion relation is linear. Such quadruple degeneracy is analyzed by\nrigorous representation theory of groups. Using method, a reduced Hamiltonian\nis obtained to describe the linear Dirac dispersion relations of such\nquadruple-degenerate state, which is well consistent with the simulation\nresults. Near such accidental degeneracy, we observe some unique wave\npropagating properties, such as defect insensitive propagating character and\nTalbot effect.",
        "positive": "Ultrafast laser interaction with transparent multi-layer SiO2/Si3N4\n  films: We investigate the use of ultrafast lasers exposure to induce localized\ncrystallization and elemental redistribution in amorphous dielectric\nmulti-layers, composed of alternating Si3N4and SiO2layers of sub-micron\nthickness. Specifically,we report on the occurrence of a laser-induced\nelemental intermixing process and on the presence of silicon nanocrystals\nclusters localized within the multi-layers structure. The spatial distribution\nof these clusters goes significantly beyond the zone under direct laser\nexposure providing evidences of energy being channeled transversely to the\nlaser propagation axis at the interface of the nanoscale layers. Thanks to the\nextreme conditions reigning during laser exposure, this process transposed to\nvarious materials may offer a pathway for local and selective crystallization\nof a variety of compounds and phases, difficult to obtain otherwise."
    },
    {
        "anchor": "Electrostatically actuated silicon-based nanomechanical switch at room\n  temperature: We demonstrate a silicon-based high frequency nanomechanical device capable\nof switching controllably between two states at room temperature. The device\nuses a nanomechanical resonator with two distinct states in the hysteretic\nnonlinear regime. In contrast to prior work, we demonstrate room temperature\nelectrostatic actuation and sensing of the switching device with 100% fidelity\nby phase modulating the drive signal. This phase-modulated device can be used\nas a low-power high-speed mechanical switch integrated on-chip with silicon\ncircuitry.",
        "positive": "Half-filled 2D bilayers in a strong magnetic field: Revisiting the\n  $\u03bd=1/2$ fractional quantum Hall effect: We examine the quantum phase diagram of the fractional quantum Hall effect in\nthe lowest Landau level in half-filled bilayer structures as a function of\ntunneling strength and layer separation. Using numerical exact diagonalization\nwe investigate the important question of whether this system supports a\nfractional quantum Hall effect described by the non-Abelian Moore-Read Pfaffian\nstate in the strong tunneling regime. We find that, although it is in principle\npossible, it is unlikely that the non-Abelian FQHE exists in the lowest Landau\nlevel. We establish that all so far observed FQHE states in half-filled lowest\nLandau level bilayers are most likely described by the Abelian Halperin 331\nstate."
    },
    {
        "anchor": "Advantages of using YBCO-Nanowire-YBCO heterostructures in the search\n  for Majorana Fermions: We propose an alternative platform to observe Majorana bound states in solid\nstate systems. High critical temperature cuprate superconductors can induce\nsuperconductivity, by proximity effect, in quasi one dimensional nanowires with\nstrong spin orbit coupling. They favor a wider and more robust range of\nconditions to stabilize Majorana fermions due to the large gap values, and\noffer novel functionalities in the design of the experiments determined by\ndifferent dispersion for Andreev bound states as a function of the phase\ndifference.",
        "positive": "Non-Kramers degeneracy and oscillatory tunnel splittings in the biaxial\n  Spin System: We have investigated analytically quantum tunneling of large spin in the\nbiaxial spin system with the magnetic field applied along the hard and medium\nanisotropy axes by using a purely quantum-mechanical approach. When the\nmagnetic field parallels the hard axis, the tunnel splittings of all the energy\nlevel pairs are oscillatory as a function of the magnetic field. The quenching\npoints are completely determined by the coexistence of solutions of the Ince's\nequation. When the magnetic field points the medium axis, the tunnel splitting\noscillations disappear due to no coexistence of solutions. These results\ncoincide the recent experimental observations in the nanomagnet Fe$_8$."
    },
    {
        "anchor": "Valley depolarization due to inter- and intra-valley electron-hole\n  exchange interactions in monolayer MoS$_{2}$: We investigate the valley depolarization due to the electron-hole exchange\ninteraction in monolayer MoS$_{2}$. Both the long- and short-range parts of the\nintra- and inter-valley electron-hole exchange interactions are calculated. We\nfind that both the long- and short-range exchange interactions can cause the\ninter- and intra-valley bright exciton transitions. With the intra-valley\nbright exciton transition channel nearly forbidden due to the large splitting\nof the valence bands, the inter-valley channel due to the exchange interaction\ncan cause the valley depolarization efficiently by the Maialle-Silva-Sham\nmechanism [Phys. Rev. B {\\bf 47}, 15776 (1993)]. With only the long-range\nexchange interaction, the calculations show good agreement with the recent\nvalley polarization experiments, including the time-resolved valley\npolarization measurement, the pump-probe experiment and the steady-state PL\npolarization measurement. We further show that for the A-exciton with large\n(small) center-of-mass momentum, the long-range exchange interaction can cause\nthe {\\em fast} ({\\em slow}) inter-valley exciton transition.",
        "positive": "Quantum control of topological defects in magnetic systems: Energy-efficient classical information processing and storage based on\ntopological defects in magnetic systems have been studied over past decade. In\nthis work, we introduce a class of macroscopic quantum devices in which a\nquantum state is stored in a topological defect of a magnetic insulator. We\npropose non-invasive methods to coherently control and readout the quantum\nstate using ac magnetic fields and magnetic force microscopy, respectively.\nThis macroscopic quantum spintronic device realizes the magnetic analog of the\nthree-level rf-SQUID qubit and is built fully out of electrical insulators with\nno mobile electrons, thus eliminating decoherence due to the coupling of the\nquantum variable to an electronic continuum and energy dissipation due to Joule\nheating. For a domain wall sizes of $10-100$~nm and reasonable material\nparameters, we estimate qubit operating temperatures in the range of $0.1-1$~K,\na decoherence time of about $0.01-1$~$\\mu$s, and the number of Rabi flops\nwithin the coherence time scale in the range of $10^{2}-10^{4}$."
    },
    {
        "anchor": "Cross effect of magnetic field and charge current on antiferromagnetic\n  dynamics: We theoretically examine a cross effect of magnetic field and charge current\non antiferromagnetic domain wall dynamics. Since antiferromagnetic materials\nare largely insensitive to external magnetic fields in general, charge current\nhas been shown recently as an alternative and efficient way to manipulate\nantiferromagnets. We find a new role of the magnetic field in the\nantiferromagnetic dynamics that appears when it is combined with charge\ncurrent, demonstrating a domain wall motion in the presence of both field and\ncurrent. We show that a spatially-varying magnetic field can shift the\ncurrent-driven domain-wall velocity, depending on the domain-wall structure and\nthe direction of the field-gradient. Our result suggests a novel concept of\nfield-control of current-driven antiferromagnetic dynamics.",
        "positive": "Strategy for accurate thermal biasing at the nanoscale: We analyze the benefits and shortcomings of a thermal control in nanoscale\nelectronic conductors by means of the contact heating scheme. Ideally, this\nstraightforward approach allows one to apply a known thermal bias across\nnanostructures directly through metallic leads, avoiding conventional substrate\nintermediation. We show, by using the average noise thermometry and local noise\nsensing technique in InAs nanowire based devices, that a nanoscale metallic\nconstriction on a SiO2 substrate acts like a diffusive conductor with\nnegligible electron-phonon relaxation and non-ideal leads. The non-universal\nimpact of the leads on the achieved thermal bias -- which depends on their\ndimensions, shape and material composition -- is hard to minimize, but is\npossible to accurately calibrate in a properly designed nano-device. Our\nresults allow to reduce the issue of the thermal bias calibration to the\nknowledge of the heater resistance and pave the way for accurate thermoelectric\nor similar measurements at the nanoscale."
    },
    {
        "anchor": "Pulsed photoelectric coherent manipulation and detection of NV centre\n  spins in diamond: Hybrid photoelectric detection of NV magnetic resonances (PDMR) is\nanticipated to lead to scalable quantum chip technology. To achieve this goal,\nit is crucial to prove that PDMR readout is compatible with the coherent spin\ncontrol. Here we present PDMR MW pulse protocols that filter background\ncurrents related to ionization of NS0 defects and achieve a high contrast and\nS/N ratio. We demonstrate Rabi and Ramsey protocols on shallow\nnitrogen-implanted electronic grade diamond and the coherent readout of ~ 5 NV\nspins, as a first step towards the fabrication of scalable photoelectric\nquantum devices.",
        "positive": "Electronic structure of CdTe nanocrystals: A tight-binding study: We present a symmetry-based calculation of the electronic structure of a\ncompound semiconductor quantum dot (QD) in the sp^3s* tight-binding model\nincluding the spin-orbit interaction. The Hamiltonian matrix is diagonalized\nexactly for CdTe QD sizes up to 60 {\\AA}. The surface dangling bonds are\npassivated by hydrogen through a careful analysis of the density of states and\nwave functions. The calculated size dependence of the energy gap shows a\nreasonable agreement with the available experimental data. Our symmetry\nanalysis indicates that, in contrast with a reported prediction of the\nthree-band effective-mass model, the fundamental interband transition remains\ndipole-allowed in CdTe nanocrystals."
    },
    {
        "anchor": "Combined impact of entropy and carrier delocalization on charge transfer\n  exciton dissociation at the donor-acceptor interface: Several models of the charge transfer exciton (CTE) have been proposed to\nexplain its dissociation at the donor-acceptor (DA) interface. However, the\nunderlying physics is still under debate. Here, we derive temperature\n($T$)-dependent tight-binding model for an electron-hole pair at the DA\ninterface. The main finding is the existence of the localization-delocalization\ntransition at a critical $T$, which can explain the CTE dissociation. The\npresent study highlights the combined effect of entropy (finite-$T$) and\ncarrier delocalization in the CTE dissociation.",
        "positive": "Localized Distributions of Quasi Two-Dimensional Electronic States near\n  Defects Artificially Created at Graphite Surfaces in Magnetic Fields: We measured the local density of states of a quasi two-dimensional electron\nsystem (2DES) near defects, artificially created by Ar-ion sputtering, on\nsurfaces of highly oriented pyrolytic graphite (HOPG) with scanning tunneling\nspectroscopy (STS) in high magnetic fields. At valley energies of the Landau\nlevel spectrum, we found two typical localized distributions of the 2DES\ndepending on the defects. These are new types of distributions which are not\nobserved in the previous STS work at the HOPG surface near a point defect [Y.\nNiimi \\textit{et al}., Phys. Rev. Lett. {\\bf 97}, 236804 (2006).]. With\nincreasing energy, we observed gradual transformation from the localized\ndistributions to the extended ones as expected for the integer quantum Hall\nstate. We show that the defect potential depth is responsible for the two\nlocalized distributions from comparison with theoretical calculations."
    },
    {
        "anchor": "Back-action supercurrent diodes: Back-action refers to a response that retro-acts on a system to tailor its\nproperties with respect to an external stimulus. This self-induced effect\ngenerally belongs to both the natural and technological realm, ranging from\nneural networks to optics and electronic circuitry. In electronics, back-action\nmechanisms are at the heart of many classes of devices such as amplifiers,\noscillators, and sensors. Here, we demonstrate that back-action can be\nsuccessfully exploited to achieve $\\textit{non-reciprocal}$ transport in\nsuperconducting circuits. Our device realizes a supercurrent diode, since the\ndissipationless current flows in one direction whereas dissipative transport\noccurs in the opposite direction. Supercurrent diodes presented so far rely on\nmagnetic elements or vortices to mediate charge transport or external magnetic\nfields to break time-reversal symmetry. In our implementation, back-action\nsolely turns a conventional reciprocal superconducting weak link with no\nasymmetry between the current bias directions into a diode, where the critical\ncurrent amplitude depends on the bias sign. The self-interaction of the\nsupercurrent with the device stems from the gate tunability of the critical\ncurrent, which uniquely promotes up to $\\sim$88% of magnetic field-free signal\nrectification and diode functionality with selectable polarity. The concept we\nintroduce is very general and can be applied directly to a large variety of\ndevices, thereby opening novel functionalities in superconducting electronics.",
        "positive": "Low offset frequency $1/f$ flicker noise in spin torque vortex\n  oscillators: Low frequency noise close to the carrier remains little explored in spin\ntorque nano oscillators. However, it is crucial to investigate as it limits the\noscillator's frequency stability. This work addresses the low offset frequency\nflicker noise of a TMR-based spin-torque vortex oscillator in the regime of\nlarge amplitude steady oscillations. We first phenomenologically expand the\nnonlinear auto-oscillator theory aiming to reveal the properties of this noise.\nWe then present a thorough experimental study of the oscillator's $1/f$ flicker\nnoise and discuss the results based on the theoretical predictions. Hereby, we\nconnect the oscillator's nonlinear dynamics with the concept of flicker noise\nand furthermore refer to the influence of a standard $1/f$ noise description\nbased on the Hooge formula, taking into account the non-constant magnetic\noscillation volume, which contributes to the magnetoresistance."
    },
    {
        "anchor": "Theory of Edge States in Systems with Rashba Spin-Orbit Coupling: We study the edge states in a two dimensional electron gas with a transverse\nmagnetic field and Rashba spin-orbit coupling. In the bulk, the interplay\nbetween the external field perpendicular to the gas plane and the spin-orbit\ncoupling leads to two branches of states that, within the same energy window,\nhave different cyclotron radii. For the edge states, surface reflection\ngenerates hybrid states with the two cyclotron radii. We analyze the spectrum\nand spin structure of these states and present a semiclassical picture of them.",
        "positive": "Electronic Green's functions in a T-shaped multi-quantum dot system: We developed a set of equations to calculate the electronic Green's functions\nin a T-shaped multi-quantum dot system using the equation of motion method. We\nmodel the system using a generalized Anderson Hamiltonian which accounts for\n{\\em finite} intradot on-site Coulomb interaction in all component dots as well\nas for the interdot electron tunneling between adjacent quantum dots. Our\nresults are obtained within and beyond the Hartree-Fock approximation and\nprovide a path to evaluate all the electronic correlations in the multi-quantum\ndot system in the Coulomb blockade regime. Both approximations provide\ninformation on the physical effects related to the finite intradot on-site\nCoulomb interaction. As a particular example for our generalized results, we\nconsidered the simplest T-shaped system consisting of two dots and proved that\nour approximation introduces important corrections in the detector and side\ndots Green's functions, and implicitly in the evaluation of the system's\ntransport properties. The multi-quantum dot T-shaped setup may be of interest\nfor the practical realization of qubit states in quantum dots systems."
    },
    {
        "anchor": "Photostimulated desorption of Xe from Au(001) surfaces via transient Xe-\n  formation: Photo-stimulated desorption (PSD) of Xe atoms from the Au(001) surface in\nthermal and nonthermal regimes was investigated by the time-of-flight\nmeasurement at photon energies of 6.4 and 2.3 eV. Xe was desorbed in a thermal\nway at high laser fluence, which was in good agreement with theoretical\nsimulations. At a low laser fluence, on the other hand, desorption was induced\nonly at a photon energy of 6.4 eV by a non-thermal one-photon process. We argue\nthat the nonthermal PSD occurs via transient formation of Xe- on Au(001). The\nlifetime of Xe- is estimated to be ~15 fs with a classical model calculation.\nWhereas the electron affinity of Xe is negative in the isolated state, it is\nstabilized by the metal proximity effect.",
        "positive": "Fractional Exclusion Statistics and the Universal Quantum of Thermal\n  Conductance: A Unifying Approach: We introduce a generalized approach to one-dimensional (1D) conduction based\non Haldane's concept of fractional statistics (FES) and the Landauer\nformulation of transport theory. We show that the 1D ballistic thermal\nconductance is independent of the statistics obeyed by the carriers and is\ngoverned by the universal quantum $ (\\pi^2 k^2_B T)/(3h) $ in the degenerate\nregime. By contrast, the electrical conductance of FES systems is\nstatistics-dependent. This work unifies previous theories of electron and\nphonon systems and explains an interesting commonality in their behavior."
    },
    {
        "anchor": "ac-locking of thermally-induced sine-Gordon breathers: A complete framework for exciting and detecting thermally-induced, stabilized\nsine-Gordon breathers in ac-driven long Josephson junctions is developed. The\nformation of long-time stable breathers locked to the ac source occurs for a\nsufficiently high temperature. The latter emerges as a powerful control\nparameter, allowing for the remarkably stable localized modes to appear.\nNonmonotonic behaviors of both the breather generation probability and the\nenergy spatial correlations versus the thermal noise strength are found. The\njunction's resistive switching characteristics provides a clear experimental\nsignature of the breather.",
        "positive": "Nanoscale Phase Separation in Ferroelectric Materials: Many materials exhibit nanoscale phase separation, when inside the host\nthermodynamic phase there arise nanosize embryos of another thermodynamic\nphase. A prominent example of this phenomenon is provided by ferroelectric\nmaterials. The theoretical description of such phase heterogeneous materials is\nquite challenging, since they are essentially nonuniform, the nonuniformity is\nrandom, and often they are quasiequilibrium, but not absolutely equilibrium. An\napproach is suggested for the theoretical description of phase separated\nferroelectrics, consisting of a ferroelectric matrix with nanoscale\nparaelectric inclusions. The properties of the heterophase ferroelectrics are\nstudied."
    },
    {
        "anchor": "On the Long-Range Exciton Transport in H-Aggregated Heterotriangulene\n  Chains: Self-assembled aggregates of pigment molecules are potential building blocks\nfor excitonic circuits that find their application in energy conversion and\noptical signal processing. Recent experimental studies of one-dimensional\nheterotriangulene supramolecular aggregates suggested that singlet excitons in\nthese structures can propagate on several micron distances. We explore this\npossibility theoretically by combining electronic structure calculations with\nmicroscopic models for exciton transport. Detailed characterization of the\nstructural disorder and exciton decoherence is provided. We argue that\nconventional exciton transport models give about an order of magnitude shorter\nestimates for the exciton propagation length which suggest that there are other\npossible explanations of the experimental results.",
        "positive": "Analysis of contact stiffness in Ultrasound Atomic Force Microscopy:\n  Three-dimensional time-dependent ultrasound modeling: Ultrasound Atomic Force Microscopy (US-AFM) has been used for subsurface\nimaging of nanostructures. The contact stiffness variations have been suggested\nas the origin of the image contrast. Therefore, to analyze the image contrast,\nthe local changes in the contact stiffness due to the presence of subsurface\nfeatures should be calculated. So far, only static simulations have been\nconducted to analyze the local changes in the contact stiffness and,\nconsequently, the contrast in US-AFM. Such a static approach does not fully\nrepresent the real US-AFM experiment, where an ultrasound wave is launched\neither into the sample or at the tip, which modulates the contact stiffness.\nThis is a time-dependent nonlinear dynamic problem rather than a static and\nstationary one. This letter presents dynamic 3D ultrasound analysis of contact\nstiffness in US-AFM (in contrast to static analysis) to realistically predict\nthe changes in contact stiffness and thus the changes in the subsurface image\ncontrast. The modulation frequency also influences the contact stiffness\nvariations and, thus, the image contrast. The three-dimensional time-dependent\nultrasound analysis will greatly aid in the contrast optimization of subsurface\nnanoimaging with US-AFM."
    },
    {
        "anchor": "A general approach for high yield fabrication of CMOS compatible all\n  semiconducting carbon nanotube field effect transistors: We report strategies of achieving both high assembly yield of carbon\nnanotubes at selected position of the circuit via dielectrophoresis (DEP) and\nfield effect transistor (FET) yield using semiconducting enriched single walled\ncarbon nanotube (s-SWNT) aqueous solution. When the DEP parameters were\noptimized for the assembly of individual s-SWNT, 97% of the devices show FET\nbehavior with a maximum mobility of 210 cm2/Vs, on-off current ratio ~ 106 and\non conductance up to 3 {\\mu}S, however with an assembly yield of only 33%. As\nthe DEP parameters were optimized so that 1-5 s-SWNTs are connected per\nelectrode pair, the assembly yield was almost 90% with ~ 90% of these assembled\ndevices demonstrating FET behavior. Further optimization gives an assembly\nyield of 100% with up to 10 SWNT/site, however with a reduced FET yield of 59%.\nImproved FET performance including higher current on-off ratio and high\nswitching speed were obtained by integrating a local Al2O3 gate to the device.\nOur 90% FET with 90% assembly yield is the highest reported so far for carbon\nnanotube devices. Our study provides a pathway which could become a general\napproach for the high yield fabrication of CMOS compatible carbon nanotube\nFETs.",
        "positive": "Tight-binding theory of surface spin states on bismuth thin films: The surface spin states for bismuth thin films were investigated using an\n$sp^3$ tight-binding model. The model explains the experimental observations\nusing angle-resolved photoemission spectroscopy, including the Fermi surface,\nthe band structure with Rashba spin splitting, and the quantum confinement in\nthe energy band gap of the surface states. A large out-of-plane spin component\nalso appears. The surface states penetrate inside the film to within\napproximately a few bilayers near the Brillouin-zone center, whereas they reach\nthe center of the film near the Brillouin-zone boundary."
    },
    {
        "anchor": "3-phonon scattering pathways for vibrational energy transfer in\n  crystalline RDX: A long-held belief is that shock energy induces initiation of an energetic\nmaterial through an indirect energy up-pumping mechanism involving phonon\nscattering through doorway modes. In this paper, a 3-phonon theoretical\nanalysis of energy up-pumping in RDX is presented that involves both direct and\nindirect pathways where the direct energy transfer dominates. The calculation\nconsiders individual phonon modes which are then analyzed in bands. Scattering\nis handled up to the third order term in the Hamiltonian based on Fermi's\nGolden Rule. On average, modes with frequencies up to 90 cm-1 scatter quickly\nand redistribute the energy to all the modes. This direct stimulation occurs\nrapidly, within 0.16 ps, and involves distortions to NN bonds. Modes from 90 to\n1839 cm-1 further up-pump the energy to NN bond distortion modes through an\nindirect route within 5.6 ps. The highest frequency modes have the lowest\ncontribution to energy transfer due to their lower participation in\nphonon-phonon scattering. The modes stimulated directly by the shock with\nfrequencies up to 90 cm-1 are estimated to account for 52 to 89\\% of the total\nenergy transfer to various NN bond distorting modes.",
        "positive": "Vacancy in graphene: insight on magnetic properties from theoretical\n  modeling: Magnetic properties of a single vacancy in graphene is a relevant and still\nunsolved problem. The experimental results point to a clearly detectable\nmagnetic defect state at the Fermi energy, while several calculations based on\ndensity functional theory (DFT) yield widely varying results for the magnetic\nmoment, in the range of $\\mu=1.04-2.0$ $\\mu_{B}$. We present a multi-tool\n\\textit{ab initio} theoretical study of the same defect, using two simulation\nprotocols for a defect in a crystal (cluster and periodic boundary conditions)\nand different DFT functionals - bare and hybrid DFT, mixing a fraction of exact\nHartree-Fock exchange (XC). Our main conclusions are two-fold: First, we find\nthat due to the $\\pi$-character of the Fermi-energy states of graphene,\ninclusion of XC is crucial and for a single isolated vacancy we can predict an\ninteger magnetic moment $\\mu=2\\mu_{B}$. Second, we find that due to the\nspecific symmetry of the graphene lattice, periodic arrays of single vacancies\nmay provide interesting diffuse spin-spin interactions."
    },
    {
        "anchor": "Weak Localization Thickness Measurements of Si:P Delta-Layers: We report on our results for the characterization of Si:P delta-layers grown\nby low temperature molecular beam epitaxy. Our data shows that the effective\nthickness of a delta-layer can be obtained through a weak localization analysis\nof electrical transport measurements performed in perpendicular and parallel\nmagnetic fields. An estimate of the diffusivity of phosphorous in silicon is\nobtained by applying this method to several samples annealed at 850 Celsius for\nintervals of zero to 15 minutes. With further refinements, this may prove to be\nthe most precise method of measuring delta-layer widths developed to date,\nincluding that of Secondary Ion Mass Spectrometry analysis.",
        "positive": "Quantum ballistic transport in in-plane-gate transistors showing onset\n  of a novel ferromagnetic phase transition: We study one-dimensional transport in focused-ion-beam written in-plane-gate\ntransistors on III-V heterostructures at moderately low temperatures at zero\nbias without any external magnetic field applied. In accordance with a recent\nproposal of A. Gold and L. Calmels, Valley- and spin-occupancy instability in\nthe quasi-one-dimensional electron gas, Phil. Mag. Lett. 74, 33-42 (1996) and\nearlier experimental data, we observe plateaux in the source-drain conductivity\nconsidered as a function of the gate voltage, not only at multliples of 2e^2/h\nbut also clearly at e^2/h, just before the channel closes to zero conductivity.\nThis may be interpreted as a many electron effect, namely as a novel ballistic\nferromagnetic ground state evading standard descriptions and theorems."
    },
    {
        "anchor": "Kinetics of the superconducting charge qubit in the presence of a\n  quasiparticle: We investigate the energy and phase relaxation of a superconducting qubit\ncaused by a single quasiparticle. In our model, the qubit is an isolated system\nconsisting of a small island (Cooper-pair box) and a larger superconductor\n(reservoir) connected with each other by a tunable Josephson junction. If such\nsystem contains an odd number of electrons, then even at lowest temperatures a\nsingle quasiparticle is present in the qubit. Tunneling of a quasiparticle\nbetween the reservoir and the Cooper-pair box results in the relaxation of the\nqubit. We derive master equations governing the evolution of the qubit\ncoherences and populations. We find that the kinetics of the qubit can be\ncharacterized by two time scales - quasiparticle escape time from reservoir to\nthe box, $\\Gamma^{-1}_{in}$, and quasiparticle relaxation time $\\tau$. The\nformer is determined by the dimensionless normal-state conductance $g_T$ of the\nJosephson junction and one-electron level spacing $\\delta_r$ in the reservoir\n($\\Gamma_{in}\\sim g_T\\delta_r$), and the latter is due to electron-phonon\ninteraction. We find that phase coherence is damped on the time scale of\n$\\Gamma^{-1}_{in}$. The qubit energy relaxation depends on the ratio of the two\ncharacteristic times, $\\tau$ and $\\Gamma^{-1}_{in}$, and also on the ratio of\ntemperature $T$ to the Josephson energy $E_J$.",
        "positive": "Holographic Vector Field Electron Tomography of Three-Dimensional\n  Nanomagnets: Complex 3D magnetic textures in nanomagnets exhibit rich physical properties,\nfor example in their dynamic interaction with external fields and currents, and\nplay an increasing role for current technological challenges such as\nenergy-efficient memory devices. To study these magnetic nanostructures\nincluding their dependency on geometry, composition and crystallinity, a 3D\ncharacterization of the magnetic field with nanometer spatial resolution is\nindispensable. Here we show how holographic vector field electron tomography\ncan reconstruct all three components of magnetic induction as well as the\nelectrostatic potential of a Co/Cu nanowire with sub 10\\,nm spatial resolution.\nWe address the workflow from acquisition, via image alignment to holographic\nand tomographic reconstruction. Combining the obtained tomographic data with\nmicromagnetic considerations we derive local key magnetic characteristics, such\nas magnetization current or exchange stiffness, and demonstrate how\nmagnetization configurations, such as vortex states in the Co-disks, depend on\nsmall structural variations of the as-grown nanowire."
    },
    {
        "anchor": "Bandwidths Statistics from the Eigenvalue Moments for Harper-Hofstadter\n  Problem: I propose a method for studying the product of bandwidths for the\nHarper-Hofstader model. This method requires knowledge of the moments of the\nmidband energies. I conjectured a general formula for these moments. I computed\nthe asymptotic representation for the product of bandwidths in the limit of a\nweak magnetic flux using Szego's theorem for Hankel matrices. I then give a\nfirst approximation for the edge of the butterfly spectrum and discuss its\nconnection with P. Levy's formula for Brownian motion .",
        "positive": "Decoherence of interacting electrons in disordered conductors: on the\n  relation between influence functional and diagrammatic approaches: We establish a connection between the influence functional approach of\nGolubev and Zaikin (GZ) and Keldysh diagrammatic perturbation theory for\ncalculating the decoherence time of interacting electrons in disordered metals;\nwe show how the standard diagrams for the Cooperon self energy can be recovered\nfrom GZ's influence functional $e^{- (i S_R + S_I)}$. This allows us to shed\nlight on GZ's claim that $S_R$ is irrelevant for decoherence: $S_R$ generates\nas many important self energy diagrams as $S_I$; GZ's neglect of $S_R$ is\npermissible only at high temperatures ($T > \\hbar / \\tau_{el}$)."
    },
    {
        "anchor": "Magneto-optical sensing of the pressure driven magnetic ground states in\n  bulk CrSBr: Competition between exchange interactions and magnetocrystalline anisotropy\nmay bring new magnetic states that are of great current interest. An applied\nhydrostatic pressure can further be used to tune their balance. In this work we\ninvestigate the magnetization process of a biaxial antiferromagnet in an\nexternal magnetic field applied along the easy axis. We find that the single\nmetamagnetic transition of the Ising type observed in this material under\nambient pressure transforms under hydrostatic pressure into two transitions, a\nfirst-order spin flop transition followed by a second order transition towards\na polarized ferromagnetic state near saturation. This reversible tuning into a\nnew magnetic phase is obtained in layered bulk CrSBr at low temperature by\nvarying the interlayer distance using high hydrostatic pressure, which\nefficiently acts on the interlayer magnetic exchange, and is probed by\nmagneto-optical spectroscopy.",
        "positive": "Experimental Realization of Two-Dimensional Boron Sheets: Boron is the fifth element in the periodic table and possesses rich chemistry\nsecond only to carbon. A striking feature of boron is that B12 icosahedral\ncages occur as the building blocks in bulk boron and many boron compounds. This\nis in contrast to its neighboring element, carbon, which prefers 2D layered\nstructure (graphite) in its bulk form. On the other hand, boron clusters of\nmedium size have been predicted to be planar or quasi-planar, such as B12+ ,\nB13+, B19-, B36, and so on. This is also in contrast to carbon clusters which\nexhibit various cage structures (fullerenes). Therefore, boron and carbon can\nbe viewed as a set of complementary chemical systems in their bulk and cluster\nstructures. Now, with the boom of graphene, an intriguing question is that\nwhether boron can also form a monoatomic-layer 2D sheet structure? Here, we\nreport the first successful experimental realization of 2D boron sheets. We\nhave revealed two types of boron sheet structures, corresponding to a\ntriangular boron lattice with different arrangements of the hexagonal holes.\nMoreover, our boron sheets were found to be relatively stable against\noxidization, and interacts only weekly with the substrate. The realization of\nsuch a long expected 2D boron sheet could open a door toward boron electronics,\nin analogous to the carbon electronics based on graphene."
    },
    {
        "anchor": "Response to \"Comment on `Performance of a spin-based insulated gate\n  field effect transistor' [Appl. Phys. Lett. 88, 162503 (2006),\n  cond-mat/0603260]\" [cond-mat/0604532]: A recent e-print (cond-mat/0604532) presented a proposed Comment to Applied\nPhysics Letters on our publication Appl. Phys. Lett. 88, 162503 (2006),\ncond-mat/0603260. Here is our Response. As the proposed Comment has now been\nrejected by Applied Physics Letters, neither the Comment nor the Response will\nbe published in Applied Physics Letters in this form.",
        "positive": "Characterizing Dynamic Majorana Hybridization for Universal Quantum\n  Computing: Qubits built out of Majorana zero modes have long been theorized as a\npotential pathway toward fault-tolerant topological quantum computation. Almost\nunavoidable in these processes is Majorana wavefunction overlap, known as\nhybridization, which arise throughout the process when Majorana modes get close\nto each other. This breaks the ground state degeneracy, leading to qubit errors\nin the braiding process. This work presents an accessible method to track\ntransitions within the low-energy subspace and predict the output of braids\nwith hybridized Majorana modes. As an application, we characterize Pauli\nqubit-errors, as demonstrated on an X-gate, critical for the successful\noperation of any quantum computer. Further, we perform numerical simulations to\ndemonstrate how to utilize the hybridization to implement arbitrary rotations,\nalong with a two-qubit controlled magic gate, thus providing a demonstration of\nuniversal quantum computing."
    },
    {
        "anchor": "Controlled quantum dot array segmentation via a highly tunable interdot\n  tunnel coupling: Recent demonstrations using electron spins stored in quantum dots array as\nqubits are promising for developing a scalable quantum computing platform. An\nongoing effort is therefore aiming at the precise control of the quantum dots\nparameters in larger and larger arrays which represents a complex challenge.\nPartitioning of the system with the help of the inter-dot tunnel barriers can\nlead to a simplification for tuning and offers a protection against unwanted\ncharge displacement. In a triple quantum dot system, we demonstrate a\nnanosecond control of the inter-dot tunnel rate permitting to reach the two\nextreme regimes, large GHz tunnel coupling and sub-Hz isolation between\nadjacent dots. We use this novel development to isolate a sub part of the array\nwhile performing charge displacement and readout in the rest of the system. The\ndegree of control over the tunnel coupling achieved in a unit cell should\nmotivate future protocol development for tuning, manipulation and readout\nincluding this capability.",
        "positive": "Slow inter-minima relaxation and its consequence for BEC of magnons: Two recent articles of the Munster University experimental team led by S.O.\nDemokritov displayed several important facts related to the Bose-Einstein\ncondensation of magnons (BECM) under permanent pumping first discovered in\n2006. They contradicted existing theories of this phenomenon, which predict the\nattractive interaction between magnons and strong spontaneous violation of the\nreflection symmetry. In this article, we show that these theories implicitly\nassumed all relaxation processes to be fast compared with the lifetime of the\nmagnons, whereas one of them -- relaxation between two minima of energy -- is\nslow. We classify processes responsible for the inter-minima relaxation and\npresent their analytic theory. We analyze how the slow inter-minima relaxation\nmodifies the anticipated properties of a ferromagnet with the magnon\ncondensate."
    },
    {
        "anchor": "Coulomb interactions and delocalization in quantum Hall constrictions: We study a geometry-dependent effect of long-range Coulomb interactions on\nquantum Hall (QH) tunneling junctions. In an X-shaped geometry, duality relates\njunctions with opening angles alpha and (pi - alpha). We prove that duality\nbetween weak tunneling and weak backscattering survives in the presence of long\nrange interactions, and that their effects are precisely cancelled in the self\ndual geometry alpha=pi/2. Tunneling exponents as a function of alpha, the\ninteraction strength chi, and the filling fraction nu are calculated. We find\nthat Coulomb interaction induces localization in narrow channels (large alpha),\nand delocalization for sharply pinched constrictions (small alpha).\nConsequently, an insulator to metal transition happens at an angle\nalpha_c(chi,nu) <=pi/2. We discuss the implications of our results for\ntunneling experiments in QH-constriction and cleaved-edge geometries.",
        "positive": "Analytical expression of geometrical pumping for a quantum dot based on\n  quantum master equation: We analytically investigate a non-equilibrium quantum pumping for a single\nquantum dot connected to external leads on the basis of the quantum master\nequation (QME). We show that the Coulomb interaction associated with the spin\neffect in the dot induces the Berry-like phase in the parameter space and this\nphase results in the excess charge transfer for the cyclic modulation of\nparameters in leads. We obtain an analytical expression of the curvature of the\nphase and that for the pumped currents."
    },
    {
        "anchor": "Micromagnets dramatically enhance effects of viscous hydrodynamic flow\n  in two-dimensional electron fluid: The hydrodynamic behavior of electron fluids in a certain range of\ntemperatures and densities is well established in graphene and in 2D\nsemiconductor heterostructures. The hydrodynamic regime is intrinsically based\non electron-electron interactions, and therefore it provides a unique\nopportunity to study electron correlations. Unfortunately, in all existing\nmeasurements, the relative contribution of hydrodynamic effects to transport is\nrather small. Viscous hydrodynamic effects are masked by impurities,\ninteraction with phonons, uncontrolled boundaries and ballistic effects. This\nessentially limits the accuracy of measurements of electron viscosity.\nFundamentally, what causes viscous friction in the electron fluid is the\nproperty of the flow called vorticity. In this paper, we propose to use\nmicromagnets to increase the vorticity by orders of magnitude. Experimental\nrealization of this proposal will bring electron hydrodynamics to a\nqualitatively new precision level, as well as opening a new way to characterize\nand externally control the electron fluid.",
        "positive": "Quantum Hall Circle: We consider spin-polarized electrons in a single Landau level on a cylinder\nas the circumference of the cylinder goes to infinity. This gives a model of\ninteracting electrons on a circle where the momenta of the particles are\nrestricted and there is no kinetic energy. Quantum Hall states are exact ground\nstates for appropriate short range interactions, and there is a gap to\nexcitations. These states develop adiabatically from this one-dimensional\nquantum Hall circle to the bulk quantum Hall states and further on into the\nTao-Thouless states as the circumference goes to zero. For low filling\nfractions a gapless state is formed which we suggest is connected to the Wigner\ncrystal expected in the bulk."
    },
    {
        "anchor": "Optical manipulation of a magnon-photon hybrid system: We demonstrate an all-optical method for manipulating the magnetization in a\n1-mm YIG (yttrium-iron-garnet) sphere placed in a $\\sim0.17\\,$T uniform\nmagnetic field. An harmonic of the frequency comb delivered by a multi-GHz\ninfrared laser source is tuned to the Larmor frequency of the YIG sphere to\ndrive magnetization oscillations, which in turn give rise to a radiation field\nused to thoroughly investigate the phenomenon. The radiation damping issue that\noccurs at high frequency and in the presence of highly magnetizated materials,\nhas been overcome by exploiting magnon-photon strong coupling regime in\nmicrowave cavities. Our findings demonstrate an effective technique for\nultrafast control of the magnetization vector in optomagnetic materials via\npolarization rotation and intensity modulation of an incident laser beam. We\neventually get a second-order susceptibility value of $\\sim10^{-7}$ cm$^2$/MW\nfor single crystal YIG.",
        "positive": "Transmission of a Symmetric Light Pulse through a Wide QW: The reflection, transmission and absorption of a symmetric electromagnetic\npulse, which carrying frequency is close to the frequency of an interband\ntransition in a QW (QW), are obtained. The energy levels of a QW are assumed\ndiscrete, one exited level is taken into account. The case of a wide QW is\nconsidered when a length of the pulse wave, appropriate to the carrying\nfrequency, is comparable to the QW's width. In figures the time dependencies of\nthe dimensionless reflection, absorption are transmission are represented. It\nis shown, that the spatial dispersion and a distinction in refraction indexes\ninfluence stronger reflection."
    },
    {
        "anchor": "Hidden area and mechanical nonlinearities in freestanding graphene: We investigated the effect of out-of-plane crumpling on the mechanical\nresponse of graphene membranes. In our experiments, stress was applied to\ngraphene membranes using pressurized gas while the strain state was monitored\nthrough two complementary techniques: interferometric profilometry and Raman\nspectroscopy. By comparing the data obtained through these two techniques, we\ndetermined the geometric hidden area which quantifies the crumpling strength.\nWhile the devices with hidden area $\\sim0~\\%$ obeyed linear mechanics with\nbiaxial stiffness $428\\pm10$ N/m, specimens with hidden area in the range\n$0.5-1.0~\\%$ were found to obey an anomalous Hooke's law with an exponent\n$\\sim0.1$.",
        "positive": "Fingerprint of Different Spin-Orbit Terms for Spin Transport in HgTe\n  Quantum Wells: Using $\\vec{k}$$\\cdot$$\\vec{p}$ theory, we derive an effective four band\nmodel describing the physics of the typical two-dimensional topological\ninsulator (HgTe/CdTe quantum well) in the presence of out-of-plane in\nz-direction inversion breaking and in-plane confining potentials. We find that\nup to third order in perturbation theory, only the inversion breaking potential\ngenerates new elements to the four band Hamiltonian that are off-diagonal in\nspin space. When this new effective Hamiltonian is folded into an effective two\nband model for the conduction (electron) or valence (heavy hole) bands, two\ncompeting terms appear: (1) a Rashba spin-orbit interaction originating from\ninversion breaking potential in z-direction and (2) an in-plane Pauli term as a\nconsequence of the in-plane confining potential. Spin transport in the\nconduction band is further analysed within the Landauer-B\\\"uttiker formalism.\nWe find that for asymmetrically doped HgTe quantum wells, the behaviour of the\nspin-Hall conductance is dominated by the Rashba term."
    },
    {
        "anchor": "Low-temperature electron dephasing time in AuPd revisited: Ever since the first discoveries of the quantum-interference transport in\nmesoscopic systems, the electron dephasing times, $\\tau_\\phi$, in the\nconcentrated AuPd alloys have been extensively measured. The samples were made\nfrom different sources with different compositions, prepared by different\ndeposition methods, and various geometries (1D narrow wires, 2D thin films, and\n3D thickfilms) were studied. Surprisingly, the low-temperature behavior of\n$\\tau_\\phi$ inferred by different groups over two decades reveals a systematic\ncorrelation with the level of disorder of the sample. At low temperatures,\nwhere $\\tau_\\phi$ is (nearly) independent of temperature, a scaling\n$\\tau_\\phi^{\\rm max} \\propto D^{-\\alpha}$ is found, where $tau_\\phi^{\\rm max}$\nis the maximum value of $\\tau_\\phi$ measured in the experiment, $D$ is the\nelectron diffusion constant, and the exponent $\\alpha$ is close to or slightly\nlarger than 1. We address this nontrivial scaling behavior and suggest that the\nmost possible origin for this unusual dephasing is due to dynamical structure\ndefects, while other theoretical explanations may not be totally ruled out.",
        "positive": "Zero-energy states of graphene triangular quantum dots in a magnetic\n  field: We present a tight-binding theory of triangular graphene quantum dots (TGQD)\nwith zigzag edge and broken sublattice symmetry in external magnetic field. The\nlateral size quantization opens an energy gap and broken sublattice symmetry\nresults in a shell of degenerate states at the Fermi level. We derive a\nsemi-analytical form for zero-energy states in a magnetic field and show that\nthe shell remains degenerate in a magnetic field, in analogy to the 0th Landau\nlevel of bulk graphene. The magnetic field closes the energy gap and leads to\nthe crossing of valence and conduction states with the zero-energy states,\nmodulating the degeneracy of the shell. The closing of the gap with increasing\nmagnetic field is present in all graphene quantum dot structures investigated\nirrespective of shape and edge termination."
    },
    {
        "anchor": "Imaging stress and magnetism at high pressures using a nanoscale quantum\n  sensor: Pressure alters the physical, chemical and electronic properties of matter.\nThe development of the diamond anvil cell (DAC) enables tabletop experiments to\ninvestigate a diverse landscape of high-pressure phenomena ranging from the\nproperties of planetary interiors to transitions between quantum mechanical\nphases. In this work, we introduce and utilize a novel nanoscale sensing\nplatform, which integrates nitrogen-vacancy (NV) color centers directly into\nthe culet (tip) of diamond anvils. We demonstrate the versatility of this\nplatform by performing diffraction-limited imaging (~600 nm) of both stress\nfields and magnetism, up to pressures ~30 GPa and for temperatures ranging from\n25-340 K. For the former, we quantify all six (normal and shear) stress\ncomponents with accuracy $<0.01$ GPa, offering unique new capabilities for\ncharacterizing the strength and effective viscosity of solids and fluids under\npressure. For the latter, we demonstrate vector magnetic field imaging with\ndipole accuracy $<10^{-11}$ emu, enabling us to measure the pressure-driven\n$\\alpha\\leftrightarrow\\epsilon$ phase transition in iron as well as the complex\npressure-temperature phase diagram of gadolinium. In addition to DC vector\nmagnetometry, we highlight a complementary NV-sensing modality using T1 noise\nspectroscopy; crucially, this demonstrates our ability to characterize phase\ntransitions even in the absence of static magnetic signatures. By integrating\nan atomic-scale sensor directly into DACs, our platform enables the in situ\nimaging of elastic, electric and magnetic phenomena at high pressures.",
        "positive": "Noise induced effects at nano-structured thin films growth during\n  deposition in plasma-condensate devices: We perform a comprehensive study of noise-induced effects in a stochastic\nmodel of reaction-diffusion type, describing nano-structured thin films growth\nat condensation. We introduce an external flux of adsorbate between neighbour\nmonoatomic layers caused by the electrical field presence near substrate in\nplasma-condensate devices. We take into account that the strength of the\nelectric field fluctuates around its mean value. We discuss a competing\ninfluence of the regular and stochastic parts of the external flux onto the\ndynamics of adsorptive system. It will be shown that the introduced\nfluctuations induce first-order phase transition in a homogeneous system,\ngovern the pattern formation in a spatially extended system; these parts of the\nflux control the dynamics of the patterning, spatial order, morphology of the\nsurface, growth law of the mean size of adsorbate islands, type and linear size\nof surface structures. The influence of the intensity of fluctuations onto\nscaling and statistical properties of the nano-structured surface is analysed\nin detail. This study provides an insight into the details of noise induced\neffects at pattern formation processes in anisotropic adsorptive systems."
    },
    {
        "anchor": "Degenerate Topological Edge States in Multimer Chains: We propose and experimentally realize a class of quasi-one-dimensional\ntopological lattices whose unit cells are constructed by coupled multiple\nidentical resonators, with uniform hopping and inversion symmetry. In the\npresence of path-induced effective zero hopping within the unit cells, the\nsystems are characterized by complete multimerization with degenerate $-1$\nenergy edge states for open boundary condition. Su-Schrieffer-Heeger subspaces\nwith fully dimerized limits corresponding to pairs of nontrivial flat bands are\nderived from the Hilbert spaces. In particular, topological bound states in the\ncontinuum (BICs) are inherently present in even multimer chains, manifested by\nembedding the topological bound states into a continuous band assured by\nbulk-boundary correspondence. Moreover, we experimentally demonstrate the\ndegenerate topological edge states and topological BICs in inductor-capacitor\ncircuits.",
        "positive": "Minimal Model of Spin-Transfer Torque and Spin Pumping caused by Spin\n  Hall Effect: In the normal metal/ferromagnetic insulator bilayer (such as\nPt/Y$_{3}$Fe$_{5}$O$_{12}$) and the normal metal/ferromagnetic metal/oxide\ntrilayer (such as Pt/Co/AlO$_{x}$) where spin injection and ejection are\nachieved by the spin Hall effect in the normal metal, we propose a minimal\nmodel based on quantum tunneling of spins to explain the spin-transfer torque\nand spin pumping caused by the spin Hall effect. The ratio of their\ndamping-like to field-like component depends on the tunneling wave function\nthat is strongly influenced by generic material properties such as interface\n$s-d$ coupling, insulating gap, and layer thickness, yet the spin relaxation\nplays a minor role. The quantified result renders our minimal model an\ninexpensive tool for searching for appropriate materials."
    },
    {
        "anchor": "Topological dephasing in the $\u03bd=2/3$ fractional Quantum Hall Regime: We study dephasing in electron transport through a large quantum dot (a\nFabry-Perot interferometer) in the fractional quantum Hall regime with filling\nfactor $2/3$. In the regime of sequential tunneling, dephasing occurs due to\nelectron fractionalization into counterpropagating charge and neutral edge\nmodes on the dot. In particular, when the charge mode moves much faster than\nthe neutral mode, and at temperatures higher than the level spacing of the dot,\nelectron fractionalization combined with tje fractional statistics of the\ncharge mode leads to the dephasing selectively suppressing $h/e$ Aharonov-Bohm\noscillations but not $h/(2e)$ oscillations, resulting in oscillation-period\nhalving.",
        "positive": "Signatures of band-like tunnelling in granular nanowires: We explore the problem of tunneling through disorderd nanowires, comprised of\na random distribution of metallic grains, by means of a many-body model that\ncaptures the essential physics of the system. The random configuration of\ngrains gives rise to a smooth band-like set of states, which mediates current\nflow through the nanowire. Analytical and numerical calculations show the\ncharacteristic signature of this unusual band-like transport to be a quadratic\nvariation of the current as a function of the applied voltage (i.e. $I\\sim\nV^2$), a variation that is clearly observed in experimental studies of Pt/C\ncomposite nanowires."
    },
    {
        "anchor": "Skyrmion dynamics in quantum Hall ferromagnets: Exploring a classical solution of the non-linear sigma model for a quantum\nHall ferromagnet, a skyrmion-magnon effective hamiltonian is obtained via the\ncollective coordinates method. Using the Feynman-Vernon functional integral\nformalism for this model we find the temperature dependent transport\ncoefficients which characterize a single skyrmion dynamics.",
        "positive": "Marginal Fermi liquid in twisted bilayer graphene: Linear resistivity at low temperatures is a prominent feature of high-T$_c$\nsuperconductors which has also been found recently in twisted bilayer graphene.\nWe show that due to an extended van Hove singularity (vHS), the $T$-linear\nresistivity can be obtained from a microscopic tight-binding model for filling\nfactors close to the vHS. The linear behavior is shown to be related to the\nlinear energy dependence of the electron quasiparticle decay rate which implies\nthe low-energy logarithmic attenuation of the quasiparticle weight. These are\ndistinctive features of a marginal Fermi liquid, which we also see reflected in\nthe respective low-temperature logarithmic corrections of the heat capacity and\nthe thermal conductivity, leading to the consequent violation of the\nWiedemann-Franz law. We also show that there is a crossover at $T \\sim 6$ K\nfrom the marginal Fermi liquid regime to a regime dominated by excitations on\nthe Dirac cone right above the vHS that also yields a linear resistivity albeit\nwith smaller slope, in agreement with experimental observations."
    },
    {
        "anchor": "Transverse Magnetoresistance of Zn$_{0.9}$Co$_{0.1}$O:Al Thin Films: The transverse magnetoresistance of thin films of the Diluted Magnetic\nSemiconductor Zn$_{1-x}$Co$_{x}$O:Al on glass was studied for temperatures in\nthe range of 5 to 100 K. Measurements were made on thin films grown by rf\nmagnetron sputtering, with a thickness of approximately 200 nm. ZnO was alloyed\nwith Co to a concentration $x$ of 0.1 and co-doped with a 5.5% wt concentration\nof Al. The electrical resistivity was measured along the sample surface by the\nfour-point probe method with a magnetic field of up to 4 T applied\nperpendicular to the surface of the film. The experimental results of the\nmagnetoresistance have been interpreted by means of a semiclassical model that\ncombines a relaxation-time approximation to describe scattering processes in\nZnO and a phenomenological approach to the spin-disorder scattering due to the\nindirect exchange interaction of the magnetic impurities.",
        "positive": "Chirality-dependent persistent spin current in single circular helix\n  molecules: Since the chiral-induced spin selectivity (CISS) was first observed\nexperimentally, its microscopic mechanism has been continuously explored by the\nscientific community. Among these investigations, the non-equilibrium effects\nand the unknown origins of spin-orbit coupling (SOC) have been the central\nissues discussed in recent years. Here, we have achieved a persistent spin\ncurrent in different circular single-helix molecule driven by a magnetic field,\nwhich is inherently linked to the equilibrium state associated with chirality.\nDue to its measurement method being different from the transport currents\nobserved in previous experiments, the origin of its spin-orbit coupling can be\nexplored by modifying the substrate with different light and heavy metal\nelements. Our results demonstrate that a persistent spin current can be\nobserved regardless of whether the SOC originates from the chiral molecule or\nthe substrate. Furthermore, by tuning the direction of the magnetic field, we\ncan achieve a phase transition between trivial and non-trivial chiral\npersistent spin currents. Our work provides a new perspective and platform for\nexploring the nature of CISS and controlling the effects of CISS."
    },
    {
        "anchor": "Critical behavior of sputter-deposited magnetoelectric antiferromagnetic\n  Cr$_2$O$_3$ films near N\u00e9el temperature: Chromium(III) oxide is a classical collinear antiferromagnet with a linear\nmagnetoelectric effect. We are presenting the measurements of the\nmagnetoelectric susceptibility $\\alpha$ of a sputter-deposited 500-nm film and\na bulk single-crystal of Cr$_\\mathrm{2}$O$_\\mathrm{3}$. We investigated the\nmagnetic phase-transition and the critical exponent $\\beta$ of the sublattice\nmagnetization near N\\'eel temperature. For the films, an exponent of 0.49(1)\nwas found below 293 K, and changed to 1.06(4) near the N\\'eel temperature of\n298 K. For the single-crystal, the exponent was constant at 0.324(4). We\ninvestigated the reversal probability of antiferromagnetic domains during\nmagnetoelectric field cooling. For the sputtered films, reversal probability\nwas zero above 298 K and stabilized only below 293 K. We attribute this\nbehavior to formation of grains during film growth, which gives different\nintergrain and intragrain exchange-coupling energies. For the single-crystal,\nreversal probability was stabilized immediately at the N\\'eel temperature of\n307.6 K.",
        "positive": "Disorder regimes and equivalence of disorder types in artificial spin\n  ice: The field-induced dynamics of artificial spin ice are determined in part by\ninteractions between magnetic islands, and the switching characteristics of\neach island. Disorder in either of these affects the response to applied\nfields. Numerical simulations are used to show that disorder effects are\ndetermined primarily by the strength of disorder relative to inter-island\ninteractions, rather than by the type of disorder. Weak and strong disorder\nregimes exist and can be defined in a quantitative way."
    },
    {
        "anchor": "Anomalous Freezing of Low Dimensional Water Confined in Graphene\n  Nanowrinkles: Various properties of water are affected by confinement as the space-filling\nof the water molecules is very different from bulk water. In our study, we\nchallenged the creation of a stable system in which water molecules are\npermanently locked in nanodimensional graphene traps. For that purpose, we\ndeveloped a technique, nitrocellulose-assisted transfer of graphene grown by\nchemical vapor deposition, which enables capturing of the water molecules below\nan atomically thin graphene membrane structured into a net of regular wrinkles\nwith a lateral dimension of about 4 nm. After successfully confining water\nmolecules below a graphene monolayer, we employed cryogenic Raman spectroscopy\nto monitor the phase changes of the confined water as a function of the\ntemperature. In our experiment system, the graphene monolayer structured into a\nnet of fine wrinkles plays a dual role: (i) it enables water confinement and\n(ii) serves as an extremely sensitive probe for phase transitions involving\nwater via graphene-based spectroscopic monitoring of the underlying water\nstructure. Experimental findings were supported with classical and path\nintegral molecular dynamics simulations carried out on our experimental system.",
        "positive": "Confinement versus interface bound states in spin-orbit coupled\n  nanowires: Semiconductor nanowires with strong Rashba spin-orbit coupling are currently\non the spotlight of several research fields such as spintronics, topological\nmaterials and quantum computation. While most theoretical models assume an\ninfinitely long nanowire, in actual experimental setups the nanowire has a\nfinite length, is contacted to metallic electrodes and is partly covered by\ngates. By taking these effects into account through an inhomogeneous spin-orbit\ncoupling profile, we show that in general two types of bound states arise in\nthe nanowire, namely confinement bound states and interface bound states. The\nappearance of confinement bound states, related to the finite length of the\nnanowire, is favoured by a mismatch of the bulk band bottoms characterizing the\nlead and the nanowire, and occurs even in the absence of magnetic field. In\ncontrast, an interface bound states may only appear if a magnetic field applied\nperpendicularly to the spin-orbit field direction overcomes a critical value,\nand is favoured by an alignment of the band bottoms of the two regions across\nthe interface. We describe in details the emergence of these two types of bound\nstates, pointing out their differences. Furthermore, we show that when a\nnanowire portion is covered by a gate the application of a magnetic field can\nchange the nature of the electronic ground state from a confinement to an\ninterface bound state, determining a redistribution of the electron charge."
    },
    {
        "anchor": "Twistronics: Manipulating the Electronic Properties of Two-dimensional\n  Layered Structures through their Twist Angle: The ability in experiments to control the relative twist angle between\nsuccessive layers in two-dimensional (2D) materials offers a new approach to\nmanipulating their electronic properties; we refer to this approach as\n\"twistronics\". A major challenge to theory is that, for arbitrary twist angles,\nthe resulting structure involves incommensurate (aperiodic) 2D lattices. Here,\nwe present a general method for the calculation of the electronic density of\nstates of aperiodic 2D layered materials, using parameter-free hamiltonians\nderived from ab initio density-functional theory. We use graphene, a semimetal,\nand MoS$_2$, a representative of the transition metal dichalcogenide (TMDC)\nfamily of 2D semiconductors, to illustrate the application of our method, which\nenables fast and efficient simulation of multi-layered stacks in the presence\nof local disorder and external fields. We comment on the interesting features\nof their Density of States (DoS) as a function of twist-angle and local\nconfiguration and on how these features can be experimentally observed.",
        "positive": "Quasiparticle poisoning effects on the dynamics of topological Josephson\n  junctions: The fractional Josephson effect remains one of the decisive hallmarks of\ntopologically protected Majorana zero modes. We analyze the effects of parity\nviolating quasiparticle poisoning onto the current voltage characteristics of\ntopological Josephson junctions. We include poisoning events directly within\nthe resistively shunted junction (RSJ) model in the overdamped limit both in\nthe short- and long-junction regime. We calculate the current voltage\ncharacteristics numerically where poisoning is modeled either via additional\nrates in the Fokker-Planck equations or by a time dependent parity and compare\nthem to the limits of no and strong poisoning rates which we obtain\nanalytically. Combining the tilted washboard potential with poisoning events,\nwe show that the critical current of the long junction limit can be used as a\nprobe of the junction topology even in the high temperature poisoning case\nwhere relaxation- and excitation processes are equally likely. Using the tilted\nwashboard potential model we develop three different schemes to measure the\npoisoning rate thereby also extending the consideration to two pairs of helical\nedge states containing a constriction that allows for tunneling between the two\npairs of edge states."
    },
    {
        "anchor": "Microscopic approach to current-driven domain wall dynamics: This review describes in detail the essential techniques used in microscopic\ntheories on spintronics. We have investigated the domain wall dynamics induced\nby electric current based on the $s$-$d$ exchange model. The domain wall is\ntreated as rigid and planar and is described by two collective coordinates: the\nposition and angle of wall magnetization. The effect of conduction electrons on\nthe domain wall dynamics is calculated in the case of slowly varying spin\nstructure (close to the adiabatic limit) by use of a gauge transformation. The\nspin-transfer torque and force on the wall are expressed by Feynman diagrams\nand calculated systematically using non-equilibrium Green's functions, treating\nelectrons fully quantum mechanically. The wall dynamics is discussed based on\ntwo coupled equations of motion derived for two collective coordinates. The\nforce is related to electron transport properties, resistivity, and the Hall\neffect. Effect of conduction electron spin relaxation on the torque and wall\ndynamics is also studied.",
        "positive": "Hyperfine-induced spin relaxation of a diffusively moving carrier in low\n  dimensions: implications for spin transport in organic semiconductors: The hyperfine coupling between the spin of a charge carrier and the nuclear\nspin bath is a predominant channel for the carrier spin relaxation in many\norganic semiconductors. We theoretically investigate the hyperfine-induced spin\nrelaxation of a carrier performing a random walk on a d-dimensional regular\nlattice, in a transport regime typical for organic semiconductors. We show that\nin d=1 and d=2 the time dependence of the space-integrated spin polarization,\nP(t), is dominated by a superexponential decay, crossing over to a stretched\nexponential tail at long times. The faster decay is attributed to multiple\nself-intersections (returns) of the random walk trajectories, which occur more\noften in lower dimensions. We also show, analytically and numerically, that the\nreturns lead to sensitivity of P(t) to external electric and magnetic fields,\nand this sensitivity strongly depends on dimensionality of the system (d=1 vs.\nd=3). Furthermore, we investigate in detail the coordinate dependence of the\ntime-integrated spin polarization, $\\sigma(r)$, which can be probed in the spin\ntransport experiments with spin-polarized electrodes. We demonstrate that,\nwhile $\\sigma(r)$ is essentially exponential, the effect of multiple\nself-intersections can be identified in transport measurements from the strong\ndependence of the spin decay length on the external magnetic and electric\nfields."
    },
    {
        "anchor": "Tunable Electronic Structure in Gallium Chalcogenide van der Waals\n  Compounds: Transition metal monochalcogenides comprise a class of two-dimensional\nmaterials with electronic band gaps that are highly sensitive to material\nthickness and chemical composition. Here, we explore the tunability of the\nelectronic excitation spectrum in GaSe using angle-resolved photoemission\nspectroscopy. The electronic structure of the material is modified by\n$\\textit{in-situ}$ potassium deposition as well as by forming\nGaS$_{x}$Se$_{1-x}$ alloy compounds. We find that potassium decouples the\ntop-most tetra-layer of the GaSe unit cell, leading to a substantial change of\nthe dispersion around the valence band maximum (VBM). The observed band\ndispersion of a single tetralayer is consistent with a transition from the\ndirect gap character of the bulk to the indirect gap character expected for\nmonolayer GaSe. Upon alloying with sulfur, we observe a phase transition from\nAB to $\\text{AA}^{\\prime}$ stacking. Alloying also results in a rigid energy\nshift of the VBM towards higher binding energies which correlates with a blue\nshift in the luminescence. The increase of the band gap upon sulfur alloying\ndoes not appear to change the dispersion or character of the VBM appreciably,\nimplying that it is possible to engineer the gap of these materials while\nmaintaining their salient electronic properties.",
        "positive": "Topological interface states -- a possible path towards a Landau-level\n  laser in the THz regime: Volkov-Pankratov surface bands arise in smooth topological interfaces, i.e.\ninterfaces between a topological and a trivial insulator, in addition to the\nchiral surface state imposed by the bulk-surface correspondence of topological\nmaterials. These two-dimensional bands become Landau-quantized if a magnetic\nfield is applied perpendicular to the interface. I show that the energy scales,\nwhich are typically in the 10-100 meV range, can be controlled both by the\nperpendicular magnetic field and the interface width. The latter can still be\nvaried with the help of a magnetic-field component in the interface. The Landau\nlevels of the different Volkov-Pankratov bands are optically coupled, and their\narrangement may allow one to obtain population inversion by resonant optical\npumping. This could serve as the elementary brick of a multi-level laser based\non Landau levels. Moreover, the photons are absorbed and emitted either\nparallel or perpendicular to the magnetic field, respectively in the Voigt and\nFaraday geometry, depending on the Volkov-Pankratov bands and Landau levels\ninvolved in the optical transitions."
    },
    {
        "anchor": "Heat dissipation in atomic-scale junctions: Atomic and single-molecule junctions represent the ultimate limit to the\nminiaturization of electrical circuits. They are also ideal platforms to test\nquantum transport theories that are required to describe charge and energy\ntransfer in novel functional nanodevices. Recent work has successfully probed\nelectric and thermoelectric phenomena in atomic-scale junctions. However, heat\ndissipation and transport in atomic-scale devices remain poorly characterized\ndue to experimental challenges. Here, using custom-fabricated scanning probes\nwith integrated nanoscale thermocouples, we show that heat dissipation in the\nelectrodes of molecular junctions, whose transmission characteristics are\nstrongly dependent on energy, is asymmetric, i.e. unequal and dependent on both\nthe bias polarity and the identity of majority charge carriers (electrons vs.\nholes). In contrast, atomic junctions whose transmission characteristics show\nweak energy dependence do not exhibit appreciable asymmetry. Our results\nunambiguously relate the electronic transmission characteristics of\natomic-scale junctions to their heat dissipation properties establishing a\nframework for understanding heat dissipation in a range of mesoscopic systems\nwhere transport is elastic. We anticipate that the techniques established here\nwill enable the study of Peltier effects at the atomic scale, a field that has\nbeen barely explored experimentally despite interesting theoretical\npredictions. Furthermore, the experimental advances described here are also\nexpected to enable the study of heat transport in atomic and molecular\njunctions, which is an important and challenging scientific and technological\ngoal that has remained elusive.",
        "positive": "Multidimensional optomechanical cantilevers for high frequency atomic\n  force microscopy: High-frequency atomic force microscopy has enabled extraordinary new science\nthrough large bandwidth, high speed measurements of atomic and molecular\nstructures. However, traditional optical detection schemes restrict the\ndimensions, and therefore the frequency, of the cantilever - ultimately setting\na limit to the time resolution of experiments. Here we demonstrate\noptomechanical detection of low-mass, high-frequency nanomechanical cantilevers\n(up to 20 MHz) that surpass these limits, anticipating their use for\nsingle-molecule force measurements. These cantilevers achieve 2 fm / sqrt(Hz)\ndisplacement noise floors, and force sensitivity down to 132 aN / sqrt(Hz).\nFurthermore, the ability to resolve both in-plane and out-of-plane motion of\nour cantilevers opens the door for ultrasensitive multidimensional force\nspectroscopy, and optomechanical interactions, such as tuning of the cantilever\nfrequency in situ, provide new opportunities in high-speed, high-resolution\nexperiments."
    },
    {
        "anchor": "Valley two-qubit system in a MoS$_2$-monolayer gated double quantum dot: We explore a two-qubit system defined on valley isospins of two electrons\nconfined in a gate-defined double quantum dot created within a MoS$_2$\nmonolayer flake. We show how to initialize, control, interact and read out such\nvalley qubits only by electrical means using voltages applied to the local\nplanar gates, which are layered on the top of the flake. By demonstrating the\ntwo-qubit exchange or readout via the Pauli blockade, we prove that valley\nqubits in transition-metal-dichalcogenide semiconductors family fulfill the\nuniversality criteria and represent a scalable quantum computing platform. Our\nnumerical experiments are based on the tight-binding model for a MoS$_2$\nmonolayer, which gives single-electron eigenstates that are then used to\nconstruct a basis of Slater-determinants for the two-electron configuration\nspace. We express screened electron-electron interactions in this basis by\ncalculating the Coulomb matrix elements using localized Slater-type orbitals.\nThen we solve the time-dependent Schr\\\"odinger equation and obtain an exact\ntime-evolution of the two-electron system. During the evolution we\nsimultaneously solve the Poison equation, finding the confinement potential\ncontrolled via voltages applied to the gates.",
        "positive": "Extracting net current from an upstream neutral mode in the fractional\n  quantum Hall regime: Upstream neutral modes, counter propagating to charge modes and carrying\nenergy without net charge, had been predicted to exist in some of the\nfractional quantum Hall states and were recently observed via noise\nmeasurements. Understanding such modes will assist in identifying the\nwavefunction of these states, as well as shedding light on the role of Coulomb\ninteractions within edge modes. In this work, performed mainly in the nu=2/3\nstate, we placed a quantum dot a few micrometers upstream of an ohmic contact,\nwhich served as a neutral modes source. We showed the neutral modes heat the\ninput of the dot, causing a net thermo-electric current to flow through it.\nHeating of the electrons led to a decay of the neutral mode, manifested in the\nvanishing of the thermo-electric current at T>110mK. This setup provides a\nstraightforward method to investigate upstream neutral modes without turning to\nthe more cumbersome noise measurements."
    },
    {
        "anchor": "Hole spin driving by strain-induced spin-orbit interactions: Hole spins in semiconductor quantum dots can be efficiently manipulated with\nradio-frequency electric fields owing to the strong spin-orbit interactions in\nthe valence bands. Here we show that the motion of the dot in inhomogeneous\nstrain fields gives rise to linear Rashba spin-orbit interactions (with\nspatially dependent spin-orbit lengths) and g-factor modulations that allow for\nfast Rabi oscillations. Such inhomogeneous strains may build up spontaneously\ndue to process and cool down stress. We discuss spin qubits in Ge/GeSi\nheterostructures as an illustration. We highlight that Rabi frequencies can be\nenhanced by one order of magnitude by shear strain gradients as small as\n$3\\times 10^{-6}$ nm$^{-1}$ within the dots. This underlines that spin in\nsolids can be very sensitive to strains and opens the way for strain\nengineering in hole spin devices for quantum information and spintronics.",
        "positive": "Spin-orbit coupling and spin transport: Recent achievements in semiconductor spintronics are discussed. Special\nattention is paid to spin-orbit interaction, coupling of electron spins to\nexternal electric fields, and spin transport in media with spin-orbit coupling,\nincluding the mechanisms of spin-Hall effect. Importance of spin-transport\nparameters at spin-precession wave vector $k_{\\rm so}$ is emphasized, and\nexistence of an universal relation between spin currents and spin accumulation\nat the spatial scale of $\\ell_{\\rm so}\\approx k_{\\rm so}^{-1}$ is conjectured."
    },
    {
        "anchor": "Role of dipolar interactions in a system of Ni nanoparticles studied by\n  magnetic susceptibility measurements: The role of dipolar interactions among Ni nanoparticles (NP) embedded in an\namorphous SiO2/C matrix with different concentrations has been studied\nperforming ac magnetic susceptibility Chi_ac measurements. For very diluted\nsamples, with Ni concentrations < 4 wt % Ni or very weak dipolar interactions,\nthe data are well described by the Neel-Arrhenius law. Increasing Ni\nconcentration to values up to 12.8 wt % Ni results in changes in the\nNeel-Arrhenius behavior, the dipolar interactions become important, and need to\nbe considered to describe the magnetic response of the NPs system. We have\nfound no evidence of a spin-glasslike behavior in our Ni NP systems even when\ndipolar interactions are clearly present.",
        "positive": "Spin-torque driven magnetic vortex self-oscillations in perpendicular\n  magnetic fields: We have employed complete micromagnetic simulations to analyze dc current\ndriven self-oscillations of a vortex core in a spin-valve nanopillar in a\nperpendicular field by including the coupled effect of the spin-torque and the\nmagnetostatic field computed self-consistently for the entire spin-valve. The\nvortex in the thicker nanomagnet moves along a quasi-elliptical trajectory that\nexpands with applied current, resulting in blue-shifting of the frequency,\nwhile the magnetization of the thinner nanomagnet is non-uniform due to the\nbias current. The simulations explain the experimental magnetoresistance-field\nhysteresis loop and yield good agreement with the measured frequency vs.\ncurrent behavior of this spin-torque vortex oscillator."
    },
    {
        "anchor": "Persistent current and correlation effects in carbon nanotubes: The persistent current of interacting electrons in toroidal single-wall\ncarbon nanotubes is evaluated within Haldane's concept of topological\nexcitations. The overall pattern of the persistent current corresponds to the\nconstant interaction model, whereas the fine structure stems from the\nelectronic exchange correlations.",
        "positive": "Phase and Thermal Driven Transport across T-Shaped Double Quantum Dot\n  Josephson Junction: The phase and thermal driven transport properties of the T-shaped\nuncorrelated double quantum dot Josephson junction are analyzed by using\nKeldysh non-equilibrium Green's function equation of motion technique. In this\nsetup, we have shown that the side-attached quantum dot provides an additional\nroute for electron transmission which is affecting the transport properties by\nadjusting the interdot hopping between the main dot and the side dot. We began\nwith investigating the impact of interdot hopping on Andreev bound states and\nJosephson supercurrent. When a small thermal bias is applied across the\nsuperconducting leads, the system exhibits a finite thermal response which is\nprimarily due to the, thermally induced, quasi-particle current. The behavior\nof the Josephson supercurrent and the quasi-particle current flowing through\nthe quantum dots is examined for various interdot hopping and thermal biasing.\nFinally, the system is considered in an open circuit configuration where the\nthermally driven quasi-particle current is compensated by the phase-driven\nJosephson supercurrent and the thermophase effect is observed. The effect of\ninterdot hopping and the position of quantum dot energy level on the\nthermophase Seebeck coefficient is investigated"
    },
    {
        "anchor": "Thermopower Oscillation Symmetries in a Double-Loop Andreev\n  Interferrometer: Andreev interferometers, normal metal wires coupled to superconducting loops,\ndisplay phase coherent changes as the magnetic flux through the superconducting\nloops is altered. Properties such as the electronic and thermal conductance of\nthese devices have been shown to oscillate symmetrically about zero with a\nperiod equal to one superconducting flux quantum, $\\Phi_o = h/2e$. However, the\nthermopower of these devices can oscillate symmetrically or antisymmetrically\ndepending on the geometry of the sample, a phenomenon not well understood\ntheoretically. Here we report on thermopower measurements of a double-loop\nAndreev interferometer where two Josephson currents in the normal metal wire\nmay be controlled independently. The amplitude and symmetries of the observed\nthermopower oscillations may help to illuminate the unexplained dependence of\noscillation symmetry on sample geometry.",
        "positive": "Quantum Oscillations from Fermi Sea: Quantum oscillations are conventionally understood to arise from the Fermi\nlevel; hence, they are considered to be a proof of the existence of an\nunderlying Fermi surface. In this article, we show that in certain situations\nquantum oscillations can also arise from inside the Fermi sea. We establish\nthis analytically, supporting it with numerical calculations. Possible\nscenarios where such unusual behavior can occur are pointed out. In particular,\nin strongly particle-hole asymmetric insulators, models of which have been\nrecently used in the context of the topological Kondo insulator SmB$_6$, we\nshow that the oscillations arise from inside the filled band, and are not\nrelated to the gap."
    },
    {
        "anchor": "Photo-induced spin filtering in a double quantum dot: We investigate the spin-resolved electron dynamics in a double quantum dot\ndriven by ultrafast asymmetric electromagnetic pulses. Using a analytical model\nwe show that applying an appropriate pulse sequence allows to control\ncoherently the spin degree of freedom on the femtosecond time scale. It can be\nachieved that the spin-up state is localized in a selected quantum dot while\nthe spin-down state remains in the other dot. We show that this photo-induced\nspin-dependent separation can be maintained for a desired period of time.",
        "positive": "Statistical exchange-coupling errors and the practicality of scalable\n  silicon donor qubits: Recent experimental efforts have led to considerable interest in donor-based\nlocalized electron spins in Si as viable qubits for a scalable silicon quantum\ncomputer. With the use of isotopically purified $^{28}$Si and the realization\nof extremely long spin coherence time in single-donor electrons, the recent\nexperimental focus is on two-coupled donors with the eventual goal of a\nscaled-up quantum circuit. Motivated by this development, we simulate the\nstatistical distribution of the exchange coupling $J$ between a pair of donors\nunder realistic donor placement straggles, and quantify the errors relative to\nthe intended $J$ value. With $J$ values in a broad range of donor-pair\nseparation ($5<|\\mathbf{R}|<60$ nm), we work out various cases systematically,\nfor a target donor separation $\\mathbf{R}_0$ along the [001], [110] and [111]\nSi crystallographic directions, with $|\\mathbf{R}_0|=10, 20$ or 30 nm and\nstandard deviation $\\sigma_R=1, 2, 5$ or 10 nm. Our extensive theoretical\nresults demonstrate the great challenge for a prescribed $J$ gate even with\njust a donor pair, a first step for any scalable Si-donor-based quantum\ncomputer."
    },
    {
        "anchor": "Electric field effect on electron spin splitting in SiGe/Si quantum\n  wells: Effect of electric field on spin splitting in SiGe quantum wells (QWs) has\nbeen studied theoretically. Microscopical calculations of valley and spin\nsplittings are performed in the effective $sp^3d^5s^*$ tight-binding model. The\nsplittings oscillate as a function of the QW width due to inter-valley\nreflection of the electron wave off the interfaces. In accordance with the\nsymmetry considerations additional electric-field-induced terms appear in the\nelectron spin-dependent Hamiltonian. The oscillations of splitting are\nsuppressed in rather low electric fields. The tight-binding calculations have\nbeen analyzed by using the envelope function approach extended to asymmetrical\nQWs.",
        "positive": "Layer Hall counterflow as a model probe of magic-angle twisted bilayer\n  graphene: The recent constructions of flat moir\\'e minibands in specifically twisted\nmultilayer graphene and twisted transition metal dichalcogenides (TMDs) have\nfacilitated the observation of strong correlations with a convenient\ntunability. These correlations in flat bands result in the band dispersion\nheavily influenced by carrier densities, leading to filling-dependent\nquasiparticle band renormalizations. Particularly, in magic-angle twisted\nbilayer graphene (MATBG), the band structure--including the quasiparticle\nenergy and wavefunction--is crucial in understanding the correlated properties.\nPrevious theoretical studies have demonstrated the presence of a\ntime-reversal-even charge Hall counterflow in response to a direct current (DC)\nelectric field in twisted bilayers as chiral structures. In this study, we show\nthat such layer Hall counterflow can serve as a sensitive probe for MATBG model\nparameters, which are currently ambiguous as a result of unavoidable structural\nrelaxation and twist-angle disorder. We present the layer Hall counterflow and\nthe associated in-plane magnetization for three different MATBG continuum\nmodels, based on which many-body interacting models have been widely applied to\nstudy strong correlations in MATBG. At the single-particle level, our findings\nindicate notable differences in layer-projected Hall conductivity, both in\nmagnitude and sign, between different MATBG continuum models. Furthermore, our\nself-consistent Hartree calculations, performed on each of these\nsingle-particle continuum models, reveal renormalized layer-projected Hall\nconductivity by the self-consistent Hartree field."
    },
    {
        "anchor": "Local density of states in disordered graphene: We study two lattice models, the honeycomb lattice (HCL) and a special square\nlattice (SQL), both reducing to the Dirac equation in the continuum limit. In\nthe presence of disorder (gaussian potential disorder and random vector\npotential), we investigate the behaviour of the density of states (DOS)\nnumerically and analytically. While an upper bound can be derived for the DOS\non the SQL at the Dirac point, which is also confirmed by numerical\ncalculations, no such upper limit exists for the HCL in the presence of random\nvector potential. A careful investigation of the lowest eigenvalues indeed\nindicate, that the DOS can possibly be divergent at the Dirac point on the HCL.\nIn spite of sharing a common continuum limit, these lattice models exhibit\ndifferent behaviour.",
        "positive": "A mesoscopic ring as a XNOR gate: An exact result: We describe XNOR gate response in a mesoscopic ring threaded by a magnetic\nflux $\\phi$. The ring is attached symmetrically to two semi-infinite\none-dimensional metallic electrodes and two gate voltages, viz, $V_a$ and\n$V_b$, are applied in one arm of the ring which are treated as the inputs of\nthe XNOR gate. The calculations are based on the tight-binding model and the\nGreen's function method, which numerically compute the conductance-energy and\ncurrent-voltage characteristics as functions of the ring-to-electrode coupling\nstrength, magnetic flux and gate voltages. Our theoretical study shows that,\nfor a particular value of $\\phi$ ($=\\phi_0/2$) ($\\phi_0=ch/e$, the elementary\nflux-quantum), a high output current (1) (in the logical sense) appears if both\nthe two inputs to the gate are the same, while if one but not both inputs are\nhigh (1), a low output current (0) results. It clearly exhibits the XNOR gate\nbehavior and this aspect may be utilized in designing an electronic logic gate."
    },
    {
        "anchor": "Stacking-engineered ferroelectricity in bilayer boron nitride: 2D ferroelectrics with robust polarization down to atomic thicknesses provide\nnovel building blocks for functional heterostructures. Experimental reports,\nhowever, remain scarce because of the requirement of a layered polar crystal.\nHere, we demonstrate a rational design approach to engineering 2D\nferroelectrics from a non-ferroelectric parent compound via employing van der\nWaals assembly. Parallel-stacked bilayer boron nitride is shown to exhibit\nout-of-plane electric polarization that reverses depending on the stacking\norder. The polarization switching is probed via the resistance of an\nadjacently-stacked graphene sheet. Furthermore, twisting the boron nitride\nsheets by a small-angle changes the dynamics of switching due to the formation\nof moir\\'e ferroelectricity with staggered polarization. The ferroelectricity\npersists to room temperature while keeping the high mobility of graphene,\npaving the way for potential ultrathin nonvolatile memory applications.",
        "positive": "Robustness of quantum Hall interferometry: Fabry-P\\'{e}rot interferometry has emerged as a tool to probe anyon\nstatistics in the quantum Hall effect. The interference phase is interpreted as\na combination of a quantized statistical phase and an Aharonov-Bohm phase,\nproportional to the device area and the charge of the anyons propagating along\nthe device edge. This interpretation faces two challenges. First, the edge\nstates have a finite width and hence the device area is ill-defined. Second,\nmultiple localized anyons may be present in states that overlap with the edge,\nand it may not be clear whether a second anyon traveling along the edge will go\ninside or outside the region with a localized anyon and therefore whether or\nnot it should pick up a statistical phase. We show how one may overcome both\nchallenges. In a case where only one chiral edge mode passes through the\nconstrictions defining the interferometer, as when electrons in a constriction\nare in a Laughlin state with $\\nu=1/(2n+1)$ or the integer state at $\\nu=1$, we\nshow that the interference phase can be directly related to the total electron\ncharge contained in the interferometer. This holds for arbitrary\nelectron-electron interactions and holds even if the bulk of the interferometer\nhas a higher electron density than the region of the constrictions. In contrast\nto the device area or to the number of anyons inside a propagating edge\nchannel, the total charge is well-defined. We examine, at the microscopic\nlevel, how the relation between charge and phase is maintained when there is a\nsoft confining potential and disorder near the edge of the interferometer, and\nwe discuss briefly the complications that can occur when multiple chiral modes\ncan pass through the constriction."
    },
    {
        "anchor": "Massless Dirac fermions in III-V semiconductor quantum wells: We report on the clear evidence of massless Dirac fermions in two-dimensional\nsystem based on III-V semiconductors. Using a gated Hall bar made on a\nthree-layer InAs/GaSb/InAs quantum well, we restore the Landau levels fan chart\nby magnetotransport and unequivocally demonstrate a gapless state in our\nsample. Measurements of cyclotron resonance at different electron\nconcentrations directly indicate a linear band crossing at the $\\Gamma$ point\nof Brillouin zone. Analysis of experimental data within analytical Dirac-like\nHamiltonian allows us not only determing velocity $v_F=1.8\\cdot10^5$ m/s of\nmassless Dirac fermions but also demonstrating significant non-linear\ndispersion at high energies.",
        "positive": "Towards tunable graphene phononic crystals: Phononic crystals (PnCs) are artificially patterned media exhibiting bands of\nallowed and forbidden zones for phonons. Many emerging applications of PnCs\nfrom solid-state simulators to quantum memories could benefit from the\non-demand tunability of the phononic band structure. Here, we demonstrate the\nfabrication of suspended graphene PnCs in which the phononic band structure is\ncontrolled by mechanical tension applied electrostatically. We show signatures\nof a mechanically tunable phononic band gap. The experimental data supported by\nsimulation suggest a phononic band gap at 28$-$33 MHz in equilibrium, which\nupshifts by 9 MHz under a mechanical tension of 3.1 Nm$^{-1}$. This is an\nessential step towards tunable phononics paving the way for more experiments on\nphononic systems based on 2D materials."
    },
    {
        "anchor": "Collective modes of CP(3) Skyrmion crystals in quantum Hall ferromagnets: The two-dimensional electron gas in a bilayer quantum Hall system can sustain\nan interlayer coherence at filling factor nu=1 even in the absence of tunneling\nbetween the layers. This system has low-energy charged excitations which may\ncarry textures in real spin or pseudospin. Away from filling factor nu =1 a\nfinite density of these is present in the ground state of the 2DEG and forms a\ncrystal. Depending on the relative size of the various energy scales, such as\ntunneling (Delta_SAS), Zeeman coupling (Delta_Z) or electrical bias (Delta_b),\nthese textured crystal states can involve spin, pseudospin, or both\nintertwined. In this article, we present a comprehensive numerical study of the\ncollective excitations of these textured crystals using the GRPA. For the pure\nspin case, at finite Zeeman coupling the state is a Skyrmion crystal with a\ngapless phonon mode, and a separate Goldstone mode that arises from a broken\nU(1) symmetry. At zero Zeeman coupling, we demonstrate that the constituent\nSkyrmions break up, and the resulting state is a meron crystal with 4 gapless\nmodes. In contrast, a pure pseudospin Skyrme crystal at finite tunneling has\nonly the phonon mode. For Delta_SAS=0, the state evolves into a meron crystal\nand supports an extra gapless U(1) mode in addition to the phonon. For a CP(3)\nSkyrmion crystal, we find a U(1) gapless mode in the presence of the\nsymmetry-breaking fields. In addition, a second mode with a very small gap is\npresent in the spectrum.",
        "positive": "Visible-frequency metasurfaces for broadband anomalous reflection and\n  high-efficiency spectrum splitting: Ultrathin metasurfaces have recently emerged as promising materials to enable\nnovel, flat optical components and surface-confined, miniature photonic\ndevices. However, experimental realization of high-performance metasurfaces at\nvisible frequencies has been a significant challenge due to high plasmonic\nlosses and difficulties in high-uniformity nanofabrication. Here, we propose a\nhighly-efficient yet simple metasurface design comprising of single gradient\nantenna as unit cell. We demonstrate visible broadband (450 - 850 nm) anomalous\nreflection and spectrum splitting with 85% conversion efficiency. Average power\nratio of anomalous reflection to the strongest diffraction was calculated to be\n~ 103 and measured to be ~ 10. The anomalous reflected photons and spectrum\nsplitting performance have been visualized using CCD and characterized using\nangle-resolved measurement setup. Metasurface design proposed here is a clear\ndeparture from conventional metasurfaces utilizing multiple, anisotropic\nresonators, and could enable high-efficiency, broadband metasurfaces for\nachieving directional emitters, polarization/spectrum splitting surfaces for\nspectroscopy and photovoltaics."
    },
    {
        "anchor": "Curvature induced magnonic crystal in nanowires: A new type of magnonic crystals, curvature induced ones, is realized in\nferromagnetic nanowires with periodically deformed shape. A magnon band\nstructure of such crystal is fully determined by its curvature: the developed\ntheory is well confirmed by simulations. An application to nanoscale spintronic\ndevises with the geometrically tunable parameters is proposed, namely, to\nfilter elements.",
        "positive": "Revealing the Charge Density Wave Proximity Effect in Graphene on\n  1T-TaS2: Proximity effect is a very powerful approach and has been widely applied to\ninduce electron correlations such as: superconductivity, magnetism and\nspin-orbit effects at the interface of heterostructure quantum materials.\nHowever, proximity induced charge density wave (CDW) state has remained\nelusive. We report the first observation of a novel proximity induced CDW\nwithin a graphene layer that is deposited on 1T-TaS2 crystal. By using scanning\ntunneling microscopy and spectroscopy to probe the interface of the\ngraphene/1T-TaS2 heterostructure together with theoretical modeling, we show\nthat the interactions between the Dirac-like carriers in graphene and the\ncorrelated electrons in 1T-TaS2 induce a periodic charge density modulation\nwithin graphene and modify the band structure at the surface of 1T-TaS2,\nresulting in a 7.5% reduction of its gap size. Our results provide a new\nplatform to manipulate the electron charge correlations in heterostructures."
    },
    {
        "anchor": "Magneto-optical conductivity in a topological insulator: Adding a small subdominant quadratic in momentum term to a dominant linear\nDirac dispersion curve affects conduction and valence band differently and\nleads to an hourglass-like structure for energy as a function of momentum. This\napplies to the protected surface states in topological insulators. The energies\nof the conduction and valence band Landau levels are also different and this\nleads to the splitting of optical absorption lines produced by the magnetic\nfield, which acquire a two peak structure. It also changes the peaks in the\nimaginary part of the Hall conductivity into two distinct contributions of\nopposite signs. The real part of the circularly polarized optical conductivity\nhowever retains its single peak structure but the peaks in right and left\nhandedness case are shifted in energy with respect to each other in contrast to\nthe pure Dirac case. The magnitude of the semiclassical cyclotron frequency is\nsignificantly modified by the presence of a mass term as is its variation with\nvalue of the chemical potential $\\mu$. Its optical spectral weight is found to\ndecrease with increasing $\\mu$ rather than increase as it does in the pure\nDirac limit.",
        "positive": "Electronic transmission through AB-BA domain boundary in bilayer\n  graphene: We study the electron transmission through the domain boundary on bilayer\ngraphene separating AB and BA stacking regions. Using the effective continuum\nmodel, we calculate the electron transmission probability as a function of the\nelectron energy and the incident angle, for several specific boundary\nstructures. The transmission strongly depends on the crystallographic direction\nof the boundary and also on the atomic configuration inside. At the low energy,\nthe boundary is either insulating or highly transparent depending on the\nstructure. In insulating cases, the transmission sharply rises when the Fermi\nenergy is increased to a certain level, suggesting that the electric current\nthrough the boundary can be controlled by the field effect. The boundary\nparallel to the zigzag direction generally have different transmission\nproperties between the two different valleys, and this enables to generate the\nvalley polarized current in a certain configuration. We show that those\ncharacteristic features can be qualitatively explained by the transverse\nmomentum conservation in the position-dependent band structure in the\nintermediate region."
    },
    {
        "anchor": "Valley-based FETs in graphene: An analogue of the Datta-Das spin FET is investigated, which is all-graphene\nand based on the valley degree of freedom of electrons / holes. The \"valley\nFET\" envisioned consists of a quantum wire of gapped graphene (channel)\nsandwiched between two armchair graphene nanoribbons (source and drain), with\nthe following correspondence to the spin FET: valley (K and K') \\leftrightarrow\nspin (up and down), armchair graphene nanoribbons \\leftrightarrow ferromagnetic\nelectrodes, graphene quantum wire \\leftrightarrow semiconductor quantum wire,\nvalley-orbit interaction \\leftrightarrow Rashba spin-orbit interaction. The\ndevice works as follows. The source (drain) injects (detects) carriers in a\nspecific valley polarization. A gate electric field is applied to the channel\nand modulates the valley polarization of carriers due to the valley-orbit\ninteraction, thus controlling the amount of current collected at the drain. The\nvalley FET is characterized by: i) smooth interfaces between electrodes and the\nchannel, ii) strong valley-orbit interaction for electrical control of drain\ncurrent, and iii) vanishing interband valley-flip scattering. By its analogy to\nthe spin FET, the valley FET provides a potential framework to develop\nlow-power FETs for graphene-based nanoelectronics.",
        "positive": "Surface resonance of the (2$\\times$1) reconstructed lanthanum hexaboride\n  (001)-cleavage plane: a combined STM and DFT study: We performed a combined study of the (001)-cleavage plane of lanthanum\nhexaboride (LaB$_\\text{6}$) using scanning tunneling microscopy (STM) and\ndensity functional theory (DFT). Experimentally, we found a (2$\\times$1)\nreconstructed surface on a local scale. The reconstruction is only short-range\nordered and tends to order perpendicularly to step edges. At larger distances\nfrom surface steps, the reconstruction evolves to a labyrinth-like pattern.\nThese findings are supported by low-energy electron diffraction (LEED)\nexperiments. Slab calculations within the framework of DFT shows that the\natomic structure consists of parallel lanthanum chains on top of boron\noctahedra. Scanning tunneling spectroscopy (STS) shows a prominent spectral\nfeature at -0.6 eV. Using DFT, we identify this structure as a surface\nresonance of the (2$\\times$1) reconstructed LaB$_\\text{6}$ (100)-surface which\nis dominated by boron dangling bond-states and lanthanum d-states."
    },
    {
        "anchor": "Frequency dependent third cumulant of current in diffusive conductors: We calculate the frequency dispersion of the third cumulant of current in\ndiffusive-metal contacts. The cumulant exhibits a dispersion at the inverse\ntime of diffusion across the contact, which is typically much smaller than the\ninverse $RC$ time. This dispersion is much more pronounced in the case of\nstrong electron-electron scattering than in the case of purely elastic\nscattering because of a different symmetry of the relevant second-order\ncorrelation functions.",
        "positive": "Eu ions and copper selenide nanoparticles within silica sol-gel matrices: The sol-gel technique was developed for preparation of silica glasses doped\nwith europium and copper chalcogenide nanoparticles. A synthesis of copper\ncompounds proceeded within the solid matrix at the different steps of the\nprocess, and features of final products can be controlled by the precursor\ncomposition and heat treatment conditions. Eu3+-ions within the silica matrix\nserves as a luminescent probe sensitive to the environment and a tool for\nstudies of energy transfer between different absorption and emission centers\nwith efficient light absorption in nanoparticles and emission by Eu3+."
    },
    {
        "anchor": "Unexpectedly Large Tunability of Lattice Thermal Conductivity of\n  Monolayer Silicene via Mechanical Strain: Strain engineering is one of the most promising and effective routes toward\ncontinuously tuning the electronic and optic properties of materials, while\nthermal properties are generally believed to be insensitive to mechanical\nstrain. In this paper, the strain-dependent thermal conductivity of monolayer\nsilicene under uniform bi-axial tension is computed by solving the phonon\nBoltzmann transport equation with force constants extracted from\nfirst-principles calculations. Unlike the commonly believed understanding that\nthermal conductivity only slightly decreases with increased tensile strain for\nbulk materials, it is found that the thermal conductivity of silicene first\nincreases dramatically with strain and then slightly decreases when the applied\nstrain increases further. At a tensile strain of 4%, the highest thermal\nconductivity is found to be about 7.5 times that of unstrained one. Such an\nunusual strain dependence is mainly attributed to the dramatic enhancement in\nthe acoustic phonon lifetime. Such enhancement plausibly originates from the\nflattening of the buckling of the silicene structure upon stretching, which is\nunique for silicene as compared with other common two-dimensional materials.\nOur findings offer perspectives of modulating the thermal properties of\nlow-dimensional structures for applications such as thermoelectrics, thermal\ncircuits, and nanoelectronics.",
        "positive": "Phase Dependent Thermopower in Andreev Interferometers: We report measurements of the thermopower S of mesoscopic Andreev\ninterferometers, which are hybrid loops with one arm fabricated from a\nsuperconductor (Al), and one arm from a normal metal (Au). S depends on the\nphase of electrons in the interferometer, oscillating as a function of magnetic\nflux with a period of one flux quantum (= h/2e). The magnitude of S increases\nas the temperature T is lowered, reaching a maximum around T = 0.14 K, and\ndecreases at lower temperatures. The symmetry of S oscillations with respect to\nmagnetic flux depends on the topology of the sample."
    },
    {
        "anchor": "Validation of tight-binding model in system of two semiconductor\n  single-electron lines coupled capacitively by Schroedinger formalism: Validation of tight-binding model is given basing on two single-electron\nlines coupled perturbatively electrostatically in Schroedinger formalism.\nScheme for conversion of quantum information from eigenenergy qubits to\nposition based qubits is given. The procedure for determination of system\nground is presented. Additional extension schemes of two coupled\nsingle-electron lines in case of Rabi oscillations occurring in each position\nbased qubits are given.",
        "positive": "Fundamental Optical Processes in Armchair Carbon Nanotubes: We have used post-synthesis separation methods based on density gradient\nultracentrifugation and DNA-based ion-exchange chromatography to produce\naqueous suspensions strongly enriched in armchair nanotubes for spectroscopic\nstudies. Through resonant Raman spectroscopy of the radial breathing mode\nphonons, we provide macroscopic and unambiguous evidence that density gradient\nultracentrifugation can enrich armchair nanotubes. Furthermore, using\nconventional, optical absorption spectroscopy in the near-infrared and visible\nrange, we show that interband absorption in armchair nanotubes is strongly\nexcitonic. Lastly, by examining the G-band mode in Raman spectra, we determine\nthat observation of the broad, lower frequency (G^{-}) feature is a result of\nresonance with non-armchair \"metallic\" nanotubes. These findings regarding the\nfundamental optical absorption and scattering processes in metallic carbon\nnanotubes lay the foundation for further spectroscopic studies to probe\nmany-body physical phenomena in one dimension."
    },
    {
        "anchor": "Extra Spin-Wave mode in Quantum Hall systems. Beyond the Skyrmion Limit: We report on the observation of a new spin mode in a quantum Hall system in\nthe vicinity of odd electron filling factors under experimental conditions\nexcluding the possibility of Skyrmion excitations. The new mode having\npresumably zero energy at odd filling factors emerges at small deviations from\nodd filling factors and couples to the spin-exciton. The existence of an extra\nspin mode assumes a nontrivial magnetic order at partial fillings of Landau\nlevels surrounding quantum Hall ferromagnets other then the Skyrmion crystal.",
        "positive": "Reflection and absorption of QWs irradiated by light pulses in a strong\n  magnetic field: It has been shown that the non-sinusoidal character oscillations appear in\nthe transmitted, reflected and absorbed light fluxes when light pulses\nirradiate a semiconductor quantum well (QW), containing a set of a large number\nof the equidistant energy levels of electronic excitations. The oscillation\namplitude is comparable to the flux values for the short pulses, duration of\nwhich \\gamma_l^{-1} \\leq \\hbar/\\Delta E. A damping echo of the exciting pulse\nappears through the time intervals 2\\pi\\hbar/\\Delta E in the case of the very\nshort light pulses \\gamma_l^{-1}\\ll \\hbar/\\Delta E. Symmetrical and\nasymmetrical pulses with a sharp front have been considered. Our theory is\napplicable for the narrow QWs in a strong magnetic field, when the equidistant\nenergy levels correspond to the electron-hole pairs with different Landau\nquantum numbers."
    },
    {
        "anchor": "Kondo effect with non collinear polarized leads: a numerical\n  renormalization group analysis: The Kondo effect in quantum dots attached to ferromagnetic leads with general\npolarization directions is studied combining poor man scaling and Wilson's\nnumerical renormalization group methods. We show that polarized electrodes will\nlead in general to a splitting of the Kondo resonance in the quantum dot\ndensity of states except for a small range of angles close to the antiparallel\ncase. We also show that an external magnetic field is able to compensate this\nsplitting and restore the unitary limit. Finally, we study the electronic\ntransport through the device in various limiting cases.",
        "positive": "Synthetic magnetism for solitons in optomechanical array: We propose a synthetic magnetism to generate and to control solitonic waves\nin $\\rm{1D}-$optomechanical array. Each optomechanical cavity in the array\ncouples to its neighbors through photon and phonon coupling. We create the\nsynthetic magnetism by modulating the phonon hopping rate through a modulation\nfrequency, and a modulation phase between resonators at different sites. When\nthe synthetic magnetism effect is not taken into account, the mechanical\ncoupling play a scrucial role of controlling and switching the waves from\nbright to dark solitons, and it even induces rogue wave-like a shape in the\narray. For enough mechanical coupling strength, the system enters into a strong\ncoupling regime through splitting/crossing of solitonic waves leading to\nmultiple waves propagation in the array. Under the synthetic magnetism effect,\nthe phase of the modulation enables a good control of the wave propagation, and\nit also switches soliton shape from bright to dark, and even induces rogue\nwaves as well. Similarly to the mechanical coupling, the synthetic magnetism\noffers another flexible way to generate plethora of solitonic waves for\nspecific purposes. This work opens new avenues for optomechanical platforms and\nsheets light on their potentiality of controlling and switching solitonic waves\nbased on synthetic magnetism."
    },
    {
        "anchor": "Field-driven collapsing dynamics of skyrmions in magnetic multilayers: Magnetic skyrmions are fascinating topological particle-like textures\npromoted by a trade-off among interfacial properties (perpendicular anisotropy\nand Dzyaloshinskii-Moriya interaction (DMI)) and dipolar interactions.\nDepending on the dominant interaction, complex spin textures, including pure\nN\\'eel and hybrid skyrmions have been observed in multilayer heterostructures.\nA quantification of these different spin textures typically requires a\ndepth-reoslved magnetic imaging or scattering techniques. In the present work,\nwe will show qualitatively different collapsing dynamics for pure N\\'eel and\nhybrid skyrmions induced by a perpendicular magnetic field in two\nrepresentative systems, [Pt/Co/Ir]15 and [Ta/CoFeB/MgO]15 multilayers.\nSkyrmions in the former stack undergo two morphological transitions, upon\nreversing the perpendicular field direction. Skyrmions in [Ta/CoFeB/MgO]15\nmultilayers exhibit a continuous transition, which is mainly linked to a\nreversible change of the skyrmion size. A full micromagnetic phase diagram is\npresented to identify these two collapsing mechanisms as a function of material\nparameters. Since the two distinct collapsing dynamics rely on the detailed\nlayer-dependent spin structures of skyrmions, they could be used as potential\nfingerprints for identifying the skyrmion type in magnetic multilayers. Our\nwork suggests the employment of pure and hybrid skyrmions for specific\napplications, due to the strong correlation between the skyrmion dynamics and\n3-dimentional spin profiles.",
        "positive": "Non-equilibrium Green's function predictions of band tails and band gap\n  narrowing in III-V semiconductors and nanodevices: High-doping induced Urbach tails and band gap narrowing play a significant\nrole in determining the performance of tunneling devices and optoelectronic\ndevices such as tunnel field-effect transistors (TFETs), Esaki diodes and\nlight-emitting diodes. In this work, Urbach tails and band gap narrowing values\nare calculated explicitly for GaAs, InAs, GaSb and GaN as well as ultra-thin\nbodies and nanowires of the same. Electrons are solved in the non-equilibrium\nGreen's function method in multi-band atomistic tight binding. Scattering on\npolar optical phonons and charged impurities is solved in the self-consistent\nBorn approximation. The corresponding nonlocal scattering self-energies as well\nas their numerically efficient formulations are introduced for ultra-thin\nbodies and nanowires. Predicted Urbach band tails and conduction band gap\nnarrowing agree well with experimental literature for a range of temperatures\nand doping concentrations. Polynomial fits of the Urbach tail and band gap\nnarrowing as a function of doping are tabulated for quick reference."
    },
    {
        "anchor": "Scattering theory of topological phases in discrete-time quantum walks: One-dimensional discrete-time quantum walks show a rich spectrum of\ntopological phases that have so far been exclusively analysed in momentum\nspace. In this work we introduce an alternative approach to topology which is\nbased on the scattering matrix of a quantum walk, adapting concepts from\ntime-independent systems. For gapped quantum walks, topological invariants at\nquasienergies 0 and {\\pi} probe directly the existence of protected boundary\nstates, while quantum walks with a non-trivial quasienergy winding have a\ndiscrete number of perfectly transmistting unidirectional modes. Our\nclassification provides a unified framework that includes all known types of\ntopology in one dimensional discrete-time quantum walks and is very well suited\nfor the analysis of finite size and disorder effects. We provide a simple\nscheme to directly measure the topological invariants in an optical quantum\nwalk experiment.",
        "positive": "Bulk-Fermi-Arc Transition Induced Large Photogalvanic Effect in Weyl\n  Semimetals: The surface Fermi arc, as a hallmark of Weyl semimetals (WSMs), has been well\nknown in current research, but it remains a challenge to unveil novel phenomena\nassociated with the Fermi arc. Here, we predict a heretofore unrecognized\nprocess in WSMs, namely, the photoinduced transition between the bulk states\nand the Fermi arc. We find this process is significant and can lead to a large\neffective three-dimensional shift current on the boundaries with the Fermi arc\nin wide terahertz range. Moreover, due to the low symmetry of the boundaries,\nthe surface photogalvanic effect predicted here can appear in a large class of\nWSMs that do not have bulk shift current. Hence, our work not only unveils a\nhidden photogalvanic effect in WSMs but also suggests that all the WSMs are\npromising material candidates for developing efficient terahertz\nphotodetectors."
    },
    {
        "anchor": "Anomalous topological edge states in non-Hermitian piezophononic media: The bulk-boundary or bulk-edge correspondence is a principle relating surface\nconfined states to the topological classification of the bulk. By combining\nnon-Hermitian ingredients in terms of gain or loss with media that violate\nreciprocity, an unconventional non-Bloch bulk-boundary correspondence leads to\nunusual localization of bulk states at boundaries$-$a phenomenon coined\nnon-Hermitian skin effect. Here we \\textcolor{black}{numerically} employ the\nacoustoelectric effect in electrically biased and layered piezophononic media\nas a solid framework for non-Hermitian and nonreciprocal topological mechanics\nin the MHz regime. Thanks to a non-Hermitian skin effect for mechanical\nvibrations, we find that the bulk bands of finite systems are highly sensitive\nto the type of crystal termination, which indicates a failure of using\ntraditional Bloch bands to predict the wave characteristics. More surprisingly,\nwhen reversing the electrical bias, we unveil how topological edge and bulk\nvibrations can be harnessed either at the same or opposite interface. Yet,\nwhile bulk states are found to display this unconventional skin effect, we\nfurther discuss how in-gap edge states in the same instant, counterintuitively\nare able to delocalize along the entire layered medium. We foresee that our\npredictions will stimulate new avenues in echo-less ultrasonics based on exotic\nwave physics.",
        "positive": "Ab-Initio Theory of Moir\u00e9 Superlattice Bands in Layered\n  Two-Dimensional Materials: When atomically thin two-dimensional (2D) materials are layered they often\nform incommensurate non-crystalline structures that exhibit long-period moir{\\'\ne} patterns when examined by scanning probes. In this paper we present an\napproach which uses information obtained from {\\it ab initio} calculations\nperformed on short-period crystalline structures to derive effective\nHamiltonians that are able to efficiently describe the influence of the moir{\\'\ne} pattern superlattices on electronic properties. We apply our approach to the\ncases of graphene on graphene (G/G) and graphene on hexagonal boron nitride\n(G/BN), deriving explicit effective Hamiltonians that have the periodicity of\nthe moir{\\' e} pattern and can be used to calculate electronic properties of\ninterest for arbitrary twist angles and lattice constants."
    },
    {
        "anchor": "Applications of random matrix theory to condensed matter and optical\n  physics: This is a cursory overview of applications of concepts from random matrix\ntheory (RMT) to quantum electronics and classical & quantum optics. The\nemphasis is on phenomena, predicted or explained by RMT, that have actually\nbeen observed in experiments on quantum wires, quantum dots, disordered wave\nguides, and chaotic resonators. Topics considered include universal conductance\nfluctuations, weak localization and coherent backscattering, sub-Poissonian\nshot noise and open transmission channels, non-Gaussian conductance and\nthermopower distributions, mesoscopic superconductivity, grey-body radiation,\nand chaotic laser cavities.",
        "positive": "Impact of current paths on measurement of tunneling magnetoresistance\n  and spin torque critical current densities in GaMnAs-based magnetic tunnel\n  junctions: GaMnAs-based magnetic tunnel junction (MTJ) devices are characterized by\nin-plane and perpendicular-toplane magnetotransport at low temperatures.\nPerpendicular-to-plane transport reveals the typical tunneling magnetotransport\n(TMR) signal. Interestingly, a similar TMR signature is observed in the\nin-plane transport signal. Here, low-ohmic shunting of the MTJ by the top\ncontact results in significant perpendicular-to-plane current paths. This\neffect allows the determination of TMR ratios of MTJs based on a simplified\nin-plane measurement. However, the same effect can lead to an inaccurate\ndetermination of resistance area products and spin torque critical current\ndensities from perpendicular-to-plane magnetotransport experiments on MTJ\npillar structures."
    },
    {
        "anchor": "Anomalous thermospin effect in the low-buckled Dirac materials: A strong spin Nernst effect with nontrivial dependences on the carrier\nconcentration and electric field applied is expected in silicene and other\nlow-buckled Dirac materials. These Dirac materials can be considered as being\nmade of two independent electron subsystems of the two-component gapped Dirac\nfermions. For each subsystem the gap breaks a time-reversal symmetry and thus\nplays a role of an effective magnetic field. Accordingly, the standard Kubo\nformalism has to be altered by including the effective magnetization in order\nto satisfy the third law of thermodynamics. We explicitly demonstrate this by\ncalculating the magnetization and showing how the correct thermoelectric\ncoefficient emerges.",
        "positive": "Micro-SQUID technique for studying the temperature dependence of\n  switching fields of single nanoparticles: An improved micro-SQUID technique is presented allowing us to measure the\ntemperature dependence of the magnetisation switching fields of single\nnanoparticles well above the critical superconducting temperature of the SQUID.\nOur first measurements on 3 nm cobalt nanoparticle embedded in a niobium matrix\nare compared to the Neel Brown model describing the magnetisation reversal by\nthermal activation over a single anisotropy barrier."
    },
    {
        "anchor": "Few-electron artificial molecules formed by laterally coupled quantum\n  rings: We study the artificial molecular states formed in laterally coupled double\nsemiconductor nanorings by systems containing one, two and three electrons. An\ninterplay of the interring tunneling and the electron-electron interaction is\ndescribed and its consequences for the magnetization and charging properties of\nthe system are determined. It is shown that both the magnetic dipole moment\ngenerated by the double ring structure and the chemical potential of the system\nas function of the external magnetic field strongly depend on the number of\nelectrons and the interring barrier thickness. Both the magnetization and\nchemical potentials exhibit cusps at the magnetic fields inducing ground-state\nparity and / or spin transformations. The symmetry transformations are\ndiscussed for various tunnel coupling strengths: from rings coupled only\nelectrostatically to the limit of coalesced rings. We find that in the\nground-states for rings of different radii the magnetic field transfers the\nelectron charge from one ring to the other. The calculations are performed with\nthe configuration interaction method based on an approach of Gaussian functions\ncentered on a rectangular array of points covering the studied structure.\nElectron-electron correlation is also discussed.",
        "positive": "Phase-Charge Duality of a Josephson junction in a fluctuating\n  electromagnetic environment: We have measured the current-voltage characteristics of a single Josephson\njunction placed in a high impedance environment. The transfer of Cooper pairs\nthrough the junction is governed by overdamped quasicharge dynamics, leading to\nCoulomb blockade and Bloch oscillations. Exact duality exists to the standard\noverdamped phase dynamics of a Josephson junction, resulting in a dual shape of\nthe current-voltage characteristic, with current and voltage changing roles. We\ndemonstrate this duality with experiments which allow for a quantitative\ncomparison with a theory that includes the effect of fluctuations due to finite\ntemperature of the electromagnetic environment."
    },
    {
        "anchor": "Splitting of Andreev levels in a Josephson junction by spin-orbit\n  coupling: We consider the effect of spin-orbit coupling on the energy levels of a\nsingle-channel Josephson junction below the superconducting gap. We investigate\nquantitatively the level splitting arising from the combined effect of\nspin-orbit coupling and the time-reversal symmetry breaking by the phase\ndifference between the superconductors. Using the scattering matrix approach we\nestablish a simple connection between the quantum mechanical time delay matrix\nand the effective Hamiltonian for the level splitting. As an application we\ncalculate the distribution of level splittings for an ensemble of chaotic\nJosephson junctions. The distribution falls off as a power law for large\nsplittings, unlike the exponentially decaying splitting distribution given by\nthe Wigner surmise -- which applies for normal chaotic quantum dots with\nspin-orbit coupling in the case that the time-reversal symmetry breaking is due\nto a magnetic field.",
        "positive": "Combined large spin-splitting and one dimensional confinement in surface\n  alloys: We have found and characterized by angle-resolved photoelectron spectroscopy\n(ARPES) quasi-one dimensional spin-split states in chain-like surface alloys\nformed by large Z elements (Bi and Pb) at the Cu(110) surface. The ARPES\nresults are supported by first-principles relativistic calculations, which also\nconfirm the spin polarization of these states, characteristic of the\nRashba-Bychkov effect. The Fermi surface contours are open, but warped, as a\nresult of the interaction with the bulk Cu conduction band. This interaction\nintroduces a k dependence of the spin splitting perpendicular to the chains\ndirection. We have also investigated the influence of the atomic spin-orbit\nparameter in substitutional isostructural Bi_{1-x}Pb_{x} overlayers, and found\nthat the magnitude of the spin splitting can be continuously tuned as a\nfunction of stoichiometry."
    },
    {
        "anchor": "Transport Through a Quantum Dot with Electron-Phonon Interaction: We theoretically study the electrical transport properties of a single level\nquantum dot connected to two normal conducting leads, which is coupled to the\nlattice vibrations. We determine the current through the quantum dot in two\ndifferent situations: time-independent and time-averaged. In all situations we\nconsider three cases: when there is no electron-phonon interaction, when the\ndot electrons interact with optical phonons or when they interact with acoustic\nphonons. At finite temperatures we take into account the temperature dependence\nof the chemical potential. We treat the electron-phonon interaction by the\ncanonical transformation method. In the case of electron-longitudinal optical\nphonon interaction the spectrum contains a subpeak. In the case of\nelectron-acoustic phonon interaction the spectrum is continuous. In the\ntime-averaged situation many parasite peaks appear in the spectrum, due to the\nexternal time-modulation.",
        "positive": "Spatial mapping and analysis of graphene nanomechanical resonator\n  networks: Nanoelectromechanical (NEMS) resonator networks have drawn increasing\ninterest due to their potential applications in emergent behavior, sensing,\nphononics, and mechanical information processing. A challenge toward realizing\nthese large-scale networks is the ability to controllably tune and reconfigure\nthe collective, macroscopic properties of the network, which relies directly on\nthe development of methods to characterize the constituent NEMS resonator\nbuilding blocks and their coupling. In this work, we demonstrate a scalable\noptical technique to spatially map graphene NEMS networks and read out the\nfixed-frequency collective response as a single vector. Using the response\nvectors, we introduce an efficient algebraic approach to quantify the\nsite-specific elasticity, mass, damping, and coupling parameters of network\nclusters. We apply this technique to accurately characterize single uncoupled\nresonators and coupled resonator pairs by sampling them at just two\nfrequencies, and without the use of curve fitting or the associated a priori\nparameter estimates. Our technique may be applied to a range of classical and\nquantum resonator systems and fills in a vital gap for programming NEMS\nnetworks."
    },
    {
        "anchor": "Topological response in Weyl semimetals and the chiral anomaly: We demonstrate that topological transport phenomena, characteristic of Weyl\nsemimetals, namely the semi-quantized anomalous Hall effect and the chiral\nmagnetic effect (equilibrium magnetic-field-driven current), may be thought of\nas two distinct manifestations of the same underlying phenomenon, the chiral\nanomaly. We show that the topological response in Weyl semimetals is fully\ndescribed by a $\\theta$-term in the action for the electromagnetic field, where\n$\\theta$ is not a constant parameter, like e.g. in topological insulators, but\nis a field, which has a linear dependence on the space-time coordinates. We\nalso show that the $\\theta$-term and the corresponding topological response\nsurvive for sufficiently weak translational symmetry breaking perturbations,\nwhich open a gap in the spectrum of the Weyl semimetal, eliminating the Weyl\nnodes.",
        "positive": "Decoherence Dynamics of Complex Photon States in a Superconducting\n  Circuit: Quantum states inevitably decay with time into a probabilistic mixture of\nclassical states, due to their interaction with the environment and measurement\ninstrumentation. We present the first measurement of the decoherence dynamics\nof complex photon states in a condensed-matter system. By controllably\npreparing a number of distinct, quantum-superposed photon states in a\nsuperconducting microwave resonator, we show that the subsequent decay dynamics\ncan be quantitatively described by taking into account only two distinct decay\nchannels, energy relaxation and dephasing. Our ability to prepare specific\ninitial quantum states allows us to measure the evolution of specific elements\nin the quantum density matrix, in a very detailed manner that can be compared\nwith theory."
    },
    {
        "anchor": "Sound in a system of chiral one-dimensional fermions: We consider a system of one-dimensional fermions moving in one direction,\nsuch as electrons at the edge of a quantum Hall system. At sufficiently long\ntime scales the system is brought to equilibrium by weak interactions between\nthe particles, which conserve their total number, energy, and momentum. Time\nevolution of the system near equilibrium is described by hydrodynamics based on\nthe three conservation laws. We find that the system supports three sound\nmodes. In the low temperature limit one mode is a pure oscillation of particle\ndensity, analogous to the ordinary sound. The other two modes involve\noscillations of both particle and entropy densities. In the presence of\ndisorder, the first sound mode is strongly damped at frequencies below the\nmomentum relaxation rate, whereas the other two modes remain weakly damped.",
        "positive": "D.C. Josephson transport by quartets and other Andreev resonances in\n  superconducting bijunctions: Bijunctions are three-terminal Josephson junctions where three\nsuperconductors are connected by a single weak link made of a metallic region\nor of quantum dots. Biasing two of the superconductors with commensurate\nvoltages yields Andreev resonances that produce d.c. Josephson currents made of\ncorrelated Cooper pairs. For instance with applied voltages (0, V,-V), quartets\nformed by two entangled Cooper pairs are emitted by one reservoir towards the\ntwo others. Theory involving non-equilibrium Green's functions reveal the\nmicrosopic mechanism at play, e.g. multiple coherent Andreev reflections that\nprovide an energy-conserving and fully coherent channel. Recent experiments on\ndiffusive Aluminum-Copper bijunctions show transport anomalies that are\ninterpreted in terms of quartet resonances."
    },
    {
        "anchor": "Characterizing multi-mode nonlinear dynamics of nanomechanical\n  resonators: Mechanical nonlinearities dominate the motion of nanoresonators already at\nrelatively small oscillation amplitudes. Although single and coupled\ntwo-degrees-of-freedom models have been used to account for experimentally\nobserved nonlinear effects, it is shown that these models quickly deviate from\nexperimental findings when multiple modes influence the nonlinear response.\nHere, we present a nonlinear reduced-order modelling methodology based on FEM\nsimulations for capturing the global nonlinear dynamics of nanomechanical\nresonators. Our physics-based approach obtains the quadratic and cubic\nnonlinearities of resonators over a wide frequency range that spans 70 MHz. To\nqualitatively validate our approach, we perform experiments on a graphene\nnanodrum driven opto-thermally and show that the model can replicate diverse\nranges of nonlinear phenomena, including multi-stability, parametric resonance,\nand different internal resonances without considering any empirical nonlinear\nfitting parameters. By providing a direct link between microscopic geometry,\nmaterial parameters, and nonlinear dynamic response, we clarify the physical\nsignificance of nonlinear parameters that are obtained from fitting the\ndynamics of nanomechanical systems, and provide a route for designing devices\nwith desired nonlinear behaviour.",
        "positive": "Chiral light amplifier with pumped Weyl semimetals: Parallel electric and magnetic fields applied to Weyl semimetals pump axial\ncharge via the axial anomaly until balanced by intervalley relaxation. The\nresulting nonequilibrium steady state exhibits the chiral magnetic effect as\nwell as the anomalous Hall effect, which coupled with Maxwell's equations leads\nto unstable electromagnetic waves at low frequency and long wavelength. Here,\nwe show that such chiral magnetic instability manifests itself as anomalous\nreflectance of the surface of pumped Weyl semimetal. Depending on electric,\nchiral magnetic, and anomalous Hall conductivities, the reflectance is found to\nexceed unity in a finite range of frequency for a circularly polarized light\nincident along the direction of Weyl node separation."
    },
    {
        "anchor": "Direct Observation of the Reciprocity between Spin Current and Phonon\n  Interconversion: Spin current has emerged as a leading candidate for manipulation of spins in\na nano-magnet. We here experimentally show another utility of spin current viz.\nit can be used for generation of phonons. Within the same experimental setup,\nwe also demonstrate the inverse effect of generation of spin current by\nphonons. To demonstrate them, we measured the scattering-matrix of a two-port\ndevice with interdigital transducers as one port and array of Ni/Pt lines as\nsecond port on piezoelectric substrate. The off-diagonal elements which\ncorrespond to transmission between the ports, were found to have 180 degree\nrelative phase shift. The transmission of electrical signal from port 2 to 1\ncorresponds to generation of phonons from spin-current, while transmission from\nport 1 to 2 corresponds to the inverse effect. These results could be useful\nfor designing spin-current based gyrators.",
        "positive": "Zitterbewegung of electrons in quantum wells and dots in presence of an\n  in-plane magnetic field: We study the effect of an in-plane magnetic field on the zitterbewegung (ZB)\nof electrons in a semiconductor quantum well (QW) and in a quantum dot (QD)\nwith the Rashba and Dresselhaus spin-orbit interactions. We obtain a general\nexpression of the time-evolution of the position vector and current of the\nelectron in a semiconductor quantum well. The amplitude of the oscillatory\nmotion is directly related to the Berry connection in momentum space. We find\nthat in presence of the magnetic field the ZB in a quantum well does not vanish\nwhen the strengths of the Rashba and Dresselhaus spin-orbit interactions are\nequal. The in-plane magnetic field helps to sustain the ZB in quantum wells\neven at low value of $k_0 d$ (where $d$ is the width of the Gaussian wavepacket\nand $k_0$ is the initial wave vector). The trembling motion of an electron in a\nsemiconductor quantum well with high Lande g-factor (e.g. InSb) sustains over a\nlong time, even at low value of $k_0 d$. Further, we study the ZB of an\nelectron in quantum dots within the two sub-band model numerically. The\ntrembling motion persists in time even when the magnetic field is absent as\nwell as when the strengths of the SOI are equal. The ZB in quantum dots is due\nto the superposition of oscillatory motions corresponding to all possible\ndifferences of the energy eigenvalues of the system. This is an another example\nof multi-frequency ZB phenomenon."
    },
    {
        "anchor": "Onset of exciton-exciton annihilation in single layer black phosphorus: The exciton dynamics in monolayer black phosphorus is investigated over a\nvery wide range of photoexcited exciton densities using time resolved\nphotoluminescence. At low excitation densities, the exciton dynamics is\nsuccessfully described in terms of a double exponential decay. With increasing\nexciton population, a fast, non-exponential component develops as\nexciton-exciton annihilation takes over as the dominant recombination mechanism\nunder high excitation conditions. Our results identify an upper limit for the\ninjection density, after which exciton-exciton annihilation reduces the quantum\nyield, which will significantly impact the performance of light emitting\ndevices based on single layer black phosphorus.",
        "positive": "Effects of electron correlation on the photocurrent in quantum dot\n  infrared photodetectors: The effect of electron correlation on the photocurrent of self-assembled\nInAs/InGaAs quantum dot infrared photo-detector (QDIPs) is studied. It is found\nthat Coulomb interaction and level mixing in the many-body open system lead to\ndouble peaks associated with the intra-band transitions involving two lowest\nlevels of the quantum dot. Furthermore, the photocurrent is a nonlinear\nfunction of the steady-state carrier density and it displays a plateau due to\nCoulomb blockade."
    },
    {
        "anchor": "Feynman's Propagator Applied to Network Models of Localization: Network models of dirty electronic systems are mapped onto an interacting\nfield theory of lower dimensionality by intepreting one space dimension as\ntime. This is accomplished via Feynman's interpretation of anti-particles as\nparticles moving backwards in time. The method developed maps calculation of\nthe moments of the Landauer conductance onto calculation of correlation\nfunctions of an interacting field theory of bosons and fermions. The resulting\nfield theories are supersymmetric and closely related to the supersymmetric\nspin-chain representations of network models recently discussed by various\nauthors. As an application of the method, the two-edge Chalker-Coddington model\nis shown to be Anderson localized, and a delocalization transition in a related\ntwo-edge network model (recently discussed by Balents and Fisher) is studied by\ncalculation of the average Landauer conductance.",
        "positive": "Lighting up topological insulators: large surface photocurrents from\n  magnetic superlattices: The gapless surface states of topological insulators (TI) can potentially be\nused to detect and harvest low-frequency infrared light. Nonetheless, it was\nshown that significant surface photocurrents due to light with frequency below\nthe bulk gap are rather hard to produce. Here we demonstrate that a periodic\nmagnetic pattern added to the surface dramatically enhances surface\nphotocurrents in TI's. Moreover, the sensitivity of this set-up to the\nwavelength of the incident light can be optimized by tuning the geometry of the\nmagnetic pattern. The ability to produce substantial photocurrents on TI\nsurfaces from mid-range and far-infrared light could be used in photovoltaic\napplications, as well as for detection of micrometer wavelength radiation. For\nlight of wavelength greater than 15$\\mu$m we estimate that at room temperature,\na detector based on the effect we describe can have a specific detectivity as\nhigh as 10$^7$ cm$\\sqrt{\\text{Hz}}$/W (i.e. 10$^9$ Jones). The device can\ntherefore operate at much larger wavelengths than existing infrared detectors,\nwhile maintaining a comparable figure of merit.er wavelength radiation."
    },
    {
        "anchor": "Transport properties of 2D graphene containing structural defects: We propose an extensive report on the simulation of electronic transport in\n2D graphene in presence of structural defects. Amongst the large variety of\nsuch defects in sp$^2$ carbon-based materials, we focus on the Stone-Wales\ndefect and on two divacancy-type reconstructed defects. First, based on ab\ninitio calculations, a tight-binding model is derived to describe the\nelectronic structure of these defects. Then, semiclassical transport properties\nincluding the elastic mean free paths, mobilities and conductivities are\ncomputed using an order-N real-space Kubo-Greenwood method. A plateau of\nminimum conductivity ($\\sigma^{min}_{sc}= 4e^2/\\pi h$) is progressively\nobserved as the density of defects increases. This saturation of the decay of\nconductivity to $\\sigma^{min}_{sc}$ is associated with defect-dependent\nresonant energies. Finally, localization phenomena are captured beyond the\nsemiclassical regime. An Anderson transition is predicted with localization\nlengths of the order of tens of nanometers for defect densities around 1%.",
        "positive": "Theory of Spin Torque in a nanomagnet: We present a complete theory of the spin torque phenomena in a ultrasmall\nnanomagnet coupled to non-collinear ferromagnetic electrodes through tunnelling\njunctions. This model system can be described by a simple microscopic model\nwhich captures many physical effects characteristic of spintronics: tunneling\nmagneto resistance, intrinsic and transport induced magnetic relaxation,\ncurrent induced magnetization reversal and spin accumulation. Treating on the\nsame footing the magnetic and transport degrees of freedom, we arrive at a\nclosed equation for the time evolution of the magnetization. This equation is\nvery close to the Landau-Lifshitz-Gilbert equation used in spin valves\nstructures. We discuss how the presence of the Coulomb blockade phenomena and\nthe discretization of the one-body spectrum gives some additional features to\nthe current induced spin torque. Depending on the regime, the dynamic induced\nby the coupling to electrode can be viewed either as a spin torque or as a\nrelaxation process. In addition to the possibility of stabilizing uniform spin\nprecession states, we find that the system is highly hysteretic: up to three\ndifferent magnetic states can be simultaneously stable in one region of the\nparameter space (magnetic field and bias voltage).We also discuss how the\nmagneto-resistance can be used to provide additional information on the\nnon-equilibrium peaks present in the nanomagnet spectroscopy experiments."
    },
    {
        "anchor": "Exciton-phonon-scattering: A competition between bosonic and fermionic\n  nature of bound electron-hole pairs: The question of macroscopic occupation and spontaneous emergence of coherence\nfor exciton ensembles has gained renewed attention due to the rise of van der\nWaals heterostructures made of atomically thin semiconductors. The hosted\ninterlayer excitons exhibit nanosecond lifetimes, long enough to allow for\nexcitonic thermalization in time. Several experimental studies reported\nsignatures of macroscopic occupation effects at elevated exciton densities.\nWith respect to theory, excitons are composite particles formed by fermionic\nconstituents, and a general theoretical argument for a bosonic thermalization\nof an exciton gas beyond the linear regime is still missing. Here, we derive an\nequation for the phonon mediated thermalization at densities above the\nclassical limit, and identify which conditions favor the thermalization of\nfermionic or bosonic character, respectively. In cases where acoustic,\nquasielastic phonon scattering dominates the dynamics, our theory suggests that\ntransition metal dichalcogenide (TMDC) excitons might be bosonic enough to show\nbosonic thermalization behaviour and decreasing dephasing for increasing\nexciton densities. This can be interpreted as a signature of an emerging\ncoherence in the exciton ground state, and agrees well with the experimentally\nobserved features, such as a decreasing linewidth for increasing densities.",
        "positive": "Nonlinear circular valley photogalvanic effect: We develop a theory of circular photogalvanic effect in non-gyrotropic\ntwo-dimensional transition metal dichalcogenide monolayers under interband\noptical transitions. Oblique incidence of circularly-polarized electromagnetic\nfield or normal incidence of elliptically polarized electromagnetic field is\nassumed. In contrast to the linear-in-intensity conventional photogalvanic\neffect, the effect considered here arises in the second intensity order. The\neffect is conditioned by i) the predominant population of the valleys by the\ncircular in-plane electromagnetic field component and ii) the direct drift of\nthe photo-excited carriers by the linear-polarized in-plane electromagnetic\nfield component in the presence of trigonal valley asymmetry."
    },
    {
        "anchor": "Anomalous and normal dislocation modes in Floquet topological insulators: Electronic bands featuring nontrivial bulk topological invariant manifest\nthrough robust gapless modes at the boundaries, e.g., edges and surfaces. As\nsuch this bulk-boundary correspondence is also operative in driven quantum\nmaterials. For example, a suitable periodic drive can convert a trivial\ninsulator into a Floquet topological insulator (FTI) that accommodates\nnondissipative dynamic gapless modes at the interfaces with vacuum. Here we\ntheoretically demonstrate that dislocations, ubiquitous lattice defects in\ncrystals, can probe FTIs as well as unconventional $\\pi$-trivial insulator in\nthe bulk of driven quantum systems by supporting normal and anomalous modes,\nlocalized near the defect core. Respectively, normal and anomalous dislocation\nmodes reside at the Floquet zone center and boundaries. We exemplify these\noutcomes specifically for two-dimensional (2D) Floquet Chern insulator and\n$p_x+ip_y$ superconductor, where the dislocation modes are respectively\nconstituted by charged and neutral Majorana fermions. Our findings should be\ntherefore instrumental in probing Floquet topological phases in the\nstate-of-the-art experiments in driven quantum crystals, cold atomic setups,\nand photonic and phononic metamaterials through bulk topological lattice\ndefects.",
        "positive": "On the Dispersion Relation of Magnetoplasmons in a Planar Graphene-Based\n  Superlattice: The dispersion relation for magnetoplasmons in a planar superlattice with\nperiodically alternating regions of gapless and gapped modications of graphene\nhas been derived within the frame of the random-phase approximation. The\ncontribution of virtual transitions between the lower electron miniband and the\nupper hole miniband to the polarization operator has been taken into account in\naddition to the contribution of virtual intra-miniband transitions."
    },
    {
        "anchor": "Electron transport through an interacting region: The case of a\n  nonorthogonal basis set: The formula derived by Meir and Wingreen [Phys. Rev. Lett. {\\bf 68}, 2512\n(1992)] for the electron current through a confined, central region containing\ninteractions is generalized to the case of a nonorthogonal basis set. As in the\noriginal work, the present derivation is based on the nonequilibrium Keldysh\nformalism. By replacing the basis functions of the central region by the\ncorresponding elements of the dual basis, the lead- and central\nregion-subspaces become mutually orthogonal. The current formula is then\nderived in the new basis, using a generalized version of second quantization\nand Green's function theory to handle the nonorthogonality within each of the\nregions. Finally, the appropriate nonorthogonal form of the perturbation series\nfor the Green's function is established for the case of electron-electron and\nelectron-phonon interactions in the central region.",
        "positive": "Non-equilibrium fractional quantum Hall states visualized by optically\n  detected MRI: Using photoluminescence microscopy enhanced by MRI, we visualize in real\nspace both electron and nuclear polarization occurring in non-equilibrium FQH\nliquids. We observe stripe-like regions comprising FQH excited states which\ndiscretely form when the FQH liquid is excited by a source-drain current. These\nregions are topologically protected and deformable, and give rise to\nbidirectionally polarized nuclear spins as spin-resolved electrons flow across\ntheir boundaries."
    },
    {
        "anchor": "Irreducible Green Functions Method applied to nanoscopic systems: The equation of motion method (EOM) for Green functions is one of the tools\nused in the analysis of quantum dot system coupled with metallic and\nsuperconducting leads. We investigate modified EOM, based on differentiation of\ndouble-time temperature dependent Green functions both after primary time t and\nsecondary time t'. Our EOM approach allows us to obtain the Abrikosov-Suhl\nresonance both in the particle-hole symmetric case but also in the asymmetric\ncases. We will apply the irreducible Green functions technique to analyses the\nEOM for dot system. This method give a workable decoupling scheme breaking the\ninfinite set of Green function equations. We apply this technique for\ncalculating the density of the states and the differential conductance of\nsingle-level quantum dot with Coulomb repulsion attached to one metallic and\none superconducting leads (N-QD-SC). Our results are compared with the\nexperimental data and previous calculations.",
        "positive": "Valley addressable exciton-polaritons in atomically thin semiconductors: While conventional semiconductor technology relies on the manipulation of\nelectrical charge for the implementation of computational logic, additional\ndegrees of freedom such as spin and valley offer alternative avenues for the\nencoding of information. In transition metal dichalcogenide (TMD) monolayers,\nwhere spin-valley locking is present, strong retention of valley chirality has\nbeen reported for MoS$_2$, WSe$_2$ and WS$_2$ while MoSe$_2$ shows anomalously\nlow valley polarisation retention. In this work, chiral selectivity of MoSe$_2$\ncavity polaritons under helical excitation is reported with a polarisation\ndegree that can be controlled by the exciton-cavity detuning. In contrast to\nthe very low circular polarisation degrees seen in MoSe$_2$ exciton and trion\nresonances, we observe a significant enhancement of up to 7 times when in the\npolaritonic regime. Here, polaritons introduce a fast decay mechanism which\ninhibits full valley pseudospin relaxation and thus allows for increased\nretention of injected polarisation in the emitted light. A dynamical model\napplicable to cavity-polaritons in any TMD semiconductor, reproduces the\ndetuning dependence through the incorporation of the cavity-modified exciton\nrelaxation, allowing an estimate of the spin relaxation time in MoSe$_2$ which\nis an order of magnitude faster than those reported in other TMDs. The valley\naddressable exciton-polaritons reported here offer robust valley polarised\nstates demonstrating the prospect of valleytronic devices based upon TMDs\nembedded in photonic structures, with significant potential for\nvalley-dependent nonlinear polariton-polariton interactions."
    },
    {
        "anchor": "Shot noise suppression at room temperature in atomic-scale Au junctions: Shot noise encodes additional information not directly inferable from simple\nelectronic transport measurements. Previous measurements in atomic-scale metal\njunctions at cryogenic temperatures have shown suppression of the shot noise at\nparticular conductance values. This suppression demonstrates that transport in\nthese structures proceeds via discrete quantum channels. Using a high frequency\ntechnique, we simultaneously acquire noise data and conductance histograms in\nAu junctions at room temperature and ambient conditions. We observe noise\nsuppression at up to three conductance quanta, with possible indications of\ncurrent-induced local heating and $1/f$ noise in the contact region at high\nbiases. These measurements demonstrate the quantum character of transport at\nroom temperature at the atomic scale. This technique provides an additional\ntool for studying dissipation and correlations in nanodevices.",
        "positive": "Nodal Manifolds Bounded by Exceptional Points on Non-Hermitian Honeycomb\n  Lattices and Electrical-Circuit Realizations: Topological semimetals feature a diversity of nodal manifolds including nodal\npoints, various nodal lines and surfaces, and recently novel quantum states in\nnon-Hermitian systems have been arousing widespread research interests. In\ncontrast to Hermitian systems whose bulk nodal points must form closed\nmanifolds, it is fascinating to find that for non-Hermitian systems exotic\nnodal manifolds can be bounded by exceptional points in the bulk band\nstructure. Such exceptional points, at which energy bands coalesce with band\nconservation violated, are iconic for non-Hermitian systems. In this work, we\nshow that a variety of nodal lines and drumheads with exceptional boundary can\nbe realized on 2D and 3D honeycomb lattices through natural and physically\nfeasible non-Hermitian processes. The bulk nodal Fermi-arc and drumhead states,\nalthough is analogous to, but should be essentially distinguished from the\nsurface counterpart of Weyl and nodal-line semimetals, respectively, for which\nsurface nodal-manifold bands eventually sink into bulk bands. Then we\nrigorously examine the bulk-boundary correspondence of these exotic states with\nopen boundary condition, and find that these exotic bulk states are thereby\nundermined, showing the essential importance of periodic boundary condition for\nthe existence of these exotic states. As periodic boundary condition is\nnon-realistic for real materials, we furthermore propose a practically feasible\nelectrical-circuit simulation, with non-Hermitian devices implemented by\nordinary operational amplifiers, to emulate these extraordinary states."
    },
    {
        "anchor": "Moir\u00e9 ordered current loops in the graphene twist bilayer: While a typical material exhibits field induced currents only at the\nboundary, a uniform out-of-plane magnetic field applied to two mutually rotated\nlayers of graphene is shown to result in an ordered array of permanent current\nloops throughout the material. Each current loop consists of an interlayer\ncurrent flowing through the open AA stacked regions of the moir\\'e created by\nrotation, which then flows back through the neighboring AB regions to form a\ncircuit, with significant current strength even at small fields. Similar\nmoir\\'e ordered arrays of current loops are also shown to exist in\nnon-equilibrium transport states, where they manifest as current back flowing\nagainst the applied bias in the device. Such current loops thus represent an\nintrinsic feature of the twist bilayer in conditions of broken time reversal\nsymmetry, and exist both as a low field imprint of the moir\\'e lattice on\nLandau physics, and as measurable moir\\'e scale current configurations in\ntransport states.",
        "positive": "Edge and bulk effects in the Terahertz-photoconductivity of an antidot\n  superlattice: We investigate the Terahertz(THz)-response of a square antidot superlattice\nby means of photoconductivity measurements using a\nFourier-transform-spectrometer. We detect, spectrally resolved, the cyclotron\nresonance and the fundamental magnetoplasmon mode of the periodic superlattice.\nIn the dissipative transport regime both resonances are observed in the\nphotoresponse. In the adiabatic transport regime, at integer filling factor\n$\\nu =2$, only the cyclotron resonance is observed. From this we infer that\ndifferent mechanisms contribute to converting the absorption of THz-radiation\ninto photoconductivity in the cyclotron and in the magnetoplasmon resonances,\nrespectively."
    },
    {
        "anchor": "Topological nodal line semimetals with chiral symmetry: Topological semimetals in three dimensions display band-touchings at points\n(Weyl or Dirac semimetals) or nodal lines in the Brillouin zone. Weyl\nsemimetals can occur with internal symmetries only (time-reversal ${\\cal T}$,\ncharge conjugation ${\\cal C}$, and a product of the two, called\nchiral/sublattice symmetry ${\\cal S}={\\cal T}{\\cal C}$). Nodal line semimetals\npossessing solely internal symmetries have only been classified abstractly,\nwhile those with SU(2) spin rotation or crystalline symmetries are known more\nexplicitly. We show that chiral symmetry classes that are topologically\nnontrivial in three dimensions (namely class AIII, CII, CI, and DIII) always\nhave a stable gapless phase, which is a topological nodal line semimetal. Our\nclassification differs from previous approaches and has direct implications for\ngapless surface states.",
        "positive": "Dielectric sensing by charging energy modulation in a nano-granular\n  metal: Several sensing concepts using nanostructures prepared by focused electron\nbeam induced deposition have been developed over the last years. Following work\non highly miniaturized Hall sensors for magnetic sensing with soft magnetic Co,\nstrain and force sensing based on nano-granular platinum-carbon structures\n(Pt(C)) was introduced. Very recently the capability of nano-granular Pt(C)\nstructures to detect the presence of adsorbate water layers by conductance\nmodulations was demonstrated. For magnetic and strain sensing the underlying\nphysical mechanisms of the sensing effect have been analyzed in detail and are\nnow quite well understood. This is not the case for the adsorbate layer induced\nconductance modulation effect. Here we provide a theoretical framework that\nallows for a semi-quantitative understanding of the observed water-sensing\neffect. We show how the near-interface renormalization of the Coulomb charging\nenergy in the nano-granular metal caused by the dielectric screening of the\npolarizable adsorbate layer leads to a conductance modulation. The model can\naccount for the conductance modulation observed in the water adsorbate\nexperiments and can also be applied to understand similar effects caused by\nnear-interface dielectric anomalies of ferroelectric thin films on top of\nnano-granular Pt(C). Our findings provide a pathway towards optimized\nnano-granular layer structures suitable for a wide range of dielectric or local\npotential sensing applications."
    },
    {
        "anchor": "Parity Effects in Eigenvalue Correlators, Parametric and Crossover\n  Correlators in Random Matrix Models: Application to Mesoscopic systems: This paper summarizes some work I've been doing on eigenvalue correlators of\nRandom Matrix Models which show some interesting behaviour. First we consider\nmatrix models with gaps in there spectrum or density of eigenvalues. The\ndensity-density correlators of these models depend on whether N, where N is the\nsize of the matrix, takes even or odd values. The fact that this dependence\npersists in the large N thermodynamic limit is an unusual property and may have\nconsequences in the study of one electron effects in mesoscopic systems.\nSecondly, we study the parametric and cross correlators of the Harish\nChandra-Itzykson-Zuber matrix model. The analytic expressions determine how the\ncorrelators change as a parameter (e.g. the strength of a perturbation in the\nhamiltonian of the chaotic system or external magnetic field on a sample of\nmaterial) is varied. The results are relevant for the conductance fluctuations\nin disordered mesoscopic systems.",
        "positive": "Scanned Probe Microscopy of Electronic Transport in Carbon Nanotubes: We use electrostatic force microscopy and scanned gate microscopy to probe\nthe conducting properties of carbon nanotubes at room temperature. Multi-walled\ncarbon nanotubes are shown to be diffusive conductors, while metallic\nsingle-walled carbon nanotubes are ballistic conductors over micron lengths.\nSemiconducting single-walled carbon nanotubes are shown to have a series of\nlarge barriers to conduction along their length. These measurements are also\nused to probe the contact resistance and locate breaks in carbon nanotube\ncircuits."
    },
    {
        "anchor": "Aharonov-Bohm Effect in the Quantum Hall Regime and fingering\n  instability: The shape of an electronic droplet in the quantum Hall effect is sensitive to\ngradients of the magnetic field, even if they are placed outside the droplet.\nMagnetic impurities cause a fingering instability of the edge of the droplet,\nsimilar to the Saffman-Taylor fingering instability of an interface between two\nimmiscible phases. We discuss the fingering instability and some algebraic\naspects of the electronic states in a strong nonuniform field.",
        "positive": "Plasmon and dielectric background inhomogeneity enhancement of Coulomb\n  drag in graphene double-layer structures: The drag of massless fermions in graphene double-layer structures is\ninvestigated in a wide rage of temperatures and inter-layer separations. We\nshow that the inhomogeneity of the dielectric background in such graphene\nstructures for experimentally relevant parameters results in a significant\nenhancement of the drag resistivity. At intermediate temperatures the dynamical\nscreening via plasmon-mediated drag enhances the drag resistivity and results\nin an upturn in its behavior at large inter-layer separations. In a range of\ninter-layer separations, corresponding to the strong-to-weak crossover coupling\nof graphene layers, we find that the drag resistivity decreases approximately\nquadratically with the inter-layer spacing. This dependence weakens with a\ndecrease of the inter-layer spacing while for larger separations we recover the\ncubic (quartic) dependence at intermediate (low) temperatures."
    },
    {
        "anchor": "Proximity-induced superconducting gap in the quantum spin Hall edge\n  state of monolayer WTe$_2$: The quantum spin Hall (QSH) state was recently demonstrated in monolayers of\nthe transition metal dichalcogenide 1T'-WTe$_2$ and is characterized by a band\ngap in the two-dimensional (2D) interior and helical one-dimensional (1D) edge\nstates. Inducing superconductivity in the helical edge states would result in a\n1D topological superconductor, a highly sought-after state of matter. In the\npresent study, we use a novel dry-transfer flip technique to place\natomically-thin layers of WTe$_2$ on a van der Waals superconductor, NbSe$_2$.\nUsing scanning tunneling microscopy and spectroscopy (STM/STS), we demonstrate\natomically clean surfaces and interfaces and the presence of a\nproximity-induced superconducting gap in the WTe$_2$ for thicknesses from a\nmonolayer up to 7 crystalline layers. At the edge of the WTe$_2$ monolayer, we\nshow that the superconducting gap coexists with the characteristic\nspectroscopic signature of the QSH edge state. Taken together, these\nobservations provide conclusive evidence for proximity-induced\nsuperconductivity in the QSH edge state in WTe$_2$, a crucial step towards\nrealizing 1D topological superconductivity and Majorana bound states in this\nvan der Waals material platform.",
        "positive": "Giant Voltage Manipulation of MgO-based Magnetic Tunnel Junctions via\n  Localized Anisotropic Strain: a Potential Pathway to Ultra-Energy-Efficient\n  Memory Technology: Strain-mediated voltage control of magnetization in\npiezoelectric/ferromagnetic systems is a promising mechanism to implement\nenergy-efficient spintronic memory devices. Here, we demonstrate giant voltage\nmanipulation of MgO magnetic tunnel junctions (MTJ) on a\nPb(Mg1/3Nb2/3)0.7Ti0.3O3 (PMN-PT) piezoelectric substrate with (001)\norientation. It is found that the magnetic easy axis, switching field, and the\ntunnel magnetoresistance (TMR) of the MTJ can be efficiently controlled by\nstrain from the underlying piezoelectric layer upon the application of a gate\nvoltage. Repeatable voltage controlled MTJ toggling between high/low-resistance\nstates is demonstrated. More importantly, instead of relying on the intrinsic\nanisotropy of the piezoelectric substrate to generate the required strain, we\nutilize anisotropic strain produced using local gating scheme, which is\nscalable and amenable to practical memory applications. Additionally, the\nadoption of crystalline MgO-based MTJ on piezoelectric layer lends itself to\nhigh TMR in the strain-mediated MRAM devices."
    },
    {
        "anchor": "Full Counting Statistics of Quantum Point Contact with Time-dependent\n  Transparency: We analyse the zero temperature Full Counting Statistics (FCS) for the charge\ntransfer across a biased tunnel junction. We find the FCS from the eigenvalues\nof the density matrix of outgoing states of one lead. In the general case of a\ngeneral time-dependent bias and time-dependent transparency we solve for these\neigenvalues numerically. We report the FCS for the case of a step pulse applied\nbetween the leads and a constant barrier transparency (this case is equivalent\nto Fermi edge singularity problem). We have also studied combinations of a\ntime-dependent barrier transparency and biases between the leads. In particular\nwe look at protocols which excite the minimal number of excitations for a given\ncharge transfer (low noise electron source) and protocols which maximise\nentanglement of charge states.",
        "positive": "Photoinduced topological phase transition from a crossing-line nodal\n  semimetal to a multiple-Weyl semimetal: We propose a simple scheme to construct a model whose Fermi surface is\ncomprised of crossing-line nodes. The Hamiltonian consists of a normal hopping\nterm and an additional term which is odd under the mirror reflection. The line\nnodes appear along the mirror-invariant planes, where each line node carries\nthe quantized Berry magnetic flux. We explicitly construct a model with the\n$N$-fold rotational symmetry, where the $2N$ line nodes merge at the north and\nsouth poles. Photoirradiation induces a topological phase transition. When we\napply photoirradiation along the $k_z$ axis, there emerge point nodes carrying\nthe monopole charge $\\pm N$ at these poles, while all the line nodes disappear.\nThe resultant system describes anisotropic multiple-Weyl fermions."
    },
    {
        "anchor": "Complete light absorption in graphene-metamaterial corrugated structures: We show that surface-plasmon polaritons excited in negative permittivity\nmetamaterials having shallow periodic surface corrugation profiles can be\nexplored to push the absorption of single and continuous sheets of graphene up\nto 100%. In the relaxation regime, the position of the plasmonic resonances of\nthe hybrid system is determined by the plasma frequency of the metamaterial,\nallowing the frequency range for enhanced absorption to be set without the need\nof engineering graphene.",
        "positive": "Observation of High Harmonics of the Cyclotron Resonance in Microwave\n  Transmission of a High-Mobility Two-Dimensional Electron System: We report an observation of magnetooscillations of the microwave power\ntransmitted through the high mobility two-dimensional electron system hosted by\na GaAs quantum well. The oscillations reflect an enhanced absorption of\nradiation at high harmonics of the cyclotron resonance and follow\nsimultaneously measured microwave-induced resistance oscillations (MIRO) in the\ndc transport. While the relative amplitude (up to 1%) of the transmittance\noscillations appears to be small, they represent a significant (>50%)\nmodulation of the absorption coefficient. The analysis of obtained results\ndemonstrates that the low-B decay, magnitude, and polarization dependence of\nthe transmittance oscillations accurately follow the theory describing\nphoton-assisted scattering between distant disorder-broadened Landau levels.\nThe extracted sample parameters reasonably well describe the concurrently\nmeasured MIRO. Our results provide an insight into the MIRO polarization\nimmunity problem and pave the way to probe diverse high-frequency transport\nproperties of high-mobility systems using precise transmission measurements."
    },
    {
        "anchor": "Internal transitions of quasi-2D charged magneto-excitons in the\n  presence of purposely introduced weak lateral potential energy variations: Optically detected resonance spectroscopy has been used to investigate\neffects of weak random lateral potential energy fluctuations on internal\ntransitions of charged magneto-excitons (trions) in quasi two-dimensional\nGaAs/AlGaAs quantum-well (QW) structures. Resonant changes in the ensemble\nphotoluminescence induced by far-infrared radiation were studied as a function\nof magnetic field for samples having: 1) no growth interrupts (short range\nwell-width fluctuations), and 2) intentional growth interrupts (long range\nmonolayer well-width differences). Only bound-to-continuum internal transitions\nof the negatively charged trion are observed for samples of type 1. In\ncontrast, a feature on the high field (low energy) side of electron cyclotron\nresonance is seen for samples of type 2 with well widths of 14.1 and 8.4 nm.\nThis feature is attributed to a bound-to-bound transition of the spin-triplet\nwith non-zero oscillator strength resulting from breaking of translational\nsymmetry.",
        "positive": "Chiral topological phases in designed mechanical networks: Mass-spring networks (MSNs) have long been used as approximate descriptions\nof many biological and engineered systems, from actomyosin networks to\nmechanical trusses. In the last decade, MSNs have re-attracted theoretical\ninterest as models for phononic metamaterials with exotic properties such as\nnegative Poisson's ratio, negative effective mass, or gapped vibrational\nspectra. A practical advantage of MSNs is their tuneability, which allows the\ninverse design of materials with pre-specified bandgaps. Building on this fact,\nwe demonstrate here that designed MSNs, when subjected to Coriolis forces, can\nhost topologically protected chiral edge modes at predetermined frequencies,\nthus enabling robust unidirectional transmission of mechanical waves. Similar\nto other recently discovered topological materials, the topological phases of\nMSNs can be classified by a Chern invariant related to time-reversal symmetry\nbreaking."
    },
    {
        "anchor": "Angular dependence of magnetoresistance and Fermi-surface shape in\n  quasi-2D metals: The analytical and numerical study of the angular dependence of\nmagnetoresistance in layered quasi-two-dimensional (Q2D) metals is performed.\nThe harmonic expansion analytical formulas for the angular dependence of\nFermi-surface cross-section area in external magnetic field are obtained for\nvarious typical crystal symmetries. The simple azimuth-angle dependence of the\nYamaji angles is derived for the elliptic in-plane Fermi surface. These\nformulas correct some previous results and allow the simple and effective\ninterpretation of the magnetic quantum oscillations data in cuprate\nhigh-temperature superconducting materials, in organic metals and other Q2D\nmetals. The relation between the angular dependence of magnetoresistance and of\nFermi-surface cross-section area is derived. The applicability region of all\nresults obtained and of some previous widely used analytical results is\ninvestigated using the numerical calculations.",
        "positive": "Analytical solutions of topological surface states in a series of\n  lattice models: We derive the analytical solutions of surface states in a series of lattice\nmodels for three-dimensional topological insulators and their nontopological\ncounterparts based on an ansatz. A restriction on the spin-flip matrices in\nnearest-neighbor hopping characterizes the series. This restriction affords the\nansatz and favors analytical solvability of surface-state eigenvectors. Despite\nthe restriction, the series retains sufficient designability to describe\nvarious types of surface states. We also describe how it can serve as a\ntractable tool for elucidating unique phenomena on topological surfaces."
    },
    {
        "anchor": "Machine Learning Diffusion Monte Carlo Energies: We present two machine learning methodologies that are capable of predicting\ndiffusion Monte Carlo (DMC) energies with small datasets (~60 DMC calculations\nin total). The first uses voxel deep neural networks (VDNNs) to predict DMC\nenergy densities using Kohn-Sham density functional theory (DFT) electron\ndensities as input. The second uses kernel ridge regression (KRR) to predict\natomic contributions to the DMC total energy using atomic environment vectors\nas input (we used atom centred symmetry functions, atomic environment vectors\nfrom the ANI models, and smooth overlap of atomic positions). We first compare\nthe methodologies on pristine graphene lattices, where we find the KRR\nmethodology performs best in comparison to gradient boosted decision trees,\nrandom forest, gaussian process regression, and multilayer perceptrons. In\naddition, KRR outperforms VDNNs by an order of magnitude. Afterwards, we study\nthe generalizability of KRR to predict the energy barrier associated with a\nStone-Wales defect. Lastly, we move from 2D to 3D materials and use KRR to\npredict total energies of liquid water. In all cases, we find that the KRR\nmodels are more accurate than Kohn-Sham DFT and all mean absolute errors are\nless than chemical accuracy.",
        "positive": "Mechanisms of the microwave photoconductivity in 2D electron systems\n  with mixed disorder: We present a systematic study of the microwave-induced oscillations in the\nmagnetoresistance of a 2D electron gas for mixed disorder including both\nshort-range and long-range components. The obtained photoconductivity tensor\ncontains contributions of four distinct transport mechanisms. We show that the\nphotoresponse depends crucially on the relative weight of the short-range\ncomponent of disorder. Depending on the properties of disorder, the theory\nallows one to identify the temperature range within which the photoresponse is\ndominated by one of the mechanisms analyzed in the paper."
    },
    {
        "anchor": "Co-tunneling assisted sequential tunneling in multi-level quantum dots: We investigate the conductance and zero-frequency shot noise of interacting,\nmulti-level quantum dots coupled to leads. We observe that co-tunneling\nassisted sequential tunneling (CAST) processes play a dominant role in the\ntransition region from Coulomb blockade to sequential tunneling. We analyze for\nintermediate coupling strength the dependence of the conductance due to CAST\nprocesses on temperature, coupling constant, and gate voltage. Remarkably, the\nwidth of the CAST transport feature scales only with temperature, but not with\nthe coupling constant. While the onset of inelastic co-tunneling is associated\nwith a super-Poissonian noise, the noise is even stronger above the threshold\nfor CAST processes",
        "positive": "Electronic statistics-on-demand: bunching, anti-bunching, positive and\n  negative correlations in a molecular spin-valve: One of the long-standing goals of quantum transport is to use the noise,\nrather than the average current, for information processing. However, achieving\nthis requires on-demand control of quantum fluctuations in the electric\ncurrent. In this paper, we demonstrate theoretically that transport through a\nmolecular spin-valve provides access to many different statistics of electron\ntunneling events. Simply by changing highly tunable parameters, such as\nelectrode spin-polarization, magnetization angle, and voltage, one is able to\nswitch between Poisson behavior, bunching and anti-bunching of electron\ntunnelings, and positive and negative temporal correlations. The molecular\nspin-valve is modeled by a single spin-degenerate molecular orbital with local\nelectronic repulsion coupled to two ferromagnetic leads with magnetization\norientations allowed to rotate relative to each other. The electron transport\nis described via Born-Markov master equation and fluctuations are studied with\nhigher-order waiting time distributions. For highly magnetized parallel-aligned\nelectrodes, we find that strong positive temporal correlations emerge in the\nvoltage range where the second transport channel is partially open. These are\ncaused by a spin-induced electron-bunching, which does not manifest in the\nstationary current alone."
    },
    {
        "anchor": "Dimensionality-dependent type-II Weyl semimetal state in\n  Mo$_{0.25}$W$_{0.75}$Te$_{2}$: Weyl nodes and Fermi arcs in type-II Weyl semimetals (WSMs) have led to lots\nof exotic transport phenomena. Recently, Mo$_{0.25}$W$_{0.75}$Te$_{2}$ has been\nestablished as a type-II WSM with Weyl points located near Fermi level, which\noffers an opportunity to study its intriguing band structure by electrical\ntransport measurements. Here, by selecting a special sample with the thickness\ngradient across two- (2D) and three-dimensional (3D) regime, we show strong\nevidences that Mo$_{0.25}$W$_{0.75}$Te$_{2}$ is a type-II Weyl semimetal by\nobserving the following two dimensionality-dependent transport features: 1) A\nchiral-anomaly-induced anisotropic magneto-conductivity enhancement,\nproportional to the square of in-plane magnetic field (B$_{in}$$^{2}$); 2) An\nadditional quantum oscillation with thickness-dependent phase shift. Our\ntheoretical calculations show that the observed quantum oscillation originates\nfrom a Weyl-orbit-like scenario due to the unique band structure of\nMo$_{0.25}$W$_{0.75}$Te$_{2}$. The in situ dimensionality-tuned transport\nexperiment offers a new strategy to search for type-II WSMs.",
        "positive": "Vibrational nonequilibrium effects in the conductance of\n  single-molecules with multiple electronic states: Vibrational nonequilibrium effects in charge transport through\nsingle-molecule junctions are investigated. Focusing on molecular bridges with\nmultiple electronic states, it is shown that electronic-vibrational coupling\ntriggers a variety of vibronic emission and absorption processes, which\ninfluence the conductance properties and mechanical stability of\nsingle-molecule junctions profoundly. Employing a master equation and a\nnonequilibrium Green's function approach, these processes are analyzed in\ndetail for a generic model of a molecular junction and for\nbenzenedibutanethiolate bound to gold electrodes."
    },
    {
        "anchor": "Switching the magnetization of magnetostrictive nanomagnets from\n  single-domain to non-volatile vortex states with a surface acoustic wave: We report manipulation of the magnetic states of elliptical cobalt\nmagnetostrictive nanomagnets (of nominal dimensions ~ 340 nm x 270 nm x 12 nm)\ndelineated on bulk 128{\\deg} Y-cut lithium niobate with Surface Acoustic Waves\n(SAWs) launched from interdigitated electrodes. Isolated nanomagnets that are\ninitially magnetized to a single domain state with magnetization pointing along\nthe major axis of the ellipse are driven into a vortex state by surface\nacoustic waves that modulate the stress anisotropy of these nanomagnets. The\nnanomagnets remain in the vortex state until they are reset by a strong\nmagnetic field to the initial single domain state, making the vortex state\nnon-volatile. This phenomenon is modeled and explained using a micromagnetic\nframework and could lead to the development of extremely energy efficient\nmagnetization switching methodologies.",
        "positive": "Fabry-P\u00e9rot interference in a triple-gated quantum point contact: We demonstrated that a triple-gated GaAs quantum point contact, which has an\nadditional surface gate between a pair of split gates to strengthen the lateral\nconfinement, produces the well-defined quantized conductance and\nFabry-P\\'erot-type (FP-type) oscillations on it even using a relatively low\nmobility wafer. A one-dimensional phenomenological model potential was\ndeveloped to explain the oscillatory behavior. By combining the model\ncalculations and dc bias spectroscopy, we obtained detailed information about\nthe energy scales of the oscillatory structures. The relationships between the\nFP-type oscillations and the anomaly below the first plateau will be addressed."
    },
    {
        "anchor": "A study of electron and thermal transport in layered Titanium disulphide\n  single crystals: We present a detailed study of thermal and electrical transport behavior of\nsingle crystal Titanium disulphide flakes, which belongs to the two\ndimensional, transition metal dichalcogenide class of materials. In-plane\nSeebeck effect measurements revealed a typical metal-like linear temperature\ndependence in the range of 85 - 285 K. Electrical transport measurements with\nin-plane current geometry exhibited a nearly T^2 dependence of resistivity in\nthe range of 10 - 300 K. However, transport measurements along the out-of-plane\ncurrent geometry showed a transition in temperature dependence of resistivity\nfrom T^2 to T^5 beyond 200 K. Interestingly, Au ion-irradiated TiS2 samples\nshowed a similar T 5 dependence of resistivity beyond 200 K, even in the\ncurrent-in-plane geometry. Micro- Raman measurements were performed to study\nthe phonon modes in both pristine and ion-irradiated TiS2 crystals.",
        "positive": "Transmission and conductance across junctions of isotropic and\n  anisotropic three-dimensional semimetals: We compute the transmission coefficients and zero-temperature conductance for\nchiral quasiparticles propagating through various geometries, which consist of\njunctions of three-dimensional nodal-point semimetals. In the first scenario,\nwe consider a potential step with two Rarita-Schwinger-Weyl or two birefringent\nsemimetals, which are tilted with respect to the other on the two sides of the\njunction. The second set-up consists of a junction between a doped Dirac\nsemimetal and a ferromagnetic Weyl semimetal, where an intrinsic magnetization\npresent in the latter splits the doubly-degenerate Dirac node into a pair of\nWeyl nodes. A scalar potential is also applied in the region where the Weyl\nsemimetal phase exists. Finally, we study sandwiches of Weyl/multi-Weyl\nsemimetals, with the middle region being subjected to both scalar and vector\npotentials. Our results show that a nonzero transmission spectrum exists where\nthe areas, enclosed by the Fermi surface projections (in the plane\nperpendicular to the propagation axis) of the incidence and transmission\nregions, overlap. Such features can help engineer unidirectional carrier\npropagation, topologically protected against impurity backscattering, because\nof the chiral nature of the charge carriers."
    },
    {
        "anchor": "Molecular electronics in junctions with energy disorder: We investigate transport through molecular wires whose energy levels are\naffected by environmental fluctuations. We assume that the relevant\nfluctuations are so slow that they, within a tight-binding description, can be\ndescribed by disordered, Gaussian distributed onsite energies. For long wires,\nwe find that the corresponding current distribution can be rather broad even\nfor a small energy variance. Moreover, we analyse with a Floquet master\nequation the interplay of laser excitations and static disorder. Then the\ndisorder leads to spatial asymmetries such that the laser diving can induce a\nratchet current.",
        "positive": "Electronic control of the spin-wave damping in a magnetic insulator: It is demonstrated that the decay time of spin-wave modes existing in a\nmagnetic insulator can be reduced or enhanced by injecting an in-plane dc\ncurrent, $I_\\text{dc}$, in an adjacent normal metal with strong spin-orbit\ninteraction. The demonstration rests upon the measurement of the ferromagnetic\nresonance linewidth as a function of $I_\\text{dc}$ in a 5~$\\mu$m diameter\nYIG(20nm){\\textbar}Pt(7nm) disk using a magnetic resonance force microscope\n(MRFM). Complete compensation of the damping of the fundamental mode is\nobtained for a current density of $\\sim 3 \\cdot 10^{11}\\text{A.m}^{-2}$, in\nagreement with theoretical predictions. At this critical threshold the MRFM\ndetects a small change of static magnetization, a behavior consistent with the\nonset of an auto-oscillation regime."
    },
    {
        "anchor": "Generating two continuous entangled microwave beams using a dc-biased\n  Josephson junction: We show experimentally that a dc-biased Josephson junction in series with two\nmicrowave resonators emits entangled beams of microwaves leaking out of the\nresonators. In the absence of a stationary phase reference for characterizing\nthe entanglement of the outgoing beams, we measure second-order coherence\nfunctions for proving entanglement up to an emission rate of 2.5 billion photon\npairs per second. The experimental results are found in quantitative agreement\nwith theory, proving that the low frequency noise of the dc bias is the main\nlimitation for the coherence time of the entangled beams. This agreement allows\nus to evaluate the entropy of entanglement of the resonators, and to identify\nthe improvements that could bring this device closer to a useful bright source\nof entangled microwaves for quantum-technological applications.",
        "positive": "Tunneling through two resonant levels: fixed points and conductances: We study point contact tunneling between two leads of a Tomonaga-Luttinger\nliquid through two degenerate resonant levels in parallel. This is one of the\nsimplest cases of a quantum junction problem where the Fermi statistics of the\nelectrons plays a non-trivial role through the Klein factors appearing in\nbosonization. Using a mapping to a `generalized Coulomb model' studied in the\ncontext of the dissipative Hofstadter model, we find that any asymmetry in the\ntunneling amplitudes from the two leads grows at low temperatures, so that\nultimately there is no conductance across the system. For the symmetric case,\nwe identify a non-trivial fixed point of this model; the conductance at that\npoint is generally different from the conductance through a single resonant\nlevel."
    },
    {
        "anchor": "Quantum Ring in Gapped Graphene Layer with Wedge Disclination in the\n  Presence of an Uniform Magnetic Field: In this paper we investigate the relativistic quantum dynamics of a massive\nexcitation in a graphene layer with a wedge disclination in the presence of an\nuniform magnetic field. We use a Dirac oscillator type coupling to introduce\nthe confining potential for massive fermions in this system. We obtain the\nenergy spectrum and eigenfunctions for the quantum ring pierced by\nAharonov-Bohm flux resulting in appearance of persistent current and\nspontaneous magnetization.",
        "positive": "Radio-frequency point-contact electrometer: We fabricate and characterize a radio-frequency semiconductor point-contact\nelectrometer (RF-PC) analogous to radio-frequency single-electron transistors\n[RF-SETs, see Science {\\bf 280}, 1238 (1998)]. The point contact is formed by\nsurface Schottky gates in a two-dimensional electron gas (2DEG) in an\nAlGaAs/GaAs heterostructure. In the present setup, the PC is operating as a\nsimple voltage-controlled resistor rather than a quantum point contact (QPC)\nand demonstrates a charge-sensitivity about $2\\times 10^{-1}\n\\mathrm{e/\\sqrt{Hz}}$ at a bandwidth of $30 \\mathrm{kHz}$ without the use of a\ncryogenic RF preamplifier. Since the impedance of a typical point-contact\ndevice is much lower than the impedance of the typical SET, a\nsemiconductor-based RF-PC, equipped with practical cryogenic RF preamplifiers,\ncould realize an ultra-fast and ultra-sensitive electrometer."
    },
    {
        "anchor": "Correlation induced resonances in transport through coupled quantum dots: We investigate the effect of local electron correlations on transport through\nparallel quantum dots. The linear conductance as a function of gate voltage is\nstrongly affected by the interplay of the interaction U and quantum\ninterference. We find a pair of novel correlation induced resonances separated\nby an energy scale that depends exponentially on U. The effect is robust\nagainst a small detuning of the dot energy levels and occurs for arbitrary\ngeneric tunnel couplings. It should be observable in experiments on the basis\nof presently existing double-dot setups.",
        "positive": "Demonstration of electron focusing using electronic lenses in\n  low-dimensional system: We report an all-electric integrable electron focusing lens in n-type GaAs.\nIt is shown that a pronounced focusing peak takes place when the focal point\naligns with an on-chip detector. The intensity and full width half maximum\n(FWHM) of the focusing peak are associated with the collimation of injected\nelectrons. To demonstrate the reported focusing lens can be a useful tool, we\ninvestigate characteristic of an asymmetrically gate biased quantum point\ncontact with the assistance of focusing lens. A correlation between the\noccurrence of conductance anomaly in low conductance regime and increase in\nFWHM of focusing peak is observed. The correlation is likely due to the\nelectron-electron interaction. The reported electron focusing lens is essential\nfor a more advanced electron optics device."
    },
    {
        "anchor": "Observation of anisotropic interlayer Raman modes in few-layer ReS2: ReS$_2$ has recently emerged as a new member in the rapidly growing family of\ntwo-dimensional materials. Unlike MoS$_2$ or WSe$_2$, the optical and\nelectrical properties of ReS$_2$ are not isotropic due to the reduced symmetry\nof the crystal. Here, we present layer-dependent Raman measurements of ReS$_2$\nsamples ranging from monolayers to ten layers in the ultralow frequency regime.\nWe observe layer breathing and shear modes which allow for easy assignment of\nthe number of layers. Polarization-dependent measurements give further insight\ninto the crystal structure and reveal an energetic shift of the shear mode\nwhich stems from the in-plane anisotropy of the shear modulus in this material.",
        "positive": "Route towards Localization for Quantum Anomalous Hall Systems with Chern\n  Number 2: The quantum anomalous Hall system with Chern number 2 can be destroyed by\nsufficiently strong disorder. During its process towards localization, it was\nfound that the electronic states will be directly localized to an Anderson\ninsulator (with Chern number 0), without an intermediate Hall plateau with\nChern number 1. Here we investigate the topological origin of this phenomenon,\nby calculating the band structures and Chern numbers for disordered supercells.\nWe find that on the route towards localization, there exists a hidden state\nwith Chern number 1, but it is too short and too fluctuating to be practically\nobservable. This intermediate state cannot be stabilized even after some \"smart\ndesign\" of the model and this should be a universal phenomena for insulators\nwith high Chern numbers. By performing numerical scaling of conductances, we\nalso plot the renormalization group flows for this transition, with Chern\nnumber 1 state as an unstable fixed point. This is distinct from known results,\nand can be tested by experiments and further theoretical analysis."
    },
    {
        "anchor": "Magnetic moments in a helical edge can make weak correlations seem\n  strong: We study the effect of localized magnetic moments on the conductance of a\nhelical edge. Interaction with a local moment is an effective backscattering\nmechanism for the edge electrons. We evaluate the resulting differential\nconductance as a function of temperature $T$ and applied bias $V$ for any value\nof $V/T$. Backscattering off magnetic moments, combined with the weak repulsion\nbetween the edge electrons results in a power-law temperature and voltage\ndependence of the conductance; the corresponding small positive exponent is\nindicative of insulating behavior. Local moments may naturally appear due to\ncharge disorder in a narrow-gap semiconductor. Our results provide an\nalternative interpretation of the recent experiment by Li et al. \\cite{Li15}\nwhere a power-law suppression of the conductance was attributed to strong\nelectron repulsion within the edge, with the value of Luttinger liquid\nparameter $K$ fine-tuned close to $1/4$.",
        "positive": "Plasmons in the presence of Tamm-Shockley states with Rashba splitting\n  at noble metal surfaces: Au(111) or similar noble metal surfaces feature Tamm-Shockley surface states\nthat are known to possess considerable spin-orbit splitting of the Rashba type\nof order $\\Delta=0.1$ eV. When interacting with an electromagnetic field such\nstates are expected to have resonances when the frequency of the field is near\nthe energy of the spin-orbit splitting $\\Delta$. These resonances originate in\nthe intersubband transitions between spin-split subbands. Such resonances can\nbe observed in the frequency dependence of the surface impedance. Plasmons in\nthin metal films are gapless and can be strongly affected by these spin\nresonances, acquiring significant modification of the spectrum when it\nintersects the $\\omega=\\Delta$ line. Finally, an interesting demonstration of\nthe intersubband resonances can be obtained when metal films are coated with\nionic dielectrics that have a frequency of longitudinal/transverse optical\nphonons above/below $\\Delta$. The dielectric function between the two optical\nphonon frequencies is negative which forbids propagation of conventional\nplasmon-polaritons. However, the presence of spin-orbit-split surface states\nallows plasmon-polaritons to exist in this otherwise forbidden range of\nfrequencies."
    },
    {
        "anchor": "Properties of low-lying states in some high-nuclearity Mn, Fe and V\n  clusters: Exact studies of Heisenberg models: Using an efficient numerical scheme that exploits spatial symmetries and spin\nparity, we have obtained the exact low-lying eigenstates of exchange\nHamiltonians for the high nuclearity spin clusters, Mn_{12}, Fe_8 and V_{15}.\nThe largest calculation involves the Mn_{12} cluster which spans a Fock space\nof a hundred million. Our results show that the earlier estimates of the\nexchange constants need to be revised for the Mn_{12} cluster to explain the\nlevel ordering of low-lying eigenstates. In the case of the Fe_8 cluster,\ncorrect level ordering can be obtained which is consistent with the exchange\nconstants for the already known clusters with butterfly structure. In the\nV_{15} cluster, we obtain an effective Hamiltonian that reproduces exactly, the\neight low-lying eigenvalues of the full Hamiltonian.",
        "positive": "Optimized Tersoff and Brenner empirical potential parameters for lattice\n  dynamics and phonon thermal transport in carbon nanotubes and graphene: We have examined the commonly used Tersoff and Brenner empirical interatomic\npotentials in the context of the phonon dispersions in graphene. We have found\na parameter set for each empirical potential that provides improved fits to\nsome structural data and to the in-plane phonon dispersion data for graphite.\nThese optimized parameter sets yield values of the acoustic phonon velocities\nthat are in better agreement with measured data. They also provide lattice\nthermal conductivity values in single-walled carbon nanotubes that are\nconsiderably improved compared to those obtained from the original parameter\nsets."
    },
    {
        "anchor": "Superconducting and excitonic quantum phase transitions in doped systems\n  with Dirac electrons: Material systems with Dirac electrons on a bipartite planar lattice and\npossessing superconducting and excitonic interactions are investigated both in\nthe half-filling and doped regimes at zero temperature. Excitonic pairing is\nthe analog of chiral symmetry breaking of relativistic fermion theories and\nproduces an insulating gap in the electronic spectrum. Condensed matter systems\nwith such competing interactions display phenomena that are analogous to the\nonset of the chiral condensate and of color superconductivity in dense quark\nmatter. Evaluation of the free-energy (effective potential) allows us to map\nthe phases of the system for different values of the couplings of each\ninteraction. At half-filling, we show that Cooper pairs and excitons can\ncoexist if the superconducting and excitonic interactions strengths are equal\nand above a quantum critical point, which is evaluated. If one of the\ninteractions is stronger than the other, then only the corresponding order\nparameter is non-vanishing and we do not have coexistence. For nonzero values\nof chemical potential, the phase diagram for each interaction is obtained\nindependently. Taking into account only the excitonic interaction, a critical\nchemical potential, as a function of the interaction strength, is obtained. If\nonly the superconducting interaction is considered, the superconducting gap\ndisplays a characteristic dome as charge carriers are doped into the system and\nour results qualitatively reproduce the superconducting phase diagram of\nseveral compounds, like 122 pnictides and cuprate superconductors. We also\nanalyze the possibility of coexistence between Cooper pairs and excitons and we\nshow that, even if the excitonic interaction strength is greater than the\nsuperconducting interaction, as the chemical potential increases,\nsuperconductivity tends to suppress the excitonic order parameter.",
        "positive": "Bloch-like oscillations induced by charge discreteness in quantum\n  mesoscopic rings: We study the effect of charge discreteness in a quantum mesoscopic ring wih\ninductance L. The ring is pierced by a time depending external magnetic field.\nWhen the external magnetic flux varies uniformly, the current induced in the\nring oscillates with a frequency proportional to the charge discreteness and\nthe flux variation. This phenomenon is very similar to the well known Bloch's\noscillation in crystals. The similitude is related to the charge discreteness\nin the charge-current representation, which plays the same role as the constant\nlattice in crystals."
    },
    {
        "anchor": "In Situ Resistance Measurements of Strained Carbon Nanotubes: We investigate the response of multi-walled carbon nanotubes to mechanical\nstrain applied with an Atomic Force Microscope (AFM) probe. We find that in\nsome samples, changes in the contact resistance dominate the measured\nresistance change. In others, strain large enough to fracture the tube can be\napplied without a significant change in the contact resistance. In this case we\nobserve that enough force is applied to break the tube without any change in\nresistance until the tube fails. We have also manipulated the ends of the\nbroken tube back in contact with each other, re-establishing a finite\nresistance. We observe that in this broken configuration the resistance of the\nsample is tunable to values 15-350 kW greater than prior to breaking.",
        "positive": "Skyrmion solids in monolayer graphene: Partially filled Landau levels host competing orders, with electron solids\nprevailing close to integer fillings before giving way to fractional quantum\nHall liquids as the Landau level fills. Here, we report the observation of an\nelectron solid with noncolinear spin texture in monolayer graphene, consistent\nwith solidification of skyrmions---topological spin textures characterized by\nquantized electrical charge. In electrical transport, electron solids reveal\nthemselves through a rapid metal-insulator transition in the bulk electrical\nconductivity as the temperature is lowered, accompanied by the emergence of\nstrongly nonlinear dependence on the applied bias voltage. We probe the spin\ntexture of the solids using a modified Corbino geometry that allows\nferromagnetic magnons to be launched and detected. We find that magnon\ntransport is highly efficient when one Landau level is filled ($\\nu=1$),\nconsistent with quantum Hall ferromagnetic spin polarization; however, even\nminimal doping immediately quenches the the magnon signal while leaving the\nvanishing low-temperature charge conductivity unchanged. Our results can be\nunderstood by the formation of a solid of charged skyrmions near $\\nu=1$, whose\nnoncolinear spin texture leads to rapid magnon decay. Data near fractional\nfillings further shows evidence for several fractional skyrmion crystals,\nsuggesting that graphene hosts a vast and highly tunable landscape of coupled\nspin and charge orders."
    },
    {
        "anchor": "Positive cross-correlations induced by ferromagnetic contacts: Due to the Fermionic nature of carriers, correlations between electric\ncurrents flowing through two different contacts attached to a conductor present\na negative sign. Possibility for positive cross-correlations has been\ndemonstrated in hybrid normal/superconductor structures under certain\nconditions. In this paper we show that positive cross-correlations can be\ninduced, if not already present, in such structures by employing ferromagnetic\nleads with magnetizations aligned anti-parallel to each other. We consider\nthree-terminal hybrid structures and calculate the mean-square correlations of\ncurrent fluctuations as a function of the bias voltage at finite temperature.",
        "positive": "Thermodynamic Properties of electrically modulated monolayer Graphene: Theoretical investigation of thermodynamic properties of electrically\nmodulated monolayer graphene in the presence of a perpendicular magnetic field\nB is presented.This work is aimed at determining the modulation induced effects\non the thermodynamic properties of electrically modulated graphene.The results\nobtained are compared with those of the conventional 2DEG. The one-dimensional\nperiodic potential due to electric modulation lifts the degeneracy of the\nLandau Levels and converts them into bands whose width oscillates as a function\nof B. We find Weiss type oscillations for small values of B and dHvA type\noscillations at larger values values of $B$. We find that the modulation\ninduced effects on the thermodynamic properties are enhanced and less damped\nwith temperature in graphene compared with conventional 2DEG system."
    },
    {
        "anchor": "Two and One-dimensional Honeycomb Structure of Boron Nitride: This paper presents a systematic study of two and one dimensional honeycomb\nstructure of boron nitride (BN) using first-principles plane wave method.\nTwo-dimensional (2D) graphene like BN is a wide band gap semiconductor with\nionic bonding. Phonon dispersion curves demonstrate the stability of 2D BN\nflakes. Quasi 1D armchair BN nanoribbon are nonmagnetic semiconductors with\nedge states. Upon passivation of B and N with hydrogen atoms these edge states\ndisappear and band gap increases. Bare zigzag BN nanoribbons are metallic, but\nbecome a ferromagnetic semiconductor when their both edges are passivated with\nhydrogen. However, their magnetic ground state, electronic band structure and\nband gap are found to be strongly dependent on whether B- or N-edge of the\nribbon is saturated with hydrogen. Vacancy defects in armchair and zigzag\nnanoribbons affects also magnetic state and electronic structure. In order to\nreveal dimensionality effects these properties are contrasted with those of\nvarious 3D BN crystals and 1D BN atomic chain.",
        "positive": "Operating Nanobeams in a Quantum Fluid: Microelectromechanical (MEMS) and nanoelectromechanical systems (NEMS) are\nideal candidates for exploring quantum fluids since they can be manufactured\nreproducibly, cover the frequency range from hundreds of kilohertz up to\ngigahertz and usually have very low power dissipation. Their small size offers\nthe possibility of probing the superfluid on scales comparable to, and below,\nthe coherence length. That said, there have been hitherto no successful\nmeasurements of NEMS resonators in the liquid phases of helium. Here we report\nthe operation of doubly-clamped aluminum nanobeams in superfluid $^4$He at\ntemperatures spanning the superfluid transition. The devices are shown to be\nvery sensitive detectors of the superfluid density and the normal fluid\ndamping. However, a further and very important outcome of this work is the\nknowledge that now we have demonstrated that these devices can be successfully\noperated in superfluid $^4$He, it is straightforward to apply them in\nsuperfluid $^3$He which can be routinely cooled to below 100\\,$\\mu$K. This\nbrings us into the regime where nanomechanical devices operating at a few MHz\nfrequencies may enter their mechanical quantum ground state."
    },
    {
        "anchor": "Probing e-e interactions in a periodic array of GaAs quantum wires: We present the results of non-linear tunnelling spectroscopy between an array\nof independent quantum wires and an adjacent two-dimensional electron gas\n(2DEG) in a double-quantum-well structure. The two layers are separately\ncontacted using a surface-gate scheme, and the wires are all very regular, with\ndimensions chosen carefully so that there is minimal modulation of the 2DEG by\nthe gates defining the wires. We have mapped the dispersion spectrum of the 1D\nwires down to the depletion of the last 1D subband by measuring the conductance\n\\emph{G} as a function of the in-plane magnetic field \\emph{B}, the interlayer\nbias $V_{\\rm dc}$ and the wire gate voltage. There is a strong suppression of\ntunnelling at zero bias, with temperature and dc-bias dependences consistent\nwith power laws, as expected for a Tomonaga-Luttinger Liquid caused by\nelectron-electron interactions in the wires. In addition, the current peaks fit\nthe free-electron model quite well, but with just one 1D subband there is extra\nstructure that may indicate interactions.",
        "positive": "Can ultraprecision polishing techniques improve the coherence times of\n  nitrogen-vacancy centers in diamond?: We investigate the correlation between surface roughness and corresponding\n$T_2$ times of nearsurface nitrogen-vacancy centers (~7 nm/ 5 keV implantation\nenergy) in diamond. For this purpose we compare five different polishing\ntechniques, including both purely mechanical as well as chemical mechanical\napproaches, two different substrate sources (Diam2tec and Element Six) and two\ndifferent surface terminations (O- and H-termination) during nitrogen-vacancy\nforming. All coherence times are measured and compared before and after an\noxygen surface treatment at 520 {\\deg}C. We find that the coherence times of\nshallow nitrogen-vacancy centers are surprisingly independent of surface\nroughness."
    },
    {
        "anchor": "Temperature Dependence of the Electrical Transport Properties of\n  Multilayer Graphene: Multilayer graphene (MLG) thin films are deposited on silicon oxide\nsubstrates by mechanical exfoliation (or 'scotch-tape method') from Kish\ngraphite. The thickness and number of layers are determined from both Atomic\nForce Microscopy (AFM) and Raman Spectroscopy. Electrical terminals are\ndeposited on MLGs in a four-probe configuration by electron-beam lithography,\ngold/titanium thermal evaporation, and lift-off. The electrical resistance is\nmeasured from room temperature down to 2 K. The electrical resistance of the\nMLGs shows an increase with decreasing temperature, and then decreases after\nreaching a maximum value. These results are compared with recent experimental\nand theoretical data from the literature.",
        "positive": "Vibration-Assisted and Vibration-Hampered Excitonic Quantum Transport: The interplay between exctions and vibrations is considered to be a key\nfactor in determining the exciton transfer properties in light-harvesting\nexciton transfer complexes. Here we study this interplay theoretically in a\nmodel for exciton transport, composed of two chromophores coupled to an exciton\nsource and sink in the presence of vibrations. We consider two cases, that show\nqualitatively distinct transport features. In the first, the vibrations are\nglobal and affect the two chromophores simultaneously. In the second case, the\nvibrations are localized on each chromophore. For global vibrations, the\ncurrent exhibits {\\sl anti-resonances} as a function of the chromophore energy\ndifference, which are due to exciton-polaron interference. For local\nvibrations, on the other hand, the currents shows tunneling {\\sl resonances} at\nmultiples of the vibration energy. Counter-intuitively, both effects increase\nwith increasing temperature. Our results demonstrate that an environment can\neither assist or hamper exciton transport, and are in accord with current\nunderstanding of energy transfer in natural exciton transfer complexes."
    },
    {
        "anchor": "Low Gilbert Damping Constant in Perpendicularly Magnetized W/CoFeB/MgO\n  Films with High Thermal Stability: Perpendicular magnetic materials with low damping constant and high thermal\nstability have great potential for realizing high-density, non-volatile, and\nlow-power consumption spintronic devices, which can sustain operation\nreliability for high processing temperatures. In this work, we study the\nGilbert damping constant ({\\alpha}) of perpendicularly magnetized W/CoFeB/MgO\nfilms with a high perpendicular magnetic anisotropy (PMA) and superb thermal\nstability. The {\\alpha} of these PMA films annealed at different temperatures\nis determined via an all-optical Time-Resolved Magneto-Optical Kerr Effect\nmethod. We find that {\\alpha} of these W/CoFeB/MgO PMA films decreases with\nincreasing annealing temperature, reaches a minimum of {\\alpha} = 0.016 at an\nannealing temperature of 350 {\\deg}C, and then increases to 0.024 after\npost-annealing at 400 {\\deg}C. The minimum {\\alpha} observed at 350 {\\deg}C is\nrationalized by two competing effects as the annealing temperature becomes\nhigher: the enhanced crystallization of CoFeB and dead-layer growth occurring\nat the two interfaces of the CoFeB layer. We further demonstrate that {\\alpha}\nof the 400 {\\deg}C-annealed W/CoFeB/MgO film is comparable to that of a\nreference Ta/CoFeB/MgO PMA film annealed at 300 {\\deg}C, justifying the\nenhanced thermal stability of the W-seeded CoFeB films.",
        "positive": "Non-Hermitian chiral anomalies in interacting systems: The emergence of chiral anomaly entails various fascinating phenomena such as\nanomalous quantum Hall effect and chiral magnetic effect in different branches\nof (non-)Hermitian physics. While in the single-particle picture, anomalous\ncurrents merely appear due to the coupling of massless particles with\nbackground fields, many-body interactions can also be responsible for anomalous\ntransport in interacting systems. In this Letter, we study anomalous chiral\ncurrents in systems where interacting massless fermions with complex Fermi\nvelocities are coupled to complex gauge fields. Our results reveal that\nincorporating non-Hermiticity and many-body interactions gives rise to\nadditional terms in anomalous relations beyond their Hermitian counterparts. We\nfurther present that many-body corrections in the subsequent non-Hermitian\nchiral magnetic field or anomalous Hall effect are nonvanishing in\nnonequilibrium or inhomogeneous systems. Our results advance efforts in\nunderstanding the anomalous transport in interacting non-Hermitian systems."
    },
    {
        "anchor": "Tunable Band Gap in Graphene with a Non-Centrosymmetric Superlattice\n  Potential: We show that, if graphene is subjected to the potential from an external\nsuperlattice, a band gap develops at the Dirac point provided the superlattice\npotential has broken inversion symmetry. As a numerical example, we calculate\nthe band structure of graphene in the presence of an external potential due to\nperiodically patterned gates arranged in a triangular graphene superlattice\n(TGS) with broken inversion symmetry, and find that a band gap is created at\nboth the original and \"second generation\" Dirac point. The gap can be\ncontrolled, in principle, by changing the external potential and the lattice\nconstant of the TGS.",
        "positive": "Shapiro-like Resonance in Ultracold Molecule Production via an\n  Oscillating Magnetic Field: We study the process of production of ultracold molecules from ultracold\natoms using a sinusoidally oscillating magnetic field modulation. When the\nmagnetic field is resonant roughly with the molecular binding energy,\nShapiro-like resonances are observed. Their resonance profiles are well fitted\nby the Lorentzian functions. The line widths depend on both the amplitude and\nthe duration of the applied modulations, and are found to be dramatically\nbroadened by thermal dephasing effect. The resonance centers shift due to both\nmany-body effect and finite temperature effect. Our theory is consistent with\nrecent experiment (S. T. Thompson, E. Hodby, and C. E. Wieman, Phys. Rev. Lett.\n95, 190404 (2005)). Our model predicts a 1/3 ceiling for the molecular\nproduction yield in uncondensed ultracold atomic clouds for a long coupling\ntime, while for the condensed atoms the optimal conversion yield could be\nbeyond the limit."
    },
    {
        "anchor": "Pseudo Dirac Nodal Sphere: Unusual Electronic Structure and Material\n  Realization: Topological semimetals (TSMs) in which conduction and valence bands cross at\nzero-dimensional (0D) Dirac nodal points (DNPs) or 1D Dirac nodal lines (DNLs),\nin 3D momentum space, have recently drawn much attention due to their exotic\nelectronic properties. Here we generalize the TSM state further to a\nhigher-symmetry and higher-dimensional pseudo Dirac nodal sphere (PDNS) state,\nwith the band crossings forming a 2D closed sphere at the Fermi level. The PDNS\nstate is characterized with a spherical backbone consisting of multiple\ncrossing DNLs while band degeneracy in between the DNLs is approximately\nmaintained by weak interactions. It exhibits some unique electronic properties\nand low-energy excitations, such as collective plasmons different from DNPs and\nDNLs. Based on crystalline symmetries, we theoretically demonstrate two\npossible types of PDNS states, and identify all the possible band crossings\nwith pairs of 1D irreducible representations to form the PDNS states in 32\npoint groups. Importantly, we discover that strained MH3 (M= Y, Ho, Tb, Nd) and\nSi3N2 are materials candidates to realize these two types of PDNS states,\nrespectively. As a high-symmetry-required state, the PDNS semimetal can be\nregarded as the \"parent phase\" for other topological gapped and gapless states.",
        "positive": "Spin-wave coupling to electromagnetic cavity fields in dysposium ferrite: Coupling of spin-waves with electromagnetic cavity field is demonstrated in\nan antiferromagnet, dysprosium ferrite (DyFeO3). By measuring transmission at\n0.2-0.35 THz and sweeping sample temperature, magnon-photon coupling signatures\nwere found at crossings of spin-wave resonances with Fabry-Perot cavity modes\nformed in samples. The obtained spectra are explained in terms of classical\nelectrodynamics and a microscopic model."
    },
    {
        "anchor": "Quantum Transport through Organic Molecules: We explore electron transport properties for the model of benzene-1,\n4-dithiolate (BDT) molecule and for some other geometric models of benzene\nmolecule attached to two semi-infinite one-dimensional metallic electrodes\nusing the Green's function formalism. An analytic approach, based on a simple\ntight-binding framework, is presented to describe electron transport through\nthe molecular wires. Electronic transport in such molecular systems is strongly\naffected by the geometry of the molecules as well as their coupling to the\nside-attached electrodes. Conductance reveals resonant peaks associated with\nthe molecular energy eigenstates providing several complex spectra. Current\npassing through the molecules shows staircase-like behavior with sharp steps in\nthe weak molecule-to-electrode coupling limit, while it varies quite\ncontinuously with the applied bias voltage in the limit of strong molecular\ncoupling. In the presence of transverse magnetic field, conductance exhibits\noscillatory behavior with flux $\\phi$, threaded by the molecular ring, showing\n$\\phi_0$ ($=ch/e$) flux-quantum periodicity. Though, conductance changes in the\npresence of transverse magnetic field, but the current-voltage characteristics\nare not significantly affected by this field.",
        "positive": "Confinement sensitivity in quantum dot singlet-triplet relaxation: Spin-orbit mediated phonon relaxation in a two-dimensional quantum dot is\ninvestigated using different confining potentials. Elliptical harmonic\noscillator and cylindrical well results are compared to each other in the case\nof a two-electron GaAs quantum dot subjected to a tilted magnetic field. The\nlowest energy set of two-body singlet and triplet states are calculated\nincluding spin-orbit and magnetic effects. These are used to calculate the\nphonon induced transition rate from the excited triplet to the ground state\nsinglet for magnetic fields up to where the states cross. The roll of the cubic\nDresselhaus effect and the positioning of \"spin hot-spots\" are discussed and\nrelaxation rates for a few different systems are exhibited."
    },
    {
        "anchor": "Giant Magnetoresistance Effect in Organic Material and Its Potential for\n  Magnetic Sensor: Giant magnetoresistance (GMR) material has great potential as next generation\nmagnetic field sensing devices, have magnetic properties and high electrical\npotential to be developed into various applications such as: magnetic field\nsensor measurements, current measurements, linear and rotational position\nsensor, data storage, head recording, and non-volatile magnetic random access\nmemory (MRAM). Today, the new GMR materials based on organic material obtained\nafter allowing for Organic Magnetoresistance (OMAR) was found in OLEDs (organic\nlight-emitting diodes). This organic material is used as a spacer layer in GMR\ndevices with spin-valve structures. Traditionally, metals and semiconductors\nare used as a spacer layer in spin-valve. However, several factors such as spin\nscattering caused by large atoms of the spacer material and the interface\nscattering of ferromagnetic with a spacer, will limit the efficiency of\nspin-valve. In this paper, we describe a new GMR materials based on organic\nmaterial that we have developed.",
        "positive": "Piezoresistivity and Strain-induced Band Gap Tuning in Atomically Thin\n  MoS2: The bandgap of MoS2 is highly strain-tunable which results in the modulation\nof its electrical conductivity and manifests itself as the piezoresistive\neffect while a piezoelectric effect was also observed in odd-layered MoS2 with\nbroken inversion symmetry. This coupling between electrical and mechanical\nproperties makes MoS2 a very promising material for nanoelectromechanical\nsystems (NEMS). Here we incorporate monolayer, bilayer and trilayer MoS2 in a\nnanoelectromechanical membrane configuration. We detect strain-induced band gap\ntuning via electrical conductivity measurements and demonstrate the emergence\nof the piezoresistive effect in MoS2. Finite element method (FEM) simulations\nare used to quantify the band gap change and to obtain a comprehensive picture\nof the spatially varying bandgap profile on the membrane. The piezoresistive\ngauge factor is calculated to be -148 +/- 19, -224 +/- 19 and -43.5 +/- 11 for\nmonolayer, bilayer and trilayer MoS2 respectively which is comparable to\nstate-of-the-art silicon strain sensors and two orders of magnitude higher than\nin strain sensors based on suspended graphene. Controllable modulation of\nresistivity in 2D nanomaterials using strain-induced bandgap tuning offers a\nnovel approach for implementing an important class of NEMS transducers,\nflexible and wearable electronics, tuneable photovoltaics and photodetection."
    },
    {
        "anchor": "Thermal-magnetic noise measurement of spin-torque effects on\n  ferromagnetic resonance in MgO-based magnetic tunnel junctions: Thermal-magnetic noise at ferromagnetic resonance (T-FMR) can be used to\nmeasure magnetic perpendicular anisotropy of nanoscale magnetic tunnel\njunctions (MTJs). For this purpose, T-FMR measurements were conducted with an\nexternal magnetic field up to 14 kOe applied perpendicular to the film surface\nof MgO-based MTJs under a dc bias. The observed frequency-field relationship\nsuggests that a 20 A CoFeB free layer has an effective demagnetization field\nmuch smaller than the intrinsic bulk value of CoFeB, with 4PiMeff = (6.1 +/-\n0.3) kOe. This value is consistent with the saturation field obtained from\nmagnetometry measurements on extended films of the same CoFeB thickness.\nIn-plane T-FMR on the other hand shows less consistent results for the\neffective demagnetization field, presumably due to excitations of more complex\nmodes. These experiments suggest that the perpendicular T-FMR is preferred for\nquantitative magnetic characterization of nanoscale MTJs.",
        "positive": "Comment on arXiv:1705.01165 by V. N. Premakumar, M. G. Vavilov and R.\n  Joynt: We comment on some aspects of the paper entitled \"Evanescent-wave Johnson\nnoise in small devices\" recently posted by V. N. Premakumar, M. G. Vavilov and\nR. Joynt."
    },
    {
        "anchor": "Possible charge-density-wave signatures in the anomalous resistivity of\n  Li-intercalated multilayer MoS2: We fabricate ion-gated field-effect transistors (iFET) on mechanically\nexfoliated multilayer MoS$_2$. We encapsulate the flake by Al$_2$O$_3$, leaving\nthe device channel exposed at the edges only. A stable Li$^+$ intercalation in\nthe MoS$_2$ lattice is induced by gating the samples with a Li-based polymeric\nelectrolyte above $\\sim$ 330 K and the doping state is fixed by quenching the\ndevice to $\\sim$ 300 K. This intercalation process induces the emergence of\nanomalies in the temperature dependence of the sheet resistance and its first\nderivative, which are typically associated with structural/electronic/magnetic\nphase transitions. We suggest that these anomalies in the resistivity of\nMoS$_2$ can be naturally interpreted as the signature of a transition to a\ncharge-density-wave phase induced by lithiation, in accordance with recent\ntheoretical calculations.",
        "positive": "Non-adiabatic electron dynamics in time-dependent density-functional\n  theory: Time-dependent density-functional theory (TDDFT) treats dynamical exchange\nand correlation (xc) via a single-particle potential, Vxc(r,t), defined as a\nnonlocal functional of the density n(r',t'). The popular adiabatic\nlocal-density approximation (ALDA) for Vxc(r,t) uses only densities at the same\nspace-time point (r,t). To go beyond the ALDA, two local approximations have\nbeen proposed based on quantum hydrodynamics and elasticity theory: (a) using\nthe current as basic variable (C-TDDFT) [G. Vignale, C. A. Ullrich, and S.\nConti, Phys. Rev. Lett. 79, 4878 (1997)], (b) working in a co-moving Lagrangian\nreference frame (L-TDDFT) [I. V. Tokatly, Phys. Rev. B 71, 165105 (2005)]. This\npaper illustrates, compares, and analyzes both non-adiabatic theories for\nsimple time-dependent model densities in the linear and nonlinear regime, for a\nbroad range of time and frequency scales. C- and L-TDDFT are identical in\ncertain limits, but in general exhibit qualitative and quantitative differences\nin their respective treatment of elastic and dissipative electron dynamics. In\nsituations where the electronic density rapidly undergoes large deformations,\nit is found that non-adiabatic effects can become significant, causing the ALDA\nto break down."
    },
    {
        "anchor": "Kondo effect in triple quantum dots: Numerical analysis of the simplest odd-numbered system of coupled quantum\ndots reveals an interplay between magnetic ordering, charge fluctuations and\nthe tendency of itinerant electrons in the leads to screen magnetic moments.\nThe transition from local-moment to molecular-orbital behavior is visible in\nthe evolution of correlation functions as the inter-dot coupling is increased.\nResulting novel Kondo phases are presented in a phase diagram which can be\nsampled by measuring the zero-bias conductance. We discuss the origin of the\neven-odd effects by comparing with the double quantum dot.",
        "positive": "Magnetization of superparamagnetics in the state of mechanical\n  anisotropy: The internal energy of magnetic anisotropy for some nanoparticles dominates\nover the thermal energy even at room temperature. Strong magnetic anisotropy of\nnanoparticles can significantly affect the process of magnetization of the\nmagnetic fluid. This influence is substantial if the system of nanoparticles is\nin a state of mechanical anisotropy in which the anisotropy axes of the\nparticles have the same direction. In this work, it is shown that the\nmagnetization curve of the magnetic fluid in a state of mechanical anisotropy\nis significantly different from that of Langevin. It is located between the\nLangevin and hyperbolic tangent curves and with increasing anisotropy takes\nprogressively the hyperbolic tangent shape. It is also shown that in case of\npowder samples, the mechanical anisotropy leads to substantial quantitative\nchanges in the Curie law."
    },
    {
        "anchor": "FRET distance dependence from upconverting nanoparticles to quantum dots: F\\\"orster resonant energy transfer (FRET) with upconverting nanoparticles\n(UCNPs) as donors and quantum dots (QDs) as acceptors has been regarded as a\npromising tool for biosensing applications. In this work, we use time-resolved\nfluorescence spectroscopy to analyze the UCNP-to-QD FRET and we focus on the\nmost relevant parameter of the FRET phenomenon, UCNP-QD distance. This distance\nis controlled by a nanometric silica shell around the UCNP surface. We\ntheoretically reproduce the experimental results applying FRET theory to the\ndistribution of emitting erbium ions in the UCNP. This simple model allows us\nto estimate the contribution of every erbium ion to the final FRET response and\nto explore different strategies to improve FRET efficiency.",
        "positive": "p-GaAs nanowire MESFETs with near-thermal limit gating: Difficulties in obtaining high-performance p-type transistors and gate\ninsulator charge-trapping effects present two major challenges for III-V\ncomplementary metal-oxide semiconductor (CMOS) electronics. We report a p-GaAs\nnanowire metal-semiconductor field-effect transistor (MESFET) that eliminates\nthe need for a gate insulator by exploiting the Schottky barrier at the\nmetal-GaAs interface. Our device beats the best-performing p-GaSb nanowire\nmetal-oxide-semiconductor field effect transistor (MOSFET), giving a typical\nsub-threshold swing of 62 mV/dec, within 4% of the thermal limit, on-off ratio\n$\\sim 10^{5}$, on-resistance ~700 k$\\Omega$, contact resistance ~30 k$\\Omega$,\npeak transconductance 1.2 $\\mu$S/$\\mu$m and high-fidelity ac operation at\nfrequencies up to 10 kHz. The device consists of a GaAs nanowire with an\nundoped core and heavily Be-doped shell. We carefully etch back the nanowire at\nthe gate locations to obtain Schottky-barrier insulated gates whilst leaving\nthe doped shell intact at the contacts to obtain low contact resistance. Our\ndevice opens a path to all-GaAs nanowire MESFET complementary circuits with\nsimplified fabrication and improved performance."
    },
    {
        "anchor": "Photoluminescence decomposition analysis: a technique to characterize NV\n  creation in diamond: Treatment of lab-grown diamond by electron irradiation and annealing has\nenabled quantum sensors based on negatively-charged nitrogen-vacancy\n(NV$^\\text{-}$) centers to demonstrate record sensitivities.\n\\cite{Clevenson2015,Wolf2015,Barry2016,Chatzidrosos2017}. Here we investigate\nthe irradiation and annealing process applied to 28 diamond samples using a new\nambient-temperature, all-optical approach. As the presence of the\nneutrally-charged nitrogen-vacancy (NV$^\\text{0}$) center is deleterious to\nsensor performance, this photoluminescence decomposition analysis (PDA) is\nfirst employed to determine the concentration ratio of NV$^\\text{-}$ to NV$^0$\nin diamond samples from the measured photoluminescence spectrum. The analysis\nhinges on (i) isolating each NV charge state's emission spectrum and (ii)\nmeasuring the NV$^\\text{-}$ to NV$^0$ emission ratio, which is found to be\n2.5$\\pm$0.5 under low-intensity 532 nm illumination. Using the PDA method, we\nmeasure the effects of irradiation and annealing on conversion of\nsubstitutional nitrogen to NV centers. Combining these measurements with a\nphenomenological model for diamond irradiation and annealing, we extract an\nestimated monovacancy creation rate of $0.52\\pm 0.26$ cm$^{\\text{-1}}$ for 1\nMeV electron irradiation and an estimated monovacancy diffusion coefficient of\n1.8 nm$^2$/s at 850~$^\\circ$C. Finally we find that irradiation doses $\\gtrsim\n10^{18}$ e$^\\text{-}$/cm$^2$ deteriorate the NV$^\\text{-}$ decoherence time\n$T_2$ whereas $T_1$ is unaffected up to the the maximum investigated dose of\n$5\\times 10^{18}$ e$^\\text{-}$/cm$^2$.",
        "positive": "Strained bilayer graphene: Band structure topology and Landau level\n  spectrum: We show that topology of the low-energy band structure in bilayer graphene\ncritically depends on mechanical deformations of the crystal which may easily\ndevelop in suspended graphene flakes. We describe the Lifshitz transition that\ntakes place in strained bilayers upon splitting the parabollic bands at\nintermediate energies into several Dirac cones at the energy scale of few meV.\nThen, we show how this affects the electron Landau level spectra and the\nquantum Hall effect."
    },
    {
        "anchor": "Magnetic field-enhanced spin filtering in rare-earth mononitride tunnel\n  junctions: Spin filter tunnel junctions are based on selective tunneling of up and down\nspin electrons controlled through exchange splitting of the band structure of a\nferromagnetic insulator. Therefore, spin filter efficiency can be tuned by\nadjusting exchange strength of the tunnel barrier. We have observed that\nmagnetic field and bias voltage (current) can be used to regulate exchange\nstrength and consequently spin-filter efficiency in tunnel junctions with\nferromagnetic DyN and GdN tunnel barrier. In tunnel junctions with DyN barrier\nwe obtained $\\sim$37$\\%$ spin polarization of tunneling electrons at 11 K due\nto a small exchange splitting ($ E_{ex}$) $\\approx$5.6 meV of the barrier\nheight ($\\Phi _0$) $\\approx$60 meV. Huge spin-filter efficiency $\\sim$97$\\%$\nwas found for tunnel junctions with GdN barrier due to larger $E_{ex}$\n$\\approx$47 meV. In the presence of an applied magnetic field, barrier height\ncan further split due to magnetic field dependent exchange splitting $\nE_{ex}(H)$. The spin filter efficiency in DyN tunnel junctions can be increased\nup to $\\sim$87$\\%$ with magnetic field. Electric and magnetic field tuned\nspin-filter efficiency of these tunnel junctions gives opportunity for\npractical application of these devices with additional functionality.",
        "positive": "Singlet-triplet avoided crossings and effective $g$ factor versus\n  spatial orientation of spin-orbit-coupled quantum dots: We study avoided crossings opened by spin-orbit interaction in the energy\nspectra of one- and two-electron anisotropic quantum dots in perpendicular\nmagnetic field. We find that for simultaneously present Rashba and Dresselhaus\ninteractions the width of avoided crossings and the effective $g$ factor depend\non the dot orientation within (001) crystal plane. The extreme values of these\nquantities are obtained for [110] and [1$\\bar{1}$0] orientations of the dot.\nThe width of singlet-triplet avoided crossing changes between these two\norientations by as much as two orders of magnitude. The discussed modulation\nresults from orientation-dependent strength of the Zeeman interaction which\ntends to polarize the spins in the direction of the external magnetic field and\nthus remove the spin-orbit coupling effects."
    },
    {
        "anchor": "High-Q Tantalum Oxide Nanomechanical Resonators by Laser-Oxidation of\n  TaSe2: Controlling the strain in two-dimensional materials is an interesting avenue\nto tailor the mechanical properties of nanoelectromechanical systems. Here we\ndemonstrate a technique to fabricate ultrathin tantalum oxide nanomechanical\nresonators with large stress by laser-oxidation of nano-drumhead resonators\nmade out of tantalum diselenide (TaSe2), a layered 2D material belonging to the\nmetal dichalcogenides. Prior to the study of their mechanical properties with a\nlaser interferometer, we checked the oxidation and crystallinity of the\nfreely-suspended tantalum oxide in a high-resolution electron microscope. We\nshow that the stress of tantalum oxide resonators increase by 140 MPa (with\nrespect to pristine TaSe2 resonators) which causes an enhancement of quality\nfactor (14 times larger) and resonance frequency (9 times larger) of these\nresonators.",
        "positive": "Phase-locked magnetoconductance oscillations as a probe of Majorana edge\n  states: We calculate the Andreev conductance of a superconducting ring interrupted by\na flux-biased Josephson junction, searching for electrical signatures of\ncirculating edge states. Two-dimensional pair potentials of spin-singlet d-wave\nand spin-triplet p-wave symmetry support, respectively, (chiral) Dirac modes\nand (chiral or helical) Majorana modes. These produce h/e-periodic\nmagnetoconductance oscillations of amplitude \\simeq (e^{2}/h)N^{-1/2}, measured\nvia an N-mode point contact at the inner or outer perimeter of the grounded\nring. For Dirac modes the oscillations in the two contacts are independent,\nwhile for an unpaired Majorana mode they are phase locked by a topological\nphase transition at the Josephson junction."
    },
    {
        "anchor": "Berry curvature-induced local spin polarisation in gated\n  graphene/WTe$_2$ heterostructures: Full experimental control of local spin-charge interconversion is of primary\ninterest for spintronics. Heterostructures combining graphene with a strongly\nspin-orbit coupled two-dimensional (2D) material enable such functionality by\ndesign. Electric spin valve experiments have provided so far global information\non such devices, while leaving the local interplay between symmetry breaking,\ncharge flow across the heterointerface and aspects of topology unexplored.\nHere, we utilize magneto-optical Kerr microscopy to resolve the gate-tunable,\nlocal current-induced spin polarisation in graphene/WTe$_2$ van der Waals (vdW)\nheterostructures. It turns out that even for a nominal in-plane transport,\nsubstantial out-of-plane spin accumulation is induced by a corresponding\nout-of-plane current flow. We develop a theoretical model which explains the\ngate- and bias-dependent onset and spatial distribution of the massive Kerr\nsignal on the basis of interlayer tunnelling, along with the reduced point\ngroup symmetry and inherent Berry curvature of the heterostructure. Our\nfindings unravel the potential of 2D heterostructure engineering for harnessing\ntopological phenomena for spintronics, and constitute an important further step\ntoward electrical spin control on the nanoscale.",
        "positive": "Terahertz radiation from accelerating charge carriers in graphene under\n  ultrafast photoexcitation: We study the generation of THz radiation from the acceleration of ultrafast\nphotoexcited charge carriers in graphene in the presence of a DC electric\nfield. Our model is based on calculating the transient current density from the\ntime-dependent distribution function which is determined using the Boltzmann\ntransport equation within a relaxation time approximation. We include the\ntime-dependent generation of carriers by the pump pulse by solving for the\ncarrier generation rate using the Bloch equations in the rotating wave\napproximation (RWA). The linearly polarized pump pulse generates an anisotropic\ndistribution of photoexcited carriers in the $k_x-k_y$ plane. The collision\nintegral in the Boltzmann equation includes a term that leads to the\n\\textit{thermalization} of carriers via carrier-carrier scattering to an\neffective temperature above the lattice temperature, as well as a\n\\textit{cooling} term which leads to energy relaxation via inelastic\ncarrier-phonon scattering. The radiated signal is proportional to the time\nderivative of the transient current density. In spite of the fact that the\nmagnitude of the velocity is the same for all the carriers in graphene, there\nis still emitted radiation from the photoexcited charge carriers with frequency\ncomponents in the THz range due to a change in the \\textit{direction} of\nvelocity of the photoexcited carriers in the external electric field as well as\n\\textit{cooling} of the photoexcited carriers on a sub-picosecond time scale."
    },
    {
        "anchor": "Thermal Transport Across Metal Silicide-Silicon Interfaces: An\n  Experimental Comparison between Epitaxial and Non-epitaxial Interfaces: Silicides are used extensively in nano- and microdevices due to their low\nelectrical resistivity, low contact resistance to silicon, and their process\ncompatibility. In this work, the thermal interface conductance of TiSi$_2$,\nCoSi$_2$, NiSi and PtSi are studied using time-domain thermoreflectance.\nExploiting the fact that most silicides formed on Si(111) substrates grow\nepitaxially, while most silicides on Si(100) do not, we study the effect of\nepitaxy, and show that for a wide variety of interfaces there is no difference\nin the thermal interface conductance of epitaxial and non-epitaxial\nsilicide/silicon interfaces. The effect of substrate carrier concentration is\nalso investigated over a wide range of p- and n-type doping, and is found to be\nindependent of carrier concentration, regardless of whether the interface is\nepitaxial and regardless of silicide type. In the case of epitaxial CoSi$_2$, a\ncomparison of temperature dependant experimental data is made with two detailed\ncomputational models using (1) full-dispersion diffuse mismatch modeling (DMM)\nincluding the effect of near-interfacial strain and (2) an atomistic Green'\nfunction (AGF) approach that integrates near-interface changes in the\ninteratomic force constants obtained through density functional perturbation\ntheory. At temperatures above 100K, the AGF approach greatly underpredicts the\nCoSi$_2$ data, while the DMM prediction matches the data well. The\nfull-dispersion DMM is also found to closely predict the experimentally\nobserved temperature-dependent interface conductance for epitaxial NiSi/Si and\nnon-epitaxial TiSi$_2$/Si interfaces. In the case of epitaxial PtSi/Si\ninterfaces, full dispersion DMM significantly overpredicts the experimental\ndata.",
        "positive": "On the gauge invariant and topological nature of the localization\n  determining the Quantum Hall Effect plateaus: It is shown how the electromagnetic response of the 2DEG under Quantumm Hall\nEffect regime, chracterized by the Chern-Simons topological action, transforms\nthe sample impurities and defects in charge reservoirs that stabilize the the\nHall conductivity plateaus. The results, determine the basic dynamical origin\nof the singular properties of localization under the occurrence of the QHE\nobtained in the pioneering works of Laughlin and of Joynt and Prange, by means\nof a gauge invariance argument and a purely electronic analysis, respectively.\nThe common picture of electrons moving the equipotential lines gets an\nanalytical realization through the Chern-Simons current and charge densities."
    },
    {
        "anchor": "Optomechanical microwave amplification without mechanical amplification: High-gain and low-noise signal amplification is a valuable tool in various\ncryogenic microwave experiments. A microwave optomechanical device, in which a\nvibrating capacitor modulates the frequency of a microwave cavity, is one\ntechnique that is able to amplify microwave signals with high gain and large\ndynamical range. Such optomechanical amplifiers typically rely on strong\nbackaction of microwave photons on the mechanical mode achieved in the\nsideband-resolved limit of optomechanics. Here, we observe microwave\namplification in an optomechanical cavity in the extremely unresolved sideband\nlimit. A large gain is observed for any detuning of the single pump tone within\nthe cavity linewidth, a clear indication that the amplification is not induced\nby dynamical backaction. By being able to amplify for any detuning of the pump\nsignal, the amplification center frequency can be tuned over the entire range\nof the broad cavity linewidth. Additionally, by providing microwave\namplification without mechanical amplification, we predict that using this\nscheme it is possible to achieve near-quantum-limited microwave amplification\ndespite a large thermal occupation of the mechanical mode.",
        "positive": "A study of quantum pseudodot system with a two-dimensional\n  pseudoharmonic potential using Nikiforov-Uvarov method: We use the Nikiforov-Uvarov method to calculate the bound states (energy\nspectra and wave functions) of a two-dimensional (2D) electron gas interacted\nwith an exactly solvable pseudoharmonic confinement potential in a strong\nuniform magentic field inside dot and Aharonov-Bohm flux field inside a\npseudodot. We give a unified treatment for both Schr\\\"odinger and spin-0\nKlein-Gordon energy spectrum and wave functions as functions of chemical\npotential parameter, magnetic field strength, AB flux field and magnetic\nquantum number. We obtain analytic expression for the light interband\nabsorption coefficient and threshold frequency of absorption as functions of\napplied magnetic field and geometrical size of quantum pseudodot. The\ntemperature dependence energy levels for GaAs are also calculated."
    },
    {
        "anchor": "Spin-orbit coupling effects in one-dimensional ballistic quantum wires: We study the spin-dependent electronic transport through a one-dimensional\nballistic quantum wire in the presence of Rashba spin-orbit interaction. In\nparticular, we consider the effect of the spin-orbit interaction resulting from\nthe lateral confinement of the two-dimensional electron gas to the\none-dimensional wire geometry. We generalize a situation suggested earlier [P.\nStreda and P. Seba, Phys. Rev. Lett. 90, 256601 (2003)] which allows for\nspin-polarized electron transport. As a result of the lateral confinement, the\nspin is rotated out of the plane of the two-dimensional system. We furthermore\ninvestigate the spin-dependent transmission and the polarization of an electron\ncurrent at a potential barrier. Finally, we construct a lattice model which\nshows similar low-energy physics. In the future, this lattice model will allow\nus to study how the electron-electron interaction affects the transport\nproperties of the present setup.",
        "positive": "Nanostructured and Modulated Low-Dimensional Systems: Charge density wave (CDW) ordering in NbSe3 and the structurally related\nquasi one-dimensional compounds is reconsidered. Since the modulated ground\nstate is characterized by unstable nano-domains, the structural information\nobtained from diffraction experiments is to be supplemented by some additional\ninformation from a method, able to reveal details on a unit cell level.\nLow-temperature (LT) scanning tunneling microscopy (STM) can resolve both, the\nlocal atomic structure and the superimposed charge density modulation. It is\nshown that the established model for NbSe3 with two incommensurate (IC) modes,\nq1 = (0,0.241,0) and q2 = (0.5,0.260,0.5), locked in at T1=144K and T2=59K and\nseparately confined to two of the three available types of bi-capped trigonal\nprismatic (BCTP) columns, must be modified. The alternative explanation is\nbased on the existence of modulated layered nano-domains and is in good accord\nwith the available LT STM results. These confirm i.a. the presence of both IC\nmodes above the lower CDW transition temperature. Two BCTP columns, belonging\nto a symmetry-related pair, are as a rule alternatively modulated by the two\nmodes. Such pairs of columns are ordered into unstable layered nano-domains,\nwhose q1 and q2 sub-layers are easily interchanged. The mutually\ninterchangeable sections of the two unstable IC modes keep a temperature\ndependent long-range ordering. Both modes can formally be replaced by a single\nhighly inharmonic long-period commensurate CDW."
    },
    {
        "anchor": "On topological aspects of 2D graphene like materials: We study the graphene lattice with a curvature effect. The action depicting\nmultilayers of graphene is portrayed in curved spacetime and effective Dirac\nequation scopes the curvature effect. The magnetic field is responsible for the\ngeometric variations and these changes are identified as topological aspects in\ngraphene. By varying the geometry of the graphene one can create topologically\ndistinct surfaces which could be remarked as torus or sphere. The 2D hexagonal\ntessellation induces a curvature effect and the tessellation plane is reduced\nto a 2-torus having genus g=1.",
        "positive": "Designing Electron Spin Textures and Spin Interferometers by Shape\n  Deformations: We demonstrate that the spin orientation of an electron propagating in a\none-dimensional nanostructure with Rashba spin-orbit (SO) coupling can be\nmanipulated on demand by changing the geometry of the nanosystem. Shape\ndeformations that result in a non-uniform curvature give rise to complex\nthree-dimensional spin textures in space. We employ the paradigmatic example of\nan elliptically deformed quantum ring to unveil the way to get an\nall-geometrical and all-electrical control of the spin orientation. The\nresulting spin textures exhibit a tunable topological character with windings\naround the radial and the out-of-plane directions. We show that these\ntopologically non trivial spin patterns affect the spin interference effect in\nthe deformed ring, thereby resulting in different geometry-driven ballistic\nelectronic transport behaviors. Our results establish a deep connection between\nelectronic spin textures, spin transport and the nanoscale shape of the system."
    },
    {
        "anchor": "Voltage dependence of Landau-Lifshitz-Gilbert damping of a spin in a\n  current driven tunnel junction: We present a theory of Landau-Lifshitz-Gilbert damping $\\alpha$ for a\nlocalized spin ${\\vec S}$ in the junction coupled to the conduction electrons\nin both leads under an applied volatege $V$. We find the voltage dependence of\nthe damping term reflecting the energy dependence of the density of states. We\nfind the effect is linear in the voltage and cotrolled by particle-hole\nasymmetry of the leads.",
        "positive": "Current enhancement due to field-induced dark carrier multiplication in\n  graphene: We present a microscopic study on current generation in graphene in response\nto an electric field. While scattering is generally considered to reduce the\ncurrent, we reveal that in graphene Auger processes give rise to a current\nenhancement via a phenomenon we denote dark carrier multiplication. Based on a\nmicroscopic approach, we show that, if other scattering channels are absent,\nthis prevents the carrier distribution to reach a stationary value. Taking into\naccount scattering with phonons a finite current is restored, however its value\nexceeds the stationary current without scattering."
    },
    {
        "anchor": "Universal decay cascade model for dynamic quantum dot initialization: Dynamic quantum dots can be formed by time-dependent electrostatic potentials\nin nanoelectronic devices, such as gate- or surface-acoustic-wave-driven\nelectron pumps. Ability to control the number of captured electrons with high\nprecision is required for applications in fundamental metrology and quantum\ninformation processing. In this work we propose and quantify a scheme to\ninitialize quantum dots with a controllable number of electrons. It is based on\nthe stochastic decrease in the electron number of a shrinking dynamic quantum\ndot and is described by a nuclear decay cascade model with \"isotopes\" being\ndifferent charge states of the dot. Unlike the natural nuclei, the artificial\nconfinement is time-dependent and tunable, so the probability distribution for\nthe final \"stable isotopes\" depends on the external gate voltage. We derive an\nexplicit fitting formula to extract the sequence of decay rate ratios from the\nmeasurements of averaged current in a periodically driven device. This provides\na device-specific fingerprint which allows to compare different devices and\narchitectures, and predict the upper limits of initialization accuracy from low\nprecision measurements.",
        "positive": "Paramagnetic singularities of the orbital magnetism in graphene with a\n  moir\u00e9 potential: The recent detection of the singular diamagnetism of Dirac electrons in a\nsingle graphene layer paved a new way of probing 2D quantum materials through\nthe measurement of equilibrium orbital currents which cannot be accessed in\nusual transport experiments. Among the theoretical predictions is an intriguing\norbital paramagnetism at saddle points of the dispersion relation. Here we\npresent magnetisation measurements in graphene monolayers aligned on hexagonal\nboron nitride (hBN)crystals. Beside the sharp diamagnetic McClure response at\nthe Dirac point, we detect extra diamagnetic singularities at the satellite\nDirac points (sDP) of the moir\\'e lattice. Surrounding these diamagnetic\nsatellite peaks, we also observe paramagnetic peaks located at the chemical\npotential of the saddle points of the Graphene moir\\'e band structure and\nrelate them to the presence of van Hove logarithmic singularities in the\ndensity of states. These findings reveal the long ago predicted anomalous\nparamagnetic orbital response in 2D systems when the Fermi energy is tuned to\nthe vicinity of saddle points."
    },
    {
        "anchor": "Zero-Point Fluctuations and the Quenching of the Persistent Current in\n  Normal Metal Rings: The ground state of a phase-coherent mesoscopic system is sensitive to its\nenvironment. We investigate the persistent current of a ring with a quantum dot\nwhich is capacitively coupled to an external circuit with a dissipative\nimpedance. At zero temperature, zero-point quantum fluctuations lead to a\nstrong suppression of the persistent current with decreasing external\nimpedance. We emphasize the role of displacement currents in the dynamical\nfluctuations of the persistent current and show that with decreasing external\nimpedance the fluctuations exceed the average persistent current.",
        "positive": "Spin-transport in superconductors: Spin-transport in superconductors is a subject of fundamental and technical\nimportance with the potential for applications in superconducting-based\ncryogenic memory and logic. Research in this area is rapidly intensifying with\nrecent discoveries establishing the field of superconducting spintronics. In\nthis perspective we provide an overview of the experimental state-of-the-art\nwith a particular focus on local and nonlocal spin-transport in\nsuperconductors, and propose device schemes to demonstrate the viability of\nsuperconducting spin-based devices."
    },
    {
        "anchor": "Dynamical polarization and plasmons in a two-dimensional system with\n  merging Dirac points: We have studied the dynamical polarization and collective excitations in an\nanisotropic two-dimensional system undergoing a quantum phase transition with\nmerging of two Dirac points. Analytical results for the one-loop polarization\nfunction are obtained at the finite momentum, frequency, and chemical\npotential. The evolution of the plasmon dispersion across the phase transition\nis then analyzed within the random phase approximation. We derive analytically\nthe long-wavelength dispersion of the undamped anisotropic collective mode and\nfind that it evolves smoothly at the critical merging point. The effects of the\nvan Hove singularity on the plasmon excitations are explored in detail.",
        "positive": "Breakdown of the topological protection by cavity vacuum fields in the\n  integer quantum Hall effect: The control of the electronic properties of materials via the vacuum fields\nof cavity electromagnetic resonators is one of the emerging frontiers of\ncondensed matter physics. We show here that the enhancement of vacuum field\nfluctuations in subwavelength split-ring resonators dramatically affects\narguably one of the most paradigmatic quantum protectorates, namely the quantum\nHall electron transport in high-mobility 2D electron gases. The observed\nbreakdown of the topological protection of the integer quantum Hall effect is\ninterpreted in terms of a long-range cavity-mediated electron hopping where the\nanti-resonant terms of the light-matter coupling finally result into a finite\nresistivity induced by the vacuum fluctuations. The present experimental\nplatform can be used for any 2D material and provides new ways to manipulate\nelectron phases in matter thanks to vacuum-field engineering"
    },
    {
        "anchor": "All \"Magic Angles\" Are \"Stable\" Topological: We show that the electronic structure of the low-energy bands in the small\nangle-twisted bilayer graphene consists of a series of semi-metallic and\ntopological phases. In particular we are able to prove, using an approximate\nlow-energy particle-hole symmetry, that the gapped set of bands that exist\naround all magic angles has what we conjecture to be a stable topological index\nstabilized by a magnetic symmetry and reflected in the odd winding of the\nWilson loop in the Moir\\'e BZ. The approximate, emergent particle-hole symmetry\nis essential to the topology of graphene: when strongly broken, non-topological\nphases can appear. Our paper underpins topology as the crucial ingredient to\nthe description of low-energy graphene. We provide a $4$-band short range\ntight-binding model whose $2$ lower bands have the same topology, symmetry, and\nflatness as those of the twisted graphene, and which can be used as an\neffective low-energy model. We then perform large-scale ($11000$ atoms per unit\ncell, 40 days per $\\bf k$-point computing time) ab-initio calculations of a\nseries of small angles, from $3^\\circ$ to $1^\\circ$, which show a more complex\nand somewhat qualitatively different evolution of the symmetry of the\nlow-energy bands than that of the theoretical Moir\\'e model, but which confirms\nthe topological nature of the system. At certain angles, we find no insulating\nfilling in graphene at $-4$ electrons per Moir\\'e unit cell. The ab-initio\nevolution of gaps tends to differ from that of the continuum Moir\\'e model.",
        "positive": "Large vortex state in ferromagnetic disks: Magnetic vortices in soft ferromagnetic nano-disks have been extensively\nstudied for at least several decades both for their fundamental (as a \"live\"\nmacroscopic realization of a field theory model of an elementary particle) as\nwell as applied value for high-speed high-density power-independent information\nstorage. Here it is shown that there is another stable vortex state with large\nthickness-dependent core profile in nano-scale ferromagnetic disks of several\nexchange lengths in size. Its energy is computed numerically (in the framework\nof Magnetism@home distributed computing project) and its stability is studied\nanalytically, which allows to plot it on magnetic phase diagram. In cylinders\nof certain geometries large vortices exist on par with classical ones, while\nbeing separated by an energy barrier, controllable by tuning the geometry and\nmaterial of ferromagnetic disk. They can be an excellent candidate for magnetic\ninformation storage not only because the resulting disk sizes are among the\nsmallest, able to support magnetic vortices, but also because it is the closest\nto the classical vortex state of all other known metastable states of magnetic\nnano-cylinder. It means that memory, based on switching between these two types\nof magnetic vortices, may, potentially, achieve the highest possible rate of\nswitching."
    },
    {
        "anchor": "An Algebraic Approach to Electron Interactions in Quantum Hall Systems: Let $m$ denote the number of quasielectrons (QEs) in a quantum Hall system\ncontaining $N$ particles altogether. We show in several general cases that for\nsystems containing $m$ QEs in a single angular momentum shell above $N-m$\nFermions in an incompressible quantum liquid (IQL) state having filling factor\n$\\nu=\\frac{1}{3}$ that there always exists a configuration whose symmetric\ncorrelation function $G$ is nonzero. This extends recent comparable results\nconcerning the IQL state. As a consequence, one can obtain (explicitly) a\nconfiguration having a nonzero $G$ for all $N=8$ particle systems containing\nany number of QEs. To establish our result, we construct a family of\nmulti-graphs on $N$ vertices satisfying certain restraints on the degrees of\nthe vertices and possessing the property that whenever one computes the linear\nsymmetrization of the graph monomial of any member of the family, the result is\nalways nonzero. The nonzero linear symmetrization that is obtained in each case\nis in fact an example of what is called a relative semi-invariant of a\n(generic) binary form of degree $N$. Thus, in addition to providing new\ncorrelation functions for systems of interacting Fermions containing QEs, our\nconstruction could be of interest from both the invariant and graph theoretic\nstandpoints.",
        "positive": "Magnetotransport due to conductivity fluctuations in non-magnetic ZrTe2\n  nanoplates: Transition metal dichalcogenides with nontrivial band structures exhibit\nvarious fascinating physical properties and have sparked intensively research\ninterest. Here, we performed systematic magnetotransport measurements on\nmechanical exfoliation prepared ZrTe2 nanoplates. We revealed that the negative\nlongitudinal magnetoresistivity observed at high field region in the presence\nof parallel electric and magnetic fields could stem from the conductivity\nfluctuations due to the excess Zr in the nanoplates. In addition, the\nparametric plot, the planar Hall resistivity as function of the in-plane\nanisotropic magnetoresistivity, has an ellipse-shaped pattern with shifted\norbital center, which further strengthen the evidence for the conductivity\nfluctuations. Our work provides some useful insights into transport phenomena\nin topological materials."
    },
    {
        "anchor": "Emergence of Frohlich polaron from interlayer electron-phonon coupling\n  in van der Waals heterostructure: Van der Waals heterostructures, vertical stacks of layered materials, offer\nnewopportunities for novel quantum phenomena which are absent in their\nconstituent components. Here we report the emergence of polaron quasiparticles\nat the interface of graphene/hexagonal boron nitride (h-BN) heterostructures.\nUsing nanospot angle-resolved photoemission spectroscopy, we observe\nzone-corner replicas of h-BN valence band maxima, with energy spacing\ncoincident with the highest phonon energy of the heterostructure|an indication\nof Fr\u007fohlich polaron formation due to forward scattering electron-phonon\ncoupling. Parabolic fitting of the h-BN bands yields an effective mass\nenhancement of ~ 2.3, suggesting an intermediate coupling strength. Our\ntheoretical simulations based on Migdal-Eliashberg theory corroborate the\nexperimental results, allowing the extraction of microscopic physical\nparameters. Moreover,renormalisation of graphene $\\pi$ band is observed due to\nthe hybridisation with the h-BN band. Our work generalises the polaron study\nfrom transition metal oxides to Van derWaals heterostructures with higher\nmaterial exibility, highlighting interlayer coupling as an extra degree of\nfreedom to explore emergent phenomena.",
        "positive": "Unconventional spin currents in magnetic films: A spin current - a flow of spin angular momentum - can be carried either by\nspin polarised free electrons or by magnons, the quanta of a moving collective\noscillation of localised electron spins - a spin wave. Traditionally, it was\nassumed, that a spin wave in a magnetic film with spin-sink-free surfaces can\ntransfer energy and angular momentum only along its propagation direction. In\nthis work, using Brillouin light scattering spectroscopy in combination with a\ntheory of dipole-exchange spin-wave spectra, we show that in obliquely\nmagnetized free magnetic films the in-plane propagation of spin waves is\naccompanied by a transverse spin current along the film normal without any\ncorresponding transverse transport of energy."
    },
    {
        "anchor": "Spin transport-induced damping of coherent THz spin dynamics in iron: We study the damping of perpendicular standing spin-waves (PSSWs) in\nultrathin Fe films at frequencies up to 2.4 THz. The PSSWs are excited by\noptically generated ultrashort spin current pulses, and probed optically in the\ntime domain. Analyzing the wavenumber and thickness dependence of the damping,\nwe demonstrate that at sufficiently large wave vectors $k$ the damping is\ndominated by spin transport effects scaling with k^4 and limiting the frequency\nrange of observable PSSWs. Although this contribution is known to originate in\nthe spin diffusion, we argue that at moderate and large k a more general\ndescription is necessary and develop a model where the 'transverse spin mean\nfree path' is the a key parameter, and estimate it to be ~0.5 nm.",
        "positive": "Single-photon pump by Cooper-pair splitting: Hybrid quantum dot-oscillator systems have become attractive platforms to\ninspect quantum coherence effects at the nanoscale. Here, we investigate a\nCooper-pair splitter setup consisting of two quantum dots, each linearly\ncoupled to a local resonator. The latter can be realized either by a microwave\ncavity or a nanomechanical resonator. Focusing on the subgap regime, we\ndemonstrate that cross-Andreev reflection, through which Cooper pairs are split\ninto both dots, can efficiently cool down simultaneously both resonators into\ntheir ground state. Moreover, we show that a nonlocal heat transfer between the\ntwo resonators is activated when opportune resonance conditions are matched.\nThe proposed scheme can act as a heat-pump device with potential applications\nin heat control and cooling of mesoscopic quantum resonators."
    },
    {
        "anchor": "Machine learning Majorana nanowire disorder landscape: We develop a practical machine learning approach to determine the disorder\nlandscape of Majorana nanowires by using training of the conductance matrix and\ninverting the conductance data in order to obtain the disorder details in the\nsystem. The inversion carried out through machine learning using different\ndisorder parametrizations turns out to be unique in the sense that any input\ntunnel conductance as a function of chemical potential and Zeeman energy can\nindeed be inverted to provide the correct disorder landscape. Our work opens up\na qualitatively new direction of directly determining the topological invariant\nand the Majorana wave-function structure corresponding to a transport profile\nof a device using simulations that quantitatively match the specific\nconductance profile. In addition, this also opens up the possibility for\noptimizing Majorana systems by figuring out the (generally unknown) underlying\ndisorder only through the conductance data. An accurate estimate of the\napplicable spin-orbit coupling in the system can also be obtained within the\nsame scheme.",
        "positive": "Quantum Hall fractions in ultracold atomic vapors: Atomic vapors can be prepared and manipulated at very low densities and\ntemperatures. When they are rotating, they can reach a quantum Hall regime in\nwhich there should be manifestations of the fractional quantum Hall effect. We\ndiscuss the appearance of the principal sequence of fractions nu =p/(p+- 1) for\nbosonic atoms. The termination point of this series is the paired Moore-Read\nPfaffian state. Exotic states fill the gap between the paired state and the\nvortex lattice expected at high filling of the lowest Landau level. In\nfermionic vapors, the p-wave scattering typical of ultralow energy collisions\nleads to the hard-core model when restricted to the lowest Landau level."
    },
    {
        "anchor": "Controlling the Characteristics of Nanomechanical Resonators: The dynamics of nanomechanical resonators driven by both low- and\nhigh-frequency signals is studied. Considering, as an example, resonators made\nof a doubly-clamped beam with magnetomotive driving, it is shown that\nthree-frequency resonances arise due to the interaction of the above\nfrequencies. Properties and characteristics of these resonances are determined\nanalytically for linear and nonlinear modes of the resonator excitation. It is\nshown that in opposite to the conventional two-frequency resonance, the central\nfrequency of these resonances, their linear dynamic range, and the critical\nvalue for the bistability onset are easily controlled by changing the frequency\nand the amplitude of the low-frequency driving current. The obtained results\ncan be used when developing NMRs for sensors, filters, memory elements, and\nother applications.",
        "positive": "Transport signatures of quasiparticle poisoning in a Majorana island: We investigate effects of quasiparticle poisoning in a Majorana island with\nstrong tunnel coupling to normal-metal leads. In addition to the main Coulomb\nblockade diamonds, \"shadow\" diamonds appear, shifted by 1e in gate voltage,\nconsistent with transport through an excited (poisoned) state of the island.\nComparison to a simple model yields an estimate of parity lifetime for the\nstrongly coupled island (~ 1 {\\mu}s) and sets a bound for a weakly coupled\nisland (> 10 {\\mu}s). Fluctuations in the gate-voltage spacing of Coulomb peaks\nat high field, reflecting Majorana hybridization, are enhanced by the reduced\nlever arm at strong coupling. In energy units, fluctuations are consistent with\nprevious measurements."
    },
    {
        "anchor": "Photoabsorption spectra and the X-ray edge problem in graphene: We study the photoabsorption cross section and Fermi-edge singularities (FES)\nin graphene. For fillings below one half, we find, besides the expected FES in\nform of a peaked edge at the threshold (Fermi) energy, a second singularity to\narise at excitation energies that correspond to the Dirac point in the density\nof states. We can explain this behaviour by comparing our results with the\nphotoabsorption cross section of a metal with a small central band gap where we\nfind a very similar signature. The existence of the second singularity might\nprove useful for an experimental determination of the Dirac point. We also\ndemonstrate that the photoabsorption signal is enhanced by the zigzag edge\nstates due to their metallic-like character. Since the presence of the edge\nstates indicates a topological defect at the boundary, our study gives an\nexample for a Fermi-edge singularity in a system with a topologically\nnontrivial electronic spectrum.",
        "positive": "Cyclotron motion and magnetic focusing in semiconductor quantum wells\n  with spin-orbit coupling: We investigate the ballistic motion of electrons in III-V semiconductor\nquantum wells with Rashba spin-orbit coupling in a perpendicular magnetic\nfield. Taking into account the full quantum dynamics of the problem, we explore\nthe modifications of classical cyclotron orbits due to spin-orbit interaction.\nAs a result, for electron energies comparable with the cyclotron energy the\ndynamics are particularly rich and not adequately described by semiclassical\napproximations. Our study is complementary to previous semiclassical approaches\nconcentrating on the regime of weaker fields."
    },
    {
        "anchor": "Topological Boundary Modes in Isostatic Lattices: Frames, or lattices consisting of mass points connected by rigid bonds or\ncentral force springs, are important model constructs that have applications in\nsuch diverse fields as structural engineering, architecture, and materials\nscience. The difference between the number of bonds and the number of degrees\nof freedom of these lattices determines the number of their zero-frequency\n\"floppy modes\". When these are balanced, the system is on the verge of\nmechanical instability and is termed isostatic. It has recently been shown that\ncertain extended isostatic lattices exhibit floppy modes localized at their\nboundary. These boundary modes are insensitive to local perturbations, and\nappear to have a topological origin, reminiscent of the protected electronic\nboundary modes that occur in the quantum Hall effect and in topological\ninsulators. In this paper we establish the connection between the topological\nmechanical modes and the topological band theory of electronic systems, and we\npredict the existence of new topological bulk mechanical phases with distinct\nboundary modes. We introduce model systems in one and two dimensions that\nexemplify this phenomenon.",
        "positive": "Statistical theory of shot noise in quasi-1D Field Effect Transistors in\n  the presence of electron-electron interaction: We present an expression for the shot noise power spectral density in\nquasi-one dimensional conductors electrostatically controlled by a gate\nelectrode, that includes the effects of Coulomb interaction and of Pauli\nexclusion among charge carriers. In this sense, our expression extends the well\nknown Landauer-Buttiker noise formula to include the effect of Coulomb\ninteraction through induced fluctuations in the device potential. Our approach\nis based on the introduction of statistical properties of the scattering matrix\nand on a second-quantization many-body description. From a quantitative point\nof view, statistical properties are obtained by means of Monte Carlo\nsimulations on a ensemble of different configurations of injected states,\nrequiring the solution of the Poisson-Schrodinger equation on a\nthree-dimensional grid, with the non-equilibrium Green functions formalism. In\na series of example, we show that failure to consider the effects of Coulomb\ninteraction on noise leads to a gross overestimation of the noise spectrum of\nquasi-one dimensional devices."
    },
    {
        "anchor": "An anomalous band inversion protected by symmetry in a topological\n  insulator of the Kane-Mele model: Depositing Au on a graphene derivate, which involves substituting four C\natoms with three N atoms in a $3\\times 3$ cell graphene, we realized a\ntopological insulator of the Kane-Mele model with a gap of 50~meV surrounding\nthe Dirac point of graphene. In this material, we observed an anomalous band\ninversion (BI) protected by the symmetry with character $e$ of group C$_{\\rm\n3V}$. The symmetry constrains two $e$ bands with mirror-symmetry combination\n(MSC) and mirror-antisymmetry combination (MAC) of Au and N orbitals degenerate\nat $\\Gamma$, whereas the interaction of $\\pi^*$ of graphene on the $e$-MAC band\ntends to lift this degenerate, resulting in that the $\\pi^*$ and $e$-MAC band\nexchange their orbital components near $\\Gamma$, causing thus a discontinued\nBI.",
        "positive": "Probing two driven double quantum dots strongly coupled to a cavity: We experimentally and theoretically study a driven hybrid circuit quantum\nelectrodynamics (cQED) system beyond the dispersive coupling regime. Treating\nthe cavity as part of the driven system, we develop a theory applicable to such\nstrongly coupled and to multi-qubit systems. The fringes measured for a single\ndriven double quantum dot (DQD)-cavity setting and the enlarged splittings of\nthe hybrid Floquet states in the presence of a second DQD are well reproduced\nwith our model. This opens a path to study Floquet states of multi-qubit\nsystems with arbitrarily strong coupling and reveals a new perspective for\nunderstanding strongly driven hybrid systems."
    },
    {
        "anchor": "Doped Biomolecules in miniaturized electric junctions: Control over molecular scale electrical properties within nano junctions is\ndemonstrated, utilizing site-directed C60 targeting into protein macromolecules\nas a doping means. The protein molecules, self-assembled in a miniaturized\ntransistor device, yield robust and reproducible operation. Their device signal\nis dominated by an active center that inverts affinity upon guest incorporation\nand thus controls the properties of the entire macromolecule. We show how the\nleading routs of electron transport can be drawn, spatially and energetically,\non the molecular level and, in particular, how the dopant effect is dictated by\nits 'strategic' binding site. Our findings propose the extension of\nmicroelectronic methodologies to the nanometer scale and further present a\npromising platform for ex-situ studies of biochemical processes.",
        "positive": "Spontaneous emission in dispersive media without point-dipole\n  approximation: We study a two-level quantum system embedded in a dispersive environment and\ncoupled with the electromagnetic field. We expand the theory of light-matter\ninteractions to include the spatial extension of the system, taken into account\nthrough its wavefunctions. This is a development beyond the point-dipole\napproximation. This ingredient enables us to overcome the divergence problem\nrelated to the Green tensor propagator. Hence, we can reformulate the\nexpressions for the spontaneous emission rate and the Lamb shift. In\nparticular, the inclusion of the spatial structure of the atomic system\nclarifies the role of the asymmetry of atomic states with respect to spatial\ninversion in these quantities."
    },
    {
        "anchor": "Observation of Valley Zeeman and Quantum Hall Effects at Q Valley of\n  Few-Layer Transition Metal Disulfides: In few-layer (FL) transition metal dichalcogenides (TMDC), the conduction\nbands along the Gamma-K directions shift downward energetically in the presence\nof interlayer interactions, forming six Q valleys related by three-fold\nrotational symmetry and time reversal symmetry. In even-layers the extra\ninversion symmetry requires all states to be Kramers degenerate, whereas in\nodd-layers the intrinsic inversion asymmetry dictates the Q valleys to be\nspin-valley coupled. In this Letter, we report the transport characterization\nof prominent Shubnikov-de Hass (SdH) oscillations for the Q valley electrons in\nFL transition metal disulfide (TMDs), as well as the first quantum Hall effect\n(QHE) in TMDCs. Our devices exhibit ultrahigh field-effect mobilities (~16,000\ncm2V-1s-1 for FL WS2 and ~10,500 cm2V-1s-1 for FL MoS2) at cryogenic\ntemperatures. Universally in the SdH oscillations, we observe a valley Zeeman\neffect in all odd-layer TMD devices and a spin Zeeman effect in all even-layer\nTMD devices.",
        "positive": "Dependence of Carbon Nanotube Field Effect Transistors Performance on\n  Doping Level of Channel at Different Diameters: On/off current ratio: Choosing a suitable doping level of channel relevant to channel diameter is\nconsidered for determining the carbon nanotube field effect transistors'\nperformance which seem to be the best substitute of current transistor\ntechnology. For low diameter values of channel the ratio of on/off current\ndeclines by increasing the doping level. But for higher diameter values there\nis an optimum point of doping level in obtaining the highest on/off current\nratio. For further verification, the variations of performance are justified by\nelectron distribution function's changes on energy band diagram of these\ndevices. The results are compared at two different gate fields."
    },
    {
        "anchor": "Fractional Quantum Hall Effect at $\u03bd=1/2$ in Hole Systems Confined to\n  GaAs Quantum Wells: We observe fractional quantum Hall effect (FQHE) at the even-denominator\nLandau level filling factor $\\nu=1/2$ in two-dimensional hole systems confined\nto GaAs quantum wells of width 30 to 50 nm and having bilayer-like charge\ndistributions. The $\\nu=1/2$ FQHE is stable when the charge distribution is\nsymmetric and only in a range of intermediate densities, qualitatively similar\nto what is seen in two-dimensional electron systems confined to approximately\ntwice wider GaAs quantum wells. Despite the complexity of the hole Landau level\nstructure, originating from the coexistence and mixing of the heavy- and\nlight-hole states, we find the hole $\\nu=1/2$ FQHE to be consistent with a\ntwo-component, Halperin-Laughlin ($\\Psi_{331}$) state.",
        "positive": "Near-field thermodynamics: Useful work, efficiency, and energy\n  harvesting: We show that the maximum work that can be obtained from the thermal radiation\nemitted between two planar sources in the near-field regime is much larger than\nthat corresponding to the blackbody limit. This quantity as well as an upper\nbound for the efficiency of the process are computed from the formulation of\nthermodynamics in the near-field regime. The case when the difference of\ntemperatures of the hot source and the environment is small, relevant for\nenergy harvesting, is studied in detail. We also show that thermal radiation\nenergy conversion can be more efficient in the near-field regime. These results\nopen new possibilities for the design of energy converters that can be used to\nharvest energy from sources of moderate temperature at the nanoscale."
    },
    {
        "anchor": "A Microscopic Model of Edge States of Fractional Quantum Hall Liquid:\n  From Composite Fermions to Calogero-Sutherland Model: Based on the composite fermion approach, we derive a microscopic theory\ndescribing the low-lying edge excitations in the fractional quantum Hall liquid\nwith $\\nu=\\frac{\\nu^*}{\\tilde\\phi\\nu^*+1}$. For $\\nu^*>0$, it is found that the\ncomposite fermion model reduces to an SU$(\\nu^*)$ Calogero-Sutherland model in\nthe one-dimensional limit, whereas it is not exact soluble for $\\nu^*<0$.\nHowever, the ground states in both cases can be found and the low-lying\nexcitations can be shown the chiral Luttinger liquid behaviors since a gap\nexists between the right- and left-moving sectors in each branch of the\nazimuthal excitations.",
        "positive": "Topological Dirac states beyond $\u03c0$ orbitals for silicene on SiC(0001)\n  surface: The discovery of intriguing properties related to the Dirac states in\ngraphene has spurred huge interest in exploring its two-dimensional group-IV\ncounterparts, such as silicene, germanene, and stanene. However, these\nmaterials have to be obtained via synthesizing on substrates with strong\ninterfacial interactions, which usually destroy their intrinsic\n$\\pi$($p_z$)-orbital Dirac states. Here we report a theoretical study on the\nexistence of Dirac states arising from the $p_{x,y}$ orbitals instead of $p_z$\norbitals in silicene on 4H-SiC(0001), which survive in spite of the strong\ninterfacial interactions. We also show that the exchange field together with\nthe spin-orbital coupling give rise to a detectable band gap of 1.3 meV. Berry\ncurvature calculations demonstrate the nontrivial topological nature of such\nDirac states with a Chern number $C = 2$, presenting the potential of realizing\nquantum anomalous Hall effect for silicene on SiC(0001). Finally, we construct\na minimal effective model to capture the low-energy physics of this system.\nThis finding is expected to be also applicable to germanene and stanene, and\nimply great application potentials in nanoelectronics."
    },
    {
        "anchor": "Electronic properties of quantum dots formed by magnetic double barriers\n  in quantum wires: The transport through a quantum wire exposed to two magnetic spikes in series\nis modeled. We demonstrate that quantum dots can be formed this way which\ncouple to the leads via magnetic barriers. Conceptually, all quantum dot states\nare accessible by transport experiments. The simulations show Breit-Wigner\nresonances in the closed regime, while Fano resonances appear as soon as one\nopen transmission channel is present. The system allows to tune the dot's\nconfinement potential from sub-parabolic to superparabolic by experimentally\naccessible parameters.",
        "positive": "Nonequilibrium reservoir engineering of a biased coherent conductor for\n  hybrid energy transport in nanojunctions: We show that a current-carrying coherent electron conductor can be treated as\neffective bosonic energy reservoir involving different types of electron-hole\npair excitation. For weak electron-boson coupling, hybrid energy transport\nbetween nonequilibrium electrons and bosons can be described by a Landauer-like\nformula. This allows for unified account of a variety of heat transport\nproblems in hybrid electron-boson systems. As applications, we study the\nnon-reciprocal heat transport between electrons and bosons, thermoelectric\ncurrent from a cold-spot and electronic cooling of the bosons. Our unified\nframework provides an intuitive way of understanding hybrid energy transport\nbetween electrons and bosons. It opens the way of nonequilibrium reservoir\nengineering for efficient energy control between different quasi-particles in\nthe nanoscale."
    },
    {
        "anchor": "High quality-factor mechanical resonators based on WSe2 monolayers: Suspended monolayer transition metal-dichalcogenides (TMD) are membranes that\ncombine ultra-low mass and exceptional optical properties, making them\nintriguing materials for opto-mechanical applications. However, the low\nmeasured quality factor of TMD resonators has been a roadblock so far. Here, we\nreport an ultrasensitive optical readout of monolayer TMD resonators that\nallows us to reveal their mechanical properties at cryogenic temperatures. We\nfind that the quality factor of monolayer WSe2 resonators greatly increases\nbelow room temperature, reaching values as high as 1.6E^4 at liquid nitrogen\ntemperature and 4.7E^4 at liquid helium temperature. This surpasses the quality\nfactor of monolayer graphene resonators with similar surface areas. Upon\ncooling the resonator, the resonant frequency increases significantly due to\nthe thermal contraction of the WSe2 lattice. These measurements allow us to\nexperimentally study the thermal expansion coefficient of WSe2 monolayers for\nthe first time. High Q-factors are also found in resonators based on MoS2 and\nMoSe2 monolayers. The high quality-factor found in this work opens new\npossibilities for coupling mechanical vibrational states to two-dimensional\nexcitons, valley pseudospins, and single quantum emitters, and for quantum\nopto-mechanical experiments based on the Casimir interaction.",
        "positive": "Stretching-induced conductance variations as fingerprints of contact\n  configurations in single-molecule junctions: Molecule-electrode contact atomic structures are a critical factor that\ncharacterizes molecular devices, but their precise understanding and control\nstill remain elusive. Based on combined first-principles calculations and\nsingle-molecule break junction experiments, we herein establish that the\nconductance of alkanedithiolate junctions can both increase and decrease with\nmechanical stretching and the specific trend is determined by the S-Au linkage\ncoordination number (CN) or the molecule-electrode contact atomic structure.\nSpecifically, we find that the mechanical pulling results in the conductance\nincrease for the junctions based on S-Au CN two and CN three contacts, while\nthe conductance is minimally affected by stretching for junctions with the CN\none contact and decreases upon the formation of Au monoatomic chains. Detailed\nanalysis unravels the mechanisms involving the competition between the\nstretching-induced upshift of the highest occupied molecular orbital-related\nstates toward the Fermi level of electrodes and the deterioration of\nmolecule-electrode electronic couplings in different contact CN cases.\nMoreover, we experimentally find a higher chance to observe the conductance\nenhancement mode under a faster elongation speed, which is explained by ab\ninitio molecular dynamics simulations that reveal an important role of thermal\nfluctuations in aiding deformations of contacts into low-coordination\nconfigurations that include monoatomic Au chains. Pointing out the\ninsufficiency in previous notions of associating peak values in conductance\nhistograms with specific contact atomic structures, this work resolves the\ncontroversy on the origins of ubiquitous multiple conductance peaks in\nS-Au-based single-molecule junctions."
    },
    {
        "anchor": "Quantum emission assisted by energy landscape modification in\n  pentacene-decorated carbon nanotubes: Photoluminescent carbon nanotubes are expected to become versatile\nroom-temperature single-photon sources that have applications in quantum\ninformation processing. Quantum emission from carbon nanotubes is often induced\nby localization of excitons or exciton-exciton annihilation. Here, we modify\nthe local energy landscape of excitons by decorating nanoscale pentacene\nparticles onto air-suspended single-walled carbon nanotubes. Directional\nexciton diffusion from the undecorated region to the decorated site is\ndemonstrated, suggesting exciton trapping induced by local dielectric screening\nfrom pentacene particles. Photoluminescence and photon correlation measurements\non a representative carbon nanotube reveal enhanced exciton-exciton\nannihilation and single-photon emission at room temperature. Pentacene\nparticles are shown to promote strong photon antibunching at the decorated\nsite, indicating that noncovalent functionalization using molecules can be an\neffective approach for energy landscape modification and quantum emission in\ncarbon nanotubes.",
        "positive": "Cryogenic Control Architecture for Large-Scale Quantum Computing: Solid-state qubits have recently advanced to the level that enables them,\nin-principle, to be scaled-up into fault-tolerant quantum computers. As these\nphysical qubits continue to advance, meeting the challenge of realising a\nquantum machine will also require the engineering of new classical hardware and\ncontrol architectures with complexity far beyond the systems used in today's\nfew-qubit experiments. Here, we report a micro-architecture for controlling and\nreading out qubits during the execution of a quantum algorithm such as an error\ncorrecting code. We demonstrate the basic principles of this architecture in a\nconfiguration that distributes components of the control system across\ndifferent temperature stages of a dilution refrigerator, as determined by the\navailable cooling power. The combined setup includes a cryogenic\nfield-programmable gate array (FPGA) controlling a switching matrix at 20\nmillikelvin which, in turn, manipulates a semiconductor qubit."
    },
    {
        "anchor": "Band gaps in incommensurable graphene on hexagonal boron nitride: Devising ways of opening a band gap in graphene to make charge-carrier masses\nfinite is essential for many applications. Recent experiments with graphene on\nhexagonal boron nitride (h-BN) offer tantalizing hints that the weak\ninteraction with the substrate is sufficient to open a gap, in contradiction of\nearlier findings. Using many-body perturbation theory, we find that the small\nobserved gap is what remains after a much larger underlying quasiparticle gap\nis suppressed by incommensurability. The sensitivity of this suppression to a\nsmall modulation of the distance separating graphene from the substrate\nsuggests ways of exposing the larger underlying gap.",
        "positive": "Is the largest aqueous gold cluster a superatom complex? Electronic\n  structure & optical response of the structurally determined Au146(pMBA)57: The new water-soluble gold cluster Au146(pMBA)57, the structure of which has\nbeen recently determined at sub-atomic resolution by Vergara et al. [1], is the\nlargest aqueous gold cluster ever structurally determined and likewise the\nsmallest cluster with a stacking fault. The core presents a twinned truncated\noctahedron, while additional peripheral gold atoms follow a C2 rotational\nsymmetry. According to the usual counting rules of the superatom complex (SAC)\nmodel, the compound attains a number of 92 SAC electrons if the overall net\ncharge is 3- (three additional electrons). As this is the number of electrons\nrequired for a major shell closing, the question arises if Au146(pMBA)57 should\nbe regarded as a superatom complex. Starting from the experimental coordinates\nwe have analyzed the structure using density-functional theory. The optimized\n(relaxed) structure retains all the connectivity of the experimental\ncoordinates, while removing much of its irregularities in interatomic\ndistances, thereby enhancing the C2-symmetry feature. Analyzing the\nangular-momentum projected states, we show that, despite a small gap, the\nelectronic structure does not exhibit SAC model character. In addition, optical\nabsorption spectra are found to be relatively smooth compared to the example of\nthe Au144(SR)60 cluster. The Au146(SR)57 cluster does not derive its stability\nfrom SAC character; it cannot be considered a superatom complex."
    },
    {
        "anchor": "Universality of Abelian and non-Abelian Wannier functions in one\n  dimension: Within a Dirac model in $1+1$ dimensions, a prototypical model to describe\nlow-energy physics for a wide class of lattice models, we propose a\nfield-theoretical version for the representation of Wannier functions, the\nZak-Berry connection, and the geometric tensor. In two natural Abelian gauges\nwe present universal scaling of the Dirac Wannier functions in terms of four\nfundamental scaling functions that depend only on the phase $\\gamma$ of the gap\nparameter and the charge correlation length $\\xi$ in an insulator. The two\ngauges allow for a universal low-energy formulation of the surface charge and\nsurface fluctuation theorem, relating the boundary charge and its fluctuations\nto bulk properties. Our analysis describes the universal aspects of Wannier\nfunctions for the wide class of one-dimensional generalized\nAubry-Andr\\'e-Harper lattice models. In the low-energy regime of small gaps we\ndemonstrate universal scaling of all lattice Wannier functions and their\nmoments in the corresponding Abelian gauges. We also discuss non-Abelian\nlattice gauges and find that lattice Wannier functions of maximal localization\nshow universal scaling and are uniquely related to the Dirac Wannier function\nof the lower band. Our results present evidence that universal aspects of\nWannier functions and of the boundary charge are uniquely related and can be\nelegantly described within universal low-energy theories.",
        "positive": "Mechanics of freely-suspended ultrathin layered materials: The study of atomically thin two-dimensional materials is a young and rapidly\ngrowing field. In the past years, a great advance in the study of the\nremarkable electrical and optical properties of 2D materials fabricated by\nexfoliation of bulk layered materials has been achieved. Due to the\nextraordinary mechanical properties of these atomically thin materials, they\nalso hold a great promise for future applications such as flexible electronics.\nFor example, this family of materials can sustain very large deformations\nwithout breaking. Due to the combination of small dimensions, high Young's\nmodulus and high crystallinity of 2D materials, they have attracted the\nattention of the field of nanomechanical systems as high frequency and high\nquality factor resonators. In this article, we review experiments on static and\ndynamic response of 2D materials. We provide an overview and comparison of the\nmechanics of different materials, and highlight the unique properties of these\nthin crystalline layers. We conclude with an outlook of the mechanics of 2D\nmaterials and future research directions such as the coupling of the mechanical\ndeformation to their electronic structure."
    },
    {
        "anchor": "Probing of valley polarization in graphene via optical second-harmonic\n  generation: Valley polarization in graphene breaks inversion symmetry and therefore leads\nto second-harmonic generation. We present a complete theory of this effect\nwithin a single-particle approximation. It is shown that this may be a\nsensitive tool to measure the valley polarization created, e.g., by polarized\nlight and, thus, can be used for a development of ultrafast valleytronics in\ngraphene.",
        "positive": "Multi-Terminal Superconducting Phase Qubit: Mesoscopic multi-terminal Josephson junctions are novel devices that provide\nweak coupling between several bulk superconductors through a common normal\nlayer. Because of the nonlocal coupling of the superconducting banks, a current\nflow between two of the terminals can induce a phase difference and/or current\nflow in the other terminals. This \"phase dragging\" effect is used in designing\na new type of superconducting phase qubit, the basic element of a quantum\ncomputer. Time-reversal symmetry breaking can be achieved by inserting a\npi-phase shifter into the flux loop. Logical operations are done by applying\ncurrents. This removes the necessity for local external magnetic fields to\nachieve bistability or controllable operations."
    },
    {
        "anchor": "Acoustic Higher-Order Weyl Semimetal with Bound Hinge States in the\n  Continuum: Higher-order topological phases have raised widespread interest in recent\nyears with the occurrence of the topological boundary states of dimension two\nor more less than that of the system bulk. The higher-order topological states\nhave been verified in gapped phases, in a wide variety of systems, such as\nphotonic and acoustic systems, and recently also observed in gapless semimetal\nphase, such as Weyl and Dirac phases, in systems alike. The higher-order\ntopology is signaled by the hinge states emerging in the common bandgaps of the\nbulk states and the surface states. In this Letter, we report our first\nprediction and observation of a new type of hinge states, the bound hinge\nstates in the continuum (BHICs) bulk band, in a higher-order Weyl semimetal\nimplemented in phononic crystal. In contrast to the hinge state in gap, which\nis characterized by the bulk polarization, the BHIC is identified by the\nnontrivial surface polarization. The finding of the topological BHICs broadens\nour insight to the topological states, and may stimulate similar researches in\nother systems such as electronic, photonic, and cold atoms systems. Our work\nmay pave the way toward high-Q acoustic devices in application.",
        "positive": "Piezoelectric Polar Nano Regions and Relaxation-Coupled Resonances in\n  Relaxor Ferroelectrics: \\indent It is a generally accepted fact that the unique dielectric properties\nof relaxor ferroelectrics are related to the formation of polar nanoregion\n(PNRs). Less well recognized is the corollary that, because they are polar and\ntherefore lack inversion symmetry, PNRs are also piezoelectric at the nanoscale\nand can therefore behave as nanoresonators. Using the particular relaxor\nferroelectric K$_{\\tt1-x}$Li$_{\\tt x}$TaO$_{\\tt 3}$ (KLT), we show that, when\nelectrically excited into oscillation, these piezoelectric nanoresonators can\ndrive macroscopic electro-mechanical resonances. Unexpectedly however, pairs of\ncoupled resonances are observed, with one of the two exhibiting a\ncharacteristic Fano-like lineshape. The complex resonance spectra can be\ndescribed equally well by two alternative but complementary models both\ninvolving two resonances coupled through a relaxation: a purely classical one\nbased on two coupled damped harmonic oscillators and a semi-classical based on\ntwo discrete excitations coupled to each other through a continuum. Together,\nthey provide complementary perspectives on the underlying physics of the\nsystem. Both reproduce the rapid evolution of the resonance spectrum across\nthree wide temperature ranges, including a phase transition range. In the high\ntemperature range, the coupling between modes is due to the collective $\\pi$\nrelaxation of the lithium ions within PNRs and in the phase transition range to\n\"heterophase relaxation\" of the surrounding lattice between its high\ntemperature cubic and low temperature tetragonal phases. The coupling is\nsuppressed in the intermediate range of the collective $\\pi/2$ relaxation of\nthe lithium ions. Incidentally, the measured dielectric spectra are shown to\nbear a surprising but justifiable resemblance to the optical spectra of certain\natomic vapors that exhibit electromagnetically induced transparency."
    },
    {
        "anchor": "An integrated capacitance bridge for high-resolution, wide temperature\n  range quantum capacitance measurements: We have developed a highly-sensitive integrated capacitance bridge for\nquantum capacitance measurements. Our bridge, based on a GaAs HEMT amplifier,\ndelivers attofarad (aF) resolution using a small AC excitation at or below kT\nover a broad temperature range (4K-300K). We have achieved a resolution at room\ntemperature of 10aF per root Hz for a 10mV AC excitation at 17.5 kHz, with\nimproved resolution at cryogenic temperatures, for the same excitation\namplitude. We demonstrate the performance of our capacitance bridge by\nmeasuring the quantum capacitance of top-gated graphene devices and comparing\nagainst results obtained with the highest resolution commercially-available\ncapacitance measurement bridge. Under identical test conditions, our bridge\nexceeds the resolution of the commercial tool by up to several orders of\nmagnitude.",
        "positive": "Skyrmion Formation Induced by Antiferromagnetic-enhanced Interfacial\n  Dzyaloshinskii Moriya Interaction: Ne\\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction\n(DMI). Recent studies have explored using ferromagnet to host Ne\\'el skyrmions\nfor device applications. However, challenges remain to reduce the size of\nskyrmion to near 10 nm. Amorphous rare-earth-transitional-metal ferrimagnets\nare attractive alternative materials to obtain ultrasmall skyrmions at room\ntemperature. Their intrinsic perpendicular magnetic anisotropy and tunable\nmagnetization provides a favorable environment for skyrmion stability. In this\nwork, we employ atomistic stochastic Landau-Liftshitz-Gilbert (LLG) algorithm\nto investigate skyrmions in GdFe within the interfacial DMI model. Despite the\nrapid decay of DMI away from the interface, small skyrmions of near 10 nm are\nfound in thick ~ 5 nm amorphous GdFe film at 300K. We have also considered\nthree scenarios for the sign of DMI between Gd-Fe pair. It is revealed that\nantiferromagnetic coupling in the ferrimagnet plays an important role in\nenhancing the effect of interfacial DMI and to stabilize skyrmion. These\nresults show that ferrimagnets and antiferromagnets with intrinsic\nantiferromagnetic couplings are appealing materials to host small skyrmions at\nroom temperature, which is crucial to improve density and energy efficiency in\nskyrmion based devices."
    },
    {
        "anchor": "Magnetic nanotubes: A new material platform to realize robust\n  spin-Seebeck effect and perfect thermal spin-filtering effect: To construct reliable material platforms and to uncover new rules to realize\nspin-Seebeck effect (SSE) and thermal spin-filtering effect (SFE) are core\ntopics in spin caloritronics. Here we design several single-layer\nboron-nitrogen nanotubes (BNNTs) with n boron (nitrogen) atoms substituted by\ncarbons in every unit cell. We find that for n = 1, the magnetic BNNTs generate\na good SSE with nearly symmetric spin-up and spin-down currents; while as the\ncarbon dopant concentration increases (c.f. n $\\geq$ 2), a high rotational\nsymmetry of the carbons contributes to generate the SSE with more symmetric\nthermal spin-up and spin-down currents, otherwise towards the thermal SFE.\nMoreover, some metallic BNNTs can generate the SSE or the SFE with finite\nthreshold temperatures, due to the compensation effect around the Fermi level.\nMore importantly, we find that the compression strain engineering is an\neffective route to improve these effects and to realize the transition between\nthem. These theoretical results about the SSE in nanotubes enrich the spin\ncaloritronics, and put forwards new material candidates to realize the SSE and\nother inspiring thermospin phenomena",
        "positive": "Ballistic transport is dissipative: the why and how: In the ballistic limit, the Landauer conductance steps of a mesoscopic\nquantum wire have been explained by coherent and dissipationless transmission\nof individual electrons across a one-dimensional barrier. This leaves untouched\nthe central issue of conduction: a quantum wire, albeit ballistic, has finite\nresistance and so must dissipate energy. Exactly HOW does the quantum wire shed\nits excess electrical energy? We show that the answer is provided, uniquely, by\nmany-body quantum kinetics. Not only does this inevitably lead to universal\nquantization of the conductance, in spite of dissipation; it fully resolves a\nbaffling experimental result in quantum-point-contact noise. The underlying\nphysics rests crucially upon the action of the conservation laws in these open\nmetallic systems."
    },
    {
        "anchor": "Nonequilibrium spin current through interacting quantum dots: We develop a theory for charge and spin current between two canted magnetic\nleads flowing through a quantum dot with an arbitrary local interaction. For a\nnoncollinear magnetic configuration, we calculate equilibrium and\nnonequilibrium current biased by voltage or temperature difference or pumped by\nmagnetic dynamics. We are able to explicitly separate the equilibrium and\nnonequilibrium contributions to the current, both of which can be written in\nterms of the full retarded Green's function on the dot. Taking the specific\nexample of a single-level quantum dot with a large on-site Coulomb interaction,\nwe calculate the total spin current near the Kondo regime, which we find to be\ngenerally enhanced in magnitude as compared to the noninteracting case.",
        "positive": "Triple Point Topological Metals: Topologically protected fermionic quasiparticles appear in metals, where band\ndegeneracies occur at the Fermi level, dictated by the band structure topology.\nWhile in some metals these quasiparticles are direct analogues of elementary\nfermionic particles of the relativistic quantum field theory, other metals can\nhave symmetries that give rise to quasiparticles, fundamentally different from\nthose known in high-energy physics. Here we report on a new type of topological\nquasiparticles -- triple point fermions -- realized in metals with symmorphic\ncrystal structure, which host crossings of three bands in the vicinity of the\nFermi level protected by point group symmetries. We find two topologically\ndifferent types of triple point fermions, both distinct from any other\ntopological quasiparticles reported to date. We provide examples of existing\nmaterials that host triple point fermions of both types, and discuss a variety\nof physical phenomena associated with these quasiparticles, such as the\noccurrence of topological surface Fermi arcs, transport anomalies and\ntopological Lifshitz transitions."
    },
    {
        "anchor": "Spin polarization and effective mass: a numerical study in disordered\n  two dimensional systems: We numerically study the magnetization of small metallic clusters. The\nmagnetic susceptibility is enhanced for lower electronic densities due to the\nstronger influence of electron-electron interactions. The magnetic\nsusceptibility enhancement stems mainly from an enhancement of the mass for\ncommensurate fillings, while for non-commensurate fillings its a result of an\nenhancement of the Land\\'e $g$ factor. The relevance to recent experimental\nmeasurements is discussed.",
        "positive": "Monolayer Mg$_{2}$C: Negative Poisson's ratio and unconventional 2D\n  emergent fermions: Novel two-dimensional (2D) emergent fermions and negative Poisson's ratio in\n2D materials are fascinating subjects of research. Here, based on\nfirst-principles calculations and theoretical analysis, we predict that the\nhexacoordinated Mg$_{2}$C monolayer hosts both exotic properties. We analyze\nits phonon spectrum, reveal the Raman active modes, and show that it has small\nin-plane stiffness constants. Particularly, under the tensile strain in the\nzigzag direction, the Mg$_{2}$C monolayer shows an intrinsic negative Poisson's\nratio $\\sim -0.023$, stemming from its unique puckered hinge structure. The\nmaterial is metallic at its equilibrium state. A moderate biaxial strain can\ninduce a metal-semimetal-semiconductor phase transition, during which several\nnovel types of 2D fermions emerge, including the anisotropic Dirac fermions\naround 12 tilted Dirac points in the metallic phase, the $2$D double Weyl\nfermions in the semimetal phase where the conduction and valence bands touch\nquadratically at a single Fermi point, and the 2D pseudospin-1 fermions at the\ncritical point of the semimetal-semiconductor phase transition where three\nbands cross at a single point on the Fermi level. In addition, uniaxial strains\nalong the high-symmetry directions break the three-fold rotational symmetry and\nreduce the number of Dirac points. Interestingly, it also generates 2D type-II\nDirac points. We construct effective models to characterize the properties of\nthese novel fermions. Our result reveals Mg$_{2}$C monolayer as an intriguing\nplatform for the study of novel 2D fermions, and also suggests its great\npotential for nanoscale device applications."
    },
    {
        "anchor": "Berry curvature in monolayer MoS$_2$ with broken mirror symmetry: An ideal 1H phase monolayer MoS$_2$ has the mirror reflection symmetry but\nthis symmetry is broken in common experimental situations, where the monolayer\nis placed on a substrate. By using the k$\\cdot$p perturbation theory, we\ninvestigate the effect of the mirror symmetry breaking on the Berry curvature\nof the material. We find that the symmetry breaking may modify the Berry\ncurvature considerably and the spin/valley Hall effect due to the modified\nBerry curvature is in qualitative agreement with a recent experimental result\n[Science $\\bf 344$, 1489 (2014)], which cannot be explained by previous\ntheories that ignore the mirror symmetry breaking.",
        "positive": "Impact of electrostatic crosstalk on spin qubits in dense CMOS quantum\n  dot arrays: Quantum processors based on integrated nanoscale silicon spin qubits are a\npromising platform for highly scalable quantum computation. Current CMOS spin\nqubit processors consist of dense gate arrays to define the quantum dots,\nmaking them susceptible to crosstalk from capacitive coupling between a dot and\nits neighbouring gates. Small but sizeable spin-orbit interactions can transfer\nthis electrostatic crosstalk to the spin g-factors, creating a dependence of\nthe Larmor frequency on the electric field created by gate electrodes\npositioned even tens of nanometers apart. By studying the Stark shift from tens\nof spin qubits measured in nine different CMOS devices, we developed a\ntheoretical frawework that explains how electric fields couple to the spin of\nthe electrons in increasingly complex arrays, including those electric\nfluctuations that limit qubit dephasing times $T_2^*$. The results will aid in\nthe design of robust strategies to scale CMOS quantum technology."
    },
    {
        "anchor": "Intrinsic localized modes in parametrically-driven arrays of nonlinear\n  resonators: We study intrinsic localized modes (ILMs), or solitons, in arrays of\nparametrically-driven nonlinear resonators with application to\nmicroelectromechanical and nanoelectromechanical systems (MEMS and NEMS). The\nanalysis is performed using an amplitude equation in the form of a nonlinear\nSchroedinger equation with a term corresponding to nonlinear damping (also\nknown as a forced complex Ginzburg-Landau equation), which is derived directly\nfrom the underlying equations of motion of the coupled resonators, using the\nmethod of multiple scales. We investigate the creation, stability, and\ninteraction of ILMs, show that they can form bound states, and that under\ncertain conditions one ILM can split into two. Our findings are confirmed by\nsimulations of the underlying equations of motion of the resonators, suggesting\npossible experimental tests of the theory.",
        "positive": "Tailored nano-antennas for directional Raman studies of individual\n  carbon nanotubes: We exploit the near field enhancement of nano-antennas to investigate the\nRaman spectra of otherwise not optically detectable carbon nanotubes (CNTs). We\ndemonstrate that a top-down fabrication approach is particularly promising when\napplied to CNTs, owing to the sharp dependence of the scattered intensity on\nthe angle between incident light polarization and CNT axis. In contrast to tip\nenhancement techniques, our method enables us to control the light polarization\nin the sample plane, locally amplifying and rotating the incident field and\nhence optimizing the Raman signal. Such promising features are confirmed by\nnumerical simulations presented here. The relative ease of fabrication and\nalignment makes this technique suitable for the realization of integrated\ndevices that combine scanning probe, optical, and transport characterization."
    },
    {
        "anchor": "Transport of Surface States in the Bulk Quantum Hall Effect: The two-dimensional surface of a coupled multilayer integer quantum Hall\nsystem consists of an anisotropic chiral metal. This unusual metal is\ncharacterized by ballistic motion transverse and diffusive motion parallel\n(\\hat{z}) to the magnetic field. Employing a network model, we calculate\nnumerically the phase coherent two-terminal z-axis conductance and its\nmesoscopic fluctuations. Quasi-1d localization effects are evident in the limit\nof many layers. We consider the role of inelastic de-phasing effects in\nmodifying the transport of the chiral surface sheath, discussing their\nimportance in the recent experiments of Druist et al.",
        "positive": "Quantum heat engines based on electronic Mach-Zehnder interferometers: We theoretically investigate the thermoelectric properties of heat engines\nbased on Mach-Zehnder interferometers. The energy dependence of the\ntransmission amplitudes in such setups arises from a difference in the\ninterferometer arm lengths. Any thermoelectric response is thus of purely\nquantum mechanical origin. In addition to an experimentally established\nthree-terminal setup, we also consider a two-terminal geometry as well as a\nfour-terminal setup consisting of two interferometers. We find that\nMach-Zehnder interferometers can be used as powerful and efficient heat engines\nwhich perform well under realistic conditions."
    },
    {
        "anchor": "The role of the C2 gas in the emergence of C60 from the condensing\n  carbon vapour: A model has been developed that illustrates the emergence of C60 from the\ncondensing carbon vapor. It is shown to depend upon the decreasing heats of\nformation for larger cages, exponentially increasing number of isomers for\nfullerenes that are larger than C60, large cages buckling induced by the\npentagon-related protrusions that initiate fragmentation, the structural\ninstability induces fragmentation that shrinks large cages and an evolving gas\nof C2 that is crucial to the whole process. The model describes a mechanism for\nthe provision and presence of plenty of C2 during the formation and\nfragmentation processes. The bottom-up formations of large cages followed by\nthe top-down cage shrinkage are shown to be stable, dynamical processes that\nlead to the C60 dominated fullerene ensemble.",
        "positive": "Preferred States of Open Electronic Systems: System-environment interaction may introduce dynamic destruction of quantum\ncoherence, resulting in a special representation named as pointer states. Here,\npointer states of an open electronic system are studied. The decoherence effect\nis taken into account through two different models which are B\\\"{u}ttiker's\nvirtual probe model and electron-phonon interaction in the polaron picture. The\npointer states of the system with different coupling strength are investigated.\nThe pointer states are identified by tracking the eigenstates of the density\nmatrix in real-time evolution. It is found that the pointer states can emerge\nfor arbitrary coupling strength. And the pointer states deform to the\neigenstates of the system in the strong coupling limit, which indicates the\nvanish of quantumness in the strong coupling limit."
    },
    {
        "anchor": "The microscopic picture of the integer quantum Hall regime: Computer modelling of the integer quantum Hall effect based on\nself-consistent Hartee-Fock calculations has now reached an astonishing level\nof maturity. Spatially-resolved studies of the electron density at near\nmacroscopic system sizes of up to $\\sim 1\\ \\mu m^2$ reveal self-organized\nclusters of locally fully filled and locally fully depleted Landau levels\ndepending on which spin polarization is favoured. The behaviour results, for\nstrong disorders, in an exchange-interaction induced $g$-factor enhancement\nand, ultimately, gives rise to narrow transport channels, including the\ncelebrated narrow edge channels. For weak disorder, we find that bubble and\nstripes phases emerge with characteristics that predict experimental results\nvery well. Hence the HF approach has become a convenient numerical basis to\n\\emph{quantitatively} study the quantum Hall effects, superseding previous more\nqualitative approaches.",
        "positive": "Tunable Lyapunov exponent in inverse magnetic billiards: The stability properties of the classical trajectories of charged particles\nare investigated in a two dimensional stadium-shaped inverse magnetic domain,\nwhere the magnetic field is zero inside the stadium domain and constant\noutside. In the case of infinite magnetic field the dynamics of the system is\nthe same as in the Bunimovich billiard, i.e., ergodic and mixing. However, for\nweaker magnetic fields the phase space becomes mixed and the chaotic part\ngradually shrinks. The numerical measurements of the Lyapunov exponent\n(performed with a novel method) and the integrable/chaotic phase space volume\nratio show that both quantities can be smoothly tuned by varying the external\nmagnetic field. A possible experimental realization of the arrangement is also\ndiscussed."
    },
    {
        "anchor": "How quickly can anyons be braided? Or: How I learned to stop worrying\n  about diabatic errors and love the anyon: Topological phases of matter are a potential platform for the storage and\nprocessing of quantum information with intrinsic error rates that decrease\nexponentially with inverse temperature and with the length scales of the\nsystem, such as the distance between quasiparticles. However, it is less\nwell-understood how error rates depend on the speed with which non-Abelian\nquasiparticles are braided. In general, diabatic corrections to the holonomy or\nBerry's matrix vanish at least inversely with the length of time for the braid,\nwith faster decay occurring as the time-dependence is made smoother. We show\nthat such corrections will not affect quantum information encoded in\ntopological degrees of freedom, unless they involve the creation of\ntopologically nontrivial quasiparticles. Moreover, we show how measurements\nthat detect unintentionally created quasiparticles can be used to control this\nsource of error.",
        "positive": "Observation of topological nodal-line fermionic phase in GdSbTe: Topological Dirac semimetals with accidental band touching between conduction\nand valence bands protected by time reversal and inversion symmetry are at the\nfrontier of modern condensed matter research. Theoretically one can get Weyl\nand/or nodal-line semimetals by breaking either one of them. Most of the\ndiscovered topological semimetals are nonmagnetic i.e respect time reversal\nsymmetry. Here we report the experimental observation of a topological\nnodal-line semi metallic state in GdSbTe using angle-resolved photoemission\nspectroscopy. Our systematic study reveals the detailed electronic structure of\nthe paramagnetic state of GdSbTe. We observe the presence of multiple Fermi\nsurface pockets including a diamond-shape, an elliptical shape, and small\ncircular pockets around the zone center and high symmetry M and X points of the\nBrillouin zone (BZ), respectively. Furthermore, we observe the presence of a\nDirac-like state at the X point of the BZ. Interestingly, our experimental data\nshows a robust Dirac like state both below and above the magnetic transition\ntemperature (T_N ~ 13 K). Having relatively higher transition temperature,\nGdSbTe provides an archetype platform to study the interaction between\nmagnetism and topological states of matter."
    },
    {
        "anchor": "Electron-hole pairing in topological insulator heterostructures in the\n  quantum Hall state: A thin film of a topological insulator (TI) on a dielectric substrate and a\nbulk TI - dielectric film - bulk TI structure are considered as natural\ndouble-well heterostructures suitable for realizing the counterflow\nsuperconductivity. The effect is connected with pairing of electrons and holes\nbelonging to different surfaces of TI and the transition of a gas of\nelectron-hole pairs into a superfluid state. The case of TI heterostructures\nsubjected to a strong perpendicular magnetic field is considered. It is shown\nthat such systems are characterized by two critical temperatures - a mean-field\ntemperature of pairing and a much smaller temperature of the superfluid\ntransition. The dependence of the critical temperatures on the magnetic field\nis computed. The advantages of TI based structures in comparison with GaAs\nheterostructures as well as graphene based heterostructures are discussed.",
        "positive": "High-order cumulants in the counting statistics of asymmetric quantum\n  dots: Measurements of single electron tunneling through a quantum dot using a\nquantum point contact as charge detector have been performed for very long time\ntraces with very large event counts. This large statistical basis is used for a\ndetailed examination of the counting statistics for varying symmetry of the\nquantum dot system. From the measured statistics we extract high order\ncumulants describing the distribution. Oscillations of the high order cumulants\nare observed when varying the symmetry. We compare this behavior to the\nobserved oscillation in time dependence and show that the variation of both\nsystem variables lead to the same kind of oscillating response."
    },
    {
        "anchor": "Second Harmonic Generation in h-BN and MoS$_2$ monolayers: the role of\n  electron-hole interaction: In this letter we show by means of first principle numerical simulations that\nelectron-hole interaction significantly contributes to the second-harmonic\ngeneration spectrum of h-BN or MoS$_2$ monolayers. Specifically, it doubles the\nsignal intensity at the excitonic resonances with respect to the contribution\nfrom independent electronic transitions. This result hints that the intensity\nof second-harmonic signal of those materials can be tuned by changing the\ndielectric screening, that controls the strength of the electron-hole\ninteraction.",
        "positive": "Optical detection of single electron transport dynamics: The unpredictability of a single quantum event lies at the very core of\nquantum mechanics. Physical information is therefore drawn from a statistical\nevaluation of many such processes. Nevertheless, recording each single quantum\nevent in a time trace the \"random telegraph signal\" is of great value, as it\nallows insight into the underlying physical system. Here, quantum dots have\nproven to be well suited systems, as they exhibit both single photon emission\nand single electron charge transport. While single photon emission is generally\nstudied on self-assembled quantum dots, single electron transport studies are\nfocused on gate-defined structures. We investigate, on a single self-assembled\nquantum dot, the single electron transport in the optical telegraph signal with\nhigh bandwidth and observe in the full counting statistics the interplay\nbetween charge and spin dynamics in a noninvasive way. In particular, we are\nable to identify the spin relaxation of the Zeeman-split quantum-dot level in\nthe charge statistics."
    },
    {
        "anchor": "Energy-efficient hybrid spintronic-straintronic reconfigurable bit\n  comparator: We propose a reconfigurable bit comparator implemented with a nanowire spin\nvalve whose two contacts are magnetostrictive with bistable magnetization.\nReference and input bits are \"written\" into the magnetization states of the two\ncontacts with electrically generated strain and the spin-valve's resistance is\nlowered if they match. Multiple comparators can be interfaced in parallel with\na magneto-tunneling junction to determine if an N-bit input stream matches an\nN-bit reference stream bit by bit. The system is robust against thermal noise\nat room temperature and a 16-bit comparator can operate at roughly 416 MHz\nwhile dissipating at most 420 aJ per cycle.",
        "positive": "Magnetic field dependent equilibration of fractional quantum Hall edge\n  modes: Fractional conductance is measured by partitioning $\\nu = 1$ edge state using\ngate-tunable fractional quantum Hall (FQH) liquids of filling 1/3 or 2/3 for\ncurrent injection and detection. We observe two sets of FQH plateaus 1/9, 2/9,\n4/9 and 1/6, 1/3, 2/3 at low and high magnetic field ends of the $\\nu = 1$\nplateau respectively. The findings are explained by magnetic field dependent\nequilibration of three FQH edge modes with conductance $e^2/3h$ arising from\nedge reconstruction. The results reveal remarkable enhancement of the\nequilibration lengths of the FQH edge modes with increasing field."
    },
    {
        "anchor": "$2^n$-root weak, Chern, and higher-order topological insulators, and\n  $2^n$-root topological semimetals: Recently, we have introduced in [A. M. Marques et al., Phys. Rev. B 103,\n235425 (2021)] the concept of $2^n$-root topology and applied it to\none-dimensional systems. These models require $n$ squaring operations to their\nHamiltonians, intercalated with different constant energy downshifts at each\nlevel, in order to arrive at a decoupled block corresponding to a known\ntopological insulator (TI) that acts as the source of the topological features\nof the starting $2^n$-root TI ($\\sqrt[2^n]{\\text{TI}}$). In the process, $n$\nnon-topological residual models with degenerate spectra and in-gap impurity\nstates appear, which dilute the topologically protected component of the\nstarting edge states. Here, we generalize this method to several\ntwo-dimensional models, by finding the 4-root version of lattices hosting weak\nand higher-order boundary modes (both topological and non-topological) of a\nChern insulator and of a topological semimetal. We further show that a starting\nmodel with a non-Hermitian region in parameter space and a complex energy\nspectrum can nevertheless display a purely real spectrum for all its successive\nsquared versions, allowing for an exact mapping between certain non-Hermitian\nmodels and their Hermitian lower root-degree counterparts. A comment is made on\nthe possible realization of these models in artificial lattices.",
        "positive": "Isotropic plasma-thermal atomic layer etching of aluminum nitride using\n  SF$_6$ plasma and Al(CH$_3$)$_3$: We report the isotropic plasma atomic layer etching (ALE) of aluminum nitride\nusing sequential exposures of SF$_6$ plasma and trimethylaluminum\n(Al(CH$_3$)$_3$, TMA). ALE was observed at temperatures greater than 200\n$^\\circ$C, with a maximum etch rate of 1.9 \\r{A}/cycle observed at 300\n$^\\circ$C as measured using ex-situ ellipsometry. After ALE, the etched surface\nwas found to contain a lower concentration of oxygen compared to the original\nsurface and exhibited a $\\sim 35$% decrease in surface roughness. These\nfindings have relevance for applications of AlN in nonlinear photonics and wide\nbandgap semiconductor devices."
    },
    {
        "anchor": "Fingerprint of vortex-like flux closure in isotropic Nd-Fe-B bulk magnet: Taking advantage of recent progress in neutron instrumentation and in the\nunderstanding of magnetic-field-dependent small-angle neutron scattering, here,\nwe study the three-dimensional magnetization distribution within an isotropic\nNd-Fe-B bulk magnet. The magnetic neutron scattering cross section of this\nsystem features the so-called spike anisotropy, which points towards the\npresence of a strong magnetodipolar interaction. This experimental result\ncombined with a damped oscillatory behavior of the corresponding correlation\nfunction and recent micromagnetic simulation results on spherical nanoparticles\nsuggest an interpretation of the neutron data in terms of vortex-like\nflux-closure patterns. The field-dependent correlation length Lc is well\nreproduced by a phenomenological power-law model. While the experimental\nneutron data for Lc are described by an exponent close to unity (p = 0.86), the\nsimulation results yield p = 1.70, posing a challenge to theory to include\nvortex-vortex interaction effects.",
        "positive": "Dispersively detected Pauli Spin-Blockade in a Silicon Nanowire\n  Field-Effect Transistor: We report the dispersive readout of the spin state of a double quantum dot\nformed at the corner states of a silicon nanowire field-effect transistor. Two\nface-to-face top-gate electrodes allow us to independently tune the charge\noccupation of the quantum dot system down to the few-electron limit. We measure\nthe charge stability of the double quantum dot in DC transport as well as\ndispersively via in-situ gate-based radio frequency reflectometry, where one\ntop-gate electrode is connected to a resonator. The latter removes the need for\nexternal charge sensors in quantum computing architectures and provides a\ncompact way to readout the dispersive shift caused by changes in the quantum\ncapacitance during interdot charge transitions. Here, we observe Pauli\nspin-blockade in the high-frequency response of the circuit at finite magnetic\nfields between singlet and triplet states. The blockade is lifted at higher\nmagnetic fields when intra-dot triplet states become the ground state\nconfiguration. A lineshape analysis of the dispersive phase shift reveals\nfurthermore an intradot valley-orbit splitting $\\Delta_{vo}$ of 145 $\\mu$eV.\nOur results open up the possibility to operate compact CMOS technology as a\nsinglet-triplet qubit and make split-gate silicon nanowire architectures an\nideal candidate for the study of spin dynamics."
    },
    {
        "anchor": "Intrinsic Valley-Related Multiple Hall Effect in 2D Organometallic\n  Lattice: Valley-related multiple Hall effect in 2D lattice is a fundamental transport\nphenomenon in the fields of condensed-matter physics and material science. So\nfar, most proposals for its realization are limited to toy models or extrinsic\neffects. Here, based on tight-binding model and first-principles calculations,\nwe report the discovery of intrinsic valley-related multiple Hall effect in 2D\norganometallic lattice of NbTa-benzene. Protected by the breaking of both\ntime-reversal and inversion symmetry, NbTa-benzene exhibits large valley\npolarization spontaneously in both the conduction and valence bands,\nguaranteeing the anomalous valley Hall effect. Simultaneously, because of the\nexchange interaction and strong spin-orbit coupling, intrinsic band inversion\noccurs at one valley, which ensures the valley-polarized quantum anomalous Hall\neffect, thus presenting the extraordinary valley-related multiple Hall effect\nin nature. In addition, it can be transformed into the phase with ferrovalley\nor quantum anomalous Hall effect solely through strain engineering. These\ninsights not only are useful for the fundamental research in valley-related\nphysics, but also enable a wide range of novel device applications.",
        "positive": "Direct Measurement of Quantum Dot Spin Dynamics using Time-Resolved\n  Resonance Fluorescence: We temporally resolve the resonance fluorescence from an electron spin\nconfined to a single self-assembled quantum dot to measure directly the spin's\noptical initialization and natural relaxation timescales. Our measurements\ndemonstrate that spin initialization occurs on the order of microseconds in the\nFaraday configuration when a laser resonantly drives the quantum dot\ntransition. We show that the mechanism mediating the optically induced\nspin-flip changes from electron-nuclei interaction to hole-mixing interaction\nat 0.6 Tesla external magnetic field. Spin relaxation measurements result in\ntimes on the order of milliseconds and suggest that a $B^{-5}$ magnetic field\ndependence, due to spin-orbit coupling, is sustained all the way down to 2.2\nTesla."
    },
    {
        "anchor": "Charge-vibration interaction effects in normal-superconductor quantum\n  dots: We study the quantum transport and the nonequilibrium vibrational states of a\nquantum dot embedded between a normal and a superconducting lead with the\ncharge on the quantum dot linearly coupled to a harmonic oscillator of\nfrequency $\\omega$. To the leading order in the charge-vibration interaction,\nwe calculate the current and the nonequilibrium phonon occupation by the\nKeldsyh Green's function technique. We analyze the inelastic,\nvibration-assisted tunneling processes in the regime $\\omega <\\Delta$, with the\nsuperconducting energy gap $\\Delta$, and for sharp resonant transmission\nthrough the dot. When the energy $\\varepsilon_0$ of the dot's level is close to\nthe Fermi energy $\\mu$, i.e. $|\\varepsilon_0-\\mu|\\ll \\Delta$, inelastic Andreev\nreflections dominate up to voltage $eV\\gtrsim\\Delta$. The inelastic\nquasiparticle tunneling becomes the leading process when the dot's level is\nclose to the gap $|\\varepsilon_0-\\mu|\\sim \\Delta \\pm \\omega$. In both cases,\nthe inelastic tunneling processes appear as sharp and prominent peaks - not\nbroadened by temperature - in the $I$-$V$ characteristic and pave the way for\ninelastic spectroscopy of vibrational modes even at temperatures $T \\gg\n\\omega$. We also found that inelastic Andreev reflections as well as\nquasiparticle tunneling induce a strong nonequilibrium state of the oscillator.\nIn different ranges on the dot's level, we found that the current produces: (i)\nground-state cooling of the oscillator with phonon occupation $n\\ll 1$, (ii)\naccumulation of energy in the oscillator with $n\\gg 1$ and (iii) a mechanical\ninstability which is a precursor of self-sustained oscillations. We show that\nground-state cooling is achieved simultaneously for several modes of different\nfrequencies. Finally, we discuss how the nonequilibrium vibrational state can\nbe detected by the asymmetric behavior of the inelastic current peaks respect\nto the gate voltage.",
        "positive": "Electron interferometer formed with a scanning probe tip and quantum\n  point contact: We show an electron interferometer between a quantum point contact (QPC) and\na scanning gate microscope (SGM) tip in a two-dimensional electron gas. The QPC\nand SGM tip act as reflective barriers of a lossy cavity; the conductance\nthrough the system thus varies as a function of the distance between the QPC\nand SGM tip. We characterize how temperature, electron wavelength, cavity\nlength, and reflectivity of the QPC barrier affect the interferometer. We\nreport checkerboard interference patterns near the QPC and, when injecting\nelectrons above or below the Fermi energy, effects of dephasing."
    },
    {
        "anchor": "Hot Carrier Extraction Using Energy Selective Contacts and Its Impact on\n  the Limiting Efficiency of a Hot Carrier Solar Cell: Extraction of charge carriers from a hot carrier solar cell using energy\nselective contacts, and the impact on limiting power conversion efficiency is\nanalyzed. It is shown that assuming isentropic conversion of carrier heat into\nvoltage implies zero power output at all operating points. Under conditions of\npower output, lower voltages than in the isentropic case are obtained due to\nthe irreversible entropy increase associated with carrier flow. This lowers the\nlimiting power conversion efficiency of a hot carrier solar cell.",
        "positive": "A capacitance spectroscopy-based platform for realizing gate-defined\n  electronic lattices: Electrostatic confinement in semiconductors provides a flexible platform for\nthe emulation of interacting electrons in a two-dimensional lattice, including\nin the presence of gauge fields. This combination offers the potential to\nrealize a wide host of quantum phases. Here we present a measurement and\nfabrication scheme that builds on capacitance spectroscopy and allows for the\nindependent control of density and periodic potential strength imposed on a\ntwo-dimensional electron gas. We characterize disorder levels and\n(in)homogeneity and develop and optimize different gating strategies at length\nscales where interactions are expected to be strong. A continuation of these\nideas might see to fruition the emulation of interaction-driven Mott\ntransitions or Hofstadter butterfly physics."
    },
    {
        "anchor": "Absence of split pairs in the cross-correlations of a highly transparent\n  normal metal-superconductor-normal metal electron beam splitter: The nonlocal conductance and the current cross-correlations are investigated\nwithin scattering theory for three-terminal normal metal-superconductor-normal\nmetal (NSN) hybrid structures. The positive cross-correlations at high\ntransparency found by M\\'elin, Benjamin and Martin [Phys. Rev. B 77, 094512\n(2008)] are not due to crossed Andreev reflection. On the other hand, local\nprocesses can be enhanced by reflectionless tunneling but this mechanism has\nlittle influence on nonlocal processes and on current cross-correlations.\nTherefore Cooper pair splitting cannot be enhanced by reflectionless tunneling.\nOverall, this shows that NSN structures with highly transparent or effectively\nhighly transparent interfaces are not suited to experimentally producing\nentangled split pairs of electrons.",
        "positive": "Coupled collective and Rabi oscillations triggered by electron transport\n  through a photon cavity: We show how the switching-on of an electron transport through a system of two\nparallel quantum dots embedded in a short quantum wire in a photon cavity can\ntrigger coupled Rabi and collective electron-photon oscillations. We select the\ninitial state of the system to be an eigenstate of the closed system containing\ntwo Coulomb interacting electrons with possibly few photons of a single cavity\nmode. The many-level quantum dots are described by a continuous potential. The\nCoulomb interaction and the para- and dia-magnetic electron-photon interactions\nare treated by exact diagonalization in a truncated Fock-space. To identify the\ncollective modes the results are compared for an open and a closed system with\nrespect to the coupling to external electron reservoirs, or leads. We\ndemonstrate that the vacuum Rabi oscillations can be seen in transport\nquantities as the current in and out of the system."
    },
    {
        "anchor": "Generic coexistence of Fermi arcs and Dirac cones on the surface of\n  time-reversal invariant Weyl semimetals: The hallmark of Weyl semimetals is the existence of open constant-energy\ncontours on their surface -- the so-called Fermi arcs -- connecting Weyl\npoints. Here, we show that for time-reversal symmetric realizations of Weyl\nsemimetals these Fermi arcs in many cases coexist with closed Fermi pockets\noriginating from surface Dirac cones pinned to time-reversal invariant momenta.\nThe existence of Fermi pockets is required for certain Fermi-arc connectivities\ndue to additional restrictions imposed by the six $\\mathbb{Z}_2$ topological\ninvariants characterizing a generic time-reversal invariant Weyl semimetal. We\nshow that a change of the Fermi-arc connectivity generally leads to a different\ntopology of the surface Fermi surface, and identify the half-Heusler compound\nLaPtBi under in-plane compressive strain as a material that realizes this\nsurface Lifshitz transition. We also discuss universal features of this\ncoexistence in quasi-particle interference spectra.",
        "positive": "Thickness-dependent phase transition in graphite under high magnetic\n  field: Various electronic phases emerge when applying high magnetic fields in\ngraphite. However, the origin of a semimetal-insulator transition at $B \\simeq\n30\\; \\textrm{T}$ is still not clear, while an exotic density-wave state is\ntheoretically proposed. In order to identify the electronic state of the\ninsulator phase, we investigate the phase transition in thin-film graphite\nsamples that were fabricated on silicon substrate by a mechanical exfoliation\nmethod. The critical magnetic fields of the semimetal-insulator transition in\nthin-film graphite shift to higher magnetic fields, accompanied by a reduction\nin temperature dependence. These results can be qualitatively reproduced by a\ndensity-wave model by introducing a quantum size effect. Our findings establish\nthe electronic state of the insulator phase as a density-wave state standing\nalong the out-of-plane direction, and help determine the electronic states in\nother high-magnetic-field phases."
    },
    {
        "anchor": "Detecting parity effect in a superconducting device in the presence of\n  parity switches: We present a superconducting device showing a clear parity effect in the\nnumber of electrons, even when there is, on average, a single nonequilibrium\nquasiparticle present and the parity of the island switches due to\nquasiparticles tunneling in and out of the device at rates on the order of 100\nHz. We detect the switching by monitoring in real time the charge state of a\nsuperconducting island connected to normal leads by tunnel junctions. The\nquasiparticles are created by Cooper pairs breaking on the island at a rate of\na few kHz. We demonstrate that the pair breaking is caused by the backaction of\nthe single-electron transistor used as a charge detector. With sufficiently low\nprobing currents, our superconducting island is free of quasiparticles 97% of\nthe time.",
        "positive": "Polariton crystallization in driven arrays of lossy nonlinear resonators: We investigate the steady states of a lossy array of nonlinear optical\nresonators that are driven by lasers and interact via mutual photon tunneling.\nFor weak nonlinearities, we find two-mode squeezing of polaritons in modes\nwhose quasi-momenta match the relative phases of the laser drives. For strong\nnonlinearities the spatial polariton density-density correlations indicate that\nthe polaritons crystallize and are predominantly found at a specific distance\nfrom each other despite being injected by a coherent light source and damped by\nthe environment."
    },
    {
        "anchor": "Nanomaterial datasets to advance tomography in scanning transmission\n  electron microscopy: Electron tomography in materials science has flourished with the demand to\ncharacterize nanoscale materials in three dimensions (3D). Access to\nexperimental data is vital for developing and validating reconstruction methods\nthat improve resolution and reduce radiation dose requirements. This work\npresents five high-quality scanning transmission electron microscope (STEM)\ntomography datasets in order to address the critical need for open access data\nin this field. The datasets represent the current limits of experimental\ntechnique, are of high quality, and contain materials with structural\ncomplexity. Included are tomographic series of a hyperbranched Co2P\nnanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the\ncomplete 180{\\deg} tilt range, a platinum nanoparticle and a tungsten needle\nboth imaged at atomic resolution by equal slope tomography, and a through-focal\ntilt series of PtCu nanoparticles. A volumetric reconstruction from every\ndataset is provided for comparison and development of post-processing and\nvisualization techniques. Researchers interested in creating novel data\nprocessing and reconstruction algorithms will now have access to state of the\nart experimental test data.",
        "positive": "Feedback-charging a metallic island: We consider electronic transport through a single-electron quantum dot that\nis tunnel-coupled to an electronic lead and a metallic island. A background\nreservoir keeps the metallic island at a thermal state with the ambient\ntemperature, while the charge accumulated on the island is reflected in a\ntime-dependent chemical potential. Without feedback, a current would flow\nthrough the system until the chemical potentials of island and lead are\nequilibrated. A feedback loop can be implemented by a quantum point contact\ndetecting the dot state, classical processing of the result and appropriate\nfeedback actions on the electronic tunneling rates taken, with the objective to\ndirect the current in a preferred direction. Since we directly take the\ndetector counting statistics into account, this automatically includes\nmeasurement errors in the description. When mainly the rates are modified but\nhardly any energy is exchanged with the system, this feedback loop effectively\nimplements a Maxwell demon, capable of transporting electrons against an\nelectric bias and thereby charging the metallic island. Once the feedback\nprotocol is stopped, the metallic island simply discharges. We find that a\nquantitative detector model may be useful for a realistic statistical\ndescription of feedback loops."
    },
    {
        "anchor": "One-dimensional transport in hybrid metal-semiconductor nanotube systems: We develop an electron transport theory for the hybrid system of a\nsemiconducting carbon nanotube that encapsulates a one-atom-thick metallic\nwire. The theory predicts Fano resonances in electron transport through the\nsystem, whereby the interaction of electrons on the wire with nanotube plasmon\ngenerated near-fields blocks some of the wire transmission channels to open up\nthe new coherent plasmon-mediated channel in the nanotube forbidden gap outside\nthe wire transmission band. Such a channel makes the entire hybrid system\ntransparent in the energy domain where neither wire, nor nanotube is\nindivudually transparent. This effect can be used to manipulate by the electron\ncharge transfer in hybrid nanodevices built on metal-semiconductor nanotube\nsystems.",
        "positive": "Electronic transport in graphene-based structures: an effective cross\n  section approach: We show that transport in low-dimensional carbon structures with finite\nconcentrations of scatterers can be modeled by utilising scaling theory and\neffective cross sections. Our reults are based on large scale numerical\nsimulations of carbon nanotubes and graphene nanoribbons, using a tightbinding\nmodel with parameters obtained from first principles electronic structure\ncalculations. As shown by a comprehensive statistical analysis, the scattering\ncross sections can be used to estimate the conductance of a quasi-1D system\nboth in the Ohmic and localized regimes. They can be computed with good\naccuracy from the transmission functions of single defects, greatly reducing\nthe computational cost and paving the way towards using first principles\nmethods to evaluate the conductance of mesoscopic systems, consisting of\nmillions of atoms."
    },
    {
        "anchor": "Scanning tunneling spectroscopy reveals a silicon dangling bond charge\n  state transition: We report the study of single dangling bonds (DB) on the hydrogen terminated\nsilicon (100) surface using a low temperature scanning tunneling microscope\n(LT-STM). By investigating samples prepared with different annealing\ntemperatures, we establish the critical role of subsurface arsenic dopants on\nthe DB electronic properties. We show that when the near surface concentration\nof dopants is depleted as a result of $1250{\\deg}C$ flash anneals, a single DB\nexhibits a sharp conduction step in its I(V) spectroscopy that is not due to a\ndensity of states effect but rather corresponds to a DB charge state\ntransition. The voltage position of this transition is perfectly correlated\nwith bias dependent changes in STM images of the DB at different charge states.\nDensity functional theory (DFT) calculations further highlight the role of\nsubsurface dopants on DB properties by showing the influence of the DB-dopant\ndistance on the DB state. We discuss possible theoretical models of electronic\ntransport through the DB that could account for our experimental observations.",
        "positive": "Spin Bose Glass Phase in Bilayer Quantum Hall Systems at $\u03bd=2$: We develop an effective spin theory to describe magnetic properties of the\n$\\nu=2$ Quantum Hall bilayer systems. In the absence of disorder this theory\ngives quantitative agreement with the results of microscopic Hartree-Fock\ncalculations, and for finite disorder it predicts the existence of a novel spin\nBose glass phase. The Bose glass is characterized by the presence of domains of\ncanted antiferromagnetic phase with zero average antiferromagnetic order and\nshort range mean antiferromagnetic correlations. It has infinite\nantiferromagnetic transverse susceptibility, finite longitudinal spin\nsusceptibility and specific heat linear in temperature. Transition from the\ncanted antiferromagnet phase to the spin Bose glass phase is characterized by a\nuniversal value of the longitudinal spin conductance."
    },
    {
        "anchor": "Polariton gap and gap-stripe solitons in Zeeman lattices: We predict that spatially modulated Zeeman splitting resulting in the\nformation of Zeeman lattice can be used for creation of localized\nself-sustained excitations in spinor polariton condensates with dominant\nrepulsive interactions. In such lattices, the phenomenon of TE-TM splitting,\nplaying the role of effective spin-orbit interaction, leads to the emergence of\nthe stripe phase and formation of stable gap-stripe solitons with complex\nintrinsic structure resulting from the presence of two characteristic spatial\nscales, one of which is set by the period of Zeeman lattice, while other is set\nby the momentum in the depth of the Brillouin zone, at which such solitons\nbifurcate from the linear spectrum. Gap-stripe polariton solitons can be\nexcited by suitable resonant pump.",
        "positive": "Chiral metals and entrapped insulators in a one-dimensional topological\n  non-Hermitian system: In this work we study many-body 'steady states' that arise in the\nnon-Hermitian generalisation of the non-interacting Su-Schrieffer-Heeger model\nat a finite density of fermions. We find that the hitherto known phase diagrams\nfor this system, derived from the single-particle gap closings, in fact\ncorrespond to distinct non-equilibrium phases, which either carry finite\ncurrents or are dynamical insulators where particles are entrapped. Each of\nthese have distinct quasi-particle excitations and steady state correlations\nand entanglement properties. Looking at finite-sized systems, we further\nmodulate the boundary to uncover the topological features in such steady states\n-- in particular the emergence of leaky boundary modes. Using a variety of\nanalytical and numerical methods we develop a theoretical understanding of the\nvarious phases and their transitions, and uncover the rich interplay of\nnon-equilibrium many-body physics, quantum entanglement and topology in a\nsimple looking, yet a rich model system."
    },
    {
        "anchor": "Majorana Fermions in Honeycomb Lattices: We study the formation of Majorana fermions in honeycomb-lattice structures\nin the presence of a Zeeman field, Rashba spin-orbit coupling, and in the\nproximity of an s-wave superconductor. We show that an exact mapping exists\nbetween an anisotropic hexagonal-lattice nanoribbon at k = 0 and a\none-dimensional chain, for which the existence of Majorana fermions has been\nextensively discussed. Consequently we can predict the conditions for the\nemergence of Majorana fermions at the edges of such ribbon, and relate the\nexistence of Majoranas to a band inversion in the bulk band structure. Moreover\nwe find that similar situations arise in isotropic lattices and we give some\nexamples which show the formation of Majorana fermions in these structures.",
        "positive": "Short vs. long range exchange interactions in twisted bilayer graphene: We discuss the effect of long-range interactions within the self-consistent\nHartree-Fock (HF) approximation in comparison to short-range atomic Hubbard\ninteractions on the band structure of twisted bilayer graphene (TBG) at charge\nneutrality for various twist angles. Starting from atomistic calculations, we\ndetermine the quasi-particle band structure of TBG with Hubbard interactions\nfor various magnetic orderings: modulated anti-ferromagnetic (MAFM), nodal\nanti-ferromagnetic (NAFM) and hexagonal anti-ferromagnetic (HAFM). Then, we\ndevelop an approach to incorporate these magnetic orderings along with the HF\npotential in the continuum approximation. Away from the magic angle, we observe\na drastic effect of the magnetic order on the band structure of TBG compared to\nthe influence of the HF potential. Near the magic angle, however, the HF\npotential seems to play a major role on the band structure compared to the\nmagnetic order. These findings suggest that the spin-valley degenerate broken\nsymmetry state often found in HF calculations of charge neutral TBG near the\nmagic angle should favour magnetic order, since the atomistic Hubbard\ninteraction will break this symmetry in favour of spin polarization."
    },
    {
        "anchor": "VLS-HVPE growth of ultra-long and defect-free GaAs nanowires\n  investigated by ab initio simulation coupled to near-field microscopy: High aspect ratio, rod-like and single crystal phase GaAs nanowires (NWs)\nwere grown by gold catalyst-assisted hydride vapor phase epitaxy (HVPE). High\nresolution transmission electron microscopy (HRTEM) and micro-Raman\nspectroscopy revealed polytypism-free zinc blende NWs over lengths of several\ntens of micrometers for diameters ranging between 50 and 150 nm.\nMicro-photoluminescence studies of individual NWs showed linewidths smaller\nthan those reported elsewhere which is consistent with the crystalline quality\nof the NWs. HVPE makes use of chloride growth precursors of which high\ndecomposition frequency, after adsorption onto the catalyst particle, favors a\ndirect and rapid introduction of the Ga atoms from the vapor phase into the\ncatalyst liquid droplet. This yields high axial growth rate (more than 100\nmicron/h) of NWs. The fast diffusion of the Ga atoms in the droplet towards the\ninterface between the liquid and the solid nanowire was investigated by using\ndensity functional theory calculations. The diffusion coefficient of Ga atoms\nwas estimated to be 3x10-9 m2/s, which matches the experimental observations.",
        "positive": "Oscillating planar Hall response from the surface electrons in bulk\n  crystal Sn doped Bi1.1Sb0.9Te2S: We report the low-temperature magneto-transport in the bulk-insulating single\ncrystal of topological insulator Sn doped Bi1.1Sb0.9Te2S. The Shubnikov-de Haas\noscillations appear with their reciprocal frequency proportional to cos/theta ,\ndemonstrating the dominant transport of topological surface states. While the\nmagnetic field is rotating in the sample surface, the planar Hall effect arises\nwith sizeable oscillations following a relation of cos/theta sin/theta . Its\namplitude reaches the maximum at the lowest temperature and drops to nearly\nzero at the temperature higher than 100 K. All these evidences consolidate such\nplanar Hall oscillations as a new golden criterion on the topological surface\ntransport."
    },
    {
        "anchor": "Topological phase diagram and saddle point singularity in a tunable\n  topological crystalline insulator: We report the evolution of the surface electronic structure and surface\nmaterial properties of a topological crystalline insulator (TCI) Pb1-xSnxSe as\na function of various material parameters including composition x, temperature\nT and crystal structure. Our spectroscopic data demonstrate the electronic\ngroundstate condition for the saddle point singularity, the tunability of\nsurface chemical potential, and the surface states' response to circularly\npolarized light. Our results show that each material parameter can tune the\nsystem between trivial and topological phase in a distinct way unlike as seen\nin Bi2Se3 and related compounds, leading to a rich and unique topological phase\ndiagram. Our systematic studies of the TCI Pb1-xSnxSe are valuable materials\nguide to realize new topological phenomena.",
        "positive": "Generic helical edge states due to Rashba spin-orbit coupling in a\n  topological insulator: We study the helical edge states of a two-dimensional topological insulator\nwithout axial spin symmetry due to the Rashba spin-orbit interaction. Lack of\naxial spin symmetry can lead to so-called generic helical edge states, which\nhave energy-dependent spin orientation. This opens the possibility of inelastic\nbackscattering and thereby nonquantized transport. Here we find analytically\nthe new dispersion relations and the energy dependent spin orientation of the\ngeneric helical edge states in the presence of Rashba spin-orbit coupling\nwithin the Bernevig-Hughes-Zhang model, for both a single isolated edge and for\na finite width ribbon. In the single-edge case, we analytically quantify the\nenergy dependence of the spin orientation, which turns out to be weak for a\nrealistic HgTe quantum well. Nevertheless, finite size effects combined with\nRashba spin-orbit coupling result in two avoided crossings in the energy\ndispersions, where the spin orientation variation of the edge states is very\nsignificantly increased for realistic parameters. Finally, our analytical\nresults are found to compare well to a numerical tight-binding regularization\nof the model."
    },
    {
        "anchor": "Analytic solution to pseudo-Landau levels in strongly bent graphene\n  nanoribbons: Nonuniform elastic strain is known to induce pseudo-Landau levels in Dirac\nmaterials. But these pseudo-Landau levels are hardly resolvable in an analytic\nfashion when the strain is strong, because of the emerging complicated space\ndependence in both the strain-modulated Fermi velocity and the strain-induced\npseudomagnetic field. We analytically characterize the solution to the\npseudo-Landau levels in experimentally accessible strongly bent graphene\nnanoribbons, by treating the effects of the nonuniform Fermi velocity and\npseudomagnetic field on equal footing. The analytic solution is detectable\nthrough the angle-resolved photoemission spectroscopy (ARPES) and allows\nquantitative comparison between theories and various transport experiments,\nsuch as the Shubnikov-de Haas oscillation in the complete absence of magnetic\nfields and the negative strain-resistivity resulting from the valley anomaly.\nThe analytic solution can be generalized to twisted two-dimensional materials\nand topological materials and will shed a new light on the related experimental\nexplorations and straintronics applications.",
        "positive": "Untangling the valley structure of states for intravalley exchange\n  anisotropy in lead chalcogenides quantum dots: We put forward a generalized procedure which allows to restore the bulk-like\nelectron and hole wave functions localized in certain valleys from the wave\nfunctions of quantum confined electron/hole states obtained in atomistic\ncalculations of nanostructures. As a demonstration, the procedure is applied to\nthe lead chalcogenide quantum dots to extract the effective intravalley\nHamiltonian of the exchange interaction for the ground exciton state PbS and\nPbSe quantum dots. Renormalization of the anisotropic intravalley matrix\nelemets of velocity is also calculated. The results demonstrate that the matrix\nelements of intravalley exchange in PbS quantum dots are much more anisotropic\nthan ones in PbSe."
    },
    {
        "anchor": "Generating extreme quantum scattering in graphene with machine learning: Graphene quantum dots provide a platform for manipulating electron behaviors\nin two-dimensional (2D) Dirac materials. Most previous works were of the\n\"forward\" type in that the objective was to solve various confinement,\ntransport and scattering problems with given structures that can be generated\nby, e.g., applying an external electrical field. There are applications such as\ncloaking or superscattering where the challenging problem of inverse design\nneeds to be solved: finding a quantum-dot structure according to certain\ndesired functional characteristics. A brute-force search of the system\nconfiguration based directly on the solutions of the Dirac equation is\ncomputational infeasible. We articulate a machine-learning approach to\naddressing the inverse-design problem where artificial neural networks subject\nto physical constraints are exploited to replace the rigorous Dirac equation\nsolver. In particular, we focus on the problem of designing a quantum dot\nstructure to generate both cloaking and superscattering in terms of the\nscattering efficiency as a function of the energy. We construct a physical loss\nfunction that enables accurate prediction of the scattering characteristics. We\ndemonstrate that, in the regime of Klein tunneling, the scattering efficiency\ncan be designed to vary over two orders of magnitudes, allowing any scattering\ncurve to be generated from a proper combination of the gate potentials. Our\nphysics-based machine-learning approach can be a powerful design tool for 2D\nDirac material-based electronics.",
        "positive": "Democratizing Spin Qubits: I've been building Powerpoint-based quantum computers with electron spins in\nsilicon for 20 years. Unfortunately, real-life-based quantum dot quantum\ncomputers are harder to implement. Materials, fabrication, and control\nchallenges still impede progress. The way to accelerate discovery is to make\nand measure more qubits. Here I discuss separating the qubit realization and\ntesting circuitry from the materials science and on-chip fabrication that will\nultimately be necessary. This approach should allow us, in the shorter term, to\ncharacterize wafers non-invasively for their qubit-relevant properties, to make\nsmall qubit systems on various different materials with little extra cost, and\neven to test spin-qubit to superconducting cavity entanglement protocols where\nthe best possible cavity quality is preserved. Such a testbed can advance the\nmaterials science of semiconductor quantum information devices and enable small\nquantum computers. This article may also be useful as a light and light-hearted\nintroduction to quantum dot spin qubits."
    },
    {
        "anchor": "All-optical band engineering of gapped Dirac materials: We demonstrate theoretically that the interaction of electrons in gapped\nDirac materials (gapped graphene and transition-metal dichalchogenide\nmonolayers) with a strong off-resonant electromagnetic field (dressing field)\nsubstantially renormalizes the band gaps and the spin-orbit splitting.\nMoreover, the renormalized electronic parameters drastically depend on the\nfield polarization. Namely, a linearly polarized dressing field always\ndecreases the band gap (and, particularly, can turn the gap into zero), whereas\na circularly polarized field breaks the equivalence of valleys in different\npoints of the Brillouin zone and can both increase and decrease corresponding\nband gaps. As a consequence, the dressing field can serve as an effective tool\nto control spin and valley properties of the materials and be potentially\nexploited in optoelectronic applications.",
        "positive": "Quantum statistics of photon from a semiconductor microcavity embedded\n  with a graphene nanoribbon: In this work we have studied the quantum statistical properties of the photon\nemitted from a driven microcavity embedded with a single armchair-edged\ngraphene nanoribbon (GNR). The system is coherently pumped with weak laser\namplitude. Analytical expressions are derived in both strong and weak coupling\nregimes and the nonclassical proprieties of the emitted field have been\ninvestigated. Furthermore, it is concluded that this excitonic system presents\nseveral statistical similarities to the atomic system, in particular for the\nbad-cavity and good-cavity limits in the weak laser amplitude regime. We have\nshown that independently of the excitonic nonlinearity, which describes the\ninteraction strength of the excitons in GNRs, the autocorrelation function is\nantibunched for an exciton cooperativity value range. More interestingly, it is\ndemonstrated that the exciton-exciton interaction strength in GNR can be\ndeduced from the value of the autocorrelation function at zero time delay of\n{\\tau}=0. Our theoretical results demonstrated that a microcavity embedded with\na single GNR can serve as a nanophotonic device and a useful analysis method\nfor a deep understanding of excitonic properties of GNRs."
    },
    {
        "anchor": "Current-Modulated Magnetoplasmonic Devices: We model the operation and readout sensitivity of two current-modulated\nmagnetoplasmonic devices which exploit spin Hall effect-like behavior as a\nfunction of their device and material parameters. In both devices, current\npulses are applied to an electrically-isolated stack, containing an active\nlayer (either a metal with large spin orbit coupling or a topological\ninsulator) embedded within a plasmonic metal (Au). The first device, composed\nof a ferromagnet and the active layer, illustrates a plasmonic readout scheme\nfor detecting magnetic reorientation driven by current-induced spin transfer\ntorques. The plasmonic readout of these current-modulated non-volatile states\nmay facilitate the development of plasmon-based memory or logic devices. The\nsecond device, containing only the active layer, explores the magnetoplasmonic\nreadout conditions required to directly measure the spin accumulation in these\nmaterials. The estimated thickness-dependent sensitivity agrees with recent\nexperimental magneto-optical Kerr effect observations.",
        "positive": "Low-temperature behavior of transmission phase shift across a Kondo\n  correlated quantum dot: We study the transmission phase shift across a Kondo correlated quantum dot\nin a GaAs heterostructure at temperatures below the Kondo temperature ($T <\nT_{\\rm K}$), where the phase shift is expected to show a plateau at $\\pi/2$ for\nan ideal Kondo singlet ground state. Our device is tuned such that the ratio\n$\\Gamma/U$ of level width $\\Gamma$ to charging energy $U$ is quite large\n($\\lesssim 0.5$ rather than $\\ll 1$). This situation is commonly used in GaAs\nquantum dots to ensure Kondo temperatures large enough ($\\simeq 100$ mK here)\nto be experimentally accessible; however it also implies that charge\nfluctuations are more pronounced than typically assumed in theoretical studies\nfocusing on the regime $\\Gamma/U \\ll 1$ needed to ensure a well-defined local\nmoment. Our measured phase evolves monotonically by $\\pi$ across the two\nCoulomb peaks, but without being locked at $\\pi/2$ in the Kondo valley for $T\n\\ll T_{\\rm K}$, due to a significant influence of large $\\Gamma/U$. Only when\n$\\Gamma/U$ is reduced sufficiently does the phase start to be locked around\n$\\pi/2$ and develops into a plateau at $\\pi/2$. Our observations are consistent\nwith numerical renormalization group calculations, and can be understood as a\ndirect consequence of the Friedel sum rule that relates the transmission phase\nshift to the local occupancy of the dot, and thermal average of a transmission\ncoefficient through a resonance level near the Fermi energy."
    },
    {
        "anchor": "Direct Spectroscopic Observation of Berry Phase Interference in the\n  Ni$_4$ Single-Molecule Magnet: Berry phase effects in spin systems lead to the suppression of tunneling\neffects when different tunneling paths interfere destructively. Such effects\nhave been seen in several single-molecule magnets (SMMs) through measurements\nof magnetization dynamics, where the experimental signal may arise from the\ncontributions of numerous energy levels. Here we present experimental\nmeasurements of Berry phase interference effects that are determined through\nelectron-spin resonance on a four-fold symmetric SMM. Specifically, we measure\ntransitions between tunnel-split excited states in the Ni$_4$ SMM in the\npresence of a transverse field in the hard plane of the crystalline sample. By\nusing a home-built rotation apparatus, the direction of the sample can be\nchanged \\textit{in situ} so that that the field direction can be swept through\nthe entire hard plane of the sample. When the field is in certain directions in\nthe plane, we observe a splitting of the transition, a hallmark of Berry phase\ninterference. The experimental results are well reproduced by theoretical\npredictions, and fitting of the data provides information about the effects of\ndipolar interactions and sample misalignment.",
        "positive": "Anomalous Hall effect in granular ferromagnetic metals and effects of\n  weak localization: We theoretically investigate the anomalous Hall effect in a system of\ndense-packed ferromagnetic grains in the metallic regime. Using the formalism\nrecently developed for the conventional Hall effect in granular metals, we\ncalculate the residual anomalous Hall conductivity $\\sigma_{xy}$ and\nresistivity $\\rho_{xy}$ and weak localization corrections to them for both\nskew-scattering and side-jump mechanisms. We find that, unlike for\nhomogeneously disordered metals, the scaling relation between $\\rho_{xy}$ and\nthe longitudinal resistivity $\\rho_{xx}$ does not hold. The weak localization\ncorrections, however, are found to be in agreement with those for homogeneous\nmetals. We discuss recent experimental data on the anomalous Hall effect in\npolycrystalline iron films in view of the obtained results."
    },
    {
        "anchor": "Local and non-local thermopowers in three-terminal nanostructures: The thermoelectric effects in three-terminal structures with a quantum dot\nare considered. We propose the experimentally consistent protocol for\ndetermination of the transport coefficients in terms of the local and non-local\nconductances and thermopowers that can be measured in two steps, applying the\n`four probe technique'. This proposal is compared with other approaches\ndiscussed so far in the literature. As an example we study in detail the\nthermopower induced by the superconducting electrode in a subgap regime which\nmight be useful for analysis of novel hybrid devices.",
        "positive": "Circular dichroism of magneto-phonon resonance in doped graphene: Polarization resolved, Raman scattering response due to E$_{2g}$ phonon in\nmonolayer graphene has been investigated in magnetic fields up to 29 T. The\nhybridization of the E$_{2g}$ phonon with only the fundamental inter Landau\nlevel excitation (involving the n=0 Landau level) is observed and only in one\nof the two configurations of the circularly crossed polarized excitation and\nscattered light. This polarization anisotropy of the magneto-phonon resonance\nis shown to be inherent to relatively strongly doped graphene samples, with\ncarrier concentration typical for graphene deposited on SiO$_2$."
    },
    {
        "anchor": "Optimized spin-injection efficiency and spin MOSFET operation based on\n  low-barrier ferromagnet/insulator/n-Si tunnel contact: We theoretically investigate the spin injection in different FM/I/n-Si tunnel\ncontacts by using the lattice NEGF method. We find that the tunnel contacts\nwith low barrier materials such as TiO$_2$ and Ta$_{2}$O$_{5}$, have much lower\nresistances than the conventional barrier materials, resulting in a wider and\nattainable optimum parameters window for improving the spin injection\nefficiency and MR ratio of a vertical spin MOSFET. Additionally, we find the\nspin asymmetry coefficient of TiO$_2$ tunnel contact has a negative value,\nwhile that of Ta$_{2}$O$_{5}$ contact can be tuned between positive and\nnegative values, by changing the parameters.",
        "positive": "Multiphoton microwave photoresistance in a high-mobility two-dimensional\n  electron gas: We report on experimental and theoretical studies of microwave-induced\nresistance oscillations in a two-dimensional electron gas over a wide range of\nmicrowave intensities. We observe a distinct crossover from linear to sublinear\npower dependence of the oscillation amplitude and a concomitant narrowing of\nthe oscillation extrema. To explain our observations we propose a theory based\non the quantum kinetic equation at arbitrary microwave power. Taken together,\nthese findings demonstrate a crucial role of multiphoton processes at elevated\nmicrowave intensities."
    },
    {
        "anchor": "Mesoscopic transport in two-dimensional topological insulators: Topological states of matter have attracted a lot of attention due to their\nmany intriguing transport properties. In particular, two-dimensional\ntopological insulators (2D TI) possess gapless counter propagating conducting\nedge channels, with opposite spin, that are topologically protected from\nbackscattering. Two basic features are supposed to confirm the existence of the\nballistic edge channels in the submicrometer limit: the 4-terminal conductance\nis expected to be quantized at the universal value $2e^{2}/h$, and a nonlocal\nsignal should appear due to a net current along the sample edge, carried by the\nhelical states. On the other hand for longer channels the conductance has been\nfound to deviate from the quantized value. This article reviewer the\nexperimental and theoretical work related to the transport in two-dimensional\ntopological insulators (2D-TI), based on HgTe quantum wells in zero magnetic\nfield. We provide an overview of the basic mechanisms predicting a deviation\nfrom the quantized transport due to backscattering (accompanied by spin-flips)\nbetween the helical channels. We discuss the details of the model, which takes\ninto account the edge and bulk contribution to the total current and reproduces\nthe experimental results.",
        "positive": "Re-entrant magic-angle phenomena in twisted bilayer graphene in integer\n  magnetic fluxes: In this work we address the re-entrance of magic-angle phenomena (band\nflatness and quantum-geometric transport) in twisted bilayer graphene (TBG)\nsubjected to strong magnetic fluxes $\\pm \\Phi_0$, $\\pm 2 \\Phi_0$, $\\pm 3\n\\Phi_0$... ($\\Phi_0 = h/e$ is the flux quantum per moir\\'e cell). The moir\\'e\ntranslation invariance is restored at the integer fluxes, for which we\ncalculate the TBG band structure using accurate atomistic models with lattice\nrelaxations. Similarly to the zero-flux physics outside the magic angle\ncondition, the reported effect breaks down rapidly with the twist. We conclude\nthat the magic-angle physics re-emerges in high magnetic fields, witnessed by\nthe appearance of flat electronic bands distinct from Landau levels, and\nmanifesting non-trivial quantum geometry. We further discuss the possible\nflat-band quantum geometric contribution to the superfluid weight in strong\nmagnetic fields (28 T at 1.08$^\\circ$ twist), according to Peotta-T\\\"{o}rm\\\"{a}\nmechanism."
    },
    {
        "anchor": "Linear and non-linear transport across a finite Kitaev chain: an exact\n  analytical study: We present exact analytical results for the differential conductance of a\nfinite Kitaev chain in an N-S-N configuration, where the topological\nsuperconductor is contacted on both sides with normal leads. Our results are\nobtained with the Keldysh non-equilibrium Green's functions technique, using\nthe full spectrum of the Kitaev chain without resorting to minimal models. A\nclosed formula for the linear conductance is given, and the analytical\nprocedure to obtain the differential conductance for the transport mediated by\nhigher excitations is described. The linear conductance attains the maximum\nvalue of $e^2/h$ only for the exact zero energy states. Also the differential\nconductance exhibits a complex pattern created by numerous crossings and\nanticrossings in the excitation spectrum. We reveal the crossings to be\nprotected by the inversion symmetry, while the anticrossings result from a\npairing-induced hybridization of particle-like and hole-like solutions with the\nsame inversion character. Our comprehensive treatment of the Kitaev chain\nallows us also to identify the contributions of both local and non-local\ntransmission processes to transport at arbitrary bias voltage. Local Andreev\nreflection processes dominate the transport within the bulk gap and diminish\nfor higher excited states, but reemerge when the bias voltage probes the\navoided crossings. The non-local direct transmission is enhanced above the bulk\ngap, but contributes also to the transport mediated by the topological states.",
        "positive": "Spin relaxation at the singlet-triplet crossing in a quantum dot: We study spin relaxation in a two-electron quantum dot in the vicinity of the\nsinglet-triplet crossing. The spin relaxation occurs due to a combined effect\nof the spin-orbit, Zeeman, and electron-phonon interactions. The\nsinglet-triplet relaxation rates exhibit strong variations as a function of the\nsinglet-triplet splitting. We show that the Coulomb interaction between the\nelectrons has two competing effects on the singlet-triplet spin relaxation. One\neffect is to enhance the relative strength of spin-orbit coupling in the\nquantum dot, resulting in larger spin-orbit splittings and thus in a stronger\ncoupling of spin to charge. The other effect is to make the charge density\nprofiles of the singlet and triplet look similar to each other, thus\ndiminishing the ability of charge environments to discriminate between singlet\nand triplet states. We thus find essentially different channels of\nsinglet-triplet relaxation for the case of strong and weak Coulomb interaction.\nFinally, for the linear in momentum Dresselhaus and Rashba spin-orbit\ninteractions, we calculate the singlet-triplet relaxation rates to leading\norder in the spin-orbit interaction, and find that they are proportional to the\nsecond power of the Zeeman energy, in agreement with recent experiments on\ntriplet-to-singlet relaxation in quantum dots."
    },
    {
        "anchor": "Pure spin currents in magnetically ordered insulator/normal metal\n  heterostructures: Pure spin currents, i.e. the transport of angular momentum without an\naccompanying charge current, represent a new, promising avenue in modern\nspintronics from both a fundamental and an application point of view. Such pure\nspin currents can not only flow in electrical conductors via mobile charge\ncarriers, but also in magnetically ordered electrical insulators as a flow of\nspin excitation quanta. Over the course of the last years remarkable results\nhave been obtained in heterostructures consisting of magnetically ordered\ninsulators interfaced with a normal metal, where a pure spin current flows\nacross the interface. This topical review article deals with the fundamental\nprinciples, experimental findings and recent developments in the field of pure\nspin currents in magnetically ordered insulators. We here put our focus onto\nfour different manifestations of pure spin currents in such heterostructures:\nThe spin pumping effect, the longitudinal spin Seebeck effect, the spin Hall\nmagnetoresistance and the all-electrical detection of magnon transport in\nnon-local device concepts. In this article, we utilize a common theoretical\nframework to explain all four effects and explain important material systems\n(especially rare-earth iron garnets) used in the experiments. For each effect\nwe introduce basic measurement techniques and detection schemes and discuss\ntheir application in the experiment. We account for the remarkable progress\nachieved in each field by reporting the recent progress in each field and by\ndiscussing research highlights obtained in our group. Finally, we conclude the\nreview article with an outlook on future challenges and obstacles in the field\nof pure spin currents in magnetically ordered insulator / normal metal\nheterostructures.",
        "positive": "The pulse and monochromatic light stimulation of semiconductor quantum\n  wells: The light reflectance and absorbance are calculated for a quantum well (QW)\nthe width of which is comparable with the light wave length. The difference of\nthe refraction coefficients of the quantum well and barriers is taken into\naccount. The stimulating pulse form is arbitrary. An existence of two closely\nsituated discrete excitation energy levels is supposed. Such energy level pare\nmay correspond to two magnetopolaron states in a quantizing magnetic field\nperpendicular to the QW plane. The relationship of the radiative and\nnon-radiative damping is arbitrary. The final results does not use the\napproximation of the weak Coulomb interaction of electrons and holes."
    },
    {
        "anchor": "High-Q optomechanical GaAs nanomembranes: We present a simple fabrication method for the realization of suspended GaAs\nnanomembranes for cavity quantum optomechanics experiments. GaAs nanomembranes\nwith an area of 1.36 mm by 1.91 mm and a thickness of 160 nm are obtained by\nusing a two-step selective wet-etching technique. The frequency noise spectrum\nreveals several mechanical modes in the kilohertz regime with mechanical\nQ-factors up to 2,300,000 at room temperature. The measured mechanical mode\nprofiles agree well with a taut rectangular drumhead model. Our results show\nthat GaAs nanomembranes provide a promising path towards quantum optical\ncontrol of massive nanomechanical systems.",
        "positive": "Formation of dark excitons in monolayer transition metal dichalcogenides\n  by a vortex beam: optical selection rules: Monolayer transition metal dichalcogenides host tightly-bound excitons, which\ndominate their optoelectronic response even at room temperatures. Light beams\nare often used to study these materials with the polarization - often termed as\nthe spin angular momentum of the light - providing the mechanism for exciting\nexcitonic states. Light beams, however, can also carry an orbital angular\nmomentum by creating helical structures of their phase front. In this work, we\nconsider a Laguerre-Gaussian beam possessing an orbital angular momentum in\naddition to the spin angular momentum to create excitons in monolayer\ntransition metal dichalcogenides. We derive optical selection rules that govern\nthe allowed transitions to various exciton series using symmetry arguments. Our\nsymmetry considerations show that we can create dark excitons using these\nhigh-order optical beams opening up new avenues for creating long-lived dark\nexcitons with the potential of exploiting them in quantum information\nprocessing and storage."
    },
    {
        "anchor": "Nonequilibrium transfer and decoherence in quantum impurity problems: Using detailed balance and scaling properties of integrals that appear in the\nCoulomb gas reformulation of quantum impurity problems, we establish exact\nrelations between the nonequilibrium transfer rates of the boundary sine-Gordon\nand the anisotropic Kondo model at zero temperature. Combining these results\nwith findings from the thermodynamic Bethe ansatz, we derive exact closed form\nexpressions for the transfer rate in the biased spin-boson model in the scaling\nlimit. They illustrate how the crossover from weak to strong tunneling takes\nplace. Using a conjectured correspondence between the transfer and the\ndecoherence rate, we also determine the exact lower bound for damping of the\ncoherent oscillation as a function of bias and dissipation strength in this\nparadigmic model for NMR and superposition of macroscopically distinct states\n(qubits).",
        "positive": "Multifractal analysis of the electronic states in the Fibonacci\n  superlattice under weak electric fields: Influence of the weak electric field on the electronic structure of the\nFibonacci superlattice is considered. The electric field produces a nonlinear\ndynamics of the energy spectrum of the aperiodic superlattice. Mechanism of the\nnonlinearity is explained in terms of energy levels anticrossings. The\nmultifractal formalism is applied to investigate the effect of weak electric\nfield on the statistical properties of electronic eigenfunctions. It is shown\nthat the applied electric field does not remove the multifractal character of\nthe electronic eigenfunctions, and that the singularity spectrum remains\nnon-parabolic, however with a modified shape. Changes of the distances between\nenergy levels of neighbouring eigenstates lead to the changes of the inverse\nparticipation ratio of the corresponding eigenfunctions in the weak electric\nfield. It is demonstrated, that the local minima of the inverse participation\nratio in the vicinity of the anticrossings correspond to discontinuity of the\nfirst derivative of the difference between marginal values of the singularity\nstrength. Analysis of the generalized dimension as a function of the electric\nfield shows that the electric field correlates spatial fluctuations of the\nneighbouring electronic eigenfunction amplitudes in the vicinity of\nanticrossings, and the nonlinear character of the scaling exponent confirms\nmultifractality of the corresponding electronic eigenfunctions."
    },
    {
        "anchor": "Giant ultra-broadband photoconductivity in twisted graphene\n  heterostructures: The requirements for broadband photodetection are becoming exceedingly\ndemanding in hyperspectral imaging. Whilst intrinsic photoconductor arrays\nbased on mercury cadmium telluride represent the most sensitive and suitable\ntechnology, their optical spectrum imposes a narrow spectral range with a sharp\nabsorption edge that cuts their operation to < 25 um. Here, we demonstrate a\ngiant ultra-broadband photoconductivity in twisted double bilayer graphene\nheterostructures spanning a spectral range of 2 - 100 um with internal quantum\nefficiencies ~ 40 % at speeds of 100 kHz. The giant response originates from\nunique properties of twist-decoupled heterostructures including pristine,\ncrystal field induced terahertz band gaps, parallel photoactive channels, and\nstrong photoconductivity enhancements caused by interlayer screening of\nelectronic interactions by respective layers acting as sub-atomic spaced\nproximity screening gates. Our work demonstrates a rare instance of an\nintrinsic infrared-terahertz photoconductor that is complementary\nmetal-oxide-semiconductor compatible and array integratable, and introduces\ntwist-decoupled graphene heterostructures as a viable route for engineering\ngapped graphene photodetectors with 3D scalability.",
        "positive": "Joule-assisted silicidation for short-channel silicon nanowire devices: We report on a technique enabling electrical control of the contact\nsilicidation process in silicon nanowire devices. Undoped silicon nanowires\nwere contacted by pairs of nickel electrodes and each contact was selectively\nsilicided by means of the Joule effect. By a realtime monitoring of the\nnanowire electrical resistance during the contact silicidation process we were\nable to fabricate nickel-silicide/silicon/nickel- silicide devices with\ncontrolled silicon channel length down to 8 nm."
    },
    {
        "anchor": "Tunable Topology and Berry Curvature Dipole in Transition Metal\n  Dichalcogenide Janus Monolayers: Janus transition metal dichalcogenides, with intrinsic mirror asymmetry,\nexhibit a wide array of interesting properties. In this work, we study Janus\nmonolayers derived from WTe$_2$ using first-principles and tight-binding\ncalculations. We discover that WSeTe and WSTe are topologically trivial, in\ncontrast to the parent quantum spin Hall insulator WTe$_2$. Motivated by the\ngrowing interest in non-linear Hall effect, which also requires asymmetric\nstructures, we investigate the Berry curvature and its dipole in these Janus\nsystems and find that they exhibit strikingly large values of Berry curvature\ndipole, despite being in the topologically trivial phase. We track down the\norigin of this behaviour and put forth a low-energy massive Dirac model to\nunderstand the central features of our ab initio computations. Our predictions\nintroduce Janus monolayers as promising new platforms for exploring as well as\nengineering non-linear Hall effect.",
        "positive": "Non-circular semiconductor nanorings of type I and II: Emission kinetics\n  in the exciton Aharonov-Bohm effect: Transition energies and oscillator strengths of excitons in dependence on\nmagnetic field are investigated in type I and II semiconductor nanorings. A\nslight deviation from circular (concentric) shape of the type II nanoring gives\na better observability of the Aharonov-Bohm oscillations since the ground state\nis always optically active. Kinetic equations for the exciton occupation are\nsolved with acoustic phonon scattering as the major relaxation process, and\nabsorption and luminescence spectra are calculated showing deviations from\nequilibrium. The presence of a non-radiative exciton decay leads to a quenching\nof the integrated photoluminescence with magnetic field."
    },
    {
        "anchor": "Spin states and persistent currents in a mesoscopic ring with an\n  embedded magnetic impurity: Spin states and persistent currents are investigated theoretically in a\nmesoscopic ring with an embedded magnetic ion under a uniform magnetic field\nincluding the spin-orbit interactions. The magnetic impurity acts as a\nspin-dependent $\\delta$-potential for electrons and results in gaps in the\nenergy spectrum, consequently suppresses the oscillation of the persistent\ncurrents. The competition between the Zeeman splittings and the $s$-$d$\nexchange interaction leads to a transition of the electron ground state in the\nring. The interplay between the periodic potential induced by the Rashba and\nDresselhaus spin-orbit interactions and the $\\delta$-potential induced by the\nmagnetic impurity leads to significant variation in the energy spectrum, charge\ndensity distribution, and persistent currents of electrons in the ring.",
        "positive": "Force sensitivity of multilayer graphene optomechanical devices: Mechanical resonators based on low-dimensional materials are promising for\nforce and mass sensing experiments. The force sensitivity in these ultra-light\nresonators is often limited by the imprecision in the measurement of the\nvibrations, the fluctuations of the mechanical resonant frequency, and the\nheating induced by the measurement. Here, we strongly couple multilayer\ngraphene resonators to superconducting cavities in order to achieve a\ndisplacement sensitivity of $1.3$ fm Hz$^{-1/2}$. This coupling also allows us\nto damp the resonator to an average phonon occupation of $7.2$. Our best force\nsensitivity, $390$ zN Hz$^{-1/2}$ with a bandwidth of $200$ Hz, is achieved by\nbalancing measurement imprecision, optomechanical damping, and heating. Our\nresults hold promise for studying the quantum capacitance of graphene, its\nmagnetization, and the electron and nuclear spins of molecules adsorbed on its\nsurface."
    },
    {
        "anchor": "Valley selecting current partition at zero-line mode of quantum\n  anomalous Hall topologies: Topologically protected zero-line modes appear at the interface between two\nregions of the monolayer graphene in quantum anomalous Hall phase with\ndifferent Chern number. In the presence of staggered sublattice potential, the\nband gaps of the two valleys become different, and the phase diagram defined by\nthe Chern number has an additional regime of topologically trivial phase. The\ninterface between the topologically trivial and non-trivial regions hosts\nzero-line mode in only one valley. By tuning the exchange field, three types of\ninterface that host zero-line modes in selected valley(s) are formed. The\nnano-devices consisted of Y-shape junctions of the three types of interface\nexhibit the functions of valley splitting, merging or filtering for the\nincident currents.",
        "positive": "Comparison of aluminum oxide empirical potentials from cluster to\n  nanoparticle: Aluminum oxide nanoparticles are increasingly sought in numerous\ntechnological applications. However, as the nanoparticles grow during the\nsynthesis, two phase transitions occur. At the nanoscale, numerical simulation\nof the stability of the alumina phases requires the use of empirical potentials\nthat are reliable over a large range of system sizes going from a few atoms to\nseveral hundred thousand atoms. In this work, we confronted four different\nempirical potentials that are currently employed for bulk alumina. We found\nthat only two of them are correct at the molecular level when compared to DFT\ncalculations. Furthermore, the two potentials remain the best at the nanoscale\nas they reproduce one or two phase transitions that were observed\nexperimentally: from amorphous solid to cubic crystal ({\\gamma}) and from cubic\nto hexagonal ({\\alpha}, i.e. corundum) crystal."
    },
    {
        "anchor": "Current Dependence of Spin Torque Switching Barrier: The current dependence of the switching barrier for spin torque switching of\nan in-plane magnetized ferromagnet was studied. Two scaling currents, I_{c}$\nand I_{c}^{*}(>I_{c}), were introduced to distinguish the magnetization\nstability. In the low-current region I<I_{c}, the switching barrier is linear\nto the current with another scaling current \\tilde{I}_{c}, while such linear\nscaling does not hold in the high-current region I_{c} < I < I_{c}^{*}. The\nlinear scaling is valid for the high temperature and the long current pulse\nduration time.",
        "positive": "Near-field thermal imaging of nanostructured surfaces: We show that a near-field scanning thermal microscope, which essentially\ndetects the local density of states of the thermally excited electromagnetic\nmodes at nanometer distances from some material, can be employed for nanoscale\nimaging of structures on that material's surface. This finding is explained\ntheoretically by an approach which treats the surface structure perturbatively."
    },
    {
        "anchor": "Fine structure of the local pseudogap and Fano effect for\n  superconducting electrons near a zigzag graphene edge: Motivated by recent scanning tunneling experiments on zigzag-terminated\ngraphene this paper investigates an interplay of evanescent and extended\nquasiparticle states in the local density of states (LDOS) near a zigzag edge\nusing the Green's function of the Dirac equation. A model system is considered\nwhere the local electronic structure near the edge influences transport of both\nnormal and superconducting electrons via a Fano resonance. In particular, the\ntemperature enhancement of the critical Josephson current and 0-pi transitions\nare predicted.",
        "positive": "Telegraph Noise and Fractional Statistics in the Quantum Hall Effect: We study theoretically nonequilibrium noise in the fractional quantum Hall\nregime for an Aharonov Bohm ring which has a third contact in the middle of the\nring. We show that as a consequence of their fractional statistics the\ntunneling of a Laughlin quasiparticle between the inner and outer edge of the\nring changes the effective Aharonov Bohm flux experienced by quasiparticles\ngoing around the ring, leading to a change in the conductance across the ring.\nA small current in the middle contact therefore gives rise to fluctuations in\nthe current flowing across the ring which resemble random telegraph noise. We\nanalyze this noise using the chiral Luttinger liquid model. At low frequencies\nthe telegraph noise varies inversely with the quasiparticle tunneling current,\nand can be much larger than the shot noise. We propose that combining the\nAharonov Bohm effect with a noise measurement provides a direct method for\nobserving fractional statistics."
    },
    {
        "anchor": "Radiation-induced magnetoresistance oscillations with massive Dirac\n  fermions: We report on a theoretical study on the rise of radiation-induced\nmagnetoresistance oscillations in two-dimensional systems of massive Dirac\nfermions. We study the bilayer system of monolayer graphene and hexagonal boron\nnitride (h-BN/graphene) and the trilayer system of hexagonal boron nitride\nencapsulated graphene (h-BN/graphene/h-BN). We extend the radiation-driven\nelectron orbit model that was previously devised to study the same oscillations\nin two-dimensional systems of Schr\\\"odinger electrons (GaAs/AlGaAS\nheterostructure) to the case of massive Dirac fermions. In the simulations we\nobtain clear oscillations for radiation frequencies in the terahertz and\nfar-infrared bands. %which contrasts with the two-dimensional Schrodinger\nelectrons case, %that are mainly sensitive to microwave frequencies. We\ninvestigate also the power and temperatures dependence. For the former we\nobtain similar results as for Schr\\\"odinger electrons and predict the rise of\nzero resistance states. For the latter we obtain a similar qualitatively\ndependence but quantitatively different when increasing temperature. While in\nGaAs the oscillations are wiped out in a few degrees, interestingly enough, for\nmassive Dirac fermions, we obtain observable oscillations for temperatures\nabove $100$ K and even at room temperature for the higher frequencies used in\nthe simulations.",
        "positive": "Top-gate defined double quantum dots in InAs nanowires: We present low temperature transport measurements on double quantum dots in\nInAs nanowires grown by metal-organic vapor phase epitaxy. Two dots in series\nare created by lithographically defined top-gates with a procedure involving no\nextra insulating layer. We demonstrate the full tunability from strong to weak\ncoupling between the dots. The quantum mechanical nature of the coupling leads\nto the formation of a molecular state extending over both dots. The excitation\nspectra of the individual dots are observable by their signatures in the\nnonlinear transport."
    },
    {
        "anchor": "Reply to Comment by Vanderbilt, Souza and Haldane: arXiv:1312.4200: We reassert our statement that the non-quantized Weyl node contribution to\nthe anomalous Hall conductivity is not a Fermi surface property, contrary to\nthe claim by Vanderbilt, Souza and Haldane.",
        "positive": "Tunneling of fluxons via a Josephson resonant level: Fluxons in a superconducting loop can be coherently coupled by quantum phase\nslips occurring at a weak link such as a Josephson junction. If Cooper pair\ntunneling at the junction occurs through a resonant level, $2\\pi$ quantum phase\nslips are suppressed, and fluxons are predominantly coupled by $4\\pi$ quantum\nphase slips. We analyze this scenario by computing the coupling between fluxons\nas the level is brought into resonance with the superconducting condensate. The\nresults indicate that the $4\\pi$-dominated regime can be observed directly in\nthe transition spectrum for circuit parameters typical of a fluxonium qubit. We\nalso show that, if the inductive energy of the loop is much smaller than the\nplasma frequency of the junction, the low-energy Hamiltonian of the circuit is\ndual to that of a topological superconducting island. These findings can inform\nexperiments on bifluxon qubits as well as the design of novel types of\nprotected qubits."
    },
    {
        "anchor": "Quantized conductance in an AlAs 2D electron system quantum point\n  contact: We report experimental results on a quantum point contact (QPC) device formed\nin a wide AlAs quantum well where the two-dimensional electrons occupy two\nin-plane valleys with elliptical Fermi contours. To probe the closely-spaced,\none-dimensional electric subbands, we fabricated a point contact device defined\nby shallow-etching and a top gate that covers the entire device. The\nconductance versus top gate bias trace shows a series of weak plateaus at\ninteger multiples of $2e^2/h$, indicating a broken valley degeneracy in the QPC\nand implying the potential use of QPC as a simple \"valley filter\" device. A\nmodel is presented to describe the quantized energy levels and the role of the\nin-plane valleys in the transport. We also observe a well-developed conductance\nplateau near $0.7x2e^2/h$ which may reflect the strong electron-electron\ninteraction in the system.",
        "positive": "Time-resolved Hall conductivity of pulse-driven topological quantum\n  systems: We address the question of how the time-resolved bulk Hall response of a two\ndimensional honeycomb lattice develops when driving the system with a pulsed\nperturbation. A simple toy model that switches a valley Hall signal by breaking\ninversion symmetry is studied in detail for slow quasi-adiabatic ramps and\nsudden quenches, obtaining an oscillating dynamical response that depends\nstrongly on doping and time-averaged values that are determined both by the out\nof equilibrium occupations and the Berry curvature of the final states. On the\nother hand, the effect of irradiating the sample with a circularly-polarized\ninfrared pump pulse that breaks time reversal symmetry and thus ramps the\nsystem into a non-trivial topological regime is probed. Even though there is a\nnon quantized average signal due to the break down of the Floquet adiabatical\npicture, some features of the photon-dressed topological bands are revealed to\nbe present even in a few femtosecond timescale. Small frequency oscillations\nduring the transient response evidence the emergence of dynamical Floquet gaps\nwhich are consistent with the instantaneous amplitude of the pump envelope. On\nthe other hand, a characteristic heterodyining effect is manifested in the\nmodel. The presence of a remnant Hall response for ultra-short pulses that\ncontain only a few cycles of the radiation field is briefly discussed."
    },
    {
        "anchor": "Large-area nanoengineering of graphene corrugations for\n  visible-frequency graphene plasmons: Quantum confinement of graphene carriers is an effective way to engineer its\nproperties. It is commonly realized through physical edges that are associated\nwith the deterioration of mobility and strong suppression of plasmon\nresonances. Here, we demonstrate a simple, large-area, edge-free\nnanostructuring technique, based on amplifying random nanoscale structural\ncorrugations to a level where they efficiently confine carriers, without\ninducing significant inter-valley scattering. This soft confinement, allows the\nlow-loss lateral ultra-confinement of graphene plasmons, scaling up their\nresonance frequency from native terahertz to commercially relevant visible\nrange. Visible graphene plasmons localized into nanocorrugations mediate\nseveral orders of magnitude stronger light-matter interactions (Raman\nenhancement) than those previously achieved with graphene, enabling the\ndetection of specific molecules from femtomolar solutions or ambient air.\nMoreover, nanocorrugated graphene sheets also support propagating visible\nplasmon modes revealed by scanning near-field optical microscopy observation of\ntheir interference patterns.",
        "positive": "Magnetohydrodynamics and electro-electron interaction of massless Dirac\n  fermions: The magnetotransport properties of massless Dirac fermions in a gapless HgTe\nquantum well are investigated. In samples with narrow channels, a large\nnegative magnetoresistance with a Lorentzian profile is observed, which is\ninterpreted as a manifestation of electron viscosity due to electron-electron\ninteraction. Comparison of experiment with theory yields the shear stress\nrelaxation time of the Dirac fermions caused by electron-electron scattering."
    },
    {
        "anchor": "Thermal Transport in Twisted Bilayer Graphene: An Equilibrium Molecular\n  Dynamics Study: Twisted bilayer graphene (tBLG) is two graphene layers placed on top of each\nother with a twist angle, making it has tunable thermal properties. In this\npaper, we report an analysis of thermal conductivity ($\\kappa$), phonon density\nof states, and specific heat capacity of tBLG with various twist angles over a\nrange of temperatures using equilibrium molecular dynamics simulations based on\nthe Green-Kubo method. Simulation shows that stacking and twisting graphene\nlayers lead to a decrease in the thermal conductivity, with the highest\n$\\kappa$ at around room temperature owned by the tBLG with a twist angle of\n3.89$^{\\circ}$ followed by 16.43$^{\\circ}$ and 4.41$^{\\circ}$. We also perform\nquantum correction to the simulation results to show the process of increasing\nthermal conductivity at low temperatures.",
        "positive": "Quantum computing with spin cluster qubits: We study the low energy states of finite spin chains with isotropic\n(Heisenberg) and anisotropic (XY and Ising-like) exchange interaction with\nuniform and non-uniform coupling constants. We show that for an odd number of\nsites a spin cluster qubit can be defined in terms of the ground state doublet.\nThis qubit is remarkably insensitive to the placement and coupling anisotropy\nof spins within the cluster. One- and two-qubit quantum gates can be generated\nby magnetic fields and inter-cluster exchange, and leakage during quantum gate\noperation is small. Spin cluster qubits inherit the long decoherence times and\nshort gate operation times of single spins. Control of single spins is hence\nnot necessary for the realization of universal quantum gates."
    },
    {
        "anchor": "Quantum valley Hall effect, orbital magnetism, and anomalous Hall effect\n  in twisted multilayer graphene systems: We study the electronic structures and topological properties of\n$(M+N)$-layer twisted graphene systems. We consider the generic situation that\n$N$-layer graphene is placed on top of the other $M$-layer graphene, and is\ntwisted with respect to each other by an angle $\\theta$. In such twisted\nmultilayer graphene (TMG) systems, we find that there exists two low-energy\nflat bands for each valley emerging from the interface between the $M$ layers\nand the $N$ layers. These two low-energy bands in the TMG system possess valley\nChern numbers that are dependent on both the number of layers and the stacking\nchiralities. In particular, when the stacking chiralities of the $M$ layers and\n$N$ layers are opposite, the total Chern number of the two low-energy bands for\neach valley equals to $\\pm(M+N-2)$ (per spin). If the stacking chiralities of\nthe $M$ layers and the $N$ layers are the same, then the total Chern number of\nthe two low-energy bands for each valley is $\\pm(M-N)$ (per spin). The valley\nChern numbers of the low-energy bands are associated with large,\nvalley-contrasting orbital magnetizations, suggesting the possible existence of\norbital ferromagnetism and anomalous Hall effect once the valley degeneracy is\nlifted either externally by a weak magnetic field or internally by Coulomb\ninteraction through spontaneous symmetry breaking.",
        "positive": "Relaxation and frequency shifts induced by quasiparticles in\n  superconducting qubits: As low-loss non-linear elements, Josephson junctions are the building blocks\nof superconducting qubits. The interaction of the qubit degree of freedom with\nthe quasiparticles tunneling through the junction represent an intrinsic\nrelaxation mechanism. We develop a general theory for the qubit decay rate\ninduced by quasiparticles, and we study its dependence on the magnetic flux\nused to tune the qubit properties in devices such as the phase and flux qubits,\nthe split transmon, and the fluxonium. Our estimates for the decay rate apply\nto both thermal equilibrium and non-equilibrium quasiparticles. We propose\nmeasuring the rate in a split transmon to obtain information on the possible\nnon-equilibrium quasiparticle distribution. We also derive expressions for the\nshift in qubit frequency in the presence of quasiparticles."
    },
    {
        "anchor": "Gate Tunable Quantum Oscillations in Air-Stable and High Mobility\n  Few-Layer Phosphorene Heterostructures: As the only non-carbon elemental layered allotrope, few-layer black\nphosphorus or phosphorene has emerged as a novel two-dimensional (2D)\nsemiconductor with both high bulk mobility and a band gap. Here we report\nfabrication and transport measurements of phosphorene-hexagonal BN (hBN)\nheterostructures with one-dimensional (1D) edge contacts. These transistors are\nstable in ambient conditions for >300 hours, and display ambipolar behavior, a\ngate-dependent metal-insulator transition, and mobility up to 4000 $cm^2$/Vs.\nAt low temperatures, we observe gate-tunable Shubnikov de Haas (SdH)\nmagneto-oscillations and Zeeman splitting in magnetic field with an estimated\ng-factor ~2. The cyclotron mass of few-layer phosphorene holes is determined to\nincrease from 0.25 to 0.31 $m_e$ as the Fermi level moves towards the valence\nband edge. Our results underscore the potential of few-layer phosphorene (FLP)\nas both a platform for novel 2D physics and an electronic material for\nsemiconductor applications.",
        "positive": "Fractional Quantum Hall plateaus in mosaic-like conductors: We report a simple route to generate magnetotransport data that results in\nfractional quantum Hall plateaus in the conductance. Ingredients to the\ngenerating model are conducting tiles with integer quantum Hall effect and\nmetallic linkers, further Kirchhoff rules. When connecting few identical tiles\nin a mosaic, fractional steps occur in the conductance values. Richer spectra\nrepresenting several fractions occur when the tiles are parametrically varied.\nParts of the simulation data are supported with purposefully designed graphene\nmosaics in high magnetic fields. The findings emphasize that the occurrence of\nfractional conductance values, in particular in two-terminal measurements, does\nnot necessarily indicate interaction-driven physics. We underscore the\nimportance of an independent determination of charge densities and critically\ndiscuss similarities with and differences to the fractional quantum Hall\neffect."
    },
    {
        "anchor": "Enhanced light-matter interaction in graphene-covered gold nanovoid\n  arrays: The combination of graphene with noble-metal nanostructures is currently\nbeing explored for strong light-graphene interaction enhanced by plasmons. We\nintroduce a novel hybrid graphene-metal system for studying light-matter\ninteractions with gold-void nanostructures exhibiting resonances in the visible\nrange. Strong coupling of graphene layers to the plasmon modes of the nanovoid\narrays results in significant frequency shifts of the underlying plasmon\nresonances, enabling more than 30% absolute light absorption in a single layer\nof graphene and up to 700-fold enhancement of the Raman response of the\ngraphene. These new perspectives enable us to verify the presence of graphene\non gold-void arrays and the enhancement even allows us to accurately quantify\nthe number of layers. Experimental observations are further supported by\nnumerical simulations and perturbation-theory analysis. The graphene gold-void\nplatform is beneficial for sensing of molecules and placing R6G dye molecules\non top of the graphene, we observe a strong enhancement of the R6G Raman\nfingerprints. These results pave the way toward advanced substrates for\nsurface-enhanced Raman scattering (SERS) with potential for unambiguous\nsingle-molecule detection on the atomically well-defined layer of graphene.",
        "positive": "Towards an experimental proof of superhydrophobicity enhanced by quantum\n  fluctuations freezing on a broadband-absorber metamaterial: Previous theoretical works suggested that superhydrophobicity could be\nenhanced through partial inhibition of the quantum vacuum modes at the surface\nof a broadband-absorber metamaterial which acts in the extreme ultraviolet\nfrequency domain. This effect would then compete with the classical\nCassie-Baxter interpretation of superhydrophobicity. In this article, we first\ntheoretically establish the expected phenomenological features related to such\na kind of \"quantum\" superhydrophobicity. Then, relying on this theoretical\nframework, we experimentally study patterned silicon surfaces on which\norganosilane molecules were grafted, all the coated surfaces having similar\ncharacteristic pattern sizes but different profiles. Some of these surfaces can\nindeed freeze quantum photon modes while others cannot. While the latter ones\nallow hydrophobicity, only the former ones allow for superhydrophobicity. We\nbelieve these results lay the groundwork for further complete assessment of\nsuperhydrophobicity induced by quantum fluctuations freezing."
    },
    {
        "anchor": "Conductance quantization and snake states in graphene magnetic\n  waveguides: We consider electron waveguides (quantum wires) in graphene created by\nsuitable inhomogeneous magnetic fields. The properties of uni-directional snake\nstates are discussed. For a certain magnetic field profile, two spatially\nseparated counter-propagating snake states are formed, leading to conductance\nquantization insensitive to backscattering by impurities or irregularities of\nthe magnetic field.",
        "positive": "Effects of dissipation on quantum phase transitions: We discuss the effect of dissipation on quantum phase transitions. In\nparticular we concentrate on the Superconductor to Insulator and Quantum-Hall\nto Insulator transitions. By invoking a phenomenological parameter $\\alpha$ to\ndescribe the coupling of the system to a continuum of degrees of freedom\nrepresenting the dissipative bath, we obtain new phase diagrams for the quantum\nHall and superconductor-insulator problems. Our main result is that, in\ntwo-dimensions, the metallic phases observed in finite magnetic fields\n(possibly also strictly zero field) are adiabatically deformable from one to\nthe other. This is plausible, as there is no broken symmetry which\ndifferentiates them."
    },
    {
        "anchor": "Thermodefect voltage in graphene nanoribbon junctions: Thermoelectric junctions are often made of components of different materials\ncharacterized by distinct transport properties. Single material junctions, with\nthe same type of charge carriers, have also been considered to investigate\nvarious classical and quantum effects on the thermoelectric properties of\nnanostructured materials. We here introduce the concept of defect-induced\nthermoelectric voltage, namely, {\\it thermodefect voltage}, in graphene\nnanoribbon (GNR) junctions under a temperature gradient. Our thermodefect\njunction is formed by two GNRs with identical properties except the existence\nof defects in one of the nanoribbons. At room temperature the thermodefect\nvoltage is highly sensitive to the types of defects, their locations, as well\nas the width and edge configurations of the GNRs. We demonstrate that the\nthermodefect voltage can be as high as $1.7\\,$mV/K for $555$-$777$ defects in\nsemiconducting armchair GNRs. We further investigate the Seebeck coefficient,\nelectrical conductance, and electronic thermal conductance, and also the power\nfactor of the individual junction components to explain the thermodefect\neffect. Taken together, our study presents a new pathway to enhance the\nthermoelectric properties of nanomaterials.",
        "positive": "Artificial heavy fermions in a van der Waals heterostructure: Heavy fermion systems represent one of the paradigmatic strongly correlated\nstates of matter. They have been used as a platform for investigating exotic\nbehavior ranging from quantum criticality and non-Fermi liquid behavior to\nunconventional topological superconductivity. Heavy fermions arise from the\nexchange interaction between localized magnetic moments and conduction\nelectrons that leads to the well-known Kondo effect. In a Kondo lattice, the\ninteraction between the localized moments gives rise to a band with heavy\neffective mass. This intriguing phenomenology has so far only been realized in\ncompounds containing rare-earth elements with 4f or 5f electrons. Here, we\nrealize a designer van der Waals heterostructure where artificial heavy\nfermions emerge from the Kondo coupling between a lattice of localized magnetic\nmoments and itinerant electrons in a 1T/1H-TaS$_2$ heterostructure. We study\nthe heterostructure using scanning tunneling microscopy (STM) and spectroscopy\n(STS) and show that depending on the stacking order of the monolayers, we can\neither reveal the localized magnetic moments and the associated Kondo effect,\nor the conduction electrons with a heavy-fermion hybridization gap. Our\nexperiments realize an ultimately tuneable platform for future experiments\nprobing enhanced many-body correlations, dimensional tuning of quantum\ncriticality, and unconventional superconductivity in two-dimensional artificial\nheavy-fermion systems."
    },
    {
        "anchor": "Theory of Friedel oscillations in monolayer graphene and group-VI\n  dichalcogenides in a magnetic field: Friedel oscillations (FO) of electron density caused by a delta-like neutral\nimpurity in two-dimensional (2D) systems in a magnetic field are calculated.\nThree 2D cases are considered: free electron gas, monolayer graphene and\ngroup-VI dichalcogenides. An exact form of the renormalized Green's function is\nused in the calculations, as obtained by a summation of the infinite Dyson\nseries and regularization procedure. Final results are valid for large ranges\nof potential strengths $V_0$, electron densities $n_e$, magnetic fields $B$ and\ndistances from the impurity $r$. Realistic models for the impurities are used.\nThe first FO of induced density in WS$_2$ are described by the relation $\\Delta\nn(\\vec{r}) \\propto \\sin(2\\pi r/T_{FO})/r^2$, where $T_{FO} \\propto\n1/\\sqrt{E_F}$. For weak impurity potentials, the amplitudes of FO are\nproportional to $V_0$. For attractive potentials and high fields the total\nelectron density remains positive for all $r$. On the other hand, for low\nfields, repulsive potentials and small $r$, the total electron density may\nbecome negative, so that many-body effects should be taken into account.",
        "positive": "Thermoelectricity by Perfectly Conducting Channels in Quantum Spin Hall\n  Systems: Thermoelectric transport of two-dimensional quantum spin Hall systems are\ntheoretically studied in narrow ribbon geometry. We find that at high\ntemperature electrons in the bulk states dominate. By lowering temperature, the\n\"perfectly conducting\" edge channels becomes dominant, and a bulk-to-edge\ncrossover occurs. Correspondingly, by lowering temperature, the figure of merit\nfirst decreases and then will increase again due to edge-state-dominated\nthermoelectric transport."
    },
    {
        "anchor": "Spin Texture and Mirror Chern number in Hg-Based Chalcogenides: The unique feature of surface states in topological insulators is the\nso-called \"spin-momentum locking\", which means that electron spin is oriented\nalong a fixed direction for a given momentum and forms a texture in the\nmomentum space. In this work, we study spin textures of two typical topological\ninsulators in Hg-Based Chalcogenides, namely HgTe and HgS, based on both the\nfirst principles calculation and the eight band Kane model. We find opposite\nhelicities of spin textures between these two materials, originating from the\nopposite signs of spin-orbit couplings. Furthermore, we reveal that different\nmirror Chern numbers between HgTe and HgS characterize different topological\nnatures of the systems with opposite spin textures and guarantee the existence\nof gapless interface states.",
        "positive": "Abnormal anti-crossing effect in photon-magnon coupling: We report the experimental demonstration of an abnormal, opposite\nanti-crossing effect in a photon-magnon-coupled system that consists of an\nYttrium Iron Garnet film and an inverted pattern of split-ring resonator\nstructure (noted as ISRR) in a planar geometry. It is found that the normal\nshape of anti-crossing dispersion typically observed in photon-magnon coupling\nis changed to its opposite anti-crossing shape just by changing the\nposition/orientation of the ISRR's split gap with respect to the microstrip\nline axis along which ac microwave currents are applied. Characteristic\nfeatures of the opposite anti-crossing dispersion and its linewidth evolution\nare analyzed with the help of analytical derivations based on electromagnetic\ninteractions. The observed opposite anti-crossing dispersion is ascribed to the\ncompensation of both intrinsic damping and coupling-induced damping in the\nmagnon modes. This compensation is achievable by controlling the relative\nstrength and phase of oscillating magnetic fields generated from the ISRR's\nsplit gap and the microstrip feeding line. The position/orientation of an\nISRR's split gap provides a robust means of controlling the dispersion shape of\nanti-crossing and its damping in a photon-magnon coupling, thereby offering\nmore opportunity for advanced designs of microwave devices."
    },
    {
        "anchor": "Infrared nanoscopy of Dirac plasmons at the graphene-SiO2 interface: We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac\nfermions in graphene. This is achieved by confining mid-IR radiation at the\napex of a nanoscale tip: an approach yielding two orders of magnitude increase\nin the value of in-plane component of incident wavevector q compared to free\nspace propagation. At these high wavevectors, the Dirac plasmon is found to\ndramatically enhance the near-field interaction with mid-IR surface phonons of\nSiO2 substrate. Our data augmented by detailed modeling establish graphene as a\nnew medium supporting plasmonic effects that can be controlled by gate voltage.",
        "positive": "Pure spin current transport in a SiGe alloy: Using four-terminal nonlocal magnetoresistance measurements in lateral\nspin-valve devices with Si$_{\\rm 0.1}$Ge$_{\\rm 0.9}$, we study pure spin\ncurrent transport in a degenerate SiGe alloy ($n \\sim$ 5.0 $\\times$ 10$^{18}$\ncm$^{-3}$). Clear nonlocal spin-valve signals and Hanle-effect curves,\nindicating generation, manipulation, and detection of pure spin currents, are\nobserved. The spin diffusion length and spin lifetime of the Si$_{\\rm\n0.1}$Ge$_{\\rm 0.9}$ layer at low temperatures are reliably estimated to be\n$\\sim$ 0.5 $\\mu$m and $\\sim$ 0.2 ns, respectively. This study demonstrates the\npossibility of exploring physics and developing spintronic applications using\nSiGe alloys."
    },
    {
        "anchor": "Nb/InAs nanowire proximity junctions from Josephson to quantum dot\n  regimes: The superconducting proximity effect is probed experimentally in Josephson\njunctions fabricated with InAs nanowires contacted by Nb leads. Contact\ntransparencies $t \\sim 0.7$ are observed. The electronic phase coherence length\nat low temperatures exceeds the channel length. However, the elastic scattering\nlength is a few times shorter than the channel length. Electrical measurements\nreveal two regimes of quantum transport: (i) the Josephson regime,\ncharacterized by a dissipationless current up to $\\sim 100$ nA, and (ii) the\nquantum dot regime, characterized by the formation of Andreev Bound States\n(ABS) associated with spontaneous quantum dots inside the nanowire channel. In\nregime (i), the behaviour of the critical current $I_c$ versus an axial\nmagnetic field $B_{||}$ shows an unexpected modulation and persistence to\nfields $>2$ T. In the quantum dot regime, the ABS are modelled as the\ncurrent-biased solutions of an Anderson-type model. The applicability of\ndevices in both transport regimes to Majorana fermion experiments is discussed.",
        "positive": "Negative nonlocal resistance in mesoscopic gold Hall bars: Absence of\n  giant spin Hall effect: We report the observation of negative nonlocal resistances in multiterminal\nmesoscopic gold Hall bar structures whose characteristic dimensions are larger\nthan the electron mean-free path. Our results can only be partially explained\nby a classical diffusive model of the nonlocal transport, and are not\nconsistent with a recently proposed model based on spin Hall effects. Instead,\nour analysis suggests that a quasiballistic transport mechanism is responsible\nfor the observed negative nonlocal resistance. Based on the sensitivity of our\nmeasurements and the spin Hall effect model, we find an upper limit for the\nspin Hall angle in gold of 0.022 at 4.5 K."
    },
    {
        "anchor": "Local Fluctuations in Cavity Control of Ferroelectricity: Control of quantum matter through resonant electromagnetic cavities is a\npromising route towards establishing control over material phases and\nfunctionalities. Quantum paraelectric insulators -- materials which are nearly\nferroelectric -- are particularly promising candidate systems for this purpose\nsince they have strongly fluctuating collective modes which directly couple to\nthe electric field. In this work we explore this possibility in a system\ncomprised of a quantum paraelectric sandwiched between two high-quality metal\nmirrors, realizing a Fabry-Perot type cavity. By developing a full multimode,\ncontinuum description we are able to study the effect of the cavity in a\nspatially resolved way for a variety of system sizes and temperatures.\nSurprisingly, we find that once a continuum of transverse modes are included\nthe cavity ends up suppressing ferroelectric correlations. This effect arises\nfrom the screening out of transverse photons at the cavity boundaries and as a\nresult is confined to the surface of the paraelectric sample. We also explore\nthe temperature dependence of this effect and find it vanishes at high\ntemperatures, indicating it is a purely quantum mechanical effect. We connect\nour result to calculations of Casimir and Van der Waals forces, which we argue\nare closely related to the dipolar fluctuations in the quantum paraelectric.\nOur results are based on a general formalism and are expected to be widely\napplicable, paving the way towards studies of the quantum electrodynamics of\nheterostructures featuring multiple materials and phases.",
        "positive": "Spin-dependent pump current and noise in an adiabatic quantum pump based\n  on domain walls in a magnetic nanowire: We study the pump current and noise properties in an adiabatically modulated\nmagnetic nanowire with double domain walls (DW). The modulation is brought\nabout by applying a slowly oscillating magnetic and electric fields with a\ncontrollable phase difference. The pumping mechanism resembles the case of the\nquantum dot pump with two-oscillating gates. The pump current, shot noise, and\nheat flow show peaks when the Fermi energy matches with the spin-split resonant\nlevels localized between the DWs. The peak height of the pump current is an\nindicator for the lifetime of the spin-split quasistationary states between the\nDWs. For sharp DWs, the energy absorption from the oscillating fields results\nin side-band formations observable in the pump current. The pump noise carries\ninformation on the correlation properties between the nonequilibrium electrons\nand the quasi-holes created by the oscillating scatterer. The ratio between the\npump shot noise and the heat flow serves as an indicator for quasi-particle\ncorrelation."
    },
    {
        "anchor": "Stability of trions in strongly spin-polarized two-dimensional electron\n  gases: Low-temperature magneto-photoluminescence studies of negatively charged\nexcitons (X- trions) are reported for n-type modulation-doped ZnSe/Zn(Cd,Mn)Se\nquantum wells over a wide range of Fermi energy and spin-splitting. The\nmagnetic composition is chosen such that these magnetic two-dimensional\nelectron gases (2DEGs) are highly spin-polarized even at low magnetic fields,\nthroughout the entire range of electron densities studied (5e10 to 6.5e11\ncm^-2). This spin polarization has a pronounced effect on the formation and\nenergy of X-, with the striking result that the trion ionization energy (the\nenergy separating X- from the neutral exciton) follows the temperature- and\nmagnetic field-tunable Fermi energy. The large Zeeman energy destabilizes X- at\nthe nu=1 quantum limit, beyond which a new PL peak appears and persists to 60\nTesla, suggesting the formation of spin-triplet charged excitons.",
        "positive": "A microwave realization of the chiral orthogonal, unitary, and\n  symplectic ensembles: Random matrix theory has proven very successful in the understanding of the\nspectra of chaotic systems. Depending on symmetry with respect to time reversal\nand the presence or absence of a spin 1/2 there are three ensembles, the\nGaussian orthogonal (GOE), Gaussian unitary (GUE), and Gaussian symplectic\n(GSE) one. With a further particle-antiparticle symmetry the chiral variants of\nthese ensembles, the chiral orthogonal, unitary, and symplectic ensembles (the\nBDI, AIII, and CII in Cartan's notation) appear. A microwave study of the\nchiral ensembles is presented using a linear chain of evanescently coupled\ndielectric cylindrical resonators. In all cases the predicted repulsion\nbehavior between positive and negative eigenvalues for energies close to zero\ncould be verified."
    },
    {
        "anchor": "Impact of surface anisotropy on the spin-wave dynamics in thin\n  ferromagnetic film: The spin-wave dynamics in the thin CoFeB film in Damon-Eshbach geometry are\nstudied in three cases of boundary conditions -- free boundary conditions,\nsymmetrical surface anisotropy, and one-sided surface anisotropy. The\nanalytical model created by Wolfram and De Wames was extended to include\nperpendicular surface anisotropy in boundary conditions. Its comparison with\nnumerical simulations demonstrate perfect agreement between the approaches. The\nanalysis of the dispersion relation indicates that the presence of surface\nanisotropy increases the avoided crossing size between Damon-Eshbach mode and\nperpendicular standing modes. Additionally, asymmetrical one-sided surface\nanisotropy induces nonreciprocity in the dispersion relation. In-depth analysis\nof the avoided crossing size is conducted for systems with different boundary\nconditions, different thicknesses, surface anisotropy constant values, and\nexternal magnetic fields. It shows the significant role of the strength of\nsurface localization of Damon-Eshbach mode and the symmetry of perpendicular\nstanding modes in the avoided crossing broadening. Interestingly, for specific\nset of parameters the interaction between the particular modes can be\nsuppressed, resulting in a mode crossing. Such a crossing, which occurs only on\none side of the dispersion relation in a one-sided surface anisotropy system,\ncan be utilized in nonreciprocal devices.",
        "positive": "Shell Filling and Trigonal Warping in Graphene Quantum Dots: Transport measurements through a few-electron circular quantum dot in bilayer\ngraphene display bunching of the conductance resonances in groups of four,\neight and twelve. This is in accordance with the spin and valley degeneracies\nin bilayer graphene and an additional threefold 'minivalley degeneracy' caused\nby trigonal warping. For small electron numbers, implying a small dot size and\na small displacement field, a two-dimensional s- and then a p-shell are\nsuccessively filled with four and eight electrons, respectively. For electron\nnumbers larger than twelve, as the dot size and the displacement field\nincrease, the single-particle ground state evolves into a three-fold degenerate\nminivalley ground state. A transition between these regimes is observed in our\nmeasurements and can be described by band-structure calculations. Measurements\nin magnetic field confirm Hund's second rule for spin filling of the quantum\ndot levels, emphasizing the importance of exchange interaction effects."
    },
    {
        "anchor": "A multilayer multiconfiguration time-dependent Hartree study of the\n  nonequilibrium Anderson impurity model at zero temperature: Quantum transport is studied for the nonequilibrium Anderson impurity model\nat zero temperature employing the multilayer multiconfiguration time-dependent\nHartree theory within the second quantization representation (ML-MCTDH-SQR) of\nFock space. To adress both linear and nonlinear conductance in the Kondo\nregime, two new techniques of the ML-MCTDH-SQR simulation methodology are\nintroduced: (i) the use of correlated initial states, which is achieved by\nimaginary time propagation of the overall Hamiltonian at zero voltage and (ii)\nthe adoption of the logarithmic discretization of the electronic continuum.\nEmploying the improved methodology, the signature of the Kondo effect is\nanalyzed.",
        "positive": "Broadband enhancement of second harmonic generation at the domain walls\n  of magnetic topological insulators: We show that the second harmonic generation (SHG) is enhanced in the chiral\none-dimensional electron currents in a broad frequency range. The origin of the\nenhancement is two-fold: first, the linear dispersion of the current and the\nassociated plasmonic mode as well as the quasi-linear dispersion of\nplasmon-polariton result in the lift of the phase matching condition. Moreover,\nthe strong field localization leads to the further increase of the SHG in the\nstructure. The results suggest that the chiral currents localized at the domain\nwalls of magnetic topological insulators can be an efficient source of second\nharmonic signal in the terahertz frequency range."
    },
    {
        "anchor": "Manipulating Topological Valley Modes in Plasmonic Metasurfaces: The coupled light-matter modes supported by plasmonic metasurfaces can be\ncombined with topological principles to yield subwavelength topological valley\nstates of light. We give a systematic presentation of the topological valley\nstates available for lattices of metallic nanoparticles: All possible lattices\nwith hexagonal symmetry are considered, as well as valley states emerging on a\nsquare lattice. Several unique effects which have yet to be explored in\nplasmonics are identified, such as robust guiding, filtering and splitting of\nmodes, as well as dual-band effects. We demonstrate these by means of\nscattering computations based on the coupled dipole method that encompass the\nfull electromagnetic interactions between nanoparticles.",
        "positive": "Field theoretic study of electron-electron interaction effects in Dirac\n  liquids: The aim of this habilitation thesis is to present recent results, obtained\nduring the period 2012-2017, related to interaction effects in condensed matter\nphysics systems such as planar Dirac liquids, e.g., graphene and graphene-like\nsystems, the surface states of some topological insulators and possibly\nhalf-filled fractional quantum Hall systems (for their Dirac composite\nfermions). These liquids are characterized by gapless bands, strong\nelectron-electron interactions and emergent Lorentz invariance deep in the\ninfra-red. We address a number of important issues raised by experiments on\nthese systems covering subjects of wide current interest in low-energy\n(condensed matter) as well as high-energy (particle) physics. We shall consider\nin particular the subtle influence of interactions on transport properties and\ntheir supposedly crucial influence on a potential dynamical mass generation.\nThe resolution of these problems will guide us from the thorough examination of\nthe perturbative structure of gauge field theories to the development and\napplication of non-perturbative approaches known from quantum\nelectro/chromo-dynamics to address strong coupling issues."
    },
    {
        "anchor": "Magnonic Su-Schrieffer-Heeger Model in Honeycomb Ferromagnets: Topological electronics has extended its richness to non-electronic systems\nwhere phonons and magnons can play the role of electrons. In particular,\ntopological phases of magnons can be enabled by the Dzyaloshinskii-Moriya\ninteraction (DMI) which acts as an effective spin-orbit coupling. We show that\nbesides DMI, an alternating arrangement of Heisenberg exchange interactions\ncritically determines the magnon band topology, realizing a magnonic analog of\nthe Su-Schrieffer-Heeger model. On a honeycomb ferromagnet with perpendicular\nanisotropy, we calculate the topological phase diagram, the chiral edge states,\nand the associated magnon Hall effect by allowing the relative strength of\nexchange interactions on different links to be tunable. Including weak\nphonon-magnon hybridization does not change the result. Candidate materials are\ndiscussed.",
        "positive": "Depletion-mode Quantum Dots in Intrinsic Silicon: We report the fabrication and electrical characterization of depletion-mode\nquantum dots in a two-dimensional hole gas (2DHG) in intrinsic silicon. We use\nfixed charge in a SiO$_2$/Al$_2$O$_3$ dielectric stack to induce a 2DHG at the\nSi/SiO$_2$ interface. Fabrication of the gate structures is accomplished with a\nsingle layer metallization process. Transport spectroscopy reveals regular\nCoulomb oscillations with charging energies of 10-15 meV and 3-5 meV for the\nfew- and many-hole regimes, respectively. This depletion-mode design avoids\ncomplex multilayer architectures requiring precision alignment, and allows to\nadopt directly best practices already developed for depletion dots in other\nmaterial systems. We also demonstrate a method to deactivate fixed charge in\nthe SiO$_2$/Al$_2$O$_3$ dielectric stack using deep ultraviolet light, which\nmay become an important procedure to avoid unwanted 2DHG build-up in Si MOS\nquantum bits."
    },
    {
        "anchor": "Theory of Current and Shot Noise Spectroscopy in Single-Molecular\n  Quantum Dots with Phonon Mode: Using the Keldysh nonequilibrium Green function technique, we study the\ncurrent and shot noise spectroscopy of a single molecular quantum dot coupled\nto a local phonon mode. It is found that in the presence of electron-phonon\ncoupling, in addition to the resonant peak associated with the single level of\nthe dot, satellite peaks with the separation set by the frequency of phonon\nmode appear in the differential conductance. In the ``single level'' resonant\ntunneling region, the differential shot noise power exhibit two split peaks.\nHowever, only single peaks show up in the ``phonon assisted''\nresonant-tunneling region. An experimental setup to test these predictions is\nalso proposed.",
        "positive": "Dynamics and Control of Edge States in Laser-driven Graphene Nanoribbons: An intense laser field in the high-frequency regime drives carriers in\ngraphene nanoribbons (GNRs) out of equilibrium and creates\ntopologically-protected edge states. Using Floquet theory on driven GNRs, we\ncalculate the time evolution of local excitations of these edge states and show\nthat they exhibit a robust dynamics also in the presence of very localized\nlattice defects (atomic vacancies), which is characteristic of topologically\nnon-trivial behavior. We show how it is possible to control them by a modulated\nelectrostatic potential: They can be fully transmitted on the same edge,\nreflected on the opposite one, or can be split between the two edges, in\nanalogy with Hall edge states, making them promising candidates for\nflying-qubit architectures."
    },
    {
        "anchor": "A Crossbar Network for Silicon Quantum Dot Qubits: The spin states of single electrons in gate-defined quantum dots satisfy\ncrucial requirements for a practical quantum computer. These include extremely\nlong coherence times, high-fidelity quantum operation, and the ability to\nshuttle electrons as a mechanism for on-chip flying qubits. In order to\nincrease the number of qubits to the thousands or millions of qubits needed for\npractical quantum information we present an architecture based on shared\ncontrol and a scalable number of lines. Crucially, the control lines define the\nqubit grid, such that no local components are required. Our design enables\nqubit coupling beyond nearest neighbors, providing prospects for non-planar\nquantum error correction protocols. Fabrication is based on a three-layer\ndesign to define qubit and tunnel barrier gates. We show that a double\nstripline on top of the structure can drive high-fidelity single-qubit\nrotations. Qubit addressability and readout are enabled by self-aligned\ninhomogeneous magnetic fields induced by direct currents through\nsuperconducting gates. Qubit coupling is based on the exchange interaction, and\nwe show that parallel two-qubit gates can be performed at the detuning noise\ninsensitive point. While the architecture requires a high level of uniformity\nin the materials and critical dimensions to enable shared control, it stands\nout for its simplicity and provides prospects for large-scale quantum\ncomputation in the near future.",
        "positive": "Paraxial propagation of a quantum charge in a random magnetic field: The paraxial (parabolic) theory of a near forward scattering of a quantum\ncharged particle by a static magnetic field is presented. From the paraxial\nsolution to the Aharonov-Bohm scattering problem the transverse transfered\nmomentum (the Lorentz force) is found. Multiple magnetic scattering is\nconsidered for two models: (i) Gaussian $\\delta$ -correlated random magnetic\nfield; (ii) a random array of the Aharonov-Bohm magnetic flux line. The\nparaxial gauge-invariant two-particle Green function averaged with respect to\nthe random field is found by an exact evaluation of the Feynman integral. It is\nshown that in spite of the anomalous character of the forward scattering, the\ntransport properties can be described by the Boltzmann equation. The Landau\nquantization in the field of the Aharonov-Bohm lines is discussed."
    },
    {
        "anchor": "Conductance footprints of impurity scattering in graphene nanoribbons: We report a detailed analytic investigation of the interplay between size\nquantization and local scattering centers in armchair graphene nanoribbons, as\nseen in the conductance. The scattering property of a local scattering center\nis dependent on if it is located on one sublattice (A-site impurity) or both\n(impurity situated at neighboring carbon atoms, A-B-site impurity). The A-site\nimpurity scatters in a similar way as a localized impurity in a one-dimensional\nchannel made from a two-dimensional electron gas. On the other hand, the\nA-B-site impurity introduces A- to B-sublattice scattering, which knows about\nthe chirality of Dirac electrons, and heavily influence the conductance. For\nA-site impurities, interplay between evanescent waves at the impurity and the\npropagating modes contributing to the conductance, leads to scattering\nresonances that generate either dips in the conductance or render the impurity\ncompletely transparent. The latter occurs at subband bottom energies where the\nwave vector of the opening mode is zero. The conductance of defect free\ngraphene therefore remains at these energies. This is analagous to the case of\na scattering center in a quantum channel made from a two-dimensional electron\ngas. The conductance dips occur at energies $\\Delta E$ away from the\nconductance steps and their location depend directly on the impurity strength.\nIn particular, for repulsive impurities the dips occur for hole-doping, while\nfor attractive impurities for electron doping. For an A-B-site impurity, the A-\nto B-sublattice scattering interferes with the transmission resonance at the\nenergies of the subband bottoms and the impurity is never transparent and the\nconductance steps of defect free graphene ribbons are always lost. We derive a\ngeneralized Fisher-Lee formula for graphene leads that holds for arbitrary\nscattering region and arbitrary number of leads.",
        "positive": "Classical to quantum transition of a driven nonlinear nanomechanical\n  resonator: Much experimental effort is invested these days in fabricating\nnanoelectromechanical systems (NEMS) that are sufficiently small, cold, and\nclean, so as to approach quantum mechanical behavior as their typical quantum\nenergy scale $\\hbar\\Omega$ becomes comparable to that of the ambient thermal\nenergy $k_{B}T$. Such systems will hopefully enable one to observe the quantum\nbehavior of human-made objects, and test some of the basic principles of\nquantum mechanics. Here we expand and elaborate on our recent suggestion [PRL\n99 (2007) 040404] to exploit the nonlinear nature of a nanoresonator in order\nto observe its transition into the quantum regime. We study this transition for\nan isolated resonator, as well as one that is coupled to a heat bath at either\nzero or finite temperature. We argue that by exploiting nonlinearities, quantum\ndynamics can be probed using technology that is almost within reach. Numerical\nsolutions of the equations of motion display the first quantum corrections to\nclassical dynamics that appear as the classical-to-quantum transition occurs.\nThis provides practical signatures to look for in future experiments with NEMS\nresonators."
    },
    {
        "anchor": "Genesis of the Floquet Hofstadter butterfly: We investigate theoretically the spectrum of a graphene-like sample\n(honeycomb lattice) subjected to a perpendicular magnetic field and irradiated\nby circularly polarized light. This system is studied using the Floquet\nformalism, and the resulting Hofstadter spectrum is analyzed for different\nregimes of the driving frequency. For lower frequencies, resonances of various\ncopies of the spectrum lead to intricate formations of topological gaps. In the\nLandau-level regime, new wing-like gaps emerge upon reducing the driving\nfrequency, thus revealing the possibility of dynamically tuning the formation\nof the Hofstadter butterfly. In this regime, an effective model may be\nanalytically derived, which allows us to retrace the energy levels that exhibit\navoided crossings and ultimately lead to gap structures with a wing-like shape.\nAt high frequencies, we find that gaps open for various fluxes at $E=0$, and\nupon increasing the amplitude of the driving, gaps also close and reopen at\nother energies. The topological invariants of these gaps are calculated and the\nresulting spectrum is elucidated. We suggest opportunities for experimental\nrealization and discuss similarities with Landau-level structures in non-driven\nsystems.",
        "positive": "Random Interaction Matrix Ensembles in Mesoscopic Physics: We analyze several ground state related properties of mesoscopic systems\nusing the random interaction matrix model EGOE(1+2)-$\\cs$ (or RIMM) for many\nfermion systems with spin degree of freedom and the Hamiltonian containing\npairing and exchange interactions in addition to the mean-field one-body and\nrandom two-body parts. RIMM reproduces the essential features of various\nproperties: odd-even staggering in ground state energies as a function of\nparticle number, delay in ground state magnetization and conductance peak\nspacing distributions. The analytical formula, we have derived, for the\nensemble averaged spectral variances provides a simple understanding of some of\nthese properties."
    },
    {
        "anchor": "Measurement of the Chern Number for Non-Hermitian Chern Insulators: The identification of the topological invariant of a topological system is\ncrucial in experiments. However, due to the inherent non-Hermitian features,\nsuch determination is notably challenging in non-Hermitian systems. Here, we\npropose that the magnetic effect can be utilized to measure the Chern number of\nthe non-Hermitian Chern insulator. We find that the splitting of non-Hermitian\nbands under the magnetic field is Chern number dependent. Consequently, one can\neasily identify the Chern number by analyzing these splitting sub-bands. From\nthe experimental perspective, the measurement of non-Hermitian bands is\ndemonstrated in LC electric circuits. Furthermore, we find that the\nnon-Hermiticity can drive open (closed) orbits of sub-bands in the Hermitian\nlimit closed (open), which can also be identified by our proposal. These\nphenomena highlight the distinctive capabilities of non-Hermitian systems. Our\nresults facilitate the detection of Chern numbers for non-Hermitian systems and\nmay motivate further studies of their topological properties.",
        "positive": "Level spectrum and charge relaxation in a silicon double quantum dot\n  probed by dual-gate reflectometry: We report on dual-gate reflectometry in a metal-oxide-semiconductor\ndouble-gate silicon transistor operating at low temperature as a double quantum\ndot device. The reflectometry setup consists of two radio-frequency resonators\nrespectively connected to the two gate electrodes. By simultaneously measuring\ntheir dispersive response, we obtain the complete charge stability diagram of\nthe device. Charge transitions between the two quantum dots and between each\nquantum dot and either the source or the drain contact are detected through\nphase shifts in the reflected radio-frequency signals. At finite bias,\nreflectometry allows probing charge transitions to excited quantum-dot states\nthereby enabling direct access to the energy level spectra of the quantum dots.\nInterestingly, we find that in the presence of charge transport across the two\ndots the reflectometry signatures of interdot transitions display a dip-peak\nstructure containing quantitative information on the charge relaxation rates in\nthe double quantum dot."
    },
    {
        "anchor": "Extracting the ground-state spin of a quantum dot from the conductance\n  peaks in a parallel magnetic field at finite temperature: We derive a closed expression for the finite-temperature conductance of a\nCoulomb-blockade quantum dot in the presence of an exchange interaction and a\nparallel magnetic field. Parallel-field dependence of Coulomb-blockade peak\nposition has been used to determine experimentally the ground-state spin of\nquantum dots. We find that for a realistic value of the exchange interaction,\nthe peak motion can be significantly affected at temperatures as low as kT ~\n0.1 Delta, with Delta being the mean level spacing in the dot. This temperature\neffect can lead to misidentification of the ground-state spin when a level\ncrossing occurs at low fields. We propose an improved method to determine\nunambiguously the ground-state spin. This method takes into account level\ncrossings and temperature effects at a finite exchange interaction.",
        "positive": "Beyond ideal two-dimensional metals: Edges, vacancies, and\n  polarizabilities: Recent experimental discoveries of graphene-stabilized patches of\ntwo-dimensional (2D) metals have motivated also their computational studies.\nHowever, so far the studies have been restricted to ideal and infinite 2D\nmetallic monolayers, which is insufficient because in reality the properties of\nsuch metallic patches are governed by microstructures pervaded by edges,\ndefects, and several types of perturbations. Here we use density-functional\ntheory to calculate edge and vacancy formation energies of hexagonal and square\nlattices of 45 elemental 2D metals. We find that the edge and vacancy formation\nenergies are strongly correlated and decrease with increasing Wigner-Seitz\nradii, analogously to surface energies. Despite a radical reduction in atomic\ncoordination numbers, the 2D and 3D vacancy formation energies and work\nfunctions are nearly the same for each metal. Finally, static polarizabilities\nreveal a clear cubic dependence on bond length. These trends provide useful\ninsights when moving towards reality with elemental 2D metals."
    },
    {
        "anchor": "Microscopic theory of magnetoconductivity at low magnetic fields in\n  terms of Berry curvature and orbital magnetic moment: Using a microscopic theory for the magnetoconductivity at low magnetic fields\nwe show how the Hall and longitudinal conductivity can be calculated in the low\nscattering rate limit. In the lowest order of the scattering rate, we recover\nthe result of the semiclassical Boltzmann transport theory. At higher order, we\nget corrections containing the Berry curvature and the orbital magnetic moment.\nWe use this formalism to study the linear longitudinal magnetoconductivity in\ntilted Weyl semimetals. We discuss how our result is related to the\nsemiclassical Boltzmann approach and show the differences that arise compared\nto previous studies related to the orbital magnetic moment.",
        "positive": "Magnetoelectric effect in cylindrical topological insulators: Topological insulators (TIs) exhibit a quantized magnetoelectric response\nwhen time-reversal symmetry is broken on its surface. This unusual\nelectromagnetic (EM) response is a unique macroscopic manifestation of the\nquantum Hall effect on the TI surface and it is described by a quantized\nChern-Simons theory. In this paper, we construct the Green's function (GF)\ndescribing the EM response of two topological media separated by a cylindrical\ninterface. This GF, in the appropriate limits, describes the magnetoelectric\neffect of both i) a cylindrical TI surrounded by a dielectric fluid, and ii) a\nTI with a cylindrical dielectric-filled cavity. We calculate the EM fields\nproduced by a line charge and a line current near the TI surface and we show\nthat, in addition to the standard image electromagnetic sources, charge and\ncurrent densities of magnetic monopoles will also appear. We discuss some\nexperimental setups which could be used to test these magnetic monopole fields."
    },
    {
        "anchor": "Formation of Non-reciprocal Bands in Magnetized Diatomic Plasmonic\n  Chains: We show that non-reciprocal bands can be formed in a magnetized periodic\nchain of spherical plasmonic particles with two particles per unit cell.\nSimplified form of symmetry operators in dipole approximations are used to\ndemonstrate explicitly the relation between spectral non-reciprocity and broken\nspatial-temporal symmetries. Due to hybridization among plasmon modes and free\nphoton modes, strong spectral non-reciprocity appears in region slightly below\nthe lightline, where highly directed guiding of energy can be supported. The\nresults may provide a clear guidance on the design of one-way waveguides.",
        "positive": "Magnetotransport in heterostructures of transition metal dichalcogenides\n  and graphene: We use a van-der-Waals pickup technique to fabricate different\nheterostructures containing WSe$_2$(WS$_2$) and graphene. The heterostructures\nwere structured by plasma etching, contacted by one-dimensional edge contacts\nand a topgate was deposited. For graphene/WSe$_2$/SiO$_2$ samples we observe\nmobilities of $\\sim$12 000 cm$^2$/Vs. Magnetic field dependent resistance\nmeasurements on these samples show a peak in the conductivity at low magnetic\nfield. This dip is attributed to the weak antilocalization (WAL) effect,\nstemming from spin-orbit coupling. Samples where graphene is encapsulated\nbetween WSe$_2$(WS$_2$) and hBN show a much higher mobility of up to $\\sim$120\n000 cm$^2$/Vs. However, in these samples no WAL peak can be observed. We\nattribute this to a transition from the diffusive to the quasiballistic regime.\nAt low magnetic field a resistance peak appears, which we ascribe to a size\neffect, due to boundary scattering. Shubnikov-de Haas oscillations in fully\nencapsulated samples show all integer filling factors, due to complete lifting\nof the spin and valley degeneracy."
    },
    {
        "anchor": "Length-independent quantum transport through topological band states of\n  graphene nanoribbons: Atomically precise graphene nanoribbons (GNRs) have emerged as promising\ncandidates for nanoelectronic applications due to their widely tunable energy\nband gaps resulting from lateral quantum confinement and edge effects. Here we\nreport on the electronic transport characterization of an edge-modified GNR\nsuspended between the tip of a scanning tunneling microscope (STM) and a\nAu(111) substrate. Differential conductance measurements on this\nmetal-GNR-metal junction reveal loss-less transport properties (inverse decay\nlength $\\beta < 0.001 /\\overset{\\circ}{\\mathrm{A}}$) with high conductance\n($\\sim 0.1$ G$_0$) at low voltages (50 meV) over long distances ($z > 10$ nm).\nThe transport behavior is sensitive to the coupling between ribbon and\nelectrodes, an effect that is rationalized using tight-binding and density\nfunctional theory simulations. From extensive modelling we infer that the\nlength-independent transport is a manifestation of band transport through\ntopological valence states, which originate from the zigzag segments on the GNR\nedges.",
        "positive": "Electron-phonon bound states and impurity band formation in quantum\n  wells: A generalized propagation matrix method is used to study how scattering off\nlocal Einstein phonons affects resonant electron transmission through quantum\nwells. In particular, the parity and the number of the phonon mediated\nsatellite resonances are found to depend on the available scattering channels.\nFor a large number of phonon channels, the formation of low-energy impurity\nbands is observed. Furthermore, an effective theory is developed which\naccurately describes the phonon generated sidebands for sufficiently small\nelectron-phonon coupling. Finally, the current-voltage characteristics caused\nby phonon assisted transmission satellites are discussed for a specific double\nbarrier geometry."
    },
    {
        "anchor": "Aharonov-Bohm oscillations and electron gas transitions in hexagonal\n  core-shell nanowires with an axial magnetic field: We use spin-density-functional theory within an envelope function approach to\ncalculate electronic states in a GaAs/InAs core-shell nanowire pierced by an\naxial magnetic field. Our fully 3D quantum modeling includes explicitly the\ndescription of the realistic cross-section and composition of the sample, and\nthe electrostatic field induced by external gates in two different device\ngeometries, gate-all-around and back-gate. At low magnetic fields, we\ninvestigate Aharonov-Bohm oscillations and signatures therein of the discrete\nsymmetry of the electronic system, and we critically analyze recent\nmagnetoconductance observations. At high magnetic fields we find that several\ncharge and spin transitions occur. We discuss the origin of these transitions\nin terms of different localization and Coulomb regimes and predict their\nsignatures in magnetoconductance experiments.",
        "positive": "Effect of Andreev Processes on the Goos-H\u00e4nchen (GH) shift in the\n  Graphene-Superconductor-Graphene (GSG) junctions: In this article, we study the transport properties of\nGraphene-Superconductor-Graphene (GSG) heterojunction where the superconducting\nregion is created in the middle of a graphene sheet, as contrasted to widely\nstudied transport properties through a Superconductor-Graphene-Superconductor\n(SGS) type of Josephson junction. We particularly analyse in detail the\nGoos-H\\\"anchen shift of the electron and the hole at the GS interface in such a\njunction, due to normal as well as Andreev reflection, using a transfer\nmatrix-based approach. Additionally, we evaluate the normalised differential\nconductance as a function of bias voltage that characterises the transport\nthrough such junction and point out how they are influenced by Andreev and\nnormal reflection. In the subsequent parts of the article we demonstrate how\nthe GH shift for both electron and hole changes with the width of the\nsuperconducting region. The behavior of the differential conductance in such\njunctions as a function of the bias voltage in the region, dominated by Andreev\nand normal reflection, is also presented and analysed."
    },
    {
        "anchor": "Conductance correlations in a mesoscopic spin glass wire : a numerical\n  Landauer study: In this letter we study the coherent electronic transport through a metallic\nnanowire with magnetic impurities. The spins of these impurities are considered\nas frozen to mimic a low temperature spin glass phase. The transport properties\nof the wire are derived from a numerical Landauer technique which provides the\nconductance of the wire as a function of the disorder configuration. We show\nthat the correlation of conductance between two spin configurations provides a\nmeasure of the correlation between these spin configurations. This correlation\ncorresponds to the mean field overlap in the absence of any spatial order\nbetween the spin configurations. Moreover, we find that these conductance\ncorrelations are sensitive to the spatial order between the two spin\nconfigurations, i.e whether the spin ?ips between them occur in a compact\nregion or not.",
        "positive": "Density matrix purification due to continuous quantum measurement: We consider the continuous quantum measurement of a two-level system, for\nexample, a single-Cooper-pair box measured by a single-electron transistor or a\ndouble-quantum dot measured by a quantum point contact. While the approach most\ncommonly used describes the gradual decoherence of the system due to the\nmeasurement, we show that when taking into account the detector output, we get\nthe opposite effect: gradual purification of the density matrix. The\ncompetition between purification due to measurement and decoherence due to\ninteraction with the environment can be described by a simple Langevin equation\nwhich couples the random evolution of the system density matrix and the\nstochastic detector output. The gradual density matrix purification due to\ncontinuous measurement may be verified experimentally using present-day\ntechnology. The effect can be useful for quantum computing."
    },
    {
        "anchor": "Short-Lived Electron Transfer in Donor-Bridge-Acceptor Systems: We investigate time-dependent electron transfer (ET) in benchmark\ndonor-bridge-acceptor systems. For the small bridge sizes studied, we obtain\nresults far different from the perturbation theory which underlies\nscattering-based approaches, notably a lack of destructive interference in the\nET for certain arrangements of bridge molecules. We also calculate wavepacket\ntransmission in the non-steady-state regime, finding a featureless spectrum,\nwhile for the current we find two types of transmission: sequential and direct,\nwhere in the latter, the current transmission increases as a function of the\nenergy of the transferred electron, a regime inaccessible by conventional\nscattering theory.",
        "positive": "Nonlinear acousto-electric transport in a two-dimensional electron\n  system: We study both theoretically and experimentally the nonlinear interaction\nbetween an intense surface acoustic wave and a two-dimensional electron plasma\nin semiconductor-piezocrystal hybrid structures. The experiments on hybrid\nsystems exhibit strongly nonlinear acousto-electric effects. The plasma turns\ninto moving electron stripes, the acousto-electric current reaches its maximum,\nand the sound absorption strongly decreases. To describe the nonlinear\nphenomena, we develop a coupled-amplitude method for a two-dimensional system\nin the strongly nonlinear regime of interaction. At low electron densities the\nabsorption coefficient decreases with increasing sound intensity, whereas at\nhigh electron density the absorption coefficient is not a monotonous function\nof the sound intensity. High-harmonic generation coefficients as a function of\nthe sound intensity have a nontrivial behavior. Theory and experiment are found\nto be in a good agreement."
    },
    {
        "anchor": "Design of electron wave filters in monolayer graphene by tunable\n  transmission gap: We have investigated the transmission in monolayer graphene barrier at\nnonzero angle of incidence. Taking the influence of parallel wave vector into\naccount, the transmission as the function of incidence energy has a gap due to\nthe evanescent waves in two cases of Klein tunneling and classical motion. The\nmodulation of the transmission gap by the incidence angle, the height, and\nwidth of potential barrier may lead to potential applications in graphene-based\nelectronic devices.",
        "positive": "Enhancement of electron magnetic susceptibility due to many-body\n  interactions in monolayer MoSe$_2$: Employing the original, all-optical method, we quantify the magnetic\nsusceptibility of a two-dimensional electron gas (2DEG) confined in the\nMoSe$_2$ monolayer in the range of low and moderate carrier densities. The\nimpact of electron-electron interactions on the 2DEG magnetic susceptibility is\nfound to be particularly strong in the limit of, studied in detail, low carrier\ndensities. Following the existing models, we derive the value of $g_0 = 2.5 \\pm\n0.4$ for the bare (in the absence of the interaction effects) $g$-factor of the\nground state electronic band in the MoSe$_2$ monolayer. The derived value of\nthis parameter is discussed in the context of estimations from other\nexperimental approaches. Surprisingly, the conclusions drawn differ from\ntheoretical ab-initio studies."
    },
    {
        "anchor": "Comparative analysis of resonant phonon THz quantum cascade lasers: We present a comparative analysis of a set of GaAs-based THz quantum cascade\nlasers, based on longitudinal-optical phonon scattering depopulation, by using\nan ensemble Monte Carlo simulation, including both carrier-carrier and\ncarrier-phonon scattering. The simulation shows that the parasitic injection\ninto the states below the upper laser level limits the injection efficiency and\nthus the device performance at the lasing threshold. Additional detrimental\neffects playing an important role are identified. The simulation results are in\nreasonable agreement with the experimental findings.",
        "positive": "Multiscale simulations of uni-polar hole transport in (In,Ga)N quantum\n  well systems: Understanding the impact of the alloy micro-structure on carrier transport\nbecomes important when designing III-nitride-based LED structures. In this\nwork, we study the impact of alloy fluctuations on the hole carrier transport\nin (In,Ga)N single and multi-quantum well systems. To disentangle hole\ntransport from electron transport and carrier recombination processes, we focus\nour attention on uni-polar (p-i-p) systems. The calculations employ our\nrecently established multi-scale simulation framework that connects atomistic\ntight-binding theory with a macroscale drift-diffusion model. In addition to\nalloy fluctuations, we pay special attention to the impact of quantum\ncorrections on hole transport. Our calculations indicate that results from a\nvirtual crystal approximation present an upper limit for the hole transport in\na p-i-p structure in terms of the current-voltage characteristics. Thus we find\nthat alloy fluctuations can have a detrimental effect on hole transport in\n(In,Ga)N quantum well systems, in contrast to uni-polar electron transport.\nHowever, our studies also reveal that the magnitude by which the random alloy\nresults deviate from virtual crystal approximation data depends on several\nfactors, e.g. how quantum corrections are treated in the transport\ncalculations."
    },
    {
        "anchor": "Transport modulation of graphene nanoribbons with side-attached organic\n  molecules: In this work we address the effects on the conductance of graphene\nnanoribbons (GNRs) at which organic molecules are side-attached on the ribbon\nends. For simplicity, only armchair (AGNRs) and zigzag (ZGNRs) nanoribbons are\nconsidered and quasi one-dimensional molecules, such as linear poly-aromatic\nhydrocarbon (LPHC) and poly(para-phenylene), are chosen. The conductance of the\nGNRs exhibit a particular behavior as a function of the length of the organic\nmolecules: the energy spectrum of the quasi one-dimensional system is clearly\nreflected in the conductance curves of the GNRs. The results suggest that GNRs\ncan be used as an spectrograph-sensor device. An even-odd parity effect, as a\nfunction of the length of the attached molecules, can be observed in the\nconductance of these system. The nanostructures are described using a\nsingle-band tight binding Hamiltonian and the electronic conductance and the\ndensity of states of the systems are calculated within the Green's function\nformalism based on real-space renormalization techniques.",
        "positive": "Quantum transport through MoS$_2$ constrictions defined by photodoping: We present a device scheme to explore mesoscopic transport through molybdenum\ndisulfide (MoS$_2$) constrictions using photodoping. The devices are based on\nvan-der-Waals heterostructures where few-layer MoS$_2$ flakes are partially\nencapsulated by hexagonal boron nitride (hBN) and covered by a few-layer\ngraphene flake to fabricate electrical contacts. Since the as-fabricated\ndevices are insulating at low temperatures, we use photo-induced remote doping\nin the hBN substrate to create free charge carriers in the MoS$_2$ layer. On\ntop of the device, we place additional metal structures, which define the shape\nof the constriction and act as shadow masks during photodoping of the\nunderlying MoS$_2$/hBN heterostructure. Low temperature two- and four-terminal\ntransport measurements show evidence of quantum confinement effects."
    },
    {
        "anchor": "Deep Learning for Spin-Orbit Torque Characterizations with a Projected\n  Vector Field Magnet: Spin-orbit torque characterizations on magnetic heterostructures with\nperpendicular anisotropy are demonstrated on a projected vector field magnet\nvia hysteresis loop shift measurement and harmonic Hall measurement with planar\nHall correction. Accurate magnetic field calibration of the vector magnet is\nrealized with the help of deep learning models, which are able to capture the\nnonlinear behavior between the generated magnetic field and the currents\napplied to the magnet. The trained models can successfully predict the applied\ncurrent combinations under the circumstances of magnetic field scans, angle\nscans, and hysteresis loop shift measurements. The validity of the models is\nfurther verified, complemented by the comparison of the spin-orbit torque\ncharacterization results obtained from the deep-learning-trained vector magnet\nsystem with those obtained from a conventional setup comprised of two separated\nelectromagnets. The damping-like spin-orbit torque (DL-SOT) efficiencies\n(|$\\xi_{DL}$|) extracted from the vector magnet and the traditional measurement\nconfiguration are consistent, where |$\\xi_{DL}$| $\\approx$ 0.22 for amorphous W\nand |$\\xi_{DL}$| $\\approx$ 0.02 for $\\alpha$-W. Our work provides an advanced\nmethod to meticulously control a vector magnet and to conveniently perform\nvarious spin-orbit torque characterizations.",
        "positive": "Polarization dependence of coherent phonon generation and detection in\n  the 3D topological insulator Bi2Te3: We have studied the polarization dependence of coherent phonons in the\ntopological insulator Bi2Te3. Using polarization-dependent femtosecond\npump-probe spectroscopy, we measured coherent phonons as a function of angle\nwhen the pump and probe polarizations were fixed, and the crystal orientation\nwas rotated. For isotropic detection, depending on the spot position,\noscillations either from only low- and high-frequency phonons of A1g symmetry,\nor in addition from the mode at 3.6 THz were observed. All the modes were found\nto be independent of the orientation of electric field vector with respect to\nthe crystal axes testifying to their full symmetry while no modes of lower\nsymmetry appeared in any polarization geometry. For anisotropic detection both\nmodes of Eg symmetry could be detected, but their amplitudes were considerably\nsmaller than those of A1g symmetry. To clarify the coherent phonon assignment\nand the process of coherent phonon generation in Bi2Te3, the time-domain\nmeasurements were complemented by spontaneous Raman scattering. The comparison\nof frequency- and time-domain results and the polarization dependence suggest\nthat the 3.6 THz mode belongs to crystalline Te arising due to tellurium\nsegregation. A discrepancy between the time- and frequency domain data is\ndiscussed."
    },
    {
        "anchor": "Electron-electron interaction in graphene at finite Fermi energy: The wave equation describing the interaction of two electrons in graphene at\narbitrary value of the Fermi energy $E_F$ is derived. For the solutions of this\nequation, we have found the explicit forms of the density and the current which\nobey the continuity equation. We have traced the evolution of the wave packet\nduring a scattering process. It is shown that the long-leaving localized\nquasi-stationary peak may appear at $E_F<0$ . Then this peak decays into a set\nof wave packets following each other. At $t\\rightarrow\\infty$ a total norm of\nall outgoing wave packets equals to that of incoming wave packet. At $E_F=0$\nthe localized state does not appear. For $E_F<0$ there is an infinite set of\nthe localized solutions with the finite norms.",
        "positive": "Effect of charged line defects on conductivity in graphene: numerical\n  Kubo and analytical Boltzmann approaches: Charge carrier transport in single-layer graphene with one-dimensional\ncharged defects is studied theoretically. Extended charged defects, considered\nan important factor for mobility degradation in chemically-vapor-deposited\ngraphene, are described by a self-consistent Thomas-Fermi potential. A\nnumerical study of electronic transport is performed by means of a\ntime-dependent real-space Kubo approach in honeycomb lattices containing\nmillions of carbon atoms, capturing the linear response of realistic size\nsystems in the highly disordered regime. Our numerical calculations are\ncomplemented with a kinetic transport theory describing charge transport in the\nweak scattering limit. The semiclassical transport lifetimes are obtained by\ncomputing scattered amplitudes within the second Born approximation. The\ntransport electron-hole asymmetry found in the semiclassical approach is\nconsistent with the Kubo calculations. In the strong scattering regime, the\nconductivity is found to be a sublinear function of electronic density and\nweakly dependent on the Thomas-Fermi screening wavelength. We attribute this\natypical behavior to the extended nature of one-dimensional charged defects.\nOur results are consistent with recent experimental reports."
    },
    {
        "anchor": "Surface plasmons at the interface between graphene and kerr-type\n  nonlinear medium: The properties of surface plasmons localized at the interface between\ngraphene and kerr-type nonlinear medium in three dimensions are investigated.\nCompared with surface plasmons at the surface of metal, with the inevitable\nnonlinear refractive effect, the confinement of plasmon can be improved to\nthree times than graphene plasmons without nonlinear contribution, but also\nwith almost the same relative propagation length. Moreover, the dispersion\nrelation and propation distance of graphene plasmons can be easily controlled\nby changing the fermi energy, temperature and relaxation time of graphene. Our\nresults suggest a simple but useful potential application for precise nonlinear\nmaterial sensor using graphene plasmons.",
        "positive": "Fabrication of quantum point contacts by engraving\n  GaAs/AlGaAs-heterostructures with a diamond tip: We use the all-diamond tip of an atomic force microscope for the direct\nengraving of high quality quantum point contacts in\nGaAs/AlGaAs-heterostructures. The processing time is shortened by two orders of\nmagnitude compared to standard silicon tips. Together with a reduction of the\nline width to below 90 nm the depletion length of insulating lines is reduced\nby a factor of two with the diamond probes. The such fabricated defect free\nballistic constrictions show well resolved conductance plateaus and the 0.7\nanomaly in electronic transport measurements."
    },
    {
        "anchor": "Effect of the external fields in high Chern number quantum anomalous\n  Hall insulators: A quantum anomalous Hall state with high Chern number has so far been\nrealized in multiplayer structures consisting of alternating magnetic and\nundoped topological insulator layers. However, in previous proposals, the Chern\nnumber can be only tuned by varying the doping concentration or the width of\nthe magnetic topological insulator layers. This drawback largely restrict the\napplications of dissipationless chiral edge currents in electronics since the\nnumber of conducting channels remains fixed. In this work, we propose a way of\nvarying the Chern number at will in these multilayered structures by means of\nan external electric field applied along the stacking direction. In the\npresence of an electric field in the stacking direction, the inverted bands of\nthe unbiased structure coalesce and hybridize, generating new inverted bands\nand collapsing the previously inverted ones. In this way, the number of Chern\nstates can be tuned externally in the sample, without the need of modifying the\nnumber and width of the layers or the doping level. We showed that this effect\ncan be uncovered by the variation of the transverse conductance as a function\nof the electric field at constant injection energy at the Fermi level.",
        "positive": "Interaction-driven topological insulator states in strained graphene: The electronic properties of graphene can be manipulated via mechanical\ndeformations, which opens prospects for studying the Dirac fermions in new\nregimes and for new device applications. Certain natural configurations of\nstrain generate large nearly uniform pseudo-magnetic fields, which have\nopposite signs in the two valleys, and give rise to flat spin- and\nvalley-degenerate pseudo Landau levels (PLLs). Here we consider the effect of\nthe Coulomb interactions in strained graphene with uniform pseudo-magnetic\nfield. We show that the spin/valley degeneracies of the PLLs get lifted by the\ninteractions, giving rise to topological insulator-like states. In particular,\nwhen a nonzero PLL is quarter- or three-quarter filled, an anomalous quantum\nHall state spontaneously breaking time-reversal symmetry emerges. At\nhalf-filled PLL, weak spin-orbital interaction stabilizes\ntime-reversal-symmetric quantum spin-Hall state. These many-body states are\ncharacterized by the quantized conductance and persist to a high temperature\nscale set by the Coulomb interactions, which we estimate to be a few hundreds\nKelvin at moderate strain values. At fractional fillings, fractional quantum\nHall states breaking valley symmetry emerge. These results suggest a new route\nto realizing robust topological insulator states in mesoscopic graphene."
    },
    {
        "anchor": "Emission and amplification of surface plasmons in resonant - tunneling\n  van der Waals heterostructures: We predict a new mechanism of surface plasmon amplification in\ngraphene-insulator-graphene van der Waals heterostructures. The amplification\noccurs upon the stimulated interlayer electron tunneling accompanied by the\nemission of a coherent plasmon. The quantum-mechanical calculations of the\nnon-local high-frequency tunnel conductivity show that a relative smallness of\nthe tunneling exponent can be compensated by a strong resonance due to the\nenhanced tunneling between electron states with collinear momenta in the\nneighboring graphene layers. With the optimal selection of the barrier layer,\nthe surface plasmon gain due to the inelastic tunneling can compensate or even\nexceed the loss due to both Drude and interband absorption. The tunneling\nemission of the surface plasmons is robust against a slight twist of the\ngraphene layers and might explain the electroluminescence from the\ntunnel-coupled graphene layers observed in the recent experiments.",
        "positive": "Highly anisotropic optical conductivities in two-dimensional tilted\n  semi-Dirac bands: Within linear response theory, the absorptive part of highly anisotropic\noptical conductivities are analytically calculated for distinct tilts in\ntwo-dimensional (2D) tilted semi-Dirac bands (SDBs). The transverse optical\nconductivities always vanish. The interband longitudinal optical conductivities\n(LOCs) in 2D tilted SDBs differ qualitatively in the power-law scaling of\n$\\omega$ as\n$\\mathrm{Re}\\sigma_{\\perp}^{\\mathrm{IB}}(\\omega)\\propto\\sigma_0\\sqrt{\\omega}$\nand\n$\\mathrm{Re}\\sigma_{\\parallel}^{\\mathrm{IB}}(\\omega)\\propto\\sigma_0/\\sqrt{\\omega}$.\nBy contrast, the intraband LOCs in 2D tilted SDBs depend on $\\mu$ in the\npower-law scaling as\n$\\mathrm{Re}\\sigma_{\\perp}^{\\mathrm{D}}(\\omega)\\propto\\sigma_0\\mu \\sqrt{\\mu}$\nand\n$\\mathrm{Re}\\sigma_{\\parallel}^{\\mathrm{D}}(\\omega)\\propto\\sigma_0\\mu/\\sqrt{\\mu}$.\nThe tilt-dependent behaviors of LOCs could qualitatively characterize distinct\nimpact of band tilting in 2D tilted SDBs. In particular, for arbitrary tilt $t$\nsatisfying $0<t\\le 2$, the interband LOCs always possess a robust fixed point\nat $\\omega=2\\mu$. The power-law scalings and tilt-dependent behaviors further\ndictate significant differences in the asymptotic background values and angular\ndependence of LOCs. Our theoretical predictions should be valid for a broad\nclass of 2D tilted SDB materials, and can also be used to fingerprint 2D tilted\nSDB from 2D untilted SDB as well as tilted Dirac bands."
    },
    {
        "anchor": "Intrinsic spin current for an arbitrary Hamiltonian and scattering\n  potential: We have described electron spin dynamics in the presence of the spin-orbit\ninteraction and disorder using the spin-density matrix method. Exact solution\nis obtained for an arbitrary 2D spin-orbit Hamiltonian and arbitrary smoothness\nof the disorder potential. Spin current depends explicitely on the disorder\nproperties, namely the smoothness of the disorder potential, even in the\nballistic limit when broadening by scattering is much smaller than the\nspin-orbit related splitting of the energy spectrum. In this sense universal\nintrinsic spin current does not exist.",
        "positive": "Effects of optical fields on the tunneling time of chiral electrons in\n  graphene: The influences of optical fields on the tunneling time in graphene are\ninvestigated in real time using the finite-difference time-domain method. The\ntunneling time of electrons irradiated by an optical field is significantly\ndifferent from that observed in traditional quantum tunneling. We found that\nwhen the barrier width increases, the group delay becomes constant for the\nreflected wave packet, but increases linearly for the transmitted wave packet.\nThis peculiar tunneling effect can be attributed to current leakage in a\ntime-dependent barrier generated via the optical Stark effect."
    },
    {
        "anchor": "Coulomb blockade and quantum confinement in field electron emission from\n  heterostructured nanotips: A new field electron emission (FE) mechanism, which includes Coulomb blockade\nand quantum confinement effects, is revealed for heterostructured emitters\ncomposed of quantum dots and nanowires self-assembled at diamond nanotips. The\ntotal energy distributions of the emitted electrons show multiple peaks\nattributed to the discrete electronic states of the quantum-confined emitter\nwith the corresponding energy levels oscillating as a function of the applied\nvoltage due to the Coulomb blockade. The FE current-voltage characteristics\nexhibit a modified Coulomb staircase with additional steps becoming more\npronounced with increasing voltage. The experimentally observed behavior is\nconsistent with numerical simulations based on the model of Coulomb blockade in\nquantum dots in combination with the theory of FE from sharp tips.",
        "positive": "Geometric phase-control of a spin-torque oscillator: We show that the phase of a spin-torque oscillator generically acquires a\ngeometric contribution upon slow and cyclic variation of the parameters that\ngovern its dynamics. As an example, we compute the geometric phase that results\nfrom a cyclic excursion of the magnitude of the external field and the current.\nWe consider thermal phase fluctuations and conclude that the geometric phase\nshould be experimentally observable at room temperature with current setups. We\nbriefly comment on arrays of spin-torque oscillators and possible applications."
    },
    {
        "anchor": "Topological superconductivity at finite temperatures in proximitized\n  magnetic nanowires: Performing Monte Carlo simulations we study the temperature dependent\nself--organization of magnetic moments coupled to itinerant electrons in a\nfinite--size one--dimensional nanostructure proximitized to a superconducting\nreservoir. At low temperature an effective interaction between the localized\nmagnetic moments, that is mediated by itinerant electrons, leads to their\nhelical ordering. This ordering, in turn, affects the itinerant electrons,\ninducing the topologically nontrivial superconducting phase that hosts the\nMajorana modes. In a~wide range of system parameters, the spatial periodicity\nof a spiral order that minimizes the ground state energy turns out to promote\nthe topological phase. We determine the correlation length of such spiral order\nand study how it is reduced by thermal fluctuations. This reduction is\naccompanied by suppression of the topological gap (which separates the\nzero-energy mode from continuum), setting the upper (critical) temperature for\nexistence of the Majorana quasiparticles. Monte Carlo simulations do not rely\non any ansatz for configurations of the localized moments, therefore they can\nbe performed for arbitrary model parameters, also beyond the perturbative\nregime.",
        "positive": "Zero field line in the magnetic spectra of negatively charged\n  nitrogen-vacancy centers in diamond: The dependence of the luminescence of diamonds with negatively charged\nnitrogen-vacancy centers (NV-) vs. applied magnetic field (magnetic spectrum)\nwas studied. A narrow line in zero magnetic field was discovered. The\nproperties of this line are considerably different from those of other narrow\nmagnetic spectrum lines. Its magnitude is weakly dependent of the orientation\nof the single-crystal sample to the external magnetic field. This line is also\nobserved in a powdered sample. The shape of the line changes greatly when\nexcitation light polarization is varied. The magnitude of the line has a\nnon-linear relation to excitation light intensity. For low intensities this\ndependence is close to a square law. To explain the mechanism giving rise to\nthis line in the magnetic spectrum, we suggest a model based on the\ndipole-dipole interaction between different NV- centers."
    },
    {
        "anchor": "Level attraction and exceptional points in a resonant spin-orbit torque\n  system: Level attraction can appear in driven systems where instead of repulsion two\nmodes coalesce in a region separated by two exceptional points. This behavior\nwas proposed for optomechanical and optomagnonic systems, and recently observed\nfor dissipative cavity magnon-polaritons. We demonstrate that such a regime\nexists in a spin-orbit torque system where a magnetic oscillator is resonantly\ncoupled to an electron reservoir. An instability mechanism necessary for mode\nattraction can be provided by applying an electric field. The field excites\ninterband transitions between spin-orbit split bands leading to an instability\nof the magnetic oscillator. Two exceptional points then appear in the\noscillator energy spectrum and the region of instability. We discuss conditions\nunder which this can occur and estimate the electric field strength necessary\nfor reaching the attraction region for a spin-orbit torque oscillator with\nRashba coupling. A proposal for experimental detection is made using magnetic\nsusceptibility measurements.",
        "positive": "Magic numbers for vibrational frequency of charged particles on a sphere: Finding minimum energy distribution of $N$ charges on a sphere is known as\nthe Thomson problem. Here, we study the vibrational properties of the $N$\ncharges in the lowest energy state within the harmonic approximation for $10\\le\nN\\le 200$ and for selected sizes up to $N=372$. The maximum frequency\n$\\omega_{\\rm max}$ increases with $N^{3/4}$, which is rationalized by studying\nthe lattice dynamics of a two-dimensional triangular lattice. The\n$N$-dependence of $\\omega_{\\rm max}$ identifies magic numbers of $N=12, 32, 72,\n132, 192, 212, 272, 282$, and 372, reflecting both a strong degeneracy of\none-particle energies and an icosahedral structure that the $N$ charges form.\n$N=122$ is not identified as a magic number for $\\omega_{\\rm max}$ because the\nformer condition is not satisfied. The magic number concept can hold even when\nan average of high frequencies is considered. The maximum frequency mode at the\nmagic numbers has no anomalously large oscillation amplitude (i.e., not a\ndefect mode)."
    },
    {
        "anchor": "Engineering single donor detectors in doped silicon: We demonstrate the possibility of engineering a single donor transistor\ndirectly from a phosphorous doped quantum dot by making use of the intrinsic\nglassy behaviour of the structure as well as the complex electron dynamics\nduring cooldown. Characterisation of the device at low temperatures and in\nmagnetic field shows single donors can be electrostatically isolated near one\nof the tunnel barrier with either a single or a doubly occupancy. Such a model\nis well supported by capacitance-based simulations. Ability of using the D0 of\nsuch isolated donor as a charge detector is demonstrated by observing the\ncharge stability diagram of a nearby and capacitively coupled semi-connected\ndouble quantum dot.",
        "positive": "Large-deviation analysis for counting statistics in mesoscopic\n  transports: We present an efficient approach, based on a number-conditioned master\nequation, for large-deviation analysis in mesoscopic transports. Beyond the\nconventional full-counting-statistics study, the large-deviation approach\nencodes complete information of both the typical trajectories and the rare\nones, in terms of revealing a continuous change of the dynamical phase in\ntrajectory space. The approach is illustrated with two examples: (i) transport\nthrough a single quantum dot, where we reveal the inhomogeneous distribution of\ntrajectories in general case and find a particular scale invariance point in\ntrajectory statistics; and (ii) transport through a double dots, where we find\na dynamical phase transition between two distinct phases induced by the Coulomb\ncorrelation and quantum interference."
    },
    {
        "anchor": "Domain-wall complexes in ferromagnetic stripes: Interaction of domain walls (DWs) in ferromagnetic stripes is studied with\nrelevance to the formation of stable complexes of many domains. Two DW system\nis described with the Landau-Lifshitz-Gilbert equation including regimes of\nnarrow and wide stripes which correspond the presence of transverse and vortex\nDWs. The DWs of both kinds are characterized with their chiralities (the\ndirection of the magnetization rotation in the stripe plane) and polarities\n(the magnetization orientation in the center of a vortex and/or halfvortices),\nhence, their interactions are analyzed with dependence on these properties. In\nparticular, pairs of the DWs of opposite or like both chiralities and\npolarities are investigated as well as pairs of opposite (like) chiralities and\nof like (opposite) polarities. Conditions of the creation of stationary\nmagnetic bubbles built of two interacting DWs are formulated with relevance to\nthe situations of presence and absence of the external magnetic field.",
        "positive": "Bell-state preparation for electron spins in a semiconductor double\n  quantum dot: A robust scheme for state preparation and state trapping for the spins of two\nelectrons in a semiconductor double quantum dot is presented. The system is\nmodeled by two spins coupled to two independent bosonic reservoirs. Decoherence\neffects due to this environment are minimized by application of optimized\ncontrol fields which make the target state to the ground state of the isolated\ndriven spin system. We show that stable spin entanglement with respect to pure\ndephasing is possible. Specifically, we demonstrate state trapping in a\nmaximally entangled state (Bell state) in the presence of decoherence."
    },
    {
        "anchor": "Impurity-induced resonant states in topological nodal-line semimetals: Nodal-line semimetals are characterized by a kind of topologically nontrivial\nbulk-band crossing, giving rise to almost flat surface states. Yet, a direct\nevidence of the surface states is still lacking. Here we study theoretically\nimpurity effects in topological nodal-line semimetals based on the T-matrix\nmethod. It is found that for a bulk impurity, some in-gap states may be induced\nnear the impurity site, while the visible resonant impurity state can only\nexist for certain strength of the impurity potentials. For a surface impurity,\nrobust resonant impurity states exist in a wide range of impurity potentials.\nSuch robust resonant states stem from the topological protected weak dispersive\nsurface states, which can be probed by scanning tunneling microscopy, providing\na strong signature of the topological surface states in the nodal-line\nsemimetals.",
        "positive": "Electric-field modulation of linear dichroism and Faraday rotation in\n  few-layer phosphorene: Electro-optical modulators, which use an electric voltage (or an electric\nfield) to modulate a beam of light, are essential elements in present-day\ntelecommunication devices. Using a self-consistent tight-binding approach\ncombined with the standard Kubo formula, we show that the optical conductivity\nand the linear dichroism of few-layer phosphorene can be modulated by a\nperpendicular electric field. We find that the field-induced charge screening\nplays a significant role in modulating the optical conductivity and the linear\ndichroism. Distinct absorption peaks are induced in the conductivity spectrum\ndue to the strong quantum confinement along the out-of-plane direction and to\nthe field-induced forbidden-to-allowed transitions. The field modulation of the\nlinear dichroism becomes more pronounced with increasing number of phosphorene\nlayers. We also show that the Faraday rotation is present in few-layer\nphosphorene even in the absence of an external magnetic field. This optical\nHall effect is induced by the reduced lattice symmetry of few-layer\nphosphorene. The Faraday rotation is greatly influenced by the field-induced\ncharge screening and is strongly dependent on the strength of perpendicular\nelectric field and on the number of phosphorene layers."
    },
    {
        "anchor": "Parallel pumping of electrons: We present simultaneous operation of ten single-electron turnstiles leading\nto one order of magnitude increase in current level up to 100 pA. Our analysis\nof device uniformity and background charge stability implies that the\nparallelization can be made without compromising the strict requirements of\naccuracy and current level set by quantum metrology. In addition, we discuss\nhow offset charge instability limits the integration scale of single-electron\nturnstiles.",
        "positive": "Interlayer RKKY Coupling in Bulk Rashba Semiconductors under Topological\n  Phase Transition: The bulk Rashba semiconductors BiTeX (X=I, Cl and Br) with intrinsically\nenhanced Rashba spin-orbit coupling provide a new platform for investigation of\nspintronic and magnetic phenomena in materials. We theoretically investigate\nthe interlayer exchange interaction between two ferromagnets deposited on\nopposite surfaces of a bulk Rashba semiconductor BiTeI in its trivial and\ntopological insulator phases. In the trivial phase BiTeI, we find that for\nferromagnets with a magnetization orthogonal to the interface, the exchange\ncoupling is reminiscent of that of a conventional three-dimensional metal.\nRemarkably, ferromagnets with a magnetization parallel to the interface display\na magnetic exchange qualitatively different from that of conventional\nthree-dimensional metal due to the spin-orbit coupling. In this case, the\ninterlayer exchange interaction acquires two periods of oscillations and decays\nas the inverse of the thickness of the BiTeI layer. For topological BiTeI, the\nmagnetic exchange interaction becomes mediated only by the helical surface\nstates and acts between the one-dimensional spin chains at the edges of the\nsample. The surface state-mediated interlayer exchange interaction allows for\nthe coupling of ferromagnets with non-collinear magnetization and displays a\ndecay power different from that of trivial BiTeI, allowing the detection of the\ntopological phase transition in this material. Our work provides insights into\nthe magnetic properties of these newly discovered materials and their possible\nfunctionalization."
    },
    {
        "anchor": "Inelastic transport dynamics through attractive impurity in charge Kondo\n  regime: Within the frame of quantum dissipation theory, we develop a new hierarchical\nequations of motion theory, combined with the small polaron transformation. We\nfully investigate the electron transport of a single attractive impurity system\nwith the strong electron-phonon coupling in charge- Kondo regime. Numerical\nresults demonstrate the following facts: (i) The density of states curve shows\nthat the attraction mechanism results in not only the charge-Kondo resonance\n(i.e. elastic pair-transition resonance), but also the inelastic\npair-transition resonances and inelastic cotunneling resonances. These signals\nare separated discernibly in asymmetric levels about Fermi level; (ii) The\ndifferential conductance spectrum shows the distinct peaks or wiggles and the\nabnormal split of pair-transition peaks under the asymmetric bias; (iii) The\nimprovement of bath-temperature can enhance the phonon-emission\n(absorption)-assisted sequential tunneling and also strengthen the signals of\ninelastic pair-transition under the asymmetric bias; (iv) The inelastic\ndynamics driven by the ramp-up time-dependent voltage presents clear steps\nwhich can be tailored by the duration-time and bath-temperature; (v) The\nlinear-response spectrum obtained from the linear-response theory in the\nLiouville space reveals the excitation signals of electrons' dynamical\ntransition. Briefly, the physics caused by attraction mechanism stems from the\ndouble-occupancy or vacant-occupation of impurity system",
        "positive": "Conductance distribution in 3D Anderson insulators: deviation from\n  log-normal form: We show how a recent proposal to obtain the distribution of conductances in\nthree dimensions (3D) from a generalized Fokker-Planck equation for the joint\nprobability distribution of the transmission eigenvalues can be implemented for\nall strengths of disorder by numerically evaluating certain correlations of\ntransfer matrices. We then use this method to obtain analytically, for the\nfirst time, the 3D conductance distribution in the insulating regime and\nprovide a simple understanding of why it differs qualitatively from the\nlog-normal distribution of a quasi one-dimensional wire."
    },
    {
        "anchor": "Observation of collapse of pseudospin order in bilayer quantum Hall\n  ferromagnets: The Hartree-Fock paradigm of bilayer quantum Hall states with finite\ntunneling at filling factor $\\nu$=1 has full pseudospin ferromagnetic order\nwith all the electrons in the lowest symmetric Landau level. Inelastic light\nscattering measurements of low energy spin excitations reveal major departures\nfrom the paradigm at relatively large tunneling gaps. The results indicate the\nemergence of a novel correlated quantum Hall state at $\\nu$=1 characterized by\nreduced pseudospin order. Marked anomalies occur in spin excitations when\npseudospin polarization collapses by application of in-plane magnetic fields.",
        "positive": "Large magnetoresistance in an electric field controlled\n  antiferromagnetic tunnel junction: Large magnetoresistance effect controlled by electric field rather than\nmagnetic field or electric current is a preferable routine for designing low\npower consumption magnetoresistance-based spintronic devices. Here we propose\nan electric-field controlled antiferromagnetic (AFM) tunnel junction with\nstructure of piezoelectric substrate/Mn3Pt/SrTiO3/Pt operating by the magnetic\nphase transition (MPT) of antiferromagnet Mn3Pt through its magneto-volume\neffect. The transport properties of the proposed AFM tunnel junction have been\ninvestigated by employing first-principles calculations. Our results show that\na magnetoresistance over hundreds of percent is achievable when Mn3Pt undergoes\nMPT from a collinear AFM state to a non-collinear AFM state. Band structure\nanalysis based on density functional calculations shows that the large TMR can\nbe attributed to the joint effect of significant different Fermi surface of\nMn3Pt at two AFM phases and the band symmetry filtering effect of the SrTiO3\ntunnel barrier. In addition, other than single-crystalline tunnel barrier, we\nalso discuss the robustness of the proposed magnetoresistance effect by\nconsidering amorphous AlOx barrier. Our results may open perspective way for\neffectively electrical writing and reading of the AFM state and its application\nin energy efficient magnetic memory devices."
    },
    {
        "anchor": "Non-local control of spin-spin correlation in finite geometry helical\n  edge: An infinite edge of a quantum Hall system prohibits indirect exchange\ncoupling between two spins whereas a quantum spin-Hall edge prohibits\nout-of-plane coupling. In this study we analyze an unexpected breakdown of this\nbehaviors in a finite system, where the two spins can interact also via a\nlonger path that traverses the whole perimeter of the system. We explain this\nusing an analytical model as well as using tight binding models in real space.\nBased on this finding, we propose how using a lead far away from the spins can\nswitch the coupling on and off among them non-locally.",
        "positive": "Modulation of electronic and mechanical properties of phosphorene\n  through strain: We report a first-principles study on the elastic, vibrational, and\nelectronic properties of recently synthesized phosphorene. By calculating\nGr\\\"uneisen parameters, we evaluate the frequency shift of Raman/infrared\nactive modes via symmetric biaxial strain. We also study an inducing\nsemiconductor-metal transition, the gap size, and effective mass of carriers in\nvarious strain configurations. Furthermore, we unfold the emergence of a\npeculiar Dirac-shaped dispersion for specific strain conditions, including the\nzigzag-oriented tensile strain. The observed linear energy spectrum has\ndistinct velocities corresponding to each of its linear branches and is limited\nto the $\\Gamma-X$ direction in the first Brillouin zone."
    },
    {
        "anchor": "Mechanism of electron localization in a quantum wire: We show that quasi-bound electron states are formed in a quantum wire as a\nresult of electron backscattering in the transition regions between the wire\nand the electron reservoirs, to which the wire is coupled. The backscattering\nmechanism is caused by electron density oscillations arising even in smooth\ntransitions due to the reflection of electrons not transmitting through the\nwire. The quasi-bound states reveal themselves in resonances of the electron\ntransmission probability through the wire. The calculations were carried out\nwithin the Hartree-Fock approximation using quasiclassic wavefunctions.",
        "positive": "Conductance through Quantum Dots Studied by Finite Temperature DMRG: With the Finite temperature Density Matrix Renormalization Group method\n(FT-DMRG), we depeloped a method to calculate thermo-dynamical quantities and\nthe conductance of a quantum dot system. Conductance is written by the local\ndensity of states on the dot. The density of states is calculated with the\nnumerical analytic continuation from the thermal Green's function which is\nobtained directly from the FT-DMRG. Typical Kondo behaviors in the quantum dot\nsystem are observed conveniently by comparing the conductance with the magnetic\nand charge susceptibilities: Coulomb oscillation peaks and the unitarity limit.\nWe discuss advantage of this method compared with others."
    },
    {
        "anchor": "Many-body fermionic excitations in Weyl semimetals due to elastic gauge\n  fields: We study the single-particle spectrum of three-dimensional Weyl semimetals\ntaking into account electron-phonon interactions that are the result of\nstraining the material. We find that a well-defined fermionic excitation\nappears in addition to the standard peak corresponding to quasiparticle states\nas suggested by Landau-Fermi liquid theory. Contrary to the case of Dirac\nsystems interacting via the Coulomb interaction, these satellite peaks appear\neven at lowest order in perturbation theory. The new excitations are\nanisotropic, as opposed to the single-particle spectrum, and their behavior is\ndictated by the Debye frequency, which naturally regulates the electron-phonon\ncoupling.",
        "positive": "Near-Field Thermal Energy Conversion by Tunneling to a Waveguide: Energy is a vital resource and hence there is a continuous strive to improve\nupon existing technologies and to find new ones that address that basic need.\nThe conversion of thermal energy is the primary method of generating electrical\nenergy from a broad range of sources, for example fossil fuels, solar thermal,\ngeothermal, and nuclear energy. A common need in all cases is the ability to\nefficiently extract the generated electromagnetic and thermal energy and to\nconvert it to electricity. The current methods of thermal energy extraction are\nbased on heat engines, thermoelectric and thermophotovoltaic conversion\nsystems. In this report a method based on the direct extraction of\nElectromagnetic energy from the thermal near-field through tunneling and\nsubsequent waveguiding, is presented."
    },
    {
        "anchor": "Acoustic Rashba-Edelstein effect: We theoretically study the mechanical induction of the spin density via the\nRashba spin--orbit interaction (SOI). The spin density in the linear response\nto lattice distortion dynamics is calculated based on the microscopic theory.\nWe reveal that there are two mechanisms of spin induction: one is the acoustic\nEdelstein effect (AEE) from the acceleration of the lattice dynamics and the\nother is caused by the Rashba spin--vorticity coupling (RSVC). We find that the\nAEE induces a more efficient spin-to-charge conversion in comparison with the\nconventional electric Edelstein effect. The induced spin density due to the\nRSVC is expressed as a Berry curvature-like quantity; therefore, it can be\nattributed to the spatial symmetry breaking due to the Rashba SOI. Our work\ndemonstrates high-efficiency spin generation in Rashba systems.",
        "positive": "Heat exchange between two interacting nanoparticles beyond the\n  fluctuation-dissipation regime: We show that the observed non-monotonic behavior of the thermal conductance\nbetween two nanoparticles when they are brought into contact is originated by\nan intricate phase space dynamics. Here it is assumed that this dynamics\nresults from the thermally activated jumping through a rough energy landscape.\nA hierarchy of relaxation times plays the key role in the description of this\ncomplex phase space behaviour. Our theory enables us to analyze the heat\ntransfer just before and at the moment of contact."
    },
    {
        "anchor": "The Discrete Noise of Magnons: Magnonics is a rapidly developing subfield of spintronics, which deals with\ndevices and circuits that utilize spin currents carried by magnons - quanta of\nspin waves. Magnon current, i.e. spin waves, can be used for information\nprocessing, sensing, and other applications. A possibility of using the\namplitude and phase of magnons for sending signals via electrical insulators\ncreates conditions for avoiding Ohmic losses, and achieving ultra-low power\ndissipation. Most of the envisioned magnonic logic devices are based on spin\nwave interference, where the minimum energy per operation is limited by the\nnoise level. The sensitivity and selectivity of magnonic sensors is also\nlimited by the low frequency noise. However, the fundamental question \"do\nmagnons make noise?\" has not been answered yet. It is not known how noisy\nmagnonic devices are compared to their electronic counterparts. Here we show\nthat the low-frequency noise of magnonic devices is dominated by the random\ntelegraph signal noise rather than 1/f noise - a striking contrast to\nelectronic devices (f is a frequency). We found that the noise level of surface\nmagnons depends strongly on the power level, increasing sharply at the on-set\nof nonlinear dissipation. The presence of the random telegraph signal noise\nindicates that the current fluctuations involve random discrete macro events.\nWe anticipate that our results will help in developing the next generation of\nmagnonic devices for information processing and sensing.",
        "positive": "Non-equilibrum dynamics in the strongly excited inhomogeneous Dicke\n  model: Using the exact eigenstates of the inhomogeneous Dicke model obtained by\nnumerically solving the Bethe equations, we study the decay of bosonic\nexcitations due to the coupling of the mode to an ensemble of two-level (spin\n1/2) systems. We compare the quantum time-evolution of the bosonic mode\npopulation with the mean field description which, for a few bosons agree up to\na relatively long Ehrenfest time. We demonstrate that additional excitations\nlead to a dramatic shortening of the period of validity of the mean field\nanalysis. However, even in the limit where the number of bosons equal the\nnumber of spins, the initial instability remains adequately described by the\nmean-field approach leading to a finite, albeit short, Ehrenfest time. Through\nfinite size analysis, we also present indications that the mean field approach\ncould still provide an adequate description for thermodynamically large systems\neven at long times. However, for mesoscopic systems one cannot expect it to\ncapture the behavior beyond the initial decay stage in the limit of an\nextremely large number of excitations."
    },
    {
        "anchor": "Phonon induced Superconductivity of High Temperatures in Electrical\n  Graphene Superlattices: We discuss the BCS theory for electrons in graphene with a superimposed\nelectrical unidirectional superlattice potential (SL). New Dirac points emerge\ntogether with van Hove singularities (VHS) linking them. We obtain a\nsuperconducting transition temperature $ T_c $ for chemical potentials close to\nthe VHS assuming that acoustic phonon coupling should be the dominant\nmechanism. Pairing of two onsite electrons with one electron close to the $\n{\\bf K} $ and the other close to the $ -{\\bf K} $ point is the most stable pair\nformation. The resulting order parameter is almost constant over the entire SL.",
        "positive": "Multiple Coupling of Topological Coherent Modes of Trapped Atoms: The possibility of generating multiple coherent modes in trapped Bose gases\nis advanced. This requires the usage of several driving fields whose\nfrequencies are tuned close to the corresponding transition frequencies. A\ngeneral criterion is derived explaining when the driving fields, even being in\nperfect resonance, cannot generate the topological coherent modes. This\ncriterion is termed the theorem of shape conservation. Bose-Einstein\ncondensates with generated coherent modes display a number of interesting\neffects, such as: interference fringes, interference current, mode locking,\ndynamic transition, critical phenomena, chaotic motion, harmonic generation,\nparametric conversion, atomic squeezing, and entanglement production.\nApproximate solutions, based on the averaging techniques, are found to be in\ngood agreement with direct numerical calculations for the Gross-Pitaevskii\nequation."
    },
    {
        "anchor": "Aharonov-Bohm magnetism and Landau diamagnetism in semimetals: We compute the magnetic response of hollow semimetal cylinders and rings to\nthe presence of an axial Aharonov-Bohm magnetic flux, in the absence of\ninteractions. We predict nullification of the Aharonov-Bohm effect for a class\nof dispersion laws that includes \"non-relativistic\" dispersion and demonstrate\nthat at zero flux the ground-state of a very short \"armchair\" graphene tube\nwill exhibit a ferromagnetic broken symmetry. We also compute the diamagnetic\nresponse of bulk semimetals to the presence of a uniform magnetic field,\nspecifically predicting that the susceptibility has a logarithmic dependence on\nthe size of the sample.",
        "positive": "Phonon Localization in Heat Conduction: Departures in phonon heat conduction from diffusion have been extensively\nobserved in nanostructures through their thermal conductivity reduction and\nlargely explained with classical size effects neglecting phonon's wave nature.\nHere, we report localization-behavior in phonon heat conduction due to multiple\nscattering and interference of phonon waves, observed through measurements of\nthe thermal conductivities of GaAs/AlAs superlattices with ErAs nanodots\nrandomly distributed at the interfaces. Near room temperature, the measured\nthermal conductivities increased with increasing number of SL periods and\neventually saturated, indicating a transition from ballistic-to-diffusive\ntransport. At low temperatures, the thermal conductivities of the samples with\nErAs dots first increased and then decreased with an increasing number of\nperiods, signaling phonon wave localization. This Anderson localization\nbehavior is also validated via atomistic Green's function simulations. The\nobservation of phonon localization in heat conduction is surprising due to the\nbroadband nature of thermal transport. This discovery suggests a new path\nforward for engineering phonon thermal transport."
    },
    {
        "anchor": "BN/Graphene/BN Transistors for RF Applications: In this letter, we demonstrate the first BN/Graphene/BN field effect\ntransistor for RF applications. The BN/Graphene/BN structure can preserve the\nhigh mobility of graphene, even when it is sandwiched between a substrate and a\ngate dielectric. Field effect transistors (FETs) using a bilayer graphene\nchannel have been fabricated with a gate length LG=450 nm. A current density in\nexcess of 1 A/mm and DC transconductance close to 250 mS/mm are achieved for\nboth electron and hole conductions. RF characterization is performed for the\nfirst time on this device structure, giving a current-gain cut-off frequency\nfT=33 GHz and an fT.LG product of 15 GHz.um. The improved performance obtained\nby the BN/Graphene/BN structure is very promising to enable the next generation\nof high frequency graphene RF electronics.",
        "positive": "Coulomb Blockade Fluctuations in Disordered Quantum Dots: We discuss some recent results on the statistics of the Coulomb Blockade in\ndisordered quantum dots containing spinless interacting fermions using the\nself-consistent Hartree-Fock approximation. We concentrate on the regime r_s\n>~1, with finite dimensionless conductance g. We present significantly\ndifferent results for the cases of a Coulomb and a nearest-neighbour bare\ninteraction. We show that neglecting rearrangements when the particle number is\nchanged (Koopmans' approximation) can lead to large errors, and show how the\nspectral statistics of the self-consistent single particle orbitals evolve with\nthe interaction strength."
    },
    {
        "anchor": "A Tunable Anomalous Hall Effect in a Non-Ferromagnetic System: We measure the low-field Hall resistivity of a magnetically-doped\ntwo-dimensional electron gas as a function of temperature and\nelectrically-gated carrier density. Comparing these results with the carrier\ndensity extracted from Shubnikov-de Haas oscillations reveals an excess Hall\nresistivity that increases with decreasing temperature. This excess Hall\nresistivity qualitatively tracks the paramagnetic polarization of the sample,\nin analogy to the ferromagnetic anomalous Hall effect. The data are consistent\nwith skew-scattering of carriers by disorder near the crossover to\nlocalization.",
        "positive": "Thermoelectric effects in Kondo correlated quantum dots: In this Letter we study thermoelectric effects in ultra small quantum dots.\nWe study the behaviour of the thermopower, Peltier coefficient and thermal\nconductance both in the sequencial tunneling regime and in the regime where\nKondo correlations develope. Both cases of linear response and non-equilibrium\ninduced by strong temperature gradients are considered. The thermopower is a\nvery sensitive tool to detect Kondo correlations. It changes sign both as a\nfunction of temperature and temperature gradient. We also discuss violations of\nthe Wiedemann-Franz law."
    },
    {
        "anchor": "A phonon laser utilizing quantum-dot spin states: We propose a nano-scale realization of a phonon laser utilizing\nphonon-assisted spin flips in quantum dots to amplify sound. Owing to a long\nspin relaxation time, the device can be operated in a strong pumping regime, in\nwhich the population inversion is close to its maximal value allowed under\nFermi statistics. In this regime, the threshold for stimulated emission is\nunaffected by spontaneous spin flips. Considering a nanowire with quantum dots\ndefined along its length, we show that a further improvement arises from\nconfining the phonons to one dimension, and thus reducing the number of phonon\nmodes available for spontaneous emission. Our work calls for the development of\nnanowire-based, high-finesse phonon resonators.",
        "positive": "Symmetry Enforced Chiral Hinge States and Surface Quantum Anomalous Hall\n  Effect in Magnetic Axion Insulator $\\text{Bi}_{2-x}\\text{Sm}_x\\text{Se}_3$: A universal mechanism to generate chiral hinge states in the ferromagnetic\naxion insulator phase is proposed, which leads to an exotic transport\nphenomena, the quantum anomalous Hall effect (QAHE) on some particular surfaces\ndetermined by both the crystalline symmetry and the magnetization direction. A\nrealistic material system Sm doped $\\text{Bi}_2\\text{Se}_3$ is then proposed to\nrealize such exotic hinge states by combing the first principle calculations\nand the Green's function techniques. A physically accessible way to manipulate\nthe surface QAHE is also proposed, which makes it very different from the QAHE\nin ordinary 2D systems."
    },
    {
        "anchor": "Hot carrier dynamics in a dispersionless plasmonic system: Hot carrier dynamics in a dispersionless plasmonic structures over a broad\nwavelength are studied by pump-probe measurements with 45 fs time resolution.\nThe role of direct excited as well as plasmon generated hot carriers on low\nenergy probe plasmons are studied by simultaneous measurement of differential\ntransmittance and reflectance. While the pump fluence dependence on the decay\ntimes is linear for hot electrons and plasmon generated hot electrons, when\npump is near resonant with the X- symmetry point, decay time varied as square\nof pump fluence. Decay times of 800 nm degenerate pump-probe measurements\nhighlight the difference in surface (reflection) and the bulk (transmission)\nmechanisms. Decay time corresponding to the hot carrier relaxation is in the 1\n-3 ps range for different excitation energies. Rise time, governed by the\nplasmon to hot carrier conversion and electron - electron scattering processes,\nis about 200 fs for the hot carrier and hot plasmon excitation cases which\nincreased to about 485 fs for when pump is resonant with interband transition\nat X- symmetry point.",
        "positive": "Electrostatic potential shape of gate defined quantum point contacts: Quantum point contacts (QPC) are fundamental building blocks of\nnanoelectronic circuits. For their emission dynamics as well as for interaction\neffects such as the 0.7-anomaly the details of the electrostatic potential are\nimportant, but the precise potential shapes are usually unknown. Here, we\nmeasure the one-dimensional subband spacings of various QPCs as a function of\ntheir conductance and compare our findings with models of lateral parabolic\nversus hard wall confinement. We find that a gate-defined QPC near pinch-off is\ncompatible with the parabolic saddle point scenario. However, as the number of\npopulated subbands is increased Coulomb screening flattens the potential bottom\nand a description in terms of a finite hard wall potential becomes more\nrealistic."
    },
    {
        "anchor": "Correspondence between Andreev reflection and Klein tunneling in bipolar\n  graphene: Andreev reflection at a superconductor and Klein tunneling through an n-p\njunction in graphene are two processes that couple electrons to holes -- the\nformer through the superconducting pair potential Delta and the latter through\nthe electrostatic potential U. We derive that the energy spectra in the two\nsystems are identical, at low energies E<<Delta and for an antisymmetric\npotential profile U(-x,y)=-U(x,y). This correspondence implies that bipolar\njunctions in graphene may have zero density of states at the Fermi level and\ncarry a current in equilibrium, analogously to superconducting Josephson\njunctions. It also implies that nonelectronic systems with the same band\nstructure as graphene, such as honeycomb-lattice photonic crystals, can exhibit\npseudo-superconducting behavior.",
        "positive": "Dynamical construction of Quadrupolar and Octupolar topological\n  superconductors: We propose a three-step periodic drive protocol to engineer\ntwo-dimensional~(2D) Floquet quadrupole superconductors and\nthree-dimensional~(3D) Floquet octupole superconductors hosting\nzero-dimensional Majorana corner modes~(MCMs), based on unconventional $d$-wave\nsuperconductivity. Remarkably, the driven system conceives four phases with\nonly $0$ MCMs, no MCMs, only anomalous $\\pi$ MCMs, and both regular $0$ and\nanomalous $\\pi$ MCMs. To circumvent the subtle issue of characterizing $0$ and\n$\\pi$ MCMs separately, we employ the periodized evolution operator to architect\nthe dynamical invariants, namely quadrupole and octupole motion in 2D and 3D,\nrespectively, that can distinguish different higher order topological phases\nunambiguously.Our study paves the way for the realization of dynamical\nquadrupolar and octupolar topological superconductors."
    },
    {
        "anchor": "Exciting high-frequency short-wavelength spin waves using high harmonics\n  of a magnonic cavity mode: Confined spin-wave modes are a promising object for studying nonlinear\neffects and future quantum technologies. Here, using micromagnetic simulations,\nwe use a microwave magnetic field from a coplanar waveguide (CPW) to pump a\nstanding spin-wave confined in the cavity of magnonic crystal. We find that the\nfrequency of the fundamental cavity mode is equal to the ferromagnetic\nresonance frequency of the plane film and overlaps with the magnonic bandgap,\nallowing high magnetic field tunability. Multi-frequency harmonics of the\ncavity mode are generated once the microwave amplitude surpasses a certain\nthreshold. Specifically, the second and third harmonics at 0.5 T equate to 48.6\nand 72.9 GHz with wavelengths of 44 and 22 nm respectively, which propagate\ninto the crystal. This effect reaches saturation when the CPW covers the entire\ncavity, making the system feasible for realization. These processes show\npotential for the advancement of magnonics at high-frequencies and very\nshort-wavelengths.",
        "positive": "Coherent magnon-induced domain wall motion in a magnetic insulator\n  channel: Advancing the development of spin-wave devices requires high-quality\nlow-damping magnetic materials where magnon spin currents can propagate\nefficiently and interact effectively with local magnetic textures. We show that\nmagnetic domain walls (DW) can modulate spin-wave transport in perpendicularly\nmagnetized channels of Bi-doped yttrium-iron-garnet (BiYIG). Conversely, we\ndemonstrate that the magnon spin current can drive DW motion in the BiYIG\nchannel device by means of magnon spin-transfer torque. The DW can be reliably\nmoved over 15 um distances at zero applied magnetic field by a magnon spin\ncurrent excited by an RF pulse as short as 1 ns. The required energy for\ndriving DW motion is orders of magnitude smaller than those reported for\nmetallic systems. These results facilitate low-switching-energy magnonic\ndevices and circuits where magnetic domains can be efficiently reconfigured by\nmagnon spin currents flowing within magnetic channels."
    },
    {
        "anchor": "Aharonov-Bohm Effect in Three-dimensional Higher-order Topological\n  Insulator: Hinge states are the hallmark of the 3D higher-order topological\ninsulator(HOTI). Here, we show that chiral hinge states can be identified by\nthe magnetic field induced Aharonov-Bohm(AB) oscillation of the electron\nconductance in the interferometer constructed by HOTI and normal metal. Unlike\nAB interferometer of 3D topological insulator(TI), we find that there are\ndifferent AB oscillation frequencies for a given direction of magnetic field in\n3D HOTI. And the oscillation frequencies are also strongly depending on the\ndirection of magnetic field. The main conclusion in our work is that there\nexists a universal linear relation between different oscillation frequencies.\nHere, by constructing an interference model of hinge states loops, we show both\nanalytically and numerically that the linear relation is fulfilled in the HOTI\neffective model. The four basic frequencies in the work are labeled as\n$\\omega_x$, $\\omega_y$, $\\omega_{x+y}$, $\\omega_{x-y}$ and the main linear\nrelations we demonstrate here are $\\omega_{x\\pm y}=\\omega_x \\pm \\omega_y$.\nThese results provide an effective way for the identification of the chiral\nhinge states, and the oscillation signatures are stable with different sample\nsize and bias.",
        "positive": "Ultra-nonlocality in density functional theory for photo-emission\n  spectroscopy: We derive an exact expression for the photo-current of photo-emission\nspectroscopy using time-dependent current density functional theory (TDCDFT).\nThis expression is given as an integral over the Kohn-Sham spectral function\nrenormalized by effective potentials that depend on the exchange-correlation\nkernel of current density functional theory. We analyze in detail the physical\ncontent of this expression by making a connection between the\ndensity-functional expression and the diagrammatic expansion of the\nphoto-current within many-body perturbation theory. We further demonstrate that\nthe density functional expression does not provide us with information on the\nkinetic energy distribution of the photo-electrons. Such information can, in\nprinciple, be obtained from TDCDFT by exactly modeling the experiment in which\nthe photo-current is split into energy contributions by means of an external\nelectromagnetic field outside the sample, as is done in standard detectors. We\nfind, however, that this procedure produces very nonlocal correlations between\nthe exchange-correlation fields in the sample and the detector."
    },
    {
        "anchor": "Analysis of Shot Noise at Finite Temperatures in Fractional Quantum Hall\n  Edge States: We investigate shot noise at {\\it finite temperatures} induced by the\nquasi-particle tunneling between fractional quantum Hall (FQH) edge states. The\nresulting Fano factor has the peak structure at a certain bias voltage. Such a\nstructure indicates that quasi-particles are weakly {\\it glued} due to thermal\nfluctuation. We show that the effect makes it possible to probe the difference\nof statistics between $\\nu=1/5,{}2/5$ FQH states where quasi-particles have the\nsame unit charge.Finally we propose a way to indirectly obtain statistical\nangle in hierarchical FQH states.",
        "positive": "Imaging Transport Resonances in the Quantum Hall Effect: We use a scanning capacitance probe to image transport in the quantum Hall\nsystem. Applying a DC bias voltage to the tip induces a ring-shaped\nincompressible strip (IS) in the 2D electron system (2DES) that moves with the\ntip. At certain tip positions, short-range disorder in the 2DES creates a\nquantum dot island in the IS. These islands enable resonant tunneling across\nthe IS, enhancing its conductance by more than four orders of magnitude. The\nimages provide a quantitative measure of disorder and suggest resonant\ntunneling as the primary mechanism for transport across ISs."
    },
    {
        "anchor": "Conductance Peak Distributions in Quantum Dots at Finite Temperature:\n  Signatures of the Charging Energy: We derive the finite temperature conductance peak distributions and\npeak-to-peak correlations for quantum dots in the Coulomb blockade regime\nassuming the validity of random matrix theory. The distributions are universal,\ndepending only on the symmetry class and the temperature measured in units of\nthe mean level spacing, $\\Delta$. When the temperature is comparable to\n$\\Delta$ several resonances contribute to the same conductance peak and we find\nsignificant deviations from the previously known $T \\ll \\Delta$ distributions.\nIn contrast to the $T \\ll \\Delta$ case, these distributions show a strong\nsignature of the charging energy and charge quantization on the dot.",
        "positive": "Large nonreciprocal absorption and emission of radiation in type-I Weyl\n  semimetals with time reversal symmetry breaking: The equality between the spectral, directional emittance and absorptance of\nan object under local thermal equilibrium is known as Kirchhoff's law of\nradiation. The breakdown of Kirchhoff's law of radiation is physically allowed\nby breaking time reversal symmetry and can open opportunities for nonreciprocal\nlight emitters and absorbers. Large anomalous Hall conductivity and angle\nrecently observed in topological Weyl semimetals, particularly type-I magnetic\nWeyl semimetals and type-II Weyl semimetals, are expected to create large\nnonreciprocal electromagnetic wave propagation. In this work, we focus on\ntype-I magnetic Weyl semimetals and show via modeling and simulation that\nnonreciprocal surface plasmons polaritons can result in pronounced\nnonreciprocity without an external magnetic field. The modeling in this work\nbegins with a single pair of Weyl nodes, followed by a more realistic model\nwith multiple paired Weyl nodes. Fermi-arc surface states are also taken into\naccount through the surface conductivity. This work points to the promising\napplicability of topological Weyl semimetals for magneto-optical and energy\napplications."
    },
    {
        "anchor": "Generation of higher-order topological insulators using periodic driving: Topological insulators~(TIs) are a new class of materials that resemble\nordinary band insulators in terms of a bulk band gap but exhibit protected\nmetallic states on their boundaries. In this modern direction, higher-order\nTIs~(HOTIs) are a new class of TIs in dimensions $d>1$. These HOTIs possess $(d\n- 1)$-dimensional boundaries that, unlike those of conventional TIs, do not\nconduct via gapless states but are themselves TIs. Precisely, an $n^{\\rm th}$\norder $d$-dimensional higher-order topological insulator is characterized by\nthe presence of boundary modes that reside on its $d_c=(d-n)$-dimensional\nboundary. For instance, a three-dimensional second (third) order TI hosts\ngapless (localized) modes on the hinges (corners), characterized by $d_c = 1\n(0)$. Similarly, a second-order TI in two dimensions only has localized corner\nstates ($d_c = 0$). These higher-order phases are protected by various\ncrystalline as well as discrete symmetries. The non-equilibrium tunability of\nthe topological phase has been a major academic challenge where periodic\nFloquet drive provides us golden opportunity to overcome that barrier. Here, we\ndiscuss different periodic driving protocols to generate Floquet higher-order\nTIs while starting from a non-topological or first-order topological phase.\nFurthermore, we emphasize that one can generate the dynamical anomalous\n$\\pi$-modes along with the concomitant $0$-modes. The former can be realized\nonly in a dynamical setup. We exemplify the Floquet higher-order topological\nmodes in two and three dimensions in a systematic way. Especially, in two\ndimensions, we demonstrate a Floquet second-order TI hosting $0$- and $\\pi$\ncorner modes. Whereas a three-dimensional Floquet second-order TI and Floquet\nthird-order TI manifest one- and zero-dimensional hinge and corner modes,\nrespectively.",
        "positive": "Quantum transport simulation of non-local response in Weyl semimetals: We numerically study the non-local transport signature in Weyl semimetal as a\ntest for interconnectedness of the surface states, using a recursive Green's\nfunction method. We drive a current using two leads connected on the same\nsurface (top surface) and apply a magnetic field throughout the system,\nperpendicular to the surface. We find that this results in a current flowing on\nthe other surface in the direction opposite to the direction of the current on\nthe top surface and we comment on the viability of observing such an effect in\nexperiment. The recursive Green's function method we employ is exact and\nprovides us with the Green's functions of the two surfaces as well as their\nconnecting elements, which can be applied also for other numerical simulations\nwhere the effect of surface to surface transport is important."
    },
    {
        "anchor": "Memory effects in complex materials and nanoscale systems: Memory effects are ubiquitous in nature and are particularly relevant at the\nnanoscale where the dynamical properties of electrons and ions strongly depend\non the history of the system, at least within certain time scales. We review\nhere the memory properties of various materials and systems which appear most\nstrikingly in their non-trivial time-dependent resistive, capacitative and\ninductive characteristics. We describe these characteristics within the\nframework of memristors, memcapacitors and meminductors, namely memory circuit\nelements whose properties depend on the history and state of the system. We\nexamine basic issues related to such systems and critically report on both\ntheoretical and experimental progress in understanding their functionalities.\nWe also discuss possible applications of memory effects in various areas of\nscience and technology ranging from digital to analog electronics,\nbiologically-inspired circuits, and learning. We finally discuss future\nresearch opportunities in the field.",
        "positive": "Impurity State and Variable Range Hopping Conduction in Graphene: The variable range hopping theory, as formulated for exponentially localized\nimpurity states, does not necessarily apply in the case of graphene with\ncovalently attached impurities. We analyze the localization of impurity states\nin graphene using the nearest-neighbor, tight-binding model of an\nadatom-graphene system with Green's function perturbation methods. The\namplitude of the impurity state wave function is determined to decay as a power\nlaw with exponents depending on sublattice, direction, and the impurity\nspecies. We revisit the variable range hopping theory in view of this result\nand find that the conductivity depends as a power law of the temperature with\nan exponent related to the localization of the wave function. We show that this\ntemperature dependence is in agreement with available experimental results."
    },
    {
        "anchor": "Anisotropic ground states of the quantum Hall system with currents: Anisotropic states at half-filled third and higher Landau levels are\ninvestigated in the system with a finite electric current. We study the\nresponse of the striped Hall state and the anisotropic charge density wave\n(ACDW) state against the injected current using the effective action. Current\ndistributions and a current dependence of the total energy are determined for\nboth states. With no injected current, the energy of the ACDW state is lower\nthan that of the striped Hall state. We find that the energy of the ACDW state\nincreases faster than that of the striped Hall state as the injected current\nincreases. Hence, the striped Hall state becomes the lower energy state when\nthe current exceeds the critical value. The critical value is estimated at\nabout 0.04 - 0.05 nA which is much smaller than the current used in the\nexperiments. Our calculations are performed using a block diagonalization\ntechnique on a von Neumann lattice. We review this technique in this thesis.",
        "positive": "Dzyaloshinskii-Moriya spin density by skew scattering: Anisotropic exchange couplings, such as the Dzyaloshinskii-Moriya interaction\n(DMI), have played a vital role in the formation and dynamics of spin textures.\nThis work predicts an anisotropic conduction electron spin density in metals\nwith heavy magnetic impurities. The polarization of this\n$Dzyaloshinskii$-$Moriya$ $spin$ $density$ (DM-SD) is not collinear to the\nlocalized magnetic moments but rotated by the spin-dependent skew scattering of\nheavy atoms. The DM-SD induces the DMI between magnetic moments in metals and,\ntherefore, it is the anisotropic extension of the\nRutherman-Kittel-Kasuya-Yoshida spin density. Our model consists of two\nlocalized magnetic moments, one with a large spin-orbit coupling (a lanthanide\nor rare earth), in a free electron gas. The lanthanide spin controls the DM-SD\nstrength and polarization, promising a flexible control mechanism for\nanisotropic couplings."
    },
    {
        "anchor": "Room Temperature Electrical Detection of Spin Polarized Currents in\n  Topological Insulators: Topological insulators (TIs) are a new class of quantum materials that\nexhibit spin momentum locking (SML) of massless Dirac fermions in the surface\nstates. Usually optical methods, such as angle and spin-resolved photoemission\nspectroscopy, have been employed to observe the helical spin polarization in\nthe surface states of three-dimensional (3D) TIs up to room temperatures.\nRecently, spin polarized surface currents in 3D TIs were detected by electrical\nmethods using ferromagnetic (FM) contacts in a lateral spin-valve measurement\ngeometry. However, probing the spin texture with such electrical approaches is\nso far limited to temperatures below 125K, which restricts its application\npotential. Here we demonstrate the room temperature electrical detection of the\nspin polarization on the surface of Bi$_2$Se$_3$ due to SML by employing spin\nsensitive FM tunnel contacts. The current-induced spin polarization on the\nBi$_2$Se$_3$ surface is probed at room temperature by measuring a spin-valve\nsignal while switching the magnetization direction of the FM detector. The spin\nsignal increases linearly with current bias, reverses sign with current\ndirection, exhibits a weak temperature dependence and decreases with higher TI\nthickness, as predicted theoretically. Our results demonstrate the electrical\ndetection of the spin polarization on the surface of 3D TIs, which could lead\nto innovative spin-based quantum information technology at ambient\ntemperatures.",
        "positive": "Quantum noise and entanglement generated by a local quantum quench: We examine the growth of entanglement under a quantum quench at point\ncontacts of simple fractional quantum Hall fluids and its relation with the\nmeasurement of local observables. Recently Klich and Levitov proposed that the\nnoise generated from a local quantum quench provides a measure of the\nentanglement entropy. Their methods were specific to non-interacting electrons\nand the generalization to interacting systems was left as an open question. In\nthis work, we generalize their result to the Laughlin states. We investigate\nthe noise generated in the current along the edge of a fractional quantum Hall\nstate at filling factors $\\nu=1/m$, when a quantum point contact, initially\nclosed, is fully opened at some initial time $t_0=0$. We find that local\nquenching in these systems gives time dependent correlation functions that have\nuniversal behavior on sufficiently long time and length scales. We calculate\nthe noise and full counting statistics for $\\nu=1/m$ and find that in general,\nthe entanglement entropy and noise generated are unrelated quantities. We also\ndiscuss a generalization of this problem to the critical quantum Ising spin\nchain."
    },
    {
        "anchor": "Switching of +/-360deg domain wall states in a nanoring by an azimuthal\n  Oersted field: We demonstrate magnetic switching between two $360^\\circ$ domain wall vortex\nstates in cobalt nanorings, which are candidate magnetic states for robust and\nlow power MRAM devices. These $360^\\circ$ domain wall (DW) or \"twisted onion\"\nstates can have clockwise or counterclockwise circulation, the two states for\ndata storage. Reliable switching between the states is necessary for any\nrealistic device. We accomplish this switching by applying a circular Oersted\nfield created by passing current through a metal atomic force microscope tip\nplaced at the center of the ring. After initializing in an onion state, we\nrotate the DWs to one side of the ring by passing a current through the center,\nand can switch between the two twisted states by reversing the current, causing\nthe DWs to split and meet again on the opposite side of the ring. A larger\ncurrent will annihilate the DWs and create a perfect vortex state in the rings.",
        "positive": "Distribution of residence times as a marker to distinguish different\n  pathways for quantum transport: Electron transport through a nanoscale system is an inherently stochastic\nquantum mechanical process. Electric current is a time series of electron\ntunnelling events separated by random intervals. Thermal and quantum noise are\ntwo sources of this randomness. In this paper, we used the quantum master\nequation to consider the following questions: (i) Given that an electron has\ntunnelled into the electronically unoccupied system from the source electrode\nat some particular time, how long is it until an electron tunnels out to the\ndrain electrode to leave the system electronically unoccupied, where there were\nno intermediate tunnelling events (\"the\" tunnelling path)? (ii) Given that an\nelectron has tunnelled into the unoccupied system from the source electrode at\nsome particular time, how long is it until an electron tunnels out to the drain\nelectrode to leave the system electronically unoccupied, where there were no\nintermediate tunnelling events (\"an\" tunnelling path)? (iii) What are the\ndistributions of these times? We show that electron correlations suppress the\ndifference between \"the\" and \"an\" electron tunnelling paths."
    },
    {
        "anchor": "Electric-field-induced extremely large change in resistance in graphene\n  ferromagnets: A colossal magnetoresistance ($\\sim 100\\times10^3\\%$) and an extremely large\nmagnetoresistance ($\\sim 1\\times10^6\\%$) have been previously explored in\nmanganite perovskites and Dirac materials, respectively. However, the\nrequirement of an extremely strong magnetic field (and an extremely low\ntemperature) makes them not applicable for realistic devices. In this work, we\npropose a device that can generate even larger changes in resistance in a\nzero-magnetic field and at a high temperature. The device is composed of a\ngraphene under two strips of yttrium iron garnet (YIG), where two gate voltages\nare applied to cancel the heavy charge doping in the YIG-induced half-metallic\nferromagnets. By calculations using the Landauer-B\\\"{u}ttiker formalism, we\ndemonstrate that, when a proper gate voltage is applied on the free\nferromagnet, changes in resistance up to $305\\times10^6\\%$ ($16\\times10^3\\%$)\ncan be achieved at the liquid helium (nitrogen) temperature and in a zero\nmagnetic field. We attribute such a remarkable effect to a gate-induced\nfull-polarization reversal in the free ferromagnet, which results in a\nmetal-state to insulator-state transition in the device. We also find that, the\nproposed effect can be realized in devices using other magnetic insulators such\nas EuO and EuS. Our work should be helpful for developing a realistic switching\ndevice that is energy saving and CMOS-technology compatible.",
        "positive": "Disorder-enhanced transport in a chain of lossy dipoles strongly coupled\n  to cavity photons: We study the interplay between disorder and light-matter coupling by\nconsidering a disordered one-dimensional chain of lossy dipoles coupled to a\nmultimode optical cavity, through a microscopically derived Hamiltonian. Such a\nsystem, hosting polaritonic excitations, may be realized experimentally in a\nwide range of platforms under strong light-matter coupling. By analyzing both\nthe eigenspectrum and the driven-dissipative transport properties of our\nsystem, we find that in the strong-coupling regime, increasing disorder leads\nalmost uncoupled dark states to acquire a photonic part, allowing them to\ninherit polaritonic long-range transport characteristics. Crucially, we show\nthat this disorder-enhanced transport mechanism is increasingly noticeable when\nthe considered dipoles are lossier."
    },
    {
        "anchor": "Superlattice nonlinearities for Gigahertz-Terahertz generation in\n  harmonic multipliers: Semiconductor superlattices are strongly nonlinear media offering several\ntechnological challenges associated with the generation of high-frequency\nGigahertz radiation and very effective frequency multiplication up to several\nTerahertz. However, charge accumulation, traps and interface defects lead to\npronounced asymmetries in the nonlinear current flow, from which high harmonic\ngeneration stems. This problem requires a full non-perturbative solution of\nasymmetric current flow under irradiation, which we deliver in this paper\nwithin the Boltzmann-Bloch approach. We investigate the nonlinear output on\nboth frequency and time domains and demonstrate a significant enhancement of\neven harmonics by tuning the interface quality. Moreover, we find that\nincreasing arbitrarily the input power is not a solution for high nonlinear\noutput, in contrast with materials described by conventional susceptibilities.\nThere is a complex combination of asymmetry and power values leading to maximum\nhigh harmonic generation.",
        "positive": "Strong band-filling-dependence of the scattering lifetime in gated MoS2\n  nanolayers induced by the opening of intervalley scattering channels: Gated molybdenum disulphide (MoS2) exhibits a rich phase diagram upon\nincreasing electron doping, including a superconducting phase, a polaronic\nreconstruction of the bandstructure, and structural transitions away from the\n2H polytype. The average time between two charge-carrier scattering events -\nthe scattering lifetime - is a key parameter to describe charge transport and\nobtain physical insight in the behavior of such a complex system. In this work,\nwe combine the solution of the Boltzmann transport equation (based on ab-initio\ndensity functional theory calculations of the electronic bandstructure) with\nthe experimental results concerning the charge-carrier mobility, in order to\ndetermine the scattering lifetime in gated MoS2 nanolayers as a function of\nelectron doping and temperature. From these dependencies, we assess the major\nsources of charge-carrier scattering upon increasing band filling, and discover\ntwo narrow ranges of electron doping where the scattering lifetime is strongly\nsuppressed. We indentify the opening of additional intervalley scattering\nchannels connecting the simultaneously-filled K/K' and Q/Q' valleys in the\nBrillouin zone as the source of these reductions, which are triggered by the\ntwo Lifshitz transitions induced by the filling of the high-energy Q/Q' valleys\nupon increasing electron doping."
    },
    {
        "anchor": "New Physics in High Landau Levels: Recent magneto-transport experiments on ultra-high mobility 2D electron\nsystems in GaAs/AlGaAs heterostructures have revealed the existence of whole\nnew classes of correlated many-electron states in highly excited Landau levels.\nThese new states, which appear only at extremely low temperatures, are\ndistinctly different from the familiar fractional quantum Hall liquids of the\nlowest Landau level. Prominent among the recent findings are the discoveries of\ngiant anisotropies in the resistivity near half filling of the third and higher\nLandau levels and the observation of re- entrant integer quantum Hall states in\nthe flanks of these same levels. This contribution will survey the present\nstatus of this emerging field.",
        "positive": "Robust Flat Bands with Tunable Energies in Honeycomb Superlattices: Flat bands in lattice models have provided useful platforms for studying\nstrong correlation and topological physics. Recently, honeycomb superlattices\nhave been shown to host flat bands that persist in the presence of local\nperturbations respecting lattice symmetries. We analytically derive the flat\nband energies in the presence of longer range hopping and find that the\nenergies of flat bands are tunable by these perturbations. In real space, the\nwave function is constructed from standing waves on each honeycomb edge,\nallowing the construction of plaquette and loop eigenstates due to destructive\ninterference in real space that give rise to the flat bands robust against long\nrange hoppings."
    },
    {
        "anchor": "Quantum Transport with Spin Dephasing: A Nonequilibrium Green's Function\n  Approach: A quantum transport model incorporating spin scattering processes is\npresented using the non-equilibrium Green's function (NEGF) formalism within\nthe self-consistent Born approximation. This model offers a unified approach by\ncapturing the spin-flip scattering and the quantum effects simultaneously. A\nnumerical implementation of the model is illustrated for magnetic tunnel\njunction devices with embedded magnetic impurity layers. The results are\ncompared with experimental data, revealing the underlying physics of the\ncoherent and incoherent transport regimes. It is shown that small variations in\nmagnetic impurity spin-states/concentrations could cause large deviations in\njunction magnetoresistances.",
        "positive": "Quantum Spin-Valley Hall Kink States: From Concept to Materials Design: We propose a general and tunable platform to realize high-density arrays of\nquantum spin-valley Hall kink (QSVHK) states with spin-valley-momentum locking\nbased on a two-dimensional hexagonal topological insulator. Through the\nanalysis of Berry curvature and topological charge, the QSVHK states are found\nto be topologically protected by the valley-inversion and time-reversal\nsymmetries. Remarkably, the conductance of QSVHK states remains quantized\nagainst either nonmagnetic or long-range magnetic disorder, verified by the\nGreen function calculations. Based on first-principles results, we show that\nQSVHK states, protected with a gap up to 287 meV, can be realized in bismuthene\nby alloy engineering, surface functionalization, or electric field, supporting\nnon-volatile applications of spin-valley filters, valves, and waveguides even\nat room temperature."
    },
    {
        "anchor": "Non-divergent Chiral Charge Pumping in Weyl Semimetal: Recent studies suggest that the nonlinear transport properties in Weyl\nsemimetal may be a measurable consequence of its chiral anomaly. Nonlinear\nresponses in transport are estimated to be substantial, because in real\nmaterials such as TaAs or Bi$_{1-x}$Sb$_x$, the Fermi level resides near the\nWeyl nodes where the chiral charge pumping is said to diverge. However, this\nwork presents semiclassical Boltzmann analysis that indicates that the chiral\ncharge pumping is non-divergent even at the zero-temperature limit. We\ndemonstrate that the divergence in common semiclassical calculation scheme is\nnot a problem of the scheme itself, but occurs because a commonly-used\napproximation of the change in particle number breaks down near the Weyl nodes.\nOur result suggests the possibility that the nonlinear properties in WSMs can\nbe overestimated, and provides the validity condition for the conventional\napproximation. We also show the distinct Fermi level dependencies of the chiral\nmagnetic effect and the negative longitudinal magnetoresistance, as a\nconsequence of non-diverging chiral charge pumping.",
        "positive": "Magnetic domain walls in strain-patterned ultrathin films: We present a comparison of the characteristics of the magnetic domain walls\nin an atomic monolayer of Co on Pt(111) and a Ni/Fe atomic bilayer on Ir(111),\nbased on spin-polarized scanning tunneling microscopy measurements. In both\ncases, the films exhibit a roughly triangular dislocation line pattern created\nby epitaxial strain relief, as well as out-of-plane ferromagnetic order.\nDomains with opposite magnetization are separated by domain walls with a unique\nrotational sense, demonstrating the important role of the Dzyaloshinskii-Moriya\ninteraction induced by the Co/Pt and the Fe/Ir interfaces. The domain walls in\nCo/Pt(111) are straight and usually found in geometrical constrictions of the\nfilm, where they can minimize their length. In contrast, the domain walls in\nNi/Fe/Ir(111) follow complicated paths, which can be correlated to the\nstructural triangular pattern. The comparison between the two systems shows\nthat the structural patterns, despite their similarity, have a different impact\non the domain walls. In the Co/Pt(111) case, the magnetic state is not\ninfluenced by the dislocation line network, in contrast to the Ni/Fe/Ir(111)\nsystem in which the formation of the walls is favored at specific positions of\nthe structural pattern."
    },
    {
        "anchor": "Repeatable Room Temperature Negative Differential Conductance in GaN/AlN\n  Resonant Tunneling Diodes: Double barrier GaN/AlN resonant tunneling heterostructures have been grown by\nmolecular beam epitaxy on the (0001) plane of commercially available bulk GaN\nsubstrates. Resonant tunneling diodes were fabricated; room temperature\ncurrent-voltage measurements reveal the presence of a negative differential\nconductance region under forward bias with peak current densities of ~6.4\n$kA/cm^2$ and a peak to valley current ratio of ~1.3. Reverse bias operation\npresents a characteristic turn-on threshold voltage intimately linked to the\npolarization fields present in the heterostructure. An analytic electrostatic\nmodel is developed to capture the unique features of\npolar-heterostructure-based resonant tunneling diodes; both the resonant and\nthreshold voltages are derived as a function of the design parameters and\npolarization fields. Subsequent measurements confirm the repeatability of the\nnegative conductance and demonstrate that III-nitride tunneling\nheterostructures are capable of robust resonant transport at room temperature.",
        "positive": "Selective excitations of trasverse vibrational modes of a carbon\n  nanotube through a \"shuttle-like\" electromechanical instability: We study the dynamics of transverse oscillations of a suspended carbon\nnanotube into which current is injected from the tip of a scanning tunneling\nmicroscope (STM). In this case the correlations between the displacement of the\nnanotube and its charge state, determined by the position-dependent electron\ntunneling rate, can lead to a \"shuttle-like\" instability for the transverse\nvibrational modes. We find that selective excitation of a specific mode can be\nachieved by an accurate positioning of the STM tip. This result suggests a\nfeasible way to control the dynamics of this nano-electromechanical system\n(NEMS) based on the \"shuttle instability\"."
    },
    {
        "anchor": "Bloch Oscillations, Landau-Zener Transition, and Topological Phase\n  Evolution in a Pendula Array: We experimentally and theoretically study the dynamics of a one-dimensional\narray of pendula with a mild spatial gradient in their self-frequency and where\nneighboring pendula are connected with weak and alternating coupling. We map\ntheir dynamics to the topological Su-Schrieffer-Heeger (SSH) model of charged\nquantum particles on a lattice with alternating hopping rates in an external\nelectric field. By directly tracking the dynamics of a wavepacket in the bulk\nof the lattice, we observe Bloch oscillations, Landau-Zener transitions, and\ncoupling between the isospin (i.e. the inner wave function distribution within\nthe unit cell) and the spatial degrees of freedom (the distribution between\nunit cells). We then use Bloch oscillations in the bulk to directly measure the\nnon-trivial global topological phase winding and local geometric phase of the\nband. We measure an overall evolution of 3.1 $\\pm$ 0.2 radians for the\ngeometrical phase during the Bloch period, consistent with the expected Zak\nphase of $\\pi$. Our results demonstrate the power of classical analogs of\nquantum models to directly observe the topological properties of the band\nstructure, and sheds light on the similarities and the differences between\nquantum and classical topological effects.",
        "positive": "Broadband microwave detection using electron spins in a hybrid\n  diamond-magnet sensor chip: Quantum sensing has developed into a main branch of quantum science and\ntechnology. It aims at measuring physical quantities with high resolution,\nsensitivity, and dynamic range. Electron spins in diamond are powerful magnetic\nfield sensors, but their sensitivity in the microwave regime is limited to a\nnarrow band around their resonance frequency. Here, we realize broadband\nmicrowave detection using spins in diamond interfaced with a thin-film magnet.\nA pump field locally converts target microwave signals to the sensor-spin\nfrequency via the non-linear spin-wave dynamics of the magnet. Two\ncomplementary conversion protocols enable sensing and high-fidelity spin\ncontrol over a gigahertz bandwidth, allowing characterization of the spin-wave\nband at multiple gigahertz above the sensor-spin frequency. The pump-tunable,\nhybrid diamond-magnet sensor chip opens the way for spin-based sensing in the\n100-gigahertz regime at small magnetic bias fields."
    },
    {
        "anchor": "Skyrmion dynamics in chiral ferromagnets under spin-transfer torque: We study the dynamics of skyrmions under spin-transfer torque in\nDzyaloshinskii-Moriya materials with easy-axis anisotropy. In particular, we\nstudy the motion of a topological skyrmion with skyrmion number $Q=1$ and a\nnon-topological skyrmionium with $Q=0$ using their linear momentum, virial\nrelations, and numerical simulations. The non-topological $Q=0$ skyrmionium is\naccelerated in the direction of the current flow and it either reaches a steady\nstate with constant velocity, or it is elongated to infinity. The steady-state\nvelocity is given by a balance between current and dissipation and has an upper\nlimit. In contrast, the topological $Q=1$ skyrmion converges to a steady-state\nwith constant velocity at an angle to the current flow. When the spin current\nstops the $Q=1$ skyrmion is spontaneously pinned whereas the $Q=0$ skyrmionium\ncontinues propagation. Exact solutions for the propagating skyrmionium are\nidentified as solutions of equations given numerically in a previous work.\nFurther exact results for propagating skyrmions are given in the case of the\npure exchange model. The traveling solutions provide arguments that a\nspin-polarized current will cause rigid motion of a skyrmion or a skyrmionium.",
        "positive": "Effect of spin rotation coupling on spin transport: We have studied the spin rotation coupling(SRC) as an ingredient to explain\ndifferent spin related issues. This special kind of coupling can play the role\nof a Dresselhaus like coupling in certain conditions. Consequently, one can\ncontrol the spin splitting, induced by the Dresselhaus like term, which is\nunusual in semiconductor heterostucture. Within this framework, we also study\nthe renormalization of the spin dependent electric field and spin current due\nto the $\\vec{k} . \\vec{p}$ perturbation, by taking into account the interband\nmixing in the rotating system. In this paper we predict the enhancement of the\nspin dependent electric field resulting from the renormalized spin rotation\ncoupling. The renormalization factor of the spin electric field is different\nfrom that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin\ncurrent and Berry curvature is also studied. Interestingly, in presence of this\nSRC induced SOC it is possible to describe spin splitting as well as spin\ngalvanic effect in semiconductors."
    },
    {
        "anchor": "Collective resonances near zero energy induced by a point defect in\n  bilayer graphene: Intrinsic defects give rise to scattering processes governing the transport\nproperties of mesoscopic systems. We investigate analytically and numerically\nthe local density of states in Bernal stacking bilayer graphene with a point\ndefect. With Bernal stacking structure, there are two types of lattice sites.\nOne corresponds to connected sites, where carbon atoms from each layer stack on\ntop of each other, and the other corresponds to disconnected sites. From our\ntheoretical study, a picture emerges in which the pronounced zero-energy peak\nin the local density of states does not attribute to zero-energy impurity\nstates associated to two different types of defects but to a collective\nphenomenon of the low-energy resonant states induced by the defect. To\ncorroborate this description, we numerically show that at small system size\n$N$, where $N$ is the number of unit cells, the zero-energy peak near the\ndefect scales as $1/\\ln N$ for the quasi-localized zero-energy state and as\n$1/N$ for the delocalized zero-energy state. As the system size approaches to\nthe thermodynamic limit, the former zero-energy peak becomes a power-law\nsingularity $1/|E|$ in low energies, while the latter is broadened into a\nLorentzian shape. A striking point is that both types of zero-energy peaks\ndecay as $1/r^2$ away from the defect, manifesting the quasi-localized\ncharacter. Based on our results, we propose a general formula for the local\ndensity of states in low-energy and in real space. Our study sheds light on\nthis fundamental problem of defects.",
        "positive": "Conditional operation of a spin qubit: We report coherent operation of a singlet-triplet qubit controlled by the\narrangement of two electrons in an adjacent double quantum dot. The system we\ninvestigate consists of two pairs of capacitively coupled double quantum dots\nfabricated by electrostatic gates on the surface of a GaAs heterostructure. We\nextract the strength of the capacitive coupling between qubit and double\nquantum dot and show that the present geometry allows fast conditional gate\noperation, opening pathways to multi-qubit control and implementation of\nquantum algorithms with spin qubits."
    },
    {
        "anchor": "Tunable spin and transport in porphyrin-graphene nanoribbon hybrids: Recently, porphyrin units have been attached to graphene nanoribbons\n(Por-GNR) enabling a multitude of possible structures. Here we report first\nprinciples calculations of two prototypical, experimentally feasible, Por-GNR\nhybrids, one of which displays a small band gap relevant for its use as\nelectrode in a device. Embedding a Fe atom in the porphyrin causes spin\npolarization with a spin ground state $S=1$. We employ density functional\ntheory and nonequilibrium Green's function transport calculations to examine a\n2-terminal setup involving one Fe-Por-GNR between two metal-free, small band\ngap, Por-GNR electrodes. The coupling between the Fe-$d$ and GNR band states\nresults in a Fano anti-resonance feature in the spin transport close to the\nFermi energy. This feature makes transport highly sensitive to the Fe spin\nstate. We demonstrate how mechanical strain or chemical adsorption on the Fe\ngive rise to a spin-crossover to $S=1$ and $S=0$, respectively, directly\nreflected in a change in transport. Our theoretical results provide a clue for\nthe on-surface synthesis of Por-GNRs hybrids, which can open a new avenue for\ncarbon-based spintronics and chemical sensing.",
        "positive": "Anomalous Hall Effect in Layered Ferrimagnet MnSb2Te4: We report on low-temperature electron transport properties of MnSb2Te4, a\ncandidate of ferrimagnetic Weyl semimetal. Long -range magnetic order is\nmanifested as a nearly square-shaped hysteresis loop in the anomalous Hall\nresistance, as well as sharp jumps in the magnetoresistance. At temperatures\nbelow 4 K, a lnT-type upturn appears in the temperature dependence of\nlongitudinal resistance, which can be attributed to the electron-electron\ninteraction (EEI), since the weak localization can be excluded by the\ntemperature dependence of magnetoresistance. Although the anomalous Hall\nresistance exhibits a similar lnT-type upturn in the same temperature range,\nsuch correction is absent in the anomalous Hall conductivity. Our work\ndemonstrates that MnSb2Te4 microflakes provide an ideal system to test the\ntheory of EEI correction to the anomalous Hall effect."
    },
    {
        "anchor": "Recombination limited energy relaxation in a BCS superconductor: We study quasiparticle energy relaxation at sub-kelvin temperatures by\ninjecting hot electrons into an aluminium island and measuring the energy flux\nfrom electrons into phonons both in the superconducting and in the normal\nstate. The data show strong reduction of the flux at low temperatures in the\nsuperconducting state, in qualitative agreement with the presented\nquasiclassical theory for clean superconductors. Quantitatively, the energy\nflux exceeds that from the theory both in the superconducting and in the normal\nstate, possibly suggesting an enhanced or additional relaxation process.",
        "positive": "Cubic 3D Chern photonic insulators with orientable large Chern vectors: Time Reversal Symmetry (TRS) broken topological phases provide gapless\nsurface states protected by topology, regardless of additional internal\nsymmetries, spin or valley degrees of freedom. Despite the numerous\ndemonstrations of 2D topological phases, few examples of 3D topological systems\nwith TRS breaking exist. In this article, we devise a general strategy to\ndesign 3D Chern insulating (3D CI) cubic photonic crystals in a weakly TRS\nbroken environment with orientable and arbitrarly large Chern vectors. The\ndesigns display topologically protected chiral and unidirectional surface\nstates with disjoint equifrequency loops. The resulting crystals present the\nfollowing novel characteristics: First, by increasing the Chern number,\nmultiple surface states channels can be supported. Second, the Chern vector can\nbe oriented along any direction simply changing the magnetization axis, opening\nup larger 3D CI/3D CI interfacing possibilities as compared to 2D. Third, by\nlowering the TRS breaking requirements, the system is ideal for realistic\nphotonic applications where the magnetic response is weak."
    },
    {
        "anchor": "Renormalization of spin excitations and Kondo effect in open shell\n  nanographenes: We study spin excitations and Kondo effect in open-shell nanographenes,\nmotivated by recent scanning tunneling inelastic spectroscopy experiments.\nSpecifically, we consider three systems, the triangulene, the extended\ntriangulene with rocket shape, both with an $S=1$ ground state, and a\ntriangulene dimer with $S=0$ on account of intermolecular exchange. We focus on\nthe consequences of hybridization of the nanographene zero-modes with a\nconducting substrate on the $dI/dV$ lineshapes associated with spin\nexcitations. The partially filled nanographene zero-modes coupled to the\nconduction electrons in the substrate constitute multi-orbital Anderson\nimpurity models that we solve in the one-crossing approximation which treats\nthe coupling to the substrate to infinite order. We find that the coupling to\nthe substrate leads to (i) renormalization of the spin flip excitation energies\nof the bare molecule, (ii) broadening of the spectral features and (iii) the\nemergence of zero bias Kondo peaks for the $S=1$ ground states. The calculated\nsubstrate induced shift of the spin excitation energies is found to be\nsignificantly larger than their broadening, which implies that this effect has\nto be considered when comparing experimental results and theory.",
        "positive": "A Pathway between Bernal and Rhombohedral Stacked Graphene Layers with\n  Scanning Tunneling Microscopy: Horizontal shifts in the top layer of highly oriented pyrolytic graphite,\ninduced by a scanning tunneling microscope (STM) tip, are presented. Excellent\nagreement is found between STM images and those simulated using density\nfunctional theory. First-principle calculations identify that the low-energy\nbarrier direction of the top layer displacement is toward a structure where\nnone of the carbon pz orbitals overlap, while the high-energy barrier direction\nis toward AA stacking. Each directional shift yields a real-space surface\ncharge density similar to graphene; however the low-energy barrier direction\nrequires only one bond length to convert ABA (Bernal) to ABC (rhombohedral)."
    },
    {
        "anchor": "Second-Order Bulk-Boundary Correspondence in Rotationally Symmetric\n  Topological Superconductors from Stacked Dirac Hamiltonians: Two-dimensional second-order topological superconductors host\nzero-dimensional Majorana bound states at their boundaries. In this work,\nfocusing on rotation-invariant crystalline topological superconductors, we\nestablish a bulk-boundary correspondence linking the presence of such Majorana\nbound states to bulk topological invariants introduced by Benalcazar et al. We\nthus establish when a topological crystalline superconductor protected by\nrotational symmetry displays second-order topological superconductivity. Our\napproach is based on stacked Dirac Hamiltonians, using which we relate\ntransitions between topological phases to the transformation properties between\nadjacent gapped boundaries. We find that in addition to the bulk rotational\ninvariants, the presence of Majorana boundary bound states in a given geometry\ndepends on the interplay between weak topological invariants and the location\nof the rotation center relative to the lattice. We provide numerical examples\nfor our predictions and discuss possible extensions of our approach.",
        "positive": "Topological magnon-polaron transport in a bilayer van der Waals magnet: The stacking of intrinsically magnetic van der Waals materials provides a\nfertile platform to explore tunable transport effects of magnons, presenting\nsignificant prospects for spintronic applications. The possibility of having\ntopologically nontrivial magnons in these systems can further expand the scope\nof exploration. In this work, we consider a bilayer system with intralayer\nferromagnetic exchange and a weak interlayer antiferromagnetic exchange, and\nstudy the topological magnon-polaron excitations induced by magnetoelastic\ncouplings. Under an applied magnetic field, the system features a metamagnetic\ntransition, where the magnetic ground state changes from antiparallel layers to\nparallel. We show that the metamagnetic transition is accompanied by a\ntransition of the topological structure of the magnon polarons, which results\nin discernible changes in the topology induced transport effects. The\nmagnetic-field dependence of the thermal Hall conductivity and spin Nernst\ncoefficient is analyzed with linear response theories."
    },
    {
        "anchor": "Spectral properties of rotating electrons in quantum dots and their\n  relation to quantum Hall liquids: The exact diagonalization technique is used to study many-particle properties\nof interacting electrons with spin, confined in a two-dimensional harmonic\npotential. The single-particle basis is limited to the lowest Landau level. The\nresults are analyzed as a function of the total angular momentum of the system.\nOnly at angular momenta corresponding to the filling factors 1, 1/3, 1/5 etc.\nthe system is fully polarized. The lowest energy states exhibit spin-waves,\ndomains, and localization, depending on the angular momentum. Vortices exist\nonly at excited polarized states. The high angular momentum limit shows\nlocalization of electrons and separation of the charge and spin excitations.",
        "positive": "Spin conversion rates due to dipolar interactions in mono-isotopic\n  quantum dots at vanishing spin-orbit coupling: Dipolar interaction between the magnetic moments of electrons is studied as a\nsource for electron spin decay in quantum dots or arrays of quantum dots. This\nmagnetic interaction will govern spin decay, after other sources, such as the\ncoupling to nuclear spins or spin orbit coupling, have been eliminated by a\nsuitable sample design. Electron-electron (Coulomb) interactions, important for\nmagnetic properties, are included. Decomposing the dipolar operator according\nto the symmetric group of electron permutations allows one to deduce vanishing\ndecay channels as a function of electron number and spatial symmetries of the\nquantum dot(s). Moreover, we incorporate the possibility of rapid phonon\ninduced spin conserving transitions which crucially affect the temperature\ndependence of spin decay rates. An interesting result is that a sharp increase\nof the spin decay rate occurs already at relatively low temperatures."
    },
    {
        "anchor": "Observation of flat and weakly dispersing bands in a van der Waals\n  semiconductor Nb3Br8 with breathing kagome lattice: Niobium halides, Nb3X8 (X = Cl,Br,I), which are predicted two-dimensional\nmagnets, have recently gotten attention due to their breathing kagome geometry.\nHere, we have studied the electronic structure of Nb3Br8 by using\nangle-resolved photoemission spectroscopy (ARPES) and first-principles\ncalculations. ARPES results depict the presence of multiple flat and weakly\ndispersing bands. These bands are well explained by the theoretical\ncalculations, which show they have Nb d character indicating their origination\nfrom the Nb atoms forming the breathing kagome plane. This van der Waals\nmaterial can be easily thinned down via mechanical exfoliation to the ultrathin\nlimit and such ultrathin samples are stable as depicted from the time-dependent\nRaman spectroscopy measurements at room temperature. These results demonstrate\nthat Nb3Br8 is an excellent material not only for studying breathing kagome\ninduced flat band physics and its connection with magnetism, but also for\nheterostructure fabrication for application purposes.",
        "positive": "Perfect valley filter in strained graphene with single barrier region: We present a single barrier system to generate pure valley-polarized current\nin monolayer graphene. A uniaxial strain is applied within the barrier region,\nwhich is delineated by localized magnetic field created by ferromagnetic\nstripes at the regions boundaries. We show that under the condition of matching\nmagnetic field strength, strain potential, and Fermi energy, the transmitted\ncurrent is composed of only one valley contribution. The desired valley current\ncan transmit with zero reflection while the electrons from the other valley are\ntotally reflected. Thus, the system generates pure valley-polarized current\nwith maximum conductance. The chosen parameters of uniaxial strain and magnetic\nfield are in the range of experimental feasibility, which suggests that the\nproposed scheme can be realized with current technology."
    },
    {
        "anchor": "Detection of field-free magnetization switching through thermoelectric\n  effect in Ta/Pt/Co/Pt with significant spin-orbit torque and competing spin\n  currents: Application of sufficient lateral current to a heavy metal (HM) can switch\nthe perpendicular magnetization orientation of adjacent ferromagnetic layer\n(FM) through spin-orbit torques (SOTs). The choice of the HM and its\narrangement plays a major role for the SOT induced magnetization switching in\nmagnetic heterostructures. Here, in asymmetric Pt/Co/Pt heterostructures,\nanti-damping (AD) SOT prevails. Ta addition to this stack (Ta/Pt/Co/Pt) give\nrise to several compelling effects viz. competing spin currents (due to\nopposite spin-Hall angles of adjacent Ta and Pt layers), significant AD-SOT,\nthermoelectric effects (particularly, anomalous Nernst effect (ANE)), and\nenhanced perpendicular magnetic anisotropy. For this Ta/Pt/Co/Pt stack, the\nAD-SOT values are stabilized to that of the Pt/Co/Pt stack, which is\nsignificant than what is expected for a stack with competing spin currents.\nCurrent-induced field-free magnetization switching was absent in uniformly\ngrown Ta/Pt/Co/Pt stack. It was observed that a thickness gradient is essential\nto assist the field-free magnetization switching in these heterostructures.\nFurther, the thermoelectric effects are utilized to develop a technique to\ndetect the field-free magnetization switching. This technique detects the\nsecond harmonic ANE signal as a reading mechanism. Using ANE symmetry with the\napplied current, the switching can be detected in a single current sweep which\nwas corroborated to the conventional DC Hall method.",
        "positive": "Full counting statistics of strongly non-Ohmic transport through single\n  molecules: We study analytically the full counting statistics of charge transport\nthrough single molecules, strongly coupled to a weakly damped vibrational mode.\nThe specifics of transport in this regime - a hierarchical sequence of\navalanches of transferred charges, interrupted by \"quiet\" periods - make the\ncounting statistics strongly non-Gaussian. We support our findings for the\ncounting statistics as well as for the frequency-dependent noise power by\nnumerical simulations, finding excellent agreement."
    },
    {
        "anchor": "Development of a Scanning Tunneling Microscope for Variable Temperature\n  Electron Spin Resonance: Recent advances in increasing the spectroscopic energy resolution in scanning\ntunneling microscopy (STM) have been achieved by integrating electron spin\nresonance (ESR) with STM. Here, we demonstrate the design and performance of a\nhome-built STM capable of ESR at temperatures ranging from 1 K to 10 K. The STM\nis incorporated with a home-built Joule-Thomson refrigerator and a 2-axis\nvector magnet. Our STM design allows for the deposition of atoms and molecules\ndirectly into the cold STM, eliminating the need to extract the sample for\ndeposition. In addition, we adopt two methods to apply radio-frequency (RF)\nvoltages to the tunnel junction, the early design of wiring to the STM tip\ndirectly, and a more recent idea to use an RF antenna. Direct comparisons of\nESR results measured using the two methods and simulations of electric field\ndistribution around the tunnel junction show that, despite their different\ndesigns and capacitive couplings to the tunnel junction, there is no\ndiscernible difference in the driving and detection of ESR. Furthermore, at a\nmagnetic field of 1.6 T, we observe ESR signals (near 40 GHz) sustained up to\n10 K, which is the highest temperature for ESR-STM measurement reported to\ndate, to the best of our knowledge. Although the ESR intensity exponentially\ndecreases with increasing temperature, our ESR-STM system with low noise at the\ntunnel junction allows us to measure weak ESR signals with intensities in the\nsub-fA range. Our new design of ESR-STM, which is operational in a large\nfrequency and temperature range, can broaden the use of ESR spectroscopy in STM\nand enable the simple modification of existing STM systems, which will\nhopefully accelerate a generalized use of ESR-STM.",
        "positive": "Enhanced Zeeman splitting in Ga0.25In0.75As quantum point contacts: The strength of the Zeeman splitting induced by an applied magnetic field is\nan important factor for the realization of spin-resolved transport in\nmesoscopic devices. We measure the Zeeman splitting for a quantum point contact\netched into a Ga0.25In0.75As quantum well, with the field oriented parallel to\nthe transport direction. We observe an enhancement of the Lande g-factor from\n|g*|=3.8 +/- 0.2 for the third subband to |g*|=5.8 +/- 0.6 for the first\nsubband, six times larger than in GaAs. We report subband spacings in excess of\n10 meV, which facilitates quantum transport at higher temperatures."
    },
    {
        "anchor": "Band-pass superlattice magnetic tunnel junctions: Significant scientific and technological progress in the field of spintronics\nis based on trilayer magnetic tunnel junction devices which principally rely on\nthe physics of single barrier tunneling. While technologically relevant devices\nhave been prototyped, the physics of single barrier tunneling poses ultimate\nlimitations on the performance of magnetic tunnel junction devices. Here, we\npropose a fresh route toward high performance magnetic tunnel junctions by\nmaking electronic analogs of optical phenomena such as anti-reflections and\nFabry-P\\`erot resonances. The devices we propose feature anti-reflection\nenabled superlattice heterostructures sandwiched between the fixed and the free\nferromagnets of the magnetic tunnel junction structure. Our predictions are\nbased on the non-equilibrium Green's function spin transport formalism coupled\nself-consistently with the Landau-Lifshitz-Gilbert-Slonczewski equation. Owing\nto the physics of bandpass spin filtering in the bandpass superlattice magnetic\ntunnel junction device, we demonstrate an ultra-high boost in the tunnel\nmagneto-resistance (TMR$\\approx5\\times10^4\\%$) and nearly 92% suppression of\nspin transfer torque switching bias in comparison to a traditional trilayer\nmagnetic tunnel junction device. We rationalize improvised spin transfer torque\nswitching via analysis of the Slonczewski spin current transmission spectra.\nThe proof of concepts presented here can lead to next-generation spintronics\ndevice design harvesting the rich physics of superlattice heterostructures and\nexploiting spintronic analogs of optical phenomena.",
        "positive": "Flux noise in a superconducting transmission line: We study a superconducting transmission line (TL) formed by distributed LC\noscillators and excited by external magnetic fluxes which are aroused from\nrandom magnetization (A) placed in substrate or (B) distributed at interfaces\nof a two-wire TL. Low-frequency dynamics of a random magnetic field is\ndescribed based on the diffusion Langevin equation with a short-range source\ncaused by (a) random amplitude or (b) gradient of magnetization. For a TL\nmodeled as a two-port network with open and shorted ends, the effective\nmagnetic flux at the open end has non-local dependency on noise distribution\nalong the TL. The flux-flux correlation function is evaluated and analyzed for\nthe regimes (Aa), (Ab). (Ba), and (Bb). Essential frequency dispersion takes\nplace around the inverse diffusion time of random flux along the TL. Typically,\nnoise effect increases with size faster than the area of TL. The flux-flux\ncorrelator can be verified both via the population relaxation rate of the\nqubit, which is formed by the Josephson junction shunted by the TL with flux\nnoises, and via random voltage at the open end of the TL."
    },
    {
        "anchor": "Bayesian autotuning of Hubbard model quantum simulators: Spins in gated semiconductor quantum dots (QDs) are a promising platform for\nHubbard model simulation inaccessible to computation. Precise control of the\ntunnel couplings by tuning voltages on metallic gates is vital for a successful\nQD-based simulator. However, the number of tunable voltages and the complexity\nof the relationships between gate voltages and the parameters of the resulting\nHubbard models quickly increase with the number of quantum dots. As a\nconsequence, it is not known if and how a particular gate geometry yields a\ntarget Hubbard model. To solve this problem, we propose a hybrid\nmachine-learning approach using a combination of support vector machines (SVMs)\nand Bayesian optimization (BO) to identify combinations of voltages that\nrealize a desired Hubbard model. SVM constrains the space of voltages by\nrejecting voltage combinations producing potentials unsuitable for\ntight-binding (TB) approximation. The target voltage combinations are then\nidentified by BO in the constrained subdomain. For large QD arrays, we propose\na scalable efficient iterative procedure using our SVM-BO approach, which\noptimises voltage subsets and utilises a two-QD SVM model for large systems.\nOur results use experimental gate lithography images and accurate integrals\ncalculated with linear combinations of harmonic orbitals to train the machine\nlearning algorithms.",
        "positive": "Simulation Study of Ge p-type Nanowire Schottky Barrier MOSFETs: Ambipolar currents in Germanium p-type nanowire Schottky barrier MOSFETs were\ncalculated fully quantum-mechanically by using the multi-band k.p method and\nthe non-equilibrium Green's function approach. We investigated the performance\nof devices with 100, 110, and 111 channel orientations, respectively, by\nvarying the nanowire width, Schottky barrier height, and EOT. The 111 oriented\ndevices showed the best performance. In comparison to Si as a channel material,\nGe is more desirable because more current can be injected into the channel,\nresulting in steeper subthreshold slope and higher on-state current. Our\ncalculations predict that the Ge channel devices should have an EOT gain of\n0.2-0.5 nm over Si channel devices."
    },
    {
        "anchor": "Hydrodynamic effects in interacting Fermi electron jets: We theoretically study hydrodynamic phenomena originating from\nelectron-electron collisions in a two-dimensional Fermi system. We demonstrate\nthat an electron beam sweeping past an aperture creates a pumping effect,\nattracting carriers from this aperture. This pumping effect originates from the\nspecific electric potential distribution induced by the injected electrons. In\nthe regions nearby the main stream of injected electrons, a positive potential\nis induced by the injected electrons. Thus, the normally repulsive Coulomb\ninteraction leads to an attractive force in the Fermi system. This quantum\npumping mechanism in a Fermi system differs qualitatively from the Bernoulli\npumping effect in classical liquids. We also discuss possible experimental\nrealizations.",
        "positive": "Effect of Coulomb blockade on STM current through a granular film: The electron transport through an array of tunnel junctions consisting of an\n  STM tip and a granular film is studied both theoretically and experimentally.\nWhen the tunnel resistance between the tip and a granule on the surface is much\nlarger than those between granules, a bottleneck of the tunneling current is\ncreated in the array. It is shown that the period of the Coulomb staircase(CS)\nis given by the capacitance at the bottleneck.\n  Our STM experiments on Co-Al-O granular films show the CS with a single\nperiod at room temperature. This provides a new possibility for\nsingle-electron-spin-electronic devices at room temperature."
    },
    {
        "anchor": "Electromagnetic radiation by electrons in corrugated graphene: The electromagnetic radiation of electrons in the corrugated graphene in the\npresence of the transport electric current in the ballistic regime is studied.\nRadiation of the similar nature can be observed in undulator and wiggler. We\nconsidered here an impact of the ripples in the monolayer graphene on its\nelectromagnetic properties. The electromagnetic radiation was actually\ncalculated with a use of the standard electromagnetic theory. Two cases, of\nregular and random structures are analyzed. Nonlinear relation between the\nrandom height function h(x,y) and the gauge field is shown to create the\nradiation frequency distribution central peak. Few mechanisms of ripples\nformation in monolayer graphene were considered. The ripples are considered as\nan incommensurate superstructure in the two-dimensional crystal, appearing as a\nresult of forming of periodic solutions in the in-plane optical phonon\nsubsystem. Possible instability of the flexural subsystem is discussed as well.",
        "positive": "Universal Properties of Linear Magnetoresistance in Strongly Disordered\n  Semiconductors: Linear magnetoresistance occurs in semiconductors as a consequence of strong\nelectrical disorder and is characterized by nonsaturating magnetoresistance\nthat is proportional to the applied magnetic field. By investigating a\ndisordered MnAs-GaAs composite material, it is found that the magnitude of the\nlinear magnetoresistance (LMR) is numerically equal to the carrier mobility\nover a wide range and is independent of carrier density. This behavior is\ncomplementary to the Hall effect that is independent of the mobility and\ndependent on the carrier density. Moreover, the LMR appears to be insensitive\nto the details of the disorder and points to a universal explanation of\nclassical LMR that can be applied to other material systems."
    },
    {
        "anchor": "Environmental Coulomb blockade of topological superconductor-normal\n  metal junctions: We study charge transport of a topological superconductor connected to\ndifferent electromagnetic environments using a low-energy description where\nonly the Majorana bound states in the superconductor are included. Extending\nearlier findings who found a crossover between perfect Andreev reflection with\nconductance $2e^2/h$ to a regime with blocked transport when the resistance of\nthe environment is larger than $2e^2/h$, we consider Majorana bound states\ncoupled to metallic dots. in particular, we study two topological\nsuperconducting leads connected by a metallic quantum dot in both the weak\ntunneling and strong tunneling regimes. For weak tunneling, we project onto the\nmost relevant charge states. For strong tunneling, we start from the Andreev\nfixed point and integrate out charge fluctuations which gives an effective\nlow-energy model for the non-perturbative gate-voltage modulated cotunneling\ncurrent. In both regimes and in contrast to cotunneling with normal leads, the\nconductance is temperature independent because of the resonant Andreev\nreflections, which are included to all orders.",
        "positive": "Numerical simulations versus theoretical predictions for a non-Gaussian\n  noise induced escape problem in application to full counting statistics: A theoretical approach for characterising the influence of asymmetry of noise\ndistribution on the escape rate of a multi-stable system is presented. This was\ncarried out via the estimation of an action, which is defined as an exponential\nfactor in the escape rate, and discussed in the context of full counting\nstatistics paradigm. The approach takes into account all cumulants of the noise\ndistribution and demonstrates an excellent agreement with the results of\nnumerical simulations. An approximation of the third order cumulant was shown\nto have limitations on the range of dynamic stochastic system parameters. The\napplicability of the theoretical approaches developed so far is discussed for\nan adequate characterisation of the escape rate measured in experiments."
    },
    {
        "anchor": "Fluctuation relations without micro-reversibility for two-terminal\n  conductors: In linear transport, the fluctuation-dissipation theorem relates equilibrium\ncurrent correlations to the linear conductance coefficient. Theory and\nexperiment have shown that in small electrical conductors the non-linear\nI-V-characteristic of two-terminal conductor exhibits terms which are\nasymmetric in magnetic field and thus micro-reversibility is manifestly broken.\nWe discuss a non-equilibrium fluctuation dissipation theorem which is not based\non micro-reversibility. It connects the antisymmetric nonlinear conductance\nwith the third cumulant of equilibrium current fluctuations and a noise term\nthat is proportional to temperature, magnetic field and voltage.",
        "positive": "Optical conductivity and resistivity in a four-band model for ZrTe$_5$\n  from ab-initio calculations: ZrTe$_5$ is considered a potential candidate for either a Dirac semimetal or\na topological insulator in close proximity to a topological phase transition.\nRecent optical conductivity results motivated a two-band model with a conical\ndispersion in 2D, in contrast to density functional theory calculations. Here,\nwe reconcile the two by deriving a four-band model for ZrTe$_5$ using\n$\\textbf{k} \\cdot \\textbf{p}$ theory, and fitting its parameters to the\nab-initio band structure. The optical conductivity with an adjusted electronic\nstructure matches the key features of experimental data. The chemical potential\nvaries strongly with temperature, to the point that it may cross the gap\nentirely between zero and room temperature. The temperature-dependent\nresistivity displays a broad peak, and confirms theoretically the conclusions\nof recent experiments attributing the origin of the resistivity peak to the\nlarge shift of the chemical potential with temperature."
    },
    {
        "anchor": "Single-electron tunneling in the fractional quantum Hall effect regime: A recent mean-field approach to the fractional quantum Hall effect (QHE) is\nreviewed, with a special emphasis on the application to single-electron\ntunneling through a quantum dot in a high magnetic field. The theory is based\non the adiabatic principle of Greiter and Wilczek, which maps an incompressible\nstate in the integer QHE on the fractional QHE. The single-particle\ncontribution to the addition spectrum is analyzed, for a quantum dot with a\nparabolic confining potential. The spectrum is shown to be related to the\nFock-Darwin spectrum in the integer QHE, upon substitution of the electron\ncharge by the fractional quasiparticle charge. Implications for the periodicity\nof the Aharonov-Bohm oscillations in the conductance are discussed.",
        "positive": "Admittance of planar two-terminal quantum systems: We develop an approach to calculate the admittance of effectively\none-dimensional open quantum systems in random phase approximation. The\nstationary, unperturbed system is described within the Landauer-B\\\"uttiker\nformalism taking into account the Coulomb interaction in the Hartree\napproximation. The dynamic changes in the effective potential are calculated\nmicroscopically from the charge-charge correlation function resulting from the\nstationary scattering states. We provide explicit RPA-expressions for the\nquantum admittance. As a first example the case of a quantum capacitor is\nconsidered where we can derive a small-frequency expansion for the admittance\nwhich lends itself to an experimental testing of the theory. A comparison of\nthe low-frequency expansion with the complete RPA-expression shows that for a\nquantum capacitor a simple classical equivalent circuit with\nfrequency-independent elements does not describe satisfactorily the\nquantum-admittance with increasing the frequency."
    },
    {
        "anchor": "Ultrafast Nonequilibrium Dynamics in Two-dimensional Quantum Spin-Hall\n  Materials: We develop the theoretical framework of nonequilibrium ultrafast photonics in\nmonolayer quantum spin-Hall insulators supporting a multitude of topological\nstates. In these materials, ubiquitous strong light-matter interactions in the\nfemtosecond scale lead to non-adiabatic quantum dynamics, resulting in\ntopology-dependent nonlinear optoelectronic transport phenomena. We investigate\nthe mechanism driving topological Dirac fermions interacting with strong\nultrashort light pulses and uncover various experimentally accessible physical\nquantities that encode fingerprints of the quantum material's topological\nelectronic state from the high harmonic generated spectrum. Our work sets the\ntheoretical cornerstones to realize the full potential of time-resolved\nharmonic spectroscopy for identifying topological invariants in two-dimensional\nquantum spin-Hall solid state systems.",
        "positive": "Rydberg Magnetoexcitons in Cu$_2$O Quantum Wells: We present theoretical approach that allows for calculation of optical\nfunctions for Cu$_2$O Quantum Well (QW) with Rydberg excitons in an external\nmagnetic field of an arbitrary field strength. Both Faraday and Voigt\nconfigurations are considered, in the energetic region of p-excitons. We use\nthe real density matrix approach and an effective e-h potential, which enable\nto derive analytical expressions for the QW magneto-optical functions. For both\nconfigurations, all three field regimes: weak, intermediate, and high field,\nare considered and treated separately. With the help of the developed\napproximeted method we are able to estimate the limits between the field\nregimes. The obtained theoretical magneto-absorption spectra show a good\nagreement with available experimental data."
    },
    {
        "anchor": "Modulation of Hanle magnetoresistance in an ultrathin platinum film by\n  ionic gating: Hanle magnetoresistance (HMR) is a type of magnetoresistance where interplay\nof the spin Hall effect, Hanle-type spin precession, and spin-dependent\nscattering at the top/bottom surfaces in a heavy metal controls the effect. In\nthis study, we modulate HMR in ultrathin Pt by ionic gating, where the surface\nRashba field created by a strong electric field at the interface between the\nionic gate and Pt plays the dominant role in the modulation. This finding can\nfacilitate investigations of gate-tunable, spin-related effects and fabrication\nof spin devices.",
        "positive": "Quantum nondemolition measurements of a qubit: The concept of quantum nondemolition (QND) measurement is extended to\ncoherent oscillations in an individual two-state system. Such a measurement\nenables direct observation of intrinsic spectrum of these oscillations avoiding\nthe detector-induced dephasing that affects the standard (non-QND)\nmeasurements. The suggested scheme can be realized in Josephson-junction qubits\nwhich combine flux and charge dynamics."
    },
    {
        "anchor": "Self-powered programmable van der Waals photodetectors with nonvolatile\n  semi-floating gate: Tunable photovoltaic photodetectors are of significant relevance in the\nfields of programmable and neuromorphic optoelectronics. However, their\nwidespread adoption is hindered by intricate architectural design and energy\nconsumption challenges. This study employs a nonvolatile MoTe2/hBN/graphene\nsemi-floating photodetector to address these issues. Programed with pulsed gate\nvoltage, the MoTe2 channel can be reconfigured from an n+-n to a p-n\nhomojunction, and the photocurrent transition changes from negative to positive\nvalues. Scanning photocurrent mapping reveals that the negative and positive\nphotocurrents are attributed to Schottky junction and p-n homojunction,\nrespectively. In the p-n configuration, the device demonstrates self-driven,\nlinear, rapid response (~3 ms), and broadband sensitivity (from 405 to 1500 nm)\nfor photodetection, with typical performances of responsivity at ~0.5 A/W and\ndetectivity ~1.6*10^12 Jones under 635 nm illumination. These outstanding\nphotodetection capabilities emphasize the potential of the semi-floating\nphotodetector as a pioneering approach for advancing logical and nonvolatile\noptoelectronics.",
        "positive": "On the temperature dependence of ballistic Coulomb drag in nanowires: We have investigated within the theory of Fermi liquid dependence of Coulomb\ndrag current in a passive quantum wire on the applied voltage $V$ across an\nactive wire and on the temperature $T$ for any values of $eV/k_BT$. We assume\nthat the bottoms of the 1D minibands in both wires almost coincide with the\nFermi level. We come to conclusions that 1) within a certain temperature\ninterval the drag current can be a descending function of the temperature $T$;\n2) the experimentally observed temperature dependence $T^{-0.77}$ of the drag\ncurrent can be interpreted within the framework of Fermi liquid theory; 3) at\nrelatively high applied voltages the drag current as a function of the applied\nvoltage saturates; 4) the screening of the electron potential by metallic gate\nelectrodes can be of importance."
    },
    {
        "anchor": "Symmetry breaking for ratchet transport in presence of interactions and\n  magnetic field: We study the microwave induced ratchet transport of two-dimensional electrons\non an oriented semidisk Galton board. The magnetic field symmetries of ratchet\ntransport are analyzed in presence of electron-electron interactions. Our\nresults show that a magnetic field asymmetric ratchet current can appear due to\ntwo contributions, a Hall drift of the rectified current that depends only\nweakly on electron-electron interactions and a breaking of the time reversal\nsymmetry due to the combined effects of interactions and magnetic field. In the\nlatter case, the asymmetry between positive and negative magnetic fields\nvanishes in the weak interaction limit. We also discuss the recent experimental\nresults on ratchet transport in asymmetric nanostructures.",
        "positive": "Group-IV monochalcogenide monolayers: two-dimensional ferroelectrics\n  with weak intra-layer bonds and a phosphorene-like monolayer dissociation\n  energy: We performed density functional theory calculations with self-consistent van\nder Waals corrected exchange-correlation (XC) functionals to capture the\nstructure of black phosphorus and twelve monochalcogenide monolayers and find\nthe following results: (a) The in-plane unit cell changes its area in going\nfrom the bulk to a monolayer. The change of in-plane distances implies that\nbonds weaker than covalent or ionic ones are at work within the monolayers\nthemselves. This observation is relevant for the prediction of the critical\ntemperature $T_c$. (b) There is a hierarchy of independent parameters that\nuniquely define a ground state ferroelectric unit cell (and square and\nrectangular paraelectric unit cells as well): only 5 optimizable parameters are\nneeded to establish the unit cell vectors and the four basis vectors of the\nferroelectric ground state unit cell, while square and rectangular paraelectric\nstructures are defined by only 3 or 2 independent optimizable variables,\nrespectively. (c) The reduced number of independent structural variables\ncorrelates with larger elastic energy barriers on a rectangular paraelectric\nunit cell when compared to the elastic energy barrier of a square paraelectric\nstructure. This implies that $T_c$ obtained on a structure that keeps the\nlattice parameters fixed (for example, using an NVT ensemble) should be larger\nthan the transition temperature on a structure that is allowed to change\nin-plane lattice vectors (for example, using the NPT ensemble). (d) The\ndissociation energy (bulk cleavage energy) of these materials is similar to the\nenergy required to exfoliate graphite and MoS$_2$. (e) There exists a linear\nrelation among the square paraelectric unit cell lattice parameter and the\nlattice parameters of the rectangular ferroelectric ground state unit cell.\nThese results highlight the subtle atomistic structure of these novel 2D\nferroelectrics."
    },
    {
        "anchor": "Induced superconductivity in magic-angle twisted trilayer graphene\n  through graphene-metal contacts: Magic-angle twisted trilayer graphene (MATTG) recently exhibited robust\nsuperconductivity at a higher transition temperature (TC) than the bilayer\nversion. With electric gating from both the top and bottom sides, the\nsuperconductivity was found to be closely associated to two conditions: the\nfinite broken mirror symmetry and carrier concentrations between two to three\ncarriers per moir\\'e unite cell. Both conditions may be achieved by\ngraphene-metal contacts where charge transfers and interfacial electric fields\nare generated to balance work function mismatch. In this study, we explore the\nsuperconductivity of MATTG when contacting a metal, through self-consistently\nsolving the interfacial charge transfer with a highly electric-field-dependent\nband structure of MATTG. The predicted TC of MATTG-metal contacts forms two\ndomes as a function of the work function difference over the interface, with a\nmaximum over 2 K. Our work provides a constructive reference for graphene\nexperiments and industrial applications with graphene-metal and\ngraphene-semiconductor contacts.",
        "positive": "Control of the magnon-polariton hybridization with a microwave pump: Pump-induced magnon modes (PIMs) are recently discovered elementary\nexcitations in ferrimagnets that offer significant tunability to spin dynamics.\nHere, we investigate the coupling between a PIM and cavity magnon polaritons\n(CMPs) by driving a cavity magnonic system away from equilibrium with a\nmicrowave pump. In our experiment, the Walker mode simultaneously couples with\nthe PIM and cavity photons and thus combines two strongly coherent coupling\nprocesses in a single cavity structure. Such a PIM-CMP hybridization system\nacquires complementary properties from both the PIM and CMPs, allowing it to be\nfreely manipulated by the magnetic field, the pump power and the pump\nfrequency. These coherent manipulations exhibit unique behaviors beyond the\nintrinsic properties limited by the material nature and electromagnetic\nboundary conditions, thereby creating opportunities for extending the control\nof hybrid devices."
    },
    {
        "anchor": "Measurements of the spin relaxation rate at low magnetic fields in a\n  quantum dot: We measure the relaxation rate $W \\equiv T_{1}^{-1}$ of a single electron\nspin in a quantum dot at magnetic fields from 7 T down to 1.75 T, much lower\nthan previously measured. At 1.75 T we find that $T_{1}$ is 170 ms. We find\ngood agreement between our measurements and theoretical predictions of the\nrelaxation rate caused by the spin-orbit interaction, demonstrating that\nspin-orbit coupling can account for spin relaxation in quantum dots.",
        "positive": "Tuning the Fermi velocity in Dirac materials with an electric field: Dirac materials are characterized by energy-momentum relations that resemble\nthose of relativistic massless particles. Commonly denominated Dirac cones,\nthese dispersion relations are considered to be their essential feature. These\nmaterials comprise quite diverse examples, such as graphene and topological\ninsulators. Band-engineering techniques should aim to a full control of the\nparameter that characterizes the Dirac cones: the Fermi velocity. We propose a\ngeneral mechanism that enables the fine-tuning of the Fermi velocity in Dirac\nmaterials in a readily accessible way for experiments. By embedding the sample\nin a uniform electric field, the Fermi velocity is substantially modified. We\nfirst prove this result analytically, for the surface states of a topological\ninsulator/semiconductor interface, and postulate its universality to other\nDirac materials. Then we check its correctness in carbon-based Dirac materials,\nnamely graphene nanoribbons and nanotubes, thus showing the validity of our\nhypothesis in both continuum and tight-binding calculations and in different\nDirac systems."
    },
    {
        "anchor": "Interplay of filling fraction and coherence in symmetry broken graphene\n  p-n junction: The coherence of quantum Hall (QH) edges play the deciding factor in\ndemonstrating an electron interferometer, which has potential to realize a\ntopological qubit. A Graphene p-n junction (PNJ) with co-propagating spin and\nvalley polarized QH edges is a promising platform for studying an electron\ninterferometer. However, though a few experiments have been attempted for such\nPNJ via conductance measurements, the edge dynamics (coherent or incoherent) of\nQH edges at a PNJ, where either spin or valley symmetry or both are broken,\nremain unexplored. In this work, we have carried out the measurements of\nconductance together with shot noise, an ideal tool to unravel the dynamics, at\nlow temperature (~ 10mK) in a dual graphite gated hexagonal boron nitride (hBN)\nencapsulated high mobility graphene device. The conductance data show that the\nsymmetry broken QH edges at the PNJ follow spin selective equilibration. The\nshot noise results as a function of both p and n side filling factors reveal\nthe unique dependence of the scattering mechanism with filling factors.\nRemarkably, the scattering is found to be fully tunable from incoherent to\ncoherent regime with the increasing number of QH edges at the PNJ, shedding\ncrucial insights into graphene based electron interferometer.",
        "positive": "NMR linewidth and Skyrmion localization in quantum Hall ferromagnets: The non-monotonic behavior of the NMR signal linewidth in the 2D quantum Hall\nsystem is explained in terms of the interplay between skyrmions localization,\ndue to the influence of disorder, and the non-trivial temperature dependent\nskyrmion dynamics."
    },
    {
        "anchor": "Nonreciprocal phonon dichroism induced by Fermi pocket anisotropy in\n  two-dimensional Dirac materials: Electrons in two-dimensional (2D) Dirac materials carry local band geometric\nquantities, such as the Berry curvature and orbital magnetic moments, which,\ncombined with electron-phonon coupling, may affect the phonon dynamics in an\nunusual way. Here, we propose intrinsic nonreciprocal linear and circular\nphonon dichroism in magnetic 2D Dirac materials, which originate from nonlocal\nband geometric quantities of electrons and reduce to pure Fermi-surface\nproperties for acoustic phonons. We find that to acquire the nonreciprocity,\nthe Fermi pocket anisotropy rather than the chirality of electrons is crucial.\nTwo possible mechanisms of Fermi pocket anisotropy are suggested: (i) trigonal\nwarping and out-of-plane magnetization or (ii) Rashba spin-orbit interaction\nand in-plane magnetization. As a concrete example, we predict appreciable and\ntunable nonreciprocal phonon dichroism in 2H-MoTe 2 on a EuO substrate. Our\nfinding points to a different route towards electrical control of phonon\nnonreciprocity for acoustoelectronics applications based on 2D quantum\nmaterials.",
        "positive": "Fourier Transform Analysis of STM Images of Multilayer Graphene Moir\u00e9\n  Patterns: With the help of a simple model, we analyze Scanning Tunneling Microscopy\nimages of simple and double moir\\'e patterns resulting from misoriented bi- and\ntri-layers graphene stacks. It is found that the model reproduces surprisingly\nwell non-trivial features observed in the Fast Fourier Transform of the images.\nWe point out difficulties due to those features in interpreting the patterns\nseen on the FFT."
    },
    {
        "anchor": "Relaxation of the entanglement spectrum in quench dynamics of\n  topological systems: We study how the entanglement spectrum relaxes to its steady state in\none-dimensional quadratic systems after a quantum quench. In particular we\napply the saddle point expansion to the dimerized chains and 1-D p-wave\nsuperconductors. We find that the entanglement spectrum always exhibits a\npower-law relaxation superimposed with oscillations at certain characteristic\nangular frequencies. For the dimerized chains, we find that the exponent $\\nu$\nof the power-law decay is always $3/2$. For 1-D p-wave superconductors,\nhowever, we find that depending on the initial and final Hamiltonian, the\nexponent $\\nu$ can take value from a limited list of values. The smallest\npossible value is $\\nu=1/2$, which leads to a very slow convergence to its\nsteady state value.",
        "positive": "Reversible dynamics of single quantum emitters near metal-dielectric\n  interfaces: Here we present a systematic study of the dynamics of a single quantum\nemitter near a flat metal-dielectric interface. We identify the key elements\nthat determine the onset of reversibility in these systems by using a formalism\nsuited for absorbing media and through an exact integration of the dynamics.\nMoreover, when the quantum emitter separation from the surface is small, we are\nable to describe the dynamics within a pseudomode description that yields\nanalytical understanding and allows more powerful calculations."
    },
    {
        "anchor": "Effect of Coulomb interaction on chemical potential of metal film: The chemical potential of a metal film within the jellium model with taking\ninto account the Coulomb interaction between electrons is calculated. The\nsurface potential is modeled as the infinite rectangular potential well. The\nbehavior of the chemical potential as a function of the film thickness is\nstudied, the quantum size effect for this quantity is discovered. It is shown\nthat taking into account the Coulomb interaction leads to a significant\ndecrease of the chemical potential and to an enhancement of the quantum size\neffect.",
        "positive": "Thermally Activated Magnetization and Resistance Decay during Near\n  Ambient Temperature Aging of Co Nanoflakes in a Confining Semi-metallic\n  Environment: We report the observation of magnetic and resistive aging in a self assembled\nnanoparticle system produced in a multilayer Co/Sb sandwich. The aging decays\nare characterized by an initial slow decay followed by a more rapid decay in\nboth the magnetization and resistance. The decays are large accounting for\nalmost 70% of the magnetization and almost 40% of the resistance for samples\ndeposited at 35 $^oC$. For samples deposited at 50 $^oC$ the magnetization\ndecay accounts for $\\sim 50%$ of the magnetization and 50% of the resistance.\nDuring the more rapid part of the decay, the concavity of the slope of the\ndecay changes sign and this inflection point can be used to provide a\ncharacteristic time. The characteristic time is strongly and systematically\ntemperature dependent, ranging from $\\sim1$x$10^2 s$ at 400K to $\\sim3$x$10^5\ns$ at 320K in samples deposited at $35 ^oC$. Samples deposited at 50 $^oC$\ndisplayed a 7-8 fold increase in the characteristic time (compared to the $35\n^oC$ samples) for a given aging temperature, indicating that this timescale may\nbe tunable. Both the temperature scale and time scales are in potentially\nuseful regimes. Pre-Aging, Scanning Tunneling Microscopy (STM) reveals that the\nCo forms in nanoscale flakes. During aging the nanoflakes melt and migrate into\neach other in an anisotropic fashion forming elongated Co nanowires. This aging\nbehavior occurs within a confined environment of the enveloping Sb layers. The\nrelationship between the characteristic time and aging temperature fits an\nArrhenius law indicating activated dynamics."
    },
    {
        "anchor": "Full counting statistics of the photocurrent through a double quantum\n  dot embedded in a driven microwave resonator: Detection of single, itinerant microwave photons is an important\nfunctionality for emerging quantum technology applications as well as of\nfundamental interest in quantum thermodynamics experiments on heat transport.\nIn a recent experiment [W. Khan et al., Nat. Commun. 12, 5130 (2021)], it was\ndemonstrated that a double quantum dot (DQD) coupled to a microwave resonator\ncan act as an efficient and continuous photodetector by converting an incoming\nstream of photons to an electrical photocurrent. In the experiment, average\nphoton and electron flows were analyzed. Here we theoretically investigate, in\nthe same system, the fluctuations of the photocurrent through the DQD for a\ncoherent microwave drive of the resonator. We consider both the low frequency\nfull counting statistics as well as the finite-frequency noise (FFN) of the\nphotocurrent. Numerical results and analytical expressions in limiting cases\nare complemented by a mean-field approach neglecting dot-resonator\ncorrelations, providing a compelling and physically transparent picture of the\nphotocurrent statistics. We find that for ideal, unity efficiency detection,\nthe fluctuations of the charge current reproduce the Poisson statistics of the\nincoming photons, while the statistics for non-ideal detection is\nsub-Poissonian. Moreover, the FFN provides information of the system parameter\ndependence of detector short-time properties. Our results give novel insight\ninto microwave photon-electron interactions in hybrid dot-resonator systems and\nprovide guidance for further experiments on continuous detection of single\nmicrowave photons.",
        "positive": "Interatomic Coulombic Decay in two coupled Quantum Wells: Interatomic coulombic decay (ICD) is a relaxation process induced by\nelectronic correlation. In this work we study the ICD process in a two coupled\nQuantum wells (QWs) nano-structure. We study a simple one-dimensional effective\npotential using experimental parameters of the semiconductor QW layers i.e.\nusing the single band effective-mass approximation . In our calculations we\nconsider the discontinuity of the effective mass of the electron in each of the\nQW layers. We control the ICD lifetime by changing the distance between the two\nwells. The expected overall trend is a decrease of ICD lifetime with a decrease\nin the distance between the wells. We show that the distance can be tuned such\nthat the emitted ICD electron is trapped in a meta-stable state in the\ncontinuum i.e. a one electron resonance state. This causes the life time of the\nICD to be an order of magnitude smaller even in very long distances, and\nimproves the efficiency of the ICD. For the ICD to be dominant decay mechanism\nit must prevail over all other possible competitive decay processes. We have\nfound that the lifetime of the ICD is on the timescale of picoseconds.\nTherefore, based on our results we can design an experiment that will observe\nthe ICD phenomenon in QWs nano-structure for the first time. This work can lead\nto designing a wavelength sensitive detector which is efficient even in low\nintensities."
    },
    {
        "anchor": "Higher-Order Generalized Hydrodynamics of Carriers and Phonons in\n  Semiconductors in the Presence of Electric Fields: Macro to Nano: It is analyzed the hydrodynamics of carriers (charge and heat motion) and\nphonons (heat motion) in semiconductors in the presence of constant electric\nfields. This is done in terms of a so-called Higher-Order Generalized\nHydrodynamics (HOGH), also referred to as Mesoscopic Hydro-Thermodynamics\n(MHT), that is, covering phenomena involving motions displaying variations\nshort in space and fast in time and being arbitrarily removed from equilibrium,\nas it is the case in modern electronic devices. The particular case of a MHT of\norder 1 is described, covering wire samples from macro to nano sizes. Electric\nand thermal conductivities are obtained. As the size decreases towards the\nnanometric scale, the MHT of order 1 produces results that in some cases\ngreatly differ from those of the usual hydro-thermodynamics. The so-called\nMaxwell times associated to the different fluxes present in MHT are evidenced\nand analyzed; they have a quite relevant role in determining the\ncharacteristics of the motion.",
        "positive": "Fermi arc induced vortex structure in Weyl beam shifts: In periodic media, despite the close relationship between geometrical effects\nin the bulk and topological surface states, the two are typically probed\nseparately. We show that when beams in a Weyl medium reflect off an interface\nwith a gapped medium, the trajectory is influenced by both bulk geometrical\neffects and the Fermi arc surface states. The reflected beam experiences a\ndisplacement, analogous to the Goos-H\\\"anchen or Imbert-Fedorov shifts, that\nforms a half-vortex in the two-dimensional surface momentum space. The\nhalf-vortex is centered where the Fermi arc of the reflecting surface touches\nthe Weyl cone, with the magnitude of the shift scaling as an inverse square\nroot away from the touching-point, and diverging at the touching-point. This\nstriking feature provides a way to use bulk transport to probe the topological\ncharacteristics of a Weyl medium."
    },
    {
        "anchor": "Observation of the Metal-Insulator Transition in Two-Dimensional n-type\n  GaAs: The observation of a carrier-density driven metal-insulator transition in\nn-type GaAs-based heterostructure is reported. Although weaker than in\ncomparable-quality p-type GaAs samples, the main features of the transition are\nrather similar.",
        "positive": "Theory of Competing Charge Density Wave, Kekule and Antiferromagnetic\n  ordered Fractional Quantum Hall states in Graphene aligned with Boron Nitride: We investigate spin and valley symmetry-broken fractional quantum Hall phases\nwithin a formalism that naturally extends the paradigm of quantum Hall\nferromagnetism from integer to fractional quantum Hall states, allowing us to\nconstruct detailed phase diagrams for a large class of multi-component states.\nMotivated by recent experiments on Graphene aligned with a Boron Nitride\nsubstrate, we predict a sequence of transitions realized by increasing the\nmagnetic field, starting from a sub-lattice polarized state to a valley\ncoherent Kekule charge density wave state and further to an anti-ferromagnetic\nphase. Moreover for filling fractions such as $\\nu=\\pm 1/3$, we predict that\nthe system undergoes a transition at low fields, that not only differ by the\nspin-valley orientation of the fractionally filled flavors but also by their\nintrinsic fractional quantum Hall nature. This transition is from a\nLaughlin-like state to a two component Halperin-like state both with a charge\ndensity wave order. Moreover for $\\nu=\\pm 1/3,\\pm 2/3$, we predict a \"canted\nKekule density phase\"(CaKD) where the spinors of integer and fractionally\noccupied components have different orientations in the valley Bloch sphere, in\ncontrast to the Kekule state for the integer quantum Hall state at neutrality\nwhere both occupied components have the same orientation in the valley Bloch\nsphere."
    },
    {
        "anchor": "Edge and bulk merons in double quantum dots with spontaneous interlayer\n  phase coherence: We have investigated nucleation of merons in double quantum dots when a\nlateral distortion with a reflection symmetry is present in the confinement\npotential. We find that merons can nucleate both inside and at the edge of the\ndots. In addition to these merons, our results show that electron density\nmodulations can be also present inside the dots. An edge meron appears to have\napproximately a half integer winding number.",
        "positive": "Magnetoplasmon resonance in 2D electron system driven into a\n  zero-resistance state: We report on a remarkably strong, and a rather sharp, photoresistance peak\noriginating from a dimensional magnetoplasmon resonance (MPR) in a high\nmobility GaAs/AlGaAs quantum well driven by microwave radiation into a\nzero-resistance state (ZRS). The analysis of the MPR signalreveals a negative\nbackground providing experimental evidence for the concept of absolute negative\nresistance associated with the ZRS. When a system is further subject to a dc\nfield, the maxima of microwave-induced resistance oscillations decay away and a\nsystem reveals a state with close-to-zero differential resistance. The MPR\npeak, on the other hand, remains essentially unchanged, indicating surprisingly\nrobust Ohmic behavior under the MPR conditions."
    },
    {
        "anchor": "Kagome and honeycomb flat bands in moir\u00e9 graphene: We propose a class of graphene-based moir\\'e systems hosting flat bands on\nkagome and honeycomb moir\\'e superlattices. These systems are formed by\nstacking a graphene layer on a 2D substrate with lattice constant approximately\n$\\sqrt{3}$ times that of graphene. When the moir\\'e potentials are induced by a\n2D irreducible corepresentation in the substrate, the model shows a rich phase\ndiagram of low energy bands including eigenvalue fragile phases as well as\nkagome and honeycomb flat bands. Spin-orbit coupling in the substrate can lift\nsymmetry protected degeneracies and create spin Chern bands, and we observe\nspin Chern numbers up to three. We additionally propose a moir\\'e system formed\nby stacking two graphene-like layers with similar lattice constants and Fermi\nenergies but with Dirac Fermi velocities of opposite sign. This system exhibits\nmultiple kagome and honeycomb flat bands simultaneously. Both models we propose\nresemble the hypermagic model of [Scheer $\\textit{et al.}$, Phys. Rev. B\n$\\textbf{106}$, 115418 (2022)] and may provide ideal platforms for the\nrealization of strongly correlated topological phases.",
        "positive": "Molecular zero-range potential method and its application to cyclic\n  structures: The zero-range potentials of the radial Schrodinger equation are investigated\nfrom a point of Darboux transformations scheme. The dressing procedure is\nrealized as a sequence of Darboux transformations in a way similar to that used\nto obtain the generalized zero-range potentials of Huang-Derevianko by specific\nchoice of a family of parameters. In the present approach we stay within the\nframework of conventional zero-range potential method whilst the potential\nparameter (scattering length) is modified taken into account spectral molecular\nproperties. This allows to introduce molecular zero-range potential once the\ncorresponding discrete spectrum is known. The results are illustrated on\nexample of flat cyclic molecular structures, with particular focus on a benzene\nmolecule, which bounded states energies are first found using atomic zero-range\npotentials, compared with the Huckel method, and then used to introduce single\nzero-range potential describing the entire molecule. Reasonable scattering\nbehavior for newly introduced potential gives a possibility to tackle\nmany-molecule problems representing molecules as appropriate single zero-range\npotentials."
    },
    {
        "anchor": "Magneto-optical properties of topological insulator thin films with\n  broken inversion symmetry: We determine the optical response of ultrathin film topological insulators in\nthe presence of a quantizing external magnetic field taking into account both\nhybridization between surface states, broken inversion symmetry and explicit\ntime reversal symmetry breaking by the magnetic field. We find that breaking of\ninversion symmetry in the system, which can be due to interaction with a\nsubstrate or electrical gating, results in Landau level crossings which lead to\nadditional optical transition channels that were previously forbidden. We show\nthat by tuning the hybridization and symmetry breaking parameters, a transition\nfrom the normal to a topological insulator phase occurs with measurable\nsignatures in both the longitudinal and optical Hall conductivity.",
        "positive": "Spin dynamics and magneto-optical response in charge-neutral\n  tunnel-coupled quantum dots: We model the electron and hole spin dynamics in an undoped double quantum dot\nstructure, considering the carrier tunneling between quantum dots. Taking into\naccount also the presence of an in-plane or tilted magnetic field, we provide\nthe simulation of magneto-optical experiments, like the time resolved Kerr\nrotation measurement, which are performed currently on such structures to probe\nthe temporal spin dynamics. With our model, we reproduce the experimentally\nobserved effect of the extension of the spin polarization life time caused by\nthe spatial charge separation, which may occur in structures of this type.\nMoreover, we provide a number of qualitative predictions concerning the\nnecessary conditions for observation of this effect as well as about possible\nchannels of its suppression, including the spin-orbit coupling, which leads to\ntunneling of carriers accompanied by a spin-flip. We consider also the impact\nof the magnetic field tilting, which results in an interesting spin\npolarization dynamics."
    },
    {
        "anchor": "Effect of laser induced orbital momentum on magnetization switching: The observed magnetization switching by circularly polarized ultrafast laser\npulses has been attributed to the inverse Faraday effect in which the induced\nnon-equilibrium orbital momentum serves as an effective magnetic filed via\nspin-orbit coupling for magnetization rotation and switching. We critically\nexamine this scenario by explicitly calculating the magnitude of the induced\norbital momentum for generic itinerant band. We show that the calculated\ninduced angular momentum is not large enough for reversing the magnetization in\none laser pulse with the order of 100 femtosecond duration. Instead, we propose\nthat each laser pulse is capable to expand a reverse domain a few nano-meters\nand it takes multiple pulses to complete the magnetization reversal process via\ndomain wall motion.",
        "positive": "Extended excitons and compact helium-like biexcitons in type-II quantum\n  dots: We have used magneto-photoluminescence measurements to establish that\nInP/GaAs quantum dots have a type-II (staggered) band alignment. The average\nexcitonic Bohr radius and the binding energy are estimated to be 15nm and 1.5\nmeV respectively. When compared to bulk InP, the excitonic binding is weaker\ndue to the repulsive (type-II) potential at the hetero-interface. The\nmeasurements are extended to over almost six orders of magnitude of laser\nexcitation powers and to magnetic fields of up to 50 tesla. It is shown that\nthe excitation power can be used to tune the average hole occupancy of the\nquantum dots, and hence the strength of the electron-hole binding. The\ndiamagnetic shift coefficient is observed to drastically reduce as the quantum\ndot ensemble makes a gradual transition from a regime where the emission is\nfrom (hydrogen-like) two-particle excitonic states to a regime where the\nemission from (helium-like) four-particle biexcitonic states also become\nsignificant."
    },
    {
        "anchor": "Vortex Dynamics: Quantum versus Classical Regimes: For many years the classical Hall-Vinen-Iordanski (HVI) equation has been\nused to analyse vortex dynamics in superfluids. Here we discuss the extension\nof the theory of vortex dynamics to the quantum regime, in which the\ncharacteristic vortex frequency is higher than the temperature. At the same\ntime we justify, in the low-frequency classical regime, the use of the HVI\nequation, provided an inertial mass term and a noise fluctuation term are added\nto it. The crossover to the quantum regime is discussed, and an intuitive\npicture is given of the vortex dynamics, which in general is described by 2\nequations (one for the vortex coordinate, and one for its quantum\nfluctuations); we also discuss the simple equation of motion found in the\nextreme quantum regime.",
        "positive": "Transmutation of momentum into position in magnetic vortices: We show that transmutation of linear momentum into position may occur in a\nsystem of three magnetic vortices thanks to a direct link between topology and\ndynamics in a ferromagnet. This happens via exchange between the linear\nmomentum of a vortex-antivortex pair and the position of a single vortex during\na semi-elastic scattering process. Vortex polarity switching occurs in the case\nof inelastic collisions."
    },
    {
        "anchor": "S2DS: Physics-Based Compact Model for Circuit Simulation of\n  Two-Dimensional Semiconductor Devices Including Non-Idealities: We present a physics-based compact model for two-dimensional (2D)\nfield-effect transistors (FETs) based on monolayer semiconductors such as MoS2.\nA semi-classical transport approach is appropriate for the 2D channel, enabling\nsimplified analytical expressions for the drain current. In addition to\nintrinsic FET behavior, the model includes contact resistance, traps and\nimpurities, quantum capacitance, fringing fields, high-field velocity\nsaturation and self-heating, the latter being found to play a strong role. The\nmodel is calibrated with state-of-the-art experimental data for n- and p-type\n2D-FETs, and it can be used to analyze device properties for sub-100 nm gate\nlengths. Using the experimental fit, we demonstrate feasibility of circuit\nsimulations using properly scaled devices. The complete model is implemented in\nSPICE-compatible Verilog-A, and a downloadable version is freely available on\nthe nanoHUB.org.",
        "positive": "Extremely low inhomogeneous broadening of exciton lines in shallow\n  (In,Ga)As/GaAs quantum wells: We study radiative linewidth of exciton resonance in shallow\nIn$_x$Ga$_{1-x}$As/GaAs single quantum wells as a function of indium\nconcentration in the range $x=0.02...0.10$ and well thickness in the range\n$L_Z=1...30$ nm using the method of Brewster reflection spectroscopy. Record\nlinewidths of heavy-hole exciton resonance of about 130...180 $\\mu$eV are\nmeasured in reflection spectra for single quantum wells with $L_Z=2$ nm and\n$x=0.02$ at temperature 9 K. In these spectra, the non-radiative linewidth\nincluding inhomogeneous broadening can be comparable or even less than\nradiative linewidth. It is shown that radiative linewidth weakly depends on $x$\nand $L_Z$ in these ranges. In multiple-quantum-well Bragg structure with ten\nperiods radiative linewidth exceeds inhomogeneous broadening by 4 times."
    },
    {
        "anchor": "A Dual Gate Spin Field Effect Transistor With Very Low Switching Voltage\n  and Large ON-to-OFF Conductance Ratio: We propose and analyze a novel dual-gate Spin Field Effect Transistor\n(SpinFET) with half-metallic ferromagnetic source and drain contacts. The\ntransistor has two gate pads that can be biased independently. It can be\nswitched ON or OFF with a few mV change in the differential bias between the\ntwo pads, resulting in extremely low dynamic power dissipation during\nswitching. The ratio of ON to OFF conductance remains fairly large (~ 60) up to\na temperature of 10 K. This device also has excellent inverter characteristics,\nmaking it attractive for applications in low power and high density Boolean\nlogic circuits.",
        "positive": "Holomorphic quantum Hall states in higher Landau levels: Eigenstates of the planar magnetic Laplacian with homogeneous magnetic field\nform degenerate energy bands, the Landau levels. We discuss the unitary\ncorrespondence between states in higher Landau levels and those in the lowest\nLandau level, where wave functions are holomorphic. We apply this\ncorrespondence to many-body systems, in particular we represent effective\nHamiltonians and particle densities in higher Landau levels by corresponding\nquantities in the lowest Landau level."
    },
    {
        "anchor": "Entanglement Spectrum of a Disordered Topological Chern Insulator: How much information is stored in the ground-state of a system without\n\\emph{any symmetry} and how can we extract it? This question is investigated by\nanalyzing the behavior of a topological Chern Insulator (CI) in the presence of\ndisorder, with a focus on its entanglement spectrum (EtS) constructed from the\nground state. For systems with symmetries, the EtS was shown to contain\nexplicit information revealed by sorting the EtS against the conserved quantum\nnumbers. In the absence of any symmetry, we demonstrate that statistical\nmethods such as the level statistics of the EtS can be equally insightful,\nallowing us to distinguish when an insulator is in a topological or trivial\nphase and to map the boundary between the two phases, where EtS becomes\nentirely delocalized. The phase diagram of a CI is explicitly computed as\nfunction of Fermi level ($E_F$) and disorder strength using the level\nstatistics of the EtS and energy spectrum (EnS), together with a computation of\nthe Chern number via an efficient real-space formula.",
        "positive": "Producing nanodot arrays with improved hexagonal order by patterning\n  surfaces before ion sputtering: When the surface of a nominally flat binary material is bombarded with a\nbroad, normally-incident ion beam, disordered hexagonal arrays of nanodots can\nform. Shipman and Bradley have derived equations of motion that govern the\ncoupled dynamics of the height and composition of such a surface [P. D. Shipman\nand R. M. Bradley, Phys. Rev. B 84, 085420 (2011)]. We investigate the\ninfluence of initial conditions on the hexagonal order yielded by integration\nof those equations of motion. The initial conditions studied are hexagonal and\nsinusoidal templates, straight scratches and nominally flat surfaces. Our\nsimulations indicate that both kinds of template lead to marked improvements in\nthe hexagonal order if the initial wavelength is approximately equal to or\ndouble the linearly selected wavelength. Scratches enhance the hexagonal order\nin their vicinity if their width is close to or less than the linearly selected\nwavelength. Our results suggest that prepatterning a binary material can\ndramatically increase the hexagonal order achieved at large ion fluences."
    },
    {
        "anchor": "Gate-Tunable Transmon Using Selective-Area-Grown\n  Superconductor-Semiconductor Hybrid Structures on Silicon: We present a gate-voltage tunable transmon qubit (gatemon) based on planar\nInAs nanowires that are selectively grown on a high resistivity silicon\nsubstrate using III-V buffer layers. We show that low loss superconducting\nresonators with an internal quality of $2\\times 10^5$ can readily be realized\nusing these substrates after the removal of buffer layers. We demonstrate\ncoherent control and readout of a gatemon device with a relaxation time,\n$T_{1}\\approx 700\\,\\mathrm{ns}$, and dephasing times, $T_2^{\\ast}\\approx\n20\\,\\mathrm{ns}$ and $T_{\\mathrm{2,echo}} \\approx 1.3\\,\\mathrm{\\mu s}$.\nFurther, we infer a high junction transparency of $0.4 - 0.9$ from an analysis\nof the qubit anharmonicity.",
        "positive": "Mid-Infrared Ultrafast Carrier Dynamics in Thin Film Black Phosphorus: Black phosphorus is emerging as a promising semiconductor for electronic and\noptoelectronic applications. To study fundamental carrier properties, we\nperformed ultrafast femtosecond pump-probe spectroscopy on thin film black\nphosphorus mechanically exfoliated on a glass substrate. Carriers (electrons\nand holes) were excited to high energy levels and the process of carrier\nrelaxation through phonon emission and recombination was probed. We used a wide\nrange of probing wavelengths up to and across the band gap to study the\nevolution of the relaxation dynamics at different energy levels. Our\nexperiments revealed a plethora of important physical phenomena. The fast\nrelaxation time constants, associated with carrier-phonon scattering, steadily\nincrease as the energy of the probe beam approaches the band gap energy, which\nwas determined to be 0.31 eV, and the carrier recombination rate was obtained\nwhen the probe wavelength was tuned to match the band gap energy. The\ncarrier-phonon scattering rates were found to be similar along the armchair and\nzigzag directions, therefore, the anisotropic carrier mobility reported in\nliterature is mainly due to the difference in effective mass of carriers along\ndifferent directions. The ultrafast spectroscopy data further revealed the\noxidation induced surface charges. Our results highlight the importance of\nusing the spectroscopy technique, in this case, in the mid-IR range, to uncover\nuseful physical processes."
    },
    {
        "anchor": "Transport properties of individual C60-molecules: Electrical and thermal transport properties of C60 molecules are investigated\nwith density-functional-theory based calculations. These calculations suggest\nthat the optimum contact geometry for an electrode terminated with a single-Au\natom is through binding to one or two C-atoms of C60 with a tendency to promote\nthe sp2-hybridization into an sp3-type one. Transport in these junctions is\nprimarily through an unoccupied molecular orbital that is partly hybridized\nwith the Au, which results in splitting the degeneracy of the lowest unoccupied\nmolecular orbital triplet. The transmission through these junctions, however,\ncannot be modeled by a single Lorentzian resonance, as our results show\nevidence of quantum interference between an occupied and an unoccupied orbital.\nThe interference results in a suppression of conductance around the Fermi\nenergy. Our numerical findings are readily analyzed analytically within a\nsimple two-level model.",
        "positive": "Lateral manipulation with combined atomic force and scanning tunneling\n  microscopy using CO-terminated tips: CO-terminated tips currently provide the best spatial resolution obtainable\nin atomic force microscopy. Due to their chemical inertness, they allow to\nprobe interactions dominated by Pauli repulsion. The small size and inertness\nof the oxygen front atom yields unprecedented resolution of organic molecules,\nmetal clusters and surfaces. We study the capability of CO-terminated tips to\nlaterally manipulate single iron adatoms on the Cu(111) surface with combined\natomic force and scanning tunneling microscopy at 7\\,K. Furthermore, we find\nthat even a slight asymmetry of the tip results in a distortion of the lateral\nforce field. In addition, the influence of the tilt of the CO tip on the\nlateral force field is inverted compared to the use of a monoatomic metal tip\nwhich we can attribute to the inverted dipole moment of a CO tip with respect\nto a metal tip. Moreover, we demonstrate atom-by-atom assembly of iron clusters\nwith CO tips while using the high-resolution capability of the CO tips in\nbetween to determine the arrangement of the individual iron atoms within the\ncluster. Additionally, we were able to laterally manipulate single copper and\nsilicon adatoms without changing or losing the CO from the tip's apex."
    },
    {
        "anchor": "Chiral anomaly and longitudinal magnetotransport in type-II Weyl\n  semimetals: In the presence of parallel electric and magnetic fields, the violation of\nseparate number conservation laws for the three dimensional left and right\nhanded Weyl fermions is known as the chiral anomaly. The recent discovery of\nWeyl and Dirac semimetals has paved the way for experimentally testing the\neffects of chiral anomaly via longitudinal magneto-transport measurements. More\nrecently, a type-II Weyl semimetal (WSM) phase has been proposed, where the\nnodal points possess a finite density of states due to the touching between\nelectron- and hole- pockets. It has been suggested that the main difference\nbetween the two types of WSMs (type-I and type-II) is that in the latter,\nchiral anomaly and the associated longitudinal magneto-resistance are strongly\nanisotropic, vanishing when the applied magnetic field is perpendicular to the\ndirection of tilt of Weyl fermion cones in a type-II WSM. We analyze chiral\nanomaly in a type-II WSM in quasiclassical Boltzmann framework, and find that\nthe chiral anomaly induced positive longitudinal magneto-conductivity is\npresent along any arbitrary direction.",
        "positive": "Thermopower of a superconducting single-electron transistor: We present a linear-response theory for the thermopower of a single-electron\ntransistor consisting of a superconducting island weakly coupled to two\nnormal-conducting leads (NSN SET). The thermopower shows oscillations with the\nsame periodicity as the conductance and is rather sensitive to the size of the\nsuperconducting gap. In particular, the previously studied sawtooth-like shape\nof the thermopower for a normal-conducting single-electron device is\nqualitatively changed even for small gap energies."
    },
    {
        "anchor": "Hot-Carrier Separation in Heterostructure Nanowires observed by\n  Electron-Beam Induced Current: The separation of hot carriers in semiconductors is of interest for\napplications such as thermovoltaic photodetection and third-generation\nphotovoltaics. Semiconductor nanowires offer several potential advantages for\neffective hot-carrier separation such as: a high degree of control and\nflexibility in heterostructure-based band engineering, increased hot-carrier\ntemperatures compared to bulk, and a geometry well suited for local control of\nlight absorption. Indeed, InAs nanowires with a short InP energy barrier have\nbeen observed to produce electric power under global illumination, with an\nopen-circuit voltage exceeding the Shockley-Queisser limit. To understand this\nbehaviour in more detail, it is necessary to maintain control over the precise\nlocation of electron-hole pair-generation in the nanowire. In this work we\nperform electron-beam induced current measurements with high spatial\nresolution, and demonstrate the role of the InP barrier in extracting energetic\nelectrons. We interprete the results in terms of hot-carrier separation, and\nextract estimates of the hot carrier mean free path.",
        "positive": "Exciton spectrum in atomically thin monolayers: The role of hBN\n  encapsulation: The high-quality structures containing semiconducting transition metal\ndichalcogenides (S-TMDs) monolayer (MLs) required for optical and electrical\nstudies are achieved by their encapsulation in hexagonal BN (hBN) flakes. To\nexamine the effect of hBN thickness in these systems, we consider a model with\nan S-TMD ML placed between a semi-infinite in the out-of-plane direction\nsubstrate and complex top cover layers: a layer of finite thickness, adjacent\nto the ML, and a semi-infinite in the out-of-plane direction top part. We\nobtain the expression for the Coulomb potential for such a structure. Using\nthis result, we demonstrate that the energies of excitonic $s$ states in the\nstructure with WSe$_2$ ML change significantly for the top hBN with thickness\nless than 30 layers for different substrate cases, such as hBN and SiO$_2$. For\nthe larger thickness of the top hBN flake, the binding energies of the excitons\nare saturated to their values of the bulk hBN limit."
    },
    {
        "anchor": "Polariton Supercurrent Generation in Unipolar Electro-optic Devices: We describe a mechanism by which an electrical bias voltage applied across a\nunipolar semiconductor quantum well can drive an exciton or polariton\nsupercurrent. The mechanism depends on the properties of electronic\nquasiparticles in quantum wells or two-dimensional materials that are dressed\nby interactions with the coherent exciton field of an exciton condensate or the\ncoherent exciton and photon fields of a polariton condensate, and on\napproximate conservation laws. We propose experiments that can be performed to\nrealize this new light-matter coupling effect, and discuss possible\napplications.",
        "positive": "Quantum master equation scheme of time-dependent density functional\n  theory to time-dependent transport in nano-electronic devices: In this work a practical scheme is developed for the first-principles study\nof time-dependent quantum transport. The basic idea is to combine the transport\nmaster-equation with the well-known time-dependent density functional theory.\nThe key ingredients of this paper include: (i) the partitioning-free initial\ncondition and the consideration of the time-dependent bias voltages which base\nour treatment on the Runge-Gross existence theorem; (ii) the non-Markovian\nmaster equation for the reduced (many-body) central system (i.e. the device);\nand (iii) the construction of Kohn-Sham master equation for the reduced\nsingle-particle density matrix, where a number of auxiliary functions are\nintroduced and their equations of motion (EOM) are established based on the\ntechnique of spectral decomposition. As a result, starting with a well-defined\ninitial state, the time-dependent transport current can be calculated\nsimultaneously along the propagation of the Kohn-Sham master equation and the\nEOM of the auxiliary functions."
    },
    {
        "anchor": "Universal Scalings in 2D Anisotropic Dipolar Excitonic Systems: Low-dimensional excitonic materials have inspired much interest owing to\ntheir novel physical and technological prospects. In particular, those with\nstrong in-plane anisotropy are among the most intriguing but short of general\nanalyses. We establish the universal functional form of the anisotropic\ndispersion in the small $k$ limit for 2D dipolar excitonic systems. While the\nenergy is linearly dispersed in the direction parallel to the dipole in-plane,\nthe perpendicular direction is dispersionless up to linear order, which can be\nexplained by the quantum interference effect of the interaction among the\nconstituents of 1D subsystems. The anisotropic dispersion results in a\n$E^{\\sim0.5}$ scaling of the system density of states and predicts unique\nspectroscopic signatures including: (1) disorder-induced absorption linewidth,\n$W(\\sigma)\\sim\\sigma^{2.8}$, with $\\sigma$ the disorder strength, (2)\ntemperature dependent absorption linewidth, $W(T)\\sim T^{s+1.5}$, with $s$ the\nexponent of the environment spectral density, and (3) the out-of-plane angular\n$\\theta$ dependence of the peak splittings in absorption spectra, $\\Delta\nE(\\theta)\\propto\\sin^2\\theta$. These predictions are confirmed quantitatively\nwith numerical simulations of molecular thin films and tubules.",
        "positive": "Electron Transport Through the Two-Dimensional Atomic Lattice: The electrical conductivity changes of the Si(111)-(6x6)Au surface at early\nstage of Pb deposition was studied experimentally and theoretically as a\nfunction of coverage. Pb deposition onto a Si(111)-(6x6)Au surface induce\nstrong change of the conductance even at a low coverage ($<1$ monolayer). The\nexperimental results are analyzed using the theoretical model of two\ndimensional (2D) square atomic lattice."
    },
    {
        "anchor": "Intermolecular contrast in atomic force microscopy images without\n  intermolecular bonds: Intermolecular features in atomic force microscopy (AFM) images of organic\nmolecules have been ascribed to intermolecular bonds. A recent theoretical\nstudy [P. Hapala et al., Phys. Rev. B 90, 085421 (2014)] showed that these\nfeatures can also be explained by the flexibility of molecule terminated tips.\nWe probe this effect by carrying out AFM experiments on a model system that\ncontains regions where intermolecular bonds should and should not exist between\nclose-by molecules. Intermolecular features are observed in both regions,\ndemonstrating that intermolecular contrast cannot be directly interpreted as\nintermolecular bonds.",
        "positive": "Nanopatterning by Laser Interference Lithography: Applications to\n  Optical Devices: A systematic review, covering fabrication of nanoscale patterns by laser\ninterference lithography (LIL) and their applications for optical devices are\nprovided. LIL is a patterning method with simple, quick process over a large\narea without using a mask. LIL is a powerful technique for the definition of\nlarge-area, nanometer-scale, periodically patterned structures. Patterns are\nrecorded in a light-sensitive medium that responds nonlinearly to the intensity\ndistribution associated with the interference of two or more coherent beams of\nlight. The photoresist patterns produced with LIL are the platform for further\nfabrication of nanostructures and growth of functional materials which are the\nbuilding blocks for devices. Demonstration of optical and photonic devices by\nLIL is reviewed such as directed nano photonics and surface plasmon resonance\n(SPR) or large area membrane reflectors and anti-reflectors. Perspective on\nfuture directions for LIL and emerging applications in other fields are\npresented."
    },
    {
        "anchor": "Nontrivial transition of transmission in a highly open quantum point\n  contact in the quantum Hall regime: Transmission through a quantum point contact (QPC) in the quantum Hall regime\nusually exhibits multiple resonances as a function of gate voltage and high\nnonlinearity in bias. Such behavior is unpredictable and changes sample by\nsample. Here, we report the observation of a sharp transition of the\ntransmission through an open QPC at finite bias, which was observed\nconsistently for all the tested QPCs. It is found that the bias dependence of\nthe transition can be fitted to the Fermi-Dirac distribution function through\nuniversal scaling. The fitted temperature matches quite nicely to the electron\ntemperature measured via shot-noise thermometry. While the origin of the\ntransition is unclear, we propose a phenomenological model based on our\nexperimental results that may help to understand such a sharp transition.\nSimilar transitions are observed in the fractional quantum Hall regime, and it\nis found that the temperature of the system can be measured by rescaling the\nquasiparticle energy with the effective charge ($e^*=e/3$). We believe that the\nobserved phenomena can be exploited as a tool for measuring the electron\ntemperature of the system and for studying the quasiparticle charges of the\nfractional quantum Hall states.",
        "positive": "Misfit strain-induced energy dissipation for graphene/MoS2\n  heterostructure nanomechanical resonators: Misfit strain is inevitable in various heterostructures like the graphene/MoS\n2 van der Waals heterostructure. Although the misfit strain effect on\nelectronic and other physical properties have been well studied, it is still\nunclear how will the misfit strain affect the performance of the nanomechanical\nresonator based on the graphene/MoS 2 heterostructure. By performing molecular\ndynamics simulations, we disclose a misfit strain-induced decoupling phenomenon\nbetween the graphene layer and the MoS 2 layer during the resonant oscillation\nof the heterostructure. A direct relationship between the misfit strain and the\ndecoupling mechanism is successfully established through the retraction force\nanalysis. We further suggest to use the graphene/MoS 2 /graphene sandwich\nheterostructure for the nanomechanical resonator application, which is able to\nprevent the misfit strain-related decoupling phenomenon. These results provide\nvaluable information for the future application of the graphene/MoS 2\nheterostructure in the nanomechanical resonator field."
    },
    {
        "anchor": "Quadrupole Insulator without Corner States in the Energy Spectrum: The quadrupole insulator is a well-known instance of higher-order topological\ninsulators in two dimensions, which possesses midgap corner states in both the\nenergy spectrum and entanglement spectrum. Here, by constructing and exploring\na model Hamiltonian under a staggered $\\mathbb{Z}_2$ gauge field that respects\nmomentum-glide reflection symmetries, we surprisingly find a quadrupole\ninsulator that lacks zero-energy corner modes in its energy spectrum, despite\npossessing a nonzero quadrupole moment. Remarkably, the existence of midgap\ncorner modes is found in the entanglement spectrum. Since these midgap states\ncannot be continuously eliminated, the quadrupole insulator cannot be\ncontinuously transformed into a trivial topological insulator, thereby\nconfirming its topological nature. We show that the breakdown of the\ncorrespondence between the energy spectrum and entanglement spectrum occurs due\nto the closure of the edge energy gap when the Hamiltonian is flattened.\nFinally, we present a model that demonstrates an insulator with corner modes in\nthe energy spectrum even in the absence of the quadrupole moment. In this\nphase, the entanglement spectrum does not display any midgap states. The\nresults suggest that the bulk-edge correspondence of quadrupole insulators\ngenerally manifests in the entanglement spectrum rather than the energy\nspectrum.",
        "positive": "Degeneracy of the lowest Landau level and quantum group of the quantum\n  Hall effect on the Poincare half plane: The paper has been withdrawn by the author."
    },
    {
        "anchor": "Linear and Non-Linear Response of Quadratic Lindbladians: Quadratic Lindbladians encompass a rich class of dissipative electronic and\nbosonic quantum systems, which have been predicted to host new and exotic\nphysics. In this study, we develop a Lindblad-Keldysh spectroscopic response\nformalism for open quantum systems that elucidates their steady-state response\nproperties and dissipative phase transitions via finite-frequency linear and\nnon-linear probes. As illustrative examples, we utilize this formalism to\ncalculate the (1) density and dynamic spin susceptibilities of a boundary\ndriven XY model at and near criticality, (2) linear and non-linear optical\nresponses in Bernal bilayer graphene coupled to dissipative leads, and (3)\nsteady state susceptibilities in a bosonic optical lattice. We find that the XY\nmodel spin density wavelength diverges with critical exponent 1/2, and there\nare gapless dispersive modes in the dynamic spin response that originate from\nthe underlying spin density wave order; additionally the dispersing modes of\nthe weak and ultra-strong dissipation limits exhibit a striking correspondence\nsince the boundary dissipators couple only weakly to the bulk in both cases. In\nthe optical response of the Bernal bilayer, we find that the diamagnetic\nresponse can decrease with increasing occupation, as opposed to in closed\nsystems where the response increases monotonically with occupation; we study\nthe effect of second harmonic generation and shift current and find that these\nresponses, forbidden in centrosymmetric closed systems, can manifest in these\nopen systems as a result of dissipation. We compare this formalism to its\nequilibrium counterpart and draw analogies between these non-interacting open\nsystems and strongly interacting closed systems.",
        "positive": "Intermediate fixed point in a Luttinger liquid with elastic and\n  dissipative backscattering: In a recent work [Phys. Rev. Lett. {\\bf 108}, 136401 (2012)] we have\naddressed the problem of a Luttinger liquid with a scatterer that allows for\nboth coherent and incoherent scattering channels. We have found that the\nphysics associated with this model is qualitatively different from the elastic\nimpurity setup analyzed by Kane and Fisher, and from the inelastic scattering\nscenario studied by Furusaki and Matveev, thus proposing a new paradigmatic\npicture of Luttinger liquid with an impurity. Here we present an extensive\nstudy of the renormalization group flows for this problem, the fixed point\nlandscape, and scaling near those fixed points. Our analysis is\nnon-perturbative in the elastic tunneling amplitudes, employing an instanton\ncalculation in one or two of the available elastic tunneling channels. Our\nanalysis accounts for non-trivial Klein factors, which represent anyonic or\nfermionic statistics. These Klein factors need to be taken into account due to\nthe fact that higher order tunneling processes take place. In particular we\nfind a stable fixed point, where an incoming current is split ${1 \\over 2}$ -\n$1\\over 2$ between a forward and a backward scattered beams. This intermediate\nfixed point, between complete backscattering and full forward scattering, is\nstable for the Luttinger parameter $g<1$."
    },
    {
        "anchor": "Fast, low-current spin-orbit torque switching of magnetic tunnel\n  junctions through atomic modifications of the free layer interfaces: Future applications of spin-orbit torque will require new mechanisms to\nimprove the efficiency for switching nanoscale magnetic tunnel junctions\n(MTJs), while also controlling the magnetic dynamics to achieve fast,\nnanosecond scale performance with low write error rates. Here we demonstrate a\nstrategy to simultaneously enhance the interfacial magnetic anisotropy energy\nand suppress interfacial spin memory loss by introducing sub-atomic and\nmonatomic layers of Hf at the top and bottom interfaces of the ferromagnetic\nfree layer of an in-plane magnetized three-terminal MTJ device. When combined\nwith a beta-W spin Hall channel that generates spin-orbit torque, the\ncumulative effect is a switching current density of 5.4 x 106 A/cm2, more than\na factor of 3 lower than demonstrated in any other spin-orbit-torque magnetic\nmemory device at room temperature, and highly reliable switching with current\npulses only 2 ns long.",
        "positive": "Probing strain modulation in a gate-defined one dimensional electron\n  system: Gate patterning on semiconductors is routinely used to electrostatically\nrestrict electron movement into reduced dimensions. At cryogenic temperatures,\nwhere most studies are carried out, differential thermal contraction between\nthe patterned gate and the semiconductor often lead to an appreciable strain\nmodulation. The impact of such modulated strain to the conductive channel\nburied in a semiconductor has long been recognized, but measuring its magnitude\nand variation is rather challenging. Here we present a way to measure that\nmodulation in a gate-defined GaAs-based one-dimensional channel by applying\nresistively-detected NMR (RDNMR) with in-situ electrons coupled to quadrupole\nnuclei. The detected strain magnitude, deduced from the quadrupole-split\nresonance, varies spatially on the order of $10^{-4}$, which is consistent with\nthe predicted variation based on an elastic strain model. We estimate the\ninitial lateral strain $\\epsilon_{xx}$ developed at the interface to be about\n$3.5 \\times 10^{-3}$."
    },
    {
        "anchor": "Nanoscale Fabrication by Intrinsic Suppression of Proximity-Electron\n  Exposures and General Considerations for Easy & Effective Top-Down\n  Fabrication: We present results of a planar process development based on the combination\nof electron-beam lithography and dry etching for fabricating high-quality\nsuperconducting photosensitive structures in the sub-100nm regime. The devices\nwere fabricated by the application of an intrinsic proximity effect suppression\nprocedure which makes the need for an elaborated correction algorithm redundant\nfor planar design layouts which are orders of magnitude smaller than the\nbackscattering length. In addition, we discuss the necessary considerations for\nextending the fabrication spatial scale of optical contactlithography with a\nmercury arc-discharge photon source down to the order of the exposure photon's\nwavelength ( sub-{\\mu}m ), thereby minimizing the writing time on the\nelectron-beam lithograph. Finally we developed a unique and novel technique for\ncontrolling the undercut during a planar lift-off fabrication procedure without\ncleaving the wafer.",
        "positive": "Quantitative stray field imaging of a magnetic vortex core: Thin-film ferromagnetic disks present a vortex spin structure whose dynamics,\nadded to the small size (~10 nm) of their core, earned them intensive study.\nHere we use a scanning nitrogen-vacancy (NV) center microscope to\nquantitatively map the stray magnetic field above a 1 micron-diameter disk of\npermalloy, unambiguously revealing the vortex core. Analysis of both\nprobe-to-sample distance and tip motion effects through stroboscopic\nmeasurements, allows us to compare directly our quantitative images to\nmicromagnetic simulations of an ideal structure. Slight perturbations with\nrespect to the perfect vortex structure are clearly detected either due to an\napplied in-plane magnetic field or imperfections of the magnetic structures.\nThis work demonstrates the potential of scanning NV microscopy to map tiny\nstray field variations from nanostructures, providing a nanoscale,\nnon-perturbative detection of their magnetic texture."
    },
    {
        "anchor": "Oscillations of Induced Magnetization in Superconductor-Ferromagnet\n  Heterostructures: We study a change in the spin magnetization of a superconductor-ferromagnet\n(SF) heterostructure, when temperature is lowered below the superconducting\ntransition temperature. It is assumed that the SF interface is smooth on the\natomic scale and the mean free path is not too short. Solving the Eilenberger\nequation we show that the spin magnetic moment induced in the superconductor is\nan oscillating sign-changing function of the product $hd$ of the exchange field\n$h$ and the thickness $d$ of the ferromagnet. Therefore the total spin magnetic\nmoment of the system in the superconducting state can be not only smaller\n(screening) but also greater (anti-screening) than that in the normal state, in\ncontrast with the case of highly disordered (diffusive) systems, where only\nscreening is possible. This surprising effect is due to peculiar periodic\nproperties of localized Andreev states in the system. It is most pronounced in\nsystems with ideal ballistic transport (no bulk disorder in the samples, smooth\nideally transparent interface), however these ideal conditions are not crucial\nfor the very existence of the effect. We show that oscillations exist (although\nsuppressed) even for arbitrary low interface transparency and in the presence\nof bulk disorder, provided that $h \\tau \\gg 1$ ($\\tau$ -- mean free path). At\nlow interface transparency we solve the problem for arbitrary strength of\ndisorder and obtain oscillating magnetization in ballistic regime ($h \\tau \\gg\n1$) and nonoscillating magnetization in diffusive one ($h \\tau \\ll 1$) as\nlimiting cases of one formula.",
        "positive": "Size calibration of strained epitaxial islands due to dipole-monopole\n  interaction: Irreversible growth of strained epitaxial nanoislands has been studied with\nthe use of the kinetic Monte Carlo (KMC) technique. It has been shown that the\nstrain-inducing size misfit between the substrate and the overlayer produces\nlong range dipole-monopole (d-m) interaction between the mobile adatoms and the\nislands. To simplify the account of the long range interactions in the KMC\nsimulations, use has been made of a modified square island model. Analytic\nformula for the interaction between the point surface monopole and the dipole\nforces has been derived and used to obtain a simple expression for the\ninteraction between the mobile adatom and the rectangular island. The d-m\ninteraction was found to be longer ranged than the conventional dipole-dipole\npotential. The narrowing of the island size distributions (ISDs) observed in\nthe simulations was shown to be a consequence of a weaker repulsion of adatoms\nfrom small islands than from large ones which led to the preferential growth of\nthe former. Furthermore, similarly to the unstrained case, the power-law\nbehavior of the average island size and of the island density on the coverage\nhas been found. In contrast to the unstrained case, the value of the scaling\nexponent was not universal but strongly dependent on the strength of the long\nrange interactions. Qualitative agreement of the simulation results with some\npreviously unexplained behaviors of experimental ISDs in the growth of\nsemiconductor quantum dots was observed."
    },
    {
        "anchor": "Electron-Hole Binding Governs Carrier Transport in Halide Perovskite\n  Nanocrystal Thin Films: Two-dimensional halide perovskite nanoplatelets (NPLs) have exceptional\nlight-emitting properties, including wide spectral tunability, ultrafast\nradiative decays, high quantum yields (QY), and oriented emission. To realize\nefficient devices, it is imperative to understand how exciton transport\nprogresses in NPL thin films. Due to the high binding energies of electron-hole\npairs, excitons are generally considered the dominant species responsible for\ncarrier transfer. We employ spatially and temporally resolved optical\nmicroscopy to map exciton diffusion in perovskite nanocrystal (NC) thin films\nbetween 15 {\\deg}C and 50 {\\deg}C. At room temperature (RT), we find the\ndiffusion length to be inversely correlated to the thickness of the\nnanocrystals (NCs). With increasing temperatures, exciton diffusion declines\nfor all NC films, but at different rates. This leads to specific temperature\nturnover points, at which thinner NPLs exhibit higher diffusion lengths. We\nattribute this anomalous diffusion behavior to the coexistence of excitons and\nfree electron hole-pairs inside the individual NCs within our temperature\nrange. The organic ligand shell surrounding the NCs prevents charge transfer.\nAccordingly, any time an electron-hole pair spends in the unbound state reduces\nthe FRET-mediated inter-NC transfer rates and consequently the overall\ndiffusion. These results clarify how exciton diffusion progresses in strongly\nconfined halide perovskite NC films, emphasizing critical considerations for\noptoelectronic devices.",
        "positive": "Tuning Spin Dynamics and Localization Near the Metal-Insulator\n  Transition in Fe/GaAs heterostructures: We present a simultaneous investigation of coherent spin dynamics in both\nlocalized and itinerant carriers in Fe/GaAs heterostructures using ultrafast\nand spin-resolved pump-probe spectroscopy. We find that for excitation\ndensities that push the transient Fermi energy of photocarriers above the\nmobility edge there exist two distinct precession frequencies in the ob-served\nspin dynamics, allowing us to simultaneously monitor both localized and\nitinerant states. For low magnetic fields (below 3 T) the beat frequency\nbetween these two excitations evolves linearly, indicating that the nuclear\npolarization is saturated almost immediately and that the hyperfine coupling to\nthese two states is comparable, despite the 100x enhancement in nuclear\npolarization provided by the presence of the Fe layer. At higher magnetic\nfields (above 3 T) the Zeeman energy drives reentrant localization of the\nphotocarriers. Subtracting the constant hyperfine contribution from both sets\nof data allows us to extract the Lande g-factor for each state and estimate\ntheir energy relative to the bottom of the conduction band, yielding -2.16 meV\nand 17 meV for localized and itinerant states, respectively. This work advances\nour fundamental understanding of spin-spin interactions between electron and\nnuclear spin species, as well as between localized and itinerant electronics\nstates, and therefore has implications for future work in both spintronics and\nquantum information/computation."
    },
    {
        "anchor": "Electron density distribution and screening in rippled graphene sheets: Single-layer graphene sheets are typically characterized by long-wavelength\ncorrugations (ripples) which can be shown to be at the origin of rather strong\npotentials with both scalar and vector components. We present an extensive\nmicroscopic study, based on a self-consistent Kohn-Sham-Dirac\ndensity-functional method, of the carrier density distribution in the presence\nof these ripple-induced external fields. We find that spatial density\nfluctuations are essentially controlled by the scalar component, especially in\nnearly-neutral graphene sheets, and that in-plane atomic displacements are as\nimportant as out-of-plane ones. The latter fact is at the origin of a\ncomplicated spatial distribution of electron-hole puddles which has no evident\ncorrelation with the out-of-plane topographic corrugations. In the range of\nparameters we have explored, exchange and correlation contributions to the\nKohn-Sham potential seem to play a minor role.",
        "positive": "Non-invasive nanoscale potentiometry and ballistic transport in\n  epigraphene nanoribbons: The recent observation of non-classical electron transport regimes in\ntwo-dimensional materials has called for new high-resolution non-invasive\ntechniques to locally probe electronic properties. We introduce a novel hybrid\nscanning probe technique to map the local resistance and electrochemical\npotential with nm- and $\\mu$V resolution, and we apply it to study epigraphene\nnanoribbons grown on the sidewalls of SiC substrate steps. Remarkably, the\npotential drop is non uniform along the ribbons, and $\\mu$m-long segments show\nno potential variation with distance. The potential maps are in excellent\nagreement with measurements of the local resistance. This reveals ballistic\ntransport in ambient condition, compatible with micrometer-long\nroom-temperature electronic mean free paths."
    },
    {
        "anchor": "Microwave manipulation of electrically injected spin polarized electrons\n  in silicon: We demonstrate microwave manipulation of the spin states of electrically\ninjected spin-polarized electrons in silicon. Although the silicon channel is\nbounded by ferromagnetic metal films, we show that moderate microwave power can\nbe applied to the devices without altering the device operation significantly.\nResonant microwave irradiation is used to induce spin rotation of\nspin-polarized electrons as they travel across a silicon channel, and the\nresultant spin polarization is subsequently detected by a ferromagnetic\nSchottky barrier spin detector. These results demonstrate the potential for\ncombining advanced electron spin resonance techniques to complement the study\nof semiconductor spintronic devices beyond standard magnetotransport\nmeasurements.",
        "positive": "Long-term drift of Si-MOS quantum dots with intentional donor implants: Charge noise can be detrimental to the operation of quantum dot (QD) based\nsemiconductor qubits. We study the low-frequency charge noise by charge offset\ndrift measurements for Si-MOS devices with intentionally implanted donors near\nthe QDs. We show that the MOS system exhibits non-equilibrium drift\ncharacteristics in the form of transients and discrete jumps that are not\ndependent on the properties of the donor implants. The equilibrium charge noise\nindicates a $1/f$ noise dependence, and a noise strength as low as\n$1~\\mathrm{\\mu eV/\\sqrt{Hz}}$, comparable to that reported in more model GaAs\nand Si/SiGe systems (which have also not been implanted). We demonstrate that\nimplanted qubits, therefore, can be fabricated without detrimental effects on\nlong-term drift or $1/f$ noise."
    },
    {
        "anchor": "Studies of the Temperature-Driven Flow Lines and Phase Transitions in a\n  Two-Dimensional Si/SiGe Hole System: We have performed low-temperature transport experiments on a Si/SiGe hole\nsystem. The measured transverse and longitudinal condductivities $\\sigma_{xx}$\nand $\\sigma_{xy}$ allow us to study the magnetic-field-induced transitions in\nthe system. In particular, we present the first study of the temperature-driven\nflow lines in the \"anomalous Hall insulator\" regime near a Landau level filling\nfactor $\\nu=1.5$. The \"anomalous\" temperature-driven flow lines could be due to\nthe unusual energy level scheme in a Si/SiGe hole system. Moreover, for\n$3<\\nu<5$, there is a temperature-independent point in $\\rho_{xx} (B)$,\n$\\rho_{xy} (B)$, $\\sigma_{xx}$, and $\\sigma_{xy}$ which corresponds to a\nboundary of the quantum phase transition.",
        "positive": "A Quantum Approach of Meso-Magnet Dynamics with Spin Transfer Torque: We present a theory of magnetization dynamics driven by spin-polarized\ncurrent in terms of the quantum master equation. In the spin coherent state\nrepresentation, the master equation becomes a Fokker-Planck equation, which\nnaturally includes the spin transfer and quantum fluctuation. The current\nelectron scattering state is correlated to the magnet quantum states, giving\nrise to quantum correction to the electron transport properties in the usual\nsemiclassical theory. In the large spin limit, the magnetization dynamics is\nshown to obey the Hamilton-Jacobi equation or the Hamiltonian canonical\nequations."
    },
    {
        "anchor": "Higher-order topological insulators and superconductors protected by\n  inversion symmetry: We study surface states of topological crystalline insulators and\nsuperconductors protected by inversion symmetry. These fall into the category\nof \"higher-order\" topological insulators and superconductors which possess\nsurface states that propagate along one-dimensional curves (hinges) or are\nlocalized at some points (corners) on the surface. We show that the surface\nstates of higher-order topological insulators and superconductors can be\nthought of as globally irremovable topological defects and provide a complete\nclassification of these inversion-protected phases in any spatial dimension for\nthe ten symmetry classes by means of a layer construction. Furthermore, we\ndiscuss possible physical realizations of such states starting with a\ntime-reversal invariant topological insulator (class AII) in three dimensions\nor a time-reversal invariant topological superconductor (class DIII) in two or\nthree dimensions. The former can be used to build a three-dimensional\nsecond-order topological insulator which exhibits one-dimensional chiral or\nhelical modes propagating along opposite edges, whereas the latter enables the\nconstruction of three-dimensional third-order or two-dimensional second-order\ntopological superconductors hosting Majorana zero modes localized to two\nopposite corners. Being protected by inversion, such states are not pinned to a\nspecific pair of edges or corners thus offering the possibility of controlling\ntheir location by applying inversion-symmetric perturbations such as magnetic\nfield.",
        "positive": "Weak coupling approximations in non-Markovian Transport: We study the transport properties of the Fano-Anderson model with a\nLorentzian-shaped density of states in one of the electronic reservoirs. We\nexplicitly show that the energy dependence of the density of states can cause\nnon-Markovian effects and that the non-Markovian master equation may fail if\nthese effects are strong. We evaluate the stationary current, the zero\nfrequency current noise and the occupation dynamics of the resonant level by\nmeans of a quantum master equation approach within different approximation\nschemes and compare the results to the exact solution obtained by scattering\ntheory and Green's functions."
    },
    {
        "anchor": "All-optical control of the spontaneous emission of quantum dots using\n  coupled-cavity quantum electrodynamics: We demonstrate the remote all-optical control of the spontaneous emission\n(SE) of quantum dots using coupled photonic crystal cavities. By spectrally\ntuning a Fabry-Perot cavity in resonance with a target cavity, the quality\nfactor and the local density of states experienced by emitters in the target\ncavity are modified, leading to a change in the SE rate. From the theoretical\nanalysis of the coupled-cavity quantum electrodynamics system, the SE rate\nchange can be higher than the quality factor change due to a reduction of the\nvacuum field at the emitter's position when the two cavities are brought in\nresonance. Both the weak and strong coupling regimes of two cavities have been\nobserved experimentally and the SE decay rate has been modified by more than a\nfactor of three with remote optical control.",
        "positive": "Drift velocity of edge magnetoplasmons due to magnetic edge channels: Edge magnetoplasmons arise on a boundary of conducting layer in perpendicular\nmagnetic field due to an interplay of electron cyclotron motion and Coulomb\nrepulsion. Lateral electric field, which confines electrons inside the sample,\ndrives their spiraling motion in magnetic field along the edge with the average\ndrift velocity contributing to the total magnetoplasmon velocity. We revisit\nthis classical picture by developing fully quantum theory of drift velocity\nstarting from analysis of magnetic edge channels and their electrodynamic\nresponse. We derive the quantum-mechanical expression for the drift velocity,\nwhich arises in our theory as a characteristic of such response. Using the\nWiener-Hopf method to solve analytically the edge mode electrodynamic problem,\nwe demonstrate that the edge channel response effectively enhances the bulk\nHall response of the conducting layer and thus increases the edge\nmagnetoplasmon velocity. In the quasiclassical long-wavelength limit of our\nmodel, the drift velocity is simply added to the total magnetoplasmon velocity,\nin agreement with the classical picture."
    },
    {
        "anchor": "Weak-link Josephson Junctions Made from Topological Crystalline\n  Insulators: We report on the fabrication of Josephson junctions using the topological\ncrystalline insulator Pb$_{0.5}$Sn$_{0.5}$Te as the weak link. The properties\nof these junctions are characterized and compared to those fabricated with weak\nlinks of PbTe, a similar material yet topologically trivial. Most striking is\nthe difference in the AC Josephson effect: junctions made with\nPb$_{0.5}$Sn$_{0.5}$Te exhibit rich subharmonic structure consistent with a\nskewed current-phase relation. This structure is absent in junctions fabricated\nfrom PbTe. A discussion is given on the origin of this effect as an indication\nof novel behavior arising from the topologically nontrivial surface state.",
        "positive": "A Nonlinear Charge- and Flux-Tunable Cavity Derived from an Embedded\n  Cooper Pair Transistor: We introduce the cavity-embedded Cooper pair transistor (cCPT), a device\nwhich behaves as a highly nonlinear microwave cavity whose resonant frequency\ncan be tuned both by charging a gate capacitor and by threading flux through a\nSQUID loop. We characterize this device and find excellent agreement between\ntheory and experiment. A key difficulty in this characterization is the\npresence of frequency fluctuations comparable in scale to the cavity linewidth,\nwhich deform our measured resonance circles in accordance with recent\ntheoretical predictions [Brock et al., Phys. Rev. Applied 14, 054026 (2020)].\nBy measuring the power spectral density of these frequency fluctuations at\ncarefully chosen points in parameter space, we find that they are primarily a\nresult of the $1/f$ charge and flux noise common in solid state devices.\nNotably, we also observe key signatures of frequency fluctuations induced by\nquantum fluctuations in the cavity field via the Kerr nonlinearity."
    },
    {
        "anchor": "Magnetoplasmon excitations in arrays of circular and noncircular quantum\n  dots: We have investigated the magnetoplasmon excitations in arrays of circular and\nnoncircular quantum dots within the Thomas-Fermi-Dirac-von Weizs\\\"acker\napproximation. Deviations from the ideal collective excitations of isolated\nparabolically confined electrons arise from local perturbations of the\nconfining potential as well as interdot Coulomb interactions. The latter are\nunimportant unless the interdot separations are of the order of the size of the\ndots. Local perturbations such as radial anharmonicity and noncircular symmetry\nlead to clear signatures of the violation of the generalized Kohn theorem. In\nparticular, the reduction of the local symmetry from SO(2) to $C_4$ results in\na resonant coupling of different modes and an observable anticrossing behaviour\nin the power absorption spectrum. Our results are in good agreement with recent\nfar-infrared (FIR) transmission experiments.",
        "positive": "Interplay between interference and Coulomb interaction in the\n  ferromagnetic Anderson model with applied magnetic field: We study the competition between interference due to multiple single-particle\npaths and Coulomb interaction in a simple model of an Anderson-like impurity\nwith local-magnetic-field-induced level splitting coupled to ferromagnetic\nleads. The model along with its potential experimental relevance in the field\nof spintronics serves as a nontrivial benchmark system where various quantum\ntransport approaches can be tested and compared. We present results for the\nlinear conductance obtained by a spin-dependent implementation of the density\nmatrix renormalization group scheme which are compared with a mean-field\nsolution as well as a seemingly more advanced Hubbard-I approximation. We\nexplain why mean-field yields nearly perfect results, while the more\nsophisticated Hubbard-I approach fails, even at a purely conceptual level since\nit breaks hermiticity of the related density matrix. Furthermore, we study\nfinite bias transport through the impurity by the mean-field approach and\nrecently developed higher-order density matrix equations. We find that the\nmean-field solution fails to describe the plausible results of the higher-order\ndensity matrix approach both quantitatively and qualitatively as it does not\ncapture some essential features of the current-voltage characteristics such as\nnegative differential conductance."
    },
    {
        "anchor": "On Landauer--B\u00fcttiker formalism from a quantum quench: We study transport in the free fermionic one-dimensional systems subjected to\narbitrary local potentials. The bias needed for the transport is modeled by the\ninitial highly non-equilibrium distribution where only half of the system is\npopulated. Additionally to that, the local potential is also suddenly changed\nwhen the transport starts. For such a quench protocol we compute the Full\nCounting Statistics (FCS) of the number of particles in the initially empty\npart. In the thermodynamic limit, the FCS can be expressed via the Fredholm\ndeterminant with the kernel depending on the scattering data and Jost solutions\nof the pre-quench and the post-quench potentials. We discuss the large-time\nasymptotic behavior of the obtained determinant and observe that if two or more\nbound states are present in the spectrum of the post-quench potential the\ninformation about the initial state manifests itself in the persistent\noscillations of the FCS. On the contrary, when there are no bound states the\nasymptotic behavior of the FCS is determined solely by the scattering data of\nthe post-quench potential, which for the current (the first moment) is given by\nthe Landauer--B\\\"uttiker formalism. The information about the initial state can\nbe observed only in the transient dynamics.",
        "positive": "Single-charge detection by an atomic precision tunnel junction: We demonstrate sensitive detection of single charges using a planar tunnel\njunction 8.5nm wide and 17.2nm long defined by an atomically precise phosphorus\ndoping profile in silicon. The conductance of the junction responds to a nearby\ngate potential and also to changes in the charge state of a quantum dot\npatterned 52nm away. The response of this detector is monotonic across the\nentire working voltage range of the device, which will make it particularly\nuseful for studying systems of multiple quantum dots. The charge sensitivity is\nmaximized when the junction is most conductive, suggesting that more sensitive\ndetection can be achieved by shortening the length of the junction to increase\nits conductance."
    },
    {
        "anchor": "Interfacial Phonon Scattering and Transmission Loss in >1 um Thick\n  Silicon-on-insulator Thin Films: Scattering of phonons at boundaries of a crystal (grains, surfaces, or\nsolid/solid interfaces) is characterized by the phonon wavelength, the angle of\nincidence, and the interface roughness, as historically evaluated using a\nspecularity parameter p formulated by Ziman [J. M. Ziman, Electrons and Phonons\n(Clarendon Press, Oxford, 1960)]. This parameter was initially defined to\ndetermine the probability of a phonon specularly reflecting or diffusely\nscattering from the rough surface of a material. The validity of Ziman's theory\nas extended to solid/solid interfaces has not been previously validated. To\nbetter understand the interfacial scattering of phonons and to test the\nvalidity of Ziman's theory, we precisely measured the in-plane thermal\nconductivity of a series of Si films in silicon-on-insulator (SOI) wafers by\ntime-domain thermoreflectance (TDTR) for a Si film thickness range of 1 - 10\n{\\mu}m and a temperature range of 100 - 300 K. The Si/SiO2 interface roughness\nwas determined to be 0.11+/-0.04 nm using transmission electron microscopy\n(TEM). Furthermore, we compared our in-plane thermal conductivity measurements\nto theoretical calculations that combine first-principles phonon transport with\nZiman's theory. Calculations using Ziman's specularity parameter significantly\noverestimate values from the TDTR measurements. We attribute this discrepancy\nto phonon transmission through the solid/solid interface into the substrate,\nwhich is not accounted for by Ziman's theory for surfaces. We derive a simple\nexpression for the specularity parameter at solid/amorphous interfaces and\nachieve good agreement between calculations and measurement values.",
        "positive": "Spin polarization and g-factor enhancement in graphene nanoribbons in\n  magnetic field: We provide a systematic quantitative description of spin polarization in\narmchair and zigzag graphene nanoribbons in a perpendicular magnetic field. We\nfirst address spinless electrons within the Hartree approximation studying the\nevolution of the magnetoband structure and formation of the compressible\nstrips. We discuss the potential profile and the density distribution near the\nedges and the difference and similarities between armchair and zigzag edges.\nAccounting for the Zeeman interaction and describing the spin effects via the\nHubbard term we study the spin-resolved subband structure and relate the spin\npolarization of the system at hand to the formation of the compressible strips\nfor the case of spinless electrons. At high magnetic field the calculated\neffective g-factor varies around a value of <g*>~2.25 for armchair nanoribbons\nand <g*>~3 for zigzag nanoribbons. An important finding is that in zigzag\nnanoribbons the zero-energy mode remains pinned to the Fermi-energy and becomes\nfully spin-polarized for all magnetic fields, which, in turn, leads to a strong\nspin polarization of the electron density near the zigzag edge."
    },
    {
        "anchor": "Efficient C-Phase gate for single-spin qubits in quantum dots: Two-qubit interactions are at the heart of quantum information processing.\nFor single-spin qubits in semiconductor quantum dots, the exchange gate has\nalways been considered the natural two-qubit gate. The recent integration of\nmagnetic field or g-factor gradients in coupled quantum dot systems allows for\na one-step, robust realization of the controlled phase (C-Phase) gate instead.\nWe analyze the C-Phase gate durations and fidelities that can be obtained under\nrealistic conditions, including the effects of charge and nuclear field\nfluctuations, and find gate error probabilities of below 10-4, possibly\nallowing fault-tolerant quantum computation.",
        "positive": "Vacuum Annealed Cu contacts for graphene electronics: We present transfer-length-method measurements of the contact resistance\nbetween Cu and graphene, and a method to significantly reduce the contact\nresistance by vacuum annealing. Even in samples with heavily contaminated\ncontacts, the contacts display very low contact resistance post annealing. Due\nto the common use of Cu, and it's low chemical reactivity with graphene,\nthermal annealing will be important for future graphene devices requiring\nnon-perturbing contacts with low contact resistance."
    },
    {
        "anchor": "Emergent Weyl nodes and Fermi arcs in a Floquet Weyl semimetal: When a Dirac semimetal is subject to a circularly polarized laser, it is\npredicted that the Dirac cone splits into two Weyl nodes and a nonequilibrium\ntransient state called the Floquet Weyl semimetal is realized. We focus on the\npreviously unexplored low-frequency regime, where the upper and lower Dirac\nbands resonantly couple with each other through multi-photon processes, which\nis a realistic situation in solid state ultrafast pump-probe experiments. We\nfind a series of new Weyl nodes emerging in pairs when the Floquet replica\nbands hybridize with each other. The nature of the Floquet Weyl semimetal with\nregard to the number, locations, and monopole charges of these Weyl nodes is\nhighly tunable with the amplitude and frequency of the light. We derive an\neffective low energy theory using Brillouin-Wigner expansion and further\nregularize the theory on a cubic lattice. The monopole charges obtained from\nthe low-energy Hamiltonian can be reconciled with the number of Fermi arcs on\nthe lattice which we find numerically.",
        "positive": "Self-assembly mechanisms of short atomic chains on single layer graphene\n  and boron nitride: Nucleation and growth mechanisms of short chains of carbon atoms on\nsingle-layer, hexagonal boron nitride (h-BN), and short BN chains on graphene\nare investigated using first-principles plane wave calculations. Our analysis\nstarts with the adsorption of a single carbon ad-atom and examines its\nmigrations. Once a C$_2$ nucleates on h-BN, the insertion of each additional\ncarbon at its close proximity causes a short segment of carbon atomic chain to\ngrow by one atom at at a time in a quaint way: The existing chain leaves its\ninitial position and subsequently is attached from its bottom end to the top of\nthe carbon ad-atom. The electronic, magnetic and structural properties of these\nchains vertically adsorbed to h-BN depend on the number of carbon atoms in the\nchain, such that they exhibit an even-odd disparity. An individual carbon chain\ncan also modify the electronic structure with localized states in the wide band\ngap of h-BN. As a reverse situation we examined the growth of short BN atomic\nchains on graphene, which attribute diverse properties depending on whether B\nor N is the atom bound to the substrate. These results together with ab-initio\nmolecular dynamics simulations of the growth process reveal the interesting\nself-assembly behavior of the grown chains. Furthermore, we find that these\natomic chains enhance the chemical activity of h-BN and graphene sheets by\ncreating active sites for the bonding of various ad-atoms and can act as\npillars between two and multiple sheets of these honeycomb structures leaving\nwider spacing between them to achieve high capacity storage of specific\nmolecules."
    },
    {
        "anchor": "Energy Partitioning of Tunneling Currents into Luttinger Liquids: Tunneling of electrons of definite chirality into a quantum wire creates\ncounterpropagating excitations, carrying both charge and energy. We find that\nthe partitioning of energy is qualitatively different from that of charge. The\npartition ratio of energy depends on the excess energy of the tunneling\nelectrons (controlled by the applied bias) and on the interaction strength\nwithin the wire (characterized by the Luttinger liquid parameter $\\kappa$),\nwhile the partitioning of charge is fully determined by $\\kappa$. Moreover,\nunlike for charge currents, the partitioning of energy current should manifest\nitself in $dc$ experiments on wires contacted by conventional (Fermi-liquid)\nleads.",
        "positive": "Interplay of quantum spin Hall effect and spontaneous time-reversal\n  symmetry breaking in electron-hole bilayers II: Zero-field topological\n  superconductivity: It has been proposed that band-inverted electron-hole bilayers support a\nphase transition from an insulating phase with spontaneously broken\ntime-reversal symmetry to a quantum spin Hall insulator phase as a function of\nincreasing electron and hole densities. Here, we show that in the presence of\nproximity-induced superconductivity it is possible to realize Majorana zero\nmodes in the time-reversal symmetry broken phase in the absence of magnetic\nfield. We develop an effective low-energy theory for the system in the presence\nof time-reversal symmetry breaking order parameter to obtain analytically the\nMajorana zero modes and we find a good agreement between the numerical and\nanalytical results in the limit of weakly broken time-reversal symmetry. We\nshow that the Majorana zero modes can be detected in\nsuperconductor/time-reversal symmetry broken insulator/superconductor Josephson\njunctions through the measurement of a $4\\pi$ Josephson current. Finally, we\ndemonstrate that the Majorana fusion-rule detection is feasible by utilizing\nthe gate voltage dependence of the spontaneous time-reversal symmetry breaking\norder parameter."
    },
    {
        "anchor": "Logical XOR gate response in a quantum interferometer: A spin dependent\n  transport: We examine spin dependent transport in a quantum interferometer composed of\nmagnetic atomic sites based on transfer matrix formalism. The interferometer,\nthreaded by a magnetic flux $\\phi$, is symmetrically attached to two\nsemi-infinite one-dimensional (1D) non-magnetic electrodes, namely, source and\ndrain. A simple tight-binding model is used to describe the bridge system, and,\nhere we address numerically the conductance-energy and current-voltage\ncharacteristics as functions of the interferometer-to-electrode coupling\nstrength, magnetic flux and the orientation of local the magnetic moments\nassociated with each atomic site. Quite interestingly it is observed that, for\n$\\phi=\\phi_0/2$ ($\\phi_0=ch/e$, the elementary flux-quantum) a logical XOR gate\nlike response is observed, depending on the orientation of the local magnetic\nmoments associated with the magnetic atoms in the upper and lower arms of the\ninterferometer, and it can be changed by an externally applied gate magnetic\nfield. This aspect may be utilized in designing a spin based electronic logic\ngate.",
        "positive": "Topological entanglement entropy in the second Landau level: The entanglement entropy of the incompressible states of a realistic quantum\nHall system in the second Landau level are studied by direct diagonalization.\nThe subdominant term to the area law, the topological entanglement entropy,\nwhich is believed to carry information about topologic order in the ground\nstate, was extracted for filling factors nu = 12/5 and nu = 7/3. While it is\ndifficult to make strong conclusions about nu = 12/5, the nu = 7/3 state\nappears to be very consistent with the topological entanglement entropy for the\nk=4 Read-Rezayi state. The effect of finite thickness corrections to the\nCoulomb potential used in the direct diagonalization are also systematically\nstudied."
    },
    {
        "anchor": "Synthesizing Weyl semimetals in weak topological insulator and\n  topological crystalline insulator multilayers: We propose a different route to time-reversal invariant Weyl semimetals\nemploying multilayer heterostructures comprising ordinary \"trivial\" insulators\nand nontrivial insulators with \\textit{pairs} of protected Dirac cones on the\nsurface. We consider both the case of weak topological insualtors, where\nsurface Dirac cones are pinned to time-reversal invariant momenta, and of\ntopological crystalline insulators with unpinned surface Dirac cones. For both\nrealizations we explain phenomenologically how the proposed construction leads\nto the emergence of a Weyl semimetal phase. We further formulate effective\nlow-energy models for which we prove the existence of semimetallic phases with\nfour isolated Weyl points. Finally, we discuss how the proposed design can be\nrealized experimentally with state-of-the-art technologies.",
        "positive": "Effect of Exchange Interaction on Magnetic Thermal Fluctuation and Spin\n  Susceptibility: The expression of the thermal fluctuation parameter in the stochastic\nLandau-Lifshitz-Gilbert equation has been derived from a fundamental quantum\ntheory of spins and phonons, in which the exchange interaction between nearest\natoms has been included. Our studies show that the thermal fluctuation\ndecreases exponentially with increasing exchange interaction. The non-uniform\nfluctuation of local spins make the spin susceptibility much different from the\nresult derived by the macro-spin model or single spin model. The related spin\nsusceptibility depends not only on the strength of exchange interaction, but\nalso on the lattice structure. The non-uniform fluctuation can lead to an extra\nbroadening of the resonance line width along with the broadening arisen from\nthe Gilbert damping."
    },
    {
        "anchor": "An effective-charge model for the trapping of impurities of fluids in\n  channels with nanostructured walls: We present model equations for the trapping and accumulation of particles in\na short cylindrical channel with nanostructured inner walls when a fluid passes\nthrough, carrying a moderate load of impurities. The basic ingredient of the\nmodel is the introduction of a phenomenological \"effective-charge density\" of\nthe walls, related to the electrical charges exposed in the nanotexture, and\nwhich is gradually reduced as the flow runs through the channel and the trapped\nimpurities cover the internal walls. By solving the proposed equations, three\nregimes are predicted for the channel: a linear or clean-filter regime, a\nlogarithmic or half-saturation regime, and the saturation limit. It is proposed\nthat experimentally testing these regimes may help to understand the enhanced\ntrapping capability observed in many diverse nanotextured channel structures.",
        "positive": "Quantum-to-classical crossover of quasi-bound states in open quantum\n  systems: In the semiclassical limit of open ballistic quantum systems, we demonstrate\nthe emergence of instantaneous decay modes guided by classical escape faster\nthan the Ehrenfest time. The decay time of the associated quasi-bound states is\nsmaller than the classical time of flight. The remaining long-lived quasi-bound\nstates obey random-matrix statistics, renormalized in compliance with the\nrecently proposed fractal Weyl law for open systems [W. T. Lu, S. Sridhar, and\nM. Zworski, Phys. Rev. Lett. 91, 154101 (2003)]. We validate our theory\nnumerically for a model system, the open kicked rotator."
    },
    {
        "anchor": "Ab Initio Calculations of the Walls Shear Strength of Carbon Nanotubes: The dependence of the energy of interwall interaction in double-walled carbon\nnanotubes (DWNT) on the relative position of walls has been calculated using\nthe density functional method. This dependence is used to evaluate forces that\nare necessary for the relative telescopic motion of walls and to calculate the\nshear strength of DWNT for the relative sliding of walls along the nanotube\naxis and for their relative rotation about this axis. The possibility of\nexperimental verification of the obtained results is discussed.",
        "positive": "Topological photon pairs in a superconducting quantum metamaterial: Recent discoveries in topological physics hold a promise for disorder-robust\nquantum systems and technologies. Topological states provide the crucial\ningredient of such systems featuring increased robustness to disorder and\nimperfections. Here, we use an array of superconducting qubits to engineer a\none-dimensional topologically nontrivial quantum metamaterial. By performing\nmicrowave spectroscopy of the fabricated array, we experimentally observe the\nspectrum of elementary excitations. We find not only the single-photon\ntopological states but also the bands of exotic bound photon pairs arising due\nto the inherent anharmonicity of qubits. Furthermore, we detect the signatures\nof the two-photon bound edge-localized state which hints towards\ninteraction-induced localization in our system. Our work demonstrates an\nexperimental implementation of the topological model with attractive\nphoton-photon interaction in a quantum metamaterial."
    },
    {
        "anchor": "Intermolecular interaction enhances thermoelectric performance of\n  molecular junctions: Novel organic materials formed from functional molecules are attractive for\nvarious nanoelectronic applications because they are environmentally friendly,\nwidely available and inexpensive. Recent advancement in bottom-up fabrication\nmethods has made it possible to design and synthesis functional molecules with\ndesired functionalities and engineer their properties precisely. This requires\ndeeper understanding of if the properties of building blocks e.g. single\nmolecules can be translated to many molecule junctions in the form of\nself-assembled monolayers (SAM). Therefore, understanding the effect of\nintermolecular interaction becomes important. In this paper, we study the\neffect of intermolecular interactions on the charge transport and\nthermoelectric properties of junctions formed by parallel molecules between\nmetallic electrodes. We demonstrate that the electrical conductance and Seebeck\ncoefficient are enhanced simultaneously leading to more than an order of\nmagnitude enhancement of power factor as a result of intermolecular coupling\nbetween two molecules of the same kind or different. This strategy can be used\nto improve the thermoelectric performance of SAMs by engineering their packing\ndensity.",
        "positive": "Generalized Tunneling Model for TLS in amorphous materials and its\n  predictions for their dephasing and the noise in superconducting\n  microresonators: We formulate the generalized tunneling model for two level systems in\ninsulators that takes into account the interaction between them and a slow\npower law dependence of their density of states. We show that the predictions\nof this model are in a perfect agreement with the recent studies of the noise\nin high quality superconducting resonators. The predictions also agree with the\ntemperature dependence of the TLS dephasing rates observed in phase qubits.\nBoth observations are impossible to explain in the framework of the standard\ntunneling model of TLS. We discuss the origin of the universal dimensionless\nparameter that controls the interaction between TLS in glasses and show that it\nis consistent with the assumptions of the model."
    },
    {
        "anchor": "Two-Beam Spin Noise Spectroscopy: We propose a method of two-beam spin noise spectroscopy to test the spin\ntransport at equilibrium via analysis of correlations between time-shifted spin\nfluctuations at different space locations. This method allows one to determine\nthe strength of spin-orbit interaction and spin relaxation time and separate\nspin noise of conducting electrons from the background noise of localized\nelectrons. We formulate a theory of two-beam spin noise spectroscopy in\nsemiconductor wires with Bychkov-Rashba spin-orbit interaction taking into\naccount several possible spin relaxation channels and finite size of laser\nbeams. Our theory predicts a peak shift with respect to the Larmor frequency to\nhigher or lower frequencies depending on the strength of spin orbit interaction\nand distance between the beams. The two-beam spin noise spectroscopy could find\napplications in experimental studies of semiconductors, emergent materials and\nmany other systems.",
        "positive": "Extended Hubbard model describing small multi-dot arrays in bilayer\n  graphene: We set up and parametrize a Hubbard model for interacting quantum dots in\nbilayer graphene and study double dots as the smallest multi-dot system. We\ndemonstrate the tunability of the spin and valley multiplets, Hubbard\nparameters, and effective exchange interaction by electrostatic gate potentials\nand the magnetic field. Considering both the long- and short-range Coulomb\ninteraction, we map out the various spin and valley multiplets and calculate\ntheir energy gaps for different dot sizes and inter-dot separations. For\nhalf-filling and large valley splittings, we derive and parametrize an\neffective Heisenberg model for the quantum dot spins."
    },
    {
        "anchor": "On the solenoidal heat-flux in quasi-ballistic thermal conduction: The Boltzmann transport equation for phonons is recast directly in terms of\nthe heat-flux by means of iteration followed by truncation at the second order\nin the spherical harmonic expansion of the distribution function. This\nprocedure displays the heat-flux in an explicitly coordinate-invariant form,\nand leads to a natural decomposition into two components, namely the solenoidal\ncomponent in addition to the usual irrotational component. The solenoidal\nheat-flux is explicitly shown to arise by applying the heat-flux equation to a\nright-circular cylinder. These findings are important in the context of phonon\nresonators that utilize the strong quasi-ballistic thermal transport reported\nrecently in silicon membranes at room temperature.",
        "positive": "Four wave mixing spectroscopy of quantum dot molecules: We study theoretically the nonlinear four wave mixing (FWM) response of an\nensemble of coupled pairs of quantum dots (quantum dot molecules). We discuss\nthe shape of the FWM echo signal depending on the parameters of the ensemble:\nthe statistics of transition energies and the degree of size correlations\nbetween the dots forming the molecules."
    },
    {
        "anchor": "Surface States and Arcless Angles in Twisted Weyl Semimetals: Fermi arc states are features of Weyl semimetal (WSM) surfaces which are\nrobust due to the topological character of the bulk band structure. We\ndemonstrate that Fermi arcs may undergo profound restructurings when surfaces\nof different systems with a well-defined twist angle are tunnel-coupled. The\ntwisted WSM interface supports a moir\\'e pattern which may be approximated as a\nperiodic system with large real-space unit cell. States bound to the interface\nemerge, with interesting consequences for the magneto-oscillations expected\nwhen a magnetic field is applied perpendicular to the system surfaces. As the\ntwist angle passes through special \"arcless angles', for which open Fermi arc\nstates are absent at the interface, Fermi loops of states confined to the\ninterface may break off, without connecting to bulk states of the WSM. We argue\nthat such states have interesting resonance signatures in the optical\nconductivity of the system in a magnetic field perpendicular to the interface.",
        "positive": "Revealing Majorana Fermion states in a superfluid of cold atoms subject\n  to a harmonic potential: We here explore Majorana Fermion states in an s-wave superfluid of cold atoms\nin the presence of spin-orbital coupling and an additional harmonic potential.\nThe superfluid boundary is induced by a harmonic trap. Two locally separated\nMajorana Fermion states are revealed numerically based on the self-consistent\nBogoliubov-de Gennes equations. The local density of states are calculated,\nthrough which the signatures of Majorana excitations may be indicated\nexperimentally."
    },
    {
        "anchor": "Spin splitting induced in a superconductor by an antiferromagnetic\n  insulator: Inspired by recent feats in exchange coupling antiferromagnets to an adjacent\nmaterial, we demonstrate the possibility of employing them for inducing spin\nsplitting in a superconductor, thereby avoiding the detrimental, parasitic\neffects of ferromagnets employed to this end. We derive the Gor'kov equation\nfor the matrix Green's function in the superconducting layer, considering a\nmicroscopic model for its disordered interface with a two-sublattice magnetic\ninsulator. We find that an antiferromagnetic insulator with effectively\nuncompensated interface induces a large, disorder-resistant spin splitting in\nthe adjacent superconductor. In addition, we find contributions to the\nself-energy stemming from the interfacial disorder. Within our model, these\nmimic impurity and spin-flip scattering, while another breaks the symmetries in\nparticle-hole and spin spaces. The latter contribution, however, drops out in\nthe quasi-classical approximation and thus, does not significantly affect the\nsuperconducting state.",
        "positive": "Determination of Penetration Depth of Transverse Spin Current in\n  Ferromagnetic Metals by Spin Pumping: Spin pumping in nonmagnetic/ferromagnetic metal multilayers is studied both\ntheoretically and experimentally. We show that the line widths of the\nferromagnetic resonance (FMR) spectrum depend on the thickness of the\nferromagnetic metal layers, which must not be in resonance with the oscillating\nmagnetic field. We also show that the penetration depths of the transverse spin\ncurrent in ferromagnetic metals can be determined by analyzing the line widths\nof their FMR spectra. The obtained penetration depths in NiFe, CoFe and CoFeB\nwere 3.7 [nm], 2.5 [nm] and 12.0 [nm], respectively."
    },
    {
        "anchor": "Noise spectrum of a quantum dot-resonator lasing circuit: Single-electron tunneling processes through a double quantum dot can induce a\nlasing state in an electromagnetic resonator which is coupled coherently to the\ndot system. Here we study the noise properties of the transport current in the\nlasing regime, i.e., both the zero-frequency shot noise as well as the noise\nspectrum. The former shows a remarkable super-Poissonian behavior when the\nsystem approaches the lasing transition, but sub-Poissonian behavior deep in\nthe lasing state. The noise spectrum contains information about the coherent\ndynamics of the coupled dot-resonator system. It shows pronounced structure at\na frequency matching that of the resonator due to the excitation of photons.\nFor strong interdot Coulomb interaction we find asymmetries in the\nauto-correlation noise spectra of the left and right junctions, which we trace\nback to asymmetries in the incoherent tunneling channels.",
        "positive": "Magnetization dynamics and reversal of two-dimensional magnets: Micromagnetics simulation based on the classical Landau-Lifshitz-Gilbert\n(LLG) equation has long been a powerful method for modeling magnetization\ndynamics and reversal of three-dimensional (3D) magnets. For two-dimensional\n(2D) magnets, the magnetization reversal always accompanies the collapse of the\nmagnetization even at low temperatures due to intrinsic strong spin\nfluctuation. We propose a micromagnetic theory that explicitly takes into\naccount the rapid demagnetization and remagnetization dynamics of 2D magnets\nduring magnetization reversal. We apply the theory to a single-domain magnet to\nillustrate fundamental differences in magnetization trajectories and reversal\ntimes for 2D and 3D magnets."
    },
    {
        "anchor": "Thermal entanglement in superconducting quantum-interference-device\n  qubits coupled to cavity field: In this paper, we investigate thermal entanglement in a\nsuperconducting-quantum-interference-device qubit coupled to a cavity field. We\nshow that the entanglement can be manipulated by varying temperature and an\neffective controlling parameter $B$ which depends on the external field and\ncharacteristic parameters of the system. We find that there exists a critical\nvalue of the controlling parameter $B_c$. Under a fixed temperature, increasing\n$B$ can increase entanglement in the regime of $B<B_c$, while the entanglement\ndecreases with increasing $B$ in the regime of $B>B_c$.",
        "positive": "Bulk-impurity induced noise in large-area epitaxial thin films of\n  topological insulators: We report a detailed study on low-frequency 1/f-noise in large-area\nmolecular-beam epitaxy grown thin (10 nm) films of topological insulators as a\nfunction of temperature, gate voltage, and magnetic field. When the Fermi\nenergy is within the bulk valence band, the temperature dependence reveals a\nclear signature of generation-recombination noise in the defect states in the\nbulk band gap. However, when the Fermi energy is tuned to the bulk band gap,\nthe gate voltage dependence of noise shows that the resistance fluctuations in\nsurface transport are caused by correlated mobility-number density fluctuations\ndue to the activated defect states present in the bulk of the topological\ninsulator crystal with a density of D$_{it}=3.2\\times10^{17}$ cm$^2$eV$^{-1}$.\nIn the presence of a magnetic field, noise in these materials follows a\nparabolic dependence, which is qualitatively similar to mobility and\ncharge-density fluctuation noise in non-degenerately doped trivial\nsemiconductors. Our studies reveal that even in thin films of (Bi,Sb)$_2$Te$_3$\nwith thickness as low as 10 nm, the intrinsic bulk defects are the dominant\nsource of noise."
    },
    {
        "anchor": "Thermal transport, geometry, and anomalies: The relation between thermal transport and gravity was highlighted in the\nseminal work by Luttinger in 1964, and has been extensively developed to\nunderstand thermal transport, most notably the thermal Hall effect. Here we\nreview the novel concepts that relate thermal transport, the geometry of\nspace-time and quantum field theory anomalies. We give emphasis to the\ncross-pollination between emergent ideas in condensed matter, notably Weyl and\nDirac semimetals, and the understanding of gravitational and scale anomalies\nstemming from high-energy physics. We finish by relating to recent experimental\nadvances and presenting a perspective of several open problems.",
        "positive": "Large circular photogalvanic effect in non-centrosymmetric magnetic Weyl\n  semimetal CeAlSi: The recent discovery of the Weyl semimetal CeAlSi with simultaneous breaking\nof inversion and time-reversal symmetries has opened up new avenues for\nresearch into the interaction between light and topologically protected bands.\nIn this work, we present a comprehensive examination of shift current and\ninjection current responsible for the circular photogalvanic effect in CeAlSi\nusing first-principles calculations. Our investigation identifies a significant\ninjection current of 1.2 mA/V$^2$ over a broad range in the near-infrared\nregion of the electromagnetic spectrum, exceeding previously reported findings.\nIn addition, we explored several externally controllable parameters to further\nenhance the photocurrent. A substantial boost in the injection current is\nobserved when applying uniaxial strain along the $c$-axis of the crystal $-$ a\n5% strain results in a remarkable 64% increment. The exceptional photocurrent\nresponse in CeAlSi suggests that magnetic non-centrosymmetric Weyl semimetals\nmay provide promising opportunities for novel photogalvanic applications."
    },
    {
        "anchor": "Plasmon modes of coupled quantum Hall edge channels in the presence of\n  disorder-induced tunneling: Coupled quantum Hall edge channels show intriguing non-trivial modes, for\nexample, charge and neutral modes at Landau level filling factors 2 and 2/3. We\npropose an appropriate and effective model with Coulomb interaction and\ndisorder-induced tunneling characterized by coupling capacitances and tunneling\nconductances, respectively. This model explains how the transport eigenmodes,\nwithin the interaction- and disorder-dominated regimes, change with the\ncoupling capacitance, tunneling conductance, and measurement frequency. We\npropose frequency- and time-domain transport experiments, from which eigenmodes\ncan be determined using this model.",
        "positive": "Charge transport in two dimensions limited by strong short-range\n  scatterers: Going beyond parabolic dispersion and Born approximation: We investigate the conductivity of charge carriers confined to a\ntwo-dimensional system with the non-parabolic dispersion $k^N$ with $N$ being\nan arbitrary natural number. A delta-shaped scattering potential is assumed as\nthe major source of disorder. We employ the exact solution of the\nLippmann-Schwinger equation to derive an analytical Boltzmann conductivity\nformula valid for an arbitrary scattering potential strength. The range of\napplicability of our analytical results is assessed by a numerical study based\non the finite size Kubo formula. We find that for any $N>1$, the conductivity\ndemonstrates a linear dependence on the carrier concentration in the limit of a\nstrong scattering potential strength. This finding agrees with the conductivity\nmeasurements performed recently on chirally stacked multilayer graphene where\nthe lowest two bands are non-parabolic and the adsorbed hydrocarbons might act\nas strong short-range scatterers."
    },
    {
        "anchor": "Metallic-insulator phase transitions in the extended Harper model: In this work we investigate the transport properties of non-relativistic\nquantum particles on incommensurate multilayered structures with the\nthicknesses $w_n$ of the layers following an extended Harper model given by\n$w_n = w_0 |\\cos(\\pi a n^{\\nu})|$. For the normal incidence case, which means\nan one-dimensional system, we obtained that for a specific range of energy, it\nis possible to see a metallic-insulator transition with the exponent $\\nu$. A\nmetallic phase is supported for $\\nu<1$. We also obtained that for the specific\nvalue $\\nu=1$ there is an alternation between metallic and insulator phases as\nwe change the disorder strength $w_0$. When we integrate out all incidence\nangles, which means a two-dimensional system, the metallic-insulator transition\ncan be seen for much larger range of energy compared to the normal incidence\ncase.",
        "positive": "Realization of high-capacity hydrogen storage using carbon atomic\n  chains: the role of terminations: The capacity of carbon atomic chains with different terminations for hydrogen\nstorage is studied using first-principles density functional theory\ncalculations. Unlike the physisorption of H2 on the H-terminated chain, we show\nthat two Li (Na) atoms each capping one end of the carbon chain can hold ten H2\nmolecules with optimal binding energies for room temperature storage. The\nhybridization of the Li 2p states with the H2 sigma orbitals contributes to the\nH2 adsorption. However, the binding mechanism of the H2 molecules on Na arises\nonly from the polarization interaction between the charged Na atom and the H2.\nMoreover, additional H2 molecules can be bound to the carbon atoms at the chain\nends due to the charge transfer between Li 2s2p (Na 3s) and C 2p states.\nImportantly, dimerization of these isolated metal-capped chains does not affect\nthe hydrogen binding energy significantly. In addition, a single chain can be\nstabilized effectively by termination on the C60 clusters. With a hydrogen\nuptake of > 10 wt % on Li-coated C60-Cn-C60 (n = 5, 8), the Li12C60-Cn-Li12C60\ncomplex, without reducing the number of adsorbed H2 molecules per Li, can serve\nas better building blocks of polymers than the (Li12C60)2 dimer. These findings\nsuggest a new route to design cluster-assembled storage materials based on\nterminated sp carbon chains."
    },
    {
        "anchor": "Voltage percolation thresholds evidenced in the electrical behaviour of\n  different nanostructures: Percolation phenomena are investigated and discussed in three kinds of\nnanostructures: first two are nanocrystalline silicon-based systems, Si\nnanodots embedded in amorphous SiO2 matrix and porous silicon formed by an\noxidized nanowire network, and the third consisting of a multi-walled carbon\nnanotube network embedded in amorphous SiN. The current-voltage characteristics\nmeasured on first two systems present voltage percolation thresholds with the\nsame shape - a saturation plateau region of the current, followed by an abrupt\nincrease. The current-voltage and conductance-voltage curves measured on\nmulti-walled carbon nanotube network embedded in amorphous SiN present\nnon-periodic and temperature independent oscillations. These oscillations are\ninterpreted as voltage percolation thresholds.",
        "positive": "Ladder network as a mesoscopic switch: An exact result: We investigate the possibilities of a tight binding ladder network as a\nmesoscopic switching device. Several cases have been discussed in which any one\nor both the arms of the ladder can assume random, ordered or quasiperiodic\ndistribution of atomic potentials. We show that, for a special choice of the\nHamiltonian parameters it is possible to prove exactly the existence of\nmobility edges in such a system, which plays a central role in the switching\naction. We also present numerical results for the two-terminal conductance of a\ngeneral model of a quasiperiodically grown ladder which support the general\nfeatures of the electron states in such a network. The analysis might be\nhelpful in fabricating mesoscopic or DNA switching devices."
    },
    {
        "anchor": "Non-Abelian statistics and topological quantum information processing in\n  1D wire networks: Topological quantum computation provides an elegant way around decoherence,\nas one encodes quantum information in a non-local fashion that the environment\nfinds difficult to corrupt. Here we establish that one of the key\noperations---braiding of non-Abelian anyons---can be implemented in\none-dimensional semiconductor wire networks. Previous work [Lutchyn et al.,\narXiv:1002.4033 and Oreg et al., arXiv:1003.1145] provided a recipe for driving\nsemiconducting wires into a topological phase supporting long-sought particles\nknown as Majorana fermions that can store topologically protected quantum\ninformation. Majorana fermions in this setting can be transported, created, and\nfused by applying locally tunable gates to the wire. More importantly, we show\nthat networks of such wires allow braiding of Majorana fermions and that they\nexhibit non-Abelian statistics like vortices in a p+ip superconductor. We\npropose experimental setups that enable the Majorana fusion rules to be probed,\nalong with networks that allow for efficient exchange of arbitrary numbers of\nMajorana fermions. This work paves a new path forward in topological quantum\ncomputation that benefits from physical transparency and experimental realism.",
        "positive": "Quantum Sensing of Single Phonons via Phonon Drag in Two-Dimensional\n  Materials: The capacity to electrically detect phonons, ultimately at the single-phonon\nlimit, is a key requirement for many schemes for phonon-based quantum\ncomputing, so-called quantum phononics. Here, we predict that by exploiting the\nstrong coupling of their electrons to surface-polar phonons, van der Waals\nheterostructures can offer a suitable platform for phonon sensing, capable of\nresolving energy transfer at the single-phonon level. The geometry we consider\nis one in which a drag momentum is exerted on electrons in a graphene layer, by\na single out-of-equilibrium phonon in a dielectric layer of hexagonal boron\nnitride, giving rise to a measurable induced voltage ($V_{\\rm drag}$). Our\nnumerical solution of the Boltzmann Transport Equation shows that this drag\nvoltage can reach a level of a few hundred microvolts per phonon, well above\nexperimental detection limits. Furthermore, we predict that $V_{\\rm drag}$\nshould be highly insensitive to the mobility of carriers in the graphene layer\nand to increasing the temperature to at least 300 K, offering the potential of\na versatile material platform for single-phonon sensing."
    },
    {
        "anchor": "Temperature dependence of Coulomb drag between finite-length quantum\n  wires: We evaluate the Coulomb drag current in two finite-length\nTomonaga-Luttinger-liquid wires coupled by an electrostatic backscattering\ninteraction. The drag current in one wire shows oscillations as a function of\nthe bias voltage applied to the other wire, reflecting interferences of the\nplasmon standing waves in the interacting wires. In agreement with this\npicture, the amplitude of the current oscillations is reduced with increasing\ntemperature. This is a clear signature of non-Fermi-liquid physics because for\ncoupled Fermi liquids the drag resistance is always expected to increase as the\ntemperature is raised.",
        "positive": "Nonequilibirum noise spectrum and Coulomb-blockade-assisted Rabi\n  interference in a double-dot Aharonov-Bohm interferometer: We investigate the charge-states coherence underlying the nonequilibirum\ntransport through a spinless double-dot Aharonov-Bohm (AB) interferometer. Both\nthe current noise spectrum and real-time dynamics are evaluated with the\nwell-established dissipaton-equation-of-motion method. The resulted spectrums\nshow the characteristic peaks and dips, arising from coherent Rabi oscillation\ndynamics, with the environment-assisted indirect inter-dot tunnel coupling\nmechanism. The observed spectroscopic features are in a quantitative agreement\nto the real-time dynamics of the reduced density matrix off-diagonal element\nbetween two charge states. As the aforementioned mechanism, these\ncharacteristics of coherence are very sensitive to the AB phase. While this is\ngenerally true for cross-correlation spectrum, the total circuit noise spectrum\nthat is experimentally more accessible shows remarkably rich interplay between\nvarious mechanisms. The most important finding of this work is the existence of\nCoulomb-blockade-assisted Rabi interference, with very distinct signatures\narising from the interplay between the AB interferometer and the interdot\nCoulomb interaction induced Fano resonance."
    },
    {
        "anchor": "Rotational dynamics and friction in double-walled carbon nanotubes: We report a study of the rotational dynamics in double-walled nanotubes using\nmolecular dynamics simulations and a simple analytical model reproducing very\nwell the observations. We show that the dynamic friction is linear in the\nangular velocity for a wide range of values. The molecular dynamics simulations\nshow that for large enough systems the relaxation time takes a constant value\ndepending only on the interlayer spacing and temperature. Moreover, the\nfriction force increases linearly with contact area, and the relaxation time\ndecreases with the temperature with a power law of exponent $-1.53 \\pm 0.04$.",
        "positive": "Ballistic Thermal Transport at Sub-10 nm Laser-Induced Hot Spots in GaN\n  Crystal: Gallium nitride (GaN) is a typical wide-bandgap semiconductor with a critical\nrole in a wide range of electronic applications. Ballistic thermal transport at\nnanoscale hotspots will greatly reduce the performance of a device when its\ncharacteristic length reaches the nanometer scale, due to heat dissipation. In\nthis work, we developed a tip-enhanced Raman thermometry approach to study\nballistic thermal transport within the range of 10 nm in GaN, simultaneously\nachieving laser heating and measuring the local temperature. The Raman results\nshowed that the temperature increase from an Au-coated tip-focused hotspot was\nup to two times higher (40 K) than that in a bare tip-focused region (20 K). To\nfurther investigate the possible mechanisms behind this temperature difference,\nwe performed electromagnetic simulations to generate a highly focused heating\nfield, and observed a highly localized optical penetration, within a range of\n10 nm. The phonon mean free path (MFP) of the GaN substrate could thus be\ndetermined by comparing the numerical simulation results with the\nexperimentally measured temperature increase which was in good agreement with\nthe average MFP weighted by the mode-specific thermal conductivity, as\ncalculated from first-principles simulations. Our results demonstrate that the\nphonon MFP of a material can be rapidly predicted through a combination of\nexperiments and simulations, which can find wide application in the thermal\nmanagement of GaN-based electronics."
    },
    {
        "anchor": "Manipulating Ferrimagnets by Fields and Currents: Ferrimagnets (FIMs) can function as high-frequency antiferromagnets while\nbeing easy to detect as ferromagnets, offering unique opportunities for\nultrafast device applications. While the physical behavior of FIMs near the\ncompensation point has been widely studied, there lacks a generic understanding\nof FIMs where the ratio of sublattice spins can vary freely between the\nferromagnetic and antiferromagnetic limits. Here we investigate the physical\nproperties of a model two-sublattice FIM manipulated by static magnetic fields\nand current-induced torques. By continuously varying the ratio of sublattice\nspins, we clarify how the dynamical chiral modes in an FIM are intrinsically\nconnected to their ferro- and antiferromagnetic counterparts, which reveals\nunique features not visible near the compensation point. In particular, we find\nthat current-induced torques can trigger spontaneous oscillation of the\nterahertz exchange mode. Compared with its realization in antiferromagnets, a\nspin-torque oscillator using FIMs not only has a reduced threshold current\ndensity but also can be self-stabilized, obviating the need for dynamic\nfeedback.",
        "positive": "Fluctuation conductivity of disordered superconductors in magnetic\n  fields: We calculate fluctuation corrections to the longitudinal conductivity of\ndisordered superconductors subject to an external magnetic field. We derive\nanalytic expressions that are valid in the entire metallic part of the\ntemperature-magnetic field phase diagram as long as the effect of the magnetic\nfield on the spin degrees of freedom of the electrons may be neglected. Our\ncalculations are based on a kinetic equation approach. For the special case of\nsuperconducting films and wires in parallel magnetic fields we perform a\ndetailed comparison with results that were previously obtained with\ndiagrammatic perturbation theory in the imaginary time formalism. As an\napplication, we study the fluctuation conductivity of films in tilted magnetic\nfields with a special focus on the low-temperature regime. We present a\ndetailed discussion of the phenomenon of the non-monotonous magnetoresistance\nand find that it displays a pronounced dependence on the tilting angle."
    },
    {
        "anchor": "Dephasing in quantum dot molecules via exciton-acoustic phonon coupling: We develop a theory of the linear optical spectrum of excitons in quantum dot\nmolecules, including the effect of exciton-phonon coupling beyond the Markov\nlimit. The model reproduces the general trend of the zero-phonon line\nbroadening as a function of interdot distance, that were recently measured. The\nunexpectedly broad linewidths and their large variation are explained in terms\nof both the non-Markov nature of the coupling and of the matching of the phonon\nwavelength to the interdot distance.",
        "positive": "Spin oscillations of a single-mode polariton system driven by a plane\n  wave: Theoretical study is performed of a single-mode polariton system with linear\ncoupling of spin components. When combined with an ordinary two-particle\ninteraction, the spin coupling involves a spontaneous symmetry breaking\naccompanied by a switch from linear to circular polarization under resonant\ndriving. The asymmetric steady states can also lose stability, giving way to\noscillatory and chaotic dynamics. Here, we explore a continuous transformation\nbetween the multistable regime, where the system is steady and locked in phase\nto the pump but has a broken spin symmetry, and full-span oscillations of the\ncircular-polarization degree, owing to which the symmetry is effectively\nreestablished. Such oscillations are analogous to the intrinsic Josephson\neffect and prove to be robust against arbitrarily strong perturbations.\nTransitional phenomena include the Hopf bifurcation, spin bistability of limit\ncycles, and continuous transitions to and from dynamical chaos through series\nof period doubling/halving events."
    },
    {
        "anchor": "Model of the thermoelectric properties of anisotropic organic\n  semiconductors: A model of charge hopping transport that accounts for anisotropy of localized\nstates and Coulomb interaction between charges is proposed. For the anisotropic\nlocalized states the degree of orientation relates exponentially to the ratio\nof conductivities in parallel and perpendicular directions, while the ratio of\nSeebeck coefficients stays nearly unaffected. However, the ratio of Seebeck\ncoefficients increases if Coulomb interaction is screened stronger in a\ndirection parallel to the predominant orientation of the localized states. This\nimplies two different physical mechanisms responsible for the anisotropy of\nthermoelectric properties in the hopping regime: electronic state localization\nfor conductivities, and screening for Seebeck coefficients. This provides\nexplanation for recent experimental findings on tensile drawn and ribbed\npolymer films.",
        "positive": "Energy levels and far-infrared spectroscopy for two electrons in a\n  semiconductor nanoring: The effects of electron-electron interaction of a two-electron nanoring on\nthe energy levels and far-infrared (FIR) spectroscopy have been investigated\nbased on a model calculation which is performed within the exactly numerical\ndiagonalization. It is found that the interaction changes the energy spectra\ndramatically, and also shows significant influence on the FIR spectroscopy. The\ncrossings between the lowest spin-singlet and triplet states induced by the\ncoulomb interaction are clearly revealed. Our results are related to the\nexperiment recently carried out by A. Lorke et al. [Phys. Rev. Lett. 84, 2223\n(2000)]."
    },
    {
        "anchor": "Circular dichroism in non-chiral metal halide perovskites: We demonstrate theoretically that non-chiral perovskite layers can exhibit\ncircular dichroism (CD) in the absence of a magnetic field and without chiral\nactivation by chiral molecules. The effect is shown to be due to splitting of\nhelical excitonic states which can form in structures of orthorhombic or lower\nsymmetry that exhibit Rashba spin effects. The selective coupling of these\nhelical exciton states to helical light is shown to give rise to circular\ndichroism. Polarization dependent absorption is shown to occur due to the\ncombined effect of Rashba splitting, in-plane symmetry breaking, and the effect\nof the exciton momentum on its fine structure, which takes the form of Zeeman\nsplitting in an effective magnetic field. We calculate significant CD with an\nanisotropy factor of up to 30% in orthorhombic perovskite layers under\noff-normal top illumination conditions, raising the possibility of its\nobservation in non-chiral perovskite structures.",
        "positive": "Observing the nodal-line conversion determined by the relative homotopy: Directly identifying the non-Abelian nodal-line semimetals (NASM) is quite\nchallenging because nodal-line semimetals typically do not possess\ntopologically protected boundary modes. Here, by reconstructing the\ncorrespondence between the bulk states of Hermitian systems and circuit voltage\nmodes through gauge scale potential, the temporal topolectrical circuits (TTC)\nfor evidencing NASM are proposed. Following the logical progress of discovering\nNASM, we start by demonstrating the relative homotopy group of two-band models\nusing TTC, which can faithfully determine the conversion rules between the\nnodes in and out of the non-local-symmetry invariant subspace. Next, we show\nthat those rules dramatically change with the consideration of the additional\nband, historically leading to the arising of the NASM. Also, we demonstrate the\nunique non-Abelian constrained nodal configuration -- earring nodal lines. Our\nresults established NASM for further investigating topological line\ndegeneracies, and proposed TTC will be a versatile platform for exploring\nnodal-line semimetals."
    },
    {
        "anchor": "Interfacing Ultraclean Graphene with Solid-State Devices: Interfacing graphene with solid-state devices and maintaining it free of\ncontamination is a crucial step towards a functioning device, be it a\nsemiconductor structure or any other device for technological applications. We\ntake advantage of the catalytic properties of platinum metals to completely\nremove the polymer capping after the transfer of macroscopic graphene sheets to\na solid-state device. For that purpose a platinum metal coated structure is\nbrought in close proximity with the polymer capping. Subsequent annealing in\nair at a temperature between 175 and 350{\\deg}C actuates a complete catalytic\nremoval of the polymer. Finally, the platinum metal catalyst is removed\nrevealing ultra clean graphene interfaced with an arbitrary device. Experiments\nto interface macroscopic graphene layers with oxidized silicon wafers\ndemonstrate the general applicability of this approach. In repeating the\nprocedure, multi-layer graphene sheets can also be produced. Direct evidence\nfor the latter is provided by optical images of three overlapping graphene\nsheets. The exceeding level of cleanliness of the graphene is examined on the\nnanometer scale by means of low-energy electron transmission microscopy.",
        "positive": "Failure of the displaced-squeezed state for spin-boson models in the\n  thermodynamic limit: We present an analysis of a variational coherent-squeezed state that has been\ndiscussed in the literature as a potential ground state for the spin-boson\nmodel. We show that when the system-size scaling of the spin-bath coupling is\nincluded properly, all squeezing effects and non-universal physics vanish in\nthe thermodynamic limit. We also present finite-size corrections to the\nrenormalisation of the spin's coherence, showing that squeezing effects are\nalso absent to leading order in the inverse bath-size."
    },
    {
        "anchor": "Transport and semiclassical dynamics of coupled quantum dots interacting\n  with a local magnetic moment: We present a theory of magnetotransport through a system of two coupled\nelectronic orbitals, where the electron spin interacts with a (large) local\nmagnetic moment via an exchange interaction. For the physical realization of\nsuch a set-up we have in mind, for example, semiconductor quantum dots coupled\nto an ensemble of nuclear spins in the host material or molecular orbitals\ncoupled to a local magnetic moment. Using a semiclassical approximation, we\nderive a set of Ehrenfest equations of motion for the electron density matrix\nand the mean value of the external spin (Landau equations): Due to the spin\ncoupling they turn out to be nonlinear and, importantly, also coherences\nbetween electron states with different spin directions need to be considered.\nThe electronic spin-polarized leads are implemented in form of a Lindblad-type\ndissipator in the infinite bias limit. We have solved this involved dynamical\nsystem numerically for various isotropic and anisotropic coupling schemes. For\nisotropic spin coupling and spin-polarized leads we study the effect of\ncurrent-induced magnetization of the attached spin and compare this with a\nsingle quantum dot set-up. We further demonstrate that an anisotropic coupling\ncan lead to a rich variety of parametric oscillations in the average current\nreflecting the complicated interplay between the Larmor precession of the\nexternal spin and the dissipative coherent dynamics of the electron spin.",
        "positive": "Conductance of Mesoscopic Systems with Magnetic Impurities: We investigate the combined effects of magnetic impurities and applied\nmagnetic field on the interference contribution to the conductance of\ndisordered metals. We show that in a metal with weak spin-orbit interaction,\nthe polarization of impurity spins reduces the rate of electron phase\nrelaxation, thus enhancing the weak localization correction to conductivity.\nMagnetic field also suppresses thermal fluctuations of magnetic impurities,\nleading to a recovery of the conductance fluctuations. This recovery occurs\nregardless the strength of the spin-orbit interaction. We calculate the\nmagnitudes of the weak localization correction and of the mesoscopic\nconductance fluctuations at an arbitrary level of the spin polarization induced\nby a magnetic field. Our analytical results for the ``$h/e$'' Aharonov-Bohm\nconductance oscillations in metal rings can be used to extract spin and\ngyromagnetic factor of magnetic impurities from existing experimental data."
    },
    {
        "anchor": "Inelastic shot noise characteristics of nanoscale junctions from first\n  principles: We describe an implementation of ab-initio methodology to compute inelastic\nshot noise signals due to electron-vibration scattering in nanoscale junctions.\nThe method is based on the framework of non-equilibrium Keldysh Green's\nfunctions with a description of electronic structure and nuclear vibrations\nfrom density functional theory. Our implementation is illustrated with\nsimulations of electron transport in Au and Pt atomic point contacts. We show\nthat the computed shot noise characteristics of the Au contacts can be\nunderstood in terms of a simple two-site tight-binding model representing the\ntwo apex atoms of the vibrating nano-junction. We also show that the shot noise\ncharacteristics of Pt contacts exhibit more complex features associated with\ninelastic interchannel scattering. These inelastic noise features are shown to\nprovide additional information about the electron-phonon coupling and the\nmultichannel structure of Pt contacts than what is readily derived from the\ncorresponding conductance characteristics.We finally analyze a set of Au atomic\nchains of different lengths and strain conditions and provide a quantitative\ncomparison with the recent shot noise experiments reported by Kumar et al.\n[Phys. Rev. Lett. 108, 146602 (2012)].",
        "positive": "Molecular states in carbon nanotube double quantum dots: We report electrical transport measurements through a semiconducting\nsingle-walled carbon nanotube (SWNT) with three additional top-gates. At low\ntemperatures the system acts as a double quantum dot with large inter-dot\ntunnel coupling allowing for the observation of tunnel-coupled molecular states\nextending over the whole double-dot system. We precisely extract the tunnel\ncoupling and identify the molecular states by the sequential-tunneling line\nshape of the resonances in differential conductance."
    },
    {
        "anchor": "Electron and Hole Mobilities in Single-Layer WSe2: Single-layer transition metal dichalcogenide (TMD) WSe2 has recently\nattracted a lot of attention because it is a 2D semiconductor with a direct\nband-gap. Due to low doping levels it is intrinsic and shows ambipolar\ntransport. This opens up the possibility to realize devices with the Fermi\nlevel located in valence band, where the spin/valley coupling is strong and\nleads to new and interesting physics. As a consequence of its intrinsically low\ndoping, large Schottky barriers form between WSe2 and metal contacts, which\nimpede the injection of charges at low temperatures. Here, we report on the\nstudy of single-layer WSe2 transistors with a polymer electrolyte gate\n(PEO:LiClO4). Polymer electrolytes allow the charge carrier densities to be\nmodulated to very high values, allowing the observation of both the electron-\nand the hole-doped regimes. Moreover, our ohmic contacts formed at low\ntemperatures allow us to study the temperature dependence of electron and hole\nmobilities. At high electron densities, a re-entrant insulating regime is also\nobserved, a feature which is absent at high hole densities.",
        "positive": "Fluctuations in heat current and scaling dimension: In this work, we theoretically study the heat flow between two $1+1$d chiral\ngapless systems connected by a point contact. With a small temperature gradient\nbetween the two, we find that the ratio between fluctuations of the heat\ncurrent and the heat current itself is proportional to the scaling dimension --\na universal number that characterizes the distribution of the particles\ntunneling through the point contact. We adopt two different approaches,\nscattering theory and conformal field theory, to calculate this ratio and see\nthat their results agree. Our findings are useful for probing not only\nfractional charge excitations in fractional quantum Hall states but also\nneutral ones in non-Abelian phases."
    },
    {
        "anchor": "Rashba billiards: We study the energy levels of non-interacting electrons confined to move in\ntwo-dimensional billiard regions and having a spin-dependent dynamics due to a\nfinite Rashba spin splitting. The Green's function for such Rashba billiards is\nconstructed analytically and used to find the area and perimeter contributions\nto the density of states, as well as the smooth counting function. We show\nthat, in contrast to systems with spin-rotational invariance, Rashba billiards\nalways possess a negative energy spectrum. A semi-classical analysis is\npresented to interpret the singular behavior of the density of states at\ncertain negative energies. Our detailed analysis of the spin structure of\nRashba billiards reveals a finite out-of-plane spin projection for electron\neigenstates.",
        "positive": "Electrically-controllable RKKY interaction in semiconductor quantum\n  wires: We demonstrate in theory that it is possible to all-electrically manipulate\nthe RKKY interaction in a quasi-one-dimensional electron gas embedded in a\nsemiconductor heterostructure, in the presence of Rashba and Dresselhaus\nspin-orbit interaction. In an undoped semiconductor quantum wire where\nintermediate excitations are gapped, the interaction becomes the short-ranged\nBloembergen-Rowland super-exchange interaction. Owing to the interplay of\ndifferent types of spin-orbit interaction, the interaction can be controlled to\nrealize various spin models, e.g., isotropic and anisotropic Heisenberg-like\nmodels, Ising-like models with additional Dzyaloshinsky-Moriya terms, by tuning\nthe external electric field and designing the crystallographic directions. Such\ncontrollable interaction forms a basis for quantum computing with localized\nspins and quantum matters in spin lattices."
    },
    {
        "anchor": "Effect of Substitutional Impurities on the Electronic States and\n  Conductivity of Crystals with Half-filled Band: Low temperature quantum corrections to the density of states (DOS) and the\nconductivity are examined for a two-dimensional(2D) square crystal with\nsubstitutional impurities. By summing the leading logarithmic corrections to\nthe DOS its energy dependence near half-filling is obtained. It is shown that\nsubstitutional impurities do not suppress the van Hove singularity at the\nmiddle of the band, however they change its energy dependence strongly. Weak\ndisorder due to substitutional impurities in the three-dimensional simple cubic\nlattice results in a shallow dip in the center of the band. The calculation of\nquantum corrections to the conductivity of a 2D lattice shows that the\nwell-known logarithmic localization correction exists for all band fillings.\nFurthermore the magnitude of the correction increases as half-filling is\napproached. The evaluation of the obtained analytical results shows evidence\nfor delocalized states in the center of the band of a 2D lattice with\nsubstitutional impurities.",
        "positive": "The almost mobility edge in the almost Mathieu equation: Harper's equation (aka the \"almost Mathieu\" equation) famously describes the\nquantum dynamics of an electron on a one dimensional lattice in the presence of\nan incommensurate potential with magnitude $V$ and wave number $Q$. It has been\nproven that all states are delocalized if $V$ is less than a critical value\n$V_c=2t$ and localized if $V> V_c$. Here, we show that this result (while\ncorrect) is highly misleading, at least in the small $Q$ limit. In particular,\nfor $V<V_c$ there is an abrupt crossover akin to a mobility edge at an energy\n$E_c$; states with energy $|E|<E_c$ are robustly delocalized, but those in the\ntails of the density of states, with $|E|>E_c$, form a set of narrow bands with\nexponentially small bandwidths $ \\sim t\\ \\exp[-(2\\pi\\alpha/Q)]$ (where $\\alpha$\nis an energy dependent number of order 1) separated by band-gaps $ \\sim t Q$.\nThus, the states with $|E|> E_c$ are \"almost localized\" in that they have an\nexponentially large effective mass and are easily localized by small\nperturbations. We establish this both using exact numerical solution of the\nproblem, and by exploiting the well known fact that the same eigenvalue problem\narises in the Hofstadter problem of an electron moving on a 2D lattice in the\npresence of a magnetic field, $B=Q/2\\pi$. From the 2D perspective, the almost\nlocalized states are simply the Landau levels associated with semiclassical\nprecession around closed contours of constant quasiparticle energy; that they\nare not truly localized reflects an extremely subtle form of magnetic\nbreakdown."
    },
    {
        "anchor": "General scheme for stable single and multiatom nanomagnets according to\n  symmetry selection rules: At low temperature, information can be stored in the orientation of the\nlocalized magnetic moment of an adatom. However, scattering of electrons and\nphonons with the nanomagnet leads its state to have incoherent classical\ndynamics and might cause fast loss of the encoded information. Recently, it has\nbeen understood that such scattering obeys certain selection rules due to the\nsymmetries of the system. By analyzing the point-group symmetry of the surface,\nthe time-reversal symmetry and the magnitude of the adatom effective spin, we\nidentify which nanomagnets configurations are to be avoided and which are\npromising to encode a stable bit. A new tool of investigation is introduced and\nexploited: the quasi-spin quantum number. By means of this tool, our results\nare easily generalized to a broad class of bipartite cluster configurations\nwhere adatoms are coupled through Heisenberg-like interactions. Finally, to\nmake contact with the experiments, numerical simulations have been performed to\nshow how such stable configurations respond to typical scanning tunneling\nmicroscopy measurements.",
        "positive": "Quasiparticle energy bands and Fermi surfaces of monolayer NbSe$_2$: A quasiparticle band structure of a single layer 2H-NbSe$_2$ is reported by\nusing first-principles $GW$ calculation. We show that a self-energy correction\nincreases the width of a partially occupied band and alters its Fermi surface\nshape when comparing those using conventional mean-field calculation methods.\nOwing to a broken inversion symmetry in the trigonal prismatic single layer\nstructure, the spin-orbit interaction is included and its impact on the Fermi\nsurface and quasiparticle energy bands are discussed. We also calculate the\ndoping dependent static susceptibilities from the band structures obtained by\nthe mean-field calculation as well as $GW$ calculation with and without\nspin-orbit interactions. A complete tight-binding model is constructed within\nthe three-band third nearest neighbour hoppings and is shown to reproduce our\n$GW$ quasiparticle energy bands and Fermi surface very well. Considering\nvariations of the Fermi surface shapes depending on self-energy corrections and\nspin-orbit interactions, we discuss the formations of charge density wave (CDW)\nwith different dielectric environments and their implications on recent\ncontroversial experimental results on CDW transition temperatures."
    },
    {
        "anchor": "Noncollinear Antiferromagnetic Spintronics: Antiferromagnetic spintronics is one of the leading candidates for\nnext-generation electronics. Among abundant antiferromagnets, noncollinear\nantiferromagnets are promising for achieving practical applications due to\ncoexisting ferromagnetic and antiferromagnetic merits. In this perspective, we\nbriefly review the recent progress in the emerging noncollinear\nantiferromagnetic spintronics from fundamental physics to device applications.\nCurrent challenges and future research directions for this field are also\ndiscussed.",
        "positive": "Local density of states in disordered two-dimensional electron gases at\n  high magnetic field: Motivated by high-accuracy scanning tunneling spectroscopy measurements on\ndisordered two-dimensional electron gases in strong magnetic field, we present\nan exact solution for the local density of states (LDoS) of electrons moving in\nan arbitrary potential smooth on the scale of the magnetic length, that can be\nlocally described up to its second derivatives. We use a technique based on\ncoherent state Green's functions, allowing us to treat on an equal footing\nconfining and open quantum systems. The energy-dependence of the LDoS is found\nto be universal in terms of local geometric properties, such as drift velocity\nand potential curvature. We also show that thermal effects are quite important\nclose to saddle points, leading to an overbroadening of the tunneling\ntrajectories."
    },
    {
        "anchor": "Shot noise and transport in small quantum cavities with large openings: We present a dynamical analysis of the transport through small quantum\ncavities with large openings. The systematic suppression of shot noise is used\nto distinguish direct, deterministic from indirect, indeterministic transport\nprocesses. The analysis is based on quantum mechanical calculations of $S$\nmatrices and their poles for quantum billiards with convex boundaries of\ndifferent shape and two open channels in each of the two attached leads. Direct\nprocesses are supported when special states couple strongly to the leads, and\ncan result in deterministic transport as signified by a striking\nsystem-specific suppression of shot noise.",
        "positive": "Spin-torque shot noise in magnetic tunnel junctions: Spin polarized current may transfer angular momentum to a ferromagnet,\nresulting in a spin-torque phenomenon. At the same time the shot noise,\nassociated with the current, leads to a non-equilibrium stochastic force acting\non the ferromagnet. We derive stochastic version of Landau-Lifshitz-Gilbert\nequation for a magnetization of a ''free'' ferromagnetic layer in contact with\na ''fixed'' ferromagnet. We solve the corresponding Fokker-Planck equation and\nshow that the non-equilibrium noise yields to a non-monotonous dependence of\nthe precession spectrum linewidth on the current."
    },
    {
        "anchor": "Domain walls in gapped graphene: The electronic properties of a particular class of domain walls in gapped\ngraphene are investigated. We show that they can support mid-gap states which\nare localized in the vicinity of the domain wall and propagate along its\nlength. With a finite density of domain walls, these states can alter the\nelectronic properties of gapped graphene significantly. If the mid-gap band is\npartially filled,the domain wall can behave like a one-dimensional metal\nembedded in a semi-conductor, and could potentially be used as a single-channel\nquantum wire.",
        "positive": "Hydrodynamic magnetotransport in two-dimensional electron systems with\n  macroscopic obstacles: In high-quality conductors, the hydrodynamic regime of electron transport has\nbeen recently realized. In this work we theoretically investigate\nmagnetotransport of a viscous electron fluid in samples with\nelectron-impermeable obstacles. We use the two approaches to describe the fluid\nflow. The first one is based on the equations of hydrodynamics of a charged\nfluid, which assume that the kinetic equation takes into account the two\nharmonics of the electron distribution function. The second approach is based\non the equations that are obtained by taking into account three harmonics of\nthe distribution function (''quasi-hydrodynamics''). Within the hydrodynamic\napproach, we consider the cases of the rough and the smooth edges of the disks,\non which the electron scattering is diffusive or specular, respectively. The\nlongitudinal magnetoresistivity turns out to be strong and negative, the same\nfor both rough and smooth discs edges to within small corrections. For rough\ndiscs, the Hall resistivity is equal to its standard value. For smooth discs\nthe Hall resistance acquire a small correction to the standard value,\nproportional to the Hall viscosity. In the quasi-hydrodynamic approach, we\nconsidered the case of smooth discs and small magnetic fields. In the regime\nwhen the flow is substantially different from the hydrodynamic one, the\nlongitudinal resistivity does not depend on the shear stress relaxation time\n(but depends on the relaxation time of the third angular harmonic), while the\ncorrection to the standard Hall resistivity does not depend on both relaxation\ntimes. We compare the results of the hydrodynamic calculation of the\nlongitudinal resistance with the experimental data on magnetotransport in\nhigh-quality GaAs quantum wells with macroscopic defects. A good agreement of\ntheory and experiment evidences in favor of the realization of the hydrodynamic\ntransport regime in such systems."
    },
    {
        "anchor": "Non Equilibrium Noise as a Probe of the Kondo Effect in Mesoscopic Wires: We study the non-equilibrium noise in mesoscopic diffusive wires hosting\nmagnetic impurities. We find that the shot-noise to current ratio develops a\npeak at intermediate source-drain biases of the order of the Kondo temperature.\nThe enhanced impurity contribution at intermediate biases is also manifested in\nthe effective distribution. The predicted peak represents increased inelastic\nscattering rate at the non-equilibrium Kondo crossover.",
        "positive": "Universal model for electron thermal-field emission from two-dimensional\n  semimetals: We present the theory of out-of-plane (or vertical) electron thermal-field\nemission from 2D semimetals. We show that the current-voltage-temperature\ncharacteristic is well-captured by a universal scaling relation applicable for\nbroad classes of 2D semimetals, including graphene and its few-layer, nodal\npoint semimetal, Dirac semimetal at the verge of topological phase transition\nand nodal line semimetal. Here an important consequence of the universal\nemission behavior is revealed: in contrast to the common expectation that band\ntopology shall manifest differently in the physical observables, band\ntopologies in two spatial dimension are indistinguishable from each others and\nbear no special signature in the electron emission characteristics. Our\nfindings represent the quantum extension of the universal semiclassical\nthermionic emission scaling law in 2D materials, and provide the theoretical\nfoundations for the understanding of electron emission from cathode and charge\ninterface transport for the design of 2D-material-based vacuum nanoelectronics."
    },
    {
        "anchor": "The stability of the fractional quantum Hall effect in topological\n  insulators: With the recent observation of graphene-like Landau levels at the surface of\ntopological insulators, the possibility of fractional quantum Hall effect,\nwhich is a fundamental signature of strong correlations, has become of\ninterest. Some experiments have reported intra-Landau level structure that is\nsuggestive of fractional quantum Hall effect. This paper discusses the\nfeasibility of fractional quantum Hall effect from a theoretical perspective,\nand argues that while this effect should occur, ideally, in the $n=0$ and\n$|n|=1$ Landau levels, it is ruled out in higher $|n|$ Landau levels. Unlike\ngraphene, the fractional quantum Hall effect in topological insulators is\npredicted to show an interesting asymmetry between $n=1$ and $n=-1$ Landau\nlevels due to spin-orbit coupling.",
        "positive": "Characterization of Qubit Dephasing by Landau-Zener Interferometry: Controlling coherent interaction at avoided crossings is at the heart of\nquantum information processing. The regime between sudden switches and\nadiabatic transitions is characterized by quantum superpositions that enable\ninterference experiments. Here, we implement periodic passages at intermediate\nspeed in a GaAs-based two-electron charge qubit and observe\nLandau-Zener-St\\\"uckelberg-Majorana (LZSM) quantum interference of the\nresulting superposition state. We demonstrate that LZSM interferometry is a\nviable and very general tool to not only study qubit properties but beyond to\ndecipher decoherence caused by complex environmental influences. Our scheme is\nbased on straightforward steady state experiments. The coherence time of our\ntwo-electron charge qubit is limited by electron-phonon interaction. It is much\nlonger than previously reported for similar structures."
    },
    {
        "anchor": "Radiative and Non-Radiative Exciton Energy Transfer in Monolayers of\n  Two-Dimensional Transition Metal Dichalcogenides: We present results on the rates of interlayer energy transfer between\nexcitons in two-dimensional transition metal dichalcogenides (TMDs). We\nconsider both radiative (mediated by real photons) and non-radiative (mediated\nby virtual photons) mechanisms of energy transfer using a unified Green's\nfunction approach that takes into account modification of the exciton energy\ndispersions as a result of interactions. The large optical oscillator strengths\nassociated with excitons in TMDs result in very fast energy transfer rates. The\nenergy transfer times depend on the exciton momentum, exciton linewidth, and\nthe interlayer separation and can range from values less than 100 femtoseconds\nto more than tens of picoseconds. Whereas inside the light cone the energy\ntransfer rates of longitudinal and transverse excitons are comparable, outside\nthe light cone the energy transfer rates of longitudinal excitons far exceed\nthose of transverse excitons. Average energy transfer times for a thermal\nensemble of longitudinal and transverse excitons is temperature dependent and\ncan be smaller than a picosecond at room temperature for interlayer separations\nsmaller than 10 nm. Energy transfer times of localized excitons range from\nvalues less than a picosecond to several tens of picoseconds. When the exciton\nscattering and dephasing rates are small, energy transfer dynamics exhibit\ncoherent oscillations. Our results show that electromagnetic interlayer energy\ntransfer can be an efficient mechanism for energy exchange between TMD\nmonolayers.",
        "positive": "Incomplete Andreev reflection in a clean\n  Superconductor/Ferromagnet/Superconductor junction: We study the Josephson effect in a clean\nSuperconductor-Ferromagnet-Superconductor junction for arbitrarily large spin\npolarizations. The Andreev reflection at a clean Ferromagnet-Superconductor\ninterface is incomplete, and Andreev channels with a large incidence angle are\nprogressively suppressed with increasing exchange energy. As a result, the\ncritical current exhibits oscillations as a function of the exchange energy and\nof the length of the ferromagnet and has a temperature dependence which\ndeviates from the one predicted by the quasiclassical theory."
    },
    {
        "anchor": "Defect mediated melting and the breaking of quantum double symmetries: In this paper, we apply the method of breaking quantum double symmetries to\nsome cases of defect mediated melting. The formalism allows for a systematic\nclassification of possible defect condensates and the subsequent confinement\nand/or liberation of other degrees of freedom. We also show that the breaking\nof a double symmetry may well involve a (partial) restoration of an original\nsymmetry. A detailed analysis of a number of simple but representative examples\nis given, where we focus on systems with global internal and external (space)\nsymmetries. We start by rephrasing some of the well known cases involving an\nAbelian defect condensate, such as the Kosterlitz-Thouless transition and\none-dimensional melting, in our language. Then we proceed to the non-Abelian\ncase of a hexagonal crystal, where the hexatic phase is realized if\ntranslational defects condense in a particular rotationally invariant state.\nOther conceivable phases are also described in our framework.",
        "positive": "Block-determinant formalism for an action of a multi-terminal scatterer: The scattering theory of electron transport allows for a compact and powerful\ndescription in terms of $\\check{g}^2 = 1$ Green functions, so-called circuit\ntheory of quantum transport. A scatterer in the theory is characterized by an\naction, most generally a Keldysh one, that can be further used as a building\nbock of theories describing statistics of electron transport, superconducting\ncorrelations, time-dependent and interaction effects. The action is usually\nused in the form suitable for a two-terminal scatterer.\n  Here we provide a comprehensive derivation of a more general form of the\naction that is especially suitable and convenient for general multi-terminal\nscatterers. The action is expressed as a determinant of a block of the\nscattering matrix obtained by projection on the positive eigenvalues of the\nGreen functions characterizing the reservoirs. We start with traditional Green\nfunction formalism introducing $\\check{g}^2 = 1$ matrices and give a first\nexample of multi-terminal counting statistics. Further we consider\none-dimensional channels and discuss chiral anomaly arising in this context.\nGeneralizing on many channels and superconducting situation, we arrive at the\nblock-determinant relation. We give the necessary elaborative examples\nreproducing basic results of counting statistics and super-currents in\nmulti-terminal junctions."
    },
    {
        "anchor": "Engineering interband tunneling in nanowires with diamond cubic or\n  zincblende crystalline structure based on atomistic modeling: We present an investigation in the device parameter space of band-to-band\ntunneling in nanowires with a diamond cubic or zincblende crystalline\nstructure. Results are obtained from quantum transport simulations based on\nNon-Equilibrium Green's functions with a tight-binding atomistic Hamiltonian.\nInterband tunneling is extremely sensitive to the longitudinal electric field,\nto the nanowire cross section, through the gap, and to the material. We have\nderived an approximate analytical expression for the transmission probability\nbased on WKB theory and on a proper choice of the effective interband tunneling\nmass, which shows good agreement with results from atomistic quantum\nsimulation.",
        "positive": "Parasitic pumping currents in an interacting quantum dot: We analyze the charge and spin pumping in an interacting dot within the\nalmost adiabatic limit. By using a non-equilibrium Green's function technique\nwithin the time-dependent slave boson approximation, we analyze the pumped\ncurrent in terms of the dynamical constraints in the infinite-U regime. The\nresults show the presence of parasitic pumping currents due to the additional\nphases of the constraints. The behavior of the pumped current through the\nquantum dot is illustrated in the spin-insensitive and in the spin-sensitive\ncase relevant for spintronics applications."
    },
    {
        "anchor": "Model $I$--$V$ curves and figures of merit of underdamped deterministic\n  Josephson ratchets: We propose simple models for the current-voltage characteristics of typical\nJosephson ratchets. We consider the case of a ratchet working against a\nconstant applied counter force and derive analytical expressions for the key\ncharacteristics of such a ratchet: rectification curve, stopping force, input\nand output powers and rectification efficiency. Optimization of the ratchet\nperformance is discussed.",
        "positive": "An Illumination- and Temperature-Dependent Analytical Model for Copper\n  Indium Gallium Diselenide (CIGS) Solar Cells: In this paper, we present a physics-based analytical model for CIGS solar\ncells that describes the illumination- and temperature-dependent\ncurrent-voltage (I-V) characteristics and accounts for the statistical shunt\nvariation of each cell. The model is derived by solving the drift-diffusion\ntransport equation so that its parameters are physical, and, therefore, can be\nobtained from independent characterization experiments. The model is validated\nagainst CIGS I-V characteristics as a function of temperature and illumination\nintensity. This physics-based model can be integrated into a large-scale\nsimulation framework to optimize the performance of solar modules as well as\npredict the long-term output yields of photovoltaic farms under different\nenvironmental conditions."
    },
    {
        "anchor": "Nonlinear magnetization dynamics driven by strong terahertz fields: We present a comprehensive experimental and numerical study of magnetization\ndynamics triggered in a thin metallic film by single-cycle terahertz pulses of\n$\\sim20$ MV/m electric field amplitude and $\\sim1$ ps duration. The\nexperimental dynamics is probed using the femtosecond magneto-optical Kerr\neffect (MOKE), and it is reproduced numerically using macrospin simulations.\nThe magnetization dynamics can be decomposed in three distinct processes: a\ncoherent precession of the magnetization around the terahertz magnetic field,\nan ultrafast demagnetization that suddenly changes the anisotropy of the film,\nand a uniform precession around the equilibrium effective field that is relaxed\non the nanosecond time scale, consistent with a Gilbert damping process.\nMacrospin simulations quantitatively reproduce the observed dynamics, and allow\nus to predict that novel nonlinear magnetization dynamics regimes can be\nattained with existing table-top terahertz sources.",
        "positive": "Quantum criticality near the Stoner transition in a two-dot with\n  spin-orbit coupling: We study a system of two tunnel-coupled quantum dots, with the first dot\ncontaining interacting electrons (described by the Universal Hamiltonian) not\nsubject to spin-orbit coupling, whereas the second contains non-interacting\nelectrons subject to spin-orbit coupling. We focus on describing the behavior\nof the system near the Stoner transition. Close to the critical point quantum\nfluctuations become important and the system enters a quantum critical regime.\nThe large-$N$ approximation allows us to calculate physical quantitites\nreliably even in this strongly fluctuating regime. In particular, we find a\nscaling function to describe the crossover of the quasiparticle decay rate\nbetween the renormalized Fermi liquid regime and the quantum critical regime."
    },
    {
        "anchor": "Large magneto-optical effects and magnetic anisotropy energy in\n  two-dimensional Cr$_2$Ge$_2$Te$_6$: By performing systematic $ab$ $initio$ density functional calculations, here\nwe study two relativity-induced properties of atomically thin ferromagnetic\n(FM) Cr$_2$Ge$_2$Te$_6$ films [monolayer (ML), bilayer (BL) and trilayer (TL)\nas well as bulk], namely, magnetic anisotropy energy (MAE) and magneto-optical\n(MO) effects. Competing contributions of both magneto-crystalline anisotropy\nenergy (C-MAE) and magnetic dipolar anisotropy energy (D-MAE) to the MAE, are\ncomputed. Calculated MAEs of these materials are large, being in the order of\n$\\sim$0.1 meV/Cr. Interestingly, we find that the out-of-plane magnetic\nanisotropy is preferred in all the systems except the ML where an in-plane\nmagnetization is favored because here the D-MAE is larger than the C-MAE.\nCrucially, this explains why long-range FM order was observed in all the\nfew-layer Cr$_2$Ge$_2$Te$_6$ except the ML because the out-of-plane magnetic\nanisotropy would open a spin-wave gap and thus suppress magnetic fluctuations\nso that long-range FM order could be stabilized at finite temperature. In the\nvisible frequency range, large Kerr rotations up to $\\sim$1.0 deg in these\nmaterials are predicted and they are comparable to that observed in famous MO\nmaterials such as PtMnSb and Y$_3$Fe$_5$O$_{12}$. Moreover, they are $\\sim$100\ntimes larger than that of 3$d$ transition metal MLs deposited on Au surfaces.\nFaraday rotation angles in these 2D materials are also large, being up to\n$\\sim$120 deg/$\\mu$m, and are thus comparable to the best-known MO\nsemiconductor Bi$_3$Fe$_5$O$_{12}$. These findings thus suggest that with large\nMAE and MO effects, atomically thin Cr$_2$Ge$_2$Te$_6$ films would have\npotential applications in novel magnetic, MO and spintronic nanodevices.",
        "positive": "Universal Hall conductance scaling in non-Hermitian Chern insulators: We investigate the Hall conductance of a two-dimensional Chern insulator\ncoupled to an environment causing gain and loss. Introducing a biorthogonal\nlinear response theory, we show that sufficiently strong gain and loss lead to\na characteristic non-analytical contribution to the Hall conductance. Near its\nonset, this contribution exhibits a universal power-law with a power 3/2 as a\nfunction of Dirac mass, chemical potential and gain strength. Our results pave\nthe way for the study of non-Hermitian topology in electronic transport\nexperiments."
    },
    {
        "anchor": "Giant dynamical Zeeman split in inverse spin valves: The inversion of a spin valve device is proposed. Opposite to a conventional\nspin valve of a non-magnetic spacer sandwiched between two ferromagnetic\nmetals, an inverse spin valve is a ferromagnet sandwiched between two\nnon-magnetic metals. It is predicted that, under a bias, the chemical\npotentials of spin-up and spin-down electrons in the metals split at\nmetal-ferromagnet interfaces, a dynamical Zeeman effect. This split is of the\norder of an applied bias. Thus, there should be no problem of generating an\n$eV$ split that is not possible to be realized on the earth by the usual Zeeman\neffect.",
        "positive": "Electronic Manipulation of Magnon Topology by Chirality Injection from\n  Boundaries: Magnon bands are known to exhibit nontrivial topology in ordered magnets\nunder suitable conditions, engendering topological phases referred to as\nmagnonic topological insulators. Conventional methods to drive a magnonic\ntopological phase transition are bulk magnetic or thermal operations such as\nchanging the direction of an external magnetic field or varying the temperature\nof the system, which are undesired in device applications of magnon topology.\nIn this work, we lift the limitation of the magnon topology control on the bulk\nnon-electronic manipulation by proposing a scheme to manipulate magnonic\ntopological phases by electronic boundary operations of spin chirality\ninjection. More specifically, we consider a ferromagnetic honeycomb lattice and\nshow that a finite spin chirality injected from the boundary of the system via\nthe spin Hall effects introduces a tunable sublattice-symmetry-breaking mass\nterm to the bosonic counterpart of the Haldane model for the Chern insulators\nand thereby allows us to electronically manipulate the bulk topology of magnons\nfrom the boundary. The \"shoulder\" in the thermal Hall conductivity profile is\nproposed as an experimental probe of the chirality-induced topological phase\ntransition. The scheme for the boundary manipulation of the magnon topology is\nshown to work for a honeycomb antiferromagnet as well. We envisage that the\ninterfacial chirality injection may offer a nonintrusive electronic means to\ntune the static and the dynamical bulk properties of general magnetic systems."
    },
    {
        "anchor": "Magneto-optics of massive Dirac fermions in bulk Bi2Se3: We report on magneto-optical studies of Bi2Se3, a representative member of\nthe 3D topological insulator family. Its electronic states in bulk are shown to\nbe well described by a simple Dirac-type Hamiltonian for massive particles with\nonly two parameters: the fundamental bandgap and the band velocity. In a\nmagnetic field, this model implies a unique property - spin splitting equal to\ntwice the cyclotron energy: Es = 2Ec. This explains the extensive\nmagneto-transport studies concluding a fortuitous degeneracy of the spin and\norbital split Landau levels in this material. The Es = 2Ec match differentiates\nthe massive Dirac electrons in bulk Bi2Se3 from those in quantum\nelectrodynamics, for which Es = Ec always holds.",
        "positive": "Accuracy of a mechanical single electron shuttle: Motivated by recent experiments, we calculate both the average current and\nthe current fluctuations for a metallic island which oscillates between two\nsymmetric electrodes. Electrons can only tunnel on or off the island when it is\nclose to one of the electrodes. Using a Master equation we investigate the\naccuracy of such an electron shuttle both analytically and numerically. It is\nshown that optimum operation is reached when the contact time is much larger\nthan the RC-time."
    },
    {
        "anchor": "Higher-order topological corner states induced solely by onsite\n  potentials with mirror symmetry: Higher-order topological insulators have triggered great interests because of\nexhibitions of non-trivial bulk topology on lower-dimensional boundaries like\ncorners and hinges. While such interesting phases have been investigated in a\nplethora of systems by tuning staggered tunneling strength or manipulating\nexisting topological phases, here we show that a higher-order topological phase\ncan be driven solely by mirror-symmetric onsite potentials. We first introduce\na simple chain model in one dimension that mimics the Su-Schrieffer-Heeger-like\nmodel. However, due to the lack of internal symmetries like chiral or\nparticle-hole symmetry, the energies of the topological edge modes are not\npinned at zero. Once the model is generalized to two dimensions, we observe the\nemergence of topological corner modes. These corner modes are intrinsic\nmanifestation of non-trivial bulk band topology protected by mirror symmetry,\nand thus, they are robust against symmetry-preserved perturbations. Our study\nprovides a concise proposal for realizing a class of higher-order topological\ninsulators, which involves only tuning onsite energies. This can be easily\naccessible in experiments and provides a different playground for engineering\ntopological corner modes.",
        "positive": "Umklapp-Assisted Electron Transport Oscillations in Metal Superlattices: We consider a superlattice of parallel metal tunnel junctions with a\nspatially non-homogeneous probability for electrons to tunnel. In such\nstructures tunneling can be accompanied by electron scattering that conserves\nenergy but not momentum. In the special case of a tunneling probability that\nvaries periodically with period $a$ in the longitudinal direction, i.e.,\nperpendicular to the junctions, electron tunneling is accompanied by \"umklapp\"\nscattering, where the longitudinal momentum changes by a multiple of $h/a$. We\npredict that as a result a sequence of metal-insulator transitions can be\ninduced by an external electric- or magnetic field as the field strength is\nincreased."
    },
    {
        "anchor": "Mapping electron delocalization by charge transport spectroscopy in an\n  artificial molecule: In this letter we present an experimental realization of the quantum\nmechanics textbook example of two interacting electronic quantum states that\nhybridize forming a molecular state. In our particular realization, the quantum\nstates themselves are fabricated as quantum dots in a molecule, a carbon\nnanotube.\n  For sufficient quantum-mechanical interaction (tunnel coupling) between the\ntwo quantum states, the molecular wavefunction is a superposition of the two\nisolated (dot) wavefunctions. As a result, the electron becomes delocalized and\na covalent bond forms.\n  In this work, we show that electrical transport can be used as a sensitive\nprobe to measure the relative weight of the two components in the superposition\nstate as a function of the gate-voltages.\n  For the field of carbon nanotube double quantum dots, the findings represent\nan additional step towards the engineering of quantum states.",
        "positive": "Magnetic-field effects on photon-induced quantum transport in a single\n  dot-cavity system: In this study, we show how a static magnetic field can control photon-induced\nelectron transport through a quantum dot system coupled to a photon cavity. The\nquantum dot system is connected to two electron reservoirs and exposed to an\nexternal perpendicular static magnetic field. The propagation of electrons\nthrough the system is thus influenced by the static magnetic and the dynamic\nphoton fields. It is observed that the photon cavity forms photon replica\nstates controlling electron transport in the system. IF the photon field has\nmore energy than the cyclotron energy, then the photon field is dominant in the\nelectron transport. Consequently, the electron transport is enhanced due to\nactivation of photon replica states. By contrast, the electron transport is\nsuppressed in the system when the photon energy is smaller than the cyclotron\nenergy."
    },
    {
        "anchor": "Microscopic origin of the bolometric effect in graphene: While the thermoelectric and photoconduction effects are crucial in pristine\nand low-doped graphene, the bolometric effect is known to dominate the\nphotoresponse in biased graphene. Here, we present a detailed microscopic\ninvestigation of the photoresponse due to the bolometric effect in graphene.\nBased on the semiconductor Bloch equations, we investigate the time- and\nmomentumresolved carrier dynamics in graphene in the presence of a constant\nelectric field under optical excitation. The magnitude of the bolometric effect\nis determined by the optically induced increase of temperature times the\nconductivity change. Investigating both factors independently, we reveal that\nthe importance of the bolometric effect in the high-doping regime can be mostly\nascribed to the latter showing a parabolic dependence on the doping.",
        "positive": "Effects of the field modulation on the Hofstadter's spectrum: We study the effect of spatially modulated magnetic fields on the energy\nspectrum of a two-dimensional (2D) Bloch electron. Taking into account four\nkinds of modulated fields and using the method of direct diagonalization of the\nHamiltonian matrix, we calculate energy spectra with varying system parameters\n(i.e., the kind of the modulation, the relative strength of the modulated field\nto the uniform background field, and the period of the modulation) to elucidate\nthat the energy band structure sensitively depends on such parameters:\nInclusion of spatially modulated fields into a uniform field leads occurrence\nof gap opening, gap closing, band crossing, and band broadening, resulting\ndistinctive energy band structure from the Hofstadter's spectrum. We also\ndiscuss the effect of the field modulation on the symmetries appeared in the\nHofstadter's spectrum in detail."
    },
    {
        "anchor": "Experimental evidence for electron-electron interaction and spin-charge\n  separation in graphene quantum dots: Graphene quantum dots (GQDs) can exhibit a range of spectacular phenomena\nsuch as the Klein-tunneling-induced quasibound states1-6 and Berry-phase-tuned\nenergy spectra7-15. According to previous studies, all these interesting\nquantum phenomena seem to be well understood in the free electron picture1-15.\nHowever, electronic motion in the GQDs is reduced to quantized orbits by\nquantum confinement, which implies that the kinetic energy may be comparable to\nor even smaller than the Coulomb energy of the quasiparticles, possibly\nresulting in exotic correlated phases in the GQDs. Here we present a scanning\ntunneling microscopy and spectroscopy study of gate-tunable GQDs in\ngraphene/WSe2 heterostructure devices and report for the first time the\nobservation of electron-electron interaction and correlation-induced\nspin-charge separation in the GQDs. Gating allows us to precise characterize\neffects of the electron-electron interaction on the energy spectra of the GQDs.\nBy measuring density of states as a function of energy and position, we\nexplicitly uncover two density waves with different velocities in the GQDs,\nattributing to spin-charge separation in real space.",
        "positive": "Non-Hermitian route to higher-order topology in an acoustic crystal: Topological phases of matter are classified based on their Hermitian\nHamiltonians, whose real-valued dispersions together with orthogonal\neigenstates form nontrivial topology. In the recently discovered higher-order\ntopological insulators (TIs), the bulk topology can even exhibit hierarchical\nfeatures, leading to topological corner states, as demonstrated in many\nphotonic and acoustic artificial materials. Naturally, the intrinsic loss in\nthese artificial materials has been omitted in the topology definition, due to\nits non-Hermitian nature; in practice, the presence of loss is generally\nconsidered harmful to the topological corner states. Here, we report the\nexperimental realization of a higher-order TI in an acoustic crystal, whose\nnontrivial topology is induced by deliberately introduced losses. With local\nacoustic measurements, we identify a topological bulk bandgap that is populated\nwith gapped edge states and in-gap corner states, as the hallmark signatures of\nhierarchical higher-order topology. Our work establishes the non-Hermitian\nroute to higher-order topology, and paves the way to exploring various exotic\nnon-Hermiticity-induced topological phases."
    },
    {
        "anchor": "Superconducting transition edge sensors with phononic thermal isolation: The sensitivity of a low-noise superconducting transition edge sensor (TES)\nis determined by the thermal conductance of the support structure that connects\nthe active elements of the device to the heat bath. Low-noise devices require\nconductances in the range 0.1 to 10 pWK$^{-1}$, and so have to rely on\ndiffusive phonon scattering in long, narrow, amorphous SiN$_\\text{x}$ legs. We\nshow that it is possible to manufacture and operate TESs having short,\nballistic low-dimensional legs (cross section 500$\\times$200 nm) that contain\nmulti-element phononic interferometers and ring resonators. These legs\ntransport heat in effectively just 5 elastic modes at the TES's operating\ntemperature (< 150 mK), which is close to the quantised limit of 4. The\nphononic filters then reduce the thermal flux further by frequency-domain\nfiltering. For example, a micromachined 3-element ring resonator reduced the\nflux to 19 % of a straight-legged ballistic device operating at the quantised\nlimit, and 38 % of a straight-legged diffusive reference device. This work\nopens the way to manufacturing TESs where performance is determined entirely by\nfiltered, few-mode, ballistic thermal transport in short, low-heat capacity\nlegs, free from the artifacts of two level systems.",
        "positive": "Conductance of Pd-H nanojunctions: Results of an experimental study of palladium nanojunctions in hydrogen\nenvironment are presented. Two new hydrogen-related atomic configurations are\nfound, which have a conductances of ~0.5 and ~1 quantum unit (2e^2/h). Phonon\nspectrum measurements demonstrate that these configurations are situated\nbetween electrodes containing dissolved hydrogen. The crucial differences\ncompared to the previously studied Pt-H_2 junctions, and the possible\nmicroscopic realizations of the new configurations in palladium-hydrogen\natomic-sized contacts are discussed."
    },
    {
        "anchor": "Amplitude-dependent topological edge states in nonlinear phononic\n  lattices: This work investigates the effect of nonlinearities on topologically\nprotected edge states in one and two-dimensional phononic lattices. We first\nshow that localized modes arise at the interface between two spring-mass chains\nthat are inverted copies of each other. Explicit expressions derived for the\nfrequencies of the localized modes guide the study of the effect of cubic\nnonlinearities on the resonant characteristics of the interface which are shown\nto be described by a Duffing-like equation. Nonlinearities produce\namplitude-dependent frequency shifts, which in the case of a softening\nnonlinearity cause the localized mode to migrate to the bulk spectrum. The case\nof a hexagonal lattice implementing a phononic analogue of a crystal exhibiting\nthe quantum spin Hall effect is also investigated in the presence of weakly\nnonlinear cubic springs. An asymptotic analysis provides estimates of the\namplitude dependence of the localized modes, while numerical simulations\nillustrate how the lattice response transitions from bulk-to-edge\nmode-dominated by varying the excitation amplitude. In contrast with the\ninterface mode of the first example studies, this occurs both for hardening and\nsoftening springs. The results of this study provide a theoretical framework\nfor the investigation of nonlinear effects that induce and control\ntopologically protected wave-modes through nonlinear interactions and amplitude\ntuning.",
        "positive": "Disorder and interactions in quantum Hall ferromagnets: effects of\n  disorder in Skyrmion physics: We present a Hartree-Fock study of the competition between disorder and\ninteractions in quantum Hall ferromagnets near $\\nu=1$. We find that the ground\nstate at $\\nu=1$ evolves with increasing interaction strength from a\nquasi-metallic paramagnet, to a partially spin-polarized ferromagnetic Anderson\ninsulator, and to a fully spin-polarized ferromagnet with a charge gap. Away\nfrom $\\nu=1$, the ground state evolves from a conventional Anderson insulator,\nto a conventional quasiparticle glass, and finally to a ferromagnetic Skyrmion\nquasiparticle glass. These different regimes can be measured in low-temperature\ntransport and NMR experiments. We present calculations for the NMR spectra in\ndifferent disorder regimes."
    },
    {
        "anchor": "Optical detection of anyons in an integer quantum Hall system: Further experiments showed the incorrectness of proposed interpretation. We\nhave studied an in-plane resonant photo-response of an integer quantum Hall\nsystem in which time-reversal and parity symmetries are broken. The response of\ninitially homogeneous system exhibits a complicate spatial structure sensitive\nto the system macroscopic sizes. Conceptually, the effect is explained by the\nlarge-scale quantum entanglement originated from an indistinguishable particle\nstatistics. The concept is supported by the demonstration of\nentanglement-related transfer of information in the system interior.",
        "positive": "Circuit realisation of a two-orbital non-Hermitian tight-binding chain: We examine a non-Hermitian (NH) tight-binding system comprising of two\norbitals per unit cell and their electrical circuit analogues. We distinguish\nthe PT-symmetric and non-PT symmetric cases characterised by non-reciprocal\nnearest neighbour couplings and onsite gain/loss terms, respectively. The\nlocalisation of the edge modes or the emergence of the topological properties\nare determined via the maximum inverse participation ratio, which has distinct\ndependencies on the parameters that define the Hamiltonian. None of the above\nscenarios exhibits the non-Hermitian skin effect. We investigate the boundary\nmodes corresponding to the topological phases in a suitably designed electrical\ncircuit by analyzing the two-port impedance and retrieve the admittance band\nstructure of the circuit via imposing periodic boundary conditions. The\nobtained results are benchmarked against the Hermitian version of the\ntwo-orbital model to compare and discriminate against those obtained for the NH\nvariants."
    },
    {
        "anchor": "Transport theory for femtosecond laser-induced spin-transfer torques: Ultrafast demagnetization of magnetic layers pumped by a femtosecond laser\npulse is accompanied by a nonthermal spin-polarized current of hot electrons.\nThese spin currents are studied here theoretically in a spin valve with\nnoncollinear magnetizations. To this end, we introduce an extended model of\nsuperdiffusive spin transport that enables to treat noncollinear magnetic\nconfigurations, and apply it to the perpendicular spin valve geometry. We show\nhow spin-transfer torques arise due to this mechanism and calculate their\naction on the magnetization present, as well as how the latter depends on the\nthicknesses of the layers and other transport parameters. We demonstrate that\nthere exists a certain optimum thickness of the out-of-plane magnetized\nspin-current polarizer such that the torque acting on the second magnetic layer\nis maximal. Moreover, we study the magnetization dynamics excited by the\nsuperdiffusive spin-transfer torque due to the flow of hot electrons employing\nthe Landau-Lifshitz-Gilbert equation. Thereby we show that a femtosecond laser\npulse applied to one magnetic layer can excite small-angle precessions of the\nmagnetization in the second magnetic layer. We compare our calculations with\nrecent experimental results.",
        "positive": "Driving current through single organic molecules: We investigate electronic transport through two types of conjugated\nmolecules. Mechanically controlled break-junctions are used to couple thiol\nendgroups of single molecules to two gold electrodes. Current-voltage\ncharacteristics (IVs) of the metal-molecule-metal system are observed. These\nIVs reproduce the spatial symmetry of the molecules with respect to the\ndirection of current flow. We hereby unambigously detect an intrinsic property\nof the molecule, and are able to distinguish the influence of both the molecule\nand the contact to the metal electrodes on the transport properties of the\ncompound system."
    },
    {
        "anchor": "Nano-photocurrent mapping of local electronic structure in twisted\n  bilayer graphene: We report a combined nano-photocurrent and infrared nanoscopy study of\ntwisted bilayer graphene (TBG) enabling access to the local electronic\nphenomena at length scales as short as 20 nm. We show that the photocurrent\nchanges sign at carrier densities tracking the local superlattice density of\nstates of TBG. We use this property to identify domains of varying local twist\nangle by local photo-thermoelectric effect. Consistent with the photocurrent\nstudy, infrared nano-imaging experiments reveal optical conductivity features\ndominated by twist-angle dependent interband transitions. Our results provide a\nfast and robust method for mapping the electronic structure of TBG and suggest\nthat similar methods can be broadly applied to probe electronic inhomogeneities\nof moir\\'e superlattices in other van der Waals heterostructures.",
        "positive": "Unexpected hole doping of graphene by osmium adatoms: The electronic transport of monolayer graphene devices is studied before and\nafter \\emph{in situ} deposition of a sub-monolayer coating of osmium adatoms.\nUnexpectedly, and unlike all other metallic adatoms studied to date, osmium\nadatoms shift the charge neutrality point to more positive gate voltages. This\nindicates that osmium adatoms act as electron acceptors and thus leave the\ngraphene hole-doped. Analysis of transport data suggest that Os adatoms behave\nas charged impurity scatterers, albeit with a surprisingly low charge-doping\nefficiency. The charge neutrality point of graphene is found to vary\nnon-monotonically with gate voltage as the sample is warmed to room\ntemperature, suggesting that osmium diffuses on the surface but is not\ncompletely removed."
    },
    {
        "anchor": "Dynamical control of correlated states in a square quantum dot: In the limit of low particle density, electrons confined to a quantum dot\nform strongly correlated states termed Wigner molecules, in which the Coulomb\ninteraction causes the electrons to become highly localized in space. By using\nan effective model of Hubbard-type to describe these states, we investigate how\nan oscillatory electric field can drive the dynamics of a two-electron Wigner\nmolecule held in a square quantum dot. We find that, for certain combinations\nof frequency and strength of the applied field, the tunneling between various\ncharge configurations can be strongly quenched, and we relate this phenomenon\nto the presence of anti-crossings in the Floquet quasi-energy spectrum. We\nfurther obtain simple analytic expressions for the location of these\nanti-crossings, which allows the effective parameters for a given quantum dot\nto be directly measured in experiment, and suggests the exciting possibility of\nusing ac-fields to control the time evolution of entangled states in mesoscopic\ndevices.",
        "positive": "Surface Acoustic wave modulation of a coherently driven quantum dot in a\n  pillar microcavity: We report the efficient coherent photon scattering from a semiconductor\nquantum dot embedded in a pillar microcavity. We show that a surface acoustic\nwave can periodically modulate the energy levels of the quantum dot, but has a\nnegligible effect on the cavity mode. The scattered narrow-band laser is\nconverted to a pulsed single-photon stream, displaying an anti-bunching dip\ncharacteristic of single-photon emission. Multiple phonon sidebands are\nresolved in the emission spectrum, due to the absorption and emission of\nvibrational quanta in each scattering event."
    },
    {
        "anchor": "Double-periodic quasi-periodic graphene superlattice: non-Bragg band gap\n  and electronic transport: Electronic band gap and transport in quasi-periodic graphene superlattice of\ndouble-periodic sequence have been investigated. It is found that such\nquasi-periodic structure can possess a zero-averaged wave number\n(zero-$\\bar{k}$) gap which associated with an unusual Dirac point. Different\nfrom Bragg gap, the zero-$\\bar{k}$ gap is less sensitive to the incidence\nangle, and robust against the lattice constants. The locations of Dirac point\nand multi-Dirac-points in the graphene superlattices of various sequences are\nalso compared. The control of electron transport over the zero-$\\bar{k}$ band\ngap in graphene superlattice may facilitate the development of many\ngraphene-based electronics.",
        "positive": "Surfactant-Free Polar-to-Non-Polar-Phase Transfer of Exfoliated MoS2\n  Two-Dimensional Colloids: Exfoliation of lamellar materials into their corresponding layers represented\na breakthrough, due to the outstanding properties arising from the nanometric\nthickness confinement. Among the cleavage techniques, liquid-phase exfoliation\nis now on the rise because it is scalable and leads to easy-to-manipulate\ncolloids. However, all appropriate exfoliating solvents exhibit strong\npolarity, which restrains a lot the scope of feasible functionalization or\nprocessing of the resulting flakes. Here we propose to extend this scope,\ndemonstrating that nanosheets exfoliated in a polar medium can be properly\ndispersed in a non-polar solvent. To that purpose, we prepared suspensions of\nmolybdenum disulfide flakes in isopropanol/water and developed a phase transfer\nof the nanosheets to chloroform via precipitation and\nredispersion/centrifugation sequences, without any assisting surfactant. The\ncolloidal stability of the nanosheets in chloroform was found to be governed by\ntheir lateral dimensions and, although lower than in polar media, proved to be\nhigh enough to open the way to subsequent functionalization or processing of\nthe flakes in non-polar medium."
    },
    {
        "anchor": "Tuning hydrogen adsorption on graphene by gate voltage: In order to realize applications of hydrogen-adsorbed graphene, a main issue\nis how to control hydrogen adsorption/desorption at room temperature. In this\nstudy, we demonstrate the possibility to tune hydrogen adsorption on graphene\nby applying a gate voltage. The influence of the gate voltage on graphene and\nits hydrogen adsorption properties was investigated by electrical transport\nmeasurements, scanning tunneling microscopy, and density functional theory\ncalculations. We show that more hydrogen adsorbs on graphene with negative gate\nvoltage (p-type doping), compared to that without gate voltage or positive gate\nvoltage (n-type doping). Theoretical calculations explain the gate voltage\ndependence of hydrogen adsorption as modifications of the adsorption energy and\ndiffusion barrier of hydrogen on graphene by charge doping.",
        "positive": "Cryogenic Cooling and Power Generation Using Quantum Hall Systems: The possibility of using quantum Hall systems for thermoelectric energy\nconversion is investigated. It is shown that the massive degeneracy and the\nmetallicity of a partially-filled Landau level enable thermoelectric cooling\nand power generation with unprecedented efficiency at low temperature. The\nfigure of merit is explicitly derived for a transverse thermoelectric device\nusing the $\\nu=0$ quantum Hall state of Dirac materials at charge neutrality,\nwhere due to electron-hole symmetry electrical Hall effect vanishes but\nthermoelectric Hall effect peaks."
    },
    {
        "anchor": "Probing the localization length of photo-generated charges in organic\n  materials: We report a new experimental method to measure the localization length of\nphoto-generated carriers in an organic donor-acceptor photovoltaic blend by\ncomparing their dielectric and electron spin-resonance susceptibilities which\nare simultaneously measured by monitoring the resonance frequency of a\nsuperconducting resonator. We show that at cryogenic temperatures excitons are\ndissociated into long lived states, but that these are confined within a\nseparation of around $4\\;{\\rm nm}$. We determine the Debye and recombination\ntimes, showing the coexistence of a fast electrical response corresponding to\ndelocalized motion, with glass-like recombination kinetics.",
        "positive": "Internal Stark effect of single-molecule fluorescence: The optical properties of chromophores can be efficiently tuned by\nelectrostatic fields generated in their close environment, a phenomenon that\nplays a central role for the optimization of complex functions within living\norganisms where it is known as internal Stark effect (ISE). Here, we realised\nan ISE experiment at the lowest possible scale, by monitoring the Stark shift\ngenerated by charges confined within a single chromophore on its emission\nenergy. To this end, a scanning tunneling microscope (STM) functioning at\ncryogenic temperatures is used to sequentially remove the two central protons\nof a free-base phthalocyanine chromophore deposited on a NaCl-covered Ag(111)\nsurface. STM-induced fluorescence measurements reveal spectral shifts that are\nassociated to the electrostatic field generated by the internal charges\nremaining in the chromophores upon deprotonation."
    },
    {
        "anchor": "Ultrafast Dynamic Metallization of Dielectric Nanofilms by Strong\n  Single-Cycle Optical Fields: We predict a dynamic metallization effect where an ultrafast (single-cycle)\noptical pulse with a field less or on the order of 1 V/Angstrom causes\nplasmonic metal-like behavior of a dielectric film with a few-nm thickness.\nThis manifests itself in plasmonic oscillations of polarization and a\nsignificant population of the conduction band evolving on a femtosecond time\nscale. These phenomena are due a combination of both adiabatic (reversible) and\ndiabatic (for practical purposes irreversible) pathways.",
        "positive": "Entangling Distant Spin qubits via a Magnetic Domain Wall: The scalability of quantum networks based on solid-state spin qubits is\nhampered by the short range of natural spin-spin interactions. Here, we propose\na scheme to entangle distant spin qubits via the soft modes of an\nantiferromagnetic domain wall (DW). As spin qubits, we focus on quantum\nimpurities (QI's) placed in the vicinity of an insulating antiferromagnetic\nthin film. The low-energy modes harbored by the DW are embedded in the\nantiferromagnetic bulk, whose intrinsic spin-wave dynamics have a gap that can\nexceed the THz range. By setting the QI frequency and the temperature well\nwithin the bulk gap, we focus on the dipolar interaction between the QI and two\nsoft modes localized at the DW. One is a string-like mode associated with\ntransverse displacements of the DW position, while the dynamics of the other,\ncorresponding to planar rotations of the Neel order parameter, constitute a\nspin superfluid. By choosing the geometry in which the QI does not couple to\nthe string mode, we use an external magnetic field to control the gap of the\nspin superfluid and the qubit-qubit coupling it engenders. We suggest that a\ntunable micron-range coherent coupling between qubits can be established using\ncommon antiferromagnetic materials."
    },
    {
        "anchor": "Interplay of quantum spin Hall effect and spontaneous time-reversal\n  symmetry breaking in electron-hole bilayers I: Transport properties: The band-inverted electron-hole bilayers, such as InAs/GaSb, are an\ninteresting playground for the interplay of quantum spin Hall effect and\ncorrelation effects because of the small density of electrons and holes and the\nrelatively small hybridization between the electron and hole bands. It has been\nproposed that Coulomb interactions lead to a time-reversal symmetry broken\nphase when the electron and hole densities are tuned from the trivial to the\nquantum spin Hall insulator regime. We show that the transport properties of\nthe system in the time-reversal symmetry broken phase are consistent with the\nrecent experimental observations in InAs/GaSb. Moreover, we carry out a quantum\ntransport study on a Corbino disc where the bulk and edge contributions to the\nconductance can be separated. We show that the edge becomes smoothly conducting\nand the bulk is always insulating when one tunes the system from the trivial to\nthe quantum spin Hall insulator phase, providing unambiguous transport\nsignatures of the time-reversal symmetry broken phase.",
        "positive": "Entanglement signatures of quantum Hall phase transitions: We study quantum phase transitions involving fractional quantum Hall states,\nusing numerical calculations of entanglements and related quantities. We tune\nfinite-size wavefunctions on spherical geometries, by varying the interaction\npotential away from the Coulomb interaction. We uncover signatures of quantum\nphase transitions contained in the scaling behavior of the entropy of\nentanglement between two parts of the sphere. In addition to the entanglement\nentropy, we show that signatures of quantum phase transitions also appear in\nother aspects of the reduced density matrix of one part of the sphere."
    },
    {
        "anchor": "Phonon modulation of the spin-orbit interaction as a spin relaxation\n  mechanism in quantum dots: We calculate the spin relaxation rates in a parabolic InSb quantum dots due\nto the spin interaction with acoustical phonons. We considered the deformation\npotential mechanism as the dominant electron-phonon coupling in the\nPavlov-Firsov spin-phonon Hamiltonian. By studying suitable choices of magnetic\nfield and lateral dot size, we determine regions where the spin relaxation\nrates can be practically suppressed. We analyze the behavior of the spin\nrelaxation rates as a function of an external magnetic field and mean quantum\ndot radius. Effects of the spin admixture due to Dresselhaus contribution to\nspin-orbit interaction are also discussed.",
        "positive": "Phonons in Molecular Quantum Dots: Density Functional Calculation of\n  Franck-Condon Emission Rates in External Fields: We report the calculation of various phonon overlaps and their corresponding\nphonon emission probabilities for the problem of an electron tunneling onto and\noff of the buckyball-dimer molecular quantum dot $C_{72}$, both with and\nwithout the influence of an external field. We show that the stretch mode of\nthe two balls of the dumbbell couples most strongly to the electronic\ntransition, and in turn that a field in the direction of the bond between the\ntwo $C_{36}$ balls is most effective at further increasing the phonon emission\ninto the stretch mode. As the field is increased, phonon emission increases in\nprobability with an accompanying decrease in probability of the dot remaining\nin the ground vibrational state. We also present a simple model to gauge the\neffect of molecular size on the phonon emission of molecules similar to our\n$C_{72}$ molecule, including the experimentally tested $C_{140}$. In our\napproach we do not assume that the hessians of the molecule are identical for\ndifferent charge states. Our treatment is hence a generalization of the\ntraditional phonon overlap calculations for coupled electron-photon transition\nin solids."
    },
    {
        "anchor": "Influence of defect-induced deformations on electron transport in carbon\n  nanotubes: We theoretically investigate the influence of defect-induced long-range\ndeformations in carbon nanotubes on their electronic transport properties. To\nthis end we perform numerical ab-initio calculations using a\ndensity-functional-based tight-binding (DFTB) model for various tubes with\nvacancies. The geometry optimization leads to a change of the atomic positions.\nThere is a strong reconstruction of the atoms near the defect (called\n\"distortion\") and there is an additional long-range deformation. The impact of\nboth structural features on the conductance is systematically investigated. We\ncompare short and long CNTs of different kinds with and without long-range\ndeformation. We find for the very thin (9,0)-CNT that the long-range\ndeformation additionally affects the transmission spectrum and the conductance\ncompared to the short-range lattice distortion. The conductance of the larger\n(11,0)- or the (14,0)-CNT is overall less affected implying that the influence\nof the long-range deformation decreases with increasing tube diameter.\nFurthermore, the effect can be either positive or negative depending on the CNT\ntype and the defect type. Our results indicate that the long-range deformation\nmust be included in order to reliably describe the electronic structure of\ndefective, small-diameter zigzag tubes.",
        "positive": "Efficient Computation of Kubo Conductivity for Incommensurate 2D\n  Heterostructures: Here we introduce a numerical method for computing conductivity via the Kubo\nFormula for incommensurate 2D bilayer heterostructures using a tight-binding\nframework. We begin with deriving the momentum space formulation and Kubo\nFormula from the real space tight-binding model using the appropriate Bloch\ntransformation operator. We further discuss the resulting algorithm along with\nits convergence rate and computation cost in terms of parameters such as\nrelaxation time and temperature. In particular, we show that for low\nfrequencies, low temperature, and long relaxation times conductivity can be\ncomputed very efficiently using momentum space for a wide class of materials.\nWe then demonstrate our method by computing conductivity for twisted bilayer\ngraphene (tBLG) for small twist angles."
    },
    {
        "anchor": "Current-induced spin polarization at the surface of metallic films: a\n  theorem and an ab initio calculation: The broken inversion symmetry at the surface of a metallic film (or, more\ngenerally, at the interface between a metallic film and a different metallic or\ninsulating material) greatly amplifies the influence of the spin-orbit\ninteraction on the surface properties. The best known manifestation of this\neffect is the momentum-dependent splitting of the surface state energies\n(Rashba effect). Here we show that the same interaction also generates a\nspin-polarization of the bulk states when an electric current is driven through\nthe bulk of the film. For a semi-infinite jellium model, which is\nrepresentative of metals with a closed Fermi surface, we prove as a theorem\nthat, regardless of the shape of the confinement potential, the induced surface\nspin density at each surface is given by ${\\bf S} =-\\gamma \\hbar {\\bf \\hat\nz}\\times {\\bf j}$, where ${\\bf j}$ is the particle current density in the bulk,\n${\\bf \\hat z}$ the unit vector normal to the surface, and\n$\\gamma=\\frac{\\hbar}{4mc^2}$ contains only fundamental constants. For a general\nmetallic solid $\\gamma$ becomes a material-specific parameter that controls the\nstrength of the interfacial spin-orbit coupling. Our theorem, combined with an\n{\\it ab initio} calculation of the spin polarization of the current-carrying\nfilm, enables a determination of $\\gamma$, which should be useful in modeling\nthe spin-dependent scattering of quasiparticles at the interface.",
        "positive": "Catalyst-Free Growth of Millimeter-Long Topological Insulator Bi2Se3\n  Nanoribbons and the Observation of pi Berry Phase: We report the growth of single-crystalline Bi2Se3 nanoribbons with lengths up\nto several millimeters via a catalyst-free physical vapor deposition method.\nScanning transmission electron microscopy analysis reveals that the nanoribbons\ngrow along the (1120) direction. We obtain a detailed characterization of the\nelectronic structure of the Bi2Se3 nanoribbons from measurements of\nShubnikov-de Haas (SdH) quantum oscillations. Angular dependent\nmagneto-transport measurements reveal a dominant two-dimensional contribution\noriginating from surface states and weak contribution from the bulk states. The\ncatalyst-free synthesis yields high-purity nanocrystals enabling the\nobservation of a large number of SdH oscillation periods and allowing for an\naccurate determination of the pi-Berry phase, one of the key features of Dirac\nfermions in topological insulators. The long-length nanoribbons can empower the\npotential for fabricating multiple nanoelectronic devices on a single\nnanoribbon."
    },
    {
        "anchor": "Ballistic transport properties in pristine-doped-pristine graphene\n  junctions: We investigate the ballistic electron transport in a monolayer graphene with\nconfigurational averaged impurities, located between two clean graphene leads.\nIt is shown that the electron transmission are strongly dependent on the\nconcentration of impurities and the incident energy. In turn, the conductance\ncomputed using the Landauer formalism shows a similar behavior to those found\nin experimental works as a function of the applied voltage for different\nconcentrations of impurities in the limit of low temperatures. In the limit of\nzero bias voltage, the conductance shows a minimum value which reduces to zero\nfor high concentration of impurities which disentangle graphene sublattices.\nThese results can be very helpful for exploring the tunneling mechanism of\nelectrons through doped thermodynamically stable graphene.",
        "positive": "Domain wall attraction and repulsion during spin-torque-induced coherent\n  motion: We calculate the interaction between two magnetic domain walls during their\ncurrent-induced motion. This interaction produces a separation-dependent\nresistance and also a differential velocity, causing domains in motion to\nexperience an effective attraction at large separations and an effective\nrepulsion at short separations. In an intermediate range of currents the two\ndomain walls will reach a natural equilibrium spacing that depends on the\nmagnitude of the current flowing through the material."
    },
    {
        "anchor": "Majorana zero-modes in a dissipative Rashba nanowire: Condensed matter systems are continuously subjected to dissipation, which\noften has adverse effects on quantum phenomena. We focus on the impact of\ndissipation on a superconducting Rashba nanowire. We reveal that the system can\nstill host Majorana zero-modes (MZMs) with a finite lifetime in the presence of\ndissipation. Most interestingly, dissipation can also generate two kinds of\ndissipative boundary states: four robust zero-modes (RZMs) and two MZMs, in the\nregime where the non-dissipative system is topologically trivial. The MZMs\nappear via bulk gap closing and are topologically characterized by a winding\nnumber. The RZMs are not associated with any bulk states and possess no winding\nnumber, but their emergence is instead tied to exceptional points. Further, we\nconfirm the stability of the dissipation-induced RZMs and MZMs in the presence\nof random disorder. Our study paves the way for both realizing and stabilizing\nMZMs in an experimental setup, driven by dissipation.",
        "positive": "Universal chiral magnetic effect in the vortex lattice of a Weyl\n  superconductor: It was shown recently that Weyl fermions in a superconducting vortex lattice\ncan condense into Landau levels. Here we study the chiral magnetic effect in\nthe lowest Landau level: The appearance of an equilibrium current $I$ along the\nlines of magnetic flux $\\Phi$, due to an imbalance between Weyl fermions of\nopposite chirality. A universal contribution $dI/d\\Phi=(e/h)^2\\mu$ (at\nequilibrium chemical potential $\\mu$ relative to the Weyl point) appears when\nquasiparticles of one of the two chiralities are confined in vortex cores. The\nconfined states are charge-neutral Majorana fermions."
    },
    {
        "anchor": "Electron spin transport driven by surface plasmon polariton: We propose a mechanism of angular momentum conversion from optical transverse\nspin in surface plasmon polaritons (SPPs) to conduction electron spin. Free\nelectrons in the metal follow the transversally spinning electric field of SPP,\nand the resulting orbital motions create inhomogeneous static magnetisation in\nthe metal. By solving the spin diffusion equation in the SPP, we find that the\nmagnetisation field generates an electron spin current. We show that there\nexists a resonant condition where the spin current is resonantly enhanced, and\nthe polarisation of the spin current is flipped. Our theory reveals a novel\nfunctionality of SPP as a spin current source.",
        "positive": "Massive thermal fluctuation of massless graphene electrons: Whereas thermal current noise $\\langle I^2 \\rangle$ in typical conductors is\nproportional to temperature $T$, $\\langle I^2 \\rangle$ in graphene exhibits a\nnonlinear $T$ dependence due to the massless nature of individual electrons.\nThis unique $\\langle I^2 \\rangle$ arising from individually massless electrons\nis intimately linked to the non-zero collective mass of graphene electrons;\nnamely, $\\langle I^2 \\rangle$ is set by the equipartition theorem applied to\nthe collective mass's kinetic energy, with the nonlinear $T$-dependence arising\nfrom the $T$-dependence of the collective mass. This link between thermal\nfluctuation and collective dynamics unifies $\\langle I^2 \\rangle$ in graphene\nand typical conductors, while elucidating the uniqueness of the former at the\nsame time."
    },
    {
        "anchor": "Strong Electron-Hole Exchange in Coherently Coupled Quantum Dots: We have investigated few-body states in vertically stacked quantum dots. Due\nto small inter-dot tunneling rate, the coupling in our system is in a\npreviously unexplored regime where electron-hole exchange is the dominant spin\ninteraction. By tuning the gate bias, we are able to turn this coupling off and\nstudy a complementary regime where total electron spin is a good quantum\nnumber. The use of differential transmission allows us to obtain unambiguous\nsignatures of the interplay between electron and hole spin interactions. Small\ntunnel coupling also enables us to demonstrate all-optical charge sensing,\nwhere conditional exciton energy shift in one dot identifies the charging state\nof the coupled partner.",
        "positive": "Giant oscillations in a triangular network of one-dimensional states in\n  marginally twisted graphene: The electronic properties of graphene superlattices have attracted intense\ninterest that was further stimulated by the recent observation of novel\nmany-body states at \"magic\" angles in twisted bilayer graphene (BLG). For very\nsmall (\"marginal\") twist angles of 0.1 deg, BLG has been shown to exhibit a\nstrain-accompanied reconstruction that results in submicron-size triangular\ndomains with the Bernal stacking. If the interlayer bias is applied to open an\nenergy gap inside the domain regions making them insulating, marginally-twisted\nBLG is predicted to remain conductive due to a triangular network of chiral\none-dimensional (1D) states hosted by domain boundaries. Here we study electron\ntransport through this network and report giant Aharonov-Bohm oscillations\npersisting to temperatures above 100 K. At liquid helium temperatures, the\nnetwork resistivity exhibits another kind of oscillations that appear as a\nfunction of carrier density and are accompanied by a sign-changing Hall effect.\nThe latter are attributed to consecutive population of the flat minibands\nformed by the 2D network of 1D states inside the gap. Our work shows that\nmarginally twisted BLG is markedly distinct from other 2D electronic systems,\nincluding BLG at larger twist angles, and offers a fascinating venue for\nfurther research."
    },
    {
        "anchor": "Spin-polarized electric currents in quantum transport through tubular\n  two-dimensional electron gases: Scattering theory is employed to derive a Landauer-type formula for the spin\nand the charge currents, through a finite region where spin-orbit interactions\nare effective. It is shown that the transmission matrix yields the spatial\ndirection and the magnitude of the spin polarization. This formula is used to\nstudy the currents through a tubular two-dimensional electron gas. In this\ncylindrical geometry, which may be realized in experiment, the transverse\nconduction channels are not mixed (provided that the spin-orbit coupling is\nuniform). It is then found that for modest boundary scattering, each step in\nthe quantized conductance is split into two, and the new steps have a non-zero\nspin conductance, with the spin polarization perpendicular to the direction of\nthe current.",
        "positive": "Exciton-polariton wakefields in semiconductor microcavities: We consider the excitation of polariton wakefields due to a propagating\nsource in a semiconductor micro cavity. We show that two kinds of wakes are\npossible, depending on the constituents fraction (either exciton or photon) of\nthe polariton wavefunction. The nature of the wakefields (pure excitonic or\npolaritonic) can be controled by changing the speed of propagation of the\nexternal pump. This process could be used as a diagnostic for the internal\nparameters of the microcavity."
    },
    {
        "anchor": "Theoretical investigation of the electron velocity in quantum Hall bars,\n  in the out of linear response regime: We report on our theoretical investigation of the electron velocity in\n(narrow) quantum-Hall systems, considering the out-of-linear-response regime.\nThe electrostatic properties of the electron system are obtained by the\nThomas-Fermi-Poisson nonlinear screening theory. The electron velocity\ndistribution as a function of the lateral coordinate is obtained from the slope\nof the screened potential within the incompressible strips (ISs). The asymmetry\ninduced by the imposed current on the ISs is investigated, as a function of the\ncurrent intensity and impurity concentration. We find that the width of the IS\non one side of the sample increases linearly with the intensity of the applied\ncurrent and decreases with the impurity concentration.",
        "positive": "Electrical control of optical orientation of neutral and negatively\n  charged excitons in n-type semiconductor quantum well: We report a giant electric field induced increase of spin orientation of\nexcitons in n-type GaAs/AlGaAs quantum well. It correlates strongly with the\nformation of negatively charged excitons (trions) in the photoluminescence\nspectra. Under resonant excitation of neutral heavy-hole excitons, the\npolarization of excitons and trions increases dramatically with electrical\ninjection of electrons within the narrow exciton-trion bias transition in the\nPL spectra, implying a polarization sensitivity of 200 % per Volt. This effect\nresults from a very efficient trapping of neutral excitons by the quantum well\ninterfacial fluctuations (so-called \"natural\" quantum dots) containing resident\nelectrons."
    },
    {
        "anchor": "Two orders of magnitude reduction in silicon membrane thermal\n  conductivity by resonance hybridizations: The thermal conductivity of a freestanding single-crystal silicon membrane\nmay be reduced significantly by attaching nanoscale pillars on one or both\nsurfaces. Atomic resonances of the nanopillars locally and intrinsically couple\nwith the base membrane phonon modes causing these modes to hybridize and\nflatten at each coupling location in the phonon band structure. The ensuing\ngroup velocity reductions, which in principle may be tuned to take place across\nsilicon's full spectrum, lead to a lowering of the in-plane thermal\nconductivity in the base membrane. Using equilibrium molecular dynamics\nsimulations, we report a staggering two orders of magnitude reduction in the\nthermal conductivity at room temperature by this mechanism.",
        "positive": "Exact Analytic Results for Composite Fermions in a Rajaraman-Sondhi like\n  formulation: We obtain the exact spectrum and the unique ground state of two composite\nfermions (in a Rajaraman - Sondhi like formulation) in an external magnetic\nfield $B$. We show that the energy eigenvalues decrease with increasing angular\nmomentum, thus making it energetically favourable for composite fermions to\nstay apart. Generalising this result to a gas of composite fermions, we provide\nan energetic justification of the Laughlin and Jain wave-functions."
    },
    {
        "anchor": "Specific heat measurement of mesoscopic loops: We report highly sensitive specific heat measurement on mesoscopic\nsuperconducting loops at low temperature. These mesoscopic systems exhibit\nthermal properties significantly different from that of the bulk materials. The\nmeasurement is performed on a silicon membrane sensor where 450 000\nsuperconducting aluminium loops are deposited through electron beam lithography\nunder an applied magnetic field. Each entry of a vortex is associated to a jump\nin the specific heat of few thousands of Boltzmann constant kB indicating the\nexistence of phase transitions. The periodicity of this sequential phase\ntransitions is a nontrivial behaviour and varies strongly as the temperature is\ndecreased. The successive phase transitions are well described by the\nGinzburg-Landau theory of superconductivity. The presence of metastable states\nis responsible for the n-&#61510;0 (n=1, 2, 3...) periodicity of the\ndiscontinuities of the measured specific heat.",
        "positive": "Statistics of radiation emitted from a quantum point contact: We analyze the statistics of the electromagnetic radiation emitted from\nelectrons pushed through a quantum point contact. We consider a setup\nimplemented in a two-dimenional electron gas (2DEG) where the radiation\nmanifests itself in terms of 2D plasmons emitted from electrons scattered at\nthe point contact. The bosonic statistics of the plasmons competes with the\nfermionic statistics of the electrons; as a result, the quantum point contact\nemits non-classical radiation with a statistics which can be tuned from\nbunching to anti-bunching by changing the driving voltage. Our perturbative\ncalculation of the irreducible two-plasmon probability correlator provides us\nwith information on the statistical nature of the emitted plasmons and on the\nunderlying electronic current flow."
    },
    {
        "anchor": "Suppressing nano-scale stick-slip motion by feedback: When a micro cantilever with a nano-scale tip is manipulated on a substrate\nwith atomic-scale roughness, the periodic lateral frictional force and\nstochastic fluctuations may induce stick-slip motion of the cantilever tip,\nwhich greatly decreases the precision of the nano manipulation. This unwanted\nmotion cannot be reduced by open-loop control especially when there exist\nparameter uncertainties in the system model, and thus needs to introduce\nfeedback control. However, real-time feedback cannot be realized by the\nexisting virtual reality virtual feedback techniques based on the position\nsensing capacity of the atomic force microscopy (AFM). To solve this problem,\nwe propose a new method to design real-time feedback control based on the force\nsensing approach to compensate for the disturbances and thus reduce the\nstick-slip motion of the cantilever tip. Theoretical analysis and numerical\nsimulations show that the controlled motion of the cantilever tip tracks the\ndesired trajectory with much higher precision. Further investigation shows that\nour proposal is robust under various parameter uncertainties. Our study opens\nup new perspectives of real-time nano manipulation.",
        "positive": "Interband coherence induced correction to Thouless pumping: possible\n  observation in cold-atom systems: In Thouless pump, the charge transport in a one-dimensional insulator over an\nadiabatic cycle is topologically quantized. For nonequilibrium initial states,\nhowever, interband coherence will induce a previously unknown contribution to\nThouless pumping. Though not geometric in nature, this contribution is\nindependent of the time scale of the pumping protocol. In this work, we perform\na detailed analysis of our previous finding [Phys. Rev. B 91, 085420 (2015)] in\nan already available cold-atom setup. We show that initial states with\ninterband coherence can be obtained via a quench of the system's Hamiltonian.\nAdiabatic pumping in the post-quench system are then examined both\ntheoretically and numerically, in which the interband coherence is shown to\nplay an important role and can hence be observed experimentally. By choosing\nadiabatic protocols with different switching-on speeds, we also show that the\ncontribution of interband coherence to adiabatic pumping can be tuned. It is\nfurther proposed that the interband coherence induced correction to Thouless\npumping may be useful in capturing a topological phase transition point. All\nour results have direct experimental interests."
    },
    {
        "anchor": "Understanding electron behavior in strained graphene as a reciprocal\n  space distortion: The behavior of electrons in strained graphene is usually described using\neffective pseudomagnetic fields in a Dirac equation. Here we consider the\nparticular case of a spatially constant strain. Our results indicate that\nlattice corrections are easily understood using a strained reciprocal space, in\nwhich the whole energy dispersion is simply shifted and deformed. This leads to\na directional dependent Fermi velocity without producing pseudomagnetic fields.\nThe corrections due to atomic wavefunction overlap changes tend to compensate\nsuch effects. Also, the analytical expressions for the shift of the Dirac\npoints as well as the corresponding Dirac equation are found. In view of the\nformer results, we discuss the range of applicability of the usual approach of\nconsidering pseudomagnetic fields in a Dirac equation derived from the old\nDirac points of the unstrained lattice. Such considerations are important if a\ncomparison is desired with experiments or numerical simulations.",
        "positive": "Raman spectroscopy and strain mapping in individual Ge-SixGe1-x\n  core-shell nanowires: Core-shell Ge-SixGe1-x nanowires (NWs) are expected to contain large strain\nfields due to the lattice-mismatch at the core/shell interface. Here we report\nthe measurement of core strain in a NW heterostructure using Raman\nspectroscopy. We compare the Raman spectra, and the frequency of the Ge-Ge mode\nmeasured in individual Ge-Si0.5Ge0.5 core-shell, and bare Ge NWs. We find that\nthe Ge-Ge mode frequency is diameter-independent in GeNWs with a value similar\nto that of bulk Ge, 300.5 cm-1. On the other hand, Ge-Si0.5Ge0.5 core-shell\nnanowires reveal a strain-induced blue shift of the Ge-Ge mode, dependent on\nthe relative core and shell thicknesses. Using lattice dynamical theory we\ndetermine the strain in the Ge core, and show that the results are in good\nagreement with values calculated using a continuum elasticity model."
    },
    {
        "anchor": "$\\mathbb{Z}_{2}$ Topological Index for Continuous Photonic Materials: Electronic topological insulators are one of the breakthroughs of the 21st\ncentury condensed matter physics. So far, the search for a light counterpart of\nan electronic topological insulator has remained elusive. This is due to the\nfundamentally different natures of light and matter and the different spins of\nphotons and electrons. Here, it is shown that the theory of electronic\ntopological insulators has a genuine analogue in the context of light wave\npropagation in time-reversal invariant continuous materials. We introduce a\nGauge invariant $Z_2$ index that depends on the global properties of the\nphotonic band structure and is robust to any continuous weak variation of the\nmaterial parameters that preserves the time-reversal invariance. A nontrivial\n$Z_2$ index has two possible causes: (i) the lack of smoothness of the\npseudo-Hamiltonian in the ${\\bf{k}} \\to \\infty$ limit, and (ii) the\nentanglement between positive and negative frequency eigenmode branches. In\nparticular, it is proven that electric-type plasmas and magnetic-type plasmas\nare topologically inequivalent for a fixed wave polarization. We propose a\nbulk-edge correspondence that links the number of edge modes with the\ntopological invariants of two continuous bulk materials, and present detailed\nnumerical examples that illustrate the application of the theory.",
        "positive": "Proposal for teleportation of charge qubits via superradiance: A scheme is proposed to teleport charge qubits via superradiance.\nReservoir-induced entanglement is generated between two semiconductor dots in a\nmicrocavity where a quantum state encoded in a third quantum dot is then tuned\ninto collective decay with one of the entangled dots. Teleportation is achieved\nautomatically in our scheme which we also extend to quantum wires."
    },
    {
        "anchor": "Multistability and Self-Organization in Disordered SQUID Metamaterials: Planar arrays of magnetoinductively coupled rf SQUIDs belong to the emergent\nclass of superconducting metamaterials that encompass the Josephson effect.\nSQUID metamaterials acquire their electromagnetic properties from the resonant\ncharacteristics of their constitutive elements, i.e., the individual rf SQUIDs,\nwhich consist of a superconducting ring interrupted by a Josephson junction. We\ninvestigate the response of a two-dimensional SQUID metamaterial to frequency\nvariation of an applied alternating magnetic field in the presence of disorder,\narising from critical current fluctuations of the Josephson elements; in\neffect, the resonance frequencies of individual SQUIDs are distributed randomly\naround a mean value. Bistability is observed in the total current-frequency\ncurves both in ordered and disordered SQUID metamaterials; moreover,\nbistability is favoured by disorder through the improvement of synchronization\nbetween SQUID oscillators. Relatively weak disorder widens significantly the\nbistability region by helping the system to self-organize itself and leads to\nnearly homogeneous states that change smoothly with varying frequency.\nMoreover, the total current of the metamaterial is enhanced compared with that\nof uncoupled SQUIDs, through the synergetic action of coupling and\nsynchronization. Multistability of nearly homogeneous states allows the\nmetamaterial to exhibit different magnetic responses corresponding to different\nvalues of the magnetic permeability. At low power of the incident field,\nhigh-current states exhibit extreme diamagnetic properties corresponding to\nnegative magnetic permeability in a narrow frequency region.",
        "positive": "Identification of excitons, trions and biexcitons in single-layer WS2: Single-layer WS$_2$ is a direct-gap semiconductor showing strong excitonic\nphotoluminescence features in the visible spectral range. Here, we present\ntemperature-dependent photoluminescence measurements on mechanically exfoliated\nsingle-layer WS$_2$, revealing the existence of neutral and charged excitons at\nlow temperatures as well as at room temperature. By applying a gate voltage, we\ncan electrically control the ratio of excitons and trions and assert a residual\nn-type doping of our samples. At high excitation densities and low\ntemperatures, an additional peak at energies below the trion dominates the\nphotoluminescence, which we identify as biexciton emission."
    },
    {
        "anchor": "Bulk cyclotron resonance in the topological insulator Bi2Te3: We investigated magneto-optical response of undoped Bi2Te3 films in the\nterahertz frequency range (0.3 - 5.1 THz, 10 - 170 cm-1) in magnetic fields up\nto 10 T. The optical transmission, measured in the Faraday geometry, is\ndominated by a broad Lorentzian-shaped mode, whose central frequency linearly\nincreases with applied field. In zero field, the Lorentzian is centered at zero\nfrequency, representing hence the free-carrier Drude response. We interpret the\nmode as a cyclotron resonance (CR) of free carriers in Bi2Te3. Because the\nmode's frequency position follows a linear magnetic-field dependence and\nbecause undoped Bi2Te3 is known to possess an appreciable number of bulk\ncarriers, we associate the mode with a bulk CR. In addition, the cyclotron mass\nobtained from our measurements fits well the literature data on the bulk\neffective mass in Bi2Te3. Interestingly, the width of the CR mode demonstrates\na behavior non-monotonous in field. We propose that the CR width is defined by\ntwo competing factors: impurity scattering, which rate decreases in increasing\nfield, and electron-phonon scattering, which rate exhibits the opposite\nbehavior.",
        "positive": "Sub-100 nm Skyrmions at Zero Magnetic Field in Ir/Fe/Co/Pt\n  Nanostructures: Magnetic skyrmions are chiral spin structures that have recently been\nobserved at room temperature (RT) in multilayer thin films. Their topological\nstability should enable high scalability in confined geometries - a\nsought-after attribute for device applications. While umpteen theoretical\npredictions have been made regarding the phenomenology of sub-100 nm skyrmions\nconfined in dots, in practice their formation in the absence of an external\nmagnetic field and evolution with confinement remain to be established. Here we\ndemonstrate the confinement-induced stabilization of sub-100 nm RT skyrmions at\nzero field (ZF) in Ir/Fe(x)/Co(y)/Pt nanodots over a wide range of magnetic and\ngeometric parameters. The ZF skyrmion size can be as small as ~50 nm, and\nvaries by a factor of 4 with dot size and magnetic parameters. Crucially,\nskyrmions with varying thermodynamic stability exhibit markedly different\nconfinement phenomenologies. These results establish a comprehensive foundation\nfor skyrmion phenomenology in nanostructures, and provide immediate directions\nfor exploiting their properties in nanoscale devices."
    },
    {
        "anchor": "Controlling observables in time-dependent quantum transport: The theory of time-dependent quantum transport addresses the question: How do\nelectrons flow through a junction under the influence of an external\nperturbation as time goes by? In this paper, we invert this question and search\nfor a time-dependent bias such that the system behaves in a desired way. This\ncan, for example, be an observable that is forced to follow a certain pattern\nor the minimization of an objective function which depends on the observables.\nOur system of choice consists of quantum dots coupled to normal or\nsuperconducting leads. We present results for junctions with normal leads where\nthe current, the density or a molecular vibration is optimized to follow a\ngiven target pattern. For junctions with two superconducting leads, where the\nJosephson effect triggers the current to oscillate, we show how to suppress the\nJosephson oscillations by suitably tailoring the bias. In a second example\ninvolving superconductivity, we consider a Y shaped junction with two quantum\ndots coupled to one superconducting and two normal leads. This device is used\nas a Cooper pair splitter to create entangled electrons on the two quantum\ndots. We maximize the splitting efficiency with the help of an optimized bias.",
        "positive": "Spin and valley quantum Hall ferromagnetism in graphene: In a graphene Landau level (LL), strong Coulomb interactions and the fourfold\nspin/valley degeneracy lead to an approximate SU(4) isospin symmetry. At\npartial filling, exchange interactions can spontaneously break this symmetry,\nmanifesting as additional integer quantum Hall plateaus outside the normal\nsequence. Here we report the observation of a large number of these quantum\nHall isospin ferromagnetic (QHIFM) states, which we classify according to their\nreal spin structure using temperature-dependent tilted field magnetotransport.\nThe large measured activation gaps confirm the Coulomb origin of the broken\nsymmetry states, but the order is strongly dependent on LL index. In the high\nenergy LLs, the Zeeman effect is the dominant aligning field, leading to real\nspin ferromagnets with Skyrmionic excitations at half filling, whereas in the\n`relativistic' zero energy LL, lattice scale anisotropies drive the system to a\nspin unpolarized state, likely a charge- or spin-density wave."
    },
    {
        "anchor": "Role of dephasing on the conductance signatures of Majorana zero modes: Conductance signatures that signal the presence of Majorana zero modes in a\nthree terminal nanowire-topological superconductor hybrid system are analyzed\nin detail, in both the clean nanowire limit and in the presence of non-coherent\ndephasing interactions. In the coherent transport regime for a clean wire, we\npoint out contributions of the local Andreev reflection and the non-local\ntransmissions toward the total conductance lineshapes while clarifying the role\nof contact broadening on the Majorana conductance lineshapes at the magnetic\nfield parity crossings. Interestingly, at larger $B$-field parity crossings,\nthe contribution of the Andreev reflection process decreases which is\ncompensated by the non-local processes in order to maintain the conductance\nquantum regardless of contact coupling strength. In the non-coherent transport\nregime, we include dephasing that is introduced by momentum randomization\nprocesses, that allows one to smoothly transition to the diffusive limit. Here,\nas expected, we note that while the Majorana character of the zero modes is\nunchanged, there is a reduction in the conductance peak magnitude that scales\nwith the strength of the impurity scattering potentials. Important distinctions\nbetween the effect of non-coherent dephasing processes and contact-induced\ntunnel broadenings in the coherent regime on the conductance lineshapes are\nelucidated. Most importantly our results reveal that the addition of dephasing\nin the set up does not lead to any notable length dependence to the conductance\nof the zero modes, contrary to what one would expect in a gradual transition to\nthe diffusive limit. We believe this work paves a way for a systematic\nintroduction of scattering processes into the realistic modeling of Majorana\nnanowire hybrid devices and assessing topological signatures in such systems in\nthe presence of non-coherent scattering processes.",
        "positive": "Photovoltaic Current Response of Mesoscopic Conductors to Quantized\n  Cavity Modes: We extend the analysis of the effects of electromagnetic (EM) fields on\nmesoscopic conductors to include the effects of field quantization, motivated\nby recent experiments on circuit QED. We show that in general there is a\nphotovoltaic (PV) current induced by quantized cavity modes at zero bias across\nthe conductor. This current depends on the average photon occupation number and\nvanishes identically when it is equal to the average number of thermal\nelectron-hole pairs. We analyze in detail the case of a chaotic quantum dot at\ntemperature T_e in contact with a thermal EM field at temperature T_f,\ncalculating the RMS size of the PV current as a function of the temperature\ndifference, finding an effect ~pA."
    },
    {
        "anchor": "Transport in a hybrid normal-topological superconductor Kondo model: We investigate the equilibrium and non-equilibrium transport through a\nquantum dot in the Kondo regime, embedded between a normal metal and a\ntopological superconductor supporting Majorana bound states at its end points.\nWe find that the Kondo physics is significantly modified by the presence of the\nMajorana modes. When the Majorana modes are coupled, aside from the Kondo scale\n$T_K$, a new energy scale $T^*\\ll T_K$ emerges, that controls the low energy\nphysics of the system. At low temperatures, the ac-conductance is suppressed\nfor frequencies below $T^*$, while the noise spectrum acquires a $\\sim\n\\omega^3$ dependence. At high temperatures, $T \\gg T_K$, the regular\nlogarithmic dependence in the differential conductance is also affected. Under\nnon-equilibrium conditions, and in particular in the $\\{T, B\\}\\to 0$ limit, the\ndifferential conductance becomes negative. These findings indicate that the\nchanges in transport may serve as clues for detecting the Majorana bound states\nin such systems. In terms of methods used, we characterize the transport by\nusing a combination of perturbative and renormalization group approaches.",
        "positive": "Universal conductance dips and fractional excitations in a two-subband\n  quantum wire: We theoretically investigate a quasi-one-dimensional quantum wire, where the\nlowest two subbands are populated, in the presence of a helical magnetic field.\nWe uncover a backscattering mechanism involving the helical magnetic field and\nCoulomb interaction between the electrons. The combination of these ingredients\nresults in scattering resonances and partial gaps which give rise to\nnon-standard plateaus and conductance dips at certain electron densities. The\npositions and values of these dips are independent of material parameters,\nserving as direct transport signatures of this mechanism. Our theory applies to\ngeneric quasi-one-dimensional systems, including a Kondo lattice and a quantum\nwire subject to intrinsic or extrinsic spin-orbit coupling. Observation of the\nuniversal conductance dips would identify a strongly correlated fermion system\nhosting fractional excitations, resembling the fractional quantum Hall states."
    },
    {
        "anchor": "Role of Centrosymmetry in the Photophysics of Molecular Aggregates: To understand the photophysics of molecular aggregates, exciton model of J-\nand H-aggregate has been extensively utilized. However, it lacks consideration\nof crystal symmetry. Although discrete molecules may lack symmetry, their\naggregates can exhibit a high degree of symmetry. Herein, we utilized group\ntheory to study the optical properties of centrosymmetric molecular aggregates,\nshowing that their optical selection rules (transition dipole moment and\nspin-orbit coupling) are determined by the symmetry of singlet and triplet\nexcited states and the intermolecular orbital overlap. Symmetry-forbidden\nelectronic transitions are closely related to ultralong organic\nphosphorescence. Our model's scope is broad, as over 50% of organic crystals\nbelong to centrosymmetric space groups according to Cambridge Structural\nDatabase.",
        "positive": "Curvature function renormalisation, topological phase transitions and\n  multicriticality: A recently proposed curvature renormalization group scheme for topological\nphase transitions defines a generic `curvature function' as a function of the\nparameters of the theory and shows that topological phase transitions are\nsignalled by the divergence of this function at certain parameters values,\ncalled critical points, in analogy with usual phase transitions. A\nrenormalization group procedure was also introduced as a way of flowing away\nfrom the critical point towards a fixed point, where an appropriately defined\ncorrelation function goes to zero and topological quantum numbers\ncharacterising the phase are easy to compute. In this paper, using two\nindependent models - a model in the AIII symmetry class and a model in the BDI\nsymmetry class - in one dimension as examples, we show that there are cases\nwhere the fixed point curve and the critical point curve appear to intersect,\nwhich turn out to be multi-critical points, and focus on understanding its\nimplications."
    },
    {
        "anchor": "Analysis of efficiency limiting processes in thin film Cu(In,Ga)(S,Se)2\n  electrodeposited solar cells: Electrodeposited thin film cells have been fabricated with record-breaking\nefficiencies of 11.4%. This presentation examines conversion mechanisms in\ncells with a focus on the effect of CdS buffer layers using a range of\ncomplementary tools. Dark currents (IVs) are well described by series and\nparallel resistances, and two dominant recombination mechanisms represented by\nparallel diodes. Measurements of IV as a function of temperature (IVT) allow\nextraction of activation energies corresponding to these processes and indicate\ntheir spatial position. Admittance spectroscopy (AS) gives an independent\nestimate of the same energies, and yields values of the defect densities of\nstates in the forbidden gap. Two dominant levels are apparent, confirming the\nvalidity of the IV analysis. Spectral response (QE) measurements are presented,\nyielding information on minority carrier collection efficiency. The different\nmethods of parameter extraction are correlated and indicate recombination\nlevels some hundreds of meV above the valence band and below the conduction\nband. Bias dependence of admittance spectroscopy gives indications on the\nlocalisation of defect centres with one defect situated at the CdS\nheterointerface and the other in the bulk of the depletion region. The dark\ncurrent analysis indicates that photogenerated minority carrier collection is\nthe limiting factor in these cells at the operating bias.",
        "positive": "Singlet-triplet transition in a single-electron transistor at zero\n  magnetic field: We report sharp peaks in the differential conductance of a single-electron\ntransistor (SET) at low temperature, for gate voltages at which charge\nfluctuations are suppressed. For odd numbers of electrons we observe the\nexpected Kondo peak at zero bias. For even numbers of electrons we generally\nobserve Kondo-like features corresponding to excited states. For the latter,\nthe excitation energy often decreases with gate voltage until a new zero-bias\nKondo peak results. We ascribe this behavior to a singlet-triplet transition in\nzero magnetic field driven by the change of shape of the potential that\nconfines the electrons in the SET."
    },
    {
        "anchor": "Circularly-Polarized Light Emission from Semiconductor Planar Chiral\n  Photonic Crystal: We proposed and demonstrated a scheme of surface emitting circularly\npolarized light source by introducing strong imbalance between left- and\nright-circularly polarized vacuum fields in an on-waveguide chiral grating\nstructure. We observed circularly polarized spontaneous emission from InAs\nquantum dots embedded in the wave guide region of a GaAs-based structure.\nObtained degree of polarization reaches as large as 25% at room temperature.\nNumerical calculation visualizes spatial profiles of the modification of vacuum\nfield modes inside the structure with strong circular anisotropy.",
        "positive": "Dynamic dependence to domain wall propagation through artificial spin\n  ice: Domain wall propagation dynamics have been studied in nanostructured\nartificial kagome spin ice structures. A stripline circuit has been used to\nprovide localised pulsed magnetic fields within the artificial spin ice\nstructure. This provides control of the system through electrically assisted\ndomain wall nucleation events. Synchronisation of the pulsed fields with\nadditional global magnetic fields and the use of a focussed magneto-optical\nKerr effect magnetometer allows our experiments to probe the domain wall\ntransit through an extended ASI structure. We find that the propagation\ndistance depends on the driving field revealing field driven properties of\ndomain walls below their intrinsic nucleation field."
    },
    {
        "anchor": "Non-equilibrium renormalised contacts for transport in nanodevices with\n  interaction: a quasi-particle approach: We present an application of a new formalism to treat the quantum transport\nproperties of fully interacting nanoscale junctions. We consider a model\nsingle-molecule nanojunction in the presence of two kinds of electron-vibron\ninteractions. In terms of the electron density matrix, one interaction is\ndiagonal in the central region and the second off-diagonal between the central\nregion and the left electrode. We use a non-equilibrium Green's function\ntechnique to calculate the system's properties in a self-consistent manner. The\ninteraction self-energies are calculated at the Hartree-Fock level in the\ncentral region and within a dynamical mean-field-like approach for the crossing\ninteraction. Our calculations are performed for different transport regimes\nranging from the far off-resonance to the quasi-resonant regime, and for a wide\nrange of parameters. They show that a non-equilibrium (i.e. bias dependent)\ndynamical (i.e. energy dependent) renormalisation is obtained for the contact\nbetween the left electrode and the central region in the form of a\nnon-equilibrium renormalisation of the lead embedding potential. The\nconductance is affected by the renormalisation of the contact: the amplitude of\nthe main resonance peak is modified as well as `the lineshape of the first\nvibron side-band.",
        "positive": "Coulomb drag at zero temperature: We show that the Coulomb drag effect exhibits saturation at small\ntemperatures, when calculated to the third order in the interlayer\ninteractions. The zero-temperature transresistance is inversely proportional to\nthe third power of the dimensionless sheet conductance. The effect is therefore\nthe strongest in low mobility samples. This behavior should be contrasted with\nthe conventional (second order) prediction that the transresistance scales as a\ncertain power of temperature and is almost mobility-independent. The result\ndemonstrates that the zero-temperature drag is not an unambiguous signature of\na strongly-coupled state in double-layer systems."
    },
    {
        "anchor": "Collective Edge Excitations In The Quantum Hall Regime: Edge Helicons\n  And Landau-level Structure: Based on a microscopic evaluation of the local current density, a treatment\nof edge magnetoplasmons (EMP) is presented for confining potentials that allow\nLandau level (LL) flattening to be neglected. Mode damping due to\nelectron-phonon interaction is evaluated. For nu=1, 2 there exist independent\nmodes spatially symmetric or antisymmetric with respect to the edge. Certain\nmodes, changing shape during propagation, are nearly undamped even for very\nstrong dissipation and are termed edge helicons.\n  For nu > 2 inter-LL Coulomb coupling leads to a strong repulsion of the\ndecoupled LL fundamental modes. The theory agrees well with recent experiments.",
        "positive": "Robust Fabry-Perot interference in dual-gated Bi$_2$Se$_3$ devices: We study Fabry-Perot interference in hybrid devices, each consisting of a\nmesoscopic superconducting disk deposited on the surface of a three-dimensional\ntopological insulator. Such structures are hypothesized to contain protected\nzero modes known as Majorana fermions bound to vortices. The interference\nmanifests as periodic conductance oscillations of magnitude $\\sim 0.1$ $e^2/h$.\nThese oscillations show no strong dependence on bulk carrier density or sample\nthickness, suggesting that they result from phase coherent transport in surface\nstates. However, the Fabry-Perot interference can be tuned by both top and back\ngates, implying strong electrostatic coupling between the top and bottom\nsurfaces of topological insulator."
    },
    {
        "anchor": "Absence versus Presence of Dissipative Quantum Phase Transition in\n  Josephson Junctions: Dissipative quantum phase transition has been widely believed to occur in a\nJosephson junction coupled to a resistor despite a lack of concrete\nexperimental evidence. Here, on the basis of both numerical and analytical\nnonperturbative renormalization group (RG) analyses, we reveal breakdown of\nprevious perturbative arguments and defy the common wisdom that the transition\nalways occurs at the quantum resistance $R_{Q} \\!=\\! h/(4e^2)$. We find that RG\nflows in nonperturbative regimes induce nonmonotonic renormalization of the\ncharging energy and lead to a qualitatively different phase diagram, where the\ninsulator phase is strongly suppressed to the deep charge regime (Cooper pair\nbox), while the system is always superconducting in the transmon regime. We\nidentify a previously overlooked dangerously irrelevant term as an origin of\nthe failure of conventional understandings. Our predictions can be tested in\nrecent experiments realizing high-impedance long superconducting waveguides and\nwould provide a solution to the long-standing controversy about the fate of\ndissipative quantum phase transition in the resistively shunted Josephson\njunction.",
        "positive": "Fermionic Retroreflection, Hole Jets and Magnetic Steering in 2D\n  Electron Systems: Electron interactions are usually probed indirectly, through their impact on\ntransport coefficients. Here we describe a direct scheme that, in principle,\ngives access to the full angle dependence of carrier scattering in 2D Fermi\ngases. The latter is particularly interesting, because, due to the dominant\nrole of head-on collisions, carrier scattering generates tightly focused\nfermionic jets. We predict a jet-dominated signal for the magnetic steering\ngeometry, that appears at classically weak $B$-fields, much lower than the\nfree-particle focusing fields. The effect is \"anti-Lorentz\" in sign, producing\na peak at the field polarity for which the free-particle focusing does not\noccur. The steering signal measured vs. $B$ yields detailed information on the\nangular structure of fermionic jets."
    },
    {
        "anchor": "Energy-dependent resonance broadening in symmetric and asymmetric\n  molecular junctions from an ab initio non-equilibrium Green's function\n  approach: The electronic structure of organic-inorganic interfaces often feature\nresonances originating from discrete molecular orbitals coupled to continuum\nlead states. An example are molecular junctions, individual molecules bridging\nelectrodes, where the shape and peak energy of such resonances dictate junction\nconductance, thermopower, I-V characteristics and related transport properties.\nIn molecular junctions where off-resonance coherent tunneling dominates\ntransport, resonance peaks in the transmission function are often assumed to be\nLorentzian functions with an energy-independent broadening parameter $\\Gamma$.\nHere we define a new energy-dependent resonance broadening function,\n$\\Gamma(E)$, based on diagonalization of non-Hermitian matrices, which can\ndescribe resonances of a more complex, non-Lorentzian nature and can be\ndecomposed into components associated with the left and right lead,\nrespectively. We compute this quantity via an \\emph{ab initio} non-equilibrium\nGreen's function approach based on density functional theory for both symmetric\nand asymmetric molecular junctions, and show that our definition of\n$\\Gamma(E)$, when combined with Breit-Wigner formula, reproduces the\ntransmission calculated from DFT-NEGF. Through a series of examples, we\nillustrate how this approach can shed new light on experiments and\nunderstanding of junction transport properties in terms of molecular orbitals.",
        "positive": "Near-field thermal transistor: Using a block of three separated solid elements, a thermal source and drain\ntogether with a gate made of an insulator-metal transition material exchanging\nnear-field thermal radiation, we introduce a nanoscale analog of a field-effect\ntransistor which is able to control the flow of heat exchanged by evanescent\nthermal photons between two bodies. By changing the gate temperature around its\ncritical value, the heat flux exchanged between the hot body (source) and the\ncold body (drain) can be reversibly switched, amplified, and modulated by a\ntiny action on the gate. Such a device could find important applications in the\ndomain of nanoscale thermal management and it opens up new perspectives\nconcerning the development of contactless thermal circuits intended for\ninformation processing using the photon current rather than the electric\ncurrent."
    },
    {
        "anchor": "Simulation of Higher Dimensional Discrete Time Crystals on a Quantum\n  Computer: The study of topologically ordered states have given rise to a growing\ninterest in symmetry protected states in quantum matter. Recently, this theory\nhas been extended to quantum many body systems which demonstrate ordered states\nat low temperature. An example of this is the discrete time crystal (DTC) which\nhas been demonstrated in a real quantum computer and in driven systems. These\nstates are periodic in time and are protected to disorder to a certain extent.\nIn general, DTC can be classified into two phases, the stable many body\nlocalization (MBL) state, and the disordered thermal state. This work\ndemonstrates by generalizing DTC to 2 dimensions, there is an decrease in\nthermal noise and an increase in the operating range of the MBL range in the\npresence of disorder.",
        "positive": "Nonequilibrium charge dynamics of light-driven rings threaded by a\n  magnetic flux: We study theoretically the charge polarization and the charge current\ndynamics of a mesoscopic ring driven by short asymmetric electromagnetic pulses\nand threaded by an external static magnetic flux. It is shown that the\npulse-induced charge polarization and the associated light-emission is\ncontrollable by tuning the external magnetic flux. Applying two mutually\nperpendicular pulses triggers a charge current in the ring. The interplay\nbetween this nonequilibrium and the persistent currents is investigated and the\nconditions under which the pulses stop the persistent current are identified."
    },
    {
        "anchor": "Anisotropic Raman Scattering and Mobility in Monolayer 1Td-ReS2\n  Controlled by Strain Engineering: Regulation of electronic structure and mobility cut-on rate in\ntwo-dimensional transition metal dichalcogenides (TMDs) has attracted much\nattention because of its potential in electronic device design. The anisotropic\nRaman scattering and mobility cut-on rate of monolayer unique distorted-1T(1Td)\nReS2 with external strain are determined theoretically based on the density\nfunction theory. The angle-dependent Raman spectrum of Ag-like, Eg-like and Cp\nmodels are used to discriminate and analysis structural anisotropy; the strain\nis exploited to adjust the structural symmetry and electronic structure of ReS2\nso as to enhance mobility cut-on rate to almost 6 times of the original value.\nOur results suggest the use of the strain engineering in high-quality\nsemiconductor switch device.",
        "positive": "Magnetoresistance and negative differential resistance in Ni/Graphene/Ni\n  vertical heterostructures driven by finite bias voltage: A first-principles\n  study: Using the nonequilibrium Green function formalism combined with density\nfunctional theory, we study finite-bias quantum transport in Ni/Gr_n/Ni\nvertical heterostructures where $n$ graphene layers are sandwiched between two\nsemi-infinite Ni(111) electrodes. We find that recently predicted \"pessimistic\"\nmagnetoresistance of 100% for $n \\ge 5$ junctions at zero bias voltage $V_b\n\\rightarrow 0$, persists up to $V_b \\simeq 0.4$ V, which makes such devices\npromising for spin-torque-based device applications. In addition, for parallel\norientations of the Ni magnetizations, the $n=5$ junction exhibits a pronounced\nnegative differential resistance as the bias voltage is increased from $V_b=0$\nV to $V_b \\simeq 0.5$ V. We confirm that both of these nonequilibrium effects\nhold for different types of bonding of Gr on the Ni(111) surface while\nmaintaining Bernal stacking between individual Gr layers."
    },
    {
        "anchor": "Balanced Quantum Hall Resistor: The quantum anomalous Hall effect in magnetic topological insulators has been\nrecognized as a promising platform for applications in quantum metrology. The\nprimary reason for this is the electronic conductance quantization at zero\nexternal magnetic field, which allows to combine it with the quantum standard\nof voltage. Here we demonstrate a measurement scheme that increases the\nrobustness of the zero magnetic field quantum anomalous Hall resistor, allowing\nfor higher operational currents. This is achieved by simultaneous current\ninjection into the two disconnected perimeters of a multi-terminal Corbino\ndevice to balance the electrochemical potential between the edges, screening\nthe electric field that drives back-scattering through the bulk, and thus\nimproving the stability of the quantization at increased currents. This\napproach is not only applicable to devices based on the quantum anomalous Hall\neffect, but more generally can also be applied to existing quantum resistance\nstandards that rely on the integer quantum Hall effect.",
        "positive": "Phenalenyls as tunable excellent molecular conductors and switchable\n  spin filters: We demonstrate a new class of molecules for exceptional performance in\nmolecular electronics and spintronics. Phenalenyl-based radicals are stable\nradicals whose electronic properties can be tuned readily by heteroatom\nsubstitution. We employ density functional theory-based non-equilibrium Green's\nfunction (NEGF-DFT) calculations to show that this class of molecules exhibits\ntunable spin- and charge-transport properties in single molecule junctions. Our\nsimulations identify the design principles and interplay between unusually high\nconductivity and strong spin-filtering: Paired with moderate conductance\n($10^{-3} G_0$), two of the four radicals investigated exhibit above 80% spin\nfilter efficiency that is moreover tunable via bias control. Conversely, two\nradicals that make modest spin filters are excellent conductors with a low bias\nconductance reaching $0.48 G_0$. This is made possible by the unusually good\nalignment of the singly occupied or unoccupied molecular orbital with the Fermi\nlevel of the electrodes, overcoming the limitations of Fermi level pinning that\ntypically plague molecular electronics. We show that this interplay between\nexcellent conductance and high spin-filter efficiency is determined by the\nenergy alignment between the singly (un)occupied molecular orbital and the\nFermi level of the electrodes, and that for phenalenyls this can be readily\ncontrolled with judicious heteroatom substitution."
    },
    {
        "anchor": "Chiral Pinwheel Heterojunctions Self Assembled from C60 and Pentacene: We demonstrate the self-assembly of C$_{60}$ and pentacene (Pn) molecules\ninto acceptor-donor heterostructures which are well-ordered and -- despite the\nhigh degree of symmetry of the constituent molecules -- {\\it chiral}. Pn was\ndeposited on Cu(111) to monolayer coverage, producing the random-tiling ($R$)\nphase as previously described. Atop $R$-phase Pn, post-deposited C$_{60}$\nmolecules cause rearrangement of the Pn molecules into domains based on chiral\nsupramolecular `pinwheels'. These two molecules are the highest-symmetry\nachiral molecules so far observed to coalesce into chiral heterostructures.\nAlso, the chiral pinwheels (composed of 1 C$_{60}$ and 6 Pn each) may share Pn\nmolecules in different ways to produce structures with different lattice\nparameters and degree of chirality. High-resolution scanning tunneling\nmicroscopy (STM) results and knowledge of adsorption sites allow the\ndetermination of these structures to a high degree of confidence. The\nmeasurement of chiral angles identical to those predicted is a further\ndemonstration of the accuracy of the models. Van der Waals density functional\ntheory calculations reveal that the Pn molecules around each C$_{60}$ are\ntorsionally flexed around their long molecular axes and that there is charge\ntransfer from C$_{60}$ to Pn in each pinwheel.",
        "positive": "Demonstration of one-parameter scaling at the Dirac point in graphene: We numerically calculate the conductivity $\\sigma$ of an undoped graphene\nsheet (size $L$) in the limit of vanishingly small lattice constant. We\ndemonstrate one-parameter scaling for random impurity scattering and determine\nthe scaling function $\\beta(\\sigma)=d\\ln\\sigma/d\\ln L$. Contrary to a recent\nprediction, the scaling flow has no fixed point ($\\beta>0$) for conductivities\nup to and beyond the symplectic metal-insulator transition. Instead, the data\nsupports an alternative scaling flow for which the conductivity at the Dirac\npoint increases logarithmically with sample size in the absence of intervalley\nscattering -- without reaching a scale-invariant limit."
    },
    {
        "anchor": "Comment on \"Magnetic Relaxations of Antiferromagnetic Nanoparticles in\n  Magnetic Fields\": We have carried out in ferritin the Field-Cooling method and data analysis\nproposed by Mamiya et al. (Phys. Rev. Lett. 88, 67202 (2002) at T = 5 K in\norder to check the time magnetic relaxation of these antiferromagnetic\nnanoparticles as a function of the magnetic field. We found that relaxation at\nT = 5 K in ferritin is faster in the absence of magnetic field, in good\nagreement with the zero-field Resonant Spin Quantum Tunneling observed\npreviously in ferritin (Phys. Rev. Lett. 79, 1754 (1997).",
        "positive": "Theory of the plasma-wave photoresponse of a gated graphene sheet: The photoresponse of graphene has recently received considerable attention.\nThe main mechanisms yielding a finite dc response to an oscillating radiation\nfield which have been investigated include responses of photovoltaic,\nphoto-thermoelectric, and bolometric origin. In this Article we present a fully\nanalytical theory of a photoresponse mechanism which is based on the excitation\nof plasma waves in a gated graphene sheet. By employing the theory of\nrelativistic hydrodynamics, we demonstrate that plasma-wave photodetection is\nsubstantially influenced by the massless Dirac fermion character of carriers in\ngraphene and that the efficiency of photodetection can be improved with respect\nto that of ordinary parabolic-band electron fluids in semiconductor\nheterostructures."
    },
    {
        "anchor": "Error correction for gate operations in systems of exchange-coupled\n  singlet-triplet qubits in double quantum dots: We present a scheme for correcting for crosstalk- and noise-induced errors in\nexchange-coupled singlet-triplet semiconductor double quantum dot qubits. While\nexchange coupling allows the coupling strength to be controlled independently\nof the intraqubit exchange couplings, there is also the problem of leakage,\nwhich must be addressed. We show that, if a large magnetic field difference is\npresent between the two qubits, leakage is suppressed. We then develop pulse\nsequences that correct for crosstalk- and noise-induced errors and present\nparameters describing them for the 24 Clifford gates. We determine the\ninfidelity for both the uncorrected and corrected gates as a function of the\nerror-inducing terms and show that our corrected pulse sequences reduce the\nerror by several orders of magnitude.",
        "positive": "Negative Differential Resistance and Astability of the Wigner Solid: We report an unusual breakdown of the magnetically induced Wigner solid in an\nexceptional two-dimensional electron gas. The current-voltage characteristic is\nfound to be hysteretic in the voltage biased setup and has a region of negative\ndifferential resistance in the current biased setup. When the sample is current\nbiased in the region of negative differential resistance, the voltage on and\nthe current through the sample develop spontaneous narrow band oscillations."
    },
    {
        "anchor": "Distribution of Persistent Currents in a Multi-Arm Mesoscopic Ring: We propose an idea to investigate persistent current in individual arms of a\nmulti-arm mesoscopic ring. Following a brief description of persistent current\nin a traditional Aharonov-Bohm (AB) ring, we examine the behavior of persistent\ncurrents in separate arms of a three-arm mesoscopic ring. Our analysis may be\nhelpful in studying magnetic response of any complicated quantum network.",
        "positive": "Gap plasmonics of silver nanocube dimers: We theoretically investigate gap plasmons for two silver nanocubes coupled\nthrough a molecular tunnel junction. In absence of tunneling, the red-shift of\nthe bonding mode saturates with decreasing gap distance. Tunneling at small gap\ndistances leads to a damping and slight blue-shift of the bonding mode, but no\nlow-energy charge transfer plasmon mode appears in the spectra. This finding is\nin stark contrast to recent work of Tan et al. [Science 343, 1496 (2014)]."
    },
    {
        "anchor": "Electron Scattering and Hybrid Phonons in Low Dimensional Laser\n  Structures made with GaAs/AlxGa1-xAs: We theoretically and numerically present the hybrid phonon modes for the\ndouble heterostructure GaAs/AlxGa1-xAs and their interactions with electrons.\nMore specifically, we have calculated the electron capture within a symmetric\nquantum well via the emission of hybrid phonons. Our investigation shows that\nthe capture rates via the hybrid phonons are matched to the rates predicted by\nthe dielectric continuum (DC) model and the concentration of aluminium which is\nan important parameter for controlling the electron capture process in light\nemitting diodes (LED).",
        "positive": "Thermal motion of skyrmion arrays in granular films: Magnetic skyrmions are topologically-distinct swirls of magnetic moments\nwhich display particle-like behaviour, including the ability to undergo\nthermally-driven diffusion. In this paper we study the thermally activated\nmotion of arrays of skyrmions using temperature dependent micromagnetic\nsimulations where the skyrmions form spontaneously. In particular, we study the\ninteraction of skyrmions with grain boundaries, which are a typical feature of\nsputtered ultrathin films used in experimental devices. We find the\ninteractions lead to two distinct regimes. For longer lag times the grains lead\nto a reduction in the diffusion coefficient, which is strongest for grain sizes\nsimilar to the skyrmion diameter. At shorter lag times the presence of grains\nenhances the effective diffusion coefficient due to the gyrotropic motion of\nthe skyrmions induced by their interactions with grain boundaries. For grain\nsizes significantly larger than the skyrmion diameter clustering of the\nskyrmions occurs in grains with lower magnetic anisotropy."
    },
    {
        "anchor": "The effect of oscillating Fermi energy on the line shape of the\n  Shubnikov-de Haas oscillation in a two dimensional electron gas: The line shape of the Shubnikov-de Haas (SdH) oscillation has been analyzed\nin detail for a GaAs/AlGaAs two-dimensional electron gas. The line shape, or\nequivalently the behavior of the Fourier components, of the experimentally\nobserved SdH oscillation is well reproduced by the sinusoidal density of states\nat the Fermi energy that oscillates with a magnetic field in a saw-tooth shape\nto keep the electron density constant. This suggests that the broadening of\neach Landau level by disorder is better described by a Gaussian than by a\nLorentzian.",
        "positive": "2D-3D crossover in a dense electron liquid in silicon: Doping of silicon via phosphene exposures alternating with molecular beam\nepitaxy overgrowth is a path to Si:P substrates for conventional\nmicroelectronics and quantum information technologies. The technique also\nprovides a new and well-controlled material for systematic studies of\ntwo-dimensional lattices with a half-filled band. We show here that for a dense\n($n_s=2.8\\times 10^{14}$\\,cm$^{-2}$) disordered two-dimensional array of P\natoms, the full field angle-dependent magnetostransport is remarkably well\ndescribed by classic weak localization theory with no corrections due to\ninteraction effects. The two- to three-dimensional cross-over seen upon warming\ncan also be interpreted using scaling concepts, developed for anistropic\nthree-dimensional materials, which work remarkably except when the applied\nfields are nearly parallel to the conducting planes."
    },
    {
        "anchor": "Continuous-wave versus time-resolved measurements of Purcell-factors for\n  quantum dots in semiconductor microcavities: The light emission rate of a single quantum dot can be drastically enhanced\nby embedding it in a resonant semiconductor microcavity. This phenomenon is\nknown as the Purcell effect, and the coupling strength between emitter and\ncavity can be quantified by the Purcell factor. The most natural way for\nprobing the Purcell effect is a time-resolved measurement. However, this\napproach is not always the most convenient one, and alternative approaches\nbased on a continuous-wave measurement are often more appropriate. Various\nsignatures of the Purcell effect can indeed be observed using continuous-wave\nmeasurements (increase of the pump rate needed to saturate the quantum dot\nemission, enhancement of its emission rate at saturation, change of its\nradiation pattern), signatures which are encountered when a quantum dot is put\non-resonance with the cavity mode. All these observations potentially allow one\nto estimate the Purcell factor. In this paper, we carry out these different\ntypes of measurements for a single quantum dot in a pillar microcavity and we\ncompare their reliability. We include in the data analysis the presence of\nindependent, non-resonant emitters in the microcavity environment, which are\nresponsible for a part of the observed fluorescence.",
        "positive": "Dynamical generation and detection of entanglement in neutral leviton\n  pairs: The entanglement of coherently split electron-hole pairs in an electronic\nconductor is typically not considered accessible due to particle number\nconservation and fermionic super-selection rules. We demonstrate here that\ncurrent cross-correlation measurements at the outputs of an electronic\nMach-Zehnder interferometer can nevertheless provide a robust witness of\nelectron-hole entanglement. Specifically, we consider neutral excitations\ngenerated by modulating the transmission of an unbiased quantum point contact\nperiodically in time. For an optimized modulation profile, an entangled state\nwith one positively-charged leviton (a hole) and one negatively-charged leviton\n(an electron) gets delocalized over the two paths of the interferometer and is\ndetected at the output arms. We evaluate the influence of finite electronic\ntemperatures and dephasing corresponding to recent experiments."
    },
    {
        "anchor": "Influence of Metal-Graphene Contact on the Operation and Scalability of\n  Graphene Field-Effect-Transistors: We explore the effects of metal contacts on the operation and scalability of\n2D Graphene Field-Effect-Transistors (GFETs) using detailed numerical device\nsimulations based on the non-equilibrium Green's function formalism\nself-consistently solved with the Poisson equation at the ballistic limit. Our\ntreatment of metal-graphene (M-G) contacts captures: (1) the doping effect due\nto the shift of the Fermi level in graphene contacts, (2) the density-of-states\n(DOS) broadening effect inside graphene contacts due to Metal-Induced-States\n(MIS). Our results confirm the asymmetric transfer characteristics in GFETs due\nto the doping effect by metal contacts. Furthermore, at higher M-G coupling\nstrengths the contact DOS broadening effect increases the on-current, while the\nimpact on the minimum current (Imin) in the off-state depends on the source to\ndrain bias voltage and the work-function difference between graphene and the\ncontact metal. Interestingly, with scaling of the channel length, the MIS\ninside the channel has a weak influence on Imin even at large M-G coupling\nstrengths, while direct source-to-drain (S -> D) tunneling has a stronger\ninfluence. Therefore, channel length scalability of GFETs with sufficient gate\ncontrol will be mainly limited by direct S -> D tunneling, and not by the MIS.",
        "positive": "Effects of scattering area shape on spin conductance in a four-terminal\n  spin-Hall setup: We study spin conductance in a ballistic and quasi-ballistic two dimensional\nelectron system with Rasbha spin-orbit coupling. The system has a four-terminal\ngeometry with round corners at the connection to the leads. It is found that by\ngoing from sharp corners to more round corners in the ballistic system the\nenergy depended spin conductance goes from being relatively flat to a curve\nshowing a series of minima and maxima. It is also found that when changing the\nsize of the terminal area by modifying the roundness of the terminal corners\nthe maxima and minima in the transverse spin conductance are shifted in energy.\nThis shift is due increased (decreased) energy for smaller (larger) terminal\narea. These results were also found to be reasonably stable in quasi-ballistic\nsystems."
    },
    {
        "anchor": "Single-electron heat diode: We introduce a new functional nanoscale device, a single-electron heat diode,\nconsisting of two quantum dots or metallic islands coupled to electronic\nreservoirs by tunnel contacts. Electron transport through the system is\nforbidden but the capacitive coupling between the two dots allows electronic\nfluctuations to transmit heat between the reservoirs. When the reservoir\ntemperatures are biased in the forward direction, heat flow is enabled by a\nfour-step sequential tunneling cycle, while in the reverse-biased configuration\nthis process is suppressed due to Coulomb blockade effects. In an optimal setup\nthe leakage heat current in the reverse direction is only a few percent of the\nforward current.",
        "positive": "Interaction-Induced Enhancement of Spin-Orbit Coupling in\n  Two-Dimensional Electronic System: We study theoretically the renormalization of the spin-orbit coupling\nconstant of two-dimensional electrons by electron-electron interactions. We\ndemonstrate that, similarly to the $g$ factor, the renormalization corresponds\nto the enhancement, although the magnitude of the enhancement is weaker than\nthat for the $g$ factor. For high electron concentrations (small interaction\nparameter $r_s$) the enhancement factor is evaluated analytically within the\nstatic random phase approximation. For large $r_s\\sim 10$ we use an approximate\nexpression for effective electron-electron interaction, which takes into\naccount the local field factor, and calculate the enhancement numerically. We\nalso study the interplay between the interaction-enhanced Zeeman splitting and\ninteraction-enhanced spin-orbit coupling."
    },
    {
        "anchor": "Transversal magnetoresistance and Shubnikov-de Haas oscillations in Weyl\n  semimetals: We explore theoretically the magnetoresistance of Weyl semimetals in\ntransversal magnetic fields away from charge neutrality. The analysis within\nthe self-consistent Born approximation is done for the two different models of\ndisorder: (i) short-range impurties and (ii) charged (Coulomb) impurities. For\nthese models of disorder, we calculate the conductivity away from charge\nneutrality point as well as the Hall conductivity, and analyze the transversal\nmagnetoresistance (TMR) and Shubnikov-de Haas oscillations for both types of\ndisorder. We further consider a model with Weyl nodes shifted in energy with\nrespect to each other (as found in various materials) with the chemical\npotential corresponding to the total charge neutrality. In the experimentally\nmost relevant case of Coulomb impurities, we find in this model a large TMR in\na broad range of quantizing magnetic fields. More specifically, in the\nultra-quantum limit, where only the zeroth Landau level is effective, the TMR\nis linear in magnetic field. In the regime of moderate (but still quantizing)\nmagnetic fields, where the higher Landau levels are relevant, the rapidly\ngrowing TMR is supplemented by strong Shubnikov-de Haas oscillations,\nconsistent with experimental observations.",
        "positive": "Transient Oscillation of Currents in Quantum Hall Effect of Bloch\n  Electrons: We consider the quantum Hall effect of two-dimensional electrons with a\nperiodic potential and study the time dependence of the Hall and longitudinal\ncurrents when the electric field is applied abruptly. We find that the currents\noscillate in time with very large frequencies because of quantum fluctuation\nand the oscillations eventually vanish, for their amplitudes decay as 1/t."
    },
    {
        "anchor": "Manifestation of the Berry connection in chiral lattice systems: The Aharonov-Bohm effect is a physical phenomenon where the vector potential\ninduces a phase shift of electron wavepackets in regions with zero magnetic\nfields. It is often referred to as evidence for the physical reality of the\nvector potential. A similar effect can be observed in solid-state systems,\nwhere the Berry connection can influence electron dynamics. Here, we show that\nin chiral-symmetric processes the Berry connection determines an observable\neffect on the mean chiral displacement of delocalized wavefunctions. This\nfinding is supported by a photonic experiment realizing a topological quantum\nwalk, and demonstrates a new effect that can be attributed directly to the\npresence of a gauge field.",
        "positive": "Minimal model for higher-order topological insulators and phosphorene: A higher order topological insulator is an extended notion of the\nconventional topological insulator, which belongs to a special class of\ntopological insulators where the conventional bulk-boundary correspondence is\nnot applicable. The bulk topological index may be described by the Wannier\ncenter located at a high symmetry point of the crystal. In this paper we\npropose minimal models for the second-order topological insulator in two\ndimensions and the third-order topological insulator in three dimensions. They\nare anisotropic two-band models with two different hopping parameters. The\ntwo-dimensional model is known to capture the essential physics of phosphorene\nnear the Fermi level. It has so far been recognized as a trivial insulator due\nto the absence of topological edge states in nanoribbons. However, we\ndemonstrate the emergence of topological boundary states in zero dimension,\ni.e., in nanodisks. In particular, the diamond structure exhibits such\ntopological states at two corners, each of which carries a 1/2 fractional\ncharge. We predict that these corner states will be observed in the diamond\nstructure of phosphorene."
    },
    {
        "anchor": "Low temperature magnetoresistance of (111)\n  (La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)/SrTiO$_3$: The two dimensional conducting interfaces in SrTiO$_3$-based systems are\nknown to show a variety of coexisting and competing phenomena in a complex\nphase space. Magnetoresistance measurements, which are typically used to\nextract information about the various interactions in these systems, must be\ninterpreted with care, since multiple interactions can contribute to the\nresistivity in a given range of magnetic field and temperature. Here we review\nall the phenomena that can contribute to transport in SrTiO$_3$-based\nconducting interfaces at low temperatures, and discuss possible ways to\ndistinguish between various phenomena. We apply this analysis to the\nmagnetoresistance data of (111) oriented\n(La$_{0.3}$Sr$_{0.7}$)(Al$_{0.65}$Ta$_{0.35}$)/STO (LSAT/STO) heterostructures\nin perpendicular field, and find an excess negative magnetoresistance\ncontribution which cannot be explained by weak localization alone. We argue\nthat contributions from magnetic scattering as well as electron-electron\ninteractions can provide a possible explanation for the observed\nmagnetoresistance.",
        "positive": "Thermal and Electrical Properties of Multiwall Carbon Nanotubes: In this dissertation, thermal and electrical properties of aligned multiwall\ncarbon nanotubes (MWNTs) prepared by thermal decomposition of hydrocarbons have\nbeen experimentally studied. The thesis consists of six chapters. Ch1 is an\nintroduction. In Ch2, sample preparation and characterizations are described.\nIn Ch3, by using a self-heating 3-Omega method, the specific heat, thermal\ndiffusivity and thermal conductivity of MWNTs are measured. MWNTs of 20-40 nm\ndiameter show a linear specific heat over a temperature range of 10-300 K,\nsuggesting that inter-wall coupling in MWNTs is rather weak compared with that\nof graphite. The thermal conductivity shows a crossover from linear temperature\ndependence to a square law at ~120K, with a rather low room-temperature\namplitude which may have resulted from structural defects. In Ch4, four-wire\ntunneling spectroscopy of junctions between MWNTs and a normal metal is\nmeasured. The Coulomb interactions in the MWNTs give rise to a strong zero-bias\nsuppression of tunneling density of states that can be fitted numerically with\nthe environmental quantum-fluctuation theory. At low temperatures, an\nasymmetric conductance anomaly near zero bias is observed, which is interpreted\nas Fano resonance in the strong tunneling regime. In Ch5, the thermoelectric\npower (TEP) and longitudinal magnetoresistance (MR) of MWNTs are measured. A\nmoderate positive TEP with metallic-like linear temperature dependence is\nfound, suggesting that the electron-hole symmetry in metallic MWNTs is broken.\nPeriodic oscillations in MR are observed at 20 mK when a longitudinal magnetic\nfield is applied. The period of oscillation agrees well with the period h/2e of\nAltshuler-Aronov-Spivak (AAS) effect if only the outermost graphene wall\ncontributes to conductance, clearly indicating quantum-interference effects at\nlow temperatures. Ch6 presents the main conclusions."
    },
    {
        "anchor": "Weak localization in boron nitride encapsulated bilayer MoS$_2$: We present measurements of weak localization on hexagonal boron nitride\nencapsulated bilayer MoS$_2$. From the analysis we obtain information regarding\nthe phase-coherence and the spin diffusion of the electrons. We find that the\nencapsulation with boron nitride provides higher mobilities in the samples, and\nthe phase-coherence shows improvement, while the spin relaxation does not\nexhibit any significant enhancement compared to non-encapsulated MoS$_2$. The\nspin relaxation time is in the order of a few picoseconds, indicating a fast\nintravalley spin-flip rate. Lastly, the spin-flip rate is found to be\nindependent from electron density in the current range, which can be explained\nthrough counteracting spin-flip scattering processes based on electron-electron\nCoulomb scattering and extrinsic Bychkov-Rashba spin-orbit coupling.",
        "positive": "Nonequilibrium electron charging in carbon-nanotube-based molecular\n  bridges: We evidence the importance of electron charging under nonequilibrium\nconditions for carbon-nanotube-based molecular bridges, using a self-consistent\nGreen's function method with an extended Huckel Hamiltonian and a\nthree-dimensional Poisson solver. Our analysis demonstrates that such feature\nis highly dependent on the chirality of the carbon nanotube as well as on the\ntype of the contact metal, conditioning in a nongeneralized way the system's\nconduction mechanism. Based on its impact on transport, we argue that\nself-consistency is essential for the current-voltage calculations of\nsemiconducting nanotubes, whereas less significant in the case of metallic\nones."
    },
    {
        "anchor": "Controlling energy transfer time between two coupled magnetic\n  vortex-state disks: The influence of the in-plane uniaxial anisotropy (IPUA) in the mutual energy\ntransfer time ($\\tau$) between two identical coupled nanodisks was studied.\nUsing an analytical dipolar model we obtained the interactions between the\ndisks along x and y directions (the coupling integrals) as a function of the\nuniaxial anisotropy constant (K$_{\\sigma}$) and the distance. We find that the\nIPUA increases the interaction between the disks allowing shorter energy\ntransfer times. For our range of K$_{\\sigma}$ values we get a drop in the\nvalues of $\\tau$ of up to about 70$\\%$. From the lagrangian of the system we\nobtained the equations of motion and the coupling frequencies of the dynamic\nsystem as a function of distance and K$_{\\sigma}$. The coupling frequencies\nwere also obtained from micromagnetic simulations. Our results of the\nsimulations are in agreement with the analytical results.",
        "positive": "Carbon doped symmetric GaAs/AlGaAs quantum wells with hole mobilities\n  beyond 10^6 cm^2/Vs: Utilizing a novel carbon doping source, we prepared two-dimensional hole\ngases in a symmetric quantum well structure in the GaAs/AlGaAs heterosystem.\nLow temperature hole mobilities up to 1.2 x 10^6 cm^2/Vs at a density of 2.3 x\n10^11 cm^-2 were achieved on GaAs (001) substrates. In contrast to electron\nsystems, the hole mobility sensitively depends on variations of the quantum\nwell width and the spacer thickness. In particular an increase of the quantum\nwell width from an optimal value of 15 nm to 18 nm is accompanied by a 35 %\nreduction of the hole mobility. The quality of ultrahigh-mobility electron\nsystems is not affected by the employed carbon doping source."
    },
    {
        "anchor": "Monte Carlo Evaluation of Non-Abelian Statistics: We develop a general framework to (numerically) study adiabatic braiding of\nquasiholes in fractional quantum Hall systems. Specifically, we investigate the\nMoore-Read (MR) state at $\\nu=1/2$ filling factor, a known candidate for\nnon-Abelian statistics, which appears to actually occur in nature. The\nnon-Abelian statistics of MR quasiholes is demonstrated explicitly for the\nfirst time, confirming the results predicted by conformal field theories.",
        "positive": "Negative GMR Effect in current perpendicular-to-plane (Zn,Cr)Te/Cu/Co\n  spin salves: Magnetic and transport properties are explored in the current\nperpendicular-to-plane (CPP) spin salves with Cr doped wide band gap\nsemiconductor ZnTe as one of the ferromagnetic electrodes. A negative\nmagnetoresistance is observed in these CPP spin valves at low temperature, with\na strong temperature dependence. This effect can be explained by the large\ndifference of spin scattering asymmetry coefficients in (Zn,Cr)Te and Cobalt,\ndue to the very different spin polarizations of the two materials as revealed\nby the DFT calculation."
    },
    {
        "anchor": "Thermally-induced spin polarization of a two dimensional electron gas: Spin polarization of a two-dimensional electron gas with Rashba spin-orbit\ninteraction, induced by a thermo-current, is considered theoretically. It is\nshown that a temperature gradient gives rise to an in-plane spin polarization\nof the electron gas, which is normal to the temperature gradient. The\nlow-temperature spin polarization changes sign when the Fermi level crosses\nbottom edge of the upper electronic subband. We also compare the results with\nspin polarization induced by an external electric field (current).",
        "positive": "Reinterpretation of Hall effect in medium with hole: We reinterpret the distribution of the Hall potential in the Hall\nbar-with-a-hole that has been found and interpreted by Mani and Klitzing [Appl.\nPhys. Lett., 64 1262 (1994)]. Our reinterpretation explains all the \"paradoxes\"\nwithout resorting to new theoretical conceptions."
    },
    {
        "anchor": "Superconducting Quantum Point Contacts: We review our experiments on the electronic transport properties of atomic\ncontacts between metallic electrodes, in particular superconducting ones.\nDespite ignorance of the exact atomic configuration, these ultimate quantum\npoint contacts can be manipulated and well characterized in-situ. They allow\nperforming fundamental tests of the scattering theory of quantum transport. In\nparticular, we discuss the case of the Josephson effect.",
        "positive": "Size and shape of skyrmions for variable Dzyaloshinskii-Moriya\n  interaction and uniaxial anisotropy: We have performed micromagnetic simulations to study the formation of\nskyrmions in ferromagnetic elements with different shapes having perpendicular\nanisotropy. The strength of Dzyaloshinskii-Moriya interaction (D) and uniaxial\nanisotropy (K) are varied to elucidate the regime in which skyrmion formation\ncan take place. It is found that for a certain combination of D and K skyrmion\nformation does not happen. Further we also observed that for large D and small\nK values, finite size effect dominates which in turn hinders formation of\ntypical N'eel (spherical) skyrmions. However the resulting magnetic phase is\nskyrmionic in nature and has different shape. We also have found that the shape\nof the magnetic nano element has a significant role in determining the final\nmagnetic state in addition to the competing D and K values."
    },
    {
        "anchor": "Electrically Tunable Energy Bandgap in Dual-Gated Ultra-Thin Black\n  Phosphorus Field Effect Transistors: The energy bandgap is an intrinsic character of semiconductors, which largely\ndetermines their properties. The ability to continuously and reversibly tune\nthe bandgap of a single device during real time operation is of great\nimportance not only to device physics but also to technological applications.\nHere we demonstrate a widely tunable bandgap of few-layer black phosphorus (BP)\nby the application of vertical electric field in dual-gated BP field-effect\ntransistors. A total bandgap reduction of 124 meV is observed when the\nelectrical displacement field is increased from 0.10V/nm to 0.83V/nm. Our\nresults suggest appealing potential for few-layer BP as a tunable bandgap\nmaterial in infrared optoelectronics, thermoelectric power generation and\nthermal imaging.",
        "positive": "Coherence and Stimulated Emission in the Tavis-Cummings Model: A Quantum\n  Description of the Free Induction Signal and Radiation Damping in Magnetic\n  Resonance: We numerically solve the Liouville equation for the Tavis Cummings model of\nmultiple spins coupled to a lossless single mode cavity, starting from an\ninitial condition with small numbers of fully polarized spins tipped by a\nspecified angle, and the cavity in its ground Fock state. Time evolution of the\nmagnetizations and cavity states, following small to medium nutation by a\nclassical field, yields a microscopic quantum mechanical picture of radiation\ndamping in magnetic resonance, and the formation of the free induction signal,\nthat is, the transfer of Zeeman energy, via spin coherence, to cavity\ncoherence. Although the motion of the Bloch vector is nonclassical, our quantum\ndescription is related to the macroscopic picture of NMR reception, by showing\nthe close relationship between the usual radiation damping constant, and the\nquantum mechanical Rabi nutation frequency (as enhanced by cavity coupling and\nstimulated emission.) That is, each is the product, of a nutation rate per\noscillator current, and a current. Although the current in the damping constant\nis explicitly limited by cavity losses, which do not enter the formula for the\nRabi frequency, we nonetheless show (in an appendix) how these losses can be\nintroduced into our problem by means of a master equation. Numerical solution\nof the classical Bloch-Kirchhoff equations reinforces the conclusion that the\nstrength of the free induction"
    },
    {
        "anchor": "Topological Boundary Modes from Translational Deformations: Localized states universally appear when a periodic potential is perturbed by\ndefects or terminated at its surface. In this Letter, we theoretically and\nexperimentally demonstrate a mechanism that generates localized states through\ncontinuous translational deformations of periodic potentials. We provide a\nrigorous proof of the emergence of the localized states under the deformations.\nThe mechanism is experimentally verified in microwave photonic crystals. We\nalso demonstrate topological phase windings of reflected waves for translated\nphotonic crystals.",
        "positive": "Twisted bi-layer graphene: microscopic rainbows: Twisted bi-layer graphene (tBLG) has recently attracted interest due to the\npeculiar electrical properties that arise from its random rotational\nconfigurations. Our experiments on CVD-grown graphene from Cu foil and\ntransferred onto Si substrates, with an oxide layer of 100 nm, reveal\nnaturally-produced bi-layer graphene patches which present different\ncolorations when shined with white light. In particular yellow-, pink- and\nblue- colored areas are evidenced. Combining optical microscopy, Raman\nspectroscopy and transmission electron microscopy we have been able to assign\nthese colorations to ranges of rotational angles between the two graphene\nlayers. Optical contrast simulations have been carried out, proving that the\nobservation of the different colorations is due to the angle-dependent\nelectronic properties of tBLG combined with the reflection that results from\nthe layered structure tBLG / 100 nm-thick SiO2 / Si. Our results could lead the\nway to an easy selective identification of bi-layer graphene merely through the\nobservation on an optical microscope."
    },
    {
        "anchor": "Luminescence and absorption in short period superlattices: This paper applies analytical approximations for the luminescence of short\nperiod semiconductor superlattices and analyses the low density regime,\ndemonstrating that the theory clearly connects with low density absorption with\nratios of oscillator strengths of bound and continuum states as expected from\nthe Elliott formula. A numerical study illustrates in detail the bleaching of\nhigher order bound state. The analytical expressions have potential for\nsystematic studies of controlled excitonic pathways characterized by THz\nresponses.",
        "positive": "Coulomb blockade in a non-thermalized quantum dot: We investigate non-equilibrium transport properties of a quantum dot in the\nCoulomb blockade regime under the condition of negligible inelastic scattering\nduring the dwelling time of the electrons in the dot. Using the quantum kinetic\nequation we show that the absence of thermalization leads to a double-step in\nthe distribution function of electrons on the dot, provided that it is\nsymmetrically coupled to the leads. This drastically changes nonlinear\ntransport through the dot resulting in an additional (compared to the\nthermalized case) jump in the conductance at voltages close to the charging\nenergy, which could serve as an experimental manifestation of the absence of\nthermalization."
    },
    {
        "anchor": "Landau level spectroscopy of surface states in the topological insulator\n  Bi$_{0.91}$Sb$_{0.09}$ via magneto-optics: We have performed broad-band zero-field and magneto-infrared spectroscopy of\nthe three dimensional topological insulator Bi$_{0.91}$Sb$_{0.09}$. The\nzero-field results allow us to measure the value of the direct band gap between\nthe conducting $L_a$ and valence $L_s$ bands. Under applied field in the\nFaraday geometry (\\emph{k} $||$ \\emph{H} $||$ C1), we measured the presence of\na multitude of Landau level (LL) transitions, all with frequency dependence\n$\\omega \\propto \\sqrt{H}$. We discuss the ramification of this observation for\nthe surface and bulk properties of topological insulators.",
        "positive": "Electron energy-loss spectroscopy of quasi-two-dimensional crystals:\n  Beyond the energy-loss functions formalism: A consistent theory of electron energy-loss spectroscopy (EELS) includes two\nindispensable elements: (i) electronic response of the target system and (ii)\nquantum kinematics of probing electrons. While for the bulk materials and their\nsurfaces separating these two aspects and focusing on the former is the usual\nsatisfactory practice (the energy-loss functions formalism), we show that, for\nquasi-2D crystals, the interplay of the system's electronic response and the\ndetails of the probe's motion affects EEL spectra dramatically, and it must be\ntaken into account for the reliable interpretation of the experiment. To this\nend, we come up with a unified theory which, on the same footing, treats both\nthe long- and short-range scattering, within both the transmission and\nreflection experimental setups. Our calculations performed for graphene reveal\na phenomenon of a strong coupling between the $\\pi+\\sigma$ plasmon excitation\nand elastic {\\it scattering resonances}. Freed from the conventions of the\nenergy-loss functions formalism, our theory serves as a consistent and\nsystematic means of the understanding of the EELS of quasi-2D materials."
    },
    {
        "anchor": "Electron transport in disordered graphene: We study electron transport properties of a monoatomic graphite layer\n(graphene) with different types of disorder. We show that the transport\nproperties of the system depend strongly on the character of disorder. Away\nfrom half filling, the concentration dependence of conductivity is linear in\nthe case of strong scatterers, in line with recent experimental observations,\nand logarithmic for weak scatterers. At half filling the conductivity is of the\norder of e^2/h if the randomness preserves one of the chiral symmetries of the\nclean Hamiltonian; otherwise, the conductivity is strongly affected by\nlocalization effects.",
        "positive": "Spin-dependent hole quantum transport in Aharonov-Bohm ring structure:\n  possible schemes for spin filter: We study the Aharonov-Bohm (AB) effect in two-dimensional mesoscopic frame in\nhole systems. We show that differing from the AB effect in electron systems,\ndue to the presence of both the heavy hole and the light hole, the conductances\nnot only show the normal spin-unresolved AB oscillations, but also become\nspin-separated. Some schemes for spin filter based on the abundant interference\ncharacteristics are proposed."
    },
    {
        "anchor": "Homogenizing metamaterials, three times: The homogenization of a metamaterial made of a collection of scatterers\nperiodically disposed is studied from three different points of view.\nSpecifically tools for multiple scattering theory, functional analysis,\ndifferential geometry and optimization are used. Detailed numerical results are\ngiven and the connections between the different approaches are enlightened.",
        "positive": "High-Performance Complementary III-V Tunnel FETs with Strain Engineering: Strain engineering has recently been explored to improve tunnel field-effect\ntransistors (TFETs). Here, we report design and performance of strained\nultra-thin-body (UTB) III-V TFETs by quantum transport simulations. It is found\nthat for an InAs UTB confined in [001] orientation, uniaxial compressive strain\nin [100] or [110] orientation shrinks the band gap meanwhile reduces\n(increases) transport (transverse) effective masses. Thus it improves the ON\nstate current of both n-type and p-type UTB InAs TFETs without lowering the\nsource density of states. Applying the strain locally in the source region\nmakes further improvements by suppressing the OFF state leakage. For p-type\nTFETs, the locally strained area can be extended into the channel to form a\nquantum well, giving rise to even larger ON state current that is comparable to\nthe n-type ones. Therefore strain engineering is a promising option for\nimproving complementary circuits based on UTB III-V TFETs."
    },
    {
        "anchor": "Nonequilibrium magnons from hot electrons in antiferromagnetic systems: We describe a \\emph{nonthermal} magnon activation mechanism in\nantiferromagnetic (AFM) systems via locally equilibrated\n\\emph{spin-unpolarized} hot electrons excited by an ultrafast intense laser\npulse. We employ a quantum kinetic equation that takes into account a direct\nelectron-magnon scattering channel in either bulk AFM metal or at the interface\nof the AFM/normal-metal heterostructure. The mechanism is responsible for the\nnonequilibrium population of AFM magnon modes on a subnanosecond timescale,\nwhich are formed shortly after the local thermalization of hot electrons by\nCoulomb interactions. Nonequilibrium magnon populations can be additionally\nmanipulated by applying an external magnetic field. Our work paves the way\ntoward spin dynamics control in AFM systems via the ultrafast manipulation of\nout-of-equilibrium magnon excitations.",
        "positive": "Optical anisotropies of asymmetric double GaAs (001) Quantum Wells: In the present work, we were able to identify and characterize a new source\nof in-plane optical anisotropies (IOAs) occurring in asymmetric DQWs; namely a\nreduction of the symmetry from $D_{2d}$ to $C_{2v}$ as imposed by asymmetry\nalong the growth direction. We report on reflectance anisotropy spectroscopy\n(RAS) of double GaAs quantum wells (DQWs) structures coupled by a thin ($<2$\nnm) tunneling barrier. Two groups of DQWs systems were studied: one where both\nQWs have the same thickness (symmetric DQW) and another one where they have\ndifferent thicknesses (asymmetric DQW). RAS measures the IOAs arising from the\nintermixing of the heavy- and light- holes in the valence band when the\nsymmetry of the DQW system is lowered from $D_{2d}$ to $C_{2v}$. If the DQW is\nsymmetric, residual IOAs stem from the asymmetry of the QW interfaces; for\ninstance, associated to Ga segregation into the AlGaAs layer during the\nepitaxial growth process. In the case of an asymmetric DQW with QWs with\ndifferent thicknesses, the AlGaAs layers (that are sources of anisotropies) are\nnot distributed symmetrically at both sides of the tunneling barrier. Thus, the\nsystem losses its inversion symmetry yielding an increase of the RAS strength.\nThe RAS line shapes were compared with reflectance spectra in order to assess\nthe heavy- and light- hole mixing induced by the symmetry breakdown. The\nenergies of the optical transitions were calculated by numerically solving the\none-dimensional Schr\\\"odinger equation using a finite-differences method. Our\nresults are useful for interpretation of the transitions occurring in both,\nsymmetric and asymmetric DQWs."
    },
    {
        "anchor": "Engineering the Kitaev spin liquid in a quantum dot system: The Kitaev model on a honeycomb lattice may provide a robust topological\nquantum memory platform, but finding a material that realizes the unique spin\nliquid phase remains a considerable challenge. We demonstrate that an effective\nKitaev Hamiltonian can arise from a half-filled Fermi-Hubbard Hamiltonian where\neach site can experience a magnetic field in a different direction. As such, we\nprovide a method for realizing the Kitaev spin liquid on a single hexagonal\nplaquette made up of twelve quantum dots. Despite the small system size, there\nare clear signatures of the Kitaev spin-liquid ground state, and there is a\nrange of parameters where these signatures are predicted, allowing a potential\nplatform where Kitaev spin-liquid physics can be explored experimentally in\nquantum dot plaquettes.",
        "positive": "Evidence of electron-electron interactions around Van Hove singularities\n  of a graphene Moir\u00e9 superlattice: A variety of new and interesting correlated states have been predicted in\ngraphene monolayer doped to Van Hove singularities (VHSs) of its\ndensity-of-state (DOS). However, tuning the Fermi energy to reach a VHS of\ngraphene by either gating or chemical doping is prohibitively difficult, owning\nto their large energy distance (3 eV). Therefore, these correlated states,\nwhich arise from effects of strong electron-electron interactions at the VHSs,\nhave remained experimentally elusive. Here, we report experimental evidences of\nelectron-electron interactions around the VHSs of a twisted bilayer graphene\n(TBG) through scanning tunneling microscopy measurements. By introducing a\nsmall twisted angle between two adjacent graphene sheets, we are able to\ngenerate low-energy VHSs arbitrarily approaching the Fermi energy. The split of\nthe VHSs are observed and the symmetry breaking of electronic states around the\nVHSs are directly visualized. These results experimentally demonstrate the\nimportant effects of electron-electron interactions on electronic properties\naround the VHSs of the TBG, therefore providing motivation for further\ntheoretical and experimental studies in graphene systems with considering\nmany-body interactions."
    },
    {
        "anchor": "Negative differential thermal conductance between Weyl semimetals\n  nanoparticles through vacuum: In this work, the near-field radiative heat transfer (NFRHT) between two Weyl\nsemimetal (WSM) nanoparticles (NPs) is investigated. The numerical results show\nthat negative differential thermal conductance (NDTC) effect can be obtained in\nthis system, i.e., when the temperature of the emitter is fixed, the heat flux\ndoes not decrease monotonically with the increase of the temperature of the\nreceiver. Specifically, when the temperature of the emitter is 300 K, the heat\nflux is identical when the temperature of the receiver is 50 K or 280 K. The\nNDTC effect is attributed to the fact that the permittivity of the WSMs changes\nwith the temperature. The coupling effects of polarizability of two WSM NPs\nhave been further identified at different temperature to reveal the physical\nmechanism of the NDTC effect. In addition, the NFRHT between two Weyl WSM NPs\ncan be greatly enhanced by exciting the localized plasmon and circular modes.\nThis work indicates that the WSMs maybe promising candidate materials for\nmanipulating NFRHT.",
        "positive": "Orbital momentum excitation by interband optical transitions in a 2D\n  system illuminated by twisted light: Illumination of a two-dimensional system by a twisted light beam is\nconsidered in order to find specific effects caused by twisting. Direct\ninterband transitions between the valence and conduction bands are supposed.\nThe generation rates of the electron orbital momentum is found. A kinetic\nequation for an orbital momentum distribution function is formulated and\nsolved. The mean electron orbital momentum is found."
    },
    {
        "anchor": "Ultrahigh breakdown current density of van der Waals One Dimensional\n  $\\mathrm{PdBr_2}$: One-dimensional (1D) van der Waals (vdW) materials offer nearly defect-free\nstrands as channel material in the field-effect transistor (FET) devices and\nprobably, a better interconnect than conventional copper with higher current\ndensity and resistance to electro-migration with sustainable down-scaling. We\nreport a new halide based \"truly\" 1D few-chain atomic thread, PdBr$_2$,\nisolable from its bulk which crystallizes in a monoclinic space group C2/c.\nLiquid phase exfoliated nanowires with mean length (20$\\pm$1)$\\mu$m transferred\nonto SiO$_2$/Si wafer with a maximum aspect ratio of 5000 confirms the lower\ncleavage energy perpendicular to chain direction. Moreover, an isolated\nnanowire can also sustain current density of 200 MA/cm$^\\mathrm{2}$ which is\natleast one-order higher than typical copper interconnects. However, local\ntransport measurement via conducting atomic force microscopy (CAFM) tip along\nthe cross direction of the single chain records a much lower current density\ndue to the anisotropic electronic band structure. While 1D nature of the\nnanoobject can be linked with non-trivial collective quantum behavior, vdW\nnature could be beneficial for the new pathways in interconnect fabrication\nstrategy with better control of placement in an integrated circuit (IC).",
        "positive": "Coherent population trapping combined with cycling transitions for\n  quantum dot hole spins using triplet trion states: Optical spin rotations and cycling transitions for measurement are normally\nincompatible in quantum dots, presenting a fundamental problem for quantum\ninformation applications. Here we show that for a hole spin this problem can be\naddressed using a trion with one hole in an excited orbital, where strong\nspin-orbit interaction tilts the spin. Then, a particular trion triplet forms a\ndouble $\\Lambda$ system, even in a Faraday magnetic field, which we use to\ndemonstrate fast hole spin initialization and coherent population trapping. The\nlowest trion transitions still strongly preserve spin, thus combining fast\noptical spin control with cycling transitions for spin readout."
    },
    {
        "anchor": "Magnetic Quantum Tunneling: Insights from Simple Molecule-Based Magnets: This article takes a broad view of the understanding of magnetic bistability\nand magnetic quantum tunneling in single-molecule magnets (SMMs), focusing on\nthree families of relatively simple, low-nuclearity transition metal clusters:\nspin S = 4 Ni4, Mn(III)3 (S = 2 and 6) and Mn(III)6 (S = 4 and 12). The Mn(III)\ncomplexes are related by the fact that they contain triangular Mn3 units in\nwhich the exchange may be switched from antiferromagnetic to ferromagnetic\nwithout significantly altering the coordination around the Mn(III) centers,\nthereby leaving the single-ion physics more-or-less unaltered. This allows for\na detailed and systematic study of the way in which the individual-ion\nanisotropies project onto the molecular spin ground state in otherwise\nidentical low- and high-spin molecules, thus providing unique insights into the\nkey factors that control the quantum dynamics of SMMs, namely: (i) the height\nof the kinetic barrier to magnetization relaxation; and (ii) the transverse\ninteractions that cause tunneling through this barrier. Numerical calculations\nare supported by an unprecedented experimental data set (17 different\ncompounds), including very detailed spectroscopic information obtained from\nhigh-frequency electron paramagnetic resonance and low-temperature hysteresis\nmeasurements. Diagonalization of the multi-spin Hamiltonian matrix is necessary\nin order to fully capture the interplay between exchange and local anisotropy,\nand the resultant spin-state mixing which ultimately gives rise to the\ntunneling matrix elements in the high symmetry SMMs (ferromagnetic Mn3 and\nNi4). The simplicity (low-nuclearity, high-symmetry, weak disorder, etc..) of\nthe molecules highlighted in this study proves to be of crucial importance.",
        "positive": "Rate of energy absorption by a closed ballistic ring: We make a distinction between the spectroscopic and the mesoscopic\nconductance of closed systems. We show that the latter is not simply related to\nthe Landauer conductance of the corresponding open system. A new ingredient in\nthe theory is related to the non-universal structure of the perturbation matrix\nwhich is generic for quantum chaotic systems. These structures may created\nbottlenecks that suppress the diffusion in energy space, and hence the rate of\nenergy absorption. The resulting effect is not merely quantitative: For a\nring-dot system we find that a smaller Landauer conductance implies a smaller\nspectroscopic conductance, while the mesoscopic conductance increases. Our\nconsiderations open the way towards a realistic theory of dissipation in closed\nmesoscopic ballistic devices."
    },
    {
        "anchor": "Mechanically stacked 1 nm thick carbon nanosheets: Ultrathin layered\n  materials with tunable optical, chemical and electrical properties: Carbon nanosheets are mechanically stable free-standing two-dimensional\nmaterials with a thickness of ~1 nm and well defined physical and chemical\nproperties. They are made by radiation induced cross-linking of aromatic\nself-assembled monolayers. Here we present a route to the scalable fabrication\nof multilayer nanosheets with tunable electrical, optical and chemical\nproperties on insulating substrates. Stacks up to five nanosheets with sizes of\n~1 cm^2 on oxidized silicon were studied. Their optical characteristics were\ninvestigated by visual inspection, optical microscopy, UV/Vis reflection\nspectroscopy and model calculations. Their chemical composition was studied by\nX-ray photoelectron spectroscopy. The multilayer samples were then annealed in\nultra high vacuum at various temperatures up to 1100 K. A subsequent\ninvestigation by Raman, X-ray photoelectron and UV/Vis reflection spectroscopy\nas well as by electrical four-point probe measurements demonstrates that the\nlayered nanosheets transform into nanocrystalline graphene. This structural and\nchemical transformation is accompanied by changes in the optical properties and\nelectrical conductivity and opens up a new path for the fabrication of\nultrathin functional conductive coatings.",
        "positive": "Charge equilibration in integer and fractional quantum Hall edge\n  channels in a generalized Hall-bar device: Charge equilibration between quantum-Hall edge states can be studied to\nreveal geometric structure of edge channels not only in the integer quantum\nHall (IQH) regime but also in the fractional quantum Hall (FQH) regime\nparticularly for hole-conjugate states. Here we report on a systematic study of\ncharge equilibration in both IQH and FQH regimes by using a generalized Hall\nbar, in which a quantum Hall state is nested in another quantum Hall state with\ndifferent Landau filling factors. This provides a feasible way to evaluate\nequilibration in various conditions even in the presence of scattering in the\nbulk region. The validity of the analysis is tested in the IQH regime by\nconfirming consistency with previous works. In the FQH regime, we find that the\nequilibration length for counter-propagating $\\delta \\nu $ = 1 and $\\delta \\nu\n$ = -1/3 channels along a hole-conjugate state at Landau filling factor $\\nu $\n= 2/3 is much shorter than that for co-propagating $\\delta \\nu $ = 1 and\n$\\delta \\nu $ = 1/3 channels along a particle state at $\\nu $ = 4/3. The\ndifference can be associated to the distinct geometric structures of the edge\nchannels. Our analysis with generalized Hall bar devices would be useful in\nstudying edge equilibration and edge structures."
    },
    {
        "anchor": "Edge states in a non-Hermitian topological crystalline insulator: Breaking Hermiticity in topological systems gives rise to intriguing\nphenomena, such as the exceptional topology and the non-Hermitian skin effect.\nIn this work, we study a non-Hermitian topological crystalline insulator\nsitting on the Kekul\\'{e}-modulated honeycomb lattice with balanced gain and\nloss. We find that the gaplessness of the topological edge states in the\nnon-Hermitian system is insensitive to edge geometries under moderate strength\nof gain and loss, unlike the cases of Hermitian topological crystalline\ninsulators that depend on edge geometries crucially. We focus on two types of\ngain and loss configurations, which are $PT$-symmetric and $PT$-asymmetric,\nrespectively. For the $PT$-symmetric configuration, the Dirac point of the\ntopological edge states in the Hermitian molecular-zigzag-terminated ribbons\nsplits into a pair of exceptional points. The edge gap in the Hermitian\narmchair-terminated ribbons vanishes and a Dirac point forms as far as moderate\ngain and loss is induced. The band gaps of edge and bulk states in the\nHermitian armchair-terminated ribbons close simultaneously for the\n$PT$-asymmetric configuration.",
        "positive": "Ballistic Hot Electron Transport in Graphene: We theoretically study the inelastic scattering rate and the carrier mean\nfree path for energetic hot electrons in graphene, including both\nelectron-electron and electron-phonon interactions. Taking account of optical\nphonon emission and electron-electron scattering, we find that the inelastic\nscattering time $\\tau \\sim 10^{-2}-10^{-1} \\mathrm{ps}$ and the mean free path\n$l \\sim 10-10^2 \\mathrm{nm}$ for electron densities $n = 10^{12}-10^{13}\n\\mathrm{cm}^{-2}$. In particular, we find that the mean free path exhibits a\nfinite jump at the phonon energy $200 \\mathrm{meV}$ due to electron-phonon\ninteraction. Our results are directly applicable to device structures where\nballistic transport is relevant with inelastic scattering dominating over\nelastic scattering."
    },
    {
        "anchor": "Orientation dependent current-induced motion of skyrmions with various\n  topologies: We study the current-driven motion of metastable localized spin structures\nwith various topological charges in a (Pt$_{1-x}$Ir$_{x}$)/Fe bilayer on a\nPd(111) surface by combining atomistic spin model simulations with an approach\nbased on the generalized Thiele equation. We demonstrate that besides a\ndistinct dependence on the topological charge itself the dynamic response of\nskyrmionic structures with topological charges $\\mathrm{Q} = -1$ and\n$\\mathrm{Q}= 3$ to a spin-polarized current exhibits an orientation dependence.\nWe further show that such an orientation dependence can be induced by applying\nan in-plane external field, possibly opening up a new pathway to the\nmanipulation of skyrmion dynamics.",
        "positive": "Growth mechanism of cluster-assembled surfaces: from sub-monolayer to\n  thin film regime: Nanostructured films obtained by the assembling of preformed atomic clusters\nare of strategic importance for a wide variety of applications. The deposition\nof clusters produced in the gas phase onto a substrate offers the possibility\nto control and engineer the structural and functional properties of the\ncluster-assembled films. To date the microscopic mechanisms underlying the\ngrowth and structuring of cluster-assembled films are poorly understood, and in\nparticular the transition from the sub-monolayer to the thin film regime is\nexperimentally unexplored. Here we report the systematic characterization by\nAtomic Force Microscopy of the evolution of the structural properties of\ncluster-assembled films deposited by Supersonic Cluster Beam Deposition. As a\nparadigm of nanostructured systems, we have focused our attention on\ncluster-assembled zirconia films, investigating the influence of the building\nblocks dimensions on the growth mechanisms and on the roughening of the thin\nfilms, following the growth process from the early stages of the sub-monolayer\nto the thin film regime. Our results demonstrate that the growth dynamics in\nthe sub-monolayer regime determines different morphological properties of the\ncluster-assembled thin film. The evolution of roughness with the number of\ndeposited clusters reproduces exactly the growth exponent of the ballistic\ndeposition in the 2+1 model, from the sub-monolayer to the thin film regime."
    },
    {
        "anchor": "Inverse exciton spin orientation due to trion formation in modulation\n  doped quantum wells: Time-resolved and time-integrated circularly polarized photoluminescence of\nexcitons and trions in external magnetic fields up to 10 T has been studied in\nundoped and n-type doped quantum well structures based on ZnSe. In an undoped\nstructure, a circular polarization of photoluminescence induced by magnetic\nfields corresponded to the Boltzmann distribution of excitons on Zeeman\nsublevels. The inverse spin orientation of excitons is observed in doped\nsamples with a carrier density of $3 \\times 10^{10}$ cm$^{-2}$ and higher.\nModel calculations show that the reason for the inverse spin orientation is the\neffective depletion of the lowest-exciton Zeeman sublevel as a result of the\nspin-dependent formation of trions. The trion formation time as a result of\nexciton-electron binding was determined as 2 ps. This is noticeably shorter\nthan the characteristic time of the exciton-photon interaction. The observed\neffect can be considered as a way of spin manipulation by electric fields.",
        "positive": "Macroscopic, layered onion shell like magnetic domain structure\n  generated in YIG film using ultrashort, megagauss magnetic pulses: Study of the formation and evolution of large scale, ordered structures is an\nenduring theme in science. The generation, evolution and control of large sized\nmagnetic domains are intriguing and challenging tasks, given the complex nature\nof competing interactions present in any magnetic system. Here, we demonstrate\nlarge scale non-coplanar ordering of spins, driven by picosecond, megagauss\nmagnetic pulses derived from a high intensity, femtosecond laser. Our studies\non a specially designed Yttrium Iron Garnet (YIG)/dielectric/metal film\nsandwich target, show the creation of complex, large, concentric, elliptical\nshaped magnetic domains which resemble the layered shell structure of an onion.\nThe largest shell has a major axis of over hundreds of micrometers, in stark\ncontrast to conventional sub micrometer scale polygonal, striped or bubble\nshaped magnetic domains found in magnetic materials, or the large dumbbell\nshaped domains produced in magnetic films irradiated with accelerator based\nrelativistic electron beams. Through micromagnetic simulations, we show that\nthe giant magnetic field pulses create ultrafast terahertz (THz) spin waves. A\nsnapshot of these fast propagating spin waves is stored as the layered onion\nshell shaped domains in the YIG film. Typically, information transport via spin\nwaves in magnonic devices occurs in the gigahertz (GHz) regime, where the\ndevices are susceptible to thermal disturbances at room temperature. Our\nintense laser light pulse - YIG sandwich target combination, paves the way for\nroom temperature table-top THz spin wave devices, which operate just above or\nin the range of the thermal noise floor. This dissipation-less device offers\nultrafast control of spin information over distances of few hundreds of\nmicrons."
    },
    {
        "anchor": "Signatures of Majorana fermions in hybrid normal-superconducting rings: We investigate persistent currents in metallic rings interrupted by a Coulomb\nblockaded topological superconducting segment. We show that the presence of\nMajorana bound states in the superconductor is reflected in the emergence of an\nh/e harmonics in the persistent current, whose sign is determined by the\nfermion parity of the superconductor. The Majorana bound states further render\nthe current finite at zero flux, nevertheless the resulting peculiar symmetry\nof the persistent current is compatible with a free energy that is even in\ntime-reversal symmetry breaking fields. These unique features of the persistent\ncurrents are robust against disorder and provide unambiguous signatures of the\npresence of Majorana fermions.",
        "positive": "Sub-Sharvin conductance and enhanced shot noise in doped graphene: Ideal Sharvin contact in a multimode regime shows the conductance\n$G\\approx{}G_{\\rm Sharvin}=g_0k_F{}W/\\pi$ (with $g_0$ the conductance quantum,\n$k_F$ the Fermi momentum, and $W$ the contact width) accompanied by strongly\nsuppressed shot-noise quantified by small Fano factor $F\\approx{}0$. For\nballistic graphene away from the charge-neutrality point the sub-Sharvin\ntransport occurs, characterised by suppressed conductance\n$G\\approx{}(\\pi/4)\\,G_{\\rm Sharvin}$ and enhanced shot noise $F\\approx{}1/8$.\nAll these results can be derived from a basic model of quantum scattering,\ninvolving assumptions of infinite height and perfectly rectangular shape of the\npotential barrier in the sample. Here we have carried out the numerical\nanalysis of the scattering on a family of smooth barriers of finite height\ninterpolating between parabollic and rectangular shapes. We find that tuning\nthe barrier shape one can modify the asymmetry between electron- and hole-doped\nsystems. For electronic dopings, the system crosses from Sharvin to sub-Sharvin\ntransport regime (indicated by both the conductance and the Fano factor) as the\npotential becomes closer to the rectangular shape. In contrast, for hole\ndopings, the conductivity is strongly suppressed when the barrier is parabolic\nand slowly converges to $G\\approx{}(\\pi/4)\\,G_{\\rm Sharvin}$ as the potential\nevolves towards rectangular shape. In such a case the Sharvin transport regime\nis inaccessible, shot noise is generically enhanced (with much slower\nconvergence to $F\\approx{}1/8$) comparing to the electron-doped case, and\naperiodic oscillations of both $G$ and $F$ are prominent due to the formation\nof quasibound states."
    },
    {
        "anchor": "Resonant scattering of two-dimensional honeycomb PT dipole structure: We studied numerically electromagnetic response of the finite periodic\nstructure consisting of the ${\\cal{PT}}$ dipoles represented by two infinitely\nlong, parallel cylinders with the opposite sign of the imaginary part of a\nrefractive index which are centered at the positions of two-dimensional\nhoneycomb lattice. We observed that the total scattered energy reveals series\nof sharp resonances at which the energy increases by two orders of magnitude\nand an incident wave is scattered only in a few directions given by spatial\nsymmetry of periodic structure. We explain this behavior by analysis of the\ncomplex frequency spectra associated with an infinite honeycomb array of the\n${\\cal{PT}}$ dipoles and identify the lowest resonance with the broken\n${\\cal{PT}}$-symmetry mode formed by a doubly degenerate pair with complex\nconjugate eigenfrequencies corresponding to the $K$-point of the reciprocal\nlattice.",
        "positive": "Bloch gain in dc-ac-driven semiconductor superlattices in the absence of\n  electric domains: We study theoretically the feasibility of amplification and generation of\nterahertz radiation in dc-ac-driven semiconductor superlattices in the absence\nof electric domains. We find that if in addition to dc bias a strong THz pump\nfield is applied, Bloch gain profile for a small THz signal can be achieved\nunder conditions of positive static differential conductivity. Here the\npositive differential conductivity arises, similarly to the case of\nlarge-signal amplification scheme [H. Kroemer, cond-mat/0009311)], due to\nmodifications of dc current density caused by the application of high-frequency\nac field [K. Unterrainer \\textit{et al.}, Phys. Rev. Lett. \\textbf{76}, 2973\n(1996)]. Whereas the sign of absorption at low and zero frequencies is\nsensitive to the ac fields, the gain profile in the vicinity of gain maximum is\nrobust. We suggest to use this ac-induced effect in a starter for THz Bloch\noscillator. Our analysis demonstrates that the application of a short THz pulse\nto a superlattice allows to suppress the undesirable formation of electric\ndomains and reach a sustained large-amplitude operation of the dc-biased Bloch\nscillator."
    },
    {
        "anchor": "Nanoelectromechanics of shuttle devices: A single-electron tunneling (SET) device with a nanoscale central island that\ncan move with respect to the bulk source- and drain electrodes allows for a\nnanoelectromechanical (NEM) coupling between the electrical current through the\ndevice and mechanical vibrations of the island. Although an electromechanical\n\"shuttle\" instability and the associated phenomenon of single-electron\nshuttling were predicted more than 15 years ago, both theoretical and\nexperimental studies of NEM-SET structures are still carried out. New\nfunctionalities based on quantum coherence, Coulomb correlations and coherent\nelectron-spin dynamics are of particular current interest. In this article we\npresent a short review of recent activities in this area.",
        "positive": "Spin Density Waves and Domain Wall Interactions in Nanowires: We investigated how the dynamics of a domain wall are affected by the\npresence of spin density waves in a ferromagnetic wire. Domain walls and other\nscattering centres can cause coherent spin density waves to propagate through a\nwire when a current is applied. In some cases the spin torque due to these\nscattered electrons can be enhanced such that it is on a par with the exchange\nand anisotropy energies controlling the shape and dynamics of the domain wall.\nIn such a case we find that the spin density waves enhance the current induced\ndomain wall motion, allowing for domain wall motion with smaller current\npulses. Here we consider a system involving two domain walls and focus on how\nthe motion of the second domain wall is modified by the spin density waves\ncaused by the presence of the first domain wall."
    },
    {
        "anchor": "An exciton interacting with a moire lattice -- polarons, strings, and\n  optical probing of spin correlations: We develop a general theory for how an exciton in an atomically thin\ntransition metal dichacogenide (TMD) monolayer couples to spin and charge\ncorrelations in an adjacent moire lattice created by a TMD bi-layer. Virtual\ntunneling of charge carriers, assumed for concreteness to be holes, between the\nmoire lattice and the monolayer combined with the presence of bound\nhole-exciton states, i.e. trions, give rise to an effective interaction between\nthe moire holes and the exciton. In addition to the Umklapp scattering, we show\nthat this interaction is spin-dependent and therefore couples the exciton to\nthe spin correlations of the moire holes, which may be in- as well as\nout-of-plane. We then use our theory to examine two specific examples where the\nmoire holes form in-plane ferromagnetic or anti-ferromagnetic order. In both\ncases, the exciton creates spin waves in the moire lattice, which we analyse by\nusing a self-consistent Born approximation that includes such processes to\ninfinite order. We show that the competition between magnetic order and exciton\nmotion leads to the formation of a well-defined quasiparticle consisting of the\nexciton surrounded by a cloud of magnetic frustration in the moire lattice\nsites below. For the anti-ferromagnet, we furthermore demonstrate the presence\nof the elusive geometric string excitations and discuss how they can be\nobserved via their smoking gun energy dependence on the spin-spin coupling,\nwhich can be tuned by varying the twist angle of the moire bi-layer. All these\nphenomena have clear signatures in the exciton spectrum, and as such our\nresults illustrate that excitons are promising probes providing optical access\nto the spin correlations of new quantum phases predicted to exist in TMD\nmaterials.",
        "positive": "High Photocurrent in Gated Graphene-Silicon Hybrid Photodiodes: Graphene/silicon (G/Si) heterojunction based devices have been demonstrated\nas high responsivity photodetectors that are potentially compatible with\nsemiconductor technology. Such G/Si Schottky junction diodes are typically in\nparallel with gated G/silicon dioxide (SiO$_2$)/Si areas, where the graphene is\ncontacted. Here, we utilize scanning photocurrent measurements to investigate\nthe spatial distribution and explain the physical origin of photocurrent\ngeneration in these devices. We observe distinctly higher photocurrents\nunderneath the isolating region of graphene on SiO$_2$ adjacent to the Schottky\njunction of G/Si. A certain threshold voltage (V$_T$) is required before this\ncan be observed, and its origins are similar to that of the threshold voltage\nin metal oxide semiconductor field effect transistors. A physical model serves\nto explain the large photocurrents underneath SiO$_2$ by the formation of an\ninversion layer in Si. Our findings contribute to a basic understanding of\ngraphene / semiconductor hybrid devices which, in turn, can help in designing\nefficient optoelectronic devices and systems based on such 2D/3D\nheterojunctions."
    },
    {
        "anchor": "Optically induced nuclear spin polarization in a single GaAs/AlGaAs\n  quantum well probed by a resistance detection method in the fractional\n  quantum Hall regime: We study the optically pumped nuclear spin polarization in a single\nGaAs/AlGaAs quantum well in the quantum Hall system. We apply resistive\ndetection via the contact hyperfine interaction, which provides high\nsensitivity and selectivity, to probe a small amount of polarized nuclear spins\nin a single well. The properties of the optical nuclear spin polarization are\nclearly observed. We theoretically discuss the nuclear spin dynamics\naccompanied with doped electrons to analyze the experimental data. The optical\nnuclear polarization spectra exhibit electron-spin-resolved lowest Landau level\ninterband transitions. We find that the phonon emission process, which normally\nassists the optical pumping process, influences the optical nuclear spin\npolarization. We also discuss that the electron-electron interaction can play\nan important role in the optical nuclear spin polarization.",
        "positive": "Footprints of hyperfine, spin-orbit, and decoherence effects in Pauli\n  spin blockade: We detect in real time inter-dot tunneling events in a weakly coupled two\nelectron double quantum dot in GaAs. At finite magnetic fields, we observe two\ncharacteristic tunneling times, T_d and T_b, belonging to, respectively, a\ndirect and a blocked (spin-flip-assisted) tunneling. The latter corresponds to\nlifting of a Pauli spin blockade and the tunneling times ratio eta=T_b/T_d\ncharacterizes the blockade efficiency. We find pronounced changes in the\nbehavior of eta upon increasing the magnetic field, with eta increasing,\nsaturating and increasing again. We explain this behavior as due to the\ncrossover of the dominant blockade lifting mechanism from the hyperfine to\nspin-orbit interactions and due to a change in the contribution of the charge\ndecoherence."
    },
    {
        "anchor": "Statistical theory of materials with nanoscale phase separation: Materials with nanoscale phase separation are considered. These materials are\nformed by a mixture of several phases, so that inside one phase there exist\nnanosize inclusions of other phases, with random shapes and random spatial\nlocations. A general approach is described for treating statistical properties\nof such materials with nanoscale phase separation. Averaging over the random\nphase configurations, it is possible to reduce the problem to the set of\nhomogeneous phase replicas, with additional equations defining the geometric\nweights of different phases in the mixture. The averaging over phase\nconfigurations is mathematically realized as the functional integration over\nthe manifold indicator functions. This procedure leads to the definition of an\neffective renormalized Hamiltonian taking into account the existence of\ncompeting phases. Heterophase systems with mesoscopic phase separation can\noccur for different substances. The approach is illustrated by the model of a\nhigh-temperature superconductor with non-superconducting admixture and by the\nmodel of a ferroelectric with paraelectric random inclusions.",
        "positive": "Critical issues in the formation of quantum computer test structures by\n  ion implantation: The formation of quantum computer test structures in silicon by ion\nimplantation enables the characterization of spin readout mechanisms with\nensembles of dopant atoms and the development of single atom devices. We\nbriefly review recent results in the characterization of spin dependent\ntransport and single ion doping and then discuss the diffusion and segregation\nbehaviour of phosphorus, antimony and bismuth ions from low fluence, low energy\nimplantations as characterized through depth profiling by secondary ion mass\nspectrometry (SIMS). Both phosphorus and bismuth are found to segregate to the\nSiO2/Si interface during activation anneals, while antimony diffusion is found\nto be minimal. An effect of the ion charge state on the range of antimony ions,\n121Sb25+, in SiO2/Si is also discussed."
    },
    {
        "anchor": "Effects of the two-dimensional Coulomb interaction in both Fermi\n  velocity and energy gap for Dirac-like electrons at finite temperature: We describe both the Fermi velocity and the mass renormalization due to the\ntwo-dimensional Coulomb interaction in the presence of a thermal bath. To\nachieve this, we consider an anisotropic version of pseudo quantum\nelectrodynamics (PQED), within a perturbative approach in the fine-structure\nconstant $\\alpha$. Thereafter, we use the so-called imaginary-time formalism\nfor including the thermal bath. In the limit $T\\rightarrow 0$, we calculate the\nrenormalized mass $m^R(p)$ and compare this result with the experimental\nfindings for the energy band gap in monolayers of transition metal\ndichalcogenides, namely, WSe$_2$ and MoS$_2$. In these materials, the\nquasi-particle excitations behave as a massive Dirac-like particles in the\nlow-energy limit, hence, its mass is related to the energy band gap of the\nmaterial. In the low-temperature limit $T\\ll v_F p $, where $v_F p$ is taken as\nthe Fermi energy, we show that $m^R(p)$ decreases linearly on the temperature,\ni.e, $m^R(p,T)-m^R(p,T\\rightarrow 0)\\approx -A_\\alpha T +O(T^3)$, where\n$A_\\alpha$ is a positive constant. On the other hand, for the renormalized\nFermi velocity, we find that $v^R_F(p,T)-v^R_F(p,T\\rightarrow 0)\\approx\n-B_\\alpha T^3 +O(T^5)$, where $B_\\alpha$ is a positive constant. We also\nperform numerical tests which confirm our analytical results.",
        "positive": "Quantum Hall-like effect for cold atoms in non-Abelian gauge potentials: We study the transport of cold fermionic atoms trapped in optical lattices in\nthe presence of artificial Abelian or non-Abelian gauge potentials. Such\nexternal potentials can be created in optical lattices in which atom tunneling\nis laser assisted and described by commutative or non-commutative tunneling\noperators. We show that the Hall-like transverse conductivity of such systems\nis quantized by relating the transverse conductivity to topological invariants\nknown as Chern numbers. We show that this quantization is robust in non-Abelian\npotentials. The different integer values of this conductivity are explicitly\ncomputed for a specific non-Abelian system which leads to a fractal phase\ndiagram."
    },
    {
        "anchor": "Rotational States of Magnetic Molecules: We study a magnetic molecule that exhibits spin tunneling and is free to\nrotate about its anisotropy axis. Exact low-energy eigenstates of the molecule\nthat are superpositions of spin and rotational states are obtained. We show\nthat parameter $\\alpha = 2(\\hbar S)^2/(I\\Delta)$ determines the ground state of\nthe molecule. Here $\\hbar S$ is the spin, $I$ is the moment of inertia, and\n$\\Delta$ is the tunnel splitting. The magnetic moment of the molecule is zero\nat $\\alpha < \\alpha_c = [1-1/(2S)^{2}]^{-1}$ and non-zero at $\\alpha >\n\\alpha_c$. At $\\alpha \\to \\infty$ the spin of the molecule localizes in one of\nthe directions along the anisotropy axis.",
        "positive": "A Brief Review on Syntheses, Structures and Applications of Nanoscrolls: Nanoscrolls are papyrus-like nanostructures which present unique properties\ndue to their open ended morphology. These properties can be exploited in a\nplethora of technological applications, leading to the design of novel and\ninteresting devices. During the past decade, significant advances in the\nsynthesis and characterization of these structures have been made, but many\nchallenges still remain. In this mini review we provide an overview on their\nhistory, experimental synthesis methods, basic properties and application\nperspectives."
    },
    {
        "anchor": "Normal and inverted hysteresis in perovskite solar cells: Hysteretic effects are investigated in perovskite solar cells in the standard\nFTO/TiO$_2$/CH$_3$NH$_3$PbI$_{3-x}$Cl$_x$/spiro-OMeTAD/Au configuration. We\nreport normal (NH) and inverted hysteresis (IH) in the J-V characteristics\noccurring for the same device structure, the behavior strictly depending on the\npre-poling bias. NH typically appears at pre-poling biases larger than the open\ncircuit bias, while pronounced IH occurs for negative bias pre-poling. The\ntransition from NH to IH is marked by a intermediate mixed hysteresis behavior\ncharacterized by a crossing point in the J-V characteristics. The measured J-V\ncharacteristics are explained quantitatively by the dynamic electrical model\n(DEM). Furthermore, the influence of the bias scan rate on the NH/IH hysteresis\nis discussed based on the time evolution of the non-linear polarization.\nIntroducing a three step measurement protocol, which includes stabilization,\npre-poling and measurement, we put forward the difficulties and possible\nsolutions for a correct PCE evaluation.",
        "positive": "Simulation of nanostructure-based high-efficiency solar cells:\n  challenges, existing approaches and future directions: Many advanced concepts for high-efficiency photovoltaic devices exploit the\npeculiar optoelectronic properties of semiconductor nanostructures such as\nquantum wells, wires and dots. While the optics of such devices is only\nmodestly affected due to the small size of the structures, the optical\ntransitions and electronic transport can strongly deviate from the simple bulk\npicture known from conventional solar cell devices. This review article\ndiscusses the challenges for an adequate theoretical description of the\nphotovoltaic device operation arising from the introduction of nanostructure\nabsorber and/or conductor components and gives an overview of existing device\nsimulation approaches."
    },
    {
        "anchor": "Andreev interference in the surface accumulation layer of half-shell\n  InAsSb/Al hybrid nanowires: Understanding the spatial distribution of charge carriers in III-V nanowires\nproximity coupled to superconductors is important for the design and\ninterpretation of experiments based on hybrid quantum devices. In this letter,\nthe gate-dependent surface accumulation layer of InAsSb/Al nanowires was\nstudied by means of Andreev interference in a parallel magnetic field. Both\nuniform hybrid nanowires and devices featuring a short Josephson junction\nfabricated by shadow lithography, exhibited periodic modulation of the\nswitching current. The period corresponds to a flux quantum through the\nnanowire diameter and is consistent with Andreev bound states occupying a\ncylindrical surface accumulation layer. The spatial distribution was tunable by\na gate potential as expected from electrostatic models.",
        "positive": "Extended Bose-Hubbard model with incompressible states at fractional\n  numbers: The Bose-Hubbard model is extended to include nearest and far neighbor\ninteractions and is related to the fractional quantum Hall effect (FQHE). Both\nmodels may be studied in optical lattices with quantum gases. The ground state\nis calculated for the extended Bose-Hubbard model with strong repulsive\ninteractions (weak hopping). Incompressible Mott insulator states are found at\nrational filling fractions compatible with the principal and secondary FQHE\nfilling fractions of the lowest Landau levels observed experimentally. It is\ndiscussed to which extent these states at fractional filling survive or\nundergoes a Mott insulator transition to a superfluid as hopping terms are\nincluded."
    },
    {
        "anchor": "Ultraslow Electron Spin Dynamics in GaAs Quantum Wells Probed by\n  Optically Pumped NMR: Optically pumped nuclear magnetic resonance (OPNMR) measurements were\nperformed in two different electron-doped multiple quantum well samples near\nthe fractional quantum Hall effect ground state nu=1/3. Below 0.5K, the spectra\nprovide evidence that spin-reversed charged excitations of the nu=1/3 ground\nstate are localized over the NMR time scale of ~40 microseconds. Furthermore,\nby varying NMR pulse parameters, the electron spin temperature (as measured by\nthe Knight shift) could be driven above the lattice temperature, which shows\nthat the value of the electron spin-lattice relaxation time lies between 100\nmicroseconds and 500 milliseconds at nu=1/3.",
        "positive": "Amplification of Acoustic Waves in Graphene Nanoribbon in the Presence\n  of External Electric and Magnetic Field: Amplification of Acoustic Waves in Armchair Graphene Nanoribbon (AGNR) in the\npresence of an external Electric and Magnetic field was studied using the\nBoltzmann's kinetic equation. The general expression for the Amplification\n$(\\Gamma_{\\perp}/\\Gamma_0)$ was obtained in the region $ql >> 1$ for the energy\ndispersion $\\varepsilon(\\vec{p})$ near the Fermi point. For various parameters\nof the quantized wave vector ($\\beta$), the analysis of\n$\\Gamma_{\\perp}/\\Gamma_0$ against the sub-bands index $(p_i)$; width of AGNR;\nand magnetic strength $(\\Omega\\tau)$, were numerically analyzed. The results\nshowed a linear relation for $\\Gamma_{\\perp}/\\Gamma_0$ with constant electric\nfield $(\\vec{E})$ but non-linear for $\\Gamma_{\\perp}/\\Gamma_0$ with $q$ or\n$\\Omega\\tau$. Sound Amplification in AGNR is reported with an increase in\nAcoustic wave number $(\\vec{q}) > 1.5\\times 10^{7}cm^{-1}$. This can cause\nSASER in Armchair Graphene Nanoribbon (AGNR)."
    },
    {
        "anchor": "Ligand-based transport resonances of single-molecule magnet spin\n  filters: Suppression of the Coulomb blockade and determination of the\n  orientation of the magnetic easy axis: We investigate single molecule magnet transistors (SMMTs) with ligands that\nsupport transport resonances. We find the lowest unoccupied molecular orbitals\nof Mn12-benzoate SMMs (with and without thiol or methyl-sulfide termination) to\nbe on ligands, the highest occupied molecular orbitals being on the Mn12\nmagnetic core. We predict gate controlled switching between Coulomb blockade\nand coherent resonant tunneling in SMMTs based on such SMMs, strong spin\nfiltering by the SMM in both transport regimes, and that if such switching is\nobserved then the magnetic easy axis of the SMM is parallel to the direction of\nthe current through the SMM.",
        "positive": "Landau levels in deformed bilayer graphene at low magnetic fields: We review the effect of uniaxial strain on the low-energy electronic\ndispersion and Landau level structure of bilayer graphene. Based on the\ntight-binding approach, we derive a strain-induced term in the low-energy\nHamiltonian and show how strain affects the low-energy electronic band\nstructure. Depending on the magnitude and direction of applied strain, we\nidentify three regimes of qualitatively different electronic dispersions. We\nalso show that in a weak magnetic field, sufficient strain results in the\nfilling factor ff=+-4 being the most stable in the quantum Hall effect\nmeasurement, instead of ff=+-8 in unperturbed bilayer at a weak magnetic field.\nTo mention, in one of the strain regimes, the activation gap at ff=+-4 is, down\nto very low fields, weakly dependent on the strength of the magnetic field."
    },
    {
        "anchor": "Fabrication of all diamond scanning probes for nanoscale magnetometry: The electronic spin of the nitrogen vacancy (NV) center in diamond forms an\natomically sized, highly sensitive sensor for magnetic fields. To harness the\nfull potential of individual NV centers for sensing with high sensitivity and\nnanoscale spatial resolution, NV centers have to be incorporated into scanning\nprobe structures enabling controlled scanning in close proximity to the sample\nsurface. Here, we present an optimized procedure to fabricate single-crystal,\nall-diamond scanning probes starting from commercially available diamond and\nshow a highly efficient and robust approach for integrating these devices in a\ngeneric atomic force microscope. Our scanning probes consisting of a scanning\nnanopillar (200 nm diameter, $1-2\\,\\mu$m length) on a thin ($< 1\\mu$m)\ncantilever structure, enable efficient light extraction from diamond in\ncombination with a high magnetic field sensitivity\n($\\mathrm{\\eta_{AC}}\\approx50\\pm20\\,\\mathrm{nT}/\\sqrt{\\mathrm{Hz}}$). As a\nfirst application of our scanning probes, we image the magnetic stray field of\na single Ni nanorod. We show that this stray field can be approximated by a\nsingle dipole and estimate the NV-to-sample distance to a few tens of\nnanometer, which sets the achievable resolution of our scanning probes.",
        "positive": "On Binding Energy of Trions in Bulk Materials: We study the negatively $T^{-}$ and positively $T^{+}$ charged trions in bulk\nmaterials in the effective mass approximation within the framework of a\npotential model. The binding energies of trions in various semiconductors are\ncalculated by employing Faddeev equation in configuration space. Results of\ncalculations of the binding energies for $T^{-}$ are consistent with previous\ncomputational studies and are in reasonable agreement with experimental\nmeasurements, while the $T^{+}$ is unbound for all considered cases. The\nmechanism of formation of the binding energy of trions is analysed by comparing\ncontributions of a mass-polarization term related to kinetic energy operators\nand a term related to the Coulomb repulsion of identical particles."
    },
    {
        "anchor": "Efficient Exciton Transport in Strongly Quantum-Confined Silicon Quantum\n  Dots: First-order perturbation theory and many-body Green function analysis are\nused to quantify the influence of size, surface reconstruction and surface\ntreatment on exciton transport between small silicon quantum dots. Competing\nradiative processes are also considered in order to determine how exciton\ntransport efficiency is influenced. The analysis shows that quantum confinement\ncauses small (~1 nm) Si quantum dots to exhibit exciton transport efficiencies\nfar exceeding that of their larger counterparts. We also find that surface\nreconstruction significantly influences the absorption cross section and leads\nto a large reduction in both transport rate and efficiency. Exciton transport\nefficiency is higher for hydrogen passivated dots as compared with those\nterminated with more electronegative ligands. This is because such ligands\ndelocalize electron wave functions towards the surface and result in a lower\ndipole moment. Such behavior is not predicted by F\\\"orster theory, built on a\ndipole-dipole approximation, because higher order multi-poles play a\nsignificant role in the exciton dynamics.",
        "positive": "Non-universal transmission phase behaviour of a large quantum dot: The electron wave function experiences a phase modification at coherent\ntransmission through a quantum dot. This transmission phase undergoes a\ncharacteristic shift of $\\pi$ when scanning through a Coulomb-blockade\nresonance. Between successive resonances either a transmission phase lapse of\n$\\pi$ or a phase plateau is theoretically expected to occur depending on the\nparity of the corresponding quantum dot states. Despite considerable\nexperimental effort, this transmission phase behaviour has remained elusive for\na large quantum dot. Here we report on transmission phase measurements across\nsuch a large quantum dot hosting hundreds of electrons. Using an original\nelectron two-path interferometer to scan the transmission phase along fourteen\nsuccessive resonances, we observe both phase lapses and plateaus. Additionally,\nwe demonstrate that quantum dot deformation alters the sequence of transmission\nphase lapses and plateaus via parity modifications of the involved quantum dot\nstates. Our findings set a milestone towards a comprehensive understanding of\nthe transmission phase of quantum dots."
    },
    {
        "anchor": "Fast electrical modulation of strong near-field interactions between\n  erbium emitters and graphene: Combining the quantum optical properties of single-photon emitters with the\nstrong near-field interactions available in nanophotonic and plasmonic systems\nis a powerful way of creating quantum manipulation and metrological\nfunctionalities. The ability to actively and dynamically modulate\nemitter-environment interactions is of particular interest in this regard.\nWhile thermal, mechanical and optical modulation have been demonstrated,\nelectrical modulation has remained an outstanding challenge. Here we realize\nfast, all-electrical modulation of the near-field interactions between a\nnanolayer of erbium emitters and graphene, by in-situ tuning the Fermi energy\nof graphene. We demonstrate strong interactions with a >1,000-fold increased\ndecay rate for 25% of the emitters, and electrically modulate these\ninteractions with frequencies up to 300 kHz - orders of magnitude faster than\nthe emitters radiative decay (100 Hz). This constitutes an enabling platform\nfor integrated quantum technologies, opening routes to quantum entanglement\ngeneration by collective plasmon emission or photon emission with controlled\nwaveform.",
        "positive": "Incident-Angle Dependence of Electromagnetic Wave Transmission through a\n  Nano-hole in a Thin Plasmonic Semiconductor Layer: This work is focussed on the role of the angle of incidence of an incoming\nelectromagnetic wave in its transmission through a subwavelength nano-hole in a\nthin semiconductor plasmonic layer. Fully detailed calculations and results are\nexhibited for $ p$- and $s$-polarizations of the incident wave for a variety of\nincident angles in the near, middle and far zones of the transmitted radiation.\nOur dyadic Green's function formulation includes both (1) the electromagnetic\nfield transmitted directly through the $ 2D $ plasmonic layer superposed with\n(2) the radiation emanating from the nano-hole. Interference fringes due to\nthis superposition are explicitly exhibited. Based on an integral equation\nformulation, this dyadic Green's function approach does not involve any appeal\nto metallic boundary conditions. It does incorporate the role of the $ 2D $\nplasmon of the semiconductor layer, which is smeared due to its lateral wave\nnumber dependence. We find that the interference fringes, which are clustered\nnear the nano-hole, flatten to a uniform level of transmission directly through\nthe sheet alone at large distances from the nano-hole. Furthermore, as the\nincident angle increases, the axis of the relatively large central transmission\nmaximum through the nano-hole follows it, accompanied by a spatial compression\nof interference fringe maxima forward of the large central transmission\nmaximum, and a spatial thinning of the fringe maxima behind it."
    },
    {
        "anchor": "Single-photon Emission from an Acoustically-driven Lateral\n  Light-emitting Diode: Single-photon sources are essential building blocks in quantum photonic\nnetworks, where quantum-mechanical properties of photons are utilised to\nachieve quantum technologies such as quantum cryptography and quantum\ncomputing. Most conventional solid-state single-photon sources are based on\nsingle emitters such as self-assembled quantum dots, which are created at\nrandom locations and require spectral filtering. These issues hinder the\nintegration of a single-photon source into a scaleable photonic quantum network\nfor applications such as on-chip photonic quantum processors. In this work,\nusing only regular lithography techniques on a conventional GaAs quantum well,\nwe realise an electrically triggered single-photon source with a GHz repetition\nrate and without the need for spectral filtering. In this device, a single\nelectron is carried in the potential minimum of a surface acoustic wave (SAW)\nand is transported to a region of holes to form an exciton. The exciton then\ndecays and creates a single photon in a lifetime of ~ 100ps. This SAW-driven\nelectroluminescence (EL) yields photon antibunching with $g^{(2)}(0) = 0.39 \\pm\n0.05$, which satisfies the common criterion for a single-photon source\n$g^{(2)}(0) < 0.5$. Furthermore, we estimate that if a photon detector receives\na SAW-driven EL signal within one SAW period, this signal has a 79%-90% chance\nof being a single photon. This work shows that a single-photon source can be\nmade by combining single-electron transport and a lateral n-i-p junction. This\napproach makes it possible to create multiple synchronised single-photon\nsources at chosen positions with photon energy determined by quantum-well\nthickness. Compared with conventional quantum-dot-based single-photon sources,\nthis device may be more suitable for an on-chip integrated photonic quantum\nnetwork.",
        "positive": "Calculation of tunnel-couplings in open gate-defined disordered quantum\n  dot systems: Quantum computation based on semiconductor electron-spin qubits requires high\ncontrol of tunnel-couplings, both across quantum dots and between the quantum\ndot and the reservoir. The tunnel-coupling to the reservoir sets the qubit\ndetection and initialization bandwidth for energy-resolved spin-to-charge\nconversion and is essential to tune single-electron transistors commonly used\nas charge detectors. Potential disorder and the increasing complexity of the\ntwo-dimensional gate-defined quantum computing devices sets high demands on the\ngate design and the voltage tuning of the tunnel barriers. We present a Green's\nformalism approach for the calculation of tunnel-couplings between a quantum\ndot and a reservoir. Our method takes into account in full detail the\ntwo-dimensional electrostatic potential of the quantum dot, the tunnel barrier\nand reservoir. A Markov approximation is only employed far away from the tunnel\nbarrier region where the density of states is sufficiently large. We calculate\nthe tunnel-coupling including potential disorder effects, which become\nincreasingly important for large-scale silicon-based spin-qubit devices.\nStudying the tunnel-couplings of a single-electron transistor in Si/SiGe as a\nshowcase, we find that charged defects are the dominant source of disorder\nleading to variations in the tunnel-coupling of four orders of magnitude."
    },
    {
        "anchor": "Aharonov-Bohm effect for a valley-polarized current in graphene: This is a numerical study of the conductance of an Aharonov-Bohm\ninterferometer in a tight-binding model of graphene. Two single-mode ballistic\npoint contacts with zigzag edges are connected by two arms of a hexagonal ring\nenclosing a magnetic flux $\\Phi$. The point contacts function as valley\nfilters, transmitting electrons from one valley of the band structure and\nreflecting electrons from the other valley. We find, in the wider rings, that\nthe magnetoconductance oscillations with the fundamental periodicity\n$\\Delta\\Phi=h/e$ are suppressed when the two valley filters have opposite\npolarity, while the second and higher harmonics are unaffected or enhanced.\nThis frequency doubling is interpreted in terms of a larger probability of\nintervalley scattering for electrons that travel several times around the ring.\nIn the narrowest rings the current is blocked for any polarity of the valley\nfilters, with small, nearly sinusoidal magnetoconductance oscillations.\nQualitatively similar results are obtained if the hexagonal ring is replaced by\na ring with an irregular boundary.",
        "positive": "Deterministic magnetization switching using lateral spin-orbit torque: Current-induced magnetization switching by spin-orbit torque (SOT) holds\nconsiderable promise for next generation ultralow-power memory and logic\napplications. In most cases, generation of spin-orbit torques has relied on an\nexternal injection of out-of-plane spin currents into the magnetic layer, while\nan external magnetic field along the electric current direction is generally\nrequired for realizing deterministic switching by SOT. Here, we report\ndeterministic current-induced SOT full magnetization switching by lateral\nspin-orbit torque in zero external magnetic field. The Pt/Co/Pt magnetic\nstructure was locally annealed by a laser track along the in-plane current\ndirection, resulting in a lateral Pt gradient within the ferromagnetic layer,\nas confirmed by microstructure and chemical composition analysis. In zero\nmagnetic field, the direction of the deterministic current-induced\nmagnetization switching depends on the location of the laser track, but shows\nno dependence on the net polarization of external out-of-plane spin currents.\nFrom the behavior under external magnetic fields, we identify two independent\nmechanisms giving rise to SOT, i.e. the lateral Pt-Co asymmetry as well as\nout-of-plane injected spin currents, where the polarization and the magnitude\nof the SOT in the former case depends on the relative location and the laser\npower of the annealing track. Our results demonstrate an efficient field-free\ndeterministic full magnetization switching scheme, without requiring\nout-of-plane spin current injection or complex external stack structures."
    },
    {
        "anchor": "The Observation of Percolation-Induced 2D Metal-Insulator Transition in\n  a Si MOSFET: By analyzing the temperature ($T$) and density ($n$) dependence of the\nmeasured conductivity ($\\sigma$) of 2D electrons in the low density\n($\\sim10^{11}$cm$^{-2}$) and temperature (0.02 - 10 K) regime of high-mobility\n(1.0 and 1.5 $\\times 10^4$ cm$^2$/Vs) Si MOSFETs, we establish that the\nputative 2D metal-insulator transition is a density-inhomogeneity driven\npercolation transition where the density-dependent conductivity vanishes as\n$\\sigma (n) \\propto (n - n_p)^p$, with the exponent $p \\sim 1.2$ being\nconsistent with a percolation transition. The `metallic' behavior of $\\sigma\n(T)$ for $n > n_p$ is shown to be well-described by a semi-classical Boltzmann\ntheory, and we observe the standard weak localization-induced negative\nmagnetoresistance behavior, as expected in a normal Fermi liquid, in the\nmetallic phase.",
        "positive": "Non-bosonic moir\u00e9 excitons: Optical excitations in moir\\'e transition metal dichalcogenide bilayers lead\nto the creation of excitons, as electron-hole bound states, that are\ngenerically considered within a Bose-Hubbard framework. Here, we demonstrate\nthat these composite particles obey an angular momentum commutation relation\nthat is generally non-bosonic. This emergent spin description of excitons\nindicates a limitation to their occupancy on each site, which is substantial in\nthe weak electron-hole binding regime. The effective exciton theory is\naccordingly a spin Hamiltonian, which further becomes a Hubbard model of\nemergent bosons subject to an occupancy constraint after a Holstein-Primakoff\ntransformation. We apply our theory to three commonly studied bilayers\n(MoSe2/WSe2, WSe2/WS2, and WSe2/MoS2) and show that in the relevant parameter\nregimes their allowed occupancies never exceed three excitons. Our systematic\ntheory provides guidelines for future research on the many-body physics of\nmoir\\'e excitons."
    },
    {
        "anchor": "Suspended Long-Lived NMR Echo in Solids: We report an observation of extremely long-lived spin states in systems of\ndipolar-coupled nuclear spins in solids. The 'suspended echo' experiment uses a\nsimple stimulated echo pulse sequence and creates non-equilibrium states which\nlive many orders of magnitude longer than the characteristic time of spin-spin\ndynamics T2. Large amounts of information can be encoded in such long-lived\nstates, stored in a form of multi-spin correlations, and subsequently retrieved\nby an application of a single 'reading' pulse.",
        "positive": "Transport in nanoscale systems: the microcanonical versus\n  grand-canonical picture: We analyse a picture of transport in which two large but finite charged\nelectrodes discharge across a nanoscale junction. We identify a functional\nwhose minimisation, within the space of all bound many-body wavefunctions,\ndefines an instantaneous steady state. We also discuss factors that favour the\nonset of steady-state conduction in such systems, make a connection with the\nnotion of entropy, and suggest a novel source of steady-state noise. Finally,\nwe prove that the true many-body total current in this closed system is given\nexactly by the one-electron total current, obtained from time-dependent\ndensity-functional theory."
    },
    {
        "anchor": "Extraordinary Phase Coherence Length in Epitaxial Halide Perovskites: Inorganic halide perovskites have emerged as a promising platform in a wide\nrange of applications from solar energy harvesting to computing, and light\nemission. The recent advent of epitaxial thin film growth of halide perovskites\nhas made it possible to investigate low-dimensional quantum electronic devices\nbased on this class of materials. This study leverages advances in vapor-phase\nepitaxy of halide perovskites to perform low-temperature magnetotransport\nmeasurements on single-domain cesium tin iodide (CsSnI$_3$) epitaxial thin\nfilms. The low-field magnetoresistance carries signatures of coherent quantum\ninterference effects and spin-orbit coupling. These weak anti-localization\nmeasurements reveal a micron-scale low-temperature phase coherence length for\ncharge carriers in this system. The results indicate that epitaxial halide\nperovskite heterostructures are a promising platform for investigating long\ncoherent quantum electronic effects and potential applications in spintronics\nand spin-orbitronics.",
        "positive": "Quantum Phase Interference in Magnetic Molecular Clusters: The Landau Zener model has recently been used to measure very small tunnel\nsplittings in molecular clusters of Fe8, which at low temperature behaves like\na nanomagnet with a spin ground state of S = 10. The observed oscillations of\nthe tunnel splittings as a function of the magnetic field applied along the\nhard anisotropy axis are due to topological quantum interference of two tunnel\npaths of opposite windings. Transitions between quantum numbers M = -S and (S -\nn), with n even or odd, revealed a parity effect which is analogous to the\nsuppression of tunnelling predicted for half integer spins. This observation is\nthe first direct evidence of the topological part of the quantum spin phase\n(Berry or Haldane phase) in a magnetic system. We show here that the quantum\ninterference can also be measured by ac susceptibility measurements in the\nthermal activated regime."
    },
    {
        "anchor": "Multiscale phonon blocking in Si phononic crystal nanostructures: In-plane thermal conduction and phonon transport in both single-crystalline\nand polycrystalline Si two-dimensional phononic crystal (PnC) nanostructures\nwere investigated at room temperature. The impact of phononic patterning on\nthermal conductivity was larger in polycrystalline Si PnCs than in\nsingle-crystalline Si PnCs. The difference in the impact is attributed to the\ndifference in the thermal phonon mean free path (MFP) distribution induced by\ngrain boundary scattering in the two materials. Grain size analysis and\nnumerical simulation using the Monte Carlo technique indicate that grain\nboundaries and phononic patterning are efficient phonon scattering mechanisms\nfor different MFP length scales. This multiscale phonon blocking structure\ncovers a large part of the broad distribution of thermal phonon MFPs and thus\nefficiently reduces thermal conduction.",
        "positive": "Rings and boxes in dissipative environments: We study a particle on a ring in presence of a dissipative Caldeira-Leggett\nenvironment and derive its response to a DC field. We find, through a 2-loop\nrenormalization group analysis, that a large dissipation parameter $\\eta$ flows\nto a fixed point $\\eta_R=\\eta_c=\\hbar/2\\pi$. We also reexamine the mapping of\nthis problem to that of the Coulomb box and show that the relaxation\nresistance, of recent interest, is quantized for large $\\eta$. For finite\n$\\eta>\\eta_c$ we find that a certain average of the relaxation resistance is\nquantized. We propose a box experiment to measure a quantized noise."
    },
    {
        "anchor": "Surface charge conductivity of topological insulator in a magnetic\n  field: effect of hexagonal warping: We investigate the influence of the hexagonal warping on the transport\nproperties of the topological insulators. We study the charge conductivity\nwithin Kubo formalism in the first Born approximation using low energy\nexpansion of the Hamiltonian near the Dirac point. The effects of disorder,\nmagnetic field and chemical potential value are analyzed in details. We found\nthat the presence of the hexagonal warping effects significantly the\nconductivity of the topological insulator. In particular, it gives rise to the\ngrowth of the longitudinal conductivity with the increase of the disorder and\nanisotropic anomalous in-plane magnetoresistance. The hexagonal warping also\naffects the quantum anomalous Hall effect and anomalous out-of-plane\nmagnetoresistance. The obtained results are consistent with the experimental\ndata.",
        "positive": "Scroll configurations of carbon nanoribbons: Carbon nanoscroll is a unique topologically open configuration of graphene\nnanoribbon possessing outstanding properties and application perspectives due\nto its morphology. However molecular dynamics study of nanoscrolls with more\nthan a few coils is limited by computational power. Here, we propose a simple\nmodel of the molecular chain moving in the plane, allowing to describe the\nfolded and rolled packaging of long graphene nanoribbons. The model is used to\ndescribe a set of possible stationary states and the low-frequency oscillation\nmodes of isolated single-layer nanoribbon scrolls as the function of the\nnanoribbon length. Possible conformational changes of scrolls due to thermal\nfluctuations are analyzed and their thermal stability is examined. Using the\nfull-atomic model, frequency spectrum of thermal vibrations is calculated for\nthe scroll and compared to that of the flat nanoribbon. It is shown that the\ndensity of phonon states of the scroll differs from the one of the flat\nnanoribbon only in the low (omega<100 cm-1) and high (omega>1450 cm-1)\nfrequency ranges. Finally, the linear thermal expansion coefficient for the\nscroll outer radius is calculated from the long-term dynamics with the help of\nthe developed planar chain model. The scrolls demonstrate anomalously high\ncoefficient of thermal expansion and this property can find new applications."
    },
    {
        "anchor": "Subgap resonant quasiparticle transport in normal-superconductor quantum\n  dot devices: We report thermally activated transport resonances for biases below the\nsuperconducting energy gap in a carbon nanotube (CNT) quantum dot (QD) device\nwith a superconducting Pb and a normal metal contact. These resonances are due\nto the superconductor's finite quasi-particle population at elevated\ntemperatures and can only be observed when the QD life-time broadening is\nconsiderably smaller than the gap. This condition is fulfilled in our QD\ndevices with optimized Pd/Pb/In multi-layer contacts, which result in\nreproducibly large and \"clean\" superconducting transport gaps with a strong\nconductance suppression for subgap biases. We show that these gaps close\nmonotonically with increasing magnetic field and temperature. The accurate\ndescription of the subgap resonances by a simple resonant tunneling model\nillustrates the ideal characteristics of the reported Pb contacts and gives an\nalternative access to the tunnel coupling strengths in a QD.",
        "positive": "Tunneling into 1D and quasi-1D conductors and Luttinger-liquid behavior: The paper addresses the problem whether and how it is possible to detect the\nLuttinger-liquid behavior from the $IV$ curves for tunneling to 1D or quasi-1D\nconductors. The power-law non-ohmic $IV$ curve, which is usually considered as\na manifestation of the Luttinger-liquid behavior, can be also deduced from the\ntheory of the Coulomb blockaded junction between 3D conductors affected by the\nenvironment effect. In both approaches the power-law exponents are determined\nby the ratio of the impedance of an effective electric circuit to the quantum\nresistance. Though two approaches predict different power-law exponents\n(because of a different choice of effective circuits), the difference becomes\nnegligible for a large number of conductance channels."
    },
    {
        "anchor": "Anatase TiO$_2$ Nanowires Functionalized by Organic Sensitizers for\n  Solar Cells : A Screened Coulomb Hybrid Density Functional Study: The adsorption of two different organic molecules cyanidin glucoside\n(C$_{21}$O$_{11}$H$_{20}$) and TA-St-CA on anatase (101) and (001) nanowires\nhave been investigated using the standard and the range separated hybrid\ndensity functional theory calculations. The electronic structures and optical\nspectra of resulting dye--nanowire combined systems show distinct features for\nthese types of photochromophores. The lowest unoccupied molecular orbital of\nthe natural dye cyanidin glucoside is located below the conduction band of the\nsemiconductor while, in the case of TA-St-CA, it resonates with the states\ninside the conduction band. The wide-bandgap anatase nanowires can be\nfunctionalized for solar cells through electron-hole generation and subsequent\ncharge injection by these dye sensitizers. The intermolecular charge transfer\ncharacter of Donor-$\\pi$-Acceptor type dye TA-St-CA is substantially modified\nby its adsorption on TiO$_2$ surfaces. Cyanidin glucoside exhibits relatively\nstronger anchoring on the nanowires through its hydroxyl groups. The atomic\nstructures of dye--nanowire systems re-optimized with the inclusion of\nnonlinear solvation effects showed that the binding strengths of both dyes\nremain moderate even in ionic solutions.",
        "positive": "Molecular Plasmonics: strong coupling at the low molecular density limit: We study the strong coupling between the molecular excited state and the\nplasmonic modes of silver hole arrays with a resonant frequency very close to\nthe asymptotic line of the plasmonic dispersion relation, at the nonlinear\nregime. We demonstrate that the strong coupling regime can be achieved between\nthe two sub-systems at low molecular densities with negligible damping of the\nelectromagnetic field. Our results are supported by rigorous numerical\nsimulations showing that the strong coupling is observed when the molecular\ntransition lies within the nonlinear regime of the dispersion relation rather\nthan the linear regime."
    },
    {
        "anchor": "Effective Action Studies of Quantum Hall Spin Textures: We report on analytic and numerical studies of spin textures in quantum Hall\nsystems using a long-wavelength effective action for the magnetic degrees of\nfreedom derived previously. The majority of our results concern skyrmions or\nsolitons of this action. We have constructed approximate analytic solutions for\nskyrmions of arbitrary topological and electric charge and derived expressions\nfor their energies and charge and spin radii. We describe a combined\nshooting/relaxational technique for numerical determination of the skyrmion\nprofiles and present results that compare favorably with the analytic treatment\nas well as with Hartree-Fock studies of these objects. In addition, we describe\na treatment of textures at the edges of quantum Hall systems within this\napproach and provide details not reported previously.",
        "positive": "Near-IR photoluminescence from Si/Ge nanowire grown silicon wafers:\n  effect of HF treatment: We present the room temperature (RT) near-infrared (NIR) photoluminescence\n(PL) properties of Si/Ge nanowire (NW) grown silicon wafers which were treated\nby vapor of HF:HNO3 chemical mixture. This treatment activates or enhances the\nPL intensity at NIR region ranging from 1000 nm to 1800 nm. The PL consists of\na silicon band-edge emission and a broad composite band which was centered at\naround 1400-1600 nm. The treatment modifies the wafer surface particularly at\ndefect sites particularly pits around NWs and NW surfaces by etching and\noxidation of Si and Ge. This process can induce spatial confinement of carriers\nwhere band-to-band (BB) emission is the dominant property in Si capped strained\nSi/Ge NW grown wafers. Strong signals were observed at sub-band gap energies in\nGe capped Si/Ge NW grown wafers. It was found that NIR PL is a competitive\nproperty between the Si BB transition and deep-level emission which is mainly\nattributable to Si related defects, Ge dots and strained Ge layers. The\nenhancement in BB and deep-level PL was discussed in terms of strain, oxygen\nrelated defects, dots formation and carrier confinement effects. The results\ndemonstrate the effectiveness of this method in enhancing and tuning NIR PL\nproperties for possible applications."
    },
    {
        "anchor": "Preparing local strain patterns in graphene by atomic force microscope\n  based indentation: Patterning graphene into various mesoscopic devices such as nanoribbons,\nquantum dots, etc. by lithographic techniques has enabled the guiding and\nmanipulation of graphene's Dirac-type charge carriers. Graphene, with\nwell-defined strain patterns, holds promise of similarly rich physics while\navoiding the problems created by the hard to control edge configuration of\nlithographically prepared devices. To engineer the properties of graphene via\nmechanical deformation, versatile new techniques are needed to pattern strain\nprofiles in a controlled manner. Here we present a process by which strain can\nbe created in substrate supported graphene layers. Our atomic force\nmicroscope-based technique opens up new possibilities in tailoring the\nproperties of graphene using mechanical strain.",
        "positive": "Momentum relaxation effects in 2D-Xene field effect device structures: We analyze the electric field driven topological field effect transition on\n2D-xene materials with the addition of momentum relaxation effects, in order to\naccount for dephasing processes. The topological field effect transition\nbetween the quantum spin Hall phase and the quantum valley Hall phase is\nanalyzed in detail using the Keldysh non-equilibrium Green's function technique\nwith the inclusion of momentum and phase relaxation, within the self-consistent\nBorn approximation. Details of the transition with applied electric field are\nelucidated for the ON-OFF characteristics with emphasis on the transport\nproperties along with the tomography of the current carrying edge states. We\nnote that for moderate momentum relaxation, the current carrying quantum spin\nHall edge states are still pristine and show moderate decay with propagation.\nTo facilitate our analysis, we introduce two metrics in our calculations, the\ncoherent transmission and the effective transmission. In elucidating the\nphysics clearly, we show that the effective transmission, which is derived\nrigorously from the quantum mechanical current operator is indeed the right\nquantity to analyze topological stability against dephasing. Exploring further,\nwe show that the insulating quantum valley Hall phase, as a result of dephasing\ncarries band-tails which potentially activates parasitic OFF currents, thereby\ndegrading the ON-OFF ratios. Our analysis sets the stage for realistic modeling\nof topological field effect devices for various applications, with the\ninclusion of scattering effects and analyzing their role in the optimization of\nthe device performance."
    },
    {
        "anchor": "Searching for thermal signatures of persistent currents in normal metal\n  rings: We introduce a calorimetric approach to probe persistent currents in normal\nmetal rings. The heat capacity of a large ensemble of silver rings is measured\nby nanocalorimetry under a varying magnetic field at different temperatures (60\nmK, 100 mK and 150 mK). Periodic oscillations versus magnetic field are\ndetected in the phase signal of the temperature oscillations, though not in the\namplitude (both of them directly linked to the heat capacity). The period of\nthese oscillations ($\\Phi_0/2$, with $\\Phi_0 = h/e$ the magnetic flux quantum)\nand their evolution with temperature are in agreement with theoretical\npredictions. In contrast, the amplitude of the corresponding heat capacity\noscillations (several $k_{\\mathrm{B}}$) is two orders of magnitude larger than\npredicted by theory.",
        "positive": "Steady States of a Microwave Irradiated Quantum Hall Gas: We consider effects of a long-wavelength disorder potential on the Zero\nConductance State (ZCS) of the microwave-irradiated 2D electron gas. Assuming a\nuniform Hall conductivity, we construct a Lyapunov functional and derive\nstability conditions on the domain structure of the photo-generated fields. We\nsolve the resulting equations for a general one-dimensional and certain\ntwo-dimensional disorder potentials, and find non-zero conductances,\nphoto-voltages, and circulating dissipative currents. In contrast, weak white\nnoise disorder does not destroy the ZCS, but induces mesoscopic current\nfluctuations."
    },
    {
        "anchor": "Why a magnetized quantum wire can act as an active laser medium: The fundamental issues associated with the magnetoplasmon excitations are\ninvestigated in a quantum wire characterized by a confining harmonic potential\nand subjected to a perpendicular magnetic field. We embark on the\ncharge-density excitations in a two-subband model within the framework of\nBohm-Pines' random-phase approximation. Essentially, the focus of our study is\nthe intersubband (magnetoroton) collective excitation which changes the sign of\nits group velocity twice before merging with the respective single-particle\ncontinuum. The computation of the gain coefficient suggests an interesting and\nimportant application: the electronic device based on such magnetoroton modes\ncan act as an {\\it active} laser medium.",
        "positive": "Hopf-link multi-Weyl-loop topological semimetals: We construct a generic two-band model which can describe topological Weyl\nsemimetals with multiple closed Weyl loops. All the existing multi-Weyl-loop\nsemimetals including the nodal-net, or nodal-chain and Hopf-link states can be\nexamined within one same framework. Based on a two-loop model, the\ncorresponding drum-head surface states for these topologically different bulk\nstates are studied and compared with each other. The connection of our model\nwith Hopf insulators is also discussed. Furthermore, to identify experimentally\nthese topologically different Weyl semimetal states, especially distinguish the\nHopf-link from unlinked ones, we also investigate their Landau levels. It is\nfound that the Hopf-link state can be characterized by the existence of a\nquadruply degenerate zero-energy Landau band, regardless of the direction of\nthe magnetic field."
    },
    {
        "anchor": "Friedel oscillations, impurity scattering and temperature dependence of\n  resistivity in graphene: We show that Friedel oscillations (FO) in grapehene are strongly affected by\nthe chirality of electrons in this material. In particular, the FO of the\ncharge density around an impurity show a faster, $1/r^3$, decay than in\nconventional 2D electron systems and do not contribute to a linear\ntemperature-dependent correction to the resistivity. In contrast, the FO of the\nexchange field which surrounds atomically sharp defects breaking the hexagonal\nsymmetry of the honeycomb lattice lead to a negative linear T dependence of the\nresistivity.",
        "positive": "Unconventional Sequence of Fractional Quantum Hall States in Suspended\n  Graphene: Interactions among electrons can give rise to striking collective phenomena\nwhen the kinetic energy of charge carriers is suppressed. One example is the\nfractional quantum Hall effect, in which correlations between electrons moving\nin two dimensions under the influence of a strong magnetic field generate\nexcitations with fractional charge. Graphene provides a platform to study\nunique many-body effects due to its massless chiral charge carriers and the\nfourfold degeneracy that arises from their spin and valley degrees of freedom.\nHere we report local electronic compressibility measurements of a suspended\ngraphene flake performed using a scanning single-electron transistor. Between\nLandau level filling v = 0 and 1, we observe incompressible fractional quantum\nHall states that follow the standard composite fermion sequence v = p/(2p \\pm\n1) for all integer p \\leq 4. In contrast, incompressible behavior occurs only\nat v = 4/3, 8/5, 10/7 and 14/9 between v = 1 and 2. These fractions correspond\nto a subset of the standard composite fermion sequence involving only even\nnumerators, suggesting a robust underlying symmetry. We extract the energy gaps\nassociated with each fractional quantum Hall state as a function of magnetic\nfield. The states at v = 1/3, 2/3, 4/3 and 8/5 are the strongest at low field,\nand persist below 1.5 T. The unusual sequence of incompressible states provides\ninsight into the interplay between electronic correlations and SU(4) symmetry\nin graphene."
    },
    {
        "anchor": "Aharonov-Bohm conductance of a disordered single-channel quantum ring: We study the effect of weak disorder on tunneling conductance of a\nsingle-channel quantum ring threaded by magnetic flux. We assume that\ntemperature is higher than the level spacing in the ring and smaller than the\nFermi energy. In the absence of disorder, the conductance shows sharp dips\n(antiresonances) as a function of magnetic flux. We discuss different types of\ndisorder and find that the short-range disorder broadens antiresonances, while\nthe long-range one leads to arising of additional resonant dips. We demonstrate\nthat the resonant dips have essentially non-Lorentzian shape. The results are\ngeneralized to account for the spin-orbit interaction which leads to splitting\nof the disorder-broadened resonant dips, and consequently to coexisting of two\ntypes of oscillations (both having the form of sharp dips): Aharonov-Bohm\noscillations with magnetic flux and Aharonov-Casher oscillations with the\nstrength of the spin-orbit coupling. We also discuss the effect of the Zeeman\ncoupling.",
        "positive": "Determining the spin-orbit coupling via spin-polarized spectroscopy of\n  magnetic impurities: We study the spin-resolved spectral properties of the impurity states\nassociated to the presence of magnetic impurities in two-dimensional, as well\nas one-dimensional systems with Rashba spin-orbit coupling. We focus on Shiba\nbound states in superconducting materials, as well as on impurity states in\nmetallic systems. Using a combination of a numerical T-matrix approximation and\na direct analytical calculation of the bound state wave function, we compute\nthe local density of states (LDOS) together with its Fourier transform (FT). We\nfind that the FT of the spin-polarized LDOS, a quantity accessible via\nspin-polarized STM, allows to accurately extract the strength of the spin-orbit\ncoupling. Also we confirm that the presence of magnetic impurities is strictly\nnecessary for such measurement, and that non-spin-polarized experiments cannot\nhave access to the value of the spin-orbit coupling."
    },
    {
        "anchor": "Field Quantization for Radiative Decay of Plasmons in Finite and\n  Infinite Geometries: We investigate field quantization in high-curvature geometries. The models\nand calculations can help with understanding the elastic and inelastic\nscattering of photons and electrons in nanostructures and probe-like metallic\ndomains. The results find important applications in high-resolution photonic\nand electronic modalities of scanning probe microscopy, nano-optics,\nplasmonics, and quantum sensing. Quasistatic formulation, leading to\nnonretarded quantities, is employed and justified on the basis of the\nnanoscale, here subwavelength, dimensions of the considered domains of\ninterest. Within the quasistatic framework, we represent the nanostructure\nmaterial domains with frequency-dependent dielectric functions. Quantities\nassociated with the normal modes of the electronic systems, the nonretarded\nplasmon dispersion relations, eigenmodes, and fields are then calculated for\nseveral geometric entities of use in nanoscience and nanotechnology. From the\nclassical energy of the charge density oscillations in the modeled\nnanoparticle, we then derive the Hamiltonian of the system, which is used for\nquantization. The quantized plasmon field is obtained and, employing an\ninteraction Hamiltonian derived from the first-order perturbation theory within\nthe hydrodynamic model of the electron gas, we obtain an analytical expression\nfor the radiative decay rate of the plasmons. The established treatment is\napplied to multiple geometries to investigate the quantized charge density\noscillations on their bounding surfaces. Specifically, using one sheet of a\ntwo-sheeted hyperboloid of revolution, paraboloid of revolution, and\ncylindrical domains, all with one infinite dimension, and the finite spheroidal\nand toroidal domains are treated. ...",
        "positive": "Generation of entanglement between quantum dot molecule with the\n  presence of phonon effects in a voltage-controlled junction: We investigate the generation of entanglement through a quantum dot molecule\nunder the influence of vibrational phonon modes in a bias voltage junction. The\nmolecular quantum dot system is realized by coupled quantum dots inside a\nsuspended carbon nanotube. We consider the dynamical entanglement as a function\nof bias voltage and temperature by taking into account the electron-phonon\ninteraction. In order to generate the robust entanglement between quantum dots\nand preserve it to reach the maximal achievable amount steadily, we introduce\nan asymmetric coupling protocol and apply the easy tunable bias voltage-driven\nfield. For an oscillating bias voltage, the time-varying entanglement can\nperiodically reach the maximum revival. In thermal entanglement dynamics, the\nphenomena of thermal entanglement degradation and thermal entanglement revival\nare observed which are intensively affected by the strength of phonon\ndecoherence. The revival of entanglement shows a larger value for a higher\nphonon coupling."
    },
    {
        "anchor": "Nondissipative Drag Conductance as a Topological Quantum Number: We show in this paper that the boundary condition averaged nondissipative\ndrag conductance of two coupled mesoscopic rings with no tunneling, evaluated\nin a particular many-particle eigenstate, is a topological invariant\ncharacterized by a Chern integer. Physical implications of this observation are\ndiscussed.",
        "positive": "Pauli blockade microscopy of quantum dots: We propose a spin-sensitive scanning probe microscopy experiment on double\nquantum dots in Pauli blockade conditions. Electric spin resonance is induced\nby an AC voltage applied to the scanning gate which induces lifting of the\nPauli blockade of the current. The stationary Hamiltonian eigenstates are used\nas a basis for description of the spin dynamics with the AC potential of the\nprobe. For the two-electron system we evaluate the transitions rates from\ntriplet $\\mathrm{T}_+$ state to singlet $\\mathrm{S}$ or triplet $\\mathrm{T}_0$\nstates, i.e. to conditions in which the Pauli blockade of the current is\nlifted. The rates of the spin-flip transitions are consistent with the\ntransition matrix elements and strongly dependent on the tip position. Probing\nthe spin densities and identification of the final transition state are\ndiscussed."
    },
    {
        "anchor": "Atomic-scale defects restricting structural superlubricity: Ab initio\n  study study on the example of the twisted graphene bilayer: The potential energy surface (PES) of interlayer interaction of twisted\nbilayer graphene with vacancies in one of the layers is investigated via\ndensity functional theory (DFT) calculations with van der Waals corrections.\nThese calculations give a non-negligible magnitude of PES corrugation of 28 meV\nper vacancy and barriers for relative sliding of the layers of 7 - 8 meV per\nvacancy for the moir\\'e pattern with coprime indices (2,1) (twist angle\n21.8$^\\circ$). At the same time, using the semiempirical potential fitted to\nthe DFT results, we confirm that twisted bilayer graphene without defects\nexhibits superlubricity for the same moir\\'e pattern and the magnitude of PES\ncorrugation for the infinite bilayer is below the calculation accuracy. Our\nresults imply that atomic-scale defects restrict the superlubricity of 2D\nlayers and can determine static and dynamic tribological properties of these\nlayers in a superlubric state. We also analyze computationally cheap approaches\nthat can be used for modeling of tribological behavior of large-scale systems\nwith defects. The adequacy of using state-of-the-art semiempirical potentials\nfor interlayer interaction and approximations based on the first spatial\nFourier harmonics for the description of interaction between graphene layers\nwith defects is discussed.",
        "positive": "Electrically Controlled Two-Dimensional Electron-Hole Fluids: We study the electronic properties of dual-gated electron-hole bilayers in\nwhich the two layers are separated by a perfectly opaque tunnel barrier.\nCombining an electrostatic and thermodynamic analysis with mean-field theory\nestimates of interacting system chemical potentials, we explain the dependence\nof the electron and hole densities on the two gate voltages. Because chemical\npotential jumps occur for both electrons and holes at neutrality, there is a\nfinite area in gate voltage parameter space over which electron and hole\ndensities are equal. In that regime the electron-hole pair density depends only\non the sum of the two gate voltages. We are able to explain a recent\nexperimental study of electrically controlled bilayers by allowing for\ninterlayer tunneling and using a non-equilibrium steady-state transport\npicture."
    },
    {
        "anchor": "Electron-elastic-wave interaction in a two-dimensional topological\n  insulator: The interaction between an electron and an elastic wave is investigated for\nHgTe and InAs-GaSb quantum wells. The well-known Bernevig-Hughes-Zhang model,\ni.e., the $4\\times 4$ model for a two-dimensional (2D) topological insulator\n(TI), is extended to include terms that describe the coupling between the\nelectron and the elastic wave. The influence of this interaction on the\ntransport properties of the 2DTI and of the edge states is discussed. As the\nelectron-like and hole-like carriers interact with the elastic wave differently\ndue to the cubic symmetry of the 2DTI, one may utilize the elastic wave to\ntune/control the transport property of charge carriers in the 2DTI. The\nextended 2DTI model also provides the possibility to investigate the\nbackscattering of edge states of a 2DTI more realistically.",
        "positive": "Mechanisms of Manganese-Assisted Nonradiative Recombination in\n  Cd(Mn)Se/Zn(Mn)Se Quantum Dots: Mechanisms of nonradiative recombination of electron-hole complexes in\nCd(Mn)Se/Zn(Mn)Se quantum dots accompanied by interconfigurational excitations\nof Mn$^{2+}$ ions are analyzed within the framework of single electron model of\ndeep {\\it 3d}-levels in semiconductors. In addition to the mechanisms caused by\nCoulomb and exchange interactions, which are related because of the Pauli\nprinciple, another mechanism due to {\\it sp-d} mixing is considered. It is\nshown that the Coulomb mechanism reduces to long-range dipole-dipole energy\ntransfer from photoexcited quantum dots to Mn$^{2+}$ ions. The recombination\ndue to the Coulomb mechanism is allowed for any states of Mn$^{2+}$ ions and\n{\\it e-h} complexes. In contrast, short-range exchange and ${\\it sp-d}$\nrecombinations are subject to spin selection rules, which are the result of\nstrong {\\it lh-hh} splitting of hole states in quantum dots. Estimates show\nthat efficiency of the {\\it sp-d} mechanism can considerably exceed that of the\nCoulomb mechanism. The phonon-assisted recombination and processes involving\nupper excited states of Mn$^{2+}$ ions are studied. The increase in PL\nintensity of an ensemble of quantum dots in a magnetic field perpendicular to\nthe sample growth plane observed earlier is analyzed as a possible\nmanifestation of the spin-dependent recombination."
    },
    {
        "anchor": "Emission spectrum of the driven nonlinear oscillator: Motivated by recent \"circuit QED\" experiments we investigate the noise\nproperties of coherently driven nonlinear resonators. By using Josephson\njunctions in superconducting circuits, strong nonlinearities can be engineered,\nwhich lead to the appearance of pronounced effects already for a low number of\nphotons in the resonator. Based on a master equation approach we determine the\nemission spectrum and observe for typical circuit QED parameters, in addition\nto the primary Raman-type peaks, second-order peaks. These peaks describe\nhigher harmonics in the slow noise-induced fluctuations of the oscillation\namplitude of the resonator and provide a clear signature of the nonlinear\nnature of the system.",
        "positive": "Current oscillations in Vanadium Dioxide: evidence for electrically\n  triggered percolation avalanches: In this work, we experimentally and theoretically explore voltage controlled\noscillations occurring in micro-beams of vanadium dioxide. These oscillations\nare a result of the reversible insulator to metal phase transition in vanadium\ndioxide. Examining the structure of the observed oscillations in detail, we\npropose a modified percolative-avalanche model which allows for\nvoltage-triggering. This model captures the periodicity and waveshape of the\noscillations as well as several other key features. Importantly, our modeling\nshows that while temperature plays a critical role in the vanadium dioxide\nphase transition, electrically induced heating cannot act as the primary\ninstigator of the oscillations in this configuration. This realization leads us\nto identify electric field as the most likely candidate for driving the phase\ntransition."
    },
    {
        "anchor": "Dynamics and Hall-edge-state mixing of localized electrons in a\n  two-channel Mach-Zehnder interferometer: We present a numerical study of a multichannel electronic Mach-Zehnder\ninterferometer, based on magnetically-driven non-interacting edge states. The\nelectron path is defined by a full-scale potential landscape on the\ntwo-dimensional electron gas at filling factor two, assuming initially only the\nfirst Landau level as filled. We tailor the two beam splitters with 50%\ninterchannel mixing and measure Aharonov-Bohm oscillations in the transmission\nprobability of the second channel. We perform time-dependent simulations by\nsolving the electron Schroedinger equation through a parallel implementation of\nthe split-step Fourier method and we describe the charge-carrier wave function\nas a Gaussian wave packet of edge states. We finally develop a simplified\ntheoretical model to explain the features observed in the transmission\nprobability and propose possible strategies to optimize gate performances.",
        "positive": "Entropic Effects of Thermal Rippling on van der Waals Interactions\n  between Monolayer Graphene and a Rigid Substrate: Graphene monolayer, with extremely low flexural stiffness, displays\nspontaneous rippling due to thermal fluctuations at a finite temperature. When\na graphene membrane is placed on a solid substrate, the adhesive interactions\nbetween graphene and the substrate could considerably suppress thermal\nrippling. On the other hand, the statistical nature of thermal rippling adds an\nentropic contribution to the graphene-substrate interactions. In this paper we\npresent a statistical mechanics analysis on thermal rippling of monolayer\ngraphene supported on a rigid substrate, assuming a generic form of van der\nWaals interactions between graphene and substrate at T = 0 K. The rippling\namplitude, the equilibrium average separation, and the average interaction\nenergy are predicted simultaneously and compared with molecular dynamics (MD)\nsimulations. While the amplitude of thermal rippling is reduced by adhesive\ninteractions, the entropic contribution leads to an effective repulsion. As a\nresult, the equilibrium average separation increases and the effective adhesion\nenergy decreases with increasing temperature. Moreover, the effect of a biaxial\npre-strain in graphene is considered, and a buckling instability is predicted\nat a critical compressive strain that depends on both the temperature and the\nadhesive interactions. Limited by the harmonic approximations, the theoretical\npredictions agree with MD simulations only for relatively small rippling\namplitudes but can be extended to account for the anharmonic effects."
    },
    {
        "anchor": "Coherent control of an effective two-level system in a non-Markovian\n  biomolecular environment: We investigate the quantum coherent dynamics of an externally driven\neffective two-level system subjected to a slow Ohmic environment characteristic\nof biomolecular protein-solvent reservoirs in photosynthetic light harvesting\ncomplexes. By means of the numerically exact quasi adiabatic propagator path\nintegral (QUAPI) method we are able to include non-Markovian features of the\nenvironment and show the dependence of the quantum coherence on the\ncharacteristic bath cut-off frequency omega_c as well as on the driving\nfrequency omega_l and the field amplitude A. Our calculations extend from the\nweak coupling regime to the incoherent strong coupling regime. In the latter\ncase, we find evidence for a resonant behaviour, beyond the expected behaviour,\nwhen the reorganization energy E_r coincides with the driving frequency.\nMoreover, we investigate how the coherent destruction of tunneling within the\ntwo-level system is influenced by the non-Markovian environment.",
        "positive": "Measurement of the infrared transmission through a single doped GaAs\n  quantum well in an external magnetic field: Evidence for polaron effects: Precise absolute far-infra-red magneto-transmission experiments have been\nperformed in magnetic fields up to 33 T on a series of single GaAs quantum\nwells doped at different levels. The transmission spectra have been simulated\nwith a multilayer dielectric model. The imaginary part of the optical response\nfunction which reveals new singular features related to the electron-phonon\ninteractions has been extracted. In addition to the expected polaronic effects\ndue to the longitudinal optical (LO) phonon of GaAs, a new kind of carrier\nconcentration dependent interaction with interface phonons is observed. A\nsimple physical model is used to try to quantify these interactions and explore\ntheir origin."
    },
    {
        "anchor": "Single atom laser in normal-superconductor quantum dots: We study a single-level quantum dot strongly coupled to a superconducting\nlead and tunnel-coupled to a normal electrode which can exchange energy with a\nsingle-mode resonator. We show that a such system can sustain lasing\ncharacterized by a sub-Poissonian Fock-state distribution of the resonator. The\nlasing regime is clearly identifiable in the subgap transport regime: in the\nresonant case, the current is pinned to the maximum value achievable in this\nhybrid nanostructure.",
        "positive": "Integrated superconducting detectors on semiconductors for quantum\n  optics applications: Semiconductor quantum photonic circuits can be used to efficiently generate,\nmanipulate, route and exploit non-classical states of light for distributed\nphoton based quantum information technologies. In this article, we review our\nrecent achievements on the growth, nanofabrication and integration of\nhigh-quality, superconducting niobium nitride thin films on optically active,\nsemiconducting GaAs substrates and their patterning to realise highly efficient\nand ultrafast superconducting detectors on semiconductor nanomaterials\ncontaining quantum dots. Our state-of-the-art detectors reach external\ndetection quantum efficiencies up to 20% for ~4nm thin films and single photon\ntiming resolutions <72ps. We discuss the integration of such detectors into\nquantum dot loaded, semiconductor ridge waveguides, resulting in the on-chip,\ntime-resolved detection of quantum dot luminescence. Furthermore, a prototype\nquantum optical circuit is demonstrated that enabled the on-chip generation of\nresonance fluorescence from an individual InGaAs quantum dot, with a line width\n<15 $\\mu$eV displaced by 1mm from the superconducting detector on the very same\nsemiconductor chip. Thus, all key components required for prototype quantum\nphotonic circuits with sources, optical components and detectors on the same\nchip are reported."
    },
    {
        "anchor": "Observation of Quantum Asymmetry in an Aharonov-Bohm Ring: We have investigated the Aharonov-Bohm effect in a one-dimensional\nGaAs/GaAlAs ring at low magnetic fields. The oscillatory magnetoconductance of\nthese systems are for the first time systematically studied as a function of\ndensity. We observe phase-shifts of $\\pi$ in the magnetoconductance\noscillations, and halving of the fundamental $h/e$ period, as the density is\nvaried. Theoretically we find agreement with the experiment, by introducing an\nasymmetry between the two arms of the ring.",
        "positive": "Semiclassical transport in nearly symmetric quantum dots I:\n  symmetry-breaking in the dot: We apply the semiclassical theory of transport to quantum dots with exact and\napproximate spatial symmetries; left-right mirror symmetry, up-down mirror\nsymmetry, inversion symmetry or four-fold symmetry. In this work - the first of\na pair of articles - we consider (a) perfectly symmetric dots and (b) nearly\nsymmetric dots in which the symmetry is broken by the dot's internal dynamics.\nThe second article addresses symmetry-breaking by displacement of the leads.\nUsing semiclassics, we identify the origin of the symmetry-induced interference\neffects that contribute to weak-localization corrections and universal\nconductance fluctuations. For perfect spatial symmetry, we recover results\npreviously found using the random-matrix theory conjecture. We then go on to\nshow how the results are affected by asymmetries in the dot, magnetic fields\nand decoherence. In particular, the symmetry-asymmetry crossover is found to be\ndescribed by a universal dependence on an asymmetry parameter $\\gamma_{asym}$.\nHowever, the form of this parameter is very different depending on how the dot\nis deformed away from spatial symmetry. Symmetry-induced interference effects\nare completely destroyed when the dot's boundary is globally deformed by less\nthan an electron wavelength. In contrast, these effects are only reduced by a\nfinite amount when a part of the dot's boundary smaller than a lead-width is\ndeformed an arbitrarily large distance."
    },
    {
        "anchor": "Acoustic waves generated by the spin precession: We study generation of acoustic waves by a precessing spin of a nanoparticle\ndeposited on the surface of a solid. Our approach elucidates macroscopic\ndynamics of the Einstein - de Haas effect. It is based upon solution of\nparameter-free equations of motion mandated by the conservation of the total\nangular momentum: spin + mechanical. We show that the amplitude of the acoustic\nwaves generated by the spin precession may be sufficient for detection by a\ntunneling electron microscope.",
        "positive": "Dependence of the 0.7 anomaly on the curvature of the potential barrier\n  in quantum wires: Ninety eight one-dimensional channels defined using split gates fabricated on\na GaAs/AlGaAs heterostructure are measured during one cooldown at 1.4 K. The\ndevices are arranged in an array on a single chip, and individually addressed\nusing a multiplexing technique. The anomalous conductance feature known as the\n\"0.7 structure\" is studied using statistical techniques. The ensemble of data\nshow that the 0.7 anomaly becomes more pronounced and occurs at lower values as\nthe curvature of the potential barrier in the transport direction decreases.\nThis corresponds to an increase in the effective length of the device. The 0.7\nanomaly is not strongly influenced by other properties of the conductance\nrelated to density. The curvature of the potential barrier appears to be the\nprimary factor governing the shape of the 0.7 structure at a given T and B."
    },
    {
        "anchor": "Enhancement of spin to charge conversion efficiency at the topological\n  surface state by inserting normal metal spacer layer in the topological\n  insulator based heterostructure: We report efficient spin to charge conversion (SCC) in the topological\ninsulator (TI) based heterostructure ($BiSbTe_{1.5}Se_{1.5}/Cu/Ni_{80}Fe_{20}$)\nby using spin-pumping technique where $BiSbTe_{1.5}Se_{1.5}$ is the TI and\n$Ni_{80}Fe_{20}$ is the ferromagnetic layer. The SCC, characterized by inverse\nEdelstein effect length ($\\lambda_{IEE}$) in the TI material gets altered with\nan intervening Copper (Cu) layer and it depends on the interlayer thickness.\nThe introduction of Cu layer at the interface of TI and ferromagnetic metal\n(FM) provides a new degree of freedom for tuning the SCC efficiency of the\ntopological surface states. The significant enhancement of the measured\nspin-pumping voltage and the linewidth of ferromagnetic resonance (FMR)\nabsorption spectra due to the insertion of Cu layer at the interface indicates\na reduction in spin memory loss at the interface that resulted from the\npresence of exchange coupling between the surface states of TI and the local\nmoments of ferromagnetic metal. The temperature dependence (from 8K to 300K) of\nthe evaluated $\\lambda_{IEE}$ data for all the trilayer systems, TI/Cu/FM with\ndifferent Cu thickness confirms the effect of exchange coupling between the TI\nand FM layer on the spin to charge conversion efficiency of the topological\nsurface state.",
        "positive": "Inertial spin waves in ferromagnets and antiferromagnets: Inertial effects in spin dynamics are theoretically predicted to emerge at\nultrashort time scales, but their experimental signatures are often ambiguous.\nHere, we calculate the spin-wave spectrum in ferromagnets and two-sublattice\nantiferromagnets in the presence of inertial effects. It is shown how\nprecession and nutation spin waves hybridize with each other, leading to the\nrenormalization of the frequencies, the group velocities, the effective\ngyromagnetic ratios and the effective damping parameters. Possible ways of\ndistinguishing between the signatures of inertial dynamics and similar effects\nexplainable within conventional models are discussed."
    },
    {
        "anchor": "Bose-Einstein condensation of trapped polaritons in 2D electron-hole\n  systems in a high magnetic field: The Bose-Einstein condensation (BEC) of magnetoexcitonic polaritons in\ntwo-dimensional (2D) electron-hole system embedded in a semiconductor\nmicrocavity in a high magnetic field $B$ is predicted. There are two physical\nrealizations of 2D electron-hole system under consideration: a graphene layer\nand quantum well (QW). A 2D gas of magnetoexcitonic polaritons is considered in\na planar harmonic potential trap. Two possible physical realizations of this\ntrapping potential are assumed: inhomogeneous local stress or harmonic electric\nfield potential applied to excitons and a parabolic shape of the semiconductor\ncavity causing the trapping of microcavity photons. The effective Hamiltonian\nof the ideal gas of cavity polaritons in a QW and graphene in a high magnetic\nfield and the BEC temperature as functions of magnetic field are obtained. It\nis shown that the effective polariton mass $M_{\\rm eff}$ increases with\nmagnetic field as $B^{1/2}$. The BEC critical temperature $T_{c}^{(0)}$\ndecreases as $B^{-1/4}$ and increases with the spring constant of the parabolic\ntrap. The Rabi splitting related to the creation of a magnetoexciton in a high\nmagnetic field in graphene and QW is obtained. It is shown that Rabi splitting\nin graphene can be controlled by the external magnetic field since it is\nproportional to $B^{-1/4}$, while in a QW the Rabi splitting does not depend on\nthe magnetic field when it is strong.",
        "positive": "Experimental measurement of the divergent quantum metric of an\n  exceptional point: The geometry of Hamiltonian's eigenstates is encoded in the quantum geometric\ntensor (QGT). It contains both the Berry curvature, central to the description\nof topological matter and the quantum metric. So far the full QGT has been\nmeasured only in Hermitian systems, where the role of the quantum metric is\nmostly shown to determine corrections to physical effects. On the contrary, in\nnon-Hermitian systems, and in particular near exceptional points, the quantum\nmetric is expected to diverge and to often play a dominant role, for example on\nthe enhanced sensing and on wave packet dynamics. In this work, we report the\nfirst experimental measurement of the quantum metric in a non-Hermitian system.\nThe specific platform under study is an organic microcavity with\nexciton-polariton eigenstates, which demonstrate exceptional points. We measure\nthe quantum metric's divergence and we determine the scaling exponent\n$n=-1.01\\pm0.08$, which is in agreement with theoretical predictions for the\nsecond-order exceptional points."
    },
    {
        "anchor": "Floquet-Bloch theory and topology in periodically driven lattices: We propose a general framework to solve tight binding models in D dimensional\nlattices driven by ac electric fields. Our method is valid for arbitrary\ndriving regimes and allows to obtain effective Hamiltonians for different\nexternal fields configurations. We establish an equivalence with time\nindependent lattices in D+1 dimensions, and analyze their topological\nproperties. Further, we demonstrate that non-adiabaticity drives a transition\nfrom topological invariants defined in D+1 to D dimensions. Our approach\nprovides a theoretical framework to analyze ac driven systems, with potential\napplications in topological states of matter, and non-adiabatic topological\nquantum computation, predicting novel outcomes for future experiments.",
        "positive": "Field-Emission Resonances in Thin Metallic Films: Nonexponential Decay\n  of the Tunneling Current as a Function of the Sample-to-Tip Distance: Field-emission resonances (FERs) for two-dimensional Pb(111) islands grown on\n\\mbox{Si(111)7$\\times$7} surfaces were studied by low-temperature scanning\ntunneling microscopy and spectroscopy (STM/STS) in a broad range of tunneling\nconditions with both active and disabled feedback loop. These FERs exist at\nquantized sample-to-tip distances $Z^{\\,}_n$ above the sample surface, where\n$n$ is the serial number of the FER state. By recording the trajectory of the\nSTM tip during ramping of the bias voltage $U$ (while keeping the tunneling\ncurrent $I$ fixed), we obtain the set of the $Z^{\\,}_n$ values corresponding to\nlocal maxima in the derived $dZ/dU(U)$ spectra. This way, the continuous\nevolution of $Z^{\\,}_n$ as a function of $U$ for all FERs was investigated by\nSTS experiments with active feedback loop for different $I$. Complementing\nthese measurements by current-distance spectroscopy at a fixed $U$, we could\nconstruct a 4-dimensional $I-U-Z-dZ/dU$ diagram, that allows us to investigate\nthe geometric localization of the FERs above the surface. We demonstrate that\n(i) the difference $\\delta Z^{\\,}_n=Z^{\\,}_{n+1}-Z^{\\,}_n$ between neighboring\nFER lines in the $Z-U$ diagram is independent of $n$ for higher resonances,\n(ii) the $\\delta Z^{\\,}_{n}$ value decreases as $U$ increases; (iii) the\nquantized FER states lead to the \\emph{periodic} variations of $\\ln I$ as a\nfunction of $Z$ with periodicity $\\delta Z$; (iv) the periodic variations in\nthe $\\ln I - Z$ spectra allows to estimate the absolute height of the tip above\nthe sample surface. Our findings contribute to a deeper understanding on how\nthe FER states affect various types of tunneling spectroscopy experiments and\nhow they lead to a non-exponential decay of the tunneling current as a function\nof $Z$ at high bias voltages in the regime of quantized electron emission."
    },
    {
        "anchor": "Exclusion of quantum coherence as the origin of the 2D metallic state in\n  high-mobility silicon inversion layers: The temperature and density dependence of the phase coherence time\n$\\tau_\\phi$ in high-mobility silicon inversion layers was determined from the\nmagnetoresistivity due to weak localization. The upper temperature limit for\nsingle-electron quantum interference effects was delineated by comparing\n$\\tau_\\phi$ with the momentum relaxation time $\\tau$. A comparison between the\ndensity dependence of the borders for quantum interference effects and the\nstrong resistivity drop reveals that theses effects are not related to each\nother. As the strong resistivity drop occurs in the Drude regime, the apparent\nmetallic behavior can not be caused by quantum coherent effects.",
        "positive": "Long-lived elementary excitations and light coherence in topological\n  lasers: Combining topologically-protected chiral light transport and laser\namplification gives rise to topological lasers, whose operation is immune to\nfabrication imperfections and defects, uncovering the role of topology in a\nnovel nonlinear non-Hermitian regime. We study a topological laser based on the\nphotonic Haldane model with selective pumping of chiral edge modes described by\nsaturable gain. We investigate elementary excitations around the mean-field\nsteady state and their consequences for the coherence properties. In\nparticular, we show that the hybridization of chiral edge modes gives rise to\nlong-lived elementary excitations, leading to large phase fluctuations in the\nemitted light field and a decrease of light coherence. In contrast to\ntopologically trivial lasers, the lifetime of elementary excitations is robust\nagainst disorder in topological lasers. However, the lifetime strongly depends\non the edge-mode dispersion around the lasing frequency. As a result, the\nlifetime can be reduced by orders of magnitude for lasing of different edge\nmodes, leading to a suppression of phase fluctuations and larger coherence of\nthe emitted light. On the other hand, amplitude fluctuations and the\nsecond-order autocorrelation function are moderately increased at the same\ntime."
    },
    {
        "anchor": "Spectral analysis of topological defects in an artificial spin-ice\n  lattice: Arrays of suitably patterned and arranged magnetic elements may display\nartificial spin-ice structures with topological defects in the magnetization,\nsuch as Dirac monopoles and Dirac strings. It is known that these defects\nstrongly influence the quasi-static and equilibrium behavior of the spin-ice\nlattice. Here we study the eigenmode dynamics of such defects in a square\nlattice consisting of stadium-like thin film elements using micromagnetic\nsimulations. We find that the topological defects display distinct signatures\nin the mode spectrum, providing a means to qualitatively and quantitatively\nanalyze monopoles and strings which can be measured experimentally.",
        "positive": "Quantum spin chains and Majorana states in arrays of coupled qubits: Several designs of inter-qubit coupling are considered. It is shown that by a\ncombination of Josephson and capacitive coupling one can realize qubit\ninteractions of variable spin content. Qubit arrays are discussed as models of\nquantum spin chains. In particular, a qubit model of the 1D quantum Ising spin\nchain is proposed. A realization of unpaired Majorana fermion states in this\nsystem is considered. It is shown that Majorana states are represented by spin\nflip excitations localized on the chain ends. Using unpaired Majorana states in\nqubit chains for decoherence protected quantum computing is discussed."
    },
    {
        "anchor": "Parity oscillations of Kondo temperature in a single molecule break\n  junction: We study the Kondo temperature ($T_K$) of a single molecule break junction.\nBy employing a numerical renormalization group calculations we have found that\n$T_K$ depends dramatically upon the position of the molecule in the wire formed\nbetween the contacts. We show that $T_K$ exhibits strong \\emph{oscillations}\nwhen the parity of the left {and/or} right number of atomic sites ($N_L,N_R$)\nis changed. For a given set of parameters, the maximum value of $T_K$ occurs\nfor ($odd,odd$) combination, while its minimum values is observed for\n($even,even$).\n  These oscillations are fully understood in terms of the effective\nhybridization function.",
        "positive": "Diffuson-driven Ultralow Thermal Conductivity in Amorphous Nb2O5 Thin\n  Films: Niobium pentoxide (Nb2O5) has been extensively reported for applications of\nelectrochemical energy storage, memristors, solar cells, light emitting diodes\n(LEDs), and electrochromic devices. The thermal properties of Nb2O5 play a\ncritical role in device performance of these applications. However, very few\nstudies on the thermal properties of Nb2O5 have been reported and a fundamental\nunderstanding of heat transport in Nb2O5 is still lacking. The present work\ncloses this gap and provides the first study of thermal conductivity of\namorphous Nb2O5 thin films. Ultralow thermal conductivity is observed without\nany size effect in films as thin as 48 nm, which indicates that propagons\ncontribute negligibly to the thermal conductivity and that the thermal\ntransport is dominated by diffusons. Density-function-theory (DFT) simulations\ncombined with a diffuson-mediated minimum-thermal-conductivity model confirms\nthis finding. Additionally, the measured thermal conductivity is lower than the\namorphous limit (Cahill model), which proves that the diffuson model works\nbetter than the Cahill model to describe the thermal conduction mechanism in\nthe amorphous Nb2O5 thin films. Additionally, the thermal conductivity does not\nchange significantly with oxygen vacancy concentration. This stable and low\nthermal conductivity facilitates excellent performance for applications such as\nmemristors."
    },
    {
        "anchor": "Commensurability oscillations in the SAW induced acousto-electric effect\n  in a 2DEG: We study the acousto-electric (AE) effect generated by surface acoustic waves\n(SAW) in a high mobility 2D electron gas (2DEG) with isotropic and especially\nsmall-angle impurity scattering. In both cases the acousto-electric effect\nexhibits Weiss oscillations periodic in $B^{-1}$ due to the commensurability of\nthe SAW period with the size of the cyclotron orbit and resonances at the SAW\nfrequency $\\omega=k\\omega_{c}$ multiple of the cyclotron frequency. We describe\nhow oscillations in the acousto-electric effect are damped in low fields where\n$\\omega_{c}\\tau_{\\ast}\\lesssim1$ (with the time scale $\\tau_{\\ast}$ dependent\non the type of scattering) and find its non-oscillatory part which remains\nfinite to the lowest fields.",
        "positive": "Strain-induced modulation of magnetic interactions in graphene: The ease with which the physical properties of graphene can be tuned suggests\na wide range of possible applications. Recently, strain engineering of these\nproperties has been of particular interest. Possible spintronic applications of\nmagnetically doped graphene systems have motivated recent theoretical\ninvestigations of the so-called Ruderman-Kittel-Kasuya-Yosida (RKKY)\ninteraction between localized moments in graphene. In this work a combination\nof analytic and numerical techniques are used to examine the effects of\nuniaxial strain on such an interaction. A range of interesting features are\nuncovered depending on the separation and strain directions. Amplification,\nsuppression, and oscillatory behavior are reported as a function of the strain\nand mathematically transparent expressions predicting these features are\nderived. Since a wide range of effects, including overall moment formation and\nmagnetotransport response, are underpinned by such interactions we predict that\nthe ability to manipulate the coupling by applying strain may lead to\ninteresting spintronic applications."
    },
    {
        "anchor": "Resonant and off-resonant microwave signal manipulation in coupled\n  superconducting resonators: We present an experimental demonstration as well as a theoretical model of an\nintegrated circuit designed for the manipulation of a microwave field down to\nthe single-photon level. The device is made of a superconducting resonator\ncoupled to a transmission line via a second frequency-tunable resonator. The\ntunable resonator can be used as a tunable coupler between the fixed resonator\nand the transmission line. Moreover, the manipulation of the microwave field\nbetween the two resonators is possible. In particular, we demonstrate the\nswapping of the field from one resonator to the other by pulsing the frequency\ndetuning between the two resonators. The behavior of the system, which\ndetermines how the device can be operated, is analyzed as a function of one key\nparameter of the system, the damping ratio of the coupled resonators. We show a\ngood agreement between experiments and simulations, realized by solving a set\nof coupled differential equations.",
        "positive": "Fractional Quantum Hall Effect and M-Theory: We propose a unifying model for FQHE which on the one hand connects it to\nrecent developments in string theory and on the other hand leads to new\npredictions for the principal series of experimentally observed FQH systems\nwith filling fraction $\\nu ={n\\over 2n\\pm1}$ as well as those with $\\nu\n={m\\over m+2}$. Our model relates these series to minimal unitary models of the\nVirasoro and superVirasoro algebra and is based on $SL(2, {\\bf C})$\nChern-Simons theory in Euclidean space or $SL(2,{\\bf R})\\times SL(2,{\\bf R})$\nChern-Simons theory in Minkowski space. This theory, which has also been\nproposed as a soluble model for 2+1 dimensional quantum gravity, and its N=1\nsupersymmetric cousin, provide effective descriptions of FQHE. The principal\nseries corresponds to quantized levels for the two $SL(2,{\\bf R})$'s such that\nthe diagonal $SL(2,{\\bf R})$ has level $ 1$. The model predicts, contrary to\nstandard lore, that for principal series of FQH systems the quasiholes possess\nnon-abelian statistics. For the multi-layer case we propose that complex ADE\nChern-Simons theories provide effective descriptions, where the rank of the ADE\nis mapped to the number of layers. Six dimensional $(2,0)$ ADE theories on the\nRiemann surface $\\Sigma$ provides a realization of FQH systems in M-theory.\nMoreover we propose that the q-deformed version of Chern-Simons theories are\nrelated to the anisotropic limit of FQH systems which splits the zeroes of the\nLaughlin wave function. Extensions of the model to 3+1 dimensions, which\nrealize topological insulators with non-abelian topologically twisted\nYang-Mills theory is pointed out."
    },
    {
        "anchor": "Dirac quantum kinetic equation: minimal conductivity revisited: The kinetic equation used for the description of Dirac systems does not fully\ntake into account two features that play an important role in the vicinity of\nthe Dirac point: (i) the spin degree of freedom, in particular if the spin-flip\nenergy $2 vp$ is not large anymore; and (ii) the failure of the semiclassical\napproximation due to the large Fermi wavelength. In our work, we propose a\nnovel quantum kinetic equation, which does not have these two drawbacks.\nExploiting it in the presence of short range disorder, we demonstrate how it\npredicts the correct minimal conductivity in 2D Dirac system, a result that has\nso far been obtained only by other methods like the Kubo formula. The nature of\nthe presented kinetic equation opens up the possibility for the kinetic\ndescription of deeply quantum and even strongly correlated Dirac systems.",
        "positive": "Near-field radiative heat transfer and van der Waals friction between\n  closely spaced graphene and amorphous SiO$_2$: We study the radiative heat transfer and the van der Waals friction between\ngraphene and an amorphous SiO$_2$ substrate. We study the surface\nphonon-polaritons contribution to the low-field mobility as a function of\ntemperature and of carrier density. We find that the electric current saturate\nat a high electric field, in agreement with experiment. The saturation current\ndepends weakly on the temperature, which we attribute to the \"quantum\" friction\nbetween the graphene carriers and the substrate optical phonons. We calculate\nthe frictional drag between two graphene sheets caused by van der Waals\nfriction, and find that this drag can induce a high enough voltage which can be\neasily measured experimentally. We find that for nonsuspended graphene the\nnear-field radiative heat transfer, and the heat transfer due to direct\nphononic coupling, are of the same order of magnitude at low electric field.\nThe phononic contribution to the heat transfer dominates at high field. For\nlarge separation between graphene and the substrate the heat transfer is\ndominated by the near-field radiative heat transfer."
    },
    {
        "anchor": "Majorana bound state induced drag current in capacitively coupled\n  quantum dots: We show that nonzero drag current in a double quantum-dot system, consisting\nof a biased drive dot and an unbiased passive dot coupled capacitively, can be\ngenerated by a Majorana bound state located at one of the leads connected to\nthe passive dot. Importantly, the drag current induced by Majorana bound\nstates, either an isolated Majorana bound state or two weakly coupled but\nspatially separated Majorana modes, shows qualitative differences from that\ninduced by a near-zero-energy Andereev bound state. Thus, other than the\ntunneling spectroscopy, the proposed setup can serve as a complementary tool to\ndetect Majorana fermions in proximitized Rashba nanowires.",
        "positive": "Realization of a vertical topological p-n junction in epitaxial\n  $\\mathrm{Sb_2Te_3 / Bi_2Te_3}$ heterostructures: 3D topological insulators are a new state of quantum matter which exhibits\nboth a bulk band structure with an insulating energy gap as well as metallic\nspin-polarized Dirac fermion states when interfaced with a topologically\ntrivial material. There have been various attempts to tune the Dirac point to a\ndesired energetic position for exploring its unusual quantum properties. Here\nwe show a direct experimental proof by angle-resolved photoemission of the\nrealization of a vertical topological p-n junction made of a heterostructure of\ntwo different binary 3D TI materials $\\mathrm{Bi_2Te_3}$ and\n$\\mathrm{Sb_2Te_3}$ epitaxially grown on Si(111). We demonstrate that the\nchemical potential is tunable by about 200 meV when decreasing the upper\n$\\mathrm{Sb_2Te_3}$ layer thickness from 25 to 6 quintuple layers without\napplying any external bias. These results make it realistic to observe the\ntopological exciton condensate and pave the way of exploring other exotic\nquantum phenomena in the near future."
    },
    {
        "anchor": "Thermoelectric effect in high mobility single layer epitaxial graphene: The thermoelectric response of high mobility single layer epitaxial graphene\non silicon carbide substrates as a function of temperature and magnetic field\nhave been investigated. For the temperature dependence of the thermopower, a\nstrong deviation from the Mott relation has been observed even when the carrier\ndensity is high, which reflects the importance of the screening effect. In the\nquantum Hall regime, the amplitude of the thermopower peaks is lower than a\nquantum value predicted by theories, despite the high mobility of the sample. A\nsystematic reduction of the amplitude with decreasing temperature suggests that\nthe suppression of the thermopower is intrinsic to Dirac electrons in graphene.",
        "positive": "Photoluminescence and charge transfer in the prototypical 2D/3D\n  semiconductor heterostructure MoS$_2$/GaAs: The new generation of two-dimensional (2D) materials has shown a broad range\nof applications for optical and electronic devices. Understanding the\nproperties of these materials when integrated with the more traditional\nthree-dimensional (3D) semiconductors is an important challenge for the\nimplementation of ultra-thin electronic devices. Recent observations have shown\nthat by combining MoS$_2$ with GaAs it is possible to develop high quality\nphotodetectors and solar cells. Here, we present a study of the effects of\nintrinsic GaAs, p-doped GaAs, and n-doped GaAs substrates on the\nphotoluminescence of monolayer MoS$_2$. We observe a decrease of an order of\nmagnitude in the emission intensity of MoS$_2$ in all MoS$_2$/GaAs\nheterojunctions, when compared to a control sample consisting of a MoS$_2$\nmonolayer isolated from GaAs by a few layers of hexagonal boron nitride. We\nalso see a dependence of the trion to A-exciton emission ratio in the\nphotoluminescence spectra on the type of substrate, a dependence that we relate\nto the static charge exchange between MoS$_2$ and the substrates when the\njunction is formed. Scanning Kelvin probe microscopy measurements of the\nheterojunctions suggest type-I band alignments, so that excitons generated on\nthe MoS$_2$ monolayer will be transferred to the GaAs substrate. Our results\nshed light on the charge exchange leading to band offsets in 2D/3D\nheterojunctions which play a central role in the understanding and further\nimprovement of electronic devices."
    },
    {
        "anchor": "Quantum dynamics of vortices in mesoscopic magnetic disks: Model of quantum depinning of magnetic vortex cores from line defects in a\ndisk geometry and under the application of an in-plane magnetic field has been\ndeveloped within the framework of the Caldeira-Leggett theory. The\ncorresponding instanton solutions are computed for several values of the\nmagnetic field. Expressions for the crossover temperature Tc and for the\ndepinning rate \\Gamma(T) are obtained. Fitting of the theory parameters to\nexperimental data is also presented.",
        "positive": "Exceptional points for chiral Majorana fermions in arbitrary dimensions: Certain real parameters of a Hamiltonian, when continued to complex values,\ncan give rise to singular points called exceptional points ($EP$'s), where two\nor more eigenvalues coincide and the complexified Hamiltonian becomes\nnon-diagonalizable. We show that for a generic $d$-dimensional topological\nsuperconductor / superfluid with a chiral symmetry, one can find $EP$'s\nassociated with the chiral zero energy Majorana fermions bound to a topological\ndefect / edge. Exploiting the chiral symmetry, we propose a formula for\ncounting the number ($n$) of such chiral zero modes. We also establish the\nconnection of these solutions to the Majorana fermion wavefunctions in the\nposition space. The imaginary parts of these momenta are related to the\nexponential decay of the wavefunctions localized at the defect / edge, and\nhence their changes of signs at a topological phase transition point signal the\nappearance or disappearance of chiral Majorana zero modes. Our analysis thus\nexplains why topological invariants like the winding number, defined for the\ncorresponding Hamiltonian in the momentum space for a defectless system with\nperiodic boundary conditions, capture the number of admissible Majorana fermion\nsolutions for the position space Hamiltonian with defect(s). Finally, we\nconclude that $EP$'s cannot be associated with the Majorana fermion\nwavefunctions for systems with no chiral symmetry, although one can use our\nformula for counting $n$, using complex $k$ solutions where the determinant of\nthe corresponding BdG Hamiltonian vanishes."
    },
    {
        "anchor": "Energy correlations for a random matrix model of disordered bosons: Linearizing the Heisenberg equations of motion around the ground state of an\ninteracting quantum many-body system, one gets a time-evolution generator in\nthe positive cone of a real symplectic Lie algebra. The presence of disorder in\nthe physical system determines a probability measure with support on this cone.\nThe present paper analyzes a discrete family of such measures of exponential\ntype, and does so in an attempt to capture, by a simple random matrix model,\nsome generic statistical features of the characteristic frequencies of\ndisordered bosonic quasi-particle systems. The level correlation functions of\nthe said measures are shown to be those of a determinantal process, and the\nkernel of the process is expressed as a sum of bi-orthogonal polynomials. While\nthe correlations in the bulk scaling limit are in accord with sine-kernel or\nGUE universality, at the low-frequency end of the spectrum an unusual type of\nscaling behavior is found.",
        "positive": "Surface Green's functions and quasiparticle interference in Weyl\n  semimetals: We use the exact analytical technique introduced in Phys. Rev. B 101, 115405\nto recover the surface Green's functions and the corresponding Fermi-arc\nsurface states for various lattice models of Weyl semimetals. For these models\nwe use the T-matrix formalism to calculate the quasiparticle interference\npatterns generated in the presence of impurity scattering. In particular, we\nconsider the models introduced in Phys. Rev. B 93, 041109(R) (A) and Phys. Rev.\nLett. 119, 076801 (B), and we find that, as opposed to observations previously\nobtained via joint density of states and spin-dependent scattering probability,\nthe inter-arc scattering in the quasiparticle interference features is fully\nsuppressed in model A, and very small in model B. Our findings indicate that\nthese models may not correctly describe materials such as MoTe2, since for such\nmaterials inter-arc scattering is clearly visible experimentally, e.g., in\nNature Phys. 12, 1105-1110 (2016). We also focus on the minimal models proposed\nby McCormick et al. in Phys. Rev. B 95, 075133, which indeed recover\nsignificant inter-arc scattering features."
    },
    {
        "anchor": "Quantum statistics of polariton parametric interactions: Using a high-quality GaAs planar microcavity, we optically generate polariton\npairs, and verify their correlations by means of time-resolved single-photon\ndetection. We find that correlations between the different modes are\nconsistently lower than identical mode correlations, which is attributed to the\npresence of uncorrelated background. We discuss a model to quantify the effects\nof such a background on the observed correlations. Using spectral and temporal\nfiltering, the background can be suppressed and a change in photon statistics\ntowards non-classical correlations is observed. These results improve our\nunderstanding of the statistics of polariton-polariton scattering and\nbackground mechanisms, and pave the way to the generation of entangled\npolariton pairs.",
        "positive": "Tunable effective g-factor in InAs nanowire quantum dots: We report tunneling spectroscopy measurements of the Zeeman spin splitting in\nInAs few-electron quantum dots. The dots are formed between two InP barriers in\nInAs nanowires with a wurtzite crystal structure grown by chemical beam\nepitaxy. The values of the electron g-factors of the first few electrons\nentering the dot are found to strongly depend on dot size and range from close\nto the InAs bulk value in large dots |g^*|=13 down to |g^*|=2.3 for the\nsmallest dots. These findings are discussed in view of a simple model."
    },
    {
        "anchor": "Electronic states of laterally coupled quantum rings: The conduction band electron states of laterally-coupled semiconductor\nquantum rings are studied within the frame of the effective mass envelope\nfunction theory. We consider the effect of axial and in-plane magnetic fields\nfor several inter-ring distances, and find strong changes in the energy\nspectrum depending on the coupling regime. Our results indicate that the\nmagnetic response accurately monitors the quantum ring molecule dissociation\nprocess. Moreover, the anisotropic response of the electron states to in-plane\nmagnetic fields provides information on the orientation of the quantum ring\nmolecule.",
        "positive": "Addition Spectrum Oscillations of Fractional Quantum Hall Dots: Quantum dots in the fractional quantum Hall regime are studied using a\nHartree formulation of composite fermion theory. Under appropriate conditions\nthe chemical potential of the dots will oscillate periodically with B due to\nthe transfer of composite fermions between quasi-Landau bands. This effect is\nanalogous to the addition spectrum oscillations which occur in quantum dots in\nthe integer quantum Hall regime. Period phi_0 oscillations are found in sharply\nconfined dots with filling factors nu=2/5 and nu=2/3. Period 3*phi_0\noscillations are found in a parabolically confined nu=2/5 dot. More generally,\nwe argue that the oscillation period of dots with band pinning should vary\ncontinuously with B whereas the period of dots without band pinning is phi_0.\nFinally, we discuss the possibility of detecting fractionally charged\nexcitations using the observed period of addition spectrum oscillations."
    },
    {
        "anchor": "Density-induced reorientation of the stripe at half-filled high Landau\n  levels: The effect of a unidirectional periodic potential on the orientation of the\nstripe state is studied for the two-dimensional electron system at half-filled\nhigh Landau levels. By considering a quantum well with two electric subbands,\nit is found that the stripe is parallel to the external potential for weak\nmodulation and is orthogonal for strong modulation. In the intermediate range,\nthe orientation of the stripe changes from orthogonal to parallel as the\nelectron density is increased. This result explains the recent experiment\nperformed by J. Zhu {\\it et al} that the anisotropy axis at half-filled high\nLandau levels rotates by $90^0$ by increasing the electron density. It also\nsupports the suggestion that the stripes is pinned by the native surface\nmorphology at the interface of the heterojunction.",
        "positive": "Continuum of Metastable Helical States in Monoaxial Chiral Magnets:\n  Effect of the Boundary Conditions: In a recent publication we showed that a monoaxial chiral magnet has a\ncontinuum of metastable helical states differing by the helix wave number. This\nintringuing result was obtained for the case of an infinite magnet (or of a\nmagnet with periodic boundary conditions). However, it has been pointed out\nthat in a real magnet only one of these states is compatible with the boundary\nconditions, because the helix wave number is determined by the surface chiral\ntwist. Thus, only one of the continuum of states is physically realizable. This\nis true for the case of a chiral magnet in contact with a non magnetic medium\n(vacuum or air, for instance), but the boundary conditions can be altered by\nsetting the chiral magnet in contact with another magnetic medium, which may be\nable to absorb the surface chiral twist. We show here that this is indeed the\ncase by studying a composite magnet system, which consists of one monoaxial\nchiral magnet of rectangular parallelepiped shape which has two similar\nuniaxial ferromagnets attached to each of the faces that are perpendicular to\nthe chiral axis. We show that, in the case of zero applied field, this\ncomposite system has a number of metastable helical states which is\nproportional to the length L0 of the chiral magnet along the chiral axis, and\nthat the results of our previous publication are recovered when L0 tends to\ninfinity."
    },
    {
        "anchor": "Conductance of a molecular junction mediated by unconventional\n  metal-induced gap states: The conductance of a molecular junction is commonly determined by either\ncharge-transfer-doping, where alignment of the Fermi energy to the molecular\nlevels is achieved, or tunnelling through the tails of molecular resonances\nwithin the highest-occupied and lowest-unoccupied molecular-orbital gap.\n  Here, we present an alternative mechanism where electron transport is\ndominated by electrode surface states. They give rise to metallization of the\nmolecular bridge and additional, pronounced conductance resonances allowing for\nsubstantial tailoring of its electronic properties via, e.g. a gate voltage.\nThis is demonstrated in a field-effect geometry of a fullerene-bridge between\ntwo metallic carbon nanotubes.",
        "positive": "Spin structure of Graphene/Pt interface for spin current formation and\n  induced magnetization in deposited (Ni-Fe)-nanodots: Spin electronic structure of graphene pi-states and Pt 5d-states for the\nGraphene/Pt interface has been investigated. Here, we report a large induced\nspin-orbit splitting (~70-100 meV) of graphene pi-states with formation of\nnon-degenerated Dirac-cone spin states at the K-point of the BZ crossed with\nspin-polarized Pt 5d-states at Fermi level that opens up a possibility for\ncreation of new spintronics devices. We propose to use this spin structure for\nformation of spin current with spin locked perpendicular to the momentum for\ninduced remagnetization of the (Ni-Fe)-nanodots arranged atop the interface.\nTheoretical estimations of the spin current created at the Graphene/Pt\ninterface and the induced intrinsic effective magnetic field leading to the\nin-plane remagnetization of the NiFe-nanodots due to spin-orbit torque effect\nare presented. By micromagnetic modeling based on experimentally observed\nspin-orbit splitting we demonstarte that the induced intrinsic magnetic field\nmight be effectively used for magnetization swithching of the deposited\n(Ni-Fe)-nanodots."
    },
    {
        "anchor": "Verification of \u0393$_{7}$ symmetry assignment for the top valence\n  band of ZnO by magneto-optical studies of the free A exciton state: The circularly-polarized and angular-resolved magneto-photoluminescence\nspectroscopy was carried out to study the free A exciton 1S state in wurtzite\nZnO at 5 K.",
        "positive": "Four-band effective square lattice model for Bernal-stacked bilayer\n  graphene: Bernal-stacked bilayer graphene (BLG) provides an ideal basis for\ngate-controlled, and free of etching, electronic devices. Theoretical modeling\nof realistic devices is an essential part of research, however, simulations of\nlarge-scale BLG devices continue to be extremely challenging. Micrometer-sized\nsystems are predominantly beyond the reach of the commonly used atomistic\ntight-binding method, while other numerical approaches based on the two\ndimensional Dirac equation are not straightforward to conduct due to the\nfermion doubling problem. Here we present an approach based on the continuum\nmodel, unharmed by the fermion doubling. The discretization of the BLG\ncontinuum Hamiltonian leads to an effective four-band model, with both valleys\nbuilt-in. We demonstrate its performance with realistic, large-scale systems,\nand obtain results consistent with experiments and with the tight-binding\nmodel, over a broad range of magnetic field."
    },
    {
        "anchor": "Aharonov-Bohm and Aharonov-Casher effects in double quantum dot\n  Josephson junction: We analyze a Josephson junction between two superconductors interconnected\nthrough a normal-state nanostructure made of two parallel nanowires with\nembedded quantum dots. We study the influence of interference effects due to\nthe Aharonov-Bohm (AB) and Aharonov-Casher (AC) phases for local and nonlocal\n(split) Cooper pairs. In the AB effect the phase of electron is affected by\nmagnetic flux, while in the AC effect the phase of the electron in solid state\ncan be modified due to the Rashba spin-orbit coupling. In the low-transmission\nregime the AB and AC effects can be related to only local or nonlocal Cooper\npair transport, respectively. We demonstrate that by the addition of the\nquantum dots the Cooper pair splitting can be made perfectly efficient, and\nthat the AC phase is different for non-spin-flip and spin-flip transport\nprocesses.",
        "positive": "Andreev reflection from non-centrosymmetric superconductors and Majorana\n  bound state generation in half-metallic ferromagnets: We study Andreev reflection at an interface between a half metal and a\nsuperconductor with spin-orbit interaction. While the absence of minority\ncarriers in the half metal makes singlet Andreev reflection impossible, the\nspin-orbit interaction gives rise to triplet Andreev reflection, i.e., the\nreflection of a majority electron into a majority hole or vice versa. As an\napplication of our calculation, we consider a thin half metal film or wire\nlaterally attached to a superconducting contact. If the half metal is disorder\nfree, an excitation gap is opened that is proportional to the spin-orbit\ninteraction strength in the superconductor. For electrons with energy below\nthis gap a lateral half-metal--superconductor contact becomes a perfect triplet\nAndreev reflector. We show that the system supports localized Majorana end\nstates in this limit."
    },
    {
        "anchor": "Electron spin diffusion in monolayer MoS$_2$: Electron spin diffusion is investigated in monolayer MoS$_2$ in the absence\nof external electric and magnetic fields. The electron-impurity scattering,\nwhich is shown to play a negligible role in spin relaxation in time domain in\nthis material, has a marked effect on the in-plane spin diffusion due to the\nanisotropic spin precession frequency in the spatial domain. With the\nelectron-impurity and inter-valley electron-phonon scatterings separately\nincluded in the scattering term, we study the intra- and inter-valley diffusion\nprocesses of the in-plane spins by analytically solving the kinetic spin Bloch\nequations. The intra-valley process is found to be dominant in the in-plane\nspin diffusion, in contrast to the case of spin relaxation in time domain,\nwhere the inter-valley process can be comparable to or even more important than\nthe intra-valley one. For the intra-valley process, we find that the in-plane\nspin diffusion is suppressed with the increase of impurity density but\neffectively enhanced by increasing electron density in both the degenerate and\nnondegenerate limits. We also take into account the electron-electron Coulomb\nscattering in the intra-valley process. Interestingly, we find that in the\nnondegenerate limit, the intra-valley spin diffusion length presents an\nopposite trend in the electron density dependence compared to the one with only\nelectron-impurity scattering.",
        "positive": "Gate-defined Josephson weak-links in monolayer $\\mathrm{WTe_2}$: Systems combining superconductors with topological insulators offer a\nplatform for the study of Majorana bound states and a possible route to realize\nfault tolerant topological quantum computation. Among the systems being\nconsidered in this field, monolayers of tungsten ditelluride ($\\mathrm{WTe_2}$)\nhave a rare combination of properties. Notably, it has been demonstrated to be\na Quantum Spin Hall Insulator (QSHI) and can easily be gated into a\nsuperconducting state. We report measurements on gate-defined Josephson\nweak-link devices fabricated using monolayer $\\mathrm{WTe_2}$. It is found that\nconsideration of the two dimensional superconducting leads are critical in the\ninterpretation of magnetic interference in the resulting junctions. The\nreported fabrication procedures suggest a facile way to produce further devices\nfrom this technically challenging material and the results mark the first step\ntoward realizing versatile all-in-one topological Josephson weak-links using\nmonolayer $\\mathrm{WTe_2}$."
    },
    {
        "anchor": "Dependence of Single Molecule Junction Conductance on Molecular\n  Conformation: The conductance of a single metal-molecule-metal junction depends critically\non the conformations of the molecule. In the simple case of a biphenyl, two\nphenyl rings linked together by a single C-C bond, the conductance is expected\nto depend on the relative twist angle between the two rings, with the planar\nconformation having the highest conductance. A number of different techniques\nhave measured the conductance of metal-molecule(s)-metal junctions. However,\nthe conductance variation from junction to junction has made it difficult to\nverify even the simplest predictions about how molecules should behave in\nunimolecular devices. Here, using amine link groups to form single molecule\njunctions, we show a clear correlation between molecule conformation and\njunction conductance in a series of seven biphenyl molecules with different\nring substitutions that alter the twist angle of the molecules. We find that\nthe conductance for the series decreases with increasing twist angle,\nconsistent with a cosine squared relation predicted theoretically for transport\nthrough pi-conjugated systems.",
        "positive": "Efficient X-ray generation from gold colloidal solutions: Hard X-ray generation for Au nanoparticle dispersion was systematically\ninvestigated for different particle diameters ranging from 10 to 100 nm with a\nnarrow size distribution of +/- 2%. Scaling law of X-ray generation is close to\na 6-photon process before the onset of saturation for excitation by 45 fs laser\npulses with central wavelength of 800 nm. This is consistent with bulk plasmon\nexcitation at wavelength ~ 138 nm. The longitudinal E-field component due to\nnanoparticle focusing is responsible for the excitation of the longitudinal\nbulk plasmon. The proposed analysis also explains X-ray emission from water\nbreakdown via an electron solvation mechanism at ~6.2 eV. The most efficient\nemission of X-rays was observed for 40 +/- 10 nm diameter nanoparticles which\nalso had the strongest UV extinction. X-ray emission was the most efficient\nwhen induced by pre-chirped 370 +/- 20 fs laser pulses and exhibited the\nhighest intensity at a negative chirp."
    },
    {
        "anchor": "Nonlocal electrical detection of spin accumulation generated by\n  Anomalous Hall effects in mesoscopic Ni_81Fe_19 films: Spin accumulation generated by the anomalous Hall effects (AHE) in mesoscopic\nferromagnetic Ni81Fe19 (permalloy or Py) films is detected electrically by a\nnonlocal method. The reciprocal phenomenon, inverse spin Hall effects (ISHE),\ncan also be generated and detected all-electrically in the same structure. For\naccurate quantitative analysis, a series of nonlocal AHE/ISHE structures and\nsupplementary structures are fabricated on each sample substrate to account for\nstatistical variations and to accurately determine all essential physical\nparameters in-situ. By exploring Py thicknesses of 4 nm, 8 nm, and 12 nm, the\nPy spin diffusion length {\\lambda}_Py is found to be much shorter than the film\nthicknesses. The product of {\\lambda}_Py and the Py spin Hall angle {\\alpha}_SH\nis determined to be independent of thickness and resistivity:\n{\\alpha}_SH*{\\lambda}_Py= (0.066 +/- 0.009) nm at 5 K and (0.041 +/- 0.010) nm\nat 295 K. These values are comparable to those obtained from mesoscopic Pt\nfilms.",
        "positive": "Coherent Excitonic Quantum Beats in Time-Resolved Photoemission\n  Measurements: Coherent excitation of materials via ultrafast laser pulses can have\ninteresting, observable dynamics in time-resolved photoemission measurements.\nThe broad spectral width of ultrafast pump pulses can coherently excite\nmultiple exciton energy levels. When such coherently excited states are probed\nby means of photoemission spectroscopy, interference between the polarization\nof different exciton levels can lead to observable coherent exciton beats.\nHere, we present the theoretical formalism for evaluating the Time- and Angle-\nResolved Photoemission Spectra (tr-ARPES) arising from the coherently excited\nexciton states. We subsequently apply our formalism to a simple model example\nof hydrogenic exciton energy levels to identify the dependencies that control\nthe quantum beats. Our findings indicate that the most pronounced effect of\ncoherent quantum excitonic beats is seen midway between the excited exciton\nenergy levels and the central energy of the pump pulse provides tunability of\nthis effect."
    },
    {
        "anchor": "Face centered cubic SnSe as a $\\mathbb{Z}_2$ trivial Dirac nodal line\n  material: The presence of a Dirac nodal line in a time-reversal and inversion symmetric\nsystem is dictated by the $\\mathbb{Z}_2$ index when spin-orbit interaction is\nabsent. In a first principles calculation, we show that a Dirac nodal line can\nemerge in $\\mathbb{Z}_2$ trivial material by calculating the band structure of\nSnSe in a face centered cubic lattice as an example. We qualitatively show that\nit becomes a topological crystalline insulator when spin-orbit interaction is\ntaken into account. We clarify the origin of the Dirac nodal line by obtaining\nirreducible representations corresponding to bands and explain the triviality\nof the $\\mathbb{Z}_2$ index. We construct an effective model representing the\nDirac nodal line using the {\\bf k}$\\cdot${\\bf p} method, and discuss the Berry\nphase and a surface state expected from the Dirac nodal line.",
        "positive": "Quantum hydrodynamics and nonlinear differential equations for\n  degenerate Fermi gas: We present new nonlinear differential equations for spacetime correlation\nfunctions of Fermi gas in one spatial dimension. The correlation functions we\nconsider describe non-stationary processes out of equilibrium. The equations we\nobtain are integrable equations. They generalize known nonlinear differential\nequations for correlation functions at equilibrium and provide vital tools to\nstudy non-equilibrium dynamics of electronic systems. The method we developed\nis based only on Wick's theorem and the hydrodynamic description of the Fermi\ngas. Differential equations appear directly in bilinear form."
    },
    {
        "anchor": "Computational Study of Ultrathin CNT Films with the Scalable Mesoscopic\n  Distinct Element Method: In this work we present a computational study of the small strain mechanics\nof freestanding ultrathin CNT films under in-plane loading. The numerical\nmodeling of the mechanics of representatively large specimens with realistic\nmicro- and nanostructure is presented. Our simulations utilize the scalable\nimplementation of the mesoscopic distinct element method of the waLBerla\nmulti-physics framework. Within our modeling approach, CNTs are represented as\nchains of interacting rigid segments. Neighboring segments in the chain are\nconnected with elastic bonds, resolving tension, bending, shear and torsional\ndeformations. These bonds represent a covalent bonding within CNT surface and\nutilize Enhanced Vector Model (EVM) formalism. Segments of the neighboring CNTs\ninteract with realistic coarse-grained anisotropic vdW potential, enabling\nrelative slip of CNTs in contact. The advanced simulation technique allowed us\nto gain useful insights on the behavior of CNT materials. In particular, it was\nestablished that the energy dissipation during CNT sliding leads to extended\nload transfer that conditions material-like mechanical response of the weakly\nbonded assemblies of CNTs.",
        "positive": "Network model for periodically strained graphene: The long-wavelength physics of monolayer graphene in the presence of periodic\nstrain fields has a natural chiral scattering network description. When the\nstrain field varies slowly compared to the graphene lattice and the effective\nmagnetic length of the induced valley pseudomagnetic field, the low-energy\nphysics can be understood in terms of valley-polarized percolating domain-wall\nmodes. Inspired by a recent experiment, we consider a strain field with\nthreefold rotation and mirror symmetries but without twofold rotation symmetry,\nresulting in a system with the connectivity of the oriented kagome network.\nScattering processes in this network are captured by a symmetry-constrained\nphenomenological $S$ matrix. We analyze the phase diagram of the kagome\nnetwork, and show that the bulk physics of the strained graphene can be\nqualitatively captured by the network when we account for a percolation\ntransition at charge neutrality. We also discuss the limitations of this\napproach to properly account for boundary physics."
    },
    {
        "anchor": "Microwave-driven ferromagnet--topological-insulator heterostructures:\n  The prospect for giant spin battery effect and quantized charge pump devices: We study heterostructures where a two-dimensional topological insulator (TI)\nis attached to two normal metal (NM) electrodes while an island of a\nferromagnetic insulator (FI) with precessing magnetization covers a portion of\nits lateral edges to induce time-dependent exchange field underneath via the\nmagnetic proximity effect. When the FI island covers both lateral edges, such\ndevice pumps pure spin current in the absence of any bias voltage, thereby\nacting as an efficient spin battery with giant output current even at very\nsmall microwave power input driving the precession. When only one lateral edge\nis covered by the FI island, both charge and spin current are pumped into the\nNM electrodes. We delineate conditions for the corresponding conductances\n(current-to-microwave-frequency ratio) to be quantized in a wide interval of\nprecession cone angles, which is robust with respect to weak disorder and can\nbe further extended by changes in device geometry.",
        "positive": "Band Offset in (Ga,In)As/Ga(As,Sb) Heterostructures: A series of (Ga,In)As/GaAs/Ga(As,Sb) multi-quantum well heterostructures is\nanalyzed using temperature- and power-dependent photoluminescence (PL)\nspectroscopy. Pronounced PL variations with sample temperature are observed and\nanalyzed using microscopic many-body theory and band structure calculations\nbased on the k$\\cdot$p method. This theory-experiment comparison reveals an\nunusual, temperature dependent variation of the band alignment between the\n(Ga,In)As and Ga(As,Sb) quantum wells."
    },
    {
        "anchor": "Electron transport through a strongly correlated monoatomic chain: We study transport properties of a strongly correlated monoatomic chain\ncoupled to metallic leads. Our system is described by tight binding\nHubbard-like model in the limit of strong on-site electron-electron\ninteractions in the wire. The equation of motion technique in the slave boson\nrepresentation has been applied to obtain analytical and numerical results.\nCalculated linear conductance of the system shows oscillatory behavior as a\nfunction of the wire length. We have also found similar oscillations of the\nelectron charge in the system. Moreover our results show spontaneous spin\npolarization in the wire. Finally, we compare our results with those for\nnon-interacting chain and discuss their modifications due to the Coulomb\ninteractions in the system.",
        "positive": "Robust quantum coherence above the Fermi sea: In this paper we present an experiment where we measured the quantum\ncoherence of a quasiparticle injected at a well-defined energy above the Fermi\nsea into the edge states of the integer quantum Hall regime. Electrons are\nintroduced in an electronic Mach-Zehnder interferometer after passing through a\nquantum dot that plays the role of an energy filter. Measurements show that\nabove a threshold injection energy, the visibility of the quantum interferences\nis almost independent of the energy. This is true even for high energies, up to\n130~$\\mu$eV, well above the thermal energy of the measured sample. This result\nis in strong contradiction with our theoretical predictions, which instead\npredict a continuous decrease of the interference visibility with increasing\nenergy. This experiment raises serious questions concerning the understanding\nof excitations in the integer quantum Hall regime."
    },
    {
        "anchor": "Fabrication of damage-free and/or contamination-free sub-um electrodes\n  using PMMA masks: Quality of the electrical contacts and interfaces in various\nmetal/semiconductor/insulator heterostructures is one of the pivotal aspects in\nboth applied and fundamental research areas. For instance, non-optimal contact\nresistance can limit the overall efficiency of a certain developed technology\nand thus considerably narrow the range or fully block its practical\napplication. On the other hand in fundamental research it is often the case\nthat the manifestation of targeted phenomenon crucially depends on the level of\ncontamination in the fabricated experimental samples. Here we offer a set of\nrecipes that are aimed at contamination-free and damage-free fabrication of the\ndevices, mostly developed for the two dimensional materials, but nevertheless\napplicable for a wider range of the systems, where the quality of the\ninterfaces and/or non-invasiveness of the fabrication recipes are important.\nOur recipes are based on the preparation of the flexible PMMA membranes, with\nthe help of which we can prepare residue-free or damage-free electrical\nconnections to the studied material.",
        "positive": "Investigation of potassium-intercalated bulk MoS$_2$ using transmission\n  electron energy-loss spectroscopy: We have investigated the effect of potassium (K) intercalation on\n$2H$-MoS$_2$ using transmission electron energy-loss spectroscopy. For K\nconcentrations up to approximately 0.4, the crystals appear to be inhomogeneous\nwith a mix of structural phases and irregular potassium distribution. Above\nthis intercalation level, MoS$_2$ exhibits a $2a \\times 2a$ superstructure in\nthe $ab$ plane and unit cell parameters of a = 3.20 $\\unicode{x212B}$ and c =\n8.23 $\\unicode{x212B}$ indicating a conversion from the $2H$ to the $1T'$ or\n$1T''$ polytypes. The diffraction patterns also show a $\\sqrt{3}a \\times\n\\sqrt{3}a$ and a much weaker $2\\sqrt{3}a \\times 2\\sqrt{3}a$ superstructure that\nis very likely associated with the ordering of the potassium ions. A\nsemiconductor-to-metal transition occurs signified by the disappearance of the\nexcitonic features from the electron energy-loss spectra and the emergence of a\ncharge carrier plasmon with an unscreened plasmon frequency of 2.78 eV. The\nplasmon has a positive, quadratic dispersion and appears to be superimposed\nwith an excitation arising from interband transitions. The behavior of the\nplasmon peak energy positions as a function of potassium concentration shows\nthat potassium stoichiometries of less than $\\sim 0.3$ are thermodynamically\nunstable while higher stoichiometries up to $\\sim 0.5$ are thermodynamically\nstable. Potassium concentrations greater than $\\sim 0.5$ lead to the\ndecomposition of MoS$_2$ and the formation of K$_2$S. The real part of the\ndielectric function and the optical conductivity of K$_{0.41}$MoS$_2$ were\nderived from the loss spectra via Kramers-Kronig analysis."
    },
    {
        "anchor": "Unitarity of scattering and edge spin accumulation: We consider a 2D ballistic and quasi-ballistic structures with\nspin-orbit-related splitting of the electron spectrum. The ballistic region is\nattached to the leads with a voltage applied between them. We calculate the\nedge spin density which arises in the presence of a charge current through the\nstructure. We solve the problem with the use of the method of scattering states\nand clarify the important role of the unitarity of scattering. In the case of a\nstraight boundary it leads to exact cancellation of long-wavelength\noscillations of the spin density. In general, however, the smooth spin\noscillations with the spin precession length may arise, as it happens, e.g.,\nfor the wiggly boundary. Moreover, we show that the result crucially depends on\nthe form of the spin-orbit Hamiltonian.",
        "positive": "Super-Poissonian noise in a Coulomb blockade metallic quantum dot\n  structure: The shot noise of the current through a single electron transistor (SET),\ncoupled capacitively with an electronic box, is calculated, using the master\nequation approach. We show that the noise may be sub-Poissonian or strongly\nsuper-Poissonian, depending mainly on the box parameters and the gate. The\nstudy also supports the idea that not negative differential conductance, but\ncharge accumulation in the quantum dot, responds for the super-Poissonian noise\nobserved."
    },
    {
        "anchor": "Thermoelectric effect in molecular electronics: We provide a theoretical estimate of the thermoelectric current and voltage\nover a Phenyldithiol molecule. We also show that the thermoelectric voltage is\n(1) easy to analyze, (2) insensitive to the detailed coupling to the contacts,\n(3) large enough to be measured and (4) give valuable information, which is not\nreadily accessible through other experiments, on the location of the Fermi\nenergy relative to the molecular levels. The location of the Fermi-energy is\npoorly understood and controversial even though it is a central factor in\ndetermining the nature of conduction (n- or p-type). We also note that the\nthermoelectric voltage measured over Guanine molecules with an STM by Poler et\nal., indicate conduction through the HOMO level, i.e., p-type conduction.",
        "positive": "Quantum-information processing in semiconductor quantum dots: We propose an all-optical implementation of quantum-information processing in\nsemiconductor quantum dots, where electron-hole excitations (excitons) serve as\nthe computational degrees of freedom (qubits). The strong dot confinement leads\nto a strong renormalization of excitonic states, which, in analogy to NMR-based\nimplementations of quantum-information processing, can be exploited for\nperforming conditional and unconditional qubit operations."
    },
    {
        "anchor": "Relaxation of Radiation-Driven Two-Level Systems Interacting with a\n  Bose-Einstein Condensate Bath: We develop a microscopic theory for the relaxation dynamics of an optically\npumped two-level system (TLS) coupled to a bath of weakly interacting Bose gas.\nUsing Keldysh formalism and diagrammatic perturbation theory, expressions for\nthe relaxation times of the TLS Rabi oscillations are derived when the boson\nbath is in the normal state and the Bose-Einstein condensate (BEC) state. We\napply our general theory to consider an irradiated quantum dot coupled with a\nboson bath consisting of a two-dimensional dipolar exciton gas. When the bath\nis in the BEC regime, relaxation of the Rabi oscillations is due to both\ncondensate and non-condensate fractions of the bath bosons for weak TLS-light\ncoupling and dominantly due to the non-condensate fraction for strong TLS-light\ncoupling. Our theory also shows that a phase transition of the bath from the\nnormal to the BEC state strongly influences the relaxation rate of the TLS Rabi\noscillations. The TLS relaxation rate is approximately independent of the pump\nfield frequency and monotonically dependent on the field strength when the bath\nis in the low-temperature regime of the normal phase. Phase transition of the\ndipolar exciton gas leads to a non-monotonic dependence of the TLS relaxation\nrate on both the pump field frequency and field strength, providing a\ncharacteristic signature for the detection of BEC phase transition of the\ncoupled dipolar exciton gas.",
        "positive": "Hofstadter butterflies and magnetically induced band gap quenching in\n  graphene antidot lattices: We study graphene antidot lattices (GALs) in magnetic fields. Using a\ntight-binding model and a recursive Green's function technique that we extend\nto deal with periodic structures, we calculate Hofstadter butterflies of GALs.\nWe compare the results to those obtained in a simpler gapped graphene model. A\ncrucial difference emerges in the behaviour of the lowest Landau level, which\nin a gapped graphene model is independent of magnetic field. In stark contrast\nto this picture, we find that in GALs the band gap can be completely closed by\napplying a magnetic field. While our numerical simulations can only be\nperformed on structures much smaller than can be experimentally realized, we\nfind that the critical magnetic field for which the gap closes can be directly\nrelated to the ratio between the cyclotron radius and the neck width of the\nGAL. In this way, we obtain a simple scaling law for extrapolation of our\nresults to more realistically sized structures and find resulting quenching\nmagnetic fields that should be well within reach of experiments."
    },
    {
        "anchor": "Nonmonotonic Evolution of the Blocking Temperature in Dispersions of\n  Superparamagnetic Nanoparticles: We use a Monte Carlo approach to simulate the influence of the dipolar\ninteraction on assemblies of monodisperse superparamagnetic\n${\\gamma}-Fe_{2}O_{3}$ nanoparticles. We have identified a critical\nconcentration c*, that marks the transition between two different regimes in\nthe evolution of the blocking temperature ($T_{B}$) with interparticle\ninteractions. At low concentrations (c < c*) magnetic particles behave as an\nideal non-interacting system with a constant $T_{B}$. At concentrations c > c*\nthe dipolar energy enhances the anisotropic energy barrier and $T_{B}$\nincreases with increasing c, so that a larger temperature is required to reach\nthe superparamagnetic state. The fitting of our results with classical particle\nmodels and experiments supports the existence of two differentiated regimes.\nOur data could help to understand apparently contradictory results from the\nliterature.",
        "positive": "Decoherence-avoiding spin qubits in optically active quantum dot\n  molecules: In semiconductors, the T2* coherence time of a single confined spin is\nlimited either by the fluctuating magnetic environment (via the hyperfine\ninteraction), or by charge fluctuations (via the spin-orbit interaction). We\ndemonstrate that both limitations can be overcome simultaneously by using two\nexchange-coupled electron spins that realize a single decoherence-avoiding\nqubit. Using coherent population trapping, we generate a coherent superposition\nof the singlet and triplet states of an optically active quantum-dot molecule,\nand show that the corresponding T2* may exceed 200 nanoseconds."
    },
    {
        "anchor": "Signature of Parity Anomaly: Crossover from One Half to Integer\n  Quantized Hall Conductance in a Finite Magnetic Field: The pursuit of understanding parity anomaly in condensed matter systems has\nled to significant advancements in both theoretical and experimental research\nin recent years. In this study, we explore the parity anomaly of massless Dirac\nfermions in a semimagnetic topological insulator (TI) thin film subjected to a\nfinite magnetic field. Our findings reveal an anomalous half-quantized Hall\nconductance arising from the occupied electronic states far below the Fermi\nlevel, which is directly associated with the parity anomaly. This observation\ndemonstrates a crossover from one-half quantized Hall conductance in a metallic\nphase at zero field to one or zero quantized Hall conductance in the insulating\nphase at a strong field in the presence of disorders, serving as a key\nindicator for confirming parity anomaly. Our work provides valuable insights\ninto the intricate relationship between band topology in condensed matter\nsystems and quantum anomaly in quantum field theory.",
        "positive": "A Chirality-Based Quantum Leap: Chiral degrees of freedom occur in matter and in electromagnetic fields and\nconstitute an area of research that is experiencing renewed interest driven by\nrecent observations of the chiral-induced spin selectivity (CISS) effect in\nchiral molecules and engineered nanomaterials. The CISS effect underpins the\nfact that charge transport through nanoscopic chiral structures favors a\nparticular electronic spin orientation, resulting in large room-temperature\nspin polarizations. Observations of the CISS effect suggest opportunities for\nspin control and for the design and fabrication of room-temperature quantum\ndevices from the bottom up, with atomic-scale precision. Any technology that\nrelies on optimal charge transport, including quantum devices for logic,\nsensing, and storage, may benefit from chiral quantum properties. These\nproperties can be theoretically and experimentally investigated from a quantum\ninformation perspective, which is presently lacking. There are uncharted\nimplications for the quantum sciences once chiral couplings can be engineered\nto control the storage, transduction, and manipulation of quantum information.\nThis forward-looking perspective provides a survey of the experimental and\ntheoretical fundamentals of chiral-influenced quantum effects, and presents a\nvision for their future roles in enabling room-temperature quantum\ntechnologies."
    },
    {
        "anchor": "Two-point spectroscopy of Fibonacci topoelectrical circuits: Topoelectrical circuits are meta-material realizations of topological\nfeatures of condensed matter systems. In this work, we discuss experimental\nmethods that allow a fast and straightforward detection of the spectral\nfeatures of these systems from the two-point impedance of the circuit. This\nallows to deduce the full spectrum of a topoelectrical circuit consisting of N\nsites from a single two-point measurement of the frequency resolved impedance.\nIn contrast, the standard methods rely on $N^2$ measurements of admittance\nmatrix elements with a subsequent diagonalization on a computer. We\nexperimentally test our approach by constructing a Fibonacci topoelectrical\ncircuit. Although the spectrum of this chain is fractal, i.e., more complex\nthan the spectra of periodic systems, our approach is successful in recovering\nits eigenvalues. Our work promotes the topoelectrical circuits as an ideal\nplatform to measure spectral properties of various (quasi)crystalline systems.",
        "positive": "Semiconductor Spintronics: Progress and Challenges: Brief review of the recent progress in semiconductor spintronics (theory and\nexperiment) and the current theoretical problems in it is presented. Invited\npaper at the 2006 Advanced Research Workshop \"Future Trends in\nMicroelectronics: Up to Nano Creek\" (Aghia Pelaghia, Crete, June 26-30, 2006).\nTo be published in Workshop Proceedings (Wiley)"
    },
    {
        "anchor": "Charge Density Wave Phase Transition on the Surface of Electrostatically\n  Doped Multilayer Graphene: We demonstrate that charge density wave (CDW) phase transition occurs on the\nsurface of electronically doped multilayer graphene when the Fermi level\napproaches the M points (also known as van Hove singularities where the density\nof states diverge) in the Brillouin zone of graphene band structure. The\noccurrence of such CDW phase transitions are supported by both the electrical\ntransport measurement and optical measurements in electrostatically doped\nmultilayer graphene. The CDW transition is accompanied with the sudden change\nof graphene channel resistance at T$_m$= 100K, as well as the splitting of\nRaman G peak (1580 cm$^{-1}$). The splitting of Raman G peak indicats the\nlifting of in-plane optical phonon branch degeneracy and the non-degenerate\nphonon branches are correlated to the lattice reconstructions of graphene --\nthe CDW phase transition.",
        "positive": "Excitonic valley effects in monolayer WS$_2$ under high magnetic fields: Transition-metal dichalcogenides can be easily produced as atomically thin\nsheets, exhibiting the possibility to optically polarize and read out the\nvalley pseudospin of extremely stable excitonic quasiparticles present in these\n2D semiconductors. Here, we investigate a monolayer of tungsten disulphide in\nhigh magnetic fields up to 30\\,T via photoluminescence spectroscopy at low\ntemperatures. The valley degeneracy is lifted for all optical features,\nparticularly for excitons, singlet and triplet trions, for which we determine\nthe g factor separately. While the observation of a diamagnetic shift of the\nexciton and trion resonances gives us insight into the real-space extension of\nthese quasiparticles, magnetic field induced valley polarization effects shed\nlight onto the exciton and trion dispersion relations in reciprocal space. The\nfield dependence of the trion valley polarizations is in line with the\npredicted trion splitting into singlet and triplet configurations."
    },
    {
        "anchor": "Energy levels of interacting curved nano-magnets in a frustrated\n  geometry: increasing accuracy when using finite difference methods: The accuracy of finite difference methods is related to the mesh choice and\ncell size. Concerning the micromagnetism of nano-objects, we show here that\ndiscretization issues can drastically affect the symmetry of the problem and\ntherefore the resulting computed properties of lattices of interacting curved\nnanomagnets. In this paper, we detail these effects for the multiaxe kagome\nlattice. Using the Oommf finite difference method, we propose an alternative\nway of discretizing the nanomagnet shape via a variable moment per cell scheme.\nThis method is shown to be efficient in reducing discretization effects.",
        "positive": "Suspended dry pick-up and flip-over assembly for van der Waals\n  heterostructures with ultra-clean surfaces: Van der Waals heterostructures are an excellent platform for studying\nintriguing interface phenomena, such as moir\\'e and proximity effects. Surface\nscience techniques like scanning tunneling microscopy (STM) have proven a\npowerful tool to study such heterostructures but have so far been hampered\nbecause of their high sensitivity to surface contamination. Here, we report a\ndry polymer-based assembly technique to fabricate van der Waals\nheterostructures with atomically clean surfaces. The key features of our\nsuspended dry pick-up and flip-over technique are 1) the heterostructure\nsurface never comes into contact with polymers, 2) it is entirely solvent-free,\n3) it is entirely performed in a glovebox, and 4) it only requires temperatures\nbelow 130$^{\\circ}$. By performing ambient atomic force microscopy and\natomically-resolved scanning tunneling microscopy on example heterostructures,\nwe demonstrate that we can fabricate air-sensitive heterostructures with\nultra-clean interfaces and surfaces. Due to the lack of polymer melting, the\ntechnique is further compatible with heterostructure assembly under ultra-high\nvacuum conditions, which promises ultimate heterostructure quality."
    },
    {
        "anchor": "Tree-level electron-photon interactions in graphene: Graphene's low-energy electronic excitations obey a 2+1 dimensional Dirac\nHamiltonian. After extending this Hamiltonian to include interactions with a\nquantized electromagnetic field, we calculate the amplitude associated with the\nsimplest, tree-level Feynman diagram: the vertex connecting a photon with two\nelectrons. This amplitude leads to analytic expressions for the 3D angular\ndependence of photon emission, the photon-mediated electron-hole recombination\nrate, and corrections to graphene's opacity $\\pi \\alpha$ and dynamic\nconductivity $\\pi e^2/2 h$ for situations away from thermal equilibrium, as\nwould occur in a graphene laser. We find that Ohmic dissipation in perfect\ngraphene can be attributed to spontaneous emission.",
        "positive": "Spin States Protected from Intrinsic Electron-Phonon-Coupling Reaching\n  100 ns Lifetime at Room Temperature in MoSe$_2$: We present time-resolved Kerr rotation measurements, showing spin lifetimes\nof over 100 ns at room temperature in monolayer MoSe$_2$. These long lifetimes\nare accompanied by an intriguing temperature dependence of the Kerr amplitude,\nwhich increases with temperature up to 50 K and then abruptly switches sign.\nUsing ab initio simulations we explain the latter behavior in terms of the\nintrinsic electron-phonon coupling and the activation of transitions to\nsecondary valleys. The phonon-assisted scattering of the photo-excited\nelectron-hole pairs prepares a valley spin polarization within the first few ps\nafter laser excitation. The sign of the total valley magnetization, and thus\nthe Kerr amplitude, switches as a function of temperature, as conduction and\nvalence band states exhibit different phonon-mediated inter-valley scattering\nrates. However, the electron-phonon scattering on the ps time scale does not\nprovide an explanation for the long spin lifetimes. Hence, we deduce that the\ninitial spin polarization must be transferred into spin states which are\nprotected from the intrinsic electron-phonon coupling, and are most likely\nresident charge carriers which are not part of the itinerant valence or\nconduction band states."
    },
    {
        "anchor": "Phase diagram of two dimensional electron gas in a perpendicular\n  magnetic field around Landau level filling factors \u03bd=1 and \u03bd=3: The measured melting curve $T_{m}(\\nu)$ between the crystal and liquid phases\nis analyzed using thermodynamics to extract the change of magnetization $\\Delta\nM$ as a function of the Landau level filling factor \\ $\\nu,$ near $\\nu=1$. \\ An\nexplanation of $\\Delta M$($\\nu)$ is proposed \\ in terms of Skyrmions. \\ Near\n$\\nu=3$, a Wigner crystal is the most probable solid phase, experiments\nexcluding Skyrmions.",
        "positive": "Spin-orbit torques and their associated effective fields from gigahertz\n  to terahertz: Terahertz spintronics offers the prospect of devices which are both faster\nand more energy-efficient. A promising route to achieve this goal is to exploit\ncurrent-induced spin-orbit torques. However, the high-frequency properties of\nthese quantities remain unexplored both experimentally and theoretically,\nwithin a realistic material-specific approach. Here we investigate the\ndynamical transverse components of the torques and uncover contributions\nlongitudinal to the magnetic moment capable of changing its magnitude. We show\nthat, while the torques can be drastically altered in the dynamical regime, the\neffective magnetic fields that accompany them present a frequency-independent\nbehaviour, ranging from the static limit up to the terahertz domain - including\nthe ferromagnetic resonance of the system. The outcomes of this work point to\nnew ways to control magnetic units in next-generation spintronic devices."
    },
    {
        "anchor": "Solitons in polarized double layer quantum Hall systems: A new manifestation of interlayer coherence in strongly polarized double\nlayer quantum Hall systems with total filling factor\n  $\\nu=1$ in the presence of a small or zero tunneling is theoretically\npredicted. It is shown that moving (for small tunneling) and spatially\nlocalized (for zero tunneling) stable pseudospin solitons develop which could\nbe interpreted as mobile or static charge-density excitations.\n  The possibility of their experimental observation is also discussed.",
        "positive": "Ultrafast Switching of Antiferromagnets via Spin-transfer Torque: Picosecond switching of the staggered antiferromagnetic order is shown to be\nrealizable through spin-transfer torques from a short current pulse. The\ncoupled dynamics of sublattice magnetization is mapped onto a classical\npendulum subject to gravity and a driving pulse, where switching occurs if the\npendulum acquires sufficient kinetic energy during the pulse to overcome the\nmaximum of the effective gravity potential. The optimal switching scheme is\nexplored through the dependence of switch angle and magnetic loss on the\nduration and strength of the current pulse. The physics discussed here provides\na general route towards multi-functional THz applications via the spin-transfer\ntorque in antiferromagnetic materials."
    },
    {
        "anchor": "Femtosecond formation dynamics of the spin Seebeck effect revealed by\n  terahertz spectroscopy: Understanding the transfer of spin angular momentum is essential in modern\nmagnetism research. A model case is the generation of magnons in magnetic\ninsulators by heating an adjacent metal film. Here, we reveal the initial steps\nof this spin Seebeck effect with <27fs time resolution using terahertz\nspectroscopy on bilayers of ferrimagnetic yttrium-iron garnet and platinum.\nUpon exciting the metal with an infrared laser pulse, a spin Seebeck current\n$j_\\textrm{s}$ arises on the same ~100fs time scale on which the metal\nelectrons thermalize. This observation highlights that efficient spin transfer\ncritically relies on carrier multiplication and is driven by conduction\nelectrons scattering off the metal-insulator interface. Analytical modeling\nshows that the electrons' dynamics are almost instantaneously imprinted onto\n$j_\\textrm{s}$ because their spins have a correlation time of only ~4fs and\ndeflect the ferrimagnetic moments without inertia. Applications in material\ncharacterization, interface probing, spin-noise spectroscopy and terahertz spin\npumping emerge.",
        "positive": "Coupling of three-spin qubits to their electric environment: We investigate the behavior of qubits consisting of three electron spins in\ndouble and triple quantum dots subject to external electric fields. Our model\nincludes two independent bias parameters, $\\varepsilon$ and $\\varepsilon_{M}$,\nwhich both couple to external electromagnetic fields and can be controlled by\ngate voltages applied to the quantum dot structures. By varying these\nparameters one can switch the qubit type by shifting the energies in the single\nquantum dots thus changing the electron occupancy in each dot. Starting from\nthe asymmetric resonant (ARX) exchange qubit with a (2,0,1) and (1,0,2) charge\nadmixture one can smoothly cross over to the resonant exchange (RX) qubit with\na detuned (1,1,1) charge configuration, and to the exchange-only (EO) qubit\nwith the same charge configuration but equal energy levels down to the hybrid\nqubits with (1,2,0) and (0,2,1) charge configurations. Here, ($l,m,n$)\ndescribes a configuration with $l$ electrons in the left dot, $m$ electrons in\nthe center dot, and $n$ electrons in the right dot. We first focus on random\nelectromagnetic field fluctuations, i.e., \"charge noise\", at each quantum dot\nresulting in dephasing of the qubit and provide a complete map of the resulting\ndephasing time as a function of the bias parameters. We pay special attention\nto the so-called sweet spots and double sweet spots of the system which are\nleast susceptible to noise. In the second part we investigate the coupling of\nthe qubit system to the coherent quantized electromagnetic field in a\nsuperconducting strip-line cavity and also provide a complete map of the\ncoupling strength as a function of the bias parameters. We analyze the\nasymmetric qubit-cavity coupling via $\\varepsilon$ and the symmetric coupling\nvia $\\varepsilon_{M}$."
    },
    {
        "anchor": "Controlling spin in an electronic interferometer with spin-active\n  interfaces: We consider electronic current transport through a ballistic one-dimensional\nquantum wire connected to two ferromagnetic leads. We study the effects of the\nspin-dependence of interfacial phase shifts (SDIPS) acquired by electrons upon\nscattering at the boundaries of the wire. The SDIPS produces a spin splitting\nof the wire resonant energies which is tunable with the gate voltage and the\nangle between the ferromagnetic polarizations. This property could be used for\nmanipulating spins. In particular, it leads to a giant magnetoresistance effect\nwith a sign tunable with the gate voltage and the magnetic field applied to the\nwire.",
        "positive": "Observation of a controllable PI-junction in a 3-terminal Josephson\n  device: Recently Baselmans et al. [Nature, 397, 43 (1999)] showed that the direction\nof the supercurrent in a superconductor/normal/superconductor Josephson\njunction can be reversed by applying, perpendicularly to the supercurrent, a\nsufficiently large control current between two normal reservoirs. The novel\nbehavior of their 4-terminal device (called a controllable PI-junction) arises\nfrom the nonequilibrium electron energy distribution established in the normal\nwire between the two superconductors. We have observed a similar supercurrent\nreversal in a 3-terminal device, where the control current passes from a single\nnormal reservoir into the two superconductors. We show theoretically that this\nbehavior, although intuitively less obvious, arises from the same\nnonequilibrium physics present in the 4-terminal device. Moreover, we argue\nthat the amplitude of the PI-state critical current should be at least as large\nin the 3-terminal device as in a comparable 4-terminal device."
    },
    {
        "anchor": "Two-dimensional nodal-loop half metal in monolayer MnN: Two-dimensional (2D) materials with nodal-loop band crossing have been\nattracting great research interest. However, it remains a challenge to find 2D\nnodal loops that are robust against spin-orbit coupling (SOC) and realized in\nmagnetic states. Here, based on first-principles calculations and theoretical\nanalysis, we predict that monolayer MnN is a 2D nodal-loop half metal with\nfully spin polarized nodal loops. We show that monolayer MnN has a\nferromagnetic ground state with out-of-plane magnetization. Its band structure\nshows half metallicity with three low-energy bands belonging to the same spin\nchannel. The crossing between these bands forms two concentric nodal loops\ncentered around the $\\Gamma$ point near the Fermi level. Remarkably, the nodal\nloops and their spin polarization are robust under SOC, due to the protection\nof a mirror symmetry. We construct an effective model to characterize the fully\npolarized emergent nodal-loop fermions. We also find that a uniaxial strain can\ninduce a loop transformation from a localized single loop circling around\n$\\Gamma$ to a pair of extended loops penetrating the Brillouin zone.",
        "positive": "Surface exciton polaritons: a promising mechanism for sensing\n  applications: The possibility of constructing a surface exciton polariton (SEP) based\nsensor at room temperature is explored. The proposed SEP sensor is based on the\nKretschmann-Raether configuration of conventional surface plasmon resonance\n(SPR) sensor, where the metal thin film was replaced by the J-aggregate cyanine\ndye film. The excitation of SEP results in a strong electric field at the\ninterface of TDBC and analyte, and exponentially decaying into the analyte,\nwhich is sensitive to the refractive index variations of analyte. The\nsensitivity of 118.1818 $^\\circ/\\text{RIU}$ (140.4286 $^\\circ/\\text{RIU}$) was\nachieved for the proposed SEP sensor within the refractive index range\n1.0-1.001 (1.33-1.36) of gaseous analyte (aqueous solutions), which is about 2\n(3.5) times higher than that of conventional gold-based SPR sensor. The\nsignificant superiority of the SEP sensor in sensitivity revealing SEP as a new\npromising mechanism for sensing applications."
    },
    {
        "anchor": "Monte Carlo study of the exchange bias effect in Co/CoO core-shell\n  nanowires: We study the magnetic properties of cylindrical ferromagnetic core -\nantiferromagnetic shell nanowires using Monte Carlo simulations and a classical\nHeisenberg Hamiltonian in order to elucidate the impact of the oxidized shell\non the magnetic properties and the magnetization reversal mechanism. We find\nthat the coupling to the antiferromagnetic shell leads to suppression of the\ncoercivity and emergence of a weak exchange bias effect. Comparison of the\nmagnetization reversal mechanism in the bare and the surface-oxidized nanowire\nreveals that the domain wall propagation and annihilation remains the dominant\nreversal mechanism in surface oxidized nanowires as in their ferromagnetic\ncounterparts. However, the interface exchange coupling introduces a secondary\nreversal mechanism activated in the central part of the wire with\ncharacteristics of coherent rotation, which acts in synergy to wall propagation\nleading to enhancement of the wall mobility. This effect is more pronounced in\nnanowires with large exchange bias values and is attributed to the\nuncompensated interface moments that act as nucleation centers for\nmagnetization reversal. Our results are in good agreement with recent\nmeasurements in Co and Co/CoO nanowires.",
        "positive": "Quantum site percolation on triangular lattice and the integer quantum\n  Hall effect: Generic classical electron motion in a strong perpendicular magnetic field\nand random potential reduces to the bond percolation on a square lattice. Here\nwe point out that for certain smooth 2D potentials with 120 degrees rotational\nsymmetry this problem reduces to the site percolation on a triangular lattice.\nWe use this observation to develop an approximate analytical description of the\ninteger quantum Hall transition. For this purpose we devise a quantum\ngeneralization of the real-space renormalization group (RG) treatment of the\nsite percolation on the triangular lattice. In quantum case, the RG\ntransformation describes the evolution of the distribution of the $3\\times 3$\nscattering matrix at the sites. We find the fixed point of this distribution\nand use it to determine the critical exponent, $\\nu$, for which we find the\nvalue $\\nu \\approx 2.3-2.76$. The RG step involves only a single Hikami box,\nand thus can serve as a minimal RG description of the quantum Hall transition."
    },
    {
        "anchor": "Memory and correlation effects in the exciton-phonon kinetics: Memory and correlation effects in the interband absorption from quantum wells\ndue to exciton-phonon dynamics are investigated. They are traced back to the\nfrequency dependence and matrix character of the self energy arising in a 2nd\nBorn theory. It is found that interpeak absorption increases with respect to\nthe case in which this memory and correlation effects are neglected.",
        "positive": "Magnetic field noise analyses generated by the interactions between a\n  nitrogen vacancy center diamond and surface and bulk impurities: We investigated the mechanism of magnetic noise due to both surface and bulk\nimpurities. For surface noise, we apply the Langevin method to spin fluctuation\ntheory to calculate the noise for paramagnetic surface impurities absorbed in a\nthin layer of water. We find that the mechanisms generating noise are spin flip\nand spin precession which depend on impurity spin relaxation and spin\nprecession time. For the bulk noise, we consider carbon-13 and nitrogen as\nimpurities and employ the correlated-cluster expansion to calculate noise.\nCarbon-13 noise is a few orders of magnitude larger than nitrogen due to the\nhigher impurity density in the typical NV center diamond system. We also find\nthat the noise in the secular approximation underestimates noise under low\napplied magnetic field. Overall, the major source of magnetic field noise is\nspin precession noise, which is more than five orders of magnitude larger than\nthe spin flip noise."
    },
    {
        "anchor": "Non-Abelian spin-orbit gauge: Persistent spin helix and quantum square\n  ring: We re-express the Rashba and Dresselhaus interactions as non-Abelian\nspin-orbit gauges and provide a new perspective in understanding the persistent\nspin helix [Phys. Rev. Lett. 97, 236601 (2006)]. A spin-orbit interacting\nsystem can be transformed into a free electron gas in the equal-strength\nRashba-Dresselhaus [001] linear model, the Dresselhaus [110] linear model, and\na one-dimensional system. A general tight-binding Hamiltonian for non-uniform\nspin-orbit interactions and hoppings along arbitrary directions, within the\nframework of finite difference method, is obtained. As an application based on\nthis Hamiltonian, a quantum square ring in contact with two ideal leads is\nfound to exhibit four states, insulating, spin-filtering, spin-flipping, and\nspin-keeping states.",
        "positive": "Optical properties and electromagnetic modes of Weyl semimetals: We present systematic theoretical studies of both bulk and surface\nelectromagnetic eigenmodes, or polaritons, in Weyl semimetals. We derive the\ntensors of bulk and surface conductivity taking into account all possible\ncombinations of the optical transitions involving bulk and surface electron\nstates. We show how information about electronic structure of Weyl semimetals,\nsuch as position and separation of Weyl nodes, Fermi energy, and Fermi arc\nsurface states, can be unambiguously extracted from measurements of the\ndispersion, transmission, reflection, and polarization of electromagnetic\nwaves."
    },
    {
        "anchor": "Pseudo-diffusive magnetotransport in graphene: Transport properties through wide and short ballistic graphene junctions are\nstudied in the presence of arbitrary dopings and magnetic fields. No dependence\non the magnetic field is observed at the Dirac point for any current cumulant,\njust as in a classical diffusive system, both in normal-graphene-normal and\nnormal-graphene-superconductor junctions. This pseudo-diffusive regime is\nhowever extremely fragile respect to doping at finite fields. We identify the\ncrossovers to a field-suppressed and a normal ballistic transport regime in the\nmagnetic field - doping parameter space, and provide a physical interpretation\nof the phase diagram. Remarkably, pseudo-diffusive transport is recovered away\nfrom the Dirac point in resonance with Landau levels at high magnetic fields.",
        "positive": "Intrinsic Gap of the nu=5/2 Fractional Quantum Hall State: The fractional quantum Hall effect is observed at low field, in a regime\nwhere the cyclotron energy is smaller than the Coulomb interaction. The nu=5/2\nexcitation gap is measured to be 262+/-15 mK at ~2.6 T, in good agreement with\nprevious measurements performed on samples with similar mobility, but with\nelectronic density larger by a factor of two. The role of disorder on the\nnu=5/2 gap is examined. Comparison between experiment and theory indicates that\na large discrepancy remains for the intrinsic gap extrapolated from the\ninfinite mobility (zero disorder) limit. In contrast, no such large discrepancy\nis found for the nu=1/3 Laughlin state. The observation of the nu=5/2 state in\nthe low-field regime implies that inclusion of non-perturbative Landau level\nmixing may be necessary to better understand the energetics of half-filled\nfractional quantum hall liquids."
    },
    {
        "anchor": "Environmental effects in the third moment of voltage fluctuations in a\n  tunnel junction: We present the first measurements of the third moment of the voltage\nfluctuations in a conductor. This technique can provide new and complementary\ninformation on the electronic transport in conducting systems. The measurement\nwas performed on non-superconducting tunnel junctions as a function of voltage\nbias, for various temperatures and bandwidths up to 1GHz. The data demonstrate\nthe significant effect of the electromagnetic environment of the sample.",
        "positive": "Determination of effective mechanical properties of a double-layer beam\n  by means of a nano-electromechanical transducer: We investigate the mechanical properties of a doubly-clamped, double-layer\nnanobeam embedded into an electromechanical system. The nanobeam consists of a\nhighly pre-stressed silicon nitride and a superconducting niobium layer. By\nmeasuring the mechanical displacement spectral density both in the linear and\nthe nonlinear Duffing regime, we determine the pre-stress and the effective\nYoung's modulus of the nanobeam. An analytical double-layer model\nquantitatively corroborates the measured values. This suggests that this model\ncan be used to design mechanical multilayer systems for electro- and\noptomechanical devices, including materials controllable by external parameters\nsuch as piezoelectric, magnetrostrictive, or in more general multiferroic\nmaterials."
    },
    {
        "anchor": "Stationary transport in mesoscopic hybrid structures with contacts to\n  superconducting and normal wires. A Green's function approach for\n  multiterminal setups: We generalize the representation of the real time Green's functions\nintroduced by Langreth and Nordlander [Phys. Rev. B 43 2541 (1991)] and Meir\nand Wingreen [Phys. Rev. Lett. 68 2512 (1992)] in stationary quantum transport\nin order to study problems with hybrid structures containing normal (N) and\nsuperconducting (S) pieces. We illustrate the treatment in a S-N junction under\na stationary bias and investigate in detail the behavior of the equilibrium\ncurrents in a normal ring threaded by a magnetic flux with attached\nsuperconducting wires at equilibrium. We analyze the flux sensitivity of the\nAndreev states and we show that their response is equivalent to the one\ncorresponding to the Cooper pairs with momentum q=0 in an isolated\nsuperconducting ring.",
        "positive": "Dc Electrical Current Generated by Upstream Neutral Modes: Quantum Hall phases are gapped in the bulk but support chiral edge modes,\nboth charged and neutral. Here we consider a circuit where the path from the\nsource of electric current to the drain necessarily passes through a segment\nconsisting solely of neutral modes. We find that upon biasing the source, a dc\nelectric current is detected at the drain, provided there is backscattering\nbetween counter-propagating modes under the contacts placed in certain\nlocations. Thus, neutral modes carry information that can be used to nonlocally\nreconstruct a dc charge current. Our protocol can be used to detect any neutral\nmode that counterpropagates with respect to all charge modes. Our protocol\napplies not only to the edge modes of a quantum Hall system, but also to\nsystems that have neutral modes of non-quantum Hall origin. We conclude with a\npossible experimental realization of this phenomenon."
    },
    {
        "anchor": "Critical Peeling of Tethered Nanoribbons: The peeling of an immobile adsorbed membrane is a well known problem in\nengineering and macroscopic tribology. In the classic setup, picking up at one\nextreme and pulling off results in a peeling force that is a decreasing\nfunction of the pickup angle. As one end is lifted, the detachment front\nretracts to meet the immobile tail. At the nanoscale, interesting situations\narise with the peeling of graphene nanoribbons (GNRs) on gold, as realized,\ne.g., by atomic force microscopy. The nanosized system shows a constant-force\nsteady peeling regime, where the tip lifting h produces no retraction of the\nribbon detachment point, and just an advancement h of the free tail end. This\nis opposite to the classic case, where the detachment point retracts and the\ntail end stands still. Here we characterise, by analytical modeling and\nnumerical simulations, a third, experimentally relevant, setup where the\nnanoribbon, albeit structurally lubric, does not have a freely moving tail end,\nwhich is instead elastically tethered. Surprisingly, novel nontrivial scaling\nexponents appear that regulate the peeling evolution. As the detachment front\nretracts and the tethered tail is stretched, power laws of h characterize the\nshrinking of the adhered length the growth of peeling force and the peeling\nangle. These exponents precede the final total detachment as a critical point,\nwhere the entire ribbon eventually hangs suspended between the tip and\ntethering spring. These analytical predictions are confirmed by realistic MD\nsimulations, retaining the full atomistic description, also confirming their\nsurvival at finite experimental temperatures.",
        "positive": "Special electronic structures and quantum conduction of B/P co-doping\n  carbon nanotubes under electric field using the first principle: Boron (B)/phosphorus (P) doped single wall carbon nanotubes (B-PSWNTs) are\nstudied by using the First- Principle method based on density function theory\n(DFT). Mayer bond order, band structure, electrons density and density of\nstates are calculated. It concludes that the B-PSWNTs have special band\nstructure which is quite different from BN nanotubes, and that metallic carbon\nnanotubes will be converted to semiconductor due to boron/phosphorus co-doping\nwhich breaks the symmetrical structure. The bonding forms in B-PSWNTs are\ninvestigated in detail. Besides, Mulliken charge population and the quantum\nconductance are also calculated to study the quantum transport characteristics\nof B-PSWNT hetero-junction. It is found that the position of p-n junction in\nthis hetero-junction will be changed as the applied electric field increase and\nit performs the characteristics of diode."
    },
    {
        "anchor": "Low-damping transmission of spin waves through YIG/Pt-based layered\n  structures for spin-orbit-torque applications: We show that in YIG-Pt bi-layers, which are widely used in experiments on the\nspin transfer torque and spin Hall effects, the spin-wave amplitude\nsignificantly decreases in comparison to a single YIG film due to the\nexcitation of microwave eddy currents in a Pt coat. By introducing a novel\nexcitation geometry, where the Pt layer faces the ground plane of a microstrip\nline structure, we suppressed the excitation of the eddy currents in the Pt\nlayer and, thus, achieved a large increase in the transmission of the\nDamon-Eshbach surface spin wave. At the same time, no visible influence of an\nexternal dc current applied to the Pt layer on the spin-wave amplitude in the\nYIG-Pt bi-layer was observed in our experiments with YIG films of micrometer\nthickness.",
        "positive": "Topological ordering in the Majorana Toric Code: At zero temperature, a two-dimensional lattice of Majorana zero modes on\nmesoscopic superconducting islands exhibits a topologically-ordered toric code\nphase. Recently, a Landau field theory was used to describe the different\nphases of the aforementioned system and the phase-transitions separating them.\nWhile the field theory provides details on the properties of the system close\nto the phase-transitions, signatures of topological ordering in the different\nphases have not been computed. This is the primary goal of the current work. We\ndescribe a lattice gauge theory of the Majorana toric code in terms of\n$\\mathrm{U}(1)$ matter fields coupled to an emergent $\\mathbb{Z}_2$ gauge\nfield. Subsequently, we use a generalized Wilson-loop order-parameter, the\nequal-time Fredenhagen-Marcu order parameter, to characterize the topological\nordering in the different phases. Our computation provides evidence of the\ntoric code phase both in the Mott insulator and the charge-$2e$ superconductor\nphases, while showing that the toric code phase disappears in the charge-$e$\nsuperconductor phase. In addition, we perturbatively analyze the influence of\nCooper pair tunneling on the topological gap of the toric code in the limit of\nstrong charging energy and show that the toric code phase is, in fact,\nstabilized by the Cooper pair tunneling. Our results are relevant for\nexperimental realizations of the Majorana toric code."
    },
    {
        "anchor": "Proximity-induced Majorana hinge modes in antiferromagnetic topological\n  insulators: We propose a realization of chiral Majorana modes propagating on the hinges\nof a 3D antiferromagnetic topological insulator, which was recently\ntheoretically predicted and experimentally confirmed in the tetradymite-type\n$\\mathrm{MnBi_2Te_4}$-related ternary chalgogenides. These materials consist of\nferromagnetically ordered 2D layers, whose magnetization direction alternates\nbetween neighboring layers, forming an antiferromagnetic order. Besides\nsurfaces with a magnetic gap, there also exsist gapless surfaces with a single\nDirac cone, which can be gapped out when proximity coupled to an $s$-wave\nsuperconductor. On the sharing edges between the two types of gapped surfaces,\nthe chiral Majorana modes emerge. We further propose experimental signatures of\nthese Majoana hinge modes in terms of two-terminal conductance measurements.",
        "positive": "Highly indistinguishable single photons from incoherently and coherently\n  excited GaAs quantum dots: Semiconductor quantum dots are converging towards the demanding requirements\nof photonic quantum technologies. Among different systems, quantum dots with\ndimensions exceeding the free-exciton Bohr radius are appealing because of\ntheir high oscillator strengths. While this property has received much\nattention in the context of cavity quantum electrodynamics, little is known\nabout the degree of indistinguishability of single photons consecutively\nemitted by such dots and on the proper excitation schemes to achieve high\nindistinguishability. A prominent example is represented by GaAs quantum dots\nobtained by local droplet etching, which recently outperformed other systems as\ntriggered sources of entangled photon pairs. On these dots, we compare\ndifferent single-photon excitation mechanisms, and we find (i) a \"phonon\nbottleneck\" and poor indistinguishability for conventional excitation via\nexcited states and (ii) photon indistinguishablilities above 90% for both\nstrictly resonant and for incoherent acoustic- and optical-phonon-assisted\nexcitation. Among the excitation schemes, optical phonon-assisted excitation\nenables straightforward laser rejection without a compromise on the source\nbrightness together with a high photon indistinguishability."
    },
    {
        "anchor": "Observation of anomalous non-Ohmic transport in current-driven\n  nanostructures: Sufficiently large electric current applied to metallic nanostructures can\nbring them far out-of-equilibrium, resulting in non-Ohmic behaviors\ncharacterized by current-dependent resistance. We experimentally demonstrate a\nlinear dependence of resistance on current in microscopic thin-film metallic\nwires at cryogenic temperatures, and show that our results are inconsistent\nwith common non-Ohmic mechanisms such as Joule heating. As the temperature is\nincreased, the linear dependence becomes smoothed out, resulting in the\ncrossover to behaviors consistent with Joule heating. A plausible explanation\nfor the observed behaviors is the strongly non-equilibrium distribution of\nphonons generated by the current. Analysis based on this interpretation\nsuggests that the observed anomalous current-dependent resistance can provide\ninformation about phonon transport and electron-phonon interaction at\nnanoscale. The ability to control the properties of phonons generated by\ncurrent can lead to new routes for the optimization of thermal properties of\nelectronic nanodevices.",
        "positive": "Diamagnetism and suppression of screening as hallmarks of electron-hole\n  pairing in a double layer graphene system: We study how the electron-hole pairing reveals itself in the response of a\ndouble layer graphene system to the vector and scalar potentials. Electron-hole\npairing results in a rigid (London)relation between the current and the\ndifference of vector potentials in two adjacent layers. The diamagnetic effect\ncan be observed in multiple connected systems in the magnetic field parallel to\nthe graphene layers. Such an effect would be considered as a hallmark of the\nelectron-hole pairing, but the value of the effect is extremely small.\nElectron-hole pairing significantly changes the response to the scalar\npotential, as well. It results in a complete (at zero temperature) or partial\n(at finite temperature) suppression of screening of the electric field of a\ntest charge situated at some distance to the double layer system. A strong\nincrease of the electric field induced by the test charge under decrease in\ntemperature can be considered as a spectacular hallmark of the electron-hole\npairing."
    },
    {
        "anchor": "Physical Origin of Current Partition at a Topological Trifurcation: In gated bilayer graphene, topological zero-line modes (ZLMs) appear along\nlines separating regions with opposite valley Hall topologies. Although it is\nexperimentally difficult to design the electric gates to realize ZLMs due to\nthe extremely challenging techniques, twisted bilayer graphene provides a\nnatural platform to produce ZLMs in the presence of uniform electric field. In\nthis Letter, we develop a set of wavepacket dynamics, which can be utilized to\ncharacterize various gapless edge modes and can quantitatively reproduce the\nelectronic transport properties at topological intersections. To our surprise,\nin the minimally twisted bilayer graphene where a topological trifurcation\nintersection naturally arises, we show that the counterintuitive current\npartition (i.e., the direct transport propagation) originates from the\nmicroscopic mechanism \"bypass jump\". Our method can be applied to understand\nthe microscopic pictures of the electronic transport features of all kinds of\ntopological states.",
        "positive": "Counting statistics of single-electron transport in a quantum dot: We have measured the full counting statistics (FCS) of current fluctuations\nin a semiconductor quantum dot (QD) by real-time detection of single electron\ntunneling with a quantum point contact (QPC). This method gives direct access\nto the distribution function of current fluctuations. Suppression of the second\nmoment (related to the shot noise) and the third moment (related to the\nasymmetry of the distribution) in a tunable semiconductor QD is demonstrated\nexperimentally. With this method we demonstrate the ability to measure very low\ncurrent and noise levels."
    },
    {
        "anchor": "Suppression of Spin-Orbit Scattering in Strong-Disordered Gold\n  Nanojunctions: We discovered that spin-orbit scattering in strong-disordered gold\nnanojunctions is strongly suppressed relative to that in weak-disordered gold\nthin films. This property is unusual because in weak-disordered films,\nspin-orbit scattering increases with disorder. Granularity and freezing of\nspin-orbit scattering inside the grains explains the suppression of spin-orbit\nscattering. We propose a generalized Elliot-Yafet relation that applies to\nstrong-disordered granular regime.",
        "positive": "Fast and accurate shot noise measurements on atomic-size junctions in\n  the MHz regime: Shot noise measurements on atomic and molecular junctions provide rich\ninformation about the quantum transport properties of the junctions and on the\ninelastic scattering events taking place in the process. Dissipation at the\nnanoscale, a problem of central interest in nano-electronics, can be studied in\nits most explicit and simplified form. Here, we describe a measurement\ntechnique that permits extending previous noise measurements to a much higher\nfrequency range, and to much higher bias voltage range, while maintaining a\nhigh accuracy in noise and conductance. We also demonstrate the advantages of\nhaving access to the spectral information for diagnostics."
    },
    {
        "anchor": "Observation of a topological 3D Dirac semimetal phase in high-mobility\n  Cd3As2: Experimental identification of three-dimensional (3D) Dirac semimetals in\nsolid state systems is critical for realizing exotic topological phenomena and\nquantum transport such as the Weyl phases, high temperature linear quantum\nmagnetoresistance and topological magnetic phases. Using high resolution\nangle-resolved photoemission spectroscopy, we performed systematic electronic\nstructure studies on well-known compound Cd3As2. For the first time, we observe\na highly linear bulk Dirac cone located at the Brillouin zone center projected\nonto the (001) surface which is consistent with a 3D Dirac semimetal phase in\nCd3As2. Remarkably, an unusually high Dirac Fermion velocity up to 10.2\n\\textrm{\\AA}{\\cdot}$eV (1.5 \\times 10^{6} ms^-1) is seen in samples where the\nmobility far exceeds 40,000 cm^2/V.s suggesting that Cd3As2 can be a promising\ncandidate as a hypercone analog of graphene in many device-applications which\ncan also incorporate topological quantum phenomena in a large gap setting. Our\nexperimental identification of this novel topological 3D Dirac semimetal phase,\ndistinct from a 3D topological insulator phase discovered previously, paves the\nway for exploring higher dimensional relativistic physics in bulk transport and\nfor realizing novel Fermionic matter such as a Fermi arc nodal metal.",
        "positive": "Tunable Thermal Energy Transport across Diamond Membranes and Diamond-Si\n  Interfaces by Nanoscale Graphoepitaxy: The development of electronic devices, especially those that involve\nheterogeneous integration of materials, has led to increased challenges in\naddressing their thermal operational-temperature demands. The heat flow in\nthese systems is significantly influenced or even dominated by thermal boundary\nresistance at interface between dissimilar materials. However, controlling and\ntuning heat transport across an interface and in the adjacent materials has so\nfar drawn limited attention. In this work, we grow chemical-vapor-deposited\n(CVD) diamond on silicon substrates by graphoepitaxy and experimentally\ndemonstrate tunable thermal transport across diamond membranes and\ndiamond-silicon interfaces. We observed the highest diamond-silicon thermal\nboundary conductance (TBC) measured to date and increased diamond thermal\nconductivity due to strong grain texturing in the diamond near the interface.\nAdditionally, non-equilibrium molecular-dynamics (NEMD) simulations and a\nLandauer approach are used to understand the diamond-silicon TBC. These\nfindings pave the way for tuning or increasing thermal conductance in\nheterogeneously integrated electronics that involve polycrystalline materials\nand will impact applications including electronics thermal management and\ndiamond growth."
    },
    {
        "anchor": "Observation of biradical spin coupling through hydrogen bonds: Investigation of intermolecular electron spin interaction is of fundamental\nimportance in both science and technology.Here, radical pairs of all-trans\nretinoic acid molecules on Au(111) are created using an ultra-low temperature\nscanning tunneling microscope. Antiferromagnetic coupling between two radicals\nis identified by magnetic-field dependent spectroscopy.The measured exchange\nenergies are from 0.1 to 1.0 meV. The biradical spin coupling is mediated\nthrough O-H$\\cdots$O hydrogen bonds, as elucidated from analysis combining\ndensity functional theory calculation and a modern version of valence bond\ntheory.",
        "positive": "Vacuum polarization of charged massless fermions in Coulomb and\n  Aharonov--Bohm fields: Vacuum polarization of charged massless fermions is investigated in the\nsuperposition of Coulomb and Aharonov--Bohm (AB) potentials in 2+1 dimensions.\nFor this purpose we construct the Green function of the two-dimensional Dirac\nequation with Coulomb and AB potentials (via the regular and irregular\nsolutions of the radial Dirac equation) and calculate the vacuum polarization\ncharge density in these fields in the so-called subcritical and supercritical\nregimes.\n  The role of the self-adjoint extension parameter is discussed in terms of the\nphysics of problem. We hope that our results will be helpful in the more deep\nunderstanding the fundamental problem of quantum electrodynamics and can be\napplied to the problems of charged impurity screening in graphene with taking\ninto consideration the electron spin."
    },
    {
        "anchor": "Chiral limits and effect of light on the Hofstadter butterfly in twisted\n  bilayer graphene: We study the magnetic field induced Hofstadter butterfly in twisted bilayer\ngraphene (TBG) in various kinds of situations. First, we study the equilibrium\ncase and identify the interlayer hopping processes that are most crucial for\nthe appearance of a Hofstadter butterfly. Surprisingly, the hopping processes\nthat are important for the appearance of the Hofstadter butterfly can be\ncategorized as AA stacking type - that is interlayer hoppings between\nequivalent sublattices. This is in contrast to AB/BA-type hoppings that are\nimportant for the appearance of flat bands in magic angle TBG and were\ndiscussed in [Phys. Rev. Lett. 122, 106405 (2019)]. We also find that if\nAB-type interlayer-hopping processes are turned off the resulting model is\nchiral but differs from the model discussed in \\cite{Tarnopolsky}. Therefore,\nTBG has two separate chiral limits - one of them is important to understand the\nformation of flat bands and the other for the Hofstadter butterfly. Taking this\nas motivation we discuss how the role of AA-type hoppings in combination with\nlattice relaxation effects can make individual Landau levels slightly harder to\nresolve in an experimental setting than one would expect from a non-relaxed\nlattice setting. Finally, we consider the impact of different forms of light on\nthe fractal structure of the butterfly. Particularly, we study the impact of\ncircularly polarized light and longitudinal light originating from a waveguide.\nAs the system is exposed to circularly polarized light we find butterflies with\nincreasingly pronounced asymmetry with respect to energy $E=0$. This is due to\nthe introduction of a gap term that breaks the chiral symmetries for both of\nthe two chiral limits mentioned above. Lastly, we study the effect of\nlongitudinal light that can be produced at the exit of a waveguide, in a\nslightly simplified model. Here, we find ...",
        "positive": "Conductance of p-n-p graphene structures with 'air-bridge' top gates: We have fabricated graphene devices with a top gate separated from the\ngraphene layer by an air gap--a design which does not decrease the mobility of\ncharge carriers under the gate. This gate is used to realise p-n-p structures\nwhere the conducting properties of chiral carriers are studied. The band\nprofile of the structures is calculated taking into account the specifics of\nthe graphene density of states and is used to find the resistance of the p-n\njunctions expected for chiral carriers. We show that ballistic p-n junctions\nhave larger resistance than diffusive ones. This is caused by suppressed\ntransmission of chiral carriers at angles away from the normal to the junction."
    },
    {
        "anchor": "Quantum Entangled Dark Solitons Formed by Ultracold Atoms in Optical\n  Lattices: Inspired by experiments on Bose-Einstein condensates in optical lattices, we\nstudy the quantum evolution of dark soliton initial conditions in the context\nof the Bose-Hubbard Hamiltonian. An extensive set of quantum measures is\nutilized in our analysis, including von Neumann and generalized quantum\nentropies, quantum depletion, and the pair correlation function. We find that\nquantum effects cause the soliton to fill in. Moreover, soliton-soliton\ncollisions become inelastic, in strong contrast to the predictions of\nmean-field theory. These features show that the lifetime and collision\nproperties of dark solitons in optical lattices provide clear signals of\nquantum effects.",
        "positive": "Observation of topological states residing at step edges of WTe2: Topological states emerge at the boundary of solids as a consequence of the\nnontrivial topology of the bulk. Recently, theory predicts a topological edge\nstate on single layer transition metal dichalcogenides with 1T' structure.\nHowever, its existence still lacks experimental proof. Here, we report the\ndirect observations of the topological states at the step edge of WTe2 by\nspectroscopic-imaging scanning tunneling microscopy. A one-dimensional\nelectronic state residing at the step edge of WTe2 is observed, which has a\nspatial extension of about 2.5 nm. First principles calculations rigorously\nverify the edge state has a topological origin, and its topological nature is\nunaffected by the presence of the substrate. Our study supports the existence\nof topological edge states in 1T'-WTe2, which may envision in-depth study of\nits topological physics and device applications."
    },
    {
        "anchor": "Minimal excitation states of electrons in one-dimensional wires: A strategy is proposed to excite particles from a Fermi sea in a noise-free\nfashion by electromagnetic pulses with realistic parameters. We show that by\nusing quantized pulses of simple form one can suppress the particle-hole pairs\nwhich are created by a generic excitation. The resulting many-body states are\ncharacterized by one or several particles excited above the Fermi surface\naccompanied by no disturbance below it. These excitations carry charge which is\ninteger for noninteracting electron gas and fractional for Luttinger liquid.\nThe operator algebra describing these excitations is derived, and a method of\ntheir detection which relies on noise measurement is proposed.",
        "positive": "SPT 2-Channel Kondo Model in the Structure of Normal Metal/Quantum\n  Dot/DIII-class Topological Superconductor: We investigate the Kondo effect in a structure which is constructed by\nembedding one quantum dot between a normal metal and a \\emph{DIII}-class\ntopological superconductor supporting Majorana doublets at its ends. It is\nobserved that Kondo correlation occurs between the localized state in the dot\nand two continuum states simultaneously, i.e., the continuum state in the metal\nand the continuum Andreev reflection state between the metal and topological\nsuperconductor. As a result, the Kondo model Hamiltonian is topologically\nprotected by the $SU(2)_s\\rtimes Z_2^T$ symmetry. Besides, the Kondo\ntemperature has an opportunity to present three forms in turn, following the\nenhancement of the coupling between the dot and Majorana doublet. This\nphenomenon exactly reflects the special role of Majorana doublet in tuning the\nKondo effect."
    },
    {
        "anchor": "Effect of Dephasing on Electron Transport in a Molecular Wire: Green's\n  Function Approach: The effect of dephasing on electron transport through a benzene molecule is\ncarefully examined using a phenomenological model introduced by B\\\"{u}ttiker.\nWithin a tight-binding framework all the calculations are performed based on\nthe Green's function formalism. We investigate the influence of dephasing on\ntransmission probability and current-voltage characteristics for three\ndifferent configurations ({\\em ortho}, {\\em meta} and {\\em para}) of the\nmolecular system depending on the locations of two contacting leads. The\npresence of dephasing provides a significant change in the spectral properties\nof the molecule and exhibits several interesting patterns that have so far\nremain unexplored.",
        "positive": "Localization renormalization and quantum Hall systems: The obstruction to constructing localized degrees of freedom is a signature\nof several interesting condensed matter phases. We introduce a localization\nrenormalization procedure that harnesses this property, and apply our method to\ndistinguish between topological and trivial phases in quantum Hall and Chern\ninsulators. By iteratively removing a fraction of maximally-localized\northogonal basis states, we find that the localization length in the residual\nHilbert space exhibits a power-law divergence as the fraction of remaining\nstates approaches zero, with an exponent of $\\nu=0.5$. In sharp contrast, the\nlocalization length converges to a system-size-independent constant in the\ntrivial phase. We verify this scaling using a variety of algorithms to truncate\nthe Hilbert space, and show that it corresponds to a statistically self-similar\nexpansion of the real-space projector. This result accords with a\nrenormalization group picture and motivates the use of localization\nrenormalization as a versatile numerical diagnostic for quantum Hall systems."
    },
    {
        "anchor": "Composite-fermion description of rotating Bose gases at low angular\n  momenta: We study the composite fermion construction at and below the single vortex\n($L=N$) state of weakly interacting rotating Bose gases, presenting a new\nmethod for handling the large number of derivatives typically occurring via the\nSlater determinant. Remarkably, the CF wave function at $L=N$ becomes {\\em\nexact} in the large $N$ limit, even though this construction is not, {\\em a\npriori}, expected to work in the low angular momentum regime. This implies an\ninteresting mathematical identity which may be useful in other contexts.",
        "positive": "Experimental constraints and a possible quantum Hall state at $\u03bd=5/2$: Several topological orders have been proposed to explain the quantum Hall\nplateau at $\\nu=5/2$. The observation of an upstream neutral mode on the sample\nedge [Bid et al., Nature (London) 466, 585 (2010)] supports the non-Abelian\nanti-Pfaffian state. On the other hand, the tunneling experiments [Radu et al.,\nScience 320, 899 (2008); Lin et al., Phys. Rev. B 85, 165321 (2012); Baer et\nal., arXiv:1405.0428] favor the Halperin 331 state which exhibits no upstream\nmodes. We find a topological order, compatible with the results of both types\nof experiments. That order allows both finite and zero spin polarizations. It\nis Abelian but its signatures in Aharonov-Bohm interferometry can be similar to\nthose of the Pfaffian and anti-Pfaffian states."
    },
    {
        "anchor": "Radiative cooling induced by time-symmetry breaking in\n  periodically-driven systems: We theoretically study the thermal relaxation of many-body systems under the\naction of oscillating external fields. When the magnitude or the orientation of\na field is modulated around values where the pairwise heat-exchange\nconductances depend non-linearly on this field, we demonstrate that the time\nsymmetry is broken during the evolution of temperatures over a modulation\ncycle. We predict that this asymmetry enables a pumping of heat which can be\nused to cool down faster the system. This effect is illustrated through\ndifferent magneto-optical systems under the action of an oscillating magnetic\nfield.",
        "positive": "Inelastic light scattering and the off-resonance approximation: Inelastic (Raman) light scattering intensities for a 42-electron quantum dot\nunder off-resonance conditions and in different spin and angular momentum\nchannels are computed in order to test whether final collective states become\nthe dominant peaks in the process. The results of the calculations set a limit\nto the spread use of the off-resonant approximation for the theoretical\ndescription of Raman processes."
    },
    {
        "anchor": "Topological Effect of Surface Plasmon Excitation in Gapped Isotropic\n  Topological Insulator Nanowires: We present a theoretical investigation of the surface plasmon (SP) at the\ninterface between topologically non-trivial cylindrical core and\ntopological-trivial surrounding material, from the axion electrodynamics and\nmodified constitutive relations. We find that the topological effect always\nleads to a red-shift of SP energy, while the energy red-shift decreases\nmonotonically as core diameter decreases. A qualitative picture based on\nclassical perturbation theory is given to explain these phenomena, from which\nwe also infer that in order to enhance the shift, the difference between the\ninverse of dielectric constants of two materials shall be increased. We also\nfind that the surrounding magnetic environment suppresses the topological\neffect. All these features can be well described by a simple ansatz surface\nwave, which is in good agreement with full electromagnetic eigenmodes. In\naddition, bulk plasmon energy at \\omega_{P}=17.5\\pm0.2eV for semiconducting\nBi2Se3 nanoparticle is observed from high-resolution Electron Energy Loss\nSpectrum Image measurements.",
        "positive": "Aharonov-Bohm-Coulomb Problem in Graphene Ring: We study the Aharonov-Bohm-Coulomb problem in a graphene ring. We\ninvestigate, in particular, the effects of a Coulomb type potential of the form\n$\\xi/r$ on the energy spectrum of Dirac electrons in the graphene ring in two\ndifferent ways: one for the scalar coupling and the other for the vector\ncoupling. It is found that, since the potential in the scalar coupling breaks\nthe time-reversal symmetry between the two valleys as well as the effective\ntime-reversal symmetry in a single valley, the energy spectrum of one valley is\nseparated from that of the other valley, demonstrating a valley polarization.\nIn the vector coupling, however, the potential does not break either of the two\nsymmetries and its effect appears only as an additive constant to the spectrum\nof Aharonov-Bohm potential. The corresponding persistent currents, the\nobservable quantities of the symmetry-breaking energy spectra, are shown to be\nasymmetric about zero magnetic flux in the scalar coupling, while symmetric in\nthe vector coupling."
    },
    {
        "anchor": "Symmetry breaking by the sea of Dirac-Landau levels in graphene: The quantum Hall states of graphene have a filled Dirac sea of Landau levels.\nThe short ranged SU(4) symmetry breaking interactions can induce a staggered\npolarization of the sea of Dirac-Landau levels. We study this effect in the\nextended Hubbard model on a honeycomb lattice using mean field variational\nwavefunctions. We find a valley symmetry broken, anti-ferromagnetic spin\nordered phase at $\\nu=\\pm 1$ when the on-site interaction is dominant. Our mean\nfield solution is consistent with the recently reported experimental results of\nZ. Jiang et. al.\\cite{jiang}",
        "positive": "Efficient protocol for qubit initialization with a tunable environment: We propose an efficient qubit initialization protocol based on a dissipative\nenvironment that can be dynamically adjusted. Here the qubit is coupled to a\nthermal bath through a tunable harmonic oscillator. On-demand initialization is\nachieved by sweeping the oscillator rapidly into resonance with the qubit. This\nresonant coupling with the engineered environment induces fast relaxation to\nthe ground state of the system, and a consecutive rapid sweep back to off\nresonance guarantees weak excess dissipation during quantum computations. We\nsolve the corresponding quantum dynamics using a Markovian master equation for\nthe reduced density operator of the qubit-bath system. This allows us to\noptimize the parameters and the initialization protocol for the qubit. Our\nanalytical calculations show that the ground-state occupation of our system is\nwell protected during the fast sweeps of the environmental coupling and,\nconsequently, we obtain an estimate for the duration of our protocol by solving\nthe transition rates between the low-energy eigenstates with the Jacobian\ndiagonalization method. Our results suggest that the current experimental state\nof the art for the initialization speed of superconducting qubits at a given\nfidelity can be considerably improved."
    },
    {
        "anchor": "Ground state of graphene heterostructures in the presence of random\n  charged impurities: We study the effect of long-range disorder created by charge impurities on\nthe carrier density distribution of graphene-based heterostructures. We\nconsider heterostructures formed by two graphenic sheets (either single layer\ngraphene, SLG, or bilayer graphene, BLG) separated by a dielectric film. We\npresent results for symmetric heterostructures, SLG-SLG and BLG-BLG, and hybrid\nones, BLG-SLG. As for isolated layers, we find that the presence of charged\nimpurities induces strong carrier density inhomogeneities, especially at low\ndopings where the density landscape breaks up in electron-hole puddles. We\nprovide quantitative results for the strength of the carrier density\ninhomogeneities and for the screened disorder potential for a large range of\nexperimentally relevant conditions. For heterostructures in which BLG is\npresent we also present results for the band-gap induced by the perpendicular\nelectric field generated self-consistently by the disorder potential and by the\ndistribution of charges in the heterostructure. For SLG-SLG heterostructures we\ndiscuss the relevance of our results for the understanding of the recently\nobserved metal-insulator transition in each of the graphene layers forming the\nheterostructure. Moreover, we calculate the correlation between the density\nprofiles in the two graphenic layers and show that for standard experimental\nconditions the two profiles are well correlated.",
        "positive": "Tunable coupling scheme for flux qubits at the optimal point: We discuss a practical design for tunably coupling a pair of flux qubits via\nthe quantum inductance of a third high-frequency qubit. The design is\nparticularly well suited for realizing a recently proposed microwave-induced\nparametric coupling scheme. This is attractive because the qubits can always\nremain at their optimal points. Furthermore, we will show that the resulting\ncoupling also has an optimal point where it is insensitive to low-frequency\nflux noise. This is an important feature for the coherence of coupled qubits.\nThe presented scheme is an experimentally realistic way of carrying out\ntwo-qubit gates and should be easily extended to multiqubit systems."
    },
    {
        "anchor": "Reply to the Comment on the 'Hole-digging' in ensembles of tunneling\n  molecular magnets: Reply to the Comment of J.J. Alonso and J.F. Fernandez on the paper\n\"'Hole-digging' in ensembles of tunneling molecular magnets\" of I.S. Tupitsyn,\nP.C.E. Stamp and N.V. Prokof'ev (Phys. Rev. B 69, 132406, (2004)).",
        "positive": "Pulsed-gate spectroscopy of single-electron spin states in bilayer\n  graphene quantum dots: Graphene and bilayer graphene quantum dots are promising hosts for spin\nqubits with long coherence times. Although recent technological improvements\nmake it possible to confine single electrons electrostatically in bilayer\ngraphene quantum dots, and their spin and valley texture of the single particle\nspectrum has been studied in detail, their relaxation dynamics remains still\nunexplored. Here, we report on transport through a high-frequency gate\ncontrolled single-electron bilayer graphene quantum dot. By transient current\nspectroscopy of single-electron spin states, we extract a lower bound of the\nspin relaxation time of 0.5~$\\mu$s. This result represents an important step\ntowards the investigation of spin coherence times in graphene-based quantum\ndots and the implementation of spin-qubits."
    },
    {
        "anchor": "Friction of Physisorbed Nanotubes: Rolling or Sliding?: The structure and motion of carbon and h-BN nanotubes (NTs) deposited on\ngraphene is inquired theoretically by simulations based on state-of-the-art\ninteratomic force fields. Results show that any typical cylinder-over-surface\napproximation is essentially inaccurate. NTs tend to flatten at the interface\nwith the substrate and upon driving they can either roll or slide depending on\ntheir size and on their relative orientation with the substrate. In the\nepitaxially aligned orientation we find that rolling is always the main\nmechanism of motion, producing a kinetic friction linearly growing with the\nnumber of walls, in turn causing an unprecedented supra-linear scaling with the\ncontact area. A 30 degrees misalignment raises superlubric effects, making\nsliding favorable against rolling. The resulting rolling-to-sliding transition\nin misaligned NTs is explained in terms of the faceting appearing in large\nmulti-wall tubes, which is responsible for the increased rotational stiffness.\nModifying the geometrical conditions provides an additional means of\ndrastically tailoring the frictional properties in this unique tribological\nsystem.",
        "positive": "High-gradient operators in perturbed Wess-Zumino-Witten field theories\n  in two dimensions: Many classes of non-linear sigma models (NLSMs) are known to contain\ncomposite operators with an arbitrary number 2s of derivatives (\"high-gradient\noperators\") which appear to become strongly relevant within RG calculations at\none (or fixed higher) loop order, when the number 2s of derivatives becomes\nlarge. This occurs at many conventional fixed points of NLSMs which are\nperturbatively accessible within the usual epsilon-expansion in d=2+\\epsilon\ndimensions. Since such operators are not prohibited from occurring in the\naction, they appear to threaten the very existence of such fixed points. At the\nsame time, for NLSMs describing metal-insulator transitions of Anderson\nlocalization in electronic conductors, the strong RG-relevance of these\noperators has been previously related to statistical properties of the\nconductance of samples of large finite size (\"conductance fluctuations\"). In\nthis paper, we analyze this question, not for perturbative RG treatments of\nNLSMs, but for 2d Wess-Zumino-Witten (WZW) models at level k, perturbatively in\nthe current-current interaction of the Noether current. WZW models are special\n(\"Principal Chiral\") NLSMs on a Lie Group G with a WZW term at level k. In\nthese models the role of high-gradient operators is played by homogeneous\npolynomials of order 2s in the Noether currents, whose scaling dimensions we\nanalyze. For the Lie Supergroup G=GL(2N|2N) and k=1, this corresponds to\ntime-reversal invariant problems of Anderson localization in the so-called\nchiral symmetry classes, and the strength of the current-current interaction, a\nmeasure of the strength of disorder, is known to be completely marginal (for\nany k). We find that all high-gradient (polynomial) operators are, to one loop\norder, irrelevant or relevant depending on the sign of that interaction."
    },
    {
        "anchor": "Quantum Entanglement Manifestation of Transition to Nonlinear\n  Self-trapping for Bose-Einstein Condensates in a Symmetric Double-Well: We investigate the nonlinear self-trapping phenomenon of the Bose-Einstein\ncondensates (BEC) in a symmetric double-well, emphasizing on its behind\ndynamical phase transition. With increasing the nonlinear parameter depicting\nthe interaction between the degenerate atoms the BEC turns to be self-trapped\nmanifesting an asymmetric distribution of the atomic density profile. Essence\nof this phenomenon is revealed to be a continuous phase transition and\nunderlying critical behavior is studied analytically and found to follow a\nlogarithm scaling-law. We then go beyond the mean field treatment and extend to\ndiscuss the effect of the many-body quantum fluctuation on the transition. It\nis found that the transition point is shifted and the scaling-law is broken. In\nparticular, the quantum phase transition is accompanied by the change of the\nentanglement entropy which is found to reach maximum at transition point.\nBehind physics is revealed.",
        "positive": "Topological damping Rashba spin orbit torque in ballistic magnetic\n  domain walls: Rashba spin orbit torque derived from the broken inversion symmetry at\nferromagnet/heavy metal interfaces has potential application in spintronic\ndevices. In conventional description of the precessional and damping components\nof the Rashba spin orbit torque in magnetization textures, the decomposition\ncoefficients are assumed to be independent of the topology of the underlying\nstructure. Contrary to this common wisdom, for Schr\\\"{o}dinger electrons\ntrespassing ballistically across a magnetic domain wall, we found that the\ndecomposition coefficient of the damping component is determined by the\ntopology of the domain wall. The resultant damping Rashba spin orbit torque is\nprotected by the topology of the underlying magnetic domain wall and robust\nagainst small deviations from the ideal domain wall profile. Our identification\nof a topological damping Rashba spin orbit torque component in magnetic domain\nwalls will help to understand experiments on current driven domain wall motion\nin ferromagnet/heavy metal systems with broken inversion symmetry and to\nfacilitate its utilization in innovative device designs."
    },
    {
        "anchor": "Three-body correlations and finite-size effects in the Moore--Read\n  states on a sphere: Two- and three-body correlations in partially filled degenerate fermion\nshells are studied numerically for various interactions between the particles.\nThree distinct correlation regimes are defined, depending on the short-range\nbehavior of the pair pseudopotential. For pseudopotentials similar to those of\nelectrons in the first excited Landau level, correlations at half-filling have\na simple three-body form consisting of the maximum avoidance of the triplet\nstate with the smallest relative angular momentum R_3=3. In analogy to the\nsuperharmonic criterion for Laughlin two-body correlations, their occurrence is\nrelated to the form of the three-body pseudopotential at short range. The\nspectra of a model three-body repulsion are calculated, and the zero-energy\nMoore--Read ground state, its +-e/4-charged quasiparticles, and the\nmagnetoroton and pair-breaking bands are all identified. The quasiparticles are\ncorrectly described by a composite fermion model appropriate for Halperin's\np-type pairing with Laughlin correlations between the pairs. However, the\nMoore--Read ground state, and specially its excitations, have small overlaps\nwith the corresponding Coulomb eigenstates when calculated on a sphere. The\nreason lies in surface curvature which affects the form of pair pseudopotential\nfor which the \"R_3>3\" three-body correlations occur. In finite systems, such\npseudopotential must be slightly superharmonic at short range (different from\nCoulomb pseudopotential). However, the connection with the three-body\npseudopotential is less size-dependent, suggesting that the Moore--Read state\nand its excitations are a more accurate description for experimental nu=5/2\nstates than could be expected from previous calculations.",
        "positive": "Measuring cotunneling in its wake: We introduce a rate formalism to treat classically forbidden electron\ntransport through a quantum dot (cotunneling) in the presence of a coupled\nmeasurement device. We demonstrate this formalism for a toy model case of\ncotunneling through a single-level dot while being coupled to a strongly\npinched-off quantum point contact (QPC). We find that the detector generates\nthree types of back-action: the measurement collapses the coherent transport\nthrough the virtual state, but at the same time allows for QPC-assisted\nincoherent transport, and widens the dot level. Last, we obtain the measured\ncotunneling time from the cross correlation between dot and QPC currents."
    },
    {
        "anchor": "A concentric plasmonic platform for the efficient excitation of surface\n  plasmon-polaritons: We propose a plasmonic device consisting of a concentric ring grating acting\nas an efficient tool for directional launching and detection of surface\nplasmon-polaritons (SPPs). Numerical simulations and optical characterizations\nare used to study the fabricated structured gold surface. We demonstrate that\nthis circularly symmetrical plasmonic device provides an efficient interface\nbetween free space radiation and SPPs. This structure offers an excellent\nplatform for the study of hybrid plasmonics in general and of plasmon-emitter\ncouplings in particular, such as those occurring when exciting dye molecules\nplaced inside the ring. As illustrated in this work, an interesting property of\nthe device is that the position of excitation determines the direction of\npropagation of the SPPs, providing a flexible mean of studying their\ninteractions with molecules or dipole-like emitters placed on the surface.",
        "positive": "Signatures of Quantum Coherence in Rydberg Excitons: Coherent optical control of individual particles has been demonstrated both\nfor atoms and semiconductor quantum dots. Here we demonstrate the emergence of\nquantum coherent effects in semiconductor Rydberg excitons in bulk Cu$_2$O. Due\nto the spectral proximity between two adjacent Rydberg exciton states, a\nsingle-frequency laser may pump both resonances with little dissipation from\nthe detuning. As a consequence, additional resonances appear in the absorption\nspectrum that correspond to dressed states consisting of two Rydberg exciton\nlevels coupled to the excitonic vacuum, forming a V-type three-level system,\nbut driven only by one laser light source. We show that the level of pure\ndephasing in this system is extremely low. These observations are a crucial\nstep towards coherently controlled quantum technologies in a bulk\nsemiconductor."
    },
    {
        "anchor": "Hybrid Interference Induced Flat Band Localization in Bipartite\n  Optomechanical Lattices: The flat band localization, as an important phenomenon in solid state\nphysics, is fundamentally interesting in the exploration of exotic ground\nproperty of many-body system. Here we demonstrate the appearance of a flat band\nin a general bipartite optomechanical lattice, which could have one or two\ndimensional framework. Physically, it is induced by the hybrid interference\nbetween the photon and phonon modes in optomechanical lattice, which is quite\ndifferent from the destructive interference resulted from the special geometry\nstructure in the normal lattice (e.g., Lieb lattice). Moreover, this novel flat\nband is controllable and features a special local density of states (LDOS)\npattern, which makes it is detectable in experiments. This work offers an\nalternative approach to control the flat band localization with optomechanical\ninteraction, which may substantially advance the fields of cavity optomechanics\nand solid state physics.",
        "positive": "NMR detection of dynamical processes in antiferroelectric nanoclusters\n  during the order-disorder transition in NH4H2AsO4: We study the dynamics of inorganic antiferroelectric nanoclusters formed\nduring an order-disorder transition and demonstrate the coexistence of the two\nphases in a region of 2-3 K around the transition temperature TN~215 K. Single\ncrystals of NH4H2AsO4, a model hydrogen-bonded compound, show an\nantiferroelectric-paraelectric transition studied by means of highly sensitive\nmagic angle spinning 15N NMR at 21.1 T. The phase co-existence is demonstrated\nby a double-peak structure of the chemical shift. Two-dimensional chemical\nexchange spectroscopy and spin-lattice relaxation time (T1) measurements show\nthat the clusters are dynamic with sizes ~50 nm and lifetimes approaching\nseconds as T->TN. Their occupancy increases rapidly to fill the crystal volume\nbelow $T_N$. This study provides evidence for the commonality of the phase\ntransitions in systems with electric properties and provides an improved\nspectroscopic method for such studies."
    },
    {
        "anchor": "Phase lapses in transmission through interacting two-level quantum dots: We investigate the appearance of pi lapses in the transmission phase theta of\na two-level quantum dot with Coulomb interaction U. Using the numerical and\nfunctional renormalization group methods we study the entire parameter space\nfor spin-polarized as well as spin-degenerate dots, modeled by spinless or\nspinful electrons, respectively. We investigate the effect of finite\ntemperatures T. For small T and sufficiently small single-particle spacings\ndelta of the dot levels we find pi phase lapses between two transmission peaks\nin an overwhelming part of the parameter space of the level-lead couplings. For\nlarge delta the appearance or not of a phase lapse between resonances depends\non the relative sign of the level-lead couplings in analogy to the U=0 case. We\nshow that this generic scenario is the same for spin-polarized and\nspin-degenerate dots. We emphasize that in contrast to dots with more levels,\nfor a two-level dot with small delta and generic dot-lead couplings (that is up\nto cases with special symmetry) the \"universal\" phase lapse behavior is already\nestablished at U=0. The most important effect of the Coulomb interaction is to\nincrease the separation of the transmission resonances. The relation of the\nappearance of phase lapses to the inversion of the population of the dot levels\nis discussed. For the spin-polarized case and low temperatures we compare our\nresults to recent mean-field studies. For small delta correlations are found to\nstrongly alter the mean-field picture.",
        "positive": "Quantum oscillations in 2D insulators induced by graphite gates: We demonstrate a mechanism for magnetoresistance oscillations in insulating\nstates of two-dimensional (2D) materials arising from the interaction of the 2D\nlayer and proximal graphite gates. We study a series of devices based on\ndifferent two-dimensional systems, including mono- and bilayer Td-WTe2,\nangle-aligned MoTe2/WSe2 heterobilayers and Bernal-stacked bilayer graphene,\nwhich all share a similar graphite-gated geometry. We find that the resistivity\nof the 2D system generically shows quantum oscillations as a function of\nmagnetic field corresponding to a high-density Fermi surface when they are\ntuned near an insulating state, in contravention of na\\\"ive band theory.\nSimultaneous measurement of the resistivity of the graphite gates show that\nthese oscillations are precisely correlated with quantum oscillations in the\nresistivity of the graphite gates themselves. Further supporting this\nconnection, the oscillations are quenched when the graphite gate is replaced by\nTaSe2, a high-density metal that does not show quantum oscillations. The\nobserved phenomenon arises from the oscillatory behavior of graphite density of\nstates, which modulates the device capacitance and, as a consequence, the\ncarrier density in the sample layer even when a constant electrochemical\npotential is maintained between the sample and the gate electrode. Oscillations\nare most pronounced near insulating states where the resistivity is strongly\ndensity dependent. Our study suggests a unified mechanism for quantum\noscillations in graphite-gated 2D insulators based on sample-gate coupling."
    },
    {
        "anchor": "Topological charge and spin Hall effects due to skyrmions in canted\n  antiferromagnets: The topological charge Hall effect (TCHE) and the topological spin Hall\neffect (TSHE), arising from ferromagnetic (FM) and antiferromagnetic (AFM)\nskyrmions, respectively; can be elucidated through the emergence of\nspin-dependent Berry gauge fields that affect the adiabatic flow of electrons\nwithin the skyrmion texture. TCHE is absent in systems with parity-time (PT)\nsymmetry, such as collinear AFM systems. In this study, we theoretically study\nTCHE and TSHE in a canted antiferromagnet within the diffusive regime. Spin\ncanting or weak ferromagnetism in canted AFMs that breaks the PT symmetry may\narise from strong homogeneous Dzyaloshinskii-Morya interactions. Using a\nsemiclassical Boltzmann approach, we obtain diffusion equations for the spin\nand charge accumulations in the presence of finite spin-flip and spin-dependent\nmomentum relaxation times. We show that the finite net magnetization, stemming\nfrom spin canting and the subsequent breaking of parity-time symmetry, results\nin the emergence of both finite TCHE and TSHE in AFM systems.",
        "positive": "Building topological device through emerging robust helical surface\n  states: We propose a nonlocal manipulation method to build topological devices\nthrough emerging robust helical surface states in Z_2=0 topological systems.\nSpecifically, in a ribbon of Z_2=0 Bernevig- Hughes-Zhang (BHZ) model with\nfinite-size effect, if magnetic impurities are doped on the top (bottom) edge,\nthe edge states on the bottom (top) edge can be altered according to the\nstrengths and directions of these magnetic impurities. Consequently, the\nbackscattering between the emerging robust helical edge states and gapped\nnormal edge states due to finite-size confinement is also changed, which makes\nthe system alternate between a perfect one-channel conductor and a perfect\ninsulator. This effect allows us to fabricate topological devices with high\non-off ratio. Moreover, it can also be generalized to 3D model and more\nrealistic Cd3As2 type Dirac semimetals."
    },
    {
        "anchor": "Decoherence of Macroscopic States at Finite Temperatures: We study the macroscopic superposition of light coherent states of the type\nSchrodinger cat states; analizying, in particular, the role of the temperature\nin the decoherence processes, characteristic of the superposition of\nmacroscopic states. The method we use here is based on the Master equation\nformalism, introducing an original approach. We use a modified Mandel function\nthat is well adapted to the problem. This work is motivated by the experiments\nproposed by S. Haroche and collaborators in the 90's. In these experiments two\nRydberg atoms were sent to a cavity in which a coherent state had been\npreviously injected, monitoring the decay of quantum states due to dissipation.\nWe find Haroche and collaborator's result at zero temperature and we predict\nthe behavior of the field states in the cavity at finite temperatures.",
        "positive": "Friedel oscillations of the magnetic field penetration in systems with\n  spatial quantization: The magnetic field, applied to a size-quantized system produces equilibrium\npersistent current non-uniformly distributed across the system. The\ndistributions of dia- and paramagnetic currents and magnetic field in a quantum\nwell is found. We discuss the possibility of observation of field distribution\nby means of NMR."
    },
    {
        "anchor": "Valley Depolarization in Monolayer Transition-Metal Dichalcogenides with\n  Zone-Corner Acoustic Phonons: Although single-layer transition-metal dichalcogenides with novel valley\nfunctionalities are promising candidate to realize valleytronic devices, the\nessential understanding of valley depolarization mechanisms is still\nincomplete. Based on pump-probe experiments performed for MoSe2 and WSe2\nmonolayers and corroborating analysis from density functional calculations, we\ndemonstrate that coherent phonons at the K-point of the Brillouin zone can\neffectively mediate the valley transfer of electron carriers. In the MoSe2\nmonolayer case, we identify this mode as the flexural acoustic ZA(K) mode,\nwhich has broken inversion symmetry and thus can enable electron spin-flip\nduring valley transfer. On the other hand, in the monolayer WSe2 case where\nspin-preserving inter-valley relaxations are preferred coherent LA(K) phonons\nwith even inversion symmetry are efficiently generated. These findings\nestablish that, while the specifics of inter-valley relaxations depend on the\nspin alignments of energy bands, the K-point phonons should be taken into\naccount as an effective valley depolarization pathway in transition metal\ndichalcogenide monolayers.",
        "positive": "Brown-Zak and Weiss oscillations in a gate-tunable graphene\n  superlattice: A unified picture of miniband conductivity: Electrons exposed to a two-dimensional (2D) periodic potential and a uniform,\nperpendicular magnetic field exhibit a fractal, self-similiar energy spectrum\nknown as the Hofstadter butterfly. Recently, related high-temperature quantum\noscillations (Brown-Zak oscillations) were discovered in graphene moir\\'{e}\nsystems, whose origin lie in the repetitive occurrence of extended\nminibands/magnetic Bloch states at rational fractions of magnetic flux per unit\ncell giving rise to an increase in band conductivity. In this work, we report\non the experimental observation of band conductivity oscillations in an\nelectrostatically defined and gate-tunable graphene superlattice, which are\ngoverned both by the internal structure of the Hofstadter butterfly (Brown-Zak\noscillations) and by a commensurability relation between the cyclotron radius\nof electrons and the superlattice period (Weiss oscillations). We obtain a\ncomplete, unified description of band conductivity oscillations in\ntwo-dimensional superlattices, yielding a detailed match between theory and\nexperiment."
    },
    {
        "anchor": "The quantum Hall effect in graphene - a theoretical perspective: This short theoretical review deals with some essential ingredients for the\nunderstanding of the quantum Hall effect in graphene in comparison with the\neffect in conventional two-dimensional electron systems with a parabolic band\ndispersion. The main difference between the two systems stems from the\n\"ultra-relativistic\" character of the low-energy carriers in graphene, which\nare described in terms of a Dirac equation, as compared to the non-relativistic\nSchr\\\"odinger equation used for electrons with a parabolic band dispersion. In\nspite of this fundamental difference, the Hall resistance quantisation is\nuniversal in the sense that it is given in terms of the universal constant\nh/e^2 and an integer number, regardless of whether the charge carriers are\ncharacterised by Galilean or Lorentz invariance, for non-relativistic or\nrelativistic carriers, respectively.",
        "positive": "Skyrmion quantum spin Hall effect: The quantum spin Hall effect is conventionally thought to require a strong\nspin-orbit coupling, producing an effective spin-dependent magnetic field.\nHowever, spin currents can also be present without transport of spins, for\nexample, in spin-waves or skyrmions. In this paper, we show that topological\nskyrmionic spin textures can be used to realize a quantum spin Hall effect.\nFrom basic arguments relating to the single-valuedness of the wave function, we\ndeduce that loop integrals of the derivative of the Hamiltonian must have a\nspectrum that is integer multiples of $ 2 \\pi $. By relating this to the spin\ncurrent, we form a new quantity called the quantized spin current which obeys a\nprecise quantization rule. This allows us to derive a quantum spin Hall effect,\nwhich we illustrate with an example of a spin-1 Bose-Einstein condensate."
    },
    {
        "anchor": "Comment on 'Linking Spatial Distributions of Potential and Current in\n  Viscous Electronics': In recent paper of Falkovich and Levitov it was shown, that geometry of\nseparatrixes for viscous electronic flow in graphene is sensitive to boundary\nconditions. Here we discover theis relation in details. Also we propose, how\nboundary conditions could be probed experimentally, using weak magnetic field\nand observed features of separatrixes.",
        "positive": "Field emission: the theoretical link between voltage loss, reduction in\n  field enhancement factor, and Fowler-Nordheim-plot saturation: With a large-area field electron emitter, when an individual post-like\nemitter is sufficiently resistive, and current through it sufficiently large,\nthen voltage loss occurs along it. This Letter provides a simple analytical and\nconceptual demonstration that this voltage loss is directly and inextricably\nlinked to a reduction in the field enhancement factor (FEF) at the post apex. A\nformula relating apex-FEF reduction to this voltage loss was obtained in the\npaper by E. Minoux, O. Groening, K. B. K. Teo, S. H. Dalal, L. Gangloff, J.-P.\nSchnell, L. Hudanski, I. Y. Y. Bu., P. Vincent, P. Legagneux, G. A. J.\nAmaratunga, and W. I. Milne [Nano Lett. 5, 2135 (2005)], by fitting to\nnumerical results from a Laplace solver. This Letter derives the same formula\nanalytically, by using a \"floating sphere\" model. The analytical proof brings\nout the underlying physics more clearly, and shows that the effect is a general\nphenomenon, related to reduction in the magnitude of the surface charge in the\nmost protruding parts of an emitter. Voltage-dependent FEF-reduction is one\ncause of \"saturation\" in Fowler-Nordheim plots. Another is a voltage-divider\neffect, due to measurement-circuit resistance. An integrated theory of both\neffects is presented. Both together, or either by itself, can cause saturation.\nExperimentally, if saturation occurs but voltage loss is small (< 20 V, say),\nthen saturation is more probably due to FEF-reduction than voltage division. In\nthis case, existing treatments of electrostatic interaction (\"shielding\")\nbetween closely spaced emitters may need modification. Other putative causes of\nsaturation exist, so the present theory is a partial story. Its extension seems\npossible, and could lead to a more general physical understanding of the causes\nof FN-plot saturation."
    },
    {
        "anchor": "Enhanced Thermoelectric Performance of Nanostructured Nickel Doped Ag2Te: We report on the thermoelectric properties of nickel doped Ag2-xNixTe (x = 0,\n0.015, 0.025 & 0.055, 0.115, 0.155) nanostructures in the temperature (T) range\nof 5 K to 575 K. The electrical resistivity of Ag2Te nanostructure shows\nmetallic behaviour in 5 K to 300 K initially that evolves into two metal to\ninsulator transitions (MITs) at low and mid-temperature regimes with increasing\nx due to Mott-variable range hopping (VRH) and Arrhenius transports,\nrespectively. Their Seebeck coefficient varies nearly in a linear fashion in\nthis temperature range, showing metallic or doped-degenerate semiconducting\nbehaviour. Notably, this behaviour of the Seebeck coefficient is in contrast to\nMott VRH conduction as observed in resistivity. The steady increase in\nresistivity and S with the sharp decrease in thermal conductivity between 410 K\nto 425 K associated with the structural phase transition accomplishes a maximum\nthermoelectric figure of merit (ZT) of 0.86 near 480 K in x = 0.155. This is\nabout 83 % more compared to that of bulk Ag2Te, and shows a significant\nimprovement over the best value reported for Ag2Te nanostructures thus far.\nThis study, therefore, shows that simultaneous nanocomposite formation, doping\nand nanostructuring could be an effective strategy for tuning the electron and\nphonon transports to improve the thermoelectric properties of a material.",
        "positive": "Band-gap engineering and ballistic transport in corrugated graphene\n  nanoribbons: We calculate the band structure and the conductance of periodic corrugated\ngraphene nanoribbons within the framework of the tight-binding $p$-orbital\nmodel. We consider corrugated structures based on host ribbons with armchair\nand zigzag edges and three different types of corrugations (armchair edges,\nzigzag edges as well as a rectangular corrugation). We demonstrate that for\narmchair host ribbons, depending on the type of corrugation, a band gap or\nlow-velocity minibands appear near the charge neutrality point. For higher\nenergies the allowed Bloch state bands become separated by mini-stopbands. By\ncontrast, for corrugated ribbons with the zigzag host, the corrugations\nintroduce neither band gaps nor stopbands (except for the case of the\nrectangular corrugations). The conductances of finite corrugated ribbons are\nanalyzed on the basis of the corresponding band structures. For a sufficiently\nlarge number of corrugations the conductance follows the number of the\ncorresponding propagating Bloch states and shows pronounced oscillations due to\nthe Fabry-Perot interference within the corrugated segments. Finally we\ndemonstrate that edge disorder strongly affects the conductances of corrugated\nribbons. Our results indicate that observation of miniband formation in\ncorrugated ribbons would require clean, edge-disorder free samples, especially\nfor the case of the armchair host lattice."
    },
    {
        "anchor": "Tunable nano Peltier cooling device from geometric effects using a\n  single graphene nanoribbon: Based on the phenomenon of curvature-induced doping in graphene we propose a\nclass of Peltier cooling devices, produced by geometrical effects, without\ngating. We show how a graphene nanorib- bon laid on an array of curved nano\ncylinders can be used to create a targeted and tunable cooling device. Using\ntwo different approaches, the Nonequlibrium Green's Function (NEGF) method and\nexperimental inputs, we predict that the cooling power of such a device can\napproach the order of kW/cm2, on par with the best known techniques using\nstandard superlattice structures. The struc- ture proposed here helps pave the\nway toward designing graphene electronics which use geometry rather than gating\nto control devices.",
        "positive": "Integral Equation Analysis of Plane Wave Scattering by Coplanar\n  Graphene-Strip Gratings in the THz Range: The plane wave scattering and absorption by finite and infinite gratings of\nfree-space standing infinitely long graphene strips are studied in the THz\nrange. A novel numerical approach, based on graphene surface impedance,\nhyper-singular integral equations, and the Nystrom method, is proposed. This\ntechnique guarantees fast convergence and controlled accuracy of computations.\nReflectance, transmittance, and absorbance are carefully studied as a function\nof graphene and grating parameters, revealing the presence of surface plasmon\nresonances. Specifically, larger graphene relaxation times increases the number\nof resonances in the THz range, leading to higher wave transmittance due to the\nreduced losses; on the other hand an increase of graphene chemical potential\nup-shifts the frequency of plasmon resonances. It is also shown that a\nrelatively low number of graphene strips (>10) are able to reproduce Rayleigh\nanomalies. These features make graphene strips good candidates for many\napplications, including tunable absorbers and frequency selective surfaces."
    },
    {
        "anchor": "Observation of even denominator fractional quantum Hall effect in\n  suspended bilayer graphene: We investigate low-temperature magneto-transport in recently developed,\nhigh-quality multi-terminal suspended bilayer graphene devices, enabling the\nindependent measurement of the longitudinal and transverse resistance. We\nobserve clear signatures of the fractional quantum Hall effect, with different\nstates that are either fully developed, and exhibit a clear plateau in the\ntransverse resistance with a concomitant dip in longitudinal resistance, or\nincipient, and exhibit only a longitudinal resistance minimum. All observed\nstates scale as a function of filling factor nu, as expected. An unprecedented\neven-denominator fractional state is observed at nu = -1/2 on the hole side,\nexhibiting a clear plateau in Rxy quantized at the expected value of 2h/e^2\nwith a precision of ~0.5%. Many of our observations, together with a recent\nelectronic compressibility measurement performed in graphene bilayers on\nhexagonal boron-nitride (hBN) substrates, are consistent with a recent theory\nthat accounts for the effect of the degeneracy between the N=0 and N=1 Landau\nlevels in the fractional quantum Hall effect, and predicts the occurrence of a\nMoore-Read type nu = -1/2 state. Owing to the experimental flexibility of\nbilayer graphene --which has a gate-dependent band structure, can be easily\naccessed by scanning probes, and can be contacted with materials such as\nsuperconductors--, our findings offer new possibilities to explore the\nmicroscopic nature of even-denominator fractional quantum Hall effect.",
        "positive": "Donor hyperfine Stark shift and the role of central-cell corrections in\n  tight-binding theory: Atomistic tight-binding (TB) simulations are performed to calculate the Stark\nshift of the hyperfine coupling for a single Arsenic (As) donor in Silicon\n(Si). The role of the central-cell correction is studied by implementing both\nthe static and the non-static dielectric screenings of the donor potential, and\nby including the effect of the lattice strain close to the donor site. The\ndielectric screening of the donor potential tunes the value of the quadratic\nStark shift parameter ($\\eta_2$) from -1.3 $\\times$ 10$^{-3} \\mu$m$^2$/V$^2$\nfor the static dielectric screening to -1.72 $\\times$ 10$^{-3} \\mu$m$^2$/V$^2$\nfor the non-static dielectric screening. The effect of lattice strain,\nimplemented by a 3.2% change in the As-Si nearest-neighbour bond length,\nfurther shifts the value of $\\eta_2$ to -1.87 $\\times$ 10$^{-3}\n\\mu$m$^2$/V$^2$, resulting in an excellent agreement of theory with the\nexperimentally measured value of -1.9 $\\pm$ 0.2 $\\times$ 10$^{-3}\n\\mu$m$^2$/V$^2$. Based on our direct comparison of the calculations with the\nexperiment, we conclude that the previously ignored non-static dielectric\nscreening of the donor potential and the lattice strain significantly influence\nthe donor wave function charge density and thereby leads to a better agreement\nwith the available experimental data sets."
    },
    {
        "anchor": "Giant intrinsic photoresponse in pristine graphene: When the Fermi level matches the Dirac point in graphene, the reduced charge\nscreening can dramatically enhance electron-electron (e-e) scattering to\nproduce a strongly interacting Dirac liquid. While the dominance of e-e\nscattering already leads to novel behaviors, such as electron hydrodynamic\nflow, further exotic phenomena have been predicted to arise specifically from\nthe unique kinematics of e-e scattering in massless Dirac systems. Here, we use\noptoelectronic probes, which are highly sensitive to the kinematics of electron\nscattering, to uncover a giant intrinsic photocurrent response in pristine\ngraphene. This photocurrent emerges exclusively at the charge neutrality point\nand vanishes abruptly at non-zero charge densities. Moreover, it is observed at\nplaces with broken reflection symmetry, and it is selectively enhanced at free\ngraphene edges with sharp bends. Our findings reveal that the photocurrent\nrelaxation is strongly suppressed by a drastic change of fast photocarrier\nkinematics in graphene when its Fermi level matches the Dirac point. The\nemergence of robust photocurrents in neutral Dirac materials promises new\nenergy-harvesting functionalities and highlights intriguing electron dynamics\nin the optoelectronic response of Dirac fluids.",
        "positive": "Reverse Monte Carlo reconstruction of electron spin-label coordinates\n  from scanned-probe magnetic resonance microscope signals: Individual electron spins have been observed using magnetic resonance in\ncombination with a number of distinct detection approaches. The coordinates of\nan individual electron spin can then in principle be determined by introducing\na 10 to 100 nm diameter magnetic needle, scanning the needle, and collecting\nsignal as a function of the needle's position. Although individual electrons\nhave recently been localized with nanometer precision in this way using a\nnitrogen-vacancy center in diamond as the spin detector, the experiment's low\nsignal-to-noise ratio limited acquisition to two-dimensional scanning of just a\nfew dozen data points and was incompatible with nitroxide spin labels widely\nused to label proteins and nucleic acids. We introduce and numerically simulate\na protocol for detecting and imaging individual nitroxide electron spins\nmechanically with high spatial resolution. In our protocol a scanned\nmagnet-tipped cantilever is brought near the sample, modulated microwaves are\napplied to resonantly excite electron spins, and changes in spin magnetization\nare detected as a shift in the mechanical frequency of the cantilever. By\ncarefully applying resonant microwaves in short bursts in synchrony with the\ncantilever's oscillation, we propose to retain high spatial resolution even at\nlarge cantilever amplitude where sensitivity is highest. Numerical simulations\nreveal nanometer-diameter rings of frequency-shift signal as the tip is\nscanned. Our primary finding is that it is possible --- using a Bayesian,\nreverse Monte Carlo algorithm introduced here --- to obtain the full\nthree-dimensional distribution of electron coordinates from the signal rings\nrevealed in a two-dimensional frequency-shift map. This reduction in\ndimensionality brings within reach, on a practical timescale, the\nangstrom-resolution three-dimensional imaging of spin-labeled macromolecules."
    },
    {
        "anchor": "Mach-Zehnder Interferometric device for spin filtering in a GaAs/AlGaAs\n  electron gas: A spin filtering device using quantum spin interference is theoretically\nproposed in a GaAs/AlGaAs electron gas that has both Rashba and Dresselhaus\nspin-orbit couplings. The device achieves polarized electron currents by\nseparating spin up and spin down components without a magnetic field gradient.\nWe find two broad spin filtering regimes, one where the interferometer has\nsymmetrical arms, where a small magnetic flux is needed to achieve spin\nseparation, and the other with asymmetric arms where the change in path length\nrenders an extra phase emulating the effects of a magnetic field. We identify\noperating points for the device where optimal electron polarization is achieved\nwithin value ranges found in a 2D electron gas. Both device setups apply for\narbitrary incoming electron polarization and operate at broad energy ranges\nwithin the incoming electron band.",
        "positive": "Adjustable propagating plasmons in $\u03b1-\\mathcal{T}_3$ lattice-based\n  armchair nanoribbons: We have obtained and analyzed the electronic states, polarization function\nand the plasmon excitations for $\\alpha - \\mathcal{T}_3$-based nanoribbons with\narmchair termination. The calculated plasmon dispersions strongly depend on the\nnumber of the atomic rows across the ribbon, and the presence of the energy gap\nbetween the valence and conduction bands which is also determined by the\nnanoribbon geometry. The bandgap was proven to have the strongest effect on\nboth the plasmon dispersions and their Landau damping. We have also\ndemonstrated that for a small electron doping the plasmon dispersions do not\ndepend on the relative hopping parameter $\\alpha$ of the considered $\\alpha -\n\\mathcal{T}_3$ material in the long-wave limit and investigated the conditions\nwhen $\\alpha$ becomes an important factor which strongly affects the plasmons.\nWe believe that our new uncovered electronic and collective properties of\nnano-size $\\alpha - \\mathcal{T}_3$ribbons will find their applications in the\nfield of modern electronics and nanodevices."
    },
    {
        "anchor": "Nonlinear valley and spin currents from Fermi pocket anisotropy in 2D\n  crystals: Controlled flow of spin and valley pseudospin is key to future electronics\nexploiting these internal degrees of freedom of carriers. Here we discover a\nuniversal possibility for generating spin and valley currents by electric bias\nor temperature gradient only, which arises from the anisotropy of Fermi pockets\nin crystalline solids. We find spin and valley currents to the second order in\nthe electric field, as well as their thermoelectric counterparts, i.e. the\nnonlinear spin and valley Seebeck effects. These second-order nonlinear\nresponses allow two unprecedented possibilities to generate pure spin and\nvalley flows without net charge current: (i) by an AC bias; or (ii) by an\narbitrary inhomogeneous temperature distribution. As examples, we predict\nappreciable nonlinear spin and valley currents in two-dimensional (2D) crystals\nincluding graphene, monolayer and trilayer transition metal dichalcogenides,\nand monolayer gallium selenide. Our finding points to a new route towards\nelectrical and thermal generations of spin and valley currents for spintronic\nand valleytronic applications based on 2D quantum materials.",
        "positive": "Quantized Faraday and Kerr rotation and axion electrodynamics of a 3D\n  topological insulator: Topological insulators have been proposed to be best characterized as bulk\nmagnetoelectric materials that show response functions quantized in terms of\nfundamental physical constants. Here we lower the chemical potential of\nthree-dimensional (3D) Bi$_2$Se$_3$ films to $\\sim$ 30 meV above the Dirac\npoint, and probe their low-energy electrodynamic response in the presence of\nmagnetic fields with high-precision time-domain terahertz polarimetry. For\nfields higher than 5 T, we observed quantized Faraday and Kerr rotations,\nwhereas the DC transport is still semi-classical. A non-trivial Berry phase\noffset to these values gives evidence for axion electrodynamics and the\ntopological magnetoelectric effect. The time structure used in these\nmeasurements allows a direct measure of the fine structure constant based on a\ntopological invariant of a solid-state system."
    },
    {
        "anchor": "Terahertz Bloch oscillator with a modulated bias: Electrons performing Bloch oscillations in an energy band of a dc-biased\nsuperlattice in the presence of weak dissipation can potentially generate THz\nfields at room temperature. The realization of such Bloch oscillator is a\nlong-standing problem due to the instability of a homogeneous electric field in\nconditions of negative differential conductivity. We establish the theoretical\nfeasibility of stable THz gain in a long superlattice device in which the bias\nis quasistatically modulated by microwave fields. The modulation waveforms must\nhave at least two harmonics in their spectra.",
        "positive": "Topological Kinetic Crossover in a Nanomagnet Array: Ergodic kinetics, which are critical to equilibrium thermodynamics, can be\nconstrained by a system's topology. We study a model nanomagnetic array in\nwhich such constraints visibly affect the behavior. In this system, magnetic\nexcitations connect into thermally active one-dimensional strings whose motion\ncan be imaged in real time. At high temperatures, we observe the merging,\nbreaking, and reconnecting of strings, resulting in the system transitioning\nbetween topologically distinct configurations. Below a crossover temperature,\nthe string motion is dominated by simple changes in length and shape. In this\nlow temperature regime, the system is energetically stable because of its\ninability to explore all possible topological configurations. This kinetic\ncrossover suggests a generalizable conception of topologically broken\nergodicity and limited equilibration."
    },
    {
        "anchor": "Excitonic thermalization bottleneck in twisted TMD heterostructures: Twisted van der Waals heterostructures show an intriguing interface exciton\nphysics including hybridization effects and emergence of moir\\'e potentials.\nRecent experiments have revealed that moir\\'e-trapped excitons exhibit a\nremarkable dynamics, where excited states show lifetimes that are several\norders of magnitude longer than those in monolayers. The origin of this\nbehaviour is still under debate. Based on a microscopic many-particle approach,\nwe investigate the phonon-driven relaxation cascade of non-equilibrium moir\\'e\nexcitons in the exemplary MoSe$_2$-WSe$_2$ heterostructure. We track the\nexciton relaxation pathway across different moir\\'e mini-bands and identify the\nphonon-scattering channels assisting the spatial redistribution of excitons\ninto low-energy pockets of the moir\\'e potential. We unravel a phonon\nbottleneck in the flat band structure at low twist angles preventing excitons\nto fully thermalize into the lowest state explaining the measured enhanced\nemission intensity of excited moir\\'e excitons. Overall, our work provides\nimportant insights into exciton relaxation dynamics in flatband exciton\nmaterials.",
        "positive": "Energy transfer in strained graphene assisted by discrete breathers\n  excited by external ac driving: In the present molecular dynamics study, external ac driving is used at\nfrequencies outside the phonon spectrum to excite gap DBs in uniformly strained\ngraphene nanoribbon. Harmonic displacement or harmonic force is applied to a\nzigzag atomic chain of graphene. In the former case non-propagating DBs are\nexcited on the atoms next to the driven atoms, while in the latter case the\nexcited DBs propagate along the nanoribbon. The energy transfer along the\nnanoribbon assisted by the DBs is investigated in detail and the differences\nbetween harmonic displacement driving and harmonic force driving are discussed.\nIt is concluded that the amplitude of external driving at out of phonon\nspectrum frequencies should not necessarily be large to obtain a noticeable\nenergy transfer to the system. Overall, our results suggest that external\nharmonic driving even at relatively small driving amplitudes can be used to\ncontrol excitation of DBs and consequently the energy transfer to the system."
    },
    {
        "anchor": "Disentangling spin, anomalous and planar Hall effects in\n  ferromagnetic/heavy metal nanostructures: Ferromagnetic (FM)/heavy metal (HM) nanostructures can be used for the\nmagnetic state readout in the proposed magneto-electric spin-orbit logic by\nlocally injecting a spin-polarized current and measure the spin-to-charge\nconversion via the spin Hall effect. However, this local configuration is prone\nto spurious signals. In this work, we address spurious Hall effects that can\ncontaminate the spin Hall signal in these FM/HM T-shaped nanostructures. The\nmost pronounced Hall effects in our Co50Fe50/Pt nanostructures are the planar\nHall effect and the anomalous Hall effect generated in the FM nanowire. We find\nthat the planar Hall effect, induced by misalignment between magnetization and\ncurrent direction in the FM wire, is manifested as a shift in the measured\nbaseline resistance, but does not alter the spin Hall signal. In contrast, the\nanomalous Hall effect, arising from the charge current distribution within the\nFM, adds to the spin Hall signal. However, the effect can be made insignificant\nby minimizing the shunting effect via proper design of the device. We conclude\nthat local spin injection in FM/HM nanostructures is a suitable tool for\nmeasuring spin Hall signals and, therefore, a valid method for magnetic state\nreadout in prospective spin-based logic.",
        "positive": "Quantitative analytical theory for disordered nodal points [Article and\n  Erratum]: Disorder effects are especially pronounced around nodal points in linearly\ndispersing bandstructures as present in graphene or Weyl semimetals. Despite\nthe enormous experimental and numerical progress, even a simple quantity like\nthe average density of states cannot be assessed quantitatively by analytical\nmeans. We demonstrate how this important problem can be solved employing the\nfunctional renormalization group method and, for the two dimensional case,\ndemonstrate excellent agreement with reference data from numerical simulations\nbased on tight-binding models. In three dimensions our analytic results also\nimprove drastically on existing approaches."
    },
    {
        "anchor": "Improving reproducibility of quantum devices with completely undoped\n  architectures: The reproducible operation of quantum electronic devices is a key requirement\nfor future quantum information processing and spintronics applications.\nTraditionally quantum devices have been fabricated from modulation doped\nheterostructures, where there is an intrinsic lack of reproducibility due to\nthe random potential from ionized donors. Here we show that we can greatly\nimprove reproducibility over modulation doped devices by using a completely\nundoped architecture, with superior uniformity in the confinement potential and\nmore consistent operating voltages for both electron and hole devices. Our\nresults demonstrate that undoped heterostructures have significant advantages\nover modulation doping for reproducible manufacturing of quantum devices.",
        "positive": "Conductance distribution between Hall plateaus: Mesoscopic fluctuations of two-port conductance and four-port resistance\nbetween Hall plateaus are studied within a realistic model for a\ntwo-dimensional electron gas in a perpendicular magnetic field and a smooth\ndisordered potential. The two-port conductance distribution $P(g)$ is concave\nbetween $g=0$ and $g=1$ and is nearly flat between $g=0.2$ and $g=0.8$. These\ncharacteristics are consistent with recent observations. The distribution is\nfound to be sharply peaked near the end-points $g=0$ and $g=1$. The\ndistribution functions for the three independent resistances in a four-port\nHall bar geometry are, on the other hand, characterized by a central peak and a\nrelatively large width."
    },
    {
        "anchor": "Via Method for Lithography Free Contact and Preservation of 2D Materials: Atomically thin 2D materials span the common components of electronic\ncircuits as metals, semi-conductors, and insulators, and can manifest\ncorrelated phases such as superconductivity, charge density waves, and\nmagnetism. An ongoing challenge in the field is to incorporate these 2D\nmaterials into multi-layer hetero-structures with robust electrical contacts\nwhile preventing disorder and degradation. In particular, preserving and\nstudying air-sensitive 2D materials has presented a significant challenge since\nthey readily oxidize under atmospheric conditions. We report a new technique\nfor contacting 2D materials, in which metal via contacts are integrated into\nflakes of insulating hexagonal boron nitride, and then placed onto the desired\nconducting 2D layer, avoiding direct lithographic patterning onto the 2D\nconductor. The metal contacts are planar with the bottom surface of the boron\nnitride and form robust contacts to multiple 2D materials. These structures\nprotect air-sensitive 2D materials for months with no degradation in\nperformance. This via contact technique will provide the capability to produce\natomic printed circuit boards that can form the basis of more complex\nmulti-layer heterostructures.",
        "positive": "Electronic and optical properties of carbon nanodisks and nanocones: A theoretical study of the electronic properties of nanodisks and nanocones\nis presented within the framework of a tight-binding scheme. The electronic\ndensities of states and absorption coefficients are calculated for such\nstructures with different sizes and topologies. A discrete position\napproximation is used to describe the electronic states taking into account the\neffect of the overlap integral to first order. For small finite systems, both\ntotal and local densities of states depend sensitively on the number of atoms\nand characteristic geometry of the structures. Results for the local densities\nof charge reveal a finite charge distribution around some atoms at the apices\nand borders of the cone structures. For structures with more than 5000 atoms,\nthe contribution to the total density of states near the Fermi level\nessentially comes from states localized at the edges. For other energies the\naverage density of states exhibits similar features to the case of a graphene\nlattice. Results for the absorption spectra of nanocones show a peculiar\ndependence on the photon polarization in the infrared range for all\ninvestigated structures."
    },
    {
        "anchor": "Massless Dirac fermions in two dimensions: Confinement in nonuniform\n  magnetic fields: We show how it is possible to trap two-dimensional massless Dirac fermions in\nspatially inhomogeneous magnetic fields, as long as the formed magnetic quantum\ndot (or ring) is of a slowly decaying nature. It is found that a modulation of\nthe depth of the magnetic quantum dot leads to successive\nconfinement-deconfinement transitions of vortexlike states with a certain\nangular momentum, until a regime is reached where only states with one sign of\nangular momentum are supported. We illustrate these characteristics with both\nexact solutions and a hitherto unknown quasi-exactly solvable model utilizing\nconfluent Heun functions.",
        "positive": "Calculating interface transport parameters at finite temperatures:\n  Nonmagnetic interfaces: First-principles scattering calculations are used to investigate spin\ntransport through interfaces between diffusive nonmagnetic metals where the\nsymmetry lowering leads to an enhancement of the effect of spin-orbit coupling\n(SOC) and to a discontinuity of the spin currents passing through the\ninterfaces. From the conductance and local spin currents calculated for\nnonmagnetic bilayers, we extract values of the room temperature interface\nresistance $R_{\\rm I}$, of the spin memory loss parameter $\\delta$ and of the\ninterface spin Hall angle $\\Theta_{\\rm I}$ for nonmagnetic Au$|$Pt and Au$|$Pd\ninterfaces using a frozen thermal disorder scheme to model finite temperatures.\nSubstantial values of all three parameters are found with important\nconsequences for experiments involving nonmagnetic spacer and capping layers.\nThe temperature dependence of the interface parameters is determined for\nAu$|$Pt."
    },
    {
        "anchor": "Microwave-free magnetometry with nitrogen-vacancy centers in diamond: We use magnetic-field-dependent features in the photoluminescence of\nnegatively charged nitrogen-vacancy centers to measure magnetic fields without\nthe use of microwaves. In particular, we present a magnetometer based on the\nlevel anti-crossing in the triplet ground state at 102.4 mT with a demonstrated\nnoise floor of 6 nT/$\\sqrt{\\text{Hz}}$, limited by the intensity noise of the\nlaser and the performance of the background-field power supply. The technique\npresented here can be useful in applications where the sensor is placed closed\nto conductive materials, e.g. magnetic induction tomography or magnetic field\nmapping, and in remote-sensing applications since principally no electrical\naccess is needed.",
        "positive": "Optical dressing of the electronic response of two-dimensional\n  semiconductors in quantum and classical descriptions of cavity\n  electrodynamics: We study quantum effects of the vacuum light-matter interaction in materials\nembedded in optical cavities. We focus on the electronic response of a\ntwo-dimensional semiconductor placed inside a planar cavity. By using a\ndiagrammatic expansion of the electron-photon interaction, we describe\nsignatures of light-matter hybridization characterized by large asymmetric\nshifts of the spectral weight at resonant frequencies. We follow the evolution\nof the light-dressing from the cavity to the free-space limit. In the cavity\nlimit, light-matter hybridization results in a modification of the optical gap\nwith sizeable spectral weight appearing below the bare gap edge. In the limit\nof large cavities, we find a residual redistribution of spectral weight which\nbecomes independent of the distance between the two mirrors. We show that the\nphoton dressing of the electronic response can be fully explained by using a\nclassical description of light. The classical description is found to hold up\nto a strong coupling regime of the light-matter interaction highlighted by the\nlarge modification of the photon spectra with respect to the empty cavity. We\nshow that, despite the strong coupling, quantum corrections are negligibly\nsmall and weakly dependent on the cavity confinement. As a consequence, in\ncontrast to the optical gap, the single particle electronic band gap is not\nsensibly modified by the strong-coupling. Our results show that quantum\ncorrections are dominated by off-resonant photon modes at high energy. As such,\ncavity confinement can hardly be seen as a knob to control the quantum effects\nof the light-matter interaction in vacuum."
    },
    {
        "anchor": "Potassium-intercalated bulk HfS$_2$ and HfSe$_2$: Phase stability,\n  structure, and electronic structure: We have studied potassium-intercalated bulk HfS$_2$ and HfSe$_2$ by combining\ntransmission electron energy loss spectroscopy, angle-resolved photoemission\nspectroscopy and density functional theory calculations. Calculations of the\nformation energies and the evolution of the energies of the charge carrier\nplasmons as a function of the potassium content show that certain, low\npotassium concentrations $x$ are thermodynamically unstable. This leads to the\ncoexistence of undoped and doped domains if the provided amount of the alkali\nmetal is insufficient to saturate the whole crystal with the minimum\nthermodynamically stable potassium stoichiometry. Beyond this threshold\nconcentration the domains disappear, while the alkali metal and charge carrier\nconcentrations increase continuously upon further addition of potassium. At low\nintercalation levels, electron diffraction patterns indicate a significant\ndegree of disorder in the crystal structure. The initial order in the\nout-of-plane direction is restored at high $x$ while the crystal layer\nthicknesses expand by 33-36%. Superstructures emerge parallel to the planes\nwhich we attribute to the distribution of the alkali metal rather than\nstructural changes of the host materials. The in-plane lattice parameters\nchange by not more than 1%. The introduction of potassium causes the formation\nof charge carrier plasmons. The observation of this semiconductor-to-metal\ntransition is supported by calculations of the density of states (DOS) and band\nstructures as well as angle-resolved photoemission spectroscopy. The calculated\nDOS hint at the presence of an almost ideal two-dimensional electron gas at the\nFermi level for $x<0.6$. The plasmons exhibit quadratic momentum dispersions\nwhich is in agreement with the behavior expected for an ideal electron gas.",
        "positive": "Theory of Activated Transport in Bilayer Quantum Hall Systems: We analyze the transport properties of bilayer quantum Hall systems at total\nfilling factor $\\nu=1$ in drag geometries as a function of interlayer bias, in\nthe limit where the disorder is sufficiently strong to unbind meron-antimeron\npairs, the charged topological defects of the system. We compute the typical\nenergy barrier for these objects to cross incompressible regions within the\ndisordered system using a Hartree-Fock approach, and show how this leads to\nmultiple activation energies when the system is biased. We then demonstrate\nusing a bosonic Chern-Simons theory that in drag geometries, current in a\nsingle layer directly leads to forces on only two of the four types of merons,\ninducing dissipation only in the drive layer. Dissipation in the drag layer\nresults from interactions among the merons, resulting in very different\ntemperature dependences for the drag and drive layers, in qualitative agreement\nwith experiment."
    },
    {
        "anchor": "Relaxation dynamics of the electron distribution in the Coulomb blockade\n  problem: We study the relaxation dynamics of electron distribution function on the\nisland of a single electron transistor. We focus on the 'interaction without\ncoherence regime in which an electron coherence can be neglected but quantum\nfluctuations of charge are strong due to Coulomb interaction. The quantum\nkinetic equation governing the evolution of the electron distribution function\ndue to escape of electrons to the reservoirs is derived. Analytical solutions\nfor time-dependence of the electron distribution are obtained in the regimes of\nweak and strong Coulomb blockade. We find that usual exponential in time\nrelaxation is strongly modified due to the presence of Coulomb interaction.",
        "positive": "Electric polarization in magnetic topological nodal semimetal thin films: We theoretically study the electric polarization in magnetic topological\nnodal semimetal thin films. In magnetically doped topological insulators,\ntopological nodal semimetal phases emerge once the exchange coupling overcomes\nthe band gap. Changing the magnetization direction, nodal structure is\nmodulated and the system becomes topological nodal point or line semimetals. We\nfind that nodal line semimetals are characterized by non-linear electric\npolarization, which is not observed in nodal point semimetals. The non-linear\nresponse originates from the existence of the surface states. Screening effect\nis self consistently included within a mean field approximation and the\nnon-linear electric polarization is observed even in the presence of screening\neffect."
    },
    {
        "anchor": "Proximity-induced Josephson $\u03c0$-Junctions in Topological Insulators: We study two microscopic models of topological insulators in contact with an\n$s$-wave superconductor. In the first model the superconductor and the\ntopological insulator are tunnel coupled via a layer of scalar and of randomly\noriented spin impurities. Here, we require that spin-flip tunneling dominates\nover spin-conserving one. In the second model the tunnel coupling is realized\nby an array of single-level quantum dots with randomly oriented spins. It is\nshown that the tunnel region forms a $\\pi$-junction where the effective order\nparameter changes sign. Interestingly, due to the random spin orientation the\neffective descriptions of both models exhibit time-reversal symmetry. We then\ndiscuss how the proposed $\\pi$-junctions support topological superconductivity\nwithout magnetic fields and can be used to generate and manipulate Kramers\npairs of Majorana fermions by gates.",
        "positive": "Swapping Exchange and Spin-Orbit Coupling in 2D van der Waals\n  Heterostructures: The concept of swapping the two most important spin interactions -- exchange\nand spin-orbit coupling -- is proposed based on two-dimensional multilayer van\nder Waals heterostructures. Specifically, we show by performing realistic ab\ninitio simulations, that a single device consisting of a bilayer graphene\nsandwiched by a 2D ferromagnet Cr$_2$Ge$_2$Te$_6$ (CGT) and a monolayer WS$_2$,\nis able not only to generate, but also to swap the two interactions. The highly\nefficient swapping is enabled by the interplay of gate-dependent layer\npolarization in bilayer graphene and short-range spin-orbit and exchange\nproximity effects affecting only the layers in contact with the sandwiching\nmaterials. We call these structures ex-so-tic, for supplying either exchange\n(ex) or spin-orbit (so) coupling in a single device, by gating. Such\nbifunctional devices demonstrate the potential of van der Waals spintronics\nengineering using 2D crystal multilayers."
    },
    {
        "anchor": "Reentrant topological phase transitions in a disordered spinless\n  superconducting wire: In a one-dimensional spinless p-wave superconductor with coherence length\n\\xi, disorder induces a phase transition between a topologically nontrivial\nphase and a trivial insulating phase at the critical mean free path l=\\xi/2.\nHere, we show that a multichannel spinless p-wave superconductor goes through\nan alternation of topologically trivial and nontrivial phases upon increasing\nthe disorder strength, the number of phase transitions being equal to the\nchannel number N. The last phase transition, from a nontrivial phase into the\ntrivial phase, takes place at a mean free path l = \\xi/(N+1), parametrically\nsmaller than the critical mean free path in one dimension. Our result is valid\nin the limit that the wire width W is much smaller than the superconducting\ncoherence length \\xi.",
        "positive": "Orbital caloritronic transport in strongly interacting quantum dots: We discuss out-of-equilibrium population imbalances between different orbital\nstates due to applied thermal gradients. This purely thermoelectric orbital\neffect appears quite generically in nanostructures with a pseudospin degree of\nfreedom. We establish an orbital Seebeck coefficient that characterizes the\ninduced orbital bias in response to a temperature difference between reservoirs\ncoupled to a quantum conductor. We analyze a two-terminal strongly interacting\nquantum dot with two orbital states and find that the orbital thermopower acts\nas an excellent tool to describe the transition between SU(4) and SU(2) Kondo\nphysics. Our conclusions are reinforced from a detailed comparison with the\ncharge thermopower using numerical renormalization group calculations."
    },
    {
        "anchor": "Noise suppression using symmetric exchange gates in spin qubits: We demonstrate a substantial improvement in the spin-exchange gate using\nsymmetric control instead of conventional detuning in GaAs spin qubits, up to a\nfactor-of-six increase in the quality factor of the gate. For symmetric\noperation, nanosecond voltage pulses are applied to the barrier that controls\nthe interdot potential between quantum dots, modulating the exchange\ninteraction while maintaining symmetry between the dots. Excellent agreement is\nfound with a model that separately includes electrical and nuclear noise\nsources for both detuning and symmetric gating schemes. Unlike exchange control\nvia detuning, the decoherence of symmetric exchange rotations is dominated by\nrotation-axis fluctuations due to nuclear field noise rather than direct\nexchange noise.",
        "positive": "Automated Characterization of a Double Quantum Dot using the Hubbard\n  Model: Semiconductor quantum dots are favorable candidates for quantum information\nprocessing due to their long coherence time and potential scalability. However,\nthe calibration and characterization of interconnected quantum dot arrays have\nproven to be challenging tasks. One method to characterize the configuration of\nsuch an array involves using the Hubbard model. In this paper, we present an\nautomated characterization algorithm that efficiently extracts the Hubbard\nmodel parameters, including tunnel coupling and capacitive coupling energy,\nfrom experimental stability diagrams. Leveraging the dual annealing optimizer,\nwe determine the set of Hubbard parameters that best characterize the\nexperimental data. We compare our method with an alternate, well-established\nmeasure of the tunnel coupling and find good agreement within the investigated\nregime. Our extracted tunnel couplings range from 69 to 517 $\\mu$eV, and we\ndiscuss the limiting factors of our method."
    },
    {
        "anchor": "Exchange interactions from a nonorthogonal basis set: from bulk\n  ferromagnets to the magnetism in low-dimensional graphene systems: We present a computational method to determine the exchange constants in\nisotropic spin models. The method uses the Hamiltonian and overlap matrices\ncomputed from density functional schemes that are based on nonorthogonal basis\nsets. We demonstrate that the new method as implemented in the SIESTA code\nreproduces the Heisenberg interactions of simple metallic bulk ferromagnets as\nobtained from former well--established computational approaches. Then we\naddress $sp$ magnetism in graphene nanostructures. For fluorinated graphene we\nobtain exchange interactions in fairly good agreement with previous\ncalculations using maximally localized Wannier functions and we confirm the\ntheoretical prediction of a 120$^\\circ$ N\\'eel state. Associated with the\nmagnetic edge-states of a zigzag graphene nanoribbon we find rapidly decaying\nexchange interactions, however, with an unconventional distance dependence of\n$\\exp(-\\sqrt{r/\\delta})$. We show that the stiffness constant derived from the\nexchange interactions is consistent with previous estimate based on total\nenergy differences of twisted spin configurations. We highlight that our method\nis an efficient tool for the analysis of novel hybrid nano-structures where\nmetallic and organic components are integrated to form exotic magnetic\npatterns.",
        "positive": "Diminished Short Channel Effects in Nanoscale Double-Gate\n  Silicon-On-Insulator Metal-Oxide- Semiconductor Field-Effect-Transistors due\n  to Induced Back-Gate Step Potential: In this letter we discuss how the short channel behavior in sub 100 nm\nchannel range can be improved by inducing a step surface potential profile at\nthe back gate of an asymmetrical double gate (DG) Silicon-On-Insulator (SOI)\nMetal-Oxide-Semiconductor Field-Effect- Transistor (MOSFET) in which the front\ngate consists of two materials with different work functions."
    },
    {
        "anchor": "Quantum transport in chaotic cavities with tunnel barriers: We bring together the semiclassical approximation, matrix integrals and the\ntheory of symmetric polynomials in order to solve a long standing problem in\nthe field of quantum chaos: to compute transport moments when tunnel barriers\nare present and the number of open channels, $M$, is small. In contrast to\nprevious approaches, ours is non-perturbative in $M$; instead, we arrive at an\nexplicit expression in the form of a power series in the barrier's\nreflectivity, whose coefficients are rational functions of $M$. For general\nmoments we must require that the barriers are equal and time reversal symmetry\nis broken, but for conductance we treat the general situation. Our method\naccounts for exponentially small non-perturbative terms that were not\naccessible to previous semiclassical approaches. We also show how to include\nmore than two leads in the system.",
        "positive": "Mott insulator tuning via structural distortion in monolayer 1T-NbSe2: Mott state in 1T-TaS2 is predicted to host quantum spin liquids (QSL).\nHowever, its insulating mechanism is controversial due to complications from\ninterlayer coupling. Here, we study the Mott state in monolayer 1T-NbSe2, an\nelectronic analogy to TaS2 exempt from interlayer coupling, using spectroscopic\nimaging scanning tunneling microscopy and first principles calculations.\nMonolayer NbSe2 surprisingly displays two types of Star-of-David (SD) motifs\nwith different Mott gap sizes, that are interconvertible via temperature\nvariation. And, bilayer 1T-NbSe2 shows Mott collapse by interlayer coupling.\nOur calculation unveils the two types of SDs possess distinct structural\ndistortions, altering the effective Coulomb energies of the central Nb orbital.\nOur calculation suggests the Mott gap, the same parameter for determining the\nQSL regime, is tunable with strain. This finding offers a general strategy for\nmanipulating the Mott state in 1T-NbSe2 and related systems via structural\ndistortions, which may be tuned into the potential QSL regime."
    },
    {
        "anchor": "\"Wormhole\" geometry for entrapping topologically-protected qubits in\n  non-Abelian quantum Hall states and probing them with voltage and noise\n  measurements: We study a tunneling geometry defined by a single point-contact constriction\nthat brings to close vicinity two points sitting at the same edge of a quantum\nHall liquid, shortening the trip between the otherwise spatially separated\npoints along the normal chiral edge path. This ``wormhole''-like geometry\nallows for entrapping bulk quasiparticles between the edge path and the tunnel\njunction, possibly realizing a topologically protected qubit if the\nquasiparticles have non-Abelian statistics. We show how either noise or simpler\nvoltage measurements along the edge can probe the non-Abelian nature of the\ntrapped quasiparticles.",
        "positive": "Adiabatically twisting a magnetic molecule to generate pure spin\n  currents in graphene: The spin orbit effect in graphene is too muted to have any observable\nsignificance with respect to its application in spintronics. However, graphene\ntechnology is too valuable to be rendered impotent to spin transport. In this\ncommunication we look at the effect of adiabatically twisting a single molecule\nmagnet embedded in a graphene monolayer. Surprisingly, we see that pure spin\ncurrents (zero charge current) can be generated from the system via quantum\npumping. In addition we also see spin selective current can also be pumped from\nthe system. The pure spin current seen is quite resilient to temperature while\ndisorder has a limited effect. Further the direction of these spin pumped\ncurrents can be easily and exclusively controlled by the magnetization of the\nsingle molecule magnet with disorder having no effect on the magnetization\ncontrol of the pumped spin currents."
    },
    {
        "anchor": "Effective mass theory for the anisotropic exciton in 2D crystals:\n  Application to phosphorene: We present a theoretical study of the exciton binding energy for anisotropic\ntwo-dimensional crystals. We obtain analytical expressions from variational\nwave functions in different limits of the screening length to exciton size\nratio and compare them with numerical solutions, both variational and exact. As\nan example, we apply these results to phosphorene, a monolayer of black\nphosphorous. Aided by density functional theory calculations for the evaluation\nof the two-dimensional polarizability, our analytical solution for the exciton\nbinding energy gives a result which is very close to the numerical ones and, in\nturn, is comparable to the experimental value, as recently reported.",
        "positive": "Non-linear spin-wave excitation at low bias fields: Non-linear magnetization dynamics is essential for the operation of many\nspintronics devices. For microwave assisted switching of magnetic elements the\nlow field regime is of particular interest. In addition a large number of\nexperiments uses high amplitude FMR in order to generate d.c. currents via spin\npumping mechanism. Here we use time resolved X-ray magnetic circular dichroism\nexperiments to determine the number density of excited magnons in magnetically\nsoft Ni_80Fe_20 thin films at small bias fields and large rf-excitation\namplitudes. Our data shows that the common model of non-linear ferromagnetic\nresonance is not suitable to describe the low bias field limit. Here we derive\na new model of parametric spin-wave excitation which correctly predicts\nthreshold amplitudes and decay rates also at low bias fields. In fact a new\nseries of critical modes with amplitude phase oscillations is found,\ngeneralizing the theory of parametric spin-wave excitation."
    },
    {
        "anchor": "Non-equilibrium steady state of a driven levitated particle with\n  feedback cooling: Laser trapped nanoparticles have been recently used as model systems to study\nfundamental relations holding far from equilibrium. Here we study, both\nexperimentally and theoretically, a nanoscale silica sphere levitated by a\nlaser in a low density gas. The center of mass motion of the particle is\nsubjected, at the same time, to feedback cooling and a parametric modulation\ndriving the system into a non-equilibrium steady state. Based on the Langevin\nequation of motion of the particle, we derive an analytical expression for the\nenergy distribution of this steady state showing that the average and variance\nof the energy distribution can be controlled separately by appropriate choice\nof the friction, cooling and modulation parameters. Energy distributions\ndetermined in computer simulations and measured in a laboratory experiment\nagree well with the analytical predictions. We analyse the particle motion also\nin terms of the quadratures and find thermal squeezing depending on the degree\nof detuning.",
        "positive": "Designing quantum dots for solotronics: Solotronics, optoelectronics based on solitary dopants, is an emerging field\nof research and technology reaching the ultimate limit of miniaturization. It\naims at exploiting quantum properties of individual ions or defects embedded in\na semiconductor matrix. As already shown, optical control of a spin of a\nmagnetic ion is feasible employing photo-generated carriers confined in a\nquantum dot. A non-radiative recombination, regarded as a severe problem,\nlimited development of quantum dots with magnetic ions. Our photoluminescence\nstudies on, so far unexplored, individual CdTe dots with single cobalt ions and\nindividual CdSe dots with single manganese ions show, however, that even if\nenergetically allowed, the single ion related non-radiative recombination is\nnegligible in such zero-dimensional structures. This opens solotronics for a\nwide range of even not yet considered systems. Basing on the results of our\nsingle spin relaxation experiments and on the material trends, we identify\noptimal magnetic ion-quantum dot systems for implementation of a single-ion\nbased spin memory."
    },
    {
        "anchor": "Broadband Absorbers and Selective Emitters based on Plasmonic Brewster\n  Metasurfaces: We discuss the possibility of realizing utlrabroadband omnidirectional\nabsorbers and angularly selective coherent thermal emitters based on properly\npatterned plasmonic metastructures. Instead of relying on resonant\nconcentration effects that inherently limit the bandwidth, we base our design\non the combination of two inherently nonresonant effects: plasmonic Brewster\nfunneling and adiabatic plasmonic focusing. With this approach, we demonstrate\ncompact, broadband absorption and emission spanning terahertz, infrared and\noptical frequencies, ideal for various energy and defense applications.",
        "positive": "Designing three-dimensional flat bands in nodal-line semimetals: Electrons with large kinetic energy have a superconducting instability for\ninfinitesimal attractive interactions. Quenching the kinetic energy and\ncreating a flat band renders an infinitesimal repulsive interaction the\nrelevant perturbation. Thus, flat band systems are an ideal platform to study\nthe competition of superconductivity and magnetism and their possible\ncoexistence. Recent advances in the field of twisted bilayer graphene highlight\nthis in the context of two-dimensional materials. Two dimensions, however, put\nsevere restrictions on the stability of the low-temperature phases due to\nenhanced fluctuations. Only three-dimensional flat bands can solve the\nconundrum of combining the exotic flat-band phases with stable order existing\nat high temperatures. Here, we present a way to generate such flat bands\nthrough strain engineering in topological nodal-line semimetals. We present\nanalytical and numerical evidence for this scenario and study the competition\nof the arising superconducting and magnetic orders as a function of externally\ncontrolled parameters. We show that the order parameter is rigid because the\nquantum geometry of the Bloch wave functions leads to a large superfluid\nstiffness. Using density-functional theory and numerical tight-binding\ncalculations we further apply our theory to strained rhombohedral graphite and\nCaAgP materials."
    },
    {
        "anchor": "Strong electronic winds blowing under liquid flows on carbon surfaces: The interface between a liquid and a solid is the location of plethora of\nintrincate mechanisms at the nanoscale, at the root of their specific emerging\nproperties in natural processes or technological applications. However, while\nthe structural properties and chemistry of interfaces have been intensively\nexplored, the effect of the solid-state electronic transport at the fluid\ninterface has been broadly overlooked up to now. It has been reported that\nwater flowing against carbon-based nanomaterials, such as carbon nanotubes or\ngraphene sheets, does induce electronic currents, but the mechanism at stake\nremains controversial. Here, we unveil the molecular mechanisms underlying the\nhydro-electronic couplings by investigating the electronic conversion under\nflow at the nanoscale. We use a tuning fork-Atomic Force Microscope (AFM) to\ndeposit and displace a micrometric droplet of both ionic and non-ionic liquids\non a multilayer graphene sample, while recording the electrical current across\nthe carbon flake. We report measurements of an oscillation-induced current\nwhich is several orders of magnitude larger than previously reported for water\non carbon , and further boosted by the presence of surface wrinkles on the\ncarbon layer. Our results point to a peculiar momentum transfer mechanism\nbetween fluid molecules and charge carriers in the carbon walls mediated by\nphonon excitations in the solid. Our findings pave the way for active control\nof fluid transfer at the nanoscale by harnessing the complex interplay between\ncollective excitations in the solid and the molecules in the fluid.",
        "positive": "Observation of a Berry phase anti-damping spin-orbit torque: Recent observations of current-induced magnetization switching at\nferromagnet/normal-conductor interfaces have important consequences for future\nmagnetic memory technology. In one interpretation, the switching originates\nfrom carriers with spin-dependent scattering giving rise to a relativistic\nanti-damping spin-orbit torque (SOT) in structures with broken space-inversion\nsymmetry. The alternative interpretation combines the relativistic spin Hall\neffect (SHE), making the normal-conductor an injector of a spin-current, with\nthe non-relativistic spin-transfer torque (STT) in the ferromagnet. Remarkably,\nthe SHE in these experiments originates from the Berry phase effect in the band\nstructure of a clean crystal and the anti-damping STT is also based on a\ndisorder-independent transfer of spin from carriers to magnetization. Here we\nreport the observation of an anti-damping SOT stemming from an analogous Berry\nphase effect to the SHE. The SOT alone can therefore induce magnetization\ndynamics based on a scattering-independent principle. The ferromagnetic\nsemiconductor (Ga,Mn)As we use has a broken space-inversion symmetry in the\ncrystal. This allows us to consider a bare ferromagnetic element which\neliminates by design any SHE related contribution to the spin torque. We\nprovide an intuitive picture of the Berry phase origin of the anti-damping SOT\nand a microscopic modeling of measured data."
    },
    {
        "anchor": "Exciton band structure of monolayer MoS2: We address the properties of excitons in monolayer MoS$_2$ from a theoretical\npoint of view, showing that low-energy excitonic states occur both at the\nBrillouin zone center and at the Brillouin-zone corners, that binding energies\nat the Brillouin-zone center deviate strongly from the $(n-1/2)^{-2}$ pattern\nof the two-dimensional hydrogenic model, and that the valley-degenerate exciton\ndoublet at the Brillouin-zone center splits at finite momentum into an upper\nmode with non-analytic linear dispersion and a lower mode with quadratic\ndispersion. Although monolayer MoS$_2$ is a direct-gap semiconductor when\nclassified by its quasiparticle band structure, it may well be an indirect gap\nmaterial when classified by its excitation spectra.",
        "positive": "Extracting the scaling dimension of quantum Hall quasiparticles from\n  current correlations: Fractional quantum Hall quasiparticles are generally characterized by two\nquantum numbers: electric charge $Q$ and scaling dimension $\\Delta$. For the\nsimplest states (such as the Laughlin series) the scaling dimension determines\nthe quasiparticle's anyonic statistics (the statistical phase\n$\\theta=2\\pi\\Delta$). For more complicated states (featuring counterpropagating\nmodes or non-Abelian statistics) knowing the scaling dimension is not enough to\nextract the quasiparticle statistics. Nevertheless, even in those cases knowing\nthe scaling dimension facilitates distinguishing different candidate theories\nfor describing the quantum Hall state at a particular filling (such as\nPH-Pfaffian and anti-Pfaffian at $\\nu=5/2$). Here we propose a scheme for\nextracting the scaling dimension of quantum Hall quasiparticles from thermal\ntunneling noise produced at a quantum point contact. Our scheme makes only\nminimal assumptions about the edge structure and features the level of\nrobustness, simplicity, and model independence comparable to extracting the\nquasiparticle charge from tunneling shot noise."
    },
    {
        "anchor": "Knight shift detection using gate-induced decoupling of the hyperfine\n  interaction in quantum Hall edge channels: A method for the observation of the Knight shift in nanometer-scale region in\nsemiconductors is developed using resistively detected nuclear magnetic\nresonance (RDNMR) technique in quantum Hall edge channels. Using a gate-induced\ndecoupling of the hyperfine interaction between electron and nuclear spins, we\nobtain the RDNMR spectra with or without the electron-nuclear spin coupling. By\na comparison of these two spectra, the values of the Knight shift can be given\nfor the nuclear spins polarized dynamically in the region between the relevant\nedge channels in a single two-dimensional electron system, indicating that this\nmethod has a very high sensitivity compared to a conventional NMR technique.",
        "positive": "Transport signatures of Van Hove singularities in mesoscopic twisted\n  bilayer graphene: Magic-angle twisted bilayer graphene exhibits quasi-flat low-energy bands\nwith Van Hove singularities close to the Fermi level. These singularities play\nan important role in the exotic phenomena observed in this material, such as\nsuperconductivity and magnetism, by amplifying electronic correlation effects.\nIn this work, we study the correspondence of four-terminal conductance and the\nFermi surface topology as a function of the twist angle, pressure, and energy\nin mesoscopic, ballistic samples of small-angle twisted bilayer graphene. We\nestablish a correspondence between features in the wide-junction conductance\nand the presence of van Hove singularities in the density of states. Moreover,\nwe identify additional transport features, such as a large, pressure-tunable\nminimal conductance, conductance peaks coinciding with non-singular band\ncrossings, and unusually large conductance oscillations as a function of the\nsystem size. Our results suggest that twisted bilayer graphene close the magic\nangle is a unique system featuring simultaneously large conductance due to the\nquasi-flat bands, strong quantum nonlinearity due to the Van Hove singularities\nand high sensitivity to external parameters, which could be utilized in\nhigh-frequency device applications and sensitive detectors."
    },
    {
        "anchor": "Emission characteristics of laser-driven dissipative coupled-cavity\n  systems: We consider a laser-driven and dissipative system of two coupled cavities\nwith Jaynes-Cummings nonlinearity. In particular, we investigate both\nincoherent and coherent laser driving, corresponding to different experimental\nsituations. We employ Arnoldi time evolution as a numerical tool to solve\nexactly the many-body master equation describing the non-equilibrium quantum\nsystem. We evaluate the fluorescence spectrum and the spectrum of the\nsecond-order correlation function of the emitted light field. Finally, we\nrelate the measured spectra of the dissipative quantum system to excitations of\nthe corresponding non-dissipative quantum system. Our results demonstrate how\nto interpret spectra obtained from dissipative quantum systems and specify what\ninformation is contained therein.",
        "positive": "Size and Shape Effects in the Orbital Magnetization of TMDs Monolayers: The intrinsic orbital magnetization of a TMD monolayer is usually calculated\nfor a plane unbounded system without mentioning the geometrical shape of\nsamples and boundary conditions (BCs) for electron wave functions. The method\nof calculations includes allowing for the Berry curvature contribution also in\nthe case when the system is described by the two-band minimal model [9]. In the\npresent paper, we show that the geometrical and topological properties of the\nspecimen, as well as the BCs, play an important role in the problem of\nmagnetization even for a macroscopic specimen."
    },
    {
        "anchor": "Dynamics of a Qubit in a High-Impedance Transmission Line from a Bath\n  Perspective: We investigate quantum dynamics of a generic model of light-matter\ninteraction in the context of high impedance waveguides, focusing on the\nbehavior of the emitted photonic states, in the framework of the spin-boson\nmodel Quantum quenches as well as scattering of an incident coherent pulse are\nstudied using two complementary methods. First, we develop an approximate\nansatz for the electromagnetic waves based on a single multimode coherent state\nwavefunction; formally, this approach combines ideas from adiabatic\nrenormalization, the Born-Markov approximation, and input-output theory.\nSecond, we present numerically exact results for scattering of a weak intensity\npulse by using NRG calculations. NRG provides a benchmark for any linear\nresponse property throughout the ultra-strong coupling regime. We find that in\na sudden quantum quench, the coherent state approach produces physical\nartifacts, such as improper relaxation to the steady state. These previously\nunnoticed problems are related to the simplified form of the ansatz that\ngenerates spurious correlations within the bath. In the scattering problem, NRG\nis used to find the transmission and reflection of a single photon, as well as\nthe inelastic scattering of that single photon. Simple analytical formulas are\nestablished and tested against the NRG data that predict quantitatively the\ntransport coefficients for up to moderate environmental impedance. These\nformulas resolve pending issues regarding the presence of inelastic losses in\nthe spin-boson model near absorption resonances, and could be used for\ncomparison to experiments in Josephson waveguide QED. Finally, the scattering\nresults using the coherent state wavefunction approach are compared favorably\nto the NRG results for very weak incident intensity. We end our study by\npresenting results at higher power where the response of the system is\nnonlinear.",
        "positive": "Spin transfer in a ferromagnet-quantum dot and tunnel barrier coupled\n  Aharonov-Bohm ring system with Rashba spin-orbit interactions: The spin transfer effect in ferromagnet-quantum dot (insulator)-ferromagnet\nAharonov-Bohm (AB) ring system with Rashba spin-orbit (SO) interactions is\ninvestigated by means of Keldysh nonequilibrium Green function method. It is\nfound that both the magnitude and direction of the spin transfer torque (STT)\nacting on the right ferromagnet electrode can be effectively controlled by\nchanging the magnetic flux threading the AB ring or the gate voltage on the\nquantum dot. The STT can be greatly augmented by matching a proper magnetic\nflux and an SO interaction at a cost of low electrical current. The STT,\nelectrical current, and spin current are uncovered to oscillate with the\nmagnetic flux. The present results are expected to be useful for information\nstorage in nanospintronics."
    },
    {
        "anchor": "Circumventing the polariton bottleneck via dark excitons in 2D\n  semiconductors: Efficient scattering into the exciton polariton ground state is a key\nprerequisite for generating Bose-Einstein condensates and low-threshold\npolariton lasing. However, this can be challenging to achieve at low densities\ndue to the polariton bottleneck effect that impedes phonon-driven scattering\ninto low-momentum polariton states. The rich exciton landscape of transition\nmetal dichalcogenides (TMDs) provides potential intervalley scattering pathways\nvia dark excitons to rapidly populate these polaritons. Here, we present a\nmicroscopic study exploring the time- and momentum-resolved relaxation of\nexciton polaritons supported by a \\ce{MoSe2} monolayer integrated within a\nFabry-Perot cavity. By exploiting phonon-assisted transitions between\nmomentum-dark excitons and the lower polariton branch, we demonstrate that it\nis possible to circumvent the bottleneck region and efficiently populate the\npolariton ground state. Furthermore, this intervalley pathway is predicted to\ngive rise to, yet unobserved, angle-resolved phonon sidebands in\nlow-temperature photoluminescence spectra that are associated with\nmomentum-dark excitons. This represents a distinctive experimental signature\nfor efficient phonon-mediated polariton-dark-exciton interactions.",
        "positive": "Electrically tunable flat bands with layer-resolved charge distribution\n  in twisted monolayer-bilayer graphene: At a small twist angle, exotic electronic properties emerge in twisted\nmonolayer-bilayer graphene (aAB), including electrically switchable magnetic\norder and correlated insulating states. These fascinating many-body phenomena\nmanifest when the low-energy bands feature a narrow band width. In this study,\nwe examine the electronic structure of aAB using first-principles calculations\ncombined with an accurate tight-binding model. We find that the presence of an\nintrinsic polarization greatly modifies the low-energy bands of aAB.\nFurthermore, the low-energy bands reach a minimum width at a quasi-magic angle\nand feature a layer-dependent charge localization and delocalization pattern.\nIn the presence of an electric field, an energy gap opens only if lattice\nrelaxation is taken into account. The particle-hole asymmetry in aAB further\nleads to flatter conduction bands compared with the valence bands, with an\nelectrically tunable band width and band gap, and a switchable\nsublattice-dependent charge localization and delocalization pattern."
    },
    {
        "anchor": "Non-Hermitian Topological Invariants in Real Space: The topology of non-Hermitian systems is drastically shaped by the\nnon-Hermitian skin effect, which leads to the generalized bulk-boundary\ncorrespondence and non-Bloch band theory. The essential part in formulations of\nbulk-boundary correspondence is a general and computable definition of\ntopological invariants. In this paper, we introduce a construction of\nnon-Hermitian topological invariants based directly on real-space\nwavefunctions, which provides a general and straightforward approach for\ndetermining non-Hermitian topology. As an illustration, we apply this\nformulation to several representative models of non-Hermitian systems,\nefficiently obtaining their topological invariants in the presence of\nnon-Hermitian skin effect. Our formulation also provides a dual picture of the\nnon-Bloch band theory based on the generalized Brillouin zone, offering a\nunique perspective of bulk-boundary correspondence.",
        "positive": "Vertical quantum wire realized with double cleaved-edge overgrowth: A quantum wire is fabricated on (001)-GaAs at the intersection of two\novergrown cleaves. The wire is contacted at each end to n+ GaAs layers via\ntwo-dimensional (2D) leads. A sidegate controls the density of the wire\nrevealing conductance quantization. The step height is strongly reduced from\n2e^2/h due to the 2D-lead series resistance. We characterize the 2D density and\nmobility for both cleave facets with four-point measurements. The density on\nthe first facet is modulated by the substrate potential, depleting a 2um wide\nstrip that defines the wire length. Micro-photoluminescence shows an extra peak\nconsistent with 1D electron states at the corner."
    },
    {
        "anchor": "Resonant Spin and Charge Hall Effects in 2D Electron Gas with Unequal\n  Rashba and Dresselhaus Spin-Orbit Couplings under a Perpendicular Magnetic\n  Field: We have investigated the complex two-dimensional electron system with unequal\nRashba and Dresselhaus spin-orbit interactions in the presence of a\nperpendicular magnetic field. The spin polarizations are obtained in a wide\nrange of magnetic fields. It is shown that such a system is hard to be\nmagnetized. We also find that the resonant charge and spin Hall conductances\noccurs simultaneously at a certain magnetic field, at which two (nearly)\ndegenerate Landau levels are filled partly. The resonant Hall effects are\nuniversal in this type of semiconductor materials, and could have potential\napplication for semiconductor spintronics.",
        "positive": "Current-driven skyrmion motion in granular films: Current-driven skyrmion motion in random granular films is investigated with\ninteresting findings. For a given current, there exists a critical disorder\nstrength below which its transverse motion could either be boosted below a\ncritical damping or be hindered above the critical damping, resulting in\ncurrent and disorder dependences of skyrmion Hall angle. The boosting comes\nmainly from the random force that is opposite to the driving force (current).\nThe critical damping depends on the current density and disorder strength.\nHowever, the longitudinal motion of a skyrmion is always hindered by the\ndisorder. Above the critical disorder strength, skyrmions are pinned. The\ndisorder-induced random force on a skyrmion can be classified as static and\nkinetic ones, similar to the friction force in the Newtonian mechanics. In the\npinning phase, the static (pinning) random force is transverse to the current\ndensity. The kinetic random force is opposite to the skyrmion velocity when\nskyrmions are in motion. Furthermore, we provide strong evidences that the\nThiele equation can perfectly describe skyrmion dynamics in granular films.\nThese findings provide insight to skyrmion motion and should be important for\nskyrmiontronics."
    },
    {
        "anchor": "Valley polarized relaxation and upconversion luminescence from\n  Tamm-Plasmon Trion-Polaritons with a MoSe2 monolayer: Transition metal dichalcogenides represent an ideal testbed to study\nexcitonic effects, spin-related phenomena and fundamental light-matter coupling\nin nanoscopic condensed matter systems. In particular, the valley degree of\nfreedom, which is unique to such direct band gap monolayers with broken\ninversion symmetry, adds fundamental interest in these materials. Here, we\nimplement a Tamm-plasmon structure with an embedded MoSe2 monolayer and study\nthe formation of polaritonic quasi-particles. Strong coupling conditions\nbetween the Tamm-mode and the trion resonance of MoSe2 are established,\nyielding bright luminescence from the polaritonic ground state under\nnon-resonant optical excitation. We demonstrate, that tailoring the\nelectrodynamic environment of the monolayer results in a significantly\nincreased valley polarization. This enhancement can be related to change in\nrecombination dynamics shown in time-resolved photoluminescence measurements.\nWe furthermore observe strong upconversion luminescence from resonantly excited\npolariton states in the lower polariton branch. This upconverted polariton\nluminescence is shown to preserve the valley polarization of the\ntrion-polariton, which paves the way towards combining spin-valley physics and\nexciton scattering experiments.",
        "positive": "Pseudospin vortex-antivortex states with interwoven spin textures in\n  double layer quantum Hall systems: Recent experiments on strongly correlated bilayer quantum Hall systems\nstrongly suggest that, contrary to the usual assumption, the electron spin\ndegree of freedom is not completely frozen either in the quantum Hall or in the\ncompressibles states that occur at filling factor $\\nu =1.$ These experiments\nimply that the quasiparticles at $\\nu =1$ could have both spin and pseudospin\ntextures i.e. they could be CP$^{3}$ skyrmions. Using a microscopic\nunrestricted Hartree-Fock approximation, we compute the energy of several\ncrystal states with spin, pseudospin and mixed spin-pseudospin textures around\n$\\nu =1$ as a function of interlayer separation $d$ for different values of\ntunneling ($\\Delta_{SAS}$), Zeeman ($\\Delta_{Z}$), and bias ($\\Delta_{b}$)\nenergies. We show that in some range of these parameters, crystal states\ninvolving a certain amount of spin depolarization have lower energy than the\nfully spin polarized crystals. We study this depolarization dependence on\n$d,\\Delta_{SAS},\\Delta_{Z}$ and $\\Delta_{b}$ and discuss how it can lead to the\nfast NMR relaxation rate observed experimentally."
    },
    {
        "anchor": "Coulomb-driven organization and enhancement of spin-orbit fields in\n  collective spin excitations: Spin-orbit (SO) fields in a spin-polarized electron gas are studied by\nangle-resolved inelastic light scattering on a CdMnTe quantum well. We\ndemonstrate a striking organization and enhancement of SO fields acting on the\ncollective spin excitation (spin-flip wave). While individual electronic SO\nfields have a broadly distributed momentum dependence, giving rise to\nD'yakonov-Perel' dephasing, the collective spin dynamics is governed by a\nsingle collective SO field which is drastically enhanced due to many-body\neffects. The enhancement factor is experimentally determined. These results\nprovide a powerful indication that these constructive phenomena are universal\nto collective spin excitations of conducting systems.",
        "positive": "Transport properties of nanosystems with conventional and unconventional\n  charge density waves: We report a systematic study of transport properties of nanosytems with\ncharge density waves. We demonstrate, how the presence of density waves\nmodifies the current-voltage characteristics. On the other hand hand, we show\nthat the density waves themselves are strongly affected by the applied voltage.\nThis self-consistent problem is solved within the formalism of the\nnonequilibrium Green functions. The conventional charge density waves occur\nonly for specific, periodically distributed ranges of the voltage. Apart from\nthe low voltage regime, they are incommensurate and the corresponding wave\nvectors decrease discontinuously when the voltage increases."
    },
    {
        "anchor": "Quantum-classical correspondence for a dc-biased cavity\n  resonator--Cooper-pair transistor system: We investigate the quantum versus classical dynamics of a microwave\ncavity-coupled-Cooper pair transistor (CPT) system, where an applied dc bias\ncauses the system to self-oscillate via the ac Josephson effect. Varying the dc\nbias allows the self-oscillation frequency to be tuned. An unusual feature of\nthe system design is that the dc bias does not significantly affect the high\nquality factor of the cavity mode to which the CPT predominantly couples. The\nCPT-cavity mode system has a mechanical analogue involving a driven coupled\npendulum-oscillator system. The corresponding, nonlinear classical dynamical\nequations exhibit chaotic, as well as aperiodic motions depending on the\ninitial conditions and the nature and strengths of the damping/noise forces.\nThe quantum master equation exhibits such phenomena as dynamical tunneling and\nthe generation of non-classical states from initial classical states. Obviating\nthe need for an external ac-drive line, which typically is harder to noise\nfilter than a dc bias line, the self-oscillating system described here has\nconsiderable promise for demonstrating macroscopic quantum dynamical behavior.",
        "positive": "On-surface synthesis and collective spin excitations of a\n  triangulene-based nanostar: Triangulene nanographenes are open-shell molecules with predicted high spin\nstate due to the frustration of their conjugated network. Their long-sought\nsynthesis became recently possible over a metal surface. Here, we present a\nmacrocycle formed by six [3]triangulenes, which was obtained by combining the\nsolution synthesis of a dimethylphenyl-anthracene cyclic hexamer and the\non-surface cyclodehydrogenation of this precursor over a gold substrate. The\nresulting triangulene nanostar exhibits a collective spin state generated by\nthe interaction of its 12 unpaired {\\pi}-electrons along the conjugated\nlattice, corresponding to the antiferromagnetic ordering of six S = 1 sites\n(one per triangulene unit). Inelastic electron tunneling spectroscopy resolved\nthree spin excitations connecting the singlet ground state with triplet states.\nThe nanostar behaves close to predictions from the Heisenberg model of a S = 1\nspin ring, representing a unique system to test collective spin modes in cyclic\nsystems."
    },
    {
        "anchor": "Broadband Focusing of Acoustic Plasmons in Graphene with an Applied\n  Current: Non-reciprocal plasmons in current-driven, isotropic, and homogenous graphene\nwith proximal metallic gates is theoretically explored. Nearby metallic gates\nscreen the Coulomb interactions, leading to linearly dispersive acoustic\nplasmons residing close to its particle-hole continuum counterpart. We show\nthat the applied bias leads to spectral broadband focused plasmons whose\nresonance linewidth is dependent on the angular direction relative to the\ncurrent flow due to Landau damping. We predict that forward focused\nnon-reciprocal plasmons are possible with accessible experimental parameters\nand setup.",
        "positive": "Photonic heat rectification in a coupled qubits system: We theoretically investigate a quantum heat diode based on two interacting\nflux qubits coupled to two heat baths. Rectification of heat currents is\nachieved by asymmetrically coupling the qubits to the reservoirs modelled as\ndissipative $RLC$ resonators. We find that the coherent interaction between the\nqubits can be exploited to enhance the rectification factor, which otherwise\nwould be constrained by the baths temperatures and couplings. Remarkably high\nvalues of rectification ratio up to $\\mathcal R \\sim 3.5$ can be obtained for\nrealistic system parameters, with an enhancement up to $\\sim 230\\%$ compared to\nthe non-interacting case. The system features the possibility of manipulating\nboth the rectification amplitude and direction, allowing for an enhancement or\nsuppression of the heat flow to a chosen bath. For the regime of parameters in\nwhich rectification is maximized, we find a significant increase of the\nrectification above a critical interaction value which corresponds to the onset\nof a non vanishing entanglement in the system. Finally, we discuss the\ndependence of the rectification factor on the bath temperatures and couplings."
    },
    {
        "anchor": "Suppression of Electromagnetic Crosstalk by Differential Excitation for\n  SAW Generation: Surface acoustic waves (SAWs) hold a vast potential in various fields such as\nspintronics, quantum acoustics, and electron-quantum optics, but an\nelectromagnetic wave emanating from SAW generation circuits has often been a\nmajor hurdle. Here, we investigate a differential excitation method of\ninterdigital transducers (IDTs) to generate SAWs while reducing the\nelectromagnetic wave. The results show that electromagnetic waves are\nsuppressed by more than 90% in all directions. This suppression overcomes the\noperating limits and improves the scalability of SAW systems. Our results\npromise to facilitate the development of SAW-based applications in a wide range\nof research fields.",
        "positive": "Splitting of Dirac cones in HgTe quantum wells: Effects of\n  crystallographic orientation, interface-, bulk-, and structure-inversion\n  asymmetry: We develop a microscopic theory of the fine structure of Dirac states in\n$(0lh)$-grown HgTe/CdHgTe quantum wells (QWs), where $l$ and $h$ are the Miller\nindices. It is shown that bulk, interface, and structure inversion asymmetry\ncauses the anticrossing of levels even at zero in-plane wave vector and lifts\nthe Dirac state degeneracy. In the QWs of critical thickness, the two-fold\ndegenerate Dirac cone gets split into non-degenerate Weyl cones. The splitting\nand the Weyl point positions dramatically depend on the QW crystallographic\norientation. We calculate the splitting parameters related to bulk, interface,\nand structure inversion asymmetry and derive the effective Hamiltonian of the\nDirac states. Further, we obtain an analytical expression for the energy\nspectrum and discuss the spectrum for (001)-, (013)- and (011)-grown QWs."
    },
    {
        "anchor": "Scattering in Monolayer Molybdenum Disulfide Quantum Dot: We investigate the propagation of electrons in a circular quantum dot of\nmonolayer Molybdenium disulfide MoS_2, subjected to an electric potential.\nUsing the continuum model, we present analytical expressions for the\neigenstates, scattering coefficients, scattering efficiency, and radial\ncomponent of the reflected current and electron density. We identify two\nscattering regimes as a function of physical parameters such as incident\nelectronic energy, potential barrier, and quantum dot radius. For the incident\nelectron low energy, we show that there is an appearance of scattering\nresonances. Also, we note that the Far-field scattered current has distinct\npreferred scattering directions.",
        "positive": "Twistable electronics with dynamically rotatable heterostructures: The electronic properties of two-dimensional materials and their\nheterostructures can be dramatically altered by varying the relative angle\nbetween the layers. This makes it theoretically possible to realize a new class\nof twistable electronics in which device properties can be manipulated\non-demand by simply rotating the structure. Here, we demonstrate a new device\narchitecture in which a layered heterostructure can be dynamically twisted, in\nsitu. We study graphene encapsulated by boron nitride where at small rotation\nangles the device characteristics are dominated by coupling to a large\nwavelength Moir\\'e superlattice. The ability to investigate arbitrary rotation\nangle in a single device reveals new features in the optical, mechanical and\nelectronic response in this system. Our results establish the capability to\nfabricate twistable electronic devices with dynamically tunable properties."
    },
    {
        "anchor": "Interference features in scanning gate conductance maps of quantum point\n  contacts with disorder: We consider quantum point contacts (QPCs) defined within disordered\ntwo-dimensional electron gases as studied by scanning gate microscopy. We\nevaluate the conductance maps in the Landauer approach and wave function\npicture of electron transport for samples with both low and high electron\nmobility at finite temperatures. We discuss the spatial distribution of the\nimpurities in the context of the branched electron flow. We reproduce the\nsurprising temperature stability of the experimental interference fringes far\nfrom the QPC. Next, we discuss -- previously undescribed -- funnel-shaped\nfeatures that accompany splitting of the branches visible in previous\nexperiments. Finally, we study elliptical interference fringes formed by an\ninterplay of scattering by the point-like impurities and by the scanning probe.\nWe discuss the details of the elliptical features as functions of the tip\nvoltage and the temperature, showing that the first interference fringe is very\nrobust against the thermal widening of the Fermi level. We present a simple\nanalytical model that allows for extraction of the impurity positions and the\nelectron gas depletion radius induced by the negatively charged tip of the\natomic force microscope, and apply this model on experimental scanning gate\nimages showing such elliptical fringes.",
        "positive": "Length-scale independent skyrmion and meron Hall angles: Motivated by the recent observation [Zeissler et al, Nature Comm. 11, 428\n(2020)] of enigmatic radius-independent skyrmion Hall angle in chiral magnets,\nwe derive skyrmion Hall angle based on the recent solution of skyrmions\ncharacterized by the sole length scale determined with the\nDzyaloshinskii-Moriya interaction strength and applied magnetic field. We find\nthat the skyrmion Hall angle is independent of input current density and the\nlength-scale which determines the radius of a skyrmion.This is corroborated\nwith the single length-scale dependent skyrmion profile which is the solution\nof the Euler equation of polar angle representing magnetization. Although the\nmagnitude of Hall angle may change with the change of profile (shape) of the\nskyrmion, it remains unchanged for a particular profile. With the application\nof tunable current along mutually perpendicular directions, this property\nenables us to propose an experimental setup by which the transverse motion of a\nskyrmion can be restricted so that the skyrmion can only traverse\nlongitudinally. We further find the length-scale and input-current density\nindependent Hall angles for merons where their transverse motion will be\nopposite depending on whether the spin at their centers are up or down, in\nagreement with an experiment."
    },
    {
        "anchor": "All-optical generation and detection of sub-picosecond ac spin current\n  pulses in GaAs: Sub-picosecond ac spin current pulses are generated optically in GaAs bulk\nand quantum wells at room temperature and 90K through quantum interference\nbetween one-photon and two-photon absorptions driven by two phase-locked\nultrafast laser pulses that are both circularly polarized. The dynamics of the\ncurrent pulses are detected optically by monitoring in real time and real space\nnanoscale motion of electrons with high-resolution pump-probe techniques.",
        "positive": "Inelastic cotunneling in quantum dots and molecules with weakly broken\n  degeneracies: We calculate the nonlinear cotunneling conductance through interacting\nquantum dot systems in the deep Coulomb blockade regime using a rate equation\napproach based on the T-matrix formalism, which shows in the concerned regions\nvery good agreement with a generalized master equation approach. Our focus is\non inelastic cotunneling in systems with weakly broken degeneracies, such as\ncomplex quantum dots or molecules. We find for these systems a characteristic\ngate dependence of the non-equilibrium cotunneling conductance. While on one\nside of a Coulomb diamond the conductance decreases after the inelastic\ncotunneling threshold towards its saturation value, on the other side it\nincreases monotonously even after the threshold. We show that this behavior\noriginates from an asymmetric gate voltage dependence of the effective\ncotunneling amplitudes."
    },
    {
        "anchor": "Electric field induced color switching in colloidal quantum dot\n  molecules at room temperature: Colloidal semiconductor quantum dots are robust emitters implemented in\nnumerous prototype and commercial optoelectronic devices. However, active\nfluorescence color tuning, achieved so far by electric-field induced Stark\neffect, has been limited to a small spectral range, and accompanied by\nintensity reduction due to the electron-hole charge separation effect.\nUtilizing quantum dot molecules that manifest two coupled emission centers, we\npresent a novel electric-field induced instantaneous color switching effect.\nReversible emission color switching without intensity loss is achieved on a\nsingle particle level, as corroborated by correlated electron microscopy\nimaging. Simulations establish that this is due to the electron wavefunction\ntoggling between the two centers dictated by the electric-field and affected by\nthe coupling strength. The quantum dot molecules manifesting two coupled\nemission centers may be tailored to emit distinct colors, opening the path for\nsensitive field sensing and color switchable devices such as a novel pixel\ndesign for displays or an electric field color tunable single photon source.",
        "positive": "Optimal control of electromagnetic field using metallic nanoclusters: The dielectric properties of metallic nanoclusters in the presence of an\napplied electromagnetic field are investigated using non-local linear response\ntheory. In the quantum limit we find a non-trivial dependence of the induced\nfield and charge distribution on the spatial separation between the clusters\nand on the frequency of the driving field. Using a genetic algorithm, these\nquantum functionalities are exploited to custom-design sub-wavelength lenses\nwith a frequency controlled switching capability."
    },
    {
        "anchor": "The electronic structure of intrinsic magnetic topological insulator\n  MnBi2Te4 quantum wires: The ferromagnetic and antiferromagnetic nanostructure are crucial for\nfundamental spintronics devices, motivated by its potential application in\nspintronics, we theoretically investigate the electronic structure of the\nferromagnetic and antiferromagnetic phases of the cylindrical intrinsically\nmagnetic topological insulator $\\mathrm{MnBi_{2}Te_{4}}$ quantum wires for both\ncases. We demonstrate that a few surface states exist between the bulk band gap\nin the ferromagnetic phase, with only one spin branch. In the antiferromagnetic\nphase, we show that three coexistent states exist between the energy gaps of\nthe quantum wires.",
        "positive": "Tunable coupling of qubits: nonadiabatic corrections: We analyze the coupling of qubits mediated by a tunable and fast element\nbeyond the adiabatic approximation. The nonadiabatic corrections are important\nand even dominant in parts of the relevant parameter range. As an example, we\nconsider the tunable capacitive coupling between two charge qubits mediated by\na gated Josephson junction, as suggested by Averin and Bruder. The\nnonadiabatic, inductive contribution persists when the capacitive coupling is\ntuned to zero. On the other hand, the total coupling can be turned off (in the\nrotating wave approximation) if the qubits are operated at symmetry points."
    },
    {
        "anchor": "Electronic States and Transport Phenomena in Quantum Dot Systems: Electronic states and transport phenomena in semiconductor quantum dots are\nstudied theoretically. Taking account of the electron-electron Coulomb\ninteraction by the exact diagonalization method, the ground state and low-lying\nexcited states are calculated as functions of magnetic field. Using the\nobtained many-body states, we discuss the temperature dependence of the\nconductance peaks in the Coulomb oscillation. In the Coulomb blockade region,\nelastic and inelastic cotunneling currents are evaluated under finite bias\nvoltages. The cotunneling conductance is markedly enhanced by the Kondo effect.\nIn coupled quantum dots, molecular orbitals and electronic correlation\ninfluence the transport properties.",
        "positive": "Self-induced light emission in solid-state memristors replicates\n  neuronal biophotons: Key pre-synaptic and post-synaptic biological functions have been\nsuccessfully implemented in various hardware systems. A noticeable example are\nneuronal networks constructed from memristors, which are emulating complex\nelectro-chemical biological dynamics such a neuron's efficacy and plasticity.\nNeurons are highly active cells, communicating with chemical and electrical\nstimuli, but also emit light. These photons are suspected to be a complementary\nvehicle to transport information across the brain. Here, we show that a\nmemristor also releases photons akin to the production of neuronal light.\nCritical attributes of so-called biophotons such as self-generation, origin,\nstochasticity, spectral coverage, sparsity and correlation with the neuron's\nactivity are replicated by our solid-state approach. Our findings further\nextend the emulating capability of a memristor to encompass neuronal biophoton\nemission and open the possibility to construct a bimodal electro-optical\nplatform with the assistance of atomic-scale devices capable of handling\nelectrons and photons as information carriers."
    },
    {
        "anchor": "Spin diffusion in the Mn2+ ion system of II-VI diluted magnetic\n  semiconductor heterostructures: The magnetization dynamics in diluted magnetic semiconductor heterostructures\nbased on (Zn,Mn)Se and (Cd,Mn)Te has been studied experimentally by optical\nmethods and simulated numerically. In the samples with nonhomogeneous magnetic\nion distribution this dynamics is contributed by spin-lattice relaxation and\nspin diffusion in the Mn spin system. The spin diffusion coefficient of\n7x10^(-8) cm^2/s has been evaluated for Zn(0.99)Mn(0.01)Se from comparison of\nexperimental and numerical results. Calculations of the giant Zeeman splitting\nof the exciton states and the magnetization dynamics in the ordered alloys and\nparabolic quantum wells fabricated by the digital growth technique show perfect\nagreement with the experimental data. In both structure types the spin\ndiffusion has an essential contribution to the magnetization dynamics.",
        "positive": "Topological defects in a double-mirror quadrupole insulator displace\n  diverging charge: We show that topological defects in quadrupole insulators do not host\nquantized fractional charges, contrary to what their Wannier representation\nindicates. In particular, we test the charge quantization hypothesis based on\nthe Wannier representation of a parametric defect and a disclination. Against\nthe expectations, we find that the local charge density decays as $\\sim 1/r^2$\nwith distance, leading to a diverging defect charge. We identify sublattice\nsymmetry and not higher order topology as the origin of the previously reported\ncharge quantization."
    },
    {
        "anchor": "Photoinduced quantum spin and valley Hall effects and orbital\n  magnetization in monolayer MoS2: We theoretically demonstrate that 100\\% valley-polarized transport in\nmonolayers of MoS$_{2}$ and other group-VI dichalcogenides can be obtained\nusing off-resonant circularly polarized light. By tuning the intensity of the\noff-resonant light the intrinsic band gap in one valley is reduced, while it is\nenhanced in the other valley, enabling single valley quantum transport. As a\nconsequence, we predict (i) enhancement of the longitudinal electrical\nconductivity, accompanied by an increase in the spin-polarization of the\nflowing electrons, (ii) enhancement of the intrinsic spin Hall effect, together\nwith a reduction of the intrinsic valley Hall effect, and (iii) enhancement of\nthe orbital magnetic moment and orbital magnetization. These mechanisms provide\nappealing opportunities to the design of nanoelectronics based on\ndichalcogenides.",
        "positive": "Quantum quenches in a pseudo-Hermitian Chern insulator: We propose to uncover the topology of a pseudo-Hermitian Chern insulator by\nquantum quench dynamics. The Bloch Hamiltonian of the pseudo-Hermitian Chern\ninsulator is defined in the basis of the q-deformed Pauli matrices, which are\nrelated to the representation of the deformed algebras. We show the\nbulk-surface duality of the pseudo-Hermitian phases, then further build a\nconcrete relation between the static band topology and quench dynamics, in\nterms of the time-averaged spin textures. The results are also generalized into\na fully nonequilibrium case where the postquench evolution is governed by a\nFloquet pseudo-Hermitian Hamiltonian. Furthermore, we propose a possible scheme\nto realize the seemingly challenging model in a bilayer lattice and detect the\ndynamics with a double-quench protocol."
    },
    {
        "anchor": "Optical realization of magneto-intersubband oscillations: We report on the optical realization of the magneto-intersubband oscillations\nthat have been measured in the sub-terahertz transmittance of a GaAs quantum\nwell with two subbands occupied. Following their dc analogue, the oscillations\nare periodic in the inverse magnetic field with the period governed by the\nsubband gap. Their magnitude and polarization dependence accurately follow the\npresented simplified version of the dynamic magneto-intersubband oscillations\nequation that naturally combines dc magneto-intersabband oscillations with\nmicrowave-induced resistance oscillations (MIRO). Simultaneously measured\nphotoresistance also reveals its strong sensitivity to the sign of the circular\npolarization, proving the used theoretical modeling.",
        "positive": "Near-field three-terminal thermoelectric heat engine: We propose a near-field inelastic thermoelectric heat engine where\nquantum-dots are used to effectively rectify the charge flow of photo-carriers.\nThe device converts near-field heat radiation into useful electrical power.\nHeat absorption and inelastic transport can be enhanced by introducing two\ncontinuous spectra separated by an energy gap. The thermoelectric transport\nproperties of the heat engine are studied in the linear-response regime. Using\na small band-gap semiconductor as the absorption material, we show that the\ndevice achieves very large thermopower and thermoelectric figure-of-merit, as\nwell as considerable power-factor. By analyzing thermal-photo-carrier\ngeneration and conduction, we reveal that the Seebeck coefficient and the\nfigure of merit have oscillatory dependence on the thickness of the vacuum gap.\nMeanwhile, the power-factor, the charge and thermal conductivity are\nsignificantly improved by near-field radiation. Conditions and guiding\nprinciples for powerful and efficient thermoelectric heat engines are discussed\nin details."
    },
    {
        "anchor": "Carbyne: from the elusive allotrope to stable carbon atom wires: Besides graphite and diamond, the solid allotropes of carbon in sp2 and sp3\nhybridization, the possible existence of a third allotrope based on the\nsp-carbon linear chain, the Carbyne, has stimulated researchers for a long\ntime. The advent of fullerenes, nanotubes and graphene has opened new\nopportunities and nurtured the interest in novel carbon allotropes including\nlinear structures. The efforts made in this direction produced a number of\ninteresting sp-hybridized carbon molecules and nanostructures in the form of\ncarbon-atom wires. We here discuss some of the new perspectives opened by the\nrecent advancements in the research on sp-carbon systems.",
        "positive": "Majorana bound states in a superconducting Rashba nanowire in the\n  presence of antiferromagnetic order: Theoretical studies have shown that Majorana bound states can be induced at\nthe ends of a one dimensional wire, a phenomenon possible due to the interplay\nbetween s-wave superconductivity, spin-orbit coupling, and an external magnetic\nfield. These states have been observed in superconductor-semiconductor hybrid\nnanostructures in the presence of a Zeeman field, and in the limit of a low\ndensity of particles. In this paper, we demonstrate and discuss the possibility\nof the emergence of Majorana bound states in a superconducting Rashba nanowire\ndeposited on an antiferromagnetically ordered surface. We calculate the\nrelevant topological invariant in several complementary ways. Studying the\ntopological phase diagram reveals two branches of the non trivial topological\nphase -- a main branch, which is typical for Rashba nanowires, and an\nadditional branch emerging due to the antiferromagnetic order. In the case of\nthe additional topological branch, Majorana bound states can also exist close\nto half-filling, obviating the need for either doping or gating the nanowire to\nreach the low density regime. Moreover, we show the emergence of the Majorana\nbound states in the absence of the external magnetic field, which is possible\ndue to the antiferromagnetic order. We also discuss the properties of the bound\nstates in the context of real space localization and the spectral function of\nthe system. This allows one to perceive the band inversion within the spin and\nsublattice subspaces in the additional branch, contrary to the main branch,\nwhere the only band inversion reported in previous studies exists in the spin\nsubspace. Finally, we demonstrate how these topological phases can be confirmed\nexperimentally in transport measurements."
    },
    {
        "anchor": "Effect of Electron-RBM Phonon Interaction on Conductance of carbon\n  nanotubes: We use the energy analysis as a perturbative method to study the effect of\nelectron-radial breathing mode (RBM) phonon interaction on the electrical\nconductivity of long metallic zigzag carbon nanotubes (CNTs). The band\nstructure of zigzag CNTs is calculated by exerting zone-folding method on\nrelations derived by using the nearest neighbor approximation of tight-binding\nexpression for the $\\pi$ valence and conduction bands of graphene. The small\nhollow cylinder model, with two different approximations, is used to obtain the\nRBM frequency in our calculation. As the result, we have calculated the effects\nof electron$ - $RBM phonon interaction on the conductance of zigzag CNTs. It\nhas been observed that current is a step$ - $like function of bias voltage\nbecause of the absorption or emission by electron injection in the system.\nMoreover, the dependence of the conductance to the temperature in low bias and\nhigh bias voltages has been studied. In this paper, we propose a simple and\nuseful method for phonon spectroscopy. Also, since RBM mode determines the\ngeometry and structure of CNT, this approach can be used for characterization\nof CNTs.",
        "positive": "Influence of disordered edges on transport properties in graphene: The influence of plasma etched sample edges on electrical transport and\ndoping is studied. Through electrical transport measurements the overall doping\nand mobility are analyzed for mono- and bilayer graphene samples. As a result\nthe edge contributes strongly to the overall doping of the samples. Furthermore\nthe edge disorder can be found as the main limiting source of the mobility for\nnarrow samples."
    },
    {
        "anchor": "Angular Momentum of Phonons and Einstein-de Haas Effect: We study angular momentum of phonons in a magnetic crystal. In the presence\nof a spin-phonon interaction, we obtain a nonzero angular momentum of phonons,\nwhich is an odd function of magnetization. At zero temperature, phonon has a\nzero-point angular momentum besides a zero-point energy. With increasing\ntemperature, the total phonon angular momentum diminishes and approaches to\nzero in the classical limit. The nonzero phonon angular momentum can have a\nsignificant impact on the Einstein-de Haas effect. To obtain the change of\nangular momentum of electrons, the change of phonon angular momentum needs to\nbe subtracted from the opposite change of lattice angular momentum.\nFurthermore, the finding of phonon angular momentum gives a potential method to\nstudy the spin-phonon interaction. Possible experiments on phonon angular\nmomentum are also discussed.",
        "positive": "Pump driven normal-to-excitonic insulator transition: Josephson\n  oscillations and signatures of BEC-BCS crossover in time-resolved ARPES: We consider a ground-state wide-gap band insulator turning into a\nnonequilibrium excitonic insulator (NEQ-EI) upon visiting properly selected and\nphysically relevant highly excited states. The NEQ-EI phase, characterized by\nself-sustained oscillations of the complex order parameter, neatly follows from\na Nonequilibrium Green's Function treatment on the Konstantinov-Perel' contour.\nWe present the first {\\em ab initio} band structure of LiF, a ground-state bulk\ninsulator, in different NEQ-EI states and show that these states can be\ngenerated by currently available pump pulses. We highlight two general features\nof time-resolved ARPES spectra: (1) during the pump-driving the excitonic\nspectral structure undergoes a convex-to-concave shape transition and {\\em\nconcomitantly} the state of the system goes through a BEC-BCS crossover; (2)\nattosecond pulses shone after the pump-driving at different times $t_{\\rm\ndelay}$ generate a photocurrent which {\\em oscillates} in $t_{\\rm delay}$ with\na pump-tunable frequency -- we show that this phenomenon is similar to the AC\nresponse of an exotic Josephson junction."
    },
    {
        "anchor": "Quantum Manifestations of Graphene Edge Stress and Edge Instability: A\n  First-Principles Study: We have performed first-principles calculations of graphene edge stresses,\nwhich display two interesting quantum manifestations absent from the classical\ninterpretation: the armchair edge stress oscillates with a nanoribbon width,\nand the zigzag edge stress is noticeably reduced by spin polarization. Such\nquantum stress effects in turn manifest in mechanical edge twisting and warping\ninstability, showing features not captured by empirical potentials or continuum\ntheory. Edge adsorption of H and Stone-Wales reconstruction are shown to\nprovide alternative mechanisms in relieving the edge compression and hence to\nstabilize the planar edge structure.",
        "positive": "Parity switching in a full-shell superconductor-semiconductor nanowire\n  qubit: The rate of charge-parity switching in a full-shell\nsuperconductor-semiconductor nanowire qubit is measured by directly monitoring\nthe dispersive shift of a readout resonator. At zero magnetic field, the\nmeasured switching time scale $T_P$ is on the order of 100 ms. Two-tone\nspectroscopy data post-selected on charge-parity is demonstrated. With\nincreasing temperature or magnetic field, TP is at first constant, then\nexponentially suppressed, consistent with a model that includes both\nnon-equilibrium and thermally activated quasiparticles. As TP is suppressed,\nqubit lifetime T1 also decreases. The long $T_P\\sim 0.1$ s at zero field is\npromising for future development of qubits based on hybrid nanowires."
    },
    {
        "anchor": "Tunable Excitons in Rhombohedral Trilayer Graphene: Trilayer graphene is receiving an increasing level of attention due to its\nstacking--dependent magnetoelectric and optoelectric properties, and its more\nrobust ferromagnetism relative to monolayer and bilayer variants.\n  Additionally, rhombohedral stacked trilayer graphene presents the possibility\nof easily opening a gap via either an external electric field perpendicular to\nthe layers, or via the application of external strain.\n  In this paper, we consider an external electric field to open a bandgap in\nrhombohedral trilayer graphene and study the excitonic optical response of the\nsystem.\n  This is done via the combination of a tight binding model with the\nBethe--Salpeter equation, solved semi--analytically and requiring only a simple\nnumerical quadrature.\n  We then discuss the valley--dependent optical selection rules, followed by\nthe computation of the excitonic linear optical conductivity for the case of a\nrhombohedral graphene trilayer encapsulated in hexagonal boron nitride.\n  The tunability of the excitonic resonances via an external field is also\ndiscussed, together with the increasing localization of the excitonic states as\nthe field increases.",
        "positive": "Electrical conductance at initial stage in epitaxial growth of Pb on\n  modified Si(111) surface: The electrical conductance and RHEED intensities as a function of the\ncoverage have been measured during Pb depositions at 105 K on Si(111)-(6x6)Au\nwith up to 4.2 ML of annealed Pb. The experiments show the strong influence of\nused substrates on the behavior of the conductance during the epitaxy of Pb\natoms, especially for very initial stage of growth. Oscillations of the\nconductance during the layer-by-layer growth are correlated with RHEED\nintensity oscillations. The analysis of the conductance behavior is made\naccording to the theory described by Trivedi and Aschcroft (Phys.Rev.B 38,12298\n(1988))."
    },
    {
        "anchor": "The Jahn-Teller instability in dissipative quantum electromechanical\n  systems: We consider the steady states of a harmonic oscillator coupled so strongly to\na two-level system (a qubit) that the rotating wave approximation cannot be\nmade. The Hamiltonian version of this model is known as the $E\\otimes\\beta$\nJahn-Teller model. The semiclassical version of this system exhibits a fixed\npoint bifurcation, which in the quantum model leads to a ground state with\nsubstantial entanglement between the oscillator and the qubit. We show that the\ndynamical bifurcation survives in a dissipative quantum description of the\nsystem, amidst an even richer bifurcation structure. We propose two\nexperimental implementations of this model based on superconducting cavities: a\nparametrically driven nonlinear nanomechanical resonator coupled capacitively\nto a coplanar microwave cavity and a superconducting junction in the central\nconductor of a coplanar waveguide.",
        "positive": "Transport out of locally broken detailed balance: Electrons move along potential or thermal gradients. In the presence of a\nglobal gradient, applied e.g. to the two terminals of a conductor, this induces\nelectric charge and heat currents. They can also flow between two equilibrated\nterminals (at the same voltage and temperature) if detailed balance is broken\nin some part of the system. A minimal model involving two metallic islands in\nseries is introduced whose internal potential and temperatures can be\nexternally modulated. The conditions for a finite electric flow are discussed."
    },
    {
        "anchor": "Observation of extremely slow hole spin relaxation in self-assembled\n  quantum dots: We report the measurement of extremely slow hole spin relaxation dynamics in\nsmall ensembles of self-assembled InGaAs quantum dots. Individual spin\norientated holes are optically created in the lowest orbital state of each dot\nand read out after a defined storage time using spin memory devices. The\nresulting luminescence signal exhibits a pronounced polarization memory effect\nthat vanishes for long storage times. The hole spin relaxation dynamics are\nmeasured as a function of external magnetic field and lattice temperature. We\nshow that hole spin relaxation can occur over remarkably long timescales in\nstrongly confined quantum dots (up to ~270 us), as predicted by recent theory.\nOur findings are supported by calculations that reproduce both the observed\nmagnetic field and temperature dependencies. The results suggest that hole spin\nrelaxation in strongly confined quantum dots is due to spin orbit mediated\nphonon scattering between Zeeman levels, in marked contrast to higher\ndimensional nanostructures where it is limited by valence band mixing.",
        "positive": "Nonadiabatic pumping in classical and quantum chaotic scatterers: We study directed transport in periodically forced scattering systems in the\nregime of fast and strong driving where the dynamics is mixed to chaotic and\nadiabatic approximations do not apply. The model employed is a square potential\nwell undergoing lateral oscillations, alternatively as two- or single-parameter\ndriving. Mechanisms of directed transport are analyzed in terms of asymmetric\nirregular scattering processes. Quantizing the system in the framework of\nFloquet scattering theory, we calculate directed currents on basis of\ntransmission and reflection probabilities obtained by numerical wavepacket\nscattering. We observe classical as well as quantum transport beyond linear\nresponse, manifest in particular in a non-zero current for single-parameter\ndriving where according to adiabatic theory, it should vanish identically."
    },
    {
        "anchor": "Interplay between topology and localization on superconducting circuits: Topological insulator lie at the forefront of condensed matter physics.\nHowever strong disorder can destroy the topological states and make all states\nbecome localized. In this paper, we investigate the competition between\ntopology and localization in the one-dimensional Su-Schrieffer-Heeger (SSH)\nmodel with controllable off-diagonal quasi-periodic modulations on\nsuperconducting circuits. By utilizing external ac magnetic fluxes, each\ntransmon can be driven and all coupling strengths can be tuned independently.\nBased on this model we construct phase diagrams that illustrate the extended\ntopologically nontrivial, critical localization, and coexisting topological and\ncritical localization phases. The dynamics of the qubits' excitations are also\ndiscussed in this paper, revealing distinct quantum state transfers resulting\nfrom the interplay between topology and localization. Furthermore, we propose a\nmethod for detecting different quantum phases using current experimental\nsetups.",
        "positive": "Two-junction ballistic switch in quantum network model: Searching of optimal parameters of nanoelectronic devices is a primal problem\nin their modeling. We solve this problem on example of the electron ballistic\nswitch in quantum network model. For this purpose, we use a computing scheme in\nwhich closed channels are taking into account. It allows calculating correctly\na scattering matrix of the switch and, consequently, the electric currents\nflowing through it. Without losing generality, we consider model of\ntwo-junction switch at room temperature. Its character is localization of the\ncontrolling electric field in the domain before branching. We optimize switch\nparameters using a genetic algorithm. At the expense of it for InP, GaAs and\nGaSb switch efficiency reached 77-78%. It is established that, for the\nconsidered materials, volt-ampere characteristics of the device are close to\nthe linear ones at bias voltages 0-50 mV. It allowed describing with a good\naccuracy electron transport in the switch by means of $3\\times 3$ matrix of\napproximate conductivity. Finally, based on the performed parameters\noptimization of two-junction switch we formulate the general scheme of modeling\nnanoelectronic devices in the framework of quantum network formalism."
    },
    {
        "anchor": "Time-dependent density-matrix renormalization group: A systematic method\n  for the study of quantum many-body systems out-of-equilibrium: The density-matrix renormalization-group (DMRG) algorithm is extended to\ntreat time-dependent problems. The method provides a systematic and robust tool\nto explore out-of-equilibrium phenomena in quantum many-body systems. We\nillustrate the method by showing that attractive interactions enhance the\ntunneling current between two Luttinger liquids, whereas repulsive interactions\nsuppress it, in qualitative agreement with analytical predictions. Enhancement\nof the transport current through a quantum dot in the Kondo regime is also\nexhibited.",
        "positive": "Electrical transport in two dimensional electron and hole gas on\n  Si(001)-(2x1) surface: Si(001)-(2$\\times$1) surface is one of the many two-dimensional systems of\nscientific and applied interest. It has two surface state bands (1)\nanti-bonding pi* band, which has acceptor states and (2) bonding pi band, which\nhas donor states. Due to its asymmetric dimer reconstruction, transport through\nthis surface can be considered in two distinct directions, i.e. along and\nperpendicular to the paired dimer rows. We calculate the zero bias conductance\nof these surface states under flat-band condition and find that conduction\nalong the dimer row direction is significant due to strong orbital\nhybridization. We also find that the surface conductance is orders of magnitude\nhigher than the bulk conductance close to the band edges for the unpassivated\nsurface at room temperature. Therefore, we propose that the transport through\nthese surface states may be the dominant conduction mechanisms in the recently\nreported scanning tunneling microscopy of silicon nanomembranes. We also\ncalculate the zero bias conductance under flat-band condition for the weakly\ninteracting dangling bond wires along and perpendicular to the dimer row\ndirection and find similar trends. Extended Huckel theory is used for the\nelectronic structure calculations, which is benchmarked with the GW\napproximation for Si and has been successfully applied to Si systems in past."
    },
    {
        "anchor": "Magnetic Behaviour of Assemblies of Interacting Cobalt-Carbide\n  Nanoparticles: Recent work [1] demonstrated high coercivity and magnetic moment in cobalt\ncarbide nanoparticle assemblies and explained the high coercivity from first\nprinciples in terms of the high magnetocrystalline anisotropy of the cobalt\ncarbide nanoparticles. In this work, we comprehensively model the interaction\nbetween the nanoparticles comprising the assembly and systematically understand\nthe effect of particle size, distribution of the orientations of the\nnanoparticles' magnetocrystalline anisotropy axis with respect to the applied\nmagnetic field, and dipole coupling between nanoparticles on the temperature\ndependent magnetic behavior of the nanoparticle assembly. We show that\nmagnetocrystalline anisotropy alone is not enough to explain the large\nhysteresis over the 50K-400K temperature range and suggest that defects and\ninhomogeneties that pin the magnetization could also play a significant role on\nthis temperature dependent magnetic behavior.",
        "positive": "Topological transition of Dirac points in a microwave experiment: By means of a microwave tight-binding analogue experiment of a graphene-like\nlattice, we observe a topological transition between a phase with a point-like\nband gap characteristic of massless Dirac fermions and a gapped phase. By\napplying a controlled anisotropy on the structure, we investigate the\ntransition directly via density of states measurements. The wave function\nassociated with each eigenvalue is mapped and reveals new states at the Dirac\npoint, localized on the armchair edges. We find that with increasing\nanisotropy, these new states are more and more localized at the edges."
    },
    {
        "anchor": "Optical properties and single-electron states of the nanosystem that\n  contains three quantum dots: The quantum molecule consisting of three quantum dots that forms a triangle\nwith its centers is studied. The electron wave function in the nanosystem is\nwritten using the linear combination of orbital quantum wells. The dispersion\nequation for numerical calculations of the electron stationary states in a\nquantum molecule is found. A numerical calculation of the electron energy\nspectrum in the molecule formed by three quantum dots of a spherical shape is\ncarried out. The influence of the nanocrystal size, the distance between them\nand the symmetry of the quantum molecule on the electron energy spectrum is\nstudied. The cases of symmetry of an equilateral and an isosceles triangle are\nconsidered.",
        "positive": "The influence of constriction on the motion of graphene kinks: Graphene kinks are topological states of buckled graphene membranes. We show\nthat when a moving kink encounters a constriction, there are three general\nclasses of behavior: reflection, trapping, and transmission. Overall,\nconstriction is characterized by an attractive potential. In the case of a\nsimple symmetric constriction, the kink potential energy has a relatively deep\nminimum surrounded by energy barriers. However, the potential energy alone does\nnot fully define the class of behavior: the effect of a resonant reflection was\nobserved in our simulations. Moreover, we demonstrate that asymmetric\nconstrictions can transform kinks from one type into another. MD simulation\nresults are compared with predictions of the classical $\\phi^4$ model."
    },
    {
        "anchor": "Temperature dependent equilibration of spin orthogonal quantum Hall edge\n  modes: Conductance of the edge modes as well as conductance across the\nco-propagating edge modes around the \\nu = 4/3, 5/3 and 2 quantum Hall states\nare measured by individually exciting the modes. Temperature dependent\nequilibration rates of the outer unity conductance edge mode are presented for\ndifferent filling fractions. We find that the equilibration rate of the outer\nunity conductance mode at \\nu = 2 is higher and more temperature sensitive\ncompared to the mode at fractional filling 5/3 and 4/3. At lowest temperature,\nequilibration length of the outer unity conductance mode tends to saturate with\nlowering filling fraction \\nu by increasing magnetic field B. We speculate this\nsaturating nature of equilibration length is arising from an interplay of\nCoulomb correlation and spin orthogonality.",
        "positive": "Transport through single-level systems: Spin dynamics in the\n  nonadiabatic regime: We investigate the Fano-Anderson model coupled to a large ensemble of spins\nunder the influence of an external magnetic field. The interaction between the\ntwo spin systems is treated within a meanfield-approach and we assume an\nanisotropic coupling between these two systems. By using a nonadiabatic\napproach, we make no further approximations in the theoretical description of\nour system, apart from the semiclassical treatment. Therewith, we can include\nthe short-time dynamics as well as the broadening of the energy levels arising\ndue to the coupling to the external electronic reservoirs. We study the spin\ndynamics in the regime of low and high bias. For the infinite bias case, we\ncompare our results to those obtained from a simpler rate equation approach,\nwhere higher-order transitions are neglected. We show, that these higher-order\nterms are important in the range of low magnetic field. Additionally, we\nanalyze extensively the finite bias regime with methods from nonlinear\ndynamics, and we discuss the possibility of switching of the large spin."
    },
    {
        "anchor": "Chiral symmetry and its manifestation in optical responses in graphene:\n  interaction and multi-layers: Chiral symmetry, fundamental in the physics of graphene, guarantees the\nexistence of topologically stable doubled Dirac cones and anomalous behaviors\nof the zero-energy Landau level in magnetic fields. The crucial role is\ninherited in the optical responses and many-body physics in graphene, which are\nexplained in this paper. We also give an overview of multilayer graphene from\nthe viewpoint of the optical properties and their relation with the chiral\nsymmetry.",
        "positive": "ReS2/h-BN/Graphene Heterostructure Based Multifunctional Devices:\n  Tunnelling Diodes, FETs, Logic Gates & Memory: We investigate a two-dimensional (2D) heterostructure consisting of few-layer\ndirect bandgap ReS2, a thin h-BN layer and a monolayer graphene for application\nto various electronic devices. Metal-insulator-semiconductor (MIS)-type devices\nwith two-dimensional (2D) van-der-Waals (vdW) heterostructures have recently\nbeen studied as important components to realize various multifunctional device\napplications in analogue and digital electronics. The tunnel diodes of\nReS2/h-BN/graphene exhibit light tuneable rectifying behaviours with low\nideality factors and nearly temperature independent electrical characteristics.\nThe devices behave like conventional MIS-type tunnel diodes for logic gate\napplications. Furthermore, similar vertical heterostructures are shown to\noperate in field effect transistors with a low threshold voltage and a memory\ndevice with a large memory gate for future multifunctional device applications."
    },
    {
        "anchor": "98% directional guiding of spin currents with 90 micrometer relaxation\n  length in bilayer graphene using carrier drift: Electrical control of spin signals and long distance spin transport are major\nrequirements in the field of spin electronics. Here we report the efficient\nguiding of spin currents at room temperature in high mobility hexagonal boron\nnitride encapsulated bilayer graphene using carrier drift. Our experiments,\ntogether with modelling, show that the spin relaxation length can be tuned from\n2 to 88 micrometers when applying a DC current of $\\mp$40 uA respectively. Our\nmodel predicts that, extending the range up to $\\mathrm{I_{dc}}=\\mp$150 uA, the\nspin relaxation length can be tuned from 0.6 to 320 um respectively, indicating\nthat spin relaxation lengths in the millimeter range are within scope in near\nfuture with moderate current densities. Our results also show that we are able\nto direct spin currents on either side of a spin injection contact. 98% of the\ninjected spins flow to the left when $\\mathrm{I_{dc}}$= -40 uA and 65% flow to\nthe right when the drift current is reversed. Our model shows that, for\n$\\mathrm{I_{dc}}=\\mp$150 uA the numbers reach 99.8% and 95% respectively\nshowing the potential of carrier drift for spin-based logic operations and\ndevices.",
        "positive": "Direct detection of magnon spin transport by the inverse spin Hall\n  effect: Conversion of traveling magnons into an electron carried spin current is\ndemonstrated in a time resolved experiment using a spatially separated\ninductive spin-wave source and an inverse spin Hall effect (ISHE) detector. A\nshort spin-wave packet is excited in a yttrium-iron garnet (YIG) waveguide by a\nmicrowave signal and is detected at a distance of 3 mm by an attached Pt layer\nas a delayed ISHE voltage pulse. The delay in the detection appears due to the\nfinite spin-wave group velocity and proves the magnon spin transport. The\nexperiment suggests utilization of spin waves for the information transfer over\nmacroscopic distances in spintronic devices and circuits."
    },
    {
        "anchor": "Structurally-driven magnetic state transition of biatomic Fe chains on\n  Ir(001): Using first-principles calculations, we demonstrate that the magnetic\nexchange interaction and the magnetocrystalline anisotropy of biatomic Fe\nchains grown in the trenches of the 5x1 reconstructed Ir(001) surface depend\nsensitively on the atomic arrangement of the Fe atoms. Two structural\nconfigurations have been considered which are suggested from recent\nexperiments. They differ by the local symmetry and the spacing between the two\nstrands of the biatomic Fe chain. Since both configurations are very close in\ntotal energy they may coexist in experiment. We have investigated collinear\nferro- and antiferromagnetic solutions as well as a collinear state with two\nmoments in one direction and one in the opposite direction (up-down-up-state).\nFor the structure with a small interchain spacing, there is a strong exchange\ninteraction between the strands and the ferromagnetic state is energetically\nfavorable. In the structure with larger spacing, the two strands are\nmagnetically nearly decoupled and exhibit antiferromagnetic order along the\nchain. In both cases, due to hybridization with the Ir substrate the exchange\ninteraction along the chain axis is relatively small compared to freestanding\nbiatomic iron chains. The easy magnetization axis of the Fe chains also\nswitches with the structural configuration and is out-of-plane for the\nferromagnetic chains with small spacing and along the chain axis for the\nantiferromagnetic chains with large spacing between the two strands. Calculated\nscanning tunneling microscopy images and spectra suggest the possibility to\nexperimentally distinguish between the two structural and magnetic\nconfigurations.",
        "positive": "Steplike electric conduction in a classical two-dimensional electron\n  system through a narrow constriction in a microchannel: Using molecular dynamics simulation, we investigate transport properties of a\nclassical two-dimensional electron system confined in a microchannel with a\nnarrow constriction. As a function of the confinement strength of the\nconstriction, the calculated conductance in the simulations exhibits steplike\nincreases as reported in a recent experiment [D. G. Rees et al., Phys. Rev.\nLett. 106, 026803 (2011)]. It is confirmed that the number of the steps\ncorresponds to the number of stream lines of electrons through the\nconstriction. We verify that density fluctuation plays a major role in\nsmoothing the steps in the conductance."
    },
    {
        "anchor": "Electromagnetic response and pseudo-zero-mode Landau levels of bilayer\n  graphene in a magnetic field: The electromagnetic response of bilayer graphene in a magnetic field is\nstudied in comparison with that of monolayer graphene. Both types of graphene\nturn out to be qualitatively quite similar in dielectric and screening\ncharacteristics, especially those deriving from vacuum fluctuations, but the\neffect is generally much more sizable for bilayers. The presence of the\nzero-(energy-)mode Landau levels is a feature specific to graphene. In\nbilayers, unlike in monolayers, the effect of the zero-mode levels becomes\nvisible and even dominant in density response as an externally-controllable\nband gap develops. It is pointed out that the splitting of nearly-degenerate\npseudo-zero-mode levels at each valley, specific to bilayer graphene, is\ncontrolled by an applied inplane electric field or by an injected current. In\naddition, a low-energy effective gauge theory of bilayer graphene is\nconstructed.",
        "positive": "Giant spin Nernst effect in a two-dimensional antiferromagnet due to\n  magnetoelastic coupling-induced gaps and interband transitions between\n  magnon-like bands: We analyze theoretically the origin of the spin Nernst and thermal Hall\neffects in FePS3 as a realization of two-dimensional antiferromagnet (2D AFM).\nWe find that a strong magnetoelastic coupling, hybridizing magnetic excitation\n(magnon) and elastic excitation (phonon), combined with\ntime-reversal-symmetry-breaking, results in a Berry curvature hotspots in the\nregion of anticrossing between the two distinct hybridized bands. Furthermore,\nlarge spin Berry curvature emerges due to interband transitions between two\nmagnon-like bands, where a small energy gap is induced by magnetoelastic\ncoupling between such bands that are energetically distant from anticrossing of\nhybridized bands. These nonzero Berry curvatures generate topological\ntransverse transport (i.e., the thermal Hall effect) of hybrid excitations,\ndubbed magnon-polaron, as well as of spin (i.e., the spin Nernst effect)\ncarried by them, in response to applied longitudinal temperature gradient. We\ninvestigate the dependence of the spin Nernst and thermal Hall conductivities\non the applied magnetic field and temperature, unveiling very large spin Nernst\nconductivity even at zero magnetic field. Our results suggest FePS3 AFM, which\nis already available in 2D form experimentally, as a promising platform to\nexplore the topological transport of the magnon-polaron quasiparticles at THz\nfrequencies."
    },
    {
        "anchor": "Coupling emission from single localized defects in 2D semiconductor to\n  surface plasmon polaritons: Coupling of an atom-like emitter to surface plasmons provides a path toward\nsignificant optical nonlinearity, which is essential in quantum information\nprocessing and quantum networks. A large coupling strength requires\nnanometer-scale positioning accuracy of the emitter near the surface of the\nplasmonic structure, which is challenging. We demonstrate the coupling of\nsingle localized defects in a tungsten diselenide (WSe2) monolayer self-aligned\nto the surface plasmon mode of a silver nanowire. The silver nanowire induces a\nstrain gradient on the monolayer at the overlapping area, leading to the\nformation of localized defect emission sites that are intrinsically close to\nthe surface plasmon. We measure a coupling efficiency with a lower bound of 39%\nfrom the emitter into the plasmonic mode of the silver nanowire. This technique\noffers a way to achieve efficient coupling between plasmonic structures and\nlocalized defects of 2D semiconductors.",
        "positive": "Resonance Absorption of Terahertz Radiation in Nanoperforated Graphene: Recent measurements of the conductivity of nanoperforated graphene are\ninterpreted in terms of edges states existing near the edge of each nanohole.\nThe perimetric quantization of edge states should result in the formation of a\nquasi-equidistant ladder of quasistationary energy levels. Dirac fermions\nfilling this ladder rotate about each nanohole in the direction determined by\nthe valley index. It is shown that the irradiation of this system by circularly\npolarized terahertz radiation leads to a resonance in absorption in one of the\nvalleys. The magnitude of absorption at the resonance frequency can be\ncontrolled by means of gate voltage."
    },
    {
        "anchor": "Feedback control of a solid-state qubit using high-fidelity projective\n  measurement: We demonstrate feedback control of a superconducting transmon qubit using\ndiscrete, projective measurement and conditional coherent driving. Feedback\nrealizes a fast and deterministic qubit reset to a target state with 2.4% error\naveraged over input superposition states, and cooling of the transmon from 16%\nspurious excitation to 3%. This closed-loop qubit control is necessary for\nmeasurement-based protocols such as quantum error correction and teleportation.",
        "positive": "Time Dependent Study of Multiple Exciton Generation in Nanocrystal\n  Quantum Dots: We study the exciton dynamics in an optically excited nanocrystal quantum\ndot. Multiple exciton formation is more efficient in nanocrystal quantum dots\ncompared to bulk semiconductors due to enhanced Coulomb interactions and the\nabsence of conservation of momentum. The formation of multiple excitons is\ndependent on different excitation parameters and the dissipation. We study this\nprocess within a Lindblad quantum rate equation using the full many-particle\nstates. We optically excite the system by creating a single high energy exciton\n$E_{SX}$ in resonance to a double exciton $E_{DX}$. With Coulomb\nelectron-electron interaction, the population can be transferred from the\nsingle exciton to the double exciton state by impact ionisation (inverse Auger\nprocess). The ratio between the recombination processes and the absorbed\nphotons provide the yield of the structure. We observe a quantum yield of\ncomparable value to experiment assuming typical experimental conditions for a\n$4$ nm PbS quantum dot."
    },
    {
        "anchor": "Intrinsic anomalous Hall effect arising from antiferromagnetic structure\n  revealed by high-quality NbMnP: The large anomalous Hall effect (AHE) in antiferromagnetic (AF) materials\narises from symmetry breaking equivalent to a ferromagnetic (FM) state.\nConsequently, this suggests that the observed AHE is induced by the intrinsic\nmechanism of the band structure effect, which in turn induces dissipationless\ntransverse conductivity. Confirmation of impurity-insensitive anomalous Hall\nconductivity (AHC) is crucial to conclude this interpretation; however,\nexperimental investigations in AF materials are limited by the lack of high\nquality systems. In this study, we show that the AF material NbMnP, which\nexhibits a large AHE, offers a high quality single crystal. Our findings\nclearly revealed that the large AHC and the tiny net magnetization of\n$\\sim10^{-3} \\mu_{\\mathrm{B}}$/Mn are inherent in this material, irrespective\nof disorder. NbMnP is a novel AF material that generates FM responses in the\nregime where there is less impurity scattering.",
        "positive": "Landau polaritons in highly non-parabolic 2D gases in the ultra-strong\n  coupling regime: We probe ultra-strong light matter coupling between metallic terahertz\nmetasurfaces and Landau-level transitions in high mobility 2D electron and hole\ngases. We utilize heavy-hole cyclotron resonances in strained Ge and electron\ncyclotron resonances in InSb quantum wells, both within highly non-parabolic\nbands, and compare our results to well known parabolic AlGaAs/GaAs quantum well\n(QW) systems. Tuning the coupling strength of the system by two methods,\nlithographically and by optical pumping, we observe a novel behavior clearly\ndeviating from the standard Hopfield model previously verified in cavity\nquantum electrodynamics: an opening of a lower polaritonic gap."
    },
    {
        "anchor": "Spin-orbit effects on the Larmor dispersion relation in GaAs quantum\n  wells: We have studied the relevance of spin-orbit coupling to the dispersion 00009\nrelation of the Larmor resonance observed in inelastic light scattering and\nelectron-spin resonance experiments on GaAs quantum wells. We show that the\nspin-orbit interaction, here described by a sum of Dresselhaus and\nBychkov-Rashba terms, couples Zeeman and spin-density excitations. We have\nevaluated its contribution to the spin splitting as a function of the magnetic\nfield $B$, and have found that in the small $B$ limit, the spin-orbit\ninteraction does not contribute to the spin splitting, whereas at high magnetic\nfields it yields a $B$ independent contribution to the spin splitting given by\n$2(\\lambda_R^2-\\lambda_D^2)$, with $\\lambda_{R,D}$ being the intensity of the\nBychkov-Rashba and Dresselhaus spin-orbit terms.",
        "positive": "The magnetism of wurtzite CoO nanoclusters: The possibility that the apparent room temperature ferromagnetism, often\nmeasured in Co-doped ZnO, is due to uncompensated spins at the surface of\nwurtzite CoO nanoclusters is investigated by means of a combination of density\nfunctional theory and Monte Carlo simulations. We find that the critical\ntemperature extracted from the specific heat systematically drops as the\ncluster size is reduced, regardless of the particular cluster shape.\nFurthermore the presence of defects, in the form of missing magnetic sites,\nfurther reduces $T_\\mathrm{C}$. This suggests that even a spinodal decomposed\nphase is unlikely to sustain room temperature ferromagnetism in ZnO:Co."
    },
    {
        "anchor": "Non-vanishing spin Hall currents in disordered spin-orbit coupling\n  systems: Spin currents that flow perpendicular to the electric field direction are\ngeneric in metals and doped semiconductors with spin-orbit coupling. It has\nrecently been argued that the spin Hall conductivity can be dominated by an\nintrinsic contribution which follows from Bloch state distortion in the\npresence of an electric field. Here we report on an numerical demonstration of\nthe robustness of this effect in the presence of disorder scattering for the\ncase of a two-dimensional electron-gas with Rashba spin-orbit interactions\n(R2DES).",
        "positive": "Manipulation of magnetization and spin transport in hydrogenated\n  graphene with THz pulses: Terahertz (THz) field pulses can now be applied in Scanning Tunnelling\nMicroscopy (THz-STM) junction experiments to study time resolved dynamics. The\nrelatively slow pulse compared to the typical electronic time-scale calls for\napproximations based on a time-scale separation. Here, we contrast three\nmethods based on non-equilibrium Green's functions (NEGF): (i) the\nsteady-state, adiabatic results, (ii) the lowest order dynamic expansion in the\ntime-variation (DE), and (iii) the auxiliary mode (AM) propagation method\nwithout approximations in the time-variation. We consider a concrete THz-STM\njunction setup involving a hydrogen adsorbate on graphene where the localized\nspin polarization can be manipulated on/off by a local field from the tip\nelectrode and/or a back-gate affecting the in-plane transport. We use\nsteady-state NEGF combined with Density Functional Theory (DFT-NEGF) to obtain\na Hubbard model for the study of the junction dynamics. Solving the Hubbard\nmodel in a mean-field approximation, we find that the near-adiabatic first\norder dynamical expansion provides a good description for STM voltage pulses up\nto the 1 V range."
    },
    {
        "anchor": "Quantum-classical correspondence in the wavefunctions of Andreev\n  billiards: We present a classical and quantum mechanical study of an Andreev billiard\nwith a chaotic normal dot. We demonstrate that in general the classical\ndynamics of these normal-superconductor hybrid systems is mixed, thereby\nindicating the limitations of a widely used retracing approximation. We show\nthat the mixed classical dynamics gives rise to a wealth of wavefunction\nphenomena, including periodic orbit scarring and localization of the\nwavefunction onto other classical phase space objects such as intermittent\nregions and quantized tori.",
        "positive": "Observation of pinning mode in Wigner solid of 1/3 fractional quantum\n  Hall excitations: We report the observation of a resonance in the microwave spectra of the real\ndiagonal conductivities of a two-dimensional electron system within a range of\n~ +- .0.015 $ from filling factor $\\nu=1/3$. The resonance is remarkably\nsimilar to resonances previously observed near integer $\\nu$, and is\ninterpreted as the collective pinning mode of a disorder-pinned Wigner solid\nphase of $e/3$-charged carriers ."
    },
    {
        "anchor": "Imaging magnetoelectric subbands in ballistic constrictions: We perform scanning gate experiments on ballistic constrictions in the\npresence of small perpendicular magnetic fields. The constrictions form the\nentrance and exit of a circular gate-defined ballistic stadium. Close to\nconstrictions we observe sets of regular fringes creating a checker board\npattern. Inside the stadium conductance fluctuations governed by chaotic\ndynamics of electrons are visible. The checker board pattern allows us to\ndetermine the number of transmitted modes in the constrictions forming between\nthe tip-induced potential and gate-defined geometry. Spatial investigation of\nthe fringe pattern in a perpendicular magnetic field shows a transition from\nelectrostatic to magnetic depopulation of magnetoelectric subbands. Classical\nand quantum simulations agree well with different aspects of our observations.",
        "positive": "Electron-induced rippling in graphene: We show that the interaction between flexural phonons, when corrected by the\nexchange of electron-hole excitations, may place the graphene sheet very close\nto a quantum critical point characterized by the strong suppression of the\nbending rigidity of the membrane. Ripples arise then due to spontaneous\nsymmetry breaking, following a mechanism similar to that responsible for the\ncondensation of the Higgs field in relativistic field theories. In the presence\nof membrane tensions, ripple condensation may be reinforced or suppressed\ndepending on the sign of the tension, following a zero-temperature buckling\ntransition in which the order parameter is given essentially by the square of\nthe gradient of the flexural phonon field."
    },
    {
        "anchor": "Electrical Current from Quantum Vacuum Fluctuations in Nano-engines: We theoretically investigate a quantum dot coupled to fermionic (electronic)\nleads and show how zero-point quantum fluctuations stemming from bosonic\nenvironments permit the rectification of the current. The bosonic baths are\neither external impedances modeled as tunable transmission lines or LC\nresonators (single-mode cavities). Voltage fluctuations stemming from the\nexternal impedances at zero temperature are described through harmonic\noscillators (photon-like excitations) then producing the quantum vacuum\nfluctuations. The differing sizes of the zero-point fluctuations of the quantum\nvacuum break the spatial symmetry of the system if the quantum dot is coupled\nto two reservoirs or two junctions with different bosonic environments. We\nconsider current rectification and power production when the system is operated\nas a heat engine in both non-resonant and resonant sequential tunneling cases.",
        "positive": "Raman vibrational spectra of bulk to monolayer ReS2 with lower symmetry: Lattice structure and symmetry of two-dimensional (2D) layered materials are\nof key importance to their fundamental mechanical, thermal, electronic and\noptical properties. Raman spectroscopy, as a convenient and nondestructive\ntool, however has its limitations on identifying all symmetry allowing Raman\nmodes and determining the corresponding crystal structure of 2D layered\nmaterials with high symmetry like graphene and MoS2. Due to lower structural\nsymmetry and extraordinary weak interlayer coupling of ReS2, we successfully\nidentified all 18 first-order Raman active modes for bulk and monolayer ReS2.\nWithout van der Waals (vdW) correction, our local density approximation (LDA)\ncalculations successfully reproduce all the Raman modes. Our calculations also\nsuggest no surface reconstruction effect and the absence of low frequency\nrigid-layer Raman modes below 100 cm-1. Combining with Raman and LDA thus\nprovides a general approach for studying the vibrational and structural\nproperties of 2D layered materials with lower symmetry."
    },
    {
        "anchor": "Excitations in a superconducting Coulombic energy gap: Cooper pairing and Coulomb repulsion are antagonists, producing distinct\nenergy gaps in superconductors and Mott insulators. When a superconductor\nexchanges unpaired electrons with a quantum dot, its gap is populated by a pair\nof electron-hole symmetric Yu-Shiba-Rusinov excitations between doublet and\nsinglet many-body states. The fate of these excitations in the presence of a\nstrong Coulomb repulsion in the superconductor is unknown, but of importance in\napplications such as topological superconducting qubits and multi-channel\nimpurity models. Here we couple a quantum dot to a superconducting island with\na tunable Coulomb repulsion. We show that a strong Coulomb repulsion changes\nthe singlet many-body state into a two-body state. It also breaks the\nelectron-hole energy symmetry of the excitations, which thereby lose their\nYu-Shiba-Rusinov character.",
        "positive": "Exciton Superposition across Moir\u00e9 States in a Semiconducting Moir\u00e9\n  Superlattice: Moir\\'e superlattices of semiconducting transition metal dichalcogenides\n(TMDCs) enable unprecedented spatial control of electron wavefunctions in an\nartificial lattice with periodicities more than ten times larger than that of\natomic crystals, leading to emerging quantum states with fascinating electronic\nand optical properties. The breaking of translational symmetry further\nintroduces a new degree of freedom inside each moir\\'e unit cell: high symmetry\npoints of energy minima called moir\\'e sites, behaving as spatially separated\nquantum dots. The superposition of a quasiparticle wavefunction between\ndifferent moir\\'e sites will enable a new platform for quantum information\nprocessing but is hindered by the suppressed electron tunneling between moir\\'e\nsites. Here we demonstrate the superposition between two moir\\'e sites by\nconstructing an angle-aligned trilayer WSe2/monolayer WS2 moir\\'e\nheterojunction. The two moir\\'e sites with energy minimum allow the formation\nof two different interlayer excitons, with the hole residing in either moir\\'e\nsite of the first WSe2 layer interfacing the WS2 layer and the electron in the\nthird WSe2 layer. An external electric field can drive the hybridization of\neither of the interlayer excitons with the intralayer excitons in the third\nWSe2 layer, realizing the continuous tuning of interlayer exciton hopping\nbetween two moir\\'e sites. Therefore, a superposition of the two interlayer\nexcitons localized at different moir\\'e sites can be realized, which can be\nresolved in the electric-field-dependent optical reflectance spectra,\ndistinctly different from that of the natural trilayer WSe2 in which the\nmoir\\'e modulation is absent. Our study illustrates a strategy of harnessing\nthe new moir\\'e site degree of freedom for quantum information science, a new\ndirection of twistronics."
    },
    {
        "anchor": "Molecular states observed in a single pair of strongly coupled\n  self-assembled InAs quantum dots: Molecular states in a SINGLE PAIR of strongly coupled self-assembled InAs\nquantum dots are investigated using a sub-micron sized single electron\ntransistor containing just a few pairs of coupled InAs dots embedded in a GaAs\nmatrix. We observe a series of well-formed Coulomb diamonds with charging\nenergy of less than 5 meV, which are much smaller than those reported\npreviously. This is because electrons are occupied in molecular states, which\nare spread over both dots and occupy a large volume. In the measurement of\nground and excited state single electron transport spectra with magnetic field,\nwe find that the electrons are sequentially trapped in symmetric and\nanti-symmetric states. This result is well-explained by numerical calculation\nusing an exact diagonalization method.",
        "positive": "Path Integral Representation for Composite Fermions and Bosons: The density matrix of the 2D system of spinless electrons confined to the\nlowest Landau level is expressed using both basis of states parametrized by\nelectron locations and basis of states parametrized by hole locations. In this\nrepresentation, the electron-electron repulsion can be viewed as an\nelectron-hole attraction. Electron-hole pairs stabilized by this attraction\nprovide a new formulation for Composite Fermions which fully respects\nparticle-hole symmetry. This representation also allows a particularly simple\nformulation of the composite Boson approach of generic n =p/q incompressible\nstates: The n =p/q state corresponds to the formation of clusters made up on p\nelectrons and q-p holes and fractionally charged excitations correspond to the\nbreaking of such clusters."
    },
    {
        "anchor": "Formation of Strain-Induced Quantum Dots in Gated Semiconductor\n  Nanostructures: Elastic strain changes the energies of the conduction band in a\nsemiconductor, which will affect transport through a semiconductor\nnanostructure. We show that the typical strains in a semiconductor\nnanostructure from metal gates are large enough to create strain-induced\nquantum dots (QDs). We simulate a commonly used QD device architecture, metal\ngates on bulk silicon, and show the formation of strain-induced QDs. The\nstrain-induced QD can be eliminated by replacing the metal gates with\npoly-silicon gates. Thus strain can be as important as electrostatics to QD\ndevice operation operation.",
        "positive": "Viscoelastic response and anisotropic hydrodynamics in Weyl semimetals: We study viscoelastic response in Weyl semimetals with broken time-reversal\nsymmetry. Topology and anisotropy of the Fermi surface are manifested in the\nviscoelasticity tensor of the electron fluid. In the dynamic (inter-band) part\nof this tensor, the anisotropy leads to a qualitatively different, compared to\nisotropic models, scaling with frequency and the Fermi energy. While components\nof the viscosity tensor determined by the Fermi surface properties agree in the\nKubo and kinetic formalisms, the latter misses the anomalous Hall viscosity\ndetermined by filled states below the Fermi surface. The anisotropy of the\ndispersion relation is also manifested in the acceleration and relaxation terms\nof the hydrodynamic equations."
    },
    {
        "anchor": "Superconducting Nanocircuits for Topologically Protected Qubits: For successful realization of a quantum computer, its building blocks\n(qubits) should be simultaneously scalable and sufficiently protected from\nenvironmental noise. Recently, a novel approach to the protection of\nsuperconducting qubits has been proposed. The idea is to prevent errors at the\n\"hardware\" level, by building a fault-free (topologically protected) logical\nqubit from \"faulty\" physical qubits with properly engineered interactions\nbetween them. It has been predicted that the decoupling of a protected logical\nqubit from local noises would grow exponentially with the number of physical\nqubits. Here we report on the proof-of-concept experiments with a prototype\ndevice which consists of twelve physical qubits made of nanoscale Josephson\njunctions. We observed that due to properly tuned quantum fluctuations, this\nqubit is protected against magnetic flux variations well beyond linear order,\nin agreement with theoretical predictions. These results demonstrate the\nfeasibility of topologically protected superconducting qubits.",
        "positive": "The Effect of Disorder in Superfluid Double Layer Graphene: We investigate the superfluid properties of disordered double layer graphene\nsystems using the non-equilibrium Green's function (NEGF) formalism. The\ncomplexity of such a structure makes it imperative to study the effects of\nlattice vacancies which will inevitably arise during fabrication. We present\nand compare room temperature performance characteristics for both ideal and\ndisordered bilayer graphene systems in an effort to illustrate the behavior of\na Bose-Einstein Condensate in the presence of lattice defects under\nnon-equilibrium conditions. We find that lattice vacancies spread throughout\nthe top layer past the coherence length have a reduced effect compared to the\nideal case. However, vacancies concentrated near the metal contacts within the\ncoherence length significantly alter the interlayer superfluid transport\nproperties."
    },
    {
        "anchor": "Observation of $h/e$ conductance oscillations in disordered metallic\n  $T_3$ network: We report on magnetotransport measurements performed on a large metallic\ntwo-dimensional $\\mathcal{T}_{3}$ network. Superimposed on the conventional\nAltshuler-Aronov-Spivak (AAS) oscillations of period $h/2e$, we observe clear\n$h/e$ oscillations in magnetic fields up to $8 T$. Different interpretations of\nthis phenomenon are proposed.",
        "positive": "Counting statistics of charge pumping in an open system: Electron counting statistics of a current pump in an open system has\nuniversal form in the weak pumping current regime. In the time domain, charge\ntransmission is described by two uncorrelated Poisson processes, corresponding\nto electron transmission in the right and left direction. Overall noise is\nsuper-poissonian, and can be reduced to poissonian by tuning the amplitude and\nphase of driving signal so that current to noise ratio is maximized. Measuring\nnoise in this regime provides a new method for determining charge quantum in an\nopen system without any fitting parameters."
    },
    {
        "anchor": "Modelling of Current Percolation Channels in Emerging Resistive\n  Switching Elements: Metallic oxides encased within Metal-Insulator-Metal (MIM) structures can\ndemonstrate both unipolar and bipolar switching mechanisms, rendering them the\ncapability to exhibit a multitude of resistive states and ultimately function\nas memory elements. Identifying the vital physical mechanisms behind resistive\nswitching can enable these devices to be utilized more efficiently, reliably\nand in the long-term. In this paper, we present a new approach for analysing\nresistive switching by modelling the active core of two terminal devices as 2D\nand 3D grid circuit breaker networks. This model is employed to demonstrate\nthat substantial resistive switching can only be supported by the formation of\ncontinuous current percolation channels, while multi-state capacity is ascribed\nto the establishment and annihilation of multiple channels.",
        "positive": "Inter-surface interaction via phonon in three-dimensional topological\n  insulator: We theoretically study the phonon mediated intersurface electron-electron\ninteractions on the pseudo two-dimensional metallic states at the two surfaces\nof a three-dimensional topological insulator. From a model of a\nthree-dimensional topological insulator including the phonon excitation in it,\nwe derive the effective Lagrangian which describes the two surface metallic\nstates and the interaction between them. The intersurface electron-electron\ninteractions can be either repulsive or attractive depending on parameters such\nas temperature, the speed of the phonon, and the Fermi velocity of the surface\nstates. The attractive interaction removes the Dirac nodes from the two surface\nstates as a result of the spontaneous symmetry breaking. On the basis of the\ncalculated results, we also discuss how to tune the inter-surface interaction."
    },
    {
        "anchor": "Spin transmission control in helical magnetic fields: We calculate spin transport in two-dimensional waveguides in the presence of\nspatially modulated Zeeman-split energy bands. We show that in a regime where\nthe spin evolution is predominantly adiabatic the spin backscattering rate can\nbe tuned via diabatic Landau-Zener transitions between the spin-split bands [C.\nBetthausen et. al., Science 337, 324 (2012)]. This mechanism is tolerant\nagainst spin-independent scattering processes. Completely spin-polarized\nsystems show full spin backscattering, and thus current switching. In partially\nspin-polarized systems a spatial sequence of Landau-Zener transition points\nenhances the resistance modulation via reoccupation of backscattered\nspin-polarized transport modes. We discuss a possible application as a spin\ntransistor.",
        "positive": "Allowed charge transfers between coherent conductors driven by a\n  time-dependent scatterer: We derive constraints on the statistics of the charge transfer between two\nconductors in the model of arbitrary time-dependent instant scattering of\nnon-interacting fermions at zero temperature. The constraints are formulated in\nterms of analytic properties of the generating function: its zeroes must lie on\nthe negative real axis. This result generalizes existing studies for scattering\nby a time-independent scatterer under time-dependent bias voltage."
    },
    {
        "anchor": "Leakage Current Reduction Techniques in Poly-Si TFTs for Active Matrix\n  Liquid Crystal Displays:A Comprehensive Study: This paper critically examines the leakage current reduction techniques for\nimproving the performance of poly-Si TFTs used in active matrix liquid crystal\ndisplays. This is a first comprehensive study in literature on this topic. The\nreview assesses important proposals to circumvent the leakage current problem\nin poly-Si TFTs and a short evaluation of strengths and weaknesses specific to\neach method is presented. Also, a new device structure called the Triple Gate\npoly-Si TFT (TG-TFT) is discussed. The key idea in the operation of this device\nis to make the dominant conduction mechanism in the channel to be controlled by\nthe accumulation charge density modulation by the gate (ACMG) and not by the\ngate-induced grain barrier lowering (GIGBL). Using twodimensional and\ntwo-carrier device simulation, it is demonstrated that the TG-TFT exhibits a\nsignificantly diminished pseudo-subthreshold conduction leading to several\norders of magnitude reduction in the OFF state leakage current when compared to\na conventional poly-Si TFT. The reasons for the improved performance are\nexplained.",
        "positive": "Electron Refrigeration in the Tunneling Approach: The qualities of electron refrigeration by means of tunnel junctions between\nsuperconducting and normal--metal electrodes are studied theoretically. A\nsuitable approximation of the basic expression for the heat current across\nthose tunnel junctions allows the investigation of several features of the\ndevice such as its optimal bias voltage, its maximal heat current, its optimal\nworking point, and the maximally gained temperature reduction. Fortunately, the\nobtained results can be compared with those of a recent experiment."
    },
    {
        "anchor": "Observation of the single-electron regime in a highly tunable silicon\n  quantum dot: We report on low-temperature electronic transport measurements of a silicon\nmetal-oxide-semiconductor quantum dot, with independent gate control of\nelectron densities in the leads and the quantum dot island. This architecture\nallows the dot energy levels to be probed without affecting the electron\ndensity in the leads, and vice versa. Appropriate gate biasing enables the dot\noccupancy to be reduced to the single-electron level, as evidenced by\nmagnetospectroscopy measurements of the ground state of the first two charge\ntransitions. Independent gate control of the electron reservoirs also enables\ndiscrimination between excited states of the dot and density of states\nmodulations in the leads.",
        "positive": "Influence of Contacts and Applied Voltage on a Structure of a Single GaN\n  Nanowire: Semiconductor nanowires (NWs) have a broad range of applications for nano-\nand optoelectronics. The strain field of gallium nitride (GaN) NWs could be\nsignificantly changed when contacts are applied to them to form a final device,\nespecially considering the piezoelectric properties of GaN. Investigation of\ninfluence of the metallic contacts on the structure of the NWs is of high\nimportance for their applications in real devices. We have studied a series of\ndifferent type of contacts and influence of the applied voltage bias on the\ncontacted GaN NWs with the length of about 3 to 4 micrometers and with two\ndifferent diameters of 200 nm and 350 nm. It was demonstrated that the NWs with\nthe diameter of 200 nm are bend already by the interaction with the substrate.\nFor all GaN NWs, significant structural changes were revealed after the\ncontacts deposition. The results of our research may contribute to the future\noptoelectronic applications of the GaN nanowires."
    },
    {
        "anchor": "Effect of parallel magnetic field on Klein tunneling in $pn$ and $pnp$\n  graphene trilayer junctions: The effect of a parallel magnetic field $B$ and a potential substrate on the\ntransmission, conductivity, and Fano factor of a biased ABC-stacked $pn$ and\n$pnp$ trilayer graphene junction (ABC-TLG) is investigated theoretically at low\nenergy. We discovered that, in the presence of a high magnetic field $B=1400$T,\nthe ABC-TLG can exhibit new Klein tunneling at two new incidence $k_y$ values,\nin addition to the usual value of $k_y=0$ and whatever the energy value is.\nIndeed, the transmission of ABC-TLG via $ pn $ and $ pnp $ junctions is\ntransformed into a three-separate transmission of single-like graphene (SLG),\nwith Klein tunneling appearing at $k_y=0$ and $k_y=\\pm\\kappa$ ($\\kappa$ is\nhighly dependent on $B$). Furthermore, the conductivity $\\sigma$ and Fano\nfactor $F$ behave similarly to SLG, with ABC-TLG having the lowest\n$\\sigma=3g_0/\\pi$ and highest $F=1/3$ at $B=1400$T and\n$\\sigma_{\\text{TLG}}=3\\sigma_{\\text{SLG}}$.",
        "positive": "Anisotropic three-dimensional quantum Hall effect and magnetotransport\n  in mesoscopic Weyl semimetals: Weyl semimetals are emerging to become a new class of quantum-material\nplatform for various novel phenomena. Especially, the Weyl orbit made from\nsurface Fermi arcs and bulk relativistic states is expected to play a key role\nin magnetotransport, leading even to a three-dimensional quantum Hall effect\n(QHE). It is experimentally and theoretically important although yet unclear\nwhether it bears essentially the same phenomenon as the conventional\ntwo-dimensional QHE. We discover an unconventional fully three-dimensional\nanisotropy in the quantum transport under magnetic field. Strong suppression\nand even disappearance of QHE occur when Hall-bar current is rotated away from\nbeing transverse to parallel with respect to the Weyl point alignment, which is\nattributed to a peculiar absence of conventional bulk-boundary correspondence.\nBesides, transport along the magnetic field can exhibit a remarkable reversal\nfrom negative to positive magnetoresistance. These results establish the\nuniqueness of this QHE system as a novel three-dimensional quantum matter."
    },
    {
        "anchor": "Solitonic in-gap modes in a superconductor-quantum antiferromagnet\n  interface: Bound states at interfaces between superconductors and other materials are a\npowerful tool to characterize the nature of the involved systems, and to\nengineer elusive quantum excitations. In-gap excitations of conventional s-wave\nsuperconductors occur, for instance, at magnetic impurities with net magnetic\nmoment breaking time-reversal symmetry. Here we show that interfaces between a\nsuperconductor and a quantum antiferromagnet can host robust in-gap\nexcitations, without breaking time-reversal symmetry. We illustrate this\nphenomenon in a one-dimensional model system with an interface between a\nconventional s-wave superconductor and a one-dimensional Mott insulator\ndescribed by a standard Hubbard model. This genuine many-body problem is solved\nexactly by employing a combination of kernel polynomial and tensor network\ntechniques. We unveil the nature of such zero modes by showing that they can be\nadiabatically connected to solitonic solutions between a superconductor and a\nclassical antiferromagnet. Our results put forward a new class of in-gap\nexcitations between superconductors and a disordered quantum spin phase can be\nrelevant for a wider range of heterostructures.",
        "positive": "Anisotropic modification of the effective hole $g$-factor by\n  electrostatic confinement: We investigate effects of lateral confinement on spin splitting of energy\nlevels in 2D hole gases grown on [311] GaAs. We found that lateral confinement\nenhances anisotropy of spin splitting relative to the 2D gas for both confining\ndirections. Unexpectedly, the effective $g$-factor does not depend on the 1D\nenergy level number $N$ for $B\\|[0\\bar{1}1]$ while it has strong $N$-dependence\nfor $B\\|[\\bar{2}33]$. Apart from quantitative difference in the spin splitting\nof energy levels for the two orthogonal confinement directions we also report\nqualitative differences in the appearance of spin-split plateaus, with\nnon-quantized plateaus observed only for the confinement in $[0\\bar{1}1]$\ndirection. In our samples we can clearly associate the difference with\nanisotropy of spin-orbit interactions."
    },
    {
        "anchor": "Spin Hall magnetoresistance in heterostructures consisting of\n  noncrystalline paramagnetic YIG and Pt: The spin Hall magnetoresistance (SMR) effect arises from spin-transfer\nprocesses across the interface between a spin Hall active metal and an\ninsulating magnet. While the SMR response of ferrimagnetic and\nantiferromagnetic insulators has been studied extensively, the SMR of a\nparamagnetic spin ensemble is not well established. Thus, we investigate herein\nthe magnetoresistive response of as-deposited yttrium iron garnet/platinum thin\nfilm bilayers as a function of the orientation and the amplitude of an\nexternally applied magnetic field. Structural and magnetic characterization\nshow no evidence for crystalline order or spontaneous magnetization in the\nyttrium iron garnet layer. Nevertheless, we observe a clear magnetoresistance\nresponse with a dependence on the magnetic field orientation characteristic for\nthe SMR. We propose two models for the origin of the SMR response in\nparamagnetic insulator/Pt heterostructures. The first model describes the SMR\nof an ensemble of non-interacting paramagnetic moments, while the second model\ndescribes the magnetoresistance arising by considering the total net moment.\nInterestingly, our experimental data are consistently described by the net\nmoment picture, in contrast to the situation in compensated ferrimagnets or\nantiferromagnets.",
        "positive": "Bell inequalities and entanglement in solid state devices: Bell-inequality checks constitute a probe of entanglement -- given a source\nof entangled particles, their violation are a signature of the non-local nature\nof quantum mechanics. Here, we study a solid state device producing pairs of\nentangled electrons, a superconductor emitting Cooper pairs properly split into\nthe two arms of a normal-metallic fork with the help of appropriate filters. We\nformulate Bell-type inequalities in terms of current-current cross-correlators,\nthe natural quantities measured in mesoscopic physics; their violation provides\nevidence that this device indeed is a source of entangled electrons."
    },
    {
        "anchor": "Resonant tunneling and the multichannel Kondo problem: the quantum\n  Brownian motion description: We study mesoscopic resonant tunneling as well as multichannel Kondo problems\nby mapping them to a first-quantized quantum mechanical model of a particle\nmoving in a multi-dimensional periodic potential with Ohmic dissipation. From a\nrenormalization group analysis, we obtain phase diagrams of the quantum\nBrownian motion model with various lattice symmetries. For a symmorphic\nlattice, there are two phases at T=0: a localized phase in which the particle\nis trapped in a potential minimum, and a free phase in which the particle is\nunaffected by the periodic potential. For a non-symmorphic lattice, however,\nthere may be an additional intermediate phase in which the particle is neither\nlocalized nor completely free. The fixed point governing the intermediate phase\nis shown to be identical to the well-known multichannel Kondo fixed point in\nthe Toulouse limit as well as the resonance fixed point of a quantum dot model\nand a double-barrier Luttinger liquid model. The mapping allows us to compute\nthe fixed-poing mobility $\\mu^*$ of the quantum Brownian motion model exactly,\nusing known conformal-field-theory results of the Kondo problem. From the\nmobility, we find that the peak value of the conductance resonance of a\nspin-1/2 quantum dot problem is given by $e^2/2h$. The scaling form of the\nresonance line shape is predicted.",
        "positive": "Charge redistribution between cyclotron-resolved edge states at high\n  imbalance: We use a quasi-Corbino sample geometry with independent contacts to different\nedge states in the quantum Hall effect regime to investigate a charge\nredistribution between cyclotron-split edge states at high imbalance. We also\nmodify Buttiker formalism by introducing local transport characteristics in it\nand use this modified Buttiker picture to describe the experimental results. We\nfind that charge transfer between cyclotron-split edge states at high imbalance\ncan be described by a single parameter, which is a transferred between edge\nstates portion of the available for transfer part of the electrochemical\npotential imbalance. This parameter is found to be independent of the\nparticular sample characteristics, describing fundamental properties of the\ninter-edge-state scattering. From the experiment we obtain it in the dependence\non the voltage imbalance between edge states and propose a qualitative\nexplanation to the experimental findings."
    },
    {
        "anchor": "Mesoscopic fluctuations in the spin-electric susceptibility due to\n  Rashba spin-orbit interaction: We investigate mesoscopic fluctuations in the spin polarization generated by\na static electric field and by Rashba spin-orbit interaction in a disordered 2D\nelectron gas. In a diagrammatic approach we find that the out-of-plane\npolarization -- while being zero for self-averaging systems -- exhibits large\nsample-to-sample fluctuations which are shown to be well within experimental\nreach. We evaluate the disorder-averaged variance of the susceptibility and\nfind its dependence on magnetic field, spin-orbit interaction, dephasing, and\nchemical potential difference.",
        "positive": "Testing of two-dimensional local approximations in the current-spin and\n  spin-density-functional theories: We study a model quantum dot system in an external magnetic field by using\nboth the spin-density-functional theory and the current-spin-density-functional\ntheory. The theories are used with local approximations for the spin-density\nand the vorticity. The reliabilities of different parametrizations for the\nexchange-correlation functionals are tested by comparing the ensuing energetics\nwith quantum Monte Carlo results. The limit where the vorticity dependence\nshould be used in the exchange-correlation functionals is discussed."
    },
    {
        "anchor": "Quantum Anomalous Hall Effect in Perfectly Compensated Collinear\n  Antiferromagnetic Thin Films: We show that the quantum anomalous Hall effect almost always occurs in\nmagnetic topological insulator thin films whenever the top and bottom surface\nlayer magnetizations are parallel, independent of the interior layer\nmagnetization configuration. Using this criteria we identify structures that\nhave a quantum anomalous Hall effect even though they have collinear magnetic\nstructures with no net magnetization, and discuss strategies for realizing\nthese interesting magnetic states experimentally.",
        "positive": "Quasiparticle spectra and excitons of organic molecules deposited on\n  substrates: G0W0-BSE approach applied to benzene on graphene and metallic\n  substrates: We present an alternative methodology for calculating the quasi-particle\nenergy, energy loss, and optical spectra of a molecule deposited on graphene or\na metallic substrate. To test the accuracy of the method it is first applied to\nthe isolated benzene (C6H6) molecule. The quasiparticle energy levels and\nespecially the energies of the benzene excitons (triplet, singlet, optically\nactive and inactive) are in very good agreement with available experimental\nresults. It is shown that the vicinity of the various substrates\n(pristine/doped graphene or (jellium) metal surface) reduces the quasiparticle\nHOMO-LUMO gap by an amount that slightly depends on the substrate type. This is\nconsistent with the simple image theory predictions. It is even shown that the\nsubstrate does not change the energy of the excitons in the isolated molecule.\nWe prove (in terms of simple image theory) that energies of the excitons are\nindeed influenced by two mechanisms which cancel each other. We demonstrate\nthat the benzene singlet optically active (E1u) exciton couples to real\nelectronic excitations in the substrate. This causes it substantial decay, such\nas {\\Gamma} = 174 meV for pristine graphene and {\\Gamma} = 362 meV for metal\nsurfaces as the substrate. However, we find that doping graphene does not\ninfluence the E1u exciton decay rate."
    },
    {
        "anchor": "Photo-induced electron pairing in a driven cavity: We demonstrate how virtual scattering of laser photons inside a cavity via\ntwo-photon processes can induce controllable long-range electron interactions\nin two-dimensional materials. We show that laser light that is\nred(blue)-detuned from the cavity yields attractive(repulsive) interactions,\nwhose strength is proportional to the laser intensity. Furthermore, we find\nthat the interactions are not screened effectively except at very low\nfrequencies. For realistic cavity parameters, laser-induced heating of the\nelectrons by inelastic photon scattering is suppressed and coherent electron\ninteractions dominate. When the interactions are attractive, they cause an\ninstability in the Cooper channel at a temperature proportional to the square\nroot of the driving intensity. Our results provide a novel route for\nengineering electron interactions in a wide range of two-dimensional materials\nincluding AB-stacked bilayer graphene and the conducting interface between\nLaAlO3 and SrTiO3.",
        "positive": "Unusual reflection of electromagnetic radiation from a stack of graphene\n  layers at oblique incidence: We study the interaction of electromagnetic (EM) radiation with single-layer\ngraphene and a stack of parallel graphene sheets at arbitrary angles of\nincidence. It is found that the behavior is qualitatively different for\ntransverse magnetic (or p-polarized) and transverse electric (or s-polarized)\nwaves. In particular, the absorbance of single-layer graphene attains minimum\n(maximum) for p (s) polarization, at the angle of total internal reflection\nwhen the light comes from a medium with a higher dielectric constant. In the\ncase of equal dielectric constants of the media above and beneath graphene, for\ngrazing incidence graphene is almost 100% transparent to p-polarized waves and\nacts as a tunable mirror for the s-polarization. These effects are enhanced for\nthe stack of graphene sheets, so the system can work as a broad band polarizer.\nIt is shown further that a periodic stack of graphene layers has the properties\nof an one-dimensional photonic crystal, with gaps (or stop--bands) at certain\nfrequencies. When an incident EM wave is reflected from this photonic crystal,\nthe tunability of the graphene conductivity renders the possibility of\ncontrolling the gaps, and the structure can operate as a tunable\nspectral--selective mirror."
    },
    {
        "anchor": "GHz nanomechanical resonator in an ultraclean suspended graphene p-n\n  junction: We demonstrate high-frequency mechanical resonators in ballistic graphene p-n\njunctions. Fully suspended graphene devices with two bottom gates exhibit\nballistic bipolar behavior after current annealing. We determine the graphene\nmass density and built-in tension for different current annealing steps by\ncomparing the measured mechanical resonant response to a simplified membrane\nmodel. We consistently find that after the last annealing step the mass density\ncompares well with the expected density of pure graphene. In a graphene\nmembrane with high built-in tension, but still of macroscopic size with\ndimensions 3 $\\times$ 1 $\\mu m^{2}$, a record resonance frequency of 1.17 GHz\nis observed after the final current annealing step. We further compare the\nresonance response measured in the unipolar with the one in the bipolar regime.\nRemarkably, the resonant signals are strongly enhanced in the bipolar regime.\nThis enhancement is caused in part by the Fabry-Perot resonances that appear in\nthe bipolar regime and possibly also by the photothermoelectric effect that can\nbe very pronounced in graphene p-n junctions under microwave irradiation.",
        "positive": "Exact magnetic field control of nitrogen-vacancy center spin for\n  realizing fast quantum logic gates: The negatively charged nitrogen-vacancy (NV) center spin in diamond can be\nused to realize quantum computation and to sense magnetic fields. Its spin\ntriplet consists of three levels labeled with its spin z-components of +1, 0,\nand -1. Without external field, the +1 and -1 states are degenerate and higher\nthan the 0 state due to the zero-field splitting. By taking the symmetrical and\nanti-symmetrical superpositions of the +1 and -1 states as our qubit basis, we\nobtain exact evolution operator of the NV center spin under time-dependent\nmagnetic field by mapping the three-level system on time-dependent quantum\ntwo-level systems with exact analytical solutions. With our exact evolution\noperator of the NV center spin including three levels, we show that arbitrary\nqubits can be prepared from the starting 0 state and arbitrary rapid quantum\nlogic gates of these qubits can be realized with magnetic fields. In addition,\nit is made clear that the typical quantum logic gates can be accomplished\nwithin a few nanoseconds and the fidelity can be very high because only\nmagnetic field strength needs to be controlled in this approach. These results\nshould be useful to realizing quantum computing with the NV center spin systems\nin diamond and exploring other effects and applications."
    },
    {
        "anchor": "Two-dimensional assembly of gold nanoparticles grafted with\n  charged-end-group polymers: Hypothesis: Introducing charged terminal groups to polymers that graft\nnanoparticles enables Coulombic control over their assembly by tuning the pH\nand salinity of aqueous suspensions. Experiments: Gold nanoparticles (AuNPs)\nare grafted with poly(ethylene glycol) (PEG) terminated with CH3\n(charge-neutral), COOH (negatively charged), or NH2 (positively charged)\ngroups. The nanoparticles are characterized using dynamic light scattering,\nzeta-potential, and thermal gravimetric analysis. Liquid surface X-ray\nreflectivity (XR) and grazing incidence small-angle X-ray scattering (GISAXS)\ntechniques are employed to determine the density profile and in-plane structure\nof the AuNP assembly across and on the aqueous surface. Findings: The assembly\nof PEG-AuNPs at the liquid/vapor interface can be tuned by adjusting pH or\nsalinity, particularly for COOH terminals. However, the effect is less\npronounced for NH2 terminals. These distinct assembly behaviors are attributed\nto the overall charge of PEG-AuNPs and the conformation of PEG. The COOH-PEG\ncorona is the most compact, resulting in smaller superlattice constants. The\nnet charge per particle depends not only on the PEG terminal groups but also on\nthe cation sequestration of PEG and the intrinsic negative charge of the AuNP\nsurface. NH2-PEG, due to its closeness to overall charge neutrality and the\npresence of hydrogen bonding, enables the assembly of NH2-PEG-AuNPs more\nreadily.",
        "positive": "Magneto-elastic switching of magnetostrictive nanomagnets with in-plane\n  shape anisotropy: We theoretically study the effect of a material defect (material void) on\nswitching errors associated with magneto-elastic switching of magnetization in\nelliptical magnetostrictive nanomagnets having in-plane magnetic anisotropy. We\nfind that the error probability increases significantly in the presence of the\ndefect, indicating that magneto-elastic switching is particularly vulnerable to\nmaterial imperfections. Curiously, there is a critical stress value that gives\nthe lowest error probability in both defect-free and defective nanomagnets. The\ncritical stress is much higher in defective nanomagnets than in defect-free\nones. Since it is more difficult to generate the critical stress in small\nnanomagnets than in large nanomagnets (having the same energy barrier for\nthermal stability), it would be a challenge to downscale magneto-elastically\nswitched nanomagnets in memory and other applications where reliable switching\nis required. This is likely to be further exacerbated by the presence of\ndefects."
    },
    {
        "anchor": "Multi-scale Incoherent Electronic Transport Properties in Non-ideal CVD\n  Graphene Devices: In this research work, roll-to-roll chemical vapor deposited graphene device\nelectronic transport properties are benchmarked to elucidate and comprehend\nmobility degradation in the real-world commercial application of graphene\ndevices. Multifarious device design morphology in the graphene and\ntwo-dimensional material with diverse background materials compositions and\nprocessing recipes incorporate various scattering sources in the devices. To\nunderstand the nature of mobility degradation in roll-to-roll chemical vapor\ndeposited graphene production devices, we employed multi-scale, multi-physics\nbottom-up, non-equilibrium Green's function-based quantum transport formalism.\nIn this framework, we numerically incorporate various scattering mechanisms to\ndeduce the measurand mobility at the last stage of computation to observe\nvarious scattering potential impacts on the production device performance. We\nhave analyzed the variation in transmission, electronic charge density,\nelectrostatic Poisson potential, energy-resolved flux density, and\ncurrent-voltage characteristics and inferred the Drude mobility with different\nscattering potentials in various graphene devices. These scattering mechanisms\ntreat scattering potentials as the first-order phonon Dyson self-energy term in\nthe third loop of the two-looped self-consistent Poisson-Non-equilibrium\nGreen's function iteration. Furthermore, multiple scattering scenarios\nimplemented through a generalized contact self-energy scattering calculation\nascribe the effect of contact scattering to the graphene device in\nquasi-ballistic transport limit. In this scheme, the effect of all the physical\nscattering mechanisms is lumped into one energy uncertainty or scattering rate\nparameter to include in the device's contact self-energy interaction term bound\nby the upper limit of Heisenberg uncertainty for the interacting quantum\ncharged particles.",
        "positive": "An Integrated Tantalum Sulfide - Boron Nitride - Graphene Oscillator: A\n  Charge-Density-Wave Device Operating at Room Temperature: The charge-density-wave (CDW) phase is a macroscopic quantum state consisting\nof a periodic modulation of the electronic charge density accompanied by a\nperiodic distortion of the atomic lattice in quasi-1D or layered 2D metallic\ncrystals. Several layered transition metal dichalcogenides, such as 1T-TaSe2,\n1T-TaS2 and 1T-TiSe2, exhibit unusually high transition temperatures to\ndifferent CDW symmetry-reducing phases. These transitions can be affected by\nenvironmental conditions, film thickness and applied electric bias. However,\ndevice applications of these intriguing systems at room temperature or their\nintegration with other 2D materials have not been explored. Here we show that\nin 2D CDW 1T-TaS2, the abrupt change in the electrical conductivity and\nhysteresis at the transition point between nearly-commensurate and\nincommensurate charge-density-wave phases can be used for constructing an\noscillator that operates at room temperature. The hexagonal boron nitride was\ncapped on 1T-TaS2 thin film to provide protection from oxidation, and an\nintegrated graphene transistor provides a voltage tunable, matched,\nlow-resistance load enabling precise voltage control of the oscillator\nfrequency. The integration of these three disparate two-dimensional materials,\nin a way that exploits the unique properties of each, yields a simple,\nminiaturized, voltage-controlled oscillator device. Theoretical considerations\nsuggest that the upper limit of oscillation frequency to be in the THz regime."
    },
    {
        "anchor": "Bloch-point-mediated topological transformations of magnetic domain\n  walls in cylindrical nanowires: Cylindrical nanowires made of soft magnetic materials, in contrast to thin\nstrips, may host domain walls of two distinct topologies. Unexpectedly, we\nevidence experimentally the dynamic transformation of topology upon wall motion\nabove a field threshold. Micromagnetic simulations highlight the underlying\nprecessional dynamics for one way of the transformation, involving the\nnucleation of a Bloch-point singularity, however, fail to reproduce the reverse\nprocess. This rare discrepancy between micromagnetic simulations and\nexperiments raises fascinating questions in material and computer science.",
        "positive": "Interplay of Aharonov-Bohm, chirality, and aspect ratio effects in the\n  axial conductance of a nanotube: A magnetic flux applied along the axis of a nanotube can counteract the\neffect of the tube chirality and dramatically affect its conductance, leading\nto a way to determine the chirality of a nanotube. The effect of the applied\nflux is strongest in the long tube limit where the conductance is (i) either a\nsequence of sharp $4e^{2}/h$ height peaks located at integer (in units of the\nflux quantum) values of the flux (for an armchair tube) or (ii) a periodic\nsequence of pairs of $2e^{2}/h$ height peaks for a chiral tube, with the\nspacing determined by the chirality. In the short tube limit the conductance\ntakes on the value that gives the universal conductivity of an undoped graphene\nsheet, with a small amplitude modulation periodic in the flux."
    },
    {
        "anchor": "Radiative Pattern of Intralayer and Interlayer Excitons in\n  Two-Dimensional WS2/WSe2 Heterostructure: Two-dimensional (2D) heterostructures (HS) formed by transition-metal\ndichalcogenide (TMDC) monolayers offer a unique platform for the study of\nintralayer and interlayer excitons as well as moir\\'e-pattern-induced features.\nParticularly, the dipolar charge-transfer exciton comprising an electron and a\nhole, which are confined to separate layers of 2D semiconductors and\nCoulomb-bound across the heterojunction interface, has drawn considerable\nattention in the research community. On the one hand, it bears significance for\noptoelectronic devices, e.g. in terms of charge carrier extraction from\nphotovoltaic devices. On the other hand, its spatially indirect nature and\ncorrespondingly high longevity among excitons as well as its out-of-plane\ndipole orientation render it attractive for excitonic Bose-Einstein\ncondensation studies, which address collective coherence effects, and for\nphotonic integration schemes with TMDCs. Here, we demonstrate the interlayer\nexcitons' out-of-plane dipole orientation through angle-resolved spectroscopy\nof the HS photoluminescence at cryogenic temperatures, employing a\ntungsten-based TMDC HS. Within the measurable light cone, the directly-obtained\nradiation profile of this species clearly resembles that of an in-plane emitter\nwhich deviates from that of the intralayer bright excitons as well as the other\nexcitonic HS features recently attributed to artificial superlattices formed by\nmoir\\'e patterns.",
        "positive": "Rapidly Rotating Atomic Gases: This article reviews developments in the theory of rapidly rotating\ndegenerate atomic gases. The main focus is on the equilibrium properties of a\nsingle component atomic Bose gas, which (at least at rest) forms a\nBose-Einstein condensate. Rotation leads to the formation of quantized vortices\nwhich order into a vortex array, in close analogy with the behaviour of\nsuperfluid helium. Under conditions of rapid rotation, when the vortex density\nbecomes large, atomic Bose gases offer the possibility to explore the physics\nof quantized vortices in novel parameter regimes. First, there is an\ninteresting regime in which the vortices become sufficiently dense that their\ncores -- as set by the healing length -- start to overlap. In this regime, the\ntheoretical description simplifies, allowing a reduction to single particle\nstates in the lowest Landau level. Second, one can envisage entering a regime\nof very high vortex density, when the number of vortices becomes comparable to\nthe number of particles in the gas. In this regime, theory predicts the\nappearance of a series of strongly correlated phases, which can be viewed as\n{\\it bosonic} versions of fractional quantum Hall states. This article\ndescribes the equilibrium properties of rapidly rotating atomic Bose gases in\nboth the mean-field and the strongly correlated regimes, and related\ntheoretical developments for Bose gases in lattices, for multi-component Bose\ngases, and for atomic Fermi gases. The current experimental situation and\noutlook for the future are discussed in the light of these theoretical\ndevelopments."
    },
    {
        "anchor": "Macroscopic Quantum Coherence in a Magnetic Nanoparticle Above the\n  Surface of a Superconductor: We study macroscopic quantum tunneling of the magnetic moment in a\nsingle-domain particle placed above the surface of a superconductor. Such a\nsetup allows one to manipulate the height of the energy barrier, preserving the\ndegeneracy of the ground state. The tunneling amplitude and the effect of the\ndissipation in the superconductor are computed.",
        "positive": "Bulk-edge correspondence in topological transport and pumping: The bulk-edge correspondence (BEC) refers to a one-to-one relation between\nthe bulk and edge properties ubiquitous in topologically nontrivial systems.\nDepending on the setup, BEC manifests in different forms and govern the\nspectral and transport properties of topological insulators and semimetals.\nAlthough the topological pump is theoretically old, BEC in the pump has been\nestablished just recently [1] motivated by the state-of-the-art experiments\nusing cold atoms [2,3]. The center of mass (CM) of a system with boundaries\nshows a sequence of quantized jumps in the adiabatic limit associated with the\nedge states. Although the bulk is adiabatic, the edge is inevitably\nnon-adiabatic in the experimental setup or in any numerical simulations. Still\nthe pumped charge is quantized and carried by the bulk. Its quantization is\nguaranteed by a compensation between the bulk and edges. We show that in the\npresence of disorder the pumped charge continues to be quantized despite the\nappearance of non-quantized jumps."
    },
    {
        "anchor": "Nuclear dynamics at molecule-metal interfaces: A pseudoparticle\n  perspective: We discuss nuclear dynamics at molecule-metal interfaces including\nnon-equilibrium molecular junctions. Starting from the many-body states\n(pseudoparticle) formulation of the molecule-metal system in the molecular\nvibronic basis, we introduce gradient expansion in order to reduce the\nadiabatic nuclear dynamics (that is, nuclear dynamics on a single molecular\npotential surface) into its semi-classical form while maintaining the effect of\nthe non-adiabatic electronic transitions between different molecular charge\nstates. This yields a set of equations for the nuclear dynamics in the presence\nof these non-adiabatic transitions, which reproduce surface hopping formulation\nin the limit of small metal-molecule coupling (where broadening of the\nmolecular energy levels can be disregarded) and Ehrenfest dynamics (motion on\nthe potential of mean force) when information on the different charging states\nis traced out, which is relevant when this coupling is strong.",
        "positive": "Current induced torques between ferromagnets and compensated\n  antiferromagnets: symmetry and phase coherence effects: It is shown that the current-induced torques between a ferromagnetic layer\nand an antiferromagnetic layer with a compensated interface vanish when the\nferromagnet is aligned with an axis of spin-rotation symmetry of the\nantiferromagnet. For properly chosen geometries this implies that the current\ninduced torque can stabilize the out-of-plane (or hard axis) orientation of the\nferromagnetic layer. This current-induced torque relies on phase coherent\ntransport, and we calculate the robustness of this torque to phase breaking\nscattering. From this it is shown that the torque is not linearly dependent on\napplied current, but has an absolute maximum."
    },
    {
        "anchor": "Interaction effects on magnetooscillations in a two-dimensional electron\n  gas: Motivated by recent experiments, we study the interaction corrections to the\ndamping of magnetooscillations in a two-dimensional electron gas (2DEG). We\nidentify leading contributions to the interaction-induced damping which are\ninduced by corrections to the effective mass and quantum scattering time. The\ndamping factor is calculated for Coulomb and short-range interaction in the\nwhole range of temperatures, from the ballistic to the diffusive regime. It is\nshown that the dominant effect is that of the renormalization of the effective\nelectron mass due to the interplay of the interaction and impurity scattering.\nThe results are relevant to the analysis of experiments on magnetooscillations\n(in particular, for extracting the value of the effective mass) and are\nexpected to be useful for understanding the physics of a high-mobility 2DEG\nnear the apparent metal-insulator transition.",
        "positive": "Multistable rippling of graphene on SiC: A Density Functional Theory\n  study: Graphene monolayer grown by Si evaporation from the 0001 surface of SiC\ndisplays a moir\\'e pattern of corrugation whose structure is ambiguous:\ndifferent measurements and theoretical studies show either protruding bumps\nsurrounded by valleys, or, reversely, wells surrounded by crests. Here we\naddress the fine structure of monolayer graphene on SiC by means of Density\nFunctional Theory, using a model including the full symmetry of the system and\nthe substrate (1648 atoms) and therefore realistically reproducing the\nexperimental sample. We find that accurate treatment of the vdW interactions\nbetween monolayer and the underlying substrate-bound buffer layer is crucial in\nstabilizing one or the opposite corrugation pattern, which explain the\ndifferent results and measurement available in the literature. Our study\nindicates that at low temperature a state more closely following the topography\nof the underneath buffer layer is stabilized, while others are metastable.\nSince environmental conditions (e.g. temperature or doping) can influence the\nvdW forces and reduce the energy differences, this system is prone to\nexternally driven switching between different (opposite) corrugation states. In\nturn, corrugation is related to local reactivity and to electronic properties\nof graphene. This opens to potentially interesting applications in\nnano-electronics or tailored graphene chemical functionalization."
    },
    {
        "anchor": "Performance limits due to thermal transport in graphene single-photon\n  bolometers: In high-sensitivity bolometers and calorimeters, the photon absorption often\noccurs at a finite distance from the temperature sensor to accommodate antennas\nor avoid the degradation of superconducting circuitry exposed to radiation. As\na result, thermal propagation from the input to the temperature readout can\ncritically affect detector performance. In this report we model the performance\nof a graphene bolometer, accounting for electronic thermal diffusion and\ndissipation via electron-phonon coupling at low temperatures in three regimes:\nclean, supercollision, and resonant scattering. Our results affirm the\nfeasibility of a superconducting readout without Cooper-pair breaking by mid-\nand near-infrared photons, and provide a recipe for designing graphene\nabsorbers for calorimetric single-photon detectors. We investigate the tradeoff\nbetween the input-readout distance and detector efficiency, and predict an\nintrinsic timing jitter of ~2.7 ps. Based on our result, we propose a\nspatial-mode-resolving photon detector to increase communication bandwidth.",
        "positive": "Non-Hermitian Topological Sensors: We introduce and study a novel class of sensors whose sensitivity grows\nexponentially with the size of the device. Remarkably, this drastic enhancement\ndoes not rely on any fine-tuning, but is found to be a stable phenomenon immune\nto local perturbations. Specifically, the physical mechanism behind this\nstriking phenomenon is intimately connected to the anomalous sensitivity to\nboundary conditions observed in non-Hermitian topological systems. We outline\nconcrete platforms for the practical implementation of these non-Hermitian\ntopological sensors (NTOS) ranging from classical meta-materials to synthetic\nquantum-materials."
    },
    {
        "anchor": "Transmission probability through small interacting systems: application\n  to a series of quantum dots: We apply a theory for the transmission probability of small interacting\nsystems, which was formulated based on the Kubo formalism in our previous\nstudy, to a series of quantum dots described by the N-impurity Anderson model.\nIn this report, we present the transmission pobability for the system of N=2\ncalculated using the order $U^2$ self-energy and vertex corrections.\nParticularly, we examine the features in the two typical parameter regions,\n$t<\\Gamma$ and $t>\\Gamma$, where the Kondo effect or the inter-dot correlation\ndominates. Here, $t$ is the inter-dot transfer and $\\Gamma$ is the level\nbroadening caused by the coupling with the noninteracting leads.",
        "positive": "Resonant tunnelling between the chiral Landau states of twisted graphene\n  lattices: A new class of multilayered functional materials has recently emerged in\nwhich the component atomic layers are held together by weak van der Waals\nforces that preserve the structural integrity and physical properties of each\nlayer. An exemplar of such a structure is a transistor device in which\nrelativistic Dirac Fermions can resonantly tunnel through a boron nitride\nbarrier, a few atomic layers thick, sandwiched between two graphene electrodes.\nAn applied magnetic field quantises graphene's gapless conduction and valence\nband states into discrete Landau levels, allowing us to resolve individual\ninter-Landau level transitions and thereby demonstrate that the energy,\nmomentum and chiral properties of the electrons are conserved in the tunnelling\nprocess. We also demonstrate that the change in the semiclassical cyclotron\ntrajectories, following a tunnelling event, is a form of Klein tunnelling for\ninter-layer transitions."
    },
    {
        "anchor": "Coherent Potential Approximation as a Voltage Probe: Coherent potential approximation (CPA) has widely been used for studying\nresidual resistivity of bulk alloys and electrical conductivity in\ninhomogeneous systems with structural disorder. Here we revisit the single-site\nCPA within the Landauer-B\\\"uttiker approach applied to the electronic transport\nin layered structures and show that this method can be interpreted in terms of\nthe B\\\"uttiker's voltage-probe model that has been developed for treating phase\nbreaking scattering in mesoscopic systems. We demonstrate that the on-site\nvertex function which appears within the single-site CPA formalism plays a role\nof the local chemical potential within the voltage-probe approach. This\ninterpretation allows the determination of the chemical potential profile\nacross a disordered conductor which is useful for analyzing results of\ntransport calculations within the CPA. We illustrate this method by providing\nseveral examples. In particular, for layered systems with translational\nperiodicity in the plane of the layers we introduce the local resistivity and\ncalculate the interface resistance between disordered layers.",
        "positive": "Scaling at the chaos threshold in an interacting quantum dot: The chaotic mixing by random two-body interactions of many-electron Fock\nstates in a confined geometry is investigated numerically and compared with\nanalytical predictions. Two distinct regimes are found in the dependence of the\ninverse participation ratio in Fock space I on the dimensionless conductance of\nthe quantum dot g and the excitation energy E. In both regimes I>>1, but only\nthe small-g regime is described by the golden rule. The crossover region is\ncharacterized by a maximum in a scaling function that becomes more pronounced\nwith increasing excitation energy. The scaling parameter that governs the\ntransition is (E/g)ln g."
    },
    {
        "anchor": "Floquet Engineering of Nonequilibrium Valley-Polarized Quantum Anomalous\n  Hall Effect with Tunable Chern Number: Numerous attempts have been made so far to explore the quantum anomalous Hall\neffect (QAHE), but the ultralow observed temperature strongly hinders its\npractical applications. Hence, it is of great interest to go beyond the\nexisting paradigm of QAHE. Here, we propose that Floquet engineering offers a\nstrategy to realize the QAHE via hybridization of Floquet-Bloch bands. Based on\nfirst-principles calculations and Floquet theorem, we unveil that\nnonequilibrium valley-polarized QAHE (VP-QAHE), independent of magnetic orders,\nis widely present in ferromagnetic and nonmagnetic members of two-dimensional\nfamily materials $M$Si$_2$$Z_4$ ($M$ = Mo, W, V; $Z$ = N, P, As) by irradiating\ncircularly polarized light (CPL). Remarkably, by tuning the frequency,\nintensity, and handedness of incident CPL, the Chern number of VP-QAHE is\nhighly tunable and up to $\\mathcal{C}=\\pm 4$. We reveal that such Chern number\ntunable VP-QAHE attributes to light-induced trigonal warping and multiple band\ninversion at different valleys. The valley-resolved chiral edge states and\nquantized plateau of Hall conductance, which facilitates the experimental\nmeasurement, are visible inside the global band gap. Our work not only\nestablishes Floquet Engineering of nonequilibrium VP-QAHE with tunable Chern\nnumber in realistic materials, but also provides a promising avenue to explore\nemergent topological phases under light irradiation.",
        "positive": "Tuning the ferro- to para-electric transition temperature and dipole\n  orientation of group-IV monochalcogenide monolayers: Coordination-related, two-dimensional (2D) structural phase transitions are a\nfascinating and novel facet of two-dimensional materials with structural\ndegeneracies. Nevertheless, a unified theoretical account of these transitions\nremains absent, and the following points are established through {\\em\nab-initio} molecular dynamics and 2D discrete clock models here: Group-IV\nmonochalcogenide (GeSe, SnSe, SnTe, ...) monolayers have four degenerate\nstructural ground states, and a 2D phase transition from a three-fold\ncoordinated onto a five-fold coordinated structure takes place at finite\ntemperature. On unstrained samples, the 2D phase transition requires lattice\nparameters to freely evolve. A fundamental energy scale permits understanding\nthis transition. The transition temperature $T_c$ and the orientation of the\nin-plane intrinsic electric dipole can be controlled by moderate uniaxial\ntensile strain, and a modified discrete clock model describes the transition on\nstrained samples. These results establish a general underlying theoretical\nbackground to understand structural phase transitions in 2D materials and their\neffects on material properties."
    },
    {
        "anchor": "Universal Behavior of Strain in Quantum Dots: Self-assembled quantum dots (QDs) are highly strained heterostructures. the\nlattice strain significantly modifies the electronic and optical properties of\nthese devices. A universal behavior is observed in atomistic strain simulations\n(in terms of both strain magnitude and profile) of QDs with different shapes\nand materials. In this paper, this universal behavior is investigated by\natomistic as well as analytic continuum models. Atomistic strain simulations\nare very accurate but computationally expensive. On the other hand, analytic\ncontinuum solutions are based on assumptions that significantly reduce the\naccuracy of the strain calculations, but are very fast. Both techniques\nindicate that the strain depends on the aspect ratio (AR) of the QDs, and not\non the individual dimensions. Thus simple closed form equations are introduced\nwhich directly provide the atomistic strain values inside the QD as a function\nof the AR and the material parameters. Moreover, the conduction and valence\nband edges $E_{C/V}$ and their effective masses $m^*_{C/V}$ of the QDs are\ndictated by the strain and AR consequently. The universal dependence of\natomistic strain on the AR is useful in many ways; Not only does it reduce the\ncomputational cost of atomistic simulations significantly, but it also provides\ninformation about the optical transitions of QDs given the knowledge of\n$E_{C/V}$ and $m^*_{C/V}$ from AR. Finally, these expressions are used to\ncalculate optical transition wavelengths in InAs/GaAs QDs and the results agree\nwell with experimental measurements and atomistic simulations.",
        "positive": "Ballistic spin-polarized transport and Rashba spin precession in\n  semiconductor nanowires: We present numerical calculations of the ballistic spin-transport properties\nof quasi-one-dimensional wires in the presence of the spin-orbit (Rashba)\ninteraction. A tight-binding analog of the Rashba Hamiltonian which models the\nRashba effect is used. By varying the robustness of the Rashba coupling and the\nwidth of the wire, weak and strong coupling regimes are identified. Perfect\nelectron spin-modulation is found for the former regime, regardless of the\nincident Fermi energy and mode number. In the latter however, the\nspin-conductance has a strong energy dependence due to a nontrivial subband\nintermixing induced by the strong Rashba coupling. This would imply a strong\nsuppression of the spin-modulation at higher temperatures and source-drain\nvoltages. The results may be of relevance for the implementation of\nquasi-one-dimensional spin transistor devices."
    },
    {
        "anchor": "Realizing Majorana Kramers pairs in two-channel InAs-Al nanowires with\n  highly misaligned electric fields: Common proposals for realizing topological superconductivity and Majorana\nzero modes in semiconductor-superconductor hybrids require large magnetic\nfields, which paradoxically suppress the superconducting gap of the parent\nsuperconductor. Although two-channel schemes have been proposed as a way to\neliminate magnetic fields, geometric constraints make their implementation\nchallenging, since the channels should be immersed in nearly antiparallel\nelectric fields. Here, we propose an experimentally favorable scheme for\nrealizing field-free topological superconductivity, in two-channel InAs-Al\nnanowires, that overcomes such growth constraints. Crucially, we show that\nantiparallel fields are not required, if the channels are energetically\ndetuned. We compute topological phase diagrams for realistically modeled\nnanowires, finding a broad range of parameters that could potentially harbor\nMajorana zero modes. This work, therefore, solves a major technical challenge\nand opens the door to near-term experiments.",
        "positive": "Charge-Relaxation and Dwell Time in the fluctuating Admittance of a\n  Chaotic Cavity: We consider the admittance of a chaotic quantum dot, capacitively coupled to\na gate and connected to two electron reservoirs by multichannel ballistic point\ncontacts. For a dot in the regime of weak-localization and universal\nconductance fluctuations, we calculate the average and variance of the\nadmittance using random-matrix theory. We find that the admittance is governed\nby two time-scales: the classical admittance depends on the RC-time of the\nquantum dot, but the relevant time scale for the weak-localization correction\nand the admittance fluctuations is the dwell time. An extension of the circular\nensemble is used for a statistical description of the energy dependence of the\nscattering matrix."
    },
    {
        "anchor": "Magnetization of Two Dimensional Heavy Holes with Boundaries in a\n  Perpendicular Magnetic Field: The magnetization of heavy holes in III-V semiconductor quantum wells with\nRashba spin-orbit coupling (SOC) in an external perpendicular magnetic field is\ntheoretically studied. We concentrate on the effects on the magnetization\ninduced by the system boundary, the Rashba SOC and the temperature. It is found\nthat the sawtooth-like de Haas--van Alphen (dHvA) oscillations of the\nmagnetization will change dramatically in the presence of such three factors.\nEspecially, the effects of the edge states and Rashba SOC on the magnetization\nare more evident when the magnetic field is more small. The oscillation center\nwill shift when the boundary effect is considered and the Rashba SOC will bring\nbeating patterns to the dHvA oscillations. These effects on the dHvA\noscillations are preferred to be observed at low temperature. With increasing\nthe temperature, the dHvA oscillations turn to be blurred and eventually\ndisappear.",
        "positive": "Effect of disorder on 2D topological merging transition from a Dirac\n  semi-metal to a normal insulator: We study the influence of disorder on the topological transition from a\ntwo-dimensional Dirac semi-metal to an insulating state. This transition is\ndescribed as a continuous merging of two Dirac points leading to a semi-Dirac\nspectrum at the critical point. The latter is characterized by a dispersion\nrelation linear in one direction and quadratic in the orthogonal one. Using the\nself-consistent Born approximation and renormalization group we calculate the\ndensity of states above, below and in the vicinity of the transition in the\npresence of different types of disorder. Beyond the expected disorder smearing\nof the transition we find an intermediate disordered semi-Dirac phase. On one\nside this phase is separated from the insulating state by a continuous\ntransition while on the other side it evolves through a crossover to the\ndisordered Dirac phase."
    },
    {
        "anchor": "Boundary scattering effects on magnetotransport of narrow metallic wires\n  and films: Electron transport in thin metallic wires and films is strongly influenced by\nthe quality of their surface. Weak localization and magnetoconductivity are\nalso sensitive to the electron scattering at the edges of the sample. We study\nweak localization effects in a two-dimensional electron gas patterned in the\nform of a narrow quasi-one-dimensional channel in transverse magnetic field.\nThe most general boundary conditions interpolating between the limits of mirror\nand diffuse edge scattering are assumed. We calculate magnetoconductivity for\nan arbitrary width of the sample including the cases of diffusive and ballistic\nlateral transport as well as the crossover between them. We find that in a\nbroad range of parameters, the electron mobility is limited by the boundary\nroughness while the magnetotransport is only weakly influenced by the quality\nof the edges. In addition, we calculate magnetoconductivity for a metallic\ncylinder in the transverse field and a quasi-two-dimensional metallic film in\nthe parallel field.",
        "positive": "Photoluminescence Blinking beyond Quantum-Confinement: Spatiotemporally\n  Correlated Intermittency over Entire Micron Sized Perovskite Polycrystalline\n  Disks: Abrupt fluorescence intermittency or blinking is long recognized to be\ncharacteristic of single nano-emitters. Extended quantum-confined\nnanostructures also undergo spatially heterogeneous blinking, however, there is\nno such precedence in dimensionally unconfined (bulk) materials. Here, we\nreport multi-level blinking of entire individual organo-lead bromide perovskite\nmicro-crystals (volume 0.1-3 micron-cuble) under ambient conditions. Extremely\nhigh spatiotemporal correlation (>0.9) in intra-crystal emission intensity\nfluctuations signifies effective communication amongst photogenerated carriers\nat distal locations (up to ~4 microns) within each crystal. Fused\npolycrystalline grains also exhibit this intriguing phenomenon, which is\nrationalized by correlated and efficient migration of carriers to a few\ntransient non-radiative traps, the nature and population of which determine\nblinking propensity. Observation of spatiotemporally correlated emission\nintermittency in bulk semiconductor crystals opens up the possibility to design\nnovel devices involving long range (mesoscopic) electronic communication."
    },
    {
        "anchor": "Screening Behavior and Scaling Exponents from Quantum Hall Wavefunctions: We provide a robust and generic method to assess the screening properties and\nextract the scaling exponents of quasiparticle edge excitations of quantum Hall\nstates from model wavefunctions. We numerically implement this method for the\nfundamental quasihole and hole excitations of several model states. For the\nLaughlin, Moore-Read, and Z_3-Read-Rezayi states, we find agreement with the\npredicted edge theory, verifying the bulk-edge correspondence. We also use this\nto obtain the first clear microscopic demonstration of the pathologies of the\nGaffnian wavefunctions.",
        "positive": "Thermoelectric Performance of various Benzo-difuran Wires: Using a first principles approach to electron transport, we calculate the\nelectrical and thermoelectrical transport properties of a series of molecular\nwires containing benzo-difuran subunits. We demonstrate that the side groups\nintroduce Fano resonances, the energy of which is changing with the\nelectronegativity of selected atoms in it. We also study the relative effect of\nsingle, double or triple bonds along the molecular backbone and find that\nsingle bonds yield the highest thermopower, approximately 22$\\mu$V/K at room\ntemperature, which is comparable with the highest measured values for\nsingle-molecule thermopower reported to date."
    },
    {
        "anchor": "Metastable quasi-one-dimensional ensembles of nitrogen clusters N_8: By means of ab initio and tight-binding calculations it is shown that\nmetastable nitrogen clusters N_8 (boats) can form quasi-one-dimensional\nensembles in which the nearest clusters N_8 are bound to each other by covalent\nbonds. Those ensembles are characterized by rather high energy barriers (~ 0.3\neV) that prevent the fission of the ensembles into isolated N_8 clusters and/or\nN_2 molecules.",
        "positive": "Electrical detection of magnon-photon interaction via auxiliary spin\n  wave mode: We report on the electrical detection of a hybrid magnon-photon system, which\nis comprised of a magnetic sample coupled to a planar cavity. While the uniform\nKittel mode has the largest coupling strength among all the magnon modes, it\nonly generates a modest voltage signal by means of inverse spin-Hall effect. We\nhave found that the generated voltage can be significantly enhanced by\nintroducing a higher order magnon mode, which possesses a much higher spin\npumping efficiency and furthermore, it is nearly degenerated with the Kittel\nmode. The experimental results can be explained by our theoretical model, and\nsuggest that the use of an auxiliary magnon mode can realize the configuration\nof a magnon-photon system with both strong coupling and large spin current."
    },
    {
        "anchor": "Nano patterns self-aligned to Ga dimer rows on GaAs surfaces: Ion beam irradiation of semiconductors is a method to produce regular\nperiodic nanoscale patterns self-organized on wafer scale. At low temperatures,\nthe surface of semiconductors is typically amorphized by the ion beam. Above a\nmaterial dependent dynamic recrystallization temperature however, the surface\nremains crystalline and ion beam irradiation produces regular arrays of faceted\nripples on III-V semiconductors. This provides a powerful single-step technique\nfor the production of nanostructures on a large area. On $(001)$ surfaces these\nripples are parallel to the $[1\\bar{1}0]$ direction without any external\nanisotropy. The origin of this self-alignment was not fully understood until\nnow. A simple experiment exposing the front side and back side of a GaAs$(001)$\nwafer to the ion beam clarifies its origin and proves that the ripples align to\nthe Ga dimer rows. As the direction of Ga dimer rows rotates by 90{\\deg} on the\nback side, the orientation of the ripples also rotates by 90{\\deg} to $[110]$.\nWe discuss the experimental results in view of a model where the pattern\nformation is driven by creation of vacancies and ad-atoms by the ion beam and\ntheir diffusion, which is linked to the direction of dimers on the surface.",
        "positive": "Bulk-edge correspondence in the trimer Su-Schrieffer-Heeger model: A remarkable feature of the trimer Su-Schrieffer-Heeger (SSH3) model is that\nit supports localized edge states. Although Zak's phase remains quantized for\nthe case of a mirror-symmetric chain, it is known that it fails to take integer\nvalues in the absence of this symmetry and thus it cannot play the role of a\nwell-defined bulk invariant in the general case. Attempts to establish a\nbulk-edge correspondence have been made via Green's functions or through\nextensions to a synthetic dimension. Here we propose a simple alternative for\nSSH3, utilizing the previously introduced sublattice Zak's phase, which also\nremains valid in the absence of mirror symmetry and for non-commensurate\nchains. The defined bulk quantity takes integer values, is gauge invariant, and\ncan be interpreted as the difference of the number of edge states between a\nreference and a target Hamiltonian. Our derivation further predicts the exact\ncorrections for finite open chains, is straightforwadly generalizable, and\ninvokes a chiral-like symmetry present in this model."
    },
    {
        "anchor": "A Unified Phonon Interpretation for the Non-Fourier Heat Conduction by\n  Non-equilibrium Molecular Dynamics Simulations: Nanoconfinement induces many intriguing non-Fourier heat conduction phenomena\nthat have been extensively studied in recent years, such as the nonlinear\ntemperature profile inside the devices, the temperature jumps near the\ncontacts, and the finite-size effects. The understanding of these phenomena,\nhowever, has been a matter of debate over the past two decades. In this work,\nwe demonstrate a unified phonon interpretation of non-Fourier heat conduction\nwhich can help to understand these phenomena by a mode-to-mode correspondence\nbetween the non-equilibrium molecular dynamics (NEMD) simulations and the\nmode-resolved phonon Boltzmann transport equation (BTE). It is found that the\nnanoscale phonon transport characteristics including temperature profile, the\nheat flux value and the modal temperature depend on the applied thermal\nreservoirs on the two contacts. Our NEMD simulations demonstrate that Langevin\nthermostat behaves like an infinitely large thermal reservoir and provides\nthermally equilibrium mode-resolved phonon outlets, while biased reservoirs,\ne.g., Nose-Hoover chain thermostat and velocity rescaling method behave like\nnon-equilibrium phonon outlets. Our interpretation clearly demonstrates that\nthe non-Fourier heat transport phenomena are originated from a combination of\nnon-diffusive phonon transport and phonon thermal nonequilibrium. This work\nprovides a clear understanding of nanoscale heat transport and may guide the\nmeasurement and control of thermal transport in various applications.",
        "positive": "Non-Hermitian Lindhard function and Friedel oscillations: The Lindhard function represents the basic building block of many-body\nphysics and accounts for charge response, plasmons, screening, Friedel\noscillation, RKKY interaction etc. Here we study its non-Hermitian version in\none dimension, where quantum effects are traditionally enhanced due to spatial\nconfinement, and analyze its behavior in various limits of interest. Most\nimportantly, we find that the static limit of the non-Hermitian Lindhard\nfunction has no divergence at twice the Fermi wavenumber and vanishes\nidentically for all other wavenumbers at zero temperature. Consequently, no\nFriedel oscillations are induced by a non-Hermitian, imaginary impurity to\nlowest order in the impurity potential at zero temperature. Our findings are\ncorroborated numerically on a tight-binding ring by switching on a weak real or\nimaginary potential. We identify conventional Friedel oscillations or heavily\nsuppressed density response, respectively."
    },
    {
        "anchor": "Thermal generation, manipulation and detection of skyrmions: Recent years have witnessed significant progresses in realizing skyrmions in\nchiral magnets1-4 and asymmetric magnetic multilayers5-13, as well as their\nelectrical manipulation2,7,8,10. Equally important, thermal generation,\nmanipulation and detection of skyrmions can be exploited for prototypical new\narchitecture with integrated computation14 and energy harvesting15. It has yet\nto verify if skyrmions can be purely generated by heating16,17, and if their\nresultant direction of motion driven by temperature gradients follows the\ndiffusion or, oppositely, the magnonic spin torque17-21. Here, we address these\nimportant issues in microstructured devices made of multilayers:\n(Ta_CoFeB_MgO)15, (Pt_CoFeB_MgO_Ta)15 and (Pt_Co_Ta)15 integrated with on-chip\nheaters, by using a full-field soft X-ray microscopy. The thermal generation of\ndensely packed skyrmions is attributed to the low energy barrier at the device\nedge, together with the thermally induced morphological transition from stripe\ndomains to skyrmions. The unidirectional diffusion of skyrmions from the hot\nregion towards the cold region is experimentally observed. It can be\ntheoretically explained by the combined contribution from repulsive forces\nbetween skyrmions, and thermal spin-orbit torques in competing with magnonic\nspin torques17,18,20,21 and entropic forces22. These thermally generated\nskyrmions can be further electrically detected by measuring the accompanied\nanomalous Nernst voltages23. The on-chip thermoelectric generation,\nmanipulation and detection of skyrmions could open another exciting avenue for\nenabling skyrmionics, and promote interdisciplinary studies among spin\ncaloritronics15, magnonics24 and skyrmionics3,4,12.",
        "positive": "On/off switching of bit readout in bias-enhanced tunnel magneto-Seebeck\n  effect: Thermoelectric effects in magnetic tunnel junctions are currently an\nattractive research topic. Here, we demonstrate that the tunnel magneto-Seebeck\neffect (TMS) in CoFeB/MgO/CoFeB tunnel junctions can be switched on to a logic\n1 state and off to 0 by simply changing the magnetic state of the CoFeB\nelectrodes. We enable this new functionality of magnetic tunnel junctions by\ncombining a thermal gradient and an electric field. This new technique unveils\nthe bias-enhanced tunnel magneto-Seebeck effect, which can serve as the basis\nfor logic devices or memories in a green information technology with a pure\nthermal write and read process. Furthermore, the thermally generated voltages\nthat are referred to as the Seebeck effect are well known to sensitively depend\non the electronic structure and therefore have been valued in solid-state\nphysics for nearly one hundred years. Here, we lift Seebeck's historic\ndiscovery from 1821 to a new level of current spintronics. Our results show\nthat the signal crosses zero and can be adjusted by tuning a bias voltage that\nis applied between the electrodes of the junction; hence, the name of the\neffect is bias-enhanced tunnel magneto-Seebeck effect (bTMS). Via the spin- and\nenergy-dependent transmission of electrons in the junction, the bTMS effect can\nbe configured using the bias voltage with much higher control than the tunnel\nmagnetoresistance (TMR) and even completely suppressed for only one magnetic\nconfiguration, which is either parallel (P) or anti-parallel (AP). This option\nallows a readout contrast for the magnetic information of -3000% at room\ntemperature while maintaining a large signal for one magnetic orientation. This\ncontrast is much larger than the value that can be obtained using the TMR\neffect. Moreover, our measurements are a step towards the experimental\nrealization of high TMS ratios, which are predicted for specific Co-Fe\ncompositions."
    },
    {
        "anchor": "Large flux-mediated coupling in hybrid electromechanical system with a\n  transmon qubit: Control over the quantum states of a massive oscillator is important for\nseveral technological applications and to test the fundamental limits of\nquantum mechanics. Addition of an internal degree of freedom to the oscillator\ncould be a valuable resource for such control. Recently, hybrid\nelectromechanical systems using superconducting qubits, based on\nelectric-charge mediated coupling, have been quite successful. Here, we realize\na hybrid device, consisting of a superconducting transmon qubit and a\nmechanical resonator coupled using the magnetic-flux. The coupling stems from\nthe quantum-interference of the superconducting phase across the tunnel\njunctions. We demonstrate a vacuum electromechanical coupling rate up to 4 kHz\nby making the transmon qubit resonant with the readout cavity. Consequently,\nthermal-motion of the mechanical resonator is detected by driving the\nhybridized-mode with mean-occupancy well below one photon. By tuning qubit away\nfrom the cavity, electromechanical coupling can be enhanced to 40 kHz. In this\nlimit, a small coherent drive on the mechanical resonator results in the\nsplitting of qubit spectrum, and we observe interference signature arising from\nthe Landau-Zener-St\\\"uckelberg effect. With improvements in qubit coherence,\nthis system offers a novel platform to realize rich interactions and could\npotentially provide full control over the quantum motional states.",
        "positive": "Stark effect and generalized Bloch-Siegert shift in a strongly driven\n  two-level system: A superconducting qubit was driven in an ultrastrong fashion by an\noscillatory microwave field, which was created by coupling via the nonlinear\nJosephson energy. The observed Stark shifts of the `atomic' levels are so\npronounced that corrections even beyond the lowest-order Bloch-Siegert shift\nare needed to properly explain the measurements. The quasienergies of the\ndressed two-level system were probed by resonant absorption via a cavity, and\nthe results are in agreement with a calculation based on the Floquet approach."
    },
    {
        "anchor": "The granularity effect in amorphous InGaZnO$_4$ films prepared by rf\n  sputtering method: We systematically investigated the temperature behaviors of the electrical\nconductivity and Hall coefficient of two series of amorphous indium gallium\nzinc oxides (a-IGZO) films prepared by rf sputtering method. The two series of\nfilms are $\\sim$700\\,nm and $\\sim$25\\,nm thick, respectively. For each film,\nthe conductivity increases with decreasing temperature from 300\\,K to $T_{\\rm\nmax}$, where $T_{\\rm max}$ is the temperature at which the conductivity reaches\nits maximum. Below $T_{\\rm max}$, the conductivity decreases with decreasing\ntemperature. Both the conductivity and Hall coefficient vary linearly with $\\ln\nT$ at low temperature regime. The $\\ln T$ behaviors of conductivity and Hall\ncoefficient cannot be explained by the traditional electron-electron\ninteraction theory, but can be quantitatively described by the current\nelectron-electron theory due to the presence of granularity. Combining with the\nscanning electron microscopy images of the films, we propose that the\nboundaries between the neighboring a-IGZO particles could make the film\ninhomogeneous and play an important role in the electron transport processes.",
        "positive": "High-precision real-space simulation of electrostatically-confined\n  few-electron states: In this paper we present a computational procedure that utilizes real-space\ngrids to obtain high precision approximations of electrostatically confined\nfew-electron states such as those that arise in gated semiconductor quantum\ndots. We use the Full Configuration Interaction (FCI) method with a\ncontinuously adapted orthonormal orbital basis to approximate the ground and\nexcited states of such systems. We also introduce a benchmark problem based on\na realistic analytical electrostatic potential for quantum dot devices. We show\nthat our approach leads to highly precise computed energies and energy\ndifferences over a wide range of model parameters. The analytic definition of\nthe benchmark allows for a collection of tests that are easily replicated, thus\nfacilitating comparisons with other computational approaches."
    },
    {
        "anchor": "Topological Insulators and C^*-Algebras: Theory and Numerical Practice: We apply ideas from $C^*$-algebra to the study of disordered topological\ninsulators. We extract certain almost commuting matrices from the free Fermi\nHamiltonian, describing band projected coordinate matrices. By considering\ntopological obstructions to approximating these matrices by exactly commuting\nmatrices, we are able to compute invariants quantifying different topological\nphases. We generalize previous two dimensional results to higher dimensions; we\ngive a general expression for the topological invariants for arbitrary\ndimension and several symmetry classes, including chiral symmetry classes, and\nwe present a detailed $K$-theory treatment of this expression for time reversal\ninvariant three dimensional systems. We can use these results to show\nnon-existence of localized Wannier functions for these systems.\n  We use this approach to calculate the index for time-reversal invariant\nsystems with spin-orbit scattering in three dimensions, on sizes up to $12^3$,\naveraging over a large number of samples. The results show an interesting\nseparation between the localization transition and the point at which the\naverage index (which can be viewed as an \"order parameter\" for the topological\ninsulator) begins to fluctuate from sample too sample, implying the existence\nof an unsuspected quantum phase transition separating two different delocalized\nphases in this system. One of the particular advantages of the $C^*$-algebraic\ntechnique that we present is that it is significantly faster in practice than\nother methods of computing the index, allowing the study of larger systems. In\nthis paper, we present a detailed discussion of numerical implementation of our\nmethod.",
        "positive": "Dirac-Schrodinger transformations in contacted graphene structures: At an interface between contacts and graphene, the mathematical equation that\ngoverns the propagation of electrons transforms from the Schrodinger to the\nDirac equation. The condition of current probability conservation at such an\ninterface does not determine uniquely the boundary conditions for the quantum\nwavefunction. We discuss the possible form of boundary conditions, determine\nits influence on the transmission coefficient of a contacted graphene structure\nand suggest that optical experiments on photonic crystals with Dirac points can\nhelp identifying, under certain circumstances, the proper boundary condition at\ngraphene- electrode interfaces."
    },
    {
        "anchor": "Dependence of the amplitude of magnetoquantum oscillations of the\n  metallic point-contact resistance on the bias voltage: Magnetoquantum oscillations of resistance as functions of the potential\ndifference applied across the contact are studied for metallic point contacts\nmade of $Al$ and $Be$. The amplitude of resistance oscillations in a magnetic\nfield increases with voltage and is identical to the EPI spectrum of the point\ncontact for one group of contacts, and with the bias voltage across the contact\nfor another. The increase in the oscillation amplitude as well as its decrease\nhas a nonmonotonic dependence on energy. The scattering of electrons by\nnonequilibrium phonons and the Fermi-liquid effects in the nonequilibrium\nelectron system are considered as the possible reasons behind the observed\neffects.",
        "positive": "New Dirac points and multiple Landau level crossings in biased trilayer\n  graphene: Recently a new high-mobility Dirac material, trilayer graphene, was realized\nexperimentally. The band structure of ABA-stacked trilayer graphene consists of\na monolayer-like and a bilayer-like pairs of bands. Here we study electronic\nproperties of ABA-stacked trilayer graphene biased by a perpendicular electric\nfield. We find that the combination of the bias and trigonal warping gives rise\nto a set of new Dirac points: in each valley, seven species of Dirac fermions\nwith small masses of order of a few meV emerge. The positions and masses of the\nemergent Dirac fermions are tunable by bias, and one group of Dirac fermions\nbecomes massless at a certain bias value. Therefore, in contrast to bilayer\ngraphene, the conductivity at the neutrality point is expected to show\nnon-monotonic behavior, becoming of the order of a few e^2/h when some Dirac\nmasses vanish. Further, we analyze the evolution of Landau level spectrum as a\nfunction of bias. Emergence of new Dirac points in the band structure\ntranslates into new three-fold-degenerate groups of Landau levels. This leads\nto an anomalous quantum Hall effect, in which some quantum Hall steps have a\nheight of 3e^2/h. At an intermediate bias, the degeneracies of all Landau\nlevels get lifted, and in this regime all quantum Hall plateaus are spaced by\ne^2/h. Finally, we show that the pattern of Landau level crossings is very\nsensitive to certain band structure parameters, and can therefore provide a\nuseful tool for determining their precise values."
    },
    {
        "anchor": "Edge states and skyrmion dynamics in nanostripes of frustrated magnets: Magnetic skyrmions are particle-like topological excitations recently\ndiscovered in chiral magnets. Their small size, topological protection and the\nease with which they can be manipulated by electric currents generated much\ninterest in using skyrmions for information storage and processing. Recently,\nit was suggested that skyrmions with additional degrees of freedom can exist in\nmagnetically frustrated materials. Here, we show that dynamics of skyrmions and\nantiskyrmions in nanostripes of frustrated magnets is strongly affected by\ncomplex spin states formed at the stripe edges. These states create multiple\nedge channels which guide the skyrmion motion. Non-trivial topology of edge\nstates gives rise to complex current-induced dynamics, such as emission of\nskyrmion-antiskyrmion pairs. The edge state topology can be controlled with an\nelectric current through the exchange of skyrmions and antiskyrmions between\nthe edges of a magnetic nanostructure. These results can lead to conceptually\nnew electronic devices.",
        "positive": "Spin polarization of the $\u03bd=5/2$ quantum Hall state: We report on results of numerical studies of the spin polarization of the\nhalf filled second Landau level, which corresponds to the fractional quantum\nHall state at filling factor $\\nu=5/2$. Our studies are performed using both\nexact diagonalization and Density Matrix Renormalization Group (DMRG) on the\nsphere. We find that for the Coulomb interaction the exact finite-system ground\nstate is fully polarized, for shifts corresponding to both the Moore-Read\nPfaffian state and its particle-hole conjugate (anti-Pfaffian). This result is\nfound to be robust against small variations of the interaction. The low-energy\nexcitation spectrum is consistent with spin-wave excitations of a\nfully-magnetized ferromagnet."
    },
    {
        "anchor": "Hot spot-mediated non-dissipative and ultrafast plasmon passage: Plasmonic nanoparticles hold great promise as photon handling elements and as\nchannels for coherent transfer of energy and information in future all-optical\ncomputing devices. Coherent energy oscillations between two spatially separated\nplasmonic entities via a virtual middle state exemplify electron-based\npopulation transfer, but their realization requires precise nanoscale\npositioning of heterogeneous particles. Here, we show the assembly and optical\nanalysis of a triple particle system consisting of two gold nanoparticles with\nan inter-spaced silver island. We observe strong plasmonic coupling between the\nspatially separated gold particles mediated by the connecting silver particle\nwith almost no dissipation of energy. As the excitation energy of the silver\nisland exceeds that of the gold particles, only quasi-occupation of the silver\ntransfer channel is possible. We describe this effect both with exact classical\nelectrodynamic modeling and qualitative quantum-mechanical calculations. We\nidentify the formation of strong hot spots between all particles as the main\nmechanism for the loss-less coupling and thus coherent ultra-fast energy\ntransfer between the remote partners. Our findings could prove useful for\nquantum gate operations, but also for classical charge and information transfer\nprocesses.",
        "positive": "Carrier relaxation in GaAs v-groove quantum wires and the effects of\n  localization: Carrier relaxation processes have been investigated in GaAs/AlGaAs v-groove\nquantum wires (QWRs) with a large subband separation (46 meV). Signatures of\ninhibited carrier relaxation mechanisms are seen in temperature-dependent\nphotoluminescence (PL) and photoluminescence-excitation (PLE) measurements; we\nobserve strong emission from the first excited state of the QWR below ~50 K.\nThis is attributed to reduced inter-subband relaxation via phonon scattering\nbetween localized states. Theoretical calculations and experimental results\nindicate that the pinch-off regions, which provide additional two-dimensional\nconfinement for the QWR structure, have a blocking effect on relaxation\nmechanisms for certain structures within the v-groove. Time-resolved PL\nmeasurements show that efficient carrier relaxation from excited QWR states\ninto the ground state, occurs only at temperatures > 30 K. Values for the low\ntemperature radiative lifetimes of the ground- and first excited-state excitons\nhave been obtained (340 ps and 160 ps respectively), and their corresponding\nlocalization lengths along the wire estimated."
    },
    {
        "anchor": "Dissipative and conservative nonlinearity in carbon nanotube and\n  graphene mechanical resonators: Graphene and carbon nanotubes represent the ultimate size limit of one and\ntwo-dimensional nanoelectromechanical resonators. Because of their reduced\ndimensionality, graphene and carbon nanotubes display unusual mechanical\nbehavior; in particular, their dynamics is highly nonlinear. Here, we review\nseveral types of nonlinear behavior in resonators made from nanotubes and\ngraphene. We first discuss an unprecedented scenario where damping is described\nby a nonlinear force. This scenario is supported by several experimental facts:\n(i) the quality factor varies with the amplitude of the motion as a power law\nwhose exponent coincides with the value predicted by the nonlinear damping\nmodel, (ii) hysteretic behavior (of the motional amplitude as a function of\ndriving frequency) is absent in some of our resonators even for large driving\nforces, as expected when nonlinear damping forces are large, and (iii) when we\nquantify the linear damping force (by performing parametric excitation\nmeasurements) we find that it is significantly smaller than the nonlinear\ndamping force. We then review parametric excitation measurements, an\nalternative actuation method which is based on nonlinear dynamics. Finally, we\ndiscuss experiments where the mechanical motion is coupled to electron\ntransport through a nanotube. The coupling can be made so strong that the\nassociated force acting on the nanotube becomes highly nonlinear with\ndisplacement and velocity. Overall, graphene and nanotube resonators hold\npromise for future studies on classical and quantum nonlinear dynamics.",
        "positive": "Reply to Comment on \"Quantum Coherence between High Spin Superposition\n  States of Single Molecule Magnet Ni$_4$\": Here we respond briefly to a comment on our work in arXiv:cond-mat/0405501."
    },
    {
        "anchor": "Majorana ensembles with fractional entropy and conductance in nanoscopic\n  systems: Quantum thermodynamics is a promising route to unambiguous detections of\nMajorana bound states. Being fundamentally different from quantum transport,\nthis approach reveals unique Majorana thermodynamic behavior and deepens our\ninsight into Majorana quantum transport itself. Here we demonstrate that a\nnanoscopic system with topological superconductors produces a remarkable\naccumulation of Majorana thermodynamic states in wide ranges of Majorana\ntunneling phases by means of increasing its temperature $T$. Revealing this\nphysical behavior is twofold beneficial. First, it significantly reduces the\ndependence of the entropy on the tunneling phases which become almost\nirrelevant in experiments. Second, the fractional Majorana entropy\n$S_M^{(2)}=k_B\\ln(2^\\frac{3}{2})$ may be observed at high temperatures\nsubstantially facilitating experiments. Analyzing quantum transport, we predict\nthat when the temperature increases, the above thermodynamic behavior will\ninduce an anomalous increase of the linear conductance from vanishing values up\nto the unitary fractional Majorana plateau $G_M=e^2/2h$ extending to high\ntemperatures.",
        "positive": "Magnetic spin imaging under ambient conditions with sub-cellular\n  resolution: Measuring spins is the corner stone of a variety of analytical techniques\nincluding modern magnetic resonance imaging (MRI). The full potential of spin\nimaging and sensing across length scales is hindered by the achievable\nsignal-to-noise in inductive detection schemes. Here we show that a proximal\nNitrogen-Vacancy (NV) ensemble serves as a precision sensing array. Monitoring\nits quantum relaxation enables sensing of freely diffusing and unperturbed\nmagnetic ions in a microfluidic device. Multiplexed CCD acquisition and an\noptimized detection scheme enable direct spin noise imaging under ambient\nconditions with experimental sensitivities down to 1000 statistically polarized\nspins, of which only 35 ions contribute to a net magnetization, and 20 s\nacquisition time. We also demonstrate imaging of spin labeled cellular\nstructures with spatial resolutions below 500 nm. Our study marks a major step\ntowards sub-{\\mu}m imaging magnetometry and applications in microanalytics,\nmaterial and life sciences."
    },
    {
        "anchor": "Insulators at Fractional Fillings in Twisted Bilayer Graphene Partially\n  Aligned to Hexagonal Boron Nitride: At partial fillings of its flat electronic bands, magic-angle twisted bilayer\ngraphene (MATBG) hosts a rich variety of competing correlated phases that show\nsample to sample variations. Divergent phase diagrams in MATBG are often\nattributed to the sublattice polarization energy scale, tuned by the degree of\nalignment of the hexagonal boron nitride (hBN) substrates typically used in van\nder Waals devices. Unaligned MATBG exhibits unconventional superconductivity\nand correlated insulating phases, while nearly perfectly aligned MATBG/hBN\nexhibits zero-field Chern insulating phases and lacks superconductivity. Here\nwe use scanning tunneling microscopy and spectroscopy (STM/STS) to observe\ngapped phases at partial fillings of the flat bands of MATBG in a new\nintermediate regime of sublattice polarization, observed when MATBG is only\npartially aligned ($\\theta_{Gr-hBN}$ $\\approx$ 1.65$^\\circ$) to the underlying\nhBN substrate. Under this condition, MATBG hosts not only phenomena that\nnaturally interpolate between the two sublattice potential limits, but also\nunexpected gapped phases absent in either of these limits. At charge\nneutrality, we observe an insulating phase with a small energy gap ($\\Delta$ <\n5 meV) likely related to weak sublattice symmetry breaking from the hBN\nsubstrate. In addition, we observe new gapped phases near fractional fillings\n$\\nu$ = $\\pm 1/3$ and $\\nu$ = $\\pm 1/6$, which have not been previously\nobserved in MATBG. Importantly, energy-resolved STS unambiguously identifies\nthese fractional filling states to be of single-particle origin, possibly a\nresult of the super-superlattice formed by two moir\\'e superlattices. Our\nobservations emphasize the power of STS in distinguishing single-particle\ngapped phases from many-body gapped phases in situations that could be easily\nconfused in electrical transport measurements.",
        "positive": "Experimental analysis of the spin-orbit coupling dependence on the drift\n  velocity of a spin packet: Spin transport was studied in a two-dimensional electron gas hosted in a wide\nGaAs quantum well occupying two subbands. Using space and time Kerr rotation\nmicroscopy to image drifting spin packets under an in-plane accelerating\nelectric field, optical injection and detection of spin polarization were\nachieved in a pump-probe configuration. The experimental data exhibited high\nspin mobility and long spin lifetimes allowing to obtain the spin-orbit fields\nas a function of the spin velocities. Surprisingly, above moderate electric\nfields of 0.4V/cm with velocities higher than 2$\\mu$m/ns, we observed a\ndependence of both bulk and structure-related spin-orbit interactions on the\nvelocity magnitude. A remarkable feature is the increase of the cubic\nDresselhaus term to approximately half of the linear coupling when the velocity\nis raised to 10$\\mu$m/ns. In contrast, the Rashba coupling for both subbands\ndecreases to about half of its value in the same range. These results yield new\ninformation for the application of drift models in spin-orbit fields and about\nlimitations for the operation of spin transistors."
    },
    {
        "anchor": "Transport in two dimensional Rashba electron systems doped with\n  interacting magnetic impurities: We study the transport properties of two dimensional electron systems with\nstrong Rashba spin-orbit coupling (SOC) doped with interacting magnetic\nimpurities. Interactions between magnetic impurities cause the formation of\nmagnetic clusters with temperature dependent mean sizes (CMSs) distributed\nrandomly on the surface of the system. Treating magnetic clusters as scattering\ncenters, by employing a generalized relaxation time approximation we obtain the\nnon-equilibrium distribution functions of Rashba electrons in both regimes of\nabove and below the band-crossing point (BCP) and present the explicit forms of\nthe conductivity in terms of effective relaxation times. We demonstrate that\nthe combined effects of SOC and magnetic clusters cause the system to be\nanisotropic and the magneto-resistance strongly depends on both the clusters'\nmean size and spin, the strengths of SOC and the location of Fermi energy with\nrespect to the BCP. Our results show that there are many contrasts between the\ntransport properties of the system in the two regimes of above and below the\nBCP. By comparing the anisotropic magneto-resistance (AMR) of the two\ndimensional Rashba systems with the surface AMR of three dimensional magnetic\ntopological insulators, we also point out the differences between these\nsystems.",
        "positive": "Current-Driven Domain-Wall Dynamics in Curved Ferromagnetic Nanowires: The current-induced motion of a domain wall in a semicircle nanowire with\napplied Zeeman field is investigated. Starting from a micromagnetic model we\nderive an analytical solution which characterizes the domain-wall motion as a\nharmonic oscillation. This solution relates the micromagnetic material\nparameters with the dynamical characteristics of a harmonic oscillator, i.e.,\ndomain-wall mass, resonance frequency, damping constant, and force acting on\nthe wall. For wires with strong curvature the dipole moment of the wall as well\nas its geometry influence the eigenmodes of the oscillator. Based on these\nresults we suggest experiments for the determination of material parameters\nwhich otherwise are difficult to access. Numerical calculations confirm our\nanalytical solution and show its limitations."
    },
    {
        "anchor": "Negative Magnetoresistance and Spin Filtering of Spin-Coupled Diiron-Oxo\n  Clusters: Spin dependent transport has been investigated for an {\\it open shell\nsinglet} diiron-oxo cluster. Currents and magnetoresistances have been studied,\nas a function of spin state, within the non-equilibrium Green's function\napproach. The applied bias can be used for tuning the sign of the observed\nmagnetoresistance. A colossal magnetoresistance ratio has been determined, on\nthe order of to 6000$%$, for hydrogen anchoring. Applied biases lower than 0.3\nV, in conjunction with sulfur anchoring, induce a negative magnetoresistance\ndue to lowering of the anchor-scatterer tunneling barrier. In addition, the\ndiiron-oxo cluster displays nearly perfect spin filtering for parallel\nalignment of the iron magnetic moments due to energetic proximity, relative to\nthe Fermi level, of its highest occupied molecular orbitals.",
        "positive": "Electronic scattering off a magnetic hopfion: We study scattering of itinerant electrons off a magnetic hopfion in a\nthree-dimensional metallic magnet described by a magnetization vector $\\mathbf\nS(\\mathbf r)$. A hopfion is a confined topological soliton of $\\mathbf\nS(\\mathbf r)$ characterized by an {\\it emergent} magnetic field\n$B_\\gamma(\\mathbf r) \\equiv \\epsilon_{\\alpha\\beta\\gamma} \\,\\mathbf\nS\\cdot(\\nabla_\\alpha \\mathbf S\\times \\nabla_\\beta \\mathbf S)/4 \\neq 0$ with\nvanishing average value $\\langle \\mathbf B(\\mathbf r)\\rangle = 0$. We evaluate\nthe scattering amplitude in the opposite limits of large and small hopfion\nradius $R$ using the eikonal and Born approximations, respectively. In both\nlimits, we find that the scattering cross-section contains a skew-scattering\ncomponent giving rise to the Hall effect within a hopfion plane. That\nconclusion contests the popular notion that the topological Hall effect in\nnon-collinear magnetic structures necessarily implies $\\langle \\mathbf\nB(\\mathbf r)\\rangle \\neq 0$. In the limit of small hopfion radius $pR \\ll 1$,\nwe expand the Born series in powers of momentum $p$ and identify different\nexpansion terms corresponding to the hopfion anisotropy, toroidal moment, and\nskew-scattering."
    },
    {
        "anchor": "Spin-accumulation in small ferromagnetic double barrier junctions: The non-equilibrium spin accumulation in ferromagnetic double barrier\njunctions is shown to govern the transport in small structures. Transport\nproperties of such systems are described by a generalization of the theory of\nthe Coulomb blockade. The spin accumulation enhances the magnetoresistance. The\ntransient non-linear transport properties are predicted to provide a unique\nexperimental evidence of the spin-accumulation in the form of a reversed\ncurrent on time scales of the order of the spin-flip relaxation time.",
        "positive": "Efficient Gating of Magnons by Proximity Superconductors: Electrostatic gating confines and controls the transport of electrons in\nintegrated circuits. Magnons, the quanta of spin waves of the magnetic order,\nare promising alternative information carriers, but difficult to gate. Here we\nreport that superconducting strips on top of thin magnetic films can totally\nreflect magnons by its diamagnetic response to the magnon stray fields. The\ninduced large frequency shifts unidirectionally blocks the magnons propagating\nnormal to the magnetization. Two superconducting gates parallel to the\nmagnetization create a magnonic cavity. The option to gate coherent magnons\nadds functionalities to magnonic devices, such as reprogrammable logical\ndevices and increased couplings to other degrees of freedom."
    },
    {
        "anchor": "Quantum dynamics of optical phonons generated by optical excitation of a\n  quantum dot: The study of the fundamental properties of phonons is crucial to understand\ntheir role in applica- tions in quantum information science, where the active\nuse of phonons is currently highly debated. A genuine quantum phenomenon\nassociated with the fluctuation properties of phonons is squeezing, which is\nachieved when the fluctuations of a certain variable drop below their\nrespective vacuum value. We consider a semiconductor quantum dot in which the\nexciton is coupled to phonons. We review the fluctuation properties of the\nphonons, which are generated by optical manipulation of the quantum dot, in the\nlimiting case of ultra short pulses. Then we discuss the phonon properties for\nan excitation with finite pulses. Within a generating function formalism we\ncalculate the corre- sponding fluctuation properties of the phonons and show\nthat phonon squeezing can be achieved by the optical manipulation of the\nquantum dot exciton for certain conditions even for a single pulse excitation\nwhere neither for short nor for long pulses squeezing occurs. To explain the\noccurrence of squeezing we employ a Wigner function picture providing a\ndetailed understanding of the induced quantum dynamics.",
        "positive": "Electrical and optical studies of GaMnAs/GaAs(001) thin films grown by\n  molecular beam epitaxy: GaMnAs/GaAs films were grown via molecular beam epitaxy using both low and\nhigh substrate temperatures. The films were investigated using Hall effect and\nphotoluminescence (PL) measurements from 8 to 300 K. The carrier concentrations\nin the samples grown at a low substrate temperature are greater than those in\nthe samples grown at a high substrate temperature. The PL spectra show a GaAs\nexciton peak, a peak involving a carbon acceptor, a substitutional Mn\nacceptor-related peak and an optical phonon-related peak."
    },
    {
        "anchor": "Optimizing Topological Switching in Confined 2D-Xene Nanoribbons via\n  Finite-Size Effects: In a blueprint for topological electronics, edge state transport in a\ntopological insulator material can be controlled by employing a gate-induced\ntopological quantum phase transition. Here, by studying the width dependence of\nelectronic properties, it is inferred that zigzag-Xene nanoribbons are\npromising materials for topological electronics with a display of unique\nphysical characteristics associated with the intrinsic band topology and the\nfinite-size effects on gate-induced topological switching. First, due to\nintertwining with intrinsic band topology-driven energy-zero modes in the\npristine case, spin-filtered chiral edge states in zigzag-Xene nanoribbons\nremain gapless and protected against backward scattering even with finite\ninter-edge overlapping in ultra-narrow ribbons, i.e., a 2D quantum spin Hall\nmaterial turns into a 1D topological metal. Second, mainly due to width- and\nmomentum-dependent tunability of the gate-induced inter-edge coupling, the\nthreshold-voltage required for switching between gapless and gapped edge states\nreduces as the width decreases, without any fundamental lower bound. Third,\nwhen the width of zigzag-Xene nanoribbons is smaller than a critical limit,\ntopological switching between edge states can be attained without bulk bandgap\nclosing and reopening. This is primarily due to the quantum confinement effect\non the bulk band spectrum which increases the nontrivial bulk bandgap with\ndecrease in width. The existence of such protected gapless edge states and\nreduction in threshold-voltage accompanied by enhancement in the bulk bandgap\noverturns the general wisdom of utilizing narrow-gap and wide channel materials\nfor reducing the threshold-voltage in a standard field effect transistor\nanalysis and paves the way toward low-voltage topological devices.",
        "positive": "Stability of frozen waves in the Modified Cahn--Hilliard model: We examine the existence and stability of frozen waves in diblock copolymers\nwith local conservation of the order parameter, which are described by the\nmodified Cahn--Hilliard model. It is shown that a range of stable waves exists\nand each can emerge from a `general' initial condition (not only the one with\nthe lowest density of free energy). We discuss the implications of these\nresults for the use of block copolymers in templating nanostructures."
    },
    {
        "anchor": "Fano factor reduction on the 0.7 structure in a ballistic\n  one-dimensional wire: We have measured the non-equilibrium current noise in a\nballisticone-dimensional wire which exhibits an additional conductanceplateau\nat $0.7\\times2e^2/h$. The Fano factor shows a clearreduction on the 0.7\nstructure, and eventually vanishes uponapplying a strong parallel magnetic\nfield. These results provideexperimental evidence that the 0.7 structure is\nassociated withtwo conduction channels which have different\ntransmissionprobabilities.",
        "positive": "Time-resolved magnetophotoluminescence studies of magnetic polaron\n  dynamics in type-II quantum dots: We used continuous wave photoluminescence (cw-PL) and time resolved\nphotoluminescence (TR-PL) spectroscopy to compare the properties of magnetic\npolarons (MP) in two related spatially indirect II-VI epitaxially grown quantum\ndot systems. In the ZnTe/(Zn,Mn)Se system the holes are confined in the\nnon-magnetic ZnTe quantum dots (QDs), and the electrons reside in the magnetic\n(Zn,Mn)Se matrix. On the other hand, in the (Zn,Mn)Te/ZnSe system, the holes\nare confined in the magnetic (Zn,Mn)Te QDs, while the electrons remain in the\nsurrounding non-magnetic ZnSe matrix. The magnetic polaron formation energies\nin both systems were measured from the temporal red-shift of the band-edge\nemission. The magnetic polaron exhibits distinct characteristics depending on\nthe location of the Mn ions. In the ZnTe/(Zn,Mn)Se system the magnetic polaron\nshows conventional behavior with decreasing with increasing temperature T and\nincreasing magnetic field B. In contrast, in the (Zn,Mn)Te/ZnSe system has\nunconventional dependence on temperature T and magnetic field B; is weakly\ndependent on T as well as on B. We discuss a possible origin for such a\nstriking difference in the MP properties in two closely related QD systems."
    },
    {
        "anchor": "Electrically Sign-Reversible Topological Hall Effect in a Top-Gated\n  Topological Insulator (Bi,Sb)2Te3 on a Ferrimagnetic Insulator Europium Iron\n  Garnet: Topological Hall effect (THE), an electrical transport signature of systems\nwith chiral spin textures like skyrmions, has been observed recently in\ntopological insulator (TI)-based magnetic heterostructures. However, the\nintriguing interplay between the topological surface state and THE is yet to be\nfully understood. In this work, we report a large THE of ~10 ohm (~4\nmicro-ohm*cm) at 2 K with an electrically reversible sign in a top-gated 4 nm\nTI (Bi0.3Sb0.7)2Te3 (BST) grown on a ferrimagnetic insulator (FI) europium iron\ngarnet (EuIG). Temperature, external magnetic field angle, and top gate bias\ndependences of magnetotransport properties were investigated and consistent\nwith a skyrmion-driven THE. Most importantly, a sign change in THE was\ndiscovered as the Fermi level was tuned from the upper to the lower parts of\nthe gapped Dirac cone and vice versa. This discovery is anticipated to impact\ntechnological applications in ultralow power skyrmion-based spintronics.",
        "positive": "Conductance modulation in spin field-efect transistors under finite bias\n  voltages: The conductance modulations in spin field-effect transistors under finite\nbias voltages were studied. It was shown that when a finite bias voltage is\napplied between two terminals of a spin field-effect transistor, the spin\nprecession states of injected spin-polarized electrons in the semiconductor\nchannel of the device will depend not only the gate-voltage controlled Rashba\nspin-orbit coupling but also depend on the bias voltage and, hence, the\nconductance modulation in the device due to Rashba spin-orbit coupling may also\ndepend sensitively on the bias voltage."
    },
    {
        "anchor": "Extrinsic morphology of graphene: Graphene is intrinsically non-flat and corrugates randomly. Since the\ncorrugating physics of atomically-thin graphene is strongly tied to its\nelectronics properties, randomly corrugating morphology of graphene poses\nsignificant challenge to its application in nanoelectronic devices for which\nprecise (digital) control is the key. Recent studies revealed that the\nmorphology of substrate-supported graphene is regulated by the\ngraphene-substrate interaction, thus is distinct from the random intrinsic\nmorphology of freestanding graphene. The regulated extrinsic morphology of\ngraphene sheds light on new pathways to fine tune the properties of graphene.\nTo guide further research to explore these fertile opportunities, this paper\nreviews recent progress on modeling and experimental studies of the extrinsic\nmorphology of graphene under a wide range of external regulation, including two\ndimensional and one dimensional substrate surface features and one dimensional\nand zero dimensional nanoscale scaffolds (e.g., nanowires and nanoparticles).",
        "positive": "The higher-order magnetic skyrmions in non-uniform magnetic fields: For 2D Hubbard model with spin-orbit Rashba coupling in external magnetic\nfield the structure of effective spin interactions is studied in the regime of\nstrong electron correlations and at half-filling. It is shown that in the third\norder of perturbation theory, the scalar and vector chiral spin-spin\ninteractions of the same order arise. The emergence of the latter is due to\norbital effects of magnetic field. It is shown that for nonuniform fields,\nscalar chiral interaction can lead to stabilization of axially symmetric\nskyrmion states with arbitrary topological charges. Taking into account the\nhierarchy of effective spin interactions, an analytical theory on the optimal\nsizes of such states -- the higher-order magnetic skyrmions -- is developed for\naxially symmetric magnetic fields of the form $h(r) \\sim r^{\\beta}$ with $\\beta\n\\in \\mathbb{R}$."
    },
    {
        "anchor": "Robustness of the far-field response of nonlocal plasmonic ensembles: Contrary to classical predictions, the optical response of few-nm plasmonic\nparticles depends on particle size due to effects such as nonlocality and\nelectron spill-out. Ensembles of such nanoparticles (NPs) are therefore\nexpected to exhibit a nonclassical inhomogeneous spectral broadening due to\nsize distribution. For a normal distribution of free-electron NPs, and within\nthe simple nonlocal Hydrodynamic Drude Model (HDM), both the nonlocal blueshift\nand the plasmon linewidth are shown to be considerably affected by ensemble\naveraging. Size-variance effects tend however to conceal nonlocality to a\nlesser extent when the homogeneous size-dependent broadening of individual NPs\nis taken into account, either through a local size-dependent damping (SDD)\nmodel or through the Generalized Nonlocal Optical Response (GNOR) theory. The\nrole of ensemble averaging is further explored in realistic distributions of\nnoble-metal NPs, as encountered in experiments, while an analytical expression\nto evaluate the importance of inhomogeneous broadening through measurable\nquantities is developed. Our findings are independent of the specific\nnonclassical theory used, thus providing important insight into a large range\nof experiments on nanoscale and quantum plasmonics.",
        "positive": "Quantum confinement in Dirac-like nanostructures: In Westminster Abbey, in a nave near to Newton's monument, lies a memorial\nstone to Paul Dirac. The inscription on the stone includes the relativistic\nwave equation for an electron: the Dirac equation. At the turn of the 21st\ncentury, it was discovered that this eponymous equation was not simply the\npreserve of particle physics. The isolation of graphene by Andre Geim and\nKonstantin Novoselov in Manchester led to the exploration of a novel class of\nmaterials - Dirac materials - whose electrons behave like Dirac particles.\nWhile the mobility of these quasi-relativistic electrons is attractive from the\nperspective of potential ultrafast devices, it also presents a distinct\nchallenge: how to confine Dirac particles so as to avoid making inherently\nleaky devices? Here we discuss the unconventional quantum tunnelling of Dirac\nparticles, we explain a strategy to create bound states electrostatically, and\nwe briefly review some pioneering experiments seeking to trap Dirac electrons."
    },
    {
        "anchor": "Coherent ultrafast spin-dynamics probed in three dimensional topological\n  insulators: Topological insulators are candidates to open up a novel route in spin based\nelectronics. Different to traditional ferromagnetic materials, where the\ncarrier spin-polarization and magnetization are based on the exchange\ninteraction, the spin properties in topological insulators are based on the\ncoupling of spin- and orbit interaction connected to its momentum. Specific\nways to control the spin-polarization with light have been demonstrated: the\nenergy momentum landscape of the Dirac cone provides spin-momentum locking of\nthe charge current and its spin. The directionality of spin and momentum, as\nwell as control with light has been demonstrated. Here we demonstrate a\ncoherent femtosecond control of spin-polarization for states in the valence\nband at around the Dirac cone.",
        "positive": "Probing Magnetic and Triplet Correlations in Spin-Split Superconductors\n  with Magnetic Impurities: A superconductor (SC) in proximity to a ferromagnetic insulator (FMI) is\npredicted to exhibit mixed singlet and triplet pair correlations. The magnetic\nproximity effect of FMI spin-splits the energy of Bogoliubov excitations and\nleads to a spin polarization at the surface for superconducting films thinner\nthan the superconducting coherence length. In this work, we study\nmanifestations of these phenomena in the properties of a magnetic impurity\ncoupled via Kondo coupling to this FMI/SC system. Using the numerical\nrenormalization group (NRG) method, we compute the properties of the ground\nstate and low-lying excited states of a model that incorporates the Kondo\ninteraction and a Ruderman-Kittel-Kasuya-Yosida (RKKY)-like interaction with\nthe surface spin polarization. Our main finding is an energy splitting of the\nlowest even fermion-parity states caused by the proximity to the FMI. As the\nKondo coupling increases, the splitting grows and saturates to a universal\nvalue equal to twice the exchange field of the FMI. We introduce a two-site\nmodel that can be solved analytically and provides a qualitative understanding\nof this and other NRG results. In addition, using perturbation theory we\ndemonstrate that the mechanism behind the splitting involves the RKKY field and\nthe triplet correlations of the spin-split superconductor. A scaling analysis\ncombined with NRG shows that the splitting can be written as a single-parameter\nscaling function of the ratio of the Kondo temperature and the superconducting\ngap, which is also numerically obtained."
    },
    {
        "anchor": "Josephson effect for SU(4) carbon nanotube quantum dots: We present the theory of the Josephson effect in nanotube dots where an SU(4)\nsymmetry can be realized. We find a remarkably rich phase diagram that\nsignificantly differs from the SU(2) case. In particular, \\pi-junction behavior\nis largely suppressed. We analytically obtain the Josephson current in various\nparameter regions: (i) in the Kondo regime, covering the full crossover from\nSU(4) to SU(2), (ii) for weak tunnel couplings, and (iii) for large BCS gap.\nThe transition between these regions is studied numerically.",
        "positive": "Low-energy band structure and even-odd layer number effect in AB-stacked\n  multilayer graphene: How atoms acquire three-dimensional bulk character is one of the fundamental\nquestions in materials science. Before addressing this question, how atomic\nlayers become a bulk crystal might give a hint to the answer. While atomically\nthin films have been studied in a limited range of materials, a recent\ndiscovery showing how to mechanically exfoliate bulk crystals has opened up the\nfield to study the atomic layers of various materials. Here, we show systematic\nvariation in the band structure of high mobility graphene with one to seven\nlayers by measuring the quantum oscillation of magnetoresistance. The Landau\nfan diagram showed distinct structures that reflected differences in the band\nstructure, as if they were finger prints of multilayer graphene. In particular,\nan even-odd layer number effect was clearly observed, with the number of bands\nincreasing by one for every two layers and a Dirac cone observed only for an\nodd number of layers. The electronic structure is significantly influenced by\nthe potential energy arising from carrier screening associated with a gate\nelectric field."
    },
    {
        "anchor": "Localized Joule heating produced by ion current focusing through\n  micron-size holes: We provide an experimental demonstration that the focusing of ionic currents\nin a micron size hole connecting two chambers can produce local temperature\nincreases of up to $100^\\circ$ C with gradients as large as $1^\\circ$ K$\\mu\nm^{-1}$. We find a good agreement between the measured temperature profiles and\na finite elements-based numerical calculation. We show how the thermal\ngradients can be used to measure the full melting profile of DNA duplexes\nwithin a region of 40 $\\mu$m. The possibility to produce even larger gradients\nusing sub-micron pores is discussed.",
        "positive": "Impact of ex-situ rapid thermal annealing on the magneto-optical\n  properties and the oscillator strength of In(Ga)As quantum dots: We discuss the influence of a rapid thermal annealing step on the\nmagneto-optical emission properties of In(Ga)As/GaAs quantum dots. We map out a\nstrong influence of the growth- and anneling parameters on the quantum\nexcitons' effective Land\\'e g-factors and in particular on their diamagnetic\ncoefficients, which we directly correlate with the modification of the emitters\nshape and material composition. In addition, we study the excitons' spontaneous\nemission lifetime as a function of the annealing temperature and the dot\nheight, and observe a strong increase of the emission rate with the quantum dot\nvolume. The corresponding increase in oscillator strenth yields fully\nconsistent results with the analysis of the diamagenic behavior. In particular,\nwe demonstrate that a rapid thermal annealing step of 850$^\\circ$ C can be\nemployed to increase the oscillator strength of as-grown InAs/GaAs QDs by more\nthan a factor of $2$."
    },
    {
        "anchor": "Optical properties of anisotropic Dirac semimetals: The current-dipole conductivity formula for doped three-dimensional Dirac\nsemimetals is derived by using a modified gauge-invariant tight-binding\napproach. In a heavily doped regime, the effective number of charge carriers\n$n_{\\alpha \\alpha}^{\\rm eff}$ in the Drude contribution is found to be by a\nfactor of 4 larger than the nominal electron concentration $n$. However, its\nstructure is the same as in standard Fermi liquid theory. In a lightly doped\nregime, on the other hand, the ratio $n_{\\alpha \\alpha}^{\\rm eff}/n$ is much\nlarger, with much more complex structure of $n_{\\alpha \\alpha}^{\\rm eff}$. It\nis shown that the dc resistivity and reflectivity date measured in two TlBiSSe\nsamples can be easily understood, even in the relaxation-time approximation,\nprovided that finite quasiparticle lifetime effects in the momentum\ndistribution functions are properly taken into account.",
        "positive": "Persistent Optically Induced Magnetism in Oxygen-Deficient Strontium\n  Titanate: Strontium titanate (SrTiO$_3$) is a foundational material in the emerging\nfield of complex oxide electronics. While its electronic and optical properties\nhave been studied for decades, SrTiO$_3$ has recently become a renewed\nmaterials research focus catalyzed in part by the discovery of magnetism and\nsuperconductivity at interfaces between SrTiO$_3$ and other oxides. The\nformation and distribution of oxygen vacancies may play an essential but\nas-yet-incompletely understood role in these effects. Moreover, recent\nsignatures of magnetization in gated SrTiO$_3$ have further galvanized interest\nin the emergent properties of this nominally nonmagnetic material. Here we\nobserve an optically induced and persistent magnetization in oxygen-deficient\nSrTiO$_{3-\\delta}$ using magnetic circular dichroism (MCD) spectroscopy and\nSQUID magnetometry. This zero-field magnetization appears below ~18K, persists\nfor hours below 10K, and is tunable via the polarization and wavelength of\nsub-bandgap (400-500nm) light. These effects occur only in oxygen-deficient\nsamples, revealing the detailed interplay between magnetism, lattice defects,\nand light in an archetypal oxide material."
    },
    {
        "anchor": "Shape Deformation driven Structural Transitions in Quantum Hall\n  Skyrmions: The Quantum Hall ground state away from $\\nu = 1$ can be described by a\ncollection of interacting skyrmions. We show within the context of a nonlinear\nsigma model, that the classical ground state away from $\\nu = 1$ is a skyrmion\ncrystal with a generalized N\\'eel order. We show that as a function of filling\n$\\nu$, the skyrmion crystal undergoes a triangle to square to triangle\ntransition at zero temperature. We argue that this structural transition,\ndriven by a change in the shape of the individual skyrmions, is stable to\nthermal and quantum fluctuations and may be probed experimentally.",
        "positive": "Controllable Optical Negative Refraction and Phase Conjugation in\n  Graphene: The development of optical metamaterials has resulted in the demonstration of\nremarkable physical properties, including cloaking, optical magnetism, and\nnegative refraction. The latter has attracted particular interest, mainly\nbecause of its promise for super-resolution imaging. In recent years, negative\nrefraction has been demonstrated with plasmonic materials and nonlinear\ndiscrete elements. However, the widespread use of negative refraction at\noptical frequencies is limited by high losses and strong dispersion effects,\nwhich typically limits operation to narrow frequency bands. Here we use\ndegenerate four-wave mixing (d-4WM) to demonstrate controllable negative\nrefraction at a graphene interface, which acts as a highly efficient\nphase-conjugating surface. The scheme has very low loss because of the very\nsmall thickness of the nonlinear material and it ensures broadband operation\ndue to the linear bandstructure of graphene."
    },
    {
        "anchor": "Hourglass Dirac Chain Metal in Rhenium Dioxide: Nonsymmorphic symmetries, which involve fractional lattice translations in\ncrystalline materials, can generate exotic types of fermionic excitations that\nare robust against spin-orbit coupling. Here we report on a hourglass-type\ndispersion in the bulk of three-dimensional rhenium dioxide crystals, as\ndictated by its nonsymmorphic symmetries. Due to time reversal and inversion\nsymmetries, each band has an additional two-fold degeneracy, making the neck\ncrossing-point of the hourglass four-fold degenerate. Remarkably, close to the\nFermi level, the neck crossing-point traces out a Dirac chain--a chain of\nconnected four-fold-degenerate Dirac loops--in the momentum space. The symmetry\nprotection, the transformation under symmetry-breaking, and the associated\ntopological surface states of the hourglass Dirac chain are discussed.",
        "positive": "Interacting electrons in a nearly straight quantum wire: The conductance threshold of a clean nearly straight quantum wire in which a\nsingle electron is bound is studied. This exhibits spin-dependent conductance\nanomalies on the rising edge to the first conductance plateau, near\nG=0.25(2e^{2}/h) and G=0.7(2e^{2}/h), related to a singlet and triplet\nresonances respectively. We show that the problem may be mapped on to an\nAnderson-type of Hamiltonian and calculate the energy dependence of the energy\nparameters in the resulting model."
    },
    {
        "anchor": "Photoinduced polarization enhancement in biased bilayer graphene in the\n  Landau level regime: We investigate the charge carrier dynamics in bilayer graphene subject to\nmonochromatic laser irradiation within the Landau level quantization regime.\nEven though the radiation field does not lift the energy degeneracy of the\nlowest Landau levels (LLs), it nevertheless has a strong effect on the\nphotoinduced pseudospin polarization response for higher LLs ($n\\ge2$). Our\nresults show that the photoinduced bandgaps lead to a finite response of the\naveraged pseudospin polarization with nontrivial oscillating behavior. It is\nshown that the contribution from these higher LL transitions turns out to be\ncrucial to achieve an enhanced photoinduced polarization in radiated bilayer\ngraphene. The experimental feasibility of our findings is also discussed.",
        "positive": "Crystal Nucleation Modeling of Solvent Molecules Influence on Radius and\n  Morphology of Nano Copper Ferrite Particles: Nanometer copper ferrite, as a kind of nanometer particle with catalytic\nactivity, and its photothermal and magnetothermal effects as ferrite, can be\nwidely used in different fields. It is a general way to obtain the nano effect\nof the target by controlling the particle size. In this paper, the\ncrystallization process of hydrothermal/solvothermal synthesis was analyzed,\nand the nucleation model was established to simulate the effects of solvent,\nreaction temperature and cooling time on the particle size of copper ferrite\nnanoparticles. Through Monte Carlo method and energy function, the ratio of\nnano particle agglomeration was established, and the influence of different\nreaction conditions on it was discussed."
    },
    {
        "anchor": "Graphene resistivity in diffusive limit due to scalar and vector\n  potential electron-phonon scattering: We calculate the contribution of unscreened and screened scalar and vector\npotential electron acoustic phonon coupling to resistivity in disordered\ngraphene through Keldysh Greens function method within the diffusive limit. We\nobtain analytical results in the asymptotic limits of clean and strong\nimpurities for both DP and VP coupling, which is in observed to be in good\nagreement with the resistivity behavior in these limits. We find that the\ncomplete numerical results approach the analytical result in the extreme\nlimits, but give different temperature dependencies in between these limits.\nThe graphene resistivity has been investigated as functions of temperature,\nmean free path and carrier density. We also evaluated the screened behavior in\nthe Thomas Fermi and Random phase approximation dielectric function and\nobtained the temperature power exponents. We find that in the absence of\nscreening when the electronic disorder is less than the critical disoeder\nlimit, the two coupling mechanisms are affected differently and the relaxation\nrate associated with the VP coupling is suppressed by disorder as compared to\nthe DP coupling, and the DP coupling is enhanced by disorder.",
        "positive": "High Fidelity Single-Shot Singlet-Triplet Readout of Precision Placed\n  Donors in Silicon: In this work we perform direct single-shot readout of the singlet-triplet\nstates in exchange coupled electrons confined to precision placed donor atoms\nin silicon. Our method takes advantage of the large energy splitting given by\nthe Pauli-spin blockaded (2,0) triplet states, from which we can achieve a\nsingle-shot readout fidelity of 98.4$\\pm$0.2%. We measure the triplet-minus\nrelaxation time to be of the order 3s at 2.5T and observe its predicted\ndecrease as a function of magnetic field, reaching 0.5s at 1T."
    },
    {
        "anchor": "Nonlocality of electrically-induced spin accumulation in chiral metals: Spin accumulation induced by an electric field in chiral electron system is\ninvestigated based on a linear response theory. It is shown that the spin\nresponse function has a spatially uniform component due to the chiral angular\nmomentum generation effect, resulting in a nonlocal spin generation. The result\nsuggests a scenario for nonlocal long-range spin transport in chiral metals\nreported experimentally recently.",
        "positive": "Controlled phase gate in exchange coupled quantum dots affected by\n  quasistatic charge noise: Charge noise has been one of the main issues in realizing high fidelity\ntwo-qubit quantum gates in semiconductor based qubits. Here, we study the\ninfluence of quasistatic noise in quantum dot detuning on the controlled phase\ngate for spin qubits that defined on a double quantum dot. Analytical\nexpressions for the noise averaged Hamiltonian, exchange interaction, as well\nas the gate fidelity are derived for weak noise covering experimental relevant\nregime. We also perform interleaved two-qubit randomized benchmarking analysis\nfor the controlled phase gate and show that an exponential decay of the\nsequential fidelity is still valid for the weak noise."
    },
    {
        "anchor": "Current fluctuations of an interacting quantum dot: We calculate the counting statistics of electron transfer through an open\nquantum dot with charging interaction. A dot that is connected to leads by two\nsingle-channel quantum point contacts in an in-plane magnetic field is\ndescribed by a Luttinger liquid with impurity at the Toulouse point. We find\nthat the fluctuations of the current through this conductor exhibit distinctive\ninteraction effects. Fluctuations saturate at high voltages, while the mean\ncurrent increases linearly with the bias voltage. All cumulants higher than the\nsecond one reach at large bias a temperature independent limit.",
        "positive": "Weak localization in monolayer and bilayer graphene: We describe the weak localization correction to conductivity in ultra-thin\ngraphene films, taking into account disorder scattering and the influence of\ntrigonal warping of the Fermi surface. A possible manifestation of the chiral\nnature of electrons in the localization properties is hampered by trigonal\nwarping, resulting in a suppression of the weak anti-localization effect in\nmonolayer graphene and of weak localization in bilayer graphene. Intervalley\nscattering due to atomically sharp scatterers in a realistic graphene sheet or\nby edges in a narrow wire tends to restore weak localization resulting in\nnegative magnetoresistance in both materials."
    },
    {
        "anchor": "Anomalous Bloch oscillation and electrical switching of edge\n  magnetization in bilayer graphene nanoribbon: Graphene features topological edge bands that connect the pair of Dirac\npoints through either sectors of the 1D Brillouin zone depending on edge\nconfigurations (zigzag or bearded). Because of their flat dispersion,\nspontaneous edge magnetisation can arise from Coulomb interaction in graphene\nnanoribbons, which has caught remarkable interest. We find an anomalous Bloch\noscillation in such edge bands, in which the flat dispersion freezes electron\nmotion along the field direction, while the topological connection of the bands\nthrough the bulk leads to electron oscillation in the transverse direction\nbetween edges of different configurations on opposite sides/layers of a bilayer\nribbon. Our Hubbard-model mean-field calculation shows that this phenomenon can\nbe exploited for electrical switching of edge magnetisation configurations.",
        "positive": "Rarita-Schwinger-Weyl semimetal in Jeff=3/2 electron systems: We propose a relativistic Jeff=3/2 semimetal with 4d1 or 5d1 electrons on a\ncubic lattice when the strong spin-orbital coupling takes over the Hunds'\ncoupling. A relativistic spinor with spin 3/2 is historically called\nRarita-Schwinger spinor. In the massless case, the right- and left-handed\nchiral degrees of freedom of the Rarita-Schwinger spinors are independent. In\nthe lattice model that we propose, the right- and left- handed gapless points\nin Brillouin zone are separated. We call this linearly dispersed semimetal\nRarita-Schwinger-Weyl semimetal, similar to Weyl semimetal for spin 1/2\nsystems. There is a network of gapless Fermi arcs in the surface Brillouin zone\nif n1+n2+n3 is even for the normal vector (n1,n2,n3) of the surface while the\nsurface is insulator if n1+n2+n3 is odd."
    },
    {
        "anchor": "Quantized thermal and spin transports of dirty planar topological\n  superconductors: Nontrivial bulk topological invariants of quantum materials can leave their\nsignatures on charge, thermal and spin transports. In two dimensions, their\nimprints can be experimentally measured from well-developed multi-terminal Hall\nbar arrangements. Here, we numerically compute the low temperature ($T$)\nthermal ($\\kappa_{xy}$) and zero temperature spin ($\\sigma^{sp}_{xy}$) Hall\nconductivities, and longitudinal thermal conductance ($G^{th}_{xx}$) of various\nparadigmatic two-dimensional fully gapped topological superconductors,\nbelonging to distinct Altland-Zirnbauer symmetry classes, namely $p+ip$ (class\nD), $d+id$ (class C) and $p \\pm ip$ (class DIII) paired states, in mesoscopic\nsix-terminal Hall bar setups from the scattering matrix formalism using Kwant.\nIn both clean and weak disorder limits, the time-reversal symmetry breaking\n$p+ip$ and $d+id$ pairings show half-quantized and quantized $\\kappa_{xy}$ [in\nunits of $\\kappa_0=\\pi^2 k^2_B T/(3h)$], respectively, while the latter one in\naddition accommodates a quantized $\\sigma^{sp}_{xy}$ [in units of\n$\\sigma^{sp}_0=\\hbar/(8 \\pi)$]. By contrast, the time-reversal invariant $p \\pm\nip$ pairing only displays a quantized $G^{th}_{xx}$ at low $T$ up to a moderate\nstrength of disorder. In the strong disorder regime, all these topological\nresponses ($\\kappa_{xy}$, $\\sigma^{sp}_{xy}$ and $G^{th}_{xx}$) vanish.\nPossible material platforms hosting such paired states and manifesting these\nrobust topological thermal and spin responses are highlighted.",
        "positive": "First-principles study of bandgap effects in graphene due to hydrogen\n  adsorption: Hydrogen adsorption on graphene in commensurate periodic arrangements leads\nto bandgap opening at the Dirac point and the emergence of dispersionless\nmidgap bands. We study these bandgap effects and their dependence on\nperiodicity for a single hydrogen adsorbate on periodic graphene supercells\nusing spin-polarized density-functional theory calculations. Our results show\nthat for certain periodicities, marked by a scale factor of three, the bandgap\nis suppressed to a great extent, and has a special level structure around the\nneutrality point. We present explanations for the origin of the changes to the\nband structure in terms of the \\textit{ab initio} Hamiltonian matrix. This\nmethod may be used to obtain a more accurate tight-binding description of\nsingle hydrogen adsorption on graphene."
    },
    {
        "anchor": "Topological insulators are tunable waveguides for hyperbolic polaritons: Layered topological insulators, for example, Bi$_2$Se$_3$ are optically\nhyperbolic materials in a range of THz frequencies. Such materials possess\ndeeply subdiffractional, highly directional collective modes: hyperbolic\nphonon-polaritons. In thin crystals the dispersion of such modes is split into\ndiscrete subbands and is strongly influenced by electron surface states. If the\nsurface states are doped, then hybrid collective modes result from coupling of\nthe phonon-polaritons with surface plasmons. The strength of the hybridization\ncan be controlled by an external gate that varies the chemical potential of the\nsurface states. Momentum-dependence of the plasmon-phonon coupling leads to a\npolaritonic analog of the Goos-H\\\"anchen effect. Directionality of the\npolaritonic rays and their tunable Goos-H\\\"anchen shift are observable via THz\nnanoimaging.",
        "positive": "Proximity effect in ferromagnet-superconductor hybrid structures: role\n  of the pairing symmetry: The spatial variations of the pair amplitude, and the local density of states\nin d-wave or s-wave superconductor-ferromagnet hybrid structures are calculated\nself consistently using the Bogoliubov-deGennes formalism within the two\ndimensional extended Hubbard model. We describe the proximity effect in\nsuperconductor / ferromagnet (SF) bilayers, FSF trilayers, and interfaces\nbetween a superconductor and a ferromagnetic domain wall. We investigate in\ndetail the role played by the pairing symmetry, the exchange field, interfacial\nscattering and crossed Andreev reflection."
    },
    {
        "anchor": "Density density correlation functions of chiral Luttinger liquids with a\n  point contact impurity: The density density correlation function (most singular parts) of chiral\nLuttinger liquids forming the fractional quantum Hall effect (FQHE) edge is\nsystematically derived in presence of a point-contact junction acting as a\nlocalised scalar impurity and is shown to be expressible as compact analytical\nfunctions with second order poles and involving the bare scale-independent\nreflection and transmission coefficients. The results are validated on\ncomparison with standard fermionic perturbation theory. The linear response\nHall conductance in the absence of a point-contact is recovered from the\nobtained density density correlation functions (DDCF). The system under\nconsideration is inhomogeneous with broken translational invariance and for\nsuch systems in one dimension, the connected moments of the density fluctuation\noperator beyond second order need not be included in order to retreive the most\nsingular parts of the correlations. The reason being that all odd moments of\nthe density are zero and all higher order even moments are less singular than\nthe quadratic moment. The implications of these results when used in\nconjunction with bosonization methods in presence of impurity backscattering is\nbriefly discussed.",
        "positive": "Quantitative $\u03bc$PIV Measurements of Velocity Profiles: In Microscopic Particle Image Velocimetry ($\\mu$PIV), velocity fields in\nmicrochannels are sampled over finite volumes within which the velocity fields\nthemselves may vary significantly. In the past, this has limited measurements\noften to be only qualitative in nature, blind to velocity magnitudes. In the\npursuit of quantitatively useful results, one has treated the effects of the\nfinite volume as errors that must be corrected by means of ever more\ncomplicated processing techniques. Resulting measurements have limited\nrobustness and require convoluted efforts to understand measurement\nuncertainties. To increase the simplicity and utility of $\\mu$PIV measurements,\nwe introduce a straightforward method, based directly on measurement, by which\none can determine the size and shape of the volume over which moving fluids are\nsampled. By comparing measurements with simulation, we verify that this method\nenables quantitative measurement of velocity profiles across entire channels,\nas well as an understanding of experimental uncertainties. We show how the\nmethod permits measurement of an unknown flow rate through a channel of known\ngeometry. We demonstrate the method to be robust against common sources of\nexperimental uncertainty. We also apply the theory to model the technique of\nScanning $\\mu$PIV, which is often used to locate the center of a channel, and\nwe show how and why it can in fact misidentify the center. The results have\ngeneral implications for research and development that requires reliable,\nquantitative measurement of fluid flow on the micrometer scale and below."
    },
    {
        "anchor": "Electronic pumping of heat without charge transfer: A mechanism of electron-mediated pumping of heat in the absence of net charge\ntransfer is proposed. It may be realized in charge-neutral electron systems,\nsuch as graphene, coupled to an external electric potential. The flow of heat\nin this pumping cycle is not accompanied by a buildup of voltage along the\nsystem, which offers advantages over traditional thermoelectric cooling setups.\nEfficiency of heat pumping and magnitude of heat flux are studied in the\nhydrodynamic regime for weak disorder. In a pristine system, even for an\ninfinitesimal pumping potential the heat flux remains finite. In particular,\nfor a potential in the form of a traveling wave moving with velocity $c$ the\npumping is perfect; the entire heat content of the electron liquid is advected\nwith velocity $c$. For a general pumping cycle the heat flux is determined by\nthe cycle geometry and disorder strength.",
        "positive": "Suppression of the Kondo Effect in a Quantum Dot by Microwave Radiation: We have studied the influence of microwave radiation on the transport\nproperties of a semiconductor quantum dot in the Kondo regime. In the entire\nfrequency range tested (10--50 GHz), the Kondo resonance vanishes by increasing\nthe microwave power. This suppression of the Kondo resonance shows an\nunexpected scaling behavior. No evidence for photon-sideband formation is\nfound. The comparison with temperature-dependence measurements indicates that\nradiation-induced spin dephasing plays an important role in the suppression of\nthe Kondo effect."
    },
    {
        "anchor": "Extending the spin excitation lifetime of a magnetic molecule on a\n  proximitized superconductor: Magnetic molecules deposited on surfaces are a promising platform to\nindividually address and manipulate spins. Long spin excitation lifetimes are\nnecessary to utilize them in quantum information processing and data storage.\nNormally, coupling of the molecular spin with the conduction electrons of\nmetallic surfaces causes fast relaxation of spin excitations into the ground\nstate. However, the presence of superconducting paring effects in the substrate\ncan protect the excited spin from decaying. In this work, we show that a\nproximity-induced superconducting gold film can sustain spin excitations of a\nFeTPP-Cl molecule for more than 80ns. This long value was determined by\nstudying inelastic spin excitations of the S=5/2 multiplet of FeTPP-Cl on Au\nfilms over V(100) using scanning tunneling spectroscopy. The spin lifetime\ndecreases with increasing film thickness, in apparent connection with the\ngradual gap-closing of a pair of de Gennes-Saint James resonances found inside\nthe superconducting gap. Our results elucidate the use of proximitized gold\nelectrodes for addressing quantum spins on surfaces, envisioning new routes for\ntuning the value of their spin lifetime.",
        "positive": "A new collective mode in the fractional quantum Hall liquid: We apply the methods of continuum mechanics to the study of the collective\nmodes of the fractional quantum Hall liquid. Our main result is that at long\nwavelength there are {\\it two} distinct modes of oscillations, while previous\ntheories predicted only {\\it one}. The two modes are shown to arise from the\ninternal dynamics of shear stresses created by the Coulomb interaction in the\nliquid. Our prediction is supported by recent light scattering experiments,\nwhich report the observation of two long-wavelength modes in a quantum Hall\nliquid."
    },
    {
        "anchor": "Electrically Tunable Fine Structure of Negatively Charged Excitons in\n  Gated Bilayer Graphene Quantum Dots: We predict here the fine structure of an electrically tunable negatively\ncharged exciton (trion) composed of two electrons and a hole confined in a\ngated bilayer graphene quantum dot (QD). We start with an atomistic approach,\nallowing us to compute confined electron and confined hole QD states for a\nstructure containing over one million atoms. Using atomistic wavefunctions we\ncompute Coulomb matrix elements and self-energies. In the next step, by solving\nthe Bethe-Salpeter-like equation for trions, we describe a negatively charged\nexciton, built as a strongly interacting interlayer complex of two electrons in\nthe conduction band and one hole in the valence band. Unlike in conventional\nsemiconducting QDs, we show that the trion contains a fine structure composed\nof ten states arising from the valley and spin degrees of freedom. Finally, we\nobtain absorption into and emission from the trion states. We predict the\nexistence of bright low-energy states and propose to extract the fine structure\nof the trion using the temperature dependence of emission spectra.",
        "positive": "Valley Zeeman Effect in Elementary Optical Excitations of a Monolayer\n  WSe2: A monolayer of a transition metal dichalcogenide (TMD) such as WSe$_2$ is a\ntwo-dimensional (2D) direct band-gap valley-semiconductor having an effective\nHoneycomb lattice structure with broken inversion symmetry. The inequivalent\nvalleys in the Brillouin zone could be selectively addressed using\ncircularly-polarized light fields, suggesting the possibility for\nmagneto-optical measurement and manipulation of the valley pseudospin degree of\nfreedom. Here we report such experiments that demonstrate the valley Zeeman\neffect -- strongly anisotropic lifting of the degeneracy of the valley\npseudospin degree of freedom using an external magnetic field. While the\nvalley-splitting measured using the exciton transition is consistent with the\ndifference of the conduction and valence band orbital magnetic moments, the\ntrion transition exhibits an unexpectedly large valley Zeeman effect which\ncannot be understood using an independent electron-hole picture. Instead, we\nfind an explanation using the recently predicted large Berry curvature and the\nassociated magnetic moment for the electron-hole exchange interaction modified\ntrion dispersion. Our results raise the possibility of observing optical\nexcitation induced valley Hall effect in monolayer TMDs or topological states\nof photons strongly coupled to trion excitations in a microcavity."
    },
    {
        "anchor": "One-particle density matrix and momentum distribution function of\n  one-dimensional anyon gases: We present a systematic study of the Green functions of a one-dimensional gas\nof impenetrable anyons. We show that the one-particle density matrix is the\ndeterminant of a Toeplitz matrix whose large N asymptotic is given by the\nFisher-Hartwig conjecture. We provide a careful numerical analysis of this\ndeterminant for general values of the anyonic parameter, showing in full\ndetails the crossover between bosons and fermions and the reorganization of the\nsingularities of the momentum distribution function.\n  We show that the one-particle density matrix satisfies a Painleve VI\ndifferential equation, that is then used to derive the small distance and large\nmomentum expansions. We find that the first non-vanishing term in this\nexpansion is always k^{-4}, that is proved to be true for all couplings in the\nLieb-Liniger anyonic gas and that can be traced back to the presence of a delta\nfunction interaction in the Hamiltonian.",
        "positive": "Probing topological quantum matter with scanning tunnelling microscopy: The search for topological phases of matter is evolving towards strongly\ninteracting systems, including magnets and superconductors, where exotic\neffects emerge from the quantum-level interplay between geometry, correlation\nand topology. Over the past decade or so, scanning tunnelling microscopy has\nbecome a powerful tool to probe and discover emergent topological matter,\nbecause of its unprecedented spatial resolution, high-precision electronic\ndetection and magnetic tunability. Scanning tunnelling microscopy can be used\nto probe various topological phenomena, as well as complement results from\nother techniques. We discuss some of these proof-of-principle methodologies\napplied to probe topology, with particular attention to studies performed under\na tunable vector magnetic field, which is a relatively new direction of recent\nfocus. We then project the future possibilities for atomic-resolution\ntunnelling methods in providing new insights into topological matter."
    },
    {
        "anchor": "Time-dependent simulation of particle and displacement currents in THz\n  graphene transistors: Although time-independent models provide very useful dynamical information\nwith a reduced computational burden, going beyond the quasi-static\napproximation provides enriched information when dealing with TeraHertz (THz)\nfrequencies. In this work, the THz noise of dual-gate graphene transistors with\nDC polarization is analyzed from a careful simulation of the time-dependent\nparticle and displacement currents. From such currents, the power spectral\ndensity (PSD) of the total current fluctuations are computed at the source,\ndrain and gate contacts. The role of the lateral dimensions of the transistors,\nthe Klein tunneling and the positive-negative energy injection on the PSD are\nanalyzed carefully. Through the comparison of the PSD with and without\nBand-to-Band tunneling and graphene injection, it is shown that the unavoidable\nKlein tunneling and positive-negative energy injection in graphene structures\nimply an increment of noise without similar increment on the current, degrading\nthe (either low or high frequency) signal-to-noise ratio. Finally, it is shown\nthat the shorter the vertical height (in comparison with the length of the\nactive region in the transport direction), the larger the maximum frequency of\nthe PSD. As a byproduct of this result, an alternative strategy (without length\nscaling) to optimize the intrinsic cut-off frequency of graphene transistors is\nenvisioned.",
        "positive": "Designing adiabatic time-evolution from high frequency bichromatic\n  sources: We investigate the quantum dynamics of a two-level system driven by a\nbichromatic field, using a non-perturbative analysis. We make special emphasis\nin the case of two large frequencies, where the Magnus expansion can fail, and\nin the case of a large and a small frequency, where resonances can dominate. In\nthe first case, we show that two large frequencies can be combined to produce\nan effective adiabatic evolution. In the second case, we show that high\nfrequency terms (which naturally arise as corrections to the adiabatic\nevolution obtained in the first case) can be used to produce a highly tunable\nadiabatic evolution over the whole Bloch sphere, controlled by multi-photon\nresonances."
    },
    {
        "anchor": "Hall potentiometer in the ballistic regime: We demonstrate theoretically how a two-dimensional electron gas can be used\nto probe local potential profiles using the Hall effect. For small magnetic\nfields, the Hall resistance is inversely proportional to the average potential\nprofile in the Hall cross and is independent of the shape and the position of\nthis profile in the junction. The bend resistance, on the other hand, is much\nmore sensitive on the exact details of the local potential profile in the cross\njunction.",
        "positive": "Fully spin-polarized quadratic non-Dirac bands realized quantum\n  anomalous Hall effect: The quantum anomalous Hall effect is a intriguing quantum state which\nexhibits the chiral edge states in the absence of magnetic field. While the\nsearch for quantum anomalous Hall insulators is still active, the researchers\nmainly search for the systems containing magnetic atom. Here, based on\nfirst-principles density functional theory, we predict a new family of chern\ninsulators with fully spin-polarized quadratic px;y non-Dirac bands in the\nalkali earth metal BaX (X = Si, Ge, Sn) system. We show that BaX monolayer has\na half-metallic ferromagnetic ground state. The ferromagnetism is mainly\noriginated from the p orbitals of Si, Ge and Sn atoms. The 2D BaSn monolayer\nexhibits a large magnetocrystalline anisotropic energy of 12.20 meV/cell and a\nnontrivial band gap of 159.10 meV. Interestingly, both the spin polarization of\nthe chiral edge currents and the sign of Chern number can be tuned by doping.\nFurthermore, the 4 % compressive strain can drive structural phase transition\nbut the nontrivial topological properties remain reserve in the 2D BaX systems.\nOur findings not only extend the novel concepts but also provide fascinating\nopportunities for the realization of quantum anomalous Hall effect\nexperimentally."
    },
    {
        "anchor": "Semiclassical conservation of spin and large transverse spin current in\n  Dirac systems: In Dirac materials, the low energy excitations obey the relativistic Dirac\nequation. This dependence implies that the electrons are exposed to strong\nspin-orbit coupling. Hence, real spin conservation is believed to be violated\nin Dirac materials. We show that this point of view needs to be refined in the\nsemiclassical picture which applies to the case of doped Dirac materials (away\nfrom the nodal point in the spectrum). We derive a novel type of Boltzmann\nequation for these systems if they are brought slightly out-of-equilibrium.\nRemarkably, spin-momentum locking is softened and a generalized spin\nconservation law can be formulated. The most striking observable consequence of\nour theory is a large transverse spin current in a nearly ballistic transport\nregime.",
        "positive": "Multi-walled carbon nanotube films for the measurement of the alcoholic\n  concentration: We show that a multi-walled carbon nanotube film can be used as the sensing\nelement of a low-cost sensor for the alcoholic concentration in liquid\nsolutions. To this purpose, we investigate the electrical resistance of the\nfilm as a function of the isopropanol concentration in a water solution. The\nanalysis reveals a growing resistance with increasing isopropanol concentration\nand a fast response. The sensing element is re-usable as the initial resistance\nvalue is restored once the solution has evaporated. The electrical resistance\nincreases linearly when the multi-walled carbon nanotube film is exposed to\ncommon beverages with increasing alcoholic content. This work paves the way for\nthe development of low-cost, miniaturized MWCNT-based sensors for quality\nmonitoring and control of alcoholic beverages and general liquid solutions."
    },
    {
        "anchor": "Strongly correlated charge transport in silicon MOSFET quantum dots: Quantum shot noise probes the dynamics of charge transfers through a quantum\nconductor, reflecting whether quasiparticles flow across the conductor in a\nsteady stream, or in syncopated bursts. We have performed high-sensitivity shot\nnoise measurements in a quantum dot obtained in a silicon\nmetal-oxide-semiconductor field-effect transistor. The quality of our device\nallows us to precisely associate the different transport regimes and their\nstatistics with the internal state of the quantum dot. In particular, we report\non large current fluctuations in the inelastic cotunneling regime,\ncorresponding to different highly-correlated, non-Markovian charge transfer\nprocesses. We have also observed unusually large current fluctuations at low\nenergy in the elastic cotunneling regime, the origin of which remains to be\nfully investigated.",
        "positive": "Resonance at the Rabi frequency in a superconducting flux qubit: We analyze a system composed of a superconducting flux qubit coupled to a\ntransmission-line resonator driven by two signals with frequencies close to the\nresonator's harmonics. The first strong signal is used for exciting the system\nto a high energetic state while a second weak signal is applied for probing\neffective eigenstates of the system. In the framework of doubly dressed states\nwe showed the possibility of amplification and attenuation of the probe signal\nby direct transitions at the Rabi frequency. We present a brief review of\ntheoretical and experimental works where a direct resonance at Rabi frequency\nhave been investigated in superconducting flux qubits. The interaction of the\nqubit with photons of two harmonics has prospects to be used as a quantum\namplifier (microwave laser) or an attenuator."
    },
    {
        "anchor": "Deterministic preparation of Dicke states of donor nuclear spins in\n  silicon by cooperative pumping: For donor nuclear spins in silicon, we show how to deterministically prepare\nvarious symmetric and asymmetric Dicke states which span a complete basis of\nthe many-body Hilbert space. The state preparation is realized by cooperative\npumping of nuclear spins by coupled donor electrons, and the required controls\nare in situ to the prototype Kane proposal for quantum computation. This scheme\nonly requires a sub-gigahertz donor exchange coupling which can be readily\nachieved without atomically precise donor placement, hence it offers a\npractical way to prepare multipartite entanglement of spins in silicon with\ncurrent technology. All desired Dicke states appear as the steady state under\nvarious pumping scenarios and therefore the preparation is robust and does not\nrequire accurate temporal controls. Numerical simulations with realistic\nparameters show that Dicke states of 10-20 qubits can be prepared with high\nfidelity in presence of decoherence and unwanted dynamics.",
        "positive": "High Landau levels of 2D electrons near the topological transition\n  caused by interplay of spin-orbit and Zeeman energy shifts: In the presence of spin-orbit coupling two branches of the energy spectrum of\n2D electrons get shifted in the momentum space. Application of in-plane\nmagnetic field causes the splitting of the branches in energy. When both,\nspin-orbit coupling and Zeeman splitting are present, the branches of energy\nspectrum cross at certain energy. Near this energy, the Landau quantization\nbecomes peculiar since semiclassical trajectories, corresponding to individual\nbranches, get coupled. We study this coupling as a function of proximity to the\ntopological transition. Remarkably, the dependence on the proximity is strongly\nasymmetric reflecting the specifics of the behavior of the trajectories near\nthe crossing. Equally remarkable, on one side of the transition, the magnitude\nof coupling is an oscillating function of this proximity. These oscillations\ncan be interpreted in terms of the St{\\\"u}ckelberg interference. Scaling of\ncharacteristic detuning with magnetic length is also unusual. This unusual\nbehavior cannot be captured by simply linearizing the Fermi contours near the\ncrossing point."
    },
    {
        "anchor": "Tuning arrays with rays: Physics-informed tuning of quantum dot charge\n  states: Quantum computers based on gate-defined quantum dots (QDs) are expected to\nscale. However, as the number of qubits increases, the burden of manually\ncalibrating these systems becomes unreasonable and autonomous tuning must be\nused. There has been a range of recent demonstrations of automated tuning of\nvarious QD parameters such as coarse gate ranges, global state topology (e.g.\nsingle QD, double QD), charge, and tunnel coupling with a variety of methods.\nHere, we demonstrate an intuitive, reliable, and data-efficient set of tools\nfor an automated global state and charge tuning in a framework deemed\nphysics-informed tuning (PIT). The first module of PIT is an action-based\nalgorithm that combines a machine learning classifier with physics knowledge to\nnavigate to a target global state. The second module uses a series of\none-dimensional measurements to tune to a target charge state by first emptying\nthe QDs of charge, followed by calibrating capacitive couplings and navigating\nto the target charge state. The success rate for the action-based tuning\nconsistently surpasses 95 % on both simulated and experimental data suitable\nfor off-line testing. The success rate for charge setting is comparable when\ntesting with simulated data, at 95.5(5.4) %, and only slightly worse for\noff-line experimental tests, with an average of 89.7(17.4) % (median 97.5 %).\nIt is noteworthy that the high performance is demonstrated both on data from\nsamples fabricated in an academic cleanroom as well as on an industrial 300 mm}\nprocess line, further underlining the device agnosticism of PIT. Together,\nthese tests on a range of simulated and experimental devices demonstrate the\neffectiveness and robustness of PIT.",
        "positive": "Photon assisted braiding of Majorana fermions in a cavity: We study the dynamical process of braiding Majorana bound states in the\npresence of the coupling to photons in a microwave cavity. We show\ntheoretically that the $\\pi/4$ phase associated with the braiding of Majoranas,\nas well as the parity of the ground state are imprinted into the photonic field\nof the cavity, which can be detected by dispersive readouts techniques. These\nmanifestations are purely dynamical, they occur in the absence of any splitting\nof the MBS that are exchanged, and they disappear in the static setups studied\npreviously. Conversely, the cavity can affect the braiding phase, which in turn\nshould allow for cavity controlled braiding."
    },
    {
        "anchor": "Delocalization and scaling properties of low-dimensional quasiperiodic\n  systems: In this paper, we explore the localization transition and the scaling\nproperties of both quasi-one-dimensional and two-dimensional quasiperiodic\nsystems, which are constituted from coupling several Aubry-Andr\\'{e} (AA)\nchains along the transverse direction, in the presence of next-nearest-neighbor\n(NNN) hopping. The localization length, two-terminal conductance, and\nparticipation ratio are calculated within the tight-binding Hamiltonian. Our\nresults reveal that a metal-insulator transition could be driven in these\nsystems not only by changing the NNN hopping integral but also by the\ndimensionality effects. These results are general and hold by coupling distinct\nAA chains with various model parameters. Furthermore, we show from finite-size\nscaling that the transport properties of the two-dimensional quasiperiodic\nsystem can be described by a single parameter and the scaling function can\nreach the value 1, contrary to the scaling theory of localization of disordered\nsystems. The underlying physical mechanism is discussed.",
        "positive": "The methods to detect vacuum polarization by evanescent modes: We propose the evanescent-mode-sensing methods to probe the electrodynamics\n(QED) vacuum polarization. From our methods, high-sensitivity can be achieved\neven though the external field is much smaller than the Schwinger critical\nfield and may be realizable in contemporary experimental conditions. The\nmethods are based on the effect of phase change and time delay of evanescent\nwave which is transmitted in QED vacuum. These methods can also be widely used\nin sensitive probing of tiny dissipation in other fields."
    },
    {
        "anchor": "Detection of mechanical resonance of a single-electron transistor by\n  direct current: We have suspended an Al based single-electron transistor whose island can\nresonate freely between the source and drain leads forming the clamps. In\naddition to the regular side gate, a bottom gate with a larger capacitance to\nthe SET island is placed underneath to increase the SET coupling to mechanical\nmotion. The device can be considered as a doubly clamped Al beam that can\ntransduce mechanical vibrations into variations of the SET current. Our\nsimulations based on the orthodox model, with the SET parameters estimated from\nthe experiment, reproduce the observed transport characteristics in detail.",
        "positive": "Dissipation due to two-level systems in nano-mechanical devices: We analyze the dissipation of the frequency vibrations of nano-mechanical\ndevices. We show that the coupling between flexural modes and two-level systems\nleads to sub-ohmic dissipation. The inverse quality factor of the low energy\nvibrations depends on temperature as $Q^{-1} (T) \\approx Q_0 + C T^{1/3}$,\nproviding a quantitative description of the experimental data."
    },
    {
        "anchor": "Electronic states in heterostructures formed by ultranarrow layers: Low-energy electronic states in heterosrtuctures formed by ultranarrow layer\n(single or several monolayers thickness) are studied theoretically. The host\nmaterial is described within the effective mass approximation and effect of\nultranarrow layers is taken into account within the framework of the transfer\nmatrix approach. Using the current conservation requirement and the inversion\nsymmetry of ultranarrow layer, the transfer matrix is written through two\nphenomenological parameters. The binding energy of localized state, the\nreflection (transmission) coefficient for the single ultranarrow layer case,\nand the energy spectrum of superlattice are determined by these parameters.\nSpectral dependency of absorption in superlattice due to photoexcitation of\nelectrons from localized states into minibands is strongly dependent on the\nultranarrow layers characteristics. Such a dependency can be used for\nverification of the transfer matrix parameters.",
        "positive": "Quench dynamics in superconducting nanojunctions: metastability and\n  dynamical Yang-Lee zeros: We study the charge transfer dynamics following the formation of a phase or\nvoltage biased su- perconducting nano-junction using a full counting statistics\nanalysis. We demonstrate that the evolution of the zeros of the generating\nfunction allows one to identify the population of different many body states\nmuch in the same way as the accumulation of Yang-Lee zeros of the partition\nfunction in equilibrium statistical mechanics is connected to phase\ntransitions. We give an exact expression connecting the dynamical zeros to the\ncharge transfer cumulants and discuss when an approximation based on \"dominant\"\nzeros is valid. We show that, for generic values of the parameters, the system\ngets trapped into a metastable state characterized by a non-equilibrium\npopulation of the many body states which is dependent on the initial\nconditions. We study in particular the effect of the switching rates in the\ndynamics showing that, in contrast to intuition, the deviation from thermal\nequilibrium increases for the slower rates. In the voltage biased case the\nsteady state is reached independently of the initial conditions. Our method\nallows us to obtain accurate results for the steady state current and noise in\nquantitative agreement with steady state methods developed to describe the\nmultiple Andreev reflections regime. Finally, we discuss the system dynamics\nafter a sudden voltage drop showing the possibility of tuning the many body\nstates population by an appropriate choice of the initial voltage, providing a\nfeasible experimental way to access the quench dynamics and control the state\nof the system."
    },
    {
        "anchor": "Band Structure and Optical Transitions in Atomic Layers of Hexagonal\n  Gallium Chalcogenides: We report density-functional-theory calculations of the electronic band\nstructures and optical absorption spectra of two-dimensional crystals of\nGa$_2$X$_2$ (X=S, Se, and Te). Our calculations show that all three\ntwo-dimensional materials are dynamically stable indirect-band-gap\nsemiconductors with a Mexican-hat dispersion of holes near the top of the\nvalence band. We predict the existence of Lifshitz transitions---changes in the\nFermi-surface topology of hole-doped Ga$_2$X$_2$---at hole concentrations\n$n_{S}=7.96\\times 10^{13}$ cm$^{-2}$, $n_{Se}=6.13\\times 10^{13}$ cm$^{-2}$,\nand $n_{Te}=3.54\\times 10^{13}$ cm$^{-2}$.",
        "positive": "Proposal for a nanoscale variable resistor/electromechanical transistor: A nanoscale variable resistor consisting of a metal nanowire (active\nelement), a dielectric, and a gate, is proposed. By means of the gate voltage,\nstochastic transitions between different conducting states of the nanowire can\nbe induced, with a switching time as fast as picoseconds. With an appropriate\nchoice of dielectric, the transconductance of the device, which may also be\nconsidered an ``electromechanical transistor,'' is shown to significantly\nexceed the conductance quantum G_0=2e^2/h, a remarkable figure of merit for a\nnanoscale device."
    },
    {
        "anchor": "Shot noise of a quantum dot measured with GHz stub impedance matching: The demand for a fast high-frequency read-out of high impedance devices, such\nas quantum dots, necessitates impedance matching. Here we use a resonant\nimpedance matching circuit (a stub tuner) realized by on-chip superconducting\ntransmission lines to measure the electronic shot noise of a carbon nanotube\nquantum dot at a frequency close to 3 GHz in an efficient way. As compared to\nwide-band detection without impedance matching, the signal to noise ratio can\nbe enhanced by as much as a factor of 800 for a device with an impedance of 100\nk$\\Omega$. The advantage of the stub resonator concept is the ease with which\nthe response of the circuit can be predicted, designed and fabricated. We\nfurther demonstrate that all relevant matching circuit parameters can reliably\nbe deduced from power reflectance measurements and then used to predict the\npower transmission function from the device through the circuit. The shot noise\nof the carbon nanotube quantum dot in the Coulomb blockade regime shows an\noscillating suppression below the Schottky value of $2eI$, as well an\nenhancement in specific regions.",
        "positive": "Double Dressing and Manipulation of the Photonic Density of States in\n  Nanostructured Qubits: In this work, a model to study the coupling between a semiconductor qubit and\ntwo timedependent electric fields is developed. By using it in the resonantly\nmonochromatic double dressing regime, control of the local density of optical\nstates is theoretically and numerically demonstrated for a strongly confined\nexciton. Drastic changes in the allowed energy transitions yielding tunable\nbroadening of the optically active frequency ranges, are observed in the\nsimulated emission spectra. The presented results are in excellent qualitative\nand quantitative agreement with recent experimental observations."
    },
    {
        "anchor": "Irradiated three-dimensional Luttinger semimetal: A factory for\n  engineering Weyl semimetals: We study the interaction between elliptically polarized light and a\nthree-dimensional Luttinger semimetal with quadratic band touching using\nFloquet theory. In the absence of light, the touching bands can have the same\nor the opposite signs of the curvature; in each case, we show that simply\ntuning the light parameters allows us to create a zoo of Weyl semimetallic\nphases. In particular, we find that double and single Weyl points can coexist\nat different energies, and they can be tuned to be type I or type II. We also\nfind an unusual phase transition, in which a pair of Weyl nodes form at finite\nmomentum and disappear off to infinity. Considering the broad tunability of\nlight and abundance of materials described by the Luttinger Hamiltonian, such\nas certain pyrochlore iridates, half-Heuslers and zinc-blende semiconductors,\nwe believe this work can lay the foundation for creating Weyl semimetals in the\nlab and dynamically tuning between them.",
        "positive": "Real-time detection of single electron tunneling using a quantum point\n  contact: We observe individual tunnel events of a single electron between a quantum\ndot and a reservoir, using a nearby quantum point contact (QPC) as a charge\nmeter. The QPC is capacitively coupled to the dot, and the QPC conductance\nchanges by about 1% if the number of electrons on the dot changes by one. The\nQPC is voltage biased and the current is monitored with an IV-convertor at room\ntemperature. We can resolve tunnel events separated by only 8 $\\mu$s, limited\nby noise from the IV-convertor. Shot noise in the QPC sets a 25 ns lower bound\non the accessible timescales."
    },
    {
        "anchor": "Aharonov Bohm Effect in Graphene Fabry P\u00e9rot Quantum Hall\n  Interferometers: Quantum interferometers are powerful tools for probing the wave-nature and\nexchange statistics of indistinguishable particles. Of particular interest are\ninterferometers formed by the chiral, one-dimensional (1D) edge channels of the\nquantum Hall effect (QHE) that guide electrons without dissipation. Using\nquantum point contacts (QPCs) as beamsplitters, these 1D channels can be split\nand recombined, enabling interference of charged particles. Such quantum Hall\ninterferometers (QHIs) can be used for studying exchange statistics of anyonic\nquasiparticles. In this study we develop a robust QHI fabrication technique in\nvan der Waals (vdW) materials and realize a graphene-based Fabry-P\\'erot (FP)\nQHI. By careful heterostructure design, we are able to measure pure\nAharonov-Bohm (AB) interference effect in the integer QHE, a major technical\nchallenge in finite size FP interferometers. We find that integer edge modes\nexhibit high visibility interference due to relatively large velocities and\nlong phase coherence lengths. Our QHI with tunable QPCs presents a versatile\nplatform for interferometer studies in vdW materials and enables future\nexperiments in the fractional QHE.",
        "positive": "On the thermal broadening of a quantum critical phase transition: The temperature dependence of an integer Quantum Hall effect transition is\nstudied in a sample where the disorder is dominated by short-ranged potential\nscattering. At low temperatures the results are consistent with a\n$(T/T_0)^{\\kappa}$ scaling behaviour and at higher temperatures by a linear\ndependence similar to that reported in other material systems. It is shown that\nthe linear behaviour results from thermal broadening produced by the\nFermi-Dirac distribution function and that the temperature dependence over the\nwhole range depends only on the scaling parameter T$_0^{\\kappa}$."
    },
    {
        "anchor": "Topologically Protected Transport in Engineered Mechanical Systems: Mechanical vibrations are being harnessed for a variety of purposes and at\nmany length scales, from the macroscopic world down to the nanoscale. The\nconsiderable design freedom in mechanical structures allows to engineer new\nfunctionalities. In recent years, this has been exploited to generate setups\nthat offer topologically protected transport of vibrational waves, both in the\nsolid state and in fluids. Borrowing concepts from electronic physics and being\ncross-fertilized by concurrent studies for cold atoms and electromagnetic\nwaves, this field of topological transport in engineered mechanical systems\noffers a rich variety of phenomena and platforms. In this review, we provide a\nunifying overview of the various ideas employed in this area, summarize the\ndifferent approaches and experimental implementations, and comment on the\nchallenges as well as the prospects.",
        "positive": "Fractal nanostructures with the Hilbert curve geometry as a SERS\n  substrate: We suggest a new type of substrates for the Surface Enhanced Raman Scattering\nmeasurements with the geometry based on self-similar fractal space filling\ncurves. As an example, we have studied theoretically the dielectric response\nproperties of doped semiconductor nanostructures, where the conducting\nelectrons are trapped in the effective potential having the geometry of the\nHilbert curve. We have found that the system may exhibit the induced charge\ndistribution specific for either two dimensional or one dimensional systems,\ndepending on the frequency of the external applied field. We have demonstrated\nthat with the increasing of the depth of the trapping potential the resonance\nof the system counterintuitively shifts to lower frequencies."
    },
    {
        "anchor": "Coherent transfer of spin angular momentum by evanescent spin waves\n  within antiferromagnetic NiO: Insulating antiferromagnets are efficient and robust conductors of spin\ncurrent. To realise the full potential of these materials within spintronics,\nthe outstanding challenges are to demonstrate scalability down to nanometric\nlengthscales and the transmission of coherent spin currents. Here, we report\nthe coherent transfer of spin angular momentum by excitation of evanescent spin\nwaves of GHz frequency within antiferromagnetic NiO at room temperature. Using\nelement-specific and phase-resolved x-ray ferromagnetic resonance, we probe the\ninjection and transmission of ac spin current, and demonstrate that insertion\nof a few nanometre thick epitaxial NiO(001) layer between a ferromagnet and\nnon-magnet can even enhance the flow of spin current. Our results pave the way\ntowards coherent control of the phase and amplitude of spin currents at the\nnanoscale, and enable the realization of spin-logic devices and spin current\namplifiers that operate at GHz and THz frequencies.",
        "positive": "Signal Processing and Control in Nonlinear Nanomechanical Systems: Bestriding the realms of classical and quantum mechanics, nanomechanical\nstructures offer great promise for a huge variety of applications, from\ncomputer memory elements \\cite{badzey04} and ultra-fast sensors to quantum\ncomputing. Intriguing as these possibilities are, there still remain many\nimportant hurdles to overcome before nanomechanical structures approach\nanything close to their full potential. With their high surface-to-volume\nratios and sub-micron dimensions, nanomechanical structures are strongly\naffected by processing irregularities and susceptible to nonlinear effects.\nThere are several ways of dealing with nonlinearity: exceptional fabrication\nprocess control in order to minimize the onset of nonlinear effects or taking\nadvantage of the interesting and oftentimes counterintuitive consequences of\nnonlinearity. Here, we present evidence for the use of stochastic resonance as\na means of coherent signal amplification for use in nanomechanical devices.\nAside from being simply one more system in which the phenomenon has been\ndemonstrated, nanoscale systems \\cite{lee03} are interesting because of their\nproximity to the realm of quantum mechanics. The combination of stochastic\nresonance and quantum mechanics has been the subject of intense theoretical\nactivities \\cite{wellens00, goychuk99, grif96, lof94} for many years;\nnanomechanical systems present a fertile ground for the study of a broad\nvariety of novel phenomena in quantum stochastic resonance. Additionally, the\nphysical realization of such nonlinear nanomechanical strings offer the\npossibility of studying a whole class of phase transition phenomena,\nparticularly those modeled by a Landau-Ginzburg quantum string \\cite{benzi85,\nhu99}."
    },
    {
        "anchor": "Electronic transport in two dimensional Si:P $\u03b4$-doped layers: We investigate theoretically 2D electronic transport in Si:P $\\delta$-doped\nlayers limited by charged-dopant scattering. Since the carrier density is\napproximately equal to the dopant impurity density, the density dependent\ntransport shows qualitatively different behavior from that of the well-studied\n2D Si-MOSFETs where the carrier density is independent of the impurity density.\nWe find that the density dependent mobility of the Si:P system shows\nnon-monotonic behavior which is exactly opposite of the non-monotonicity\nobserved in Si-MOSFETs --- in the Si:P system the mobility first decreases with\nincreasing density and then it increases slowly with increasing density above a\ntypical density $10^{14}$ cm$^{-2}$ (in contrast to Si MOSFETs where the\nmobility typically increases with density first and then slowly decreases at\nhigh density as surface roughness scattering dominates). In the low density\nlimit (or strong screening limit) mobility decreases inversely with increasing\ndensity, but in the high density limit (or weak screening limit) it slowly\nincreases due to the finite width effects of the 2D layer. In the intermediate\ndensity regime ($1/a < 2 k_F < q_{TF}$, where $a$, $k_F$, and $q_{TF}$ are the\nconfinement width of the $\\delta$-layer, Fermi wave vector, and Thomas-Fermi\nscreening wave vector, respectively) the density dependent mobility is\napproximately a constant at the minimum value. However, the calculated mean\nfree path increase monotonically with density. We also compare the transport\nscattering time relevant to the mobility and the single particle relaxation\ntime relevant the quantum level broadening, finding that the transport\nscattering time could be much larger than the single-particle scattering time\nunlike in Si MOSFETs where they are approximately equal.",
        "positive": "Dynamical precession of spin in the two-dimensional spin-orbit coupled\n  systems: We investigate the spin dynamics in the two-dimensional spin-orbit coupled\nsystem subject to an in-plane ($x$-$y$ plane) constant electric field, which is\nassumed to be turned on at the moment $t=0$. The equation of spin precession in\nlinear response to the switch-on of the electric field is derived in terms of\nHeisenberg's equation by the perturbation method up to the first order of the\nelectric field. The dissipative effect, which is responsible for bringing the\ndynamical response to an asymptotic result, is phenomenologically implemented\n\\`{a} la the Landau-Lifshitz-Gilbert equation by introducing damping terms upon\nthe equation of spin dynamics. Mediated by the dissipative effect, the\nresulting spin dynamics asymptotes to a stationary state, where the spin and\nthe momentum-dependent effective magnetic field are aligned again and have\nnonzero components in the out-of-plane ($z$) direction. In the linear response\nregime, the asymptotic response obtained by the dynamical treatment is in full\nagreement with the stationary response as calculated in the Kubo formula, which\nis a time-independent approach treating the applied electric field as\ncompletely time-independent. Our method provides a new perspective on the\nconnection between the dynamical and stationary responses."
    },
    {
        "anchor": "Frequency Modulation and Voltage Locking of the Voltage Controlled Spin\n  Oscillators (VCSOs): The oscillating frequency of typical Spin Torque Nano Oscillators (STNOs) can\nbe modulated by injected DC current or bias magnetic field. And phase locking\nof STNOs to an external Radio Frequency (RF) signal can be imposed by AC\ncurrent or RF bias magnetic field. However, in this study, we have proposed a\nVoltage Controlled Spin Oscillators (VCSOs) by introducing Voltage Controlled\nMagnetic Anisotropy (VCMA) effect. The oscillating frequency of VCSOs can be\nmodulated by VCMA voltage as well as injected DC current. Furthermore, we have\nshown a novel locking mechanism caused by AC VCMA voltage. Both the frequency\nmodulation and voltage locking mechanism are analyzed theoretically by\nNonlinear Auto-oscillator theory and verified by numerical simulation. At last,\nwe proposed that by utilizing negative capacitance material to enhance VCMA\neffect, the locking range for voltage locking can be expanded thus may lead to\neasy mutual synchronization of multiple VCSOs.",
        "positive": "Charge-spin interconversion in graphene-based systems from density\n  functional theory: We present a methodology to address, from first principles, charge-spin\ninterconversion in two-dimensional materials with spin-orbit coupling. Our\nstudy relies on an implementation of density functional theory based quantum\ntransport formalism adapted to such purpose. We show how an analysis of the\n$k$-resolved spin polarization gives the necessary insight to understand the\ndifferent charge-spin interconversion mechanisms. We have tested it in the\nsimplest scenario of isolated graphene in a perpendicular electric field where\neffective tight-binding models are available to compare with. Our results show\nthat the flow of an unpolarized current across a single layer of graphene\nproduces, as expected, a spin separation perpendicular to the current for two\nof the three spin components (out-of-plane and longitudinal), which is the\nsignature of the spin Hall effect. Additionally, it also yields an overall spin\naccumulation for the third spin component (perpendicular to the current), which\nis the signature of the Rashba-Edelstein effect. Even in this simple example,\nour results reveal an unexpected competition between the Rashba and the\nintrinsic spin-orbit coupling. Remarkably, the sign of the accumulated spin\ndensity does not depend on the electron or hole nature of the injected current\nfor realistic values of the Rashba coupling."
    },
    {
        "anchor": "Spectroscopic evidence for electron correlations in the\n  interface-modulated epitaxial bilayer graphene: Superlattice potentials are theoretically predicted to modify the\nsingle-particle electronic structures. The resulting\nCoulomb-interaction-dominated low-energy physics would generate highly novel\nmany-body phenomena. Here, by in situ tunneling spectroscopy, we show the\nsignatures of superstructure-modulated correlated electron states in epitaxial\nbilayer graphene (BLG) on 6H-SiC(0001). As the carrier density is locally\nquasi-'tuned' by the superlattice potentials of a 6x6 interface reconstruction\nphase, the spectral-weight transfer occurs between the two broad peaks flanking\nthe charge-neutral point. Such detected non-rigid band shift beyond the\nsingle-particle band description implies the existence of correlation effects,\nprobably attributed to the modified interlayer coupling in epitaxial BLG by the\n6x6 reconstruction as in magic-angle BLG by the Moire potentials. Quantitative\nanalysis suggests the intrinsic interface reconstruction shows a high carrier\ntunability of around 1/2 filling range, equivalent to the back gating by a\nvoltage of around 70 V in a typical gated BLG/SiO2/Si device. The finding in\ninterface-modulated epitaxial BLG with reconstruction phase extends the BLG\nplatform with electron correlations beyond the magic-angle situation, and may\nstimulate further investigations on correlated states in graphene systems and\nother van der Waals materials.",
        "positive": "All-electrical generation and control of odd-frequency s-wave Cooper\n  pairs in double quantum dots: We propose an all-electrical experimental setup to detect and manipulate the\namplitude of odd-frequency pairing in a double quantum dot. Odd-frequency pair\namplitude is induced from the breakdown of orbital symmetry when Cooper pairs\nare injected in the double dot with electrons in different dots. When the dot\nlevels are aligned with the Fermi energy, i.e., on resonance, nonlocal Andreev\nprocesses are directly connected to the presence of odd-frequency pairing.\nTherefore, their amplitude can be manipulated by tuning the level positions.\nDetection of nonlocal Andreev processes by conductance measurements contributes\na direct proof of the existence of odd-frequency pair amplitude and is\navailable using current experimental techniques."
    },
    {
        "anchor": "Functionalized Graphene in Quantizing Magnetic Field: The case of\n  bunched impurities: Resonant scattering at the atomic absorbates in graphene was investigated\nrecently in relation with the transport and gap opening problems. Attaching an\nimpurity atom to graphene is believed to lead to the creation of unusual zero\nenergy localized electron states. This paper aims to describe the behavior of\nthe localized impurity-induced levels in graphene in a quantizing magnetic\nfield. It is shown that in the magnetic field the impurity level effectively\nhybridizes with one of the n=0 Landau level states and splits into two\nopposite-energy states. The new hybridized state is doubly occupied, forming a\nspin-singlet and reducing the polarization of a Quantum Hall ferromagnet in\nundoped graphene. Taking into account the electron-electron interaction changes\nradically the spectrum of the electrons surrounding the impurity, which should\nbe seen experimentally. While existing publications investigate graphene\nuniformly covered by adatoms, here we address a possibly even more\nexperimentally relevant case of the clusterized impurity distribution. The\nlimit of a dense bunch of the impurity atoms is considered, and it is shown,\nhow such a bunch changes the spectrum and spin polarization of a large dense\nelectron droplet surrounding it. The droplet is encircled by an edge state\ncarrying a persistent current.",
        "positive": "Quantum phase transitions and the degree of nonidentity in the system\n  with two different species of vector bosons: We address the system with two species of vector bosons in an optical\nlattice. In addition to the the standard parameters characterizing such a\nsystem, we are dealing here with the \"degree of atomic nonidentity\",\nmanifesting itself in the difference of tunneling amplitudes and on-site\nCoulomb interactions. We obtain a cascade of quantum phase transitions\noccurring with the increase in the degree of atomic nonidentity. In particular,\nwe show that the phase diagram for strongly distinct atoms is qualitatively\ndifferent from that for (nearly) identical atoms considered earlier. The\nresulting phase diagrams evolve from the images similar to the \"J. Mir\\'o-like\npaintings\" to \"K. Malewicz-like\" ones."
    },
    {
        "anchor": "Tunable Magnetic Skyrmions in Ferrimagnetic Mn$_4$N: Thin films of ferrimagnetic Mn$_4$N are candidate materials to host magnetic\nskyrmions that have demonstrated thermal stability up to 450$^\\circ$C. However,\nthere are no experimental reports observing skyrmions in this system. Here, we\ndiscuss the results of sputter grown 15-17~nm Mn$_4$N thin films on MgO\nsubstrate capped with Pt$_{1-x}$Cu$_{x}$ layers. Vibrating sample magnetometry\nmeasurement of out-of-plane hysteresis loops confirmed that magnetic properties\nare insensitive to the cap layer composition. Imaging based on magnetic force\nmicroscopy measurements observed 300 to 50~nm sized skyrmions, as the Cu\nconcentration was increased from $x$ = 0 to 0.9. We performed density\nfunctional theory calculations and found that the interfacial\nDzyaloshinskii-Moriya interactions (iDMI) follow a trend: Mn$_4$N/MgO(001) $<$\nCu/Mn$_4$N(001) $<$ Pt/Mn$_4$N(001). We infer from these calculations that $x$\nin Pt$_{1-x}$Cu$_{x}$ capping layer can serve as a robust tuning knob to tailor\nthe iDMI and control the skyrmion size. This work provides guidance to achieve\nsmaller N\\'{e}el-type skyrmions in Mn$_4$N thin films, which is an important\nstep forward for building thermally stable skyrmionic devices.",
        "positive": "Vibrational effects on low-temperature properties of molecular\n  conductors: We calculate characteristic correlation functions for the Anderson model with\nadditional phonon-assisted coupling to the odd conduction channel. This model\ndescribes, for example, the behavior of a molecule embedded between two\nelectrodes in linear transport experiments where the position of the molecule\nwith respect to the leads affects the tunneling amplitudes. We use variational\nprojection-operator method and numerical renormalization group (NRG) method.\nThe spin is Kondo screened either by even or odd conduction channel depending\non the gate voltage and electron-phonon coupling. However, in all regimes the\ngate-voltage dependence of the zero temperature conductance is found to be\nqualitatively the same as in the model with no coupling to the vibrational\nmode."
    },
    {
        "anchor": "Electric control of inverted gap and hybridization gap in type II\n  InAs/GaSb quantum wells: The quantum spin Hall effect has been predicted theoretically and observed\nexperimentally in InAs/GaSb quantum wells as a result of inverted band\nstructures, for which electron bands in InAs layers are below heavy hole bands\nin GaSb layers in energy. The hybridization between electron bands and heavy\nhole bands leads to a hybridization gap away from k=0. A recent puzzling\nobservation in experiments is that when the system is tuned to more inverted\nregime by a gate voltage (a larger inverted gap at k=0), the hybridization gap\ndecreases. Motivated by this experiment, we explore the dependence of\nhybridization gap as a function of external electric fields based on the\neight-band Kane model. We identify two regimes when varying electric fields:\n(1) both inverted and hybridization gaps increase and (2) inverted gap\nincreases while hybridization gap decreases. Based on the effective model, we\nfind that light-hole bands in GaSb layers play an important role in determining\nhybridization gap. In addition, a large external electric field can induce a\nstrong Rashba splitting and also influence hybridization gap.",
        "positive": "Mapping of few-electron wave-functions in semiconductor nanocrystals -\n  evidence of exchange interaction: The influence of the tip-substrate bias induced electric field in a\nscanning-tunneling-spectroscopy experiment on charged InAs nanocrystals is\nstudied. Calculating the ground and first excited many-particle state for five\nelectrons occupying the quantum dot reveals a Stark-induced reordering of\nstates by increasing the electric field strength. It is shown that this\nreordering of states is accompanied by a symmetry change of the local density\nof states (LDOS), which in principal is observable in a wave-function mapping\nexperiment. Since in the usually performed experiments the electric field can\nnot be directly controlled, we investigate the crystal size dependence of the\n5-electron LDOS symmetry. It is found that the symmetry changes from spherical\nto torus-like by increasing the nanocrystal radius."
    },
    {
        "anchor": "Circular dichroism in nanoparticle helices as a template for assessing\n  quantum-informed models in plasmonics: As characteristic lengths in plasmonics rapidly approach the sub-nm regime,\nquantum-informed models that can capture those aspects of the quantum nature of\nthe electron gas that are not accessible by the standard approximations of\nclassical electrodynamics, or even go beyond the free-electron description,\nbecome increasingly more important. Here we propose a template for comparing\nand validating the predictions of such models, through the circular dichroism\nsignal of a metallic nanoparticle helix. For illustration purposes, we compare\nthree widely used models, each dominant at different nanoparticle separations\nand governed by its own physical mechanism, namely the hydrodynamic Drude\nmodel, the generalised nonlocal optical response theory, and the\nquantum-corrected model for tunnelling. Our calculations show that indeed, each\ncase is characterised by a fundamentally distinctive response, always\ndissimilar to the predictions of the local optical response approximation of\nclassical electrodynamics, dominated by a model-sensitive absorptive\ndouble-peak feature. In circular dichroism spectra, the striking differences\nbetween models manifest themselves as easily traceable sign changes rather than\nneighbouring absorption peaks, thus overcoming experimental resolution\nlimitations and enabling efficient evaluation of the relevance, validity, and\nrange of applicability of quantum-informed theories for extreme-nanoscale\nplasmonics.",
        "positive": "Planar Hall torque: Spin-orbit torques in bilayers of ferromagnetic and nonmagnetic materials\nhold promise for energy efficient switching of magnetization in nonvolatile\nmagnetic memories. Previously studied spin Hall and Rashba torques originate\nfrom spin-orbit interactions within the nonmagnetic material and at the bilayer\ninterface, respectively. Here we report a spin-orbit torque that arises from\nplanar Hall current in the ferromagnetic material of the bilayer and acts as\neither positive or negative magnetic damping. This planar Hall torque exhibits\nunusual biaxial symmetry in the plane defined by the applied electric field and\nthe bilayer normal. The magnitude of the planar Hall torque is similar to that\nof the giant spin Hall torque and is large enough to excite auto-oscillations\nof the ferromagnetic layer magnetization."
    },
    {
        "anchor": "Fun with Quantum Dots: We consider quantum dots with a parabolic confining potential. The\nqualitative features of such mesoscopic systems as functions of the total\nnumber of electrons N and their total angular momentum J, e.g. magic numbers,\noverall symmetries etc., are derived solely from combinatoric principles. The\nkey is one simple hypothesis about such quantum dots yielding a basis of states\n(different from the usual single electron states one starts with) which is\nextremely easy to handle. Within this basis all qualitative features are\nalready present without the need of any perturbation theory.",
        "positive": "Time-reversal-invariant topological superconductivity: A topological superconductor is characterized by having a pairing gap in the\nbulk and gapless self-hermitian Majorana modes at its boundary. In one\ndimension, these are zero-energy modes bound to the ends, while in two\ndimensions these are chiral gapless modes traveling along the edge. Majorana\nmodes have attracted a lot of interest due to their exotic properties, which\ninclude non-abelian exchange statistics. Progress in realizing topological\nsuperconductivity has been made by combining spin-orbit coupling, conventional\nsuperconductivity, and magnetism. The existence of protected Majorana modes,\nhowever, does not inherently require the breaking of time-reversal symmetry by\nmagnetic fields. Indeed, pairs of Majorana modes can reside at the boundary of\na \\emph{time-reversal-invariant} topological superconductor (TRITOPS). It is\nthe time-reversal symmetry which then protects this so-called Majorana Kramers'\npair from gapping out. This is analogous to the case of the two-dimensional\ntopological insulator, with its pair of helical gapless boundary modes,\nprotected by time-reversal symmetry. Realizing the TRITOPS phase will be a\nmajor step in the study of topological phases of matter. In this paper we\ndescribe the physical properties of the TRITOPS phase, and review recent\nproposals for engineering and detecting them in condensed matter systems, in\none and two spatial dimensions. We mostly focus on extrinsic superconductors,\nwhere superconductivity is introduced through the proximity effect. We\nemphasize the role of interplay between attractive and repulsive\nelectron-electron interaction as an underlying mechanism. When discussing the\ndetection of the TRITOPS phase, we focus on the physical imprint of Majorana\nKramers' pairs, and review proposals of transport measurement which can reveal\ntheir existence."
    },
    {
        "anchor": "Fingerprints of anti-Pfaffian topological order in quantum point contact\n  transport: Despite recent experimental developments, the topological order of the\nfractional quantum Hall state at filling $\\nu=5/2$ remains an outstanding\nquestion. We study conductance and shot noise in a quantum point contact device\nin the charge-equilibrated regime and show that, among Pfaffian, particle-hole\nPraffian, and anti-Pfaffian (aPf) candidate states, the hole-conjugate aPf\nstate is unique in that it can produce a conductance plateau at $G=(7/3)e^2/h$\nby two fundamentally distinct mechanisms. We demonstrate that these mechanisms\ncan be distinguished by shot noise measurements on the plateaus. We also\ndetermine distinct features of the conductance of the aPf state in the coherent\nregime. Our results can be used to experimentally single out the aPf order.",
        "positive": "Effects of Fermi energy, dot size and leads width on weak localization\n  in chaotic quantum dots: Magnetotransport in chaotic quantum dots at low magnetic fields is\ninvestigated by means of a tight binding Hamiltonian on L x L clusters of the\nsquare lattice. Chaoticity is induced by introducing L bulk vacancies. The\ndependence of weak localization on the Fermi energy, dot size and leads width\nis investigated in detail and the results compared with those of previous\nanalyses, in particular with random matrix theory predictions. Our results\nindicate that the dependence of the critical flux Phi_c on the square root of\nthe number of open modes, as predicted by random matrix theory, is obscured by\nthe strong energy dependence of the proportionality constant. Instead, the size\ndependence of the critical flux predicted by Efetov and random matrix theory,\nnamely, Phi_c ~ sqrt{1/L}, is clearly illustrated by the present results. Our\nnumerical results do also show that the weak localization term significantly\ndecreases as the leads width W approaches L. However, calculations for W=L\nindicate that the weak localization effect does not disappear as L increases."
    },
    {
        "anchor": "Photo-induced spin and valley-dependent Seebeck effect in the\n  low-buckled Dirac materials: Employing the Landauer-Buttiker formula we investigate the spin and valley\ndependence of Seebeck effect in low-buckled Dirac materials (LBDMs), whose band\nstructure are modulated by local application of a gate voltage and off-resonant\ncircularly polarized light. We calculate the charge, spin and valley Seebeck\ncoefficients of an irradiated LBDM as functions of electronic doping, light\nintensity and the amount of the electric field in the linear regime. Our\ncalculation reveal that all Seebeck coefficients always shows an odd features\nwith respect to the chemical potential. Moreover, we show that, due to the\nstrong spin-orbit coupling in the LBDMs, the induced thermovoltage in the\nirradiated LBDMs is spin polarized, and can also become valley polarized if the\ngate voltage is applied too. It is also found that the valley (spin)\npolarization of the induced thermovoltage could be inverted by reversing the\ncircular polarization of light or reversing the direction the electric field\n(only by reversing the circular polarization of light).",
        "positive": "Unexpected large thermal rectification in asymmetric grain boundary of\n  graphene: We have investigated the lattice thermal transport across the asymmetric tilt\ngrain boundary between armchair and zigzag graphene by nonequilibrium molecular\ndynamics (NEMD). We have observed significant temperature drop and ultra-low\ntemperature-dependent thermal boundary resistance. More importantly, we find an\nunexpected thermal rectification phenomenon. The thermal conductivity and\nKapitza conductance is direction-dependent. The effect of thermal rectification\ncould be amplified by increasing the difference of temperature imposed on two\nsides. Our results propose a promising kind of thermal rectifier and phonon\ndiodes based on polycrystalline graphene without delicate manipulation of the\natomic structure."
    },
    {
        "anchor": "Memory effect preserved time-local approach to noise spectrum of\n  transport current: Within the second-order non-Markovian master equation description, we develop\nan efficient method for calculating the noise spectrum of transport current\nthrough interacting mesoscopic systems. By introducing proper current-related\ndensity operators, we propose a practical and very efficient time-local\napproach to compute the noise spectrum, including the asymmetric spectrum,\nwhich contains the full information of energy emission and absorption. We\nobtain an analytical formula of the current noise spectrum to characterize the\nnonequilibrium transport including electron-electron Coulomb interaction and\nthe memory effect. We demonstrate the proposed method in transport through\ninteracting-quantum-dots system, and find good agreement with the exact results\nunder broad range of parameters.",
        "positive": "Interplay between classical magnetic moments and superconductivity in\n  quantum one-dimensional conductors: toward a self-sustained topological\n  Majorana phase: We study a one-dimensional (1D) interacting electronic liquid coupled to a 1D\narray of classical magnetic moments and to a superconductor. We show that at\nlow energy and temperature the magnetic moments and the electrons become\nstrongly entangled and that a magnetic spiral structure emerges without any\nadjustable parameters. For strong enough coupling between the two, the 1D\nelectronic liquid is driven into a topological superconducting phase supporting\nMajorana fermions without any fine-tuning of external parameters. Our analysis\napplies at low enough temperature to a quantum wire in proximity of a\nsuperconductor when the hyperfine interaction between electrons and nuclear\nspins is taken into account or to a chain of magnetic adatoms adsorbed on a\nsuperconducting surface."
    },
    {
        "anchor": "Hartman effect for spin waves in exchange regime: Hartman effect for spin waves tunnelling through a barrier in a thin magnetic\nfilm is considered theoretically. The barrier is assumed to be created by a\nlocally increased magnetic anisotropy field. The considerations are focused on\na nanoscale system operating in the exchange-dominated regime. We derive the\nformula for group delay $\\tau_{gr}$ of spin wave package and show that\n$\\tau_{gr}$ saturates with increasing barrier width, which is a signature of\nthe Hartman effect predicted earlier for photonic and electronic systems. In\nour calculations we consider the general boundary exchange conditions which\ntake into account different strength of exchange coupling between the barrier\nand its surrounding. As a system suitable for experimental observation of the\nHartman effect we propose a CoFeB layer with perpendicular magnetic anisotropy\ninduced by a MgO overlayer.",
        "positive": "Moir\u00e9 superlattices in strained graphene-gold hybrid nanostructures: Graphene-metal nanoparticle hybrid materials potentially display not only the\nunique properties of metal nanoparticles and those of graphene, but also\nadditional novel properties due to the interaction between graphene and\nnanoparticles. This study shows that gold nanoislands can be used to tailor the\nlocal electronic properties of graphene. Graphene on crystalline gold\nnanoislands exhibits moir\\'e superlattices, which generate secondary Dirac\npoints in the local density of states. Conversely, the graphene covered gold\nregions undergo a polycrystalline to Au(111) phase transition upon annealing.\nMoreover, the nanoscale coexistence of moir\\'e superlattices with different\nmoir\\'e periodicities has also been revealed. Several of these moir\\'e\nperiodicities are anomalously large, which cannot be explained by the standard\nlattice mismatch between the graphene and the topmost Au(111) layers. Density\nfunctional theory and molecular dynamics simulations show for the first time\nthat in such cases the graphene and the interfacial metallic layer is strained,\nleading to distorted lattice constants, and consequently to reduced misfit.\nRoom temperature charge localization induced by a large wavelength moir\\'e\npattern is also observed by scanning tunneling spectroscopy. These findings can\nopen a route towards the strain engineering of graphene/metal interfaces with\nvarious moir\\'e superlattices and tailored electronic properties for nanoscale\ninformation coding."
    },
    {
        "anchor": "The effect of electron surface scattering on fine metal particle\n  electromagnetic radiation absorption: The magnetic dipole absorption cross section of a spherically shaped metal\nparticle was calculated in terms of kinetic approach. The particle considered\nwas placed in the field of a plane electromagnetic wave. The model of boundary\nconditions was investigated taking into account the dependence of the\nreflectivity coefficient both on the surface roughness parameter and on the\nelectron incidence angle. The results obtained were compared with theoretical\ncomputation results for a model of combined diffusion-specular boundary\nconditions of Fuchs.",
        "positive": "Limits of Validity of Rashba Model in BiTeI: A High-field\n  Magneto-optical Study: It was recently shown that BiTeI, a semiconductor with polar crystal\nstructure, possesses a giant spin-splitting of electrons, which has been\ninterpreted in terms of Rashba-type spin-orbit coupling. Here, we use high\nfield magneto-optical spectroscopy to quantify the deviations of the\nconduction-band profile from this appealing, but at the same time, strongly\nsimplifying model. We find that the optical response -- comprising a series of\ninter-Landau level excitations -- can be described by the Rashba model only at\nlow magnetic fields. In contrast, the high-field response appears to be more\nconsistent with a simple picture of massless electrons in a conical band. This\npoints towards more linear rather than parabolic at energies well above the\nbottom of the conduction band."
    },
    {
        "anchor": "Parameter-dependent unitary transformation approach for quantum Rabi\n  model: Quantum Rabi model has been exactly solved by employing the\nparameter-dependent unitary transformation method in both the occupation number\nrepresentation and the Bargmann space. The analytical expressions for the\ncomplete energy spectrum consisting of two double-fold degenerate sub-energy\nspectra are presented in the whole range of all the physical parameters. Each\nenergy level is determined by a parameter in the unitary transformation, which\nobeys a highly nonlinear equation. The corresponding eigenfunction is a\nconvergent infinite series in terms of the physical parameters. Due to the\nlevel crossings between the neighboring eigenstates at certain physical\nparameter values, such the degeneracies could lead to novel physical phenomena\nin the two-level system with the light-matter interaction.",
        "positive": "Nonequilibrium effective vector potential due to pseudospin exchange in\n  graphene: We show that exchange interactions in two-dimensional electron gases out of\nequilibrium can generate a fictitious vector potential with intriguing\nsignatures in interference and Hall measurements. Detailed predictions are made\nfor graphene, where the effect is enhanced by pseudospin exchange."
    },
    {
        "anchor": "Large Landau level splitting with tunable one-dimensional graphene\n  superlattice probed by magneto capacitance measurements: The unique zero energy Landau Level of graphene has a particle-hole symmetry\nin the bulk, which is lifted at the boundary leading to a splitting into two\nchiral edge modes. It has long been theoretically predicted that the splitting\nof the zero-energy Landau level inside the {\\it bulk} can lead to many\ninteresting physics, such as quantum spin Hall effect, Dirac like singular\npoints of the chiral edge modes, and others. However, so far the obtained\nsplitting with high-magnetic field even on a hBN substrate are not amenable to\nexperimental detection, and functionality. Guided by theoretical calculations,\nhere we produce a large gap zero-energy Landau level splitting ($\\sim$ 150 meV)\nwith the usage of a one-dimensional (1D) superlattice potential. We have\ncreated tunable 1D superlattice in a hBN encapsulated graphene device using an\narray of metal gates with a period of $\\sim$ 100 nm. The Landau level spectrum\nis visualized by measuring magneto capacitance spectroscopy. We monitor the\nsplitting of the zeroth Landau level as a function of superlattice potential.\nThe observed splitting energy is an order higher in magnitude compared to the\nprevious studies of splitting due to the symmetry breaking in pristine\ngraphene. The origin of such large Landau level spitting in 1D potential is\nexplained with a degenerate perturbation theory. We find that owing to the\nperiodic potential, the Landau level becomes dispersive, and acquires sharp\npeaks at the tunable band edges. Our study will pave the way to create the\ntunable 1D periodic structure for multi-functionalization and device\napplication like graphene electronic circuits from appropriately engineered\nperiodic patterns in near future.",
        "positive": "Fast and Ultrasensitive Electrometer Operating at the Single-Photon\n  Level: We demonstrate fast and ultrasensitive charge detection with a\ncavity-embedded Cooper pair transistor (cCPT) via dispersive readout of its\nJosephson inductance. We report a minimum charge sensitivity of $14$ $\\mu\ne/\\sqrt{\\mathrm{Hz}}$ with a detection bandwidth on the order of $1$ MHz using\n$16$ attowatts of power, corresponding to the single-photon level of the\ncavity. In addition, our measured sensitivities are within a factor of $5$ of\nthe quantum limit for this device. The single-photon-level sensitivity of the\ncCPT is comparable to that of the rf-SET, which typically operates using\npicowatts of power corresponding to hundreds of thousands of photons in its\ntank circuit. Our results support the feasibility of using the cCPT to mediate\nan optomechanical interaction that reaches the single-photon strong coupling\nregime."
    },
    {
        "anchor": "Magnetic field induced Valley-Polarized Quantum Anomalous Hall Effects\n  in Ferromagnetic van der Waals Heterostructures: The valley-polarized quantum anomalous Hall effect (VQAHE) attracts intensive\ninterest since it uniquely combines valleytronics and spintronics with\nnontrivial band topology. Here, based on first-principles calculations and\nWannier-function-based tight-binding (WFTB) model, we reveal that valley-based\nHall effects and especially the VQAHE induced by external magnetic fields can\noccur in two-dimensional (2D) ferromagnetic van der Waals heterostructures\n(vdWHs). The results show that considerable valley-splitting derived from the\nZeeman exchange energy drives these vdWHs generating the valley anomalous Hall\neffect and then the VQAHE. The chiral edge states and quantized Hall\nconductance are utilized to confirm the presence of VQAHE. Besides, it is also\nfound that external electric fields (or tuning interlayer distances) can\nfacilitate the realization of VQAHE, and thus we present a phase diagram in a\nbroad parameter regime of magnetic fields and electric fields (or interlayer\ndistances). Our work not only offers a class of ferromagnetic vdWHs to realize\nvarious valley-based Hall phases, but also can guide advancements for designing\ntopological devices with spin-valley filtering effects based on the VQAHE.",
        "positive": "Comprehensive numerical modeling of filamentary RRAM devices including\n  voltage ramp-rate and cycle-to-cycle variations: The equilibrium ON and OFF states of resistive random access memory (RRAM)\nare due to formation and destruction of a conducting filament. The laws of\nthermodynamics dictate that these states correspond to the minimum of free\nenergy. Here, we develop a numerical model that, through the minimization of\nfree energy at a given voltage, determines the filament parameters and thus the\nelectric current. Overall, it simulates the current-voltage (I-V)\ncharacteristics of RRAM. The model describes mutual transformations of RRAM\nstates through SET (ON to OFF) and RESET (OFF to ON) processes. From the\nmodeling perspectives, these states and processes constitute four programming\nmodules constructed here in COMSOL Multiphysics software tackling the\nelectrodynamic and heat transfer equations and yielding RRAM energy and I-V.\nOur modeling uniquely reproduces the observed I-V varying with voltage\nramp-rates. That is achieved by accounting for the ramp-rate dependent\nactivation energy of conduction. The underlying mechanism is due to the\ndeformation interaction caused by the double well atomic potentials universally\npresent in amorphous materials and having exponentially broad distribution of\nrelaxation times. As another unique feature, our modeling reproduces the\nobserved cycle-to-cycle variations of RRAM parameters attributed to the lack of\nself-averaging in small ensembles of double well potentials and electronic\nstates in geometrically small (nano-size) RRAM structures."
    },
    {
        "anchor": "Chiral magnetic domain walls under transverse fields: a semi-analytical\n  model: An analytical model for the domain wall structure in ultrathin films with\nperpendicular easy axis and interfacial Dzyaloshinskii-Moriya interaction,\nsubmitted to an arbitrary in-plane magnetic field, is presented. Its solution\nis simplified to the numerical minimization of an analytic function of just one\nvariable. The model predictions are compared to numerical micromagnetic\nsimulations, using parameters of existing samples, revealing a very good\nagreement. Remaining differences are analyzed, and partly corrected.\nDifferences with the predictions of the simplest model, usually found in the\nliterature, in which only the domain wall moment's in-plane orientation can\nvary, are exemplified. The model allows accurate computations, as a function of\nin-plane field module and orientation, of the domain wall tension and width,\nquantities controlling the creep motion of domain walls in such films.",
        "positive": "Single-shot measurement and tunnel-rate spectroscopy of a Si/SiGe\n  few-electron quantum dot: We investigate the tunnel rates and energies of excited states of small\nnumbers of electrons in a quantum dot fabricated in a Si/SiGe heterostructure.\nTunnel rates for loading and unloading electrons are found to be strongly\nenergy dependent, and they vary significantly between different excited states.\nWe show that this phenomenon enables charge sensing measurements of the average\nelectron occupation that are analogous to Coulomb diamonds. Excited-state\nenergies can be read directly from the plot, and we develop a rate model that\nenables a quantitative understanding of the relative sizes of different\nelectron tunnel rates."
    },
    {
        "anchor": "Spin-charge separation in Quantum Hall Liquids: We have investigated chiral edges of a quantum Hall(QH) liquid at filling\nfactor \\nu=2. We find that spin and charge separate in the presence of the\nlong-range Coulomb interaction, and the tunneling density of states(DOS) is\ngiven by D(\\omega)\\sim [-1/\\ln\\omega]^{1/2}. The measurement of the temperature\nand voltage dependences of the tunneling current should reveal the presence\nspin-charge separation.",
        "positive": "Symmetry-Protected Solitons and Bulk-Boundary Correspondence in\n  Generalized Jackiw-Rebbi Models: We investigate the roles of symmetry and bulk-boundary correspondence in\ncharacterizing topological edge states in generalized Jackiw-Rebbi (JR) models.\nWe show that time-reversal ($T$), charge-conjugation ($C$), parity ($P$), and\ndiscrete internal field rotation ($Z_n$) symmetries protect and characterize\nthe various types of edge states such as chiral and nonchiral solitons via\nbulk-boundary correspondence in the presence of the multiple vacua. As two\nrepresentative models, we consider the JR model composed of a single fermion\nfield having a complex mass and the generalized JR model with two massless but\ninteracting fermion fields. The JR model shows nonchiral solitons with the\n$Z_2$ rotation symmetry, whereas it shows chiral solitons with the broken $Z_2$\nrotation symmetry. In the generalized JR model, only nonchiral solitons can\nemerge with only $Z_2$ rotation symmetry, whereas both chiral and nonchiral\nsolitons can exist with enhanced $Z_4$ rotation symmetry. Moreover, we find\nthat the nonchiral solitons have $C, P$ symmetries while the chiral solitons do\nnot, which can be explained by the symmetry-invariant lines connecting\ndegenerate vacua. Finally, we find the symmetry correspondence between\nmultiply-degenerate global vacua and solitons such that ${T}$, ${C}$, ${P}$\nsymmetries of a soliton inherit from global minima that are connected by the\nsoliton, which provides a novel tool for the characterization of topological\nsolitons."
    },
    {
        "anchor": "Theory of zero-field superconducting diode effect in twisted trilayer\n  graphene: In a recent experiment [Lin et al., arXiv:2112.07841], the superconducting\nphase hosted by a heterostructure of mirror-symmetric twisted trilayer graphene\nand WSe$_2$ was shown to exhibit significantly different critical currents in\nopposite directions in the absence of external magnetic fields. We here develop\na microscopic theory and analyze necessary conditions for this zero-field\nsuperconducting diode effect. Taking into account the spin-orbit coupling\ninduced in trilayer graphene via the proximity effect, we classify the pairing\ninstabilities and normal-state orders and derive which combinations are\nconsistent with the observed diode effect, in particular, its field\ntrainability. We perform explicit calculations of the diode effect in several\ndifferent models, including the full continuum model for the system, and\nilluminate the relation between the diode effect and finite-momentum pairing.\nOur theory also provides a natural explanation of the observed sign change of\nthe current asymmetry with doping, which can be related to an approximate\nchiral symmetry of the system, and of the enhanced transverse resistance above\nthe superconducting transition. Our findings not only elucidate the rich\nphysics of trilayer graphene on WSe$_2$, but also establish a means to\ndistinguish between various candidate interaction-induced orders in\nspin-orbit-coupled graphene moir\\'e systems, and could therefore serve as a\nguide for future experiments as well.",
        "positive": "Determination of intrinsic damping of perpendicularly magnetized\n  ultrathin films from time resolved precessional magnetization measurements: Magnetization dynamics are strongly influenced by damping. An effective\ndamping constant {\\alpha}eff is often determined experimentally from the\nspectral linewidth of the free induction decay of the magnetization after the\nsystem is excited to its non-equilibrium state. Such an {\\alpha}eff, however,\nreflects both intrinsic damping as well as inhomogeneous broadening. In this\npaper we compare measurements of the magnetization dynamics in ultrathin\nnon-epitaxial films having perpendicular magnetic anisotropy using two\ndifferent techniques, time-resolved magneto optical Kerr effect (TRMOKE) and\nhybrid optical-electrical ferromagnetic resonance (OFMR). By using an external\nmagnetic field that is applied at very small angles to the film plane in the\nTRMOKE studies, we develop an explicit closed-form analytical expression for\nthe TRMOKE spectral linewidth and show how this can be used to reliably extract\nthe intrinsic Gilbert damping constant. The damping constant determined in this\nway is in excellent agreement with that determined from the OFMR method on the\nsame samples. Our studies indicate that the asymptotic high-field approach that\nis often used in the TRMOKE method to distinguish the intrinsic damping from\nthe effective damping may result in significant error, because such high\nexternal magnetic fields are required to make this approach valid that they are\nout of reach. The error becomes larger the lower is the intrinsic damping\nconstant, and thus may account for the anomalously high damping constants that\nare often reported in TRMOKE studies. In conventional ferromagnetic resonance\n(FMR) studies, inhomogeneous contributions can be readily distinguished from\nintrinsic damping contributions from the magnetic field dependence of the FMR\nlinewidth. Using the analogous approach, we show how reliable values of the\nintrinsic damping can be extracted from TRMOKE."
    },
    {
        "anchor": "Quantization Of Cyclotron Motion and Quantum Hall Effect: We present a two dimensional model of IQHE in accord with the cyclotron\nmotion. The quantum equation of the QHE curve and a new definition of filling\nfactor are also given.",
        "positive": "Perfect transmission at oblique incidence by trigonal warping in\n  graphene P-N junctions: We develop an analytical mode-matching technique for the tight-binding model\nto describe electron transport across graphene P-N junctions. This method\nshares the simplicity of the conventional mode-matching technique for the\nlow-energy continuum model and the accuracy of the tight-binding model over a\nwide range of energies. It further reveals an interesting phenomenon on a sharp\nP-N junction: the disappearance of the well-known Klein tunneling (i.e.,\nperfect transmission) at normal incidence and the appearance of perfect\ntransmission at oblique incidence due to trigonal warping at energies beyond\nthe linear Dirac regime. We show that this phenomenon arises from the\nconservation of a generalized pseudospin in the tight-binding model. We expect\nthis effect to be experimentally observable in graphene and other Dirac\nfermions systems, such as the surface of three-dimensional topological\ninsulators."
    },
    {
        "anchor": "Dynamical instabilities of a resonator driven by a superconducting\n  single-electron transistor: We investigate the dynamical instabilities of a resonator coupled to a\nsuperconducting single-electron transistor (SSET) tuned to the Josephson\nquasiparticle (JQP) resonance. Starting from the quantum master equation of the\nsystem, we use a standard semiclassical approximation to derive a closed set of\nmean field equations which describe the average dynamics of the resonator and\nSSET charge. Using amplitude and phase coordinates for the resonator and\nassuming that the amplitude changes much more slowly than the phase, we explore\nthe instabilities which arise in the resonator dynamics as a function of\ncoupling to the SSET, detuning from the JQP resonance and the resonator\nfrequency. We find that the locations (in parameter space) and sizes of the\nlimit cycle states predicted by the mean field equations agree well with\nnumerical solutions of the full master equation for sufficiently weak\nSSET-resonator coupling. The mean field equations also give a good qualitative\ndescription of the set of dynamical transitions in the resonator state that\noccur as the coupling is progressively increased.",
        "positive": "Visualizing \"Fermi arcs\" in the Weyl semimetal TaAs: One of the hallmarks of Weyl semi-metals is the existence of unusual\ntopological surface states known as 'Fermi arcs' [1-3]. The formation of these\nstates is guaranteed by the existence of bulk Weyl points with opposite\nchirality. Tantalum Arsenide (TaAs) [4-9], a member of the newly discovered\nfamily of Weyl semi-metals [4,5], harbors a host of non-topological ('trivial')\nsurface states overlapping in energy with the predicted 12 'Fermi arcs'. This\noverlap poses a major challenge in identifying the signatures of the arcs [10].\nHere we harness the inherently distinct spatial structure of trivial and Fermi\narc states to visualize the Fermi arcs for the first time using scanning\ntunneling microscopy. We do so in four distinct ways, each of which highlights\na different aspect of their unusual nature. We reveal their relatively\nisotropic scattering signature, their energy dispersion and its relation to the\nbulk Weyl points, their deep bulk penetration relative to that of\nnon-topological surface states and their weak coupling to the atomic structure.\nThe latter is obtained by accounting for the spatial structure of the Bloch\nwavefunction and its effect on the scattering properties of the electrons off\nlattice defects in general. It thus provides a novel analysis tool for the\nspectroscopic characterization of electronic wavefunctions using scanning\ntunneling microscopy."
    },
    {
        "anchor": "A(nother) Continuum Model for Dephasing in Mesoscopic Systems: A dephasing model in the spirit of Buttiker's fictitious probe model where\ninfinite probes are distributed uniformly over the conductor is proposed. The\ndephasing rate enters into the model as an adjustable parameter and to compute\nthe conductance. A one-dimensional delta function scatterer model is solved\nnumerically. We observe the dephasing effects on the calculated conductance.",
        "positive": "Near-field radiative heat transfer between nanostructures in the deep\n  sub-wavelength regime: Radiative heat transfer between parallel objects separated by deep\nsub-wavelength distances and subject to large thermal gradients (>100 K) could\nenable breakthrough technologies for electricity generation and thermal\ntransport control. However, thermal transport in this regime has never been\nachieved experimentally due to the difficulty of maintaining large thermal\ngradients over nm-scale distances while avoiding other heat transfer mechanism\nsuch as conduction. Previous experimental measurement between parallel planes\nwere limited to distances greater than 500 nm (with a 20 K thermal gradient),\nwhich is much larger than the theoretically predicted distance (<100 nm)\nrequired for most applications. Here we show near-field radiative heat transfer\nbetween parallel nanostructures in the deep sub-wavelength regime using high\nprecision micro electromechanical (MEMS) displacement control. We also exploit\nthe high mechanical stability of structures under high tensile stress to\nminimize thermal buckling effects and maintain small separations at large\nthermal gradients. We achieve an enhancement of heat transfer of almost two\norders of magnitude relative to the far-field limit, which corresponds to a 54\nnm separation. We also achieve a high temperature gradient (260 K) between the\ncold and hot surfaces while maintaining a ~100 nm distance."
    },
    {
        "anchor": "Laser-induced magnonic band gap formation and control in YIG/GaAs\n  heterostructure: We demonstrate the laser-induced control over spin-wave (SW) transport in the\nmagnonic crystal (MC) waveguide formed from the semiconductor slab placed on\nthe ferrite film. We considered bilayer MC with periodical grooves performed on\nthe top of the n-type gallium arsenide slab side that oriented to the yttrium\niron garnet film. To observe the appearance of magnonic gap induced by laser\nradiation, the fabricated structure was studied by the use of microwave\nspectroscopy and Brillouin light-scattering. We perform detailed numerical\nstudies of this structure. We showed that the optical control of the magnonic\ngaps (frequency width and position) is related to the variation of the charge\ncarriers' concentration in GaAs. We attribute these to nonreciprocity of SW\ntransport in the layered structure. Nonreciprocity was induced by the laser\nexposure of the GaAs slab due to SWs' induced electromagnetic field screening\nby the optically-generated charge carriers. We showed that SW dispersion,\nnonreciprocity, and magnonic band gap position and width in the\nferrite-semiconductor magnonic crystal can be modified in a controlled manner\nby laser radiation. Our results show the possibility of the integration of\nmagnonics and semiconductor electronics on the base of YIG/GaAs structures.",
        "positive": "Carbon nanotubes with atomic impurities on boron nitride sheets under\n  applied electric fields: We perform first-principles calculations to investigate the structural and\nelectronic properties of metal-doped (10, 0) carbon nanotubes (CNTs) on a\nsingle hexagonal boron nitride (hBN) sheet in the presence of an external\nelectric field. We consider K, Cl and Ni atoms as dopants to study the\ndependence of the electronic properties of the CNT on doping polarity and\nconcentration. The electric field strength is varied from -0.2 V/\\AA to +0.2\nV/\\AA to explore the effects of an external electric field on the electronic\nstructures. Although the electronic energy bands of the hBN sheet are modified\nin accordance with the field strength, its electronic state in the valence or\nconduction band does not touch the Fermi level under the field strength\nconsidered. We conclude that the hBN as a substrate does not modify the\nelectronic structure of the CNT, thereby leading to improvements in the device\nperformance, compared with that of devices based on conventional substrate\nmaterials such as SiO$_2$."
    },
    {
        "anchor": "0-$\u03c0$ quantum transition in a carbon nanotube Josephson junction:\n  universal phase dependence and orbital degeneracy: We investigate experimentally the supercurrent in a clean carbon nanotube\nquantum dot, close to orbital degeneracy, connected to superconducting leads in\na regime of strong competition between local electronic correlations and\nsuperconducting proximity effect. For an odd occupancy of the dot and\nintermediate coupling to the reservoir, the Kondo effect can develop in the\nnormal state and screen the local magnetic moment of the dot. This leads to\nsinglet-doublet transitions that strongly affect the Josephson effect in a\nsingle-level quantum dot: the sign of the supercurrent changes from positive to\nnegative (0 to $\\pi$-junction). In the regime of strongest competition between\nthe Kondo effect and proximity effect, meaning that the Kondo temperature\nequals the superconducting gap, the magnetic state of the dot undergoes a first\norder quantum transition induced by the superconducting phase difference across\nthe junction. This is revealed experimentally by anharmonic current-phase\nrelations. In addition, the very specific electronic configuration of clean\ncarbon nanotubes, with two nearly orbitally degenerated states, leads to\ndifferent physics depending whether only one or both quasi-degenerate upper\nlevels of the dots participate to transport, which is determined by their\noccupancy and relative widths. When the transport of Cooper pairs takes place\nthrough only one of these levels, we find that the phase diagram of the\nphase-dependent 0-$\\pi$ transition is a universal characteristic of a\ndiscontinuous level-crossing quantum transition at zero temperature. In the\ncase were two levels participate to transport, the nanotube Josephson current\nexhibits a continuous 0-$\\pi$ transition, independent of the superconducting\nphase, revealing a different physical mechanism of the transition.",
        "positive": "High-Harmonic Generation from Engineered Graphene for Polarization\n  Tailoring: Strain engineering is a versatile method to boost the carrier mobility of\ntwo-dimensional materials-based electronics and optoelectronic devices. In\naddition, strain is ubiquitous during device fabrication via material\ndeposition on a substrate with a different lattice structure. Here, we show\nthat the polarization properties of the harmonics in graphene under uniaxial\nstrain are strongly yet differently affected in the lower and higher orders.\nThe polarization plane of the lower-order emitted harmonics is rotated -- a\nmanifestation of Faraday rotation due to the broken symmetry planes. In\ncontrast, we observe elliptically-polarized higher-order harmonics due to the\nintricate interplay of the interband and intraband electron dynamics. The\nimplications of these findings are twofold: First, we show how the rotation of\nthe polarization plane of the lower-order harmonics can be used as a probe to\ncharacterize the strain's nature, strength, and angle. Second, we demonstrate\nhow strain engineering can be used to alter the polarization properties of\nhigher-order harmonics, relevant for applications in ultrafast chiral-sensitive\nstudies. Our research opens a promising avenue for strain-tailored polarization\nproperties of higher-order harmonics in engineered solids."
    },
    {
        "anchor": "Probing the topological character of superconductors via non-local\n  Hanbury-Brown and Twiss correlations: Superconductors can be classified as topological or not based on whether\ntime-reversal symmetry (TRS), chiral symmetry, and particle-hole symmetry are\npreserved or not. Further, topological superconductors can also be classified\nas chiral or helical. In this paper, using Hanbury-Brown and Twiss (HBT) shot\nnoise correlations and the non-local conductance, we probe metal/2D\nunconventional superconductor/metal junctions to understand better the pairing\ntopological vs. non-topological or helical vs. chiral or nodal vs. gapful. We\nsee that HBT correlations are asymmetric as a function of bias voltage for\nnon-topological superconductors, whereas they are symmetric for topological\nsuperconductors irrespective of the barrier strength. Topological\nsuperconductors are associated with Majorana fermions which are important for\ntopological quantum computation. By distinguishing topological superconductors\nfrom non-topological superconductors, our study will help search for Majorana\nfermions, which will aid in designing a topological quantum computer.",
        "positive": "Room temperature de Haas - van Alphen effect in silicon nanosandwiches: The negative-U impurity stripes confining the edge channels of semiconductor\nquantum wells are shown to allow the effective cooling inside in the process of\nthe spin-dependent transport. The aforesaid promotes also the creation of\ncomposite bosons and fermions by the capture of single magnetic flux quanta on\nthe edge channels under the conditions of low sheet density of carriers, thus\nopening new opportunities for the registration of the quantum kinetic phenomena\nin weak magnetic fields at high temperatures up to the room temperature. As a\ncertain version noted above we present the first findings of the high\ntemperature de Haas-van Alphen, 300K, and quantum Hall, 77K, effects in the\nsilicon sandwich structure that represents the ultra-narrow, 2 nm, p-type\nquantum well (Si-QW) confined by the delta barriers heavily doped with boron on\nthe n-type Si (100) surface. These data appear to result from the low density\nof single holes that are of small effective mass in the edge channels of p-type\nSi-QW because of the impurity confinement by the stripes consisting of the\nnegative-U dipole boron centers which seems to give rise to the efficiency\nreduction of the electron-electron interaction."
    },
    {
        "anchor": "Magnetic properties of nanoparticles in the Bethe-Peierls approximation: In this work we present a new method to calculate the classical properties of\nmagnetic nanoparticles. Based on the Bethe-Peierls (pair) approximation, we\ndeveloped a simple system of equations for the classical magnetization of spins\nat any position within the nanoparticle. The nearest neightbor pair\ncorrelations are treated exactly for Ising spins, and the method can be\ngeneralized for various lattice symmetries. The master equation is solved for\nthe Glauber dynamics (single-spin-flip) in order to obtain the time evolution\nof the magnetization. The capabilities of the model are demonstrated through\nthe calculation of hysteresis loops as well as field cooling (FC) and zero\nfield cooling (ZFC) magnetization curves of heterogeneous nanoparticles. The\npresent method can be an alternative to the usually complex and time consuming\nmethods employed in micromagnetism.",
        "positive": "Landau Quantization and Highly Mobile Fermions in an Insulator: In strongly correlated materials, quasiparticle excitations can carry\nfractional quantum numbers. An intriguing possibility is the formation of\nfractionalized, charge-neutral fermions, e.g., spinons and fermionic excitons,\nthat result in neutral Fermi surfaces and Landau quantization in an insulator.\nWhile previous experiments in quantum spin liquids, topological Kondo\ninsulators, and quantum Hall systems have hinted at charge-neutral Fermi\nsurfaces, evidence for their existence remains far from conclusive. Here we\nreport experimental observation of Landau quantization in a two dimensional\n(2D) insulator, i.e., monolayer tungsten ditelluride (WTe$_{2}$), a large gap\ntopological insulator. Using a detection scheme that avoids edge contributions,\nwe uncover strikingly large quantum oscillations in the monolayer insulator's\nmagnetoresistance, with an onset field as small as ~ 0.5 tesla. Despite the\nhuge resistance, the oscillation profile, which exhibits many periods, mimics\nthe Shubnikov-de Haas oscillations in metals. Remarkably, at ultralow\ntemperatures the observed oscillations evolve into discrete peaks near 1.6\ntesla, above which the Landau quantized regime is fully developed. Such a low\nonset field of quantization is comparable to high-mobility conventional\ntwo-dimensional electron gases. Our experiments call for further investigation\nof the highly unusual ground state of the WTe$_{2}$ monolayer. This includes\nthe influence of device components and the possible existence of mobile\nfermions and charge-neutral Fermi surfaces inside its insulating gap."
    },
    {
        "anchor": "Transmission Phase of an Isolated Coulomb-Blockade Resonance: In two recent papers, O. Entin-Wohlman et al. studied the question: ``Which\nphysical information is carried by the transmission phase through a quantum\ndot?'' In the present paper, this question is answered for an islolated\nCoulomb-blockade resonance and within a theoretical model which is more closely\npatterned after the geometry of the actual experiment by Schuster et al. than\nis the model of O. Entin-Wohlman et al. We conclude that whenever the number of\nleads coupled to the Aharanov-Bohm interferometer is larger than two, and the\ntotal number of channels is sufficiently large, the transmission phase does\nreflect the Breit-Wigner behavior of the resonance phase shift.",
        "positive": "Effect of localizing groups on electron transport through single\n  conjugated molecules: Electron transport properties through single conjugated molecules sandwiched\nbetween two non-superconducting electrodes are studied by the use of Green's\nfunction technique. Based on the tight-binding model, we do parametric\ncalculations to characterize the electron transport through such molecular\nbridges. The electron transport properties are significantly influenced by (a)\nthe existence of localizing groups in these conjugated molecules and (b) the\nmolecule to electrode coupling strength, and, here we focus our results in\nthese two aspects."
    },
    {
        "anchor": "Density Induced Interchange of Anisotropy Axes at Half-Filled High\n  Landau Levels: We observe density induced 90$^{\\circ}$ rotations of the anisotropy axes in\ntransport measurements at half-filled high Landau levels in the two dimensional\nelectron system, where stripe states are proposed ($\\nu$=9/2, 11/2, etc). Using\na field effect transistor, we find the transition density to be\n$2.9\\times10^{11}$cm$^{-2}$ at $\\nu$=9/2. Hysteresis is observed in the\nvicinity of the transition. We construct a phase boundary in the filling\nfactor-magnetic field plane in the regime $4.4<\\nu<4.6$. An in-plane magnetic\nfield applied along either anisotropy axis always stabilizes the low density\norientation of the stripes.",
        "positive": "Magnetoconductance noise and irreversibilities in submicron wires of\n  spin-glass n-CdMnTe: Signatures of spin-glass freezing such as the appearance of 1/f conductance\nnoise, the recovery of universal conductance fluctuations, aging, as well as\nmagnetic and thermal irreversibilities are detected in mesoscopic wires of\nCdMnTe:I at millikelvin temperatures. Spectral characteristics of conductance\ntime series are consistent with the droplet model of short-range spin-glasses."
    },
    {
        "anchor": "Phase diagram and optimal switching induced by spin Hall effect in a\n  perpendicular magnetic layer: In a ferromagnet/heavy-metal bilayer device with strong spin Hall effect an\nin-plane current excites magnetic dynamics through spin torque. We analyze\nbilayers with perpendicular magnetization and calculate three-dimensional phase\ndiagrams describing switching by external magnetic field at a fixed current. We\nthen concentrate on the case of a field applied in the plane formed by the film\nnormal and the current direction. Here we analytically study the evolution of\nboth the conventional \"up\"/\"down\" magnetic equilibria and the additional\nequilibria created by the spin torque. Expressions for the stability regions of\nall equilibria are derived, and the nature of switching at each critical\nboundary is discussed. The qualitative picture obtained this way predicts\ncomplex hysteresis patterns that should occur in bilayers. By analyzing the\nphase portraits of the system we show that when the spin torque induced\nequilibrium exists, switching between \"up\" and \"down\" states proceeds through\nit as an intermediate state. Using numeric simulations we analyze the switching\ntime and compare it to that of a conventional spin torque device with collinear\nmagnetizations of the polarizer and the free layer.",
        "positive": "Infrared light emission from atomic point contacts: Gold atomic point contacts are prototype systems to evidence ballistic\nelectron transport. The typical dimension of the nanojunction being smaller\nthan the electron-phonon interaction length, even at room temperature,\nelectrons transfer their excess energy to the lattice only far from the\ncontact. At the contact however, favored by huge current densities,\nelectron-electron interactions result in a nano hot electron gas acting as a\nsource of photons. Using a home built Mechanically Controlled Break Junction,\nit is reported here, for the first time, that this hot electron gas also\nradiates in the infrared range (0.2eV to 1.2eV). Moreover, in agreement with\nthe pioneering work of Tomchuk, we show that this radiation is compatible with\na blackbody like spectrum emitted from an electron gas at temperatures of\nseveral thousands of Kelvin given by $(kB.Te)^2 = \\alpha. I.V$ where $\\alpha$,\n$I$ and $V$ are respectively a fitting parameter, the current flowing and the\napplied bias."
    },
    {
        "anchor": "Control of Spin Diffusion and Suppression of the Hanle Effect by the\n  Coexistence of Spin and Valley Hall Effects: In addition to spin, electrons in many materials possess an additional\npseudo-spin degree of freedom known as 'valley'. In materials where the spin\nand valley degrees of freedom are weakly coupled, they can be both excited and\ncontrolled independently. In this work, we study a model describing the\ninterplay of the spin and valley Hall effects in such two-dimensional\nmaterials. We demonstrate the emergence of an additional longitudinal neutral\ncurrent that is both spin and valley polarized. The additional neutral current\nallows to control the spin density by tuning the magnitude of the valley Hall\neffect. In addition, the interplay of the two effects can suppress the Hanle\neffect, that is, the oscillation of the nonlocal resistance of a Hall bar\ndevice with in-plane magnetic field. The latter observation provides a possible\nexplanation for the absence of the Hanle effect in a number of recent\nexperiments. Our work opens also the possibility to engineer the conversion\nbetween the valley and spin degrees of freedom in two-dimensional materials.",
        "positive": "Correlation and dephasing effects on the non-radiative coherence between\n  bright excitons in an InAs QD ensemble measured with 2D spectroscopy: Exchange-mediated fine-structure splitting of bright excitons in an ensemble\nof InAs quantum dots is studied using optical two-dimensional Fourier-transform\nspectroscopy. By monitoring the non-radiative coherence between the bright\nstates, we find that the fine-structure splitting decreases with increasing\nexciton emission energy at a rate of 0.1 $\\mu$eV/meV. Dephasing rates are\ncompared to population decay rates to reveal that pure dephasing causes the\nexciton optical coherences to decay faster than the radiative limit at low\ntemperature, independent of excitation density. Fluctuations of the bright\nstate transition energies are nearly perfectly-correlated, protecting the\nnon-radiative coherence from interband dephasing mechanisms."
    },
    {
        "anchor": "Emergence of the stripe-domain phase in patterned Permalloy films: The occurrence of stripe domains in ferromagnetic Permalloy\n(Py=Fe$_{20}$Ni$_{80}$) is a well known phenomenon which has been extensively\nobserved and characterized. This peculiar magnetic configuration appears only\nin films with a thickness above a critical value ($d_{cr}$), which is strongly\ndetermined by the sputtering conditions (i.e. deposition rate, temperature,\nmagnetic field). So far, $d_{cr}$ has usually been presented as the boundary\nbetween the homogeneous (H) and stripe-domains (SD) regime, respectively below\nand above $d_{cr}$. In this work we study the transition from the H to the SD\nregime in thin films and microstructured bridges of Py with different\nthicknesses. We find there is an intermediate regime, over a quite significant\nthickness range below d$_{cr}$, which is signaled in confined structures by a\nquickly changing domain-wall configuration and by a broadening of the\nmagnetoresistance dip at the coercive field. We call this the emerging\nstripe-domains (ESD) regime. The transition from the ESD to the SD regime is\naccompanied by a sharp increase of the magnetoresistance ratio at the thickness\nwhere stripes appear in MFM.",
        "positive": "Ordered Dissipative Structures in Exciton Systems in Semiconductor\n  Quantum Wells: A phenomenological theory of exciton condensation in conditions of\ninhomogeneous excitation is proposed. The theory is applied to the study of the\ndevelopment of an exciton luminescence ring and the ring fragmentation at\nmacroscopical distances from the central excitation spot in coupled quantum\nwells. The transition between the fragmented and the continuous ring is\nconsidered. With assumption of a defect in the structure, a possibility of a\nlocalized island of the condensed phase in a fixed position is shown. Exciton\ndensity distribution is also analyzed in the case of two spatially separated\nspots of the laser excitation."
    },
    {
        "anchor": "Exploiting Coherence in Nonlinear Spin-Superfluid Transport: We show how the interference between superfluid spin currents can endow spin\ncircuits with coherent logic functionality. While the hydrodynamic aspects of\nthe linear-response collective spin transport obviate interference features, we\nfocus on the nonlinear regime, where the critical supercurrent is sensitive to\nthe phase accumulated by the condensate in a loop geometry. We propose to\ncontrol this phase by electrical gating, tuning the spin-condensate coherence\nlength. The nonlinear aspects of the spin superfluidity thus naturally lend\nthemselves to the construction of logic gates, uniquely exploiting the\ncoherence of collective spin currents. Vice versa, this functionality can be\nused to reveal the fundamental properties of spin superfluids.",
        "positive": "Low-Noise GaAs Quantum Dots for Quantum Photonics: Quantum dots are both excellent single-photon sources and hosts for single\nspins. This combination enables the deterministic generation of Raman-photons\n-- bandwidth-matched to an atomic quantum-memory -- and the generation of\nphoton cluster states, a resource in quantum communication and\nmeasurement-based quantum computing. GaAs quantum dots in AlGaAs can be matched\nin frequency to a rubidium-based photon memory, and have potentially improved\nelectron spin coherence compared to the widely used InGaAs quantum dots.\nHowever, their charge stability and optical linewidths are typically much worse\nthan for their InGaAs counterparts. Here, we embed GaAs quantum dots into an\n$n$-$i$-$p$-diode specially designed for low-temperature operation. We\ndemonstrate ultra-low noise behaviour: charge control via Coulomb blockade,\nclose-to lifetime-limited linewidths, and no blinking. We observe high-fidelity\noptical electron-spin initialisation and long electron-spin lifetimes for these\nquantum dots. Our work establishes a materials platform for low-noise quantum\nphotonics close to the red part of the spectrum."
    },
    {
        "anchor": "Nodal vacancy bound states and resonances in three-dimensional Weyl\n  semimetals: The electronic structure of a cubic $\\mathcal{T}$-symmetric Weyl semimetal is\nanalysed in the presence of atomic-sized vacancy defects. Isolated vacancies\nare shown to generate nodal bound states with $r^{{\\scriptscriptstyle -2}}$\nasymptotic tails, even when immersed in a weakly disordered environment. These\nstates show up as a significantly enhanced nodal density of states which, as\nthe concentration of defects is increased, reshapes into a nodal peak that is\nbroadened by inter-vacancy hybridisation into a comb of satellite resonances at\nfinite energies. Our results establish point defects as a crucial source of\nelastic scattering that leads to nontrivial modifications in the electronic\nstructure of Weyl semimetals.",
        "positive": "Van der Waals Heterostructure Magnetic Josephson Junction: When two superconductors are connected across a ferromagnet, the spin\nconfiguration of the transferred Cooper pairs can be modulated due to magnetic\nexchange interaction. The resulting supercurrent can reverse its sign across\nthe Josephson junction (JJ) [1-4]. Here we demonstrate Josephson phase\nmodulation in van der Waals heterostructures when Cooper pairs from\nsuperconducting NbSe$_2$ tunnel through atomically thin magnetic insulator (MI)\nCr$_2$Ge$_2$Te$_6$. Employing a superconducting quantum interference device\nbased on MI JJs, we probe a doubly degenerate non-trivial JJ phase ($\\phi$)\noriginating from the magnetic barrier. This $\\phi$-phase JJ is formed by\nmomentum conserving tunneling of Ising Cooper pairs [5] across magnetic domains\nin the Cr$_2$Ge$_2$Te$_6$ barrier. The doubly degenerate ground states in MI\nJJs provide a two-level quantum system that can be utilized as a new\ndisipationless component for superconducting quantum devices, including phase\nbatteries [6], memories [7,8], and quantum Ratchets [9,10]."
    },
    {
        "anchor": "Antiferromagnetic Dirac Semimetals in Two Dimensions: The search for symmetry-protected 2D Dirac semimetals analogous to graphene\nis important both for fundamental and practical interest. The 2D Dirac cones\nare protected by crystalline symmetries and magnetic ordering may destroy their\nrobustness. Here we propose a general framework to classify stable 2D Dirac\nsemimetals in spin-orbit coupled systems having the combined time-reversal and\ninversion symmetries, and show the existence of the stable Dirac points in 2D\nantiferromagnetic semimetals. Compared to 3D Dirac semimetals which fall into\ntwo distinct classes, Dirac semimetals in 2D with combined time-reversal and\ninversion symmetries belongs to single class which is closely related to the\nnonsymmorphic space group symmetries. We further provide a concrete model in\nantiferromagnetic semimetals which supports symmetry-protected 2D Dirac points.\nThe symmetry breaking in such systems leads to 2D chiral topological states\nsuch as quantum anomalous Hall insulator and chiral topological superconductor\nphases.",
        "positive": "Nonadiabatic particle and energy pump at strong system-reservoir\n  coupling: We study the dynamics of electron and energy currents in a nonadiabatic pump.\nThe pump is a quantum dot nanojunction with time-varying gate potential and\ntunnel couplings to the leads. The leads are unbiased and maintained at the\nsame temperature and chemical potential. We find that synchronized variations\nof the gate and tunnel couplings can pump electrons and energy from the left to\nthe right lead. Inspired by quantum heat engines, we devise a four-stroke\noperating protocol that can optimally pump energy and hence, we investigate\nenergy transfer and the coefficient of performance of the device. We compare\nour device to a two-stroke pump and find that the latter's lower performance is\ndue to the bi-directional flow of energy currents resulting in low net energy\ncurrents. The performance of our four-stroke pump can be improved, up to a\npoint, by increasing the net energy carried by the pumped electrons through\nenergy charging via the gate potential. This is achieved by increasing the\ndurations of energy charging and discharging strokes in the pump's protocol.\nHowever, despite the large energy output for long charging and discharging\nstrokes, the energy required to maintain the strokes become large too resulting\nin a stagnant pump performance. Our pump operates effectively only in the\nstrong lead coupling regime and becomes a dud in the weak coupling regime due\nto the net output energy flowing in the reverse direction. We use\nnonequilibirum Green's functions techniques to calculate the currents and\ncapture the effects of strong lead-channel coupling exactly while\nsimultaneously incorporating three time-varying parameters. Results from our\nwork could aid in the design of high-performance quantum pumps."
    },
    {
        "anchor": "DIII Topological Superconductivity with Emergent Time-Reversal Symmetry: We find a new class of topological superconductors which possess an emergent\ntime-reversal symmetry that is present only after projecting to an effective\nlow-dimensional model. We show that a topological phase in symmetry class DIII\ncan be realized in a noninteracting system coupled to an $s$-wave\nsuperconductor only if the physical time-reversal symmetry of the system is\nbroken, and we provide three general criteria that must be satisfied in order\nto have such a phase. We also provide an explicit model which realizes the\nclass DIII topological superconductor in 1D. We show that, just as in\ntime-reversal invariant topological superconductors, the topological phase is\ncharacterized by a Kramers pair of Majorana fermions that are protected by the\nemergent time-reversal symmetry.",
        "positive": "On Ultrafast Spin Dynamics: Spin Dependent Fast Response of Hot\n  Electrons, of Band--Structure: Different energy shifts for majority and minority electrons occur. Thus, for\nexample in case of (laser) excited ferromagnetic metals majority and minority\nelectrons may respond differently in time during closing the exchange\nsplitting. Spin flip transitions of the hot electrons due to electron\ninteractions cause quasi hybridization of the spin split states. This is also\nthe case in itinerant ferromagnetic metals due to hopping between sites having\nmagnetic moments pointing in direction of the magnetization (+) and opposite\ndirection (-) and with energy levels $\\varepsilon^+_{i\\sigma}$ and\n$\\varepsilon^-_{i\\sigma}$. For energetic reasons the molecular field acts\nasymmetrically on the spins of the electrons and on spin flip transitions and\nthus causes different lifetimes of minority and majority electrons and spin\ndependent electron energy shifts. Quite general minority hot electrons in spin\nsplit states may respond faster than majority electrons at non--equilibrium.\nThe molecular field acting on the spins delays spin flip transitions $\\uparrow\n\\rightarrow \\downarrow$ and thus a response of the hot majority electrons and\ntheir energy levels. The closing of the exchange splitting in the electron\nspectrum of ferromagnetic transition and rare--earth metals, ferromagnetic\nsemiconductors, spin split quantum well states in thin ferromagnetic films,\netc. will reflect this. The time and spin dependent energy shifts of electrons\nat non--equilibrium may cause interesting behavior, in particular of magnetic\ntunnel junctions, spin currents etc.. In ferromagnets the moment reversal\nlifetime of (local) magnetic moments parallel to the global magnetization is\nlarger than of moments pointing in opposite direction."
    },
    {
        "anchor": "Electron Transfer on Impurity doped Graphene Nanoribbon: Electronic transport properties in armchair shaped edges graphene nanoribbons\n(AGNRs) doped various impurities have been simulated by the non-equilibrium\nGreen's function approach combined with the first principle calculation based\non the density functional theory. We have observed that impurity levels appear\nin electronic struc-tures, and that the quantization of transmission function\nis moderated for doped AGNRs. The I-V characteristic can be computed from the\ntransmission function. Our simulation results show that AGNRs doped impurities\nhave higher conductance than the non-doped one.",
        "positive": "Stochastic model for quantum spin dynamics in magnetic nanostructures: We develop a numerical model that reproduces the thermal equilibrium and the\nspin transfer mechanisms in magnetic nanomaterials. We analyze the coherent\ntwo-particle spin exchange interaction and the electron-electron collisions.\nOur study is based on a quantum atomistic approach and the particle dynamics is\nperformed by using a Monte Carlo technique. The coherent quantum evolution of\nthe atoms is interrupted by instantaneous collisions with itinerant electrons.\nThe collision processes are associated to the quantum collapse of the local\natomic wave function. We show that particle-particle interactions beyond the\nmolecular field approximation can be included in this framework. Our model is\nable to reproduce the thermal equilibrium and strongly out-of-equilibrium\nphenomena such as the ultrafast dynamics of the magnetization in nanomatrials."
    },
    {
        "anchor": "Topological transport of vorticity on curved magnetic membranes: In this work, we study the transport of vorticity on curved dynamical\ntwo-dimensional magnetic membranes. We find that topological transport can be\ncontrolled by geometrically reducing symmetries, which enables processes that\nare not present in flat magnetic systems. To this end, we construct a vorticity\n3-current which obeys a continuity equation. This continuity equation is immune\nto local fluctuations of the magnetic texture as well as spatiotemporal\nfluctuations of the membrane. We show how electric current can manipulate\nvortex transport in geometrically nontrivial magnetic systems. As an\nillustrative example, we propose a minimal setup that realizes an\nexperimentally feasible energy storage device.",
        "positive": "Inversion-symmetry protected chiral hinge states in stacks of doped\n  quantum Hall layers: We prove the existence of higher-order topological insulators with protected\nchiral hinge modes in quasi-two-dimensional systems made out of coupled layers\nstacked in an inversion-symmetric manner. In particular, we show that an\nexternal magnetic field drives a stack of alternating p- and n-doped buckled\nhoneycomb layers into a higher-order topological phase, characterized by a\nnon-trivial three-dimensional ${\\mathbb Z}_2$ invariant. We identify silicene\nmultilayers as a potential material platform for the experimental detection of\nthis novel topological insulating phase."
    },
    {
        "anchor": "Stability of trions in coupled quantum wells modelled by two-dimensional\n  bilayers: We report variational and diffusion quantum Monte Carlo calculations of the\nbinding energies of indirect trions and biexcitons in ideal two-dimensional\nbilayer systems within the effective-mass approximation, and with a Coulomb\n$1/r$ interaction between charge carriers. The critical layer separation at\nwhich trions become unbound has been studied for various electron-hole mass\nratios, and found to be over an order of magnitude larger than the critical\nlayer separation for biexcitons.",
        "positive": "Measurement of High Density Electrons Above a Helium Film on an\n  Amorphous Metal Substrate: We have measured two-dimensional electron systems bound to a thin helium film\nsupported by a metallic substrate. We report on our measurement of electron\ndensity obtained via a Kelvin probe technique. The underlying metallic\nsubstrate is an amorphous metallic alloy (TaWSi), which can support large\nuniform densities due to its low surface roughness and homogeneous work\nfunction. We find that this substrate is able to support high enough densities\nthat the electrons are expected to be Fermi-degenerate."
    },
    {
        "anchor": "Effects of Temperature Fluctuations on Charge Noise in Quantum Dot\n  Qubits: Silicon quantum dot qubits show great promise but suffer from charge noise\nwith a 1/f^\\alpha spectrum, where f is frequency and \\alpha \\lesssim 1. It has\nrecently been proposed that 1/f^\\alpha noise spectra can emerge from a few\nthermally activated two-level fluctuators in the presence of sub-bath\ntemperature fluctuations associated with a two-dimensional electron gas\n(2DEG)~\\cite{Ahn2021}. We investigate this proposal by doing Monte Carlo\nsimulations of a single Ising spin in a bath with a fluctuating temperature. We\nfind that to obtain noise with a $1/f^\\alpha$ spectrum with $alpha \\lesssim 1\ndown to low frequencies, the duration of temperature fluctuations must be\ncomparable to the inverse of the lowest frequency at which the noise is\nmeasured. This result is consistent with an analytic calculation in which the\nfluctuator is a two-state system with dynamics governed by time-dependent\nswitching rates. In this case we find that the noise spectrum follows a\nLorentzian at frequencies lower than the inverse of the average duration of the\nlowest switching rate. We then estimate relaxation times of thermal\nfluctuations by considering thermal diffusion in an electron gas in a confined\ngeometry. We conclude that temperature fluctuations in a 2DEG sub-bath would\nrequire an unphysically long duration to be consistent with experimental\nmeasurements of 1/f-like charge noise in quantum dots at frequencies extending\nwell below 1 Hz.",
        "positive": "Electrical Control of Plasmon Resonance with Graphene: Surface plasmon, with its unique capability to concentrate light into\nsub-wavelength volume, has enabled great advances in photon science, ranging\nfrom nano-antenna and single-molecule Raman scattering to plasmonic waveguide\nand metamaterials. In many applications it is desirable to control the surface\nplasmon resonance in situ with electric field. Graphene, with its unique\ntunable optical properties, provides an ideal material to integrate with\nnanometallic structures for realizing such control. Here we demonstrate\neffective modulation of the plasmon resonance in a model system composed of\nhybrid graphene-gold nanorod structure. Upon electrical gating the strong\noptical transitions in graphene can be switched on and off, which leads to\nsignificant modulation of both the resonance frequency and quality factor of\nplasmon resonance in gold nanorods. Hybrid graphene-nanometallic structures, as\nexemplified by this combination of graphene and gold nanorod, provide a general\nand powerful way for electrical control of plasmon resonances. It holds promise\nfor novel active optical devices and plasmonic circuits at the deep\nsubwavelength scale."
    },
    {
        "anchor": "Thickness dependent interlayer transport in vertical MoS2 Josephson\n  junctions: We report on observations of thickness dependent Josephson coupling and\nmultiple Andreev reflections (MAR) in vertically stacked molybdenum disulfide\n(MoS2) - molybdenum rhenium (MoRe) Josephson junctions. MoRe, a chemically\ninert superconductor, allows for oxide free fabrication of high transparency\nvertical MoS2 devices. Single and bilayer MoS2 junctions display relatively\nlarge critical currents (up to 2.5 uA) and the appearance of sub-gap structure\ngiven by MAR. In three and four layer thick devices we observe orders of\nmagnitude lower critical currents (sub-nA) and reduced quasiparticle gaps due\nto proximitized MoS2 layers in contact with MoRe. We anticipate that this\ndevice architecture could be easily extended to other 2D materials.",
        "positive": "Steady Bell state generation via magnon-photon coupling: We show that parity-time ($\\mathcal{PT}$) symmetry can be spontaneously\nbroken in the recently reported energy level attraction of magnons and cavity\nphotons. In the $\\mathcal{PT}$-broken phase, magnon and photon form a\nhigh-fidelity Bell state with maximum entanglement. This entanglement is steady\nand robust against the perturbation of environment, in contrast to the general\nwisdom that expects instability of the hybridized state when the symmetry is\nbroken. This anomaly is further understood by the compete of non-Hermitian\nevolution and particle number conservation of the hybridized system. As a\ncomparison, neither $\\mathcal{PT}$-symmetry broken nor steady magnon-photon\nentanglement is observed inside the normal level repulsion case. Our results\nmay open a novel window to utilize magnon-photon entanglement as a resource for\nquantum technologies."
    },
    {
        "anchor": "Spatially confined Bloch oscillations in semiconductor superlattices: In a semiconductor superlattice with long scattering times, damping of Bloch\noscillations due to scattering is so small that convective nonlinearities may\ncompensate it and Bloch oscillations persist even in the hydrodynamic regime.\nIn this case, numerical solutions show that there are stable Bloch oscillations\nconfined to a region near the collector with inhomogeneous field, charge,\ncurrent density and energy density profiles. These Bloch oscillations disappear\nwhen damping due to inelastic collisions becomes sufficiently strong.",
        "positive": "Contribution of Berry Curvature to Thermoelectric Effects: Within the semiclassical Boltzmann transport theory, the formula for Seebeck\ncoefficient $S$ is derived for an isotropic two-dimensional electron gas (2DEG)\nsystem that exhibits anomalous Hall effect (AHE) and anomalous Nernst effect\n(ANE) originating from Berry curvature on their bands. Deviation of $S$ from\nthe value $S_0$ estimated neglecting Berry curvarture is computed for a special\ncase of 2DEG with Zeeman and Rashba terms. The result shows that, under certain\nconditions the contribution of Berry curvature to Seebeck effect could be\nnon-negligible. Further study is needed to clarify the effect of additional\ncontributions from mechanisms of AHE and ANE other than pure Berry curvature."
    },
    {
        "anchor": "Dark exciton-exciton annihilation in monolayer WSe$_2$: The exceptionally strong Coulomb interaction in semiconducting\ntransition-metal dichalcogenides (TMDs) gives rise to a rich exciton landscape\nconsisting of bright and dark exciton states. At elevated densities, excitons\ncan interact through exciton-exciton annihilation (EEA), an Auger-like\nrecombination process limiting the efficiency of optoelectronic applications.\nAlthough EEA is a well-known and particularly important process in atomically\nthin semiconductors determining exciton lifetimes and affecting transport at\nelevated densities, its microscopic origin has remained elusive. In this joint\ntheory-experiment study combining microscopic and material-specific theory with\ntime- and temperature-resolved photoluminescence measurements, we demonstrate\nthe key role of dark intervalley states that are found to dominate the EEA rate\nin monolayer WSe$_2$. We reveal an intriguing, characteristic temperature\ndependence of Auger scattering in this class of materials with an excellent\nagreement between theory and experiment. Our study provides microscopic\ninsights into the efficiency of technologically relevant Auger scattering\nchannels within the remarkable exciton landscape of atomically thin\nsemiconductors.",
        "positive": "Particle Physics and Condensed Matter: The Saga Continues: Ideas from quantum field theory and topology have proved remarkably fertile\nin suggesting new phenomena in the quantum physics of condensed matter. Here\nI'll supply some broad, unifying context, both conceptual and historical, for\nthe abundance of results reported at the Nobel Symposium on \"New Forms of\nMatter, Topological Insulators and Superconductors\". Since they distill some\nmost basic ideas in their simplest forms, these concluding remarks might also\nserve, for non-specialists, as an introduction."
    },
    {
        "anchor": "Minimal graphene thickness for wear protection of diamond: We show by means of molecular dynamics simulations that graphene is an\nexcellent coating for diamond. The transformation of diamond to amorphous\ncarbon while sliding under pressure can be prevented by having at least two\ngraphene layers between the diamond slabs, making this combination of materials\nsuitable for new coatings and micro- and nanoelectromechanical devices. Grain\nboundaries, vacancies and adatoms on the diamond surface do not change this\npicture whereas reactive adsorbates between the graphene layers may have\ndetrimental effects. Our findings can be explained by the properties of layered\nmaterials where the weak interlayer bonding evolves to a strong interlayer\nrepulsion under pressure.",
        "positive": "Signatures of correlated defects in an ultra-clean Wigner crystal in the\n  extreme quantum limit: Low-disorder two-dimensional electron systems in the presence of a strong,\nperpendicular magnetic field terminate at very small Landau level filling\nfactors in a Wigner crystal (WC), where the electrons form an ordered array to\nminimize the Coulomb repulsion. The nature of this exotic, many-body, quantum\nphase is yet to be fully understood and experimentally revealed. Here we probe\none of WC's most fundamental parameters, namely the energy gap that determines\nits low-temperature conductivity, in record-mobility, ultra-high-purity,\ntwo-dimensional electrons confined to GaAs quantum wells. The WC domains in\nthese samples contain $\\simeq$ 1000 electrons. The measured gaps are a factor\nof three larger than previously reported for lower quality samples, and agree\nremarkably well with values predicted for the lowest-energy, intrinsic,\nhyper-corelated bubble defects in a WC made of flux-electron composite\nfermions, rather than bare electrons. The agreement is particularly noteworthy,\ngiven that the calculations are done for disorder-free composite fermion WCs,\nand there are no adjustable parameters. The results reflect the exceptionally\nhigh quality of the samples, and suggest that composite fermion WCs are indeed\nmore stable compared to their electron counterparts."
    },
    {
        "anchor": "Spilling of electronic states in Pb Quantum Wells: Energy-dependent apparent step heights of two-dimensional ultra-thin Pb\nislands grown on the Si(111)6$\\times$6Au surface have been investigated by a\ncombination of scanning tunneling microscopy, first-principles density\nfunctional theory and the particle in a box model calculations. The apparent\nstep height shows the thickness and energy dependent oscillatory behavior,\nwhich is directly related to the spilling of electron states into the vacuum\nexhibiting a quantum size effect. This has been unambiguously proven by\nextensive first-principles scanning tunneling microscopy and spectroscopy\nsimulations. An electronic contribution to the apparent step height is directly\ndetermined. At certain energies it reaches values as high as a half of the\natomic contribution. The applicability of the particle in a box model to the\nspilling of electron states is also discussed.",
        "positive": "Assessing bound states in a one-dimensional topological superconductor:\n  Majorana versus Tamm: Majorana bound states in topological superconductors have attracted intense\nresearch activity in view of applications in topological quantum computation.\nHowever, they are not the only example of topological bound states that can\noccur in such systems. We here study a model in which both Majorana and Tamm\nbound states compete. We show both numerically and analytically that,\nsurprisingly, the Tamm state remains partially localized even when the spectrum\nbecomes gapless. Despite this fact, we demonstrate that the Majorana\npolarization shows a clear transition between the two regimes."
    },
    {
        "anchor": "Polaronic signatures and spectral properties of graphene antidot\n  lattices: We explore the consequences of electron-phonon (e-ph) coupling in graphene\nantidot lattices (graphene nanomeshes), i.e., triangular superlattices of\ncircular holes (antidots) in a graphene sheet. They display a direct band gap\nwhose magnitude can be controlled via the antidot size and density. The\nrelevant coupling mechanism in these semiconducting counterparts of graphene is\nthe modulation of the nearest-neighbor electronic hopping integrals due to\nlattice distortions (Peierls-type e-ph coupling). We compute the full momentum\ndependence of the e-ph vertex functions for a number of representative antidot\nlattices. Based on the latter, we discuss the origins of the previously found\nlarge conduction-band quasiparticle spectral weight due to e-ph coupling. In\naddition, we study the nonzero-momentum quasiparticle properties with the aid\nof the self-consistent Born approximation, yielding results that can be\ncompared with future angle-resolved photoemission spectroscopy measurements.\nOur principal finding is a significant e-ph mass enhancement, an indication of\npolaronic behavior. This can be ascribed to the peculiar momentum dependence of\nthe e-ph interaction in these narrow-band systems, which favors small phonon\nmomentum scattering. We also discuss implications of our study for recently\nfabricated large-period graphene antidot lattices.",
        "positive": "Coupling of Josephson Currents in Quantum Hall Bilayers: We study ring shaped (Corbino) devices made of bilayer two-dimensional\nelectron gases in the total filling factor one quantized Hall phase which is\nconsidered to be a coherent BCS-like state of interlayer excitons. Identical\nJosephson currents are observed at the two edges while only a negligible\nconductance between them is found. The maximum Josephson current observed at\neither edge can be controlled by passing a second interlayer Josephson current\nat the other edge. Due to the large electric resistance between the two edges,\nthe interaction between them can only be mediated by the neutral interlayer\nexcitonic groundstate."
    },
    {
        "anchor": "Manipulating the Tomonaga-Luttinger exponent by electric field\n  modulation: We establish a theoretical framework for artificial control of the power-law\nsingularities in Tomonaga-Luttinger liquid states. The exponent governing the\npower-law behaviors is found to increase significantly with an increase in the\namplitude of the periodic electric field modulation applied externally to the\nsystem. This field-induced shift in the exponent indicates the tunability of\nthe transport properties of quasi-one-dimensional electron systems.",
        "positive": "Estimation of \u03c0-\u03c0 Electronic Couplings from Current Measurements: The {\\pi}-{\\pi} interactions between organic molecules are among the most\nimportant parameters for optimizing the transport and optical properties of\norganic transistors, light-emitting diodes, and (bio-) molecular devices.\nDespite substantial theoretical progress, direct experimental measurement of\nthe {\\pi}-{\\pi} electronic coupling energy parameter t has remained an old\nchallenge due to molecular structural variability and the large number of\nparameters that affect the charge transport. Here, we propose a study of\n{\\pi}-{\\pi} interactions from electrochemical and current measurements on a\nlarge array of ferrocene-thiolated gold nanocrystals. We confirm the\ntheoretical prediction that t can be assessed from a statistical analysis of\ncurrent histograms. The extracted value of t ca. 35 meV is in the expected\nrange based on our density functional theory analysis. Furthermore, the t\ndistribution is not necessarily Gaussian and could be used as an ultrasensitive\ntechnique to assess intermolecular distance fluctuation at the subangstr\\\"om\nlevel. The present work establishes a direct bridge between quantum chemistry,\nelectrochemistry, organic electronics, and mesoscopic physics, all of which\nwere used to discuss results and perspectives in a quantitative manner."
    },
    {
        "anchor": "The distance upon contact: Determination from roughness profile: The point at which two random rough surfaces make contact takes place at the\ncontact of the highest asperities. The distance upon contact d_0 in the limit\nof zero load has crucial importance for determination of dispersive forces.\nUsing gold films as an example we demonstrate that for two parallel plates d_0\nis a function of the nominal size of the contact area L and give a simple\nexpression for d_0(L) via the surface roughness characteristics. In the case of\na sphere of fixed radius R and a plate the scale dependence manifests itself as\nan additional uncertainty \\delta d(L) in the separation, where the scale L is\nrelated with the separation d via the effective area of interaction L^2\\sim\\pi\nRd. This uncertainty depends on the roughness of interacting bodies and\ndisappears in the limit L\\to \\infty.",
        "positive": "Negative differential resistances with back gate-controlled lowest\n  operation windows in graphene double barrier resonant tunneling diodes: We theoretically investigate negative differential resistance (NDR) of\nmassless and massive Dirac Fermions in double barrier resonant tunneling diodes\nbased on sufficiently short and wide graphene strips. The current-voltage\ncharacteristics calculated in a rotated pseudospin space show that, the NDR\nfeature only presents with appropriate structural parameters for the massless\ncase and the peak-to-valley current ratio can be enhanced exponentially by a\ntunable band gap. Remarkably, the lowest NDR operation window is nearly\nstructure-free and can be almost solely controlled by a back gate, which may\nhave potential applications in NDR devices with the operation window as a\ncrucial parameter."
    },
    {
        "anchor": "High-fidelity spin qubit shuttling via large spin-orbit interaction: Shuttling spins with high fidelity is a key requirement to scale up\nsemiconducting quantum computers, enabling qubit entanglement over large\ndistances and favoring the integration of control electronics on-chip. To\ndecouple the spin from the unavoidable charge noise, state-of-the-art spin\nshuttlers try to minimize the inhomogeneity of the Zeeman field. However, this\ndecoupling is challenging in otherwise promising quantum computing platforms\nsuch as hole spin qubits in silicon and germanium, characterized by a large\nspin-orbit interaction and electrically-tunable qubit frequency. In this work,\nwe show that, surprisingly, the large inhomogeneity of the Zeeman field\nstabilizes the coherence of a moving spin state, thus enabling high-fidelity\nshuttling also in these systems. We relate this enhancement in fidelity to the\ndeterministic dynamics of the spin which filters out the dominant low-frequency\ncontributions of the charge noise. By simulating several different scenarios\nand noise sources, we show that this is a robust phenomenon generally occurring\nat large field inhomogeneity. By appropriately adjusting the motion of the\nquantum dot, we also design realistic protocols enabling faster and more\ncoherent spin shuttling. Our findings are generally applicable to a wide range\nof setups and could pave the way toward large-scale quantum processors.",
        "positive": "Self-Induced Valley Bosonic Stimulation of Exciton-Polaritons in a\n  Monolayer Semiconductor: The newly discovered valley degree of freedom in atomically thin\ntwo-dimensional transition metal dichalcogenides (TMD) offers a promising\nplatform to explore rich nonlinear physics, such as spinor Bose-Einstein\ncondensate (BEC) and novel valleytronics applications. However, the critical\nnonlinear effect, such as valley polariton bosonic stimulation, has long\nremained an unresolved challenge due to the generation of limited polariton\nground state densities necessary to induce the stimulated scattering of\npolaritons in specific valleys. Here, we report the self-induced valley bosonic\nstimulation of exciton-polaritons via spin-valley locking in a WS2 monolayer\nmicrocavity. This is achieved by the resonant injection of valley polaritons at\nspecific energy and wavevector, which allows spin-polarized polaritons to\nefficiently populate their ground state and induce a valley-dependent bosonic\nstimulation. As a result, we observe the nonlinear self-amplification of\npolariton emission from the valley-dependent ground state. Our finding paves\nthe way for the investigation of spin ordering and phase transitions in TMD\npolariton BEC, offering a promising route for the realization of polariton spin\nlattices in moir\\'e polariton systems and spin-lasers."
    },
    {
        "anchor": "Finite Size Effects of Thermal Conductivity for One-Dimensional\n  Mesoscopic Systems: The finite size effects of the thermal conductivity $\\kappa$ have been\nstudied in the phonon space. It is found that only a few phonon modes are\nselected to take part in the thermal transport when the size $L$ of the system\nis decreased. The amount of the selected phonon modes is proportional to the\n$L$. In this way, $\\kappa$ decreases with the decreasing of $L$. Such mechanism\nfor the size effect of $\\kappa$ found in this work is beyond the\nPhonon-Boundary scattering. The exponent $\\alpha$ of the power law $\\kappa \\sim\nL^{\\alpha}$ has been fitted, showing that the exponent is not universal.",
        "positive": "Field-Free Synthetic-Ferromagnet Spin Torque Oscillator: We study the magnetization dynamics of spin valve structures with a free\ncomposite synthetic ferromagnet (SyF) that consists of two ferromagnetic layers\ncoupled through a normal metal spacer. A ferromagnetically coupled SyF can be\nexcited into dynamical precessional states by an applied current without\nexternal magnetic fields. We analytically determine the stability of these\nstates in the space spanned by the current density and SyF interlayer exchange\ncoupling. Numerical simulations confirm our analytical results."
    },
    {
        "anchor": "Josephson junction based thermometer and its application in bolometry: We propose a new type of a transition edge sensor based on an\nAl/AlOx/Ti/AlOx/Al superconductor - insulator - superconductor - insulator -\nsuperconductor (SIS'IS) structure. It exhibits sharp dependence of zero bias\nresistance on temperature of the titanium absorber in the vicinity of its\nsuperconducting critical temperature. We demonstrate temperature sensitivity of\nthe device to be $2\\ \\mu \\text{K}/\\sqrt{\\text{Hz}}$. Noise Equivalent Power\n(NEP) of the device, limited by the amplifier noise, is estimated to be\n$4\\times 10^{-17}\\ {\\rm W}/ \\sqrt{\\rm Hz}$ at 313 mK. The tunnel junctions\nbetween superconducting leads should help to overcome the size limitation\nimposed by proximity effect in conventional transition edge sensors, without\nsacrificing the sensitivity. Besides that, the input resistance of the device\ncan be tuned in a wide range.",
        "positive": "Low-temperature linear transport of two-dimensional massive Dirac\n  fermions in silicene: residual conductivity and spin/valley Hall effects: Considering finite-temperature screened electron-impurity scattering, we\npresent a kinetic equation approach to investigate transport properties of\ntwo-dimensional massive fermions in silicene. We find that the longitudinal\nconductivity is always nonvanishing when chemical potential lies within the\nenergy gap. This residual conductivity arises from interband correlation and\nstrongly depends on strength of electron-impurity scattering. We also clarify\nthat the electron-impurity interaction makes substantial contributions to the\nspin- and valley-Hall conductivities, which, however, are almost independent of\nimpurity density. The dependencies of longitudinal conductivity as well as of\nspin- and valley-Hall conductivities on chemical potential, on temperature, and\non gap energy are analyzed."
    },
    {
        "anchor": "Phase Transitions and Generalized Biorthogonal Polarization in\n  Non-Hermitian Systems: Non-Hermitian (NH) Hamiltonians can be used to describe dissipative systems,\nand are currently intensively studied in the context of topology. A salient\ndifference between Hermitian and NH models is the breakdown of the conventional\nbulk-boundary correspondence invalidating the use of topological invariants\ncomputed from the Bloch bands to characterize boundary modes in generic NH\nsystems. One way to overcome this difficulty is to use the framework of\nbiorthogonal quantum mechanics to define a biorthogonal polarization, which\nfunctions as a real-space invariant signaling the presence of boundary states.\nHere, we generalize the concept of the biorthogonal polarization beyond the\nprevious results to systems with any number of boundary modes, and show that it\nis invariant under basis transformations as well as local unitary\ntransformations. Additionally, we propose a generalization of a\nperviously-developed method with which to find all the bulk states of system\nwith open boundaries to NH models. Using the exact solutions in combination\nwith variational states, we elucidate genuinely NH aspects of the interplay\nbetween bulk and boundary at the phase transitions.",
        "positive": "L lines, C points and Chern numbers: understanding band structure\n  topology using polarization fields: Topology has appeared in different physical contexts. The most prominent\napplication is topologically protected edge transport in condensed matter\nphysics. The Chern number, the topological invariant of gapped Bloch\nHamiltonians, is an important quantity in this field. Another example of\ntopology, in polarization physics, are polarization singularities, called L\nlines and C points. By establishing a connection between these two theories, we\ndevelop a novel technique to visualize and potentially measure the Chern\nnumber: it can be expressed either as the winding of the polarization azimuth\nalong L lines in reciprocal space, or in terms of the handedness and the index\nof the C points. For mechanical systems, this is directly connected to the\nvisible motion patterns."
    },
    {
        "anchor": "Josephson effect in silicene-based SNS Josephson junction: Andreev\n  reflection and free energy: We investigate the Josephson effcet in superconductor-normal-superconductor\njunction (SNS) base on the doped unbiased silicene under the perpendicular\nelectric field and off-resonance circularly polarized light. The Andreev\nreflection (including the retroreflection and specular one) during the subgap\ntransport, the free energy, and the reversal of the Josephson effect as well as\nthe emergence of $\\phi_{0}$-junction are exploited. The Andreev reflection is\ncomplete in the NS interface even for the clean interface and without the Fermi\nwave vector mismatch, which is opposite to the case of\nferromagnet-superconductor interface. The important role played by the\ndynamical polarization of the degrees of freedom to the $0-\\pi$ transition and\nthe generation of $\\phi_{0}$-junction are mentioned in this paper. The\nscattering by the charged impurity in the substrate affects the transport\nproperties in the bulk as well as the valley relaxation, which can be taken\ninto consider by the macroscopic wave function. In short junction limit, the\napproximated results about the Andreev level and free energy are also\ndiscussed. Beside the low-energy limit of the tight-binding model, the\nfinite-size effect need to be taken into account as long as the spacing model\nis much larger than the superconducting gap.",
        "positive": "Signatures of long-range spin-spin interactions in an (In,Ga)As quantum\n  dot ensemble: We present an investigation of the electron spin dynamics in an ensemble of\nsingly-charged quantum dots subject to an external magnetic field and laser\npumping with circularly polarized light. The spectral laser width is tailored\nsuch that different groups of quantum dots are coherently pumped. Surprisingly,\nthe dephasing time $T^*$ of the electron spin polarization depends only weakly\non the laser spectral width. These findings can be consistently explained by a\ncluster theory of coupled quantum dots with a long range electronic spin-spin\ninteraction. We present a numerical simulation of the spin dynamics based on\nthe central spin model that includes a quantum mechanical description of the\nlaser pulses as well as a time-independent Heisenberg interaction between each\npair of electron spins. We discuss the individual dephasing contributions\nstemming from the Overhauser field, the distribution of the electron\n$g$-factors and the electronic spin-spin interaction as well as the spectral\nwidth of the laser pulse. This analysis reveals the counterbalancing effect of\nthe total dephasing time when increasing the spectral laser width. On one hand,\nthe deviations of the electron $g$-factors increase. On the other hand, an\nincreasing number of coherently pumped electron spins synchronize due to the\nspin-spin interaction. We find an excellent agreement between the experimental\ndata and the dephasing time in the simulation using an exponential distribution\nof Heisenberg couplings with a mean value $\\overline{J}\\approx\n0.26\\,\\mathrm{\\mu eV}$."
    },
    {
        "anchor": "Dependence of nonlocal Gilbert damping on the ferromagnetic layer type\n  in FM/Cu/Pt heterostructures: We have measured the size effect in nonlocal Gilbert relaxation rate in\nFM(t$_{FM}$) / Cu (5nm) [/ Pt (2nm)] / Al(2nm) heterostructures, FM = \\{\nNi$_{81}$Fe$_{19}$, Co$_{60}$Fe$_{20}$B$_{20}$, pure Co\\}. Common behavior is\nobserved for three FM layers, where the additional relaxation obeys both a\nstrict inverse power law dependence $\\Delta G =K \\:t^{n}$,\n$n=-\\textrm{1.04}\\pm\\textrm{0.06}$ and a similar magnitude\n$K=\\textrm{224}\\pm\\textrm{40 Mhz}\\cdot\\textrm{nm}$. As the tested FM layers\nspan an order of magnitude in spin diffusion length $\\lambda_{SDL}$, the\nresults are in support of spin diffusion, rather than nonlocal resistivity, as\nthe origin of the effect.",
        "positive": "Near-field refrigeration and tunable heat exchange through four-wave\n  mixing: We modify and extend a recently proposed four-wave mixing scheme [Opt.\nExpress 25 (19),23164 (2017)] for achieving near-field thermal upconversion and\nenergy transfer, to demonstrate efficient thermal refrigeration at low\nintensities $\\sim 10^{-9}$W/m$^2$ over a wide range of gap sizes (from tens to\nhundreds of nanometers) and operational temperatures (from tens to hundreds of\nKelvins). We further exploit the scheme to achieve magnitude and directional\ntunability of near-field heat exchange between bodies held at different\ntemperatures."
    },
    {
        "anchor": "Spin Polarization of the 12/5 Fractional Quantum Hall Effect: We have carried out tilt magnetic field (B) studies of the \\nu=12/5\nfractional quantum Hall state in an ultra-high quality GaAs quantum well\nspecimen. Its diagonal magneto-resistance Rxx shows a non-monotonic dependence\non tilt angle (\\theta). It first increases sharply with increasing \\theta,\nreaches a maximal value of ~ 70 ohms at \\theta ~ 14^o, and then decreases at\nhigher tilt angles. Correlated with this dependence of Rxx on \\theta, the 12/5\nactivation energy (\\Delta_{12/5}) also shows a non-monotonic tilt dependence.\n\\Delta_{12/5} first decreases with increasing \\theta. Around \\theta = 14^{o},\n\\Delta_{12/5} disappears as Rxx becomes non-activated. With further increasing\ntilt angles, \\Delta_{12/5} reemerges and increases with \\theta. This tilt B\ndependence at \\nu=12/5 is strikingly different from that of the well-documented\n5/2 state and calls for more investigations on the nature of its ground state.",
        "positive": "Tunneling conduction in graphene/(poly)vinyl alcohol composites: Graphene/(Poly)vinyl alcohol (PVA) composite film with thickness $60 \\mu m$\nwere synthesized by solidification of a PVA solution comprising of dispersed\ngraphene nanosheets. The close proximity of the graphene sheets enables the\nfluctuation induced tunneling of electrons to occur from one sheet to another.\nThe dielectric data show that the present system can be simulated to a parallel\nresistance-capacitor network. The high frequency exponent of the frequency\nvariation of the ac conductivity indicates that the charge carriers move in a\ntwo-dimensional space. The sample preparation technique will be helpful for\nsynthesizing flexible conductors."
    },
    {
        "anchor": "Bragg Reflection Waveguide: Anti-Mirror Reflection and Light Slowdown: The effect of the light group velocity reduction in dielectric Bragg\nreflection waveguide structures (SiO$_2$/TiO$_2$) in the vicinity of the cutoff\nfrequency is studied experimentally. The effect of anti-mirror reflection,\nspecific for the Bragg reflection waveguides, is described and employed for\ndetection of \"slow light\". The experiments were performed with the use of the\nTi:sapphire laser pulses ~ 100 fs in length. The group index $n_g \\sim$ 30 with\na fractional pulse delay (normalized to the pulse width) of $\\sim$ 10 is\ndemonstrated. The problems and prospects of implementation of the slow-light\ndevices based on the Bragg reflection waveguide structures are discussed.",
        "positive": "Josephson-phase qubit without tunneling: We show that a complete set of one-bit gates can be realized by coupling the\ntwo logical states of a phase qubit to a third level (at higher energy) using\nmicrowave pulses. Thus, one can achieve coherent control without invoking any\ntunneling between the qubit levels. We propose two implementations, using\nrf-SQUIDs and d-wave Josephson junctions."
    },
    {
        "anchor": "The topological Anderson insulator phase in the Kane-Mele model: It has been proposed that adding disorder to a topologically trivial mercury\ntelluride/cadmium telluride (HgTe/CdTe) quantum well can induce a transition to\na topologically nontrivial state. The resulting state was termed topological\nAnderson insulator and was found in computer simulations of the\nBernevig-Hughes-Zhang model. Here, we show that the topological Anderson\ninsulator is a more universal phenomenon and also appears in the Kane-Mele\nmodel of topological insulators on a honeycomb lattice. We numerically\ninvestigate the interplay of the relevant parameters, and establish the\nparameter range in which the topological Anderson insulator exists. A staggered\nsublattice potential turns out to be a necessary condition for the transition\nto the topological Anderson insulator. For weak enough disorder, a calculation\nbased on the lowest-order Born approximation reproduces quantitatively the\nnumerical data. Our results thus considerably increase the number of candidate\nmaterials for the topological Anderson insulator phase.",
        "positive": "Accurate formation energies of charged defects in solids: a systematic\n  approach: Defects on surfaces of semiconductors have a strong effect on their\nreactivity and catalytic properties. The concentration of different charge\nstates of defects is determined by their formation energies. First-principles\ncalculations are an important tool for computing defect formation energies and\nfor studying the microscopic environment of the defect. The main problem\nassociated with the widely used supercell method in these calculations is the\nerror in the electrostatic energy, which is especially pronounced in\ncalculations that involve surface slabs and 2D materials. We present an\ninternally consistent approach for calculating defect formation energies in\ninhomogeneous and anisotropic dielectric environments, and demonstrate its\napplicability to the cases of the positively charged Cl vacancy on the NaCl\n(100) surface and the negatively charged S vacancy in monolayer MoS2."
    },
    {
        "anchor": "Single-atom anchored novel two-dimensional MoSi2N4 monolayers for\n  efficient electroreduction of CO2 to formic acid and methane: Efficient and selective CO2 electroreduction into value-added chemicals and\nfuels emerged as a significant approach for CO2 conversion, however, it relies\non catalysts with controllable product selectivity and reaction paths. In this\nwork, by means of first-principles calculations, we identify five catalysts\n(TM@MoSi2N4, TM = Sc, Ti, Fe, Co and Ni) comprising transition-metal atoms\nanchored on a MoSi2N4 monolayer, whose catalytic performance can be controlled\nby adjusting the d-band center and occupation of supported metal atoms. During\nCO2 reduction, the single metal atoms function as the active sites activates\nthe MoSi2N4 inert basal-plane, and as-designed electrocatalysts exhibit\nexcellent activity in CO2 reduction. Interestingly, HCOOH is the preferred\nproduct of CO2 reduction on the Co@MoSi2N4 catalyst with a rate-determining\nbarrier of 0.89 eV, while the other four catalysts prefer to reduce CO2 to CH4\nwith a rate-determining barrier of 0.81-1.24 eV. Moreover, MoSi2N4 is an\nextremely-air-stable material, which will facilitate its application in various\nenvironments. Our findings provide a promising candidate with high activity,\ncatalysts for renewable energy technologies, and selectivity for experimental\nwork.",
        "positive": "Orbital Dynamics in Centrosymmetric Systems: Orbital dynamics in time-reversal-symmetric centrosymmetric systems is\nexamined theoretically. Contrary to common belief, we demonstrate that many\naspects of orbital dynamics are qualitatively different from spin dynamics\nbecause the algebraic properties of the orbital and spin angular momentum\noperators are different. This difference generates interesting orbital\nresponses, which do not have spin counterparts. For instance, the orbital\nangular momentum expectation values may oscillate even without breaking neither\nthe time-reversal nor the inversion symmetry. Our quantum Boltzmann approach\nreproduces the previous result on the orbital Hall effect and reveals\nadditional orbital dynamics phenomena, whose detection schemes are discussed\nbriefly. Our work will be useful for the experimental differentiation of the\norbital dynamics from the spin dynamics."
    },
    {
        "anchor": "Charge Trapping Dynamics in PbS Colloidal Quantum Dot Photovoltaic\n  Devices: The efficiency of solution-processed colloidal quantum dot (QD) based solar\ncells is limited by poor charge transport in the active layer of the device,\nwhich originates from multiple trapping sites provided by QD surface defects.\nWe apply a recently developed ultrafast electro-optical technique, pump-push\nphotocurrent spectroscopy, to elucidate the charge trapping dynamics in PbS\ncolloidal-QD photovoltaic devices at working conditions. We show that IR\nphoto-induced absorption of QD in the 0.2-0.5 eV region is partly associated\nwith immobile charges, which can be optically de-trapped in our experiment.\nUsing this absorption as a probe, we observe that the early trapping dynamics\nstrongly depend on the nature of the ligands used for QD passivation while it\ndepends only slightly on the nature of the electron-accepting layer. We find\nthat weakly bound states, with a photon-activation energy of 0.2 eV, are\npopulated instantaneously upon photoexcitation. This indicates that the\nphotogenerated states show an intrinsically bound-state character, arguably\nsimilar to charge-transfer states formation in organic photovoltaic materials.\nSequential population of deeper traps (activation energy 0.3-0.5 eV) is\nobserved on the ~0.1-10 ns time scales, indicating that most of carrier\ntrapping occurs only after substantial charge relaxation/transport. The\nreported study disentangles fundamentally different contributions to charge\ntrapping dynamics in the nanocrystal-based optoelectronic devices and can serve\nas a useful tool for QD solar cell development.",
        "positive": "Imaging of optically active defects with nanometer resolution: Point defects significantly influence the optical and electrical properties\nof solid-state materials due to their interactions with charge carriers, which\nreduce the band-to-band optical transition energy. There has been a demand for\ndeveloping direct optical imaging methods that would allow in-situ\ncharacterization of individual defects with nanometer resolution. Here, we\ndemonstrate the localization and quantitative counting of individual optically\nactive defects in monolayer hexagonal boron nitride using single molecule\nlocalization microscopy. By exploiting the blinking behavior of defect emitters\nto temporally isolate multiple emitters within one diffraction limited region,\nwe could resolve two defect emitters with a point-to-point distance down to ten\nnanometers. The results and conclusion presented in this work add unprecedented\ndimensions towards future applications of defects in quantum information\nprocessing and biological imaging."
    },
    {
        "anchor": "Enhancement of quantum dot peak-spacing fluctuations in the fractional q\n  uantum Hall regime: The fluctuations in the spacing of the tunneling resonances through a quantum\ndot have been studied in the quantum Hall regime. Using the fact that the\nground-state of the system is described very well by the Laughlin wavefunction,\nwe were able to determine accurately, via classical Monte Carlo calculations,\nthe amplitude and distribution of the peak-spacing fluctuations.\n  Our results clearly demonstrate a big enhancement of the fluctuations as the\nimportance of the electronic correlations increases, namely as the density\ndecreases and filling factor becomes smaller.\n  We also find that the distribution of the fluctuations approaches a Gaussian\nwith increasing density of random potentials.",
        "positive": "Topological Insulators on the Decorated Honeycomb Lattice: We show that the decorated honeycomb lattice supports a number of topological\ninsulating phases with a non-trivial Z_2 invariant and time-reversal symmetry\nprotected gapless edge modes. We investigate the stability of these phases with\nrespect to various symmetry breaking perturbations and demonstrate the\nconnection to the recently discovered exactly solvable S=1/2 chiral spin liquid\nmodel [Phys. Rev. Lett. 99, 247203 (2007)] with non-Abelian and Abelian\nexcitations on the same lattice. Our work highlights the relationship between\ntopological band insulators and topologically ordered spin systems, and points\nto promising avenues for enlarging the number of known examples of both."
    },
    {
        "anchor": "Giant transition-state enhancement of quasiparticle spin-Hall effect in\n  an exchange-spin-split superconductor detected by non-local magnon\n  spin-transport: Although recent experiments and theories have shown a variety of exotic\ntransport properties of non-equilibrium quasiparticles (QPs) in superconductor\n(SC)-based devices with either Zeeman or exchange spin-splitting, how QP\ninterplays with magnon spin currents remains elusive. Here, using non-local\nmagnon spin-transport devices where a singlet SC (Nb) on top of a ferrimagnetic\ninsulator (Y3Fe5O12) serves as a magnon spin detector, we demonstrate that the\nconversion efficiency of magnon spin to QP charge via inverse spin-Hall effect\n(iSHE) in such an exchange-spin-split SC can be greatly enhanced by up to 3\norders of magnitude compared with that in the normal state, particularly when\nits interface superconducting gap matches the magnon spin accumulation. Through\nsystematic measurements with varying the current density and SC thickness, we\nidentify that superconducting coherence peaks and exchange spin-splitting of\nthe QP density-of-states, yielding a larger spin excitation while retaining a\nmodest QP charge-imbalance relaxation, are responsible for the giant QP iSHE.\nThe latter exchange-field-modified QP relaxation is experimentally proved by\nspatially resolved measurements with varying the separation of electrical\ncontacts on the spin-split Nb.",
        "positive": "Nanobubble induced formation of quantum emitters in monolayer\n  semiconductors: The recent discovery of exciton quantum emitters in transition metal\ndichalcogenides (TMDCs) has triggered renewed interest of localized excitons in\nlow-dimensional systems. Open questions remain about the microscopic origin\npreviously attributed to dopants and/or defects as well as strain potentials.\nHere we show that the quantum emitters can be deliberately induced by\nnanobubble formation in WSe2 and BN/WSe2 heterostructures. Correlations of\natomic-force microscope and hyperspectral photoluminescence images reveal that\nthe origin of quantum emitters and trion disorder is extrinsic and related to\n10 nm tall nanobubbles and 70 nm tall wrinkles, respectively. We further\ndemonstrate that hot stamping results in the absence of 0D quantum emitters and\ntrion disorder. The demonstrated technique is useful for advances in nanolasers\nand deterministic formation of cavity-QED systems in monolayer materials."
    },
    {
        "anchor": "Nonadiabatic corrections to electric current in molecular junction due\n  to nuclear motion at the molecule-electrode interfaces: We present quantum electron transport theory that incorporates dynamical\neffects of motion of atoms on electrode-molecule interfaces in the calculations\nof the electric current. The theory is based on non-equilibrium Green's\nfunctions. We separate time scales in the Green's functions on fast relative\ntime and slow central time. The derivative with respect to the central time\nserves as a small parameter in the theory. We solve the real-time Kadanoff-Baym\nequations for molecular Green's functions using Wigner representation and keep\nterms up to the second order with respect to the central time derivatives.\nMolecular Green's functions and consequently the electric current are expressed\nas functions of molecular junction coordinates as well as velocities and\naccelerations of molecule-electrode interface nuclei. We apply the theory to\nmodel a molecular system and study the effects of non-adiabatic nuclear motion\non molecular junction conductivity.",
        "positive": "Direct determination of the electron-electron mean free path in\n  diffusive mesoscopic samples using shot noise: Using the 'drift-diffusion-Langevin' equation, we have recently shown that\nfinite-frequency shot noise in diffusive mesoscopic conductors is very\nsensitive to the ratio $\\gamma \\equiv L/\\lee$ between the sample length $L$ and\nthe electron-electron mean free path $\\lee$. In this work we present numerical\ncalculations of the noise at arbitrary value of $\\gamma$. If coupled with\naccurate noise measurements, the results presented here could serve as a new\nand independent way of determining $\\lee$ in a given sample."
    },
    {
        "anchor": "Topological Insulators, Topological Crystalline Insulators, Topological\n  Semimetals and Topological Kondo Insulators: In this Book Chapter (invited) we briefly review the basic concepts defining\ntopological insulators and focus on elaborating on the key experimental results\nthat revealed and established their symmetry protected (SPT) topological\nnature. We then present key experimental results that demonstrate magnetism,\nKondo insulation, mirror chirality or topological crystalline order and\nsuperconductivity in spin-orbit topological insulator settings and how these\nnew (bulk insulating) phases of matter arise through topological quantum phase\ntransitions from Bloch band insulators via topological or Dirac semimetals at\nthe critical point.",
        "positive": "Topological magnetoelectric pump in three dimensions: We study the topological pump for a lattice fermion model mainly in three\nspatial dimensions. We first calculate the U(1) current density for the Dirac\nmodel defined in continuous space-time to review the known results as well as\nto introduce some technical details convenient for the calculations of the\nlattice model. We next investigate the U(1) current density for a lattice\nfermion model, a variant of the Wilson-Dirac model. The model we introduce is\ndefined on a lattice in space but in continuous time, which is suited for the\nstudy of the topological pump. For such a model, we derive the conserved U(1)\ncurrent density and calculate it directly for the $1+1$ dimensional system as\nwell as $3+1$ dimensional system in the limit of the small lattice constant. We\nfind that the current includes a nontrivial lattice effect characterized by the\nChern number, and therefore, the pumped particle number is quantized by the\ntopological reason. Finally we study the topological temporal pump in $3+1$\ndimensions by numerical calculations. We discuss the relationship between the\nsecond Chern number and the first Chern number, the bulk-edge correspondence,\nand the generalized Streda formula which enables us to compute the second Chern\nnumber using the spectral asymmetry."
    },
    {
        "anchor": "Theory of the Spin Seebeck Effect: The spin Seebeck effect refers to the generation of a spin voltage caused by\na temperature gradient in a ferromagnet, which enables the thermal injection of\nspin currents from the ferromagnet into an attached nonmagnetic metal over a\nmacroscopic scale of several millimeters. The inverse spin Hall effect converts\nthe injected spin current into a transverse charge voltage, thereby producing\nelectromotive force as in the conventional charge Seebeck device. Recent\ntheoretical and experimental efforts have shown that the magnon and phonon\ndegrees of freedom play crucial roles in the spin Seebeck effect. In this\narticle, we present the theoretical basis for understanding the spin Seebeck\neffect and briefly discuss other thermal spin effects.",
        "positive": "Resonance electronic excitation energy transfer in the quantum dot\n  system: Microscopic theory of the nonradiative energy transfer in a system of III-V\nsemiconductor quantum dots is elaborated in our work. The energy transfer both\ndue to direct Coulomb and due to exchange interactions between two quantum dots\n(energy donor and acceptor) is considered. An analysis of energy transfer\nprocess is performed in the frame of the Kane model that provides the most\nadequate description of the real energy spectra and wave functions of III-V\nsemiconductors. The density-matrix method is applied, which enabled us to\nanalyze the energy transfer rate both in the weak-interaction approximation and\nin the strong-interaction approximation. For the first time the detailed\nanalytical calculations of the exchange energy transfer rate for the quantum\ndot system are performed. The analytical expressions for contributions to the\ntransfer rate are derived. The numerical calculations showed that at nearly\ncontact distances between two quantum dots the rate of the energy transfer due\nto the direct Coulomb interaction as well as by exchange interaction can reach\nthe saturation. At the small distances, these two contributions can be of the\nsame order and can have the same value in the saturation range. It is revealed\nthat the exchange interaction should be taken into consideration in qualitative\ndescribing the energy transfer at small distances between the quantum dot donor\nand the quantum dot acceptor."
    },
    {
        "anchor": "Resonant tunneling and quantum interference of a two-spin system in\n  silicon tunnel FETs: We investigated the resonant tunneling of a two-spin system through the\ndouble quantum dots in Al-N-implanted silicon tunnel FETs (TFETs) by\nelectrical-transport measurements and Landau-Zener-St\\\"{u}ckelberg-Majorana\ninterferometry with and without magnetic fields. Our experimental results\nrevealed the coexistence of spin-conserving and spin-flip tunneling channels in\nthe two-spin system in non-zero magnetic fields. Additionally, we obtained the\nspin-conserving/spin-flip tunneling rates of the two-spin system through the\ndouble quantum dots in the TFET. These findings will improve our understanding\nof the two-spin system in silicon TFET qubits and may facilitate the coherent\ncontrol of quantum states through all-electric manipulation.",
        "positive": "Tunable refrigerator for non-linear quantum electric circuits: The emerging quantum technological applications call for fast and accurate\ninitialization of the corresponding devices to low-entropy quantum states. To\nthis end, we theoretically study a recently demonstrated quantum-circuit\nrefrigerator in the case of non-linear quantum electric circuits such as\nsuperconducting qubits. The maximum refrigeration rate of transmon and flux\nqubits is observed to be roughly an order of magnitude higher than that of\nusual linear resonators, increasing flexibility in the design. We find that for\ntypical experimental parameters, the refrigerator is suitable for resetting\ndifferent qubit types to fidelities above 99.99% in a few or a few tens of\nnanoseconds depending on the scenario. Thus the refrigerator appears to be a\npromising tool for quantum technology and for detailed studies of open quantum\nsystems."
    },
    {
        "anchor": "Magneto-resistance quantum oscillations in a magnetic two-dimensional\n  electron gas: Magneto-transport measurements of Shubnikov-de Haas (SdH) oscillations have\nbeen performed on two-dimensional electron gases (2DEGs) confined in CdTe and\nCdMnTe quantum wells. The quantum oscillations in CdMnTe, where the 2DEG\ninteracts with magnetic Mn ions, can be described by incorporating the\nelectron-Mn exchange interaction into the traditional Lifshitz-Kosevich\nformalism. The modified spin splitting leads to characteristic beating pattern\nin the SdH oscillations, the study of which indicates the formation of Mn\nclusters resulting in direct anti-ferromagnetic Mn-Mn interaction. The Landau\nlevel broadening in this system shows a peculiar decrease with increasing\ntemperature, which could be related to statistical fluctuations of the Mn\nconcentration.",
        "positive": "Coherent Magneto-Optical Effects in Topological Insulators: Excitation\n  Near the Absorption Edge: We study coherent optics in topological insulator surface states with broken\ntime-reversal symmetry and develop a theory for the dynamical Hall effect\ndriven by intense electromagnetic field. The influence of optical Stark effect\nenters as nonlinear dependence on the optical field in the resulting Faraday\n$\\theta_F$ and Kerr $\\theta_K$ rotations. This nonlinear correction is found to\ndecrease $\\theta_F$ with the strength of the A.C. electric field, whereas\n$\\theta_K$ exhibits a non-monotonic behavior. We also assess the effects of\nrelaxation and dephasing on the Hall and magneto-optical responses when the\nfrequency detuning is comparable to the inverse lifetime of the conduction\nelectrons."
    },
    {
        "anchor": "Charge carrier injection electroluminescence with CO functionalized tips\n  on single molecular emitters: We investigate electroluminescence of single molecular emitters on NaCl on\nAg(111) and Au(111) with submolecular resolution in a low-temperature scanning\nprobe microscope with tunneling current, atomic force and light detection\ncapabilities. Role of the tip state is studied in the photon maps of a\nprototypical emitter, zinc phthalocyanine (ZnPc), using metal and CO-metal\ntips. CO-functionalization is found to have a dramatic impact on the resolution\nand contrast of the photon maps due to the localized overlap of the p-orbitals\non the tip with the molecular orbitals of the emitter. The possibility of using\nthe same CO-functionalized tip for tip-enhanced photon detection and high\nresolution atomic force is demonstrated. We study the electroluminescence of\nZnPc, induced by charge carrier injection at sufficiently high bias voltages.\nWe propose that the distinct level alignment of the ZnPc frontier orbital with\nthe Au(111) and Ag(111) Fermi levels governs the primary excitation mechanisms\nas the injection of electrons and holes from the tip into the molecule,\nrespectively. These findings put forward the importance of the tip status in\nthe photon maps and contribute to a better understanding of the photophysics of\norganic molecules on surfaces.",
        "positive": "Impact of dimensional crossover on phonon transport in van der Waals\n  materials: a case study of graphite and graphene: Using first-principles modeling, we investigate how phonon transport evolves\nin layered/van der Waals materials when going from 3D to 2D, or vice versa, by\ngradually pulling apart the atomic layers in graphite to form graphene. Focus\nis placed on identifying the features impacting thermal conductivity that are\nlikely shared with other layered materials. The thermal conductivity $\\kappa$\nof graphite is found to be lower than that of graphene mainly due to changes in\nthe phonon dispersion driven by van der Waals coupling. Specifically, as the\natomic layers are brought closer together, the acoustic flexural phonons in\ngraphene form low-energy optical flexural phonons in graphite that possess\nlower in-plane velocities, density-of-states and phonon occupation, thus\nreducing $\\kappa$. Similar dispersion changes, and impact on thermal\nconductivity, can be expected in other van der Waals materials when\ntransitioning from 2D to 3D. Our findings also indicate that the selection\nrules in graphene, which reduce phonon-phonon scattering and contribute to its\nlarge $\\kappa$, effectively hold as the atomic layers are brought together to\nform graphite. While the selection rules do not strictly apply to graphite, in\npractice similar scattering behavior is displayed due in part to the weak\ninter-layer coupling. This suggests that van der Waals materials, in bulk 3D\nform, may have lower phonon-phonon scattering rates than other non-layered bulk\nmaterials."
    },
    {
        "anchor": "Quantized chiral edge conduction on reconfigurable domain walls of a\n  magnetic topological insulator: The electronic orders in magnetic and dielectric materials form the domains\nwith different signs of order parameters. The control of configuration and\nmotion of the domain walls (DWs) enables gigantic, nonvolatile responses\nagainst minute external fields, forming the bases of contemporary electronics.\nAs an extension of the DW function concept, we realize the one-dimensional\nquantized conduction on the magnetic DWs of a topological insulator (TI). The\nDW of a magnetic TI is predicted to host the chiral edge state (CES) of\ndissipation-less nature when each magnetic domain is in the quantum anomalous\nHall state. We design and fabricate the magnetic domains in a magnetic TI film\nwith the tip of the magnetic force microscope, and clearly prove the existence\nof the chiral one-dimensional edge conduction along the prescribed DWs. The\nproof-of-concept devices based on the reconfigurable CES and Landauer-Buttiker\nformalism are exemplified for multiple-domain configurations with the\nwell-defined DW channels.",
        "positive": "Thermally stable magnetic skyrmions in multilayer synthetic\n  antiferromagnetic racetracks: A magnetic skyrmion is a topological magnetization structure with a\nnanometric size and a well-defined swirling spin distribution, which is\nanticipated to be an essential building block for novel skyrmion-based device\napplications. We study the motion of magnetic skyrmions in multilayer synthetic\nantiferromagnetic (SAF) racetracks as well as in conventional monolayer\nferromagnetic (FM) racetracks at finite temperature. There is an odd-even\neffect of the constituent FM layer number on the skyrmion Hall effect (SkHE).\nNamely, due to the suppression of the SkHE, the magnetic skyrmion has no\ntransverse motion in multilayer SAF racetracks packed with even FM layers. It\nis shown that a moving magnetic skyrmion is stable even at room temperature\n($T=300$ K) in a bilayer SAF racetrack but it is destructed at $T=100$ K in a\nmonolayer FM racetrack. Our results indicate that the SAF structures are\nreliable and promising candidates for future applications in\nskyrmion-electronics and skyrmion-spintronics."
    },
    {
        "anchor": "Dynamical Backaction Cooling with Free Electrons: The ability to cool single ions, atomic ensembles, and more recently\nmacroscopic degrees of freedom down to the quantum groundstate has generated\nconsiderable progress and perspectives in Basic and Technological Science.\nThese major advances have been essentially obtained by coupling mechanical\nmotion to a resonant electromagnetic degree of freedom in what is generally\nknown as laser cooling. In this work, we experimentally demonstrate the first\nself-induced coherent cooling mechanism that is not mediated by the\nelectromagnetic field. Using a focused electron beam, we report a 50-fold\nreduction of the motional temperature of a nanowire. Our result primarily\nrelies on the sub-nanometer confinement of the electron beam and generalizes to\nany delayed and topologically confined interaction, with important consequences\nfor near-field microscopy and fundamental nanoscale dissipation mechanisms.",
        "positive": "Control of Coherent Acoustic Phonons: Using sub-picosecond optical pump-probe techniques, coherent zone-folded\nlongitudinal acoustic phonons (ZFLAPs) were generated and controlled in an\nInGaN multiple quantum well structure. A one-pump, one-probe differential\ntransmission technique revealed that carriers injected near the barrier band\nedge were quickly captured into the quantum wells and generated strong coherent\nZFLAP oscillations. Two-pump differential transmission was used to generate and\ncontrol coherent ZFLAP oscillations through the relative timing and amplitude\nof the two pump pulses. Enhancement and suppression of ZFLAP oscillations were\ndemonstrated, including complete cancellation of generated acoustic phonons for\nthe first time in any material system. Coherent control was used to demonstrate\nthat ZFLAPs are generated differently in InGaN multiple quantum wells than in\nGaAs/AlAs superlattices."
    },
    {
        "anchor": "Spin to charge conversion at Rashba-split SrTiO$_3$ interfaces from\n  resonant tunneling: Spin-charge interconversion is a very active direction in spintronics. Yet,\nthe complex behaviour of some of the most promising systems such as SrTiO$_3$\n(STO) interfaces is not fully understood. Here, on the basis of a 6-band\n$\\boldsymbol{k.p}$ method combined with spin-resolved scattering theory, we\ngive a theoretical demonstration of transverse spin-charge interconversion\nphysics in STO Rashba interfaces. Calculations involve injection of spin\ncurrent from a ferromagnetic contact by resonant tunneling into the native\nRashba-split resonant levels of the STO triangular quantum well. We compute an\nasymmetric tunneling electronic transmission yielding a transverse charge\ncurrent flowing in plane, with a dependence with gate voltage in a very good\nagreement with existing experimental data.",
        "positive": "Resolving complex spin textures in nanoparticles by magnetic neutron\n  scattering: In the quest to image the three-dimensional magnetization structure we show\nthat the technique of magnetic small-angle neutron scattering (SANS) is highly\nsensitive to the details of the internal spin structure of nanoparticles. By\ncombining SANS with numerical micromagnetic computations we study the\ntransition from single-domain to multi-domain behavior in nanoparticles and its\nimplications for the ensuing magnetic SANS cross section. Above the critical\nsingle-domain size we find that the cross section and the related correlation\nfunction cannot be described anymore with the uniform particle model, resulting\ne.g. in deviations from the well-known Guinier law. We identify a clear\nsignature for the occurrence of a vortex-like spin structure at remanence. The\nmicromagnetic approach to magnetic SANS bears great potential for future\ninvestigations, since it provides fundamental insights into the mesoscale\nmagnetization profile of nanoparticles."
    },
    {
        "anchor": "Comment on: ``Zero temperature conductance of parallel T-shape double\n  quantum dots'' [Physica E 39 (2007) 214, arXiv:0708.1842v1]: In a recent paper [Physica E 39 (2007) 214, arXiv:0708.1842v1] Crisan, Grosu\nand Tifrea revisited the problem of the conductance through a double quantum\ndot molecule connected to electrodes in a T-shape configuration. The authors\nobtained an expression for the conductance that disagrees with previous results\nin the literature. We point out an error in their derivation of the conductance\nformula and show that it gives unphysical results even for non-interacting\nquantum dots.",
        "positive": "Persistent charge and spin currents in the long wavelength regime for\n  graphene rings: We address the problem of persistent charge and spin currents on a Corbino\ndisk built from a graphene sheet. We consistently derive the Hamiltonian\nincluding kinetic, intrinsic (ISO) and Rashba spin-orbit interactions in\ncylindrical coordinates. The Hamiltonian is carefully considered to reflect\nhermiticity and covariance. We compute the energy spectrum and the\ncorresponding eigenfunctions separately for the intrinsic and Rashba spin-orbit\ninteractions. In order to determine the charge persistent currents we use the\nspectrum equilibrium linear response definition. We also determine the spin and\npseudo spin polarizations associated with such equilibrium currents. For the\nintrinsic case one can also compute the correct currents by applying the bare\nvelocity operator to the ISO wavefunctions or alternatively the ISO group\nvelocity operator to the free wavefunctions. Charge currents for both SO\ncouplings are maximal in the vicinity of half integer flux quanta. Such maximal\ncurrents are protected from thermal effects because contributing levels plunge\n($\\sim$1K) into the Fermi sea at half integer flux values. Such a mechanism,\nmakes them observable at readily accessible temperatures. Spin currents only\narise for the Rashba coupling, due to the spin symmetry of the ISO spectrum.\nFor the Rashba coupling, spin currents are cancelled at half integer fluxes but\nthey remain finite in the vicinity, and the same scenario above protects spin\ncurrents."
    },
    {
        "anchor": "Non-conservative current-driven dynamics: beyond the nanoscale: Long metallic nanowires combine crucial factors for non-conservative\ncurrent-driven atomic mo- tion. These systems have degenerate vibrational\nfrequencies, clustered about a Kohn anomaly in the dispersion relation, that\ncan couple under current to form non-equilibrium modes of motion growing\nexponentially in time. Such motion is made possible by non-conservative\ncurrent-induced forces on atoms, and we refer to it generically as the\nwaterwheel effect. Here the connection be- tween the waterwheel effect and the\nstimulated directional emission of phonons propagating along the electron flow\nis discussed in an intuitive manner. Non-adiabatic molecular dynamics show that\nwaterwheel modes self-regulate by reducing the current and by populating modes\nnearby in fre- quency, leading to a dynamical steady state in which\nnon-conservative forces are counter-balanced by the electronic friction. The\nwaterwheel effect can be described by an appropriate effective non- equilibrium\ndynamical response matrix. We show that the current-induced parts of this\nmatrix in metallic systems are long-ranged, especially at low bias. This\nnon-locality is essential for the characterisation of non-conservative atomic\ndynamics under current beyond the nanoscale.",
        "positive": "Transverse field effect in graphene ribbons: It is shown that a graphene ribbon, a ballistic strip of carbon monolayer,\nmay serve as a quantum wire whose electronic properties can be continuously and\nreversibly controlled by an externally applied transverse voltage. The electron\nbands of armchair-edge ribbons undergo dramatic transformations: The Fermi\nsurface fractures, Fermi velocity and effective mass change sign, and\nexcitation gaps are reduced by the transverse field. These effects are manifest\nin the conductance plateaus, van Hove singularities, thermopower, and activated\ntransport. The control over one-dimensional bands may help enhance effects of\nelectron correlations, and be utilized in device applications."
    },
    {
        "anchor": "Electronic properties of armchair AA-stacked bilayer graphene\n  nanoribbons: We study analytically, based on the tight-binding model, the electronic band\nstructure of armchair AA-stacked bilayer graphene nanoribbons (BLGNRs) in\nseveral regimes. We apply hard-wall boundary conditions to determine the\ndiscretion dominating on the Bloch wavefunctions in the confined direction.\nFirst we consider an ideal case, perfect nanoribbons without any edge\ndeformation, and show that their electronic properties are strongly\nsize-dependent. We find that the narrow armchair AA-stacked BLGNRs (similar to\nsingle-layer graphene nanoribbons) may be metallic or semiconducting depending\non their width determined by the number of dimer lines across the ribbon width,\nwhile the wide ribbons are metallic. Then we show that, when the edge\ndeformation effects are taken into account, all narrow armchair AA-stacked\nBLGNRs become semiconducting while the wide ribbons remain metallic. We also\ninvestigate effects of an electric filed applied perpendicular to the\nnanoribbon layers and show it can be used to tune the electronic properties of\nthese nanoribbons leading to a semiconducting-to-metallic phase transition at a\ncritical value of the electric field which depends on the nanoribbon width.\nFurthermore, in all regimes, we calculate the corresponding wavefunctions which\ncan be used to investigate and predict various properties in these nanoribbons.",
        "positive": "Dephasing by electron-electron interactions in a ballistic Mach-Zehnder\n  interferometer: We consider a ballistic Mach-Zehnder interferometer for electrons propagating\nchirally in one dimension (such as in an integer Quantum Hall effect edge\nchannel). In such a system, dephasing occurs when the finite range of the\ninteraction potential is taken into account. Using the tools of bosonization,\nwe discuss the decay of coherence as a function of propagation distance and\nenergy. We supplement the exact solution by a semiclassical approach that is\nphysically transparent and is exact at high energies. In particular, we study\nin more detail the recently predicted universal power-law decay of the\ncoherence at high energies, where the exponent does not depend on the\ninteraction strength. In addition, we compare against Keldysh perturbation\ntheory, which works well for small interaction strength at short propagation\ndistances."
    },
    {
        "anchor": "Macroscopic quantum tunneling in magnetic nanostructures: Theoretical foundations of the problem of quantum spin tunneling in magnetic\nnanostructures are presented. Several model problems are considered in detail,\nincluding recent new results on tunneling in antiferromagnetic nanoparticles\nand topologically nontrivial magnetic structures in systems with reduced\ndimension.",
        "positive": "Electrostatics of metal-graphene interfaces: sharp p-n junctions for\n  electron-optical applications: Creation of sharp lateral p-n junctions in graphene devices, with transition\nwidths well below the Fermi wavelength of graphene charge carriers, is vital to\nstudy and exploit these electronic systems for electron-optical applications.\nThe achievement of such junctions is, however, not trivial due to the presence\nof a considerable out-of-plane electric field in lateral p-n junctions,\nresulting in large widths. Metal-graphene interfaces represent a novel,\npromising and easy to implement technique to engineer such sharp lateral p-n\njunctions in graphene field-effect devices, in clear contrast to the much wider\n(i.e. smooth) junctions achieved via conventional local gating. In this work,\nwe present a systematic and robust investigation of the electrostatic problem\nof metal-induced lateral p-n junctions in gated graphene devices for\nelectron-optics applications, systems where the width of the created junctions\nis not only determined by the metal used but also depends on external factors\nsuch as device geometries, dielectric environment and different operational\nparameters such as carrier density and temperature. Our calculations\ndemonstrate that sharp junctions can be achieved via metal-graphene interfaces\nat room temperature in devices surrounded by dielectric media with low relative\npermittivity. In addition, we show how specific details such as the separation\ndistance between metal and graphene and the permittivity of the gap in-between\nplays a critical role when defining the p-n junction, not only defining its\nwidth w but also the energy shift of graphene underneath the metal. These\nresults can be extended to any two-dimensional (2D) electronic system doped by\nthe presence of metal clusters and thus are relevant for understanding\ninterfaces between metals and other 2D materials."
    },
    {
        "anchor": "Thermal Transport through a Mesoscopic Weak Link: We calculate the rate of energy flow between two macroscopic bodies, each in\nthermodynamic equilibrium at a different temperature, and joined by a weak\nmechanical link. The macroscopic solids are assumed to be electrically\ninsulating, so that thermal energy is carried only by phonons. To leading order\nin the strength of the weak link, modeled here by a harmonic spring, the\nthermal current is determined by a product of the local vibrational\ndensity-of-states of the two bodies at the points of connection. Our general\nexpression for the thermal current can be regarded as a thermal analog of the\nwell-known formula for the electrical current through a resistive barrier. It\nis also related to the thermal Landauer formula in the weak-tunneling limit.\nImplications for heat transport experiments on dielectric quantum\npoint-contacts are discussed.",
        "positive": "One-Dimensional Edge Contact to Encapsulated MoS2 with a Superconductor: Establishing ohmic contact to van der Waals semiconductors such as MoS2 is\ncrucial to unlocking their full potential in next-generation electronic\ndevices. Encapsulation of few layer MoS2 with hBN preserves the material's\nelectronic properties but makes electrical contacts more challenging. Progress\ntoward high quality edge contact to encapsulated MoS2 has been recently\nreported. Here, we evaluate a contact methodology using sputtered MoRe, a Type\nII superconductor with a relatively high critical field and temperature\ncommonly used to induce superconductivity in graphene. We find that the contact\ntransparency is poor and that the devices do not support a measurable\nsupercurrent down to 3 Kelvin, which has ramifications for future fabrication\nrecipes."
    },
    {
        "anchor": "Phase shifts and phase $\u03c0$-jumps in four-terminal waveguide\n  Aharonov-Bohm interferometers: Quantum coherent properties of electrons can be studied in Aharonov-Bohm (AB)\ninterferometers. We investigate both experimentally and theoretically the\ntransmission phase evolution in a four-terminal quasi-one-dimensional\nAlGaAs/GaAs-based waveguide AB ring. As main control parameter besides the\nmagnetic field, we tune the Fermi wave number along the pathways using a\ntop-gate. Our experimental results and theoretical calculations demonstrate the\nstrong influence of the measurement configuration upon the\nAB-resistance-oscillation phase in a four-terminal device. While the non-local\nsetup displays continuous phase shifts of the AB oscillations, the phase\nremains rigid in the local voltage-probe setup. Abrupt phase jumps are found in\nall measurement configurations. We analyze the phase shifts as functions of the\nmagnetic field and the Fermi energy and provide a detailed theoretical model of\nthe device. Scattering and reflections in the arms of the ring are the source\nof abrupt phase jumps by $\\pi$.",
        "positive": "A Quantum-Chemical Simulation of the Cadmium Chalcogenide Clusters\n  Terminated with Hydrogen and Simple Functional Groups: Ab initio calculations of cadmium chalcogenide nanoclusters with terminating\ngroups (H, O, N, and C atoms bound to the surface sulfur) are considered as a\nsimulation for the species produced in typical synthesis of bio-conjugates with\nluminescent quantum dots. The approaches based on the Hartree-Fock (HF) method\nand density functional theory (DFT) are used assuming geometry optimization\nkeeping the tetrahedral symmetry. The geometry and electronic structure of CdX\n(X=S, Se, Te) clusters with size up to Cd17 (HF) and Cd4 (DFT) bound with\nhydrogen and -OH, -NH2, -CH3, and -CH2CH3 groups are calculated and the effects\nof the terminating groups upon core clusters are discussed."
    },
    {
        "anchor": "Interplay between spin wave and magnetic vortex: In this paper, the interplay between spin wave and magnetic vortex is\nstudied. We find three types of magnon scatterings: skew scattering, symmetric\nside deflection and back reflection, which associate with respectively magnetic\ntopology, energy density distribution and linear momentum transfer torque\nwithin vortex. The vortex core exhibits two translational modes: the intrinsic\ncircular mode and a coercive elliptical mode, which can be excited based on\npermanent and periodic magnon spin-transfer torque effects of spin wave.\nLastly, we propose a vortex-based spin wave valve in which via inhomogeneity\nmodulation we access arbitrary control of the phase shift.",
        "positive": "Interplay of localisation and competing interaction channels: cascade of\n  quantum phase transitions: We investigate the interplay of localization, interactions and (pseudo)spin\ndegrees of freedom on quantum states of particles on the lattice. Our results\nshow that breaking the paradigm density-density interaction $U_0\\gg$\n(pseudo)spin-(pseudo)spin interaction $U_s$ will drive the sequence of quantum\nphase transitions (QPT), where (pseudo)spin state and particle ordering, in\ncase of several particle species, on the lattice are strongly changed. QPT\ndriven by competing interactions, $|U_s|\\sim U_0$, manifest itself in\nsingularities of effective exchange integrals. $|U_s|\\sim U_0$ implies a\nfrustration when the interactions standing alone drive the system to different\nphases. Even at $U_s=0$, there is typically a QPT induced by $U_s$ sign change.\nVector cold atoms, Fermions or Bosons, on optical lattices are the\nstate-of-the-art realization of our system where $U_s$ is tunable \\textit{in\nsitu}."
    },
    {
        "anchor": "Voltage-controlled tunneling anisotropic magneto-resistance of a\n  ferromagnetic $p^{++}$-(Ga,Mn)As/$n^{+}$-GaAs Zener-Esaki diode: The large tunneling anisotropic magneto-resistance of a single\n$p^{++}$-(Ga,Mn)As/$n^{+}$-GaAs Zener-Esaki diode is evidenced in a\nperpendicular magnetic field over a large temperature and voltage range. Under\nan applied bias, the tunnel junction transparency is modified, allowing to\ncontinuously tune anisotropic transport properties between the tunneling and\nthe ohmic regimes. Furthermore, an asymmetric bias-dependence of the\nanisotropic tunneling magneto-resistance is also observed: a reverse bias\nhighlights the full (Ga,Mn)As valence band states contribution, whereas a\nforward bias only probes part of the density of states and reveals opposite\ncontributions from two subbands.",
        "positive": "Comment on \"Direct Measurement of Auger Electrons Emitted from a\n  Semiconductor Light-Emitting Diode under Electrical Injection: Identification\n  of the Dominant Mechanism for Efficiency Droop\" [Phys. Rev. Lett. 110, 177406\n  (2013)]: In a recent letter [Phys. Rev. Lett. 110, 177406 (2013)], presenting a\nspectroscopic study of the electrons emitted from the GaN p-cap of a\nforward-biased InGaN/GaN light-emitting diode (LED), the authors observed at\nleast two distinct peaks in the electron energy distribution curves (EDCs),\nseparated by about 1.5 eV, and concluded that the only viable explanation for\nthe higher-energy peak was Auger recombination in the LED active region. We\npresent full-band Monte Carlo simulations suggesting that the higher-energy\npeaks in the measured EDCs are probably uncorrelated with the carrier\ndistribution in the active region. This would not imply that Auger\nrecombination, and possibily Auger-induced leakage, play a negligible role in\nLED droop, but that an Auger signature cannot be recovered from the experiment\nperformed on the LED structure under study. We discuss, as an alternative\nexplanation for the observed EDCs, carrier heating by the electric field in the\nband-bending region."
    },
    {
        "anchor": "Impact of high-frequency pumping on anomalous finite-size effects in\n  three-dimensional topological insulators: Lowering of the thickness of a thin-film three-dimensional topological\ninsulator down to a few nanometers results in the gap opening in the spectrum\nof topologically protected two-dimensional surface states. This phenomenon,\nwhich is referred to as the anomalous finite-size effect, originates from\nhybridization between the states propagating along the opposite boundaries. In\nthis work, we consider a bismuth-based topological insulator and show how the\ncoupling to an intense high-frequency linearly polarized pumping can further be\nused to manipulate the value of a gap. We address this effect within recently\nproposed Brillouin-Wigner perturbation theory that allows us to map a\ntime-dependent problem into a stationary one. Our analysis reveals that both\nthe gap and the components of the group velocity of the surface states can be\ntuned in a controllable fashion by adjusting the intensity of the driving field\nwithin an experimentally accessible range and demonstrate the effect of\nlight-induced band inversion in the spectrum of the surface states for high\nenough values of the pump.",
        "positive": "Observation of mode splitting in artificial spin ice: We report the dependence of the magnetization dynamics in a square artificial\nspin-ice lattice on the in-plane magnetic field angle. Using two complementary\nmeasurement techniques - broadband ferromagnetic resonance and micro-focused\nBrillouin light scattering spectroscopy - we systematically study the evolution\nof the lattice dynamics, both for a coherent radiofrequency excitation and an\nincoherent thermal excitation of spin dynamics. We observe a splitting of modes\nfacilitated by inter-element interactions that can be controlled by the\nexternal field angle and magnitude. Detailed time-dependent micromagnetic\nsimulations reveal that the split modes are localized in different regions of\nthe square network. This observation suggests that it is possible to\ndisentangle modes with different spatial profiles by tuning the external field\nconfiguration."
    },
    {
        "anchor": "Magnetoresistance originated from charge-spin conversion in ferromagnet: Transverse magnetoresistance in a ferromagnetic/nonmagnetic/ferromagnetic\ntrilayer originated from charge-spin conversion by anomalous Hall effect is\ninvestigated theoretically. Solving the spin diffusion equation in bulk and\nusing the spin-dependent Landauer formula at the ferromagnetic/nonmagnetic\ninterface, an analytical formula of the transverse resistivity is obtained. The\ncharge-spin conversion by the anomalous Hall effect contributes to the\nmagnetoresistance in a manner proportional to the square of the spin anomalous\nHall angle. The angular dependence of the magnetoresistance is basically\nidentical to that of planar Hall effect, but has an additional term which\ndepends on the relative angle of the magnetizations in two ferromagnets.",
        "positive": "Spin splitting of electron states in lattice-mismatched (110)-oriented\n  quantum wells: We show that for lattice-mismatched zinc-blende-type (110)-grown quantum\nwells a significant contribution to the zero-magnetic-field spin splitting of\nelectron subbands comes from strain-induced spin-orbit coupling. Combining\nenvelope function theory and atomistic tight-binding approach we calculate\nspin-orbit splitting constants for realistic quantum wells. It is found that\nthe strain due to lattice mismatch in conventional GaAs/AlGaAs structures may\nnoticeably modify the spin splitting while in InGaAs/GaAs structures it plays a\nmajor role and may even change the sign of the spin splitting constant."
    },
    {
        "anchor": "Effect of d-f hybridization on the Josephson current through\n  Eu-chalcogenides: A superconducting ring with a pi junction made from\nsuperconductor/ferromagnetic-metal/superconductor (S-FM-S) exhibits a\nspontaneous current without an external magnetic field in the ground state.\nSuch pi ring provides so-called quiet qubit that can be efficiently decoupled\nfrom the fluctuation of the external field. However, the usage of the FM gives\nrise to strong Ohmic dissipation. Therefore, the realization of pi junctions\nwithout FM is expected for qubit applications. We theoretically consider the\npossibility of the pi coupling for S/Eu-chalcogenides/S junctions based on the\nd-f Hamiltonian. By use of the Green's function method we found that pi\njunction can be formed in the case of the finite d-f hybridization between the\nconduction d and the localized f electrons.",
        "positive": "Spin Seebeck devices using local on-chip heating: A micro-patterned spin Seebeck device is fabricated using an on-chip heater.\nCurrent is driven through a Au heater layer electrically isolated from a\nbilayer consisting of Fe$_3$O$_4$ (insulating ferrimagnet) and a spin detector\nlayer. It is shown that through this method it is possible to measure the\nlongitudinal spin Seebeck effect (SSE) for small area magnetic devices,\nequivalent to traditional macroscopic SSE experiments. Using a lock-in\ndetection technique it is possible to more sensitively characterize both the\nSSE and the anomalous Nernst effect (ANE), as well as the inverse spin Hall\neffect in various spin detector materials. By using the spin detector layer as\na thermometer, we can obtain a value for the temperature gradient across the\ndevice. These results are well matched to values obtained through\nelectromagnetic/thermal modeling of the device structure and with large area\nspin Seebeck measurements."
    },
    {
        "anchor": "Twistronics versus straintronics in twisted bilayers of graphene and\n  transition metal dichalcogenides: Several numerical studies have shown that the electronic properties of\ntwisted bilayers of graphene (TBLG) and transition metal dichalcogenides (TMDs)\nare tunable by strain engineering of the stacking layers. In particular, the\nflatness of the low-energy moir\\'e bands of the rigid and the relaxed TBLG was\nfound to be, substantially, sensitive to the strain. However, to the best of\nour knowledge, there are no full analytical calculations of the effect of\nstrain on such bands. We derive, based on the continuum model of moir\\'e flat\nbands, the low-energy Hamiltonian of twisted homobilayers of graphene and TMDs\nunder strain at small twist angles. We obtain the analytical expressions of the\nstrain-renormalized Dirac velocities and explain the role of strain in the\nemergence of the flat bands. We discuss how strain could correct the twist\nangles and bring them closer to the magic angle $\\theta_m\\sim1.05^{\\circ}$ of\nTBLG and how it may reduce the widths of the lowest-energy bands at charge\nneutrality of the twisted homobilayer of TMDs. The analytical results are\ncompared with numerical and experimental findings and also with our numerical\ncalculations based on the continuum model.",
        "positive": "Relaxation of the Excited Rydberg States of Surface Electrons on Liquid\n  Helium: We report the first direct observation of the decay of the excited-state\npopulation in electrons trapped on the surface of liquid helium. The relaxation\ndynamics, which are governed by inelastic scattering processes in the system,\nare probed by the real-time response of the electrons to a pulsed microwave\nexcitation. Comparison with theoretical calculations allows us to establish the\ndominant mechanisms of inelastic scattering for different temperatures. The\nlongest measured relaxation time is around 1 us at the lowest temperature of\n135 mK, which is determined by the inelastic scattering due to the spontaneous\ntwo-ripplon emission process. Furthermore, the image-charge response shortly\nafter applying microwave radiation reveals interesting population dynamics due\nto the multisubband structure of the system."
    },
    {
        "anchor": "Universal Braess paradox in open quantum dots: We present analytical and numerical results that demonstrate the presence of\nthe Braess paradox in chaotic quantum dots. The paradox that we identify,\noriginally perceived in classical networks, shows that the addition of more\ncapacity to the network can suppress the current flow in the universal regime.\nWe investigate the weak localization term, showing that it presents the paradox\nencoded in a saturation minimum of the conductance, under the presence of\nhyperflow in the external leads. In addition, we demonstrate that the weak\nlocalization suffers a transition signal depending on the overcapacity lead and\npresents an echo on the magnetic crossover before going to zero due to the full\ntime-reversal symmetry breaking.We also show that the quantum interference\ncontribution can dominate the Ohm term in the presence of constrictions and\nthat the corresponding Fano factor engenders an anomalous behavior",
        "positive": "Vortex dynamics of charge carriers in the quasirelativistic graphene\n  model : high-energy $\\vec k\\cdot \\vec p$ approximation: Within the earlier developed high-energy-$\\vec k\\cdot \\vec p$-Hamiltonian\napproach to describe graphene-like materials the simulations of non-Abelian Zak\nphases and band structure of the quasi-relativistic graphene model with a\nflavors number $N=3$ have been performed in approximations with %of zero- and\nnon-zero values of and without gauge fields (flavors). It has been shown that a\nZak-phases set for non-Abelian Majorana-like excitations (modes) in Dirac\nvalleys of the quasirelativistic graphene model is the cyclic group\n$\\mathbf{Z}_{12}$. This group is deformed into $\\mathbf{Z}_8$ at sufficiently\nhigh momenta due to deconfinement of the modes. Since the deconfinement removes\nthe degeneracy of the eightfolding valleys, Weyl nodes and antinodes emerge. We\noffer that a Majorana-like mass term of the quasirelativistic model effects on\nthe graphene band structure in a following way. Firstly the inverse symmetry\nemerges at \"switching on\"\\ of the mass term, and secondly the mass term shifts\nthe location of Weyl nodes and antinodes into the region of higher energies and\naccordingly the Majorana-like modes can exist without mixing with the nodes."
    },
    {
        "anchor": "Interplay of Aharonov-Bohm and Berry phases in gate-defined graphene\n  quantum dots: We study the influence of a magnetic flux tube on the possibility to\nelectrostatically confine electrons in a graphene quantum dot. Without magnetic\nflux tube, the graphene pseudospin is responsible for a quantization of the\ntotal angular momentum to half-integer values. On the other hand, with a flux\ntube containing half a flux quantum, the Aharonov-Bohm phase and Berry phase\nprecisely cancel, and we find a state at zero angular momentum that cannot be\nconfined electrostatically. In this case, true bound states only exist in\nregular geometries for which states without zero-angular-momentum component\nexist, while non-integrable geometries lack confinement. We support these\narguments with a calculation of the two-terminal conductance of a gate-defined\ngraphene quantum dot, which shows resonances for a disc-shaped geometry and for\na stadium-shaped geometry without flux tube, but no resonances for a\nstadium-shaped quantum dot with a $\\pi$-flux tube.",
        "positive": "Nuclear spin driven resonant tunnelling of magnetisation in Mn12 acetate: Current theories still fail to give a satisfactory explanation of the\nobserved quantum phenomena in the relaxation of the magnetisation of the\nmolecular cluster Mn12 acetate. In the very low temperature regime, Prokof'ev\nand Stamp recently proposed that slowly changing dipolar fields and rapidly\nfluctuating hyperfine fields play a major role in the tunnelling process. By\nmeans of a faster relaxing minor species of Mn12ac and a new experimental 'hole\ndigging' method, we measured the intrinsic line width broadening due to local\nfluctuating fields, and found strong evidence for the influence of nuclear\nspins on resonance tunnelling at very low temperatures (0.04 - 0.3K). At higher\ntemperature (1.5 - 4K), we observed a homogeneous line width broadening of the\nresonance transitions being in agreement with a recent calculation of\nLeuenberger and Loss."
    },
    {
        "anchor": "What retards the response of graphene based gaseous sensor: Graphene based sensor to gas molecules should be ultrasensitive and ultrafast\nbecause of the single-atomic thickness of graphene, while the response is not\nfast. Usually, the measured response time for many molecules, such as CO, NH3,\nSO2, CO2 and NO2 and so on, is on the scale of minutes or longer. In the\npresent work, we found via \\emph{ab initio} calculations there exists a\npotential barrier larger than 0.7 eV that hinders the gas molecule to land\ndirectly at the defective sites of graphene and retards the response. An\nefficient approach to the problem is suggested as modifying the graphene sheet\nwith other molecules to reduce the potential barrier and was demonstrated by a\ngraphene sheet modified by Fe2O3 molecules that shows fast response to H2S\nmolecule, and the calculated response time is close to the measured one, 500\n$\\mu$s.",
        "positive": "Effect of electron-phonon interaction on spectroscopies in graphene: We calculate the effect of the electron-phonon interaction on the electronic\ndensity of states (DOS), the quasiparticle properties and on the optical\nconductivity of graphene. In metals with DOS constant on the scale of phonon\nenergies, the electron-phonon renormalizations drop out of the dressed DOS,\nhowever, due to the Dirac nature of the electron dynamics in graphene, the band\nDOS is linear in energy and phonon structures remain, which can be emphasized\nby taking an energy derivative. There is a shift in the chemical potential and\nin the position in energy of the Dirac point. Also, the DOS can be changed from\na linear dependence out of value zero at the Dirac point to quadratic out of a\nfinite value. The optical scattering rate $1/\\tau$ sets the energy scale for\nthe rise of the optical conductivity from its universal DC value $4e^2/\\pi h$\n(expected in the simplest theory when chemical potential and temperature are\nboth $\\ll 1/2\\tau$) to its universal AC background value $(\\sigma_0=\\pi\ne^2/2h)$. As in ordinary metals the DC conductivity remains unrenormalized\nwhile its AC value is changed. The optical spectral weight under the intraband\nDrude is reduced by a mass renormalization factor as is the effective\nscattering rate. Optical weight is transferred to an Holstein phonon-assisted\nside band. Due to Pauli blocking the interband transitions are sharply\nsuppressed, but also nearly constant, below twice the value of renormalized\nchemical potential and also exhibit a phonon-assisted contribution. The\nuniversal background conductivity is reduced below $\\sigma_0$ at large\nenergies."
    },
    {
        "anchor": "Near-Surface Electrical Characterisation of Silicon Electronic Devices\n  Using Focused keV Ions: The demonstration of universal quantum logic operations near the\nfault-tolerance threshold establishes ion-implanted near-surface donor atoms as\na plausible platform for scalable quantum computing in silicon. The next\ntechnological step forward requires a deterministic fabrication method to\ncreate large-scale arrays of donors, featuring few hundred nanometre\ninter-donor spacing. Here, we explore the feasibility of this approach by\nimplanting low-energy ions into silicon devices featuring an enlarged 60x60\n$\\mu$m sensitive area and an ultra-thin 3.2 nm gate oxide - capable of hosting\nlarge-scale donor arrays. By combining a focused ion beam system incorporating\nan electron-beam-ion-source with in-vacuum ultra-low noise ion detection\nelectronics, we first demonstrate a versatile method to spatially map the\ndevice response characteristics to shallowly implanted 12 keV $^1$H$_2^+$ ions.\nDespite the weak internal electric field, near-unity charge collection\nefficiency is obtained from the entire sensitive area. This can be explained by\nthe critical role that the high-quality thermal gate oxide plays in the ion\ndetection response, allowing an initial rapid diffusion of ion induced charge\naway from the implant site. Next, we adapt our approach to perform\ndeterministic implantation of a few thousand 24 keV $^{40}$Ar$^{2+}$ ions into\na predefined micro-volume, without any additional collimation. Despite the\nreduced ionisation from the heavier ion species, a fluence-independent\ndetection confidence of $\\geq$99.99% was obtained. Our system thus represents\nnot only a new method for mapping the near-surface electrical landscape of\nelectronic devices, but also an attractive framework towards mask-free\nprototyping of large-scale donor arrays in silicon.",
        "positive": "The role of Rashba spin-orbit induced spin textures in the anomalous\n  Josephson effect: This work reports the theoretical investigation into the mechanism\nunderpinning the anomalous Josephson effect. The prototypical system we study\nis a ballistic two-dimensional junction containing a two-dimensional Rashba\nspin-orbit interaction. In this paper we demonstrate how this two-dimensional\nRashba interaction mixes the spins of adjacent transverse subbands which leads\nto significant spin-asymmetry within the junction. Under an external magnetic\nfield, applied perpendicular to both the axis of transport and the normal\nvector of the junction, the sinusoidal Josephson current can then experience an\nanomalous phase shift. The role of this spin mixing in the limit of a single\nsub-band is initially explored by deriving an analytical expression for the\nresulting anomalous phase shift. The analysis is then extended to systems with\nmultiple occupied sub-bands; in this later section, starting from a microscopic\nmodel, we derive an analytic formula for the resulting anomalous phase shift\nindicating it is linear in both magnetic field and spin-orbit strength. We then\nverify and validate all findings by comparing them with numerical results\nevaluated by a tight-binding model."
    },
    {
        "anchor": "Tunable heat pump by modulating the coupling to the leads: We follow the nonequilibrium Green's function formalism to study\ntime-dependent thermal transport in a linear chain system consisting of two\nsemi-infinite leads connected together by a coupling that is harmonically\nmodulated in time. The modulation is driven by an external agent that can\nabsorb and emit energy. We determine the energy current flowing out of the\nleads exactly by solving numerically the Dyson equation for the contour-ordered\nGreen's function. The amplitude of the modulated coupling is of the same order\nas the interparticle coupling within each lead. When the leads have the same\ntemperature, our numerical results show that modulating the coupling between\nthe leads may direct energy to either flow into the leads simultaneously or\nflow out of the leads simultaneously, depending on the values of the driving\nfrequency and temperature. A special combination of values of the driving\nfrequency and temperature exists wherein no net energy flows into or out of the\nleads, even for long times. When one of the leads is warmer than the other, net\nenergy flows out of the warmer lead. For the cooler lead, however, the\ndirection of the energy current flow depends on the values of the driving\nfrequency and temperature. In addition, we find transient effects to become\nmore pronounced for higher values of the driving frequency.",
        "positive": "Ultrafast and Strong-Field Physics in Graphene-Like Crystals: Bloch Band\n  Topology and High-Harmonic Generation: The emerging possibilities to steer and control electronic motion on subcycle\ntime scales with strong electric fields enable studying the nonperturbative\noptical response and Bloch bands' topological properties, originated from\nBerry's trilogy: connection, curvature, and phase. This letter introduces a\ntheoretical framework for the nonperturbative electron dynamics in\ntwo-dimensional (2D) crystalline solids induced by the few-cycle and\nstrong-field optical lasers. In the presented model, the expression associated\nwith the Bloch band topology and broken crystal symmetry merges\nself-consistently in the system observables such as High Harmonic Generation\n(HHG). This singles out our work from recent HHG calculations from the\nstrongly-driven systems. Concisely, in our theoretical experiment on 2D\nmaterials in the strong-field optical regime, we show that Bloch band topology\nand broken symmetry manifest themselves in several ways: the momentum-resolved\nattosecond interferometry of electron wave packets, anomalous and chiral\nvelocity in both intraband and interband dynamics, anomalous Hall current and\nrespective HHG highly sensitive to the laser waveform, multiple plateau-cutoff\nstructures in both longitudinal and transverse HHG, the formation of even\nharmonics in the perpendicular polarization with respect to the driving laser,\nsingular jumps across the phase diagram of the HHG, attosecond chirp, and\nultrafast valley polarization induced by the chiral gauge field that is robust\nto lattice imperfections and scattering. The link between HHG and solid-state\nband geometry offers an all-optical reconstruction of electron band structure\nby optical means, and accelerates studies on the non-equilibrium Floquet\nengineering, topologically-protected nonlinear spin and edge currents,\nvalleytronics, quantum computing and high-temperature superconductivity on\nsub-femtosecond time scales."
    },
    {
        "anchor": "High-field charge transport on the surface of Bi$_2$Se$_3$: We present a theoretical study on the high-field charge transport on the\nsurface of Bi$_2$Se$_3$ and reproduce all the main features of the recent\nexperimental results, i.e., the incomplete current saturation and the finite\nresidual conductance in the high applied field regime [Costache {\\it et al.},\nPhys. Rev. Lett. {\\bf 112}, 086601 (2014)]. Due to the hot-electron effect, the\nconductance decreases and the current shows the tendency of the saturation with\nthe increase of the applied electric field. Moreover, the electric field can\nexcite carriers within the surface bands through interband precession and leads\nto a higher conductance. As a joint effect of the hot-electron transport and\nthe carrier excitation, the conductance approaches a finite residual value in\nthe high-field regime and the current saturation becomes incomplete. We thus\ndemonstrate that, contrary to the conjecture in the literature, the observed\ntransport phenomena can be understood qualitatively in the framework of surface\ntransport alone. Furthermore, if a constant bulk conductance which is\ninsensitive to the field is introduced, one can obtain a good quantitative\nagreement between the theoretical results and the experimental data.",
        "positive": "Black and White Holes at Material Junctions: Electrons in Type II Weyl semimetals display one-way propagation, which\nsupports totally reflecting behavior at an endpoint, as one has for black hole\nhorizons viewed from the inside. Junctions of Type I and Type II lead to\nequations identical to what one has near black hole horizons, but the physical\nimplications, we suggest, are quite different from expectations which are\nconventional in that context. The time-reversed, \"white hole\" configuration is\nalso physically accessible."
    },
    {
        "anchor": "Local density of states and Friedel oscillation in graphene: We investigate the local density of states and Friedel oscillation in\ngraphene around a well localized impurity in Born approximation. In our\nanalytical calculations Green's function technique has been used taking into\naccount both the localized atomic wavefunctions in a tight-binding scheme and\nthe corresponding symmetries of the lattice. As a result we obtained long\nwavelength oscillations in the density of electrons with long range behavior\nproportional to the inverse square of the distance from the impurity. These\nleading oscillations are out of phase on nearby lattice sites (in fact for an\nextended defect they cancel each other within one unit cell), therefore a probe\nwith resolution worse than a few unit cells will experience only the next to\nleading inverse cube decay of density oscillations even for a short range\nscatterer.",
        "positive": "Impurity-induced states in superconducting heterostructures: Heterostructures allow the realization of electronic states that are\ndifficult to obtain in isolated systems. Exemplary is the case of\nquasi-one-dimensional heterostructures formed by a superconductor and a\nsemiconductor with spin-orbit coupling in which Majorana zero-energy modes can\nbe realized. We study the effect of a single impurity on the spectrum of\nsuperconducting heterostructures. We find that the coupling between the\nsuperconductor and the semiconductor can strongly affect the impurity-induced\nstates and may induce additional subgap bound states that are not present in\nisolated uniform superconductors. For the case of quasi-one-dimensional\nsuperconductor/semiconductor heterostructures, we obtain the conditions for\nwhich the low-energy impurity-induced bound states appear."
    },
    {
        "anchor": "Entanglement creation in a quantum dot-nanocavity system: We explore the possibility to entangle an excitonic two-level system in a\nsemiconductor quantum dot (QD) with a cavity defined on a photonic crystal by\nsweeping the cavity frequency across its resonance with the exciton transition.\nThe dynamic cavity detuning is established by a radio frequency surface\nacoustic wave (SAW). It induces Landau-Zener (LZ) transitions between the\nexcitonic and the photonic degrees of freedom and thereby creates a\nsuperposition state. We optimize this scheme by using tailored\nFourier-synthesized SAW pulses with up to five harmonics. The theoretical study\nis performed with a master equation approach for present state-of-the-art\nsetups. Assuming experimentally demonstrated system parameters, we demonstrate\nthat the composed pulses increase both the maximum entanglement and its\npersistence. The latter is only limited by the dominant dephasing mechanism;\ni.e., the photon loss from the cavity.",
        "positive": "Dislocation Non-Hermitian Skin Effect: We demonstrate that crystal defects can act as a probe of intrinsic\nnon-Hermitian topology. In particular, in point-gapped systems with periodic\nboundary conditions, a pair of dislocations may induce a non-Hermitian skin\neffect, where an extensive number of Hamiltonian eigenstates localize at only\none of the two dislocations. An example of such a phase are two-dimensional\nsystems exhibiting weak non-Hermitian topology, which are adiabatically related\nto a decoupled stack of Hatano-Nelson chains. Moreover, we show that strong\ntwo-dimensional point-gap topology may also result in a dislocation response,\neven when there is no skin effect present with open boundary conditions. For\nboth cases, we directly relate their bulk topology to a stable dislocation\nnon-Hermitian skin effect. Finally, and in stark contrast to the Hermitian\ncase, we find that gapless non-Hermitian systems hosting bulk exceptional\npoints also give rise to a well-localized dislocation response."
    },
    {
        "anchor": "Topological Magnon Insulator with a Kekule Bond Modulation: We examine the combined effects of a Kekule coupling texture (KC) and a\nDzyaloshinskii-Moriya interaction (DMI) in a two-dimensional ferromagnetic\nhoneycomb lattice. By analyzing the gap closing conditions and the inversions\nof the bulk bands, we identify the parameter range in which the system behaves\nas a trivial or a nontrivial topological magnon insulator. We find four\ntopological phases in terms of the KC parameter and the DMI strength. We\npresent the bulk-edge correspondence for the magnons in a honeycomb lattice\nwith an armchair or a zigzag boundary. Furthermore, we find Tamm-like edge\nstates due to the intrinsic on-site interactions along the boundary sites. Our\nresults may have significant implications to magnon transport properties in the\n2D magnets at low temperatures.",
        "positive": "A dark-field microscope for background-free detection of resonance\n  fluorescence from single semiconductor quantum dots operating in a\n  set-and-forget mode: Optically active quantum dots, for instance self-assembled InGaAs quantum\ndots, are potentially excellent single photon sources. The fidelity of the\nsingle photons is much improved using resonant rather than non-resonant\nexcitation. With resonant excitation, the challenge is to distinguish between\nresonance fluorescence and scattered laser light. We have met this challenge by\ncreating a polarization-based dark-field microscope to measure the resonance\nfluorescence from a single quantum dot at low temperature. We achieve a\nsuppression of the scattered laser exceeding a factor of 10^7 and\nbackground-free detection of resonance fluorescence. The same optical setup\noperates over the entire quantum dot emission range 920-980 nm and also in high\nmagnetic fields. The major development is the outstanding long-term stability:\nonce the dark-field point has been established, the microscope operates for\ndays without alignment. The mechanical and optical design of the microscope is\npresented, as well as exemplary resonance fluorescence spectroscopy results on\nindividual quantum dots to underline the microscope's excellent performance."
    },
    {
        "anchor": "Quasiresonant Excitation of InP/InGaP Quantum Dots Using Second Harmonic\n  Generated in a Photonic Crystal Cavity: Indistinguishable single photons are necessary for quantum information\nprocessing applications. Resonant or quasiresonant excitation of single quantum\ndots provides greater single photon indistinguishability than incoherent\npumping, but is also more challenging experimentally. Here, we demonstrate high\nsignal to noise quasiresonant excitation of InP/InGaP quantum dots. The\nexcitation is provided via second harmonic generated from a telecommunications\nwavelength laser resonant with the fundamental mode of a photonic crystal\ncavity, fabricated at twice the quantum dot transition wavelength. The second\nharmonic is generated using the \\chi(2) nonlinearity of the InGaP material\nmatrix.",
        "positive": "Assessing the reliability of the Raman peak counting method for the\n  characterization of SWCNT diameter distributions: a cross-characterization\n  with TEM: Resonant Raman spectroscopy is a widely used technique for single-walled\ncarbon nanotube (SWCNT) characterization, in particular in the radial breathing\nmode (RBM) range which provides direct information on the structure of the\nnanotube in resonance. The RBM peak counting method, i.e. acquiring Raman\nspectrum grids on a substrate with a select set of discrete laser lines and\ncounting RBM peaks as single nanotubes, is frequently used to characterize\nSWCNT growth samples, despite the many factors that can induce errors in the\nresults. In this work, we cross-characterize the diameter distributions\nobtained through this methodology with diameter distributions obtained by\ncounting SWCNT diameters in transmission electron microscopy (TEM) and discuss\nthe different results and biases between the techniques. This study is\nperformed on a broad diameter distribution sample, and on two\nchirality-enriched samples whose chirality distributions are determined by\nphotoluminescence excitation spectroscopy (PLE) and statistical analysis of\nhigh resolution TEM (HRTEM) images. We show that the largest differences\nbetween the Raman peak counting and TEM diameter distributions stem from the\nchirality-dependence of SWCNT Raman cross-sections and the patchy vision\noffered by the use of only a few discrete excitation wavelengths. The effect of\nthe substrate and TEM-related biases are also discussed."
    },
    {
        "anchor": "Coulomb Blockade Resonances in Quantum Wires: The conductance through a quantum wire of cylindrical cross section and a\nweak bulge is solved exactly for two electrons within the Landauer-Buettiker\nformalism. We show that this 'open' quantum dot exhibits spin-dependent Coulomb\nblockade resonances resulting in two anomalous structure on the rising edge to\nthe first conductance plateau, one near 0.25(2e^2/h), related to a singlet\nresonance, and one near 0.7(2e^2/h), related to a triplet resonance. These\nresonances are generic and robust, occurring for other types of quantum wire\nand surviving to temperatures of a few degrees.",
        "positive": "Basic obstacle for electrical spin-injection from a ferromagnetic metal\n  into a diffusive semiconductor: We have calculated the spin-polarization effects of a current in a two\ndimensional electron gas which is contacted by two ferromagnetic metals. In the\npurely diffusive regime, the current may indeed be spin-polarized. However, for\na typical device geometry the degree of spin-polarization of the current is\nlimited to less than 0.1%, only. The change in device resistance for parallel\nand antiparallel magnetization of the contacts is up to quadratically smaller,\nand will thus be difficult to detect."
    },
    {
        "anchor": "Nonlinear anomalous Hall effect and negative magnetoresistance in a\n  system with random Rashba field: We predict two spin-dependent transport phenomena in two-dimensional electron\nsystems, which are induced by spatially fluctuating Rashba spin-orbit\ninteraction. When the electron gas is magnetized, the random Rashba interaction\nleads to the anomalous Hall effect. An example of such a system is a narrow-gap\nmagnetic semiconductor-based symmetric quantum well. We show that the anomalous\nHall conductivity reveals a strongly nonlinear dependence on the magnetization,\ndecreasing exponentially at large spin density. We also show that electron\nscattering from a fluctuating Rashba field in a two-dimensional nonmagnetic\nelectron system leads to a negative magnetoresistance arising solely due to\nspin-dependent effects.",
        "positive": "Magnetic vortices as localized mesoscopic domain wall pinning sites: We report on the controllable pinning of domain walls in stripes with\nperpendicular magnetic anisotropy by magnetostatic coupling to magnetic\nvortices in disks located above the stripe. Pinning mechanisms and depinning\nfields are reported. This novel pinning strategy, which can be realized by\ncurrent nanofabrication techniques, opens up new possibilities for the\nnon-destructive control of domain wall mobility in domain wall based spintronic\ndevices."
    },
    {
        "anchor": "Multi-band quantum ratchets: We investigate directed motion in non-adiabatically rocked ratchet systems\nsustaining few bands below the barrier. Upon restricting the dynamics to the\nlowest M bands, the total system-plus-bath Hamiltonian is mapped onto a\ndiscrete tight-binding model containing all the information both on the intra-\nand inter-well tunneling motion. A closed form for the current in the\nincoherent tunneling regime is obtained. In effective single-band ratchets, no\ncurrent rectification occurs. We apply our theory to describe rectification\neffects in vortex quantum ratchets devices. Current reversals upon variation of\nthe ac-field amplitude or frequency are predicted.",
        "positive": "Existence of nontrivial topologically protected states at grain\n  boundaries in bilayer graphene: signatures and electrical switching: Recent experiments [L. Ju et al., Nature, 2015, 520, 650] confirm the\nexistence of gapless states at domain walls created in gated bilayer graphene,\nwhen the sublattice stacking is changed from AB to BA. These states are\nsignificant because they are topologically protected, valley-polarized and give\nrise to conductance along the domain wall. Current theoretical models predict\nthe appearance of such states only at domain walls, which preserve the\nsublattice order. Here we show that the appearance of the topologically\nprotected states in stacking domain walls can be much more common in bilayer\ngraphene, since they can also emerge in unexpected geometries, e.g., at grain\nboundaries with atomic-scale topological defects. We focus on a bilayer system\nin which one of the layers contains a line of octagon-double pentagon defects,\nthat mix graphene sublattices. We demonstrate that gap states are preserved\neven with pentagonal defects. Remarkably, unlike previous predictions, the\nnumber of gap states changes by inverting the gate polarization, yielding an\nasymmetric conductance along the grain boundary under gate reversal. This\neffect, linked to defect states, should be detectable in transport measurements\nand could be exploited in electrical switches."
    },
    {
        "anchor": "Spaser chains: We show that depending on the values of the coupling constants, two different\nscenarios for the stationary behavior of a chain of interacting spasers may be\nrealized: (1) all the spasers are synchronized and oscillate with a unique\nphase and (2) a nonlinear autowave travels along the chain. In the latter\nscenario, the traveling wave is harmonic unlike excitations in other known\nnonlinear systems. The amplitude of this wave is determined by pumping and the\nwavenumber is determined by the coupling constants. Due to the nonlinear nature\nof the system, any initial distribution of spasers' states evolves into one of\nthese steady states.",
        "positive": "Quantum Hall Ferromagnets: Induced Topological term and electromagnetic\n  interactions: The $\\nu = 1$ quantum Hall ground state in materials like GaAs is well known\nto be ferromagnetic in nature. The exchange part of the Coulomb interaction\nprovides the necessary attractive force to align the electron spins\nspontaneously. The gapless Goldstone modes are the angular deviations of the\nmagnetisation vector from its fixed ground state orientation. Furthermore, the\nsystem is known to support electrically charged spin skyrmion configurations.\nIt has been claimed in the literature that these skyrmions are fermionic owing\nto an induced topological Hopf term in the effective action governing the\nGoldstone modes. However, objections have been raised against the method by\nwhich this term has been obtained from the microscopics of the system. In this\narticle, we use the technique of the derivative expansion to derive, in an\nunambiguous manner, the effective action of the angular degrees of freedom,\nincluding the Hopf term. Furthermore, we have coupled perturbative\nelectromagnetic fields to the microscopic fermionic system in order to study\ntheir effect on the spin excitations. We have obtained an elegant expression\nfor the electromagnetic coupling of the angular variables describing these spin\nexcitations."
    },
    {
        "anchor": "Exciton Mott transition in Si Revealed by Terahertz Spectroscopy: Exciton Mott transition in Si is investigated by using terahertz time-domain\nspectroscopy. The excitonic correlation as manifested by the 1s-2p resonance is\nobserved above the Mott density. The scattering rate of charge carriers is\nprominently enhanced at the proximity of Mott density, which is attributed to\nthe non-vanishing exciton correlation in the metallic electron-hole plasma.\nConcomitantly, the signature of plasmon-exciton coupling is observed in the\nloss function spectra.",
        "positive": "Microscopic polarization and magnetization fields in extended systems: We introduce microscopic polarization and magnetization fields at each site\nof an extended system, as well as free charge and current density fields\nassociated with charge movement from site to site, by employing a lattice gauge\napproach based on a set of orthogonal orbitals associated with each site. These\nmicroscopic fields are defined using a single-particle electron Green function,\nand the equations governing its evolution under excitation by an\nelectromagnetic field at arbitrary frequency involve the electric and magnetic\nfields rather than the scalar and vector potentials. If the sites are taken to\nbe far from each other, we recover the limit of isolated atoms. For an infinite\ncrystal we choose the orbitals to be maximally-localized Wannier functions, and\nin the long wavelength limit we recover the expected linear response of an\ninsulator, including the zero frequency transverse conductivity of a\ntopologically nontrivial insulator. For a topologically trivial insulator we\nrecover the expected expressions for the macroscopic polarization and\nmagnetization in the ground state, and find that the linear response to\nexcitation at arbitrary frequency is described solely by the microscopic\npolarization and magnetization fields. For very general optical response\ncalculations the microscopic fields necessarily satisfy charge conservation,\neven under basis truncation, and do not suffer from the false divergences at\nzero frequency that can plague response calculations using other approaches."
    },
    {
        "anchor": "Full Counting Statistics and Field Theory: We review the relations between the full counting statistics and the field\ntheory of electric circuits. We demonstrate that for large conductances the\ncounting statistics is determined by non-trivial saddle-point of the field.\nCoulomb effects in this limit are presented as quantum corrections that can\nstongly renormalize the action at low energies.",
        "positive": "Origin of Lattice Spin in Graphitic Systems: Lattice spin, in planar condensed matter system with emergent Dirac\ndispersion, is shown to emerge from the inherent SU(2) symmetry, arising\nthrough Schwingers angular momentum construction from anti-commuting Heisenberg\noperators of the sub-lattices. The presence of a mass term in the emergent\nDirac dispersion is essential for the existence of this spin. The usual hopping\nterm, that entangles the two sub-lattices, leads to the orbital counterpart.\nRelative sub-lattice displacements, that couple to the effective Dirac fermions\nlike U(1) gauge fields, do not effect the lattice spin."
    },
    {
        "anchor": "Honeycomb lattice of graphite probed by scanning tunneling microscopy\n  with a carbon nanotube tip: A carbon nanotube (CNT) tip was fabricated at the apex of an etched tungsten\nwire by chemical vapor deposition and used for scanning tunneling microscopy.\nThe honeycomb lattice of graphite in the STM images was resolved with a CNT tip\nat T=79 K. The superior spatial resolution originating from the p orbitals of a\nCNT is responsible for the image of the honeycomb lattice of graphite in the\nSTM images. The CNT tips are useful to image samples whose lattice constants\nare small and to get orbital information in samples with orbital ordering due\nto their superior spatial resolution with the sharp p orbitals.",
        "positive": "Channel Blockade in a Two-Path Triple-Quantum-Dot System: Electronic transport through a two-path triple-quantum-dot system with two\nsource leads and one drain is studied. By separating the conductance of the two\ndouble dot paths, we are able to observe double dot and triple dot physics in\ntransport and study the interaction between the paths. We observe channel\nblockade as a result of inter-channel Coulomb interaction. The experimental\nresults are understood with the help of a theoretical model which calculates\nthe parameters of the system, the stability regions of each state and the full\ndynamical transport in the triple dot resonances."
    },
    {
        "anchor": "Rashba-induced transverse pure spin currents in a four-terminal quantum\n  dot ring: By applying a local Rashba spin-orbit interaction on an individual quantum\ndot of a four-terminal four-quantum-dot ring and introducing a finite bias\nbetween the longitudinal terminals, we theoretically investigate the charge and\nspin currents in the transverse terminals. It is found that when the quantum\ndot levels are separate from the chemical potentials of the transverse\nterminals, notable pure spin currents appear in the transverse terminals with\nthe same amplitude and opposite polarization directions. Besides, the\npolarization directions of such pure spin currents can be inverted by altering\nstructure parameters, i.e., the magnetic flux, the bias voltage, and the values\nof quantum dot levels with respect to the chemical potentials of the transverse\nterminals.",
        "positive": "Arrayed van der Waals Vertical Heterostructures based on 2D GaSe Grown\n  by Molecular Beam Epitaxy: Vertically stacking two dimensional (2D) materials can enable the design of\nnovel electronic and optoelectronic devices and realize complex functionality.\nHowever, the fabrication of such artificial heterostructures in wafer scale\nwith an atomically-sharp interface poses an unprecedented challenge. Here, we\ndemonstrate a convenient and controllable approach for the production of\nwafer-scale 2D GaSe thin films by molecular beam epitaxy. In-situ reflection\nhigh-energy electron diffraction oscillations and Raman spectroscopy reveal a\nlayer-by-layer van der Waals epitaxial growth mode. Highly-efficient\nphotodetector arrays were fabricated based on few-layer GaSe on Si. These\nphotodiodes show steady rectifying characteristics and a relatively high\nexternal quantum efficiency of 23.6%. The resultant photoresponse is super-fast\nand robust with a response time of 60 us. Importantly, the device shows no sign\nof degradation after 1 million cycles of operation. Our study establishes a new\napproach to produce controllable, robust and large-area 2D heterostructures and\npresents a crucial step for further practical applications."
    },
    {
        "anchor": "Universal Symmetry-Protected Resonances in a Spinful Luttinger Liquid: We study the problem of resonant tunneling through a quantum dot in a spinful\nLuttinger liquid. For a range of repulsive interactions, we find that for\nsymmetric barriers there exist resonances with a universal peak conductance\n$2g^* e^2/h$ that are controlled by a non-trivial intermediate fixed point.\nThis fixed point is also a quantum critical point separating symmetry-protected\ntopological phases. By tuning the system through resonance, all SPT phases can\nbe accessed. For a particular interaction strength with Luttinger parameters\n$g_\\rho=1/3$ and $g_\\sigma=1$, we show that the problem is equivalent to a two\nchannel $SU(3)$ Kondo problem($SU(3)_2$ CFT). At the Toulouse limit, both\nproblems can be mapped to a quantum Brownian motion model on a Kagome lattice,\nwhich in turn is related to the quantum Brownian motion on a honeycomb lattice\nand the three-channel $SU(2)$ Kondo problem($SU(2)_3$ CFT). \"Level-rank\nduality\" in the quantum Brownian motion model relating $SU(2)_k$ CFT to\n$SU(k)_2$ CFT is also explored. Utilizing the boundary conformal field theory,\nthe on-resonance conductance of our resonant tunneling problem is calculated as\nwell as the scaling dimension of the leading relevant operator. This allows us\nto compute the scaling behavior of the resonance line-shape as a function of\ntemperature.",
        "positive": "Frequency Multiplexing for Readout of Spin Qubits: We demonstrate a low loss, chip-level frequency multiplexing scheme for\nreadout of scaled-up spin qubit devices. By integrating separate bias tees and\nresonator circuits on-chip for each readout channel, we realize dispersive\ngate-sensing in combination with charge detection based on two rf quantum point\ncontacts (rf-QPCs). We apply this approach to perform multiplexed readout of a\ndouble quantum dot in the few-electron regime, and further demonstrate\noperation of a 10-channel multiplexing device. Limitations for scaling spin\nqubit readout to large numbers of multiplexed channels is discussed."
    },
    {
        "anchor": "Magneto-electronic properties of multilayer black phosphorus: We examine the electronic properties of 2D electron gas in black phosphorus\nmultilayers in the presence of a perpendicular magnetic field, highlighting the\nrole of in-plane anisotropy on various experimental quantities such as ac\nmagneto-conductivity, screening, and magneto-plasmons. We find that resonant\nstructures in the ac conductivity exhibits a red-shift with increasing doping\ndue to inter-band coupling, $\\gamma$. This arises from an extra correction term\nin the Landau energy spectrum proportional to $n^2\\gamma^2$ ($n$ is Landau\nindex), up to second order in $\\gamma$. We found also that Coulomb interaction\nleads to highly anisotropic magneto-excitons.",
        "positive": "Cerenkov generation of high-frequency confined acoustic phonons in\n  quantum wells: We analyze the Cerenkov emission of high-frequency confined acoustic phonons\nby drifting electrons in a quantum well. We find that the electron drift can\ncause strong phonon amplification (generation). A general formula for the gain\ncoefficient, alpha, is obtained as a function of the phonon frequency and the\nstructure parameters. The gain coefficient increases sharply in the short-wave\nregion. For the example of a Si/SiGe/Si device it is shown that the\namplification coefficients of the order of hundreds of 1/cm can be achieved in\nthe sub-THz frequency range."
    },
    {
        "anchor": "Weyl points and topological surface states in a three-dimensional\n  elastic lattice: Following the realization of Weyl semimetals in quantum electronic materials,\nclassical wave analogues of Weyl materials have also been theorized and\nexperimentally demonstrated in photonics and acoustics. Weyl points in elastic\nsystems, however, have been a much more recent discovery. In this study, we\nreport on the design of an elastic fully-continuum three-dimensional material\nthat, while offering structural and load-bearing functionalities, is also\ncapable of Weyl degeneracies and surface topologically-protected modes in a way\ncompletely analogous to the quantum mechanical counterpart. The topological\ncharacteristics of the lattice are obtained by \\textit{ab initio} numerical\ncalculations without employing any further simplifications. The results clearly\ncharacterize the topological structure of the Weyl points and are in full\nagreement with the expectations of surface topological modes. Finally, full\nfield numerical simulations are used to confirm the existence of surface states\nand to illustrate their extreme robustness towards lattice disorder and\ndefects.",
        "positive": "Topological crystalline insulator phase in graphene multilayers: While the experimental progress on three dimensional topological insulators\nis rapid, the development of their two dimensional counterparts has been\ncomparatively slow, despite their technological promise. The main reason is\nmaterials challenges of the to date only realizations of two-dimensional\ntopological insulators, in semiconductor quantum wells. Here we identify a two\ndimensional topological insulator in a material which does not face similar\nchallenges and which is by now most widely available and well-charaterized:\ngraphene. For certain commensurate interlayer twists graphene multilayers are\ninsulators with sizable bandgaps. We show that they are moreover in a\ntopological phase protected by crystal symmetry. As its fundamental signature,\nthis topological state supports one-dimensional boundary modes. They form\nlow-dissipation quantum wires that can be defined purely electrostatically."
    },
    {
        "anchor": "Floquet topological insulator phase in a Weyl semimetal thin film with\n  disorder: We investigate the effects of periodic fields and disorder on topological\nproperties of a Weyl-semimetal thin film. The two periodic fields, i.e., a\nperiodic magnetic field and elliptically polarized light, are discussed\nrespectively. By use of the Floquet theory, we find that both the two periodic\ndrives can resonantly induce the topological transitions from normal insulator\n(NI) phases to Floquet topological insulator (FTI) phases. The Floquet\ntopological transitions are characterized by variation of Chern number.\nMoreover, we show that the Floquet topological transitions can be explained by\na combination of the quantum well approximation and the rotating wave\napproximation. In the disordered Weyl-semimetal thin film model under periodic\nfields, we calculate the Bott index to characterize topological phase. It is\nfound that the FTI phase is robust against weak disorder, and collapses for\nstrong disorder strength. Interestingly, we find that disorder can also induce\na topological transition from a topological trivial phase to an FTI phase,\nestablishing the Floquet topological Anderson insulator (FTAI) phase. Finally,\nan effective-medium theory based on the Born approximation further confirms the\nnumerical conclusions.",
        "positive": "Waiting time distributions in a two-level fluctuator coupled to a\n  superconducting charge detector: We analyze charge fluctuations in a parasitic state strongly coupled to a\nsuperconducting Josephson-junction-based charge detector. The charge dynamics\nof the state resembles that of electron transport in a quantum dot with two\ncharge states, and hence we refer to it as a two-level fluctuator. By\nconstructing the distribution of waiting times from the measured detector\nsignal and comparing it with a waiting time theory, we extract the electron in-\nand out-tunneling rates for the two-level fluctuator, which are severely\nasymmetric."
    },
    {
        "anchor": "Correlated magnetic states in domain and grain boundaries in graphene: Ab initio calculations indicate that while the electronic states introduced\nby grain boundaries in graphene are only partially confined to the defect core,\na domain boundary introduces states near the Fermi level that are very strongly\nconfined to the core of the defect, and that display a ferromagnetic ground\nstate. The domain boundary is fully immersed within the graphene matrix, hence\nthis magnetic state is protected from reconstruction effects that have hampered\nexperimental detection in the case of ribbon edge states. Furthermore, our\ncalculations suggest that charge transfer between one-dimensional extended\ndefects and the bulk in graphene is short ranged for both grain and domain\nboundaries.",
        "positive": "Plasmonic Dirac Cone in Twisted Bilayer Graphene: We discuss plasmons of biased twisted bilayer graphene when the Fermi level\nlies inside the gap. The collective excitations are a network of chiral edge\nplasmons (CEP) entirely composed of excitations in the topological electronic\nedge states (EES) that appear at the AB-BA interfaces. The CEP form an\nhexagonal network with an unique energy scale\n$\\epsilon_p=\\frac{e^2}{\\epsilon_0\\epsilon t_0}$ with $t_0$ the moir\\'e lattice\nconstant and $\\epsilon$ the dielectric constant. From the dielectric matrix we\nobtain the plasmon spectra that has two main characteristics: (i) a diverging\ndensity of states at zero energy, and (ii) the presence of a plasmonic Dirac\ncone at $\\hbar\\omega\\sim\\epsilon_p/2$ with sound velocity $v_D=0.0075c$, which\nis formed by zigzag and armchair current oscillations. A network model reveals\nthat the antisymmetry of the plasmon bands implies that CEP scatter at the\nhexagon vertices maximally in the deflected chiral outgoing directions, with a\ncurrent ratio of 4/9 into each of the deflected directions and 1/9 into the\nforward one. We show that scanning near-field microscopy should be able to\nobserve the predicted plasmonic Dirac cone and its broken symmetry phases."
    },
    {
        "anchor": "Hinge Spin Polarization in Magnetic Topological Insulators Revealed by\n  Resistance Switch: We report on the possibility to detect hinge spin polarization in magnetic\ntopological insulators by resistance measurements. By implementing a\nthree-dimensional model of magnetic topological insulators into a\nmulti-terminal device with ferromagnetic contacts near the top surface, local\nspin features of the chiral edge modes are unveiled. We find local spin\npolarization at the hinges that inverts sign between top and bottom surfaces.\nAt the opposite edge, the topological state with inverted spin polarization\npropagates in the reverse direction. Large resistance switch between forward\nand backward propagating states is obtained, driven by the matching between the\nspin polarized hinges and the ferromagnetic contacts. This feature is general\nto the ferromagnetic, antiferromagnetic and canted-antiferromagnetic phases,\nand enables the design of spin-sensitive devices, with the possibility of\nreversing the hinge spin polarization of the currents.",
        "positive": "Spin-coupled double-quantum-dot behavior inside a single-molecule\n  transistor: We report on the observation of Kondo and split Kondo peaks in\nsingle-molecule transistors containing a single spin transition molecule with a\nFe2+ ion. Coulomb blockade characteristics reveal a double quantum dot behavior\nin a parallel configuration, making our system a molecular equivalent to a\nsemiconducting double-quantum-dot system. As the gate voltage is increased the\ncharging of the second dot by an additional electron induces a splitting of the\nKondo peak. We discuss possible origins of this effect including a spin\ntransition into a high-spin state."
    },
    {
        "anchor": "Kondo effects in a triangular triple quantum dot: NRG study in the whole\n  region of the electron filling: We study the low-energy properties of a triangular triple quantum dot\nconnected to two non-interacting leads in a wide parameter range, using the\nnumerical renormalization group (NRG). Various kinds of Kondo effects take\nplace in this system depending on the electron filling N_{tot}, or the level\nposition $\\epsilon_d$ of the triple dot. The SU(4) Kondo behavior is seen in\nthe half-filled case N_{tot} = 3.0 at the dip of the series conductance, and it\ncauses a charge redistribution between the even and odd orbitals in the\ntriangle. We show generally that the quasi-particle excitations from a local\nFermi-liquid ground state acquire a channel symmetry at zero points of the\ntwo-terminal conductance, in the case the system has time-reversal and\ninversion symmetries. It causes the SU(4) behavior at low energies, while the\norbital degeneracy in the triangle determines the high-energy behavior. At\nfour-electron filling N_{tot} = 4.0, a local S=1 moment emerges at high\ntemperatures due to a Nagaoka ferromagnetic mechanism. It is fully screened by\nthe electrons from the two conducting channels via a two-stage Kondo effect,\nwhich is caused by a difference in the charge distribution in the even and odd\norbitals.",
        "positive": "Decoherence induced by an ordered environment: This Letter deals with the time evolution of a qubit weakly coupled to a\nreservoir which has a symmetry broken state with long range order at finite\ntemperatures. In particular, we model the ordered reservoir by a standard BCS\nsuperconductor with s-wave pairing. We study the reduced density matrix of a\nqubit using both the time-convolutionless and Nakajima-Zwanzig approximations.\nWe study different kinds of couplings between the qubit and the superconducting\nbath. We find that ordering in the superconducting bath generically leads to an\nunfavorable non- Markovian faster-than-exponential decay of the qubit\ncoherence. On the other hand, a coupling of the qubit to the non-ordered sector\nof the bath can result in a Markovian decoherence of the qubit with a drastic\nreduction of the decoherence rate. Since these behaviors are endemic to the\nordered phase, qubits can serve as useful probes of continuous phase\ntransitions in their environment. We also briefly discuss the validity of our\nmain result, faster than exponential decay of the qubit coherences, for a qubit\ncoupled to a generic ordered bath with a spontaneously broken continuous\nsymmetry at finite temperatures."
    },
    {
        "anchor": "Current-Driven Dynamics of Frustrated Skyrmions in a Synthetic\n  Antiferromagnetic Bilayer: We report the current-driven dynamics of frustrated skyrmions in an\nantiferromagnetically exchange coupled bilayer system, where the bilayer\nskyrmion consists of two monolayer skyrmions with opposite skyrmion numbers\n$Q$. We show that the in-plane current-driven bilayer skyrmion moves in a\nstraight path, while the out-of-plane current-driven bilayer skyrmion moves in\na circular path. It is found that the in-plane current-driven mobility of a\nbilayer skyrmion is much better than the monolayer one at a large ratio of\n$\\beta/\\alpha$, where $\\alpha$ and $\\beta$ denote the damping parameter and\nnon-adiabatic spin transfer torque strength, respectively. Besides, the\nout-of-plane current-driven mobility of a bilayer skyrmion is much better than\nthe monolayer one when $\\alpha$ is small. We also reveal that one bilayer\nskyrmion (consisting of monolayer skyrmions with $Q=\\pm 2$) can be separated to\ntwo bilayer skyrmions (consisting of monolayer skyrmions with $Q=\\pm 1$) driven\nby an out-of-plane current. Our results may be useful for designing skyrmionic\ndevices based on frustrated multilayer magnets.",
        "positive": "Unconventional superconducting states of interlayer pairing in bilayer\n  and trilayer graphene: We develop a theory for interlayer pairing of chiral electrons in graphene\nmaterials which results in an unconventional superconducting (S) state with\ns-wave spin-triplet order parameter. In a pure bilayer graphene, this\nsuperconductivity exhibits a gapless property with an exotic effect of\ntemperature-induced condensation causing an increase of the pairing amplitude\n(PA) with increasing temperature. We find that a finite doping opens a gap in\nthe excitation spectrum and weakens this anomalous temperature-dependence. We\nfurther explore the possibility of realizing variety of pairing patterns with\ndifferent topologies of the Fermi surface, by tuning the difference in the\ndoping of the two layers. In trillayer graphene, the interlayer\nsuperconductivity is characterized by a two components order parameter which\ncan be used to define two distinct phases in which only one of the components\nis non vanishing. For ABA stacking the stable state is determined by a\ncompetition between these two phases. By varying the relative amplitude of the\ncorresponding coupling strenghes, a first order phase transition can occur\nbetween these two phases. For ABC stacking, we find that the two phases coexist\nwith a possibility of a similar phase transition which turns out to be second\norder."
    },
    {
        "anchor": "Detection of 2D electron g-factor sign inversion in narrow GaAs/AlGaAs\n  quantum wells: By means of CW polarization-resolved photoluminescence spectroscopy we\ndemonstrate the sign inversion of $g_z$-component of 2D electron g-factor with\nnarrowing of a hosting GaAs/Al$_{0.33}$Ga$_{0.67}$As quantum well (QW). The\nenergy splitting between spectral lines correspoding to recombination from the\nelectron lowest Landau level and possessing opposite curcular polarization is\nanalyzed. Due to exchange interaction, this value reveals maximum or minimum as\na function of magnetic field strength in the vicinity of electron filling\nfactor $\\nu=3$. The actual type of extremum depends on the electron\n$g_z$-component sign. The method allows to detect the sign inversion of\nelectron Lande g-factor with its absolute value changing by less than $\\Delta g\n\\approx 0.06$. The reversal happens at a QW width of ($65\\pm 3$ \\AA).",
        "positive": "Spin-orbit enabled quantum transport channels in a two-hole double\n  quantum dot: We analyze experimentally and theoretically the transport spectra of a gated\nlateral GaAs double quantum dot containing two holes. The strong spin-orbit\ninteraction present in the hole subband lifts the Pauli spin blockade and\nallows to map out the complete spectra of the two-hole system. By performing\nmeasurements in both source-drain voltage directions, at different detunings\nand magnetic fields, we carry out quantitative fitting to a Hubbard two-site\nmodel accounting for the tunnel coupling to the leads and the spin-flip\nrelaxation process. We extract the singlet-triplet gap and the magnetic field\ncorresponding to the singlet-triplet transition in the double-hole ground\nstate. Additionally, at the singlet-triplet transition we find a resonant\nenhancement (in the blockaded direction) and suppression of current (in the\nconduction direction). The current enhancement stems from the multiple\nresonance of two-hole levels, opening several conduction channels at once. The\ncurrent suppression arises from the quantum interference of spin-conserving and\nspin flipping tunneling processes."
    },
    {
        "anchor": "Moir\u00e9 Modulated Lattice Strain and Thickness-Dependent Lattice\n  Expansion in Epitaxial Ultrathin Films of PdTe$_2$: We report the epitaxial growth of PdTe$_2$ ultrathin films on topological\ninsulator Bi$_2$Se$_3$. A prominent Moir\\'e pattern was observed in STM\nmeasurements. The Moir\\'e periodicity increases as film thickness decreases,\nindicating a lattice expansion of epitaxial PdTe$_2$ thin films with lower\nthicknesses. In addition, our simulations based on Moir\\'e Metrology reveal\nuniaxial lattice strains at the edge of PdTe$_2$ domains, and anisotropic\nstrain distributions throughout the Moir\\'e supercell with a net change in\nlattice strain up to ~2.9%. Our DFT calculations show that this strain effect\nleads to a narrowing of the band gap at $\\Gamma$ point near the Fermi level.\nUnder a strain of ~2.8%, the band gap at $\\Gamma$ closes completely. Further\nincreasing the lattice strain makes the band gap reopen and the order of\nconduction band and valence bands inverted in energy. The results offer a proof\nof concept for constructing quantum grids of topological materials under the\nmodulation of Moir\\'e potentials.",
        "positive": "Deterministic and stochastic aspects of current-induced magnetization\n  reversal in perpendicular nanomagnets: We study the incubation and transition times that characterize the\nmagnetization switching induced by spin-orbit torques in nanomagnets with\nperpendicular anisotropy. We present a phenomenological model to interpret the\ndependence of the incubation time on the amplitude of the voltage pulse and\nassisting magnetic field and estimate the volume of the seed domain that\ntriggers the switching. Our measurements evidence a correlation between the\nincubation and transition times that is mediated by the temperature variation\nduring the electric pulse. In addition, we discuss the stochastic distributions\nof the two times in terms of the energy barriers opposing the nucleation and\nexpansion of the seed domain. We propose two models based on the log-normal and\ngamma functions to account for the different origin of the variability of the\nincubation and transition times, which are associated with a single nucleation\nbarrier and multiple pinning sites, respectively."
    },
    {
        "anchor": "Fano-Andreev effect in a T-shaped Double Quantum Dot in the Coulomb\n  blockade regime: We studied the effects of superconducting quantum correlations in a system\nconsisting of two quantum dots, two normal leads, and a superconductor. Using\nthe non-equilibrium Green's functions method, we analyzed the transmission,\ndensity of states, and differential conductance of electrons between the normal\nleads. We found that the superconducting correlations resulted in Fano-Andreev\ninterference, which is characterized by two anti-resonance line shapes in all\nof these quantities. This behavior was observed in both equilibrium and\nnon-equilibrium regimes and persisted even when Coulomb correlations were taken\ninto account using the Hubbard-I approximation. It is worth noting that the\nrobustness of this behavior against these conditions has not been studied\npreviously in the literature.",
        "positive": "Electrical probing of the spin conductance of mesoscopic cavities: We investigate spin-dependent transport in three--terminal mesoscopic\ncavities with spin--orbit coupling. Focusing on the inverse spin Hall effect,\nwe show how injecting a pure spin current or a polarized current from one\nterminal generates additional charge current and/or voltage across the two\noutput terminals. This allows to extract the spin conductance of the cavity\nfrom two purely electrical measurements on the output. We use random matrix\ntheory to show that the spin conductance of chaotic ballistic cavities\nfluctuates universally about zero mesoscopic average and describe experimental\nimplementations of mesoscopic spin to charge current converters."
    },
    {
        "anchor": "Microscopic description of intraband absorption in graphene: the\n  occurrence of transient negative differential transmission: We present a microscopic explanation of the controversially discussed\ntransient negative differential transmission observed in degenerate optical\npump-probe measurements in graphene. Our approach is based on the density\nmatrix formalism allowing a time- and momentum-resolved study of carrier-light,\ncarrier-carrier, and carrier-phonon interaction on microscopic footing. We show\nthat phonon-assisted optical intraband transitions give rise to transient\nabsorption in the optically excited hot carrier system counteracting pure\nabsorption bleaching of interband transitions. While interband transition\nbleaching is relevant in the first hundreds of fs after the excitation,\nintraband absorption sets in at later times. In particular, in the low\nexcitation regime, these intraband absorption processes prevail over the\nabsorption bleaching resulting in a zero-crossing of the differential\ntransmission. Our findings are in good agreement with recent experimental\npump-probe studies.",
        "positive": "Commensurate-incommensurate phase transition in bilayer graphene: A commensurate-incommensurate phase transition in bilayer graphene is\ninvestigated in the framework of the Frenkel-Kontorova model extended to the\ncase of two interacting chains of particles. Analytic expressions are derived\nto estimate the critical unit elongation of one of the graphene layers at which\nthe transition to the incommensurate phase takes place, the length and\nformation energy of incommensurability defects (IDs) and the threshold force\nrequired to start relative motion of the layers on the basis of\ndispersion-corrected density functional theory calculations of the interlayer\ninteraction energy as a function of the relative position of the layers. These\nestimates are confirmed by atomistic calculations using the DFT-D based\nclassical potential. The possibility to measure the barriers for relative\nmotion of graphene layers by the study of formation of IDs in bilayer graphene\nis discussed."
    },
    {
        "anchor": "Atomistic simulation of finite temperature magnetism of nanoparticles:\n  application to cobalt clusters on Au(111): We developed a technique to determine suitable spin models for small embedded\nclusters of arbitrary geometry by combining the spin-cluster expansion with the\nrelativistic disordered local moment scheme. We present results for uncovered\nand covered hexagonal Co clusters on Au(111) surface, and use classical Monte\nCarlo simulations to study the temperature dependent properties of the systems.\nTo test the new method we compare the calculated spin-model parameters of the\nuncovered clusters with those of a Co monolayer deposited on Au(111). In\ngeneral, the isotropic and DM interactions are larger between atoms at the\nperimeter than at the center of the clusters. For Co clusters covered by Au,\nboth the contribution to the magnetic anisotropy and the easy axis direction of\nthe perimeter atoms differ from those of the inner atoms due to reduced\nsymmetry. We investigate the spin reversals of the covered clusters with\nperpendicular magnetic anisotropy and by measuring the magnetization variance\nin the easy direction we suggest a technique to determine the blocking\ntemperature of superparamagnetic particles. We also determine the N\\'eel\nrelaxation time from the Monte Carlo simulations and find that it satisfies the\nN\\'eel--Arrhenius law with an energy barrier close to the magnetic anisotropy\nenergy of the clusters.",
        "positive": "Valley Dynamics of Excitons in Monolayer Dichalcogenides: Monolayer transition-metal dichalcogenides (TMDCs) have recently emerged as\npossible candidates for valleytronic applications, as the spin and valley\npseudospin are directly coupled and stabilized by a large spin splitting. In\nthese semiconducting materials, optically excited electron-hole pairs form\ntightly Coulomb-bound excitons with large binding energies. The selection rules\nfor excitonic transitions allow for direct optical generation of a\nvalley-polarized exciton population using resonant excitation. Here, we\ninvestigate the exciton valley dynamics in monolayers of three different TMDCs\nby means of time-resolved Kerr rotation at low temperatures. We observe\npronounced differences in the valley dynamics of tungsten- and molybdenum-based\nTMDCs, which are directly related to the opposite order of the conduction-band\nspin splitting in these materials."
    },
    {
        "anchor": "Exploring the Way to Approach the Efficiency Limit of Perovskite Solar\n  Cells by Drift-Diffusion Model: Drift-diffusion model is an indispensable modeling tool to understand the\ncarrier dynamics (transport, recombination, and collection) and simulate\npractical-efficiency of solar cells (SCs) through taking into account various\ncarrier recombination losses existing in multilayered device structures.\nExploring the way to predict and approach the SC efficiency limit by using the\ndrift-diffusion model will enable us to gain more physical insights and design\nguidelines for emerging photovoltaics, particularly perovskite solar cells. Our\nwork finds out that two procedures are the prerequisites for predicting and\napproaching the SC efficiency limit. Firstly, the intrinsic radiative\nrecombination needs to be corrected after adopting optical designs which will\nsignificantly affect the open-circuit voltage at its Shockley-Queisser limit.\nThrough considering a detailed balance between emission and absorption of\nsemiconductor materials at the thermal equilibrium, and the Boltzmann\nstatistics at the non-equilibrium, we offer a different approach to derive the\naccurate expression of intrinsic radiative recombination with the optical\ncorrections for semiconductor materials. The new expression captures light\ntrapping of the absorbed photons and angular restriction of the emitted photons\nsimultaneously, which are ignored in the traditional Roosbroeck-Shockley\nexpression. Secondly, the contact characteristics of the electrodes need to be\ncarefully engineered to eliminate the charge accumulation and surface\nrecombination at the electrodes. The selective contact or blocking layer\nincorporated nonselective contact that inhibits the surface recombination at\nthe electrode is another important prerequisite. With the two procedures, the\naccurate prediction of efficiency limit and precise evaluation of efficiency\ndegradation for perovskite solar cells are attainable by the drift-diffusion\nmodel.",
        "positive": "Universal conductance fluctuations in a MnBi$_2$Te$_4$ thin film: Quantum coherence of electrons can produce striking behaviors in mesoscopic\nconductors, including weak localization and the Aharonov-Bohm effect. Although\nmagnetic order can also strongly affect transport, the combination of coherence\nand magnetic order has been largely unexplored. Here, we examine quantum\ncoherence-driven universal conductance fluctuations in the antiferromagnetic,\ncanted antiferromagnetic, and ferromagnetic phases of a thin film of the\ntopological material MnBi$_2$Te$_4$. In each magnetic phase we extract a charge\ncarrier phase coherence length of about 100 nm. The conductance\nmagnetofingerprint is repeatable when sweeping applied magnetic field within\none magnetic phase, but changes when the applied magnetic field crosses the\nantiferromagnetic/canted antiferromagnetic magnetic phase boundary.\nSurprisingly, in the antiferromagnetic and canted antiferromagnetic phase, but\nnot in the ferromagnetic phase, the magnetofingerprint depends on the direction\nof the field sweep. To explain these observations, we suggest that conductance\nfluctuation measurements are sensitive to the motion and nucleation of magnetic\ndomain walls in MnBi$_2$Te$_4$."
    },
    {
        "anchor": "Supercurrent Reversal in Two-Dimensional Topological Insulators: We calculate supercurrent across a two-dimensional topological insulator\nsubjected to an external magnetic field. When the edge states of a narrow\ntwo-dimensional topological insulator are hybridized, an external magnetic\nfield can close the hybridization gap, thus driving a quantum phase transition\nfrom insulator to semimetal states of the topological insulator. We find a sign\nreversal of the supercurrent at the quantum phase transition revealing\nintrinsic properties of topological insulators via Josephson effect.",
        "positive": "Nanoassembly of Polydisperse Photonic Crystals based on Binary and\n  Ternary Polymer Opal Alloys: Ordered binary and ternary photonic crystals, composed of different sized\npolymer-composite spheres with diameter ratios up to 120%, are generated using\nbending induced oscillatory shearing (BIOS). This viscoelastic system creates\npolydisperse equilibrium structures, producing mixed opaline colored films with\ngreatly reduced requirements for particle monodispersity, and very different\nsphere size ratios, compared to other methods of nano-assembly."
    },
    {
        "anchor": "Image effects in transport at metal-molecule interfaces: We present a method for incorporating image-charge effects into the\ndescription of charge transport through molecular devices. A simple model\nallows us to calculate the adjustment of the transport levels, due to the\npolarization of the electrodes as charge is added to and removed from the\nmolecule. For this, we use the charge distributions of the molecule between two\nmetal electrodes in several charge states, rather than in gas phase, as\nobtained from a density-functional theory-based transport code. This enables us\nto efficiently model level shifts and gap renormalization caused by\nimage-charge effects, which are essential for understanding molecular transport\nexperiments. We apply the method to benzene di-amine molecules and compare our\nresults with the standard approach based on gas phase charges. Finally, we give\na detailed account of the application of our approach to porphyrin-derivative\ndevices recently studied experimentally by Perrin et al. [Nat. Nanotechnol. 8,\n282 (2013)], which demonstrates the importance of accounting for image-charge\neffects when modeling transport through molecular junctions.",
        "positive": "Resistively Detected NMR in Quantum Hall States: Investigation of the\n  anomalous lineshape near $\u03bd=1$: A study of the resistively detected nuclear magnetic resonance (RDNMR)\nlineshape in the vicinity of $\\nu=1$ was performed on a high-mobility 2D\nelectron gas formed in GaAs/AlGaAs. In higher Landau levels, application of an\nRF field at the nuclear magnetic resonance frequency coincides with an observed\nminimum in the longitudinal resistance, as predicted by the simple hyperfine\ninteraction picture. Near $\\nu=1$ however, an anomalous dispersive lineshape is\nobserved where a resistance peak follows the usual minimum. In an effort to\nunderstand the origin of this anomalous peak we have studied the resonance\nunder various RF and sample conditions. Interestingly, we show that the\nlineshape can be completely inverted by simply applying a DC current. We\ninterpret this as evidence that the minima and maxima in the lineshape\noriginate from two distinct mechanisms."
    },
    {
        "anchor": "Mapping the chemical potential dependence of current-induced spin\n  polarization in a topological insulator: We report electrical measurements of the current-induced spin polarization of\nthe surface current in topological insulator devices where contributions from\nbulk and surface conduction can be disen- tangled by electrical gating. The\ndevices use a ferromagnetic tunnel junction (permalloy/Al2O3) as a spin\ndetector on a back-gated (Bi,Sb)2Te3 channel. We observe hysteretic voltage\nsignals as the magnetization of the detector ferromagnet is switched parallel\nor anti-parallel to the spin polariza- tion of the surface current. The\namplitude of the detected voltage change is linearly proportional to the\napplied DC bias current in the (Bi,Sb)2Te3 channel. As the chemical potential\nis tuned from the bulk bands into the surface state band, we observe an\nenhancement of the spin-dependent voltages up to 300% within the range of the\nelectrostatic gating. Using a simple model, we extract the spin polarization\nnear charge neutrality (i.e. the Dirac point).",
        "positive": "Phonon-induced dephasing of chromium colour centres in diamond: We report on the coherence properties of single photons from chromium-based\ncolour centres in diamond. We use field-correlation and spectral lineshape\nmeasurements to reveal the interplay between slow spectral wandering and fast\ndephasing mechanisms as a function of temperature. We show that the zero-phonon\ntransition frequency and its linewidth follow a power-law dependence on\ntemperature indicating that the dominant fast dephasing mechanisms for these\ncentres are direct electron-phonon coupling and phonon-modulated Coulomb\ncoupling to nearby impurities. Further, the observed reduction in the quantum\nyield for photon emission as a function of temperature is consistent with the\nopening of additional nonradiative channels through thermal activation to\nhigher energy states predominantly and indicates a near-unity quantum\nefficiency at 4 K."
    },
    {
        "anchor": "Domain Wall Motion in the Presence of Nuclear Spins: We investigate the motion of a domain wall in the presence of a dynamical\nhyperfine field. At temperature T high compared to the hyperfine coupling, the\nnuclear spins create a spatially random potential landscape, with dynamics\ndictated by the nuclear relaxation time $T_2$. The distribution of the domain\nwall relaxation times (both in the thermal and quantum regimes) can show a long\ntail, characteristic of stochastic processes where rare events are important.\nHere, these are due to occasional strong fluctuations in the nuclear spin\npolarisation.",
        "positive": "Programmable Mechanical Resonances in MEMS by Localized Joule Heating of\n  Phase Change Materials: A programmable micromechanical resonator based on a VO2 thin film is\nreported. Multiple mechanical eigenfrequency states are programmed using Joule\nheating as local power source, gradually driving the phase transition of VO2\naround its Metal-Insulator transition temperature. Phase coexistence of domains\nis used to tune the stiffness of the device via local control of internal\nstresses and mechanical properties. This study opens perspectives for\ndeveloping mechanically configurable nanostructure arrays."
    },
    {
        "anchor": "Transport signatures of superconducting hybrids with mixed singlet and\n  chiral triplet states: We propose a model for a superconductor where both spin-singlet and chiral\ntriplet pairing amplitudes can coexist. By solving the Bogoliubov-de Gennes\nequations with a general pair potential that accounts for both spin states we\nstudy experimental signatures of normal metal and superconductor hybrids. The\ninterplay between the spin-singlet and triplet correlations manifests in the\nappearance of two effective gaps. When the amplitude of the spin-triplet\ncomponent is stronger than that of the spin-singlet, a topological phase\ntransition into a non-trivial regime occurs. As a result, the normal\nmetal-superconductor conductance evolves from a conventional gap profile onto\nan unconventional zero-bias peak. Additionally, in the topologically\nnon-trivial phase, Andreev bound states formed at Josephson junctions present\nzero-energy modes; the number of those modes depends on the relative chirality\nof the junction. Finally, we present results for the current-phase relation and\nthe temperature dependence of the Josephson critical current within both\ntopological phases for several system parameters.",
        "positive": "Spin transistor operation driven by the Rashba spin-orbit coupling in\n  the gated nanowire: The theoretical description has been proposed for the operation of the spin\ntransistor in the gate-controlled InAs nanowire. The calculated current-voltage\ncharacteristics show that the current flowing from the source (spin injector)\nto the drain (spin detector) oscillates as a function of the gate voltage,\nwhich results from the precession of the electron spin caused by the Rashba\nspin-orbit interaction in the vicinity of the gate. We have studied two\noperation modes of the spin transistor: (A) the ideal operation mode with the\nfull spin polarization of electrons in the contacts, the zero temperature, and\nthe single conduction channel corresponding to the lowest-energy subband of the\ntransverse motion and (B) the more realistic operation mode with the partial\nspin polarization of the electrons in the contacts, the room temperature, and\nthe conduction via many transverse subbands taken into account. For mode (A)\nthe spin-polarized current can be switched on/off by the suitable tuning of the\ngate voltage, for mode (B) the current also exhibits the pronounced\noscillations but with no-zero minimal values. The computational results\nobtained for mode (B) have been compared with the recent experimental data and\na good agreement has been found."
    },
    {
        "anchor": "Anomalous magnetotransport through reflection-symmetric artificial\n  molecules: We calculate magnetotransport oscillations in current through a\ntriple-quantum-dot molecule, accounting for higher harmonics (having flux\nperiod h/ne, with n an integer). For a reflection-symmetric triple quantum dot,\nwe find that harmonics with n odd can dominate over those with n even. This is\nopposite to the behavior theoretically predicted due to `dark-state'\nlocalization, but has been observed in recent experiments [L. Gaudreau et al.,\nPhys. Rev. B, 80, 075415 (2009)], albeit in a triple-dot that may not exhibit\nreflection symmetry. This feature arises from a more general result: In the\nweak-coupling limit, we find that the current is flux-independent for an\narbitrary reflection-symmetric Aharonov-Bohm network. We further show that\nthese effects are observable in nanoscale systems even in the presence of\ntypical dephasing sources.",
        "positive": "Design of an efficient single photon source from a metallic nanorod\n  dimer: a quasinormal mode finite-difference time-domain approach: We describe how the finite-difference time-domain (FDTD) technique can be\nused to compute the quasinormal mode (QNM) for metallic nano-resonators, which\nis important for describing and understanding light-matter interactions in\nnanoplasmonics. We use the QNM to model the enhanced spontaneous emission rate\nfor dipole emitters near a gold nanorod dimer structure using a newly developed\nQNM expansion technique. Significant enhanced photon emission factors of around\n1500 are obtained with large output $\\beta$-factors of about $60\\%$."
    },
    {
        "anchor": "Spinless basis for spin-singlet FQH states: We investigate an alternative description of the SU(M)-singlet FQH state by\nusing the spinless basis. The SU(M)-singlet Halperin state is obtained via the\nq-deformation of the Laughlin state and its root of unity limit, by applying\nthe Yangian Gelfand-Zetlin basis for the spin Calogero-Sutherland model. The\nsqueezing rule for the SU(M) state is also investigated in terms of the\nspinless basis.",
        "positive": "Electrical characterization of the azimuthal anisotropy of\n  $(\\mathrm{Ni}_x\\mathrm{Co}_{1-x})\\mathrm{B}$-based ferromagnetic nanotubes: We report on the structural, electric and magnetic properties of\n$(\\mathrm{Ni}_x\\mathrm{Co}_{1-x})\\mathrm{B}$ ferromagnetic nanotubes,\ndisplaying azimuthal magnetization. The tubes are fabricated using electroless\nplating in polycarbonate porous templates, with lengths several tens of\nmicrometers, diameters from 100nm to 500nm and wall thicknesses from 10nm to\n80nm. The resistivity is $\\sim 1.5\\times10^{-6}\\mathrm{\\Omega/m}$, and the\nanisotropic magnetoresistance~(AMR) of 0.2-0.3%, one order of magnitude\nlarger~(resp. smaller) than in the bulk material, which we attribute to the\nresistance at grain boundaries. We determined the azimuthal anisotropy field\nfrom M(H) AMR loops of single tubes contacted electrically. Its magnitude is\naround 10mT, and tends to increase with the tube wall thickness, as well as the\nCo content. However, surprisingly it does not dependent much on the diameter\nnor on the curvature."
    },
    {
        "anchor": "Oscillatory dynamics of non-equilibrium dissipative exciton-polariton\n  condensates in weak-contrast lattices: We study nonlinear dynamics of exciton-polaritons in an incoherently pumped\nsemiconductor microcavity with embedded weak-contrast lattice and coupled to an\nexciton reservoir. We elucidate fundamental features of non-equilibrium\nexciton-polariton condensate trapped in one-dimensional periodical potential\nclose to zero momentum (so-called \"Zero-state\") and to the state at the\nboundary of Brillouin zone (\"$\\pi$-state\"). Within the framework of the\nmean-field theory, we identify different regimes of both relaxation and\noscillatory dynamics of coherent exciton-polaritons governed by superpositions\nof Bloch eigenstates within the periodic lattice. In particular, we\ntheoretically demonstrate stable macroscopical oscillations, akin to nonlinear\nJosephson oscillations, between different spectral components of a polariton\ncondensate in the momenta-space. We elucidate a strong influence of the\ndissipative effects and the feedback induced by the inhomogeneity of incoherent\nreservoir on the dynamics of the coherent polaritons.",
        "positive": "Tunneling and Electric-Field Effects on Electron-Hole Localization in\n  Artificial Molecules: We theoretically investigate the Stark shift of the exciton goundstate in two\nvertically coupled quantum dots as a function of the interdot distance. The\ncoupling is shown to enhance the tuneability of the linear optical properties,\nincluding energy and oscillator strength, as well as the exciton\npolarizability. The coupling regime that maximizes these properties results\nfrom the detailed balance between the effects of the single-particle tunneling,\nof the electric field and of the carrier-carrier interaction. We discuss the\nrelevance of these results to the possible implementation of\nquantum-information processing based on semiconductor quantum dots: in\nparticular, we suggest the identification of the qubits with the exciton levels\nin coupled- rather than single-dots."
    },
    {
        "anchor": "Controlling Fano and Dicke effects via a magnetic flux in a double\n  quantum-dot molecule: The electronic transport through a parallel double quantum-dot molecule\nattached asymmetrically to leads is studied under a magnetic field. We model\nthe system by means of a non interacting two-impurity Anderson Hamiltonian. We\nfind that the conductance shows Fano and Dicke effects that can be controlled\nby the magnetic flux.",
        "positive": "Multi-scale modelling of current-induced switching in magnetic tunnel\n  junctions using ab initio spin transfer torques: There exists a significant challenge in developing efficient magnetic tunnel\njunctions with low write currents for non-volatile memory devices. With the aim\nof analysing potential materials for efficient current-operated magnetic\njunctions we have developed a multi-scale methodology combining the ab initio\ncalculations of spin-transfer torque with large-scale time-dependent\nsimulations using atomistic spin dynamics. In this work we introduce our\nmulti-scale approach including a discussion on a number of possible mapping\nschemes the ab initio spin torques into the spin dynamics. We demonstrate this\nmethodology on a prototype Co/MgO/Co/Cu tunnel junction showing that the spin\ntorques are primarily acting at the interface between the Co free layer and\nMgO. Using spin dynamics we then calculate the reversal switching times for the\nfree layer and the critical voltages and currents required for such switching.\nOur work provides an efficient, accurate and versatile framework for designing\nnovel current-operated magnetic devices, where all the materials details are\ntake into account."
    },
    {
        "anchor": "Disordered Wigner crystals: I review some of the properties of a Wigner crystal of electrons in two\ndimensional systems. The effect of disorder on such quantum crystals is\ndiscussed. The question of compressibility of such systems as obtained from\ncapacitance measurements is examined in details.",
        "positive": "Nonequilibrium transport in quantum impurity models: Exact path integral\n  simulations: We simulate the nonequilibrium dynamics of two generic many-body quantum\nimpurity models by employing the recently developed iterative\ninfluence-functional path integral method [Phys. Rev. B {\\bf 82}, 205323\n(2010)]. This general approach is presented here in the context of quantum\ntransport in molecular electronic junctions. Models of particular interest\ninclude the single impurity Anderson model and the related spinless two-state\nAnderson dot. In both cases we study the time evolution of the dot occupation\nand the current characteristics at finite temperature. A comparison to\nmean-field results is presented, when applicable."
    },
    {
        "anchor": "Unconventional Resistivity Scaling in Topological Semimetal CoSi: Nontrivial band topologies in semimetals lead to robust surface states that\ncan contribute dominantly to the total conduction. This may result in reduced\nresistivity with decreasing feature size contrary to conventional metals, which\nmay highly impact the semiconductor industry. Here we study the resistivity\nscaling of a representative topological semimetal CoSi using realistic band\nstructures and Green's function methods. We show that there exists a critical\nthickness d_c dividing different scaling trends. Above d_c, when the defect\ndensity is low such that surface conduction dominates, resistivity reduces with\ndecreasing thickness; when the defect density is high such that bulk conduction\ndominates, resistivity increases in as conventional metals. Below d_c, the\npersistent remnants of the surface states give rise to decreasing resistivity\ndown to the ultrathin limit, unlike in topological insulators. The observed\nCoSi scaling can apply to broad classes of topological semimetals, providing\nguidelines for materials screening and engineering. Our study shows that\ntopological semimetals bear the potential of overcoming the resistivity scaling\nchallenges in back-end-of-line interconnect applications.",
        "positive": "Adsorption and dynamics of Si atoms at the monolayer Pb/Si(111) surface: In this work, we studied the adsorption behavior of deposited Si atoms along\nwith their diffusion and other dynamic processes on a Pb monolayer-covered\nSi(111) surface from 125-230 K using a variable-temperature scanning tunneling\nmicroscope (STM). The Pb-covered Si(111) surface form a low-symmetry row-like\nstructure in this temperature range and the Si atoms bind favorably to two\nspecific on-top sites (T1A and T1B) on the trimer row after deposition at the\nsample temperature of 125 K. The Si atoms were immobile at low temperatures and\nstarted to switch between the two neighboring T1A and T1B sites within the same\ntrimer when the temperature was raised to 150 K. When the temperature was\nraised above 160 K, the adsorbed Si atoms could hop to other trimers along the\nsame trimer row. Below 170 K, short hops to adjacent trimers dominated, but\nlong hops dominated at temperatures above 170 K. The activation energy and\nprefactor for the Si atoms diffusion were derived through analysis of\ncontinuous-time imaging at temperatures from 160-174 K. In addition,\nirreversible aggregation of single Si atoms into Si clusters started to occur\nat the phase boundaries or defective sites at temperatures above 170 K. This\nstudy provides crucial information for understanding the very initial stage of\nnucleation and growth behavior of epitaxial Si layers on a Pb-covered Si(111)\nsurface. In addition, our study provides strong evidence for breaking in the\nmirror symmetry in the Pb-covered structure, which has implication for the\natomic model of this controversial structure."
    },
    {
        "anchor": "Experimental evidence of robust acoustic valley Hall edge states in a\n  non-resonant topological elastic waveguide: This paper presents experimental evidence of the existence of acoustic valley\nHall (AVHE) edge states in topological elastic waveguides. The fundamental\nlattice is assembled based on a non-resonant unit where space inversion\nsymmetry (SIS) is broken by simply perturbing the underlying lattice geometry.\nThis aspect is in net contrast with existing elastic AVHE designs that exploit\nlocally-resonant units and require the addition of masses in order to break\nSIS. The experimental results presented in this study validate findings so far\npresented only at theoretical and numerical level. In particular, it is found\nthat edge modes can effectively propagate along domain walls between\ntopologically dissimilar domains and that disorder-induced backscattering is\nsubstantially suppressed due to the weak coupling between oppositely\nvalley-polarized modes. The coupling between valley modes is also further\ninvestigated and linked to an evident chiral flux of the mechanical energy.\nFinally, we show that the weak coupling between the valleys can be exploited to\nachieve selective mode injection at the domain wall, hence realizing a very\neffective excitation strategy of the chiral edge states.",
        "positive": "Correlation and current anomalies in helical quantum dots: We theoretically investigate the ground-state properties of a quantum dot\ndefined on the surface of a strong three-dimensional time-reversal invariant\ntopological insulator. Confinement is realized by ferromagnetic barriers and\nCoulomb interaction is treated numerically for up to seven electrons in the\ndot. Experimentally relevant intermediate interaction strengths are considered.\nThe topological nature of the dot has interesting consequences: i) spin\npolarization increases and the ground state exhibits quantum phase transitions\nat specific angular momenta as a function of interaction strength ii) the onset\nof Wigner correlations takes place mainly in one spin channel, iii) the ground\nstate is characterized by a persistent current which changes sign as a function\nof the radius of the dot."
    },
    {
        "anchor": "Purely electrical detection of a skyrmion in constricted geometry: How to detect the skyrmion position is a crucial problem in future\nskyrmionics since it corresponds to the reading process of information. We\npropose a method to detect the skyrmion position purely electrically by\nmeasuring the Hall conductance in a constricted geometry. The Hall conductance\nbecomes maximum when a skyrmion is at the lead position. It is possible to\ndetect the skyrmion position even at room temperature. We find an optimized\nwidth of the sample determined by the skyrmion radius. We also investigate the\neffects of elastic and inelastic scatterings, and finite temperature. We find\nthat the local density of states become minimum at the skyrmion position. Our\nresults will be a basis of future skyrmion electronics.",
        "positive": "Hamiltonian Theory of the Composite Fermion Wigner Crystal: Experimental results indicating the existence of the high magnetic field\nWigner Crystal have been available for a number of years. While variational\nwavefunctions have demonstrated the instability of the Laughlin liquid to a\nWigner Crystal at sufficiently small filling, calculations of the excitation\ngaps have been hampered by the strong correlations. Recently a new Hamiltonian\nformulation of the fractional quantum Hall problem has been developed. In this\nwork we extend the Hamiltonian approach to include states of nonuniform\ndensity, and use it to compute the excitation gaps of the Wigner Crystal\nstates. We find that the Wigner Crystal states near $\\nu=1/5$ are\nquantitatively well described as crystals of Composite Fermions with four\nvortices attached. Predictions for gaps and the shear modulus of the crystal\nare presented, and found to be in reasonable agreement with experiments."
    },
    {
        "anchor": "Sub-electron Charge Relaxation via 2D Hopping Conductors: We have extended Monte Carlo simulations of hopping transport in completely\ndisordered 2D conductors to the process of external charge relaxation. In this\nsituation, a conductor of area $L \\times W$ shunts an external capacitor $C$\nwith initial charge $Q_i$. At low temperatures, the charge relaxation process\nstops at some \"residual\" charge value corresponding to the effective threshold\nof the Coulomb blockade of hopping. We have calculated the r.m.s$.$ value $Q_R$\nof the residual charge for a statistical ensemble of capacitor-shunting\nconductors with random distribution of localized sites in space and energy and\nrandom $Q_i$, as a function of macroscopic parameters of the system. Rather\nunexpectedly, $Q_{R}$ has turned out to depend only on some parameter\ncombination: $X_0 \\equiv L W \\nu_0 e^2/C$ for negligible Coulomb interaction\nand $X_{\\chi} \\equiv LW \\kappa^2/C^{2}$ for substantial interaction. (Here\n$\\nu_0$ is the seed density of localized states, while $\\kappa$ is the\ndielectric constant.) For sufficiently large conductors, both functions\n$Q_{R}/e =F(X)$ follow the power law $F(X)=DX^{-\\beta}$, but with different\nexponents: $\\beta = 0.41 \\pm 0.01$ for negligible and $\\beta = 0.28 \\pm 0.01$\nfor significant Coulomb interaction. We have been able to derive this law\nanalytically for the former (most practical) case, and also explain the scaling\n(but not the exact value of the exponent) for the latter case. In conclusion,\nwe discuss possible applications of the sub-electron charge transfer for\n\"grounding\" random background charge in single-electron devices.",
        "positive": "Crossover from injection to tunneling conduction mode and associated\n  magneto-resistance in a single $Fe_{3}O_{4}$(111)/$Alq_{3}$/Co spin-valve\n  device: We demonstrate interface energy level engineering, exploiting the\nmodification in energy band structure across Verwey phase transition of\n$Fe_{3}O_{4}$ electrode, in a $Fe_{3}O_{4}$(111)/$Alq_{3}$/Co vertical\nspin-valve (SV) device. Experimental results on device characteristics I-V)\nstudy exhibit a transition in conduction mode from carrier injection to\ntunneling across Verwey transition temperature ($T_{V}$) of $Fe_{3}O_{4}$\nelectrode. Both giant magneto-resistance (GMR) and tunneling MR (TMR) have been\nobserved in a single SV device as a function of temperature, below and above\n$T_{V}$, respectively. Appearance of GMR, accompanied by injection limited\nnatural Schottky-like I-V characteristics, provide evidences of spin injection\nat electrode/$Alq_{3}$ interface and transport through molecular orbitals in\nthis SV device. Features of TMR exhibit significant differences from that of\nGMR. This is due to the dominant hyperfine-field interaction in the multi-step\ntunneling regime. We have achieved room-temperature SV operation in our device.\nA phenomenological model for device operation has been proposed to explain the\ntransition in the conduction mode and associated MR features across $T_{V}$. We\npropose that the tuning of charge gap at Fermi level across Verwey transition\ndue to charge ordering on the octahedral iron sites of $Fe_{3}O_{4}$ results in\na corresponding tuning of conduction mode causing this unique cross over from\nGMR to TMR in this ferrite-based organic SV."
    },
    {
        "anchor": "Finite-size effects on the minimal conductivity in graphene with Rashba\n  spin-orbit coupling: We study theoretically the minimal conductivity of monolayer graphene in the\npresence of Rashba spin-orbit coupling. The Rashba spin-orbit interaction\ncauses the low-energy bands to undergo trigonal-warping deformation and for\nenergies smaller than the Lifshitz energy, the Fermi circle breaks up into\nparts, forming four separate Dirac cones. We calculate the minimal conductivity\nfor an ideal strip of length $L$ and width $W$ within the Landauer--B\\\"uttiker\nformalism in a continuum and in a tight binding model. We show that the minimal\nconductivity depends on the relative orientation of the sample and the probing\nelectrodes due to the interference of states related to different Dirac cones.\nWe also explore the effects of finite system size and find that the minimal\nconductivity can be lowered compared to that of an infinitely wide sample.",
        "positive": "Spin Effects in the Local Density of States of GaAs: We present spin-resolved measurements of the local density of states in Si\ndoped GaAs. Both spin components exhibit strong mesoscopic fluctuations. In the\nmagnetic quantum limit, the main features of the spin-up and spin-down\ncomponents of the local density of states are found to be identical apart from\nZeeman splitting. Based on this observation, we introduce a mesoscopic method\nto measure the $g$-factor in a material where macroscopic methods are severely\nrestricted by disorder. Differences between the spin-up and spin-down\ncomponents are discussed in terms of spin relaxation due to spin-orbit\ncoupling."
    },
    {
        "anchor": "A geometric protocol for a robust Majorana magic gate: A universal quantum computer requires a full set of basic quantum gates. With\nMajorana bound states one can form all necessary quantum gates in a\ntopologically protected way, bar one. In this manuscript we present a protocol\nthat achieves the missing, so called, $\\pi/8$ 'magic' phase gate. The protocol\nis based on the manipulation of geometric phases in a universal manner, and\ndoes not require fine tuning for distinct physical realizations. The protocol\nconverges exponentially with the number of steps in the geometric path.\nFurthermore, the magic gate protocol relies on the most basic hardware\npreviously suggested for topologically protected gates, and can be extended to\nany-phase-gate, where $\\pi/8$ is substituted by any $\\alpha$.",
        "positive": "Charge-memory effect in a polaron model: equation-of-motion method for\n  Green functions: We analyze a single-level quantum system placed between metallic leads and\nstrongly coupled to a localized vibrational mode, which models a singlemolecule\njunction or an STM setup. We consider a polaron model describing the\ninteraction between electronic and vibronic degrees of freedom and develop and\nexamine different truncation schemes in the equation-of-motion method within\nthe framework of non-equilibrium Green functions. We show that upon applying\ngate or bias voltage, it is possible to observe charge-bistability and\nhysteretic behavior which can be the basis of a charge-memory element. We\nfurther perform a systematic analysis of the bistability behaviour of the\nsystem for different internal parameters such as the electron-vibron and the\nlead-molecule coupling strength."
    },
    {
        "anchor": "Thermoplasmonics: Quantifying plasmonic heating in single nanowires: Plasmonic absorption of light can lead to significant local heating in\nmetallic nanostructures, an effect that defines the sub-field of\nthermoplasmonics and has been leveraged in diverse applications from biomedical\ntechnology to optoelectronics. Quantitatively characterizing the resulting\nlocal temperature increase can be very challenging in isolated nanostructures.\nBy measuring the optically-induced change in resistance of metal nanowires with\na transverse plasmon mode, we quantitatively determine the temperature increase\nin single nanostructures, with the dependence on incident polarization clearly\nrevealing the plasmonic heating mechanism. Computational modeling explains the\nresonant and nonresonant contributions to the optical heating and the dominant\npathways for thermal transport. These results, obtained by combining electronic\nand optical measurements, place a bound on the role of optical heating in prior\nexperiments, and suggest design guidelines for engineered structures meant to\nleverage such effects.",
        "positive": "Multilevel recording in Bi-deficient Pt/BFO/SRO heterostructures based\n  on ferroelectric resistive switching targeting high-density information\n  storage in nonvolatile memories: We demonstrate the feasibility of multilevel recording in\nPt/Bi(1-d)FeO3/SrRuO3 capacitors using the ferroelectric resistive switching\nphenomenon exhibited by the Pt/Bi(1-d)FeO3 interface. A tunable population of\nup and down ferroelectric domains able to modulate the Schottky barrier height\nat the Pt/Bi(1-d)FeO3 interface can be achieved by means of either a collection\nof SET/RESET voltages or current compliances. This programming scheme gives\nrise to well defined resistance states, which form the basis for a multilevel\nstorage nonvolatile memory."
    },
    {
        "anchor": "Correlation between In content and emission wavelength of InGaN/GaN\n  nanowire heterostructures: GaN nanowire ensembles with axial InGaN multi-quantum wells (MQWs) were grown\nby molecular beam epitaxy. In a series of samples, we varied the In content in\nthe MQWs from almost zero to about 20%. Within the nanowire ensemble, the MQWs\nfluctuate strongly in composition and size. Statistical information about the\ncomposition was obtained from x-ray diffraction and Raman spectroscopy.\nPhotoluminescence at room temperature was obtained in the range from 2.2 eV to\n2.5 eV depending on In content. Contrary to planar MQWs, the intensity\nincreases with increasing In content. We compare the observed emission energies\nwith transition energies obtained from a one-dimensional model, and conclude\nthat several mechanisms for carrier localization affect the luminescence of\nthese three-dimensional structures.",
        "positive": "Theory of topological excitations and metal-insulator transition in\n  reentrant integer quantum Hall effect: The reentrant integer quantum Hall effects (RIQHE) are due to formation of\nelectronic crystals. We show analytically and numerically that topological\ntextures in the charge density distribution in these crystals in the vicinity\nof charged defects strongly reduce energy required for current-carrying\nexcitations. The theory quantitatively explains sharp insulator-metal\ntransitions experimentally observed in RIQHE states. The insulator to metal\ntransition in RIQHE emerges as a thermodynamic unbinding transition of\ntopological charged defects."
    },
    {
        "anchor": "Electron tunneling through a single magnetic barrier in HgTe topological\n  insulator: Electron tunneling through a single magnetic barrier in a HgTe topological\ninsulator has been theoretically investigated. We find that the perpendicular\nmagnetic field would not lead to spin-flip of the edge states due to the\nconservation of the angular moment. By tuning the magnetic field and Fermi\nenergy, the edge channels can be transited from switch-on states to switch-off\nstates and the current can be transmitted from unpolarized states to totally\nspin polarized states. These features offer us and efficient way to control the\ntopological edge state transport, and pave a way to construct the\nnanoelectronic devices utilizing the topological edge states.",
        "positive": "Spin beats in the photoluminescence polarization dynamics of charged\n  excitons in InP/(In,Ga)P quantum dots in presence of nuclear quadrupole\n  interaction: The spin dynamics of positively (X$^{+}$) and negatively (X$^{-}$) charged\nexcitons in InP/In$_{0.48}$Ga$_{0.52}$P quantum dots subject to a magnetic\nfield is studied. We find that a characteristic feature of the system under\nstudy is the presence of nuclear quadrupole interaction, which leads to\nstabilization of the nuclear and electron spins in a quantum dot in zero\nexternal magnetic field. In detail, the nuclear quadrupole interaction leads to\npinning of the Overhauser field along the quadrupole axis, which is close to\nthe growth axis of the heterostructure. The nuclear effects are observed only\nwhen resident electrons are confined in the quantum dots, i.e. for X$^{-}$\ntrion photoexcitation. The presence of X$^{-}$ and X$^{+}$ trion contributions\nto the photoluminescence together with the quadrupole interaction significantly\naffects the dynamics of optical orientation in Voigt magnetic field. In absence\nof dynamic nuclear spin polarization the time evolution of the\nphotoluminescence polarization was fitted by a form which describes the\nelectron spin relaxation in \"frozen\" nuclear field fluctuations. In relatively\nlarge external magnetic fields exceeding 60 mT good agreement between theory\nand experiment is achieved."
    },
    {
        "anchor": "D'yakonov-Perel' spin relaxation in InSb/AlInSb quantum wells: We investigate theoretically the D'yakonov-Perel' spin relaxation time by\nsolving the eight-band Kane model and Poisson equation self-consistently. Our\nresults show distinct behavior with the single-band model due to the anomalous\nspin-orbit interactions in narrow band-gap semiconductors, and agree well with\nthe experiment values reported in recent experiment (K. L. Litvinenko, et al.,\nNew J. Phys. \\textbf{8}, 49 (2006)). We find a strong resonant enhancement of\nthe spin relaxation time appears for spin align along [$1\\bar{1}0$] at a\ncertain electron density at 4 K. This resonant peak is smeared out with\nincreasing the temperature.",
        "positive": "Scattering matrix of arbitrary tight-binding Hamiltonians: A novel efficient method to calculate the scattering matrix (SM) of arbitrary\ntight-binding Hamiltonians is proposed, including cases with multiterminal\nstructures. In particular, the SM of two kind of fundamental structures are\ngiven, which can be used to obtain the SM of bigger systems iteratively. Also,\na procedure to obtain the SM of layer-composed periodic leads is described.\nThis method allows renormalization approaches, which permits computations over\nmacroscopic length systems without introducing additional approximations.\nFinally, the transmission coefficient of a ring-shaped multiterminal system and\nthe transmission function of a square-lattice nanoribbon with a reduced width\nregion are calculated."
    },
    {
        "anchor": "Asymmetric voltage noise in superconducting tunnel junctions with\n  electromagnetic environment: We investigate theoretically the V-I characteristics and voltage noise of\nsuperconducting tunnel junctions with small critical current via the\nmatrix-continued-fraction method. Special attention is paid to the large\nhysteresis in the V-I characteristics and to the voltage-noise anomaly observed\nin preliminary experiments. The current dependence of the voltage noise shows a\nstrong asymmetry between the forward and backward current ramping and a\ndiscontinuous change of the noise close to its measured maximum occurring at\nthe switching current. We show that both the large hysteresis and the voltage\nnoise anomaly in this current-biased setup are a consequence of the influence\nof junction's electromagnetic environment. Typically, the voltage-noise\ndependence on the junction current parametrized by the external drive contains\na loop which is, however, not observed experimentally because of the\nimplementation of the junction-current ramp. Skipping a part of the loop is\nresponsible for the observed hysteresis as well as the noise anomaly.",
        "positive": "Rydberg series of dark excitons and the conduction band spin-orbit\n  splitting in monolayer WSe$_2$: Strong Coulomb correlations together with multi-valley electronic bands in\nthe presence of spin-orbit interaction and possible new optoelectronic\napplications are at the heart of studies of the rich physics of excitons in\nsemiconductor structures made of monolayers of transition metal dichalcogenides\n(TMD). In intrinsic TMD monolayers the basic, intravalley excitons are formed\nby a hole from the top of the valence band and an electron either from the\nlower or upper spin-orbit-split conduction band subbands: one of these excitons\nis optically active, the second one is \"dark\", although possibly observed under\nspecial conditions. Here we demonstrate the s-series of Rydberg dark exciton\nstates in monolayer WSe$_2$, which appears in addition to a conventional bright\nexciton series in photoluminescence spectra measured in high in-plane magnetic\nfields. The comparison of energy ladders of bright and dark Rydberg excitons is\nshown to be a method to experimentally evaluate one of the missing band\nparameters in TMD monolayers: the amplitude of the spin-orbit splitting of the\nconduction band."
    },
    {
        "anchor": "Magneto-polaritons in Weyl semimetals in a strong magnetic field: Exotic topological and transport properties of Weyl semimetals generated a\nlot of excitement in the condensed matter community. Here we show that Weyl\nsemimetals in a strong magnetic field are highly unusual optical materials. The\npropagation of electromagnetic waves is affected by an interplay between\nplasmonic response of chiral Weyl fermions and extreme anisotropy induced by a\nmagnetic field. The resulting magneto-polaritons possess a number of peculiar\nproperties, such as hyperbolic dispersion, photonic stop bands,\ncoupling-induced transparency, and broadband polarization conversion. These\neffects can be used for optical spectroscopy of these materials including\ndetection of the chiral anomaly, or for broadband terahertz/infrared\napplications.",
        "positive": "Antiferromagnetic THz-frequency Josephson-like Oscillator Driven by Spin\n  Current: The development of compact and tunable room temperature sources of coherent\nTHz-frequency signals would open a way for numerous new applications. The\nexisting approaches to THz-frequency generation based on superconductor\nJosephson junctions (JJ), free electron lasers, and quantum cascades require\ncryogenic temperatures or/and complex setups, preventing the miniaturization\nand wide use of these devices. We demonstrate theoretically that a bi-layer of\na heavy metal (Pt) and a bi-axial antiferromagnetic (AFM) dielectric (NiO) can\nbe a source of a coherent THz signal. A spin-current flowing from a\nDC-current-driven Pt layer and polarized along the hard AFM anisotropy axis\nexcites a non-uniform in time precession of magnetizations sublattices in the\nAFM, due to the presence of a weak easy-plane AFM anisotropy. The frequency of\nthe AFM oscillations varies in the range of 0.1-2.0 THz with the driving\ncurrent in the Pt layer from $10^8\\text{A}/\\text{cm}^2$ to\n$10^9\\text{A}/\\text{cm}^2$. The THz-frequency signal from the AFM with the\namplitude exceeding 1 V/cm is picked up by the inverse spin-Hall effect in Pt.\nThe operation of a room-temperature AFM THz-frequency oscillator is similar to\nthat of a cryogenic JJ oscillator, with the energy of the easy-plane magnetic\nanisotropy playing the role of the Josephson energy."
    },
    {
        "anchor": "Fabrication of nanopores in a graphene sheet with heavy ions: a\n  molecular dynamics study: Molecular dynamics (MD) simulations were performed to study the formation\nprocess of nanopores in a suspended graphene sheet irradiated by using\nenergetic ions though a mask. By controlling the ion parameters including mass,\nenergy and incident angle, different kinds of topography were observed in the\ngraphene sheet. Net-like defective strucutures with carbon atom chains can be\nformed at low ion fluence, which provides the possibility to functionalize the\nirradiated sample with subsequent chemical methods; finally a perfect nanopore\nwith smooth edge appears as the ion fluence is high enough. We found that the\ndependence of ion damage efficiency on ion fluence, energy and incident angle\nare different from that predicted by the semi-empirical model based on the\nbinary-collision approximation, which results from the special structure of\ngraphene. Our results demonstrate that it is feasible to fabricate controlled\nnanopores/nanostructures in graphene via heavy ion irradiation.",
        "positive": "Stability of quantized conductance levels in memristors with copper\n  filaments: toward understanding the mechanisms of resistive switching: Memristors are among the most promising elements for modern microelectronics,\nhaving unique properties such as quasi-continuous change of conductance and\nlong-term storage of resistive states. However, identifying the physical\nmechanisms of resistive switching and evolution of conductive filaments in such\nstructures still remains a major challenge. In this work, aiming at a better\nunderstanding of these phenomena, we experimentally investigate an unusual\neffect of enhanced conductive filament stability in memristors with copper\nfilaments under the applied voltage and present a simplified theoretical model\nof the effect of a quantum current through a filament on its shape. Our\nsemi-quantitative, continuous model predicts, indeed, that for a thin filament,\nthe \"quantum pressure\" exerted on its walls by the recoil of charge carriers\ncan well compete with the surface tension and crucially affect the evolution of\nthe filament profile at the voltages around 1V. At lower voltages, the quantum\npressure is expected to provide extra stability to the filaments supporting\nquantized conductance, which we also reveal experimentally using a novel\nmethodology focusing on retention statistics. Our results indicate that the\nrecoil effects could potentially be important for resistive switching in\nmemristive devices with metallic filaments and that taking them into account in\nrational design of memristors could help achieve their better retention and\nplasticity characteristics."
    },
    {
        "anchor": "Orbital Hall Insulating Phase in Transition Metal Dichalcogenide\n  Monolayers: We show that H-phase transition metal dichalcogenides (TMDs) monolayers such\nas MoS$_2$ and WSe$_2$, are orbital Hall insulators. They present very large\norbital Hall conductivity plateaus in their semiconducting gap, where the spin\nHall conductivity vanishes. Our results open the possibility of using TMDs for\norbital current injection and orbital torque transfers that surpass their\nspin-counterparts in spin-orbitronics devices. The orbital Hall effect (OHE) in\nTMD monolayers occurs even in the absence of spin-orbit coupling. It can be\nlinked to exotic momentum-space Dresselhaus-like orbital textures, analogous to\nthe spin-momentum locking in 2D Dirac fermions that arise from a combination of\norbital attributes and lattice symmetry.",
        "positive": "Hot Electron Terahertz Oscillations in Graphene: Crater and Terraces in\n  the Carrier Distribution Function: In graphene, after the electric field is turned-on, the ballistic\nacceleration of charge carriers up to the monochromatic optic phonon energy\ngenerates a back-and-forth motion of the whole distribution function between\nthe zero point energy and the phonon energy. This effect is predicted to\nmanifest in damped terahertz oscillations of the carrier drift velocity and\naverage energy. The most dramatic feature of this transient phenomenon is the\nonset of momentum-free areas surrounded by high momentum probability in phase\nspace, and smooth steps or terraces in the distribution function. This\ndynamical effect that only takes place within a voltage and sample length\nwindow, is the direct consequence of the interplay between the electric force\nand the randomizing nature of deformation potential optic phonons in the linear\nband structure of graphene."
    },
    {
        "anchor": "Electric field funnels for guiding charged nanoparticles. Simple models\n  for exact solutions: Static electric fields can be configured to guide charged nanoparticles along\nthe electric field lines. Some field line configurations can focus the\nnanoparticles to prescribed places thus acting as electric funnels. Despite the\nimportance of funnels for nanoprinting , there is a lack of formulation and\nunderstanding. We present two solvable models in two dimensions (2D) as far as\nit allows one to use the complex plane for exact calculation of the field\nlines. One model deals with two fixed dipoles such that the external electric\nfield tries to squeeze through between them thus forming a funnel. The other\none deals with a couple of parallel conducting plates with a hole where the\nexternal field comes through also creating a funnel. The results obtained may\nbe useful for configuring the electric field for nanoprinting engineering.",
        "positive": "Exact Higher-order Bulk-boundary Correspondence of Corner-localized\n  States: We demonstrate that the presence of a localized state at the corner of an\ninsulating domain is not always a predictor of a certain non-trivial\nhigher-order topological invariant, even though they appear to co-exist in the\nsame Hamiltonian parameter space. Our analysis of $C^n$-symmetric crystalline\ninsulators and their multi-layer stacks reveals that topological corner states\nare not necessarily correlated with other well-established higher-order\nboundary observables, such as fractional corner charge or filling anomaly. In a\n$C^3$-symmetric breathing Kagome lattice, for example, we show that the bulk\npolarization, which successfully predicts the fractional corner anomaly, fails\nto be the relevant topological invariant for zero-energy corner states;\ninstead, these corner states can be exactly explained by the decoration of\ntopological edges. Also, while the zero-energy corner states in $C^4$-symmetric\ntopological crystalline insulators have long been conjectured to be the result\nof the bulk polarization at quarter-filling, we correct this misconception by\nintroducing a proper bulk invariant at half-filling and establishing a precise\nbulk-corner correspondence. By refining several bulk-corner correspondences in\ntwo-dimensional topological crystalline insulators, our work motivates further\ndevelopment of rigorous theoretical grounds for associating the existence of\ncorner states with higher-order topology of host materials."
    },
    {
        "anchor": "A Note on Bloch theorem: Bloch theorem in ordinary quantum mechanics means the absence of the total\nelectric current in equilibrium. In the present paper we analyze the\npossibility that this theorem remains valid within quantum field theory\nrelevant for the description of both high energy physics and condensed matter\nphysics phenomena. First of all, we prove that the total electric current in\nequilibrium is the topological invariant for the gapped fermions that are\nsubject to periodical boundary conditions, i.e. it is robust to the smooth\nmodification of such systems. This property remains valid when the inter -\nfermion interactions due to the exchange by bosonic excitations are taken into\naccount perturbatively. We give the proof of this statement to all orders in\nperturbation theory. Thus we prove the weak version of the Bloch theorem, and\nconclude that the total current remains zero in any system, which is obtained\nby smooth modification of the one with the gapped charged fermions, periodical\nboundary conditions, and vanishing total electric current. We analyse several\nexamples, in which the fermions are gapless. In some of them the total electric\ncurrent vanishes. At the same time we propose the counterexamples of the\nequilibrium gapless systems, in which the total electric current is nonzero.",
        "positive": "Single-electron current sources: towards a refined definition of ampere: Controlling electrons at the level of elementary charge $e$ has been\ndemonstrated experimentally already in the 1980's. Ever since, producing an\nelectrical current $ef$, or its integer multiple, at a drive frequency $f$ has\nbeen in a focus of research for metrological purposes. In this review we first\ndiscuss the generic physical phenomena and technical constraints that influence\ncharge transport. We then present the broad variety of proposed realizations.\nSome of them have already proven experimentally to nearly fulfill the demanding\nneeds, in terms of transfer errors and transfer rate, of quantum metrology of\nelectrical quantities, whereas some others are currently \"just\" wild ideas,\nstill often potentially competitive if technical constraints can be lifted. We\nalso discuss the important issues of read-out of single-electron events and\npotential error correction schemes based on them. Finally, we give an account\nof the status of single-electron current sources in the bigger framework of\nelectric quantum standards and of the future international SI system of units,\nand briefly discuss the applications and uses of single-electron devices\noutside the metrological context."
    },
    {
        "anchor": "Disorder-quenched Kondo effect in mesosocopic electronic systems: Nonmagnetic disorder is shown to quench the screening of magnetic moments in\nmetals, the Kondo effect. The probability that a magnetic moment remains free\ndown to zero temperature is found to increase with disorder strength.\nExperimental consequences for disordered metals are studied. In particular, it\nis shown that the presence of magnetic impurities with a small Kondo\ntemperature enhances the electron's dephasing rate at low temperatures in\ncomparison to the clean metal case. It is furthermore proven that the width of\nthe distribution of Kondo temperatures remains finite in the thermodynamic\n(infinite volume) limit due to wave function correlations within an energy\ninterval of order $1/\\tau$, where $\\tau$ is the elastic scattering time. When\ntime-reversal symmetry is broken either by applying a magnetic field or by\nincreasing the concentration of magnetic impurities, the distribution of Kondo\ntemperatures becomes narrower.",
        "positive": "Spin entangled state transfer in quantum dot arrays: Coherent adiabatic\n  and speed-up protocols: Long-distance transfer of quantum states is an indispensable part of\nlarge-scale quantum information processing. We propose a novel scheme for the\ntransfer of two-electron entangled states, from one edge of a quantum dot array\nto the other by coherent adiabatic passage. This protocol is mediated by pulsed\ntunneling barriers. In a second step, we seek for a speed up by shortcut to\nadiabaticity techniques. This significantly reduces the operation time and,\nthus, minimizes the impact of decoherence. For typical parameters of\nstate-of-the-art solid state devices, the accelerated protocol has an operation\ntime in the nanosecond range and terminates before a major coherence loss sets\nin. The scheme represents a promising candidate for entanglement transfer in\nsolid state quantum information processing."
    },
    {
        "anchor": "A Short Course on Topological Insulators: Band-structure topology and\n  edge states in one and two dimensions: This course-based primer provides newcomers to the field with a concise\nintroduction to some of the core topics in the emerging field of topological\nband insulators in one and two dimensions. The aim is to provide a basic\nunderstanding of edge states, bulk topological invariants, and of the\nbulk--boundary correspondence with as simple mathematical tools as possible. We\nuse noninteracting lattice models of topological insulators, building gradually\non these to arrive from the simplest one-dimensional case (the\nSu-Schrieffer-Heeger model for polyacetylene) to two-dimensional time-reversal\ninvariant topological insulators (the Bernevig-Hughes-Zhang model for HgTe). In\neach case the model is introduced first and then its properties are discussed\nand subsequently generalized. The only prerequisite for the reader is a working\nknowledge in quantum mechanics, the relevant solid state physics background is\nprovided as part of this self-contained text, which is complemented by\nend-of-chapter problems.",
        "positive": "Enhanced electron transfer using NiCo2O4@C hollow nanocages with an\n  electron-shuttle effect for efficient tetracycline degradation: Spinel oxides are recognized as promising Fenton-like catalysts for the\ndegradation of antibiotics. However, the catalytic performance is restrained by\nthe poor electron transfer rate (ETR). Herein, hollow NiCo2O4@C nanocages are\nrationally designed and prepared to accelerate ETR in peroxymonosulfate (PMS)\nactivation for tetracycline (TC) degradation."
    },
    {
        "anchor": "Quantum decoherence dynamics of divacancy spins in silicon carbide: Long coherence times are key to the performance of quantum bits (qubits).\nHere, we experimentally and theoretically show that the Hahn-echo coherence\ntime (T2) of electron spins associated with divacancy defects in 4H-SiC reaches\n1.3 ms, one of the longest T2 times of an electron spin in a naturally isotopic\ncrystal. Using a first-principles microscopic quantum-bath model, we find that\ntwo factors determine the unusually robust coherence. First, in the presence of\nmoderate magnetic fields (300 G and above), the 29Si and 13C paramagnetic\nnuclear spin baths are decoupled. In addition, because SiC is a binary crystal,\nhomo-nuclear spin pairs are both diluted and forbidden from forming strongly\ncoupled, nearest-neighbor spin pairs. Longer neighbor distances result in fewer\nnuclear spin flip-flops, a less fluctuating intra-crystalline magnetic\nenvironment, and thus a longer T2 time. Our results point to polyatomic\ncrystals as promising hosts for coherent qubits in the solid state.",
        "positive": "Overcoming temperature limits in the optical cooling of solids using\n  light-dressed states: Laser cooling of solids currently has a temperature floor of 50 - 100 K. We\npropose a method that could overcome this using defects, such as diamond color\ncenters, with narrow electronic manifolds and bright optical transitions. It\nexploits the dressed states formed in strong fields which extend the set of\nphonon transitions and have tunable energies. This allows an enhancement of the\ncooling power and diminishes the effect of inhomogeneous broadening. We\ndemonstrate these effects theoretically for the silicon-vacancy and the\ngermanium-vacancy, and discuss the role of background absorption,\nphonon-assisted emission, and non-radiative decay."
    },
    {
        "anchor": "Magnetism of Substitutional Co Impurities in Graphene: Realization of\n  Single $\u03c0$-Vacancies: We report {\\it ab initio} calculations of the structural, electronic and\nmagnetic properties of a graphene monolayer substitutionally doped with Co\n(Co$_{sub}$) atoms. We focus in Co because among traditional ferromagnetic\nelements (Fe, Co and Ni), only Co$_{sub}$ atoms induce spin-polarization in\ngraphene. Our results show the complex magnetism of Co substitutional impurites\nin graphene, which is mapped into simple models such as the $\\pi$-vacancy and\nHeisenberg model. The links established in our work can be used to bring into\ncontact the engineering of nanostructures with the results of $\\pi$-models in\ndefective graphene. In principle, the structures considered here can be\nfabricated using electron irradiation or Ar$^+$ ion bombardment to create\ndefects and depositing Co at the same time.",
        "positive": "Valley-dependent tunneling through electrostatically created quantum\n  dots in heterostructures of graphene with hexagonal boron nitride: Kelvin probe force microscopy (KPFM) has been employed to probe charge\ncarriers in a graphene/hexagonal boron nitride (hBN) heterostructure [Nano\nLett, 21, 5013 (2021)]. We propose an approach for operating valley filtering\nbased on the KPFM-induced potential $U_0$ instead of using external or induced\npseudo-magnetic fields in strained graphene. Employing a tight-binding model,\nwe investigate the parameters and rules leading to valley filtering in the\npresence of a graphene quantum dot (GQD) created by the KPFM tip. This model\nleads to a resolution of different transport channels in reciprocal space,\nwhere the electron transmission probability at each Dirac cone ($K_1$= -K and\n$K_2$ = +K) is evaluated separately. The results show that U0 and the Fermi\nenergy $E_F$ control (or invert) the valley polarization, if electrons are\nallowed to flow through a given valley. The resulting valley filtering is\nallowed only if the signs of $E_F$ and $U_0$ are the same. If they are\ndifferent, the valley filtering is destroyed and might occur only at some\nresonant states affected by $U_0$. Additionally, there are independent valley\nmodes characterizing the conductance oscillations near the vicinity of the\nresonances, whose strength increases with $U_0$ and are similar to those\noccurring in resonant tunneling in quantum antidots and to the Fabry-Perot\noscillations. Using KPFM, to probe the charge carriers, and graphene-based\nstructures to control valley transport, provides an efficient way for attaining\nvalley filtering without involving external or pseudo-magnetic fields as in\nprevious proposals."
    },
    {
        "anchor": "Beating pattern in quantum magnetotransport coefficients of spin-orbit\n  coupled Dirac fermions in gated silicene: We report theoretical study of magnetotransport coefficients of spin-orbit\ncoupled gated silicene in presence and absence of spatial periodic modulation.\nThe combined effect of spin-orbit coupling and perpendicular electric field\nmanifests through formation of regular beating pattern in Weiss and SdH\noscillations. Analytical results, in addition to the numerical results, of the\nbeating pattern formation are provided. The analytical results yield a beating\ncondition which will be useful to determine the spin-orbit coupling constant by\nsimply counting the number of oscillation between any two successive nodes.\nMoreover, the numerical results of modulation effect on collisional and Hall\nconductivities are presented.",
        "positive": "Two-dimensional topological solitons in small exchange-dominated\n  cylindrical ferromagnetic particles: A general approach allowing to construct the magnetization distributions of\narbitrary topological charge in small exchange-dominated cylindrical\nferromagnetic particles is presented. The exchange energy functional is\nminimized by these distributions exactly. The magnetostatic energy is accounted\npartially, so that it facilitates a choice between the topologically equivalent\nexchange-only solutions. The resulting magnetization distributions can be\neasily generalized to a variety of non-circular cylindrical shapes by means of\na conformal transformation. As an example a magnetic structures of a thin\ncircular ferromagnetic cylinder both with centered and displaced magnetic\nvortex and of a finite Bloch domain wall in an elongated particle is given."
    },
    {
        "anchor": "Long range of indirect exchange interaction on the edges of MoS$_{2}$\n  flakes: We study the Ruderman-Kittel-Kasuya-Yosida interaction between two magnetic\nimpurities connected to the edges of zigzag-terminated MoS$_{2}$ flakes. When\nthe impurities lie on the edges of the flake, the effective exchange\ninteraction exhibits sizable noncollinear Dzyaloshinskii-Moriya character that\ncompetes with a strong Ising coupling. We analyze the characteristic decay\nexponent for doping levels inside the band gap of the infinite layer,\ncorresponding to edge states of the flake at the Fermi level. The\ncharacteristic exponents show sub-two-dimensional (sub-2D) behavior for these\nband fillings, with decays much slower than quadratic. The Ising interaction\nhas effectively one-dimensional (1D) long range, while the noncollinear\ncomponent that grows for short impurity separation becomes comparable in\nmagnitude. The resulting tunable exchange interaction on these systems opens\nthe way for the study of interesting phases of impurity arrays with long-range\nstable helical order.",
        "positive": "Universal features of electron-phonon interactions in atomic wires: The effect of electron-phonon interactions in the conductance through\nmetallic atomic wires is theoretically analyzed. The proposed model allows to\nconsider an atomic size region electrically and mechanically coupled to bulk\nelectrodes. We show that under rather general conditions the features due to\nelectron-phonon coupling are described by universal functions of the system\ntransmission coefficients. It is predicted that the reduction of the\nconductance due to electron-phonon coupling which is observed close to perfect\ntransmission should evolve into an enhancement at low transmission. This\ncrossover can be understood in a transparent way as arising from the\ncompetition between elastic and inelastic processes."
    },
    {
        "anchor": "Magnetoconductance Oscillations in Electron-hole Hybridization Gaps and\n  Valley Splittings in Tetralayer Graphene: We investigate magnetotransport on Bernal-stacked tetralayer graphene whose\nband structure consists of two massive subbands with different effective\nmasses. Under a finite displacement field, we observe valley splitting of\nLandau levels (LLs) only in the light-mass subband, consistent with a\ntight-binding model. At low density, we find unexpected magnetoconductance\noscillations in bulk gaps which originate from a series of hybridizations\nbetween electron-like and hole-like LLs due to band inversion in tetralayer\ngraphene. In contrast to a trivial LL quantization gap, these inverted\nhybridization gaps can lead to a change in number of edge states which explains\nthe observed oscillations.",
        "positive": "Fano Resonances in Electronic Transport through a Single Electron\n  Transistor: We have observed asymmetric Fano resonances in the conductance of a single\nelectron transistor resulting from interference between a resonant and a\nnonresonant path through the system. The resonant component shows all the\nfeatures typical of quantum dots, but the origin of the non-resonant path is\nunclear. A unique feature of this experimental system, compared to others that\nshow Fano line shapes, is that changing the voltages on various gates allows\none to alter the interference between the two paths."
    },
    {
        "anchor": "Remarks on the tight-binding model of graphene: We address a simple but fundamental issue arising in the study of graphene,\nas well as of other systems that have a crystalline structure with more than\none atom per unit cell. For these systems, the choice of the tight-binding\nbasis is not unique. For monolayer graphene two bases are widely used in the\nliterature. While the expectation values of operators describing physical\nquantities should be independent of basis, the form of the operators may depend\non the basis, especially in the presence of disorder or of an applied magnetic\nfield. Using the inappropriate form of certain operators may lead to erroneous\nphysical predictions. We discuss the two bases used to describe monolayer\ngraphene, as well as the form of the most commonly used operators in the two\nbases. We repeat our analysis for the case of bilayer graphene.",
        "positive": "Weyl-point teleportation: In this work, we describe the phenomenon of Weyl-point teleportation. Weyl\npoints usually move continuously in the configuration parameter space of a\nquantum system when the control parameters are varied continuously. However,\nthere are special transition points in the control space where the continuous\nmotion of the Weyl points is disrupted. In such transition points, an extended\nnodal structure (nodal line or nodal surface) emerges, serving as a wormhole\nfor the Weyl points, allowing their teleportation in the configuration space. A\ncharacteristic side effect of the teleportation is that the motional\nsusceptibility of the Weyl point diverges in the vicinity of the transition\npoint, and this divergence is characterized by a universal scaling law. We\nexemplify these effects via a two-spin model and a Weyl Josephson circuit\nmodel. We expect that these effects generalize to many other settings including\nelectronic band structures of topological semimetals."
    },
    {
        "anchor": "Conserved spin current for the Mott relation: The conserved bulk spin current [Shi et al., Phys. Rev. Lett. 96, 076604\n(2006)], defined as the time derivative of the spin displacement operator,\nensures automatically the Onsager relation between the spin Hall effect (SHE)\nand the inverse SHE. Here, we reveal another desirable property of this\nconserved spin current: the Mott relation linking the SHE and its thermal\ncounterpart, the spin Nernst effect (SNE). According to the Mott relation, the\nSNE is known once the SHE is understood. In a two-dimensional Dirac-Rashba\nsystem with a smooth scalar disorder potential, we find a sign change of the\nspin Nernst conductivity when tuning the chemical potential.",
        "positive": "Observation of an in-plane magnetic-field-driven phase transition in a\n  quantum Hall system with SU(4) symmetry: In condensed matter physics, the study of electronic states with SU(N)\nsymmetry has attracted considerable and growing attention in recent years, as\nsystems with such a symmetry can often have a spontaneous symmetry-breaking\neffect giving rise to a novel ground state. For example, pseudospin quantum\nHall ferromagnet of broken SU(2) symmetry has been realized by bringing two\nLandau levels close to degeneracy in a bilayer quantum Hall system. In the past\nseveral years, the exploration of collective states in other multi-component\nquantum Hall systems has emerged. Here we show the conventional pseudospin\nquantum Hall ferromagnetic states with broken SU(2) symmetry collapsed rapidly\ninto an unexpected state with broken SU(4) symmetry, by in-plane magnetic field\nin a two-subband GaAs/AlGaAs two-dimensional electron system at filling factor\naround $\\nu=4$. Within a narrow tilting range angle of 0.5 degrees, the\nactivation energy increases as much as 12 K. While the origin of this puzzling\nobservation remains to be exploited, we discuss the possibility of a\nlong-sought pairing state of electrons with a four-fold degeneracy."
    },
    {
        "anchor": "Linear and nonlinear optical properties of multi-layered spherical\n  nano-systems with donor impurity in the center: In this study, the linear, third-order nonlinear and total absorption\ncoefficients (ACs) of multi-layered quantum dot (MLQD) and multi-layered\nquantum anti-dot (MLQAD) with a hydrogenic impurity are calculated. The\nanalytical and numerical solutions of Schr\\\"{o}dinger equation for both MLQD\nand MLQAD, within the effective mass approximation and dielectric continuum\nmodel, are obtained. As our numerical results indicate, an increase in the\noptical intensity changes the total AC considerably, but the intensity range\nthat leads to these changes is different for MLQAD and MLQD. It is observed\nthat by changing the incident photon energy, the AC curves corresponding to\nMLQAD and MLQD are of different shapes and behaviors. The peak heights of AC\ncurves corresponding to MLQAD are strongly affected by changing the core\nantidot radius and the shell thickness values, however in these cases no\nconsiderable changes are observed in peak heights of MLQD. Furthermore, in\ncontrast to MLQAD, the photon energies corresponding to total AC peaks of MLQD\nare more affected by changing the confining potentials (CPs).",
        "positive": "Topological strength of magnetic skyrmions: We deal with magnetic structures that attain integer and half-integer\nskyrmion numbers. We model and solve the problem analytically, and show how the\nsolutions appear in materials that engender distinct, very specific physical\nproperties, and use them to describe their topological features. In particular,\nwe found a way to model skyrmion with a large transition region correlated with\nthe presence of a two-peak skyrmion number density. Moreover, we run into the\nissue concerning the topological strength of a vortex-like structure and\nsuggest an experimental realization, important to decide how to modify and\nmeasure the topological strength of the magnetic structure."
    },
    {
        "anchor": "Effect of impurities in high-symmetry lattice positions on the local\n  density of states and conductivity of graphene: Motivated by quantum chemistry calculations, showing that molecular\nadsorption in graphene takes place on preferential sites of the honeycomb\nlattice, we study the effect of an isolated impurity on the local electronic\nproperties of a graphene monolayer, when the impurity is located on a\nsite-like, bond-like, or hollow-like position. We evaluate the local density of\nstates (LDOS) as a function of energy on the impurity and on its neighboring\nsites, as well as in reciprocal space, at an energy corresponding to a bound\nstate, in the three cases of interest. The latter study may be relevant to\ninterpret the results of Fourier transformed scanning tunneling spectroscopy,\nas they show which states mostly contribute to impurity-induced variations of\nthe LDOS. We also estimate, semi-analytically, the dependence of the condition\nfor having a low-energy bound state on the impurity potential strength and\nwidth. Such results are then exploited to obtain the quasiparticle lifetime and\nthe static conductivity in graphene in the dilute impurity limit. In\nparticular, we recover a sublinear dependence of the conductivity on the\ncarrier concentration as a generic impurity effect.",
        "positive": "Structural studies of silicate glasses with PbS and PbSe nanoparticles: Optical materials with semiconductor nanoparticles within dielectric matrices\nare of interest for construction of non-linear optical elements, selective\nfilters, spectral converters, etc. In the present work, we concern the glasses\nwith PbS and PbSe fabricated by the two-step technique on the basis of silicate\nglass matrix and report the recent studied using the small-angle neutron\nscattering (SANS) technique. A proper understanding the structure of material,\nsize of particles and spectral features need to control optical functionality\nof glasses. SANS is efficient non-destructive technique allowing a wide range\nof structural models in the size range from atomic clusters to submicron size.\nHere we combine SANS measurements with wide-angle X-ray diffraction (WXRD) and\nelectron microscopy to get information on nanoparticles formed in a series of\nPbS and PbSe-doped silicate glasses."
    },
    {
        "anchor": "Reactive-Ion-Etched Graphene Nanoribbons on a Hexagonal Boron Nitride\n  Substrate: We report on the fabrication and electrical characterization of both single\nlayer graphene micron-sized devices and nanoribbons on a hexagonal boron\nnitride substrate. We show that the micron-sized devices have significantly\nhigher mobility and lower disorder density compared to devices fabricated on\nsilicon dioxide substrate in agreement with previous findings. The transport\ncharacteristics of the reactive-ion-etched graphene nanoribbons on hexagonal\nboron nitride, however, appear to be very similar to those of ribbons on a\nsilicon dioxide substrate. We perform a detailed study in order to highlight\nboth similarities as well as differences. Our findings suggest that the edges\nhave an important influence on transport in reactive ion-etched graphene\nnanodevices.",
        "positive": "The influence of vibronic coupling on the shape of transport\n  characteristics in inelastic tunneling through molecules: Here we present theoretical studies of the effect of vibronic coupling on\nnonlinear transport characteristics (current-voltage and conductance-voltage)\nin molecular electronic devices. Considered device is composed of molecular\nquantum dot (with discrete energy levels) weakly connected to metallic\nelectrodes (treated within the wide-band approximation), where molecular\nvibrations are modeled as dispersionless phonon excitations. Nonperturbative\ncomputational scheme, used in this work, is based on the Green's function\ntheory within the framework of mapping technique (GFT-MT) which transforms the\nmany-body electron-phonon interaction problem into a one-body multi-channel\nsingle-electron scattering problem. In particular, it is shown that quantum\ncoherent transport of virtual polarons through the molecule can be a dominant\nfactor justifying some well-known discrepancies between theoretical\ncalculations and experimental results."
    },
    {
        "anchor": "Composite fermions in the Fractional Quantum Hall Effect: Transport at\n  finite wavevector: We consider the conductivity tensor for composite fermions in a close to\nhalf-filled Landau band in the temperature regime where the scattering off the\npotential and the trapped gauge field of random impurities dominates. The\nBoltzmann equation approach is employed to calculate the quasiclassical\ntransport properties at finite effective magnetic field, wavevector and\nfrequency. We present an exact solution of the kinetic equation for all\nparameter regimes. Our results allow a consistent description of recently\nobserved surface acoustic wave resonances and other findings.",
        "positive": "Two-particle scattering and resistivity of Rashba electron gas: We calculate the electrical resistivity of a two-dimensional electron gas\nthat results from two-particle collisions and strong Rashba spin-orbit\ncoupling. In the absence of impurities, two-particle collisions do not\ncontribute to resistivity. When combined with impurity scattering, the\ntwo-particle correction to the resistivity is proportional to the square of\ntemperature $T$ if only the lower helicity band is filled, but the $T^2$ term\nvanishes if the Fermi level is above the Dirac point."
    },
    {
        "anchor": "Transverse NMR relaxation in magnetically heterogeneous media: We consider the NMR signal from a permeable medium with a heterogeneous\nLarmor frequency component that varies on a scale comparable to the\nspin-carrier diffusion length. We focus on the mesoscopic part of the\ntransverse relaxation, that occurs due to dispersion of precession phases of\nspins accumulated during diffusive motion. By relating the spectral lineshape\nto correlation functions of the spatially varying Larmor frequency, we\ndemonstrate how the correlation length and the variance of the Larmor frequency\ndistribution can be determined from the NMR spectrum. We corroborate our\nresults by numerical simulations, and apply them to quantify human blood\nspectra.",
        "positive": "Missing Shapiro steps in topologically trivial Josephson Junction on\n  InAs quantum well: Josephson junctions hosting Majorana fermions have been predicted to exhibit\na 4$\\pi$ periodic current phase relation. The experimental consequence of this\nperiodicity is the disappearance of odd steps in Shapiro steps experiments.\nExperimentally, missing odd Shapiro steps have been observed in a number of\nmaterials systems with strong spin-orbit coupling and have been interpreted in\nthe context of topological superconductivity. Here, we report on missing odd\nsteps in topologically trivial Josephson junctions fabricated on InAs quantum\nwells. We ascribe our observations to the high transparency of our junctions\nallowing Landau-Zener transitions. The probability of these processes is found\nto be independent of the drive frequency. We analyze our results using a\nbi-modal transparency distribution which demonstrates that only few modes\ncarrying 4$\\pi$ periodic current are sufficient to describe the disappearance\nof odd steps. Our findings highlight the elaborate circumstances that have to\nbe considered in the investigation of the 4$\\pi$ Josephson junctions in\nrelationship to topological superconductivity."
    },
    {
        "anchor": "Cleaning Interfaces in Layered Materials Heterostructures: Heterostructures formed by stacking layered materials require atomically\nclean interfaces. However, contaminants are usually trapped between the layers,\naggregating into blisters. We report a process to remove such blisters,\nresulting in clean interfaces. We fabricate blister-free regions of graphene\nencapsulated in hexagonal boron nitride of$\\sim$5000$\\mu $m$^{2}$, limited only\nby the size of the exfoliated flakes. These have mobilities up\nto$\\sim$180000cm$^2$V$^{-1}$s$^{-1}$ at room temperature,\nand$\\sim$1.8$\\times$10$^6$cm$^2$V$^{-1}$s$^{-1}$ at 9K. We further demonstrate\nthe effectiveness of our approach by cleaning heterostructures assembled using\ngraphene intentionally exposed to polymers and solvents. After cleaning, these\nsamples reach similar high mobilities. We also showcase the general\napplicability of our approach to layered materials by cleaning blisters in\nother heterostructures based on MoS$_{2}$. This demonstrates that exposure of\ngraphene to processing-related contaminants is compatible with the realization\nof high mobility samples, paving the way to the development of fab-based\nprocesses for the integration of layered materials in (opto)-electronic\ndevices.",
        "positive": "Interlayer coupling enhancement in graphene/hexagonal boron nitride\n  heterostructures by intercalated defects and vacancies: Among two-dimensional atomic crystals, hexagonal boron nitride (hBN) is one\nof the most remarkable materials to fabricate heterostructures revealing\nunusual properties. We perform first-principles calculations to determine\nwhether intercalated metal atoms and vacancies can mediate interfacial coupling\nand influence the structural and electronic properties of the graphene/hBN\nheterostructure. Metal impurity atoms (Li, K, Cr, Mn, Co, and Cu) as extrinsic\ndefects between the graphene and hBN sheets produce $n$-doped graphene. We also\nconsider intrinsic vacancy defects and find that a boron monovacancy in hBN act\nas a magnetic dopant for graphene whereas a nitrogen monovacancy in hBN serves\nas a nonmagnetic dopant for graphene. In contrast, smallest triangular vacancy\ndefects in hBN are unlikely to result in significant changes in the electronic\ntransport of graphene. Our findings reveal that the hBN layer with some\nvacancies or metal impurities enhance the interlayer coupling in the\ngraphene/hBN heterostructure with respect to charge doping and electron\nscattering."
    },
    {
        "anchor": "Anomalous conductivity of two-dimensional Dirac electrons in organic\n  conductor under pressures: The electric conductivity of Dirac electrons in the organic conductor\n$\\alpha$-(BEDT-TTF)$_2$I$_3$ [BEDT-TTF = bis(ethylenedithio)tetrathiafulvalene]\nunder pressure has been examined using a two-dimensional tight-binding (TB)\nmodel with both impurity and electron--phonon (e--p) scatterings. We study an\nanomalous temperature dependence of the conductivity, which shows a crossover\nfrom $\\sigma_{x} < \\sigma_{y}$ at low temperatures [region (I)] to $\\sigma_{x}\n> \\sigma_{y}$ at high temperatures [region (II)]. $\\sigma_y$ and $\\sigma_x$ are\ndiagonal conductivities parallel and perpendicular to a stacking axis of\nmolecules, respectively. The effect of Dirac cone tilting is dominant in region\n(I), whereas the anisotropy of the velocity of the Dirac cone is dominant in\nregion (II). Such behavior is further examined by calculating the deviation of\nprincipal axes due to the off-diagonal conductivity $\\sigma_{xy}$ and a nearly\nconstant conductivity at high temperatures due to the e--p scattering, which is\nthe extension of the previous result of the simple two-band model [Phys. Rev. B\n{\\bf 98},161205 (2018)]. The relevance to experiments of organic conductors is\ndiscussed.",
        "positive": "Unusual anisotropy of inplane field magnetoresistance in ultra-high\n  mobility SiGe/Si/SiGe quantum wells: We find an unusual anisotropy of the inplane field magnetoresistance in\nultra-high mobility SiGe/Si/SiGe quantum wells. The anisotropy depends on the\norientation between the inplane field, $B_\\parallel$, and current, $I$,\nrelative to the crystallographic axes of the sample and is a consequence of the\nintrinsic ridges on the quantum well surface. For the simplest orientations\nbetween current and crystallographic axes, a method of recalculating the\nmagnetoresistance measured at $I\\perp B_\\parallel$ into the one measured at\n$I\\parallel B_\\parallel$ is suggested and is shown to yield results that agree\nwith the experiment."
    },
    {
        "anchor": "Decoherence and Quantum Measurement of Josephson-Junction Qubits: This work deals with two pressing issues in the design and operation of\nJosephson qubits -- loss of coherence and measurement. (Longer abstract follows\nin the work.)",
        "positive": "All-optical sensing of a single-molecule electron spin: We demonstrate an all-optical method for magnetic sensing of individual\nmolecules in ambient conditions at room temperature. Our approach is based on\nshallow nitrogen-vacancy (NV) centers near the surface of a diamond crystal,\nwhich we use to detect single paramagnetic molecules covalently attached to the\ndiamond surface. The manipulation and readout of the NV centers is all-optical\nand provides a sensitive probe of the magnetic field fluctuations stemming from\nthe dynamics of the electronic spins of the attached molecules. As a specific\nexample, we demonstrate detection of a single paramagnetic molecule containing\na gadolinium (Gd$^{3+}$) ion. We confirm single-molecule resolution using\noptical fluorescence and atomic force microscopy to co-localize one NV center\nand one Gd$^{3+}$-containing molecule. Possible applications include nanoscale\nand in vivo magnetic spectroscopy and imaging of individual molecules."
    },
    {
        "anchor": "Electrical detection of magnetic states in crossed nanowires using the\n  topological Hall effect: We used micromagnetic simulations to investigate the spatial distributions of\nthe effective magnetic fields induced by spin chirality in crossed nanowires\nwith three characteristic magnetic structures: a radiated-shape, an antivortex,\nand a uniform-like states. Our results indicate that, unlike the anomalous Hall\neffect, the topological Hall effect (which is related to the spin chirality)\ndepends on both the polarity and the vorticity. Therefore, measuring the\ntopological Hall effect can detect both the polarity and the vorticity\nsimultaneously in crossed nanowires. This approach may be suitable for use as\nan elemental technique in the quest for a next-generation multi-value memory.",
        "positive": "Double Free-Layer Magnetic Tunnel Junctions for Probabilistic Bits: Naturally random devices that exploit ambient thermal noise have recently\nattracted attention as hardware primitives for accelerating probabilistic\ncomputing applications. One such approach is to use a low barrier nanomagnet as\nthe free layer of a magnetic tunnel junction (MTJ) whose magnetic fluctuations\nare converted to resistance fluctuations in the presence of a stable fixed\nlayer. Here, we propose and theoretically analyze a magnetic tunnel junction\nwith no fixed layers but two free layers that are circularly shaped disk\nmagnets. We use an experimentally benchmarked model that accounts for finite\ntemperature magnetization dynamics, bias-dependent charge and spin-polarized\ncurrents as well as the dipolar coupling between the free layers. We obtain\nanalytical results for statistical averages of fluctuations that are in good\nagreement with the numerical model. We find that the free layers with low\ndiameters fluctuate to randomize the resistance of the MTJ in an approximately\nbias-independent manner. We show how such MTJs can be used to build a binary\nstochastic neuron (or a p-bit) in hardware. Unlike earlier stochastic MTJs that\nneed to operate at a specific bias point to produce random fluctuations, the\nproposed design can be random for a wide range of bias values, independent of\nspin-transfer-torque pinning. Moreover, in the absence of a carefully optimized\nstabled fixed layer, the symmetric double-free layer stack can be manufactured\nusing present day Magnetoresistive Random Access Memory (MRAM) technology by\nminimal changes to the fabrication process. Such devices can be used as\nhardware accelerators in energy-efficient computing schemes that require a\nlarge throughput of tunably random bits."
    },
    {
        "anchor": "The Quantum Skin Hall Effect: The skin effect, which is unique to non-Hermitian systems, can generate an\nextensive number of eigenstates localized near the boundary in an open\ngeometry. Here we propose that in 2D and 3D other quantities besides charge\ndensity are susceptible to the skin effect. We show that 2D and 3D models that\nare a hybrid between topological insulators and skin-effect systems can have a\ntopological skin effect where an extensive number of topological modes, and the\ncorresponding bulk topological invariant, are pinned to the surface. A key\nexample, which we call the quantum skin Hall effect is constructed from layers\nof Chern insulators and exhibits an extensive Hall conductance and number of\nchiral modes bound to surfaces normal to the stack of layers. The same\nprocedure is further extended to other symmetry classes to illustrate that a\nvariety of 1D and 2D topological invariants ($\\mathbb{Z}$ or $\\mathbb{Z}_2)$\nare subject to the skin effect. Indeed, we also propose a hybrid 2D system that\nexhibits an extensive number of topological corner modes and may be more easily\nrealized in meta-material experiments.",
        "positive": "Thermally driven spin injection from a ferromagnet into a non-magnetic\n  metal: Creating, manipulating and detecting spin polarized carriers are the key\nelements of spin based electronics. Most practical devices use a perpendicular\ngeometry in which the spin currents, describing the transport of spin angular\nmomentum, are accompanied by charge currents. In recent years, new sources of\npure spin currents, i.e., without charge currents, have been demonstrated and\napplied. In this paper, we demonstrate a conceptually new source of pure spin\ncurrent driven by the flow of heat across a ferromagnetic/non-magnetic metal\n(FM/NM) interface. This spin current is generated because the Seebeck\ncoefficient, which describes the generation of a voltage as a result of a\ntemperature gradient, is spin dependent in a ferromagnet. For a detailed study\nof this new source of spins, it is measured in a non-local lateral geometry. We\ndeveloped a 3D model that describes the heat, charge and spin transport in this\ngeometry which allows us to quantify this process. We obtain a spin Seebeck\ncoefficient for Permalloy of -3.8 microvolt/Kelvin demonstrating that thermally\ndriven spin injection is a feasible alternative for electrical spin injection\nin, for example, spin transfer torque experiments."
    },
    {
        "anchor": "High-Q Nanomechanics via Destructive Interference of Elastic Waves: Mechanical dissipation poses an ubiquitous challenge to the performance of\nnanomechanical devices. Here we analyze the support-induced dissipation of\nhigh-stress nanomechanical resonators. We develop a model for this loss\nmechanism and test it on silicon nitride membranes with circular and square\ngeometries. The measured Q-values of different harmonics present a\nnon-monotonic behavior which is successfully explained. For azimuthal harmonics\nof the circular geometry we predict that destructive interference of the\nradiated waves leads to an exponential suppression of the clamping loss in the\nharmonic index. Our model can also be applied to graphene drums under high\ntension.",
        "positive": "Exciton propagation and halo formation in two-dimensional materials: The interplay of optics, dynamics and transport is crucial for the design of\nnovel optoelectronic devices, such as photodetectors and solar cells. In this\ncontext, transition metal dichalcogenides (TMDs) have received much attention.\nHere, strongly bound excitons dominate optical excitation, carrier dynamics and\ndiffusion processes. While the first two have been intensively studied, there\nis a lack of fundamental understanding of non-equilibrium phenomena associated\nwith exciton transport that is of central importance e.g. for high efficiency\nlight harvesting. In this work, we provide microscopic insights into the\ninterplay of exciton propagation and many-particle interactions in TMDs. Based\non a fully quantum mechanical approach and in excellent agreement with\nphotoluminescence measurements, we show that Auger recombination and emission\nof hot phonons act as a heating mechanism giving rise to strong spatial\ngradients in excitonic temperature. The resulting thermal drift leads to an\nunconventional exciton diffusion characterized by spatial exciton halos."
    },
    {
        "anchor": "Phase signature of topological transition in Josephson Junctions: Topological superconductivity holds promise for fault-tolerant quantum\ncomputing. While planar Josephson junctions are attractive candidates to\nrealize this exotic state, direct phase-measurements as the fingerprint of the\ntopological transition are missing. By embedding two gate-tunable Al/InAs\nJosephson junctions in a loop geometry, we measure a $\\pi$-jump in the junction\nphase with increasing in-plane magnetic field, ${\\bf B}_\\|$. This jump is\naccompanied by a minimum of the critical current, indicating a closing and\nreopening of the superconducting gap, strongly anisotropic in ${\\bf B}_\\|$. Our\ntheory confirms that these signatures of a topological transition are\ncompatible with the emergence of Majorana states.",
        "positive": "Transport Spectroscopy of Symmetry-Broken Insulating States in Bilayer\n  Graphene: The flat bands in bilayer graphene(BLG) are sensitive to electric fields\nE\\bot directed between the layers, and magnify the electron-electron\ninteraction effects, thus making BLG an attractive platform for new\ntwo-dimensional (2D) electron physics[1-5]. Theories[6-16] have suggested the\npossibility of a variety of interesting broken symmetry states, some\ncharacterized by spontaneous mass gaps, when the electron-density is at the\ncarrier neutrality point (CNP). The theoretically proposed gaps[6,7,10] in\nbilayer graphene are analogous[17,18] to the masses generated by broken\nsymmetries in particle physics and give rise to large momentum-space Berry\ncurvatures[8,19] accompanied by spontaneous quantum Hall effects[7-9]. Though\nrecent experiments[20-23] have provided convincing evidence of strong\nelectronic correlations near the CNP in BLG, the presence of gaps is difficult\nto establish because of the lack of direct spectroscopic measurements. Here we\npresent transport measurements in ultra-clean double-gated BLG, using\nsource-drain bias as a spectroscopic tool to resolve a gap of ~2 meV at the\nCNP. The gap can be closed by an electric field E\\bot \\sim13 mV/nm but\nincreases monotonically with a magnetic field B, with an apparent particle-hole\nasymmetry above the gap, thus providing the first mapping of the ground states\nin BLG."
    },
    {
        "anchor": "Theory of oscillations in the STM conductance resulting from subsurface\n  defects (Review Article): In this review we present recent theoretical results concerning\ninvestigations of single subsurface defects by means of a scanning tunneling\nmicroscope (STM). These investigations are based on the effect of quantum\ninterference between the electron partial waves that are directly transmitted\nthrough the contact and the partial waves scattered by the defect. In\nparticular, we have shown the possibility imaging the defect position below a\nmetal surface by means of STM. Different types of subsurface defects have been\ndiscussed: point-like magnetic and non-magnetic defects, magnetic clusters in a\nnonmagnetic host metal, and non-magnetic defects in a s-wave superconductor.\nThe effect of Fermi surface anisotropy has been analyzed. Also, results of\ninvestigations of the effect of a strong magnetic field to the STM conductance\nof a tunnel point contact in the presence of a single defect has been\npresented.",
        "positive": "Designing spin-textured flat bands in twisted graphene multilayers via\n  helimagnet encapsulation: Twisted graphene multilayers provide tunable platforms to engineer flat bands\nand exploit the associated strongly correlated physics. The two-dimensional\nnature of these systems makes them suitable for encapsulation by materials that\nbreak specific symmetries. In this context, recently discovered two-dimensional\nhelimagnets, such as the multiferroic monolayer NiI$_2$, are specially\nappealing for breaking time-reversal and inversion symmetries due to their\nnontrivial spin textures. Here we show that this spin texture can be imprinted\non the electronic structure of twisted bilayer graphene by proximity effect. We\ndiscuss the dependence of the imprinted spin texture on the wave-vector of the\nhelical structure, and on the strength of the effective local exchange field.\nBased on these results we discuss the nature of the superconducting\ninstabilities that can take place in helimagnet encapsulated twisted bilayer\ngraphene. Our results put forward helimagnetic encapsulation as a powerful way\nof designing spin-textured flat band systems, providing a starting point to\nengineer a new family of correlated moire states."
    },
    {
        "anchor": "Quantum electrodynamic approach to the conductivity of gapped graphene: The electrical conductivity of graphene with a nonzero mass-gap parameter is\ninvestigated starting from the first principles of quantum electrodynamics in\n(2+1)-dimensional space-time at any temperature. The formalism of the\npolarization tensor defined over the entire plane of complex frequency is used.\nAt zero temperature we reproduce the results for both real and imaginary parts\nof the conductivity, obtained previously in the local approximation, and\ngeneralize them taking into account the effects of nonlocality. At nonzero\ntemperature the exact analytic expressions for real and imaginary parts of the\nlongitudinal and transverse conductivities of gapped graphene are derived, as\nwell as their local limits and approximate expressions in several asymptotic\nregimes. Specifically, a simple local result for the real part of conductivity\nof gapped graphene valid at any temperature is obtained. According to our\nresults, the real part of the conductivity is not equal to zero for frequencies\nexceeding the width of the gap and goes to the universal conductivity with\nincreasing frequency. The imaginary part of conductivity of gapped graphene\nvaries from infinity at zero frequency to minus infinity at the frequency\ndefined by the gap parameter and then goes to zero with further increase of\nfrequency. The analytic expressions are accompanied by the results of numerical\ncomputations. Possible future generalization of the used formalism is\ndiscussed.",
        "positive": "Large conductance modulation of gold thin films by huge charge injection\n  via electrochemical gating: By using an electrochemical gating technique with a new combination of\npolymer and electrolyte, we were able to inject surface charge densities n_2D\nas high as 3.5 \\times 10^15 e/cm^2 in gold films and to observe large relative\nvariations in the film resistance, DeltaR/R', up to 10% at low temperature.\nDeltaR/R' is a linear function of n_2D - as expected within a free-electron\nmodel - if the film is thick enough (> 25 nm), otherwise a tendency to\nsaturation due to size effects is observed. The application of this technique\nto 2D materials will allow extending the field-effect experiments to a range of\ncharge doping where giant conductance modulations and, in some cases, even the\noccurrence of superconductivity are expected."
    },
    {
        "anchor": "Two-body problem in graphene: We study the problem of two Dirac particles interacting through\nnon-relativistic potentials and confined to a two-dimensional sheet, which is\nthe relevant case for graphene layers. The two-body problem cannot be mapped\ninto that of a single particle, due to the non-trivial coupling between the\ncenter-of-mass and the relative coordinates, even in the presence of central\npotentials. We focus on the case of zero total momentum, which is equivalent to\nthat of a single particle in a Sutherland lattice. We show that zero-energy\nstates induce striking new features such as discontinuities in the relative\nwave function, for particles interacting through a step potential, and a\nconcentration of relative density near the classical turning point, if\nparticles interact via a Coulomb potential. In the latter case we also find\nthat the two-body system becomes unstable above a critical coupling. These\nphenomena may have bearing on the nature of strong coupling phases in graphene.",
        "positive": "Majorana qubit decoherence by quasiparticle poisoning: We consider the problem of quasiparticle poisoning in a nanowire-based\nrealization of a Majorana qubit, where a spin-orbit-coupled semiconducting wire\nis placed on top of a (bulk) superconductor. By making use of recent\nexperimental data exhibiting evidence of a low-temperature residual\nnon-equilibrium quasiparticle population in superconductors, we show by means\nof analytical and numerical calculations that the dephasing time due to the\ntunneling of quasiparticles into the nanowire may be problematically short to\nallow for qubit manipulation."
    },
    {
        "anchor": "Pulsed-gate measurements of the singlet-triplet relaxation time in a\n  two-electron double quantum dot: A pulsed-gate technique with charge sensing is used to measure the\nsinglet-triplet relaxation time for nearly-degenerate spin states in a\ntwo-electron double quantum dot. Transitions from the (1,1) charge occupancy\nstate to the (0,2) state, measured as a function of pulse cycle duration and\nmagnetic field, allow the (1,1) singlet-triplet relaxation time (~70\nmicroseconds) and the (0,2) singlet-triplet splitting to be measured. The use\nof charge sensing rather than current measurement allows long relaxation times\nto be readily probed.",
        "positive": "Casimir Interactions Between Scatterers in Metallic Carbon Nanotubes: We study interactions between localized scatterers on metallic carbon\nnanotubes by a mapping onto a one-dimensional Casimir problem. Backscattering\nof electrons between localized scattering potentials mediates long range forces\nbetween them. We model spatially localized scatterers by local and non-local\npotentials and treat simultaneously the effects of intravalley and intervalley\nbackscattering. We find that the long range forces between scatterers exhibit\nthe universal power law decay of the Casimir force in one dimension, with\nprefactors that control the sign and strength of the interaction. These\nprefactors are nonuniversal and depend on the symmetry and degree of\nlocalization of the scattering potentials. We find that local potentials\ninevitably lead to a coupled valley scattering problem, though by contrast\nnon-local potentials lead to two decoupled single-valley problems in a\nphysically realized regime. The Casimir effect due to two-valley scattering\npotentials is characterized by the appearance of spatially periodic modulations\nof the force."
    },
    {
        "anchor": "Multiscale approach to spin transport in magnetic multilayers: This article discusses two dual approaches to spin transport in magnetic\nmultilayers: a direct, purely quantum, approach based on a Tight-Biding model\n(TB) and a semiclassical approach (Continuous Random Matrix Theory, CRMT). The\ncombination of both approaches provides a systematic way to perform\nmulti-scales simulations of systems that contain relevant physics at scales\nlarger (spin accumulation, spin diffusion...) and smaller (specular reflexions,\ntunneling...) than the elastic mean free paths of the layers. We show\nexplicitly that CRMT and TB give consistent results in their common domain of\napplicability.",
        "positive": "Ratchet effect in graphene with trigonal clusters: In this study, we explore the ratchet effect in graphene with artificial,\ntriangular scatterers from a theoretical standpoint. It is demonstrated that\nthe skew scattering of carriers by such coherently oriented defects results in\nthe ratchet effect in graphene, i.e., in a direct current under the action of\nan oscillating electric field. Scattering on various types of defects\nexhibiting threefold symmetry is considered in this paper: scattering on a\ncluster in the shape of a solid triangle in the classical and quantum\nmechanical limits, and scattering on three- point defects placed at the corners\nof a triangle. The DC current is calculated for a classical range of\noscillating field frequencies."
    },
    {
        "anchor": "Probing Purcell enhancement and photon collection efficiency of InAs\n  quantum dots at nodes of the cavity electric field: The interaction of excitonic transitions with confined photonic modes enables\ntests of quantum physics and design of efficient optoelectronic devices. Here\nwe study how key metrics such as Purcell factor, beta-factor and collection\nefficiency are determined by the non-cavity modes which exist in real devices,\ntaking the well-studied micropillar cavity as an example. Samples with dots at\ndifferent positions in the cavity field allow us to quantify the effect of the\nnon-cavity modes and show that the zero-phonon line and the phonon-assisted\nemission into the cavity mode HE11 is suppressed by positioning dots at the\nfield node.",
        "positive": "Extreme Near-Field Heat Transfer Between Gold Surfaces: Extreme near-field heat transfer between metallic surfaces is a subject of\ndebate as the state-of-the-art theory and experiments are in disagreement on\nthe energy carriers driving heat transport. In an effort to elucidate the\nphysics of extreme near-field heat transfer between metallic surfaces, this\nLetter presents a comprehensive model combining radiation, acoustic phonon and\nelectron transport across sub-10-nm vacuum gaps. The results obtained for gold\nsurfaces show that in the absence of bias voltage, acoustic phonon transport is\ndominant for vacuum gaps smaller than ~2 nm. The application of a bias voltage\nsignificantly affects the dominant energy carriers as it increases the phonon\ncontribution mediated by the long-range Coulomb force and the electron\ncontribution due to a lower potential barrier. For a bias voltage of 0.6 V,\nacoustic phonon transport becomes dominant at a vacuum gap of 5 nm, whereas\nelectron tunneling dominates at sub-1-nm vacuum gaps. The comparison of the\ntheory against experimental data from the literature suggests that\nwell-controlled measurements between metallic surfaces are needed to quantify\nthe contributions of acoustic phonon and electron as a function of the bias\nvoltage."
    },
    {
        "anchor": "Faraday effect optical sensing of single-molecules by graphene-based\n  layered structures: Recently, modulation of the energy bandgap of graphene when gas molecules are\nadsorbed to its surface has been proved to be possible. Motivated by this,\nbased on numerical calculations, we investigate the effect of the associated\nbandgap opening in graphene's spectrum on the sensing properties of the Faraday\nrotation (FR) of linearly polarized electromagnetic modes in a 1D photonic\ngraphene-based sensor with a microcavity defect channel covered by two graphene\nlayers. Our proposed model introduces an optical contact-free mechanism for the\ndetection of low-concentration molecules attached to graphene's surface. We\nalso show that FR angles could reveal reversal signs for a different amount of\nsurface transfer doping.",
        "positive": "On the ground state of a completely filled lowest Landau level in two\n  dimensions: There exists a widely believed opinion, that the many-body ground state of a\ntwo-dimensional electron system at a completely filled lowest Landau level (the\nfilling factor $\\nu=1$) is described by the so-called Hartree-Fock wave\nfunction, and that this solution is the unique, exact eigenstate of the system\nat $\\nu=1$. I show that this opinion is erroneous, construct an infinite number\nof other variational many-body wave functions, and discuss the properties of a\nfew states which have the energy substantially lower than the energy of the\nHartree-Fock state."
    },
    {
        "anchor": "Pressure induced gap modulation and topological transitions in twisted\n  bilayer and double bilayer graphene: We study the electronic and topological properties of fully relaxed twisted\nbilayer (TBG) and double bilayer (TDBG) graphene under perpendicular pressure.\nAn approach has been proposed to obtain the equilibrium in-plane structural\ndeformation and out-of-plane corrugation in moir\\'{e} superlattices under\npressure. We find that the in-plane relaxation becomes much stronger under\nhigher pressure, while the corrugation height in each layer is maintained. The\ncomparison between band structures of relaxed and rigid structures demonstrates\nthat not only the gaps on the electron and hole sides ($\\Delta_e$ and\n$\\Delta_h$) are significantly underestimated without relaxation but also the\ndetailed dispersions of the middle bands of rigid structures are rather\ndifferent from those of relaxed systems. $\\Delta_e$ and $\\Delta_h$ in TBG reach\nmaximum values around critical pressures with narrowest middle bands.\nTopological transitions occur in TDBG under pressure with the middle valence\nand conduction bands in one valley touching and their Chern numbers transferred\nto each other. The pressure can also tune the gap at the neutrality point of\nTDBG, which becomes closed for a pressure range and reopened under higher\npressure. The behavior of electronic structure of supertlattices under pressure\nis sensitive to the twist angle $\\theta$ with the critical pressures generally\nincrease with $\\theta$.",
        "positive": "Quantum yield optimized fluorophores for site-specific labeling and\n  super-resolution imaging: Single molecule applications, saturated pattern excitation microscopy, or\nstimulated emission depletion (STED) microscopy demand for bright and highly\nstable fluorescent dyes1,2. Despite of intensive research the choice of\nfluorphores is still very limited. Typically a stable fluorescent dyes is\ncovalently attached to the target. This methodology brings forward a number of\nlimitations, in particular, in case of protein labeling. First of all the\nfluorescent probes need to be attached selectively and site-specifically to\nprevent unspecific background. This often requires single cysteine mutations\nfor covalent protein modification. Employing quantum dots allows overcoming\nproblems of photo-bleaching3-6. However, the downsides are their large size,\nrendering the probe inaccessible to spatially confined architectures, issues in\nbiocompatibility due to proper particle coating, and cellular toxicity6-8. Here\nwe propose a new method to overcome the above outlined problems."
    },
    {
        "anchor": "Demonstration of a polariton step potential by local variation of\n  light-matter coupling in a van-der-Waals heterostructure: The large oscillator strength of excitons in transition metal dichalcogenide\nlayers facilitates the formation of exciton-polariton resonances for monolayers\nand van-der-Waals heterostructures embedded in optical microcavities. Here, we\nshow, that locally changing the number of layers in a WSe2/hBN/WSe2\nvan-der-Waals heterostructure embedded in a monolithic, high-quality-factor\ncavity gives rise to a local variation of the coupling strength. This effect\nyields a polaritonic stair case potential, which we demonstrate at room\ntemperature. Our result paves the way towards engineering local polaritonic\npotentials at length scales down to atomically sharp interfaces, based on\npurely modifying its real part contribution via the coherent light-matter\ncoupling strength g.",
        "positive": "Central role of domain wall depinning for perpendicular magnetization\n  switching driven by spin torque from the spin Hall effect: We study deterministic magnetic reversal of a perpendicularly magnetized Co\nlayer in a Co/MgO/Ta nano-square driven by spin Hall torque from an in-plane\ncurrent flowing in an underlying Pt layer. The rate-limiting step of the\nswitching process is domain-wall (DW) depinning by spin Hall torque via a\nthermally-assisted mechanism that eventually produces full reversal by domain\nexpansion. An in-plane applied magnetic field collinear with the current is\nrequired, with the necessary field scale set by the need to overcome DW\nchirality imposed by the Dzyaloshinskii-Moriya interaction. Once Joule heating\nis taken into account the switching current density is quantitatively\nconsistent with a spin Hall angle {\\theta}$_{SH}$ ${\\approx}$ 0.07 for 4 nm of\nPt."
    },
    {
        "anchor": "Spin-orbit interaction in Pt or Bi2Te3 nanoparticle-decorated graphene\n  realized by a nanoneedle method: The introduction of spin-orbit interactions (SOIs) and the subsequent\nappearance of a two-dimensional (2D) topological phase are crucial for\nvoltage-controlled and zero-emission energy spintronic devices. In contrast,\ngraphene basically lacks SOIs due to the small mass of the carbon atom, and\nappropriate experimental reports for SOIs are rare. Here, we control\nsmall-amount (cover ratios < 8%) random decoration of heavy nanoparticles\n[platinum (Pt) or bismuth telluride (Bi2Te3)] onto mono-layer graphene by\ndeveloping an original nanoneedle method. X-ray photoelectron spectra support\nlow-damage and low-contamination decoration of the nanoparticles, suggesting\nthe presence of Bi-C and Te-C coupling orbitals. In the samples, we find\nparticle-density-dependent non-local resistance (RNL) peaks, which are\nattributed to the (inverse) spin Hall effect (SHE) arising from SOI with\nenergies as large as about 30 meV. This is a larger value than in previous\nreports and supported by scanning tunneling spectroscopy. The present\nobservation should lead to topological phases of graphene, which can be\nintroduced by random decoration with controlled small amounts of heavy\nnanoparticles, and their applications.",
        "positive": "Inversion symmetry protected topological insulators and superconductors: Three dimensional topological insulator represents a class of novel quantum\nphases hosting robust gapless boundary excitations, which is protected by\nglobal symmetries such as time reversal, charge conservation and spin\nrotational symmetry. In this work we systematically study another class of\ntopological phases of weakly interacting electrons protected by spatial\ninversion symmetry, which generally don't support stable gapless boundary\nstates. We classify these inversion-symmetric topological insulators and\nsuperconductors in the framework of K-theory, and construct their lattice\nmodels. We also discuss quantized response functions of these\ninversion-protected topological phases, which serve as their experimental\nsignatures."
    },
    {
        "anchor": "Impact of strain on the optical fingerprint of monolayer transition\n  metal dichalcogenides: Strain presents a straightforward tool to tune electronic properties of\natomically thin nanomaterials that are highly sensitive to lattice\ndeformations. While the influence of strain on the electronic band structure\nhas been intensively studied, there are only few works on its impact on optical\nproperties of monolayer transition metal dichalcogenides (TMDs). Combining\nmicroscopic theory based on Wannier and Bloch equations with nearestneighbor\ntight-binding approximation, we present an analytical view on how uni- and\nbiaxial strain influences the optical fingerprint of TMDs including their\nexcitonic binding energy, oscillator strength, optical selection rules, and the\nradiative broadening of excitonic resonances. We show that the impact of strain\ncan be reduced to changes in the lattice structure (geometric effect) and in\nthe orbital functions (overlap effect). In particular, we demonstrate that the\nvalley-selective optical selection rule is softened in the case of uniaxial\nstrain due to the introduced asymmetry in the lattice structure. Furthermore,\nwe reveal a considerable increase of the radiative dephasing due to\nstrain-induced changes in the optical matrix element and the excitonic wave\nfunctions.",
        "positive": "Correlated anomalous phase diffusion of coupled phononic modes in a\n  side-band driven resonator: The dynamical backaction from a periodically driven optical or microwave\ncavity can reduce the damping of a mechanical resonator, leading to parametric\ninstability accompanied by self-sustained oscillations. Fundamentally, the\ndriving breaks the continuous time-translation symmetry and replaces it with\nthe symmetry with respect to time translation by the driving period. This\ndiscrete symmetry should be reflected in the character of the oscillations.\nHere, we perform experimental and theoretical study of new aspects of the\nbackaction and the discrete time-translation symmetry using a micromechanical\nresonator designed to have two nonlinearly coupled vibrational modes with\nstrongly differing frequencies and decay rates. We find that self-sustained\noscillations are induced not only in the low frequency mode as measured in\nprevious experiments, but also in the high frequency mode. The vibration\nfrequencies and amplitudes are determined by the system nonlinearity, which\nalso leads to bistability and hysteresis. A remarkable consequence of the\ndiscrete time-translation symmetry is revealed by studying the vibration\nphases. We find that the phase fluctuations of the two modes are nearly\nperfectly anti-correlated. At the same time, in each mode the phase undergoes\nanomalous diffusion, where the time dependence of the phase variance follows a\nsuperlinear rather than the standard linear power law. Our analysis shows that\nthe exponent of the power law is determined by the exponent of the 1/f-type\nintrinsic frequency noise of the resonator. We demonstrate the possibility of\ncompensating for these fluctuations using a feedback scheme to generate stable\noscillations that could prove useful in frequency standards and resonant\ndetection."
    },
    {
        "anchor": "Tunneling Plasmonics in Bilayer Graphene: We report experimental signatures of plasmonic effects due to electron\ntunneling between adjacent graphene layers. At sub-nanometer separation, such\nlayers can form either a strongly coupled bilayer graphene with a Bernal\nstacking or a weakly coupled double-layer graphene with a random stacking\norder. Effects due to interlayer tunneling dominate in the former case but are\nnegligible in the latter. We found through infrared nano-imaging that bilayer\ngraphene supports plasmons with a higher degree of confinement compared to\nsingle- and double-layer graphene, a direct consequence of interlayer\ntunneling. Moreover, we were able to shut off plasmons in bilayer graphene\nthrough gating within a wide voltage range. Theoretical modeling indicates that\nsuch a plasmon-off region is directly linked to a gapped insulating state of\nbilayer graphene: yet another implication of interlayer tunneling. Our work\nuncovers essential plasmonic properties in bilayer graphene and suggests a\npossibility to achieve novel plasmonic functionalities in graphene few-layers.",
        "positive": "Phononic thermal transport along graphene grain boundaries: We reveal that phononic thermal transport in graphene is not immune to grain\nboundaries (GBs) aligned along the direction of the temperature gradient.\nNon-equilibrium molecular dynamics simulations uncover a large reduction in the\nphononic thermal conductivity ($\\kappa_p$) along linear ultra-narrow GBs\ncomprising periodically-repeating pentagon-heptagon dislocations. Green's\nfunction calculations and spectral energy density analysis indicate that\n$\\kappa_p$ is the complex manifestation of the periodic strain field, which\nbehaves as a reflective diffraction grating with both diffuse and specular\nphonon reflections, and represents a source of anharmonic phonon-phonon\nscattering. Our findings provide new insights into the integrity of the\nphononic thermal transport in GB graphene."
    },
    {
        "anchor": "Effects of a uniform magnetic field on twisted graphene nanoribbons: In the present work, the relativistic quantum motion of massless fermions in\na helicoidal graphene nanoribbon under the influence of a uniform magnetic\nfield is investigated. Considering a uniform magnetic field ($B$) aligned along\nthe axis of helicoid, this problem is explored in the context of Dirac equation\nin a curved space-time. As this system does not support exact solutions due to\nconsidered background, the bound-state solutions and local density of state\n(LDOS) are obtained numerically by means of the Numerov method. The combined\neffects of width of the nanoribbon ($D$), length of ribbon ($L$), twist\nparameter ($\\omega$) and $B$ on the equations of motion and local density of\nstates (LDOS) are analyzed and discussed. It is verified that the presence of\n$B$ produces a constant minimum value of local density of state on the axis of\nhelicoid, which is possible only for values large enough of $\\omega$, in\ncontrast to the case for $B=0$ already studied in the literature.",
        "positive": "First-principles calculation of orbital Hall effect by Wannier\n  interpolation: Role of orbital dependence of the anomalous position: The position operator in a Bloch representation acquires a gauge correction\nin the momentum space on top of the canonical position, which is called the\nanomalous position. We show that the anomalous position is generally\norbital-dependent and thus plays a crucial role in the description of the\nintrinsic orbital Hall effect in terms of Wannier basis. We demonstrate this\nfrom the first-principles calculation of orbital Hall conductivities of\ntransition metals by Wannier interpolation. Our results show that consistent\ntreatment of the velocity operator by adding the additional term originating\nfrom the anomalous position predicts the orbital Hall conductivities different\nfrom those obtained by considering only the group velocity. We find the\ndifference is crucial in several metals. For example, we predict the negative\nsign of the orbital Hall conductivities for elements in the groups X and XI\nsuch as Cu, Ag, Au, and Pd, for which the previous studies predicted the\npositive sign. Our work suggests the importance of consistently describing the\nspatial dependence of basis functions by first-principles methods as it is\nfundamentally missing in the tight-binding approximation."
    },
    {
        "anchor": "To close or not to close: the fate of the superconducting gap across the\n  topological quantum phase transition in Majorana-carrying semiconductor\n  nanowires: We investigate theoretically the low energy physics of semiconductor Majorana\nwires in the vicinity of a magnetic field-driven topological quantum phase\ntransition (TQPT). The local density of states (LDOS) at the end of the wire,\nwhich is directly related to the differential conductance in the limit of\npoint-contact tunneling, is calculated numerically. We find that the dependence\nof the end-of-wire LDOS on the magnetic field is non-universal and that the\nsignatures associated with the closing of the superconducting gap at the\nMajorana TQPT are essentially invisible within a significant range of\nexperimentally relevant parameters. Our results provide an explanation for the\nrecent observation of the apparent non-closure of the gap at the Majorana TQPT\nin semiconductor nanowires.",
        "positive": "Laser-induced quantum pumping in graphene: We investigate non-adiabatic electron pumping in graphene generated by laser\nirradiation with linear polarization parallel or perpendicular to the transport\ndirection. Transport is dominated by the spatially asymmetric excitation of\nelectrons from evanescent into propagating modes. For a laser with parallel\npolarization, the pumping response exhibits a subharmonic resonant enhancement\nwhich directly probes the Fermi energy; no such enhancement occurs for\nperpendicular polarization. The resonance mechanism relies on the chirality of\ncharge carriers in graphene."
    },
    {
        "anchor": "Formation of N\u00e9el Type Skyrmions in an Antidot Lattice with\n  Perpendicular Magnetic Anisotropy: Magnetic skyrmions are particle-like chiral spin textures found in a magnetic\nfilm with out-of-planeanisotropy and are considered to be potential candidates\nas information carriers in next generationdata storage devices. Despite intense\nresearch into the nature of skyrmions and their dynamic prop-erties, there are\nseveral key challenges that still need to be addressed. In particular, the\noutstandingissues are the reproducible generation, stabilization and\nconfinement of skyrmions at room tempera-ture. Here, we present a method for\nthe capture of nanometer sized magnetic skyrmions in an arrayof magnetic\ntopological defects in the form of an antidot lattice. With micromagnetic\nsimulations,we elucidate the skyrmion formation in the antidot lattice and show\nthat the capture is dependenton the antidot lattice parameters. This behavior\nis confirmed with scanning transmission x-ray mi-croscopy measurements. This\ndemonstration that a magnetic antidot lattice can be implemented asa host to\ncapture skyrmions provides a new platform for experimental investigations of\nskyrmionsand skyrmion based devices.",
        "positive": "Keldysh approach to the renormalization group analysis of the disordered\n  electron liquid: We present a Keldysh nonlinear sigma-model approach to the renormalization\ngroup analysis of the disordered electron liquid. We include both the Coulomb\ninteraction and Fermi-liquid type interactions in the singlet and triplet\nchannels into the formalism. Based on this model, we reproduce the coupled\nrenormalization group equations for the diffusion coefficient, the frequency,\nand interaction constants previously derived with the replica model in the\nimaginary time technique. With the help of source fields coupling to the\nparticle-number and spin densities, we study the density-density and spin\ndensity-spin density correlation functions in the diffusive regime. This allows\nus to obtain results for the electric conductivity and the spin susceptibility\nand thereby to re-derive the main results of the one-loop renormalization group\nanalysis of the disordered electron liquid in the Keldysh formalism."
    },
    {
        "anchor": "Doping Induced Second Harmonic Generation in Centrosymmetric Graphene\n  from Quadrupole Response: For centrosymmetric materials such as monolayer graphene, no optical second\nharmonic generation (SHG) is generally expected because it is forbidden under\nthe electric-dipole approximation. Yet we observed a strong, doping induced SHG\nfrom graphene, with its highest strength comparable to the electric-dipole\nallowed SHG in non-centrosymmetric 2D materials. This novel SHG has the nature\nof an electric-quadrupole response, arising from the effective breaking of\ninversion symmetry by optical dressing with an in-plane photon wave vector.\nMore remarkably, the SHG is widely tuned by carrier doping or chemical\npotential, being sharply enhanced at Fermi edge resonances, but vanishing at\nthe charge neutral point that manifests the electron-hole symmetry of massless\nDirac Fermions. The striking behavior in graphene, which should also arise in\ngraphene-like Dirac materials, expands the scope of nonlinear optics, and holds\nthe promise of novel optoelectronic and photonic applications.",
        "positive": "Transport in quantum wires with impurities at finite temperatures: The temperature dependence of Coulomb blockade peaks of a one dimensional\nquantum dot is calculated. The Coulomb interaction is treated microscopically\nusing the Luttinger liquid model. The electron interaction is assumed to be\nnon-homogeneous with a maximum strength near the quantum dot. The conductance\npeaks show non-analytic power law behaviour induced by the interaction. It is\nshown that there is a crossover in the power law which is related to the\ninhomogeneity of the interaction."
    },
    {
        "anchor": "Quantum phases of interacting electrons in three-dimensional dirty Dirac\n  semimetals: We theoretically study the stability of three dimensional Dirac semimetals\nagainst short-range electron-electron interaction and quenched time-reversal\nsymmetric disorder (but excluding mass disorder). First we focus on the clean\ninteracting and the noninteracting dirty Dirac semimetal separately, and show\nthat they support two distinct quantum critical points. Using renormalization\ngroup techniques, we find that while interaction driven quantum critical points\nare \\emph{Gaussian} (mean-field) in nature, describing quantum phase\ntransitions into various broken symmetry phases, the ones controlled by\ndisorder are \\emph{non-Gaussian}, capturing the transition to a metallic phase.\nWe classify such diffusive quantum critical points based on the transformation\nof disorder vertices under a \\emph{continuous} chiral rotation. Our wek\ncoupling renormalization group analysis suggests that two distinct quantum\ncritical points are stable in an interacting dirty Dirac semimetal (with chiral\nsymmetric randomness), and a multicritical point (at finite interaction and\ndisorder) results from their interplay. By contrast, the chiral symmetry\nbreaking disorder driven critical point is unstable against weak interactions.\nEffects of weak disorder on the ordering tendencies in Dirac semimetal are\nanalyzed. The clean interacting critical points, however, satisfy the\n\\emph{Harris criterion}, and are therefore expected to be unstable against bond\ndisorder. Although our weak coupling analysis is inadequate to establish the\nultimate stability of these fixed points in the strong coupling regime (when\nboth interaction and disorder are strong), they can still govern crossover\nbehaviors in Dirac semimetals over a large length scale, when either\ninteraction or randomness is sufficiently weak.",
        "positive": "SiC Cantilevers For Generating Uniaxial Stress: This paper demonstrates the first beam resonators fabricated from bulk high\npurity semi-insulating 4H Silicon Carbide wafers (HPSI 4H-SiC). Our innovations\ninclude: (1) Multi-level front-side, back-side inductively coupled plasma-deep\nreactive ion etching (ICP-DRIE) technology to fabricate thin, low-mass,\nbending-mode resonators framed by the SiC substrate (2) Laser Doppler\nVibrometer (LDV) measurements of mechanical quality factors (Q) > 10,000 with\nfrequencies ranging from 300 kHz to 8MHz and (3) Calculated uniaxial in-plane\nsurface stress 20 MPa at top surface of resonator base when operating at\nresonance in vacuum."
    },
    {
        "anchor": "Carrier type modulation in current annealed graphene layers: We report on the electrical properties of current annealed graphene and few\nlayer graphene devices. It is observed that current annealing for several hours\nresults the n-type doping in the graphene layers. After current annealing Dirac\npoint start to shift toward positive gate voltage and saturate at some fixed\ngate voltage. N-type conduction in current annealed graphene layers is caused\nby the charge trapping in oxide layer during current annealing and recovery of\ncharge neutrality point with time span is understood due to the de-trapping of\ncharge with time.",
        "positive": "Active magneto-optical control of spontaneous emission in graphene: We investigate the spontaneous emission rate of a two-level quantum emitter\nnear a graphene-coated substrate under the influence of an external magnetic\nfield or strain induced pseudo-magnetic field. We demonstrate that the\napplication of the magnetic field can substantially increase or decrease the\ndecay rate. We show that a suppression as large as 99$\\%$ in the Purcell factor\nis achieved even for moderate magnetic fields. The emitter's lifetime is a\ndiscontinuous function of $|{\\bf B}|$, which is a direct consequence of the\noccurrence of discrete Landau levels in graphene. We demonstrate that, in the\nnear-field regime, the magnetic field enables an unprecedented control of the\ndecay pathways into which the photon/polariton can be emitted. Our findings\nstrongly suggest that a magnetic field could act as an efficient agent for\non-demand, active control of light-matter interactions in graphene at the\nquantum level."
    },
    {
        "anchor": "Landau-Zener transition between two quantum dots coupled by resonant\n  tunneling: We consider the transition of electron between two quantum dots in which the\ndiscrete levels are swept past each other with a constant velocity. If a direct\ntunneling between the dot levels was allowed, an electron will be transferred\nbetween the dots when the levels cross. This transfer is described in terms of\nthe conventional Landau-Zener theory. We assume that direct tunneling between\nthe dots is forbidden. Rather, the transfer is due to the resonant tunneling\nvia a discrete impurity level separating the dots. Then the description of the\nelectron transfer reduces to a threestate (two dots plus impurity) Landau-Zener\ntransition. Transition probability depends on the relative positions of the\nresonant level and the energy at which the levels cross. It also depends on the\nleft-right asymmetry of tunneling between the impurity and the left(right)\ndots. We calculate the transition probability in different limits of the\nhorizontal (in space) and vertical (in energy) impurity level positions.",
        "positive": "Theory of anyon excitons: Relation to excitons of nu=1/3 and nu=2/3\n  incompressible liquids: Elementary excitations of incompressible quantum liquids (IQL's) are anyons,\ni.e., quasiparticles carrying fractional charges and obeying fractional\nstatistics. To find out how the properties of these quasiparticles manifest\nthemselves in the optical spectra, we have developed the anyon exciton model\n(AEM) and compared the results with the finite-size data for excitons of nu=1/3\nand nu=2/3 IQL's. The model considers an exciton as a neutral composite\nconsisting of three quasielectrons and a single hole. The AEM works well when\nthe separation between electron and hole confinement planes, h, is larger than\nthe magnetic length l. In the framework of the AEM an exciton possesses\nmomentum k and two internal quantum numbers, one of which can be chosen as the\nangular momentum, L, of the k=0 state. Existence of the internal degrees of\nfreedom results in the multiple branch energy spectrum, crater-like electron\ndensity shape and 120 degrees density correlations for k=0 excitons, and the\nsplitting of the electron shell into bunches for non-zero k excitons. For h\nlarger than 2l the bottom states obey the superselection rule L=3m (m are\nintegers starting from 2), all of them are hard core states. For h nearly 2l\nthere is one-to-one correspondence between the low-energy spectra found for the\nAEM and the many- electron exciton spectra of the nu=2/3 IQL, whereas some\nstates are absent from the many-electron spectra of the nu=1/3 IQL. We argue\nthat this striking difference in the spectra originates from the different\npopulational statistics of the quasielectrons of charge conjugate IQL's and\nshow that the proper account of the statistical requirements eliminates\nexcessive states from the spectrum. Apparently, this phenomenon is the first\nmanifestation of the exclusion statistics in the anyon bound states."
    },
    {
        "anchor": "Temperature Control of Electromigration to form Gold Nanogap Junctions: Controlled electromigration of gold nanowires of different cross-sectional\nareas to form nanogap junctions is studied using a feedback method. A linear\ncorrelation between the cross sectional area of the gold nanowires and the\npower dissipated in the junction during electromigration is observed,\nindicating that the feedback mechanism operates primarily by controlling the\ntemperature of the junction during electromigration. We also show that the role\nof the external feedback circuit is to prevent thermal runaway; minimization of\nseries resistance allows controlled electromigration to a significant range of\njunction resistances with a simple voltage ramp.",
        "positive": "An experimental study on $\u0393$(2) modular symmetry in the quantum\n  Hall system with a small spin-splitting: Magnetic-field-induced phase transitions were studied with a two-dimensional\nelectron AlGaAs/GaAs system. The temperature-driven flow diagram shows the\nfeatures of the $\\Gamma$(2) modular symmetry, which includes distorted\nflowlines and shiftted critical point. The deviation of the critical\nconductivities is attributed to a small but resolved spin splitting, which\nreduces the symmetry in Landau quantization. [B. P. Dolan, Phys. Rev. B 62,\n10278.] Universal scaling is found under the reduction of the modular symmetry.\nIt is also shown that the Hall conductivity could still be governed by the\nscaling law when the semicircle law and the scaling on the longitudinal\nconductivity are invalid. *corresponding author:yhchang@phys.ntu.edu.tw"
    },
    {
        "anchor": "Frictional drag between superconducting LaAlO$_3$/SrTiO$_3$ nanowires: We report frictional drag measurements between two superconducting\nLaAlO$_3$/SrTiO$_3$ nanowires. In these experiments, current passing through\none nanowire induces a voltage across a nearby electrically isolated nanowire.\nThe frictional drag signal contains both symmetric and antisymmetric\ncomponents. The antisymmetric component arises from the rectification of\nquantum shot noise in the drive nanowire by the broken symmetry in the drag\nnanowire. The symmetric component in the drag resistance is ascribed to\nrectification of thermal noise in the drive nanowire during\nsuperconducting-normal transition. The suppression of the symmetric component\nis observed when a normal nanowire is used as either a drag or drive nanowire\nwith the other nanowire superconducting. The absence of symmetric drag\nresistance between a normal drag nanowire and a superconducting drive nanowire\nsuggests a higher electron-hole asymmetry in the superconducting\nLaAlO$_3$/SrTiO$_3$ nanowire arising from the 1D nature of superconductivity at\nLaAlO$_3$/SrTiO$_3$ interface.",
        "positive": "Multistability and spin diffusion enhanced lifetimes in dynamic nuclear\n  polarization in a double quantum dot: The control of nuclear spins in quantum dots is essential to explore their\nmany-body dynamics and exploit their prospects for quantum information\nprocessing. We present a unique combination of dynamic nuclear spin\npolarization and electric-dipole-induced spin resonance in an electrostatically\ndefined double quantum dot (DQD) exposed to the strongly inhomogeneous field of\ntwo on-chip nanomagnets. Our experiments provide direct and unrivaled access to\nthe nuclear spin polarization distribution and allow us to establish and\ncharacterize multiple fixed points. Further, we demonstrate polarization of the\nDQD environment by nuclear spin diffusion which significantly stabilizes the\nnuclear spins inside the DQD."
    },
    {
        "anchor": "Dynamic localization and Coulomb blockade in quantum dots under AC\n  pumping: We study conductance through a quantum dot under Coulomb blockade conditions\nin the presence of an external periodic perturbation. The stationary state is\ndetermined by the balance between the heating of the dot electrons by the\nperturbation and cooling by electron exchange with the cold contacts. We show\nthat Coulomb blockade peak can have a peculiar shape if heating is affected by\ndynamic localization, which can be an experimental signature of this effect.",
        "positive": "Photocurrent and photoconductance of an helical edge state: We consider the helical edge state of a Quantum Spin Hall insulator,\nconnected between two leads, and irradiated by a monochromatic and circularly\npolarized electromagnetic wave. The photocurrent generated within the helical\nedge state is studied as function of the characteristics of the electromagnetic\nradiation and electronic doping of the edge state. We focus on the effect of\nthe leads on the photocurrent. We also investigate the photoconductance of the\nhelical edge state in presence of a voltage bias between the leads."
    },
    {
        "anchor": "Dephasing-Induced Stabilization of a Perfectly Conducting Channel in\n  Disordered Graphene Nanoribbons with Zigzag Edges: Electron transport in a disordered graphene nanoribbon with zigzag edges is\ncrucially affected by a perfectly conducting channel (PCC), which is stabilized\nif intervalley scattering is ignorable. In the presence of such a PCC, the\ndimensionless conductance g of the system decreases to the quantized value of g\n= 1 with increasing system length L. In the realistic case where intervalley\nscattering is weak but not ignorable, the PCC is gradually destabilized with\nincreasing L, and g eventually decays to zero owing to the onset of Anderson\nlocalization. Here, we show that such destabilization of the PCC can be relaxed\nby pure dephasing. We numerically calculate g in the presence of long-range\nimpurities, which induce weak intervalley scattering, taking the dephasing\neffect into account. It is demonstrated that, under sufficient dephasing, the\ndecay of g in the regime of g \\lesssim 1 is strongly suppressed and the\nquasi-quantization of g (i.e., g ~ 1) can be observed in a wide region of L.",
        "positive": "Entanglement and decoherence of a micromechanical resonator via coupling\n  to a Cooper box: We analyse the quantum dynamics of a micromechanical resonator capacitively\ncoupled to a Cooper box. With appropriate quantum state control of the Cooper\nbox, the resonator can be driven into a superposition of spatially separated\nstates. The Cooper box can also be used to probe the environmentally-induced\ndecoherence of the resonator superposition state."
    },
    {
        "anchor": "Strain-engineering the Schottky barrier and electrical transport on MoS2: Strain provides an effective means to tune the electrical properties while\nretaining the native chemical composition of the material. Unlike\nthree-dimensional solids, two-dimensional materials withstand higher levels of\nelastic strain making it easier to tune various electrical properties to suit\nthe technology needs. In this work we explore the effect of uniaxial\ntensile-strain on the electrical transport properties of bi- and few-layered\nMoS2, a promising 2D semiconductor. Raman shifts corresponding to the in-plane\nvibrational modes show a redshift with strain indicating a softening of the\nin-plane phonon modes. Photo luminescence measurements reveal a redshift in the\ndirect and the indirect emission peaks signalling a reduction in the material\nbandgap. Transport measurements show a substantial enhancement in the\nelectrical conductivity with a high piezoresistive gauge factor of ~ 321\nsuperior to that for Silicon for our bi-layered device. The simulations\nconducted over the experimental findings reveal a substantial reduction of the\nSchottky barrier height at the electrical contacts in addition to the\nresistance of MoS2. Our studies reveal that strain is an important and\nversatile ingredient to tune the electrical properties of 2D materials and also\ncan be used to engineer high-efficiency electrical contacts for future device\nengineering.",
        "positive": "Which nanowire couples better electrically to a metal contact: armchair\n  or zigzag nanotube?: The fundamental question of how chirality affects the electronic coupling of\na nanotube to metal contacts is important for the application of nanotubes as\nnanowires. We show that metallic-zigzag nanotubes are superior to armchair\nnanotubes as nanowires, by modeling the metal-nanotube interface. More\nspecifically, we show that as a function of coupling strength, the total\nelectron transmission of armchair nanotubes increases and tends to be pinned\nclose to unity for a metal with Fermi wave vector close to that of gold. In\ncontrast, the total transmission of zigzag nanotubes increases to the maximum\npossible value of two. The origin of these effects lies in the details of the\nwave function, which is explained."
    },
    {
        "anchor": "Part of a collection of reviews on antiferromagnetic spintronics.\n  Antiferromagnetic dynamics, spin-texures, and nanostructures: Antiferromagnets as active elements of spintronics can be faster than their\nferromagnetic counterparts and more robust to magnetic noise. Owing to the\nstrongly exchange-coupled magnetic sublattice structure, antiferromagnetic\norder parameter dynamics are qualitatively different and thus capable of\nengendering novel device functionalities. In this review, we discuss\nantiferromagnetic textures -- nanoparticles, domain walls, and skyrmions, --\nunder the action of different spin torques. We contrast the antiferromagnetic\nand ferromagnetic dynamics, with a focus on the features that can be relevant\nfor applications.",
        "positive": "Phonon polaritonics in two-dimensional materials: Extreme confinement of electromagnetic energy by phonon polaritons holds the\npromise of strong and new forms of control over the dynamics of matter. To\nbring such control to the atomic-scale limit, it is important to consider\nphonon polaritons in two-dimensional (2D) systems. Recent studies have pointed\nout that in 2D, splitting between longitudinal and transverse optical (LO and\nTO) phonons is absent at the $\\Gamma$ point, even for polar materials. Does\nthis lack of LO--TO splitting imply the absence of a phonon polariton in polar\nmonolayers? Here, we derive a first-principles expression for the conductivity\nof a polar monolayer specified by the wavevector-dependent LO and TO phonon\ndispersions. In the long-wavelength (local) limit, we find a universal form for\nthe conductivity in terms of the LO phonon frequency at the $\\Gamma$ point, its\nlifetime, and the group velocity of the LO phonon. Our analysis reveals that\nthe phonon polariton of 2D is simply the LO phonon of the 2D system. For the\nspecific example of hexagonal boron nitride (hBN), we estimate the confinement\nand propagation losses of the LO phonons, finding that high confinement and\nreasonable propagation quality factors coincide in regions which may be\ndifficult to detect with current near-field optical microscopy techniques.\nFinally, we study the interaction of external emitters with two-dimensional hBN\nnanostructures, finding extreme enhancement of spontaneous emission due to\ncoupling with localized 2D phonon polaritons, and the possibility of multi-mode\nstrong and ultra-strong coupling between an external emitter and hBN phonons.\nThis may lead to the design of new hybrid states of electrons and phonons based\non strong coupling."
    },
    {
        "anchor": "Spin-dependent transport through magnetic nanojunctions: Coherent electronic transport through a molecular device is studied using\nnon-equilibrium Green's function (NEGF) formalism. Such device is made of a\ncarbon nanowire which is connected to ferromagnetic electrodes. The molecule\nitself is described with the help of Hubbard model (Coulomb interactions are\ntreated by means of the Hartree-Fock approximation), while the coupling to the\nelectrodes is modeled through the use of a broad-band theory. It was shown that\nmagnetoresistance varies periodically with increasing the length of atomic wire\n(in the linear response regime) and oscillates with increasing of bias voltage\n(in the nonlinear response regime). Since the TMR effect for analyzed\nstructures is predicted to be large (tens of percentage), considered junctions\nseem to be suitable for application as a magnetoresistive elements in the\nfuture electronic circuits.",
        "positive": "In-plane magnetic field dependence of cyclotron relaxation time in a Si\n  two-dimensional electron system: Cyclotron resonance of two-dimensional electrons is studied for a\nhigh-mobility Si/SiGe quantum well in the presence of an in-plane magnetic\nfield, which induces spin polarization. The relaxation time $\\tau_{CR}$ shows a\nnegative in-plane magnetic field dependence, which is similar to that of the\ntransport scattering time $\\tau_t$ obtained from dc resistivity. The resonance\nmagnetic field shows an unexpected negative shift with increasing in-plane\nmagnetic field."
    },
    {
        "anchor": "Photonic Floquet skin-topological effect: Non-Hermitian skin effect and photonic topological edge states are of great\ninterest in non-Hermitian physics and optics. However, the interplay between\nthem is largly unexplored. Here, we propose and demonstrate experimentally the\nnon-Hermitian skin effect that constructed from the nonreciprocal flow of\nFloquet topological edge states, which can be dubbed 'Floquet skin-topological\neffect'. We first show the non-Hermitian skin effect can be induced by pure\nloss when the one-dimensional (1D) system is periodically driven. Next, based\non a two-dimensional (2D) Floquet topological photonic lattice with structured\nloss, we investigate the interaction between the non-Hermiticity and the\ntopological edge states. We observe that all the one-way edge states are\nimposed onto specific corners, featuring both the non-Hermitian skin effect and\ntopological edge states. Furthermore, a topological switch for the\nskin-topological effect is presented by utilizing the gap-closing mechanism.\nOur experiment paves the way of realizing non-Hermitian topological effects in\nnonlinear and quantum regimes.",
        "positive": "Topological phases and surface flat bands in superconductors without\n  inversion symmetry: We examine different topological phases in three-dimensional\nnon-centrosymmetric superconductors with time-reversal symmetry by using three\ndifferent types of topological invariants. Due to the bulk boundary\ncorrespondence, a non-zero value of any of these topological numbers indicates\nthe appearance of zero-energy Andreev surface states. We find that some of\nthese boundary modes in nodal superconducting phases are dispersionless, i.e.,\nthey form a topologically protected flat band. The region where the zero-energy\nflat band appears in the surface Brillouin zone is determined by the projection\nof the nodal lines in the bulk onto the surface. These dispersionless Andreev\nsurface bound states have many observable consequences, in particular, a\nzero-bias conductance peak in tunneling measurements. We also find that in the\ngapless phase there appear Majorana surface modes at time-reversal invariant\nmomenta which are protected by a $\\mathbb{Z}_2$ topological invariant."
    },
    {
        "anchor": "Graphene in the Quantum Hall Regime: Effects of Vacancies, Sublattice\n  Polarization and Disorder: We investigate the effects of vacancies, disorder and sublattice polarization\non the electronic properties of a monolayer graphene in the quantum Hall\nregime. Energy spectra as a function of magnetic field and the localization\nproperties of the states within the graphene Landau levels (LLs) are calculated\nthrough a tight-binding model. We first discuss our results considering\nvacancies in the lattice, where we show that vacancies introduce extra levels\n(or well-defined bands) between consecutive LLs. An striking consequence here\nis that extra Hall resistance plateaus are expected to emerge when an organized\nvacancy superlattice is considered. Secondly, we discuss the anomalous\nlocalization properties we have found for the lowest LL, where an increasing\ndisorder is shown to enhance the wave functions delocalization (instead of\ninducing localization). This unexpected effect is shown to be directly related\nto the way disorder increasingly destroys the sublattice (valley) polarization\nof the states in the lowest LL. The reason why this anomalous disorder effect\noccurs only for the zero-energy LL is that, in absence of disorder, only for\nthis level all the states are sublattice polarized, i.e., their wave functions\nhave amplitudes in only one of the sublattices.",
        "positive": "Coulomb drag by small momentum transfer between quantum wires: We demonstrate that in a wide range of temperatures Coulomb drag between two\nweakly coupled quantum wires is dominated by processes with a small interwire\nmomentum transfer. Such processes, not accounted for in the conventional\nLuttinger liquid theory, cause drag only because the electron dispersion\nrelation is not linear. The corresponding contribution to the drag resistance\nscales with temperature as T^2 if the wires are identical, and as T^5 if the\nwires are different."
    },
    {
        "anchor": "Active Material, Optical Mode and Cavity Impact on electro-optic\n  Modulation Performance: In this paper, three different materials Si, ITO and graphene; and three\ndifferent types of mode structures bulk, slot and hybrid; based on their\nelectrooptical and electro absorptive aspects in performance are analyzed. The\nstudy focuses on three major characteristics of electrooptic tuning, i.e.\nmaterial, modal and cavity dependency. The materials are characterized with\nestablished models and the allowed ranges for their key parameter spectra are\nanalyzed with desired tuning in mind; categorizing into n and k dominant\nregions for plausible electrooptic and electro absorptive applications,\nrespectively. A semi analytic approach, with the aid of FEM simulations for the\neigenmode calculations, was used for this work. Electrooptic tuning i.e.\nresonance shift properties inside Fabry Perot cavities are investigated with\nmodal and scaling concerns in mind. Tuning changes the effective complex\nrefractive index of the mode dictated by the Kramers Kronig relations which\nsubsequently suggest a tradeoff between the resonance shift and increasing\nlosses. The electrical tuning properties of the different modes in the cavity\nare analyzed, and subsequently a figure of merit, delta-lambda/delta-alpha was\nchosen with respect to carrier concentration and cavity scaling to find\nprospective suitable regions for desired tuning effects.",
        "positive": "Circuit-Model Analysis for Spintronic Devices with Chiral Molecules as\n  Spin Injectors: Recent research discovered that charge transfer processes in chiral molecules\ncan be spin selective and named the effect chiral-induced spin selectivity\n(CISS). Follow-up work studied hybrid spintronic devices with conventional\nelectronic materials and chiral (bio)molecules. However, a theoretical\nfoundation for the CISS effect is still in development and the spintronic\nsignals were not evaluated quantitatively. We present a circuit-model approach\nthat can provide quantitative evaluations. Our analysis assumes the scheme of a\nrecent experiment that used photosystem~I (PSI) as spin injectors, for which we\nfind that the experimentally observed signals are, under any reasonable\nassumptions on relevant PSI time scales, too high to be fully due to the CISS\neffect. We also show that the CISS effect can in principle be detected using\nthe same type of solid-state device, and by replacing silver with graphene, the\nsignals due to spin generation can be enlarged four orders of magnitude. Our\napproach thus provides a generic framework for analyzing this type of\nexperiments and advancing the understanding of the CISS effect."
    },
    {
        "anchor": "New degeneracies and modification of Landau levels in the presence of a\n  parallel linear electric field: We consider a three-dimensional system where an electron moves under a\nconstant magnetic field (in the z-direction) and a \\textit{linear} electric\nfield parallel to the magnetic field above the z=0 plane and anti-parallel\nbelow the plane. The linear electric field leads to harmonic oscillations along\nthe z-direction. There are therefore two frequencies characterizing the system:\nthe usual cyclotron frequency $\\omega_c$ corresponding to motion along the x-y\nplane and associated with Landau levels and a second frequency $\\omega_z$ for\nmotion along the z-direction. Most importantly, when the ratio\n$W=\\omega_c/\\omega_z$ is a rational number, the degeneracy of the energy levels\ndoes not remain always constant as the energy increases. At some energies, the\ndegeneracy jumps i.e. it increases. In particular, when the two frequencies are\nequal, the degeneracy increases with each energy level. This is in stark\ncontrast to the usual Landau levels where the degeneracy is independent of the\nenergy. We derive compact analytical formulas for the degeneracy. We also\nobtain an analytical formula for the energy levels and plot them as a function\nof $W$. The increase in degeneracy can readily be seen in the plot at points\nwhere lines intersect. For concreteness, we consider the electric field\nproduced by a uniformly charged ring. Besides a linear electric field in the z\ndirection the ring produces an extra electric field in the xy plane which we\ntreat via perturbation theory. The Landau degeneracy is now lifted and replaced\nby tightly spaced levels that come in \"bands\". The plot of the energy levels\nshows that there is still a degeneracy where the bands intersect.",
        "positive": "Transport, Noise, and Conservation in the Electron Gas: How to Build a\n  Credible Mesoscopic Theory: The Boltzmann-Landau-Silin and Landauer-Buettiker-Imry theories of electron\ntransport are shown to be mutually incompatible. The first respects microscopic\ngauge invariance, electron-hole symmetry, and the conserving sum rules for the\ncorrelated electron gas. The second approach does not. That is directly evident\nin its unphysical compressibility."
    },
    {
        "anchor": "Molecular Graphene under the Eye of Scattering Theory: The recent experimental observations of designer Dirac Fermions and\ntopological phases in molecular graphene are addressed theoretically. Using\nscattering theory we calculate the electronic structure of finite lattices of\nscattering centers dual to the honeycomb lattice. In good agreement with\nexperimental observations, we obtain a V-shaped electron density of states\naround the Fermi energy. By varying the lattice parameter we simulate electron\nand hole doping of the structure and by adding and removing scattering centers\nwe simulate respectively vacancy and impurity defects. Specifically for the\nvacancy defect we verify the emergence of a sharp resonance near the Fermi\nenergy for increasing strength of the scattering potential.",
        "positive": "Negative polarizability of 2D electrons in HgTe quantum well: The polarizability of electrons occupying the lowest subband of spatial\nquantization in CdTe/Cd$_x$Hg$_{1-x}$Te/CdTe quantum wells is calculated. It is\nshown that polarizability in the quantum well without cadmium is negative,\ni.e., the displacement of an electron in an electric field applied\nperpendicularly to the quantum well plane is opposite to the force acting on\nit. The negative polarizability of 2D electrons can reduce the dielectric\nconstant of quantum wells by up to $(10-15)$ percent."
    },
    {
        "anchor": "Magnetic Actuation and Feedback Cooling of a Cavity Optomechanical\n  Torque Sensor: We demonstrate the integration of a mesoscopic ferromagnetic needle with a\ncavity optomechanical torsional resonator, and its use for quantitative\ndetermination of the needle's magnetic properties, as well as amplification and\ncooling of the resonator motion. With this system we measure torques as small\nas 32 zNm, corresponding to sensing an external magnetic field of 0.12 A/m (150\nnT). Furthermore, we are able to extract the magnetization (1710 kA/m) of the\nmagnetic sample, not known a priori, demonstrating this system's potential for\nstudies of nanomagnetism. Finally, we show that we can magnetically drive the\ntorsional resonator into regenerative oscillations, and dampen its mechanical\nmode temperature from room temperature to 11.6 K, without sacrificing torque\nsensitivity.",
        "positive": "Role of Spin Diffusion in Current-Induced Domain Wall Motion: Current-induced spin torque and magnetization dynamics in the presence of\nspin diffusion in magnetic textures is studied theoretically. We uncover an\nadditional torque on the form \\sim{\\bm\\nabla}^2[{\\bf M}x({\\bf u}\\cdot{\\bm\n\\nabla}){\\bf M}], where {\\bf M} is the local magnetization and {\\bf u} is the\ndirection of injected current. This torque is inversely proportional to the\nsquare of the domain wall width (\\approx\\frac{1}{W^2}) and strongly depends on\nthe domain wall structure. Whereas its influence remains moderate for\ntransverse domain walls, it can significantly increase the transverse velocity\nof vortex cores. Consequently, the spin diffusion can dramatically enhance the\nnon-adiabaticity of vortex walls."
    },
    {
        "anchor": "High-Temperature Majorana Corner States: Majorana bound states often occur at the end of 1D topological superconductor\nor at the $\\pi$ Josephson junction mediated by a helical edge state. Validated\nby a new bulk invariant and an intuitive edge argument, we show the emergence\nof one Majorana Kramers pair at each corner of a square-shaped 2D topological\ninsulator proximitized by an $s_\\pm$-wave (e.g., Fe-based) superconductor. We\nobtain a phase diagram that emphasizes the roles of bulk parameters and edge\norientations. We propose several experimental realizations in lattice-matched\ncandidate materials. Our scheme offers a high-temperature platform for\nexploring higher-order non-Abelian quasiparticles.",
        "positive": "Chiral switching and dynamic barrier reductions in artificial square ice: Collective dynamics in lithographically-defined artificial spin ices offer\nprofound insights into emergent correlations and phase transitions of\ngeometrically-frustrated Ising spin systems. Their temporal and spatial\nevolution are often simulated using kinetic Monte Carlo simulations, which rely\non the precise knowledge of the switching barriers to obtain predictive results\nin agreement with experimental observations. In many cases, however, the\nbarriers are derived from simplified assumptions only, and do not take into\naccount the full physical picture of nanomagnetic switching. Here we describe\nhow the immediate magnetic environment of a nanomagnet reversing via\nquasi-coherent rotation can induce clockwise and counter-clockwise switching\nchannels with different barrier energies. This barrier splitting for chiral\nreversal channels can be sizeable and, as string-method micromagnetic\nsimulations show, is relevant for artificial spin ice systems made of both\nexchange -- as well as magnetostatically --dominated units. Due to the barrier\nsplitting (and further reductions due to non-uniform reversal) transition rates\ncan be exponentially enhanced by several orders of magnitude compared to\nmean-field predictions, especially in the limit of rare switching events where\nthermal excitation is less likely. This leads to significantly faster\nrelaxation time scales and modified spatial correlations. Our findings are thus\nof integral importance to achieve realistic kinetic Monte Carlo simulations of\nemergent correlations in artificial spin systems, magnonic crystals, or the\nevolution of nanomagnetic logic circuits."
    },
    {
        "anchor": "Chiral skyrmion states in non-centrosymmetric magnets: Chiral skyrmion states exist in non - centrosymmetric magnetic crystals as a\nconsequence of the asymmetric exchange Dzyaloshinskii-Moriya interactions that\ndestroy the homogeneous magnetic state and generally lead to twisted\nincommensurate magnetic spin-structures. Recently, skyrmion lattices and free\nskyrmions in magnetic layers of the chiral helimagnets with the\nnoncentrosymmetric cubic B20 crystal structure have been observed. The\nstabilization of these states and their transformation properties impressively\nillustrate the theoretically predicted solitonic nature of these chiral\ntwo-dimensionally localized spin-states. This paper is mainly devoted to\nnumerically rigorous solutions of hexagonal skyrmion lattices for cubic\nhelimagnets. It justifies and extends previous approximate solutions that used\na circular cell approximation (CCA) for the calculation of the free energy of\nskyrmion lattices. The theoretical results of the present paper provide a\ncomprehensive description of skyrmion lattice evolution in an applied magnetic\nfield and/or in the presence of uniaxial, cubic, and exchange anisotropy. The\nlow-temperature phenomenological theory with fixed modulus of magnetization,\nM=const, is applied to the magnetic states in chiral magnets.",
        "positive": "Transmission Lines and Meta-Materials based on Quantum Hall Plasmonics: The characteristic impedance of a microwave transmission line is typically\nconstrained to a value $Z_0$ = 50 $ \\Omega$, in-part because of the low\nimpedance of free space and the limited range of permittivity and permeability\nrealizable with conventional materials. Here we suggest the possibility of\nconstructing high-impedance transmission lines by exploiting the plasmonic\nresponse of edge states associated with the quantum Hall effect in gated\ndevices. We analyze various implementations of quantum Hall transmission lines\nbased on distributed networks and lumped-element circuits, including a detailed\naccount of parasitic capacitance and Coulomb drag effects, which can modify\ndevice performance. We additionally conceive of a meta-material structure\ncomprising arrays of quantum Hall droplets and analyze its unusual properties.\nThe realization of such structures holds promise for efficiently wiring-up\nquantum circuits on chip, as well as engineering strong coupling between\nsemiconductor qubits and microwave photons."
    },
    {
        "anchor": "On-chip Maxwell's demon as an information-powered refrigerator: We present an experimental realization of an autonomous Maxwell's Demon,\nwhich extracts microscopic information from a System and reduces its entropy by\napplying feedback. It is based on two capacitively coupled single electron\ndevices, both integrated on the same electronic circuit. This setup allows a\ndetailed analysis of the thermodynamics of both the Demon and the System as\nwell as their mutual information exchange. The operation of the Demon is\ndirectly observed as a temperature drop in the System. We also observe a\nsimultaneous temperature rise in the Demon arising from the thermodynamic cost\nof generating the mutual information.",
        "positive": "Robust procedure for creating and characterizing the atomic structure of\n  scanning tunneling microscope tips: Scanning tunneling microscopes (STM) are used extensively for studying and\nmanipulating matter at the atomic scale. In spite of the critical role of the\nSTM tip, the control of the atomic-scale shape of STM tips remains a poorly\nsolved problem. Here, we present a method for preparing tips {\\it in-situ} and\nfor ensuring the crystalline structure and reproducibly preparing tip structure\nup to the second atomic layer. We demonstrate a controlled evolution of such\ntips starting from undefined tip shapes."
    },
    {
        "anchor": "Josephson current in strongly correlated double quantum dots: We study the transport properties of a serial double quantum dot (DQD)\ncoupled to two superconducting leads, focusing on the Josephson current through\nthe DQD and the associated 0-$\\pi$ transitions which result from the subtle\ninterplay between the superconductivity, the Kondo physics, and the inter-dot\nsuperexchange interaction. We examine the competition between the\nsuperconductivity and the Kondo physics by tuning the relative strength\n$\\Delta/T_K$ of the superconducting gap $\\Delta$ and the Kondo temperature\n$T_K$, for different strengths of the superexchange coupling determined by the\ninterdot tunneling $t$ relative to the dot level broadening $\\Gamma$. We find\nstrong renormalization of $t$, a significant role of the superexchange coupling\n$J$, and a rich phase diagram of the 0 and $\\pi$-junction regimes. In\nparticular, when both the superconductivity and the exchange interaction are in\nclose competion with the Kondo physics ($\\Delta\\sim J\\sim T_K$), there appears\nan island of $\\pi'$-phase at large values of the superconducting phase\ndifference.",
        "positive": "QCL active region overheat in pulsed mode: effects of non-equilibrium\n  heat dissipation on laser performance: Quantum cascade lasers are of high interest in the scientific community due\nto unique applications utilizing the emission in mid-IR range. The possible\ndesigns of QCL are quite limited and require careful engineering to overcome\nsome crucial disadvantages. One of them is an active region (ARn) overheat,\nthat significantly affects the laser characteristics in the pulsed operation\nmode. In this work we consider the effects related to the non-equilibrium\ntemperature distribution, when thermal resistance formalism is irrelevant. We\nemploy the heat equation and discuss the possible limitations and structural\nfeatures stemming from the chemical composition of the AR. We show that the\npresence of alloys in the ARn structure fundamentally limits the heat\ndissipation in pulsed and CW regimes due to their low thermal conductivity.\nAlso the QCL post-growths affects the thermal properties of a device only in\n(near)CW mode while it is absolutely invaluable in the pulsed mode"
    },
    {
        "anchor": "Spin-wave propagation in a microstructured magnonic crystal: Transmission of microwave spin waves through a microstructured magnonic\ncrystal in the form of a permalloy waveguide of a periodically varying width\nwas studied experimentally and theoretically. The spin wave characteristics\nwere measured by spatially-resolved Brillouin light scattering microscopy. A\nrejection frequency band was clearly observed. The band gap frequency was\ncontrolled by the applied magnetic field. The measured spin-wave intensity as a\nfunction of frequency and propagation distance is in good agreement with a\nmodel calculation.",
        "positive": "Coherent-Incoherent Crossover of Charge and Neutral Mode Transport as\n  Evidence for the Disorder-Dominated Fractional Edge Phase: Couplings between topological edge channels open electronic phases possessing\nnontrivial eigenmodes far beyond the noninteracting-edge picture. However,\ninelastic scatterings mask the eigenmodes' inherent features, often preventing\nus from identifying the phases, as is the case for the quintessential\nLandau-level filling factor v = 2/3 edge composed of the counter-propagating v\n= 1/3 and 1 (1/3-1) channels. Here, we study the coherent-incoherent crossover\nof the 1/3-1 channels by tuning the channel length in-situ using a new device\narchitecture comprising a junction of v = 1/3 and 1 systems, the particle-hole\nconjugate of the 2/3 edge. We successfully observed the concurrence of the\nfluctuating electrical conductance and the quantized thermal conductance in the\ncrossover regime, the definitive hallmark of the eigenmodes in the\ndisorder-dominated edge phase left experimentally unverified."
    },
    {
        "anchor": "Distributions of Conductance and Shot Noise and Associated Phase\n  Transitions: For a chaotic cavity with two indentical leads each supporting N channels, we\ncompute analytically, for large N, the full distribution of the conductance and\nthe shot noise power and show that in both cases there is a central Gaussian\nregion flanked on both sides by non-Gaussian tails. The distribution is weakly\nsingular at the junction of Gaussian and non-Gaussian regimes, a direct\nconsequence of two phase transitions in an associated Coulomb gas problem.",
        "positive": "Tuning of one-dimensional plasmons by Ag-Doping in Ag-$\\sqrt{3}$-ordered\n  atomic wires: We generated arrays of silver wires with a height of one atom and an average\nwidth of 11 atoms on the Si(557) surface via self assembly with local\n$\\sqrt{3}\\times\\sqrt{3}$ order, and investigated the 1D plasmon formation in\nthem using a combination of high resolution electron loss spectroscopy with low\nenergy electron diffraction. As it turned out by a series of thermal desorption\nexperiments followed by adding small concentrations of Ag, pure Ag-$\\sqrt{3}$\nordered arrays of nanowires, separated by (113) facets, are intrinsically\nsemi-metallic or semiconducting. Added Ag atoms in the range up to few percent\nof a monolayer result in 1D plasmon formation without any concentration\nthreshold. The quantitative Ag concentration dependence of the plasmonic losses\nis clearly non-linear and fully compatible with a $\\sqrt{n_e}$ dependence of\nthe 1D plasmon. Adsorption of traces of residual gas can have a qualitatively\nsimilar doping effect."
    },
    {
        "anchor": "Symmetry-protected Nodal Points and Nodal Lines in Magnetic Materials: Nodal-point and Nodal-line structures in the dispersion of electron energy\nbands are characterized by their high degeneracy in certain corners or lines in\nthe Brillouin zone (BZ). These nodal structures can also exist in the\ndispersion of itinerant electrons in magnetically ordered materials whose\nsymmetry groups are anti-unitary groups called the magnetic space groups. In\nthe present work, we provide a complete list of magnetic space groups which can\nhost symmetry-protected nodal-point/line band structures for spin-1/2 fermionic\nparticles, where the degeneracies at the nodal points/lines are guaranteed by\nirreducible projective representations (IPReps) of the little co-groups. Our\ndiscussion is restricted to the magnetic space groups whose magnetic point\ngroup contains the space-time inversion operation $\\tilde T=\\mathcal IT$, the\ncombined operation of spacial inversion $\\mathcal I$ and time reversal $T$,\nsuch that the energy bands are at least doubly-degenerate at arbitrary points\nin the BZ. For these magnetic point groups we provide the invariants to label\nthe classes of projective Reps, and for each class we calculate all the\ninequivalent IPReps. From the results we select out all the groups and the\ncorresponding Rep classes which support high-dimensional ($d\\geq$4) IPReps. We\nthen list the magnetic space groups and their high symmetry points/lines whose\nlittle co-groups have high-dimensional ($d\\geq$4) IPReps with the corresponding\nfactor systems. Examples of candidate materials are discussed.",
        "positive": "Design principles for long-range energy transfer at room temperature: Under physiological conditions, ballistic long-range transfer of electronic\nexcitations in molecular aggregates is generally expected to be suppressed by\nnoise and dissipative processes. Hence, quantum phenomena are not considered to\nbe relevant for the design of efficient and controllable energy transfer over\nsignificant length and time scales. Contrary to this conventional wisdom, here\nwe show that the robust quantum properties of small configurations of repeating\nclusters of molecules can be used to tune energy transfer mechanism that take\nplace on much larger scales. With the support of an exactly solvable model, we\ndemonstrate that coherent exciton delocalization and dark states within unit\ncells can be used to harness dissipative phenomena of varying nature\n(thermalization, fluorescence, non-radiative decay and weak inter-site\ncorrelations) to support classical propagation over macroscopic distances. In\nparticular, we argue that coherent delocalization of electronic excitations\nover just a few pigments can drastically alter the relevant dissipation\npathways which influence the energy transfer mechanism, and thus serve as a\nmolecular control tool for large-scale properties of molecular materials.\nBuilding on these principles, we use extensive numerical simulations to\ndemonstrate that they can explain currently not understood measurements of\nmicron-scale exciton diffusion in nano-fabricated arrays of bacterial\nphotosynthetic complexes. Based on these results we provide quantum design\nguidelines at the molecular scale to optimize both energy transfer speed and\nrange over macroscopic distances in artificial light-harvesting architectures."
    },
    {
        "anchor": "The Kondo effect in quantum dots at high voltage: Universality and\n  scaling: We examine the properties of a dc-biased quantum dot in the Coulomb blockade\nregime. For voltages V large compared to the Kondo temperature T_K, the physics\nis governed by the scales V and gamma, where gamma ~ V/ln^2(V/T_K) is the\nnon-equilibrium decoherence rate induced by the voltage-driven current. Based\non scaling arguments, self-consistent perturbation theory and perturbative\nrenormalization group, we argue that due to the large gamma, the system can be\ndescribed by renormalized perturbation theory for ln(V/T_K) >> 1. However, in\ncertain variants of the Kondo problem, two-channel Kondo physics is induced by\na large voltage V.",
        "positive": "Optically induced transport properties of freely suspended semiconductor\n  submicron channels: We report on optically induced transport phenomena in freely suspended\nchannels containing a two-dimensional electron gas (2DEG). The submicron\ndevices are fabricated in AlGaAs/GaAs heterostructures by etching techniques.\nThe photoresponse of the devices can be understood in terms of the combination\nof photogating and a photodoping effect. The hereby enhanced electronic\nconductance exhibits a time constant in the range of one to ten milliseconds."
    },
    {
        "anchor": "Multilayer Haldane model: We propose the model of layered materials, in which each layer is described\nby the conventional Haldane model, while the inter - layer hopping parameter\ncorresponds to the ABC stacking. We calculate the topological invariant $N_3$\nfor the resulting model, which is responsible for the conductivity of intrinsic\nquantum Hall effect. It has been shown that in a certain range of the values of\ninterlayer hopping parameter, the value of $N_3$ is equal to the number of\nlayers multiplied by the topological invariant of each layer. At the same time\nthis value may be calculated using the low energy effective theory.",
        "positive": "Valley Manipulation by Optically Tuning the Magnetic Proximity Effect in\n  WSe$_2$/CrI$_3$ Heterostructures: Monolayer valley semiconductors, such as tungsten diselenide (WSe$_2$),\npossess valley pseudospin degrees of freedom that are optically addressable but\ndegenerate in energy. Lifting the energy degeneracy by breaking time-reversal\nsymmetry is vital for valley manipulation. This has been realized by directly\napplying magnetic fields or via pseudo-magnetic fields generated by intense\ncircularly polarized optical pulses. However, sweeping large magnetic fields is\nimpractical for devices, and the pseudo-magnetic fields are only effective in\nthe presence of ultrafast laser pulses. The recent rise of two-dimensional (2D)\nmagnets unlocks new approaches to control valley physics via van der Waals\nheterostructure engineering. Here we demonstrate wide continuous tuning of the\nvalley polarization and valley Zeeman splitting with small changes in the laser\nexcitation power in heterostructures formed by monolayer WSe$_2$ and 2D\nmagnetic chromium triiodide (CrI$_3$). The valley manipulation is realized via\noptical control of the CrI$_3$magnetization, which tunes the magnetic exchange\nfield over a range of 20 T. Our results reveal a convenient new path towards\noptical control of valley pseudospins and van der Waals magnetic\nheterostructures."
    },
    {
        "anchor": "Determining Strain Components in a Diamond Waveguide from Zero-Field\n  ODMR Spectra of NV$^{-}$ Center Ensembles: The negatively charged nitrogen-vacancy (NV${}^-$) center in diamond has\nshown great potential in nanoscale sensing and quantum information processing\ndue to its rich spin physics. An efficient coupling with light, providing\nstrong luminescence, is crucial for realizing these applications. Laser-written\nwaveguides in diamond promote NV${}^-$ creation and improve their coupling to\nlight but at the same time induce strain in the crystal. The induced strain\ncontributes to light guiding but also affects the energy levels of NV${}^-$\ncenters. We probe NV${}^-$ spin states experimentally with the commonly used\nzero-field optically detected magnetic resonance (ODMR). In our waveguides, the\nODMR spectra are shifted, split, and consistently asymmetric, which we\nattribute to the impact of local strain. To understand these features, we model\nensemble ODMR signals in the presence of strain. By fitting the model results\nto the experimentally collected ODMR data we determine the strain tensor\ncomponents at different positions, thus determining the strain profile across\nthe waveguide. We show that ODMR spectroscopy can be used as a strain imaging\ntool. The resulting strain within the waveguide is dominated by a compressive\naxial component transverse to the waveguide structure, with a smaller\ncontribution from vertical and shear strain components.",
        "positive": "Low-field quantum Hall transport in an electron Fabry-Perot\n  interferometer: Determination of constriction filling vs front-gate voltage: We report systematic quantum Hall transport experiments on Fabry-Perot\nelectron interferometers at ultra-low-temperatures. The GaAs/AlGaAs\nheterostructure devices consist of two constrictions defined by etch trenches\nin 2D electron layer, enclosing an approximately circular island. Front gates\ndeposited in etch trenches allow to fine-tune the device for symmetry and to\nchange the constriction filling, relative to the bulk. The low-field\nlongitudinal and Hall magnetotransport shows Shubnikov-de Haas oscillations and\ninteger quantum Hall plateaus. A systematic variation of front-gate voltage\naffects the constriction and the island electron density, while the bulk\ndensity remains unaffected. This results in quantized plateaus in longitudinal\nresistance, while the Hall resistance is dominated by the low-density,\nlow-filling constriction. At lower fields, when the quantum Hall plateaus fail\nto develop, we observe bulk Shubnikov-de Haas oscillations in series\ncorresponding to an integer filling of the magnetoelectric subbands in the\nconstrictions. This indicates that the whole interferometer region is still\nquantum-coherent at these lower fields at 10 mK. Analyzing the data within a\nFock-Darwin model, we obtain the constriction electron density as a function of\nthe front gate bias and, extrapolating to the zero field, the number of\nelectric subbands (conductance channels) resulting from the electron\nconfinement in the constrictions."
    },
    {
        "anchor": "Counter-propagating Fractional Hall states in mirror-symmetric Dirac\n  semi-metals: The Landau bands of mirror symmetric 2D Dirac semi-metals (for example\nodd-layers of ABA-graphene) can be identified by their parity with respect to\nmirror symmetry. This symmetry facilitates a new class of counter-propagating\nHall states at opposite but equal electron and hole filling factors\n$|\\nu_{\\pm}|=1/m$ ({\\it m} odd). Here, we propose a Laughlin-like correlated\nliquid wavefunction, at the charge neutrality point, that exhibits fractionally\ncharged quasi-particle/hole pair excitation of opposite parity. Using a\nbosonized one-dimensional edge state theory, we show that the longitudinal\nconductance of this state, $\\sigma_{xx} = 2e^2/(m h)$, is robust to\nshort-ranged inter-mode interactions.",
        "positive": "Experimental demonstration of position-controllable topological\n  interface states in high-frequency topological integrated circuits: Topological integrated circuits are integrated-circuit realizations of\ntopological systems. Here we show an experimental demonstration by taking the\ncase of the Kitaev topological superconductor model. An integrated-circuit\nimplementation enables us to realize high resonant frequency as high as 13GHz.\nWe explicitly observe the spatial profile of a topological edge state. In\nparticular, the topological interface state between a topological segment and a\ntrivial segment is the Majorana-like state. We construct a switchable structure\nin the integrated circuit, which enables us to control the position of a\nMajorana-like interface state arbitrarily along a chain. Our results contribute\nto the development of topological electronics with high frequency integrated\ncircuits."
    },
    {
        "anchor": "Unveiling the optical emission channels of monolayer semiconductors\n  coupled to silicon nanoantennas: Monolayers (MLs) of transition metal dichalcogenides (TMDs) such as WSe2 and\nMoSe2 can be placed by dry stamping directly on broadband dielectric\nresonators, which have the ability to enhance the spontaneous emission rate and\nbrightness of solid-state emitters at room temperature. We show strongly\nenhanced emission and directivity modifications in room temperature\nphotoluminescence mapping experiments. By varying TMD material (WSe2 versus\nMoSe2) transferred on silicon nanoresonators with various designs (planarized\nversus non-planarized), we experimentally separate the different physical\nmechanisms that govern the global light emission enhancement. For WSe2 and\nMoSe2 we address the effects of Mie Resonances and strain in the monolayer. For\nWSe2 an important additional contribution comes from out-of-plane exciton\ndipoles. This paves the way for more targeted designs of TMD-Si nanoresonator\nstructures for room temperature applications.",
        "positive": "Energy levels of graphene magnetic quantum dot in inhomogeneous gap: We investigate the energy levels of charge carriers confined in a magnetic\nquantum dot in graphene with an inhomogeneous gap through an electrical\npotential. We solve the eigenvalue equation for two regions. We explicitly\ndetermine the eigenspinors for both valleys $ K $, $ K' $ and use the boundary\ncondition at the quantum dot interface to obtain the energy levels. We show\nthat the energy levels exhibit symmetric and asymmetric behavior under\nappropriate conditions of the physical parameters. It has been found that\nchanging the energy levels by introducing an energy gap outside the quantum dot\nchanges the electrical properties."
    },
    {
        "anchor": "General Geometric Fluctuation Modeling for Device Variability Analysis: The authors propose a new modeling approach based on the impedance field\nmethod (IFM) to analyze the general geometric variations in device simulations.\nCompared with the direct modeling of multiple variational devices, the proposed\ngeometric variation (GV) model shows a better efficiency thanks to its IFM\nbased nature. Compared with the existing random geometric fluctuation (RGF)\nmodel where the noise sources are limited to the interfaces, the present GV\nmodel provides better accuracy and wider application areas as it transforms the\ngeometric variation into global mesh deformation and computes the noise sources\ninduced by the geometric variation in the whole simulation domain. GV model\nalso provides great insights into the device by providing the effective noise\nsources, equation-wise contributions, and sensitivity maps that are useful for\ndevice characterization and optimization.",
        "positive": "Tunable Hybridization Between Electronic States of Graphene and\n  Physisorbed Hexacene: Non-covalent functionalization via physisorption of organic molecules\nprovides a scalable approach for modifying the electronic structure of graphene\nwhile preserving its excellent carrier mobilities. Here we investigated the\nphysisorption of long-chain acenes, namely, hexacene and its fluorinated\nderivative perfluorohexacene, on bilayer graphene for tunable graphene devices\nusing first principles methods. We find that the adsorption of these molecules\nleads to the formation of localized states in the electronic structure of\ngraphene close to its Fermi level, which could be readily tuned by an external\nelectric field. The electric field not only creates a variable band gap as\nlarge as 250 meV in bilayer graphene, but also strongly influences the charge\nredistribution within the molecule-graphene system. This charge redistribution\nis found to be weak enough not to induce strong surface doping, but strong\nenough to help preserve the electronic states near the Dirac point of graphene."
    },
    {
        "anchor": "Electric control of topological phase transitions in Dirac semimetal\n  thin films: We investigate the effect of a vertical electric field on a Dirac semimetal\nthin film. We show that through the interplay between the quantum confinement\neffect and the field-induced coupling between sub-bands, the sub-band gap can\nbe tuned and inverted, during which the system undergoes a topological phase\ntransition between a trivial band insulator and a quantum spin Hall insulator.\nConsequently, one can electrically switch the topological edge channels on and\noff, making the system a promising platform for constructing a topological\nfield effect transistor.",
        "positive": "Moire synaptic transistor for homogeneous-architecture reservoir\n  computing: Reservoir computing has been considered as a promising intelligent computing\nparadigm for effectively processing complex temporal information. Exploiting\ntunable and reproducible dynamics in the single electronic device have been\ndesired to implement the reservoir and the readout layer of reservoir computing\nsystem. Two-dimensional moire material, with an artificial lattice constant\nmany times larger than the atomic length scale, is one type of most studied\nartificial quantum materials in community of material science and\ncondensed-matter physics over the past years. These materials are featured with\ngate-tunable periodic potential and electronic correlation, thus varying the\nelectric field allows the electrons in the moire potential per unit cell to\nexhibit distinct and reproducible dynamics, showing great promise in robust\nreservoir computing. Here, we report that a moire synaptic transistor can be\nused to implement the reservoir computing system with a homogeneous\nreservoir-readout architecture. The synaptic transistor is fabricated based on\na h-BN/bilayer graphene/h-BN moire heterostructure, exhibiting\nferroelectricity-like hysteretic gate voltage dependence of resistance. Varying\nthe magnitude of the gate voltage enables the moire transistor to be switched\nbetween long-term memory and short-term memory with nonlinear dynamics. By\nemploying the short- and long-term memory as the reservoir nodes and weights of\nthe readout layer, respectively, we construct a full-moire physical neural\nnetwork and demonstrate that the classification accuracy of 90.8% can be\nachieved for the MNIST handwritten digit database. Our work would pave the way\ntowards the development of neuromorphic computing based on the moire materials."
    },
    {
        "anchor": "Surface magnon spectra of nodal loop semimetals: In this paper we establish a connection between the bulk topological\nstructure and the magnetic properties of drumhead surface states of nodal loop\nsemimetals. We identify the magnetic characteristics of the surface states and\ncompute the system's magnon spectrum by treating electron-electron interactions\non a mean-field level. We draw attention to a subtle connection between a\nLifshitz-like transition of the surface states driven by mechanical distortions\nand the magnetic characteristics of the system. Our findings may be\nexperimentally verified e.g. by spin polarized electron energy loss\nspectroscopy of nodal semimetal surfaces.",
        "positive": "Zero modes in magnetic systems: general theory and an efficient\n  computational scheme: The presence of topological defects in magnetic media often leads to normal\nmodes with zero frequency (zero modes). Such modes are crucial for long-time\nbehavior, describing, for example, the motion of a domain wall as a whole.\nConventional numerical methods to calculate the spin-wave spectrum in magnetic\nmedia are either inefficient or they fail for systems with zero modes. We\npresent a new efficient computational scheme that reduces the magnetic\nnormal-mode problem to a generalized Hermitian eigenvalue problem also in the\npresence of zero modes. We apply our scheme to several examples, including\ntwo-dimensional domain walls and Skyrmions, and show how the effective masses\nthat determine the dynamics can be calculated directly. These systems highlight\nthe fundamental distinction between the two types of zero modes that can occur\nin spin systems, which we call special and inertial zero modes. Our method is\nsuitable for both conservative and dissipative systems. For the latter case, we\npresent a perturbative scheme to take into account damping, which can also be\nused to calculate dynamical susceptibilities."
    },
    {
        "anchor": "Enhanced ponderomotive force in graphene due to interband resonance: We analyze intrinsic nonlinearities in two-dimensional polaritonic materials\ninteracting with an optical wave. Focusing on the case of graphene, we show\nthat the second-order nonlinear optical conductivity due to carrier density\nfluctuations associated with the excitation of a plasmon polariton is closely\nrelated to the ponderomotive force due to the oscillating optical field. This\nrelation is first established through an elegant thermodynamic approach for a\nDrude-like plasma, in the frequency range where intraband scattering is the\ndominant contribution to conductivity. Subsequently, we extend our analysis to\nthe interband regime, and show that for energies approximately half the Fermi\nenergy, the intraband contribution to the ponderomotive force diverges. In\npractice, thermal broadening regularizes this divergence as one would expect,\nbut even at room temperature typically leaves a strong ponderomotive\nenhancement. Finally, we study the impact of nonlocal corrections and find that\nnonlocality does not lead to further broadening (as one would expect in the\ncase of Landau damping), but rather to a splitting of the ponderomotive\ninterband resonance. Our analysis should prove useful to the open quest for\nexploiting nonlinearities in graphene and other two-dimensional polaritonic\nmaterials, through effects such as second harmonic generation and photon drag.",
        "positive": "A model study of present-day Hall-effect circulators: Stimulated by the recent implementation of a three-port Hall-effect microwave\ncirculator of Mahoney et al. (MEA), we present model studies of the performance\nof this device. Our calculations are based on the capacitive-coupling model of\nViola and DiVincenzo (VD). Based on conductance data from a typical Hall-bar\ndevice obtained from a two-dimensional electron gas (2DEG) in a magnetic field,\nwe numerically solve the coupled field-circuit equations to calculate the\nexpected performance of the circulator, as determined by the $S$ parameters of\nthe device when coupled to 50$\\Omega$ ports, as a function of frequency and\nmagnetic field. Above magnetic fields of 1.5T, for which a typical 2DEG enters\nthe quantum Hall regime (corresponding to a Landau-level filling fraction $\\nu$\nof 20), the Hall angle $\\theta_H=\\tan^{-1}\\sigma_{xy}/\\sigma_{xx}$ always\nremains close to $90^\\circ$, and the $S$ parameters are close to the analytic\npredictions of VD for $\\theta_H=\\pi/2$. As anticipated by VD, MEA find the\ndevice to have rather high (k$\\Omega$) impedance, and thus to be extremely\nmismatched to $50\\Omega$, requiring the use of impedance matching. We\nincorporate the lumped matching circuits of MEA in our modeling and confirm\nthat they can produce excellent circulation, although confined to a very small\nbandwidth. We predict that this bandwidth is significantly improved by working\nat lower magnetic field when the Landau index is high, e.g. $\\nu=20$, and the\nimpedance mismatch is correspondingly less extreme. Our modeling also confirms\nthe observation of MEA that parasitic port-to-port capacitance can produce very\ninteresting countercirculation effects."
    },
    {
        "anchor": "The missing atom as a source of carbon magnetism: Atomic vacancies have a strong impact in the mechanical, electronic and\nmagnetic properties of graphene-like materials. By artificially generating\nisolated vacancies on a graphite surface and measuring their local density of\nstates on the atomic scale, we have shown how single vacancies modify the\nelectronic properties of this graphene-like system. Our scanning tunneling\nmicroscopy experiments, complemented by tight binding calculations, reveal the\npresence of a sharp electronic resonance at the Fermi energy around each single\ngraphite vacancy, which can be associated with the formation of local magnetic\nmoments and implies a dramatic reduction of the charge carriers' mobility.\nWhile vacancies in single layer graphene naturally lead to magnetic couplings\nof arbitrary sign, our results show the possibility of inducing a macroscopic\nferrimagnetic state in multilayered graphene samples just by randomly removing\nsingle C atoms.",
        "positive": "Excitation and coherent control of magnetization dynamics in magnetic\n  tunnel junctions using acoustic pulses: We experimentally study magnetization dynamics in magnetic tunnel junctions\ndriven by femtosecond-laser-induced surface acoustic waves. The acoustic pulses\ninduce a magnetization precession in the free layer of the magnetic tunnel\njunction through magnetoelastic coupling. The frequency and amplitude of the\nprecession shows a pronounced dependence on the applied magnetic field and the\nlaser excitation position. Comparing the acoustic-wave-induced precession\nfrequencies with precession induced by charge currents and with micromagnetic\nsimulations we identify spatially non-uniform magnetization modes localized\nclose the edge regions as being responsible for the optically induced\nmagnetization dynamics. The experimental scheme even allows us to coherently\ncontrol the magnetization precession using two acoustic pulses. This might\nprove important for future applications requiring ultrafast spin manipulation.\nAdditionally, our results directly pinpoint the importance of acoustic pulses\nsince they could be relevant when investigating optically-induced temperature\neffects in magnetic structures."
    },
    {
        "anchor": "Optical conductivity in graphene: hydrodynamic regime: Experimental investigation of hydrodynamics in electron fluids is a highly\ntopical research area that emerged during the last few years. A recent\nmeasurement of the optical conductivity in graphene [P. Gallagher et.al,\nScience 364, 158 (2019)] offers a possibility of experimental determination of\nmicroscopic time scales describing scattering processes in the electronic\nfluid. In this paper, I report a theoretical calculation of the optical\nconductivity in graphene at arbitrary doping levels, within the whole\n\"hydrodynamic\" temperature range, and for arbitrary, non-quantizing magnetic\nfields. The obtained results are in good agreement with the available\nexperimental data.",
        "positive": "Optical control of individual carbon nanotube light emitters by spectral\n  double resonance in silicon microdisk resonators: Single-walled carbon nanotubes have advantages as a nanoscale light source\ncompatible with silicon photonics because they show room-temperature\nluminescence at telecom-wavelengths and can be directly synthesized on silicon\nsubstrates. Here we demonstrate integration of individual light-emitting carbon\nnanotubes with silicon microdisk resonators. Photons emitted from nanotubes are\nefficiently coupled to whispering gallery modes, circulating within the disks\nand lighting up their perimeters. Furthermore, we control such emission by\ntuning the excitation wavelength in and out of resonance with higher order\nmodes in the same disk. Our results open up the possibilities of using nanotube\nemitters embedded in photonic circuits that are individually addressable\nthrough spectral double resonance."
    },
    {
        "anchor": "Evidence for Fast Interlayer Energy Transfer in MoSe2/WS2\n  Heterostructures: Strongly bound excitons confined in two-dimensional (2D) semiconductors are\ndipoles with a perfect in-plane orientation. In a vertical stack of\nsemiconducting 2D crystals, such in-plane excitonic dipoles are expected to\nefficiently couple across van der Waals gap due to strong interlayer Coulomb\ninteraction and exchange their energy. However, previous studies on\nheterobilayers of group 6 transition metal dichalcogenides (TMDs) found that\nthe exciton decay dynamics is dominated by interlayer charge transfer (CT)\nprocesses. Here, we report an experimental observation of fast interlayer\nenergy transfer (ET) in MoSe2/WS2 heterostructures using photoluminescence\nexcitation (PLE) spectroscopy. The temperature dependence of the transfer rates\nsuggests that the ET is F\\\"orster-type involving excitons in the WS2 layer\nresonantly exciting higher-order excitons in the MoSe2 layer. The estimated ET\ntime of the order of 1 ps is among the fastest compared to those reported for\nother nanostructure hybrid systems such as carbon nanotube bundles. Efficient\nET in these systems offers prospects for optical amplification and energy\nharvesting through intelligent layer engineering.",
        "positive": "Enhanced superconducting proximity effect in clean ferromagnetic domain\n  structures: We investigate the superconducting proximity effect in a clean magnetic\nstructure consisting of two ferromagnetic layered domains with antiparallel\nmagnetizations in contact with a superconductor. Within the quasiclassical\nGreen's function approach we find that the penetration of the superconducting\ncorrelations into the magnetic domains can be enhanced as compared to the\ncorresponding single domain structure. This enhancement depends on an effective\nexchange field which is determined by the thicknesses and the exchange fields\nof the two domains. The pair amplitude function oscillates spatially inside\neach domain with a period inversely proportional to the local exchange field.\nWhile the oscillations have a decreasing amplitude with distance inside the\ndomain which is attached to the superconductor, they are enhancing in the other\ndomain and can reach the corresponding normal metal value for a zero effective\nexchange field. We also find that the corresponding oscillations in the Fermi\nlevel proximity density of states as a function of the second domain's\nthickness has an growing amplitude over a range which depends on the effective\nexchange field. Our findings can be explained as the result of cancellation of\nthe exchange fields induced phases gained by an electron inside the two domains\nwith antiparallel magnetizations."
    },
    {
        "anchor": "Sub-Poissonian phononic population in a nanoelectromechanical system: Population of a phononic mode coupled to a single-electron transistor in the\nsequential tunneling regime is discussed for the experimentally realistic case\nof intermediate electron-phonon coupling. Features like a sub-Poissonian\nbosonic distribution are found in regimes where electron transport drives the\noscillator strongly out of equilibrium with only few phonon states selectively\npopulated. The electron Fano factor is compared to fluctuations in the phonon\ndistribution, showing that all possible combinations of sub- and\nsuper-Poissonian character can be realized.",
        "positive": "Non linear transport in drift-diffusion equations under magnetic field: We analyze numerically and analytically the non linear transport properties\nof a drift-diffusion equation in presence of a magnetic field and of a disorder\npotential. For a wide range of parameters this model exhibits a plateau where\nthe drift velocity is almost independent on the applied electric field. This\nbehavior has strong similarities with the zero differential resistance states\nobserved experimentally in high mobility two dimensional systems. Performed\nnumerical simulations are in a good global agreement with the developed\nanalytical theory even if the later leads to overestimated negative\ndifferential resistance values."
    },
    {
        "anchor": "A theoretical model for single molecule incoherent scanning tunneling\n  spectroscopy: Single molecule scanning tunneling spectroscopy (STS), with dephasing due to\nelastic and inelastic scattering, is of some current interest. Motivated by\nthis, we report an extended Huckel theory (EHT) based mean-field\nNon-equilibrium Green's function (NEGF) transport model with electron-phonon\nscattering treated within the self-consistent Born approximation (SCBA).\nFurthermore, a procedure based on EHT basis set modification is described. We\nuse this model to study the effect of the temperature dependent dephasing, due\nto low lying modes in far-infrared range for which hw<<kT, on the resonant\nconduction through highest occupied molecular orbital (HOMO) level of a phenyl\ndithiol molecule sandwiched between two fcc-Au(111) contacts. Furthermore, we\npropose to include dephasing in room temperature molecular resonant conduction\ncalculations.",
        "positive": "Torsional Response and Dissipationless Viscosity in Topological\n  Insulators: We consider the visco-elastic response of the electronic degrees of freedom\nin 2D and 3D topological insulators (TI). Our primary focus is on the 2D Chern\ninsulator which exhibits a bulk dissipationless viscosity analogous to the\nquantum Hall viscosity predicted in integer and fractional quantum Hall states.\nWe show that the dissipationless viscosity is the response of a TI to torsional\ndeformations of the underlying lattice geometry. The visco-elastic response\nalso indicates that crystal dislocations in Chern insulators will carry\nmomentum density. We briefly discuss generalizations to 3D which imply that\ntime-reversal invariant TI's will exhibit a quantum Hall viscosity on their\nsurfaces."
    },
    {
        "anchor": "Structure and stability of graphene nanoribbons in oxygen, carbon\n  dioxide, water, and ammonia: We determine, by means of density functional theory, the stability and the\nstructure of graphene nanoribbon (GNR) edges in presence of molecules such as\noxygen, water, ammonia, and carbon dioxide. As in the case of\nhydrogen-terminated nanoribbons, we find that the most stable armchair and\nzigzag configurations are characterized by a non-metallic/non-magnetic nature,\nand are compatible with Clar's sextet rules, well known in organic chemistry.\nIn particular, we predict that, at thermodynamic equilibrium, neutral GNRs in\noxygen-rich atmosphere should preferentially be along the armchair direction,\nwhile water-saturated GNRs should present zigzag edges. Our results promise to\nbe particularly useful to GNRs synthesis, since the most recent and advanced\nexperimental routes are most effective in water and/or ammonia-containing\nsolutions.",
        "positive": "Heat transport in carbon nanotubes: Length dependence of phononic\n  conductivity from the Boltzmann transport equation and molecular dynamics: In this article, we address lattice heat transport in single-walled carbon\nnanotubes (CNTs) by a quantum mechanical calculation of three-phonon scattering\nrates in the framework of the Boltzmann transport equation (BTE) and classical\nmolecular dynamics (MD) simulation. Under a consistent choice of an empirical,\nrealistic atomic interaction potential, we compare the tube length dependence\nof the lattice thermal conductivity (TC) at room temperature determined from an\niterative solution of the BTE and from a nonequilibrium MD (NEMD) approach.\nQualitatively similar trends are found in the limit of short tubes, where an\nextensive regime of ballistic heat transport prevailing in CNTs of lengths\n$L\\lesssim 1\\,\\rm{\\mu m}$ is independently confirmed. In the limit of long\ntubes, the BTE approach suggests a saturation of TC with tube length, whereas\ndirect NEMD simulations of tubes extending up to $L=10\\,\\rm{\\mu m}$ are\ndemonstrated to be insufficient to settle the question of whether a fully\ndiffusive heat transport regime and an intrinsic value of TC exist for CNTs.\nNoting that acoustic phonon lifetimes lie at the heart of a saturation of TC\nwith tube length as per the BTE framework, we complement the quantum mechanical\nprediction of acoustic phonon lifetimes with an analysis of phonon modes in the\nframework of equilibrium MD (EMD). A normal mode analysis (NMA) with an\nemphasis on long wavelength acoustic modes corroborates the BTE prediction that\nheat transport in CNTs in the long tube limit is governed by the low\nattenuation rates of longitudinal and twisting phonons."
    },
    {
        "anchor": "Switching between attractive and repulsive Coulomb-interaction-mediated\n  drag in an ambipolar GaAs/AlGaAs bilayer device: We present measurements of Coulomb drag in an ambipolar GaAs/AlGaAs double\nquantum well structure that can be configured as both an electron-hole bilayer\nand a hole-hole bilayer, with an insulating barrier of only 10 nm between the\ntwo quantum wells. The Coulomb drag resistivity is a direct measure of the\nstrength of the interlayer particle-particle interactions. We explore the\nstrongly interacting regime of low carrier densities (2D interaction parameter\n$r_s$ up to 14). Our ambipolar device design allows comparison between the\neffects of the attractive electron-hole and repulsive hole-hole interactions,\nand also shows the effects of the different effective masses of electrons and\nholes in GaAs.",
        "positive": "Quantum Conductance of the Single Electron Transistor: The quantum conductance of the single-electron tunneling (SET) transistor is\ninvestigated in this paper by the functional integral approach. The formalism\nis valid for arbitrary tunnel resistance of the junctions forming the SET\ntransistor at any temperature. The path integrals are evaluated by the\nsemiclassical method to yield an explicit non-perturbation form of the quantum\nconductance of the SET transistor. An anomaly of the quantum conductance is\nfound if the tunnel resistances are much smaller than the quantum resistance.\nThe dependence of the conductance on the gate voltage is also discussed."
    },
    {
        "anchor": "The low-temperature expansion of the Casimir-Polder free energy of an\n  atom with graphene: We consider the low-temperature expansion of the Casimir-Polder free energy\nfor an atom and graphene by using the Poisson representation of the free\nenergy. We extend our previous analysis on the different relations between\nchemical potential $\\mu$ and mass gap parameter $m$. The key role plays the\ndependence of graphene conductivities on the $\\mu$ and $m$. For simplicity, we\nmade the manifest calculations for zero values of the Fermi velocity. For $\\mu\n>m$ the thermal correction $\\sim T^2$ and for $\\mu < m$ we confirm the recent\nresult of Klimchitskaya and Mostepanenko, that the thermal correction $\\sim\nT^5$. In the case of exact equality $\\mu =m$ the correction $\\sim T$. This\npoint is unstable and the system falls to the regime with $\\mu >m$ or $\\mu <m$.\nThe analytical calculations are illustrated by numerical evaluations for the\nHydrogen atom/graphene system.",
        "positive": "Magnetotransport in Quasilattices: The dc conductance and the Hall voltage of planar arrays of interconnected\nquantum wires are calculated numerically. Our systems are derived from finite\npatches of aperiodic graphs, with completely symmetric scatterers placed on\ntheir vertices which are interconnected by ideal quantum wires. Already in a\nperiodic square lattice arrangement, quantum interference effects lead to\ncomplicated magnetotransport properties related to the Hofstadter butterfly.\nFor rectangular Fibonacci grids and other quasiperiodic lattices, we obtain\nstill more complex fractal patterns. In particular, irrational ratios of edge\nlengths and of tile areas in our samples destroy the periodicities with respect\nto the Fermi wave vector and the magnetic flux, respectively."
    },
    {
        "anchor": "Sequential resonant tunneling in quantum cascade lasers: A model of sequential resonant tunneling transport between two-dimensional\nsubbands that takes into account explicitly elastic scattering is investigated.\nIt is compared to transport measurements performed on quantum cascade lasers\nwhere resonant tunneling processes are known to be dominating. Excellent\nagreement is found between experiment and theory over a large range of current,\ntemperature and device structures.",
        "positive": "Part II: Witten effect and $\\mathbb{Z}$-classification of axion angle\n  $\u03b8=n \u03c0$: The non-trivial third homotopy class of three-dimensional topological\ninsulators leads to quantized, magneto-electric coefficient or axion angle\n$\\theta= n \\pi$, with $n \\in \\mathbb{Z}$. In Part I, we developed tools for\ncomputing $n$ from a staggered symmetry-indicator $\\kappa_{AF,j}$ and Wilson\nloops of non-Abelian, Berry connection in momentum-space, which clearly\ndistinguished between magneto-electrically trivial ($n=0$), and non-trivial\n($n=2s$) topological crystalline insulators. In this work, we perform\n$\\mathbb{Z}$-classification of real-space, topological response or $\\theta$ by\ncarrying out thought experiments with magnetic, Dirac monopoles. We demonstrate\nthis for non-magnetic and magnetic topological insulators by computing induced\nelectric charge on monopoles or Witten effect. We show that both first- and\nhigher- order topological insulators can exhibit quantized, magneto-electric\nresponse, irrespective of the presence of gapless surface-states, and\ncorner-states. Special attention is paid to the response of octupolar\nhigher-order topological insulator, which was originally predicted to be\nmagneto-electrically trivial. The important roles of fermion zero-modes,\n$\\mathcal{CP}$, and flavor symmetries are critically addressed. Our work\noutlines a unified theoretical framework for addressing dc topological response\nand topological quantum phase transitions, which cannot be reliably predicted\nby symmetry-based classification scheme."
    },
    {
        "anchor": "Electrically tunable valley polarization in Weyl semimetals with tilted\n  energy dispersion: Tunneling transport across the p-n-p junction of Weyl semimetal with tilted\nenergy dispersion is investigated. We report that the electrons around\ndifferent valleys experience opposite direction refractions at the barrier\ninterface when the energy dispersion is tilted along one of the transverse\ndirections. Chirality dependent refractions at the barrier interface polarize\nthe Weyl fermions in angle-space according to their valley index. A real\nmagnetic barrier configuration is used to select allowed transmission angles,\nwhich results in electrically controllable and switchable valley polarization.\nOur findings may pave the way for experimental investigation of valley\npolarization, as well as valleytronic and electron optic applications in Weyl\nsemimetals.",
        "positive": "Integer Quantum Hall Effect in Trilayer Graphene: The Integer Quantum Hall Effect (IQHE) is a distinctive phase of\ntwo-dimensional electronic systems subjected to a perpendicular magnetic field.\nThus far, the IQHE has been observed in semiconductor heterostructures and in\nmono- and bi-layer graphene. Here we report on the IQHE in a new system:\ntrilayer graphene. Experimental data are compared with self-consistent Hartree\ncalculations of the Landau levels for the gated trilayer. The plateau structure\nin the Hall resistivity determines the stacking order (ABA versus ABC). We find\nthat the IQHE in ABC trilayer graphene is similar to that in the monolayer,\nexcept for the absence of a plateau at filling factor v=2. At very low filling\nfactor, the Hall resistance vanishes due to the presence of mixed electron and\nhole carriers induced by disorder."
    },
    {
        "anchor": "Interface control of the magnetic chirality in TaN|CoFeB|MgO\n  heterosctructures: Recent advances in the understanding of spin orbital effects in ultrathin\nmagnetic heterostructures have opened new paradigms to control magnetic moments\nelectrically. The Dzyaloshinskii-Moriya interaction (DMI) is said to play a key\nrole in forming a Neel-type domain wall that can be driven by the spin Hall\ntorque, a torque resulting from the spin current generated in a neighboring\nnon-magnetic layer via the spin Hall effect. Here we show that the sign of the\nDMI, which determines the direction to which a domain wall moves with current,\ncan be changed by modifying the adjacent non-magnetic layer. We find that the\nsense of rotation of a domain wall spiral is reversed when the Ta underlayer is\ndoped with nitrogen in Ta|CoFeB|MgO heterostructures. The spin Hall angle of\nthe Ta and nitrogen doped Ta underlayers carry the same sign, suggesting that\nthe sign of the DMI is defined at the interface. Depending on the sense of\nrotation, spin transfer torque and spin Hall torque can either compete or\nassist each other, thus influencing the efficiency of moving domain walls with\ncurrent.",
        "positive": "SU(4) Skyrmions in the $\u03bd=\\pm 1$ Quantum Hall State of Graphene: We explore different skyrmion types in the lowest Landau level of graphene at\na filling factor $\\nu=\\pm 1$. In addition to the formation of spin and valley\npseudospin skyrmions, we show that another type of spin-valley entangled\nskyrmions can be stabilized in graphene due to an approximate SU(4) spin-valley\nsymmetry that is affected by sublattice symmetry-breaking terms. These\nskyrmions have a clear signature in spin-resolved density measurements on the\nlattice scale, and we discuss the expected patterns for the different skyrmion\ntypes."
    },
    {
        "anchor": "Spin Hall effect at interfaces between HgTe/CdTe quantum wells and\n  metals: We study the spin-dependent transmission through interfaces between a\nHgTe/CdTe quantum well (QW) and a metal - both for the normal metal and the\nsuperconducting case. Interestingly, we discover a new type of spin Hall effect\nat these interfaces that happens to exist even in the absence of structure and\nbulk inversion asymmetry within each subsystem (i.e. the QW and the metal).\nThus, this is a pure boundary spin Hall effect which can be directly related to\nthe existence of exponentially localized edge states at the interface. We\ndemonstrate how this effect can be measured and functionalized for an\nall-electric spin injection into normal metal leads.",
        "positive": "A silicon-based single-electron interferometer coupled to a fermionic\n  sea: We study Landau-Zener-Stueckelberg-Majorana (LZSM) interferometry under the\ninfluence of projective readout using a charge qubit tunnel-coupled to a\nfermionic sea. This allows us to characterise the coherent charge qubit\ndynamics in the strong-driving regime. The device is realised within a silicon\ncomplementary metal-oxide-semiconductor (CMOS) transistor. We first read out\nthe charge state of the system in a continuous non-demolition manner by\nmeasuring the dispersive response of a high-frequency electrical resonator\ncoupled to the quantum system via the gate. By performing multiple fast\npassages around the qubit avoided crossing, we observe a multi-passage LZSM\ninterferometry pattern. At larger driving amplitudes, a projective measurement\nto an even-parity charge state is realised, showing a strong enhancement of the\ndispersive readout signal. At even larger driving amplitudes, two projective\nmeasurements are realised within the coherent evolution resulting in the\ndisappearance of the interference pattern. Our results demonstrate a way to\nincrease the state readout signal of coherent quantum systems and replicate\nsingle-electron analogues of optical interferometry within a CMOS transistor."
    },
    {
        "anchor": "Quantum optical interface for gate-controlled spintronic devices: We describe an opto-electronic structure in which charge and spin degrees of\nfreedom in electrical gate-defined quantum dots can be coherently coupled to\nlight. This is achieved via electron-electron interaction or via electron\ntunneling into a proximal self-assembled quantum dot. We illustrate potential\napplications of this approach by considering several quantum control\ntechniques, including optical read-out of gate-controlled semiconductor quantum\nbits and controlled generation of entangled photon-spin pairs.",
        "positive": "Strain-gradient induced topological transition in bent nanoribbons of\n  the Dirac semimetal Cd3As2: Dirac semimetal is an ideal parent state to realize various exotic states of\nmatters, such as quantum spin Hall state, Weyl semimetal phase and Majorana\nzero modes. Topological phase transition allows for the switching between these\ndifferent topological states. Here, in this paper, we exhibit experimentally an\neffective approach of inducing topological phase transition in Cd3As2\nnanoribbons, by applying a bending strain profile onto the sample. The local\nstrain varies linearly from compression to tension through the cross-section of\na bent nanoribbon. The strain gradient causes obvious lattice deformation and\nbreaks the C4 rotational symmetry, thus opening an energy gap at the Dirac\npoints and making the bulk gapful. When further increasing the strain strength,\nthe local strain effect dominates over the symmetry-breaking effect, where\nspatially-varying band shift becomes prominent across the nanoribbon. Our\nresults demonstrate the effect of strain gradient on the evolution of energy\nband structures, which should be valuable for further study of strain-mediated\ntopological phase transition."
    },
    {
        "anchor": "Local Spin Susceptibilities of Low-Dimensional Electron Systems: We investigate, assess, and suggest possibilities for a measurement of the\nlocal spin susceptibility of a conducting low-dimensional electron system. The\nbasic setup of the experiment we envisage is a source-probe one. Locally\ninduced spin density (e.g. by a magnetized atomic force microscope tip) extends\nin the medium according to its spin susceptibility. The induced magnetization\ncan be detected as a dipolar magnetic field, for instance, by an\nultra-sensitive nitrogen-vacancy center based detector, from which the spatial\nstructure of the spin susceptibility can be deduced. We find that\none-dimensional systems, such as semiconducting nanowires or carbon nanotubes,\nare expected to yield a measurable signal. The signal in a two-dimensional\nelectron gas is weaker, though materials with high enough $g$-factor (such as\nInGaAs) seem promising for successful measurements.",
        "positive": "Unconventional topological phase transitions in helical Shiba chains: Chains of magnetic impurities placed on a superconducting substrate and\nforming helical spin order provide a promising venue for realizing a\ntopological superconducting phase. An effective tight-binding description of\nsuch helical Shiba chains involves long-range (power-law) hopping and pairing\namplitudes which induce an unconventional topological critical point. At the\ncritical point, we find exponentially localized Majorana bound states with a\nshort localization length unrelated to a topological gap. Away from the\ncritical point, this exponential decay develops a power-law tail. Our\nanalytical results have encouraging implications for experiment."
    },
    {
        "anchor": "Two-dimensional few electron systems in high magnetic fields:\n  Composite-fermion or rotating-electron-molecule approach?: A new class of analytic and parameter-free, strongly correlated wave\nfunctions of simple functional form is derived for few electrons in\ntwo-dimensional quantum dots under high magnetic fields. These wave functions\nare constructed through breaking and subsequent restoration of the circular\nsymmetry, and they offer a natural alternative to the Laughlin and\ncomposite-fermion functions. Underlying our approach is a\ncollectively-rotating-electron-molecule picture. The angular momenta allowed by\nmolecular symmetry correspond to the filling-factors' hierarchy of the\nfractional quantum Hall effect.",
        "positive": "Tunneling magnetoresistance in ensembles of ferromagnetic granules with\n  exchange interaction and random easy axes of magnetic anisotropy: We study the tunneling magnetoresistance in the ensembles of ferromagnetic\ngranules with random easy axes of magnetic anisotropy taking into account the\nexchange interaction between granules. It is shown that due to the exchange\ninteraction magnetoresistance is effectively decoupled from magnetization, i.e.\nthe strongest negative magnetoresistance can be observed at the field where\nmagnetization is almost saturated. Under some conditions, the sign of\nmagnetoresistance can be reversed and tunneling magnetoresistance can become\npositive at certain magnetic fields. Our theory agrees with measurements of\nmagnetoresistance in ensembles of Fe granules in SiCxNy matrix."
    },
    {
        "anchor": "Coherent quantum transport in disordered systems I: The influence of\n  dephasing on the transport properties and absorption spectra on\n  one-dimensional systems: Excitonic transport in static disordered one dimensional systems is studied\nin the presence of thermal fluctuations that are described by the\nHaken-Strobl-Reineker model. For short times, non-diffusive behavior is\nobserved that can be characterized as the free-particle dynamics in the\nAnderson localized system. Over longer time scales, the environment-induced\ndephasing is sufficient to overcome the Anderson localization caused by the\ndisorder and allow for transport to occur which is always seen to be diffusive.\nIn the limiting regimes of weak and strong dephasing quantum master equations\nare developed, and their respective scaling relations imply the existence of a\nmaximum in the diffusion constant as a function of the dephasing rate that is\nconfirmed numerically. In the weak dephasing regime, it is demonstrated that\nthe diffusion constant is proportional to the square of the localization length\nwhich leads to a significant enhancement of the transport rate over the\nclassical prediction. Finally, the influence of noise and disorder on the\nabsorption spectrum is presented and its relationship to the transport\nproperties is discussed.",
        "positive": "Steering internal and outgoing electron dynamics in bilayer graphene\n  cavities by cavity design: Ballistic, gate-defined devices in two-dimensional materials offer a platform\nfor electron optics phenomena influenced by the material's properties and gate\ncontrol. We study the ray trajectory dynamics of all-electronic, gate-defined\ncavities in bilayer graphene to establish how distinct regimes of the internal\nand outgoing charge carrier dynamics can be tuned and optimized by the cavity\nshape, symmetry, and parameter choice, e.g., the band gap and the cavity\norientation. In particular, we compare the dynamics of two cavity shapes,\no'nigiri, and Lima\\c{c}on cavities, which fall into different symmetry classes.\nWe demonstrate that for stabilising regular, internal cavity modes, such as\nperiodic and whispering gallery orbits, it is beneficial to match the cavity\nshape to the bilayer graphene Fermi line contour. Conversely, a cavity of a\ndifferent symmetry than the material dispersion allows one to determine\npreferred emission directionalities in the emitted far-field."
    },
    {
        "anchor": "All-plasmonic switching effect in the graphene nanostructures containing\n  quantum emitters: Nonlinear plasmonic effects in perspective 2D materials containing\nlow-dimensional quantum emitters can be a basis of a novel technological\nplatform for the fabrication of fast all-plasmonic triggers, transistors, and\nsensors. This article considers the conditions for achieving a strong\nplasmon-exciton coupling in the system with quantum nanowire (NW) placed in\nproximity to the nanostructured graphene sheets. In the condition of strong\ncoupling, nonlinear interaction between two surface plasmon-polariton (SPP)\nmodes propagating along the graphene waveguide integrated with a stub\nnanoresonator loaded with a core-shell semiconductor NWs is investigated. Using\nthe 2D full-wave electromagnetic simulation, we studied the different\ntransmittance regimes of the stub with NW for both the strong pump SPP and weak\nsignal SPP tuned to interband and intraband transition in NW, respectively. We\nfound such a regime of NW-SPP interaction that corresponds to the destructive\ninterference with the signal SPP transmittance through the stub less than 7% in\nthe case for pump SPP to be turned off. In contrast, the turning on the pump\nSPP leads to a transition to constructive interference in the stub and\nenhancement of signal SPP transmittance to 93%. In our model, the effect of\nplasmonic switching occurs with a rate of 50 GHz at wavelength 8 um for signal\nSPP localized inside 20 nm graphene stub loaded with core-shell InAs/ZnS NW.",
        "positive": "Ac-cotunneling through an interacting quantum dot under a magnetic field: We analyze inelastic cotunneling through an interacting quantum dot subject\nto an ambient magnetic field in the weak tunneling regime under a non-adiabatic\ntime-dependent bias-voltage. Our results clearly exhibit photon-assisted\nsatellites and an overall suppression of differential conductance with\nincreasing driving amplitude, which is consistent with experiments. We also\npredict a zero-anomaly in differential conductance under an appropriate driving\nfrequency."
    },
    {
        "anchor": "Polarization rotation and Casimir effect in suspended graphene films: The low-energy quasi-excitations in graphene are known to be described as\nDirac fermions in 2+1 dimensions. Adopting field-theoretical approach we\ninvestigate the interaction of these quasi-particles with 3+1 dimensional\nelectromagnetic field focusing on the optical properties of suspended graphene\nlayers and their Casimir interaction with ideal conductor. The magnitude of\npredicted effects (the rotation of polarization of light and the Casimir force)\nappears to be well within modern experimental capabilities.",
        "positive": "Magnetic susceptibility of topological nodal semimetals: Magnetic susceptibility of the topological Weyl, type-II Weyl, Dirac, and\nline node semimetals is theoretically investigated. Dependences of this\nsusceptibility on the chemical potential, temperature, direction and magnitude\nof the magnetic field are found. The obtained results show that magnetic\nmeasurements can be very useful in investigating these semimetals. As an\nexample, we calculate magnetic susceptibility of Cd$_3$As$_2$, Na$_3$Bi, and\nCa$_3$P$_2$."
    },
    {
        "anchor": "Floquet topological insulators: from band structure engineering to novel\n  non-equilibrium quantum phenomena: We review methods for using time-periodic fields (e.g., laser or microwave\nfields) to induce non-equilibrium topological phenomena in quantum many-body\nsystems. We discuss how such fields can be used to change the topological\nproperties of the single particle spectrum, and key experimental demonstrations\nin solid state, cold atomic, and photonic systems. The single particle Floquet\nband structure provides a stage on which the system's dynamics play out; the\ncrucial question is then how to obtain robust topological behaviour in the\nmany-particle setting. In the regime of mesoscopic transport, we discuss\nmanifestations of topological edge states induced in the Floquet spectrum.\nOutside the context of mesoscopic transport, the main challenge of inducing\nstable topological phases in many-body Floquet systems is their tendency to\nabsorb energy from the drive and thereby to heat up. We discuss three routes to\novercoming this challenge: long-lived transient dynamics and prethermalization,\ndisorder-induced many-body localization, and engineered couplings to external\nbaths. We discuss the types of phenomena that can be explored in each of these\nregimes, and their experimental realizations.",
        "positive": "Percolation conductivity in hafnium sub-oxides: In this study, we demonstrated experimentally that formation of chains and\nislands of oxygen vacancies in hafnium sub-oxides (HfO$_x$, $x<2$) leads to\npercolation charge transport in such dielectrics. Basing on the model of\n\\'{E}fros-Shklovskii percolation theory good quantitative agreement between the\nexperimental and theoretical data of current-voltage characteristics were\nachieved. Based on the percolation theory suggested model shows that hafnium\nsub-oxides consist of mixtures of metallic Hf nanoscale clusters of 1-2 nm\ndistributed onto non-stoichiometric HfO$_x$. It was shown that reported\napproach might describe low resistance state current-voltage characteristics of\nresistive memory elements based on HfO$_x$."
    },
    {
        "anchor": "Schottky barriers in carbon nanotube heterojunctions: We investigate electronic properties of heterojunctions between metallic and\nsemiconducting single-wall carbon nanotubes. Ineffective screening of the long\nrange Coulomb interaction in one-dimensional nanotube systems drastically\nmodifies the charge transfer phenomena compared to conventional semiconductor\nheterostructures. The length of depletion region varies over a wide range (from\nthe nanotube radius to the nanotube length) sensitively depending on the doping\nstrength. The Schottky barrier gives rise to the asymmetry of the I-V\ncharacteristics of heterojunctions, in agreement with recent experimental\nresults by Yao {\\it et al.} and Fuhrer {\\it et al.} Dynamic charge build-up\nnear the junction results in a step-like growth of the current at reverse bias.",
        "positive": "Ultrawide Frequency Tuning of Atomic Layer van der Waals Heterostructure\n  Electromechanical Resonators: We report on the experimental demonstration of atomically thin molybdenum\ndisulfide (MoS2)-graphene van der Waals (vdW) heterostructure\nnanoelectromechanical resonators with ultrawide frequency tuning. With direct\nelectrostatic gate tuning, these vdW resonators exhibit exceptional tunability,\nin general, {\\Delta}f/f0 >200%, for continuously tuning the same device and the\nsame mode (e.g., from ~23 to ~107MHz), up to {\\Delta}f/f0 = 370%, the largest\nfractional tuning range in such resonators to date. This remarkable\nelectromechanical resonance tuning is investigated by two different analytical\nmodels and finite element simulations. Further, we carefully perform clear\ncontrol experiments and simulations to elucidate the difference in frequency\ntuning between heterostructure and single-material resonators. At a given\ninitial strain level, the tuning range depends on the two-dimensional (2D)\nYoung's moduli of the constitutive crystals; devices built on materials with\nlower 2D moduli show wider tuning ranges. This study exemplifies that vdW\nheterostructure resonators can retain unconventionally broad, continuous\ntuning, which is promising for voltage-controlled, tunable nanosystems."
    },
    {
        "anchor": "Electroluminescence spectra in weakly coupled single-molecule junctions: We have combined ab initio quantum chemistry calculations with a\nrate-equation formalism to analyze electroluminescence spectra in\nsingle-molecule junctions, measured recently by several groups in Scanning\nTunneling Microscope setups. In our method, the entire vibrational spectrum is\ntaken into account. Our method leads to good quantitative agreement with both\nthe spectroscopic features of the measurements and their current and voltage\ndependence. Moreover, our method is able to explain several previously\nunexplained features. We show that in general, the quantum yield is expected to\nbe suppressed at high bias, as is observed in one of the measurements.\nAdditionally, we comment on the influence of the vibrational relaxation times\non several features of the spectrum.",
        "positive": "Theory of coupled spin-charge transport due to spin-orbit interaction in\n  inhomogeneous two-dimensional electron liquids: Spin-orbit interactions in two-dimensional electron liquids are responsible\nfor many interesting transport phenomena in which particle currents are\nconverted to spin polarizations and spin currents and viceversa. Prime examples\nare the spin Hall effect, the Edelstein effect, and their inverses. By similar\nmechanisms it is also possible to partially convert an optically induced\nelectron-hole density wave to a spin density wave and viceversa. In this paper\nwe present a unified theoretical treatment of these effects based on quantum\nkinetic equations that include not only the intrinsic spin-orbit coupling from\nthe band structure of the host material, but also the spin-orbit coupling due\nto an external electric field and a random impurity potential. The\ndrift-diffusion equations we derive in the diffusive regime are applicable to a\nbroad variety of experimental situations, both homogeneous and non-homogeneous,\nand include on equal footing \"skew scattering\" and \"side-jump\" from\nelectron-impurity collisions. As a demonstration of the strength and usefulness\nof the theory we apply it to the study of several effects of current\nexperimental interest: the inverse Edelstein effect, the spin-current swapping\neffect, and the partial conversion of an electron-hole density wave to a spin\ndensity wave in a two-dimensional electron gas with Rashba and Dresselhaus\nspin-orbit couplings, subject to an electric field."
    },
    {
        "anchor": "Voltage-controlled spin injection with an endohedral fullerene\n  CoC$_{60}$ dimer: Spin-dependent transport through an endohedral fullerene Co@C$_{60}$ dimer\nwith gold electrodes is explored theoretically using density functional and\nextended H\\\"{u}ckel theory. Density of states spin polarizations up to 95%, due\nto spin-splitting of Co 3d orbitals, are found by varying the gate and/or bias\nvoltage. The current-voltage characteristics and strong (up to 100%) spin\npolarization of the current indicate that the device can be utilized for highly\nefficient spin injection into nonmagnetic conductors. This finding opens the\nway to the realization of electrostatically tuned spintronic nano devices less\nthan 2 nanometers in size, without ferromagnetic electrodes.",
        "positive": "The structure and properties of graphene supported on gold nanoparticles: Graphene covered metal nanoparticles constitute a novel type of hybrid\nmaterials, which provide a unique platform to study plasmonic effects,\nsurface-enhanced Raman scattering (SERS), and metal-graphene interactions at\nthe nanoscale. Such a hybrid material is fabricated by transferring graphene\ngrown by chemical vapor deposition onto closely spaced gold nanoparticles\nproduced on a silica wafer. The morphology and physical properties of\nnanoparticle-supported graphene is investigated by atomic force microscopy,\noptical reflectance spectroscopy, scanning tunneling microscopy and\nspectroscopy (STM/STS), and confocal Raman spectroscopy. This study shows that\nthe graphene Raman peaks are enhanced by a factor which depends on the\nexcitation wavelength, in accordance with the surface plasmon resonance of the\ngold nanoparticles, and also on the graphene-nanoparticle distance which is\ntuned by annealing at moderate temperatures. The observed SERS activity is\ncorrelated to the nanoscale corrugation of graphene. STM and STS measurements\nshow that the local density of electronic states in graphene is modulated by\nthe underlying gold nanoparticles."
    },
    {
        "anchor": "Superlattices of Bi2Se3/In2Se3: Growth Characteristics and Structural\n  Properties: Superlattices (SLs) consisted of alternating Bi2Se3 and In2Se3 layers are\ngrown on Si(111) by molecular-beam epitaxy. Bi2Se3, a three-dimensional\ntopological insulator (TI), showed good chemical and structural compatibility\nwith In2Se3, a normal band insulator with large energy bandgap. The individual\nlayers in the SLs are very uniform and the hetero-interfaces are sharp.\nTherefore, such SL structures are potential candidates for explorations of the\nquantum size effects of TIs.",
        "positive": "Optimal Control of the Operating Regime of a Single Electron Double\n  Quantum Dot: The double quantum dot device benefits from the advantages of both the spin\nand charge qubits, while offering ways to mitigate their drawbacks. Careful\ngate voltage modulation can grant greater spinlike or chargelike dynamics to\nthe device, yielding long coherence times with the former and high electrical\nsusceptibility with the latter for electrically driven spin rotations or\ncoherent interactions with microwave photons. We show that optimal control\npulses generated using the GRadient Ascent Pulse Engineering (GRAPE) algorithm\ncan yield higher-fidelity operating regime transfers than can be achieved using\nlinear methods."
    },
    {
        "anchor": "Device Engineering of Perovskite Solar Cells to Achieve Near Ideal\n  Efficiency: Despite the exciting recent research on perovskite based solar cells, the\ndesign space for further optimization and the practical limits of efficiency\nare not well known in the community. In this manuscript, we address these\naspects through theoretical calculations and detailed numerical simulations.\nHere, we first provide the detailed balance limit efficiency in the presence of\nradiative and Auger recombination. Then, using coupled optical and carrier\ntransport simulations, we identify the physical mechanisms that contribute\ntowards bias dependent carrier collection, and hence low fill factors of\ncurrent perovskite based solar cells. Curiously, we find that while Auger\nrecombination is not a dominant factor at the detailed balance limit, it plays\na significant role in device level implementations. Surprisingly, our device\ndesigns indicate that it is indeed possible to achieve efficiency and fill\nfactor greater than 25% and 85%, respectively - even in the presence of Auger\nrecombination.",
        "positive": "Advances in dynamic AFM: from nanoscale energy dissipation to material\n  properties in the nanoscale: Since the inception of the atomic force microscope AFM, dynamic methods have\nbeen very fruitful by establishing methods to quantify dissipative and\nconservative forces in the nanoscale and by providing a means to apply gentle\nforces to the samples with high resolution. Here we review developments that\ncover over a decade of our work on energy dissipation, phase contrast and the\nextraction of relevant material properties from observables. We describe the\nattempts to recover material properties via one dimensional amplitude and phase\ncurves from force models and explore the evolution of these methods in terms of\nforce reconstruction, fits of experimental measurements, and the more recent\nadvances in multifrequency AFM."
    },
    {
        "anchor": "Reply to Comment by D. Spemann et al [EPL 98 (2012) 57006,\n  arXiv:1204.2992]: This article is a reply to the Comment by D. Spemann et al (arXiv:1204.2992)\nin response to our paper 'Revealing common artifacts due to ferromagnetic\ninclusions in highly oriented pyrolytic graphite' (EPL, 97 (2012) 47001).",
        "positive": "Closed pi-electron Network in Large Polyhedral Multi-shell Carbon\n  Nanoparticles: High Resolution Transmission Electron Microscopy (HRTEM), X-ray Diffraction\n(XRD) and Raman spectroscopy reveal a polyhedral multi-shell fullerene-like\nstructure of astralen carbon nanoparticles. The polyhedra consist of large flat\ngraphitic faces connected by defective edge regions with presumably\npentagon-like structure. The faces comprise a stacking of 20-50 planar graphene\nsheets with inter-sheet distance of ~ 0.340 nm. Average sizes of the particles\nand their flat faces are ~ 40 nm and ~ 15 nm, respectively. The astralen\nparticles are suggested to have defect-free sp^2 flat faces and all defects\ncondense at their polyhedral edges. Electron Paramagnetic Resonance (EPR)\nspectra of polycrystalline astralen samples reveal two components: a very broad\nsignal with DHpp > 1 T and an asymmetric narrow one centered close to g = 2.00.\nThe latter consists of two overlapping Lorentzian lines. All spectral\ncomponents are independent of ambient pressure. The intensities of all EPR\nsignals show no changes on decreasing temperature from T = 300 K down to 4 K\ndemonstrating the Pauli paramagnetism. Electron spin-lattice relaxation times\nT1e remain very short within the same temperature range. Temperature dependent\n13C Nuclear Magneti? Resonance (NMR) measurements yield nuclear spin-lattice\nrelaxation times T1n ~ T^-0.612. The exponent in the T1n(T)-dependence for\nastralen falls between the metallic behavior, T1n ~ T^-1 (Korringa relation),\nand the semiconductor behavior, T1n ~T^-0.5. All unusual magnetic resonance\nfeatures of astralen are attributed to delocalized charge carriers which amount\nconsiderably exceeds that of spins localized in defects on multi-shell\npolyhedra edges."
    },
    {
        "anchor": "Reversible hydrogenation and band gap opening of graphene and graphite\n  surfaces probed by scanning tunneling spectroscopy: The effect of hydrogenation on the topography and the electronic properties\nof graphene and graphite surfaces are studied by scanning tunneling microscopy\nand spectroscopy. The surfaces are chemically modified using Ar/H2 plasma.\nAnalyzing thousands of scanning tunneling spectroscopy measurements we\ndetermine that the hydrogen chemisorption on the surface of graphite/graphene\nopens on average an energy band gap of 0.4 eV around the Fermi level. We find\nthat although the plasma treatment modifies the surface topography in a\nnon-reversible way, the change in the electronic properties can be reversed by\na moderate thermal annealing and the samples can be hydrogenated again yielding\na similar, but slightly reduced, semiconducting behavior after the second\nhydrogenation.",
        "positive": "Contact gating at GHz frequency in graphene: The paradigm of graphene transistors is based on the gate modulation of the\nchannel carrier density by means of a local channel gate. This standard\narchitecture is subject to the scaling limit of the channel length and further\nrestrictions due to access and contact resistances impeding the device\nperformance. We propose a novel design, overcoming these issues by implementing\nadditional local gates underneath the contact region which allow a full control\nof the Klein barrier taking place at the contact edge. In particular, our work\ndemonstrates the GHz operation of transistors driven by independent contact\ngates. We benchmark the standard channel and novel contact gating and report\nfor the later dynamical transconductance levels at the state of the art. Our\nfinding may find applications in electronics and optoelectronics whenever there\nis need to control independently the Fermi level and the electrostatic\npotential of electronic sources or to get rid of cumbersome local channel\ngates."
    },
    {
        "anchor": "Emergence of Landauer Transport from Quantum Dynamics: A Model\n  Hamiltonian Approach: The Landauer expression for computing current-voltage characteristics in\nnanoscale devices is efficient and widely applicable but not suited to\ntransient phenomena and time dependent currents because it assumes that the\ncharge carrier population attains a time independent dynamic equilibrium as\nsoon as the external voltage is turned on. In this article, we construct a very\ngeneral expression for a time dependent current in an\nelectrode-molecule-electrode arrangement. Utilizing a model Hamiltonian, we\npropagate the Schrodinger wave function equation to numerically compute the\ntime dependent population in the individual sub-systems. The current in each\nelectrode (defined in terms of the rate of change of the corresponding\npopulation) has two components, one due to the charges originating from the\nsame electrode and the other due to the charges initially residing at the other\nelectrode. We derive an analytical expression for the first component and\nillustrate that it agrees reasonably with the numerical counterpart at early\ntimes. The structural form reveals that the initial occupancy can be factored\nout of the time dependent segment of the expression. We take this cue to\nconstruct a Landauer style formula and demonstrate that the current obtained\nfrom this simplified formula overlaps with our most general numerical current\nonly after the charge flow settles into a steady state. Thus, we illustrate the\nemergence of Landauer transport from a true first-principles quantum dynamics\ncalculation without any prior assumptions. Subsequently, we investigate the\ningredients in our model that regulate the onset time scale of this Landauer\nregime. We compare the performance of our general current expression with the\nLandauer current for time dependent electronic coupling. Finally, we comment on\nthe applicability of the Landauer formulas to compute hot-electron current\narising upon plasmon decoherence.",
        "positive": "Energy cooperation in quantum thermoelectric systems with multiple\n  electric currents: The energy efficiency and power of a quantum thermoelectric system with\nmultiple electric currents and only one heat currents are studied. The system\nis connected to the hot heat bath with one terminal but the cold bath with\nmultiple terminals or vice versal. We find that the cooperative effects can be\na potentially useful tool in improving the energy efficiency and output power\nin multi-terminal mesoscopic thermoelectric systems. As an example, we show\nthat the cooperation between the two thermoelectric effects in three-terminal\nthermoelectric systems leads to markedly improved performance of heat engine\nwithin the linear response regime using the Landauer-B\\\"{u}tiker formalism.\nSuch improvement also emerge in four-terminal thermoelectric heat engines with\nthree output electric currents. Cooperative effects in these multi-terminal\nthermoelectric systems can significantly enlarge the physical parameter region\nwith high efficiency and power. For refrigeration, we find that the energy\nefficiency can also be substantially improved if multi-terminal configurations\nare considered, suggesting a useful scheme toward electronic cooling. Our study\nillustrates cooperative effects as a convenient approach toward\nhigh-performance thermoelectric energy conversion in multi-terminal mesoscopic\nsystems."
    },
    {
        "anchor": "Electron correlation effects in a wide channel from the $\u03bd=1$ quantum\n  Hall edge states: The spatial behavior of Landau levels (LLs) for the $nu=1$ quantum Hall\nregime at the edge of a wide channel is studied in a self-consistent way by\nusing a generalized local density approximation proposed here. Both exchange\ninteraction and strong electron correlations, due to edge states, are taken\ninto account. They essentially modify the spatial behavior of the occupied\nlowest spin-up LL in comparison with that of the lowest spin-down LL, which is\ntotally empty. The contrast in the spatial behavior can be attributed to a\ndifferent effective one-electron lateral confining potentials for the\nspin-split LLs. Many-body effects on the spatially inhomogeneous spin-splitting\nare calculated within the screened Hartree-Fock approximation. It is shown\nthat, far from the edges, the maximum activation energy is dominated by the gap\nbetween the Fermi level and the bottom of the spin-down LL, because the gap\nbetween the Fermi level and the spin-up LL is much larger. In other words, the\nmaximum activation energy in the bulk of the channel corresponds to a highly\nasymmetric position of the Fermi level within the gap between spin-down and\nspin-up LLs in the bulk. We have also studied the renormalization of the\nedge-state group velocity due to electron correlations. The results of the\npresent theory are in line with those suggested and reported by experiments on\nhigh quality samples.",
        "positive": "Study of nonequilibrium Kondo phenomenon via nonperturbative dynamical\n  theory: We develop a nonperturbative dynamical theory (NDT) to calculate the retarded\nGreen's function under nonequilibrium conditions. The NDT is particularly\nuseful for treating nonequilibrium transport problems in systems with strong\ncorrelation. We apply our NDT to the well-known single-impurity Anderson model\nat equilibrium to determine its feasibility. We then apply it to a\nnonequilibrium transport problem in a system with Kondo coupling. An Anderson\nmodel with two metallic reservoirs is studied to understand the phenomenon of\nKondo-peak splitting in a single-electron transistor of mesoscopic size. We\ncalculate the nonequilibrium retarded Green's function by using the NDT and\nanalyze it in the atomic limit, where the novel coherent phenomenon manifested\nonly under nonequilibrium conditions can be described in an analytical manner.\nWe finally construct a self-consistent loop to calculate the retarded Green's\nfunction and present the results for spectral density and differential\nconductance obtained by the self-consistent method. Our results explain all the\nfeatures of Kondo-peak splitting observed in experiments. One remarkable\nconclusion is that Kondo-peak splitting is not the splitting of a conventional\nKondo peak, but the splitting of a novel coherent peak created under\nnonequilibrium steady-state conditions."
    },
    {
        "anchor": "Entangled Photon Pair Generation in Hybrid Superconductor-Semiconductor\n  Quantum Dot Devices: We investigate the effect of Cooper pair injection in shifting biexciton\nenergy level of low-symmetry (C2v) quantum dots (QDs) exhibiting nontrivial\nfine structure splitting. Coupling QDs to the superconducting coherent state\nforms extra fine structures by intermixing the ground and biexcitonic states\nwhere spectroscopic separation of neutral exciton and biexciton can be\ndiminished, yielding a system to be utilized in time reordering scheme. The\nseparability of exciton and biexciton energy levels is ascribed to the\ncorresponding direct, exchange and correlation energies calculated here through\nconfiguration interaction method. We demonstrate the possibility of enhancing\nphoton entanglement concurrence via providing an energy coincidence for\nbiexciton-exciton (XX \\rightarrow X) and exciton-ground (X \\rightarrow 0)\nemissions within the weak coupling regime.",
        "positive": "General response theory of topologically stable Fermi points and its\n  implications for disordered cases: We develop a general response theory of gapless Fermi points with nontrivial\ntopological charges for gauge and nonlinear sigma fields, which asserts that\nthe topological character of the Fermi points is embodied as the terms with\ndiscrete coefficients proportional to the corresponding topological charges.\nApplying the theory to the effective non-linear sigma models for topological\nFermi points with disorders in the framework of replica approach, we derive\nrigorously the Wess-Zumino terms with the topological charges being their\nlevels in the two complex symmetry classes of A and AIII. Intriguingly, two\nnontrivial examples of quadratic Fermi points with the topological charge `2'\nare respectively illustrated for the classes A and AIII. We also address a\nqualitative connection of topological charges of Fermi points in the real\nsymmetry classes to the topological terms in the non-linear sigma models, based\non the one-to-one classification correspondence."
    },
    {
        "anchor": "Observation of angle-dependent transmission of Dirac electrons in\n  graphene hetero junctions: The relativistic nature of charge carriers in graphene is expected to lead to\nan angle- dependent transmission through a potential barrier, where Klein\ntunneling involves annihilation of an electron and a hole at the edges of the\nbarrier. The signatures of Klein tunneling have been observed in gated graphene\ndevices, but the angle dependence of the transmission probability has not been\ndirectly observed. Here we show measurements of the angle-dependent\ntransmission through quasi-ballistic graphene heterojunctions with straight and\nangled leads, in which the barrier height is controlled by a shared gate\nelectrode. Using a balanced differential measurement technique, we isolate the\nangle-dependent contribution to the resistance from other angle-insensitive,\ngate-dependent and device-dependent effects. We find large oscillations in the\ntransmission as a function of the barrier height in the case of Klein tunneling\nat a 45 deg angle, as compared to normal incidence. Our results are consistent\nwith the model that predicts oscillations of the transmission probability due\nto interference of chiral carriers in a ballistic barrier. The observed angle\ndependence is the key element behind focusing of electrons and the realization\nof a Veselago lens in graphene.",
        "positive": "Berry phase effects in magnetism: Lecture notes published in ''Magnetism goes nano'', Lecture Manuscripts of\nthe 36th Spring School of the Institute of Solid State Research, edited by\nStefan Bluegel, Thomas Brueckel, and Claus M. Schneider (Forschungszentrum\nJuelich, 2005)."
    },
    {
        "anchor": "Tunable Anomalous Andreev Reflection and Triplet Pairings in Spin Orbit\n  Coupled Graphene: We theoretically study scattering process and superconducting triplet\ncorrelations in a graphene junction comprised of ferromagnet-RSO-superconductor\nin which RSO stands for a region with Rashba spin orbit interaction. Our\nresults reveal spin-polarized subgap transport through the system due to an\nanomalous equal-spin Andreev reflection in addition to conventional back\nscatterings. We calculate equal- and opposite-spin pair correlations near the\nF-RSO interface and demonstrate direct link of the anomalous Andreev reflection\nand equal-spin pairings arised due to the proximity effect in the presence of\nRSO interaction. Moreover, we show that the amplitude of anomalous Andreev\nreflection, and thus the triplet pairings, are experimentally controllable when\nincorporating the influences of both tunable strain and Fermi level in the\nnonsuperconducting region. Our findings can be confirmed by a conductance\nspectroscopy experiment and provide better insights into the proximity-induced\nRSO coupling in graphene layers reported in recent experiments.",
        "positive": "Magnetic edge states and magnetotransport in graphene antidot barriers: Magnetic fields are often used for characterizing transport in nanoscale\nmaterials. Recent magnetotransport experiments have demonstrated that ballistic\ntransport is possible in graphene antidot lattices (GALs). These experiments\nhave inspired the present theoretical study of GALs in a perpendicular magnetic\nfield. We calculate magnetotransport through graphene antidot barriers (GABs),\nwhich are finite rows of antidots arranged periodically in a pristine graphene\nsheet, using a tight-binding model and the Landauer-B\\\"uttiker formula. We show\nthat GABs behave as ideal Dirac mass barriers for antidots smaller than the\nmagnetic length, and demonstrate the presence of magnetic edge states, which\nare localized states on the periphery of the antidots due to successive\nreflections on the antidot edge in the presence of a magnetic field. We show\nthat these states are robust against variations in lattice configuration and\nantidot edge chirality. Moreover, we calculate the transmittance of disordered\nGABs and find that magnetic edge states survive a moderate degree of disorder.\nDue to the long phase-coherence length in graphene and the robustness of these\nstates, we expect magnetic edge states to be observable in experiments as well."
    },
    {
        "anchor": "Mechanism of Electron Spin Relaxation in Spiral Magnetic Structures: Spin dynamics in spiral magnetic structures has been investigated. It has\nbeen shown that the internal spatially dependent magnetic field in such\nstructures produces a new mechanism of spin relaxation.",
        "positive": "Manipulating chiral transmission by gate geometry: switching in graphene\n  with transmission gaps: We explore the chiral transmission of electrons across graphene\nheterojunctions for electronic switching using gate geometry alone. A sequence\nof gates is used to collimate and orthogonalize the chiral transmission lobes\nacross multiple junctions, resulting in negligible overall current. The\nresistance of the device is enhanced by several orders of magnitude by biasing\nthe gates into the bipolar $npn$ doping regime, as the ON state in the near\nhomogeneous $nn^-n$ regime remains highly conductive. The mobility is preserved\nbecause the switching involves a transmission gap instead of a structural\nband-gap that would reduce the number of available channels of conduction.\nUnder certain conditions this transmission gap is highly gate tunable, allowing\na subthermal turn-on that beats the Landauer bound on switching energy limiting\npresent day digital electronics."
    },
    {
        "anchor": "Exotic odd-even parity effects in transmission phase, (Andreev)\n  conductance, and shot noise of a dimer atomic chain by topology: We investigate the transport properties through a finite dimer chain\nconnected to two normal leads or one normal and one superconductor (SC) leads.\nThe dimer chain is described by the Su-Schrieffer-Hegger model and can be tuned\ninto a topologically nontrivial phase with a pair of zero-energy edge states\n(ZEESs). We find that if the dimer chain is of nontrivial topology, (1) it will\nshow apparent but opposite odd-even parity of the number of sites, in\ncomparison with the topologically trivial and plain chains, in the (Andreev)\ntransmission probability at the Fermi energy (i.e. the conductance and the\nAndreev conductance), the noise Fano factor in the zero bias limit, and even\nthe transmission phase due to the coupled ZEESs; (2) the ZEES can determine\nappearance of the Andreev bound states at the site connected to the SC lead,\nand thereby induces a nonzero-bias-anomaly in the Andreev differential\nconductance of the hybrid junction; (3) the transmission phase of the normal\njunction has a unique $2\\pi$ continuous phase variation at the zero-energy\nresonant peak that is also different from the usual phase shift in resonant\npoint in usual systems.",
        "positive": "$6\u03c0$ Josephson effect in Majorana box devices: We study Majorana devices featuring a competition between superconductivity\nand multi-channel Kondo physics. Our proposal extends previous work on\nsingle-channel Kondo systems to a topologically nontrivial setting of non-Fermi\nliquid type, where topological superconductor wires (with gap $\\Delta$)\nrepresent leads tunnel-coupled to a Coulomb-blockaded Majorana box. On the box,\na spin degree of freedom with Kondo temperature $T_K$ is nonlocally defined in\nterms of Majorana states. For $\\Delta\\gg T_K$, the destruction of Kondo\nscreening by superconductivity implies a $4\\pi$-periodic Josephson\ncurrent-phase relation. Using a strong-coupling analysis in the opposite regime\n$\\Delta \\ll T_K$, we find a $6\\pi$-periodic Josephson relation for three leads,\nwith critical current $I_c\\approx e\\Delta^2/ \\hbar T_K$, corresponding to the\ntransfer of fractionalized charges $e^*=2e/3$."
    },
    {
        "anchor": "Determination of Intrinsic Magnetic Response from Local Measurements of\n  Fringing Fields: Micron-sized Hall bars and micro-SQUIDs are now used routinely to measure the\nlocal static and dynamic magnetic response with micron-scale spatial\nresolution. While this provides a powerful new tool, determining the intrinsic\nmagnetization presents new challenges, as it requires correcting for\ndemagnetization fields that vary widely with position on a sample. In this\npaper we develop a method to correct for the demagnetization effect at local\npoints of a rectangular prism shaped sample using a finite element analysis of\nMaxwell's equation applied to local Hall sensor measurements calibrated by bulk\nmeasurements of the magnetization. This method can be generalized to other\ngeometric shapes to analyze data obtained with local magnetic probes.",
        "positive": "First-Principles Calculation of Thermal Transport in the Metal/Graphene\n  System: Thermal properties in the metal/graphene (Gr) systems are analyzed by using\nan atomistic phonon transport model based on Landauer formalism and\nfirst-principles calculations. The specific structures under investigation\ninclude chemisorbed Ni(111)/Gr, physisorbed Cu(111)/Gr and Au(111)/Gr, as well\nas Pd(111)/Gr with intermediate characteristics. Calculated results illustrate\na strong dependence of thermal transfer on the details of interfacial\nmicrostructures. In particular, it is shown that the chemisorbed case provides\na generally smaller interfacial thermal resistance than the physisorbed due to\nthe stronger bonding. However, our calculation also indicates that the weakly\nchemisorbed interface of Pd/Gr may be an exception, with the largest thermal\nresistance among the considered. Further examination of the electrostatic\npotential and interatomic force constants reveal that the mixed bonding force\nbetween the Pd and C atoms results in incomplete hybridization of Pd and\ngraphene orbital states at the junction, leading effectively to two phonon\ninterfaces and a larger than expected thermal resistance. Comparison with\navailable experimental data shows good agreement. The result clearly suggests\nthe feasibility of phonon engineering for thermal property optimization at the\ninterface."
    },
    {
        "anchor": "Hexagonal warping on optical conductivity of surface states in\n  Topological Insulator Bi_{2}Te_{3}: ARPES studies of the protected surface states in the Topological Insulator $%\nBi_{2}Te_{3}$ have revealed the existence of an important hexagonal warping\nterm in its electronic band structure. This term distorts the shape of the\nDirac cone from a circle at low energies to a snowflake shape at higher\nenergies. We show that this implies important modifications of the interband\noptical transitions which no longer provide a constant universal background as\nseen in graphene. Rather the conductivity shows a quasilinear increase with a\nslightly concave upward bending as energy is increased. Its slope increases\nwith increasing magnitude of the hexagonal distortion as does the magnitude of\nthe jump at the interband onset. The energy dependence of the density of states\nis also modified and deviates downward from linear with increasing energy.",
        "positive": "Critical conductance of two-dimensional chiral systems with random\n  magnetic flux: The zero temperature transport properties of two-dimensional lattice systems\nwith static random magnetic flux per plaquette and zero mean are investigated\nnumerically. We study the two-terminal conductance and its dependence on\nenergy, sample size, and magnetic flux strength. The influence of boundary\nconditions and of the oddness of the number of sites in the transverse\ndirection is also studied. We confirm the existence of a critical chiral state\nin the middle of the energy band and calculate the critical exponent nu=0.35\n+/- 0.03 for the divergence of the localization length. The sample averaged\nscale independent critical conductance <g>_c turns out to be a function of the\namplitude of the flux fluctuations whereas the variance of the respective\nconductance distributions appears to be universal. All electronic states\noutside of the band center are found to be localized."
    },
    {
        "anchor": "Metastable solitonic states in the strained itinerant helimagnet FeGe: The tensile strain is a promising tool for creation and manipulation of\nmagnetic solitonic textures in the chiral helimagnets via tunable control of\nmagnetic anisotropy and Dzyaloshinskii-Moriya interaction. Here, by using the\nin-situ resonant small-angle x-ray scattering we demonstrate that the skyrmion\nand chiral soliton lattices can be achieved as metastable states in FeGe\nlamella as distinct states or even simultaneously by combining the tensile\nstrain and magnetic fields in various orientations with respect to the\ndeformation. The small-angle scattering data are discussed in the frame of the\nanalytical model which is sufficient to describe the experimental results for\nsoliton lattice. By using the experimental results and analytical theory,\nunwinding of the metastable skyrmions in the perpendicular magnetic field as\nseen by small-angle scattering experiment was analyzed by the micromagnetic\nsimulation.",
        "positive": "Fano Resonances in Majorana Bound States - Quantum Dot Hybrid Systems: We consider a quantum wire, containing two Majorana bound states (MBS) at its\nends that are coupled to a current lead on one side and to a quantum dot (QD)\non the other side. Using the method of full counting statistics we calculate\nthe conductance and the zero-frequency noise. Using an effective low-energy\nmodel, we analyze in detail the Andreev reflection probability as a function of\nthe various system parameters and show that it exhibits a Fano resonance (FR)\nline shape in the case of a weakly coupled QD as a function of the QD energy\nlevel when the two MBS overlap. The asymmetry parameter changes sign as the\nbias voltage is tuned through the MBS overlap energy. The FR is mirrored as a\nfunction of the QD level energy as long as tunneling to the more distant MBS is\nnegligible. However, if both MBS are coupled to the lead and the QD, the height\nas well as the asymmetry of the line shapes cease to respect this symmetry.\nThese two exclusive cases uniquely distinguish the coupling to a MBS from the\ncoupling to a fermionic bound state that is shared between the two MBS. We\ncomplement the analysis by employing a discretized one-dimensional p-wave\nsuperconductor (Kitaev chain) for the quantum wire and show that the features\nof the effective low-energy model are robust towards a more complete\nHamiltonian and also persist at finite temperature."
    },
    {
        "anchor": "Self-hybridisation between interband transitions and Mie modes in\n  dielectric nanoparticles: We discuss the possibility of self-hybridisation in high-index dielectric\nnanoparticles, where Mie modes of electric or magnetic type can couple to the\ninterband transitions of the material, leading to spectral anticrossings.\nStarting with an idealised system described by moderately high constant\npermittivity with a narrow Lorentzian, in which self-hybridisation is visible\nfor both plane-wave and electron-beam excitation, we embark on a quest for\nrealistic systems where this effect should be visible. We explore a variety of\nspherical particles made of traditional semiconductors such as Si, GaAs, and\nGaP. With the effect hardly discernible, we identify two major causes hindering\nobservation of self-hybridisation: the very broad spectral fingerprints of\ninterband transitions in most candidate materials, and the significant overlap\nbetween electric and magnetic Mie modes in nanospheres. We thus depart from the\nspherical shape, and show that interband--Mie hybridisation is indeed feasible\nin the example of GaAs cylinders, even with a simple plane-wave source. This\nso-far unreported kind of polariton has to be considered when interpreting\nexperimental spectra of Mie-resonant nanoparticles and assigning modal\ncharacters to specific features. On the other hand, it has the potential to be\nuseful for the characterisation of the optical properties of dielectric\nmaterials, through control of the hybridisation strength via nanoparticle size\nand shape.",
        "positive": "Semiclassical study of edge states and transverse electron focusing for\n  strong spin-orbit coupling: We studied the edge states and transverse electron focusing in the presence\nof spin-orbit interaction in a two dimensional electron gas. Assuming strong\nspin-orbit coupling we derived semiclassical quantization conditions to\ndescribe the dispersion of the edge states. Using the dispersion relation we\nthen make predictions about certain properties of the focusing spectrum.\nComparison of our analytical results with quantum mechanical transport\ncalculations reveals that certain features of the focusing spectrum can be\nquite well understood in terms of the interference of the edge states while the\nexplanation of other features seems to require a different approach."
    },
    {
        "anchor": "Suggested design of gold-nanoobjects-based terahertz radiation source\n  for biomedical research: Gold nanoparticles (GNPs) may serve as \"devices\" to emit electromagnetic\nradiation in the terahertz (THz) range, whereby the energy is delivered by\nradio frequency or microwave photons which won't by themselves induce\ntransitions between sparse confinement-shaped electron levels of a GNP, but may\nborrow the energy from longitudinal acoustic phonons to overcome the\nconfinement gap. Upon excitation, the Fermi electron cannot relax otherwise\nthan via emitting a THz photon, the other relaxation channels being blocked by\nforce of shape and size considerations. Within this general scope that has been\nalready outlined earlier, the present work specifically discusses two-phonon\nprocesses, namely (i) a combined absorption-emission of two phonons from the\ntop of the longitudinal acoustic branch, and (ii) an absorption of two such\nphonons with nearly identical wavevectors. The case (i) may serve as a source\nof \"soft\" THz radiation (at ~0.54 THz), the case (ii) the \"hard\" THz radiation\nat 8.7 THz. Numerical estimates are done for crystalline particles in the shape\nof rhombicuboctahedra, of 5 - 7 nm \"diameter\". A technical realisation of this\nidea is briefly discussed, assuming the deposition of GNPs onto / within the\nsubstrate of Teflon, the material sustaining high temperatures and transparent\nin the THz range.",
        "positive": "Spin Hall Insulator: Recent theories predict dissipationless spin current induced by an electric\nfield in doped semiconductors. Nevertheless, the charge current is still\ndissipative in these systems. In this work, we theoretically predict the\ndissipationless spin Hall effect, without any accompanying charge current, in\nsome classes of band insulators, including zero-gap semiconductors such as HgTe\nand narrow-gap semiconductors such as PbTe. This effect is similar to the\nquantum Hall effect in that all the states below the gap contribute and there\noccurs no dissipation. However the spin Hall conductance is not quantized even\nin two dimensions. This is the first example of a nontrivial topological\nstructure in a band insulator without any magnetic field."
    },
    {
        "anchor": "Magnetic field-induced Kondo effects in Coulomb blockade systems: We review the peculiarities of transport through a quantum dot caused by the\nspin transition in its ground state. Such transitions can be induced by a\nmagnetic field. Tunneling of electrons between the dot and leads mixes the\nstates belonging to the ground state manifold of the dot. Unlike the\nconventional Kondo effect, this mixing, which occurs only at the\nsinglet-triplet transition point, involves both the orbital and spin degrees of\nfreedom of the electrons. We present theoretical and experimental results that\ndemonstrate the enhancement of the conductance through the dot at the\ntransition point.",
        "positive": "Mechanically Induced Thermal Breakdown in Magnetic Shuttle Structures: A theory of a thermally induced single-electron \"shuttling\" instability in a\nmagnetic nanomechanical device subject to an external magnetic field is\npresented in the Coulomb blockade regime of electron transport. The model\nmagnetic shuttle device considered comprises a movable metallic grain suspended\nbetween two magnetic leads, which are kept at different temperatures and\nassumed to be fully spin polarized with antiparallel magnetizations. For a\ngiven temperature difference shuttling is found to occur for a region of\nexternal magnetic fields between a lower and an upper critical field strength,\nwhich separate the shuttling regime from normal small-amplitude \"vibronic\"\nregimes. We find that (i) the upper critical magnetic field saturates to a\nconstant value in the high temperature limit and that the shuttle instability\ndomain expands with a decrease of the temperature, (ii) the lower critical\nmagnetic field depends not only on the temperature independent phenomenological\nfriction coefficient used in the model but also on intrinsic friction (which\nvanishes in the high temperature limit) caused by magnetic exchange forces and\nelectron tunneling between the quantum dot and the leads. The feasibility of\nusing thermally driven magnetic shuttle systems to harvest thermal breakdown\nphenomena is discussed."
    },
    {
        "anchor": "Nonlinear theory of fractional microwave-induced magnetoresistance\n  oscillations in a dc-driven two-dimensional electron system: Microwave-induced nonlinear magnetoresistance in a dc-driven two-dimensional\nelectron system is examined using a multi-photon-assisted transport scheme\ndirect controlled by the current. It is shown that near the 2nd subharmonic of\nthe cyclotron resonance, the frequency of the resistivity oscillation with the\nmagnetic-field-normalized current-density is double that at the cyclotron\nresonance and its harmonics, in excellent agreement with recent experimental\nfindings by Hatke {\\it et al.} [Phys. Rev. Lett. {\\bf 101}, 246811 (2008)]. The\ncurrent-induced alternative emergence of resonant two-photon and single-photon\nprocesses is responsible for this frequency doubling. Near the third\nsubharmonic of the cyclotron resonance, the current-induced consecutive\nappearance of resonant 0-/3-photon, two-photon, and single-photon processes may\nlead to the frequency tripling of the resistivity oscillation.",
        "positive": "Transient behavior of heat transport in a thermal switch: We study the time-dependent transport of heat in a nanoscale thermal switch.\nThe switch consists of left and right leads that are initially uncoupled.\nDuring switch-on the coupling between the leads is abruptly turned on. We use\nthe nonequilibrium Green's function formalism and numerically solve the\nconstructed Dyson equation to determine the nonperturbative heat current. At\nthe transient regime we find that the current initially flows simultaneously\ninto both of the leads and then afterwards oscillates between flowing into and\nout of the leads. At later times the oscillations decay away and the current\nsettles into flowing from the hotter to the colder lead. We find the transient\nbehavior to be influenced by the extra energy added during switch-on. Such a\ntransient behavior also exists even when there is no temperature difference\nbetween the leads. The current at the long-time limit approaches the\nsteady-state value independently calculated from the Landauer formula."
    },
    {
        "anchor": "Interlayer Interactions and the Fermi Energy of Bilayer Composite\n  Fermion Metals: When two 2D electron gas layers, each at Landau level filling factor\n$\\nu=1/2$, are close together a condensate of interlayer excitons emerges at\nlow temperature. Although the excitonic phase is qualitatively well understood,\nthe incoherent phase just above the critical layer separation is not. Using a\ncombination of interlayer tunneling spectroscopy and conventional transport, we\nexplore the incoherent phase in samples both near the phase boundary and\nfurther from it. In the more closely spaced bilayers we find the electronic\nspectral functions narrower and the Fermi energy of the $\\nu = 1/2$ composite\nfermion metal smaller than in the more widely separated bilayers. We attribute\nthese effects to a softening of the intralayer Coulomb interaction due to\ninterlayer screening.",
        "positive": "Topological defects in flat nanomagnets: the magnetostatic limit: We discuss elementary topological defects in soft magnetic nanoparticles in\nthe thin-film geometry. In the limit dominated by magnetostatic forces the\nlow-energy defects are vortices (winding number n = +1), cross ties (n = -1),\nand edge defects with n = -1/2. We obtain topological constraints on the\npossible composition of domain walls. The simplest domain wall in this regime\nis composed of two -1/2 edge defects and a vortex, in accordance with\nobservations and numerics."
    },
    {
        "anchor": "Surface effects on the statistics of the local density of states in\n  metallic nanoparticles: manifestation on the NMR spectra: In metallic nanoparticles, shifts in the ionization energy of surface atoms\nwith respect to bulk atoms can lead to surface bands. Within a simple Tight\nBinding model we find that the projection of the electronic density of states\non these sites presents two overlapping structures. One of them is\ncharacterized by the level spacing coming from bulk states and the other arises\nfrom the surface states. In very small particles, this contributes to an\nover-broadening of the NMR absorption spectra, determined by the Knight shift\ndistribution of magnetic nuclei. We compare our calculated Knight shifts with\nexperiments on aluminum nanoparticles, and show that the deviation of the\nscaling law as a function of temperature and particle size can be explained in\nterms of surface states.",
        "positive": "Interlayer Exciton Optoelectronics in a 2D Heterostructure p-n Junction: Semiconductor heterostructures are backbones for solid state based\noptoelectronic devices. Recent advances in assembly techniques for van der\nWaals heterostructures has enabled the band engineering of semiconductor\nheterojunctions for atomically thin optoelectronic devices. In two-dimensional\nheterostructures with type II band alignment, interlayer excitons, where\nCoulomb-bound electrons and holes are confined to opposite layers, have shown\npromising properties for novel excitonic devices, including a large binding\nenergy, micron-scale in-plane drift-diffusion, and long population and valley\npolarization lifetime. Here, we demonstrate interlayer exciton optoelectronics\nbased on electrostatically defined lateral p-n junctions in a MoSe2-WSe2\nheterobilayer. Applying a forward bias enables the first observation of\nelectroluminescence from interlayer excitons. At zero bias, the p-n junction\nfunctions as a highly sensitive photodetector, where the wavelength-dependent\nphotocurrent measurement allows the direct observation of resonant optical\nexcitation of the interlayer exciton. The resulting photocurrent amplitude from\nthe interlayer exciton is about 200 times smaller compared to the resonant\nexcitation of intralayer exciton. This implies that the interlayer exciton\noscillator strength is two orders of magnitude smaller than that of the\nintralayer exciton due to the spatial separation of electron and hole to\nopposite layers. These results lay the foundation for exploiting the interlayer\nexciton in future 2D heterostructure optoelectronic devices."
    },
    {
        "anchor": "Experimental determination of the energy per particle in partially\n  filled Landau levels: We describe an experimental technique to measure the chemical potential,\n$\\mu$, in atomically thin layered materials with high sensitivity and in the\nstatic limit. We apply the technique to a high quality graphene monolayer to\nmap out the evolution of $\\mu$ with carrier density throughout the N=0 and N=1\nLandau levels at high magnetic field. By integrating $\\mu$ over filling factor,\n$\\nu$, we obtain the ground state energy per particle, which can be directly\ncompared with numerical calculations. In the N=0 Landau level, our data show\nexceptional agreement with numerical calculations over the whole Landau level\nwithout adjustable parameters, as long as the screening of the Coulomb\ninteraction by the filled Landau levels is accounted for. In the N=1 Landau\nlevel, comparison between experimental and numerical data reveals the\nimportance of valley anisotropic interactions and the presence of\nvalley-textured electron solids near odd filling.",
        "positive": "Hopping Transport in Granular Superconductors: We study the conductivity of granular superconductors in the weak coupling\ninsulating regime. We show that it is governed by the hopping of either\nelectrons or Cooper pairs depending on the relation between the superconducting\ngap and the charging energy of a single granule. Local superconducting pairing\nplays an important role in both cases. In particular, in the case of the\ntransport via electron hopping the superconducting gap suppresses the inelastic\ncotunneling processes. We determine transport characteristics of an array in\ndifferent regimes and construct the transport phase diagram."
    },
    {
        "anchor": "Amplification and spectral evidence of squeezing in the response of a\n  strongly driven nanoresonator to a probe field: Because of their small decay rates, nanomechanical modes enable studying\nstrongly nonlinear phenomena for a moderately strong resonant driving. Here we\nstudy the response of a driven resonator to an additional probe field. We\nexperimentally demonstrate resonant amplification and resonant absorption of\nthe probe field. The corresponding spectral peaks lie on the opposite sides of\nthe strong-drive frequency. Even though the fluctuation-dissipation theorem\ndoes not apply, we show that the response to the probe field allows us to\ncharacterize the squeezing of fluctuations about the stable states of forced\noscillations. Our two-tone experiment is done in the classical regime, but our\nfindings should equally apply to quantum fluctuations as well. In quantum\nterms, the observed response is due to multiphoton processes. The squeezing\nparameter extracted from the spectra of the response is in excellent agreement\nwith the calculated value with no free parameters.",
        "positive": "Inelatic cotunneling current and shot noise of an interacting quantum\n  dot with ferromagnetic correlations: We explore inelastic cotunneling through a strongly Coulomb-blockaded quantum\ndot attached to two ferromagnetic leads in the weak coupling limit using a\ngeneric quantum Langevin equation approach. We first develop a Bloch-type\nequation microscopically to describe the cotunneling-induced spin relaxation\ndynamics, and then develop explicit analytical expressions for the local\nmagnetization, current, and its fluctuations. On this basis, we predict a novel\nzero-bias anomaly of the differential conductance in the absence of a magnetic\nfield for the anti-parallel configuration, and asymmetric peak splitting in a\nmagnetic field. Also, for the same system with large polarization, we find a\nnegative zero-frequency differential shot noise in the low positive\nbias-voltage region. All these effects are ascribed to rapid spin-reversal due\nto underlying spin-flip cotunneling."
    },
    {
        "anchor": "The Faraday effect revisited: General theory: This paper is the first in a series revisiting the Faraday effect, or more\ngenerally, the theory of electronic quantum transport/optical response in bulk\nmedia in the presence of a constant magnetic field. The independent electron\napproximation is assumed. At zero temperature and zero frequency, if the Fermi\nenergy lies in a spectral gap, we rigorously prove the Widom-Streda formula.\nFor free electrons, the transverse conductivity can be explicitly computed and\ncoincides with the classical result. In the general case, using magnetic\nperturbation theory, the conductivity tensor is expanded in powers of the\nstrength of the magnetic field $B$. Then the linear term in $B$ of this\nexpansion is written down in terms of the zero magnetic field Green function\nand the zero field current operator. In the periodic case, the linear term in\n$B$ of the conductivity tensor is expressed in terms of zero magnetic field\nBloch functions and energies. No derivatives with respect to the quasi-momentum\nappear and thereby all ambiguities are removed, in contrast to earlier work.",
        "positive": "Topological data analysis and machine learning: Topological data analysis refers to approaches for systematically and\nreliably computing abstract ``shapes'' of complex data sets. There are various\napplications of topological data analysis in life and data sciences, with\ngrowing interest among physicists. We present a concise yet (we hope)\ncomprehensive review of applications of topological data analysis to physics\nand machine learning problems in physics including the detection of phase\ntransitions. We finish with a preview of anticipated directions for future\nresearch."
    },
    {
        "anchor": "Global phase diagram of charge neutral graphene in the quantum Hall\n  regime for generic interactions: Monolayer graphene at charge neutrality in a quantizing magnetic field is a\nquantum Hall ferromagnet. Due to the spin and valley (near) degeneracies, there\nis a plethora of possible ground states. Previous theoretical work, based on a\nstringent ultra short-range assumption on the symmetry-allowed interactions,\npredicts a phase diagram with distinct regions of spin-polarized, canted\nantiferromagnetic, inter-valley coherent, and charge density wave order. While\nearly experiments suggested that the system was in the canted antiferromagnetic\nphase at a perpendicular field, recent scanning tunneling studies universally\nfind Kekul\\'e bond order, and sometimes also charge density wave order.\nRecently, it was found that if one relaxes the stringent assumption mentioned\nabove, a phase with coexisting canted antiferromagnetic and Kekul\\'e order\nexists in the region of the phase diagram believed to correspond to real\nsamples. In this work, starting from the continuum limit appropriate for\nexperiments, we present the complete phase diagram of $\\nu=0$ graphene in the\nHartree-Fock approximation, using generic symmetry-allowed interactions,\nassuming translation invariant ground states up to an intervalley coherence.\nAllowing for a sublattice potential (valley Zeeman coupling), we find numerous\nphases with different types of coexisting order. We conclude with a discussion\nof the physical signatures of the various states.",
        "positive": "Tuning the Spin Hall Effect in a Two-Dimensional Electron Gas: We provide a theoretical framework for the electric field control of the\nelectron spin in systems with diffusive electron motion. The approach is valid\nin the experimentally important case where both intrinsic and extrinsic\nspin-orbit interaction in a two-dimensional electron gas are present\nsimultaneously. Surprisingly, even when the extrinsic mechanism is the dominant\ndriving force for spin Hall currents, the amplitude of the spin Hall\nconductivity may be considerably tuned by varying the intrinsic spin-orbit\ncoupling via a gate voltage. Furthermore we provide an explanation of the\nexperimentally observed out-of-plane spin polarization in a (110) GaAs quantum\nwell."
    },
    {
        "anchor": "Quantized Anomalous Hall Effect in Two-Dimensional Ferromagnets -\n  Quantum Hall Effect from Metal -: We study the effect of disorder on the anomalous Hall effect (AHE) in\ntwo-dimensional ferromagnets. The topological nature of AHE leads to the\ninteger quantum Hall effect from a metal, i.e., the quantization of\n$\\sigma_{xy}$ induced by the localization except for the few extended states\ncarrying Chern number. Extensive numerical study on a model reveals that\nPruisken's two-parameter scaling theory holds even when the system has no gap\nwith the overlapping multibands and without the uniform magnetic field.\nTherefore the condition for the quantized AHE is given only by the Hall\nconductivity $\\sigma_{xy}$ without the quantum correction, i.e., $|\\sigma_{xy}|\n> e^2/(2h)$.",
        "positive": "Quantum mold casting for topological insulating and edge states: We study the possibility of transferring fermions from a trivial system as\nparticle source to an empty system but at topological phase as a mold for\ncasting a stable topological insulator dynamically. We show that this can be\nrealized by a non-Hermitian unidirectional hopping, which connects a central\nsystem at topological phase and a trivial flat-band system with a periodic\ndriving chemical potential, which scans over the valence band of the central\nsystem. The near exceptional-point dynamics allows a unidirectional dynamical\nprocess: the time evolution from an initial state with full-filled source\nsystem to a stable topological insulating state approximately. The result is\ndemonstrated numerically by a source-assistant QWZ model and SSH chain in the\npresence of random perturbation. Our finding reveals a classical analogy of\nquench dynamics in quantum matter and provides a way for topological quantum\nstate engineering."
    },
    {
        "anchor": "Nonclassical statistics from a polaritonic Josephson junction: We theoretically study the emission statistics of a weakly nonlinear photonic\ndimer during coherent oscillations. We show that the phase and population\ndynamics allow to periodically meet an optimal intensity squeezing condition\nresulting in a strongly nonclassical emission statistics. By considering an\nexciton-polariton Josephson junction resonantly driven by a classical source,\nwe show that a sizeable antibunching should emerge in such semiconductor system\nwhere intrinsic nonclassical signatures have remained elusive to date.",
        "positive": "Higher-order mesoscopic fluctuations in quantum wires: Conductance and\n  current cumulants: We study conductance cumulants $<< g^n >>$ and current cumulants $C_j$\nrelated to heat and electrical transport in coherent mesoscopic quantum wires\nnear the diffusive regime. We consider the asymptotic behavior in the limit\nwhere the number of channels and the length of the wire in the units of the\nmean free path are large but the bare conductance is fixed. A recursion\nequation unifying the descriptions of the standard and Bogoliubov--de Gennes\n(BdG) symmetry classes is presented. We give values and come up with a novel\nscaling form for the higher-order conductance cumulants. In the BdG wires, in\nthe presence of time-reversal symmetry, for the cumulants higher than the\nsecond it is found that there may be only contributions which depend\nnonanalytically on the wire length. This indicates that diagrammatic or\nsemiclassical pictures do not adequately describe higher-order spectral\ncorrelations. Moreover, we obtain the weak-localization corrections to $C_j$\nwith $j\\le 10$."
    },
    {
        "anchor": "Competition of trivial and topological phases in patterned graphene\n  based heterostructures: We explore the effect of mechanical strain on the electronic spectrum of\npatterned graphene based heterostructures. We focus on the competition of\nKekul\\'e-O type distortion favoring a trivial phase and commensurate Kane-Mele\ntype spin-orbit coupling generating a topological phase. We derive a simple\nlow-energy Dirac Hamiltonian incorporating the two gap promoting mechanisms and\ninclude terms corresponding to uniaxial strain. The derived effective model\nexplains previous ab initio results through a simple physical picture. We show\nthat while the trivial gap is sensitive to mechanical distortions, the\ntopological gap stays resilient.",
        "positive": "Bichromatic four-wave mixing and quadrature-squeezing from biexcitons in\n  atomically thin semiconductor microcavities: Nonlinear optical effects such as four-wave mixing and generation of squeezed\nlight are ubiquitous in optical devices and light sources. For new devices\noperating at low optical power, the resonant nonlinearity arising from the\ntwo-photon sensitive bound biexciton in a semiconductor microcavity is an\ninteresting prospective platform. Due to the particularly strong Coulomb\ninteraction in atomically thin semiconductors, these materials have strongly\nbound biexcitons and operate in the visible frequency range of the\nelectromagnetic spectrum. To remove the strong pump laser from the generated\nlight in optical devices or to simultaneously excite non-degenerate polaritons,\na bichromatic-pump configuration with two spectrally separated pump lasers is\ndesirable. In this paper, we theoretically investigate spontanous four-wave\nmixing and quadrature-squeezing in a bichromatically pumped atomically thin\nsemiconductor microcavity. We explore two different configurations that support\ndegenerate and non-degenerate scattering from polaritons into bound biexcitons,\nrespectively. We find that these configurations lead to the generation strongly\nsingle- and two-mode quadrature-squeezed light."
    },
    {
        "anchor": "Chiral Topological Semimetal with Multifold Band Crossings and Long\n  Fermi arcs: Topological semimetals in crystals with a chiral structure (which possess a\nhandedness due to a lack of mirror and inversion symmetries) are expected to\ndisplay numerous exotic physical phenomena, including fermionic excitations\nwith large topological charge [1], long Fermi arc surface states [2,3], unusual\nmagnetotransport [4] and lattice dynamics [5], as well as a quantized response\nto circularly polarized light [6]. To date, all experimentally confirmed\ntopological semimetals exist in crystals that contain mirror operations,\nmeaning that these properties do not appear. Here, we show that AlPt is a\nstructurally chiral topological semimetal that hosts new fourfold and sixfold\nfermions, which can be viewed as a higher spin eneralization of Weyl fermions\nwithout equivalence in elementary particle physics. These multifold fermions\nare located at high symmetry points and have Chern numbers larger than those in\nWeyl semimetals, thus resulting in multiple Fermi arcs that span the full\ndiagonal of the surface Brillouin zone. By imaging these long Fermi arcs, we\nexperimentally determine the magnitude and sign of their Chern number, allowing\nus to relate their dispersion to the handedness of their host crystal.",
        "positive": "Spin Polarization Phenomena and Pseudospin Quantum Hall Ferromagnetism\n  in the HgTe Quantum Well: The parallel field of a full spin polarization of the electron gas in a\n\\Gamma8 conduction band of the HgTe quantum well was obtained from the\nmagnetoresistance by three different ways in a zero and quasi-classical range\nof perpendicular field component Bper. In the quantum Hall range of Bper the\nspin polarization manifests in anticrossings of magnetic levels, which were\nfound to strongly nonmonotonously depend on Bper."
    },
    {
        "anchor": "Electrically Tunable Four-Wave-Mixing in Graphene Heterogeneous Fiber\n  for Individual Gas Molecule Detection: Detection of individual molecules is the ultimate goal of any chemical\nsensor. In the case of gas detection, such resolution has been achieved in\nadvanced nanoscale electronic solid-state sensors, but it has not been possible\nso far in integrated photonic devices, where the weak light-molecule\ninteraction is typically hidden by noise. Here, we demonstrate a scheme to\ngenerate ultrasensitive down-conversion four-wave-mixing (FWM) in a graphene\nbipolar-junction-transistor heterogeneous D-shaped fiber. In the communication\nband, the FWM conversion efficiency can change steeply when the graphene Fermi\nlevel approaches 0.4 eV. In this condition, we exploit our unique two-step\noptoelectronic heterodyne detection scheme, and we achieve real-time individual\ngas molecule detection in vacuum. Such combination of graphene strong\nnonlinearities, electrical tunability, and all-fiber integration paves the way\ntoward the design of versatile high-performance graphene photonic devices.",
        "positive": "Signatures of Majorana Fermions in Topological Insulator Josephson\n  Junction Devices: We study theoretically the electrical current and low-frequency noise for a\nlinear Josephson junction structure on a topological insulator, in which the\nsuperconductor forms a closed ring and currents are injected from normal\nregions inside and outside the ring. We find that this geometry offers a\nsignature for the presence of gapless 1D Majorana fermion modes that are\npredicted in the channel when the phase difference \\phi, controlled by the\nmagnetic flux through the ring, is \\pi. We show that for low temperature the\nlinear conductance jumps when \\phi\\ passes through \\pi, accompanied by\nnon-local correlations between the currents from the inside and outside of the\nring. We compute the dependence of these features on temperature, voltage and\nlinear dimensions, and discuss the implications for experiments."
    },
    {
        "anchor": "Scaling in activated escape of underdamped systems: Noise-induced escape from a metastable state of a dynamical system is studied\nclose to a saddle-node bifurcation point, but in the region where the system\nremains underdamped. The activation energy of escape scales as a power of the\ndistance to the bifurcation point. We find two types of scaling and the\ncorresponding critical exponents.",
        "positive": "Magnetization oscillations by vortex-antivortex dipoles: A vortex-antivortex dipole can be generated due to current with in-plane\nspin-polarization, flowing into a magnetic element, which then behaves as a\nspin transfer oscillator. Its dynamics is analyzed using the Landau-Lifshitz\nequation including a Slonczewski spin-torque term. We establish that the vortex\ndipole is set in steady state rotational motion due to the interaction between\nthe vortices, while an external in-plane magnetic field can tune the frequency\nof rotation. The rotational motion is linked to the nonzero skyrmion number of\nthe dipole. The spin-torque acts to stabilize the vortex dipole at a definite\nvortex-antivortex separation distance. In contrast to a free vortex dipole, the\nrotating pair under spin-polarized current is an attractor of the motion,\ntherefore a stable state. Three types of vortex-antivortex pairs are obtained\nas we vary the external field and spin-torque strength. We give a guide for the\nfrequency of rotation based on analytical relations."
    },
    {
        "anchor": "Strong nonreciprocity in modulated resonator chains through synthetic\n  electric and magnetic fields: We study nonreciprocity in spatiotemporally modulated 1D resonator chains\nfrom the perspective of equivalent 2D resonator arrays with a synthetic\ndimension and transverse synthetic electric and magnetic fields. The synthetic\nfields are respectively related to temporal and spatial modulation of the\nresonator chain, and we show that their combination can break transmission\nreciprocity without additional elements. This nonreciprocal effect is analogous\nto the Hall effect for charged particles. We experimentally implement chains of\n2 and 3 spatiotemporally modulated resonators and measure over 58 dB of\nisolation contrast.",
        "positive": "Skyrmions at the edge: Confinement effects in Fe/Ir(111): We have employed spin-polarized scanning tunneling microscopy and Monte-Carlo\nsimulations to investigate the effect of lateral confinement onto the\nnanoskyrmion lattice in Fe/Ir(111). We find a strong coupling of one diagonal\nof the square magnetic unit cell to the close-packed edges of Fe\nnanostructures. In triangular islands this coupling in combination with the\nmismatching symmetries of the islands and of the square nanoskyrmion lattice\nleads to frustration and triple-domain states. In direct vicinity to\nferromagnetic NiFe islands, the surrounding skyrmion lattice forms additional\ndomains. In this case a side of the square magnetic unit cell prefers a\nparallel orientation to the ferromagnetic edge. These experimental findings can\nbe reproduced and explained by Monte-Carlo simulations. Here, the single-domain\nstate of a triangular island is lower in energy, but nevertheless multi-domain\nstates occur due to the combined effect of entropy and an intrinsic domain wall\npinning arising from the skyrmionic character of the spin texture."
    },
    {
        "anchor": "Electromagnetic eigenmodes in matter. van der Waals-London and Casimir\n  forces: We derive van der Waals-London and Casimir forces by calculating the\neigenmodes of the electromagnetic field interacting with two semi-infinite\nbodies (two halves of space) with parallel surfaces separated by distance d. We\nadopt simple models for metals and dielectrics, well-known in the elementary\ntheory of dispersion. In the non-retarded (Coulomb) limit we get a d^{-3}-force\n(van der Waals-London force), arising from the zero-point energy (vacuum\nfluctuations) of the surface plasmon modes. When retardation is included we\nobtain a d^{-4}-(Casimir) force, arising from the zero-point energy of the\nsurface plasmon-polariton modes (evanescent modes) for metals, and from\npropagating (polaritonic) modes for identical dielectrics. The same Casimir\nforce is also obtained for \"fixed surfaces\" boundary conditions, irrespective\nof the pair of bodies. The approach is based on the equation of motion of the\npolarization and the electromagnetic potentials, which lead to coupled integral\nequations. These equations are solved, and their relevant eigenfrequencies\nbranches are identified.",
        "positive": "Magnetoresistance signature of two-dimensional electronic states in\n  Co$_3$Sn$_2$S$_2$: Two-dimensional (2D) Dirac bands and flat bands are characteristics of a\nkagome lattice. However, experimental studies on their electrical transport are\nfew, because three-dimensional (3D) bulk bands of kagome materials, consisting\nof stacked 2D kagome layers, dominate the transport. We report a\nmagnetoresistance (MR) study of a kagome material, Co$_3$Sn$_2$S$_2$. Based on\nanalysis of the temperature, magnetic field, and field angle dependence of the\nresistivity, we obtain a complete anatomy of MR. Besides a magnon MR, a\nchirality-dependent MR, and a chiral-anomaly-induced MR, the most intriguing\nfeature is an orbital MR that scales only with the out-of-plane field, which\nstrongly indicates its 2D nature. We attribute it to the Dirac band of the\nkagome lattice."
    },
    {
        "anchor": "Nonlinear magnon control of atomic spin defects in scalable quantum\n  devices: Ongoing efforts in quantum engineering have recently focused on integrating\nmagnonics into hybrid quantum architectures for novel functionalities. While\nhybrid magnon-quantum spin systems have been demonstrated with nitrogen-vacancy\n(NV) centers in diamond, they have remained elusive on the technologically\npromising silicon carbide (SiC) platform mainly due to difficulties in finding\na resonance overlap between the magnonic system and the spin centers. Here we\ncircumvent this challenge by harnessing nonlinear magnon scattering processes\nin a magnetic vortex to access magnon modes that overlap in frequency with\nsilicon-vacancy ($\\textrm{V}_{\\mathrm{Si}}$) spin transitions in SiC. Our\nresults offer a route to develop hybrid systems that benefit from marrying the\nrich nonlinear dynamics of magnons with the advantageous properties of SiC for\nscalable quantum technologies.",
        "positive": "Local density of states and scanning tunneling currents in graphene: We present exact analytical calculations of scanning tunneling currents in\nlocally disordered graphene using a multimode description of the microscope\ntip. Analytical expressions for the local density of states (LDOS) are given\nfor energies beyond the Dirac cone approximation. We show that the LDOS at the\n$A$ and $B$ sublattices of graphene are out of phase by $\\pi$ implying that the\naveraged LDOS, as one moves away from the impurity, shows no trace of the\n$2q_F$ (with $q_F$ the Fermi momentum) Friedel modulation. This means that a\nSTM experiment lacking atomic resolution at the sublattice level will not be\nable of detecting the presence of the Friedel oscillations [this seems to be\nthe case in the experiments reported in Phys. Rev. Lett. {\\bf 101}, 206802\n(2008)]. The momentum maps of the LDOS for different types of impurities are\ngiven. In the case of the vacancy, $2q_F$ features are seen in these maps. In\nall momentum space maps, $K$ and $K+K^\\prime$ features are seen. The\n$K+K^\\prime$ features are different from what is seen around zero momentum. An\ninterpretation for these features is given. The calculations reported here are\nvalid for chemical substitution impurities, such as boron and nitrogen atoms,\nas well as for vacancies. It is shown that the density of states close to the\nimpurity is very sensitive to type of disorder: diagonal, non-diagonal, or\nvacancies. In the case of weakly coupled (to the carbon atoms) impurities, the\nlocal density of states presents strong resonances at finite energies, which\nleads to steps in the scanning tunneling currents and to suppression of the\nFano factor."
    },
    {
        "anchor": "Edge stacking dislocations in two-dimensional bilayers with a small\n  lattice mismatch: Incomplete stacking dislocations are predicted to form at edges of the\nshorter upper layer in two-dimensional hexagonal bilayers upon stretching the\nlonger bottom layer. A concept of the edge Burgers vector is introduced to\ndescribe such dislocations by analogy with the Burgers vector of standard bulk\ndislocations. Analytical solutions for the structure and energy of edge\nstacking dislocations in bilayer graphene are obtained depending on the\nmagnitude of elongation and angles between the edge Burgers vector, direction\nof elongation and edge. The barrier for penetration of stacking dislocations\ninside the bilayer is estimated. The possibilities to measure the barrier to\nrelative motion of graphene layers and strain of graphene on a substrate by\nobservation of edge stacking dislocations are discussed.",
        "positive": "Static and Dynamic Oxide-Trapped-Charge-Induced Variability in Nanoscale\n  CMOS Circuits: The inter-device mismatch and intra-device temporal instability in the\nnanoscale CMOS circuits is examined from a unified point of view as a static\nand dynamic parts of the variability con-cerned with stochastic oxide charge\ntrapping and de-trapping. This approach has been benchmarked on the recent\nevidence of the radiation-induced increase of inter-transistor mismatch in 60\nnm ICs. A possible reliability limitation in ultrascale circuits concerned with\nthe single or a few charged defect instability is pointed out and estimated."
    },
    {
        "anchor": "Electric current noise in mesoscopic organic semiconductors: We demonstrate that nuclear spin fluctuations lead to the electric current\nnoise in the mesoscopic samples of organic semiconductors showing the\npronounced magnetoresistance in weak fields. For the bipolaron and\nelectron-hole mechanisms of organic magnetoresistance, the current noise\nspectrum consists of the high frequency peak related to the nuclear spin\nprecession in the Knight field of the charge carriers and the low frequency\npeak related to the nuclear spin relaxation. The shape of the spectrum depends\non the external magnetic and radiofrequency fields, which allows one to prove\nthe role of nuclei in magnetoresistance experimentally.",
        "positive": "Field Dependence of Magnetic Disorder in Nanoparticles: The performance characteristics of magnetic nanoparticles towards\napplication, e.g. in medicine, imaging, or as sensors, is directly determined\nby their magnetization relaxation and total magnetic moment. In the commonly\nassumed picture, nanoparticles have a constant overall magnetic moment\noriginating from the magnetization of the single-domain particle core\nsurrounded by a surface region hosting spin disorder. In contrast, this work\ndemonstrates the significant increase of the magnetic moment of ferrite\nnanoparticles with applied magnetic field. At low magnetic field, the\nhomogeneously magnetized particle core initially coincides in size with the\nstructurally coherent grain of 12.8(2) nm diameter, indicating a strong\ncoupling between magnetic and structural disorder. Applied magnetic fields\ngradually polarize the uncorrelated, disordered surface spins, resulting in a\nmagnetic volume more than 20\\% larger than the structurally coherent core. The\nintraparticle magnetic disorder energy increases sharply towards the\ndefect-rich surface as established by the field-dependence of the magnetization\ndistribution. In consequence, these findings illustrate how the nanoparticle\nmagnetization overcomes structural surface disorder. This new concept of\nintraparticle magnetization is deployable to other magnetic nanoparticle\nsystems, where the in-depth knowledge of spin disorder and associated magnetic\nanisotropies will be decisive for a rational nanomaterials design."
    },
    {
        "anchor": "Interface states in two-dimensional electron systems with spin-orbital\n  interaction: Interface states at a boundary between regions with different spin-orbit\ninteractions (SOIs) in two-dimensional (2D) electron systems are investigated\nwithin the one-band effective mass method with generalized boundary conditions\nfor envelope functions. We have found that the interface states unexpectedly\nexist even if the effective interface potential equals zero. Depending on the\nsystem parameters, the energy of these states can lie in either or both\nforbidden and conduction bands of bulk states. The interface states have chiral\nspin texture similar to that of the edge states in 2D topological insulators.\nHowever, their energy spectrum is more sensitive to the interfacial potential,\nthe largest effect being produced by the spin-dependent component of the\ninterfacial potential. We have also studied the size quantization of the\ninterface states in a strip of 2D electron gas with SOI and found an unusual\n(non-monotonic) dependence of the quantization energy on the strip width.",
        "positive": "Ballistic charge transport in twisted bilayer graphene: We study conductance across a twisted bilayer graphene coupled to\nsingle-layer graphene leads in two setups: a flake of graphene on top of an\ninfinite graphene ribbon and two overlapping semi-infinite graphene ribbons. We\nfind conductance strongly depends on the angle between the two graphene layers\nand identify three qualitatively different regimes. For large angles ($\\theta\n\\gtrsim 10^{\\circ}$) there are strong commensurability effects for\nincommensurate angles the low energy conductance approaches that of two\ndisconnected layers, while sharp conductance features correlate with\ncommensurate angles with small unit cells. For intermediate angles\n($3^{\\circ}\\lesssim \\theta \\lesssim 10^{\\circ}$), we find a one-to-one\ncorrespondence between certain conductance features and the twist-dependent Van\nHove singularities arising at low energies, suggesting conductance measurements\ncan be used to determine the twist angle. For small twist angles\n($1^{\\circ}\\lesssim\\theta\\lesssim 3^{\\circ}$), commensurate effects seem to be\nwashed out and the conductance becomes a smooth function of the angle. In this\nregime, conductance can be used to probe the narrow bands, with vanishing\nconductance regions corresponding to spectral gaps in the density of states, in\nagreement with recent experimental findings."
    },
    {
        "anchor": "Theory of the coherence of topological lasers: We present a theoretical study of the temporal and spatial coherence\nproperties of a topological laser device built by including saturable gain on\nthe edge sites of a Harper--Hofstadter lattice for photons. For small enough\nlattices the Bogoliubov analysis applies, the emission is nearly a single-mode\none and the coherence time is almost determined by the total number of photons\nin the device in agereement with the standard Schawlow-Townes phase diffusion.\nIn larger lattices, looking at the lasing edge mode in the comoving frame of\nits chiral motion, the spatio-temporal correlations of long-wavelength\nfluctuations display a Kardar-Parisi-Zhang (KPZ) scaling. Still, at very long\ntimes, when the finite size of the device starts to matter, the functional form\nof the temporal decay of coherence changes from the KPZ stretched exponential\nto a Schawlow-Townes-like exponential, while the nonlinear many-mode dynamics\nof KPZ fluctuations remains visible as an enhanced linewidth as compared to the\nsingle-mode Schawlow-Townes prediction. While we have established the above\nbehaviors also for non-topological laser arrays, the crucial role of topology\nin protecting the coherence from static disorder is finally highlighted: our\nground-breaking numerical calculations suggest the dramatically reinforced\ncoherence properties of topological lasers compared to corresponding\nnon-topological devices. These results open exciting possibilities for both\nfundamental studies of non-equilibrium statistical mechanics and concrete\napplications to laser devices.",
        "positive": "Fluctuation-mediated spin-orbit torque enhancement in the noncollinear\n  antiferromagnet Mn3Ni0.35Cu0.65N: The role of spin fluctuations near magnetic phase transitions is crucial for\ngenerating various exotic phenomena, including anomalies in the extraordinary\nHall effect, excess spin-current generation through the spin-Hall effect (SHE),\nand enhanced spin-pumping, amongst others. In this study, we experimentally\ninvestigate the temperature dependence of spin-orbit torques (SOTs) generated\nby Mn3Ni0.35Cu0.65N (MNCN), a member of the noncollinear antiferromagnetic\nfamily that exhibits unconventional magnetotransport properties. Our work\nuncovers a strong and nontrivial temperature dependence of SOTs, peaking near\nthe N\\'eel temperature of MNCN, which cannot be explained by conventional\nintrinsic and extrinsic scattering mechanisms of the SHE. Notably, we measure a\nmaximum SOT efficiency of 30%, which is substantially larger than that of\ncommonly studied nonmagnetic materials such as Pt. Theoretical calculations\nconfirm a negligible SHE and a strong orbital Hall effect that can explain the\nobserved SOTs. We propose a previously unidentified mechanism wherein\nfluctuating antiferromagnetic moments trigger the generation of substantial\norbital currents near the N\\'eel temperature due to the emergence of scalar\nspin chirality. Our findings present an approach for enhancing SOTs, which\nholds promise for magnetic memory applications by leveraging antiferromagnetic\nspin fluctuations to amplify both orbital and spin currents."
    },
    {
        "anchor": "Distinct magneto-Raman signatures of spin-flip phase transitions in CrI3: The discovery of 2-dimensional (2D) materials, such as CrI3, that retain\nmagnetic ordering at monolayer thickness has resulted in a surge of research in\n2D magnetism from both pure and applied perspectives. Here, we report a\nmagneto-Raman spectroscopy study on multilayered CrI3, focusing on two new\nfeatures in the spectra which appear at temperatures below the magnetic\nordering temperature and were previously assigned to high frequency magnons. We\nobserve a striking evolution of the Raman spectra with increasing magnetic\nfield in which clear, sudden changes in intensities of the modes are attributed\nto the interlayer ordering changing from antiferromagnetic to ferromagnetic at\na critical magnetic field. Our work highlights the sensitivity of the Raman\nmodes to weak interlayer spin ordering in CrI3. In addition, we theoretically\nexamine potential origins for the new modes, which we deduce are unlikely\nsingle magnons.",
        "positive": "Effect of intersubband scattering on weak localization in 2D systems: The theory of weak localization is generalized for multilevel 2D systems\ntaking into account intersubband scattering. It is shown that weak intersubband\nscattering which is negligible in a classical transport, affects strongly the\nweak-localization correction to conductivity. The anomalous magnetoresistance\nis calculated in the whole range of classically low magnetic fields. This\ncorrection to conductivity is shown to depend strongly on the ratios of\noccupied level concentrations. It is demonstrated that at relatively low\npopulation of the excited subband, it is necessary to use the present theory\nbecause the high-field limit asimptotics is shown to be achieved only in\nclassical magnetic fields."
    },
    {
        "anchor": "Aharonov-Bohm interference and the evolution of phase jumps in\n  fractional quantum Hall Fabry-Perot interferometers based on bi-layer\n  graphene: Quasi-particles in fractional quantum Hall states are collective excitations\nthat carry fractional charge and anyonic statistics. While the fractional\ncharge affects semi-classical characteristics such as shot noise and charging\nenergies, the anyonic statistics is most notable in quantum interference\nphenomena. In this study, we utilize a versatile bilayer graphene-based\nFabry-P\\'erot Interferometer (FPI) that facilitates the study of a broad\nspectrum of operating regimes, from Coulomb-dominated to Aharonov-Bohm, for\nboth integer and fractional quantum Hall states. Focusing on the $\\nu$=$1 \\over\n3$ fractional quantum Hall state, we study the Aharonov-Bohm interference of\nquasi-particles when the magnetic flux through an interference loop and the\ncharge density within the loop are independently varied. When their combined\nvariation is such that the Landau filling remains $1 \\over 3$ we observe\npristine Aharonov-Bohm oscillations with a period of three flux quanta, as is\nexpected from the interference of quasi-particles of one-third of the electron\ncharge. When the combined variation is such that it leads to quasi-particles\naddition or removal from the loop, phase jumps emerge, and alter the phase\nevolution. Notably, across all cases, the average phase consistently increases\nby 2$\\pi$ with each addition of one electron to the loop.",
        "positive": "Even-Odd-Layer-Dependent Symmetry Breaking in Synthetic Antiferromagnets: In this work we examine synthetic antiferromagnetic structures consisting of\ntwo, three, and four antiferromagnetic coupled layers, i.e., bilayers,\ntrilayers, and tetralayers. We vary the thickness of the ferromagnetic layers\nacross all structures and, using a macrospin formalism, find that the nearest\nneighbor exchange interaction between layers is consistent across all\nstructures for a given thickness. Our model and experimental results\ndemonstrate significant differences in how the magnetostatic equilibrium states\nof even and odd-layered structures evolve as a function of the external field.\nEven layered structures continuously evolve from a collinear antiferromagnetic\nstate to a spin canted non-collinear magnetic configuration that is\nmirror-symmetric about the external field. In contrast, odd-layered structures\nbegin with a ferrimagnetic ground state; at a critical field, the ferrimagnetic\nground state evolves into a non-collinear state with broken symmetry.\nSpecifically, the magnetic moments found in the odd-layered samples possess\nstable static equilibrium states that are no longer mirror-symmetric about the\nexternal field after a critical field is reached. Our results reveal the rich\nbehavior of synthetic antiferromagnets."
    },
    {
        "anchor": "Spin currents and magnetoresistance of graphene-based magnetic junctions: Using the tight-binding approximation and the nonequilibrium Green's function\napproach, we investigate the coherent spin-dependent transport in planar\nmagnetic junctions consisting of two ferromagnetic (FM) electrodes separated by\na graphene flake (GF) with zigzag or armchair interfaces. It is found that the\nelectron conduction strongly depends on the geometry of contact between the GF\nand the FM electrodes. In the case of zigzag interfaces, the junction\ndemonstrates a spin-valve effect with high magnetoresistance (MR) ratios and\nshows negative differential resistance features for a single spin channel at\npositive gate voltage. In the case of armchair interfaces, the current-voltage\ncharacteristics behave linearly at low bias voltages and hence, both spin\nchannels are in on state with low MR ratios.",
        "positive": "Spin-orbit splitting of valence subbands in semiconductor nanostructures: We propose the 14-band $\\mathbf k \\cdot \\mathbf p$ model to calculate\nspin-orbit splittings of the valence subbands in semiconductor quantum wells.\nThe reduced symmetry of quantum well interfaces is incorporated by means of\nadditional terms in the boundary conditions which mix the $\\Gamma_{15}$\nconduction and valence Bloch functions at the interfaces. It is demonstrated\nthat the interface-induced effect makes the dominating contribution to the\nheavy-hole spin splitting. A simple analytical expression for the interface\ncontribution is derived. In contrast to the 4$\\times$4 effective Hamiltonian\nmodel, where the problem of treating the $V_z k_z^3$ term seems to be\nunsolvable, the 14-band model naturally avoids and overcomes this problem. Our\nresults are in agreement with the recent atomistic calculations [J.-W. Luo et\nal., Phys. Rev. Lett. {\\bf 104}, 066405 (2010)]."
    },
    {
        "anchor": "Quantum Spin Hall Effect in Graphene: We study the effects of spin orbit interactions on the low energy electronic\nstructure of a single plane of graphene. We find that in an experimentally\naccessible low temperature regime the symmetry allowed spin orbit potential\nconverts graphene from an ideal two dimensional semimetallic state to a quantum\nspin Hall insulator. This novel electronic state of matter is gapped in the\nbulk and supports the quantized transport of spin and charge in gapless edge\nstates that propagate at the sample boundaries. The edge states are non chiral,\nbut they are insensitive to disorder because their directionality is correlated\nwith spin. The spin and charge conductances in these edge states are calculated\nand the effects of temperature, chemical potential, Rashba coupling, disorder\nand symmetry breaking fields are discussed.",
        "positive": "Enhanced spin accumulation in a superconductor: A lateral array of ferromagnetic tunnel junctions is used to inject and\ndetect non-equilibrium quasi-particle spin distribution in a superconducting\nstrip made of Al. The strip width and thickness is kept below the quasi\nparticle spin diffusion length in Al. Non-local measurements in multiple\nparallel and antiparallel magnetic states of the detectors are used to in-situ\ndetermine the quasi-particle spin diffusion length. A very large increase in\nthe spin accumulation in the superconducting state compared to that in the\nnormal state is observed and is attributed to a diminishing of the\nquasi-particle population by opening of the gap below the transition\ntemperature."
    },
    {
        "anchor": "Theory of a two-level artificial molecule in laterally coupled quantum\n  Hall droplets: We present a theory of laterally coupled quantum Hall droplets with electron\nnumbers (N1,N2) at filling factor $\\nu=2$. We show that the edge states of each\ndroplet are tunnel coupled and form a two-level artificial molecule. By\npopulating the edge states with one electron each a two electron molecule is\nformed. We predict the singlet-triplet transitions of the effective\ntwo-electron molecule as a function of the magnetic field, the number of\nelectrons, and confining potential using the configuration interaction method\n(CI) coupled with the unrestricted Hartree-Fock (URHF) basis. In addition to\nthe singlet-triplet transitions of a 2 electron molecule involving edge states,\ntriplet transitions involving transfer of electrons to the center of individual\ndots exist for $(N1 \\geq 5, N2 \\geq 5)$.",
        "positive": "Unified Framework for Charge-Spin Interconversion in Spin-Orbit\n  Materials: Materials with spin-orbit coupling are of great interest for various\nspintronics applications due to the efficient electrical generation and\ndetection of spin-polarized electrons. Over the past decade, many materials\nhave been studied, including topological insulators, transition metals, Kondo\ninsulators, semimetals, semiconductors, and oxides; however, there is no\nunifying physical framework for understanding the physics and therefore\ndesigning a material system and devices with the desired properties. We present\na model that binds together the experimental data observed on the wide variety\nof materials in a unified manner. We show that in a material with a given\nspin-momentum locking, the density of states plays a crucial role in\ndetermining the charge-spin interconversion efficiency, and a simple inverse\nrelationship can be obtained. Remarkably, experimental data obtained over the\nlast decade on many different materials closely follow such an inverse\nrelationship. We further deduce two figure-of-merits of great current interest:\nthe spin-orbit torque (SOT) efficiency (for the direct effect) and the inverse\nRashba-Edelstein effect length (for the inverse effect), which statistically\nshow good agreement with the existing experimental data on wide varieties of\nmaterials. Especially, we identify a scaling law for the SOT efficiency with\nrespect to the carrier concentration in the sample, which agrees with existing\ndata. Such an agreement is intriguing since our transport model includes only\nFermi surface contributions and fundamentally different from the conventional\nviews of the SOT efficiency that includes contributions from all the occupied\nstates."
    },
    {
        "anchor": "Supramolecular Spin Valves: Magnetic molecules possess a high potential as building blocks for the design\nof spintronic devices. Moreover, the use of molecular materials opens the way\nfor the controlled use of bottom-up, e.g. supramolecular, processing techniques\ncombining massively parallel self-fabrication with conventional top-down\nnanostructuring techniques. The development of solid state spintronic devices\nbased on the giant magnetoresistance (GMR), tunnel magnetoresistance (TMR), and\nspin valve effects has revolutionized the field of magnetic memory\napplications. Recently, organic semiconductors were inserted into nanometer\nsized tunnel junctions allowing enhancement of spin reversal, giant\nmagneto-resistance behaviour was observed in single non-magnetic molecules\ncoupled to magnetic electrodes, and the use of the quantum tunnelling\nproperties of single-molecule magnets (SMMs) in hybrid devices was proposed.\nHerein, we present an original device in which a non-magnetic molecular quantum\ndot, made of a single-wall carbon nanotube (SWCNT) contacted with non-magnetic\nelectrodes, is laterally coupled via supramolecular interactions to a TbPc2-SMM\n(Pc = phthalocyanine), which provides a localized magnetic moment. The\nconductance through the SWCNT is modulated by sweeping the magnetic field,\nexhibiting magnetoresistance ratios up to 300% between fully polarized and\nnon-polarized SMMs below 1 K. We thus demonstrate the functionality of a\nsupramolecular spin valve without magnetic leads. Our results open up prospects\nof circuit-integration and implementation of new device capabilities.",
        "positive": "Reversed Photoeffect in Transparent Graphene Nanocapacitors: Electronic properties of ultrathin dielectric films consistently attract much\nattention since they play important roles in various electronic devices, such\nas field effect transistors and memory elements. Insulating properties of the\ngate oxide in transistors represent the key factor limiting Moore's law. The\ndielectric strength of the insulating film limits how much energy can be stored\nin nanocapacitors. The origin of the electric current in the nanometer-scale\ninsulating barrier remains unexplained. Here we present an optically\ntransparent Al-Al2O3-graphene nanocapacitor suitable for studying electronic\ntransport in calibrated nanoscale dielectric films under high electric fields\nand with light exposure. The controllable flow of photons provides an\nadditional powerful probe helping to resolve the puzzle of the electric\nconductivity in these high-quality insulating films. The dielectric alumina,\nAl2O3, is deposited by atomic layer deposition technology. With this device we\nobserve a photon-assisted field emission effect, in which the effective barrier\nheight is reduced by a quantity equal to the photon energy. Our main finding is\na reversed photoeffect. Namely, at sufficiently high bias voltages the current\nthrough the dielectric film decreases as the light intensity increases.\nMoreover, higher photon energies correlate with stronger decreases of the\ncurrent. To explain this reversed photoeffect, we present a qualitative model\nbased on a conjecture that electrons leak into the dielectric and form charged\nsandpile-like branching patterns, which facilitate transport, and which can be\ndispersed by light."
    },
    {
        "anchor": "Spin-Orbit gauge and quantum spin Hall effect: We have shown that the non-Abelian spin-orbit gauge field strength of the\nRashba and Dresselhaus interactions, when split into two Abelian field\nstrengths, the Hamiltonian of the system can be re-expressed as a Landau level\nproblem with a particular relation between the two coupling parameters. The\nquantum levels are created with up and down spins with opposite chirality and\nleads to the quantum spin Hall effect.",
        "positive": "Tension tuning of sound and heat transport in graphene: Heat transport by acoustic phonons in 2D materials is fundamentally different\nfrom that in 3D crystals because the out-of-plane phonons propagate in a unique\nway that strongly depends on tension and bending rigidity. Since in-plane and\nout-of-plane phonon baths are decoupled, initial studies suggested they provide\nindependent pathways for heat transport and storage in 2D materials. Here, we\ninduce tension in freestanding graphene membranes by electrostatic force, and\nuse optomechanical techniques to demonstrate that it can change the rate of\nheat transport by as much as 33%. Using a ballistic Debye model, we account for\nthese observations and extract the average bending rigidity of the flexural\nacoustic phonons, which increases approximately linearly with the membrane's\nareal mass density, in contrast to the cubic dependence seen in bulk\nstructures. Thus, we not only elucidate phononic heat transport mechanisms in\nsuspended 2D materials, but also provide a promising route for controlling\nnanoscale heat transport by tension."
    },
    {
        "anchor": "First-principles calculations of the magnetism of Fe$_2$O$_2$H$_2$: By expanding the wave function in plane waves, we use the pseudopotential\nmethod of density functional theory within the generalized gradient\napproximation to calculate the effective magnetic coupling energies of the\nS=5/2 spins in the Fe2 dimer, approximated as Fe$_2$O$_2$H$_2$. Setting the\nFe-O bond length at the value corresponding to the minimum total energy, we\nfind the difference in antiferromagnetic and ferromagnetic exchange energies as\na function of the Fe-O-Fe bond angle $\\theta$. The effective interaction is\nantiferromagnetic for 63$^{\\circ}<\\theta<105^{\\circ}$, and is ferromagnetic\notherwise. Full potential augmented plane wave calculations were also performed\nat $\\theta=100,105^{\\circ}$, confirming these results, and providing\ninformation relevant to the local anisotropy of the spin interactions.",
        "positive": "Thermally-Activated Phase Slips in Superfluid Spin Transport in Magnetic\n  Wires: We theoretically study thermally-activated phase slips in superfluid spin\ntransport in easy-plane magnetic wires within the stochastic\nLandau-Lifshitz-Gilbert phenomenology, which runs parallel to the\nLanger-Ambegaokar-McCumber-Halperin theory for thermal resistances in\nsuperconducting wires. To that end, we start by obtaining the exact solutions\nfor free-energy minima and saddle points. We provide an analytical expression\nfor the phase-slip rate in the zero spin-current limit, which involves detailed\nanalysis of spin fluctuations at extrema of the free energy. An experimental\nsetup of a magnetoeletric circuit is proposed, in which thermal phase slips can\nbe inferred by measuring nonlocal magnetoresistance."
    },
    {
        "anchor": "Enhancing heat transfer in nanofluids by carbon nanofins: Nanofluids are suspensions of nanoparticles and fibers which have recently\nattracted much attention due to their superior thermal properties. Here,\nnanofluids are studied in the sense of nanofins transversally attached to a\nsurface, so that dispersion within a fluid is mainly dictated by design and\nmanufacturing processes. We focus on single carbon nanotubes thought as\nnanofins to enhance heat transfer between a surface and a fluid in contact with\nit. To this end, we first investigate the thermal conductivity of those\nnanostructures by means of classical non-equilibrium molecular dynamics\nsimulations. Next, thermal conductance at the interface between a single wall\ncarbon nanotube (nanofin) and water molecules is assessed by means of both\nsteady-state and transient numerical experiments. Numerical evidences suggest a\npretty favorable thermal boundary conductance (order of $10^{-7}$ $[W m^{-2}\nK^{-1}]$) which makes carbon nanotubes ideal candidates for constructing\nnanofinned surfaces.",
        "positive": "PtSi Clustering In Silicon Probed by Transport Spectroscopy: Metal silicides formed by means of thermal annealing processes are employed\nas contact materials in microelectronics. Control of the structure of\nsilicide/silicon interfaces becomes a critical issue when the device\ncharacteristic size is reduced below a few tens of nanometers. Here we report\non silicide clustering occurring within the channel of PtSi/Si/PtSi Schottky\nbarrier transistors. This phenomenon is investigated through atomistic\nsimulations and low-temperature resonant tunneling spectroscopy. Our results\nprovide evidence for the segregation of a PtSi cluster with a diameter of a few\nnanometers from the silicide contact. The cluster acts as metallic quantum dot\ngiving rise to distinct signatures of quantum transport through its discrete\nenergy states."
    },
    {
        "anchor": "Interaction confinement and electronic screening in two-dimensional\n  nanofluidic channels: The transport of fluids at the nanoscale is fundamental to manifold\nbiological and industrial processes, ranging from neurotransmission to\nultrafiltration. Yet, it is only recently that well-controlled channels with\ncross-sections as small as a few molecular diameters became an experimental\nreality. When aqueous electrolytes are confined within such channels, the\nCoulomb interactions between the dissolved ions are reinforced due to\ndielectric contrast at the channel walls: we dub this effect `interaction\nconfinement'. Yet, no systematic way of computing these confined interactions\nhas been proposed beyond the limiting cases of perfectly metallic or perfectly\ninsulating channel walls. Here, we introduce a new formalism, based on the\nso-called surface response functions, that expresses the effective Coulomb\ninteractions within a two-dimensional channel in terms of the wall's electronic\nstructure, described to any desired level of precision. We use it to\ndemonstrate that in few-nanometer-wide channels, the ionic interactions can be\ntuned by the wall material's screening length. We illustrate this approach by\nimplementing these interactions in brownian dynamics simulations of a strongly\nconfined electrolyte, and show that the resulting ionic conduction can be\nadjusted between Ohm's law and a Wien effect behavior. Our results provide a\nquantitative approach to tuning nanoscale ion transport through the electronic\nproperties of the channel wall material.",
        "positive": "On the origin of the giant SHE in Cu(Bi) alloys: Two years after the prediction of a giant spin Hall effect for the dilute\nCu(Bi) alloy [Gradhand et al., Phys. Rev. B 81, 245109 (2010)], a comparably\nstrong effect was measured in thin films of Cu(Bi) alloys by Niimi et al.\n[Phys. Rev. Lett. 109, 156602 (2012)]. Both theory and experiment consider the\nskew-scattering mechanism to be responsible, however they obtain opposite sign\nfor the spin Hall angle. Based on a detailed analysis of existing theoretical\nresults, we explore differences between theory and experiment."
    },
    {
        "anchor": "Microwave-induced resistance oscillations in tilted magnetic fields: We have studied the effect of an in-plane magnetic field on microwave-induced\nresistance oscillations in a high mobility two-dimensional electron system. We\nhave found that the oscillation amplitude decays exponentially with an in-plane\ncomponent of the magnetic field $B_\\parallel$. While these findings cannot be\naccounted for by existing theories, our analysis suggests that the decay can be\nexplained by a $B_\\parallel$-induced correction to the quantum scattering rate,\nwhich is quadratic in $B_\\parallel$.",
        "positive": "Spin filtering through excited states in double quantum dot pumps: Recently it has been shown that ac-driven double quantum dots can act as spin\npumps and spin filters. By calculating the current through the system for each\nspin polarization, by means of the time evolution of the reduced density matrix\nin the sequential tunneling regime (Born-Markov approximation), we demonstrate\nthat the spin polarization of the current can be controlled by tuning the\nparameters (amplitude and frequency) of the ac field. Importantly, the pumped\ncurrent as a function of the applied frequency presents a series of peaks which\nare uniquely associated with a definite spin polarization. We discuss how\nexcited states participating in the current allow the system to behave as a\nbipolar spin filter by tuning the ac frequency and intensity. We also discuss\nspin relaxation and decoherence effects in the pumped current and show that\nmeasuring the width of the current vs frequency peaks allows to determine the\nspin decoherence time $T_{2}$."
    },
    {
        "anchor": "Interfacing nuclear spins in quantum dots to cavity or traveling-wave\n  fields: We show how to realize a quantum interface between optical fields and the\npolarized nuclear spins in a singly charged quantum dot, which is strongly\ncoupled to a high-finesse optical cavity. An effective direct coupling between\ncavity and nuclear spins is obtained by adiabatically eliminating the (far\ndetuned) excitonic and electronic states. The requirements needed to map qubit\nand continuous variable states of cavity or traveling-wave fields to the\ncollective nuclear spin are investigated: For cavity fields, we consider\nadiabatic passage processes to transfer the states. It is seen that a\nsignificant improvement in cavity lifetimes beyond present-day technology would\nbe required for a quantum interface. We then turn to a scheme which couples the\nnuclei to the output field of the cavity and can tolerate significantly shorter\ncavity lifetimes. We show that the lifetimes reported in the literature and the\nrecently achieved nuclear polarization of ~90% allow both high-fidelity\nread-out and write-in of quantum information between the nuclear spins and the\noutput field. We discuss the performance of the scheme and provide a convenient\ndescription of the dipolar dynamics of the nuclei for highly polarized spins,\ndemonstrating that this process does not affect the performance of our\nprotocol.",
        "positive": "Transport in gapped bilayer graphene: the role of potential fluctuations\n  (Supplementary Information): Online Supplementary Information for arXiv:1008.0783"
    },
    {
        "anchor": "Oscillations of magnetoresistance in a clean hollow cylinder with\n  fluctuating radius: We consider magnetic oscillations of resistivity of a clean hollow cylinder\nwith fluctuating radius $R$, threaded by magnetic flux $\\Phi$. We demonstrate,\nthat for very weak fluctuations $\\Delta R\\ll p_F^{-1}$ the oscillations have a\nstandard period $2\\Phi_0$ (where $\\Phi_0=\\pi c\\hbar/2e$), characteristic for\noscillations in a clean system, while for $\\Delta R\\gg p_F^{-1}$ they become\n$\\Phi_0$-periodic, which was expected only for dirty systems with $R\\gg l$. The\nwork is motivated by observation of predominantly $\\Phi_0$-periodic magnetic\noscillations in very clean Bismuth wires.",
        "positive": "Landau-Zener-Stuckelberg-Majorana interferometry of a single hole: We perform Landau-Zener-Stuckelberg-Majorana (LZSM) spectroscopy on a system\nwith strong spin-orbit interaction (SOI), realized as a single hole confined in\na gated double quantum dot. In analogy to the electron systems, at magnetic\nfield B=0 and high modulation frequencies we observe the photon-assisted\ntunneling (PAT) between dots, which smoothly evolves into the typical LZSM\nfunnel-shaped interference pattern as the frequency is decreased. In contrast\nto electrons, the SOI enables an additional, efficient spin-flipping interdot\ntunneling channel, introducing a distinct interference pattern at finite B.\nMagneto-transport spectra at low-frequency LZSM driving show the two channels\nto be equally coherent. High-frequency LZSM driving reveals complex\nphoton-assisted tunneling pathways, both spin-conserving and spin-flipping,\nwhich form closed loops at critical magnetic fields. In one such loop an\narbitrary hole spin state is inverted, opening the way toward its\nall-electrical manipulation."
    },
    {
        "anchor": "Pure dephasing of magnonic quantum states: For a wide range of nonclassical magnonic states that have been proposed and\ndemonstrated recently, a new time scale besides the magnon lifetime - the\nmagnon dephasing time - becomes important, but this time scale is rarely\nstudied. Considering exchange interaction and spin-phonon coupling, we evaluate\nthe pure magnon dephasing time and find it to be smaller than the magnon\nlifetime at temperatures of a few Kelvins. By examining a magnonic cat state as\nan example, we show how pure dephasing of magnons destroys and limits the\nsurvival of quantum superpositions. Thus it will be critical to perform quantum\noperations within the pure dephasing time. We further derive the master\nequation for the density matrix describing such magnonic quantum states taking\ninto account the role of pure dephasing, whose methodology can be generalized\nto include additional dephasing channels that experiments are likely to\nencounter in the future. Our findings enable one to design and manipulate\nrobust quantum states of magnons for information processing.",
        "positive": "Introduction to {\\it Quantum Matter}: This paper records my opening remarks at Nobel Symposium 148, on Graphene and\nQuantum Matter, at Saltsj\\\"obaden, Sweden, in June 2010. After some broad\ncomments on the quantum theory of matter as a frontier of physics, and some\nslightly more particular comments about re-quantization, I report on the\nuniversal geometry that arises in a refined discussion of quantum-mechanical\nlevel crossing."
    },
    {
        "anchor": "Excitonic condensation of massless fermions in graphene bilayers: Graphene, a single sheet of graphite with honeycomb lattice structure, has\nmassless carriers with tunable density and polarity. We investigate the ground\nstate phase diagram of two graphene sheets (embedded in a dielectric) separated\nby distance $d$ where the top layer has electrons and the bottom layer has\nholes, using mean-field theory. We find that a uniform excitonic condensate\noccurs over a large range of carrier densities and is weakly dependent on the\nrelative orientation of the two sheets. We obtain the excitonic gap,\nquasiparticle energy and the density of states. We show that both, the\ncondensate phase stiffness and the mass of the excitons, with massless\nparticles as constituents, vary as the square-root of the carrier density, and\npredict that the condensate will not undergo Wigner crystallization.",
        "positive": "Response to noise of a spin transfer vortex based nano-oscillator: We investigate experimentally and analytically the impact of thermal noise on\nthe sustained gyrotropic mode of vortex magnetization in spin transfer\nnano-oscillators and its consequence on the linewidth broadening due to the\ndifferent nonlinear contributions. Performing some time domain measurements, we\nare able to extract separately the phase noise and the amplitude noise at room\ntemperature for several values of dc current and perpendicular field. For a\ntheoretical description of the experiments, we extend the general model of\nnonlinear auto-oscillators to the case of vortex core dynamics and provide some\nanalytical expressions of the response-to-noise of the system as the coupling\ncoefficient between the phase and the amplitude of the vortex core dynamics due\nto the nonlinearities. From the analysis of our experimental results, we\ndemonstrate the major role of the amplitude-to-phase noise conversion on the\nlinewidth broadening, and propose some solutions to improve the spectral\ncoherence of vortex based spin transfer nano-oscillators."
    },
    {
        "anchor": "Plasmon modes in bilayer-monolayer graphene heterostructures: We investigate the dispersion relation and damping of plasmon modes in a\nbilayer-monolayer graphene heterostructure with carrier densities and at zero\ntemperature within the random-phase-approximation taking into account the\nnonhomogeneity of the dielectric background of the system. We derive analytical\nexpressions for plasmon frequencies by using long wavelength expansion of\nresponse and bare Coulomb interaction functions. We show that optical plasmon\ndispersion curve of the bilayer-monolayer system lies slightly below that of\ndouble-layer graphene (DLG) and the acoustic one lies much lower than that of\nDLG. We find that while decay rates of acoustic modes of the system and DLG are\nremarkably different, those of optical modes in both double-layer systems are\nsimilar. Except the damping rate of acoustic mode, properties of plasmon\nexcitations in considered system depend remarkably on the interlayer distance,\ninhomogeneity of the background, density ratio and spacer dielectric constant,\nespecially at large wave-vectors.",
        "positive": "Electron Spin Dephasing due to Hyperfine Interactions with a Nuclear\n  Spin Bath: We investigate pure dephasing decoherence (free induction decay and spin\necho) of a spin qubit interacting with a nuclear spin bath. While for infinite\nmagnetic field B the only decoherence mechanism is spectral diffusion due to\ndipolar flip-flops of nuclear spins, with decreasing B the hyperfine-mediated\ninteractions between the nuclear spins become important. We give a theory of\ndecoherence due to these interactions which takes advantage of their long-range\nnature. For a thermal uncorrelated bath we show that our theory is applicable\ndown to B~10 mT, allowing for comparison with recent experiments in GaAs\nquantum dots."
    },
    {
        "anchor": "Impact of chemical potential on the reflectance of graphene in the\n  infrared and microwave domains: The reflectance of graphene is investigated in the framework of the Dirac\nmodel with account of its realistic properties, such as nonzero chemical\npotential and band gap, at any temperature. For this purpose, the exact\nreflection coefficients of the electromagnetic waves on a graphene sheet\nexpressed via the polarization tensor and ultimately via the electrical\nconductivity of graphene have been used. The reflectance of graphene is\ncomputed as a function of frequency and chemical potential at different\ntemperatures and values of the band-gap parameter. The minimum values of the\nreflectance are found which are reached in the infrared domain at the points of\nvanishing imaginary part of the conductivity of graphene. For a gapped\ngraphene, the maximum reflectance equal to unity is reached at the points where\nthe imaginary part of conductivity diverges. The computational results\ndemonstrate an interesting interplay between the band gap and chemical\npotential in their combined effect on the reflectance. Specifically, there are\nwide frequency intervals where the reflectance of graphene increases with\nincreasing chemical potential and decreasing band gap. The numerical\ncomputations are found to be in good agreement with the analytic asymptotic\nexpressions in the regions of their applicability. Several technological areas,\nwhere the obtained results could be used, are listed.",
        "positive": "A parylene coating system specifically designed for producing ultra-thin\n  films for nanoscale device applications: We report on a parylene chemical vapor deposition system custom designed for\nproducing ultra-thin parylene films (5-100 nm thickness) for use as an\nelectrical insulator in nanoscale electronic devices, including as the gate\ninsulator in transistors. The system features a small deposition chamber that\ncan be isolated and purged for process termination, a quartz crystal\nmicrobalance for monitoring deposition, and a rotating angled stage to increase\ncoating conformity. The system was mostly built from off-the-shelf vacuum\nfittings allowing for easy modification and reduced cost compared to commercial\nparylene coating systems. The production of ultra-thin parylene films for\ndevice applications is a niche not well catered to by commercial coating\nsystems, which are typically designed to give thicker coatings (microns) with\nhigh uniformity over much larger areas. An added advantage of our design for\nnanoscale device applications is that the small deposition chamber is readily\nremovable for transfer to a glovebox to enable parylene deposition onto\npristine surfaces prepared in oxygen/water-free environments with minimal\ncontamination."
    },
    {
        "anchor": "Dynamic stiffness of spin valves: The dynamics of the magnetic order parameters of\nferromagnet/normal-metal/ferromagnet spin valves and isolated ferromagnets may\nbe very different. We investigate the role of the nonequilibrium spin-current\nexchange between the ferromagnets in the magnetization precession and\nswitching. We find a (low-temperature) critical current bias for a coherent\ncurrent-induced magnetization excitation in spin valves, which unifies and\ngeneralizes previous ideas of Slonczewski and Berger. In the absence of an\napplied bias, the effect of the spin transfer can be expressed as\nmagnetic--configuration-dependent Gilbert damping.",
        "positive": "Partial nonlinear reciprocity breaking through ultrafast dynamics in a\n  random photonic medium: We demonstrate that ultrafast nonlinear dynamics gives rise to reciprocity\nbreaking in a random photonic medium. Reciprocity breaking is observed via the\nsuppression of coherent backscattering, a manifestation of weak localization of\nlight. The effect is observed in a pump-probe configuration where the pump\ninduces an ultrafast step-change of the refractive index during the dwell time\nof the probe light in the material. The dynamical suppression of coherent\nbackscattering is reproduced well by a multiple scattering Monte Carlo\nsimulation. Ultrafast reciprocity breaking provides a distinct mechanism in\nnonlinear optical media which opens up avenues for the active manipulation of\nmesoscopic transport, random lasers, and photon localization."
    },
    {
        "anchor": "Collective and independent-particle motion in two-electron artificial\n  atoms: Investigations of the exactly solvable excitation spectra of two-electron\nquantum dots with a parabolic confinement, for different values of the\nparameter R_W expressing the relative magnitudes of the interelectron repulsion\nand the zero-point kinetic energy of the confined electrons, reveal for large\nR_W a remarkably well-developed ro-vibrational spectrum associated with\nformation of a linear trimeric rigid molecule composed of the two electrons and\nthe infinitely heavy confining dot. This spectrum transforms to one\ncharacteristic of a \"floppy\" molecule for smaller values of R_W. The\nconditional probability distribution calculated for the exact two-electron wave\nfunctions allows for the identification of the ro-vibrational excitations as\nrotations and stretching/bending vibrations, and provides direct evidence\npertaining to the formation of such molecules.",
        "positive": "Detecting entanglement using a double quantum dot turnstile: We propose a scheme based on using the singlet ground state of an electron\nspin pair in a double quantum dot nanostructure as a suitable set-up for\ndetecting entanglement between electron spins via the measurement of an optimal\nentanglement witness. Using time-dependent gate voltages and magnetic fields\nthe entangled spins are separated and coherently rotated in the quantum dots\nand subsequently detected at spin-polarized quantum point contacts. We analyze\nthe coherent time evolution of the entangled pair and show that by counting\ncoincidences in the four exits an entanglement test can be done. This set-up is\nclose to present-day experimental possibilities and can be used to produce\npairs of entangled electrons ``on demand''."
    },
    {
        "anchor": "Magnetically switchable spin wave retarder with $90^\\circ$\n  antiferromagnetic domain wall: Polarization, denoting the precession direction with respect to the\nbackground magnetization, is an intrinsic degree of freedom of spin wave. Using\nmagnetic textures to control the spin wave polarization is fundamental and\nindispensable toward reprogrammable polarization-based magnonics. Here, we show\nthat due to the intrinsic cubic anisotropy, a $90^\\circ$ antiferromagnetic\ndomain wall naturally acts as a spin wave retarder (wave-plate). Moreover, for\na $90^\\circ$ domain wall pair developed by introducing a second domain in a\nhomogenous antiferromagnetic wire, the sign of retarding effect can be flipped\nby simply switching the direction of the intermediate domain.",
        "positive": "Orbital Picture of Yu-Shiba-Rusinov Multiplets: We investigate the nature of Yu-Shiba-Rusinov (YSR) subgap states induced by\nsingle Manganese (Mn) atoms adsorbed on different surface orientations of\nsuperconducting lead (Pb). Depending on the adsorption site, we detect a\ndistinct number and characteristic patterns of YSR states around the Mn atoms.\nWe suggest that the YSR states inherit their properties from the Mn $d$-levels,\nwhich are split by the surrounding crystal field. The periodicity of the\nlong-range YSR oscillations allows us to identify a dominant coupling of the\nd-states to the outer Fermi sheet of the two-band superconductor Pb."
    },
    {
        "anchor": "Plasmonics in Dirac systems: from graphene to topological insulators: The recent developments in the emerging field of plasmonics in graphene and\nother Dirac systems are reviewed and a comprehensive introduction to the\nstandard models and techniques is given. In particular, we discuss intrinsic\nplasmon excitations of single and bilayer graphene via hydrodynamic equations\nand the random phase approximation, but also comment on double and multilayer\nstructures. Additionally, we address Dirac systems in the retardation limit and\nalso with large spin-orbit coupling including topological insulators. Finally,\nwe summarize basic properties of the charge, current and photon linear response\nfunctions in an appendix.",
        "positive": "Two-dimensional Bloch electrons in perpendicular magnetic fields: an\n  exact calculation of the Hofstadter butterfly spectrum: The problem of two-dimensional, independent electrons subject to a periodic\npotential and a uniform perpendicular magnetic field unveils surprisingly rich\nphysics, as epitomized by the fractal energy spectrum known as Hofstadter's\nButterfly. It has hitherto been addressed using various approximations rooted\nin either the strong potential or the strong field limiting cases. Here we\nreport calculations of the full spectrum of the single-particle Schr\\\"{o}dinger\nequation without further approximations. Our method is exact, up to numerical\nprecision, for any combination of potential and uniform field strength. We\nfirst study a situation that corresponds to the strong potential limit, and\ncompare the exact results to the predictions of a Hofstadter-like model. We\nthen go on to analyze the evolution of the fractal spectrum from a Landau-like\nnearly-free electron system to the Hofstadter tight-binding limit by tuning the\namplitude of the modulation potential."
    },
    {
        "anchor": "Field-free switching of magnetic tunnel junctions driven by spin-orbit\n  torques at sub-ns timescales: We report time-resolved measurements of magnetization switching by spin-orbit\ntorques in the absence of an external magnetic field in perpendicularly\nmagnetized magnetic tunnel junctions (MTJ). Field-free switching is enabled by\nthe dipolar field of an in-plane magnetized layer integrated above the MTJ\nstack, the orientation of which determines the switching polarity. Real-time\nsingle-shot measurements provide direct evidence of magnetization reversal and\nswitching distributions. Close to the critical switching voltage we observe\nstochastic reversal events due to a finite incubation delay preceding the\nmagnetization reversal. Upon increasing the pulse amplitude to twice the\ncritical voltage the reversal becomes quasi-deterministic, leading to reliable\nbipolar switching at sub-ns timescales in zero external field. We further\ninvestigate the switching probability as a function of dc bias of the MTJ and\nexternal magnetic field, providing insight on the parameters that determine the\ncritical switching voltage.",
        "positive": "Hyperbolic Spin Waves in Magnetic Polar Metals: We demonstrate the emergence of collective spin modes with hyperbolic\ndispersion in three-dimensional spin-orbit coupled polar metals magnetized by\nintrinsic ordering or applied fields. These particle-hole bound states exist\nfor arbitrarily weak repulsive interactions; they are optically accessible and\ncan be used to generate pure spin current when magnetization is tilted away\nfrom the polar axis. We suggest material hosts for these excitations and\ndiscuss their potential relevance to nanoscale spintronic and polaritonic\napplications."
    },
    {
        "anchor": "Charge distribution and screening in layered graphene systems: The charge distribution induced by external fields in finite stacks of\ngraphene planes, or in semiinfinite graphite is considered. The interlayer\nelectronic hybridization is described by a nearest neighbor hopping term, and\nthe charge induced by the self consistent electrostatic potential is calculated\nwithin linear response (RPA). The screening properties are determined by\ncontributions from inter- and intraband electronic transitions. In neutral\nsystems, only interband transitions contribute to the charge polarizability,\nleading to insulating-like screening properties, and to oscillations in the\ninduced charge, with a period equal to the interlayer spacing. In doped\nsystems, we find a screening length equivalent to 2-3 graphene layers,\nsuperimposed to significant charge oscillations.",
        "positive": "Dynamic strain modulation of a nanowire quantum dot compatible with a\n  thin-film lithium niobate photonic platform: The integration of on-demand single photon sources in photonic circuits is a\nmajor prerequisite for on-chip quantum applications. Among the various\nhigh-quality sources, nanowire quantum dots can be efficiently coupled to\noptical waveguides because of their preferred emission direction along their\ngrowth direction. However, local tuning of the emission properties remains\nchallenging. In this work, we transfer a nanowire quantum dot on a bulk lithium\nniobate substrate and show that its emission can be dynamically tuned by\nacousto-optical coupling with surface acoustic waves. The purity of the single\nphoton source is preserved during the strain modulation. We further demonstrate\nthat the transduction is maintained even with a SiO2 encapsulation layer\ndeposited on top of the nanowire acting as the cladding of a photonic circuit.\nBased on these experimental findings and numerical simulations, we introduce a\ndevice architecture consisting of a nanowire quantum dot efficiently coupled to\na thin film lithium niobate rib waveguide and strain-tunable by surface\nacoustic waves."
    },
    {
        "anchor": "Quantum dot Rabi rotations beyond the weak exciton-phonon coupling\n  regime: We study the excitonic dynamics of a driven quantum dot under the influence\nof a phonon environment, going beyond the weak exciton-phonon coupling\napproximation. By combining the polaron transform and time-local projection\noperator techniques we develop a master equation that can be valid over a much\nlarger range of exciton-phonon coupling strengths and temperatures than the\nstandard weak-coupling approach. For the experimentally relevant parameters\nconsidered here, we find that the weak-coupling and polaron theories give very\nsimilar predictions for low temperatures (below 30 K), while at higher\ntemperatures we begin to see discrepancies between the two. This is due to the\nfact that, unlike the polaron approach, the weak-coupling theory is incapable\nof capturing multiphonon effects, while it also does not properly account for\nphonon-induced renormalisation of the driving frequency. In particular, we find\nthat the weak-coupling theory often overestimates the damping rate when\ncompared to that predicted by the polaron theory. Finally, we extend our theory\nto include non-Markovian effects and find that, for the parameters considered\nhere, they have little bearing on the excitonic Rabi rotations when plotted as\na function of pulse area.",
        "positive": "Semiconductor quantum plasmonics: We investigate the frontier between classical and quantum plasmonics in\nhighly doped semiconductor layers. The choice of a semiconductor platform\ninstead of metals for our study permits an accurate description of the quantum\nnature of the electrons constituting the plasmonic response, which is a crucial\nrequirement for quantum plasmonics. Our quantum model allows us to calculate\nthe collective plasmonic resonances from the electronic states determined by an\narbitrary one-dimensional potential. Our approach is corroborated with\nexperimental spectra, realized on a single quantum well, in which higher order\nlongitudinal plasmonic modes are present. We demonstrate that their energy\ndepends on the plasma energy, as it is also the case for metals, but also on\nthe size confinement of the constituent electrons. This work opens the way\ntowards the applicability of quantum engineering techniques for semiconductor\nplasmonics."
    },
    {
        "anchor": "Modulation of Landau levels and de Haas-van Alphen oscillation in\n  magnetized graphene by uniaxial tensile strain/ stress: The strain engineering technique allows us to alter the electronic properties\nof graphene in various ways. Within the continuum approximation, the influences\nof strain result in the appearance of a pseudo-gauge field and modulated Fermi\nvelocity. In this study, we investigate theoretically the effect of linear\nuniaxial tensile strain and/or stress, which makes the Fermi velocity\nanisotropic, on a magnetized graphene sheet in the presence of an applied\nelectrostatic voltage. More specifically, we analyze the consequences of the\nanisotropic nature of the Fermi velocity on the structure Landau levels and de\nHaas - van Alphen (dHvA) quantum oscillation in the magnetized graphene sheet.\nThe effect of the direction of the applied strain has also been discussed.",
        "positive": "Ab initio modelling of quantum dot qubits: Coupling, gate dynamics and\n  robustness versus charge noise: Electron spins in semiconductor devices are highly promising building blocks\nfor quantum processors (QPs). Commercial semiconductor foundries can create QPs\nusing the same processes employed for conventional chips, once the QP design is\nsuitably specified. There is a vast accessible design space; to identify the\nmost promising options for fabrication, one requires predictive modeling of\ninteracting electrons in real geometries and complex non-ideal environments. In\nthis work we explore a modelling method based on real-space grids, an ab initio\napproach without assumptions relating to device topology and therefore with\nwide applicability. Given an electrode geometry, we determine the exchange\ncoupling between quantum dot qubits, and model the full evolution of a\n$\\sqrt{\\text{SWAP}}$ gate to predict qubit loss and infidelity rates for\nvarious voltage profiles. Moreover we explore the impact of unwanted charge\ndefects (static and dynamic) in the environment, and test robust pulse\nsequences. As an example we exhibit a sequence correcting both systematic\nerrors and (unknown) charge defects, observing an order of magnitude boost in\nfidelity. The technique can thus identify the most promising device designs for\nfabrication, as well as bespoke control sequences for each such device."
    },
    {
        "anchor": "Coulomb interaction signatures in self-assembled lateral quantum dot\n  molecules: We use photoluminescence spectroscopy to investigate the ground state of\nsingle self-assembled InGaAs lateral quantum dot molecules. We apply a voltage\nalong the growth direction that allows us to control the total charge occupancy\nof the quantum dot molecule. Using a combination of computational modeling and\nexperimental analysis, we assign the observed discrete spectral lines to\nspecific charge distributions. We explain the dynamic processes that lead to\nthese charge configurations through electrical injection and optical\ngeneration. Our systemic analysis provides evidence of inter-dot tunneling of\nelectrons as predicted in previous theoretical work.",
        "positive": "Local field enhancement and thermoplasmonics in multimodal Aluminum\n  structures: Aluminum nanostructures have recently been at the focus of numerous studies\ndue to their properties including oxidation stability and surface plasmon\nresonances covering the ultraviolet and visible spectral windows. In this\narticle, we reveal a new facet of this metal relevant for both plasmonics\npurpose and photo-thermal conversion. The field distribution of high order\nplasmonic resonances existing in two-dimensional Al structures is studied by\nnonlinear photoluminescence (nPL) microscopy in a spectral region where\nelectronic interband transitions occur. The polarization sensitivity of the\nfield intensity maps shows that the electric field concentration can be\naddressed and controlled on-demand. We use a numerical tool based on the Green\ndyadic method to analyze our results and to simulate the absorbed energy that\nis locally converted into heat. The polarization-dependent temperature increase\nof the Al structures is experimentally quantitatively measured, and is in an\nexcellent agreement with theoretical predictions. Our work highlights Al as a\npromising candidate for designing thermal nanosources integrated in coplanar\ngeometries for thermally assisted nanomanipulation or biophysical applications."
    },
    {
        "anchor": "Semicircle: An exact relation in the Integer and Fractional Quantum Hall\n  Effect: We present experimental results on the quantized Hall insulator in two\ndimensions. This insulator, with vanishing conductivities, is characterized by\nthe quantization (within experimental accuracy) of the Hall resistance in units\nof the quantum unit of resistance, h/e^2. The measurements were performed in a\ntwo dimensional hole system, confined in a Ge/SiGe quantum well, when the\nmagnetic field is increased above the nu=1 quantum Hall state. This\nquantization leads to a nearly perfect semi-circle relation for the diagonal\nand Hall conductivities. Similar results are obtained with a higher mobility\nn-type modulation doped GaAs/AlGaAs sample, when the magnetic field is\nincreased above the nu=1/3 fractional quantum Hall state.",
        "positive": "Localization Length Exponent, Critical Conductance Distribution and\n  Multifractality in Hierarchical Network Models for the Quantum Hall Effect: We study hierarchical network models which have recently been introduced to\napproximate the Chalker-Coddington model for the integer quantum Hall effect\n(A.G. Galstyan and M.E. Raikh, PRB 56 1422 (1997); Arovas et al., PRB 56, 4751\n(1997)). The hierarchical structure is due to a recursive method starting from\na finite elementary cell. The localization-delocalization transition occurring\nin these models is displayed in the flow of the conductance distribution under\nincreasing system size. We numerically determine this flow, calculate the\ncritical conductance distribution, the critical exponent of the localization\nlength, and the multifractal exponents of critical eigenstates."
    },
    {
        "anchor": "Excess charges as a probe of one-dimensional topological crystalline\n  insulating phases: We show that in conventional one-dimensional insulators excess charges\ncreated close to the boundaries of the system can be expressed in terms of the\nBerry phases associated with the electronic Bloch wave functions. Using this\ncorrespondence, we uncover a link between excess charges and the topological\ninvariants of the recently classified one-dimensional topological phases\nprotected by spatial symmetries. Excess charges can be thus used as a probe of\ncrystalline topologies.",
        "positive": "Interlayer interaction controlling the properties of AB- and AA-stacked\n  bilayer graphene-like BC$_{14}$N and Si$_{2}$C$_{14}$: We model bilayer graphene-like materials with Si$_2$C$_{14}$ and BC$_{14}$N\nstoichiometry, where the interlayer interactions play important roles shaping\nthe physical properties of the systems. We find the interlayer interaction in\nSi$_2$C$_{14}$ to be repulsive due to the interaction of Si-Si atoms, and in\nBC$_{14}$N it is attractive due to B and N atoms for both the AA- and the\nAB-stacking. The repulsive interlayer interaction opens up a bandgap in\nSi$_2$C$_{14}$ while the attractive interlayer interaction in BC$_{14}$N\ninduces a small indirect bandgap or overlaping of the valence conduction bands.\nFurthermore, the repulsive interaction decreases the Young modulus while the\nattractive interaction does not influence the Young modulus much. The\nstress-strain curves of both the AA- and the AB-stackings are suppressed\ncompared to pure graphine bilayers. The optical response of Si$_2$C$_{14}$ is\nvery sensitive to an applied electric field and an enrichment in the optical\nspectra is found at low energy. The enrichment is attributed to the bandgap\nopening and increased energy spacing between the $\\pi{\\text -}\\pi^*$ bands. In\nBC$_{14}$N, the optical spectra are reduced due to the indirect bandgap or the\noverlapping of the $\\pi{\\text -}\\pi^* $ bands. Last, a high Seebeck coefficient\nis observed due to the presence of a direct bandgap in Si$_2$C$_{14}$, while it\nis not much enhanced in BC$_{14}$N."
    },
    {
        "anchor": "Nonlinear high-frequency hopping conduction in two-dimensional arrays of\n  Ge-in-Si quantum dots: Acoustic methods: Using acoustic methods we have measured nonlinear AC conductance in 2D arrays\nof Ge-in-Si quantum dots. The combination of experimental results and modeling\nof AC conductance of a dense lattice of localized states leads us to the\nconclusion that the main mechanism of AC conduction in hopping systems with\nlarge localization length is due to the charge transfer within large clusters,\nwhile the main mechanism behind its non-Ohmic behavior is charge heating by\nabsorbed power.",
        "positive": "Non-Hermitian Topological Theory of Finite-Lifetime Quasiparticles:\n  Prediction of Bulk Fermi Arc Due to Exceptional Point: We introduce a topological theory to study quasiparticles in interacting\nand/or disordered many-body systems, which have a finite lifetime due to\ninelastic and/or elastic scattering. The one-body quasiparticle Hamiltonian\nincludes both the Bloch Hamiltonian of band theory and the self-energy due to\ninteractions, which is non-Hermitian when quasiparticle lifetime is finite. We\nstudy the topology of non-Hermitian quasiparticle Hamiltonians in momentum\nspace, whose energy spectrum is complex. The interplay of band structure and\nquasiparticle lifetime is found to have remarkable consequences in zero- and\nsmall-gap systems. In particular, we predict the existence of topological\nexceptional point and bulk Fermi arc in Dirac materials with two distinct\nquasiparticle lifetimes."
    },
    {
        "anchor": "Surface plasmon polariton induced strong coherent superposition: A strong coherent superposition is shown to be induced between the energy\nstates of a two-level emitter immersed in a surface plasmon polariton\nevanescently confined to a small metallic ring. It turns out that there is\nnearly equal chance for the two-level emitter to be found either in the upper\nor lower energy level at steady state even for a weaker surface plasmon driving\nstrength. This indicates that it is possible to create a qubit that is robust\nagainst emitter spontaneous damping rate, which can be applicable in designing\na device that can perform certain quantum information processing tasks. In\nsupport of this proposal, the photon statistics of the emitted radiation is\nfound to exhibit significant nonclassical features.",
        "positive": "Density Modulations and Addition Spectra of Interacting Electrons in\n  Disordered Quantum Dots: We analyse the ground state of spinless fermions on a lattice in a weakly\ndisordered potential, interacting via a nearest neighbour interaction, by\napplying the self-consistent Hartree-Fock approximation. We find that charge\ndensity modulations emerge progressively when r_s >1, even away from\nhalf-filling, with only short-range density correlations. Classical geometry\ndependent \"magic numbers\" can show up in the addition spectrum which are\nremarkably robust against quantum fluctuations and disorder averaging."
    },
    {
        "anchor": "Transport Properties through Double Barrier Structure in Graphene: The mode-dependent transmission of relativistic ballistic massless Dirac\nfermion through a graphene based double barrier structure is being investigated\nfor various barrier parameters. We compare our results with already published\nwork and point out the relevance of these findings to a systematic study of the\ntransport properties in double barrier structures. An interesting situation\narises when we set the potential in the leads to zero, then our 2D problem\nreduces effectively to a 1D massive Dirac equation with an effective mass\nproportional to the quantized wave number along the transverse direction.\nFurthermore we have shown that the minimal conductivity and maximal Fano factor\nremain insensitive to the ratio between the two potentials V_2/V_1=\\alpha.",
        "positive": "Macroscopic 2D Wigner islands: In this paper we present new versatile \"2D macroscopic Wigner islands\" useful\nto investigate the various behaviors observed in mesoscopic confined systems.\nOur \"Wigner islands\" consist of electrostatically-interacting charged balls\nwith millimetric size. We have experimentally determined the ground\nconfigurations for systems of N particles (N=1-30) confined in a parabolic\npotential and checked the influence of the confinement and interacting\npotentials. The results obtained are compared with the published numerical\nresults."
    },
    {
        "anchor": "Electrically-tunable hole g-factor of an optically-active quantum dot\n  for fast spin rotations: We report a large g-factor tunability of a single hole spin in an InGaAs\nquantum dot via an electric field. The magnetic field lies in the in-plane\ndirection x, the direction required for a coherent hole spin. The electrical\nfield lies along the growth direction z and is changed over a large range, 100\nkV/cm. Both electron and hole g-factors are determined by high resolution laser\nspectroscopy with resonance fluorescence detection. This, along with the low\nelectrical-noise environment, gives very high quality experimental results. The\nhole g-factor g_xh depends linearly on the electric field Fz, dg_xh/dFz = (8.3\n+/- 1.2)* 10^-4 cm/kV, whereas the electron g-factor g_xe is independent of\nelectric field, dg_xe/dFz = (0.1 +/- 0.3)* 10^-4 cm/kV (results averaged over a\nnumber of quantum dots). The dependence of g_xh on Fz is well reproduced by a\n4x4 k.p model demonstrating that the electric field sensitivity arises from a\ncombination of soft hole confining potential, an In concentration gradient and\na strong dependence of material parameters on In concentration. The electric\nfield sensitivity of the hole spin can be exploited for electrically-driven\nhole spin rotations via the g-tensor modulation technique and based on these\nresults, a hole spin coupling as large as ~ 1 GHz is expected to be envisaged.",
        "positive": "Two-dimensional bipolar junction transistors: Recent development in fabrication technology of planar two-dimensional (2D)\nmaterials has brought up possibilities of numerous novel applications. Our\nrecent analysis has revealed that by definition of p-n junctions through\nappropriate patterned doping of 2D semiconductors, ideal exponential I-V\ncharacteristics may be expected. However, the theory of 2D junctions turns out\nto be very much different to that of the standard bulk junctions. Based on this\ntheory of 2D diodes, here we construct for the first time, a model to describe\nthe 2D Bipolar Junction Transistors (2D-BJTs). We derive the small-signal\nequivalent model, and estimate the performance of a 2D-BJT device based on\nGraphone as the example material. A current gain of about 138 and maximum\nthreshold frequency of 77GHz, together with a power-delay product of only 4fJ\nper 1um lateral width is expected at an operating voltage of 5V. Also, we\nderive necessary formulae and a new approximate solution for continuity\nequation in the 2D configuration, which have been verified against numerical\nsolutions."
    },
    {
        "anchor": "Interference effects induced by Andreev bound states in a hybrid\n  nanostructure composed by a quantum dot coupled to ferromagnetic and\n  superconductor leads: In this work, it is considered a nanostructure composed by a quantum dot\ncoupled to two ferromagnets and a superconductor. The transport properties of\nthis system are studied within a generalized mean-field approximation taking\ninto account proximity effects and spin-flip correlations within the quantum\ndot. It is shown that the zero-bias transmittance for the co-tunneling between\nthe ferromagnetic leads presents a dip whose height depends on the relative\norientation of the magnetizations. When the superconductor is coupled to the\nsystem, electron-hole correlations between different spin states leads to a\nresonance in the place of the dip appearing in the transmittance. Such an\neffect is accompanied by two anti-resonances explained by a leakage of\nconduction channels from the co-tunneling to the Andreev transport. In the\nnon-equilibrium regime, correlations within the quantum dot introduce a\ndependence of the resonance condition on the finite bias applied to the\nferromagnetic leads. However, it is still possible to observe signatures of the\nsame interference effect in the electrical current.",
        "positive": "Properties of magnetic nanodots with perpendicular anisotropy: Nanodots with magnetic vortices have many potential applications, such as\nmagnetic memories (VRAMs) and spin transfer nano-oscillators (STNOs). Adding a\nperpendicular anisotropy term to the magnetic energy of the nanodot it becomes\npossible to tune the vortex core properties. This can be obtained, e.g., in Co\nnanodots by varying the thickness of the Co layer in a Co/Pt stack. Here we\ndiscuss the spin configuration of circular and elliptical nanodots for\ndifferent perpendicular anisotropies; we show for nanodisks that micromagnetic\nsimulations and analytical results agree. Increasing the perpendicular\nanisotropy, the vortex core radii increase, the phase diagrams are modified and\nnew configurations appear; the knowledge of these phase diagrams is relevant\nfor the choice of optimum nanodot dimensions for applications. MFM measurements\non Co/Pt multilayers confirm the trend of the vortex core diameters with\nvarying Co layer thicknesses."
    },
    {
        "anchor": "Magnonic band structure of domain wall magnonic crystals: Magnonic crystals are prototype magnetic metamaterials designed for the\ncontrol of spin wave propagation. Conventional magnonic crystals are composed\nof single domain elements. If magnetization textures, such as domain walls,\nvortices and skyrmions, are included in the building blocks of magnonic\ncrystals, additional degrees of freedom over the control of the magnonic band\nstructure can be achieved. We theoretically investigate the influence of domain\nwalls on the spin wave propagation and the corresponding magnonic band\nstructure. It is found that the rotation of magnetization inside a domain wall\nintroduces a geometric vector potential for the spin wave excitation. The\ncorresponding Berry phase has quantized value $4 n_w \\pi$, where $n_w$ is the\nwinding number of the domain wall. Due to the topological vector potential, the\nmagnonic band structure of magnonic crystals with domain walls as comprising\nelements differs significantly from an identical magnonic crystal composed of\nonly magnetic domains. This difference can be utilized to realize dynamic\nreconfiguration of magnonic band structure by a sole nucleation or annihilation\nof domain walls in magnonic crystals.",
        "positive": "Sub-picosecond spin dynamics of excited states in the topological\n  insulator Bi$_2$Te$_3$: Using time-, spin- and angle-resolved photoemission, we investigate the\nultrafast spin dynamics of hot electrons on the surface of the topological\ninsulator Bi$_2$Te$_3$ following optical excitation by fs-infrared pulses. We\nobserve two surface-resonance states above the Fermi level coexisting with a\ntransient population of Dirac fermions that relax in about $\\sim$2 ps. One\nstate is located below $\\sim$0.4 eV just above the bulk continuum, the other\none at $\\sim$0.8 eV inside a projected bulk band gap. At the onset of the\nexcitation, both states exhibit a reversed spin texture with respect to that of\nthe transient Dirac bands, in agreement with our one-step photoemission\ncalculations. Our data reveal that the high-energy state undergoes spin\nrelaxation within $\\sim$0.5 ps, a process that triggers the subsequent spin\ndynamics of both the Dirac cone and the low-energy state, which behave as two\ndynamically-locked electron populations. We discuss the origin of this behavior\nby comparing the relaxation times observed for electrons with opposite spins to\nthe ones obtained from a microscopic Boltzmann model of ultrafast band cooling\nintroduced into the photoemission calculations. Our results demonstrate that\nthe nonequilibrium surface dynamics is governed by electron-electron rather\nthan electron-phonon scattering, with a characteristic time scale unambiguously\ndetermined by the complex spin texture of excited states above the Fermi level.\nOur findings reveal the critical importance of detecting momentum and\nenergy-resolved spin textures with fs resolution to fully understand the sub-ps\ndynamics of transient electrons on the surface of topological insulators."
    },
    {
        "anchor": "Chiral surface states on the step edge in a Weyl semimetal: A Weyl semimetal with a pair of Weyl nodes accommodates chiral states on its\nflat surface if the Weyl nodes are projected onto two different points in the\ncorresponding surface Brillouin zone. These surface states are collectively\nreferred to as a Fermi arc as they appear to connect the projected Weyl nodes.\nThis statement assumes that translational symmetry is present on the surface\nand hence electron momentum is a conserved quantity. It is unclear how chiral\nsurface states are modified if the translational symmetry is broken by a\nparticular system structure. Here, focusing on a straight step edge of finite\nwidth, we numerically analyze how chiral surface states appear on it. It is\nshown that the chiral surface states are algebraically (i.e., weakly) localized\nnear the step edge. It is also shown that the appearance of chiral surface\nstates is approximately determined by a simple condition characterized by the\nnumber of unit atomic layers constituting the step edge together with the\nlocation of the Weyl nodes.",
        "positive": "Observation of competing, correlated ground states in the flat band of\n  rhombohedral graphite: In crystalline solids the interactions of charge and spin can result in a\nvariety of emergent quantum ground states, especially in partially filled,\ntopological flat bands such as Landau levels or in 'magic-angle' bilayer\ngraphene. Much less explored is rhombohedral graphite (RG), perhaps the\nsimplest and structurally most perfect condensed matter system to host a flat\nband protected by symmetry. By scanning tunneling microscopy we map the flat\nband charge density of 8, 10 and 17 layers and identify a domain structure\nemerging from a competition between a sublattice antiferromagnetic insulator\nand a gapless correlated paramagnet. Our density-matrix renormalization group\ncalculations explain the observed features and demonstrate that the\ncorrelations are fundamentally different from graphene based magnetism\nidentified until now, forming the ground state of a quantum magnet. Our work\nestablishes RG as a new platform to study many-body interactions beyond the\nmean-field approach, where quantum fluctuations and entanglement dominate."
    },
    {
        "anchor": "Energy Relaxation of Hot Dirac Fermions in Graphene: We develop a theory for the energy relaxation of hot Dirac fermions in\ngraphene. We obtain a generic expression for the energy relaxation rate due to\nelectron-phonon interaction and calculate the power loss due to both optical\nand acoustic phonon emission as a function of electron temperature\n$T_{\\mathrm{e}}$ and density $n$. We find an intrinsic power loss weakly\ndependent on carrier density and non-vanishing at the Dirac point $n = 0$,\noriginating from interband electron-optical phonon scattering by the intrinsic\nelectrons in the graphene valence band. We obtain the total power loss per\ncarrier $\\sim 10^{-12} - 10^{-7} \\mathrm{W}$ within the range of electron\ntemperatures $\\sim 20 - 1000 \\mathrm{K}$. We find optical (acoustic) phonon\nemission to dominate the energy loss for $T_{\\mathrm{e}} > (<) 200-300\n\\mathrm{K}$ in the density range $n = 10^{11}-10^{13} \\mathrm{cm}^{-2}$.",
        "positive": "Electron transport in a slot-gate Si MOSFET: The transversal and longitudinal resistance in the quantum Hall effect regime\nwas measured in a Si MOSFET sample in which a slot-gate allows one to vary the\nelectron density and filling factor in different parts of the sample. In case\nof unequal gate voltages, the longitudinal resistances on the opposite sides of\nthe sample differ from each other because the originated Hall voltage\ndifference is added to the longitudinal voltage only on one side depending on\nthe gradient of the gate voltages and the direction of the external magnetic\nfield. After subtracting the Hall voltage difference, the increase in\nlongitudinal resistance is observed when electrons on the opposite sides of the\nslot occupy Landau levels with different spin orientations."
    },
    {
        "anchor": "Kondo effect in complex mesoscopic structures: We study the Kondo effect of a quantum dot placed in a complex mesoscopic\nstructure. Assuming that electronic interactions are taking place solely on the\ndot, and focusing on the infinite Hubbard interaction limit, we use a\ndecoupling scheme to obtain an explicit analytic approximate expression for the\ndot Green function, which fulfills certain Fermi-liquid relations at zero\ntemperature. The details of the complex structure enter into this expression\nonly via the self-energy for the non-interacting case. The effectiveness of the\nexpression is demonstrated for the single impurity Anderson model and for the\nT-shaped network.",
        "positive": "Optical-Cavity-Induced Current: The formation of a submicron optical cavity on one side of a\nmetal-insulator-metal (MIM) tunneling device induces a measurable electrical\ncurrent between the two metal layers with no applied voltage. Reducing the\ncavity thickness increases the measured current. Eight types of tests were\ncarried out to determine whether the output could be due to experimental\nartifacts. All gave negative results, supporting the conclusion that the\nobserved electrical output is genuinely produced by the device. We interpret\nthe results as being due to the suppression of vacuum optical modes by the\noptical cavity on one side of the MIM device, which upsets a balance in the\ninjection of electrons excited by zero-point fluctuations. This interpretation\nis in accord with observed changes in electrical output as other device\nparameters are varied. A feature of the MIM devices is their femtosecond-fast\ntransport and scattering times for hot charge carriers. The fast capture in\nthese devices is consistent with a model in which an energy {\\Delta}E may be\naccessed from zero-point fluctuations for a time {\\Delta}t, following a\n{\\Delta}E{\\Delta}t uncertainty-principle-like relation governing the process."
    },
    {
        "anchor": "Engineering drag currents in Coulomb coupled quantum dots: The Coulomb drag phenomenon in a Coulomb-coupled double quantum dot system is\nrevisited with a simple model that highlights the importance of simultaneous\ntunneling of electrons. Previously, cotunneling effects on the drag current in\nmesoscopic setups have been reported both theoretically and experimentally.\nHowever, in both cases the sequential tunneling contribution to the drag\ncurrent was always present unless the drag level position were too far away\nfrom resonance. Here, we consider the case of very large Coulomb interaction\nbetween the dots, whereby the drag current needs to be assisted by cotunneling\nevents. As a consequence, a quantum coherent drag effect takes place. Further,\nwe demonstrate that by properly engineering the tunneling probabilities using\nband tailoring it is possible to control the sign of the drag and drive\ncurrents, allowing them to flow in parallel or antiparallel directions. We also\nshow that the drag current can be manipulated by varying the drag gate\npotential and is thus governed by electron- or hole-like transport.",
        "positive": "A four-qubit germanium quantum processor: The prospect of building quantum circuits using advanced semiconductor\nmanufacturing positions quantum dots as an attractive platform for quantum\ninformation processing. Extensive studies on various materials have led to\ndemonstrations of two-qubit logic in gallium arsenide, silicon, and germanium.\nHowever, interconnecting larger numbers of qubits in semiconductor devices has\nremained an outstanding challenge. Here, we demonstrate a four-qubit quantum\nprocessor based on hole spins in germanium quantum dots. Furthermore, we define\nthe quantum dots in a two-by-two array and obtain controllable coupling along\nboth directions. Qubit logic is implemented all-electrically and the exchange\ninteraction can be pulsed to freely program one-qubit, two-qubit, three-qubit,\nand four-qubit operations, resulting in a compact and high-connectivity\ncircuit. We execute a quantum logic circuit that generates a four-qubit\nGreenberger-Horne-Zeilinger state and we obtain coherent evolution by\nincorporating dynamical decoupling. These results are an important step towards\nquantum error correction and quantum simulation with quantum dots."
    },
    {
        "anchor": "Astronomical chemical evolution from graphene to polycyclic aromatic\n  hydrocarbon reproducing observed infrared spectrum: Interstellar ubiquitous infrared spectrum (IR) due to polycyclic aromatic\nhydrocarbon (PAH) was observed in many astronomical dust clouds. A capable\nastronomical chemical evolution path from graphene to PAH was studied based on\nthe first principles calculation. Step 1 is a nucleation of nano-carbon after\nsupernova by super-cooling at expanding helium sphere. As a typical model,\ngraphene molecule (C )24 having coronene skeleton with seven carbon hexagons\nwas tried.Step 2 is a proton sputtering and passivation on ejected graphene\nmolecule. Slow speed proton with energy less than 4.3eV makes hydrogenation,\nGraphene molecule (C )24 was transformed to PAH (C24H12). Higher speed proton\nhaving sufficient energy larger than 18.3 eV could make a void in a molecule as\nlike C23H12. Resulted structure was a combination of two carbon pentagons and\nfive hexagons. Step 3 is photo-ionization of those molecules by high energy\nphoton. Electrons are removed to make a molecule to cation. Model molecule\n(C23H12) became mono-cation (C23H12)+, di-cation (C23H12)2+ and so on. Typical\nenergy difference between such cation was 6.5 and 10.8 eV. If the light source\nhas a nature of black-body radiation, effective temperature will be 18000K ~\n24000K, which suggested that central light source star may have 4 to 7 times\nheavier than our sun. Finally, theoretical IR spectrum was obtained. Especially\nin case of (C23H12)2+, calculated emission spectrum revealed that among 13\nmajor peaks, 11 peaks could correlate with ubiquitous observed IR one.",
        "positive": "Probing a spin transfer controlled magnetic nanowire with a single\n  nitrogen-vacancy spin in bulk diamond: The point-like nature and exquisite magnetic field sensitivity of the\nnitrogen vacancy (NV) center in diamond can provide information about the inner\nworkings of magnetic nanocircuits in complement with traditional transport\ntechniques. Here we use a single NV in bulk diamond to probe the stray field of\na ferromagnetic nanowire controlled by spin transfer (ST) torques. We first\nreport an unambiguous measurement of ST tuned, parametrically driven,\nlarge-amplitude magnetic oscillations. At the same time, we demonstrate that\nsuch magnetic oscillations alone can directly drive NV spin transitions,\nproviding a potential new means of control. Finally, we use the NV as a local\nnoise thermometer, observing strong ST damping of the stray field noise,\nconsistent with magnetic cooling from room temperature to $\\sim$150 K."
    },
    {
        "anchor": "Boosting the Edelstein effect of two-dimensional electron gases by\n  ferromagnetic exchange: Strontium titanate (SrTiO$_3$) two-dimensional electron gases (2DEGs) have\nbroken spatial inversion symmetry and possess a finite Rashba spin-orbit\ncoupling. This enables the interconversion of charge and spin currents through\nthe direct and inverse Edelstein effects, with record efficiencies at low\ntemperature, but more modest effects at room temperature. Here, we show that\nmaking these 2DEGs ferromagnetic enhances the conversion efficiency by nearly\none order of magnitude. Starting from the experimental band structure of\nnon-magnetic SrTiO$_3$ 2DEGs, we mimic magnetic exchange coupling by\nintroducing an out-of-plane Zeeman term in a tight-binding model. We then\ncalculate the band structure and spin textures for increasing internal magnetic\nfields and compute the Edelstein effect using a semiclassical Boltzmann\napproach. We find that the conversion efficiency first increases strongly with\nincreasing magnetic field, then shows a maximum and finally decreases. This\nfield dependence is caused by the competition of the exchange coupling with the\neffective Rashba interaction. While enhancing the splitting of band pairs\namplifies the Edelstein effect, weakening the in-plane Rashba-type spin texture\nreduces it.",
        "positive": "CdSe-Au nanorod networks welded by gold domains - a promising structure\n  for nano-optoelectronic components: CdSe-Au networks were synthesized by a colloidal chemistry technique. They\nentail CdSe nanorods with a diameter of ~10 nm and a length of ~40 nm, which\nare joined together by Au domains (~5 nm). Individual networks were positioned\nby AC dielectrophoresis between bow-tie electrodes with a gap of ~100 nm and\ntheir conductivity as well as the photoelectrical properties were investigated.\nNanorod networks, with multiple Au domains on the nanorod surface, displayed\nstable conductivity that was not sensitive to blue laser light illumination.\nSuch nanostructures were transformed by thermal annealing to networks with Au\ndomains only at the nanorod tips. In this system the overall conductivity was\nreduced, but a clear photocurrent signal could be detected, manifesting\nsemiconductor behavior."
    },
    {
        "anchor": "Transport in a one-dimensional Luttinger liquid: In this paper we review recent theoretical results for transport in a\none-dimensional (1d) Luttinger liquid. For simplicity, we ignore electron spin,\nand focus exclusively on the case of a single-mode. Moreover, we consider only\nthe effects of a single (or perhaps several) spatially localized impurities.\nEven with these restrictions, the predicted behavior is very rich, and\nstrikingly different than for a 1d non-interacting electron gas. The method of\nbosonization is reviewed, with an emphasis on physical motivation, rather than\nmathematical rigor. Transport through a single impurity is reviewed from\nseveral different perspectives, as a pinned strongly interacting ``Wigner\"\ncrystal and in the limit of weak interactions. The existence of fractionally\ncharged quasiparticles is also revealed. Inter-edge tunnelling in the quantum\nHall effect, and charge fluctuations in a quantum dot under the conditions of\nCoulomb blockade are considered as examples of the developed techniques.",
        "positive": "Chiral second-sound collective mode at the edge of 2D systems with\n  nontrivial Berry curvature: We study the thermal transport in two-dimensional systems with a nontrivial\nBerry curvature texture. The physical realizations are many: for a sake of\ndefiniteness we consider undoped graphene gapped by the presence of an aligned\nhexagonal-Boron-Nitride substrate. The same phenomenology applies, i.e., to\nsurface states of 3D topological insulators in the presence of a uniform\nmagnetization. We find that chiral valley-polarized second-sound collective\nmodes propagate along the edges of the system. The localization length of the\nedge modes has topological origin stemming from the anomalous velocity term in\nthe quasiparticle current. At low temperature, the single-particle contribution\nto the transverse thermal conductance is exponentially suppressed and only\nsecond-sound modes carry heat along the boundary. A sharp change in the\nbehavior of the thermal Hall conductance, extracted from nonlocal measurements\nof the temperature along the edge, marks the onset of ballistic heat transport\ndue to second-sound edge modes."
    },
    {
        "anchor": "Josephson effect in a few-hole quantum dot: We use a Ge-Si core-shell nanowire to realise a Josephson field-effect\ntransistor with highly transparent contacts to superconducting leads. By\nchanging the electric field we gain access to two distinct regimes not combined\nbefore in a single device: In the accumulation mode the device is highly\ntransparent and the supercurrent is carried by multiple subbands, while near\ndepletion supercurrent is carried by single-particle levels of a strongly\ncoupled quantum dot operating in the few-hole regime. These results establish\nGe-Si nanowires as an important platform for hybrid\nsuperconductor-semiconductor physics and Majorana fermions.",
        "positive": "Nonlinear response and two stable electrical conductivity levels\n  measured in plasticized PVC thin film samples: The electrical conductivity of PVC films prepared with a patented plasticizer\nof type \"A\" was measured with high precision automated setup, based on standard\nring sell with a voltage range much less than breakdown voltage. Continual\nvoltage-current measurements permit to take into account Debay relaxation\nprocess and clearly distinguish specific polymer film conductivity effects,\nconnected with continuous current-stabilization behavior and transitions\nbetween two stable (long-living) states with several order magnitude different\nconductivities. Spontaneous reversible and non-destructive transitions of\nresistance levels was observed. For 30 mkm polymer films the values of sample\nresistance was measured equal to: high- 106 Ohm and low -103 Ohm."
    },
    {
        "anchor": "Thermal Gating of Charge Currents with Coulomb Coupled Quantum Dots: We have observed thermal gating, i.e. electrostatic gating induced by hot\nelectrons. The effect occurs in a device consisting of two capacitively coupled\nquantum dots. The double dot system is coupled to a hot electron reservoir on\none side (QD1), whilst the conductance of the second dot (QD2) is monitored.\nWhen a bias across QD2 is applied we observe a current which is strongly\ndependent on the temperature of the heat reservoir. This current can be either\nenhanced or suppressed, depending on the relative energetic alignment of the QD\nlevels. Thus, the system can be used to control a charge current by hot\nelectrons.",
        "positive": "Raman spectra of nanoparticles: elasticity theory-like approach for\n  optical phonons: A simple way to investigate theoretically the Raman spectra (RS) of nonpolar\nnanoparticles is proposed. For this aim we substitute the original lattice\noptical phonon eigenproblem by the continuous Klein-Fock-Gordon-like equation\nwith Dirichlet boundary conditions. This approach provides the basis for the\ncontinuous description of optical phonons in the same manner how the elasticity\ntheory describes the longwavelength acoustic phonons. Together with continuous\nreformulation of the bond polarization model it allows to calculate the RS of\nnanoparticles without referring to their atomistic structure. It ensures the\npowerful tool for interpreting the experimental data, studying the effects of\nparticle shape and their size distribution. We successfully fit recent\nexperimental data on very small diamond and silicon particles, for which the\ncommonly used phonon confinement model fails. The predictions of our theory are\ncompared with recent results obtained within the dynamical matrix method - bond\npolarization model (DMM-BPM) approach and an excellent agreement between them\nis found. The advantages of the present theory are its simplicity and the\nrapidity of calculations. We analyze how the RS are affected by the\nnanoparticle faceting and propose a simple power law for Raman peak position\ndependence on the facets number. The method of powder RS calculations is\nformulated and the limitations on the accuracy of our analysis are discussed."
    },
    {
        "anchor": "Chiral Domain Wall Injector Driven by Spin-orbit Torques: Memory and logic devices that encode information in magnetic domains rely on\nthe controlled injection of domain walls to reach their full potential. In this\nwork, we exploit the chiral coupling induced by the Dzyaloshinskii-Moriya\ninteraction between in-plane and out-of-plane magnetized regions of a\nPt/Co/AlO\\textsubscript{x} trilayer in combination with current-driven\nspin-orbit torques to control the injection of domain walls into magnetic\nconduits. We demonstrate that the current-induced domain nucleation is strongly\ninhibited for magnetic configurations stabilized by the chiral coupling and\npromoted for those that have the opposite chirality. These configurations allow\nfor efficient domain wall injection using current densities of the order of\n$4\\times$\\SI{e11}{A m^{-2}}, which are lower than those used in other injection\nschemes. Furthermore, by setting the orientation of the in-plane magnetization\nusing an external field, we demonstrate the use of a chiral domain wall\ninjector to create a controlled sequence of alternating domains in a racetrack\nstructure driven by a steady stream of unipolar current pulses.",
        "positive": "Transfer of entanglement from electrons to photons by optical selection\n  rules: The entanglement transfer from electrons localized in a pair of quantum dots\nto circularly polarized photons is governed by optical selection rules,\nenforced by conservation of angular momentum. We point out that the transfer\ncan not be achieved by means of unitary evolution unless the angular momentum\nof the two initial qubit states differs by 2 units. In particular, for\nspin-entangled electrons the difference in angular momentum is 1 unit -- so the\ntransfer fails. Nevertheless, the transfer can be successfully completed if the\nunitary evolution is followed by a measurement of the angular momentum of each\nquantum dot and post-processing of the photons using the measured values as\ninput."
    },
    {
        "anchor": "Electronic superlattices in corrugated graphene: We theoretically investigate electron transport through corrugated graphene\nribbons and show how the ribbon curvature leads to an electronic superlattice\nwith a period set by the corrugation wave length. Transport through the ribbon\ndepends sensitively on the superlattice band structure which, in turn, strongly\ndepends on the geometry of the deformed sheet. In particular, we find that for\nribbon widths where the transverse level separation is comparable to the the\nband edge energy, a strong current switching occurs as function of an applied\nbackgate voltage. Thus, artificially corrugated graphene sheets or ribbons can\nbe used for the study of Dirac fermions in periodic potentials. Furthermore,\nthis provides an additional design paradigm for graphene-based electronics.",
        "positive": "Dynamic Magnetoelastic Boundary Conditions and the Pumping of Phonons: We derive boundary conditions at the interfaces of magnetoelastic\nheterostructures under ferromagnetic resonance for arbitrary magnetization\ndirections and interface shapes. We apply our formalism to\nmagnet$\\vert$nonmagnet bilayers and magnetic grains embedded in a nonmagnetic\nthin film, revealing a nontrivial magnetization angle dependence of acoustic\nphonon pumping."
    },
    {
        "anchor": "Distinct quasiparticle interference patterns for surface impurity\n  scattering on various Weyl semimetals: We examine the response of the Fermi arc in the context of quasi-particle\ninterference (QPI) with regard to a localized surface impurity on various\nthree-dimensional Weyl semimetals (WSMs). Our study also reveals the variation\nof the local density of states (LDOS), obtained by Fourier transforming the QPI\nprofile, on the two-dimensional surface. We use the $T$-matrix formalism to\nnumerically (analytically and numerically) capture the details of the momentum\nspace scattering in QPI (real space decay in LDOS), considering relevant\ntight-binding lattice and/or low-energy continuum models modeling a range of\ndifferent WSMs. In particular, we consider multi-WSM (mWSM), hosting multiple\nFermi arcs between two opposite chirality Weyl nodes (WNs), where we find a\nuniversal $1/r$-decay ($r$ measuring the radial distance from the impurity\ncore) of the impurity-induced LDOS, irrespective of the topological charge.\nInterestingly, the inter-Fermi arc scattering is only present for triple WSMs,\nwhere we find an additional $1/r^3$-decay as compared to double and single\nWSMs. The untilted single (double) [triple] WSM shows a straight-line\n(leaf-like) [oval-shaped] QPI profile. The above QPI profiles are canted for\nhybrid WSMs where type-I and type-II Weyl nodes coexist, however, hybrid single\nWSM demonstrates strong non-uniformity, unlike the hybrid double and triple\nWSMs. We also show that the chirality and the positions of the Weyl nodes\nimprint marked signatures in the QPI profile. This allows us to distinguish\nbetween different WSMs, including the time-reversal-broken WSMs from the\ntime-reversal-invariant WSM, even though both of the WSMs can host two pairs of\nWeyl nodes. Our study can thus shed light on experimentally obtainable complex\nQPI profiles and help differentiate different WSMs and their surface band\nstructures.",
        "positive": "Spin-dynamic field coupling in strongly THz driven semiconductors :\n  local inversion symmetry breaking: We study theoretically the optics in undoped direct gap semiconductors which\nare strongly driven in the THz regime. We calculate the optical sideband\ngeneration due to nonlinear mixing of the THz field and the near infrared\nprobe. Starting with an inversion symmetric microscopic Hamiltonian we include\nthe THz field nonperturbatively using non-equilibrium Green function\ntechniques. We find that a self induced relativistic spin-THz field coupling\nlocally breaks the inversion symmetry, resulting in the formation of odd\nsidebands which otherwise are absent."
    },
    {
        "anchor": "Analog Circuit Applications based on Ambipolar Graphene/MoTe2 Vertical\n  Transistors: The current integrated circuit (IC) technology based on conventional MOS-FET\n(metal-oxide-semiconductor field-effect transistor) is approaching the limit of\nminiaturization with increasing demand on energy. Several analog circuit\napplications based on graphene FETs have been demonstrated with less components\ncomparing to the conventional technology. However, low on/off current ratio\ncaused by the semimetal nature of graphene has severely hindered its practical\napplications. Here we report a graphene/MoTe2 van der Waals (vdW) vertical\ntransistor with V-shaped ambipolar field effect transfer characteristics to\novercome this challenge. Investigations on temperature dependence of transport\nproperties reveal that gate tunable asymmetric barriers of the devices are\naccount for the ambipolar behaviors. Furthermore, to demonstrate the analog\ncircuit applications of such vdW vertical transistors, we successfully realized\noutput polarity controllable (OPC) amplifier and frequency doubler. These\nresults enable vdW heterojunction based electronic devices to open up new\npossibilities for wide perspective in telecommunication field.",
        "positive": "Time-resolved ARPES with probe energy of 6.0/7.2 eV and switchable\n  resolution configuration: We present a detailed exposition of the design for time- and angle-resolved\nphotoemission spectroscopy using a UV probe laser source that combines the\nnonlinear effects of \\b{eta}-BaB2O4 and KBe2BO3F2 optical crystals. The photon\nenergy of the probe laser can be switched between 6.0 and 7.2 eV, with the\nflexibility to operate each photon energy setting under two distinct resolution\nconfigurations. Under the fully optimized energy resolution configuration, we\nachieve an energy resolution of 8.5 meV at 6.0 eV and 10 meV at 7.2 eV.\nAlternatively, switching to the other configuration enhances temporal\nresolution, yielding a temporal resolution of 72 fs for 6.0 eV and 185 fs for\n7.2 eV. We validated the performance and reliability of our system by applying\nit to measuring two typical materials: the topological insulator MnBi2Te4 and\nexcitonic insulator candidate Ta2NiSe5."
    },
    {
        "anchor": "Shot noise in semiclassical chaotic cavities: We construct a trajectory-based semiclassical theory of shot noise in clean\nchaotic cavities. In the universal regime of vanishing Ehrenfest time $\\tE$, we\nreproduce the random matrix theory result, and show that the Fano factor is\nexponentially suppressed as $\\tE$ increases. We demonstrate how our theory\npreserves the unitarity of the scattering matrix even in the regime of finite\n$\\tE$. We discuss the range of validity of our semiclassical approach and point\nout subtleties relevant to the recent semiclassical treatment of shot noise in\nthe universal regime by Braun et al. [cond-mat/0511292].",
        "positive": "Superconducting pi qubit with three Josephson junctions: We propose a new qubit consisting of a superconducting ring with two ordinary\nzero junctions and one ferromagnetic pi junction. In the system, two degenerate\nstable states appear in the phase space without an external magnetic field\nbecause of a competition between the zero and pi states. Quantum tunneling\nbetween the two degenerate states leads to a formation of bonding and\nantibonding states (coherent states) which are used as a bit. For manipulating\nthe states of the qubit, only small external magnetic field around zero is\nrequired. This feature leads to a large-scale integration and a construction of\nthe qubit with a smaller size which is robust to the decoherence by external\nnoises."
    },
    {
        "anchor": "Controllable p$-$n junctions in three$-$dimensional Dirac semimetal\n  Cd$_3$As$_2$ nanowires: We demonstrate a controllable p$-$n junction in a three$-$dimensional Dirac\nsemimetal (DSM) Cd$_3$As$_2$ nanowire with two recessed bottom gates. The\ndevice exhibits four different conductance regimes with gate voltages, the\nunipolar (n$-$n and p$-$p) regime and the bipolar (n$-$p and n$-$p) one, where\np$-$n junctions are formed. The conductance in the p$-$n junction regime\ndecreases drastically when a magnetic field is applied perpendicular to the\nnanowire, which is due to the suppression of Klein tunneling. In this regime,\nthe device shows quantum dot behavior. On the other hand, clear conductance\nplateaus are observed in the n$-$n regime likely owing to the cyclotron motion\nof carriers at high magnetic fields. Our experiment shows that the ambipolar\ntunability of DSM nanowires can enable the realization of quantum devices based\non quantum dots and electron optics.",
        "positive": "Spin transport and dynamic properties of two-dimensional spin-momentum\n  locked states: Materials with spin-momentum locked surface or interface states provide an\ninteresting playground for studying physics and application of charge-spin\ncurrent conversion. To characterize their non-equilibrium magnetic and\ntransport properties in the presence of a time-dependent external magnetic\nfield and a spin injection from a contact, we introduce three macroscopic\nvariables: a vectorial helical magnetization, a scaler helical magnetization,\nand the conventional magnetization. We derive a set of closed dynamic equations\nfor these variables by using the spinor Boltzmann approach with the collision\nterms consistent with the symmetry of spin-momentum locked states. By solving\nthe dynamic equations, we predict several intriguing magnetic and transport\nphenomena which are experimentally accessible, including magnetic resonant\nresponse to an AC applied magnetic field, charge-spin conversion, and spin\ncurrent induced by the dynamics of helical magnetization."
    },
    {
        "anchor": "Numerical Renormalization Group Analysis of Interacting Quantum Dots: Wilson's Numerical Renormalization Group (NRG) is so far the only\nnonperturbative technique that can reliably access low-energy properties of\nquantum impurity systems. We present a recent extension of the method, the\nDM-NRG, which yields highly accurate results for dynamical quantities at\narbitrary frequencies and temperatures. As an application, we determine the\nspectrum of a quantum dot in an external magnetic field. Furthermore, we\ndiscuss magnetic impurities with orbital degeneracy, which have been inferred\nin recent experiments on quantum dots in an Aharonov-Bohm geometry. It is\ndemonstrated that for spinless electrons, interference between neighbouring\nlevels sets the low-energy scale of the system. Switching on an external field\nleads to a remarkable crossover into a regime dominated by orbital Kondo\nscreening. We predict that the broadening-induced level splitting should be\nclearly visible in measurements of the optical absorption power. A more general\nmodel including the electron spin is studied within an extended two-band NRG\nprocedure. We observe competition between interference and Kondo screening,\nsimilar to the situation in two-impurity models (RKKY).",
        "positive": "Semiclassical theory of nonlinear magneto-optical responses with\n  applications to topological Dirac/Weyl semimetals: We study nonlinear magneto-optical responses of metals by a semiclassical\nBoltzmann equation approach. We derive general formulas for linear and second\norder nonlinear optical effects in the presence of magnetic fields that include\nboth Berry curvature and orbital magnetic moment. Applied to Weyl fermions, the\nsemiclassical approach (i) captures the directional anisotropy of linear\nconductivity under magnetic field as a consequence of an anisotropic $B^2$\ncontribution, which may explain the low-field regime of recent experiments;\n(ii) predicts strong second harmonic generation proportional to $B$ that is\nenhanced as the Fermi energy approaches the Weyl point, leading to large\nnonlinear Kerr rotation. Moreover, we show that the semiclassical formula for\nthe circular photogalvanic effect arising from the Berry curvature dipole is\nreproduced by a full quantum calculation using a Floquet approach."
    },
    {
        "anchor": "Near-field cavity optomechanical coupling in a compound semiconductor\n  nanowire: A III-V compound semiconductor nanowire is an attractive material for a novel\nhybrid quantum interface that interconnects photons, electrons, and phonons\nthrough a wavelength-tunable quantum structure embedded in its free-standing\nstructure. In such a nanomechanical element, however, a challenge is how to\ndetect and manipulate a small number of phonons via its tiny mechanical motion.\nA solution would be to couple an optical cavity to a nanowire by introducing\nthe ``cavity optomechanics'' framework, but the typical size difference between\nthem becomes a barrier to achieving this. Here, we demonstrate near-field\ncoupling of a silica microsphere cavity and an epitaxially grown InP/InAs\nfree-standing nanowire. The evanescent optomechanical coupling enables not only\nfine probing of the mechanical motion by balanced homodyne interferometry but\nalso tuning of the resonance frequency, linewidth, Duffing nonlinearity, and\nvibration axis in the nanowire. Combining this cavity optomechanics with\nepitaxial nanowire engineering opens the way to novel quantum metrology and\ninformation processing.",
        "positive": "Ag adatoms on Si(111)5x2-Au surface: Using scanning tunneling microscopy together with the first-principles\ndensity functional theory calculations we study structural properties of the\nSi(111)5x2-Au surface covered by Ag adatoms. The STM topography data show that\na submonolayer coverage of Ag does not lead to a well-ordered adatom chain\nstructure with a periodicity 5x4, as it was observed for Si, Pb and In adatoms.\nInstead of that, we observe Ag adatoms located in different nonequivalent\npositions within the unit cell, which confirms the electronic nature of\nstabilization of the Si(111)5x2-Au surface. Moreover, the DFT calculations give\nfive different structural models of the Si(111)5x2-Au/Ag surface. All the\nmodels are almost degenerate in energy, which further supports the above\nscenario."
    },
    {
        "anchor": "Spin Transport in non-inertial frame: The influence of acceleration and rotation on spintronic applications is\ntheoretically investigated. In our formulation, considering a Dirac particle in\na non-inertial frame, different spin related aspects are studied. The spin\ncurrent appearing due to the inertial spin-orbit coupling (SOC) is enhanced by\nthe interband mixing of the conduction and valence band states. Importantly,\none can achieve a large spin current through the $\\vec{k}. \\vec{p}$ method in\nthis non-inertial frame. Furthermore, apart from the inertial SOC term due to\nacceleration, for a particular choice of the rotation frequency, a new kind of\nSOC term can be obtained from the spin rotation coupling (SRC). This new kind\nof SOC is of Dresselhaus type and controllable through the rotation frequency.\nIn the field of spintronic applications, utilizing the inertial SOC and SRC\ninduced SOC term, theoretical proposals for the inertial spin filter, inertial\nspin galvanic effect are demonstrated. Finally, one can tune the spin\nrelaxation time in semiconductors by tuning the non-inertial parameters.",
        "positive": "Decoherence in a Cooper pair shuttle: We examine decoherence effects in the Josephson current of a Cooper pair\nshuttle. Dephasing due to gate voltage fluctuations can either suppress or\nenhance the critical current and also change its sign. The current noise\nspectrum displays a peak at the Josephson coupling energy and shows a phase\ndependence."
    },
    {
        "anchor": "Time-dependent Transport in arbitrary extended driven tunnel junctions: We develop a very general perturbative theory of time-dependent transport in\na weak tunneling junction which is independent of experimental details and on\nmany-body correlated states in the coupled conductors. These can be similar or\ndifferent, with arbitrary internal or mutual interactions, superconducting\ncorrelations, disorder, and coupled to an electromagnetic environment or other\nquantum systems. The junction can be spatially extended, and is subject,\nsimultaneously, to time-dependent voltage, local magnetic field and modulation\nof the tunneling amplitudes. All observables at arbitrary frequencies: average\ncurrent, non-equilibrium admittance and current correlations can be expressed\nin a universal way through the out-of-equilibrium DC current only, yielding\nperturbative time-dependent non-equilibrium fluctuation relations. In\nparticular, charge fluctuations are shown to be universally super-poissonian,\nand to become poissonian if the junction is driven by a series of Lorentzian\npulses. We also generalize, for constant voltage and tunneling, the poissonian\nshot noise and the fluctuation relation between the derivatives of the noise\nand the conductance. Thus we provide a compact, general and transparent\nunifying theory at arbitrary dimension, in contrast with involved derivations\nbased explicitly on particular models and profiles of a single time-varying\nfield.",
        "positive": "Magnetic energy of sc ferromagnetic films with three layers as described\n  by third order perturbed Heisenberg Hamiltonian: The solution of third order perturbed Heisenberg Hamiltonian of simple cubic\nferromagnetic ultra-thin films with three layers were found. All the magnetic\nenergy parameters such as spin exchange interaction, magnetic dipole\ninteraction, second order magnetic anisotropy, fourth order magnetic\nanisotropy, applied magnetic field, demagnetization factor and stress induced\nanisotropy were included in the third order perturbed Heisenberg Hamiltonian.\n3-D plots of stress induced anisotropy, out of plane magnetic field,\ndemagnetization factor and spin exchange interaction are presented in this\nmanuscript. Magnetic easy and hard directions were determined using these 3-D\nplots. MATLAB program was employed to solve the equation with seven parameters."
    },
    {
        "anchor": "Evidence for a Monolayer Excitonic Insulator: The interplay between topology and correlations can generate a variety of\nquantum phases, many of which remain to be explored. Recent advances have\nidentified monolayer WTe2 as a promising material for doing so in a highly\ntunable fashion. The ground state of this two-dimensional (2D) crystal can be\nelectrostatically tuned from a quantum spin Hall insulator (QSHI) to a\nsuperconductor. However, much remains unknown about the gap-opening mechanism\nof the insulating state. Here we report evidence that the QSHI is also an\nexcitonic insulator (EI), arising from the spontaneous formation of\nelectron-hole bound states (excitons). We reveal the presence of an intrinsic\ninsulating state at the charge neutrality point (CNP) in clean samples and\nconfirm the correlated nature of this charge-neutral insulator by tunneling\nspectroscopy. We provide evidence against alternative scenarios of a band\ninsulator or a localized insulator and support the existence of an EI phase in\nthe clean limit. These observations lay the foundation for understanding a new\nclass of correlated insulators with nontrivial topology and identify monolayer\nWTe2 as a promising candidate for exploring quantum phases of ground-state\nexcitons.",
        "positive": "Metallic Nanosphere in a Magnetic Field: an Exact Solution: We consider the electron gas moving on the surface of a sphere in a uniform\nmagnetic field. An exact solution of the problem is found in terms of oblate\nspheroidal functions, depending on the parameter $p= \\Phi/\\Phi_0$, the number\nof flux quanta piercing the sphere. The regimes of weak and strong fields are\ndiscussed, the Green's functions are found for both limiting cases in the\nclosed form. In the weak fields the magnetic susceptibility reveals a set of\njumps at half-integer $p$. The strong field regime is characterized by the\nformation of Landau levels and localization of the electron states near the\npoles of the sphere defined by a direction of the field. The effects of\ncoherence within the sphere are lost when its radius exceeds the mean-free\npath."
    },
    {
        "anchor": "An Investigation of Orientational Symmetry-Breaking Mechanisms in High\n  Landau Levels: The principal axes of the recently discovered anisotropic phases of 2D\nelectron systems at high Landau level occupancy are consistently oriented\nrelative to the crystal axes of the host semiconductor. The nature of the\nnative rotational symmetry breaking field responsible for this preferential\norientation remains unknown. Here we report on experiments designed to\ninvestigate the origin and magnitude of this symmetry breaking field. Our\nresults suggest that neither micron-scale surface roughness features nor the\nprecise symmetry of the quantum well potential confining the 2D system are\nimportant factors. By combining tilted field transport measurements with\ndetailed self-consistent calculations we estimate that the native anisotropy\nenergy, whatever its origin, is typically ~ 1 mK per electron.",
        "positive": "Nonlinear behavior and mode coupling in spin transfer nano-oscillators: By investigating thoroughly the tunable behavior of coupled modes, we\nhighlight how it provides new means to handle the properties of spin transfer\nnano-oscillators. We first demonstrate that the main features of the microwave\nsignal associated with coupled vortex dynamics i.e. frequency, spectral\ncoherence, critical current, mode localization, depends drastically on the\nrelative vortex core polarities. Secondly we report a large reduction of the\nnonlinear linewidth broadening obtained by changing the effective damping\nthrough the control of the core configuration. Such a level of control on the\nnonlinear behavior reinforces our choice to exploit the microwave properties of\ncollective modes for applications of spintronic devices in novel generation of\nintegrated telecommunication devices."
    },
    {
        "anchor": "Size Dependence in Multicolor Upconversion in Single Yb3+, Er3+ Co-doped\n  NaYF4 Nanocrystals: Schietinger et al. (Nano Lett. 2009, 9, 2477-2481) observed single\nnanoparticle emission from NaYF4:Er3+,Yb3+ and noted unusual changes in the\nintensities of red and green emissions with particle size. We show that the\ndocumented changes are due to instrumental artifacts and that the explanations\ngiven for the changes are incorrect.",
        "positive": "Competing weak localization and weak antilocalization in amorphous\n  indium-gallium-zinc-oxide thin-film transistors: We have investigated the gate-voltage dependence and the temperature\ndependence of the magnetoconductivity of amorphous indium-gallium-zinc-oxide\nthin-film transistors. A weak-localization feature is observed at small\nmagnetic fields on top of an overall negative magnetoconductivity at higher\nfields. An intriguing controllable competition between weak localization and\nweak antilocalization is observed by tuning the gate voltage or varying the\ntemperature. Our findings reflect controllable quantum interference competition\nin the electron systems in amorphous indium-gallium-zinc-oxide thin-film\ntransistors."
    },
    {
        "anchor": "Influence of contacts on the microwave response of a two-dimensional\n  electron stripe: Electromagnetic response of a finite-width two-dimensional electron stripe\nwith attached metallic side contacts is theoretically studied. It is shown that\ncontacts substantially influence the position, the linewidth, and the amplitude\nof plasmon-polariton resonances in the stripe. In finite magnetic fields,\nabsorption of the wave with the inactive circular polarization (which is not\nabsorbed in an infinite system without contacts) may become larger than that of\nthe wave with the active polarization. The results are discussed in view of\nrecent microwave experiments in two-dimensional electron systems.",
        "positive": "Mesoscopic Entanglement Induced by Spontaneous Emission in Solid-State\n  Quantum Optics: Implementations of solid state quantum optics provide us with devices where\nqubits are placed at fixed positions in photonic or plasmonic one dimensional\nwaveguides. We show that solely by controlling the position of the qubits and\nwith the help of a coherent driving, collective spontaneous decay may be\nengineered to yield an entangled mesoscopic steady-state. Our scheme relies on\nthe realization of pure superradiant Dicke models by a destructive interference\nthat cancels dipole-dipole interactions in one-dimension."
    },
    {
        "anchor": "Investigation of helicity-dependent photocurrent at room temperature\n  from a Fe/x-AlOx/p-GaAs Schottky junction with oblique surface illumination: In view of a study on spin-polarized photodiodes, the helicity-dependent\nphotocurrent in a Fe/x-AlOx/p-GaAs Schottky diode is measured at room\ntemperature by illuminating a circularly polarized light beam (785 nm) either\nhorizontally on the cleaved sidewall or at an oblique angle on the top metal\nsurface. The plane of incidence is fixed to be parallel to the magnetization\nvector of the in-plane magnetized Fe electrode. The conversion efficiency F,\nwhich is a relative value of helicity-dependent photocurrent with respect to\nthe total photocurrent, is determined to be 1.0*10^-3 and 1.2*10^-2 for\nsidewall illumination and oblique-angle illumination, respectively.\nExperimental data are compared with the results of a model calculation\nconsisting of drift-diffusion and Julliere spin-dependent tunneling transports,\nfrom which two conclusions are obtained: the model accounts fairly well for the\nexperimental data without introducing the annihilation of spin-polarized\ncarriers at the x-AlOx/p-GaAs interface for the oblique-angle illumination, but\nthe model does not fully explain the relatively low F in terms of the surface\nrecombination at the cleaved sidewall in the case of sidewall illumination.\nMicroscopic damage to the tunneling barrier at the cleaved edge would be one\npossible cause of the reduced F.",
        "positive": "Power-law dependence of the angular momentum transition fields in\n  few-electron quantum dots: We show that the critical magnetic fields at which a few-electron quantum dot\nundergoes transitions between successive values of its angular momentum (M),\nfor large M values follow a very simple power-law dependence on the effective\ninter-electron interaction strength. We obtain this power law analytically from\na quasi-classical treatment and demonstrate its nearly-universal validity by\ncomparison with the results of exact diagonalization."
    },
    {
        "anchor": "Very high frequency spectroscopy and tuning of a\n  single-Cooper-pair-transistor with an on-chip generator: We consider a single Cooper pair transistor (SCPT) coupled capacitively to a\nvoltage biased Josephson junction, used as a high frequency generator. Thanks\nto the high energy of photons generated by the Josephson junction, transitions\nbetween energy levels, not limited to the first two levels, were induced and\nthe effect of this irradiation on the DC Josephson current of the SCPT was\nmeasured. This allows to probe the phase and gate bias dependence of energy\nlevels of the SCPT at high energy. Because the energies of photons can be\nhigher than the superconducting gap we can induce not only transfer of Cooper\npairs but also transfer of quasi-particles through the island of the SCPT, thus\ncontrolling the poisoning of the SCPT. We show that this can both decrease and\nincrease the average Josephson energy of the SCPT : its supercurrent is then\ncontrolled by high-frequency",
        "positive": "Electron spin and charge switching in a coupled quantum dot quantum ring\n  system: Few-electron systems confined in a quantum dot laterally coupled to a\nsurrounding quantum ring in the presence of an external magnetic field are\nstudied by exact diagonalization. The distribution of electrons between the dot\nand the ring is influenced by the relative strength of the dot and ring\nconfinement, the gate voltage and the magnetic field which induces transitions\nof electrons between the two parts of the system. These transitions are\naccompanied by changes in the periodicity of the Aharonov-Bohm oscillations of\nthe ground-state angular momentum. The singlet-triplet splitting for a two\nelectron system with one electron confined in the dot and the other in the ring\nexhibits piecewise linear dependence on the external field due to the\nAharonov-Bohm effect for the ring-confined electron, in contrast to smooth\noscillatory dependence of the exchange energy for laterally coupled dots in the\nside-by-side geometry."
    },
    {
        "anchor": "Correlation-induced refrigeration with superconducting single-electron\n  transistors: A model of a superconducting tunnel junction which refrigerates a nearby\nmetallic island without any particle exchange is presented. Heat extraction is\nmediated by charge fluctuations in the coupling capacitance of the two systems.\nThe interplay of Coulomb interaction and the superconducting gap reduces the\npower consumption of the refrigerator. The island is predicted to be cooled\nfrom lattice temperatures of 200~mK down to close to 50~mK, for realistic\nparameters. The results emphasize the role of non-equilibrium correlations in\nbipartite mesoscopic conductors. This mechanism can be applied to create local\ntemperature gradients in tunnel junction arrays or explore the role of\ninteractions in the thermalization of non-equilibrium systems.",
        "positive": "Spin-Hall effect in a disordered 2D electron-system: We calculate the spin-Hall conductivity for a two-dimensional electron gas\nwithin the self-consistent Born approximation, varying the strength and type of\ndisorder. In the weak disorder limit we find both analytically and numerically\na vanishing spin-Hall conductivity even when we allow a momentum dependent\nscattering. Separating the reactive from the disspative current response, we\nfind the universal value $\\sigma^R_{sH} = e/8 \\pi$ for the reactive response,\nwhich cancels however with the dissipative part $\\sigma^D_{sH} = -e/8 \\pi$."
    },
    {
        "anchor": "Insights to negative differential resistance in\n  \\texorpdfstring{MoS\\textsubscript{2}}{MoS2} Esaki diodes: a first-principles\n  perspective: \\ce{MoS_2} is a two dimensional material with a band gap depending on the\nnumber of layers and tunable by an external electric field. The experimentally\nobserved intralayer band-to-band tunneling and interlayer band-to-band\ntunneling in this material present an opportunity for new electronic\napplications in tunnel field effect transistors. However, such a widely\naccepted concept has never been supported up by theoretical investigations\nbased on first principles. In this work, using density functional theory, in\nconjunction with non-equilibrilibrium Green's function techniques and our\nelectric field gating method, enabled by a large-scale computational approach,\nwe study the relation between band alignment and transmission in planar and\nside-stack \\ce{MoS_2} $p$-$i$-$n$ junction configurations. We demonstrate the\npresence of negative differential resistance for both in-plane and interlayer\ncurrent, a staple characteristic of tunnel diode junctions, and analyze the\nphysical origin of such an effect. Electrostatic potentials, the van der Waals\nbarrier, and complex band analysis are also examined for a thorough\nunderstanding of Esaki Diodes.",
        "positive": "Single-crystalline gold nanodisks on WS$_2$ mono- and multilayers:\n  Strong coupling at room temperature: Engineering light-matter interactions up to the strong-coupling regime at\nroom temperature is one of the cornerstones of modern nanophotonics. Achieving\nthis goal will enable new platforms for potential applications such as quantum\ninformation processing, quantum light sources and even quantum metrology.\nMaterials like transition metal dichalcogenides (TMDC) and in particular\ntungsten disulfide (WS$_2$) possess large transition dipole moments comparable\nto semiconductor-based quantum dots, and strong exciton binding energies\nallowing the detailed exploration of light-matter interactions at room\ntemperature. Additionally, recent works have shown that coupling TMDCs to\nplasmonic nanocavities with light tightly focused on the nanometer scale can\nreach the strong-coupling regime at ambient conditions. Here, we use ultra-thin\nsingle-crystalline gold nanodisks featuring large in-plane electromagnetic\ndipole moments aligned with the exciton transition-dipole moments located in\nmonolayer WS$_2$. Through scattering and reflection spectroscopy we demonstrate\nstrong coupling at room temperature with a Rabi splitting of $\\sim$108 meV. In\norder to go further into the strong-coupling regime and inspired by recent\nexperimental work by St\\\"uhrenberg et al., we couple these nanodisks to\nmultilayer WS$_2$. Due to an increase in the number of excitons coupled to our\nnanodisks, we achieve a Rabi splitting of $\\sim$175 meV, a major increase of\n62%. To our knowledge, this is the highest Rabi splitting reported for TMDCs\ncoupled to open plasmonic cavities. Our results suggest that ultra-thin\nsingle-crystalline gold nanodisks coupled to WS$_2$ represent an exquisite\nplatform to explore light-matter interactions."
    },
    {
        "anchor": "Effect of heating and cooling of photogenerated electron-hole plasma in\n  optically pumped graphene on population inversion: We study the characteristics of photogenerated electron-hole plasma in\noptically pumped graphene layers at elevated (room) temperatures when the\ninterband and intraband processes of emission and absorption of optical phonons\nplay a crucial role. The electron-hole plasma heating and cooling as well as\nthe effect of nonequilibrium optical phonons are taken into account. % The\ndependences of the quasi-Fermi energy and effective temperature of optically\npumped graphene layers on the intensity of pumping radiation are calculated.\nThe variation of the frequency dependences dynamic conductivity with increasing\npumping intensity as well as the conditions when this conductivity becomes\nnegative in a certain range of frequencies are considered. %\n  The effects under consideration can markedly influence the achievement of the\nnegative dynamic conductivity in optically pumped graphene layers associated\nwith the population inversion and, hence, the realization graphene-based\nterahertz and infrared lasers operating at room temperatures.",
        "positive": "Uniform doping of graphene close to the charge neutrality point by\n  polymer-assisted spontaneous assembly of molecular dopants: Tuning the charge carrier density of two-dimensional (2D) materials by\nincorporating dopants into the crystal lattice is a challenging task. An\nattractive alternative is the surface transfer doping by adsorption of\nmolecules on 2D crystals, which can lead to ordered molecular arrays. However,\nsuch systems, demonstrated in ultra-high vacuum conditions (UHV), are often\nunstable in ambient conditions. Here we show that air-stable doping of\nepitaxial graphene on SiC - achieved by spin-coating deposition of\n2,3,5,6-tetrafluoro-tetracyano-quino-dimethane (F4TCNQ) incorporated in poly\n(methyl-methacrylate) - proceeds via the spontaneous accumulation of dopants at\nthe graphene-polymer interface and by the formation of a charge-transfer\ncomplex that yields low-disorder, charge-neutral graphene with carrier\nmobilities ~70,000 cm2/Vs at cryogenic temperatures. The assembly of dopants on\n2D materials assisted by a polymer matrix, demonstrated by spin coating\nwafer-scale substrates in ambient conditions, opens up a scalable technological\nroute towards expanding the functionality of 2D materials."
    },
    {
        "anchor": "Modeling the Magnetization Dynamics for Large Ensembles of Immobilized\n  Magnetic Nanoparticles in Multi-dimensional Magnetic Particle Imaging: Magnetic nanoparticles (MNPs) play an important role in biomedical\napplications including imaging modalities such as MRI and magnetic particle\nimaging (MPI). The latter one exploits the non-linear magnetization response of\na large ensemble of magnetic nanoparticles to magnetic fields which allows\ndetermining the spatial distribution of the MNP concentration from measured\nvoltage signals. Currently, modeling the voltage signals of large ensembles of\nMNPs in an MPI environment is not yet accurately possible, especially for\nliquid tracers in multi-dimensional magnetic excitation fields. Thus, the\nvoltage-to-image mapping is still obtained in a time consuming calibration\nprocedure. While the ferrofluidic case can be seen as the typical setting, more\nrecently immobilized and potentially oriented MNPs have received considerable\nattention. By aligning the particles during immobilization, one can encode the\nangle of the easy axis into the magnetization response providing a\nsophisticated benchmark system for model-based approaches. In this work, we\naddress the modeling problem for immobilized, oriented MNPs in the context of\nMPI. We investigate a model-based approach where the magnetization response is\nsimulated by a N\\'eel rotation model for the particle's magnetic moments and\nthe ensemble magnetization is obtained by solving a Fokker-Planck equation\napproach. Since the parameters of the model are a-priori unknown, we\ninvestigate different methods for performing a parameter identification and\ndiscuss two models: One where a single function vector is used from the space\nspanned by the model parameters and another where a superposition of function\nvectors is considered. We show that our model can much more accurately\nreproduce the orientation dependent signal response when compared to the\nequilibrium model, which marks the current state-of-the-art for model-based\nsystem matrix simulations in MPI.",
        "positive": "Vertical transport and domain formation in multiple quantum wells: In this book article effects related to the vertical transport in weakly\ncoupled multiple quantum wells are reviewed. A self-contained microscopical\nmodel for the calculation of the well-to-well currents without any fittings\nparameters is presented. The model exhibits the well-known peaks in the\ncurrent-field relation in quantitative agreement with experiments. This local\ncurrent-field relation is used as an input for the calculation of the transport\nin the extended structure consisting of many periods. Here both the formation\nof stationary field domains as well as self-sustained current oscillations are\nfound in good agreement with experimental data. The underlying physics of these\nnonlinear phenomena is discussed in detail."
    },
    {
        "anchor": "Mean field exact solutions showing charge density wave crossover at low\n  fillings in the fractional quantum Hall regime: A general analytical framework for the determination of the mean field states\nat arbitrary rational filling factors for the 2DEG in FQHE regime is given. Its\nuse allows to obtain analytic expressions for the solutions at filling factors\nof the form $\\nu=1/q$ for arbitrary odd $q$. The analysis can be performed for\ntwo general classes of states characterized by $\\gamma=1$ or $\\gamma={1/2}$\nparticles per unit cell. Instead of the periodic peaks of the Wigner solid\nsolution, the new states show electron densities forming percolating ridges\nthat may favor an energy decrease through correlated ring of exchange\ncontributions. Therefore, we estimate that they can realize mean field versions\nof the so called Hall Crystal (HC) states. The obtained analytic HC solution\nshows the same crystalline symmetry that the corresponding WC state in its\nclass $\\gamma=1$, but a qualitatively different charge density distribution.\nThe energy dependence of the corresponding HC and WC states on the filling\nfactor is also evaluated here for the class $\\gamma=1/2$. The results show a\ncrossover between HC state and the Wigner crystal, close to filling 1/7.\nTherefore, transitions may occur from one to the other as the electron density\nis varied. This result is consistent with recent experimental findings.",
        "positive": "Clean BN encapsulated 2D FETs with lithography compatible contacts: Device passivation through ultraclean hexagonal BN encapsulation is proven\none of the most effective ways for constructing high-quality devices with\natomically thin semiconductors that preserves the ultraclean interface quality\nand intrinsic charge transport behavior. However, it remains challenging to\nintegrate lithography compatible contact electrodes with flexible distributions\nand patterns. Here, we report the feasibility in straightforwardly integrating\nlithography defined contacts into BN encapsulated 2D FETs, giving rise to\noverall device quality comparable to the state-of-the-art results from the\npainstaking pure dry transfer processing. Electronic characterization on FETs\nconsisting of WSe$_2$ and MoS$_2$ channels reveals an extremely low scanning\nhysteresis of ca. 2 mV on average, a low density of interfacial charged\nimpurity of ca. $10^{11}\\,$cm$^{-2}$, and generally high charge mobilities over\n$1000\\,$cm$^{2}\\cdot$V$^{-1}\\cdot$s$^{-1}$ at low temperatures. The overall\nhigh device qualities verify the viability in directly integrating lithography\ndefined contacts into BN encapsulated devices to exploit their intrinsic charge\ntransport properties for advanced electronics."
    },
    {
        "anchor": "Tunable Weyl fermions and Fermi arcs in magnetized topological\n  crystalline insulators: Based on $k\\cdot p$ analysis and realistic tight-binding calculations, we\nfind that time-reversal-breaking Weyl semimetals can be realized in\nmagnetically-doped (Mn, Eu, Cr etc.) Sn$_{1-x}$Pb$_x$(Te,Se) class of\ntopological crystalline insulators. All the Weyl points are well separated in\nmomentum space and possess nearly the same energy due to high crystalline\nsymmetry. Moreover, both the Weyl points and Fermi arcs are highly tunable by\nvarying Pb/Sn composition, pressure, magnetization, temperature, surface\npotential etc., opening up the possibility of manipulating Weyl points and\nrewiring the Fermi arcs.",
        "positive": "Chiral optical Local Density of States in spiral plasmonic cavity: We introduce a new paradigm: the chiral electromagnetic local density of\nstates (LDOS) in a spiral plasmonic nanostructure. In both classical and\nquantum regimes, we reveal using scanning near-field optical microscopy (NSOM)\nin combination with spin analysis that a spiral cavity possesses spin-dependent\nlocal optical modes. We expect this work to lead to promising directions for\nfuture quantum plasmonic device development, highlighting the potentials of\nchirality in quantum information processing."
    },
    {
        "anchor": "Role of Nuclear Quadrupole Coupling on Decoherence and Relaxation of\n  Central Spins in Quantum Dots: Strain-induced gradients of local electric fields in semiconductor quantum\ndots can couple to the quadrupole moments of nuclear spins. We develop a theory\ndescribing the influence of this quadrupolar coupling (QC) on the spin\ncorrelators of electron and hole \"central\" spins localized in such dots. We\nshow that when the QC strength is comparable to or larger than the hyperfine\ncoupling strength between nuclei and the central spin, the relaxation rate of\nthe central spin is strongly enhanced and can be exponential. We demonstrate a\ngood agreement with recent experiments on spin relaxation in hole-doped\n(In,Ga)As self-assembled quantum dots.",
        "positive": "Spin relaxation in a magnetic field in Al: The direct electrical method was used to study the behavior of the spin Hall\neffect in a magnetic field perpendicular to the injection current in aluminum\nsamples with resistivities that differed by two orders of magnitude at a\ntemperature of 4.2 K. The parabolic behavior of the spin-Hall voltage curves\nwith maxima at the same value of the magnetic field was discovered. It was\nproposed an explanation which is based on the competition of two universal\nmechanisms associated with the accumulation of spins - the dependences of spin\nmagnetization and spin relaxation length on the magnetic field strength."
    },
    {
        "anchor": "Co-tunneling current through the two-level quantum dot coupled to\n  magnetic leads: A role of exchange interaction: The co-tunneling current through a two-level doubly occupied quantum dot\nweakly coupled to ferromagnetic leads is calculated in the Coulomb blockade\nregime. It is shown that the dependence of the differrential conductance on\napplied voltage has a stair-case structure with different sets of \"stairs\" for\nparallel and anti-parallel configurations of magnetization of the leads.\nContributions to the current from elastic and inelastic processes are\nconsidered distinctly. It is observed that the interference part of the\nco-tunneling current involves terms corresponding to inelastic processes.\nDependence of the co-tunneling current on the phases of the tunneling\namplitudes is studied.",
        "positive": "A novel platform for two-dimensional chiral topological\n  superconductivity: We show that the surface of an $s$-wave superconductor decorated with a\ntwo-dimensional lattice of magnetic impurities can exhibit chiral topological\nsuperconductivity. If impurities order ferromagnetically and the\nsuperconducting surface supports a sufficiently strong Rashba-type spin-orbit\ncoupling, Shiba sub-gap states at impurity locations can hybridize into\nBogoliubov bands with non-vanishing, sometimes large, Chern number $C$. This\ntopological superconductor supports $C$ chiral Majorana edge modes. We\nconstruct phase diagrams for model two-dimensional superconductors, accessing\nthe dilute and dense magnetic impurity limits analytically and the intermediate\nregime numerically. To address potential experimental systems, we identify\nstable configurations of ferromagnetic iron atoms on the Pb (111) surface and\nconclude that ferromagnetic adatoms on Pb surfaces can provide a versatile\nplatform for two-dimensional topological superconductivity."
    },
    {
        "anchor": "Nonuniform Rashba-Dresselhaus spin precession along arbitrary paths: Electron spin precession in nonuniform Rashba-Dresselhaus two-dimensional\nelectron systems along arbitrary continuous paths is investigated. We derive an\nanalytical formula to describe the spin vectors (expectation values of the\ninjected spin) in such conditions using a contour-integral method. The obtained\nformalism is capable of dealing with the nonuniformity of the Rashba spin-orbit\nfield due to the inherent random distribution of the ionized dopants, and can\nbe applied to curved one-dimensional quantum wires. Interesting examples are\ngiven, and the modification to the spin precession pattern in a\nRashba-Dresselhaus channel when taking the random Rashba field into account is\nshown.",
        "positive": "Metallic bonds become molecular-like in atomic-sized devices: Covalent molecules are characterized by directed bonds, which provide\nstability-of-form to the molecules relative atomic positions. In contrast, bulk\nmetals are characterized by delocalized bonds, where a large number of\nresonance structures ensure their high stability. However, reduced to atomic\ndimensions, metallic arrangements become increasingly vulnerable to disruptive\nentropic fluctuations. Using the smallest possible device, namely, a single\natom held between two atomically sharp probes, force to rupture single-atom\nbridges was measured with pico-level resolution, using gold and silver.\nRemarkably, measured forces are found to be a precise vector sum (directional\nbonding) of cohesive forces between the central and adjacently coordinated\natoms. Over three to four times stronger than bulk, the directional bonds\nprovide high configurational stability to atomic-sized metallic devices, just\nas delocalization-induced resonance stabilization is the emergent response of\nbulk metals. Results open new opportunity for molecular electronics without\ncomplications arising from metal/molecule interfaces."
    },
    {
        "anchor": "Nonequlibrium particle and energy currents in quantum chains connected\n  to mesoscopic Fermi reservoirs: We propose a model of nonequilibrium quantum transport of particles and\nenergy in a system connected to mesoscopic Fermi reservoirs (meso-reservoir).\nThe meso-reservoirs are in turn thermalized to prescribed temperatures and\nchemical potentials by a simple dissipative mechanism described by the Lindblad\nequation. As an example, we study transport in monoatomic and diatomic chains\nof non-interacting spinless fermions. We show numerically the breakdown of the\nOnsager reciprocity relation due to the dissipative terms of the model.",
        "positive": "Direct observation of magnon BEC in an out-of-plane magnetized yttrium\n  iron garnet film: Bose-Einstain condensation occurs at an appropriate density of bosonic\nparticles, depending on their mass and temperature. We were able to\nexperimentally observe the transition from the spin wave regime to the magnon\nBose-Einstein condensed state (mBEC) with increasing magnon density by a\nmicrowave pumping. We used optical methods to register the spatial distribution\nof the magnon density and phase. For the first time, a coherent state of\nstationary magnons was demonstrated far from the region of their excitation."
    },
    {
        "anchor": "Electronic transport across quantum dots in graphene nanoribbons: Toward\n  built-in gap-tunable metal-semiconductor-metal heterojunctions: The success of all-graphene electronics is severely hindered by the\nchallenging realization and subsequent integration of semiconducting channels\nand metallic contacts. Here, we comprehensively investigate the electronic\ntransport across width-modulated heterojunctions consisting of a graphene\nquantum dot of varying lengths and widths embedded in a pair of armchair-edged\nmetallic nanoribbons, of the kind recently fabricated via on-surface synthesis.\nWe show that the presence of the quantum dot enables the opening of a\nwidth-dependent transport gap, thereby yielding built-in one-dimensional\nmetal-semiconductor-metal junctions. Furthermore, we find that, in the vicinity\nof the band edges, the conductance is subject to a smooth transition from an\nantiresonant to a resonant transport regime upon increasing the channel length.\nThese results are rationalized in terms of a competition between\nquantum-confinement effects and quantum dot-to-lead coupling. Overall, our work\nestablishes graphene quantum dot nanoarchitectures as appealing platforms to\nseamlessly integrate gap-tunable semiconducting channels and metallic contacts\ninto an individual nanoribbon, hence realizing self-contained carbon-based\nelectronic devices.",
        "positive": "Dirac materials under linear polarized light: quantum wave function\n  evolution and topological Berry phases as classical charged particles\n  trajectories under electromagnetic fields: The response of electrons under linearly polarized light in Dirac materials\nas borophene or graphene is analyzed in a continuous wave regime for an\narbitrary intense field. Using a rotation and a time-dependent phase\ntransformation, the wave function evolution is shown to be governed by a\nspinor-component decoupled Whittaker-Hill equation. The numerical solution of\nthese equations enables to find the quasienergy spectrum. For borophene it\nreveals a strong anisotropic response. By applying an extra unitary\ntransformation, the wave functions are proven to follow an Ince equation. The\nevolution of the real and imaginary parts of the wave function is interpreted\nas the trajectory of a classical charged particle under oscillating electric\nand magnetic field. The topological properties of this forced quantum system\nare studied using this analogy. In particular, in the adiabatic driving regime,\nthe system is described with an effective Matthieu equation while in the\nnon-adiabatic regime the full Whittaker-Hill equation is needed. From there, it\nis possible to separate the dynamical and Berry phase contributions to obtain\nthe topological phase diagram due to the driving. Therefore, a different path\nto perturbation theory is developed to obtain time-driven topological phases."
    },
    {
        "anchor": "Hybridized indirect excitons in MoS2/WS2 heterobilayers: Ensembles of indirect or interlayer excitons (IXs) are intriguing systems to\nexplore classical and quantum phases of interacting bosonic ensembles. IXs are\ncomposite bosons that feature enlarged lifetimes due to the reduced overlap of\nthe electron-hole wave functions. We demonstrate electric Field control of\nindirect excitons in MoS2/WS2 hetero-bilayers embedded in a field effect\nstructure with few-layer hexagonal boron nitrite as insulator and few-layer\ngraphene as gate-electrodes. The different strength of the excitonic dipoles\nand a distinct temperature dependence identify the indirect excitons to stem\nfrom optical interband transitions with electrons and holes located in\ndifferent valleys of the hetero-bilayer featuring highly hybridized electronic\nstates. For the energetically lowest emission lines, we observe a\nfield-dependent level anticrossing at low temperatures. We discuss this\nbehavior in terms of coupling of electronic states from the two semiconducting\nmonolayers resulting in spatially delocalized excitons of the hetero-bilayer\nbehaving like an artificial van der Waals solid. Our results demonstrate the\ndesign of novel nano-quantum materials prepared from artificial van der Waals\nsolids with the possibility to in-situ control their physical properties via\nexternal stimuli such as electric fields.",
        "positive": "Origin of spin dependent tunneling through chiral molecules: The functionality of many biological systems depends on reliable electron\ntransfer with minimal heating. Unlike man-made electric circuits, nature\nrealizes electron transport via insulating chiral molecules. Here we include\nspin into the analysis of tunneling through these molecules, and demonstrate\nits importance for efficient transport. We show that the helical geometry\ninduces robust spin filtering accompanied by, and intimately related to,\nstrongly enhanced transmission. Thus, we resolve two key questions posed by\ntransport measurements through organic molecules, demonstrating their common\norigin."
    },
    {
        "anchor": "Cyclic Superconducting Quantum Refrigerators Using Guided Fluxon\n  Propagation: We propose cyclic quantum refrigeration in solid-state, employing a gas of\nmagnetic field vortices in a type-II superconductor -- also known as fluxons --\nas the cooling agent. Refrigeration cycles are realized by envisioning a\nracetrack geometry consisting of both adiabatic and isothermal arms, etched\ninto a type-II superconductor. The guided propagation of fluxons in the\nracetrack is achieved by applying an external electrical current, in a Corbino\ngeometry, through the sample. A gradient of magnetic field is set across the\nracetrack allowing one to adiabatically cool down and heat up the fluxons,\nwhich subsequently exchange heat with the cold, and hot reservoirs,\nrespectively. We characterize the steady state of refrigeration cycles\nthermodynamically for both $s-$wave and $d-$wave pairing symmetries, and\npresent their figures of merit such as the cooling power delivered, and the\ncoefficient of performance. Our cooling principle can offer significant cooling\nfor on-chip micro-refrigeration purposes, by locally cooling below the base\ntemperatures achievable in a conventional dilution refrigerator. We estimate\n$10\\mathrm{nW}/\\mathrm{mm}^2$ of cooling power per unit area under typical\noperating conditions. Integrating the fluxon fridge to quantum circuits can\nenhance their coherence time by locally suppressing thermal fluctuations, and\nimprove the efficiency of single photon detectors and charge sensors.",
        "positive": "Femtosecond control of electric currents at the interfaces of metallic\n  ferromagnetic heterostructures: The idea to utilize not only the charge but also the spin of electrons in the\noperation of electronic devices has led to the development of spintronics,\ncausing a revolution in how information is stored and processed. A novel\nadvancement would be to develop ultrafast spintronics using femtosecond laser\npulses. Employing terahertz (10$^{12}$ Hz) emission spectroscopy, we\ndemonstrate optical generation of spin-polarized electric currents at the\ninterfaces of metallic ferromagnetic heterostructures at the femtosecond\ntimescale. The direction of the photocurrent is controlled by the helicity of\nthe circularly polarized light. These results open up new opportunities for\nrealizing spintronics in the unprecedented terahertz regime and provide new\ninsights in all-optical control of magnetism."
    },
    {
        "anchor": "Room temperature on-wafer ballistic graphene field-effect-transistor\n  with oblique double-gate: We have fabricated and measured ballistic graphene transistors with two\noblique gates that can be independently biased. The gate lengths are about 38\nnm and are separated by a distance of 30 nm, the tilting angle being of 45o\nwith respect to source and drain electrodes distanced at 190 nm. Electric\nmeasurements reveal specific properties of ballistic carrier transport, i.e.\nnonlinear drain voltage-drain current dependence, showing a saturation region,\nand negative differential resistance at certain bias voltages, which cannot be\nexplained without physical mechanisms related to ballistic transport. Tens of\nballistic transistors, with very large transconductances, were fabricated on a\nchip cut from a 4 inch graphene wafer. Such double-gate transistor\nconfigurations can be used also as extremely efficient, state-of-the-art\nphotodetectors.",
        "positive": "First-principles study of graphene edge properties and flake shapes: We use density functional theory to determine the equilibrium shape of\ngraphene flakes, through the calculation of the edge orientation dependence of\nthe edge energy and edge stress of graphene nanoribbons. The edge energy is a\nnearly linear function of edge orientation angle; increasing from the armchair\norientation to the zigzag orientation. Reconstruction of the zigzag edge lowers\nits energy to less than that of the armchair edge. The edge stress for all edge\norientations is compressive, however, reconstruction of the zigzag edge reduces\nthis edge stress to near zero. Hydrogen adsorption is favorable for all edge\norientations; dramatically lowering all edge energies and all edge stresses. It\nalso removes the reconstruction of the zigzag edge. Using the new edge energy\ndata, we determine the equilibrium shape of a graphene sheet (with\nunreconstructed edges) to be hexagonal with straight armchair edges in the\npresence and absence of hydrogen. However, zigzag edge reconstruction produces\ngraphene flakes with a six-fold symmetry, but with rounded edges. This shape is\ndominated by near zigzag edges. The compressive edge stresses will lead to edge\nbuckling (out-of-the-plane of the graphene sheet) for all edge orientations, in\nthe absence of hydrogen. Exposing the graphene flake to hydrogen dramatically\ndecreases the buckling amplitude."
    },
    {
        "anchor": "Nonstationary dephasing of two level systems: We investigate the influence of nonstationary 1/f^mu noise, produced by\ninteracting defects, on a quantum two-level system. Adopting a simple\nphenomenological model for this noise we describe exactly the corresponding\ndephasing in various regimes. The nonstationarity and pronounced non-Gaussian\nfeatures of this noise induce new anomalous dephasing scenarii. Beyond a\nhistory-dependent critical coupling strength the dephasing time exhibits a\nstrong dependence on the age of the noise and the decay of coherence is not\nexponential.",
        "positive": "Orbital Magnetism and Current Distribution of Two-Dimensional Electrons\n  under Confining Potential: The spatial distribution of electric current under magnetic field and the\nresultant orbital magnetism have been studied for two-dimensional electrons\nunder a harmonic confining potential $V(\\vecvar{r})=m \\omega_0^2 r^2/2$ in\nvarious regimes of temperature and magnetic field, and the microscopic\nconditions for the validity of Landau diamagnetism are clarified. Under a weak\nmagnetic field $(\\omega_c\\lsim\\omega_0, \\omega_c$ being a cyclotron frequency)\nand at low temperature $(T\\lsim\\hbar\\omega_0)$, where the orbital magnetic\nmoment fluctuates as a function of the field, the currents are irregularly\ndistributed paramagnetically or diamagnetically inside the bulk region. As the\ntemperature is raised under such a weak field, however, the currents in the\nbulk region are immediately reduced and finally there only remains the\ndiamagnetic current flowing along the edge. At the same time, the usual Landau\ndiamagnetism results for the total magnetic moment. The origin of this dramatic\ntemperature dependence is seen to be in the multiple reflection of electron\nwaves by the boundary confining potential, which becomes important once the\ncoherence length of electrons gets longer than the system length. Under a\nstronger field $(\\omega_c\\gsim\\omega_0)$, on the other hand, the currents in\nthe bulk region cause de Haas-van Alphen effect at low temperature as\n$T\\lsim\\hbar\\omega_c$. As the temperature gets higher $(T\\gsim\\hbar\\omega_c)$\nunder such a strong field, the bulk currents are reduced and the Landau\ndiamagnetism by the edge current is recovered."
    },
    {
        "anchor": "Quantum oscillations in metallic Sb2Te2Se topological insulator: We have studied the magnetotransport properties of the metallic, p-type\nSb2Te2Se which is a topological insulator. Magnetoresistance shows Shubnikov de\nHaas oscillations in fields above B=15 T. The maxima/minima positions of\noscillations measured at different tilt angles with respect to the B direction\nalign with the normal component of field Bcosine, implying the existence of a\n2D Fermi surface in Sb2Te2Se. The value of the Berry phase determined from a\nLandau level fan diagram is very close to 0.5, further suggesting that the\noscillations result from topological surface states. From Lifshitz-Kosevich\nanalyses, the position of the Fermi level is found to be EF =250 meV, above the\nDirac point. This value of EF is almost 3 times as large as that in our\nprevious study on the Bi2Se2:1Te0:9 topological insulator; however, it still\ntouches the tip of the bulk valence band. This explains the metallic behavior\nand hole-like bulk charge carriers in the Sb2Te2Se compound.",
        "positive": "Thermal shift of the resonance between an electron gas and quantum dots:\n  What is the origin?: The operation of quantum dots at highest possible temperatures is desirable\nfor many applications. Capacitance-voltage spectroscopy (C(V)-spectroscopy)\nmeasurements are an established instrument to analyze the electronic structure\nand energy levels of self-assembled quantum dots (QDs). We perform C(V) in the\ndark and C(V) under the influence of non-resonant illumination, probing exciton\nstates up to $X^{4+}$ on InAs QDs embedded in a GaAs matrix for temperatures\nranging from 2.5 K to 120 K. While a small shift in the charging spectra\nresonance is observed for the two pure spin degenerate electron s-state\ncharging voltages with increasing temperature, a huge shift is visible for the\nelectron-hole excitonic states resonance voltages. The $s_2$-peak moves to\nslightly higher, the $s_1$-peak to slightly lower charging voltages. In\ncontrast, the excitonic states are surprisingly charged at much lower voltages\nupon increasing temperature. We derive a rate-model allowing to attribute and\nvalue different contributions to these shifts. Resonant tunnelling, state\ndegeneracy and hole generation rate in combination with the Fermi distribution\nfunction turn out to be of great importance for the observed effects. The\ndifferences in the shifting behavior is connected to different equilibria\nschemes for the peaks; s-peaks arise when tunneling-in- and out-rates become\nequal, while excitonic peaks occur, when electron tunneling-in- and\nhole-generation rates are balanced."
    },
    {
        "anchor": "One-by-one trap activation in silicon nanowire transistors: Flicker or 1/f noise in metal-oxide-semiconductor field-effect transistors\n(MOSFETs) has been identified as the main source of noise at low frequency. It\noften originates from an ensemble of a huge number of charges trapping and\ndetrapping. However, a deviation from the well-known model of 1/f noise is\nobserved for nanoscale MOSFETs and a new model is required. Here, we report the\nobservation of one-by-one trap activation controlled by the gate voltage in a\nnanowire MOSFET and we propose a new low-frequency-noise theory for nanoscale\nFETs. We demonstrate that the Coulomb repulsion between electronically charged\ntrap sites avoids the activation of several traps simultaneously. This effect\ninduces a noise reduction by more than one order of magnitude. It decreases\nwhen increasing the electron density in the channel due to the electrical\nscreening of traps. These findings are technologically useful for any FETs with\na short and narrow channel.",
        "positive": "Gauge freedom in observables and Landsbergs nonadiabatic geometric\n  phase: pumping spectroscopy of interacting open quantum systems: We set up a general density-operator approach to geometric steady-state\npumping through slowly driven open quantum systems. This approach applies to\nstrongly interacting systems that are weakly coupled to multiple reservoirs at\nhigh temperature, illustrated by an Anderson quantum dot, but shows potential\nfor generalization. Pumping gives rise to a nonadiabatic geometric phase that\ncan be described by a framework originally developed for classical dissipative\nsystems by Landsberg. This geometric phase is accumulated by the transported\nobservable (charge, spin, energy) and not by the quantum state. It thus differs\nradically from the adiabatic Berry-Simon phase, even when generalizing it to\nmixed states, following Sarandy and Lidar. Importantly, our geometric\nformulation of pumping stays close to a direct physical intuition (i) by tying\ngauge transformations to calibration of the meter registering the transported\nobservable and (ii) by deriving a geometric connection from a driving-frequency\nexpansion of the current. Our approach provides a systematic and efficient way\nto compute the geometric pumping of various observables, including charge,\nspin, energy and heat. Our geometric curvature formula reveals a general\nexperimental scheme for performing geometric transport spectroscopy that\nenhances standard nonlinear spectroscopies based on measurements for static\nparameters. We indicate measurement strategies for separating the useful\ngeometric pumping contribution to transport from nongeometric effects. Finally,\nwe highlight several advantages of our approach in an exhaustive comparison\nwith the Sinitsyn-Nemenmann full-counting statistics (FCS) approach to\ngeometric pumping of an observable`s first moment. We explain how in the FCS\napproach an \"adiabatic\" approximation leads to a manifestly nonadiabatic result\ninvolving a finite retardation time of the response to parameter driving."
    },
    {
        "anchor": "Interaction of 3D mesostructures composed of Pd-Ni alloy nanowires with\n  low-temperature oxygen plasma: In this article we report about active interaction of volumetric mesoscopic\nstructures composed of PdNi alloy nanowires with low temperature nonequilibrium\noxygen plasma. Object of our study is fine 3D meso-structures, which were\nfabricated via a self-organization of nanowires growing during the\nelectrodeposition of metals on a template.",
        "positive": "Giant synthetic gauge field for spinless microcavity polaritons in\n  crossed electric and magnetic fields: The artificial gauge field for electrically neutral exciton polaritons devoid\nfrom the polarization degree of freedom can be synthesized by means of applying\ncrossed electric and magnetic fields. The appearance of the gauge potential can\nbe ascribed to the motional (magneto-electric) Stark effect which is\nresponsible for the presence of a linear-in-momentum contribution to the\nexciton kinetic energy. We study the interplay of this phenomenon with the\ncompeting effect which arises from the Rabi-splitting renormalization due the\nreduction of the electron-hole overlap for a moving exciton. Accounting for\nthis mechanism is crucial in the structures with the high ratio of Rabi\nsplitting and the exciton binding energy. Besides, we propose an approach which\nboosts the gauge field in the considered system. It takes advantage of the\ncrossover from the hydrogen-like exciton to the strongly dipole-polarized\nexciton state at a specific choice of electric and magnetic fields. The strong\nsensitivity of the exciton energy to the momentum in this regime leads to the\nlarge values of the gauge field. We consider the specific example of a GaAs\nring-shape polariton Berry phase interferometer and show that the flux of the\neffective magnetic field may approach the flux quantum value in the considered\ncrossover regime."
    },
    {
        "anchor": "Surface-induced reduction of the switching field in nanomagnets: Magnetization reversal in a many-spin nanomagnet subjected to an rf magnetic\nfield, on top of a DC magnetic field, is studied by numerically solving the\nsystem of coupled (damped) Landau-Lifshitz equations. It is demonstrated that\nspin-misalignment induced by surface anisotropy favors switching with a DC\nmagnetic field weaker than the Stoner-Wohlfarth switching field, for optimal\nintensities and frequencies of the rf field.",
        "positive": "Direct observation of van der Waals stacking dependent interlayer\n  magnetism: Controlling the crystal structure is a powerful approach for manipulating the\nfundamental properties of solids. Unique to two-dimensional (2D) van der Waals\nmaterials, the control can be achieved by modifying the stacking order through\nrotation and translation between the layers. Here, we report the first\nobservation of stacking dependent interlayer magnetism in the 2D magnetic\nsemiconductor, chromium tribromide (CrBr3), enabled by the successful growth of\nits monolayer and bilayer through molecular beam epitaxy. Using in situ\nspin-polarized scanning tunneling microscopy and spectroscopy, we directly\ncorrelated the atomic lattice structure with observed magnetic order. We\ndemonstrated that while individual CrBr3 monolayer is ferromagnetic, the\ninterlayer coupling in bilayer depends strongly on the stacking order and can\nbe either ferromagnetic or antiferromagnetic. Our observations provide direct\nexperimental evidence for exploring the stacking dependent layered magnetism,\nand pave the way for manipulating 2D magnetism with unique layer twist angle\ncontrol."
    },
    {
        "anchor": "Can nano-particle stand above the melting temperature of its fixed\n  surface partner?: The phonon thermal contribution to the melting temperature of nano-particles\nis inspected. Unlike in periodic boundary condition, under a general boundary\ncondition the integration volume of low energy phonon for a nano-particle is\nmore complex. We estimate the size-dependent melting temperature through the\nphase shift of the low energy phonon mode acquired by its scattering on\nboundary surface. A nano-particle can have either a rising or a decreasing\nmelting temperature due to the boundary condition effect, and we found that an\nupper melting temperature bound exists for a nano-particle in various\nenvironments. Moreover, the melting temperature under a fixed boundary\ncondition sets this upper bound.",
        "positive": "Spintronics via non-axisymmetric chiral skyrmions: Micromagnetic calculations demonstrate a peculiar evolution of\nnon-axisymmetric skyrmions driven by an applied magnetic field in confined\nhelimagnets with longitudinal modulations. We argue that these specific\nsolitonic states can be employed in nanoelectronic devices as an effective\nalternative to the common axisymmetric skyrmions which occur in magnetically\nsaturated states."
    },
    {
        "anchor": "Coulomb effects on topological band inversion in the moir\u00e9 of\n  WSe$_2$/BAs heterobilayer: Quantum spin Hall (QSH) insulator with large gap is highly desirable for\npotential spintronics application. Here we realize electrically tunable QSH\ninsulator with large gap in van der Waals heterobilayer of monolayer transition\nmetal dichalcogenide (TMD) and hexagonal BAs. When the type II band alignment\ngets inverted in an electric field, the hybridization by interlayer hopping\nbetween the spin-valley locked valence band edges in TMD and the BAs conduction\nband edges leads to a stacking-configuration dependent topological band\ninversion. In the non-interacting limit, the double spin degeneracy of BAs\nleaves an un-hybridized conduction band inside the gap, so the heterobilayer is\na spin-valley locked metal instead of a QSH insulator. With the Coulomb\ninteraction accounted in the double-layer geometry, the interaction with the\nhybridization induced electric dipole shifts this un-hybridized conduction band\nupwards in energy, giving rise to a sizable global QSH gap. Consequently, this\nheterobilayer provides a platform for engineering electrically tunable QSH\ninsulator with sizable band gap. In the long period moir\\'e pattern with the\nspatial variation of local stacking-configurations, the competition between\nCoulomb interaction and interlayer hopping leads to superstructures of QSH\ninsulators and excitonic insulators.",
        "positive": "Precision determination of a fluxoid quantum's magnetic moment in a\n  superconducting micro-ring: Using dynamic cantilever magnetometry and experimentally determining the\ncantilever's vibrational mode shape, we precisely measured the magnetic moment\nof a lithographically defined micron-sized superconducting Nb ring, a key\nelement for the previously proposed subpiconewton force standard. The magnetic\nmoments due to individual magnetic fluxoids and a diamagnetic response were\nindependently determined at T = 4.3 K, with a subfemtoampere-square-meter\nresolution. The results show good agreement with the theoretical estimation\nyielded by the Brandt and Clem model within the spring constant determination\naccuracy."
    },
    {
        "anchor": "Electric-field modification of interfacial spin-orbit field-vector: Current induced spin-orbit magnetic fields (iSOFs), arising either in\nsingle-crystalline ferromagnets with broken inversion symmetry1,2 or in\nnon-magnetic metal/ferromagnetic metal bilayers3,4, can produce spin-orbit\ntorques which act on a ferromagnet's magnetization,thus offering an efficient\nway for its manipulation.To further reduce power consumption in spin-orbit\ntorque devices, it is highly desirable to control iSOFs by the field-effect,\nwhere power consumption is determined by charging/discharging a capacitor5,6.\nIn particular, efficient electric-field control of iSOFs acting on\nferromagnetic metals is of vital importance for practical applications. It is\nknown that in single crystalline Fe/GaAs (001) heterostructures with C2v\nsymmetry, interfacial SOFs emerge at the Fe/GaAs (001) interface due to the\nlack of inversion symmetry7,8. Here, we show that by applying a gate-voltage\nacross the Fe/GaAs interface, interfacial SOFs acting on Fe can be robustly\nmodulated via the change of the magnitude of the interfacial spin-orbit\ninteraction. Our results show that, for the first time, the electric-field in a\nSchottky barrier is capable of modifying SOFs, which can be exploited for the\ndevelopment of low-power-consumption spin-orbit torque devices.",
        "positive": "Black Holes and Wormholes in spinor polariton condensates: We propose a new system for the study of event horizons and black holes - a\nBose-Einstein condensate of exciton-polaritons. Hawking radiation from a closed\nhorizon in 2D is observed in numerical experiments. We simulate inter-Universe\nand intra-Universe wormholes capitalizing on the spinor nature of polariton\ncondensates and on the spin dependence of polariton-polariton interactions."
    },
    {
        "anchor": "Skyrmions and multi-sublattice helical states in a frustrated chiral\n  magnet: We investigate the existence and stability of skyrmions in a frustrated\nchiral ferromagnet by considering the competition between ferromagnetic (FM)\nnearest-neighbour (NN) interaction ($J_1$) and antiferromagnetic (AFM)\nnext-nearest-neighbour (NNN) interaction ($J_2$). Contrary to the general\nwisdom that long-range ferromagnetic order is not energy preferable under\nfrustration, the skyrmion lattice not only exists but is even stable for a\nlarge field range when $J_2 \\leq J_1$ compared with frustration-free systems.\nWe defend that the enlargement of stability window of skyrmions is a\nconsequence of the reduced effective exchange interaction caused by the\nfrustration. A multi-sublattice helical state is found below the skyrmion\nphase, which results from the competition between AFM coupling that favors a\ntwo-sublattice N\\'{e}el state and the chiral interaction that prefers a helix.\nAs a byproduct, the hysteresis loop of the frustrated chiral system shrinks as\nthe magnetization goes to zero and then opens up again, known as wasp-waist\nhysteresis loop. The critical field that separates the narrow and wide part of\nthe wasp-waist loop depends exponentially on the strength of NNN coupling. By\nmeasuring the critical field, it is possible to determine the strength of NNN\ncoupling.",
        "positive": "Anisotropic thermal transport in bulk hexagonal boron nitride: Hexagonal boron nitride (h-BN) has received great interest in recent years as\na wide bandgap analog of graphene-derived systems. However, the thermal\ntransport properties of h-BN, which can be critical for device reliability and\nfunctionality, are little studied both experimentally and theoretically. The\nprimary challenge in the experimental measurements of the anisotropic thermal\nconductivity of h-BN is that typically sample size of h-BN single crystals is\ntoo small for conventional measurement techniques, as state-of-the-art\ntechnologies synthesize h-BN single crystals with lateral sizes only up to 2.5\nmm and thickness up to 200 {\\mu}m. Recently developed time-domain\nthermoreflectance (TDTR) techniques are suitable to measure the anisotropic\nthermal conductivity of such small samples, as it only requires a small area of\n50x50 {\\mu}m2 for the measurements. Accurate atomistic modeling of thermal\ntransport in bulk h-BN is also challenging due to the highly anisotropic\nlayered structure. Here we conduct an integrated experimental and theoretical\nstudy on the anisotropic thermal conductivity of bulk h-BN single crystals over\nthe temperature range of 100 K to 500 K, using TDTR measurements with multiple\nmodulation frequencies and a full-scale numerical calculation of the phonon\nBoltzmann transport equation starting from the first principles. Our\nexperimental and numerical results compare favorably for both the in-plane and\nthrough-plane thermal conductivities. We observe unusual temperature-dependence\nand phonon-isotope scattering in the through-plane thermal conductivity of h-BN\nand elucidate their origins. This work not only provides an important benchmark\nof the anisotropic thermal conductivity of h-BN but also develops fundamental\ninsights into the nature of phonon transport in this highly anisotropic layered\nmaterial."
    },
    {
        "anchor": "Trion Formation Dynamics in Monolayer Transition Metal Dichalcogenides: We report charged exciton (trion) formation dynamics in doped monolayer\ntransition metal dichalcogenides (TMDs), specifically molybdenum diselenide\n(MoSe2), using resonant two-color pump-probe spectroscopy. When resonantly\npumping the exciton transition, trions are generated on a picosecond timescale\nthrough exciton-electron interaction. As the pump energy is tuned from the high\nenergy to low energy side of the inhomogeneously broadened exciton resonance,\nthe trion formation time increases by ~ 50%. This feature can be explained by\nthe existence of both localized and delocalized excitons in a disordered\npotential and suggests the existence of an exciton mobility edge in TMDs. The\nquasiparticle formation and conversion processes are important for interpreting\nphotoluminescence and photoconductivity in TMDs.",
        "positive": "Gate-tunable quantum pathways of high harmonic generation in graphene: Under strong laser fields, electrons in solids radiate high-harmonic fields\nby travelling through quantum pathways in Bloch bands in the sub-laser-cycle\ntimescales. Understanding these pathways in the momentum space through the\nhigh-harmonic radiation can enable an all-optical ultrafast probe to observe\ncoherent lightwave-driven processes and measure electronic structures as\nrecently demonstrated for semiconductors. However, such demonstration has been\nlargely limited for semimetals because the absence of the bandgap hinders an\nexperimental characterization of the exact pathways. In this study, by\ncombining electrostatic control of chemical potentials with HHG measurement, we\nresolve quantum pathways of massless Dirac fermions in graphene under strong\nlaser fields. Electrical modulation of HHG reveals quantum interference between\nthe multi-photon interband excitation channels. As the light-matter interaction\ndeviates beyond the perturbative regime, elliptically polarized laser fields\nefficiently drive massless Dirac fermions via an intricate coupling between the\ninterband and intraband transitions, which is corroborated by our theoretical\ncalculations. Our findings pave the way for strong-laser-field tomography of\nDirac electrons in various quantum semimetals and their ultrafast electronics\nwith a gate control."
    },
    {
        "anchor": "The two-impurity Kondo model with spin-orbit interactions: We study the two-impurity Kondo model (TIKM) in two dimensions with\nspin-orbit coupled conduction electrons. In the first part of the paper we\nanalyze how spin-orbit interactions of Rashba as well as Dresselhaus type\ninfluence the Kondo and RKKY interactions in the TIKM, generalizing results\nobtained by H. Imamura {\\em et al.} (2004) and J. Malecki (2007). Using our\nfindings we then explore the effect from spin-orbit interactions on the\nnon-Fermi liquid quantum critical transition between the RKKY-singlet and\nKondo-screened RKKY-triplet states. We argue that spin-orbit interactions under\ncertain conditions produce a line of critical points exhibiting the same\nleading scaling behavior as that of the ordinary TIKM. In the second part of\nthe paper we shift focus and turn to the question of how spin-orbit\ninteractions affect the entanglement between two localized RKKY-coupled spins\nin the parameter regime where the competition from the direct Kondo interaction\ncan be neglected. Using data for a device with two spinful quantum dots\npatterned in a gated InAs heterostructure we show that a gate-controlled\nspin-orbit interaction may drive a maximally entangled state to one with\nvanishing entanglement, or vice versa (as measured by the concurrence). This\nhas important implications for proposals using RKKY interactions for nonlocal\ncontrol of qubit entanglement in semiconductor heterostructures.",
        "positive": "Dual orthogonally-polarized lasing assisted by imaginary Fermi arcs in\n  organic microcavities: The polarization control of micro/nano lasers is an important topic in\nnanophotonics. Up to now, the simultaneous generation of two distinguishable\northogonally-polarized lasing modes from a single organic microlaser remains a\ncritical challenge. Here, we demonstrate simultaneously orthogonally-polarized\ndual lasing from a microcavity filled with an organic single crystal exhibiting\nselective strong coupling. We show that the non-Hermiticity due to\npolarization-dependent losses leads to the formation of real and imaginary\nFermi arcs with exceptional points. Simultaneous orthogonally-polarized lasing\nbecomes possible thanks to the eigenstate mixing by the photonic spin-orbit\ncoupling at the imaginary Fermi arcs. Our work provides a novel way to develop\nlinearly-polarized lasers and paves the way for the future fundamental research\nin topological photonics, non-Hermitian optics, and other fields."
    },
    {
        "anchor": "Imaging nodal knots in momentum space through topolectrical circuits: Knots are intricate structures that cannot be unambiguously distinguished\nwith any single topological invariant. Momentum space knots, in particular,\nhave been elusive due to their requisite finely tuned long-ranged hoppings.\nEven if constructed, probing their intricate linkages and topological\n\"drumhead\" surface states will be challenging due to the high precision needed.\nIn this work, we overcome these practical and technical challenges with RLC\ncircuits, transcending existing theoretical constructions which necessarily\nbreak reciprocity, by pairing nodal knots with their mirror image partners in a\nfully reciprocal setting. Our nodal knot circuits can be characterized with\nimpedance measurements that resolve their drumhead states and image their 3D\nnodal structure. Doing so allows for reconstruction of the Seifert surface and\nhence knot topological invariants like the Alexander polynomial. We illustrate\nour approach with large-scale simulations of various nodal knots and an\nexperiment that maps out the topological drumhead region of a Hopf-link.",
        "positive": "Non-diagonal disorder enhanced topological properties of graphene with\n  laser irradiation: Laser irradiation, as a versatile tool to tune topological properties of\nelectronic systems, is under intensive studies. Experimentally, laser\nirradiation induced anomalous Hall effect in graphene has been observed (McIver\net al., Nat. Phys. 16, 38 (2020)). Disorder is ubiquitous in real materials,\nand it has been shown that diagonal disorders, i.e., onsite disorder, can\nenhance topological properties of time-periodically driven quantum materials\n(Titum et al., Phys. Rev. Lett. 114, 056801 (2015)). Here, we investigate\ncircularly polarized laser irradiated graphene with non-diagonal disorders,\ni.e., disordered tunneling, and find that disorder can induce nontrivial\ntopological properties, characterized by Bott index and the real-space Chern\nnumber. Moreover, we show that one can turn on the laser irradiation\nnon-adiabatically to drive the disordered graphene into non-trivial topological\nphase. It is a scheme which is especially interesting for experimental\nimplementations."
    },
    {
        "anchor": "Secondary proximity effect in a side-coupled double quantum dot\n  structure: Semiconductor quantum dots in close proximity to superconductors may provoke\nlocalized bound states within the superconducting energy gap known as\nYu-Shiba-Rusinov (YSR) state, which is a promising candidate for constructing\nMajorana zero modes and topological qubits. Side-coupled double quantum dot\nsystems are ideal platforms revealing the secondary proximity effect. Numerical\nrenormalization group calculations show that, if the central quantum dot can be\ntreated as a noninteracting resonant level, it acts as a superconducting medium\ndue to the ordinary proximity effect. The bound state in the side dot behaves\nas the case of a single impurity connected to two superconducting leads. The\nside dot undergoes quantum phase transitions between a singlet state and a\ndoublet state as the Coulomb repulsion, the interdot coupling strength, or the\nenergy level sweeps. Phase diagrams indicate that the phase boundaries could be\nwell illustrated by $\\Delta \\approx c {T_{K2}}$ in all cases, with $\\Delta$ is\nthe superconducting gap, $T_{K2}$ is the side Kondo temperature and $c$ is of\nthe order $1.0$. These findings offer valuable insights into the secondary\nproximity effect, and show great importance for designing superconducting\nquantum devices.",
        "positive": "Rotational and vibrational spectra of quantum rings: One can confine the two-dimensional electron gas in semiconductor\nheterostructures electrostatically or by etching techniques such that a small\nelectron island is formed. These man-made ``artificial atoms'' provide the\nexperimental realization of a text-book example of many-particle physics: a\nfinite number of quantum particles in a trap. Much effort was spent on making\nsuch \"quantum dots\" smaller and going from the mesoscopic to the quantum\nregime. Far-reaching analogies to the physics of atoms, nuclei or metal\nclusters were obvious from the very beginning: The concepts of shell structure\nand Hund's rules were found to apply -- just as in real atoms! In this Letter,\nwe report the discovery that electrons confined in ring-shaped quantum dots\nform rather rigid molecules with antiferromagnetic order in the ground state.\nThis can be seen best from an analysis of the rotational and vibrational\nexcitations."
    },
    {
        "anchor": "Graphene nano ribbons subjected to axial stress: Atomistic simulations are used to study the bending of rectangular graphene\nnano ribbons subjected to axial stress both for free boundary and supported\nboundary conditions. The shape of the deformations of the buckled graphene nano\nribbons, for small values of the stress, are sine waves where the number of\nnodal lines depend on the longitudinal size of the system and the applied\nboundary condition. The buckling strain for the supported boundary condition is\nfound to be independent of the longitudinal size and estimated to be 0.86$%$.\nFrom a calculation of the free energy at finite temperature we find that the\nequilibrium projected two-dimensional area of the graphene nano ribbon is less\nthan the area of a flat sheet. At the optimum length the boundary strain for\nthe supported boundary condition is 0.48$%$.",
        "positive": "Johnson-Nyquist noise in narrow wires: The Johnson-Nyquist noise in narrow semiconducting wires having a transverse\nsize smaller than the screening length is shown to be white up to frequency\n$D/L^2$ and to decay at higher frequencies as $\\omega^{-{1/2}}$. This result is\ncontrasted with the noise spectra in neutral and charged liquids."
    },
    {
        "anchor": "Impact of interface traps on charge noise, mobility and percolation\n  density in Ge/SiGe heterostructures: Hole spins in Ge/SiGe heterostructure quantum dots have emerged as promising\nqubits for quantum computation. The strong spin-orbit coupling (SOC),\ncharacteristic of heavy-hole states in Ge, enables fast and all-electrical\nqubit control. However, SOC also increases the susceptibility of spin qubits to\ncharge noise. While qubit coherence can be significantly improved by operating\nat sweet spots with reduced hyperfine or charge noise sensitivity, the latter\nultimately limits coherence, underlining the importance of understanding and\nreducing charge noise at its source. In this work, we study the voltage-induced\nhysteresis commonly observed in SiGe-based quantum devices and show that the\ndominant charge fluctuators are localized at the semiconductor-oxide interface.\nBy applying increasingly negative gate voltages to Hall bar and quantum dot\ndevices, we investigate how the hysteretic filling of interface traps impacts\ntransport metrics and charge noise. We find that the gate-induced accumulation\nand trapping of charge at the SiGe-oxide interface leads to an increased\nelectrostatic disorder, as probed by transport measurements, as well as the\nactivation of low-frequency relaxation dynamics, resulting in slow drifts and\nincreased charge noise levels. Our results highlight the importance of a\nconservative device tuning strategy and reveal the critical role of the\nsemiconductor-oxide interface in SiGe heterostructures for spin qubit\napplications.",
        "positive": "The crater function approach to ion-induced nanoscale pattern formation:\n  Craters for flat surfaces are insufficient: In the crater function approach to the erosion of a solid surface by a broad\nion beam, the average crater produced by the impact of an ion is used to\ncompute the constant coefficients in the continuum equation of motion for the\nsurface. We extend the crater function formalism so that it includes the\ndependence of the crater on the curvature of the surface at the point of\nimpact. We then demonstrate that our formalism yields the correct coefficients\nfor the Sigmund model of ion sputtering if terms up to second order in the\nspatial derivatives are retained. In contrast, if the curvature dependence of\nthe crater is neglected, the coefficients can deviate substantially from their\nexact values. Our results show that accurately estimating the coefficients\nusing craters obtained from molecular dynamics simulations will require\nsignificantly more computational power than was previously thought."
    },
    {
        "anchor": "Size-dependent spatial magnetization profile of manganese-zinc ferrite\n  Mn0.2Zn0.2Fe2.6O4 nanoparticles: We report the results of an unpolarized small-angle neutron scattering (SANS)\nstudy on Mn-Zn ferrite (MZFO) magnetic nanoparticles with the aim to elucidate\nthe interplay between their particle size and the magnetization configuration.\nWe study different samples of single-crystalline MZFO nanoparticles with\naverage diameters ranging between 8 to 80 nm, and demonstrate that the smallest\nparticles are homogeneously magnetized. However, with increasing nanoparticle\nsize, we observe the transition from a uniform to a nonuniform magnetization\nstate. Field-dependent results for the correlation function confirm that the\ninternal spin disorder is suppressed with increasing field strength. The\nexperimental SANS data are supported by the results of micromagnetic\nsimulations, which confirm an increasing inhomogeneity of the magnetization\nprofile of the nanoparticle with increasing size. The results presented\ndemonstrate the unique ability of SANS to detect even very small deviations of\nthe magnetization state from the homogeneous one.",
        "positive": "Large Enhancement of the Photoluminescence Emission of Photoexcited\n  Undoped GaAs Quantum Wells Induced by an Intense Single-Cycle Terahertz Pulse: Intense terahetz (THz) pulses induce a photoluminescence (PL) flash from\nundoped high-quality GaAs/AlGaAs quantum wells under continuous wave laser\nexcitation. The number of excitons increases 10000-fold from that of the steady\nstate under only laser excitation. The THz electric field dependence and the\nrelaxation dynamics of the PL flash intensity suggest that the strong electric\nfield of the THz pulse ionizes impurity states during the one-picosecond period\nof the THz pulse and release carriers from a giant reservoir containing\nimpurity states in the AlGaAs layers."
    },
    {
        "anchor": "A T-shaped double quantum dot system as a Fano interferometer: interplay\n  of coherence and correlation upon spin currents: Based on Keldysh non-equilibrium Green function method, we have investigated\nspin current production in a hybrid T-shaped device, consisting of a central\nquantum dot connected to the leads and a side dot which only couples to the\ncentral dot. The topology of this structure allows for quantum interference of\nthe different paths that go across the device, yielding Fano resonances in the\nspin dependent transport properties. Correlation effects are taken into account\nat the central dot and handled within a mean field approximation. Its interplay\nwith the Fano effect is analyzed in the strong coupling regime. Non-vanishing\nspin currents are only obtained when the leads are ferromagnetic, the current\nbeing strongly dependent on the relative orientation of the lead polarizations.\nWe calculate the conductance (spin and charge) by numerically differentiating\nthe current, and a rich structure is obtained as a manifestation of quantum\ncoherence and correlation effects. Increase of the Coulomb interaction produces\nlocalization of states at the side dot, largely suppressing Fano resonances.\nThe interaction is also responsible for the negative values of the spin\nconductance in some regions of the voltage near resonances, effect which is the\nspin analog of the Esaki tunnel diode. We also analyze control of the currents\nvia gate voltages applied to the dots, possibility which is interesting for\npractical operations.",
        "positive": "Enhancing phonon flow through 1D interfaces by Impedance Matching: We extend concepts from microwave engineering to thermal interfaces and\nexplore the principles of impedance matching in 1D. The extension is based on\nthe generalization of acoustic impedance to non linear dispersions using the\ncontact broadening matrix $\\Gamma(\\omega)$, extracted from the phonon self\nenergy. For a single junction, we find that for coherent and incoherent phonons\nthe optimal thermal conductance occurs when the matching $\\Gamma(\\omega)$\nequals the Geometric Mean (GM) of the contact broadenings. This criteria favors\nthe transmission of both low and high frequency phonons by requiring that (1)\nthe low frequency acoustic impedance of the junction matches that of the two\ncontacts by minimizing the sum of interfacial resistances; and (2) the cut-off\nfrequency is near the minimum of the two contacts, thereby reducing the\nspillage of the states into the tunneling regime. For an ultimately scaled\nsingle atom/spring junction, the matching criteria transforms to the arithmetic\nmean for mass and the harmonic mean for spring constant. The matching can be\nfurther improved using a composite graded junction with an exponential varying\nbroadening that functions like a broadband antireflection coating. There is\nhowever a trade off as the increased length of the interface brings in\nadditional intrinsic sources of scattering."
    },
    {
        "anchor": "In-plane critical magnetic fields in magic-angle twisted trilayer\n  graphene: It has recently been shown that superconductivity in magic-angle twisted\ntrilayer graphene survives to in-plane magnetic fields that are well in excess\nof the Pauli limit, and much stronger than the in-plane critical magnetic\nfields of magic-angle twisted bilayer graphene. The difference is surprising\nbecause twisted bilayers and trilayers both support the magic-angle flat bands\nthought to be the fountainhead of twisted graphene superconductivity. We show\nhere that the difference in critical magnetic fields can be traced to a\n$\\mathcal{C}_2 \\mathcal{M}_{h}$ symmetry in trilayers that survives in-plane\nmagnetic fields, and also relative displacements between top and bottom layers\nthat are not under experimental control at present. An gate electric field\nbreaks the $\\mathcal{C}_2 \\mathcal{M}_{h}$ symmetry and therefore limits the\nin-plane critical magnetic field.",
        "positive": "Tuning non-collinear magnetic states by hydrogenation: Two different superstructures form when atomic H is incorporated in the Fe\nmonolayer on Ir(111). Depending on the amount of H provided, either a highly\nordered p(2x2) hexagonal superstructure or an irregular roughly square\nstructure is created. We present here spin-polarized scanning tunneling\nmicroscopy (SP-STM) measurements which reveal that in both cases the magnetic\nnanoskyrmion lattice state of the pristine Fe monolayer is modified. Our\nmeasurements of the magnetic states in these hydrogenated films are in\nagreement with superpositions of cycloidal spin spirals which follow the\npattern and the symmetry dictated by the H superstructures. We thus demonstrate\nhere the possibility to vary the symmetry of a non-collinear magnetic state in\nan ultrathin film without changing its substrate."
    },
    {
        "anchor": "Odd-integer quantum Hall states and giant spin susceptibility in p-type\n  few-layer WSe2: We fabricate high-mobility p-type few-layer WSe2 field-effect transistors and\nsurprisingly observe a series of quantum Hall (QH) states following an\nunconventional sequence predominated by odd-integer states under a moderate\nstrength magnetic field. By tilting the magnetic field, we discover Landau\nlevel (LL) crossing effects at ultra-low coincident angles, revealing that the\nZeeman energy is about three times as large as the cyclotron energy near the\nvalence band top at {\\Gamma} valley. This result implies the significant roles\nplayed by the exchange interactions in p-type few-layer WSe2, in which\nitinerant or QH ferromagnetism likely occurs. Evidently, the {\\Gamma} valley of\nfew-layer WSe2 offers a unique platform with unusually heavy hole-carriers and\na substantially enhanced g-factor for exploring strongly correlated phenomena.",
        "positive": "Electronic structure and unconventional non-linear response in double\n  Weyl semimetal SrSi$_2$: Considering a non-centrosymmetric, non-magnetic double Weyl semimetal (WSM)\nSrSi$_2$, we investigate the electron and hole pockets in bulk Fermi surface\nbehavior that enables us to characterize the material as a type-I WSM. We study\nthe structural handedness of the material and correlate it with the distinct\nsurface Fermi surface at two opposite surfaces following an energy evolution.\nThe Fermi arc singlet becomes doublet with the onset of spin orbit coupling\nthat is in accordance with the topological charge of the Weyl Nodes (WNs). A\nfinite energy separation between WNs of opposite chirality in SrSi$_2$ allows\nus to compute circular photogalvanic effect (CPGE). Followed by the three band\nformula, we show that CPGE is only quantized for Fermi level chosen in the\nvicinity of WN residing at higher value of energy. Surprisingly, for the other\nWN of opposite chirality in the lower value of energy, CPGE is not found to be\nquantized. Such a behavior of CPGE is in complete contrast to the time reversal\nbreaking WSM where CPGE is quantized to two opposite plateau depending on the\ntopological charge of the activated WN. We further analyze our finding by\nexamining the momentum resolved CPGE. Finally we show that two band formula for\nCPGE is not able to capture the quantization that is apprehended by the three\nband formula."
    },
    {
        "anchor": "Real-time observation of charge-spin cooperative dynamics driven by a\n  nonequilibrium phonon environment: Quantum dots are recognized as a suitable platform for studying thermodynamic\nphenomena involving single electronic charges and spins in nano-scale devices.\nHowever, such a thermodynamic system is usually driven by electron reservoirs\nat different temperatures, not by a lattice temperature gradient. We report on\nexperimental observations of charge-spin cooperative dynamics in transitions of\ntwo-electron spin states in a GaAs double quantum dot located in a\nnon-equilibrium phonon environment. Enhancements in the spin-flip processes are\nobserved, originating from phonon excitation combined with the spin-orbit\ninteraction. In addition, due to the spatial gradient of phonon density between\nthe dots, the spin-flip rate during an inter-dot electron tunnel from a hot to\na cold dot is more enhanced than in the other direction, resulting in\naccumulation of parallel spin states in the double dot.",
        "positive": "Three-terminal transport through a quantum dot in the Kondo regime:\n  Conductance, dephasing, and current-current correlations: We investigate the nonequilibrium transport properties of a three-terminal\nquantum dot in the strongly interacting limit. At low temperatures, a Kondo\nresonance arises from the antiferromagnetic coupling between the localized\nelectron in the quantum dot and the conduction electrons in source and drain\nleads. It is known that the local density of states is accessible through the\ndifferential conductance measured at the (weakly coupled) third lead. Here, we\nconsider the multiterminal current-current correlations (shot noise and cross\ncorrelations measured at two different terminals). We discuss the dependence of\nthe current correlations on a number of external parameters: bias voltage,\nmagnetic field and magnetization of the leads. When the Kondo resonance is\nsplit by fixing the voltage bias between two leads, the shot noise shows a\nnontrivial dependence on the voltage applied to the third lead. We show that\nthe cross correlations of the current are more sensitive than the conductance\nto the appearance of an external magnetic field. When the leads are\nferromagnetic and their magnetizations point along opposite directions, we find\na reduction of the cross correlations. Moreover, we report on the effect of\ndephasing in the Kondo state for a two-terminal geometry when the third lead\nplays the role of a fictitious voltage probe."
    },
    {
        "anchor": "Self-duality in Maxwell-Chern-Simons theories with non minimal coupling\n  with field: We consider a general class of non-local MCS models whose usual minimal\ncoupling to a conserved current is supplemented with a (non-minimal) magnetic\nPauli-type coupling. We find that the considered models exhibit a self-duality\nwhenever the magnetic coupling constant reaches a special value: the partition\nfunction is invariant under a set of transformations among the parameter space\n(the duality transformations) while the original action and its dual\ncounterpart have the same form. The duality transformations have a structure\nsimilar to the one underlying self-duality of the (2+1)-dimensional Zn-abelian\nHiggs model with Chern-Simons and bare mass term.",
        "positive": "Terahertz Dynamics of Quantum-Confined Electrons in Carbon Nanomaterials: Low-dimensional carbon nanostructures, such as single-wall carbon nanotubes\n(SWCNTs) and graphene, offer new opportunities for terahertz science and\ntechnology. Being zero-gap systems with a linear, photon-like energy\ndispersion, metallic SWCNTs and graphene exhibit a variety of extraordinary\nproperties. Their DC and linear electrical properties have been extensively\nstudied in the last decade, but their unusual finite-frequency, nonlinear,\nand/or non-equilibrium properties are largely unexplored, although they are\npredicted to be useful for new terahertz device applications. Terahertz dynamic\nconductivity measurements allow us to probe the dynamics of such photon-like\nelectrons, or massless Dirac fermions. Here, we use terahertz time-domain\nspectroscopy and Fourier transform infrared spectroscopy to investigate\nterahertz conductivities of one-dimensional and two-dimensional electrons,\nrespectively, in films of highly aligned SWCNTs and gated large-area graphene.\nIn SWCNTs, we observe extremely anisotropic terahertz conductivities, promising\nfor terahertz polarizer applications. In graphene, we demonstrate that\nterahertz and infrared properties sensitively change with the Fermi energy,\nwhich can be controlled by electrical gating and thermal annealing."
    },
    {
        "anchor": "Electron-phonon coupling in the two phonon mode ternary alloy\n  $Al_{0.25}In_{0.75}As/Ga_{0.25}In_{0.75}As$ quantum well: We have investigated the infrared transmission of a two-dimensional (2DEG)\nelectron gas confined in a $Al_{0.25}In_{0.75}As/Ga_{0.25}In_{0.75}As$ single\nquantum well in order to study the electron optical phonon interaction in a two\nphonon mode system. Infrared transmission experiments have been performed in\nboth the perpendicular Faraday (PF) and tilted Faraday (TF) configurations for\nwhich the growth axis of the sample is tilted with respect to the incident\nlight propagation direction and to the magnetic field direction. The\nexperimental results lead to question the validity of the concept of polaron\nmass in a real material.",
        "positive": "Resources of polarimetric sensitivity in spin noise spectroscopy: We attract attention to the fact that the ultimate (shot-noise-limited)\npolarimetric sensitivity can be enhanced by orders of magnitude leaving the\nphoton flux incident onto the photodetector on the same low level. This\nopportunity is of crucial importance for present-day spin noise spectroscopy,\nwhere a direct increase of sensitivity by increasing the probe beam power is\nstrongly restricted by the admissible input power of the broadband\nphotodetectors. The gain in sensitivity is achieved by replacing the 45-deg\npolarization geometry commonly used in conventional schemes with balanced\ndetectors by geometries with stronger polarization extinction. The efficiency\nof these high-extinction polarization geometries with enhancement of the\ndetected signal by more than an order of magnitude is demonstrated by\nmeasurements of the spin noise spectra of bulk n:GaAs in the spectral range\n835-918 nm. It is shown that the inevitable growth of the probe beam power with\nthe sensitivity gain makes spin noise spectroscopy much more perturbative, but,\nat the same time, opens up fresh opportunities for studying nonlinear\ninteractions of strong light fields with spin ensembles."
    },
    {
        "anchor": "The topological system with a twisting edge band: position-dependent\n  Hall resistance: We study a $\\nu=1$ topological system with one twisting edge-state band and\none normal edge-state band. For the twisting edge-state band, Fermi energy goes\nthrough the band three times, thus, having three edge states on one side of the\nsample; while the normal edge band contributes only one edge state on the other\nside of the sample. In such a system, we show that it consists of both\ntopologically protected and unprotected edge states, and as a consequence, its\nHall resistance depends on the location where the Hall measurement is done even\nfor a translationally invariant system. This unique property is absent in a\nnormal topological insulator.",
        "positive": "Nonlinear magnetoresistance of an irradiated two-dimensional electron\n  system: Nonlinear magnetotransport of a microwave-irradiated high mobility\ntwo-dimensional electron system under a finite direct current excitation is\nanalyzed using a dc-controlled scheme with photon-assisted transition\nmechanism. The predicted amplitudes, extrema and nodes of the oscillatory\ndifferential resistance versus the magnetic field and the current density, are\nin excellent agreement with the recent experimental observation [Hatke et al.\nPhys. Rev. B 77, 201304(R) (2008)]."
    },
    {
        "anchor": "Mapping the Dirac point in gated bilayer graphene: We have performed low temperature scanning tunneling spectroscopy\nmeasurements on exfoliated bilayer graphene on SiO2. By varying the back gate\nvoltage we observed a linear shift of the Dirac point and an opening of a band\ngap due to the perpendicular electric field. In addition to observing a shift\nin the Dirac point, we also measured its spatial dependence using spatially\nresolved scanning tunneling spectroscopy. The spatial variation of the Dirac\npoint was not correlated with topographic features and therefore we attribute\nits shift to random charged impurities.",
        "positive": "Impact of capacitance and tunneling asymmetries on Coulomb blockade\n  edges and Kondo peaks in non-equilibrium transport through molecular quantum\n  dots: We investigate theorerically the non-equilibrium transport through a\nmolecular quantum dot as a function of gate and bias voltage, taking into\naccount the typical situation in molecular electronics. In this respect, our\nstudy includes asymmetries both in the capacitances and tunneling rates to the\nsource and drain electrodes, as well as an infinitely large charging energy on\nthe molecule. Our calculations are based on the out-of-equilibrium\nNon-Crossing-Approximation (NCA), which is a reliable technique in the regime\nunder consideration. We find that Coulomb blockade edges and Kondo peaks\ndisplay strong renormalization in their width and intensity as a function of\nthese asymmetries, and that basic expectations from Coulomb blockade theory\nmust be taken with care in general, expecially when Kondo physics is at play.\nIn order to help comparison of theory to experiments, we also propose a simple\nphenomenological model which reproduces semi-quantitatively the Coulomb\nblockade edges that were numerically computed from the NCA in all regimes of\nparameters."
    },
    {
        "anchor": "Effect of Curvature on the Electronic Structure and Bound State\n  Formation in Rolled-up Nanotubes: We analyze the electronic properties of a two-dimensional electron gas\nrolled-up into a nanotube by both numerical and analytical techniques. The\nnature and the energy dispersion of the electronic quantum states strongly\ndepend upon the geometric parameters of the nanotube: the typical radius of\ncurvature and the number of windings. The effect of the curvature results in\nthe appearance of atomic-like bound states localized near the points of maximum\ncurvature. For a two-dimensional sheet rolled up into an Archimedean spiral we\nfind that the number of bound states is equal to the number of windings of the\nspiral.",
        "positive": "Super-magnetoresistance effect in triplet spin valves: We study a triplet spin valve obtained by intercalating a triplet\nsuperconductor spacer between two ferromagnetic regions with non-collinear\nmagnetizations. We demonstrate that the magnetoresitance of the triplet spin\nvalve depends on the relative orientations of the d-vector, characterizing the\nsuperconducting state, and the magnetization directions of the ferromagnetic\nlayers. For devices characterized by a long superconductor, the Cooper pairs\nspintronics regime is reached allowing to observe the properties of a polarized\ncurrent sustained by Cooper pairs only. In this regime a\nsuper-magnetoresistance effect emerges, and the chiral symmetry of the order\nparameter of the superconducting spacer is easily recognized. Our findings open\nnew perspectives in designing devices based on the cooperative nature of\nferromagnetic and triplet correlations in a spintronic framework."
    },
    {
        "anchor": "Hall magnetoresistivity response under Microwave excitation revisited: We theoretically analyzed the microwave-induced modification of the Hall\nmagnetoresistivity in high mobility two-dimensional electron systems. These\nsystems present diagonal magnetoresistivity oscillations and zero-resistance\nstates when are subjected to microwave radiation. The most surprising\nmodification of the Hall magnetoresistivity is a periodic reduction which\ncorrelates with a periodic increase in the diagonal resistivity. We present a\nmodel that explains the experimental results considering that radiation affects\ndirectly only the diagonal resistivity and the observed Hall resistivity\nchanges are coming from the tensor relationship between both of them.",
        "positive": "Decoherence and the retrieval of lost information: We found that in contrast with the common premise, a measurement on the\nenvironment of an open quantum system can {\\em reduce} its decoherence rate. We\ndemonstrate it by studying an example of indirect qubit's measurement, where\nthe information on its state is hidden in the environment. This information is\nextracted by a distant device, coupled with the environment. We also show that\nthe reduction of decoherence generated by this device, is accompanied with\ndiminution of the environmental noise in a vicinity of the qubit. An\ninterpretation of these results in terms of quantum interference on large\nscales is presented."
    },
    {
        "anchor": "Dissipative entanglement generation between two driven qubits in circuit\n  quantum electrodynamics: An entangled state generation protocol for a system of two qubits driven with\nan ac signal and coupled through a resonator is introduced. We explain the\nmechanism of entanglement generation in terms of an interplay between unitary\nLandau-Zener-Stuckelberg (LZS) transitions induced for appropriate amplitudes\nand frequencies of the applied ac signal and dissipative processes dominated by\nphoton loss. In this way, we found that the steady state of the system can be\ntuned to be arbitrarily close to a Bell state, which is independent of the\ninitial state. Effective two-qubit Hamiltonians that reproduce the resonance\npatterns associated with LZS transitions are derived.",
        "positive": "Anomalous quantum Hall effect in epitaxial graphene: The observation of the anomalous quantum Hall effect in exfoliated graphene\nflakes triggered an explosion of interest in graphene. It was however not\nobserved in high quality epitaxial graphene multilayers grown on silicon\ncarbide substrates. The quantum Hall effect is shown on epitaxial graphene\nmonolayers that were deliberately grown over substrate steps and subjected to\nharsh processing procedures, demonstrating the robustness of the epitaxial\ngraphene monolayers and the immunity of their transport properties to\ntemperature, contamination and substrate imperfections. The mobility of the\nmonolayer C-face sample is 19,000 cm^2/Vs. This is an important step towards\nthe realization of epitaxial graphene based electronics."
    },
    {
        "anchor": "Effect of density on quantum Hall stripe orientation in tilted magnetic\n  fields: We investigate quantum Hall stripes under in-plane magnetic field\n$B_\\parallel$ in a variable-density two-dimensional electron gas. At filling\nfactor $\\nu = 9/2$, we observe one, two, and zero $B_\\parallel$-induced\nreorientations at low, intermediate, and high densities, respectively. The\nappearance of these distinct regimes is due to a strong density dependence of\nthe $B_\\parallel$-induced orienting mechanism which triggers the second\nreorientation, rendering stripes \\emph{parallel} to $B_\\parallel$. In contrast,\nthe mechanism which reorients stripes perpendicular to $B_\\parallel$ showed no\nnoticeable dependence on density. Measurements at $\\nu = 9/2$ and $11/2$ at the\nsame, tilted magnetic field, allows us to rule out density dependence of the\nnative symmetry-breaking field as a dominant factor. Our findings further\nsuggest that screening might play an important role in determining stripe\norientation, providing guidance in developing theories aimed at identifying and\ndescribing native and $B_\\parallel$-induced symmetry-breaking fields.",
        "positive": "On the second harmonic generation in superlattices: In present work, we investigate the second harmonic generation in a\nsuperlattice under presence of the carrier density gradient. We show that the\nsecond harmonic intensity can be comparable with that of the current\nfundamental harmonic in that case."
    },
    {
        "anchor": "Strongly coupled edge states in a graphene quantum Hall interferometer: Electronic interferometers using the chiral, one-dimensional (1D) edge\nchannels of the quantum Hall effect (QHE) can demonstrate a wealth of\nfundamental phenomena. The recent observation of phase jumps in a Fabry-P\\'erot\n(FP) interferometer revealed anyonic quasiparticle exchange statistics in the\nfractional QHE. When multiple integer edge channels are involved, FP\ninterferometers have exhibited anomalous Aharonov-Bohm (AB) interference\nfrequency doubling, suggesting putative pairing of electrons into 2e\nquasiparticles. Here, we use a highly tunable graphene-based QHE FP\ninterferometer to observe the connection between interference phase jumps and\nAB frequency doubling, unveiling how strong repulsive interaction between edge\nchannels leads to the apparent pairing phenomena. By tuning electron density\nin-situ from filling factor {\\nu}<2 to {\\nu}>7, we tune the interaction\nstrength and observe periodic interference phase jumps leading to AB frequency\ndoubling. Our observations demonstrate that the combination of repulsive\ninteraction between the spin-split {\\nu}=2 edge channels and charge\nquantization is sufficient to explain the frequency doubling, through a\nnear-perfect charge screening between the localized and extended edge channels.\nOur results show that interferometers are sensitive probes of microscopic\ninteractions and enable future experiments studying correlated electrons in 1D\nchannels using our highly tunable platform.",
        "positive": "Quantum transport in high-quality shallow InSb quantum wells: InSb is one of the promising candidates to realize a topological state\nthrough proximity induced superconductivity in a material with strong\nspin-orbit interactions. In two-dimensional systems, thin barriers are needed\nto allow strong coupling between superconductors and semiconductors. However,\nit is still challenging to obtain a high-quality InSb two-dimensional electron\ngas in quantum wells close to the surface. Here we report on a molecular beam\nepitaxy grown heterostructure of InSb quantum wells with substrate-side\nSi-doping and ultra-thin InAlSb (5 nm, 25 nm, and 50 nm) barriers to the\nsurface. We demonstrate that the carrier densities in these quantum wells are\ngate-tunable and electron mobilities up to 350,000 $\\rm{cm^2(Vs)^{-1}}$ are\nextracted from magneto-transport measurements. Furthermore, from\ntemperature-dependent magneto-resistance measurements, we extract an effective\nmass of 0.02 $m_0$ and find a Zeeman splitting compatible with the expected\ng-factor."
    },
    {
        "anchor": "Tunable Noise Cross-Correlations in a Double Quantum Dot: We report measurements of the cross-correlation between current noise\nfluctuations in two capacitively coupled quantum dots in the Coulomb blockade\nregime. The sign of the cross-spectral density is found to be tunable by gate\nvoltage and source-drain bias. Good agreement is found with a model of\nsequential tunneling through the dots in the presence of inter-dot capacitive\ncoupling.",
        "positive": "Fabrication of graphene nanogap with crystallographically matching edges\n  and its electron emission properties: We demonstrate the fabrication of graphene nanogap with crystallographically\nmatching edges on SiO2Si substrates by divulsion. The current-voltage\nmeasurement is then performed in a high-vacuum chamber for a graphene nanogap\nwith few hundred nanometers separation. The parallel edges help to build\nuniform electrical field and allow us to perform electron emission study on\nindividual graphene. It was found that current-voltage characteristics are\ngoverned by the space-charge-limited flow of current at low biases while the FN\nmodel fits the I-V curves in high voltage regime. We also examined\nelectrostatic gating effect of the vacuum electronic device. Graphene nanogap\nwith atomically parallel edges may open up opportunities for both fundamental\nand applied research of vacuum nanoelectronics."
    },
    {
        "anchor": "Quantum Shot Noise: 1. Types of electrical noise\n  2. Measuring the unit of transferred charge\n  3. Quiet electrons\n  4. Detecting open transmission channels\n  5. Distinguishing particles from waves\n  6. Entanglement detector",
        "positive": "Zero temperature geometric spin dephasing on a ring in presence of an\n  Ohmic environment: We study zero temperature spin dynamics of a particle confined to a ring in\npresence of spin orbit coupling and Ohmic electromagnetic fluctuations. We show\nthat the dynamics of the angular position $\\theta(t)$ are decoupled from the\nspin dynamics and that the latter is mapped to certain correlations of a\nspinless particle. We find that the spin correlations in the $z$ direction\n(perpendicular to the ring) are finite at long times, i.e. do not dephase. The\nparallel (in plane) components for spin $\\half$ do not dephase at weak\ndissipation but they probably decay as a power law with time at strong\ndissipation."
    },
    {
        "anchor": "Shiva and Kali diagrams for composite quantum particle many-body effects: For half a century, Feynman diagrams have provided an enlightening way of\nrepresenting many-body effects between elementary fermions and bosons. They\nhowever are quite inappropriate to visualize fermion exchanges taking place\nbetween a large number of composite quantum particles. We propose to replace\nthem by \"Shiva diagrams\" for cobosons made of two fermions and by Shiva-like\nand \"Kali diagrams\" for cofermions made of three fermions. We also show how\nthese fermion exchanges formally appear in a many-body theory appropriate to\ncomposite quantum particles. This theory relies on an operator algebra based on\ncommutators and anticommutators, the usual scalar algebra based on Green\nfunctions being valid for elementary bosons or fermions having strict\ncommutation relations, only.",
        "positive": "Non-Linear Thermovoltage in a Single-Electron Transistor: We perform direct thermovoltage measurements in a single-electron transistor,\nusing on-chip local thermometers, both in the linear and non-linear regimes.\nUsing a model which accounts for co-tunneling, we find excellent agreement with\nthe experimental data with no free parameters even when the temperature\ndifference is larger than the average temperature (far-from-linear regime).\nThis allows us to confirm the sensitivity of the thermovoltage on co-tunneling\nand to find that in the non-linear regime the temperature of the metallic\nisland is a crucial parameter. Surprisingly, the metallic island tends to\noverheat even at zero net charge current, resulting in a reduction of the\nthermovoltage."
    },
    {
        "anchor": "Using Ensemble Monte Carlo Methods to Evaluate Non-Equilibrium Green's\n  Functions, II. Polar-Optical Phonons: In semi-classical transport, it has become common practice over the past few\ndecades to use ensemble Monte Carlo (EMC) methods for the simulation of\ntransport in semiconductor devices. This method utilizes particles while still\naddressing the full physics within the device, leaving the computational\ndifficulties to the computer. More recently, the study of quantum mechanical\neffects within the devices, have become important, and have been addressed in\nsemiconductor devices using non-equilibrium Green's functions (NEGF). In using\nNEGF, one faces considerable computational difficulties. Recently, a particle\napproach to NEGF has been proposed [ 1], and preliminary results presented for\nnon-polar optical phonons, which are very localized scattering centers. Here,\nthe problems with long-range polar-optical phonons are discussed and results of\nthe particle-based simulation presented.",
        "positive": "Diameter-independent skyrmion Hall angle in the plastic flow regime\n  observed in chiral magnetic multilayers: Magnetic skyrmions are topologically non-trivial nanoscale objects. Their\ntopology, which originates in their chiral domain wall winding, governs their\nunique response to a motion-inducing force. When subjected to an electrical\ncurrent, the chiral winding of the spin texture leads to a deflection of the\nskyrmion trajectory, characterized by an angle with respect to the applied\nforce direction. This skyrmion Hall angle was believed to be skyrmion\ndiameter-dependent. In contrast, our experimental study finds that within the\nplastic flow regime the skyrmion Hall angle is diameter-independent. At an\naverage velocity of 6 $\\pm$ 1 m/s the average skyrmion Hall angle was measured\nto be 9{\\deg} $\\pm$ 2{\\deg}. In fact, in the plastic flow regime, the skyrmion\ndynamics is dominated by the local energy landscape such as materials defects\nand the local magnetic configuration."
    },
    {
        "anchor": "Engineering interaction-induced topological insulators in a $\\sqrt{3}\n  \\times \\sqrt{3}$ substrate-induced honeycomb superlattice: We consider a system of spinless fermions on the honeycomb lattice with\nsubstrate-induced modulated electrostatic potentials tripling the unit cell.\nThe resulting non-Abelian SU(2) gauge fields act cooperatively to realize a\nquadratic band crossing point (QBCP). Using a combination of mean-field theory\nand renormalization group techniques, we show that in the QBCP regime,\narbitrarily weak repulsive electronic interactions drive the system into the\nquantum anomalous Hall state. This proves that substrate-induced local voltages\nare an effective knob to induce the spontaneous formation of a topological\nquantum phase.",
        "positive": "Unifying first principle theoretical predictions and experimental\n  measurements of size effects on thermal transport in SiGe alloys: In this work, we demonstrate the correspondence between first principle\ncalculations and experimental measurements of size effects on thermal transport\nin SiGe alloys. Transient thermal grating (TTG) is used to measure the\neffective thermal conductivity. The virtual crystal approximation under the\ndensity functional theory (DFT) framework combined with impurity scattering is\nused to determine the phonon properties for the exact alloy composition of the\nmeasured samples. With these properties, classical size effects are calculated\nfor the experimental geometry of reflection mode TTG using the\nrecently-developed variational solution to the phonon Boltzmann transport\nequation (BTE), which is verified against established Monte Carlo simulations.\nWe find agreement between theoretical predictions and experimental measurements\nin the reduction of thermal conductivity (as much as $\\sim$ 25\\% of the bulk\nvalue) across grating periods spanning one order of magnitude. This work\nprovides a framework for the tabletop study of size effects on thermal\ntransport."
    },
    {
        "anchor": "New Paradigm for Edge Reconstruction of Fractional States: Part Two -\n  Noise: The recent, unexpected, findings of upstream neutral modes in particle-like\nfractional quantum Hall states, led to a realization that the nature of the\nneutral modes is far from being understood. Moreover, the observation of\nspatially separated of (at least) two downstream charge modes in hole-conjugate\nstates (see Part One - Conductance), still faces unresolved contradictions\nbetween conductance and noise measurements. In this work we show how current\nfluctuations measured in various configurations shed light on the interplay\nbetween neutral and charge modes. We demonstrate that once one of the charge\nmodes is taken out of equilibrium, counter-propagating neutral modes born in\nthe equilibration process affect the upstream charge modes, giving rise to a\nnovel mechanism for shot noise with quantized Fano factors. We present a\ntheoretical model that accounts for most of the experimental observations.",
        "positive": "Spin-Orbit Torques in ferrimagnetic GdFeCo Alloys: The spin-orbit torque switching of ferrimagnetic\nGd$_x$(Fe$_{90}$Co$_{10}$)$_{100-x}$ films was studied for both transition\nmetal (TM)-rich and rare earth (RE)-rich configurations. The spin-orbit torque\ndriven magnetization switching follows the same handedness in TM-rich and\nRE-rich samples with respect to the total magnetization, but the handedness of\nthe switching is reversed with respect to the TM magnetization. This indicates\nthat the sign of the spin-orbit-torque-driven magnetic switching follows the\ntotal magnetization, although transport based techniques such as anomalous Hall\neffect are only sensitive to the transition metal magnetization. These results\nprovide important insight into the physics of spin angular momentum transfer in\nmaterials with antiferromagnetically coupled sublattices."
    },
    {
        "anchor": "Spin dynamics of electrons and holes in InGaAs/GaAs quantum wells at\n  milliKelvin temperatures: The carrier spin dynamics in a n-doped (In,Ga)As/GaAs quantum well has been\nstudied by time-resolved Faraday rotation and ellipticity techniques in the\ntemperature range down to 430 milliKelvin. These techniques give data with very\ndifferent spectral dependencies, from which nonetheless consistent information\non the spin dynamics can be obtained, in agreement with theoretical\npredictions. The mechanisms of long-lived spin coherence generation are\ndiscussed for the cases of trion and exciton resonant excitation. We\ndemonstrate that carrier localization leads to a saturation of spin relaxation\ntimes at 45 ns for electrons below 4.5 K and at 2 ns for holes below 2.3 K. The\nunderlying spin relaxation mechanisms are discussed.",
        "positive": "Sub-Poissonian Shot Noise in Molecular Wires: We investigate the transport behavior of polyene molecules sandwiched between\ntwo metallic contacts using the non-equilibrium Green's function formalism. We\ncalculate both current and noise power as a function of applied voltage and\nshow that they decrease with increasing size of the polyene molecules. We find\nthat even with symmetric connection to metallic contacts, current verus voltage\ncurves can be asymmetric for asymmetrically substituted polyenes. Most\nimportantly, we demonstrate a cross-over from Poissonian to sub-Poissonian\nbehavior in the shot noise as a function of applied voltage. The algorithm for\nnoise power calculation can be used for designing molecules with low noise."
    },
    {
        "anchor": "Current-induced noise and damping in non-uniform ferromagnets: In the presence of spatial variation of the magnetization direction, electric\ncurrent noise causes a fluctuating spin-transfer torque that increases the\nfluctuations of the ferromagnetic order parameter. By the\nfluctuation-dissipation theorem, the equilibrium fluctuations are related to\nthe magnetization damping, which in non-uniform ferromagnets acquires a\nnonlocal tensor structure. In biased ferromagnets, shot noise can become the\ndominant contribution to the magnetization noise at low temperatures.\nConsidering spin spirals as a simple example, we show that the current-induced\nnoise and damping is significant.",
        "positive": "Nonparaxiality-triggered Landau-Zener transition in topological photonic\n  waveguides: Photonic lattices have been widely used for simulating quantum physics, owing\nto the similar evolutions of paraxial waves and quantum particles. However,\nnonparaxial wave propagations in photonic lattices break the paradigm of the\nquantum-optical analogy. Here, we reveal that nonparaxiality exerts stretched\nand compressed forces on the energy spectrum in the celebrated\nAubry-Andre-Harper model. By exploring the mini-gaps induced by the finite size\nof the different effects of nonparaxiality, we experimentally present that the\nexpansion of one band gap supports the adiabatic transfer of boundary states\nwhile Landau-Zener transition occurs at the narrowing of the other gap, whereas\nidentical transport behaviors are expected for the two gaps under paraxial\napproximation. Our results not only serve as a foundation of future studies of\ndynamic state transfer but also inspire applications leveraging nonparaxial\ntransitions as a new degree of freedom."
    },
    {
        "anchor": "Direct Observation of Infrared Plasmonic Fano Antiresonances by a\n  Nanoscale Electron Probe: In this Letter, we exploit recent breakthroughs in monochromated\naberration-corrected scanning transmission electron microscopy (STEM) to\nresolve infrared plasmonic Fano antiresonances in individual nanofabricated\ndisk-rod dimers. Using a combination of electron energy-loss spectroscopy\n(EELS) and theoretical modeling, we investigate and characterize a subspace of\nthe weak coupling regime between quasi-discrete and quasi-continuum localized\nsurface plasmon resonances where infrared plasmonic Fano antiresonances appear.\nThis work illustrates the capability of STEM instrumentation to experimentally\nobserve nanoscale plasmonic responses that were previously the domain only of\nhigher resolution infrared spectroscopies.",
        "positive": "Probing strong interactions in p-type few-layer WSe$_2$ by\n  density-dependent Landau level crossing: Atomically thin transition metal dichalcogenides (TMDCs) such as MoS$_2$ and\nWSe$_2$ are emerging as a new platform for exploring many-body effects. Coulomb\ninteractions are markedly enhanced in these materials because of the reduced\nscreening and the large Wigner-Seitz radii. Although many-body excitonic\neffects in TMDCs have been extensively studied by optical means, not until\nrecently did probing their strongly correlated electronic effects become\npossible in transport. Here, in p-type few-layer WSe$_2$ we observe highly\ndensity-dependent quantum Hall states of {\\Gamma} valley holes below 12 T,\nwhose predominant sequences alternate between odd- and even-integers. By\ntilting the magnetic field to induce Landau level crossings, we show that the\nstrong Coulomb interaction enhances the Zeeman-to-cyclotron energy ratio from\n2.67 to 3.55 as the density is reduced from 5.7 to 4.0$\\times$10$^{12}$\ncm$^{-2}$, giving rise to the even-odd alternation. Unprecedentedly, this\nindicates a 4.8 times enhancement of the g-factor over its band theory value at\na density as high as 4.0$\\times$10$^{12}$ cm$^{-2}$. Our findings unambiguously\ndemonstrate that p-type few-layer WSe$_2$ is a superior platform for exploring\nstrongly correlated electronic phenomena, opening a new perspective for\nrealizing the elusive Wigner crystallization at a moderate density."
    },
    {
        "anchor": "Magic ratios for connectivity-driven electrical conductance of\n  graphene-like molecules: Experiments using a mechanically-controlled break junction and calculations\nbased on density functional theory demonstrate a new magic ratio rule\n(MRR),which captures the contribution of connectivity to the electrical\nconductance of graphene-like aromatic molecules. When one electrode is\nconnected to a site i and the other is connected to a site i' of a particular\nmolecule, we assign the molecule a magic integer Mii'. Two molecules with the\nsame aromatic core, but different pairs of electrode connection sites (i,i' and\nj,j' respectively) possess different magic integers Mii' and Mjj'. Based on\nconnectivity alone, we predict that when the coupling to electrodes is weak and\nthe Fermi energy of the electrodes lies close to the centre of the HOMO-LUMO\ngap, the ratio of their conductances is equal to (Mii' /Mjj')2. The MRR is\nexact for a tight binding representation of a molecule and a qualitative guide\nfor real molecules.",
        "positive": "Topological Solitons versus Non-Solitonic Phase Defects in\n  Quasi-One-Dimensional Charge Density Wave: We investigated phase defects in a quasi-one-dimensional commensurate charge\ndensity wave (CDW) system, an In atomic wire array on Si(111), using low\ntemperature scanning tunneling microscopy. The unique four-fold degeneracy of\nthe CDW state leads to various phase defects, among which intrinsic solitons\nare clearly distinguished. The solitons exhibit a characteristic variation of\nthe CDW amplitude with a coherence length of about 4 nm, as expected from the\nelectronic structure, and a localized electronic state within the CDW gap.\nWhile most of the observed solitons are trapped by extrinsic defects, moving\nsolitons are also identified and their novel interaction with extrinsic defects\nis disclosed."
    },
    {
        "anchor": "Size dependent optical response in coupled systems of plasmons and\n  electron-hole pairs in metallic nanostructures: In bulk materials, the collective modes and individual modes are orthogonal\neach other, and no connection occurs if there is no damping processes. In the\npresence of damping, the collective modes, i.e., plasmons decay into the hot\ncarriers. In finite systems, the collective and individual modes are coupled by\nthe Coulomb interaction. Such couplings by longitudinal (L) field have been\nintensively investigated, whereas a coupling via transverse (T) field has been\npoorly studied although the plasmon is excited by an irradiated light on\nsurface and in finite nanostructures. Then, the T field would play a\nsignificant role in the coupling between the collective and individual\nexcitations. In this study, we investigate how the T field mediates the\ncoherent coupling. This study is based on the recently developed microscopic\nnonlocal theory of electronic systems in metals and the results of eigenmode\nanalyses by this theory. To tune the coupling strength in a single nanorod, we\nexamine three parameters: Rod length $L_z$, background refractive index $n_{\\rm\nb}$, and Fermi energy $\\varepsilon_{\\rm F}$. We discuss the modulation ratio of\nthe spectrum of optical response coefficients to evaluate the coupling by the T\nfield. The T field shifts the collective excitation energy, which causes a\nfinite modulation at both collective excitation and individual excitations. The\nthree parameters can change the energy distance between the collective and\nindividual excitations. Thus, the coherent coupling by the T field is enhanced\nfor a proper tuning of the parameters. The results of the investigation of\nsystem parameter dependence would give insight into the guiding principle of\ndesigning the materials for highly efficient hot carrier generation.",
        "positive": "Giant magnetoresistance of Dirac plasma in high-mobility graphene: The most recognizable feature of graphene's electronic spectrum is its Dirac\npoint around which interesting phenomena tend to cluster. At low temperatures,\nthe intrinsic behavior in this regime is often obscured by charge inhomogeneity\nbut thermal excitations can overcome the disorder at elevated temperatures and\ncreate electron-hole plasma of Dirac fermions. The Dirac plasma has been found\nto exhibit unusual properties including quantum critical scattering and\nhydrodynamic flow. However, little is known about the plasma's behavior in\nmagnetic fields. Here we report magnetotransport in this quantum-critical\nregime. In low fields, the plasma exhibits giant parabolic magnetoresistivity\nreaching >100% in 0.1 T even at room temperature. This is orders of magnitude\nhigher than magnetoresistivity found in any other system at such temperatures.\nWe show that this behavior is unique to monolayer graphene, being underpinned\nby its massless spectrum and ultrahigh mobility, despite frequent\n(Planckian-limit) scattering. With the onset of Landau quantization in a few T,\nwhere the electron-hole plasma resides entirely on the zeroth Landau level,\ngiant linear magnetoresistivity emerges. It is nearly independent of\ntemperature and can be suppressed by proximity screening, indicating a\nmany-body origin. Clear parallels with magnetotransport in strange metals and\nso-called quantum linear magnetoresistance predicted for Weyl metals offer an\ninteresting playground to further explore relevant physics using this\nwell-defined quantum-critical 2D system."
    },
    {
        "anchor": "Excess resistivity in graphene superlattices caused by umklapp\n  electron-electron scattering: Umklapp processes play a fundamental role as the only intrinsic mechanism\nthat allows electrons to transfer momentum to the crystal lattice and,\ntherefore, provide a finite electrical resistance in pure metals. However,\numklapp scattering has proven to be elusive in experiment as it is easily\nobscured by other dissipation mechanisms. Here we show that electron-electron\numklapp scattering dominates the transport properties of\ngraphene-on-boron-nitride superlattices over a wide range of temperatures and\ncarrier densities. The umklapp processes cause giant excess resistivity that\nrapidly increases with increasing the superlattice period and are responsible\nfor deterioration of the room-temperature mobility by more than an order of\nmagnitude as compared to standard, non-superlattice graphene devices. The\numklapp scattering exhibits a quadratic temperature dependence accompanied by a\npronounced electron-hole asymmetry with the effect being much stronger for\nholes rather than electrons. Aside from fundamental interest, our results have\ndirect implications for design of possible electronic devices based on\nheterostructures featuring superlattices.",
        "positive": "An ab initio perspective on scanning tunneling microscopy measurements\n  of the tunable Kondo resonance of the TbPc$_2$ molecule on a gold substrate: With recent advances in the areas of nanostructure fabrication and molecular\nspintronics the idea of using single molecule magnets as building blocks for\nthe next generation electronic devices becomes viable. A particular example\nrepresents a metal-organic complex in which organic ligands surround a\nrare-earth element or transition metal. Recently, it was explicitly shown that\nthe relative position of the ligands with respect to each other can be\nreversibly changed by the external voltage without any need of the chemical\nmodification of the sample. This opens a way of the electrical tuning of the\nKondo effect in such metal-organic complexes. In this work, we present a\ndetailed and systematic analysis of this effect in TbPc$_2$ from an ab initio\nperspective and compare the obtained results with the existing experimental\ndata."
    },
    {
        "anchor": "Spin-Torque Driven Magnetization Dynamics: Micromagnetic Modelling: In this paper we present an overview of recent progress made in the\nunderstanding of the spin-torque induced magnetization dynamics in nanodevices\nusing mesoscopic micromagnetic simulations. We first specify how a spin-torque\nterm may be added to the usual Landau-Lifshitz-Gilbert equation of\nmagnetization motion and detail its physical meaning. After a brief description\nof spin-torque driven dynamics in the macrospin approximation, we discuss the\nvalidity of this approximation for various experimentally relevant geometries.\nNext, we perform a detailed comparison between accurate experimental data\nobtained from nanopillar devices and corresponding numerical modelling. We show\nthat, on the one hand, many qualitatively important features of the observed\nmagnetization dynamics (e.g., non-linear frequency shift and frequency jumps\nwith increasing current) can be satisfactory explained by sophisticated\nmicromagnetic models, but on the other hand, understanding of these experiments\nis still far from being complete. We proceed with the numerical analysis of\npoint-contact experiments, where an even more complicated magnetization\ndynamics is observed. Simulations reveal that such a rich behaviour is due to\nthe formation of several strongly non-linear oscillation modes. In the last\npart of the paper we emphasize the importance of sample characterization and\nconclude with some important remarks concerning the relation between\nmicromagnetic modelling and real experiments.",
        "positive": "Two Distinct Phases of Bilayer Graphene Films on Ru(0001): By combining angle-resolved photoemission spectroscopy and scanning tunneling\nmicroscopy we reveal the structural and electronic properties of multilayer\ngraphene on Ru(0001). We prove that large ethylene exposure allows to\nsynthesize two distinct phases of bilayer graphene with different properties.\nThe first phase has Bernal AB stacking with respect to the first graphene\nlayer, displays weak vertical interaction and electron doping. The long-range\nordered moir\\'e pattern modulates the crystal potential and induces replicas of\nthe Dirac cone and minigaps. The second phase has AA stacking sequence with\nrespect to the first layer, displays weak structural and electronic modulation\nand p-doping. The linearly dispersing Dirac state reveals the\nnearly-freestanding character of this novel second layer phase."
    },
    {
        "anchor": "Time ordering and counting statistics: The basic quantum mechanical relation between fluctuations of transported\ncharge and current correlators is discussed. It is found that, as a rule, the\ncorrelators are to be time-ordered in an unusual way. Instances where the\ndifference with the conventional ordering matters are illustrated by means of a\nsimple scattering model. We apply the results to resolve a discrepancy\nconcerning the third cumulant of charge transport across a quantum point\ncontact.",
        "positive": "Impact of interparticle dipole-dipole interactions on optical\n  nonlinearity of nanocomposites: In this paper, effect of dipole-dipole interactions on nonlinear optical\nproperties of the system of randomly located semiconductor nanoparticles\nembedded in bulk dielectric matrix is investigated. This effect results from\nthe nonzero variance of the net dipole field in an ensemble. The analytical\nexpressions describing the contribution of the dipole-dipole coupling to\nnonlinear dielectric susceptibility are obtained. The derived relationships are\napplicable over the full range of nanoparticle volume fractions. The factors\nentering into the contribution and depending on configuration of the dipoles\nare calculated for several cases. It is shown that for the different\narrangements of dipole alignments the relative change of this contribution does\nnot exceed 1/3."
    },
    {
        "anchor": "Giant resonant radiative heat transfer between nanoparticles: We show that periodic multilayered structures allow to drastically enhance\nnear-field radiative heat transfer between nanoparticles. In particular, when\nthe two nanoparticles are placed on each side of the multilayered structure, at\nthe same interparticle distance the resulting heat transfer is more than five\norders of magnitude higher than that in the absence of the multilayered\nstructure. This enhancement takes place in a broad range of distances and is\ndue to the fact that the intermediate multilayered structure supports\nhyperbolic phonon polaritons with the key feature that the edge frequencies of\nthe Type I and Type II Reststrahlen bands coincide with each other at a value\nextremely close to the particle resonance. This allow a very high-k evanescent\nmodes resonating with the nanoparticles. Our predictions can be relevant for\neffective managing of energy at the nano-scale.",
        "positive": "The effect of the electron-electron interaction on the Lifshitz\n  transition density in bilayer graphene: We study the renormalization of the effective mass and trigonal warping of\nbilayer graphene by the electron-electron interaction. One consequence of such\na renormalization in the low-energy bands of a bilayer crystal consists of a\nsmall reduction of the critical density of the Lifshitz transition (the\ncrossover between the single-pocket and four-pocket topology of the Fermi\nsurface)."
    },
    {
        "anchor": "Weakly interacting one-dimensional topological insulators: a\n  bosonization approach: We investigate the topological properties of one-dimensional weakly\ninteracting topological insulators using bosonization. To do that we study the\ntopological edge states that emerge at the edges of a model realized by a\nstrong impurity or at the boundary between topologically distinct phases. In\nthe bosonic model, the edge states are manifested as degenerate bosonic kinks\nat the boundaries. We first illustrate this idea on the example of the\ninteracting Su-Schrieffer-Heeger (SSH) chain. We compute the localization\nlength of the edge states as the width of an edge soliton that occurs in the\nSSH model in the presence of a strong impurity. Next, we examine models of two\ncapacitively coupled SSH chains that can be either identical or in distinct\ntopological phases. We find that weak Hubbard interaction reduces the ground\nstate degeneracy in the topological phase of identical chains. We then prove\nthat similarly to the non-interacting model, the degeneracy of the edge states\nin the interacting case is protected by chiral symmetry. We then study\ntopological insulators built from two SSH chains with inter-chain hopping, that\nrepresent models of different chiral symmetric universality classes. We\ndemonstrate in bosonic language that the topological index of a weakly coupled\nmodel is determined by the type of inter-chain coupling, invariant under one of\ntwo possible chiral symmetry operators. Finally, we show that a general\none-dimensional model in a phase with topological index $\\nu$ is equivalent at\nlow energies to a theory of at least $\\nu$ SSH chains. We illustrate this idea\non the example of an SSH model with longer-range hopping.",
        "positive": "Manipulating single excess electrons in monolayer transition metal\n  dihalide: Polarons are entities of excess electrons dressed with local response of\nlattices, whose atomic-scale characterization is essential for understanding\nthe many body physics arising from the electron-lattice entanglement, but yet\ndifficult to achieve. Here, using scanning tunneling microscopy and\nspectroscopy (STM/STS), we show the visualization and manipulation of single\npolarons with different origin, i.e., electronic and conventional polarons, in\nmonolayer CoCl2, that are grown on HOPG substrate via molecular beam epitaxy.\nFour types of polarons are identified, all inducing upward local band bending,\nbut exhibiting distinct appearances, lattice occupations, polaronic states and\nlocal lattice distortions. First principles calculations unveil three types of\npolarons are stabilized by electron-electron interaction. The type-4 polaron,\nhowever, are driven by conventional lattice distortions. All the four types of\npolarons can be created, moved, erased, and moreover interconverted\nindividually by the STM tip, allowing precise control of single polarons\nunprecedently. This finding identifies the rich category of polarons and their\nfeasibility of manipulation in CoCl2, which can be generalized to other\ntransition metal halides."
    },
    {
        "anchor": "Controlling transport properties of graphene nanoribbons by\n  codoping-induced edge distortions: One notable manifestation of the peculiar edge-localized states in zigzag\ngraphene nanoribbons (zGNRs) is the p-type (n-type) characteristics of nitrogen\n(boron) edge-doped GNRs, and such behavior was so far considered to be\nexclusive for zGNRs. Carrying out first-principles electronic structure and\nquantum transport calculations, we herein show that the donor-acceptor\ntransition behavior can also arise in the B/N edge-doped armchair GNRs (aGNRs)\nby introducing a bipolar P codopant atom into the energetically most favorable\nnearest neighbor edge sites. The n-type (p-type) transport properties of B,P\n(N,P) co-doped aGNRs are also shown to be superior to those of reference single\nN (B) doped aGNRs in that the valence (conduction) band edge conductance\nspectra are better preserved. Disentangling the chemical doping and structural\ndistortion effects, we will demonstrate that the latter plays an important role\nin determining the transport type and explains the donor-acceptor transition\nfeature as well as the bipolar character of P-doped aGNRs. We thus propose the\nsystematic modification of GNR edge atomic structures via co-doping as a novel\napproach to control charge transport characteristics of aGNRs.",
        "positive": "Duality and integer quantum Hall effect in isotropic 3D crystals: We show here a series of energy gaps as in Hofstadter's butterfly, which have\nbeen shown to exist by Koshino et al [Phys. Rev. Lett. 86, 1062 (2001)] for\nanisotropic three-dimensional (3D) periodic systems in magnetic fields\n$\\Vec{B}$, also arise in the isotropic case unless $\\Vec{B}$ points in\nhigh-symmetry directions. Accompanying integer quantum Hall conductivities\n$(\\sigma_{xy}, \\sigma_{yz}, \\sigma_{zx})$ can, surprisingly, take values\n$\\propto (1,0,0), (0,1,0), (0,0,1)$ even for a fixed direction of $\\Vec{B}$\nunlike in the anisotropic case. We can intuitively explain the high-magnetic\nfield spectra and the 3D QHE in terms of quantum mechanical hopping by\nintroducing a ``duality'', which connects the 3D system in a strong $\\Vec{B}$\nwith another problem in a weak magnetic field $(\\propto 1/B)$."
    },
    {
        "anchor": "Composite Fermion States around 2D Hole Landau Level Filling Factor 3/2\n  in Tilted Magnetic Fields: Transport measurements under a tilted magnetic field were performed on a\nseries of C-doped (001) AlGaAs/GaAs/AlGaAs two-dimensional hole samples. Due to\na large g-factor, Zeeman energy is large and comparable to the cyclotron energy\nin these samples. On the other hand, it was found that the in-plane component\ng// is small, and the effect of tilted magnetic field is mainly to increase the\neffective mass of holes. We investigate the spin transition of composite\nfermion states around Landau level (LL) filling factor 3/2. We found that the\n{\\nu} = 4/3 state encounters a partial to full spin polarization transition,\nconforming to the same pattern as that of electron samples. In addition,\nhigh-resistance phase emerges at {\\nu} = 3/2 under very high tilt angles. We\ninterpret both of these phenomena as a consequence of LL crossings that are\nmainly driven by the orbital effects. The roles that the spin degrees of\nfreedom play in FQH states around {\\nu} = 3/2 in these systems will be\ndiscussed.",
        "positive": "Nature of carrier injection in metal/2D semiconductor interface and its\n  implications to the limits of contact resistance: Monolayers of transition metal dichalcogenides (TMDCs) exhibit excellent\nelectronic and optical properties. However, the performance of these\ntwo-dimensional (2D) devices are often limited by the large resistance offered\nby the metal contact interface. Till date, the carrier injection mechanism from\nmetal to 2D TMDC layers remains unclear, with widely varying reports of\nSchottky barrier height (SBH) and contact resistance (Rc), particularly in the\nmonolayer limit. In this work, we use a combination of theory and experiments\nin Au and Ni contacted monolayer MoS2 device to conclude the following points:\n(i) the carriers are injected at the source contact through a cascade of two\npotential barriers - the barrier heights being determined by the degree of\ninteraction between the metal and the TMDC layer; (ii) the conventional\nRichardson equation becomes invalid due to the multi-dimensional nature of the\ninjection barriers, and using Bardeen-Tersoff theory, we derive the appropriate\nform of the Richardson equation that describes such composite barrier; (iii) we\npropose a novel transfer length method (TLM) based SBH extraction methodology,\nto reliably extract SBH by eliminating any confounding effect of temperature\ndependent channel resistance variation; (iv) we derive the Landauer limit of\nthe contact resistance achievable in such devices. A comparison of the limits\nwith the experimentally achieved contact resistance reveals plenty of room for\ntechnological improvements."
    },
    {
        "anchor": "Observation of Strong Coulomb Blockade in Resistively Isolated Tunnel\n  Junctions: We report measurements of the Coulomb-blockade current in resistively\nisolated (R_{Isol} >> h/e^{2}) tunnel junctions for the temperature range 60mK\n$We report measurements of the Coulomb-blockade current in resistively isolated\n($R_{Isol}\\gg h/e^{2})$ tunnel junctions for the temperature range 60mK < T <\n230mK where the charging energy E_{c} is much greater than the thermal energy.\nA zero-bias resistance R_{0} of up to 10^{4}R_{T} (the tunnel resistance of the\nbare junction) is obtained. For eV << E_{c}, the I-V curves for a given\nR_{Isol} scale as a function of V/T, with I \\propto V^{\\alpha (R_{Isol})} over\na range of V. The data agree well with numerical calculations of the tunneling\nrate that include environmental effects.",
        "positive": "Probing Majorana edge states with a flux qubit: A pair of counter-propagating Majorana edge modes appears in chiral p-wave\nsuperconductors and in other superconducting systems belonging to the same\nuniversality class. These modes can be described by an Ising conformal field\ntheory. We show how a superconducting flux qubit attached to such a system\ncouples to the two chiral edge modes via the disorder field of the Ising model.\nDue to this coupling, measuring the back-action of the edge states on the qubit\nallows to probe the properties of Majorana edge modes."
    },
    {
        "anchor": "Coulomb Blockade Fluctuations in Strongly Coupled Quantum Dots: Quantum fluctuations of Coulomb blockade are investigated as a function of\nthe coupling to reservoirs in semiconductor quantum dots. We use fluctuations\nin the distance between peaks $\\Delta N$ apart to characterize both the\namplitude and correlation of peak motion. For strong coupling, peak motion is\ngreatly enhanced at low temperature, but does not show an increase in\npeak-to-peak correlation. These effects can lead to anomalous temperature\ndependence in the Coulomb valleys, similar to behavior ascribed to Kondo\nphysics.",
        "positive": "Electric-field Manipulation of the Lande' g Tensor of Holes in\n  In0.5Ga0.5As/GaAs Self-assembled Quantum Dots: The effect of an electric field on spin precession in In0.5Ga0.5As/GaAs\nself-assembled quantum dots is calculated using multiband real-space\nenvelope-function theory. The dependence of the Lande' g tensor on electric\nfields should permit high-frequency g tensor modulation resonance, as well as\ndirect, nonresonant electric-field control of the hole spin. Subharmonic\nresonances have also been found in g tensor modulation resonance of the holes,\ndue to the strong quadratic dependence of components of the hole g tensor on\nthe electric field."
    },
    {
        "anchor": "Elastic constants of graphene: Comparison of empirical potentials and\n  DFT calculations: The capacity of popular classical interatomic potentials to describe elastic\nproperties of graphene is tested. The Tersoff potential, Brenner reactive\nbond-order potentials REBO-1990, REBO-2000, REBO-2002 and AIREBO as well as\nLCBOP, PPBE-G, ReaxFF-CHO and ReaxFF-C2013 are considered. Linear and\nnon-linear elastic response of graphene under uniaxial stretching is\ninvestigated by static energy calculations. The Young's modulus, Poisson's\nratio and high-order elastic moduli are verified against the reference data\navailable from experimental measurements and ab initio studies. The density\nfunctional theory calculations are performed to complement the reference data\non the effective Young's modulus and Poisson's ratio at small but finite\nelongations. It is observed that for all the potentials considered, the elastic\nenergy deviates remarkably from the simple quadratic dependence already at\nelongations of several percent. Nevertheless, LCBOP provides the results\nconsistent with the reference data and thus realistically describes in-plane\ndeformations of graphene. Reasonable agreement is also observed for the\ncomputationally cheap PPBE-G potential. REBO-2000, AIREBO and REBO-2002 give a\nstrongly non-linear elastic response with a wrong sign of the third-order\nelastic modulus and the corresponding results are very far from the reference\ndata. The ReaxFF potentials drastically overestimate the Poisson's ratio.\nFurthermore, ReaxFF-C2013 shows a number of numerical artefacts at finite\nelongations. The bending rigidity of graphene is also obtained by static energy\ncalculations for large-diameter carbon nanotubes. The best agreement with the\nexperimental and ab initio data in this case is achieved using the REBO-2000,\nREBO-2002 and ReaxFF potentials. Therefore, none of the considered potentials\nadequately describes both in-plane and out-of-plane deformations of graphene.",
        "positive": "High performance bilayer-graphene Terahertz detectors: We report bilayer-graphene field effect transistors operating as THz\nbroadband photodetectors based on plasma-waves excitation. By employing\nwide-gate geometries or buried gate configurations, we achieve a responsivity\n$\\sim 1.2V/W (1.3 mA/W)$ and a noise equivalent power $\\sim 2\\times 10^{-9}\nW/Hz^{-1/2}$ in the 0.29-0.38 THz range, in photovoltage and photocurrent mode.\nThe potential of this technology for scalability to higher frequencies and the\ndevelopment of flexible devices makes our approach competitive for a future\ngeneration of THz detection systems."
    },
    {
        "anchor": "A mono-atomic orbital-based 1D topological crystalline insulator: Topological crystalline insulators (TCIs) are classified by topological\ninvariants defined with respect to the crystalline symmetries of their gapped\nbulk. The bulk-boundary correspondence then links the topological properties of\nthe bulk to robust observables on the edges, e.g., the existence of robust edge\nmodes or fractional charge. In one dimension, TCIs protected by reflection\nsymmetry have been realized in a variety of systems where each unit cell has\nspatially distributed degrees of freedom (SDoF). However, these realizations of\nTCIs face practical challenges stemming from the sensitivity of the resulting\nedge modes to variations in edge termination and to the local breaking of the\nprotective spatial symmetries by inhomogeneity. Here we demonstrate\ntopologically protected edge states in a mono-atomic, orbital-based TCI that\nmitigates both of these issues. By collapsing all SDoF within the unit cell to\na singular point in space, we eliminate the ambiguity in unit cell definition\nand hence remove a prominent source of boundary termination variability. The\ntopological observables are also more tolerant to disorder in the orbital\nenergies. To validate this concept, we experimentally realize a lattice of\nmechanical resonators where each resonator acts as an \"atom\" that harbors two\nkey orbital degrees of freedom having opposite reflection parity. Our\nmeasurements of this system provide direct visualization of the\n$sp$-hybridization between orbital modes that leads to a non-trivial band\ninversion in the bulk. Furthermore, as the spatial width of the resonators is\ntuned, one can drive a transition between a topological and trivial phase. In\nthe future we expect our approach can be extended to realize orbital-based\nobstructed atomic insulators and TCIs in higher dimensions.",
        "positive": "Unusual angular dependence of tunneling magneto-Seebeck effect: We find an unusual angular dependence of the tunneling magneto-Seebeck effect\n(TMS). The conductance shows normally a cosine-dependence with the angle\nbetween the magnetizations of the two ferromagnetic leads. In contrast, the\nangular dependence of the TMS depends strongly on the tunneling magneto\nresistance (TMR) ratio. For small TMR ratios we obtain also a cosine-dependence\nwhereas for very large TMR ratios the angular dependence approaches a step-like\nfunction."
    },
    {
        "anchor": "Evidence for Braggoriton Excitations in Opal Photonic Crystals\n  Infiltrated with Highly Polarizable Dyes: We studied angle-dependent reflectivity spectra of opal photonic crystals\ninfiltrated with cyanine dyes, which are highly polarizable media with very\nlarge Rabi frequency. We show that when resonance conditions between the\nexciton-polariton of the infiltrated dye and Bragg frequencies exist, then the\nBragg stop band decomposes into two reflectivity bands with a semi-transparent\nspectral range in between that is due to light propagation inside the gap\ncaused by the existence of braggoriton excitations. These novel excitations\nresult from the interplay interaction between the Bragg gap with spatial\nmodulation origin and the polariton gap due to the excitons, and may lead to\noptical communication traffic inside the gap of photonic crystals via channel\nwaveguiding.",
        "positive": "Linking Magnon-Cavity Strong Coupling to Magnon-Polaritons through\n  Effective Permeability: Strong coupling in cavity-magnon systems has shown great potential for use in\nspintronics and information processing technologies due to the low damping\nrates and long coherence times. Although such systems are conceptually similar\nto those coupled by magnon-polaritons (MPs), the link between magnon-cavity\ncoupling and MPs has not been explicitly defined. In this work we establish\nsuch a connection by studying the frequency-wavevector dispersion of a strongly\ncoupled magnon-cavity system, using a height-adjustable microwave cavity, and\nby modelling the observed behaviour through the system's effective\npermeability. A polariton gap between the upper and lower coupled modes of the\nmagnon-cavity system is defined, and is seen to be dependent on the system's\neffective filling factor. This gap is equal to the MP polariton gap in the\nlimit where filling factor = 1, corresponding to the removal of the microwave\ncavity. Thus, our work clarifies the connection between magnon-cavity and MP\ncoupling, improving our understanding of magnon-photon interactions in coupled\nsystems."
    },
    {
        "anchor": "Chemical sensing with graphene: A quantum field theory perspective: We studied theoretically the effect of a low concentration of adsorbed polar\nmolecules on the optical conductivity of graphene, within the Kubo linear\nresponse approximation. Our analysis is based on a continuum model\napproximation that includes up to next to nearest neighbors in the pristine\ngraphene effective Hamiltonian, thus extending the field-theoretical analysis\ndeveloped in Refs.[1,2]. Our results show that the conductivity can be\nexpressed in terms of renormalized quasiparticle parameters $\\tilde{v}_F$,\n$\\tilde{M}$ and $\\tilde{\\mu}$ that include the effect of the molecular surface\nconcentration $n_{dip}$ and dipolar moment $\\boldsymbol{\\mathcal{P}}$, thus\nproviding an analytical model for a graphene-based chemical sensor.",
        "positive": "Topological invariants in two-dimensional quasicrystals: We study the topological characterization of the energy gaps in general\ntwo-dimensional quasiperiodic systems consisting of multiple periodicities,\nrepresented by twisted two-dimensional materials. We show that every single gap\nis uniquely characterized by a set of integers, which quantize the area of the\nmomentum space in units of multiple Brillouin zones defined in the redundant\nperiodicities. These integers can be expressed as the second Chern numbers, by\nconsidering an adiabatic charge pumping under a relative slide of different\nperiodicities, and using a formal relationship to the four-dimensional quantum\nHall effect. The integers are independent of commensurability of the multiple\nperiods, and invariant under arbitrary continuous deformations such as a\nrelative rotation of twisted periodicities."
    },
    {
        "anchor": "Computationally efficient Monte Carlo electron transport algorithm for\n  nanostructured thermoelectric material configurations: Monte Carlo statistical ray-tracing methods are commonly employed to simulate\ncarrier transport in nanostructured materials. In the case of a large degree of\nnanostructuring and under linear response (small driving fields), these\nsimulations tend to be computationally overly expensive due to the difficulty\nin gathering the required flux statistics. Here, we present a novel MC\nray-tracing algorithm with computational efficiency of at least an order of\nmagnitude compared to existing algorithms. Our new method, which is a hybrid of\nanalytical Boltzmann transport equation and Monte Carlo uses a reduced number\nof ray-tracing particles, avoids current statistical challenges such as the\nsubtraction of two opposite going fluxes, the application of a driving force\naltogether, and the large simulation time required for low energy carriers. We\ndemonstrate the algorithm's efficiency and power in accurate simulations in\nlarge domain nanostructures with multiple defects. We believe that the new\nmethod we present is indeed more robust and user friendly compared to common\nmethods, and can enable the efficient study of transport in nanostructured\nmaterials under low-field steady-state conditions.",
        "positive": "On-demand electron source with tunable energy distribution: We propose a scheme to manipulate the electron-hole excitation in the voltage\npulse electron source, which can be realized by a voltage-driven Ohmic contact\nconnecting to a quantum hall edge channel. It has been known that the\nelectron-hole excitation can be suppressed via Lorentzian pulses, leading to\nnoiseless electron current. We show that, instead of the Lorentzian pulses,\ndriven via the voltage pulse $V(t) = 2 \\frac{\\hbar}{e}\n\\sqrt{\\frac{\\sqrt{3}}{\\pi} k_{\\rm B} T_h} \\arctanh( \\frac{t - t_0}{t_0} )$ with\nduration $t_0$, the electron-hole excitation can be tuned so that the\ncorresponding energy distribution of the emitted electrons follows the Fermi\ndistribution with temperature $T_{\\rm D} = \\sqrt{ T^2_{\\rm S} + T^2_{\\rm h} }$,\nwith $T_{\\rm S}$ being the electron temperature in the Ohmic contact. Such\nFermi distribution can be established without introducing additional energy\nrelaxation mechanism and can be detected via shot noise thermometry technique,\nmaking it helpful in the study of thermal transport and decoherence in\nmesoscopic system."
    },
    {
        "anchor": "Nanoelectromechanical rotary current rectifier: Nanoelectromechanical systems (NEMS) are devices integrating electrical and\nmechanical functionality on the nanoscale. Because of individual electron\ntunneling, such systems can show rich self-induced, highly non-linear dynamics.\nWe show theoretically that rotor shuttles, fundamental NEMS without intrinsic\nfrequencies, are able to rectify an oscillatory bias voltage over a wide range\nof external parameters in a highly controlled manner, even if subject to the\nstochastic nature of electron tunneling and thermal noise. Supplemented by a\nsimple analytic model, we identify different operational modes of charge\nrectification. Intriguingly, the direction of the current depends sensitively\non the external parameters.",
        "positive": "Half-Metallic Graphene Nanoribbons: Electrical current can be completely spin polarized in a class of materials\nknown as half-metals, as a result of the coexistence of metallic nature for\nelectrons with one spin orientation and insulating for electrons with the\nother. Such asymmetric electronic states for the different spins have been\npredicted for some ferromagnetic metals - for example, the Heusler compounds-\nand were first observed in a manganese perovskite. In view of the potential for\nuse of this property in realizing spin-based electronics, substantial efforts\nhave been made to search for half-metallic materials. However, organic\nmaterials have hardly been investigated in this context even though\ncarbon-based nanostructures hold significant promise for future electronic\ndevice. Here we predict half-metallicity in nanometre-scale graphene ribbons by\nusing first-principles calculations. We show that this phenomenon is realizable\nif in-plane homogeneous electric fields are applied across the zigzag-shaped\nedges of the graphene nanoribbons, and that their magnetic property can be\ncontrolled by the external electric fields. The results are not only of\nscientific interests in the interplay between electric fields and electronic\nspin degree of freedom in solids but may also open a new path to explore\nspintronics at nanometre scale, based on graphene."
    },
    {
        "anchor": "Titanium dioxide synthesized using titanium chloride: Size effect study\n  using Raman and Photoluminescence: Titanium dioxide (TiO2) nanocrystals were prepared by wet chemical method and\ncharacterized by x-ray diffraction (XRD), transmission electron microscopy\n(TEM), Raman scattering (RS) and photoluminescence (PL). The X-ray diffraction\nshows the formation of nanocrytalline TiO2 of average sizes 7 nm and 15 nm for\ntwo samples. The x-ray diffraction, transmission electron microscopy (TEM) and\nRaman scattering shows that the TiO2 nanocrystals has anatase crystal structure\nfor both samples. The PL intensity of the smaller particle is more, which has\nbeen attributed to defects and particle size variation. A modified phonon\nconfinement model with the inclusion of size distribution, a new confinement\nfunction for TiO2 nanocrystals and averaged dispersion curves for most\ndispersion phonon branch (G-X direction) has been used to interpret the size\nvariation of Raman spectra. The obtained Raman peak shift and FWHM agree will\nthe experimental data. Our observations suggest that phonon confinement effects\nare responsible for a significant shift and broadening for the Raman peaks.",
        "positive": "Dephasing Time of Two-Dimensional Holes in GaAs Open Quantum Dots: We report magnetotransport measurements of two-dimensional holes in open\nquantum dots, patterned either as a single-dot or an array of dots, on a GaAs\nquantum well. For temperatures $T$ below 500 mK, we observe signatures of\ncoherent transport, namely, conductance fluctuations and weak antilocalization.\n  From these effects, the hole dephasing time $\\tau_\\phi$ is extracted using\nthe random matrix theory. While $\\tau_\\phi$ shows a $T$-dependence that lies\nbetween $T^{-1}$ and $T^{-2}$, similar to that reported for electrons, its\nvalue is found to be approximately one order of magnitude smaller."
    },
    {
        "anchor": "Model for multi-shot all-thermal all-optical switching in ferromagnets: All optical magnetic switching (AOS) is a recently observed rich and puzzling\nphenomenon that offers promis- ing technological applications. However,\nfundamental understanding of the underlying mechanisms remains elusive. Here we\npresent a new model for multi-shot helicity-dependent AOS in ferromagnetic\nmaterials based on a purely heat-driven mechanism in the presence of Magnetic\nCircular Dichroism (MCD). We predict that AOS should be possible with as little\nas 0.5% of MCD, after a minimum number of laser shots. Finally, we re- produce\nprevious AOS results by simulating the sweeping of a laser beam on an FePtC\ngranular ferromagnetic film.",
        "positive": "Moire miniband features in the angle-resolved photoemission spectra of\n  graphene/hBN heterostructures: We identify features in the angle-resolved photoemission spectra (ARPES)\narising from the periodic pattern characteristic for graphene heterostructure\nwith hexagonal boron nitride (hBN). For this, we model ARPES spectra and\nintensity maps for five microscopic models used previously to describe moire\nsuperlattice in graphene/hBN systems. We show that detailed analysis of these\nfeatures can be used to pin down the microscopic mechanism of the interaction\nbetween graphene and hBN. We also analyze how the presence of a moire-periodic\nstrain in graphene or scattering of photoemitted electrons off hBN can be\ndistinguished from the miniband formation."
    },
    {
        "anchor": "Cross-correlation of two interacting conductors: We calculate the current cross-correlation for two weakly interacting\nmesoscopic conductors. Our derivation is based on the two-particle scattering\nmatrix derived in Goorden and B\\\"uttiker [Phys. Rev. Lett. {\\bf 99}, 146801\n(2007)]. We include the Fermi sea in the leads into the theory and show how to\ncalculate transport quantities and specifically cross-correlations. We focus on\nthe zero-frequency current cross-correlation of two chaotic quantum dots and\ncalculate the magnitude of its fluctuations with the help of Random Matrix\nTheory.",
        "positive": "Impact of AC Magnetic Field on Decoherence of Quantum Dot based Single\n  Spin Qubit System: Quantum dot-based spin qubits are resilient towards charge noise and are\naffected by magnetic noise only. However, environmental interaction leads to\ndecoherence in these qubit systems. The external control parameters are\ndirectly related to the magnitude of decoherence. This in turn limits the range\nof values of those parameters for which operations can be done with high\nfidelity. In this work, using a model of quantum dot spin qubit system, we\ninvestigate the impact of varying ac magnetic fields on suppression of\ndecoherence. We report an increment in the usable range of static magnetic\nfield value using our technique."
    },
    {
        "anchor": "Probing type-II Ising pairing using the spin-mixing parameter: The immunity of the Ising superconductors to external magnetic fields\noriginates from a spin locking of the paired electrons to an intrinsic\nZeeman-like field. The spin-momentum locking in non-centrosymmetric crystalline\nmaterials leads to type-I Ising pairing in which the direction of the intrinsic\nfield can be deduced from the spin expectation values. In centrosymmetric\ncrystals, all the states are spin degenerate due to time reversal symmetry, but\nsplit by the spin-orbit coupling to orbital doublets. The electron spins locked\nto the orbitals can form Ising type-II pairs. We present an efficient approach\nto determine the direction of the intrinsic field using the spin-mixing\nparameter $b^2$. By means of first principles calculations based on the density\nfunctional theory we study monolayer polytype 1T phase transition metal\ndichalcogenide superconductors PdTe$_2$, NbTe$_2$ and TiSe$_2$. We calculate\n$b^2$ for individual Fermi pockets crossing the Fermi energy and provide a\ngeneral picture of possible Ising type-II pairing within the full Brillouin\nzone.",
        "positive": "Orbitronics: Light-induced Orbit Currents in Terahertz Emission\n  Experiments: Orbitronics is based on the use of orbit currents as information carriers. Up\nto now, orbit currents were created from the conversion of charge or spin\ncurrents, and inversely, they could be converted back to charge or spin\ncurrents. Here we demonstrate that orbit currents can also be generated by\nfemtosecond light pulses on Ni. In multilayers associating Ni with oxides and\nnonmagnetic metals such as Cu, we detect the orbit currents by their conversion\ninto charge currents and the resulting terahertz emission. We show that the\norbit currents extraordinarily predominate the light-induced spin currents in\nNi-based systems, whereas only spin currents can be detected with CoFeB-based\nsystems. In addition, the analysis of the time delays of the terahertz pulses\nleads to relevant information on the velocity and propagation of orbit\ncarriers. Our finding of light-induced orbit currents and our observation of\ntheir conversion into charge currents opens new avenues in orbitronics,\nincluding the development of orbitronic terahertz devices."
    },
    {
        "anchor": "Two-dimensional topological superconductivity with antiferromagnetic\n  insulators: Two-dimensional topological superconductivity has attracted great interest\ndue to the emergence of Majorana modes bound to vortices and propagating along\nedges. However, due to its rare appearance in natural compounds, experimental\nrealizations rely on a delicate artificial engineering involving materials with\nhelical states, magnetic fields and conventional superconductors. Here we\nintroduce an alternative path using a class of three-dimensional\nantiferromagnet to engineer a two- dimensional topological superconductor. Our\nproposal exploits the appearance of solitonic states at the interface between a\ntopologically trivial antiferromagnet and a conventional superconductor, which\nrealize a topological superconducting phase when their spectrum is gapped by\nintrinsic spin- orbit coupling. We show that these interfacial states do not\nrequire fine-tuning, but are protected by asymptotic boundary conditions.",
        "positive": "Mapping Phonon Modes from Reduced-Dimensional to Bulk Systems: An algorithm for mapping the true phonon modes of a film, which are defined\nby a two-dimensional (2D) Brillouin zone, to the modes of the corresponding\nbulk material, which are defined by a three-dimensional (3D) Brillouin zone, is\nproposed. The algorithm is based on normal mode decomposition and is inspired\nby the observation that the atomic motions generated by the 2D eigenvectors\nlead to standing-wave-like behaviors in the cross-plane direction. It is\napplied to films between two and ten unit cells thick built from Lennard-Jones\n(LJ) argon, whose bulk is isotropic, and graphene, whose bulk (graphite) is\nanisotropic. For LJ argon, the density of states deviates from that of the bulk\nas the film gets thinner due to phonon frequencies that shift to lower values.\nThis shift is a result of transverse branch splitting due to the film's\nanisotropy and the emergence of a quadratic acoustic branch. As such, while the\nmapping algorithm works well for the thicker LJ argon films, it does not\nperform as well for the thinner films as there is a weaker correspondence\nbetween the 2D and 3D modes. For graphene, the density of states of even the\nthinnest films closely matches that of graphite due to the inherent anisotropy,\nexcept for a small shift at low frequency. As a result, the mapping algorithm\nworks well for all thicknesses of the graphene films, indicating a strong\ncorrespondence between the 2D and 3D modes."
    },
    {
        "anchor": "Joint moments of proper delay times: We calculate negative moments of the $N$-dimensional Laguerre distribution\nfor the orthogonal, unitary, and symplectic symmetries. These moments\ncorrespond to those of the proper delay times, which are needed to determine\nthe statistical fluctuations of several transport properties through\nclassically chaotic cavities, like quantum dots and microwave cavities with\nideal coupling.",
        "positive": "Band Gap of Atomically Precise Graphene Nanoribbons as a Function of\n  Ribbon Length and Termination: We study the band gap of finite $N_A=7$ armchair graphene nanoribbons\n(7-AGNRs) on Au(111) through scanning tunneling microscopy/spectroscopy\ncombined with density functional theory calculations. The band gap of 7-AGNRs\nwith lengths of 6 nm and more is converged to within 0.1 eV of its bulk value\nof 2.3 eV, while the band gap opens by several hundred meV in very short\n7-AGNRs. The termination has a significant effect on the band gap, doubly\nhydrogenated termini yielding a lower band gap than singly hydrogenated ones."
    },
    {
        "anchor": "Revealing the higher-order spin nature of the Hall effect in\n  non-collinear antiferromagnet $\\mathrm{Mn_3Ni_{0.35}Cu_{0.65}N}$: Ferromagnets generate an anomalous Hall effect even without the presence of a\nmagnetic field, something that conventional antiferromagnets cannot replicate\nbut noncollinear antiferromagnets can. The anomalous Hall effect governed by\nthe resistivity tensor plays a crucial role in determining the presence of time\nreversal symmetry and the topology present in the system. In this work we\nreveal the complex origin of the anomalous Hall effect arising in noncollinear\nantiferromagnets by performing Hall measurements with fields applied in\nselected directions in space with respect to the crystalline axes. Our coplanar\nmagnetic field geometry goes beyond the conventional perpendicular field\ngeometry used for ferromagnets and allows us to suppress any magnetic dipole\ncontribution. It allows us to map the in-plane anomalous Hall contribution and\nwe demonstrate a 120$^\\circ$ symmetry which we find to be governed by the\noctupole moment at high fields. At low fields we subsequently discover a\nsurprising topological Hall-like signature and, from a combination of\ntheoretical techniques, we show that the spins can be recast into dipole,\nemergent octupole and noncoplanar effective magnetic moments. These co-existing\norders enable magnetization dynamics unachievable in either ferromagnetic or\nconventional collinear antiferromagnetic materials.",
        "positive": "Electron-Electron Interactions in 2D Semiconductor InSe: Electron-electron interactions (EEIs) in 2D van der Waals structures is one\nof the topics with high current interest in physics. We report the observation\nof a negative parabolic magnetoresistance (MR) in multilayer 2D semiconductor\nInSe beyond the low-field weak localization/antilocalization regime, and\nprovide evidence for the EEI origin of this MR behavior. Further, we analyze\nthis negative parabolic MR and other observed quantum transport signatures of\nEEIs (temperature dependent conductance and Hall coefficient) within the\nframework of Fermi liquid theory and extract the gate voltage tunable Fermi\nliquid parameter $F_0^\\sigma$ which quantifies the electron spin-exchange\ninteraction strength."
    },
    {
        "anchor": "Charge versus energy transfer in atomically-thin graphene-transition\n  metal dichalcogenide van der Waals heterostructures: Van der Waals heterostuctures, made from stacks of two-dimensional materials,\nexhibit unique light-matter interactions and are promising for novel\noptoelectronic devices. The performance of such devices is governed by\nnear-field coupling through, e.g., interlayer charge and/or energy transfer.\nNew concepts and experimental methodologies are needed to properly describe\ntwo-dimensional heterointerfaces. Here, we report on interlayer charge and\nenergy transfer in atomically thin metal (graphene)/semiconductor (transition\nmetal dichalcogenide (TMD, here MoSe$_2$)) heterostructures using a combination\nof photoluminescence and Raman scattering spectroscopies. The photoluminescence\nintensity in graphene/MoSe$_2$ is quenched by more than two orders of magnitude\nand rises linearly with the photon flux, demonstrating a drastically shortened\n($\\sim 1~\\tr{ps}$) room temperature MoSe$_2$ exciton lifetime. Key\ncomplementary insights are provided from analysis of the graphene and MoSe$_2$\nRaman modes, which reveals net photoinduced electron transfer from MoSe$_2$ to\ngraphene and hole accumulation in MoSe$_2$. Remarkably, the steady state Fermi\nenergy of graphene saturates at $290\\pm 15~\\tr{meV}$ above the Dirac point.\nThis behavior is observed both in ambient air and in vacuum and is discussed in\nterms of band offsets and environmental effects. In this saturation regime,\nbalanced photoinduced flows of electrons and holes may transfer to graphene, a\nmechanism that effectively leads to energy transfer. Using a broad range of\nphoton fluxes and diverse environmental conditions, we find that the presence\nof net photoinduced charge transfer has no measurable impact on the near-unity\nphotoluminescence quenching efficiency in graphene/MoSe$_2$. This absence of\ncorrelation strongly suggests that energy transfer to graphene is the dominant\ninterlayer coupling mechanism between atomically-thin TMDs and graphene.",
        "positive": "High-frequency performance of graphene field effect transistors with\n  saturating IV-characteristics: High-frequency performance of graphene field-effect transistors (GFETs) with\nboron-nitride gate dielectrics is investigated. Devices show saturating IV\ncharacteristics and fmax values as high as 34 GHz at 600-nm channel length.\nBias dependence of fT and fmax and the effect of the ambipolar channel on\ntransconductance and output resistance are also examined."
    },
    {
        "anchor": "Al$_2$B$_2$ and AlB$_4$ monolayers: emergence of multiple\n  two-dimensional Dirac nodal line semimetals with novel properties: Topological semimetal phases in two-dimensional (2D) materials have gained\nwidespread interest due to their potential applications in developing nanoscale\ndevices. Despite the prediction of the Dirac/Weyl points in a wide variety of\n2D candidates, materials featuring topological nodal lines are still in great\nscarcity. Herein, we predict two stable thinnest films of aluminum diboride\nwith hyper- and hypo-stoichiometries of Al$_2$B$_2$ and AlB$_4$ as new 2D\nnonmagnetic Dirac nodal line semimetals (NLSMs) which promise to offer many\nnovel features. Our elaborate electronic structure calculations combined with\nanalytical studies reveal that, in addition to the multiple Dirac points, these\n2D configurations host various type-I closed nodal lines (NLs) around the Fermi\nlevel, all of which are semimetal states protected by the time-reversal and\nin-plane mirror symmetries. The most intriguing NL in Al$_2$B$_2$ encloses the\nK point and crosses the Fermi level with a considerable dispersion, thus\nproviding a fresh playground to explore exotic properties in dispersive Dirac\nnodal lines. More strikingly, in the case of 2D superconductor AlB$_4$ which\nexhibits a high transition temperature, we provide the first evidence for a set\nof 2D nonmagnetic open type-II NLs in weak spin-orbit coupling limit,\ncoinciding with closed type-I NLs near the Fermi level. The coexistence of\nsuperconductivity and nontrivial band topology in AlB$_4$ not only makes it a\npromising material to exhibit novel topological superconducting phases, but\nalso the rather large energy dispersion of type-II nodal lines in this\nconfiguration, may offer a distinguished platform for realization of novel\ntopological features in two-dimensional limit.",
        "positive": "Entanglement-symmetry control in a quantum-dot Cooper-pair splitter: The control of nonlocal entanglement in solid state systems is a crucial\ningredient of quantum technologies. We investigate a Cooper-pair splitter based\non a double quantum dot realised in a semiconducting nanowire. In the presence\nof interdot tunnelling the system provides a simple mechanism to develop\nspatial entanglement even in absence of nonlocal coupling with the\nsuperconducting lead. We discuss the possibility to control the symmetry\n(singlet or triplet) of spatially separated, entangled electron pairs taking\nadvantage of the spin-orbit coupling of the nanowire. We also demonstrate that\nthe spin-orbit coupling does not impact over the entanglement purity of the\nnonlocal state generated in the double quantum dot system."
    },
    {
        "anchor": "Chiral ferromagnetism beyond Lifshitz invariants: We consider a contribution $w_{\\text{ch}}$ to the micromagnetic energy\ndensity that is linear with respect to the first spatial derivatives of the\nlocal magnetization direction. For a generalized 2D Rashba ferromagnet, we\npresent a microscopic analysis of this contribution and, in particular,\ndemonstrate that it cannot be expressed through Lifshitz invariants beyond the\nlinear order in the spin-orbit coupling (SOC) strength. Terms in\n$w_{\\text{ch}}$ beyond Lifshitz invariants emerge as a result of spin rotation\nsymmetry breaking caused by SOC. Effects of these terms on the phase diagram of\nmagnetic states and spin-wave dispersion are discussed. Finally, we present a\nclassification of terms in $w_{\\text{ch}}$, allowed by symmetry, for each\ncrystallographic point group.",
        "positive": "Rattling motion of a single atom in a fullerene cage molecule sensed by\n  terahertz spectroscopy: Upon the discovery of the superatom states in endohedral metallofullerenes\n(EMFs), the superatom properties have become attractive, because ultrafast\nmotion of the trapped atom modifies the charge distribution in the fullerene\ncage. However, the observation of ultrafast atom motion in the fullerene cage\nis very challenging, since dynamical processes take place in the terahertz\n(THz) frequency range in a picometer region. Here, we report on the THz\nspectroscopy of single Ce@C82 EMF molecules by using the single molecule\ntransistor geometry. Due to the vibron-assisted tunneling process, two broad\nphotocurrent peaks are observed in the THz spectra and are ascribed to the\nbending and stretching motions of the encapsulated single Ce atom. This work\ndemonstrates that THz spectroscopy using nanogap electrodes can detect a motion\nof a single atom, opening a door to ultrafast THz nanoscience on the\npicometer-scale."
    },
    {
        "anchor": "Gate induced monolayer behavior in twisted bilayer black phosphorus: Optical and electronic properties of black phosphorus strongly depend on the\nnumber of layers and type of stacking. Using first-principles calculations\nwithin the framework of density functional theory, we investigate the\nelectronic properties of bilayer black phosphorus with an interlayer twist\nangle of 90$^\\circ$. These calculations are complemented with a simple\n$\\vec{k}\\cdot\\vec{p}$ model which is able to capture most of the low energy\nfeatures and is valid for arbitrary twist angles. The electronic spectrum of\n90$^\\circ$ twisted bilayer black phosphorus is found to be x-y isotropic in\ncontrast to the monolayer. However x-y anisotropy, and a partial return to\nmonolayer-like behavior, particularly in the valence band, can be induced by an\nexternal out-of-plane electric field. Moreover, the preferred hole effective\nmass can be rotated by 90$^\\circ$ simply by changing the direction of the\napplied electric field. In particular, a +0.4 (-0.4) V/{\\AA} out-of-plane\nelectric field results in a $\\sim$60\\% increase in the hole effective mass\nalong the y (x) axis and enhances the $m^*_{y}/m^*_{x}$ ($m^*_{x}/m^*_{y}$)\nratio as much as by a factor of 40. Our DFT and $\\vec{k}\\cdot\\vec{p}$\nsimulations clearly indicate that the twist angle in combination with an\nappropriate gate voltage is a novel way to tune the electronic and optical\nproperties of bilayer phosphorus and it gives us a new degree of freedom to\nengineer the properties of black phosphorus based devices.",
        "positive": "Magnetic imaging and domain nucleation in CrSBr down to the 2D limit: Recent advancements in 2D materials have revealed the potential of van der\nWaals magnets, and specifically of their magnetic anisotropy that allows\napplications down to the 2D limit. Among these materials, CrSBr has emerged as\na promising candidate, because its intriguing magnetic and electronic\nproperties have appeal for both fundamental and applied research in spintronics\nor magnonics. Here, nano SQUID-on-tip (SOT) microscopy is used to obtain direct\nmagnetic imaging of CrSBr flakes with thicknesses ranging from monolayer (N=1)\nto few-layer (N=5). The ferromagnetic order is preserved down to the monolayer,\nwhile the antiferromagnetic coupling of the layers starts from the bilayer\ncase. For odd layers, at zero applied magnetic field, the stray field resulting\nfrom the uncompensated layer is directly imaged. The progressive spin\nreorientation along the out-of-plane direction (hard axis) is also measured\nwith a finite applied magnetic field, allowing to evaluate the anisotropy\nconstant, which remains stable down to the monolayer and is close to the bulk\nvalue. Finally, by selecting the applied magnetic field protocol, the formation\nof N\\'eel magnetic domain walls is observed down to the single layer limit."
    },
    {
        "anchor": "Exchange Field-Mediated Magnetoresistance in the Correlated Insulator\n  Phase of Be Films: We present a study of the proximity effect between a ferromagnet and a\nparamagnetic metal of varying disorder. Thin beryllium films are deposited onto\na 5 nm-thick layer of the ferromagnetic insulator EuS. This bilayer arrangement\ninduces an exchange field, $H_{ex}$, of a few tesla in low resistance Be films\nwith sheet resistance $R\\ll R_Q$, where $R_Q=h/e^2$ is the quantum resistance.\nWe show that $H_{ex}$ survives in very high resistance films and, in fact,\nappears to be relatively insensitive to the Be disorder. We exploit this fact\nto produce a giant low-field magnetoresistance in the correlated insulator\nphase of Be films with $R\\gg R_Q$.",
        "positive": "Tunable magnetoresistance behavior in suspended graphitic multilayers\n  through ion implantation: We report a tunable magnetoresistance (MR) behavior in suspended graphitic\nmultilayers through point defect engineering by ion implantation. We find that\nion implantation drastically changes the MR behavior: the linear positive MR in\npure graphitic multilayers transforms into a negative MR after introducing\nsignificant short-range disorders (implanted boron or carbon atoms), consistent\nwith recent non-Markovian transport theory. Our experiments suggest the\nimportant role of the non-Markovian process in the intriguing MR behavior for\ngraphitic systems, and open a new window for understanding transport phenomena\nbeyond the Drude-Boltzmann approach and tailoring the electronic properties of\ngraphitic layers."
    },
    {
        "anchor": "Role of Noise in Nanostructure Formation: A Theoretical Investigation of\n  Quantum Dots and Quantum Dot Molecules: We theoretically model the formation of quantum dots(QDs) and quantum dot\nmolecules(QDMs) in silicon germanium heteroepitaxy by explicitly incorporating\nthe role of noise in a continuum theory for surface evolution in molecular beam\nepitaxy. Using the connection between flux and noise, we explain how changing\nflux can lead to a transition from QD to QDM formation, as seen in experiments.\nIn these systems we show a dual role of noise in nanostructure growth; one\nwhere it promotes formation of QDMs via pit nucleation, and another where it\ncurtails QDM formation due to stochastic effects.",
        "positive": "Double layer two-dimensional electron systems: Probing the transition\n  from weak to strong coupling with Coulomb drag: Frictional drag measurements revealing anomalously large dissipation at the\ntransition between the weakly- and strongly-coupled regimes of a bilayer\ntwo-dimensional electron system at total Landau level filling factor $\\nu_T =1$\nare reported. This result suggests the existence of fluctuations, either static\nor dynamic, near the phase boundary separating the quantized Hall state at\nsmall layer separations from the compressible state at larger separations.\nInterestingly, the anomalies in drag seem to persist to larger layer\nseparations than does interlayer phase coherence as detected in tunneling."
    },
    {
        "anchor": "Vibrational Enhancement of the Effective Donor - Acceptor Coupling: The paper deals with a simple three sites model for charge transfer phenomena\nin an one-dimensional donor (D) - bridge (B) - acceptor (A) system coupled with\nvibrational dynamics of the B site. It is found that in a certain range of\nparameters the vibrational coupling leads to an enhancement of the effective\ndonor - acceptor electronic coupling as a result of the formation of the\npolaron on the B site. This enhancement of the charge transfer efficiency is\nmaximum at the resonance, where the effective energy of the fluctuating B site\ncoincides with the donor (acceptor) energy.",
        "positive": "Spin transverse force on spin current in an electric field: As a relativistic quantum mechanical effect, it is shown that the electric\nfield exerting a transverse force on an electron spin 1/2 only if the electron\nis moving and the spin is polarized along the electric field. The spin force,\nanalogue to the Lorentz for on an electron charge in a magnetic field, is\nperpendicular to the electric field and the spin current polarized anong the\nelectric field. This spin-dependent force can be used to understand the\nzitterbewegung of electron wave packet with spin-orbit coupling and is relevant\nto the generation of the charge Hall effect driven by the spin current in\nsemiconductors."
    },
    {
        "anchor": "Artificial DNA Lattice Fabrication by Non-Complementarity and\n  Geometrical Incompatibility: Fabrication of DNA nanostructures primarily follows two fundamental rules.\nFirst, DNA oligonucleotides mutually combine by Watson-Crick base pairing rules\nbetween complementary base sequences. Second, the geometrical compatibility of\nthe DNA oligonucleotide must match for lattices to form. Here we present a\nfabrication scheme of DNA nanostructures with non-complementary and/or\ngeometrically incompatible DNA oligonucleotides, which contradicts conventional\nDNA structure creation rules. Quantitative analyses of DNA lattice sizes were\ncarried out to verify the unfavorable binding occurrences which correspond to\nerrors in algorithmic self-assembly. Further studies of these types of bindings\nmay shed more light on the exact mechanisms at work in the self-assembly of DNA\nnanostructures.",
        "positive": "Geometry of Landau orbits in the absence of rotational symmetry: The integer quantum Hall effect (IQHE) is usually modeled using\nGalilean-invariant or rotationally-invariant Landau levels. However, these are\nnot generic symmetries of electrons moving in a crystalline background, even in\nthe low-density continuum limit. We present a treatment of the IQHE which\nabandons the Galilean dispersion relation while keeping inversion symmetry. We\ndefine an emergent metric $g^n_{ab}$ for each Landau level with a reformulation\nof the Hall viscosity. The metric is then used to define a guiding-center\ncoherent state and the wavefunctions are holomorphic functions of $z^*$ times a\nGaussian. By numerically studying cases with quartic dispersion, we show that\nthe number of the zeroes of the wavefunction encircled by the semiclassical\norbit, denoted by $n$, defines a \"topological spin\" $s_n$ by\n$s_n=n+\\frac{1}{2}$, with its original definition as an \"intrinsic angular\nmomentum\" no longer valid without rotational symmetry. At the end of the paper\nwe show our results for the density and current responses which differentiate\nbetween diagonal and Landau-level-mixing terms. In conclusion, this treatment\nextracts topological information without resort to Galilean or rotational\nsymmetry, and also reveals more generic geometric structures."
    },
    {
        "anchor": "Collective Excitations, NMR, and Phase Transitions in Skyrme Crystals: At Landau level filling factors near nu =1, quantum Hall ferromagnets form a\nSkyrme crystal state with quasi-long-range translational and non-collinear\nmagnetic order. We develop an effective low energy theory which explains the\npresence in these systems of magnetic excitations at low energies below the\nLarmor gap (Delta) and which predicts a dramatic enhancement of the nuclear\nspin relaxation rate by a factor of 1000. The effective theory predicts a rich\nset of quantum and classical phase transitions. Based in part on accurate\ntime-dependent Hartree-Fock calculations of the ordered state collective\nexcitation spectrum, we discuss aspects of the T-nu-Delta crystal phase\ndiagram.",
        "positive": "Non-equilibrium inelastic electronic transport: Polarization effects and\n  vertex corrections to the self-consistent Born approximation: We study the effect of electron-vibron interactions on the inelastic\ntransport properties of single-molecule nanojunctions. We use the\nnon-equilibrium Green's functions technique and a model Hamiltonian to\ncalculate the effects of second-order diagrams (double-exchange DX and\ndressed-phonon DPH diagrams) on the electron-vibration interaction and consider\ntheir effects across the full range of parameter space. The DX diagram,\ncorresponding to a vertex correction, introduces an effective dynamical\nrenormalization of the electron-vibron coupling in both the purely inelastic\nand the inelastic-resonant features of the IETS. The purely inelastic features\ncorrespond to an applied bias around the energy of a vibron, while the\ninelastic-resonant features correspond to peaks (resonance) in the conductance.\nThe DPH diagram affects only the inelastic resonant features. We also discuss\nthe circumstances in which the second-order diagrams may be approximated in the\nstudy of more complex model systems."
    },
    {
        "anchor": "Multistep Bloch-line-mediated Walker breakdown in ferromagnetic strips: A well-known feature of magnetic field driven dynamics of domain walls in\nferromagnets is the existence of a threshold driving force at which the\ninternal magnetization of the domain wall starts to precess -- a phenomenon\nknown as the Walker breakdown -- resulting in an abrupt drop of the domain wall\npropagation velocity. Here, we report on micromagnetic simulations of magnetic\nfield driven domain wall dynamics in thin ferromagnetic strips with\nperpendicular magnetic anisotropy which demonstrate that in wide enough strips\nWalker breakdown is a multistep process: It consists of several distinct\nvelocity drops separated by short linear parts of the velocity vs field curve.\nThese features originate from the repeated nucleation, propagation and\nannihilation of an increasing number of Bloch lines within the domain wall as\nthe driving field magnitude is increased. This mechanism arises due to\nmagnetostatic effects breaking the symmetry between the two ends of the domain\nwall.",
        "positive": "Optical spectroscopy of interlayer coupling in artificially stacked MoS2\n  layers: We perform an optical spectroscopy study to investigate the properties of\ndifferent artificial MoS$_2$ bi- and trilayer stacks created from individual\nmonolayers by a deterministic transfer process. These twisted bi- and trilayers\ndiffer from the common 2H stacking in mineral MoS$_2$ in the relative stacking\nangle of adjacent layers and the interlayer distance. The combination of Raman\nspectroscopy, second-harmonic-generation microscopy and photoluminescence\nmeasurements allows us to determine the degree of interlayer coupling in our\nsamples. We find that even for electronically decoupled artificial structures,\nwhich show the same valley polarization degree as the constituent MoS$_2$\nmonolayers at low temperatures, there is a resonant energy transfer between\nindividual layers which acts as an effective luminescence quenching mechanism."
    },
    {
        "anchor": "Transport spectroscopy of ultraclean tunable band gaps in bilayer\n  graphene: The importance of controlling both the charge carrier density and the band\ngap of a semiconductor cannot be overstated, as it opens the doors to a wide\nrange of applications, including, e.g., highly-tunable transistors,\nphotodetectors, and lasers. Bernal-stacked bilayer graphene is a unique\nvan-der-Waals material that allows tuning the band gap by an out-of-plane\nelectric field. Although the first evidence of the tunable gap was already\nfound ten years ago, it took until recent to fabricate sufficiently clean\nheterostructures where the electrically induced gap could be used to fully\nsuppress transport or confine charge carriers. Here, we present a detailed\nstudy of the tunable band gap in gated bilayer graphene characterized by\ntemperature-activated transport and finite-bias spectroscopy measurements. The\nlatter method allows comparing different gate materials and device\ntechnologies, which directly affects the disorder potential in bilayer\ngraphene. We show that graphite-gated bilayer graphene exhibits extremely low\ndisorder and as good as no subgap states resulting in ultraclean tunable band\ngaps up to 120 meV. The size of the band gaps are in good agreement with theory\nand allow complete current suppression making a wide range of semiconductor\napplications possible.",
        "positive": "Projected equations of motion approach to hybrid quantum/classical\n  dynamics in dielectric-metal composites: We introduce a hybrid method for dielectric-metal composites that describes\nthe dynamics of the metallic system classically whilst retaining a quantum\ndescription of the dielectric. The time-dependent dipole moment of the\nclassical system is mimicked by the introduction of projected equations of\nmotion (PEOM) and the coupling between the two systems is achieved through an\neffective dipole-dipole interaction. To benchmark this method, we model a test\nsystem (semiconducting quantum dot-metal nanoparticle hybrid). We begin by\nexamining the energy absorption rate, showing agreement between the PEOM method\nand the analytical rotating wave approximation (RWA) solution. We then\ninvestigate population inversion and show that the PEOM method provides an\naccurate model for the interaction under ultrashort pulse excitation where the\ntraditional RWA breaks down."
    },
    {
        "anchor": "Pseudo-electromagnetic fields in topological semimetals: Dirac and Weyl semimetals, materials where electrons behave as relativistic\nfermions, react to position- and time-dependent perturbations, such as strain,\nas if emergent electromagnetic fields were applied. Since they differ from\nexternal electromagnetic fields in their symmetries and phenomenology they are\ncalled pseudo-electromagnetic fields, and enable a simple and unified\ndescription of a variety of inhomogeneous systems involving topological\nsemimetals. We review the different physical ways to create effective\npseudo-fields, their observable consequences as well as their similarities and\ndifferences compared to electromagnetic fields. Among these difference is their\neffect on quantum anomalies, the absence of a classical symmetry in the quantum\ntheory, which we revisit from a quantum field theory and a semiclassical\nviewpoint. We conclude with predicted observable signatures of the\npseudo-fields and the nascent experimental status.",
        "positive": "Plasmonics in the visible domain for a one-dimensional truncated\n  photonic crystal terminated by graphene: sensing beyond Dirac point's\n  approximation: Visible surface plasmon resonances (SPRs) could be excited by TE wave\npolarization in one-dimensional photonic crystals (PCs) coated by a graphene\nlayer under the Kretschmann configuration. In this work, the plasmonic Bloch\nwave properties beyond Dirac points in a one-dimensional graphene-based\nphotonic sensing structure have been numerically studied. We demonstrate that\nemergent plasmonic dips in the reflectance spectra of the suggested photonic\ndevice in the visible region exhibit tunable characteristics upon modulation of\nthe chemical potential and the hopping parameter. The sensitivity of the sensor\nin the visible domain has been numerically evaluated and also was compared with\nthose considering the surface plasmon resonances in the terahertz regime."
    },
    {
        "anchor": "Nature of excitons bound to inversion domain boundaries: Origin of the\n  3.45-eV luminescence lines in spontaneously formed GaN nanowires on Si(111): We investigate the 3.45-eV luminescence band of spontaneously formed GaN\nnanowires on Si(111) by photoluminescence and cathodoluminescence spectroscopy.\nThis band is found to be particularly prominent for samples synthesized at\ncomparatively low temperatures. At the same time, these samples exhibit a\npeculiar morphology, namely, isolated long nanowires are interspersed within a\ndense matrix of short ones. Cathodoluminescence intensity maps reveal the\n3.45-eV band to originate primarily from the long nanowires. Transmission\nelectron microscopy shows that these long nanowires are either Ga polar and are\njoined by an inversion domain boundary with their short N-polar neighbors, or\nexhibit a Ga-polar core surrounded by a N-polar shell with a tubular inversion\ndomain boundary at the core/shell interface. For samples grown at high\ntemperatures, which exhibit a uniform nanowire morphology, the 3.45-eV band is\nalso found to originate from particular nanowires in the ensemble and thus\npresumably from inversion domain boundaries stemming from the coexistence of N-\nand Ga-polar nanowires. For several of the investigated samples, the 3.45-eV\nband splits into a doublet. We demonstrate that the higher-energy component of\nthis doublet arises from the recombination of two-dimensional excitons free to\nmove in the plane of the inversion domain boundary. In contrast, the\nlower-energy component of the doublet originates from excitons localized in the\nplane of the inversion domain boundary. We propose that this in-plane\nlocalization is due to shallow donors in the vicinity of the inversion domain\nboundaries.",
        "positive": "Electron transfer through a multiterminal quantum ring: magnetic forces\n  and elastic scattering effects: We study electron transport through a semiconductor quantum ring with one\ninput and two output terminals for an elastic scatterer present within one of\nthe arms of the ring. We demonstrate that the scatterer not only introduces\nasymmetry in the transport probability to the two output leads but also reduces\nthe visibility of the Aharonov-Bohm conductance oscillations. This reduction\noccurs in spite of the phase coherence of the elastic scattering and is due to\ninterruption of the electron circulation around the ring by the potential\ndefect. The results are in a qualitative agreement with a recent experiment by\nStrambini et al. [Phys. Rev. B {\\bf 79}, 195443 (2009)]. We also indicate that\nthe magnetic symmetry of the sum of conductance of both the output leads as\nobtained in the experiment can be understood as resulting from the invariance\nof backscattering to the input lead with respect to the magnetic field\norientation."
    },
    {
        "anchor": "Fast initialization of the spin state of an electron in a quantum dot in\n  the Voigt configuration: We consider the initialization of the spin-state of a single electron trapped\nin a self-assembled quantum dot via optical pumping of a trion level. We show\nthat with a magnetic field applied perpendicular to the growth direction of the\ndot, a near-unity fidelity can be obtained in a time equal to a few times the\ninverse of the spin-conserving trion relaxation rate. This method is several\norders-of-magnitude faster than with the field aligned parallel, since this\nconfiguration must rely on a slow hole spin-flip mechanism. This increase in\nspeed does result in a limit on the maximum obtainable fidelity, but we show\nthat for InAs dots, the error is very small.",
        "positive": "Numerical Simulation of Two Dimensional Electron Transport in a\n  Circularly Symmetric Cylindrical Nanostructure using Wigner Function Methods: We have constructed a lattice Wigner-Weyl code that generalizes the\nBuot-Jensen algorithm to the calculation of electron transport in\ntwo-dimensional circular-cylindrically symmetric structures, where the Wigner\nfunction equation is solved self-consistently with the Poisson equation. Almost\nall of the numerical simulations to date have dealt with the restriction of the\nproblem to one dimensional transport. In real devices, electrons are not\nconfined to a single dimension and the coulombic potential is fully present and\nfelt in three dimensions. We show the derivation of the 2D equation in\ncylindrical coordinates as well as approximations employed in the calculation\nof the four-dimensional convolution integral of the Wigner function and the\npotential. We work under the assumption that longitudinal transport is more\ndominant than radial transport and employ parallel processing techniques. The\ntotal transport is calculated in two steps: (1) transport the particles in the\nlongitudinal direction in each shell separately, then (2) each shell exchanges\nparticles with its nearest neighbor. Most of this work is concerned with the\nformer step: A 1D space and 2D momentum transport problem. Time evolution\nsimulations based on these method are presented for three different cases. Each\ncase lead to numerical results consistent with expectations. Discussions of\nfuture improvements are discussed."
    },
    {
        "anchor": "A Two Qubit Logic Gate in Silicon: Quantum computation requires qubits that can be coupled and realized in a\nscalable manner, together with universal and high-fidelity one- and two-qubit\nlogic gates \\cite{DiVincenzo2000, Loss1998}. Strong effort across several\nfields have led to an impressive array of qubit realizations, including trapped\nions \\cite{Brown2011}, superconducting circuits \\cite{Barends2014}, single\nphotons\\cite{Kok2007}, single defects or atoms in diamond \\cite{Waldherr2014,\nDolde2014} and silicon \\cite{Muhonen2014}, and semiconductor quantum dots\n\\cite{Veldhorst2014}, all with single qubit fidelities exceeding the stringent\nthresholds required for fault-tolerant quantum computing \\cite{Fowler2012}.\nDespite this, high-fidelity two-qubit gates in the solid-state that can be\nmanufactured using standard lithographic techniques have so far been limited to\nsuperconducting qubits \\cite{Barends2014}, as semiconductor systems have\nsuffered from difficulties in coupling qubits and dephasing \\cite{Nowack2011,\nBrunner2011, Shulman2012}. Here, we show that these issues can be eliminated\naltogether using single spins in isotopically enriched silicon\\cite{Itoh2014}\nby demonstrating single- and two-qubit operations in a quantum dot system using\nthe exchange interaction, as envisaged in the original Loss-DiVincenzo proposal\n\\cite{Loss1998}. We realize CNOT gates via either controlled rotation (CROT) or\ncontrolled phase (CZ) operations combined with single-qubit operations. Direct\ngate-voltage control provides single-qubit addressability, together with a\nswitchable exchange interaction that is employed in the two-qubit CZ gate. The\nspeed of the two-qubit CZ operations is controlled electrically via the\ndetuning energy and we find that over 100 two-qubit gates can be performed\nwithin a two-qubit coherence time of 8 \\textmu s, thereby satisfying the\ncriteria required for scalable quantum computation.",
        "positive": "Spontaneous interlayer exciton coherence in quantum Hall bilayers at\n  nu=1 and nu=2: a tutorial: This tutorial paper reviews some of the physics of quantum Hall bilayers with\na focus on the case where there is low or zero tunnelling between the two\nlayers. We describe the interlayer coherent states at filling factors nu=1 and\nnu=2 as exciton condensates and discuss some of the theory associated with\nthese states."
    },
    {
        "anchor": "Realization of quantum diffraction of a thermal flux: The first evidence of the dc Josephson effect dates back to 1963 when J. S.\nRowell measured the diffraction pattern of the critical current flowing through\na single superconducting tunnel junction subjected to an in-plane magnetic\nfield. Interference of Josephson currents through two tunnel junctions\nconnected in parallel was achieved one year later leading to the first ever\nsuperconducting quantum interferometer. The latter, together with Rowell's\nobservations, constituted the unequivocal demonstration of the Josephson\nsupercurrent-phase relation. Yet, the Josephson effect has further profound\nimplications going beyond electrical transport, as the interplay between the\nCooper condensate and unpaired electrons provides thermal flow through the\njunction with phase coherence as well. Here we report the first demonstration\nof quantum diffraction of a heat flux showing that a temperature-biased single\nJosephson junction is exploited as a diffractor for thermal currents.\nSpecifically, thermal diffraction manifests itself with a peculiar modulation\nof the electron temperature in a small metallic electrode nearby-contacted to\nthe junction when sweeping the magnetic flux $\\Phi$. Remarkably, the observed\ntemperature dependence exhibits $\\Phi$-symmetry and a clear reminiscence with a\nFraunhofer-like modulation pattern, as expected fingerprints for a quantum\ndiffraction phenomenon. Our results confirm a pristine prediction of quantum\nheat transport and, joined with double-junction heat interferometry\ndemonstrated in Nature 492, 401 (2012), exemplify the complementary and\nconclusive proof of the existence of phase-dependent thermal currents in\nJosephson-coupled superconductors. This approach combined with well-known\nmethods for phase-biasing superconducting circuits provides with a novel tool\nfor mastering heat fluxes at the nanoscale.",
        "positive": "Melting of Wigner crystal in high-mobility $n$-GaAs/AlGaAs\n  heterostructures at filling factors $0.18 > \u03bd> 0.125$: Acoustic studies: Using acoustic methods the complex high-frequency conductance of\nhigh-mobility $n$-GaAs/AlGaAs heterostructures was determined in magnetic\nfields 12$\\div$18~T. Based on the observed frequency and temperature\ndependences we conclude that in the investigated magnetic field range and at\nsufficiently low temperatures, $T \\lesssim 200$~mK, the electron system forms a\nWigner crystal deformed due to pinning by disorder. At some temperature, which\ndepends on the electron filling factor, the temperature dependences of both\ncomponents of the complex conductance get substantially changed. We have\nascribed this rapid change of the conduction mechanism to melting of the Wigner\ncrystal and study the dependence of the so-defined melting temperature on the\nelectron filling factor."
    },
    {
        "anchor": "Negative Quantum Capacitance of Carbon Nanotube Field-Effect Transistors: Atomistic density functional theory (DFT) calculations of the capacitance\nbetween a metallic cylindric gate and a carbon nanotube (CNT) are reported.\nResults stressing the predominant effect of quantum capacitance in limiting or\neven enhancing screening properties of the CNT are shown. Other contributions\nto the quantum capacitance beyond the electronic density of state (DOS) are\npointed out. Negative values of the quantum capacitance are obtained for\nlow-density systems, which correspondingly over-screen the gate field. This\nunconventional behavior of the quantum capacitance is related to the\npredominance of the exchange contribution in the total electronic energy of the\nCNT.",
        "positive": "Position-dependent mass effects in the electronic transport of\n  two-dimensional quantum systems: In this work, we investigate the electronic transport properties of curved\ntwo-dimensional quantum systems with a position-dependent mass (PDM). We found\nthe Schr\\\"odinger equation for a general surface following the da Costa\napproach, obtaining the geometrical potential for systems with PDM. We obtained\nexpressions for the transmittance and reflectance for a general surface of\nrevolution. As a first application of the general results obtained here, we\ninvestigate the transport properties of deformed nanotubes, since the variation\nof the effective mass with the radius of the nanotubes has been dis-considered\nin previous studies of this system and experimentally a change of the effective\nmass is observed for different radii. We found that the inclusion of the\nposition-dependent mass, particularly a radial change in the mass distribution,\ncan induce a significant change in the transport properties of the system,\nwhich reveals that the transport properties of two dimensional quantum systems\nare sensitive to the PDM and when modeling electronic transport in surfaces\nthis effects should be considered."
    },
    {
        "anchor": "Dynamics of Polar Skyrmion Bubbles under Electric Fields: Room-temperature polar skyrmion bubbles that are recently found in oxide\nsuperlattice, have received enormous interests for their potential applications\nin nanoelectronics due to the nanometer size, emergent chirality, and negative\ncapacitance. For practical applications, the ability to controllably manipulate\nthem by using external stimuli is prerequisite. Here, we study the dynamics of\nindividual polar skyrmion bubbles at the nanoscale by using in situ biasing in\na scanning transmission electron microscope. The reversible electric\nfield-driven phase transition between topological and trivial polar states are\ndemonstrated. We create, erase and monitor the shrinkage and expansion of\nindividual polar skyrmions. We find that their transition behaviors are\nsubstantially different from that of magnetic analogue. The underlying\nmechanism is discussed by combing with the phase-field simulations. The\ncontrollable manipulation of nanoscale polar skyrmions allows us to tune the\ndielectric permittivity at atomic scale and detailed knowledge of their phase\ntransition behaviors provides fundamentals for their applications in\nnanoelectronics.",
        "positive": "Intermodulation spectroscopy as an alternative to pump-probe for the\n  measurement of fast dynamics at the nanometer scale: We present an alternative approach to pump-probe spectroscopy for measuring\nfast charge dynamics with an atomic force microscope (AFM). Our approach is\nbased on coherent multifrequency lock-in measurement of the intermodulation\nbetween a mechanical drive and an optical or electrical excitation. In response\nto the excitation, the charge dynamics of the sample is reconstructed by\nfitting a theoretical model to the measured frequency spectrum of the\nelectrostatic force near resonance of the AFM cantilever. We discuss the time\nresolution, which in theory is limited only by the measurement time, but in\npractice is of order one nanosecond for standard cantilevers and imaging\nspeeds. We verify the method with simulations and demonstrate it with a control\nexperiment, achieving a time resolution of $20~\\mathrm{ns}$ in ambient\nconditions, limited by thermal noise."
    },
    {
        "anchor": "Theory of Graphene-based Plasmonic Switch: We have theoretically studied a graphene-based plasmonic waveguide, which can\ngate the transmission of a surface plasmon polariton (SPP) localized at the\ngraphene-semiconductor interface. When a gate voltage is applied above a\ncertain critical value, the charge density modulation in the quasi\ntwo-dimensional electron gas formed in the inversion layer can induce a local\nplasma resonance. Since the local plasma resonance is strongly coupled to the\nSPP, it can suppress the transmission of the SPP. By calculating the\npropagation length of the SPP with varying gate voltage, we have obtained the\nsharp switching line shape. We have demonstrated that the wavelength of the SPP\ncan be reduced below ~1/100 of that of an incident light and the propagation\nlength of the SPP can be significantly reduced by a factor of ~15 upon\nswitching. This ensures that our plasmonic waveguide can operate effectively as\na plasmonic switch for the SPP.",
        "positive": "Probing breakdown of topological protection: Filling-factor-dependent\n  evolution of robust quantum Hall incompressible phases: The integer quantum Hall (QH) effects characterized by topologically\nquantized and nondissipative transport are caused by an electrically insulating\nincompressible phase that prevents backscattering between chiral metallic\nchannels. We probed the incompressible area susceptible to the breakdown of\ntopological protection using a scanning gate technique incorporating\nnonequilibrium transport. The obtained pattern revealed the filling-factor\n($\\nu$)-dependent evolution of the microscopic incompressible structures\nlocated along the edge and in the bulk region. We found that these specific\nstructures, respectively attributed to the incompressible edge strip and bulk\nlocalization, show good agreement in terms of $\\nu$-dependent evolution with a\ncalculation of the equilibrium QH incompressible phases, indicating the\nrobustness of the QH incompressible phases under the nonequilibrium condition.\nFurther, we found that the $\\nu$ dependency of the incompressible patterns is,\nin turn, destroyed by a large imposed current during the deep QH effect\nbreakdown. These results demonstrate the ability of our method to image the\nmicroscopic transport properties of a topological two-dimensional system."
    },
    {
        "anchor": "Sub-amorphous thermal conductivity in amorphous heterogeneous\n  nanocomposites: Pure amorphous solids are traditionally considered to set the lower bound of\nthermal conductivity due to their disordered atomic structure that impedes\nvibrational energy transport. However, the lower limits for thermal\nconductivity in heterogeneous amorphous solids and the physical mechanisms\nunderlying these limits remain unclear. Here, we use equilibrium molecular\ndynamics to show that an amorphous SiGe nanocomposite can possess thermal\nconductivity substantially lower than those of the amorphous Si and Ge\nconstituents. Normal mode analysis indicates that the presence of the Ge\ninclusion localizes vibrational modes with frequency above the Ge cutoff in the\nSi host, drastically reducing their ability to transport heat. This observation\nsuggests a general route to achieve exceptionally low thermal conductivity in\nfully dense solids by restricting the vibrational density of states available\nfor transport in heterogeneous amorphous nanocomposites.",
        "positive": "Dirac electrons and domain walls: a realization in junctions of\n  ferromagnets and topological insulators: We study a system of Dirac electrons with finite density of charge carriers\ncoupled to an external electromagnetic field in two spatial dimensions, with a\ndomain wall (DW) mass term. The interface between a thin-film ferromagnet and a\nthree-dimensional topological insulator provides a condensed-matter realization\nof this model, when an out-of-plane domain wall magnetization is coupled to the\nTI surface states. We show how, for films with very weak intrinsic in-plane\nanisotropies, the torque generated by the edge electronic current flowing along\nthe DW competes with an effective in-plane anisotropy energy, induced by\nquantum fluctuations of the chiral electrons bound to the wall, in a mission to\ndrive the internal angle of the DW from a Bloch configuration towards a N\\'eel\nconfiguration. Both the edge current and the induced anisotropy contribute to\nstabilize the internal angle, so that for weak intrinsic in-plane anisotropies\nDW motion is still possible without suffering from an extremely early Walker\nbreakdown."
    },
    {
        "anchor": "Thin InSb layers with metallic gratings: a novel platform for\n  spectrally-selective THz plasmonic sensing: We present a computational study of terahertz optical properties of a\ngrating-coupled plasmonic structure based on micrometer-thin InSb layers. We\nfind two strong absorption resonances that we interpret as standing surface\nplasmon modes and investigate their dispersion relations, dependence on InSb\nthickness, and the spatial distribution of the electric field. The observed\nsurface plasmon modes are well described by a simple theory of the air/InSb/air\ntrilayer. The plasmonic response of the grating/InSb structure is highly\nsensitive to the dielectric environment and the presence of an analyte (e.g.,\nlactose) at the InSb interface, which is promising for terahertz plasmonic\nsensor applications. We determine the sensor sensitivity to be 7200 nm per\nrefractive index unit (or 0.06 THz per refractive index unit). The lower\nsurface plasmon mode also exhibits a splitting when tuned in resonance with the\nvibrational mode of lactose at 1.37 THz. We propose that such interaction\nbetween surface plasmon and vibrational modes can be used as the basis for a\nnew sensing modality that allows the detection of terahertz vibrational\nfingerprints of an analyte.",
        "positive": "Atomically-precise Vacancy-assembled Quantum Antidots: Patterning antidots (\"voids\") into well-defined antidot lattices creates an\nintriguing class of artificial structures for the periodic modulation of 2D\nelectron systems, leading to anomalous transport properties and exotic quantum\nphenomena as well as enabling the precise bandgap engineering of 2D materials\nto address technological bottleneck issues. However, realizing such\natomic-scale quantum antidots (QADs) is infeasible by current nanolithographic\ntechniques. Here, we report an atomically-precise bottom-up fabrication of a\nseries of atomic-scale QADs with elegantly engineered quantum states through a\ncontrollable assembly of a chalcogenide single vacancy (SV) in 2D PtTe2, a\ntype-II Dirac semimetal. Te SVs as atomic-scale \"antidots\" undergo thermal\nmigration and assembly into highly-ordered SV lattices spaced by a single Te\natom, reaching the ultimate downscaling limit of antidot lattices. Increasing\nthe number of SVs in QADs strengthens the cumulative repulsive potential and\nconsequently enhances collective interference of multiple-pocket scattered\nquasiparticles inside QADs, creating multi-level quantum hole states with\ntunable gap from telecom to far-infrared regime. Moreover, precisely engineered\nquantum hole states of QADs are symmetry-protected and thus survive upon\natom-by-atom oxygen substitutional doping. Therefore, SV-assembled QADs exhibit\nunprecedented robustness and property tunability, which not only holds the key\nto their future applications but also embody a wide variety of material\ntechnologies."
    },
    {
        "anchor": "Characteristic length scales from entanglement dynamics in\n  electric-field-driven tight-binding chains: We study entanglement dynamics in the nearest-neighbour fermionic chain that\nis subjected to both DC and AC electric fields. The dynamics gives the well\nknown Bloch oscillations in the DC field case provided that the system size is\nlarger than the Bloch length whereas in the AC field case the entropy is\nbounded and oscillates with the driving frequency at the points of dynamical\nlocalization, and has a logarithmic growth at other points. A combined AC + DC\nfield yields super Bloch oscillations for the system size larger than the super\nBloch length which puts a constraint on the device size in a typical\nnon-equilibrium set-up to observe super Bloch oscillations where the device is\nconnected to the leads. Entanglement entropy provides useful signatures for all\nof these phenomena, and an alternate way to capture the various length scales\ninvolved.",
        "positive": "Effects of Spatial Dispersion on the Casimir Force between Graphene\n  Sheets: The Casimir force between graphene sheets is investigated with emphasis on\nthe effect from spatial dispersion using a combination of factors, such as a\nnonzero chemical potential and an induced energy gap. We distinguish between\ntwo regimes for the interaction - T=0 $K$ and $T\\neq 0$ $K$. It is found that\nthe quantum mechanical interaction (T=0 $K$) retains its distance dependence\nregardless of the inclusion of dispersion. The spatial dispersion from the\nfinite temperature Casimir force is found to contribute for the most part from\n$n=0$ Matsubara term. These effects become important as graphene is tailored to\nbecome a poor conductor by inducing a band gap."
    },
    {
        "anchor": "Long-lived populations of momentum- and spin-indirect excitons in\n  monolayer WSe$_2$: Monolayer transition metal dichalcogenides are a promising platform to\ninvestigate many-body interactions of excitonic complexes. In monolayer\ntungsten diselenide, the ground-state exciton is dark (spin-indirect), and the\nvalley degeneracy allows low-energy dark momentum-indirect excitons to form.\nInteractions between the dark exciton species and the optically accessible\nbright exciton (X) are likely to play significant roles in determining the\noptical properties of X at high power, as well as limiting the ultimate exciton\ndensities that can be achieved, yet so far little is known about these\ninteractions. Here, we demonstrate long-lived dense populations of\nmomentum-indirect intervalley ($X_K$) and spin-indirect intravalley (D) dark\nexcitons by time-resolved photoluminescence measurements (Tr-PL). Our results\nuncover an efficient inter-state conversion between X to D excitons through the\nspin-flip process and the one between D and $X_K$ excitons mediated by the\nexchange interaction (D + D to $X_K$ + $X_K$). Moreover, we observe a\npersistent redshift of the X exciton due to strong excitonic screening by $X_K$\nexciton with a response time in the timescale of sub-ns, revealing a\nnon-trivial inter-state exciton-exciton interaction. Our results provide a new\ninsight into the interaction between bright and dark excitons, and point to a\npossibility to employ dark excitons for investigating exciton condensation and\nthe valleytronics.",
        "positive": "Spin current generation and detection by a double quantum dot structure: We propose a device acting as a spin valve which is based on a double quantum\ndot structure with parallel topology. Using the exact analytical solution for\nthe noninteracting case we argue that, at a certain constellation of system\nparameters and externally applied fields, the electric current through the\nconstriction can become almost fully spin-polarized. We discuss the influence\nof the coupling asymmetry, finite temperatures and interactions on the\nefficiency of the device and make predictions for the experimental realization\nof the effect."
    },
    {
        "anchor": "Topological phase transition in commensurate multi-frequency Floquet\n  Su-Schrieffer-Heeger model: Recently, Floquet systems have attracted a great deal of interest as they\noffer unprecedented ability to engineer topological states through the tuning\nof an external time-periodic drive. Consequentially, seeking new driving\nprotocols that allow for more exotic topological phases and transitions becomes\nimperative for the Floquet engineer. In this paper, we study the\nSu-Schrieffer-Heeger model driven by two time-dependent periodic sources with\ncommensurate frequencies and an amplitude modulation. Imposing more than one\ndriving frequency allows us to realize even more exotic topological phases\nresulting from new couplings appearing in the Fourier space representation.\nMoreover, we find an experimentally practical method for sweeping the system\nthrough a topological phase transition by varying the amplitude mixture of the\ncommensurate sources. We employ the local Chern marker, a real space\nrepresentation of the Chern number, to simulate topological phase diagrams of\nthe two-drive Floquet Hamiltonian in a variety of driving cases.",
        "positive": "Surface-sensitive NMR in optically pumped semiconductors: We present a scheme of surface-sensitive nuclear magnetic resonance in\noptically pumped semiconductors, where an NMR signal from a part of the surface\nof a bulk compound semiconductor is detected apart from the bulk signal. It\nutilizes optically oriented nuclei with a long spin-lattice relaxation time as\na polarization reservoir for the second (target) nuclei to be detected. It\nprovides a basis for the nuclear spin polarizer [IEEE Trans. Appl. Supercond.\n14, 1635 (2004)], which is a polarization reservoir at a surface of the\noptically pumped semiconductor that polarizes nuclear spins in a target\nmaterial in contact through the nanostructured interfaces."
    },
    {
        "anchor": "Band tail formation in mono and multilayered transition metal\n  dichalcogenides: A detailed assessment and a quick-reference guide: Transition metal dichalcogenides (TMDs) are promising candidates for a wide\nvariety of ultrascaled electronic, quantum computation, and optoelectronic\napplications. The exponential decay of electronic density of states into the\nbandgap, i.e. the band tail has a strong impact on the performance of TMD\napplications. In this work, the band tails of various TMD monolayer and\nmultilayer systems when placed on various dielectric substrates is predicted\nwith density functional theory based nonequilibrium Green's functions. Nonlocal\nscattering of electrons on polar optical phonons, charged impurities and remote\nscattering on phonons in the dielectric materials is included in the\nself-consistent Born approximation. The band tails are found to critically\ndepend on the layer thickness, temperature, doping concentration and\nparticularly on the chosen dielectric substrate. The underlying physical\nmechanisms are studied in high detail and an analytical interpolation formula\nis given to provide a quick-reference for Urbach parameters in $MoS_2$, $WS_2$\nand $WSe_2$.",
        "positive": "Spinmotive force with static and uniform magnetization induced by a\n  time-varying electric field: A new spinmotive force is predicted in ferromagnets with spin-orbit coupling.\nBy extending the theory of spinmotive force, we show that a time-varying\nelectric field can induce a spinmotive force with static and uniform\nmagnetization. This spinmotive has two advantages; it can be detected free from\nthe inductive voltage owing to the absence of dynamical magnetization and it\ncan be tuned by electric fields. To observe the effect, we propose two\nexperimental setups: electric voltage measurement in a single ferromagnet and\nspin injection from a ferromagnet into an attached nonmagnetic conductor."
    },
    {
        "anchor": "Sintering-coalescence transition on the nanoscale as a bifurcation\n  phenomenon: molecular dynamics study: Using the isothermal molecular dynamics (MD), coalescence/sintering of Au\nnanoparticles (NPs) was simulated by employing the Nose-Hoover thermostat. The\nMD simulation was realized by using the well-known open program LAMMPS, its\nversion for parallel calculations on GPUs. We have found that the solid NP\nsintering scenario is switched to the coalescence scenario not at the NP\nmelting temperature Tm exactly but at a lower temperature T0=0.9Tm interpreted\nas the critical temperature corresponding to a coalescence/sintering\nbifurcation phenomenon: in the temperature range from T0-2K to T0+2K the\nresulting (daughter) NPs of the same size can have either liquid-like or\ncrystalline structure after coalescence/sintering at the same fixed\ntemperature. The crystallize and liquid states were identify by analyzing the\ndegree of crystallinity and the radial distribution function. For this purpose\nwe employed the OVITO program.",
        "positive": "Graphene with time-dependent spin-orbit coupling: Truncated Magnus\n  expansion approach: We analyze the role of ac-driven Rashba spin-orbit coupling in monolayer\ngraphene including a spin-dependent mass term. Using the Magnus expansion as a\nsemi-analytical approximation scheme a full account of the quasienergie\nspectrum of spin states is given. We discuss the subtleties arising in\ncorrectly applying the Magnus expansion technique in order to determine the\nquasienergy spectrum. Comparison to the exact numerical solution gives\nappropriate boundaries to the validity of the Magnus expansion solution."
    },
    {
        "anchor": "Josephson Effects in a Bose-Einstein Condensate of Magnons: A phenomenological theory is developed, that accounts for the collective\ndynamics of a Bose-Einstein condensate of magnons. In terms of such description\nwe discuss the nature of spontaneous macroscopic interference between magnon\nclouds, highlighting the close relation between such effects and the well known\nJosephson effects. Using those ideas we present a detailed calculation of the\nJosephson oscillations between two magnon clouds, spatially separated in a\nmagnonic Josephson junction.",
        "positive": "Dynamic Oscillations of Magnetization in High Spin Magnetic Clusters: We have studied the time evolution of magnetization of a high spin magnetic\ncluster in the ground state, in the presence of a sinusoidal axial magnetic\nfield and a static transverse field by explicitly solving time dependent\nschr\\\"odinger equation. We observe oscillations of magnetization in the plateau\nregion which has all the characteristics reminiscent of the oscillation of\nprobability of occupation of a state in a two level lattice in the presence of\nan oscillating electric field. The high spin of the ground state leads to a\nlarge but finite two-level pseudo-lattice. The oscillations in magnetization\noccur at amplitude of magnetic fields achievable in a laboratory and they also\npersist for a wide range of spin-dipolar interactions.\n  Thus, our study provides a magnetic analog of the optical two-level lattice."
    },
    {
        "anchor": "Semiconductor-ferromagnet-superconductor planar heterostructures for 1D\n  topological superconductivity: Hybrid structures of semiconducting (SM) nanowires, epitaxially grown\nsuperconductors (SC), and ferromagnetic-insulator (FI) layers have been\nexplored experimentally and theoretically as alternative platforms for\ntopological superconductivity at zero magnetic field. Here, we analyze a\ntripartite SM/FI/SC heterostructure but realized in a planar stacking geometry,\nwhere the thin FI layer acts as a spin-polarized tunneling barrier between the\nSM and the SC. We optimize the system's geometrical parameters using\nmicroscopic simulations, finding the range of FI thicknesses for which the\nhybrid system can be tuned into the topological regime. Within this range, and\nthanks to the vertical confinement provided by the stacking geometry, trivial\nand topological phases alternate regularly as the external gate is varied,\ndisplaying a hard topological gap that can reach half of the SC one. This is a\nsignificant improvement compared to setups using hexagonal nanowires, which\nshow erratic topological regions with typically smaller and softer gaps. Our\nproposal provides a magnetic field-free planar design for quasi-one-dimensional\ntopological superconductivity with attractive properties for experimental\ncontrol and scalability.",
        "positive": "Many body effects in finite metallic carbon nanotubes: The non homogeneity of the charge distribution in a carbon nanotube leads to\nthe formation of an excitonic resonance, in a similar way to the one observed\nin X-ray absorption in metals. As a result, a positive anomaly at low bias\nappears in the tunnelling density of states. This effect depends on the\nscreening of the electron--electron interactions by metallic gates, and it\nmodifies the coupling of the nanotube to normal and superconducting electrodes."
    },
    {
        "anchor": "Observation of Anderson localization in ultrathin films of\n  three-dimensional topological insulators: Anderson localization, the absence of diffusive transport in disordered\nsystems, has been manifested as hopping transport in numerous electronic\nsystems, whereas in recently discovered topological insulators it has not been\ndirectly observed. Here we report experimental demonstration of transition from\ndiffusive transport in the weak antilocalization regime to variable range\nhopping transport in the Anderson localization regime with ultrathin\n(Bi$_{1-x}$Sb$_x$)$_2$Te$_3$ films. As disorder becomes stronger, negative\nmagnetoconductivity due to the weak antilocalization is gradually suppressed,\nand eventually positive magnetoconductivity emerges when the electron system\nbecomes strongly localized. This works reveals the critical role of disorder in\nthe quantum transport properties of ultrathin topological insulator films, in\nwhich theories have predicted rich physics related to topological phase\ntransitions.",
        "positive": "Wavelength Dependence of the Electrical and Optical Readout of NV\n  Centers in Diamond: We study the contrast for electrical and optical readout of NV centers in\ndiamond in dependence of the optical excitation wavelength using different\nexcitation schemes. While the optically detected magnetic resonance (ODMR)\nworks efficiently between 480 and 580 nm, electrically detected magnetic\nresonance (EDMR) shows a strong dependence on the excitation dynamics. The\nhighest, electrically detected contrast of -23% is achieved by resonantly\nexciting the zero-phonon line of the neutral charge state of NV at 575 nm. EDMR\nis also enhanced at 521 nm, possibly due to a further excited state of NV$^-$."
    },
    {
        "anchor": "Exciton states in cylindrical nanowires: The exciton ground state and excited state energies are calculated for a\nmodel system of an infinitely long cylindrical wire. The effective Coulomb\npotential between the electron and the hole is studied as function of the wire\nradius. Within the adiabatic approximation, we obtain `exact' numerical results\nfor the effective exciton potential and the lowest exciton energy levels which\nare fitted to simple analytical expressions. Furthermore, we investigated the\ninfluence of a magnetic field parallel to the nanowire on the effective\npotential and the exciton energy.",
        "positive": "Probing Magnetic Excitations and Correlations in Single and Coupled Spin\n  Systems with Scanning Tunneling Spectroscopy: Spectroscopic measurements with low-temperature scanning tunneling\nmicroscopes have been used very successfully for studying not only individual\natomic or molecular spins on surfaces but also complexly designed coupled\nsystems. The symmetry breaking of the supporting surface induces magnetic\nanisotropy which lead to characteristic fingerprints in the spectrum of the\ndifferential conductance and can be well understood with simple model\nHamiltonians. Furthermore, correlated many-particle states can emerge due to\nthe interaction with itinerant electrons of the electrodes, making these\nsystems ideal prototypical quantum systems. In this manuscript more complex\nbipartite and spin-chains will be discussed additionally. Their spectra enable\nto determine precisely the nature of the interactions between the spins which\ncan lead to the formation of new quantum states which emerge by interatomic\nentanglement."
    },
    {
        "anchor": "Fizeau Drag in Graphene Plasmonics: Dragging of light by moving dielectrics was predicted by Fresnel and verified\nby Fizeau's celebrated experiments with flowing water. This momentous discovery\nis among the experimental cornerstones of Einstein's special relativity and is\nwell understood in the context of relativistic kinematics. In contrast,\nexperiments on dragging photons by an electron flow in solids are riddled with\ninconsistencies and so far eluded agreement with the theory. Here we report on\nthe electron flow dragging surface plasmon polaritons (SPPs): hybrid\nquasiparticles of infrared photons and electrons in graphene. The drag is\nvisualized directly through infrared nano-imaging of propagating plasmonic\nwaves in the presence of a high-density current. The polaritons in graphene\nshorten their wavelength when launched against the drifting carriers. Unlike\nthe Fizeau effect for light, the SPP drag by electrical currents defies the\nsimple kinematics interpretation and is linked to the nonlinear electrodynamics\nof the Dirac electrons in graphene. The observed plasmonic Fizeau drag enables\nbreaking of time-reversal symmetry and reciprocity at infrared frequencies\nwithout resorting to magnetic fields or chiral optical pumping.",
        "positive": "Cooper pair tunneling in junctions of singlet quantum Hall states and\n  superconductors: We propose tunnel junctions of a Hall bar and a superconducting lead, for\nobserving Cooper-pair tunneling into singlet fractional quantum Hall edge\nstates. These tunnel junctions provide a natural means of extracting precise\ninformation of the spin polarization and the filling factor of the state. The\nlow energy regime of one of the set-ups is governed by a novel quantum\nentangled fixed point."
    },
    {
        "anchor": "Valley polarization transition in a two-dimensional electron gas: We theoretically study transport signatures associated with a spontaneous\n2-valley to 1-valley quantum phase transition in a two-dimensional electron gas\n(2DEG) tuned by decreasing the 2D carrier density, as claimed in a recent\nexperiment [Phys. Rev. Lett. 127, 116601 (2021)]. The key issue we focus on is\nwhether the experimentally measured 2D resistivity as a function of carrier\ndensity is consistent (or not) with an underlying spontaneous\nvalley-polarization transition as assumed uncritically in the experimental\nreport. Our theoretical analysis is particularly germane since the experiment\ndoes not directly measure the change in the Fermi surface resulting from the\nvalley polarization transition, but infers such a transition indirectly through\ntransport measurements. We validate the experimental claim, showing that indeed\nthe observed sudden change in the 2D resistivity is quantitatively consistent\nwith a sudden change in the valley polarization from 2 to 1 at the critical\ndensity.",
        "positive": "Ground State Wavefunctions of General Filling Factors in the Lowest\n  Landau Level: We present a set of explicit trial wavefunctions for the filling factors\n\\nu=n/(2n\\pm 1) and \\nu=1/2 in the symmetric gauge. We show that the zeroes of\nthe wavefunction, except those dictated by the Fermi statistics, are detached\nfrom the particles. The evolution of zeroes as the filling factor is varied is\nexamined. We show that the wavefunction at half-filling exhibits a 2k_F-like\noscillation in its occupation number profile. The center-of-mass motion of the\nground state droplet is described in terms of the intra-Landau- level\nexcitations of composite fermions."
    },
    {
        "anchor": "Correlation energy, quantum phase transition, and bias potential effects\n  in quantum Hall bilayers at nu=1: We study the correlation energy, the effective anisotropy parameter, and\nquantum fluctuations of the pseudospin magnetization in bilayer quantum Hall\nsystems at total filling factor nu=1 by means of exact diagonalizations of the\nHamiltonian in the spherical geometry. We compare exact diagonalization results\nfor the ground state energy with finite-size Hartree-Fock values. In the\nordered ground state phase at small layer separations the Hartree-Fock data\ncompare reasonably with the exact results. Above the critical layer separation,\nhowever, the Hartree-Fock findings still predict an increase in the ground\nstate energy, while the exact ground state energy is in this regime independent\nof the layer separation indicating the decoupling of layers and the loss of\nspontaneous phase coherence between them. We also find accurate values for the\npseudospin anisotropy constant whose dependence of the layer separation\nprovides another very clear indication for the strong interlayer correlations\nin the ordered phase and shows an inflection point at the phase boundary.\nFinally we discuss the possibility of interlayer correlations in biased systems\neven above the phase boundary for the balanced case. Certain features of our\ndata for the pseudospin anisotropy constant as well as for quantum fluctuations\nof the pseudospin magnetization are not inconsistent with the occurence of this\neffect. However, it appears to be rather weak at least in the limit of\nvanishing tunneling amplitude.",
        "positive": "Pseudo-Euler equations from nonlinear optics: plasmon-assisted\n  photodetection beyond hydrodynamics: A great deal of theoretical and experimental efforts have been devoted in the\nlast decades to the study of long-wavelength photodetection mechanisms in\nfield-effect transistors hosting two-dimensional (2D) electron systems. A\nparticularly interesting subclass of these mechanisms is intrinsic and based on\nthe conversion of the incoming electromagnetic radiation into plasmons, which\nresonantly enhance the photoresponse, and subsequent rectification via\nhydrodynamic nonlinearities. In this Article we show that such conversion and\nsubsequent rectification occur well beyond the frequency regime in which\nhydrodynamic theory applies. We consider the nonlinear optical response of\ngeneric 2D electron systems and derive pseudo-Euler equations of motion for\nsuitable collective variables. These are solved in one- and two-dimensional\ngeometries for the case of graphene and the results are compared with those of\nhydrodynamic theory. Significant qualitative differences are found, which are\namenable to experimental studies. Our theory expands the knowledge of the\nfundamental physics behind long-wavelength photodetection."
    },
    {
        "anchor": "Direct measurement of interfacial Dzyaloshinskii-Moriya interaction in\n  X/CoFeB/MgO heterostructures with a scanning-NV magnetometer: The Dzyaloshinskii-Moriya Interaction (DMI) has recently attracted\nconsiderable interest owing to its fundamental role in the stabilization of\nchiral spin textures in ultrathin ferromagnets, which are interesting\ncandidates for future spintronic technologies. Here we employ a scanning\nnano-magnetometer based on a single nitrogen-vacancy (NV) defect in diamond to\nlocally probe the strength of the interfacial DMI in CoFeB/MgO ultrathin films\ngrown on different heavy metal underlayers X=Ta,TaN, and W. By measuring the\nstray field emanating from DWs in micron-long wires of such materials, we\nobserve deviations from the Bloch profile for TaN and W underlayers that are\nconsistent with a positive DMI value favoring right-handed chiral spin\nstructures. Moreover, our measurements suggest that the DMI constant might vary\nlocally within a single sample, illustrating the importance of local probes for\nthe study of magnetic order at the nanoscale.",
        "positive": "Stable and scalable metallic phase on MoS2 using forming-gas microwave\n  plasma: Monolithic realization of metallic 1T and semiconducting 2H polymorphic\nphases makes MoS2 a potential candidate for future microelectronic circuits.\nThough co-existence of these phases has been reported, a method for engineering\na stable 1T phase in a scalable manner, compatible with the standard device\nfabrication schemes is yet to emerge. In addition, there are no comprehensive\nstudies on the electrical properties of the 1T phase. In this manuscript, we\ndemonstrate a controllable and scalable 2H to 1T phase engineering technique\nfor MoS2 using Ar + H2 microwave plasma. The technique enables us to realize 1T\nMoS2 starting from the 2H phase of arbitrary thickness and area. Our method\nallows lithographically defining continuous 1T regions in a 2H sample. The 1T\nsamples withstand aging in excess of a few weeks in ambience and show a thermal\nstability up to 300 C, making it suitable for standard device fabrication\ntechniques. We conduct both two-probe and four-probe electrical transport\nmeasurements on devices with back-gated field effect transistor geometry in a\ntemperature range of 4 K to 300 K. The 1T samples exhibit Ohmic current-voltage\ncharacteristics in all temperature ranges without any dependence to the gate\nvoltage, a signature indicative of metallic state. The sheet resistance of our\n1T MoS2 sample is considerably lower than that of 2H samples while the carrier\nconcentration of the 1T sample is few orders of magnitude higher than that of\nthe 2H samples. In addition, our samples show negligible temperature dependence\nof resistance from 4 K to 300 K ruling out any hoping mediated or activated\nelectrical transport."
    },
    {
        "anchor": "Blowing of polysilicon fuses: Polysilicon fuses are one time programmable memory elements which allow the\ncalibration of integrated circuits at wafer and package level. We present a\nzero dimensional lumped parameter model of the programming of fuses made from a\ncombination of tungsten silicide and polycrystalline silicon. The components of\nthe model are an electrical model, a thermal model and a flow model. The\nelectrical model describes the temperature and geometry dependent resistance of\nthe fuse. The thermal model describes the heating and melting of the fuse and\nits surroundings. The flow model describes the disconnection of the fuse by\nelectromigration driven flow of silica. The model generates quantitatively\naccurate results and reproduces trends with applied voltage and fuse size.",
        "positive": "Effect of the inter-subband spin-orbit interaction on the spin\n  transistor operation: We consider the electron transport in the Datta-Das spin transistor within\nthe two-subband model taking into account the intra- and inter-subband\nspin-orbit (SO) interaction and study the influence of the inter-subband SO\ncoupling on the spin-transistor operation. Starting from the model, in which\nthe SO coupling constants are treated as parameters, we show that the\ninter-subband SO interaction strongly affects the ordinary conductance\noscillations predicted for the transistor with the single occupancy.\nInterestingly, we find that even in the absence of the intra-subband SO\ninteraction, the conductance oscillates as a function of the inter-subband SO\ncoupling constant. This phenomenon is explained as resulting from the\ninter-subband transition with spin-flip. Next, we consider the realistic spin\ntransistor model based on the gated\nAl$_{0.48}$In$_{0.52}$As/Ga$_{0.47}$In$_{0.53}$As double quantum well, for\nwhich the SO coupling constants are determined by the Schr\\\"{o}dinger-Poisson\napproach. We show that the SO coupling constants rapidly change around $V_g=0$,\nwhich is desirable for the spin transistor operation. We demonstrate that for\nhigh electron densities the inter-subband SO interaction starts to play the\ndominant role. The strong evidence of this interaction is the reduction of the\nconductance for gate voltage $V_g=0$, which leads to the reduction of the\non/off conductance ratio."
    },
    {
        "anchor": "Theoretical Study of Fano Resonance in Single-Walled Carbon Nanotubes: Electrical transport through single-walled carbon nanotubes (SWNTs) is\ninvestigated by using the nearest-neighbor tight-binding model coupled with two\nelectron reservoirs. When the SWNT-electrode coupling is not axially symmetric,\nasymmetric resonance peaks are found in the conductance and are considered to\nbe due to the interference between two transport channels. These Fano\nresonances are sensitive to the coupling with electrodes. When the coupling is\naxially symmetric, no asymmetric resonance peaks are observed.",
        "positive": "Magnetic Kronig-Penney model for Dirac electrons in single-layer\n  graphene: The properties of Dirac electrons in a magnetic superlattice (SL) on graphene\nconsisting of very high and thin (delta-function) barriers are investigated. We\nobtain the energy spectrum analytically and study the transmission through a\nfinite number of barriers. The results are contrasted with those for electrons\ndescribed by the Schrodinger equation. In addition, a collimation of an\nincident beam of electrons is obtained along the direction perpendicular to\nthat of the SL. We also highlight the analogy with optical media in which the\nrefractive index varies in space."
    },
    {
        "anchor": "Interface control of the magnetic chirality in CoFeB|MgO\n  heterosctructures with heavy metal underlayers: Recent advances in the understanding of spin orbital effects in ultrathin\nmagnetic heterostructures have opened new paradigms to control magnetic moments\nelectrically. The Dzyaloshinskii-Moriya interaction (DMI) is said to play a key\nrole in forming a Neel-type domain wall that can be driven by the spin Hall\ntorque, a torque resulting from the spin current generated in a neighboring\nnon-magnetic layer via the spin Hall effect. Here we show that the strength and\nsign of the DMI can be changed by modifying the adjacent heavy metal underlayer\n(X) in perpendicularly magnetized X|CoFeB|MgO heterstructures. Albeit the same\nspin Hall angle, a domain wall moves along or against the electron flow\ndepending on the underlayer. We find that the sense of rotation of a domain\nwall spiral11 is reversed when the underlayer is changed from Hf to W and the\nstrength of DMI varies as the number of 5d electrons of the heavy metal layer\nchanges. The DMI can even be tuned by adding nitrogen to the underlayer, thus\nallowing interface engineering of the magnetic texture in ultrathin magnetic\nheterostructures.",
        "positive": "Topological Hall Effect in Magnetic Topological Insulator Films: Geometric Berry phase can be induced either by spin-orbit coupling, giving\nrise to the anomalous Hall effect in ferromagnetic materials, or by chiral spin\ntexture, such as skyrmions, leading to the topological Hall effect. Recent\nexperiments have revealed that both phenomena can occur in topological\ninsulator films with magnetic doping, thus providing us with an intriguing\nplatform to study the interplay between these two phenomena. In this work, we\nnumerically study the anomalous Hall and topological Hall effects in a\nfour-band model that can properly describe the quantum well states in the\nmagnetic topological insulator films by combining Landauer-Buttiker formula and\nthe iterative Green's function method. Our numerical results suggest that\nspin-orbit coupling in this model plays a different role in the quantum\ntransport in the clean and disordered limits. In the clean limit, spin-orbit\ncoupling mainly influences the longitudinal transport but does not have much\neffect on topological Hall conductance. Such behavior is further studied\nthrough the analytical calculation of scattering cross-section due to skyrmion\nwithin the four-band model. In the disordered limit, the longitudinal transport\nis determined by disorder scattering and spin-orbit coupling is found to affect\nstrongly the topological Hall conductance. This sharp contrast unveils a\ndramatic interplay between spin-orbit coupling and disorder effect in\ntopological Hall effect in magnetic topological insulator systems."
    },
    {
        "anchor": "Ultrastrong magnon-photon coupling and entanglement in\n  superconductor/ferromagnet nanostructures: Ultrastrong light-matter coupling opens exciting possibilities to generate\nsqueezed quantum states and entanglement. Here we propose a way to achieve this\nregime in superconducting hybrid nanostructures with ferromagnetic interlayers.\nStrong confinement of electromagnetic field between superconducting plates is\nfound to result in the existence of magnon-polariton modes with ultrastrong\nmagnon-photon coupling, ultra-high cooperativity and very large group\nvelocities. These modes provide a numerically accurate explanation of recent\nexperiments and have intriguing quantum properties. The magnon-polariton\nquantum vacuum consists of the squeezed magnon and photon states with the\ndegree of squeezing controlled in wide limits by the external magnetic field.\nThe ground state population of virtual photons and magnons is shown to be very\nlarge which can be used for generating correlated magnon and photon pairs.\nExcited states of magnon-polaritons contain bipartite entanglement between\nmagnons and photons. This property can be used for transferring entanglement\nbetween different types of quantum systems.",
        "positive": "A microstructural analysis of 2D halide perovskites: Stability and\n  functionality: Recent observations indicated that the photoelectric conversion properties of\nperovskite materials are intimately related to the presence of superlattice\nstructures and other unusual nanoscale features in them. The low dimensional or\nmixed dimensional halide perovskite family are found to be more efficient\nmaterials for device application compared to 3-dimensional halide perovskites.\nThe emergence of perovskite solar cell has revolutionized the solar cell\nindustry because of their flexible architecture and rapidly increased\nefficiency. Tuning the dielectric constant, charge separation are the main\nobjective in designing a photovoltaic device that can be explored using\n2-dimensional perovskite family. Thus, revisiting the fundamental properties of\nperovskite crystals could reveal further possibilities for recognizing these\nimprovements towards device functionality. In this context, this review\ndiscusses the material properties of 2-dimensional halide perovskite and\nrelated optoelectronic devices aiming particularly for solar cell application."
    },
    {
        "anchor": "Complex-band-structure eigenvalue method adapted to Floquet systems:\n  topological superconducting wires as a case study: For systems that can be modeled as a single-particle lattice extended along a\nprivileged direction as, e.g., quantum wires, the so-called eigenvalue method\nprovides full information about the propagating and evanescent modes as a\nfunction of energy. This complex-band structure method can be applied either to\nlattices consisting of an infinite succession of interconnected layers\ndescribed by the same local Hamiltonian or to superlattices: Systems in which\nthe spatial periodicity involves more than one layer. Here, for time-dependent\nsystems subject to a periodic driving, we present an adapted version of the\nsuperlattice scheme capable of obtaining the Floquet states and the Floquet\nquasienergy spectrum. Within this scheme the time periodicity is treated as\nexisting along spatial dimension added to the original system. The solutions at\na single energy for the enlarged artificial system provide the solutions of the\noriginal Floquet problem. The method is suited for arbitrary periodic\nexcitations including strong and anharmonic drivings. We illustrate the\ncapabilities of the methods for both time-independent and time-dependent\nsystems by discussing: (a) topological superconductors in multimode quantum\nwires with spin-orbit interaction and (b) microwave driven quantum dot in\ncontact with a topological superconductor.",
        "positive": "Magnetic properties of Dy nano-islands on graphene: We have determined the magnetic properties of epitaxially grown Dy islands on\ngraphene/SiC(0001) that are passivated by a gold film (deposited in the\nultra-high vacuum growth chamber) for {\\it ex-situ} X-ray magnetic circular\ndichroism (XMCD). Our sum-rule analysis of the Dy $M_{4,5}$ XMCD spectra at low\ntemperatures ($T=15$ K) as a function of magnetic field assuming Dy$^{3+}$\n(spin configuration $^6H_{15/2}$) indicate that the projection of the magnetic\nmoment along an applied magnetic field of 5 T is 3.5(3) $\\mu_B$. Temperature\ndependence of the magnetic moment (extracted from the $M_5$ XMCD spectra) shows\nan onset of a change in magnetic moment at about 175 K in proximity of the\ntransition from paramagnetic to helical magnetic structure at $T_{\\rm H} =179$\nK in bulk Dy. No feature at the vicinity of the ferromagnetic transition of hcp\nbulk Dy at $T_{\\rm c}$ = 88 K is observed. However, below $\\sim$130 K, the\ninverse magnetic moment (extracted from the XMCD) is linear in temperature as\ncommonly expected from a paramagnetic system suggesting different behavior of\nDy nano-island than bulk Dy."
    },
    {
        "anchor": "Haldane Quantum Hall Effect for Light in a Dynamically Modulated Array\n  of Resonators: Topological insulators have attracted abundant attention for a variety of\nreasons -- notably, the possibility for lossless energy transport through edge\nstates `protected' against disorder. Topological effects like the Quantum Hall\nstate can be induced through a gauge field, which is however hard to create in\npractice, especially for charge-neutral particles. One way to induce an\neffective gauge potential is through a dynamic, time-periodic modulation of the\nlattice confining such particles. In this way, the Haldane Quantum Hall effect\nwas recently observed in a cold atom system. Here, we show how this same effect\ncan be induced for light confined to a lattice of identical optical resonators,\nusing an on-site modulation of the resonant frequencies. We further demonstrate\nthe existence of one-directional edge states immune to back-scattering losses,\nand discuss the possibilities for a practical implementation, which would\nenable slow-light devices of unprecedented quality.",
        "positive": "Two-dimensional electron gas in a periodic potential and external\n  magnetic field: states of pairs and three-particle systems: The group-theoretical classification of states of identical particle pairs is\npresented. Then obtained states are coupled with those of an antiparticle to\nconstruct states of a three-particle system. Investigations are performed using\nproducts of irreducible projective representations of the 2D translation group.\nFor a given BvK period N degeneracy of pair states is N, whereas three-particle\nstates are N^2-fold degenerated. It has to be underlined that the case of even\nN is more complicated since pair states are labelled by four inequivalent\nirreducible projective representations. The problem of symmetry properties with\nrespect to particles transposition is briefly discussed."
    },
    {
        "anchor": "Shear shuffling governs plastic flow in nanocrystalline metals: An\n  analysis of thermal activation parameters: From strain rate- and temperature-dependent deformation studies on\nnanocrystalline PdAu alloys with grain sizes $\\leq$ 10nm, the shear activation\nvolume $6b^3$, strain rate sensitivity 0.03 as well as the Helmholtz 0.9eV and\nGibbs free energy of activation 0.2eV have been extracted. The close similarity\nto values found for metallic glasses indicates that grain boundary mediated\nshear shuffling dominates plasticity at the low end of the nanoscale. More\nfundamentally, we find that the energy barrier height exhibits universal\nscaling behavior $\\Delta G \\propto \\Delta\\tau^{3/2}$, where $\\Delta\\tau$ is a\nresidual load, giving rise to a generalization of the Johnson-Samwer $T^{2/3}$\nscaling law of yielding in metallic glasses.",
        "positive": "Anomalous Temperature Dependence of Quantum Correction to the\n  Conductivity of Magnetic Topological Insulators: Quantum transport in magnetic topological insulators reveals the strong\ninterplay between the magnetism and topology of electronic band structures. A\nrecent experiment on magnetically doped topological insulator Bi2Se3 thin films\nshowed the anomalous temperature dependence of the magnetoconductivity while\ntheir field dependence presents a clear signature of weak anti-localization\n[Tkac et al., Phys. Rev. Lett. 123, 036406(2019)]. Here we demonstrate that the\ntiny mass of the surface electrons induced by the bulk magnetization leads to a\ntemperature-dependent correction to the \\pi Berry phase, and generates a\ndecoherence mechanism to the phase coherence length of the surface electrons.\nAs a consequence, the quantum correction to the conductivity can exhibit\nnon-monotonic behavior by decreasing the temperature. This effect is attributed\nto the close relation of the Berry phase and quantum interference of the\ntopological surface electrons in quantum topological materials."
    },
    {
        "anchor": "The Effect of Non-Local Electrical Conductivity on Near-Field Radiative\n  Heat Transfer between Graphene Sheets: Graphene's near-field radiative heat transfer is determined from its\nelectrical conductivity, commonly modeled using the local Kubo and Drude\nformulas. In this letter, we analyze the non-locality of graphene's electrical\nconductivity using the Lindhard model combined with the Mermin relaxation time\napproximation. We also study how the variation of electrical conductivity with\nwavevector affects near-field radiative conductance between two graphene sheets\nseparated by a vacuum gap. It is shown that the variation of electrical\nconductivity with wavevector, $k_{\\rho}$, is appreciable for $k_{\\rho}$s\ngreater than $100k_0$, where $k_0$ is the magnitude of the wavevector in the\nfree space. The Kubo electrical conductivity provides an accurate estimation of\nthe spectral radiative conductance between two graphene sheets except for\naround the surface-plasmon-polariton frequency of graphene and at separation\ngaps smaller than 20 nm where there is a non-negligible contribution from modes\nwith $k_{\\rho}>100k_0$ to the radiative conductance. The Drude formula proves\nto be inaccurate for modeling the electrical conductivity and radiative\nconductance of graphene except for at temperatures much below the Fermi\ntemperature and frequencies much smaller than $2{\\mu}_c/{\\hbar}$, where\n${\\mu}_c$ and ${\\hbar}$ are the chemical potential and reduced Planck's\nconstant, respectively. It is also shown that the electronic scattering\nprocesses should be considered in the Lindhard model properly, such that the\nlocal electron number is conserved. A substitution of ${\\omega}$ by\n${\\omega}+i{\\gamma}$ (${\\omega}$, $i$, and ${\\gamma}$ being the angular\nfrequency, imaginary unit, and scattering rate, respectively) in the\ncollisionless Lindhard model does not satisfy the conservation of the local\nelectron number and results in significant errors in computing graphene's\nelectrical conductivity and radiative conductance.",
        "positive": "Dualities in fractional statistics: We first reobtain in a simpler way the Haldane fractional statistics at\nthermal equilibrium using an interpolation argument. We then show that the mean\noccupation number for fractional statistics is invariant to a group of duality\ntransformations, a nonabelian subgroup of the fractional linear group"
    },
    {
        "anchor": "Polaron-induced changes in moir\u00e9 exciton propagation in twisted van\n  der Waals heterostructures: Twisted transition metal dichalcogenides (TMDs) present an intriguing\nplatform for exploring excitons and their transport properties. By introducing\na twist angle, a moir\\'e superlattice forms, providing a spatially dependent\nexciton energy landscape. Based on a microscopic many-particle theory, we\ninvestigate in this work polaron-induced changes in exciton transport\nproperties in the MoSe$_2$/WSe$_2$ heterostructure. We demonstrate that polaron\nformation and the associated enhancement of moir\\'e excitonic mass lead to a\nsignificant band flattening. As a result, the hopping rate and the propagation\nvelocity undergo noticeable temperature and twist-angle dependent changes. We\npredict a reduction of the hopping strength ranging from 80% at a twist angle\nof 1$^\\circ$ to 30% at 3$^\\circ$ at room temperature. The provided microscopic\ninsights into the spatio-temporal exciton dynamics in presence of a moir\\'e\npotential further deepens our understanding of the intriguing moir\\'e exciton\nphysics.",
        "positive": "Casimir Effect for Massless Fermions in One Dimension: A Force Operator\n  Approach: We calculate the Casimir interaction between two short range scatterers\nembedded in a background of one dimensional massless Dirac fermions using a\nforce operator approach. We obtain the force between two finite width square\nbarriers, and take the limit of zero width and infinite potential strength to\nstudy the Casimir force mediated by the fermions. For the case of identical\nscatterers we recover the conventional attractive one dimensional Casimir\nforce. For the general problem with inequivalent scatterers we find that the\nmagnitude and sign of this force depend on the relative spinor polarizations of\nthe two scattering potentials which can be tuned to give an attractive, a\nrepulsive, or a compensated null Casimir interaction."
    },
    {
        "anchor": "Localization phenomena in a DNA double helix structure : A twisted\n  ladder model: In this work we propose a model for DNA double helix within the tight-binding\nframework that incorporates the helicity of the molecules. We have studied\nlocalization properties of three DNAsequences,the periodic poly(dG)-poly(dC)\nand poly(dA)-poly(dT) sequences and the random ATGCsequence, all of which are\ncoupled to backbone withrandom site energies representing the\nenvironmentalfluctuations. We observe that due to helicity of DNA, electron\ntransport is greatly enhancedand there exists almost a disorder-strength\nindependent critical value of the hopping integral, thataccounts for helicity\nof DNA, for which the electronic states become maximally extended. We havealso\ninvestigated the effect of backbone energetics on the transmission and I-V\ncharacteristics of DNA.",
        "positive": "Floquet higher-order topological insulators and superconductors with\n  space-time symmetries: Floquet higher-order topological insulators and superconductors (HOTI/SCs)\nwith an order-two space-time symmetry or antisymmetry are classified. This is\nachieved by considering unitary loops, whose nontrivial topology leads to the\nanomalous Floquet topological phases, subject to a space-time\nsymmetry/antisymmetry. By mapping these unitary loops to static Hamiltonians\nwith an order-two crystalline symmetry/antisymmetry, one is able to obtain the\n$K$ groups for the unitary loops and thus complete the classification of\nFloquet HOTI/SCs. Interestingly, we found that for every order-two nontrivial\nspace-time symmetry/antisymmetry involving a half-period time translation,\nthere exists a unique order-two static crystalline symmetry/antisymmetry, such\nthat the two symmetries/antisymmetries give rise to the same topological\nclassification. Moreover, by exploiting the frequency-domain formulation of the\nFloquet problem, a general recipe that constructs model Hamiltonians for\nFloquet HOTI/SCs is provided, which can be used to understand the\nclassification of Floquet HOTI/SCs from an intuitive and complimentary\nperspective."
    },
    {
        "anchor": "Fast barrier-free switching in synthetic antiferromagnets: We analytically solve the Landau-Lifshitz equations for the collective\nmagnetization dynamics in a synthetic antiferromagnet (SAF) nanoparticle and\nuncover a regime of barrier-free switching under a short small-amplitude\nmagnetic field pulse applied perpendicular to the SAF plane. We give examples\nof specific implementations for forming such low-power and ultra-fast switching\npulses. For fully optical, resonant, barrier-free SAF switching we estimate the\npower per write operation to be $ \\sim 100 $ pJ, 10-100 times smaller than for\nconventional quasi-static rotation, which should be attractive for memory\napplications.",
        "positive": "Tunneling anisotropic magnetoresistance in single-molecule magnet\n  junctions: We theoretically investigate quantum transport through single-molecule magnet\n(SMM) junctions with ferromagnetic and normal-metal leads in the sequential\nregime. The current obtained by means of the rate-equation gives rise to the\ntunneling anisotropic magnetoresistance (TAMR), which varies with the angle\nbetween the magnetization direction of ferromagnetic lead and the easy axis of\nSMM. The angular dependence of TAMR can serve as a probe to determine\nexperimentally the easy axis of SMM. Moreover, it is demonstrated that both the\nmagnitude and sign of TAMR are tunable by the bias voltage, suggesting a\npromising TAMR based spintronic molecule-device."
    },
    {
        "anchor": "Dynamics of parametric fluctuations induced by quasiparticle tunneling\n  in superconducting flux qubits: We present experiments on the dynamics of a two-state parametric fluctuator\nin a superconducting flux qubit. In spectroscopic measurements, the fluctuator\nmanifests itself as a doublet line. When the qubit is excited in resonance with\none of the two doublet lines, the correlation of readout results exhibits an\nexponential time decay which provides a measure of the fluctuator transition\nrate. The rate increases with temperature in the interval 40 to 158 mK. Based\non the magnitude of the transition rate and the doublet line splitting we\nconclude that the fluctuation is induced by quasiparticle tunneling. These\nresults demonstrate the importance of considering quasiparticles as a source of\ndecoherence in flux qubits.",
        "positive": "Entropy measurement of a strongly coupled quantum dot: The spin 1/2 entropy of electrons trapped in a quantum dot has previously\nbeen measured with great accuracy, but the protocol used for that measurement\nis valid only within a restrictive set of conditions. Here, we demonstrate a\nnovel entropy measurement protocol that is universal for arbitrary mesoscopic\ncircuits and apply this new approach to measure the entropy of a quantum dot\nhybridized with a reservoir, where Kondo correlations dominate spin physics.\nThe experimental results match closely to numerical renormalization group (NRG)\ncalculations for small and intermediate coupling. For the largest couplings\ninvestigated in this work, NRG predicts a suppression of spin entropy at the\ncharge transition due to the formation of a Kondo singlet, but that suppression\nis not observed in the experiment."
    },
    {
        "anchor": "Nondiagonal Graphene Conductivity in the Presence of In-Plane Magnetic\n  Fields: We study the electron/hole transport in puddle-disordered and rough graphene\nsamples which are subject to in-plane magnetic fields. Previous treatments,\nmostly devoted to regimes where the electron/hole scattering wavelengths are\nlarger than the surface height correlation length, are based on the use of\ntransport equations with appropriate forms for the collision term. We point out\nin this work, as a counterpoint, that classical Lorentz force effects, which\nare expected to hold when the Fermi level is far enough away from the charge\nneutral point, can be heuristically assessed through disordered Boltzmann\nequations that contain magnetic-field dependent material derivatives, and keep\nthe zero magnetic-field structure of the collision term. It turns out that the\nelectric conductivity tensor gets a peculiar nondiagonal component, induced by\nthe in-plane magnetic field that crosses the rough topography of the graphene\nsheet, even if the projected random transverse magnetic field vanishes in the\nmean. Numerical estimates of the transverse conductivities suggest that they\nare suitable of observation under conditions which are within the reach of\nup-to-date experimental methods.",
        "positive": "Dirac semimetal thin films in in-plane magnetic fields: In this work we study the effects of in-plane magnetic fields on thin films\nof the Dirac Semimetal (DSM) \\ce{Na2Bi} where one of the in-plane directions is\nperpendicular to the $k$-separation between the two Weyl points for each spin\norientation. We show numerically that the states localized near the surface of\nthese thin films are related to the Fermi arc states in semi-infinite slabs.\nDue to the anisotropy between the two in-plane directions, the application of a\nmagnetic field along these directions have differing effects. A field parallel\nto the $k$ space separation between the Weyl points leads to a broadening of\nthe surface state band and a formation of an energy plateau, while a\nperpendicular field shifts the energy where the hole and particle bands meet\nupwards and sharpens the tips of the bands. We illustrate the effects of these\nchanges to the bandstructure by studying the transmission from a source segment\nwithout a magnetic field to a drain segment with a field with the field and\ninterface at various in-plane directions."
    },
    {
        "anchor": "Spin interactions and switching in vertically tunnel-coupled quantum\n  dots: We determine the spin exchange coupling J between two electrons located in\ntwo vertically tunnel-coupled quantum dots, and its variation when magnetic (B)\nand electric (E) fields (both in-plane and perpendicular) are applied. We\npredict a strong decrease of J as the in-plane B field is increased, mainly due\nto orbital compression. Combined with the Zeeman splitting, this leads to a\nsinglet-triplet crossing, which can be observed as a pronounced jump in the\nmagnetization at in-plane fields of a few Tesla, and perpendicular fields of\nthe order of 10 Tesla for typical self-assembled dots. We use harmonic\npotentials to model the confining of electrons, and calculate the exchange J\nusing the Heitler-London and Hund-Mulliken technique, including the long-range\nCoulomb interaction. With our results we provide experimental criteria for the\ndistinction of singlet and triplet states and therefore for microscopic spin\nmeasurements. In the case where dots of different sizes are coupled, we present\na simple method to switch on and off the spin coupling with exponential\nsensitivity using an in-plane electric field. Switching the spin coupling is\nessential for quantum computation using electronic spins as qubits.",
        "positive": "Longitudinal Seebeck coefficient of the charge ordered layered crystals\n  in a strong quantizing magnetic field: The longitudinal Seebeck coefficient of the charge-ordered layered crystals\nin a strong quantizing magnetic field normal to layers plane has been\ndetermined. The conditions whereby charge ordering parameter and chemical\npotential are oscillating functions of magnetic field induction are considered.\nThe longitudinal Seebeck coefficient has been calculated for two models of\nrelaxation time:i)constant relaxation time and ii)relaxation time proportional\nto the longitudinal velocity. It has been shown that in a quasi-classical\nregion of magnetic fields for the case of relaxation time proportional to the\nlongitudinal velocity Seebeck coefficient is less than for the case of constant\nrelaxation time. In this region for selected problem parameters it does not\nexceed 4.37mu\\V/K.In the strong quantizing magnetic fields for both models of\nthe relaxation time the longitudinal Seebeck coefficient is virtually the same.\nFor selected problem parameters its maximal modulus is 2033\\muV/K. At the same\ntime, in the disordered layered crystals,in a quasi-classical region,the\nSeebeck coefficient is approximately one order of magnitude less than for the\ncharge ordered crystals. In the strong magnetic fields,the Seebeck coefficient\nfor the disordered layered crystals is factor of 7 or 9 less than for the\ncharge ordered crystals. However,in super strong magnetic fields,under current\ncarriers concentration in the only filled Landau sub-band,for both models of of\nthe relaxation time the modulus of the Seebeck coefficient tends to zero\naccording to asymptotic law \\alpha_{zz}\\proptoB^{-2}."
    },
    {
        "anchor": "Efficiency of Mesoscopic Detectors: We consider a mesoscopic measuring device whose conductance is sensitive to\nthe state of a two-level system. The detector is described with the help of its\nscattering matrix. Its elements can be used to calculate the relaxation and\ndecoherence time of the system, and determine the characteristic time for a\nreliable measurement. We derive conditions needed for an efficient ratio of\ndecoherence and measurement time. To illustrate the theory we discuss the\ndistribution function of the efficiency of an ensemble of open chaotic\ncavities.",
        "positive": "Chromodynamics of photons in an artificial non-Abelian magnetic\n  Yang-Mills field: Artificial gauge fields, simulating real phenomenologies that unfold in a\nvast variety of systems, offer extraordinary possibilities to study extreme\nphysical effects in many different environments, from high energy physics to\nquantum mechanics and cosmology. They are also at the heart of topological\nphysics. Here, exploiting a strongly anisotropic material under strong coupling\nregime, we experimentally synthesize a Yang-Mills non-Abelian gauge field\nacting on an exciton-polariton quantum flow like a magnetic field. We observe\nexperimentally the corresponding curved trajectories and spin precession. This\nmotion follows chromodynamics equations which normally describe the quarks\nstrong interactions and their color. Our work therefore opens exciting\nperspectives of simulating quark-gluon dynamics using highly flexible photonic\nsimulators. It makes of sub-atomic physics a potential new playground to apply\ntopological physics concepts."
    },
    {
        "anchor": "Experimental Observation of the Spectral Gap in Microwave n-Disk Systems: Symmetry reduced three-disk and five-disk systems are studied in a microwave\nsetup. Using harmonic inversion the distribution of the imaginary parts of the\nresonances is determined. With increasing opening of the systems, a spectral\ngap is observed for thick as well as for thin repellers and for the latter case\nit is compared with the known topological pressure bounds. The maxima of the\ndistributions are found to coincide for a large range of the distance to radius\nparameter with half of the classical escape rate. This confirms theoretical\npredictions based on rigorous mathematical analysis for the spectral gap and on\nnumerical experiments for the maxima of the distributions.",
        "positive": "Transitions between Volume-Localized Electron Quantum Levels of\n  Fullerene C60 Ion: The excited short-lived volume-localized electron quantum levels (VLELs)\nexistent due to Coulomb potential well inside positive ion are analytically\ninvestigated in the paper using a simplified spherical fullerene model. Hence,\nthose electron levels appear exclusively after the ionization of neutral\nfullerene taking into account the unique geometrical shape of sphere. The\nexistence of those levels is argued, and their basic parameters (the energy\nlevels, the wave eigenfunctions) are approximately calculated. The wave\nfunctions of VLELs are basically localized inside fullerene ion sphere (with a\nmaximum amplitude in the centre) in contrast to ordinary surface-localized\nelectron levels (SLELs) having a wave functions in the vicinity of fullerene\nsphere formed by the cluster composed of carbon ions. Contrary to VLELs, the\nwave functions of SLELs are present both in charged and neutral fullerene. The\nanalysis of electron beam interaction with the medium consistent of fullerenes\nions is conducted as the application of the methods developed. The analytical\ndependencies of free electron recombination cross-sections for the capture to\nthe volume-localized electron levels are obtained. It is shown that the\nprobabilities of electron capture to these VLELs are considerably larger\ncompared to capture to SLELs. Also, the calculational results of dipole moments\nfor quantum transitions from fullerene ions VLELs to other VLELs and to SLELs\nwith spontaneous photon emission are also presented in the paper. The\ncalculated dipole moments depend on fullerene ionization extent, initial and\nfinal electron states, and are varied from about 0.2 to 5 in atomic system of\nunits. Finally, the principal possibility of coherent radiation generation on\nfullerene ions VLELs is discussed."
    },
    {
        "anchor": "Robust implementation of quantum gates despite always-on exchange\n  coupling in silicon double quantum dots: Addressability of spin qubits in a silicon double quantum dot setup in the\n(1,1) charge configuration relies on having a large difference between the\nZeeman splittings of the electrons. When the difference is not sufficiently\nlarge, the rotating wave approximation becomes inaccurate. We consider a device\nworking in this regime, with always-on exchange coupling, and describe how a CZ\ngate and arbitrary one-qubit gates which are robust against charge noise can be\nimplemented by smoothly pulsing the microwave source, while eliminating the\ncrosstalk. We find that the most significant deviations from the rotating wave\napproximation, which are analogous to the Bloch-Siegert shift in a two-level\nsystem, can be compensated using local virtual gates.",
        "positive": "Hypergeometric resummation of self-consistent sunset diagrams for\n  electron-boson quantum many-body systems out of equilibrium: A newly developed hypergeometric resummation technique [H. Mera et al., Phys.\nRev. Lett. 115, 143001 (2015)] provides an easy-to-use recipe to obtain\nconserving approximations within the self-consistent nonequilibrium many-body\nperturbation theory. We demonstrate the usefulness of this technique by\ncalculating the phonon-limited electronic current in a model of a\nsingle-molecule junction within the self-consistent Born approximation for the\nelectron-phonon interacting system, where the perturbation expansion for the\nnonequilibrium Green function in powers of the free bosonic propagator\ntypically consists of a series of non-crossing \\sunset\" diagrams.\nHypergeometric resummation preserves conservation laws and it is shown to\nprovide substantial convergence acceleration relative to more standard\napproaches to self-consistency. This result strongly suggests that the\nconvergence of the self-consistent \\sunset\" series is limited by a branch-cut\nsingularity, which is accurately described by Gauss hypergeometric functions.\nOur results showcase an alternative approach to conservation laws and\nself-consistency where expectation values obtained from conserving perturbation\nexpansions are \\summed\" to their self-consistent value by analytic continuation\nfunctions able to mimic the convergence-limiting singularity structure."
    },
    {
        "anchor": "The violation of the Hund's rule in semiconductor artificial atoms: The unrestricted Pople-Nesbet approach for real atoms is adapted to quantum\ndots, the man-made artificial atoms, under applied magnetic field. Gaussian\nbasis sets are used instead of the exact single-particle orbitals in the\nconstruction of the appropriated Slater determinants. Both system chemical\npotential and charging energy are calculated, as also the expected values for\ntotal and z-component in spin states. We have verified the validity of the\nenergy shell structure as well as the Hund's rule state population at zero\nmagnetic field. Above given fields, we have observed a violation of the Hund's\nrule by the suppression of triplets and quartets states at the 1p energy shell,\ntaken as an example. We also compare our present results with those obtained\nusing the LS-coupling scheme for low electronic occupations. We have focused\nour attention to ground-state properties for GaAs quantum dots populated up to\nforty electrons.",
        "positive": "Mechanical and Thermal Stability of Graphyne and Graphdiyne Nanoscrolls: Graphynes and graphdiynes are carbon 2D allotrope structures presenting both\nsp2 and sp hybridized atoms. These materials have been theoretically predicted\nbut due to intrinsic difficulties in their synthesis, only recently some of\nthese structures have been experimentally realized. Graphyne nanoscrolls are\nstructures obtained by rolling up graphyne sheets into papyrus-like structures.\nIn this work we have investigated, through fully atomistic reactive molecular\ndynamics simulations, the dynamics of nanoscroll formation for a series of\ngraphyne ({\\alpha}, \\b{eta}, and {\\delta} types) structures. We have also\ninvestigated their thermal stability for a temperature range of 200-1000K. Our\nresults show that stable nanoscrolls can be formed for all structures\nconsidered here. Their stability depends on a critical value of the ratio\nbetween width and height of the graphyne sheets. Our findings also show that\nthese structures are structurally less stable then graphene-based nanoscrolls.\nThis can be explained by the graphyne higher structural porosity which results\nin a decreased pi-pi stacking interactions"
    },
    {
        "anchor": "Large anomalous magnetic moment in three-dimensional Dirac and Weyl\n  semimetals: We investigate the effect of Coulomb interactions on the electromagnetic\nresponse of three-dimensional Dirac and Weyl semimetals. In a calculation\nreminiscent of Schwinger's seminal work on quantum electrodynamics, we find\nthree physically distinct effects for the anomalous magnetic moment of the\nrelativisticlike quasiparticles in the semimetal. In the case of nonzero\ndoping, the anomalous magnetic moment is finite at long wavelengths and\ntypically orders of magnitude larger than Schwinger's result. We also find\ninteresting effects of one of the three new Hamiltonian terms on the\ntopological surface states at the interface between vacuum and a Weyl\nsemimetal. We conclude that observation of these effects should be within\nexperimental reach.",
        "positive": "Phase rigidity breaking in open Aharonov-Bohm ring coupled to a\n  cantilever: The conductance and the transmittance phase shifts of a two-terminal\nAharonov-Bohm (AB) ring are analyzed in the presence of mechanical\ndisplacements due to coupling to an external can- tilever. We show that phase\nrigidity is broken, even in the linear response regime, by means of inelastic\nscattering due to phonons. Our device provides a way of observing continuous\nvariation of the transmission phase through a two-terminal\nnano-electro-mechanical system (NEMS). We also propose measurements of phase\nshifts as a way to determine the strength of the electron-phonon coupling in\nNEMS."
    },
    {
        "anchor": "Estimation of the electrical and thermal contact resistances and\n  thermoemf of thermoelectric material-metal transient contact layer due to\n  semiconductor surface rougness: The impact of semiconductor surface roughness on the electrical and thermal\ncontact resistances and thermoEMF of thermoelectric material (TEM)-metal\ntransient contact layer is studied theoretically. The distribution of hollows\nand humps on the rough surface is simulated by the truncated Gaussian\ndistribution. The impact of distribution parameters on the electrical contact\nresistance and thermoEMF of thermoelectric material-metal contact is studied.",
        "positive": "Electrical control of inter-dot electron tunneling in a quantum dot\n  molecule: We employ ultrafast pump-probe spectroscopy to directly monitor electron\ntunneling between discrete orbital states in a pair of spatially separated\nquantum dots. Immediately after excitation, several peaks are observed in the\npump-probe spectrum due to Coulomb interactions between the photo-generated\ncharge carriers. By tuning the relative energy of the orbital states in the two\ndots and monitoring the temporal evolution of the pump-probe spectra the\nelectron and hole tunneling times are separately measured and resonant\ntunneling between the two dots is shown to be mediated both by elastic and\ninelastic processes. Ultrafast (< 5 ps) inter-dot tunneling is shown to occur\nover a surprisingly wide bandwidth, up to ~8 meV, reflecting the spectrum of\nexciton-acoustic phonon coupling in the system."
    },
    {
        "anchor": "Work Extraction and Landauer's Principle in a Quantum Spin Hall Device: Landauer's principle states that erasure of each bit of information in a\nsystem requires at least a unit of energy $k_B T \\ln 2$ to be dissipated. In\nreturn, the blank bit may possibly be utilized to extract usable work of the\namount $k_B T \\ln 2$, in keeping with the second law of thermodynamics. While\nin principle any collection of spins can be utilized as information storage,\nwork extraction by utilizing this resource in principle requires specialized\nengines that are capable of using this resource. In this work, we focus on heat\nand charge transport in a quantum spin Hall device in the presence of a spin\nbath. We show how a properly initialized nuclear spin subsystem can be used as\na memory resource for a Maxwell's Demon to harvest available heat energy from\nthe reservoirs to induce charge current that can power an external electrical\nload. We also show how to initialize the nuclear spin subsystem using applied\nbias currents which necessarily dissipate energy, hence demonstrating\nLandauer's principle. This provides an alternative method of \"energy storage\"\nin an all-electrical device. We finally propose a realistic setup to\nexperimentally observe a Landauer erasure/work extraction cycle.",
        "positive": "Universality and quantized response in bosonic nonfractionalized\n  tunneling: We show that tunneling involving bosonic wires and/or boson integer quantum\nHall (bIQH) edges is characterized by universal features which are absent in\ntheir fermionic counterparts. Considering a pair of minimal geometries, we find\na low energy enhancement and a universal high versus zero energy relation for\nthe tunnel conductance that holds for all wire/bIQH edge combinations. Features\ndistinguishing bIQH edges include a current imbalance to chemical potential\nbias ratio that is quantized despite the lack of conductance quantization in\nthe bIQH edges themselves. The predicted phenomena require only initial states\nto be thermal and thus are well suited for tests with ultracold bosons forming\nwires and bIQH states. For the latter, we highlight a potential realization\nbased on single component bosons in the recently observed Harper-Hofstadter\nbandstructure."
    },
    {
        "anchor": "Crystallization of fractional charges in a strongly interacting\n  quasi-helical quantum dot: The ground-state electron density of a one-dimensional spin-orbit coupled\nquantum dot with a Zeeman term and strong electron interaction is studied at\nthe fractional helical liquid points. We show that at fractional filling\nfactors $\\nu=(2n+1)^{-1}$ (with $n$ a non-negative integer) the density\noscillates with $N_{0}/\\nu$ peak. For $n\\geq 1$ a number of peaks larger than\nthe number of electrons $N_{0}$ suggests that a crystal of fractional\nquasi-particles with charge $\\nu e$ (with $e$ the electron charge) occurs. The\nreported effect is amenable of verification via transport measurements in\ncharged AFM-coupled dot.",
        "positive": "Theory of polariton-electron interactions in semiconductor microcavities: We develop a microscopic description of an electron-doped two-dimensional\nsemiconductor embedded in a microcavity. Specifically, we investigate the\ninteractions between exciton-polaritons and electrons for the case where the\ninteractions between charges are strongly screened and the system is spin\npolarized. As a starting point, we obtain an analytic expression for the\nexciton-polariton wave function, and we relate the microscopic parameters of\nthe light-matter system to experimentally measurable quantities, such as the\nRabi coupling and the cavity photon frequency. We then derive the\npolariton-electron interaction within the standard Born approximation and\ncompare it with the exact polariton-electron scattering $T$ matrix that we\nobtain from a diagrammatic approach that has proven highly successful in the\ncontext of nuclear physics and ultracold atomic gases. In particular, we show\nthat the Born approximation provides an upper bound on the polariton-electron\ncoupling strength at vanishing momentum. Using our exact microscopic\ncalculation, we demonstrate that polariton-electron scattering can be strongly\nenhanced compared to the exciton-electron case, which is the opposite of that\nexpected from the Born approximation. We furthermore expose a resonance-like\npeak at scattering momenta near the polariton inflection point, whose size is\nset by the strength of the light-matter coupling. Our results arise from the\nnon-Galilean nature of the polariton system and should thus be applicable to a\nrange of semiconductor microcavities such as GaAs quantum wells and atomically\nthin materials."
    },
    {
        "anchor": "Quantization of non-Abelian Berry phase for time reversal invariant\n  systems: We present a quantized non-Abelian Berry phase for time reversal invariant\nsystems such as quantum spin Hall effect. Ordinary Berry phase is defined by an\nintegral of Berry's gauge potential along a loop (an integral of the\nChern-Simons one-form), whereas we propose that a similar integral but over\nfive dimensional parameter space (an integral of the Chern-Simons five-form) is\nsuitable to define a non-Abelian Berry phase. We study its global topological\naspects and show that it is indeed quantized into two values. We also discuss\nits close relationship with the nonperturbative anomalies.",
        "positive": "Persistent current in metals with a large dephasing rate: In a weakly disordered metal electron interactions are responsible for both\ndecoherence of the quasi-particles as well as for quantum corrections to\nthermodynamic properties. We consider electrons which are interacting with\ntwo-level-systems. We show that the two-level-systems enhance the average\nequilibrium (``persistent'') current in an ensemble of mesoscopic rings. The\nresult supports the recent suggestion that two puzzles in mesoscopic physics\nmay be related: The low temperature saturation of the dephasing time and the\nhigh persistent current in rings."
    },
    {
        "anchor": "Breakdown of Fast Water Transport in Graphene Oxides: Fast slip flow was reported for water inside the interlayer gallery between\ngraphene layers or carbon nanotubes. We report here that this flow rate\nenhancement (over two orders) breaks down with the presence of chemical\nfunctionalization and relaxation of the nanoconfinement in graphene oxides.\nMolecular dynamics simulation results show that hydrodynamics applies in this\ncircumstance, even at length scales down to nanometers. However, corrections on\nthe slip boundary condition and viscosity of nanoconfined flow must be included\nto make quantitative predictions. These results were discussed with structural\ncharacteristics of the liquid water and hydrogen bond networks.",
        "positive": "Skyrmion dynamics in a chiral magnet driven by periodically varying spin\n  currents: In this work, we investigated the spin dynamics in a slab of chiral magnets\ninduced by an alternating (ac) spin current. Periodic trajectories of the\nskyrmion in real space are discovered under the ac current as a result of the\nMagnus and viscous forces, which originate from the Gilbert damping, the spin\ntransfer torque, and the $ \\beta $-nonadiabatic torque effects. The results are\nobtained by numerically solving the Landau-Lifshitz-Gilbert equation and can be\nexplained by the Thiele equation characterizing the skyrmion core motion."
    },
    {
        "anchor": "Nonlinear motion and mechanical mixing in as-grown GaAs nanowires: We report nonlinear behavior in the motion of driven nanowire cantilevers.\nThe nonlinearity can be described by the Duffing equation and is used to\ndemonstrate mechanical mixing of two distinct excitation frequencies.\nFurthermore, we demonstrate that the nonlinearity can be used to amplify a\nsignal at a frequency close to the mechanical resonance of the nanowire\noscillator. Up to 26 dB of amplitude gain are demonstrated in this way.",
        "positive": "Exchange rules for diradical \u03c0-conjugated hydrocarbons: A variety of planar {\\pi}-conjugated hydrocarbons such as heptauthrene,\nClar's goblet and, recently synthesized, triangulene have two electrons\noccupying two degenerate molecular orbitals. The resulting spin of the\ninteracting ground state is often correctly anticipated as S = 1, extending the\napplication of Hund's rules to these systems, but this is not correct in some\ninstances. Here we provide a set of rules to correctly predict the existence of\nzero mode states, as well as the spin multiplicity of both the ground state and\nthe low-lying excited states, together with their open- or closed-shell nature.\nThis is accomplished using a combination of analytical arguments and\nconfiguration interaction calculations with a Hubbard model, both backed by\nquantum chemistry methods with a larger Gaussian basis set. Our results go\nbeyond the well established Lieb's theorem and Ovchinnikov's rule, as we\naddress the multiplicity and the open-/closed-shell nature of both ground and\nexcited states."
    },
    {
        "anchor": "Spin-dependent transport in a driven noncolinear antiferromagnetic\n  fractal network: Noncolinear magnetic texture breaks the spin-sublattice symmetry which gives\nrise to a spin-splitting effect. Inspired by this, we study the spin-dependent\ntransport properties in a noncolinear antiferromagnetic fractal structure,\nnamely, the Sierpinski Gasket (SPG) triangle. We find that though the spin-up\nand spin-down currents are different, the degree of spin polarization is too\nweak. Finally, we come up with a proposal, where the degree of spin\npolarization can be enhanced significantly in the presence of a time-periodic\ndriving field. Such a prescription of getting spin-filtering effect from an\nunpolarized source in a fractal network is completely new to the best of our\nknowledge. Starting from a higher generation of SPG to smaller ones, the\nprecise dependencies of driving field parameters, spin-dependent scattering\nstrength, interface sensitivity on spin polarization are critically\ninvestigated. The spatial distribution of spin-resolved bond current density is\nalso explored. Interestingly, our proposed setup exhibits finite spin\npolarization for different spin-quantization axes. Arbitrarily polarized light\nis considered and its effect is incorporated through Floquet-Bloch ansatz. All\nthe spin-resolved transport quantities are computed using Green's function\nformalism following the Landauer-B\\\"{u}ttiker prescription. The present work\nbrings forth new insights into spintronic properties of noncolinear\nantiferromagnetic SPG and should entice the AFM spintronic community to explore\nother fractal structures with the possibility of unconventional features.",
        "positive": "Spin relaxation in $n$-type ZnO quantum wells: We perform an investigation on the spin relaxation for $n$-type ZnO (0001)\nquantum wells by numerically solving the kinetic spin Bloch equations with all\nthe relevant scattering explicitly included. We show the temperature and\nelectron density dependence of the spin relaxation time under various\nconditions such as impurity density, well width, and external electric field.\nWe find a peak in the temperature dependence of the spin relaxation time at low\nimpurity density. This peak can survive even at 100 K, much higher than the\nprediction and measurement value in GaAs. There also exhibits a peak in the\nelectron density dependence at low temperature. These two peaks originate from\nthe nonmonotonic temperature and electron density dependence of the Coulomb\nscattering. The spin relaxation time can reach the order of nanosecond at low\ntemperature and high impurity density."
    },
    {
        "anchor": "Magnetotransport in disordered two-dimensional topological insulators:\n  signatures of charge puddles: In this numerical study we investigate the influence and interplay of\ndisorder, spin-orbit coupling and magnetic field on the edge-transport in\nHgTe/CdTe quantum wells in the framework of coherent elastic scattering. We\nshow that the edge states remain unaffected by the combined effect of moderate\ndisorder and a weak magnetic field at realistic spin-orbit coupling strengths.\nAgreement with the experimentally observed linear magnetic field dependence for\nthe conductance of long samples is obtained when considering the existence of\ncharge puddles.",
        "positive": "Graphene adhesion on mica: Role of surface morphology: We investigate theoretically the adhesion and electronic properties of\ngraphene on a muscovite mica surface using the density functional theory (DFT)\nwith van der Waals (vdW) interactions taken into account (the vdW-DF approach).\nWe found that irregularities in the local structure of cleaved mica surface\nprovide different mechanisms for the mica-graphene binding. By assuming\nelectroneutrality for both surfaces, the binding is mainly of vdW nature,\nbarely exceeding thermal energy per carbon atom at room temperature. In\ncontrast, if potassium atoms are non uniformly distributed on mica, the\ndifferent regions of the surface give rise to $n$- or $p$-type doping of\ngraphene. In turn, an additional interaction arises between the surfaces,\nsignificantly increasing the adhesion. For each case the electronic states of\ngraphene remain unaltered by the adhesion. It is expected, however, that the\nFermi level of graphene supported on realistic mica could be shifted relative\nto the Dirac point due to asymmetry in the charge doping. Obtained variations\nof the distance between graphene and mica for different regions of the surface\nare found to be consistent with recent atomic force microscopy experiments. A\nrelative flatness of mica and the absence of interlayer covalent bonding in the\nmica-graphene system make this pair a promising candidate for practical use."
    },
    {
        "anchor": "Edge theory of the non-Hermitian skin modes in higher dimensions: In this Letter, we establish an effective edge theory to characterize\nnon-Hermitian edge-skin modes in higher dimensions. We begin by proposing a\nbulk projection criterion to straightforwardly identify the localized edges of\nskin modes. Through an exact mapping, we show that the edge-skin mode shares\nthe same bulk-boundary correspondence and localization characteristics as the\nzero-energy edge states in a Hermitian semimetal under open-boundary\nconditions, bridging the gap between non-Hermitian edge-skin effect and\nHermitian semimetals. Another key finding is the introduction of skewness, a\nterm we proposed to describe the characteristic decay direction of skin mode\nfrom the localized edge into the bulk. Remarkably, we demonstrate that skewness\nis an intrinsic quantity of the skin mode and can be analytically determined\nusing the non-Bloch bulk Hamiltonian with real-valued momenta along the\nlocalized edge, without requiring any boundary details. Furthermore, we reveal\nthat in the edge-skin effect, the spectrum exhibits anomalous spectral\nsensitivity to weak local disturbances, a feature that crucially distinguishes\nit from the corner-skin effect.",
        "positive": "Origami-controlled strain engineering of tunable flat bands and\n  correlated states in folded graphene: Flat electronic bands with tunable structures offer opportunities for the\nexploitation and manipulation of exotic interacting quantum states. Here, we\npresent a controllable route to construct easily tunable flat bands in folded\ngraphene, by nano origami-controlled strain engineering, and discover\ncorrelated states in this system. Via tearing and folding graphene monolayer at\narbitrary step edges with scanning tunneling microscope manipulation, we create\nstrain-induced pseudo-magnetic fields as well as resulting flat electronic\nbands in the curved edges of folded graphene. We show that the intensity of the\npseudo-magnetic field can be readily tuned by changing the width of the folding\nedge due to the edge-width-dependent lattice deformation, leading to the well\nadjustability of the geometry of flat bands in folded graphene. Furthermore, by\ncreating expected dispersionless flat bands using this technique, the\ncorrelation-induced splits of flat bands are successfully observed in the\ndensity of states when these bands are partially filled. Our experiment\nprovides a feasible and effective pathway to engineer the system with tunable\nflat band structures, and establishes a new platform that can be used to\nrealize devisable strain and interaction induced quantum phases."
    },
    {
        "anchor": "Direct current in a stirred optical lattice: We study how the energy dispersion of bosonic atoms loaded into an optical\nlattice becomes modified due to periodic circular stirring of the lattice to\nthe second order in the strength of stirring. If the lattice breaks mirror\nsymmetry, the bosonic atoms may acquire a nonzero group velocity at the center\nof the Brillouin zone and produce a nonzero direct current. This effect is\nsimilar to the circular photogalvanic effect in solid-state physics. It can be\nused to transport neutral bosonic atoms in an optical lattice over a given\ndistance in an arbitrary direction. However, when the drive frequency is\ndetuned to avoid resonant transitions with energy absorption, we argue that the\ninduced current is not persistent, but transient. An experimental study of the\ninduced current relaxation could give answers to perplexing questions about\nequilibrization in driven systems.",
        "positive": "A topological current divider: We study the transport properties of a hybrid junction made of a\nferromagnetic lead in electrical connection with the helical edge modes of a\ntwo-dimensional topological insulator. In this system, the time reversal\nsymmetry, which characterizes the ballistic edge modes of the topological\ninsulator, is explicitly broken inside the ferromagnetic region. This conflict\nsituation generates unusual transport phenomena at the interface which are the\nmanifestation of the interplay between the spin polarization of the injected\ncurrent and the spin-momentum locking mechanism operating inside the\ntopological insulator. We show that the spin polarized current originated in\nthe ferromagnetic region is asymmetrically divided in spatially separated\nbranch currents sustained by edge channels with different helicity inside the\ntopological insulator. The above findings provide the working principle of a\ntopological current divider in which the relative intensity of the branch\ncurrents is determined by the polarization of the incoming current. We discuss\nthe relevance of this effect in spintronics where, for instance, it offers an\nalternative way to measure the current polarization generated by a\nferromagnetic electrode."
    },
    {
        "anchor": "Optimizing Dirac fermions quasi-confinement by potential smoothness\n  engineering: With the advent of high mobility encapsulated graphene devices, new\nelectronic components ruled by Dirac fermions optics have been envisioned and\nrealized. The main building blocks of electron-optics devices are gate-defined\np-n junctions, which guide, transmit and refract graphene charge carriers, just\nlike prisms and lenses in optics. The reflection and transmission are governed\nby the p-n junction smoothness, a parameter difficult to tune in conventional\ndevices. Here we create p-n junctions in graphene, using the polarized tip of a\nscanning gate microscope, yielding Fabry-P\\'erot interference fringes in the\ndevice resistance. We control the p-n junctions smoothness using the\ntip-to-graphene distance, and show increased interference contrast using\nsmoother potential barriers. Extensive tight-binding simulation reveal that\nsmooth potential barriers induce a pronounced quasi-confinement of Dirac\nfermions below the tip, yielding enhanced interference contrast. On the\nopposite, sharp barriers are excellent Dirac fermions transmitters and lead to\npoorly contrasted interferences. Our work emphasizes the importance of junction\nsmoothness for relativistic electron optics devices engineering.",
        "positive": "Interaction effects and superconductivity signatures in twisted\n  double-bilayer WSe$_2$: Twisted bilayer graphene provides a new two-dimensional platform for studying\nelectron interaction phenomena and flat band properties such as correlated\ninsulator transition, superconductivity and ferromagnetism at certain magic\nangles. Here, we present strong evidence of correlated insulator states and\nsuperconductivity signatures in p-type twisted double-bilayer WSe$_2$. Enhanced\ninterlayer interactions are observed when the twist angle decreases to a few\ndegrees as reflected by the high-order satellites in the electron diffraction\npatterns taken from the 2H/3R-stacked domains reconstructed from a conventional\nMoir\\'e superlattice. In contrast to twisted bilayer graphene, there is no\nspecific magic angle for twisted WSe$_2$. The flat band properties are observed\nat twist angles ranging from 1 to 4 degrees. The highest superconducting\ntransition temperature observed by transport measurement is 6 K. Our work has\nfacilitated future study in the area of flat band related properties in twisted\ntransition metal dichalcogenide layered structures."
    },
    {
        "anchor": "Geometry induced quantum Hall effect and Hall viscosity: For a particle confined to the two-dimensional helical surface embedded in\nfour-dimensional (4D) Euclidean space, the effective Hamiltonian is deduced in\nthe thin-layer quantization formalism. We find that the gauge structure of the\neffective dynamics is determined by torsion, which plays the role of U(1) gauge\npotential, and find that the topological structure of associated states is\ndefined by orbital spin which originates from 4D space. Strikingly, the\nresponse to torsion contributes a quantum Hall effect, and the response to the\ndeformation of torsion contributes Hall viscosity that is perfectly presented\nas a simultaneous occurrence of multiple channels for the quantum Hall effect.\nThis result directly provides a way to probe Hall viscosity.",
        "positive": "Electron states, phonon-assisted relaxation and tunneling in\n  self-assembled quantum dot molecules in an electric field: We present a theoretical analysis of the phonon-assisted relaxation in a\nsystem composed of two self-assembled vertically stacked quantum dots. We\nconstruct realistic model, which takes into account the geometry and strain\ndistribution in the system. We calculate phonon-assisted relaxation rates\nbetween the two lowest states (in one- and two-electron cases). The relaxation\nrates and energy levels are studied as a function of external (axial) electric\nfield and geometry of the structure (dot sizes). We show that the relaxation\ntimes can be as low as 1~ps but efficent relaxation occurs only for very finely\ntuned dots."
    },
    {
        "anchor": "Modeling Transient Negative Capacitance in Steep-Slope FeFETs: We report on measurements and modeling of FE HfZrO/SiO2\nFerroelectric-Dielectric (FE-DE) FETs which indicate that many of the phenomena\nattributed to Negative Capacitance can be explained by a delayed response of\nferroelectric domain switching - referred to as Transient Negative Capacitance\n(TNC). No traversal of the stabilized negative capacitance branch is required.\nModeling is used to correlate the hysteretic properties of the ferroelectric\nmaterial to the measured transient and subthreshold slope (SS) behavior. It is\nfound that steep SS can be understood as a transient phenomenon, present when\nsignificant polarization changes occur. The experimental signature of TNC is\ninvestigated, and guidelines for detecting it in measured data are outlined.\nThe technological implications of FE polarization switching are investigated,\nand it is found that NCFETs relying on it are not suitable for high performance\nCMOS logic, due to voltage, frequency, and hysteresis limitations. Requirements\nfor experimental evidence of stabilized S-curve behavior are summarized.",
        "positive": "Quantum Computation with Quantum Dots: We propose a new implementation of a universal set of one- and two-qubit\ngates for quantum computation using the spin states of coupled single-electron\nquantum dots. Desired operations are effected by the gating of the tunneling\nbarrier between neighboring dots. Several measures of the gate quality are\ncomputed within a newly derived spin master equation incorporating decoherence\ncaused by a prototypical magnetic environment. Dot-array experiments which\nwould provide an initial demonstration of the desired non-equilibrium spin\ndynamics are proposed."
    },
    {
        "anchor": "Tunable nonlinear damping in parametric regime: Nonlinear damping plays a significant role in several area of physics and it\nis becoming increasingly important to understand its underlying mechanism.\nHowever, microscopic origin of nonlinear damping is still a debatable topic.\nHere, we probe and report nonlinear damping in a highly tunable MoS2 nano\nmechanical drum resonator using electrical homodyne actuation and detection\ntechnique. In our experiment, we achieve 2:1 internal resonance by tuning\nresonance frequency and observe enhanced non-linear damping. We probe the\neffect of non-linear damping by characterizing parametric gain. Geometry and\ntunability of the device allow us to reduce the effect of other prominent\nDuffing non-linearity to probe the non-linear damping effectively. The enhanced\nnon-linear damping in the vicinity of internal resonance is also observed in\ndirect drive, supporting possible origin of non-linear damping. Our experiment\ndemonstrates, a highly tunable 2D material based nanoresonator offers an\nexcellent platform to study the nonlinear physics and exploit nonlinear damping\nin parametric regime.",
        "positive": "Spin and Valley Control of Free Carriers in Single-Layer WS$_2$: The semiconducting single-layer transition metal dichalcogenides have been\nidentified as ideal materials for accessing and manipulating spin- and\nvalley-quantum numbers due to a set of favorable optical selection rules in\nthese materials. Here, we apply time- and angle-resolved photoemission\nspectroscopy to directly probe optically excited free carriers in the\nelectronic band structure of a high quality single layer of WS$_2$. We observe\nthat the optically generated free hole density in a single valley can be\nincreased by a factor of 2 using a circularly polarized optical excitation.\nMoreover, we find that by varying the photon energy of the excitation we can\ntune the free carrier density in a given spin-split state around the valence\nband maximum of the material. The control of the photon energy and polarization\nof the excitation thus permits us to selectively excite free electron-hole\npairs with a given spin and within a single valley."
    },
    {
        "anchor": "Conduction of surface electrons in a topological insulator with\n  spatially random magnetization: Using the Green functions method we study transport properties of surface\nelectrons in topological insulators in the presence of a correlated random\nexchange field. Such an exchange field may be due to random magnetization with\ncorrelated fluctuations. We determine the relaxation time due to scattering\nfrom the magnetization fluctuations and from other structural defects. Then we\ncalculate the longitudinal charge conductivity taking into account the\ncontribution due to vertex correction.",
        "positive": "Quantum adiabatic pumping by modulating tunnel phase in quantum dots: In a mesoscopic system, under zero bias voltage, a finite charge is\ntransferred by quantum adiabatic pumping by adiabatically and periodically\nchanging two or more control parameters. We obtained expressions for the pumped\ncharge for a ring of three quantum dots (QDs) by choosing the magnetic flux\npenetrating the ring as one of the control parameters. We found that the pumped\ncharge shows a steplike behavior with respect to the variance of the flux. The\nvalue of the step heights is not universal but depends on the trajectory of the\ncontrol parameters. We discuss the physical origin of this behavior on the\nbasis of the Fano resonant condition of the ring."
    },
    {
        "anchor": "Imaging Electron Wave Functions Inside Open Quantum Rings: Combining Scanning Gate Microscopy (SGM) experiments and simulations, we\ndemonstrate low temperature imaging of electron probability density\n$|\\Psi|^{2}(x,y)$ in embedded mesoscopic quantum rings (QRs). The tip-induced\nconductance modulations share the same temperature dependence as the\nAharonov-Bohm effect, indicating that they originate from electron wavefunction\ninterferences. Simulations of both $|\\Psi|^{2}(x,y)$ and SGM conductance maps\nreproduce the main experimental observations and link fringes in SGM images to\n$|\\Psi|^{2}(x,y)$.",
        "positive": "Homogeneity of Bilayer Graphene: We present non-linear transport measurements on suspended, current annealed\nbilayer graphene devices. Using a multi-terminal geometry we demonstrate that\ndevices tend to be inhomogeneous and host two different electronic phases next\nto each other. Both of these phases show gap-like features of different\nmagnitude in non-linear transport at low charge carrier densities, as already\nobserved in previous studies. Here, we investigate the magnetic field\ndependence and find that both features grow with increasing field, the smaller\none with 0.6 meV/T, the larger one with a 5-10 times higher field dependence.\nWe attribute the larger of the two gaps to an interaction induced broken\nsymmetry state and the smaller one to localization in the more disordered parts\nof the device."
    },
    {
        "anchor": "Tunable plasmon-enhanced birefringence in ribbon array of anisotropic 2D\n  materials: We explore the far-field scattering properties of anisotropic 2D materials in\nribbon array configuration. Our study reveals the plasmon-enhanced linear\nbirefringence in these ultrathin metasurfaces, where linearly polarized\nincident light can be scattered into its orthogonal polarization or be\nconverted into circular polarized light. We found wide modulation in both\namplitude and phase of the scattered light via tuning the operating frequency\nor material's anisotropy and develop models to explain the observed scattering\nbehavior.",
        "positive": "Persistent current in a thin superconducting wire: In this paper, we explore the persistent current in thin superconducting\nwires and accurately examine the effects of the phase slips on that current.\nThe main result of the paper is the formula for persistent current in terms of\nthe solutions of certain (nonlinear) integral equation. This equation allows to\nfind asymptotics of the current at long(small) length of the wire, in that\npaper, we interested in the region in which the system becomes strongly\ninteracting and very few amounts of information can be extracted by\nperturbation theory. Nevertheless, due to the integrability, exact results for\nthe current can be obtained. We observe that at the limit of a long wire, the\ncurrent becomes exponentially small, we believe that it is the signal that\nphase slips may destroy superconductivity for long wires, below BKT phase\ntransition."
    },
    {
        "anchor": "Light--absorbed orbital angular momentum in the linear response regime: In exploring the light-induced dynamics within the linear response regime,\nthis study investigates the induced orbital angular momentum on a wide variety\nof electronic structures. We derive a general expression for the torque induced\nby light on different electronic systems based on their characteristic\ndielectric tensor. We demonstrate that this phenomenon diverges from the\ninverse Faraday effect as it produces an orbital magnetization persistent\npost-illumination. Indeed, our results reveal that, while isotropic\nnon-dissipative materials do not absorb orbital angular momentum from\ncircularly polarized light, any symmetry-breaking arrangement of matter, be it\nspatial or temporal, introduces novel channels for the absorption of orbital\nangular momentum, or magnetization. Most notably, in dissipative materials,\ncircularly polarized light imparts a torque corresponding to a change in\norbital angular momentum of $\\hbar$ per absorbed photon. The potential of these\nmechanisms to drive helicity-dependent magnetic phenomena paves the way for a\ndeeper understanding of light-matter interactions. Notably, the application of\npump-probe techniques in tandem with our findings allows experimentalists to\nquantitatively assess the amount of orbital angular momentum transferred to\nelectrons in matter, thus hopefully enhancing our ability to steer ultrafast\nlight-induced magnetization dynamics.",
        "positive": "Impact of g-factors and valleys on spin qubits in a silicon double\n  quantum dot: We define single electron spin qubits in a silicon MOS double quantum dot\nsystem. By mapping the qubit resonance frequency as a function of gate-induced\nelectric field, the spectrum reveals an anticrossing that is consistent with an\ninter-valley spin-orbit coupling. We fit the data from which we extract an\ninter-valley coupling strength of 43 MHz. In addition, we observe a narrow\nresonance near the primary qubit resonance when we operate the device in the\n(1,1) charge configuration. The experimental data is consistent with a\nsimulation involving two weakly exchanged-coupled spins with a g-factor\ndifference of 1 MHz, of the same order as the Rabi frequency. We conclude that\nthe narrow resonance is the result of driven transitions between the T- and T+\ntriplet states, using an ESR signal of frequency located halfway between the\nresonance frequencies of the two individual spins. The findings presented here\noffer an alternative method of implementing two-qubit gates, of relevance to\nthe operation of larger scale spin qubit systems."
    },
    {
        "anchor": "Voltage-Controlled Low-Energy Switching of Nanomagnets through\n  Ruderman-Kittel-Kasuya-Yosida Interactions for Magnetoelectric Device\n  Applications: In this letter, we consider through simulation Ruderman-Kittel-Kasuya-Yosida\n(RKKY) interactions between nanomagnets sitting on a conductive surface, and\nvoltage-controlled gating thereof for low-energy switching of nanomagnets for\npossible memory and nonvolatile logic applications. For specificity, we\nconsider nanomagnets with perpendicular anisotropy on a three-dimensional\ntopological insulator. We model the possibility and dynamics of RKKY-based\nswitching of one nanomagnet by coupling to one or more nanomagnets of set\norientation. Applications for both memory and nonvolatile logic are considered,\nwith follower, inverter and majority gate functionality shown. Sub-attojoule\nswitching energies, far below conventional spin transfer torque (STT)-based\nmemories and even below CMOS logic appear possible. Switching times on the\norder of a few nanoseconds, comparable to times for STT switching, are\nestimated for ferromagnetic nanomagnets.",
        "positive": "Mapping Charge Recombination and the Effect of Point Defect Insertion in\n  Gallium Arsenide Nanowire Heterojunctions: Electronic devices are extremely sensitive to defects in their constituent\nsemiconductors, but locating electronic point defects in bulk semiconductors\nhas previously been impossible. Here we apply scanning transmission electron\nmicroscopy (STEM) electron beam-induced current (EBIC) imaging to map\nelectronic defects in a GaAs nanowire Schottky diode. Imaging with a\nnon-damaging 80 or 200 kV STEM acceleration potential reveals a\nminority-carrier diffusion length that decreases near the surface of the\nhexagonal nanowire, thereby demonstrating that the device's charge collection\nefficiency (CCE) is limited by surface defects. Imaging with a 300 keV STEM\nbeam introduces vacancy-interstitial (VI, or Frenkel) defects in the GaAs that\nincrease carrier recombination and reduce the CCE of the diode. We create,\nlocate, and characterize a single insertion event, determining that a defect\ninserted 7 nm from the Schottky interface broadly reduces the CCE by 10% across\nthe entire nanowire device. Variable-energy STEM EBIC imaging thus allows both\nbenign mapping and pinpoint modification of a device's e-h recombination\nlandscape, enabling controlled experiments that illuminate the impact of both\nextended (1D and 2D) and point (0D) defects on semiconductor device\nperformance."
    },
    {
        "anchor": "B\u00fcttiker probes and the Recursive Green's Function; an efficient\n  approach to include dissipation in general configurations: An efficient and compact approach to the inclusion of dissipative effects in\nNon-Equilibrium Green's Function (NEGF) simulations of electronic systems is\nintroduced. The algorithm is based on two well known methods in the literature,\nfirstly that of the so-called Recursive Green's Function (RGF) and secondly\nthat of B\\\"uttiker probes. Numerical methods for exact evaluation of the\nJacobian are presented by a direct extension to RGF which can be modularly\nincluded in any codebase that uses it presently. Then using both physical\nobservations and numerical methods, the computation time of the B\\\"uttiker\nprobe Jacobian is improved significantly. An improvement to existing phonon\nmodels within B\\\"uttiker probes is then demonstrated in the simulation of fully\natomistic graphene nanoribbon based field effect transistors in n-i-n and p-i-n\noperation.",
        "positive": "Floquet-Bloch Theory for Nonperturbative Response to a Static Drive: We develop the Floquet-Bloch theory of noninteracting fermions on a periodic\nlattice in the presence of a constant electric field. As long as the field lies\nalong a reciprocal lattice vector, time periodicity of the Bloch Hamiltonian is\ninherited from the evolution of momentum in the Brillouin zone. The\ncorresponding Floquet quasienergies yield the Wannier-Stark ladder with\ninterband couplings included to all orders. These results are compared to\nperturbative results where the lowest-order interband correction gives the\nfield-induced polarization shift in terms of the electric susceptibility.\nAdditionally, we investigate electronic transport by coupling the system to a\nbath within the Floquet-Keldysh formalism. We then study the breakdown of the\nband-projected theory from the onset of interband contributions and Zener\nresonances in the band-resolved currents. In particular, we consider the\ntransverse quantum-geometric response in two spatial dimensions due to the\nBerry curvature. In the strong-field regime, the semiclassical theory predicts\na plateau of the geometric response as a function of field strength. Here, we\nscrutinize the conditions under which the semiclassical results continue to\nhold in the quantum theory."
    },
    {
        "anchor": "Zak phase and band inversion in dimerized one-dimensional locally\n  resonant metamaterials: Zak phase, which refers to the Berry's phase picked up by a particle moving\nacross the Brillouin zone, characterizes the topological properties of Bloch\nbands in one-dimensional periodic system. Here the Zak phase in dimerized\none-dimensional locally resonant metamaterials is investigated. It is found\nthat there are some singular points in the bulk band across which the Bloch\nstates contribute {\\pi} to the Zak phase, whereas while in the rest of the band\nthe contribution is nearly zero. These singular points associated with zero\nreflection are caused by two different mechanisms: the dimerization-independent\nanti-resonating of each branch, and the dimerization-dependent destructive\ninterference in multiple backscattering. The structure undergoes a topological\ntransition point in the band structure where the band inverts and the Zak\nphase, which is determined by the numbers of singular points in the bulk band,\nchanges following a shift in dimerization parameter. Finally, the interface\nstate between two dimerized metamaterial structures with different topological\nproperty in the first band gap is demonstrated experimentally. The\nquasi-one-dimensional configuration of the system allows one to explore\ntopology-inspired new methods and applications in the sub-wavelength scale.",
        "positive": "Addition energies in semiconductor quantum dots: Role of\n  electron-electron interaction: We show that the addition spectra of semiconductor quantum dots in the\npresence of magnetic field can be studied through a theoretical scheme that\nallows an accurate and practical treatment of the single particle states and\nelectron-electron interaction up to large numbers of electrons. The calculated\naddition spectra exhibit the typical structures of Hund-like shell filling, and\naccount for recent experimental findings. A full three dimensional description\nof Coulomb interaction is found to be essential for predicting the conductance\ncharacteristics of few-electron semiconductor structures."
    },
    {
        "anchor": "Exact solution for the dynamical decoupling of a qubit with telegraph\n  noise: We study the dissipative dynamics of a qubit that is afflicted by classical\nrandom telegraph noise and it is subject to dynamical decoupling. We derive\nexact formulas for the qubit dynamics at arbitrary working points in the limit\nof infinitely strong control pulses (bang-bang control) and we investigate in\ngreat detail the efficiency of the dynamical decoupling techniques both for\nGaussian and non-Gaussian (slow) noise at qubit pure dephasing and at optimal\npoint. We demonstrate that control sequences can be successfully implemented as\ndiagnostic tools to infer spectral proprieties of a few fluctuators interacting\nwith the qubit. The analysis is extended in order to include the effect of\nnoise in the pulses and we give upper bounds on the noise levels that can be\ntolerated in the pulses while still achieving efficient dynamical decoupling\nperformance.",
        "positive": "Local Density of States in Mesoscopic Samples from Scanning Gate\n  Microscopy: We study the relationship between the local density of states (LDOS) and the\nconductance variation $\\Delta G$ in scanning-gate-microscopy experiments on\nmesoscopic structures as a charged tip scans above the sample surface. We\npresent an analytical model showing that in the linear-response regime the\nconductance shift $\\Delta G$ is proportional to the Hilbert transform of the\nLDOS and hence a generalized Kramers-Kronig relation holds between LDOS and\n$\\Delta G$. We analyze the physical conditions for the validity of this\nrelationship both for one-dimensional and two-dimensional systems when several\nchannels contribute to the transport. We focus on realistic Aharonov-Bohm rings\nincluding a random distribution of impurities and analyze the LDOS-$\\Delta G$\ncorrespondence by means of exact numerical simulations, when localized states\nor semi-classical orbits characterize the wavefunction of the system."
    },
    {
        "anchor": "Magnification of spin Hall effect in bilayer electron gas: Spin transport properties of a coupled bilayer electron gas with Rashba\nspin-orbit coupling are studied. The definition of the spin currents in each\nlayer as well as the corresponding continuity-like equations in the bilayer\nsystem are given. The curves of the spin Hall conductivities obtained in each\nlayer exhibit sharp cusps around a particular value of the tunnelling strength\nand the conductivities undergo sign changes across this point. Our\ninvestigation on the impurity effect manifests that an arbitrarily small\nconcentration of nonmagnetic impurities does not suppress the spin Hall\nconductivity to zero in the bilayer system. Based on these features, an\nexperimental scheme is suggested to detect a magnification of the spin Hall\neffect.",
        "positive": "Electronic transport in two-dimensional strained Dirac materials under\n  multi-step Fermi velocity barrier: transfer matrix method for supersymmetric\n  systems: In recent years, graphene and other two-dimensional Dirac materials like\nsilicene, germanene, etc. have been studied from different points of view: from\nmathematical physics, condensed matter physics to high energy physics. In this\nstudy, we utilize both supersymmetric quantum mechanics (SUSY-QM) and transfer\nmatrix method (TTM) to examine electronic transport in two-dimensional Dirac\nmaterials under the influences of multi-step deformation as well as multi-step\nFermi velocity barrier. The effects of multi-step effective mass and multi-step\napplied fields are also taken into account in our investigation. Results show\nthe possibility of modulating the Klein tunneling of Dirac electron by using\nstrain or electric field."
    },
    {
        "anchor": "Diversity enabling equilibration: disorder and the ground state in\n  artificial spin ice: We report a novel approach to the question of whether and how the ground\nstate can be achieved in square artificial spin ices where frustration is\nincomplete. We identify two types of disorder: quenched disorder in the island\nresponse to fields and disorder in the sequence of driving fields. Numerical\nsimulations show that quenched disorder can lead to final states with lower\nenergy, and disorder in the driving fields always lowers the final energy\nattained by the system. We use a network picture to understand these two\neffects: disorder in island responses creates new dynamical pathways, and\ndisorder in driving fields allows more pathways to be followed.",
        "positive": "Hole-flux Composite Fermion Commensurability Oscillations: We report the observation of commensurability oscillations of hole-flux\ncomposite fermions near filling factor $\\nu=1/2$ in a high-mobility\ntwo-dimensional hole system confined to a GaAs quantum well, and subjected to a\nweak, strain-induced, unidirectional periodic potential modulation. The\noscillations, which are consistent with ballistic transport of fully\nspin-polarized composite fermions in a weak periodic effective magnetic field,\nare surprisingly strong and exhibit up to third-order minima. We extract a\nballistic mean-free-path of about 0.2 $\\mu$m for the hole-flux composite\nfermions."
    },
    {
        "anchor": "Nonlinear heat conduction in Coulomb-blockaded quantum dots: We analyze the heat current flowing across interacting quantum dots within\nthe Coulomb blockade regime. Power can be generated by either voltage or\ntemperature biases. In the former case, we find nonlinear contributions to the\nPeltier effect that are dominated by conventional Joule heating for\nsufficiently high voltages. In the latter case, the differential thermal\nconductance shows maxima or minima depending on the energy level position.\nFurthermore, we discuss departures from the Kelvin-Onsager reciprocity relation\nbeyond linear response.",
        "positive": "Anomalous Coulomb drag in electron-hole bilayers: We report Coulomb drag measurements on GaAs-AlGaAs electron-hole bilayers.\nThe two layers are separated by a 10 or 25nm barrier. Below T$\\approx$1K we\nfind two features that a Fermi-liquid picture cannot explain. First, the drag\non the hole layer shows an upturn, which may be followed by a downturn. Second,\nthe effect is either absent or much weaker in the electron layer, even though\nthe measurements are within the linear response regime. Correlated phases have\nbeen anticipated in these, but surprisingly, the experimental results appear to\ncontradict Onsager's reciprocity theorem."
    },
    {
        "anchor": "Spin-Orbit Coupling, Antilocalization, and Parallel Magnetic Fields in\n  Quantum Dots: We investigate antilocalization due to spin-orbit coupling in ballistic GaAs\nquantum dots. Antilocalization that is prominent in large dots is suppressed in\nsmall dots, as anticipated theoretically. Parallel magnetic fields suppress\nboth antilocalization and also, at larger fields, weak localization, consistent\nwith random matrix theory results once orbital coupling of the parallel field\nis included. In situ control of spin-orbit coupling in dots is demonstrated as\na gate-controlled crossover from weak localization to antilocalization.",
        "positive": "Singular Density of States of Disordered Dirac Fermions in the Chiral\n  Models: The Dirac fermion in the random chiral models is studied which includes the\nrandom gauge field model and the random hopping model. We focus on a connection\nbetween continuum and lattice models to give a clear perspective for the random\nchiral models. Two distinct structures of density of states (DoS) around zero\nenergy, one is a power-law dependence on energy in the intermediate energy\nrange and the other is a diverging one at zero energy, are revealed by an\nextensive numerical study for large systems up to $250\\times 250$. For the\nrandom hopping model, our finding of the diverging DoS within very narrow\nenergy range reconciles previous inconsistencies between the lattice and the\ncontinuum models."
    },
    {
        "anchor": "Matter-wave interferometry using a levitated magnetic nanoparticle: The superposition principle is one of the bizarre predictions of quantum\nmechanics. Nevertheless, it has been experimentally verified using electrons,\nphotons, atoms, and molecules. In this article, using a $20~$nm levitated\nferromagnetic FePt nanoparticle, an exotic all optical spin polarization\ntechnique and the matter-wave interferometry, we show that a mesoscopic spatial\nSchrodinger cat can be created. Additionally, we argue that the maximum spatial\nseparation between the delocalized wavepackets can be $25~\\mu m$ and is\nsignificantly larger than the object itself.",
        "positive": "Spin dephasing in III-V nanowires: We use semiclassical Monte Carlo approach to investigate spin polarized\ntransport in InP and InSb nanowires. Spin dephasing in III-V channels is caused\ndue to D'yakonov- Perel (DP) relaxation and due to Elliott-Yafet (EY)\nrelaxation. The DP relaxation occurs because of bulk inversion asymmetry\n(Dresselhaus spin-orbit interaction) and structural inversion asymmetry (Rashba\nspin-orbit interaction). The injection polarization direction studied is that\nalong the length of the channel. The dephasing rate is found to be very strong\nfor InSb as compared to InP which has larger spin dephasing lengths. The\nensemble averaged spin components vary differently for both InP and InSb\nnanowires. The steady state spin distribution also shows a difference between\nthe two III-V nanowires."
    },
    {
        "anchor": "Electric field tunable multi-state tunnel magnetoresistances in 2D van\n  der Waals magnetic heterojunctions: Magnetic tunnel junction (MTJ) based on van der Waals (vdW) magnetic layers\nhas been found to present excellent tunneling magnetoresistance (TMR) property,\nwhich has great potential applications in field sensing, non-volatile magnetic\nrandom access memories, and spin logics. Although MTJs composed of multilayer\nvdW magnetic homojunction have been extensively investigated, the ones composed\nof vdW magnetic heterojunction is still to be explored. Here we use\nfirst-principles approaches to reveal that the magnetic heterojunction MTJs\nhave much more distinguishable TMR values than the homojunction ones. In the\nMTJ composed of bilayer CrI3/bilayer Cr2Ge2Te6 heterojunction, we find there\nare eight stable magnetic states, leading to six distinguishable electronic\nresistances. As a result, five sizable TMRs larger than 300% can be obtained\n(the maximum TMR is up to 620,000%). Six distinguishable memories are obtained\nwhich is two times larger than that of a four-layered homojunction MTJ. The\nunderlying relationships among magnetic state, spin-polarized band structures,\nand transmission spectrums are further revealed to explain the multiple TMR\nvalues. We also find that the magnetic states and thus TMRs can be efficiently\nmodulated by an external electric field. This study opens an avenue to the\ndesign of high-performance MTJ devices based on vdW heterojunctions.",
        "positive": "Enhanced current noise correlations in a Coulomb-Majorana device: Majorana bound states (MBSs) nested in a topological nanowire are predicted\nto manifest nonlocal correlations in the presence of a finite energy splitting\nbetween the MBSs. However, the signal of the nonlocal correlations has not yet\nbeen detected in experiments. A possible reason is that the energy splitting is\ntoo weak and seriously affected by many system parameters. Here we investigate\nthe charging energy induced nonlocal correlations in a hybrid device of MBSs\nand quantum dots. The nanowire that hosts the MBSs is assumed in proximity to a\nmesoscopic superconducting island with a finite charging energy. Each end of\nthe nanowire is coupled to one lead via a quantum dot with resonant levels.\nWith a floating superconducting island, the devices shows a negative\ndifferential conductance and giant super-Poissonian shot noise, due to the\ninterplay between the nonlocality of the MBSs and dynamical Coulomb blockade\neffect. When the island is strongly coupled to a bulk superconductor, the\ncurrent cross correlations at small lead chemical potentials are negative by\ntuning the dot energy levels. In contrast, the cross correlation is always\npositive in a non-Majorana setup. This difference may provide a signature for\nthe existence of the MBSs."
    },
    {
        "anchor": "Dynamics of quasiholes and quasiparticles at the edges of small lattices: We study quench dynamics of bosonic fractional quantum Hall systems in small\nlattices with cylindrical boundary conditions and low particle density. The\nstates studied have quasiholes or quasiparticles relative to the bosonic\nLaughlin state at half filling. Pinning potentials are placed at edge sites (or\nsites close to the edges) and are then turned off. Because the edges of\nfractional quantum Hall systems host chiral edge modes, we expect chiral\ndynamics, with motion in one direction for positive potentials pinning\nquasiholes, and motion in the other direction for negative potentials pinning\nquasiparticles. We numerically show that chiral motion of the density\ndistribution is observed and robust for the case with positive potentials\n(quasiholes), but that there is no noticeable chiral motion for negative\npotentials (quasiparticles). The comparison of the numerical ground states with\nmodel lattice Laughlin wavefunctions suggests that both positive and negative\npotentials do create and pin anyons that are not necessarily well-separated on\nsmall lattices. Initializing the dynamics with the model state also shows the\nlack of chiral dynamics of quasiparticles. Our results suggest that, in small\nlattices with low particle density, quasiparticles are strongly adversely\naffected in dynamical processes, whereas quasiholes are dynamically robust.",
        "positive": "Efficient Chebyshev polynomial approach to quantum conductance\n  calculations: Application to twisted bilayer graphene: In recent years, Chebyshev polynomial expansions of tight-binding Green's\nfunctions have been successfully applied to the study of a wide range of\nspectral and transport properties of materials. However, the application of the\nChebyshev approach to the study of quantum transport properties of\nnoninteracting mesoscopic systems with leads has been hampered by the lack of a\nsuitable Chebyshev expansion of Landaeur's formula or one of its equivalent\nformulations in terms of Green's functions in Keldysh's perturbation theory.\nHere, we tackle this issue by means of a hybrid approach that combines the\nefficiency of Chebyshev expansions with the convenience of complex absorbing\npotentials to calculate the conductance of two-terminal devices in a\ncomputationally expedient and accurate fashion. The versatility of the approach\nis demonstrated for mesoscopic twisted bilayer graphene (TBG) devices with up\nto $2.3\\times10^6$ atomic sites. Our results highlight the importance of\nmoir\\'e effects, interlayer scattering events and twist-angle disorder in\ndetermining the conductance curves in devices with a small twist angle near the\nTBG magic angle $\\theta_m \\approx 1.1^\\circ$."
    },
    {
        "anchor": "Angular momentum-dependent topological transport and its experimental\n  realization using a transmission line network: Novel classical wave phenomenon analogs of the quantum spin Hall effect are\nmostly based on the construction of pseudo-spins. Here we show that the\nnon-trivial topology of a system can also be realized using orbital angular\nmomentum through angular-momentum-orbital coupling. The idea is illustrated\nwith a tight-binding model and experimentally demonstrated with a transmission\nline network. We show experimentally that even a very small network cluster\nexhibits one-way topological edge states, and their properties can be described\nin terms of local Chern numbers. Our work provides a new mechanism to realize\ncounterparts of the quantum spin Hall effect in classical waves and may offer\ninsights for other systems.",
        "positive": "Double refraction and spin splitter in a normal-hexagonal semiconductor\n  junction: In analogy with light refraction at optical boundary, ballistic electrons\nalso undergo refraction when propagate across a semiconductor junction.\nEstablishing a negative refractive index in conventional optical materials is\ndifficult, but the realization of negative refraction in electronic system is\nconceptually straightforward, which has been verified in graphene p-n junctions\nin recent experiments. Here, we propose a model to realize double refraction\nand double focusing of electric current by a normal-hexagonal semiconductor\njunction. The double refraction can be either positive or negative, depending\non the junction being n-n type or p-n type. Based on the valley-dependent\nnegative refraction, a spin splitter (valley splitter) is designed at the p-n\njunction system, where the spin-up and spin-down electrons are focused at\ndifferent regions. These findings may be useful for the engineering of double\nlenses in electronic system and have underlying application of spin splitter in\nspintronics."
    },
    {
        "anchor": "Cloaking of Arbitrarily-Shaped Objects with Homogeneous Coatings: We present a theory for the cloaking of arbitrarily-shaped objects and\ndemonstrate electromagnetic scattering-cancellation through designed\nhomogeneous coatings. First, in the small-particle limit, we expand the dipole\nmoment of a coated object in terms of its resonant modes. By zeroing the\nnumerator of the resulting rational function, we accurately predict the\npermittivity values of the coating layer that abates the total scattered power.\nThen, we extend the applicability of the method beyond the small-particle\nlimit, deriving the radiation corrections of the scattering-cancellation\npermittivity within a perturbation approach. Our method permits the design of\ninvisibility cloaks for irregularly-shaped devices such as complex sensors and\ndetectors.",
        "positive": "Noise-enabled precision measurements of a Duffing nanomechanical\n  resonator: We report quantitative experimental measurements of the nonlinear response of\na radiofrequency mechanical resonator, with very high quality factor, driven by\na large swept-frequency force. We directly measure the noise-free transition\ndynamics between the two basins of attraction that appear in the nonlinear\nregime, and find good agreement with those predicted by the one-dimensional\nDuffing equation of motion. We then measure the response of the transition\nrates to controlled levels of white noise, and extract the activation energy\nfrom each basin. The measurements of the noise-induced transitions allow us to\nobtain precise values for the critical frequencies, the natural resonance\nfrequency, and the cubic nonlinear parameter in the Duffing oscillator, with\ndirect applications to high sensitivity parametric sensors based on these\nresonators."
    },
    {
        "anchor": "Influence of nonlocal damping on the field-driven domain wall motion: We derive the complete expression of nonlocal damping in noncollinear\nmagnetization due to the nonuniform spin current pumped by precessional\nmagnetization and incorporate it into a generalized Thiele equation to study\nits effects on the dynamics of the transverse and vortex domain walls (DWs) in\nferromagnetic nanowires. We demonstrate that the transverse component of\nnonlocal damping slows down the field-driven DW propagation and increases the\nWalker breakdown field whereas it is neglected in many previous works in\nliterature. The experimentally measured DW mobility variation with the damping\ntuned by doping with heavy rare-earth elements that had discrepancy from\nmicromagnetic simulation are now well understood with the nonlocal damping. Our\nresults suggest that the nonlocal damping should be properly included as a\nprerequisite for quantitative studies of current-induced torques in\nnoncollinear magnetization.",
        "positive": "Multi-Control Over Graphene-Molecule Hetereo-Junctions: The vertical configuration is a powerful tool recently developed\nexperimentally to investigate field effects in quasi 2D systems. Prototype\ngraphene-based vertical tunneling transistors can achieve an extraordinary\ncontrol over current density utilizing gate voltages. In this work we study\ntheoretically vertical tunneling junctions that consist of a monolayer of\nphoto-switchable aryl-azobenzene molecules of sandwiched between two sheets of\ngraphene. Azobenzene molecules transform between {\\it trans} and {\\it cis}\nconformations upon photoexcitation, thus adding a second knob that enhances\ncontrol over physical properties of the junction. Using first-principles\nmethods within the density functional framework, we perform simulations with\nthe inclusion of field effects for both {\\it trans} and {\\it cis}\nconfigurations. We find that the interference of interface states resulting\nfrom molecule-graphene interactions at the Fermi energy introduces a dual-peak\npattern in the transmission functions and dominates the transport properties of\ngate junctions, shedding new light on interfacial processes."
    },
    {
        "anchor": "Geometrical effects on the downstream conductance in\n  quantum-Hall--superconductor hybrid systems: We consider a quantum Hall (QH) region in contact with a superconductor (SC),\ni.e., a QH-SC junction. Due to successive Andreev reflections, the QH-SC\ninterface hosts hybridized electron and hole edge states called chiral Andreev\nedge states (CAES). We theoretically study the transport properties of these\nCAES by using a microscopic, tight-binding model. We find that the transport\nproperties strongly depend on the contact geometry and the value of the filling\nfactor. We notice that it is necessary to add local barriers at the corners of\nthe junction in order to reproduce such properties, when using effective\none-dimensional models.",
        "positive": "Self Assembled II-VI Magnetic Quantum Dot as a Voltage-Controlled\n  Spin-Filter: A key element in the emergence of a full spintronics technology is the\ndevelopment of voltage controlled spin filters to selectively inject carriers\nof desired spin into semiconductors. We previously demonstrated a prototype of\nsuch a device using a II-VI dilute-magnetic semiconductor quantum well which,\nhowever, still required an external magnetic field to generate the level\nsplitting. Recent theory suggests that spin selection may be achievable in\nII-VI paramagnetic semiconductors without external magnetic field through local\ncarrier mediated ferromagnetic interactions. We present the first experimental\nobservation of such an effect using non-magnetic CdSe self-assembled quantum\ndots in a paramagnetic (Zn,Be,Mn)Se barrier."
    },
    {
        "anchor": "Ballistic transport in induced one-dimensional hole systems: We have fabricated and studied a ballistic one-dimensional p-type quantum\nwire using an undoped AlGaAs/GaAs heterostructure. The absence of modulation\ndoping eliminates remote ionized impurity scattering and allows high mobilities\nto be achieved over a wide range of hole densities, and in particular, at very\nlow densities where carrier-carrier interactions are strongest. The device\nexhibits clear quantized conductance plateaus with highly stable gate\ncharacteristics. These devices provide opportunities for studying spin-orbit\ncoupling and interaction effects in mesoscopic hole systems in the strong\ninteraction regime where rs > 10.",
        "positive": "Magnetotunneling spectroscopy of mesoscopic correlations in\n  two-dimensional electron systems: An approach to experimentally exploring electronic correlation functions in\nmesoscopic regimes is proposed. The idea is to monitor the mesoscopic\nfluctuations of a tunneling current flowing between the two layers of a\nsemiconductor double-quantum-well structure. From the dependence of these\nfluctuations on external parameters, such as in-plane or perpendicular magnetic\nfields, external bias voltages, etc., the temporal and spatial dependence of\nvarious prominent correlation functions of mesoscopic physics can be\ndetermined. Due to the absence of spatially localized external probes, the\nmethod provides a way to explore the interplay of interaction and localization\neffects in two-dimensional systems within a relatively unperturbed environment.\nWe describe the theoretical background of the approach and quantitatively\ndiscuss the behavior of the current fluctuations in diffusive and ergodic\nregimes. The influence of both various interaction mechanisms and localization\neffects on the current is discussed. Finally a proposal is made on how, at\nleast in principle, the method may be used to experimentally determine the\nrelevant critical exponents of localization-delocalization transitions."
    },
    {
        "anchor": "Time-reversal symmetric topological metal: Topological metals possess gapless band structures accompanied with\nnontrivial edge states. Topological metals are created from the topological\ninsulators by adjusting the magnetic flux. Here we propose the time-reversal\nsymmetry protected topological metal without employing the magnetic flux.\nTopological metallic phase presents although the Chern number vanishes. In the\ntopologically nontrivial phase, three different cases in the metallic phase are\ndistinguished from the band-touching and in-gap features of the topological\nedge states. These findings shed light on the time-reversal symmetric\ntopological metals and greatly simplify the realization of topological metals.",
        "positive": "Spin Nernst effect in the absence of a magnetic field: We study the spin Nernst effect of a mesoscopic four-terminal cross-bar\ndevice with the Rashba spin-orbit interaction (SOI) in the absence of a\nmagnetic field. The interplay between the spin Nernst effect and the seebeck\ncoefficient is investigated for a wide range of the Rashba SOI. When no peaks\nappeared in the seebeck coefficient, an oscillatory spin Nernst effect still\noccurs. In addition, the disorder effect on the spin Nernst effect is also\nstudied. We find that the spin Nernst effect can be enhanced up to threefold by\ndisorder. Besides, due to the interface effect, the counter propagating of the\ncharge current to the direction of the temperature gradient is possible for a\nnonuniform system."
    },
    {
        "anchor": "Theory of tunneling transport in periodic chains: We present an extended discussion of a recently proposed theoretical approach\nfor off-resonance tunneling transport. The proofs and the arguments are\nexplained at length and simple analogies and illustrations are used where\npossible. The result is an analytic formula for the asymptotic tunneling\nconductance which involves the overlap of three well defined physical\nquantities. We argue that the formula can be used to gain fresh insight into\nthe tunneling transport characteristics of various systems. The formalism is\napplied here to molecular devices consisting of planar phenyl chains connected\nto gold electrodes via amine linkers.",
        "positive": "Large Quantum Anomalous Hall Effect in Spin-Orbit Proximitized\n  Rhombohedral Graphene: The quantum anomalous Hall effect (QAHE) is a robust topological phenomenon\nthat features quantized Hall resistance at zero magnetic field. Here we report\nthe observation of the QAHE in a rhombohedral pentalayer graphene/monolayer WS2\nheterostructure. Distinct from all existing QAHE systems, this system has\nneither magnetic element nor moir\\'e superlattice effect. The QAH states emerge\nat charge neutrality and feature Chern numbers C = +-5 at temperatures up to\nabout 1.5 K. This large QAHE in our system arises from the synergy of the\nelectron correlation effect in intrinsic flat bands of pentalayer graphene, the\ngate-tuning effect that breaks the layer/spin-degeneracy, and the\nproximity-induced Ising spin-orbit-coupling (SOC) effect that further lifts the\nvalley-degeneracy. Our experiment demonstrates the great potential of\ncrystalline two-dimensional materials for intertwined electron correlation and\nband topology physics, and points to engineering chiral Majorana edge states\ntowards topological quantum computation."
    },
    {
        "anchor": "Ballistic molecular transport through two-dimensional channels: Gas permeation through nanoscale pores is ubiquitous in nature and plays an\nimportant role in a plethora of technologies. Because the pore size is\ntypically smaller than the mean free path of gas molecules, their flow is\nconventionally described by the Knudsen theory that assumes diffuse reflection\n(random-angle scattering) at confining walls. This assumption has proven to\nhold surprisingly well in experiment, and only a few cases of partially\nspecular (mirror-like) reflection are known. Here we report gas transport\nthrough angstrom-scale channels with atomically-flat walls and show that\nsurface scattering can be both diffuse or specular, depending on fine details\nof the surface atomic landscape, and quantum effects contribute to the\nspecularity at room temperature. The channels made from graphene or boron\nnitride allow a helium gas flow that is orders of magnitude faster than\nexpected from the theory. This is explained by specular surface scattering,\nwhich leads to ballistic transport and frictionless gas flow. Similar channels\nbut with molybdenum disulfide walls exhibit much slower permeation that remains\nwell described by Knudsen diffusion. The difference is attributed to stronger\natomic corrugations at MoS2 surfaces, which are similar in height to the size\nof transported atoms and their de Broglie wavelength. The importance of the\nlatter, matter-wave contribution is corroborated by the observation of a\nreversed isotope effect in which the mass flow of hydrogen is notably higher\nthan that of deuterium, in contrast to the relation expected for classical\nflows. Our results provide insights into atomistic details of molecular\npermeation, which so far could be accessed only in simulations, and show a\npossibility of studying gas transport under a controlled confinement comparable\nto the quantum-mechanical size of atoms.",
        "positive": "Anomalous behavior of 1/f noise in graphene near the charge neutrality\n  point: We investigate the noise in single layer graphene devices from equilibrium to\nfar from equilibrium and found that the 1/f noise shows an anomalous dependence\non the source-drain bias voltage (VSD). While the Hooge relation is not the\ncase around the charge neutrality point, we found that it is recovered at very\nlow VSD region. We propose that the depinning of the electron-hole puddles is\ninduced at finite VSD, which may explain this anomalous noise behavior."
    },
    {
        "anchor": "Phonon momentum and damping of mechanical resonators: The concept of physical momentum associated to phonons in a crystal,\ncomplemented with some fundamental reasoning, implies measurable effects in\ncrystals even at a macroscopic scale. We show that, in close analogy with the\ntransfer of momentum in the kinetic theory of gases, physical momentum carried\nby of phonons couples the thermal and the velocity field in a vibrating\ncrystal. Therefore an heat flow applied to a vibrating crystal can sustain or\ndamp the oscillation, depending on the interplay between the temperature and\nthe velocity gradient. We derive the general equations of this effect and show\nthat its experimental confirmation is within reach of current technology.",
        "positive": "Warming in systems with discrete spectrum: spectral diffusion of two\n  dimensional electrons in magnetic field: Warming in complex physical systems, in particular global warming, attracts\nsignificant contemporary interest. It is essential, therefore, to understand\nbasic physical mechanisms leading to overheating. It is well known that\napplication of an electric field to conductors heats electric charge carriers.\nOften an elevated electron temperature describes the result of the heating.\nThis paper demonstrates that an electric field applied to a conductor with\ndiscrete electron spectrum produces a non-equilibrium electron distribution,\nwhich cannot be described by temperature. Such electron distribution changes\ndramatically the conductivity of highly mobile two dimensional electrons in a\nmagnetic field, forcing them into a state with a zero differential resistance.\nMost importantly the results demonstrate that, in general, the effective\noverheating in the systems with discrete spectrum is significantly stronger\nthan the one in systems with continuous and homogeneous distribution of the\nenergy levels at the same input power."
    },
    {
        "anchor": "Constructive role of non-adiabaticity for quantized charge pumping: We investigate a recently developed scheme for quantized charge pumping based\non single-parameter modulation. The device was realized in an AlGaAl-GaAs gated\nnanowire. It has been shown theoretically that non-adiabaticity is\nfundamentally required to realize single-parameter pumping, while in previous\nmulti-parameter pumping schemes it caused unwanted and less controllable\ncurrents. In this paper we demonstrate experimentally the constructive and\ndestructive role of non-adiabaticity by analysing the pumping current over a\nbroad frequency range.",
        "positive": "The Role of Spin-Flip Collisions in a Dark Exciton Condensate: We show that a Bose-Einstein condensate consisting of dark excitons forms in\nGaAs coupled quantum wells at low temperatures. We find that the condensate\nextends over hundreds of micrometers, well beyond the optical excitation\nregion, and is limited only by the boundaries of the mesa. We show that the\ncondensate density is determined by spin flipping collisions among the\nexcitons, which convert dark excitons into bright ones. The suppression of this\nprocess at low temperature yields a density buildup, manifested as a\ntemperature-dependent blueshift of the exciton emission line. Measurements\nunder in-plane magnetic field allows us to preferentially modify the bright\nexcitons density, and determine their role in the system dynamics. We find that\ntheir interaction with the condensate leads to its depletion. We present a\nsimple rate equations model, which well-reproduces the observed temperature,\npower, and magnetic field dependence of the exciton density."
    },
    {
        "anchor": "Electron-hole coexistence in disordered graphene probed by high-field\n  magneto-transport: We report on magneto-transport measurement in disordered graphene under\npulsed magnetic field of up to 57T. For large electron or hole doping, the\nsystem displays the expected anomalous Integer Quantum Hall Effect (IQHE)\nspecific to graphene up to filling factor $\\nu=2$. In the close vicinity of the\ncharge neutrality point, the system breaks up into co-existing puddles of holes\nand electrons, leading to a vanishing Hall and finite longitudinal resistance\nwith no hint of divergence at very high magnetic field. Large resistance\nfluctuations are observed near the Dirac point. They are interpreted as the the\nnatural consequence of the presence of electron and hole puddles. The magnetic\nfield at which the amplitude of the fluctuations are the largest is directly\nlinked to the mean size of the puddles.",
        "positive": "Conduction electrons and the decoherence of solid state qubits: We study the dynamics of impurity bound electrons interacting with a bath of\nconduction band electrons in a semiconductor. Only the exchange interaction is\nconsidered. We derive master equations for the density matrices of single and\ntwo qubit systems under the usual Born and Markov approximations. The bath\nmediated RKKY interaction in the two qubit case arises naturally. It leads to\nan energy shift significant only when the ratio ($R_{T}$) of the inter-qubit\ndistance to the thermal deBroglie wavelength of the bath electrons is small.\nThis bath mediated interaction also has a profound impact on the decoherence\ntimes; the effect decreases monotonically with $R_{T}$."
    },
    {
        "anchor": "Collapse of electrons to a donor cluster in SrTiO$_3$: It is known that a nucleus with charge $Ze$ where $Z>170$ creates\nelectron-positron pairs from the vacuum. These electrons collapse onto the\nnucleus resulting in a net charge $Z_n<Z$ while the positrons are emitted. This\neffect is due to the relativistic dispersion law. The same reason leads to the\ncollapse of electrons to the charged impurity with a large charge number $Z$ in\nnarrow-band gap semiconductors and Weyl semimetals as well as graphene. In this\npaper, a similar effect of electron collapse and charge renormalization is\nfound for donor clusters in SrTiO$_3$ (STO), but with a very different origin.\nAt low temperatures, STO has an enormously large dielectric constant. Because\nof this, the nonlinear dielectric response becomes dominant when the electric\nfield is not too small. We show that this leads to the collapse of surrounding\nelectrons into a charged spherical donor cluster with radius $R$ when its total\ncharge number $Z$ exceeds a critical value $Z_c\\simeq R/a$ where $a$ is the\nlattice constant. Using the Thomas-Fermi approach, we find that the net charge\n$Z_ne$ grows with $Z$ until $Z$ exceeds another value $Z^*\\simeq(R/a)^{9/7}$.\nAfter this point, $Z_n$ remains $\\sim Z^*$. We extend our results to the case\nof long cylindrical clusters. Our predictions can be tested by creating discs\nand stripes of charge on the STO surface.",
        "positive": "Quantum critical scaling in magnetic field near the Dirac point in\n  graphene: Motivated by the recent measurement of the activation energy at the quantum\nHall state at the filling factor f=1 in graphene we discuss the scaling of the\ninteraction-induced gaps in vicinity of the Dirac point with the magnetic\nfield. The gap at f=1 is shown to be bounded from above by E(1)/C, where E(n)\nare the Landau level energies and C = 5.985 + O(1/N) is a universal number. The\nuniversal scaling functions are computed exactly for a large number of Dirac\nfermions N. We find a sublinear dependence of the gap at the laboratory\nmagnetic fields for realistic values of short-range repulsion between\nelectrons, and in quantitative agreement with observation."
    },
    {
        "anchor": "Microwave Photon Detector in Circuit QED: Quantum optical photodetection has occupied a central role in understanding\nradiation-matter interactions. It has also contributed to the development of\natomic physics and quantum optics, including applications to metrology,\nspectroscopy, and quantum information processing. The quantum microwave regime,\noriginally explored using cavities and atoms, is seeing a novel boost with the\ngeneration of nonclassical propagating fields in circuit quantum\nelectrodynamics (QED). This promising field, involving potential developments\nin quantum information with microwave photons, suffers from the absence of\nphotodetectors. Here, we design a metamaterial composed of discrete\nsuperconducting elements that implements a high-efficiency microwave photon\ndetector. Our design consists of a microwave guide coupled to an array of\nmetastable quantum circuits, whose internal states are irreversibly changed due\nto the absorption of photons. This proposal can be widely applied to different\nphysical systems and can be generalized to implement a microwave photon\ncounter.",
        "positive": "Versatile scanning tunneling microscopy with 120ps time resolution: We describe a fully ultra-high vacuum compatible scanning tunneling\nmicroscope (STM) optimized for radio-frequency signals. It includes in-situ\nexchangeable tips adapted to high frequency cabling and a standard sample\nholder, which offer access to the whole range of samples typically investigated\nby STM. We demonstrate a time resolution of 120 ps using the nonlinear\nI(V)-characteristic of the surface of highly oriented pyrolithic graphite. We\nprovide atomically resolved images in pulse mode related to a spatially varying\nnonlinearity of the local density of states of the sample, thus, demonstrating\nthe possible spatial resolution of the instrument in pulse mode. Analysis of\nthe noise reveals that changes in the tunneling junction of 50 pA are\ndynamically detectable at 120 ps time resolution."
    },
    {
        "anchor": "A newly-designed femtosecond KBe$_2$BO$_3$F$_2$ device with pulse\n  duration down to 55 fs for time- and angle-resolved photoemission\n  spectroscopy: Developing a widely tunable vacuum ultraviolet (VUV) source with sub-100\nfemtoseconds (fs) pulse duration is critical for ultrafast pump-probe\ntechniques such as time- and angle-resolved photoemission spectroscopy\n(TrARPES). While a tunable probe source with photon energy of 5.3 - 7.0 eV has\nbeen recently implemented for TrARPES by using a KBe$_2$BO$_3$F$_2$ (KBBF)\ndevice, the time resolution of 280 - 320 fs is still not ideal, which is mainly\nlimited by the duration of the VUV probe pulse generated by the KBBF device.\nHere, by designing a new KBBF device which is specially optimized for fs\napplications, an optimum pulse duration of 55 fs is obtained after systematic\ndiagnostics and optimization. More importantly, a high time resolution of 81 -\n95 fs is achieved for TrARPES measurements covering the probe photon energy\nrange of 5.3 - 7.0 eV, making it particularly useful for investigating the\nultrafast dynamics of quantum materials. Our work extends the application of\nKBBF device to ultrafast pump-probe techniques with the advantages of both\nwidely tunable VUV source and ultimate time resolution.",
        "positive": "Asymmetry of localised states in a single quantum ring: polarization\n  dependence of excitons and biexcitons: We performed spectroscopic studies of a single GaAs quantum ring with an\nanisotropy in the rim height. The presence of an asymmetric localised state was\nsuggested by the adiabatic potential. The asymmetry was investigated in terms\nof the polarization dependence of excitons and biexcitons, where a large energy\ndi erence (0.8 meV) in the exciton emission energy for perpendicular\npolarizations was observed and the oscillator strengths were also compared\nusing the photoluminescence decay rate. For perpendicular polarizations the\nbiexciton exhibits twice the energy di erence seen for the exciton, a fact that\nmay be attributed to a possible change in the selection rules for the lowered\nsymmetry."
    },
    {
        "anchor": "Structured Back Gates for High-Mobility Two-Dimensional Electron Systems\n  Using Oxygen Ion Implantation: We present a new approach of back gate patterning that is compatible with the\nrequirements of highest mobility molecular beam epitaxy. Contrary to common\nback gating techniques, our method is simple, reliable and can be scaled up for\nentire wafers. The back gate structures are defined by local oxygen\nimplantation into a silicon doped GaAs epilayer, which suppresses the\nconductance without affecting the surface quality.",
        "positive": "Light-matter correlations in Quantum Floquet engineering: Quantum Floquet engineering seeks to externally control systems by means of\nquantum fields. However, to faithfully capture the physics at arbitrary\ncoupling, a gauge-invariant description of light-matter interaction is\nrequired, which makes the Hamiltonian highly nonlinear in the photonic\noperators. Here we provide a non-perturbative truncation scheme, which is valid\nfor arbitrary coupling strength. With this framework, we investigate the role\nof light-matter correlations, which are absent in systems described by\nsemiclassical Floquet engineering. We find that even in the high-frequency\nregime, their importance can be crucial, in particular for the topological\nproperties of the system. As an example we show that in an SSH chain coupled to\na cavity, light-matter correlations break chiral symmetry, strongly affecting\nthe robustness of its edge states. In addition, we show how light-matter\ncorrelations are imprinted in the photonic spectral function, and discuss their\nrelation with the topology of the photonic bands."
    },
    {
        "anchor": "Quantum-classical approach to spin and charge pumping and the ensuing\n  radiation in THz spintronics: Example of ultrafast-light-driven Weyl\n  antiferromagnet Mn$_3$Sn: The interaction of fs light pulses with magnetic materials has been intensely\nstudied for more than two decades in order to understand ultrafast\ndemagnetization in single magnetic layers or THz emission from their bilayers\nwith nonmagnetic spin-orbit (SO) materials. Here we develop a multiscale\nquantum-classical formalism -- where conduction electrons are described by\nquantum master equation of the Lindblad type; classical dynamics of local\nmagnetization is described by the Landau-Lifshitz-Gilbert (LLG) equation; and\nincoming light is described by classical vector potential while outgoing\nelectromagnetic radiation is computed using Jefimenko equations for retarded\nelectric and magnetic fields -- and apply it a bilayer of antiferromagnetic\nWeyl semimetal Mn$_3$Sn with noncollinear local magnetization in contact with\nSO-coupled nonmagnetic material. Our QME+LLG+Jefimenko scheme makes it possible\nto understand how fs light pulse generates directly spin and charge pumping and\nelectromagnetic radiation by the latter, including both odd and even high\nharmonics (of the pulse center frequency) up to order $n \\le 7$. The directly\npumped spin current then exert spin torque on local magnetization whose\ndynamics, in turn, pumps additional spin and charge currents radiating in the\nTHz range. By switching on and off LLG dynamics and SO couplings, we unravel\nwhich microscopic mechanism contribute the most to emitted THz radiation --\ncharge pumping by local magnetization of Mn$_3$Sn in the presence of its\nintrinsic SO coupling is far more important than standardly assumed (for other\ntypes of magnetic layers) spin pumping and subsequent spin-to-charge conversion\nwithin the neighboring nonmagnetic SO-coupled material.",
        "positive": "Conductance of a SET with a retarded dielectric layer in the gate\n  capacitor: We study conductance of a single electron transistor (SET) with a\nferroelectric (or dielectric) layer placed in the gate capacitor. We assume\nthat ferroelectric (FE) has a retarded response with arbitrary relaxation time.\nWe show that in the case of \"fast\" but still retarded response of the FE\n(dielectric) layer an additional contribution to the Coulomb blockade effect\nappears leading to the suppression of the SET conductance. We take into account\nfluctuations of the FE (dielectric) polarization using Monte-Carlo simulations.\nFor \"fast\" FE these fluctuations partially suppress the additional Coulomb\nblockade effect. Using Monte-Carlo simulations we study the transition from\n\"fast\" to \"slow\" FE. For high temperatures the peak value of the SET\nconductance is almost independent of the FE relaxation time. For temperatures\nclose to the FE Curie temperature the conductance peak value non-monotonically\ndepends on the FE relaxation time. A maximum appears when the FE relaxation\ntime is of the order of the SET discharging time. Below the Curie point the\nconductance peak value decreases with increasing the FE relaxation time. The\nconductance shows the hysteresis behavior for any FE relaxation time at\ntemperatures below the FE transition point. We show that conductance hysteresis\nis robust against FE internal fluctuations."
    },
    {
        "anchor": "Interaction effects at the magnetic-field induced metal-insulator\n  transition in Si/SiGe superlattices: A metal-insulator transition was induced by in-plane magnetic fields up to 27\nT in homogeneously Sb-doped Si/SiGe superlattice structures. The localisation\nis not observed for perpendicular magnetic fields. A comparison with\nmagnetoconductivity investigations in the weakly localised regime shows that\nthe delocalising effect originates from the interaction-induced spin-triplet\nterm in the particle-hole diffusion channel. It is expected that this term,\npossibly together with the singlet particle-particle contribution, is of\ngeneral importance in disordered n-type Si bulk and heterostructures.",
        "positive": "Light-matter interaction in doped microcavities: We discuss theoretically the light-matter coupling in a microcavity\ncontaining a quantum well with a two-dimensional electron gas. The high density\nlimit where the bound exciton states are absent is considered. The matrix\nelement of interband optical absorbtion demonstrates the Mahan singularity due\nto strong Coulomb effect between the electrons and a photocreated hole. We\nextend the non-local dielectric response theory to calculate the quantum well\nreflection and transmission coefficients, as well as the microcavity\ntransmission spectra. The new eigenmodes of the system are discussed. Their\nimplications for the steady state and time resolved spectroscopy experiments\nare analyzed."
    },
    {
        "anchor": "Reservoir Computing on Spin-Torque Oscillator Array: We numerically study reservoir computing on a spin-torque oscillator (STO)\narray, describing the magnetization dynamics of the STO array by a nonlinear\noscillator model. The STOs exhibit synchronized oscillation due to coupling by\nmagnetic dipolar fields. We show that reservoir computing can be performed\nusing the synchronized oscillation state. The performance can be improved by\nincreasing the number of STOs. The performance becomes highest at the boundary\nbetween the synchronized and disordered states. Using an STO array, we can\nachieve higher performance than that of an echo-state network with similar\nnumber of units. This result indicates that STO arrays are promising for\nhardware implementation of reservoir computing.",
        "positive": "Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane\n  Magnetoresistance in High-Mobility (100) Si Inversion Layers: Comment on: Weak Anisotropy and Disorder Dependence of the In-Plane\nMagnetoresistance in High-Mobility (100) Si Inversion Layers"
    },
    {
        "anchor": "Gate-induced insulating state in bilayer graphene devices: The potential of graphene-based materials consisting of one or a few layers\nof graphite for integrated electronics originates from the large\nroom-temperature carrier mobility in these systems (approx. 10,000 cm2/Vs).\nHowever, the realization of electronic devices such as field-effect transistors\nwill require controlling and even switching off the electrical conductivity by\nmeans of gate electrodes, which is made difficult by the absence of a bandgap\nin the intrinsic material. Here, we demonstrate the controlled induction of an\ninsulating state - with large suppression of the conductivity - in bilayer\ngraphene, by using a double-gate device configuration that allows an electric\nfield to be applied perpendicular to the plane. The dependence of the\nresistance on temperature and electric field, and the absence of any effect in\na single-layer device, strongly suggest that the gate-induced insulating state\noriginates from the recently predicted opening of a bandgap between valence and\nconduction bands.",
        "positive": "Phase-coherent transport in InN nanowires of various sizes: We investigate phase-coherent transport in InN nanowires of various diameters\nand lengths. The nanowires were grown by means of plasma-assisted molecular\nbeam epitaxy. Information on the phase-coherent transport is gained by\nanalyzing the characteristic fluctuation pattern in the magneto-conductance.\nFor a magnetic field oriented parallel to the wire axis we found that the\ncorrelation field mainly depends on the wire cross section, while the\nfluctuation amplitude is governed by the wire length. In contrast, if the\nmagnetic field is oriented perpendicularly, for wires longer than approximately\n200 nm the correlation field is limited by the phase coherence length. Further\ninsight into the orientation dependence of the correlation field is gained by\nmeasuring the conductance fluctuations at various tilt angles of the magnetic\nfield."
    },
    {
        "anchor": "Contact resistance assessment and high-frequency performance projection\n  of black phosphorus field-effect transistor technologies: In this work, an evaluation of the contact quality of black phosphorus (BP)\nfield-effect transistors (FETs) from different technologies previously reported\nis performed by means of an efficient and reliable contact resistance\nextraction methodology based on individual device practical characteristics. A\ngood agreement is achieved between the extracted values with the Y-function\nmethod used here and reference values obtained with other methods considering\ninternal values as well as with more expensive methods involving fabricated\ntest structures. The method enables a direct evaluation of different steps in\nthe same technology and it embraces the temperature dependence of the contact\ncharacteristics. Channel phenomena have no impact on the extracted contact\nresistance values. High-frequency performance projections are obtained for\nfabricated devices based on the extracted contact resistance.",
        "positive": "Towards low-loss telecom-wavelength photonic devices by designing\n  GaBi$_{x}$As$_{1-x}$/GaAs core$-$shell nanowires: Nanowires are versatile nanostructures, which allow an exquisite control over\nbandgap energies and charge carrier dynamics making them highly attractive as\nbuilding blocks for a broad range of photonic devices. For optimal solutions\nconcerning device performance and cost, a crucial element is the selection of a\nsuitable material system which could enable a large wavelength tunability,\nstrong light interaction and simple integration with the mainstream silicon\ntechnologies. The emerging GaBiAs alloys offer such promising features and may\nlead to a new era of technologies. Here, we apply million-atom atomistic\nsimulations to design GaBiAs/GaAs core-shell nanowires suitable for low-loss\ntelecom-wavelength photonic devices. The effects of internal strain, Bi\nComposition (x), random alloy configuration, and core-to-shell diameter ratio\n($\\rm \\rho_D$) are analysed and delineated by systematically varying these\nattributes and studying their impact on the absorption wavelength and charge\ncarrier confinement. The complex interplay between x and $\\rm \\rho_D$ results\nin two distinct pathways to accomplish 1.55 um optical transitions: either\nfabricate nanowires with $\\rm \\rho_D \\geq$ 0.8 and $x \\sim$15\\%, or increase\n$x$ to $\\sim$30\\% with $\\rm \\rho_D \\leq$ 0.4. Upon further analysis of the\nelectron hole wave functions, inhomogeneous broadening and optical transition\nstrengths, the nanowires with $\\rm \\rho_D \\leq$ 0.4 are unveiled to render\nfavourable properties for the design of photonic devices. Another important\noutcome of our study is to demonstrate the possibility of modulating the strain\ncharacter from a compressive to a tensile regime by simply engineering the\nthickness of the core region. The availability of such a straightforward knob\nfor strain manipulation would be highly desirable for devices involving\npolarisation-sensitive light interactions."
    },
    {
        "anchor": "Multi-Channel Transport in Disordered Medium under Generic Scattering\n  Conditions: Our study of the evolution of transmission eigenvalues, due to changes in\nvarious physical parameters in a disordered region of arbitrary dimensions,\nresults in a generalization of the celebrated DMPK equation. The evolution is\nshown to be governed by a single complexity parameter which implies a deep\nlevel of universality of transport phenomena through a wide range of disordered\nregions. We also find that the interaction among eigenvalues is of many body\ntype that has important consequences for the statistical behavior of transport\nproperties.",
        "positive": "Modified valence force field approach for phonon dispersion: from\n  zinc-blende bulk to nanowires: he correct estimation of thermal properties of ultra-scaled CMOS and\nthermoelectric semiconductor devices demands for accurate phonon modeling in\nsuch structures. This work provides a detailed description of the modified\nvalence force field (MVFF) method to obtain the phonon dispersion in\nzinc-blende semiconductors. The model is extended from bulk to nanowires after\nincorporating proper boundary conditions. The computational demands by the\nphonon calculation increase rapidly as the wire cross-section size increases.\nIt is shown that the nanowire phonon spectrum differ considerably from the bulk\ndispersions. This manifests itself in the form of different physical and\nthermal properties in these wires. We believe that this model and approach will\nprove beneficial in the understanding of the lattice dynamics in the next\ngeneration ultra-scaled semiconductor devices."
    },
    {
        "anchor": "On the low-temperature anomalies in the thermal conductivity of\n  plastically deformed crystals due to phonon-kink scattering: Previous experimental studies of the thermal conductivity of plastically\ndeformed lead crystals in the superconducting state have shown strong anomalies\nin the thermal conductivity. Similar effects were also found for the thermal\nconductivity of bent ${}^4\\text{He}$ samples. Until now, a theoretical\nexplanation for these results was missing. In this paper we will introduce the\nprocess of phonon-kink scattering and show that it qualitatively explains the\nanomalies that experiments had found.",
        "positive": "Resonant single and multi-photon coherent transitions in a detuned\n  regime: We performed quantum manipulations of the multi-level spin system S=5/2 of a\nMn$^{2+}$ ion, by means of a two-tone pulse drive. The detuning between the\nexcitation and readout radio frequency pulses allows one to select the number\nof photons involved in a Rabi oscillation as well as increase the frequency of\nthis nutation. Thus detuning can lead to a resonant multi-photon process. Our\nanalytical model for a two-photon process as well as a numerical generalization\nfit well the experimental findings, with implications in the use of multi-level\nspin systems as tunable solid state qubits."
    },
    {
        "anchor": "Topology invisible to eigenvalues in obstructed atomic insulators: We consider the extent to which symmetry eigenvalues reveal the topological\ncharacter of bands. Specifically, we compare distinct atomic limit phases (band\nrepresentations) that share the same irreducible representations (irreps) at\nall points in the Brillouin zone and, therefore, appear equivalent in a\nclassification based on eigenvalues. We derive examples where such\n\"irrep-equivalent\" phases can be distinguished by a quantized Berry phase or\ngeneralization thereof. These examples constitute a generalization of the\nSu-Schrieffer-Heeger chain: neither phase is topological, in the sense that\nlocalized Wannier functions exist, yet there is a topological obstruction\nbetween them. We refer to two phases as \"Berry obstructed atomic limits\" if\nthey have the same irreps, but differ by Berry phases. This is a distinct\nnotion from eigenvalue obstructed atomic limits, which differ in their symmetry\nirreps at some point in the Brillouin zone. We compute exhaustive lists of\nelementary band representations that are irrep-equivalent, in all space groups,\nwith and without time-reversal symmetry and spin-orbit coupling, and use group\ntheory to derive a set of necessary conditions for irrep-equivalence. Finally,\nwe conjecture, and in some cases prove, that irrep-equivalent elementary band\nrepresentations that are not equivalent can be distinguished by a topological\ninvariant.",
        "positive": "Two components of donor-acceptor recombination in compensated\n  semiconductors. Analytical model of spectra in presence of electrostatic\n  fluctuations: We report numerical and analytical studies of the donor-acceptor\nrecombination in compensated semiconductors. Our calculations take into account\nrandom electric fields of charged impurities which are important in non zero\ncompensation case. We show that the donor-acceptor optical spectrum can be\ndescribed as a sum of two components: monomolecular and bimolecular. In the low\ncompensation limit we develop two analytical models for both types of the\nrecombination. Also our numerical simulation predicts that these two components\nof the photoluminescence spectra can be resolved under certain experimental\nconditions."
    },
    {
        "anchor": "Dielectric breakdown by electric-field induced phase separation: The control of the dielectric and conductive properties of device-level\nsystems is important for increasing the efficiency of energy- and\ninformation-related technologies. In some cases, such as neuromorphic\ncomputing, it is desirable to increase the conductivity of an initially\ninsulating medium by several orders of magnitude, resulting in effective\ndielectric breakdown. Here, we show that by tuning the value of the applied\nelectric field in systems { with variable permittivity and electric\nconductivity}, e.g. ion intercalation materials, we can vary the device-level\nelectrical conductivity by orders of magnitude. We attribute this behavior to\nthe formation of filament-like conductive domains that percolate throughout the\nsystem, { which form only when the electric conductivity depends on the\nconcentration}. We conclude by discussing the applicability of our results in\nneuromorphic computing devices and Li-ion batteries.",
        "positive": "Charged basal stacking fault (BSF) scattering in nitride semiconductors: A theory of charge transport in semiconductors in the presence of basal\nstacking faults is developed. It is shown that the presence of basal stacking\nfaults leads to anisotropy in carrier transport. The theory is applied to\ncarrier transport in non-polar GaN films consisting of a large number BSFs, and\nthe result is compared with experimental data."
    },
    {
        "anchor": "SQUID pattern disruption in transition metal dichalcogenide Josephson\n  junctions due to non-parabolic dispersion of the edge states: We theoretically study Josephson junctions with a transition metal\ndichalcogenide zigzag ribbon as a weak link. We demonstrate that the spatial\nprofile of the supercurrent carried by the edge modes determines the critical\ncurrent dependence on the perpendicular magnetic field. We explore this finding\nand analyze the impact of Zeeman interaction and the orbital effects of the\nmagnetic field on the Andreev bound states energies. We show that the unequal\nFermi velocities of the spin-opposite edge modes lead to an anomalous shift of\nthe Andreev bound states in the presence of the magnetic field. This is\nmanifested in a pronounced modification of the SQUID critical current\noscillations when two opposite edges of the ribbon are conducting and can be\nexploited in order to reveal the anomalous phase shift of the Andreev bound\nstates in a single Josephson junction device.",
        "positive": "Local density of states on a vibrational quantum dot out of equilibrium: We calculate the nonequilibrium local density of states on a vibrational\nquantum dot coupled to two electrodes at T=0 using a numerically exact\ndiagrammatic Monte Carlo method. Our focus is on the interplay between the\nelectron-phonon interaction strength and the bias voltage. We find that the\nspectral density exhibits a significant voltage dependence if the voltage\nwindow includes one or more phonon sidebands. A comparison with\nwell-established approximate approaches indicates that this effect could be\nattributed to the nonequilibrium distribution of the phonons. Moreover, we\ndiscuss the long transient dynamics caused by the electron-phonon coupling."
    },
    {
        "anchor": "Signatures of the Current Blockade Instability in Suspended Carbon\n  Nanotubes: Transport measurements allow sensitive detection of nanomechanical motion of\nsuspended carbon nanotubes. It has been predicted that when the\nelectro-mechanical coupling is sufficiently large a bistability with a current\nblockade appears. Unambiguous observation of this transition by current\nmeasurements may be difficult. Instead, we investigate the mechanical response\nof the system, namely the displacement spectral function; the linear response\nto a driving; and the ring-down behavior. We find that by increasing the\nelectro-mechanical coupling the peak in the spectral function broadens and\nshifts at low frequencies while the oscillator dephasing time shortens. These\neffects are maximum at the transition where non-linearities dominate the\ndynamics. These strong signatures open the way to detect the blockade\ntransition in devices currently studied by several groups.",
        "positive": "Electronic states of disordered grain boundaries in graphene prepared by\n  chemical vapor deposition: Perturbations of the two dimensional carbon lattice of graphene, such as\ngrain boundaries, have significant influence on the charge transport and\nmechanical properties of this material. Scanning tunneling microscopy\nmeasurements presented here show that localized states near the Dirac point\ndominate the local density of states of grain boundaries in graphene grown by\nchemical vapor deposition. Such low energy states are not reproduced by\ntheoretical models which treat the grain boundaries as periodic\ndislocation-cores composed of pentagonal-heptagonal carbon rings. Using ab\ninitio calculations, we have extended this model to include disorder, by\nintroducing vacancies into a grain boundary consisting of periodic\ndislocation-cores. Within the framework of this model we were able to reproduce\nthe measured density of states features. We present evidence that grain\nboundaries in graphene grown on copper incorporate a significant amount of\ndisorder in the form of two-coordinated carbon atoms."
    },
    {
        "anchor": "Nonequilibrium spin-boson model: from weak to strong coupling: We present a general theory to explore energy transfer in nonequilibrium\nspin-boson models within the framework of nonequilibrium Green's function\n(NEGF). In contrast to conventionally used NEGF methods based on a perturbation\nexpansion in the system-bath coupling, we adopt the polaron transformation to\nthe Hamiltonian and identify the tunneling term as a perturbation with the\nsystem-bath coupling being treated nonperturbatively, herein termed the\npolaron-transformed NEGF method. To evaluate terms in the Dyson series, we\nfurther utilize the Majorana-fermion representation. The proposed method not\nonly allows us to deal with weak as well as strong coupling regime, but also\nenables an investigation on the role of bias. As an application of the method,\nwe study the energy transfer between two Ohmic bosonic baths mediated by a\nspin. For a unbiased spin system, our energy current result smoothly bridges\npredictions of two benchmarks, namely, the quantum master equation and the\nnonequilibrium non-interacting blip approximation, thus our method is beyond\nexisting theories. In case of a biased spin system, we reveal a bias-induced\nnonmomotonic behavior of the energy conductance in the intermediate coupling\nregime, due to the resonant character of the energy transfer. This finding may\noffer a nontrivial quantum control knob over energy transfer at the nanoscale.",
        "positive": "Room-temperature Single Photon Emitters in Cubic Boron Nitride\n  Nanocrystals: Color centers in wide bandgap semiconductors are attracting broad attention\nas platforms for quantum technologies relying on room-temperature single-photon\nemission (SPE), and for nanoscale metrology applications building on the\ncenters' response to electric and magnetic fields. Here, we demonstrate\nroom-temperature SPE from defects in cubic boron nitride (cBN) nanocrystals,\nwhich we unambiguously assign to the cubic phase using spectrally resolved\nRaman imaging. These isolated spots show photoluminescence (PL) spectra with\nzero-phonon lines (ZPLs) within the visible region (496-700 nm) when subject to\nsub-bandgap laser excitation. Second-order autocorrelation of the emitted\nphotons reveals antibunching with $g^{2}$ ~ 0.2 and a decay constant of 2.75 ns\nthat is further confirmed through fluorescence lifetime measurements. The\nresults presented herein prove the existence of optically addressable isolated\nquantum emitters originating from defects in cBN, making this material an\ninteresting platform for opto-electronic devices and quantum applications."
    },
    {
        "anchor": "Pairing instabilities of Dirac composite fermions: Recently, a Dirac (particle-hole symmetric) description of composite fermions\nin the half-filled quantum Hall system was proposed [D. T. Son, Phys. Rev. X 5,\n031027 (2015)], and we study its possible consequences on BCS (Cooper) pairing\nof composite fermions (CF's). One of the main consequences is the existence of\nanisotropic states in single and bilayer systems, which was previously\nsuggested in Ref. [J. S. Jeong and K. Park, Phys. Rev. B 91, 195119 (2015)]. We\nargue that in the half-filled single layer the gapped states may sustain\nanisotropy, because isotropic pairings may coexist with anisotropic ones.\nFurthermore, anisotropic pairings with addition of a particle-hole (PH)\nsymmetry breaking mass term may evolve into rotationally symmetric states, i.e.\nPfaffian states of Halperin-Lee-Read (HLR) ordinary CF's. On the basis of the\nDirac formalism, we argue that in the quantum Hall bilayer at total filling\none, with decreasing distance between layers weak pairing of p-wave paired CF's\nis gradually transformed from Dirac to ordinary, HLR-like, with concomitant\ndecrease in the CF number. Global characterization of low-energy spectrum based\non the Dirac CF's agrees well with previous calculations performed by exact\ndiagonalization on a torus. Finally, we discuss features of Dirac formalism\nwhen applied in this context.",
        "positive": "Incommensurate ground state of double-layer quantum Hall systems: Double-layer quantum Hall systems possess interlayer phase coherence at\nsufficiently small layer separations, even without interlayer tunneling. When\ninterlayer tunneling is present, application of a sufficiently strong in-plane\nmagnetic field $B_\\parallel > B_c$ drives a commensurate-incommensurate (CI)\ntransition to an incommensurate soliton-lattice (SL) state. We calculate the\nHartree-Fock ground-state energy of the SL state for all values of\n$B_\\parallel$ within a gradient approximation, and use it to obtain the\nanisotropic SL stiffness, the Kosterlitz-Thouless melting temperature for the\nSL, and the SL magnetization. The in-plane differential magnetic susceptibility\ndiverges as $(B_\\parallel - B_c)^{-1}$ when the CI transition is approached\nfrom the SL state."
    },
    {
        "anchor": "Fine-structure splitting of exciton states in quantum dot molecules:\n  symmetry and tunnel-coupling effects: Exciton levels and fine-structure splitting in laterally-coupled quantum dot\nmolecules are studied. The electron and hole tunneling energies as well as the\ndirect Coulomb interaction are essential for the exciton levels. It is found\nthat fine-structure splitting of the two-lowest exciton levels is contributed\nfrom the intra- and inter-dot exchange interactions, both of which are largely\ninfluenced by the symmetry and tunnel-coupling between the two dots. As the\ninter-dot separation is reduced, fine-structure splitting of the exciton ground\nstate is largely increased while those of the excited states are decreased.\nMoreover, the dependence of the fine-structure splitting in quantum dot\nmolecules on the Coulomb correlation is clearly clarified.",
        "positive": "Charged excitons or trions in 2D parabolic quantum dots?: So far in the literature the terms \"charged exciton\" and \"trion\" are often\nconfused with each other and mostly considered as the same. In this work we\nshow this is not the case in 2D quantum dots with a parabolic confinement. By\nusing the unrestricted Hartree-Fock method the energy and binding energy of\nboth charged excitons and trions in 2D parabolic quantum dots are calculated in\ndependence on the confinements of charge carriers in quantum dot. It is shown\nthat the binding energies of the charged exciton and the trion behave\ndifferently in regard to the ratios of the confinements between the electron\nand hole. The effect of the external magnetic field on the binding energies of\ncharged excitons has been also considered."
    },
    {
        "anchor": "Spin Hall effect in a two-dimensional electron gas in the presence of a\n  magnetic field: We study the spin Hall effect of a two-dimensional electron gas in the\npresence of a magnetic field and both the Rashba and Dresselhaus spin-orbit\ninteractions. We show that the value of the spin Hall conductivity, which is\nfinite only if the Zeeman spin splitting is taken into account, may be tuned by\nvarying the ratio of the in-plane and out-of-plane components of the applied\nmagnetic field. We identify the origin of this behavior with the different role\nplayed by the interplay of spin-orbit and Zeeman couplings for in-plane and\nout-of-plane magnetic field components.",
        "positive": "Quantized Fermi-arc-mediated transport in Weyl semimetal nanowires: We study longitudinal transport in Weyl semimetal nanowires, both in the\nabsence and in the presence of a magnetic flux threading the nanowires. We\nidentify two qualitatively different regimes of transport with respect to the\nchemical potential in the nanowires. In the \"surface regime\", for low doping,\nmost of the conductance occurs through the Fermi-arc surface states, and it\nrises in steps of one quantum of conductance as a function of the chemical\npotential; furthermore, with varying flux the conductance changes in steps of\none quantum of conductance with characteristic Fabry-P\\'erot interference\noscillations. In the \"bulk-surface regime\", for highly-doped samples, the\ndominant contribution to the conductance is quadratic in the chemical\npotential, and mostly conditioned by the bulk states; the flux dependence shows\nclearly that both the surface and the bulk states contribute. The two\naforementioned regimes prove that the contribution of the Fermi-arc surface\nstates is salient and, therefore, crucial for understanding transport\nproperties of finite-size Weyl semimetal systems. Last but not least, we\ndemonstrate that both regimes are robust to disorder."
    },
    {
        "anchor": "Bloch oscillations in the magnetoconductance of twisted bilayer graphene: We identify a mapping between two-dimensional (2D) electron transport in a\nminimally twisted graphene bilayer and a 1D quantum walk, where one spatial\ndimension plays the role of time. In this mapping a magnetic field B\nperpendicular to the bilayer maps onto an electric field. Bloch oscillations\ndue to the periodic motion in a 1D Bloch band can then be observed in purely DC\ntransport as magnetoconductance oscillations with periodicity set by the Bloch\nfrequency.",
        "positive": "Room And Cryogenic Temperature Behaviour of Magnetic Sensors Based on\n  Gan/Si Single Saw Resonators: This work analyzes resonance frequency shift vs. the applied magnetic field\nstrength for GHz operating GaN/Si SAW single resonators. Magnetostrictive\nelements (Ni and CoFeB) were deposited in the proximity of the interdigitated\ntransducers (IDTs) of the resonators (A-type structures) and also over the\nIDTs, after covering them with a BCB layer to avoid short circuits with IDTs\nmetal (B-type structures). This work targets emerging applications of SAW\nresonators in driving spin wave pumping and in coupling of surface acoustic\nwaves (SAW) with superconducting Q-bits. Magnetic sensitivity of the SAWs was\nanalyzed at room temperature (RT) and at cryogenic temperatures, obtaining high\nmagnetic sensitivities at 16 K. According to our knowledge, GaN based SAWs are\nfirst time used in magnetic applications; also, cryogenic behavior of magnetic\nSAW sensors is first time analyzed."
    },
    {
        "anchor": "A $C^\\ast$-algebraic view on the interaction of real- and reciprocal\n  space topology in skyrmion crystals: Understanding the interaction of real- and reciprocal space topology in\nskyrmion crystals is an open problem. We approach it from the viewpoint of\n$C^\\ast$-algebras and calculate all admissible Chern numbers of a strongly\ncoupled tight-binding skyrmion system on a triangular lattice as a function of\nFermi energy and texture parameters. Our analysis reveals the topological\ncomplexity of electronic states coupled to spin textures, and the failure of\nthe adiabatic picture to account for it in terms of emergent electromagnetism.\nOn the contrary, we explain the discontinuous jumps in the real-space winding\nnumber in terms of collective evolution in real-, reciprocal, and mixed space\nChern numbers. Our work sets the stage for further research on topological\ndynamics in complex dynamic spin textures coupled to external fields.",
        "positive": "Modeling temperature-dependent population dynamics in the excited state\n  of the nitrogen-vacancy center in diamond: The nitrogen-vacancy (NV) center in diamond is well known in quantum\nmetrology and quantum information for its favorable spin and optical\nproperties, which span a wide temperature range from near zero to over 600 K.\nDespite its prominence, the NV center's photo-physics is incompletely\nunderstood, especially at intermediate temperatures between 10-100 K where\nphonons become activated. In this work, we present a rate model able to\ndescribe the cross-over from the low-temperature to the high-temperature\nregime. Key to the model is a phonon-driven hopping between the two orbital\nbranches in the excited state (ES), which accelerates spin relaxation via an\ninterplay with the ES spin precession. We extend our model to include magnetic\nand electric fields as well as crystal strain, allowing us to simulate the\npopulation dynamics over a wide range of experimental conditions. Our model\nrecovers existing descriptions for the low- and high-temperature limits, and\nsuccessfully explains various sets of literature data. Further, the model\nallows us to predict experimental observables, in particular the\nphotoluminescence (PL) emission rate, spin contrast, and spin initialization\nfidelity relevant for quantum applications. Lastly, our model allows probing\nthe electron-phonon interaction of the NV center and reveals a gap between the\ncurrent understanding and recent experimental findings."
    },
    {
        "anchor": "Topological frustration of artificial spin ice: Frustrated systems, typically characterized by competing interactions that\ncannot all be simultaneously satisfied, display rich behaviours not found\nelsewhere in nature. Artificial spin ice takes a materials-by-design approach\nto studying frustration, where lithographically patterned bar magnets mimic the\nfrustrated interactions in real materials but are also amenable to direct\ncharacterization. Here, we introduce controlled topological defects into square\nartificial spin ice lattices in the form of lattice edge dislocations and\ndirectly observe the resulting spin configurations. We find the presence of a\ntopological defect produces extended frustration within the system caused by a\ndomain wall with indeterminate configuration. Away from the dislocation, the\nmagnets are locally unfrustrated, but frustration of the lattice persists due\nto its topology. Our results demonstrate the non-trivial nature of topological\ndefects in a new context, with implications for many real systems in which a\ntypical density of dislocations could fully frustrate a canonically\nunfrustrated system.",
        "positive": "Far-field emission profiles from L3 photonic crystal cavity modes: We experimentally characterize the spatial far-field emission profiles for\nthe two lowest confined modes of a photonic crystal cavity of the L3 type,\nfinding a good agreement with FDTD simulations. We then link the far-field\nprofiles to relevant features of the cavity mode near-fields, using a simple\nFabry-Perot resonator model. The effect of disorder on far-field cavity\nprofiles is clarified through comparison between experiments and simulations.\nThese results can be useful for emission engineering from active centers\nembedded in the cavity."
    },
    {
        "anchor": "A Waveguide-Coupled On-Chip Single Photon Source: We investigate single photon generation from individual self-assembled InGaAs\nquantum dots coupled to the guided optical mode of a GaAs photonic crystal\nwaveguide. By performing confocal microscopy measurements on single dots\npositioned within the waveguide, we locate their positions with a precision\nbetter than 0.5 \\mum. Time-resolved photoluminescence and photon\nautocorrelation measurements are used to prove the single photon character of\nthe emission into the propagating waveguide mode. The results obtained\ndemonstrate that such nanostructures can be used to realize an on-chip, highly\ndirected single photon source with single mode spontaneous emision coupling\nefficiencies in excess of beta~85 % and the potential to reach maximum emission\nrates >1 GHz.",
        "positive": "Observation of Unpinned Two-Dimensional Dirac States in Antimony Single\n  Layers with Phosphorene Structure: The discovery of graphene has stimulated enormous interest in two-dimensional\n(2D) electron gas with linear band structure. 2D Dirac materials possess many\nintriguing physical properties such as high carrier mobility and zero-energy\nLandau level thanks to the relativistic dispersion and chiral spin/pseudospin\ntexture. 2D Dirac states discovered so far are exclusively pinned at\nhigh-symmetry points of the Brillouin zone, for example, surface Dirac states\nat $\\overline{\\Gamma}$ in topological insulators Bi$_2$Se(Te)$_3$ and Dirac\ncones at $K$ and $K'$ in graphene. In this work, we report the realization of\n2D Dirac states at generic $k$-points in antimony atomic layers with\nphosphorene structure ($i.e.$ $\\alpha$-antimonene). The unpinned nature enables\nversatile ways to control the locations of the Dirac points in momentum space.\nIn addition, dispersions around the unpinned Dirac points exhibit intrinsically\nanisotropic behaviors due to the reduced symmetry of generic momentum points.\nThese properties make the $\\alpha$-antimonene films a promising platform for\nexploring interesting physics in unpinned 2D Dirac fermions that are distinct\nfrom the conventional Dirac states in graphene."
    },
    {
        "anchor": "Anisotropic Stark shift, field-induced dissociation, and\n  electroabsorption of excitons in phosphorene: We compute binding energies, Stark shifts, electric-field-induced\ndissociation rates, and the Franz-Keldysh effect for excitons in phosphorene in\nvarious dielectric surroundings. All three effects show a pronounced dependence\non the direction of the in-plane electric field, with the dissociation rates in\nparticular decreasing by several orders of magnitude upon rotating the electric\nfield from the armchair to the zigzag axis. To better understand the numerical\ndissociation rates, we derive an analytical approximation to the anisotropic\nrates induced by weak electric fields, thereby generalizing the previously\nobtained result for isotropic two-dimensional semiconductors. This\napproximation is shown to be valid in the weak-field limit by comparing it to\nthe exact rates. The anisotropy is also apparent in the large difference\nbetween armchair and zigzag components of the exciton polarizability tensor,\nwhich we compute for the five lowest lying states. As expected, we also find\nmuch more pronounced Stark shifts in either the armchair or zigzag direction,\ndepending on the symmetry of the state in question. Finally, an isotropic\ninteraction potential is shown to be an excellent approximation to a more\naccurate anisotropic interaction derived from the Poisson equation, confirming\nthat the anisotropy of phosphorene is largely due to the direction dependence\nof the effective masses.",
        "positive": "Vortex Lattices in Rotating Atomic Bose Gases with Dipolar Interactions: We show that dipolar interactions have dramatic effects on the groundstates\nof rotating atomic Bose gases in the weak interaction limit. With increasing\ndipolar interaction (relative to the net contact interaction), the mean-field,\nor high filling fraction, groundstate undergoes a series of transitions between\nvortex lattices of different symmetries: triangular, square, ``stripe'', and\n``bubble'' phases. We also study the effects of dipolar interactions on the\nquantum fluids at low filling fractions. We show that the incompressible\nLaughlin state at filling fraction $\\nu=1/2$ is replaced by compressible stripe\nand bubble phases."
    },
    {
        "anchor": "Magnetotransport effects of ultrathin Ni80Fe20 films probed in-situ: We have investigated the magnetoresistance of Permalloy (Ni80Fe20) films with\nthicknesses ranging from a single monolayer to 12 nm, grown on Al2O3, MgO and\nSiO2 substrates. Growth and transport measurements were carried out under\ncryogenic conditions in UHV. Applying in-plane magnetic vector fields up to 100\nmT, the magnetotransport properties are ascertained during growth. With\nincreasing thickness the films exhibit a gradual transition from tunneling\nmagnetoresistance to anisotropic magnetoresistance. This corresponds to the\nevolution of the film structure from separated small islands to a network of\ninterconnected grains as well as the transition from superparamagnetic to\nferromagnetic behavior of the film. Using an analysis based on a theoretical\nmodel of the island growth, we find that the observed evolution of the\nmagnetoresistance in the tunneling regime originates from the changes in the\nisland size distribution during growth. Depending on the substrate material,\nsignificant differences in the magnetoresistance response in the transition\nregime between tunneling magnetoresistance and anisotropic magnetoresistance\nwere found. We attribute this to an increasingly pronounced island growth and\nslower percolation process of Permalloy when comparing growth on SiO2, MgO and\nAl2O3 substrates. The different growth characteristics result in a markedly\nearlier onset of both tunneling magnetoresistance and anisotropic\nmagnetoresistance for SiO2. For Al2O3 in particular the growth mode results in\na structure of the film containing two different contributions to the\nferromagnetism which lead to two distinct coercive fields in the high thickness\nregime.",
        "positive": "Spin Field Effect Transistors with Ultracold Atoms: We propose a method of constructing cold atom analogs of the spintronic\ndevice known as the Datta-Das transistor (DDT), which despite its seminal\nconceptual role in spintronics, has never been successfully realized with\nelectrons. We propose two alternative schemes for an atomic DDT, both of which\nare based on the experimental setup for tripod stimulated Raman adiabatic\npassage. Both setups involve atomic beams incident on a series of laser fields\nmimicking the relativistic spin orbit coupling for electrons that is the\noperating mechanism of the DDT."
    },
    {
        "anchor": "A versatile simulator for specular reflectivity study of multi-layer\n  thin films: A versatile X-ray/neutron reflectivity (specular) simulator using\nLabVIEW(National Instruments Corp.) for structural study of a multi-layer thin\nfilm having any combination, including the repetitions, of nano-scale layers of\ndifferent materials is presented here (available to download from the link\nprovided at the end of the paper). Inclusion of absorption of individual\nlayers, inter-layer roughnesses, background counts, beam width, instrumental\nresolution and footprint effect due to finite size of the sample makes the\nsimulated reflectivity close to practical one. The effect of multiple\nreflection is compared with simulated curves following the exact dynamical\ntheory and approximated kinematical theory. The applicability of further\napproximation (Born theory) that the incident angle does not change\nsignificantly from one layer to another due to refraction is also considered.\nBrief discussion about reflection from liquid surface/interface and\nreflectivity study using polarized neutron are also included as a part of the\nreview. Auto-correlation function in connection with the data inversion\ntechnique is discussed with possible artifacts for phase-loss problem. An\nexperimental specular reflectivity data of multi-layer erbium stearate\nLangmuir-Blodgett (LB) film is considered to estimate the parameters by\nsimulating the reflectivity curve.",
        "positive": "Coherent transport through a Majorana island in an Aharonov-Bohm\n  interferometer: Majorana zero modes are leading candidates for topological quantum\ncomputation due to non-local qubit encoding and non-abelian exchange\nstatistics. Spatially separated Majorana modes are expected to allow\nphase-coherent single-electron transport through a topological superconducting\nisland via a mechanism referred to as teleportation. Here we experimentally\ninvestigate such a system by patterning an elongated epitaxial InAs-Al island\nembedded in an Aharonov-Bohm interferometer. With increasing parallel magnetic\nfield, a discrete sub-gap state in the island is lowered to zero energy\nyielding persistent 1e-periodic Coulomb blockade conductance peaks (e is the\nelementary charge). In this condition, conductance through the interferometer\nis observed to oscillate in a perpendicular magnetic field with a flux period\nof h/e (h is Planck's constant), indicating coherent transport of single\nelectrons through the islands, a signature of electron teleportation via\nMajorana modes, could also be observed, suggesting additional non-Majorana\nmechanisms for 1e transport through these moderately short wires."
    },
    {
        "anchor": "On the Cooling of Electrons in a Silicon Inversion Layer: The cooling of two-dimensional electrons in silicon-metal-oxide semiconductor\nfield effect transistors is studied experimentally. Cooling to the lattice is\nfound to be more effective than expected from the bulk electron-phonon coupling\nin silicon. Unexpectedly, the extracted heat transfer rate to phonons at low\ntemperatures depends cubically on electron temperature, suggesting that\npiezoelectric coupling (absent in bulk silicon) dominates over deformation\npotential. According to our findings, at 100 mK, electrons farther than 0.1 mm\nfrom the contacts are mostly cooled by phonons. Using long devices and low\nexcitation voltage we measure electron resistivity down to 100 mK and find that\nsome of the \"metallic\" curves, reported earlier, turn insulating below about\n300 mK. This finding renders the definition of the claimed 2D metal-insulator\ntransition questionable. Previous low temperature measurements in silicon\ndevices are analyzed and thumb rules for evaluating their electron temperatures\nare provided.",
        "positive": "Single Flux Transistor: the controllable interplay of Coherent Quantum\n  Phase Slip and Flux quantization: The Single Cooper Pair Josephson Transistor is a device that exhibits at the\nsame time charge quantization and phase coherence. Coherent quantum phase slip\nphenomenon is \"dual\" the Josephson phase coherence while the charge\nquantization is dual to the flux quantization. We present the experimental\ndemonstration and the theoretical description of a new superconducting device -\nSingle Flux Transistor, which is dual to the Single Cooper Pair Transistor. Our\ntransport measurements show the periodic modulation of the critical voltage by\nthe external magnetic field. The obtained current-voltage characteristics show\nthe hysteretic behavior, which we attribute to the intrinsic self-heating of\ncharge carriers."
    },
    {
        "anchor": "Berry-phase effects and electronic dynamics in noncollinear\n  antiferromagnetic texture: Antiferromagnets (AFMs), in contrast to ferromagnets, show a nontrivial\nmagnetic structure with zero net magnetization. However, they share a number of\nspintronic effects with ferromagnets, including spin-pumping and spin transfer\ntorques. Both phenomena stem from the coupled dynamics of free carriers and\nlocalized magnetic moments. In the present paper I study the adiabatic dynamics\nof a spin-polarized electrons in a metallic AFM exhibiting a noncollinear\n120$^\\circ$ magnetic structure. I show that the slowly varying AFM spin texture\nproduces a non-Abelian gauge potential related to the time/space gradients of\nthe N\\'{e}el vectors. Corresponding emergent electric and magnetic fields\ninduce rotation of spin and influence the orbital dynamics of free electrons. I\ndiscuss both the possibility of a topological spin Hall effect in the vicinity\nof topological AFM solitons with nonzero curvature and rotation of the electron\nspin traveling through the AFM domain wall.",
        "positive": "Circuit Quantum Electrodynamics: Coherent Coupling of a Single Photon to\n  a Cooper Pair Box: Under appropriate conditions, superconducting electronic circuits behave\nquantum mechanically, with properties that can be designed and controlled at\nwill. We have realized an experiment in which a superconducting two-level\nsystem, playing the role of an artificial atom, is strongly coupled to a single\nphoton stored in an on-chip cavity. We show that the atom-photon coupling in\nthis circuit can be made strong enough for coherent effects to dominate over\ndissipation, even in a solid state environment. This new regime of matter light\ninteraction in a circuit can be exploited for quantum information processing\nand quantum communication. It may also lead to new approaches for single photon\ngeneration and detection."
    },
    {
        "anchor": "Dirac fermion time-Floquet crystal: manipulating Dirac points: We demonstrate how to control the spectra and current flow of Dirac electrons\nin both a graphene sheet and a topological insulator by applying either two\nlinearly polarized laser fields with frequencies $\\omega$ and $2\\omega$ or a\nmonochromatic (one-frequency) laser field together with a spatially periodic\nstatic potential(graphene/TI superlattice). Using the Floquet theory and the\nresonance approximation, we show that a Dirac point in the electron spectrum\ncan be split into several Dirac points whose relative location in momentum\nspace can be efficiently manipulated by changing the characteristics of the\nlaser fields. In addition, the laser-field controlled Dirac fermion band\nstructure -- Dirac fermion time-Floquet crystal -- allows the manipulation of\nthe electron currents in graphene and topological insulators. Furthermore, the\ngeneration of dc currents of desirable intensity in a chosen direction occurs\nwhen applying the bi-harmonic laser field which can provide a straightforward\nexperimental test of the predicted phenomena.",
        "positive": "Electron and hole Hong-Ou-Mandel interferometry: We consider the electronic analog of the quantum optics Hong-Ou-Mandel\ninterferometer, in a realistic condensed matter device based on single electron\nemission in chiral edge states. For electron-electron collisions, we show that\nthe measurement of the zero-frequency current correlations at the output of a\nquantum point contact produces a dip giving precious information on the\nelectronic wavepackets and coherence. As a feature truly unique to Fermi\nstatistics and condensed matter, we show that two-particle interferences\nbetween electron and hole in the Fermi sea can produce a positive peak in the\ncurrent correlations, which we study for realistic experimental parameters."
    },
    {
        "anchor": "Multi-terminal magneto-transport in an interacting fractal network: a\n  mean field study: Magneto-transport of interacting electrons in a Sierpinski gasket fractal is\nstudied within a mean field approach. We work out the three-terminal transport\nand study the interplay of the magnetic flux threading the planar gasket and\nthe dephasing effect introduced by the third lead. For completeness we also\nprovide results of the two-terminal transport in presence of electron-electron\ninteraction. It is observed that dephasing definitely reduces the transport,\nwhile the magnetic field generates a continuum in the transmission spectrum\nsignaling a band of extended eigenstates in this non-translationally invariant\nfractal structure. The Hubbard interaction and the dephasing introduced by the\nthird lead play their parts in reducing the average transmission, and opens up\ngaps in the spectrum, but can not destroy the continuum in the spectrum.",
        "positive": "Efficient stopping of current-driven domain wall using a local Rashba\n  field: We theoretically show that a locally-embedded Rashba interaction acts as a\nstrong pinning center for current-driven domain walls and demonstrate efficient\ncapturing and depinning of the wall using a weak Rashba interaction of the\norder of 0.01 eV{\\AA}. Our discovery is expected to be useful for the highly\nreliable control of domain walls in racetrack memories."
    },
    {
        "anchor": "Ultrafast pseudospin dynamics in graphene: Interband optical transitions in graphene are subject to pseudospin selection\nrules. Impulsive excitation with linearly polarized light generates an\nanisotropic photocarrier occupation in momentum space that evolves at\ntimescales shorter than 100fs. Here, we investigate the evolution of\nnon-equilibrium charges towards an isotropic distribution by means of\nfluence-dependent ultrafast spectroscopy and develop an analytical model able\nto quantify the isotropization process. In contrast to conventional\nsemiconductors, the isotropization is governed by optical phonon emission,\nrather than electron-electron scattering, which nevertheless contributes in\nshaping the anisotropic photocarrier occupation within the first few fs.",
        "positive": "Microscopic origin of the effective spin-spin interaction in a\n  semiconductor quantum dot ensemble: We present a microscopic model for a singly charged quantum dot (QD) ensemble\nto reveal the origin of the long-range effective interaction between the\nelectron spins in the QDs. Wilson's numerical renormalization group (NRG) is\nused to calculate the magnitude and the spatial dependency of the effective\nspin-spin interaction mediated by the growth induced wetting layer.\nSurprisingly, we found an antiferromagnetic Heisenberg coupling for very short\ninter-QD distances that is caused by the significant particle-hole asymmetry of\nthe wetting layer band at very low filling. Using the NRG results obtained from\nrealistic parameters as input for a semiclassical simulation for a large QD\nensemble, we demonstrate that the experimentally reported phase shifts in the\ncoherent spin dynamics between single and two color laser pumping can be\nreproduced by our model, solving a longstanding mystery of the microscopic\norigin of the inter QD electron spin-spin interaction."
    },
    {
        "anchor": "Electrons and polarons at oxide interfaces explored by soft-X-ray ARPES: Soft-X-ray ARPES (SX-ARPES) with its enhanced probing depth and chemical\nspecificity allows access to fundamental electronic structure characteristics -\nmomentum-resolved spectral function, band structure, Fermi surface - of systems\ndifficult and even impossible for the conventional ARPES such as\nthree-dimensional materials, buried interfaces and impurities. After a recap of\nthe spectroscopic abilities of SX-ARPES, we review its applications to oxide\ninterfaces, focusing on the paradigm LaAlO3-SrTiO3 interface. Resonant SX-ARPES\nat the Ti L-edge accentuates photoemission response of the mobile interface\nelectrons and exposes their dxy-, dyz- and dxz-derived subbands forming the\nFermi surface in the interface quantum well. After a recap of the\nelectron-phonon interaction physics, we demonstrate that peak-dip-hump\nstructure of the experimental spectral function manifests the Holstein-type\nlarge polaron nature of the interface charge carriers, explaining their\nfundamentally reduced mobility. Coupling of the charge carriers to polar soft\nphonon modes defines dramatic drop of mobility with temperature. Oxygen\ndeficiency adds another dimension to the rich physics of LaAlO3-SrTiO3\nresulting from co-existence of mobile and localized electrons introduced by\noxygen vacancies. Oxygen deficiency allows tuning of the polaronic coupling and\nthus mobility of the charge carriers, as well as of interfacial ferromagnetism\nconnected with various atomic configurations of the vacancies. Finally, we\ndiscuss spectroscopic evidence of phase separation at the LaAlO3-SrTiO3\ninterface. Concluding, we put prospects of SX-ARPES for complex\nheterostructures, spin-resolving experiments opening the totally unexplored\nfield of interfacial spin structure, and in-operando field-effect experiments\npaving the way towards device applications of the reach physics of oxide\ninterfaces.",
        "positive": "Negative differential transmission in graphene: By using the Kubo linear response theory with the Keldysh Green function\napproach, we investigate the mechanism leading to the negative differential\ntransmission in system with the equilibrium electron density much smaller than\nthe photon-excited one. It is shown that the negative differential transmission\ncan appear at low probe-photon energy (in the order of the scattering rate) or\nat high energy (much larger than the scattering rate). For the low probe-photon\nenergy case, the negative differential transmission is found to come from the\nincrease of the intra-band conductivity due to the large variation of electron\ndistribution after the pumping. As for the high probe-photon energy case, the\nnegative differential transmission is shown to tend to appear with the\nhot-electron temperature being closer to the equilibrium one and the chemical\npotential higher than the equilibrium one but considerably smaller than half of\nthe probe-photon energy. We also show that this negative differential\ntransmission can come from both the inter- and the intra-band components of the\nconductivity. Especially, for the inter-band component, its contribution to the\nnegative differential transmission is shown to come from both the Hartree-Fock\nself-energy and the scattering. Furthermore, the influence of the Coulomb-hole\nself-energy is also addressed."
    },
    {
        "anchor": "Coulomb screening and collective excitations in biased bilayer graphene: We have investigated the Coulomb screening properties and plasmon spectrum in\na bilayer graphene under a perpendicular electric bias. The bias voltage\napplied between the two graphene layers opens a gap in the single particle\nenergy spectrum and modifies the many-body correlations and collective\nexcitations. The energy gap can soften the plasmon modes and lead to a\ncrossover of the plasmons from a Landau damped mode to being undamped. Plasmon\nmodes of long lifetime may be observable in experiments and may have potentials\nfor device applications.",
        "positive": "Shot noise in Weyl semimetals: We study the effect of inelastic processes on the magneto-transport of a\nquasi-one dimensional Weyl semi-metal, using a modified Boltzmann-Langevin\napproach. The magnetic field drives a crossover to a ballistic regime in which\nthe propagation along the wire is dominated by the chiral anomaly, and the role\nof fluctuations inside the sample is exponentially suppressed. We show that\ninelastic collisions modify the parametric dependence of the current\nfluctuations on the magnetic field. By measuring shot noise as a function of a\nmagnetic field, for different applied voltage, one can estimate the\nelectron-electron inelastic length $l_{\\rm ee}$."
    },
    {
        "anchor": "Paired electron motion in interacting chains of quantum dots: We study the motion of a pair of electrons along two separate parallel chains\nof quantum dots. The electrons that are released from the central dot of each\nchain tend to accompany and not avoid each other. The correlated electron\nmotion involves entanglement of the wave functions which is generated in time\nupon release of the initial confinement. Observation of the simultaneous\npresence of electrons at the same side of the chain can provide fingerprint of\nthe paired electron motion.",
        "positive": "Theory of giant skew scattering by spin cluster: Skew scattering of electrons induced by a spin cluster is studied\ntheoretically focusing on metals with localized magnetic moments. The\nscattering probability is calculated by a non-perturbative $T$ matrix method;\nthis method is valid for arbitrary strength of electron-spin coupling. We show\nthe scattering of electrons by a three-spin cluster produces a skew angle of\norder $0.1\\pi$ rad when the electron-spin coupling is comparable to the\nbandwidth. This is one or two orders of magnitude larger than the usual skew\nangle by an impurity with spin-orbit interaction. Systematic analysis of the\nscattering probability of one-, two-, and three-spin clusters show that three\nspins are necessary for skew scattering. We also discuss the relation between\nanomalous/spin Hall effects and the spin chiralities; we find that the spin\nHall effect requires three spins while it is related to the vector spin\nchirality defined by a pair of spins. The relevance of these results to the\nlarge extrinsic anomalous and spin Hall effects in noncentrosymmetric and/or\nfrustrated magnets is also discussed."
    },
    {
        "anchor": "Decoherence of flux qubits due to 1/f flux noise: We have investigated decoherence in Josephson-junction flux qubits. Based on\nthe measurements of decoherence at various bias conditions, we discriminate\ncontributions of different noise sources. In particular, we present a Gaussian\ndecay function of the echo signal as evidence of dephasing due to $1/f$ flux\nnoise whose spectral density is evaluated to be about $(10^{-6} \\Phi_0)^2$/Hz\nat 1 Hz. We also demonstrate that at an optimal bias condition where the noise\nsources are well decoupled the coherence observed in the echo measurement is\nmainly limited by energy relaxation of the qubit.",
        "positive": "The influence of adatom diffusion on the formation of skyrmion lattice\n  in sub-monolayer Fe on Ir(111): Room temperature grown Fe monolayer (ML) on the Ir(111) single crystal\nsubstrate has attracted great research interests as nano-skyrmion lattice can\nform under proper growth conditions. The formation of the nanoscale skyrmion,\nhowever, appears to be greatly affected by the diffusion length of the Fe\nadatoms on the Ir(111) surface. We made this observation by employing\nspin-polarized scanning tunneling microscopy to study skyrmion formation upon\nsystematically changing the impurity density on the substrate surface prior to\nFe deposition. Since the substrate surface impurities serve as pinning centers\nfor Fe adatoms, the eventual size and shape of the Fe islands exhibit a direct\ncorrelation with the impurity density, which in turn determines whether\nskyrmion can be formed. Our observation indicates that skyrmion only forms when\nthe impurity density is below 0.006/nm2, i.e., 12 nm averaged spacing between\nthe neighboring defects. We verify the significance of Fe diffusion length by\ngrowing Fe on clean Ir(111) substrate at low temperature of 30 K, where no\nskyrmion was observed to form. Our findings signify the importance of diffusion\nof Fe atoms on the Ir(111) substrate, which affects the size, shape and lattice\nperfection of the Fe islands and thus the formation of skyrmion lattice."
    },
    {
        "anchor": "Coherent dynamics of localized excitons and trions in ZnO/(Zn,Mg)O\n  quantum wells studied by photon echoes: We study optically the coherent evolution of trions and excitons in a\n$\\delta$-doped 3.5 nm-thick ZnO/Zn$_{0.91}$Mg$_{0.09}$O multiple quantum well\nby means of time-resolved four-wave mixing at temperature of 1.5~K. Employing\nspectrally narrow picosecond laser pulses in the $\\chi^{(3)}$ regime allows us\nto address differently localized trion and exciton states, thereby avoiding\nmany-body interactions and excitation-induced dephasing. The signal in the form\nof photon echoes from the negatively charged A excitons (T$_\\text{A}$, trions)\ndecays with coherence times varying from 8 up to 60~ps, depending on the trion\nenergy: more strongly localized trions reveal longer coherence dynamics. The\nlocalized neutral excitons decay on the picosecond timescale with coherence\ntimes up to $T_2=4.5$~ps. The coherent dynamics of the X$_\\text{B}$ exciton and\nT$_\\text{B}$ trion are very short ($T_2<1$~ps), which is attributed to the fast\nenergy relaxation from the trion and exciton B states to the respective A\nstates. The trion population dynamics is characterized by the decay time $T_1$,\nrising from 30~ps to 100~ps with decreasing trion energy.",
        "positive": "Evidence for the Luttigger liquid density of states in transport across\n  the incompressible stripe at fractional filling factors: We experimentally investigate transport across the incompressible stripe at\nthe sample edge in the fractional quantum Hall effect regime at bulk filling\nfactors $\\nu=2/3$ and $\\nu=2/5$. We obtain the dependence of the equilibration\nlength, that is a phenomenological characteristics of the transport, on the\nvoltage imbalance and the temperature, at high voltage imbalances. These\ndependencies are found to be of the power-law form, which is a strong evidence\nfor the Luttigger liquid density of states."
    },
    {
        "anchor": "Polarization hydrodynamics in a one-dimensional polariton condensate: We study the hydrodynamics of a nonresonantly-pumped polariton condensate in\na quasi-one-dimensional quantum wire taking into account the spin degree of\nfreedom. We clarify the relevance of the Landau criterion for superfluidity in\nthis dissipative two-component system. Two Cherenkov-like critical velocities\nare identified corresponding to the opening of different channels of radiation:\none of (damped) density fluctuations and another of (weakly damped)\npolarization fluctuations. We determine the drag force exerted onto an external\nobstacle and propose experimentally measurable consequences of the specific\nfeatures of the fluctuations of polarization.",
        "positive": "Time-resolved pump-probe signals of a continuously driven quantum dot\n  affected by phonons: The interaction of a light field with a quantum-mechanical system can be\nstudied in an optically controlled semiconductor quantum dot. When driven by a\ncontinuous light field switched on instantaneously, the quantum dot occupation\nperforms Rabi oscillations. Unlike an atomic system, the quantum dot is coupled\nto phonons, which leads to a damping of the Rabi oscillations. Here we model\nthe time-resolved probe spectra to monitor these dynamics and study the\ninfluence of phonons on the spectra. The spectra consist of up to three peaks,\nsimilar to the Mollow-triplet known from quantum optics. We develop analytical\nequations within a rate equation model and show that they agree excellently\nwith a numerical solution using a well established correlation expansion\napproach."
    },
    {
        "anchor": "Evidence for high-temperature topological order in an asymmetric quantum\n  Hall system: Further experiments showed the incorrectness of proposed interpretation.",
        "positive": "Kondo effect in the Kohn-Sham conductance of multiple levels quantum\n  dots: At zero temperature, the Landauer formalism combined with static density\nfunctional theory is able to correctly reproduce the Kondo plateau in the\nconductance of the Anderson impurity model provided that an\nexchange-correlation potential is used which correctly exhibits steps at\ninteger occupation. Here we extend this recent finding to multi-level quantum\ndots described by the constant-interaction model. We derive the exact\nexchange-correlation potential in this model for the isolated dot and deduce an\naccurate approximation for the case when the dot is weakly coupled to two\nleads. We show that at zero temperature and for non-degenerate levels in the\ndot we correctly obtain the conductance plateau for any odd number of electrons\non the dot. We also analyze the case when some of the levels of the dot are\ndegenerate and again obtain good qualitative agreement with results obtained\nwith alternative methods. As in the case of a single level, for temperatures\nlarger than the Kondo temperature, the Kohn-Sham conductance fails to reproduce\nthe typical Coulomb blockade peaks. This is attributed to {\\em dynamical}\nexchange-correlation corrections to the conductance originating from\ntime-dependent density functional theory."
    },
    {
        "anchor": "Coherent and robust high-fidelity generation of a biexciton in a quantum\n  dot by rapid adiabatic passage: A biexciton in a semiconductor quantum dot is a source of\npolarization-entangled photons with high potential for implementation in\nscalable systems. Several approaches for non-resonant, resonant and\nquasi-resonant biexciton preparation exist, but all have their own\ndisadvantages, for instance low fidelity, timing jitter, incoherence or\nsensitivity to experimental parameters. We demonstrate a coherent and robust\ntechnique to generate a biexciton in an InGaAs quantum dot with a fidelity\nclose to one. The main concept is the application of rapid adiabatic passage to\nthe ground state-exciton-biexciton system. We reinforce our experimental\nresults with simulations which include a microscopic coupling to phonons.",
        "positive": "Long Distance Spin Transport in High Mobility Graphene on Hexagonal\n  Boron Nitride: We performed spin transport measurements on boron nitride based single layer\ngraphene devices with mobilities up to 40 000 cm${^2}$V$^{-1}$s$^{-1}$. We\ncould observe spin transport over lengths up to 20 {\\mu}m at room temperature,\nthe largest distance measured so far for graphene. Due to enhanced charge\ncarrier diffusion, spin relaxation lengths are measured up to 4.5 {\\mu}m. The\nrelaxation times are similar to values for lower quality SiO$_2$ based devices,\naround 200 ps. We find that the relaxation rate is determined in almost equal\nmeasures by the Elliott-Yafet and D'Yakonov-Perel mechanisms."
    },
    {
        "anchor": "The ultrafast dynamics and conductivity of photoexcited graphene at\n  different Fermi energies: For many of the envisioned optoelectronic applications of graphene it is\ncrucial to understand the sub-picosecond carrier dynamics immediately following\nphotoexcitation, as well as the effect on the electrical conductivity - the\nphotoconductivity. Whereas these topics have been studied using various\nultrafast experiments and theoretical approaches, controversial and incomplete\nexplanations have been put forward concerning the sign of the\nphotoconductivity, the occurrence and significance of the creation of\nadditional electron-hole pairs, and, in particular, how the relevant processes\ndepend on Fermi energy. Here, we present a unified and intuitive physical\npicture of the ultrafast carrier dynamics and the photoconductivity, combining\noptical pump - terahertz probe measurements on a gate-tunable graphene device,\nwith numerical calculations using the Boltzmann equation. We distinguish two\ntypes of ultrafast photo-induced carrier heating processes: At low\n(equilibrium) Fermi energy ($E_{\\rm F} \\lesssim$ 0.1 eV for our experiments)\nbroadening of the carrier distribution involves interband transitions -\ninterband heating. At higher Fermi energy ($E_{\\rm F} \\gtrsim$ 0.15 eV)\nbroadening of the carrier distribution involves intraband transitions -\nintraband heating. Under certain conditions, additional electron-hole pairs can\nbe created (carrier multiplication) for low $E_{\\rm F}$, and hot carriers\n(hot-carrier multiplication) for higher $E_{\\rm F}$. The resultant\nphotoconductivity is positive (negative) for low (high) $E_{\\rm F}$, which\noriginates from the effect of the heated carrier distributions on the screening\nof impurities, consistent with the DC conductivity being mostly due to impurity\nscattering. The importance of these insights is highlighted by a discussion of\nthe implications for graphene photodetector applications.",
        "positive": "Very Large and Reversible Stark Shift Tuning of Single Emitters in\n  Layered Hexagonal Boron Nitride: Combining solid state single photon emitters (SPE) with nanophotonic\nplatforms is a key goal in integrated quantum photonics. In order to realize\nfunctionality in potentially scalable elements, suitable SPEs have to be\nbright, stable, and widely tunable at room temperature. In this work we show\nthat selected SPEs embedded in a few layer hexagonal boron nitride (hBN) meet\nthese demands. In order to show the wide tunability of these SPEs we employ an\nAFM with a conductive tip to apply an electrostatic field to individual hBN\nemitters sandwiched between the tip and an indium tin oxide coated glass slide.\nA very large and reversible Stark shift of $(5.5 \\pm 3)\\,$nm at a zero field\nwavelength of $670\\,$nm was induced by applying just $20\\,$V, which exceeds the\ntypical resonance linewidths of nanodielectric and even nanoplasmonic\nresonators. Our results are important to further understand the physical origin\nof SPEs in hBN as well as for practical quantum photonic applications where\nwide spectral tuning and on/off resonance switching are required."
    },
    {
        "anchor": "Two-Dimensional Spintronic Circuit Architectures on Large Scale Graphene: Solid-state electronics based on utilizing the electron spin degree of\nfreedom for storing and processing information can pave the way for\nnext-generation spin-based computing. However, the realization of spin\ncommunication between multiple devices in complex spin circuit geometries,\nessential for practical applications, is still lacking. Here, we demonstrate\nthe spin current propagation in two-dimensional (2D) circuit architectures\nconsisting of multiple devices and configurations using a large area CVD\ngraphene on SiO2/Si substrate at room temperature. Taking advantage of the\nsignificant spin transport distance reaching 34 {\\mu}m in commercially\navailable wafer-scale graphene grown on Cu foil, we demonstrate that the spin\ncurrent can be effectively communicated between the magnetic memory elements in\ngraphene channels within 2D circuits of Y-junction and Hexa-arm architectures.\nWe further show that by designing graphene channels and ferromagnetic elements\nat different geometrical angles, the symmetric and antisymmetric components of\nthe Hanle spin precession signal can be remarkably controlled. These findings\nlay the foundation for the design of complex 2D spintronic circuits, which can\nbe integrated into efficient electronics based on the transport of pure spin\ncurrents.",
        "positive": "Quantum-well tunneling anisotropic magnetoresistance above room\n  temperature: Quantum-well (QW) devices have been extensively investigated in semiconductor\nstructures. More recently, spin-polarized QWs were integrated into magnetic\ntunnel junctions (MTJs). In this work, we demonstrate the spin-based control of\nthe quantized states in iron $3d$-band QWs, as observed in experiments and\ntheoretical calculations. We find that the magnetization rotation in the Fe QWs\nsignificantly shifts the QW quantization levels, which modulate the\nresonant-tunneling current in MTJs, resulting in a tunneling anisotropic\nmagnetoresistance (TAMR) effect of QWs. This QW-TAMR effect is sizable compared\nto other types of TAMR effect, and it is present above the room-temperature. In\na QW MTJ of Cr/Fe/MgAl$_2$O$_4$/top electrode, where the QW is formed by a\nmismatch between Cr and Fe in the $d$ band with $\\Delta_1$ symmetry, a QW-TAMR\nratio of up to 5.4 % was observed at 5 K, which persisted to 1.2 % even at\n380K. The magnetic control of QW transport can open new applications for\nspin-coupled optoelectronic devices, ultra-thin sensors, and memories."
    },
    {
        "anchor": "Theory of interlayer exciton dynamics in 2D TMDCs Heterolayers under the\n  influence of strain reconstruction and disorder: Monolayers of transition metal dichalcogenides (TMDC) became one of the most\nstudied nanostructures in the last decade. Combining two different TMDC\nmonolayers results in a heterostructure whose properties can be individually\ntuned by the twist angle between the lattices of the two van-der-Waals layers\nand the relative placement of the layers, leading to Moir\\'e cells. For small\ntwist angles, lattice reconstruction leads to strong strain fields in the\nMoir\\'e cells. In this paper, we combine an existing theory for lattice\nreconstruction with a quantum dynamic theory for interlayer excitons and their\ndynamics due to exciton phonon scattering using a polaron transformation. The\nexciton theory is formulated in real space instead of the commonly used\nquasi-momentum space to account for imperfections in the heterolayer breaking\nlattice translational symmetry. We can analyze the structure of the localized\nand delocalized exciton states and their exciton-phonon scattering rates for\nsingle phonon processes using Born-Markov approximation and multi-phonon\nprocesses using a polaron transformation. Furthermore, linear optical spectra\nand exciton relaxation Green functions are calculated and discussed. A\nP-stacked MoSe$_2$/WSe$_2$ heterolayer is used as an illustrative example. It\nshows excitons localized in the potential generated through the Moir\\'e-pattern\nand strain and a delocalized continuum. The exciton-phonon relaxation times\nvary depending on the strain and range from sub-pico seconds up to nanoseconds.",
        "positive": "Voltage controlled spin precession in InAs quantum wells: In this work we investigate spin diffusion in InAs quantum wells with the\nRashba spin-orbit coupling modulated by a gate voltage. The gate voltage\ndependence of the spin diffusion under different temperatures is studied with\nall the scattering explicitly included. Our result partially supports the claim\nof the realization of the Datta-Das spin-injected field effect transistor by\nKoo {\\it et al.} [Science {\\bf 325}, 1515 (2009)]. We also show that the\nscattering plays an important role in spin diffusion in such a system."
    },
    {
        "anchor": "Spintronic magnetic anisotropy: An attractive feature of magnetic adatoms and molecules for nanoscale\napplications is their superparamagnetism, the preferred alignment of their spin\nalong an easy axis preventing undesired spin reversal. The underlying magnetic\nanisotropy barrier --a quadrupolar energy splitting-- is internally generated\nby spin-orbit interaction and can nowadays be probed by electronic transport.\nHere we predict that in a much broader class of quantum-dot systems with spin\nlarger than one-half, superparamagnetism may arise without spin-orbit\ninteraction: by attaching ferromagnets a spintronic exchange field of\nquadrupolar nature is generated locally. It can be observed in conductance\nmeasurements and surprisingly leads to enhanced spin filtering even in a state\nwith zero average spin. Analogously to the spintronic dipolar exchange field,\nresponsible for a local spin torque, the effect is susceptible to electric\ncontrol and increases with tunnel coupling as well as with spin polarization.",
        "positive": "Magnetic qubits as hardware for quantum computers: We propose two potential realisations for quantum bits based on nanometre\nscale magnetic particles of large spin S and high anisotropy molecular\nclusters. In case (1) the bit-value basis states |0> and |1> are the ground and\nfirst excited spin states Sz = S and S-1, separated by an energy gap given by\nthe ferromagnetic resonance (FMR) frequency. In case (2), when there is\nsignificant tunnelling through the anisotropy barrier, the qubit states\ncorrespond to the symmetric, |0>, and antisymmetric, |1>, combinations of the\ntwo-fold degenerate ground state Sz = +- S. In each case the temperature of\noperation must be low compared to the energy gap, \\Delta, between the states\n|0> and |1>. The gap \\Delta in case (2) can be controlled with an external\nmagnetic field perpendicular to the easy axis of the molecular cluster. The\nstates of different molecular clusters and magnetic particles may be entangled\nby connecting them by superconducting lines with Josephson switches, leading to\nthe potential for quantum computing hardware."
    },
    {
        "anchor": "Large-Scale Integrated Vector-Matrix Multiplication Processor Based on\n  Monolayer MoS2: Led by the rise of the internet of things, the world is experiencing\nexponential growth of generated data. Data-driven algorithms such as signal\nprocessing and artificial neural networks are required to process and extract\nmeaningful information from it. They are, however, seriously limited by the\ntraditional von-Neuman architecture with physical separation between processing\nand memory, motivating the development of in-memory computing. This emerging\narchitecture is gaining attention by promising more energy-efficient computing\non edge devices. In the past few years, two-dimensional materials have entered\nthe field as a material platform suitable for realizing efficient memory\nelements for in-memory architectures. Here, we report a large-scale integrated\n32x32 vector-matrix multiplier with 1024 floating-gate field-effect transistors\n(FGFET) that use monolayer MoS2 as the channel material. In our wafer-scale\nfabrication process, we achieve a high yield and low device-to-device\nvariability, which are prerequisites for practical applications. A statistical\nanalysis shows the potential for multilevel and analog storage with a single\nprogramming pulse, allowing our accelerator to be programmed using an efficient\nopen-loop programming scheme. Next, we demonstrate reliable, discrete signal\nprocessing in a highly parallel manner. Our findings set the grounds for\ncreating the next generation of in-memory processors and neural network\naccelerators that can take advantage of the full benefits of semiconducting van\nder Waals materials for non-von Neuman computing.",
        "positive": "Dynamics of Spin Relaxation in Finite-Size 2D Systems: an Exact Solution: We find an exact solution for the problem of electron spin relaxation in a 2D\ncircle with Rashba spin-orbit interaction. Our analysis shows that the spin\nrelaxation in finite-size regions involves three stages and is described by\nmultiple spin relaxation times. It is important that the longest spin\nrelaxation time increases with decrease in system radius but always remains\nfinite. Therefore, at long times, the spin polarization in small 2D systems\ndecays exponentially with a size-dependent rate. This prediction is supported\nby results of Monte Carlo simulations."
    },
    {
        "anchor": "Quantum Decoherence of the Central Spin in a Sparse System of Dipolar\n  Coupled Spins: The central spin decoherence problem has been researched for over 50 years in\nthe context of both nuclear magnetic resonance and electron spin resonance.\nUntil recently, theoretical models have employed phenomenological stochastic\ndescriptions of the bath-induced noise. During the last few years, cluster\nexpansion methods have provided a microscopic, quantum theory to study the\nspectral diffusion of a central spin. These methods have proven to be very\naccurate and efficient for problems of nuclear-induced electron spin\ndecoherence in which hyperfine interactions with the central electron spin are\nmuch stronger than dipolar interactions among the nuclei. We provide an\nin-depth study of central spin decoherence for a canonical scale-invariant\nall-dipolar spin system. We show how cluster methods may be adapted to treat\nthis problem in which central and bath spin interactions are of comparable\nstrength. Our extensive numerical work shows that a properly modified cluster\ntheory is convergent for this problem even as simple perturbative arguments\nbegin to break down. By treating clusters in the presence of energy detunings\ndue to the long-range (diagonal) dipolar interactions of the surrounding\nenvironment and carefully averaging the effects over different spin states, we\nfind that the nontrivial flip-flop dynamics among the spins becomes effectively\nlocalized by disorder in the energy splittings of the spins. This localization\neffect allows for a robust calculation of the spin echo signal in a dipolarly\ncoupled bath of spins of the same kind, while considering clusters of no more\nthan 6 spins. We connect these microscopic calculation results to the existing\nstochastic models. We, furthermore, present calculations for a series of\nrelated problems of interest for candidate solid state quantum bits including\ndonors and quantum dots in silicon as well as nitrogen-vacancy centers in\ndiamond.",
        "positive": "Control of valley dynamics in silicon quantum dots in the presence of an\n  interface step: Recent experiments on silicon nanostructures have seen breakthroughs toward\nscalable, long-lived quantum information processing. The valley degree of\nfreedom plays a fundamental role in these devices, and the two lowest-energy\nelectronic states of a silicon quantum dot can form a valley qubit. In this\nwork, we show that a single-atom high step at the silicon/barrier interface\ninduces a strong interaction of the qubit and in-plane electric fields, and\nanalyze the consequences of this enhanced interaction on the dynamics of the\nqubit. The charge densities of the qubit states are deformed differently by the\ninterface step, allowing non-demolition qubit readout via valley-to-charge\nconversion. A gate-induced in-plane electric field together with the interface\nstep enables fast control of the valley qubit via electrically driven valley\nresonance. We calculate single- and two-qubit gate times, as well as relaxation\nand dephasing times, and present predictions for the parameter range where the\ngate times can be much shorter than the relaxation time and dephasing is\nreduced."
    },
    {
        "anchor": "Photodetectors based on junctions of Two-Dimensional Transition metal\n  dichalcogenides: Transition metal dichalcogenides (TMDCs) have gained considerable attention\nbecause of their novel properties and great potential applications. The flakes\nof TMDCs not only have great light absorptions from visible to near infrared,\nbut also can be stacked together regardless of lattice mismatch like other\ntwo-dimensional (2D) materials. Along with the studies on intrinsic properties\nof TMDCs, the junctions based on TMDCs become more and more important in\napplications of photodetection. The junctions have shown many exciting\npossibilities to fully combine the advantages of TMDCs, other 2D materials,\nconventional and organic semiconductors together. Early studies have greatly\nenriched the application of TMDCs in photodetection. In this review, we\ninvestigate the efforts in photodetectors based on the junctions of TMDCs and\nanalyze the properties of those photodetectors. Homojunctions based on TMDCs\ncan be made by surface chemical doping, elemental doping and electrostatic\ngating. Heterojunction formed between TMDCs/2D materials, TMDCs/conventional\nsemiconductors and TMDCs/organic semiconductor also deserve more attentions. We\nalso compare the advantages and disadvantages of different junctions, and then\ngive the prospects for the development of junctions based on TMDCs.",
        "positive": "Magnetic-field-induced singularities in spin dependent tunneling through\n  InAs quantum dots: Current steps attributed to resonant tunneling through individual InAs\nquantum dots embedded in a GaAs-AlAs-GaAs tunneling device are investigated\nexperimentally in magnetic fields up to 28 T. The steps evolve into strongly\nenhanced current peaks in high fields. This can be understood as a\nfield-induced Fermi-edge singularity due to the Coulomb interaction between the\ntunneling electron on the quantum dot and the partly spin polarized Fermi sea\nin the Landau quantized three-dimensional emitter."
    },
    {
        "anchor": "Vertical Field-Effect Transistor Based on Wavefunction Extension: We demonstrate a mechanism for a dual layer, vertical field-effect\ntransistor, in which nearly-depleting one layer will extend its wavefunction to\noverlap the other layer and increase tunnel current. We characterize this\neffect in a specially designed GaAs/AlGaAs device, observing a tunnel current\nincrease of two orders of magnitude at cryogenic temperatures, and we suggest\nextrapolations of the design to other material systems such as graphene.",
        "positive": "Fictitious gauge fields in bilayer graphene: We discuss the effect of elastic deformations on the electronic properties of\nbilayer graphene membranes. Distortions of the lattice translate into\nfictitious gauge fields in the electronic Dirac Hamiltonian which are\nexplicitly derived here for arbitrary elastic deformations. We include gauge\nfields associated to intra- as well as inter-layer hopping terms and discuss\ntheir effects in different contexts. As a first application, we use the gauge\nfields in order to study the recently predicted strain-induced Lifshitz\ntransition for the Fermi surface at low energy. As a second application, we\ndiscuss the electron-phonon coupling induced by the fictitious gauge fields and\nanalyse its contribution to the electrical resistivity of suspended bilayer\nmembranes. Of special interest is the appearance of a linear coupling for\nflexural modes, in stark contrast to the case of monolayer graphene. This new\ncoupling channel is shown to dominate the temperature-dependent resistivity in\nsuspended samples with low tension."
    },
    {
        "anchor": "Real-space Formalism for the Euler Class and Fragile Topology in\n  Quasicrystals and Amorphous Lattices: We propose a real-space formalism of the topological Euler class, which\ncharacterizes the fragile topology of two-dimensional systems with real wave\nfunctions. This real-space description is characterized by local Euler markers\nwhose macroscopic average coincides with the Euler number, and it applies\nequally well to periodic and open boundary conditions for both crystals and\nnoncrystalline systems. We validate this by diagnosing topological phase\ntransitions in clean and disordered crystalline systems with the reality\nendowed by the space-time inversion symmetry $\\mathcal{I}_{ST}$. Furthermore,\nwe demonstrated the topological Euler phases in quasicrystals and even in\namorphous lattices lacking any spatial symmetries. Our work not only provides a\nlocal characterization of the fragile topology but also significantly extends\nits territory beyond $\\mathcal{I}_{ST}$-symmetric crystalline materials.",
        "positive": "Quantum spin Hall insulator in proximity with a superconductor:\n  Transition to the Fulde-Ferrell-Larkin-Ovchinnikov state driven by a Zeeman\n  field: We investigate the effects of introducing a boost (a Zeeman field parallel to\nthe spin quantization axis) at the proximitized helical edge of a\ntwo-dimensional (2D) quantum spin Hall insulator. Our self-consistent analysis\nfinds that a Fulde-Ferrell-Larkin-Ovchinnikov (FFLO) superconducting phase may\nemerge at the edge when the boost is larger than a critical value tied to the\ninduced pairing gap. A non-trivial consequence of retaining the 2D bulk in the\nmodel is that this boundary FFLO state supports a finite magnetization as well\nas finite current (flowing along the edge). This has implications for a proper\ntreatment of the ultra-violet cutoff in analyses employing the effective\none-dimensional (1D) helical edge model. Our results may be contrasted with\nprevious studies of such 1D models, which found that the FFLO phase either does\nnot appear for any value of the boost (in non-self-consistent calculations), or\nthat it self-consistently appears even for infinitesimal boost, but carries no\ncurrent and magnetization."
    },
    {
        "anchor": "Robustness of n-GaAs Carrier Spin Properties to 5 MeV Proton Irradiation: Modern electronic devices utilize charge to transmit and store information.\nThis leaves the information susceptible to external influences, such as\nradiation, that can introduce short timescale charge fluctuations and, long\nterm, degrade electronic properties. Encoding information as spin polarizations\noffers an attractive alternative to electronic logic that should be robust to\nrandomly polarized transient radiation effects. As a preliminary step towards\nradiation-resistant spintronic devices, we measure the spin properties of\nn-GaAs as a function of radiation fluence using time-resolved Kerr rotation and\nphotoluminescence spectroscopy. Our results show a modest to negligible change\nin the long-term electron spin properties up to a fluence of 1x10$^{14}$ (5 MeV\nprotons)/cm$^2$, even as the luminescence decreases by two orders of magnitude.",
        "positive": "Giant Spin-valley Polarization and Multiple Hall Effect in\n  Functionalized Bi Monolayers: Valleytronic materials, characterized by local extrema (valley) in their\nbands, and topological insulators have separately attracted great interest\nrecently. However, the interplay between valleytronic and topological\nproperties in one single system, likely to enable important unexplored\nphenomena and applications, has been largely overlooked so far. Here, by\ncombining a tight-binding model with first-principles calculations, we find the\nlarge-band-gap quantum spin Hall effects (QSHEs) and valley Hall effects (VHEs)\nappear simultaneously in the Bi monolayers decorated with halogen elements,\ndenoted as Bi2XY (X, Y = H, F, Cl, Br, or I). A staggered exchange field is\nintroduced into the Bi2XY monolayers by transition metal atom (Cr, Mo, or W)\ndoping or LaFeO3 magnetic substrates, which together with the strong SOC of Bi\natoms generates a time-reversal-symmetry-broken QSHE and a huge valley\nsplitting (up to 513 meV) in the system. With gate control, QSHE and anomalous\ncharge, spin, valley Hall effects can be observed in the single system. These\npredicted multiple and exotic Hall effects, associated with various degrees of\nfreedom of electrons, could enable applications of the functionalized Bi\nmonolayers in electronics, spintronics, and valleytronics."
    },
    {
        "anchor": "Hot electron cooling by acoustic phonons in graphene: We have investigated the energy loss of hot electrons in metallic graphene by\nmeans of GHz noise thermometry at liquid helium temperature. We observe the\nelectronic temperature T / V at low bias in agreement with the heat diffusion\nto the leads described by the Wiedemann-Franz law. We report on\n$T\\propto\\sqrt{V}$ behavior at high bias, which corresponds to a T4 dependence\nof the cooling power. This is the signature of a 2D acoustic phonon cooling\nmechanism. From a heat equation analysis of the two regimes we extract accurate\nvalues of the electron-acoustic phonon coupling constant $\\Sigma$ in monolayer\ngraphene. Our measurements point to an important effect of lattice disorder in\nthe reduction of $\\Sigma$, not yet considered by theory. Moreover, our study\nprovides a strong and firm support to the rising field of graphene bolometric\ndetectors.",
        "positive": "Transport in a Single Self-Doped Nanocrystal: Addressing the optical properties of a single nanoparticle in the infrared is\nparticularly challenging, thus alternative methods for characterizing the\nconductance spectrum of nanoparticles in this spectral range need to be\ndeveloped. Here we describe an efficient method of fabricating single\nnanoparticle tunnel junctions on a chip circuit. We apply this method to narrow\nband gap nanoparticles of HgSe, which band structure combine the inverted\ncharacter of the bulk semimetal with quantum confinement and self-doping. Upon\ntuning the gate bias, measurement reveals the presence of two energy gaps in\nthe spectrum. The wider gap results from the interband gap, while the narrower\ngap results from intraband transitions. The observation of the latter near zero\ngate voltage confirms the doped character of the nanoparticle at the single\nparticle level, which is in full agreement with the ensemble optical and\ntransport measurements. Finally we probe the phototransport within a single\nquantum dot and demonstrate a large photogain mechanism resulting from\nphotogating."
    },
    {
        "anchor": "Stacking-Dependent Band Gap and Quantum Transport in Trilayer Graphene: In a multi-layer electronic system, stacking order provides a rarely-explored\ndegree of freedom for tuning its electronic properties. Here we demonstrate the\ndramatically different transport properties in trilayer graphene (TLG) with\ndifferent stacking orders. At the Dirac point, ABA-stacked TLG remains metallic\nwhile the ABC counterpart becomes insulating. The latter exhibits a gap-like\ndI/dV characteristics at low temperature and thermally activated conduction at\nhigher temperatures, indicating an intrinsic gap ~6 meV. In magnetic fields, in\naddition to an insulating state at filling factor {\\nu}=0, ABC TLG exhibits\nquantum Hall plateaus at {\\nu}=-30, \\pm 18, \\pm 9, each of which splits into 3\nbranches at higher fields. Such splittings are signatures of the Lifshitz\ntransition induced by trigonal warping, found only in ABC TLG, and in\nsemi-quantitative agreement with theory. Our results underscore the rich\ninteraction-induced phenomena in trilayer graphene with different stacking\norders, and its potential towards electronic applications.",
        "positive": "Group theory for structural analysis and lattice vibrations in\n  phosphorene systems: Group theory analysis for two-dimensional elemental systems related to\nphosphorene is presented, including (i) graphene, silicene, germanene and\nstanene, (ii) dependence on the number of layers and (iii) two stacking\narrangements. Departing from the most symmetric $D_{6h}^{1}$ graphene space\ngroup, the structures are found to have a group-subgroup relation, and analysis\nof the irreducible representations of their lattice vibrations makes it\npossible to distinguish between the different allotropes. The analysis can be\nused to study the effect of strain, to understand structural phase transitions,\nto characterize the number of layers, crystallographic orientation and\nnonlinear phenomena."
    },
    {
        "anchor": "Near-infrared optical properties and proposed phase-change usefulness of\n  transition metal disulfides: The development of photonic integrated circuits would benefit from a wider\nselection of materials that can strongly-control near-infrared (NIR) light.\nTransition metal dichalcogenides (TMDs) have been explored extensively for\nvisible spectrum opto-electronics, but the NIR properties of these layered\nmaterials have been less-studied. The measurement of optical constants is the\nforemost step to qualify TMDs for use in NIR photonics. Here we measure the\ncomplex optical constants for select sulfide TMDs (bulk crystals of MoS2, TiS2\nand ZrS2) via spectroscopic ellipsometry in the visible-to-NIR range. Through\nMueller matrix measurements and generalized ellipsometry, we explicitly measure\nthe direction of the ordinary optical axis. We support our measurements with\ndensity functional theory (DFT) calculations, which agree with our measurements\nand predict giant birefringence. We further propose that TMDs could find use as\nphotonic phase-change materials, by designing alloys that are thermodynamically\nadjacent to phase boundaries between competing crystal structures, to realize\nmartensitic (i.e. displacive, order-order) switching.",
        "positive": "Surface coating with oxide layers to enhance the spin properties of\n  shallow NV centers in diamond: We present an enhancement of spin properties of the shallow (<5nm) NV centers\nby using ALD to deposit titanium oxide layer on the diamond surface. With the\noxide layer of an appropriate thickness, increases about 2 up to 3.5 times of\nboth relaxation time and evolution time were achieved and the shallow NV center\ncharge states stabilized as well. Moreover, the coherence time kept almost\nunchanged. This surface coating technique could produce a protective coating\nlayer of controllable thickness without any damages to the solid quantum system\nsurface, making it possible to prolong T1 time and T2* time, which would be a\npossible approach to the further packaging technique for the applicating solid\nquantum devices."
    },
    {
        "anchor": "Electron-phonon vertex and its influence on the superconductivity of\n  two-dimensional metals on a piezoelectric substrate: We investigate the interaction between the electrons of a two-dimensional\nmetal and the acoustic phonons of an underlying piezoelectric substrate.\nFundamental inequalities can be obtained from general energy arguments. As a\nresult, phonon mediated attraction can be proven to never overcome electron\nCoulomb repulsion, at least for long phonon wavelengths. We study the influence\nof these phonons on the possible pairing instabilities of a two-dimensional\nelectron gas such as graphene.",
        "positive": "Gate-controlled Supercurrent in Ballistic InSb Nanoflag Josephson\n  Junctions: High-quality III-V narrow band gap semiconductor materials with strong\nspin-orbit coupling and large Lande g-factor provide a promising platform for\nnext-generation applications in the field of high-speed electronics,\nspintronics, and quantum computing. Indium Antimonide (InSb) offers a narrow\nband gap, high carrier mobility, and a small effective mass, and thus is very\nappealing in this context. In fact, this material has attracted tremendous\nattention in recent years for the implementation of topological superconducting\nstates supporting Majorana zero modes. However, high-quality heteroepitaxial\ntwo-dimensional (2D) InSb layers are very diffcult to realize owing to the\nlarge lattice mismatch with all commonly available semiconductor substrates. An\nalternative pathway is the growth of free-standing single-crystalline 2D InSb\nnanostructures, the so-called nanoflags. Here we demonstrate fabrication of\nballistic Josephson-junction devices based on InSb nanoflags with Ti/Nb\ncontacts that show gate-tunable proximity-induced supercurrent up to 50 nA at\n250 mK and a sizable excess current. The devices show clear signatures of\nsubharmonic gap structures, indicating phase-coherent transport in the junction\nand a high transparency of the interfaces. This places InSb nanoflags in the\nspotlight as a versatile and convenient 2D platform for advanced quantum\ntechnologies."
    },
    {
        "anchor": "Kekule Lattice in Graphdiyne: Coexistence of Phononic and Electronic\n  Higher-Order Band Topology: The topological physics has been extensively studied in different kinds of\nbosonic and fermionic systems, ranging from artificial structures to natural\nmaterials. However, the coexistence of topological phonon and electron in one\nsingle material is seldom reported. Recently, graphdiyne is proposed to be a\ntwo-dimensional (2D) electronic second-order topological insulator (SOTI). In\nthis work, based on density-functional tight-binding calculations, we found\nthat graphdiyne is equivalent to the Kekule lattice, also realizing a 2D\nphononic SOTI in both out-of-plane and in-plane modes. Depending on edge\nterminations, the characterized topological corner states can be either inside\nor outside the bulk gap, which are tunable by local corner potential. Most\nremarkably, a unique selectivity of space and symmetry is revealed in\nelectron-phonon coupling between the localized phononic and electronic\ntopological corner states. Our results not only demonstrate the phononic\nhigher-order band topology in a real carbon material, but also provide an\nopportunity to investigate the interplay between phononic and electronic\nhigher-order topological states.",
        "positive": "Quantum Phase Slip Noise: Quantum phase slips (QPS) generate voltage fluctuations in superconducting\nnanowires. Employing Keldysh technique and making use of the phase-charge\nduality arguments we develop a theory of QPS-induced voltage noise in such\nnanowires. We demonstrate that quantum tunneling of the magnetic flux quanta\nacross the wire yields quantum shot noise which obeys Poisson statistics and is\ncharacterized by a power law dependence of its spectrum $S_\\Omega$ on the\nexternal bias. In long wires $S_\\Omega$ decreases with increasing frequency\n$\\Omega$ and vanishes beyond a threshold value of $\\Omega$ at $T \\to 0$.\nQuantum coherent nature of QPS noise yields non-monotonous dependence of\n$S_\\Omega$ on $T$ at small $\\Omega$."
    },
    {
        "anchor": "Phonon Angular Momentum Induced by Temperature Gradient: Phonon modes in crystals can have angular momenta in general. It nevertheless\ncancels in equilibrium when the time-reversal symmetry is preserved. In this\npaper we show that when a temperature gradient is applied and heat current\nflows in the crystal, the phonon distribution becomes off-equilibrium, and a\nfinite angular momentum is generated by the heat current. This mechanism is\nanalogous to the Edelstein effect in electronic systems. This effect requires\ncrystals with sufficiently low crystallographic symmetries, such as polar or\nchiral crystal structures. Because of the positive charges of the nuclei, this\nphonon angular momentum induces magnetization. In addition, when the crystal\ncan freely rotate, this generated phonon angular momentum is converted to a\nrigidbody rotation of the crystal, due to the conservation of the total angular\nmomentum. Furthermore, in metallic crystals, the phonon angular momentum will\nbe partially converted into spin angular momentum of electrons.",
        "positive": "Defect-induced band restructuring and length scales in twisted bilayer\n  graphene: We investigate the effects of single, multiple, and extended defects in the\nform of non-magnetic impurities and vacancies in twisted bilayer graphene (TBG)\nat and away from the magic angle, using a fully atomistic model and focusing on\nthe behavior of the flat low-energy moir\\'e bands. For strong impurities and\nvacancies in the $AA$ region we find a complete removal of one of the four\nmoir\\'e bands, resulting in a significant depletion of the charge density in\nthe $AA$ regions even at extremely low defect concentrations. We find similar\nresults for other defect locations, with the exception of the least coordinated\nsites in the $AB$ region, where defects instead result in a peculiar band\nreplacement process within the moir\\'e bands. In the vacancy limit, this\nprocess yields a band structure misleadingly similar to the pristine case.\nMoreover, we show that triple point fermions (TPFs), which are the crossing of\nthe Dirac point by a flat band, appearing for single, periodic, defects, are\ngenerally not preserved when adding extended or multiple defects, and thus\nlikely not experimentally relevant. We further identify two universal length\nscales for defects, consisting of charge modulations on the atomic scale and on\nthe moir\\'e scale, illustrating the importance of both the atomic and moir\\'e\nstructures for understanding TBG. We show that our conclusions hold beyond the\nmagic angle and for fully isolated defects. In summary, our results demonstrate\nthat the normal state of TBG and its moir\\'e flat bands are extremely sensitive\nto both the location and strength of non-magnetic impurities and vacancies,\nwhich should have significant implications for any emergent ordered state."
    },
    {
        "anchor": "Full counting statistics applied to dissipative Cooper pair pumping: We calculate the charge transport in a flux biased dissipative Cooper pair\npump using the method of full counting statistics (FCS). This is instead of a\nmore traditional technique of integrating a very small expectation value of the\ninstantaneous current over the pumping period. We show that the rotating wave\napproximation (RWA), which fails in the traditional technique, produces\naccurate results within the FCS method.",
        "positive": "Spin-dependent tunnelling through a symmetric barrier: The problem of electron tunnelling through a symmetric semiconductor barrier\nbased on zinc-blende-structure material is studied. The $k^3$ Dresselhaus terms\nin the effective Hamiltonian of bulk semiconductor of the barrier are shown to\nresult in a dependence of the tunnelling transmission on the spin orientation.\nThe difference of the transmission probabilities for opposite spin orientations\ncan achieve several percents for the reasonable width of the barriers."
    },
    {
        "anchor": "Spins coupled to a Spin Bath: From Integrability to Chaos: Motivated by the hyperfine interaction of electron spins with surrounding\nnuclei, we investigate systems of central spins coupled to a bath of\nnoninteracting spins in the framework of random matrix theory. With increasing\nnumber of central spins a transition from Poissonian statistics to the Gaussian\northogonal ensemble occurs which can be described by a generalized Brody\ndistribution. These observations are unaltered upon applying an external\nmagnetic field. In the transition region, the classical counterparts of the\nmodels studied have mixed phase space.",
        "positive": "Optical orientation of excitons in a longitudinal magnetic field in\n  indirect band gap (In,Al)As/AlAs quantum dots with type-I band alignment: The exciton recombination and spin dynamics in (In,Al)As/AlAs quantum dots\n(QDs) with indirect band gap and type-I band alignment are studied. The\nnegligible (less than $0.2~\\mu$eV) value of the anisotropic exchange\ninteraction in these QDs prevents a mixing of the excitonic basis states with\npure spin and allows for the formation of spin polarized bright excitons for\nquasi-resonant circularly polarized excitation. In a longitudinal magnetic\nfield, the recombination and spin dynamics of the excitons are controlled by\nthe hyperfine interaction between the electron and nuclear spins. A QD blockade\nby dark excitons is observed in magnetic field eliminating the impact of the\nnuclear spin fluctuations. A kinetic equation model, which accounts for the\npopulation dynamics of the bright and dark exciton states as well as for the\nspin dynamics, has been developed, which allows for a quantitative description\nof the experimental data."
    },
    {
        "anchor": "Quantum noise theory for phonon transport through nanostructures: We have developed a quantum noise approach to study the phonon transport\nthrough nanostructures. The nanostructures acting as phonon channels are\nattached to two phonon reservoirs. And the temperature drop between the two\nreservoirs drives the phonon transport through the channels. We have derived a\nquantum Langevin equation(QLE) to describe the phonon transport with the\nquantum noise originated from the thermal fluctuation of the reservoirs. Within\nthe Markov approximation, the QLE is used to get the thermal conductivity\n$\\kappa$ of the nanostructures and the finite size effect of the $\\kappa$ then\nis studied. In this study, the advantage of the quantum noise approach lays on\nthe fact that no any local temperature needs to be defined for the\nnanostructures in its non-equilibrium state.",
        "positive": "Compact SQUID realized in a double layer graphene heterostructure: Two-dimensional systems that host one-dimensional helical states are exciting\nfrom the perspective of scalable topological quantum computation when coupled\nwith a superconductor. Graphene is particularly promising for its high\nelectronic quality, versatility in van der Waals heterostructures and its\nelectron and hole-like degenerate 0$th$ Landau level. Here, we study a compact\ndouble layer graphene SQUID (superconducting quantum interference device),\nwhere the superconducting loop is reduced to the superconducting contacts,\nconnecting two parallel graphene Josephson junctions. Despite the small size of\nthe SQUID, it is fully tunable by independent gate control of the Fermi\nenergies in both layers. Furthermore, both Josephson junctions show a skewed\ncurrent phase relationship, indicating the presence of superconducting modes\nwith high transparency. In the quantum Hall regime we measure a well defined\nconductance plateau of 2$e^2/h$ an indicative of counter propagating edge\nchannels in the two layers. Our work opens a way for engineering topological\nsuperconductivity by coupling helical edge states, from graphene's\nelectron-hole degenerate 0$th$ Landau level via superconducting contacts."
    },
    {
        "anchor": "A Schottky top-gated two-dimensional electron system in a nuclear spin\n  free Si/SiGe heterostructure: We report on the realization and top-gating of a two-dimensional electron\nsystem in a nuclear spin free environment using 28Si and 70Ge source material\nin molecular beam epitaxy. Electron spin decoherence is expected to be\nminimized in nuclear spin-free materials, making them promising hosts for\nsolid-state based quantum information processing devices. The two-dimensional\nelectron system exhibits a mobility of 18000 cm2/Vs at a sheet carrier density\nof 4.6E11 cm-2 at low temperatures. Feasibility of reliable gating is\ndemonstrated by transport through split-gate structures realized with palladium\nSchottky top-gates which effectively control the two-dimensional electron\nsystem underneath. Our work forms the basis for the realization of an\nelectrostatically defined quantum dot in a nuclear spin free environment.",
        "positive": "Origin of Spinel Nanocheckerboards via First Principles: Self-organizing nanocheckerboards have been experimentally fabricated in\nMn-based spinels, but have not yet been explained with first principles. Using\ndensity-functional-theory, we explain the phase diagram of the\n$\\mathrm{ZnMn_xGa_{2-x}O_4}$ system and the origin of nanocheckerboards. We\npredict total phase separation at zero temperature, then show the combination\nof kinetics, thermodynamics, and Jahn-Teller physics that generates the\nsystem's observed behavior. We find the {011} surfaces are strongly-preferred\nenergetically, which mandates checkerboard ordering by purely geometrical\nconsiderations."
    },
    {
        "anchor": "Low-Temperature Annihilation Rate for Quasi-Localized Excitons in\n  Monolayer MoS2: The strong Coulomb forces in monolayer transition metal dichalcogenides\nensure that optical excitation of band electrons gives rise to Wannier-Mott\nexcitonic states, each of which can be conceptualized as a composite of a\nGaussian wavepacket corresponding to center-of-mass motion and an orbital state\ncorresponding to the motion of the electron and hole about the center-of-mass.\nHere, we show that at low temperature in monolayer MoS2, given quasi-localized\nexcitons and consequently a significant inter-exciton spacing, the excitons\nundergo dipole-dipole interaction and annihilate one another in a manner\nanalogous to Auger recombination. To construct our model, we assume that each\nexciton is localized in a region whose length is on the same scale as the\nexcitonic diameter, thus causing the exciton to behave in a fermionic manner,\nwhile the distance between neighboring excitons is much larger than the exciton\ndiameter. We construct the orbital ladder operators for each exciton and apply\nFermi's Golden Rule to derive the overall recombination rate as a function of\nexciton density.",
        "positive": "Optical properties and electron transport in low-dimensional\n  nanostructures: We present the theory of the electronic transfer and the optical properties\nof the quasi-zero dimensional quantum nanostructures, like quantum dots or the\nDNA molecule. The theory is based on the multiple scattering of the charge\ncarriers in the quasi-zero dimensional nanostructures leading to the\nmanifestation of the nonadiabatic influence of the atomic lattice on the charge\ncarriers. The theory is based on the nonequilibrium Green's functions and the\nquantum kinetic equations. Three examples of the electronic motion in the small\nsystems are presented, together with a comparison of the theoretical results\nwith their experimental counterparts. The comparison with the experiments\nunderlines importance of the electron-phonon interaction in nanostructures."
    },
    {
        "anchor": "A Gapless Symmetry-Protected Topological Phase of Fermions in One\n  Dimension: We consider a one-dimensional, time-reversal-invariant system with attractive\ninteractions and spin-orbit coupling. Such a system is gapless due to the\nstrong quantum fluctuations of the superconducting order parameter. However, we\nshow that a sharply defined topological phase with protected, exponentially\nlocalized edge states exists. If one of the spin components is conserved, the\nprotection of the edge modes can be understood as a consequence of the presence\nof a spin gap. In the more general case, the localization of the edge states\narises from a gap to single particle excitations in the bulk. We consider\nspecific microscopic models and demonstrate both analytically and numerically\n(using density matrix renormalization group calculations) that they can support\nthe topologically non-trivial phase.",
        "positive": "Hyperfine-controlled domain-wall motion observed in real space and time: We perform real-space imaging of propagating magnetic domains in the\nfractional quantum Hall system using spin-sensitive photoluminescence\nmicroscopy. The propagation is continuous and proceeds in the direction of the\nconventional current, i.e. opposite to the electron flow direction. The\nmechanism of motion is shown to be connected to polarized nuclear spins around\nthe domain walls. The propagation velocity increases when nuclei are\ndepolarized, and decreases when the source-drain current generating this\nnuclear polarization is increased. We discuss how these phenomena may arise\nfrom spin interactions along the domain walls."
    },
    {
        "anchor": "Effective fluctuation theorems for electron transport in a double\n  quantum dot coupled to a quantum point contact: A theoretical study is reported of electron transport at finite temperature\nin a double quantum dot (DQD) capacitively coupled to a quantum point contact\n(QPC). Starting from a Hamiltonian model, a master equation is obtained for the\nstochastic process taking place in the DQD while the QPC is at or away from\nequilibrium, allowing us to study the backaction of the QPC onto the DQD. The\nQPC is treated non-perturbatively in our analysis. Effective fluctuation\ntheorems are established for the full counting statistics of the DQD current\nunder different limiting conditions. These fluctuation theorems hold with\nrespect to an effective affinity characterizing the nonequilibrium environment\nof the DQD and differing from the applied voltage if the QPC is out of\nequilibrium. The effective affinity may even change its sign if the Coulomb\ndrag of the QPC reverses the DQD current. The thermodynamic implications of the\neffective fluctuation theorems are discussed.",
        "positive": "Stability of longitudinal coupling for Josephson charge qubits: For inductively coupled superconducting quantum bits, we determine the\nconditions when the coupling commutes with the single-qubit terms. We show that\nin certain parameter regimes such longitudinal coupling can be stabilized with\nrespect to variations of the circuit parameters. In addition, we analyze its\nstability against fluctuations of the control fields."
    },
    {
        "anchor": "Effects of quantum interference on the electron transport in the\n  semiconductor$/$benzene$/$semiconductor junction: Using the tight-binding model and the generalized Green's function formalism,\nthe effect of quantum interference on the electron transport through the\nbenzene molecule in a semiconductor/benzene/semiconductor junction is\nnumerically investigated. We show how the quantum interference sources,\ndifferent contact positions and local gate, can control the transmission\ncharacteristics of the electrode/molecule/electrode junction. We also study the\noccurrence of anti-resonant states in the transmission probability function\nusing a simple graphical scheme (introduced in Ref.[Phys. Chem. Chem. Phys,\n2011, 13, 1431]) for different geometries of the contacts between the benzene\nmolecule and semiconductor(silicon and titanium dioxide) electrodes.",
        "positive": "Phase Boundary of the Boson Mott Insulator in a Rotating Optical Lattice: We consider the Bose-Hubbard model in a two dimensional rotating optical\nlattice and investigate the consequences of the effective magnetic field\ncreated by rotation. Using a Gutzwiller type variational wavefunction, we find\nan analytical expression for the Mott insulator(MI)-Superfluid(SF) transition\nboundary in terms of the maximum eigenvalue of the Hofstadter butterfly. The\ndependence of phase boundary on the effective magnetic field is complex,\nreflecting the self-similar properties of the single particle energy spectrum.\nFinally, we argue that fractional quantum Hall phases exist close to the MI-SF\ntransition boundaries, including MI states with particle densities greater than\none."
    },
    {
        "anchor": "A facile direct device transfer of monolayer MoS2 towards improvement in\n  transistor performances: Transfer techniques based on two dimensional (2D) materials and devices offer\nimmense potential towards their industrial integration with the existing\nsilicon based electronics. To achieve high quality devices, there is an urgent\nrequirement for the etching-free, and clean transfer that retain original\nsemiconducting properties of layered channel materials. In parallel, transfer\nof metal electrode arrays on the 2D semiconductors also attract attention\ntowards large-scale integration for commercial applications. Here, we\ndemonstrate a facile PMMA-assisted etching-free one-step approach to transfer\nboth 2D channels and metal electrodes without damaging the contact region. The\ndirect device transfer (DDT) technique enables residue-free monolayer MoS2 as\nchannel material towards achieving doping-free intrinsic transistors with\nenhanced performances. The crystalline quality, strain relaxation, and\ninterfacial coupling effects are studied using Raman and photoluminescence\nspectra with spatial mapping. Post device transfer, a reduced pinning effect is\nobserved by the effective modulation of gate tunable drain currents in MoS2\ntransistors at room temperature. Furthermore, the extracted Schottky barrier\nheights, temperature dependence of threshold voltage shifts, hysteresis\nevolution, and mobility enhancements validates the improved transistor\nperformances in transferred devices. The proposed DDT method can be utilized to\ndirectly transfer array of devices of 2D materials and heterostructures\nskipping various cumbersome steps in between and hence could offer high\nperformance reliable electronic applications.",
        "positive": "Annihilation of exceptional points from different Dirac valleys in a 2D\n  photonic system: Topological physics relies on the existence of Hamiltonian's eigenstate\nsingularities carrying a topological charge, such as quantum vortices, Dirac\npoints, Weyl points and -- in non-Hermitian systems -- exceptional points\n(EPs), lines or surfaces. They appear only in pairs connected by a Fermi arc\nand are related to a Hermitian singularity, such as a Dirac point. The\nannihilation of 2D Dirac points carrying opposite charges has been\nexperimentally reported. It remained elusive for Weyl points and second order\nEPs terminating different Fermi arcs. Here, we observe the annihilation of\nsecond order EPs issued from different Dirac points forming distinct valleys.\nWe study a liquid crystal microcavity with voltage-controlled birefringence and\nTE-TM photonic spin-orbit-coupling. Two neighboring modes can be described by a\ntwo-band Hermitian Hamiltonian showing two topological phases with either two\nsame-sign or four opposite-sign Dirac points (valleys). Non-Hermiticity is\nprovided by polarization-dependent losses, which split Dirac points into pairs\nof EPs, connected by Fermi arcs. We measure their topological charges and\ncontrol their displacement in reciprocal space by increasing the\nnon-Hermiticity degree. EPs of opposite charges from different valleys meet and\nannihilate, connecting in a closed line the different Fermi arcs. This\nnon-Hermitian topological transition occurs only when the Hermitian part of the\nHamiltonian is topologically trivial (with four valleys), but is distinct from\nthe Hermitian transition. Our results offer new perspectives of versatile\nmanipulation of EPs, opening the new field of non-Hermitian valley-physics."
    },
    {
        "anchor": "A new decomposition of the Kubo-Bastin formula: The Smrcka-Streda version of Kubo's linear response formula is widely used in\nthe literature to compute non-equilibrium transport properties of\nheterostructures. It is particularly useful for the evaluation of intrinsic\ntransport properties associated with the Berry curvature of the Bloch states,\nsuch as anomalous and spin Hall currents as well as the damping-like component\nof the spin-orbit torque. Here, we demonstrate in a very general way that the\nwidely used decomposition of the Kubo-Bastin formula introduced by Smrcka and\nStreda contains an overlap, which has lead to widespread confusion in the\nliterature regarding the Fermi surface and Fermi sea contributions. To remedy\nthis pathology, we propose a new decomposition of the Kubo-Bastin formula based\non the permutation properties of the correlation function and derive a new set\nof formulas, without an overlap, that provides direct access to the transport\neffects of interest. We apply these new formulas to selected cases and\ndemonstrate that the Fermi sea and Fermi surface contributions can be uniquely\naddressed with our symmetrized approach.",
        "positive": "Statistics of skyrmions and the 5/2 puzzle: 1) For the hard core interaction there is some freedom left in the choice of\nthe exact multiskyrmionic wave function's topology. The statistics of textured\nquasiholes, analyzed by calculation of the Berry phase, depends on this choice\nof topology.\n  2) We find a class of textured two-hole eigenstates of the Coulomb\ninteraction. There is no definite quantum statistics but there is a definite\nrule of how to construct Coulomb eigenstates out of the hard core wave\nfunctions.\n  3) A wave function for the 5/2 state is constructed according to this rule."
    },
    {
        "anchor": "Adiabatic Control of the Electron Phase in a Quantum Dot: A Berry phase can be added to the wavefunction of an isolated quantum dot by\nadiabatically modulating a nonuniform electric field along a time-cycle. The\ndot is tuned close to a three-level degeneracy, which provides a wide range of\npossibilities of control. We propose to detect the accumulated phase by\ncapacitively coupling the dot to a double-path inteferometer. The effective\nHamiltonian for the phase-sensitive coupling is discussed in detail.",
        "positive": "Phonon-assisted optical absorption of SiC polytypes from first\n  principles: Silicon carbide (SiC) is an indirect-gap semiconductor material widely used\nin electronic and optoelectronic applications. While experimental measurements\nof the phonon-assisted absorption coefficient of SiC across its indirect gap\nhave existed for more than fifty years, theoretical investigations of\nphonon-assisted absorption have been hampered by their excessive computational\ncost. In this work, we calculate the phonon-assisted temperature-dependent\noptical absorption spectra of the commonly occurring SiC polytypes (3C, 2H, 4H\nand 6H), using first-principles approaches based on density functional theory\nand related techniques. We show that our results agree with experimentally\ndetermined absorption coefficients in the spectral region between the direct\nand indirect band gaps. The temperature dependence of the spectra can be\nwell-predicted with taking the temperature-dependence of the band gaps into\naccount. Lastly, we compare the spectra obtained with second-order perturbation\ntheory to those determined by the special displacement method, and we show that\nthe full consideration of the electronic energy renormalization due to\ntemperature is important to further improve the prediction of the\nphonon-assisted absorption in SiC. Our insights can be applied to predict the\noptical spectra of the less common SiC polytypes and other indirect-gap\nsemiconductors in general."
    },
    {
        "anchor": "Strain Control of Magnetism in Transition-Metal-Atom Decorated Graphene: We report a strain-controlled tuning of magnetism in\ntransition-metal-atom-decorated graphene. Our first-principles calculations\ndemonstrate that strain can lead to a sudden change in the magnetic\nconfiguration of a transition metal (TM) adatom and the local atomic structure\nin the sur- rounding graphene layer, which have a dramatic effect on the\neffective exchange coupling between neighboring TM atoms. A strong\nspin-dependent hybridization between TM d and graphene 1/4 orbital states,\nderived from the orbital selection rule of the local lattice symmetry, is\nresponsible for the determination of the local electronic and magnetic\nstructure. Our results indicate that the strain can be an effective way to\ncontrol the magnetism of atomic-scale nanostructures, where the reliable\ncontrol of their magnetic states is a key step for the future spintronic\napplications.",
        "positive": "On the propagation of Dirac fermions in graphene with the strain-induced\n  inhomogeneous Fermi velocity: We consider systems described by the two-dimensional Dirac equation where the\nFermi velocity is inhomogeneous as a consequence of mechanical deformations. We\nshow that the mechanical deformations can lead to deflection and focusing of\nthe wave packets. The analogy with known reflectionless quantum systems is\npointed out. Furthermore, with the use of the qualitative spectral analysis, we\ndiscuss how inhomogeneous strains can be used to create waveguides for valley\npolarized transport of partially dispersionless wave packets."
    },
    {
        "anchor": "Interplay Between Electron Over-Heating and ac Josephson Effect: We study the response of high-critical current proximity Josephson junctions\nto a microwave excitation. Electron over-heating in such devices is known to\ncreate hysteretic dc voltage-current characteristics. Here we demonstrate that\nit also strongly influences the ac response. The interplay of electron\nover-heating and ac Josephson dynamics is revealed by the evolution of the\nShapiro steps with the microwave drive amplitude. Extending the resistively\nshunted Josephson junction model by including a thermal balance for the\nelectronic bath coupled to phonons, a strong electron over-heating is obtained.",
        "positive": "Stationary states of an electron in periodic structures in a constant\n  uniform electrical field: On the basis of the transfer matrix technique an analytical method to\ninvestigate the stationary states, for an electron in one-dimensional periodic\nstructures in an external electrical field, displaying the symmetry of the\nproblem is developed. These solutions are shown to be current-carrying. It is\nalso shown that the electron spectrum for infinite structures is continuous,\nand the corresponding wave functions do not satisfy the symmetry condition of\nthe problem."
    },
    {
        "anchor": "Time dependent heat flow in interacting quantum conductors: We derive the frequency-resolved heat current expression in the linear\nresponse regime for a setup comprised of reservoir, interacting central site,\nand tunneling barrier under the action of a time dependent electrical signal.\nWe exploit the frequency parity properties of response functions to obtain the\nheat current expression for interacting quantum conductors. Importantly, the\ncorresponding heat formula, valid for arbitrary AC frequencies, can describe\nphoton-assisted heat transport. In particular, we analyze the heat transfer for\nan interacting multilevel conductor (a carbon nanotube quantum dot) coupled to\na single reservoir. We show that the electrothermal admittance can reverse its\nsign by properly tunning the AC frequency.",
        "positive": "Near-band-gap photo-induced nuclear spin dynamics in semi-insulating\n  GaAs: Hyperfine- and quadrupolar-driven relaxation: Understanding and manipulating spin polarization and transport in the\nvicinity of semiconductor-hosted defects is a problem of present technological\nand fundamental importance. Here, we use high-field magnetic resonance to\nmonitor the relaxation dynamics of spin-3/2 nuclei in semi-insulating GaAs. Our\nexperiments benefit from the conditions created in the limit of low\nillumination intensities, where intermittent occupation of the defect site by\nphoto-excited electrons leads to electric field gradient fluctuations and\nconcomitant spin relaxation of the neighboring quadrupolar nuclei. We find\nindication of a heterogeneous distribution of polarization, governed by\ndifferent classes of defects activated by either weak or strong laser\nexcitation. Upon application of a train of light pulses of variable repetition\nrate and on/off ratio, we uncover an intriguing regime of mesoscale nuclear\nspin diffusion restricted by long-range, non-uniform electric field gradients.\nGiven the slow time scale governing nuclear spin evolution, such\noptically-induced polarization patterns could be exploited as a contrast\nmechanism to expose dark lattice defects or localized charges with nanoscale\nresolution."
    },
    {
        "anchor": "Ballistic Josephson junctions in edge-contacted graphene: Hybrid graphene-superconductor devices have attracted much attention since\nthe early days of graphene research. So far, these studies have been limited to\nthe case of diffusive transport through graphene with poorly defined and modest\nquality graphene-superconductor interfaces, usually combined with small\ncritical magnetic fields of the superconducting electrodes. Here we report\ngraphene based Josephson junctions with one-dimensional edge contacts of\nMolybdenum Rhenium. The contacts exhibit a well defined, transparent interface\nto the graphene, have a critical magnetic field of 8 Tesla at 4 Kelvin and the\ngraphene has a high quality due to its encapsulation in hexagonal boron\nnitride. This allows us to study and exploit graphene Josephson junctions in a\nnew regime, characterized by ballistic transport. We find that the critical\ncurrent oscillates with the carrier density due to phase coherent interference\nof the electrons and holes that carry the supercurrent caused by the formation\nof a Fabry-P\\'{e}rot cavity. Furthermore, relatively large supercurrents are\nobserved over unprecedented long distances of up to 1.5 $\\mu$m. Finally, in the\nquantum Hall regime we observe broken symmetry states while the contacts remain\nsuperconducting. These achievements open up new avenues to exploit the Dirac\nnature of graphene in interaction with the superconducting state.",
        "positive": "Are the Tonks regimes in the continuum and on the lattice truly\n  equivalent?: Motivated by recent experiments, we compare the Tonks (i.e. hard-core boson\ngas) regime achieved in an optical lattice with the Tonks regime of a\none-dimensional Bose gas in the continuum. For the lattice gas, we compute the\nlocal (i.e. on-site) two-body correlations as a function of temperature and the\nfilling of the lattice. It is found that this function saturates to a constant\nvalue with increasing temperature. Furthermore, the parameter that\ncharacterizes the long-distance correlations in the lattice Tonks regime is\nalso obtained, showing that on the lattice the long-distance correlations enter\nthe Tonks regime more rapidly than in the continuum."
    },
    {
        "anchor": "Entanglement and quantum state engineering in the optically driven\n  two-electron double-dot structure: We study theoretically the quantum dynamics of two interacting electrons in\nthe symmetric double-dot structure under the influence of the bichromatic\nresonant pulse. The state vector evolution is studied for two different pulse\ndesigns. It is shown that the laser pulse can generate the effective exchange\ncoupling between the electron spins localized in different dots. Possible\napplications of this effect to the quantum information processing (entanglement\ngeneration, quantum state engineering) are discussed.",
        "positive": "Superfluidity of \"dirty\" indirect excitons and magnetoexcitons in\n  two-dimensional trap: The superfluid phase transition of bosons in a two-dimensional (2D) system\nwith disorder and an external parabolic potential is studied. The theory is\napplied to experiments on indirect excitons in coupled quantum wells. The\nrandom field is allowed to be large compared to the dipole-dipole repulsion\nbetween excitons. The slope of the external parabolic trap is assumed to change\nslowly enough to apply the local density approximation (LDA) for the superfluid\ndensity, which allows us to calculate the Kosterlitz-Thouless temperature\n$T_{c}(n(r))$ at each local point $r$ of the trap. The superfluid phase occurs\naround the center of the trap ($\\mathbf{r}=0$) with the normal phase outside\nthis area. As temperature increases, the superfluid area shrinks and disappears\nat temperature $T_{c}(n(r=0))$. Disorder acts to deplete the condensate; the\nminimal total number of excitons for which superfluidity exists increases with\ndisorder at fixed temperature. If the disorder is large enough, it can destroy\nthe superfluid entirely. The effect of magnetic field is also calculated for\nthe case of indirect excitons. In a strong magnetic field $H$, the superfluid\ncomponent decreases, primarily due to the change of the exciton effective mass."
    },
    {
        "anchor": "Magnetic field control of antiferromagnetic domain walls in a thermal\n  gradient: An antiferromagnetic domain wall in a thermal gradient is found to experience\na force towards colder regions upon the application of a uniform magnetic field\nalong the easy axis. This force increases with the strength of the applied\nfield and, for sufficiently high values, it overcomes the entropic force the\nthat pushes wall towards the hotter regions. The force is proportional to the\nthermal gradient and it shows a linear dependence with the net magnetic moment\nof the domain wall induced by the field. The origin of this force lies on the\nincrease of the domain wall reflectivity due the field-induced sizable break of\nantiferromagnetic order inside it, which turns it into an efficient barrier for\nmagnons, which transfer linear momentum to the domain wall when they are\nreflected on it",
        "positive": "Scanning Tunneling Spectroscopy of Graphene on Graphite: We report low temperature high magnetic field scanning tunneling microscopy\nand spectroscopy of graphene flakes on graphite that exhibit the structural and\nelectronic properties of graphene decoupled from the substrate. Pronounced\npeaks in the tunneling spectra develop with field revealing a Landau level\nsequence that provides a direct way to identify graphene and to determine the\ndegree of its coupling to the substrate. The Fermi velocity and quasiparticle\nlifetime, obtained from the positions and width of the peaks, provide access to\nthe electron-phonon and electron-electron interactions."
    },
    {
        "anchor": "High cumulants in the counting statistics measured for a quantum dot: We report on measurements of single electron tunneling through a quantum dot\nusing a quantum point contact as non-invasive charge detector with fast time\nresponse. We elaborate on the unambiguous identification of individual\ntunneling events and determine the distribution of transferred charges, the\nso-called full counting statistics. We discuss our data analysis, including the\nerror estimates of the measurement, and show that the quality of our\nexperimental results is sufficiently high to extract cumulants of the\ndistribution up to the 20th order for short times.",
        "positive": "Imaging the Thermalization of Hot Carriers After Thermionic Emission\n  Over a Polytype Barrier: The thermalization of non-equilibrium charge carriers is at the heart of\nthermoelectric energy conversion. In nanoscale systems, the equilibration\nlength can be on the order of the system size, leading to a situation where\nthermoelectric effects need to be considered as spatially distributed, rather\nthan localized at junctions. The energy exchange between charge carriers and\nphonons is of fundamental scientific and technological interest, but their\nassessment poses significant experimental challenges. We addressed these\nchallenges by imaging the temperature change induced by Peltier effects in\ncrystal phase engineered InAs nanowire (NW) devices. Using high-resolution\nscanning thermal microscopy (SThM), we have studied current-carrying InAs NWs,\nwhich feature a barrier segment of wurtzite (WZ) of varying length in a NW of\notherwise zincblende (ZB) crystal phase. The energy barrier acts as a filter\nfor electron transport around the Fermi energy, giving rise to a thermoelectric\neffect. We find that thermalization through electron-phonon heat exchange\nextends over the entire device. We analyze the temperature profile along a\nnanowire by comparing it to spatially dependent heat diffusion and electron\nthermalization models. We are able to extract the governing properties of the\nsystem, including the electron thermalization length of $223 \\pm 9$\\,nm,\nPeltier coefficient and Seebeck coefficient introduced by the barrier of $39\n\\pm 7$\\,mV and $89 \\pm 21$\\,$\\mu$V/K, respectively, and a thermal conductivity\nalong the wire axis of $8.9 \\pm 0.5$\\,W/m/K. Finally, we compare two ways to\nextract the elusive thermal boundary conductance between NW and underlying\nsubstrate."
    },
    {
        "anchor": "Definitive Surface Magnetotransport Study of SmB$_{6}$: After the theoretical prediction that SmB$_6$ is a topological Kondo\ninsulator, there has been an explosion of studies on the SmB$_6$ surface.\nHowever, there is not yet an agreement on even the most basic quantities such\nas the surface carrier density and mobility. In this paper, we carefully\nrevisit Corbino disk magnetotransport studies to find those surface transport\nparameters. We first show that subsurface cracks exist in the SmB$_6$ crystals,\narising both from surface preparation and during the crystal growth. We provide\nevidence that these hidden subsurface cracks are additional conduction\nchannels, and the large disagreement between earlier surface SmB$_6$ studies\nmay originate from previous interpretations not taking this extra conduction\npath into account. We provide an update of a more reliable magnetotransport\ndata than the previous one (Phys. Rev. B 92, 115110) and find that the\norders-of-magnitude large disagreements in carrier density and mobility come\nfrom the surface preparation and the transport geometry rather than the\nintrinsic sample quality. From this magnetotransport study, we find an updated\nestimate of the carrier density and mobility of 2.71$\\times$10$^{13}$\n(1/cm$^2$) and 104.5 (cm$^{2}$/V$\\cdot$sec), respectively. We compare our\nresults with other studies of the SmB$_6$ surface. By this comparison, we\nprovide insight into the disagreements and agreements of the previously\nreported angle-resolved photoemission spectroscopy, scanning tunneling\nmicroscopy, and magnetotorque quantum oscillations measurements.",
        "positive": "A CMOS silicon spin qubit: Silicon, the main constituent of microprocessor chips, is emerging as a\npromising material for the realization of future quantum processors. Leveraging\nits well-established complementary metal-oxide-semiconductor (CMOS) technology\nwould be a clear asset to the development of scalable quantum computing\narchitectures and to their co-integration with classical control hardware. Here\nwe report a silicon quantum bit (qubit) device made with an industry-standard\nfabrication process. The device consists of a two-gate, p-type transistor with\nan undoped channel. At low temperature, the first gate defines a quantum dot\n(QD) encoding a hole spin qubit, the second one a QD used for the qubit\nreadout. All electrical, two-axis control of the spin qubit is achieved by\napplying a phase-tunable microwave modulation to the first gate. Our result\nopens a viable path to qubit up-scaling through a readily exploitable CMOS\nplatform."
    },
    {
        "anchor": "Magnetic focusing of charge carriers from spin-split bands: Semiclassics\n  of a Zitterbewegung effect: We present a theoretical study of the interplay between cyclotron motion and\nspin splitting of charge carriers in solids. While many of our results apply\nmore generally, we focus especially on discussing the Rashba model describing\nelectrons in the conduction band of asymmetric semiconductor heterostructures.\nAppropriate semiclassical limits are distinguished that describe various\nsituations of experimental interest. Our analytical fomulae, which take full\naccount of Zeeman splitting, are used to analyse recent magnetic-focusing data.\nSurprisingly, it turns out that the Rashba effect can dominate the splitting of\ncyclotron orbits even when the Rashba and Zeeman spin-splitting energies are of\nthe same order. We also find that the origin of spin-dependent cyclotron motion\ncan be traced back to Zitterbewegung-like oscillatory dynamics of charge\ncarriers from spin-split bands. The relation between the two phenomena is\ndiscussed, and we estimate the effect of Zitterbewegung-related corrections to\nthe charge carriers' canonical position.",
        "positive": "Spaser Action, Loss Compensation, and Stability in Plasmonic Systems\n  with Gain: We demonstrate that the conditions of spaser generation and the full loss\ncompensation in a resonant plasmonic-gain medium (metamaterial) are identical.\nConsequently, attempting the full compensation or overcompensation of losses by\ngain will lead to instability and a transition to a spaser state. This will\nlimit (clamp) the inversion and lead to the limitation on the maximum loss\ncompensation achievable. The criterion of the loss overcompensation, leading to\nthe instability and spasing, is given in a analytical and universal\n(independent from system's geometry) form."
    },
    {
        "anchor": "A New Method for Characterizing Bulk and Surface Conductivities of\n  Three-Dimensional Topological Insulators: Inverted Resistance Measurements: We introduce a new resistance measurement method that is useful in\ncharacterizing materials with both surface and bulk conduction, such as\nthree-dimensional topological insulators. The transport geometry for this new\nresistance measurement configuration consists of one current lead as a closed\nloop that fully encloses the other current lead on the surface, and two voltage\nleads that are both placed outside the loop. We show that in the limit where\nthe transport is dominated by the surface conductivity of the material, the\nfour-terminal resistance measured from such a transport geometry is\nproportional to $\\sigma_b/\\sigma_s^2$, where $\\sigma_b$ and $\\sigma_s$ are the\nbulk and surface conductivities of the material, respectively. We call this new\ntype of measurement \\textit{inverted resistance measurement}, as the resistance\nscales inversely with the bulk resistivity. We discuss possible implementations\nof this new method by performing numerical calculations on different geometries\nand introduce strategies to extract the bulk and surface conductivities. We\nalso demonstrate inverted resistance measurements on SmB$_6$, a topological\nKondo insulator, using both single-sided and coaxially-aligned double-sided\nCorbino disk transport geometries. Using this new method, we are able to\nmeasure the bulk conductivity, even at low temperatures, where the bulk\nconduction is much smaller than the surface conduction in this material.",
        "positive": "Magnetothermoelectric properties of Bi2Se3: We present a study of entropy transport in Bi2Se3 at low temperatures and\nhigh magnetic fields. In the zero-temperature limit, the magnitude of the\nSeebeck coefficient quantitatively tracks the Fermi temperature of the 3D Fermi\nsurface at \\Gamma-point as the carrier concentration changes by two orders of\nmagnitude (10$^{17}$ to 10$^{19}$cm$^{-3}$). In high magnetic fields, the\nNernst response displays giant quantum oscillations indicating that this\nfeature is not exclusive to compensated semi-metals. A comprehensive analysis\nof the Landau Level spectrum firmly establishes a large $g$-factor in this\nmaterial and a substantial decrease of the Fermi energy with increasing\nmagnetic field across the quantum limit. Thus, the presence of bulk carriers\nsignificantly affects the spectrum of the intensively debated surface states in\nBi2Se3 and related materials."
    },
    {
        "anchor": "Anisotropic Zeeman splitting in p-type GaAs quantum point contacts: Low-temperature electrical conductance spectroscopy measurements of quantum\npoint contacts implemented in p-type GaAs/AlGaAs heterostructures are used to\nstudy the Zeeman splitting of 1D subbands for both in-plane and out-of-plane\nmagnetic field orientations. The resulting in-plane g-factors agree\nqualitatively with those of previous experiments on quantum wires while the\nquantitative differences can be understood in terms of the enhanced quasi-1D\nconfinement anisotropy. The influence of confinement potential on the\nanisotropy is discussed and an estimate for the out-of-plane g-factor is\nobtained which, in contrast to previous experiments, is closer to the\ntheoretical prediction.",
        "positive": "Ballistic dynamics of a convex smooth-wall billiard with finite escape\n  rate along the boundary: We focus on the problem of an impurity-free billiard with a random\nposition-dependent boundary coupling to the environment. The response functions\nof such an open system can be obtained non-perturbatively from a supersymmetric\ngenerating functional. The derivation of this functional is based on averaging\nover the escape rates and results in a non-linear ballistic $\\sigma $-model,\ncharacterized by system-specific parameters. Particular emphasis is placed on\nthe {}``whispering gallery modes'' as the origin of surface diffusion modes in\nthe limit of large dimensionless conductance."
    },
    {
        "anchor": "Evidence for a quantum-spin-Hall phase in graphene decorated with Bi2Te3\n  nanoparticles: Realization of the quantum-spin-Hall effect in graphene devices has remained\nan outstanding challenge dating back to the inception of the field of\ntopological insulators. Graphene's exceptionally weak spin-orbit coupling\n-stemming from carbon's low mass- poses the primary obstacle. We experimentally\nand theoretically study artificially enhanced spin-orbit coupling in graphene\nvia random decoration with dilute Bi2Te3 nanoparticles. Remarkably,\nmulti-terminal resistance measurements suggest the presence of helical edge\nstates characteristic of a quantum-spin-Hall phase; the magnetic-field and\ntemperature dependence of the resistance peaks, X-ray photoelectron spectra,\nscanning tunneling spectroscopy, and first-principles calculations further\nsupport this scenario. These observations highlight a pathway to spintronics\nand quantum-information applications in graphene-based quantum-spin-Hall\nplatforms.",
        "positive": "Current noise of a resonant tunnel junction coupled to a nanomechanical\n  oscillator: We present a theoretical study of current noise of a resonant tunnel junction\ncoupled to a nanomechanical oscillator within the non-equilibrium Green's\nfunction technique. An arbitrary voltage is applied to the tunnel junction and\nelectrons in the leads are considered to be at zero temperature. The properties\nof the phonon distribution of the nanomechanical oscillator strongly coupled to\nthe electrons on the dot are investigated using a non-perturbative approach. An\nanalytical calculations and numerical results for the current-voltage, shot\nnoise and the corresponding Fano factor as a function of applied bias show\nsignificant features of the nanomechanical oscillator coupling dynamics. This\nwill provide useful insight for the design of experiments aimed at studying the\nquantum behavior of an oscillator."
    },
    {
        "anchor": "Resonant tunneling in disordered borophene nanoribbons with line defects: Very recently, borophene has been attracting extensive and ongoing interest\nas the new wonder material with structural polymorphism and superior\nattributes, showing that the structural imperfection of line defects (LDs)\noccurs widely at the interface between $\\nu_{1/5}$ ($\\chi_3$) and $\\nu_{1/6}$\n($\\beta_{12}$) boron sheets. Motivated by these experiments, here we present a\ntheoretical study of electron transport through two-terminal disordered\nborophene nanoribbons (BNRs) with random distribution of LDs. Our results\nindicate that LDs could strongly affect the electron transport properties of\nBNRs. In the absence of LDs, both $\\nu_{1/5}$ and $\\nu_{1/6}$ BNRs exhibit\nmetallic behavior, in agreement with experiments. While in the presence of LDs,\nthe overall electron transport ability is dramatically decreased, but some\nresonant peaks of conductance quantum can be found in the transmission spectrum\nof any disordered BNR with arbitrary arrangement of LDs. These disordered BNRs\nexhibit metal-insulator transition by varying nanoribbon width with tunable\ntransmission gap in the insulating regime. Furthermore, the bond currents\npresent fringe patterns and two evolution phenomena of resonant peaks are\nrevealed for disordered BNRs with different widths. These results may help for\nunderstanding structure-property relationships and designing LD-based\nnanodevices.",
        "positive": "Extra Current and Integer Quantum Hall Conductance in the Spin-Orbit\n  Coupling System: We study the extra term of particle current in a 2D k-cubic Rashba spin-orbit\ncoupling system and the integer quantization of the Hall conductance in this\nsystem. We provide a correct formula of charge current in this system and the\ncareful consideration of extra currents provides a stronger theoretical basis\nfor the theory of the quantum Hall effect which has not been considered before.\nThe non-trivial extra contribution to the particle current density and local\nconductivity, which originates from the cubic dependence on the momentum\noperator in the Hamiltonian, will have no effect on the integer quantization of\nthe Hall conductance. The extension of Noether's theorem for the 2D k-cubic\nRashba system is also addressed. The two methods reach to exactly the same\nresults."
    },
    {
        "anchor": "Crossed Andreev reflection versus electron transfer in graphene\n  nanoribbons: We investigate the transport properties of three-terminal graphene devices,\nwhere one terminal is superconducting and two are normal metals. The terminals\nare connected by nanoribbons. Electron transfer (ET) and crossed Andreev\nreflection (CAR) are identified via the non-local signal between the two normal\nterminals. Analytical expressions for ET and CAR in symmetric devices are\nfound. We compute ET and CAR numerically for asymmetric devices. ET dominates\nCAR in symmetric devices, but CAR can dominate ET in asymmetric devices, where\nonly the zero-energy modes of the zigzag nanoribbons contribute to the\ntransport.",
        "positive": "Real Non-Hermitian Energy Spectra Without Any Symmetry: Non-Hermitian models with real eigenenergies are highly desirable for their\nstability. Yet, most of the currently known ones are constrained by symmetries\nsuch as PT-symmetry, which is incompatible with realizing some of the most\nexotic non-Hermitian phenomena. In this work, we investigate how the\nnon-Hermitian skin effect provides an alternative route towards enforcing real\nspectra and system stability. We showcase, for different classes of energy\ndispersions, various ansatz models that possess large parameter space regions\nwith real spectra, despite not having any obvious symmetry. These minimal local\nmodels can be quickly implemented in non-reciprocal experimental setups such as\nelectrical circuits with operational amplifiers."
    },
    {
        "anchor": "Floquet topological system based on frequency-modulated classical\n  coupled harmonic oscillators: We theoretically propose how to observe topological effects in a generic\nclassical system of coupled harmonic oscillators, such as classical pendula or\nlumped-element electric circuits, whose oscillation frequency is modulated fast\nin time. Making use of Floquet theory in the high frequency limit, we identify\na regime in which the system is accurately described by a Harper-Hofstadter\nmodel where the synthetic magnetic field can be externally tuned via the phase\nof the frequency-modulation of the different oscillators. We illustrate how the\ntopologically-protected chiral edge states, as well as the Hofstadter butterfly\nof bulk bands, can be observed in the driven-dissipative steady state under a\nmonochromatic drive. In analogy with the integer quantum Hall effect, we show\nhow the topological Chern numbers of the bands can be extracted from the mean\ntransverse shift of the steady-state oscillation amplitude distribution.\nFinally we discuss the regime where the analogy with the Harper-Hofstadter\nmodel breaks down.",
        "positive": "Fidelity and Entanglement of a Spatially Extended Linear Three-Qubit\n  Register: We study decoherence of a three-qubit array coupled to substrate phonons.\nAssuming an initial three-qubit entangled state that would be decoherence-free\nfor identical qubit positions, allows us to focus on non-Markovian effects of\nthe inevitable spatial qubit separation. It turns out that the coherence is\nmost affected when the qubits are regularly spaced. Moreover, we find that up\nto a constant scaling factor, two-qubit entanglement is not influenced by the\npresence f the third qubit, even though all qubits interact via the phonon\nfield."
    },
    {
        "anchor": "Uncovering the spin ordering in magic-angle graphene via edge state\n  equilibration: Determining the symmetry breaking order of correlated quantum phases is\nessential for understanding the microscopic interactions in their host systems.\nThe flat bands in magic angle twisted bilayer graphene (MATBG) provide an\nespecially rich arena to investigate such interaction-driven ground states, and\nwhile progress has been made in identifying the correlated insulators and their\nexcitations at commensurate moire filling factors, the spin-valley\npolarizations of the topological states that emerge at high magnetic field\nremain unknown. Here we introduce a new technique based on twist-decoupled van\nder Waals layers that enables measurements of their electronic band structure\nand, by studying the backscattering between counter-propagating edge states,\ndetermination of relative spin polarization of the their edge modes. Applying\nthis method to twist-decoupled MATBG and monolayer graphene, we find that the\nbroken-symmetry quantum Hall states that extend from the charge neutrality\npoint in MATBG are spin-unpolarized at even integer filling factors. The\nmeasurements also indicate that the correlated Chern insulator emerging from\nhalf filling of the flat valence band is spin-unpolarized, but suggest that its\nconduction band counterpart may be spin-polarized. Our results constrain models\nof spin-valley ordering in MATBG and establish a versatile approach to study\nthe electronic properties of van der Waals systems.",
        "positive": "Electronic Cooling in Graphene: Energy transfer to acoustic phonons is the dominant low-temperature cooling\nchannel of electrons in a crystal.For cold neutral graphene we find that the\nweak cooling power of its acoustical modes relative to the heat capacity of the\nsystem leads to a power law decay of the electronic temperature when far from\nequilibrium. For heavily doped graphene a high electronic temperature is shown\nto initially decrease linearly with time at a rate proportional to n^(3/2) with\nn being the electronic density. We discuss the relative importance of optical\nand acoustic phonons to cooling."
    },
    {
        "anchor": "Charge Distribution in a Kondo Correlated Quantum Dot: We report here on a direct and non-invasive measurement of the charge and its\ndistribution in a Kondo correlated quantum dot (QD). A non-invasive\npotential-sensitive detector in proximity with the QD reveals that even though\nthe conductance of the QD is significantly enhanced as it enters the Kondo\nregime the net charge in the QD remains unaffected. This demonstrates the\nseparation between spin and charge degrees of freedom in the Kondo effect. We\nfind however, under certain experimental conditions, that an abrupt\nredistribution of the charge in the QD is taking place simultaneously with the\nonset of Kondo correlation. This suggests that the spin-charge separation in\nthe Kondo effect does not always hold.",
        "positive": "Strain in crystalline core-shell nanowires: The strain configuration induced by the lattice mismatch in a core-shell\nnanowire is calculated analytically, taking into account the crystal anisotropy\nand the difference in stiffness constants of the two materials. The method is\napplied to nanowires with the wurtzite structure or the zinc-blende structure\nwith the hexagonal / trigonal axis along the nanowire, and the results are\ncompared to available numerical calculations and experimental data. It is also\napplied to multishell nanowires, and to core-shell nanowires grown along the\n$<001>$ axis of cubic semiconductors."
    },
    {
        "anchor": "Vibration-induced modulation of magnetic anisotropy in a magnetic\n  molecule: We theoretically analyze the spectrum of a magnetic molecule when its charge\nand spin can couple to the molecular vibrations. More specifically, we show\nthat the interplay between charge-vibron and spin-vibron coupling leads to a\nrenormalization of the magnetic anisotropy parameters of the molecule. This\neffect is discussed for a model device consisting of an individual magnetic\nmolecule embedded in a junction. We study the transport properties of the\ndevice and illustrate how the differential conductance is affected by the\nvibrationally induced renormalization of the magnetic anisotropy. Depending on\nthe total molecular spin and the bare (intrinsic) magnetic anisotropy, the\ninduced modulation can lead to visible shifts and crossings in the spectrum,\nand it can even be the cause of a transport blockade. It is therefore of\nparticular interest to use mechanically controllable break junctions, since in\nsuch a case, the relevant coupling between the molecular spin and vibrations\ncan be controlled via deformations of the molecule when stretching or\ncompressing the junction.",
        "positive": "Spintronics in half-passivated graphene: In this thesis, I propose a practical way to stabilize half passivated\ngraphene (graphone). I show that the dipole moments induced by a\nhexagonal-boron nitride (h-BN) substrate on graphene stabilize the hydrogen\natoms on one sublattice of the graphene layer and suppress the migration of the\nadsorbed hydrogen atoms. I also present the substrate effect of h-BN that\nreduces distortion induced by fluorination of graphene and stabilizes\nhalf-passivated graphene in a single sublattice. Then using spin-polarized\ndensity functional calculations I investigate magnetic properties of graphone.\nI show the system has different magnetic order which can be described by either\nsuper-exchange or double exchange mechanisms depending on the type the of add\natom. The hybridization of graphene changes from $sp^2$- to $sp^3$- type\nhybridization due to the buckling induced by passivation. The change in\nhybridization together with add-atom orbitals induces a fairly large spin orbit\ncoupling (SOC). Based upon first principle spin-polarized density of states\ncalculations, I show that the graphone obtained in different graphene/h-BN\nheterostructures exhibits a half metallic state. I propose to use this exotic\nmaterial for spin valve systems and other spintronics devices."
    },
    {
        "anchor": "Temperature-dependent electron mobility in InAs nanowires: Effective electron mobilities are obtained by transport measurements on InAs\nnanowire field-effect transistors at temperatures ranging from 10-200 K. The\nmobility increases with temperature below ~ 30 - 50 K, and then decreases with\ntemperature above 50 K, consistent with other reports. The magnitude and\ntemperature dependence of the observed mobility can be explained by Coulomb\nscattering from ionized surface states at typical densities. The behaviour\nabove 50 K is ascribed to the thermally activated increase in the number of\nscatterers, although nanoscale confinement also plays a role as higher radial\nsubbands are populated, leading to interband scattering and a shift of the\ncarrier distribution closer to the surface. Scattering rate calculations using\nfinite-element simulations of the nanowire transistor confirm that these\nmechanisms are able to explain the data.",
        "positive": "The signature of subsurface Kondo impurities in the local tunnel current: The conductance of a tunnel point-contact in an STM-like geometry having a\nsingle defect placed below the surface is investigated theoretically. The\neffect of multiple electron scattering by the defect after reflections by the\nmetal surface is taken into account. In the approximation of s-wave scattering\nthe dependence of the conductance on the applied voltage and the position of\nthe defect is obtained. The results are illustrated for a model s-wave phase\nshift describing Kondo-resonance scattering. We demonstrate that multiple\nelectron scattering by the magnetic impurity plays a decisive role in the\npoint-contact conductance at voltages near the Kondo resonance. We find that\nthe sign and shape of the Kondo anomaly depends on the position of the defect."
    },
    {
        "anchor": "Cavity Quantum Electrodynamics at Arbitrary Light-Matter Coupling\n  Strengths: Quantum light-matter systems at strong coupling are notoriously challenging\nto analyze due to the need to include states with many excitations in every\ncoupled mode. We propose a nonperturbative approach to analyze light-matter\ncorrelations at all interaction strengths. The key element of our approach is a\nunitary transformation that achieves asymptotic decoupling of light and matter\ndegrees of freedom in the limit where light-matter interaction becomes the\ndominant energy scale. In the transformed frame, truncation of the\nmatter/photon Hilbert space is increasingly well-justified at larger coupling,\nenabling one to systematically derive low-energy effective models, such as\ntight-binding Hamiltonians. We demonstrate the versatility of our approach by\napplying it to concrete models relevant to electrons in crystal potential and\nelectric dipoles interacting with a cavity mode. A generalization to the case\nof spatially varying electromagnetic modes is also discussed.",
        "positive": "Current-induced synchronized magnetization reversal of two-body Stoner\n  particles with dipolar interaction: We investigate magnetization reversal of two-body uniaxial Stoner particles,\nby injecting spin-polarized current through a spin-valve structure. The\ntwo-body Stoner particles perform synchronized dynamics and can act as an\ninformation bit in computer technology. In the presence of magnetic\ndipole-dipole interaction (DDI) between the two particles, the critical\nswitching current $I_c$ for reversing the two dipoles is analytically obtained\nand numerically verified in two typical geometric configurations. $I_c$\nbifurcates at a critical DDI strength, where $I_c$ can be decreased to about\n70% of the usual value without DDI. Moreover, we also numerically investigate\nthe magnetic hysteresis loop, magnetization self-precession, reversal time and\nthe synchronization stability phase diagram for the two-body system in the\nsynchronized dynamics regime."
    },
    {
        "anchor": "Transport properties of spin-triplet superconducting monolayer $MoS_2$: The quantum transport properties of graphene and monolayer $MoS_2$\nsuperconductor heterostructures has been of considerable importance in the\nrecent few years. Layered nature of molybdenum disulfide permits the\nsuperconducting correlation induction. Moreover, peculiar dynamical features of\nmonolayer $MoS_2$, such as valence band spin-splitting in the nondegenerate $K$\nand $K'$ valleys originated from strong spin-orbit coupling, and considerable\ndirect band gap can make it potentially a useful material for electronics\napplications. Using the Dirac-like Hamiltonian of $MoS_2$ with taking into\naccount the related mass asymmetry and topological contributions, we\ninvestigate the effect of spin-triplet $p$-wave pairing symmetry on the\nsuperconducting excitations, resulting in Andreev reflection process and\nAndreev bound state in the corresponding normal-superconductor (NS) and\nsuperconductor-normal-superconductor (SNS) structures, respectively. We study\nhow the resulting subgap conductance and Josephson current are affected by the\nparticular symmetry of order parameter. The signature of $p_x$-wave symmetry is\nfound to decline the subgap superconducting energy excitations and,\nconsequently, slightly suppress the Andreev reflection in the case of $p$-doped\nS region. The essential dynamical parameters $\\lambda$ and $\\beta$ of $MoS_2$\nhave significant effect on the both tunneling conductance and Josephson\ncurrent. Particularly, the considered $p$-wave symmetry in the superconducting\nbound energies may feature the zero energy states at the interfaces. The\ncritical current oscillations as a function of length of junction are obtained\nin the $p$-doped S region.",
        "positive": "Magnetic Nanoparticle Assemblies: This chapter provides an introduction to the fundamental physical ideas and\nmodels relevant to the phenomenon of magnetic hysteresis in nanoparticle\nassemblies. The concepts of single-domain particles and superparamagnetism are\ndiscussed. The mechanisms of magnetization by coherent rotation and the role of\ntemperature in the gradual decay of magnetization are analyzed in the framework\nof simple analytical models. Modern numerical techniques (Monte Carlo\nsimulations, Magnetization Dynamics) used to study dense nanoparticle\nassemblies are presented. An overview of the most common experimental\ntechniques used to measure the magnetic hysteresis effect in nanoparticle\nassemblies are presented and the underlying principles are exposed."
    },
    {
        "anchor": "Dephasing time in graphene due to interaction with flexural phonons: We investigate decoherence of an electron in graphene caused by\nelectron-flexural phonon interaction. We find out that flexural phonons can\nproduce dephasing rate comparable to the electron-electron one. The problem\nappears to be quite special because there is a large interval of temperature\nwhere the dephasing induced by phonons can not be obtain using the golden rule.\nWe evaluate this rate for a wide range of density ($n$) and temperature ($T$)\nand determine several asymptotic regions with temperature dependence crossing\nover from $\\tau_{\\phi }^{-1}\\sim T^{2}$ to $\\tau_{\\phi}^{-1}\\sim T$ when\ntemperature increases. We also find $\\tau_{\\phi}^{-1}$ to be a non-monotonous\nfunction of $n$. These distinctive features of the new contribution can provide\nan effective way to identify flexural phonons in graphene through the\nelectronic transport by measuring the weak localization corrections in\nmagnetoresistance.",
        "positive": "The Role of Correlation in the Operation of Quantum-dot Cellular\n  Automata: Quantum-dot Cellular Automata (QCA) may offer a viable alternative of\ntraditional transistor-based technology at the nanoscale. When modeling a QCA\ncircuit, the number of degrees of freedom necessary to describe the quantum\nmechanical state increases exponentially making modeling even modest size cell\narrays difficult. The intercellular Hartree approximation largely reduces the\nnumber of state variables and still gives good results especially when the\nsystem remains near ground state. This suggests that large part of the\ncorrelation degrees of freedom are not essential from the point of view of the\ndynamics. In certain cases, however, such as for example the majority gate with\nunequal input legs, the Hartree approximation gives qualitatively wrong\nresults. An intermediate model is constructed between the Hartree approximation\nand the exact model, based on the coherence vector formalism. By including\ncorrelation effects to a desired degree, it improves the results of the Hartree\nmethod and gives the approximate dynamics of the correlation terms. It also\nmodels the majority gate correctly. Beside QCA cell arrays, our findings are\nvalid for Ising spin chains in transverse magnetic field, and can be\nstraightforwardly generalized for coupled two-level systems with a more\ncomplicated Hamiltonian."
    },
    {
        "anchor": "Shubnikov-de Haas oscillations of a single layer graphene under dc\n  current bias: Shubnikov-de Haas (SdH) oscillations under a dc current bias are\nexperimentally studied on a Hall bar sample of single layer graphene. In dc\nresistance, the bias current shows the common damping effect on the SdH\noscillations and the effect can be well accounted for by an elevated electron\ntemperature that is found to be linearly dependent on the current bias. In\ndifferential resistance, a novel phase inversion of the SdH oscillations has\nbeen observed with increasing dc bias, namely we observe the oscillation maxima\ndevelop into minima and vice versa. Moreover, it is found that the onset\nbiasing current, at which a SdH extremum is about to invert, is linearly\ndependent on the magnetic field of the SdH extrema. These observations are\nquantitatively explained with the help of a general SdH formula.",
        "positive": "Fast-forward of adiabatic dynamics in quantum mechanics: We propose a way to accelerate adiabatic dynamics of wave functions in\nquantum mechanics to obtain a final adiabatic state except for the spatially\nuniform phase in any desired short time. We develop the previous theory of\nfast-forward (Masuda & Nakamura 2008) so as to derive a driving potential for\nthe fast-forward of the adiabatic dynamics. A typical example is the\nfast-forward of adiabatic transport of a wave function which is the ideal\ntransport in the sense that a stationary wave function is transported to an\naimed position in any desired short time without leaving any disturbance at the\nfinal time of the fast-forward. As other important examples we show accelerated\nmanipulations of wave functions such as their splitting and squeezing. The\ntheory is also applicable to macroscopic quantum mechanics described by the\nnonlinear Schroedinger equation."
    },
    {
        "anchor": "Light Trapping in Thin Film Disordered Nanohole Patterns: Effects of\n  Oblique Incidence and Intrinsic Absorption: Finite-difference time-domain method is employed to investigate the optical\nproperties of semiconductor thin films patterned with circular holes. The\npresence of holes enhances the coupling of the incident plane wave with the\nthin film and greatly enhances the absorption performance. For a typical 100 nm\nthin film, the optimal hole pattern is achieved when the hole radius is 180 nm\nand volume fraction is about $30\\%$. Disorderness can alter the absorption\nspectra and has an impact on the broadband absorption performance. The\nnon-uniform radius of holes can slightly broaden the absorption peaks and\nenhance the integrated absorption. Random hole position can completely change\nthe shape of the absorption spectra and the averaged integrated absorption\nefficiency is slightly smaller than the optimized ordered nanohole pattern.\nCompared to random positioned nanoholes or ordered nanohole, amorphous\narrangement of nanoholes will result in a much better absorption performance.\nHowever, it is also found that the absorption enhancement of amorphous pattern\nover an ordered pattern is weak when the incident angle departures from normal\nor when the intrinsic material absorption is strong.",
        "positive": "Quantum Tunneling of Magnetization in a Large Molecular Nanomagnet --\n  Approaching the Mesoscale: A Mn30 molecular cluster is established to be the largest single-molecule\nmagnet (SMM) discovered to date. Magnetization versus field measurements show\ncoercive fields of about 0.5 T at low temperatures. Magnetization decay\nexperiments reveal an Arrhenius behavior and temperature-independent relaxation\nbelow 0.2 K diagnostic of quantum tunneling of magnetization through the\nanisotropy barrier.The quantum hole digging method is used to establish\nresonant quantum tunneling. These results demonstrate that large molecular\nnanomagnets,having a volume of 15 nm^3, with dimensions approaching the\nmesoscale can still exhibit the quantum physics of the microscale."
    },
    {
        "anchor": "Realization of the square-root higher-order topological insulator in\n  electric circuits: Higher-order topological insulator (HOTI) represents a new phase of matter,\nthe characterization of which goes beyond the conventional bulk-boundary\ncorrespondence and is attracting significant attention by the broad community.\nUsing a square-root operation, it has been suggested that a square-root HOTI\nmay emerge in a hybrid honeycomb-kagome lattice. Here, we report the first\nexperimental realization of the square-root HOTI in topological LC circuits. We\nshow theoretically and experimentally that the square-root HOTI inherits the\nfeature of wave function from its parent, with corner states pinned to non-zero\nenergies. The topological feature is fully characterized by the bulk\npolarization. To directly measure the finite-energy corner modes, we introduce\nextra grounded inductors to each node. Our results experimentally substantiate\nthe emerging square-root HOTI and pave the way to realizing exotic topological\nphases that are challenging to observe in condensed matter physics.",
        "positive": "Non-Ergodicity & Microscopic Symmetry Breaking of the Conductance\n  Fluctuations in Disordered Mesoscopic Graphene: We show a dramatic deviation from ergodicity for the conductance fluctuations\nin graphene. In marked contrast to the ergodicity of dirty metals, fluctuations\ngenerated by varying magnetic field are shown to be much smaller than those\nobtained when sweeping Fermi energy. They also exhibit a strongly anisotropic\nresponse to the symmetry-breaking effects of a magnetic field, when applied\nperpendicular or parallel to the graphene plane. These results reveal a complex\npicture of quantum interference in graphene, whose description appears more\nchallenging than for conventional mesoscopic systems."
    },
    {
        "anchor": "Towards optimized surface $\u03b4$-profiles of nitrogen-vacancy centers\n  activated by helium irradiation in diamond: The negatively-charged nitrogen-vacancy (NV) center in diamond has been shown\nrecently as an excellent sensor for external spins. Nevertheless, their optimum\nengineering in the near-surface region still requires quantitative knowledge in\nregard to their activation by vacancy capture during thermal annealing. To this\naim, we report on the depth profiles of near-surface helium-induced NV centers\n(and related helium defects) by step-etching with nanometer resolution. This\nprovides insights into the efficiency of vacancy diffusion and recombination\npaths concurrent to the formation of NV centers. It was found that the range of\nefficient formation of NV centers is limited only to approximately $10$ to\n$15\\,$nm (radius) around the initial ion track of irradiating helium atoms.\nUsing this information we demonstrate the fabrication of nanometric-thin\n($\\delta$) profiles of NV centers for sensing external spins at the diamond\nsurface based on a three-step approach, which comprises (i) nitrogen-doped\nepitaxial CVD diamond overgrowth, (ii) activation of NV centers by low-energy\nhelium irradiation and thermal annealing, and (iii) controlled layer thinning\nby low-damage plasma etching. Spin coherence times (Hahn echo) ranging up to\n$50\\,$ $\\mu$s are demonstrated at depths of less than $5\\,$nm in material with\n$1.1\\,\\%$ of $^{13}$C (depth estimated by spin relaxation (T$_1$)\nmeasurements). At the end, the limits of the helium irradiation technique at\nhigh ion fluences are also experimentally investigated.",
        "positive": "Controllable nonreciprocal optical response and handedness-switching in\n  magnetized spin orbit coupled graphene: Starting from a low-energy effective Hamiltonian model, we theoretically\ncalculate the dynamical optical conductivity and permittivity tensor of a\nmagnetized graphene layer with Rashba spin orbit coupling (SOC). Our results\nreveal a transverse Hall conductivity correlated with the usual nonreciprocal\nlongitudinal conductivity. Further analysis illustrates that for intermediate\nmagnetization strengths, the relative magnitudes of the magnetization and SOC\ncan be identified experimentally by two well-separated peaks in the dynamical\noptical response (both the longitudinal and transverse components) as a\nfunction of photon frequency. Moreover, the frequency dependent permittivity\ntensor is obtained for a wide range of chemical potentials and magnetization\nstrengths. Employing experimentally realistic parameter values, we calculate\nthe circular dichroism of a representative device consisting of magnetized spin\norbit coupled graphene and a dielectric insulator layer, backed by a metallic\nplate. The results reveal that this device has different relative\nabsorptivities for right-handed and left-handed circularly polarized\nelectromagnetic waves. It is found that the magnetized spin orbit coupled\ngraphene supports strong handedness-switchings, effectively controlled by\nvarying the chemical potential and magnetization strength with respect to the\nSOC strength."
    },
    {
        "anchor": "Magneto-transport and Shubnikov-de Haas oscillations in the layered\n  ternary telluride Ta3SiTe6 topological semimetal: Topological semimetals characterize a novel class of quantum materials\nhosting Dirac/Weyl fermions. The important features of topological fermions can\nbe exhibited by quantum oscillations. Here we report the magnetoresistance and\nShubnikov-de Haas (SdH) quantum oscillation of longitudinal resistance in the\nsingle crystal of topological semimetal Ta3SiTe6 with the magnetic field up to\n38 T. Periodic amplitude of the oscillations reveals related information about\nthe Fermi surface. The fast Fourier transformation spectra represent a single\noscillatory frequency. The analysis of the oscillations shows the Fermi pocket\nwith a cross-section area of 0.13 angstrom power minus 2. Combining\nmagneto-transport measurements and the first-principles calculation, we find\nthat these oscillations come from the hole pocket. Hall resistivity and the SdH\noscillations recommend that Ta3SiTe6 is a hole dominated system.",
        "positive": "Enhanced nonlinear optical response from individual silicon nanowires: We report about the experimental observation and characterization of\nnonlinear optical properties of individual silicon nanowires of different\ndimensions. Our results show that the nonlinear light has different components,\none of them corresponding to the second harmonic generation (SHG). The SHG\nstrongly depends on the polarization of the optical excitation and nanowire\ndiameter, and gives access to the local electromagnetic field intensity\ndistribution. Furthermore, we show that the second harmonic, when observed, is\nenhanced compared to bulk silicon and is sensitive to optical resonances\nsupported by the nanowires. This offers different perspectives on the\ndefinition of silicon-based nonlinear photonic devices."
    },
    {
        "anchor": "A cavity-Cooper pair transistor scheme for investigating quantum\n  optomechanics in the ultra-strong coupling regime: We propose a scheme involving a Cooper pair transistor (CPT) embedded in a\nsuperconducting microwave cavity, where the CPT serves as a charge tunable\nquantum inductor to facilitate ultra-strong coupling between photons in the\ncavity and a nano- to meso-scale mechanical resonator. The mechanical resonator\nis capacitively coupled to the CPT, such that mechanical displacements of the\nresonator cause a shift in the CPT inductance and hence the cavity's resonant\nfrequency. The amplification provided by the CPT is sufficient for the zero\npoint motion of the mechanical resonator alone to cause a significant change in\nthe cavity resonance. Conversely, a single photon in the cavity causes a shift\nin the mechanical resonator position on the order of its zero point motion. As\na result, the cavity-Cooper pair transistor (cCPT) coupled to a mechanical\nresonator will be able to access a regime in which single photons can affect\nsingle phonons and vice versa. Realizing this ultra-strong coupling regime will\nfacilitate the creation of non-classical states of the mechanical resonator, as\nwell as the means to accurately characterize such states by measuring the\ncavity photon field.",
        "positive": "Radiative and phonon-induced dephasing in double quantum dots: A simple method for describing the evolution of a quantum state of a double\nquantum dot system interacting simultaneously with the electromagnetic\nenvironment and with the lattice modes is developed. It is shown that the joint\naction of the two reservoirs leads to nontrivial effects in the system\ndephasing. As an example, the impact of phonon-induced initial dephasing on the\nradiative decay of delocalized exciton states is discussed."
    },
    {
        "anchor": "Nonlinear screening and stopping power in two-dimensional electron gases: We have used density functional theory to study the nonlinear screening\nproperties of a two-dimensional (2D) electron gas. In particular, we consider\nthe screening of an external static point charge of magnitude Z as a function\nof the distance of the charge from the plane of the gas. The self-consistent\nscreening potentials are then used to determine the 2D stopping power in the\nlow velocity limit based on the momentum transfer cross-section. Calculations\nas a function of Z establish the limits of validity of linear and quadratic\nresponse theory calculations, and show that nonlinear screening theory already\nprovides significant corrections in the case of protons. In contrast to the 3D\nsituation, we find that the nonlinearly screened potential supports a bound\nstate even in the high density limit. This behaviour is elucidated with the\nderivation of a high density screening theorem which proves that the screening\ncharge can be calculated perturbatively in the high density limit for arbitrary\ndimensions. However, the theorem has particularly interesting implications in\n2D where, contrary to expectations, we find that perturbation theory remains\nvalid even when the perturbing potential supports bound states.",
        "positive": "Field-tunable interactions and frustration in underlayer-mediated\n  artificial spin ice: Artificial spin ice systems have opened experimental windows into a range of\nmodel magnetic systems through the control of interactions among nanomagnet\nmoments. This control has previously been enabled by altering the nanomagnet\nsize and the geometry of their placement. Here we demonstrate that the\ninteractions in artificial spin ice can be further controlled by including a\nsoft ferromagnetic underlayer below the moments. Such a substrate also breaks\nthe symmetry in the array when magnetized, introducing a directional component\nto the correlations. Using spatially resolved magneto-optical Kerr effect\nmicroscopy to image the demagnetized ground states, we show that the\ncorrelation of the demagnetized states depends on the direction of underlayer\nmagnetization. Further, the relative interaction strength of nearest and\nnext-nearest neighbors varies significantly with the array geometry. We exploit\nthis feature to induce frustration in an inherently unfrustrated square lattice\ngeometry, demonstrating new possibilities for effective geometries in two\ndimensional nanomagnetic systems."
    },
    {
        "anchor": "Backscattering off a driven Rashba impurity at the helical edge: The spin degree of freedom is crucial for both understanding and exploiting\nthe particular properties of the edges of two-dimensional topological\ninsulators. In the absence of superconductivity and magnetism, Rashba coupling\nis the most relevant single particle perturbation in this system. Since Rashba\ncoupling does not break time reversal symmetry, its influence on transport\nproperties is only visible if processes that do not conserve the single\nparticle energy are included. Paradigmatic examples of such processes are\nelectron-electron interactions and time dependent external drivings. We analyze\nthe effects of a periodically driven Rashba impurity at the helical edge, in\nthe presence of electron-electron interactions. Interactions are treated by\nmeans of bosonization and the backscattering current is computed perturbatively\nup to second order in the impurity strength. We show that the backscattering\ncurrent is non-monotonic in the driving frequency. This property is a\nfingerprint of the Rashba impurity, being absent in the case of a magnetic\nimpurity in the helical liquid. Moreover, the non-monotonic behaviour allows us\nto directly link the backscattering current to the Luttinger parameter $K$,\nencoding the strength of electron-electron interactions.",
        "positive": "Native point defects in CuIn$_{1-x}$Ga$_x$Se$_{2}$: hybrid density\n  functional calculations predict origin of p- and n-type conductivity: We have performed a first-principles study of the p- and n-type conductivity\nin CuIn$_{1-x}$Ga$_x$Se$_{2}$ due to native point defects, based on the HSE06\nhybrid functional. Band alignment shows that the band gap becomes larger with\n$x$ due to the increasing conduction band minimum, rendering it hard to\nestablish n-type conductivity in CuGaSe$_{2}$. From the defect formation\nenergies, we find that In/Ga$_{\\mathrm{Cu}}$ is a shallow donor, while\nV$_{\\mathrm{Cu}}$, V$_{\\mathrm{In}/\\mathrm{Ga}}$ and\nCu$_{\\mathrm{In}/\\mathrm{Ga}}$ act as shallow acceptors. Using total charge\nneutrality of ionized defects and intrinsic charge carriers to determine the\nFermi level, we show that under In-rich growth conditions In$_{\\mathrm{Cu}}$\ncauses strongly n-type conductivity in CuInSe$_{2}$. Under In-poor growth\nconditions the conductivity type in CuInSe$_{2}$ alters to p-type and\ncompensation of the acceptors by In$_{\\mathrm{Cu}}$ reduces, as observed in\nphotoluminescence experiments. In CuGaSe$_{2}$, the native acceptors pin the\nFermi level far away from the conduction band minimum, thus inhibiting n-type\nconductivity. On the other hand, CuGaSe$_{2}$ shows strong p-type conductivity\nunder a wide range of Ga-poor growth conditions. Maximal p-type conductivity in\nCuIn$_{1-x}$Ga$_x$Se$_{2}$ is reached under In/Ga-poor growth conditions, in\nagreement with charge concentration measurements on samples with In/Ga-poor\nstoichiometry, and is primarily due to the dominant acceptor\nCu$_{\\mathrm{In}/\\mathrm{Ga}}$."
    },
    {
        "anchor": "Spin-current-induced charge current: We show that the injection of a pure spin current (not accompanied by charge\ncurrent) into a ring can induce a circulating charge current in the ring,\nprovided that transport coefficients of the ring are spin-dependent and\ninhomogeneous. As an example, we consider a hybrid ferromagnet(F)-normal\nmetal(N) ring system and calculate the magnitude of the charge current induced\nby the pure spin current injection. This phenomenon may have relevance for\nspintronic applications.",
        "positive": "Magnetic miniband and magnetotransport property of a graphene\n  superlattice: The eigen energy and the conductivity of a graphene sheet subject to a\none-dimensional cosinusoidal potential and in the presence of a magnetic field\nare calculated. Such a graphene superlattice presents three distinct magnetic\nminiband structures as the magnetic field increases. They are, respectively,\nthe triply degenerate Landau level spectrum, the nondegenerate minibands with\nfinite dispersion and the same Landau level spectrum with the pristine\ngraphene. The ratio of the magnetic length to the period of the potential\nfunction is the characteristic quantity to determine the electronic structure\nof the superlattice. Corresponding to these distinct electronic structures, the\ndiagonal conductivity presents very strong anisotropy in the weak and moderate\nmagnetic field cases. But the predominant magnetotransport orientation changes\nfrom the transverse to the longitudinal direction of the superlattice. More\ninterestingly, in the weak magnetic field case, the superlattice exhibits\nhalf-integer quantum Hall effect, but with large jump between the Hall\nplateaux. Thus it is different from the one of the pristine graphene."
    },
    {
        "anchor": "Dirac cones reshaped by interaction effects in suspended graphene: We report measurements of the cyclotron mass in graphene for carrier\nconcentrations n varying over three orders of magnitude. In contrast to the\nsingle-particle picture, the real spectrum of graphene is profoundly nonlinear\nso that the Fermi velocity describing the spectral slope reaches ~3x10^6 m/s at\nn <10^10 cm^-2, three times the value commonly used for graphene. The observed\nchanges are attributed to electron-electron interaction that renormalizes the\nDirac spectrum because of weak screening. Our experiments also put an upper\nlimit of ~0.1 meV on the possible gap in graphene.",
        "positive": "Superior thermal conductivity in suspended bilayer hexagonal boron\n  nitride: We reported the basal-plane thermal conductivity in exfoliated bilayer\nhexagonal boron nitride h-BN that was measured using suspended prepatterned\nmicrostructures. The h-BN sample suitable for thermal measurements was\nfabricated by dry-transfer method, whose sample quality, due to less polymer\nresidues on surfaces, is believed to be superior to that of PMMA-mediated\nsamples. The measured room temperature thermal conductivity is around 484\nWm-1K-1(+141 Wm-1K-1/ -24 Wm-1K-1) which exceeds that in bulk h-BN, providing\nexperimental observation of the thickness-dependent thermal conductivity in\nsuspended few-layer h-BN."
    },
    {
        "anchor": "Theory of Umklapp-assisted recombination of bound excitons in Si:P: We present the calculations for the oscillator strength of the recombination\nof excitons bound to phosphorous donors in silicon. We show that the direct\nrecombination of the bound exciton cannot account for the experimentally\nmeasured oscillator strength of the no-phonon line. Instead, the recombination\nprocess is assisted by an umklapp process of the donor electron state. We make\nuse of the empirical pseudopotential method to evaluate the Umklapp-assisted\nrecombination matrix element in second-order perturbation theory. Our result is\nin excellent agreement with the experiment. We also present two methods to\nimprove the optical resolution of the optical detection of the spin state of a\nsingle nucleus in silicon.",
        "positive": "Spin-orbit induced equilibrium spin currents in materials: The existence of spin-currents in absence of any driving external fields is\ncommonly considered an exotic phenomenon appearing only in quantum materials,\nsuch as topological insulators. We demonstrate instead that equilibrium spin\ncurrents are a rather general property of materials with non negligible\nspin-orbit coupling (SOC). Equilibrium spin currents can be present at the\nsurfaces of a slab. Yet, we also propose the existence of global equilibrium\nspin currents, which are net bulk spin-currents along specific crystallographic\ndirections of materials. Equilibrium spin currents are allowed by symmetry in a\nvery broad class of systems having gyrotropic point groups. The physics behind\nequilibrium spin currents is uncovered by making an analogy between electronic\nsystems with SOC and non-Abelian gauge theories. The electron spin can be seen\nas the analogous of the color degree of freedom and equilibrium spin currents\ncan then be identified with diamagnetic color currents appearing as the\nresponse to an effective non-Abelian magnetic field generated by SOC.\nEquilibrium spin currents are not associated with spin transport and\naccumulation, but they should nonetheless be carefully taken into account when\ncomputing transport spin currents. We provide quantitative estimates of\nequilibrium spin currents for several systems, specifically metallic surfaces\npresenting Rashba-like surface states, nitride semiconducting nanostructures\nand bulk materials, such as the prototypical gyrotropic medium tellurium. In\ndoing so, we also point out the limitations of model approaches showing that\nfirst-principles calculations are needed to obtain reliable predictions. We\ntherefore use Density Functional Theory computing the so-called bond currents,\nwhich represent a powerful tool to understand the relation between equilibrium\ncurrents, electronic structure and crystal point group."
    },
    {
        "anchor": "Transport properties of annealed CdSe nanocrystal solids: Transport properties of artificial solids composed of colloidal CdSe\nnanocrystals (NCs) are studied from 6 K to 250 K, before and after annealing.\nAnnealing results in greatly enhanced dark and photocurrent in NC solids, while\ntransmission electron microscopy (TEM) micrographs show that the inter-dot\nseparation decreases. The increased current can be attributed to the\nenhancement of inter-dot tunneling caused by the decreased separation between\nNCs and by chemical changes in their organic cap. In addition, the absorption\nspectra of annealed solids are slightly red-shifted and broadened. These\nred-shifts may result from the change of the dielectric environment around the\nNCs. Our measurements also indicate that Coulomb interactions between charges\non neighboring NCs play an important role in the tunneling current.",
        "positive": "Interlayer Dzyaloshinskii-Moriya interactions: Interfacial Dzyaloshinkii-Moriya interaction defines a rotational sense for\nthe magnetization of two-dimensional films making it responsible for the\nformation of chiral magnetic structures like spin-spirals and skyrmions in\nthose films. Here we show by means of atomistic calculations that in\nheterostructures magnetic layers can be additionally coupled by an interlayer\nDzyaloshinskii-Moriya interaction across a spacer. We quantify this interaction\nin the framework of the Levy-Fert model for trilayers consisting of two\nferromagnets separated by a non-magnetic spacer yielding non-trivial\nthree-dimensional spiral states across the trilayer. This analysis enables\nthree-dimensional tailoring of the magnetization chirality in magnetic\nmultilayers."
    },
    {
        "anchor": "Conversion rules for Weyl points and nodal lines in topological media: According to a widely-held paradigm, a pair of Weyl points with opposite\nchirality mutually annihilate when brought together. In contrast, we show that\nsuch a process is strictly forbidden for Weyl points related by a mirror\nsymmetry, provided that an effective two-band description exists in terms of\norbitals with opposite mirror eigenvalue. Instead, such a pair of Weyl points\nconvert into a nodal loop inside a symmetric plane upon the collision. Similar\nconstraints are identified for systems with multiple mirrors, facilitating\npreviously unreported nodal-line and nodal-chain semimetals that exhibit both\nFermi-arc and drumhead surface states. We further find that Weyl points in\nsystems symmetric under a $\\pi$-rotation composed with time-reversal are\ncharacterized by an additional integer charge that we call helicity. A pair of\nWeyl points with opposite chirality can annihilate only if their helicities\nalso cancel out. We base our predictions on topological crystalline invariants\nderived from relative homotopy theory, and we test our predictions on simple\ntight-binding models. The outlined homotopy description can be directly\ngeneralized to systems with multiple bands and other choices of symmetry.",
        "positive": "Indirect spin dephasing via charge state decoherence in optical control\n  schemes in quantum dots: We demonstrate that an optically driven spin of a carrier in a quantum dot\nundergoes indirect dephasing via conditional optically induced charge evolution\neven in the absence of any direct interaction between the spin and its\nenvironment. A generic model for the indirect dephasing with a three-component\nsystem with spin, charge, and reservoir is proposed. This indirect decoherence\nchannel is studied for the optical spin manipulation in a quantum dot with a\nmicroscopic description of the charge-phonon interaction taking into account\nits non-Markovian nature."
    },
    {
        "anchor": "Geometric density of states of electronic structures for local\n  responses: Phase information from the amplitudes of STM measurement: Electronic band structures underlie the physical properties of crystalline\nmaterials, their geometrical exploration renovates the conventional cognition\nand brings about novel applications. Inspired by geometry phases, we introduce\na geometric amplitude named as the geometric density of states (GDOS) dictated\nby the differential curvature of the constant-energy contour. The GDOS\ndetermines the amplitude of the real-space Green's function making it attain\nthe ultimate expression with transparent physics. The local responses of\ncrystalline materials are usually formulated by the real-space Green's\nfunction, so the relevant physics should be refreshed by GDOS. As an example of\nlocal responses, we suggest using scanning tunneling microscopy (STM) to\ncharacterize the surface states of three-dimensional topological insulator\nunder an in-plane magnetic field. The GDOS favors the straightforward\nsimulation of STM measurement without resorting to Fourier transform of the\nreal-space measurement, and also excavates the unexplored potential of STM\nmeasurement to extract the phase information of wavefunction through its\namplitude, i.e., the spin and curvature textures. Therefore, the proposed GDOS\ndeepens the understanding of electronic band structures and is indispensable in\nlocal responses, and it should be universal for any periodic systems.",
        "positive": "Flat and safe under the graphene sheet: Large-scale atomically thin metals can be stabilized through confinement\nepitaxy at graphene / SiC interface, which exhibit a gradient bonding type and\nare air stable, providing a compelling platform for quantum and optoelectronic\ntechnologies."
    },
    {
        "anchor": "Exceptional degeneracies in non-Hermitian Rashba semiconductors: Exceptional points are spectral degeneracies of non-Hermitian systems where\neigenvalues and eigenvectors coalesce, inducing unique topological phases that\nhave no counterpart in the Hermitian realm. Here we consider a non-Hermitian\nsystem by coupling a two-dimensional semiconductor with Rashba spin-orbit\ncoupling to a ferromagnet lead and show the emergence of highly tunable\nexceptional points along rings in momentum space. Interestingly, these\nexceptional degeneracies are the endpoints of lines formed by the eigenvalue\ncoalescence at finite real energy, resembling the bulk Fermi arcs commonly\ndefined at zero real energy. We then show that an in-plane Zeeman field\nprovides a way to control these exceptional degeneracies although higher values\nof non-Hermiticity are required in contrast to the zero Zeeman field regime.\nFurthermore, we find that the spin projections also coalescence at the\nexceptional degeneracies and can acquire larger values than in the Hermitian\nregime. Finally, we demonstrate that the exceptional degeneracies induce large\nspectral weights, which can be used as a signature for their detection. Our\nresults thus reveal the potential of systems with Rashba spin-orbit coupling\nfor realizing non-Hermitian bulk phenomena.",
        "positive": "Effect of dipolar interactions on optical nonlinearity of\n  two-dimensional nanocomposites: In this work, we calculate the contribution of dipole-dipole interactions to\nthe optical nonlinearity of the two-dimensional random ensemble of\nnanoparticles that possess a set of exciton levels, for example, quantum dots.\nThe analytical expressions for the contributions in the cases of TM and\nTE-polarized light waves propagating along the plane are obtained. It is shown\nthat the optical nonlinearity, caused by the dipole-dipole interactions in the\nplanar ensemble of the nanoparticles, is several times smaller than the similar\nnonlinearity of the bulk nanocomposite. This type of optical nonlinearity is\nexpected to be observed at timescales much larger than the quantum dot exciton\nrise time. The proposed method may be applied to various types of the\nnanocomposite shapes."
    },
    {
        "anchor": "Electron Pair Resonance in the Coulomb Blockade: We study many-body corrections to the cotunneling current via a localized\nstate with energy $\\epsilon_d$ at large bias voltages $V$. We show that the\ntransfer of {\\em electron pairs}, enabled by the Coulomb repulsion in the\nlocalized level, results in ionization resonance peaks in the third derivative\nof the current with respect to $V$, centered at $eV=\\pm 2\\epsilon_d/3$. Our\nresults predict the existence of previously unnoticed structure within\nCoulomb-blockade diamonds.",
        "positive": "Highly-sensitive superconducting quantum interference proximity\n  transistor: We report the design and implementation of a high-performance superconducting\nquantum interference proximity transistor (SQUIPT) based on aluminum-copper\n(Al-Cu) technology. With the adoption of a thin and short copper nanowire we\ndemostrate full phase-driven modulation of the proximity-induced minigap in the\nnormal metal density of states. Under optimal bias we record unprecedently high\nflux-to-voltage (up to 3 mV/$\\Phi_0$) and flux-to-current (exceeding 100\nnA/$\\Phi_0$) transfer function values at sub-Kelvin temperatures, where\n$\\Phi_0$ is the flux quantum. The best magnetic flux resolution (as low as 500\nn$\\Phi_0/\\sqrt{Hz}$ at 240 mK, being limited by the room temperature\npre-amplification stage) is reached under fixed current bias. These figures of\nmerit combined with ultra-low power dissipation and micrometer-size dimensions\nmake this mesoscopic interferometer attractive for low-temperature applications\nsuch as the investigation of the magnetization of small spin populations."
    },
    {
        "anchor": "Selective spin transport through a quantum heterostructure: Transfer\n  matrix method: In the present work we propose that a one-dimensional quantum heterostructure\ncomposed of magnetic and non-magnetic atomic sites can be utilized as a spin\nfilter for a wide range of applied bias voltage. A simple tight-binding\nframework is given to describe the conducting junction where the\nheterostructure is coupled to two semi-infinite one-dimensional non-magnetic\nelectrodes. Based on transfer matrix method all the calculations are performed\nnumerically which describe two-terminal spin dependent transmission probability\nalong with junction current through the wire. Our detailed analysis may provide\nfundamental aspects of selective spin transport phenomena in one-dimensional\nheterostructures at nano-scale level.",
        "positive": "Theory and design of quantum light sources from quantum dots embedded in\n  semiconductor-nanowire photonic crystal systems: We introduce a new platform for realizing on-chip quantum electrodynamics\nusing photonic crystal waveguide structures comprised of periodic nanowire\narrays with embedded semiconductor quantum dots to act as quantum light\nsources. These nanowire-based structures, which can now be fabricated with\nexcellent precision, are found to produce waveguide Purcell factors exceeding\n100 and on-chip beta factors up to 99%. We investigate the fundamental optical\nproperties of photonic crystal waveguides and finite-size structures using both\nphotonic band structure calculations and rigorous Green function computations\nwhich allows us to obtain the modal properties and the local density of photon\nstates. A comparison with slab-based photonic crystals is also made and we a\nhighlight key advantages in the nanowire system, including the potential to\nminimize extrinsic scattering losses and produce high theoretical Purcell\nfactors and beta-factors on-chip. We also demonstrate that these structures\nexhibit rich photonic Lamb shifts over broadband frequencies."
    },
    {
        "anchor": "Brownian thermal transistors and refrigerators in mesoscopic systems: Fluctuations are significant in mesoscopic systems and of particular\nimportance in understanding quantum transport. Here, we show that fluctuations\ncan be considered as a resource for the operations of open quantum systems as\nfunctional devices. We derive the statistics of the thermal transistor\namplification factor and the cooling-by-heating refrigerator efficiency under\nthe Gaussian fluctuation framework. Statistical properties of the stochastic\nthermal transistor and the cooling-by-heating efficiency are revealed in the\nlinear-response regime. We clarify the unique role of inelastic processes on\nthermal transport in mesoscopic systems. We further show that elastic and\ninelastic processes lead to different bounds based on the linear transport\ncoefficients by establishing a generic theoretical framework for mesoscopic\nheat transport, which treats electron and bosonic collective excitations in an\nequal-footing manner. The underlying physics are illustrated concretely using a\ndouble-quantum-dot three-terminal system, though the theory applies to more\ngeneral systems.",
        "positive": "Laser-induced persistent photovoltage on the surface of a ternary\n  topological insulator at room temperature: Using time- and angle-resolved photoemission, we investigate the ultrafast\nresponse of excited electrons in the ternary topological insulator (Bi$_{1\nx}$Sb$_{x}$)$_2$Te$_3$ to fs-infrared pulses. We demonstrate that at the\ncritical concentration $x$=0.55, where the system becomes bulk insulating, a\nsurface voltage can be driven at room temperature through the topological\nsurface state solely by optical means. We further show that such a photovoltage\npersists over a time scale that exceeds $\\sim$6 $\\mu$s, i.e, much longer than\nthe characteristic relaxation times of bulk states. We attribute the origin of\nthe photovoltage to a laser-induced band-bending effect which emerges near the\nsurface region on ultrafast time scales. The photovoltage is also accompanied\nby a remarkable increase in the relaxation times of excited states as compared\nto undoped topological insulators. Our findings are relevant in the context of\napplications of topological surface states in future optical devices."
    },
    {
        "anchor": "Kondo Problems in Tomonaga-Luttinger liquids: Quantum impurity problems in Tomonaga-Luttinger liquids (TLLs) are reviewed\nwith emphasis on their analogy to the Kondo problem in Fermi liquids. First,\nthe problem of a static impurity in a spinless TLL is considered, which is\nrelated to the model studied in the context of the macroscopic quantum\ncoherence. In the low-energy limit the TLL is essentially cut into two pieces\nwhen interaction is repulsive. The orthogonality catastrophe in a TLL is then\ndiscussed. Finally, the Kondo effect of a spin-1/2 impurity in a\none-dimensional repulsively interacting electron liquids (a spinful TLL) is\nreviewed. Regardless of the sign of the exchange coupling, the impury spin is\ncompletely screened in the ground state. The leading low-temperature\ncontributions to thermodynamic quantities come from boundary contributions of a\nbulk leading irrelevant operator.",
        "positive": "Thermoelectric Generation of Orbital Magnetization in Metals: We propose an orbital magnetothermal effect wherein a temperature gradient\ngenerates an orbital magnetization (OM) for Bloch electrons, and we present a\nunified theory for electrically and thermally induced OM, valid for both metals\nand insulators. We reveal that there exists an intrinsic response of OM, for\nwhich the susceptibilities are completely determined by the band geometric\nquantities such as interband Berry connections, interband orbital moments, and\nthe quantum metric. The theory can be readily combined with first-principles\ncalculations to study real materials. As an example, we calculate the OM\nresponse in CrI$_{3}$ bilayers, where the intrinsic contribution dominates. The\ntemperature scaling of intrinsic and extrinsic responses, the effect of phonon\ndrag, and the phonon angular momentum contribution to OM are discussed."
    },
    {
        "anchor": "Quantum Theory of Heat Magnetization: We give the thermodynamic definition of the heat magnetization, and calculate\nwith use of the Keldysh formalism in a curved spacetime. The heat magnetization\nis conjugate to a torsional magnetic field, which is analogous to the fact that\nthe orbital magnetization is conjugate to a magnetic field. The formula is\nvalid in insulators and metals at finite temperature even in disordered or\ninteracting systems.",
        "positive": "An Exact Expression for Multidimensional Spectroscopy of a Spin-Boson\n  Hamiltonian: Multidimensional coherent spectroscopy is a powerful tool to characterize\nnonlinear optical response functions. Typically, multidimensional spectra are\ninterpreted via a perturbative framework that straightforwardly provides\nintuition into the density matrix dynamics that give rise to specific spectral\nfeatures. When the goal is to characterize system coupling to a thermal bath\nhowever, the perturbative formalism becomes unwieldy and yields less intuition.\nHere, we extend an approach developed by Vagov et al. to provide an exact\nexpression for multidimensional spectra of a spin-boson Hamiltonian up to\narbitrary order of electric field interaction. We demonstrate the utility of\nthis expression by modeling polaron formation and coherent exciton-phonon\ncoupling in quantum dots, which strongly agree with experiment."
    },
    {
        "anchor": "Interactions-disorder duality and critical phenomena in nodal\n  semimetals, dilute gases and other systems: We investigate classes of interacting systems that allow for a mapping to\ndisordered noninteracting systems. As we show, such a mapping is possible for\ninteracting systems with a suppressed density of states at the chemical\npotential, leading to suppressed screening, and systems near BCS-type\ninstabilities. The mapping can also be applied qualitatively to other classes\nof systems that are not exactly dual to each other. The established duality\nsuggests a new approach to analytical and numerical studies of many-body and\ndisorder-driven phenomena in a variety of systems and allows to predict, e.g.,\nnew phase transitions dual to the previously known ones. Using the established\nduality, we predict new disorder-driven transitions in nodal-line semimetals\nand systems with long-range hopping dual to, respectively, the BCS and\nBEC-vacuum transitions in interacting systems and new interaction-driven\ntransitions dual to previously known non-Anderson disorder-driven transitions.\nThe established principle can also be used to classify and describe phase\ntransitions in dissipative systems described by non-Hermitian Hamiltonians.",
        "positive": "Giant-spin nonlinear response theory of magnetic nanoparticle\n  hyperthermia: a field dependence study: Understanding high-field amplitude electromagnetic heat loss phenomena is of\ngreat importance, in particular in the biomedical field, since the\nheat-delivery treatment plans might rely on analytical models that are only\nvalid at low field amplitudes. Here, we develop a nonlinear response model\nvalid for single- domain nanoparticles of larger particle sizes and higher\nfield amplitudes in comparison to linear response theory. A nonlinear\nmagnetization expression and a generalized heat loss power equation are\nobtained and compared with the exact solution of the stochastic\nLandau-Lifshitz-Gilbert equation assuming the giant-spin hypothesis. The model\nis valid within the hyperthermia therapeutic window and predicts a shift of\noptimum particle size and distinct heat loss field amplitude exponents.\nExperimental hyperthermia data with distinct ferrite-based nanoparticles, as\nwell as third harmonic magnetization data supports the nonlinear model, which\nalso has implications for magnetic particle imaging and magnetic thermometry."
    },
    {
        "anchor": "Quantum pump driven fermionic Mach-Zehnder interferometer: We have investigated the characteristics of the currents in a pump-driven\nfermionic Mach-Zehnder interferometer. The system is implemented in a conductor\nin the quantum Hall regime, with the two interferometer arms enclosing an\nAharonov-Bohm flux $\\Phi$. Two quantum point contacts with transparency\nmodulated periodically in time drive the current and act as beam-splitters. The\ncurrent has a flux dependent part $I^{(\\Phi)}$ as well as a flux independent\npart $I^{(0)}$. Both current parts show oscillations as a function of frequency\non the two scales determined by the lengths of the interferometer arms. In the\nnon-adiabatic, high frequency regime $I^{(\\Phi)}$ oscillates with a constant\namplitude while the amplitude of the oscillations of $I^{(0)}$ increases\nlinearly with frequency. The flux independent part $I^{(0)}$ is insensitive to\ntemperature while the flux dependent part $I^{(\\Phi)}$ is exponentially\nsuppressed with increasing temperature. We also find that for low amplitude,\nadiabatic pumping rectification effects are absent for semitransparent\nbeam-splitters. Inelastic dephasing is introduced by coupling one of the\ninterferometer arms to a voltage probe. For a long charge relaxation time of\nthe voltage probe, giving a constant probe potential, $I^{(\\Phi)}$ and the part\nof $I^{(0)}$ flowing in the arm connected to the probe are suppressed with\nincreased coupling to the probe. For a short relaxation time, with the\npotential of the probe adjusting instantaneously to give zero time dependent\ncurrent at the probe, only $I^{(\\Phi)}$ is suppressed by the coupling to the\nprobe.",
        "positive": "Topological phase transitions and Berry-phase hysteresis in\n  exchange-coupled nanomagnets: Topological phase in magnetic materials yields a quantized contribution to\nthe Hall effect known as the topological Hall effect, which is often caused by\nskyrmions, with each skyrmion creating a magnetic flux quantum h/e. The control\nand understanding of topological properties in nanostructured materials is the\nsubject of immense interest for both fundamental science and technological\napplications, especially in spintronics. In this work, the electron-transport\nproperties and spin structure of exchange-coupled cobalt nanoparticles with an\naverage particle size of 13.7 nm are studied experimentally and theoretically.\nMagnetic and Hall-effect measurements identify topological phase transitions in\nthe exchange-coupled cobalt nanoparticles and were used to discover a\nqualitatively new type of hysteresis in the topological Hall effect namely,\nBerry-phase hysteresis. Micromagnetic simulations reveal the origin of the\ntopological Hall effect namely, the chiral domains, with domain-wall chirality\nquantified by an integer skyrmion number. These spin structures are different\nfrom the skyrmions formed due to Dzyaloshinskii Moriya interactions in B20\ncrystals and multilayered thin films, and caused by cooperative magnetization\nreversal in the exchange-coupled cobalt nanoparticles. An analytical model is\ndeveloped to explain the underlying physics of Berry-phase hysteresis, which is\nstrikingly different from the iconic magnetic hysteresis and constitutes one\naspect of 21st-century reshaping of our view on nature at the borderline of\nphysics, chemistry, mathematics, and materials science."
    },
    {
        "anchor": "Ground-state energy and spin in disordered quantum dots: We investigate the ground-state energy and spin of disordered quantum dots\nusing spin-density-functional theory. Fluctuations of addition energies\n(Coulomb-blockade peak spacings) do not scale with average addition energy but\nremain proportional to level spacing. With increasing interaction strength, the\neven-odd alternation of addition energies disappears, and the probability of\nnon-minimal spin increases, but never exceeds 50%. Within a two-orbital model,\nwe show that the off-diagonal Coulomb matrix elements help stabilize a ground\nstate of minimal spin.",
        "positive": "Tunable edge magnetism at graphene/graphane interfaces: We study the magnetic properties of graphene edges and graphene/graphane\ninterfaces under the influence of electrostatic gates. For this, an effective\nlow-energy theory for the edge states, which is derived from the Hubbard model\nof the honeycomb lattice, is used. We first study the edge state model in a\nmean-field approximation for the Hubbard Hamiltonian and show that it\nreproduces the results of the extended 2D lattice theory. Quantum fluctuations\naround the mean-field theory of the effective one-dimensional model are treated\nby means of the bosonization technique in order to check the stability of the\nmean-field solution. We find that edge magnetism at graphene/graphane\ninterfaces can be switched on and off by means of electrostatic gates. We\ndescribe a quantum phase transition between an ordinary and a ferromagnetic\nLuttinger liquid - a realization of itinerant one-dimensional ferromagnetism.\nThis mechanism may provide means to experimentally discriminate between edge\nmagnetism or disorder as the reason for a transport gap in very clean graphene\nnanoribbons."
    },
    {
        "anchor": "Optical conductivity of an interacting Weyl liquid in the collisionless\n  regime: Optical conductivity (OC) can serve as a measure of correlation effects in a\nwide range of condensed matter systems. We here show that the long-range tail\nof the Coulomb interaction yields a universal correction to the OC in a\nthree-dimensional Weyl semimetal $\\sigma(\\Omega)=\\sigma_0(\\Omega)\\left[\n1+\\frac{1}{N+1} \\right]$, where of $\\sigma_0(\\Omega)=Ne^2_0 \\Omega/(12 h v)$ is\nthe OC in the non-interacting system, with $v$ as the actual (renormalized)\nFermi velocity of Weyl quasiparticles at frequency $\\Omega$, and $e_0$ is the\nelectron charge in vacuum. Such universal enhancement of OC, which depends only\non the number of Weyl nodes near the Fermi level ($N$), is a remarkable\nconsequence of an intriguing conspiracy among the quantum-critical nature of an\ninteracting Weyl liquid, marginal irrelevance of the long-range Coulomb\ninteraction and the violation of hyperscaling in three dimensions, and can\ndirectly be measured in recently discovered Weyl as well as Dirac materials. By\ncontrast, a local density-density interaction produces a non-universal\ncorrection to the OC, stemming from the non-renormalizable nature of the\ncorresponding interacting field theory.",
        "positive": "Wavevector-dependent spin filtering and spin transport through magnetic\n  barriers in graphene: We study the spin-resolved transport through magnetic nanostructures in\nmonolayer and bilayer graphene. We take into account both the orbital effect of\nthe inhomogeneous perpendicular magnetic field as well as the in-plane spin\nsplitting due to the Zeeman interaction and to the exchange coupling possibly\ninduced by the proximity of a ferromagnetic insulator. We find that a single\nbarrier exhibits a wavevector-dependent spin filtering effect at energies close\nto the transmission threshold. This effect is significantly enhanced in a\nresonant double barrier configuration, where the spin polarization of the\noutgoing current can be increased up to 100% by increasing the distance between\nthe barriers."
    },
    {
        "anchor": "Ultra-Efficient Coupling of a Quantum Emitter to the Tunable Guided\n  Plasmons of a Carbon Nanotube: We show that a single quantum emitter can efficiently couple to the tunable\nplasmons of a highly doped single-wall carbon nanotube (SWCNT). Plasmons in\nthese quasi-one-dimensional carbon structures exhibit deep subwavelength\nconfinement that pushes the coupling efficiency close to 100% over a very broad\nspectral range. This phenomenon takes place for distances and tube diameters\ncomprising the nanometer and micrometer scales. In particular, we find a beta\nfactor ~1 for QEs placed 1-100 nm away from SWCNTs that are just a few\nnanometers in diameter, while the corresponding Purcell factor exceeds 10^6.\nOur finding not only holds great potential for waveguide QED, in which an\nefficient interaction between emitters and cavity modes is pivotal, but it also\nprovides a way of realizing quantum strong coupling between several emitters\nmediated by SWCNT plasmons, which can be controlled through the large\nelectro-optical tunability of these excitations.",
        "positive": "Studying many-body localization in exchange-coupled electron spin qubits\n  using spin-spin correlations: We show that many-body localization (MBL) effects can be observed in a finite\nchain of exchange-coupled spin qubits in the presence of both exchange and\nmagnetic noise, a system that has been experimentally realized in\nsemiconductors and is a potential solid-state quantum computing platform. In\naddition to established measures of MBL, the level spacing ratio and the\nentanglement entropy, we propose another quantity, the spin-spin correlation\nfunction, that can be measured experimentally and is particularly well-suited\nto experiments in semiconductor-based electron spin qubit systems. We show\nthat, in cases that the established measures detect as delocalized \"phases\",\nthe spin-spin correlation functions retain no memory of the system's initial\nstate (i.e., the long-time value deviates significantly from the initial\nvalue), but that they do retain memory in cases that the established measures\ndetect as localized \"phases\". We also discover an interesting counterintuitive\nresult that there is no clear tendency towards localization with increasing\ncharge noise in small systems ($3$--$10$ spins). The proposed experiments\nshould be feasible in the existing semiconductor spin qubit systems."
    },
    {
        "anchor": "Counterpropagating topological and quantum Hall edge channels: The survival of the quantum spin Hall edge channels in presence of an\nexternal magnetic field has been a subject of experimental and theoretical\nresearch. The inversion of Landau levels that accommodates the quantum spin\nHall effect is destroyed at a critical magnetic field, and a trivial insulating\ngap appears in the spectrum for stronger fields. In this work, we report the\nabsence of this transport gap in disordered two dimensional topological\ninsulators in perpendicular magnetic fields of up to 16 T. Instead, we observe\nthat a topological edge channel (from band inversion) coexists with a\ncounterpropagating quantum Hall edge channel for magnetic fields at which the\ntransition to the insulating regime is expected. For larger fields, we observe\nonly the quantum Hall edge channel with transverse resistance close to $h/e^2$.\nBy tuning the disorder using different fabrication processes, we find evidence\nthat this unexpected $\\nu=1$ plateau originates from extended quantum Hall edge\nchannels along a continuous network of charge puddles at the edges of the\ndevice.",
        "positive": "Manipulation of polarization and spatial properties of light beams with\n  chiral metafilms: Two-dimensional lattices of chiral nanoholes in a plasmonic film with lattice\nconstants being slightly larger than light wavelength are proposed for\neffective control of polarization and spatial properties of light beams.\nEffective polarization conversion and strong circular dichroism in non-zero\ndiffraction orders in these chiral metafilms are demonstrated by\nelectromagnetic simulations. These interesting effects are found to result from\ninterplay between radiation pattern of single chiral nanohole and diffraction\npattern of the planar lattice, and can be manipulated by varying wavelength and\npolarization of incoming light as well as period of metastructure and\nrefractive indexes of substrate and overlayer. Therefore, this work offers a\nnovel paradigm for developing planar chiral metafilm-based optical devices with\ncontrollable polarization state, spatial orientation and intensity of outgoing\nlight."
    },
    {
        "anchor": "Magnetization profile for impurities in graphene nanoribbons: The magnetic properties of graphene-related materials and in particular the\nspin-polarised edge states predicted for pristine graphene nanoribbons (GNRs)\nwith certain edge geometries have received much attention recently due to a\nrange of possible technological applications. However, the magnetic properties\nof pristine GNRs are not predicted to be particularly robust in the presence of\nedge disorder. In this work, we examine the magnetic properties of GNRs doped\nwith transition-metal atoms using a combination of mean-field Hubbard and\nDensity Functional Theory techniques. The effect of impurity location on the\nmagnetic moment of such dopants in GNRs is investigated for the two principal\nGNR edge geometries - armchair and zigzag. Moment profiles are calculated\nacross the width of the ribbon for both substitutional and adsorbed impurities\nand regular features are observed for zigzag-edged GNRs in particular. Unlike\nthe case of edge-state induced magnetisation, the moments of magnetic\nimpurities embedded in GNRs are found to be particularly stable in the presence\nof edge disorder. Our results suggest that the magnetic properties of\ntransition-metal doped GNRs are far more robust than those with moments arising\nintrinsically due to edge geometry.",
        "positive": "Bulk--Boundary Correspondence for Chiral Symmetric Quantum Walks: Discrete-time quantum walks (DTQW) have topological phases that are richer\nthan those of time-independent lattice Hamiltonians. Even the basic symmetries,\non which the standard classification of topological insulators hinges, have not\nyet been properly defined for quantum walks. We introduce the key tool of\ntimeframes, i.e., we describe a DTQW by the ensemble of time-shifted unitary\ntimestep operators belonging to the walk. This gives us a way to consistently\ndefine chiral symmetry (CS) for DTQW's. We show that CS can be ensured by using\nan \"inversion symmetric\" pulse sequence. For one-dimensional DTQW's with CS, we\nidentify the bulk ZxZ topological invariant that controls the number of\ntopologically protected 0 and pi energy edge states at the interfaces between\ndifferent domains, and give simple formulas for these invariants. We illustrate\nthis bulk--boundary correspondence for DTQW's on the example of the \"4-step\nquantum walk\", where tuning CS and particle-hole symmetry realizes edge states\nin various symmetry classes."
    },
    {
        "anchor": "Thermalization of dipole oscillations in confined systems by rare\n  collisions: We study the relaxation of the center-of-mass, or dipole oscillations in the\nsystem of interacting fermions confined spatially. With the confinement\nfrequency $\\omega_{\\perp}$ fixed the particles were considered to freely move\nalong one (quasi-1D) or two (quasi-2D) spatial dimensions. We have focused on\nthe regime of rare collisions, such that the inelastic collision rate,\n$1/\\tau_{in} \\ll \\omega_{\\perp}$. The dipole oscillations relaxation rate,\n$1/\\tau_{\\perp}$ is obtained at three different levels: by direct perturbation\ntheory, solving the integral Bethe-Salpeter equation and applying the memory\nfunction formalism. As long as anharmonicity is weak, $1/\\tau_{\\perp} \\ll 1/\n\\tau_{in}$ the three methods are shown to give identical results. In quasi-2D\ncase $1/\\tau_{\\perp} \\neq 0$ at zero temperature. In quasi-1D system\n$1/\\tau_{\\perp} \\propto T^3$ if the Fermi energy, $E_F$ lies below the critical\nvalue, $E_F < 3 \\omega_{\\perp}/4$. Otherwise, unless the system is close to\nintegrability, the rate $1/\\tau_{\\perp}$ has the temperature dependence similar\nto that in quasi-2D. In all cases the relaxation results from the excitation of\nparticle-hole pairs propagating along unconfined directions resulting in the\nrelationship $1/\\tau_{\\perp} \\propto 1/\\tau_{in}$, with the inelastic rate\n$1/\\tau_{in} \\neq 0$ as the phase-space opens up at finite energy of\nexcitation, $\\hbar \\omega_{\\perp}$. While $1/\\tau_{\\perp} \\propto \\tau_{in}$ in\nthe hydrodynamic regime, $\\omega_{\\perp} \\ll 1/\\tau_{in}$, in the regime of\nrare collisions, $\\omega_{\\perp} \\gg 1/\\tau_{in}$, we obtain the opposite trend\n$1/\\tau_{\\perp} \\propto 1/\\tau_{in}$.",
        "positive": "Near-field radiative heat transfer between a sphere and a substrate: Near-field force and energy exchange between two objects due to quantum\nelectrodynamic fluctuations give rise to interesting phenomena such as Casimir\nand van der Waals forces, and thermal radiative transfer exceeding Planck's\ntheory of blackbody radiation. Although significant progress has been made in\nthe past on the precise measurement of Casimir force related to zero-point\nenergy, experimental demonstration of near-field enhancement of radiative heat\ntransfer is difficult. In this work, we present a sensitive technique of\nmeasuring near-field radiative transfer between a microsphere and a substrate\nusing a bi-material atomic force microscope (AFM) cantilever, resulting in\n\"heat transfer-distance\" curves. Measurements of radiative transfer between a\nsphere and a flat substrate show the presence of strong near-field effects\nresulting in enhancement of heat transfer over the predictions of the Planck\nblackbody radiation theory."
    },
    {
        "anchor": "On-Chip Cooling by Heating with Superconducting Tunnel Junctions: Heat management and refrigeration are key concepts for nanoscale devices\noperating at cryogenic temperatures. The design of an on-chip mesoscopic\nrefrigerator that works thanks to the input heat is presented, thus realizing a\nsolid state implementation of the concept of cooling by heating. The system\nconsists of a circuit featuring a thermoelectric element based on a\nferromagnetic insulator-superconductor tunnel junction (N-FI-S) and a series of\ntwo normal metal-superconductor tunnel junctions (SINIS). The N-FI-S element\nconverts the incoming heat in a thermovoltage, which is applied to the SINIS,\nthereby yielding cooling. The cooler's performance is investigated as a\nfunction of the input heat current for different bath temperatures. We show\nthat this system can efficiently employ the performance of SINIS refrigeration,\nwith a substantial cooling of the normal metal island. Its scalability and\nsimplicity in the design makes it a promising building block for\nlow-temperature on-chip energy management applications.",
        "positive": "Non-linear dynamics near exceptional points of synthetic\n  antiferromagnetic spin-torque oscillators: We consider a synthetic antiferromagnetic spin-torque oscillator with\nanisotropic interlayer exchange coupling. This system exhibits exceptional\npoints in its linearized dynamics. We find the non-linear dynamics and the\ndynamical phase diagram of the system both analytically and numerically.\nMoreover, we show that, near one of the exceptional points, the power of the\noscillator depends extremely sensitively on the injected spin current. Our\nfindings may be useful for designing sensitive magnetometers and for other\napplications of spin-torque oscillators."
    },
    {
        "anchor": "Criticality in the crossed Andreev reflection of a quantum Hall edge: We develop a theory of the non-local transport of two counter-propagating\n$\\nu = 1$ quantum Hall edges coupled via a narrow disordered superconductor.\nThe system is self-tuned to the critical point between trivial and topological\nphases by the competition between tunneling processes with or without\nparticle-hole conversion. The critical conductance is a random, sample-specific\nquantity with a zero average and unusual bias dependence. The negative values\nof conductance are relatively stable against variations of the carrier density,\nwhich may make the critical state to appear as a topological one.",
        "positive": "Exchange interaction between magnetic adatoms on surfaces of noble\n  metals: We present first principles calculations of the exchange interactions between\nmagnetic impurities deposited on (001), (110) and (111) surfaces of Cu and Au\nand analyze them, in particular, in the asymptotic regime. For the (110) and\nthe (111) surfaces we demonstrate that the interaction shows an oscillatory\nbehavior as a function of the distance, R, of the impurities and that the\namplitude of the oscillations decays as 1/R^2. Furthermore, the frequency of\nthe oscillations is closely related to the length of the Fermi vector of the\nsurface states existing on these surfaces. Due to the asymmetry of the the\nsurface states' dispersion, the frequency of the oscillations becomes also\nasymmetric on the (110) surfaces, while on the Au(111) surface two distinct\nfrequencies are found in the oscillations as a consequence of the\nBychkov-Rashba splitting of the surface states. Remarkably, no long range\noscillations of the exchange interaction are observed for the (001) surfaces\nwhere the surface states are unoccupied. When burying the impurities beneath\nthe surface layer, oscillations mediated by the bulk states become visible."
    },
    {
        "anchor": "Contrast in transmission spectroscopy of a single quantum dot: We perform transmission spectroscopy on single quantum dots and examine the\neffects of a resident carriers spin, the incident laser spot size,\npolarization, and power on the experimental contrast. We demonstrate a factor\nof 4 improvement in the maximum contrast by using a solid immersion lens to\ndecrease the spot area. This increase yields a maximum signal to noise ratio of\n2000 Hz-1/2, which will allow for MHz detection frequencies. We anticipate that\nthis improvement will allow further investigation of spectral fluctuation and\nopen up the feasibility for an all-optical read-out of an electron spin in a\nquantum dot.",
        "positive": "Plasmon Enhanced Faraday Rotation in Thin Films: We have analyzed analytically the Faraday rotation of an electromagnetic wave\nfor magnetoactive thin metallic film with a nanostructured surface profile.\nPeriodical as well as random surface profiles were considered. The plasmon\ncontribution to the Faraday angle was studied. For periodical grating case, we\nhave shown that the maximum of rotation angle is achieved when surface plasmon\nwave number coincides with one of the wave numbers of the inverse lattice.\nEnhancement of the Faraday angle at plasmonic band edges is predicted. In the\ncase of random surface profile, it is shown that the diffusion of surface\nmagnetoplasmons gives a dominant contribution to Faraday rotation. Comparison\nwith the experiments is carried out."
    },
    {
        "anchor": "Three-Dimensional Quantum Anomalous Hall Effect in Magnetic Topological\n  Insulator Trilayers of Hundred-Nanometer Thickness: Magnetic topological states refer to a class of exotic phases in magnetic\nmaterials with their non-trivial topological property determined by magnetic\nspin configurations. An example of such states is the quantum anomalous Hall\n(QAH) state, which is a zero magnetic field manifestation of the quantum Hall\neffect. Current research in this direction focuses on QAH insulators with a\nthickness of less than 10nm. The thick QAH insulators in the\nthree-dimensional(3D) regime are limited, largely due to inevitable bulk\ncarriers being introduced in thick magnetic TI samples. Here, we employ\nmolecular beam epitaxy (MBE) to synthesize magnetic TI trilayers with a\nthickness of up to ~106 nm. We find these samples exhibit well-quantized Hall\nresistance and vanishing longitudinal resistance at zero magnetic field. By\nvarying magnetic dopants, gate voltages, temperature, and external magnetic\nfields, we examine the properties of these thick QAH insulators and demonstrate\nthe robustness of the 3D QAH effect. The realization of the well-quantized 3D\nQAH effect indicates that the nonchiral side surface states of our thick\nmagnetic TI trilayers are gapped and thus do not affect the QAH quantization.\nThe 3D QAH insulators of hundred-nanometer thickness provide a promising\nplatform for the exploration of fundamental physics, including axion physics\nand image magnetic monopole, and the advancement of electronic and spintronic\ndevices to circumvent Moore's law.",
        "positive": "Cyclotron resonance of single valley Dirac fermions in gapless HgTe\n  quantum well: We report on Landau level spectroscopy studies of two HgTe quantum wells\n(QWs) near or at the critical well thickness, where the band gap vanishes. In\nmagnetic fields up to $B$=16T, oriented perpendicular to the QW plane, we\nobserve a $\\sqrt{B}$ dependence for the energy of the dominant cyclotron\nresonance (CR) transition characteristic of two-dimensional Dirac fermions. The\ndominant CR line exhibits either a single or double absorption lineshape for\nthe gapless or gapped QW. Using an effective Dirac model, we deduce the band\nvelocity of single valley Dirac fermions in gapless HgTe quantum wells,\n$v_F=6.4 \\times10^5$ m/s, and interpret the double absorption of the gapped QW\nas resulting from the addition of a small relativistic mass."
    },
    {
        "anchor": "A vertical gate-defined double quantum dot in a strained germanium\n  double quantum well: Gate-defined quantum dots in silicon-germanium heterostructures have become a\ncompelling platform for quantum computation and simulation. Thus far,\ndevelopments have been limited to quantum dots defined in a single plane. Here,\nwe propose to advance beyond planar systems by exploiting heterostructures with\nmultiple quantum wells. We demonstrate the operation of a gate-defined vertical\ndouble quantum dot in a strained germanium double quantum well. In quantum\ntransport measurements we observe stability diagrams corresponding to a double\nquantum dot system. We analyze the capacitive coupling to the nearby gates and\nfind two quantum dots accumulated under the central plunger gate. We extract\nthe position and estimated size, from which we conclude that the double quantum\ndots are vertically stacked in the two quantum wells. We discuss challenges and\nopportunities and outline potential applications in quantum computing and\nquantum simulation.",
        "positive": "Complementary lateral-spin-orbit building blocks for programmable logic\n  and in-memory computing: Current-driven switching of nonvolatile spintronic materials and devices\nbased on spin-orbit torques offer fast data processing speed, low power\nconsumption, and unlimited endurance for future information processing\napplications. Analogous to conventional CMOS technology, it is important to\ndevelop a pair of complementary spin-orbit devices with differentiated\nmagnetization switching senses as elementary building blocks for realizing\nsophisticated logic functionalities. Various attempts using external magnetic\nfield or complicated stack/circuit designs have been proposed, however, plainer\nand more feasible approaches are still strongly desired. Here we show that a\npair of two locally laser annealed perpendicular Pt/Co/Pt devices with opposite\nlaser track configurations and thereby inverse field-free lateral spin-orbit\ntorques (LSOTs) induced switching senses can be adopted as such complementary\nspin-orbit building blocks. By electrically programming the initial\nmagnetization states (spin down/up) of each sample, four Boolean logic gates of\nAND, OR, NAND and NOR, as well as a spin-orbit half adder containing an XOR\ngate, were obtained. Moreover, various initialization-free, working current\nintensity-programmable stateful logic operations, including the material\nimplication (IMP) gate, were also demonstrated by regarding the magnetization\nstate as a logic input. Our complementary LSOT building blocks provide an\napplicable way towards future efficient spin logics and in-memory computing\narchitectures."
    },
    {
        "anchor": "New type of helical topological superconducting pairing at finite\n  excitation energies: We propose a new type of helical topological superconductivity away from the\nFermi surface in three-dimensional time-reversal-symmetric odd-parity multiband\nsuperconductors. In these systems, pairing between electrons originating from\ndifferent bands is responsible for the corresponding topological phase\ntransition. Consequently, a pair of helical topological Dirac surface states\nemerges at finite excitation energies. These helical Dirac surface states are\ntunable in energy by chemical potential and strength of band-splitting. They\nare protected by time-reversal symmetry combined with crystalline two-fold\nrotation symmetry. We suggest concrete materials in which this phenomenon could\nbe observed.",
        "positive": "Eddy-current effects on ferromagnetic resonance: Spin wave excitations\n  and microwave screening effects: We investigate how controlling induced eddy currents in thin film\nferromagnet-normal metal (FM/NM) structures can be used to tailor the local\nmicrowave (MW) fields in ferromagnetic resonance (FMR) experiments. The MW\nfields produced by eddy currents will in general have a relative phase shift\nwith respect to the applied MW field which depends on the sample geometry. The\ninduced fields can thus partially compensate the applied MW field, effectively\nscreening the FM in selected parts of the sample. The highly localized fields\nproduced by eddy currents enable the excitation of spin wave modes with\nnon-zero wave vectors, in contrast to the uniform k = 0 mode normally excited\nin FMR experiments. We find that the orientation of the applied MW field is one\nof the key parameters controlling the eddy-current effects. The induced\ncurrents are maximized when the applied MW field is oriented perpendicular to\nthe sample plane. Increasing the magnitude of the eddy currents results in a\nstronger induced MW field, enabling a more effective screening of the applied\nMW field as well as an enhanced excitation of spin wave modes. This\ninvestigation underlines that eddy currents can be used to control the\nmagnitude and phase of the local MW fields in thin film structures."
    },
    {
        "anchor": "Pseudo-hydrodynamic flow of quasiparticles in semimetal WTe2 at room\n  temperature: Recently, much interest has emerged in fluid-like electric charge transport\nin various solid-state systems. The hydrodynamic behavior of the electronic\nfluid reveals itself as a decrease of the electrical resistance with increasing\ntemperature (the Gurzhi effect) in narrow conducting channels, polynomial\nscaling of the resistance as a function of the channel width, substantial\nviolation of the Wiedemann-Franz law supported by the emergence of the\nPoiseuille flow. Similarly to whirlpools in flowing water, the viscous\nelectronic flow generates vortices, resulting in abnormal sign-changing\nelectrical response driven by the backflow of electrical current.\nExperimentally, the presence of the hydrodynamic vortices was observed in\nlow-temperature graphene as a negative voltage drop near the current-injecting\ncontacts. However, the question of whether the long-ranged sign-changing\nelectrical response can be produced by a mechanism other than hydrodynamics has\nnot been addressed so far. Here we use polarization-sensitive laser microscopy\nto demonstrate the emergence of visually similar abnormal sign-alternating\npatterns in charge density in multilayer tungsten ditelluride at room\ntemperature where this material does not exhibit true electronic hydrodynamics.\nWe argue that this pseudo-hydrodynamic behavior appears due to a subtle\ninterplay between the diffusive transport of electrons and holes. In\nparticular, the sign-alternating charge accumulation in WTe2 is supported by\nthe unexpected backflow of compressible neutral electron-hole current, which\ncreates charge-neutral whirlpools in the bulk of this nearly compensated\nsemimetal. We demonstrate that the exceptionally large spatial size of the\ncharge domains is sustained by the long recombination time of electron-hole\npairs.",
        "positive": "Ultrafast Dynamics of Defect-Assisted Electron-Hole Recombination in\n  Monolayer MoS2: In this letter, we present non-degenerate ultrafast optical pump-probe\nstudies of the carrier recombination dynamics in MoS$_{2}$ monolayers. By\ntuning the probe to wavelengths much longer than the exciton line, we make the\nprobe transmission sensitive to the total population of photoexcited electrons\nand holes. Our measurement reveals two distinct time scales over which the\nphotoexcited electrons and holes recombine; a fast time scale that lasts\n$\\sim$2 ps and a slow time scale that lasts longer than $\\sim$100 ps. The\ntemperature and the pump fluence dependence of the observed carrier dynamics\nare consistent with defect-assisted recombination as being the dominant\nmechanism for electron-hole recombination in which the electrons and holes are\ncaptured by defects via Auger processes. Strong Coulomb interactions in two\ndimensional atomic materials, together with strong electron and hole\ncorrelations in two dimensional metal dichalcogenides, make Auger processes\nparticularly effective for carrier capture by defects. We present a model for\ncarrier recombination dynamics that quantitatively explains all features of our\ndata for different temperatures and pump fluences. The theoretical estimates\nfor the rate constants for Auger carrier capture are in good agreement with the\nexperimentally determined values. Our results underscore the important role\nplayed by Auger processes in two dimensional atomic materials."
    },
    {
        "anchor": "Topological spin current: We present an exact derivation for non-commuting coordinates induced by the\nSU(2) transformation used to diagonalize the spin-orbit hamiltonian in two\ndimension.As a result an exact non-dissipative Hall current less sensitive to\ndisorder and complementary to the dissipative conductivity is found.\n  We compute the non-dissipative charge and spin-Hall conductance for the\nspin-orbit problem.We find that the spin-Hall conductance is quantized in units\nof $\\frac{eg\\mu_{B}}{h}$ .In the presence of a Zeeman interaction the\ncharge-Hall conductivity is proportional to the magnetic field. We propose an\nexperiment to test our theory.",
        "positive": "Atomically-thin Ohmic Edge Contacts Between Two-dimensional Materials: With the decrease of the dimensions of electronic devices, the role played by\nelectrical contacts is ever increasing, eventually coming to dominate the\noverall device volume and total resistance. This is especially problematic for\nmonolayers of semiconducting transition metal dichalcogenides (TMDs), which are\npromising candidates for atomically thin electronics. Ideal electrical contacts\nto them would require the use of similarly thin electrode materials while\nmaintaining low contact resistances. Here we report a scalable method to\nfabricate ohmic graphene edge contacts to two representative monolayer TMDs -\nMoS2 and WS2. The graphene and TMD layer are laterally connected with\nwafer-scale homogeneity, no observable overlap or gap, and a low average\ncontact resistance of 30 k$\\Omega$ $\\mu$m. The resulting graphene edge contacts\nshow linear current-voltage (IV) characteristics at room temperature, with\nohmic behavior maintained down to liquid helium temperatures."
    },
    {
        "anchor": "Quantum transport in a mesoscopic ring: Evidence of an OR gate: We explore OR gate response in a mesoscopic ring threaded by a magnetic flux\n$\\phi$. The ring is symmetrically attached to two semi-infinite one-dimensional\nmetallic electrodes and two gate voltages, viz, $V_a$ and $V_b$, are applied in\none arm of the ring which are treated as the two inputs of the OR gate. All the\ncalculations are based on the tight-binding model and the Green's function\nmethod, which numerically compute the conductance-energy and current-voltage\ncharacteristics as functions of the gate voltages, ring-to-electrodes coupling\nstrengths and magnetic flux. Our theoretical study shows that, for\n$\\phi=\\phi_0/2$ ($\\phi_0=ch/e$, the elementary flux-quantum) a high output\ncurrent (1) (in the logical sense) appears if one or both the inputs to the\ngate are high (1), while if neither input is high (1), a low output current (0)\nappears. It clearly demonstrates the OR gate behavior and this aspect may be\nutilized in designing the electronic logic gate.",
        "positive": "Realizing high current gain PNP transistors using a novel Surface\n  Accumulation Layer Transistor (SALTran) concept: In this paper we report a new PNP Surface Accumulation Layer Transistor\n(SALTran) on SOI which uses the concept of surface accumulation of holes near\nthe emitter contact to significantly improve the current gain. Using\ntwo-dimensional simulation, we have evaluated the performance of the proposed\ndevice in detail by comparing its characteristics with those of the previously\npublished conventional PNP lateral bipolar transistor (LBT) structure. From our\nsimulation results it is observed that depending on the choice of the emitter\ndoping and the emitter length, the proposed SALTran exhibits a current gain\nenhancement of around 20 times that of the compatible lateral bipolar\ntransistor without deteriorating the cut-off frequency. We have discussed the\nreasons for the improved performance of the SALTran based on our detailed\nsimulation results."
    },
    {
        "anchor": "Thermal conductivity of one-dimensional carbon-boron nitride van der\n  Waals heterostructure: A molecular dynamics study: Investigating thermal transport in van der Waals heterostructure is of\nscientific interest and practical importance for their applications in a broad\nrange. In this work, thermal conductivity of one-dimensional heterostructure\nconsisting of carbon and boron nitride nanotubes is systematically investigated\nvia molecular dynamics simulations. Thermal conductivity is found to have\nstrong dependences on temperature, length and diameter. In addition, the axial\nstrain and intensity of van der Waals interaction are demonstrated to be able\nto modulate thermal conductivity up to about 43% and 37%, respectively.\nMoreover, the dependence of thermal conductivity on the chirality of\ncomponential nanotubes is studied. These results are explained based on lattice\ndynamics insights. This work not only provides feasible strategies to modulate\nthermal conductivity, but also enhances the understanding of the fundamental\nphysics of phonon transport in one-dimensional heterostructure.",
        "positive": "Theory of dynamical stability for two- and three-dimensional\n  Lennard-Jones crystals: The dynamical stability of three-dimensional (3D) Lennard-Jones (LJ) crystals\nhas been studied for many years. The face-centered-cubic and hexagonal close\npacked structures are dynamically stable, while the body-centered cubic\nstructure is stable only for long range LJ potentials that are characterized by\nrelatively small integer pairs $(m,n)$. Here, we study the dynamical stability\nof two-dimensional (2D) LJ crystals, where the planar hexagonal, the buckled\nhoneycomb, and the buckled square structures are assumed. We demonstrate that\nthe stability property of 2D and 3D LJ crystals can be classified into four\ngroups depending on $(m,n)$. The instabilities of the planar hexagonal, the\nbuckled square, and the body-centered cubic structures are investigated within\nanalytical expressions. The structure-stability relationship between the LJ\ncrystals and the elemental metals in the periodic table is also discussed."
    },
    {
        "anchor": "Tunable Phases of Moir\u00e9 Excitons in van der Waals Heterostructures: Stacking monolayers of transition metal dichalcogenides into a\nheterostructure with a finite twist-angle gives rise to artificial moir\\'e\nsuperlattices with a tunable periodicity. As a consequence, excitons experience\na periodic potential, which can be exploited to tailor optoelectronic\nproperties of these materials. While recent experimental studies have confirmed\ntwist-angle dependent optical spectra, the microscopic origin of moir\\'e\nexciton resonances has not been fully clarified yet. Here, we combine first\nprinciple calculations with the excitonic density matrix formalism to study\ntransitions between different moir\\'e exciton phases and their impact on\noptical properties of the twisted MoSe$_2$/WSe$_2$ heterostructure. At angles\nsmaller than 2$^{\\circ}$ we find flat, moir\\'e trapped states for inter- and\nintralayer excitons. This moir\\'e exciton phase drastically changes into\ncompletely delocalized states already at 3$^{\\circ}$. We predict a linear and\nquadratic twist-angle dependence of excitonic resonances for the\nmoir\\'e-trapped and delocalized exciton phase, respectively. Our work provides\nmicroscopic insights opening the possibility to tailor moir\\'e exciton phases\nin van der Waals superlattices.",
        "positive": "Time dependence of transmission in semiconductor superlattices: Time delay in electron propagation through a finite periodic system such as a\nsemiconductor superlattice is studied by direct numerical solution of the\ntime-dependent Schr\\\"odinger equation. It is found that addition of an\nanti-reflection coating significantly reduces the time delay, in addition to\nincreasing the transmissivity."
    },
    {
        "anchor": "Assessment of High-Frequency Performance Limits of Graphene Field-Effect\n  Transistors: High frequency performance limits of graphene field-effect transistors (FETs)\ndown to a channel length of 20nm are examined by using self-consistent quantum\nsimulations. The results indicate that although Klein band-to-band tunneling is\nsignificant for sub-100nm graphene FET, it is possible to achieve a good\ntransconductance and ballistic on-off ratio larger than 3 even at a channel\nlength of 20nm. At a channel length of 20nm, the intrinsic cut-off frequency\nremains at a couple of THz for various gate insulator thickness values, but a\nthin gate insulator is necessary for a good transconductance and smaller\ndegradation of cut-off frequency in the presence of parasitic capacitance. The\nintrinsic cut-off frequency is close to the LC characteristic frequency set by\ngraphene kinetic inductance and quantum capacitance, which is about 100GHz\n\\cdot {\\mu}m divided by the gate length.",
        "positive": "Opportunities for the direct manipulation of a phase-driven Andreev spin\n  qubit: In a Josephson junction, the transfer of Cooper pairs from one superconductor\nto the other one can be associated with the formation of Andreev bound states.\nIn a Josephson junction made with a semiconducting nanowire, the spin\ndegeneracy of these Andreev states can be broken thanks to the presence of\nspin-orbit coupling and a finite phase difference between the two\nsuperconducting electrodes. The lifting of the spin degeneracy opened the way\nto the realization of Andreev spin qubits that do not require the application\nof a large magnetic field. So far the operation of these qubits relied on a\nRaman process involving two microwave tones and a third Andreev state [M. Hays\net al., Science 373, 430 (2021)]. Still, time-reversal preserving impurities in\nthe nanowire allow for spin-flip scattering processes. Here, using the\nformalism of scattering matrices, we show that these processes generically\ncouple Andreev states with opposite spins. In particular, the non-vanishing\ncurrent matrix element between them allows for the direct manipulation of\nphase-driven Andreev spin qubits, thereby circumventing the use of the\nabove-mentioned Raman process."
    },
    {
        "anchor": "Andreev reflection of fractional quantum Hall quasiparticles: Electron correlation in a quantum many-body state appears as peculiar\nscattering behaviour at its boundary, symbolic of which is Andreev reflection\nat a metal-superconductor interface. Despite being fundamental in nature,\ndictated by the charge conservation law, however, the process has had no\nanalogues outside the realm of superconductivity so far. Here, we report the\nobservation of an Andreev-like process originating from a topological quantum\nmany-body effect instead of superconductivity. A narrow junction between\nfractional and integer quantum Hall states shows a two-terminal conductance\nexceeding that of the constituent fractional state. This remarkable behaviour,\nwhile theoretically predicted more than two decades ago but not detected to\ndate, can be interpreted as Andreev reflection of fractionally charged\nquasiparticles. The observed fractional quantum Hall Andreev reflection\nprovides a fundamental picture that captures microscopic charge dynamics at the\nboundaries of topological quantum many-body states.",
        "positive": "Current-induced forces in nanosystems: A hierarchical equations of\n  motion approach: A new approach to calculating current-induced forces in charge transport\nthrough nanosystems is introduced. Starting from the fully quantum mechanical\nhierarchical equations of motion formalism, a timescale separation between\nelectronic and vibrational degrees of freedom is used to derive a classical\nLangevin equation of motion for the vibrational dynamics as influenced by\ncurrent-induced forces, such as the electronic friction. The resulting form of\nthe friction is shown to be equivalent to previously derived expressions. The\nnumerical exactness of the hierarchical equations of motion approach, however,\nallows the investigation of transport scenarios with strong intrasystem and\nsystem-environment interactions. As a demonstration, the electronic friction of\nthree example systems is calculated and analyzed: a single electronic level\ncoupled to one classical vibrational mode, two electronic levels coupled to one\nclassical vibrational mode, and a single electronic level coupled to both a\nclassical and quantum vibrational mode."
    },
    {
        "anchor": "Strain Induced Modulation of Local Transport of 2D Materials at the\n  Nanoscale: Strain engineering offers unique control to manipulate the electronic band\nstructure of two-dimensional materials (2DMs) resulting in an effective and\ncontinuous tuning of the physical properties. Ad-hoc straining 2D materials has\ndemonstrated novel devices including efficient photodetectors at\ntelecommunication frequencies, enhanced-mobility transistors, and on-chip\nsingle photon source, for example. However, in order to gain insights into the\nunderlying mechanism required to enhance the performance of the next-generation\ndevices with strain(op)tronics, it is imperative to understand the nano- and\nmicroscopic properties as a function of a strong non-homogeneous strain. Here,\nwe study the strain-induced variation of local conductivity of a few-layer\ntransition-metal-dichalcogenide using a conductive atomic force microscopy. We\nreport a novel strain characterization technique by capturing the electrical\nconductivity variations induced by local strain originating from surface\ntopography at the nanoscale, which allows overcoming limitations of existing\noptical spectroscopy techniques. We show that the conductivity variations\nparallel the strain deviations across the geometry predicted by molecular\ndynamics simulation. These results substantiate a variation of the effective\nmass and surface charge density by .026 me/% and .03e/% of uniaxial strain,\nrespectively. Furthermore, we show and quantify how a gradual reduction of the\nconduction band minima as a function of tensile strain explains the observed\nreduced effective Schottky barrier height. Such spatially-textured electronic\nbehavior via surface topography induced strain variations in atomistic-layered\nmaterials at the nanoscale opens up new opportunities to control fundamental\nmaterial properties and offers a myriad of design and functional device\npossibilities for electronics, nanophotonics, flextronics, or smart cloths.",
        "positive": "Coherent properties of nano-electromechanical systems: We study the properties of a nano-electromechanical system in the coherent\nregime, where the electronic and vibrational time scales are of the same order.\nEmploying a master equation approach, we obtain the stationary reduced density\nmatrix retaining the coherences between vibrational states. Depending on the\nsystem parameters, two regimes are identified, characterized by either ($i$) an\n{\\em effective} thermal state with a temperature {\\em lower} than that of the\nenvironment or ($ii$) strong coherent effects. A marked cooling of the\nvibrational degree of freedom is observed with a suppression of the vibron Fano\nfactor down to sub-Poissonian values and a reduction of the position and\nmomentum quadratures."
    },
    {
        "anchor": "Charge sensitivity of the Inductive Single-Electron Transistor: We calculate the charge sensitivity of a recently demonstrated device where\nthe Josephson inductance of a single Cooper-pair transistor is measured. We\nfind that the intrinsic limit to detector performance is set by oscillator\nquantum noise. Sensitivity better than $10^{-6}$e$/\\sqrt{\\mathrm{Hz}}$ is\npossible with a high $Q$-value $\\sim 10^3$, or using a SQUID amplifier. The\nmodel is compared to experiment, where charge sensitivity $3 \\times\n10^{-5}$e$/\\sqrt{\\mathrm{Hz}}$ and bandwidth 100 MHz are achieved.",
        "positive": "Adatoms and clusters of 3d transition metals on graphene: Electronic and\n  magnetic configurations: We investigate the electronic and magnetic properties of single Fe, Co, and\nNi atoms and clusters on monolayer graphene (MLG) on SiC(0001) by means of\nscanning tunneling microscopy (STM), x-ray absorption spectroscopy, x-ray\nmagnetic circular dichroism (XMCD), and ab initio calculations. STM reveals\ndifferent adsorption sites for Ni and Co adatoms. XMCD proves Fe and Co adatoms\nto be paramagnetic and to exhibit an out-of-plane easy axis in agreement with\ntheory. In contrast, we experimentally find a nonmagnetic ground state for Ni\nmonomers while an increasing cluster size leads to sizeable magnetic moments.\nThese observations are well reproduced by our calculations and reveal the\nimportance of hybridization effects and intra-atomic charge transfer for the\nproperties of adatoms and clusters on MLG."
    },
    {
        "anchor": "Non-Hermitian coupled-mode theory for incoherently pumped\n  exciton-polariton condensates: The generalized Gross-Pitaevskii equation (gGPE) is an effective\nphenomenological description for the dynamics of incoherently pumped\nexciton-polariton condensates. However, a brute force numerical simulation of\nthe gGPE provides little physical insight into condensate formation under\narbitrary pumping configurations, and is demanding in terms of computational\nresources. We introduce in this paper a modal description of polariton\ncondensation under incoherent pumping of arbitrary spatial profile, based on\neigenmodes of the non-Hermitian generator of the linearized dynamics. A\npump-dependent basis is then introduced to formulate a temporal coupled-mode\ntheory that captures condensate dynamics in the presence of all nonlinear\ninteractions. Simulations using a single set of modes for a given pumping and\ntrapping configuration agree very well with a full integration of the gGPE in\ndiverse dynamical regimes, supporting the validity of this modal description,\nwhile also providing a speedup in simulation times.",
        "positive": "Direct observation of handedness-dependent quasiparticle interference in\n  the two enantiomers of topological chiral semimetal PdGa: It has recently been proposed that combining chirality with topological band\ntheory may result in a totally new class of fermions. These particles have\ndistinct properties: they appear at high symmetry points of the reciprocal\nlattice, they are connected by helicoidal surface Fermi arcs spanning the\nentire Brillouin zone, and they are expected to exist over a large energy\nrange. Additionally, they are expected to give rise to totally new effects\nforbidden in other topological classes. Understanding how these unconventional\nquasiparticles propagate and interact is crucial for exploiting their potential\nin innovative chirality-driven device architectures. These aspects necessarily\nrely on the detection of handedness-dependent effects in the two enantiomers\nand remain largely unexplored so far. Here, we use scanning tunnelling\nmicroscopy to visualize the electronic properties of both enantiomers of the\nprototypical chiral topological semimetal PdGa at the atomic scale. We reveal\nthat the surface-bulk connectivity goes beyond ensuring the existence of\ntopological Fermi arcs, but also determines how quasiparticles propagate and\nscatter at impurities, giving rise to chiral quantum interference patterns of\nopposite handedness and opposite spiralling direction for the two different\nenantiomers, a direct manifestation of the change of sign of their Chern\nnumber. Additionally, we demonstrate that PdGa remains topologically\nnon-trivial over a large energy range, experimentally detecting Fermi arcs in\nan energy window of more than 1.6 eV symmetrically centerd around the Fermi\nlevel. These results are rationalized in terms of the deep connection between\nchirality in real and reciprocal space in this class of materials, and they\nallow to identify PdGa as an ideal topological chiral semimetal."
    },
    {
        "anchor": "Coulomb blockade effects in anodised niobium nanostructures: Niobium thin film wires were fabricated using electron beam lithography with\na four layer liftoff mask system, and subsequently thinned by anodisation. The\nresistance along the wire was monitored in situ and trimmed by controlling the\nanodisation voltage. Depending on the room temperature sheet resistance,\nsamples showed either superconducting or insulating behaviour at low\ntemperatures. A Coulomb blockade was observed for samples exceeding 6 kOhm per\nsquare. Samples were also made in a single electron transistor-like geometry\nwith two weak links made by combined angular evaporation and anodisation. Their\ncurrent-voltage characteristics could be modulated by a voltage applied to an\noverlapping gate.",
        "positive": "Exciton interference in hexagonal boron nitride: In this letter we report a thorough analysis of the exciton dispersion in\nbulk hexagonal boron nitride. We solve the ab initio GW Bethe-Salpeter equation\nat finite $\\mathbf{q}\\parallel \\Gamma K$, and we compare our results with\nrecent high-accuracy electron energy loss data. Simulations reproduce the\nmeasured dispersion and the variation of the peak intensity. We focus on the\nevolution of the intensity, and we demonstrate that the excitonic peak is\nformed by the superposition of two groups of transitions that we call $KM$ and\n$MK'$ from the k-points involved in the transitions. These two groups\ncontribute to the peak intensity with opposite signs, each damping the\ncontributions of the other. The variations in number and amplitude of these\ntransitions determine the changes in intensity of the peak. Our results\ncontribute to the understanding of electronic excitations in this systems along\nthe $\\Gamma K$ direction, which is the relevant direction for spectroscopic\nmeasurements. They also unveil the non-trivial relation between valley physics\nand excitonic dispersion in h--BN, opening the possibility to tune excitonic\neffects by playing with the interference between transitions. Furthermore, this\nstudy introduces analysis tools and a methodology that are completely general.\nThey suggest a way to regroup independent-particle transitions which could\npermit a deeper understanding of excitonic properties in any system."
    },
    {
        "anchor": "Observation of the orbital Hall effect in a light metal Ti: The orbital angular momentum is a core ingredient of orbital magnetism, spin\nHall effect, giant Rashba spin splitting, orbital Edelstein effect, and\nspin-orbit torque. However, its experimental detection is tricky. In\nparticular, direct detection of the orbital Hall effect remains elusive despite\nits importance for electrical control of magnetic nanodevices. Here we report\nthe direct observation of the orbital Hall effect in a light metal Ti. The Kerr\nrotation by the accumulated orbital magnetic moment is measured at Ti surfaces,\nwhose result agrees with theoretical calculations semiquantitatively and is\nsupported by the orbital torque measurement in Ti-based magnetic\nheterostructures. The results confirm the electron orbital angular momentum as\nan essential dynamic degree of freedom, which may provide a novel mechanism for\nthe electric control of magnetism. The results may also deepen the\nunderstanding of spin, valley, phonon, and magnon dynamics coupled with orbital\ndynamics.",
        "positive": "Ultraconfined plasmons in atomically thin crystalline silver\n  nanostructures: The ability to confine light down to atomic scales is critical for the\ndevelopment of applications in optoelectronics and optical sensing as well as\nfor the exploration of nanoscale quantum phenomena. Plasmons in metallic\nnanostructures can achieve this type of confinement, although fabrication\nimperfections down to the subnanometer scale hinder actual developments. Here,\nwe demonstrate narrow plasmons in atomically thin crystalline silver\nnanostructures fabricated by prepatterning silicon substrates and epitaxially\ndepositing silver films of just a few atomic layers in thickness. Combined with\non-demand lateral shaping, this procedure allows for an unprecedented control\nover optical field confinement in the near-infrared spectral region.\nSpecifically, we observe fundamental and higher-order plasmons featuring\nextreme spatial confinement and high-quality factors that reflect the\ncrystallinity of the metal. Our approach holds potential for the design and\nexploitation of atomic-scale nanoplasmonic devices in optoelectronics, sensing,\nand quantum-physics applications."
    },
    {
        "anchor": "Theory of intermolecular exchange in coupled spin-1/2 nanographenes: Open-shell nanographenes can be covalently bonded and still preserve their\nlocal moments, forming interacting spins lattices. In the case of benzenoid\nnanographenes, the Ovchinnikov-Lieb rules anticipate the spin of the ground\nstate of the superstructure, and thereby the sign of the intermolecular\nexchange. Here we address the underlying microscopic mechanisms for\nintermolecular exchange in this type of system. We find that, in general, three\ndifferent mechanisms contribute. First, Hund's ferromagnetic exchange that\npromotes ferromagnetic interactions of electrons in overlapping orbitals.\nSecond, superexchange driven by intermolecular hybridization, identical to\nAnderson kinetic exchange, which is a decreasing function of the Hubbard-$U$\nenergy scale, and is always antiferromagnetic. Third, a Coulomb-driven\nsuperexchange, that increases as a function of $U$, and involves virtual\nexcitation of excited molecular orbitals that are extended over the entire\nstructure. We find that Coulomb-driven superexchange can be either ferro or\nantiferromagnetic, accounting for Ovchinnikov-Lieb rules. We compute these\nexchange energies for the case of coupled $S=1/2$ phenalenyl triangulenes,\nusing multi-configurational methods both with Hubbard and extended Hubbard\nmodels, thereby addressing the influence of long-range Coulomb interactions on\nthe exchange interactions.",
        "positive": "Step-like features on caloric effects of graphenes: We considered a graphene nano-ribbon with a longitudinal electric field\n(along $x$ direction) and a transversal magnetic field (along $z$ direction),\nand then observe (i) the electrocaloric effect ruled by an applied magnetic\nfield and (ii) the magnetocaloric effect ruled by an applied electric field. We\nfocused our attention to the limit of low temperatures, and then observed\ninteresting step-like features. For each filled Landau level $n$, created by\nthe applied magnetic field, both caloric effects increase proportionally to\n$n+1/2$; and this step measures either important graphene properties (like\nFermi velocity) or quantum fundamental quantities (like Planck constant and\nmagnetic flux quantum)."
    },
    {
        "anchor": "Towards the detection of ultra-low energetic neutrinos with plasma\n  metamaterials: Experiments as IceCube or Super-Kamiokande have been successful in detecting\nhighly energetic neutrinos in the. Neutrinos in the ultra-low energy range\n($\\mathcal{E}<1.0~\\rm{eV}$) have been theoretically predicted but their\nobservation remain elusive, and no concrete experimental scheme has been\nproposed for that job. Here, we propose a novel scheme based on graphene\nplasmonic metamaterials to designed to detect ultra-low energetic neutrinos. We\nclaim that slow neutrino fluxes, interacting with solid-state plasmas, can\ngenerate an instability due to the weak neutrino-plasmon interaction, which is\nreminiscent of the beam-plasma instability taking place in astrophysics and\nlaboratory plasmas. We make use of the semi-classical limit of the weak\ninteraction to describe the coupling between the neutrinos and electrons in\ngraphene. To render the scheme practical, we investigate the neutrino-plasma\ninstability produced in a graphene metamaterial, composed by a periodic\nstacking of graphene layers. Our findings reveal that the controlled excitation\nof plasma waves in such graphene metamaterial allows for the detection of\nneutrinos in the energy range $\\sim 1.0~\\rm{\\mu eV}-100~\\rm{meV}$, and fluxes\nin the range $10^{4}-10^{10} \\rm{cm^{-2} s^{-1}}$.",
        "positive": "Charge Puddles in Graphene Near the Dirac Point: The charge carrier density in graphene on a dielectric substrate such as\nSiO$_2$ displays inhomogeneities, the so-called charge puddles. Because of the\nlinear dispersion relation in monolayer graphene, the puddles are predicted to\ngrow near charge neutrality, a markedly distinct property from conventional\ntwo-dimensional electron gases. By performing scanning tunneling\nmicroscopy/spectroscopy on a mesoscopic graphene device, we directly observe\nthe puddles' growth, both in spatial extent and in amplitude, as the Dirac\npoint is approached. Self-consistent screening theory provides a unified\ndescription of both the macroscopic transport properties and the\nmicroscopically observed charge disorder."
    },
    {
        "anchor": "Charge density wave transport in submicron antidot arrays in NbSe3: We demonstrate for the first time that a periodic array of submicrometer\nholes (antidots) can be patterned into thin single NbSe3 crystals. We report on\nthe study of charge density wave (CDW) transport of the network of mesoscopic\nunits between antidots. Size of the elementary unit can be as small as 0.5\nmicron along the chain axis and (0.2 micron) x (0.3 micron) in cross section.\nWe observe size effects for Ohmic residual resistance and in CDW transport\ncurrent-voltage characteristics in submicronic networks.",
        "positive": "Energy effective mass dependence of electron tunneling through CdS/CdSe,\n  AlxGa1-xAs/GaAs and AlSb/InAs Multiple Quantum Barriers: Tunneling of electrons through the barriers in heterostructures devices is\ninvestigated by using the unified Transfer Matrix Method. The effect of barrier\nwidth on electron transmission coefficients has also been examined for\ndifferent pairs of semiconductor devices of significant research interest in\ncurrent years. Such Pairs involve AlxGa1-xAs/GaAs, AlSb/InAs, and CdS/CdSe\nquantum barriers with varying dimensions reduced from 20 nm to 5nm to observe\nhow tunneling properties are affected by scaling. The effective electron masses\nin the well and barrier regions typically vary with constituent materials. It\nhas been shown that the transmission coefficients are significantly changed due\nto the coupling. The effective mass-dependent transmission coefficients for\nelectron energy have been evaluated in terms of the mass discontinuity metrics.\nThe electron transmission coefficients for each pair of quantum structures are\nplotted with the variation of its electron energy, normalized to its potential\nenergy. The resonant state obtained here will be beneficial for designing\ndetectors, optical filters, photonic-switching devices and other optoelectronic\nand photonic devices."
    },
    {
        "anchor": "Exciton Diamagnetic Shifts and Valley Zeeman Effects in Monolayer WS$_2$\n  and MoS$_2$ to 65 Tesla: We report circularly-polarized optical reflection spectroscopy of monolayer\nWS$_2$ and MoS$_2$ at low temperatures (4~K) and in high magnetic fields to\n65~T. Both the A and the B exciton transitions exhibit a clear and very similar\nZeeman splitting of approximately $-$230~$\\mu$eV/T ($g\\simeq -4$), providing\nthe first measurements of the valley Zeeman effect and associated $g$-factors\nin monolayer transition-metal disulphides. These results complement and are\ncompared with recent low-field photoluminescence measurements of valley\ndegeneracy breaking in the monolayer diselenides MoSe$_2$ and WSe$_2$. Further,\nthe very large magnetic fields used in our studies allows us to observe the\nsmall quadratic diamagnetic shifts of the A and B excitons in monolayer WS$_2$\n(0.32 and 0.11~$\\mu$eV/T$^2$, respectively), from which we calculate exciton\nradii of 1.53~nm and 1.16~nm. When analyzed within a model of non-local\ndielectric screening in monolayer semiconductors, these diamagnetic shifts also\nconstrain and provide estimates of the exciton binding energies (410~meV and\n470~meV for the A and B excitons, respectively), further highlighting the\nutility of high magnetic fields for understanding new 2D materials.",
        "positive": "Magneto-exciton in planar type II quantum dots: We study an exciton in a type II quantum dot, where the electron is confined\nin the dot, but the hole is located in the barrier material. The exciton\nproperties are studied as a function of a perpendicular magnetic field using a\nHartree-fock mesh calculation. Our model system consists of a planar quantum\ndisk. Angular momentum (l) transitions are predicted with increasing magnetic\nfield. We also study the transition from a type I to a type II quantum dot\nwhich is induced by changing the confinement potential of the hole. For\nsufficiently large magnetic fields a re-entrant behaviour is found from\n$l_{h}=0$ to $l_{h}\\neq 0$ and back to $l_{h}=0$, which results in a transition\nfrom type II to type I."
    },
    {
        "anchor": "The quantum anomalous Hall effect: The quantum anomalous Hall effect is defined as a quantized Hall effect\nrealized in a system without external magnetic field. Quantum anomalous Hall\neffect is a novel manifestation of topological structure in many-electron\nsystems, and may have potential applications in future electronic devices. In\nrecent years, quantum anomalous Hall effect has been proposed theoretically and\nrealized experimentally. In this review article, we provide a systematic\noverview of the theoretical and experimental developments in this field.",
        "positive": "Graphene nanoelectromechanical resonators for detection of modulated\n  terahertz radiation: We propose and analyze the detector of modulated terahertz (THz) radiation\nbased on the graphene field-effect transistor with mechanically floating gate\nmade of graphene as well. The THz component of incoming radiation induces\nresonant excitation of plasma oscillations in graphene layers (GLs). The\nrectified component of the ponderomotive force between GLs invokes resonant\nmechanical swinging of top GL, resulting in the drain current oscillations. To\nestimate the device responsivity, we solve the hydrodynamic equations for the\nelectrons and holes in graphene governing the plasma-wave response, and the\nequation describing the graphene membrane oscillations. The combined\nplasma-mechanical resonance raises the current amplitude by up to four orders\nof magnitude. The use of graphene as a material for the elastic gate and\nconductive channel allows the voltage tuning of both resonant frequencies in a\nwide range."
    },
    {
        "anchor": "Room temperature self-assembly of cation-free guanine quartet network\n  nucleated from Mo-induced defect on decorated Au(111) with graphene\n  nanoribbons: Guanine-quadruplex, consisting of several stacked guanine-quartets (GQs), has\nemerged as an important category of novel molecular targets with applications\nfrom nanoelectronic devices to anticancer drugs. Incorporation of metal cations\ninto GQ structure is utilized to form stable G-quadruplexes, while no other\npassage has been reported yet. Here we report the room temperature (RT)\nmolecular self-assembly of extensive metal-free GQ networks on Au(111) surface.\nSurface defect induced by an implanted molybdenum atom within Au(111) surface\nis used to nucleate and stabilize the cation-free GQ network. Additionally, the\ndecorated Au(111) surface with 7-armchair graphene nanoribbons (7-AGNRs)\nresults in more extensive GQ networks by curing the disordered phase nucleated\nfrom Au step edges spatially and chemically. Scanning tunneling\nmicroscopy/spectroscopy (STM/STS) and density functional theory (DFT)\ncalculations confirm GQ networks' formation and unravel the nucleation and\ngrowth mechanism. This method stimulates cation-free G-quartet network\nformation at RT and can lead to stabilizing new emerging molecular\nself-assembly.",
        "positive": "Quantum Hall resistances of multiterminal top-gated graphene device: Four-terminal resistances, both longitudinal and diagonal, of a locally gated\ngraphene device are measured in the quantum-Hall (QH) regime. In sharp\ndistinction from previous two-terminal studies [J. R. Williams \\textit{et al.},\nScience {\\bf 317}, 638 (2007); B. \\\"{O}zyilmaz \\textit{et al.}, Phys. Rev.\nLett. {\\bf 99}, 166804 (2007)], asymmetric QH resistances are observed, which\nprovide information on reflection as well as transmission of the QH edge\nstates. Most quantized values of resistances are well analyzed by the\nassumption that all edge states are equally populated. Contrary to the\nexpectation, however, a 5/2 transmission of the edge states is also found,\nwhich may be caused by incomplete mode mixing and/or by the presence of\ncounter-propagating edge states. This four-terminal scheme can be conveniently\nused to study the edge-state equilibration in locally gated graphene devices as\nwell as mono- and multi-layer graphene hybrid structures."
    },
    {
        "anchor": "Marginal Fermi liquid versus excitonic instability in 3D Dirac\n  semimetals: We study the different phases in the Quantum Electrodynamics of 3D Dirac\nsemimetals depending on the number $N$ of Dirac fermions, using renormalization\ngroup methods and the self-consistent resolution of the Schwinger-Dyson\nequation. We find that, for $N < 4$, a phase with dynamical generation of mass\nprevails at sufficiently strong coupling, sharing the same physics of the\nexcitonic instability in 2D Dirac semimetals. For $N \\geq 4$, we show that the\nphase diagram has instead a line of critical points characterized by the\nsuppression of the quasiparticle weight at low energies, making the system to\nfall into the class of marginal Fermi liquids. Such a boundary marks the\ntransition to a kind of strange metal which can be still defined in terms of\nelectron quasiparticles, but with parameters that have large imaginary parts\nimplying an increasing deviation from the conventional Fermi liquid picture.",
        "positive": "The Fano-Rashba effect: We analyze the linear conductance of a semiconductor quantum wire containing\na region where a local Rashba spin-orbit interaction is present. We show that\nFano lineshapes appear in the conductance due to the formation of quasi bound\nstates which interfere with the direct transmission along the wire, a mechanism\nthat we term the Fano-Rashba effect. We obtain the numerical solution of the\nfull Schr\\\"odinger equation using the quantum-transmitting-boundary method. The\ntheoretical analysis is performed using the coupled-channel model, finding an\nanalytical solution by ansatz. The complete numerical solution of the\ncoupled-channel equations is also discussed, showing the validity of the ansatz\napproach."
    },
    {
        "anchor": "One-dimensional van der Waals heterojunction diode: The synthesis of one-dimensional van der Waals heterostructures was realized\nrecently, which opens up new possibilities for prospective applications in\nelectronics and optoelectronics. The even reduced dimension will enable novel\nproperties and further miniaturization beyond the capabilities of its\ntwo-dimensional counterparts have revealed. The natural doping results in\np-type electrical characteristics for semiconducting single-walled carbon\nnanotubes, while n-type for molybdenum disulfide with conventional noble metal\ncontacts. Therefore, we demonstrate here a one-dimensional heterostructure\nnanotube of 11-nm-wide, with the coaxial assembly of semiconducting\nsingle-walled carbon nanotube, insulating boron nitride nanotube, and\nsemiconducting molybdenum disulfide nanotube which induces a radial\nsemiconductor-insulator-semiconductor heterojunction. When opposite potential\npolarity was applied on semiconducting single-walled carbon nanotube and\nmolybdenum disulfide nanotube, respectively, the rectifying effect was\nmaterialized.",
        "positive": "Synthesis and characterization of ferromagnetic cobalt nanospheres,\n  nanodiscs and nanocubes: We report the synthesis of cobalt nanoparticles with different shapes and\nsizes by rapid pyrolysis of cobalt carbonyl in the presence of various\nsurfactants. The size and shape of the nanoparticles were influenced by\nreaction conditions, such as type of the surfactant, molar ratio of surfactant\nto precursor, reflux temperature and reaction time. The shapes that we have\nachieved include spherical, nearly spherical, disc and cube. The presence of\nlinear amine yielded nanodiscs and they spontaneously self-assembled into long\nribbons. The effect of shape anisotropy on magnetic nanoparticles has been\ninvestigated. Spherical nanoparticles of diameter 14.5 nm show strong\nferromagnetic behavior at low temperature and superparamagnetism at room\ntemperature. On the other hand the cubic nanoparticles of 45 nm sides showed\nnegligible coercive field at T = 10 K and ferromagnetism that persisted above T\n= 300 K. The cobalt nanospheres were oxidized to grow cobalt oxide shell of\nvarying thickness to study exchange bias effect. A pronounced exchange bias and\na strong temperature dependant magnetization were observed in oxidized cobalt\nnanospheres."
    },
    {
        "anchor": "Magnetoconductance of the Corbino disk in graphene: Chiral tunneling and\n  quantum interference in the bilayer case: Quantum transport through an impurity-free Corbino disk in bilayer graphene\nis investigated analytically, by the mode-matching method for effective Dirac\nequation, in the presence of uniform magnetic fields. Similarly as in the\nmonolayer case (see Refs. [1,2]), conductance at the Dirac point shows\noscillations with the flux piercing the disk area $\\Phi_D$ characterized by the\nperiod $\\Phi_0=2\\,(h/e)\\ln(R_{\\rm o}/R_{\\rm i})$, where $R_{\\rm o}$ ($R_{\\rm\ni}$) is the outer (inner) disk radius. The oscillations magnitude depends\neither on the radii ratio or on the physical disk size, with the condition for\nmaximal oscillations reading $R_{\\rm o}/R_{\\rm i}\\simeq\\left[\\,R_{\\rm\ni}t_{\\perp}/(2\\hbar{}v_{F})\\,\\right]^{4/p}$ (for $R_{\\rm o}/R_{\\rm i}\\gg{}1$),\nwhere $t_\\perp$ is the interlayer hopping integral, $v_F$ is the Fermi velocity\nin graphene, and $p$ is an {\\em even} integer. {\\em Odd}-integer values of $p$\ncorrespond to vanishing oscillations for the normal Corbino setup, or to\noscillations frequency doubling for the Andreev-Corbino setup. At higher Landau\nlevels (LLs) magnetoconductance behaves almost identically in the monolayer and\nbilayer cases. A brief comparison with the Corbino disk in 2DEG is also\nprovided in order to illustrate the role of chiral tunneling in graphene.",
        "positive": "Electronic energy state and transmission properties study of triple\n  barrier parabolic double quantum well: We investigate transmission properties of triple barrier parabolic double\nquantum well structure using the non-equilibrium Green's function method. In\nparticular, we examine the effect of system parameters on transmission\ncoefficient. The properties of the electronic state are also studied as a\nfunction of the system parameters (such as the well and barrier widths) and\nelectric field bias. We also tested energy electronic state with calculating\nthe density of states. It has been found that the first resonant peaks shift\ntowards the lower energy region as the middle barrier width increases. New\nresonant peaks emerge when the well widths or depths become wider. These\nstructures are useful for the design of electronic devices."
    },
    {
        "anchor": "Exact current-current Green functions in strongly correlated 1D systems\n  with impurity: We derive an exact expression for the Kubo conductunce in the Quantum Hall\ndevice with the point-like intra-edge backscattering. This involves the\ncalculation of current-current correlator exactly, which we perform using\nform-factor method. In brief, the full set of intermediate states is inserted\nin the correlator, and for each term the closed mathematical expression is\nobtained. It is shown that by making a special choice of intermediate states in\naccordance with the hidden symmetries of the model, one achieves fast\nconvergence of the series, thus proving the form-factor approach to be\nespecially powerfull. This review is based on the joint work with H.Saleur and\nF.Lesage.",
        "positive": "Collision-dominated nonlinear hydrodynamics in graphene: We present an effective hydrodynamic theory of electronic transport in\ngraphene in the interaction-dominated regime. We derive the emergent\nhydrodynamic description from the microscopic Boltzmann kinetic equation taking\ninto account dissipation due to Coulomb interaction and find the viscosity of\nDirac fermions in graphene for arbitrary densities. The viscous terms have a\ndramatic effect on transport coefficients in clean samples at high\ntemperatures. Within linear response, we show that viscosity manifests itself\nin the nonlocal conductivity as well as dispersion of hydrodynamic plasmons.\nBeyond linear response, we apply the derived nonlinear hydrodynamics to the\nproblem of hot spot relaxation in graphene."
    },
    {
        "anchor": "Nonlocality of Majorana Modes in Hybrid Nanowires: Spatial separation of Majorana zero modes distinguishes trivial from\ntopological midgap states and is key to topological protection in quantum\ncomputing applications. Although signatures of Majorana zero modes in tunneling\nspectroscopy have been reported in numerous studies, a quantitative measure of\nthe degree of separation, or nonlocality, of the emergent zero modes has not\nbeen reported. Here, we present results of an experimental study of nonlocality\nof emergent zero modes in superconductor-semiconductor hybrid nanowire devices.\nThe approach takes advantage of recent theory showing that nonlocality can be\nmeasured from splitting due to hybridization of the zero mode in resonance with\na quantum dot state at one end of the nanowire. From these splittings as well\nas anticrossing of the dot states, measured for even and odd occupied quantum\ndot states, we extract both the degree of nonlocality of the emergent zero\nmode, as well as the spin canting angles of the nonlocal zero mode. Depending\non the device measured, we obtain either a moderate degree of nonlocality,\nsuggesting a partially separated Andreev subgap state, or a highly nonlocal\nstate consistent with a well-developed Majorana mode.",
        "positive": "Spin-flop transition in atomically thin MnPS$_3$ crystals: The magnetic state of atomically thin semiconducting layered antiferromagnets\nsuch as CrI$_3$ and CrCl$_3$ can be probed by forming tunnel barriers and\nmeasuring their resistance as a function of magnetic field ($H$) and\ntemperature ($T$). This is possible because the tunneling magnetoresistance\noriginates from a spin-filtering effect sensitive to the relative orientation\nof the magnetization in different layers, i.e., to the magnetic state of the\nmultilayers. For systems in which antiferromagnetism occurs within an\nindividual layer, however, no spin-filtering occurs: it is unclear whether this\nstrategy can work. To address this issue, we investigate tunnel transport\nthrough atomically thin crystals of MnPS$_3$, a van der Waals semiconductor\nthat in the bulk exhibits easy-axis antiferromagnetic order within the layers.\nFor thick multilayers below $T\\simeq 78$ K, a $T$-dependent magnetoresistance\nsets-in at $\\sim 5$ T, and is found to track the boundary between the\nantiferromagnetic and the spin-flop phases known from bulk magnetization\nmeasurements. The magnetoresistance persists down to individual MnPS$_3$\nmonolayers with nearly unchanged characteristic temperature and magnetic field\nscales, albeit with a different dependence on $H$. We discuss the implications\nof these finding for the magnetic state of atomically thin MnPS$_3$ crystals,\nconclude that antiferromagnetic correlations persist down to the level of\nindividual monolayers, and that tunneling magnetoresistance does allow\nmagnetism in 2D insulating materials to be detected even in the absence of\nspin-filtering."
    },
    {
        "anchor": "A Spin Quintet in a Silicon Double Quantum Dot: Spin Blockade and\n  Relaxation: Spins in gate-defined silicon quantum dots are promising candidates for\nimplementing large-scale quantum computing. To read the spin state of these\nqubits, the mechanism that has provided the highest fidelity is spin-to-charge\nconversion via singlet-triplet spin blockade, which can be detected in-situ\nusing gate-based dispersive sensing. In systems with a complex energy spectrum,\nlike silicon quantum dots, accurately identifying when singlet-triplet blockade\noccurs is hence of major importance for scalable qubit readout. In this work,\nwe present a description of spin blockade physics in a tunnel-coupled silicon\ndouble quantum dot defined in the corners of a split-gate transistor. Using\ngate-based magnetospectroscopy, we report successive steps of spin blockade and\nspin blockade lifting involving spin states with total spin angular momentum up\nto $S=3$. More particularly, we report the formation of a hybridized spin\nquintet state and show triplet-quintet and quintet-septet spin blockade. This\nenables studies of the quintet relaxation dynamics from which we find $T_1 \\sim\n4 ~\\mu s$. Finally, we develop a quantum capacitance model that can be applied\ngenerally to reconstruct the energy spectrum of a double quantum dot including\nthe spin-dependent tunnel couplings and the energy splitting between different\nspin manifolds. Our results open for the possibility of using Si CMOS quantum\ndots as a tuneable platform for studying high-spin systems.",
        "positive": "Two-dimensional quantum walk with non-Hermitian skin effects: We construct a two-dimensional, discrete-time quantum walk exhibiting\nnon-Hermitian skin effects under open-boundary conditions. As a confirmation of\nthe non-Hermitian bulk-boundary correspondence, we show that the emergence of\ntopological edge states are consistent with Floquet winding numbers calculated\nusing a non-Bloch band theory invoking time-dependent generalized Billouin\nzones. Further, the non-Bloch topological invariants associated with\nquasienergy bands are captured by a non-Hermitian local Chern marker in real\nspace, defined through local biorthogonal eigen wave functions of the\nnon-unitary Floquet operator. Our work would stimulate further studies of\nnon-Hermitian Floquet topological phases where skin effects play a key role."
    },
    {
        "anchor": "Electron scattering on microscopic corrugations in graphene: We discuss various scattering mechanisms for Dirac fermions in single-layer\ngraphene. It is shown that scattering on a short-range potential (due to, for\nexample, neutral impurities) is mostly irrelevant for electronic quality of\ngraphene, which is likely to be controlled by charged impurities and ripples\n(microscopic corrugations of a graphene sheet). The latter are an inherent\nfeature of graphene due to its two-dimensional nature and can also be an\nimportant factor in defining the electron mean free path. We show that certain\ntypes of ripples create a long-range scattering potential, similar to Coulomb\nscatterers, and result in charge-carrier mobility practically independent on\ncarrier concentration, in agreement with experimental observations.",
        "positive": "Mesoscopic superconducting disks: Using the non-linear Ginzburg-Landau (GL) eqs. type I superconducting disks\nof finite radius ($R$) and thickness ($d$) are studied in a perpendicular\nmagnetic field. Depending on $R$ and $d$, first or second order phase\ntransitions are found for the normal to superconducting state. For sufficiently\nlarge $R$ several transitions in the superconducting phase are found\ncorresponding to different angular momentum giant vortex states. In increasing\nmagnetic field the superconductor is in its ground state, while in field down\nsweep it is possible to drive the system into metastable states. We also\npresent a quantitative analysis of the relation between the detector output and\nthe sample magnetization. The latter, and the incorporation of the finite\nthickness of the disks, are essential in order to obtain quantitative agreement\nwith experiment."
    },
    {
        "anchor": "High-temperature quantum oscillations caused by recurring Bloch states\n  in graphene superlattices: Cyclotron motion of charge carriers in metals and semiconductors leads to\nLandau quantization and magneto-oscillatory behavior in their properties.\nCryogenic temperatures are usually required to observe these oscillations. We\nshow that graphene superlattices support a different type of quantum\noscillations that do not rely on Landau quantization. The oscillations are\nextremely robust and persist well above room temperature in magnetic fields of\nonly a few T. We attribute this phenomenon to repetitive changes in the\nelectronic structure of superlattices such that charge carriers experience\neffectively no magnetic field at simple fractions of the flux quantum per\nsuperlattice unit cell. Our work points at unexplored physics in Hofstadter\nbutterfly systems at high temperatures.",
        "positive": "Observation of Protected Photonic Edge States Induced By Real-Space\n  Topological Lattice Defects: Topological defects (TDs) in crystal lattices are elementary lattice\nimperfections that cannot be removed by local perturbations, due to their real\nspace topology. We show that adding TDs into a valley photonic crystal\ngenerates a lattice disclination that acts like a domain wall and hosts\ntopological edge states. The disclination functions as a freeform waveguide\nconnecting a pair of TDs of opposite topological charge. This interplay between\nthe real-space topology of lattice defects and band topology provides a novel\nscheme to implement large-scale photonic structures with complex arrangements\nof robust topological waveguides and resonators."
    },
    {
        "anchor": "Splitting efficiency and interference effects in a Cooper pair splitter\n  based on a triple quantum dot with ferromagnetic contacts: We theoretically study the spin-resolved subgap transport properties of a\nCooper pair splitter based on a triple quantum dot attached to superconducting\nand ferromagnetic leads. Using the Keldysh Green's function formalism, we\nanalyze the dependence of the Andreev conductance, Cooper pair splitting\nefficiency, and tunnel magnetoresistance on the gate and bias voltages applied\nto the system. We show that the system's transport properties are strongly\naffected by spin dependence of tunneling processes and quantum interference\nbetween different local and nonlocal Andreev reflections. We also study the\neffects of finite hopping between the side quantum dots on the Andreev current.\nThis allows for identifying the optimal conditions for enhancing the Cooper\npair splitting efficiency of the device. We find that the splitting efficiency\nexhibits a nonmonotonic dependence on the degree of spin polarization of the\nleads and the magnitude and type of hopping between the dots. An almost perfect\nsplitting efficiency is predicted in the nonlinear response regime when the\nenergies of the side quantum dots are tuned to the energies of the\ncorresponding Andreev bound states. In addition, we analyzed features of the\ntunnel magnetoresistance (TMR) for a wide range of the gate and bias voltages,\nas well as for different model parameters, finding the corresponding sign\nchanges of the TMR in certain transport regimes. The mechanisms leading to\nthese effects are thoroughly discussed.",
        "positive": "Extended interface states enhance valley splitting in Si/SiO2: Interface disorder and its effect on the valley degeneracy of the conduction\nband edge remains among the greatest theoretical challenges for understanding\nthe operation of spin qubits in silicon. Here, we investigate a\ncounterintuitive effect occurring at Si/SiO2 interfaces. By applying tight\nbinding methods, we show that intrinsic interface states can hybridize with\nconventional valley states, leading to a large ground state energy gap. The\neffects of hybridization have not previously been explored in details for\nvalley splitting. We find that valley splitting is enhanced in the presence of\ndisordered chemical bonds, in agreement with recent experiments."
    },
    {
        "anchor": "Phonon angular momentum Hall effect: Spin Hall effect is the transverse flow of the electron spin in conductors\nunder external electric field. Similarly, thermal gradient in magnetic\ninsulators can drive a transverse flow of the spin angular momentum of magnons,\nwhich provides a thermal alternative for spin manipulation. Recently, the\nphonon angular momentum (PAM), which is the angular momentum of atoms as a\nresult of their orbital motion around their equilibrium positions, has garnered\nattention as a quantity analogous to the magnon spin. However, can we\nmanipulate PAM like magnon spin? Here, we show that temperature gradient\ngenerally induces a transverse flow of PAM, which we term the phonon angular\nmomentum Hall effect (PAMHE). The PAMHE relies only on the presence of\ntransverse and longitudinal acoustic phonons, and it is therefore ubiquitous in\ncondensed matter systems. As a consequence of the PAMHE, PAM accumulates at the\nedges of a crystal. When the atoms in the crystal carry nonzero Born effective\ncharge, the edge PAM induces edge magnetization, which may be observed through\noptical measurement. We believe that PAMHE provides a new principle for the\nmanipulation of angular momenta in insulators and opens up an avenue for\ndeveloping functional materials based on phonon engineering.",
        "positive": "Critical Field of Spin Torque Oscillator with Perpendicularly Magnetized\n  Free Layer: The oscillation properties of a spin torque oscillator consisting of a\nperpendicularly magnetized free layer and an in-plane magnetized pinned layer\nare studied based on an analysis of the energy balance between spin torque and\ndamping. The critical value of an external magnetic field applied normal to the\nfilm plane is found, below which the controllable range of the oscillation\nfrequency by the current is suppressed. The value of the critical field depends\non the magnetic anisotropy, the saturation magnetization, and the spin torque\nparameter."
    },
    {
        "anchor": "Hamiltonian theory of fractionally filled Chern bands: There is convincing numerical evidence that fractional quantum Hall\n(FQH)-like ground states arise in fractionally filled Chern bands (FCB). Here\nwe show that the Hamiltonian theory of Composite Fermions (CF) can be as useful\nin describing the FCB as it was in describing the FQHE in the continuum. We are\nable to introduce CFs into the FCB problem even though there is no external\nmagnetic field by following a two-stage process. First we construct an\nalgebraically exact mapping which expresses the electron density projected to\nthe Chern band, ${\\rho}_{{\\tiny FCB}}$, as a sum of Girvin-MacDonald-Platzman\ndensity operators, ${\\rho}_{{\\tiny GMP}}$, that obey the Magnetic Translation\nAlgebra. Next, following our Hamiltonian treatment of the FQH problem, we\nrewrite the GMP operators in terms of CF variables which reproduce the same\nalgebra. This naturally produces a unique Hartree-Fock ground state for the\nCFs, which can be used as a springboard for computing gaps, response functions,\ntemperature-dependent phenomena, and the influence of disorder. We give two\nconcrete examples, one of which has no analog in the continuum FQHE with $\\nu=\n{1 \\over 5}$ and $\\sigma_{xy}={2\\over 5}$. Our approach can be easily extended\nto fractionally filled, strongly interacting two-dimensional\ntime-reversal-invariant topological insulators.",
        "positive": "The 3D transport diagram of a triple quantum dot: We measure a triple quantum dot in the regime where three addition lines,\ncorresponding to the addition of an electron to each of three dots, pass\nthrough each other. In particular, we probe the interplay between transport and\nthe tridimensional nature of the stability diagram. We choose the regime most\npertinent for spin qubit applications. We find that at low bias transport\nthrough the triple quantum dot circuit is only possible at six quadruple point\nlocations. The results are consistent with an equivalent circuit model."
    },
    {
        "anchor": "Coulomb blockade in graphene nanoribbons: We propose that recent transport experiments revealing the existence of an\nenergy gap in graphene nanoribbons may be understood in terms of Coulomb\nblockade. Electron interactions play a decisive role at the quantum dots which\nform due to the presence of necks arising from the roughness of the graphene\nedge. With the average transmission as the only fitting parameter, our theory\nshows good agreement with the experimental data.",
        "positive": "Noise and microresonance of critical current in Josephson junction\n  induced by Kondo trap states: We analyze the impact of trap states in the oxide layer of a superconducting\ntunnel junctions, on the fluctuation of the Josephson critical current, thus on\ncoherence in superconducting qubits. Two mechanisms are usually considered: the\ncurrent blockage due to repulsion at the occupied trap states, and the noise\nfrom electrons hopping across a trap. We extend previous studies of\nnoninteracting traps to the case where the traps have on-site electron\nrepulsion inside one ballistic channel. The repulsion not only allows the\nappropriate temperature dependence of 1/f noise, but also is a control to the\ncoupling between the computational qubit and the spurious two-level systems\ninside the oxide dielectric. We use second order perturbation theory which\nallows to obtain analytical formulae for the interacting bound states and\nspectral weights, limited to small and intermediate repulsions. Remarkably, it\nstill reproduces the main features of the model as identified from the\nNumerical Renormalization Group. We present analytical formulations for the\nsubgap bound state energies, the singlet-doublet phase boundary, and the\nspectral weights. We show that interactions can reverse the supercurrent across\nthe trap. We finally work out the spectrum of junction resonators for qubits in\nthe presence of on-site repulsive electrons and analyze its dependence on\nmicroscopic parameters that may be controlled by fabrication."
    },
    {
        "anchor": "Physical electrostatics of small field emitter arrays/clusters: This paper improves understanding of electrostatic influences on apex field\nenhancement factors (AFEFs) for small field emitter arrays. Using the \"floating\nsphere at emitter-plate potential\" (FSEPP) model, it re-examines the\nelectrostatics and mathematics of three simple systems of identical post-like\nemitters. For the isolated emitter, various approaches are noted. On need\nconsider only the effects of sphere charges and (for separated emitters) image\ncharges. For the 2-emitter system, formulas are found for \"charge-blunting\" and\n\"neighbour-field\" effects, for widely spaced and \"sufficiently closely spaced\"\nemitters. Mutual charge-blunting is always dominant, with a related (negative)\nfractional AFEF-change {\\delta}_two. For sufficiently small emitter spacing c,\n|{\\delta}_two| varies as 1/c; for large spacing, |{\\delta}_two| decreases as\n1/c^3. In a 3-emitter linear array, differential charge-blunting and\ndifferential neighbor-field effects occur, but the former are dominant, and\ncause the \"exposed\" outer emitters to have higher AFEF ({\\gamma}_0) than the\ncentral emitter ({\\gamma}_1). Formulas are found for the exposure ratio\n{\\Xi}={\\gamma}_0/{\\gamma}_1, for large and for sufficiently small separations.\nThe FSEPP model for an isolated emitter has accuracy around 30%. Line-charge\nmodels (LCMs) are an alternative, but an apparent difficulty with recent LCM\nmodels is identified. Better descriptions of array electrostatics may involve\ndeveloping good fitting equations for AFEFs derived from accurate numerical\nsolution of Laplace's equation, perhaps with equation form(s) guided\nqualitatively by FSEPP-model results. In existing fitting formulas, the\nAFEF-reduction decreases exponentially as c increases, which differs from\nFSEPP-model formulas. FSEPP models might provide a useful guide to the\nqualitative behaviour of small field emitter clusters larger than those\ninvestigated.",
        "positive": "Interplay between Kondo and Andreev-Josephson effects in a quantum dot\n  coupled to one normal and two superconducting leads: We study low-energy transport through a quantum dot coupled to one normal and\ntwo superconducting (SC) leads in a junction of Y-shape. In this geometry a\ncrossover between Kondo dominated and Cooper-pairing dominated states occurs by\ntuning the parameters such as the quantized energy level of the dot and the\nJosephson phase, which induces a supercurrent flowing between the two SC leads\nthrough the dot. Furthermore, Andreev scattering takes place at the interface\nbetween the dot and normal lead. The low-lying energy states of this system can\nbe described by a local Fermi-liquid theory for interacting Bogoliubov\nparticles. In a description based on an Anderson impurity model we calculate\ntransport coefficients, renormalized parameters and spectral function, using\nWilson's numerical renormalization group (NRG) approach, in the limit of large\nSC gap. Our results demonstrate how the Andreev resonance level approaches the\nFermi level in the crossover region between Cooper-pairing singlet state and\nstrong coupling situation as the impurity level or Josephson phase are varied.\nThe strong coupling situation shows a Kondo effect with a significantly\nrenormalized resonance width. The crossover is smeared when the coupling\nbetween the dot and normal lead is large. Furthermore, asymmetry in the\nJosephson junction suppresses the cancellations of the SC proximity for finite\nJosephson phase, and it favors the SC singlet state rather than the Kondo\nsinglet."
    },
    {
        "anchor": "Ultrafast excitation and topological soliton formation in incommensurate\n  charge density wave states: Topological soliton is a nonperturbative excitation in commensurate density\nwave states and connects degenerate ground states. In incommensurate density\nwave states, ground states are continuously degenerate and topological soliton\nis reckoned to be smoothly connected to the perturbative phason excitation. We\nstudy the ultrafast nonequilibrium dynamics due to photoexcited electron-hole\npair in a one-dimensional chain with an incommensurate charge density wave\nground state. Time-resolved evolution reveals both perturbative excitation of\ncollective modes and nonperturbative topological phase transition due to\ncreating novel topological solitons, where the continuous complex order\nparameter with amplitude and phase is essential. We identify the nontrivial\nphase-winding solitons in the complex plane unique to this nonequilibrium state\nand capture it by a low-energy effective model. The perturbative temporal gap\noscillation and the solitonic in-gap states enter the optical conductivity\nabsorption edge and the spectral density related to spectroscopic measurement,\nproviding concrete connections to real experiments.",
        "positive": "Probing Interband Coulomb Interactions in Semiconductor Nanocrystals\n  with 2D Double-Quantum Coherence Spectroscopy: Using previously developed exciton scattering model accounting for the\ninterband, i.e., exciton-biexciton, Coulomb interactions in semiconductor\nnanocrystals (NCs), we derive a closed set of equations for 2D double-quantum\ncoherence signal. The signal depends on the Liouville space pathways which\ninclude both the interband scattering processes and the inter- and intraband\noptical transitions. These processes correspond to the formation of different\ncross-peaks in the 2D spectra. We further report on our numerical calculations\nof the 2D signal using reduced level scheme parameterized for PbSe NCs. Two\ndifferent NC excitation regimes considered and unique spectroscopic features\nassociated with the interband Coulomb interactions are identified."
    },
    {
        "anchor": "Boundary conditions and Green function approach of the spin-orbit\n  interaction in the graphitic nanocone: The boundary effects affecting the Hamiltonian for the nanocone with\ncurvatureinduced spin orbit coupling were considered and the corresponding\nelectronic structure was calculated. These boundary effects include the spin\norbit coupling, the electron mass acquisition and the Coulomb interaction.\nDifferent numbers of the pentagonal defects in the tip were considered. The\nGreen function approach into the second order was used for getting more precise\nresults in the case of the spin orbit coupling.",
        "positive": "Quantum confined electronic states in atomically well-defined graphene\n  nanostructures: Despite the enormous interest in the properties of graphene and the potential\nof graphene nanostructures in electronic applications, the study of quantum\nconfined states in atomically well-defined graphene nanostructures remains an\nexperimental challenge. Here, we study graphene quantum dots (GQDs) with\nwell-defined edges in the zigzag direction, grown by chemical vapor deposition\n(CVD) on an iridium(111) substrate, by low-temperature scanning tunneling\nmicroscopy (STM) and spectroscopy (STS). We measure the atomic structure and\nlocal density of states (LDOS) of individual GQDs as a function of their size\nand shape in the range from a couple of nanometers up to ca. 20 nm. The results\ncan be quantitatively modeled by a relativistic wave equation and atomistic\ntight-binding calculations. The observed states are analogous to the solutions\nof the text book \"particle-in-a-box\" problem applied to relativistic massless\nfermions."
    },
    {
        "anchor": "Towards a theory of surface orbital magnetization: The theory of bulk orbital magnetization has been formulated both in\nreciprocal space based on Berry curvature and related quantities, and in real\nspace in terms of the spatial average of a quantum mechanical local marker.\nHere we consider a three-dimensional antiferromagnetic material having a\nvanishing bulk but a nonzero surface orbital magnetization. We ask whether the\nsurface-normal component of the surface magnetization is well defined, and if\nso, how to compute it. As the physical observable corresponding to this\nquantity, we identify the macroscopic current running along a hinge shared by\ntwo facets. However, the hinge current only constrains the difference of the\nsurface magnetizations on the adjoined facets, leaving a potential ambiguity.\nBy performing a symmetry analysis, we find that only crystals exhibiting a\npseudoscalar symmetry admit well-defined magnetizations at their surfaces at\nthe classical level. We then explore the possibility of computing surface\nmagnetization via a coarse-graining procedure applied to a quantum local\nmarker. We show that multiple expressions for the local marker exist, and apply\nconstraints to filter out potentially meaningful candidates. Using several\ntight-binding models as our theoretical test bed and several potential markers,\nwe compute surface magnetizations for slab geometries and compare their\npredictions with explicit calculations of the macroscopic hinge currents of rod\ngeometries. We find that only a particular form of the marker consistently\npredicts the correct hinge currents.",
        "positive": "Topological spin torque emerging in classical-spin systems with\n  different time scales: In classical spin systems with two largely different inherent time scales,\nthe configuration of the fast spins almost instantaneously follows the\nslow-spin dynamics. We develop the emergent effective theory for the slow-spin\ndegrees of freedom and demonstrate that this generally includes a topological\nspin torque. This torque gives rise to anomalous real-time dynamics. It derives\nfrom the holonomic constraints defining the fast-spin configuration space and\nis given in terms of a topological charge density which becomes a quantized\nhomotopy invariant when integrated."
    },
    {
        "anchor": "Modeling the Oblique Spin Precession in Lateral Spin Valves for Accurate\n  Determination of Spin Lifetime Anisotropy: Effect of Finite Contact\n  Resistance and Channel Length: The spin lifetime anisotropy is an important quantity for investigating the\nspin relaxation mechanisms in graphene and in heterostructures of\ntwo-dimensional materials. We generalize the diffusive spin transport equations\nof oblique spin precession in a lateral spin valve with finite contact\nresistance. This yields a method to determine the spin lifetime anisotropy\nratio {\\xi}={\\tau}$_{\\perp}$/{\\tau}$_{\\parallel}$, which is the ratio between\nlifetimes of spin polarized perpendicular and parallel to the graphene surface.\nBy solving the steady-state Bloch equations, we show that the line-shape of the\noblique spin precession signal can be described with six dimensionless\nparameters, which can be solved analytically. We demonstrate that the\nanisotropic spin precession characteristics can be strongly suppressed by\ncontact induced spin relaxation originating from conductance mismatch between\nthe channel material and electrodes. To extract the spin lifetime anisotropy\nratio accurately, we develop a closed form equation that includes the effect of\nfinite contact resistance. Furthermore, we demonstrate that in the high contact\nresistance regime, the minimum channel length required for accurately\ndetermining the spin lifetime anisotropy for a sufficiently low external\nmagnetic field is only determined by the diffusion coefficient of the channel\nmaterial, as opposed to the spin diffusion length. Our work provides an\naccurate model to extract the spin lifetime anisotropy ratio from the oblique\nspin precession measurement, and can be used to guide the device design for\nsuch measurements.",
        "positive": "Near-threshold properties of the electronic density of layered\n  quantum-dots: We present a way to manipulate an electron trapped in a layered quantum dot\nbased on near-threshold properties of one-body potentials. We show that\npotentials with a simple global parameter allows the manipulation of the wave\nfunction changing its spatial extent. This phenomenon seems to be fairly\ngeneral and could be implemented using current quantum-dot quantum wells\ntechnologies and materials if a proper layered quantum dot is designed. The\nlayered quantum dot under consideration is similar to a quantum-dot quantum\nwell device, i.e. consists of a spherical core surrounded by successive layers\nof different materials. The number of layers and the constituent material are\nchosen to highlight the near-threshold properties.\n  In particular we show that the near-threshold phenomena can be observed using\nan effective mass approximation model that describes the layered quantum dot\nwhich is consistent with actual experimental parameters."
    },
    {
        "anchor": "Quantum calculations of the carrier mobility in thin films: Methodology,\n  Matthiessen's rule and comparison with semi-classical approaches: We discuss the calculation of the carrier mobility in silicon films within\nthe quantum Non-Equilibrium Green's Functions (NEGF) framework. We introduce a\nnew method for the extraction of the carrier mobility that is free from contact\nresistance contamination, and provides accurate mobilities at a reasonable\ncost, with minimal needs for ensemble averages. We then introduce a new\nparadigm for the definition of the partial mobility $\\mu_{M}$ associated with a\ngiven elastic scattering mechanism \"M\", taking phonons (PH) as a reference\n($\\mu_{M}^{-1}=\\mu_{PH+M}^{-1}-\\mu_{PH}^{-1}$). We argue that this definition\nmakes better sense in a quantum transport framework as it is free from long\nrange interference effects that can appear in purely ballistic calculations. As\na matter of fact, these mobilities satisfy Matthiessen's rule for three\nmechanisms [surface roughness (SR), remote Coulomb scattering (RCS) and\nphonons] much better than the usual, single mechanism calculations. We also\ndiscuss the problems raised by the long range spatial correlations in the RCS\ndisorder. Finally, we compare semi-classical Kubo-Greenwood (KG) and quantum\nNEGF calculations. We show that KG and NEGF are in reasonable agreement for\nphonon and RCS, yet not for SR. We point to possible deficiencies in the\ntreatment of SR scattering in KG, opening the way for further improvements.",
        "positive": "Electromagnetic Field Correlation inside a Sonoluminescing Bubble: We consider the correlation of the electromagnetic field to determine spatial\ncoherence inside a sonoluminescing bubble. We explicitly calculate the first\norder correlation function for two limiting cases of the excitation field: a\nblackbody spectrum and a discrete multifrequency spectrum. The correlation\nlength for blackbody fields at temperatures between 3000 K and 10000 K is found\nto be on the order of the optical wavelength, increasing with decreasing\ntemperatures. We predict spectral lines in the emission spectrum of single\nbubble sonoluminescence in cooler bubbles with interior temperatures below\n10000 K."
    },
    {
        "anchor": "Moir\u00e9-less Correlations in ABCA Graphene: Atomically thin van der Waals materials stacked with an interlayer twist have\nproven to be an excellent platform towards achieving gate-tunable correlated\nphenomena linked to the formation of flat electronic bands. In this work we\ndemonstrate the formation of emergent correlated phases in multilayer\nrhombohedral graphene - a simple material that also exhibits a flat electronic\nband but without the need of having a moir\\'e superlattice induced by twisted\nvan der Waals layers. We show that two layers of bilayer graphene that are\ntwisted by an arbitrary tiny angle host large (micron-scale) regions of uniform\nrhombohedral four-layer (ABCA) graphene that can be independently studied.\nScanning tunneling spectroscopy reveals that ABCA graphene hosts an\nunprecedentedly sharp flat band of 3-5 meV half-width. We demonstrate that when\nthis flat band straddles the Fermi level, a correlated many-body gap emerges\nwith peak-to-peak value of 9.5 meV at charge neutrality. Mean field theoretical\ncalculations indicate that the two primary candidates for the appearance of\nthis broken symmetry state are a charge transfer excitonic insulator and a\nferrimagnet. Finally, we show that ABCA graphene hosts surface topological\nhelical edge states at natural interfaces with ABAB graphene which can be\nturned on and off with gate voltage, implying that small angle twisted double\nbilayer graphene is an ideal programmable topological quantum material.",
        "positive": "Quantum Anomalous Hall Insulator of Composite Fermions: We show that a weak hexagonal periodic potential could transform a\ntwo-dimensional electron gas with an even-denominator magnetic filling factor\nto a quantum anomalous Hall insulator of composite fermions, giving rise to\nfractionally quantized Hall effect. The system provides a realization of the\nHaldane honeycomb-net model, albeit in a composite fermion system. We further\npropose a trial wave function for the state, and numerically evaluate its\nrelative stability against the competing Hofstadter state. Possible sets of\nexperimental parameters are proposed."
    },
    {
        "anchor": "Spin noise in a quantum dot ensemble: from a quantum mechanical to a\n  semi-classical description: Spin noise spectroscopy is a promising technique for revealing the\nmicroscopic nature of spin dephasing processes in quantum dots. We compare the\nspin-noise in an ensemble of singly charged quantum dots calculated by two\ncomplementary approaches. The Chebyshev polynomial expansion technique (CET)\naccounts for the full quantum mechanical fluctuation of the nuclear spin bath\nand a semi-classical approach (SCA) is based on the averaging the electron spin\ndynamics over all different static Overhauser field configurations.\n  We observe a remarkable agreement between both methods in the high-frequency\npart of the spectra, while the low-frequency part is determined by the long\ntime fluctuations of the Overhauser field. We find small differences in the\nspectra depending on the distribution of hyperfine couplings. The spin-noise\nspectra in strong enough magnetic fields where the nuclear dynamics is quenched\ncalculated by two complimentary approaches are in perfect agreement.",
        "positive": "Aharonov-Bohm Effect in Concentric Quantum Double Rings: We propose a theoretical model to study the single-electron spectra of the\nconcentric quantum double ring fabricated lately by self-assembled technique.\nExact diagonalization method is employed to examine the Aharonov-Bohm effect in\nthe concentric double ring. It is found the appearance of the AB oscillation in\ntotal energy depends on the strength of the screened potential. Variations of\nthe energy spectra with the presence of coulomb impurities located at inner or\nouter ring are also investigated."
    },
    {
        "anchor": "Lasing of Moir\u00e9 Trapped MoSe$_2$/WSe$_2$ Interlayer Excitons Coupled\n  to a Nanocavity: Moir\\'e trapped interlayer excitons (IXs) in heterobilayer transition metal\ndichalcogenides currently attract strong interest due to their potential for\nnon-classical light generation, coherent spin-photon interfaces and exploring\nnovel correlated phases of electrons. Here, we report lasing of moir\\'e trapped\nIXs by integrating a pristine hBN-encapsulated MoSe$_2$/WSe$_2$ heterobilayer\nin a high-Q ($>10^4$) nanophotonic cavity. We control the detuning between the\nIX line and the cavity mode with a magnetic field and measure the dipolar\ncoupling strength to the cavity mode to be $78 \\pm 4\\ \\mathrm{\\mu eV}$, fully\nconsistent with the $82\\ \\mathrm{\\mu eV}$ predicted by theory. The emission\nfrom the cavity mode shows clear threshold-like behaviour. We observe a\nsuperlinear power dependence accompanied by a narrowing of the linewidth as the\ndistinct features of lasing. The onset and prominence of these threshold-like\nbehaviours are significant at resonance whilst weak off-resonance. Our results\nshow that a lasing transition can be induced in interacting moir\\'e trapped IXs\nwith macroscopic coherence extending over the lengthscale of the cavity mode.\nSuch systems raise interesting perspectives for low-power switching and\nsynaptic nanophotonic devices using 2D materials.",
        "positive": "Electrostatics of straight and bent nanotubes: Response of a single-walled carbon nanotube to external electric field, F, is\ncalculated analytically within the classical electrostatics. Field-induced\ncharge density distribution is approximately linear along the axis of metallic\nnanotube and depends rather weakly, as ln(h/r), on the nanotube length, h,\n(here r is the nanotube radius). In a semiconducting nanotube with a gap, E_g,\ncharge separation occurs as F exceeds the threshold value F_{th}=E_g/eh. For\nF>F_{th}, positively and negatively charged regions at the ends of nanotube are\nseparated by a neutral strip in the middle. For bent nanotubes the number of\nneutral strips can be one or two depending on the direction of F."
    },
    {
        "anchor": "Surface-induced near-field scaling in the Knudsen layer of a rarefied\n  gas: We report on experiments performed within the Knudsen boundary layer of a\nlow-pressure gas. The non-invasive probe we use is a suspended\nnano-electro-mechanical string (NEMS), which interacts with $^4$He gas at\ncryogenic temperatures. When the pressure $P$ is decreased, a reduction of the\ndamping force below molecular friction $\\propto P$ had been first reported in\nPhys. Rev. Lett. Vol 113, 136101 (2014) and never reproduced since. We\ndemonstrate that this effect is independent of geometry, but dependent on\ntemperature. Within the framework of kinetic theory, this reduction is\ninterpreted as a rarefaction phenomenon, carried through the boundary layer by\na deviation from the usual Maxwell-Boltzmann equilibrium distribution induced\nby surface scattering. Adsorbed atoms are shown to play a key role in the\nprocess, which explains why room temperature data fail to reproduce it.",
        "positive": "Room-temperature Strong Coupling of Au Nanorod-WSe2 Heterostructures: All-solid-state strong light-matter coupling systems with large vacuum Rabi\nsplitting are great important for quantum information application, such as\nquantum manipulation, quantum information storage and processing. The monolayer\ntransition metal dichalcogenides (TMDs) have been explored as excellent\ncandidates for the strong light-matter interaction, due to their extraordinary\nexciton binding energies and remarkable optical properties. Here, for both of\nexperimental and theoretical aspects, we explored resonance coupling effect\nbetween exciton and plasmonic nanocavity in heterostructures consisting of\nmonolayer tungsten diselenide (WSe2) and an individual Au nanorod. We also\nstudy the influences on the resonance coupling of various parameters, including\nlocalized surface plasmon resonances of Au nanorods with varied topological\naspects, separation between Au nanorod and monolayer WSe2 surface, and the\nthickness of WSe2. More importantly, the resonance coupling can approach the\nstrong coupling regime at room-temperature by selecting appropriate parameters,\nwhere an anti-crossing behavior with the vacuum Rabi splitting strength of 98\nmeV was observed on the energy diagram."
    },
    {
        "anchor": "Engineering Hybrid Epitaxial InAsSb/Al Nanowire Materials for Stronger\n  Topological Protection: The combination of strong spin-orbit coupling, large $g$-factors, and the\ncoupling to a superconductor can be used to create a topologically protected\nstate in a semiconductor nanowire. Here we report on growth and\ncharacterization of hybrid epitaxial InAsSb/Al nanowires, with varying\ncomposition and crystal structure. We find the strongest spin-orbit interaction\nat intermediate compositions in zincblende InAs$_{1-x}$Sb$_{x}$ nanowires,\nexceeding that of both InAs and InSb materials, confirming recent theoretical\nstudies \\cite{winkler2016topological}. We show that the epitaxial InAsSb/Al\ninterfaces allows for a hard induced superconducting gap and 2$e$ transport in\nCoulomb charging experiments, similar to experiments on InAs/Al and InSb/Al\nmaterials, and find measurements consistent with topological phase transitions\nat low magnetic fields due to large effective $g$-factors. Finally we present a\nmethod to grow pure wurtzite InAsSb nanowires which are predicted to exhibit\neven stronger spin-orbit coupling than the zincblende structure.",
        "positive": "Quantum Lattice Contraction Induced by Transient Raman Process: The lattice contraction phenomenon found in time resolved X-ray diffraction\nand electron diffraction experiments is usually considered to be caused by\nphoto-generated carriers. However, the quantum calculation under finite-time\nboundary conditions leads to a transient Raman process that directly connects\noptical transitions and lattice displacements. The lattice contraction\nphenomenon and the coherent phonon phenomenon can be explained well by the\nprocess."
    },
    {
        "anchor": "Shot noise of the edge transport in the inverted band HgTe quantum wells: We investigate the current noise in HgTe-based quantum wells with an inverted\nband structure in the regime of disordered edge transport. Consistent with\nprevious experiments, the edge resistance strongly exceeds $h/e^2$ and weakly\ndepends on the temperature. The shot noise is well below the Poissonian value\nand characterized by the Fano factor with gate voltage and sample to sample\nvariations in the range $0.1<F<0.3$. Given the fact that our devices are\nshorter than the most pessimistic estimate of the ballistic dephasing length,\nthese observations exclude the possibility of one-dimensional helical edge\ntransport. Instead, we suggest that a disordered multi-mode conduction is\nresponsible for the edge transport in our experiment.",
        "positive": "Detecting Majorana fermions by nonlocal entanglement between quantum\n  dots: Nonlocal entanglement between two quantum dots can be generated through\nMajorana fermions. The two Majorana fermions at the ends of an one-dimensional\ntopological superconductor form a nonlocal fermion level, coupling to the\noccupation states of two quantum dots put close to the two ends, and the entire\nsystem will come into an entangled state. After introducing a charging energy\nby a capacitor, entanglement of the entire system can manifest itself through\nthe nonlocal entanglement between the two quantum dots. That is, when measuring\nthe electron occupations of the quantum dots, the measurement result of one\nquantum dot will influence the measurement result of the other quantum dot.\nThis nonlocal entanglement between the two quantum dots is a strong evidence of\nthe nonlocal nature of the fermion level constructed by two Majorana fermions."
    },
    {
        "anchor": "Radio-frequency-driven motion of single Cooper pairs across the\n  superconducting single-electron transistor with dissipative environment: We report on the effect of the frequency-locked transfer of single Cooper\npairs in a superconducting single-electron Al transistor embedded in a\ndissipative environment (on-chip Cr resistor of R = 40 kOhm). The transistor\nwas dc voltage biased, and the harmonic signal of frequency f of several MHz\nwas applied to the gate. Due to the substantial rate of relaxation, the\nunidirectional transfer of single pairs occurred in each junction once per\nclock cycle and the current plateaus at I = 2ef were developed in the\ntransistor's I-V curves. The mechanisms (supercurrent, Landau-Zener tunneling,\nquasiparticle tunneling, etc.) deteriorating the phase-locking regime are\ndiscussed.",
        "positive": "Surface state dominated spin-charge current conversion in topological\n  insulator/ferromagnetic insulator heterostructures: We report the observation of ferromagnetic resonance-driven spin pumping\nsignals at room temperature in three-dimensional topological insulator thin\nfilms -- Bi2Se3 and (Bi,Sb)2Te3 -- deposited by molecular beam epitaxy on\nyttrium iron garnet thin films. By systematically varying the Bi2Se3 film\nthickness, we show that the spin-charge conversion efficiency, characterized by\nthe inverse Rashba-Edelstein effect length (lambda_IREE), increases\ndramatically as the film thickness is increased from 2 quintuple layers,\nsaturating above 6 quintuple layers. This suggests a dominant role of surface\nstates in spin and charge interconversion in topological insulator/ferromagnet\nheterostructures. Our conclusion is further corroborated by studying a series\nof YIG/(BiSb)2Te3 heterostructures. Finally, we use the ferromagnetic resonance\nlinewidth broadening and the inverse Rashba-Edelstein signals to determine the\neffective interfacial spin mixing conductance and lambda_IREE."
    },
    {
        "anchor": "Electron heating in metallic resistors at sub-Kelvin temperature: In the presence of Joule heating, the electronic temperature in a metallic\nresistor placed at sub-Kelvin temperatures can significantly exceed the phonon\ntemperature. Electron cooling proceeds mainly through two processes: electronic\ndiffusion to and from the connecting wires and electron-phonon coupling. The\ngoal of this paper is to present a general solution of the problem, in a form\nthat can easily be used in practical situations. As an application, we compute\ntwo quantities that depend on the electronic temperature profile: the second\nand the third cumulant of the current noise at zero frequency, as a function of\nthe voltage across the resistor. We also consider time dependent heating, an\nissue relevant for experiments in which current pulses are used, for instance\nin time-resolved calorimetry experiments.",
        "positive": "Effect of electron-electron interaction on the phonon-mediated spin\n  relaxation in quantum dots: We estimate the spin relaxation rate due to spin-orbit coupling and acoustic\nphonon scattering in weakly-confined quantum dots with up to five interacting\nelectrons. The Full Configuration Interaction approach is used to account for\nthe inter-electron repulsion, and Rashba and Dresselhaus spin-orbit couplings\nare exactly diagonalized. We show that electron-electron interaction strongly\naffects spin-orbit admixture in the sample. Consequently, relaxation rates\nstrongly depend on the number of carriers confined in the dot. We identify the\nmechanisms which may lead to improved spin stability in few electron (>2)\nquantum dots as compared to the usual one and two electron devices. Finally, we\ndiscuss recent experiments on triplet-singlet transitions in GaAs dots subject\nto external magnetic fields. Our simulations are in good agreement with the\nexperimental findings, and support the interpretation of the observed spin\nrelaxation as being due to spin-orbit coupling assisted by acoustic phonon\nemission."
    },
    {
        "anchor": "Strong light-matter interaction in systems described by a modified Dirac\n  equation: The bulk states of some materials, such as topological insulators, are\ndescribed by a modified Dirac equation. Such systems may have trivial and\nnon-trivial phases. In this paper, we show that in the non-trivial phase a\nstrong light-matter interaction exists in a two-dimensional system, which leads\nto an optical conductivity at least one order of magnitude larger than that of\ngraphene.",
        "positive": "Magnetoresistance through a single molecule: The use of single molecules to design electronic devices is an extremely\nchallenging and fundamentally different approach to further downsizing\nelectronic circuits. Two-terminal molecular devices such as diodes were first\npredicted [1] and, more recently, measured experimentally [2]. The addition of\na gate then enabled the study of molecular transistors [3-5]. In general terms,\nin order to increase data processing capabilities, one may not only consider\nthe electron's charge but also its spin [6,7]. This concept has been pioneered\nin giant magnetoresistance (GMR) junctions that consist of thin metallic films\n[8,9]. Spin transport across molecules, i.e. Molecular Spintronics remains,\nhowever, a challenging endeavor. As an important first step in this field, we\nhave performed an experimental and theoretical study on spin transport across a\nmolecular GMR junction consisting of two ferromagnetic electrodes bridged by a\nsingle hydrogen phthalocyanine (H2Pc) molecule. We observe that even though\nH2Pc in itself is nonmagnetic, incorporating it into a molecular junction can\nenhance the magnetoresistance by one order of magnitude to 52%."
    },
    {
        "anchor": "Self-aligned local electrolyte gating of 2D materials with nanoscale\n  resolution: In the effort to make 2D materials-based devices smaller, faster, and more\nefficient, it is important to control charge carrier at lengths approaching the\nnanometer scale. Traditional gating techniques based on capacitive coupling\nthrough a gate dielectric cannot generate strong and uniform electric fields at\nthis scale due to divergence of the fields in dielectrics. This field\ndivergence limits the gating strength, boundary sharpness, and pitch size of\nperiodic structures, and restricts possible geometries of local gates (due to\nwire packaging), precluding certain device concepts, such as plasmonics and\ntransformation optics based on metamaterials. Here we present a new gating\nconcept based on a dielectric-free self-aligned electrolyte technique that\nallows spatially modulating charges with nanometer resolution. We employ a\ncombination of a solid-polymer electrolyte gate and an ion-impenetrable\ne-beam-defined resist mask to locally create excess charges on top of the gated\nsurface. Electrostatic simulations indicate high carrier density variations of\n$\\Delta n =10^{14}\\text{cm}^{-2}$ across a length of 10 nm at the mask\nboundaries on the surface of a 2D conductor, resulting in a sharp depletion\nregion and a strong in-plane electric field of $6\\times10^8 \\text{Vm}^{-1}$\nacross the so-created junction. We apply this technique to the 2D material\ngraphene to demonstrate the creation of tunable p-n junctions for\noptoelectronic applications. We also demonstrate the spatial versatility and\nself-aligned properties of this technique by introducing a novel graphene\nthermopile photodetector.",
        "positive": "Semiclassical theory of the emission properties of wave-chaotic resonant\n  cavities: We develop a perturbation theory for the lifetime and emission intensity for\nisolated resonances in asymmetric resonant cavities. The inverse lifetime\n$\\Gamma$ and the emission intensity $I(\\theta)$ in the open system are\nexpressed in terms of matrix elements of operators evaluated with eigenmodes of\nthe closed resonator. These matrix elements are calculated in a semiclassical\napproximation which allows us to represent $\\Gamma$ and $I(\\theta)$ as sums\nover the contributions of rays which escape the resonator by refraction."
    },
    {
        "anchor": "Deterministically Charged Quantum Dots in Photonic Crystal\n  Nanoresonators for Efficient Spin-Photon Interfaces: We demonstrate a novel method for deterministic charging of InAs quantum dots\nembedded in photonic crystal nanoresonators using a unique vertical p-n-i-n\njunction within the photonic crystal membrane. Charging is confirmed by the\nobservation of Zeeman splitting for magnetic fields applied in the Voigt\nconfiguration. Spectrally resolved photoluminescence measurements are\ncomplemented by polarization resolved studies that show the precise structure\nof the Zeeman quadruplet. Integration of quantum dots in nanoresonators\nstrongly enhances far-field collection efficiency and paves the way for the\nexploitation of enhanced spin-photon interactions for fabrication of efficient\nquantum nodes in a scalable solid state platform.",
        "positive": "Spin Injection in a Ballistic Two-Dimensional Electron Gas: We explore electrically injected, spin polarized transport in a ballistic\ntwo-dimensional electron gas. We augment the Buettiker-Landauer picture with a\nsimple, but realistic model for spin-selective contacts to describe multimode\nreservoir-to-reservoir transport of ballistic spin 1/2 particles. Clear and\nunambiguous signatures of spin transport are established in this regime, for\nthe simplest measurement configuration that demonstrates them directly. These\nnew effects originate from spin precession of ballistic carriers; they exhibit\nstrong dependence upon device geometry and vanish in the diffusive limit. Our\nresults have important implications for prospective ``spin transistor''\ndevices."
    },
    {
        "anchor": "Nuclear spin coherence in a quantum wire: We have observed millisecond-long coherent evolution of nuclear spins in a\nquantum wire at 1.2 K. Local, all-electrical manipulation of nuclear spins is\nachieved by dynamic nuclear polarization in the breakdown regime of the Integer\nQuantum Hall Effect combined with pulsed Nuclear Magnetic Resonance. The\nexcitation thresholds for the breakdown are significantly smaller than what\nwould be expected for our sample and the direction of the nuclear polarization\ncan be controlled by the voltage bias. As a four-level spin system, the device\nis equivalent to two qubits.",
        "positive": "Nonlinear electromagnetic response of a uniform electron gas: The linear electromagnetic response of a uniform electron gas to a\nlongitudinal electric field is determined, within the self-consistent-field\ntheory, by the linear polarizability and the Lindhard dielectric function.\nUsing the same approach we derive analytical expressions for the second- and\nthird-order nonlinear polarizabilities of the three-, two- and one-dimensional\nhomogeneous electron gases with the parabolic electron energy dispersion. The\nresults are valid both for degenerate (Fermi) and non-degenerate (Boltzmann)\nelectron gases. A resonant enhancement of the second and third harmonics\ngeneration due to a combination of the single-particle and collective (plasma)\nresonances is predicted."
    },
    {
        "anchor": "Phonon-Driven Electron Scattering and Magnetothermoelectric Effect in\n  Two-Dimensional Tin Selenide: The bulk tin selenide (SnSe) is the best thermoelectric material currently\nwith the highest figure-of-merit due to the strong phonon-phonon interactions.\nWe investigate the effect of electron-phonon coupling (EPC) on the transport\nproperties of two-dimensional (2D) SnSe sheet. We demonstrate that EPC plays a\nkey role in the scattering rate where the constant relaxation time\napproximation is deficient. The EPC strength is especially large in contrast to\nthat of pristine graphene. The scattering rate depends sensitively on the\nsystem temperatures and the carrier densities when the Fermi energy approaches\nthe band edge. We also investigate the magnetothermoelectric effect of the 2D\nSnSe. It is found that at low temperatures there are enormous magnetoelectrical\nresistivity and magnetothermal resistivity above 500\\%, suggesting the high\npotential for device applications. Our results agree reasonably well with the\nexperimental data.",
        "positive": "Dynamic nuclear polarisation in biased quantum wires with spin-orbit\n  interaction: We propose a new method for dynamic nuclear polarisation in a quasi\none-dimensional quantum wire utilising the spin-orbit interaction, the\nhyperfine interaction, and a finite source-drain potential difference. In\ncontrast with current methods, our scheme does not rely on external magnetic or\noptical sources which makes independent control of closely placed devices much\nmore feasible. Using this method, a significant polarisation of a few per cent\nis possible in currently available InAs wires which may be detected by\nconductance measurements. This may prove useful for nuclear-magnetic-resonance\nstudies in nanoscale systems as well as in spin-based devices where external\nmagnetic and optical sources will not be suitable."
    },
    {
        "anchor": "Polarization of ultrashort optical pulses in semiconductor superlattice\n  in a presence of magnetic field: The system of equations describing an ultrashort optical pulses propagation\nin semiconductor superlattice with applied magnetic field was obtained based on\nBoltzmann equation in the relaxation-time approximation for the single electron\ndistribution function and coupled Maxwell equations for the electromagnetic\nfield. It was demonstrated that an original linear-polarized optical pulse\ninitiates an orthogonal polarization in the field of a sample. The propagation\ndynamics of initiated and initial pulses in the sample was investigated. The\neffects of the lattice geometry have been elicited.",
        "positive": "Shot noise of spin current and spin transfer torque: We report the theoretical investigation of noise spectrum of spin current and\nspin transfer torque for non-colinear spin polarized transport in a spin-valve\ndevice which consists of normal scattering region connected by two\nferromagnetic electrodes. Our theory was developed using non-equilibrium\nGreen's function method and general non-linear $S^\\sigma-V$ and $S^\\tau-V$\nrelations were derived as a function of angle $\\theta$ between magnetization of\ntwo leads. We have applied our theory to a quantum dot system with a resonant\nlevel coupled with two ferromagnetic electrodes. It was found that for the MNM\nsystem, the auto-correlation of spin current is enough to characterize the\nfluctuation of spin current. For a system with three ferromagnetic layers,\nhowever, both auto-correlation and cross-correlation of spin current are needed\nto characterize the noise spectrum of spin current. Furthermore, the spin\ntransfer torque and the torque noise were studied for the MNM system. For a\nquantum dot with a resonant level, the derivative of spin torque with respect\nto bias voltage is proportional to $\\sin\\theta$ when the system is far away\nfrom the resonance. When the system is near the resonance, the spin transfer\ntorque becomes non-sinusoidal function of $\\theta$. The derivative of noise\nspectrum of spin transfer torque with respect to the bias voltage $N_\\tau$\nbehaves differently when the system is near or far away from the resonance.\nSpecifically, the differential shot noise of spin transfer torque $N_\\tau$ is a\nconcave function of $\\theta$ near the resonance while it becomes convex\nfunction of $\\theta$ far away from resonance. For certain bias voltages, the\nperiod $N_\\tau(\\theta)$ becomes $\\pi$ instead of $2\\pi$. For small $\\theta$, it\nwas found that the differential shot noise of spin transfer torque is very\nsensitive to the bias voltage and the other system parameters."
    },
    {
        "anchor": "Impurities as a source of flicker noise in graphene: We experimentally study the effect of different scattering potentials on the\nflicker noise observed in graphene devices on silica substrates. The noise in\nnominally identical devices is seen to behave in two distinct ways as a\nfunction of carrier concentration, changing either monotonically or\nnonmonotonically. We attribute this to the interplay between long- and\nshort-range scattering mechanisms. Water is found to significantly enhance the\nnoise magnitude and change the type of the noise behaviour. By using a simple\nmodel, we show that water is a source of long-range scattering.",
        "positive": "Quantum limited amplification from inelastic Cooper pair tunneling: Nature sets fundamental limits regarding how accurate the amplification of\nanalog signals may be. For instance, a linear amplifier unavoidably adds some\nnoise which amounts to half a photon at best. While for most applications much\nhigher noise levels are acceptable, the readout of microwave quantum systems,\nsuch as spin or superconducting qubits, requires noise as close as possible to\nthis ultimate limit. To date, it is approached only by parametric amplifiers\nexploiting non-linearities in superconducting circuits and driven by a strong\nmicrowave pump tone. However, this microwave drive makes them much more\ndifficult to implement and operate than conventional DC powered amplifiers,\nwhich so far suffer from much higher noise. Here we present the first\nexperimental proof that a simple DC-powered setup allows for amplification\nclose to the quantum limit. Our amplification scheme is based on the stimulated\nmicrowave photon emission accompanying inelastic Cooper pair tunneling through\na DC-biased Josephson junction, with the key to low noise lying in a well\ndefined auxiliary idler mode, in analogy to parametric amplifiers."
    },
    {
        "anchor": "Violation of the Wiedemann-Franz law in clean graphene layers: The Wiedemann-Franz law, connecting the electronic thermal conductivity to\nthe electrical conductivity of a disordered metal, is generally found to be\nwell satisfied even when electron-electron (e-e) interactions are strong. In\nultra-clean conductors, however, large deviations from the standard form of the\nlaw are expected, due to the fact that e-e interactions affect the two\nconductivities in radically different ways. Thus, the standard Wiedemann-Franz\nratio between the thermal and the electric conductivity is reduced by a factor\n$1+\\tau/\\tau_{\\rm th}^{\\rm ee}$, where $1/\\tau$ is the momentum relaxation\nrate, and $1/\\tau_{\\rm th}^{\\rm ee}$ is the relaxation time of the thermal\ncurrent due to e-e collisions. Here we study the density and temperature\ndependence of $1/\\tau_{\\rm th}^{\\rm ee}$ in the important case of doped, clean\nsingle layers of graphene, which exhibit record-high thermal conductivities. We\nshow that at low temperature $1/\\tau_{\\rm th}^{\\rm ee}$ is $8/5$ of the\nquasiparticle decay rate. We also show that the many-body renormalization of\nthe thermal Drude weight coincides with that of the Fermi velocity.",
        "positive": "Resonant optical spin initialization and readout of single silicon\n  vacancies in 4H-SiC: The silicon monovacancy in 4H-SiC is a promising candidate for solid-state\nquantum information processing. We perform high-resolution optical spectroscopy\non single V2 defects at cryogenic temperatures. We find favorable low\ntemperature optical properties that are essential for optical readout and\ncoherent control of its spin and for the development of a spin-photon\ninterface. The common features among individual defects include two narrow,\nnearly lifetime-limited optical transitions that correspond to $m_s{=}\\pm 3/2$\nand $m_s{=}\\pm 1/2$ spin states with no discernable zero-field splitting\nfluctuations. Initialization and readout of the spin states is characterized by\ntime-resolved optical spectroscopy under resonant excitation of these\ntransitions, showing significant differences between the $\\pm 3/2$ and $\\pm\n1/2$ spin states. These results are well-described by a theoretical model that\nstrengthens our understanding of the quantum properties of this defect."
    },
    {
        "anchor": "Non-equilibrium effects in the magnetic behavior of Co_3O_4\n  nanoparticles: We report detailed studies on non-equilibrium magnetic behavior of\nantiferromagnetic Co_3O_4 nanoparticles. Temperature and field dependence of\nmagnetization, wait time dependence of magnetic relaxation (aging), memory\neffects and temperature dependence of specific heat have been investigated to\nunderstand the magnetic behavior of these particles. We find that the system\nshows some features characteristic of nanoparticle magnetism such as\nbifurcation of field cooled (FC) and zero field cooled (ZFC) susceptibilities\nand a slow relaxation of magnetization. However, strangely, the temperature at\nwhich the ZFC magnetization peaks coincides with the bifurcation temperature\nand does not shift on application of magnetic fields up to 1 kOe, unlike most\nother nanoparticle systems. Aging effects in these particles are negligible in\nboth FC and ZFC protocol and memory effects are present only in FC protocol. We\nestimate the N\\'eel temperature by using Fisher's relation as well as directly\nby measurement of specific heat, thus testing the validity of Fisher's relation\nfor nanoparticles. We show that Co3O4 nanoparticles constitute a unique\naniferromagnetic system which develops a magnetic moment in the paramagnetic\nstate because of antiferromagnetic correlations and enters into a blocked state\nabove the N\\'eel temperature.",
        "positive": "Reversal of thermoelectric current in tubular nanowires: We calculate the charge current generated by a temperature bias between the\ntwo ends of a tubular nanowire. We show that in the presence of a transversal\nmagnetic field the current can change sign, i.e., electrons can either flow\nfrom the hot to the cold reservoir, or in the opposite direction, when the\ntemperature bias increases. This behavior occurs when the magnetic field is\nsufficiently strong, such that Landau and snaking states are created, and the\nenergy dispersion is non-monotonic with respect to the longitudinal wave\nvector. The sign reversal can survive in the presence of impurities. We predict\nthis result for core/shell nanowires, for uniform nanowires with surface states\ndue to the Fermi level pinning, and for topological insulator nanowires."
    },
    {
        "anchor": "Defect healing and charge transfer mediated valley polarization in\n  MoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures: Monolayer transition metal dichalcogenides (TMDC) grown by chemical vapor\ndeposition (CVD) are plagued by a significantly lower optical quality compared\nto exfoliated TMDC. In this work we show that the optical quality of CVD-grown\nMoSe$_2$ is completely recovered if the material is sandwiched in\nMoS$_2$/MoSe$_2$/MoS$_2$ trilayer van der Waals heterostructures. We show by\nmeans of density-functional theory that this remarkable and unexpected result\nis due to defect healing: S atoms of the more reactive MoS$_2$ layers are\ndonated to heal Se vacancy defects in the middle MoSe$_2$ layer. In addition,\nthe trilayer structure exhibits a considerable charge-transfer mediated valley\npolarization of MoSe$_2$ without the need for resonant excitation. Our\nfabrication approach, relying solely on simple flake transfer technique, paves\nthe way for the scalable production of large-area TMDC materials with excellent\noptical quality.",
        "positive": "Born-Oppenheimer Breakdown in Graphene: The Born-Oppenheimer approximation (BO) has proven effective for the accurate\ndetermination of chemical reactions, molecular dynamics and phonon frequencies\nin a wide range of metallic systems. Graphene, recently discovered in the free\nstate, is a zero band-gap semiconductor, which becomes a metal if the Fermi\nenergy is tuned applying a gate-voltage Vg. Graphene electrons near the Fermi\nenergy have twodimensional massless dispersions, described by Dirac cones. Here\nwe show that a change in Vg induces a stiffening of the Raman G peak (i.e. the\nzone-center E2g optical phonon), which cannot be described within BO. Indeed,\nthe E2g vibrations cause rigid oscillations of the Dirac-cones in the\nreciprocal space. If the electrons followed adiabatically the Dirac-cone\noscillations, no change in the phonon frequency would be observed. Instead,\nsince the electron-momentum relaxation near the Fermi level is much slower than\nthe phonon motion, the electrons do not follow the Dirac-cone displacements.\nThis invalidates BO and results in the observed phonon stiffening. This\nspectacular failure of BO is quite significant since BO has been the\nfundamental paradigm to determine crystal vibrations from the early days of\nquantum mechanics."
    },
    {
        "anchor": "Probing the nodal structure of Landau level wave functions in real space: The inversion layer of p-InSb(110) obtained by Cs adsorption of 1.8 % of a\nmonolayer is used to probe the Landau level wave functions within smooth\npotential valleys by scanning tunnelling spectroscopy at 14 T. The nodal\nstructure becomes apparent as a double peak structure of each spin polarized\nfirst Landau level, while the zeroth Landau level exhibits a single peak per\nspin level only. The real space data show single rings of the valley-confined\ndrift states for the zeroth Landau level and double rings for the first Landau\nlevel. The result is reproduced by a recursive Green's function algorithm using\nthe potential landscape obtained experimentally. We show that the result is\ngeneric by comparing the local density of states from the Green's function\nalgorithm with results from a well controlled analytic model based on the\nguiding center approach.",
        "positive": "Non-diffusive Lattice Thermal Transport in Si-Ge Alloy Nanowires: We present a calculation of the lattice thermal conductivity of Si-Ge\nnanowires (NWs), based on solving the Boltzmann transport equation by the Monte\nCarlo method of sampling the phonon mean free paths. We augment the previous\nwork with the full phonon dispersion and a partially diffuse momentum-dependent\nspecularity model for boundary roughness scattering. We find that phonon\nflights are comprised of a mix of long free-flights over several {\\mu}m\ninterrupted by bursts of short flights, resulting in a heavy tailed\ndistribution of flight lengths, typically encountered in L\\'{e}vy walk\ndynamics. Consequently, phonon transport in Si-Ge NWs is neither entirely\nballistic nor diffusive; instead, it falls into an intermediate regime called\nsuperdiffusion where thermal conductivity scales with the length of the NW as\n$\\kappa \\propto L^{\\alpha}$ with the exponent of length dependence\n$\\alpha\\approx 0.33$ over a broad range of wire lengths 10 nm$<L<$10 $\\mu$m\nregardless of diameter and roughness. We conclude that thermal conductivity in\nSi-Ge alloy NWs is length-dependent up to 10 $\\mu$m and therefore can be tuned\nfor thermoelectric applications."
    },
    {
        "anchor": "Connectivity of edge and surface states in topological insulators: The edge states of a two-dimensional quantum spin Hall (QSH) insulator form a\none-dimensional helical metal which is responsible for the transport property\nof the QSH insulator. Conceptually, such a one-dimensional helical metal can be\nattached to any scattering region as the usual metallic leads. We study the\nanalytical property of the scattering matrix for such a conceptual\nmultiterminal scattering problem in the presence of time reversal invariance.\nAs a result, several theorems on the connectivity property of helical edge\nstates in two-dimensional QSH systems as well as surface states of\nthree-dimensional topological insulators are obtained. Without addressing real\nmodel details, these theorems, which are phenomenologically obtained, emphasize\nthe general connectivity property of topological edge/surface states from the\nmere time reversal symmetry restriction.",
        "positive": "Anisotropic Pauli spin-blockade effect and spin-orbit interaction field\n  in an InAs nanowire double quantum dot: We report on experimental detection of the spin-orbit interaction field in an\nInAs nanowire double quantum dot device. In the spin blockade regime, leakage\ncurrent through the double quantum dot is measured and is used to extract the\neffects of spin-orbit interaction and hyperfine interaction on spin state\nmixing. At finite magnetic fields, the leakage current arising from the\nhyperfine interaction is suppressed and the spin-orbit interaction dominates\nspin state mixing. We observe dependence of the leakage current on the applied\nmagnetic field direction and determine the direction of the spin-orbit\ninteraction field. We show that the spin-orbit field lies in a direction\nperpendicular to the nanowire axis but with a pronounced off-substrate-plane\nangle. It is for the first time that such an off-substrate-plane spin-orbit\nfield in an InAs nanowire has been detected. The results are expected to have\nan important implication in employing InAs nanowires to construct spin-orbit\nqubits and topological quantum devices."
    },
    {
        "anchor": "Hole spin resonance and spin-orbit coupling in a silicon\n  metal-oxide-semiconductor field-effect transistor: We study hole spin resonance in a p-channel silicon metal-oxide-semiconductor\nfield-effect transistor. In the sub-threshold region, the measured source-drain\ncurrent reveals a double dot in the channel. The observed spin resonance\nspectra agree with a model of strongly coupled two-spin states in the presence\nof a spin-orbit-induced anti-crossing. Detailed spectroscopy at the\nanti-crossing shows a suppressed spin resonance signal due to\nspin-orbit-induced quantum state mixing. This suppression is also observed for\nmulti-photon spin resonances. Our experimental observations agree with\ntheoretical calculations.",
        "positive": "Bulk contributions to the Casimir interaction of Dirac materials: Exploiting methods of Quantum Field Theory we compute the bulk polarization\ntensor and bulk dielectric functions for Dirac materials in the presence of a\nmass gap, chemical potential, and finite temperature. Using these results (and\nneglecting eventual boundary effects), we study the Casimir interaction of\nDirac materials. We describe in detail the characteristic features of the\ndielectric functions and their influence on the Casimir pressure."
    },
    {
        "anchor": "Aharonov-Bohm effect in one-channel weakly disordered rings: A new diagrammatic method, which is a reformulation of Berezinskii's\ntechnique, is constructed to study the density of electronic states\n$\\rho(\\epsilon,\\phi)$ of a one-channel weakly disordered ring, threaded by an\nexternal magnetic flux. The exact result obtained for the density of states\nshows an oscillation of $\\rho(\\epsilon,\\phi)$ with a period of the flux quantum\n$\\phi_0= hc/e $. As the sample length (or the impurity concentration) is\nreduced, a transition takes place from the weak localization regime (L >> l) to\nthe ballistic one (L <= l). The analytical expression for the density of states\nshows the exact dependence of $\\rho(\\epsilon,\\phi)$ on the ring's circumference\nand on disorder strength for both regimes.",
        "positive": "Magneto-optical spectroscopy of single charge-tunable InAs/GaAs quantum\n  dots emitting at telecom wavelengths: We report on the optical properties of single InAs/GaAs quantum dots emitting\nnear the telecommunication O-band, probed via Coulomb blockade and non-resonant\nphotoluminescence spectroscopy, in the presence of external electric and\nmagnetic fields. We extract the physical properties of the electron and hole\nwavefunctions, including the confinement energies, interaction energies,\nwavefunction lengths, and $g$-factors. For excitons, we measure the permanent\ndipole moment, polarizability, diamagnetic coefficient, and Zeeman splitting.\nThe carriers are determined to be in the strong confinement regime. Large range\nelectric field tunability, up to 7 meV, is demonstrated for excitons. We\nobserve a large reduction, up to one order of magnitude, in the diamagnetic\ncoefficient when rotating the magnetic field from Faraday to Voigt geometry due\nto the unique dot morphology. The complete spectroscopic characterization of\nthe fundamental properties of long-wavelength dot-in-a-well structures provides\ninsight for the applicability of quantum technologies based on quantum dots\nemitting at telecom wavelengths."
    },
    {
        "anchor": "A Droplet State in an Interacting Two-Dimensional Electron System: It is well known that the dielectric constant of two-dimensional (2D)\nelectron system goes negative at low electron densities. A consequence of the\nnegative dielectric constant could be the formation of the droplet state. The\ndroplet state is a two-phase coexistence region of high density liquid and low\ndensity \"gas\". In this paper, we carry out energetic calculations to study the\nstability of the droplet ground state. The possible relevance of the droplet\nstate to recently observed 2D metal-insulator transition is also discussed.",
        "positive": "Observation of superconductivity in silicene: A possible superconducting gap, about 35 meV, was observed in silicene on\nAg(111) substrate by scanning tunneling spectroscopy. The\ntemperature-dependence measurement reveals a superconductor-metal transition\nand gives a critical temperature of about 35-40K. The possible mechanism of\nsuperconductivity in silicene is discussed."
    },
    {
        "anchor": "Magnetodielectric effect in nickel nanosheet-Na-4 mica composites: Nickel nanosheets of thickness 0.6 nm were grown within the nanochannels of\nNa-4 mica template. The specimens show magnetodielectric effect at room\ntemperature with a change of dielectric constant as a function of magnetic\nfield, the electric field frequency varying from 100 to 700 kHz. A decrease of\n5% in the value of dielectric constant was observed up to a field of 1.2 Tesla.\nThis is explained by an inhomogeneous two-component composite model as\ntheoretically proposed recently. The present approach will open up synthesis of\nvarious nanocomposites for sensor applications.",
        "positive": "Weak localization of Dirac fermions in graphene beyond the diffusion\n  regime: We develop a microscopic theory of the weak localization of two-dimensional\nmassless Dirac fermions which is valid in the whole range of classically weak\nmagnetic fields. The theory is applied to calculate magnetoresistance caused by\nthe weak localization in graphene and conducting surfaces of bulk topological\ninsulators."
    },
    {
        "anchor": "Schr\u00f6dinger cats in quantum-dot--cavity systems: A Schr\\\"odinger-cat state is a coherent superposition of macroscopically\ndistinguishable quantum states, in quantum optics usually realized as\nsuperposition of coherent states. Protocols to prepare photonic cats have been\npresented for atomic systems. Here, we investigate in what manner and how well\nthe preparation protocols can be transferred to a solid state platform, namely\na semiconductor quantum-dot--cavity system. In quantum-dot--cavity systems\nthere are many disruptive influences like cavity losses, the radiative decay of\nthe quantum dot, and the pure-dephasing type coupling to longitudinal acoustic\nphonons. We show that for one of the protocols these influences kill the\nquantum coherence between the states forming the cat, while for a second\nprotocol a parameter regime can be identified where the essential\ncharacteristics of Schr\\\"odinger-cat states survive the environmental\ninfluences under realistic conditions.",
        "positive": "Oscillatory exchange bias and training effects in nanocrystalline\n  Pr0.5Ca0.5MnO3: We report on exchange bias effects in 10 nm particles of Pr0.5Ca0.5MnO3 which\nappear as a result of competing interactions between the ferromagnetic\n(FM)/anti-ferromagnetic (AFM) phases. The fascinating new observation is the\ndemonstration of the temperature dependence of oscillatory exchange bias (OEB)\nand is tunable as a function of cooling field strength below the SG phase, may\nbe attributable to the presence of charge/spin density wave (CDW/SDW) in the\nAFM core of PCMO10. The pronounced training effect is noticed at 5 K from the\nvariation of the EB field as a function of number of field cycles (n) upon the\nfield cooling (FC) process. For n > 1, power-law behavior describes the\nexperimental data well; however, the breakdown of spin configuration model is\nnoticed at n \\geq 1."
    },
    {
        "anchor": "Electrical control of the sign of the g-factor in a GaAs hole quantum\n  point contact: Zeeman splitting of 1D hole subbands is investigated in quantum point\ncontacts (QPCs) fabricated on a (311) oriented GaAs-AlGaAs heterostructure.\nTransport measurements can determine the magnitude of the g-factor, but cannot\nusually determine the sign. Here we use a combination of tilted fields and a\nunique off-diagonal element in the hole g-tensor to directly detect the sign of\ng*. We are able to tune not only the magnitude, but also the sign of the\ng-factor by electrical means, which is of interest for spintronics\napplications. Furthermore, we show theoretically that the resulting behavior of\ng* can be explained by the momentum dependence of the spin-orbit interaction.",
        "positive": "Theory of unconventional quantum Hall effect in strained graphene: We show through both theoretical arguments and numerical calculations that\ngraphene discerns an unconventional sequence of quantized Hall conductivity,\nwhen subject to both magnetic fields (B) and strain. The latter produces\ntime-reversal symmetric pseudo/axial magnetic fields (b). The single-electron\nspectrum is composed of two interpenetrating sets of Landau levels (LLs),\nlocated at $\\pm \\sqrt{2 n |b \\pm B|}$, $n=0, 1, 2, \\cdots$. For $b>B$, these\ntwo sets of LLs have opposite \\emph{chiralities}, resulting in {\\em\noscillating} Hall conductivity between 0 and $\\mp 2 e^2/h$ in electron and hole\ndoped system, respectively, as the chemical potential is tuned in the vicinity\nof the neutrality point. The electron-electron interactions stabilize various\ncorrelated ground states, e.g., spin-polarized, quantum spin-Hall insulators at\nand near the neutrality point, and possibly the anomalous Hall insulating phase\nat incommensurate filling $\\sim B$. Such broken-symmetry ground states have\nsimilarities as well as significant differences from their counterparts in the\nabsence of strain. For realistic strength of magnetic fields and interactions,\nwe present scaling of the interaction-induced gap for various Hall states\nwithin the zeroth Landau level."
    },
    {
        "anchor": "Transient Nature of Negative Capacitance in Ferroelectric Field-Effect\n  Transistors: Negative capacitance (NC) in ferroelectrics, which stems from the imperfect\nscreening of polarization, is considered a viable approach to lower voltage\noperation in the field-effect transistors (FETs) used in logic switches. In\nthis paper, we discuss the implications of the transient nature of negative\ncapacitance for its practical application. It is suggested that the NC effect\nneeds to be characterized at the proper time scale to identify the type of\ncircuits where functional NC-FETs can be used effectively.",
        "positive": "Current-Controlled Skyrmionic Diode: In order to address many of the challenges and bottlenecks currently\nexperienced by traditional charge based technologies, various alternatives are\nbeing actively explored to provide potential solutions of device\nminiaturization and scaling in the more-than-MOORE era. Amongst these\nalternatives, spintronics physics and devices have recently attracted a rapidly\nincreasing interest by exploiting the additional degree of electron's spins.\nFor example, magnetic domain-wall racetrack-memory and logic devices have been\nrealized via manipulating domain-wall motion. As compared to domain-wall based\ndevices, magnetic skyrmions have the advantages of ultra-small size (typically\n5-100 nm in diameter), facile current-driven motion, topological stability and\npeculiar emergent electrodynamics, promising for next-generation electronics\napplications in the more-than-Moore regime. In this work, a magnetic meron\ndiode, which behaves like a PN-junction diode, is demonstrated for the first\ntime, by tailoring the current-controlled unidirectional motion of edge-merons\n(i.e., fractional skyrmions) in a nanotrack with interfacial\nDzyaloshinskii-Moriya interaction. The working principles of the meron diode,\ntheoretically expected from the Thiele equation for topological magnetic\nobjects, are further verified by micromagnetic simulations. The present study\nreveals topology-independent transport property of magnetic objects, and is\nexpected to open the vista toward integrated composite circuitry, with unified\ndata storage and processing, based on a single magnetic chip, as the meron\ndiode can be used either, as a building block, to develop complex logic\ncomponents or, as a signal controller, to interconnect skyrmion, domain-wall,\nand even spin-wave devices."
    },
    {
        "anchor": "Sub-diffusive phases in open clean long-range systems: We show that a one-dimensional ordered fermionic lattice system with\npower-law-decaying hopping, when connected to two baths at its two ends with\ndifferent chemical potentials at zero temperature, features two phases showing\nsub-diffusive scaling of conductance with system size. These phases have no\nanalogues in the isolated system (i.e, in absence of the baths) where the\ntransport is perfectly ballistic. In the open system scenario, interestingly,\nthere occurs two chemical-potential-driven sub-diffusive to ballistic phase\ntransitions at zero temperature. We discuss how these phase transitions, to our\nknowledge, are different from all the known non-equilibrium quantum phase\ntransitions. We provide a clear understanding of the microscopic origin of\nthese phases and argue that the sub-diffusive phases are robust against the\npresence of arbitrary number-conserving many-body interactions in the system.\nThese phases showing sub-diffusive scaling of conductance with system size in a\ntwo-terminal set-up are therefore universal properties of all ordered\none-dimensional number-conserving fermionic systems with power-law-decaying\nhopping at zero temperature.",
        "positive": "Thermal conduction across a boron nitride and silicon oxide interface: The needs for efficient heat removal and superior thermal conduction in\nnano/micro devices have triggered tremendous studies in low-dimensional\nmaterials with high thermal conductivity. Hexagonal boron nitride (h-BN) is\nbelieved to be one of the candidates for thermal management and heat\ndissipation due to its novel physical properties, i.e. thermal conductor and\nelectrical insulator. Here we reported interfacial thermal resistance between\nfew-layer h-BN and its silicon oxide substrate using differential 3 omega\nmethod. The measured interfacial thermal resistance is around ~1.6*10-8 m2K/W\nfor monolayer h-BN and ~3.4*10-8 m2K/W for 12.8nm-thick h-BN in metal/h-BN/SiO2\ninterfaces. Our results suggest that the voids and gaps between substrate and\nthick h-BN flakes limit the interfacial thermal conduction. This work provides\na deeper understanding of utilizing h-BN flake as lateral heat spreader in\nelectronic and optoelectronic nano/micro devices with further miniaturization\nand integration."
    },
    {
        "anchor": "Molecular Nanoelectronics: Molecular electronics is envisioned as a promising candidate for the\nnanoelectronics of the future. More than a possible answer to ultimate\nminiaturization problem in nanoelectronics, molecular electronics is foreseen\nas a possible way to assemble a large numbers of nanoscale objects (molecules,\nnanoparticules, nanotubes and nanowires) to form new devices and circuit\narchitectures. It is also an interesting approach to significantly reduce the\nfabrication costs, as well as the energetical costs of computation, compared to\nusual semiconductor technologies. Moreover, molecular electronics is a field\nwith a large spectrum of investigations: from quantum objects for testing new\nparadigms, to hybrid molecular-silicon CMOS devices. However, problems remain\nto be solved (e.g. a better control of the molecule-electrode interfaces,\nimprovements of the reproducibility and reliability, etc...).",
        "positive": "The two-bands model of the magnetic tunnel junctions in the Fe/Cr/MgO/Fe\n  structure: In this paper we present theoretical studies of spin dependent transport in\nFe/Cr/MgO/Fe tunnel junctions with non-collinear alignment of magnetizations of\nmetallic layers comprising these MTJs. Calculations are performed with use of\nnon-equilibrium Green function technique in the framework of Keldysh formalism.\nWKB approximation is used for wave and Green functions in the trapezoidal\nbarrier region under applied voltage. Electronic structure of ferromagnetic\nelectrodes is modeled with two bands model, i.e. with majority s-electrons and\nminority d-holes. Furthermore, we introduce s-d hybridization by calculating\nthe corresponding perturbation corrections for the wave and Green functions."
    },
    {
        "anchor": "Low temperature high-frequency monolayer graphene conductivity as a\n  manifestation of Zitterbewegung: We consider the Zitterbewegung of Dirac electrons in the monolayer graphene\nas the nonrelativistic analog of the phenomenon predicted by E. Schr\\\"odinger\nfor the relativistic electrons in the free space. So we show that the Dirac\nelectrons of monolayer graphene oscillate, i.e. produce fast fluctuation of an\nelectron position around the mean value with rather high frequency but much\nless than the relativistic electrons in the free space. We also study relation\nbetween the Zitterbewegung of the conductivity electrons wave packet formed by\nthe Fermi-Dirac distribution and the high-frequency complex conductivity of the\nmonolayer graphene. Thus we find that the electromagnetic resonance properties\nof the monolayer graphene can be simulated by the set of the equivalent\noscillatory circuits. This is useful in order to impart illustrativeness to\nelectromagnetic processes that is particularly important for incorporation of\ngraphene into electronic systems.",
        "positive": "Electronic transport through ballistic chaotic cavities: reflection\n  symmetry, direct processes, and symmetry breaking: We extend previous studies on transport through ballistic chaotic cavities\nwith spatial left-right (LR) reflection symmetry to include the presence of\ndirect processes. We first analyze fully LR-symmetric systems in the presence\nof direct processes and compare the distribution w(T) of the transmission\ncoefficient T with that for an asymmetric cavity with the same \"optical\" S\nmatrix. We then study the problem of \"external mixing\" of the symmetry caused\nby an asymmetric coupling of the cavity to the outside. We first consider the\ncase where symmetry breaking arises because two symmetrically positioned\nwaveguides are coupled to the cavity by means of asymmetric tunnel barriers.\nAlthough this system is asymmetric with respect to the LR operation, it has a\nstriking memory of the symmetry of the cavity it was constructed from.\nSecondly, we break LR symmetry in the absence of direct proceses by\nasymmetrically positioning the two waveguides and compare the results with\nthose for the completely asymmetric case."
    },
    {
        "anchor": "Large effective mass and interaction-enhanced Zeeman splitting of\n  $K$-valley electrons in MoSe$_2$: We study the magnetotransport of high-mobility electrons in monolayer and\nbilayer MoSe$_2$, which show Shubnikov-de Haas (SdH) oscillations and quantum\nHall states in high magnetic fields. An electron effective mass of 0.8$m_e$ is\nextracted from the SdH oscillations' temperature dependence; $m_e$ is the bare\nelectron mass. At a fixed electron density the longitudinal resistance shows\nminima at filling factors (FFs) that are either predominantly odd, or\npredominantly even, with a parity that changes as the density is tuned. The SdH\noscillations are insensitive to an in-plane magnetic field, consistent with an\nout-of-plane spin orientation of electrons at the $K$-point. We attribute the\nFFs parity transitions to an interaction enhancement of the Zeeman energy as\nthe density is reduced, resulting in an increased Zeeman-to-cyclotron energy\nratio.",
        "positive": "Coulomb interaction and transient charging of excited states in open\n  nanosystems: We obtain and analyze the effect of electron-electron Coulomb interaction on\nthe time dependent current flowing through a mesoscopic system connected to\nbiased semi-infinite leads. We assume the contact is gradually switched on in\ntime and we calculate the time dependent reduced density operator of the sample\nusing the generalized master equation. The many-electron states (MES) of the\nisolated sample are derived with the exact diagonalization method. The chemical\npotentials of the two leads create a bias window which determines which MES are\nrelevant to the charging and discharging of the sample and to the currents,\nduring the transient or steady states. We discuss the contribution of the MES\nwith fixed number of electrons N and we find that in the transient regime there\nare excited states more active than the ground state even for N=1. This is a\ndynamical signature of the Coulomb blockade phenomenon. We discuss numerical\nresults for three sample models: short 1D chain, 2D lattice, and 2D parabolic\nquantum wire."
    },
    {
        "anchor": "Geometric, electronic properties and the thermodynamics of pure and\n  Al--doped Li clusters: The first--principles density functional molecular dynamics simulations have\nbeen carried out to investigate the geometric, the electronic, and the finite\ntemperature properties of pure Li clusters (Li$_{10}$, Li$_{12}$) and Al--doped\nLi clusters (Li$_{10}$Al, Li$_{10}$Al$_2$). We find that addition of two Al\nimpurities in Li$_{10}$ results in a substantial structural change, while the\naddition of one Al impurity causes a rearrangement of atoms. Introduction of\nAl--impurities in Li$_{10}$ establishes a polar bond between Li and nearby Al\natom(s), leading to a multicentered bonding, which weakens the Li--Li metallic\nbonds in the system. These weakened Li--Li bonds lead to a premelting feature\nto occur at lower temperatures in Al--doped clusters. In Li$_{10}$Al$_2$, Al\natoms also form a weak covalent bond, resulting into their dimer like behavior.\nThis causes Al atoms not to `melt' till 800 K, in contrast to the Li atoms\nwhich show a complete diffusive behavior above 400 K. Thus, although one Al\nimpurity in Li$_{10}$ cluster does not change its melting characteristics\nsignificantly, two impurities results in `surface melting' of Li atoms whose\nmotions are confined around Al dimer.",
        "positive": "Pseudo-spin-dependent scattering in carbon nanotubes: The breaking of symmetry is the ground on which many physical phenomena are\nexplained. This is important in particular for bipartite lattice structure as\ngraphene and carbon nanotubes, where particle-hole and pseudo-spin are relevant\nsymmetries. Here we investigate the role played by the defect-induced breaking\nof these symmetries in the electronic scattering properties of armchair\nsingle-walled carbon nanotubes. From Fourier transform of the local density of\nstates we show that the active electron scattering channels depend on the\nconservation of the pseudo-spin. Further, we show that the lack of\nparticle-hole symmetry is responsible for the pseudo-spin selection rules\nobserved in several experiments. This symmetry breaking arises from the lattice\nreconstruction appearing at defect sites. Our analysis gives an intuitive way\nto understand the scattering properties of carbon nanotubes, and can be\nemployed for newly interpret several experiments on this subject. Further, it\ncan be used to design devices such as pseudo-spin filter by opportune defect\nengineering."
    },
    {
        "anchor": "Quantum spin Hall effect induced by non-magnetic and magnetic staggered\n  potentials: We have a comparative study of the quantum spin Hall (QSH) effects induced by\nnon-magnetic and magnetic staggered potentials respectively and show that they\nhave the same effect in driving the topological phase transition. The result\nimplies that both time-reversal (${\\cal T}$) preserving and breaking systems\ncan host QSH effect. We also investigate the stability of the resulting QSH\neffect to disorder and find that for ${\\cal T}$ invariant system the edge\nstates are always robust while those of ${\\cal T}$ breaking system are also\nrobust if there is additional symmetry in the system.",
        "positive": "Non-linear Magnetoresistance Oscillations in Intensely Irradiated\n  Two-Dimensional Electron Systems Induced by Multi-Photon Processes: We report on magneto-oscillations in differential resistivity of a\ntwo-dimensional electron system subject to intense microwave radiation. The\nperiod of these oscillations is determined not only by microwave frequency but\nalso by its intensity. A theoretical model based on quantum kinetics at high\nmicrowave power captures all important characteristics of this phenomenon which\nis strongly nonlinear in microwave intensity. Our results demonstrate a crucial\nrole of the multi-photon processes near the cyclotron resonance and its\nharmonics in the presence of strong dc electric field and offer a unique way to\nreliably determine the intensity of microwaves acting on electrons."
    },
    {
        "anchor": "Quantum Anomaly and Effective Field Description of a Quantum Chaotic\n  Billiard: We investigate the effective field theory of a quantum chaotic billiard from\na new perspective of quantum anomalies, which result from the absence of\ncontinuous spectral symmetry in quantized systems. It is shown that commutators\nof composite operators on the energy shell acquire anomalous part. The presence\nof the anomaly allows one to introduce effective dual fields as phase variables\nwithout any additional coarse-graining nor ensemble averaging in a ballistic\nsystem. The spectral Husimi function plays a role as the corresponding\namplitude.",
        "positive": "Observation of Photoluminescence from a Natural van der Waals\n  Heterostructure: Van der Waals heterostructures comprised of two-dimensional (2D) materials\noffer a platform to obtain materials by design with unique electronic\nproperties. Franckeite (Fr) is a naturally occurring van der Waals\nheterostructure comprised of two distinct alternately stacked semiconducting\nlayers; (i) SnS$_2$ layer and (ii) Pb$_3$SbS$_4$. Though both layers in the\nheterostructure are semiconductors, the photoluminescence from Franckeite\nremains elusive. Here, we report the observation of photoluminescence (PL) from\nFranckeite for the first time. We observed two PL peaks at ~ 1.93 eV and ~ 2.11\neV. By varying the temperature from 1.5 K to 80 K, we found that the PL peak\nposition redshifts and the integrated intensity decreases slowly as we increase\nthe temperature. We observed linear dependence of photoluminescence integrated\nintensity on excitation laser power indicating that the photoluminescence is\noriginating from free excitons in the SnS$_2$ layer of Fr. By comparing the PL\nfrom Fr with the PL from a monolayer MoS$_2$, we determined that the PL quantum\nefficiency from Fr is an order of magnitude lower than that of a monolayer\nMoS$_2$. Our study provides a fundamental understanding of the optical behavior\nin a complex naturally occurring van der Waals heterostructure, and may pave an\navenue toward developing nanoscale optical and optoelectronic devices with\ntailored properties."
    },
    {
        "anchor": "Time resolved transport properties of a $Y$-junction of\n  Tomonaga-Luttinger liquids: We study time resolved transport properties of a $Y$-junction composed of\ninteracting one-dimensional quantum wires using a bosonization approach. In\nparticular, we investigate the AC conductivity of the $Y$-junction formed from\nfinite length Tomonaga-Luttinger liquid wires based on a plasmon scattering\napproach for injected charge pulses of arbitrary shapes. In addition, we\ncalculate the tunneling current and quantum noise of the $Y$-junction arising\nfrom point-like tunneling impurities at the junction, including finite\ntemperature effects. Our results will be useful for designing nano-electronic\nquantum circuits, and for interpreting time-resolved experiments [H. Kamata et.\nal. in Nat. Nanotechnol. 9, 177 (2014)] in interacting wires and their\njunctions.",
        "positive": "Quantum thermodynamics with a Josephson-photonics setup: Josephson-photonics devices have emerged in the last years as versatile\nplatforms to study light-charge interactions far from equilibrium and to create\nnonclassical radiation. Their potential to operate as nanoscale heat engines\nhas also been discussed. The complementary mode of cooling is investigated here\nin the regimes of low and large photon occupancy, where nonlinearities are\nessential."
    },
    {
        "anchor": "Valley-dependent spin-orbit torques in two dimensional hexagonal\n  crystals: We study spin-orbit torques in two dimensional hexagonal crystals such as\ngraphene, silicene, germanene and stanene. The torque possesses two components,\na field-like term due to inverse spin galvanic effect and an antidamping torque\noriginating from Berry curvature in mixed spin-$k$ space. In the presence of\nstaggered potential and exchange field, the valley degeneracy can be lifted and\nwe obtain a valley-dependent Berry curvature, leading to a tunable antidamping\ntorque by controlling the valley degree of freedom. The valley imbalance can be\nas high as 100\\% by tuning the bias voltage or magnetization angle. These\nfindings open new venues for the development of current-driven spin-orbit\ntorques by structural design.",
        "positive": "Readout of a dopant spin in the anisotropic quantum dot with a single\n  magnetic ion: Owing to exchange interaction between the exciton and magnetic ion, a quantum\ndot embedding a single magnetic ion is a great platform for optical control of\nindividual spin. In particular, a quantum dot provides strong and sharp optical\ntransitions, which give experimental access to spin states of an individual\nmagnetic ion. We show, however, that physics of quantum dot excitons also\ncomplicate spin readout and optical spin manipulation in such a system. This is\ndue to electron-hole exchange interaction in anisotropic quantum dots, which\naffects the polarization of the emission lines. One of the consequences is that\nthe intensity of spectral lines in a single spectrum are not simply\nproportional to the population of various spin states of magnetic ion. In order\nto provide a solution of the above problem, we present a method of extracting\nboth the spin polarisation degree of a neutral exciton and magnetic dopant\ninside a semiconductor quantum dot in an external magnetic field. Our approach\nis experimentally verified on a system of CdSe/ZnSe quantum dot containing a\nsingle Fe$^{2+}$ ion. Both the resonant and non-resonant excitation regimes are\nexplored resulting in a record high optical orientation efficiency of dopant\nspin in the former case. The proposed solutions can be easily expanded to any\nother system of quantum dots containing magnetic dopants."
    },
    {
        "anchor": "Compensation of the Kondo effect in quantum dots coupled to\n  ferromagnetic leads within equation of motion approach: We propose a new approximation scheme within equation of motion approach\n(EOM) to spin polarized transport through a quantum dot coupled to\nferromagnetic leads. It has some advantages over a widely used in the\nliterature standard EOM technique, in particular when we are interested in spin\npolarized quantities. Namely, it gives the values of the dot spin polarization\nwhich are closer to the ones obtained within numerical renormalization group\n(NRG), than the standard EOM approach. While restoring the Kondo effect, the\nspin polarization vanishes and the transport becomes unpolarized, in agreement\nwith NRG and a real time diagrammatic calculations. The standard EOM procedure\ngives nonzero values of the spin polarization, and the transport is still spin\npolarized. Both approximations give the same correct splitting of the Kondo\npeaks due to ferromagnetism in the electrodes.",
        "positive": "Characterization of Single-Walled Carbon Nanotubes with Nodal Structural\n  Defects: Recently experiments showed that nodal structural defects are readily formed\nin the synthesis of single-walled carbon nanotubes (SWNTs) and consequently,\nSWNTs are likely to deviate from well-defined seamless tubular structures.\nHere, using graphene-helix growth model, we describe structural details of\nfeasible nodal defects in SWNTs and investigate how mechanical and electronic\nproperties of SWNTs would change in the presence of them using computational\nmethods. Surprisingly atomistic simulations of SWNTs with nodal defects show\nexcellent agreement with previous structural, tensile, and ball-milling\nexperiments whose results cannot be explained using conventional models. The\ntensile failure of SWNTs with nodal defects requires about four- or six-fold\nlower strength than pristine ones and these SWNTs are comparatively prone to\ndamage under a lateral compressive biting. We reveal that electronic band-gap\nof SWNT(12,8) would be remarkably reduced in the presence of nodal defects.\nThis study strongly indicates universality of nodal defects in SWNTs requesting\nnew theoretical framework in SWNT modelling for proper characteristics\nprediction."
    },
    {
        "anchor": "Model of coherent optical spin manipulation through hot trion states in\n  p-doped InAs/GaAs quantum dots: A new generalised group-theoretical approach, based on master\nMaxwell-pseudospin equations, is proposed to explain recently observed enhanced\ncircular dichroism in the excited state emission from p-doped quantum dot\nensembles under resonant circularly polarised excitation into hot trion states,\nherein referred to as \"spin-filtering effect\". The theory agrees remarkably\nwell with polarised time-resolved photoluminescence experiments, yielding\nlargely unknown inter- and intra-shell spin relaxation time scales. This\napproach allows to predict optimum pulse parameters for control of spin\ndynamics, which will enable exploitation of the effect in all-optical\nspin-based quantum technologies.",
        "positive": "Hyperfine-Enhanced Gyromagnetic Ratio of a Nuclear Spin in Diamond: Nuclear spins in the solid state environment of diamond are highly coherent,\nbut difficult to rapidly control due to the small nuclear gyromagnetic ratio.\nHere we demonstrate a more than 50-fold enhancement of the effective nuclear\ngyromagnetic ratio by coupling the nuclear spin to an electronic spin of a\nnitrogen-vacancy (NV) center in diamond. The enhancement allows for faster\nnuclear spin rotations and is in good agreement with second-order perturbation\ntheory. The method may be applied to other systems with similar\nelectron-nuclear spin interactions, such as phosphorous donors in silicon,\nopening up the possibility of fast and direct nuclear spin control in coupled\nspin systems."
    },
    {
        "anchor": "Subgap states at ferromagnetic and spiral-ordered magnetic chains in\n  two-dimensional superconductors. I. Continuum description: We consider subgap bands induced in a two-dimensional superconductor by a\ndensely packed chain of magnetic moments with ferromagnetic or spiral\nalignments. We show that by contrast with sparsely packed chains a consistent\ndescription requires that all wavelengths are taken into account for the\nscattering at the magnetic moments. The resulting subgap states are a\ncomposition of Yu-Shiba-Rusinov-type states and magnetic scattering states,\nwhose mixture becomes especially important to understand the nature and\ndimensional renormalization of gap closures for spiral magnetic alignments\nunder increasing scattering strength, particularly as the spiral becomes\ncommensurate with the Fermi wavelength. The results are fully analytic in the\nform of Green's functions and provide the tools for further analysis of the\nproperties of the subgap states.",
        "positive": "Shot noise free conductance reduction in quantum wires: We show that a shot noise free current at conductance below 2 e^2/h is\npossible in short interacting quantum wires without spin-polarization. Our\ncalculation is done for two exactly solvable limits of the ``Coulomb Tonks\ngas'', a one-dimensional gas of impenetrable electrons that can be realized in\nultra-thin quantum wires. In both cases we find that charge transport through\nsuch a wire is noiseless at zero temperature while the conductance is reduced\nto e^2/h."
    },
    {
        "anchor": "Quantum reflections and the shunting of polariton condensate wave\n  trains: implementation of a logic AND gate: We study the dynamics of polariton condensate wave trains that propagate\nalong a quasi one-dimensional waveguide. Through the application of tuneable\npotential barriers the propagation can be reflected and multiple reflections\nused to confine and store a propagating state. Energy-relaxation processes\nallow the delayed relaxation into a long-living coherent ground state. Aside\nthe potential routing of polariton condensate signals, the system forms an\nAND-type logic gate compatible with incoherent inputs.",
        "positive": "NMR studies of the topological insulator Bi2Te3: Te NMR studies were carried out for the bismuth telluride topological\ninsulator in a wide range from room temperature down to 12.5 K. The\nmeasurements were made on a Bruker Avance 400 pulse spectrometer. The NMR\nspectra were collected for the mortar and pestle powder sample and for single\ncrystalline stacks with orientations c parallel and perpendicular to field. The\nactivation energy responsible for thermal activation. The spectra for the stack\nwith c parallel to field showed some particular behavior below 91 K."
    },
    {
        "anchor": "An analytical study of electronic properties of ABC-stacking multilayer\n  graphene: We present an analytical model to study the electronic properties, including\nfull band structure, low energy dispersions around the Dirac point and density\nof states of the ABC-stacking $N$-layer graphene (ABCNLG). An ABCNLG can be\nsimulated by a linear atomic chain with $2N$ atoms. With only nearest-neighbor\ninter- and intra-layer hopping integrals taken into account, the Hamiltonian\nrepresentation is a complex $2N \\times 2N$ tridiagonal matrix $H_0$. Through a\nunitary transformation, we can reduce the $2N \\times 2N$ Hamiltonian matrix\ninto two real $N \\times N$ tridiagonal matrices $\\mathbb{H}_{s}$ and\n$\\mathbb{H}_{a}$, i. e., $H_0=\\mathbb{H}_{s} \\oplus \\mathbb{H}_{a} $. What's\nmore, the two matrices satisfy the relation $\\mathbb{H}_{a}=-\\mathbb{H}_{s}$.\nAs a result, energy spectrum associated with $\\mathbb{H}_{s}$ and\n$\\mathbb{H}_{s}$ have the relation $\\lambda_{a}=-\\lambda_{s}$. Such a\ncharacteristic is reflected on the energy dispersions and density of states.\nOur model can be applied to explore the basic properties of linear chain model\nand the eigenvalue problem of the tridiagonal matrices.",
        "positive": "Permanent Rabi oscillations in coupled exciton-photon systems with\n  PT-symmetry: We propose a physical mechanism which enables permanent Rabi oscillations in\ndriven-dissipative condensates of exciton-polaritons in semiconductor\nmicrocavities subjected to external magnetic fields. The method is based on\nincoherent excitonic reservoir engineering. We demonstrate that permanent\nnon-decaying oscillations may appear due to the parity-time (PT) symmetry of\nthe coupled exciton-photon system realised in a specific regime of pumping to\nthe exciton state and depletion of the reservoir. For effective non-zero\nexciton-photon detuning, permanent Rabi oscillations occur with unequal\namplitudes of exciton and photon components. Our predictions pave way to\nrealisation of integrated circuits based on exciton-polariton condensates."
    },
    {
        "anchor": "Graphene Nanoribbons with Smooth Edges Behave as Quantum Wires: Graphene nanoribbons with perfect edges are predicted to exhibit interesting\nelectronic and spintronic properties, notably quantum-confined bandgaps and\nmagnetic edge states. However, graphene nanoribbons produced by lithography\nhave, to date, exhibited rough edges and low-temperature transport\ncharacteristics dominated by defects, mainly variable range hopping between\nlocalized states in a transport gap near the Dirac point. Here, we report that\none- and two-layer nanoribbons quantum dots made by unzipping carbon\nnanotubes10 exhibit well-defined quantum transport phenomena, including Coulomb\nblockade, Kondo effect, clear excited states up to ~20meV, and inelastic\nco-tunnelling. Along with signatures of intrinsic quantum-confined bandgaps and\nhigh conductivities, our data indicate that the nanoribbons behave as clean\nquantum wires at low temperatures, and are not dominated by defects.",
        "positive": "Spin communication over 30 $\u03bc$m long channels of chemical vapor\n  deposited graphene on SiO$_2$: We demonstrate a high-yield fabrication of non-local spin valve devices with\nroom-temperature spin lifetimes of up to 3 ns and spin relaxation lengths as\nlong as 9 $\\mu$m in platinum-based chemical vapor deposition (Pt-CVD)\nsynthesized single-layer graphene on SiO$_2$/Si substrates. The spin-lifetime\nsystematically presents a marked minimum at the charge neutrality point, as\ntypically observed in pristine exfoliated graphene. However, by studying the\ncarrier density dependence beyond n ~ 5 x 10$^{12}$ cm$^{-2}$, via\nelectrostatic gating, it is found that the spin lifetime reaches a maximum and\nthen starts decreasing, a behavior that is reminiscent of that predicted when\nthe spin-relaxation is driven by spin-orbit interaction. The spin lifetimes and\nrelaxation lengths compare well with state-of-the-art results using exfoliated\ngraphene on SiO$_2$/Si, being a factor two-to-three larger than the best values\nreported at room temperature using the same substrate. As a result, the spin\nsignal can be readily measured across 30 $\\mu$m long graphene channels. These\nobservations indicate that Pt-CVD graphene is a promising material for\nlarge-scale spin-based logic-in-memory applications."
    },
    {
        "anchor": "Quadrupolar Excitons and Hybridized Interlayer Mott Insulator in a\n  Trilayer Moir\u00e9 Superlattice: Transition metal dichalcogenide (TMDC) moir\\'e superlattices, owing to the\nmoir\\'e flatbands and strong correlation, can host periodic electron crystals\nand fascinating correlated physics. The TMDC heterojunctions in the type-II\nalignment also enable long-lived interlayer excitons that are promising for\ncorrelated bosonic states, while the interaction is dictated by the asymmetry\nof the heterojunction. Here we demonstrate a new excitonic state, quadrupolar\nexciton, in a symmetric WSe2-WS2-WSe2 trilayer moir\\'e superlattice. The\nquadrupolar excitons exhibit a quadratic dependence on the electric field,\ndistinctively different from the linear Stark shift of the dipolar excitons in\nheterobilayers. This quadrupolar exciton stems from the hybridization of WSe2\nvalence moir\\'e flatbands. The same mechanism also gives rise to an interlayer\nMott insulator state, in which the two WSe2 layers share one hole laterally\nconfined in one moir\\'e unit cell. In contrast, the hole occupation probability\nin each layer can be continuously tuned via an out-of-plane electric field,\nreaching 100% in the top or bottom WSe2 under a large electric field,\naccompanying the transition from quadrupolar excitons to dipolar excitons. Our\nwork demonstrates a trilayer moir\\'e system as a new exciting playground for\nrealizing novel correlated states and engineering quantum phase transitions.",
        "positive": "Interaction-Enhanced Coherence Between Two-Dimensional Dirac Layers: We estimate the strength of interaction-enhanced coherence between two\ngraphene or topological insulator surface-state layers by solving\nimaginary-axis gap equations in the random phase approximation. Using a\nself-consistent treatment of dynamic screening of Coulomb interactions in the\ngapped phase, we show that the excitonic gap can reach values on the order of\nthe Fermi energy at strong interactions. The gap is discontinuous as a function\nof interlayer separation and effective fine structure constant, revealing a\nfirst order phase transition between effectively incoherent and interlayer\ncoherent phases. To achieve the regime of strong coherence the interlayer\nseparation must be smaller than the Fermi wavelength, and the extrinsic\nscreening of the medium embedding the Dirac layers must be negligible. In the\ncase of a graphene double-layer we comment on the supportive role of the remote\n$\\pi$-bands neglected in the two-band Dirac model."
    },
    {
        "anchor": "Rescaling of Applied Oscillating Voltages in Small Josephson Junctions: The standard theory of dynamical Coulomb blockade [$P(E)$ theory] in\nultra-small tunnel junctions has been formulated on the basis of phase-phase\ncorrelations by several authors. It was recently extended by several\nexperimental and theoretical works to account for novel features such as\nelectromagnetic environment-based renormalization effects. Despite this\nprogress, aspects of the theory remain elusive especially in the case of linear\narrays. Here, we apply path integral formalism to re-derive the Cooper-pair\ncurrent and the BCS quasi-particle current in single small Josephson junctions\nand extend it to include long Josephson junction arrays as effective single\njunctions. We consider renormalization effects of applied oscillating voltages\ndue to the impedance environment of a single junction as well as its\nimplication to the array. As is the case in the single junction, we find that\nthe amplitude of applied oscillating electromagnetic fields is renormalized by\nthe same complex-valued weight $\\Xi(\\omega) = |\\Xi(\\omega)|\\exp i\\eta(\\omega)$\nthat rescales the environmental impedance in the $P(E)$ function. This weight\nacts as a linear response function for applied oscillating electromagnetic\nfields driving the quantum circuit, leading to a mass gap in the thermal\nspectrum of the electromagnetic field. The mass gap can be modeled as a pair of\nexotic `particle' excitation with quantum statistics determined by the argument\n$\\eta(\\omega)$. In the case of the array, this pair corresponds to a bosonic\ncharge soliton/anti-soliton pair injected into the array by the electromagnetic\nfield. Possible application of these results is in dynamical Coulomb blockade\nexperiments where long arrays are used as electromagnetic power detectors.",
        "positive": "Experimental Signatures of the Inverted Phase in InAs/GaSb Coupled\n  Quantum Wells: Transport measurements are performed on InAs/GaSb double quantum wells at\nzero and finite magnetic fields applied parallel and perpendicular to the\nquantum wells. We investigate a sample in the inverted regime where electrons\nand holes coexist, and compare it with another sample in the non-inverted\nsemiconducting regime. Activated behavior in conjunction with a strong\nsuppression of the resistance peak at the charge neutrality point in a parallel\nmagnetic field attest to the topological hybridization gap between electron and\nhole bands in the inverted sample. We observe an unconventional Landau level\nspectrum with energy gaps modulated by the magnetic field applied perpendicular\nto the quantum wells. This is caused by strong spin-orbit interaction provided\njointly by the InAs and the GaSb quantum wells."
    },
    {
        "anchor": "Window functions and sigmoidal behaviour of memristive systems: A common approach to model memristive systems is to include empirical window\nfunctions to describe edge effects and non-linearities in the change of the\nmemristance. We demonstrate that under quite general conditions, each window\nfunction can be associated with a sigmoidal curve relating the normalised\ntime-dependent memristance to the time integral of the input. Conversely, this\nexplicit relation allows us to derive window functions suitable for the\nmesoscopic modelling of memristive systems from a variety of well-known\nsigmoidals. Such sigmoidal curves are defined in terms of measured variables\nand can thus be extracted from input and output signals of a device and then\ntransformed to its corresponding window. We also introduce a new generalised\nwindow function that allows the flexible modelling of asymmetric edge effects\nin a simple manner.",
        "positive": "Highly efficient UV detection in a metal-semiconductor-metal detector\n  with epigraphene: We show that epitaxial graphene on silicon carbide (epigraphene) grown at\nhigh temperatures (T > 1850 {\\deg}C) readily acts as material for implementing\nsolar-blind ultraviolet (UV) detectors with outstanding performance. We present\ncentimeter-sized epigraphene metal-semiconductor-metal (MSM) detectors with\npeak external quantum efficiency of ~ 85% for wavelengths 250-280 nm,\ncorresponding to nearly 100% internal quantum efficiency when accounting for\nreflection losses. Zero bias operation is possible in asymmetric devices, with\nthe responsivity to UV remaining as high as R = 134 mA/W, making this a\nself-powered detector. The low dark currents Io ~50 fA translate into an\nestimated record high specific detectivity D = 3.5 x 10^15 Jones. The\nperformance that we demonstrate, together with material reproducibility,\nrenders epigraphene technologically attractive to implement high-performance\nplanar MSM devices with a low processing effort, including multi-pixel UV\nsensor arrays, suitable for a number of practical applications."
    },
    {
        "anchor": "Ring-shaped spatial pattern of exciton luminescence formed due to the\n  hot carrier transport in a locally photoexcited electron-hole bilayer: A consistent explanation of the formation of a ring-shaped pattern of exciton\nluminescence in GaAs/AlGaAs double quantum wells is suggested. The pattern\nconsists of two concentric rings around the laser excitation spot. It is shown\nthat the luminescence rings appear due to the in-layer transport of hot charge\ncarriers at high photoexcitation intensity. Interestingly, one of two causes of\nthis transport might involve self-organized criticality (SOC) that would be the\nfirst case of the SOC observation in semiconductor physics. We test this cause\nin a many-body numerical model by performing extensive molecular dynamics\nsimulations. The results show good agreement with experiments. Moreover, the\nsimulations have enabled us to identify the particular kinetic processes\nunderlying the formation of each of these two luminescence rings.",
        "positive": "Bloch theorem dictated wave chaos in microcavity crystals: Universality class of wave chaos emerges in many areas of science, such as\nmolecular dynamics, optics, and network theory. In this work, we generalize the\nwave chaos theory to cavity lattice systems by discovering the intrinsic\ncoupling of the crystal momentum to the internal cavity dynamics. The\ncavity-momentum locking substitutes the role of the deformed boundary shape in\nthe ordinary single microcavity problem, providing a new platform for the in\nsitu study of microcavity light dynamics. The transmutation of wave chaos in\nperiodic lattices leads to a phase space reconfiguration that induces a\ndynamical localization transition. The degenerate scar-mode spinors hybridize\nand non-trivially localize around regular islands in phase space. In addition,\nwe find that the momentum coupling becomes maximal at the Brillouin zone\nboundary, so the intercavity chaotic modes coupling and wave confinement are\nsignificantly altered. Our work pioneers the study of intertwining wave chaos\nin periodic systems and provide useful applications in light dynamics control."
    },
    {
        "anchor": "Magnetized Topological Insulator Multilayers: We discuss the magnetic and topological properties of bulk crystals and\nquasi-two-dimensional thin films formed by stacking intrinsic magnetized\ntopological insulator ( for example Mn(Sb$_{x}$Bi$_{1-x}$)$_2$X$_4$ with X =\nSe,Te, including MnBi$_2$Te$_4$) septuple layers and topological insulator\nquintuple layers in arbitrary order. Our analysis makes use of a simplified\nmodel that retains only Dirac-cone degrees of freedom on both surfaces of each\nseptuple or quintuple layer. We demonstrate the model's applicability and\nestimate its parameters by comparing with {\\it ab initio }\ndensity-functional-theory(DFT) calculations. We then employ the coupled Dirac\ncone model to provide an explanation for the dependence of thin-film\nproperties, particularly the presence or absence of the quantum anomalous Hall\neffect, on film thickness, magnetic configuration, and stacking arrangement,\nand to comment on the design of Weyl superlattices.",
        "positive": "Ground State Resonant Two-Photon Transitions in Wurtzite GaN/AlN Quantum\n  Dots: Two-photon transition rates are investigated in resonance to the ground state\nin wurtzite GaN/AlN quantum dots. The ground state transition is two-photon\nallowed because of the electron-hole separation inherent to polar wurtzite\nIII-nitride heterostructures. We show that this built-in parity breaking\nmechanism can allow deterministic triggering of single-photon emission via\ncoherent two-photon excitation. Radiative lifetimes obtained for single-photon\nrelaxation are in good agreement with available time-resolved\nmicro-photoluminescence experiments, indicating the reliability of the employed\ncomputational framework based on 8-band k.p-wavefunctions. Two-photon\nsingly-induced emission is explored in terms of possible cavity and\nnon-degeneracy enhancement of two-photon processes."
    },
    {
        "anchor": "Topological phase transitions in the photonic spin Hall effect: The recent synthesis of two-dimensional staggered materials opens up\nburgeoning opportunities to study optical spin-orbit interactions in\nsemiconducting Dirac-like systems. We unveil topological phase transitions in\nthe photonic spin Hall effect in the graphene family materials. It is shown\nthat an external static electric field and a high frequency circularly\npolarized laser allow for active on-demand manipulation of electromagnetic beam\nshifts. The spin Hall effect of light presents a rich dependence with radiation\ndegrees of freedom, material properties, and features non-trivial topological\nproperties. We discover that photonic Hall shifts are sensitive to spin and\nvalley properties of the charge carries, providing a unprecedented pathway to\ninvestigate spintronics and valleytronics in staggered 2D semiconductors.",
        "positive": "Radiative thermal switch exploiting hyperbolic surface phonon polaritons: We study the radiative heat flux between two nanoparticles in close vicinity\nto the natural hyperbolic material hBN with its optical axis oriented parallel\nto the interface. We show that the heat flux between the nanoparticles can be\nefficiently modulated when rotating the nanoparticles due to the coupling to\nthe highly directional hyperbolic surface modes in hBN. Finally, we discuss the\nthickness and distance dependence of this effect."
    },
    {
        "anchor": "Single-Electron Effects in a Coupled Dot-Ring System: Aharonov-Bohm oscillations are studied in the magnetoconductance of a\nmicron-sized open quantum ring coupled capacitively to a Coulomb-blockaded\nquantum dot. As the plunger gate of the dot is modulated and tuned through a\nconductance resonance, the amplitude of the Aharonov-Bohm oscillations in the\ntransconductance of the ring displays a minimum. We demonstrate that the effect\nis due to a single-electron screening effect, rather than to dephasing.\nAharonov-Bohm oscillations in a quantum ring can thus be used for the detection\nof single charges.",
        "positive": "Crossover between two different Kondo couplings in side-coupled double\n  quantum dots: We study the Kondo effect in side-coupled double quantum dots with particular\nfocus on the crossover between two distinct singlet ground states, using the\nnumerical renormalization group. The crossover occurs as the quantized energy\nlevel of the embedded dot, which is connected directly to the leads, is varied.\nIn the parameter region where the embedded dot becomes almost empty or doubly\noccupied, the local moment emerging in the other dot at the side of the path\nfor the current is screened via a superexchange process by the conduction\nelectrons tunneling through the embedded dot. In contrast, in the other region\nwhere the embedded dot is occupied by a single electron, the local moment\nemerges also in the embedded dot, and forms a singlet bond with the moment in\nthe side dot. Furthermore, we derive two different Kondo Hamiltonians for these\nlimits carrying out the Schrieffer-Wolff transformation, and show that they\ndescribe the essential feature of the screening for each case."
    },
    {
        "anchor": "Solution-phase single-particle spectroscopy for probing multi-polaronic\n  dynamics in quantum emitters at femtosecond resolution: The development of many optical quantum technologies depends on the\navailability of solid-state single quantum emitters with near-perfect optical\ncoherence. However, a standing issue that limits systematic improvement is the\nsignificant sample heterogeneity and lack of mechanistic understanding of\nmicroscopic energy flow at the single emitter level and ultrafast timescales.\nHere we develop solution-phase single-particle pump-probe spectroscopy with\nphoton correlation detection that captures sample-averaged dynamics in single\nmolecules and/or defect states with unprecedented clarity at femtosecond\nresolution. We apply this technique to single quantum emitters in\ntwo-dimensional hexagonal boron nitride, which suffers from significant\nheterogeneity and low quantum efficiency. From millisecond to nanosecond\ntimescales, the translation diffusion, metastable-state-related bunching\nshoulders, rotational dynamics, and antibunching features are disentangled by\ntheir distinct photon-correlation timescales, which collectively quantify the\nnormalized two-photon emission quantum yield. Leveraging its femtosecond\nresolution, spectral selectivity and ultralow noise (two orders of magnitude\nimprovement over solid-state methods), we visualize electron-phonon coupling in\nthe time domain at the single defect level, and discover the acceleration of\npolaronic formation driven by multi-electron excitation. Corroborated with\nresults from a theoretical polaron model, we show how this translates to\nsample-averaged photon fidelity characterization of cascaded emission\nefficiency and optical decoherence time. Our work provides a framework for\nultrafast spectroscopy in single emitters, molecules, or defects prone to\nphotoluminescence intermittency and heterogeneity, opening new avenues of\nextreme-scale characterization and synthetic improvements for quantum\ninformation applications.",
        "positive": "Heat capacity of suspended phonon cavities: We present a detailed analysis of the vibrational spectrum and heat capacity\nof suspended mesoscopic dielectric plates, for various thickness-to-side ratios\nat sub-Kelvin temperatures. The vibrational modes of the suspended cavity are\naccurately obtained from the three-dimensional (3D) elastic equations in the\nsmall strain limit and their frequencies assigned to the cavity phonon modes.\nThe calculations demonstrate that the heat capacity of realistic quasi-2D\nphonon cavities approach the linear dependence on T at sub-Kelvin temperatures.\nThe behavior is more pronounced for the thinnest cavities, but takes place also\nfor moderately thick structures, with thickness-to-side ratios $\\gamma$=0.1 to\n0.2. It is also demonstrated that the heat capacity of the suspended phonon\ncavities is invariant under the product of the temperature (T) with a\ncharacteristic lateral dimension (L) of the sample. The present results\nestablish a lower bound for the heat capacity of suspended mesoscopic\nstructures and indicate the emergence of the quantum mechanical regime in the\ndynamics of bounded phonon cavities."
    },
    {
        "anchor": "A hole-Cr$^{+}$ nano-magnet in a semiconductor quantum dot: We study a new diluted magnetic semiconductor system based on the spin of the\nionized acceptor Cr$^+$. We show that the negatively charged Cr$^+$ ion, an\nexcited state of the Cr in II-VI semiconductor, can be stable when inserted in\na CdTe quantum dot (QD). The Cr$^+$ attracts a heavy-hole in the QD and form a\nstable hole-Cr$^+$ complex. Optical probing of this system reveals a\nferromagnetic coupling between heavy-holes and Cr$^+$ spins. At low\ntemperature, the thermalization on the ground state of the hole-Cr$^+$ system\nwith parallel spins prevents the optical recombination of the excess electron\non the 3$d$ shell of the atom. We study the dynamics of the nano-magnet formed\nby the hole-Cr$^+$ exchange interaction. The ferromagnetic ground states with\nM$_z$=$\\pm$4 can be controlled by resonant optical pumping and a spin\nrelaxation time in the 20 $\\mu$s range is obtained at T=4.2 K. This spin memory\nat zero magnetic field is limited by the interaction with phonons.",
        "positive": "Detangling Extrinsic and Intrinsic Hysteresis for Detecting Dynamic\n  Switch of Electric Dipoles using Graphene Field-Effect Transistors on\n  Ferroelectric Gates: A transition in source-drain current vs back gate voltage ID - VBG\ncharacteristics from extrinsic polar molecule dominant hysteresis to\nanti-hysteresis induced by an oxygen deficient surface layer that is intrinsic\nto the ferroelectric thin films has been observed on graphene field-effect\ntransistors on Pb0.92La0.08Zr0.52Ti0.48O3 gates GFET/PLZT-Gate during a vacuum\nannealing process developed to systematically remove the polar molecules\nadsorbed on the GFET channel surface. This allows detangle of the extrinsic and\nintrinsic hysteresis on GFET/PLZT-gate devices and detection of the dynamic\nswitch of electric dipoles using GFETs, taking advantage of their high gating\nefficiency on ferroelectric gate. A model of the charge trapping and pinning\nmechanism is proposed to successfully explain the transition. In response to\npulsed VBG trains of positive, negative, as well as alternating polarities,\nrespectively, the source-drain current ID variation is instantaneous with the\nresponse amplitude following the ID - VBG loops measured by DC VBG with\nconsideration of the remnant polarization after a given VBG pulse when the gate\nelectric field exceeds the coercive field of the PLZT. A detection sensitivity\nof around 212 dipole/um2 has been demonstrated at room temperature, suggesting\nthe GFET/ferroelectric-gate devices provide a promising high-sensitivity scheme\nfor uncooled detection of electrical dipole dynamic switch."
    },
    {
        "anchor": "Manipulation of the Dirac cones and the anomaly in the graphene related\n  quantum Hall effect: The quantum Hall effect in graphene is regarded to be involving half-integer\ntopological numbers associated with the massless Dirac particle, this is\nusually not apparent due to the doubling of the Dirac cones. Here we\ntheoretically consider two classes of lattice models in which we manipulate the\nDirac cones with either (a) two Dirac points that have mutually different\nenergies, or (b) multiple Dirac cones having different Fermi velocities. We\nhave shown, with an explicit calculation of the topological (Chern) number for\ncase (a) and with an adiabatic argument for case (b) that the results are\nconsistent with the picture that a single Dirac fermion contributes the\nhalf-odd integer series (... -3/2, -1/2, 1/2, 3/2, ...) to the Hall\nconductivity when the Fermi energy traverses the Landau levels.",
        "positive": "Free energies of triply and quadruply degenerate electron ladder spectra: The electronic free energies in metal clusters are calculated based on a\nsimple ladder spectrum for the level degeneracies three and four, and compared\nwith the known results for degeneracies one and two. The low temperature and\nthe asymptotic high temperature results for free energy differences are\ngeneralized to ladder spectra of any degeneracy. Remarkably, free energy\ndifferences do not approach zero at high energies for size-independent Fermi\nenergies."
    },
    {
        "anchor": "Electron Correlations in Partially Filled Lowest and Excited Landau\n  Levels: The electron correlations near the half-filling of the lowest and excited\nLandau levels (LL's) are studied using numerical diagonalization. It is shown\nthat in the low lying states electrons avoid pair states with relative angular\nmomenta ${\\cal R}$ corresponding to positive anharmonicity of the interaction\npseudopotential $V({\\cal R})$. In the lowest LL, the super-harmonic behavior of\n$V({\\cal R})$ causes Laughlin correlations (avoiding pairs with ${\\cal R}=1$)\nand the Laughlin-Jain series of incompressible ground states. In the first\nexcited LL, $V({\\cal R})$ is harmonic at short range and a different series of\nincompressible states results. Similar correlations occur in the paired\nMoore-Read $\\nu={5\\over2}$ state and in the $\\nu={7\\over3}$ and ${8\\over3}$\nstates, all having small total parentage from ${\\cal R}=1$ and 3 and large\nparentage from ${\\cal R}=5$. The $\\nu={7\\over3}$ and ${8\\over3}$ states are\ndifferent from Laughlin $\\nu={1\\over3}$ and ${2\\over3}$ states and, in finite\nsystems, occur at a different LL degeneracy (flux). The series of Laughlin\ncorrelated states of electron pairs at $\\nu=2+2/(q_2+2)={8\\over3}$,\n${5\\over2}$, ${12\\over5}$, and ${7\\over3}$ is proposed, although only in the\n$\\nu={5\\over2}$ state pairing has been confirmed numerically. In the second\nexcited LL, $V({\\cal R})$ is sub-harmonic at short range and (near the\nhalf-filling) the electrons group into spatially separated larger $\\nu=1$\ndroplets to minimize the number of strongly repulsive pair states at ${\\cal\nR}=3$ and 5.",
        "positive": "Intermediate state switching dynamics in magnetic double layer\n  nanopillars grown by molecular beam epitaxy: We observe a stable intermediate resistance switching state in the current\nperpendicular to plane geometry for all Co/Cu/Co double layer nanopillar\njunctions grown by molecular beam epitaxy. This novel state has a resistance\nbetween the resistances of the parallel and antiparallel alignment of both\nCo-layer magnetizations. The state, which originates from an additional\nin-plane magnetic easy axis, can be reached by spin transfer torque switching\nor by an external magnetic field. In addition to spin torque-induced coherent\nsmall-angle spin wave modes we observe a broad microwave emission spectrum. The\nlatter is attributed to incoherent magnetic excitations that lead to a\nswitching between the intermediate state and the parallel or antiparallel\nalignment of both ferromagnetic layers. We conclude that the additional\nmagnetic easy axis suppresses a stable trajectory of coherent large-angle\nprecession, which is not observed in our samples."
    },
    {
        "anchor": "Monopole topological resonators: Among the many far-reaching consequences of the potential existence of a\nmagnetic monopole, it induces topological zero modes in the Dirac equation,\nwhich were derived by Jackiw and Rebbi 46 years ago and have been elusive ever\nsince. Here, we show that the monopole and multi-monopole solutions can be\nconstructed in the band theory by coupling the three-dimensional Dirac points\nin hedgehog spatial configurations through Dirac-mass engineering. We then\nexperimentally demonstrate such a monopole bound state in a\nstructurally-modulated acoustic crystal as a cavity device. These monopole\nresonators not only support an arbitrary number of degenerate mid-gap modes,\nbut also offer the optimal single-mode behavior possible -- whose modal spacing\nis inversely proportional to the cubic root of the modal volume. Our work\ncompletes the kink-vortex-monopole trilogy of zero modes and provides the\nlargest free spectral range for sizable resonators.",
        "positive": "Collective intersubband transitions in quantum wells: a comparative\n  density-functional study: We use time-dependent (current) density functional theory to study collective\ntransitions between the two lowest subbands in GaAs/AlGaAs quantum wells. We\nfocus on two systems where experimental results are available: a wide single\nand a narrow asymmetric double well. The aim is to calculate frequency and\nlinewidth of collective electronic modes damped via electron-electron\ninteraction only. Since Landau damping is not effective here, the dominant\ndamping mechanism involves dynamical exchange-correlation effects such as\nmultipair production. To capture these effects, one has to go beyond the widely\nused adiabatic local density approximation (ALDA) and include retardation. We\nperform a comparative study of two approaches which fall in this category: the\ndynamical extension of the ALDA by Gross and Kohn, and a more recent method\nwhich treats exchange and correlation beyond the ALDA as viscoelastic stresses\nin the electron liquid. We find that the former method is more robust: it\nperforms similarly for strongly different degrees of collectivity of the\nelectronic motion. Results for quantum wells compare reasonably to experiment,\nwith a tendency towards overdamping. By contrast, the viscoelastic approach is\nsuperior for systems where the electron dynamics is predominantly collective,\nbut breaks down if the local velocity field is too rapidly varying, as in the\ncase of a single-electron-like behavior such as tunneling through a potential\nbarrier."
    },
    {
        "anchor": "Tunable plasmon modes in doped AA-stacked bilayer graphene: We study plasmon modes in doped AA-stacked bilayer graphene (BLG) within the\nnearest-neighbor tight-binding and the random phase approximation. We obtain\nclosed analytical expressions for the polarizability function which are used to\nobtain the low-energy dispersion relations of and the numerical results for\nboth acoustic and optical plasmon modes. Our result reveal the potential of\nAA-stacked BLG to be used as a tunable plasmonic device. In particular we find\nthat the long-wavelength acoustic plasmon disperse as\n$\\omega_{+}\\approx\\sqrt{max(|\\mu|,t_{1})q}$ with a phase space which shrinks\nand vanishes as the chemical potential approaches the interlayer hopping\nenergy, preventing the existence of long-lived acoustic plasmon. Furthermore,\nwe show that AA-stacked BLG support coherent optical plasmon only when the\ncondition $(1+\\frac{g_{\\sigma}g_{v}e^{2}t_{1}d}{\\kappa\nv_{F}^{2}}\\frac{|\\mu|}{t_{1}})^{1/2}<\\frac{|\\mu|}{t_{1}}$ is satisfied,\nspecially indicating Landau damping of the optical plasmon in undoped AA-staked\nBLG even at long-wavelength limit. We also find that the optical plasmon mode\ndisperses as $\\omega_{-}\\approx \\Delta+Cq^{2}$ with constants that can be tuned\nby tuning the chemical potential.",
        "positive": "Tunneling Spin Injection into Single Layer Graphene (Supplementary\n  Information): We achieve tunneling spin injection from Co into single layer graphene (SLG)\nusing TiO2 seeded MgO barriers. A non-local magnetoresistance ({\\Delta}RNL) of\n130 {\\Omega} is observed at room temperature, which is the largest value\nobserved in any material. Investigating {\\Delta}RNL vs. SLG conductivity from\nthe transparent to the tunneling contact regimes demonstrates the contrasting\nbehaviors predicted by the drift-diffusion theory of spin transport.\nFurthermore, tunnel barriers reduce the contact-induced spin relaxation and are\ntherefore important for future investigations of spin relaxation in graphene."
    },
    {
        "anchor": "Electronic Aharonov-Bohm Effect Induced by Quantum Vibrations: Mechanical displacements of a nanoelectromechanical system (NEMS) shift the\nelectron trajectories and hence perturb phase coherent charge transport through\nthe device. We show theoretically that in the presence of a magnetic feld such\nquantum-coherent displacements may give rise to an Aharonov-Bohm-type of\neffect. In particular, we demonstrate that quantum vibrations of a suspended\ncarbon nanotube result in a positive nanotube magnetoresistance, which\ndecreases slowly with the increase of temperature. This effect may enable one\nto detect quantum displacement fluctuations of a nanomechanical device.",
        "positive": "Electron spin inversion in gated silicene nanoribbons: We study locally gated silicene nanoribbons as spin active devices. We find\nthat the gated segments of nanoribbons with zigzag edge can be used to perform\na spin inversion for the electron spins injected with an in-plane orientation.\nThe strong intrinsic spin-orbit coupling for low Fermi energy in presence of an\nexternal vertical electric field provides a fast spin precession around the\naxis perpendicular to the silicene plane. The spin inversion length can be as\nsmall as 10 nm. On the other hand in the armchair nanoribbons the spin\ninversion occurs via the Rashba effect which is weak and the spin inversion\nlengths are of the order of $\\mu$m."
    },
    {
        "anchor": "Nanomechanical characterization of quantum interference in a topological\n  insulator nanowire: The discovery of two-dimensional gapless Dirac fermions in graphene and\ntopological insulators (TI) has sparked extensive ongoing research toward\napplications of their unique electronic properties. The gapless surface states\nin three-dimensional insulators indicate a distinct topological phase of matter\nwith a non-trivial Z2 invariant that can be verified by angle-resolved\nphotoemission spectroscopy or magnetoresistance quantum oscillation. In TI\nnanowires, the gapless surface states exhibit Aharonov-Bohm (AB) oscillations\nin conductance, with this quantum interference effect accompanying a change in\nthe number of transverse one-dimensional modes in transport. Thus, while the\ndensity of states (DOS) of such nanowires is expected to show such AB\noscillation, this effect has yet to be observed. Here, we adopt nanomechanical\nmeasurements that reveal AB oscillations in the DOS of a topological insulator.\nThe TI nanowire under study is an electromechanical resonator embedded in an\nelectrical circuit, and quantum capacitance effects from DOS oscillation\nmodulate the circuit capacitance thereby altering the spring constant to\ngenerate mechanical resonant frequency shifts. Detection of the quantum\ncapacitance effects from surface-state DOS is facilitated by the small\neffective capacitances and high quality factors of nanomechanical resonators,\nand as such the present technique could be extended to study diverse quantum\nmaterials at nanoscale.",
        "positive": "Spin decoherence due to a randomly fluctuating spin bath: We study the decoherence of a spin in a quantum dot due to its hyperfine\ncoupling to a randomly fluctuating bath of nuclear spins. The system is\nmodelled by the central spin model with the spin bath initially being at\ninfinite temperature. We calculate the spectrum and time evolution of the\ncoherence factor using a Monte Carlo sampling of the exact eigenstates obtained\nvia the algebraic Bethe ansatz. The exactness of the obtained eigenstates\nallows us to study the non-perturbative regime of weak magnetic fields in a\nfull quantum mechanical treatment. In particular, we find a large non-decaying\nfraction in the zero-field limit. The crossover from strong to weak fields is\nsimilar to the decoherence starting from a pure initial bath state treated\npreviously. We compare our results to a simple semiclassical picture [Merkulov\net al., Phys. Rev. B 65, 205309 (2002)] and find surprisingly good agreement.\nFinally, we discuss the effect of weakly coupled spins and show that they will\neventually lead to complete decoherence."
    },
    {
        "anchor": "A strain-tunable quantum dot embedded in a nanowire antenna: We demonstrate an elastically-tunable self-assembled quantum dot in a\nnanowire antenna that emits single photons with resolution-limited spectral\nlinewidths. The single-photon device is comprised of a single quantum dot\nembedded in a top-down fabricated nanowire waveguide integrated onto a\npiezoelectric actuator. Non-resonant excitation leads to static (fluctuating)\ncharges likely at the nanowire surface, causing DC Stark shifts (inhomogeneous\nbroadening); for low excitation powers, the effects are not observed and\nresolution-limited linewidths are obtained. Despite significant strain-field\nrelaxation in the high-aspect-ratio nanowires, we achieve up to 1.2 meV tuning\nof a dot's transition energy. Single-photon sources with high brightness,\nresolution-limited linewidths, and wavelength tunability are promising for\nfuture quantum technologies.",
        "positive": "Twisted Fermi surface of a thin-film Weyl semimetal: The Fermi surface of a conventional two-dimensional electron gas is\nequivalent to a circle, up to smooth deformations that preserve the orientation\nof the equi-energy contour. Here we show that a Weyl semimetal confined to a\nthin film with an in-plane magnetization and broken spatial inversion symmetry\ncan have a topologically distinct Fermi surface that is twisted into a\n$\\mbox{figure-8}$ $-$ opposite orientations are coupled at a crossing which is\nprotected up to an exponentially small gap. The twisted spectral response to a\nperpendicular magnetic field $B$ is distinct from that of a deformed Fermi\ncircle, because the two lobes of a \\mbox{figure-8} cyclotron orbit give\nopposite contributions to the Aharonov-Bohm phase. The magnetic edge channels\ncome in two counterpropagating types, a wide channel of width $\\beta\nl_m^2\\propto 1/B$ and a narrow channel of width $l_m\\propto 1/\\sqrt B$ (with\n$l_m=\\sqrt{\\hbar/eB}$ the magnetic length and $\\beta$ the momentum separation\nof the Weyl points). Only one of the two is transmitted into a metallic\ncontact, providing unique magnetotransport signatures."
    },
    {
        "anchor": "Electric field controlled magnetization and transport properties of\n  La0.7Ca0.3MnO3 ultrathin film: We have investigated the effect of electric field control on the\nmagnetization and the transport properties in La0.7Ca0.3MnO3 (LCMO) ultrathin\nfilm (~10 nm) by using it as the semiconductor channel material of a\nprototypical field effect device and SiO2 as dielectric gate. A large\nelectroresistance (ER) of ~78% at Vg = -8 V is found in LCMO at 200 K. The\ndirect magnetization measurements confirm the formation of a large\nferromagnetic phase with the increase in the applied gate voltage at 200 K.",
        "positive": "Screening, Friedel oscillations, RKKY interaction, and Drude transport\n  in anisotropic two-dimensional systems: We investigate the effect of the mass anisotropy on Friedel Oscillations,\nRuderman-Kittel-Kasuya-Yosida (RKKY) interaction, screening properties, and\nBoltzmann transport in two dimensional (2D) metallic and doped semiconductor\nsystems. We calculate the static polarizability and the dielectric function\nwithin the random phase approximation with the mass anisotropy fully taken into\naccount without making any effective isotropic approximation in the theory. We\nfind that carrier screening exhibits an isotropic behavior for small momenta\ndespite the anisotropy of the system, and becomes strongly anisotropic above a\ncertain threshold momentum. Such an anisotropy of screening leads to\nanisotropic Friedel oscillations, and an anisotropic RKKY interaction\ncharacterized by a periodicity dependent on the direction between the localized\nmagnetic moments. We also explore the disorder limited dc transport properties\nin the presence of mass anisotropy based on the Boltzmann transport theory.\nInterestingly, we find that the anisotropy ratio of the short range disorder\nlimited resistivity along the heavy- and light-mass directions is always the\nsame as the mass anisotropy ratio whereas for the long range disorder limited\nresistivity the anisotropy ratio is the same as the mass ratio only in the low\ndensity limit, and saturates to the square root of the mass ratio in the high\ndensity limit. Our theoretical work should apply to many existing and\nto-be-discovered anisotropic 2D systems."
    },
    {
        "anchor": "Superradiant terahertz emission by dipolaritons: Dipolaritons are mixed light-matter quasiparticles formed in double quantum\nwells embedded in microcavities. Due to resonant coupling between direct and\nindirect excitons via electronic tunnelling, dipolaritons possess large dipole\nmoments. Resonant excitation of the cavity mode by a short pulse of light\ninduces oscillations of the indirect exciton density with a characteristic\nfrequency of Rabi flopping. This results in oscillations of classical Hertz\ndipoles array which generate supperradiant emission on a terahertz (THz)\nfrequency. Resulting THz signal may be enhanced using the supplementary THz\ncavity in the weak coupling regime.",
        "positive": "Topological Valley Currents in Bilayer Graphene/Hexagonal Boron Nitride\n  Superlattices: Graphene superlattices have recently been attracting growing interest as an\nemergent class of quantum metamaterials. In this paper, we report the\nobservation of nonlocal transport in bilayer graphene (BLG) superlattices\nencapsulated between two hexagonal boron nitride (hBN) layers, which formed\nhBN/BLG/hBN moir\\'e superlattices. We then employed these superlattices to\ndetect a long-range charge-neutral valley current using an all-electrical\nmethod. The moir\\'e superlattice with broken inversion symmetry leads to a hot\nspot with Berry curvature accumulating at the charge neutral point (CNP), and\nit harbors satellites of the CNP. We observed nonlocal resistance on the order\nof 1 $\\text{k}\\Omega$, which obeys a scaling relation. This nonlocal resistance\nevolves from the quantum Hall effect but without magnetic field/time-reversal\nsymmetry breaking, which is associated with a hot-spot-induced topological\nvalley current. This study should pave the way to developing a\nBerry-phase-sensitive probe to detect hot spots in gapped Dirac materials with\ninversion-symmetry breaking."
    },
    {
        "anchor": "Numerical analysis of a hysteresis model in perovskite solar cells: Previously, we proposed that the polarization and capacitive charge in\n\\ce{CH3NH3PbI3} screens the external electric field that hinders charge\ntransport. We argue here that this screening effect is in significant part\nresponsible for the power conversion characteristics and hysteresis in\n\\ce{CH3NH3PbI3} photovoltaic cells. In this paper, we implement capacitive\ncharge and polarization charge into the numerical model that we have developed\nfor perovskite solar cells. Fields induced by these two charges screen the\napplied hindering field, promote charge transport, and improve solar cell's\nperformance, especially in solar cells with short diffusion lengths. This is\nthe reason why perovskite solar cells made from simple fabrication methods can\nachieve high performance. More importantly, with relaxations of capacitive\ncharge and polarization charge, we quantitatively reproduce experimental\n\"anomalous\" hysteresis J-V curves. This reveals that both polarization\nrelaxation and ions relaxation could contribute to anomalous hysteresis in\nperovskite solar cells.",
        "positive": "Helicoidal Fields and Spin Polarized Currents in CNT-DNA Hybrids: We report on theoretical studies of electronic transport in the archetypical\nmolecular hybrid formed by DNA wrapped around single-walled carbon nanotubes\n(CNTs). Using a Green's function formalism in a $\\pi$-orbital tight-binding\nrepresentation, we investigate the role that spin-orbit interactions play on\nthe CNT in the case of the helicoidal electric field induced by the polar\nnature of the adsorbed DNA molecule. We find that spin polarization of the\ncurrent can take place in the absence of magnetic fields, depending strongly on\nthe direction of the wrapping and length of the helicoidal field. These\nfindings open new routes for using CNTs in spintronic devices."
    },
    {
        "anchor": "A new scattering mechanism of acoustic phonons in relaxor\n  ferroelectrics: the case of KTa_{1-x}Nb_xO_3: The complex interaction between transverse acoustic (TA) phonon, transverse\noptic (TO) phonon and polar nano-domains (PND) in the relaxor ferroelectric\nKTa1-xNbxO3 (KTN) is studied by means of high resolution diffuse and inelastic\nneutron scattering. The experimental results and a comparison with lead\nrelaxors, suggest a new scattering mechanism of the TA phonon by localized\nmodes in PNDs. A theoretical model is developed, which accurately predicts the\nevolution of the TA damping with temperature and wavevector. Such a mechanism\nsuggests the possible use of high frequency acoustic modes for the study of\nnanocomposite materials.",
        "positive": "Dirac cone shift of a passivated topological Bi2Se3 interface state: Gated terahertz cyclotron resonance measurements on epitaxial Bi2Se3 thin\nfilms capped with In2Se3 enable the first spectroscopic characterization of a\nsingle topological interface state from the vicinity of the Dirac point to\nabove the conduction band edge. A precipitous drop in the scattering rate with\nFermi energy is observed that is interpreted as the surface state decoupling\nfrom bulk states and evidence of a shift of the Dirac point towards mid-gap.\nNear the Dirac point, potential fluctuations of 50 meV are deduced from an\nobserved loss of differential optical spectral weight near the Dirac point.\nPotential fluctuations are reduced by a factor of two at higher surface Fermi\nlevels in the vicinity of the conduction band edge inferred from the width of\nthe scattering rate step. The passivated topological interface state attains a\nhigh mobility of 3500 cm2/Vsec near the Dirac point."
    },
    {
        "anchor": "Interactions and Interference in Quantum Dots: Kinks in Coulomb Blockade\n  Peak Positions: We investigate the spin of the ground state of a geometrically confined\nmany-electron system. For atoms, shell structure simplifies this problem-- the\nspin is prescribed by the well-known Hund's rule. In contrast, quantum dots\nprovide a controllable setting for studying the interplay of quantum\ninterference and electron-electron interactions in general cases. In a generic\nconfining potential, the shell-structure argument suggests a singlet ground\nstate for an even number of electrons. The interaction among the electrons\nproduces, however, accidental occurrences of spin-triplet ground states, even\nfor weak interaction, a limit which we analyze explicitly. Variaton of an\nexternal parameter causes sudden switching between these states and hence a\nkink in the conductance. Experimental study of these kinks would yield the\nexchange energy for the ``chaotic electron gas''.",
        "positive": "Datta-Das transistor with enhanced spin control: We consider a two-channel spin transistor with weak spin-orbit induced\ninterband coupling. We show that the coherent transfer of carriers between the\ncoupled channels gives rise to an \\textit{additional} spin rotation. We\ncalculate the corresponding spin-resolved current in a Datta-Das geometry and\nshow that a weak interband mixing leads to enhanced spin control."
    },
    {
        "anchor": "The Density Matrix Renormalization Group for finite Fermi systems: The Density Matrix Renormalization Group (DMRG) was introduced by Steven\nWhite in 1992 as a method for accurately describing the properties of\none-dimensional quantum lattices. The method, as originally introduced, was\nbased on the iterative inclusion of sites on a real-space lattice. Based on its\nenormous success in that domain, it was subsequently proposed that the DMRG\ncould be modified for use on finite Fermi systems, through the replacement of\nreal-space lattice sites by an appropriately ordered set of single-particle\nlevels. Since then, there has been an enormous amount of work on the subject,\nranging from efforts to clarify the optimal means of implementing the algorithm\nto extensive applications in a variety of fields. In this article, we review\nthese recent developments. Following a description of the real-space DMRG\nmethod, we discuss the key steps that were undertaken to modify it for use on\nfinite Fermi systems and then describe its applications to Quantum Chemistry,\nultrasmall superconducting grains, finite nuclei and two-dimensional electron\nsystems. We also describe a recent development which permits symmetries to be\ntaken into account consistently throughout the DMRG algorithm. We close with an\noutlook for future applications of the method.",
        "positive": "Weak Charge Quantization on Superconducting Islands: We consider the Coulomb blockade on a superconductive quantum dot strongly\ncoupled to a lead through a tunnelling barrier and/or normal diffusive metal.\nAndreev transport of the correlated pairs leads to quantum fluctuations of the\ncharge on the dot. These fluctuations result in exponential renormalization of\nthe effective charging energy. We employ two complimentary ways to approach the\nproblem, leading to the coinciding results: the instanton and the functional RG\ntreatment of the non-linear sigma model. We also derive the charging energy\nrenormalization in terms of arbitrary transmission matrix of the multi-channel\ninterface."
    },
    {
        "anchor": "New mechanism for non-trivial intra-molecular vibrational dynamics: We investigate the time evolution process of one selected (initially prepared\nby optical pumping) vibrational molecular state, coupled to all other\nintra-molecular vibrational states of the same molecule, and also to its\nenvironment. Molecular states forming the first reservoir are characterised by\na discrete dense spectrum, whereas the environment reservoir states form a\ncontinuous spectrum. Assuming the equidistant reservoir states we find the\nexact analytical solution of the quantum dynamic equations. System reservoirs\ncouplings yield to spontaneous decay of the states, whereas system-reservoir\nexchange leads to recurrence cycles and Loschmidt echo and double resonances at\nthe interlevel reservoir transitions. Due to these couplings the system $S$\ntime evolution is not reduced to a simple exponential relaxation. We predict\nvarious regimes of the system dynamics, ranging from exponential decay to\nirregular damped oscillations. Namely, we show that there are four possible\ndynamic regimes of the evolution: (i) - independent of the environment\nexponential decay suppressing backward transitions, (ii) Loschmidt echo regime,\n(iii) - incoherent dynamics with multicomponent Loschmidt echo, when the system\nstate exchanges its energy with many states of the reservoir, (iv) - cycle\nmixing regime, when the long term system dynamics appear to be random. We\nsuggest applications of our results for interpretation of femtosecond vibration\nspectra of large molecules and nano-systems.",
        "positive": "Strong terahertz response in bilayer graphene nanoribbons: We reveal that there exists a class of graphene structures (a sub-class of\nbilayer graphene nanoribbons) which has unusually strong optical response in\nthe terahertz (THz) and far infrared (FIR) regime. The peak conductance of\nterahertz/FIR active bilayer ribbons is around two orders of magnitude higher\nthan the universal conductance of $e^2/4\\hbar$ observed in graphene sheets. The\ncriterion for the terahertz/FIR active sub-class is a bilayer graphene\nnanoribbon with one-dimensional massless Dirac Fermion energy dispersion near\nthe $\\Gamma$ point. Our results overcome a significant obstacle that hinders\npotential application of graphene in electronics and photonics."
    },
    {
        "anchor": "Giant enhancement of the third harmonic in graphene integrated in a\n  layered structure: Graphene was shown to have strongly nonlinear electrodynamic properties. In\nparticular, being irradiated by an electromagnetic wave with the frequency\n$\\omega$, it can efficiently generate higher frequency harmonics. Here we\npredict that in a specially designed structure \"graphene -- dielectric --\nmetal\" the third-harmonic ($3\\omega$) intensity can be increased by more than\ntwo orders of magnitude as compared to an isolated graphene layer.",
        "positive": "Long-term data storage in diamond: The negatively-charged nitrogen-vacancy (NV-) center in diamond is the focus\nof widespread attention for applications ranging from quantum information\nprocessing to nanoscale metrology. Although most work so far has focused on the\nNV- optical and spin properties, control of the charge state promises\ncomplementary opportunities. One intriguing possibility is the long-term\nstorage of information, a notion we hereby introduce using NV rich, type-1b\ndiamond. As a proof of principle, we use multi-color optical microscopy to\nread, write, and reset arbitrary data sets with 2-D binary bit density\ncomparable to present digital-video-disk (DVD) technology. Leveraging on the\nsingular dynamics of NV- ionization, we encode information on different planes\nof the diamond crystal with no cross talk, hence extending the storage capacity\nto three dimensions. Further, we correlate the center's charge state and\nnuclear spin polarization of the nitrogen host, and show that the latter is\nrobust to a cycle of NV- ionization and recharge. In combination with\nsuper-resolution microscopy techniques, these observations provide a route\ntowards sub-diffraction NV charge control, a regime where the storage capacity\ncould exceed present technologies."
    },
    {
        "anchor": "Jain hierarchy for the Fractional Quantum Hall Effect: We propose the effective hierarchical partition function which is able to\ndescribe both the Jain states and the Jain-type hierarchical states. Using this\npartition function (effective Lagrangian) we calculate the charge of the\nquasiparticle excitations. We show that the Jain-type hierarchical states are\nequivalent to the system of anyons in the external magnetic field.",
        "positive": "Semimetal with both Rarita-Schwinger-Weyl and Weyl excitations: A relativistic spinor with spin 3/2 is historically called Rarita-Schwinger\nspinor. The right- and left-handed chiral degrees of freedom for the massless\nRarita-Schwinger spinor are independent and are thought of as the left- and\nright-Weyl fermion with helicity \\pm3/2. We study three orbital spin-1/2 Weyl\nsemimetals in the strong spin-orbital coupling limit with time reversal\nsymmetry breaking. We find that in this limit the systems can be a J_{eff}=1/2\nWeyl semimetal or a J_{eff}=3/2 semimetal, depending on the Fermi level\nposition. The latter near Weyl points includes both degrees of freedom of\nRarita-Schwinger-Weyl and Weyl's. A non-local potential separates the Weyl and\nRarita-Schwinger-Weyl degrees of freedom and a relativistic\nRarita-Schwinger-Weyl semimetal emerges. This recipe can be generalized to\nmulit-Weyl semimetal and Weyl fermions with pairing interaction and obtain high\nmonopole charges.\n  Similarly, a spatial inversion breaking Raita-Schwinger-Weyl semimetal may\nalso emerge."
    },
    {
        "anchor": "Spectral Function for the Anderson Model based on Nonequilibrium\n  Perturbation Theory: The paper has been withdrawn. The revised version is shown as\ncond-mat/0506752 and published in Condensed Matter Physics, vol.10,\nNo.2(50)235-248(2007) (Lviv, Ukraine).",
        "positive": "Fermi arcs and DC transport in nanowires of Dirac and Weyl semimetals: The transport properties and electron states in cylinder nanowires of Dirac\nand Weyl semimetals are studied paying special attention to the structure and\nproperties of the surface Fermi arcs. The latter make the electric charge and\ncurrent density distributions in nanowires strongly nonuniform as the majority\nof the charge density is accumulated at the surface. It is found that a Weyl\nsemimetal wire also supports a magnetization current localized mainly at the\nsurface because of the Fermi arcs contribution. By using the Kubo linear\nresponse approach, the direct current (DC) conductivity is calculated and it is\nfound that its spatial profile is nontrivial. By explicitly separating the\ncontributions of the surface and bulk states, it is shown that when the\nelectric chemical potential and/or the radius of the wire is small, the\nelectron transport is determined primarily by the Fermi arcs and the electrical\nconductivity is much higher at the surface than in the bulk. Due to the rise of\nthe surface-bulk transition rate, the relative contribution of the surface\nstates to the total conductivity gradually diminishes as the chemical potential\nincreases. In addition, the DC conductivity at the surface demonstrates\nnoticeable peaks when the Fermi level crosses energies of the surface states."
    },
    {
        "anchor": "Spin-transfer in bilayer magnetic nanopillars at high fields as a\n  function of free layer thickness: Spin transfer in asymmetric Co/Cu/Co bilayer magnetic nanopillars junctions\nhas been studied at low temperature as a function of free-layer thickness. The\nphase diagram for current-induced magnetic excitations has been determined for\nmagnetic fields up to 7.5 T applied perpendicular to the junction surface and\nfree-layers thicknesses from 2 to 5 nm. The junction magnetoresistance is\nindependent of thickness. The critical current for magnetic excitations\ndecreases linearly with decreasing free-layer thickness, but extrapolates to a\nfinite critical current in the limit of zero thickness. The limiting current is\nin quantitative agreement with that expected due to a spin-pumping contribution\nto the magnetization damping. It may also be indicative of a decrease in the\nspin-transfer torque efficiency in ultrathin magnetic layers.",
        "positive": "Acoustic plasmons in extrinsic free-standing graphene: An acoustic plasmon is predicted to occur, in addition to the conventional\ntwo-dimensional (2D) plasmon, as the collective motion of a system of two types\nof electronic carriers coexisting in the very same 2D band of extrinsic (doped\nor gated) graphene. The origin of this novel mode resides in the strong\nanisotropy that is present in the graphene band structure near the Dirac point.\nThis anisotropy allows for the coexistence of carriers moving with two distinct\nFermi velocities along the Gamma-K direction, which leads to two modes of\ncollective oscillation: one mode in which the two types of electrons oscillate\nin phase with one another [this is the conventional 2D graphene plasmon, which\nat long wavelengths (q->0) has the same dispersion, q^1/2, as the conventional\n2D plasmon of a 2D free electron gas], and the other mode found here\ncorresponding to a low-frequency acoustic oscillation [whose energy exhibits at\nlong wavelengths a linear dependence on the 2D wavenumber q] in which the two\ntypes of electrons oscillate out of phase. If this prediction is confirmed\nexperimentally, it will represent the first realization of acoustic plasmons\noriginated in the collective motion of a system of two types of carriers\ncoexisting within the very same band."
    },
    {
        "anchor": "Quasi Two-dimensional Transfer of Elastic Waves: A theory for multiple scattering of elastic waves is presented in a random\nmedium bounded by two ideal free surfaces, whose horizontal size is infinite\nand whose transverse size is smaller than the mean free path of the waves. This\ngeometry is relevant for seismic wave propagation in the Earth crust. We derive\na time-dependent, quasi-2D radiative transfer equation, that describes the\ncoupling of the eigenmodes of the layer (surface Rayleigh waves, SH waves, and\nLamb waves). Expressions are found that relate the small-scale fluctuations to\nthe life time of the modes and to their coupling rates. We discuss a diffusion\napproximation that simplifies the mathematics of this model significantly, and\nwhich should apply at large lapse times. Finally, coherent backscattering is\nstudied within the quasi-2D radiative transfer equation for different source\nand detection configurations.",
        "positive": "Direct Probing Stacking Order and Electronic Spectrum of Rhombohedral\n  Trilayer Graphene with Scanning Tunneling Microscopy: Recently, the rhombohedral trilayer graphene (r-TLG) has attracted much\nattention because of its low-energy flat bands, which are predicted to result\nin many strongly correlated phenomena. Here, we demonstrate that it is possible\nto probe the stacking order and electronic spectrum of the r-TLG directly with\na scanning tunneling microscopy around a monoatomic step edge of the top\ngraphene layer. The tunneling spectra of the r-TLG exhibit four adjacent peaks,\nwhich are generated by the low-energy flat bands, flanking the charge\nneutrality point. Based on these spectra, the true energy gap and the energy\ngap at the K-point of the r-TLG are determined as about 9 meV and 23 meV,\nrespectively. The observed features are well reproduced by a low-energy\neffective Hamiltonian."
    },
    {
        "anchor": "Symmetry, spin-texture, and tunable quantum geometry in a WTe$_2$\n  monolayer: The spin orientation of electronic wavefunctions in crystals is an internal\ndegree of freedom, typically insensitive to electrical knobs. We argue from a\ngeneral symmetry analysis and a $\\vec k \\cdot \\vec p$ perspective, that\nmonolayer 1T'-WTe$_2$ possesses a gate-activated canted spin texture that\nproduces an electrically tunable bulk band quantum geometry. In particular, we\nfind that due to its out-of-plane asymmetry, an applied out-of-plane electric\nfield breaks inversion symmetry to induce both in-plane and out-of-plane\nelectric dipoles. These in-turn generate spin-orbit coupling to lift the spin\ndegeneracy and enable a bulk band Berry curvature and magnetic moment\ndistribution to develop. Further, due to its low symmetry, Berry curvature and\nmagnetic moment in 1T'-WTe$_2$ possess a dipolar distribution in momentum\nspace, and can lead to unconventional effects such as a current induced\nmagnetization and quantum non-linear anomalous Hall effect. These render\n1T'-WTe$_2$ a rich two-dimensional platform for all-electrical control over\nquantum geometric effects.",
        "positive": "Theory of single and two-qubit operations with donor-bound electron\n  spins in germanium: The possibility of quantum computing with spins in germanium nanoscale\ntransistors has recently attracted interest since it promises highly tuneable\nqubits that have encouraging coherence times. We here present the first\ncomplete theory of the orbital states of Ge donor electrons, and use it to show\nthat Ge could have significant advantages over silicon in the implementation of\na donor-based quantum processor architecture. We show that the stronger\nspin-orbit interaction and the larger electron donor wave functions for Ge\ndonors allow for greater tuning of the single qubit energy than for those in Si\ncrystals, thus enabling a large speedup of selective (local) quantum gates.\nFurther, exchange coupling between neighboring donor qubits is shown to be much\nlarger in Ge than in Si, and we show that this greatly relaxes the precision in\ndonor placement needed for robust two-qubit gates. To do this we compare two\nstatistical distributions for Ge:P and Si:P pair couplings, corresponding to\nrealistic donor implantation misplacement, and find that the spin couplings in\nGe:P have a $33\\%$ chance of being within an order of magnitude of the largest\ncoupling, compared with only $10\\%$ for the Si:P donors. This allows fast,\nparallel and robust architectures for quantum computing with donors in Ge."
    },
    {
        "anchor": "Reply to 'Comment on \"Thermodynamics of quantum crystalline membranes\"': In this note, we reply to the comment made by E.I.Kats and V.V.Lebedev\n[arXiv:1407.4298] on our recent work \"Thermodynamics of quantum crystalline\nmembranes\" [Phys. Rev. B 89, 224307 (2014)]. Kats and Lebedev question the\nvalidity of the calculation presented in our work, in particular on the use of\na Debye momentum as a ultra-violet regulator for the theory. We address and\ncounter argue the criticisms made by Kats and Lebedev to our work.",
        "positive": "Ambipolar Electric Field Effect in Metallic Bi2Se3: Topological insulators (TIs) constitute a new class of materials with unique\nproperties resulting from the relativistic-like character and topological\nprotection of their surface states. Theory predicts these to exhibit a rich\nvariety of physical phenomena such as anomalous magneto-electric coupling and\nMajorana excitations. Although TI surface states have been detected in Bi-based\ncompounds by ARPES and STM techniques, electrical control over their density,\nrequired for most transport experiments, remains a challenge. Existing\nmaterials are heavily doped in the bulk, thus preventing electrical tunability\nof the surface states and their integration into topological quantum electronic\ndevices. Here we show that electronic transport in metallic Bi2Se3 nanoscale\ndevices can be controlled by tuning the surface density via the electric field\neffect. By choosing an appropriate high-k dielectric, we are able to shift the\nFermi energy through the charge neutrality point of the surface states,\nresulting in ambipolar transport characteristics reminiscent of those observed\nin graphene. Combining magnetotransport, field effect, and geometry dependent\nexperiments, we provide transport measurements of the surface state mobility,\nand identify likely scattering mechanisms by measuring its temperature\ndependence."
    },
    {
        "anchor": "Exact formulas of the end-to-end Green's functions in non-Hermitian\n  systems: Green's function in non-Hermitian systems has recently been revealed to be\ncapable of directional amplification in some cases. The exact formulas for\nend-to-end Green's functions are significantly important for studies of both\nnon-Hermitian systems and their applications. In this work, based on the\nWidom's formula, we derive exact formulas for the end-to-end Green's functions\nof single-band systems which depend on the roots of a simple algebraic\nequation. These exact formulas allow direct and accurate comparisons between\ntheoretical results and experimentally measured quantities. In addition, we\nverify the prior established integral formula in the bulk region to agree with\nthe result in our framework. We also find that the speed at which the Green's\nfunctions in the bulk region approach the prior established integral formula is\nnot slower than an exponential decay as the system size increases. The\ncorrespondence between the signal amplification and the non-Hermitian skin\neffect is confirmed.",
        "positive": "Macroscopic transverse drift of long current-induced spin coherence in\n  two-dimensional electron gases: We imaged the transport of current-induced spin coherence in a\ntwo-dimensional electron gas confined in a triple quantum well. Nonlocal Kerr\nrotation measurements, based on the optical resonant amplification of the\nelectrically-induced polarization, revealed a large spatial variation of the\nelectron g factor and the efficient generation of a current controlled\nspin-orbit field in a macroscopic Hall bar device. We observed coherence times\nin the nanoseconds range transported beyond half-millimeter distances in a\ndirection transverse to the applied electric field. The measured long spin\ntransport length can be explained by two material properties: large mean free\npath for charge diffusion in clean systems and enhanced spin-orbit coefficients\nin the triple well."
    },
    {
        "anchor": "Resonant electron-lattice cooling in graphene: Controlling energy flows in solids through switchable electron-lattice\ncooling can grant access to a range of interesting and potentially useful\nenergy transport phenomena. Here we discuss a unique switchable\nelectron-lattice cooling mechanism arising in graphene due to phonon emission\nmediated by resonant scattering on defects in crystal lattice, which displays\ninteresting analogy to the Purcell effect in optics. This mechanism strongly\nenhances the electron-phonon cooling rate, since non-equilibrium carriers in\nthe presence of momentum recoil due to disorder can access a larger phonon\nphase space and emit phonons more effciently. Resonant energy dependence of\nphonon emission translates into gate-tunable cooling rates, exhibiting giant\nenhancement of cooling occurring when the carrier energy is aligned with the\nelectron resonance of the defect.",
        "positive": "Silicon Superconducting Quantum Interference Device: We have studied a Superconducting Quantum Interference SQUID device made from\na single layer thin film of superconducting silicon. The superconducting layer\nis obtained by heavily doping a silicon wafer with boron atoms using the Gas\nImmersion Laser Doping (GILD) technique. The SQUID device is composed of two\nnano-bridges (Dayem bridges) in a loop and shows magnetic flux modulation at\nlow temperature and low magnetic field. The overall behavior shows very good\nagreement with numerical simulations based on the Ginzburg-Landau equations."
    },
    {
        "anchor": "Symmetry and spin dephasing in (110)-grown quantum wells: Symmetry and spin dephasing of in (110)-grown GaAs quantum wells (QWs) are\ninvestigated applying magnetic field induced photogalvanic effect (MPGE) and\ntime-resolved Kerr rotation. We show that MPGE provides a tool to probe the\nsymmetry of (110)-grown quantum wells. The photocurrent is only observed for\nasymmetric structures but vanishes for symmetric QWs. Applying Kerr rotation we\nprove that in the latter case the spin relaxation time is maximal, therefore\nthese structures set upper limit of spin dephasing in GaAs QWs. We also\ndemonstrate that structure inversion asymmetry can be controllably tuned to\nzero by variation of delta-doping layer position.",
        "positive": "Ab-initio Theory of Fourier-transformed Quasiparticle Interference Maps\n  and Application to the Topological Insulator Bi$_2$Te$_3$: The quasiparticle interference (QPI) technique is a powerful tool that allows\nto uncover the structure and properties of electronic structure of a material\ncombined with scattering properties of defects at surfaces. Recently this\ntechnique has been pivotal in proving the unique properties of the surface\nstate of topological insulators which manifests itself in the absence of\nbackscattering. In this work we derive a Green function based formalism for the\nab initio computation of Fourier-transformed QPI images. We show the efficiency\nof our new implementation at the examples of QPI that forms around magnetic and\nnon-magnetic defects at the Bi$_2$Te$_3$ surface. This method allows a deepened\nunderstanding of the scattering properties of topologically protected electrons\noff defects and can be a useful tool in the study of quantum materials in the\nfuture."
    },
    {
        "anchor": "Thermally-induced crossover from 2D to 1D behavior in an array of atomic\n  wires: silicon dangling-bond solitons in Si(553)-Au: The self-assembly of submonolayer amounts of Au on the densely stepped\nSi(553) surface creates an array of closely spaced \\atomic wires\" separated by\n1.5 nm. At low temperature, charge transfer between the terraces and the row of\nsilicon dangling bonds at the step edges leads to a charge-ordered state within\nthe row of dangling bonds with x3 periodicity. Interactions between the\ndangling bonds lead to their ordering into a fully two-dimensional (2D) array\nwith centered registry between adjacent steps. We show that as the temperature\nis raised, soliton defects are created within each step edge. The concentration\nof solitons rises with increasing temperature and eventually destroys the 2D\norder by decoupling the step edges, reducing the effective dimensionality of\nthe system to 1D. This crossover from higher to lower dimensionality is\nunexpected and, indeed, opposite to the behavior in other systems.",
        "positive": "Geometry effects in the magnetoconductance of normal and Andreev Sinai\n  billiards: We study the transport properties of low-energy (quasi)particles\nballistically traversing normal and Andreev two-dimensional open cavities with\na Sinai-billiard shape. We consider four different geometrical setups and focus\non the dependence of transport on the strength of an applied magnetic field. By\nsolving the classical equations of motion for each setup we calculate the\nmagnetoconductance in terms of transmission and reflection coefficients for\nboth the normal and Andreev versions of the billiard, calculating in the latter\nthe critical field value above which the outgoing current of holes becomes\nzero."
    },
    {
        "anchor": "NV-center imaging of bubble domains in a 6 \u00c5 film of cobalt with\n  perpendicular magnetization: We employ a scanning NV-center microscope to perform stray field imaging of\nbubble magnetic domains in a perpendicularly magnetized Pt/Co/AlOx trilayer\nwith 6 {\\AA} of Co. The stray field created by the domain walls is\nquantitatively mapped with few-nanometer spatial resolution, with a\nprobe-sample distance of about 100 nm. As an example of application, we show\nthat it should be possible to determine the Bloch or N\\'eel nature of the\ndomain walls, which is of crucial importance to the understanding of\ncurrent-controlled domain wall motion.",
        "positive": "Topological electric current from time-dependent elastic deformations in\n  graphene: We show the possibility of inducing an edge charge current by applying\ntime-dependent strain in gapped graphene samples preserving time reversal\nsymmetry. We demonstrate that this edge current has the same origin as the\nvalley Hall response known to exist in the system."
    },
    {
        "anchor": "Two-dimensional surface charge transport in topological insulators: We construct a theory of charge transport by the surface states of\ntopological insulators in three dimensions. The focus is on the experimentally\nrelevant case when the electron doping is such that the Fermi energy\n$\\epsilon_F$ and transport scattering time $\\tau$ satisfy $\\epsilon_F\n\\tau/\\hbar \\gg 1$, but sufficiently low that $\\epsilon_F$ lies below the bottom\nof the conduction band. Our theory is based on the spin density matrix and\ntakes the quantum Liouville equation as its starting point. The scattering term\nis determined accurately to linear order in the impurity density. We consider\nscattering by charged impurities and short-range scatterers such as surface\nroughness. We calculate also the polarization function in topological\ninsulators, emphasizing the differences from graphene. We find that the main\ncontribution to the conductivity is $\\propto n_i^{-1}$, where $n_i$ is the\nimpurity density, and will have different carrier density dependencies for\ndifferent forms of scattering. Two different contributions to this conductivity\nare traced to the scalar and spin-dependent terms in the Hamiltonian and their\nrelative weight depends on the doping density. Our results contain all\ncontributions to the conductivity to orders zero and one in the impurity\ndensity. We discuss also a way to determine the dominant scattering angles by\nstudying the ratio of the transport relaxation time to the Bloch lifetime as a\nfunction of the Wigner-Seitz radius $r_s$. We also discuss the effect on the\nsurface states of adding metallic contacts.",
        "positive": "Magnetotransport and lateral confinement in an InSe van der Waals\n  Heterostructure: In the last six years, Indium selenide (InSe) has appeared as a new van der\nWaals heterostructure platform which has been extensively studied due to its\nunique electronic and optical properties. Such as transition metal\ndichalcogenides (TMDCs), the considerable bandgap and high electron mobility\ncan provide a potential optoelectronic application. Here we present\nlow-temperature transport measurements on a few-layer InSe van der Waals\nheterostructure with graphene-gated contacts. For high magnetic fields, we\nobserve magnetoresistance minima at even filling factors related to two-fold\nspin degeneracy. By electrostatic gating with negatively biased split gates, a\none-dimensional channel is realized. Close to pinch-off, transport through the\nconstriction is dominated by localized states with charging energies ranging\nfrom 2 to 5 meV. This work opens new possibility to explore the low-dimensional\nphysics including quantum point contact and quantum dot."
    },
    {
        "anchor": "Half Quantum Mirror Hall Effect: We report the discovery of the half-quantized mirror Hall effect, a novel\nquantum-anomaly induced by mirror symmetry in a strong topological insulator\n(TI) film. These films are known to host a pair of gapless Dirac cones\nassociated with surface electrons. Our findings reveal that mirror symmetry\nassigns a unique mirror parity to each Dirac cone, resulting in a\nhalf-quantized Hall conductance of $\\pm\\frac{e^{2}}{2h}$ for each cone. Despite\nthe total electric Hall conductance being null due to time-reversal invariance,\nthe difference in the Hall conductance between the two cones yields a quantized\nHall conductance of $\\frac{e^{2}}{h}$ for the difference in mirror currents.\nThe effect of helical edge mirror current, a crucial feature of this quantum\neffect, can be determined by means of electrical measurements. Overall, the\nhalf-quantum mirror Hall effect reveals a new type of mirror-symmetry induced\nquantum anomaly in a time-reversal invariant lattice system, giving rise to a\ntopological metallic state of matter with time-reversal invariance.",
        "positive": "Adiabatic state preparation of interacting two-level systems: We consider performing adiabatic rapid passage (ARP) using frequency-swept\ndriving pulses to excite a collection of interacting two-level systems. Such a\nmodel arises in a wide range of many-body quantum systems, such as cavity QED\nor quantum dots, where a nonlinear component couples to light. We analyze the\none-dimensional case using the Jordan-Wigner transformation, as well as the\nmean field limit where the system is described by a Lipkin-Meshkov-Glick\nHamiltonian. These limits provide complementary insights into the behavior of\nmany-body systems under ARP, suggesting our results are generally applicable.\nWe demonstrate that ARP can be used for state preparation in the presence of\ninteractions, and identify the dependence of the required pulse shapes on the\ninteraction strength. In general interactions increase the pulse bandwidth\nrequired for successful state transfer, introducing new restrictions on the\npulse forms required."
    },
    {
        "anchor": "Magnetization oscillations and waves driven by pure spin currents: Recent advances in the studies of pure spin currents - flows of angular\nmomentum (spin) not accompanied by the electric currents - have opened new\nhorizons for the emerging technologies based on the electron's spin degree of\nfreedom, such as spintronics and magnonics. The main advantage of pure spin\ncurrent, as compared to the spin-polarized electric current, is the possibility\nto exert spin transfer torque on the magnetization in thin magnetic films\nwithout electrical current flow through the material. In addition to minimizing\nJoule heating and electromigration effects, this characteristic enables the\nimplementation of spin torque devices based on the low-loss insulating magnetic\nmaterials, and offers an unprecedented geometric flexibility. Here we review\nthe recent experimental achievements in investigations of magnetization\noscillations excited by pure spin currents in different magnetic nanosystems\nbased on metallic and insulating magnetic materials. We discuss the spectral\nproperties of spin-current nano-oscillators, and relate them to the spatial\ncharacteristics of the excited dynamic magnetic modes determined by the\nspatially-resolved measurements. We also show that these systems support\nlocking of the oscillations to external microwave signals, as well as their\nmutual synchronization, and can be used as efficient nanoscale sources of\npropagating spin waves.",
        "positive": "Reconfigurable p-n Junction Diodes and the Photovoltaic Effect in\n  Exfoliated MoS2 Films: Realizing basic semiconductor devices such as p-n junctions are necessary for\ndeveloping thin-film and optoelectronic technologies in emerging planar\nmaterials such as MoS2. In this work, electrostatic doping by buried gates is\nused to study the electronic and optoelectronic properties of p-n junctions in\nexfoliated MoS2 flakes. Creating a controllable doping gradient across the\ndevice leads to the observation of the photovoltaic effect in monolayer and\nbilayer MoS2 flakes. For thicker flakes, strong ambipolar conduction enables\nrealization of fully reconfigurable p-n junction diodes with rectifying\ncurrent-voltage characteristics, and diode ideality factors as low as 1.6. The\nspectral response of the photovoltaic effect shows signatures of the predicted\nband gap transitions. For the first excitonic transition, a shift of >4kBT is\nobserved between monolayer and bulk devices, indicating a thickness-dependence\nof the excitonic coulomb interaction."
    },
    {
        "anchor": "Influence of interface transmissivity and inelastic scattering on the\n  electronic entropy and specific heat of diffusive SNS Josephson junctions: We study theoretically the electronic entropy and specific heat in diffusive\nsuperconductor-normal metal-superconductor (SNS) Josephson junctions. In\nparticular, we consider the influence of non-idealities occurring in an actual\nexperiment, such as the presence of barriers at the NS interfaces, the\nspin-flip and inelastic scattering in the N region and quasiparticle subgap\nstates in the superconductors. We find that spin-flip and inelastic scattering\ndo not have, for typical parameters values, a large effect. On the contrary,\nthe presence of barriers suppresses the superconducting correlations in the N\nregion, with the consequence that the entropy and the specific heat get reduced\neventually to those in the absence of superconductivity for opaque interfaces.\nFinally we suggest an experiment and check that it is possible, under realistic\nconditions, to measure the dependence of electronic specific heat on the phase\ndifference between the superconductors.",
        "positive": "Edge spin accumulation in 2D electron and hole systems in a\n  quasi-ballistic regime: We consider a two-dimensional structure with spin-orbit-related splitting of\nthe electron (hole) spectrum and calculate the edge spin density which appears\ndue to the intrinsic mechanism of spin-orbit interaction in the presence of a\ncharge current through the structure. We concentrate on the quasi-ballistic\ncase when a mean free path, being much smaller than the sample size, is larger\nthan the spin precession length determined by the value of the spin-orbit\nsplitting. We show that regardless of the presence or absence of the bulk spin\ncurrent the main source of the edge spin density is the boundary scattering\nitself. The character of the edge spin density depends on the smoothness of the\nbulk impurity potential. We have calculated the edge spin density profile for\nan arbitrary smoothness of the scattering potential in the bulk, and discussed\nrelation to the existing experiments for two-dimensional holes."
    },
    {
        "anchor": "Probing Majorana and Andreev Bound States with Waiting Times: We consider a biased Normal-Superconducting junction with various types of\nsuperconductivity. Depending on the class of superconductivity, a Majorana\nbound state may appear at the interface. We show that this has important\nconsequences on the distribution of waiting times of electrons flowing out of\nsuch an interface. Therefore, the waiting time distribution is shown to be a\nclear fingerprint of Majorana bound state physics and may be considered as an\nexperimental signature of its presence.",
        "positive": "Missing derivative discontinuity of the exchange-correlation energy for\n  attractive interactions: the charge Kondo effect: We show that the energy functional of ensemble Density Functional Theory\n(DFT) [Perdew et al., Phys. Rev. Lett. 49, 1691 (1982)] in systems with\nattractive interactions is a convex function of the fractional particle number\nN and is given by a series of straight lines joining a subset of ground-state\nenergies. As a consequence the exchange-correlation (XC) potential is not\ndiscontinuous for all N. We highlight the importance of this exact result in\nthe ensemble-DFT description of the negative-U Anderson model. In the atomic\nlimit the discontinuity of the XC potential is missing for odd N while for\nfinite hybridizations the discontinuity at even N is broadened. We demonstrate\nthat the inclusion of these properties in any approximate XC potential is\ncrucial to reproduce the characteristic signatures of the charge-Kondo effect\nin the conductance and charge susceptibility."
    },
    {
        "anchor": "Long-range spin transfer in triple quantum dots: Tunneling in a quantum coherent structure is not restricted to only nearest\nneighbours. Hopping between distant sites is possible via the virtual\noccupation of otherwise avoided intermediate states. Here we report the\nobservation of long range transitions in the transport through three quantum\ndots coupled in series. A single electron is delocalized between the left and\nright quantum dots while the centre one remains always empty. Superpositions\nare formed and both charge and spin are exchanged between the outermost dots.\nDetection of the process is achieved via the observation of narrow resonances,\ninsensitive to the transport Pauli spin blockade.",
        "positive": "Laser-launched evanescent surface plasmon polariton field utilized as a\n  direct coherent pumping source to generate emitted nonlinear four-wave mixing\n  radiation: We develop a concept of surface plasmon polaritons (SPPs) based four-wave\nmixing (4WM), in which a laser-launched evanescent SPP field is utilized as a\ncoherent pumping source to involve directly in a nonlinear 4WM process at the\ndielectric/metal interface. Conversion efficiency of the resulting 4WM\nradiation is expected to be dramatically increased due to the local-field\nenhancement effect. Feasibility of implementing this concept at the air/gold\nfilm and graphene flake/gold film interfaces is further examined by numerical\nsimulations. The concept shows intriguing promise for applications in newly\nemerging nanophotonics, optoelectronics, and active plasmonics."
    },
    {
        "anchor": "Classical and quantum magnetisation reversal studied in single\n  nanometer-sized particles and clusters using micro-SQUIDs: Recent progress in experiment on quantum tunnelling of the magnetic moment in\nmesoscopic systems will be reviewed. The emphasis will be made on measurements\nof individual nanoparticles. These nanomagnets allow one to test the border\nbetween classical and quantum behaviour. Using the micro-SQUID magnetometer,\nwaiting time, switching field and telegraph noise measurements show\nunambiguously that the magnetisation reversal of small enough single\ncrystalline nanoparticles is described by a model of thermal activation over a\nsingle-energy barrier. Results on insulating BaFeO nanoparticles show strong\ndeviations from this model below 0.4 K which agree with the theory of\nmacroscopic quantum tunnelling in the low dissipation regime.",
        "positive": "Long-Range Spatial Correlations of Eigenfunctions in Quantum Disordered\n  Systems: This paper is devoted to the statistics of the quantum eigenfunctions in an\nensemble of finite disordered systems (metallic grains). We focus on moments of\ninverse participation ratio. In the universal random matrix limit that\ncorresponds to the infinite conductance of the grains, these moments are\nself-averaging quantities. At large but finite conductance the moments do\nfluctuate due to the long range correlations in the eigenfunctions. We evaluate\nthe distributions of fluctuations at given conductance and geometry of the\ngrains and express them through the spectrum of the diffusion operator in the\ngrain."
    },
    {
        "anchor": "Pseudospin anisotropy of trilayer semiconductor quantum Hall\n  ferromagnets: When two Landau levels are brought to a close coincidence between them and\nwith the chemical potential in the Integer Quantum Hall regime, the two Landau\nlevels can just cross or collapse while the external or pseudospin field that\ninduces the alignment changes. In this work, all possible crossings are\nanalyzed theoretically for the particular case of semiconductor trilayer\nsystems, using a variational Hartree-Fock approximation. The model includes\ntunneling between neighboring layers, bias, intra-layer and inter-layer Coulomb\ninteraction among the electrons. We have found that the general pseudospin\nanisotropy classification scheme used in bilayers applies also to the trilayer\nsituation, with the simple crossing corresponding to an easy-axis ferromagnetic\nanisotropy analogy, and the collapse case corresponding to an easy-plane\nferromagnetic analogy. An isotropic case is also possible, with the levels just\ncrossing or collapsing depending on the filling factor and the quantum numbers\nof the two nearby levels. While our results are valid for any integer filling\nfactor $\\nu$ (=1,2,3,...), we have analyzed in detail the crossings at $\\nu=3$\nand $4$, and we have given clear predictions that will help in their\nexperimental search. In particular, the present calculations suggest that by\nincreasing the bias, the trilayer system at these two filling factors can be\ndriven from an easy-plane anisotropy regime to an easy-axis regime, and then\ncan be driven back to the easy-plane regime. This kind of reentrant behavior is\nan unique feature of the trilayers, compared with the bilayers.",
        "positive": "A fundamental mechanism for carbon-film lubricity identified by means of\n  ab initio molecular dynamics: Different hypotheses have been proposed to explain the mechanism for the\nextremely low friction coefficient of carbon coatings and its undesired\ndependence on air humidity. A decisive atomistic insight is still lacking\nbecause of the difficulties in monitoring what actually happens at the buried\nsliding interface. Here we perform large-scale ab initio molecular dynamics\nsimulations of both undoped and silicon-doped carbon films sliding in the\npresence of water. We observe the tribologically-induced surface hydroxylation\nand subsequent formation of a thin film of water molecules bound to the\nOH-terminated surface by hydrogen bonds. The comparative analysis of\nsilicon-incorporating and clean surfaces, suggests that this two-step process\ncan be the key phenomenon to provide high slipperiness to the carbon coatings.\nThe water layer is, in fact, expected to shelter the carbon surface from direct\nsolid-on-solid contact and make any counter surface slide extremely easily on\nit. The present insight into the wettability of carbon-based films can be\nuseful for designing new coatings for biomedical and energy-saving applications\nwith environmental adaptability."
    },
    {
        "anchor": "Synergistic Photon Management and Strain-Induced Band Gap Engineering of\n  Two-Dimensional MoS2 Using Semimetal Composite Nanostructures: 2D MoS2 attracts increasing attention for its application in flexible\nelectronics and photonic devices. For 2D material optoelectronic devices, light\nabsorption of the molecularly thin 2D absorber would be one of the key limiting\nfactors in device efficiency, and conventional photon management techniques are\nnot necessarily compatible with them. In this paper, we show two semimetal\ncomposite nanostructures for synergistic photon management and strain-induced\nband gap engineering of 2D MoS2: (1) pseudo-periodic Sn nanodots, (2)\nconductive SnOx (x<1) core-shell nanoneedle structures. Without sophisticated\nnanolithography, both nanostructures are self-assembled from physical vapor\ndeposition. 2D MoS2 achieves up to >15x enhancement in absorption at\n{\\lambda}=650-950 nm under Sn nanodots, and 20-30x at {\\lambda}=700-900 nm\nunder SnOx (x<1) nanoneedles, both spanning from visible to near infrared\nregime. Enhanced absorption in MoS2 results from strong near field enhancement\nand reduced MoS2 band gap due to the tensile strain induced by the Sn\nnanostructures, as confirmed by Raman and photoluminescence spectroscopy.\nEspecially, we demonstrate that up to 3.5% biaxial tensile strain is introduced\nto 2D MoS2 using conductive nanoneedle-structured SnOx (x<1), which reduces the\nband gap by ~0.35 eV to further enhance light absorption at longer wavelengths.\nTo the best of our knowledge, this is the first demonstration of a synergistic\ntriple-functional photon management, stressor, and conductive electrode layer\non 2D MoS2. Such synergistic photon management and band gap engineering\napproach for extended spectral response can be further applied to other 2D\nmaterials for future 2D photonic devices.",
        "positive": "Interlayer hybridization in graphene quasicrystal and other bilayer\n  graphene systems: The incommensurate 30$^{\\circ}$ twisted bilayer graphene (BG) possesses both\nrelativistic Dirac fermions and quasiperiodicity with 12-fold rotational\nsymmetry arising from the interlayer interaction\n[\\href{https://science.sciencemag.org/content/361/6404/782}{Ahn et al., Science\n\\textbf{361}, 782 (2018)} and\n\\href{https://www.pnas.org/content/115/27/6928}{Yao et al., Proc. Natl. Acad.\nSci. \\textbf{115}, 6928 (2018)}]. Understanding how the interlayer states\ninteract with each other is of vital importance for identifying and\nsubsequently engineering the quasicrystalline order in the layered structures.\nHerein, via symmetry and group representation theory we unravel the interlayer\nhybridization selection rules governing the interlayer coupling in both\nuntwisted and twisted BG systems. Compared with the only allowed equivalent\nhybridization in $D_{6h}$ untwisted BG, $D_6$ twisted BG permits equivalent and\nmixed hybridizations, and $D_{6d}$ graphene quasicrystal allows both equivalent\nand non-equivalent hybridizations. The energy-dependent hybridization strengths\nin graphene quasicrystal and $D_6$ twisted BG show two remarkable\ncharacteristics: (i) near the Fermi level the weak hybridization owing to the\nrelatively large energy difference between Dirac bands from top and bottom\nlayers, and (ii) in high-energy regions the electron-hole asymmetry of\nhybridization strength with stronger interlayer coupling for holes, which\narises from the non-nearest-neighbor interlayer hoppings and the wave-function\nphase difference between paring states. These hybridization-generated band\nstructures and their hybridization strength characteristics are verified by the\ncalculated optical conductivity spectra. Our theoretical study paves a way for\nrevealing the interlayer hybridization in van der Waals layered systems."
    },
    {
        "anchor": "First-principles method for electron-phonon coupling and electron\n  mobility: Applications to 2D materials: We present density functional theory calculations of the phonon-limited\nmobility in n-type monolayer graphene, silicene and MoS$_2$. The material\nproperties, including the electron-phonon interaction, are calculated from\nfirst-principles. We provide a detailed description of the normalized full-band\nrelaxation time approximation for the linearized Boltzmann transport equation\n(BTE) that includes inelastic scattering processes. The bulk electron-phonon\ncoupling is evaluated by a supercell method. The method employed is fully\nnumerical and does therefore not require a semi-analytic treatment of part of\nthe problem and, importantly, it keeps the anisotropy information stored in the\ncoupling as well as the band structure. In addition, we perform calculations of\nthe low-field mobility and its dependence on carrier density and temperature to\nobtain a better understanding of transport in graphene, silicene and monolayer\nMoS$_2$. Unlike graphene, the carriers in silicene show strong interaction with\nthe out-of-plane modes. We find that graphene has more than an order of\nmagnitude higher mobility compared to silicene. For MoS$_2$, we obtain several\norders of magnitude lower mobilities in agreement with other recent theoretical\nresults. The simulations illustrate the predictive capabilities of the newly\nimplemented BTE solver applied in simulation tools based on first-principles\nand localized basis sets.",
        "positive": "Frequency modulated self-oscillation and phase inertia in a synchronized\n  nanowire mechanical resonator: Synchronization has been reported for a wide range of self-oscillating\nsystems. However, even though it has been predicted theoretically for several\ndecades, the experimental realization of phase self-oscillation, sometimes\ncalled phase trapping, in the high driving regime has been studied only\nrecently. We explored in detail the phase dynamics in a synchronized field\nemission SiC nanoelectromechanical system with intrinsic feedback. A richer\nvariety of phase behavior has been unambiguously identified, implying phase\nmodulation and inertia. This synchronization regime is expected to have\nimplications for the comprehension of the dynamics of interacting\nself-oscillating networks and for the generation of frequency modulated signals\nat the nanoscale"
    },
    {
        "anchor": "Peak-effect and surface crystal-glass transition for surface-pinned\n  vortex array: We present a theoretical and experimental study of the peak effect in the\nsurface pinning of vortices. It is associated with a sharp transition in the\nvortex slippage length which we relate to a crossover from a weakly disordered\ncrystal to a surface glass state. Experiments are performed on ion-beam etched\nNb crystals. The slippage length is deduced from 1kHz-1MHz linear AC\npenetration depth measurements.",
        "positive": "Exact Landau Level Description of Geometry and Interaction in a Flatband: Flatbands appear in many condensed matter systems, such as in high magnetic\nfields, correlated materials and moire heterostructures. They are characterized\nby intrinsic geometric properties such as the Berry curvature and Fubini-Study\nmetric. In general the band geometry is nonuniform in momentum space, making\nits influence on electron-electron interactions a difficult problem to\nunderstand analytically. In this work, we study this problem in a topological\nflatband of Chern number C=1 with the ideal properties that the Berry curvature\nis positive definite and fluctuates in sync with Fubini-Study metric. We derive\nan exact correspondence between such ideal flatbands and Landau levels by\nshowing how the band geometry fluctuation in ideal flatbands gives raise to a\nnew type of interaction in Landau levels which depends on the center-of-mass of\ntwo particles. We characterize such interaction by generalizing the usual\nHaldane pseudopotentials. This mapping gives exact zero-energy ground states\nfor short-ranged repulsive generalized pseudopotentials in flatbands, in\nanalogy to fractional quantum Hall systems. Driving the center-of-mass\ninteractions beyond the repulsive regime leads to a dramatic reconstruction of\nthe ground states towards gapless phases. The generalized pseudopotential could\nbe a useful basis for future numerical studies."
    },
    {
        "anchor": "Dirac electron under periodic magnetic field: Platform for fractional\n  Chern insulator and generalized Wigner crystal: We propose a platform for flat Chern band by subjecting two-dimensional Dirac\nmaterials -- such as graphene and topological insulator thin films -- to a\nperiodic magnetic field, which can be created by the vortex lattice of a\ntype-II superconductor. As a generalization of the $n=0$ Landau level, the flat\nband of Dirac fermion under a nonuniform magnetic field remains at zero energy,\nexactly dispersionless and topologically protected, while its local density of\nstates is spatially modulated due to the magnetic field variation. In the\npresence of short-range repulsion, we find fractional Chern insulators emerge\nat filling factors $\\nu=1/m$, whose ground states are generalized Laughlin\nwavefunctions. We further argue that generalized Wigner crystals may emerge at\ncertain commensurate fillings under a highly nonuniform magnetic field in the\nform of a flux line lattice.",
        "positive": "Phonon-Induced Transparency in Functionalized Single Layer Graphene: Herein, intervalley scattering is exploited to account for anomalous\nantiresonances in the infrared spectra of doped and disordered single layer\ngraphene. We present infrared spectroscopy measurements of graphene grafted\nwith iodophenyl moieties in both reflection microscopy and transmission\nconfigurations. Asymmetric transparency windows at energies corresponding to\nphonon modes near the {\\Gamma} and K points are observed, in contrast to the\nfeatureless spectrum of pristine graphene. These asymmetric antiresonances are\ndemonstrated to vary as a function of the chemical potential. We propose a\nmodel which involves coherent intraband scattering with defects and phonons,\nthus relaxing the optical selection rule forbidding access to ${\\bf q} \\neq$\n{\\Gamma} phonons. This interpretation of the new phenomenon is supported by our\nnumerical simulations that reproduce the experimental features."
    },
    {
        "anchor": "Collective modes in multi-Weyl semimetals: We investigate collective modes in three dimensional (3D) gapless multi-Weyl\nsemimetals with anisotropic energy band dispersions (i.e., $E\\sim \\sqrt{\nk_{\\parallel}^{2J} + k_z^2}$, where $k_{\\parallel}$ and $k_z$ are wave vectors\nand $J$ is a positive integer). For comparison, we also consider the gapless\nsemimetals with the isotropic band dispersions (i.e., $E\\sim k^J$). We\ncalculate analytically long-wavelength plasma frequencies incorporating\ninterband transitions and chiral properties of carriers. For both the isotropic\nand anisotropic cases, we find that interband transitions and chirality lead to\nthe depolarization shift of plasma frequencies. For the isotropic parabolic\nband dispersion (i.e., $N=2$, $E\\sim k^2$), the long-wavelength plasma\nfrequencies lie outside the single particle excitation regions for all carrier\ndensities, and thus the plasmons do not decay via Landau damping. For the\nhigher-order band dispersions ($N \\ge 3$) the long-wavelength plasmons\nexperience damping below a critical density. For systems with the anisotropic\ndispersion the density dependence of the long-wavelength plasma frequency along\nthe direction of non-linear dispersion behaves like that of the isotropic\nlinear band model ($N=1$), while along the direction of linear dispersion it\nbehaves like that of the isotropic non-linear model ($N \\ge 2$). Plasmons along\nboth directions remain undamped over a broad range of densities due to the\nchirality induced depolarization shift. Our results provide a comprehensive\npicture of how band dispersion and chirality affect plasmon behaviors in 3D\ngapless chiral systems with the arbitrary band dispersion.",
        "positive": "Quantum Noise Measurement of a Carbon Nanotube Quantum Dot in the Kondo\n  Regime: The current emission noise of a carbon nanotube quantum dot in the Kondo\nregime is measured at frequencies $\\nu$ of the order or higher than the\nfrequency associated with the Kondo effect $k_B T_K/h$, with $T_K$ the Kondo\ntemperature. The carbon nanotube is coupled via an on-chip resonant circuit to\na quantum noise detector, a superconductor-insulator-superconductor junction.\nWe find for $h \\nu \\approx k_B T_K$ a Kondo effect related singularity at a\nvoltage bias $eV \\approx h \\nu $, and a strong reduction of this singularity\nfor $h \\nu \\approx 3 k_B T_K$, in good agreement with theory. Our experiment\nconstitutes a new original tool for the investigation of the non-equilibrium\ndynamics of many-body phenomena in nanoscale devices."
    },
    {
        "anchor": "Flat bands and multi-state memory devices from chiral domain wall\n  superlattices in magnetic Weyl semimetals: We propose a novel analog memory device utilizing the gigantic magnetic Weyl\nsemimetal (MWSM) domain wall (DW) magnetoresistance. We predict that the\nnucleation of domain walls between contacts will strongly modulate the\nconductance and allow for multiple memory states, which has been long\nsought-after for use in magnetic random access memories or memristive\nneuromorphic computing platforms. We motivate this conductance modulation by\nanalyzing the electronic structure of the helically-magnetized MWSM\nHamiltonian, and report tunable flat bands in the direction of transport in a\nhelically-magnetized region of the sample for Bloch and Neel-type domain walls\nvia the onset of a local axial Landau level spectrum within the bulk of the\nsuperlattice. We show that Bloch devices also provide means for the generation\nof chirality-polarized currents, which provides a path towards nanoelectronic\nutilization of chirality as a new degree of freedom in spintronics.",
        "positive": "Nonlocal Spin Dynamics in the Crossover from Diffusive to Ballistic\n  Transport: Improved fabrication techniques have enabled the possibility of ballistic\ntransport and unprecedented spin manipulation in ultraclean graphene devices.\nSpin transport in graphene is typically probed in a nonlocal spin valve and is\nanalyzed using spin diffusion theory, but this theory is not necessarily\napplicable when charge transport becomes ballistic or when the spin diffusion\nlength is exceptionally long. Here, we study these regimes by performing\nquantum simulations of graphene nonlocal spin valves. We find that conventional\nspin diffusion theory fails to capture the crossover to the ballistic regime as\nwell as the limit of long spin diffusion length. We show that the latter can be\ndescribed by an extension of the current theoretical framework. Finally, by\ncovering the whole range of spin dynamics, our study opens a new perspective to\npredict and scrutinize spin transport in graphene and other two-dimensional\nmaterial-based ultraclean devices."
    },
    {
        "anchor": "Gate-Tunable Optical Extinction of Graphene Nanoribbon Nanoclusters: We investigate the optical response of graphene nanoribbons (GNRs) using the\nbroadband nonlinear generation and detection capabilities of nanoscale\njunctions created at the LaAlO$_3$/SrTiO$_3$ interface. GNR nanoclusters\nmeasured to be as small as 1-2 GNRs in size are deposited on the LaAlO$_3$\nsurface with an atomic force microscope tip. Time-resolved nonlinear optical\nprobes of GNR nanoclusters reveal a strong, gate-tunable second and third\nharmonic response, as well as strong extinction of visible to near-infrared\n(VIS-NIR) light at distinct wavelengths, similar to previous reports with\ngraphene.",
        "positive": "Two dimensional photonic quasicrystal edge states protected by second\n  Chern number: Topological physics in photonic systems have attracted great attentions in\nrecent years. In this work, we theoretically study the one and two dimensional\nphotonic quasicrystal resonator lattices characterized by the first and second\nChern number, which show exotic boundary states within the photonic energy band\ngap. In particular, the second Chern number protected edge states has opened up\nnew possibilities for realizing topological physics of dimensions higher than\nthree in photonic systems, which is highly sought for. Such photonic systems\ncan be easily experimentally realized in regular photonic crystal with\ndielectric rods in air, by varying the radius of the rods, so we propose\nexperiments realizing our predictions."
    },
    {
        "anchor": "Multiple energy-scales in vertex-frustrated mesospin systems: The interplay between topology and energy-hierarchy plays a vital role in the\ncollective magnetic order in artificial ferroic systems. Here we investigate,\nexperimentally, the effect of having one or two activation energies of\ninteracting Ising-like magnetic islands -- mesospins -- in thermalized,\nvertex-frustrated lattices. The thermally arrested magnetic states of the\nelements were determined using synchrotron-based magnetic microscopy after\ncooling the samples from temperatures above the Curie temperature of the\nmaterial. Statistical analysis of the correlations between mesospins across\nseveral length-scales, reveals changes in the magnetic order, reflecting the\namount of ground state plaquettes realized for a vertex-frustrated lattice. We\nshow that the latter depends on the presence, or not, of different activation\nenergies.",
        "positive": "Size induced metal insulator transition in nanostructured Niobium thin\n  films: Intragranular and intergranular contributions: With a reduction in the average grain size in nanostructured films of\nelemental Nb, we observe a systematic crossover from metallic to\nweakly-insulating behavior. An analysis of the temperature dependence of the\nresistivity in the insulating phase clearly indicates the existence of two\ndistinct activation energies corresponding to inter-granular and intra-granular\nmechanisms of transport. While the high temperature behavior is dominated by\ngrain boundary scattering of the conduction electrons, the effect of\ndiscretization of energy levels due to quantum confinement shows up at low\ntemperatures. We show that the energy barrier at the grain boundary is\nproportional to the width of the largely disordered inter-granular region,\nwhich increases with a decrease in the grain size. For a metal-insulator\ntransition to occur in nano-Nb due to the opening up of an energy gap at the\ngrain boundary, the critical grain size is ~ 8nm and the corresponding grain\nboundary width is ~ 1.1nm."
    },
    {
        "anchor": "Chern insulators for electromagnetic waves in electrical circuit\n  networks: Periodic networks composed of capacitors and inductors have been demonstrated\nto possess topological properties with respect to incident electromagnetic\nwaves. Here, we develop an analogy between the mathematical description of\nwaves propagating in such networks and models of Majorana fermions hopping on a\nlattice. Using this analogy we propose simple electrical network architectures\nthat realize Chern insulating phases for electromagnetic waves. Such Chern\ninsulating networks have a bulk gap for a range of signal frequencies that is\neasily tunable and exhibit topologically protected chiral edge modes that\ntraverse the gap and are robust to perturbations. The requisite time reversal\nsymmetry breaking is achieved by including a class of weakly dissipative Hall\nresistor elements whose physical implementation we describe in detail.",
        "positive": "Quantum Hall states for Rydberg atoms with laser-assisted dipole-dipole\n  interactions: Rydberg atoms with dipole-dipole interactions provide intriguing platforms to\nexplore exotic quantum many-body physics. Here we propose a novel scheme with\nlaser-assisted dipole-dipole interactions to realize synthetic magnetic field\nfor Rydberg atoms in a two-dimensional array configuration, which gives rise to\nthe exotic bosonic topological states. In the presence of an external effective\nZeeman splitting gradient, the dipole-dipole interaction between neighboring\nRydberg atoms along the gradient direction is suppressed, but can be assisted\nwhen Raman lights are applied to compensate the energy difference. With this\nscheme we generate a controllable uniform magnetic field for the complex\nspin-exchange coupling model, which can be mapped to hard core bosons coupling\nto an external synthetic magnetic field. The highly tunable flat Chern bands of\nthe hard core bosons are then obtained and moreover, the bosonic fractional\nquantum Hall states can be achieved with experimental feasibility. This work\nopens an avenue for the realization of the highly-sought-after bosonic\ntopological orders using Rydberg atoms."
    },
    {
        "anchor": "Stress-induced traps in multilayered structures: The trap parameters of defects in Si/CaF2 multilayered structures were\ndetermined from the analysis of optical charging spectroscopy measurements. Two\nkinds of maxima were observed. Some of them were rather broad, corresponding to\n\"normal\" traps, while the others, very sharp, were attributed to stress-induced\ntraps. A procedure of optimal linear smoothing the noisy experimental data has\nbeen developed and applied. This procedure is based on finding the minimal\nvalue of the relative error with respect to the value of the smoothing window.\nIn order to obtain a better accuracy for the description of the\ntrapping-detrapping process, a Gaussian temperature dependence of the capture\ncrosssections characterizing the stress-induced traps was introduced. Both the\nnormal and the stress-induced traps have been characterized, including some\npreviously considered as only noise features.",
        "positive": "Numerical study of charge and statistics of Laughlin quasi-particles: We present numerical calculations of the charge and statistics, as extracted\nfrom Berry phases, of the Laughlin quasi-particles, near filling fraction 1/3,\nand for system sizes of up to 200 electrons. For the quasi-holes our results\nconfirm that the charge and statistics parameter are $e/3$ and 1/3,\nrespectively. For the quasi-electron charge we find a slow convergence towards\nthe expected value of $-e/3$, with a finite size correction for $N$ electrons\nof approximately $-0.13e/N$. The statistics parameter for the quasi-electrons\nhas no well defined value even for 200 electrons, but might possibly converge\nto 1/3. Most noteworthy, it takes on the same sign as for the quasi-holes, due\nto terms that have previously been ignored. The anyon model works well for the\nquasi-holes, but requires singular two-anyon wave functions for modelling two\nLaughlin quasi-electrons."
    },
    {
        "anchor": "Aharonov-Bohm oscillations of a particle coupled to dissipative\n  environments: The amplitude of the Bohm-Aharonov oscillations of a particle moving around a\nring threaded by a magnetic flux and coupled to different dissipative\nenvironments is studied. The decay of the oscillations when increasing the\nradius of the ring is shown to depend on the spatial features of the coupling.\nWhen the environment is modelled by the Caldeira-Leggett bath of oscillators,\nor the particle is coupled by the Coulomb potential to a dirty electron gas,\ninterference effects are suppressed beyond a finite length, even at zero\ntemperature. A finite renormalization of the Aharonov-Bohm oscillations is\nfound for other models of the environment.",
        "positive": "Optical properties of orthorhombic germanium sulfide: Unveiling the\n  Anisotropic Nature of Wannier Exciton: To fully explore exciton-based applications and improve their performance, it\nis essential to understand the exciton behavior in anisotropic materials. Here,\nwe investigate the optical properties of anisotropic excitons in GeS\nencapsulated by h-BN, using different approaches that combine polarization- and\ntemperature-dependent photoluminescence (PL) measurements, \\textit{ab initio}\ncalculations, and effective mass approximation (EMA). Using the Bethe-Salpeter\nEquation (BSE) method, we found that the optical absorption spectra in GeS are\nsignificantly affected by the Coulomb interaction included in the BSE method,\nwhich shows the importance of excitonic effects besides it exhibits a\nsignificant dependence on the direction of polarization, revealing the\nanisotropic nature of bulk GeS. Combining \\textit{ab initio} calculations and\nEMA methods, we investigate the quasi-hydrogenic exciton states and oscillator\nstrength (OS) of GeS along the zigzag and armchair axes. We found that the\nanisotropy induces lifting of the degeneracy and mixing of the excitonic states\nin GeS, which results in highly nonhydrogenic features. Very good agreement\nwith the experiment is observed."
    },
    {
        "anchor": "Quantum transport properties of two-dimensional electron gases under\n  high magnetic fields: We study quantum transport properties of two-dimensional electron gases under\nhigh perpendicular magnetic fields. For this purpose, we reformulate the\nhigh-field expansion, usually done in the operatorial language of the\nguiding-center coordinates, in terms of vortex states within the framework of\nreal-time Green functions. These vortex states arise naturally from the\nconsideration that the Landau levels quantization can follow directly from the\nexistence of a topological winding number. The microscopic computation of the\ncurrent can then be performed within the Keldysh formalism in a systematic way\nat finite magnetic fields $B$ (i.e. beyond the semi-classical limit $B =\n\\infty$). The formalism allows us to define a general vortex current density as\nlong as the gradient expansion theory is applicable. As a result, the total\ncurrent is expressed in terms of edge contributions only. We obtain the first\nand third lowest order contributions to the current due to Landau-levels mixing\nprocesses, and derive in a transparent way the quantization of the Hall\nconductance. Finally, we point out qualitatively the importance of\ninhomogeneities of the vortex density to capture the dissipative longitudinal\ntransport.",
        "positive": "The 2D percolation transition at finite temperature: The phase boundary\n  for in-plane ferromagnetism in $\\approx$2 ML Fe/W(110) films: A two dimensional (2D) percolation transition in Fe/W(110) ultrathin magnetic\nfilms occurs when islands in the second atomic layer percolate and resolve a\nfrustrated magnetic state to produce long-range in-plane ferromagnetic order.\nNovel measurements of the magnetic susceptibility $\\chi(\\theta)$ as the films\nare deposited at a constant temperature, allow the long-range percolation\ntransition to be observed as a sharp peak consistent with a critical phase\ntransition. The measurements are used to trace the\nparamagnetic-to-ferromagnetic phase boundary between the $T=0$ percolation\nmagnetic transition and the thermal Curie magnetic transition of the undiluted\nfilm. A quantitative comparison to critical scaling theory is made by fitting\nthe functional form of the phase boundary. The fitted parameters are then used\nin theoretical expressions for $\\chi(T)$ in the critical region of the\nparamagnetic state to provide an excellent, independent representation of the\nexperimental measurements."
    },
    {
        "anchor": "First-principles calculations of Cu(001) thin films: quantum size effect\n  in surface energetics and surface chemical reactivities: First-principles calculations of Cu(001) free-standing thin films have been\nperformed to investigate the oscillatory quantum size effects exhibited in\nsurface energy, work function, atomic relaxation, and adsorption energy of the\ncesium adsorbate. The quantum well states have been shown and clarified at\nparticular $k$-points corresponding to the stationary extrema in bulk Brillouin\nzone, which are in good agreement with experimental observations. The\ncalculated surface energetics and geometry relaxations are clearly featured by\nquantum oscillations as a function of the film thickness of the film with\noscillation periods characterized by a superposition of long and short length\nscales. Furthermore, we have investigated Cs adsorption onto Cu(001) thin films\nas a function of the film thickness. Our systematic calculated results clearly\nshow the large-amplitude quantum oscillations in adsorption energetics, which\nmay be used to tailor catalysis, chemical reactions and other surface processes\nin nanostructured materials.",
        "positive": "Topological quantization of the spin Hall effect in two-dimensional\n  paramagnetic semiconductors: We propose models of two dimensional paramagnetic semiconductors where the\nintrinsic spin Hall effect is exactly quantized in integer units of a\ntopological charge. The model describes a topological insulator in the bulk,\nand a \"holographic metal\" at the edge, where the number of extended edge states\ncrossing the Fermi level is dictated by (exactly equal to) the bulk topological\ncharge. We also demonstrate the spin Hall effect explicitly in terms of the\nspin accumulation caused by the adiabatic flux insertion."
    },
    {
        "anchor": "Kramers' degeneracy for open systems in thermal equilibrium: Kramers' degeneracy theorem underpins many interesting effects in quantum\nsystems with time-reversal symmetry. We show that the generator of dynamics for\nMarkovian open fermionic systems can exhibit an analogous degeneracy, protected\nby a combination of time-reversal symmetry and the microreversibility (detailed\nbalance) property of systems at thermal equilibrium -- the degeneracy is lifted\nif either condition is not met. We provide simple examples of this phenomenon\nand show that the degeneracy is reflected in the single-particle Green's\nfunctions. Furthermore, we show that certain experimental signatures of\ntopological edge modes in open many-body systems can be protected by\nmicroreversibility in the same way. Our results highlight the importance of\ndetailed balance in characterizing open topological matter.",
        "positive": "Yu-Shiba-Rusinov states in the charge-density modulated superconductor\n  NbSe2: NbSe$_2$ is a remarkable superconductor in which charge-density order\ncoexists with pairing correlations at low temperatures. Here, we study the\ninterplay of magnetic adatoms and their Yu-Shiba-Rusinov (YSR) bound states\nwith the charge density order. Exploiting the incommensurate nature of the\ncharge-density wave (CDW), our measurements provide a thorough picture of how\nthe CDW affects both the energies and the wavefunctions of the YSR states. Key\nfeatures of the dependence of the YSR states on adsorption site relative to the\nCDW are explained by model calculations. Several properties make NbSe$_2$ a\npromising substrate for realizing topological nanostructures. Our results will\nbe important in designing such systems."
    },
    {
        "anchor": "Quantum dynamics of a driven three-level Josephson-atom maser: Recently, a lasing effect has been observed in a superconducting nano-circuit\nwhere a Cooper pair box, acting as an artificial three-level atom, was coupled\nto a resonator. Motivated by this experiment, we analyze the quantum dynamics\nof a three-level atom coupled to a quantum-mechanical resonator in the presence\nof a driving on the cavity within the framework of the Lindblad master\nequation. As a result, we have access to the dynamics of the atomic level\npopulations and the photon number in the cavity as well as to the output\nspectrum. The results of our quantum approach agree with the experimental\nfindings. The presence of a fluctuator in the circuit is also analyzed.\nFinally, we compare our results with those obtained within a semiclassical\napproximation.",
        "positive": "Strongly anisotropic RKKY interaction in monolayer black phosphorus: We theoretically study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction\nin two-dimensional black phosphorus, phosphorene. The RKKY interaction enhances\nsignificantly for the low levels of hole doping owing to the nearly valence\nflat band. Remarkably, for the hole-doped phosphorene, the highest RKKY\ninteraction occurs when two impurities are located along the zigzag direction\nand it tends to a minimum value with changing the direction from the zigzag to\nthe armchair direction. We show that the interaction is highly anisotropic and\nthe magnetic ground-state of two magnetic adatoms can be tuned by changing the\nrotational configuration of impurities. Owing to the anisotropic band\ndispersion, the oscillatory behavior with respect to the angle of the rotation\nis well-described by $\\sin(2k_{\\rm F}R)$, where the Fermi wavelength $k_{\\rm\nF}$ changes in different directions. We also find that the tail of the RKKY\noscillations falls off as $1/R^2$ at large distances."
    },
    {
        "anchor": "Superconducting Spin Qubits: We propose and theoretically investigate spin superconducting qubits. Spin\nsuperconducting qubit consists of a single spin confined in a Josephson\njunction. We show that owing to spin-orbit interaction, superconducting\ndifference across the junction can polarize this spin. We demonstrate that this\nenables single qubit operations and more complicated quantum gates, where spins\nof different qubits interact via a mutual inductance of superconducting loop\nwhere the junctions are embedded. Recent experimental realizations of Josephson\njunctions made of semiconductor quantum dots in contact with superconducting\nleads have shown that the number of electrons in the quantum dot can be tuned\nby a gate voltage. Spin superconducting qubit is realized when the number of\nelectrons is odd. We discuss the qubit properties at phenomenological level. We\npresent a microscopic theory that enables us to make accurate estimations of\nthe qubit parameters by evaluating the spin-dependent Josephson energy in the\nframework of fourth-order perturbation theory.",
        "positive": "Topological quantum states of matter in iron-based superconductors: From\n  concepts to material realization: We review recent progress in the explorations of topological quantum states\nof matter in iron-based superconductors. In particular, we focus on the\nnontrivial topology existing in the band structures and superconducting states\nof iron's 3d orbitals. The basic concepts, models, materials and experimental\nresults are reviewed. The natural integration between topology and\nhigh-temperature superconductivity in iron-based superconductors provides great\nopportunities to study topological superconductivity and Majorana modes at high\ntemperature."
    },
    {
        "anchor": "Quantum simulator to emulate lower dimensional molecular structure: Bottom-up quantum simulators have been developed to quantify the role of\nvarious interactions, dimensionality, and structure in creating electronic\nstates of matter. Here, we demonstrated a solid-state quantum simulator\nemulating molecular orbitals, based solely on positioning individual cesium\natoms on an indium antimonide surface. Using scanning tunneling microscopy and\nspectroscopy, combined with ab initio calculations, we showed that artificial\natoms could be made from localized states created from patterned cesium rings.\nThese artificial atoms served as building blocks to realize artificial\nmolecular structures with different orbital symmetries. These corresponding\nmolecular orbitals allowed us to simulate 2D structures reminiscent of well\nknown organic molecules. This platform could further be used to monitor the\ninterplay between atomic structures and the resulting molecular orbital\nlandscape with sub-molecular precision.",
        "positive": "MoS2 Nanoribbon Transistors: Transition from Depletion-mode to\n  Enhancement-mode by Channel Width Trimming: We study the channel width scaling of back-gated MoS2\nmetal-oxide-semiconductor field-effect transistors (MOSFETs) from 2 {\\mu}m down\nto 60 nm. We reveal that the channel conductance scales linearly with channel\nwidth, indicating no evident edge damage for MoS2 nanoribbons with widths down\nto 60 nm as defined by plasma dry etching. However, these transistors show a\nstrong positive threshold voltage (VT) shift with narrow channel widths of less\nthan 200 nm. Our results also show that transistors with thinner channel\nthicknesses have larger VT shifts associated with width scaling. Devices\nfabricated on a 6 nm thick MoS2 crystal underwent the transition from\ndepletion-mode to enhancement-mode."
    },
    {
        "anchor": "Quantized Adiabatic Charge Transport in a Carbon Nanotube: The coupling of a metallic Carbon nanotube to a surface acoustic wave (SAW)\nis proposed as a vehicle to realize quantized adiabatic charge transport in a\nLuttinger liquid system. We demonstrate that electron backscattering by a\nperiodic SAW potential, which results in miniband formation, can be achieved at\nenergies near the Fermi level. Electron interaction, treated in a Luttinger\nliquid framework, is shown to enhance minigaps and thereby improve current\nquantization. Quantized SAW induced current, as a function of electron density,\nchanges sign at half-filling.",
        "positive": "Valley to charge current conversion in graphene grain boundaries: The conduction properties of a grain boundary junction with Fermi velocity\nmismatch are analyzed. We provide a generalization of the Dirac Hamiltonian\nmodel taking into account the Fermi velocity gradient at the interface. General\nboundary conditions for the scattering problem are derived within the framework\nof the matching matrix method. We show that the scattering properties of the\ninterface, as predicted by the theory, strongly depend on the boundary\nconditions used. We demonstrate that when the valley degeneracy is broken a\ncharge current is established at the grain boundary interface. These findings\nprovide the working principle of a valley to charge current converter, which is\nrelevant for the emergent field of valleytronics."
    },
    {
        "anchor": "Magnetic Bloch Skyrmion Transport by Electric Fields in a Composite\n  Bilayer: We investigate a mechanical method to manipulate magnetic Bloch Skyrmions by\napplying an electric field in a composite chiral-magnetic (CM)/ferroelectric\n(FE) bilayer. The magnetoelectric coupling at the interface allows the electric\nfield to stimulate magnetic ordering. Therefore it offers the possibility to\ngenerate Skyrmions [Phys. Rev. B 94, 014311 (2016)]. Here, we design a movable\nand localized electric field source to drive skyrmion transport along the\nbilayer. A traveling velocity of the electric field source must be carefully\nchosen to show the stability and effciency of this process. The effects of high\nspeed operation will be discussed.",
        "positive": "Suppression of chaotic dynamics and localization of two-dimensional\n  electrons by a weak magnetic field: We study a two-dimensional motion of a charged particle in a weak random\npotential and a perpendicular magnetic field. The correlation length of the\npotential is assumed to be much larger than the de Broglie wavelength. Under\nsuch conditions, the motion on not too large length scales is described by\nclassical equations of motion. We show that the phase-space averaged diffusion\ncoefficient is given by Drude-Lorentz formula only at magnetic fields $B$\nsmaller than certain value $B_c$. At larger fields, the chaotic motion is\nsuppressed and the diffusion coefficient becomes exponentially small. In\naddition, we calculate the quantum-mechanical localization length as a function\nof $B$ in the minima of $\\sigma_{xx}$. At $B < B_c$ it is exponentially large\nbut decreases with increasing $B$. At $B > B_c$, the localization length drops\nprecipitously, and ceases to be exponentially large at a field $B_\\ast$, which\nis only slightly above $B_c$. Implications for the crossover from the\nShubnikov-de Haas oscillations to the quantum Hall effect are discussed."
    },
    {
        "anchor": "Hinge states in a system of coupled Rashba layers: We consider a system of stacked tunnel-coupled two-dimensional electron- and\nhole-gas layers with Rashba spin-orbit interactions subjected to a staggered\nZeeman field. The interplay of different intra-layer tunnel couplings results\nin a phase transition to a topological insulator phase in three dimensions\nhosting gapless surface states. The staggered Zeeman field further enriches the\ntopological phase diagram by generating a second-order topological insulator\nphase hosting gapless hinge states. The emergence of the topological phases is\nproven analytically in the regime of small Zeeman field and confirmed by\nnumerical simulations in the non-perturbative region of the phase diagram. The\ntopological phases are stable against external perturbations and disorder.",
        "positive": "Subsurface charge accumulation imaging of a quantum Hall liquid: The unusual properties of two-dimensional electron systems that give rise to\nthe quantum Hall effect have prompted the development of new microscopic models\nfor electrical conduction. The bulk properties of the quantum Hall effect have\nalso been studied experimentally using a variety of probes including transport,\nphotoluminescence, magnetization, and capacitance measurements. However, the\nfact that two-dimensional electron systems typically exist some distance (about\n100 nm) beneath the surface of the host semiconductor has presented an\nimportant obstacle to more direct measurements of microscopic electronic\nstructure in the quantum Hall regime. Here we introduce a cryogenic\nscanning-probe technique-- subsurface charge accumulation imaging-- that\npermits very high resolution examination of systems of mobile electrons inside\nmaterials. We use it to image directly the nanometer-scale electronic\nstructures that exist in the quantum Hall regime."
    },
    {
        "anchor": "Photovoltaic Hall effect in graphene: Response of electronic systems in intense lights (AC electric fields) to DC\nsource-drain fields is formulated with the Floquet method. We have then applied\nthe formalism to graphene, for which we show that a non-linear effect of a\ncircularly polarized light can open a gap in the Dirac cone, which leads to a\nphoto-induced dc Hall current. This is numerically confirmed for a graphene\nribbon attached to electrodes with the Keldysh Green's function.",
        "positive": "Heat Dissipation from Brownian Particles under Hydrodynamic Interactions: We study the non-equilibrium thermodynamics of single Brownian macromolecules\nimmersed in water solvent. They are under both a hydrodynamic interaction and a\nfeedback control on their movement by an external agent. The macromolecules are\ndescribed by a Langevin equation with a multiplicative noise. Work done by the\nmacromolecules on the water solvent is dissipated as heat. Thus, the heat is\nexpressed as the integration of an interacting force between the macromolecules\nand the water solvent along the position space trajectories of the\nmacromolecules. This integration is stochastic due to the Brownian motion of\nthe macromolecules. We show that the Stratonovich prescription of the\nintegration is the unique physical choice. We also show that thermodynamic\nquantities such as heat, work, and entropy production, are derived without any\nambiguity if both a diffusion matrix and external feedback control are known as\npriori."
    },
    {
        "anchor": "Theory of Photon Condensation in a Spatially-Varying Electromagnetic\n  Field: The realization of equilibrium superradiant quantum phases (photon\ncondensates) in a spatially-uniform quantum cavity field is forbidden by a\n\"no-go\" theorem stemming from gauge invariance. We here show that the no-go\ntheorem does not apply to spatially-varying quantum cavity fields. We find a\ncriterion for its occurrence that depends solely on the static, non-local\norbital magnetic susceptibility $\\chi_{\\rm orb}(q)$, of the electronic system\n(ES) evaluated at a cavity photon momentum $\\hbar q$. Only 3DESs satisfying the\nCondon inequality $\\chi_{\\rm orb}(q)>1/(4\\pi)$ can harbor photon condensation.\nFor the experimentally relevant case of two-dimensional (2D) ESs embedded in\nquasi-2D cavities the criterion again involves $\\chi_{\\rm orb}(q)$ but also the\nvertical size of the cavity. We use these considerations to identify electronic\nproperties that are ideal for photon condensation. Our theory is\nnon-perturbative in the strength of electron-electron interaction and therefore\napplicable to strongly correlated ESs.",
        "positive": "Loss and decoherence due to stray infrared light in superconducting\n  quantum circuits: We find that stray infrared light from the 4 K stage in a cryostat can cause\nsignificant loss in superconducting resonators and qubits. For devices shielded\nin only a metal box, we measured resonators with quality factors Q = 10^5 and\nqubits with energy relaxation times T_1=120 ns, consistent with a stray\nlight-induced quasiparticle density of 170-230 \\mu m^{-3}. By adding a second\nblack shield at the sample temperature, we found about an order of magnitude\nimprovement in performance and no sensitivity to the 4 K radiation. We also\ntested various shielding methods, implying a lower limit of Q = 10^8 due to\nstray light in the light-tight configuration."
    },
    {
        "anchor": "Quantitative Measurements of Giant and Quantized Microwave Faraday\n  Rotation: We report {\\it quantitative} microwave Faraday rotation measurements\nconducted with a high-mobility two-dimensional electron gas (2DEG) in a\nGaAs/AlGaAs semiconductor heterostructure. In a magnetic field, the Hall effect\nand the Faraday effect arise from the action of Lorentz force on electrons in\nthe 2DEG. As with the Hall effect, a classical Faraday effect is observed at\nlow magnetic field as well as a quantized Faraday effect at high magnetic\nfield. The high electron mobility of the 2DEG enables a giant single-pass\nFaraday rotation of $\\theta_F^{max} \\simeq 45^\\circ$ $(\\simeq0.8$~rad) to be\nachieved at a modest magnetic field of $B \\simeq 100$~mT. In the quantum\nregime, we find that the Faraday rotation $\\theta_F$ is quantized in units of\n$\\alpha^*= 2.80(4)\\alpha$, where $\\alpha\\simeq 1/137$ is the fine structure\nconstant. The enhancement in rotation quantum $\\alpha^* > \\alpha$ is attributed\nto electromagnetic confinement within a waveguide structure.",
        "positive": "Electronic beam shifts in monolayer graphene superlattice: Electronic analogue of generalized Goos-H\\\"{a}nchen shifts is investigated in\nthe monolayer graphene superlattice with one-dimensional periodic potentials of\nsquare barriers. It is found that the lateral shifts for the electron beam\ntransmitted through the monolayer graphene superlattice can be negative as well\nas positive near the band edges of zero-$\\bar{k}$ gap, which are different from\nthose near the band edges of Bragg gap. These negative and positive beam shifts\nhave close relation to the Dirac point. When the condition $q_A d_A= -q_B d_B=\nm \\pi$ ($m=1,2,3...$) is satisfied, the beam shifts can be controlled from\nnegative to positive when the incident energy is above the Dirac point, and\nvice versa. In addition, the beam shifts can be greatly enhanced by the defect\nmode inside the zero-$\\bar{k}$ gap. These intriguing phenomena can be verified\nin a relatively simple optical setup, and have potential applications in the\ngraphene-based electron wave devices."
    },
    {
        "anchor": "Kohn Anomalies in Graphene Nanoribbons: The quantum corrections to the energies of the $\\Gamma$ point optical phonon\nmodes (Kohn anomalies) in graphene nanoribbons are investigated. We show\ntheoretically that the longitudinal optical modes undergo a Kohn anomaly\neffect, while the transverse optical modes do not. In relation to Raman\nspectroscopy, we show that the longitudinal modes are not Raman active near the\nzigzag edge, while the transverse optical modes are not Raman active near the\narmchair edge. These results are useful for identifying the orientation of the\nedge of graphene nanoribbons by G band Raman spectroscopy, as is demonstrated\nexperimentally. The differences in the Kohn anomalies for nanoribbons and for\nmetallic single wall nanotubes are pointed out, and our results are explained\nin terms of pseudospin effects.",
        "positive": "Graphene Phase Modulator: We demonstrate a 10Gb/s Graphene Phase Modulator (GPM) integrated in a\nMach-Zehnder interferometer configuration. This is a compact device, with a\nphase-shifter length of only 300$\\mu$m, and 35dB extinction ratio. The GPM has\nmodulation efficiency of 0.28Vcm, one order of magnitude higher compared to\nstate-of-the-art depletion p-n junction Si phase modulators. Our GPM operates\nwith 2V peak-to-peak driving voltage in a push-pull configuration, and it has\nbeen tested in a binary transmission of a non-return-to-zero data stream over\n50km single mode fibre. This device is the key building block for\ngraphene-based integrated photonics, enabling compact and energy efficient\nhybrid Si-graphene modulators for telecom, datacom and other applications"
    },
    {
        "anchor": "Photovoltaic anomalous Hall effect in line-node semimetals: We theoretically study the circularly polarized light-induced Floquet state\nin line-node semimetals with time-reversal symmetry and inversion symmetry. It\nis found that the Floquet state can show the photovoltaic anomalous Hall effect\nwhen an applied circularly polarized light gaps out the line node in the bulk\nand leave Weyl point nodes. The Hall conductivity is sensitive to the location\nof Fermi level: When the Fermi level locates at the node, the Hall conductivity\ndepends on the radius of line node and is nearly independent of the intensity\nof light. Away from the line node, the Hall conductivity is dependent on the\nintensity of light. Such a sensitive Fermi-level dependence of the Hall\nconductivity in the presence of a weak laser intensity can have applications in\nphototransistors based on thin films of line-node semimetals.",
        "positive": "Ultra-sensitive Hall sensors based on graphene encapsulated in hexagonal\n  boron nitride: The encapsulation of graphene in hexagonal boron nitride provides graphene on\nsubstrate with excellent material quality. Here, we present the fabrication and\ncharacterization of Hall sensor elements based on graphene boron nitride\nheterostructures, where we gain from high mobility and low charge charier\ndensity at room temperature. We show a detailed device characterization\nincluding Hall effect measurements under vacuum and ambient conditions. We\nachieve a current- and voltage-related sensitivity of up to 5700 V/AT and 3\nV/VT, respectively, outpacing state-of- the-art silicon and III/V Hall sensor\ndevices. Finally, we extract a magnetic resolution limited by low frequency\nelectric noise of less than 50 nT/pHz making our graphene sensors highly\ninteresting for industrial applications."
    },
    {
        "anchor": "Anisotropic Andreev reflection in semi-Dirac materials: In the framework of Bogoliubov-de Gennes equation, we theoretically study the\nAndreev reflection in normal-superconducting junctions based on semi-Dirac\nmaterials. Owing to the intrinsic anisotropy of semi-Dirac materials, the\nconfiguration of Andreev reflection and differential conductance are strongly\norientation-dependent. For the transport along the linear dispersion direction,\nthe differential conductance exhibits a clear crossover from retro Andreev\nreflection to specular Andreev reflection with an increasing bias-voltage, and\nthe differential conductance oscillates without a decaying profile when the\ninterfacial barrier strength increases. However, for the transport along the\nquadratic dispersion direction, the boundary between the retro Andreev\nreflection and specular Andreev reflection is ambiguous, and the differential\nconductance decays with increasing the momentum mismatch or the interfacial\nbarrier strength. We illustrate the pseudo-spin textures to reveal the\nunderling physics behind the anisotropic coherent transport properties. These\nresults enrich the understanding of the superconducting coherent transport in\nsemi-Dirac materials.",
        "positive": "Conductance oscillations of antiferromagnetic layer tunnel junctions: We study the conductance oscillation of an antiferromagnetic layer tunnel\njunction composed of antiferromagnetic topological insulators (MTIs) such as\nMnBi$_{2}$Te$_{4}$. In presence of an in-plane magnetic field, we find that the\ntwo terminal differential conductance across the junction oscillates as a\nfunction of field strength. Notably, the quantum interference at weak fields\nfor the odd-layer MTIs is distinctive from the even-layer MTIs due to the\nscattering phase difference. Consequently, the differential conductance is\nvanishing (maximized) at integer magnetic flux quanta for even-layer\n(odd-layer) junction. The conductance oscillations manifest the layer-dependent\nquantum interference in which symmetries and scattering phases play essential\nroles. In numerical calculations, we observe that the quantum interference\nundergoes an evolution from SQUID-like patterns to Fraunhofer-like oscillations\nas the junction length increases."
    },
    {
        "anchor": "Quantum Interference Effects in InAs Semiconductor Nanowires: We report quantum interference effects in InAs semiconductor nanowires\nstrongly coupled to superconducting electrodes. In the normal state, universal\nconductance fluctuations are investigated as a function of magnetic field,\ntemperature, bias and gate voltage. The results are found to be in good\nagreement with theoretical predictions for weakly disordered one-dimensional\nconductors. In the superconducting state, the fluctuation amplitude is enhanced\nby a factor up to ~ 1.6, which is attributed to a doubling of charge transport\nvia Andreev reflection. At a temperature of 4.2 K, well above the Thouless\ntemperature, conductance fluctuations are almost entirely suppressed, and the\nnanowire conductance exhibits anomalous quantization in steps of e^{2}/h.",
        "positive": "Andreev levels spectroscopy of topological three-terminal junctions: We calculate the differential conductance at a probe inserted in the weak\nlink of a topological Josephson junction, consisting of a semiconducting\nnanowire deposited on top of two separated superconductors. Our aim is to\nunderstand how the peculiar features in the spectrum of Andreev bound states,\narising due to the presence of Majorana bound states at the ends of the two\ntopological superconducting wires defining the junction, can be determined\nthrough a measurement of the differential conductance. We find that when the\nprobe allows a single propagating mode, the differential conductance presents a\ndip at zero voltage of zero conductance close to the position where the\nspectrum exhibits the topologically protected crossing. This can be viewed as a\nsignature of the presence of Majorana states, which does not require fermion\nparity conservation and is robust against parameters' changes, as well as\ndisorder. On the contrary, when the probe allows two or more propagating modes\nthe differential conductance resembles the spectrum of Andreev bound states.\nThis has been established making use of both numerical and analytical methods."
    },
    {
        "anchor": "Majorana bound states in topological insulators without a vortex: We consider a three-dimensional topological insulator (TI) wire with a\nnon-uniform chemical potential induced by gating across the cross-section. This\ninhomogeneity in chemical potential lifts the degeneracy between two\none-dimensional surface state subbands. A magnetic field applied along the\nwire, due to orbital effects, breaks time-reversal symmetry and lifts the\nKramers degeneracy at zero-momentum. If placed in proximity to an $s$-wave\nsuperconductor, the system can be brought into a topological phase at\nrelatively weak magnetic fields. Majorana bound states (MBSs), localized at the\nends of the TI wire, emerge and are present for an exceptionally large region\nof parameter space in realistic systems. Unlike in previous proposals, these\nMBSs occur without the requirement of a vortex in the superconducting pairing\npotential, which represents a significant simplification for experiments. Our\nresults open a pathway to the realisation of MBSs in present day TI wire\ndevices.",
        "positive": "Topologically protected Landau levels in bilayer graphene in finite\n  electric fields: The zero-energy Landau level of bilayer graphene is shown to be anomalously\nsharp (delta-function like) against bond disorder as long as the disorder is\ncorrelated over a few lattice constants.The robustness of the zero-mode anomaly\ncan be attributed to the preserved chiral symmetry. Unexpectedly, even when we\napply a finite potential difference (i.e., an electric field) between the top\nand the bottom layers, the valley-split $n=0$ Landau levels remain anomalously\nsharp although they are now shifted away from the zero energy, while the $n=1$\nLandau levels exhibit the usual behavior."
    },
    {
        "anchor": "Notes on the minimal longitudinal dc conductivity of perfect bilayer\n  graphene: We calculated the minimal longitudinal conductivity in prefect single and\nbilayer graphene by extending the two methods developed for Dirac fermion gas\nby A. W. W. Ludwig et al. in Phys. Rev. B {\\bf 50}, 7526 (1994). Using the Kubo\nformula which was originally applied for spintronic systems we obtain\n$\\sigma^{\\text min}_{xx}= (J \\pi /2) e^2/h$ while from the other formula used\nin the above mentioned work we find $\\bar{\\sigma}^{\\text min}_{xx}= (4J/\\pi)\ne^2/h$, where J=1 for single layer and J=2 for bilayer graphene. The two\nuniversal values are different although they are numerically close to each\nother. Our two results are in the same order of magnitude as that of\nexperiments and for single layer case one of our result agrees many earlier\ntheoretical predictions. However, for bilayer graphene only two studies are\nknown with predictions for the minimal conductivity different from our\ncalculated values. Similarly to the single layer case, the physical origin of\nthe minimal conductivity in bilayer graphene is also rooted back to the\nintrinsic disorder induced by the Zitterbewegung which is related to the\ntrembling motion of the electron.",
        "positive": "Tracing non-Abelian anyons via impurity particles: Non-Abelian excitations are an interesting feature of many fractional quantum\nHall phases, including those phases described by the Moore-Read (or Pfaffian)\nwave function. However, the detection of the non-Abelian quasiparticles is\nchallenging. Here, we consider a system described by the Moore-Read wave\nfunction, and assume that impurity particles bind to its quasiholes. Then, the\nangular momentum of the impurities, reflected also by the impurity density,\nprovides a useful witness of the physics of the non-Abelian excitations. By\ndemanding that the impurities are constrained to the lowest Landau level, we\nare able to write down the corresponding many-body wave function describing\nboth the Moore-Read liquid and the impurities. Through Monte Carlo sampling we\ndetermine the impurity angular momentum, and we show that it suggests a\nquantum-statistical parameter $\\alpha = a\\nu -b +P/2$ for the quasiholes, where\n$\\alpha$ ranges from $0$ for bosons to $1$ for fermions. A reasonable agreement\nwith the Monte Carlo results is obtained for $a=1/4$, $b=1/8$ and $P=0,1$\ndepending on the parity of the particle number in the Moore-Read liquid. This\nparity-dependence of the angular momentum serves as an unambiguous\ndemonstration of the non-Abelian nature of the excitations. In addition to the\nstudies of excitations in the Moore-Read liquid, we also apply our scheme to\nLaughlin liquids, for which we focus on interacting bosonic impurities. With\nthis, the impurities themselves form Laughlin states, which allows for a study\nof hierarchical fractional quantum Hall states."
    },
    {
        "anchor": "Field-effect and frequency dependent transport in semiconductor-enriched\n  single-wall carbon nanotube network device: The electrical and optical response of a field-effect device comprising a\nnetwork of semiconductor-enriched single-wall carbon nanotubes, gated with\nsodium chloride solution is investigated. Field-effect is demonstrated in a\ndevice that uses facile fabrication techniques along with a small-ion as the\ngate electrolyte - and this is accomplished as a result of the semiconductor\nenhancement of the tubes. The optical transparency and electrical resistance of\nthe device are modulated with gate voltage. A time-response study of the\nmodulation of optical transparency and electrical resistance upon application\nof gate voltage suggests the percolative charge transport in the network. Also\nthe ac response in the network is investigated as a function of frequency and\ntemperature down to 5 K. An empirical relation between onset frequency and\ntemperature is determined.",
        "positive": "Quantum Hole Digging in Magnetic Molecular Clusters: Below 360 mK, Fe8 magnetic molecular clusters are in the pure quantum\nrelaxation regime. We showed recently that the predicted ``square-root time''\nrelaxation is obeyed, allowing us to develop a new method for watching the\nevolution of the distribution of molecular spin states in the sample. We\nmeasured the distribution P(H) of molecules which are in resonance at the\napplied field H. Tunnelling initially causes rapid transitions of molecules,\nthereby ``digging a hole'' in P(H). For small initial magnetisation values, the\nhole width shows an intrinsic broadening which may be due to nuclear spins. We\npresent here hole digging measurements in the thermal activated regime which\nmay allow to study the effect of spin-phonon coupling."
    },
    {
        "anchor": "Crossover in the two-impurity Kondo model induced by direct charge\n  tunneling: Quantum critical behavior in the two-impurity Kondo model requires the\ndistinct separation of two scales, T_K >> T*, where T_K is the Kondo\ntemperature and T* is the scale at which the system renormalizes away from the\nquantum critical point to a stable Fermi liquid fixed point. We provide a\nderivation of T* based on the renormalization group to lowest order. This\nresult is confirmed by a numerical renormalization group (NRG) analysis which\nsupplements the analytic derivation with additional quantitative precision. The\nform of the low-energy Fermi liquid fixed point is derived and subsequently\nconfirmed by the NRG. We discuss implications for series double quantum dot\nsystems.",
        "positive": "Spin Aharonov-Bohm effect and topological spin transistor: Ever since its discovery, the electron spin has only been measured or\nmanipulated through the application of an electromagnetic force acting on the\nassociated magnetic moment. In this work, we propose a spin Aharonov-Bohm\neffect in which the electron spin is controlled by a magnetic flux while no\nelectromagnetic field is acting on the electron. Such a nonlocal spin\nmanipulation is realized in an Aharonov-Bohm ring made from the recently\ndiscovered quantum spin Hall insulator, by taking advantage of the defining\nproperty of the quantum spin Hall edge states: the one-to-one correspondence\nbetween spin polarization and direction of propagation. The proposed setup can\nbe used to realize a new spintronics device, the topological spin transistor,\nin which the spin rotation is completely controlled by a magnetic flux of\nhc/2e, independently of the details of the sample."
    },
    {
        "anchor": "Efficient Edelstein effects in one-atom-layer Tl-Pb compound: We have investigated direct and inverse Edelstein effects in a one-atom-layer\nTl-Pb compound with a large Rashba-type spin splitting. In spin pumping\nexperiments at room temperature, spin-to-charge conversion voltage due to the\ninverse Edelstein effect is clearly observed in Py/Cu/Tl-Pb trilayer samples.\nTo confirm efficient spin-charge interconversion in Tl-Pb compounds, the direct\nEdelstein effect is also studied in the same trilayer samples by measuring\nmodulation of the effective magnetization damping in the Py layer via the\ncharge-to-spin conversion in the Tl-Pb layer. Using both the results of direct\nand inverse Edelstein effects, the Edelstein length is estimated to be ~0.1 nm\nfor Tl-Pb compounds.",
        "positive": "Thermomechanical bistability of phase-transition oscillators driven by\n  near-field heat exchange: Systems with multistable equilibrium states are of tremendous importance in\ninformation science to conceive logic gates. Here we predict that simple\nphase-transition oscillators driven by near-field heat exchanges have a\nbistable thermomechanical behavior around their critical temperature, opening\nso the way to a possible boolean treatment of information from heat flux at\nmicroscale."
    },
    {
        "anchor": "On-demand confinement of semiconductor excitons by all-optical control: In condensed-matter physics, remarkable advances have been made with atomic\nsystems by establishing a thorough control over cooling and trapping\ntechniques. In semiconductors, this method may also provide a deterministic\napproach to reach the long standing goal of harnessing collective quantum\nphenomena with exciton gases. While long-lived excitons are simply cooled to\nvery low temperatures using cryogenic apparatus, engineering confining\npotentials has been a challenging task. This degree of control was only\nachieved recently with devices realized by highly demanding nano-fabrication\nprocesses. Here, we demonstrate an alternative to this technology and show how\na proper optical excitation allows to manipulate in-situ the exciton transport.\nOur approach is based on the optically controlled injection and spatial\npatterning of charges trapped in a field-effect device. Thus, electric field\ngradients are created and implement microscopic traps or anti-traps for the\nexcitons dipole. Accordingly, any confinement geometry can be realized by\nshaping the spatial profile of a laser excitation. Hence, we succeed in\ntrapping exciton gases in a density range where quantum correlations are\npredicted at our very low bath temperature.",
        "positive": "On the way to meet the experimental observation of persistent current in\n  a mesoscopic cylinder: A mean field study: The behavior of persistent current in a mesoscopic cylinder threaded by an\nAharonov-Bohm flux $\\phi$ is carefully investigated within a Hartree-Fock mean\nfield approach. We examine the combined effect of second-neighbor hopping\nintegral and Hubbard correlation on the enhancement of persistent current in\npresence of disorder. A significant change in current amplitude is observed\ncompared to the traditional nearest-neighbor hopping model and the current\namplitude becomes quite comparable to experimental realizations. Our analysis\nis found to exhibit several interesting results which have so far remained\nunaddressed."
    },
    {
        "anchor": "Topological Band Engineering of Graphene Nanoribbons: Topological insulators (TIs) are an emerging class of materials that host\nhighly robust in-gap surface/interface states while maintaining an insulating\nbulk. While most notable scientific advancements in this field have been\nfocused on TIs and related topological crystalline insulators in 2D and 3D,\nmore recent theoretical work has predicted the existence of 1D\nsymmetry-protected topological phases in graphene nanoribbons (GNRs). The\ntopological phase of these laterally-confined, semiconducting strips of\ngraphene is determined by their width, edge shape, and the terminating unit\ncell, and is characterized by a Z2 invariant (similar to 1D solitonic systems).\nInterfaces between topologically distinct GNRs characterized by different Z2\nare predicted to support half-filled in-gap localized electronic states which\ncan, in principle, be utilized as a tool for material engineering. Here we\npresent the rational design and experimental realization of a\ntopologically-engineered GNR superlattice that hosts a 1D array of such states,\nthus generating otherwise inaccessible electronic structure. This strategy also\nenables new end states to be engineered directly into the termini of the 1D GNR\nsuperlattice. Atomically-precise topological GNR superlattices were synthesized\nfrom molecular precursors on a Au(111) surface under ultra-high vacuum (UHV)\nconditions and characterized by low temperature scanning tunneling microscopy\n(STM) and spectroscopy (STS). Our experimental results and first-principles\ncalculations reveal that the frontier band structure of these GNR superlattices\nis defined purely by the coupling between adjacent topological interface\nstates. This novel manifestation of 1D topological phases presents an entirely\nnew route to band engineering in 1D materials based on precise control of their\nelectronic topology, and is a promising platform for future studies of 1D\nquantum spin physics.",
        "positive": "Cooling and Self-Oscillation in a Nanotube Electro-Mechanical Resonator: Nanomechanical resonators are used with great success to couple mechanical\nmotion to other degrees of freedom, such as photons, spins, and electrons.\nMechanical vibrations can be efficiently cooled and amplified using photons,\nbut not with other degrees of freedom. Here, we demonstrate a simple yet\npowerful method for cooling, amplification, and self-oscillation using\nelectrons. This is achieved by applying a constant (DC) current of electrons\nthrough a suspended nanotube in a dilution fridge. We demonstrate cooling down\nto $4.6\\pm 2.0$ quanta of vibrations. We also observe self-oscillation, which\ncan lead to prominent instabilities in the electron transport through the\nnanotube. We attribute the origin of the observed cooling and self-oscillation\nto an electrothermal effect. This work shows that electrons may become a useful\nresource for quantum manipulation of mechanical resonators."
    },
    {
        "anchor": "Real-space observation of skyrmion clusters with mutually orthogonal\n  skyrmion tubes: We report the discovery and direct visualization of skyrmion clusters with\nmutually-orthogonal orientations of constituent isolated skyrmions in chiral\nliquid crystals and ferromagnets. We show that the nascent conical state\nunderlies attracting inter-skyrmion potential, whereas an encompassing\nhomogeneous state leads to the repulsive skyrmion-skyrmion interaction. The\ncrossover between different regimes of skyrmion interaction could be identified\nupon changing layer thickness and/or the surface anchoring. We develop a\nphenomenological theory describing two types of skyrmions and the underlying\nmechanisms of their interaction. We show that isolated horizontal skyrmions\nwith the same polarity may approach a vertical isolated skyrmion from both\nsides and thus constitute two energetically-different configurations which are\nalso observed experimentally. In an extreme regime of mutual attraction, the\nskyrmions wind around each other forming compact superstructures with\nundulations. We also indicate that our numerical simulations on skyrmion\nclusters are valid in a parameter range corresponding to the A-phase region of\ncubic helimagnets.",
        "positive": "Electrically switchable tunneling across a graphene pn junction:\n  evidence for canted antiferromagnetic phase in $\u03bd=0$ state: The ground state of a graphene sheet at charge neutrality in a perpendicular\nmagnetic field remains enigmatic, with various experiments supporting canted\nantiferromagnetic, bond ordered, and even charge density wave phases. A\npromising avenue to elucidating the nature of this state is to sandwich it\nbetween regions of different filling factors, and study spin-dependent\ntunneling across the edge modes at the interfaces. Here we report on tunnel\ntransport through a $\\nu=0$ region in a graphite-gated, hexagonal boron nitride\n($hBN$) encapsulated monolayer graphene device, with the $\\nu=0$ strip\nsandwiched by spin-polarized $\\nu=\\pm1$ quantum Hall states. We observe finite\ntunneling ($t \\sim 0.3-0.6$) between the $\\nu=\\pm1$ edges at not too small\nmagnetic fields ($B>3T$) and low tunnel bias voltage ($<30-60\\mu V$), which is\nsurprising because electrons at the edge states nominally have opposite spins.\nHartree-Fock calculations elucidate these phenomena as being driven by the\nformation of a CAF order parameter in the $\\nu=0$ region at zero bias (for wide\nenough junctions) leading to non-orthogonal spins at the edges. Remarkably,\nthis tunneling can be controllably switched off by increasing bias; bias\nvoltage leads to a pileup of charge at the junction, leading to a collapse of\nthe CAF order and a suppression of the tunneling."
    },
    {
        "anchor": "Anomalous Interaction Dependence in Magnetism of Graphene Nanoribbons\n  with Zigzag Edges: Properties in magnetic ordered states of graphene nanoribbons with zigzag\nshaped edges are investigated by applying mean-field approximation to the\nHubbard model with on-site repulsion $U$. We observe that magnetic moments and\ncritical temperature show anomalous power-law dependences as a function of $U$;\nthe actual values of the power are determined by only the width of ribbons.\nSuch singular behaviours are found to be due to localized nature of the\nelectronic states close to Fermi energy.",
        "positive": "Vortex molecules in coherently coupled two-component Bose-Einstein\n  condensates: A vortex molecule is predicted in rotating two-component Bose-Einstein\ncondensates whose internal hyperfine states are coupled coherently by an\nexternal field. A vortex in one component and that in the other are connected\nby a domain wall of the relative phase, constituting a \"vortex molecule\", which\nfeatures a nonaxisymmetric (pseudo)spin texture with a pair of merons. The\nbinding mechanism of the vortex molecule is discussed based on a generalized\nnonlinear sigma model and a variational ansatz. The anisotropy of vortex\nmolecules is caused by the difference in the scattering lengths, yielding a\ndistorted vortex-molecule lattice in fast rotating condensates."
    },
    {
        "anchor": "A low-loss, broadband antenna for efficient photon collection from a\n  coherent spin in diamond: We report the creation of a low-loss, broadband optical antenna giving highly\ndirected output from a coherent single spin in the solid-state. The device, the\nfirst solid-state realization of a dielectric antenna, is engineered for\nindividual nitrogen vacancy (NV) electronic spins in diamond. We demonstrate a\ndirectionality close to 10. The photonic structure preserves the high spin\ncoherence of single crystal diamond (T2>100us). The single photon count rate\napproaches a MHz facilitating efficient spin readout. We thus demonstrate a key\nenabling technology for quantum applications such as high-sensitivity\nmagnetometry and long-distance spin entanglement.",
        "positive": "Molecular collapse in monolayer graphene: Atomic collapse is a phenomenon inherent to relativistic quantum mechanics\nwhere electron states dive in the positron continuum for highly charged nuclei.\nThis phenomenon was recently observed in graphene. Here we investigate a novel\ncollapse phenomenon when multiple sub- and supercritical charges of equal\nstrength are put close together as in a molecule. We construct a phase diagram\nwhich consists of three distinct regions: 1) subcritical, 2) frustrated atomic\ncollapse, and 3) molecular collapse. We show that the single impurity atomic\ncollapse resonances rearrange themselves to form molecular collapse resonances\nwhich exhibit a distinct quasi-bonding, anti-bonding and non-bonding character.\nHere we limit ourselves to a systems consisting of two and three charges. We\nshow that by tuning the distance between the charges and their strength a high\ndegree of control over the molecular collapse resonances can be achieved."
    },
    {
        "anchor": "Surface Enhanced Raman Spectroscopy of Graphene: Surface enhanced Raman scattering (SERS) exploits surface plasmons induced by\nthe incident field in metallic nanostructures to significantly increase the\nRaman intensity. Graphene provides the ideal prototype two dimensional (2d)\ntest material to investigate SERS. Its Raman spectrum is well known, graphene\nsamples are entirely reproducible, height controllable down to the atomic\nscale, and can be made virtually defect-free. We report SERS from graphene, by\ndepositing arrays of Au particles of well defined dimensions on\ngraphene/SiO$_2$(300nm)/Si. We detect significant enhancements at 633nm. To\nelucidate the physics of SERS, we develop a quantitative analytical and\nnumerical theory. The 2d nature of graphene allows for a closed-form\ndescription of the Raman enhancement. This scales with the nanoparticle cross\nsection, the fourth power of the Mie enhancement, and is inversely proportional\nto the tenth power of the separation between graphene and the nanoparticle. One\nconsequence is that metallic nanodisks are an ideal embodiment for SERS in 2d.",
        "positive": "Theory of coherent optical nonlinearities of intersubband transitions in\n  semiconductor quantum wells: We theoretically study the coherent nonlinear response of electrons confined\nin semiconductor quantum wells under the effect of an electromagnetic radiation\nclose to resonance with an intersubband transition. Our approach is based on\nthe time-dependent Schr\\\"odinger-Poisson equation stemming from a Hartree\ndescription of Coulomb-interacting electrons. This equation is solved by\nstandard numerical tools and the results are interpreted in terms of\napproximated analytical formulas. For growing intensity, we observe a redshift\nof the effective resonance frequency due to the reduction of the electric\ndipole moment and the corresponding suppression of the depolarization shift.\nThe competition between coherent nonlinearities and incoherent saturation\neffects is discussed. The strength of the resulting optical nonlinearity is\nestimated across different frequency ranges from mid-IR to THz with an eye to\nongoing experiments on Bose-Einstein condensation of intersubband polaritons\nand to the speculative exploration of quantum optical phenomena such as\nsingle-photon emission in the mid-IR and THz windows."
    },
    {
        "anchor": "A novel method for the injection and manipulation of magnetic charge\n  states in nanostructures: Realising the promise of next-generation magnetic nanotechnologies is\ncontingent on the development of novel methods for controlling magnetic states\nat the nanoscale. There is currently demand for simple and flexible techniques\nto access exotic magnetisation states without convoluted fabrication and\napplication processes. 360 degree domain walls (metastable twists in\nmagnetisation separating two domains with parallel magnetisation) are one such\nstate, which is currently of great interest in data storage and magnonics.\nHere, we demonstrate a straightforward and powerful process whereby a moving\nmagnetic charge, provided experimentally by a magnetic force microscope tip,\ncan write and manipulate magnetic charge states in ferromagnetic nanowires. The\nmethod is applicable to a wide range of nanowire architectures with\nconsiderable benefits over existing techniques. We confirm the method's\nefficacy via the injection and spatial manipulation of 360 degree domain walls\nin Py and Co nanowires. Experimental results are supported by micromagnetic\nsimulations of the tip-nanowire interaction.",
        "positive": "Experimental and theoretical analyses of strongly polarized photon\n  emission from non-polar InGaN quantum dots: We present a comprehensive investigation of the polarization properties of\nnon-polar a-plane InGaN quantum dots (QDs) and their origin with statistically\nsignificant experimental data and rigorous k.p modelling. The unbiased\nselection and study of 180 individual QDs allow us to compute an average\npolarization degree of 0.90, with a standard deviation of only 0.08. When\ncoupled with theoretical insights, we show that a-plane InGaN QDs are highly\ninsensitive to size differences, shape anisotropies, and indium content\nfluctuations. Furthermore, 91% of the studied QDs exhibit a polarization axis\nalong the crystal [1-100] axis, with the other 9% polarized orthogonal to this\ndirection. When coupled with their ability to emit single-photons, a-plane QDs\nare good candidates for the generation of linearly polarized single-photons, a\nfeature attractive for quantum cryptography protocols."
    },
    {
        "anchor": "Critical Collapse of the Exchange Enhanced Spin Splitting in 2-D Systems: The critical filling factor v_c where Shubnikov-de Haas oscillations become\nspin split is investigated for a set of GaAs-GaAlAs heterojunctions. Finite\ntemperature magnetoresistance measurements are used to extract the value of v_c\nat zero temperature. The critically point is where the disorder potential has\nthe same magnitude as the exchange energy, leading to the empirical\nrelationship v_c = g* n t h / 2 m_0. This is valid for all the samples studied,\nwhere the density n and single particle lifetime t both vary by more than an\norder of magnitude and g* the exchange enhanced g-factor has a weak dependence\non density. For each sample the spin gap energy shows a linear increase with\nmagnetic field. Experiments in tilted magnetic field show the spin gap is the\nsum of the bare Zeeman energy and an exchange term. This explains why\nmeasurements of the enhanced g-factor from activation energy studies in\nperpendicular field and the coincidence method in tilted fields have previously\ndisagreed.",
        "positive": "Spontaneous symmetry breaking in single and molecular quantum dots: Classes of spontaneous symmetry breaking at zero and low magnetic fields in\nsingle quantum dots (QD's) and quantum dot molecules (QDM's) are discussed in\nrelation to the ratio R_W between the interelectron Coulomb repulsion and the\nharmonic confinement, using spin-and-Space unrestricted Hartree-Fock\ncalculations. These include: Wigner crystallization for R_W > 1, and formation\nof non-crystallized electron puddles localized on the individual dots in QDM's,\nas well as spin-density waves in single QD's, for R_W < 1.\n  Erratum:\n  Subsequent to the the publication of our Letter, we have performed further\nsystematic spin-and-space unrestricted Hartree-Fock calculations. While the\nbehavior and magnitudes of the addition energies shown in our Letter are\nmaintained, as well as our finding pertaining to the prevalent violation of\nHund's first rule, our improved calculations yield in certain instances\ndifferent spin polarizations."
    },
    {
        "anchor": "Magnetic breakdown spectrum of a Kramers-Weyl semimetal: We calculate the Landau levels of a Kramers-Weyl semimetal thin slab in a\nperpendicular magnetic field $B$. The coupling of Fermi arcs on opposite\nsurfaces broadens the Landau levels with a band width that oscillates\nperiodically in $1/B$. We interpret the spectrum in terms of a one-dimensional\nsuperlattice induced by magnetic breakdown at Weyl points. The band width\noscillations may be observed as $1/B$-periodic magnetoconductance oscillations,\nat weaker fields and higher temperatures than the Shubnikov-de Haas\noscillations due to Landau level quantization. No such spectrum appears in a\ngeneric Weyl semimetal, the Kramers degeneracy at time-reversally invariant\nmomenta is essential.",
        "positive": "High-throughput techniques for measuring the spin Hall effect: The spin Hall effect in heavy-metal thin films is routinely employed to\nconvert charge currents into transverse spin currents and can be used to exert\ntorque on adjacent ferromagnets. Conversely, the inverse spin Hall effect is\nfrequently used to detect spin currents by charge currents in spintronic\ndevices up to the terahertz frequency range. Numerous techniques to measure the\nspin Hall effect or its inverse were introduced, most of which require\nextensive sample preparation by multi-step lithography. To enable rapid\nscreening of materials in terms of charge-to-spin conversion, suitable\nhigh-throughput methods for measuring the spin Hall angle are required. Here,\nwe compare two lithography-free techniques, terahertz emission spectroscopy and\nbroadband ferromagnetic resonance, to standard harmonic Hall measurements and\ntheoretical predictions using the binary-alloy series Au$_x$Pt$_{1-x}$ as\nbenchmark system. Despite being highly complementary, we find that all three\ntechniques yield a spin Hall angle with approximately the same $x$~dependence,\nwhich is also consistent with first-principles calculations. Quantitative\ndiscrepancies are discussed in terms of magnetization orientation and\ninterfacial spin-memory loss."
    },
    {
        "anchor": "Phonons as a platform for non-Abelian braiding and its manifestation in\n  layered silicates: Topological phases of matter have revolutionised the fundamental\nunderstanding of band theory and hold great promise for next-generation\ntechnologies such as low-power electronics or quantum computers. Single-gap\ntopologies have been extensively explored, and a large number of materials have\nbeen theoretically proposed and experimentally observed. These ideas have\nrecently been extended to multi-gap topologies with band nodes that carry\nnon-Abelian charges, characterised by invariants that arise by the momentum\nspace braiding of such nodes. However, the constraints placed by the\nFermi-Dirac distribution to electronic systems have so far prevented the\nexperimental observation of multi-gap topologies in real materials. Here, we\nshow that multi-gap topologies and the accompanying phase transitions driven by\nbraiding processes can be readily observed in the bosonic phonon spectra of\nknown monolayer silicates. The associated braiding process can be controlled by\nmeans of an electric field and epitaxial strain, and involves, for the first\ntime, more than three bands. Finally, we propose that the band inversion\nprocesses at the $\\Gamma$ point can be tracked by following the evolution of\nthe Raman spectrum, providing a clear signature for the experimental\nverification of the band inversion accompanied by the braiding process.",
        "positive": "van der Waals Heterostructures of Germanene, Stanene and Silicene with\n  Hexagonal Boron Nitride and Their Topological Domain Walls: We investigate van der Waals (vdW) heterostructures made of germanene,\nstanene or silicene with hexagonal Boron Nitride (h-BN). The intriguing\ntopological properties of these buckled honeycomb materials can be maintained\nand further engineered in the heterostructures, where the competition between\nthe substrate effect and external electric fields can be used to control the\ntunable topological phase transitions. Using such heterostructures as building\nblocks, various vdW topological domain walls (DW) are designed, along which\nthere exist valley polarized quantum spin Hall edge states or\nvalley-contrasting edge states which are protected by valley(spin)- resolved\ntopological charges and can be tailored by the patterning of the\nheterojunctions and by external fields."
    },
    {
        "anchor": "Dominant electron-phonon scattering mechanisms in $n$-type PbTe from\n  first principles: We present an \\emph{ab-initio} study that identifies the main electron-phonon\nscattering channels in $n$-type PbTe. We develop an electronic transport model\nbased on the Boltzmann transport equation within the transport relaxation time\napproximation, fully parametrized from first-principles calculations that\naccurately describe the dispersion of the electronic bands near the band gap.\nOur computed electronic mobility as a function of temperature and carrier\nconcentration is in good agreement with experiments. We show that longitudinal\noptical phonon scattering dominates electronic transport in $n$-type PbTe,\nwhile acoustic phonon scattering is relatively weak. We find that scattering\ndue to soft transverse optical phonons is by far the weakest scattering\nmechanism, due to the symmetry-forbidden scattering between the conduction band\nminima and the zone center soft modes. Soft phonons thus play the key role in\nthe high thermoelectric figure of merit of $n$-type PbTe: they do not degrade\nits electronic transport properties although they strongly suppress the lattice\nthermal conductivity. Our results suggest that materials like PbTe with soft\nmodes that are weakly coupled with the electronic states relevant for transport\nmay be promising candidates for efficient thermoelectric materials.",
        "positive": "Nanoscale electromagnetism with the boundary element method: In Yang et al. [Nature 576, 248 (2019)], the authors introduced a general\ntheoretical framework for nanoscale electromagnetism based on Feibelman\nparameters. Here quantum effects of the optically excited electrons at the\ninterface between two materials are lumped into two complex-valued and\nfrequency-dependent parameters, which can be incorporated into modified\nboundary conditions for Maxwell's equations, the so-called mesoscopic boundary\nconditions. These modifications can in principle be implemeted in any Maxwell\nsolver, although the technicalities can be subtle and depend on the chosen\ncomputational approach. In this paper we show how to implement the mesoscopic\nboundary conditions in a boundary element method approach, based on a Galerkin\nscheme with Raviart-Thomas shape elements for the representation of the\ntangential electromagnetic fields at the boundary. We demonstrate that the\nresults of our simulations are in perfect agreement with Mie theory including\nFeibelman parameters, and that for typical simulation scenarios the\ncomputational overhead is usually small."
    },
    {
        "anchor": "Time-resolved single-particle x-ray scattering reveals electron-density\n  as coherent plasmonic-nanoparticle-oscillation source: Dynamics of optically-excited plasmonic nanoparticles are presently\nunderstood as a series of sequential scattering events, involving\nthermalization processes after pulsed optical excitation. One important step is\nthe initiation of nanoparticle breathing oscillations. According to established\nexperiments and models, these are caused by the statistical heat transfer from\nthermalized electrons to the lattice. An additional contribution by hot\nelectron pressure has to be included to account for phase mismatches that arise\nfrom the lack of experimental data on the breathing onset. We used optical\ntransient-absorption spectroscopy and time-resolved single-particle\nx-ray-diffractive imaging to access the excited electron system and lattice.\nThe time-resolved single-particle imaging data provided structural information\ndirectly on the onset of the breathing oscillation and confirmed the need for\nan additional excitation mechanism to thermal expansion, while the observed\nphase-dependence of the combined structural and optical data contrasted\nprevious studies. Therefore, we developed a new model that reproduces all our\nexperimental observations without using fit parameters. We identified\noptically-induced electron density gradients as the main driving source.",
        "positive": "Phonon-assisted tunneling through quantum dot systems connected to\n  Majorana bound states: We theoretically analyze phonon-assisted tunneling transport in a quantum dot\nside-connected to a Majorana bound state in a topological superconducting\nnanowire. We investigate the behavior of the current through the dot, for a\nrange of experimentally relevant parameters, in the presence of one long-wave\noptical phonon. We consider the current-gate voltage, the current-bias voltage,\nand the current-dot-Majorana coupling characteristics under the influence of\nthe electron-phonon coupling. In the absence of electron-phonon interaction,\nthe Majorana bound states suppress the current when the gate voltage matches\nthe Fermi level, but the increase of the bias voltage counteracts this effect.\nIn the presence of electron-phonon coupling, the current behaves similarly as a\nfunction of the renormalized gate voltage. As an added feature at large bias\nvoltages, it presents a dip or a plateau, depending on the size of dot-Majorana\ncoupling. Lastly, we show that the currents are most sensitive to, and depend\nnon-trivially on the parameters of the Majorana circuit element, in the regime\nof low temperatures combined with low voltages. Our results provide insights\ninto the complex physics of quantum dot devices used to probe Majorana bound\nstates."
    },
    {
        "anchor": "3D-imaging of Printed Nanostructured Networks using High-resolution\n  FIB-SEM Nanotomography: Networks of solution-processed nanomaterials are important for multiple\napplications in electronics, sensing and energy storage/generation. While it is\nknown that network morphology plays a dominant role in determining the physical\nproperties of printed networks, it remains difficult to quantify network\nstructure. Here, we utilise FIB-SEM nanotomography to characterise the\nmorphology of nanostructured networks. Nanometer-resolution 3D-images were\nobtained from printed networks of graphene nanosheets of various sizes, as well\nas networks of WS2 nanosheets, silver nanosheets and silver nanowires.\nImportant morphological characteristics, including network porosity,\ntortuosity, pore dimensions and nanosheet orientation were extracted and linked\nto network resistivity. By extending this technique to interrogate the\nstructure and interfaces within vertical printed heterostacks, we demonstrate\nthe potential of this technique for device characterisation and optimisation.",
        "positive": "Collinear scattering of photoexcited carriers in graphene: We propose an explicitly solvable model for collinear scattering of\nphotoexcited carriers in intrinsic graphene irradiated by monochromatic light.\nWe find that the collinear scattering rate is directly proportional to the\nphotocarrier energy and derive an analytic expression for the corresponding\nrelaxation time. The result agrees with the recent numerical prediction [Mihnev\net al. Nat. Commun. vol. 7, 11617 (2016)] and is able to describe the\nphotocarrier evolution at low energies, where scattering on optical phonons is\nstrongly suppressed."
    },
    {
        "anchor": "Photon assisted long-range tunneling: We analyze long-range transport through an ac driven triple quantum dot with\none single electron. An effective model is proposed for the analysis of\nphotoassisted cotunnel in order to account for the virtual processes which\ndominate the long-range transport, which takes place at n-photon resonances\nbetween the edge quantum dots. The AC field renormalizes the inter dot hopping,\nmodifying the levels hybridization. It results in a non trivial behavior of the\ncurrent with the frequency and intensity of the external ac field.",
        "positive": "Superfluid spin transport through antiferromagnetic insulators: A theoretical proposal for realizing and detecting spin supercurrent in an\nisotropic antiferromagnetic insulator is reported. Superfluid spin transport is\nachieved by inserting the antiferromagnet between two metallic reservoirs and\nestablishing a spin accumulation in one reservoir such that a spin bias is\napplied across the magnet. We consider a class of bipartite antiferromagnets\nwith Neel ground states, and temperatures well below the ordering temperature,\nwhere spin transport is mediated essentially by the condensate. Landau-Lifshitz\nand magneto-circuit theories are used to directly relate spin current in\ndifferent parts of the heterostructure to the spin-mixing conductances\ncharacterizing the antiferromagnet|metal interfaces and the antiferromagnet\nbulk damping parameters, quantities all obtainable from experiments. We study\nthe efficiency of spin angular-momentum transfer at an antiferromagnet|metal\ninterface by developing a microscopic scattering theory for the interface and\nextracting the spin-mixing conductance for a simple model. Within the model, a\nquantitative comparison between the spin-mixing conductances obtained for the\nantiferromagnet|metal and ferromagnet|metal interfaces is made."
    },
    {
        "anchor": "Signatures of Wigner Localization in Epitaxially Grown Nanowires: It was predicted by Wigner in 1934 that the electron gas will undergo a\ntransition to a crystallized state when its density is very low. Whereas\nsignificant progress has been made towards the detection of electronic Wigner\nstates, their clear and direct experimental verification still remains a\nchallenge. Here we address signatures of Wigner molecule formation in the\ntransport properties of InSb nanowire quantum dot systems, where a few\nelectrons may form localized states depending on the size of the dot (i.e. the\nelectron density). By a configuration interaction approach combined with an\nappropriate transport formalism, we are able to predict the transport\nproperties of these systems, in excellent agreement with experimental data. We\nidentify specific signatures of Wigner state formation, such as the strong\nsuppression of the antiferromagnetic coupling, and are able to detect the onset\nof Wigner localization, both experimentally and theoretically, by studying\ndifferent dot sizes.",
        "positive": "Antiferromagnetic Domain Wall Motion Induced by Spin Waves: Spin waves in antiferromagnets are linearly or circularly polarized.\nDepending on the polarization, traversing spin waves alter the staggered field\nin a qualitatively different way. We calculate the drift velocity of a moving\ndomain wall as a result of spin wave mediated forces, and show that the domain\nwall moves in opposite directions for linearly and circularly polarized waves.\nThe analytical results agree with a micromagnetics simulation of an\nantiferromagnetic domain wall driven by a localized and alternating magnetic\nfield."
    },
    {
        "anchor": "Application of Convolutional Neural Network to Quantum Percolation in\n  Topological Insulators: Quantum material phases such as the Anderson insulator, diffusive metal, and\nWeyl/Dirac semimetal as well as topological insulators show specific wave\nfunctions both in real and Fourier spaces. These features are well captured by\nconvolutional neural networks, and the phase diagrams have been obtained, where\nstandard methods are not applicable. One of these examples is the cases of\nrandom lattices such as quantum percolation. Here, we study the topological\ninsulators with random vacancies, namely, the quantum percolation in\ntopological insulators, by analyzing the wave functions via a convolutional\nneural network. The vacancies in topological insulators are especially\ninteresting since peculiar bound states are formed around the vacancies. We\nshow that only a few percent of vacancies are required for a topological phase\ntransition. The results are confirmed by independent calculations of\nlocalization length, density of states, and wave packet dynamics.",
        "positive": "Current-induced magnetization dynamics in single and double layer\n  magnetic nanopillars grown by molecular beam epitaxy: Molecular beam epitaxy is used to fabricate magnetic single and double layer\njunctions which are deposited in prefabricated nanostencil masks. For all Co |\nCu | Co double layer junctions we observe a stable intermediate resistance\nstate which can be reached by current starting from the parallel configuration\nof the respective ferromagnetic layers. The generation of spin waves is\ninvestigated at room temperature in the frequency domain by spectrum analysis,\ndemonstrating both in-plane and out-of-plane precessions of the magnetization\nof the free magnetic layer. Current-induced magnetization dynamics in magnetic\nsingle layer junctions of Cu | Co | Cu has been investigated in magnetic fields\nwhich are applied perpendicular to the magnetic layer. We find a hysteretic\nswitching in the current sweeps with resistance changes significantly larger\nthan the anisotropic magnetoresistance effect."
    },
    {
        "anchor": "Dynamical Kohn Anomaly in Surface Acoustic Wave Response in Quantum Hall\n  Systems Near $\u03bd= 1/2$: The dynamical analog of the Kohn Anomaly image of the Fermi Surface is\ndemonstrated for the response functions to the surface acoustic waves in\nQuantum Hall Systems near $\\nu = 1/2$. Kinks appear in the velocity shift\n$Delta s/s$ and attenuation coefficient $\\Gamma$. The effect is considerably\nenhanced under periodic modulation and should be observable.",
        "positive": "Magnetic hysteresis in nanostructures with thermally-controlled RKKY\n  coupling: Mechanisms of the recently demonstrated ex-situ thermal control of the\nindirect exchange coupling in magnetic multilayer are discussed for different\ndesigns of the spacer layer. Temperature-induced changes in the hysteresis of\nmagnetization are shown to be associated with different types of competing\ninterlayer exchange interactions. Theoretical analysis indicates that the\nmeasured step-like shape and hysteresis of the magnetization loops is due to\nlocal in-plane magnetic anisotropy of nano-crystallites within the strongly\nferromagnetic films. Comparison of the experiment and theory is used to\ncontrast the mechanisms of the magnetization switching based on the competition\nof (i) indirect (RKKY) and direct (non-RKKY) interlayer exchange interactions\nas well as (ii) indirect ferromagnetic and indirect antiferromagnetic (both of\nRKKY type) interlayer exchange."
    },
    {
        "anchor": "Coulomb impurities in graphene driven by ultrashort electromagnetic\n  pulses: Excitation, ionization, and pair creation: We provide a theory for electronic transitions induced by ultrashort\nelectromagnetic pulses in two-dimensional artificial relativistic atoms which\nare created by a charged impurity in a gapped graphene monolayer. Using a\nnon-perturbative sudden-perturbation approximation, we derive and discuss\nanalytical expressions for the probabilities for excitation, ionization and\nelectron-hole pair creation in this system.",
        "positive": "Magnetocaloric effect and nature of magnetic transition in nanoscale\n  Pr0.5Ca0.5MnO3: Systematic measurements pertinent to the magnetocaloric effect and nature of\nmagnetic transition around the transition temperature are performed in the 10\nnm Pr0.5Ca0.5MnO3 nanoparticles (PCMO10) . Maxwell relation is employed to\nestimate the change in magnetic entropy. At Curie temperature TC, 83.5 K, the\nchange in magnetic entropy discloses a typical variation with a value 0.57 J/kg\nK, and is found to be magnetic field dependent. From the area under the curve\nDelta S vs T, the refrigeration capacity is calculated at TC, 83.5 K and it is\nfound to be 7.01 J/kg. Arrott plots infer that due to the competition between\nthe ferromagnetic and anti ferromagnetic interactions, the magnetic phase\ntransition in PCMO10 is broadly spread over both in temperature as well as in\nmagnetic field coordinates. Upon tuning the particle size, size distribution,\nmorphology, and relative fraction of magnetic phases, it may be possible to\nenhance the magnetocalorific effect further in PCMO10."
    },
    {
        "anchor": "Resonance fluorescence in driven quantum dots: electron and photon\n  correlations: We study the counting statistics for electrons and photons being emitted from\na driven two level quantum dot. Our technique allows us to calculate their\nmutual correlations as well. We study different transport configurations by\ntuning the chemical potential of one of the leads to find that the electronic\nand photonic fluctuations can be externally manipulated by tuning the AC and\ntransport parameters. We also propose special configurations where\nelectron-photon correlation is maximal meaning that spontaneous emission of\nphotons with a well defined energy is regulated by single electron tunneling.\nInteresting features are also obtained for energy dependent tunneling.",
        "positive": "Progress Towards Opto-Electronic Characterization of Indium Phosphide\n  Nanowire Transistors at milli-Kelvin temperatures: In this paper we present our progress towards the opto-electronic\ncharacterization of indium phosphide (InP) nanowire transistors at milli-Kelvin\n(mK) temperatures. First, we have investigated the electronic transport of the\nInP nanowires by current-voltage (I-V) spectroscopy as a function of\ntemperature from 300 K down to 40 K. Second, we show the successful operation\nof a red light emitting diode (LED) at liquid-Helium (and base) temperature to\nbe used for opto-electronic device characterization."
    },
    {
        "anchor": "Quantum capacitance oscillations in graphene under crossed magnetic and\n  electric fields: Quantum oscillations of metallic systems at low temperatures is one of the\nkey rules to experimentally access their electronic properties, such as energy\nspectrum, scattering mechanisms, geometry of Fermi surface and many other\nfeatures. The importance of these knowledge is enormous, since from these a\nthorough understanding of anomalous Hall effect, thermopower and Nernst\ncoefficients, just to name a few, is possible; and from those knowledge, a\nplenty of applications arise as emerging technologies. In this direction, the\npresent contribution focus on a complete description of quantum capacitance\noscillations of monolayer and bilayer graphenes under crossed electric and\nmagnetic fields. We found a closed theoretical expression for the quantum\ncapacitance and highlight their amplitude, period and phase - important\nparameters to access the electronic properties of graphenes. These results open\ndoors for further experimental studies.",
        "positive": "Accumulative magnetic switching of ultra-high-density recording media by\n  circularly polarized light: Manipulation of the magnetization by external energies other than magnetic\nfield, such as spin-polarized current1-4, electric voltage5,6 and circularly\npolarized light7-11 gives a paradigm shift in magnetic nanodevices.\nMagnetization control of ferromagnetic materials only by circularly polarized\nlight has received increasing attention both as a fundamental probe of the\ninteractions of light and magnetism but also for future high-density magnetic\nrecording technologies. Here we show that for granular FePt films, designed for\nultrahigh-density recording, the optical magnetic switching by circularly\npolarized light is an accumulative effect from multiple optical pulses. We\nfurther show that deterministic switching of high anisotropy materials by the\ncombination of circularly polarized light and modest external magnetic fields,\nthus revealing a pathway towards technological implementation."
    },
    {
        "anchor": "Nonlocal optical generation of spin and charge currents on the surface\n  of magnetic insulators using total absorption and surface plasmons: We study the nonlocal spin and charge current generation in a finite metallic\nelement on the surface of magnetic insulators such as \\tcb{yttrium iron garnet}\ndue to the absorption of the magnetic surface plasmon (MSP). Whereas a surface\nplasmon is completely reflected by a metal, \\tcb{an} MSP \\tcb{can be} absorbed\n\\tcb{due to the absence of backward states}. The \\tcb{injection of} MSP\ngenerates a voltage in the longitudinal direction parallel to the wave vector,\n\\tcb{with the voltage} proportional to input power. If the metal is a\nferromagnet, a spin current can also be \\tcb{induced} in the longitudinal\ndirection. Our \\tcb{results provide a way to improve upon} integrated circuits\nof spintronics and spin wave logic devices.",
        "positive": "Detection of magnetic impurities using electron vortex beams: Electron microscopy stands out as electron waves providing higher spatial\nresolving power compared to their optical counterpart. Here we investigate\ntheoretically the interaction of twisted electrons generated in transmission\nelectron microscope (TEM) and magnetic impurity, in which the magnetic dipole\nmoment is taken as a demonstration element. In addition to the usual optical\nphase, the inhomogeneous vector potential generated by the magnetic dipole\nmoment makes additional contribution to the intrinsic orbital angular momentum\nof electrons, resulting in a Gouy phase shift. By interfering the outgoing\ntwisted electron beam with a reference Gaussian-cylindrical wave, one can\ndetermine the magnitude and orientation of magnetic dipole directly via the\nrotational and deformed interference pattern. The obtained results demonstrate\nthe usefulness of twisted electron beams for probing the atomic- and nanoscale\nmagnetism of impurity by TEM and the proposed model provides the conceptual\nbasis for future developments of the TEM method."
    },
    {
        "anchor": "Pseudo Electric Field and Pumping Valley Current in Graphene\n  Nano-bubbles: The extremely high pseudo-magnetic field emerging in strained graphene\nsuggests that an oscillating nano-deformation will induce a very high current\neven without electric bias. In this paper, we demonstrate the sub-terahertz\n(THz) dynamics of a valley-current and the corresponding charge pumping with a\nperiodically excited nano-bubble. We discuss the amplitude of the\npseudo-electric field and investigate the dependence of the pumped valley\ncurrent on the different parameters of the system. Finally, we report the\nsignature of extra-harmonics generation in the valley current that might lead\nto potential modern devices development operating in the nonlinear regime",
        "positive": "State-dependent Topological Invariants and Anomalous Bulk-Boundary\n  Correspondence in non-Hermitian Topological Systems: The breakdown of the bulk-boundary correspondence in non-Hermitian (NH)\ntopological systems is an open, controversial issue. In this paper, to resolve\nthis issue, we ask the following question: Can a (global) topological invariant\ncompletely describe the topological properties of a NH system as its Hermitian\ncounterpart? Our answer is no. One cannot use a global topological invariant\n(including non-Bloch topological invariant) to accurately characterize the\ntopological properties of the NH systems. Instead, there exist a new type of\ntopological invariants that are absence in its Hermitian counterpart -- the\nstate dependent topological invariants. With the help of the state-dependent\ntopological invariants, we develop a new topological theory for NH topological\nsystem beyond the general knowledge for usual Hermitian systems and obtain an\nexact formulation of the bulk-boundary correspondence, including\nstate-dependent phase diagram, state-dependent phase transition and anomalous\ntransport properties (spontaneous topological current). Therefore, these\nresults will help people to understand the exotic topological properties of\nvarious non-Hermitian systems."
    },
    {
        "anchor": "Off-axis electron holography for the direct visualization of\n  perpendicular shape anisotropy in nano-scale 3D magnetic random-access-memory\n  devices: Perpendicular shape anisotropy (PSA) and double magnetic tunnel junctions\n(DMTJ) offer practical solutions to downscale spin-transfer-torque Magnetic\nRandom-Access Memory (STT-MRAM) beyond 20 nm technology nodes, whilst retaining\ntheir thermal stability and reducing critical currents applied. However, as\nthese modern devices become smaller and three-dimensionally (3D) complex, our\nunderstanding of their functional magnetic behavior is often indirect, relying\non magnetoresistance measurements and micromagnetic modelling. In this paper,\nwe review recent work that was performed on these structures using a range of\nadvanced electron microscopy techniques, focusing on aspects specific to the 3D\nand nanoscale nature of such elements. We present the methodology for the\nsystematic transfer of individual SST-MRAM nano-pillars from large-scale arrays\nto image their magnetic configurations directly using off-axis electron\nholography. We show that improved phase sensitivity through stacking of\nelectron holograms can be used to image subtle variations in DMTJs and the\nthermal stability of < 20 nm PSA-STT-MRAM nano-pillars during in-situ heating.\nThe experimental practicalities, benefits and limits of using electron\nholography for analysis of MRAM devices are discussed, unlocking practical\npathways for direct imaging of the functional magnetic performance of these\nsystems with high spatial resolution and sensitivity.",
        "positive": "Radiative heat transfer as a Landauer-B\u00fcttiker problem: We study the radiative heat transfer between two semi-infinite half-spaces,\nbounded by conductive surfaces in contact with vacuum. This setup is\ninterpreted as a four-terminal mesoscopic transport problem. The slabs and\ninterfaces are viewed as bosonic reservoirs, coupled perfectly to a scattering\ncenter consisting of the two interfaces and vacuum. Using Rytov's fluctuational\nelectrodynamics and assuming Kirchhoff's circuital law, we calculate the heat\nflow in each bath. This allows for explicit evaluation of a conductance matrix,\nfrom which one readily verifies B\\\"{u}ttiker symmetry. Thus, radiative heat\ntransfer in layered media with conductive interfaces becomes a\nLandauer-B\\\"{u}ttiker transport problem."
    },
    {
        "anchor": "Bosonic Bott Index and Disorder-Induced Topological Transitions of\n  Magnons: We investigate the role of disorder on the various topological magnonic\nphases present in deformed honeycomb ferromagnets. To this end, we introduce a\nbosonic Bott index to characterize the topology of magnon spectra in finite,\ndisordered systems. The consistency between the Bott index and Chern number is\nnumerically established in the clean limit. We demonstrate that topologically\nprotected magnon edge states are robust to moderate disorder and, as\nanticipated, localized in the strong regime. We predict a disorder-driven\ntopological phase transition, a magnonic analog of the \"topological Anderson\ninsulator\" in electronic systems, where the disorder is responsible for the\nemergence of the nontrivial topology. Combining the results for the Bott index\nand transport properties, we show that bulk-boundary correspondence holds for\ndisordered topological magnons. Our results open the door for research on\ntopological magnonics as well as other bosonic excitations in finite and\ndisordered systems.",
        "positive": "Controlling Movement at Nanoscale: Curvature Driven Mechanotaxis: Locating and manipulating nano-sized objects to drive motion is a time and\neffort consuming task. Recent advances show that it is possible to generate\nmotion without direct intervention, by embedding the source of motion in the\nsystem configuration. In this work, we demonstrate an alternative manner to\ncontrollably displace nano-objects without external manipulation, by employing\nspiral-shaped carbon nanotube (CNT) and graphene nanoribbon structures (GNR).\nThe spiral shape contains smooth gradients of curvature, which lead to smooth\ngradients of bending energy. We show these gradients can drive nanoscillators.\nWe also carry out an energy analysis by approximating the carbon nanotube to a\nthin rod and discuss how torsional gradients can be used to drive motion. For\nthe nanoribbons, we also analyzed the role of layer orientation. Our results\nshow that motion is not sustainable for commensurate orientations, in which AB\nstacking occurs. For incommensurate orientations, friction almost vanishes, and\nin this instance, the motion can continue even if the driving forces are not\nvery high. This suggests that mild curvature gradients, which can already be\nfound in existing nanostructures, could provide mechanical stimuli to direct\nmotion."
    },
    {
        "anchor": "Nonlinear response of a ballistic graphene transistor with an ac-driven\n  gate: high harmonic generation and THz detection: We present results for time-dependent electron transport in a ballistic\ngraphene field-effect transistor with an ac-driven gate. Nonlinear response to\nthe ac drive is derived utilizing Floquet theory for scattering states in\ncombination with Landauer-B\\\"uttiker theory for transport. We identify two\nregimes that can be useful for applications: (i) low and (ii) high doping of\ngraphene under source and drain contacts, relative to the doping level in the\ngraphene channel, which in an experiment can be varied by a back gate. In both\nregimes, inelastic scattering induced by the ac drive can excite quasi-bound\nstates in the channel that leads to resonance promotion of higher order\nsidebands. Already for weak to intermediate ac drive strength, this leads to a\nsubstantial change in the direct current between source and drain. For strong\nac drive with frequency $\\Omega$, we compute the higher harmonics of\nfrequencies $n\\Omega$ ($n$ integer) in the source-drain conductance. In regime\n(ii), we show that particular harmonics (for instance $n=6$) can be selectively\nenhanced by tuning the doping level in the channel or by tuning the drive\nstrength. We propose that the device operated in the weak-drive regime can be\nused to detect THz radiation, while in the strong-drive regime it can be used\nas a frequency multiplier.",
        "positive": "Enhanced anomalous Nernst effect in disordered Dirac and Weyl materials: We analyze the thermoelectric response of Dirac and Weyl semimetals using the\nsemiclassical approach, focusing on the extrinsic contributions due to\nskew-scattering and side jump. Our results apply to linear response Nernst\neffect in ferromagnetic Dirac materials such as Fe$_3$Sn$_2$, Weyl semimetal\nCo$_3$Sn$_2$S$_2$ and to second order response of monolayer graphene on hBN\nwith trigonal warping. Our analysis indicates that the extrinsic contributions\ncan be a significant component of anomalous Nernst response and used to explain\nan enhanced thermoelectric response."
    },
    {
        "anchor": "Fingerprints of Majorana bound states in quantum-rings: In this work, we investigate a quantum-ring coupled to a topological\nsuperconductor, hosting Majorana bound states (MBSs). We study the MBSs effects\nover the spectrum and persistent current along the quantum-ring. To obtain\nphysical quantities, we employ the Green's function formalism. We found that\nthe presence of MBSs leads to dramatic changes in the quantum-ring spectrum by\ninducing particle-hole symmetry. On the other hand, we have obtained a\nsubstantial reduction of the persistent current in the strong coupling limit\nbetween ring and MBSs depending on the ring parity. These behaviors provide a\nmeasurable signature of MBSs. Our findings could be used as additional\ninformation on MBSs presence in these quantum systems.",
        "positive": "Transport signatures of topological superconductivity in a\n  proximity-coupled nanowire: We study the conductance of a junction between the normal and superconducting\nsegments of a nanowire, both of which are subjected to spin-orbit coupling and\nan external magnetic field. We directly compare the transport properties of the\nnanowire assuming two different models for the superconducting segment: one\nwhere we put superconductivity by hand into the wire, and one where\nsuperconductivity is induced through a tunneling junction with a bulk s-wave\nsuperconductor. While these two models are equivalent at low energies and at\nweak coupling between the nanowire and the superconductor, we show that there\nare several interesting qualitative differences away from these two limits. In\nparticular, the tunneling model introduces an additional conductance peak at\nthe energy corresponding to the bulk gap of the parent superconductor. By\nemploying a combination of analytical methods at zero temperature and numerical\nmethods at finite temperature, we show that the tunneling model of the\nproximity effect reproduces many more of the qualitative features that are seen\nexperimentally in such a nanowire system."
    },
    {
        "anchor": "Thermal conductance and thermoelectric figure of merit of C$_{60}$-based\n  single-molecule junctions: electrons, phonons, and photons: Motivated by recent experiments, we present here an ab initio study of the\nimpact of the phonon transport on the thermal conductance and thermoelectric\nfigure of merit of C$_{60}$-based single-molecule junctions. To be precise, we\ncombine density functional theory with nonequilibrium Green's function\ntechniques to compute these two quantities in junctions with either a C$_{60}$\nmonomer or a C$_{60}$ dimer connected to gold electrodes, taking into account\nthe contributions of both electrons and phonons. Our results show that for\nC$_{60}$ monomer junctions phonon transport plays a minor role in the thermal\nconductance and, in turn, in the figure of merit, which can reach relatively\nhigh values on the order of 0.1, depending on the contact geometry. At the\ncontrary, phonons completely dominate the thermal conductance in C$_{60}$ dimer\njunctions and strongly reduce the figure of merit as compared to monomer\njunctions. Thus, claims that by stacking C$_{60}$ molecules one could achieve\nhigh thermoelectric performance, which have been made without considering the\nphonon contribution, are not justified. Moreover, we analyze the relevance of\nnear-field thermal radiation for the figure of merit of these junctions within\nthe framework of fluctuational electrodynamics. We conclude that photon\ntunneling can be another detrimental factor for the thermoelectric performance,\nwhich has been overlooked so far in the field of molecular electronics. Our\nstudy illustrates the crucial roles that phonon transport and photon tunneling\ncan play when critically assessing the performance of molecular junctions as\npotential nanoscale thermoelectric devices.",
        "positive": "Spin Orbit coupling and Anomalous Josephson effect in Nanowires: A superconductor-semiconducting nanowire-superconductor heterostructure in\nthe presence of spin orbit coupling and magnetic field can support a\nsupercurrent even in the absence of phase difference between the\nsuperconducting electrodes. We investigate this phenomenon, the anomalous\nJosephson effect, employing a model capable of describing many bands in the\nnormal region. We discuss geometrical and symmetry conditions required to have\nfinite anomalous supercurrent and in particular we show that this phenomenon is\nenhanced when the Fermi level is located close to a band opening in the normal\nregion."
    },
    {
        "anchor": "Magnetic structure at zigzag edges of graphene bilayer ribbons: We study the edge magnetization of bilayer graphene ribbons with zigzag\nedges. The presence of flat edge-state bands at the Fermi energy of undoped\nbilayer, which gives rise to a strong peak in the density of states, makes\nbilayer ribbons magnetic at the edges even for very small on-site electronic\nrepulsion. Working with the Hubbard model in the Hartree Fock approximation we\nshow that the magnetic structure in bilayer ribbons with zigzag edges is\nferromagnetic along the edge, involving sites of the two layers, and\nantiferromagnetic between opposite edges. It is also shown that this magnetic\nstructure is a consequence of the nature of the edge states present in bilayer\nribbons with zigzag edges. Analogously to the monolayer case, edge site\nmagnetization as large as $m \\approx0.2 \\mu_{B}$ (per lattice site) even at\nsmall on-site Hubbard repulsion $U \\approx 0.3 {eV}$ is realized in nanometer\nwide bilayer ribbons.",
        "positive": "Surface effect on the wrinkling of an elastic sheet under tension: Wrinkling of stretched elastic sheets is widely observed, and the scaling\nrelations between the amplitude and wavelength of the wrinkles have been\nproposed by Cerda and Mahadevan. However, the surface effects should be taken\ninto account when the sheet is even thinner. The surface energy was considered\nin this work, and the discrepancies with the classical theory has been\ndiscussed. A dimensionless parameter has been proposed to represent the\nsize-dependence. A method of characterizing mechanical properties of thin film\nusing wrinkles considering surface effects has also been proposed."
    },
    {
        "anchor": "Nonlinear Transport, Dynamic Ordering, and Clustering for Driven\n  Skyrmions on Random Pinning: Using numerical simulations, we examine the nonlinear dynamics of skyrmions\ndriven over random pinning. For weak pinning, the skyrmions depin elastically,\nretaining sixfold ordering; however, at the onset of motion there is a dip in\nthe magnitude of the structure factor peaks due to a decrease in positional\nordering, indicating that the depinning transition can be detected using the\nstructure factor even within the elastic depinning regime. At higher drives the\nmoving skyrmion lattice regains full ordering. For increasing pinning strength,\nwe find a transition from elastic to plastic depinning that is accompanied by a\nsharp increase in the depinning threshold due to the proliferation of\ntopological defects, similar to the peak effect found at the elastic to plastic\ndepinning transition in superconducting vortex systems. For strong pinning and\nstrong Magnus force, the skyrmions in the moving phase can form a strongly\nclustered or phase separated state with highly modulated skyrmion density,\nsimilar to that recently observed in continuum-based simulations for strong\ndisorder. As the Magnus force is decreased, the density phase separated state\ncrosses over to a dynamically phase separated state with uniform density but\nwith flow localized in bands of motion, while in the strongly damped limit,\nboth types of phase separated states are lost. In the strong pinning limit, we\nfind highly nonlinear velocity-force curves in the transverse and longitudinal\ndirections, along with distinct regions of negative differential conductivity\nin the plastic flow regime. The negative differential conductivity is absent in\nthe overdamped limit. The Magnus force is responsible for both the negative\ndifferential conductivity and the clustering effects, since it causes faster\nmoving skyrmions to partially rotate around slower moving or pinned skyrmions.",
        "positive": "Effects of photon field on heat transport through a quantum wire\n  attached to leads: We theoretically investigate photo-thermoelectric transport through a quantum\nwire in a photon cavity coupled to electron reservoirs with different\ntemperatures. Our approach, based on a quantum master equation, allows us to\ninvestigate the influence of a quantized photon field on the heat current and\nthermoelectric transport in the system. We find that the heat current through\nthe quantum wire is influenced by the photon field resulting in a negative heat\ncurrent in certain cases. The characteristics of the transport are studied by\ntuning the ratio, $\\hbar\\omega_{\\gamma} / k_{\\rm B} \\Delta T$, between the\nphoton energy, $\\hbar\\omega_{\\gamma}$, and the thermal energy, $k_{\\rm B}\n\\Delta T$. The thermoelectric transport is enhanced by the cavity photons when\n$k_{\\rm B} \\Delta T > \\hbar\\omega_{\\gamma}$. By contrast, if $k_{\\rm B} \\Delta\nT < \\hbar\\omega_{\\gamma}$, the photon field is dominant and a suppression in\nthe thermoelectric transport can be found in the case when the cavity-photon\nfield is close to a resonance with the two lowest one-electron states in the\nsystem. Our approach points to a new technique to amplify thermoelectric\ncurrent in nano-devices."
    },
    {
        "anchor": "Thermoelectric transport properties in graphene connected molecular\n  junctions: We study the electronic contribution to the main thermoelectric properties of\na molecular junction consisting of a single quantum dot coupled to graphene\nexternal leads. The system electrical conductivity (G), Seebeck coefficient\n($S$), and the thermal conductivity ($\\kappa$), are numerically calculated\nbased on a Green's function formalism that includes contributions up to the\nHartree-Fock level. We consider the system leads to be made either of pure or\ngapped-graphene. To describe the free electrons in the gapped-graphene\nelectrodes we used two possible scenarios, the massive gap scenario, and the\nmassless gap scenario, respectively. In all cases, the Fano effect is\nresponsible for a strong violation of the Wiedemann-Franz law and we found a\nsubstantial increase of the system figure of merit $ZT$ due to a drastic\nreduction of the system thermal coefficient. In the case of gapped-graphene\nelectrodes, the system figure of merit presents a maximum at an optimal value\nof the energy gap of the order of $\\Delta/D\\sim$ 0.002 (massive gap scenario)\nand $\\Delta/D\\sim$ 0.0026 (massless gap scenario). Additionally, for all cases,\nthe system figure of merit is temperature dependent.",
        "positive": "Two level anti-crossings high up in the single-particle energy spectrum\n  of a quantum dot: We study the evolution with magnetic field of the single-particle energy\nlevels high up in the energy spectrum of one dot as probed by the ground state\nof the adjacent dot in a weakly coupled vertical quantum dot molecule. We find\nthat the observed spectrum is generally well accounted for by the calculated\nspectrum for a two-dimensional elliptical parabolic confining potential, except\nin several regions where two or more single-particle levels approach each\nother. We focus on two two-level crossing regions which show unexpected\nanti-crossing behavior and contrasting current dependences. Within a simple\ncoherent level mixing picture, we can model the current carried through the\ncoupled states of the probed dot provided the intrinsic variation with magnetic\nfield of the current through the states (as if they were uncoupled) is\naccounted for by an appropriate interpolation scheme."
    },
    {
        "anchor": "Effect of interactions on quantum-limited detectors: We consider the effect of electron-electron interactions on a voltage biased\nquantum point contact in the tunneling regime used as a detector of a nearby\nqubit. We model the leads of the quantum point contact as Luttinger liquids,\nincorporate the effects of finite temperature and analyze the detection-induced\ndecoherence rate and the detector efficiency, $Q$. We find that interactions\ngenerically reduce the induced decoherence along with the detector's\nefficiency, and strongly affect the relative strength of the decoherence\ninduced by tunneling and that induced by interactions with the local density.\nWith increasing interaction strength, the regime of quantum-limited detection\n($Q=1$) is shifted to increasingly lower temperatures or higher bias voltages\nrespectively. For small to moderate interaction strengths, $Q$ is a\nmonotonously decreasing function of temperature as in the non-interacting case.\nSurprisingly, for sufficiently strong interactions we identify an intermediate\ntemperature regime where the efficiency of the detector increases with rising\ntemperature.",
        "positive": "Assessment on Thermal Transport Properties of Group-III Nitrides: A\n  Classical Molecular Dynamics Study with Transferable Tersoff Type\n  Inter-atomic Potentials: In this study, by means of classical molecular dynamics simulations, we\ninvestigated the thermal transport properties of hexagonal single-layer,\nzinc-blend and wurtzite phases of BN, AlN, and GaN crystals, which are very\npromising for the application and design of high-quality electronic devices.\nWith this in mind, we generated fully transferable Tersoff-type empirical\ninter-atomic potential parameter sets by utilizing an optimization procedure\nbased on particle swarm optimization. The predicted thermal properties as well\nas the structural, mechanical and vibrational properties of all materials are\nin very good agreement with existing experimental and first-principles data.\nThe impact of isotopes on thermal transport is also investigated and between\n$\\sim$10 and 50\\% reduction in phonon thermal transport with random isotope\ndistribution is observed in BN and GaN crystals. Our investigation distinctly\nshows that the generated parameter sets are fully transferable and very useful\nin exploring the thermal properties of systems containing these nitrides."
    },
    {
        "anchor": "Nanoscale roughness and morphology affect the IsoElectric Point of\n  titania surfaces: We report on the systematic investigation of the role of surface nanoscale\nroughness and morphology on the charging behaviour of nanostructured titania\n(TiO2) surfaces in aqueous solutions. IsoElectric Points (IEPs) of surfaces\nhave been characterized by direct measurement of the electrostatic double layer\ninteractions between titania surfaces and the micrometer-sized spherical silica\nprobe of an atomic force microscope in NaCl aqueous electrolyte. The use of a\ncolloidal probe provides well-defined interaction geometry and allows\neffectively probing the overall effect of nanoscale morphology. By using\nsupersonic cluster beam deposition to fabricate nanostructured titania films,\nwe achieved a quantitative control over the surface morphological parameters.\nWe performed a systematical exploration of the electrical double layer\nproperties in different interaction regimes characterized by different ratios\nof characteristic nanometric lengths of the system: the surface rms roughness\nRq, the correlation length {\\xi} and the Debye length {\\lambda}D. We observed a\nremarkable reduction by several pH units of IEP on rough nanostructured\nsurfaces, with respect to flat crystalline rutile TiO2. In order to explain the\nobserved behavior of IEP, we consider the roughness-induced self-overlap of the\nelectrical double layers as a potential source of deviation from the trend\nexpected for flat surfaces.",
        "positive": "Terahertz Induced Photoconductivity of 2D Electron System in HEMT at Low\n  Magnetic Field: A few results of our study of two-dimensional electron system (2DES) in low\nmagnetic fields in GaAs/GaAlAs heterostructures by cyclotron resonance (CR) and\nphotoconductivity techniques are presented. We have first discovered\n\"CR-vanishing effect\"in 2DES as well-defined crevasse on CR line in low\nmagnetic fields, when Hall resistance is not quantized. \"CR-vanishing effect\"\nindicates vanishing longitudinal resistance & conductivity in these magnetic\nfields. Observed \"CR-vanishing effect\" demonstrates new correlated state of\nelectrons in 2DES."
    },
    {
        "anchor": "Quantum Hall stripes in high-density GaAs/AlGaAs quantum wells: We report on quantum Hall stripes (QHSs) formed in higher Landau levels of\nGaAs/AlGaAs quantum wells with high carrier density ($n_e > 4 \\times 10^{11}$\ncm$^{-2}$) which is expected to favor QHS orientation along unconventional\n$\\left < 1\\bar{1}0 \\right >$ crystal axis and along the in-plane magnetic field\n$B_{||}$. Surprisingly, we find that at $B_{||} = 0$ QHSs in our samples are\naligned along $\\left < 110 \\right >$ direction and can be reoriented only\nperpendicular to $B_{||}$. These findings suggest that high density alone is\nnot a decisive factor for either abnormal native QHS orientation or alignment\nwith respect to $B_{||}$, while quantum confinement of the 2DEG likely plays an\nimportant role.",
        "positive": "Quantum Inductance and High Frequency Oscillators in Graphene\n  Nanoribbons: Here we investigate high frequency AC transport through narrow graphene\nnanoribbons with topgate potentials that form a localized quantum dot. We show\nthat as a consequence of the finite dwell time of an electron inside the\nquantum dot (QD), the QD behaves like a classical inductor at sufficiently high\nfrequencies \\omega\\gtrsim50 GHz. When the geometric capacitance of the topgate\nand the quantum capacitance of the nanoribbon are accounted for, the admittance\nof the device behaves like a classical serial RLC circuit with resonant\nfrequencies \\omega\\sim100-900 GHz and Q-factors greater than 10^{6}. These\nresults indicate that graphene nanoribbons can serve as all-electronic\nultra-high frequency oscillators and filters thereby extending the reach of\nhigh frequency electronics into new domains."
    },
    {
        "anchor": "Ground-state of fractional and integral quantum Hall systems at $\u03bd\n  \\leq 1$ and it excitations: Many-body variational ground-state wave function of two-dimensional electron\nsystem (2DES), localized in the main strip (MS)$L_{x}^{\\square} \\times L_{y}$\nof the finite width $L_{x}^{\\square}=\\sqrt{2 \\pi m} \\ell_{0}$ (and the periodic\nboundary condition (PBC) imposed along $x-$direction), is presented at the\nfractional and the integral filling factors $\\nu=1/m$ for two different ion\nbackgrounds: microscopical uniform ion background (UIB) and classical ion\njellium background (IJB); $\\ell_{0}$ is the magnetic length, $m=2\\ell+1$ and\n$\\ell=0, 1, 2,...$. It is shown that the ground-state and the lowest\nexcited-state can correspond to partial crystal-like correlation order among\n$N$ electrons of the main region (MR) $L_{x} \\times L_{y}$; then the study of\n2DES of $N$ electrons within MR is exactly reduced to the treatment of 2DES of\n$\\tilde{N}=N L_{x}^{\\square}/L_{x}$ electrons localized within MS, with PBC\nalong $x$. The ground-state manifests the broken symmetry liquid-crystal state\nwith 2DES density that is periodic along the $y-$ direction, with the period\n$L_{x}^{\\square}/m$, and independent of $x$. For IJB, at $m=3, 5$, the\nground-state has essentially lower energy per electron than the Laughlin,\nuniform liquid, ground-state (the Laughlin model uses IJB); the same holds at\n$m=1$. Obtained compound exciton and compound spin-exciton states show finite\nexcitation gaps. The excited compound electron (hole) is composed, within MS,\nfrom $m$ strongly correlated quasielectrons (quasiholes) of the charge $e/m$\n($-e/m$. Quantized Hall conductance $\\sigma_{H}=e^{2}/(2 m \\pi \\hbar)$ is\nobtained. The theory is in good agreement with experiments.",
        "positive": "Nonsymmorphic symmetry-required band crossings in topological semimetals: We show that for two-band systems nonsymmorphic symmetries may enforce the\nexistence of band crossings in the bulk, which realize Fermi surfaces of\nreduced dimensionality. We find that these unavoidable crossings originate from\nthe momentum dependence of the nonsymmorphic symmetry, which puts strong\nrestrictions on the global structure of the band configurations. Three\ndifferent types of nonsymmorphic symmetries are considered: (i) a unitary\nnonsymmorphic symmetry, (ii) a nonsymmorphic magnetic symmetry, and (iii) a\nnonsymmorphic symmetry combined with inversion. For nonsymmorphic symmetries of\nthe latter two types, the band crossings are located at high-symmetry points of\nthe Brillouin zone, with their exact positions being determined by the algebra\nof the symmetry operators. To characterize these band degeneracies we introduce\na \\emph{global} topological charge and show that it is of $\\mathbb{Z}_2$ type,\nwhich is in contrast to the \\emph{local} topological charge of Fermi points in,\nsay, Weyl semimetals. To illustrate these concepts, we discuss the $\\pi$-flux\nstate as well as the SSH model at its critical point and show that these two\nmodels fit nicely into our general framework of nonsymmorphic two-band systems."
    },
    {
        "anchor": "Low-damping sub-10-nm thin films of lutetium iron garnet grown by\n  molecular-beam epitaxy: We analyze the structural and magnetic characteristics of (111)-oriented\nlutetium iron garnet (Lu$_3$Fe$_5$O$_{12}$) films grown by molecular-beam\nepitaxy, for films as thin as 2.8 nm. Thickness-dependent measurements of the\nin- and out-of-plane ferromagnetic resonance allow us to quantify the effects\nof two-magnon scattering, along with the surface anisotropy and the saturation\nmagnetization. We achieve effective damping coefficients of $11.1(9) \\times\n10^{-4}$ for 5.3 nm films and $32(3) \\times 10^{-4}$ for 2.8 nm films, among\nthe lowest values reported to date for any insulating ferrimagnetic sample of\ncomparable thickness.",
        "positive": "Spin-density and charge-density excitations in quantum wires: We study an interacting electron gas in a quantum wire within the\nHartree-Fock random phase approximation. Vertex corrections to the electron\nspin polarizability due to the electronic exchange interaction are important\ngiving rise to spin-density excitations (SDE) with large oscillator strength\nshifted to lower energies with respect to single-particle states. The energy of\nintersubband SDE oscillates with the number of subbands occupied and has a\nminimum when a subband energy is close to the chemical potential. Intrasubband\nSDE have a linear dispersion at small wave-vectors. The corresponding sound\nvelocity is reduced with respect to the Fermi velocity due to exchange\ninteraction within the occupied subbands and exchange screening caused by\nvirtual transitions to upper subbands. For intersubband and intrasubband\ncharge-density excitations (CDE) vertex corrections are of less importance. For\nonly a single subband occupied the screening of CDE and SDE in the\nTomonaga-Luttinger model due to virtual transitions to upper subband is\nstudied, where the virtual transitions are treated within the Hartree-Fock\napproximation. The calculations are in good qualitative agreement with\nexperiments."
    },
    {
        "anchor": "Electromagnetic absorption of a pinned Wigner crystal at finite\n  temperatures: We investigate the microwave absorption of a pinned, two-dimensional Wigner\ncrystal in a strong magnetic field at finite temperatures. Using a model of a\nuniform commensurate pinning potential, we analyze thermal broadening of the\nelectromagnetic absorption resonance. Surprisingly, we find that the pinning\nresonance peak should remain sharp even when the temperature is comparable or\ngreater than the peak frequency. This result agrees qualitatively with recent\nexperimental observations of the ac conductivity in two-dimensional hole\nsystems in a magnetically induced insulating state. It is shown, in analogy\nwith Kohn's theorem, that the electron-electron interaction does not affect the\nresponse of a harmonically pinned Wigner crystal to a spatially uniform\nexternal field at any temperature. We thus focus on anharmonicity in the\npinning potential as a source of broadening. Using a 1/N expansion technique,\nwe show that the broadening is introduced through the self-energy corrections\nto the magnetophonon Green's functions.",
        "positive": "Path integral Monte Carlo simulation of charged particles in traps: This chapter is devoted to the computation of equilibrium (thermodynamic)\nproperties of quantum systems. In particular, we will be interested in the\nsituation where the interaction between particles is so strong that it cannot\nbe treated as a small perturbation. For weakly coupled systems many efficient\ntheoretical and computational techniques do exist. However, for strongly\ninteracting systems such as nonideal gases or plasmas, strongly correlated\nelectrons and so on, perturbation methods fail and alternative approaches are\nneeded. Among them, an extremely successful one is the Monte Carlo (MC) method\nwhich we are going to consider in this chapter."
    },
    {
        "anchor": "T-duality and the bulk-boundary correspondence: String-theoretic T-duality can be exploited to simplify some features of the\nbulk-boundary correspondence in condensed matter theory. This paper surveys how\nT-duality links position and momentum space pictures of that correspondence.",
        "positive": "Long range electron transfer across $\u03c0$-conjugated systems: role of\n  electron correlations: We consider a prototype polyene chain: donor-$\\pi$(bridge)-acceptor. The\ndistance between the donor and the acceptor is varied by increasing the number\nof bridged atoms and rate of electron transfer, k$_{et}$ is studied for a\nseries of different donors, D=NH$_2$, SH, OH, and a fixed acceptor, A=NO$_2$.\nWe observe a large k$_{et}$ even at a very large D-A separation of $\\sim$ 45\n$\\AA$, unexpected from the well-known and standard theories like the Forster\ntheory. Such a long range electron transfer is due to the strong\nelectron-electron interactions in the bridged orbitals that result in\ndeconfinment of electrons in donor orbitals. Calculations at various levels:\nsemi-empirical and many-body exact, have been performed to accurately account\nfor such correlations."
    },
    {
        "anchor": "Gauge invariance and Ward identities in nonlinear response theory: We present a formal analysis of nonlinear response functions in terms of\ncorrelation functions in real- and imaginary-time domains. In particular, we\nshow that causal nonlinear response functions, expressed in terms of nested\ncommutators in real time, can be obtained from the analytic continuation of\ntime-ordered response functions, which are more easily amenable to diagrammatic\ncalculation. This generalizes the well-known result of linear response theory.\nWe then use gauge invariance arguments to derive exact relations between\nsecond-order response functions in density and current channels. These\nidentities, which are non-perturbative in the strength of inter-particle\ninteractions, allow us to establish exact connections between nonlinear optics\ncalculations done in different electromagnetic gauges.",
        "positive": "Chemical Gating of a Weak Topological Insulator: Bi14Rh3I9: The compound Bi14Rh3I9 has recently been suggested as a weak\nthree-dimensional topological insulator on the basis of angle-resolved\nphotoemission and scanning-tunneling experiments in combination with density\nfunctional (DF) electronic structure calculations. These methods unanimously\nsupport the topological character of the headline compound, but a compelling\nconfirmation could only be obtained by dedicated transport experiments. The\nlatter, however, are biased by an intrinsic n-doping of the materials surface\ndue to its polarity. Electronic reconstruction of the polar surface shifts the\ntopological gap below the Fermi energy, which would also prevent any future\ndevice application. Here, we report the results of DF slab calculations for\nchemically gated and counter-doped surfaces of Bi14Rh3I9. We demonstrate that\nboth methods can be used to compensate the surface polarity without closing the\nelectronic gap."
    },
    {
        "anchor": "Quantum Metrology Triangle Experiments: A Status Review: Quantum Metrology Triangle experiments combine three quantum electrical\neffects (the Josephson effect, the quantum Hall effect and the single-electron\ntransport effect) used in metrology. These experiments allow important\nfundamental consistency tests on the validity of commonly assumed relations\nbetween fundamental constants of nature and the quantum electrical effects.\nThis paper reviews the history, results and the present status and perspectives\nof Quantum Metrology Triangle experiments. It also reflects on the possible\nimplications of results for the knowledge on fundamental constants and the\nquantum electrical effects.",
        "positive": "Electrically Tunable Optical Absorption in a Graphene-based Salisbury\n  Screen: We demonstrate a graphene-based Salisbury screen consisting of a single layer\nof graphene placed in close proximity to a gold back reflector. The light\nabsorption in the screen can be actively tuned by electrically gating the\ncarrier density in the graphene layer with an ionic liquid/gel. The screen was\ndesigned to achieve maximum absorption at a target wavelength of 3.2 micrometer\nby using a 600 nm-thick, non-absorbing silica spacer layer. Spectroscopic\nreflectance measurements were performed in-situ as a function of gate bias. The\nchanges in the reflectance spectra were analyzed using a Fresnel based transfer\nmatrix model in which graphene was treated as an infinitesimally thin sheet\nwith conductivity given by the Kubo formula. Temporal coupled mode theory was\nemployed to analyze and intuitively understand the observed absorption changes\nin the Salisbury screen. We achieved ~ 6 % change in the optical absorption of\ngraphene by tuning the applied gate bias from 0.8 V to 2.6 V, where 0.8 V\ncorresponds to graphene's charge neutrality point."
    },
    {
        "anchor": "Photonic analog of graphene model and its extension -- Dirac cone,\n  symmetry, and edge states --: This paper presents a theoretical analysis on bulk and edge states in\nhoneycomb lattice photonic crystals with and without time-reversal and/or\nspace-inversion symmetries. Multiple Dirac cones are found in the photonic band\nstructure and the mass gaps are controllable via symmetry breaking. The zigzag\nand armchair edges of the photonic crystals can support novel edge states that\nreflect the symmetries of the photonic crystals. The dispersion relation and\nthe field configuration of the edge states are analyzed in detail in comparison\nto electronic edge states. Leakage of the edge states to free space is inherent\nin photonic systems and is fully taken into account in the analysis. A\ntopological relation between bulk and edge, which is analogous to that found in\nquantum Hall systems, is also verified.",
        "positive": "Deformation of a N\u00e9el-type Skyrmion in a Weak Inhomogeneous Magnetic\n  Field: Magnetization Ansatz and Interaction with a Pearl Vortex: In this work, we develop a theory of (meta)stable states of N\\'eel-type\nskyrmions in weak nonuniform magnetic fields. We claim an Ansatz for modeling\nthe non-symmetric magnetization that can be implied for both analytics and\nnumerical simulations. Our theory accounts for changes in the size of skyrmion\nparameters and also includes deformations from the centrally symmetric shape.\nThe ansatz streamlines the analytic calculation of the skyrmion free energy,\nenhancing the efficiency of the minimizing process. Performing the minimization\nin two stages, one can find all the minima, global and local, of the free\nenergy, discovering the stable and metastable states. We apply the developed\nmethodology to investigate the (meta)stable configurations of skyrmions\ninfluenced by the stray field of a Pearl vortex. Our study reveals the\ndependence of skyrmion spatial parameters on the vortex field effective\nstrength and presents a phase diagram identifying regions where metastable\nconfigurations are predicted. Corroborated by micromagnetic simulations, our\nfindings offer a detailed perspective on the interaction between magnetic\nskyrmions and superconducting vortices."
    },
    {
        "anchor": "Phonon Dispersion in Chiral Single Wall Carbon Nanotubes: The phonon dispersion of chiral single wall carbon nanotubes has been\nobtained from $6\\times 6$ dyanimic matrix. The present manuscript is the\nextension of G. D. Mahan and Gun Sang Jeon's work on armchair and zigzag\nnanotubes. [see P. R. B., {\\bf 70}, 075405 (2004)]. We use spring and mass\nmodel with the proper phonon potential suggested by \\cite{M2}. We can calculate\nthe dispersion of single wall carbon nanotubes near $\\Gamma$ point with\narbitrary chirality. The results are compatible with Mahan et. al's results for\narmchair and zigzag SWNTs.",
        "positive": "Minimal-excitation single-particle emitters: A comparison of charge and\n  energy transport properties: We investigate different types of time-dependently driven single-particle\nsources whose common feature is that they produce pulses of integer charge and\nminimally excite the Fermi sea. These sources are: a slowly driven mesoscopic\ncapacitor, a Lorentzian-shaped time-dependent bias voltage, and a local\ngate-voltage modulation of a quantum Hall edge state. They differ by their\nspecific driving protocols, e.g., they have a pure ac driving or a driving with\na dc component. In addition, only in the first of these setups, strong\nconfinement leading to a discrete energy spectrum of the conductor, is\nexploited for the single-particle emission. Here, we study if and how these\nbasic differences impact transport properties. Specifically, we address time-\nand energy-resolved charge and energy currents, as well as their zero-frequency\ncorrelators (charge-, energy- and mixed noise), as they are frequently used to\ncharacterize experiments in quantum optics with electrons. Beyond disparities\ndue to a different number and polarity of particles emitted per period, we in\nparticular identify differences in the impact, which temperature has on the\nobservables for sources with and without energy-dependent scattering\nproperties. We trace back these characteristics to a small set of relevant\nparameter ratios."
    },
    {
        "anchor": "Boundary Field Theory Approach to the Renormalization of SQUID Devices: We show that the quantum properties of some Josephson SQUID devices are\ndescribed by a boundary sine Gordon model. Our approach naturally describes\nmulti-junction SQUID devices and, when applied to a single junction SQUID (the\nrf-SQUID), it reproduces the known results of Glazman and Hekking. We provide a\ndetailed analysis of the regimes accessible to an rf-SQUID and to a\ntwo-Josephson junction SQUID device (the dc-SQUID). We then compute the normal\ncomponent of the current-response of a SQUID device to an externally applied\nvoltage and show that the equation describing the current-voltage\ncharacteristic function reduces to well-known results when the infrared cutoff\nis suitably chosen. Our approach helps in establishing new and interesting\nconnections between superconducting devices, quantum brownian motion, fermionic\nquantum wires and, more generally, quantum impurity problems.",
        "positive": "Longitudinal and spin-Hall conductance of a two-dimensional Rashba\n  system with arbitrary disorder: We calculate the longitudinal and spin-Hall conductances in four-lead bridges\nwith Rashba - Dresselhaus spin-orbit interactions. Numerical results are\nobtained both within Landauer-Buttiker formalism and by the direct evaluation\nof the Kubo formula. The microscopic Hamiltonian is obtained in the\ntight-binding approximation in terms of the neareast-neighbor hopping integral\n$t$, the Rashba spin-orbit coupling $V_R$, the Dresselhaus spin-orbit coupling\n$V_D$ and an Anderson-like, on-site disorder energy strength $W$. We reconfirm\nthat below a critical disorder threshold, the spin-Hall effect is present.\nFurther, we study the effect on the two conductivities of the Fermi energy,\nRashba/Dresselhaus coefficient ratio, and system size."
    },
    {
        "anchor": "Three-quarter Dirac points, Landau levels and magnetization in\n  $\u03b1$-(BEDT-TTF)$_2$I$_3$: The energies as a function of the magnetic field ($H$) and the pressure are\nstudied theoretically in the tight-binding model for the two-dimensional\norganic conductor,\n  $\\alpha$-(BEDT-TTF)$_2$I$_3$, in which massless Dirac fermions are realized.\nThe effects of the uniaxial pressure ($P$) are studied by using the\npressure-dependent hopping parameters. The system is semi-metallic with the\nsame area of an electron pocket and a hole pocket at $P < 3.0$~kbar, where the\nenergies $(\\varepsilon_{\\rm D}^0$) at the Dirac points locate below the Fermi\nenergy $(\\varepsilon_{\\rm F}^0$) when $H=0$. We find that at $P=2.3$~kbar the\nDirac cones are critically tilted. In that case a new type of band crossing\noccurs at \"three-quarter\"-Dirac points, i.e., the dispersion is quadratic in\none direction and linear in the other three directions. We obtain new\nmagnetic-field-dependences of the Landau levels $(\\varepsilon_n)$;\n$\\varepsilon_n-\\varepsilon^0_{\\textrm{D}} \\propto (n H)^{4/5}$ at $P=2.3$~kbar\n(\"three-quarter\"-Dirac points) and $|\\varepsilon_n-\\varepsilon_{\\rm F}^0|\n\\propto (n H)^2$ at $P=3.0$~kbar (the critical pressure for the semi-metallic\nstate). We also study the magnetization as a function of the inverse magnetic\nfield. We obtain two types of quantum oscillations. One is the usual de Haas\nvan Alphen (dHvA) oscillation, and the other is the unusual dHvA-like\noscillation which is seen even in the system without the Fermi surface.",
        "positive": "Assessing the role of quantum effects in 2D heterophase MoTe$_2$ field\n  effect transistors: The two-dimensional transition metal dichalcogenides (TMDs) have been\nproposed as candidates for the channel material in future field effect\ntransistor designs. The heterophase design which utilizes the metallic T- or T'\nphase of the TMD as contacts to the semiconducting H phase channel has shown\npromising results in terms of bringing down the contact resistance of the\ndevice. In this work, we use ab-initio calculations to demonstrate how\natomic-scale and quantum effects influence the ballistic transport properties\nin such heterophase transistors with channel lengths up to 20 nm. We\ninvestigate how the charge transfer depends on the carrier density both in T'-H\nMoTe$_2$ Schottky contacts and planar T'-H-T' MoTe$_2$ transistors. We find\nthat the size of the Schottky barrier and the charge transfer is dominated by\nthe local atomic arrangements at the interface and the doping level.\nFurthermore, two types of quantum states have a large influence on the charge\ntransport; interface states and standing waves in the semiconductor due to\nquantum confinement. We find that the latter can be associated with rises in\nthe current by more than an order of magnitude due to resonant tunneling. Our\nresults demonstrate the quantum mechanical nature of these 2D transistors and\nhighlight several challenges and possible solutions for achieving a competitive\nperformance of such devices."
    },
    {
        "anchor": "Simulations of metastable states near the apex of a force microscope tip\n  interacting with an ionic crystalline surface: Atoms or pairs of ions picked up by probe tips used in dynamic force\nmicroscopy (DFM) can be strongly displaced and even hop discontinuously upon\napproach to the sample surface. The energy barriers for some of those hops are\nof the right order of magnitude to explain the rise in energy dissipation\ncommonly observed in DFM measurements at room temperature. The systematic\ncomputations reported here can explain the infrequent jumps and very low\naverage energy dissipation observed low temperature in a previous DFM study on\na KBr(001) sample. Close to the surface we indeed find new states separated by\nsmall energy barriers which account for those phenomena. These energy barriers\nstrongly depend on details of the atomic arrangement in the vicinity of the tip\napex.",
        "positive": "Impact of $\\mathcal{T}$-symmetry on spin decoherence and control in a\n  synthetic spin-orbit field: The electrical control of a spin qubit in a quantum dot relies on spin-orbit\ncoupling (SOC), which could be either intrinsic to the underlying crystal\nlattice or heterostructure, or extrinsic via, for example, a micro-magnet. Here\nwe show that a key difference between the intrinsic SOC and the synthetic SOC\nintroduced by a micro-magnet is their symmetry under time reversal.\nSpecifically, the time-reversal symmetry ($\\mathcal{T}$-symmetry) of the\nintrinsic SOC leads to not only the traditional van Vleck cancellation known\nfor spin relaxation, but also vanishing spin dephasing to the lowest order of\nSOC, which we term as \"longitudinal spin-orbit field cancellation\". On the\nother hand, the synthetic SOC from a micro-magnet breaks the\n$\\mathcal{T}$-symmetry, therefore eliminates both the \"van Vleck cancellation\"\nand the \"longitudinal spin-orbit field cancellation\". In other words, the\neffective field $\\vec\\Omega$ experienced by the spin qubit does not depend on\nthe quantization magnetic field anymore, and a longitudinal component is\nallowed for $\\vec\\Omega$ to the first order of SOC. Consequently, spin\nrelaxation and dephasing are qualitatively modified compared with the case of\nthe intrinsic SOC. Furthermore, the fidelity of electric-dipole spin resonance\nbased on $\\vec\\Omega$ could be optimized, with potential applications in\nspin-based quantum computing."
    },
    {
        "anchor": "Time-resolved measurement of ambipolar edge magnetoplasmon transport in\n  InAs/InGaSb composite quantum wells: Time-resolved charge transport measurement for one-dimensional edge states is\na powerful means for investigating nonequilibrium charge dynamics and\nunderlying interaction effects therein. Here, we report a versatile on-chip\ntime-resolved transport measurement scheme that does not require a quantum\npoint contact and is therefore applicable to narrow-gap systems. We apply the\ntechnique to non-inverted InAs/In$_{x}$Ga$_{1-x}$Sb composite quantum wells,\nwhere its ambipolar character enables us to demonstrate the scheme in both the\nelectron and hole regimes separately using a single device. Time-resolved\nmeasurements in the quantum Hall regimes clearly exhibit the chirality of each\ncarrier, with pulsed charge waveforms observed only for one magnetic field\ndirection opposite for electrons and holes. Waveform analysis in the time\ndomain reveals reduced group velocity and broadening of edge magnetoplasmon\npulses in both the electron and hole regimes, suggesting the influence of\ncharge puddles in the bulk. Our time-resolved measurement scheme, applicable to\nvarious systems, will pave the way for investigations of dynamical properties\nof exotic topological edge states.",
        "positive": "Boosting Majorana zero modes: One-dimensional topological superconductors are known to host Majorana zero\nmodes at domain walls terminating the topological phase. Their nonabelian\nnature allows for processing quantum information by braiding operations which\nare insensitive to local perturbations, making Majorana zero modes a promising\nplatform for topological quantum computation. Motivated by the ultimate goal of\nexecuting quantum information processing on a finite timescale, we study domain\nwalls moving at a constant velocity. We exploit an effective Lorentz invariance\nof the Hamiltonian to obtain an exact solution of the associated quasiparticle\nspectrum and wave functions for arbitrary velocities. Essential features of the\nsolution have a natural interpretation in terms of the familiar relativistic\neffects of Lorentz contraction and time dilation. We find that the Majorana\nzero modes remain stable as long as the domain wall moves at subluminal\nvelocities with respect to the effective speed of light of the system. However,\nthe Majorana bound state dissolves into a continuous quasiparticle spectrum\nonce the domain wall propagates at luminal or even superluminal velocities.\nThis relativistic catastrophe implies that there is an upper limit for possible\nbraiding frequencies even in a perfectly clean system with an arbitrarily large\ntopological gap. We also exploit our exact solution to consider domain walls\nmoving past static impurities present in the system."
    },
    {
        "anchor": "Coherent spin-spin coupling mediated by virtual microwave photons: We report the coherent coupling of two electron spins at a distance via\nvirtual microwave photons. Each spin is trapped in a silicon double quantum dot\nat either end of a superconducting resonator, achieving spin-photon couplings\nup to around $g_s/2\\pi = 40 \\ \\text{MHz}$. As the two spins are brought into\nresonance with each other, but detuned from the photons, an avoided crossing\nlarger than the spin linewidths is observed with an exchange splitting around\n$2J/2\\pi = 20 \\ \\text{MHz}$. In addition, photon-number states are resolved\nfrom the shift $2\\chi_s/2\\pi = -13 \\ \\text{MHz}$ that they induce on the spin\nfrequency. These observations demonstrate that we reach the strong dispersive\nregime of circuit quantum electrodynamics with spins. Achieving spin-spin\ncoupling without real photons is essential to long-range two-qubit gates\nbetween spin qubits and scalable networks of spin qubits on a chip.",
        "positive": "Self-similarity of single-channel transmission for electron transport in\n  nanowires: We demonstrate that the single-channel transmission in the resonance\ntunneling regime exhibits self-similarity as a function of the nanowire length\nand the energy of incident electrons. The self-similarity is used to design the\nnonlinear transformation of the nanowire length and energy which, on the basis\nof known values of transmission for a certain region on the energy-length\nplane, yields transmissions for other regions on this plane. Test calculations\nwith a one-dimensional tight-binding model illustrate the described\ntransformations. Density function theory based transport calculations of Na\natomic wires confirm the existence of the self-similarity in the transmission."
    },
    {
        "anchor": "Negative Differential Conductance and Hot Phonons in Suspended Nanotube\n  Molecular Wires: Freely suspended metallic single-wall carbon nanotubes (SWNTs) exhibit\nreduced current carrying ability compared to those lying on substrates, and\nstriking negative differential conductance (NDC) at low electric fields.\nTheoretical analysis reveals significant self-heating effects including\nelectron scattering by hot non-equilibrium optical phonons. Electron transport\ncharacteristics under strong self-heating are exploited for the first time to\nprobe the thermal conductivity of individual SWNTs (~ 3600 Wm-1K-1 at T=300 K)\nup to ~700 K, and reveal a 1/T dependence expected for Umklapp phonon\nscattering at high temperatures.",
        "positive": "Nonlinear Hall effect induced by internal Coulomb interaction and phase\n  relaxation process in a four-terminal system with time-reversal symmetry: We numerically investigate the second-order nonlinear Hall transport\nproperties of a four-terminal system with time-reversal symmetry and broken\ninversion symmetry. Within the nonequilibrium Green's function formalism, the\nsecond-order nonlinear conductances are derived, where the internal Coulomb\npotential in response to external voltages is explicitly included to guarantee\nthe gauge invariance. For the system with single mirror symmetry Mx, nonlinear\nHall properties are only observable in the y direction and contributed solely\nfrom the second-order nonlinear effect. From the symmetry point of view, the\nobserved nonlinear Hall transport phenomena have one-to-one correspondence with\nthe Berry curvature dipole induced nonlinear Hall effect semiclassically\nobtained for the same Hamiltonian. In addition to the nonlinear Hall effect\noriginated from symmetries of the system, it is found that the internal Coulomb\npotential has the same symmetry of the four-terminal system, which gives rise\nto an extra nonlinear Hall response. Moreover, the phase relaxation mechanism\nmodeled by virtual probes leads to the dephasing-induced nonlinear Hall effect."
    },
    {
        "anchor": "Electron emission from a metal nano-tip by ultrashort laser pulses: We theoretically investigate the interaction of near-infrared few cycle laser\npulses of moderate intensity with nano-scale metal tips. Macroscopic field\nenhancement leads to coherent electron emission from the tip apex. Electron\nspectra are simulated with time-dependent density functional theory (TDDFT). We\ninvestigate the dependence of the simulated electron spectra on the choice of\nexchange-correlation potential and atomic core pseudo-potential.",
        "positive": "Enhanced Thermal Conductivity in Nanofluids Under the Action of\n  Oscillating Force Fields: The thermal conductivity of nanoparticles colloidal suspensions, submitted to\nthe action of an external force field has been calculated by non equilibrium\nmolecular dynamics simulations. For driven forces in the radio frequency and\nmicrowave ranges, we show that the thermal conductivity of nanofluids can be\nstrongly enhanced without cluster formation."
    },
    {
        "anchor": "Current-Induced Helicity Reversal of a Single Skyrmionic Bubble Chain in\n  a Nanostructured Frustrated Magnet: Helicity indicates the in-plane magnetic-moment swirling direction of a\nskyrmionic configuration. The ability to reverse the helicity of a skyrmionic\nbubble via purely electrical means has been predicted in frustrated magnetic\nsystems, however its experimental observation has remained challenging. Here,\nwe experimentally demonstrate the current-driven helicity reversal of the\nskyrmionic bubble in a nanostructured frustrated Fe3Sn2 magnet. The critical\ncurrent density required to trigger the helicity reversal is 109 - 1010 A/m2,\nwith a corresponding pulse-width varying from 1 {\\mu}s to 100 ns. Computational\nsimulations reveal that both the pinning effect and dipole-dipole interaction\nplay a crucial role in the helicity-reversal process.",
        "positive": "Andreev reflection adjusting in the multi-terminal device with the kink\n  states: At the domain wall between two regions with the opposite Chern number, there\nshould be the one-dimensional chiral states, which are called as the kink\nstates. The kink states are robust for the lattice deformations. We design a\nmulti-terminal device with the kink states to study the local Andreev\nreflection and the crossed Andreev reflection. The coefficient of the crossed\nAndreev reflection can reach 1 in the four-terminal device. Besides adjusting\nthe phase difference between superconductors, the local Andreev reflection and\nthe crossed Andreev reflection can be controlled by changing the on-site energy\nand the stagger energy in the four-terminal device. Our results give some new\nideas to design the quantum device in the future."
    },
    {
        "anchor": "Detection of persistent current correlation in cavity-QED: We simulated the radiative response of the cavity quantum electrodynamics\n(QED) inductively coupled to the ring pierced by magnetic flux, and analyzed\nits spectral dependence to get insight into persistent current dynamics.\nCurrent fluctuations in the ring induce changes in the microwave resonator:\nshifting the resonant frequency and changing its damping. We use the linear\nresponse theory and calculate the current response function by means of the\nGreen function technique. Our model contains two quantum dots which divide the\nring into two arms with different electron transfers. There are two opposite\n(symmetric and asymmetric) components of the persistent current, which\ninterplay can be observed in the response functions. The resonator reflectance\nshows characteristic shifts in the dispersive regime and avoided crossings at\nthe resonance points. The magnitude of the resonator frequency shift is greater\nfor coupling to the arm with higher transparency. Fluctuations of the symmetric\ncomponent of the persistent current are relevant for a wide range of the\nAharovov-Bohm phase $\\phi$, while the asymmetric component becomes dominant\nclose to $\\phi\\approx \\pi$ (when the total persistent current changes its\norientation)",
        "positive": "Imaging thermal conductivity with nanoscale resolution using a scanning\n  spin probe: The ability to probe nanoscale heat flow in a material is often limited by\nlack of spatial resolution. Here, we use a diamond-nanocrystal-hosted\nnitrogen-vacancy centre attached to the apex of a silicon thermal tip as a\nlocal temperature sensor. We apply an electrical current to heat up the tip and\nrely on the NV to monitor the thermal changes the tip experiences as it is\nbrought into contact with surfaces of varying thermal conductivity. With the\naid of a combined AFM/confocal setup, we image phantom microstructures with\nnanoscale resolution, and attain excellent agreement between the thermal\nconductivity and topographic maps. The small mass and high thermal conductivity\nof the diamond host make the time response of our technique short, which we\ndemonstrate by monitoring the tip temperature upon application of a heat pulse.\nOur approach promises multiple applications, from the investigation of phonon\ndynamics in nanostructures to the characterization of heterogeneous phase\ntransitions and chemical reactions in various solid-state systems."
    },
    {
        "anchor": "Spin resonance without spin splitting: We predict that a single-level quantum dot without discernible splitting of\nits spin states develops a spin-precession resonance in charge transport when\nembedded into a spin valve. The resonance occurs in the generic situation of\nCoulomb blockaded transport with ferromagnetic leads whose polarizations\ndeviate from perfect antiparallel alignment. The resonance appears when\nelectrically tuning the interaction-induced exchange field perpendicular to one\nof the polarizations -- a simple condition relying on vectors in contrast to\nusual resonance conditions associated with energy splittings. The spin\nresonance can be detected by stationary dI/dV spectroscopy and by oscillations\nin the time-averaged current using a gate-pulsing scheme. The generic\nnoncollinearity of the ferromagnets and junction asymmetry allow for an\nall-electric determination of the spin-injection asymmetry, the anisotropy of\nspin relaxation, and the magnitude of the exchange field. We also investigate\nthe impact of a nearby superconductor on the resonance position. Our simplistic\nmodel turns out to be generic for a broad class of coherent few-level quantum\nsystems.",
        "positive": "Transition from isolated to overlapping resonances in the open system of\n  interacting fermions: We study the statistical properties of resonance widths and spacings in an\nopen system of interacting fermions at the transition between isolated and\noverlapping resonances, where a radical change in the width distribution\noccurs. Our main interest is to reveal how this transition is influenced by the\nonset of chaos in the internal dynamics as the strength of random two-body\ninteraction between the particles increases. We have found that in the region\nof overlapped resonances, the fluctuations of the widths (rather than their\nmean values) are strongly affected by the onset of an internal chaos. The\nresults may be applied to the analysis of neutron cross sections, as well as in\nthe physics of mesoscopic devices with strongly interacting electrons."
    },
    {
        "anchor": "Conductance anomalies in quantum wires: We study the conductance threshold of clean nearly straight quantum wires in\nthe magnetic field. As a quantitative example we solve exactly the scattering\nproblem for two-electrons in a wire with planar geometry and a weak bulge. From\nthe scattering matrix we determine conductance via the Landauer-Buettiker\nformalism. The conductance anomalies found near 0.25(2e^2/h) and 0.75(2e^2/h)\nare related to a singlet resonance and a triplet resonance, respectively, and\nsurvive to temperatures of a few degrees. With increasing in-plane magnetic\nfield the conductance exhibits a plateau at e^2/h, consistent with recent\nexperiments.",
        "positive": "A scattering matrix approach to quantum pumping: Beyond the\n  small-ac-driving-amplitude limit: In the adiabatic and weak-modulation quantum pump, net electron flow is\ndriven from one reservoir to the other by absorbing or emitting an energy\nquantum $\\hbar \\omega $ from or to the reservoirs. In our approach, high-order\ndependence of the scattering matrix on the time is considered. Non-sinusoidal\nbehavior of strong pumping is revealed. The relation between the pumped current\nand the ac driving amplitude varies from power of 2, 1 to 1/2 when stronger\nmodulation is exerted. Open experimental observation can be interpreted by\nmulti-energy-quantum-related processes."
    },
    {
        "anchor": "Manipulating Topological Edge Spins in One-Dimensional Optical Lattice: We propose to observe and manipulate topological edge spins in 1D optical\nlattice based on currently available experimental platforms. Coupling the\natomic spin states to a laser-induced periodic Zeeman field, the lattice system\ncan be driven into a symmetry protected topological (SPT) phase, which belongs\nto the chiral unitary (AIII) class protected by particle number conservation\nand chiral symmetries. In free-fermion case the SPT phase is classified by a\n$Z$ invariant which reduces to $Z_4$ with interactions. The zero edge modes of\nthe SPT phase are spin-polarized, with left and right edge spins polarized to\nopposite directions and forming a topological spin-qubit (TSQ). We demonstrate\na novel scheme to manipulate the zero modes and realize single spin control in\noptical lattice. The manipulation of TSQs has potential applications to quantum\ncomputation.",
        "positive": "Enhancement of the spin-gap in fully occupied two-dimensional Landau\n  levels: Polarization-resolved magneto-luminescence, together with simultaneous\nmagneto-transport measurements, have been performed on a two-dimensional\nelectron gas (2DEG) confined in CdTe quantum well in order to determine the\nspin-splitting of fully occupied electronic Landau levels, as a function of the\nmagnetic field (arbitrary Landau level filling factors) and temperature. The\nspin splitting, extracted from the energy separation of the \\sigma+ and \\sigma-\ntransitions, is composed of the ordinary Zeeman term and a many-body\ncontribution which is shown to be driven by the spin-polarization of the 2DEG.\nIt is argued that both these contributions result in a simple, rigid shift of\nLandau level ladders with opposite spins."
    },
    {
        "anchor": "Full configuration interaction simulations of exchange-coupled donors in\n  silicon using multi-valley effective mass theory: Donor spin in silicon have achieved record values of coherence times and\nsingle-qubit gate fidelities. The next stage of development involves\ndemonstrating high-fidelity two-qubit logic gates, where the most natural\ncoupling is the exchange interaction. To aid the efficient design of scalable\ndonor-based quantum processors, we model the two-electron wave function using a\nfull configuration interaction method within a multi-valley effective mass\ntheory. We exploit the high computational efficiency of our code to investigate\nthe exchange interaction, valley population, and electron densities for two\nphosphorus donors in a wide range of lattice positions, orientations, and as a\nfunction of applied electric fields. The outcomes are visualized with\ninteractive images where donor positions can be swept while watching the valley\nand orbital components evolve accordingly. Our results provide a physically\nintuitive and quantitatively accurate understanding of the placement and tuning\ncriteria necessary to achieve high-fidelity two-qubit gates with donors in\nsilicon.",
        "positive": "Macroscopic Magnetic Dynamics: Ferromagnetic metals and spin-polarized $^{3}$He are spin 1/2 systems with\nthe same macroscopic symmetry, and thus should have macroscopic magnetic\ndynamics with the same structure. Using Onsager's irreversible thermodynamics,\nwe develop a theory for these systems that contains two relaxation times (one\nfor the magnetization $\\vec{M}$ and the other for the spin current\n$\\vec{J}_{i}$), a magnetic compressibility, and a mean-field parameter.\nCurrently spintronics data on metallic ferromagnets are analyzed using a\ncomplex decay length from a theory employing a diffusion constant, a lifetime,\nand a mean-field parameter. The present theory leads to a complex decay length\nwith the same structure. On neglecting decay of $\\vec{M}$, the present theory\napplies to liquids and gases. For macroscopic equations the particle statistics\nis not relevant, so the theory also applies to bosons. The theory predicts a\nlongitudinal spin wave whose velocity we estimate for liquid $^{3}$He and for\nparamagnetic metals; but such a wave should also occur for ferromagnets and for\ngases."
    },
    {
        "anchor": "Ultra-Low-Energy Straintronics Using Multiferroic Composites: The primary impediment to continued improvement of charge-based electronics\nis the excessive energy dissipation incurred in switching a bit of information.\nWith suitable choice of materials, devices made of multiferroic composites,\ni.e., strain-coupled piezoelectric-magnetostrictive heterostructures, dissipate\nminiscule amount of energy of ~1 attojoule at room-temperature, while switching\nin sub-nanosecond delay. Apart from devising memory bits, such devices can be\nalso utilized for building logic, so that they can be deemed suitable for\ncomputing purposes as well. Here, we first review the current state of the art\nfor building nanoelectronics using multiferroic composites. On a recent\ndevelopment, it is shown that these multiferroic straintronic devices can be\nalso utilized for analog signal processing, with suitable choice of materials.\nBy solving stochastic Landau-Lifshitz-Gilbert equation of magnetization\ndynamics at room-temperature, it is shown that we can achieve a voltage gain,\ni.e., these straintronic devices can act as voltage amplifiers.",
        "positive": "Spin and valley-orbit splittings in SiGe/Si heterostructures: Spin and valley-orbit splittings are calculated in SiGe/Si/SiGe quantum wells\n(QWs) by using the tight-binding approach. In accordance with the symmetry\nconsiderations an existence of spin splitting of electronic states in perfect\nQWs with an odd number of Si atomic planes is microscopically demonstrated. The\nspin splitting oscillates with QW width and these oscillations related to the\ninter-valley reflection of an electron wave from the interfaces. It is shown\nthat the splittings under study can efficiently be described by an extended\nenvelope-function approach taking into account the spin- and valley-dependent\ninterface mixing. The obtained results provide a theoretical base to the\nexperimentally observed electron spin relaxation times in SiGe/Si/SiGe QWs."
    },
    {
        "anchor": "Ultrasmall double junction in terms of orthogonal polynomials: The ``orthodox theory'' of a single electron double junction is dealt with.\nIt is shown that the stationary solution of the underlying master equation\nallows the construction of any time-dependent solution in terms of orthogonal\npolynomials. The approach pays off if the stationary solution becomes simple.\nTwo special cases are considered. We use the time-dependent solution to\ncalculate the current noise in these cases.",
        "positive": "Probing the Optical Dynamics of Quantum Emitters in Hexagonal Boron\n  Nitride: Hexagonal boron nitride is a van der Waals material that hosts\nvisible-wavelength quantum emitters at room temperature. However, experimental\nidentification of the quantum emitters' electronic structure is lacking, and\nkey details of their charge and spin properties remain unknown. Here, we probe\nthe optical dynamics of quantum emitters in hexagonal boron nitride using\nphoton emission correlation spectroscopy. Several quantum emitters exhibit\nideal single-photon emission with noise-limited photon antibunching,\n$g^{(2)}(0)=0$. The photoluminescence emission lineshapes are consistent with\nindividual vibronic transitions. However, polarization-resolved excitation and\nemission suggests the role of multiple optical transitions, and photon emission\ncorrelation spectroscopy reveals complicated optical dynamics associated with\nexcitation and relaxation through multiple electronic excited states. We\ncompare the experimental results to quantitative optical dynamics simulations,\ndevelop electronic structure models that are consistent with the observations,\nand discuss the results in the context of ab initio theoretical calculations."
    },
    {
        "anchor": "Tunable quantum criticalities in an isospin extended Hubbard model\n  simulator: Studying strong electron correlations has been an essential driving force for\npushing the frontiers of condensed matter physics. In particular, in the\nvicinity of correlation-driven quantum phase transitions (QPTs), quantum\ncritical fluctuations of multiple degrees of freedom facilitate exotic\nmany-body states and quantum critical behaviors beyond Landau's framework.\nRecently, moir\\'e heterostructures of van der Waals materials have been\ndemonstrated as a highly tunable quantum platform for exploring fascinating\nstrongly correlated quantum physics. Here, we report the observation of tunable\nquantum criticalities in an experimental simulator of extended Hubbard model\nwith spin-valley isospins arising in chiral-stacked twisted double bilayer\ngraphene. Scaling analysis shows a quantum two-stage criticality manifesting\ntwo distinct quantum critical points as the generalized Wigner crystal transits\nto a Fermi liquid by varying the displacement field, suggesting the emergence\nof a critical intermediate phase. The quantum two-stage criticality evolves\ninto a quantum pseudo criticality as a high parallel magnetic field is applied.\nIn such pseudo criticality, we find that the quantum critical scaling is only\nvalid above a critical temperature, indicating a weak first-order QPT therein.\nOur results demonstrate a highly tunable solid-state simulator with intricate\ninterplay of multiple degrees of freedom for exploring exotic quantum critical\nstates and behaviors.",
        "positive": "Probing edge state conductance in ultra-thin topological insulator films: Quantum spin Hall (QSH) insulators have unique electronic properties,\ncomprising a band gap in their two-dimensional interior and one-dimensional\nspin-polarized edge states in which current flows ballistically. In scanning\ntunneling microscopy (STM), the edge states manifest themselves as a localized\ndensity of states. However, there is a significant research gap between the\nobservation of edge states in nanoscale spectroscopy, and the detection of\nballistic transport in edge channels which typically relies on transport\nexperiments with microscale lithographic contacts. Here, we study few-layer\nfilms of the three-dimensional topological insulator\n(Bi$_{x}$Sb$_{1-x})_2$Te$_3$, for which a topological transition to a\ntwo-dimensional topological QSH insulator phase has been proposed. Indeed, an\nedge state in the local density of states is observed within the band gap. Yet,\nin nanoscale transport experiments with a four-tip STM, 2 and 3 quintuple layer\nfilms do not exhibit a ballistic conductance in the edge channels. This\ndemonstrates that the detection of edge states in spectroscopy can be\nmisleading with regard to the identification of a QSH phase. In contrast,\nnanoscale multi-tip transport experiments are a robust method for effectively\npinpointing ballistic edge channels, as opposed to trivial edge states, in\nquantum materials."
    },
    {
        "anchor": "Exceptional high Seebeck Coefficient and Gas-Flow-Induced Voltage in\n  Multilayer Graphene: Monolayer graphene shows Seebeck coefficient several times and\ngas-flow-induced voltage twenty times higher than that of bulk graphite. Here\nwe find that the Seebeck coefficient of multilayer graphene increases\nmonotonically with increasing layer and reaches its peak value at hexa-layer\n~77% higher than for monolayer and then decreases, although the electric\nresistance decreases monotonically with increasing layer. The flow-induced\nvoltage is significantly higher in 2, 4, 5, 6, 7 layered graphene than in 1, 3,\n8 layered one, against the prevailing view that it should be proportional to\nSeebeck coefficient. These thickness effects are also in sharp contrast to that\nin continuous aluminum nanofilms.",
        "positive": "Optical control of the spin state of two Mn atoms in a quantum dot: We report on the optical spectroscopy of the spin of two magnetic atoms (Mn)\nembedded in an individual quantum dot interacting with either a single\nelectron, a single exciton and single trion. As a result of their interaction\nto a common entity, the Mn spins become correlated. The dynamics of this\nprocess is probed by time resolved spectroscopy, that permits to determine the\noptical orientation time in the range of a few tens of $ns$. In addition, we\nshow that the energy of the collective spin states of the two Mn atoms can be\ntuned through the optical Stark effect induced by a resonant laser field."
    },
    {
        "anchor": "Fermionic Mach-Zehnder interferometer subject to a quantum bath: We study fermions in a Mach-Zehnder interferometer, subject to a\nquantum-mechanical environment leading to inelastic scattering, decoherence,\nrenormalization effects, and time-dependent conductance fluctuations. Both the\nloss of interference contrast as well as the shot noise are calculated, using\nequations of motion and leading order perturbation theory. The full dependence\nof the shot-noise correction on setup parameters, voltage, temperature and the\nbath spectrum is presented. We find an interesting contribution due to\ncorrelations between the fluctuating renormalized phase shift and the output\ncurrent, discuss the limiting behaviours at low and high voltages, and compare\nwith simpler models of dephasing.",
        "positive": "Quantification of competing magnetic states and switching pathways in\n  curved nanowires by direct dynamic imaging: For viable applications, spintronic devices based e.g. on domain wall motion\nneed to be highly reliable with stable magnetization states and highly\nreproducible switching pathways transforming one state to another. The\nexistence of multiple stable states and switching pathways in a system is a\ndefinitive barrier for device operation, yet rare and stochastic events are\ndifficult to detect and understand. We demonstrate an approach to quantify\ncompeting magnetic states and stochastic switching pathways based on\ntime-resolved scanning electron microscopy with polarization analysis, applied\nto the technologically relevant control of vortex domain wall chirality via\nfield and curvature in curved wires. While being a pump-probe technique, our\nanalysis scheme nonetheless allows for the disentanglement of different\noccurring dynamic pathways and we can even identify the rare events leading to\nchanges from one magnetization switching pathway to another pathway via\ntemperature- and geometry-dependent measurements. The experimental imaging is\nsupported by micromagnetic simulations to reveal the mechanisms responsible for\nthe change of the pathway. Together the results allow us to explain the origin\nand details of the domain wall chirality control and to quantify the frequency\nand the associated energy barriers of thermally activated changes of the states\nand switching pathways."
    },
    {
        "anchor": "Asymmetric Cherenkov acoustic reverse in topological insulators: A general phenomenon of the Cherenkov radiation known in optics or acoustics\nof conventional materials is a formation of a forward cone of, respectively,\nphotons or phonons emitted by a particle accelerated above the speed of light\nor sound in those materials. Here we suggest three-dimensional topological\ninsulators as a unique platform to fundamentally explore and practically\nexploit the acoustic aspect of the Cherenkov effect. We demonstrate that\napplying an in-plane magnetic field to a surface of a three-dimensional\ntopological insulator one may suppress the forward Cherenkov sound up to zero\nat a critical magnetic field. Above the critical field the Cherenkov sound\nacquires pure backward nature with the polar distribution differing from the\nforward one generated below the critical field. Potential applications of this\nasymmetric Cherenkov reverse are in design of low energy electronic devices\nsuch as acoustic ratchets or, in general, in low power design of electronic\ncircuits with a magnetic field control of the direction and magnitude of the\nCherenkov dissipation.",
        "positive": "Scaling Behavior of Bipolar Nanopore Rectification with Multivalent Ions: We present a scaling behavior of a rectifying bipolar nanopore as a function\nof the parameter $\\xi=R_{\\mathrm{P}}/(\\lambda z_{\\mathrm{if}})$, where\n$R_{\\mathrm{P}}$ is the radius of the pore, $\\lambda$ is the characteristic\nscreening length of the electrolyte filling the pore, and\n$z_{\\mathrm{if}}=\\sqrt{z_{+}|z_{-}|}$ is a scaling factor that makes scaling\nwork for electrolytes containing multivalent ions ($z_{+}$ and $z_{-}$ are\ncation and the anion valences). By scaling we mean that the rectification of\nthe pore (defined as the ratio of currents in the forward and reversed biased\nstates) depends on pore radius, concentration, $c$, and ion valences via the\nparameter $\\xi$ implicitly. This feature is based on the fact that\nrectification depends on the voltage-sensitive appearance of depletion zones\nthat, in turn, depend on the relation of $R_{\\mathrm{P}}$ to the rescaled\nscreening length $\\lambda z_{\\mathrm{if}}$. In this modeling study, we use the\nPoisson-Nernst-Planck (PNP) theory and a particle simulation method, the Local\nEquilibrium Monte Carlo (LEMC). The latter can compute ion correlations that\nare ignored in the mean-field treatment of PNP and that are very important for\nmultivalent ions (we show results for 1:1, 2:1, 3:1, and 2:2 electrolytes). In\naddition to the $z_{\\mathrm{if}}$ factor, we show that one must choose a\nscreening length appropriate to the system, in our case the Debye length for\n$\\lambda$ for PNP and the screening length given by the Mean Spherical\nApproximation for LEMC."
    },
    {
        "anchor": "Low-noise amplification and frequency conversion with a multiport\n  microwave optomechanical device: High-gain amplifiers of electromagnetic signals operating near the quantum\nlimit are crucial for quantum information systems and ultrasensitive quantum\nmeasurements. However, the existing techniques have a limited gain-bandwidth\nproduct and only operate with weak input signals. Here we demonstrate a\ntwo-port optomechanical scheme for amplification and routing of microwave\nsignals, a system that simultaneously performs high-gain amplification and\nfrequency conversion in the quantum regime. Our amplifier, implemented in a\ntwo-cavity microwave optomechanical device, shows 41 dB of gain and has a high\ndynamic range, handling input signals up to $10^{13}$ photons per second, three\norders of magnitude more than corresponding Josephson parametric amplifiers. We\nshow that although the active medium, the mechanical resonator, is at a high\ntemperature far from the quantum limit, only 4.6 quanta of noise is added to\nthe input signal. Our method can be readily applied to a wide variety of\noptomechanical systems, including hybrid optical-microwave systems, creating a\nuniversal hub for signals at the quantum level.",
        "positive": "A direct Numerov sixth order numerical scheme to accurately solve the\n  unidimensional Poisson equation with Dirichlet boundary conditions: In this article, we present an analytical direct method, based on a Numerov\nthree-point scheme, which is sixth order accurate and has a linear execution\ntime on the grid dimension, to solve the discrete one-dimensional Poisson\nequation with Dirichlet boundary conditions. Our results should improve\nnumerical codes used mainly in self-consistent calculations in solid state\nphysics."
    },
    {
        "anchor": "Symmetries, Topological Phases and Bound States in the One-Dimensional\n  Quantum Walk: Discrete-time quantum walks have been shown to simulate all known topological\nphases in one and two dimensions. Being periodically driven quantum systems,\ntheir topological description, however, is more complex than that of closed\nHamiltonian systems. We map out the topological phases of the particle-hole\nsymmetric one-dimensional discrete-time quantum walk. We find that there is no\nchiral symmetry in this system: its topology arises from the particle-hole\nsymmetry alone. We calculate the Z2 \\times Z2 topological invariant in a simple\nway that is consistent with a general definition for 1-dimensional periodically\ndriven quantum systems. These results allow for a transparent interpretation of\nthe edge states on a finite lattice via the the bulk-boundary correspondance.\nWe find that the bulk Floquet operator does not contain all the information\nneeded for the topological invariant. As an illustration to this statement, we\nshow that in the split-step quantum walk, the edges between two bulks with the\nsame Floquet operator can host topologically protected edge states.",
        "positive": "Probing valley filtering effect by Andreev reflection in zigzag graphene\n  nanoribbon: Ballistic point contact (BPC) with zigzag edges in graphene is a main\ncandidate of a valley filter, in which the polarization of the valley degree of\nfreedom can be selected by using a local gate voltage. Here, we propose to\ndetect the valley filtering effect by Andreev reflection. Because electrons in\nthe lowest conduction band and the highest valence band of the BPC possess\nopposite chirality, the inter-band Andreev reflection is strongly suppressed,\nafter multiple scattering and interference. We draw this conclusion by both the\nscattering matrix analysis and the numerical simulation. The Andreev reflection\nas a function of the incident energy of electrons and the local gate voltage at\nthe BPC is obtained, by which the parameter region for a perfect valley filter\nand the direction of valley polarization can be determined. The Andreev\nreflection exhibits an oscillatory decay with the length of the BPC, indicating\na negative correlation to valley polarization."
    },
    {
        "anchor": "Forces between functionalized silica nanoparticles in solution: To prevent the flocculation and phase separation of nanoparticles in\nsolution, nanoparticles are often functionalized with short chain surfactants.\nHere we present fully-atomistic molecular dynamics simulations which\ncharacterize how these functional coatings affect the interactions between\nnanoparticles and with the surrounding solvent. For 5 nm diameter silica\nnanoparticles coated with poly(ethylene oxide) (PEO) oligomers in water, we\ndetermined the hydrodynamic drag on two approaching nanoparticles moving\nthrough solvent and on a single nanoparticle as it approaches a planar surface.\nIn most circumstances, acroscale fluid theory accurately predicts the drag on\nthese nano-scale particles. Good agreement is seen with Brenner's analytical\nsolutions for wall separations larger than the soft nanoparticle radius. For\ntwo approaching coated nanoparticles, the solvent-mediated\n(velocity-independent) and lubrication (velocity-dependent) forces are purely\nrepulsive and do not exhibit force oscillations that are typical of uncoated\nrigid spheres.",
        "positive": "Proposal for the detection and braiding of Majorana fermions in a\n  quantum spin Hall insulator: We show how a quantum dot with a ballistic single-channel point contact to a\nsuperconductor can be created by means of a gate electrode at the edge of a\nquantum spin Hall insulator (such as an InAs/GaSb quantum well). A weak\nperpendicular magnetic field traps a Majorana zero-mode, so that it can be\nobserved in the gate-voltage-averaged differential conductance <dI/dV> as a\n4e^2/h zero-bias peak above a (2/3{\\pi}^2 - 4)e^2/h background. The\none-dimensional edge does not permit the braiding of pairs of Majorana\nfermions, but this obstacle can be overcome by coupling opposite edges at a\nconstriction, allowing for a demonstration of non-Abelian statistics."
    },
    {
        "anchor": "Periphery deformations and tunneling at correlated quantum-Hall edges: We argue that, at any filling factor, correlated quantum-Hall systems possess\na set of chiral boson excitations which are generated by electronically rigid\ndeformations of the system's periphery. We submit that tunneling electrons can\nbe accommodated, at low energies, in these systems only by\nperiphery-deformation excitations. This property would explain the recent\nobservation of a tunneling density of states at the edge which does not exhibit\na strong dependence on the occurrence or absence of the quantum Hall effect and\nhas a power-law dependence on energy with exponent (inverse filling factor)-1.",
        "positive": "Weak localization corrections to the thermal conductivity in $s$-wave\n  superconductors: We study the thermal conductivity in disordered $s$-wave superconductors.\nExpanding on previous works for normal metals, we develop a formalism that\ntackles particle diffusion as well as the weak localization (WL) and weak\nanti-localization (WAL) effects. Using a Green's functions diagrammatic\ntechnique, which takes into account the superconducting nature of the system by\nworking in Nambu space, we identify the system's low-energy modes, the diffuson\nand the Cooperon. The time scales that characterize the diffusive regime are\nenergy dependent; this is in contrast with the the normal state, where the\nrelevant time scale is the mean free time $\\tau_e$, independent of energy. The\nenergy dependence introduces a novel energy scale $\\varepsilon_*$, which in\ndisordered superconductors ($\\tau_e \\Delta\\ll 1$, with $\\Delta$ the gap) is\ngiven by $\\varepsilon_* = \\sqrt{\\Delta/\\tau_e}$. From the diffusive behavior of\nthe low-energy modes, we obtain the WL correction to the thermal conductivity.\nWe give explicitly expressions in two dimensions. We determine the regimes in\nwhich the correction depends explicitly on $\\varepsilon_*$ and propose an\noptimal regime to verify our results in an experiment."
    },
    {
        "anchor": "Chiral detection of Majorana bound states at the edge of a quantum spin\n  Hall insulator: A hybrid setup consisting of a superconductivity-proximitized quantum spin\nHall (QSH) insulator and a quantum anomalous Hall (QAH) insulator is proposed\nfor chiral injection of electrons into the Majorana bound state (MBS). An\nunexplored region of the phase space involving the exchange field induced boost\nof the helical edge state is then proposed for the detection of the MBS. 2-D\ntransport simulations of our proposed setup is compared with the corresponding\nsetup in the absence of the QAH region, when moderate disorder and a small but\nfinite bulk out-of-plane magnetic field and a Rashba field are included. The\nremarkable contrast between the two results demonstrates the possibility for an\nunprecedented immunity from disorder-induced masking of the MBS detection in\nour proposed setup.",
        "positive": "Observation of integer and fractional quantum anomalous Hall effects in\n  twisted bilayer MoTe2: The interplay between strong correlations and topology can lead to the\nemergence of intriguing quantum states of matter. One well-known example is the\nfractional quantum Hall effect, where exotic electron fluids with fractionally\ncharged excitations form in partially filled Landau levels. The emergence of\ntopological moir\\'e flat bands provides exciting opportunities to realize the\nlattice analogs of both the integer and fractional quantum Hall states without\nthe need for an external magnetic field. These states are known as the integer\nand fractional quantum anomalous Hall (IQAH and FQAH) states. Here, we present\ndirect transport evidence of the existence of both IQAH and FQAH states in\ntwisted bilayer MoTe2 (AA stacked). At zero magnetic field, we observe\nwell-quantized Hall resistance of h/e2 around moir\\'e filling factor {\\nu} = -1\n(corresponding to one hole per moir\\'e unit cell), and nearly-quantized Hall\nresistance of 3h/2e2 around {\\nu} = -2/3, respectively. Concomitantly, the\nlongitudinal resistance exhibits distinct minima around {\\nu} = -1 and -2/3.\nThe application of an electric field induces topological quantum phase\ntransition from the IQAH state to a charge transfer insulator at {\\nu} = -1,\nand from the FQAH state to a generalized Wigner crystal state, further\ntransitioning to a metallic state at {\\nu} = -2/3. Our study paves the way for\nthe investigation of fractionally charged excitations and anyonic statistics at\nzero magnetic field based on semiconductor moir\\'e materials."
    },
    {
        "anchor": "Monolayer V2MX4: A new family of quantum anomalous Hall insulators: We theoretically propose that the van der Waals layered ternary transition\nmetal chalcogenide V$_2 MX_4$ ($M=$ W, Mo; $X=$ S, Se) is a new family of\nquantum anomalous Hall insulators with sizable bulk gap and Chern number\n$\\mathcal{C}=-1$. The large topological gap originates from the \\emph{deep}\nband inversion between spin up bands contributed by $d_{xz},d_{yz}$ orbitals of\nV and spin down band from $d_{z^2}$ orbital of $M$ at Fermi level. Remarkably,\nthe Curie temperature of monolayer V$_2 MX_4$ is predicted to be much higher\nthan that of monolayer MnBi$_2$Te$_4$. Furthermore, the thickness dependence of\nthe Chern number for few multilayers shows interesting oscillating behavior.\nThe general physics from the $d$-orbitals here applies to a large class of\nternary transition metal chalcogenide such as Ti$_2$W$X_4$ with the space group\n$P$-$42m$. These interesting predictions, if realized experimentally, could\ngreatly promote the research and application of topological quantum physics.",
        "positive": "Enabling remote quantum emission in 2D semiconductors via porous\n  metallic networks: The interaction between two-dimensional crystals (2DCs) and metals is\nubiquitous in 2D material research. Here we report how 2DC overlayers influence\nthe recrystallization of relatively thick metal films and the subsequent\nsynergetic benefits this provides for coupling surface plasmon-polaritons\n(SPPs) to photon emission in 2D semiconductors. We show that annealing 2DC/Au\nfilms on SiO2 results in a 'reverse epitaxial' process where initially\nnanocrystalline Au films become highly textured and in close crystallographic\nregistry to the 2D crystal overlayer. With continued annealing, the metal\nunderlayer dewets to form an oriented pore enabled network (OPEN) film in which\nthe 2DC overlayer remains suspended above or coats the inside of the metal\npores. This OPEN film geometry supports SPPs launched by either direct laser\nexcitation or by light emitted from the TMD semiconductor itself, where energy\nin-coupling and out-coupling occurs at the metal pore sites such that\ndielectric spacers between the metal and 2DC layer are unnecessary. At low\ntemperatures a high density of single-photon emitters (SPEs) is present across\nan OPEN-WSe2 film, and we demonstrate non-local excitation of SPEs at a\ndistance of 17 {\\mu}m with minimal loss of photon purity. Our results suggest\nthe OPEN film geometry is a versatile platform that could facilitate the use of\nlayered materials in quantum optics systems."
    },
    {
        "anchor": "Origin and Electronic Behavior of Improper Ferroelectricity in AB2\n  (A=Cr, Mo, W; B=S, Se, Te) Transition Metal Dichalcogenides: Persistent electrical polarized states are fundamentally important to the\nelectric industry as they can be used in the non-volatile memory, the\nartificial neuromorphic network, and negative capacitors, making ultralow\nenergy consumption electronic devises possible. With the recent development in\nlow dimensional ferroelectric materials, emerging 2D out-of-plane ferroelectric\nmaterials like MoTe2 have great potential for future development. Despite\nprevious phenomenological studies, the underlying microscopic origin of\nferroelectricity is still missing. Here, using density functional theory and\nWannier function methods, we reveal that the origin of ferroelectricity of\nthese transition metal dichalcogenides comes from the Jahn taller effect and\nfollowed by a covalent bonding between transition metal atoms. Moreover, the\natypical electronic behavior of these monolayer AB2 (A=Cr, Mo, W; B=S, Se, Te)\nTMDs compare to traditional improper ferroelectrics hints a strong electronic\norigin of the polarization, suitable for future industrial applications.",
        "positive": "Cooper pair splitter in a photonic cavity: Detection of Andreev\n  scatterings: We simulated the radiative response of the cavity quantum electrodynamics\n(QED) coupled to the double quantum dot Cooper pair splitter and analyzed its\nspectral dependence to get insight into dynamics of the Cooper pair transfers.\nThe model is confined to the energy subspace where two entangled electrons are\ntransferred to two normal electrodes through the inter-dot singlet state on two\nproximitized quantum dots. Our research is focused on the Andreev scatterings\nin the subgap regime, for which the local charge susceptibility $\\Pi(\\omega_p)$\nis derived, by means of Keldysh Green functions, in a whole bias voltage range.\nIn particular, in the large voltage limit the spectrum of $\\Pi(\\omega_p)$ is\nexpressed by a simple analytical formula, which shows various dissipation\nprocesses related with photon-induced transitions between the Andreev bound\nstates."
    },
    {
        "anchor": "Interactions between two C60 molecules measured by scanning probe\n  microscopies: C60-functionalized tips are used to probe C60 molecules on Cu(111) with\nscanning tunneling and atomic force microscopy. Distinct and complex\nintramolecular contrasts are found. Maximal attractive forces are observed when\nfor both molecules a [6,6] bond faces a hexagon of the other molecule. Density\nfunctional theory calculations including parameterized van der Waals\ninteractions corroborate the observations.",
        "positive": "Ambient Effects on Photogating in MoS2 Photodetectors: Atomically thin transition metal dichalcogenides (TMDs) are ideal candidates\nfor ultrathin optoelectronics that is flexible and semitransparent.\nPhotodetectors based on TMDs show remarkable performance, with responsivity and\ndetectivity higher than 10^3 A/W and 10^12 Jones, respectively, but they are\nplagued by response times as slow as several tens of seconds. Although it is\nwell established that gas adsorbates such as water and oxygen create charge\ntraps and significantly increase both the responsivity and the response time,\nthe underlying mechanism is still unclear. Here we study the influence of\nadsorbates on MoS2 photodetectors under ambient conditions, vacuum and\nillumination at different wavelengths. We show that, for wavelengths\nsufficiently short to excite electron-hole pairs in the MoS2, light\nillumination causes desorption of water and oxygen molecules. The change in the\nmolecular gating provided by the physisorbed molecules is the dominant\ncontribution to the device photoresponse in ambient conditions."
    },
    {
        "anchor": "A mesoscopic Tera-hertz pulse detector: We show that, under the passage of an electromagnetic terahertz pulse, an\nasymmetric double barrier device may act as an on/off current switch, depending\non the bias. The time-dependent response of the device is discussed.",
        "positive": "$\\mathcal{PT}$ symmetry-protected exceptional cones and analogue Hawking\n  radiation: Non-Hermitian Hamiltonians, which effectively describe dissipative systems,\nand analogue gravity models, which simulate properties of gravitational\nobjects, comprise seemingly different areas of current research. Here, we\ninvestigate the interplay between the two by relating parity-time-symmetric\ndissipative Weyl-type Hamiltonians to analogue Schwarzschild black holes\nemitting Hawking radiation. We show that the exceptional points of these\nHamiltonians form tilted cones mimicking the behavior of the light cone of a\nradially infalling observer approaching a black hole horizon. We further\ninvestigate the presence of tunneling processes, reminiscent of those happening\nin black holes, in a concrete example model. We interpret the non-trivial\nresult as the purely thermal contribution to analogue Hawking radiation in a\nSchwarzschild black hole. Assuming that our particular Hamiltonian models a\nphotonic crystal, we discuss the concrete nature of the analogue Hawking\nradiation in this particular setup."
    },
    {
        "anchor": "Classification of topological insulators and superconductors in three\n  spatial dimensions: We systematically study topological phases of insulators and superconductors\n(SCs) in 3D. We find that there exist 3D topologically non-trivial insulators\nor SCs in 5 out of 10 symmetry classes introduced by Altland and Zirnbauer\nwithin the context of random matrix theory. One of these is the recently\nintroduced Z_2 topological insulator in the symplectic symmetry class. We show\nthere exist precisely 4 more topological insulators. For these systems, all of\nwhich are time-reversal (TR) invariant in 3D, the space of insulating ground\nstates satisfying certain discrete symmetry properties is partitioned into\ntopological sectors that are separated by quantum phase transitions. 3 of the\nabove 5 topologically non-trivial phases can be realized as TR invariant SCs,\nand in these the different topological sectors are characterized by an integer\nwinding number defined in momentum space. When such 3D topological insulators\nare terminated by a 2D surface, they support a number (which may be an\narbitrary non-vanishing even number for singlet pairing) of Dirac fermion\n(Majorana fermion when spin rotation symmetry is completely broken) surface\nmodes which remain gapless under arbitrary perturbations that preserve the\ncharacteristic discrete symmetries. In particular, these surface modes\ncompletely evade Anderson localization. These topological phases can be thought\nof as 3D analogues of well known paired topological phases in 2D such as the\nchiral p-wave SC. In the corresponding topologically non-trivial and\ntopologically trivial 3D phases, the wavefunctions exhibit markedly distinct\nbehavior. When an electromagnetic U(1) gauge field and fluctuations of the gap\nfunctions are included in the dynamics, the SC phases with non-vanishing\nwinding number possess non-trivial topological ground state degeneracies.",
        "positive": "Non-Hermitian Skin Effects in Hermitian Correlated/Disordered Systems:\n  Boundary-Sensitive/Insensitive Quantities and Pseudo Quantum Number: There is a common belief in the condensed matter community that bulk\nquantities become insensitive to the boundary condition in the infinite-volume\nlimit. Here we reconsider this statement in terms of recent arguments of\nnon-Hermitian skin effects, -strong dependence of spectra on boundary\nconditions for the non-Hermitian Hamiltonians-, in the traditional Green's\nfunction formalism. We find the criterion for quantities to be\nsensitive/insensitive against the boundary condition in Hermitian\ncorrelated/disordered systems, which is characterized by the residue theorem.\nWe also discuss the uncertainty of the quasiparticle energy under the skin\neffects in terms of nonnormal pseudospectra, which can be tested via the sharp\noptical absorption from the bulk-surface coupling. Our result indicates that\n\"pseudo quantum number\" emerges as a consequence of large nonnormality."
    },
    {
        "anchor": "Ab initio modelling of spin relaxation lengths in disordered graphene\n  nanoribbons\u2020: The spin-dependent transport properties of armchair graphene nanoribbons in\nthe presence of extrinsic spin-orbit coupling induced by a random distribution\nof Nickel adatoms is studied. By combining a recursive Green's function\nformalism with density functional theory, we explore the influence of ribbon\nlength and metal adatom concentration on the conductance. At a given length, we\nobserved a significant enhancement of the spin-flip channel around resonances\nand at energies right above the Fermi level. We also estimate the\nspin-relaxation length, finding values on the order of tens of micrometers at\nlow Ni adatom concentrations. This study is conducted at singular ribbon\nlengths entirely from fully ab-initio methods, providing indirectly evidence\nthat the Dyakonov-Perel spin relaxation mechanism might be the dominant at low\nconcentrations as well as the observation of oscillations in the\nspin-polarization.",
        "positive": "Collective Modes of Quantum Hall Stripes: The collective modes of striped phases in a quantum Hall system are computed\nusing the time-dependent Hartree-Fock approximation. Uniform stripe phases are\nshown to be unstable to the formation of modulations along the stripes, so that\nwithin the Hartree-Fock approximation the groundstate is a stripe crystal. Such\ncrystalline states are generically gapped at any finite wavevector; however, in\nthe quantum Hall system the interactions of modulations among different stripes\nis found to be remarkably weak, leading to an infinite collection of collective\nmodes with immeasurably small gaps. The resulting long wavelength behavior is\nderivable from an elastic theory for smectic liquid crystals. Collective modes\nfor the phonon branch are computed throughout the Brillouin zone, as are spin\nwave and magnetoplasmon modes. A soft mode in the phonon spectrum is identified\nfor partial filling factors sufficiently far from 1/2, indicating a second\norder phase transition. The modes contain several other signatures that should\nbe experimentally observable."
    },
    {
        "anchor": "Liquid-Crystal State of $\u03bd=1/m$ Quantum Hall Effects: At filling factor $\\nu=1/m$, $m$ odd integer, I present variational\nground-state and excited-state wave functions, of two-dimensional electron\nsystem with homogeneous ion background, that show the condensation into a\nliquid-crystal state. For $m=1, 3, 5$, the ground-state energy per electron is\nsubstantially lower than the Laughlin one, for uniform liquid state.",
        "positive": "Atomically inspired $k \\cdot p$ approach and valley Zeeman effect in\n  transition metal dichalcogenide monolayers: We developed a six-band $k \\cdot p$ model that describes the electronic\nstates of monolayer transition metal dichalcogenides (TMDCs) in $K$-valleys.\nThe set of parameters for the $k \\cdot p$ model is uniquely determined by\ndecomposing tight-binding (TB) models in the vicinity of $K^\\pm$-points. First,\nwe used TB models existing in literature to derive systematic parametrizations\nfor different materials, including MoS$_2$, WS$_2$, MoSe$_2$ and WSe$_2$. Then,\nby using the derived six-band $k \\cdot p$ Hamiltonian we calculated effective\nmasses, Landau levels, and the effective exciton $g$-factor $g_{X^0}$ in\ndifferent TMDCs. We showed that TB parameterizations existing in literature\nresult in small absolute values of $g_{X^0}$, which are far from the\nexperimentally measured $g_{X^0} \\approx -4$. To further investigate this issue\nwe derived two additional sets of $k \\cdot p$ parameters by developing our own\nTB parameterizations based on simultaneous fitting of ab-initio calculated,\nwithin the density functional (DFT) and $GW$ approaches, energy dispersion and\nthe value of $g_{X^0}$. We showed that the change in TB parameters, which only\nslightly affects the dispersion of higher conduction and deep valence bands,\nmay result in a significant increase of $|g_{X^0}|$, yielding\nclose-to-experiment values of $g_{X^0}$. Such a high parameter sensitivity of\n$g_{X^0}$ opens a way to further improvement of DFT and TB models."
    },
    {
        "anchor": "Disorder suppression and precise conductance quantization in\n  constrictions of PbTe quantum wells: Conductance quantization was measured in submicron constrictions of PbTe,\npatterned into narrow,12 nm wide quantum wells deposited between\nPb$_{0.92}$Eu$_{0.08}$Te barriers. Because the quantum confinement imposed by\nthe barriers is much stronger than the lateral one, the one-dimensional\nelectron energy level structure is very similar to that usually met in\nconstrictions of AlGaAs/GaAs heterostructures. However, in contrast to any\nother system studied so far, we observe precise conductance quantization in\n$2e^2/h$ units, {\\it despite of significant amount of charged defects in the\nvicinity of the constriction}. We show that such extraordinary results is a\nconsequence of the paraelectric properties of PbTe, namely, the suppression of\nlong-range tails of the Coulomb potentials due to the huge dielectric constant.",
        "positive": "Parametric Luminescence of Microcavity Polaritons: The spectral and dispersive emission properties are analytically determined\nfor the two-dimensional system of exciton-polaritons in microcavities excited\nby a resonant and coherent optical pump. New collective excitations result from\nthe anomalous coupling between one generic polariton state and its idler,\ncreated by the scattering of two pumped polaritons. The corresponding\nparametric correlation is stimulated by the emitter and idler populations and\ndrives very efficiently the luminescence. The intrinsic properties of the\ncollective excitations determine a peculiar emission pattern."
    },
    {
        "anchor": "Intersubband gain in a Bloch oscillator and Quantum cascade laser: The link between the inversion gain of quantum cascade structures and the\nBloch gain in periodic superlattices is presented. The proposed theoretical\nmodel based on the density matrix formalism is able to treat the gain mechanism\nof the Bloch oscillator and Quantum cascade laser on the same footing by taking\ninto account in-plane momentum relaxation. The model predicts a dispersive\ncontribution in addition to the (usual) population-inversion-dependent\nintersubband gain in quantum cascade structures and - in the absence of\ninversion - provides the quantum mechanical description for the dispersive gain\nin superlattices. It corroborates the predictions of the semi-classical\nminiband picture, according to which gain is predicted for photon energies\nlower than the Bloch oscillation frequency, whereas net absorption is expected\nat higher photon energies, as a description which is valid in the\nhigh-temperature limit. A red-shift of the amplified emission with respect to\nthe resonant transition energy results from the dispersive gain contribution in\nany intersubband transition, for which the population inversion is small.",
        "positive": "Electron transport and current fluctuations in short coherent conductors: Employing a real time effective action formalism we analyze electron\ntransport and current fluctuations in comparatively short coherent conductors\nin the presence of electron-electron interactions. We demonstrate that, while\nCoulomb interaction tends to suppress electron transport, it may {\\it strongly\nenhance} shot noise in scatterers with highly transparent conducting channels.\nThis effect of excess noise is governed by the Coulomb gap observed in the\ncurrent-voltage characteristics of such scatterers. We also analyze the\nfrequency dispersion of higher current cumulants and emphasize a direct\nrelation between electron-electron interaction effects and current fluctuations\nin disordered mesoscopic conductors."
    },
    {
        "anchor": "Heat diodes made of quantum dots embedded in nanowires connected to\n  metallic electrodes: The quantum dot arrays (QDAs) embedded into inhomogeneous nanowires connected\nto metallic electrodes show an electron heat rectification effect, which is\nattributed to the thermal voltage arising from a temperature bias and the QDA\nwith a broken spatial inversion symmetry. The staircase energy levels of QDAs\ncan be controlled to the resonant and off resonant transports for electrons in\nthe forward and backward temperature biases, respectively. The effect of\nelectron Coulomb interactions on the rectification efficiency of heat diode is\nclarified by the case of double QDs. We find that it is important to reduce\nphonon heat currents for implementing a high efficient electron heat diode at\nhigh temperature.",
        "positive": "Comment on \"Chiral tunnelling and the Klein paradox in graphene\": Arising from the Article: Nature Phys. 2, 620-625 (2006), By M. I.\nKatsnelson, K. S. Novoselov, and A. K. Geim."
    },
    {
        "anchor": "Edge excitons in a 2D topological insulator in the magnetic field: Exciton edge states and the microwave edge exciton absorption of a 2D\ntopological insulator subject to the in-plane magnetic field are studied. The\nmagnetic field forms a narrow gap in electron edge states that allows the\nexistence of edge exciton. The exciton binding energy is found to be much\nsmaller than the energy of a 1D Coulomb state. Phototransitions exist on the\nexciton states with even numbers, while odd exciton states are dark.",
        "positive": "Transition between continuous and discrete spectra in\n  dynamical-decoupling noise spectroscopy: Here, we explore the prospects of carrying out the single qubit spectroscopy\nof environmental noise when the resolution of the frequency filters produced by\nthe dynamical decoupling pulse sequences can be set high enough to reveal the\ndiscrete structure of the noise spectral density. The standard form of\nspectroscopy is applicable when the filter is unable to resolve the discrete\nspectral lines and only coarse grained approximation of the spectrum is\nrecorded in the qubit's decoherence rate. When the discrete structure becomes\naccessible, the qubit probe evolves in a qualitatively different manner, and\nthe procedure for recovering spectral density has to be redesigned."
    },
    {
        "anchor": "Improved spectral stability in spin transfer nano-oscillators: single\n  vortex versus coupled vortices dynamics: We perform a comparative study of spin transfer induced excitation of the\ngyrotropic motion of a vortex core with either uniform or vortex spin\npolarizers. The microwave output voltage associated with the vortex dynamics,\ndetected in both cases, displays a strong reduction of phase fluctuations in\nthe case of the vortex polarizer, with a decrease of the peak linewidth by one\norder of magnitude down to 200kHz at zero field. A thorough study of rf\nemission features for the different accessible vortex configurations shows that\nthis improvement is related to the excitation of coupled vortex dynamics by\nspin transfer torques.",
        "positive": "Ballistic Graphene Nanoribbon MOSFETs: a full quantum real-space\n  simulation study: A real-space quantum transport simulator for carbon nanoribbon (CNR) MOSFETs\nhas been developed. Using this simulator, the performance of carbon nanoribbon\n(CNR) MOSFETs is examined in the ballistic limit. The impact of quantum effects\non device performance of CNR MOSFETs is also studied. We found that 2D\nsemi-infinite graphene contacts provide metal-induced-gap-states (MIGS) in the\nCNR channel. These states would provide quantum tunneling in the short channel\ndevice and cause Fermi level pining. These effects cause device performance\ndegradation both on the ON-state and the OFF-state. Pure 1D devices (infinite\ncontacts), however, show no MIGS. Quantum tunneling effects are still playing\nan important role in the device characteristics. Conduction due to band-to-band\ntunneling is accurately captured in our simulations. It is important in these\ndevices, and found to dominate the off-state current. Based on our simulations,\nboth a 1.4nm wide and a 1.8nm wide CNR with channel length of 12.5nm can\noutperform ultra scaled Si devices in terms of drive current capabilities and\nelectrostatic control. Although subthreshold slopes in the forward-bias\nconduction are better than in Si transistors, tunneling currents are important\nand prevent the achievement of the theoretical limit of 60mV/dec."
    },
    {
        "anchor": "A note on exclusion statistics parameter and Hausdorff dimension: We obtain for an anyon gas in the high temperature limit a relation between\nthe exclusion statistics parameter $g$ and the Hausdorff dimension $h$, given\nby $g=h(2-h)$. The anyonic excitations are classified into equivalence classes\nlabeled by Hausdorff dimension, $h$, and in that limit, the parameter $g$ give\nus the second virial coefficient for any statistics, $\\nu$. The anyonic\nexcitations into the same class $h$ get the same value of this virial\ncoefficient.",
        "positive": "Electrical transport through a mechanically gated molecular wire: A surface-adsorbed molecule is contacted with the tip of a scanning tunneling\nmicroscope (STM) at a pre-defined atom. On tip retraction, the molecule is\npeeled off the surface. During this experiment, a two-dimensional differential\nconductance map is measured on the plane spanned by the bias voltage and the\ntip-surface distance. The conductance map demonstrates that tip retraction\nleads to mechanical gating of the molecular wire in the STM junction. The\nexperiments are compared with a detailed ab initio simulation. We find that\ndensity functional theory (DFT) in the local density approximation (LDA)\ndescribes the tip-molecule contact formation and the geometry of the molecular\njunction throughout the peeling process with predictive power. However, a\nDFT-LDA-based transport simulation following the non-equilibrium Green's\nfunctions (NEGF) formalism fails to describe the behavior of the differential\nconductance as found in experiment. Further analysis reveals that this failure\nis due to the mean-field description of electron correlation in the local\ndensity approximation. The results presented here are expected to be of general\nvalidity and show that, for a wide range of common wire configurations,\nsimulations which go beyond the mean-field level are required to accurately\ndescribe current conduction through molecules. Finally, the results of the\npresent study illustrate that well-controlled experiments and concurrent ab\ninitio transport simulations that systematically sample a large configuration\nspace of molecule-electrode couplings allow the unambiguous identification of\ncorrelation signatures in experiment."
    },
    {
        "anchor": "Topological braiding of non-Abelian mid-gap defects in classical\n  meta-materials: Non-trivial braid-group representations appear as non-Abelian quantum\nstatistics of emergent Majorana zero modes in one and two-dimensional\ntopological superconductors. Here, we generate such representations with\ntopologically protected domain-wall modes in a classical analogue of the Kitaev\nsuperconducting chain, with a particle-hole like symmetry and a Z2 topological\ninvariant. The mid-gap modes are found to exhibit distinct fusion channels and\nrich non-Abelian braiding properties, which are investigated using a T-junction\nsetup. We employ the adiabatic theorem to explicitly calculate the braiding\nmatrices for one and two pairs of these mid-gap topological defects.",
        "positive": "Impact of MBE-grown (In,Ga)As/GaAs metamorphic buffers on excitonic and\n  optical properties of single quantum dots with single-photon emission tuned\n  to the telecom range: Tuning GaAs-based quantum emitters to telecom wavelengths makes it possible\nto use the existing mature technology for applications in, e.g., long-haul\nultra-secure communication in the fiber networks. A promising method\nre-developed recently is to use a metamorphic InGaAs buffer that redshifts the\nemission by reducing strain. However, the impact of such a buffer causes also a\nsimultaneous modification of other quantum dot properties. Knowledge of these\neffects is crucial for actual implementations of QD-based non-classical light\nsources for quantum communication schemes. Here, we thoroughly study single\nGaAs-based quantum dots grown by molecular-beam epitaxy on specially designed,\ndigital-alloy InGaAs metamorphic buffers. With a set of structures varying in\nthe buffer indium content and providing quantum dot emission through the\ntelecom spectral range up to 1.6 $\\mu$m, we analyze the impact of the buffer\nand its composition on QD structural and optical properties. We identify the\nmechanisms of quantum dot emission shift with varying buffer composition. We\nalso look into the charge trapping processes and compare excitonic properties\nfor different growth conditions with single-dot emission successfully shifted\nto both, the second and the third telecom windows."
    },
    {
        "anchor": "Mechanical Flip-Chip for Ultra-High Electron Mobility Devices: Electrostatic gates are of paramount importance for the physics of devices\nbased on high-mobility two-dimensional electron gas (2DEG) since they allow\ndepletion of electrons in selected areas. This field-effect gating enables the\nfabrication of a wide range of devices such as, for example, quantum point\ncontacts (QPC), electron interferometers and quantum dots. To fabricate these\ngates, processing is usually performed on the 2DEG material, which is in many\ncases detrimental to its electron mobility. Here we propose an alternative\nprocess which does not require any processing of the 2DEG material other than\nfor the ohmic contacts. This approach relies on processing a separate wafer\nthat is then mechanically mounted on the 2DEG material in a flip-chip fashion.\nThis technique proved successful to fabricate quantum point contacts on both\nGaAs/AlGaAs materials with both moderate and ultra-high electron mobility.",
        "positive": "Universal voltage scaling due to self-averaging of the quantum\n  corrections in graphene: The differential conductance of graphene is shown to exhibit a zero-bias\nanomaly at low temperatures, arising from a suppression of the quantum\ncorrections due to weak localization and electron interactions. A simple\nrescaling of these data, free of any adjustable parameters, shows that this\nanomaly exhibits a universal, temperature- ($T$) independent form. According to\nthis, the differential conductance is approximately constant at small voltages\n($V<k_BT/e$), while at larger voltages it increases logarithmically with the\napplied bias, reflecting a quenching of the quantum corrections. For\ntheoretical insight into the origins of this behavior, we formulate a model for\nweak-localization in the presence of nonlinear transport. According to this,\nthe voltage applied under nonequilibrium induces unavoidable dephasing, arising\nfrom a self-averaging of the diffusing electron waves responsible for\ntransport. By establishing the manner in which the quantum corrections are\nsuppressed in graphene, our study will be of broad relevance to the\ninvestigation of nonequilibrium transport in mesoscopic systems in general.\nThis includes systems implemented from conventional metals and semiconductors,\nas well as those realized using other two-dimensional semiconductors and\ntopological insulators."
    },
    {
        "anchor": "Statistics of orbital entanglement production in quantum-chaotic dots: The production of orbitally entangled electrons in quantum-chaotic dots is\ninvestigated from a statistical point of view. The degree of entanglement is\nquantified through the concurrence and the entanglement of formation. We\ncalculate the complete statistical distributions of the entanglement measures\nby using random matrix theory. Simple analytical expressions are provided for\nthe concurrence distributions. We identify clear signatures of time-reversal\ninvariance in the production of entanglement at the level of the\nentanglement-measure distributions, such as the ability of producing maximally\nentangled (Bell) states, which passed unnoticed in previous works where only\nthe first two moments of the distributions were studied.",
        "positive": "Spin waves scattering on a Bloch point: We show that, after a transformation, the dynamics of linear perturbations\n(spin waves) around a singular Bloch point soliton is formally equivalent to a\nquantum system of an electron in a magnetic monopole field. The analytical\nsolution to this problem is known and allows us to find the spectrum and the\nscattering of a wave in a Bloch point field."
    },
    {
        "anchor": "Evaluation of the Bychkov- Rashba Field from the Spin Resonance of\n  Electrons in a Si Quantum Well: From spin resonance of two-dimensional (2D) conduction electrons in a\nmodulation doped SiGe/Si/SiGe quantum well structure we find a 2D anisotropy of\nboth the line broadening (dephasing time) and the g-factor. We show that these\ncan be explained consistently in terms of the Bychkov-Rashba (BR) field which\nhere is the dominant coupling between electron motion and spin. We obtain a BR\nparameter of alpha = 1.1 e-12 eV cm - three orders of magnitude smaller as\ncompared to III-V wells. Extrapolating for low electron concentrations we\nobtain a g-factor of the Si conduction band of 2.00073+/-0.00010.",
        "positive": "Microscopic verification of topological electron-vortex binding in the\n  lowest-Landau-level crystal state: When two-dimensional electrons are subjected to a very strong magnetic field,\nthey are believed to form a triangular Wigner crystal. We demonstrate that, in\nthe entire crystal phase, this crystal is very well represented by a\ncomposite-fermion-crystal wave function, revealing that it is not a simple\nHartree-Fock crystal of electrons but an inherently quantum mechanical crystal\ncharacterized by a non-perturbative binding of quantized vortices to electrons,\nwhich establishes a long range quantum coherence in it. It is suggested that\nthis has qualitative consequences for experiment."
    },
    {
        "anchor": "Acoustic metasurfaces for scattering-free anomalous reflection and\n  refraction: Manipulation of acoustic wavefronts by thin and planar devices, known as\nmetasurfaces, has been extensively studied, in view of many important\napplications. Reflective and refractive metasurfaces are designed using the\ngeneralized reflection and Snell's laws, which tell that local phase shifts at\nthe metasurface supply extra momentum to the wave, presumably allowing\narbitrary control of reflected or transmitted waves. However, as it has been\nrecently shown for the electromagnetic counterpart, conventional metasurfaces\nbased on the generalized laws of reflection and refraction have important\ndrawbacks in terms of power efficiency. This work presents a new synthesis\nmethod of acoustic metasurfaces for anomalous reflection and transmission that\novercomes the fundamental limitations of conventional designs, allowing full\ncontrol of acoustic energy flow. The results show that different mechanisms are\nnecessary in the reflection and transmission scenarios for ensuring perfect\nperformance. Metasurfaces for anomalous reflection require non-local response,\nwhich allows energy channeling along the metasurface. On other hand, for\nperfect manipulation of anomalously transmitted waves, local and non-symmetric\nresponse is required. These conclusions are interpreted through appropriate\nsurface impedance models which are used to find possible physical\nimplementations of perfect metasurfaces in each scenario. We hope that this\nadvance in the design of acoustic metasurfaces opens new avenues not only for\nperfect anomalous reflection and transmission but also for realizing more\ncomplex functionalities, such as focusing, self-bending or vortex generation.",
        "positive": "Tunneling phase diagrams in anisotropic Multi-Weyl semimetals: Motivated by the exciting prediction of Multi-Weyl topological semimetals\nthat are stabilized by point group symmetries [Phys. Rev. Lett. 108 (2012)\n266802], we study tunneling phenomena for a class of anisotropic Multi-Weyl\nsemimetals. We find that a distant detector for different ranges of an\nanisotropy parameter $\\lambda$ and incident angle $\\theta$ will measure a\ndifferent number of propagating transmitted modes. We present these findings in\nterms of phase diagrams that is valid for an incoming wave with fixed\nwavenumber $k$--energy is not fixed. To gain a deeper understanding of this\nphenomenon we then focus on the simplest case of an anisotropic quadratic\nWeyl-semimetal and analyze tunneling coefficients analytically and numerically\nto confirm the observations from the phase diagram. Our results show\nnon-analytical behavior, which is the hallmark of a phase transition. This\nserves as a motivation to make a formal analogy with phase transitions that are\nknown from statistical mechanics. Specifically, we argue that the long distance\nlimit in our tunneling problem takes the place of the thermodynamic limit in\nstatistical mechanics. More precisely, find a direct formal connection to the\nrecently developed formalism for dynamical phase transitions [Reports on\nProgress in Physics 81 (5) (2018) 054001]. We propose that this analogy to\nphase transitions can help classify transport properties in exotic semimetals."
    },
    {
        "anchor": "Characterization of highly crystalline lead iodide nanosheets prepared\n  by room-temperature solution processing: Two-dimensional semiconducting materials are particularly appealing for many\napplications. Although theory predicts a large number of two-dimensional\nmaterials, experimentally only a few of these materials have been identified\nand characterized comprehensively in the ultrathin limit. Lead iodide, which\nbelongs to the transition metal halides family and has a direct bandgap in the\nvisible spectrum, has been known for a long time and has been well\ncharacterized in its bulk form. Nevertheless, studies of this material in the\nnanometer thickness regime are rather scarce. In this article we demonstrate an\neasy way to synthesize ultrathin, highly crystalline flakes of PbI2 by\nprecipitation from a solution in water. We thoroughly characterize the produced\nthin flakes with different techniques ranging from optical and Raman\nspectros-copy to temperature-dependent photoluminescence and electron\nmicroscopy. We compare the results to ab initio calculations of the band\nstructure of the material. Finally, we fabricate photodetectors based on PbI2\nand study their optoelectronic properties.",
        "positive": "Coupled Yu-Shiba-Rusinov states induced by a many-body molecular spin on\n  a superconductor: A magnetic impurity on a superconductor induces Yu-Shiba-Rusinov (YSR) bound\nstates, detected by tunneling spectroscopy as long-lived quasiparticle\nexcitations inside the superconducting gap. Coupled YSR states constitute basic\nelements to engineer artificial superconducting states, but their\nsubstrate-mediated interactions are generally weak. In this paper, we report\nthat intramolecular (Hund's like) exchange interactions produce coupled YSR\nstates across a molecular platform. We measured YSR spectra along a magnetic\niron-porphyrin on Pb(111) and found evidences of two orbital interaction\nchannels, which invert their particle-hole asymmetry across the molecule.\nNumerical calculations show that the identical YSR asymmetry pattern of the two\nchannels is caused by two spin-hosting orbitals with opposite potential\nscattering and coupled strongly. Both channels can be similarly excited by\ntunneling electrons into each orbital, depicting a new scenario for entangled\nsuperconducting bound states using molecular platforms."
    },
    {
        "anchor": "A Field Theory for Partially Polarized Quantum Hall States: We propose a new effective field theory for partially polarized quantum Hall\nstates. The density and polarization for the mean field ground states are\ndetermined by couplings to two Chern-Simons gauge fields. In addition there is\na $\\sigma$-model field, $\\mh$, which is necessary both to preserve the\nChern-Simons gauge symmetry that determines the correlations in the ground\nstate, and the global SU(2) invariance related to spin rotations. For states\nwith non zero polarization, the low energy dynamics is that of a ferromagnet.\nIn addition to spin waves, the spectrum contains topological solitons, or\nskyrmions, just as in the fully polarized case. The electric charge of the\nskyrmions is given by $Q_{el}=\\nu P Q_{top}$, where $\\nu$ is the filling\nfraction, $P$ the magnitude of the polarization, and $Q_{top}$ the topological\ncharge. For the special case of full polarization, the theory involves a single\nscalar field and a single Chern-Simons field in addition to the $\\sigma$-model\nfield, $\\mh$. We also give a heuristic derivation of the model lagrangians for\nboth full and partial polarization, and show that in a mean field picture, the\nfield $\\mh$ is necessary in order to take into account the Berry phases\noriginating from rotations of the electron spins.",
        "positive": "Doubling Theorem and Boundary States of Five-Dimensional Weyl Semimetal: We study the generic band structures of the five-dimensional (5D) Weyl\nsemimetal, in which the band degeneracies are 2D Weyl surfaces in the momentum\nspace, and may have non-trivial linkings with each other if they carry nonzero\nsecond Chern numbers. We prove a number of theorems constraining the\ntopological linking configurations of the Weyl surfaces, which can be viewed as\na 5D generalization of the celebrated Doubling Theorem for 3D Weyl semimetal.\nAs a direct physical consequence of these constraints, the 5D Weyl semimetal\nhosts a rich structure of topological boundary states. We show that on the 4D\nboundary of the 5D Weyl semimetal, there are 3D chiral Fermi hypersurfaces\nprotected by bulk Weyl surfaces. On top of that, for bulk Weyl surfaces that\nare linked and carry nonzero second Chern numbers, the associated boundary 3D\nFermi hypersurfaces will shrink to singularities at certain energies, which\ntrace out a protected 1D Weyl nodal arc, in analogy to the Fermi arc on the 3D\nWeyl semimetal surface."
    },
    {
        "anchor": "Counting statistics and detector properties of quantum point contacts: Quantum detector properties of the quantum point contact (QPC) are analyzed\nfor arbitrary electron transparency and coupling strength to the measured\nsystem and are shown to be determined by the electron counting statistics.\nConditions of the quantum-limited operation of the QPC detector which prevent\ninformation loss through the scattering time and scattering phases are found\nfor arbitrary coupling. We show that the phase information can be restored and\nused for the quantum-limited detection by inclusion of the QPC detector in the\nelectronic Mach-Zehnder interferometer.",
        "positive": "The nuclear polaron beyond the mean-field approximation: In III-V semiconductors it was shown theoretically that under optical cooling\nthe nuclear spin polaron bound to neutral donors would form below some critical\nnuclear spin temperature TC [I. A. Merkulov, Phys. Solid State 40, 930 (1998)].\nThe predicted critical behavior is a direct consequence of the use of the\nmean-field approximation. It is known however that in any finite size system a\ncritical behavior must be absent. Here we develop a model of the optically\ncooled nuclear polaron, which goes beyond the mean-field approximation. An\nexpression of the generalized free energy of the optically cooled nuclear\npolaron, valid for a finite, albeit large, number of spins, is derived. This\nmodel permits to describe the continuous transition from the fluctuation\ndominated regime to the saturation regime, as the nuclear spin temperature\ndecreases. It is shown that due to the finite number of nuclear spins involved\nin the polaron, the critical effects close to TC are smoothed by the spin\nfluctuations. Particularly, instead of a divergence, the nuclear spin\nfluctuations exhibit a sharp peak at TC, before being depressed well below TC.\nInterestingly, the formation of the nuclear polaron can, in certain conditions,\nboost the nuclear polarization beyond the value obtained solely by optical\npumping. Finally, we suggest that the nuclear polaron could be detected by spin\nnoise spectroscopy or via its superparamagnetic behavior."
    },
    {
        "anchor": "Impurity-induced triple point fermions in twisted bilayer graphene: Triple point fermions are elusive electronic excitations that generalize\nDirac and Weyl modes beyond the conventional high energy paradigm. Yet, finding\nreal materials naturally hosting these excitations at the Fermi energy has\nremained challenging. Here we show that twisted bilayer graphene is a versatile\nplatform to realize robust triple point fermions in two dimensions. In\nparticular, we establish that the introduction of localized impurities lifts\none of the two degenerate Dirac cones, yielding triple point fermions at charge\nneutrality. Furthermore, we show that the valley polarization is preserved for\ncertain impurity locations in the moire supercell for both weak and strong\nimpurity potentials. We finally show that in the presence of interactions, a\nsymmetry broken state with local magnetization can develop out of the triple\npoint bands, which can be selectively controlled by electrostatic gating. Our\nresults put forward twisted bilayer graphene as a simple solid-state platform\nto realize triple point fermions at charge neutrality, and demonstrate the\nnon-trivial role of impurities in moire systems.",
        "positive": "Reply to Simon's Comment on \"Evidence for an Anisotropic State of\n  Two-Dimensional Electrons in High Landau Levels\": We recently reported [PRL 82, 394 (1999)] large transport anisotropies in a\ntwo-dimensional electron gas in high Landau levels. These observations were\nmade utilizing both square and Hall bar sample geometries. Simon recently\ncommented [cond-mat/9903086] that a classical calculation of the current flow\nin the sample shows a magnification of an underlying anisotropy when using a\nsquare sample. In this reply we present more recent data obtained with a very\nhigh mobility sample, and reiterate that, with or without magnification, an\nanisotropic state develops in high Landau levels at very low temperatures."
    },
    {
        "anchor": "Switching induced by spin Hall effect in an in-plane magnetized\n  ferromagnet with the easy axis parallel to the current: Magnetization switching in a fine-structured ferromagnet of nanoscale by the\nspin-transfer torque excited via the spin Hall effect has attracted much\nattention because it enables us to manipulate the magnetization without\ndirectly applying current to the ferromagnet. However, the switching mechanism\nis still unclear in regard to the ferromagnet having an in-plane easy axis\nparallel to the current. Here, we develop an analytical theory of the\nmagnetization switching in this type of ferromagnet, and reveal the threshold\ncurrent formulas for a deterministic switching. It is clarified that the\ncurrent should be in between a certain range determined by two threshold\ncurrents because the spin-transfer torque due to a large current outside the\nrange brings the magnetization in an energetically unstable state, and causes\nmagnetization precession around the hard axis.",
        "positive": "Semiconducting Monolayer Materials as a Tunable Platform for Excitonic\n  Solar Cells: The recent advent of two-dimensional monolayer materials with tunable\noptoelectronic properties and high carrier mobility offers renewed\nopportunities for efficient, ultra-thin excitonic solar cells alternative to\nthose based on conjugated polymer and small molecule donors. Using\nfirst-principles density functional theory and many-body calculations, we\ndemonstrate that monolayers of hexagonal BN and graphene (CBN) combined with\ncommonly used acceptors such as PCBM fullerene or semiconducting carbon\nnanotubes can provide excitonic solar cells with tunable absorber gap,\ndonor-acceptor interface band alignment, and power conversion efficiency, as\nwell as novel device architectures. For the case of CBN-PCBM devices, we\npredict the limit of power conversion efficiencies to be in the 10 - 20% range\ndepending on the CBN monolayer structure. Our results demonstrate the\npossibility of using monolayer materials in tunable, efficient, polymer-free\nthin-film solar cells in which unexplored exciton and carrier transport regimes\nare at play."
    },
    {
        "anchor": "Voltage-triggered Ultra-fast Metal-insulator Transition in Vanadium\n  Dioxide Switches: Electrically driven metal-insulator transition in vanadium dioxide (VO2) is\nof interest in emerging memory devices, neural computation, and high speed\nelectronics. We report on the fabrication of out-of-plane VO2\nmetal-insulator-metal (MIM) structures and reproducible high-speed switching\nmeasurements in these two-terminal devices. We have observed a clear\ncorrelation between electrically-driven ON/OFF current ratio and\nthermally-induced resistance change during metal-insulator transition. It is\nalso found that sharp metal-insulator transition could be triggered by external\nvoltage pulses within 2 ns at room temperature and the achieved ON/OFF ratio is\ngreater than two orders of magnitude with good endurance.",
        "positive": "Vortex wake patterns in superfluid $^{4}He$: Excitations in the form of quantized vortex rings are known to exist in\nsuperfluid $^{4}He$ at energies and momenta exceeding those of the Landau\nphonon-roton spectrum. They form a vortex branch of elementary excitations\nspectrum which is disconnected from the Landau spectrum. Interference of vortex\nring excitations determines wake patterns due to uniformly traveling sources in\nbulk superfluid at low speeds and pressures. The dispersion law of these\nexcitations resembles that of gravity waves on deep water with infrared wave\nnumber cutoff. As a result, vortex wake patterns featuring elements of the\nKelvin ship wake are predicted. Specifically, at lowest speeds the pattern with\nfully developed transverse and diverging wavefronts is present. At intermediate\nspeeds transverse wavefronts are absent within a cone whose opening angle\nincreases with the source velocity. At largest speeds only diverging wavefronts\nconfined within a cone whose opening angle decreases with the source velocity\nare found. When experimentally observed, these changes in appearance of wake\npatterns serve as indicators of the beginning part of the vortex branch of\nelementary excitations."
    },
    {
        "anchor": "One-Dimensional Quantum Confinement Effect Modulated Thermoelectric\n  Properties in InAs Nanowires: We report electrical conductance and thermopower measurements on InAs\nnanowires synthesized by chemical vapor deposition. Gate modulation of the\nthermopower of individual InAs nanowires with diameter around 20nm is obtained\nover T=40 to 300K. At low temperatures (T< ~100K), oscillations in the\nthermopower and power factor concomitant with the stepwise conductance\nincreases are observed as the gate voltage shifts the chemical potential of\nelectrons in InAs nanowire through quasi-one-dimensional (1D) sub-bands. This\nwork experimentally shows the possibility to modulate semiconductor nanowire's\nthermoelectric properties through the peaked 1D electronic density of states in\nthe diffusive transport regime, a long-sought goal in nanostructured\nthermoelectrics research. Moreover, we point out the importance of scattering\n(or disorder) induced energy level broadening in smearing out the 1D\nconfinement enhanced thermoelectric power factor at practical temperatures\n(e.g. 300K).",
        "positive": "Aharonov-Bohm interference in topological insulator nanoribbons: Topological insulators represent novel phases of quantum matter with an\ninsulating bulk gap and gapless edges or surface states. The two-dimensional\ntopological insulator phase was predicted in HgTe quantum wells and confirmed\nby transport measurements. Recently, Bi2Se3 and related materials have been\nproposed as three-dimensional topological insulators with a single Dirac cone\non the surface and verified by angle-resolved photoemission spectroscopy\nexperiments. Here, we show unambiguous transport evidence of topological\nsurface states through periodic quantum interference effects in layered\nsingle-crystalline Bi2Se3 nanoribbons. Pronounced Aharonov-Bohm oscillations in\nthe magnetoresistance clearly demonstrate the coverage of two-dimensional\nelectrons on the entire surface, as expected from the topological nature of the\nsurface states. The dominance of the primary h/e oscillation and its\ntemperature dependence demonstrate the robustness of these electronic states.\nOur results suggest that topological insulator nanoribbons afford novel\npromising materials for future spintronic devices at room temperature."
    },
    {
        "anchor": "Nanometric Turing Patterns: Morphogenesis of a Bismuth Monolayer: Turing's reaction-diffusion theory of morphogenesis has been very successful\nin understanding macroscopic patterns within complex objects ranging from\nbiological systems to sand dunes. However, this mechanism was never tested\nagainst patterns that emerge at the atomic scale, where the basic ingredients\nare subject to constraints imposed by quantum mechanics. Here we report\nevidence of a Turing pattern that appears in a strained atomic bismuth\nmonolayer assembling on the surface of NbSe$_2$ subject to interatomic\ninteractions and respective kinetics. The narrow range of microscopic\nparameters reflected in numerical analysis that observe stripe patterns and\ndomain walls with Y-shaped junctions is a direct consequence of the\nquantum-mechanically allowed bond-lengths and bond-angles. This is therefore\nthe first demonstration of a dynamically formed Turing pattern at the atomic\nscale.",
        "positive": "Magnetic Skyrmion Annihilation by Quantum Mechanical Tunneling: Magnetic skyrmions are nano-scale magnetic states that could be used in\nvarious spintronics devices. A central issue is the mechanism and rate of\nvarious possible annihilation processes and the lifetime of metastable\nskyrmions. While most studies have focused on classical over-the-barrier\nmechanism for annihilation, it is also possible that quantum mechanical\ntunneling through the energy barrier takes place. Calculations of the lifetime\nof magnetic skyrmions in a two-dimensional lattice are presented and the rate\nof tunneling compared with the classical annihilation rate. A remarkably strong\nvariation in the crossover temperature and the lifetime of the skyrmion is\nfound as a function of the values of parameters in the extended Heisenberg\nHamiltonian, i.e. the out-of-plane anisotropy, Dzyaloshinskii-Moriya\ninteraction (DMI) and applied magnetic field. Materials parameters and\nconditions are identified where the onset of tunneling could be observed on a\nlaboratory time scale. In particular, it is predicted that skyrmion tunneling\ncould be observed in the PdFe/Ir(111) system when an external magnetic field on\nthe order of 6 T is applied."
    },
    {
        "anchor": "Broken symmetry, excitons, gapless modes and topological excitations in\n  Trilayer Quantum Hall systems: We study the interlayer coherent incompressible phase in Trilayer Quantum\nHall systems (TLQH) at total filling factor $ \\nu_{T}=1 $ from three\napproaches:\n  Mutual Composite Fermion (MCF), Composite Boson (CB) and wavefunction\napproach.\n  Just like in Bilayer Quantum Hall system, CB approach is superior than\n  MCF approach in studying TLQH with broken symmetry. The Hall and Hall drag\nresistivities are found to be quantized at $ h/e^{2} $. Two neutral gapless\nmodes with linear dispersion relations are identified and the ratio of the two\nvelocities is close to $ \\sqrt{3} $.\n  The novel excitation spectra are classified into two classes: Charge neutral\nbosonic\n  2-body bound states and Charge $ \\pm 1 $ fermionic 3-body bound states.\n  In general, there are two 2-body Kosterlize-Thouless (KT) transition\ntemperatures and one 3-body KT transition. The Charge $ \\pm 1 $ 3-body\nfermionic bound states may be the main dissipation source of transport\nmeasurements.\n  The broken symmetry in terms of $ SU(3) $ algebra is studied. The structure\nof excitons and their flowing patterns are given. The coupling between the two\nGoldstone modes may lead to the broadening in the zero-bias peak in the\ninterlayer correlated tunnelings of the TLQH. Several interesting features\nunique to TLQH are outlined.\n  Limitations of the CB approach are also pointed out.",
        "positive": "Theory of Optical Transmission through Elliptical Nanohole Arrays: We present a theory which explains (in the quasistatic limit) the\nexperimentally observed [R. Gordon, {\\it et al}, Phys. Rev. Lett. {\\bf 92},\n037401 (2004)] squared dependence of the depolarization ratio on the aspect\nratio of the holes, as well as other features of extraordinary light\ntransition. We calculated the effective dielectric tensor of a metal film\npenetrated by elliptical cylindrical holes and found the extraordinarily light\ntransmission at special frequencies related to the surface plasmon resonances\nof the composite film. We also propose to use the magnetic field for getting a\nstrong polarization effect, which depends on the ratio of the cyclotron to\nplasmon frequencies."
    },
    {
        "anchor": "Dielectric environment mediated quantum screening of one dimensional\n  electron gas: Relaxing the assumption of \"infinite and homogenous background\" the\ndielectric response function of one-dimensional (1D) semiconducting nanowires\nembedded in a dielectric environment is calculated. It is shown that high-k\n(higher than semiconductor dielectric constant) dielectric environment reduces\nthe screening by the free carriers inside the nanostructure whereas, low\ndielectric environment increases the Coulombic interaction between free\ncarriers and enhances the strength of screening function. In long wavelength\nlimit, dielectric screening and collective excitation of electron gas are found\nto be solely determined by the environment instead of the semiconductor.\nBehavior of static dielectric function is particularly addressed at a specific\nwavevector q=2k_F; a wavevector ubiquitously appears in charge transport in\nnanostructures",
        "positive": "Entanglement of two qubits mediated by one-dimensional plasmonic\n  waveguides: We investigate qubit-qubit entanglement mediated by plasmons supported by\none-dimensional waveguides. We explore both the situation of spontaneous\nformation of entanglement from an unentangled state and the emergence of driven\nsteady-state entanglement under continuous pumping. In both cases, we show that\nlarge values for the concurrence are attainable for qubit-qubit distances\nlarger than the operating wavelength by using plasmonic waveguides that are\ncurrently available."
    },
    {
        "anchor": "Performance Assessment of Resonantly Driven Silicon Two-Qubit Quantum\n  Gate: Two-qubit quantum gates play an essential role in quantum computing, whose\noperation critically depends on the entanglement between two qubits. Resonantly\ndriven controlled-NOT (CNOT) gates based on silicon double quantum dots (DQDs)\nare studied theoretically. The physical mechanisms for effective gate\nmodulation of the exchange coupling between two qubits are elucidated. Scaling\nbehaviors of the singlet-triplet energy split, gate-switching speed, and gate\nfidelity are investigated as a function of the quantum dot spacing and\nmodulation gate voltage. It is shown that the entanglement strength and\ngate-switching speed exponentially depend on the quantum dot spacing. A small\nspacing of ~10nm can promise a CNOT gate delay of <1 ns and reliable gate\nswitching in the presence of decoherence. The results show promising\nperformance potential of the resonantly driven two-qubit quantum gates based on\naggressively scaled silicon DQDs.",
        "positive": "Magnitude and Spatial Distribution Control of the Supercurrent in\n  Bi2O2Se-Based Josephson Junction: Many proposals in exploring topological quantum computation are based on\nsuperconducting quantum devices constructed on materials with strong spin-orbit\ncoupling (SOC). For these devices, a full control on both the magnitude and the\nspatial distribution of the supercurrent would be highly demanded, but has been\nelusive up to now. We constructed proximity-type Josephson junction on\nnanoplates of Bi2O2Se, a new emerging semiconductor with strong SOC. Through\nelectrical gating, we show that the supercurrent can be fully turned ON and\nOFF, and its real-space pathways can be configured either through the bulk or\nalong the edges. Our work demonstrates Bi2O2Se as a promising platform for\nconstructing multifunctional hybrid superconducting devices as well as for\nsearching for topological superconductivity."
    },
    {
        "anchor": "Spin-Hall Conductivity in Electron-Phonon Coupled Systems: We derive the ac spin-Hall conductivity $\\sigma_{\\rm sH}(\\omega)$ of\ntwo-dimensional spin-orbit coupled systems interacting with dispersionless\nphonons of frequency $\\omega_0$. For the linear Rashba model we show that the\nelectron-phonon contribution to the spin-vertex corrections breaks the\nuniversality of $\\sigma_{\\rm sH}(\\omega)$ at low-frequencies and provides a\nnon-trivial renormalization of the interband resonance. On the contrary, in a\ngeneralized Rashba model for which the spin-vertex contributions are absent,\nthe coupling to the phonons enters only through the self-energy, leaving the\nlow frequency behavior of $\\sigma_{\\rm sH}(\\omega)$ unaffected by the\nelectron-phonon interaction.",
        "positive": "Controlled dephasing of an electron interferometer with a path detector\n  at equilibrium: Controlled dephasing of electrons, via 'which path' detection, involves, in\ngeneral, coupling a coherent system to a current driven noise source. However,\nhere, we present a case in which a nearly isolated electron puddle at thermal\nequilibrium strongly affects the coherence of a nearby electronic\ninterferometer. Moreover, for certain average electron occupations of the\npuddle, the interferometer exhibits complete dephasing. This robust phenomenon\nstems from the Friedel Sum Rule, which relates a system's occupation with its\nscattering phases. The interferometer opens a peeping window into physics of\nthe isolated electron puddle, which cannot be accessed otherwise."
    },
    {
        "anchor": "Coherent manipulation of single electron spins with Landau-Zener sweeps: We propose a novel method to manipulate the state of a single electron spin\nin a semiconductor quantum dot (QD). The manipulation is achieved by tunnel\ncoupling a QD, labeled $L$, and occupied with an electron to an adjacent QD,\nlabeled $R$, which is not occupied by an electron but having an energy linearly\nvarying in time. We identify a parameter regime in which a complete population\ntransfer between the spin eigenstates $|L\\uparrow\\rangle$ and\n$|L\\downarrow\\rangle$ is achieved without occupying the adjacent QD. This\nmethod is convenient due to the fact that manipulation can be done\nelectrically, without the precise knowledge of the spin resonance condition,\nand is robust against Zeeman level broadening caused by nuclear spins.",
        "positive": "Severe Dirac Mass Gap Suppression in Sb_2Te_3-based Quantum Anomalous\n  Hall Materials: Quantum anomalous Hall (QAH) effect appears in ferromagnetic topological\ninsulators (FMTI) when a Dirac mass gap opens in the spectrum of the\ntopological surface states (SS). Unaccountably, although the mean mass gap can\nexceed 28 meV (or ~320 K), the QAH effect is frequently only detectable at\ntemperatures below 1 K. Using atomic-resolution Landau level spectroscopic\nimaging, we compare the electronic structure of the archetypal FMTI\nCr_0.08(Bi_0.1Sb_0.9)_1.92Te_3 to that of its non-magnetic parent\n(Bi_0.1Sb_0.9)_2Te_3, to explore the cause. In (Bi_0.1Sb_0.9)_2Te_3, we find\nspatially random variations of the Dirac energy. Statistically equivalent Dirac\nenergy variations are detected in Cr_0.08(Bi_0.1Sb_0.9)_1.92Te_3 with\nconcurrent but uncorrelated Dirac mass gap disorder. These two classes of SS\nelectronic disorder conspire to drastically suppress the minimum mass gap to\nbelow 100 {\\mu}eV for nanoscale regions separated by <1 {\\mu}m. This\nfundamentally limits the fully quantized anomalous Hall effect in\nSb_2Te_3-based FMTI materials to very low temperatures."
    },
    {
        "anchor": "Electric and magnetic fields effects on the excitonic properties of\n  elliptic core-multishell quantum wires: The effect of eccentricity distortions of core-multishell quantum wires on\ntheir electron, hole and exciton states is theoretically investigated. Within\nthe effective mass approximation, the Schrodinger equation is numerically\nsolved for electrons and holes in systems with single and double radial\nheterostructures, and the exciton binding energy is calculated by means of a\nvariational approach. We show that the energy spectrum of a core-multishell\nheterostructure with eccentricity distortions, as well as its magnetic field\ndependence, are very sensitive to the direction of an externally applied\nelectric field, an effect that can be used to identify the eccentricity of the\nsystem. For a double heterostructure, the eccentricities of the inner and outer\nshells play an important role on the excitonic binding energy, specially in the\npresence of external magnetic fields, and lead to drastic modifications in the\noscillator strength.",
        "positive": "The Amplitude of Non-Equilibrium Quantum Interference in Metallic\n  Mesoscopic Systems: We study the influence of a DC bias voltage V on quantum interference\ncorrections to the measured differential conductance in metallic mesoscopic\nwires and rings. The amplitude of both universal conductance fluctuations (UCF)\nand Aharonov-Bohm effect (ABE) is enhanced several times for voltages larger\nthan the Thouless energy. The enhancement persists even in the presence of\ninelastic electron-electron scattering up to V ~ 1 mV. For larger voltages\nelectron-phonon collisions lead to the amplitude decaying as a power law for\nthe UCF and exponentially for the ABE. We obtain good agreement of the\nexperimental data with a model which takes into account the decrease of the\nelectron phase-coherence length due to electron-electron and electron-phonon\nscattering."
    },
    {
        "anchor": "Electromechanical properties of freestanding graphene functionalized\n  with tin oxide (SnO2) nanoparticles: Freestanding graphene membranes were functionalized with SnO2 nanoparticles.\nA detailed procedure providing uniform coverage and chemical synthesis is\npresented. Elemental composition was determined using scanning electron\nmicroscopy combined with energy dispersive X-ray analysis. A technique called\nelectrostatic-manipulation scanning tunneling microscopy was used to probe the\nelectromechanical properties of functionalized freestanding graphene samples.\nWe found ten times larger movement perpendicular to the plane compared to\npristine freestanding graphene, and propose a nanoparticle encapsulation model.",
        "positive": "Enhancement of thermoelectric performance in Graphene/BN\n  heterostructures: The thermoelectric properties of in plane heterostructures made of Graphene\nand hexagonal Boron Nitride (BN) have been investigated by means of atomistic\nsimulation. The heterostructures consist in armchair graphene nanoribbons to\nthe sides of which BN flakes are periodically attached. This arrangement\ngenerates a strong mismatch of phonon modes between the different sections of\nthe ribbons, which leads to a very small phonon conductance, while the electron\ntransmission is weakly affected. In combination with the large Seebeck\ncoefficient resulting from the BN-induced bandgap opening or broadening, it is\nshown that large thermoelectric figure of merit ZT > 0.8 can be reached in\nperfect structures at relatively low Fermi energy, depending on the graphene\nnanoribbon width. The high value ZT = 1.48 may even be achieved by introducing\nappropriately vacancies in the channel, as a consequence of further degradation\nof the phonon conductance."
    },
    {
        "anchor": "Spin hydrodynamics in amorphous magnets: Spin superfluidity, i.e., coherent spin transport mediated by topologically\nstable textures, is limited by parasitic anisotropies rooted in relativistic\ninteractions and spatial inhomogeneities. Since structural disorder in\namorphous magnets can average out the effect of these undesired couplings, we\npropose this class of materials as platforms for superfluid spin transport. We\nestablish nonlinear equations describing the hydrodynamics of spin in\ninsulating amorphous magnets, where the currents are defined in terms of\ncoherent rotations of a noncollinear texture. Our theory includes dissipation\nand nonequilibrium torques at the interface with metallic reservoirs. This\nframework allows us to determine different regimes of coherent dynamics and\ntheir salient features in nonlocal magneto-transport measurements. Our work\npaves the way for future studies on macroscopic spin dynamics in materials with\nfrustrated interactions.",
        "positive": "From dissipative dynamics to studies of heat transfer at the nanoscale: We study in a unified manner the dissipative dynamics and the transfer of\nheat in the two-bath spin-boson model. We use the Bloch-Redfield (BR)\nformalism, valid in the very weak system-bath coupling limit, the\nnoninteracting-blip approximation (NIBA), applicable in the non-adiabatic\nlimit, and iterative, numerically-exact path integral tools. These\nmethodologies were originally developed for the description of the dissipative\ndynamics of a quantum system, and here they are applied to explore the problem\nof quantum energy transport in a non-equilibrium setting. Specifically, we\nstudy the weak-to-intermediate system-bath coupling regime at high temperatures\n$k_BT/\\hbar>\\epsilon$, with $\\epsilon$ as the characteristic frequency of the\ntwo-state system. The BR formalism and NIBA can lead to close results for the\ndynamics of the reduced density matrix (RDM) in a certain range of parameters.\nHowever, relatively small deviations in the RDM dynamics propagate into\nsignificant qualitative discrepancies in the transport behavior. Similarly,\nbeyond the strict non-adiabatic limit NIBA's prediction for the heat current is\nqualitatively incorrect: It fails to capture the turnover behavior of the\ncurrent with tunneling energy and temperature. Thus, techniques that proved\nmeaningful for describing the RDM dynamics, to some extent even beyond their\nrigorous range of validity, should be used with great caution in heat transfer\ncalculations, since qualitative-serious failures develop once parameters are\nmildly stretched beyond the techniques' working assumptions."
    },
    {
        "anchor": "Quantum magnetotransport in a bilayer MoS2: influence of a perpendicular\n  electric field: We first derive the energy dispersion of bilayer MoS$_{2}$ in the presence of\na perpendicular electric field $E_z$. We show that the band gap and layer\nsplitting can be controlled by the field $E_z$. Away from the $k$ point, the\nintrinsic SOC splitting increases in the conduction band but is weakly affected\nin the valence band. We then analyze the band structure in the presence of a\nperpendicular magnetic field $B$ and the field $E_z$, including spin and valley\nZeeman terms, and evaluate the Hall and longitudinal conductivities. We discuss\nthe numerical results as functions of the fields $B$ and $E_z$ for finite\ntemperatures. The field $B$ gives rise to a significant spin splitting in the\nconduction band, to a beating in the Shubnikov-de Haas (SdH) oscillations when\nit's weak, and to their splitting when it's strong. The Zeeman terms and\n$E_{z}$ suppress the beating and change the positions of the beating nodes of\nthe SdH oscillations at low $B$ fields and enhance their splitting at high $B$\nfields. Similar beating patterns are observed in the spin and valley\npolarizations at low $B$ fields. Interestingly, a $90\\%$ spin polarization and\na $100\\%$ square-wave-shaped valley polarization are observed at high $B$\nfields. The Hall-plateau sequence depends on $E_z$. These findings may be\npertinent to future spintronic and valleytronic devices.",
        "positive": "Vortex Drag in Quantum Hall Effect: A new model of momentum and electric field transfer between two adjacent 2D\nelectron systems in the Quantum Hall Effect is proposed. The drag effect is due\nto momentum transfer from the vortex system of one layer to the vortex system\nof another layer. The remarkable result of this approach is periodical change\nof $sign$ of the dragged electric field with difference between the layer\nfilling factors."
    },
    {
        "anchor": "AC Josephson current and supercurrent noise through one-dimensional\n  correlated electron systems: AC Josephson effect in one-dimensional Tomonaga-Luttinger liquid (TLL)\nadiabatically connected to superconducting electrodes is theoretically\ninvestigated. It is found that density fluctuations due to repulsive\nelectron-electron interactions in TLL inhibit Josephson oscillations, whereas\nthey do not affect time-independent current part. We also show that the\nfluctuations reduce supercurrent noise caused by multiple Andreev reflections.\nThis indicates that the quantum fluctuations in TLL disturb the superconducting\nphase coherence spreading across the junction.",
        "positive": "Can Dirac fluid in graphene be made more perfect?: To answer this question, we discuss the properties of electronic viscosity in\ndeformed graphene by introducing strain and velocity gradient as\npseudo-magnetic and pseudo-electric fields, respectively, into the Dirac model.\nWe found that viscosity decreases with applied strain, simultaneously leading\nto a rather significant increase of the Reynolds number and enabling a real\npossibility for manifestation of noticeable turbulent effects in strained\ngraphene."
    },
    {
        "anchor": "Majorana excitons in a Kitaev chain of semiconductor quantum dots in a\n  nanowire: We present here a theory of Majorana excitons, photo-excited conduction\nelectron-valence band hole pairs, interacting with Majorana Fermions in a\nKitaev chain of semiconductor quantum dots embedded in a nanowire. Using\nanalytical tools and exact diagonalisation methods we identify the presence of\nMajorana Zero Modes in the nanowire absorption spectra.",
        "positive": "Vanishing of the quantum spin Hall phase in a semi-Dirac Kane Mele model: We study the vanishing of the topological properties of a quantum spin Hall\ninsulator induced by a deformation of the band structure that interpolates\nbetween the Dirac and the semi-Dirac limits of a tight-binding model on a\nhoneycomb lattice. The above scenario is mimicked in a simple model, where\nthere exists a differential hopping along one of the three neighbours (say,\n$t_1$) compared to the other two (say, $t$). For $t_1 = t$, the properties of\nthe quantum spin Hall phase is described by the familiar Kane Mele model, while\n$t<t_1<2t$ denotes a situation in which the spin resolved bands are\ncontinuously deformed. $t_1 = 2t$ represents a special case which is called as\nthe semi-Dirac limit. Here, the spectral gaps between the conduction and the\nvalence bands vanish. A closer inspection of the properties of such a deformed\nsystem yields insights on a topological phase transition occurring at the\nsemi-Dirac limit, which continues to behave as a band insulator for $t_1>2t$.\nWe demonstrate the evolution of the topological phase in presence of the Rashba\nand intrinsic spin-orbit couplings via computing the electronic band structure,\nedge modes in a nanoribbon and the $\\mathbb{Z}_2$ invariant. The latter aids in\narriving at the phase diagram which conclusively shows vanishing of the\ntopological phase in the semi-Dirac limit. Further we demonstrate in gradual\nnarrowing down of the plateau in the spin Hall conductivity, which along with a\nphase diagram provide robust support on the vanishing of the $\\mathbb{Z}_2$\ninvariant and hence the quantum spin Hall phase."
    },
    {
        "anchor": "Imaging fractional incompressible stripes in integer quantum Hall\n  systems: Transport experiments provide conflicting evidence on the possible existence\nof fractional order within integer quantum Hall systems. In fact integer edge\nstates sometimes behave as monolithic objects with no inner structure, while\nother experiments clearly highlight the role of fractional substructures.\nRecently developed low-temperature scanning probe techniques offer today an\nopportunity for a deeper-than-ever investigation of spatial features of such\nedge systems. Here we use scanning gate microscopy and demonstrate that\nfractional features were unambiguously observed in every integer quantum Hall\nconstriction studied. We present also an experimental estimate of the width of\nthe fractional incompressible stripes corresponding to filling factors 1/3,\n2/5, 3/5, and 2/3. Our results compare well with predictions of the\nedge-reconstruction theory.",
        "positive": "Fano resonances and electron spin transport through a two-dimensional\n  spin-orbit-coupled quantum ring: Electron transport through a spin-orbit-coupled quantum ring is investigated\nwithin linear response theory. We show that the finite width of the ring\nresults in the appearance of Fano resonances in the conductance. This turns out\nto be a consequence of the spin-orbit interaction that leads to a breaking of\nthe parity of the states localized in the ring. The resonances appear when the\nsystem is close to maxima of Aharonov-Casher conductance oscillations where\nspin transfer is heavily modified. When the spin-orbit coupling strength is\ndetuned from the Aharonov-Casher maxima the resonances are broadened resulting\nin a dependence of the spin transport on the electron Fermi energy in contrast\nto predictions from one-dimensional models"
    },
    {
        "anchor": "Electron-phonon interaction in nanodevices: The effect of the up-conversion of the electronic energy level occupation was\nearlier interpreted as an implication of the multiple scattering of the charge\ncarriers on the longitudinal optical phonons of the lattice vibrations in a\nsmall system like a quantum dot. In this work we study the influence of this\neffect on the electronic motion in a nanotransistor represented by a quantum\ndot connected to two electric wires and a gate electrode. We show that in an\nasymmetric nanotransistor the up-conversion effect gives rise to a spontaneous\ncurrent between the source and the drain, or to an appearance of a spontaneous\nvoltage between these electrodes. The effect will be studied basing on the well\nknown Datta's Toy Model of the theoretical description of the nanotransistor\nand on additional kinetic equations giving the multiple scattering of electrons\nin the quantum dot, in the self-consistent Born approximation to the electronic\nself-energy. We shall also briefly discuss the relation of this theoretical\nresult to existing experiments on current-voltage characteristics in gated\nnanostructures.",
        "positive": "Nonlinear ac stationary response and dynamic magnetic hysteresis of\n  quantum uniaxial superparamagnets: The nonlinear ac stationary response of uniaxial paramagnets and\nsuperparamagnets - nanoscale solids or clasters with spin number S ~ 10^0 -\n10^4 - in superimposed uniform ac and dc bias magnetic fields of arbitrary\nstrength, each applied along the easy axis of magnetization, is determined by\nsolving the evolution equation for the reduced density matrix represented as a\nfinite set of three-term differential-recurrence relations for its diagonal\nmatrix elements. The various harmonic components of the magnetization, dynamic\nmagnetic hysteresis loops, etc. are then evaluated via matrix continued\nfractions indicating a pronounced dependence of the nonlinear response on S\narising from the quantum spin dynamics. In the linear response approximation,\nthe results concur with existing solutions."
    },
    {
        "anchor": "Review: Solid-state physics of halide perovskites: Halide perovskite solar cells presented a unique opportunity to apply modern\ncomputational materials science techniques to an (initially) poorly understood\nnew material. In this review, we recount the key understanding developed during\nthe last five years, through a narrative review of research progress. The\ncentral enigma of the material is how it can be so defective, and yet work so\nwell as a photovoltaic. The physical properties of the material were understood\nthrough molecular and lattice dynamic calculations, revealing the material to\nshow large dynamic responses on a wide range of time scales. Longer length\nscales in the material was simulated with effective classical potentials,\nshowing that complex domains can be generated by the interacting molecular\ndipoles, generating structured features in the electrostatic potential of the\nlattice. Relativistic electronic structure reveals unique features in the\nbands, which may explain observed slow recombination, and could be used in high\nefficiency photovoltaics. The large dielectric response of the lattice leads to\na strong drive for the formation of polarons, some device physics of which are\ndiscussed. These polarons offer a possible explanation for the observed slow\ncooling of photoexcitations in the material.",
        "positive": "Tunable Quantum Phase Transitions in a Resonant Level Coupled to Two\n  Dissipative Baths: We study tunneling through a resonant level connected to two dissipative\nbosonic baths: one is the resistive environment of the source and drain leads,\nwhile the second comes from coupling to potential fluctuations on a resistive\ngate. We show that several quantum phase transitions (QPT) occur in such a\nmodel, transitions which emulate those found in interacting systems such as\nLuttinger liquids or Kondo systems. We first use bosonization to map this\ndissipative resonant level model to a resonant level in a Luttinger liquid, one\nwith, curiously, two interaction parameters. Drawing on methods for analyzing\nLuttinger liquids at both weak and strong coupling, we obtain the phase\ndiagram. For strong dissipation, a Berezinsky-Kosterlitz-Thouless QPT separates\nstrong-coupling and weak-coupling (charge localized) phases. In the\nsource-drain symmetric case, all relevant backscattering processes disappear at\nstrong coupling, leading to perfect transmission at zero temperature. In fact,\na QPT occurs as a function of the coupling asymmetry or energy of the resonant\nlevel: the two phases are (i) the system is cut into two disconnected pieces\n(zero transmission), or (ii) the system is a single connected piece with\nperfect transmission, except for a disconnected fractional degree of freedom.\nThe latter arises from the competition between the two fermionic leads (source\nand drain), as in the two-channel Kondo effect."
    },
    {
        "anchor": "Probing the Magnetodynamics of Magnetic Tunnel Junctions with the Aid of\n  SiGe HBTs: High impedance (about 1 Megaohm) magnetic tunnel junctions (MTJs) are used to\nobserve and record the magnetodynamics of the nanomagnets that form the\njunctions themselves. To counteract the bandwidth limitations caused by the\nhigh impedance of the junction and the parasitic capacitance intrinsic to any\ncryogenic system, silicon-germanium heterojunction bipolar transistors (SiGe\nHBTs) are used as cryogenic preamplifiers for the MTJs. The resulting\nmeasurement improvements include an increase in bandwidth by a factor of 3.89,\nan increase in signal-to-noise ratio by a factor of 6.62, and a gain of 7.75 of\nthe TMR signal produced by the MTJ. The limitation to the measurement system\nwas found to be from the external, room temperature electronics. Despite this\nlimitation, these improvements allow for better time-resolved magnetodynamics\nmeasurements of the MTJs. These experiments pave the way for future cryogenic,\nmagnetodynamics measurement improvements, and could even be useful in cryogenic\nmemory applications.",
        "positive": "Force-detected Magnetic Resonance Imaging of Influenza Viruses in the\n  Overcoupled Sensor Regime: Long and thin scanning force cantilevers are sensitive to small forces, but\nalso vulnerable to detrimental non-contact interactions. Here we present an\nexperiment with a cantilever whose spring constant and static deflection are\ndominated by the interaction between the tip and the surface, a regime that we\nrefer to as ``overcoupled''. The interactions are an obstacle for\nultrasensitive measurements like nanoscale magnetic resonance imaging\n(nanoMRI). We discuss several strategies to overcome the challenges presented\nby the overcoupling, and demonstrate proton nanoMRI measurements of individual\ninfluenza virus particles."
    },
    {
        "anchor": "Parafermion statistics and the application to non-abelian quantum Hall\n  states: The (exclusion) statistics of parafermions is used to study degeneracies of\nquasiholes over the paired (or in general clustered) quantum Hall states. Focus\nis on the Z_k and su(3)_k/u(1)^2 parafermions, which are used in the\ndescription of spin-polarized and spin-singled clustered quantum Hall states.",
        "positive": "Electron-electron interaction in 2D and 1D ferromagnetic (Ga,Mn)As: We investigated the magnetotransport in high quality ferromagnetic (Ga,Mn)As\nfilms and wires. At low temperature the conductivity decreases with decreasing\ntemperature without saturation down to 20 mK. Here we show, that the\nconductivity decrease follows a ln($T/T_0$) dependency in 2D films and a\n$-1/\\sqrt{T}$ dependency in 1D wires and is independent of an applied magnetic\nfield. This behavior can be explained by the theory of electron-electron\ninteraction."
    },
    {
        "anchor": "Spin, atomic and inter-atomic orbital magnetism induced by 3d\n  nanostructures deposited on transition metal surfaces: We present a first-principles study of the surface magnetism induced by Cr,\nMn, Fe and Co adatoms on the (111) surfaces of Rh, Pd, Ag, Ir, Pt and Au. We\nfirst describe how the different contributions to the surface magnetism enter\nthe magnetic stray field, with special attention paid to the induced orbital\nmoments. Then we present results for the spin and orbital magnetic moments of\nthe adatoms, and for the induced surface spin and orbital magnetic moments, the\nlatter being further divided into atomic and inter-atomic contributions. We\ninvestigate how the surface magnetism is determined by the chemical nature of\nthe elements involved, such as the filling of the magnetic d-orbitals of the\nadatoms and the properties of the itinerant electrons at the surface (whether\nthey are sp- or d-like, and whether the spin-orbit interaction is relevant),\nand how it is modified if the magnetic adatoms are brought together to form a\ncluster, with Cr, Mn, Fe, and Co trimers on Pt(111) as an example. We also\nexplore the impact of computational approximations, such as the distance\nbetween the adatom and the Pt(111) surface, or confinement effects due to the\nfinite thickness of the slab used to model it. Our discussion of the magnetic\nstray field generated by a single adatom and its environment suggests a\npossible way of disentangling the induced surface magnetism from the adatom\none, which could be feasible with scanning NV-center microscopy.",
        "positive": "Spin Degeneracy and Conductance Fluctuations in Open Quantum Dots: The dependence of mesoscopic conductance fluctuations on parallel magnetic\nfield is used as a probe of spin degeneracy in open GaAs quantum dots. The\nvariance of fluctuations at high parallel field is reduced from the low-field\nvariance (with broken time-reversal symmetry) by factors ranging from roughly\ntwo in a 1 square-micron dot at low temperature, to four or greater in 8\nsquare-micron dots. The factor of two is expected for simple Zeeman splitting\nof spin degenerate channels. A possible explanation for the unexpected larger\nfactors in terms of field-dependent spin orbit scattering is proposed."
    },
    {
        "anchor": "Topological Aspects of Antiferromagnets: The long fascination antiferromagnetic materials have exerted on the\nscientific community over about a century has been entirely renewed recently\nwith the discovery of several unexpected phenomena including various classes of\nanomalous spin and charge Hall effects and unconventional magnonic transport,\nbut also homochiral magnetic entities such as skyrmions. With these\nbreakthroughs, antiferromagnets standout as a rich playground for the\ninvestigation of novel topological behaviors, and as promising candidate\nmaterials for disruptive low-power microelectronic applications. Remarkably,\nthe newly discovered phenomena are all related to the topology of the magnetic,\nelectronic or magnonic ground state of the antiferromagnets. This review\nexposes how non-trivial topology emerges at different levels in\nantiferromagnets and explores the novel mechanisms that have been discovered\nrecently. We also discuss how novel classes of quantum magnets could enrich the\ncurrently expanding field of antiferromagnetic spintronics and how spin\ntransport can in turn favor a better understanding of exotic quantum\nexcitations.",
        "positive": "Hybrid-order topological insulators in a phononic crystal: Topological phases, including the conventional first-order and higher-order\ntopological insulators and semimetals, have emerged as a thriving topic in the\nfields of condensed-matter physics and material science. Usually, a topological\ninsulator is characterized by a fixed order topological invariant and exhibits\nassociated bulk-boundary correspondence. Here, we realize a new type of\ntopological insulator in a bilayer phononic crystal, which hosts simultaneously\nthe first-order and second-order topologies, referred here as the hybrid-order\ntopological insulator. The one-dimensional gapless helical edge states, and\nzero-dimensional corner states coexist in the same system. The new hybrid-order\ntopological phase may produce novel applications in topological acoustic\ndevices."
    },
    {
        "anchor": "Robustness of topologically protected surface states in layering of\n  Bi2Te3 thin films: Bulk Bi2Te3 is known to be a topological insulator. We investigate surface\nstates of Bi2Te3(111) thin films using density-functional theory including\nspin-orbit coupling. We construct a method to unambiguously identify surface\nstates of thin film topological insulators. Applying this method for one to six\nquintuple layers of Bi2Te3, we find that the topological nature of the surface\nstates remains robust with the film thickness and that the films of three or\nmore quintuple layers have topologically non-trivial or protected surface\nstates, in agreement with recent experiments.",
        "positive": "Multiband effects and the possible Dirac states in LaAgSb$_2$: Here we report the possible signature of Dirac fermions in the\nmagnetoresistance, Hall resistivity and magnetothermopower of LaAgSb$_2$. The\nopposite sign between Hall resistivity and Seebeck coefficient indicates the\nmultiband effect. Electronic structure calculation reveals the existence of the\nlinear bands and the parabolic bands crossing the Fermi level. The large linear\nmagnetoresistance was attributed to the quantum limit of the possible Dirac\nfermions or the breakdown of weak-field magnetotransport at the charge density\nwave phase transition. Analysis of Hall resistivity using two-band model\nreveals that Dirac holes which dominate the electronic transport have much\nhigher mobility and larger density than conventional electrons. Magnetic field\nsuppresses the apparent Hall carrier density, and also induces the sign change\nof the Seebeck coefficient from negative to positive. These effects are\npossibly attributed to the magnetic field suppression of the density of states\nat the Fermi level originating from the quantum limit of the possible Dirac\nholes."
    },
    {
        "anchor": "Resonant laser excitation and time-domain imaging of chiral topological\n  polariton edge states: We investigate the dynamics of chiral edge states in topological polariton\nsystems under laser driving. Using a model system comprised of topolgically\ntrivial excitons and photons with a chiral coupling proposed by Karzig et al.\n[Phys. Rev. X 5, 031001 (2015)], we investigate the real-time dynamics of a\nlattice version of this model driven by a laser pulse. By analyzing the time-\nand momentum-resolved spectral function, measured by time- and angle-resolved\nphotoluminescence in analogy with time- and angle-resolved photoemission\nspectroscopy in electronic systems, we find that polaritonic states in a ribbon\ngeometry are selectively excited via their resonance with the pump laser photon\nfrequency. This selective excitation mechanism is independent of the necessity\nof strong laser pumping and polariton condensation. Our work highlights the\npotential of time-resolved spectroscopy as a complementary tool to real-space\nimaging for the investigation of topological edge state engineering in devices.",
        "positive": "Optics of spin-noise-induced gyrotropy of asymmetric microcavity: The optical gyrotropy noise of a high-finesse semiconductor Bragg microcavity\nwith an embedded quantum well (QW) is studied at different detunings of the\nphoton mode and the QW exciton resonances. A strong suppression of the noise\nmagnitude for the photon mode frequencies lying above exciton resonances is\nfound. We show that such a critical behavior of the observed optical noise\npower is specific of asymmetric Fabry-Perot resonators. As follows from our\nanalysis, at a certain level of intracavity loss, the reflectivity of the\nasymmetric resonator vanishes, while the polarimetric sensitivity to the\ngyrotropy changes dramatically when moving across the critical point. The\nresults of model calculations are in a good agreement with our experimental\ndata on the spin noise in a single-quantum-well microcavity and are confirmed\nalso by the spectra of the photo-induced Kerr rotation in the pump-probe\nexperiments."
    },
    {
        "anchor": "Stable oscillation in spin torque oscillator excited by a small in-plane\n  magnetic field: Theoretical conditions to excite self-oscillation in a spin torque oscillator\nconsisting of a perpendicularly magnetized free layer and an in-plane\nmagnetized pinned layer are investigated by analytically solving the\nLandau-Lifshitz-Gilbert equation. The analytical relation between the current\nand oscillation frequency is derived. It is found that a large amplitude\noscillation can be excited by applying a small field pointing to the direction\nanti-parallel to the magnetization of the pinned layer. The validity of the\nanalytical results is confirmed by comparing with numerical simulation, showing\ngood agreement especially in a low current region.",
        "positive": "Electric field induced gap modification in ultrathin blue phosphorous: We investigate the possibility of band structure engineering in the recently\npredicted 2D layered form of blue phosphorus via an electric field (E$_z$)\napplied perpendicular to the layer(s). Using density functional theory, we\nstudy the effect of a transverse electric field in monolayer, as well as three\ndifferently stacked bilayer structures of blue phosphorus. We find that, for\nE$_z > 0.2$ V/\\AA the direct energy gap at the $\\Gamma$ point, which is much\nlarger than the default indirect band gap of mono- and bilayer blue phosphorus,\ndecreases linearly with the increasing electric field; becomes comparable to\nthe default indirect band gap at E$_z \\approx 0.45 (0.35)$ V/\\AA for monolayer\n(bilayers) and decreases further until the semiconductor to metal transition of\n2D blue phosphorus takes place at E$_z\\approx 0.7 (0.5)$ V/\\AA for monolayer\n(bilayers). Calculated values of the electron and hole effective masses along\nvarious high symmetry directions in the reciprocal lattice suggests that the\nmobility of charge carriers is also influenced by the applied electric field."
    },
    {
        "anchor": "Stochastic syncing in sinusoidally driven atomic orbital memory: Stochastically fluctuating multi-well systems as physical implementations of\nenergy-based machine learning models promise a route towards neuromorphic\nhardware. Understanding the response of multi-well systems to dynamic input\nsignals is crucial in this regard. Here, we investigate the stochastic response\nof binary orbital memory states derived from individual Fe and Co atoms on a\nblack phosphorus surface to sinusoidal input voltages. Using scanning tunneling\nmicroscopy, we quantify the state residence times for DC and AC voltage drive\nwith various input frequencies. We find that Fe and Co atoms both exhibit\nfeatures of synchronization to the AC input, but only Fe atoms demonstrate a\nsignificant frequency-dependent change in the time-averaged state occupations.\nBy modeling the underlying stochastic process, we show that the frequency\nresponse of the system is directly related to the DC voltage dependence of the\nstate asymmetry. This relation provides a tunable way to induce population\nchanges in stochastic systems and lays the foundation for understanding the\nresponse of multi-well systems to dynamical input signals.",
        "positive": "Interface engineering of charge-transfer excitons in 2D lateral\n  heterostructures: The existence of bound charge transfer (CT) excitons at the interface of\nmonolayer lateral heterojunctions has been debated in literature, but contrary\nto the case of interlayer excitons in vertical heterostructure their\nobservation still has to be confirmed. Here, we present a microscopic study\ninvestigating signatures of bound CT excitons in photoluminescence spectra at\nthe interface of hBN-encapsulated lateral MoSe$_2$-WSe$_2$ heterostructures.\nBased on a fully microscopic and material-specific theory, we reveal the\nmany-particle processes behind the formation of CT excitons and how they can be\ntuned via interface- and dielectric engineering. For junction widths smaller\nthan the Coulomb-induced Bohr radius we predict the appearance of a low-energy\nCT exciton. The theoretical prediction is compared with experimental\nlow-temperature photoluminescence measurements showing emission in the bound CT\nexcitons energy range. Our joint theory-experiment study presents a significant\nstep towards a microscopic understanding of optical properties of\ntechnologically promising 2D lateral heterostructures."
    },
    {
        "anchor": "Background charges and quantum effects in quantum dots transport\n  spectroscopy: We extend a simple model of a charge trap coupled to a single-electron box to\nenergy ranges and parameters such that it gives new insights and predictions\nreadily observable in many experimental systems. We show that a single\nbackground charge is enough to give lines of differential conductance in the\nstability diagram of the quantum dot, even within undistorted Coulomb diamonds.\nIt also suppresses the current near degeneracy of the impurity charge, and\nyields negative differential lines far from this degeneracy. We compare this\npicture to two other accepted explanations for lines in diamonds, based\nrespectively on the excitation spectrum of a quantum dot and on fluctuations of\nthe density-of-states in the contacts. In order to discriminate between these\nmodels we emphasize the specific features related to environmental charge\ntraps. Finally we show that our model accounts very well for all the anomalous\nfeatures observed in silicon nanowire quantum dots.",
        "positive": "Strong surface scattering in ultrahigh mobility Bi2Se3 topological\n  insulator crystals: While evidence of a topologically nontrivial surface state has been\nidentified in surface-sensitive measurements of Bi2Se3, a significant\nexperimental concern is that no signatures have been observed in bulk\ntransport. In a search for such states, nominally undoped single crystals of\nBi2Se3 with carrier densities approaching 10^16 cm^-3 and very high mobilities\nexceeding 2 m^2 V^-1 s^-1 have been studied. A comprehensive analysis of\nShubnikov de Haas oscillations, Hall effect, and optical reflectivity indicates\nthat the measured electrical transport can be attributed solely to bulk states,\neven at 50 mK at low Landau level filling factor, and in the quantum limit. The\nabsence of a significant surface contribution to bulk conduction demonstrates\nthat even in very clean samples, the surface mobility is lower than that of the\nbulk, despite its topological protection."
    },
    {
        "anchor": "Nonlocal thermoelectric resistance in vortical viscous transport: The pursuit for clearly identifiable signatures of viscous electron flow in\nthe solid state systems has been a paramount task in the search of the\nhydrodynamic electron transport behavior. In this work, we investigate\ntheoretically the nonlocal electric and thermal resistances for the generic\nnon-Galilean-invariant electron liquids in the multiterminal Hall-bar devices\nin the hydrodynamic regime. The role of the device inhomogeneity is carefully\naddressed in the model of the disorder potential with the long-range\ncorrelation radius. We obtain analytic expressions for the thermoelectric\nresistances that are applicable in the full crossover regime from charge\nneutrality to high electron density. We show that the vortical component of the\nelectron flow manifests in the thermal transport mode close to the charge\nneutrality where vorticity is already suppressed by the intrinsic conductivity\nin the electric current. This behavior can be tested by the high-resolution\nthermal imaging probes.",
        "positive": "Scattering formula for the topological quantum number of a disordered\n  multi-mode wire: The topological quantum number Q of a superconducting or chiral insulating\nwire counts the number of stable bound states at the end points. We determine Q\nfrom the matrix r of reflection amplitudes from one of the ends, generalizing\nthe known result in the absence of time-reversal and chiral symmetry to all\nfive topologically nontrivial symmetry classes. The formula takes the form of\nthe determinant, Pfaffian, or matrix signature of r, depending on whether r is\na real matrix, a real antisymmetric matrix, or a Hermitian matrix. We apply\nthis formula to calculate the topological quantum number of N coupled dimerized\npolymer chains, including the effects of disorder in the hopping constants. The\nscattering theory relates a topological phase transition to a conductance peak,\nof quantized height and with a universal (symmetry class independent) line\nshape. Two peaks which merge are annihilated in the superconducting symmetry\nclasses, while they reinforce each other in the chiral symmetry classes."
    },
    {
        "anchor": "Uniaxial stress controlled anisotropic Rashba effects and carriers-based\n  currents in BiTeI monolayer semiconductor: Manipulation of Rashba effects in two-dimensional (2D) electron systems is\nhighly desirable for controllable applications in spintronics and\noptoelectronics. Here, by combining first-principles investigation and model\nanalysis, we use uniaxial stress to control BiTeI monolayer as a Rashba 2D\nsemiconductor for useful spin and transport properties. We find that the\nstress-driven electron system can be described by an effective anisotropic\nRashba model including all the three Pauli matrixes, and uniaxial stress allows\nan out-of-plane spin component. When appropriate electron carriers are\nintroduced into the monolayer, an in-plane electric field can induce a charge\ncurrent and three spin current components (including that based on the\nout-of-plane spin) because of the reduced symmetry. Therefore, uniaxial stress\ncan be used to control such Rashba 2D electron systems as the BiTeI monolayer\nfor seeking promising devices.",
        "positive": "Efficient spin-current injection in single-molecule magnet junctions: We study theoretically spin transport through a single-molecule magnet (SMM)\nin the sequential and cotunneling regimes, where the SMM is weakly coupled to\none ferromagnetic and one normalmetallic leads. By a master-equation approach,\nit is found that the spin polarization injected from the ferromagnetic lead is\namplified and highly polarized spin-current can be generated, due to the\nexchange coupling between the transport electron and the anisotropic spin of\nthe SMM. Moreover, the spin-current polarization can be tuned by the gate or\nbias voltage, and thus an efficient spin injection device based on the SMM is\nproposed in molecular spintronics."
    },
    {
        "anchor": "Non-local spectroscopy of Andreev bound states: We experimentally investigate Andreev bound states (ABSs) in a carbon\nnanotube quantum dot (QD) connected to a superconducting Nb lead (S). A weakly\ncoupled normal metal contact acts as a tunnel probe that measures the energy\ndispersion of the ABSs. Moreover we study the response of the ABS to non-local\ntransport processes, namely Cooper pair splitting and elastic co-tunnelling,\nthat are enabled by a second QD fabricated on the same nanotube on the opposite\nside of S. We find an appreciable non-local conductance with a rich structure,\nincluding a sign reversal at the ground state transition from the ABS singlet\nto a degenerate magnetic doublet. We describe our device by a simple rate\nequation model that captures the key features of our observations and\ndemonstrates that the sign of the non-local conductance is a measure for the\ncharge distribution of the ABS, given by the respective Bogoliubov-de Gennes\namplitudes $u$ and $v$.",
        "positive": "Impulsive Fermi magnon-phonon resonance in antiferromagnetic $CoF_{2}$: Understanding spin-lattice interactions in antiferromagnets is one of the\nmost fundamental issues at the core of the recently emerging and booming fields\nof antiferromagnetic spintronics and magnonics. Recently, coherent nonlinear\nspin-lattice coupling was discovered in an antiferromagnet which opened the\npossibility to control the nonlinear coupling strength and thus showing a novel\npathway to coherently control magnon-phonon dynamics. Here, utilizing intense\nnarrow band terahertz (THz) pulses and tunable magnetic fields up to 7 T, we\nexperimentally realize the conditions of the Fermi magnon-phonon resonance in\nantiferromagnetic $CoF_{2}$. These conditions imply that both the spin and the\nlattice anharmonicities harvest energy transfer between the subsystems, if the\nmagnon eigenfrequency $f_{m}$ is twice lower than the frequency of the phonon\n$2f_{m}=f_{ph}$. Performing THz pump-infrared probe spectroscopy in conjunction\nwith simulations, we explore the coupled magnon-phonon dynamics in the vicinity\nof the Fermi-resonance and reveal the corresponding fingerprints of an\nimpulsive THz-induced response. This study focuses on the role of nonlinearity\nin spin-lattice interactions, providing insights into the control of coherent\nmagnon-phonon energy exchange."
    },
    {
        "anchor": "Nonadiabatic Electron Pumping: Maximal Current with Minimal Noise: The noise properties of pump currents through an open double quantum dot\nsetup with non-adiabatic ac driving are investigated. Driving frequencies close\nto the internal resonances of the double dot-system mark the optimal working\npoints at which the pump current assumes a maximum while its noise power\npossesses a remarkably low minimum. A rotating-wave approximation provides\nanalytical expressions for the current and its noise power and allows to\noptimize the noise characteristics. The analytical results are compared to\nnumerical results from a Floquet transport theory.",
        "positive": "Strongly Coupled Spins of Silicon-Vacancy Centers Inside a Nanodiamond\n  with Sub-Megahertz Linewidth: The search for long-lived quantum memories, which can be efficiently\ninterfaced with flying qubits is longstanding. One possible solution is to use\nthe electron spin of a color center in diamond to mediate interaction between a\nlong-lived nuclear spin and a photon. Realizing this in a nanodiamond\nfurthermore facilitates the integration into photonic devices and enables the\nrealization of hybrid quantum systems with access to quantum memories. Here, we\ninvestigated the spin environment of negatively-charged Silicon-Vacancy centers\nin a nanodiamond and demonstrate strong coupling of its electron spin, while\nthe electron spin's decoherence rate remained below 1 MHz. We furthermore\ndemonstrate multi-spin coupling with the potential to establish registers of\nquantum memories in nanodiamonds."
    },
    {
        "anchor": "Nonequilibrium Dynamics of Gating-Induced Resistance Transition in\n  Charge Density Wave Insulators: We present a comprehensive numerical study of the gating-induced\ninsulator-to-metal transition in the charge density wave (CDW) state of the\nHolstein model. Large-scale Brownian dynamics method with forces computed from\nnonequilibrium Green's function method is employed to simulate the\nspatio-temporal dynamics of the CDW state. We show that a threshold voltage,\ndetermined by the energy of the in-gap edge modes, is required to induce the\ninstability of the CDW. A large bias voltage, on the other hand, induces a\nsudden transition to the metallic state similar to a dielectric breakdown. At\nintermediate voltages, our extensive simulations show that the transition to\nthe low-resistance state is initiated by the nucleation of a thin conducting\nlayer at the gating electrode. The resultant metal-insulator interface is then\nswept over the system by the voltage bias, resulting in a growing metallic\ndomain. We further characterize the voltage and temperature dependence of the\ndomain-wall dynamics.",
        "positive": "Time scales for Majorana manipulation using Coulomb blockade in\n  gate-controlled superconducting nanowires: We numerically compute the low-energy spectrum of a gate-controlled\nsuperconducting topological nanowire segmented into two islands, each\nJosephson-coupled to a bulk superconductor. This device may host two pairs of\nMajorana bound states and could provide a platform for testing Majorana fusion\nrules. We analyze the crossover between (i) a charge-dominated regime\nutilizable for initialization and readout of Majorana bound states, (ii) a\nsingle-island regime for dominating inter-island Majorana coupling, (iii) a\nJosephson-plasmon regime for large coupling to the bulk superconductors, and\n(iv) a regime of four Majorana bound states allowing for topologically\nprotected Majorana manipulations. From the energy spectrum, we derive\nconservative estimates for the time scales of a fusion-rule testing protocol\nproposed recently [arXiv:1511.05153]. We also analyze the steps needed for\nbasic Majorana braiding operations in branched nanowire structures."
    },
    {
        "anchor": "Indirect exchange interaction between magnetic impurities near the\n  helical edge: The indirect exchange interaction between magnetic impurities located in the\nbulk of a two-dimensional topological insulator decays exponentially with the\ndistance. The indirect exchange interaction for magnetic impurities mediated by\nthe helical states at the edge of the topological insulator demonstrates\nbehaviour which is typical for the Ruderman-Kittel-Kasuya-Yosida interaction in\na one-dimensional metal. We have shown that interference between the bulk and\nedge states in the two-dimensional topological insulator results in existence\nof the unusual contribution to the indirect exchange interaction which, on the\none hand, decays exponentially with a distance at the length scale controlled\nby the Fermi energy of the edge states and, on the other hand, oscillates with\ndistance along the helical edge with the period determined by the Fermi wave\nlength. We found that this interference contribution to the indirect exchange\ninteraction becomes dominant for such configurations of two magnetic impurities\nwhen one of them is situated close to the helical edge whereas the other one is\nlocated far away in the bulk.",
        "positive": "Negative to Positive Crossover of Magnetoresistance in Layered WS2 with\n  Ohmic Contact: The discovery of graphene has ignited intensive investigation on two\ndimensional (2D) materials. Among them, transition metal dichalcogenide (TMDC),\na typical representative, attracts much attention due to the excellent\nperformance in field effect transistor (FET) related measurements and\napplications. Particularly, when TMDC eventually reaches few-layer dimension, a\nwide range of electronic and optical properties, in striking contrast to bulk\nsamples, are detected. In this Letter, we synthesized single crystalline WS2\nnanoflakes by physical vapor deposition (PVD) method and carried out a series\nof transport measurements of contact resistance and magnetoresistance. Focused\nion beam (FIB) technology was applied to deposit Pt electrodes on WS2 flakes.\nDifferent from the electron beam lithography (EBL) fabricated electrodes,\nFIB-deposited leads exhibited ohmic contact, resolving the dilemma of Schottky\nbarrier. Furthermore, a temperature-modulated negative-to-positive transition\nof magnetoresistance (MR) associated with a crossover of carrier type at\nsimilar temperature was demonstrated. Our work offers a pathway to optimize the\ncontact for TMDC and reveals the magnetoresistance characteristics of WS2\nflakes, which may stimulate further studies on TMDC and corresponding potential\nelectronic and optoelectronic applications."
    },
    {
        "anchor": "Microwave response of an Andreev bound state: We develop a theory for the dynamics of an Andreev bound state hosted by a\nweak link of finite length for which charging effects are important. We derive\nthe linear response of both the current through the link and charge accumulated\nin it with respect to the phase and gate voltage biases. The resulting matrix\nencapsulates the spectroscopic properties of a weak link embedded in a\nmicrowave resonator. In the low-frequency limit, we obtain the response\nfunctions analytically using an effective low-energy Hamiltonian, which we\nderive. This Hamiltonian minimally accounts for Coulomb interaction and is\nsuitable for a phenomenological description of a weak link having a finite\nlength.",
        "positive": "Room temperature deep UV photoluminescence from low dimensional\n  hexagonal boron nitride prepared using a facile synthesis: Evaluation of the defect levels in low-dimensional materials is an important\naspect of quantum science. In this article, we report a facile synthesis method\nof hexagonal boron nitride (h-BN) and evaluate the defects and their light\nemission characteristics. The thermal annealing procedure is optimized to\nobtain clean h-BN. The UV-Vis spectroscopy shows the optical energy gap of 5.28\neV which is comparable to the reported energy gap for exfoliated, clean h-BN\nsamples. The optimized synthesis route of h-BN has generated two kinds of\ndefects which are characterised using room temperature photoluminescence\nmeasurements. The defects emit light at 4.18 eV (in deep ultraviolet region)\nand 3.44 eV (ultraviolet), respectively. The defect emitting deep ultraviolet\n(DUV) has oscillatory dependency on the excitation energy, while that emitting\n3.44 eV light (ZPL3.44 eV) has a phonon bands with mean energy level separation\nof 125 meV measured at room temperature. This agrees very well with the\nFranck-Condon-like structure having regularly spaced energy levels, which are\ntypical indications of single defect levels in the low dimensional h-BN."
    },
    {
        "anchor": "A brief review of thermal transport in mesoscopic systems from\n  nonequilibrium Green's function approach: With the rapidly increasing integration density and power density in\nnanoscale electronic devices, the thermal management concerning heat generation\nand energy harvesting becomes quite crucial. Since phonon is the major heat\ncarrier in semiconductors, thermal transport due to phonons in mesoscopic\nsystems has attracted much attention. In quantum transport studies, the\nnonequilibrium Green's function (NEGF) method is a versatile and powerful tool\nthat has been developed for several decades. In this review, we will discuss\ntheoretical investigations of thermal transport using the NEGF approach from\ntwo aspects. For the aspect of phonon transport, the phonon NEGF method is\nbriefly introduced and its applications on thermal transport in mesoscopic\nsystems including one-dimensional atomic chains, multi-terminal systems, and\ntransient phonon transport are discussed. For the aspect of thermoelectric\ntransport, the caloritronic effects in which the charge, spin, and valley\ndegrees of freedom are manipulated by the temperature gradient are discussed.\nThe time-dependent thermoelectric behavior is also presented in the transient\nregime within the partitioned scheme based on the NEGF method.",
        "positive": "Rippled state of double-layer quantum Hall systems: The incommensurate phase of a bilayer quantum Hall state is found to have a\n``rippled'' dipole charge density whenever the layers are unbalanced. This\ntunable dipole-density-wave instability could be detected by sensitive\ncapacitance measurements and by anisotropic transport. We demonstrate this\nexplicitly by carrying out a Hartree-Fock calculation of the layer densities\nand capacitance for a double-layer quantum Hall state at a total filling factor\nof 1."
    },
    {
        "anchor": "Effect of clustering on ellipsometric spectra of randomly distributed\n  gold nanoparticles on a substrate: We present a theoretical model for describing light scattering from randomly\ndistributed Au nanoparticles on a substrate, including the clustering effect.\nBy using the finite-element Green function method and spherical harmonic basis\nfunctions, we are able to calculate the polarization-dependent reflectivity\nspectra of the system (modeled by randomly distributed nanoparticles coupled\nwith clusters) efficiently and accurately. The calculated ellipsometric spectra\nof the system with clusters can adequately describe the experimental data for\nthe whole frequency range. We find that the clustering effect leads to some\nprominent features in the low frequency range of the ellipsometric spectra,\nwhich are attributed to plasmonic resonances associated with the coupling of Au\nnanoparticles and clusters.",
        "positive": "Violation of the fluctuation-dissipation theorem in time-dependent\n  mesoscopic heat transport: We have analyzed the spectral density of fluctuations of the energy flux\nthrough a mesoscopic constriction between two equilibrium reservoirs. It is\nshown that at finite frequencies, the fluctuating energy flux is not related to\nthe thermal conductance of the constriction by the standard\nfluctuation-dissipation theorem, but contains additional noise. The main\nphysical consequence of this extra noise is that the fluctuations do not vanish\nat zero temperature together with the vanishing thermal conductance."
    },
    {
        "anchor": "Effects of bond disorder and surface amorphization on optical phonon\n  lifetimes and Raman peak shape in crystalline nanoparticles: Optical phonons in nanoparticles with the randomness of interatomic bonds are\nconsidered both analytically and numerically. For weak dilute disorder two\nqualitatively different regimes of separated and overlapped levels are\nobserved, resembling the case of random atomic masses investigated previously.\nAt stronger and/or more dense disorder, the particles become essentially\ninhomogeneous, thus constituting the minimal model to describe an amorphous\nphase, where the picture of vibrational modes becomes more subtle. We\nconcentrate here on the experimentally relevant case of strong disorder located\nnear the particle surface and formulate the core-shell model aimed to describe\nthe ubiquitous phenomenon of particle surface amorphization. We observe a\npeculiar effect of volume optical phonons \"repelling\" from the disordered\nshell. It results in the Raman spectrum in the form of a combination of narrow\nwell-resolved peaks stemming from the quantized modes of a pure particle core\n(red-shifted due to its effective smaller size), and the noisy background\nsignal from the disordered shell placed primarily to the right from the main\nRaman peak.",
        "positive": "A proposal to probe quantum non-locality of Majorana fermions in\n  tunneling experiments: Topological Majorana fermion (MF) quasiparticles have been recently suggested\nto exist in semiconductor quantum wires with proximity induced\nsuperconductivity and a Zeeman field. Although the experimentally observed zero\nbias tunneling peak and a fractional ac-Josephson effect can be taken as\nnecessary signatures of MFs, neither of them constitutes a sufficient \"smoking\ngun\" experiment. Since one pair of Majorana fermions share a single\nconventional fermionic degree of freedom, MFs are in a sense fractionalized\nexcitations. Based on this fractionalization we propose a tunneling experiment\nthat furnishes a nearly unique signature of end state MFs in semiconductor\nquantum wires. In particular, we show that a \"teleportation\"-like experiment is\nnot enough to distinguish MFs from pairs of MFs, which are equivalent to\nconventional zero energy states, but our proposed tunneling experiment, in\nprinciple, can make this distinction."
    },
    {
        "anchor": "Quantum confined Rydberg excitons in Cu$_2$O nanoparticles: The quantum confinement of Rydberg excitons is an important step towards\nexploiting their large nonlinearities for quantum applications. We observe\nRydberg excitons in natural nanoparticles of Cu$_2$O. We resolve up to the\nprincipal quantum number $n=12$ in a bulk Cu$_2$O crystal and up to $n=6$ in\nnanoparticles extracted from the same crystal. The exciton transitions in\nnanoparticles are broadened and their oscillator strengths decrease as $\\propto\nn^{-4}$ compared to those in the bulk (decreasing as $\\propto n^{-3}$). We\nexplain our results by including the effect of quantum confinement of exciton\nstates in the nanoparticles. Our results provide an understanding of the\nphysics of Cu$_2$O Rydberg excitons in confined dimensions.",
        "positive": "Aharonov-Bohm effect of excitons in nano-rings: The magnetic field effects on excitons in an InAs nano-ring are studied\ntheoretically. By numerically diagonalizing the effective-mass Hamiltonian of\nthe problem, which can be separated into terms in centre-of-mass and relative\ncoordinates, we calculate the low-lying exciton energy levels and oscillator\nstrengths as a function of the width of the ring and the strength of the\nexternal magnetic field. The analytical results are obtained for a narrow-width\nnano-ring in which the radial motion is the fastest one and adiabatically\ndecoupled from the azimuthal motions. It is shown that in the presence of\nCoulomb correlation, the so called Aharonov-Bohm effect of excitons exists in a\nfinite (but small) width nano-ring. However, when the ring width becomes large,\nthe non-simply-connected geometry of nano-rings is destroyed and in turn yields\nthe suppression of Aharonov-Bohm effect. The conditional probability\ndistribution calculated for the low-lying exction states allows identification\nof the presence of Aharonov-Bohm effect. The linear optical susceptibility is\nalso calculated as a function of the magnetic field, to be confronted with the\nfuture measurements of optical emission experiments on InAs nano-rings."
    },
    {
        "anchor": "Non-Markovian Transmission through Two Quantum Dots Connected by a\n  Continuum: We consider a transport setup containing a double-dot connected by a\ncontinuum. Via an exact solution of the time-dependent Schr\\\"odinger equation,\nwe demonstrate a highly non-Markovian quantum-coherence-mediated transport\nthrough this dot-continuum-dot (DCD) system, which is in contrast with the\ncommon premise since in typical case a quantum particle does not reenter the\nsystem of interest once it irreversibly decayed into a continuum (such as the\nspontaneous emission of a photon). We also find that this DCD system supports\nan unusual steady state with unequal source and drain currents, owing to\nelectrons irreversibly entering the continuum and floating there.",
        "positive": "Semiconductor thermal and electrical properties decoupled by localized\n  phonon resonances: Thermoelectric materials convert heat into electricity through thermally\ndriven charge transport in solids, or vice versa for cooling. To be competitive\nwith conventional energy-generation technologies, a thermoelectric material\nmust possess the properties of both an electrical conductor and a thermal\ninsulator. However, these properties are normally mutually exclusive because of\nthe interconnection of the scattering mechanisms for charge carriers and\nphonons. Recent theoretical investigations on sub-device scales have revealed\nthat silicon membranes covered by nanopillars exhibit a multitude of local\nphonon resonances, spanning the full spectrum, that couple with the\nheat-carrying phonons in the membrane and collectively cause a reduction in the\nin-plane thermal conductivity$-$while, in principle, not affecting the\nelectrical properties because the nanopillars are external to the pathway of\nvoltage generation and charge transport. Here this effect is demonstrated\nexperimentally for the first time by investigating device-scale suspended\nsilicon membranes with GaN nanopillars grown on the surface. The nanopillars\ncause up to 21 % reduction in the thermal conductivity while the electrical\nconductivity and the Seebeck coefficient remain unaffected, thus demonstrating\nan unprecedented decoupling in the semiconductor's thermoelectric properties.\nThe measured thermal conductivity behavior for coalesced nanopillars and\ncorresponding lattice-dynamics calculations provide further evidence that the\nreductions are mechanistically tied to the phonon resonances. This finding\nbreaks a longstanding trade-off between competing properties in\nthermoelectricity and paves the way for engineered high-efficiency solid-state\nenergy recovery and cooling."
    },
    {
        "anchor": "Z2 peak of noise correlations in a quantum spin Hall insulator: We investigate the current noise correlations at a quantum point contact in a\nquantum spin Hall structure, focusing on the effect of a weak magnetic field in\nthe presence of disorder. For the case of two equally biased terminals we\ndiscover a robust peak: the noise correlations vanish at $B = 0 $ and are\nnegative for $B\\not = 0 $. We find that the character of this peak is\nintimately related to the interplay between time reversal symmetry and the\nhelical nature of the edge states and call it the Z2 peak.",
        "positive": "Edelstein effects, spin-transfer torque, and spin pumping caused by\n  pristine surface states of topological insulators: The Edelstein effect caused by the pristine surface states of\nthree-dimensional topological insulators is investigated by means of a\nsemiclassical approach. The combined effect of random impurity scattering and\nthe spin-momentum locking of the gapless Dirac cone yields a current-induced\nsurface spin accumulation independent from chemical potential and temperature.\nIn a nearby ferromagnet that does not make direct contact with the topological\ninsulator, the bound state nature of the pristine surface state causes a\nspin-transfer torque that is entirely field-like, whose magnitude is highly\ninfluenced by the interface cleanliness and the quantum well state of the\nferromagnet. Through incorporating quantum tunneling into Bloch equation, the\nspin pumping mediated by the pristine surface state is shown to be described by\nthe same spin mixing conductance as the spin-transfer torque, and a\nsemiclassical approach is proposed to explain the inverse Edelstein effect that\nconverts the spin pumping spin current into a charge current. Consistency of\nthese results with various experiments will be elaborated in detail."
    },
    {
        "anchor": "Spin Relaxation Anisotropy in Two-Dimensional Semiconductor Systems: Spin relaxation is investigated theoretically in two-dimensional systems.\nVarious semiconductor structures of both n- and p-types are studied in detail.\nThe most important spin relaxation mechanisms are considered. The spin\nrelaxation times are calculated taking into account the contributions to the\nspin--orbit interaction due to both the bulk inversion asymmetry and the\nstructure inversion asymmetry. It is shown that in-plane anisotropy of electron\nspin relaxation appears in III--V asymmetrical heterostructures. This\nanisotropy may be controlled by external parameters, and the spin relaxation\ntimes differ by several orders of magnitude.",
        "positive": "Thermodynamic properties of tunneling quasiparticles in graphene-based\n  structures: Thermodynamic properties of quasiparticles in a graphene-based structures are\ninvestigated. Two graphene superconducting layers (one superconducting\ncomponent is placed on the top layeredgraphene structure and the other\ncomponent in the bottom) separated by oxide dielectric layers and one normal\ngraphene layer in the middle. The quasiparticle flow emerged due to external\ngate voltage, we considered it as a gas of electron-hole pairs whose components\nbelong to different layers. This is a striking result in view of the complexity\nof these systems: we have established that specific heat exhibits universal\n(-T3) behaviour at low T, independent from the gate voltage and the\nsuperconducting gap. The experimental observation of this theoretical\nprediction would be an important step towards our understanding of critical\nmassless matter."
    },
    {
        "anchor": "Commensurability oscillations in a quasi-two-dimensional electron gas\n  subjected to strong in-plane magnetic field: We report on a theoretical study of the commensurability oscillations in a\nquasi-two-dimensional electron gas modulated by a unidirectional periodic\npotential and subjected to tilted magnetic fields with a strong in-plane\ncomponent. As a result of coupling of the in-plane field component and the\nconfining potential in the finite-width quantum well, the originally circular\ncyclotron orbits become anisotropic and tilted out of the sample plane. A\nquasi-classical approach to the theory, that relates the magneto-resistance\noscillations to the guiding-center drift, is extended to this case.",
        "positive": "Ferromagnetic proximity effect in F-QDot-S device: Ferromagnetic proximity effect is studied in InAs nanowire (NW) based quantum\ndots (QD) strongly coupled to a ferromagnetic (F) and a superconducting (S)\nlead. The influence of the F lead is detected through the splitting of the\nspin-1/2 Kondo resonance. We show that the F lead induces a local exchange\nfield on the QD, which has varying amplitude and a sign depending on the charge\nstates. The interplay of the F and S correlations generates an exchange field\nrelated supgap feature. This novel mini-gap allows now the visualization of the\nexchange field also in even charge states"
    },
    {
        "anchor": "Voltage-controlled inversion of tunnel magnetoresistance in epitaxial\n  Nickel/Graphene/MgO/Cobalt junctions: We report on the fabrication and characterization of vertical spin-valve\nstructures using a thick epitaxial MgO barrier as spacer layer and a\ngraphene-passivated Ni film as bottom ferromagnetic electrode. The devices show\nrobust and scalable tunnel magnetoresistance, with several changes of sign upon\nvarying the applied bias voltage. These findings are explained by a model of\nphonon-assisted transport mechanisms that relies on the peculiarity of the band\nstructure and spin density of states at the hybrid graphene|Ni interface.",
        "positive": "Theory of exciton fine structure in semiconductor quantum dots: quantum\n  dot anisotropy and lateral electric field: Theory of exciton fine structure in semiconductor quantum dots and its\ndependence on quantum dot anisotropy and external lateral electric field is\npresented. The effective exciton Hamiltonian including long range electron-hole\nexchange interaction is derived within the k*p effective mass approximation\n(EMA). The exchange matrix elements of the Hamiltonian are expressed explicitly\nin terms of electron and hole envelope functions. The matrix element\nresponsible for the \"bright\" exciton splitting is identified and analyzed. An\nexcitonic fine structure for a model quantum dot with quasi- two-dimensional\nanisotropic harmonic oscillator (2DLAHO) confining potential is analyzed as a\nfunction of the shape anisotropy, size and applied lateral electric field."
    },
    {
        "anchor": "Molecular Transport Junctions: Vibrational Effects: Introduction (2)\n  Experimental background: Test beds (8)\n  Theoretical approaches: A microscopic model(10) The electron-phonon\ncoupling(14)Time and energy scales(15) Theoretical methods(19)Numerical\ncalculations(28)\n  Incoherent vs. coherent transport (28)\n  Inelastic tunneling spectroscopy: Experimental background(31) Theoretical\nconsiderations:the weak coupling limit(36) Theoretical considerations:\nmoderately strong coupling(41)Comparison of approximation schemes(48)Asymmetry\nin IETS(51)The origin of dips in IETS signals(53)Computational approaches (56)\n  Effects of electron-electron(e-e)interactions (63)\n  Noise (66)\n  Non-linear conductance phenomena (73)\n  Heating and heat conduction: General considerations(77) Heat generation(81)\nHeat conduction(85) Junction temperature(88)\n  Current induced reactions (91)\n  Summary and outlook (91)",
        "positive": "Tunable exciton interactions in optical lattices with polar molecules: Rotational excitation of polar molecules trapped in an optical lattice gives\nrise to rotational excitons. Here we show that non-linear interactions of such\nexcitons can be controlled by an electric field. The exciton--exciton\ninteractions can be tuned to induce exciton pairing, leading to the formation\nof biexcitons. Tunable non-linear interactions between excitons can be used for\nmany applications ranging from the controlled preparation of entangled\nquasiparticles to the study of polaron interactions and the effects of\nnon-linear interactions on quantum energy transport in molecular aggregates."
    },
    {
        "anchor": "Mean-field Phase Diagram of Two-Dimensional Electrons with Disorder in a\n  Weak Magnetic Field: We study two-dimensional interacting electrons in a weak perpendicular\nmagnetic field with the filling factor $\\nu \\gg 1$ and in the presence of a\nquenched disorder. In the framework of the Hartree-Fock approximation, we\nobtain the mean-field phase diagram for the partially filled highest Landau\nlevel. We find that the CDW state can exist if the Landau level broadening\n$1/2\\tau $ does not exceed the critical value $1/2\\tau_{c}=0.038\\omega_{H}$.\nOur analysis of weak crystallization corrections to the mean-field results\nshows that these corrections are of the order of $(1/\\nu)^{2/3}\\ll 1$ and\ntherefore can be neglected.",
        "positive": "$q$th-root non-Hermitian Floquet topological insulators: Floquet phases of matter have attracted great attention due to their\ndynamical and topological nature that are unique to nonequilibrium settings. In\nthis work, we introduce a generic way of taking any integer $q$th-root of the\nevolution operator $U$ that describes Floquet topological matter. We further\napply our $q$th-rooting procedure to obtain $2^n$th- and $3^n$th-root first-\nand second-order non-Hermitian Floquet topological insulators (FTIs). There, we\nexplicitly demonstrate the presence of multiple edge and corner modes at\nfractional quasienergies $\\pm(0,1,...2^{n})\\pi/2^{n}$ and\n$\\pm(0,1,...,3^{n})\\pi/3^{n}$, whose numbers are highly controllable and\ncapturable by the topological invariants of their parent systems. Notably, we\nobserve non-Hermiticity induced fractional-quasienergy corner modes and the\ncoexistence of non-Hermitian skin effect with fractional-quasienergy edge\nstates. Our findings thus establish a framework of constructing an intriguing\nclass of topological matter in Floquet open systems."
    },
    {
        "anchor": "Dynamic effect of electron-number parity in metal nanoparticles: Parity is a ubiquitous notion in science and serves as a fundamental\nprinciple for describing a physical system. Nanometer-scale metal objects are\npredicted to show dramatic differences in physical properties depending on the\nelectron-number parity. However, the identification of the electron-number\nparity effects in real metal nanoparticles has remained elusive because of the\nvariations in various features of nanoparticles. Here we report the nuclear\nmagnetic resonance (NMR) detection of the dynamic effect of the electron-number\nparity in silver nanoparticles. With theoretical modeling of the NMR relaxation\nin silver nanoparticles, the measured nuclear spin-lattice relaxation rate is\nfound to be proportional to the electron-number-parity-dependent susceptibility\nand to the temperature. This observation demonstrates the\nelectron-number-parity-governed spin dynamics in silver nanoparticles.",
        "positive": "The Effects of Interfacial Recombination and Injection Barrier on the\n  Electrical Characteristics of Perovskite Solar Cells: Charge carrier recombination in the perovskite solar cells (PSCs) has a deep\ninfluence on the electrical performance, such as open circuit voltage, short\ncircuit current, fill factor and ultimately power conversion efficiency. The\nimpacts of injection barrier, recombination channels, doping properties of\ncarrier transport layers and light intensity on the performance of PSCs are\ntheoretically investigated by drift-diffusion model in this work. The results\nindicate that due to the injection barrier at the interfaces of perovskite and\ncarrier transport layer, the accumulated carriers modify the electric field\ndistribution throughout the PSCs. Thus, a zero electric field is generated at a\nspecific applied voltage, with greatly increases the interfacial recombination,\nresulting in a local kink of current density-voltage (J-V) curve. This work\nprovides an effective strategy to improve the efficiency of PSCs by pertinently\nreducing both the injection barrier and interfacial recombination."
    },
    {
        "anchor": "Molecular structure elucidation with charge-state control: The charge state of a molecule governs its physicochemical properties, such\nas conformation, reactivity and aromaticity, with implications for on-surface\nsynthesis, catalysis, photo conversion and applications in molecular\nelectronics. On insulating, multilayer NaCl films we control the charge state\nof organic molecules and resolve their structures in neutral, cationic, anionic\nand dianionic states by atomic force microscopy, obtaining atomic resolution\nand bond-order discrimination using CO functionalized tips. We detect changes\nin conformation, adsorption geometry and bond-order relations for azobenzene,\ntetracyanoquinodimethane and pentacene in multiple charge states. Moreover, for\nporphine we investigate the charge-state-dependent change of aromaticity and\nconjugation pathway in the macrocycle. This work opens the way to studying\nchemical-structural changes of individual molecules for a wide range of charge\nstates.",
        "positive": "Experimental observation and modeling of the impact of traps on static\n  and analog/HF performance of graphene transistors: The trap-induced hysteresis on the performance of a graphene field-effect\ntransistor is experimentally diminished here by applying consecutive\ngate-to-source voltage pulses of opposing polarity. This measurement scheme is\na practical and suitable approach to obtain reproducible device\ncharacteristics. Trap-affected and trap-free experimental data enable a\ndiscussion regarding the impact of traps on static and dynamic device\nperformance. An analytical drain current model calibrated with the experimental\ndata enables the study of the traps effects on the channel potential within the\ndevice. High-frequency figures of merit and the intrinsic gain of the device\nobtained from both experimental and synthetic data with and without hysteresis\nshow the importance of considering the generally overlooked impact of traps for\nanalog and high-frequency applications."
    },
    {
        "anchor": "Similarities and differences in the construction of dispersion laws for\n  charge carriers in semiconductor crystals and adiabatic potentials in\n  molecules: Using the group theory and the method of invariants, it is shown how the\nvibronic potential can be written in a matrix form and the corresponding\nadiabatic potentials can be found. The molecule having $D_{3d}$ symmetry is\nconsidered herein as an example. The symmetries of normal vibrations active in\nJahn-Teller's effect were defined. $E-E$ vibronic interaction was considered to\nobtain vibronic potential energy in a matrix form and thus the adiabatic\npotential. Significant differences are shown in the construction of a secular\nmatrix $D(\\vec{k})$ for defining a dispersion law for charge carriers in the\ncrystals and the matrix of vibronic potential energy, which depends on the\nnormal coordinates of normal vibrations active in Jahn-Teller's effect.\nDispersion law of charge carriers in the vicinity of $\\Gamma$ point of\nBrillouin zone of the crystal with $D_{3d}^2$ symmetry was considered as an\nexample.",
        "positive": "Subdiffractional focusing and guiding of polaritonic rays in a natural\n  hyperbolic material: Uniaxial materials whose axial and tangential permittivities have opposite\nsigns are referred to as indefinite or hyperbolic media. In such materials\nlight propagation is unusual, leading to novel and often non-intuitive optical\nphenomena. Here we report infrared nano-imaging experiments demonstrating that\ncrystals of hexagonal boron nitride (hBN), a natural mid-infrared hyperbolic\nmaterial, can act as a \"hyper-focusing lens\" and as a multi-mode waveguide. The\nlensing is manifested by subdiffractional focusing of phonon-polaritons\nlaunched by metallic disks underneath the hBN crystal. The waveguiding is\nrevealed through the modal analysis of the periodic patterns observed around\nsuch launchers and near the sample edges. Our work opens new opportunities for\nanisotropic layered insulators in infrared nanophotonics complementing and\npotentially surpassing concurrent artificial hyperbolic materials with lower\nlosses and higher optical localization."
    },
    {
        "anchor": "Prospects of Hysteresis-Free Abrupt Switching (0mV/dec) in Landau\n  Switches: Sub-threshold swing (S) defines the sharpness of ON-OFF switching of a Field\nEffect Transistor (FET) with S=0 corresponding to abrupt switching\ncharacteristics. While thermodynamics dictates S to be greater than or equal to\n60mV/dec for classical FETs, \"Landau switches\" use inherently unstable gate\ninsulators to achieve abrupt switching. Unfortunately, S=0 switching is always\nachieved at the expense of an intrinsic hysteresis, making these switches\nunsuitable for low-power applications. The fundamental question therefore\nremains: Under what condition, hysteresis-free abrupt switching can be achieved\nin a Landau switch? In this paper, we first provide an intuitive classification\nof all charge based switches in terms of their energy landscapes and identify\ntwo-well energy landscape as the characteristic feature of Landau switches. We\nthen use nanoelectromechanical field effect transistor (NEMFET) as an\nillustrative example of a Landau switch and conclude that a flat energy\nlandscape is essential for hysteresis-free abrupt switching. In contrast, a\nhysteresis-free smooth sub-60mV/dec switching is obtained by stabilizing the\nunstable gate insulator in its unstable regime. Our conclusions have broad\nimplications and may considerably simplify the design of next charge based\nlogic switch.",
        "positive": "$\u03bd=1/2$ Fractional Quantum Hall Effect in Tilted Magnetic Fields: Magnetotransport measurements on two-dimensional electrons confined to wide\nGaAs quantum wells reveal a remarkable evolution of the ground state at filling\nfactor $\\nu=1/2$ as we tilt the sample in the magnetic field. Starting with a\ncompressible state at zero tilt angle, a strong $\\nu=1/2$ fractional quantum\nHall state appears at intermediate angles. At higher angles an insulating phase\nsurrounds this state and eventually engulfs it at the highest angles. This\nevolution occurs because the parallel component of the field renders the charge\ndistribution increasingly bilayer-like."
    },
    {
        "anchor": "Decoherence of intermolecular entanglement in exchange-coupled\n  nanomagnets: We theoretically investigate the hyperfine-induced decoherence in a pair of\nspin-cluster qubits, consisting of two exchange-coupled heterometallic wheels.\nWe identify two distinct regimes in the decoherence of intermolecular\nentanglement and show that this can be substantially recovered through\ndynamical decoupling. Different chemical elements and physical processes are\nresponsible for the decoherence of the singlet-triplet superposition, resulting\nin a wider tunability of its decoherence time.",
        "positive": "Many-body filling-factor dependent renormalization of Fermi velocity in\n  graphene in strong magnetic field: We present the theory of many-body corrections to cyclotron transition\nenergies in graphene in strong magnetic field due to Coulomb interaction,\nconsidered in terms of the renormalized Fermi velocity. A particular emphasis\nis made on the recent experiments where detailed dependencies of this velocity\non the Landau level filling factor for individual transitions were measured.\nTaking into account the many-body exchange, excitonic corrections and\ninteraction screening in the static random-phase approximation, we successfully\nexplained the main features of the experimental data, in particular that the\nFermi velocities have plateaus when the 0th Landau level is partially filled\nand rapidly decrease at higher carrier densities due to enhancement of the\nscreening. We also explained the features of the nonmonotonous filling-factor\ndependence of the Fermi velocity observed in the earlier cyclotron resonance\nexperiment with disordered graphene by taking into account the disorder-induced\nLandau level broadening."
    },
    {
        "anchor": "How close can one approach the Dirac point in graphene experimentally?: The above question is frequently asked by theorists who are interested in\ngraphene as a model system, especially in context of relativistic quantum\nphysics. We offer an experimental answer by describing electron transport in\nsuspended devices with carrier mobilities of several 10^6 cm^2V^-1s^-1 and with\nthe onset of Landau quantization occurring in fields below 5 mT. The observed\ncharge inhomogeneity is as low as \\approx10^8 cm^-2, allowing a neutral state\nwith a few charge carriers per entire micron-scale device. Above liquid helium\ntemperatures, the electronic properties of such devices are intrinsic, being\ngoverned by thermal excitations only. This yields that the Dirac point can be\napproached within 1 meV, a limit currently set by the remaining charge\ninhomogeneity. No sign of an insulating state is observed down to 1 K, which\nestablishes the upper limit on a possible bandgap.",
        "positive": "The Effective Bosonic Hamiltonian for Excitons Reconsidered: The effective bosonic hamiltonian for excitons, extensively quoted up to now,\ncannot be correct because it is (surprisingly) non-hermitian. The oversight\nphysically originates from the intrinsic difficulty of properly defining\nelectron-hole interactions between excitons when dealing with exchange terms.\nBy using our commutation technique, we show that the fermionic character of the\nexcitons cannot be forced into a dressed Coulomb interaction only : The\neffective bosonic hamiltonian must contain purely fermionic terms of the same\norder as the Coulomb terms. They are necessary to ensure hermiticity, and they\ndo not reduce to a two-body interaction, Pauli exclusion being N-body by\nessence."
    },
    {
        "anchor": "Determination of the phase shifts for interacting electrons connected to\n  reservoirs: We describe a formulation to deduce the phase shifts, which determine the\nground-state properties of interacting quantum-dot systems with the inversion\nsymmetry, from the fixed-point eigenvalues of the numerical renormalization\ngroup (NRG). Our approach does not assume the specific form of the Hamiltonian\nnor the electron-hole symmetry, and it is applicable to a wide class of quantum\nimpurities connected to noninteracting leads. We apply the method to a triple\ndot which is described by a three-site Hubbard chain connected to two\nnoninteracting leads, and calculate the dc conductance away from half-filling.\nThe conductance shows the typical Kondo plateaus of Unitary limit in some\nregions of the gate voltages, at which the total number of electrons N_el in\nthe three dots is odd, i.e., N_el =1, 3 and 5. In contrast, the conductance\nshows a wide minimum in the gate voltages corresponding to even number of\nelectrons, N_el = 2 and 4.\n  We also discuss the parallel conductance of the triple dot connected\ntransversely to four leads, and show that it can be deduced from the two phase\nshifts defined in the two-lead case.",
        "positive": "Electrical driving single barrier spin cell: We propose a spin cell based on photon-assisted tunneling through a\nconventional semiconductor barrier. The Dresselhaus spin-orbit interaction is\nincluded to break the spin rotation symmetry. Due to the in-plane electric\nfield induced asymmetric momentum distribution in one lead, continuous flows of\nspin currents are driven through a barrier by a AC field. The net charge\ncurrent remains zero. The spin current via photon-assisted tunneling can be\nreadily adjusted via tuning the AC frequency or the in-plane electric field.\nThis device may function as an ideal spin cell to supply spin currents in the\nspintronics circuit."
    },
    {
        "anchor": "Resonant excitonic emission of a single quantum dot in the Rabi regime: We report on coherent resonant emission of the fundamental exciton state in a\nsingle semiconductor GaAs quantum dot. Resonant regime with picoseconde laser\nexcitation is realized by embedding the quantum dots in a waveguiding\nstructure. As the pulse intensity is increased, Rabi oscillation is observed up\nto three periods. The Rabi regime is achieved owing to an enhanced light-matter\ncoupling in the waveguide. This is due to a \\emph{slow light effect}\n($c/v_{g}\\simeq 3000$), occuring when an intense resonant pulse propagates in a\nmedium. The resonant control of the quantum dot fundamental transition opens\nnew possibilities in quantum state manipulation and quantum optics experiments\nin condensed matter physics.",
        "positive": "Studies of resistance switching effects in metal/YBa2Cu3O7-x interface\n  junctions: Current-voltage characteristics of planar junctions formed by an epitaxial\nc-axis oriented YBa2Cu3O7-x thin film micro-bridge and Ag counter-electrode\nwere measured in the temperature range from 4.2 K to 300 K. A hysteretic\nbehavior related to switching of the junction resistance from a high-resistive\nto a low-resistive state and vice-versa was observed and analyzed in terms of\nthe maximal current bias and temperature dependence. The same effects were\nobserved on a sub-micrometer scale YBa2Cu3O7-x thin film - PtIr point contact\njunctions using Scanning Tunneling Microscope. These phenomena are discussed\nwithin a diffusion model, describing an oxygen vacancy drift in YBa2Cu3O7-x\nfilms in the nano-scale vicinity of the junction interface under applied\nelectrical fields."
    },
    {
        "anchor": "Non-equilibrium Green's function study of magneto-conductance features\n  and oscillations in clean and disordered nanowires: We explore various aspects of magneto-conductance oscillations in\nsemiconductor nanowires, developing quantum transport models based on the\nnon-equilibrium Green's function formalism. In the clean case, Aharonov-Bohm\n(AB - h/e) oscillations are found to be dominant, contingent upon the surface\nconfinement of electrons in the nanowire. We also numerically study disordered\nnanowires of finite length, bridging a gap in the existing literature. By\nvarying the nanowire length and disorder strength, we identify the transition\nwhere Al'tshuler-Aronov-Spivak (AAS - h/2e) oscillations start dominating,\nnoting the effects of considering an open system. Moreover, we demonstrate how\nthe relative magnitudes of the scattering length and the device dimensions\ngovern the relative dominance of these harmonics with energy, revealing that\nthe AAS oscillations emerge and start dominating from the center of the band,\nmuch higher in energy than the conduction band-edge. We also show the ways of\nsuppressing the oscillatory components (AB and AAS) to observe the\nnon-oscillatory weak localization corrections, noting the interplay of\nscattering, incoherence/dephasing, the geometry of electronic distribution, and\norientation of magnetic field. This is followed by a study of surface roughness\nwhich shows contrasting effects depending on its strength and type, ranging\nfrom magnetic depopulation to strong AAS oscillations. Subsequently, we show\nthat dephasing causes a progressive degradation of the higher harmonics,\nexplaining the re-emergence of the AB component even in long and disordered\nnanowires. Lastly, we show that our model qualitatively reproduces the\nexperimental magneto-conductance spectrum in [Holloway et al, PRB 91, 045422\n(2015)] reasonably well while demonstrating the necessity of\nspatial-correlations in the disorder potential, and dephasing.",
        "positive": "Chiral topological insulating phases from three-dimensional nodal loop\n  semimetals: We identify a topological Z index for three dimensional chiral insulators\nwith P*T symmetry where two Hamiltonian terms define a nodal loop. Such systems\nmay belong in the AIII or DIII symmetry class. The Z invariant is a winding\nnumber assigned to the nodal loop and has a correspondence to the geometric\nrelation between the nodal loop and the zeroes of the gap terms. Dirac cone\nedge states under open boundary conditions are in correspondence with the\nwinding numbers assigned to the nodal loops. We verify our method with the\nlow-energy effective Hamiltonian of a three-dimensional material of topological\ninsulators in the Bi$_2$Te$_3$ family."
    },
    {
        "anchor": "Casimir (vacuum) energy in planar QED with strong coupling: The essentially non-perturbative vacuum polarization effects, caused by an\nextended external supercritical Coulomb source, are explored for a planar\nDirac-Coulomb (DC) system with strong coupling (similar to graphene and\ngraphene-based heterostructures). Taking account of results, obtained in\n\\cite{partI2018} for the induced charge density $\\rho_{VP}(\\vec{r})$, in the\npresent paper the evaluation of the Casimir (vacuum) energy $\\mathcal{E}_{VP}$\nis presented. The main result is that for a wide range of the system parameters\nin the overcritical region $\\mathcal{E}_{VP}$ turns out to be a rapidly\ndecreasing negative function $\\sim - Z^3/R_0\\, $ with $Z\\, , R_0$ being the\ncharge and the size of the external source. By an explicit calculation the\npossibility for complete screening of the electrostatic reflection self-energy\nof the external source by such polarization effects for $Z \\gg Z_{cr,1}$ is\ndemonstrated. The dependence of the Casimir energy on the screening of the\nCoulomb asymptotics of the external source at some $R_1>R_0$ is also explored\nin detail, and some peculiar effects in the partial channels with the lowest\nrotational numbers $m_j=\\pm 1/2\\, , \\pm3/2$ in the screened case are also\ndiscussed.",
        "positive": "Spectrally enhancing near-field radiative transfer between gold gratings\n  by exciting magnetic polariton in nanometric vacuum gaps: In the present work, we theoretically demonstrate that near field radiative\ntransport between one dimensional periodic grating microstructures separated by\nnanometer vacuum gaps can be spectrally enhanced by exciting magnetic\npolariton. Fluctuational electrodynamics that incorporates scattering matrix\ntheory with rigorous coupled wave analysis is employed to exactly calculate the\nnear field radiative flux between two gold gratings. Besides the well known\ncoupled surface plasmon polaritons, the radiative flux can be also spectrally\nenhanced due to magnetic polariton, which is excited in the gap between gold\nridges. The mechanisms of magnetic polariton in the near field radiative\ntransport are elucidated in detail, while the unusual enhancement cannot be\npredicted by either the Derjaguin or effective medium approximations. The\neffects of vacuum gap distance and grating geometry parameters between the two\ngratings are investigated. The findings will open up a new way to control near\nfield radiative transfer by magnetic polariton with micro or nanostructured\nmetamaterials."
    },
    {
        "anchor": "Magnetic forces and localized resonances in electron transfer through\n  quantum rings: We study the current flow through semiconductor quantum rings. In high\nmagnetic field the current is usually injected to the arm of the ring preferred\nby classical magnetic forces. However, for narrow magnetic field intervals that\nappear periodically on the magnetic field scale the current is injected to the\nother arm of the ring. We indicate that the appearance of the anomalous --\nnon-classical -- current circulation results from Fano interference involving\nlocalized resonant states. The identification of the Fano interference is based\non the comparison of the solution of the scattering problem with the results of\nthe stabilization method. The latter employs the bound-state type calculations\nand allows to extract both the energy of metastable states localized within the\nring and the width of resonances by analysis of the energy spectrum of a finite\nsize system in function of its length. The Fano resonances involving states of\nanomalous current circulation become extremely narrow on both magnetic field\nand energy scales. This is consistent with the orientation of the Lorentz force\nthat tends to keep the electron within the ring and thus increases the lifetime\nof the electron localization within the ring. Absence of periodic Fano\nresonances in electron transfer probability through a quantum ring containing\nan elastic scatterer is also explained.",
        "positive": "Failure of conductance quantization in two-dimensional topological\n  insulators due to non-magnetic impurities: Despite topological protection and the absence of magnetic impurities,\ntwo-dimensional topological insulators display quantized conductance only in\nsurprisingly short channels, which can be as short as 100 nm for atomically\nthin materials. We show that the combined action of short-range nonmagnetic\nimpurities located near the edges and on site electron-electron interactions\neffectively creates noncollinear magnetic scatterers, and, hence, results in\nstrong backscattering. The mechanism causes deviations from quantization even\nat zero temperature and for a modest strength of electron-electron\ninteractions. Our theory provides a straightforward conceptual framework to\nexplain experimental results, especially those in atomically thin crystals,\nplagued with short-range edge disorder."
    },
    {
        "anchor": "High speed nanotribology with quartz crystal resonators via Atomic Force\n  Microscopy: Friction measurements in the range of several meters per second are still of\ngreat interests. With the atomic force microscopy (AFM), the oscilaltion\nsituation of the quartz crystal resonators of 3MHz resonance frequency are\nstudied. And the oscillation speed could reach up to several m/s. Then the\nfriction measurements are carried out on the Fischer Pattern, which is prepared\non the quartz crystal resonator. In this article, we present how to measure the\noscillation speeds of the quartz crystal resonator and the friction\nmeasurements under different designs. Calibration method and the calculation\nmethods are also discussed in details. Although there are errors in the AFM\nmeasurements due to the setup itself and the oscillating quartz which could\nhighly affect the sharpness of the cantilever tip, the results indicate that\nthe local friction coefficients with oscillation are higher than that without\noscillation.",
        "positive": "Interplay between electron spin and orbital pseudospin in double quantum\n  dots: We investigate theoretically spin and orbital pseudospin magnetic properties\nof a molecular orbital in parabolic and elliptic double quantum dots (DQDs). In\nour many body calculation we include intra- and inter-dot electron-electron\ninteractions, in addition to the intradot exchange interaction of `p' orbitals.\nWe find for parabolic DQDs that, except for the half or completely filled\nmolecular orbital, spins in different dots are ferromagnetically coupled while\norbital pseudospins are antiferromagnetically coupled. For elliptic DQDs spins\nand pseudospins are either ferromagnetically or antiferromagnetically coupled,\ndepending on the number of electrons in the molecular orbital. We have\ndetermined orbital pseudospin quantum numbers for the groundstates of elliptic\nDQDs. An experiment is suggested to test the interplay between orbital\npseudospin and spin magnetism."
    },
    {
        "anchor": "Polarisation control of optically pumped terahertz lasers: Optical pumping of excited exciton states in semiconductor quantum wells is a\ntool for realisation of ultra-compact terahertz (THz) lasers based on\nstimulated optical transition between excited (2p) and ground (1s) exciton\nstate. We show that the probability of two-photon absorption by a 2p-exciton is\nstrongly dependent on the polarisation of both photons. Variation of the\nthreshold power for THz lasing by a factor of 5 is predicted by switching from\nlinear to circular pumping. We calculate the polarisation dependence of the THz\nemission and identify photon polarisation configurations for achieving maximum\nTHz photon generation quantum efficiency.",
        "positive": "Nanowires for heat conversion: This review focuses on the investigation and enhancement of the\nthermoelectric properties of semiconducting nanowires (NWs). NWs are\nnanostructures with typical diameters between few to hundreds of nm and length\nof few to several microns, exhibiting a high surface-to-volume ratio. Nowadays\nan extraordinary control over their growth has been achieved, enabling also the\nintegration of different types of heterostructures, which can lead to the\nengineering of the functional properties of the NWs. In this review, we discuss\nall concepts which have been presented and achieved so far for the improvements\nof the thermoelectric performances of semiconducting NWs. Furthermore, we\npresent a brief survey of the experimental methods which enable the\ninvestigation of the thermoelectric properties of these nanostructures."
    },
    {
        "anchor": "Unconventional charge-spin conversion in Weyl-semimetal WTe2: An outstanding feature of topological quantum materials is their novel spin\ntopology in the electronic band structures with an expected large\ncharge-to-spin conversion efficiency. Here, we report a charge current-induced\nspin polarization in the type-II Weyl semimetal candidate WTe2 and efficient\nspin injection and detection in a graphene channel up to room temperature.\nContrary to the conventional spin Hall and Rashba-Edelstein effects, our\nmeasurements indicate an unconventional charge-to-spin conversion in WTe2,\nwhich is primarily forbidden by the crystal symmetry of the system. Such a\nlarge spin polarization can be possible in WTe2 due to a reduced crystal\nsymmetry combined with its large spin Berry curvature, spin-orbit interaction\nwith a novel spin-texture of the Fermi states. We demonstrate a robust and\npractical method for electrical creation and detection of such a spin\npolarization using both charge-to-spin conversion and its inverse phenomenon\nand utilized it for efficient spin injection and detection in a graphene\nchannel up to room temperature. These findings open opportunities for utilizing\ntopological Weyl materials as non-magnetic spin sources in allelectrical van\nder Waals spintronic circuits and for low-power and high-performance\nnon-volatile spintronic technologies.",
        "positive": "Nodal pair-density-waves from quarter-metal in crystalline graphene\n  multilayers: Crystalline graphene heterostructures, namely Bernal bilayer and rhombohedral\ntrilayer graphene, subject to electric displacement fields, display a rich\nconfluence of competing orders, resulting in a valley-degenerate,\nspin-polarized half-metal at moderate doping, and a spin- and valley-polarized\nquarter-metal at low doping. Here we show that the annular Fermi surface of\nsuch a quarter-metal can be susceptible toward the nucleation of a unique spin\nand valley polarized superconducting state, accommodating interlayer Cooper\npairs that break the translational symmetry, giving rise to a Kekul\\'e or\ncolumnar pair-density-wave. The superconducting ground state produces isolated\nFermi pockets of neutral Majorana fermions, featuring a three-fold rotational\nsymmetry, resulting in power-law scaling physical observables with temperature\n($T$), such as specific heat $C_v \\sim T$."
    },
    {
        "anchor": "The positive piezoconductive effect in graphene: As the thinnest conductive and elastic material, graphene is expected to play\na crucial role in post-Moore era. Besides applications on electronic devices,\ngraphene has shown great potential for nano-electromechanical systems. While\ninterlayer interactions play a key role in modifying the electronic structures\nof layered materials, no attention has been given to their impact on\nelectromechanical properties. Here we report the positive piezoconductive\neffect observed in suspended bi- and multi-layer graphene. The effect is highly\nlayer number dependent and shows the most pronounced response for tri-layer\ngraphene. The effect, and its dependence on the layer number, can be understood\nas resulting from the strain-induced competition between interlayer coupling\nand intralayer transport, as confirmed by the numerical calculations based on\nthe non-equilibrium Green's function method. Our results enrich the\nunderstanding of graphene and point to layer number as a powerful tool for\ntuning the electromechanical properties of graphene for future applications.",
        "positive": "Electro-optical properties of excitons in Cu$_2$O quantum wells: II\n  continuum states: We present theoretically calculated optical functions for Cu$_2$O quantum\nwell (QW) with Rydberg excitons in an external, homogeneous electric field\nparallel to the QW planes for the energy region above the gap, suitable to\nobserve the Franz-Keldysh (FK) oscillations. We quantitatively describe the\namplitudes and periodicity of FK modulations and the influence of both Rydberg\nexcitons and confinement effect on this phenomenon."
    },
    {
        "anchor": "Non-adiabatic pumping of single electrons affected by magnetic fields: Non-adiabatic pumping of discrete charges, realized by a dynamical quantum\ndot in an AlGaAs/GaAs heterostructure, is studied under influence of a\nperpendicular magnetic field. Application of an oscillating voltage in the\nGHz-range to one of two top gates, crossing a narrow wire and confining a\nquantum dot, leads to quantized pumped current plateaus in the gate\ncharacteristics. The regime of pumping one single electron is traced back to\nthe diverse tunneling processes into and out-of the dot. Extending the theory\nto multiple electrons allows to investigate conveniently the pumping\ncharacteristics in an applied magnetic field. In this way, a qualitatively\ndifferent behavior between pumping even or odd numbers of electrons is\nextracted.",
        "positive": "Ultra-High-Precision Detection of Single Microwave Photons based on a\n  Hybrid System between Majorana Zero Mode and a Quantum Dot: The ability to detect single photons has become increasingly essential due to\nthe rise of photon-based quantum computing. In this theoretical work, we\npropose a system consisting of a quantum dot (QD) side-coupled to a\nsuperconducting nanowire. The coupling opens a gap in both the QD mode and the\nMajorana zero mode (MZM) at the nanowire edge, enabling photon absorption in\nthe system. We show that the absorbed photoelectron decays via rapid\n(sub-nanosecond to nanosecond) nonradiative heat transfer to the nanowire\nphonon modes rather than by spontaneous emission. Furthermore, we calculate the\ntemperature increase and associated resistance increase induced by the\nabsorption of a photon for a given appropriate set of material and\nenvironmental parameters, yielding a temperature increase in the millikelvin\nrange and a resistance increase in the kiloohm range, vastly exceeding the\nphoton-absorption-induced temperature and resistance increases for competing\n2D-3D hybrid systems by 5 and 9 orders of magnitude, respectively. Lastly, we\ndetermine the detector efficiency and discuss the system density required for\ndeterministic photon number measurement, demonstrating that a photon absorption\nprobability of over 99.9 percent can be achieved for an integrated system\nconsisting of an array of nanowire-QD complexes on-chip inside a cavity. Our\nresults thus provide a basis for a deterministic microwave photon number\ndetector with an unprecedented photon-number-detection resolution."
    },
    {
        "anchor": "Unconventional magnon excitation by off-resonant microwaves: It is widely recognized that a physical system can only respond to a periodic\ndriving significantly when the driving frequency matches the normal mode\nfrequency of the system, which leads to resonance. Off-resonant phenomena are\nrarely considered because of the difficulty to realize strong coupling between\nphysical systems and off-resonant waves. Here we examine the response of a\nmagnetic system to squeezed light and surprisingly find that the magnons are\nmaximally excited when the effective driving frequency is several orders of\nmagnitude larger than the resonant frequency. The generated magnons are\nsqueezed which brings the advantage of tunable squeezing through an external\nmagnetic field. Furthermore, we demonstrate that such off-resonant\nquasi-particle excitation is universal in all the hybrid systems in which the\ncoherent and parametric interaction of bosons exists and that it is purely a\nquantum effect, which is rooted in the quantum fluctuations of particles in the\nsqueezed vacuum. Our findings may provide an unconventional route to study\noff-resonant phenomena and may further benefit the use of hybrid matter-light\nsystems in continuous variable quantum information.",
        "positive": "Symmetry in Full Counting Statistics, Fluctuation Theorem, and Relations\n  among Nonlinear Transport Coefficients in the Presence of a Magnetic Field: We study full counting statistics of coherent electron transport through\nmulti-terminal interacting quantum-dots under a finite magnetic field.\nMicroscopic reversibility leads to the symmetry of the cumulant generating\nfunction, which generalizes the fluctuation theorem in the context of quantum\ntransport. Using this symmetry, we derive the Onsager-Casimir relation in the\nlinear transport regime and universal relations among nonlinear transport\ncoefficients."
    },
    {
        "anchor": "Breakdown of the resistor model of CPP-GMR in magnetic multilayered\n  nanostructures: We study the effect on CPP GMR of changing the order of the layers in a\nmultilayer. Using a tight-binding simple cubic two band model (s-d),\nmagneto-transport properties are calculated in the zero-temperature, zero-bias\nlimit, within the Landauer-Buttiker formalism. We demonstrate that for layers\nof different thicknesses formed from a single magnetic metal and multilayers\nformed from two magnetic metals, the GMR ratio and its dependence on disorder\nis sensitive to the order of the layers. This effect disappears in the limit of\nlarge disorder, where the results of the widely-used Boltzmann approach to\ntransport are restored.",
        "positive": "Thermal noise induced stochastic resonance in self organizing Fe\n  nanoparticle system: The natural world is replete with examples of multistable systems, known to\nrespond to periodic modulations and produce a signal, which exhibits resonance\nwith noise amplitude. This is a concept not demonstrated in pure materials,\nwhich involve a measured physical property. In a thermoremanent magnetization\nexperiment with a common magnetic material, Fe, in the nanoparticulate form, we\nestablish how magnetization in a system of dilute spins during dissipation of\nstored magnetic energy, breaks up into spontaneous oscillatory behavior.\nStarting at 175 K and aided by temperature (stochastic noise) the oscillation\namplitude goes through a maximum, reminiscent of stochastic resonance. Our\nobservation of thermal noise induced coherent resonance is due to intrinsic\nself-organizing magnetic dynamics of the Fe nanoperticle system without\napplying any external periodic force. These results yield new possibilities in\ndesign of magnetic materials and a platform to understand stochastic\ninterference and phase synchronization in neural activity, as models for neural\ncommunication."
    },
    {
        "anchor": "Topological symmetry classes for non-Hermitian models and connections to\n  the bosonic Bogoliubov-de Gennes equation: The Bernard-LeClair (BL) symmetry classes generalize the ten-fold way classes\nin the absence of Hermiticity. Within the BL scheme, time-reversal and\nparticle-hole come in two flavors, and \"pseudo-Hermiticity\" generalizes\nHermiticity. We propose that these symmetries are relevant for the topological\nclassification of non-Hermitian single-particle Hamiltonians and Hermitian\nbosonic Bogoliubov-de Gennes (BdG) models. We show that the spectrum of any\nHermitian bosonic BdG Hamiltonian is found by solving for the eigenvalues of a\nnon-Hermitian matrix which belongs to one of the BL classes. We therefore\nsuggest that bosonic BdG Hamiltonians inherit the topological properties of a\nnon-Hermitian symmetry class and explore the consequences by studying\nsymmetry-protected edge instabilities in a simple 1D system.",
        "positive": "Analytical Expressions and Numerical simulation of single electron\n  spectroscopy: We use the Monte Carlo method to study the two types of devices used in the\ntechnique of single electron spectroscopy and get the C-V curve and I-V curve\nof them. The results compare well to approximate analytical expressions.\nFurthermore, with great prospects, we may take into account such effects as\ncotunneling and coupling between quantum dots through the combination of Monte\nCarlo method and other numerical methods."
    },
    {
        "anchor": "Edge states and ballistic transport in zig-zag graphene ribbons: the\n  role of SiC polytypes: Zig-zag edge graphene ribbons grown on 6H-SiC facets are ballistic\nconductors. It has been assumed that zig-zag graphene ribbons grown on 4H-SiC\nwould also be ballistic. However, in this work we show that SiC polytype\nmatters; ballistic graphene ribbons only grow on 6H SiC. 4H and 4H-passivated\nribbons are diffusive conductors. Detailed photoemmision and microscopy studies\nshow that 6H-SiC sidewalls zig-zag ribbons are metallic with a pair of n-doped\nedge states associated with asymmetric edge terminations, In contrast, 4H-SiC\nzig-zag ribbons are strongly bonded to the SiC; severely distorting the\nribbon's $\\pi$-bands. $\\text{H}_2$-passivation of the 4H ribbons returns them\nto a metallic state but show no evidence of edge states.",
        "positive": "Infrared absorption in a quantum wire in the presence of spin-orbit\n  coupling: a technique to measure different types of spin-orbit interaction\n  strengths: We show that the dominant absorption peak due to inter-subband transition in\na gated quantum wire, with two occupied subbands, will split into a main peak\nand two satellite peaks if both Rashba and Dresselhaus spin-orbit interactions\nare present. One satellite peak will be red-shifted, and the other\nblue-shifted. From the relative intensity of either satellite peak, and the\nmagnitude of the red- or blue-shift, we can determine both Rashba and\nDresselhaus interaction strengths separately, if we also carry out a Hall\nmeasurement to determine the carrier concentration and a quantized conductance\nstep measurement to determine the energy separation between subbands. This\nmethod may be a convenient alternative to usual magneto-transport measurements\nused to measure spin orbit interaction strengths. It is also more powerful\nbecause it allows us to measure the strengths of the two types of interactions\nseparately."
    },
    {
        "anchor": "Direct and Heterodyne Detection of Microwaves in a Metallic Single Wall\n  Carbon Nanotube: This letter reports measurements of microwave (up to 4.5 GHz) detection in\nmetallic single-walled carbon nanotubes. The measured voltage responsivity was\nfound to be 114 V/W at 77K. We also demonstrated heterodyne detection at 1 GHz.\nThe detection mechanism can be explained based on standard microwave detector\ntheory and the nonlinearity of the DC IV-curve. We discuss the possible causes\nof this nonlinearity. While the frequency response is limited by circuit\nparasitics in this measurement, we discuss evidence that indicates that the\neffect is much faster and that applications of carbon nanotubes as terahertz\ndetectors are feasible.",
        "positive": "Observation of fractional quantum Hall effect at even-denominator 1/2\n  and 1/4 fillings in asymmetric wide quantum wells: We report the observation of developing fractional quantum Hall states at\nLandau level filling factors $\\nu = 1/2$ and 1/4 in electron systems confined\nto wide GaAs quantum wells with significantly $asymmetric$ charge\ndistributions. The very large electric subband separation and the highly\nasymmetric charge distribution at which we observe these quantum Hall states,\ntogether with the fact that they disappear when the charge distribution is made\nsymmetric, suggest that these are one-component states, possibly described by\nthe Moore-Read Pfaffian wavefunction."
    },
    {
        "anchor": "A Z$_2$ index of Dirac operator with time reversal symmetry: With time reversal symmetry a Dirac operator has vanishing index and Chern\nnumber. We show that we can nevertheless define a nontrivial Z$_2$ index as\nwell as a corresponding topological invariant given by gauge field, which\nimplies that such a Dirac operator is topologically nontrivial.",
        "positive": "Large N spin quantum Hall effect: We introduce a large N version of the spin quantum Hall transition problem.\nIt is formulated as a problem of Dirac fermions coupled to disorder, whose\nHamiltonian belong to the symmetry class C. The fermions carry spin degrees of\nfreedom valued in the algebra sp(2N), the spin quantum Hall effect\ncorresponding to N=1. Arguments based on renormalization group transformations\nas well as on a sigma model formulation, valid in the large N limit, indicate\nthe existence of a crossover as N varies. Contrary to the N=1 case, the large N\nmodels are shown to lead to localized states at zero energy. We also present a\nsigma model analysis for the system of Dirac fermions coupled to only sp(2N)\nrandom gauge potentials, which reproduces known exact results."
    },
    {
        "anchor": "Conditioning of Piezoresistance Coefficient Extraction: The necessary and sufficient condition for the piezoresistance coefficient\nextraction and conditioning of the extraction problem are considered as a\nproblem of the certain matrix A. This matrix is implied by the stress\ndistribution on the certain test structure. For the given test structure matrix\nA was calculated and the condition number was estimated. Obtained value of\ncondition number shows that proposed test structure gives well-conditioned\nmatrix A. Both the geometrical analysis and numerical estimation of condition\nnumber shows that the problem of extraction is well-conditioned and the test\nstructure is properly designed. For the given condition number the error\npropagation of the input data was considered. For assumed levels of the input\ndata errors, the relative error of piezoresistance coefficient is less than 8%.",
        "positive": "Background force compensation in dynamic atomic force microscopy: Background forces are linear long-range interactions of the cantilever body\nwith its surroundings that must be compensated for in order to reveal\ntip-surface force, the quantity of interest for determining material properties\nin atomic force microscopy. We provide a mathematical derivation of a method to\ncompensate for background forces, apply it to experimental data, and discuss\nhow to include background forces in simulation. Our method, based on\nlinear-response theory in the frequency domain, provides a general way of\nmeasuring and compensating for any background force and it can be readily\napplied to different force reconstruction methods in dynamic AFM."
    },
    {
        "anchor": "Scattering of magnons at graphene quantum-Hall-magnet junctions: Motivated by recent non-local transport studies of quantum-Hall-magnet (QHM)\nstates formed in monolayer graphene's $N=0$ Landau level, we study the\nscattering of QHM magnons by gate-controlled junctions between states with\ndifferent integer filling factors $\\nu$. For the $\\nu=1|-1|1$ geometry we find\nmagnons are weakly scattered by electric potential variation in the junction\nregion, and that the scattering is chiral when the junction lacks a mirror\nsymmetry. For the $\\nu=1|0|1$ geometry, %in which the scattering region\ncontains a $\\nu=0$ canted antiferromagnet, we find that kinematic constraints\ncompletely block magnon transmission if the incident angle exceeds a critical\nvalue. Our results explain the suppressed non-local-voltage signals observed in\nthe $\\nu=1|0|1$ case. We use our theory to propose that valley-waves generated\nat $\\nu=-1|1$ junctions and magnons can be used in combination to probe the\nspin/valley flavor structure of QHM states at integer and fractional filling\nfactors.",
        "positive": "Current hysteresis and memory effect in a molecular quantum dot with\n  strong electron-vibron interaction: Theory of current hysteresis for tunneling through a molecular quantum dot\n(MQD) with strong electron-vibron interactions and attractive electron-electron\ncorrelations is developed. The dot is modeled as a d-fold degenerate energy\nlevel weakly coupled to the leads. The effective attractive interaction between\npolarons in the dot results in a \"switching\" phenomenon in the current-voltage\ncharacteristics when d>2, in agreement with the results for the\nphenomenological negative-U model. The degenerate MQD with strong\nelectron-vibron coupling has two stable current states in certain interval of\nthe bias voltage below some critical temperature."
    },
    {
        "anchor": "Optomechanical Dirac Physics: Recent progress in optomechanical systems may soon allow the realization of\noptomechanical arrays, i.e. periodic arrangements of interacting optical and\nvibrational modes. We show that photons and phonons on a honeycomb lattice will\nproduce an optically tunable Dirac-type band structure. Transport in such a\nsystem can exhibit transmission through an optically created barrier, similar\nto Klein tunneling, but with interconversion between light and sound. In\naddition, edge states at the sample boundaries are dispersive and enable\ncontrolled propagation of photon-phonon polaritons.",
        "positive": "Lateral optical anisotropy of type-II interfaces in the tight-binding\n  approach: We have developed the tight-binding theory to study electronic and optical\nproperties of type-II heterostructures CA/C'A' grown from the zinc-blende\nsemiconductors CA and C'A' along the crystallographic direction [001]. The\nsp^3s* nearest-neighbor tight-binding model with allowance for the spin-orbit\ninteraction is used to calculate the energy states and the in-plane linear\npolarization of the spatially-indirect band-edge photoluminescence of InAs/AlSb\nand ZnSe/BeTe multi-layered structures. The interface parameters for a pair of\nthe nonstandard planes C-A' or C'-A are considered as fitting variables. A wide\nrange of these parameters are shown to allow Tamm-like hole states localized at\nthe interfaces. The theory leads to giant values of the light polarization in\nthe both type-II heterosystems in agreement with existing experimental\nfindings."
    },
    {
        "anchor": "Improving Electric Contacts to Two-Dimensional Semiconductors: Electrical contact resistance to two-dimensional (2D) semiconductors such as\nmonolayer MoS_{2} is a key bottleneck in scaling the 2D field effect\ntransistors (FETs). The 2D semiconductor in contact with three-dimensional\nmetal creates unique current crowding that leads to increased contact\nresistance. We developed a model to separate the contribution of the current\ncrowding from the intrinsic contact resistivity. We show that current crowding\ncan be alleviated by doping and contact patterning. Using Landauer-B\\\"uttiker\nformalism, we show that van der Waals (vdW) gap at the interface will\nultimately limit the electrical contact resistance. We compare our models with\nexperimental data for doped and undoped MoS_{2} FETs. Even with heavy\ncharge-transfer doping of > 2x10^{13} cm^{-2}, we show that the\nstate-of-the-art contact resistance is 100 times larger than the ballistic\nlimit. Our study highlights the need to develop efficient interface to achieve\ncontact resistance of < 10 {\\Omega}.{\\mu}m, which will be ideal for extremely\nscaled devices.",
        "positive": "Wave systems with direct processes and localized losses or gains: the\n  non-unitary Poisson kernel: We study the scattering of waves in systems with losses or gains simulated by\nimaginary potentials. This is done for a complex delta potential that\ncorresponds to a spatially localized absorption or amplification. In the Argand\nplane the scattering matrix moves on a circle $C$ centered on the real axis,\nbut not at the origin, that is tangent to the unit circle. From the numerical\nsimulations it is concluded that the distribution of the scattering matrix,\nwhen measured from the center of the circle $C$, agrees with the non-unitary\nPoisson kernel. This result is also obtained analytically by extending the\nanalyticity condition, of unitary scattering matrices, to the non-unitary ones.\nWe use this non-unitary Poisson kernel to obtain the distribution of\nnon-unitary scattering matrices when measured from the origin of the Argand\nplane. The obtained marginal distributions have an excellent agreement with the\nnumerical results."
    },
    {
        "anchor": "Nitrogen in Silicon for Room Temperature Single Electron Tunneling\n  Devices: Single electron transistor (SET) is an advanced tool to exploit in quantum\ndevices. Working of such devices at room-temperature is essential for practical\nutilization. Dopant based single-electron devices are well studied at\nlow-temperature although a few devices are developed for high-temperature\noperation with certain limitations. Here, we propose and theoretically exhibit\nthat nitrogen (N) donor in silicon is an important candidate for effective\ndesigning of such devices. Theoretical calculation of density-of-states using\nsemi-empirical DFT method indicates that N-donor in silicon has deep ground\nstate compared to a phosphorus (P) donor. N-donor spectrum is explored in\nnano-silicon along with the P-donor. Comparative data of Bohr radius of N-donor\nand P-donor is also reported. The simulated current-voltage characteristics\nconfirm that N-doped device is better suited for SET operation at\nroom-temperature.",
        "positive": "Superparamagnetic dwell times and tuning of switching rates in\n  perpendicular CoFeB/MgO/CoFeB tunnel junctions: Thin electrodes of magnetic tunnel junctions can show superparamagnetism at\nsurprisingly low temperature. We analysed their thermally induced switching for\nvarying temperature, magnetic and electric field. Although the dwell times\nfollow an Arrhenius law, they are orders of magnitude too small compared to a\nmodel of single domain activation. Including entropic effects removes this\ninconsistency and leads to a magnetic activation volume much smaller than that\nof the electrode. Comparing data for varying barrier thickness then allows to\nseparate the impact of Zeman energy, spin-transfer-torque and voltage induced\nanisotropy change on the dwell times. Based on these results, we demonstrate a\ntuning of the switching rates by combining magnetic and electric fields, which\nopens a path for their application in noisy neural networks."
    },
    {
        "anchor": "Phase Diagram of the Low-Density Two-Dimensional Homogeneous Electron\n  Gas: We have used quantum Monte Carlo methods to calculate the zero-temperature\nphase diagram of the two-dimensional homogeneous electron gas. We find a\ntransition from a paramagnetic fluid to an antiferromagnetic triangular Wigner\ncrystal at density parameter r_s=31(1) a.u. and a transition to a ferromagnetic\ncrystal at r_s=38(5) a.u. The fully spin-polarized fluid is never stable. We\nsearched for, but did not find, the ferromagnetic hybrid phase proposed by H.\nFalakshahi and X. Waintal [Phys. Rev. Lett. 94, 046801 (2005)].",
        "positive": "The effect of microscopic scattering on the nonlinear transmission of\n  terahertz fields through monolayer graphene: We consider the nonlinear terahertz response of n-doped monolayer graphene at\nroom temperature using a microscopic theory of carrier dynamics. Our\ntight-binding model treats the carrier-field interaction in the length gauge,\nincludes phonon as well as short-range neutral-impurity scattering, and fully\naccounts for the intrinsic nonlinear response of graphene near the Dirac point.\nTreating each interaction microscopically allows us to separate contributions\nfrom current clipping, phonon creation, and elastic impurity scattering.\nAlthough neutral impurity scattering and phonon scattering are both highly\nenergy-dependent, we find that they impact conduction-band electron dynamics\nvery differently, and that together they can help explain experimental results\nconcerning field-dependent terahertz transmission through graphene."
    },
    {
        "anchor": "Polarization-resolving graphene-based mid-infrared detector: The ability to resolve the polarization of light with on-chip devices\nrepresents an urgent problem in optoelectronics. The detectors with\npolarization resolution demonstrated so far mostly require multiple oriented\ndetectors or movable external polarizers. Here, we experimentally demonstrate\nthe feasibility to resolve the polarization of mid-infrared light with a single\nchemical-vapor-deposited graphene-channel device with dissimilar metal\ncontacts. This possibility stems from an unusual dependence of photoresponse at\ngraphene-metal junctions on gate voltage and polarization angle. Namely, there\nexist certain gate voltages providing the polarization-insensitive signal;\noperation at these voltages can be used for power calibration of the detector.\nAt other gate voltages, the detector features very strong polarization\nsensitivity, with the ratio of signals for two orthogonal polarizations\nreaching ~10. Operation at these voltages can provide information about\npolarization angles, after the power calibration. We show that such unusual\ngate- and polarization-dependence of photosignal can appear upon competition of\nisotropic and anisotropic photovoltage generation pathways and discuss the\npossible physical candidates.",
        "positive": "Tunable resonances due to vacancies in graphene nanoribbons: The coherent electron transport along zigzag and metallic armchair graphene\nnanoribbons in the presence of one or two vacancies is investigated. Having in\nmind atomic scale tunability of the conductance fingerprints, the primary focus\nis on the effect of the distance to the edges and inter vacancies spacing. An\ninvolved interplay of vacancies sublattice location and nanoribbon edge\ntermination, together with the spacing parameters lead to a wide conductance\nresonance line shape modification. Turning on a magnetic field introduces a new\nlength scale that unveils counter-intuitive aspects of the interplay between\npurely geometric aspects of the system and the underlying atomic scale nature\nof graphene."
    },
    {
        "anchor": "Dynamics of van der Waals Charge Qubit in 2D Bilayers: Ab initio Quantum\n  Transport and Qubit Measurement: A van der Waals (vdW) charge qubit, electrostatically confined within\ntwo-dimensional (2D) vdW materials, is proposed as building block of future\nquantum computers. Its characteristics are systematically evaluated with\nrespect to its two-level anti-crossing energy difference ($\\Delta$). Bilayer\ngraphene ($\\Delta$ $\\approx$ 0) and a vdW heterostructure ($\\Delta$ $\\gg$ 0)\nare used as representative examples. Their tunable electronic properties with\nan external electric field define the state of the charge qubit. By combining\ndensity functional theory and quantum transport calculations, we highlight the\noptimal qubit operation conditions based on charge stability and energy-level\ndiagrams. Moreover, a single-electron transistor (SET) design based on trilayer\nvdW heterostructures capacitively coupled to the charge qubit is introduced as\nmeasurement setup with low decoherence and improved measurement properties. It\nis found that a $\\Delta$ greater than 20 meV results in a rapid mixing of the\nqubit states, which leads to a lower measurement quantity, i.e. contrast and\nconductance. With properly optimized designs, qubit architectures relying on 2D\nvdW structures could be integrated into an all-electronic quantum computing\nplatform.",
        "positive": "Adiabatic two-qubit gates in capacitively coupled quantum dot hybrid\n  qubits: The ability to tune qubits to flat points in their energy dispersions (\"sweet\nspots\") is an important tool for mitigating the effects of charge noise and\ndephasing in solid-state devices. However, the number of derivatives that must\nbe simultaneously set to zero grows exponentially with the number of coupled\nqubits, making the task untenable for as few as two qubits. This is a\nparticular problem for adiabatic gates, due to their slower speeds. Here, we\npropose an adiabatic two-qubit gate for quantum dot hybrid qubits, based on the\ntunable, electrostatic coupling between distinct charge configurations. We\nconfirm the absence of a conventional sweet spot, but show that controlled-Z\n(CZ) gates can nonetheless be optimized to have fidelities of $\\sim$99% for a\ntypical level of quasistatic charge noise ($\\sigma_\\varepsilon$$\\simeq$1\n$\\mu$eV). We then develop the concept of a dynamical sweet spot (DSS), for\nwhich the time-averaged energy derivatives are set to zero, and identify a\nsimple pulse sequence that achieves an approximate DSS for a CZ gate, with a\n5$\\times$ improvement in the fidelity. We observe that the results depend on\nthe number of tunable parameters in the pulse sequence, and speculate that a\nmore elaborate sequence could potentially attain a true DSS."
    },
    {
        "anchor": "All-optical Hall effect by the dynamic toroidal moment in a cavity-based\n  metamaterial: Dynamic dipolar toroidal response is demonstrated by an optical plasmonic\nmetamaterial composed of double disks. This response with a hotspot of\nlocalized E-field concentration is a well-behaved toroidal cavity mode that\nexhibits a large Purcell factor due to its deep-subwavelength mode volume.\nAll-optical Hall effect (photovoltaic) due to this optical toroidal moment is\ndemonstrated numerically, in mimicking the magnetoelectric effect in\nmultiferroic systems. The result shows a promising avenue to explore various\noptical phenomena associated with this intriguing dynamic toroidal moment.",
        "positive": "Edge capacitance of a 2D topological insulator: We study capacitance of the 2D topological insulator (TI) edge states. The\ntotal capacitance is combined as a serial circuite of 3 capacitors presenting\ngeometrical $C_G$, quantum $C_Q$ and correlation $C_{corr}$ contributions to\nthe electron energy. If the Coulomb interaction is weak, they obey an\ninequality $C_G<C_Q<C_{corr}$. Quantities $C_G$ and $C_Q$ are found in the case\nof a round TI dot. The quantum capacitance at the finite temperature is\ndetermined taking into account the edge states quantization with and without\nthe magnetic field. We have concluded that, in the accepted approximations,\n$C_{corr}=0$."
    },
    {
        "anchor": "Casimir rack and pinion: Mechanical rectification of periodic\n  multi-harmonic signals: We study noncontact rack and pinion composed of a corrugated plate and a\ncorrugated cylinder intermeshed via the lateral Casimir force. We assume that\nthe rack position versus time is a periodic multi-harmonic signal. We show that\nin a large domain of parameter space and at room temperature, the device acts\nas a mechanical rectifier: The pinion rotates with a nonzero average velocity\nand lifts up an external load. The thermal noise may even facilitate the device\noperation.",
        "positive": "Edge states in a two-dimensional honeycomb lattice of massive magnetic\n  skyrmions: We study the collective dynamics of a two-dimensional honeycomb lattice of\nmagnetic skyrmions. By performing large-scale micromagnetic simulations, we\nfind multiple chiral and non-chiral edge modes of skyrmion oscillations in the\nlattice. The non-chiral edge states are due to the Tamm-Shockley mechanism,\nwhile the chiral ones are topologically protected against structure defects and\nhold different handednesses depending on the mode frequency. To interpret the\nemerging multiband nature of the chiral edge states, we generalize the massless\nThiele's equation by including a second-order inertial term of skyrmion mass as\nwell as a third-order non-Newtonian gyroscopic term, which allows us to model\nthe band structure of skrymion oscillations. Theoretical results compare well\nwith numerical simulations. Our findings uncover the importance of high order\neffects in strongly coupled skyrmions and are helpful for designing novel\ntopological devices."
    },
    {
        "anchor": "Edge States of Monolayer and Bilayer Graphene Nanoribbons: On the basis of tight-binding lattice model, the edge states of monolayer and\nbilayer graphene nanoribbons (GNRs) with different edge terminations are\nstudied. The effects of edge-hopping modulation, spin-orbital coupling (SOC),\nand bias voltage on bilayer GNRs are discussed. We observe the following: (i)\nSome new extra edge states can be created by edge-hopping modulation for\nmonolayer GNRs. (ii) Intralayer Rashba SOC plays a role in depressing the band\nenergy gap $E_g$ opened by intrinsic SOC for both monolayer and bilayer GNRs.\nAn almost linear dependent relation, i.e., $E_g\\sim \\lambda_R$, is found. (iii)\nAlthough the bias voltage favors a bulk energy gap for bilayer graphene without\nintrinsic SOC, it tends to reduce the gap induced by intrinsic SOC. (iv) The\ntopological phase of the quantum spin Hall effect can be destroyed completely\nby interlayer Rashba SOC for bilayer GNRs.",
        "positive": "Tunneling between Two Quantum Hall Droplets: We report on tunneling experiment between two quantum Hall droplets separated\nby a nearly ideal tunnel barrier. The device is produced by cleaved edge\novergrowth that laterally juxtaposes two two-dimensional electron systems\nacross a high quality semiconductor barrier. The dramatic evolution of the\ntunneling characteristics is consistent with the magnetic field-dependent\ntunneling between the coupled edge states of the quantum Hall droplets. We\nidentify a series of quantum critical points between successive strong and weak\ntunneling regimes that are reminiscent of the plateau-transitions in quantum\nHall effect. Scaling analysis shows that the conductance near the critical\nmagnetic fields $B_{c}$ is a function of a single scaling argument\n$|B-B_{c}|T^{-\\kappa}$, where the exponent $\\kappa = 0.42$. This puzzling\nresemblance to a quantum Hall-insulator transition points to the significance\nof interedge correlation in the lateral tunneling of quantum Hall droplets."
    },
    {
        "anchor": "Non-renewal statistics in quantum transport through the eyes of\n  first-passage and waiting time distributions: The waiting time distribution has, in recent years, proven to be a useful\nstatistical tool for characterising transport in nanoscale quantum transport.\nIn particular, as opposed to moments of the distribution of transferred charge,\nwhich have historically been calculated in the long-time limit, waiting times\nare able to detect non-renewal behaviour in mesoscopic systems. They have\nfailed, however, to correctly incorporate backtunneling events. Recently, a\nmethod has been developed that can describe unidirectional and bidirectional\ntransport on an equal footing: the distribution of first-passage times. Rather\nthan the time between successive electron tunnelings, the first-passage refers\nto the first time the number of extra electrons in the drain reaches $+1$.\nHere, we demonstrate the differences between first-passage time statistics and\nwaiting time statistics in transport scenarios where the waiting time either\ncannot correctly reproduce the higher order current cumulants or cannot be\ncalculated at all. To this end, we examine electron transport through a\nmolecule coupled to two macroscopic metal electrodes. We model the molecule\nwith strong electron-electron and electron-phonon interactions in three\nregimes: (i) sequential tunneling and cotunneling for a finite bias voltage\nthrough the Anderson model, (ii) sequential tunneling with no temperature\ngradient and a bias voltage through the Holstein model, and (iii) sequential\ntunneling at zero bias voltage and a temperature gradient through the Holstein\nmodel. We show that, for each transport scenario, backtunneling events play a\nsignificant role; consequently, the waiting time statistics do not correctly\npredict the renewal and non-renewal behaviour, whereas the first-passage time\ndistribution does.",
        "positive": "Exact coherent states of a noninteracting Fermi gas in a harmonic trap: Exact and closed-form expressions of the particle density, the kinetic energy\ndensity, the probability current density, and the momentum distribution are\nderived for a coherent state of a noninteracting Fermi gas, while such a state\ncan be obtained from the ground state in a $d$-dimensional isotropic harmonic\ntrap by modulating the trap frequency and shifting the trap center.\nConservation laws for the relations of the densities are also given. The\nprofile of the momentum distribution turns out to be identical in shape with\nthat of the particle density, however, %as an observable manifestation of the\nuncertainty principle, the dispersion of the distribution increases (decreases)\nwhen that of the particle density is decreased (increased). The expressions are\nalso applicable for a sudden and total opening of the trap, and it is shown\nthat, after the opening, the gas has a stationary momentum distribution whose\ndispersion could be arbitrarily large or small."
    },
    {
        "anchor": "A semi-analytical approach to calculating the dynamic modes of magnetic\n  vortices with Dzyaloshinskii-Moriya interactions: Here we introduce a Landau-Lifshitz based diagonalization (LLD) method, and\nuse this approach to calculate the effects of the interfacial Dzyaloshinskii\nMoriya interactions (DMI) on the radial-type spin wave modes of magnetic\nvortices in circular disks. The LLD method is a semi-analytical approach that\ninvolves the diagonalization of the magnetostatic kernel, exchange, and DMI\ncontributions to extract the system eigenfrequencies and eigenmodes. The\nmagnetic vortex state provides a convenient model system in which to\ninvestigate the effects of the DMI on the dynamics of a magnetic structures\nwith confined geometries. Our calculations show that the DMI leads to shifts of\nthe mode frequencies that are similar in magnitude to what is observed for spin\nwaves of a comparable wavelength in extended films. However, unlike what is\nfound in thin films, only the down-shifted modes are observed in the disks, and\nthese corresponds to modes that propagate either radially outward or inward,\ndepending on the vortex circulation. The semi-analytical calculations agree\nwell with full micromagnetic simulations. This technique also applies to other\nsystems with cylindrical symmetry, for example, magnetic skyrmions.",
        "positive": "Free coherent evolution of a coupled atomic spin system initialized by\n  electron scattering: Full insight into the dynamics of a coupled quantum system depends on the\nability to follow the effect of a local excitation in real-time. Here, we trace\nthe coherent evolution of a pair of coupled atomic spins by means of scanning\ntunneling microscopy. We use a pump-probe scheme to detect the local\nmagnetization following a current-induced excitation performed on one of the\nspins. Making use of magnetic interaction with the probe tip, we are able to\ntune the relative precession of the spins. We show that only if their Larmor\nfrequencies match, the two spins can entangle, causing the excitation to be\nswapped back and forth. These results provide insight into the locality of\nelectron-spin scattering, and set the stage for controlled migration of a\nquantum state through an extended spin lattice."
    },
    {
        "anchor": "Simultaneous imaging of voltage and current density of flowing electrons\n  in two dimensions: Electron transport in nanoscale devices can often result in nontrivial\nspatial patterns of voltage and current that reflect a variety of physical\nphenomena, particularly in nonlocal transport regimes. While numerous\ntechniques have been devised to image electron flows, the need remains for a\nnanoscale probe capable of simultaneously imaging current and voltage\ndistributions with high sensitivity and minimal invasiveness, in magnetic\nfield, across a broad range of temperatures, and beneath an insulating surface.\nHere we present such a technique for spatially mapping electron flows based on\na nanotube single-electron transistor, which achieves high sensitivity for both\nvoltage and current imaging. In a series of experiments using high-mobility\ngraphene devices, we demonstrate the ability of our technique to visualize\nlocal aspects of intrinsically nonlocal transport, as in ballistic flows, which\nare not easily resolvable via existing methods. This technique should both aid\nin understanding the physics of two-dimensional electronic devices, as well as\nenable new classes of experiments that image electron flow through buried\nnanostructures in the quantum and interaction-dominated regimes.",
        "positive": "Theory of double Cooper-pair tunneling and light emission mediated by a\n  resonator: Photon emission by tunneling electrons can be encouraged by locating a\nresonator close to the tunnel junction and applying an appropriate\nvoltage-bias. However, studies of normal metals show that the resonator also\naffects how the charges flow, facilitating processes in which correlated\ntunneling of two charges produces one photon. We develop a theory to analyze\nthis kind of behavior in Josephson junctions by deriving an effective\nHamiltonian describing processes where two Cooper-pairs generate a single\nphoton. We determine the conditions under which the transport is dominated by\nincoherent tunneling of two Cooper-pairs, whilst also uncovering a regime of\ncoherent double Cooper-pair tunneling. We show that the system can also display\nan unusual form of photon-blockade and hence could serve as a single-photon\nsource."
    },
    {
        "anchor": "On Fractional Quantum Hall Effect (FQHE): A Chern-Simons and\n  nonequilibrium quantum transport Weyl transform approach: We give a simple macroscopic phase-space explanation of fractional quantum\nHall effect (FQHE), in a fashion reminiscent of the Landau-Ginsburg macroscopic\nsymmetry breaking analyses. This is in contrast to the more complicated\nmicroscopic wavefunction approaches. Here, we employ a nonequilibrium quantum\ntransport in the lattice Weyl transform formalism. This is coupled with the\nMaxwell Chern-Simons gauge theory for defining fractional filling of Landau\nlevels. Flux attachment concept is inherent in fully occupied and as well as in\npartially occupied Landau levels. We derived the k-factor scaling hierarchy in\nChern-Simons gauge theory, as the scaling hierarchy of the magnetic field or\nmagnetic flux in FQHE. This is crucial in our simple explanation of FQHE as a\ntopological invariant in phase space. For the fundamental scaling hierarchy,\nthe integer k must be a prime number, and for fractions both the numerator and\ndenominator of k must also be prime numbers. The assumption in the literature\nthat a hierarchy of denominators of v = 1 k is given by the expression, (2n +\n1), is wrong. Furthermore, even denominators for v cannot belong to fundamental\nscaling hierarchy and is often absent or less resolved in the experiments.",
        "positive": "Time-resolved second-order correlations of microcavity photons: The time dependence of the correlations between the photons, emitted from the\nmicrocavity with embedded quantum dot under incoherent pumping, is studied\ntheoretically. Analytical expressions for the second-order correlation function\ng2(t) are presented in strong and weak coupling regimes. At moderate pumping\nthe correlation function demonstrates Rabi oscillations, while at larger\npumping it shows monoexponential decay. The decay time of the correlations\nnonmonotonously depends on the pumping value and has a maximum corresponding to\nthe self-quenching transition."
    },
    {
        "anchor": "Realization of magnetic monopoles current in an artificial spin ice\n  device: A step towards magnetronics: Magnetricity- the magnetic equivalent of electricity- was recently verified\nexperimentally for the first time. Indeed, just as the stream of electric\ncharges produces electric current, emergent magnetic monopoles have been\nobserved to roam freely (generating magnetic current) in geometrically\nfrustrated magnets known as spin ice. However, this is realized only by\nconsidering extreme physical conditions as a single crystal of spin ice has to\nbe cooled to a temperature of $0.36 K$. Candidates to overcome this difficulty\nare artificial analogues of spin ice crystals, the so-called artificial spin\nices. Here we show that, by tuning geometrical frustration down, a peculiar\ntype of these artificial systems is an excellent candidate. We produce this\nmaterial and experimentally observe the emergent monopoles; then, we calculate\nthe effects of external magnetic fields, illustrating how to generate\ncontrolled magnetic currents. This potential nano-device for use in\nmagnetronics can be practical even at room temperature and the relevant\nparameters (such as magnetic charge strength etc) for developing this\ntechnology can be tuned at will.",
        "positive": "Dielectric properties of graphene on transition metal dichalcogenide\n  substrate: The tunability of the dielectric properties induced by the substrate driven\ninteractions (SDI) and the exchange field (M) due to the ferro-magnetic\nimpurities in graphene monolayer on transition metal dichalcogenide (TMDC)\n(viz., XY2 , X = Mo, W; Y = S, Se) around K and K prime points is reported\nhere. The cavalcade of interactions involve sub-lattice-resolved, strongly\nenhanced intrinsic spin-orbit couplings(SOC), the extrinsic Rashba spin-orbit\ncoupling (RSOC), and the orbital gap related to the transfer of the electronic\ncharge from graphene to XY2. The RSOC allows for external tuning of the band\ngap in graphene and connects the nearest neighbors with spin-flip. We obtain\nthe usual gapped bands with an effective, RSOC-dependent Zeeman field due to\nthe interplay of SDI. Using these bands we obtain the closed analytical\nexpression of the dielectric function in the finite doping case. The zero of\nthe dielectric function corresponds to the collective mode. Upon including the\nfull dispersion of graphene on TMDC, we find that there is in fact only one\ncollective mode and it corresponds to charge plasmons. The dispersion of the\nlatter yields the q^2/3 behavior and not the well known q^1/2 behavior. We also\nfind that the plasmon frequency could be changed by the tuning of the chemical\npotential."
    },
    {
        "anchor": "The hole Fermi surface in Bi$_{2}$Se$_{3}$ probed by quantum\n  oscillations: Transport and torque magnetometry measurements are performed at high magnetic\nfields and low temperatures in a series of p-type (Ca-doped) Bi$_{2}$Se$_{3}$\ncrystals. The angular dependence of the Shubnikov-de Haas and de Haas-van\nAlphen quantum oscillations enables us to determine the Fermi surface of the\nbulk valence band states as a function of the carrier density. At low density,\nthe angular dependence exhibits a downturn in the oscillations frequency\nbetween $0^\\circ$ and $90^\\circ$, reflecting a bag-shaped hole Fermi surface.\nThe detection of a single frequency for all tilt angles rules out the existence\nof a Fermi surface with different extremal cross-sections down to $24$~meV.\nThere is therefore no signature of a camel-back in the valence band of our bulk\nsamples, in accordance with the direct band gap predicted by $GW$ calculations.",
        "positive": "24 \\textmu m length spin relaxation length in boron nitride encapsulated\n  bilayer graphene: We have performed spin and charge transport measurements in dual gated high\nmobility bilayer graphene encapsulated in hexagonal boron nitride. Our results\nshow spin relaxation lengths $\\lambda_s$ up to 13~\\textmu m at room temperature\nwith relaxation times $\\tau_s$ of 2.5~ns. At 4~K, the diffusion coefficient\nrises up to 0.52~m$^2$/s, a value 5 times higher than the best achieved for\ngraphene spin valves up to date. As a consequence, $\\lambda_s$ rises up to\n24~\\textmu m with $\\tau_s$ as high as 2.9~ns. We characterized 3 different\nsamples and observed that the spin relaxation times increase with the device\nlength. We explain our results using a model that accounts for the spin\nrelaxation induced by the non-encapsulated outer regions."
    },
    {
        "anchor": "Search for Multiple Step Integer Quantum Hall Transitions: Recent experiments in the integer quantum Hall regime seem to find direct\ntransitions from a quantum Hall state with Hall conductance $\\sigma_{xy} = n\ne^2/h $ with integer $n > 1$, to an insulating state in weak magnetic fields.\nWe study this issue using a variation of the tight-binding lattice model for\nnon-interacting electrons. Although quantum Hall transitions with change in\nHall conductance $n e^2/ h$ with $n > 1$ do exist in our model for special\ntuning of parameters, they generically split into quantum Hall transitions with\nthe Hall conductance changing by $e^2 / h$ at each transition. This suggests\nthat a generic multiple step quantum Hall transition is incompatible with a\nnon-interacting electron picture.",
        "positive": "Emergence of a ZO Kohn anomaly in quasi-freestanding epitaxial graphene: In neutral graphene, two prominent cusps known as Kohn anomalies are found in\nthe phonon dispersion of the highest optical phonon at $q=\\Gamma$ (LO branch)\nand $q=K$ (TO branch), reflecting a significant electron-phonon coupling to\nundoped Dirac electrons. In this work, high-resolution electron energy loss\nspectroscopy is used to measure the phonon dispersion around the $\\Gamma$ point\nin quasi-freestanding graphene epitaxially grown on Pt(111). The Kohn anomaly\nfor the LO phonon is observed at finite momentum $q\\sim2k_F$ from $\\Gamma$,\nwith a shape in excellent agreement with the theory and consistent with known\nvalues of the EPC and the Fermi level. More strikingly, we also observe a Kohn\nanomaly at the same momentum for the out-of-plane optical phonon (ZO) branch.\nThis observation is the first direct evidence of the coupling of the ZO mode\nwith Dirac electrons, which is forbidden for freestanding graphene but becomes\nallowed in the presence of a substrate. Moreover, we estimate the EPC to be\neven greater than that of the LO mode, making graphene on Pt(111) an optimal\nsystem to explore the effects of this new coupling in the electronic\nproperties."
    },
    {
        "anchor": "Quantum Interference and Decoherence in Single-Molecule Junctions: How\n  Vibrations Induce Electrical Current: Quantum interference effects and decoherence mechanisms in single-molecule\njunctions are analyzed employing a nonequilibrium Green's function approach.\nElectrons tunneling through quasi-degenerate states of a nanoscale molecular\njunction exhibit interference effects. We show that electronic-vibrational\ncoupling, inherent to any molecular junction, strongly quenches such\ninterference effects. As a result, the electrical current can be significantly\nlarger than without electronic-vibrational coupling. The analysis reveals that\nthe quenching of quantum interference is particularly pronounced if the\njunction is vibrationally highly excited, e.g. due to current-induced\nnonequilibrium effects in the resonant transport regime.",
        "positive": "Band geometry from position-momentum duality at topological band\n  crossings: We show that the position-momentum duality offers a transparent\ninterpretation of the band geometry at the topological band crossings. Under\nthis duality, the band geometry with Berry connection is dual to the\nfree-electron motion under gauge field. This identifies the trace of quantum\nmetric as the dual energy in momentum space. The band crossings with Berry\ndefects thus induce the dual energy quantization in the trace of quantum\nmetric. For the $\\mathbb Z$ nodal-point and nodal-surface semimetals in three\ndimensions, the dual Landau level quantization occurs owing to the Berry\ncharges. Meanwhile, the two-dimensional (2D) Dirac points exhibit the Berry\nvortices, leading to the quantized dual axial rotational energies. Such a\nquantization naturally generalizes to the three-dimensional (3D) nodal-loop\nsemimetals, where the nodal loops host the Berry vortex lines. The $\\mathbb\nZ_2$ monopoles bring about additional dual axial rotational energies, which\noriginate from the links with additional nodal lines. Nontrivial band geometry\ngenerically induces finite spread in the Wannier functions. While the spread\nmanifest quantized lower bounds from the Berry charges, logarithmic divergences\noccur from the Berry vortices. The band geometry at the band crossings may be\nprobed experimentally by a periodic-drive measurement."
    },
    {
        "anchor": "Anomalous thermodynamics of Coulomb interacting massless Dirac fermions\n  in two spatial dimensions: It is argued that the specific heat of $N$ massless Dirac fermions in 2\nspatial dimensions interacting with 1/r Coulomb interactions is suppressed\nlogarithmically relative to its non-interacting counterpart. The\n(dimensionless) coefficient of the logarithm is calculated analytically in the\nleading order in large $N$ expansion, but to all orders in $e^2N$, a procedure\nwhich takes into account finite temperature screening. Experimental observation\nof this effect is expected to occur in a single layer graphene embedded in a\ndielectric medium. Its dependence on the dielectric constant is calculated\nanalytically.",
        "positive": "Scaling Behaviour of Low-Temperature Orthorhombic Domains in\n  Prototypical High-Temperature Superconductor\n  La$_{1.875}$Ba$_{0.125}$CuO$_{4}$: Translational/rotational symmetry breaking and recovery in condensed matter\nsystems are closely related to exotic physical properties such as\nsuperconductivity (SC), magnetism, spin density waves (SDW) and charge density\nwaves (CDW). The interplay between different order parameters is intricate and\noften subject to intense debate, as in the case of CDW order and\nsuperconductivity. In La1:875Ba0:125CuO4 (LBCO), the locations of CDW domains\nare found to be pinned on the nanometer size scale. Coherent X-ray diffraction\ntechniques open routes to directly visualize the domain structures associated\nwith these symmetry changes. We have pushed Bragg Coherent Diffractive Imaging\n(BCDI) into the cryogenic regime where most phase transitions in quantum\nmaterials reside. Utilizing BCDI, we image the structural evolution of LBCO\nmicrocrystal samples during the high-temperature-tetragonal (HTT) to\nlow-temperature-orthorhombic (LTO) phase transition. Our results show the\nformation of LTO domains close to the transition temperature and how the domain\nsize varies with temperature. The LTO domain size is shown to decrease with\ntemperature and to be inversely proportional to the magnitude of the\northorhombic distortion. The number of domains follows the secondary order\nparameter (or orthorhombic strain) measurement with a critical exponent that is\nconsistent with the 3D universality class."
    },
    {
        "anchor": "Strain in Semiconductor Core-Shell Nanowires: We compute strain distributions in core-shell nanowires of zinc blende\nstructure. We use both continuum elasticity theory and an atomistic model, and\nconsider both finite and infinite wires. The atomistic valence force-field\n(VFF) model has only few assumptions. But it is less computationally efficient\nthan the finite-element (FEM) continuum elasticity model. The generic\nproperties of the strain distributions in core-shell nanowires obtained based\non the two models agree well. This agreement indicates that although the\ncalculations based on the VFF model are computationally feasible in many cases,\nthe continuum elasticity theory suffices to describe the strain distributions\nin large core-shell nanowire structures. We find that the obtained strain\ndistributions for infinite wires are excellent approximations to the strain\ndistributions in finite wires, except in the regions close to the ends. Thus,\nour most computationally efficient model, the finite-element continuum\nelasticity model developed for infinite wires, is sufficient, unless edge\neffects are important. We give a comprehensive discussion of strain profiles.\nWe find that the hydrostatic strain in the core is dominated by the axial\nstrain-component, $\\varepsilon_{\\z \\z}$. We also find that although the\nindividual strain components have a complex structure, the hydrostatic strain\nshows a much simpler structure. All in-plane strain components are of similar\nmagnitude. The non-planar off-diagonal strain-components ($\\varepsilon_{\\x \\z}$\nand $\\varepsilon_{\\y \\z}$) are small but nonvanishing. Thus the material is not\nonly stretched and compressed but also warped. The models used can be extended\nfor study of wurtzite nanowire structures, as well as nanowires with multiple\nshells.",
        "positive": "Relativistic non-Fermi liquid from interacting birefringent fermions: A\n  robust superuniversality: We address the emergent quantum critical phenomena for (pseudo)spin-3/2\nbirefringent fermions, featuring two effective Fermi velocities, when they\nreside close to itinerant Mott transitions realized through spontaneous\nsymmetry breaking and triggered by strong local or Hubbardlike repulsive\ninteractions. Irrespective of the nature of the mass orderings that produce\nfully gapped quasiparticle spectra in the ordered phase, which otherwise can be\ngrouped into three classes, the system always possesses a \\emph{unique}\nterminal velocity near the corresponding quantum critical point. The associated\ncritical regime accommodates a relativistic non-Fermi liquid of strongly\ncoupled collective bosonic and spin-1/2 Dirac excitations with vanishing weight\nof the quasiparticle pole. These conclusions are also operative near\nsuperconducting critical points. Therefore, relativistic non-Fermi liquid\npossibly constitutes a robust superuniversal description for the entire family\nof strongly correlated arbitrary half-integer spin Dirac materials."
    },
    {
        "anchor": "Scaled variational computation of the energy spectrum of a\n  two-dimensional hydrogenic donor in a magnetic field of arbitrary strength: We compute the energy levels of a 2D Hydrogen atom when a constant magnetic\nfield is applied. With the help of a mixed-basis variational method and a\ngenera lization of virial theorem, which consists in scaling the wave function,\nwe calculate the binding energies of the 1S, $2P^-$ and $3D^-$ levels. We\ncompare the computed energy spectra with those obtained via a generalization of\nthe mesh point technique as well as the shifted 1/N method. We show that the\nvariational solutions present a very good behavior in the weak and strong\nmagnetic field regimes.",
        "positive": "Excitation and detection of short-waved spin waves in ultrathin\n  Ta/CoFeB/MgO-layer system suitable for spin-orbit-torque magnonics: We report on the excitation and detection of short-waved spin waves with wave\nvectors up to about $40\\,\\mathrm{rad}\\,\\mu\\mathrm{m}^{-1}$ in spin-wave\nwaveguides made from ultrathin, in-plane magnetized Co$_{8}$Fe$_{72}$B$_{20}$\n(CoFeB). The CoFeB is incorporated in a layer stack of Ta/CoFeB/Mgo, a layer\nsystem featuring large spin orbit torques and a large perpendicular magnetic\nanisotropy constant. The short-waved spin waves are excited by nanometric\ncoplanar waveguides and are detected via spin rectification and microfocussed\nBrillouin light scattering spectroscopy. We show that the large perpendicular\nmagnetic anisotropy benefits the spin-wave lifetime greatly, resulting in a\nlifetime comparable to bulk systems without interfacial damping. The presented\nresults pave the way for the successful extension of magnonics to ultrathin\nasymmetric layer stacks featuring large spin orbit torques."
    },
    {
        "anchor": "Organic photovoltaic bulk heterojunctions with spatially varying\n  composition: Models of organic bulk heterojunction photovoltaics which include the effect\nof spatially varying composition of donor/acceptor materials are developed and\nanalyzed. Analytic expressions for the current-voltage relation in simplified\ncases show that the effect of varying blend composition on charge transport is\nminimal. Numerical results for various blend compositions, including the\nexperimentally relevant composition of a donor-rich region near the cathode (a\n\"skin layer\" of donor material), show that the primary effect of this variation\non device performance derives from its effect on photocharge generation. The\ngeneral relation between the geometry of the blend and its effect on\nperformance is given explicitly. The analysis shows that the effect of a skin\nlayer on device performance is small.",
        "positive": "Transmission Properties of Branched Atomic Wires: The renormalization-decimation method is used to study the transmittivity of\natomic wires, with one or more side branches attached at multiple sites. The\nrescaling process reduces all the branches, attached at an atomic site, to an\nequivalent impurity, from which the transmission probability can be calculated\nusing the Lippmann-Schwinger equation. Numerical results show that the\nsubsequent T(E) curves, where particular attention is paid to the numbers and\nlocations of resonances and anti-resonances, are highly sensitive to the values\nof each system's key parameters. These findings provide insight into the design\nof wires with specific desired properties."
    },
    {
        "anchor": "Dynamical stability of the one-dimensional rigid Brownian rotator: The\n  role of the rotator's spatial size and shape: We investigate dynamical stability of a single propeller-like shaped\nmolecular cogwheel modelled as the fixed-axis rigid rotator. In the realistic\nsituations, rotation of the finite-size cogwheel is subject of the envi-\nronmentally-induced Brownian-motion effect that we describe by utilizing the\nquantum Caldeira-Leggett master equation, in the weak-coupling limit. Assuming\nthe initially narrow (classical-like) standard deviations for the an- gle and\nthe angular momentum of the rotator, we investigate dynamics of the first and\nsecond moments depending on the size, i.e., on the number of blades of both the\nfree rotator as well as of the rotator in the external har- monic field. The\nlarger the standard deviations, the less stable (i.e. less pre- dictable)\nrotation. We detect the absence of the simple and straightforward rules for\nutilizing the rotator's stability. Instead, a number of the size-related\ncriteria appear whose combinations may provide the optimal rules for the ro-\ntator dynamical stability and possibly control. In the realistic situations,\nthe quantum-mechanical corrections, albeit individually small, may effectively\nprove non-negligible, and also revealing subtlety of the transition from the\nquantum to the classical dynamics of the rotator. As to the latter, we detect a\nstrong size-dependence of the transition to the classical dynamics beyond the\nquantum decoherence process.",
        "positive": "Disorder effects in the AHE induced by Berry curvature: We describe the charge transport in ferromagnets with spin orbit coupled\nBloch bands by combining the wave-packet evolution equations with the classical\nBoltzmann equation. This approach can be justified in the limit of smooth\ndisorder potential. Besides the skew scattering contribution, we demonstrate\nhow other effects of disorder appear which are closely linked to the Berry\ncurvature of the Bloch states associated with the wavepacket. We show that,\nalthough being of the same order of magnitude as the clean limit Berry\ncurvature contribution, generally disorder corrections depend differently on\nvarious parameters and can lead to the sign reversal of the Hall current as the\nfunction of the chemical potential in systems with a non-constant Berry\ncurvature in momentum space. Earlier conclusions on the effects of disorder on\nthe anomalous Hall effect depended stricly on the lack of momentum dependence\nof the Berry curvature in the models studied and generalizations of their\nfindings to other systems with more complicated band structures were\nunjustified."
    },
    {
        "anchor": "Anharmonic quantum thermal transport across a van der Waals interface: We investigate the anharmonic phonon scattering across a weakly interacting\ninterface by developing a quantum mechanics-based theory. We find that the\ncontribution from anharmonic three-phonon scatterings to interfacial thermal\nconductance can be cast into Landauer formula with transmission function being\ntemperature-dependent. Surprisingly, in the weak coupling limit, the\ntransmission due to anharmonic phonon scattering is unbounded with increasing\ntemperature, which is physically impossible for two-phonon processes. We\nfurther reveal that the anharmonic contribution in a real heterogeneous\ninterface (e.g., between graphene and monolayer molybdenum disulfide) can\ndominate over the harmonic process even at room temperature, highlighting the\nimportant role of anharmonicity in weakly interacting heterogeneous systems.",
        "positive": "New Generation of Massless Dirac Fermions in Graphene under External\n  Periodic Potentials: We show that new massless Dirac fermions are generated when a slowly varying\nperiodic potential is applied to graphene. These quasiparticles, generated near\nthe supercell Brillouin zone boundaries with anisotropic group velocity, are\ndifferent from the original massless Dirac fermions. The quasiparticle\nwavevector (measured from the new Dirac point), the generalized pseudospin\nvector, and the group velocity are not collinear. We further show that with an\nappropriate periodic potential of triangular symmetry, there exists an energy\nwindow over which the only available states are these quasiparticles, thus,\nproviding a good system to probe experimentally the new massless Dirac\nfermions. The required parameters of external potentials are within the realm\nof laboratory conditions."
    },
    {
        "anchor": "Fingering of Electron Droplets in Nonuniform Magnetic Fields: A semiclassical analysis of a two-dimensional electron droplet in a high,\nnonuniform magnetic field predicts that the droplet will form ``fingered''\npatterns upon increasing the number of electrons. We construct explicit\nexamples of these patterns using methods first developed for the flow of\ntwo-dimensional viscous fluids. We complement our analytical results with Monte\nCarlo simulations of the droplet wavefunction, and find that at the point where\nthe semiclassical analysis predicts a cusp on the interface, the droplet\nfissions--a type of ``quantum breakup'' phenomenon.",
        "positive": "Coherent exciton-exciton interactions and exciton dynamics in a\n  MoSe\\textsubscript{2}/WSe\\textsubscript{2} heterostructure: Coherent coupling between excitons is at the heart of many-body interactions\nwith transition metal dichalcogenide (TMD) heterostructures as an emergent\nplatform for the investigation of these interactions. We employ\nmulti-dimensional coherent spectroscopy on monolayer\nMoSe\\textsubscript{2}/WSe\\textsubscript{2} heterostructures and observe\ncoherent coupling between excitons spatially localized in monolayer MoSe$_2$\nand WSe$_2$. Through many-body spectroscopy, we further observe the absorption\nstate arising from free interlayer electron-hole pairs. This observation yields\na spectroscopic measurement of the interlayer exciton binding energy of about\n250 meV."
    },
    {
        "anchor": "From adiabatic to non-adiabatic pumping in graphene nanoribbons: Non-equilibrium two-parameter pumping transport through graphene ribbons,\nattached to reservoirs is described. A tight-binding model is solved using\nKeldysh formalism, and the crossover between adiabatic and non-adiabatic\nregimes is studied. Pumped dc currents through armchair ribbons show properties\ncommon in two-dimensional systems. The width-dependent dc current in zigzag\nribbons, reveals that edge states akin to those in two-dimensional topological\ninsulators, do not contribute to pumped transport in the adiabatic regime. The\ninterplay between propagating and evanescent modes is discussed.",
        "positive": "Observation of monolayer valence band spin-orbit effect and induced\n  quantum well states (QWS) in MoX2: Transition metal dichalcogenides have attracted much attention recently due\nto their potential applications in spintronics and photonics as a result of the\nindirect to direct band gap transition and the emergence of the spin-valley\ncoupling phenomenon upon moving from the bulk to monolayer limit. Here, we\nreport high-resolution angle-resolved photoemission spectroscopy on MoSe2\n(molybdenum diselenide) single crystals and monolayer films of MoS2 grown on\nHighly Ordered Pyrolytic Graphite substrate. Our experimental results, for the\nfirst time, resolve the two distinct bands at the Brillouin zone corner of the\nbulk MoSe2, and provide evidence for the critically important spin-orbit split\nbands of the monolayer MoS2. Moreover, by depositing potassium on cleaved\nsurfaces of these materials, the process through which quantum well states form\non the surfaces of transition metal dichalcogenides is systematically imaged.\nWe present a theoretical model to account for the observed spin-orbit splitting\nand the rich spectrum of the quantum well states observed in our experiments.\nOur findings taken together provide important insights into future applications\nof transition metal dichalcogenides in nanoelectronics, spintronics, and\nphotonics devices as they critically depend on the spin-orbit physics of these\nmaterials."
    },
    {
        "anchor": "Hyperfine interactions in silicon quantum dots: We present an all-electron calculation of the hyperfine parameters for\nconduction electrons in Si, showing that: (i) all parameters scale linearly\nwith the spin density at a $^{29}$Si site; (ii) the isotropic term is over 30\ntimes larger than the anisotropic part; (iii) conduction electron charge\ndensity at a Si nucleus is consistent with experimental estimates; (iv)\nOverhauser fields in natural Si quantum dots (QDs) are two orders of magnitude\nsmaller than in GaAs QDs. This reinforces the outstanding performance of Si in\nkeeping spin coherence and opens access to reliable quantitative information\naiming at spintronic applications.",
        "positive": "Investigation of the behavior of 5CB in a pore and a nano capsule: We use a method of molecular dynamics to investigate the distribution of\nliquid crystal 5CB molecules in a polymeric matrix. Temperature dependences of\nparameters of an order <P2> are calculated. Calculations have shown that\ndepending on the size of a capsule and on a time the transition temperature\nchanges."
    },
    {
        "anchor": "Single electron control in n-type semiconductor quantum dots using\n  non-Abelian holonomies generated by spin orbit coupling: We propose that n-type semiconductor quantum dots with the Rashba and\nDresselhaus spin orbit interactions may be used for single electron\nmanipulation through adiabatic transformations between degenerate states. All\nthe energy levels are discrete in quantum dots and possess a double degeneracy\ndue to time reversal symmetryin the presence of the Rashba and/or Dresselhaus\nspin orbit coupling terms. We find that the presence of double degeneracy does\nnot necessarily give rise to a finite non-Abelian (matrix) Berry phase. We show\nthat a distorted two-dimensional harmonic potential may give rise to\nnon-Abelian Berry phases. The presence of the non-Abelian Berry phase may be\ntested experimentally by measuring the optical dipole transitions.",
        "positive": "Quantum Hall Stripe States in a Tilted Magnetic Field: A strong anisotropy in the longitudinal resistivity of a 2D electron system\nhas been observed at half-filled high Landau levels. We report on detailed\nHartree-Fock calculations of the unidirectional charge density wave (UCDW)\norientation energy induced by a tilted magnetic field. We find that stripes can\norient both parallel or perpendicular to the in-plane field depending on the\nsample parameters and field strength. The close agreement between complex\nexperimental data on different sample geometries and our theoretical results\nstrongly support the UCDW picture as the origin of the observed anisotropies in\nhigh Landau levels."
    },
    {
        "anchor": "Activating spin-forbidden transitions in molecules by the highly\n  localized plasmonic field: Optical spectroscopy has been the primary tool to study the electronic\nstructure of molecules. However the strict spin selection rule has severely\nlimited its ability to access states of different spin multiplicities. Here we\npropose a new strategy to activate spin-forbidden transitions in molecules by\nintroducing spatially highly inhomogeneous plasmonic field. The giant\nenhancement of the magnetic field strength resulted from the curl of the\ninhomogeneous vector potential makes the transition between states of different\nspin multiplicities naturally feasible. The dramatic effect of the\ninhomogeneity of the plasmonic field on the spin and symmetry selection rules\nis well illustrated by first principles calculations of C60. Remarkably, the\nintensity of singlet-triplet transitions can even be stronger than that of\nsinglet-singlet transitions when the plasmon spatial distribution is comparable\nwith the molecular size. This approach offers a powerful means to completely\nmap out all excited states of molecules and to actively control their\nphotochemical processes. The same concept can also be applied to study nano and\nbiological systems.",
        "positive": "Infrared resonance Raman of bilayer graphene: signatures of massive\n  fermions and band structure on the 2D peak: Few-layer graphene possesses low-energy carriers which behave as massive\nfermions, exhibiting intriguing properties in both transport and light\nscattering experiments. Lowering the excitation energy of resonance Raman\nspectroscopy down to 1.17 eV we target these massive quasiparticles in the\nsplit bands close to the K point. The low excitation energy weakens some of the\nRaman processes which are resonant in the visible, and induces a clearer\nfrequency-separation of the sub-structures of the resonance 2D peak in bi- and\ntrilayer samples. We follow the excitation-energy dependence of the intensity\nof each sub-structure and, comparing experimental measurements on bilayer\ngraphene with ab initio theoretical calculations, we trace back such\nmodifications on the joint effects of probing the electronic dispersion close\nto the band splitting and enhancement of electron-phonon matrix elements."
    },
    {
        "anchor": "Mollow \"quintuplets\" from coherently-excited quantum dots: Charge-neutral excitons in semiconductor quantum dots have a small finite\nenergy separation caused by the anisotropic exchange splitting. Coherent\nexcitation of neutral excitons will generally excite both exciton components,\nunless the excitation is parallel to one of the dipole axes. We present a\npolaron master equation model to describe two-exciton pumping using a coherent\ncontinuous wave pump field in the presence of a realistic anisotropic exchange\nsplitting. We predict a five-peak incoherent spectrum, thus generalizing the\nMollow triplet to become a Mollow quintuplet. We experimentally confirm such\nspectral quintuplets for In(Ga)As quantum dots and obtain very good agreement\nwith theory.",
        "positive": "Absence of magnetic-proximity effect at the interface of Bi$_2$Se$_3$\n  and (Bi,Sb)$_2$Te$_3$ with EuS: We performed x-ray magnetic circular dichroism (XMCD) measurements on\nheterostructures comprising topological insulators (TIs) of the\n(Bi,Sb)$_2$(Se,Te)$_3$ family and the magnetic insulator EuS. XMCD measurements\nallow us to investigate element-selective magnetic proximity effects at the\nvery TI/EuS interface. A systematic analysis reveals that there is neither\nsignificant induced magnetism within the TI nor an enhancement of the Eu\nmagnetic moment at such interface. The induced magnetic moments in Bi, Sb, Te,\nand Se sites are lower than the estimated detection limit of the XMCD\nmeasurements of $\\sim\\!10^{-3}$ $\\mu_\\mathrm{B}$/at."
    },
    {
        "anchor": "Effective mass of composite fermion: a phenomenological fit in with\n  anomalous propagation of surface acoustic wave: We calculate the conductivity associated with the anomalous propagation of a\nsurface acoustic wave above a two-dimensional electron gas at $\\nu=1/2$.\nMurthy-Shankar's middle representation is adopted and a contribution to the\nresponse functions beyond the random phase approximation has been taken into\naccount. We give a phenomenological fit for the effective mass of composite\nfermion in with the experimental data of the anomalous propagation of surface\nacoustic wave at $\\nu=1/2$ and find the phenomenological value of the effective\nmass is several times larger than the theoretical value\n$m_{th}^*=6\\epsilon/e^2l_{1/2}$ derived from the Hartree-Fock approximation. We\ncompare our phenomenologically fitting composite fermion effective mass with\nthose appeared in the measurements of the activation energy and the\nShubnikov-de Haas effect and find that our result is fairly reasonable.",
        "positive": "Magnetic Dirac Fermions and Chern Insulator Supported on Pristine\n  Silicon Surface: Emergence of ferromagnetism in non-magnetic semiconductors is strongly\ndesirable, especially in topological materials thanks to the possibility to\nachieve quantum anomalous Hall effect. Based on first-principles calculations,\nwe propose that for Si thin film grown on metal substrate, the pristine\nSi(111)-root3xroot3 surface with a spontaneous weak reconstruction has a strong\ntendency of ferromagnetism and nontrivial topological properties, characterized\nby spin polarized Dirac-fermion surface states. In contrast to conventional\nroutes relying on introduction of alien charge carriers or specially patterned\nsubstrates, the spontaneous magnetic order and spin-orbit coupling on the\npristine silicon surface together gives rise to quantized anomalous Hall effect\nwith a finite Chern number C=-1. This work suggests exciting opportunities in\nsilicon-based spintronics and quantum computing free from alien dopants or\nproximity effects."
    },
    {
        "anchor": "Spin Polarized Transport in Core Shell Nanowire of Silicon and Germanium: We investigate spin polarized electron transport in ultra-thin\nSi-Core/Ge-Shell and Ge-Core/Si-Shell nanowire system using semi-classical\nMonte Carlo simulation method. Depolarization of electron's spin occurs in\nnanowire mainly due to D'yakonov-Perel dephasing (DP-mechanism) and\nElliott-Yafet dephasing (EY-mechanism). We studied the dependence of spin\ndephasing on ultra-thin silicon core diameter in Si-Core/Ge-Shell nanowire and\ngermanium core diameter in Ge-Core/Si-Shell nanowire. Variation in spin\ndephasing length with varying core diameter ranging from 1 nm to 9 nm indicate\nthat spin dephasing length increases with increase in Si-core diameter in\nSi-Core/Ge-Shell nanowire and spin dephasing length decreases with increase in\nGe-core diameter in Ge-Core/Si-Shell nanowire. We then studied the variation in\nspin dephasing length with varying externally applied transverse electric field\nranging from 20 kV/cm to100 kV/cm. In the electric field dependence study we\nfound that spin dephasing length is weakly dependent upon applied electric\nfield. In the end, we studied the variation in spin dephasing length with\nvarying temperature in the range of 4 K to 377 K. In this simulational study we\nfound that for both Si-Core/Ge-Shell and Ge-Core/Si-Shell nanowire system spin\ndephasing length shows a strong dependence on temperature and spin dephasing\nlength increases with decrease in temperature from room temperature range.",
        "positive": "The Ideal Tensile Strength and Phonon Instability of Borophene: Very recently, two-dimensional(2D) boron sheets (borophene) with rectangular\nstructure has been grown successfully on single crystal Ag(111) substrates.The\nfabricated boroprene is predicted to have unusual mechanical properties. We\nperformed first-principle calculations to investigate the mechanical properties\nof the monolayer borophene, including ideal tensile strength and critical\nstrain. It was found that monolayer borophene can withstand stress up to 20.26\nN/m and 12.98 N/m in a and b directions, respectively.However, its critical\nstrain was found to be small. In a direction, the critical value is only 8%,\nwhich, to the best of our knowledge, is the lowest among all studied 2D\nmaterials.Our numerical results show that the tensile strain applied in b\ndirection enhances the bucking height of borophene resulting in an out-of-plane\nnegative Poisson's ratio, which makes the boron sheet show superior mechanical\nflexibility along b direction.The failure mechanism and phonon instability of\nmonolayer borophene were also explored."
    },
    {
        "anchor": "Simulation of highly idealized, atomic scale MQCA logic circuits: Spintronics logic devices based on majority gates formed by atomic-level\narrangements of spins in the crystal lattice is considered. The dynamics of\nswitching is modeled by time-dependent solution of the density-matrix equation\nwith relaxation. The devices are shown to satisfy requirements for logic.\nSwitching speed and dissipated energy are calculated and compared with\nelectronic transistors. The simulations show that for the highly idealized case\nassumed here, it is possible to trade off size for speed and achieve lower\npower operation than ultimately scaled CMOS devices.",
        "positive": "Observation of three-dimensional Dirac semimetal state in topological\n  insulator Bi2Se3: The three dimensional (3D) topological insulators are predicted to exhibit a\n3D Dirac semimetal state in critical regime of topological to trivial phase\ntransition. Here we demonstrate the first experimental evidence of 3D Dirac\nsemimetal state in topological insulator Bi2Se3 with bulk carrier concentration\nof ~ 10^19 cm^{-3}, using magneto-transport measurements. At low temperatures,\nthe resistivity of our Bi2Se3 crystal exhibits clear Shubnikov-de Haas (SdH)\noscillations above 6T. The analysis of these oscillations through\nLifshitz-Onsanger and Lifshitz-Kosevich theory reveals a non-trivial pi Berry\nphase coming from 3D bands, which is a decisive signature of 3D Dirac semimetal\nstate. The large value of Dingle temperature and natural selenium vacancies in\nour crystal suggest that the observed 3D Dirac semimetal state is an outcome of\nenhanced strain field and weaker effective spin-orbit coupling."
    },
    {
        "anchor": "Static and dynamic properties of crystalline phases of two-dimensional\n  electrons in a strong magnetic field: We study the cohesive energy and elastic properties as well as normal modes\nof the Wigner and bubble crystals of the two-dimensional electron system (2DES)\nin higher Landau levels. Using a simple Hartree-Fock approach, we show that the\nshear moduli ($c_{66}$'s) of these electronic crystals show a non-monotonic\nbehavior as a function of the partial filling factor $\\nu^*$ at any given\nLandau level, with $c_{66}$ increasing for small values of $\\nu^*$, before\nreaching a maximum at some intermediate filling factor $\\nu^*_m$, and\nmonotonically decreasing for $\\nu^*>\\nu^*_m$. We also go beyond previous\ntreatments, and study how the phase diagram and elastic properties of electron\nsolids are changed by the effects of screening by electrons in lower Landau\nlevels, and by a finite thickness of the experimental sample. The implications\nof these results on microwave resonance experiments are briefly discussed.",
        "positive": "Critical current and linewidth reduction in spin-torque nano-oscillators\n  by delayed self-injection: Based on theoretical models, the dynamics of spin-torque nano-oscillators can\nbe substantially modified by re-injecting the emitted signal to the input of\nthe oscillator after some delay. Numerical simulations for vortex magnetic\ntunnel junctions show that with reasonable parameters this approach can\ndecrease critical currents as much as 25 % and linewidths by a factor of 4.\nAnalytical calculations, which agree well with simulations, demonstrate that\nthese results can be generalized to any kind of spin-torque oscillator."
    },
    {
        "anchor": "Dirac loops in trigonally connected 3D lattices: We consider different generalizations of the honeycomb lattice to three\ndimensional structures. We address the family of the hyper-honeycomb lattice,\nwhich is made up of alternating layers of 2D honeycomb nano-ribbons, with each\nlayer rotated by $\\pi/2$ with the layer below. When the orbitals of the lattice\nsites are symmetric with respect to the planes of the trigonal links, these\nstructures can produce a Dirac loop, a closed line of Dirac nodes in momentum\nspace. For orbitals that break that symmetry, such as the carbon $p$-wave\norbitals, hyper-honeycomb lattices do not possess the loop structure. We also\nconsider a new structure, the screw hyper-honeycomb, in which the successive\nlayers of parallel units are rotated by $2\\pi/3$. This structure has a Dirac\nloop if reflection symmetry in the unit cell is imposed, regardless the\nsymmetry of the onsite orbitals. We discuss the implementation of those systems\nin optical lattices.",
        "positive": "Quantum Metric Nonlinear Spin-Orbit Torque Enhanced by Topological Bands: Effects manifesting quantum geometry have been a focus of physics research.\nHere, we reveal that quantum metric plays a crucial role in nonlinear electric\nspin response, leading to a quantum metric spin-orbit torque. We argue that\nenhanced quantum metric can occur at band (anti)crossings, so the nonlinear\ntorque could be amplified in topological metals with nodal features close to\nFermi level. By applying our theory to magnetic Kane-Mele model and monolayer\nCrSBr, which feature nodal lines and Weyl points, we demonstrate that the\nquantum metric torque dominates the response, and its magnitude is\nsignificantly enhanced by topological band structures, which even surpasses the\npreviously reported linear torques and is sufficient to drive magnetic\nswitching by itself."
    },
    {
        "anchor": "Diluted Graphene Antiferromagnet: We study RKKY interactions between local magnetic moments for both doped and\nundoped graphene. We find in both cases that the interactions are primarily\nferromagnetic for moments on the same sublattice, and antiferromagnetic for\nmoments on opposite sublattices. This suggests that at sufficiently low\ntemperatures dilute magnetic moments embedded in graphene can order into a\nstate analogous to that of a dilute antiferromagnet. We find that in the\nundoped case one expects no net magnetic moment, and demonstrate numerically\nthat this effect generalizes to ribbons where the magnetic response is\nstrongest at the edge, suggesting the possibility of an unusual spin-transfer\ndevice. For doped graphene we find that moments at definite lattice sites\ninteract over longer distances than those placed in interstitial sites of the\nlattice ($1/R^2$ vs. $1/R^3$) because the former support a Kohn anomaly that is\nsuppressed in the latter due to the absence of backscattering.",
        "positive": "Giving electrons a ride: nanomechanical electron shuttles: Nanomechanical shuttles transferring small groups of electrons or even\nindividual electrons from one electrode to another offer a novel approach to\nthe problem of controlled charge transport. Here, we report the fabrication of\nshuttle-junctions consisting of a 20 nm diameter gold nanoparticle embedded\nwithin the gap between two gold electrodes. The nanoparticle is attached to the\nelectrodes through a monolayer of flexible organic molecules which play the\nrole of springs so that when a sufficient voltage bias is applied, then\nnanoparticle starts to oscillate transferring electrons from one electrode to\nthe other. Current-voltage characteristics for the fabricated devices have been\nmeasured and compared with the results of our computer simulations."
    },
    {
        "anchor": "Atomic-scale manipulation and in situ characterization with scanning\n  tunneling microscopy: Scanning tunneling microscope (STM) has presented a revolutionary methodology\nto the nanoscience and nanotechnology. It enables imaging the topography of\nsurfaces, mapping the distribution of electronic density of states, and\nmanipulating individual atoms and molecules, all at the atomic resolution. In\nparticular, the atom manipulation capability has evolved from fabricating\nindividual nanostructures towards the scalable production of the atomic-sized\ndevices bottom-up. The combination of precision synthesis and in situ\ncharacterization of the atomically precise structures has enabled direct\nvisualization of many quantum phenomena and fast proof-of-principle testing of\nquantum device functions with real-time feedback to guide the improved\nsynthesis. In this article, several representative examples are reviewed to\ndemonstrate the recent development of atomic scale manipulation. Especially,\nthe review focuses on the progress that address the quantum properties by\ndesign through the precise control of the atomic structures in several\ntechnologically relevant materials systems. Besides conventional STM\nmanipulations and electronic structure characterization with single-probe STM,\nintegration of multiple atomically precisely controlled probes in a multiprobe\nSTM system vastly extends the capability of in situ characterization to a new\ndimension where the charge and spin transport behaviors can be examined from\nmesoscopic to atomic length scale. The automation of the atomic scale\nmanipulation and the integration with the well-established lithographic\nprocesses would further push this bottom-up approach to a new level that\ncombines reproducible fabrication, extraordinary programmability, and the\nability to produce large-scale arrays of quantum structures.",
        "positive": "Electron-vibration interaction in single-molecule junctions: from\n  contact to tunneling regime: Point contact spectroscopy on a H2O molecule bridging Pt electrodes reveals a\nclear crossover between enhancement and reduction of the conductance due to\nelectron-vibration interaction. As single channel models predict such a\ncrossover at transmission probability of t=0.5, we used shot noise measurements\nto analyze the transmission and observed at least two channels across the\njunction where the dominant channel has t=0.51+/-0.01 transmission probability\nat the crossover conductance, which is consistent with the predictions for\nsingle-channel models."
    },
    {
        "anchor": "Relating Andreev Bound States and Supercurrents in Hybrid Josephson\n  Junctions: We investigate superconducting quantum interference devices consisting of two\nhighly transmissive Josephson junctions coupled by a superconducting loop, all\ndefined in an epitaxial InAs/Al heterostructure. A novel device design allows\nfor independent measurements of the Andreev bound state spectrum within the\nnormal region of a junction and the resulting current-phase relation. We show\nthat knowledge of the Andreev bound state spectrum alone is enough to derive\nthe independently measured phase dependent supercurrent. On the other hand, the\nopposite relation does not generally hold true as details of the energy\nspectrum are averaged out in a critical current measurement. Finally,\nquantitative understanding of field dependent spectrum and supercurrent require\ntaking into account the second junction in the loop and the kinetic inductance\nof the epitaxial Al film.",
        "positive": "Toward a global phase diagram of the fractional quantum anomalous Hall\n  effect: Recent experiments on the twisted semiconductor bilayer system $t$MoTe$_2$\nhave observed integer and fractional quantum anomalous Hall effects, which\noccur in topological moir\\'e bands at zero magnetic field. Here, we present a\nglobal phase diagram of $t$MoTe$_2$ throughout the filling range $0< n\\leq 1$\nsubstantiated by exact diagonalization calculations. At a magic angle, we find\nthat the system resembles the lowest Landau level (LLL) to a remarkable degree,\nexhibiting an abundance of incompressible fractional quantum anomalous Hall\nstates and compressible anomalous composite Fermi liquid states. Away from the\nmagic angle, particle-hole symmetry is strongly broken. Some LLL-like features\nremain robust near half-filling, while others are replaced, predominantly by\ncharge density waves near $n=0$ and anomalous Hall Fermi liquids near $n=1$.\nAmong LLL-like phases, we find the anomalous composite Fermi liquid at\n$n=\\frac{1}{2}$ to be most robust against deviations from the magic angle.\nWithin the band-projected model, we show that strong particle-hole asymmetry\nabove the magic angle results from interaction-enhanced quasiparticle\ndispersion near $n=1$. Our work sets the stage for future exploration of\nLLL-like and beyond-LLL phases in fractional quantum anomalous Hall systems."
    },
    {
        "anchor": "Kondo screening cloud in a double-quantum dot system: We analyze the transport properties of two artificial magnetic impurities\ncoupled togethervia a tunable RKKY interaction mediated by conduction electrons\nof a finite size one dimensional wire. We show that the sign of the RKKY\ninteraction can be controlled by gating the wire. We investigate the interplay\nbetween finite size effects and RKKY interaction and found that the two\nartificial impurities start to interact each-other as soon as the Kondo\nscreening cloud length becomes larger that the length of the wire. This should\nallow to give a lower experimental estimate of the Kondo screening cloud\nlength.",
        "positive": "Magnetoplasmon resonance technique to monitor two-dimensional Dirac\n  superconductors in fluctuating regime: We propose the magnetoplasmon resonance technique to investigate\ntwo-dimensional superconductors (taking MoS$_2$ as an example) in the\nfluctuating regime, where the temperature is slightly above the critical\ntemperature of the superconducting transition. Thus, unpaired electrons and\nfluctuating Cooper pairs coexist in the system and interact with each other via\nlong-range Coulomb forces, forming a Bose-Fermi mixture. We expose the sample\nto external time-dependent electromagnetic field with a frequency in\nsub-terahertz range and a permanent magnetic field, and show that the\nmagnetoplasmon response of the system is strongly modified in the presence of\nsuperconducting fluctuations in the vicinity of the superconducting transition.\nIn particular, the fluctuating Cooper pairs dramatically change the position\nand broadening of the magnetoplasmon resonance, which is reflected in the\noptical response of the system."
    },
    {
        "anchor": "Comment on the \"Create Dirac Cones in Your Favorite Materials\", by\n  Chia-Hui Lin and Wei Ku (arXiv:1303.4822): Recently a paper by Lin and Ku \\cite{lin} was posted, where the authors\npropose a very interesting idea to engineer the Dirac points in material which\noriginally did not have such points by inducing a CDW state through\nintroduction of impurities like vacancy, substitution, or intercalation. In\nthis comment we would like to explain the appearance of the Dirac points in\nsuch engineered structures by symmetry arguments.",
        "positive": "Higher-Order Nodal Points in Two Dimensions: A two-dimensional (2D) topological semimetal is characterized by the nodal\npoints in its low-energy band structure. While the linear nodal points have\nbeen extensively studied, especially in the context of graphene, the realm\nbeyond linear nodal points remains largely unexplored. Here, we explore the\npossibility of higher-order nodal points, i.e., points with higher-order energy\ndispersions, in 2D systems. We perform an exhaustive search over all 80 layer\ngroups both with and without spin-orbit coupling (SOC), and reveal all possible\nhigher-order nodal points. We show that they can be classified into two\ncategories: the quadratic nodal point (QNP) and the cubic nodal point (CNP).\nAll the 2D higher-order nodal points have twofold degeneracy, and the order of\ndispersion cannot be higher than three. QNPs only exist in the absence of SOC,\nwhereas CNPs only exist in the presence of SOC. Particularly, the CNPs\nrepresent a new topological state not known before. We show that they feature\nnontrivial topological charges, leading to extensive topological edge bands.\nOur work completely settles the problem of higher-order nodal points, discovers\nnovel topological states in 2D, and provides detailed guidance to realize these\nstates. Possible material candidates and experimental signatures are discussed."
    },
    {
        "anchor": "Spin torque gate magnetic field sensor: Spin-orbit torque provides an efficient pathway to manipulate the magnetic\nstate and magnetization dynamics of magnetic materials, which is crucial for\nenergy-efficient operation of a variety of spintronic devices such as magnetic\nmemory, logic, oscillator, and neuromorphic computing. Here, we describe and\nexperimentally demonstrate a strategy for the realization of a spin torque gate\nmagnetic field sensor with extremely simple structure by exploiting the\nlongitudinal field dependence of the spin torque driven magnetization\nswitching. Unlike most magnetoresistance sensors which require a delicate\nmagnetic bias to achieve a linear response to the external field, the spin\ntorque gate sensor can achieve the same without any magnetic bias, which\ngreatly simplifies the sensor structure. Furthermore, by driving the sensor\nusing an ac current, the dc offset is automatically suppressed, which\neliminates the need for a bridge or compensation circuit. We verify the concept\nusing the newly developed WTe2/Ti/CoFeB trilayer and demonstrate that the\nsensor can work linearly in the range of 3-10 Oe with negligible dc offset.",
        "positive": "Effect of the quantistic zero-point atomic motion on the opto-electronic\n  properties of diamond and trans-polyacetylene: The quantistic zero-point motion of the carbon atoms is shown to induce\nstrong effects on the opto-electronic properties of diamond and\ntrans-polyacetylene, a conjugated polymer. By using an ab initio approach, we\ninterpret the sub-gap states experimentally observed in diamond in terms of\nentangled electron-phonon states. These states also appear in\ntrans-polyacetylene causing the formation of strong structures in the\nband-structure that even call into question the accuracy of the band theory.\nThis imposes a critical revision of the results obtained for carbon-based\nnano-structures by assuming the atoms frozen in their equilibrium positions."
    },
    {
        "anchor": "Landau Level Crossings and Extended-State Mapping in Magnetic\n  Two-dimensional Electron Gases: We present longitudinal and Hall magneto-resistance measurements of a\n``magnetic'' two-dimensional electron gas (2DEG) formed in modulation-doped\nZn$_{1-x-y}$Cd$_{x}$Mn$_{y}$Se quantum wells. The electron spin splitting is\ntemperature and magnetic field dependent, resulting in striking features as\nLandau levels of opposite spin cross near the Fermi level. Magnetization\nmeasurements on the same sample probe the total density of states and Fermi\nenergy, allowing us to fit the transport data using a model involving extended\nstates centered at each Landau level and two-channel conduction for spin-up and\nspin-down electrons. A mapping of the extended states over the whole quantum\nHall effect regime shows no floating of extended states as Landau levels cross\nnear the Fermi level.",
        "positive": "Controlling a Nanowire Spin-Orbit Qubit via Electric-Dipole Spin\n  Resonance: A semiconductor nanowire quantum dot with strong spin-orbit coupling (SOC)\ncan be used to achieve a spin-orbit qubit. In contrast to a spin qubit, the\nspin-orbit qubit can respond to an external ac electric field, an effect called\nelectric-dipole spin resonance. Here we develop a theory that can apply in the\nstrong SOC regime. We find that there is an optimal SOC strength\n\\eta_{opt}=\\sqrt{2}/2, where the Rabi frequency induced by the ac electric\nfield becomes maximal. Also, we show that both the level spacing and the Rabi\nfrequency of the spin-orbit qubit have periodic responses to the direction of\nthe external static magnetic field. These responses can be used to determine\nthe SOC in the nanowire."
    },
    {
        "anchor": "Inelastic electron transport in granular arrays: Transport properties of granular systems are governed by Coulomb blockade\neffects caused by the discreteness of the electron charge. We show that, in the\nlimit of vanishing mean level spacing on the grains, the low-temperature\nbehavior of 1d and 2d arrays is insulating at any inter-grain coupling\n(characterized by a dimensionless conductance g.) In 2d and g>>1, there is a\nsharp Berezinskii-Kosterlitz-Thouless crossover to the conducting phase at a\ncertain temperature, T_{BKT}. These results are obtained by applying an\ninstanton analysis to map the conventional `phase' description of granular\narrays onto the dual `charge' representation.",
        "positive": "Astability versus Bistability in van der Waals Tunnel Diode for Voltage\n  Controlled Oscillator and Memory Applications: Van der Waals (vdW) tunnel junctions are attractive due to their atomically\nsharp interface, gate tunablity, and robustness against lattice mismatch\nbetween the successive layers. However, the negative differential resistance\n(NDR) demonstrated in this class of tunnel diodes often exhibits noisy\nbehaviour with low peak current density, and lacks robustness and\nrepeatability, limiting their practical circuit applications. Here we propose a\nstrategy of using a 1L-WS$_2$ as an optimum tunnel barrier sandwiched in a\nbroken gap tunnel junction of highly doped black phosphorus (BP) and SnSe$_2$.\nWe achieve high yield tunnel diodes exhibiting highly repeatable, ultra-clean,\nand gate tunable NDR characteristics with a signature of intrinsic oscillation,\nand a large peak-to-valley current ratio (PVCR) of 3.6 at 300 K (4.6 at 7 K),\nmaking them suitable for practical applications. We show that the thermodynamic\nstability of the vdW tunnel diode circuit can be tuned from astability to\nbistability by altering the constraint through choosing a voltage or a current\nbias, respectively. In the astable mode under voltage bias, we demonstrate a\ncompact, voltage controlled oscillator without the need for an external tank\ncircuit. In the bistable mode under current bias, we demonstrate a highly\nscalable, single element one-bit memory cell that is promising for dense random\naccess memory applications in memory intensive computation architectures."
    },
    {
        "anchor": "First and second-order metal-insulator phase transitions and topological\n  aspects of a Hubbard-Rashba system: This paper considers a model consisting of a kinetic term, Rashba spin-orbit\ncoupling and short-range Coulomb interaction at zero-temperature. The Coulomb\ninteraction is decoupled by a mean-field approximation in the spin channel\nusing field theory methods. The results feature a first-order phase transition\nfor any finite value of the chemical potential and quantum criticality for\nvanishing chemical potential. The Hall conductivity is also computed using Kubo\nformula in a mean-field effective Hamiltonian. In the limit of infinite mass\nthe kinetic term vanishes and all the phase transitions are of second order, in\nthis case spontaneous symmetry breaking mechanism adds a ferromagnetic metallic\nphase to the system and features a zero-temperature quantization of the Hall\nconductivity in the insulating one.",
        "positive": "Mitigating information leakage in a crowded spectrum of weakly\n  anharmonic qubits: A challenge for scaling up quantum processors using frequency-crowded, weakly\nanharmonic qubits is to drive individual qubits without causing leakage into\nnon-computational levels of the others, while also minimizing the number of\ncontrol lines. To address this, we implement single-qubit Wah-Wah control in a\ncircuit QED processor with a single feedline for all transmon qubits, operating\nat the maximum gate speed achievable given the frequency crowding. Randomized\nbenchmarking and quantum process tomography confirm alternating qubit control\nwith $\\leq$1% average error per computational step and decoherence-limited\nidling of one qubit while driving another with a Wah-Wah pulse train."
    },
    {
        "anchor": "Thermoelectric-induced unitary Cooper pair splitting efficiency: Thermoelectric effect is exploited to optimize the Cooper pair splitting\nefficiency in a Y-shaped junction, which consists of two normal leads coupled\nto an $s$-wave superconductor via double noninteracting quantum dots. Here,\nutilizing temperature difference rather than bias voltage between the two\nnormal leads, and tuning the two dot levels such that the transmittance of\nelastic cotunneling process is particle-hole symmetric, we find currents\nflowing through the normal leads are totally contributed from the splitting of\nCooper pairs emitted from the superconductor. Such a unitary splitting\nefficiency is significantly better than the efficiencies obtained in\nexperiments so far.",
        "positive": "Two-Channel Kondo Effects in Al/AlO$_{x}$/Sc Planar Tunnel Junctions: We have measured the differential conductances $G(V,T)$ in several\nAl/AlO$_{x}$/Sc planar tunnel junctions between 2 and 35 K. As the temperature\ndecreases to $\\sim$ 16 K, the zero-bias conductance $G(0,T)$ crosses over from\na standard $-$ln$T$ dependence to a novel $- \\sqrt{T}$ dependence.\nCorrespondingly, the finite bias conductance $G(V,T)$ reveals a two-channel\nKondo scaling behavior between $\\sim$ 4 and 16 K. The observed two-channel\nKondo physics is ascribed to originating from a few localized spin-$\\frac12$ Sc\natoms situated slightly inside the AlO$_x$/Sc interface."
    },
    {
        "anchor": "Controlling charge and spin transport in an Ising-superconductor\n  Josephson junction: An in-plane magnetic field applied to an Ising superconductor converts\nspin-singlet Cooper pairs to spin-triplet ones. In this work, we study a\nJosephson junction formed by two Ising superconductors that are proximitized by\nferromagnetic layers. This leads to highly tunable spin-triplet pairing\ncorrelations which allow to modulate the charge and spin supercurrents through\nthe in-plane magnetic exchange fields. For a junction with a nonmagnetic\nbarrier, the charge current is switchable by changing the relative alignment of\nthe in-plane exchange fields, and a $\\pi$-state can be realized. Furthermore,\nthe charge and spin current-phase relations display a $\\phi_0$-junction\nbehavior for a strongly spin-polarized ferromagnetic barrier.",
        "positive": "Flux periodic oscillations and phase-coherent transport in GeTe\n  nanowire-based devices: Despite the fact that GeTe is known to be a very interesting material for\napplications in thermoelectrics and for phase-change memories, the knowledge on\nits low-temperature transport properties is only limited. Here, we report on\nphase-coherent phenomena in the magnetotransport of GeTe nanowires. From\nuniversal conductance fluctuations, a phase-coherence length of about 200nm at\n0.5K is determined for the hole carriers. The distinct phase-coherence is\nconfirmed by the observation of Aharonov--Bohm type oscillations for magnetic\nfields applied along the nanowire axis. We interpret the occurrence of these\nmagnetic flux-periodic oscillations by the formation of a tubular hole\naccumulation layer on the nanowire surface. In addition, for\nNb/GeTe-nanowire/Nb Josephson junctions, we obtained a proximity-induced\ncritical current of about 0.2$\\mu$A at 0.4K. By applying a magnetic field\nperpendicular to the nanowire axis, the critical current decreases monotonously\nwith increasing magnetic field, which indicates that the structure is in the\nsmall-junction-limit. Whereas, by applying a parallel magnetic field the\ncritical current oscillates with a period of the magnetic flux quantum\nindicating once again the presence of a tubular hole channel."
    },
    {
        "anchor": "Disentangled higher-orbital bands and chiral symmetric topology in\n  confined Mie resonance photonic crystals: Topological phases based on tight-binding models have been extensively\nstudied in recent decades. By mimicking the linear combination of atomic\norbitals in tight-binding models based on the evanescent couplings between\nresonators in classical waves, numerous experimental demonstrations of\ntopological phases have been successfully conducted. However, in dielectric\nphotonic crystals, the Mie resonances' states decay too slowly as $1/r$ when\n$r$ $\\to$ $\\infty$, leading to intrinsically different physical properties\nbetween tight-binding models and dielectric photonic crystals. Here, we propose\na confined Mie resonance photonic crystal by embedding perfect electric\nconductors in between dielectric rods, leading to a perfectly matched band\nstructure as the tight-binding models with nearest-neighbour couplings. As a\nconsequence, disentangled band structure spanned by higher atomic orbitals is\nobserved. Moreover, we also achieve a three-dimensional photonic crystal with a\ncomplete photonic bandgap and third-order topology based on our design. Our\nimplementation provides a versatile platform for studying exotic higher-orbital\nbands and achieving tight-binding-like 3D topological photonic crystals.",
        "positive": "Stability of low-friction surface sliding of nanocrystals with\n  rectangular symmetry and application to W on NaF(001): We investigate the stability of low-friction sliding of nanocrystal with\nrectangular atomic arrangement on rectangular lattices, for which analytical\nresults can be obtained. We find that several incommensurate periodic orbits\nexist and are stable against thermal fluctuations and other perturbations. As\nincommensurate orientations lead to low corrugation, and therefore low\nfriction, such incommensurate periodic orbits are interesting for the study of\nnanotribology. The analytical results compare very well with simulations of W\nnanocrystals on NaF(001). The geometry and high typical corrugation of\nsubstrates with square lattices increase the robustness compared to typical\nhexagonal lattices, such as graphite."
    },
    {
        "anchor": "Bell-state tomography in a silicon many-electron artificial molecule: An error-corrected quantum processor will require millions of qubits,\naccentuating the advantage of nanoscale devices with small footprints, such as\nsilicon quantum dots. However, as for every device with nanoscale dimensions,\ndisorder at the atomic level is detrimental to qubit uniformity. Here we\ninvestigate two spin qubits confined in a silicon double-quantum-dot artificial\nmolecule. Each quantum dot has a robust shell structure and, when operated at\nan occupancy of 5 or 13 electrons, has single spin-$\\frac{1}{2}$ valence\nelectron in its $p$- or $d$-orbital, respectively. These higher electron\noccupancies screen atomic-level disorder. The larger multielectron\nwavefunctions also enable significant overlap between neighbouring qubit\nelectrons, while making space for an interstitial exchange-gate electrode. We\nimplement a universal gate set using the magnetic field gradient of a\nmicromagnet for electrically-driven single qubit gates, and a\ngate-voltage-controlled inter-dot barrier to perform two-qubit gates by pulsed\nexchange coupling. We use this gate set to demonstrate a Bell state preparation\nbetween multielectron qubits with fidelity 90.3%, confirmed by two-qubit state\ntomography using spin parity measurements.",
        "positive": "On the effect of linear feedback and parametric pumping on a resonators\n  frequency stability: Resonant sensors based on Micro- and Nano-Electro Mechanical Systems (M/NEMS)\nare ubiquitous in many sensing applications due to their outstanding\nperformance capabilities, which are directly proportional to the quality factor\n(Q) of the devices. We address here a recurrent question in the field: do\ndynamical techniques that modify the effective Q (namely parametric pumping and\ndirect drive velocity feedback) affect the performance of said sensors? We\ndevelop analytical models of both cases, while remaining in the linear regime,\nand introduce noise in the system from two separate sources: thermomechanical\nand amplifier (read-out) noise. We observe that parametric pumping enhances the\nquality factor in the amplitude response, but worsens it in the phase response\non the resonator. In the case of feedback, we find that Q is enhanced in both\ncases. Then, we establish a solution for the noisy problem with direct drive\nand parametric pumping simultaneously. We also find that, in the case when\nthermomechanical noise dominates, no benefit can be obtained from neither\nartificial Q-enhancement technique. However, in the case when amplifier noise\ndominates, we surprisingly observe that a significant advantage can only be\nachieved using parametric pumping in the squeezing region."
    },
    {
        "anchor": "Giant circular dichroism in individual carbon nanotubes induced by\n  extrinsic chirality: Circular dichroism is widely used for characterizing organic and biological\nmaterials, but measurements at a single molecule level are challenging because\ndifferences in absorption for opposite helicities are small. Here we show that\nextrinsic chirality can induce giant circular dichroism in individual carbon\nnanotubes, with degree of polarization reaching 65%. The signal has a large\ndependence on the incidence angle, consistent with the interpretation that\nmirror symmetry breaking by the optical wave vector is responsible for the\neffect. We propose that field-induced charge distribution results in an\nefficient polarization conversion, giving rise to the giant dichroism. Our\nresults highlight the possibility of polarization manipulation at the nanoscale\nfor applications in integrated photonics and novel metamaterial designs.",
        "positive": "Effect of the Equivalence Between Topological and Electric Charge on the\n  Magnetization of the Hall Ferromagnet: The dependence on temperature of the spin magnetization of a two-dimensional\nelectron gas at filling factor unity is studied. Using classical Monte Carlo\nsimulations we analyze the effect that the equivalence between topological and\nelectrical charge has on the the behavior of the magnetization. We find that at\nintermediate temperatures the spin polarization increases in a thirty per cent\ndue to the Hartree interaction between charge fluctuations."
    },
    {
        "anchor": "A consistent interpretation of the low temperature magneto-transport in\n  graphite using the Slonczewski--Weiss--McClure 3D band structure calculations: Magnetotransport of natural graphite and highly oriented pyrolytic graphite\n(HOPG) has been measured at mK temperatures. Quantum oscillations for both\nelectron and hole carriers are observed with orbital angular momentum quantum\nnumber up to $N\\approx90$. A remarkable agreement is obtained when comparing\nthe data and the predictions of the Slonczewski--Weiss--McClure tight binding\nmodel for massive fermions. No evidence for Dirac fermions is observed in the\ntransport data which is dominated by the crossing of the Landau bands at the\nFermi level, corresponding to $dE/dk_z=0$, which occurs away from the $H$ point\nwhere Dirac fermions are expected.",
        "positive": "Electrical reversal of the sign for magnon thermal Hall coefficient in\n  van der Waals bilayer antiferromagnet: With spin-layer locking, the manipulation of spin degree of freedom via\nperpendicular electric field can be realized in a typical antiferromagnetically\ncoupled bilayer. In analogy to the electric control of the anomalous layer Hall\neffect of electron within such bilayer system, we propose here its magnon\ncounterpart i.e., thermal Hall effect controlled by a perpendicular electric\nfield. Unlike electrons, magnon is charged neutral and its transport in solids\ncan be driven by a thermal gradient. It also exhibits Hall response due to the\nintrinsic Berry curvature of magnon, analogous to the achievement in electron\nsystem. Taking bilayer 2H-VSe2 with both H-type stacking interlayer\nantiferromagnetic coupling as a platform, we perform first-principles\ncalculations towards the magnetic exchange coupling parameters under applied\nelectric field perpendicular to the plane. Based on linear spin wave\napproximation, we then fit the magnon band structures accordingly and calculate\nthe corresponding Berry curvature. The thermal Hall coefficient dependence on\nthe temperature under thermal gradient can be calculated correspondingly in\nlinear response regime. It is shown that electric field reversal is able to\nreverse the sign of the coefficient. These findings provide a platform for the\nrealization of all-electric magnon spintronics."
    },
    {
        "anchor": "The tunnel magnetoresistance in chains of quantum dots weakly coupled to\n  external leads: We analyze numerically the spin-dependent transport through coherent chains\nof three coupled quantum dots weakly connected to external magnetic leads. In\nparticular, using the diagrammatic technique on the Keldysh contour, we\ncalculate the conductance, shot noise and tunnel magnetoresistance (TMR) in the\nsequential and cotunneling regimes. We show that transport characteristics\ngreatly depend on the strength of the interdot Coulomb correlations, which\ndetermines the spacial distribution of electron wave function in the chain.\nWhen the correlations are relatively strong, depending on the transport regime,\nwe find both negative TMR as well as TMR enhanced above the Julliere value,\naccompanied with negative differential conductance (NDC) and super-Poissonian\nshot noise. This nontrivial behavior of tunnel magnetoresistance is associated\nwith selection rules that govern tunneling processes and various high-spin\nstates of the chain that are relevant for transport. For weak interdot\ncorrelations, on the other hand, the TMR is always positive and not larger than\nthe Julliere TMR, although super-Poissonian shot noise and NDC can still be\nobserved.",
        "positive": "On ultrafast polarization switching in ferroelectrics: Recently, a method of ultrafast polarization switching in ferroelectrics has\nbeen suggested. The basic idea of the method is to employ the effect of\nself-acceleration of polarization dynamics due to a resonator feedback field.\nThis is the idea of principle whose efficiency is demonstrated by an Ising-type\nmodel in a transverse field. Of course, the practical realization of the method\nrequires the choice of appropriate materials, which is a separate problem. For\nexample, the standard order-disorder ferroelectrics with spatially symmetric\ndouble-well potentials cannot be used for this purpose, since, because of the\nsymmetry, they lack the transverse polarization. However, ferroelectrics with\nasymmetric potentials, possessing this polarization, can be used. Moreover, if\nthe potential asymmetry, hence the transverse polarization, could be regulated,\ne.g., by shear stress or shear strain, this could provide a tool for governing\nthe process of polarization switching."
    },
    {
        "anchor": "Correlation effects in disordered conductors with spin accumulation: We consider the effect of electron-electron interaction on the density of\nstates of disordered paramagnetic conductor in the presence of spin\naccumulation and magnetic field. We show that interaction correction to\nelectron density of states of the paramagnet may exhibit singularities at\nenergies corresponding to the difference between chemical potentials of\nelectrons with opposite spins. We also discuss correlation effects on\nconductivity in metallic as well as in hopping regimes and show that spin\naccumulation leads to the negative magnetoconductivity.",
        "positive": "Intrinsic torques emerging from anomalous velocity in magnetic textures: Momentum-space topology of electrons under strong spin-orbit coupling\ncontributes to the electrically induced torques exerting on magnetic textures\ninsensitively to disorder or thermal fluctuation. We present a direct\nconnection between band topology and the torques by classifying the whole\ntorques phenomenologically. As well as the intrinsic anomalous Hall effect, the\ntorques also emerge intrinsically from the anomalous velocity of electrons\nregardless of a nonequilibrium transport current. We especially point out the\nintrinsic contribution arising exclusively in magnetic textures, which we call\nthe \"topological Hall torque (THT).\" The THT emerges in bulk crystals without\nany interface or surface structures. We numerically demonstrate the enhancement\nof the THT in comparison with the conventional spin-transfer torque in the bulk\nmetallic ferromagnet, which accounts for the giant current-induced torque\nmeasured in ferromagnetic SrRuO3."
    },
    {
        "anchor": "Berry connection polarizability tensor and third-order Hall effect: One big achievement in modern condensed matter physics is the recognition of\nthe importance of various band geometric quantities in physical effects. As\nprominent examples, Berry curvature and the Berry curvature dipole are\nconnected to the linear and the second-order Hall effects, respectively. Here,\nwe show that the Berry connection polarizability (BCP) tensor, as another\nintrinsic band geometric quantity, plays a key role in the third-order Hall\neffect. Based on the extended semiclassical formalism, we develop a theory for\nthe third-order charge transport and derive explicit formulas for the\nthird-order conductivity. Our theory is applied to the two-dimensional (2D)\nDirac model to investigate the essential features of the BCP and the\nthird-order Hall response. We further demonstrate the combination of our theory\nwith the first-principles calculations to study a concrete material system, the\nmonolayer FeSe. Our work establishes a foundation for the study of third-order\ntransport effects, and reveals the third-order Hall effect as a tool for\ncharacterizing a large class of materials and for probing the BCP in band\nstructure.",
        "positive": "Random matrix theory of quantum transport in chaotic cavities with\n  non-ideal leads: We determine the joint probability density function (JPDF) of reflection\neigenvalues in three Dyson's ensembles of normal-conducting chaotic cavities\ncoupled to the outside world through both ballistic and tunnel point contacts.\nExpressing the JPDF in terms of hypergeometric functions of matrix arguments\n(labeled by the Dyson index $\\beta$), we further show that reflection\neigenvalues form a determinantal ensemble at $\\beta=2$ and a new type of a\nPfaffian ensemble at $\\beta=4$. As an application, we derive a simple analytic\nexpression for the concurrence distribution describing production of orbitally\nentangled electrons in chaotic cavities with tunnel point contacts when time\nreversal symmetry is preserved."
    },
    {
        "anchor": "Enhanced quantum nonlinearities in a two mode optomechanical system: In cavity optomechanics, nanomechanical motion couples to a localized optical\nmode. The regime of single-photon strong coupling is reached when the optical\nshift induced by a single phonon becomes comparable to the cavity linewidth. We\nconsider a setup in this regime comprising two optical modes and one mechanical\nmode. For mechanical frequencies nearly resonant to the optical level\nsplitting, we find the photon-phonon and the photon-photon interactions to be\nsignificantly enhanced. In addition to dispersive phonon detection in a novel\nregime, this offers the prospect of optomechanical photon measurement. We study\nthese QND detection processes using both analytical and numerical approaches.",
        "positive": "Square-root higher-order topological insulator on a decorated honeycomb\n  lattice: Square-root topological insulators are recently-proposed intriguing\ntopological insulators, where the topologically nontrivial nature of Bloch wave\nfunctions is inherited from the square of the Hamiltonian. In this paper, we\npropose that higher-order topological insulators can also have their\nsquare-root descendants, which we term square-root higher-order topological\ninsulators. There, emergence of in-gap corner states is inherited from the\nsquared Hamiltonian which hosts higher-order topology. As an example of such\nsystems, we investigate the tight-binding model on a decorated honeycomb\nlattice, whose squared Hamiltonian includes a breathing kagome-lattice model, a\nwell-known example of higher-order topological insulators. We show that the\nin-gap corner states appear at finite energies, which coincides with the\nnon-trivial bulk polarization. We further show that the existence of in-gap\ncorner states results in characteristic single-particle dynamics, namely,\nsetting the initial state to be localized at the corner, the particle stays at\nthe corner even after a long time. Such characteristic dynamics may\nexperimentally be detectable in photonic crystals."
    },
    {
        "anchor": "Chain-like transitions in Wigner crystals: Sequential or non-sequential?: The structural transitions of the ground state of a system of repulsively\ninteracting particles confined in a quasi-one-dimensional channel, and the\neffect of the interparticle interaction as well as the functional form of the\nconfinement potential on those transitions are investigated. Although the\nnon-sequential ordering of transitions (non-SOT), i.e.\n$1$-$2$-$4$-$3$-$4$-$5$-$6$-$...$ sequence of chain configurations with\nincreasing density, is widely robust as predicted in a number of theoretical\nstudies, the sequential ordering of transitions (SOT),\ni.e.~$1$-$2$-$3$-$4$-$5$-$6$-$...$ chain, is found as the ground state for\nlong-ranged interparticle interaction and hard-wall-like confinement\npotentials. We found an energy barrier between every two different phases\naround its transition point, which plays an important role in the preference of\nthe system to follow either a SOT or a non-SOT. However, that preferential\ntransition requires also the stability of the phases during the transition.\nAdditionally, we analyze the effect of a small structural disorder on the\ntransition between the two phases around its transition point. Our results show\nthat a small deformation of the triangular structure, change dramatically the\npicture of the transition between two phases, removing in a considerable region\nthe non-SOT in the system. This feature could explain the fact that the non-SOT\nis, up to now, not observed in experimental systems, and suggests a more\nadvanced experimental set-up to detect the non-SOT.",
        "positive": "The $8Pmmn$ borophene sheet: A solid-state platform for space-time\n  engineering: We construct the most generic Hamiltonian of the $8Pmmn$ structure of\nborophene sheet in presence of spin-orbit, as well as background electric and\nmagnetic fields. In addition to spin and valley Hall effects, this structure\noffers a framework to conveniently manipulate the resulting \"tilt\" of the Dirac\nequation by applying appropriate electric fields. Therefore, the tilt can be\nmade space-, as well as time-dependent. The border separating the low-field\nregion with under-tilted Dirac fermions from the high-field region with\nover-tilted Dirac fermions will correspond to a black-hole horizon. In this\nway, space-time dependent electric fields can be used to design the metric of\nthe resulting space-time felt by electrons and holes satisfying the tilted\nDirac equation. Our platform offers a way to generate analogues of\ngravitational waves by electric fields (instead of mass sources) which can be\ndetected in solid state spectroscopies as waves of enhanced superconducting\ncorrelations."
    },
    {
        "anchor": "Kondo effect in side coupled double quantum-dot molecule: Electron tunneling through a double quantum dot molecule side attached to a\nquantum wire, in the Kondo regime, is studied. The mean-field finite-U\nslave-boson formalism is used to obtain the solution of the problem. We found\nconductance cancelations when the molecular energies of the side attached\ndouble quantum-dot cross the Fermi energy. We investigate the many body\nmolecular Kondo states as a function of the parameters of the system.",
        "positive": "Enhanced Gilbert Damping in Thin Ferromagnetic Films: Using a scattering matrix approach, the precession of the magnetization of a\nferromagnet is shown to transfer spins into adjacent normal metal layers. This\n``pumping'' of spins slows down the precession corresponding to an enhanced\nGilbert damping factor in the Landau-Lifshitz equation. The damping is\nexpressed in terms of the scattering matrix of the ferromagnet-normal metal\ninterface, which is accessible to model and first-principles calculations. Our\nestimates for permalloy thin films explain the trends observed in recent\nexperiments."
    },
    {
        "anchor": "K-matrices for non-abelian quantum Hall states: Two fundamental aspects of so-called non-abelian quantum Hall states (the\nq-pfaffian states and more general) are a (generalized) pairing of the\nparticipating electrons and the non-abelian statistics of the quasi-hole\nexcitations. In this paper, we show that these two aspects are linked by a\nduality relation, which can be made manifest by considering the K-matrices that\ndescribe the exclusion statistics of the fundamental excitations in these\nsystems.",
        "positive": "Tunneling from a correlated 2D electron system transverse to a magnetic\n  field: We show that, in a magnetic field parallel to the 2D electron layer, strong\nelectron correlations change the rate of tunneling from the layer\nexponentially. It results in a specific density dependence of the escape rate.\nThe mechanism is a dynamical Mossbauer-type recoil, in which the Hall momentum\nof the tunneling electron is partly transferred to the whole electron system,\ndepending on the interrelation between the rate of interelectron momentum\nexchange and the tunneling duration. We also show that, in a certain\ntemperature range, magnetic field can enhance rather than suppress the\ntunneling rate. The effect is due to the magnetic field induced energy exchange\nbetween the in-plane and out-of-plane motion. Magnetic field can also induce\nswitching between intra-well states from which the system tunnels, and a\ntransition from tunneling to thermal activation. Explicit results are obtained\nfor a Wigner crystal. They are in qualitative and quantitative agreement with\nthe relevant experimental data, with no adjustable parameters."
    },
    {
        "anchor": "Optical conductivity of the Weyl semimetal NbP: The optical properties of (001)-oriented NbP single crystals have been\nstudied in a wide spectral range from 6 meV to 3 eV from room temperature down\nto 10 K. The itinerant carriers lead to a Drude-like contribution to the\noptical response; we can further identify two pronounced phonon modes and\ninterband transitions starting already at rather low frequencies. By comparing\nour experimental findings to the calculated interband optical conductivity, we\ncan assign the features observed in the measured conductivity to certain\ninterband transitions. In particular, we find that transitions between the\nelectronic bands spilt by spin-orbit coupling dominate the interband\nconductivity of NbP below 100 meV. At low temperatures, the momentum-relaxing\nscattering rate of the itinerant carriers in NbP is very small, leading to\nmacroscopic characteristic length scales of the momentum relaxation of\napproximately 0.5 $\\mu$m.",
        "positive": "Optimized proximity thermometer for ultra-sensitive detection: We present a set of experiments to optimize the performance of the\nnoninvasive thermometer based on proximity superconductivity. Current through a\nstandard tunnel junction between an aluminum superconductor and a copper\nelectrode is controlled by the strength of the proximity induced to this normal\nmetal, which in turn is determined by the position of a direct superconducting\ncontact from the tunnel junction. Several devices with different distances were\ntested. We develop a theoretical model based on Usadel equations and dynamic\nCoulomb blockade which reproduces the measured results and yields a tool to\ncalibrate the thermometer and to optimize it further in future experiments."
    },
    {
        "anchor": "Electrical current noise of a beam splitter as a test of\n  spin-entanglement: We investigate the spin entanglement in the superconductor-quantum dot system\nproposed by Recher, Sukhorukov and Loss, coupling it to an electronic\nbeam-splitter. The superconductor-quantum dot entangler and the beam-splitter\nare treated within a unified framework and the entanglement is detected via\ncurrent correlations. The state emitted by the entangler is found to be a\nlinear superposition of non-local spin-singlets at different energies, a\nspin-entangled two-particle wavepacket. Colliding the two electrons in the\nbeam-splitter, the singlet spin-state gives rise to a bunching behavior,\ndetectable via the current correlators. The amount of bunching depends on the\nrelative positions of the single particle levels in the quantum dots and the\nscattering amplitudes of the beam-splitter. The singlet spin entanglement,\ninsensitive to orbital dephasing but suppressed by spin dephasing, is\nconveniently quantified via the Fano factors. It is found that the\nentanglement-dependent contribution to the Fano factor is of the same magnitude\nas the non-entangled, making an experimental detection feasible. A detailed\ncomparison between the current correlations of the non-local spin-singlet state\nand other states, possibly emitted by the entangler, is performed. This\nprovides conditions for an unambiguous identification of the non-local singlet\nspin entanglement.",
        "positive": "Anisotropic Ballistic Transport Revealed by Molecular Nanoprobe\n  Experiments: Atomic-scale charge transport properties are not only of significant\nfundamental interest but also highly relevant for numerous technical\napplications. However, experimental methods which are capable of detecting\ncharge transport at the relevant single-digit nanometer length scales are\nscarce. Here we report on molecular nanoprobe (MONA) experiments on Pd(110)\nwhere we utilize the charge carrier-driven switching of a single cis-2-butene\nmolecule to detect ballistic transport properties over length scales of a few\nnanometers. Our data demonstrate a striking angular dependence with a dip in\ncharge transport along the [1-10]-oriented atomic rows and a peak in the\ntransverse [001] direction. The narrow angular width of both features and\ndistance-dependent measurements suggest that the nanometer-scale ballistic\ntransport properties of metallic surfaces is significantly influenced by the\natomic structure."
    },
    {
        "anchor": "Using spin bias to manipulate and measure quantum spin in quantum dots: A double-quantum-dot coupled to electrodes with spin-dependent splitting of\nchemical potentials (spin bias) is investigated theoretically by means of the\nGreen's functions formalism. By applying a large spin bias, the quantum spin in\na quantum dot (the dot 1) can be manipulated in a fully electrical manner. To\nnoninvasively monitor the manipulation of the quantum spin in the dot 1, it is\nproposed that the second quantum dot (the dot 2) is weakly coupled to the dot\n1. In the presence of the exchange interaction between the two dots, the\npolarized spin in the dot 1 behaves like an effective magnetic field and weakly\npolarizes the spin in the nearby quantum dot 2. By applying a very small spin\nbias to the dot 2, the spin-dependent transport through the dot 2 can be\nprobed, allowing the spin polarization in the dot 1 to be identified\nnondestructively. These two steps form a complete scheme to manipulate a\ntrapped spin while permitting this manipulation to be monitored in the\ndouble-dot system using pure electric approaches.",
        "positive": "Wigner model for quantum transport in graphene: The single graphene layer is a novel material consisting of a flat monolayer\nof carbon atoms packed in a two-dimensional honeycomb-lattice, in which the\nelectron dynamics is governed by the Dirac equation. A pseudo-spin phase-space\napproach based on the Wigner-Weyl formalism is used to describe the transport\nof electrons in graphene including quantum effects. Our full-quantum mechanical\nrepresentation of the particles reveals itself to be particularly close to the\nclassical description of the particle motion. We analyze the Klein tunneling\nand the correction to the total current in graphene induced by this phenomenon.\nThe equations of motion are analytically investigated and some numerical tests\nare presented. The temporal evolution of the electron-hole pairs in the\npresence of an external electric field and a rigid potential step is\ninvestigated. The connection of our formalism with the Barry-phase approach is\nalso discussed."
    },
    {
        "anchor": "Dissipative soliton protocols in semiconductor microcavities at finite\n  temperatures: We consider exciton polaritons in a semiconductor microcavity with a\nsaturable absorber in the growth direction of the heterostructure. This feature\npromotes additional nonlinear losses of the system with the emergence of\nbistability of the condensate particles number on the nonresonant (electrical\nor optical) excitation intensity. Further we demonstrate a new type of bright\nspatial dissipative exciton-polariton soliton which emerges in the equilibrium\nbetween the regions with different particle density. We develop protocols of\nsoliton creation and destruction. The switch to a soliton-like behavior occurs\nif the cavity is exposed by a short strong laser pulse with certain energy and\nduration. We estimate the characteristic times of soliton switch on and off and\nthe time of return to the initial cycle. In particular, we demonstrate\nsurprising narrowing of the spatial profile of the soliton and its vanishing at\ncertain temperature due to interaction of the system with the thermal bath of\nacoustic phonons. We also address the role of polariton-polariton interaction\n(Kerr-like nonlinearity) on formation of dissipative solitons and show that the\nsoliton may exist both in its presence and absence.",
        "positive": "Nonequilibrium plasmons and transport properties of a double--junction\n  quantum wire: We study theoretically the current-voltage characteristics, shot noise, and\nfull counting statistics of a quantum wire double barrier structure. We model\neach wire segment by a spinless Luttinger liquid. Within the sequential\ntunneling approach, we describe the system's dynamics using a master equation.\nWe show that at finite bias the non-equilibrium distribution of plasmons in the\ncentral wire segment leads to increased average current, enhanced shot noise,\nand full counting statistics corresponding to a super-Poissonian process. These\neffects are particularly pronounced in the strong interaction regime, while in\nthe non-interacting case we recover results obtained earlier using detailed\nbalance arguments."
    },
    {
        "anchor": "Determination of spin-orbit torque efficiencies in heterostructures with\n  in-plane magnetic anisotropy: It has been shown that the spin Hall effect from heavy transition metals can\ngenerate sufficient spin-orbit torque and further produce current-induced\nmagnetization switching in the adjacent ferromagnetic layer. However, if the\nferromagnetic layer has in-plane magnetic anisotropy, probing such switching\nphenomenon typically relies on tunneling magnetoresistance measurement of\nnano-sized magnetic tunnel junctions, differential planar Hall voltage\nmeasurement, or Kerr imaging approaches. We show that in magnetic\nheterostructures with spin Hall metals, there exist current-induced in-plane\nspin Hall effective fields and unidirectional magnetoresistance that will\nmodify their anisotropic magnetoresistance behavior. We also demonstrate that\nby analyzing the response of anisotropic magnetoresistance under such\ninfluences, one can directly and electrically probe magnetization switching\ndriven by the spin-orbit torque, even in micron-sized devices. This pump-probe\nmethod allows for efficient and direct determination of key parameters from\nspin-orbit torque switching events without lengthy device fabrication\nprocesses.",
        "positive": "Voltage Dependence of Spin Polarized Tunneling: A mesoscopic spin valve is used to determine the effective spin polarization\nof electrons tunneling from and into ferromagnetic transition metals at finite\nvoltages. The tunneling spin polarization from the ferromagnet (FM) slowly\ndecreases with bias, but drops faster and even inverts with voltage when\nelectrons tunnel into it. A bias-dependent free electron model shows that in\nthe former case electrons originate near the Fermi level of the FM with large\npolarization whereas in the latter, electrons tunnel into hot electron states\nfor which the polarization is significantly reduced. The change in sign is\nascribed to the detailed matching of the electron wave function through the\ntunnel barrier."
    },
    {
        "anchor": "Localized states of an excess electron in ionic clusters: A theory for an electron affinity of ionic clusters is proposed both in a\nquasiclassical approach and with quantization of a polarization electric field\nin a nanoparticle. An interaction of an electron with longitudinal optical\nphonons in an ionic cluster is described. A critical size of the cluster\nregarding in formation of an electron's autolocalized state, dependencies of an\nenergy and a radius of a polaron on a cluster's size are obtained by a\nvariational method. It has been found that a binding energy of the electron in\na cluster depends on a cluster's radius but the radius of electron's\nautolocalization does not depend on cluster's radius and equals to the polaron\nradius in a corresponding infinity crystal, moreover the bound state of the\nelectron in a cluster is possible if the cluster's radius is more then the\npolaron radius. A perturbation method for finding of the critical parameters is\nproposed, where an dependence of the critical size on a momentum of an electron\nin a conduction band is observed.",
        "positive": "Emergence of magnetism in graphene materials and nanostructures: Magnetic materials and nanostructures based on carbon offer unique\nopportunities for future technological applications such as spintronics. This\narticle reviews graphene-derived systems in which magnetic correlations emerge\nas a result of reduced dimensions, disorder and other possible scenarios. In\nparticular, zero-dimensional graphene nanofragments, one-dimensional graphene\nnanoribbons, and defect-induced magnetism in graphene and graphite are covered.\nPossible physical mechanisms of the emergence of magnetism in these systems are\nillustrated with the help of computational examples based on simple model\nHamiltonians. In addition, this review covers spin transport properties,\nproposed designs of graphene-based spintronic devices, magnetic ordering at\nfinite temperatures as well as the most recent experimental achievements."
    },
    {
        "anchor": "Ordering in SU(4)-symmetric model of AA bilayer graphene: We examine possible ordered states of AA stacked bilayer graphene arising due\nto electron-electron coupling. We show that under certain assumptions the\nHamiltonian of the system possesses an SU(4) symmetry. The multicomponent order\nparameter is described by a $4\\times4$ matrix $\\hat{Q}$, for which a mean-field\nself-consistency equation is derived. This equation allows Hermitian and\nnon-Hermitian solutions. Hermitian solutions can be grouped into three\ntopologically-distinct classes. First class corresponds to the charge density\nwave. Second class includes spin density wave, valley density wave, and\nspin-valley density wave. An ordered state in the third class is a combination\nof all the aforementioned density-wave types. For anti-Hermitian $\\hat{Q}$ the\nordered states are characterized by spontaneous inter-layer loop currents\nflowing in the bilayer. Depending on the topological class of the solution\nthese currents can carry charge, spin, valley, and spin-valley quanta. We also\ndiscuss the special case when matrix $\\hat{Q}$ is not Hermitian and not\nanti-Hermitian. Utility and weak points of the proposed SU(4)-based\nclassification scheme of the ordered states are analyzed.",
        "positive": "Down-conversion of quantum fluctuations of photonic heat current in a\n  circuit: We discuss the non-zero frequency noise of heat current with the explicit\nexample of energy carried by thermal photons in a circuit. Instead of the\nstandard circuit modelling that gives a convenient way of predicting\ntime-averaged heat current, we describe a setup composed of two resistors\nforming the heat baths by collections of bosonic oscillators. In terms of\naverage heat transport this model leads to identical results with the\nconventional one, but besides this, it yields a convenient way of dealing with\nnoise as well. The non-zero frequency heat current noise does not vanish in\nequilibrium even at zero temperature, the result that is known for, e.g.,\nelectron tunneling. We present a modulation method that can convert the\ndifficult-to-measure high frequency quantum noise down to zero frequency."
    },
    {
        "anchor": "Bose-Einstein condensates in fast rotation: In this short review we present our recent results concerning the rotation of\natomic Bose-Einstein condensates confined in quadratic or quartic potentials,\nand give an overview of the field. We first describe the procedure used to set\nan atomic gas in rotation and briefly discuss the physics of condensates\ncontaining a single vortex line. We then address the regime of fast rotation in\nharmonic traps, where the rotation frequency is close to the trapping\nfrequency. In this limit the Landau Level formalism is well suited to describe\nthe system. The problem of the condensation temperature of a fast rotating gas\nis discussed, as well as the equilibrium shape of the cloud and the structure\nof the vortex lattice. Finally we review results obtained with a quadratic +\nquartic potential, which allows to study a regime where the rotation frequency\nis equal to or larger than the harmonic trapping frequency.",
        "positive": "Supercurrent Flow in Multi-Terminal Graphene Josephson Junctions: We investigate the electronic properties of ballistic planar Josephson\njunctions with multiple superconducting terminals. Our devices consist of\nmonolayer graphene encapsulated in boron nitride with molybdenum-rhenium\ncontacts. Resistance measurements yield multiple resonant features, which are\nattributed to supercurrent flow among adjacent and non-adjacent Josephson\njunctions. In particular, we find that superconducting and dissipative currents\ncoexist within the same region of graphene. We show that the presence of\ndissipative currents primarily results in electron heating and estimate the\nassociated temperature rise. We find that the electrons in encapsulated\ngraphene are efficiently cooled through the electron-phonon coupling."
    },
    {
        "anchor": "Graphene-coated holey metal films: tunable molecular sensing by surface\n  plasmon resonance: We report on the enhancement of surface plasmon resonances in a holey\nbidimensional grating of subwavelength size, drilled in a gold thin film coated\nby a graphene sheet. The enhancement originates from the coupling between\ncharge carriers in graphene and gold surface plasmons. The main plasmon\nresonance peak is located around 1.5 microns. A lower constraint on the\ngold-induced doping concentration of graphene is specified and the interest of\nthis architecture for molecular sensing is also highlighted.",
        "positive": "The effect of the glass transition in fullerite C60 on Ar impurity\n  diffusion: The kinetics of sorption and subsequent desorption of argon gas by a C60\npowder has been investigated in the temperature interval 58-290 K. The\ntemperature dependence of the coefficients of Ar diffusion in fullerite has\nbeen obtained using the measured characteristic times of sorption. The\ndiffusion coefficients of Ar decrease monotonically with lowering temperature\nin the whole range of the investigated temperatures, which corresponds to the\nthermally activated diffusion of Ar atoms in fullerite. The glass transition in\nfullerite induces an order-of-magnitude decrease in the activation energy of Ar\ndiffusion in fullerite. Most likely this is because new directions may appear\ndue to the glass transition in which the barriers separating the interstitial\nvoids in the C60 lattice are significantly lower"
    },
    {
        "anchor": "A quantum bound on the 1/f noise in semiconductors with a conical\n  energy-momentum dispersion: The quantum indeterminacy caused by non-commutativity of observables at\ndifferent times sets a lower bound on the voltage noise power spectrum in any\nconducting material. This bound is calculated explicitly in the case of\nsemiconductors with a conical energy-momentum dispersion of charge carriers. It\npossesses all characteristic properties of 1/f noise. Its momentum\ndecomposition is found to be singular at zero particle momentum, a measurable\nconsequence being a sharp peak in the noise magnitude at small charge carrier\ndensity. In application to monolayer graphene, this peak becomes M-shaped on\naccount of a continuous transition from the electron to hole conductivity. A\ncomparison with experimental data is made which demonstrates that the\ncalculated power spectrum is close in magnitude and congruent to the observed.",
        "positive": "Nuclear Magnetic Relaxation and Knight Shift Due to Orbital Interaction\n  in Dirac Electron Systems: We study the nuclear magnetic relaxation rate and Knight shift in the\npresence of the orbital and quadrupole interactions for three-dimensional Dirac\nelectron systems (e.g., bismuth-antimony alloys). By using recent results of\nthe dynamic magnetic susceptibility and permittivity, we obtain rigorous\nresults of the relaxation rates $(1/T_1)_{\\rm orb}$ and $(1/T_1)_{\\rm Q}$,\nwhich are due to the orbital and quadrupole interactions, respectively, and\nshow that $(1/T_1)_{\\rm Q}$ gives a negligible contribution compared with\n$(1/T_1)_{\\rm orb}$. It is found that $(1/T_1)_{\\rm orb}$ exhibits anomalous\ndependences on temperature $T$ and chemical potential $\\mu$. When $\\mu$ is\ninside the band gap, $(1/T_1)_{\\rm orb} \\sim T ^3 \\log (2 T/\\omega_0)$ for\ntemperatures above the band gap, where $\\omega_0$ is the nuclear Larmor\nfrequency. When $\\mu$ lies in the conduction or valence bands, $(1/T_1)_{\\rm\norb} \\propto T k_{\\rm F}^2 \\log (2 |v_{\\rm F}| k_{\\rm F}/\\omega_0)$ for low\ntemperatures, where $k_{\\rm F}$ and $v_{\\rm F}$ are the Fermi momentum and\nFermi velocity, respectively. The Knight shift $K_{\\rm orb}$ due to the orbital\ninteraction also shows anomalous dependences on $T$ and $\\mu$. It is shown that\n$K_{\\rm orb}$ is negative and its magnitude significantly increases with\ndecreasing temperature when $\\mu$ is located in the band gap. Because the\nanomalous dependences in $K_{\\rm orb}$ is caused by the interband particle-hole\nexcitations across the small band gap while $\\left( 1/T_1 \\right)_{\\rm orb}$ is\ngoverned by the intraband excitations, the Korringa relation does not hold in\nthe Dirac electron systems."
    },
    {
        "anchor": "Creating and detecting poor man's Majorana bound states in interacting\n  quantum dots: We propose and theoretically investigate an alternative way to create the\npoor man's Majorana bound states (MBSs) introduced in Phys. Rev. B 86, 134528\n(2012). Our proposal is based on two quantum dots (QDs) with strong\nelectron-electron interactions that couple via a central QD with\nproximity-induced superconductivity. In the presence of spin-orbit coupling and\na magnetic field, gate control of all three QDs allows tuning the system into\nsweet spots with one MBS localized on each outer dot. We quantify the quality\nof these MBSs and show how it depends on the Zeeman energy and interaction\nstrength. We also show how nonlocal transport spectroscopy can be used to\nidentify sweet spots with high MBS quality. Our results provide a path for\ninvestigating MBS physics in a setting that is free of many of the doubts and\nuncertainties that plague other platforms.",
        "positive": "Spintronic devices as next-generation computation accelerators: The ever increasing demand for computational power combined with the\npredicted plateau for the miniaturization of existing silicon-based\ntechnologies has made the search for low power alternatives an industrial and\nscientifically engaging problem. In this work, we explore spintronics-based\nIsing machines as hardware computation accelerators. We start by presenting the\nphysical platforms on which this emerging field is being developed, the\ndifferent control schemes and the type of algorithms and problems on which\nthese machines outperform conventional computers. We then benchmark these\ntechnologies and provide an outlook for future developments and use-cases that\ncan help them get a running start for integration into the next generation of\ncomputing devices."
    },
    {
        "anchor": "Scattering theory of chiral Majorana fermion interferometry: Using scattering theory, we investigate interferometers composed of chiral\nMajorana fermion modes coupled to normal metal leads. We advance an approach in\nwhich also the basis states in the normal leads are written in terms of\nMajorana modes. Thus each pair of electron-hole states is associated with a\npair of Majorana modes. Only one lead Majorana mode couples to the intrinsic\nMajorana mode whereas its partner is completely reflected. Similarly the\nremaining Majorana modes are completely reflected but in general mix pair-wise.\nWe demonstrate that the charge current can also be expressed in terms of\ninterference between pairs of Majorana modes. These two basic facts permit a\ntreatment and understanding of current and noise signatures of chiral Majorana\nfermion interferometry in an especially elegant way. As a particular example of\napplications, in Fabry-Perot-type interferometers where chiral Majorana modes\nform loops, resonances (anti-resonances) from such loops always lead to peaked\n(suppressed) Andreev differential conductances, and negative (positive)\ncross-correlations that originate purely from two-Majorana-fermion exchange.\nThese investigations are intimately related to current and noise signatures of\nMajorana bound states.",
        "positive": "Converse Flexoelectricity of Low-Dimensional Bismuth Selenite (Bi2Se3)\n  Revealed by Piezoresponse Force Microscopy (PFM): Many kinds of two-dimensional (2D) van der Waals (vdW) have been demonstrated\nto exhibit electromechanical coupling effects, which makes them promising\ncandidates for next-generation devices, such as piezotronics and\nnanogenerators. Recently, flexoelectricity was found to account for the\nout-of-plane electromechanical coupling in many 2D transition metal\ndichalcogenides (TMDs) who only exhibit in-plane piezoelectricity. However, low\ndimensional vdW three-dimensional (3D) topological insulators (TIs) have been\noverlooked regarding their electromechanical properties. In this study, for the\nfirst time, we experimentally investigate the electromechanical coupling of low\ndimensional 3D TIs with a centrosymmetric crystal structure, where a binary\ncompound, bismuth selenite (Bi2Se3), is taken as an example. The results of\npiezoresponse force microscope (PFM) tests on the Bi2Se3 nanoflakes show that\nthe material exhibits both out-of-plane and in-plane electromechanical\nresponses. The Bi2Se3 nanoflake with a thickness of 37 nm possesses an\neffective out-of-plane piezoelectric coefficient of ~0.65 pm V-1. With careful\nanalyses, the electromechanical responses are verified to arise from the\nconverse flexoelectricity. The measured effective out-of-plane piezoelectric\ncoefficient is mainly contributed by flexoelectric coefficient, {\\mu}_39, which\nis estimated to be approximately 0.13 nC m-1. However, it is rather difficult\nto obtain the in-plane component of the flexoelectric tensor from the in-plane\nPFM measurements since the direction of the in-plane stress is always not\nnormal to the AFM cantilever axis. The results provide useful guidance for\nunderstanding the flexoelectric effect of low dimensional vdW materials with\ncentrosymmetric crystal structures. Moreover, the work can pave to way to\nexplore the electromechanical devices based on the flexoelectricity of vdW TIs."
    },
    {
        "anchor": "Frequency Stability of Spin-Hall Nano-Oscillators with Realistic Grain\n  Structure: Nano-constriction spin-Hall nano-oscillators (NC-SHNOs) are one of the most\npromising alternatives among the microwave spintronics devices. They can\nprovide highly coherent and widely tuneable microwave signals and can be\nfabricated at low temperatures, which makes them compatible with\nback-end-of-the-line CMOS processing. For its applications, the frequency\nstability of each device is crucial, in particular for synchronization of\noscillator arrays. In this work, we focus on the influence of a realistic grain\nstructure on the SHNO frequency stability using both measurements as well as\nmicromagnetic simulations. Grains in the thin ferromagnetic metal films can\ninfluence the output characteristic of the SHNO since the exchange coupling is\nreduced locally at the grain boundaries. This work provides a novel\nmicromagnetic simulation method, for systematic investigation of frequency\ninstability or variability from device-to-device. Experimentally, a\ndevice-to-device frequency variability of ~270 MHz was found and in some\nextreme cases, a double-mode oscillation was observed in the high current\noperation range. This oscillation behavior was reproduced in simulations, where\nthe inclusion of grains resulted in a frequency variability of ~100 MHz and\ndouble-mode oscillations for some particular configurations. The double modes\nare consistent with a partial decoupling, or non-coherent operation, of two\noscillating regions located at the nano-constriction edges.",
        "positive": "Phonon signatures in spectra of exciton polaritons in transition metal\n  dichalcogenides: Embedding a monolayer of a transition metal dichalcogenide in a high-Q\noptical cavity results in the formation of distinct exciton polariton modes.\nThe polaritons are affected by the strong exciton-phonon interaction in the\nmonolayer. We use a time convolutionless master equation to calculate the\nphonon influence on the spectra of the polaritons. We discuss the non-trivial\ndependence of the line shapes of both branches on temperature and detuning. The\npeculiar polariton dispersion relation results in a linewidth of the lower\npolariton being largely independent of the coupling to acoustic phonons. For\nthe upper polariton, acoustic phonons lead to a low-energy shoulder of the\nresonance in the linear response. Furthermore, we analyze the influence of\ninhomogeneous broadening being the dominant contribution to the lower polariton\nlinewidth at low temperatures. Our results point towards interesting phonon\nfeatures in polariton spectra in transition metal dichalcogenides."
    },
    {
        "anchor": "Detecting the spin-polarization of edge states in graphene nanoribbons: Low dimensional carbon-based materials are interesting because they can show\nintrinsic $\\pi$-magnetism associated to p-electrons residing in specific\nopen-shell configurations. Consequently, during the last years there have been\nimpressive advances in the field combining indirect experimental fingerprints\nof localized magnetic moments with theoretical models. In spite of that, a\ncharacterization of their spatial- and energy-resolved spin-moment has so far\nremained elusive. To obtain this information, we present an approach based on\nthe stabilization of the magnetization of $\\pi$-orbitals by virtue of a\nsupporting substrate with ferromagnetic ground state. Remarkably, we go beyond\nlocalized magnetic moments in radical or faulty carbon sites: In our study,\nenergy-dependent spin-moment distributions have been extracted from spatially\nextended one-dimensional edge states of chiral graphene nanoribbons. This\nmethod can be generalized to other nanographene structures, representing an\nessential validation of these materials for their use in spintronics and\nquantum technologies.",
        "positive": "Time-resolved Photoluminescence in Terahertz-driven Hybrid Systems of\n  Plasmons and Excitons: Ultrafast pump-probe technique is a powerful tool to understand and\nmanipulate properties of materials for designing novel quantum devices. An\nintense, single cycle terahertz pulse can change the intrinsic properties of\nsemiconductor quantum dots to have different luminescence. In a hybrid system\nof plasmon and exciton, the coherence and coupling between these two degrees of\nfreedom play an important role on their optical properties. Therefore, we\nconsider a terahertz pump optical probe experiment in the hybrid systems where\nthe terahertz pump pulse couples to the exciton degrees of freedom on the\nquantum dot. The time resolved photoluminescence of the hybrid system shows\nthat the response of the characteristic frequency shifts according to the\noverlap between the pump and probe pulses. Furthermore, the resonance between\nthe exciton and plasmons can be induced by the terahertz pump pulse in some\nparameter regimes. Our results show the terahertz driven hybrid system can be a\nversatile tool for manipulating the material properties and open a new route to\ndesign modern optical devices."
    },
    {
        "anchor": "MagnetoResistance of graphene-based spin valves: We study the magnetoresistance of spin-valve devices using graphene as a\nnon-magnetic material to connect ferromagnetic leads. As a preliminary step we\nfirst study the conductivity of a graphene strip connected to metallic contacts\nfor a variety of lead parameters, and demonstrate that the resulting\nconductivity is rather insensitive to them. We then compute the conductivity of\nthe spin-valve device in the parallel and antiparallel spin polarization\nconfigurations, and find that it depends only weakly on the relative spin\norientations of the leads, so that the magnetoresistance $MR$ of the system is\nvery small. The smallness of $MR$ is a consequence of the near independence of\nthe graphene conductivity from the electronic details of the leads. Our results\nindicate that, although graphene has properties that make it attractive for\nspintronic devices, the performance of an graphene-based spin-valve is likely\nto be poor.",
        "positive": "Self-assembled cyclic oligothiophene nanotubes: electronic properties\n  from a dispersion-corrected hybrid functional: The band structure and size-scaling of electronic properties in\nself-assembled cyclic oligothiophene nanotubes are investigated using density\nfunctional theory (DFT) for the first time. In these unique tubular aggregates,\nthe {\\pi}-{\\pi} stacking interactions between adjacent monomers provide\npathways for charge transport and energy migration along the periodic\none-dimensional nanostructure. In order to simultaneously describe both the\n{\\pi}-{\\pi} stacking interactions and the global electronic band structure of\nthese nanotubes, we utilize a dispersion-corrected B3LYP-D hybrid functional in\nconjunction with all-electron basis sets and one-dimensional periodic boundary\nconditions. Based on our B3LYP-D calculations, we present simple analytical\nformulas for estimating the fundamental band gaps of these unique nanotubes as\na function of size and diameter. Our results on these molecular nanostructures\nindicate that all of the oligothiophene nanotubes are direct-gap semiconductors\nwith band gaps ranging from 0.9 eV - 3.3 eV, depending on tube diameter and\noligothiophene orientation. These nanotubes have cohesive energies of up to\n2.43 eV per monomer, indicating future potential use in organic electronic\ndevices due to their tunable electronic band structure and high structural\nstability."
    },
    {
        "anchor": "Floquet boundary states in AB-stacked graphite: We report on the effect of laser illumination with circularly polarized light\non the electronic structure of AB-stacked graphite samples. By using Floquet\ntheory in combination with Green's function techniques, we find that the\npolarized light induces band-gap openings at the Floquet zone edge\n$\\hbar\\Omega/2$, bridged by chiral boundary states. These states propagate\nmainly along the borders of the constituting layers as evidenced by the\ntime-averaged local density of states and the probability current density in\nseveral geometries. Semianalytic calculations of the Chern number suggest that\nthese states are of topological nature, similar to those found in illuminated\n2D samples like monolayer and bilayer graphene. These states are promising\ncandidates for the realization of a three-dimensional version of the quantum\nHall effect for Floquet systems.",
        "positive": "Johnson-Nyquist noise in films and narrow wires: The Johnson-Nyquist noise in narrow wires having a transverse size smaller\nthan the screening length is shown to be white up to the frequency $D/L^2$ and\nto decay at higher frequencies as $\\omega^{-{1/2}}$. In two-dimensional films\nhaving a thickness smaller than the screening length, the Johnson-Nyquist noise\nis predicted to be frequency independent up to the frequency $\\sigma_{2D}/L$\nand to have a {\\it universal} $1/\\omega$ spectrum at higher frequencies. These\nresults are contrasted with the conventional noise spectra in neutral and\nthree-dimensional charged liquids."
    },
    {
        "anchor": "Measuring the magnetization of three monolayer thick Co islands and\n  films by X-ray dichroism: Co islands and films are characterized by x-ray magnetic circular dichroism\nphotoemission electron microscopy (XMCD-PEEM). The spatial resolution\ncapabilties of the technique together with atomic growth control permit\nobtaining perfectly flat triangular islands with a given thickness (3 ML), very\nclose to an abrupt spin-reorientation transition. The magnetic domain\nconfigurations are found to depend on island size: while small islands can be\nmagnetized in a single-domain state, larger islands show more complex patterns.\nFurthermore, the magnetization pattern of the larger islands presents a common\nchirality. By means of dichroic spectro-microscopy at the Co L absorption\nedges, an experimental estimate of the ratio of the spin- and orbital magnetic\nmoment for three monolayer thick films is obtained.",
        "positive": "Effect of nonhomogenous dielectric background on the plasmon modes in\n  graphene double-layer structures at finite temperatures: We have calculated the plasmon modes in graphene double layer structures at\nfinite temperatures, taking into account the inhomogeneity of the dielectric\nbackground of the system. The effective dielectric function is obtained from\nthe solution of the Poisson equation of three-layer dielectric medium with the\ngraphene sheets located at the interfaces, separating the different materials.\nDue to the momentum dispersion of the effective dielectric function, the intra-\nand inter-layer bare Coulomb interactions in the graphene double layer system\nacquires an additional momentum dependence--an effect that is of the order of\nthe inter-layer interaction itself. We show that the energies of the in-phase\nand out-of-phase plasmon modes are determined largely by different values of\nthe spatially dependent effective dielectric function. The effect of the\ndielectric inhomogeneity increases with temperature and even at high\ntemperatures the energy shift induced by the dielectric inhomogeneity and\ntemperature itself remains larger than the broadening of the plasmon energy\ndispersions due to the Landau damping. The obtained new features of the plasmon\ndispersions can be observed in frictional drag measurements and in inelastic\nlight scattering and electron energy-loss spectroscopies."
    },
    {
        "anchor": "Fabry-Perot Interferometry with Fractional Charges: Resistance oscillations in electronic Fabry-Perot interferometers near\nfractional quantum Hall (FQH) filling factors 1/3, 2/3, 4/3 and 5/3 in the\nconstrictions are compared to corresponding oscillations near integer quantum\nHall (IQH) filling factors in the constrictions, appearing in the same devices\nand at the same gate voltages. Two-dimensional plots of resistance versus gate\nvoltage and magnetic field indicate that all oscillations are Coulomb\ndominated. Applying a Coulomb charging model yields an effective tunneling\ncharge e* \\approx e/3 for all FQH constrictions and e* \\approx e for IQH\nconstrictions. Surprisingly, we find a common characteristic temperature for\nFQH oscillations and a different common characteristic temperature for IQH\noscillations.",
        "positive": "Spin-dependent transmission in waveguides with periodically modulated\n  strength of the spin-orbit interaction: The electron transmission $T$ is evaluated through waveguides, in which the\nstrength of the spin-orbit interaction(SOI) $\\alpha$ is varied periodically,\nusing the transfer-matrix technique. It is shown that $T$ exhibits a {\\it\nspin-transistor} action, as a function of $\\alpha$ or of the length of one of\nthe two subunits of the unit cell, provided only one mode is allowed to\npropagate in the waveguide. A similar but not periodic behavior occurs as a\nfunction of the incident electron energy. A transparent formula for $T$ through\none unit is obtained and helps explain its periodic behavior. The structure\nconsidered is a good candidate for the establishment of a realistic spin\ntransistor."
    },
    {
        "anchor": "Fractional charge oscillations in quantum spin Hall quantum dots: We show that correlated two-particle backscattering can induce fractional\ncharge oscillations in a quantum dot built at the edge of a two-dimensional\ntopological insulator by means of magnetic barriers. The result nicely\ncomplements recent works where the fractional oscillations were obtained\nemploying of semiclassical treatments. Moreover, since by rotating the\nmagnetization of the barriers a fractional charge can be trapped in the dot via\nthe Jackiw-Rebbi mechanism, the system we analyze offers the opportunity to\nstudy the interplay between this noninteracting charge fractionalization and\nthe fractionalization due to two-particle backscattering. In this context, we\ndemonstrate that the number of fractional oscillations of the charge density\ndepends on the magnetization angle. Finally, we address the renormalization\ninduced by two-particle backscattering on the spin density, which is\ncharacterized by a dominant oscillation, sensitive to the Jackiw-Rebbi charge,\nwith a wavelength twice as large as the charge density oscillations.",
        "positive": "Multi-scale approach to first-principles electron transport beyond 100\n  nm: Multi-scale computational approaches are important for studies of novel,\nlow-dimensional electronic devices since they are able to capture the different\nlength-scales involved in the device operation, and at the same time describe\ncritical parts such as surfaces, defects, interfaces, gates, and applied bias,\non a atomistic, quantum-chemical level. Here we present a multi-scale method\nwhich enables calculations of electronic currents in two-dimensional devices\nlarger than 100 nm$^2$, where multiple perturbed regions described by density\nfunctional theory (DFT) are embedded into an extended unperturbed region\ndescribed by a DFT-parametrized tight-binding model. We explain the details of\nthe method, provide examples, and point out the main challenges regarding its\npractical implementation. Finally we apply it to study current propagation in\npristine, defected and nanoporous graphene devices, injected by chemically\naccurate contacts simulating scanning tunneling microscopy probes."
    },
    {
        "anchor": "Kondo Effect in a Many-Electron Quantum Ring: The Kondo effect is investigated in a many-electron quantum ring as a\nfunction of magnetic field. For fields applied perpendicular to the plane of\nthe ring a modulation of the Kondo effect with the Aharonov-Bohm period is\nobserved. This effect is discussed in terms of the energy spectrum of the ring\nand the parametrically changing tunnel coupling. In addition, we use gate\nvoltages to modify the ground-state spin of the ring. The observed splitting of\nthe Kondo-related zero-bias anomaly in this configuration is tuned with an\nin-plane magnetic field.",
        "positive": "The crux of using the cascaded emission of a 3-level quantum ladder\n  system to generate indistinguishable photons: We investigate the degree of indistinguishability of cascaded photons emitted\nfrom a 3-level quantum ladder system; in our case the biexciton-exciton cascade\nof semiconductor quantum dots. For the 3-level quantum ladder system we\ntheoretically demonstrate that the indistinguishability is inherently limited\nfor both emitted photons and determined by the ratio of the lifetimes of the\nexcited and intermediate states. We experimentally confirm this finding by\ncomparing the quantum interference visibility of non-cascaded emission and\ncascaded emission from the same semiconductor quantum dot. Quantum optical\nsimulations produce very good agreement with the measurements and allow to\nexplore a large parameter space. Based on our model, we propose photonic\nstructures to optimize the lifetime ratio and overcome the limited\nindistinguishability of cascaded photon emission from a 3-level quantum ladder\nsystem."
    },
    {
        "anchor": "Advanced DFT-NEGF transport techniques for novel 2D-material and device\n  exploration including HfS2/WSe2 van-der-Waals Heterojunction TFET and\n  WTe2/WS2 metal/semiconductor contact: We present, here, advanced DFT-NEGF techniques that we have implemented in\nour ATOmistic MOdelling Solver, ATOMOS, to explore transport in novel materials\nand devices and in particular in van-der-Waals heterojunction transistors. We\ndescribe our methodologies using plane-wave DFT, followed by a Wannierization\nstep, and linear combination of atomic orbital DFT, that leads to an orthogonal\nand non-orthogonal NEGF model, respectively. We then describe in detail our\nnon-orthogonal NEGF implementation including the Sancho-Rubio and\nelectron-phonon scattering within a non-orthogonal framework. We also present\nour methodology to extract electron-phonon coupling from first principle and\ninclude them in our transport simulations. Finally, we apply our methods\ntowards the exploration of novel 2D materials and devices. This includes 2D\nmaterial selection and the Dynamically-Doped FET for ultimately scaled MOSFETS,\nthe exploration of vdW TFETs, in particular the HfS2/WSe2 TFET that could\nachieve high on-current levels, and the study of Schottky-barrier height and\ntransport through a metal-semiconducting WTe2/WS2 VDW junction transistor.",
        "positive": "Above-gap Conductance Anomaly Studied in\n  Superconductor-graphene-superconductor Josephson Junctions: We investigated the electrical transport properties of\nsuperconductor-graphene-superconductor (SGS) Josephson junctions. In low\nvoltage bias, we observed conventional proximity-coupled Josephson effect, such\nas the supercurrent flow through the graphene, sub-gap structure of\ndifferential conductance due to Andreev reflection, and periodic modulation of\nthe critical current Ic with perpendicular magnetic field H to the graphene. In\nhigh bias above the superconducting gap voltage, however, we also observed an\nanomalous jump of the differential conductance, the voltage position of which\nis sensitive to the backgate voltage Vg. Our extensive study with varying Vg,\ntemperature, and H reveals that the above-gap structure takes place at a\ncharacteristic power P*, which is irrespective of Vg for a given junction.\nTemperature and H dependences of P* are well explained by the increase of the\nelectron temperature in graphene."
    },
    {
        "anchor": "An investigation into the feasibility of myoglobin-based single-electron\n  transistors: Myoglobin single-electron transistors were investigated using nanometer- gap\nplatinum electrodes fabricated by electromigration at cryogenic temperatures.\nApomyoglobin (myoglobin without heme group) was used as a reference. The\nresults suggest single electron transport is mediated by resonant tunneling\nwith the electronic and vibrational levels of the heme group in a single\nprotein. They also represent a proof-of-principle that proteins with redox\ncenters across nanometer-gap electrodes can be utilized to fabricate\nsingle-electron transistors. The protein orientation and conformation may\nsignificantly affect the conductance of these devices. Future improvements in\ndevice reproducibility and yield will require control of these factors.",
        "positive": "Analysis of Vacancy defects in Hybrid Graphene-Boron Nitride Armchair\n  Nanoribbon based n-MOSFET at Ballistic Limit: Here, we report the performance of vacancy affected supercell of a hybrid\nGraphene-Boron Nitride embedded armchair nanoribbon (a-GNR-BN) based n-MOSFET\nat its ballistic transport limit using Non Equilibrium Green's Function (NEGF)\nmethodology. A supercell is made of the 3p configuration of armchair nanoribbon\nthat is doped on the either side with 6 BN atoms and is also H-passivated. The\ntype of vacancies studied are mono (B removal), di (B and N atom removal) and\nhole (removal of 6 atoms) formed all at the interface of carbon and BN atoms.\nDensity Functional Theory (DFT) is employed to evaluate the material properties\nof this supercell like bandgap, effective mass and density of states (DOS).\nFurther band gap and effective mass are utilized in self-consistent\nPoissonSchrodinger calculator formalized using NEGF approach. For all the\nvacancy defects, material properties show a decrease which is more significant\nfor hole defects. This observation is consistent in the device characteristics\nas well where ON-current (ION ) and Sub Threshold Slope (SS) shows the maximum\nincrement for hole vacancy and increase is more significant becomes when the\nnumber of defects increase."
    },
    {
        "anchor": "Thermoelectric efficiency of single-molecule junctions with long\n  molecular linkers: We report results of theoretical studies of thermoelectric efficiency of\nsingle-molecule junctions with long molecular linkers. The linker is simulated\nby a chain of identical sites described using a tight-binding model. It is\nshown that thermoelectric figure of merit ZT strongly depends on the bridge\nlength, being controlled by the lineshape of electron transmission function\nwithin the tunnel energy range corresponding to HOMO/LUMO transport channel.\nUsing the adopted model we demonstrate that ZT may significantly increase as\nthe linker lengthens, and that gateway states on the bridge (if any) may\nnoticeably affect the length-dependent ZT. Temperature dependences of ZT for\nvarious bridge lengths are analyzed. It is shown that broad minima emerge in ZT\nversus temperature curves whose positions are controlled by the bridge lengths.",
        "positive": "Cavity Control over Heavy-Hole Spin Qubits in Inversion-Symmetric\n  Crystals: The pseudospin of heavy-holes (HHs) confined in a semiconductor quantum dot\n(QD) represents a promising candidate for a fast and robust qubit. While hole\nspin manipulation by a classical electric field utilizing the Dresselhaus\nspin-orbit interaction (SOI) has been demonstrated, our work explores\ncavity-based qubit manipulation and coupling schemes for inversion-symmetric\ncrystals forming a planar HH QD. Choosing the exemplary material Germanium\n(Ge), we derive an effective cavity-mediated ground state spin coupling that\nharnesses the cubic Rashba SOI. In addition, we propose an optimal set of\nparameters which allows for Rabi frequencies in the MHz range, thus entering\nthe strong coupling regime of cavity quantum electrodynamics."
    },
    {
        "anchor": "Nonequilibrium self-energies, Ng approach and heat current of a\n  nanodevice for small bias voltage and temperature: Using non-equilibrium renormalized perturbation theory to second order in the\nrenormalized Coulomb repulsion, we calculate the lesser $\\Sigma^<$ and and\ngreater $\\Sigma^>$ self-energies of the impurity Anderson model, which\ndescribes the current through a quantum dot, in the general asymmetric case.\nWhile in general a numerical integration is required to evaluate the\nperturbative result, we derive an analytical approximation for small frequency\n$\\omega$, bias voltage $V$ and temperature $T$ which is exact to total second\norder in these quantities. The approximation is valid when the corresponding\nenergies $\\hbar \\omega$, $eV$ and $k_B T$ are small compared to $k_B T_K$,\nwhere $T_K$ is the Kondo temperature. The result of the numerical integration\nis compared with the analytical one and with Ng approximation, in which\n$\\Sigma^<$ and $\\Sigma^>$ are assumed proportional to the retarded self-energy\n$\\Sigma^r$ times an average Fermi function. While it fails at $T=0$ for\n$\\hbar|\\omega | \\lesssim eV$ we find that the Ng approximation is excellent for\n$k_B T > eV/2$ and improves for asymmetric coupling to the leads. Even at\n$T=0$, the effect of the Ng approximation on the total occupation at the dot is\nvery small. The dependence on $\\omega$ and $V$ are discussed in comparison with\na Ward identity that is fulfilled by the three approaches. We also calculate\nthe heat currents between the dot and any of the leads at finite bias voltage.\nOne of the heat currents changes sign with the applied bias voltage at finite\ntemperature.",
        "positive": "Elementary events of electron transfer in a voltage-driven quantum point\n  contact: We show that the statistics of electron transfer in a coherent quantum point\ncontact driven by an arbitrary time-dependent voltage is composed of elementary\nevents of two kinds: unidirectional one-electron transfers determining the\naverage current and bidirectional two-electron processes contributing to the\nnoise only. This result pertains at vanishing temperature while the extended\nKeldysh-Green's function formalism in use also enables the systematic\ncalculation of the higher-order current correlators at finite temperatures."
    },
    {
        "anchor": "Tunneling and nonlinear transport in a vertically coupled GaAs/AlGaAs\n  double quantum wire system: We report low-dimensional tunneling in an independently contacted vertically\ncoupled quantum wire system. This nanostructure is fabricated in a high quality\nGaAs/AlGaAs parallel double quantum well heterostructure. Using a novel flip\nchip technique to align top and bottom split gates to form low-dimensional\nconstrictions in each of the independently contacted quantum wells we\nexplicitly control the subband occupation of the individual wires. In addition\nto the expected 2D-2D tunneling results, we have found additional tunneling\nfeatures that are related to the 1D quantum wires.",
        "positive": "Shot noise in diffusive conductors: A quantitative analysis of\n  electron-phonon interaction effects: Using the 'drift-diffusion-Langevin' equation, we have quantitatively\nanalyzed the effects of electron energy relaxation via their interaction with\nphonons, generally in presence of electron-electron interaction, on shot noise\nin diffusive conductors. We have found that the noise power $ S_I(\\omega )$\n(both at low and high observation frequencies $\\omega $) drops to half of its\n'mesoscopic' value only at $\\beta \\gtrsim 100,$ where $\\beta $ is the ratio of\nthe sample length $L$ to the energy relaxation length $l_{% {\\rm ph}}$ (the\nlatter may be much larger then the dephasing length). It means in particular\nthat at low temperatures the shot noise may be substantial even when $L\\sim\n10^{-2}$ -- $10^{-1}$ cm, and the conductor is 'macroscopic' in any other\nrespect."
    },
    {
        "anchor": "Impact of a circularly polarized cavity photon field on the charge and\n  spin flow through an Aharonov-Casher ring: We explore the influence of a circularly polarized cavity photon field on the\ntransport properties of a finite-width ring, in which the electrons are subject\nto spin-orbit and Coulomb interaction. The quantum ring is embedded in an\nelectromagnetic cavity and described by ``exact'' numerical diagonalization. We\nstudy the case that the cavity photon field is circularly polarized and compare\nit to the linearly polarized case. The quantum device is moreover coupled to\nexternal, electrically biased leads. The time propagation in the transient\nregime is described by a non-Markovian generalized master equation. We find\nthat the spin polarization and spin photocurrents of the quantum ring are\nlargest for circularly polarized photon field and destructive Aharonov-Casher\n(AC) phase interference. The charge current suppression dip due to the\ndestructive AC phase becomes threefold under the circularly polarized photon\nfield as the interaction of the electrons' angular momentum and spin angular\nmomentum of light causes many-body level splitting leading to three many-body\nlevel crossing locations instead of one. The circular charge current inside the\nring, which is induced by the circularly polarized photon field, is found to be\nsuppressed in a much wider range around the destructive AC phase than the\nlead-device-lead charge current. The charge current can be directed through one\nof the two ring arms with the help of the circularly polarized photon field,\nbut is superimposed by vortices of smaller scale. Unlike the charge\nphotocurrent, the flow direction of the spin photocurrent is found to be\nindependent of the handedness of the circularly polarized photon field.",
        "positive": "Metal contacts in carbon nanotube field effect transistors: Beyond the\n  Schottky barrier paradigm: The observed performances of carbon nanotube field effect transistors are\nexamined using first-principles quantum transport calculations. We focus on the\nnature and role of the electrical contact of Au and Pd electrodes to open-ended\nsemiconducting nanotubes, allowing the chemical contact at the surface to fully\ndevelop through large-scale relaxation of the contacting atomic configuration.\nWe present the first direct numerical evidence of Pd contacts exhibiting\nperfect transparency for hole injection as opposed to that of Au contacts.\nTheir respective Schottky barrier heights, on the other hand, turn out to be\nfairly similar for realistic contact models. These findings are in general\nagreement with experimental data reported to date, and show that a Schottky\ncontact is not merely a passive ohmic contact but actively influences the\ndevice I-V behavior."
    },
    {
        "anchor": "Highly Superlinear Giant Terahertz Photoconductance in GaAs Quantum\n  Point Contacts in the Deep Tunneling Regime: A highly superlinear in radiation intensity photoconductance induced by\nterahertz laser radiation with moderate intensities has been observed in\nquantum point contacts made of GaAs quantum wells operating in the deep\ntunneling regime. For very low values of the normalized dark conductance\n$G_{\\rm dark}/ G_0 \\approx 10^{-6}$, with the conductance quantum $G_0=2e^2/h$,\nthe photoconductance scales exponentially with the radiation intensity, so that\nalready at $ 100 \\text{ mW}/\\text{cm}^2$ it increases by almost four orders of\nmagnitude. This effect is observed for a radiation electric field oriented\nalong the source drain direction. We provide model considerations of the effect\nand attribute it to the variation of the tunneling barrier height by the\nradiation field made possible by local diffraction effects. We also demonstrate\nthat cyclotron resonance due to an external magnetic field manifests itself in\nthe photoconductance completely suppressing the photoresponse.",
        "positive": "Microstructure and magnetic anisotropy of electrospun\n  Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$ nanofibers: A local probe study: Understanding the phenomena at the nanometer scale is of fundamental\nimportance for future improvements of desired properties of nanomaterials. We\nreport a detailed investigation of the microstructure and the resulting\nmagnetic anisotropy by magnetic, transmission electron microscope (TEM) and\nM\\\"ossbauer measurements of the electrospun Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$\nnanofibers. Our results show that the electrospun Cu$_{1-x}$Zn$_x$Fe$_2$O$_4$\nnanofibers exhibit nearly isotropic magnetic anisotropy. TEM measurements\nindicate that the nanofibers are composed of loosely connected and randomly\naligned nanograins. As revealed by the Henkel plot, these nanofibers and the\nnanograins within the nanofibers are dipolar coupled, which reduces the\neffective shape anisotropy leading to a nearly random configuration of the\nmagnetic moments inside the nanofibers, hence, the observed nearly isotropic\nmagnetic anisotropy can be easily understood."
    },
    {
        "anchor": "Cloning of Zero Modes in One-Dimensional Graphene Superlattices: One-dimensional (1D) graphene superlattices have been predicted to exhibit\nzero-energy modes a decade ago, but an experimental proof has remained missing.\nMotivated by a recent experiment that could possibly shed light on this, here\nwe perform quantum transport simulations for 1D graphene superlattices,\nconsidering electrostatically simulated potential profiles as realistic as\npossible. Combined with the analysis on the corresponding miniband structures,\nwe find that the zero modes generated by the 1D superlattice potential can be\nfurther cloned to higher energies, which are also accessible by tuning the\naverage density. Our multiterminal transverse magnetic focusing simulations\nfurther reveal the modulation-controllable ballistic miniband transport for 1D\ngraphene superlattices. A simple idea for creating a perfectly symmetric\nperiodic potential with strong modulation is proposed at the end of this work,\ngenerating well aligned zero modes up to 6 within a reasonable gate strength.",
        "positive": "Mesoscopic Charge Relaxation: We consider charge relaxation in the mesoscopic equivalent of an RC circuit.\nFor a single-channel, spin-polarized contact, self-consistent scattering theory\npredicts a universal charge relaxation resistance equal to half a resistance\nquantum independent of the transmission properties of the contact. This\nprediction is in good agreement with recent experimental results. We use a\ntunneling Hamiltonian formalism and show in Hartree-Fock approximation, that at\nzero temperature the charge relaxation resistance is universal even in the\npresence of Coulomb blockade effects. We explore departures from universality\nas a function of temperature and magnetic field."
    },
    {
        "anchor": "Thermally induced magnetic relaxation in square artificial spin ice: The properties of natural and artificial assemblies of interacting elements,\nranging from Quarks to Galaxies, are at the heart of Physics. The collective\nresponse and dynamics of such assemblies are dictated by the intrinsic\ndynamical properties of the building blocks, the nature of their interactions\nand topological constraints. Here we report on the relaxation dynamics of the\nmagnetization of artificial assemblies of mesoscopic spins. In our model\nnano-magnetic system - square artificial spin ice - we are able to control the\ngeometrical arrangement and interaction strength between the magnetically\ninteracting building blocks by means of nano-lithography. Using time resolved\nmagnetometry we show that the relaxation process can be described using the\nKohlrausch law and that the extracted temperature dependent relaxation times of\nthe assemblies follow the Vogel-Fulcher law. The results provide insight into\nthe relaxation dynamics of mesoscopic nano-magnetic model systems, with\nadjustable energy and time scales, and demonstrates that these can serve as an\nideal playground for the studies of collective dynamics and relaxations.",
        "positive": "Cascaded exciton emission of an individual strain-induced quantum dot: Single strain-induced quantum dots are isolated for optical experiments by\nselective removal of the inducing InP islands from the sample surface.\nUnpolarized emission of single, bi- and triexciton transitions are identified\nby power-dependent photoluminescence spectroscopy. Employing time-resolved\nexperiments performed at different excitation powers we find a pronounced shift\nof the rise and decay times of these different transitions as expected from\ncascaded emission. Good agreement is found for a rate equation model for a\nthree step cascade."
    },
    {
        "anchor": "Quantum Transport in an Array of Mesoscopic Rings: Effect of Interface\n  Geometry: Electron transport properties are investigated in an array of mesoscopic\nrings, where each ring is threaded by a magnetic flux $\\phi$. The array is\nattached to two semi-infinite one-dimensional metallic electrodes, namely,\nsource and drain, where the rings are considered either in series or in\nparallel configuration. A simple tight-binding model is used to describe the\nsystem and all the calculations are done based on the Green's function\nformalism. Here, we present conductance-energy and current-voltage\ncharacteristics in terms of ring-to-electrode coupling strength, ring-electrode\ninterface geometry and magnetic flux. Most interestingly it is observed that,\ntypical current amplitude in an array of mesoscopic rings in the series\nconfiguration is much larger compared to that in parallel configuration of\nthose rings. This feature is completely different from the classical analogy\nwhich may provide an important signature in designing nano-scale electronic\ndevices.",
        "positive": "Fractional charges in emergent neutral modes at the integer quantum Hall\n  effect: Charge fractionalization is a possible emergent excitation in a\nlow-dimensional system of interacting electrons. A known example is that of\nfractional charges in the fractional quantum Hall effect (FQHE) regime, which\nis a consequence of strong Coulomb interaction among the electrons whose\nkinetic energy is quenched by the strong magnetic field. Alternatively, the\ninteger QHE (IQHE), with electrons behaving largely as independent particles in\nLandau levels (LLs), lacks such fractionalization. However, for integer LLs\nfilling v=2, 3,... electrons propagate in copropagating adjacent chiral edge\nchannels, and thus interact and modify the non-interacting LLs. For example, at\nv=2, an electron injected selectively into a single non-interacting (bare) edge\nchannel is expected to decompose into a 'fast' mode and a 'slow' mode in the\nregion of interaction; each mode carry fractional charges shared between the\ntwo bare channels. Here, we report our sensitive shot noise measurement that\naffirms the presence of such fractionalization in v=2. Injecting partitioned\ncurrent into a 'hot' edge channel led to low frequency shot noise in the\nadjacent currentless 'cold' edge channel after it had been partitioned.\nControlling the partitioning of the hot and cold channels allowed a\ndetermination of the fractional charges in both channels as well as the\nchannels' velocity difference. This approach can be easily extended to study\ninteraction in two-dimensional systems with a topology dictating edge channels\ntransport."
    },
    {
        "anchor": "A Measurable Force driven by an Excitonic Condensate in DQWs: New free energy related signatures of the condensed excitons in Double\nQuantum Wells (DQW) are predicted and experiments are proposed to measure the\neffects. These signatures are related to the measurement of a conceptually new\nkind of force ($\\approx 10^{-9} N$) due to the condensate. This force, which\nmay be coined as the Exciton Condensate (EC)-force is attractive and\nreminiscent of the Casimir force between two perfect metallic plates, but also\ndistinctively different from it by its driving mechanism and dependence on the\nparameters of the condensate. The proposed experiments here are based on a\nrecent experimental work on a driven micromechanical oscillator with a proven\nhigh quality factor. The free energy related measurements are immune to the\ncommonly agreed drawbacks of the existing photoluminescence experiments. In\nthis regard, the proposed experiments are highly decisive about the EC.",
        "positive": "Quantum Tunneling Detection of Two-photon and Two-electron Processes: We analyze the operation of a quantum tunneling detector coupled to a\ncoherent conductor. We demonstrate that in a certain energy range the output of\nthe detector is determined by two-photon processes, two-electron processes and\nthe interference of the two. We show how the individual contributions of these\nprocesses can be resolved in experiments."
    },
    {
        "anchor": "Topological insulator ring with magnetic impurities: Topological insulators exhibit gapless edge or surface states that are\ntopologically protected by time-reversal symmetry. However, several promising\ncandidates for topologically insulating materials (such as Bi$_2$Se$_3$ and\nHgTe) contain spinful nuclei or other types of magnetic impurities that break\ntime-reversal symmetry. We investigate the consequences of such impurities\ncoupled to electronic edge states in a topological insulator quantum ring\nthreaded by a magnetic flux. We use spin conservation and additional symmetry\narguments to derive a universal formula for the spectrum of propagating edge\nmodes in terms of the amplitude of transmission through the impurity. Our\nresults apply for impurities of arbitrary spin. We show that there exists an\nenergy regime in which the spectrum becomes nearly independent of the flux and\nsignificant spectral gaps form. We further analyze the electron-impurity\nentanglement entropy, finding that maximal entanglement occurs near the gaps in\nthe spectrum. Our predictions can be investigated with quantum ring transport\ninterference experiments or through spin-resolved STM measurements, providing a\nnew approach to understand the role of impurities in topological insulator edge\ntransport.",
        "positive": "Linear Response of Zero-Resistance States: A two-dimensional electron system in the presence of a magnetic field and\nmicrowave irradiation can undergo a phase transition towards a zero-resistance\nstate. A widely used model predicts the zero-resistance state to be a domain\nstate, which responds to applied dc voltages or dc currents by slightly\nchanging the domain structure. Here we propose an alternative response\nscenario, according to which the domain pattern remains unchanged.\nSurprisingly, a fixed domain pattern does not destroy zero resistance, provided\nthat the resistance is direction independent. Otherwise, if the symmetry of the\ndomain pattern allows a direction dependence of the resistance, the domain\nstate can be dissipative. We give examples for both situations and simulate the\nresponse behavior numerically."
    },
    {
        "anchor": "Characterization of the Quantized Hall Insulator Phase in the Quantum\n  Critical Regime: The conductivity $\\sigma$ and resistivity $\\rho$ tensors of the disordered\nHofstadter model are mapped as functions of Fermi energy $E_F$ and temperature\n$T$ in the quantum critical regime of the plateau-insulator transition (PIT).\nThe finite-size errors are eliminated by using the non-commutative\nKubo-formula. The results reproduce all the key experimental characteristics of\nthis transition in Integer Quantum Hall (IQHE) systems. In particular, the\nQuantized Hall Insulator (QHI) phase is detected and analyzed. The presently\naccepted characterization of the QHI phase in the quantum critical regime,\nbased entirely on experimental data, is fully supported by our theoretical\ninvestigation.",
        "positive": "Unexpected Surface Implanted Layer in Static Random Access Memory\n  Devices Observed by Microwave Impedance Microscope: Real-space mapping of doping concentration in semiconductor devices is of\ngreat importance for the microelectronic industry. In this work, a scanning\nmicrowave impedance microscope (MIM) is employed to resolve the local\nconductivity distribution of a static random access memory (SRAM) sample. The\nMIM electronics can also be adjusted to the scanning capacitance microscopy\n(SCM) mode, allowing both measurements on the same region. Interestingly, while\nthe conventional SCM images match the nominal device structure, the MIM results\ndisplay certain unexpected features, which originate from a thin layer of the\ndopant ions penetrating through the protective layers during the heavy\nimplantation steps."
    },
    {
        "anchor": "An efficient tight-binding mode-space NEGF model enabling up to million\n  atoms III-V nanowire MOSFETs and TFETs simulations: We report the capability to simulate in a quantum mechanical tight-binding\n(TB) atomistic fashion NW devices featuring several hundred to millions of\natoms and diameter up to 18 nm. Such simulations go far beyond what is\ntypically affordable with today's supercomputers using a traditional real space\n(RS) TB Hamiltonian technique. We have employed an innovative TB mode space\n(MS) technique instead and demonstrate large speedup (up to 10,000x) while\nkeeping good accuracy (error smaller than 1 percent) compared to the RS NEGF\nmethod. Such technique and capability open new avenues to explore and\nunderstand the physics of nanoscale and mesoscopic devices dominated by quantum\neffects. In particular, our method addresses in an unprecedented way the\ntechnological relevant case of band-to-band tunneling (BTBT) in III-V nanowire\nMOSFETs and broken gap heterojunction tunnel-FETs (TFETs). We demonstrate an\naccurate match of simulated BTBT currents to experimental measurements in a\n[111] InAs NW having a 12 nm diameter and a 300 nm long channel. We apply the\npredictivity of our TB MS simulations and report an in-depth atomistic study of\nthe scaling potential of III-V GAA nanowire heterojunction n and pTFETs\nquantifying the benefits of this technology for low-power, low-voltage CMOS\napplication. At VDD = 0.3 V and IOFF = 50 pA/um, the on-current (Ion) and\nenergy-delay product (ETP) gain over a Si NW GAA MOSFET are 58x and 56x\nrespectively.",
        "positive": "Intrinsic and extrinsic photogalvanic effects in twisted bilayer\n  graphene: The chiral lattice structure of twisted bilayer graphene with D6 symmetry\nallows for intrinsic photogalvanic effects only at off-normal incidence, while\nadditional extrinsic effects are known to be induced by a substrate or a gate\npotential. In this work, we first compute the intrinsic effects and show they\nreverse sign at the magic angle, revealing a band inversion at the {\\Gamma}\npoint. We next consider different extrinsic effects, showing how they can be\nused to track the strengths of the substrate coupling or displacement field. We\nalso show that the approximate particle-hole symmetry implies stringent\nconstraints on the chemical potential dependence of all photocurrents. A\ndetailed comparison of intrinsic vs. extrinsic photocurrents therefore reveals\na wealth of information about the band structure and can also serve as a\nbenchmark to constrain the symmetry breaking patterns of correlated states."
    },
    {
        "anchor": "Phase-coherent heat circulator based on multi-terminal Josephson\n  junctions: We theoretically propose a phase-coherent thermal circulator based on\nballistic multiterminal Josephson junctions. The breaking of time-reversal\nsymmetry by either a magnetic flux or a superconducting phase bias allows heat\nto flow preferentially in one direction from one terminal to the next while\nheat flow in the opposite direction is suppressed. We find that our device can\nachieve a high circulation efficiency over a wide range of parameters and that\nits performance is robust with respect to the presence of disorder. We provide\nestimates for the expected heat currents for realistic samples.",
        "positive": "Charge Transport Through Open, Driven Two-Level Systems with Dissipation: We derive a Floquet-like formalism to calculate the stationary average\ncurrent through an AC driven double quantum dot in presence of dissipation. The\nmethod allows us to take into account arbitrary coupling strengths both of a\ntime-dependent field and a bosonic environment. We numerical evaluate a\ntruncation scheme and compare with analytical, perturbative results such as the\nTien-Gordon formula."
    },
    {
        "anchor": "Flat Bands in Buckled Graphene Superlattices: Interactions between stacked two-dimensional (2D) atomic crystals can\nradically change their properties, leading to essentially new materials in\nterms of the electronic structure. Here we show that monolayers placed on an\natomically flat substrate can be forced to undergo a buckling transition, which\nresults in periodically strained superlattices. By using scanning tunneling\nmicroscopy and spectroscopy and support from numerical simulations, we show\nthat such lateral superlattices in graphene lead to a periodically modulated\npseudo-magnetic field, which in turn creates a post-graphene material with flat\nelectronic bands. The described approach of controllable buckling of 2D\ncrystals offers a venue for creating other superlattice systems and, in\nparticular, for exploring interaction phenomena characteristic of flat bands.",
        "positive": "Parity meter for charge qubits: an efficient quantum entangler: We propose a realization of a charge parity meter based on two double quantum\ndots alongside a quantum point contact. Such a device is a specific example of\nthe general class of mesoscopic quadratic quantum measurement detectors\npreviously investigated by Mao et al. [Phys. Rev. Lett. 93, 056803 (2004)]. Our\nsetup accomplishes entangled state preparation by a current measurement alone,\nand allows the qubits to be effectively decoupled by pinching off the parity\nmeter. Two applications of the parity meter are discussed: the measurement of\nBell's inequality in charge qubits and the realization of a controlled NOT\ngate."
    },
    {
        "anchor": "Observation of Spin-Orbit Berry's Phase in Magnetoresistance of a\n  Two-Dimensional Hole Anti-dot System: We report observation of spin-orbit Berry's phase in the Aharonov-Bohm (AB)\ntype oscillation of weak field magnetoresistance in an anti-dot lattice (ADL)\nof a two-dimensional hole system. An AB-type oscillation is superposed on the\ncommensurability peak, and the main peak in the Fourier transform is clearly\nsplit up due to variation in Berry's phase originating from the spin-orbit\ninteraction. A simulation considering Berry's phase and the phase arising from\nthe spin-orbit shift in the momentum space shows qualitative agreement with the\nexperiment.",
        "positive": "Tunable Magnetism and Half-Metallicity in Hole-doped Monolayer GaSe: We find, through first-principles calculations, that hole doping induces a\nferromagnetic phase transition in monolayer GaSe. Upon increasing hole density,\nthe average spin magnetic moment per carrier increases and reaches a plateau\nnear 1.0 $\\mu_{\\rm{B}}$/carrier in a range of $3\\times\n10^{13}$/cm$^{2}$-$1\\times 10^{14}$/cm$^{2}$ with the system in a half-metal\nstate before the moment starts to descend abruptly. The predicted magnetism\noriginates from an exchange splitting of electronic states at the top of the\nvalence band where the density of states exhibits a sharp van Hove singularity\nin this quasi-two-dimensional system."
    },
    {
        "anchor": "Magnetic measurements on micron-size samples under high pressure using\n  designed NV centers: Pressure is a unique tool to tune the interplay between structural,\nelectronic and magnetic interactions. It leads to remarkable properties of\nmaterials such as recent temperature records in superconductivity. Advanced\nmagnetic measurements under very high pressure in the Diamond Anvil Cell (DAC)\nuse synchrotron approaches but these are lacking a formal link to the\nmacroscopic magnetic properties. We report an alternative method consisting in\noptical magnetometry based on nitrogen-vacancy (NV) centers created at the\nsurface of a diamond anvil. We illustrate the method by two measurements\nrealized at room and low temperature respectively: the pressure evolution of\nthe magnetization of an iron bead up to 30 GPa showing the iron ferromagnetic\ncollapse and the detection of the superconducting transition of MgB2 at 7 GPa.",
        "positive": "DNA-based Self-Assembly of Chiral Plasmonic Nanostructures with Tailored\n  Optical Response: Surface plasmon resonances generated in metallic nanostructures can be\nutilized to tailor electromagnetic fields. The precise spatial arrangement of\nsuch structures can result in surprising optical properties that are not found\nin any naturally occurring material. Here, the designed activity emerges from\ncollective effects of singular components equipped with limited individual\nfunctionality. Top-down fabrication of plasmonic materials with a predesigned\noptical response in the visible range by conventional lithographic methods has\nremained challenging due to their limited resolution, the complexity of\nscaling, and the difficulty to extend these techniques to three-dimensional\narchitectures. Molecular self-assembly provides an alternative route to create\nsuch materials which is not bound by the above limitations. We demonstrate how\nthe DNA origami method can be used to produce plasmonic materials with a\ntailored optical response at visible wavelengths. Harnessing the assembly power\nof 3D DNA origami, we arranged metal nanoparticles with a spatial accuracy of 2\nnm into nanoscale helices. The helical structures assemble in solution in a\nmassively parallel fashion and with near quantitative yields. As a designed\noptical response, we generated giant circular dichroism and optical rotary\ndispersion in the visible range that originates from the collective\nplasmon-plasmon interactions within the nanohelices. We also show that the\noptical response can be tuned through the visible spectrum by changing the\ncomposition of the metal nanoparticles. The observed effects are independent of\nthe direction of the incident light and can be switched by design between left-\nand right-handed orientation. Our work demonstrates the production of complex\nbulk materials from precisely designed nanoscopic assemblies and highlights the\npotential of DNA self-assembly for the fabrication of plasmonic nanostructures."
    },
    {
        "anchor": "The Miniband Alignment Field-Effect Transistor: a superlattice-based\n  steep-slope nanowire FET: This work investigates energy filtering in nanowires, where pass and\nstopbands are obtained by including superlattices in the wire. When a pair of\nsuch superlattices is placed in series, each being controlled by a gate, it can\nact as a transistor where the (mis-)alignment of its minibands turns the device\non (off). It is shown that, in the ballistic current-regime, the transition\nbetween the on and off state occurs in a narrow gate-bias range, giving rise to\nsub-60 mV per decade switching behavior.",
        "positive": "Local and non-local two-electron tunneling processes in a Cooper pair\n  splitter: We measure the tunneling rates and coupling coefficients for local Andreev,\nnon-local Andreev and elastic cotunneling processes. The non-local Andreev\nprocess, giving rise to Cooper pair splitting, exhibits the same coupling\ncoefficient as the elastic co-tunneling whereas the local Andreev process is\nmore than two orders of magnitude stronger than the corresponding non-local\none. Theory estimates describe the findings and explain the large difference in\nthe non-local and local coupling arising from competition between electron\ndiffusion in the superconductor and tunnel junction transparency."
    },
    {
        "anchor": "Valley splitting of Si/SiGe heterostructures in tilted magnetic fields: We have investigated the valley splitting of two-dimensional electrons in\nhigh quality Si/Si$_{1-x}$Ge$_x$ heterostructures under tilted magnetic fields.\nFor all the samples in our study, the valley splitting at filling factor\n$\\nu=3$ ($\\Delta_3$) is significantly different before and after the\ncoincidence angle, at which energy levels cross at the Fermi level. On both\nsides of the coincidence, a linear density dependence of $\\Delta_3$ on the\nelectron density was observed, while the slope of these two configurations\ndiffers by more than a factor of two. We argue that screening of the Coulomb\ninteraction from the low-lying filled levels, which also explains the observed\nspin-dependent resistivity, is responsible for the large difference of\n$\\Delta_3$ before and after the coincidence.",
        "positive": "Spin current generation by helical states in a quasi-one-dimensional\n  system: Time-reversal symmetry and rotational invariance in spin space characterize\nusual non-magnetic conductors. These symmetries give rise, at least, to\nfour-fold degenerate multiplets which, by definition, exhibit a null total\nspin-momentum helicity. Thus, preventing a net spin transport. A proper choice\nof geometry along with the intrinsic symmetry of the Bychkov-Rashba spin-orbit\ninteraction can be exploited to effectively reduce these two spin-related\nsymmetries to the timereversal one. It is shown that, in an ideal geometry, a\nquantum dot with contacts having a specific geometry exhibit a single pair of\nhelical propagating states which makes this system ideal for pure spin current\ngeneration. The strong quantization of the quantum dot's level structure would\nmake this mechanism robust against temperature effects."
    },
    {
        "anchor": "Magnon-phonon interactions in magnon spintronics: Nowadays, the interaction between phonon and magnon subsystems of a magnetic\nmedium is a hot topic of research. The complexity of phonon and magnon spectra,\nthe existence of both bulk and surface modes, the quantization effects, and the\ndependence of magnon properties on applied magnetic field, make this field very\ncomplex and intriguing. Moreover, the recent advances in the fields of\nspin-caloritronics and magnon spintronics as well as the observation of the\nspin Seebeck effect (SSE) in magnetic insulators points on the crucial role of\nmagnons in spin-caloric transport processes. In this review, we collect the\nvariety of different studies in which magnon-phonon interaction play important\nrole. The scope of the paper covers the wide range of phenomena starting from\nthe interaction of the coherent magnons with surface acoustic wave and\nfinishing with the formation of magnon supercurrents in the thermal gradients.",
        "positive": "Huge anisotropic magneto-resistance in iridium atomic chains: We analyze in this article the magneto-resistance ratio of finite and\ninfinite iridium and platinum chains. Our calculations, that are based on a\ncombination of non equilibrium Green function techniques and density functional\ntheory, include a fully self-consistent treatment of non-collinear magnetism\nand of the spin-orbit interaction. They indicate that, in addition to having an\nextremely large magnetic anisotropy that may overcome the super-paramagnetic\nlimit, infinite and also realistic finite-length iridium chains show sizeable\nanisotropic magnetoresistance ratios. We therefore propose iridium\nnanostructures as promising candidates for nanospintronics logic devices."
    },
    {
        "anchor": "Effect of the nanowire diameter on the linearity of the response of\n  GaN-based heterostructured nanowire photodetectors: Nanowire photodetectors are investigated because of their compatibility with\nflexible electronics, or for the implementation of on-chip optical\ninterconnects. Such devices are characterized by ultrahigh photocurrent gain,\nbut their photoresponse scales sublinearly with the optical power. Here, we\npresent a study of single-nanowire photodetectors displaying a linear response\nto ultraviolet illumination. Their structure consists of a GaN nanowire\nincorporating an AlN/GaN/AlN heterostructure, which generates an internal\nelectric field. The activity of the heterostructure is confirmed by the\nrectifying behavior of the current-voltage characteristics in the dark, as well\nas by the asymmetry of the photoresponse in magnitude and linearity. Under\nreverse bias (negative bias on the GaN cap segment), the detectors behave\nlinearly with the impinging optical power when the nanowire diameter is below a\ncertain threshold ($\\approx$ 80 nm), which corresponds to the total depletion\nof the nanowire stem due to the Fermi level pinning at the sidewalls. In the\ncase of nanowires that are only partially depleted, their nonlinearity is\nexplained by a nonlinear variation of the diameter of their central conducting\nchannel under illumination.",
        "positive": "Mapping of strained graphene into one-dimensional Hamiltonians:\n  quasicrystals and modulated crystals: The electronic properties of graphene under any arbitrary uniaxial strain\nfield are obtained by an exact mapping of the corresponding tight-binding\nHamiltonian into an effective one-dimensional modulated chain. For a periodic\nmodulation, the system displays a rich behavior, including quasicrystals and\nmodulated crystals with a complex spectrum, gaps at the Fermi energy and\ninteresting localization properties. These features are explained by the\nincommensurate or commensurate nature of the potential, which leads to a dense\nfilling of the reciprocal space in the former case. Thus, the usual\nperturbation theory approach breaks down in some cases, as is proved by\nanalyzing a special momentum that uncouples the model into dimers."
    },
    {
        "anchor": "Comment on ``Time-dependent current-density functional theory for\n  generalized open quantum systems\" by J. Yuen-Zhou, C. Rodriiguez-Rosario and\n  A. Aspuru-Guzik: We comment on a recent paper by Yuen-Zhou et al. [ Phys. Chem. Chem. Phys.\n2009, 11, 4509 ] which extends some of the results of Time-Dependent Current\nDensity Functional Theory applied to open quantum systems. Besides pointing out\nsome incorrect statements in the theorems, we show that in the proof of the\nmain result of the paper an arbitrary condition is introduced. Moreover, we\nargue that, since this condition has not a physical origin, one can find two\nsystems with different vector potentials that lead to the same dynamics of the\nphysical quantities of interest, the current and particle densities.",
        "positive": "Mirror skin effect and its electric circuit simulation: We analyze impacts of crystalline symmetry on the non-Hermitian skin effects.\nFocusing on mirror symmetry, we propose a novel type of skin effects, a mirror\nskin effect, which results in significant dependence of energy spectrum on the\nboundary condition only for the mirror invariant line in the two-dimensional\nBrillouin zone. This effect arises from the topological properties\ncharacterized by a mirror winding number. We further reveal that the mirror\nskin effect can be observed for an electric circuit composed of negative\nimpedance converters with current inversion where switching the boundary\ncondition significantly changes the admittance eigenvalues only along the\nmirror invariant lines. Furthermore, we demonstrate that extensive localization\nof the eigenstates for each mirror sector result in an anomalous voltage\nresponse."
    },
    {
        "anchor": "Discrete tunneling in granulated substances and other similar mediums: Work is devoted to physics of current transport in a wide class of the\nhetero-phase granulated mediums and similar systems with set of metal or\nsemi-conductor granules, quantum dots or potential wells in which the exit from\nCoulomb blockade tunneling regime can be not observable because of irreversible\nbreakdown and destruction of structure of medium. Such systems also concern and\nthe condensed mediums with short distanced atoms of transition elements. In\narticle for small and average electric fields the analytical decision of a\nstationary problem of discrete electronic transport through a chain of as much\nas big number of metal granules in area Coulomb tunneling blockade is\nperformed. It is deduced the exponential law of growth of a current with\nelectric field in such granulated systems. The characteristic feature of\ndiscrete tunneling in such medium is the volt-ampere characteristic type I\nexp(V/(N+1)kT) with great value N>> 1. Examples of application of the theory\nfor explanation of current transport in porous silicon, synthesised by ionic\nimplantation of nitrogen in silicon layers of nitride of silicon or glass like\namorphous semiconductors are resulted.",
        "positive": "Controllable anisotropic exchange coupling between spin qubits in\n  quantum dots: The exchange coupling between quantum dot spin qubits is isotropic, which\nrestricts the types of quantum gates that can be formed. Here, we propose a\nmethod for controlling anisotropic interactions between spins arranged in a bus\ngeometry. The symmetry is broken by an external magnetic field, resulting in\nXXZ-type interactions that can efficiently generate Greenberger-Horne-Zeilinger\n(GHZ) states or universal gate sets for exchange-only quantum computing.\nAnalysis of the bus ground state provides a link between quantum critical\nphenomena and the communication capacity."
    },
    {
        "anchor": "Generalized Wiedemann-Franz law in a two-site charge Kondo circuit:\n  Lorenz ratio as a manifestation of the orthogonality catastrophe: We show that the transport integrals of the two-site charge Kondo circuits\nconnecting various multi-channel Kondo simulators satisfy the generalized\nWiedemann-Franz law with the universal Lorenz ratios all greater than one. The\nmagic Lorenz ratios are directly related to the Anderson's orthogonality\ncatastrophe in quantum simulators providing some additional universal measure\nfor the strong electron-electron correlations. We present a full fledged theory\nfor the magic Lorenz ratios and discuss possible routes for the experimental\nverifications of the theory.",
        "positive": "Collective interlayer pairing and pair superfluidity in vertically\n  stacked layers of dipolar excitons: Layered bosonic dipolar fluids have been suggested to host a condensate of\ninterlayer molecular bound states. However, its experimental observation has\nremained elusive. Motivated by two recent experimental works [Hubert et al.,\nPhys. Rev. X 9, 021026 (2019) and D. J. Choksy et al., Phys. Rev. B 103 045126\n(2021)], we theoretically study, using numerically exact quantum Monte Carlo\ncalculations, the experimental signatures of collective interlayer pairing in\nvertically stacked indirect exciton (IX) layers. We find that IX energy shifts\nassociated with each layer evolve non trivially as a function of density\nimbalance following a nonmonotonic trend with a jump discontinuity at density\nbalance, identified with the interlayer IX molecule gap. This behavior\ndiscriminates between the superfluidity of interlayer bound pairs and\nindependent dipole condensation in distinct layers. Considering finite\ntemperature and finite density imbalance conditions, we find a cascade of\nBerezinskii--Kosterlitz--Thouless (BKT) transitions, initially into a pair\nsuperfluid and only then, at lower temperatures, into complete superfluidity of\nboth layers. Our results may provide a theoretical interpretation of existing\nexperimental observations in GaAs double quantum well (DQW) bilayer structures.\nFurthermore, to optimize the visibility of pairing dynamics in future studies,\nwe present an analysis suggesting realistic experimental settings in GaAs and\ntransition metal dichalcogenide (TMD) bilayer DQW heterostructures where\ncollective interlayer pairing and pair superfluidity can be clearly observed."
    },
    {
        "anchor": "Spectral and polarization effects in deterministically nonperiodic\n  multilayers containing optically anisotropic and gyrotropic materials: Influence of material anisotropy and gyrotropy on optical properties of\nfractal multilayer nanostructures is theoretically investigated. Gyrotropy is\nfound to uniformly rotate the output polarization for bi-isotropic multilayers\nof arbitrary geometrical structure without any changes in transmission spectra.\nWhen introduced in a polarization splitter based on a birefringent fractal\nmultilayer, isotropic gyrotropy is found to resonantly alter output\npolarizations without shifting of transmission peak frequencies. The design of\nfrequency-selective absorptionless polarizers for polarization-sensitive\nintegrated optics is outlined.",
        "positive": "Observation of the frozen charge of a Kondo resonance: The ability to control electronic states at the nanoscale has contributed to\nour modern understanding of condensed matter. In particular, quantum dot\ncircuits represent model systems for the study of strong electronic\ncorrelations, epitomized by the Kondo effect. Here, we show that circuit\nQuantum Electrodynamics architectures can be used to study the internal degrees\nof freedom of such a many-body phenomenon. We couple a quantum dot to a high\nfinesse microwave cavity to measure with an unprecedented sensitivity the dot\nelectronic compressibility i.e. the ability of the dot to accommodate charges.\nBecause it corresponds solely to the charge response of the electronic system,\nthis quantity is not equivalent to the conductance which involves in general\nother degrees of freedom such as spin. By performing dual\nconductance/compressibility measurements in the Kondo regime, we uncover\ndirectly the charge dynamics of this peculiar mechanism of electron transfer.\nStrikingly, the Kondo resonance, visible in transport measurements, is\ntransparent to microwave photons trapped in the high finesse cavity. This\nreveals that, in such a many body resonance, finite conduction is achieved from\na charge frozen by Coulomb interaction. This previously elusive freezing of\ncharge dynamics is in stark contrast with the physics of a free electron gas.\nOur setup highlights the power of circuit quantum electrodynamics architectures\nto study condensed matter problems. The tools of cavity quantum electrodynamics\ncould be used in other types of mesoscopic circuits with many-body correlations\nand bring a promising platform to perform quantum simulation of fermion-boson\nproblems."
    },
    {
        "anchor": "Planar Hall-effect, Anomalous planar Hall-effect, and Magnetic\n  Field-Induced Phase Transitions in TaAs: We evaluate the topological character of TaAs through a detailed study of the\nangular, magnetic-field and temperature dependence of its magnetoresistivity\nand Hall-effect(s), and of its bulk electronic structure through quantum\noscillatory phenomena. At low temperatures, and for fields perpendicular to the\nelectrical current, we extract an extremely large Hall angle $\\Theta_H$ at\nhigher fields, that is $\\Theta_H \\sim 82.5^{\\circ}$, implying a very pronounced\nHall signal superimposed into its magnetoresistivity. For magnetic fields and\nelectrical currents perpendicular to the \\emph{c}-axis we observe a very\npronounced planar Hall-effect, when the magnetic field is rotated within the\nbasal plane. This effect is observed even at higher temperatures, i.e. as high\nas $T = 100$ K, and predicted recently to result from the chiral anomaly among\nWeyl points. Superimposed onto this planar Hall, which is an even function of\nthe field, we observe an anomalous planar Hall-signal akin to the one reported\nfor that is an odd function of the field. Below 100 K, negative longitudinal\nmagnetoresistivity (LMR), initially ascribed to the chiral anomaly and\nsubsequently to current inhomogeneities, is observed in samples having\ndifferent geometries and contact configurations, once the large Hall signal is\nsubtracted. Our measurements reveal a phase transition upon approaching the\nquantum limit that leads to the reconstruction of the FS and to the concomitant\nsuppression of the negative LMR indicating that it is intrinsically associated\nwith the Weyl dispersion at the Fermi level. For fields along the \\emph{a}-axis\nit also leads to a pronounced hysteresis pointing to a field-induced electronic\nphase-transition. This collection of unconventional tranport observations\npoints to the prominent role played by the axial anomaly among Weyl nodes.",
        "positive": "Non-collinear first-principles studies of the spin-electric coupling in\n  frustrated triangular molecular magnets: Frustrated triangular molecular magnets (MMs) with anti-ferromagnetic ground\nstates (GS) are an important class of magnetic systems with potential\napplications in quantum information processing. The two-fold degenerate GS of\nthese molecules, characterized by spin chirality, can be utilized to encode\nqubits for quantum computing. Furthermore, because of the lack of inversion\nsymmetry in these molecules, an electric field couples directly states of\nopposite chirality, allowing a very efficient and fast control of the qubits.\nIn this work we present a theoretical method to calculate the spin-electric\ncoupling for triangular MMs with effective {\\it local} spins $s$ larger than\n1/2, which is amenable to a first-principles implementation based on density\nfunctional theory (DFT). In contrast to MMs where the net magnetization at the\nmagnetic atoms is $\\mu_{\\rm B}/2$ ($\\mu_{\\rm B} $ is the Bohr magneton), the\nDFT treatment of frustrated triangular MMs with larger local magnetizations\nrequires a fully non-collinear approach, which we have implemented in the\nNRLMOL DFT code. As an example, we have used these methods to evaluate the\nspin-electric coupling for a spin $s = 5/2$ $\\{\\mathrm{Fe_3}\\}$ triangular MM,\nwhere this effect has been observed experimentally for the first time quite\nrecently. Our theoretical and computational methods will help elucidate and\nfurther guide ongoing experimental work in the field of quantum molecular\nspintronics."
    },
    {
        "anchor": "Collective modes and the far-infrared absorption of the two-dimensional\n  electron gas in a periodic quantizing magnetic field: We investigate the far-infrared (FIR) absorption of a two-dimensional\nelectron gas in a periodically modulated quantizing magnetic field. The\nmagnetic field varies along only one spatial direction and the external\ntime-dependent electric field is linearly polarized along that axis. The mutual\nCoulomb interaction of the electrons is treated self-consistently in the ground\nstate and in the absorption calculation within the Hartree approximation. The\neffects of the magnetic material on top of the heterostructure as a grating\ncoupler is included in the time-dependent incident FIR electric field. We show\nthat similar to an electric modulation, the absorption can be directly\ncorrelated to the underlying electronic energy bands. In addition, the magnetic\nmodulation leads to absorption spectra with a richer structure due to the quite\ndifferent static response of the electron density to the modulation.",
        "positive": "High Magnetic Field Microwave Conductivity of 2D Electrons in an Array\n  of Antidots: We measure the high magnetic field ($B$) microwave conductivity,\nRe$\\sigma_{xx}$, of a high mobility 2D electron system containing an antidot\narray. Re$\\sigma_{xx}$ vs frequency ($f$) increases strongly in the regime of\nthe fractional quantum Hall effect series, with Landau filling $1/3<\\nu<2/3$.\nAt microwave $f$, Re$\\sigma_{xx}$ vs $B$ exhibits a broad peak centered around\n$\\nu=1/2$. On the peak, the 10 GHz Re$\\sigma_{xx}$ can exceed its dc-limit\nvalue by a factor of 5. This enhanced microwave conductivity is unobservable\nfor temperature $T \\gtrsim 0.5$ K, and grows more pronounced as $T$ is\ndecreased. The effect may be due to excitations supported by the antidot edges,\nbut different from the well-known edge magnetoplasmons."
    },
    {
        "anchor": "Magnetic field mediated conductance oscillation in graphene p-n\n  junctions: The electronic transport of graphene p-n junctions under perpendicular\nmagnetic field is investigated in theory. Under low magnetic field, the\ntransport is determined by the resonant tunneling of Landau levels and\nconductance versus magnetic field shows a Shubnikov-de Haas oscillation. At\nhigher magnetic field, the p-n junction subjected to the quasi-classical regime\nand the formation of snake states results in periodical backscattering and\ntransmission as magnetic field varies. The conductance oscillation pattern is\nmediated both by magnetic field and the carrier concentration on bipolar\nregions. For medium magnetic field between above two regimes, the combined\ncontributions of resonant tunneling, snake states oscillation and Aharanov-Bohm\ninterference induce irregular oscillation of conductance. At very high magnetic\nfield, the system is subjected to quantum Hall regime. Under disorder, the\nquantum tunneling at low magnetic field is slightly affected and the\noscillation of snake states at higher magnetic field is suppressed. In the\nquantum Hall regime, the conductance is a constant as predicted by the mixture\nrule.",
        "positive": "Demonstrating the decoupling regime of the electron-phonon interaction\n  in a quantum dot using chirped optical excitation: Excitation of a semiconductor quantum dot with a chirped laser pulse allows\nexcitons to be created by rapid adiabatic passage. In quantum dots this process\ncan be greatly hindered by the coupling to phonons. Here we add a high chirp\nrate to ultra-short laser pulses and use these pulses to excite a single\nquantum dot. We demonstrate that we enter a regime where the exciton-phonon\ncoupling is effective for small pulse areas, while for higher pulse areas a\ndecoupling of the exciton from the phonons occurs. We thus discover a\nreappearance of rapid adiabatic passage, in analogy to the predicted\nreappearance of Rabi rotations at high pulse areas. The measured results are in\ngood agreement with theoretical calculations."
    },
    {
        "anchor": "Theory of spin qubits in nanostructures: We review recent advances on the theory of spin qubits in nanostructures. We\nfocus on four selected topics. First, we show how to form spin qubits in the\nnew and promising material graphene. Afterwards, we discuss spin relaxation and\ndecoherence in quantum dots. In particular, we demonstrate how charge\nfluctations in the surrounding environment cause spin decay via spin--orbit\ncoupling. We then turn to a brief overview of how one can use electron-dipole\nspin resonance (EDSR) to perform single spin rotations in quantum dots using an\noscillating electric field. The final topic we cover is the spin-spin coupling\nvia spin-orbit interaction which is an alternative to the usual spin-spin\ncoupling via the Heisenberg exchange interaction.",
        "positive": "3D nano-bridge-based SQUID susceptometers for scanning magnetic imaging\n  of quantum materials: We designed and fabricated a new type of superconducting quantum interference\ndevice (SQUID) susceptometers for magnetic imaging of quantum materials. The\n2-junction SQUID sensors employ 3D Nb nano-bridges fabricated using electron\nbeam lithography. The two counter-wound balanced pickup loops of the SQUID\nenable gradiometric measurement and they are surrounded by a one-turn field\ncoil for susceptibility measurements. The smallest pickup loop of the SQUIDs\nwere 1 ${\\mu}m$ in diameter and the flux noise was around 1\n$\\mu{\\Phi}_0/\\sqrt{Hz}$ at 100 Hz. We demonstrate scanning magnetometry,\nsusceptometry and current magnetometry on some test samples using these\nnano-SQUIDs."
    },
    {
        "anchor": "Cold-electron bolometer, as a 1 cm wavelength photon counter: We investigate theoretically the possibility of using the cold-electron\nbolometer (CEB) as a counter for 1 cm wavelength (30 GHz) photons. To reduce\nthe flux of photons from the environment, which interact with the detector, the\nbath temperature is assumed to be below 50 mK. At such temperatures, the time\ninterval between two subsequent photons of 30 GHz that hit the detector is more\nthan 100 hours, on average, for a frequency window of 1 MHz. Such temperatures\nallow the observation of the physically significant photons produced in rare\nevents, like the axions conversion (or Primakoff conversion) in magnetic field.\nWe present the general formalism for the detector's response and noise,\ntogether with numerical calculations for proper experimental setups. We observe\nthat the current-biased regime is favorable, due to lower noise, and allows for\nthe photons counting at least below 50 mK. For the experimental setups\ninvestigated here, the voltage-biased CEBs may also work as photons counters,\nbut with less accuracy and eventually at bath temperatures below 40 mK. The\nvoltage-biased setups also require smaller volumes of the normal metal island\nof the detector.",
        "positive": "Variable range of the RKKY interaction in edged graphene: The indirect exchange interaction is one of the key factors in determining\nthe overall alignment of magnetic impurities embedded in metallic host\nmaterials. In this work we examine the range of this interaction in\nmagnetically-doped graphene systems in the presence of armchair edges using a\ncombination of analytical and numerical Green function (GF) approaches. We\nconsider both a semi-infinite sheet of graphene with a single armchair edge,\nand also quasi-one-dimensional armchair edged graphene nanoribbons (GNRs).\nWhile we find signals of the bulk decay rate in semi-infinite graphene and\nsignals of the expected one-dimensional decay rate in GNRs, we also find an\nunusually rapid decay for certain instances in both, which manifests itself\nwhenever the impurities are located at sites which are a multiple of three\natoms from the edge. This decay behavior emerges from both the analytic and\nnumerical calculations, and the result for semi-infinite graphene can be\ninterpreted as an intermediate case between ribbon and bulk systems."
    },
    {
        "anchor": "Multi-gap topology of the Wilson loop operator in mirror symmetric\n  insulators: We study the multi-gap topology of the periodic spectra of Wilson loop\noperators (WLOs) in mirror symmetric insulators. We develop two topological\ninvariants each associated with a mirror-invariant gap in the Wilson loop\nspectrum. We propose that both topological invariants in combination determine\nthe general higher-order bulk-boundary correspondence in 2D mirror symmetric,\nboundary-obstructed topological insulators. Finally, we demonstrate that these\nnew multi-gap topological invariants apply to anomalous cases beyond those\ncaptured by the nested Wilson loop, and we subsequently develop an\nunderstanding of the correlation between WLOs along two orthogonal directions.",
        "positive": "Plasmon modes in the magnetically doped Single Layer and Multilayers of\n  Helical Metals: We study the plasmon excitations and the electromagnetic response of the\nmagnetically doped single layer and multilayer of ``helical metals'', which\nemerge at the surfaces of topological insulators. For the single layer case, we\nfind a ``spin-plasmon'' mode with the rotating spin texture due to the\ncombination of the spin-momentum locking of ``helical metals'' and the Hall\nresponse from magnetization. For the multilayers case, we investigate the\nelectromagnetic response due to the plasmon excitations, including the Faraday\nrotation for the light propagating normal to the helical metal layers and an\nadditional optical mode with the frequency within the conventional plasmon gap\nfor the light propagating along the helical metal layers."
    },
    {
        "anchor": "Defect induced negative magnetoresistance and surface state immunity in\n  topological insulator BiSbTeSe2: Absence of backscattering and occurrence of weak anti-localization are two\ncharacteristic features of topological insulators. We find that the\nintroduction of defects results in the appearance of a negative contribution to\nmagnetoresistance in the topological insulator BiSbTeSe2, at temperatures below\n50 K. Our analysis shows that the negative magnetoresistance originates from an\nincrease in the density of defect states created by introduction of disorder,\nwhich leaves the surface states unaffected. We find a decrease in the magnitude\nof the negative magnetoresistance contribution with increasing temperature and\na robustness of the topological surface states to external disorder.",
        "positive": "Boron Nitride Nanosheet Veiled Gold Nanoparticles for Surface Enhanced\n  Raman Scattering: Atomically thin boron nitride (BN) nanosheets have many properties desirable\nfor surface enhanced Raman spectroscopy (SERS). BN nanosheets have a strong\nsurface adsorption capability towards airborne hydrocarbon and aromatic\nmolecules. For maximized adsorption area and hence SERS sensitivity, atomically\nthin BN nanosheet covered gold nanoparticles have been prepared for the first\ntime. When placed on top of metal nanoparticles, atomically thin BN nanosheets\nclosely follow their contours so that the plasmonic hot spots are retained.\nElectrically insulating BN nanosheets also act as a barrier layer to eliminate\nmetal-induced disturbance in SERS. Moreover, the SERS substrates veiled by BN\nnanosheets show an outstanding reusability in the long term. As the result, the\nsensitivity, reproducibility and reusability of SERS substrates can be greatly\nimproved. We also demonstrate that large BN nanosheets produced by chemical\nvapor deposition can be used to scale up the proposed SERS substrate for\npractical application."
    },
    {
        "anchor": "Transport through an Anderson impurity: Current ringing, non-linear\n  magnetization and a direct comparison of continuous-time quantum Monte Carlo\n  and hierarchical quantum master equations: We give a detailed comparison of the hierarchical quantum master equation\n(HQME) method to a continuous-time quantum Monte Carlo (CT-QMC) approach,\nassessing the usability of these numerically exact schemes as impurity solvers\nin practical nonequilibrium calculations. We review the main characteristics of\nthe methods and discuss the scaling of the associated numerical effort. We\nsubstantiate our discussion with explicit numerical results for the\nnonequilibrium transport properties of a single-site Anderson impurity. The\nnumerical effort of the HQME scheme scales linearly with the simulation time\nbut increases (at worst exponentially) with decreasing temperature. In\ncontrast, CT-QMC is less restricted by temperature at short times, but in\ngeneral the cost of going to longer times is also exponential. After\nestablishing the numerical exactness of the HQME scheme, we use it to elucidate\nthe influence of different ways to induce transport through the impurity on the\ninitial dynamics, discuss the phenomenon of coherent current oscillations,\nknown as current ringing, and explain the non-monotonic temperature dependence\nof the steady-state magnetization as a result of competing broadening effects.\nWe also elucidate the pronounced non-linear magnetization dynamics, which\nappears on intermediate time scales in the presence of an asymmetric coupling\nto the electrodes.",
        "positive": "Photocurrent characteristics of individual GeSe2 nanobelt with Schottky\n  effects: Single crystal GeSe2 nanobelts (NBs) were successfully grown using chemical\nvapor deposition techniques. The morphology and structure of the nanostructures\nwere characterized using scanning electron microscopy, transmission electron\nmicroscopy, X-ray diffractometry, and Raman spectroscopy. Electronic transport\nproperties, photoconductive characteristics, and temperature-dependent\nelectronic characteristics were examined on devices made of individual GeSe2\nnanobelt. Localized photoconductivity study shows that the large photoresponse\nof the device primarily occurs at the metal-NB contact regions. In addition,\nthe electrically Schottky nature of nanobelt-Au contact and p-type conductivity\nnature of GeSe2 nanobelt are extracted from the current-voltage characteristics\nand spatially resolved photocurrent measurements. The high sensitivity and\nquick photoresponse in the visible wavelength range indicate potential\napplications of individual GeSe2 nanobelt devices in realizing optoelectronic\nswitches."
    },
    {
        "anchor": "Doppler shift picture of the Dzyaloshinskii--Moriya interaction: We present a physical picture for the emergence of the Dzyaloshinskii--Moriya\n(DM) interaction based on the idea of the Doppler shift by an intrinsic spin\ncurrent induced by spin--orbit interaction under broken inversion symmetry. The\npicture is confirmed by a rigorous effective Hamiltonian theory, which reveals\nthat the DM coefficient is given by the magnitude of the intrinsic spin\ncurrent. The expression is directly applicable to first principles calculations\nand clarifies the relation between the interaction and the electronic band\nstructures. Quantitative agreement with experimental results is obtained for\nthe skyrmion compounds Mn$_{1-x}$Fe$_x$Ge and Fe$_{1-x}$Co$_x$Ge.",
        "positive": "Thermodynamics of ultrasmall metallic grains in the presence of pairing\n  and exchange correlations: Mesoscopic fluctuations: We study the mesoscopic fluctuations of thermodynamic observables in a\nnanosized metallic grain in which the single-particle dynamics are chaotic and\nthe dimensionless Thouless conductance is large. Such a grain is modeled by the\nuniversal Hamiltonian describing the competition between exchange and pairing\ncorrelations. The exchange term is taken into account exactly by a\nspin-projection method, and the pairing term is treated in the static-path\napproximation together with small-amplitude quantal fluctuations around each\nstatic fluctuation of the pairing field. Odd-even particle-number effects\ninduced by pairing correlations are included using a number-parity projection.\nWe find that the exchange interaction shifts the number-parity effects in the\nheat capacity and spin susceptibility to lower temperatures. In the regime\nwhere the pairing gap is similar to or smaller than the single-particle mean\nlevel spacing, these number-parity effects are suppressed by exchange\ncorrelations, and the fluctuations of the spin susceptibility may be\nparticularly large. However, for larger values of the pairing gap, the\nnumber-parity effects may be enhanced by exchange correlations."
    },
    {
        "anchor": "Giant Transport Anisotropy in ReS$_2$ Revealed via Nanoscale Conducting\n  Path Control: The low in-plane symmetry in layered 1T'-ReS$_2$ results in strong band\nanisotropy, while its manifestation in the electronic properties is challenging\nto resolve due to the lack of effective approaches for controlling the local\ncurrent path. In this work, we reveal the giant transport anisotropy in\nmonolayer to four-layer ReS$_2$ by creating directional conducting paths via\nnanoscale ferroelectric control. By reversing the polarization of a\nferroelectric polymer top layer, we induce conductivity switching ratio of\n>1.5x10$^8$ in the ReS$_2$ channel at 300 K. Characterizing the domain-defined\nconducting nanowires in an insulating background shows that the conductivity\nratio between the directions along and perpendicular to the Re-chain can exceed\n5.5x10$^4$. Theoretical modeling points to the band origin of the transport\nanomaly, and further reveals the emergence of a flat band in few-layer ReS$_2$.\nOur work paves the path for implementing the highly anisotropic 2D materials\nfor designing novel collective phenomena and electron lensing applications.",
        "positive": "Many-particle effects in the cyclotron resonance of encapsulated\n  monolayer graphene: We study the infrared cyclotron resonance of high mobility monolayer graphene\nencapsulated in hexagonal boron nitride, and simultaneously observe several\nnarrow resonance lines due to interband Landau level transitions. By holding\nthe magnetic field strength, $B$, constant while tuning the carrier density,\n$n$, we find the transition energies show a pronounced non-monotonic dependence\non the Landau level filling factor, $\\nu\\propto n/B$. This constitutes direct\nevidence that electron-electron interactions contribute to the Landau level\ntransition energies in graphene, beyond the single-particle picture.\nAdditionally, a splitting occurs in transitions to or from the lowest Landau\nlevel, which is interpreted as a Dirac mass arising from coupling of the\ngraphene and boron nitride lattices."
    },
    {
        "anchor": "Generalization of Zak's phase for lattice models with non-centered\n  inversion symmetry axis: We show how the presence of inversion symmetry in a one-dimensional (1D)\nlattice model is not a sufficient condition for a quantized Zak's phase. This\nis only the case when the inversion axis is at the center of the unit cell.\nWhen the inversion axis is not at the center, the modified inversion operator\nwithin the unit cell gains a k-dependence in some of its matrix elements which\nadds a correction term to the usual Zak's phase expression1, making it in\ngeneral deviate from its quantized value. A general expression that recovers a\nquantized Zak's phase in a lattice model with a unit cell of arbitrary size and\narbitrarily positioned inversion axis is provided in this paper, which relates\nthe quantized value with the eigenvalues of a modified parity operator at the\ninversion invariant momenta.",
        "positive": "Reducing error rates in straintronic multiferroic dipole-coupled\n  nanomagnetic logic by pulse shaping: Dipole-coupled nanomagnetic logic (NML), where nanomagnets with bistable\nmagnetization states act as binary switches and information is transferred\nbetween them via dipole coupling and Bennett clocking, is a potential\nreplacement for conventional transistor logic since magnets dissipate less\nenergy than transistors when they switch in response to the clock. However,\ndipole-coupled NML is much more error-prone than transistor logic because\nthermal noise can easily disrupt magnetization dynamics. Here, we study a\nparticularly energy-efficient version of dipole-coupled NML known as\nstraintronic multiferroic logic (SML) where magnets are clocked/switched with\nelectrically generated mechanical strain. By appropriately shaping the voltage\npulse that generates strain, the error rate in SML can be reduced to tolerable\nlimits. In this paper, we describe the error probabilities associated with\nvarious stress pulse shapes and discuss the trade-off between error rate and\nswitching speed in SML."
    },
    {
        "anchor": "Regioselective On-Surface Synthesis of [3]Triangulene Graphene\n  Nanoribbons: The integration of low-energy states into bottom-up engineered graphene\nnanoribbons (GNRs) is a robust strategy for realizing materials with tailored\nelectronic band structure for nanoelectronics. Low-energy zero-modes (ZMs) can\nbe introduced into nanographenes (NGs) by creating an imbalance between the two\nsublattices of graphene. This phenomenon is exemplified by the family of\n[n]triangulenes. Here, we demonstrate the synthesis of [3]triangulene-GNRs, a\nregioregular one-dimensional (1D) chain of [3]triangulenes linked by\nfive-membered rings. Hybridization between ZMs on adjacent [3]triangulenes\nleads to the emergence of a narrow band gap, Eg = 0.7 eV, and topological end\nstates that are experimentally verified using scanning tunneling spectroscopy\n(STS). Tight-binding and first-principles density functional theory (DFT)\ncalculations within the local spin density approximation (LSDA) corroborate our\nexperimental observations. Our synthetic design takes advantage of a selective\non-surface head-to-tail coupling of monomer building blocks enabling the\nregioselective synthesis of [3]triangulene-GNRs. Detailed ab initio theory\nprovides insight into the mechanism of on-surface radical polymerization,\nrevealing the pivotal role of Au-C bond formation/breakage in driving\nselectivity.",
        "positive": "Sub Decoherence Time Generation and Detection of Orbital Entanglement: Recent experiments have demonstrated sub decoherence time control of\nindividual single-electron orbital qubits. Here we propose a quantum dot based\nscheme for generation and detection of pairs of orbitally entangled electrons\non a timescale much shorter than the decoherence time. The electrons are\nentangled, via two-particle interference, and transferred to the detectors\nduring a single cotunneling event, making the scheme insensitive to charge\nnoise. For sufficiently long detector dot lifetimes, cross-correlation\ndetection of the dot charges can be performed with real-time counting\ntechniques, opening up for an unambiguous short-time Bell inequality test of\norbital entanglement."
    },
    {
        "anchor": "Feedback control of nuclear hyperfine fields in double quantum dot: In a coupled double quantum dot system, we present a theory for the interplay\nbetween electron and nuclear spins when the two-electron singlet state is\nbrought into resonance with one triplet state in moderate external magnetic\nfield. We show that the quantum interference between first order and second\norder hyperfine processes can lead to a feedback mechanism for manipulating the\nnuclear hyperfine fields. In a uniform external field, positive and negative\nfeedback controls can be realized for the gradient of the longitudinal\nhyperfine field as well as the average transverse hyperfine field in the double\ndot. The negative feedback which suppresses fluctuations in the longitudinal\nnuclear field gradient can enhance the decoherence time of singlet-triplet\nqubit to microsecond regime. We discuss the possibility of enhancing the\ndecoherence time of each individual spin in a cluster of dots using the\nnegative feedback control on the transverse nuclear field.",
        "positive": "Structure of quantum disordered wave functions: weak localization, far\n  tails, and mesoscopic transport: We report on the comprehensive numerical study of the fluctuation and\ncorrelation properties of wave functions in three-dimensional mesoscopic\ndiffusive conductors. Several large sets of nanoscale samples with finite\nmetallic conductance, modeled by an Anderson model with different strengths of\ndiagonal box disorder, have been generated in order to investigate both small\nand large deviations (as well as the connection between them) of the\ndistribution function of eigenstate amplitudes from the universal prediction of\nrandom matrix theory. We find that small, weak localization-type, deviations\ncontain both diffusive contributions (determined by the bulk and boundary\nconditions dependent terms) and ballistic ones which are generated by electron\ndynamics below the length scale set by the mean free path ell. By relating the\nextracted parameters of the functional form of nonperturbative deviations\n(``far tails'') to the exactly calculated transport properties of mesoscopic\nconductors, we compare our findings based on the full solution of the\nSchrodinger equation to different approximative analytical treatments. We find\nthat statistics in the far tail can be explained by the exp-log-cube\nasymptotics (convincingly refuting the log-normal alternative), but with\nparameters whose dependence on ell is linear and, therefore, expected to be\ndominated by ballistic effects. It is demonstrated that both small deviations\nand far tails depend explicitly on the sample size--the remaining puzzle then\nis the evolution of the far tail parameters with the size of the conductor\nsince short-scale physics is supposedly insensitive to the sample boundaries."
    },
    {
        "anchor": "Coupling graphene nanomechanical motion to a single-electron transistor: Graphene-based electromechanical resonators have attracted much interest\nrecently because of the outstanding mechanical and electrical properties of\ngraphene and their various applications. However, the coupling between\nmechanical motion and charge transport has not been explored in graphene. Here,\nwe studied the mechanical properties of a suspended 50-nm-wide graphene\nnanoribbon, which also acts as a single-electron transistor (SET) at low\ntemperature. Using the SET as a sensitive detector, we found that the resonance\nfrequency could be tuned from 82 MHz to 100 MHz and the quality factor exceeded\n30000. The strong charge-mechanical coupling was demonstrated by observing the\nSET induced ~140 kHz resonance frequency shifts and mechanical damping. We also\nfound that the SET can enhance the nonlinearity of the resonator. Our\nSET-coupled graphene mechanical resonator could approach an ultra-sensitive\nmass resolution of ~0.55*10^(-21) g and a force sensitivity of ~1.9*10^(-19)\nN/(Hz)^(1/2), and can be further improved. These properties indicate that our\ndevice is a good platform both for fundamental physical studies and potential\napplications.",
        "positive": "Finite-element dynamic-matrix approach for spin-wave dispersions in\n  magnonic waveguides with arbitrary cross section: We present a numerical approach to efficiently calculate spin-wave\ndispersions and spatial mode profiles in magnetic waveguides of arbitrarily\nshaped cross section with any non-collinear equilibrium magnetization which is\ntranslationally invariant along the waveguide. Our method is based on the\npropagating-wave dynamic-matrix approach by Henry et al. and extends it to\narbitrary cross sections using a finite-element method. We solve the linearized\nequation of motion of the magnetization only in a single waveguide cross\nsection which drastically reduces computational effort compared to common\nthree-dimensional micromagnetic simulations. In order to numerically obtain the\ndipolar potential of individual spin-wave modes, we present a plane-wave\nversion of the hybrid finite-element/boundary-element method by Frekdin and\nKoehler which, for the first time, we extend to a modified version of the\nPoisson equation. Our method is applied to several important examples of\nmagnonic waveguides including systems with surface curvature, such as magnetic\nnanotubes, where the curvature leads to an asymmetric spin-wave dispersion. In\nall cases, the validity of our approach is confirmed by other methods. Our\nmethod is of particular interest for the study of curvature-induced or\nmagnetochiral effects on spin-wave transport but also serves as an efficient\ntool to investigate standard magnonic problems."
    },
    {
        "anchor": "Current-induced spin torque resonance of magnetic insulators affected by\n  field-like spin-orbit torques and out-of-plane magnetizations: The spin-torque ferromagnetic resonance (ST-FMR) in a bilayer system\nconsisting of a magnetic insulator such as Y3Fe5O12 and a normal metal with\nspin-orbit interaction such as Pt is addressed theoretically. We model the\nST-FMR for all magnetization directions and in the presence of field-like\nspin-orbit torques based on the drift-diffusion spin model and quantum\nmechanical boundary conditions. ST-FMR experiments may expose crucial\ninformation about the spin-orbit coupling between currents and magnetization in\nthe bilayers.",
        "positive": "Validation of a quantized-current source with 0.2 ppm uncertainty: We report on high-accuracy measurements of quantized current, sourced by a\ntunable-barrier single-electron pump at frequencies $f$ up to $1$ GHz. The\nmeasurements were performed with a new picoammeter instrument, traceable to the\nJosephson and quantum Hall effects. Current quantization according to $I=ef$\nwith $e$ the elementary charge was confirmed at $f=545$ MHz with a total\nrelative uncertainty of 0.2 ppm, improving the state of the art by about a\nfactor of 5. For the first time, the accuracy of a possible future quantum\ncurrent standard based on single-electron transport was experimentally\nvalidated to be better than the best realization of the ampere within the\npresent SI."
    },
    {
        "anchor": "Spin-orbit effects on two-electron states in nanowhisker double quantum\n  dots: We investigate theoretically the combined effects of the electron-electron\nand the Rashba spin-orbit interactions on two electrons confined in\nquasi-one-dimensional AlInSb-based double quantum dots. We calculate the\ntwo-electron wave functions and explore the interplay between these two\ninteractions on the energy levels and the spin of the states. The energy\nspectrum as a function of an applied magnetic field shows crossings and\nanticrossings between triplet and singlet states, associated with level mixing\ninduced by the spin-orbit coupling. We find that the fields at which these\ncrossings occur can be naturally controlled by the interdot barrier width,\nwhich controls the exchange integral in the structure.",
        "positive": "Topological Excitonic Superfluids in Three Dimensions: We study the equilibrium and non-equilibrium properties of topological\ndipolar intersurface exciton condensates within time-reversal invariant\ntopological insulators in three spatial dimensions without a magnetic field. We\nelucidate that, in order to correctly identify the proper pairing symmetry\nwithin the condensate order parameter, the full three-dimensional Hamiltonian\nmust be considered. As a corollary, we demonstrate that only particles with\nsimilar chirality play a significant role in condensate formation. Furthermore,\nwe find that the intersurface exciton condensation is not suppressed by the\ninterconnection of surfaces in three-dimensional topological insulators as the\nintersurface polarizability vanishes in the condensed phase. This eliminates\nthe surface current flow leaving only intersurface current flow through the\nbulk. We conclude by illustrating how the excitonic superfluidity may be\nidentified through an examination of the terminal currents above and below the\ncondensate critical current."
    },
    {
        "anchor": "Detecting Perfect Transmission in Josephson Junctions on the Surface of\n  Three Dimensional Topological Insulators: We consider Josephson junctions on surfaces of three dimensional topological\ninsulator nanowires. We find that in the presence of a parallel magnetic field,\nshort junctions on nanowires show signatures of a perfectly transmitted mode\ncapable of supporting Majorana fermions. Such signatures appear in the\ncurrent-phase relation in the presence or absence of the fermion parity\nanomaly, and are most striking when considering the critical current as a\nfunction of flux \\Phi, which exhibits a peak at \\Phi=h/2e. The peak sharpens in\nthe presence of disorder at low but finite chemical potentials, and can be\neasily disentangled from weak-antilocalization effects. The peak also survives\nat small but finite temperatures, and represents a realistic and robust\nhallmark for perfect transmission and the emergence of Majorana physics inside\nthe wire.",
        "positive": "Spin-orbit coupled cold exciton condensates: We analyze theoretically the dynamics of degenerate condensate of cold\nindirect excitons. We account for both linear spin dependent terms arising from\nspin-orbit interaction of Rashba and Dresselhaus types and non-linear terms\ntransforming a pair of bright excitons into a pair of dark ones. We show that\nboth terms should lead to the qualitative changes in the dynamics of cold\nexciton droplets in the real space and time."
    },
    {
        "anchor": "Unidirectional propagation of zero-momentum magnons: We report on experimental observation of unidirectional propagation of\nzero-momentum magnons in synthetic antiferromagnet consisting of strained\nCoFeB/Ru/CoFeB trilayer. Inherent non-reciprocity of spin waves in synthetic\nantiferromagnets with uniaxial anisotropy results in smooth and monotonous\ndispersion relation around Gamma point, where the direction of the phase\nvelocity is reversed, while the group velocity direction is conserved. The\nexperimental observation of this phenomenon by intensity-, phase-, and\ntime-resolved Brillouin light scattering microscopy is corroborated by\nanalytical models and micromagnetic simulations.",
        "positive": "Anomalous Quantum Diffusion in Order-Disorder Separated Double Quantum\n  Ring: A novel feature for control of carrier mobility is explored in an\norder-disorder separated double quantum ring, where the two rings thread\ndifferent magnetic fluxes. Here we use simple tight-binding formulation to\ndescribe the system. In our model, the two rings are connected through a single\nbond and one of the rings is subjected to impurity, keeping the other ring as\nimpurity free. In the strong impurity regime, the electron diffusion length\nincreases with the increase of the impurity strength, while it decreases in the\nweak impurity regime. This phenomenon is completely opposite to that of a\nconventional disordered double quantum ring, where the electron diffusion\nlength always decreases with the increase of the disorder strength."
    },
    {
        "anchor": "Kondo effect and spin quenching in high-spin molecules on metal\n  substrates: Using a state-of-the art combination of density functional theory and\nimpurity solver techniques we present a complete and parameter-free picture of\nthe Kondo effect in the high-spin ($S=3/2$) coordination complex known as\nManganese Phthalocyanine adsorbed on the Pb(111) surface. We calculate the\ncorrelated electronic structure and corresponding tunnel spectrum and find an\nasymmetric Kondo resonance, as recently observed in experiments. Contrary to\nprevious claims, the Kondo resonance stems from only one of three possible\nKondo channels with origin in the Mn 3d-orbitals, its peculiar asymmetric shape\narising from the modulation of the hybridization due to strong coupling to the\norganic ligand. The spectral signature of the second Kondo channel is strongly\nsuppressed as the screening occurs via the formation of a many-body singlet\nwith the organic part of the molecule. Finally, a spin-1/2 in the 3d-shell\nremains completely unscreened due to the lack of hybridization of the\ncorresponding orbital with the substrate, hence leading to a spin-3/2\nunderscreened Kondo effect.",
        "positive": "Tunable electromagnetic environment for superconducting quantum bits: We introduce a setup which realises a tunable engineered environment for\nexperiments in circuit quantum electrodynamics. We illustrate this concept with\nthe specific example of a quantum bit, qubit, in a high-quality-factor cavity\nwhich is capacitively coupled to another cavity including a resistor. The\ntemperature of the resistor, which acts as the dissipative environment, can be\ncontrolled in a well defined manner in order to provide a hot or cold\nenvironment for the qubit, as desired. Furthermore, introducing superconducting\nquantum interference devices (SQUIDs) into the cavity containing the resistor,\nprovides control of the coupling strength between this artificial environment\nand the qubit. We demonstrate that our scheme allows us to couple strongly to\nthe environment enabling rapid initialization of the system, and by subsequent\ntuning of the magnetic flux of the SQUIDs we may greatly reduce the\nresistor-qubit coupling, allowing the qubit to evolve unhindered."
    },
    {
        "anchor": "Absence of quantum-confined Stark effect in GaN quantum disks embedded\n  in (Al,Ga)N nanowires grown by molecular beam epitaxy: Several of the key issues of planar (Al,Ga)N-based deep-ultraviolet light\nemitting diodes could potentially be overcome by utilizing nanowire\nheterostructures, exhibiting high structural perfection and improved light\nextraction. Here, we study the spontaneous emission of GaN/(Al,Ga)N nanowire\nensembles grown on Si(111) by plasma-assisted molecular beam epitaxy. The\nnanowires contain single GaN quantum disks embedded in long (Al,Ga)N nanowire\nsegments essential for efficient light extraction. These quantum disks are\nfound to exhibit intense emission at unexpectedly high energies, namely,\nsignificantly above the GaN bandgap, and almost independent of the disk\nthickness. An in-depth investigation of the actual structure and composition of\nthe nanowires reveals a spontaneously formed Al gradient both along and across\nthe nanowire, resulting in a complex core/shell structure with an Al deficient\ncore and an Al rich shell with continuously varying Al content along the entire\nlength of the (Al,Ga)N segment. This compositional change along the nanowire\ngrowth axis induces a polarization doping of the shell that results in a\ndegenerate electron gas in the disk, thus screening the built-in electric\nfields. The high carrier density not only results in the unexpectedly high\ntransition energies, but also in radiative lifetimes depending only weakly on\ntemperature, leading to a comparatively high internal quantum efficiency of the\nGaN quantum disks up to room temperature.",
        "positive": "Decoupling of Nucleation and Growth of ZnO nano-colloids in solution: In this paper, temporal growth and morphological evolution of ZnO\nnano-colloids were studied by in-situ UV-Vis absorption spectroscopy and\nTransmission Electron Microscopy (TEM) respectively. Nucleation of the\nnanoparticles was observed to occur within 10 sec in the solution after mixing\nthe precursors and there was not any significant change in morphology observed\nwith an increase in growth time. The morphological change was found to depend\non interfacial energy curvature. Decoupling of nucleation and growth parameters\nwas observed in the case of the atomically unbalanced reaction while aging of\nthe nanoparticles was found in atomically balanced reaction respectively. The\ngrowth of nano-particles was modeled using the Phase-field model (PFM) and\ncompared with the present in-situ growth process."
    },
    {
        "anchor": "Multiwalled nanotube faceting unravelled: Nanotubes show great promise for miniaturizing advanced technologies. Their\nexceptional physical properties are intimately related to their morphological\nand crystal structure. Circumferential faceting of multiwalled nanotubes\nreinforces their mechanical strength and alters their tribological and\nelectronic properties. Here, the nature of this important phenomenon is fully\nrationalized in terms of interlayer registry patterns. Regardless of the\nnanotube identity (that is, diameter, chirality, chemical composition),\nfaceting requires the matching of the chiral angles of adjacent layers. Above a\ncritical diameter that corresponds well with experimental results, achiral\nmultiwalled nanotubes display evenly spaced extended axial facets whose number\nequals the interlayer difference in circumferential unit cells. Elongated\nhelical facets, commonly observed in experiment, appear in nanotubes that\nexhibit small interlayer chiral angle mismatch. When the wall chiralities are\nuncorrelated, faceting is suppressed and outer layer corrugation, which is\ninduced by the moir\\'e superlattice, is obtained in agreement with experiments.\nFinally, we offer an explanation for the higher incidence of faceting in\nmultiwalled boron nitride nanotubes with respect to their carbon-based\ncounterparts.",
        "positive": "Berry Curvature Dipole and its Strain Engineering in Layered Phosphorene: The emergence of the fascinating non-linear Hall effect intrinsically depends\non the non-zero value of the Berry curvature dipole. In this work, we predict\nthat suitable strain engineering in layered van der Waals material phosphorene\ncan give rise to a significantly large Berry curvature dipole. Using symmetry\ndesign principles, and a combination of feasible strain and staggered on-site\npotentials, we show how a substantial Berry curvature dipole may be engineered\nat the Fermi level. We discover that monolayer phosphorene exhibits the most\nintense Berry curvature dipole peak near 11.8% strain, which is also a critical\npoint for the topological phase transition in pristine phosphorene.\nFurthermore, we have shown that the necessary strain value to achieve\nsubstantial Berry curvature dipole can be reduced by increasing the number of\nlayers. We have revealed that strain in these van der Waals systems not only\nalters the magnitude of Berry curvature dipole to a significant value but\nallows control over its sign. We are hopeful that our predictions will pave way\nto realize the non-linear Hall effect in such elemental van der Waals systems."
    },
    {
        "anchor": "Magnetoelectricity induced by rippling of magnetic nanomembranes and\n  wires: Magnetoelectric crystals have the interesting property that they allow\nelectric fields to induce magnetic polarizations, and vice versa, magnetic\nfields to generate ferroelectric polarizations. Having such a magnetoelectric\ncoupling usually requires complex types of magnetic textures, e.g., of\nspiralling type. Here we establish a novel approach to generate a linear\nmagnetoelectric coupling in insulators with a conventional, ferromagnetic\nground state. We show that nanoscale curved geometries lead to a reorganization\nof the magnetic texture that spontaneously breaks inversion symmetry and\nthereby induces macroscopic magnetoelectric multipoles. Specifically, we prove\nthat structural deformation in the form of controlled ripples activate a\nmagnetoelectric monopole in the recently synthesised two-dimensional magnets.\nWe also demonstrate that in zig-zag shaped ferromagnetic wires in planar\narchitectures, a magnetic toroidal moment triggers a direct linear\nmagnetoelectric coupling.",
        "positive": "Subgap states at ferromagnetic and spiral-ordered magnetic chains in\n  two-dimensional superconductors. II. Topological classification: We investigate the topological classification of the subgap bands induced in\na two-dimensional superconductor by a densely packed chain of magnetic moments\nwith ferromagnetic or spiral alignments. The wave functions for these bands are\ncomposites of Yu-Shiba-Rusinov-type states and magnetic scattering states and\nhave a significant spatial extension away from the magnetic moments. We show\nthat this spatial structure prohibits a straightforward extraction of a\nHamiltonian useful for the topological classification. To address the latter\ncorrectly we construct a family of spatially varying topological Hamiltonians\nfor the subgap bands adapted for the broken translational symmetry caused by\nthe chain. The spatial dependence in particular captures the transition to the\ntopologically trivial bulk phase when moving away from the chain by showing how\nthis, necessarily discontinuous, transition can be understood from an alignment\nof zeros with poles of Green's functions. Through the latter the topological\nHamiltonians reflect a characteristic found otherwise primarily in strongly\ninteracting systems."
    },
    {
        "anchor": "Geometrical Asymmetry Effect on Energy and Momentum Transfer Rates in a\n  Double-quantum-well Structure: Linear Regime: We investigate theoretically the effect of spatial asymmetry on the energy\nand momentum transfer rates in a double-quantum-well system using balance\nequation approach. Our study is limited to the linear regime where the applied\nelectric field is sufficiently weak. We calculate the screened potential by\nusing the random phase approximation and Hubbard approximation for the cases of\nhigh and low electron densities, respectively. Our numerical results predict\nthat the spatial asymmetry affects considerably both the energy transfer and\ndrag rates as a result of changes in plasmon modes. Also, we find that the\nspatial asymmetry effect disappears at lower temperatures by inclusion the\nshort-range interaction.",
        "positive": "Quantum localized modes in capacitively coupled Josephson junctions: We consider the quantum dynamics of excitations in a system of two\ncapacitively coupled Josephson junctions. Quantum breather states are found in\nthe middle of the energy spectrum of the confined nonescaping states of the\nsystem. They are characterized by a strong excitation of one junction. These\nstates perform slow tunneling motion from one junction to the other, while\nkeeping their coherent nature. The tunneling time sensitively depends on the\ninitial excitation energy. By using an external bias as a control parameter,\nthe tunneling time can be varied with respect to the escape time and the\nexperimentally limited coherence time. Thus one can control the flow of quantum\nexcitations between the two junctions."
    },
    {
        "anchor": "Observation of Floquet-Bloch states on the surface of a topological\n  insulator: The unique electronic properties of the surface electrons in a topological\ninsulator are protected by time-reversal symmetry. Circularly polarized light\nnaturally breaks time-reversal symmetry, which may lead to an exotic surface\nquantum Hall state. Using time- and angle-resolved photoemission spectroscopy,\nwe show that an intense ultrashort mid-infrared pulse with energy below the\nbulk band gap hybridizes with the surface Dirac fermions of a topological\ninsulator to form Floquet-Bloch bands. These photon dressed surface bands\nexhibit polarization-dependent band gaps at avoided crossings. Circularly\npolarized photons induce an additional gap at the Dirac point, which is a\nsignature of broken time-reversal symmetry on the surface. These observations\nestablish the Floquet-Bloch bands in solids and pave the way for optical\nmanipulation of topological quantum states of matter.",
        "positive": "Thermal conductivity of molybdenum disulfide nanotube from molecular\n  dynamics simulations: Single layer molybdenum disulfide (SLMoS2), a semiconductor possesses\nintrinsic bandgap and high electron mobility, has attracted great attention due\nto its unique electronic, optical, mechanical and thermal properties. Although\nthermal conductivity of SLMoS2 has been widely investigated recently, less\nstudies focus on molybdenum disulfide nanotube (MoS2NT). Here, the\ncomprehensive temperature, size and strain effect on thermal conductivity of\nMoS2NT are investigated. A chirality-dependent strain effect is identified in\nthermal conductivity of zigzag nanotube, in which the phonon group velocity can\nbe significantly reduced by strain. Besides, results show that thermal\nconductivity has a ~T-1 and a ~L\\b{eta} relation with temperature from 200 to\n400 K and length from 10 to 320 nm, respectively. This work not only provides\nfeasible strategies to modulate the thermal conductivity of MoS2NT, but also\noffers useful insights into the fundamental mechanisms that govern the thermal\nconductivity, which can be used for the thermal management of low dimensional\nmaterials in optical, electronic and thermoelectrical devices. Introduction."
    },
    {
        "anchor": "Conductance of telescoped double-walled nanotubes from perturbation\n  calculations: In a telescoped double-walled nanotube (TDWNT), with the inner tube partially\nextracted from the outer tube, the total current is forced to flow between the\nlayers. Considering the interlayer Hamiltonian as a perturbation, we can obtain\nan analytic formula for the interlayer conductance. The accuracy of the\nperturbation formula is systematically improved by including higher-order\nterms. The interlayer interaction effective in the perturbation formula is the\nproduct of the interlayer Hamiltonian and the wave function. It clarifies the\neffects of the spatial range of the interlayer Hamiltonian and the band energy\nshift.",
        "positive": "Sommerfeld enhancement factor in two-dimensional Dirac materials: In this work the above-band gap absorption spectrum in two-dimensional Dirac\nmaterials is calculated with account for the interaction between the\nphotocarriers. Both the screened Rytova-Keldysh and pure Coulomb attraction\npotentials between the electron and hole are used in the study. We find that,\nin the materials under consideration, the interaction enhances the absorbance\nin the narrow interband edge region, in a sharp contrast to the band model with\nthe parabolic free-carrier energy dispersion. We develop an approximation of\nthe weak interaction which allows us to reproduce the main features of the\nexactly calculated Sommerfeld factor. We show a substantial reduction of this\nfactor at higher frequencies due to the single-particle energy renormalization."
    },
    {
        "anchor": "Realization of a double-slit SQUID geometry by Fermi arc surface states\n  in a WTe$_2$ Weyl semimetal: We experimentally study electron transport between two superconducting indium\nleads, coupled to the WTe$_2$ crystal surface. WTe$_2$ is characterized by\npresence of Fermi arc surface states, as a predicted type-II Weyl semimetal\ncandidate. We demonstrate Josephson current in unprecedentedly long 5~$\\mu$m\nIn-WTe$_2$-In junctions, which is confirmed by $I-V$ curves evolution with\ntemperature and magnetic field. The Josephson current is mostly carried by the\ntopological surface states, which we demonstrate in a double-slit SQUID\ngeometry, realized by coupling the opposite WTe$_2$ crystal surfaces.",
        "positive": "Initiating and monitoring the evolution of single electrons within\n  atom-defined structures: Using a non-contact atomic force microscope we track and manipulate the\nposition of single electrons confined to atomic structures engineered from\nsilicon dangling bonds (DBs) on the hydrogen terminated silicon surface. By\nvarying the probe-sample separation we mechanically manipulate the equilibrium\nposition of individual surface silicon atoms and use this to directly switch\nthe charge state of individual DBs. Because this mechanism is based on short\nrange interactions and can be performed without applied bias voltage, we\nmaintain both site-specific selectivity and single-electron control. We extract\nthe short range forces involved with this mechanism by subtracting the long\nrange forces acquired on a dimer vacancy site. As a result of relaxation of the\nsilicon lattice to accommodate negatively charged DBs we observe charge\nconfigurations of DB structures that remain stable for many seconds at 4.5 K.\nSubsequently we use charge manipulation to directly prepare the ground state\nand metastable charge configurations of DB structures composed of up to six\natoms."
    },
    {
        "anchor": "Dynamics of quantum cellular automata electron transition in triple\n  quantum dots: The quantum cellular automata (QCA) effect is a transition in which multiple\nelectron move coordinately by Coulomb interactions and observed in multiple\nquantum dots. This effect will be useful for realizing and improving quantum\ncellular automata and information transfer using multiple electron transfer. In\nthis paper, we investigate the real-time dynamics of the QCA charge transitions\nin a triple quantum dot by using fast charge-state readout realized by rf\nreflectometry. We observe real-time charge transitions and analyze the\ntunneling rate comparing with the first-order tunneling processes. We also\nmeasure the gate voltage dependence of the QCA transition and show that it can\nbe controlled by the voltage.",
        "positive": "Alice string in Non-Hermitian Systems: Alice string is a topological defect with a very peculiar feature. When a\ndefect with a monopole charge encircles an Alice string, the monopole charge\nchanges sign. In this work, we generalize this notion to momentum space of\nperiodic media with loss and gain. In particular, we find that the generic\nband-structure node for a three-dimensional non-Hermitian crystalline system\nacts as an Alice string, which can flip the Chern number charge carried by Weyl\npoints and by exceptional-line rings. We discuss signatures of this topological\nstructure for a lattice model with one tuning parameter, including non-trivial\nbraiding of bulk band nodes, and the spectroscopic features of both the bulk\nand the surface states. We also explore how an Alice string affects the\nvalidity of the Nielsen-Ninomiya theorem, and present a mathematical\ndescription of the braiding phenomenon."
    },
    {
        "anchor": "Optical evidence of the chiral magnetic anomaly in Weyl semimetal TaAs: Chiral pumping from optical electric fields oscillating at THz frequencies is\nobserved in the Weyl material TaAs with electric and magnetic fields aligned\nalong both the a- and c-axes. Free carrier spectral weight enhancement is\nmeasured directly for the first time, confirming theoretical expectations of\nchiral pumping. A departure from linear field-dependence of the Drude weight is\nobserved at the highest fields in the quantum limit, providing direct evidence\nof field-dependent Fermi velocity of the chiral Landau level. Implications for\nthe chiral magnetic effect in Weyl semimetals from the optical f-sum rule are\ndiscussed.",
        "positive": "Uniform Electron Gas under An External Bias: The Generalized\n  Thomas-Fermi-Dirac Model and the Dual-Mean-Field Theory: The uniform electron gas placed between two reservoirs is used as a model\nsystem for molecular junctions under an external bias. The energetics of the\nelectron gas are calculated by generalizing the Thomas-Fermi-Dirac (TFD) model\nto nonequilibrium cases. We show that when the bias voltage is not zero, the\nfirst Hohenberg-Kohn (HK) theorem breaks down, and energies of the electron gas\ncan be determined by the total electron density together with the density of\nnonequilibrium electrons, supporting the dual-mean-field (DMF) theory recently\nproposed by us [J. Chem. Phys. 139, (2013) 191103]. The generalization of TFD\nfunctionals to DMF ones is also discussed."
    },
    {
        "anchor": "Fractional Chern Insulators vs. Non-Magnetic States in Twisted Bilayer\n  MoTe$_2$: Fractionally filled Chern bands with strong interactions may give rise to\nfractional Chern insulator (FCI) states, the zero-field analogue of the\nfractional quantum Hall effect. Recent experiments have demonstrated the\nexistence of FCIs in twisted bilayer MoTe$_2$ without external magnetic fields\n-- most robust at $\\nu=-2/3$ -- as well as Chern insulators (CIs) at $\\nu=-1$.\nAlthough the appearance of both of these states is theoretically natural in an\ninteracting topological system, experiments repeatedly observe nonmagnetic\nstates (lacking FCIs) at $\\nu=-1/3$ and $-4/3$, a puzzling result which has not\nbeen fully theoretically explained. In this work, we perform Hartree-Fock and\nexact diagonalization calculations to test whether the standard MoTe$_2$\nmoir\\'e model with the (greatly varying) parameter values available in the\nliterature can reproduce the non-magnetic states at $\\nu=-1/3$ and $-4/3$ in\nunison with the FCI at $\\nu=-2/3$ and CI state at $\\nu = -1$. We focus on the\nexperimentally relevant twist angles and, crucially, include remote bands. We\nfind that the parameters proposed in [Wang et al. (2023)] can nearly capture\nthe experimental phenomena at $\\nu=-1/3,-2/3,-1,-4/3$ simultaneously, though\nthe predicted ground states at $\\nu=-1/3$ are still mostly fully-spin-polarized\nand a larger dielectric constant $\\epsilon>10$ than is typical of hexagonal\nboron nitride (h-BN) substrate $\\epsilon\\sim 6$ is required. Our results show\nthe importance of remote bands in identifying the competing magnetic orders and\nlay the groundwork for further study of the realistic phase diagram.",
        "positive": "Four-dimensional Vibrational Spectroscopy for Nanoscale Mapping of\n  Phonon Dispersion in BN Nanotubes: Direct measurement of local phonon dispersion in individual nanostructures\ncan greatly advance our understanding of their electrical, thermal, and\nmechanical properties. However, such experimental measurements require\nextremely high detection sensitivity and combined spatial, energy and momentum\nresolutions, thus has been elusive. Here, we develop a four-dimensional\nelectron energy loss spectroscopy (4D-EELS) technique based a monochromated\nscanning transmission electron microscope (STEM), and present the\nposition-dependent phonon dispersion measurement in individual boron nitride\nnanotubes (BNNTs). Our measurement shows that the unfolded phonon dispersion of\nmulti-walled BNNTs is close to hexagonal-boron nitride (h-BN) crystals,\nsuggesting that interlayer coupling and curved geometry have no substantial\nimpacts on phonon dispersion. We also find that the acoustic phonons are\nextremely sensitive to momentum-dependent defect scattering, while optical\nphonons are much less susceptible. This work not only provides useful insights\ninto vibrational properties of BNNTs, but also demonstrates huge prospects of\nthe developed 4D-EELS technique in nanoscale phonon dispersion measurements."
    },
    {
        "anchor": "Minimal Geometry for Valley Filtering in Graphene: The possibility to effect valley splitting of an electronic current in\ngraphene represents the essential component in the new field of valleytronics\nin such two-dimensional materials. Based on a symmetry analysis of the\nscattering matrix, we show that if the spatial distribution of multiple\npotential scatterers breaks mirror symmetry about the axis of incoming\nelectrons, then a splitting of the current between two valleys is observed.\nThis leads to the appearance of the valley Hall effect. We illustrate the\neffect of mirror symmetry breaking in a minimal system of two symmetric\nimpurities, demonstrating the splitting between valleys via the differential\ncross sections and non-vanishing skew parameter. We further discuss the role\nthat these effects may play in transport experiments.",
        "positive": "Anomalous state of a 2DEG in vicinal Si MOSFET in high magnetic fields: We report the observation of an anomalous state of a 2D electron gas near a\nvicinal surface of a silicon MOSFET in high magnetic fields. It is\ncharacterised by unusual behaviour of the conductivities $\\sigma_{xx}$ and\n$\\sigma_{xy}$, which can be described as a collapse of the Zeeman spin\nsplitting accompanied by a large peak in $\\sigma_{xx}$ and an anomalous peak in\n$ \\sigma_{xy}$. It occurs at densities corresponding to the position of the\nFermi level above the onset of the superlattice mini-gap inherent to the\nvicinal system. The range of fields and densities where this effect exists has\nbeen determined, and it has been shown that it is suppressed by parallel\nmagnetic fields."
    },
    {
        "anchor": "Probing biexciton in monolayer WS$_2$ through controlled many-body\n  interaction: The monolayers of semiconducting transition metal dichalcogenides host\nstrongly bound excitonic complexes and are an excellent platform for exploring\nmany-body physics. Here we demonstrate a controlled kinetic manipulation of the\nfive-particle excitonic complex, the charged biexciton, through a systematic\ndependence of the biexciton peak on excitation power, gate voltage, and\ntemperature using steady-state and time-resolved photoluminescence (PL). With\nthe help of a combination of the experimental data and a rate equation model,\nwe argue that the binding energy of the charged biexciton is less than the\nspectral separation of its peak from the neutral exciton. We also note that\nwhile the momentum-direct radiative recombination of the neutral exciton is\nrestricted within the light cone, such restriction is relaxed for a charged\nbiexciton recombination due to the presence of near-parallel excited and final\nstates in the momentum space.",
        "positive": "One-dimensional electron localization in semiconductors coupled to\n  electromagnetic cavities: Electrical conductivity of one-dimensional (1d) disordered solids decays\nexponentially with their length, which is a celebrated manifestation of the\nlocalization phenomenon. Here, we study the modifications of localized\nconductivity induced by placement of 1d semiconductors inside of single-mode\nelectromagnetic cavities, focusing on the regime of non-degenerate doping. We\nuse the Green's function technique modified for the non-perturbative account of\ncavity excited states, and including both coherent electron-cavity effects\n(i.e. electron motion in the zero-point fluctuating field) and incoherent\nprocesses of photon emission upon tunneling. The energy spectrum of electron\ntransmission in the cavity acquires Fano-type resonances associated with\nvirtual photon emission, passage along the resonant level, and photon\nre-absorption. The quality factor of the Fano resonance depends on whether the\nintermediate state is coupled to the leads, and reaches its maximum when this\nstate is localized deep in the disorder potential. Coupling to the cavity also\nelevates the energies of the shallow bound states, bringing them to the\nconduction band bottom. Such an effect leads to the enhancement of the\nlow-temperature conductance."
    },
    {
        "anchor": "Photonics meets excitonics: natural and artificial molecular aggregates: Organic molecules store the energy of absorbed light in the form of\ncharge-neutral molecular excitations -- Frenkel excitons. Usually, in amorphous\norganic materials, excitons are viewed as quasiparticles, localized on single\nmolecules, which diffuse randomly through the structure. However, the picture\nof incoherent hopping is not applicable to some classes of molecular aggregates\n-- assemblies of molecules that have strong near field interaction between\nelectronic excitations in the individual subunits. Molecular aggregates can be\nfound in nature, in photosynthetic complexes of plants and bacteria, and they\ncan also be produced artificially in various forms including quasi-one\ndimensional chains, two-dimensional films, tubes, etc. In these structures\nlight is absorbed collectively by many molecules and the following dynamics of\nmolecular excitation possesses coherent properties. This energy transfer\nmechanism, mediated by the coherent exciton dynamics, resembles the propagation\nof electromagnetic waves through a structured medium on the nanometer scale.\nThe absorbed energy can be transferred resonantly over distances of hundreds of\nnanometers before exciton relaxation occurs. Furthermore, the spatial and\nenergetic landscape of molecular aggregates can enable the funneling of the\nexciton energy to a small number of molecules either within or outside the\naggregate. In this review we establish a bridge between the fields of photonics\nand excitonics by describing the present understanding of exciton dynamics in\nmolecular aggregates.",
        "positive": "Spinning superfluid helium-4 nanodroplets: We have studied spinning superfluid $^4$He nanodroplets at zero temperature\nusing Density Functional theory. Due to the irrotational character of the\nsuperfluid flow, the shapes of the spinning nanodroplets are very different\nfrom those of a viscous normal fluid drop in steady rotation. We show that when\nvortices are nucleated inside the superfluid droplets, their morphology, which\nevolves from axisymmetric oblate to triaxial prolate to two-lobed shapes, is in\ngood agreement with experiments. The presence of vortex arrays confers to the\nsuperfluid droplets the rigid-body behavior of a normal fluid in steady\nrotation, and this is the ultimate reason of the surprising good agreement\nbetween recent experiments and the classical models used for their description."
    },
    {
        "anchor": "Topological quantum properties of chiral crystals: Chiral crystals are materials whose lattice structure has a well-defined\nhandedness due to the lack of inversion, mirror, or other roto-inversion\nsymmetries. These crystals represent a broad, important class of quantum\nmaterials; their structural chirality has been found to allow for a wide range\nof phenomena in condensed matter physics, including skyrmions in chiral\nmagnets, unconventional pairing in chiral superconductors, nonlocal transport\nand unique magnetoelectric effects in chiral metals, as well as\nenantioselective photoresponse. Nevertheless, while these phenomena have been\nintensely investigated, the topological electronic properties of chiral\ncrystals have still remained largely uncharacterized. While recent theoretical\nadvances have shown that the presence of crystalline symmetries can protect\nnovel band crossings in 2D and 3D systems, we present a new class of Weyl\nfermions enforced by the absence of particular crystal symmetries. These\n\"Kramers-Weyl\" fermions are a universal topological electronic property of all\nnonmagnetic chiral crystals with spin-orbit coupling (SOC); they are guaranteed\nby lattice translation, structural chirality, and time-reversal symmetry, and\nunlike conventional Weyl fermions, appear at time-reversal-invariant momenta\n(TRIMs). We cement this finding by identifying representative chiral materials\nin the majority of the 65 chiral space groups in which Kramers-Weyl fermions\nare relevant to low-energy physics. By combining our analysis with the results\nof previous works, we determine that all point-like nodal degeneracies in\nnonmagnetic chiral crystals with relevant SOC carry nontrivial Chern numbers.\nWe further show that, beyond the previous phenomena allowed by structural\nchirality, Kramers-Weyl fermions enable unusual phenomena, such as a novel\nelectron spin texture, chiral bulk Fermi surfaces over large energy windows.",
        "positive": "Optical orientation of spins in GaAs:Mn/AlGaAs quantum wells via\n  impurity-to-band excitation: The paper reports optical orientation experiments performed in the narrow\nGaAs/AlGaAs quantum wells doped with Mn. We experimentally demonstrate a\ncontrol over the spin polarization by means of the optical orientation via the\nimpurity-to-band excitation and observe a sign inversion of the luminescence\npolarization depending on the pump power. The g factor of a hole localized on\nthe Mn acceptor in the quantum well was also found to be considerably modified\nfrom its bulk value due to the quantum confinement effect. This finding shows\nthe importance of the local environment on magnetic properties of the dopants\nin semiconductor nanostructures."
    },
    {
        "anchor": "Undamped energy transport by collective surface plasmon oscillations\n  along metallic nanosphere chain: The random-phase-approximation semiclassical scheme for description of\nplasmon excitations in large metallic nanospheres (with radius 10--100 nm) is\ndeveloped for a case of presence of dynamical electric field. The spectrum of\nplasmons in metallic nanosphere is determined including both surface and volume\ntype excitations and their mutual connections. It is demonstrated that only\nsurface plasmons of dipole type can be excited by a homogeneous dynamical\nelectric field. The Lorentz friction due to irradiation of e-m energy by\nplasmon oscillations is analysed with respect to the sphere dimension. The\nresulting shift of resonance frequency due to plasmon damping is compared with\nexperimental data for various sphere radii. Collective of wave-type\noscillations of surface plasmons in long chains of metallic spheres are\ndescribed. The undamped region of propagation of plasmon waves along the chain\nis found in agreement with some previous numerical simulations.",
        "positive": "Mode locking of hole spin coherences in CsPb(Cl,Br)$_3$ perovskite\n  nanocrystals: The spin physics of perovskite nanocrystals with confined electrons or holes\nis attracting increasing attention, both for fundamental studies and spintronic\napplications. Here, stable CsPb(Cl$_{0.5}$Br$_{0.5}$)$_3$ lead halide\nperovskite nanocrystals embedded in a fluorophosphate glass matrix are studied\nby time-resolved optical spectroscopy to unravel the coherent spin dynamics of\nholes and their interaction with nuclear spins of the $^{207}$Pb isotope. We\ndemonstrate the spin mode locking effect provided by the synchronization of the\nLarmor precession of single hole spins in each nanocrystal in the ensemble that\nare excited periodically by a laser in an external magnetic field. The mode\nlocking is enhanced by nuclei-induced frequency focusing. An ensemble spin\ndephasing time $T_2^*$ of a nanosecond and a single hole spin coherence time of\n$T_2=13\\,$ns are measured. The developed theoretical model accounting for the\nmode locking and nuclear focusing for randomly oriented nanocrystals with\nperovskite band structure describes the experimental data very well."
    },
    {
        "anchor": "Electron transport through single conjugated organic molecules: Basis\n  set effects in ab initio calculations: We investigate electron transport through single conjugated molecules -\nincluding benzenedithiol, oligo-phenylene-ethynylenes of different lengths, and\na ferrocene-containing molecule sandwiched between two gold electrodes with\ndifferent contact structures - by using a single-particle Green function method\ncombined with density functional theory calculation. We focus on the effect of\nthe basis set in the ab initio calculation. It is shown that the position of\nthe Fermi energy in the transport gap is sensitive to the molecule-lead charge\ntransfer which is affected by the size of basis set. This can dramatically\nchange, by orders of magnitude, the conductance for long molecules, though the\neffect is only minor for short ones. A resonance around the Fermi energy tends\nto pin the position of the Fermi energy and suppress this effect. The result is\ndiscussed in comparison with experimental data.",
        "positive": "Impact of the Fizeau drag effect on Goos-H\u00e4nchen shifts in graphene: We investigate the Goos-H\\\"{a}nchen shifts in reflection for a light beam\nwithin a graphene structure, utilizing the Fizeau drag effect induced by its\nmassless Dirac electrons in incident light. The magnitudes of spatial and\nangular shifts for a light beam propagating against the direction of drifting\nelectrons are significantly enhanced, while shifts for a beam co-propagating\nwith the drifting electrons are suppressed. The Goos-H\\\"{a}nchen shifts exhibit\naugmentation with increasing drift velocities of electrons in graphene. The\nimpact of incident wavelength on the angular and spatial shifts in reflection\nis discussed. Furthermore, the study highlights the crucial roles of the\ndensity of charged particles in graphene, the particle relaxation time, and the\nthickness of the graphene in manipulating the drag-affected Goos-H\\\"{a}nchen\nshifts. This investigation offers valuable insights for efficiently guiding\nlight in graphene structures under the influence of the Fizeau drag effect."
    },
    {
        "anchor": "A model for the study of the Shubnikov-de Haas and the integer quantum\n  Hall effects in a two dimensional electronic system: Up to know all the experimental results concerning the integer and fractional\nquantum Hall effect are related to semiconductor heterostructures (and more\nrecently with graphene). The common characteristic of all these systems is the\npresence of a reservoir of electrons, which, in fact, in the initial stage is\nthe source of the electrons, providing the two-dimensional electron gas (2DES).\nThen, any physical realization of a 2DES is necessarily embedded in a 3D\nstructure, which establishes the Fermi level. Hence, the 2DES appears to be an\nopen system. In this paper we present an analytical approach to the integer\nquantum Hall effect (IQHE) and the Shubnikov-de Haas (SdH) phenomena in the\n2DES, basing us in fundamental principles and showing the secondary role of the\nlocalized electron states in both phenomena. In fact, we show that the IQHE is\na consequence of the fluctuations of electrons in the 2DES. Once we obtain the\ndensity of states of the 2DES under the application of a magnetic field we\ncalculate both magnetoconductivities (diagonal and Hall) deducing them from the\nBoltzman semiclassical equation. The model proposed reproduces both phenomena,\nthe width of the Hall plateaus (with the precision reached in the experimental\nmeasurements, of the order of 10-8-10-9) and the corresponding minima of the\ndiagonal magnetoresistivity, and also the dependence with temperature of the\nIQHE and SdH.",
        "positive": "Exchange interactions and intermolecular hybridization in a spin-1/2\n  nanographene dimer: Phenalenyl is a radical nanographene with triangular shape that hosts an\nunpaired electron with spin S = 1/2. The open-shell nature of phenalenyl is\nexpected to be retained in covalently bonded networks. Here, we study a first\nstep in that direction and report the synthesis of the phenalenyl dimer by\ncombining in-solution synthesis and on-surface activation and its\ncharacterization both on Au(111) and on a monolayer of NaCl on top of Au(111)\nby means of inelastic electron tunneling spectroscopy (IETS). IETS shows\ninelastic steps that, together with a thorough theoretical analysis, are\nidentified as the singlet-triplet excitation arising from interphenalenyl\nexchange. Two prominent features of our data permit to shed light on the nature\nof spin interactions in this system. First, the excitation energies with and\nwithout the NaCl decoupling layer are 48 and 41 meV, respectively, indicating a\nsignificant renormalization of the spin excitation energies due to exchange\nwith the Au(111) electrons. Second, a position-dependent bias-asymmetry of the\nheight of the inelastic steps is accounted for by an interphenalenyl\nhybridization of the singly occupied phenalenyl orbitals that is only possible\nvia third neighbor hopping. This hybridization is also essential to activate\nkinetic interphenalenyl exchange. Our results set the stage for future work on\nthe bottom-up synthesis of spin S = 1/2 spin lattices with large exchange\ninteraction."
    },
    {
        "anchor": "Floquet Weyl Phases in a Three Dimensional Network Model: We study the topological properties of 3D Floquet bandstructures, which are\ndefined using unitary evolution matrices rather than Hamiltonians. Previously,\n2D bandstructures of this sort have been shown to exhibit anomalous topological\nbehaviors, such as topologically-nontrivial zero-Chern-number phases. We show\nthat the bandstructure of a 3D network model can exhibit Weyl phases, which\nfeature \"Fermi arc\" surface states like those found in Weyl semimetals. Tuning\nthe network's coupling parameters can induce transitions between Weyl phases\nand various topologically distinct gapped phases. We identify a connection\nbetween the topology of the gapped phases and the topology of Weyl point\ntrajectories in k-space. The model is feasible to realize in custom\nelectromagnetic networks, where the Weyl point trajectories can be probed by\nscattering parameter measurements.",
        "positive": "Measurable lattice effects on the charge and magnetic response in\n  graphene: The simplest tight-binding model is used to study lattice effects on two\nproperties of doped graphene: i) magnetic orbital susceptibility and ii)\nregular Friedel oscillations, both suppressed in the usual Dirac cone\napproximation. i) An exact expression for the tight-binding magnetic\nsusceptibility is obtained, leading to orbital paramagnetism in graphene for a\nwide range of doping levels which is relevant when compared with other\ncontributions. ii) Friedel oscillations in the coarse-grained charge response\nare considered numerically and analytically and an explicit expression for the\nresponse to lowest order in lattice effects is presented, showing the\nrestoration of regular 2d behavior, but with strong sixfold anisotropy."
    },
    {
        "anchor": "Two-Stage Kondo Effect and Kondo Box Level Spectroscopy in a Carbon\n  Nanotube: The concept of the \"Kondo box\" describes a single spin, antiferromagnetically\ncoupled to a quantum dot with a finite level spacing. Here, a Kondo box is\nformed in a carbon nanotube interacting with a localized electron. We\ninvestigate the spins of its first few eigenstates and compare them to a recent\ntheory. In an 'open' Kondo-box, strongly coupled to the leads, we observe a\nnon-monotonic temperature dependence of the nanotube conductance, which results\nfrom a competition between the Kondo-box singlet and the 'conventional' Kondo\nstate that couples the nanotube to the leads.",
        "positive": "Mechanical modulation of single-electron tunneling through\n  molecular-assembled metallic nanoparticles: We present a microscopic study of single-electron tunneling in nanomechanical\ndouble-barrier tunneling junctions formed using a vibrating scanning nanoprobe\nand a metallic nanoparticle connected to a metallic substrate through a\nmolecular bridge. We analyze the motion of single electrons on and off the\nnanoparticle through the tunneling current, the displacement current and the\ncharging-induced electrostatic force on the vibrating nanoprobe. We demonstrate\nthe mechanical single-electron turnstile effect by applying the theory to a\ngold nanoparticle connected to the gold substrate through alkane dithiol\nmolecular bridge and probed by a vibrating platinum tip."
    },
    {
        "anchor": "A one-dimensional spin-orbit interferometer: We demonstrate that the combination of an external magnetic field and the\nintrinsic spin-orbit interaction results in nonadiabatic precession of the\nelectron spin after transmission through a quantum point contact (QPC). We\nsuggest that this precession may be observed in a device consisting of two QPCs\nplaced in series. The pattern of resonant peaks in the transmission is strongly\ninfluenced by the non-abelian phase resulting from this precession. Moreover, a\nnovel type of resonance which is associated with suppressed, rather than\nenhanced, transmission emerges in the strongly nonadiabatic regime. The shift\nin the resonant transmission peaks is dependent on the spin-orbit interaction\nand therefore offers a novel way to directly measure these interactions in a\nballistic 1D system.",
        "positive": "The Microwave Hall Effect: This paper describes a simple microwave apparatus to measure the Hall effect\nin semiconductor wafers. The advantage of this technique is that it does not\nrequire contacts on the sample or the use of a resonant cavity. Our method\nconsists of placing the semiconductor wafer into a slot cut in an X-band (8 -\n12 GHz) waveguide series tee, injecting microwave power into the two opposite\narms of the tee, and measuring the microwave output at the third arm. A\nmagnetic field applied perpendicular to the wafer gives a microwave Hall signal\nthat is linear in the magnetic field and which reverses phase when the magnetic\nfield is reversed. The microwave Hall signal is proportional to the\nsemiconductor mobility, which we compare for calibration purposes with d. c.\nmobility measurements obtained using the van der Pauw method. We obtain the\nresistivity by measuring the microwave reflection coefficient of the sample.\nThis paper presents data for silicon and germanium samples doped with boron or\nphosphorus. The measured mobilities ranged from 270 to 3000 cm2 /(V-sec)."
    },
    {
        "anchor": "Energy absorption in time-dependent unitary random matrix ensembles:\n  dynamic vs Anderson localization: We consider energy absorption in an externally driven complex system of\nnoninteracting fermions with the chaotic underlying dynamics described by the\nunitary random matrices. In the absence of quantum interference the energy\nabsorption rate W(t) can be calculated with the help of the linear-response\nKubo formula. We calculate the leading two-loop interference correction to the\nsemiclassical absorption rate for an arbitrary time dependence of the external\nperturbation. Based on the results for periodic perturbations, we make a\nconjecture that the dynamics of the periodically-driven random matrices can be\nmapped onto the one-dimensional Anderson model. We predict that in the regime\nof strong dynamic localization W(t) ln(t)/t^2 rather than decays exponentially.",
        "positive": "Stacking-dependent spin interactions in Pd/Fe bilayers on Re(0001): Using spin-polarized scanning tunneling microscopy and density functional\ntheory, we have studied the magnetic properties of Pd/Fe atomic bilayers on\nRe(0001). Two kinds of magnetic ground states are discovered due to different\ntypes of stacking of the Pd adlayer on Fe/Re(0001). For fcc-stacking of Pd on\nFe/Re(0001), it is a spin spiral propagating along the close-packed direction\nwith a period of about 0.9 nm, driven by frustrated exchange and\nDzyaloshinskii-Moriya interactions. For the hcp stacking, the higher-order\nexchange interactions stabilize an uudd (up-up-down-down) state propagating\nperpendicular to the close-packed direction with a period of about 1.0 nm."
    },
    {
        "anchor": "Nonlinear intensity dependence of photogalvanics and photoconductance\n  induced by terahertz laser radiation in twisted bilayer graphene close to\n  magic angle: We report on the observation of the nonlinear intensity dependence of the\nbulk photogalvanic current and photoconductivity in the twisted graphene with\nsmall twist angles close to the second magical angle. We show that terahertz\nradiation results in the photoresponses, which is caused by indirect optical\ntransitions (free carrier absorption), direct interband transitions and optical\ntransitions between Moir\\'e subbands. The relative contribution of these\nabsorption channels depends on the Fermi level position with respect to the\nmultiple Moir\\'e subbands of the twisted graphene. The interplay of these\nabsorption channels results in oscillations of the photoresponses with\nvariation of the gate voltage. We show that the photoresponse saturates at high\nintensities. For different absorption channels it has different intensity\ndependencies and saturation intensities. The latter depends non-monotonically\non the Fermi level position, which is controlled by the gate voltage.",
        "positive": "Lateral NbS$_2$/MoS$_2$/NbS$_2$ transistors: physical modeling and\n  performance assessment: Reducing the contact resistance of field-effect transistors based on\ntwo-dimensional materials is one of the key improvements required to to enable\nthe integration of such transistors in an industrially relevant process.\nSuitably designed lateral heterojunctions provide an opportunity to\nindependently tailor the contact and channel properties and to mitigate the\nproblem of high contact resistance. Inspired by the recent experimental\ndemonstration of a two-dimensional $p$-type Schottky barrier, here we use\nquantum transport simulations to estimate the performance of $p$-type\ntransistors in which the channel consists of a lateral heterostructure of\nNbS$_2$/MoS$_2$/NbS$_2$ (semimetal-semiconductor-semimetal). We find that the\ngate alignment with the channel is a critical design parameter, strongly\ninfluencing the capability of the gate to modulate the Schottky barrier at the\nMoS$_2$/NbS$_2$ interfaces. This effect is also found to significantly affect\nthe scaling behavior of the device."
    },
    {
        "anchor": "Noise insights into electronic transport: Typical experimental measurement is set up as a study of the system's\nresponse to a stationary external excitation. This approach considers any\nrandom fluctuation of the signal as spurious contribution which is to be\neliminated via time-averaging or, equivalently, bandwidth reduction. Beyond\nthat lies a conceptually different paradigm -- the measurement of the system's\nspontaneous fluctuations. The goal of this overview article is to demonstrate\nhow current noise measurements bring insight into hidden features of electronic\ntransport in various mesoscopic conductors, ranging from 2D topological\ninsulators to individual carbon nanotubes.",
        "positive": "Atomistic theory of electronic and optical properties of InAsP/InP\n  nanowire quantum dots: We present here an atomistic theory of the electronic and optical properties\nof hexagonal InAsP quantum dots in InP nanowires in the wurtzite phase. These\nself-assembled quantum dots are unique in that their heights, shapes, and\ndiameters are well known. Using a combined valence-force-field, tight-binding,\nand configuration-interaction approach we perform atomistic calculations of\nsingle-particle states and excitonic, biexcitonic and trion complexes as well\nas emission spectra as a function of the quantum dot height, diameter and As\nversus P concentration. The atomistic tight-binding parameters for InAs and InP\nin the wurtzite crystal phase were obtained by ab initio methods corrected by\nempirical band gaps. The low energy electron and hole states form electronic\nshells similar to parabolic or cylindrical quantum confinement, only weakly\naffected by hexagonal symmetry and As fluctuations. The relative alignment of\nthe emission lines from excitons, trions and biexcitons agrees with that for\nInAs/InP dots in the zincblende phase in that biexcitons and positive trions\nare only weakly bound. The random distribution of As atoms leads to dot-to-dot\nfluctuations of a few meV for the single-particle states and the spectral\nlines. Due to the high symmetry of hexagonal InAsP nanowire quantum dots the\nexciton fine structure splitting is found to be small, of the order a few\n$\\mu$eV with significant random fluctuations in accordance with experiments."
    },
    {
        "anchor": "Controllable valley and spin transports in ferromagnetic silicene\n  junctions: We investigate charge, valley, and spin transports in\nnormal/ferromagnetic/normal silicene junc- tion. We show that the charge,\nvalley, and spin conductances in this junction oscillate with the length of the\nferromagnetic silicene. It is also found that the current through this junction\nis valley and spin polarized due to the coupling between valley and spin\ndegrees of freedom, and the valley and spin polarizations can be tuned by local\napplication of a gate voltage. In particular, we find fully valley and spin\npolarized current by applying the electric field. We also obtain the condition\nfor observing the fully valley and spin polarized current.",
        "positive": "Quantum transport through single-molecule junctions with orbital\n  degeneracies: We consider electronic transport through a single-molecule junction where the\nmolecule has a degenerate spectrum. Unlike previous transport models, and\ntheories a rate-equations description is no longer possible, and the quantum\ncoherences between degenerate states have to be taken into account. We present\nthe derivation and application of a master equation that describes the system\nin the weak-coupling limit and give an in-depth discussion of the parameter\nregimes and the new phenomena due to coherent on-site dynamics."
    },
    {
        "anchor": "PT-symmetric Non-Hermitian Hopf Metal: Hopf insulator is a representative class of three-dimensional topological\ninsulators beyond the standard topological classification methods based on\nK-theory. In this letter, we discover the metallic counterpart of the Hopf\ninsulator in the non-Hermitian systems. While the Hopf invariant is not a\nstable topological index due to the additional non-Hermitian degree of freedom,\nwe show that the PT-symmetry stabilizes the Hopf invariant even in the presence\nof the non-Hermiticity. In sharp contrast to the Hopf insulator phase in the\nHermitian counterpart, we discover an interesting result that the non-Hermitian\nHopf bundle exhibits the topologically protected non-Hermitian degeneracy,\ncharacterized by the two-dimensional surface of exceptional points. Despite the\nnon-Hermiticity, the Hopf metal has the quantized Zak phase, which results in\nbulk-boundary correspondence by showing drumhead-like surface states at the\nboundary. Finally, we show that, by breaking PT-symmetry, the nodal surface\ndeforms into the knotted exceptional lines. Our discovery of the Hopf metal\nphase firstly confirms the existence of the non-Hermitian topological phase\noutside the framework of the standard topological classifications.",
        "positive": "Terahertz Laser Combs in Graphene Field-Effect Transistors: Electrically injected terahertz (THz) radiation sources are extremely\nappealing given their versatility and miniaturization potential, opening the\nvenue for integrated-circuit THz technology. In this work, we show that\ncoherent THz frequency combs in the range\n$0.5~\\mathrm{THz}<\\omega/2\\pi<10~\\mathrm{THz}$ can be generated making use of\ngraphene plasmonics. Our setup consists of a graphene field-effect transistor\nwith asymmetric boundary conditions, with the radiation originating from a\nplasmonic instability that can be controlled by direct current injection. We\nput forward a combined analytical and numerical analysis of the graphene plasma\nhydrodynamics, showing that the instability can be experimentally controlled by\nthe applied gate voltage and the injected current. Our calculations indicate\nthat the emitted THz comb exhibits appreciable temporal coherence\n($g^{(1)}(\\tau)>0.6$) and radiant emittance ($10^{7}\\,\\mathrm{Wm^{-2}}$). This\nmakes our scheme an appealing candidate for a graphene-base THz laser source.\nMoreover, a mechanism for the instability amplification is advanced for the\ncase of substrates with varying electric permitivitty, which allows to overcome\neventual limitations associated with the experimental implementation."
    },
    {
        "anchor": "Electric dipole spin resonance at shallow donors in quantum wires: Electric dipole spin resonance is studied theoretically at a shallow donor\nformed in a nanowire with spin-orbit coupling in a magnetic field. Such system\nmay represent a donor-based qubit. The single discrete energy level of the\ndonor is accompanied by the set of continuum states, which provide a\nnon-trivial interplay for the picture of electric dipole spin resonance driven\nby an external monochromatic field. Strongly nonlinear dependencies of spin\nflip time as well as of the coordinate mean values on the electric field\namplitude are observed, demonstrating the significance of coupling to the\ncontinuum for spin-based qubits manipulation in nanostructures.",
        "positive": "Probing Spin-Polarized Currents in the Quantum Hall Regime: An experiment to probe spin-polarized currents in the quantum Hall regime is\nsuggested that takes advantage of the large Zeeman-splitting in the\nparamagnetic diluted magnetic semiconductor zinc manganese selenide\n(Zn$_{1-x}$Mn$_x$Se). In the proposed experiment spin-polarized electrons are\ninjected by ZnMnSe-contacts into a gallium arsenide (GaAs) two-dimensional\nelectron gas (2DEG) arranged in a Hall bar geometry. We calculated the\nresulting Hall resistance for this experimental setup within the framework of\nthe Landauer-B\\\"uttiker formalism. These calculations predict for 100%\nspininjection through the ZnMnSe-contacts a Hall resistance twice as high as in\nthe case of no spin-polarized injection of charge carriers into a 2DEG for\nfilling factor $\\nu=2$. We also investigated the influence of the equilibration\nof the spin-polarized electrons within the 2DEG on the Hall resistance. In\naddition, in our model we expect no coupling between the contact and the 2DEG\nfor odd filling factors of the 2DEG for 100% spininjection, because of the\nopposite sign of the g-factors of ZnMnSe and GaAs."
    },
    {
        "anchor": "Spin wave beam propagation in ferromagnetic thin film with graded\n  refractive index: mirage effect and prospective applications: Using analysis of iso-frequency contours of the spin-wave dispersion\nrelation, supported by micromagnetic simulations, we study the propagation of\nspin-wave (SW) beams in thin ferromagnetic films through the areas of the\ninhomogeneous refractive index. We compare the transmission and reflection of\nSWs in areas with gradual and step variation of the SW refractive index. In\nparticular, we show the mirage effect for SWs with narrowing SW beam width, and\nan application of the gradual modulation of the SWs refractive index as a\ndiverging lens. Furthermore, we study the propagation of SWs in ferromagnetic\nstripe with modulated refractive index. We demonstrate that the system can be\nconsidered as the graded-index waveguide, which preserves the width of the SW\nbeam for a long distance-the property essential for prospective applications of\nmagnonics.",
        "positive": "Hot Carriers from Intra- and Interband Transitions in Gold-Silver Alloy\n  Nanoparticles: Hot electrons and holes generated from the decay of localized surface\nplasmons in metallic nanoparticles can be harnessed for applications in solar\nenergy conversion and sensing. In this paper, we study the generation of hot\ncarriers in large spherical gold-silver alloy nanoparticles using a recently\ndeveloped atomistic modelling approach that combines a solution of Maxwell's\nequations with large-scale tight-binding simulations. We find that hot-carrier\nproperties depend sensitively on the alloy composition. Specifically,\nnanoparticles with a large gold fraction produce hot carriers under visible\nlight illumination while nanoparticles with a large silver fraction require\nhigher photon energies to produce hot carriers. Moreover, most hot carriers in\nnanoparticles with a large gold fraction originate from interband transitions\nwhich give rise to energetic holes and \"cold\" electrons near the Fermi level.\nIncreasing the silver fraction enhances the generation rate of hot carriers\nfrom intraband transitions which produce energetic electrons and \"cold\" holes.\nThese findings demonstrate that alloy composition is a powerful tuning\nparameter for the design of nanoparticles for applications in solar energy\nconversion and sensing that require precise control of hot-carrier properties."
    },
    {
        "anchor": "Strong feedback and current noise in nanoelectromechanical systems: We demonstrate the feasibility of a strong feedback regime for a\nsingle-electron tunneling device weakly coupled to an underdamped single-mode\noscillator. In this regime, mechanical oscillations are generated and the\ncurrent is strongly modified whereas the current noise is parametrically big\nwith respect to the Poisson value. This regime requires energy dependence of\nthe tunnel amplitudes. For sufficiently fast tunnel rates the mechanical\ncontribution to current noise can exceed the Poisson value even beyond the\nstrong feedback regime.",
        "positive": "Anderson localization and the topology of classifying spaces: We construct the generic phase diagrams encoding the topologically distinct\nlocalized and delocalized phases of noninteracting fermionic quasiparticles for\nany symmetry class from the tenfold way in one, two, and three dimensions. To\nthis end, we start from a massive Dirac Hamiltonian perturbed by a generic\ndisorder for any dimension of space and for any one of the ten symmetry classes\nfrom the tenfold way. The physics of Anderson localization is then encoded by a\ntwo-dimensional phase diagram that we deduce from the topology of the space of\nnormalized Dirac masses. This approach agrees with previously known results and\ngives an alternative explanation for the even-odd effect in the one-dimensional\nchiral symmetry classes. We also give a qualitative explanation for the Gade\nsingularity and Griffiths effects in the density of states using the first\nhomotopy group of the normalized Dirac masses in two dimensions. Finally, this\napproach is used to analyze the stability of massless Dirac fermions on the\nsurface of three-dimensional topological crystalline insulators."
    },
    {
        "anchor": "Effects of interaction on field-induced resonances in confined Fermi\n  liquid: We consider the two-dimensional electron gas confined laterally to a narrow\nchannel by a harmonic potential. As the Zeeman splitting matches the\nintersubband separation the nonlocal spin polarization develops a minimum as\nreported by Frolov et al. [Nature (London) 458, 868 (2009)]. This phenomenon\ntermed Ballistic Spin Resonance is due to the degeneracy between the nearest\noppositely polarized subbands that is lifted by spin-orbit coupling. We showed\nthat the resonance survives the weak and short-range interaction. The latter\ndetunes it and as a result shifts the Zeeman splitting at which the minimum in\nspin polarization occurs. Here this shift is attributed to the absence of Kohn\ntheorem for the spin sloshing collective mode. We characterized the shift due\nto weak interaction qualitatively by analyzing the spin sloshing mode within\nthe Fermi liquid phenomenology.",
        "positive": "Generation of Spin Entanglement in Nonequilibrium Quantum Dots: We propose schemes for generating spatially-separated spin entanglement in\nsystems of two quantum dots with onsite Coulomb repulsion weakly coupled to a\njoint electron reservoir. An enhanced probability for the formation of spin\nentanglement is found in nonequilibrium situations with one extra electron on\neach dot, either in the transient state after rapid changes of the gate\nvoltage, or in the steady state with applied bias voltage. In both cases\nso-called Werner states with spin singlet fidelity exceeding 1/2 are generated,\nwhich indicates entanglement."
    },
    {
        "anchor": "Layer Antiferromagnetic State in Bilayer Graphene : A First-Principle\n  Investigation: The ground state of bilayer graphene is investigated by the density\nfunctional calculations with local spin density approximation. We find a ground\nstate with layer antiferromagnetic ordering, which has been suggested by former\nstudies based on simplified model. The calculations prove that the layer\nantiferromagnetic state (LAF) is stable even if the remote hopping and nonlocal\nCoulomb interaction are included. The gap of the LAF state is about 1.8 meV,\ncomparable to the experimental value. The surface magnetism in BLG is of the\norder of $10^{-2} \\mu_B /nm^2 $.",
        "positive": "Negative longitudinal magnetoresistance from anomalous N=0 Landau level\n  in topological materials: Negative longitudinal magnetoresistance (NLMR) is shown to occur in\ntopological materials in the extreme quantum limit, when a magnetic field is\napplied parallel to the excitation current. We perform pulsed and DC field\nmeasurements on Pb1-xSnxSe epilayers where the topological state can be\nchemically tuned. The NLMR is observed in the topological state, but is\nsuppressed and becomes positive when the system becomes trivial. In a\ntopological material, the lowest N=0 conduction Landau level disperses down in\nenergy as a function of increasing magnetic field, while the N=0 valence Landau\nlevel disperses upwards. This anomalous behavior is shown to be responsible for\nthe observed NLMR. Our work provides an explanation of the outstanding question\nof NLMR in topological insulators and establishes this effect as a possible\nhallmark of bulk conduction in topological matter."
    },
    {
        "anchor": "The Casimir effect for a stack of conductive planes: The Casimir interaction in a stack of equally spaced infinitely thin layers\nis investigated within the zero-frequency mode summation method. The response\nproperties are considered to be described by a constant conductivity or by a\nDrude-Lorentz model with a finite set of oscillators consistent with the\noptical characteristics for graphite. It is found that the asymptotic distance\ndependence is affected significantly by the specific response. While the energy\nis $\\sim 1/d^3$ for the constant conductivity model, the energy exhibits\nfractional dependence $\\sim 1/d^{5/2}$ for the Drude-Lorentz description. The\nCasimir force on a plane is also strongly dependent upon the particular plane\nlocation in the stack. Furthermore, the calculated Casimir energy within the\nDrude-Lorentz model yields results in good agreement with measured cohesion\nenergy in graphite.",
        "positive": "Boundary spin polarization as robust signature of topological phase\n  transition in Majorana nanowires: We show that the boundary charge and spin can be used as alternative\nsignatures of the topological phase transition in topological models such as\nsemiconducting nanowires with strong Rashba spin-orbit interaction in the\npresence of a magnetic field and in proximity to an $s$-wave superconductor. We\nidentify signatures of the topological phase transition that do not rely on the\npresence of Majorana zero-energy modes and, thus, can serve as independent\nprobes of topological properties. The boundary spin component along the\nmagnetic field, obtained by summing contributions from all states below the\nFermi level, has a pronounced peak at the topological phase transition point.\nGenerally, such signatures can be observed at boundaries between topological\nand trivial sections in nanowires and are stable against disorder."
    },
    {
        "anchor": "Electrically Active Domain Wall Magnons in Layered van der Waals\n  Antiferromagnets: We study theoretically domain wall (DW) magnons-elementary collective\nexcitations of magnetic DWs -- in easy-axis layered van der Waals (vdW)\nantiferromagnets, where they behave as normal modes of coupled spin\nsuperfluids. We uncover that, due to spin-charge coupling in vdW magnets, such\nDW magnons can be activated by voltage-induced torques, thereby providing a\npath for their low-dissipation and nanoscale excitation. Moreover, the\nelectrical activation and the number of DW magnons at a frequency can be\ncontrolled by applying symmetry-breaking static magnetic field, adding\ntunability of signal transmission by them. Our results highlight that domain\nwalls in vdW magnets provide a promising platform to route coherent spin\ninformation for a broad range of explorations in spintronics and magnetism.",
        "positive": "Topology of multipartite non-Hermitian one-dimensional systems: The multipartite non-Hermitian Su-Schrieffer-Heeger model is explored as a\nprototypical example of one-dimensional systems with several sublattice sites\nfor unveiling intriguing insulating and metallic phases with no Hermitian\ncounterparts. These phases are characterized by composite cyclic loops of\nmultiple complex-energy bands encircling single or multiple exceptional points\n(EPs) on the parametric space of real and imaginary energy. We show the\ntopology of these composite loops is similar to well-known topological objects\nlike M\\\"obius strips and Penrose triangles, and can be quantified by a\nnonadiabatic cyclic geometric phase which includes contributions only from the\nparticipating bands. We analytically derive a complete phase diagram with the\nphase boundaries of the model. We further examine the connection between the\nencircling of multiple EPs by complex-energy bands on parametric space and\nassociated topology."
    },
    {
        "anchor": "Effects of random domains on the zero Hall plateau in quantum anomalous\n  Hall effect: Recently, a zero Hall conductance plateau with random domains is\nexperimentally observed in quantum anomalous Hall (QAH) effect. We study the\neffects of random domains on the zero Hall plateau in QAH insulators. We find\nthe structure inversion symmetry determines the scaling property of the zero\nHall plateau transition in the QAH systems. In the presence of structure\ninversion symmetry, the zero Hall plateau state shows a quantum-Hall-type\ncritical point, originating from the two decoupled subsystems with opposite\nChern numbers. However, the absence of structure inversion symmetry leads to\nmixture between these two subsystems, gives rise to a line of critical points,\nand dramatically changes the scaling behavior. Hereinto, we predict a\nBerezinskii-Kosterlitz-Thouless-type transition during the Hall conductance\nplateau switching in the QAH insulators. Our results are instructive for both\ntheoretic understanding of the zero Hall plateau transition and future\ntransport experiments in the QAH insulators.",
        "positive": "Kondo impurities in nanoscopic systems: new confinement-induced regimes: We present results for Kondo impurities in nanoscopic systems. Using exact\ndiagonalization in small clusters and Wilson's renormalization group we analyze\nan isolated system and a nanoscopic system weakly coupled to a macroscopic\nreservoir. In the latter case, new regimes not observed in macroscopic\nhomogeneous systems are induced by the confinement of conduction electrons.\nThese new confinement-induced regimes are very different depending on whether\nthe Fermi energy coincides with the energy of a resonant state or lies between\ntwo quasi-bound states."
    },
    {
        "anchor": "Born Oppenheimer Dynamics Near Metal Surfaces: We discuss the usefulness of Born-Oppenheimer potential surfaces for nuclear\ndynamics for molecules strongly coupled to metal surfaces. A simple model\ndemonstrating the construction of such surface for a molecular junction is\ndiscussed.",
        "positive": "Spin dynamics of hot excitons in diluted magnetic semiconductors with\n  spin-orbit interaction: We explore the impact of a Rashba-type spin-orbit interaction in the\nconduction band on the spin dynamics of hot excitons in diluted magnetic\nsemiconductor quantum wells. In materials with strong spin-orbit coupling, we\nidentify parameter regimes where spin-orbit effects greatly accelerate the spin\ndecay and even change the dynamics qualitatively in the form of damped\noscillations. Furthermore, we show that the application of a small external\nmagnetic field can be used to either mitigate the influence of spin-orbit\ncoupling or entirely remove its effects for fields above a material-dependent\nthreshold."
    },
    {
        "anchor": "Dynamic Coulomb blockade in single-lead quantum dots: We investigate transient dynamic response of an Anderson impurity quantum dot\nto a family of ramp-up driving voltage applied to the single coupling lead.\nTransient current is calculated based on a hierarchical equations of motion\nformalism for open dissipative systems [J. Chem. Phys. 128, 234703 (2008)]. In\nthe nonlinear response and nonadiabatic charging regime, characteristic\nresonance features of transient response current reveal distinctly and\nfaithfully the energetic configuration of the quantum dot. We also discuss and\ncomment on both the physical and numerical aspects of the theoretical formalism\nused in this work.",
        "positive": "Electromagnetic and thermal responses of Z topological insulators and\n  superconductors in odd spatial dimensions: The relation between bulk topological invariants and experimentally\nobservable physical quantities is a fundamental property of topological\ninsulators and superconductors. In the case of chiral symmetric systems in odd\nspatial dimensions such as time-reversal invariant topological superconductors\nand topological insulators with sublattice symmetry, this relation has not been\nwell understood. We clarify that the winding number which characterizes the\nbulk Z non-triviality of these systems can appear in electromagnetic and\nthermal responses in a certain class of heterostructure systems. It is also\nfound that the Z non-triviality can be detected in the bulk \"chiral\npolarization\", which is induced by magnetoelectric effects."
    },
    {
        "anchor": "Room temperature nonlocal detection of charge-spin interconversion in a\n  topological insulator: Topological insulators (TIs) are emerging materials for next-generation\nlow-power nanoelectronic and spintronic device applications. TIs possess\nnon-trivial spin-momentum locking features in the topological surface states in\naddition to the spin-Hall effect (SHE), and Rashba states due to high\nspin-orbit coupling (SOC) properties. These phenomena are vital for observing\nthe charge-spin conversion (CSC) processes for spin-based memory, logic and\nquantum technologies. Although CSC has been observed in TIs by potentiometric\nmeasurements, reliable nonlocal detection has so far been limited to cryogenic\ntemperatures up to T = 15 K. Here, we report nonlocal detection of CSC and its\ninverse effect in the TI compound Bi1.5Sb0.5Te1.7Se1.3 at room temperature\nusing a van der Waals heterostructure with a graphene spin-valve device. The\nlateral nonlocal device design with graphene allows observation of both\nspin-switch and Hanle spin precession signals for generation, injection and\ndetection of spin currents by the TI. Detailed bias- and gate-dependent\nmeasurements in different geometries prove the robustness of the CSC effects in\nthe TI. These findings demonstrate the possibility of using topological\nmaterials to make all-electrical room-temperature spintronic devices.",
        "positive": "Anisotropic strain effects in small-twist-angle graphene on graphite: The direct experimental probing of locally varying lattice parameters and\nanisotropic lattice deformations in atomic multilayers is extremely\nchallenging. Here, we develop a new combined numerical/graphical method for the\nanalysis of irregular moir\\'e superstructures measured by scanning tunneling\nmicroscopy (STM) on a small-twist-angle ($\\sim$0.6$^{\\circ}$) graphene on\nhighly oriented pyrolytic graphite (gr/HOPG). We observe distorted moir\\'e\npatterns with a spatially varying period in annealed gr/HOPG. The nanoscale\nmodulation of the moir\\'e period observed by STM reflects a locally strained\n(and sheared) graphene with anisotropic variation of the lattice parameters. We\nuse a specific algorithm based on a rigid lattice Fourier method, which is able\nto reconstruct the irregular and distorted moir\\'e patterns emerging from\nstrain-induced lattice deformations. Our model is universal and can be used to\nstudy different moir\\'e patterns occurring in two-dimensional van der Waals\nheterostructures. Additionally, room temperature scanning tunneling\nspectroscopy measurements show electronic states at the Dirac point, localized\non moir\\'e hills, which increase significantly the apparent corrugation of the\nmoir\\'e pattern. The measured topography is compared to classical molecular\ndynamics simulations. Density functional theory (DFT) calculations confirm that\nan AAB stacked trilayer region itself can contribute electronic states near the\nFermi-level, in agreement with the measured peak in the local density of\nstates. Furthermore, CMD calculations reveal direction-dependent bond\nalternations ($\\sim$0.5$\\%$) around the stacking regions, induced by shear\nstrain, which could influence electronic properties."
    },
    {
        "anchor": "Nonlinear shot noise in mesoscopic diffusive normal-superconducting\n  systems: We study differential shot noise in mesoscopic diffusive\nnormal-superconducting (NS) heterostructures at finite voltages where nonlinear\neffects due to the superconducting proximity effect arise. A numerical\nscattering-matrix approach is adopted. Through an NS contact, we observe that\nthe shot noise shows a reentrant dependence on voltage due to the\nsuperconducting proximity effect but the differential Fano factor stays\napproximately constant. Furthermore, we consider differential shot noise in the\nstructures where an insulating barrier is formed between normal and\nsuperconducting regions and calculate the differential Fano factor as a\nfunction of barrier height.",
        "positive": "Counting Statistics of Non-Markovian Quantum Stochastic Processes: We derive a general expression for the cumulant generating function (CGF) of\nnon-Markovian quantum stochastic transport processes. The long-time limit of\nthe CGF is determined by a single dominating pole of the resolvent of the\nmemory kernel from which we extract the zero-frequency cumulants of the current\nusing a recursive scheme. The finite-frequency noise is expressed not only in\nterms of the resolvent, but also initial system-environment correlations. As an\nillustrative example we consider electron transport through a dissipative\ndouble quantum dot for which we study the effects of dissipation on the\nzero-frequency cumulants of high orders and the finite-frequency noise."
    },
    {
        "anchor": "A semi-Dirac point in the Hofstadter spectrum: The spectrum of tight binding electrons on a square lattice with half a\nmagnetic flux quantum per unit cell exhibits two Dirac points at the band\ncenter. We show that, in the presence of an additional uniaxial staggered\npotential, this pair of Dirac points may merge into a single one, with a\ntopological transition towards a gapped phase. At the transition, the spectrum\nis linear in one direction and quadratic in the other one (a spectrum recently\nnamed \"hybrid\" or \"semi-Dirac\"). This transition is studied in the framework of\na general Hamiltonian describing the merging of Dirac points. The possibility\nof creating gauge fields for cold atoms in optical lattices may offer the first\nopportunity to observe this merging of Dirac points and the hybrid dispersion\nrelation.",
        "positive": "Quantifying phonon particle and wave transport in nanostructures--The\n  unexpectedly strong particle effect in silicon nanophononic metamaterial with\n  cross junction: Understanding phonon transport mechanisms in nanostructures is of great\nimportance for delicately tailoring thermal properties. Combining phonon\nparticle and wave effects through different strategies, previous studies have\nobtained ultra-low thermal conductivity in nanostructures. However, phonon\nparticle and wave effects are coupled together, that is their individual\ncontributions to phonon transport cannot be figured out. Here, we present how\nto quantify the particle and wave effects on phonon transport by combining\nMonte Carlo and atomic green function methods. We apply it to 1D silicon\nnanophononic metamaterial with cross-junctions, where it has been thought that\nthe wave effect was the main modulator to block phonon transport and the\nparticle effect was negligibly weak. Surprisingly, we find that the particle\neffect is quite significant as well and can contribute as much as 39% to the\ntotal thermal conductivity reduction. Moreover, the particle effect does not\ndecrease much as the cross section area (CSA) of the structure decreases and\nstill keeps quite strong even for CSA as small as 2.23 nm2. Further phonon\ntransmission analysis by reducing the junction leg length also qualitatively\ndemonstrates the strong particle effect. The results highlight the importance\nof mutually controlling particle and wave characteristics, and the\nmethodologies for quantifying phonon particle and wave effect are important for\nphonon engineering by nanostructuring."
    },
    {
        "anchor": "Strong Photothermoelectric Response and Contact Reactivity of the Dirac\n  Semimetal ZrTe5: The family of three-dimensional topological insulators opens new avenues to\ndiscover novel photophysics and to develop novel types of photodetectors. ZrTe5\nhas been shown to be a Dirac semimetal possessing unique topological electronic\nand optical properties. Here we present spatially-resolved photocurrent\nmeasurements on devices made of nanoplatelets of ZrTe5, demonstrating the\nphotothermoelectric origin of the photoresponse. Due to the high electrical\nconductivity and good Seebeck coefficient, we obtain noise-equivalent powers as\nlow as 42 pW/Hz1/2 at room temperature for visible light illumination at zero\nbias. We also show that these devices suffer from significant ambient\nreactivity such as the formation of a Te-rich surface region driven by Zr\noxidation, as well as severe reactions with the metal contacts. This reactivity\nresults in significant stresses in the devices, leading to unusual geometries\nthat are useful for gaining insight into the photocurrent mechanisms. Our\nresults indicate that both the large photothermoelectric response and\nreactivity must be considered when designing or interpreting photocurrent\nmeasurements in these systems.",
        "positive": "Theory of topological spin Josephson junctions: We study the spin transport through a 1D quantum Ising-XY-Ising spin link\nthat emulates a topological superconducting-normal-superconducting structure\nvia Jordan-Wigner (JW) transformation. We calculate, both analytically and\nnumerically, the spectrum of spin Andreev bound states and the resulting\n$\\mathbb{Z}_2$ fractional spin Josephson effect (JE) pertaining to the emerging\nMajorana JW fermions. Deep in the topological regime, we identify an effective\ntime-reversal symmetry that leads to $\\mathbb{Z}_4$ fractional spin JE in the\n$\\textit{presence}$ of interactions within the junction. Moreover, we uncover a\nhidden inversion time-reversal symmetry that protects the $\\mathbb{Z}_4$\nperiodicity in chains with an odd number of spins, even in the\n$\\textit{absence}$ of interactions. We also analyze the entanglement between\npairs of spins by evaluating the concurrence in the presence of spin current\nand highlight the effects of the JW Majorana states. We propose to use a\nmicrowave cavity setup for detecting the aforementioned JEs by dispersive\nreadout methods and show that, surprisingly, the $\\mathbb{Z}_2$ periodicity is\nimmune to $\\textit{any}$ local magnetic perturbations. Our results are relevant\nfor a plethora of spin systems, such as trapped ions, photonic lattices,\nelectron spins in quantum dots, or magnetic impurities on surfaces."
    },
    {
        "anchor": "Structural symmetry-breaking to explain radiative Auger transitions in\n  self-assembled quantum dots: The optical spectrum of a quantum dot is typically dominated by the\nfundamental transition between the lowest-energy configurations. However, the\nradiative Auger process can result in additional red-shifted emission lines.\nThe origin of these lines is a combination of Coulomb interaction and\nsymmetry-breaking in the quantum dot. In this paper, we present measurements of\nsuch radiative Auger lines for a range of InGaAs/GaAs self-assembled quantum\ndots and use a tight-binding model with a configuration interaction approach to\nexplain their appearance. Introducing a composition fluctuation cluster in the\ndot, our calculations show excellent agreement with measurements. We relate our\nfindings to group theory explaining the origin of the additional emission\nlines. Our model and results give insight into the interplay between the\nsymmetry breaking in a quantum dot and the position and strength of the\nradiative Auger lines.",
        "positive": "Purified graphite surface and vacancy states: undercoordination-induced\n  quantum trap depression and lone pi-electron polarization: We present a simple approach for purifying graphite surface and vacancy\nstates using an angle-resolved x-ray photoelectron residual spectroscopy (XPS).\nComplementing the discoveries of Ugeda et al [Phys Rev Lett 104, 096804\n(2010)], outcomes conform the BOLS theory [Sun, Prog Solid State Chem 35, 1-159\n(2007)] expectation and the recent findings that the shorter and stronger bonds\nbetween undercoordinated atoms induce local strain and quantum potential\ndepression with an association of local densification of energy and core\nelectrons. The shorter atomic distance and the densely and deeply trapped\nbonding and core charges polarize in turn the unpaired pi-electrons nearby\nvacancy, giving rise to the high protrusions and the Dirac EF states as\nobserved. The quantum trap depression and the screening due to the polarized EF\nstates split the crystal potential and hence the extra XPRS C 1s states."
    },
    {
        "anchor": "Electron-phonon interaction and electronic correlations in transport\n  through electrostatically and tunnel coupled quantum dots: We investigate two equivalent capacitively and tunnel coupled quantum dots,\neach coupled to its own pair of leads. Local Holstein type electron-phonon\ncoupling at the dots is assumed. To study many-body effects we use the finite-U\nmean-field slave boson approach. For vanishing interdot interaction, weak e-ph\ncoupling and finite tunneling, molecular orbital spin Kondo effects occur for\nsingle electron or single hole occupations. Phonons influence both correlations\nand tunneling and additionally they shift the energies of the dots. Depending\non the dot energies and the strength of electron-phonon coupling, the system is\noccupied by a different number of electrons that effectively interact with each\nother repulsively or attractively leading to a number of different ground\nstates of DQD. Among them are Kondo-like states with spin, orbital or charge\ncorrelations resulting from polaron cotunneling processes and states with\nmagnetic intersite correlations.",
        "positive": "Dissipation Dynamics Driven Transitions of the Density Matrix Topology: The dynamical evolution of an open quantum system can be governed by the\nLindblad equation of the density matrix. In this letter, we propose that the\ndensity matrix topology can undergo a transition during the Lindbladian\ndynamical evolution. Here we characterize the density matrix topology by the\ntopological invariant of its modular Hamiltonian. We focus on the fermionic\nGaussian state, where the modular Hamiltonian is a quadratic operator of a set\nof fermionic operators. The topological classification of such Hamiltonians\ndepends on their symmetry classes. Hence, a primary issue we deal with in this\nwork is to determine the requirement for the Lindbladian operators, under which\nthe modular Hamiltonian can maintain its symmetry class during the dynamical\nevolution. When these conditions are satisfied, along with a nontrivial\ntopological classification of the symmetry class of the modular Hamiltonian, a\ntopological transition can occur as time evolves. We present two examples of\ndissipation driven topological transitions where the modular Hamiltonian lies\nin the AIII class with U(1) symmetry and in the DIII class without U(1)\nsymmetry, respectively. As a manifestation of the topological transition, we\npresent the signature of the eigenvalues of the density matrix at the\ntransition point."
    },
    {
        "anchor": "Quantum limit for nuclear spin polarization in semiconductor quantum\n  dots: A recent experiment [E. A. Chekhovich et al., Phys. Rev. Lett. 104, 066804\n(2010)] has demonstrated that high nuclear spin polarization can be achieved in\nself-assembled quantum dots by exploiting an optically forbidden transition\nbetween a heavy hole and a trion state. However, a fully polarized state is not\nachieved as expected from a classical rate equation. Here, we theoretically\ninvestigate this problem with the help of a quantum master equation and we\ndemonstrate that a fully polarized state cannot be achieved due to formation of\na nuclear dark state. Moreover, we show that the maximal degree of polarization\ndepends on structural properties of the quantum dot.",
        "positive": "Hydrodynamic collective modes in graphene: Collective behavior is one of the most intriguing aspects of the hydrodynamic\napproach to electronic transport. Here we provide a consistent, unified\ncalculation of the dispersion relations of the hydrodynamic collective modes in\ngraphene. Taking into account viscous effects, we show that the hydrodynamic\nsound mode in graphene becomes overdamped at sufficiently large momentum\nscales. Extending the linearized theory beyond the hydrodynamic regime, we\nconnect the diffusive hydrodynamic charge density fluctuations with plasmons."
    },
    {
        "anchor": "Capacitance, Charge Fluctuations and Dephasing In Coulomb Coupled\n  Conductors: The charge fluctuations of two nearby mesoscopic conductors coupled only via\nthe long range Coulomb force are discussed and used to find the dephasing rate\nwhich one conductor exerts on the other. The discussion is based on a\nformulation of the scattering approach for charge densities and the density\nresponse to a fluctuating potential. Coupling to the Poisson equation results\nin an electrically self-consistent description of charge fluctuations. At\nequilibrium the low-frequency noise power can be expressed with the help of a\ncharge relaxation resistance (which together with the capacitance determines\nthe RC-time of the structure). In the presence of transport the low frequency\ncharge noise power is determined by a resistance which reflects the presence of\nshot noise. We use these results to derive expressions for the dephasing rates\nof Coulomb coupled conductors and to find a self-consistent expression for the\nmeasurement time.",
        "positive": "Magnon Thermal Edelstein Effect Detected by Inverse Spin Hall Effect: In an easy-plane antiferromagnet with the Dzyaloshinskii-Moriya interaction\n(DMI), magnons are subject to an effective spin-momentum locking. An in-plane\ntemperature gradient can generate interfacial accumulation of magnons with a\nspecified polarization, realizing the magnon thermal Edelstein effect. We\ntheoretically investigate the injection and detection of this thermally-driven\nspin polarization in an adjacent heavy metal with strong spin Hall effect. We\nfind that the inverse spin Hall voltage depends monotonically on both\ntemperature and the DMI but non-monotonically on the hard-axis anisotropy.\nCounterintuitively, the magnon thermal Edelstein effect is an even function of\na magnetic field applied along the N\\'eel vector."
    },
    {
        "anchor": "Two-electron dephasing in single Si and GaAs quantum dots: We study the dephasing of two-electron states in a single quantum dot in both\nGaAs and Si. We investigate dephasing induced by electron-phonon coupling and\nby charge noise analytically for pure orbital excitations in GaAs and Si, as\nwell as for pure valley excitations in Si. In GaAs, polar optical phonons give\nrise to the most important contribution, leading to a typical dephasing rate of\n~5.9 GHz. For Si, intervalley optical phonons lead to a typical dephasing rate\nof ~140 kHz for orbital excitations and ~1.1 MHz for valley excitations. For\nharmonic, disorder-free quantum dots, charge noise is highly suppressed for\nboth orbital and valley excitations, since neither has an appreciable dipole\nmoment to couple to electric field variations from charge fluctuators. However,\nboth anharmonicity and disorder break the symmetry of the system, which can\nlead to increased dipole moments and therefore faster dephasing rates.",
        "positive": "Long-range entanglement for spin qubits via quantum Hall edge modes: We propose and analyse a scheme for performing a long-range entangling gate\nfor qubits encoded in electron spins trapped in semiconductor quantum dots. Our\ncoupling makes use of an electrostatic interaction between the state-dependent\ncharge configurations of a singlet-triplet qubit and the edge modes of a\nquantum Hall droplet. We show that distant singlet-triplet qubits can be\nselectively coupled, with gate times that can be much shorter than qubit\ndephasing times and faster than decoherence due to coupling to the edge modes.\nBased on parameters from recent experiments, we argue that fidelities above 99%\ncould in principle be achieved for a two-qubit entangling gate taking as little\nas 20 ns."
    },
    {
        "anchor": "Thermal resistance from non-equilibrium phonons at Si-Ge interface: As nanostructured devices become prevalent, interfaces often play an\nimportant role in thermal transport phenomena. However, interfacial thermal\ntransport remains poorly understood due to complex physics across a wide range\nof length scales from atomistic to microscale. Past studies on interfacial\nthermal resistance have focused on interface-phonon scattering at the atomistic\nscale but overlooked the complex interplay of phonon-interface and\nphonon-phonon scattering at microscale. Here, we use the Peierls-Boltzmann\ntransport equation to show that the resistance from the phonon-phonon\nscattering of non-equilibrium phonons near a Si-Ge interface is much larger\nthan that directly caused by the interface scattering. We report that\nnon-equilibrium in phonon distribution leads to significant entropy generation\nand thermal resistance upon three-phonon scattering by the Boltzmann's\nH-theorem. The physical origin of non-equilibrium phonons in Ge is explained\nwith the mismatch of phonon dispersion, density-of-states, and group velocity,\nwhich serve as general guidance for estimating the non-equilibrium effect on\ninterfacial thermal resistance. Our study bridges a gap between atomistic scale\nand less studied microscale phenomena, providing comprehensive understanding of\noverall interfacial thermal transport and the significant role of phonon-phonon\nscattering.",
        "positive": "Topological Electromagnetic Effects and Higher Second Chern Numbers in\n  Four-Dimensional Gapped Phases: Higher-dimensional topological phases play a key role in understanding the\nlower-dimensional topological phases and the related topological responses\nthrough a dimensional reduction procedure. In this work, we present a\nDirac-type model of four-dimensional (4D) $\\mathbb{Z}_2$ topological insulator\n(TI) protected by $\\mathcal{CP}$-symmetry, whose 3D boundary supports an odd\nnumber of Dirac cones. A specific perturbation splits each bulk massive Dirac\ncone into two valleys separated in energy-momentum space with opposite second\nChern numbers, in which the 3D boundary modes become a nodal sphere or a Weyl\nsemimetallic phase. By introducing the electromagnetic (EM) and pseudo-EM\nfields, exotic topological responses of our 4D system are revealed, which are\nfound to be described by the (4+1)D mixed Chern-Simons theories in the\nlow-energy regime. Notably, several topological phase transitions occur from a\n$\\mathcal{CP}$-broken $\\mathbb{Z}_2$ TI to a $\\mathbb{Z}$ TI when the bulk gap\ncloses by giving rise to exotic double-nodal-line/nodal-hyper-torus gapless\nphases. Finally, we propose to probe experimentally these topological effects\nin cold atoms."
    },
    {
        "anchor": "Ultra-thin Topological Insulator Bi2Se3 Nanoribbons Exfoliated by Atomic\n  Force Microscopy: Ultra-thin topological insulator nanostructures, in which coupling between\ntop and bottom surface states takes place, are of great intellectual and\npractical importance. Due to the weak Van der Waals interaction between\nadjacent quintuple layers (QLs), the layered bismuth selenide (Bi2Se3), a\nsingle Dirac-cone topological insulator with a large bulk gap, can be\nexfoliated down to a few QLs. In this paper, we report the first controlled\nmechanical exfoliation of Bi2Se3 nanoribbons (> 50 QLs) by an atomic force\nmicroscope (AFM) tip down to a single QL. Microwave impedance microscopy is\nemployed to map out the local conductivity of such ultra-thin nanoribbons,\nshowing drastic difference in sheet resistance between 1~2 QLs and 4~5 QLs.\nTransport measurement carried out on an exfoliated (\\leq 5 QLs) Bi2Se3 device\nshows non-metallic temperature dependence of resistance, in sharp contrast to\nthe metallic behavior seen in thick (> 50 QLs) ribbons. These AFM-exfoliated\nthin nanoribbons afford interesting candidates for studying the transition from\nquantum spin Hall surface to edge states.",
        "positive": "Anomalous temperature dependence of the dephasing time in mesoscopic\n  Kondo wires: We present measurements of the magnetoconductance of long and narrow quasi\none-dimensional gold wires containing magnetic iron impurities in a temperature\nrange extending from $15 $mK to $4.2 $K. The dephasing rate extracted from the\nweak antilocalisation shows a pronounced plateau in a temperature region of\n$300 $mK - $800 $mK, associated with the phase breaking due to the Kondo\neffect. Below the Kondo temperature the dephasing rate decreases linearly with\ntemperature, in contradiction with standard Fermi-liquid theory. Our data\nsuggest that the formation of a spin glass due to the interactions between the\nmagnetic moments are responsible for the observed anomalous temperature\ndependence."
    },
    {
        "anchor": "Electron fractionalization induced dephasing in Luttinger liquids: Using the appropriate fractionalization mechanism, we correctly derive the\ntemperature (T) and interaction dependence of the electron lifetime $\\tau_F$ in\nLuttinger liquids. For strong enough interactions, we report that\n$(T\\tau_F)\\propto g$, with $g\\ll 1$ being the standard Luttinger exponent; This\nreinforces that electrons are {\\it not} good quasiparticles. We immediately\nemphasize that this is of importance for the detection of electronic\ninterferences in ballistic 1D rings and carbon nanotubes, inducing\n``dephasing'' (strong reduction of Aharonov-Bohm oscillations).",
        "positive": "High-Power Directional Emission from Microlasers with Chaotic Resonators: High-power and highly directional semiconductor cylinder-lasers based on an\noptical resonator with deformed cross section are reported. In the favorable\ndirections of the far-field, a power increase of up to three orders of\nmagnitude over the conventional circularly symmetric lasers was obtained. A\n\"bow-tie\"-shaped resonance is responsible for the improved performance of the\nlasers in the higher range of deformations, in contrast to\n\"whispering-gallery\"-type modes of circular and weakly deformed lasers. This\nresonator design, although demonstrated here in midinfrared quantum-cascade\nlasers, should be applicable to any laser based on semiconductors or other\nhigh-refractive index materials."
    },
    {
        "anchor": "Tunable zero-energy transmission resonances in shifted graphene bilayer: A graphene bilayer is known to perfectly reflect normally incident electrons\ndue to their chirality. This is similar to Klein tunneling, which, in a\nmonolayer, is instead responsible for perfect transmission at normal incidence.\nStacking defaults turn each parabolic band crossing of a bilayer into pairs of\nDirac cones. Here we show that, surprisingly, a stacking default (or shift) in\na bilayer can result in perfect {\\it transmission} at normal incidence as a\nresult of Fabry-P\\'erot type resonances {\\it at zero-energy}. These\nconstructive interferences only happen for a specific orientation of the Dirac\ncones with respect to the incident electron and for quantized values of their\nseparation in reciprocal space. Our results provide a way to control\ntransmission resonances in undoped graphene bilayer structure by adjusting the\nlayer stacking.",
        "positive": "Huge Volume Expansion and Structural Transformation of Carbon Nanotube\n  Aligned Arrays during Electrical Breakdown in Vacuum: We observed a huge volume expansion of aligned single walled carbon nanotube\n(SWNT) arrays accompanied by structural transformation during electrical\nbreakdown in vacuum. The SWNT arrays were assembled between prefabricated Pd\nsource and drain electrodes of 2 \\mu m separation on Si/SiO_2 substrate via\ndielectrophoresis. At high electrical field, the SWNT arrays erupt into large\nmushroom-like structure. Systematic studies with controlled electrical bias\nshow that above a certain field SWNTs swell and transform to nanoparticles and\nflower-like structures with small volume increase. Further increase in\nelectrical bias and repeated sweeping results into amorphous carbon as\ndetermined from scanning and transmission electron microscopy (TEM). Cross\nsectional studies using focused ion beam and TEM show the height of 2-3 nm SWNT\narray increased to about 1 \\mu m with a volume gain of ~ 400 times. The\nelectron energy loss spectroscopy reveals that graphitic sp^2 networks of SWNTs\nare transformed predominantly to sp^3. The current-voltage measurements also\nshow an increase in the resistance of the transformed structure."
    },
    {
        "anchor": "Antiferromagnetism emerging in a ferromagnet with gain: We present a theoretical mapping to show that a ferromagnet with gain (loss)\nis equivalent to an antiferromagnet with an equal amount of loss (gain). Our\nfinding indicates a novel first-order ferromagnet-antiferromagnet phase\ntransition by tuning the gain-loss parameter. As an appealing application, we\ndemonstrate the realization as well as the manipulation of the\nantiferromagnetic skyrmion, a stable topological quasiparticle not yet observed\nexperimentally, in a chiral ferromagnetic thin film with gain. We also consider\nferromagnetic bilayers with balanced gain and loss, and show that the\nantiferromagnetic skyrmion can be found only in the cases with broken\nparity-time symmetry phase. Our results pave a way for investigating the\nemerging antiferromagnetic spintronics and parity-time symmetric magnonics in\nferromagnets.",
        "positive": "Quantum Kinetic Theory of Nonlinear Nernst Effect: For a long period of time, we have been seeking how Berry curvature influnces\nthe transport properties in materials breaking time-reversal symmetry. In\ntime-reversal symmetric material, there will be no thermoelectric current\ninduced by Berry curvature in linear regime. However, the nonlinear Hall\ncurrent can be shown in non-magnetic and non-centrosymmetric materials, where\nBerry curvature dipole plays an important role. Most studies are developed from\nsemi-classical Boltzmann equation. Here we show the quantum kinetic theory for\nnonlinear Nernst effect and introduce a new type of Berry curvature dipole:\nthermoelectric Berry curvature dipole. This new Berry curvature dipole will\nalso induce the thermoelectric transport in nonlinear regime even in\ntime-reversal invariant crystals. We will also apply our theory to topological\ncrystalline insulator with tilted Dirac cone."
    },
    {
        "anchor": "Kinetic properties of the two-dimensional conducting system formed by\n  CrSi2 nanocrystallites in plane (111) of silicon: The behaviors of resistance, magnetoresistance (up to 5 T), and Hall\nelectromotive force (EMF) with varying temperature (from 10 to 300 K) and\nmeasuring current (from 10 mkA to 10 mA) are studied for the Si sample with\nCrSi2 nanocrystallites (NC) in the plane (111). The conduction in such\nheterostructure proceeds in the plane with the NC and is the conduction of a\ntwo-dimensional system of charge carriers that shows some unusual effects. The\ntemperature variation of resistivitymaybe treated as the result of the effect\nof thermal activation but in this case it is characterized by a low activation\nenergy different in value in different temperature ranges. This suggests that\nthe mechanism of conduction is more complex. It is found that the conduction is\ndetermined by the effect of temperature variation not only on carrier\nconcentration but also on its mobility. Magnetoresistivity is also of different\nshape in different temperature ranges. All the above features are treated in\nterms of the proposed model of electron hopping through the conduction band (or\nhole hopping through the valence band). A peculiar effect of giant reduction in\nresistivity with increasing the measuring current has been revealed. Discussed\nare some possible factors responsible for this effect.",
        "positive": "Current induced torques in structures with ultra-thin IrMn\n  antiferromagnet: Relativistic current induced torques and devices utilizing antiferromagnets\nhave been independently considered as two promising new directions in\nspintronics research. Here we report electrical measurements of the torques in\nstructures comprising a $\\sim1$~nm thick layer of an antiferromagnet IrMn. The\nreduced N\\'eel temperature and the thickness comparable to the spin-diffusion\nlength allow us to investigate the role of the antiferromagnetic order in the\nultra-thin IrMn films in the observed torques. In a Ta/IrMn/CoFeB structure,\nIrMn in the high-temperature phase diminishes the torque in the CoFeB\nferromagnet. At low temperatures, the antidamping torque in CoFeB flips sign as\ncompared to the reference Ta/CoFeB structure, suggesting that IrMn in the\nantiferromagnetic phase governs the net torque acting on the ferromagnet. At\nlow temperatures, current induced torque signatures are observed also in a\nTa/IrMn structure comprising no ferromagnetic layer."
    },
    {
        "anchor": "High-frequency Expansion for Floquet Prethermal Phases with Emergent\n  Symmetries: Application to Time Crystals and Floquet Engineering: Prethermalization, where quasi-steady states are realized in the intermediate\nlong time regime (prethermal regime), in periodically driven (Floquet) systems\nis an important phenomenon since it provides a platform of nontrivial Floquet\nmany-body physics. In this Letter, we consider Floquet systems with dual energy\nscales: the Hamiltonian consists of two different terms whose amplitude is\neither comparable or much smaller than the frequency. As a result, when the\nlarger-amplitude drive induces a $\\mathbb{Z}_N$ symmetry operation, we obtain\nthe effective static Hamiltonian respecting a new emergent $\\mathbb{Z}_N$\nsymmetry in high frequency expansions, which describes the dynamics of such\nFloquet systems in the prethermal regime. As an application of our formulation,\nwe consider prethermal discrete time crystals, in which our formalism gives a\ngeneral way to analyze them in the prethermal regime in terms of the static\neffective Hamiltonian. We also provide an application to Floquet engineering,\nwith which we can perform simultaneous control of phases and symmetries of the\nsystems. This enables us to control symmetry protected topological phases even\nwhen the original system does not respect the symmetry.",
        "positive": "Unconventional Topological Insulators from Extended Topological Band\n  Degeneracies: A general and beautiful picture for the realization of topological insulators\nis that the mass term of the Dirac model has a nodal surface wrapping one Dirac\npoint. We show that this geometric picture based on Dirac points can be\ngeneralized to extended band degeneracies with nontrivial topological charges.\nAs the nontrivial topological charges force the extended band degeneracies to\nbe created or annihilated in pairs, when the nodal surface of mass wraps one\nsuch extended band degeneracy, the resulting gapped phase must be topologically\nnontrivial since it cannot adiabatically be deformed into a topologically\ntrivial atomic insulator without closing the energy gap. We use nodal lines\ncarrying a nontrivial $Z_{2}$ monopole charge in three dimensions to illustrate\nthe physics. Notably, because the wrapping surfaces for an extended band\ndegeneracy are diverse, we find that this generalization can bring topological\ninsulators with unconventional pattern of boundary states."
    },
    {
        "anchor": "How To Identify Plasmons from the Optical Response of Nanostructures: A promising trend in plasmonics involves shrinking the size of\nplasmon-supporting structures down to a few nanometers, thus enabling control\nover light-matter interaction at extreme-subwavelength scales. In this limit,\nquantum mechanical effects, such as nonlocal screening and size quantization,\nstrongly affect the plasmonic response, rendering it substantially different\nfrom classical predictions. For very small clusters and molecules, collective\nplasmonic modes are hard to distinguish from other excitations such as\nsingle-electron transitions. Using rigorous quantum mechanical computational\ntechniques for a wide variety of physical systems, we describe how an optical\nresonance of a nanostructure can be classified as either plasmonic or\nnonplasmonic. More precisely, we define a universal metric for such\nclassification, the generalized plasmonicity index (GPI), which can be\nstraightforwardly implemented in any computational electronic-structure method\nor classical electromagnetic approach to discriminate plasmons from\nsingle-particle excitations and photonic modes. Using the GPI, we investigate\nthe plasmonicity of optical resonances in a wide range of systems including:\nthe emergence of plasmonic behavior in small jellium spheres as the size and\nthe number of electrons increase; atomic-scale metallic clusters as a function\nof the number of atoms; and nanostructured graphene as a function of size and\ndoping down to the molecular plasmons in polycyclic aromatic hydrocarbons. Our\nstudy provides a rigorous foundation for the further development of ultrasmall\nnanostructures based on molecular plasmonics",
        "positive": "Mode-Shell correspondence, a unifying theory in topological physics --\n  Part I: Chiral number of zero-modes: We propose a theory, that we call the \\textit{mode-shell correspondence},\nwhich relates the topological zero-modes localised in phase space to a\n\\textit{shell} invariant defined on the surface forming a shell enclosing these\nzero-modes. We show that the mode-shell formalism provides a general framework\nunifying important results of topological physics, such as the bulk-edge\ncorrespondence, higher-order topological insulators, but also the Atiyah-Singer\nand the Callias index theories. In this paper, we discuss the already rich\nphenomenology of chiral symmetric Hamiltonians where the topological quantity\nis the chiral number of zero-dimensionial zero-energy modes. We explain how, in\na lot of cases, the shell-invariant has a semi-classical limit expressed as a\ngeneralised winding number on the shell, which makes it accessible to\nanalytical computations."
    },
    {
        "anchor": "Ultra-low current 10 nm spin Hall nano-oscillators: Nano-constriction based spin Hall nano-oscillators (SHNOs) are at the\nforefront of spintronics research for emerging technological applications such\nas oscillator-based neuromorphic computing and Ising Machines. However, their\nminiaturization to the sub-50 nm width regime results in poor scaling of the\nthreshold current. Here, we show that current shunting through the Si substrate\nis the origin of this problem and study how different seed layers can mitigate\nit. We find that an ultra-thin Al$_{2}$O$_{3}$ seed layer and SiN (200 nm)\ncoated p-Si substrates provide the best improvement, enabling us to scale down\nthe SHNO width to a truly nanoscopic dimension of 10 nm, operating at threshold\ncurrents below 30 $\\mu$A. In addition, the combination of electrical insulation\nand high thermal conductivity of the Al$_{2}$O$_{3}$ seed will offer the best\nconditions for large SHNO arrays, avoiding any significant temperature\ngradients within the array. Our state-of-the-art ultra-low operational current\nSHNOs hence pave an energy-efficient route to scale oscillator-based computing\nto large dynamical neural networks of linear chains or two-dimensional arrays.",
        "positive": "Polarization resolved magneto-Raman scattering of graphene-like domains\n  on natural graphite: The micro-Raman scattering response of a graphene-like location on the\nsurface of bulk natural graphite is investigated both at $T=\\unit{4.2}{K}$ and\nat room temperature in magnetic fields up to 29 T. Two different polarization\nconfigurations, co-circular and crossed-circular, are employed in order to\ndetermine the Raman scattering selection rules. Several distinct series of\nelectronic excitations are observed and we discuss their characteristic shapes\nand amplitudes. In particular, we report a clear splitting of the signals\nassociated with the inter-Landau level excitations $-n\\rightarrow+n$.\nFurthermore, we observe the pronounced interaction of the zone-center\nE$_{\\text{2g}}$-phonon with three different sets of electronic excitations.\nPossible origins for these graphene-like inclusions on the surface of bulk\ngraphite are discussed."
    },
    {
        "anchor": "Effect of phonons on the electron spin resonance absorption spectrum: The unavoidable presence of vibrations in solid-state devices can drastically\nmodify the expected electron spin resonance (ESR) absorption spectrum in\nmagnetically active systems. In this work, we model the effect of phonons and\ntemperature on the ESR signal in molecular systems with strong $E \\otimes e$\nJahn-Teller (JT) effect and an electronic spin-$1/2$. Our microscopic model\nconsiders the linear JT interaction with a continuum of phonon modes, the\nspin-orbit coupling, the Zeeman effect, and the response of the system under a\nweak oscillating magnetic field. We derive a Lindblad master equation for the\norbital and spin degrees of freedom, where one- and two-phonon processes are\nconsidered for the phonon-induced relaxation, and the thermal dependence of Ham\nreduction factors is calculated. We find that the suppression of ESR signals is\ndue to phonon broadening but not based on the common assumption of orbital\nquenching. Our results can be applied to explain the experimentally observed\nabsence of the ESR signal in color centers in diamond, such as the neutral\nnitrogen-vacancy and negatively charged silicon-vacancy color centers in\ndiamond.",
        "positive": "Fast time-domain current measurement for quantum dot charge sensing\n  using a homemade cryogenic transimpedance amplifier: We developed a high-speed and low-noise time-domain current measurement\nscheme using a homemade GaAs high-electron-mobility-transistor-based cryogenic\ntransimpedance amplifier (TIA). The scheme is versatile for broad cryogenic\ncurrent measurements, including semiconductor spin-qubit readout, owing to the\nTIA's having low input impedance comparable to that of commercial\nroom-temperature TIAs. The TIA has a broad frequency bandwidth and a low noise\nfloor, with a trade-off between them governed by the feedback resistance\n$R_{FB}$. A lower $R_{FB}$ of 50 k$\\Omega$ enables high-speed current\nmeasurement with a -3dB cutoff frequency $f_{-3dB}$ = 28 MHz and noise-floor\n$NF = 8.5 \\times 10^{-27}$ A$^{2}$/Hz, while a larger $R_{FB}$ of 400 k$\\Omega$\nprovides low-noise measurement with $NF = 1.0 \\times 10^{-27}$ A$^{2}$/Hz and\n$f_{-3dB}$ = 4.5 MHz. Time-domain measurement of a 2-nA peak-to-peak square\nwave, which mimics the output of the standard spin-qubit readout technique via\ncharge sensing, demonstrates a signal-to-noise ratio (SNR) of 12.7, with the\ntime resolution of 48 ns, for $R_{FB}$ = 200 k$\\Omega$, which compares\nfavorably with the best-reported values for the radio-frequency (RF)\nreflectometry technique. The time resolution can be further improved at the\ncost of the SNR (or vice versa) by using an even smaller (larger) $R_{FB}$,\nwith a further reduction in the noise figure possible by limiting the frequency\nband with a low-pass filter. Our scheme is best suited for readout electronics\nfor cryogenic sensors that require a high time resolution and current\nsensitivity and thus provides a solution for various fundamental research and\nindustrial applications."
    },
    {
        "anchor": "Scattering Theory of Kondo Mirages and Observation of Single Kondo Atom\n  Phase Shift: We explain the origin of the Kondo mirage seen in recent quantum corral\nScanning Tunneling Microscope (STM) experiments with a scattering theory of\nelectrons on the surfaces of metals. Our theory combined with experimental data\nprovides the first direct observation of a single Kondo atom phase shift. The\nKondo mirage at the empty focus of an elliptical quantum corral is shown to\narise from multiple electron bounces off the walls of the corral in a manner\nanalagous to the formation of a real image in optics. We demonstrate our theory\nwith direct quantitive comparision to experimental data.",
        "positive": "Electron trapping and detrapping in an oxide two-dimensional electron\n  gas: The role of ferroelastic twin walls: The choice of electrostatic gating over the conventional chemical doping for\nphase engineering of quantum materials is attributed to the fact that the\nformer can reversibly tune the carrier density without affecting the system's\nlevel of disorder. However, this proposition seems to break down in\nfield-effect transistors involving SrTiO$_3$ (STO) based two-dimensional\nelectron gases. Such peculiar behavior is associated with the electron trapping\nunder an external electric field. However, the microscopic nature of trapping\ncenters remains an open question. In this paper, we investigate electric\nfield-induced charge trapping/detrapping phenomena at the conducting interface\nbetween band insulators $\\gamma$-Al$_2$O$_3$ and STO. Our transport\nmeasurements reveal that the charge trapping under +ve back gate voltage\n($V_g$) above the tetragonal to cubic structural transition temperature ($T_c$)\nof STO is contributed by the electric field-assisted thermal escape of\nelectrons from the quantum well, and the clustering of oxygen vacancies (OVs)\nas well. We observe an additional source of trapping below the $T_c$, which\narises from the trapping of free carriers at the ferroelastic twin walls of\nSTO. Application of -ve $V_g$ results in a charge detrapping, which vanishes\nabove $T_c$ also. This feature demonstrates the crucial role of structural\ndomain walls in the electrical transport properties of STO based\nheterostructures. The number of trapped (detrapped) charges at (from) the twin\nwall is controlled by the net polarity of the wall and is completely reversible\nwith the sweep of $V_g$."
    },
    {
        "anchor": "Two-dimensional plasmons in lateral carbon nanotube network structures\n  and their effect on the terahertz radiation detection: We consider the carrier transport and plasmonic phenomena in the lateral\ncarbon nanotube (CNT) networks forming the device channel with asymmetric\nelectrodes. One electrode is the Ohmic contact to the CNT network and the\nanother contact is the Schottky contact. These structures can serve as\ndetectors of the terahertz (THz) radiation. We develop the device model for\nresponse of the lateral CNT networks which comprise a mixture of randomly\noriented semiconductor CNTs (s-CNTs) and quasi-metal CNTs (m-CNTs). The\nproposed model includes the concept of the two-dimensional plasmons in\nrelatively dense networks of randomly oriented CNTs (CNT \"felt\") and predicts\nthe detector responsivity spectral characteristics. The detection mechanism is\nthe rectification of the ac current due the nonlinearity of the Schottky\ncontact current-voltage characteristics under the conditions of a strong\nenhancement of the potential drop at this contact associated with the plasmon\nexcitation. We demonstrate that the excitation of the two-dimensional plasmons\nby incoming THz radiation the detector responsivity can induce sharp resonant\npeaks of the detector responsivity at the signal frequencies corresponding to\nthe plasmonic resonances. The detector responsivity depends on the fractions of\nthe s- and m-CNTs. The burning of the near-contact regions of the m-CNTs or\ndestruction of these CNTs leads to a marked increase in the responsivity in\nagreement with our experimental data. The resonant THz detectors with\nsufficiently dense lateral CNT networks can compete and surpass other THz\ndetectors using plasmonic effects at room temperatures.",
        "positive": "Spin-resolved Andreev levels and parity crossings in hybrid\n  superconductor-semiconductor nanostructures: The hybrid combination of superconductors and low-dimensional semiconductors\noffers a versatile ground for novel device concepts, such as sources of\nspin-entangled electrons, nanoscale superconducting magnetometers, or recently\nproposed qubits based on topologically protected Majorana fermions. The\nunderlying physics behind such hybrid devices ultimately rely on the magnetic\nproperties of sub-gap excitations, known as Andreev levels. Here we report the\nZeeman effect on the Andreev levels of a semiconductor nanowire quantum dot\n(QD) strongly coupled to a conventional superconductor. The combination of the\nlarge QD g-factor with the large superconductor critical magnetic field allows\nspin degeneracy to be lifted without suppressing superconductivity. We show\nthat a Zeeman-split Andreev level crossing the Fermi energy signals a quantum\nphase transition in the ground state of the superconductivity-induced QD,\ndenoting a change in the fermionic parity of the system. This transition\nmanifests itself as a zero-bias conductance anomaly appearing at a finite\nmagnetic field, with properties that resemble those expected for Majorana\nfermions in a topological superconductor. Although the herein reported\nzero-bias anomalies do not hold any relation with topological\nsuperconductivity, the observed parity transitions can be regarded as\nprecursors of Majorana modes in the long-wire limit."
    },
    {
        "anchor": "Pairing in ultracold Fermi gases in the lowest Landau level: We study a rapidly rotating gas of unpolarized spin-1/2 ultracold fermions in\nthe two-dimensional regime when all atoms reside in the lowest Landau level.\nDue to the presence of the spin degree of freedom both s-wave and p-wave\ninteractions are allowed at ultralow temperatures. We investigate the phase\ndiagram of this system as a function of the filling factor in the lowest Landau\nlevel and in terms of the ratio between s- and p-wave interaction strengths. We\nshow that the presence of attractive interactions induces a wide regime of\nphase separation with formation of maximally compact droplets that are either\nfully polarized or composed of spin-singlets. In the regime with no phase\nseparation, we give evidence for fractional quantum Hall states. Most notably,\nwe find two distinct singlet states at the filling nu =2/3 for different\ninteractions. One of these states is accounted for by the composite fermion\ntheory while the other one is a paired state for which we identify two\ncompeting descriptions with different topological structure. This paired state\nmay be an Abelian liquid of composite spin-singlet Bose molecules with Laughlin\ncorrelations. Alternatively, it may be a known non-Abelian paired state,\nindicated by good overlaps with the corresponding trial wavefunction. By fine\ntuning of the scattering lengths it is possible to create the non-Abelian\ncritical Haldane-Rezayi state for nu =1/2 and the permanent state of Moore and\nRead for nu =1. For purely repulsive interactions, we also find evidence for a\ngapped Halperin state at nu=2/5.",
        "positive": "Dynamics of F=1 87Rb condensates at finite temperatures: We investigate the dynamics of a F=1 spinor Bose-Einstein condensate of 87Rb\natoms confined in a quasi-one-dimensional trap both at zero and at finite\ntemperature. At zero temperature, we observe coherent oscillations between\npopulations of the various spin components and the formation of multiple\ndomains in the condensate. We study also finite temperature effects in the spin\ndynamics taking into account the phase fluctuations in the Bogoliubov-de Gennes\nframework. At finite T, despite complex multidomain formation in the\ncondensate, population equipartition occurs. The length scale of these spin\ndomains seems to be determined intrinsically by nonlinear interactions."
    },
    {
        "anchor": "Quantum Dynamics of the Driven and Dissipative Rabi Model: The Rabi model considers a two-level system (or spin-1/2) coupled to a\nquantized harmonic oscillator and describes the simplest interaction between\nmatter and light. The recent experimental progress in solid-state circuit\nquantum electrodynamics has engendered theoretical efforts to quantitatively\ndescribe the mathematical and physical aspects of the light-matter interaction\nbeyond the rotating wave approximation. We develop a stochastic Schr\\\"{o}dinger\nequation approach which enables us to access the strong-coupling limit of the\nRabi model and study the effects of dissipation, and AC drive in an exact\nmanner. We include the effect of ohmic noise on the non-Markovian spin dynamics\nresulting in Kondo-type correlations, as well as cavity losses. We compute the\ntime evolution of spin variables in various conditions. As a consideration for\nfuture work, we discuss the possibility to reach a steady state with one\npolariton in realistic experimental conditions.",
        "positive": "Comment on Absence of detectable current-induced magneto-optical Kerr\n  effects in Pt, Ta and W Appl. Phys. Lett. 109, 172402 (2016): We recently reported measurements of spin polarization in W and Pt thin films\nproduced by the spin Hall effect (SHE) using a magneto-optic Kerr effect (MOKE)\nsystem based on crossed polarizers that detects changes in light intensity.\nRiego et al used a generalized magneto-optical ellipsometry system that in\nprinciple can distinguish pure optical reflectivity from magneto-optic signals,\nbut were unable to detect SHE polarization in their nominally W, Ta and Pt\nfilms. They argued that our results are spurious and likely due to resistive\nheating which temporally modulates the film temperature and reflectivity, and\nthat any SHE polarization is too small to be detected in metal films. In this\ncomment, we argue that our original results are correct as presented, and\ndiscuss why"
    },
    {
        "anchor": "Commensurability oscillations in the rf conductivity of unidirectional\n  lateral superlattices: measurement of anisotropic conductivity by coplanar\n  waveguide: We have measured the rf magnetoconductivity of unidirectional lateral\nsuperlattices (ULSLs) by detecting the attenuation of microwave through a\ncoplanar waveguide placed on the surface. ULSL samples with the principal axis\nof the modulation perpendicular (S_perp) and parallel (S_||) to the microwave\nelectric field are examined. For low microwave power, we observe expected\nanisotropic behavior of the commensurability oscillations (CO), with CO in\nsamples S_perp and S_|| dominated by the diffusion and the collisional\ncontributions, respectively. Amplitude modulation of the Shubnikov-de Haas\noscillations is observed to be more prominent in sample S_||. The difference\nbetween the two samples is washed out with the increase of the microwave power,\nletting the diffusion contribution govern the CO in both samples. The failure\nof the intended directional selectivity in the conductivity measured with high\nmicrowave power is interpreted in terms of large-angle electron-phonon\nscattering.",
        "positive": "Observation of nonlocal Josephson effect on double InAs nanowires: Short-range coherent coupling of two Josephson junctions (JJs) are predicted\nto generate a supercurrent in one JJ nonlocally modulated by the phase\ndifference in the other. We report on observation of the nonlocal Josephson\neffect on double InAs nanowires as experimental evidence of the coherent\ncoupling. We measured one JJ sharing one superconducting electrode with the\nother JJ and observed switching current oscillation as a control of the\nnonlocal phase difference. Our result is an important step toward engineering\nof novel superconducting phenomena with the short-range coherent coupling."
    },
    {
        "anchor": "Can the trace formula describe weak localisation?: We attempt to systematically derive perturbative quantum corrections to the\nBerry diagonal approximation of the two-level correlation function (TLCF) for\nchaotic systems. To this end, we develop a ``weak diagonal approximation''\nbased on a recent description of the first weak localisation correction to\nconductance in terms of the Gutzwiller trace formula. This semiclassical method\nis tested by using it to derive the weak localisation corrections to the TLCF\nfor a semiclassically disordered system. Unfortunately the method is unable to\ncorrectly reproduce the ``Hikami boxes'' (the relatively small regions where\nclassical paths are glued together by quantum processes). This results in the\nmethod failing to reproduce the well known weak localisation expansion. It so\nhappens that for the first order correction it merely produces the wrong\nprefactor. However for the second order correction, it is unable to reproduce\ncertain contributions, and leads to a result which is of a different form to\nthe standard one.",
        "positive": "The effects of interactions and disorder in the two-dimensional chiral\n  metal: We study the two-dimensional chiral metal, which is formed at the surface of\na layered three-dimensional system exhibiting the integer quantum Hall effect\nby hybridization of the edge states associated with each layer of the sample.\nWe investigate mesoscopic fluctuations, dynamical screening and inelastic\nscattering in the chiral metal, focussing particularly on fluctuations of\nconductance, $\\delta g(B)$, with magnetic field, $B$. The correlation function\n$<\\delta g(B) \\delta g(B+\\delta B)>$ provides information on the inelastic\nscattering rate, $\\tau_{in}^{-1}$, through both the variance of fluctuations\nand the range of correlations in $\\delta B$. We calculate this correlation\nfunction for samples which are not fully phase coherent. Two regimes of\nbehaviour exist, according to whether $\\tau_{in}^{-1}$ is smaller or larger\nthan $\\tau_{\\perp}^{-1}$, the rate for inter-edge tunneling, and we give\nresults in both regimes. We also investigate dynamical screening of Coulomb\ninteractions in the chiral metal and calculate the contribution to\n$\\tau_{in}^{-1}$ from electron-electron scattering, finding $\\tau_{in}^{-1}\n\\propto T^{3/2}$ for $\\tau_{in}^{-1} \\ll \\tau_{\\perp}^{-1}$ at temperature $T$."
    },
    {
        "anchor": "CoFeB/MgO/CoFeB structures with orthogonal easy axes: perpendicular\n  anisotropy and damping: We report on the Gilbert damping parameter $\\alpha$, the effective\nmagnetization $4\\pi M_{eff}$, and the asymmetry of the $g$-factor in\nbottom-CoFeB(0.93~nm)/MgO(0.90--1.25~nm)/CoFeB(1.31~nm)-top as-deposited\nsystems.\n  Magnetization of CoFeB layers exhibits a specific noncollinear configuration\nwith orthogonal easy axes and with $4\\pi M_{eff}$ values of $+2.2$ kG and\n$-2.3$ kG for the bottom and top layers, respectively. We show that $4\\pi\nM_{eff}$ depends on the asymmetry $g_\\perp - g_\\parallel$ of the $g$-factor\nmeasured in the perpendicular and the in-plane directions revealing a highly\nnonlinear relationship. In contrast, the Gilbert damping is practically the\nsame for both layers. Annealing of the films results in collinear easy axes\nperpendicular to the plane for both layers. However, the linewidth is strongly\nincreased due to enhanced inhomogeneous broadening.",
        "positive": "Photon correlation studies of single GaN quantum dots: We present measurements of the second-order coherence function on emission\nfrom single GaN quantum dots. In some cases a large degree of photon\nantibunching is observed, demonstrating isolation of a single quantum system.\nFor a selected quantum dot, we study the dependence of photon antibunching on\nexcitation power and temperature. Using pulsed excitation, we demonstrate an\nultraviolet triggered single-photon source operating at a wavelength of 358 nm."
    },
    {
        "anchor": "Large yield production of high mobility freely suspended graphene\n  electronic devices on a PMGI based organic polymer: The recent observation of fractional quantum Hall effect in high mobility\nsuspended graphene devices introduced a new direction in graphene physics, the\nfield of electron-electron interaction dynamics. However, the technique used\ncurrently for the fabrication of such high mobility devices has several\ndrawbacks. The most important is that the contact materials available for\nelectronic devices are limited to only a few metals (Au, Pd, Pt, Cr and Nb)\nsince only those are not attacked by the reactive acid (BHF) etching\nfabrication step. Here we show a new technique which leads to mechanically\nstable suspended high mobility graphene devices which is compatible with almost\nany type of contact material. The graphene devices prepared on a\npolydimethylglutarimide based organic resist show mobilities as high as 600.000\ncm^2/Vs at an electron carrier density n = 5.0 10^9 cm^-2 at 77K. This\ntechnique paves the way towards complex suspended graphene based spintronic,\nsuperconducting and other types of devices.",
        "positive": "Floquet states in (LaNiO$_3$)$_2$/(LaAlO$_3$)$_N$ heterostructures grown\n  along the (111) direction: Using Floquet-Bloch theory we study the effect of circularly and linearly\npolarized light on the electronic structure of (LaNiO$_3$)$_2$/(LaAlO$_3$)$_N$\nheterostructure grown along the (111) direction. In equilibrium, a\ntight-binding fit to the first principles band structure shows that\nnearest-neighbor hopping plays a dominant role while second-neighbor hopping\nbreaks the particle-hole symmetry and determines the finer band features. The\nfour bands of the LaNiO$_3$ bilayer exhibit both quadratic band touching points\nand Dirac points. By varying the amplitude of the incident light, one can\nindependently tune the first and second-neighbor hopping for fixed frequency,\nwhich leads to considerable control over the Floquet band structure. We\ninvestigate this control in detail, and study how the quadratic and Dirac band\ntouchings are influenced by the polarization and intensity of the light. We\nderive effective 2-band Hamiltonians (for both quadratic and Dirac band\ntouching points) that accurately captures these results. We further study an\nextended model which explicitly includes oxygen $p$-orbitals and compare the\nresults to the effective model that contains only the nickel $d$-orbitals. We\nconclude with a computation of the frequency dependent optical Hall\nconductivity using the full four band model and analyze the various inter-band\ncontributions of the Floquet modes."
    },
    {
        "anchor": "The effect of dynamical Bloch oscillations on optical-field-induced\n  current in a wide gap dielectric: We consider the motion of charge carriers in a bulk wide-gap dielectric\ninteracting with a few-cycle laser pulse. A semiclassical model based on Bloch\nequations is applied to describe the emerging time-dependent macroscopic\ncurrents for laser intensities approaching the damage threshold. At such laser\nintensities, electrons can reach edges of the first Brillouin zone even for\nelectron-phonon scattering rates as high as those known for SiO_2. We find\nthat, whenever this happens, Brag-like reflections of electron waves, also\nknown as Bloch oscillations, affect the dependence of the charge displaced by\nthe laser pulse on its carrier-envelope phase.",
        "positive": "Nonlocal Scattering Matrix Description of Anisotropic Polar\n  Heterostructures: Polar dielectrics are a promising platform for mid-infrared nanophotonics,\nallowing for nanoscale electromagnetic energy confinement in oscillations of\nthe crystal lattice. We recently demonstrated that in nanoscopic polar systems\na local description of the optical response fails, leading to erroneous\npredictions of modal frequencies and electromagnetic field enhancements. In\nthis Paper we extend our previous work providing a scattering matrix theory of\nthe nonlocal optical response of planar, anisotropic, layered polar dielectric\nheterostructures. The formalism we employ allows for the calculation of both\nreflection and transmission coefficients, and of the guided mode spectrum. We\napply our theory to complex AlN/GaN superlattices, demonstrating the strong\nnonlocal tuneability of the optical response arising from hybridisation between\nphoton and phonon modes. The numerical code underlying these calculations is\nprovided in an online repository to serve as a tool for the design of\nphonon-based mid-infrared optoelectronic devices."
    },
    {
        "anchor": "Nonlinear magnetoconductance of a classical ballistic system: We study nonlinear transport through a classical ballistic system accounting\nfor the Coulomb interaction between electrons. The joint effect of the applied\nbias $V$ and magnetic field $H$ on the electron trajectories results in a\ncomponent of the non-linear current $I(V,H)$ which lacks the $H\\to -H$\nsymmetry: $\\delta I=\\alpha_{cl} V^2 H$. At zero temperature the magnitude of\n$\\alpha_{cl}$ is of the same order as that arising from the quantum\ninterference mechanism. At higher temperatures the classical mechanism is\nexpected to dominate due to its relatively weak temperature dependence.",
        "positive": "Magnetic Droplet Solitons: Magnetic droplet solitons are dynamical magnetic textures that form due to an\nattractive interaction between spin waves in thin films with perpendicular\nmagnetic anisotropy. Spin currents and the spin torques associated with these\ncurrents enable their formation as they provide a means to excite\nnon-equilibrium spin wave populations and compensate their decay. Recent years\nhave seen rapid advances in experiments that realize and study magnetic\ndroplets. Important advances include the first direct x-ray images of droplets,\ndetermination of their threshold and sustaining currents, measurement of their\ngeneration and annihilation time and evidence for drift instabilities, which\ncan limit their lifetime in spin-transfer nanocontacts. This article reviews\nthese studies and contrasts these solitons to other types of spin-current\nexcitations such as spin-wave bullets, and static magnetic textures, including\nmagnetic vortices and skyrmions. Magnetic droplet solitons can also serve as\ncurrent controlled microwave frequency oscillators with potential applications\nin neuromorphic chips as nonlinear oscillators with memory."
    },
    {
        "anchor": "Size Dependence of the Multiple Exciton Generation Rate in CdSe Quantum\n  Dots: The multiplication rates of hot carriers in CdSe quantum dots are quantified\nusing an atomistic pseudopotential approach and first order perturbation\ntheory. Both excited holes and electrons are considered, and electron-hole\nCoulomb interactions are accounted for. We find that holes have much higher\nmultiplication rates than electrons with the same excess energy due to the\nlarger density of final states (positive trions). When electron-hole pairs are\ngenerated by photon absorption, however, the net carrier multiplication rate is\ndominated by photogenerated electrons, because they have on average much higher\nexcess energy. We also find, contrary to earlier studies, that the effective\nCoulomb coupling governing carrier multiplication is energy dependent. We show\nthat smaller dots result in a decrease in the carrier multiplication rate for a\ngiven absolute photon energy. However, if the photon energy is scaled by the\nvolume dependent optical gap, then smaller dots exhibit an enhancement in\ncarrier multiplication for a given relative energy.",
        "positive": "Interplay between Topological States and Rashba States as Manifested on\n  Surface Steps at Room Temperature: The unique spin texture of quantum states in topological materials underpins\nmany proposed spintronic applications. However, realizations of such great\npotential are stymied by perturbations, such as temperature and local fields\nimposed by impurities and defects, that can render a promising quantum state\nuncontrollable. Here, we report room-temperature observation of interaction\nbetween Rashba states and topological surface states, which manifests unique\nspin textures controllable by layer thickness of thin films. Specifically, we\ncombine scanning tunneling microscopy/spectroscopy with the first-principles\ntheoretical calculation to find the robust Rashba states coexisting with\ntopological surface states along the surface steps with characteristic spin\ntextures in momentum space. The Rashba edge states can be switched off by\nreducing the thickness of a topological insulator Bi2Se3 to bolster their\ninteraction with the hybridized topological surface states. The study unveils a\nmanipulating mechanism of the spin textures at room temperature, reinforcing\nthe necessity of thin film technology in controlling quantum states."
    },
    {
        "anchor": "The quench dynamics of a dissipative quantum system: a renormalization\n  group study: We study dissipation in a small quantum system coupled to an environment held\nin thermodynamic equilibrium. The relaxation dynamics of a system subject to an\nabrupt quench in the parameters of the underlying Hamiltonian is investigated\nusing two complementary renormalization group approaches. The methods are\napplied to the Ohmic spin-boson model close to the coherent-to-incoherent\ntransition. In particular, the role of non-Markovian memory for the relaxation\nbefore and after the quench of the spin-boson coupling and the Zeeman splitting\nof the up and down spin is investigated.",
        "positive": "2D compressibility of surface states on 3D topological insulators: We develop a theory for the compressibility of the surface states of 3D\ntopological insulators and propose that surface probes of the compressibility\nvia scanning single electron transistor microscopy will be a straightforward\nway to access the topological states without interference from the bulk states.\nWe describe the single-particle nature of the surface states taking into\naccount an accurate Hamiltonian for the bands and then include the contribution\nfrom electron--electron interactions and discuss the implications of the\nultra-violet cutoff, including the universality of the exchange contribution\nwhen expressed in dimensionless units. We also compare the theory with\nexperimentally obtained d{\\mu}/dn as extracted from angle-resolved\nphotoemission spectroscopy measurements. Finally, we point out that\ninteraction-driven renormalization of the Fermi velocity may be discernible via\nthis technique."
    },
    {
        "anchor": "Non-diffracting states in one-dimensional Floquet photonic topological\n  insulators: One dimensional laser-written modulated photonic lattices are known to be\nparticularly suitable for diffraction management purposes. Here, we address the\nconnection between discrete non-diffracting states and topological properties\nin such devices through the experimental observation and identification of\nthree classes of non-diffracting state. The first one corresponds to\ntopologically protected edge states, recently predicted in Floquet topological\ninsulators, while the second and third are both bulk modes. One of them\ntestifies of a topological transition, although presenting topological features\ndifferent from those of the edge states, whether the other one result from\nspecific band structure engineering.",
        "positive": "Comments on \"Anomalous-Filling-Factor-Dependent Nuclear Spin\n  Polarization in a 2D Electron System: Quantum Hall Effect\" by J.H.Smet, K.\n  von Klitzing et al, Phys. Rev. Lett. 92, 086802(2004): We find that the nuclear-spin polarization has not been treated correctly.\nThe references given are those of wrong papers. The credits assigned for\ndiscoveries are also not correct. Incorrect theories have been cited. The\nreference to the correct theory has been neglected. Because there are lots of\ngood people, so they do not want to give reference to my papers even though\nthey have not solved the problem of quantum Hall effect and we have."
    },
    {
        "anchor": "Quantized Ballistic Transport of Electrons and Electron Pairs in\n  LaAlO$_3$/SrTiO$_3$ Nanowires: SrTiO$_3$-based heterointerfaces support quasi-two-dimensional (2D) electron\nsystems that are analogous to III-V semiconductor heterostructures, but also\npossess superconducting, magnetic, spintronic, ferroelectric, and ferroelastic\ndegrees of freedom. Despite these rich properties, the relatively low\nmobilities of 2D complex-oxide interfaces appear to preclude ballistic\ntransport in 1D. Here we show that the 2D LaAlO$_3$/SrTiO$_3$ interface can\nsupport quantized ballistic transport of electrons and (non-superconducting)\nelectron pairs within quasi-1D structures that are created using a\nwell-established conductive atomic-force microscope (c-AFM) lithography\ntechnique. The nature of transport ranges from truly single-mode (1D) to\nthree-dimensional (3D), depending on the applied magnetic field and gate\nvoltage. Quantization of the lowest $e^2/h$ plateau indicate a ballistic\nmean-free path $l_{MF}\\sim$ 20 $\\mu$m, more than two orders of magnitude larger\nthan for 2D LaAlO$_3$/SrTiO$_3$ heterostructures. Non-superconducting electron\npairs are found to be stable in magnetic fields as high as $B=11$ T, and\npropagate ballistically with conductance quantized at 2$e^2/h$. Theories of\none-dimensional (1D) transport of interacting electron systems depend crucially\non the sign of the electron-electron interaction, which may help explain the\nhighly ballistic transport behavior. The 1D geometry yields new insights into\nthe electronic structure of the LaAlO$_3$/SrTiO$_3$ system and offers a new\nplatform for the study of strongly interacting 1D electronic systems.",
        "positive": "Asymmetric $d$-wave superconducting topological insulator in proximity\n  with a magnetic order: In the framework of the Dirac-Bogoliubov-de Gennes formalism, we investigate\nthe transport properties in the surface of a 3-dimensional topological\ninsulator-based hybrid structure, where the ferromagnetic and superconducting\norders are simultaneously induced to the surface states via the proximity\neffect. The superconductor gap is taken to be spin-singlet $d$-wave symmetry.\nThe asymmetric role of this gap respect to the electron-hole exchange, in one\nhand, affects the topological insulator superconducting binding excitations\nand, on the other hand, gives rise to forming distinct Majorana bound states at\nthe ferromagnet/superconductor interface. We propose a topological insulator\nN/F/FS junction and proceed to clarify the role of $d$-wave asymmetry pairing\nin the resulting subgap and overgap tunneling conductance. The perpendicular\ncomponent of magnetizations in F and FS regions can be at the parallel and\nantiparallel configurations leading to capture the experimentally important\nmagnetoresistance (MR) of junction. It is found that the zero-bias conductance\nis strongly sensitive to the magnitude of magnetization in FS region $m_{zfs}$\nand orbital rotated angle $\\alpha$ of superconductor gap. The negative MR only\noccurs in zero orbital rotated angle. This result can pave the way to\ndistinguish the unconventional superconducting state in the relating\ntopological insulator hybrid structures."
    },
    {
        "anchor": "Ambipolar Transport in Narrow Bandgap Semiconductor InSb Nanowires: We report on transport measurement study of top-gated field effect\ntransistors made out of InSb nanowires grown by chemical vapor deposition. The\ntransistors exhibit ambipolar transport characteristics revealed by three\ndistinguished gate-voltage regions: In the middle region where the fermi level\nresides within the bandgap, the electrical resistance shows an exponential\ndependence on temperature and gate voltage. With either more positive or\nnegative gate voltages, the devices enter the electron and hole transport\nregimes, revealed by a resistance decreasing linearly with decreasing\ntemperature. From the transport measurement data of a 1-$\\mu$m-long device made\nfrom a nanowire of 50 nm in diameter, we extract a bandgap energy of 190-220\nmeV. The off-state current of this device is found to be suppressed within the\nmeasurement noise at a temperature of T = 4 K. A shorter, 260-nm-long device is\nfound to exhibit a finite off-state current and a hole, on-state,\ncircumference-normalized current of 11 $\\mu$A/$\\mu$m at V$_D$ = 50 mV which is\nthe highest for such a device to our knowledge. The ambipolar transport\ncharacteristics make the InSb nanowires attractive for CMOS electronics, hybrid\nelectron-hole quantum systems and hole based spin qubits.",
        "positive": "Modeling ballistic effects in frequency-dependent transient thermal\n  transport using diffusion equations: Understanding ballistic phonon transport effects in transient\nthermoreflectance experiments and explaining the observed deviations from\nclassical theory remains a challenge. Diffusion equations are simple and\ncomputationally efficient but are widely believed to break down when the\ncharacteristic length scale is similar or less than the phonon mean-free-path.\nBuilding on our prior work, we demonstrate how well-known diffusion equations,\nnamely the hyperbolic heat equation and the Cattaneo equation, can be used to\nmodel ballistic phonon effects in frequency-dependent periodic steady-state\nthermal transport. Our analytical solutions are found to compare excellently to\nrigorous numerical results of the phonon Boltzmann transport equation. The\ncorrect physical boundary conditions can be different from those traditionally\nused and are paramount for accurately capturing ballistic effects. To\nillustrate the technique, we consider a simple model problem using two\ndifferent, commonly-used heating conditions. We demonstrate how this framework\ncan easily handle detailed material properties, by considering the case of bulk\nsilicon using a full phonon dispersion and mean-free-path distribution. This\nphysically transparent approach provides clear insights into the nonequilibrium\nphysics of quasi-ballistic phonon transport and its impact on thermal transport\nproperties."
    },
    {
        "anchor": "Scattering of electron from a disk in 2D electron gas: full cross\n  section, transport cross section, and the interaction correction: It is known that the presence of the Fermi sea modifies the scattering of an\nelectron from a point-like impurity. This is due to the Friedel oscillations of\nthe electron density around the impurity. These oscillations create an\nadditional scattering potential for incident electrons. The closer the energy\nof the incident electron to the Fermi level, the stronger the additional\nscattering. We study this effect for the case when the impurity is not\npoint-like but rather a hard disk, with a radius much bigger than the de\nBroglie wavelength. We start with a careful examination of the full and\ntransport cross sections from an extended target. Both cross sections approach\ntheir limiting values upon increasing the wave vector of the incident electron.\nWe establish that the transport cross section saturates much faster than the\nfull cross section. With regard to the interaction correction, we establish\nthat it vanishes for the full cross section, while for the transport cross\nsection, it is enhanced compared to the case of a point-like scatterer.",
        "positive": "Highly efficient spin-orbit torque and switching of layered ferromagnet\n  Fe3GeTe2: Among van der Waals (vdW) layered ferromagnets, Fe3GeTe2 (FGT) is an\nexcellent candidate material to form FGT/heavy metal heterostructures for\nstudying the effect of spin-orbit torques (SOT). Its metallicity, strong\nperpendicular magnetic anisotropy built in the single atomic layers, relatively\nhigh Curie temperature (Tc about 225 K) and electrostatic gate tunability offer\na tantalizing possibility of achieving the ultimate high SOT limit in monolayer\nall-vdW nanodevices. The spin current generated in Pt exerts a damping-like SOT\non FGT magnetization. At about 2.5x1011 A/m2 current density,SOT causes the FGT\nmagnetization to switch, which is detected by the anomalous Hall effect of FGT.\nTo quantify the SOT effect, we measure the second harmonic Hall responses as\nthe applied magnetic field rotates the FGT magnetization in the plane. Our\nanalysis shows that the SOT efficiency is comparable with that of the best\nheterostructures containing three-dimensional (3D) ferromagnetic metals and\nmuch larger than that of heterostructures containing 3D ferrimagnetic\ninsulators. Such large efficiency is attributed to the atomically flat FGT/Pt\ninterface, which demonstrates the great potential of exploiting vdW\nheterostructures for highly efficient spintronic nanodevices."
    },
    {
        "anchor": "Microwave photoconductivity of a 2D electron gas: Mechanisms and their\n  interplay at high radiation power: We develop a systematic theory of microwave-induced oscillations in the\nmagnetoresistivity of a two-dimensional electron gas, focusing on the regime of\nstrongly overlapping Landau levels. At linear order in microwave power, two\nnovel mechanisms of the oscillations (``quadrupole'' and ``photovoltaic'') are\nidentified, in addition to those studied before (``displacement'' and\n``inelastic''). The quadrupole and photovoltaic mechanisms are shown to be the\nonly ones that give rise to oscillations in the nondiagonal part of the\nphotoconductivity tensor. In the diagonal part, the inelastic contribution\ndominates at moderate microwave power, while at elevated power the other\nmechanisms become relevant. We demonstrate the crucial role of feedback\neffects, which lead to a strong interplay of the four mechanisms in the\nnonlinear photoresponse and yield, in particular, a nonmonotonic power\ndependence of the photoconductivity, narrowing of the magnetoresonances, and a\nnontrivial structure of the Hall photoresponse. At ultrahigh power, all effects\nrelated to the Landau quantization decay due to a combination of the feedback\nand multiphoton effects, restoring the classical Drude conductivity.",
        "positive": "Large spin-wave bullet in a ferrimagnetic insulator driven by spin Hall\n  effect: Due to its transverse nature, spin Hall effects (SHE) provide the possibility\nto excite and detect spin currents and magnetization dynamics even in magnetic\ninsulators. Magnetic insulators are outstanding materials for the investigation\nof nonlinear phenomena and for novel low power spintronics applications because\nof their extremely low Gilbert damping. Here, we report on the direct imaging\nof electrically driven spin-torque ferromagnetic resonance (ST-FMR) in the\nferrimagnetic insulator Y$_3$Fe$_5$O$_{12}$ based on the excitation and\ndetection by SHEs. The driven spin dynamics in Y$_3$Fe$_5$O$_{12}$ is directly\nimaged by spatially-resolved microfocused Brillouin light scattering (BLS)\nspectroscopy. Previously, ST-FMR experiments assumed a uniform precession\nacross the sample, which is not valid in our measurements. A strong spin-wave\nlocalization in the center of the sample is observed indicating the formation\nof a nonlinear, self-localized spin-wave `bullet'."
    },
    {
        "anchor": "Nanoscale variation of the Rashba energy in BiTeI: BiTeI is a polar semiconductor with strong spin-orbit coupling (SOC) that\nproduces large Rashba spin splitting. Due to its potential utility in\nspintronics and magnetoelectrics, it is essential to understand how defects\nimpact the spin transport in this material. Using scanning tunneling microscopy\nand spectroscopy, we image ring-like charging states of single-atom defects on\nthe iodine surface of BiTeI. We observe nanoscale variations in the Rashba\nenergy around each defect, which we correlate with the local electric field\nextracted from the bias dependence of each ring radius. Our data demonstrate\nthe local impact of atomic defects on the Rashba effect, which is both a\nchallenge and an opportunity for the development of future nanoscale spintronic\ndevices.",
        "positive": "Epitaxial growth and Photoluminescence Excitation spectroscopy of CdSe\n  Quantum Dots in (Zn,Cd)Se barrier: Design, epitaxial growth, and resonant spectroscopy of CdSe Quantum Dots\n(QDs) embedded in an innovative (Zn,Cd)Se barrier are presented. The (Zn,Cd)Se\nbarrier enables shifting of QDs energy emission down to 1.87 eV, that is below\nthe energy of Mn$^{2+}$ ions internal transition (2.1 eV). This opens a\nperspective for implementation of epitaxial CdSe QDs doped with several Mn ions\nas, e. g., the light sources in high quantum yield magnetooptical devices.\nPolarization resolved Photoluminescence Excitation measurements of individual\nQDs reveal sharp ($\\Gamma <$ 150 $\\mu$eV) maxima and transfer of optical\npolarization to QD confining charged exciton state with efficiency attaining 26\n%. The QD doping with single Mn$^{2+}$ ions is achieved."
    },
    {
        "anchor": "Topological surface states in thick partially relaxed HgTe film: Surface states of topological insulators (TIs) have been playing the central\nrole in the majority of outstanding investigations in low-dimensional electron\nsystems for more than 10 years. TIs based on high-quality strained HgTe films\ndemonstrate a variety of subtle physical effects. The strain leads to a bulk\nband gap but limits a maximum HgTe strained film thickness, and therefore, the\nmajority of experiments were performed on films with a thickness of less than\n100 nm. Since a spatial separation of topological states is crucial for the\nstudy of a single-surface response, it is essential to increase the HgTe\nthickness further. In this work, by combining transport measurements together\nwith capacitance spectroscopy, we perform an analysis of a 200-nm partially\nrelaxed HgTe film. The Drude fit of the classical magnetotransport reveals the\nambipolar electron-hole transport with a high electron mobility. A detailed\nanalysis of Shubnikov-de Haas oscillations in both conductivity and capacitance\nallows us to distinguish three groups of electrons, identified as electrons on\ntop and bottom surfaces and bulk electrons. The indirect bulk energy gap value\nis found to be close to zero. It is established that the significant gap\ndecrease does not affect the surface states, which are found to be well\nresolved and spin nondegenerate. The presented techniques allow investigations\nof other three-dimensional TIs, regardless of the presence of bulk\nconductivity.",
        "positive": "Many-body effective thermal conductivity in phase-change nanoparticle\n  chains due to near-field radiative heat transfer: In dense systems composed of numerous nanoparticles, direct simulations of\nnear-field radiative heat transfer (NFRHT) require considerable computational\nresources. NFRHT for the simple one-dimensional nanoparticle chains embedded in\na non-absorbing host medium is investigated from the point of view of the\ncontinuum by means of an approach combining the many-body radiative heat\ntransfer theory and the Fourier law. Effects of the phase change of the\ninsulator-metal transition material (VO$_2$), the complex many-body interaction\n(MBI) and the host medium relative permittivity on the characteristic effective\nthermal conductivity (ETC) are analyzed. The ETC for VO$_2$ nanoparticle chains\nbelow the transition temperature can be as high as 50 times of that above the\ntransition temperature due to the phase change effect. The strong coupling in\nthe insulator-phase VO$_2$ nanoparticle chain accounts for its high ETC as\ncompared to the low ETC for the chain at the metallic phase, where there is a\nmismatch between the characteristic thermal frequency and resonance frequency.\nThe strong MBI is in favor of the ETC. For SiC nanoparticle chains, the MBI\neven can double the ETC as compared to those without considering the MBI\neffect. For the dense chains, a strong MBI enhances the ETC due to the strong\ninter-particles couplings. When the chains go more and more dilute, the MBI can\nbe neglected safely due to negligible couplings. The host medium relative\npermittivity significantly affects the inter-particles couplings, which\naccounts for the permittivity-dependent ETC for the VO$_2$ nanoparticle chains."
    },
    {
        "anchor": "Information constraint in open quantum systems: We propose an effect called information constraint which is characterized by\nthe existence of different decay rates of signal strengths propagating along\nopposite directions. It is an intrinsic property of a type of open quantum\nsystem, which does not rely on boundary conditions. We define the value of\ninformation constraint ($I_C$) as the ratio of different decay rates and derive\nthe analytical representation of $I_C$ for general quadratic Lindbladian\nsystems. Based on information constraint, we can provide a simple and elegant\nexplanation of chiral and helical damping, and get the local maximum points of\nrelative particle number for the periodical boundary system, consistent with\nnumerical calculations. Inspired by information constraint, we propose and\nprove the correspondence between edge modes and damping modes. A new damping\nmode called Dirac damping is constructed, and chiral/helical damping can be\nregarded as a special case of Dirac damping.",
        "positive": "Phenomenological formula for Quantum Hall resistivity based on the\n  Riemann zeta function: We propose a formula constructed out of elementary functions that captures\nmany of the detailed features of the transverse resistivity $\\rho_{xy}$ for the\ninteger quantum Hall effect. It is merely a phenomenological formula in the\nsense that it is not based on any transport calculation for a specific class of\nphysical models involving electrons in a disordered landscape, thus, whether a\nphysical model exists which realizes this resistivity remains an open question.\nNevertheless, since the formula involves the Riemann zeta function and its\nnon-trivial zeros play a central role, it is amusing to consider the\nimplications of the Riemann Hypothesis in light of it."
    },
    {
        "anchor": "Measuring current by counting electrons in a nanowire quantum dot: We measure current by counting single electrons tunneling through an InAs\nnanowire quantum dot. The charge detector is realized by fabricating a quantum\npoint contact in close vicinity to the nanowire. The results based on electron\ncounting compare well to a direct measurements of the quantum dot current, when\ntaking the finite bandwidth of the detector into account. The ability to detect\nsingle electrons also opens up possibilities for manipulating and detecting\nindividual spins in nanowire quantum dots.",
        "positive": "Coulomb screening in graphene with topological defects: We analyze the screening of an external Coulomb charge in gapless graphene\ncone, which is taken as a prototype of a topological defect. In the subcritical\nregime, the induced charge is calculated using both the Green's function and\nthe Friedel sum rule. The dependence of the polarization charge on the Coulomb\nstrength obtained from the Green's function clearly shows the effect of the\nconical defect and indicates that the critical charge itself depends on the\nsample topology. Similar analysis using the Friedel sum rule indicates that the\ntwo results agree for low values of the Coulomb charge but differ for the\nhigher strengths, especially in the presence of the conical defect. For a given\nsubcritical charge, the transport cross-section has a higher value in the\npresence of the conical defect. In the supercritical regime we show that the\ncoefficient of the power law tail of polarization charge density can be\nexpressed as a summation of functions which vary log periodically with the\ndistance from the Coulomb impurity. The period of variation depends on the\nconical defect. In the presence of the conical defect, the Fano resonances\nbegin to appear in the transport cross-section for a lower value of the Coulomb\ncharge. For both sub and supercritical regime we derive the dependence of LDOS\non the conical defect. The effects of generalized boundary condition on the\nphysical observables are also discussed."
    },
    {
        "anchor": "Optimal work-to-work conversion of a nonlinear quantum brownian duet: Performances of work-to-work conversion are studied for a dissipative\nnonlinear quantum system with two isochromatic phase-shifted drives. It is\nshown that for weak Ohmic damping simultaneous maximization of efficiency with\nfinite power yield and low power fluctuations can be achieved. Optimal\nperformances of these three quantities are accompanied by a shortfall of the\ntrade-off bound recently introduced for classical thermal machines. This bound\ncan be undercut down to zero for sufficiently low temperature and weak\ndissipation, where the non-Markovian quantum nature dominates. Analytic results\nare given for linear thermodynamics. These general features can persist in the\nnonlinear driving regime near to a maximum of the power yield and a minimum of\nthe power fluctuations. This broadens the scope to a new operation field beyond\nlinear response.",
        "positive": "Microscopic theory of phonon-induced effects on semiconductor quantum\n  dot decay dynamics in cavity QED: We investigate the influence of the electron-phonon interaction on the decay\ndynamics of a quantum dot coupled to an optical microcavity. We show that the\nelectron-phonon interaction has important consequences on the dynamics,\nespecially when the quantum dot and cavity are tuned out of resonance, in which\ncase the phonons may add or remove energy leading to an effective non-resonant\ncoupling between quantum dot and cavity. The system is investigated using two\ndifferent theoretical approaches: (i) a second-order expansion in the bare\nphonon coupling constant, and (ii) an expansion in a polaron-photon coupling\nconstant, arising from the polaron transformation which allows an accurate\ndescription at high temperatures. In the low temperature regime we find\nexcellent agreement between the two approaches. An extensive study of the\nquantum dot decay dynamics is performed, where important parameter dependencies\nare covered. We find that in general the electron-phonon interaction gives rise\nto a greatly increased bandwidth of the coupling between quantum dot and\ncavity. At low temperature an asymmetry in the quantum dot decay rate is\nobserved, leading to a faster decay when the quantum dot has a larger energy\nthan to the cavity. We explain this as due to the absence of phonon absorption\nprocesses. Furthermore, we derive approximate analytical expressions for the\nquantum dot decay rate, applicable when the cavity can be adiabatically\neliminated. The expressions lead to a clear interpretation of the physics and\nemphasizes the important role played by the effective phonon density,\ndescribing the availability of phonons for scattering, in quantum dot decay\ndynamics. Based on the analytical expressions we present the parameter regimes\nwhere phonon effects are expected to be important. Also, we include all\ntechnical developments in appendices."
    },
    {
        "anchor": "Strength of the dominant scatterer in graphene on silicon oxide: A large variability of carrier mobility of graphene-based field effect\ntransistors hampers graphene science and technology. We determine the\nscattering strength of the dominant scatterer responsible for the variability\nof graphene-based transistors on silicon oxide. The strength of the scatterer\nis found to be more consistent with charged impurities than with resonant\nimpurities.",
        "positive": "Coulomb Drag Between Parallel Ballistic Quantum Wires: The Coulomb drag between parallel, {\\it ballistic} quantum wires is studied\ntheoretically in the presence of a perpendicular magnetic field B. The\ntransresistance R_D shows peaks as a function of the Fermi level and splitting\nenergy between the 1D subbands of the wires. The sharpest peaks appear when the\nFermi level crosses the subband extrema so that the Fermi momenta are small.\nTwo other kinds of peaks appear when either {\\it intra}- or {\\it inter}-subband\ntransitions of electrons have maximum probability; the {\\it intra}-subband\ntransitions correspond to a small splitting energy. R_D depends on the field B\nin a nonmonotonic fashion: it decreases with B, as a result of the suppression\nof backscattering, and increases sharply when the Fermi level approaches the\nsubband bottoms and the suppression is outbalanced by the increase of the\nCoulomb matrix elements and of the density of states."
    },
    {
        "anchor": "Magnetic Dirac Semimetals in Three Dimensions: We present a new type of three-dimensional essential Dirac semimetal with\nmagnetic ordering. The Dirac points are protected by the magnetic space groups\nand cannot be gapped without lowering such symmetries, where the combined\nantiunitary symmetry of half-translation operator and time-reversal plays an\nessential role. We introduce two explicit tight-binding models for space groups\n$16$ and $102$, which possesses Dirac point at time-reversal-invariant momenta\nof surface Brillouin zone. In contrast to the time-reversal-invariant essential\nDirac semimetal, the magnetic space groups here can be either symmorphic or\nnon-symmorphic, and the magnetic DSM is symmetry tuned to the boundary between\nweak topologically distinct insulating phases. Interestingly, the\nsymmetry-breaking perturbations could lead to an ideal Weyl semimetal phase\nwith only two minimal Weyl points pinned exactly at the Fermi energy for\nfilling $\\nu\\in4\\mathbb{Z}+2$. By reducing the dimensionality we are able to\naccess the Dirac and Weyl semimetal phases in two dimensions.",
        "positive": "Effect of stretching on the ballistic conductance of Au nanocontacts in\n  presence of CO: a density functional study: CO adsorption on an Au monatomic chain is studied within density functional\ntheory in nanocontact geometries as a function of the contact stretching. We\ncompare the bridge and atop adsorption sites of CO, finding that the bridge\nsite is energetically favored at all strains studied here. Atop adsorption\ngives rise to an almost complete suppression of the ballistic conductance of\nthe nanocontact, while adsorption at the bridge site results in a conductance\nvalue close to 0.6 G0, in agreement with previous experimental data. We show\nthat only the bridge site can qualitatively account for the evolution of the\nconductance as a function of the contact stretching observed in the\nexperimental conductance traces. The numerical discrepancy between the\ntheoretical and experimental conductance slopes is rationalized through a\nsimple model for the elastic response of the metallic leads. We also verify\nthat our conductance values are not affected by the specific choice of the\nnanocontact geometry by comparing two different atomistic models for the tips."
    },
    {
        "anchor": "Topological Photonic Quasicrystals: Fractal Topological Spectrum and\n  Protected Transport: We show that it is possible to have a topological phase in two-dimensional\nquasicrystals without any magnetic field applied, but instead introducing an\nartificial gauge field via dynamic modulation. This topological quasicrystal\nexhibits scatter-free unidirectional edge states that are extended along the\nsystem's perimeter, contrary to the states of an ordinary quasicrystal system,\nwhich are characterized by power-law decay. We find that the spectrum of this\nFloquet topological quasicrystal exhibits a rich fractal (self-similar)\nstructure of topological \"minigaps,\" manifesting an entirely new phenomenon:\nfractal topological systems. These topological minigaps form only when the\nsystem size is sufficiently large because their gapless edge states penetrate\ndeep into the bulk. Hence, the topological structure emerges as a function of\nthe system size, contrary to periodic systems where the topological phase can\nbe completely characterized by the unit cell. We demonstrate the existence of\nthis topological phase both by using a topological index (Bott index) and by\nstudying the unidirectional transport of the gapless edge states and its\nrobustness in the presence of defects. Our specific model is a Penrose lattice\nof helical optical waveguides - a photonic Floquet quasicrystal; however, we\nexpect this new topological quasicrystal phase to be universal.",
        "positive": "Equivalence of Topological Insulators and Superconductors: Systems of free fermions are classified by symmetry, space dimensionality,\nand topological properties described by K-homology. Those systems belonging to\ndifferent classes are inequivalent. In contrast, we show that by taking a\nmany-body/Fock space viewpoint it becomes possible to establish equivalences of\ntopological insulators and superconductors in terms of duality transformations.\nThese mappings connect topologically inequivalent systems of fermions, jumping\nacross entries in existent classification tables, because of the phenomenon of\nsymmetry transmutation by which a symmetry and its dual partner have identical\nalgebraic properties but very different physical interpretations. To constrain\nour study to established classification tables, we define and characterize\nmathematically Gaussian dualities as dualities mapping free fermions to free\nfermions (and interacting to interacting). By introducing a large, flexible\nclass of Gaussian dualities we show that any insulator is dual to a\nsuperconductor, and that fermionic edge modes are dual to Majorana edge modes,\nthat is, the Gaussian dualities of this paper preserve the bulk-boundary\ncorrespondence. Transmutation of relevant symmetries, particle number,\ntranslation, and time reversal is also investigated in detail. As illustrative\nexamples, we show the duality equivalence of the dimerized Peierls chain and\nthe Majorana chain of Kitaev, and a two-dimensional Kekul\\'e-type topological\ninsulator, including graphene as a special instance in coupling space, dual to\na p-wave superconductor. Since our analysis extends to interacting fermion\nsystems we also briefly discuss some such applications."
    },
    {
        "anchor": "Critical phenomena of nano phase evolution in a first order transition: First order phase transitions occur discretely from one state to another,\nhowever they often display continuous behavior. To understand this nature, it\nis essential to probe how the emergent phase nucleates, interacts and evolves\nwith the initial phase across the transition at microscopic scales. Here, the\nprototypical first-order magneto-structural transition in FeRh is used to\ninvestigate these phenomena. We find that the temperature evolution of the\nfinal phase exhibits critical behavior. Furthermore, a difference between the\nstructure and magnetic transition temperatures reveals a novel intermediate\nphase created from the interface between the initial and nucleated final\nstates. This emergent phase, characterized by its lack of spin order due to the\ncompetition between the antiferromagnetic and ferromagnetic interactions, leads\nto suppression of the dynamic aspect of the transition, generating a static\nmixed-phase-morphology. Understanding and controlling the transition process at\nthis spatial scale is critical to optimizing functional device capabilities.",
        "positive": "A knitting algorithm for calculating Green functions in quantum systems: We propose a fast and versatile algorithm to calculate local and transport\nproperties such as conductance, shot noise, local density of state or local\ncurrents in mesoscopic quantum systems. Within the non equilibrium Green\nfunction formalism, we generalize the recursive Green function technique to\ntackle multiterminal devices with arbitrary geometries. We apply our method to\nanalyze two recent experiments: an electronic Mach-Zehnder interferometer in a\n2D gas and a Hall bar made of graphene nanoribbons in quantum Hall regime. In\nthe latter case, we find that the Landau edge state pinned to the Dirac point\ngets diluted upon increasing carrier density."
    },
    {
        "anchor": "Modulation of Schottky barrier height in graphene/MoS2/metal vertical\n  heterostructure with large current ON-OFF ratio: Detail transport properties of graphene/MoS2/metal vertical heterostructure\nhave been investigated. The van der Waals interface between the graphene and\nMoS2 exhibits Schottky barrier. The application of gate voltage to the graphene\nlayer enables us to modulate the Schottky barrier height; thus gives rise to\nthe control of the current flow across the interface. By analyzing the\ntemperature dependence of the conductance, the modulation of Schottky barrier\nheight {\\Delta}{\\phi} has been directly determined. We observed significant\nMoS2 layer number dependence of {\\Delta}{\\phi}. Moreover, we demonstrate that\nthe device which shows larger {\\Delta}{\\phi} exhibits larger current\nmodulation; this is consistent with the fact that the transport of these\ndevices is dominated by graphene/MoS2 Schottky barrier.",
        "positive": "Effect of edge defects on band structure of zigzag graphene nanoribbons: In this article, we report band structure studies of zigzag graphene\nnanoribbons (ZGNRs) on introducing defects (sp_3 hybridized carbon atoms) in\ndifferent concentrations at edges by varying the ratio of sp_3 to sp_2\nhybridized carbon atoms. On the basis of theoretical analyses, band gap values\nof ZGNRs are found to be strongly dependent on relative arrangement of sp3 to\nsp2 hybridized carbon atoms at the edges for a defect concentration; so the\nfindings would greatly help in understanding band gap of nanoribbons for their\nelectronic applications."
    },
    {
        "anchor": "Radio frequency charge sensing in InAs nanowire double quantum dots: We demonstrate charge sensing of an InAs nanowire double quantum dot (DQD)\ncoupled to a radio frequency (rf) circuit. We measure the rf signal reflected\nby the resonator using homodyne detection. Clear single dot and DQD behavior\nare observed in the resonator response. rf-reflectometry allows measurements of\nthe DQD charge stability diagram in the few-electron regime even when the dc\ncurrent through the device is too small to be measured. For a signal-to-noise\nratio of one, we estimate a minimum charge detection time of 350 microseconds\nat interdot charge transitions and 9 microseconds for charge transitions with\nthe leads.",
        "positive": "Dynamic Nuclear Overhauser Shifts in Larmor beats from a quantum well: The significance of nuclear spin polarisation in time-resolved optical\nstudies of III-V semiconductors is addressed. Electron Larmor beats in\npump-probe reflectivity from a GaAs/AlGaAs quantum well show Overhauser shift\nof 0.7 T due to accumulated nuclear polarisation <I>/I=0.065. This leads to\nprecision values of electron g-factor, elucidates nuclear spin pumping and\ndiffusion mechanisms in quantum wells and informs discussion of implications\nfor spin-electronics and transport."
    },
    {
        "anchor": "Quantum buckling in metal-organic framework materials: Metal organic frameworks are porous materials composed of metal ions or\nclusters coordinated by organic molecules. As a response to applied uniaxial\npressure, molecules of straight shape in the framework start to buckle. Under\nsufficiently low temperatures, this buckling is of quantum nature, described by\na superposition of degenerate buckling states. Buckling states of adjacent\nmolecules couple in a transverse Ising type behavior. On the example of the\nmetal organic framework topology MOF-5 we derive the phase diagram under\napplied strain, showing a normal, a parabuckling, and a ferrobuckling phase. At\nzero temperature, quantum phase transitions between the three phases can be\ninduced by strain. This novel type of order opens a new path towards strain\ninduced quantum phases.",
        "positive": "Graphene nanodevices: bridging nanoelectronics and subwavelength optics: The unconventional properties of graphene, with a massless Dirac band\ndispersion and large coherence properties, have raised a large interest for\napplications in nanoelectronics. In this work, we emphasize that graphene two\ndimensional character combined with current standard lithography processes\nallow to achieve devices smaller than the Dirac electrons wavelength. In this\nregime, we demonstrate that the electronic properties present deep analogies\nwith subwavelength optics phenomena. We describe the rich transport physics in\ngraphene-based nanodevices through optical analogies: From the Bethe and\nKirchhoff-like diffraction patterns in the conductance of graphene slits to the\nFabry-Perot oscillations of the conductance in nanoribbons. We introduce the\nconcept of {\\it electronic diffraction barriers}, which transmission cancels at\nthe Dirac point. This gives central insight in the properties of Graphene\nsubwavelength devices including nanoelectronics standard systems, such as\nquantum dots. As an application we propose a new type of quantum dots, namely\nfunctionalized subwavelength quantum dots, which could be used as molecular\nspin valves."
    },
    {
        "anchor": "Lifting topological protection in a quantum spin Hall insulator by edge\n  coupling: The scientific interest in two-dimensional topological insulators (2D TIs) is\ncurrently shifting from a more fundamental perspective to the exploration and\ndesign of novel functionalities. Key concepts for the use of 2D TIs in\nspintronics are based on the topological protection and spin-momentum locking\nof their helical edge states. In this study we present experimental evidence\nthat topological protection can be (partially) lifted by pairwise coupling of\n2D TI edges in close proximity. Using direct wave function mapping via scanning\ntunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled\ntopological edges in the 2D TI bismuthene. The latter situation is realized by\nnatural lattice line defects and reveals distinct quasi-particle interference\n(QPI) patterns, identified as electronic Fabry-P\\'erot resonator modes. In\ncontrast, free edges show no sign of any single-particle backscattering. These\nresults pave the way for novel device concepts based on active control of\ntopological protection through inter-edge hybridization for, e.g., electronic\nFabry-P\\'erot interferometry.",
        "positive": "Majoranas with and without a 'character': hybridization, braiding and\n  Majorana number: In this paper we demonstrate under what conditions a pseudo-spin degree of\nfreedom or character can be ascribed to the Majorana bound states (MBS) which\ncan be created at the end of one dimensional non-interacting systems,\ncorresponding to D, DIII and BDI in the usual classification scheme. We have\nfound that such a character is directly related to the class of the topological\nsuperconductor and its description by a $\\mathbb{Z}$, rather than a\n$\\mathbb{Z}_2$, invariant which corresponds to the BDI class. We have also\nfound that the DIII case with mirror symmetry, which supports multiple MBS, is\nin fact equivalent to the BDI class with an additional time-reversal symmetry.\nIn all cases where a character can be given to the Majorana states we show how\nto construct the appropriate operator explicitly in various examples. We also\nexamine the consequences of the Majorana character by considering possible\nhybridization of MBS brought into proximity and find that two MBS with the same\ncharacter do not hybridize. Finally, we show that having this character or not\nhas no consequence on the braiding properties of MBS."
    },
    {
        "anchor": "Transmission Properties of the oscillating delta-function potential: We derive an exact expression for the transmission amplitude of a particle\nmoving through a harmonically driven delta-function potential by using the\nmethod of continued-fractions within the framework of Floquet theory. We prove\nthat the transmission through this potential as a function of the incident\nenergy presents at most two real zeros, that its poles occur at energies\n$n\\hbar\\omega+\\varepsilon^*$ ($0<Re(\\varepsilon^*)<\\hbar\\omega$), and that the\npoles and zeros in the transmission amplitude come in pairs with the distance\nbetween the zeros and the poles (and their residue) decreasing with increasing\nenergy of the incident particle. We also show the existence of non-resonant\n\"bands\" in the transmission amplitude as a function of the strength of the\npotential and the driving frequency.",
        "positive": "Nonreciprocal Coulomb Drag between Quantum Wires in the quasi-1D regime: Coulomb drag experiments have been an essential tool to study strongly\ninteracting low-dimensional systems. Historically, this effect has been\nexplained in terms of momentum transfer between electrons in the active and the\npassive layer. Here, we report Coulomb drag measurements between laterally\ncoupled GaAs/AlGaAs quantum wires in the multiple 1D sub-band regime that break\nOnsager's reciprocity upon both layer and current direction reversal, in\ncontrast to prior 1D Coulomb drag results. The drag signal shows nonlinear I-V\ncharacteristics, which are well characterized by a third-order polynomial fit.\nThese findings are qualitatively consistent with a rectified drag signal\ninduced by charge fluctuations. However, the nonmonotonic temperature\ndependence of this drag signal suggests that strong electron-electron\ninteractions, expected within the Tomonaga-Luttinger liquid framework, remain\nimportant and standard interaction models are insufficient to capture the\nqualitative nature of rectified 1D Coulomb drag."
    },
    {
        "anchor": "Magnetoelectricity in two-dimensional materials: Since the initial isolation of few-layer graphene, a plethora of\ntwo-dimensional atomic crystals has become available, covering almost all known\nmaterials types including metals, semiconductors, superconductors, ferro- and\nantiferromagnets. These advances have augmented the already existing variety of\ntwo-dimensional materials that are routinely realized by quantum confinement in\nbulk-semiconductor heterostructures. This review focuses on the type of\nmaterial for which two-dimensional realizations are still being actively\nsought: magnetoelectrics. We present an overview of current theoretical\nexpectation and experimental progress towards fabricating low-dimensional\nversions of such materials that can be magnetized by electric charges and\npolarized electrically by an applied magnetic field - unusual electromagnetic\nproperties that could be the basis for various useful applications. The\ninterplay between spatial confinement and magnetoelectricity is illustrated\nusing the paradigmatic example of magnetic-monopole fields generated by\nelectric charges in or near magnetoelectric media. For the purpose of this\ndiscussion, the image-charge method familiar from electrostatics is extended to\nsolve the boundary-value problem for a magnetoelectric medium in the\nfinite-width slab geometry using image dyons, i.e., point objects having both\nelectric and magnetic charges. We discuss salient features of the\nmagnetoelectrically induced fields arising in the thin-width limit.",
        "positive": "A Transfer Hamiltonian approach in self-consistent field regime for\n  transport in arbitrary quantum dot arrays: A transport methodology to study the electron transport between quantum dots\narrays based in Transfer Hamiltonian approach is presented. The interactions\nbetween the quantum dots and between the quantum dots and the electrodes are\nintroduced by transition rates and capacitive couplings. The effects of the\nlocal potential are computed within the self-consistent field regime. The model\nhas been developed and expressed in a matrix form in order to make it\nextendable to larger systems. Transport through several quantum dot\nconfigurations have been studied in order to validate the model. Despite the\nsimplicity of the model, well-known effects are satisfactorily reproduced and\nexplained. The results qualitatively agree with other results obtained using\nmore complex theoretical approaches."
    },
    {
        "anchor": "Engineering Fragile Topology in Photonic Crystals: Topological Quantum\n  Chemistry of Light: In recent years, there have been rapid advances in the parallel fields of\nelectronic and photonic topological crystals. Topological photonic crystals in\nparticular show promise for coherent transport of light and quantum information\nat macroscopic scales. In this work, we apply for the first time the recently\ndeveloped theory of \"Topological quantum chemistry\" to the study of band\nstructures in photonic crystals. This method allows us to design and diagnose\ntopological photonic band structures using only group theory and linear\nalgebra. As an example, we focus on a family of crystals formed by elliptical\nrods in a triangular lattice. We show that the symmetry of Bloch states in the\nBrillouin zone can determine the position of the localized photonic wave\npackets describing groups of bands. By modifying the crystal structure and\ninverting bands, we show how the centers of these wave packets can be moved\nbetween different positions in the unit cell. Finally, we show that for shapes\nof dielectric rods, there exist isolated topological bands which do not admit a\nwell-localized description, representing the first physical instance of\n\"fragile\" topology in a truly noninteracting system. Our work demonstrates how\nphotonic crystals are the natural platform for the future experimental\ninvestigation of fragile topological bands.",
        "positive": "Effect of uniaxial strain on plasmon excitations in graphene: Uniaxial strain is known to modify significantly the electronic properties of\ngraphene, a carbon single layer of atomic width. Here, we study the effect of\napplied strain on the composite excitations arising from the coupling of charge\ncarriers and plasmons in graphene, i.e. the plasmarons. Specifically, we\npredict that the plasmaron energy dispersion, which has been recently observed\nexperimentally in unstrained graphene, is shifted and broadened by applied\nuniaxial strain. Thus, strain constitutes an additional parameter which may be\nuseful to tune graphene properties in plasmaronic devices."
    },
    {
        "anchor": "An Origin of Dzyaloshinskii-Moriya Interaction at Graphene-Ferromagnet\n  Interfaces Due to the Intralayer RKKY/BR Interaction: We present a theory of both the itinerant carrier-mediated RKKY interaction\nand the virtual excitations-mediated Bloembergen-Rowland (BR) interaction\nbetween magnetic moments in graphene induced by proximity effect with a\nferromagnetic film. We show that the RKKY/BR interaction consists of the\nHeisenberg, Ising, and Dzyaloshinskii-Moriya (DM) terms. In the case of the\nnearest distance, we estimate the DM term from the RKKY/BR interaction is about\n0.13 meV for the graphene/Co interface, which is consistent with the\nexperimental result of DM interaction $0.16 \\pm 0.05$ meV. Our calculations\nindicate that the intralayer RKKY/BR interaction may be a possible physical\norigin of the DM interaction in the graphene-ferromagnet interface. This work\nprovides a new perspective to comprehend the DM interaction in\ngraphene/ferromagnet systems.",
        "positive": "Thin film epitaxial [111] Co$_{50}$Pt$_{50}$: Structure, magnetisation,\n  and spin polarisation: Ferromagnetic films with perpendicular magnetic anisotropy are of interest in\nspintronics and superconducting spintronics. Perpendicular magnetic anisotropy\ncan be achieved in thin ferromagnetic multilayer structures, when the\nanisotropy is driven by carefully engineered interfaces. Devices with multiple\ninterfaces are disadvantageous for our application in superconducting\nspintronics, where the current perpendicular to plane is affected by the\ninterfaces. Robust intrinsic PMA can be achieved in certain Co$_x$Pt$_{100-x}$\nalloys and compounds at any thickness, without increasing the number of\ninterfaces. Here, we grow equiatomic Co$_{50}$Pt$_{50}$ and report a\ncomprehensive study on the structural, magnetic, and spin-polarisation\nproperties in the $L1_1$ and $L1_0$ ordered compounds. Primarily, interest in\nCo$_{50}$Pt$_{50}$ has been in the $L1_0$ crystal structure, where layers of Pt\nand Co are stacked alternately in the [100] direction. There has been less work\non $L1_1$ crystal structure, where the stacking is in the [111] direction. For\nthe latter $L1_1$ crystal structure, we find magnetic anisotropy perpendicular\nto the film plane. For the former $L1_0$ crystal structure, the magnetic\nanisotropy is perpendicular to the [100] plane, which is neither in-plane or\nout-of-plane in our samples. We obtain a value for the ballistic spin\npolarisation of the $L1_1$ and $L1_0$ Co$_{50}$Pt$_{50}$ to be $47\\pm3\\%$."
    },
    {
        "anchor": "Repulsive Casimir force from a Majorana zero-mode: Fu and Kane have taught us that a Majorana zero-mode appears on the quantum\nspin Hall edge at the interface with a superconductor. If a magnetic scatterer\nis placed on the edge, the zero-point energy of massless edge excitations\nexerts a force on the scatterer. This is the fermionic analogue of the\nelectromagnetic Casimir effect. We show that the Majorana zero-mode produces a\nrepulsive Casimir force, pushing the scatterer away from the superconductor.\nUnlike some other signatures of Majorana zero-modes, the repulsive Casimir\nforce is directly tied to the topological invariant of the system (the sign of\nthe determinant of the reflection matrix from the superconductor).",
        "positive": "Molecular Electronics: From Physics to Computing: Even if Moore's Law continues to hold, it will take about 250 years to fill\nthe performance gap between present-day computer and the ultimate computer\ndetermined from the laws of physics alone. Information processing technology in\nthe post-CMOS era will likely consist of a heterogeneous set of novel device\ntechnologies that span a broad range of materials, operational principles, data\nrepresentations, logic systems and architectures. Molecular nanostructures\npromise to occupy a prominent role in any attempt to extend charge-based device\ntechnology beyond the projected limits of CMOS scaling. We discuss the\npotentials and challenges of molecular electronics and identify the fundamental\nknowledge gap that needs to be addressed for a successful introduction of\nmolecule-enabled computing technology"
    },
    {
        "anchor": "Permeability and kinetic coefficients for mesoscale BCF surface step\n  dynamics: discrete 2D deposition-diffusion equation analysis: A discrete version of deposition-diffusion equations appropriate for\ndescription of step flow on a vicinal surface is analyzed for a two-dimensional\ngrid of adsorption sites representing the stepped surface and explicitly\nincorporating kinks along the step edges. Model energetics and kinetics\nappropriately account for binding of adatoms at steps and kinks, distinct\nterrace and edge diffusion rates, and possibly asymmetric barriers for\nattachment to steps. Analysis of adatom attachment fluxes as well as limiting\nvalues of adatom densities at step edges for non-uniform deposition scenarios\nallows determination of both permeability and kinetic coefficients. Behavior of\nthese quantities is assessed as a function of key system parameters including\nkink density, step attachment barriers, and the step edge diffusion rate.",
        "positive": "Spin Properties of Low Density One-Dimensional Wires: We report conductance measurements of a ballistic one-dimensional (1D) wire\ndefined in the lower two-dimensional electron gas of a GaAs/AlGaAs double\nquantum well. At low temperatures there is an additional structure at\n$0.7(2e^2/h)$ in the conductance, which tends to $e^2/h$ as the electron\ndensity is decreased. We find evidence for complete spin polarization in a\nweakly disorderd 1D wire at zero magnetic field through the observation of a\nconductance plateau at $e^2/h$, which strengthens in an in-plane magnetic field\nand disappears with increasing electron density. In all cases studied, with\nincreasing temperature structure occurs at $0.6(2e^2/h)$. We suggest that the\n0.7 structure is a many-body spin state excited out of, either the\nspin-polarized electron gas at low densities, or the spin-degenerate electron\ngas at high densities."
    },
    {
        "anchor": "Analytical Charge-Control Model for DH-HEMT: A new and simple analytical charge-control model of the two-dimensional\nelectron gas of a double-heterojunction AlGaAs/GaAs/AlGaAs HEMT is described.\nIt is found that, despite its simplicity, the charge-control model gives an\naccurate description of the device operation for a wide range of physical\nparameters. The validity of the analytical model is supported by the calculated\nresults of the self-consistent quantum mechanical model and agrees with\npreviously reported theoretical and experimental data. The influence of some\nphysical parameters on the device performance is also discussed.",
        "positive": "Semimetal-Monolayer Transition Metal Dichalcogenides Photodetectors for\n  Wafer-Scale Ultraviolet Photonics: Atomically thin two-dimensional (2D) transition metal dichalcogenides (TMDs),\nsuch as MoS$_2$, are promising candidates for nanoscale photonics because of\nstrong-light matter interactions. However, Fermi level pinning due to\nmetal-induced gap (MIGS) states at the metals-monolayer MoS$_2$ interface\nlimits the application of optoelectronic devices based on conventional metals\nbecause of the high contact resistance of the Schottky contacts. On the other\nhand, a semimetal-TMD-semimetal device can overcome this limitation, where the\nMIGS are sufficiently suppressed and can result in ohmic contacts. Here we\ndemonstrate the optoelectronic performance of a bismuth-monolayer (1L)\nMoS$_2$-bismuth device with ohmic electrical contacts and extraordinary\noptoelectronic properties. To address the wafer-scale production, we grew full\ncoverage 1L MoS$_2$ by using chemical vapor deposition method. We measured high\nphotoresponsivity of 300 A/W in the UV regime at 77 K, which translates into an\nexternal quantum efficiency (EQE) ~ 1000 or $10^5$%. We found that the 90% rise\ntime of our devices at 77 K is 0.1 ms, which suggests that the current devices\ncan operate at the speed of ~ 10 kHz. The combination of large-array device\nfabrication, high sensitivity, and high-speed response offers great potential\nfor applications in photonics that includes integrated optoelectronic circuits."
    },
    {
        "anchor": "Theory of spin noise in nanowires: We develop a theory of spin noise in semiconductor nanowires considered as\nprospective elements for spintronics. In these structures spin-orbit coupling\ncan be realized as a random function of coordinate correlated on the spatial\nscale of the order of 10 nm. By analyzing different regimes of electron\ntransport and spin dynamics, we demonstrate that the spin relaxation can be\nvery slow and the resulting noise power spectrum increases algebraically as\nfrequency goes to zero. This effect makes spin effects in nanowires best\nsuitable for studies by rapidly developing spin-noise spectroscopy.",
        "positive": "Exact Solution of Two-Dimensional Screened Donor State in a Magnetic\n  Field: The use of Levi-Civita transformation allows us to formulate the problem of\ntwo-dimensional screened donor states in a magnetic field as that of\ntwo-dimensional anharmonic oscillator. Therefore, the operator method can be\ndirectly used for the first problem and the exact solutions of Schrodinger\nequation are obtained correspondently. In our approach, wave-functions are\nconstructed in the representation of annihilation and creation operators, which\npermits one to use purely algebraic method in further calculations of other\ncharacteristics. The considered problem is related to the motion of 2D electron\ngas in GaAs/AlGaAs multiple-quantum well structures with the presence of a\nmagnetic field, which continues to provide new and fascinating phenomena."
    },
    {
        "anchor": "Fermionic Lensing in Smooth Graphene P-N Junctions: Focusing of electron waves in graphene p-n junctions is a striking\nmanifestation of fermionic negative refraction. We analyze lensing in smooth\np-n junctions and find that it differs in several interesting ways from that in\nthe previously studied sharp p-n junctions. Most importantly, while the overall\nnegative-refraction behavior remains unchanged, the image at the focal point\nundergoes additional broadening due to Klein tunneling in the junction. We\ndevelop a theory of image broadening and estimate the effect for practically\ninteresting system parameter values.",
        "positive": "Spin Hall Induced Magnetization Dynamics in Multiferroic Tunnel Junction: The combination of spin-orbit coupling driven effects and multiferroic\ntunneling properties was explored experimentally in thin Pt/Co/BTO/LSMO\nmultilayers. The presence of a Pt heavy metal allows for the spin\ncurrent-induced magnetization precession of Co upon radio-frequency charge\ncurrent injection. The utilization of a BTO ferroelectric tunnel barrier\nseparating the Co and LSMO ferromagnetic electrodes gives rise to both\ntunneling-magnetoresistance and electroresistance. Using the spin-orbit torque\nferromagnetic resonance, the maganetization dynamics of the Co/Pt bilayers was\nstudied at room temperature. Unexpectedly the magnetization dynamics study in\nthe same geometry performed at low temperature reveals the existence of both Co\nand LSMO resonance peaks indicating efficient spin current generation both\nusing the spin Hall effect in Pt and spin pumping in LSMO that tunnel via the\nBTO barrier."
    },
    {
        "anchor": "Electric-field fluctuations as the cause of spectral instabilities in\n  colloidal quantum dots: Spectral diffusion (SD) represents a substantial obstacle towards\nimplementation of solid-state quantum emitters as a source of indistinguishable\nphotons. By performing high-resolution emission spectroscopy for individual\ncolloidal quantum dots at cryogenic temperatures, we prove the causal link\nbetween the quantum-confined Stark effect and SD. Statistically analyzing the\nwavelength of emitted photons, we show that increasing the sensitivity of the\ntransition energy to an applied electric field results in amplified spectral\nfluctuations. This relation is quantitatively fit to a straightforward model,\nindicating the presence of a stochastic electric field on a microscopic scale\nwhose standard deviation is 9 kV/cm, on average. Compensating the commonly\nobserved intrinsic electric bias with an external one, we find that SD can be\nsuppressed by up to a factor of three in CdSe/CdS core/shell nanorods. The\ncurrent method will enable the study of SD in multiple types of quantum\nemitters, such as solid-state defects or organic lead-halide perovskite quantum\ndots, for which spectral instability is a critical barrier for applications in\nquantum sensing.",
        "positive": "Non-Markovian dynamics of a localized electron spin due to the hyperfine\n  interaction: We review our theoretical work on the dynamics of a localized electron spin\ninteracting with an environment of nuclear spins. Our perturbative calculation\nis valid for arbitrary polarization p of the nuclear spin system and arbitrary\nnuclear spin I in a sufficiently large magnetic field. In general, the electron\nspin shows rich dynamics, described by a sum of contributions with exponential\ndecay, non-exponential decay, and undamped oscillations. We have found an\nabrupt crossover in the long-time spin dynamics at a critical shape and\ndimensionality of the electron envelope wave function. We conclude with a\ndiscussion of our proposed scheme to measure the relevant dynamics using a\nstandard spin-echo technique."
    },
    {
        "anchor": "Manipulating topology in tailored artificial graphene nanoribbons: Topological phases of matter give rise to exotic physics that can be\nleveraged for next generation quantum computation and spintronic devices. Thus,\nthe search for topological phases and the quantum states that they exhibit have\nbecome the subject of a massive research effort in condensed matter physics.\nTopologically protected states have been produced in a variety of systems,\nincluding artificial lattices, graphene nanoribbons (GNRs) and bismuth\nbilayers. Despite these advances, the real-time manipulation of individual\ntopological states and their relative coupling, a necessary feature for the\nrealization of topological qubits, remains elusive. Guided by first-principles\ncalculations, we spatially manipulate robust, zero-dimensional topological\nstates by altering the topological invariants of quasi-one-dimensional\nartificial graphene nanostructures. This is achieved by positioning carbon\nmonoxide molecules on a copper surface to confine its surface state electrons\ninto artificial atoms positioned to emulate the low-energy electronic structure\nof graphene derivatives. Ultimately, we demonstrate control over the coupling\nbetween adjacent topological states that are finely engineered and simulate\ncomplex Hamiltonians. Our atomic synthesis gives access to an infinite range of\nnanoribbon geometries, including those beyond the current reach of synthetic\nchemistry, and thus provides an ideal platform for the design and study of\nnovel topological and quantum states of matter.",
        "positive": "Ballistic reflection at a side-gate in a\n  superconductor-semiconductor-superconductor structure: We have fabricated a sub-micron-sized structure consisting of an InAs-based\n2DEG, two narrow Nb leads and a gate, where the indirect ballistic transport\nbetween the non-oppositely superconducting contacts can be controlled by the\nvoltage applied to the gate. This new kind of tuneable junction can be used for\napplications and allows several fundamental questions related to the transport\nmechanism to be studied. First results of experiments carried out in this\nrespect are presented."
    },
    {
        "anchor": "Resonant tunnelling and negative differential conductance in graphene\n  transistors: The chemical stability of graphene and other free-standing two-dimensional\ncrystals means that they can be stacked in different combinations to produce a\nnew class of functional materials, designed for specific device applications.\nHere we report resonant tunnelling of Dirac fermions through a boron nitride\nbarrier, a few atomic layers thick, sandwiched between two graphene electrodes.\nThe resonant peak in the device characteristics occurs when the electronic\nspectra of the two electrodes are aligned. The resulting negative differential\nconductance persists up to room temperature and is gate voltage-tuneable due to\ngraphene's unique Dirac-like spectrum. Whereas conventional resonant tunnelling\ndevices comprising a quantum well sandwiched between two tunnel barriers are\ntens of nanometres thick, the tunnelling carriers in our devices cross only a\nfew atomic layers, offering the prospect of ultra-fast transit times. This\nfeature, combined with the multi-valued form of the device characteristics, has\npotential for applications in high-frequency and logic devices.",
        "positive": "Design of graphene waveguide: Effect of edge orientation and waveguide\n  configuration: Electron transport in a graphene quantum well can be analogous to photon\ntransmission in an optical fiber. In this work, we present a detailed\ntheoretical analysis to study the transport characteristics of graphene\nwaveguides under the influence of different edge orientations. Non-equilibrium\nGreen's function approach in combination with tight-binding Hamiltonian has\nbeen utilized to investigate the conductance properties of straight armchair\nand zigzag oriented graphene waveguides. Conductance plateaus at integer steps\nof $4e^2/h$ have been observed in both orientations while the zigzag oriented\nwaveguides present a wider first quantized plateau compared to that in the\narmchair oriented ones. Using various geometric and physical parameters,\nincluding side-barrier and waveguide width, and the metallic properties of\nterminals, we investigate the conductance profile of waveguides. In addition to\nthe observation of valley-symmetry in both edge orientations, this article\nexplores the critical influence of drain contacts on waveguide conductance.\nFurthermore, we extended our transport study to three different highly bent\nwaveguide configurations, such as U-shape, L-shape and split-shape waveguides,\nin order to explore their applications in graphene-based ballistic integrated\ncircuit devices. In the end, we also calculated the conductance of larger\ngraphene waveguides using the scalable tight-binding model, in order to compare\nthe results obtained from the original model."
    },
    {
        "anchor": "Chirality Dependence of the $K$-Momentum Dark Excitons in Carbon\n  Nanotubes: Using a collection of twelve semiconducting carbon nanotube samples, each\nhighly enriched in a single chirality, we study the chirality dependence of the\n$K$-momentum dark singlet exciton using phonon sideband optical spectroscopy.\nMeasurements of bright absorptive and emissive sidebands of this finite\nmomentum exciton identify its energy as 20 - 38 meV above the bright singlet\nexciton, a separation that exhibits systematic dependencies on tube diameter,\n$2n+m$ family, and semiconducting type. We present calculations that explain\nhow chiral angle dependence in this energy separation relates to the Coulomb\nexchange interaction, and elaborate the dominance of the $K_{A_1'}$ phonon\nsidebands over the zone-center phonon sidebands over a wide range of\nchiralities. The Kataura plot arising from these data is qualitatively well\ndescribed by theory, but the energy separation between the sidebands shows a\nlarger chiral dependence than predicted. This latter observation may indicate a\nlarger dispersion for the associated phonon near the $K$ point than expected\nfrom finite distance force modeling.",
        "positive": "1/f Noise from the Laws of Thermodynamics for Finite-Size Fluctuations: Computer simulations of the Ising model exhibit white noise if thermal\nfluctuations are governed by Boltzmann's factor alone; whereas we find that the\nsame model exhibits 1/f noise if Boltzmann's factor is extended to include\nlocal alignment entropy to all orders. We show that this nonlinear correction\nmaintains maximum entropy during equilibrium fluctuations. Indeed, as with the\nusual resolution of Gibbs' paradox that avoids net entropy reduction during\nreversible processes, the correction yields the statistics of indistinguishable\nparticles. The correction also ensures conservation of energy if an\ninstantaneous contribution from local entropy is included. Thus, a common\nmechanism for 1/f noise comes from assuming that finite-size fluctuations\nstrictly obey the laws of thermodynamics, even in small parts of a large\nsystem. Empirical evidence for the model comes from its ability to match the\nmeasured temperature dependence of the spectral-density exponents in several\nmetals, and to show non-Gaussian fluctuations characteristic of nanoscale\nsystems."
    },
    {
        "anchor": "Quantum noise properties of multiphoton transitions in driven nonlinear\n  resonators: We investigate the quantum noise properties of a weakly nonlinear Duffing\nresonator in the deep quantum regime, where only few quanta are excited. This\nregime is dominated by the appearance of coherent multiphoton resonances in the\nnonlinear response of the resonator to the modulation. We determine simple\nexpressions for the photon noise spectrum and find that the multiphoton\nresonances also induces a multiple peak structure in that noise. When the\ncorresponding multiphoton Rabi oscillations are underdamped, zero temperature\nquantum fluctuations determine comparable populations of all quasienergy states\nwhich belong to a resonant multiphoton doublet. Most interestingly, the quantum\nfluctuations probe the multiphoton transitions by inducing several peaks in the\nnoise spectrum of the resonator observables. In particular, the noise of the\nphoton number contains complete information about the multiphoton states and\ntheir stationary populations via pairs of nearly symmetric peaks at opposite\nfrequencies. Their widths are determined by the damping of the Rabi\noscillations and their heights are proportional to the stationary nonequilbrium\npopulations. A finite detuning from a multiphoton resonance generates a\nquasielastic noise peak at zero frequency. In addition, we relate the\nstationary populations of the quasienergy states with an effective quantum\ntemperature and discuss the role of a finite temperature.",
        "positive": "Giant domain wall response of highly twinned ferroelastic materials: Many ferroelastic crystals display at sufficiently low measurement\nfrequencies a huge elastic softening below Tc which is caused by domain wall\nmotion. Materials range from perovskites to iron based superconductors and\nshape memory materials. We present a model - based on Landau-Ginzburg theory\nincluding long range elastic interaction between needle shaped ferroelastic\ndomains - to describe the observed superelastic softening. The theory predicts\nthat the domain wall contribution to the elastic susceptibility is different\nfor improper and proper ferroelastic materials. A test of the theory against\nexperimental data on SrTiO3, KMnF3, LaAlO3, La1-xNdxP5O14 and NH4HC2O4.1/2H2O\nyields excellent agreement."
    },
    {
        "anchor": "Tunable graphene-based polarizer: It is shown that an attenuated total reflection structure containing a\ngraphene layer can operate as a tunable polarizer of the electromagnetic\nradiation. The polarization angle is controlled by adjusting the voltage\napplied to graphene via external gate. The mechanism is based on the resonant\ncoupling of $p-$polarized electromagnetic waves to the surface\nplasmon-polaritons in graphene. The presented calculations show that, at\nresonance, the reflected wave is almost 100% $s-$polarized.",
        "positive": "Calculation of Cu/Ta interface electron transmission and effect on\n  conductivity in nanoscale interconnect technology: Resistivity augmentation in nanoscale metal interconnects is a performance\nlimiting factor in integrated circuits. Here we present calculations of\nelectron scattering and transmission at the interface between Cu interconnects\nand their barrier layers, in this case Ta. We also present a semiclassical\nmodel to predict the technological impact of this scattering and find that a\nbarrier layer can significantly decrease conductivity, consistent with\npreviously published measurements."
    },
    {
        "anchor": "Klein tunneling of the electronic states in the gate voltage modulated\n  skyrmion crystal: As a result of the Hund's coupling, the band structure of the conducting\nelectrons in the skyrmion crystal (SkX) shares similar topological properties\nwith that of graphene, such as its cone-like shape, nonzero band Chern number,\nedge states, and etc. In this work, we rigorously demonstrate that the Klein\ntunneling phenomena is also shared by these two. We use the Green's function\ntechnique and calculated the transmission probability of the electrons\ntunneling through an electrostatic barrier in the SkX expressed by the double\nexchange model. Numerical results of the SkX reproduced the Dirac model\nobtained by linear fitting the two-dimensional band structure of the SkX.",
        "positive": "Plasmon Standing Waves by Oxidation of Si(553)-Au: Self-assembled Au atomic wires on stepped Si surfaces are metallic, as\nevidenced by a one-dimensionally dispersing plasmonic excitation. Here we\ninvestigate the effects of oxidization on metallicity along such Au atomic\nwires on a regularly stepped Si(553) surface, by employing infrared absorption\nand high resolution electron energy loss spectroscopies. Our results indicate\nthat only the Si environment undergoes oxidation, which has a remarkably small\neffect on the plasmon dispersion. Only close to $k_{\\parallel}\\rightarrow 0$\nthe plasmon dispersion ends at increasingly higher energies as a function of\noxygen exposure, which is attributed to standing wave formation on small\nsections of Au wires generated by the introduction of O atoms as scattering\ncenters, not to electronic gap opening. This interpretation is in full\nagreement with the findings by infrared spectroscopy and with low energy\nelectron diffraction."
    },
    {
        "anchor": "Coulomb effects in semiconductor quantum dots: Coulomb correlations in the optical spectra of semiconductor quantum dots are\ninvestigated using a full-diagonalization approach. The resulting multi-exciton\nspectra are discussed in terms of the symmetry of the involved states.\nCharacteristic features of the spectra like the nearly equidistantly spaced\ns-shell emission lines and the approximately constant p-shell transition\nenergies are explained using simplified Hamiltonians that are derived taking\ninto account the relative importance of various interaction contributions.\nComparisons with previous results in the literature and their interpretation\nare made.",
        "positive": "Failure of the Wiedemann-Franz Law in Mesoscopic Conductors: We study the effect of mesoscopic fluctuations on the validity of the\nWiedemann--Franz (WF) law for quasi-one-dimensional metal wires and open\nquantum dots. At temperatures much less than the generalized Thouless energy,\nE_c, the WF law is satisfied for each specific sample but as the temperature is\nraised through E_c a sample-specific correction to the WF law of order 1/g\nappears (g is the dimensionless conductance) and then tends to zero again at\nhigh temperatures. The mesoscopic violation of the Weidemann-Franz law is even\nmore pronounced in a ring geometry, for which Lorenz number exhibits h/e\nflux-periodic Aharonov-Bohm oscillations."
    },
    {
        "anchor": "Signatures of magnon hydrodynamics in an atomically-thin ferromagnet: Strong interactions between particles can lead to emergent collective\nexcitations. These phenomena have been extensively established in electronic\nsystems, but are also expected to occur for gases of neutral particles like\nspin waves, also known as magnons, in a ferromagnet. In a hydrodynamic regime\nwhere magnons are strongly interacting, they can form a slow collective density\nmode -- in analogy to sound waves in water -- with characteristic low-frequency\nsignatures. While such a mode has been predicted in theory, its signatures have\nyet to be observed experimentally. In this work, we isolate atomically-thin\nsheets of ferromagnetic CrCl$_3$ where magnon interactions are strong, and\ndevelop a technique to measure its collective magnon dynamics via the quantum\ncoherence of nearby Nitrogen-Vacancy (NV) centers in diamond. We find that the\nthermal magnetic fluctuations generated by CrCl$_3$ exhibit an anomalous\ntemperature-dependence, whereby fluctuations increase upon decreasing\ntemperature. Our analysis reveals that this anomalous trend is a consequence of\nthe damping rate of a low-energy magnon sound mode which sharpens as magnon\ninteractions increase with increasing temperature, providing a first glimpse of\nthe magnon hydrodynamic regime.",
        "positive": "Long-range spin-wave propagation in transversely magnetized nano-scaled\n  conduits: Magnonics attracts increasing attention in the view of novel low-energy\ncomputation technologies based on spin waves. Recently, spin-wave propagation\nin longitudinally magnetized nano-scaled spin-wave conduits was demonstrated,\nproving the fundamental feasibility of magnonics at the sub-100 nm scale.\nTransversely magnetized nano-conduits, which are of great interest in this\nregard as they offer a large group velocity and a potentially chirality-based\nprotected transport of energy, have not yet been investigated due to their\ncomplex internal magnetic field distribution. Here, we present a study of\npropagating spin waves in a transversely magnetized nanoscopic yttrium iron\ngarnet conduit of 50 nm width. Space and time-resolved micro-focused\nBrillouin-light-scattering spectroscopy is employed to measure the spin-wave\ngroup velocity and decay length. A long-range spin-wave propagation is observed\nwith a decay length of up to (8.0+-1.5) {\\mu}m and a large spin-wave lifetime\nof up to (44.7+-9.1) ns. The results are supported with micromagnetic\nsimulations, revealing a single-mode dispersion relation in contrast to the\ncommon formation of localized edge modes for microscopic systems. Furthermore,\na frequency non-reciprocity for counter-propagating spin waves is observed in\nthe simulations and the experiment, caused by the trapezoidal cross-section of\nthe structure. The revealed long-distance spin-wave propagation on the\nnanoscale is particularly interesting for an application in spin-wave devices,\nallowing for long-distance transport of information in magnonic circuits, as\nwell as novel low-energy device architectures."
    },
    {
        "anchor": "Interplay between Aharonov-Bohm interference and parity selective\n  tunneling in zigzag graphene nanoribbon rings: We report a numerical study on Aharonov-Bohm (AB) effect and parity selective\ntunneling in pn junctions based on zigzag graphene nanoribbon rings. We find\nthat when applying a magnetic field to the ring, the AB interference can\nreverse the parity symmetry of incoming waves and hence can strongly modulate\nthe parity selective transmission through the system. Therefore, the\ntransmission between two states of different parity exhibits the AB\noscillations with a \\pi-phase shift, compared to the case of states of same\nparity. On this basis, it is shown that interesting effects such as giant (both\npositive and negative) magnetoresistance and strong negative differential\nconductance can be achieved in this structure. Our study thus presents a new\nproperty of the AB interference, which could be helpful to further understand\nthe transport properties of graphene mesoscopic-systems.",
        "positive": "Electrons imitating light: Frustrated supercritical collapse in charged\n  arrays on graphene: The photon-like electronic dispersion of graphene bestows its charge carriers\nwith unusual confinement properties that depend strongly on the geometry and\nstrength of the surrounding potential. Here we report bottom-up synthesis of\natomically-precise one-dimensional (1D) arrays of point charges aimed at\nexploring supercritical confinement of carriers in graphene for new geometries.\nThe arrays were synthesized by arranging F4TCNQ molecules into a 1D lattice on\nback-gated graphene devices, allowing precise tuning of both the molecular\ncharge state and the array periodicity. Dilute arrays of ionized F4TCNQ\nmolecules are seen to behave like isolated subcritical charges but dense arrays\nshow emergent supercriticality. In contrast to compact supercritical clusters,\nextended 1D charge arrays exhibit both supercritical and subcritical\ncharacteristics and belong to a new physical regime termed frustrated\nsupercritical collapse. Here carriers in the far-field are attracted by a\nsupercritical charge distribution, but have their fall to the center frustrated\nby subcritical potentials in the near-field, similar to the trapping of light\nby a dense cluster of stars in general relativity."
    },
    {
        "anchor": "Inducing electron spin coherence in GaAs quantum well waveguides: Spin\n  coherence without spin precession: Electron spin coherence is induced via light-hole transitions in a quantum\nwell waveguide without either an external or internal DC magnetic field. In the\nabsence of spin precession, the induced spin coherence is detected through\neffects of quantum interference in the spectral domain coherent nonlinear\noptical response. We interpret the experimental results qualitatively using a\nsimple few-level model with only the optical transition selection rule as its\nbasic ingredients.",
        "positive": "Avalanches and Criticality in Driven Magnetic Skyrmions: We show using numerical simulations that slowly driven skyrmions interacting\nwith random pinning move via correlated jumps or avalanches. The avalanches\nexhibit power law distributions in their duration and size, and the average\navalanche shape for different avalanche durations can be scaled to a universal\nfunction, in agreement with theoretical predictions for systems in a\nnonequilibrium critical state. A distinctive feature of skyrmions is the\ninfluence of the non-dissipative Magnus term. When we increase the ratio of the\nMagnus term to the damping term, a change in the universality class of the\nbehavior occurs, the average avalanche shape becomes increasingly asymmetric,\nand individual avalanches exhibit motion in the direction perpendicular to\ntheir own density gradient."
    },
    {
        "anchor": "Hall viscosity, topological states and effective theories: Hall viscosity is a dissipationless transport coefficient whose value is\nquantized in units of the density in some topological phases and may be used as\na measure of topological order. I give an overview of the Hall viscosity, its\nrelation to Hall conductivity in Galilean invariant theories and its\nrealization in effective theories.",
        "positive": "High Photoresponsivity and Short Photo Response Times in Few-Layered\n  WSe$_2$ Transistors: Here, we report the photoconducting response of field-effect transistors\nbased on three atomic layers of chemical vapor transport grown WSe$_2$ crystals\nmechanically exfoliated onto SiO$_2$. We find that tri-layered WSe$_2$\nfield-effect transistors, built with the simplest possible architecture, can\ndisplay high hole mobilities ranging from 350 cm$^2$/Vs at room temperature\n(saturating at a value of ~500 cm$^2$/Vs below 50 K) displaying a strong\nphotocurrent response which leads to exceptionally high photo responsivities up\nto 7 A/W under white light illumination of the entire channel for power\ndensities p < 10$^2$ W/m$^2$. Under a fixed wavelength of $\\lambda$ = 532 nm\nand a laser spot size smaller than the conducting channel area we extract photo\nresponsitivities approaching 100 mA/W with concomitantly high external quantum\nefficiencies up to ~ 40 % at room temperature. These values surpass values\nrecently reported from more complex architectures, such as graphene and\ntransition metal dichalcogenides based heterostructures. Also, tri-layered\nWSe$_2$ photo-transistors display photo response times in the order of 10\nmicroseconds. Our results indicate that the addition of a few atomic layers\nconsiderably decreases the photo response times, probably by minimizing the\ninteraction with the substrates, while maintaining a very high\nphoto-responsivity."
    },
    {
        "anchor": "Non-equilibrium scalar field dynamics starting from Fock states: Absence\n  of thermalization in one dimensional phonons coupled to fermions: We propose a new method to study non-equilibrium dynamics of scalar fields\nstarting from non-Gaussian initial conditions using Keldysh field theory. We\nuse it to study dynamics of phonons coupled to non-interacting bosonic and\nfermionic baths, starting from initial Fock states. We find that in one\ndimension long wavelength phonons coupled to fermionic baths do not thermalize\nboth at low and high bath-temperatures. At low temperature, constraints from\nenergy-momentum conservation lead to a narrow bandwidth of particle-hole\nexcitations and the phonons effectively do not see this bath. On the other\nhand, the strong band-edge divergence of the particle-hole density of states\nleads to an undamped polariton-like mode of the dressed phonons above the band\nedge of the particle-hole excitations. These undamped modes contribute to the\nlack of thermalization of long wavelength phonons at high temperatures. In\nhigher dimensions, these constraints and the divergence of density of states\nare weakened and lead to thermalization at all wavelengths.",
        "positive": "Long-living dark coherence brought to light by magnetic-field controlled\n  photon echo: Larmor precession of the quasiparticle spin about a transverse magnetic field\nleads to the oscillations in the spontaneous photon echo signal due to the\nshuffling of the optical coherence between optically accessible (bright) and\ninaccessible (dark) states. Here we report on a new non-oscillating photon echo\nregime observed in the presence of non-equal dephasing rates of bright and dark\nstates. This regime enables the observation of the long-living dark optical\ncoherence. As a simple mechanical analogy, we suggest a charged particle moving\nin the magnetic field through the medium with anisotropic viscous friction. We\ndemonstrate the dark coherence retrieval in the spontaneous photon echo from\nexcitons in the InGaAs/GaAs quantum well."
    },
    {
        "anchor": "Current-induced microwave excitation of a domain wall confined in a\n  magnetic wire with bi-axial anisotropy: We studied the current-induced magnetization dynamics of a domain wall\nconfined in a magnetic wire with bi-axial anisotropy. We showed that above the\nthreshold current density, breathing-mode excitation, where the thickness of\nthe domain wall oscillates, is induced by spin-transfer torque. We found that\nthe breathing-mode can be applied as a source of microwave oscillation because\nthe resistance of the domain wall is a function of the domain wall thickness.\nIn a current sweep simulation, the frequency of the breathing-mode exhibits\nhysteresis because of the confinement.",
        "positive": "Multiband Tunable Large Area Hot Carrier Plasmonic-Crystal\n  Photodetectors: Optoelectronic functionalities of photodection and light harnessing rely on\nthe band-to-band excitation of semiconductors, thus the spectral response of\nthe devices is dictated and limited by their bandgap. A novel approach, free\nfrom this restriction, is to harvest the energetic electrons generated by the\nrelaxation of a plasmonic resonance in the vicinity of a metal-semiconductor\njunction. In this configuration, the optoelectronic and spectral response of\nthe detectors can be designed ad hoc just by tailoring the topology of metal\nstructures, which has tremendous applications in solar energy harvesting and\nphotodetection. Fully exploiting hot electron based optoelectronics yet\nrequires a platform that combines their exotic spectral capabilities with large\nscale manufacturing and high performance. Herein we report the first\nimplementation of a large area, low cost quasi 3D plasmonic crystal (PC) for\nhot electron photodetection, showcasing multiband selectivity in the VIS-NIR\nand unprecedented responsivity of 70 mA/W."
    },
    {
        "anchor": "Andreev Reflection in Ferromagnet/Superconductor/Ferromagnet Double\n  Junction Systems: We present a theory of Andreev reflection in a\nferromagnet/superconductor/ferromagnet double junction system. The spin\npolarized quasiparticles penetrate to the superconductor in the range of\npenetration depth from the interface by the Andreev reflection. When the\nthickness of the superconductor is comparable to or smaller than the\npenetration depth, the spin polarized quasiparticles pass through the\nsuperconductor and therefore the electric current depends on the relative\norientation of magnetizations of the ferromagnets. The dependences of the\nmagnetoresistance on the thickness of the superconductor, temperature, the\nexchange field of the ferromagnets and the height of the interfacial barriers\nare analyzed. Our theory explains recent experimental results well.",
        "positive": "Spins in few-electron quantum dots: This review describes the physics of spins in quantum dots containing one or\ntwo electrons, from an experimentalist's viewpoint. Various methods for\nextracting spin properties from experiment are presented, restricted\nexclusively to electrical measurements. Furthermore, experimental techniques\nare discussed that allow for: (1) the rotation of an electron spin into a\nsuperposition of up and down, (2) the measurement of the quantum state of an\nindividual spin and (3) the control of the interaction between two neighbouring\nspins by the Heisenberg exchange interaction. Finally, the physics of the\nrelevant relaxation and dephasing mechanisms is reviewed and experimental\nresults are compared with theories for spin-orbit and hyperfine interactions.\nAll these subjects are directly relevant for the fields of quantum information\nprocessing and spintronics with single spins (i.e. single-spintronics)."
    },
    {
        "anchor": "Interface States in Carbon Nanotube Junctions: Rolling up graphene: We study the origin of interface states in carbon nanotube intramolecular\njunctions between achiral tubes. By applying the Born-von Karman boundary\ncondition to an interface between armchair- and zigzag-terminated graphene\nlayers, we are able to explain their number and energies. We show that these\ninterface states, costumarily attributed to the presence of topological\ndefects, are actually related to zigzag edge states, as those of graphene\nzigzag nanoribbons. Spatial localization of interface states is seen to vary\ngreatly, and may extend appreciably into either side of the junction. Our\nresults give an alternative explanation to the unusual decay length measured\nfor interface states of semiconductor nanotube junctions, and could be further\ntested by local probe spectroscopies.",
        "positive": "Magnon Landau Levels and Spin Responses in Antiferromagnets: We study gauge fields produced by gradients of the Dzyaloshinskii-Moriya\ninteraction and propose a model of AFM topological insulator of magnons. In the\nlong wavelength limit, the Landau levels induced by the inhomogeneous\nDzyaloshinskii-Moriya interaction exhibit relativistic physics described by the\nKlein-Gordon equation. The spin Nernst response due to the formation of\nmagnonic Landau levels is compared to similar topological responses in skyrmion\nand vortex-antivortex crystal phases of AFM insulators. Our studies show that\nAFM insulators exhibit rich physics associated with topological magnon\nexcitations."
    },
    {
        "anchor": "Topological Defects and Gapless Modes in Insulators and Superconductors: We develop a unified framework to classify topological defects in insulators\nand superconductors described by spatially modulated Bloch and Bogoliubov de\nGennes Hamiltonians. We consider Hamiltonians H(k,r) that vary slowly with\nadiabatic parameters r surrounding the defect and belong to any of the ten\nsymmetry classes defined by time reversal symmetry and particle-hole symmetry.\nThe topological classes for such defects are identified, and explicit formulas\nfor the topological invariants are presented. We introduce a generalization of\nthe bulk-boundary correspondence that relates the topological classes to defect\nHamiltonians to the presence of protected gapless modes at the defect. Many\nexamples of line and point defects in three dimensional systems will be\ndiscussed. These can host one dimensional chiral Dirac fermions, helical Dirac\nfermions, chiral Majorana fermions and helical Majorana fermions, as well as\nzero dimensional chiral and Majorana zero modes. This approach can also be used\nto classify temporal pumping cycles, such as the Thouless charge pump, as well\nas a fermion parity pump, which is related to the Ising non-Abelian statistics\nof defects that support Majorana zero modes.",
        "positive": "Model study of the electron-phonon coupling in graphene; relative\n  importance of intraband and interband scattering: The aim of this model study of the electron-phonon coupling in graphene was\nto find out about the relative importance of the inter- and intraband\nscattering and which phonon modes are the most active. This was achieved by\nanalyzing the electron-phonon matrix element of the carbon dimer in the unit\ncell. We found that for the intra molecular orbital matrix elements the\nlongitudinal optical phonon mode is the active phonon mode. The matrix element\ncorresponding to sigma to sigma is greater than the matrix element for pi to pi\n. The inter molecular orbital scattering pi to sigma is driven by the\nout-of-plane acoustic phonon mode, while the out-of-plane optical mode does not\ncontribute for symmetry reasons. We found the unexpected result that the\nmagnitude of matrix element of the inter molecular orbital scattering pi to\nsigmat exceeds the intra molecular orbital scattering pi to pi . These results\nindicate that the in general not considered inter-band scattering has to be\ntaken into account when analyzing e.g. photo-hole lifetimes and the\nelectron-phonon coupling constant ?from photoemission data of graphene."
    },
    {
        "anchor": "Energy relaxation in hot electron quantum optics via acoustic and\n  optical phonon emission: We study theoretically the relaxation of hot quantum-Hall edge-channel\nelectrons under the emission of both acoustic and optical phonons. Aiming to\nmodel recent experiments with single-electron sources, we describe simulations\nthat provide the distribution of electron energies and arrival times at a\ndetector a fixed distance from the source. From these simulations we extract an\neffective rate of emission of optical phonons that contains contributions from\nboth a direct emission process as well as one involving inter-edge-channel\ntransitions that are driven by the sequential emission of first an acoustic --\nand then an optical -- phonon. Furthermore, we consider the mean energy loss\ndue to acoustic phonon emission and resultant broadening of the electron energy\ndistribution and derive an effective drift-diffusion model for this process.",
        "positive": "Hotter is easier: unexpected temperature dependence of spin qubit\n  frequencies: As spin-based quantum processors grow in size and complexity, maintaining\nhigh fidelities and minimizing crosstalk will be essential for the successful\nimplementation of quantum algorithms and error-correction protocols. In\nparticular, recent experiments have highlighted pernicious transient qubit\nfrequency shifts associated with microwave qubit driving. Workarounds for small\ndevices, including prepulsing with an off-resonant microwave burst to bring a\ndevice to a steady-state, wait times prior to measurement, and qubit-specific\ncalibrations all bode ill for device scalability. Here, we make substantial\nprogress in understanding and overcoming this effect. We report a surprising\nnon-monotonic relation between mixing chamber temperature and spin Larmor\nfrequency which is consistent with observed frequency shifts induced by\nmicrowave and baseband control signals. We find that purposefully operating the\ndevice at 200 mK greatly suppresses the adverse heating effect while not\ncompromising qubit coherence or single-qubit fidelity benchmarks. Furthermore,\nsystematic non-Markovian crosstalk is greatly reduced. Our results provide a\nstraightforward means of improving the quality of multi-spin control while\nsimplifying calibration procedures for future spin-based quantum processors."
    },
    {
        "anchor": "Sensing Coherent Phonons with Two-photon Interference: Detecting coherent phonons pose different challenges compared to coherent\nphotons due to the much stronger interaction between phonons and matter. This\nis especially true for high frequency heat carrying phonons, which are\nintrinsic lattice vibrations experiencing many decoherence events with the\nenvironment, and are thus generally assumed to be incoherent. Two photon\ninterference techniques, especially coherent population trapping (CPT) and\nelectromagnetically induced transparency (EIT), have led to extremely sensitive\ndetection, spectroscopy and metrology. Here, we propose the use of two photon\ninterference in a three level system to sense coherent phonons. Unlike prior\nworks which have treated phonon coupling as damping, we account for coherent\nphonon coupling using a full quantum-mechanical treatment. We observe strong\nasymmetry in absorption spectrum in CPT and negative dispersion in EIT\nsusceptibility in the presence of coherent phonon coupling which cannot be\naccounted for if only pure phonon damping is considered. Our proposal has\napplication in sensing heat carrying coherent phonons effects and understanding\ncoherent bosonic multi-pathway interference effects in three coupled oscillator\nsystems.",
        "positive": "Origin of temperature and field dependence of magnetic skyrmion size in\n  ultrathin nanodots: Understanding the physical properties of magnetic skyrmions is important for\nfundamental research with the aim to develop new spintronic device paradigms\nwhere both logic and memory can be integrated at the same level. Here, we show\na universal model based on the micromagnetic formalism that can be used to\nstudy skyrmion stability as a function of magnetic field and temperature. We\nconsider ultrathin, circular ferromagnetic magnetic dots. Our results show that\nmagnetic skyrmions with a small radius compared to the dot radius are always\nmetastable, while large radius skyrmions form a stable ground state. The change\nof energy profile determines the weak (strong) size dependence of the\nmetastable (stable) skyrmion as a function of temperature and/or field. These\nresults can open a path toward the design of optimal materials for skyrmion\nbased devices."
    },
    {
        "anchor": "Momentum-space structure of surface states in a topological semimetal\n  with a nexus point of Dirac lines: Three-dimensional topological semimetals come in different variants, either\ncontaining Weyl points or Dirac lines. Here we describe a more complicated\nmomentum-space topological defect where several separate Dirac lines connect\nwith each other, forming a momentum-space equivalent of the real-space nexus\nconsidered before for Helium-3. Close to the nexus the Dirac lines exhibit a\ntransition from type I to type II lines. We consider a general model of stacked\nhoneycomb lattices with the symmetry of Bernal (AB) stacked graphite and show\nthat the structural mirror symmetries in such systems protect the presence of\nthe Dirac lines, and also naturally lead to the formation of the nexus. By the\nbulk-boundary correspondence of topological media, the presence of Dirac lines\nlead to the formation of drumhead surface states at the side surfaces of the\nsystem. We calculate the surface state spectrum, and especially illustrate the\neffect of the nexus on these states.",
        "positive": "Signatures of Lifshitz transition in the optical conductivity of\n  two-dimensional tilted Dirac materials: Lifshitz transition is a kind of topological phase transition in which the\nFermi surface is reconstructed. It can occur in the two-dimensional (2D) tilted\nDirac materials when the energy bands change between the type-I phase ($0<t<1$)\nand the type-II phase ($t>1$) through the type-III phase ($t=1$), where\ndifferent tilts are parametrized by the values of $t$. In order to characterize\nthe Lifshitz transition therein, we theoretically investigate the longitudinal\noptical conductivities (LOCs) in type-I, type-II, and type-III Dirac materials\nwithin linear response theory. In the undoped case, the LOCs are constants\neither independent of the tilt parameter in both type-I and type-III phases or\ndetermined by the tilt parameter in the type-II phase. In the doped case, the\nLOCs are anisotropic and possess two critical frequencies determined by\n$\\omega=\\omega_1(t)$ and $\\omega=\\omega_2(t)$, which are also confirmed by the\njoint density of state. The tilt parameter and chemical potential can be\nextracted from optical experiments by measuring the positions of these two\ncritical boundaries and their separation\n$\\Delta\\omega(t)=\\omega_2(t)-\\omega_1(t)$. With increasing the tilting, the\nseparation becomes larger in the type-I phase whereas smaller in the type-II\nphase. The LOCs in the regime of large photon energy are exactly the same as\nthat in the undoped case. The type of 2D tilted Dirac bands can be determined\nby the asymptotic background values, critical boundaries and their separation\nin the LOCs. These can therefore be taken as signatures of Lifshitz transition\ntherein. The results of this work are expected to be qualitatively valid for a\nlarge number of 2D tilted Dirac materials, such as 8-\\emph{Pmmn} borophene\nmonolayer, $\\alpha$-SnS$_2$, TaCoTe$_2$, TaIrTe$_4$, and $1T^\\prime$ transition\nmetal dichalcogenides, due to the underlying intrinsic similarities of 2D\ntilted Dirac bands."
    },
    {
        "anchor": "Coherent radiation by magnets with exchange interactions: A wide class of materials acquires magnetic properties due to particle\ninteractions through exchange forces. These can be atoms and molecules\ncomposing the system itself, as in the case of numerous magnetic substances. Or\nthese could be different defects, as in the case of graphene, graphite, carbon\nnanotubes, and related materials. The theory is suggested describing fast\nmagnetization reversal in magnetic systems, whose magnetism is caused by\nexchange interactions. The effect is based on the coupling of a magnetic sample\nwith an electric circuit producing a feedback magnetic field. This method can\nfind various applications in spintronics. The magnetization reversal can be\nself-organized, producing spin superradiance. A part of radiation is absorbed\nby a resonator magnetic coil. But an essential part of radiation can also be\nemitted through the coil sides.",
        "positive": "Symmetry-induced interference effects in metalloporphyrin wires: Organo-metallic molecular structures where a single metallic atom is embedded\nin the organic backbone are ideal systems to study the effect of strong\ncorrelations on their electronic structure. In this work we calculate the\nelectronic and transport properties of a series of metalloporphyrin molecules\nsandwiched by gold electrodes using a combination of density functional theory\nand scattering theory. The impact of strong correlations at the central\nmetallic atom is gauged by comparing our results obtained using conventional\nDFT and DFT+U approaches. The zero bias transport properties may or may not\nshow spin-filtering behavior, depending on the nature of the d state closest to\nthe Fermi energy. The type of d state depends on the metallic atom and gives\nrise to interference effects that produce different Fano features. The\ninclusion of the U term opens a gap between the d states and changes\nqualitatively the conductance and spin-filtering behavior in some of the\nmolecules. We explain the origin of the quantum interference effects found as\ndue to the symmetry-dependent coupling between the d states and other molecular\norbitals and propose the use of these systems as nanoscale chemical sensors. We\nalso demonstrate that an adequate treatment of strong correlations is really\nnecessary to correctly describe the transport properties of metalloporphyrins\nand similar molecular magnets."
    },
    {
        "anchor": "Broad Band Optical Properties of Large Area Monolayer CVD Molybdenum\n  Disulfide: Recently emerging large-area single-layer MoS2 grown by chemical vapor\ndeposition has triggered great interest due to its exciting potential for\napplications in advanced electronic and optoelectronic devices. Unlike gapless\ngraphene, MoS2 has an intrinsic band gap in the visible which crosses over from\nan indirect to a direct gap when reduced to a single atomic layer. In this\narticle, we report a comprehensive study of fundamental optical properties of\nMoS2 revealed by optical spectroscopy of Raman, photoluminescence, and vacuum\nultraviolet spectroscopic ellipsometry. A band gap of 1.42 eV is determined by\nthe absorption threshold of bulk MoS2 that shifts to 1.83 eV in monolayer MoS2.\nWe extracted the high precision dielectric function up to 9.0 eV which leads to\nthe identification of many unique interband transitions at high symmetry points\nin the MoS2 momentum space. The positions of the A and B excitons in single\nlayers are found to shift upwards in energy compared with those of the bulk\nform and have smaller separation. A very strong optical critical point\npredicted to correspond to a quasi-particle gap is observed at 2.86 eV, which\nis attributed to optical transitions along the parallel bands between the M and\ngama points in the reduced Brillouin zone. The absence of the bulk MoS2\nspin-orbit interaction peak at ~ 3.0 eV in monolayer MoS2 is, as predicted, the\nconsequence of the coalescence of nearby excitons. A higher energy optical\ntransition at 3.98 eV, commonly occurred in bulk semiconductors, is associated\nwith a combination of several critical points.These optical transitions herein\nreported enhance our understanding of monolayer MoS2 as well as of\ntwo-dimensional systems in general, and thus provide informative guidelines for\nMoS2 optical device designs and theoretical considerations.",
        "positive": "Anomalous near-field heat transfer in carbon-based nano-structures with\n  edge states: We find an unusually optimal near field heat transfer, where the maximum heat\ntransfer is reached at experimentally feasible gap separation. We attribute\nthis to the localized zero-energy electronic edge states, which also\nsubstantially changes the near-field behaviors. We demonstrate these anomalous\nbehaviors in two typical carbon-based nano-structures: zigzag single-walled\ncarbon nanotubes and graphene nano-triangles. For the system of carbon\nnanotubes, the maximal heat flux in this work surpasses all the previous\nresults reported so far by several orders of magnitude. The underlying\nmechanisms for the peculiar effects are uncovered from a simple\nSu-Schrieffer-Heeger model. Our findings also offer a novel route to active\nnear-field thermal switch, where the heat flux can be modulated through tuning\nthe presence or absence of edge states."
    },
    {
        "anchor": "Unified description of saturation and bistability of intersubband\n  transitions in the weak and strong light-matter coupling regimes: We propose a unified description of intersubband absorption saturation for\nquantum wells inserted in a resonator, both in the weak and strong light-matter\ncoupling regimes. We demonstrate how absorption saturation can be engineered.\nIn particular we show that the saturation intensity increases linearly with the\ndoping in the strong coupling regime, while it remains doping independent in\nweak coupling. Hence, countering intuition, the most suitable region to exploit\nlow saturation intensities is not the ultra-strong coupling regime, but is\ninstead at the onset of the strong light-matter coupling. We further derive\nexplicit conditions for the emergence of bistability. This work sets the path\ntowards yet unexisting ultrafast mid-infrared semiconductor saturable\nabsorption mirrors (SESAMs) and bistable systems. As an example, we show how to\ndesign a mid-infrared SESAM with a three orders of magnitude reduction in\nsaturation intensity, down to about 5 kW/cm2.",
        "positive": "Collinear Orbital Antiferromagnetic Order and Magnetoelectricity in\n  Quasi-2D Itinerant-Electron Paramagnets, Ferromagnets and Antiferromagnets: We develop a comprehensive theory for magnetoelectricity in magnetically\nordered quasi-2D systems whereby in thermal equilibrium an electric field can\ninduce a magnetization $m$ and a magnetic field can induce a polarization. This\neffect requires that both space-inversion and time-reversal symmetry are\nbroken. Antiferromagnetic (AFM) order plays a central role in this theory. We\ndefine a N\\'eel operator $\\tau$ such that a nonzero expectation value $\\langle\n\\tau \\rangle$ signals AFM order, in the same way $m$ signals ferromagnetic (FM)\norder. While $m$ is even under space inversion and odd under time reversal,\n$\\tau$ describes a toroidal moment that is odd under both symmetries. Thus $m$\nand $\\langle \\tau \\rangle$ quantify complementary aspects of magnetic order in\nsolids. In quasi-2D systems FM order can be attributed to dipolar equilibrium\ncurrents that give rise to $m$. In the same way, AFM order arises from\nquadrupolar currents that generate the moment $\\langle \\tau \\rangle$. The\nelectric-field-induced magnetization can then be attributed to the electric\nmanipulation of the quadrupolar currents. We develop a $k \\cdot p$\nenvelope-function theory for AFM diamond structures that allows us to derive\nexplicit expressions for the operator $\\tau$. Considering FM zincblende and AFM\ndiamond, we derive quantitative expressions for the magnetoelectric responses\ndue to electric and magnetic fields that reveal explicitly the inherent duality\nof these responses required by thermodynamics. Magnetoelectricity is found to\nbe small in realistic calculations for quasi-2D electron systems. The\nmagnetoelectric response of quasi-2D hole systems turns out to be sizable,\nhowever, with moderate electric fields being able to induce a magnetic moment\nof one Bohr magneton per charge carrier. Our theory provides a broad framework\nfor the manipulation of magnetic order by means of external fields."
    },
    {
        "anchor": "Energetics of complex phase diagram in a tunable bilayer graphene probed\n  by quantum capacitance: Bilayer graphene provides a unique platform to explore the rich physics in\nquantum Hall effect. The unusual combination of spin, valley and orbital\ndegeneracy leads to interesting symmetry broken states with electric and\nmagnetic field. Conventional transport measurements like resistance\nmeasurements have been performed to probe the different ordered states in\nbilayer graphene. However, not much work has been done to directly map the\nenergetics of those states in bilayer graphene. Here, we have carried out the\nmagneto capacitance measurements with electric and magnetic field in a\nhexagonal boron nitride encapsulated dual gated bilayer graphene device. At\nzero magnetic field, using the quantum capacitance technique we measure the gap\naround the charge neutrality point as a function of perpendicular electric\nfield and the obtained value of the gap matches well with the theory. In\npresence of perpendicular magnetic field, we observe Landau level crossing in\nour magneto-capacitance measurements with electric field. The gap closing and\nreopening of the lowest Landau level with electric and magnetic field shows the\ntransition from one ordered state to another one. Further more we observe the\ncollapsing of the Landau levels near the band edge at higher electric field\n($\\bar D > 0.5$ V/nm), which was predicted theoretically. The complete\nenergetics of the Landau levels of bilayer graphene with electric and magnetic\nfield in our experiment paves the way to unravel the nature of ground states of\nthe system.",
        "positive": "Electronic Thermal Conductivity Measurements in Intrinsic Graphene: The electronic thermal conductivity of graphene and 2D Dirac materials is of\nfundamental interest and can play an important role in the performance of\nnano-scale devices. We report the electronic thermal conductivity, $K_{e}$, in\nsuspended graphene in the nearly intrinsic regime over a temperature range of\n20 to 300 K. We present a method to extract $K_{e}$ using two-point DC electron\ntransport at low bias voltages, where the electron and lattice temperatures are\ndecoupled. We find $K_e$ ranging from 0.5 to 11 W/m.K over the studied\ntemperature range. The data are consistent with a model in which heat is\ncarried by quasiparticles with the same mean free-path and velocity as\ngraphene's charge carriers."
    },
    {
        "anchor": "Weak (anti)localization in tubular semiconductor nanowires with\n  spin-orbit coupling: We compute analytically the weak (anti)localization correction to the Drude\nconductivity for electrons in tubular semiconductor systems of zinc blende\ntype. We include linear Rashba and Dresselhaus spin-orbit coupling (SOC) and\ncompare wires of standard growth directions $\\langle100\\rangle$,\n$\\langle111\\rangle$, and $\\langle110\\rangle$. The motion on the\nquasi-two-dimensional surface is considered diffusive in both directions:\ntransversal as well as along the cylinder axis. It is shown that Dresselhaus\nand Rashba SOC similarly affect the spin relaxation rates. For the\n$\\langle110\\rangle$ growth direction, the long-lived spin states are of helical\nnature. We detect a crossover from weak localization to weak anti-localization\ndepending on spin-orbit coupling strength as well as dephasing and scattering\nrate. The theory is fitted to experimental data of an undoped\n$\\langle111\\rangle$ InAs nanowire device which exhibits a top-gate-controlled\ncrossover from positive to negative magnetoconductivity. Thereby, we extract\ntransport parameters where we quantify the distinct types of SOC individually.",
        "positive": "Interaction induced topological protection in one-dimensional conductors: We discuss two one-dimensional model systems -- the first is a single channel\nquantum wire with Ising anisotropy, while the second is two coupled helical\nedge states. We show that the two models are governed by the same low energy\neffective field theory, and interactions drive both systems to exhibit phases\nwhich are metallic, but with all single particle excitations gapped. We show\nthat such states may be either topological or trivial; in the former case, the\nsystem demonstrates gapless end states, and insensitivity to disorder."
    },
    {
        "anchor": "Gate-controlled suppression of light-driven proton transport through\n  graphene electrodes: Recent experiments demonstrated that proton transport through graphene\nelectrodes can be accelerated by over an order of magnitude with low intensity\nillumination. Here we show that this photo-effect can be suppressed for a\ntuneable fraction of the infrared spectrum by applying a voltage bias. Using\nphotocurrent measurements and Raman spectroscopy, we show that such fraction\ncan be selected by tuning the Fermi energy of electrons in graphene with a\nbias, a phenomenon controlled by Pauli blocking of photo-excited electrons.\nThese findings demonstrate a dependence between graphene's electronic and\nproton transport properties and provide fundamental insights into molecularly\nthin electrode-electrolyte interfaces and their interaction with light.",
        "positive": "Coherent phonon dynamics in spatially separated graphene mechanical\n  resonators: Vibrational modes in mechanical resonators provide a promising candidate to\ninterface and manipulate classical and quantum information. The observation of\ncoherent dynamics between distant mechanical resonators can be a key step\ntowards scalable phonon-based applications. Here we report tunable coherent\nphonon dynamics with an architecture comprising three graphene mechanical\nresonators coupled in series, where all resonators can be manipulated by\nelectrical signals on control gates. We demonstrate coherent Rabi oscillations\nbetween spatially separated resonators indirectly coupled via an intermediate\nresonator serving as a phonon cavity. The Rabi frequency fits well with the\nmicrowave burst power on the control gate. We also observe Ramsey interference,\nwhere the oscillation frequency corresponds to the indirect coupling strength\nbetween these resonators. Such coherent processes indicate that information\nencoded in vibrational modes can be transferred and stored between spatially\nseparated resonators, which can open the venue of on-demand phonon-based\ninformation processing."
    },
    {
        "anchor": "A modified interferometer to measure anyonic braiding statistics: Existing quantum Hall interferometers measure twice the braiding phase,\n$e^{i2\\theta}$, of Abelian anyons, i.e. the phase accrued when one\nquasi-particle encircles another clockwise. We propose a modified\nFabry-P\\'{e}rot or Mach-Zehnder interferometer that can measure $e^{i\\theta}$.",
        "positive": "Coherent State Path Integral for Bloch Particle: We construct a coherent state path integral formalism for the one-dimensional\nBloch particle within the single band model. The transition amplitude between\ntwo coherent states is a sum of transition amplitudes with different winding\nnumbers on the two-dimensional phase space which has the same topology as that\nof the cylinder. Appearance of the winding number is due to the periodicity of\nthe quasi-momentum of the Bloch particle. Our formalism is successfully applied\nto a semiclassical motion of the Bloch particle under a uniform electric field.\nThe wave packet exhibits not only the Bloch oscillation but also a similar\nbreathing to the one for the squeezed state of a harmonic oscillator."
    },
    {
        "anchor": "Long-lived Topological Flatband Excitons in Semiconductor Moir\u00e9\n  Heterostructures: a Bosonic Kane-Mele Model Platform: Moir\\'e superlattices based on two-dimensional transition metal\ndichalcogenides (TMDs) have emerged as a highly versatile and fruitful platform\nfor exploring correlated topological electronic phases. One of the most\nremarkable examples is the recently discovered fractional quantum anomalous\nHall effect (FQAHE) under zero magnetic field. Here we propose a minimal\nstructure that hosts long-lived excitons -- a ubiquitous bosonic excitation in\nTMD semiconductors -- with narrow topological bosonic bands. The nontrivial\nexciton topology originates from hybridization of moir\\'e interlayer excitons,\nand is tunable by controlling twist angle and electric field. At small twist\nangle, the lowest exciton bands are isolated from higher energy bands, and\nprovides a solid-state realization of bosonic Kane-Mele model with topological\nflatbands, which could potentially support the bosonic version of FQAHE.",
        "positive": "Current distribution in a slit connecting two graphene half-planes: We investigate the joint effect of viscous and Ohmic dissipation on electric\ncurrent flow through a slit in a barrier dividing a graphene sheet in two. In\nthe case of the no-slip boundary condition, we find that the competition\nbetween the viscous and Ohmic types of the charge flow results in the evolution\nof the current density profile from a concave to convex shape. We provide a\ndetailed analysis of the evolution and identify favorable conditions to observe\nit in experiment. In contrast, in the case of the no-stress boundary condition,\nthere is no qualitative difference between the current profiles in the Ohmic\nand viscous limits. The dichotomy between the behavior corresponding to\ndistinct boundary conditions could be tested experimentally."
    },
    {
        "anchor": "Plasma solitons in gated two-dimensional electron systems: exactly\n  solvable analytical model for the regime beyond weak non-linearity: We analytically study plasma solitary waves, or solitons, in a\ntwo-dimensional (2D) electron system (ES) placed in close proximity to and\nbetween two ideal metallic gates. As a rule, solitons are described using a\nperturbative approach applicable only in the weak non-linearity regime. In\ncontrast, we analyze solitons considering a non-perturbative model. This\nframework enables an exact analytical description of the soliton shape.\nMoreover, it can be achieved in the regime beyond weak non-linearity -- when\nthe concentration deviation due to the soliton is of the order of the\nequilibrium concentration. We determine the conditions required for a soliton\nto exist and derive the relationship between its amplitude, width, and\nvelocity. We believe that our results obtained for the given model can provide\nvaluable insight into the physics of non-linear waves.",
        "positive": "Fundamental Limits to the Coupling between Light and 2D Polaritons by\n  Small Scatterers: Polaritonic modes in two-dimensional van der Waals materials display short\nin-plane wavelengths compared with light in free space. As interesting as this\nmay look from both fundamental and applied viewpoints, such large confinement\nis accompanied by poor in/out optical coupling, which severely limits the\napplication of polaritons in practical devices. Here, we quantify the coupling\nstrength between light and 2D polaritons in both homogeneous and anisotropic\nfilms using accurate rigorous analytical methods. In particular, we obtain\nuniversal expressions for the cross sections associated with photon-polariton\ncoupling by point and line defects, as well as with polariton extinction and\nscattering processes. Additionally, we find closed-form constraints that limit\nthe maximum possible values of these cross sections. Specifically, the maximum\nphoton-to-plasmon conversion efficiency in graphene is $\\sim10^{-6}$ and\n$\\sim10^{-4}$ for point and line scatterers sitting at its surface,\nrespectively, when the plasmon and photon energies are comparable in magnitude.\nWe further show that Mie resonators placed at an optimum distance from the film\ncan boost light-to-polariton coupling to order unity. Our results bear\nfundamental interest for the development of 2D polaritonics and the design of\napplications based on these excitations."
    },
    {
        "anchor": "Transport and noise in resonant tunneling diode using self-consistent\n  Green function calculation: The fully self-consistent non-equilibrium Green functions (NEGFs) approach to\nthe quantum transport is developed for the investigation of one-dimensional\nnano-scale devices. Numerical calculations performed for resonant tunneling\ndiodes (RTDs) of different designs and at different temperatures show\nreasonable results for the potential and electron density profiles, as well as\nfor the transmission coeffcient and the current-voltage characteristics. The\nresonant behavior is discussed in detail with respect to the quantum-well\nwidth, the barrier thickness, and the temperature. It is also shown that within\nthe framework of approach used the current noise spectral density can be\nstraightforwardly calculated for both the coherent and the sequential tunneling\nmodels. In qualitative agreement with experiments, obtained results highlight\nthe role of charge interaction which causes a fluctuation of density of states\nin the well and therefore a noise enhancement in the negative differential\nconductance region.",
        "positive": "Overview: Energy Absorption by Driven Mesoscopic Systems: There are three regimes in the theory of energy absorption: The adiabatic\nregime, the linear-response (Kubo) regime, and the non-perturbative regime. The\nmesoscopic Drude formula for electrical conductance, and the wall formula for\nfriction, can be regarded as special cases of the general formulation of the\ndissipation problem. The overview is based on a research report for 1998-2000."
    },
    {
        "anchor": "Ultrafast laser pulses to detect and generate fast thermo-mechanical\n  transients in matter: The use of femtosecond laser pulses to impulsively excite thermal and\nmechanical transients in matter has led, in the last years, to the development\nof picosecond acoustics. Recently, the pump-probe approach has been applied to\nnano-engineered materials to optically generate and detect acoustic waves in\nthe GHz-THz frequency range. In this paper, we review the latest advances on\nultrafast generation and detection of thermal gradients and pseudo-surface\nacoustic waves in two-dimensional lattices of metallic nanostructures.\nComparing the experimental findings to the numeric analysis of the full\nthermo-mechanical problem, these materials emerge as model systems to\ninvestigate both the mechanical and thermal energy transfer at the nanoscale.\nThe sensitivity of the technique to the nanostructures mass and shape\nvariations, coupled to the phononic crystal properties of the lattices opens\nthe way to a variety of applications ranging from hypersonic waveguiding to\nmass sensors with femtosecond time-resolution.ens the way to a variety of\napplications ranging from hypersonic waveguiding to mass sensors with\nfemtosecond time-resolution.",
        "positive": "Localization of the Helical Edge States in the Absense of External\n  Magnetic Field: Theoretically, the helical edge states of two-dimensional topological\ninsulators are protected from coherent backscattering due to nonmagnetic\ndisorder provided electron interactions are not too strong. Experimentally, the\nedges typically do not demonstrate the systematic and robust quantization, at\nthe same time little is known about the sub-Kelvin temperature behavior. Here,\nwe report the surprising localization of the edge states in an 8 nm HgTe\nquantum well in zero magnetic field at millikelvin temperatures. Additionally,\nthe magnetoresistance data at 0.5 K for the edges few micrometers long suggests\nthe field-dependent localization length $l_B\\propto B^{-\\alpha}$, with $\\alpha$\nranging approximately from $1.6$ to $2.8$ at fields $B\\lesssim0.1\\,\\text{T}$\nand $\\alpha\\approx1.1$ at higher fields up to $0.5\\,\\text{T}$. In the frame of\ndisordered interacting edge, these values of $\\alpha$ correspond to the\nLuttinger liquid parameters $K\\approx 0.9-1.1$ and $K\\approx 0.6$,\nrespectively. We discuss possible scenarios which could result in the zero\nmagnetic field localization."
    },
    {
        "anchor": "A Ballistic Two-Dimensional Lateral Heterojunction Bipolar Transistor: We propose and investigate the intrinsically thinnest transistor concept: a\nmonolayer ballistic heterojunction bipolar transistor based on a lateral\nheterostructure of transition metal dichalcogenides. The device is\nintrinsically thinner than a Field Effect Transistor because it does not need a\ntop or bottom gate, since transport is controlled by the electrochemical\npotential of the base electrode. As typical of bipolar transistors, the\ncollector current undergoes a tenfold increase for each 60 mV increase of the\nbase voltage over several orders of magnitude at room temperature, without\nsophisticated optimization of the electrostatics. We present a detailed\ninvestigation based on self-consistent simulations of electrostatics and\nquantum transport for both electron and holes of a pnp device using MoS$_2$ for\nthe 10-nm base and WSe$_2$ for emitter and collector. Our three-terminal device\nsimulations confirm the working principle and a large current modulation\nI$_\\text{ON}$/I$_\\text{OFF}\\sim 10^8$ for $\\Delta V_{\\rm EB}=0.5$ V. Assuming\nballistic transport, we are able to achieve a current gain $\\beta\\sim$ 10$^4$\nover several orders of magnitude of collector current and a cutoff frequency up\nto the THz range. Exploration of the rich world of bipolar nanoscale device\nconcepts in 2D materials is promising for their potential applications in\nelectronics and optoelectronics.",
        "positive": "Decoherence in current induced forces: Application to adiabatic quantum\n  motors: Current induced forces are not only related with the discrete nature of\nelectrons but also with its quantum character. It is natural then to wonder\nabout the effect of decoherence. Here, we develop the theory of current induced\nforces including dephasing processes and we apply it to study adiabatic quantum\nmotors (AQMs). The theory is based on B\\\"uttiker's fictitious probe model which\nhere is reformulated for this particular case. We prove that it accomplishes\nfluctuation-dissipation theorem. We also show that, in spite of decoherence,\nthe total work performed by the current induced forces remains equal to the\npumped charge per cycle times the voltage. We find that decoherence affects not\nonly the current induced forces of the system but also its intrinsic friction\nand noise, modifying in a non trivial way the efficiency of AQMs. We apply the\ntheory to study an AQM inspired by a classical peristaltic pump where we\nsurprisingly find that decoherence can play a crucial role by triggering its\noperation. Our results can help to understand how environmentally induced\ndephasing affects the quantum behavior of nano-mechanical devices."
    },
    {
        "anchor": "Anderson-type model for a molecule adsorbed on a metal surface: We investigate a modified Anderson model to study the local density of states\n(LDOS) of a molecular wire adsorbed on a metal. Using a self-consistent\nmean-field type approach we find an exponential decay of the LDOS along the\nmolecule. A repulsive on-site interaction on the molecule suppresses the\ntunneling and decreases the characteristic decay length.",
        "positive": "Effective out-of-plane g-factor in strained-Ge/SiGe quantum dots: Recently, lithographic quantum dots in strained-Ge/SiGe have become a\npromising candidate for quantum computation, with a remarkably quick\nprogression from demonstration of a quantum dot to qubit logic demonstrations.\nHere we present a measurement of the out-of-plane $g$-factor for single-hole\nquantum dots in this material. As this is a single-hole measurement, this is\nthe first experimental result that avoids the strong orbital effects present in\nthe out-of-plane configuration. In addition to verifying the expected\n$g$-factor anisotropy between in-plane and out-of-plane magnetic ($B$)-fields,\nvariations in the $g$-factor dependent on the occupation of the quantum dot are\nobserved. These results are in good agreement with calculations of the\n$g$-factor using the heavy- and light-hole spaces of the Luttinger Hamiltonian,\nespecially the first two holes, showing a strong spin-orbit coupling and\nsuggesting dramatic $g$-factor tunability through both the $B$-field and the\ncharge state."
    },
    {
        "anchor": "Effect of Magnetic Field on Goos-H\u00e4nchen Shifts in Gaped Graphene\n  Triangular Barrier: We study the effect of a magnetic field on Goos-H\\\"anchen shifts in gaped\ngraphene subjected to a double triangular barrier. Solving the wave equation\nseparately in each region composing our system and using the required boundary\nconditions, we then compute explicitly the transmission probability for\nscattered fermions. These wavefunctions are then used to derive the\nGoos-H\\\"anchen shifts in terms of different physical parameters such as energy,\nelectrostatic potential strength and magnetic field. Our numerical results show\nthat the Goos-H\\\"anchen shifts are affected by the presence of the magnetic\nfield and depend on the geometrical structure of the triangular barrier.",
        "positive": "Probing the concept of line tension down to the nanoscale: A novel mechanical approach is developed to explore by means of atom-scale\nsimulation the concept of line tension at a solid-liquid-vapor contact line as\nwell as its dependence on temperature, confinement, and solid/fluid\ninteractions. More precisely, by estimating the stresses exerted along and\nnormal to a straight contact line formed within a partially wet pore, the line\ntension can be estimated while avoiding the pitfalls inherent to the\ngeometrical scaling methodology based on hemispherical drops. The line tension\nfor Lennard-Jones fluids is found to follow a generic behavior with temperature\nand chemical potential effects that are all included in a simple contact angle\nparameterization. Former discrepancies between theoretical modeling and\nmolecular simulation are resolved, and the line tension concept is shown to be\nrobust down to molecular confinements. The same qualitative behavior is\nobserved for water but the line tension at the wetting transition diverges or\nconverges towards a finite value depending on the range of the solid/fluid\ninteractions at play."
    },
    {
        "anchor": "Describing transport in defected nanoparticle solids using a new,\n  hierarchical, simulation tool, TRIDENS: The efficiency of nanoparticle (NP) solar cells has grown impressively in\nrecent years, exceeding 16%. However, the carrier mobility in NP solar cells,\nand in other optoelectronic applications remains low, thus critically limiting\ntheir performance. Therefore, carrier transport in NP solids needs to be better\nunderstood to further improve the overall efficiency of NP solar cell\ntechnology. However, it is technically challenging to simulate experimental\nscale samples, as physical processes from atomic to mesoscopic scales all\ncrucially impact transport. To rise to this challenge, here we report the\ndevelopment of TRIDENS: the Transport in Defected Nanoparticle Solids\nSimulator, that adds three more hierarchical layers to our previously developed\nHINTS code for nanoparticle solar cells. In TRIDENS, we first introduced planar\ndefects, such as twin planes and grain boundaries into individual NP SLs that\ncomprised the order of 10^3 NPs. Then we used HINTS to simulate the transport\nacross tens of thousands of defected NP SLs, and constructed the distribution\nof the NP SL mobilities with planar defects. Second, the defected NP SLs were\nassembled into a resistor network with more than 10^4 NP SLs, thus representing\nabout 10^7 individual NPs. Finally, the TRIDENS results were analyzed by finite\nsize scaling to explore whether the percolation transition, separating the\nphase where the low mobility defected NP SLs percolate, from the phase where\nthe high mobility undefected NP SLs percolate drives a\nlow-mobility-to-high-mobility transport crossover that can be extrapolated to\nmacroscopic length scales. For the theoretical description, we adapted the\nEfros-Shklovskii bimodal mobility distribution percolation model. We\ndemonstrated that the ES bimodal theory's two-variable scaling function is an\neffective tool to quantitatively characterize this\nlow-mobility-to-high-mobility transport crossover.",
        "positive": "Rectification in mesoscopic AC-gated semiconductor devices: We measure the rectified dc currents resulting when a 3-terminal\nsemiconductor device with gate-dependent conductance is driven with an ac gate\nvoltage. The rectified currents exhibit surprisingly complex behaviour as the\ndc source-drain bias voltage, the dc gate voltage and the amplitude of the ac\ngate voltage are varied. We obtain good agreement between our data and a model\nbased on simple assumptions about the stray impedances on the sample chip, over\na wide frequency range. This method is applicable to many types of experiment\nwhich involve ac gating of a non-linear device, and where an undesireable\nrectified contribution to the measured signal is present. Finally, we evaluate\nthe small rectified currents flowing in tunable-barrier electron pumps operated\nin the pinched-off regime. These currents are at most $10^{-12}$ of the pumped\ncurrent for a pump current of 100 pA. This result is encouraging for the\ndevelopment of tunable-barrier pumps as metrological current standards."
    },
    {
        "anchor": "Spectrum of Landau Levels in GaAs Quantum Wells: We have studied the optical and electrical spectra from an n i p LED as a\nfunction of magnetic field. This sample incorporated three GaAs quantum wells\nin the intrinsic region. This device had excess n type doping and as a result.\nThe quantum wells were populated by a two dimension Landau electron gas. The\nbroad B0 field emission band evolved into a series of discrete features in the\npresence of a magnetic field. These were identified as interband transitions\nbetween the different values of l. Landau levels associated with the sub-bands,\nwith the selection rule. An energy splitting between the two polarised\ncomponents was observed for each Landau level transition. This was found to be\nequal to the sum of the conduction and valence band spin splittings. We used\nthe know value of electron g factor to determine the valence band spin\nsplittings. Our experimental values were compared to the numerically calculated\nvalues and were found to be in reasonable agreement.",
        "positive": "Non-quantized square-root topological insulators: a realization in\n  photonic Aharonov-Bohm cages: Topological Insulators are a novel state of matter where spectral bands are\ncharacterized by quantized topological invariants. This unique quantized\nnon-local property commonly manifests through exotic bulk phenomena and\ncorresponding robust boundary effects. In our work, we report a new type of\ntopological insulator exhibiting spectral bands with non-quantized topological\nproperties, but with a quantization that arises in a corresponding system where\nthe square of the Hamiltonian is taken. We provide a thorough theoretical\nanalysis as well as an experimental demonstration based on photonic\nAharonov-Bohm cages to highlight the bulk and boundary properties of this\nneophyte state of matter."
    },
    {
        "anchor": "Probing photon energy statistics of an emitter using photon correlations: We investigate the possibility of measuring the homogeneous and inhomogeneous\ncontribution to the linewidth of a spectrally diffusing single photon emitter\nusing a simple photon correlation spectroscopy method (PCS). The photon energy\nstatistics of the homogeneous line (poissonian) and of the spectral diffusion\n(first order markovian) being of different natures, they act differently on the\nhalf-line autocorrelation function (HLAF). We model here their effects and show\nit is possible to extricate them, opening the opportunity to determine\nseparately the homogeneous linewidth, and the spectral diffusion amplitude.",
        "positive": "Self-consistent quantum-kinetic theory for interacting drifting\n  electrons and force-driven phonons in a 1D system: A self-consistent quantum-kinetic model is developed for studying\nstrong-field nonlinear electron transport interacting with force-driven phonons\nwithin a quantum-wire system. For this model, phonons can be dragged into\nmotion through strong electron-phonon scattering by fast-moving electrons along\nthe opposite direction of the DC electric field. Meanwhile, the DC-field\ninduced charge current of electrons can be either enhanced or reduced by the\nsame electron-phonon scattering, depending on the relative direction of a DC\nfield with respect to that of an applied temperature gradient for driving\nphonons. By making use of this quantum-kinetic model beyond the relaxation-time\napproximation, neither electron nor phonon temperature is required for\ndescribing ultrafast electron-phonon scattering and their correlated transports\nin this 1D electronic-lattice system. onsistent quantum-kinetic model is\ndeveloped for studying strong-field nonlinear electron transport interacting\nwith force-driven phonons within a quantum-wire system. For this model, phonons\ncan be dragged into motion through strong electron-phonon scattering by\nfast-moving electrons along the opposite direction of the DC electric field.\nMeanwhile, the DC-field induced charge current of electrons can be either\nenhanced or reduced by the same electron-phonon scattering, depending on the\nrelative direction of a DC field with respect to that of an applied temperature\ngradient for driving phonons. By making use of this quantum-kinetic model\nbeyond the relaxation-time approximation, neither electron nor phonon\ntemperature is required for describing ultrafast electron-phonon scattering and\ntheir correlated transports in this 1D electronic-lattice system."
    },
    {
        "anchor": "Designing Photonic Topological Insulators with Quantum-Spin-Hall Edge\n  States using Topology Optimization: Designing photonic topological insulators is highly non-trivial because it\nrequires inversion of band symmetries around the band gap, which was so far\ndone using intuition combined with meticulous trial and error. Here we take a\ncompletely different approach: we consider the design of photonic topological\ninsulators as an inverse design problem and use topology optimization to\nmaximize the transmission through an edge mode with a sharp bend. Two design\ndomains composed of two different, but initially identical,\nC$_\\text{6v}$-symmetric unit cells define the geometrical design problem.\nRemarkably, the optimization results in a photonic topological insulator\nreminiscent of the shrink-and-grow approach to quantum-spin-Hall photonic\ntopological insulators but with notable differences in the topology of the\ncrystal as well as qualitatively different band structures and with\nsignificantly improved performance as gauged by the band-gap sizes, which are\nat least 50 \\% larger than previous designs. Furthermore, we find a directional\nbeta factor exceeding 99 \\%, and very low losses for sharp bends. Our approach\nallows for the introduction of fabrication limitations by design and opens an\navenue towards designing PTIs with hitherto unexplored symmetry constraints.",
        "positive": "Two-electron bound states in continuum in quantum dots: Bound state in continuum (BIC) might appear in open quantum dots for\nvariation of the dot's shape. By means of the equations of motion of Green\nfunctions we investigate effect of strong intradot Coulomb interactions on that\nphenomenon in the framework of impurity Anderson model. Equation that imaginary\npart of poles of the Green function equals to zero gives condition for BICs. As\na result we show that Coulomb interactions replicate the single-electron BICs\ninto two-electron ones."
    },
    {
        "anchor": "Artificial Life in an Exciton-Polariton Lattice: We show theoretically that a lattice of exciton-polaritons can behave as a\nlife-like cellular automaton when simultaneously excited by a continuous wave\ncoherent field and a time-periodic sequence of non-resonant pulses. This\nprovides a mechanism of realizing a range of highly sought spatiotemporal\nstructures under the same conditions, including: discrete solitons, oscillating\nsolitons, rotating solitons, breathers, soliton trains, guns, and choatic\nbehaviour. These structures can survive in the system indefinitely, despite the\npresence of dissipation, and allow universal computation.",
        "positive": "Microscopic origin of the next generation fractional quantum Hall effect: Most of the fractions observed to date belong to the sequences $\\nu=n/(2pn\\pm\n1)$ and $\\nu=1-n/(2pn\\pm 1)$, $n$ and $p$ integers, understood as the familiar\n{\\em integral} quantum Hall effect of composite fermions. These sequences fail\nto accommodate, however, many fractions such as $\\nu=4/11$ and 5/13, discovered\nrecently in ultra-high mobility samples at very low temperatures. We show that\nthese \"next generation\" fractional quantum Hall states are accurately described\nas the {\\em fractional} quantum Hall effect of composite fermions."
    },
    {
        "anchor": "Room temperature magnetic order on zigzag edges of narrow graphene\n  nanoribbons: Magnetic order emerging in otherwise non-magnetic materials as carbon is a\nparadigmatic example of a novel type of s-p electron magnetism predicted to be\nof exceptional high-temperature stability. It has been demonstrated that atomic\nscale structural defects of graphene can host unpaired spins. However, it is\nstill unclear under which conditions long-range magnetic order can emerge from\nsuch defect-bound magnetic moments. Here we propose that in contrast to random\ndefect distributions, atomic scale engineering of graphene edges with specific\ncrystallographic orientation, comprising edge atoms only from one sub-lattice\nof the bipartite graphene lattice, can give rise to a robust magnetic order. We\nemploy a nanofabrication technique based on Scanning Tunneling Microscopy to\ndefine graphene nanoribbons with nanometer precision and well-defined\ncrystallographic edge orientations. While armchair ribbons display quantum\nconfinement gap, zigzag ribbons narrower than 7 nm reveal a bandgap of about\n0.2 - 0.3 eV, which can be identified as a signature of interaction induced\nspin ordering along their edges. Moreover, a semiconductor to metal transition\nis revealed upon increasing the ribbon width, indicating the switching of the\nmagnetic coupling between opposite ribbon edges from antiferromagnetic to\nferromagnetic configuration. We found that the magnetic order on graphene edges\nof controlled zigzag orientation can be stable even at room temperature,\nraising hope for graphene-based spintronic devices operating under ambient\nconditions.",
        "positive": "Spin Dynamics in Driven Composite Multiferroics: A spin dynamics approach has been used to study the behavior of the magnetic\nspins and the electric pseudo-spins in a 1-D composite multiferroic chain with\na linear magneto-electric coupling at the interface. The response is\ninvestigated with either external magnetic or electric fields driving the\nsystem. The spin dynamics is based on the Landau-Lifshitz-Gilbert equation. A\nGaussian white noise is later added into the dynamic process to include the\nthermal effects. The interface requires a closer inspection of the\nmagneto-electric effects. Thus, we construct a 2-D ladder model to describe the\nbehavior of the magnetic spins and the electric pseudo-spins with different\nmagneto-electric couplings."
    },
    {
        "anchor": "GHz photon-activated hopping between localized states in a silicon\n  quantum dot: We discuss the effects of gigahertz photon irradiation on a degenerately\nphosphorous-doped silicon quantum dot, in particular, the creation of voltage\noffsets on gate leads and the tunneling of one or two electrons via Coulomb\nblockade lifting at 4.2K. A semi-analytical model is derived that explains the\nmain features observed experimentally. Ultimately both effects may provide an\nefficient way to optically control and operate electrically isolated structures\nby microwave pulses. In quantum computing architectures, these results may lead\nto the use of microwave multiplexing to manipulate quantum states in a\nmulti-qubit configuration.",
        "positive": "Tunable plasmons in atomically thin gold nanodisks: The ability to modulate light at high speeds is of paramount importance for\ntelecommunications, information processing, and medical imaging technologies.\nThis has stimulated intense efforts to master optoelectronic switching at\nvisible and near-infrared frequencies, although coping with current computer\nspeeds in integrated architectures still remains a major challenge. As a\npartial success, midinfrared light modulation has been recently achieved\nthrough gating patterned graphene. Here we show that atomically thin noble\nmetal nanoislands can extend optical modulation to the visible and\nnear-infrared spectral range. We find plasmons in thin metal nanodisks to\nproduce similar absorption cross-sections as spherical particles of the same\ndiameter. Using realistic levels of electrical doping, plasmons are shifted by\nabout half their width, thus leading to a factor-of-two change in light\nabsorption. These results, which we substantiate on microscopic quantum theory\nof the optical response, hold great potential for the development of electrical\nvisible and near-infrared light modulation in integrable, nanoscale devices."
    },
    {
        "anchor": "Perturbation theory for an Anderson quantum dot asymmetrically attached\n  to two superconducting leads: Self-consistent perturbation expansion up to the second order in the\ninteraction strength is used to study a single-level quantum dot with local\nCoulomb repulsion attached asymmetrically to two generally different\nsuperconducting leads. At zero temperature and wide range of other parameters\nthe spin-symmetric version of the expansion yields excellent results for the\nposition of the $0-\\pi$ impurity quantum phase transition boundary and\nJosephson current together with the energy of Andreev bound states in the\n$0$-phase as confirmed by numerical calculations using the Numerical\nRenormalisation Group method. We analytically prove that the method is\ncharge-conserving as well as thermodynamically consistent. Explicit formulas\nfor the position of the $0-\\pi$ phase boundary are presented for the\nHartree-Fock approximation as well as for its variant called Generalized Atomic\nLimit. It is shown that the Generalized Atomic Limit can be used as a quick\nestimate for the position of the phase boundary at half-filling in a broad\nrange of parameters. We apply our second order perturbation method to the\ninterpretation of the existing experimental data on the phase boundary with\nvery satisfactory outcome suggesting that the so far employed heavy numerical\ntools such as Numerical Renormalization Group and/or Quantum Monte Carlo are\nnot necessary in a class of generic situations and can be safely replaced by a\nperturbative approach.",
        "positive": "Biskyrmions Lattices in Centrosymmetric Magnetic Films: Abstract Theoretical framework is developed that explains biskyrmion lattices\nobserved in non-chiral magnetic films. We study films of finite thickness\ncontaining up to $1000\\times1000\\times100$ spins. Hexatic biskyrmion lattices\nin a pure 2D exchange model are naturally described by the Weierstrass $\\wp$\nand $\\zeta$ elliptic functions. Starting with such a lattice as an initial\nstate we investigate how it evolves towards the minimum-energy state in the\npresence of perpendicular magnetic anisotropy and dipole-dipole interaction. In\naccordance with experiments, we find that the final state is a triangular\nlattice of biskyrmion bubbles containing Bloch lines."
    },
    {
        "anchor": "Quantum control of hole spin qubits in double quantum dots: Hole spin qubits in semiconductor quantum dots (QDs) are promising candidates\nfor quantum information processing due to their weak hyperfine coupling to\nnuclear spins, and to the strong spin-orbit coupling which allows for rapid\noperation time. We propose a coherent control on two heavy-hole spin qubits in\na double QD by a fast adiabatic driving protocol, which helps to achieve higher\nfidelities than other experimentally commonly used protocols as linear ramping,\n$\\pi$-pulses or Landau-Zener passages. Using fast quasiadiabatic driving via\nspin-orbit coupling, it is possible to reduce charge noise significantly for\nqubit manipulation and achieve high robustness for the qubit initialization. We\nalso implement one and two-qubit gates, in particular, NOT, CNOT, and SWAP-like\ngates, of hole spins in a double QD achieving fidelities above $99\\%$,\nexhibiting the capability of hole spins to implement universal gates for\nquantum computing.",
        "positive": "Anisotropic MagnetoMemristance: In the last decade, nanoscale resistive devices with memory have been the\nsubject of intense study because of their possible use in brain-inspired\ncomputing. However, operational endurance is one of the limiting factors in the\nadoption of such technology. For this reason, we discuss the emergence of\ncurrent-induced memristance in magnetic materials, known for their durability.\nWe show analytically and numerically that a single ferromagnetic layer can\npossess GHz memristance, due to a combination of two factors: a current-induced\ntransfer of angular momentum (Zhang-Li torque) and the anisotropic\nmagnetoresistance (AMR). We term the resulting effect the anisotropic\nmagneto-memristance (AMM). We connect the AMM to the topology of the\nmagnetization state, within a simple model of a 1-dimensional annulus-shaped\nmagnetic layer, confirming the analytical results with micromagnetic\nsimulations for permalloy. Our results open a new path towards the realization\nof single-layer magnetic memristive devices operating at GHz frequencies."
    },
    {
        "anchor": "Cross-correlation spin noise spectroscopy of heterogeneous interacting\n  spin systems: We develop and apply a minimally invasive approach for characterization of\ninter-species spin interactions by detecting spin fluctuations alone. We\nconsider a heterogeneous two-component spin ensemble in thermal equilibrium\nthat interacts via binary exchange coupling, and we determine\ncross-correlations between the intrinsic spin fluctuations exhibited by the two\nspecies. Our theoretical predictions are experimentally confirmed using\n`two-color' optical spin noise spectroscopy on a mixture of interacting Rb and\nCs alkali vapors. The results allow us to explore the rates of spin exchange\nand total spin relaxation under conditions of strict thermodynamic equilibrium.",
        "positive": "Nonlinear interactions of dipolar excitons and polaritons in MoS2\n  bilayers: Nonlinear interactions between excitons strongly coupled to light are key for\naccessing quantum many-body phenomena in polariton systems. Atomically-thin\ntwo-dimensional semiconductors provide an attractive platform for strong\nlight-matter coupling owing to many controllable excitonic degrees of freedom.\nAmong these, the recently emerged exciton hybridization opens access to\nunexplored excitonic species, with a promise of enhanced interactions. Here, we\nemploy hybridized interlayer excitons (hIX) in bilayer MoS2 to achieve highly\nnonlinear excitonic and polaritonic effects. Such interlayer excitons possess\nan out-of-plane electric dipole as well as an unusually large oscillator\nstrength allowing observation of dipolar polaritons(dipolaritons) in bilayers\nin optical microcavities. Compared to excitons and polaritons in MoS2\nmonolayers, both hIX and dipolaritons exhibit about 8 times higher\nnonlinearity, which is further strongly enhanced when hIX and intralayer\nexcitons, sharing the same valence band, are excited simultaneously. This gives\nrise to a highly nonlinear regime which we describe theoretically by\nintroducing a concept of hole crowding. The presented insight into many-body\ninteractions provides new tools for accessing few-polariton quantum\ncorrelations."
    },
    {
        "anchor": "Asymmetry in effective fields of spin-orbit torques in Pt/Co/Pt stacks: Measurements of switching via spin-orbit coupling (SOC) mechanisms are\ndiscussed for a pair of inverted Pt/Co/Pt stacks with asymmetrical Pt\nthicknesses. Taking into account the planar Hall effect contribution, effective\nfields of spin-orbit torques (SOT) are evaluated using lock-in measurements of\nthe first and second harmonics of the Hall voltage. Reversing the stack\nstructure leads to significant asymmetries in the switching behavior, including\nclear evidence of a nonlinear current dependence of the transverse effective\nfield. Our results demonstrate potentially complex interplay in devices with\nall-metallic interfaces utilizing SOT.",
        "positive": "Micromagnetic simulation of magnetic small-angle neutron scattering from\n  two-phase nanocomposites: The recent development of a micromagnetic simulation methodology - suitable\nfor multiphase magnetic nanocomposites - permits the computation of the\nmagnetic microstructure and of the associated magnetic small-angle neutron\nscattering (SANS) cross section of these materials. In this review article we\nsummarize results on the micromagnetic simulation of magnetic SANS from\ntwo-phase nanocomposites. The decisive advantage of this approach resides in\nthe possibility to srutinize the individual magnetization Fourier contributions\nto the total magnetic SANS cross section, rather than their sum, which is\ngenerally obtained from experiment. The procedure furnishes unique and\nfundamental information regarding magnetic neutron scattering from nanomagnets."
    },
    {
        "anchor": "Microwave-assisted transport via localized states in degenerately doped\n  Si single electron transistors: Resonant microwave-assisted and DC transport are investigated in degenerately\ndoped silicon single electron transistors. A model based on hopping via\nlocalized impurity states is developed and first used to explain both the DC\ntemperature dependence and the AC response. In particular, the non-monotonic\npower dependence of the resonant current under irradiation is proved to be\nconsistent with spatial Rabi oscillations between these localized states.",
        "positive": "The dark side of benzene: interference vs. interaction: We present the study of the linear conductance vs.\\ applied gate voltage for\nan interacting six site ring structure, which is threaded by a flux of $\\pi$\nand coupled to a left and a right lead. This ring structure is designed to have\na vanishing conductance for all gate voltages and temperatures provided\ninteractions are ignored. Therefore this system is an ideal testbed to study\nthe interplay of interaction and interference. First we find a Kondo type\nresonance for rather large hopping parameter. Second, we find additional\nresonance peaks which can be explained by a population blocking mechanism. To\nthis end we have to extend the Kubo approach within the Density Matrix\nRenormalization Group method to handle degenerate states."
    },
    {
        "anchor": "Two Anderson Impurity problem: Kondo-doublets beyond the Kondo Limit: We analyze the effects of high energy configurations on the Kondo-doublet\ninteraction between two Anderson impurities. We found that the Kondo doublet\nstates are robust and that their coherence energy is incremented by the\ninclusion of high energy configurations. Analytic expressions are obtained for\nthe corrections near the Kondo limit. Analysis of the system in the\nintermediate valence regime shows that the behavior of the system can be\nchanged from ferromagnetic to sligthy antiferromagnetic by tuning the system\nparameters; this regime can also be used to study the interplay between\nhole-driven and electron-driven coherence effects.",
        "positive": "Morphology and magneto-transport in exfoliated graphene on ultrathin\n  crystalline \\b{eta}-Si3N4(0001)/Si(111): We report the first experimental study of graphene transferred on\n\\b{eta}-Si3N4(0001)/Si(111). Our work provides a comprehensive quantitative\nunderstanding of the physics of ultrathin Si3N4 as a gate dielectric for\ngraphene-based devices. The Si3N4 film was grown on Si(111) under ultra-high\nvacuum (UHV) conditions and investigated by scanning tunneling microscopy\n(STM). Subsequently, a graphene flake was deposited on top of it by a\npolymer-based transfer technique, and a Hall bar device was fabricated from the\ngraphene flake. STM was employed again to study the graphene flake under UHV\nconditions after device fabrication and showed that surface quality is\npreserved. Electrical transport measurements, carried out at low temperature in\nmagnetic field, revealed back gate modulation of carrier type and density in\nthe graphene channel and showed the occurrence of weak localization. Under\nthese experimental conditions, no leakage current between back gate and\ngraphene channel was detected."
    },
    {
        "anchor": "The controllable pi - SQUID: We have fabricated and studied a new kind of DC SQUID in which the magnitude\nand sign of the critical current of the individual Josephson junctions can be\ncontrolled by additional voltage probes connected to the junctions. We show\nthat the amplitude of the voltage oscillations of the SQUID as a function of\nthe applied magnetic field can be tuned and that the phase of the oscillations\ncan be switched between 0 and $\\pi$ in the temperature range of 0.1 - 4.2 K\nusing a suitable control voltage. This is equivalent to the external\napplication of (n+1/2) flux quantum.",
        "positive": "All-optical Coherent Control of Electrical Currents in Single GaAs\n  Nanowires: A phase-stable superposition of femtosecond pulses and their second harmonic\ninduces ultrashort microampere current bursts in single unbiased GaAs\nnanowires. Current injection relies on quantum interference of one- and\ntwo-photon absorption pathways."
    },
    {
        "anchor": "Landau levels in wrinkled and rippled graphene sheets: We study the discrete energy spectrum of curved graphene sheets in the\npresence of a magnetic field. The shifting of the Landau levels is determined\nfor complex and realistic geometries of curved graphene sheets. The energy\nlevels follow a similar square root dependence on the energy quantum number as\nfor rippled and flat graphene sheets. The Landau levels are shifted towards\nlower energies proportionally to the average deformation and the effect is\nlarger compared to a simple uni-axially rippled geometry. Furthermore, the\nresistivity of wrinkled graphene sheets is calculated for different average\nspace curvatures and shown to obey a linear relation. The study is carried out\nwith a quantum lattice Boltzmann method, solving the Dirac equation on curved\nmanifolds.",
        "positive": "Topological Edge States Induced by Zak's Phase in A3B Monolayers: In crystalline systems, charge polarization is related to Zak's phase\ndetermined by bulk band topology. Nontrivial charge polarization induces robust\nedge states accompanied with fractional charge. In Su-Schrieffer-Heeger (SSH)\nmodel, it is known that the strong modulation of electron hopping causes\nnontrivial charge polarization even in the presence of inversion symmetry.\nHere, we consider a bi-atomic honeycomb lattice to introduce such strong\nmodulation, i.e. A$_3$B sheet. By tuning hopping ratio and onsite potential\ndifference between A and B atoms, we show that topological phase transition\ncharacterized by Zak's phase occurs. Furthermore, we propose that C$_3$N and\nBC$_3$ are the possible realistic materials on the basis of first-principles\ncalculations. Both of them display topological edge states induced by Zak's\nphase without spin-orbital couplings and external fields unlike conventional\ntopological insulators."
    },
    {
        "anchor": "Electronic control of edge-mode spectrum of integer-hall-effect 2d\n  electron waveguides: In this paper, the control of the edge-mode spectrum of integer-Hall-effect\n2D waveguides by electric field is proposed and modeled with the effective mass\napproach. Under certain found conditions, the applied transversal electric\nfield allows refining the modal spectrum from non-localized waves, and,\nadditionally, it can switch the edge-mode from the propagating to the\nevanescent state, and it is interesting in the design of the edge-mode off and\non logic components. These waveguides, arbitrary biased by potentials, are\ndescribed by the Pauli spin-less charge equation, and they are simulated using\nthe order reduction method of partial differential equations in its Kron s\nquantum-circuit representation. Additionally to the spectrum control mechanism,\nthe influence of large-scale disorder of confinement potential and magnetic\nfield on the edge localization and modal switching is studied",
        "positive": "Pseudodoping of Metallic Two-Dimensional Materials by The Supporting\n  Substrates: We demonstrate how hybridization between a two-dimensional material and its\nsubstrate can lead to an apparent heavy doping, using the example of monolayer\nTaS$_2$ grown on Au(111). Combining $\\textit{ab-initio}$ calculations, scanning\ntunneling spectroscopy experiments and a generic model, we show that strong\nchanges in Fermi areas can arise with much smaller actual charge transfer. This\nmechanism, which we refer to as pseudodoping, is a generic effect for metallic\ntwo-dimensional materials which are either adsorbed to metallic substrates or\nembedded in vertical heterostructures. It explains the apparent heavy doping of\nTaS$_2$ on Au(111) observed in photoemission spectroscopy and spectroscopic\nsignatures in scanning tunneling spectroscopy. Pseudodoping is associated with\nnon-linear energy-dependent shifts of electronic spectra, which our scanning\ntunneling spectroscopy experiments reveal for clean and defective TaS$_2$\nmonolayer on Au(111). The influence of pseudodoping on the formation of charge\nordered, magnetic, or superconducting states is analyzed."
    },
    {
        "anchor": "Tunable Electronic Properties of Multilayer Phosphorene and Its\n  Nanoribbons: We study the effects of a vertical electric field on the electronic band\nstructure and transport in multilayer phosphorene and its nanoribbons. In\nphosphorene, at a critical value of the vertical electric field ($E_c$), the\nband gap closes and the band structure undergoes a massive-to-massless Dirac\nfermion transition along the armchair direction. This transition is observable\nin quantum Hall measurements, as the power-law dependence of the Landau-level\nenergy on the magnetic field $B$ goes from $\\sim (n+1/2)B$ below $E_c$, to\n$\\sim [(n+1/2)B]^{2/3}$ at $E_c$, to $\\sim [(n+1/2)B]^{1/2}$ above $E_c$. In\nmultilayer phosphorene nanoribbons (PNRs), the vertical electric field can be\nemployed to manipulate the midgap energy bands that are associated with edge\nstates, thereby giving rise to new device functionalities. We propose a\ndual-edge-gate PNR structure that works as a quantum switch.",
        "positive": "Finite Size Scaling Analysis of the Anderson Transition: This chapter describes the progress made during the past three decades in the\nfinite size scaling analysis of the critical phenomena of the Anderson\ntransition. The scaling theory of localisation and the Anderson model of\nlocalisation are briefly sketched. The finite size scaling method is described.\nRecent results for the critical exponents of the different symmetry classes are\nsummarised. The importance of corrections to scaling are emphasised. A\ncomparison with experiment is made, and a direction for future work is\nsuggested."
    },
    {
        "anchor": "Material-specific spin filtering in ferromagnet/superconductor ballistic\n  nanojunctions: We study spin-dependent electronic transport across\nferromagnet/superconductor ballistic junctions modeled using tight-binding\nHamiltonians with s, p and d orbitals and material-specific parameters. We show\nthat by accurately modeling the band structure of the bulk materials, one can\nreproduce the measured differential conductance of Cu/Pb nanocontacts. In\ncontrast the differential conductance of Co/Pb contacts can only be reproduced\nif an enhanced magnetic moment is present at the interface.",
        "positive": "Ringlike structures in the density--magnetic-field $\u03c1_{xx}$ diagram\n  of two-subband quantum Hall systems: Motivated by recent experiments [Zhang \\textit{et al.}, Phys. Rev. Lett.\n\\textbf{95}, 216801 (2005) and Ellenberger \\textit{et al.}, cond-mat/0602271]\nreporting novel ringlike structures in the density--magnetic-field\n($n_{2D}$\\emph{--B}) diagrams of the longitudinal resistivity $\\rho_{xx}$ of\nquantum wells with two subbands, we investigate theoretically here the\nmagneto-transport properties of these quantum-Hall systems. We determine\n$\\rho_{xx}$ via both the Hartree and the Kohn-Sham self-consistent schemes plus\nthe Kubo formula. While the Hartree calculation yields diamond-shaped\nstructures in the $n_{2D}$\\emph{--B} diagram, the calculation including\nexchange and correlation effects (Kohn-Sham) more closely reproduces the\nringlike structures in the experiments."
    },
    {
        "anchor": "Measurement time in double quantum dots: In this letter, we have considered an electron in a double quantum dot system\ninteracting with a detector represented by a point contact. We present a\ndynamical model for the gradual decoherence of the density matrix due to the\ninteraction with the detector. The interaction of the qubit (quantum system) on\nthe quantum point contact (environment) leads to a discrete set of pointer\nstates of the double quantum dot (apparatus). The necessary time for the qubit\ndecoherence process (measurement time) has been calculated through this model.\nThe existence of a minimum time for the quantum measurement has been obtained.",
        "positive": "Electrostatic Coupling between Two Surfaces of a Topological Insulator\n  Nanodevice: We report on electronic transport measurements of dual-gated nano-devices of\nthe low-carrier density topological insulator Bi1.5Sb0.5Te1.7Se1.3. In all\ndevices the upper and lower surface states are independently tunable to the\nDirac point by the top and bottom gate electrodes. In thin devices, electric\nfields are found to penetrate through the bulk, indicating finite capacitive\ncoupling between the surface states. A charging model allows us to use the\npenetrating electric field as a measurement of the inter-surface capacitance\n$C_{TI}$ and the surface state energy-density relationship $\\mu$(n), which is\nfound to be consistent with independent ARPES measurements. At high magnetic\nfields, increased field penetration through the surface states is observed,\nstrongly suggestive of the opening of a surface state band gap due to broken\ntime-reversal symmetry."
    },
    {
        "anchor": "Coupling of shells in a carbon nanotube quantum dot: We systematically study the coupling of longitudinal modes (shells) in a\ncarbon nanotube quantum dot. Inelastic cotunneling spectroscopy is used to\nprobe the excitation spectrum in parallel, perpendicular and rotating magnetic\nfields. The data is compared to a theoretical model including coupling between\nshells, induced by atomically sharp disorder in the nanotube. The calculated\nexcitation spectra show good correspondence with experimental data.",
        "positive": "Quantifying the Chirality of Vibrational Modes in Helical Molecular\n  Chains: The lack of quantitative methods for studying chirality has stunted our\ntheoretical understanding of chirality-induced physical phenomena. The chiral\nphonon has been proposed to be involved in various physical phenomena, but it\nis not yet well defined mathematically. Here we examine two approaches for\nassigning and quantifying the chirality of molecular normal modes in\ndouble-helical molecular wires with various levels of twist. First, associating\nwith each normal mode a structure obtained by imposing the corresponding motion\non a common atomic origin, we apply the Continuous Chirality Measure (CCM) to\nquantitatively assess the relationship between the chirality-weighted normal\nmode spectrum and the chirality of the underlying molecular structure. We find\nthat increasing the amount of twist in the double helix shifts the mean normal\nmode CCM to drastically higher values, implying that the chirality of molecular\nnormal modes is strongly correlated with that of the underlying molecular\nstructure. Second, we assign to each normal mode a pseudoscaler defined as the\nproduct of atomic linear and angular momentum summed over all atoms, and we\nanalyze the handedness of the normal mode spectrum with respect to this\nquantity. We find that twisting the double-chain structure introduces asymmetry\nbetween right and left-handed normal modes so that in twisted structures\ndifferent frequency bands are characterized by distinct handedness. This may\ngive rise to global phenomena such as thermal chirality."
    },
    {
        "anchor": "Magneto-optical properties of Au upon the injection of hot\n  spin-polarized electrons across Fe/Au(001) interfaces: We demonstrate a novel method for the excitation of sizable magneto-optical\neffects in Au by means of the laser-induced injection of hot spin-polarized\nelectrons in Au/Fe/MgO(001) heterostructures. It is based on the energy- and\nspin-dependent electron transmittance of Fe/Au interface which acts as a spin\nfilter for non-thermalized electrons optically excited in Fe. We show that\nafter crossing the interface, majority electrons propagate through the Au layer\nwith the velocity on the order of 1 nm/fs (close to the Fermi velocity) and the\ndecay length on the order of 100 nm. Featuring ultrafast functionality and\nrequiring no strong external magnetic fields, spin injection results in a\ndistinct magneto-optical response of Au. We develop a formalism based on the\nphase of the transient complex MOKE response and demonstrate its robustness in\na plethora of experimental and theoretical MOKE studies on Au, including our ab\ninitio calculations. Our work introduces a flexible tool to manipulate\nmagneto-optical properties of metals on the femtosecond timescale that holds\nhigh potential for active magneto-photonics, plasmonics, and spintronics.",
        "positive": "Impedance Matching of Atomic Thermal Interfaces Using Primitive Block\n  Decomposition: We explore the physics of thermal impedance matching at the interface between\ntwo dissimilar materials by controlling the properties of a single atomic mass\nor bond. The maximum thermal current is transmitted between the materials when\nwe are able to decompose the entire heterostructure solely in terms of\nprimitive building blocks of the individual materials. Using this approach, we\nshow that the minimum interfacial thermal resistance arises when the\ninterfacial atomic mass is the arithmetic mean, while the interfacial spring\nconstant is the harmonic mean of its neighbors. The contact induced broadening\nmatrix for the local vibronic spectrum, obtained from the self-energy matrices,\ngeneralizes the concept of acoustic impedance to the nonlinear phonon\ndispersion or the short-wavelength (atomic) limit."
    },
    {
        "anchor": "Braids and Higher-order Exceptional Points from the Interplay Between\n  Lossy Defects and Topological Boundary States: We show that the perturbation of the Su-Schrieffer-Heeger chain by a\nlocalized lossy defect leads to higher-order exceptional points (HOEPs).\nDepending on the location of the defect, third- and fourth-order exceptional\npoints (EP3s & EP4s) appear in the space of Hamiltonian parameters. On the one\nhand, they arise due to the non-Abelian braiding properties of exceptional\nlines (ELs) in parameter space. Namely, the HOEPs lie at intersections of\nmutually non-commuting ELs. On the other hand, we show that such special\nintersections happen due to the fact that the delocalization of edge states,\ninduced by the non-Hermitian defect, hybridizes them with defect states. These\ncan then coalesce together into an EP3. When the defect lies at the midpoint of\nthe chain, a special symmetry of the full spectrum can lead to an EP4. In this\nway, our model illustrates the emergence of interesting non-Abelian topological\nproperties in the multiband structure of non-Hermitian perturbations of\ntopological phases.",
        "positive": "Nonlinear simulations to optimize magnetic nanoparticle hyperthermia: Magnetic nanoparticle hyperthermia is an attractive emerging cancer\ntreatment, but the acting microscopic energy deposition mechanisms are not well\nunderstood and optimization suffers. We describe several approximate forms for\nthe characteristic time of N\\'{e}el rotations with varying properties and\nexternal influences. We then present stochastic simulations that show agreement\nbetween the approximate expressions and the micromagnetic model. The\nsimulations show nonlinear imaginary responses and associated relaxational\nhysteresis due to the field and frequency dependencies of the magnetization.\nThis suggests efficient heating is possible by matching fields to particles\ninstead of resorting to maximizing the power of the applied magnetic fields."
    },
    {
        "anchor": "Thermopower and dynamical Coulomb blockade in non-classical environments: Charge and heat transfer through a nanoscale conductor is not only determined\nby the transmission properties of the electrons, but can also be strongly\nimpacted by coupling to other degrees of freedom in the environment of the\nconductor. Here, we analyze the influence of the electromagnetic environment on\na simple, yet significant thermoelectric property, the thermopower, in the\nsimple transport scenario of single-charge transfer across a tunnel junction.\nConsidering both thermal and out-of-equilibrium steady-state environments, we\nfind that the thermopower can be strongly affected by the environmental state\nand can, in turn, act as a sensitive probe of environmental properties.",
        "positive": "Chaos and Interactions in Quantum Dots: Quantum dots are small conducting devices containing up to several thousand\nelectrons. We focus here on closed dots whose single-electron dynamics are\nmostly chaotic. The mesoscopic fluctuations of the conduction properties of\nsuch dots reveal the effects of one-body chaos, quantum coherence and\nelectron-electron interactions."
    },
    {
        "anchor": "Non-linear sigma model with particle-hole asymmetry for the disordered\n  two-dimensional electron gas: The non-linear sigma model is a well-established theoretical tool for studies\nof transport and thermodynamics in disordered electronic systems. The\nconventional sigma model approach for interacting systems does not account for\nparticle-hole asymmetry. It is therefore not suited for studying quantities\nthat are sensitive to this effect such as the thermoelectric transport\ncoefficient. Here, we derive a minimal extension of the Keldysh non-linear\nsigma model tailored for two-dimensional interacting systems. We argue that\nthis model can be used to systematically study the combined effect of\ninteractions and disorder on thermoelectric transport. As a first step in this\ndirection, we use the model to analyze the structure of the heat\ndensity-density correlation function and calculate interaction corrections to\nits static part. The calculation of interaction corrections to the dynamical\npart of the correlation function and the thermodynamic transport coefficient is\nleft for future work.",
        "positive": "Electrically tunable dynamic nuclear spin polarization in GaAs quantum\n  dots at zero magnetic field: In III-V semiconductor nano-structures the electron and nuclear spin dynamics\nare strongly coupled. Both spin systems can be controlled optically. The\nnuclear spin dynamics is widely studied, but little is known about the\ninitialization mechanisms. Here we investigate optical pumping of carrier and\nnuclear spins in charge tunable GaAs dots grown on 111A substrates. We\ndemonstrate dynamic nuclear polarization (DNP) at zero magnetic field in a\nsingle quantum dot for the positively charged exciton X$^+$ state transition.\nWe tune the DNP in both amplitude and sign by variation of an applied bias\nvoltage V$_g$. Variation of $\\Delta$V$_g$ of the order of 100 mV changes the\nOverhauser splitting (nuclear spin polarization) from -30 $\\mu$eV (-22 %) to\n+10 $\\mu$eV (+7 %), although the X$^+$ photoluminescence polarization does not\nchange sign over this voltage range. This indicates that absorption in the\nstructure and energy relaxation towards the X$^+$ ground state might provide\nfavourable scenarios for efficient electron-nuclear spin flip-flops, generating\nDNP during the first tens of ps of the X$^+$ lifetime which is of the order of\nhundreds of ps. Voltage control of DNP is further confirmed in Hanle\nexperiments."
    },
    {
        "anchor": "Observing high-k magnons with Mie-resonance-enhanced Brillouin light\n  scattering: Magnonics is a prospective beyond CMOS technology which uses magnons, the\nquanta of spin waves, for low-power information processing. Many magnonic\nconcepts and devices were recently demonstrated at macro- and microscale, and\nnow these concepts need to be realized at nanoscale. Brillouin light scattering\nspectroscopy and microscopy (BLS) has become a standard technique for spin wave\nvisualization and characterization, and enabled many pioneering magnonic\nexperiments. However, due to its fundamental limit in maximum detectable magnon\nmomentum, the conventional BLS cannot be used to detect nanoscale spin waves.\nHere we show that optically induced Mie resonances in dielectric nanoparticles\ncan be used to extend the range of accessible spin wave wavevectors beyond the\nBLS fundamental limit. The method is universal and can be used in many magnonic\nexperiments dealing with thermally excited as well as coherently excited\nhigh-momentum, short-wavelength spin waves. This discovery significantly\nextends the usability and relevance of the BLS technique for nanoscale magnonic\nresearch.",
        "positive": "Theory of the spin galvanic effect at oxide interfaces: The spin galvanic effect (SGE) describes the conversion of a non-equilibrium\nspin polarization into a transverse charge current. Recent experiments have\ndemonstrated a large conversion efficiency for the two-dimensional electron gas\nformed at the interface between two insulating oxides, LaAlO$_3$ and SrTiO$_3$.\nHere we analyze the SGE for oxide interfaces within a three-band model for the\nTi t$_{2g}$ orbitals which displays an interesting variety of effective\nspin-orbit couplings in the individual bands that contribute differently to the\nspin-charge conversion. Our analytical approach is supplemented by a numerical\ntreatment where we also investigate the influence of disorder and temperature,\nwhich turns out to be crucial to provide an appropriate description of the\nexperimental data."
    },
    {
        "anchor": "Spin transport in graphene nanostructures: Graphene is an interesting material for spintronics, showing long spin\nrelaxation lengths even at room temperature. For future spintronic devices it\nis important to understand the behavior of the spins and the limitations for\nspin transport in structures where the dimensions are smaller than the spin\nrelaxation length. However, the study of spin injection and transport in\ngraphene nanostructures is highly unexplored. Here we study the spin injection\nand relaxation in nanostructured graphene with dimensions smaller than the spin\nrelaxation length. For graphene nanoislands, where the edge length to area\nratio is much higher than for standard devices, we show that enhanced spin-flip\nprocesses at the edges do not seem to play a major role in the spin relaxation.\nOn the other hand, contact induced spin relaxation has a much more dramatic\neffect for these low dimensional structures. By studying the nonlocal spin\ntransport through a graphene quantum dot we observe that the obtained values\nfor spin relaxation are dominated by the connecting graphene islands and not by\nthe quantum dot itself. Using a simple model we argue that future nonlocal\nHanle precession measurements can obtain a more significant value for the spin\nrelaxation time for the quantum dot by using high spin polarization contacts in\ncombination with low tunneling rates.",
        "positive": "Determination of the phonon sidebands in the photoluminescence spectrum\n  of semiconductor nanoclusters from ab initio calculations: We propose a theoretical approach based on (constrained) density functional\ntheory and the Franck-Condon approximation for the calculation of the\ntemperature dependent photoluminescence of nanostructures. The method is\ncomputationally advantageous and only slightly more demanding than a standard\ndensity functional theory calculation and includes transitions into multiphonon\nfinal states (higher class transitions). We use the approach for Si and CdSe\ncolloidal nanoclusters (NCs) with up to 693 atoms and obtain very good\nagreement with experiment which allows us to identify specific peaks and\nexplain their origin. Generally, breathing type modes are shown to dominate the\nphonon replicas, while optical modes have significant contributions for CdSe\nNCs and play a lesser role in Si NCs. We obtain significant anti-Stokes peak\nstarting at 140K for Si NC explaining the broadening observed in the\ncorresponding experiment. We also apply the method to small molecular-like\ncarbon structures (diamondoids), where electron-phonon coupling is typically\nlarge, and find that multiphonon processes (up to class 4) are very relevant\nand necessary to compare favorably with experiment. While it is crucial to\ninclude these multiphonon states in the small diamondoids with few tens of\natoms, neglecting them in only marginally larger Si$_{87}$H$_{76}$ and\nCd$_{43}$Se$_{44}$H$^*_{76}$ (and larger) quantum dots represents a good\napproximation."
    },
    {
        "anchor": "Resonant versus non-resonant spin readout of a nitrogen-vacancy center\n  in diamond under cryogenic conditions: The last decade has seen an explosive growth in the use of color centers for\nmetrology applications, the paradigm example arguably being the\nnitrogen-vacancy (NV) center in diamond. Here, we focus on the regime of\ncryogenic temperatures and examine the impact of spin-selective, narrow-band\nlaser excitation on NV readout. Specifically, we demonstrate a more than\nfour-fold improvement in sensitivity compared to that possible with\nnon-resonant (green) illumination, largely due to a boost in readout contrast\nand integrated photon count. We also leverage nuclear spin relaxation under\nresonant excitation to polarize the 14N host, which we then prove beneficial\nfor spin magnetometry. These results open opportunities in the application of\nNV sensing to the investigation of condensed matter systems, particularly those\nexhibiting superconducting, magnetic, or topological phases selectively present\nat low temperatures.",
        "positive": "Chiral spin channels in curved graphene $pn$ junctions: We show that the chiral modes in circular graphene $pn$ junctions provide an\nadvantage for spin manipulation via spin-orbit coupling compared to\nsemiconductor platforms. We derive the effective Hamiltonian for the spin\ndynamics of the junction's zero modes and calculate their quantum phases. We\nfind a sweet spot in parameter space where the spin is fully in-plane and\nradially polarized for a given junction polarity. This represents a shortcut to\nsingular spin configurations that would otherwise require spin-orbit coupling\nstrengths beyond experimental reach."
    },
    {
        "anchor": "Intrinsic and extrinsic mirror symmetry breaking in anti-dot spin-wave\n  waveguides: We theoretically study the spin-wave spectra in magnonic waveguides\nperiodically patterned with square anti-dots in nanoscale with pinned\nmagnetization at the edges. We show that the breaking of the mirror symmetry of\nthe waveguide by the structural changes can result in a magnonic band gap\nclosing. These intrinsic symmetry breaking can be compensated by properly\nchosen asymmetric external bias magnetic field, i.e. in an extrinsic way. As a\nresult the magnonic gaps existing in the ideal symmetric structure can be\nrecovered. The model used for the explanation also suggests that this idea\ncould be generic both for exchange and dipolar interaction regimes of\nspin-waves and also for other types of waves, e.g., electrons in the graphene\nribbons.",
        "positive": "Crystallographic-dependent bilinear magnetoelectric resistance in a thin\n  WTe$_2$ layer: The recently reported Bilinear Magnetoeletric Resistance (BMR) in novel\nmaterials with rich spin textures, such as bismuth selenide (Bi$_2$Se$_3$) and\ntungsten ditelluride (WTe$_2$), opens new possibilities for probing the spin\ntextures via magneto-transport measurements. By its nature, the BMR effect is\ndirectly linked to the crystal symmetry of the materials and its spin texture.\nTherefore, understanding the crystallographic dependency of the effect is\ncrucial. Here we report the observation of crystallographic-dependent BMR in\nthin WTe$_2$ layers and explore how it is linked to its spin textures. The\nlinear response measured in first harmonic signals and the BMR measured in\nsecond harmonic signals are both studied under a wide range of magnitudes and\ndirections of magnetic field, applied current and at different temperatures. We\ndiscover a three-fold symmetry contribution of the BMR when current is applied\nalong the a-axis of the WTe$_2$ thin layer at 10 K, which is absent for when\ncurrent is applied along the b-axis."
    },
    {
        "anchor": "Current-induced nonequilibrium vibrations in single-molecule devices: Finite-bias electron transport through single molecules generally induces\nnonequilibrium molecular vibrations (phonons). By a mapping to a Fokker-Planck\nequation, we obtain analytical scaling forms for the nonequilibrium phonon\ndistribution in the limit of weak electron-phonon coupling $\\lambda$ within a\nminimal model. Remarkably, the width of the phonon distribution diverges as\n$\\sim\\lambda^{-\\alpha}$ when the coupling decreases, with voltage-dependent,\nnon-integer exponents $\\alpha$. This implies a breakdown of perturbation theory\nin the electron-phonon coupling for fully developed nonequilibrium. We also\ndiscuss possible experimental implications of this result such as\ncurrent-induced dissociation of molecules.",
        "positive": "Edge Magneto-Fingerprints in Disordered Graphene Nanoribbons: We report on (magneto)-transport experiments in chemically derived narrow\ngraphene nanoribbons under high magnetic fields (up to 60 Tesla). Evidences of\nfield-dependent electronic confinement features are given, and allow estimating\nthe possible ribbon edge symmetry. Besides, the measured large positive\nmagnetoconductance indicates a strong suppression of backscattering induced by\nthe magnetic field. Such scenario is supported by quantum simulations which\nconsider different types of underlying disorders (smooth edge disorder and long\nrange Coulomb scatters)."
    },
    {
        "anchor": "Comment to \"Imaging the atomic orbitals of carbon atomic chains with\n  field-emission electron microscopy\": The observation of a stable doublet pattern in the field-emission electron\nmicroscopy of a linear atomic chain requires a stable mechanism breaking the\naxial symmetry, which is not identified correctly by Mikhailovskij et al.\n[Phys. Rev. B 80, 165404 (2009)]. Using microscopic calculations, we attribute\nthe observed pattern to the symmetry breaking produced by the ligand where the\nchain is attached, plus carbon pi-bonding alternation.",
        "positive": "A singlet triplet hole spin qubit in planar Ge: Spin qubits are considered to be among the most promising candidates for\nbuilding a quantum processor. GroupIV hole spin qubits have moved into the\nfocus of interest due to the ease of operation and compatibility with Si\ntechnology. In addition, Ge offers the option for monolithic\nsuperconductor-semiconductor integration. Here we demonstrate a hole spin qubit\noperating at fields below 10 mT, the critical field of Al, by exploiting the\nlarge out-of-plane hole g-factors in planar Ge and by encoding the qubit into\nthe singlet-triplet states of a double quantum dot. We observe electrically\ncontrolled g-factor-difference-driven and exchange-driven rotations with\ntunable frequencies exceeding 100 MHz and dephasing times of 1 $\\mu$s which we\nextend beyond 150 $\\mu$s with echo techniques. These results demonstrate that\nGe hole singlet-triplet qubits are competing with state-of-the art GaAs and Si\nsinglet-triplet qubits. In addition, their rotation frequencies and coherence\nare on par with Ge single spin qubits, but they can be operated at much lower\nfields underlining their potential for on chip integration with superconducting\ntechnologies."
    },
    {
        "anchor": "Multilayer Layer Graphene Nanoribbon Flash Memory: Analysis of\n  Programming and Erasing Operation: Flash memory based on floating gate transistor is the most widely used memory\ntechnology in modern microelectronic applications. We recently proposed a new\nconcept of multilayer graphene nanoribbon (MLGNR) and carbon nanotube (CNT)\nbased floating gate transistor design for future nanoscale flash memory\ntechnology. In this paper, we analyze the tunneling current mechanism in the\nproposed graphene-CNT floating gate transistor. We anticipate that the proposed\nfloating gate transistor would adopt Fowler-Nordheim (FN) tunneling during its\nprogramming and erase operations. In this paper, we have investigated the\nmechanism of tunneling current and the factors that would influence this\ncurrent and the behavior of the proposed floating gate transistor. The analysis\nreveals that FN tunneling is a strong function of the high field induced by the\ncontrol gate, and the thicknesses of the control oxide and the tunnel oxide.",
        "positive": "Excitonic complexes in $n$-doped WS$_2$ monolayer: We investigate the origin of emission lines apparent in the low-temperature\nphotoluminescence spectra of $n$-doped WS$_2$ monolayer embedded in hexagonal\nBN layers using external magnetic fields and first-principles calculations.\nApart from the neutral A exciton line, all observed emission lines are related\nto the negatively charged excitons. Consequently, we identify emissions due to\nboth the bright (singlet and triplet) and dark (spin- and momentum-forbidden)\nnegative trions as well as the phonon replicas of the latter optically-inactive\ncomplexes. The semi-dark trions and negative biexcitons are distinguished.\nBased on their experimentally extracted and theoretically calculated\n$g$-factors, we identify three distinct families of emissions due to exciton\ncomplexes in WS$_2$: bright, intravalley and intervalley dark. The $g$-factors\nof the spin-split subbands in both the conduction and valence bands are also\ndetermined."
    },
    {
        "anchor": "Fast electron spin flips via strong subcycle electric excitation: An important goal in quantum information processing is to reduce the duration\nof quantum-logical operations. Motivated by this, we provide a theoretical\nanalysis of electrically induced fast dynamics of a single-electron spin-orbit\nqubit. We study the example of a one-dimensional quantum dot with Rashba\nspin-orbit interaction and harmonic driving, and focus on the case of strong\ndriving, when the real-space oscillation amplitude of the driven electron is\ncomparable to the width of its wave function. We provide simple approximate\nanalytical relations between the qubit Larmor frequency, the shortest\nachievable qubit-flip time, and the driving amplitude required for the shortest\nachievable qubit flip. We find that these relations compare well with results\nobtained from numerical simulations of the qubit dynamics. Based on our\nresults, we discuss practical guidelines to maximize speed and quality of\nelectric single-qubit operations on spin-orbit qubits.",
        "positive": "High-Field Shubnikov-de Haas Oscillations in the Topological Insulator\n  Bi$_2$Te$_2$Se: We report measurements of the surface Shubnikov de Haas oscillations (SdH) on\ncrystals of the topological insulator Bi$_2$Te$_2$Se. In crystals with large\nbulk resistivity ($\\sim$4 $\\Omega$cm at 4 K), we observe $\\sim$15 surface SdH\noscillations (to the $n$ = 1 Landau Level) in magnetic fields $B$ up to 45\nTesla. Extrapolating to the limit $1/B\\to 0$, we confirm the $\\frac12$-shift\nexpected from a Dirac spectrum. The results are consistent with a very small\nsurface Lande $g$-factor."
    },
    {
        "anchor": "RKKY Interactions in Graphene Landau Levels: We study RKKY interactions for magnetic impurities on graphene in situations\nwhere the electronic spectrum is in the form of Landau levels. Two such\nsituations are considered: non-uniformly strained graphene, and graphene in a\nreal magnetic field. RKKY interactions are enhanced by the lowest Landau level,\nwhich is shown to form electron states binding with the spin impurities and add\na strong non-perturbative contribution to pairwise impurity spin interactions\nwhen their separation $R$ no more than the magnetic length. Beyond this\ninteractions are found to fall off as $1/R^3$ due to perturbative effects of\nthe negative energy Landau levels. Based on these results, we develop simple\nmean-field theories for both systems, taking into account the fact that\ntypically the density of states in the lowest Landau level is much smaller than\nthe density of spin impurities. For the strain field case, we find that the\nsystem is formally ferrimagnetic, but with very small net moment due to the\nrelatively low density of impurities binding electrons. The transition\ntemperature is nevertheless enhanced by them. For real fields, the system forms\na canted antiferromagnet if the field is not so strong as to pin the impurity\nspins along the field. The possibility that the system in this latter case\nsupports a Kosterlitz-Thouless transition is discussed.",
        "positive": "Size distributions of gold nanoparticles in solution measured by\n  single-particle mass photometry: Specialized applications of nanoparticles often call for particular,\nwell-characterized particle size distributions in solution. But, this property\ncan prove difficult to measure. High-throughput methods, such as dynamic light\nscattering, detect nanoparticles in solution with an efficiency that scales\nwith diameter to the sixth power. This diminishes the accuracy of any\ndetermination that must span a range of particle sizes. The accurate\nclassification of broadly distributed systems thus requires very large numbers\nof measurements. Mass-filtered particle-sensing techniques offer a better\ndynamic range, but are labor-intensive and so have low throughput. Progress in\nmany areas of nanotechnology requires a faster, lower-cost, and more accurate\nmeasure of particle size distributions, particularly for diameters smaller than\n20 nm. Here, we present a tailored interferometric microscope system, combined\nwith a high-speed image-processing strategy, optimized for real-time particle\ntracking that determines accurate size distributions in nominal 5, 10, and 15\nnm colloidal gold nanoparticle systems by automatically sensing and classifying\nthousands of single particles sampled from solution at rates as high as 4,000\nparticles per minute. We demonstrate this method by sensing the irreversible\nbinding of gold nanoparticles to poly-D-lysine functionalized coverslips.\nVariations in the single-particle signal as a function of time and mass,\ncalibrated by TEM, show clear evidence for the presence of diffusion-limited\ntransport that most affects larger particles in solution."
    },
    {
        "anchor": "Parity and valley degeneracy in multilayer graphene: We study spatial symmetry in general ABA-stacked multilayer graphene to\nillustrate how electronic spectra at the two valleys are related in a magnetic\nfield. We show that the lattice of multilayers with an even number of layers,\nas well as that of monolayer graphene, satisfy spatial inversion symmetry,\nwhich rigorously guarantees valley degeneracy in the absence of time-reversal\nsymmetry. A multilayer with an odd number of layers (three or more) lacks\ninversion symmetry, but there is another transformation imposing an approximate\nvalley degeneracy, which arises because the low-energy Hamiltonian consists of\nseparate monolayerlike and bilayerlike parts. We show that an external\nelectrostatic potential generally breaks valley degeneracy in a magnetic field,\nin a markedly different manner in odd and even multilayers.",
        "positive": "Strong Momentum-Dependent Electron-Magnon Renormalization of a Surface\n  Resonance on Iron: The coupling of fermionic quasiparticles to magnons is essential for a wide\nrange of processes, from ultrafast magnetization dynamics in ferromagnets to\nCooper pairing in superconductors. Although magnon energies are generally much\nlarger than phonon energies, up to now their electronic band renormalization\neffect in ferromagnetic metals suggests a significantly weaker quasiparticle\ninteraction. Here, using spin- and angle-resolved photoemission, we show an\nextraordinarily strong renormalization leading to replica-band formation of an\niron surface resonance at ~200 meV. Its strong magnetic linear dichroism\nunveils the magnetic nature and momentum dependence of the energy\nrenormalization. By determining the frequency- and momentum-dependent\nself-energy due to generic electron-boson interaction to compute the resultant\nelectron spectral function, we show that the surface-state replica formation is\nconsistent with strong coupling to an optical spin wave in a Fe thin film."
    },
    {
        "anchor": "Friction force on slow charges moving over supported graphene: We provide a theoretical model that describes the dielectric coupling of a 2D\nlayer of graphene, represented by a polarization function in the Random Phase\nApproximation, and a semi-infinite 3D substrate, represented by a surface\nresponse function in a non-local formulation. We concentrate on the role of the\ndynamic response of the substrate for low-frequency excitations of the combined\ngraphene-substrate system, which give rise to the stopping force on slowly\nmoving charges above graphene. A comparison of the dielectric loss function\nwith experimental HREELS data for graphene on a SiC substrate is used to\nestimate the damping rate in graphene and to reveal the importance of phonon\nexcitations in an insulating substrate. A signature of the hybridization\nbetween graphene's pi plasmon and the substrate's phonon is found in the\nstopping force. A friction coefficient that is calculated for slow charges\nmoving above graphene on a metallic substrate shows an interplay between the\nlow-energy single-particle excitations in both systems.",
        "positive": "Nonlinear transport of ballistic Dirac electrons tunneling through a\n  tunable potential barrier in graphene: Dirac-electronic tunneling and nonlinear transport properties with both\nfinite and zero energy bandgap are investigated for graphene with a tilted\npotential barrier under a bias. For validation, results from a\nfinite-difference based numerical approach, which is developed for calculating\ntransmission and reflection coefficients with a dynamically-tunable\n(time-dependent bias field) barrier-potential profile, are compared with those\nof both an analytical model for a static square-potential barrier and a\nperturbation theory using Wentzel-Kramers-Brillouin (WKB) approximation. For a\nbiased barrier, both transmission coefficient and tunneling resistance are\ncomputed and analyzed, indicating a full control of the peak in tunneling\nresistance by bias field for a tilted barrier, gate voltage for barrier height,\nand energy for incoming electrons. Moreover, a finite energy gap in graphene is\nfound to suppress head-on transmission as well as skew transmission with a\nlarge transverse momentum. For a gapless graphene, on the other hand, filtering\nof Dirac electrons outside of normal incidence is found and can be used for\ndesigning electronic lenses. All these predicted attractive transport\nproperties are expected extremely useful for the development of novel\nelectronic and optical graphene-based devices."
    },
    {
        "anchor": "Tilted-Cone Induced Cusps and Nonmonotonic Structures in Dynamical\n  Polarization Function of Massless Dirac Fermions: The polarization function of electrons with the tilted Dirac cone found in\norganic conductors is studied using the tilted Weyl equation. The dynamical\nproperty is explored based on the analytical treatment of the particle-hole\nexcitation. It is shown that the polarization function as the function of both\nthe frequency and the momentum exhibits cusps and nonmonotonic structures. The\npolarization function depends not only on the magnitude but also the direction\nof the external momentum. These properties are characteristic of the tilted\nDirac cone, and are contrast to the isotropic case of grapheme. Further, the\nresults are applied to calculate the optical conductivity, the plasma frequency\nand the screening of Coulomb interaction, which are also strongly influenced by\nthe tilted cone.",
        "positive": "Transport in honeycomb lattice with random $\u03c0$-fluxes: implications\n  for low-temperature thermal transport in the Kitaev spin liquids: Motivated by the thermal transport problem in the Kitaev spin liquids, we\nconsider a nearest-neighbor tight-binding model on the honeycomb lattice in the\npresence of random uncorrelated $\\pi$-fluxes. We employ different numerical\nmethods to study its transport properties near half-filling. The\nzero-temperature DC conductivity away from the Dirac point is found to be\nquadratic in Fermi momentum and inversely proportional to the flux density.\nLocalization due to the random $\\pi$-fluxes is observed and the localization\nlength is extracted. Our results imply that, for realistic system size, the\nthermal conductivity of a pure Kitaev spin liquid diverges as\n$\\kappa_\\text{K}\\sim T^3 e^{\\Delta_v/k_BT}$ when $k_B T\\ll \\Delta_v$, and\nsuggest the possible occurrence of strong Majorana localization\n$\\kappa_\\text{K}/T\\ll k_B^2/2\\pi\\hbar$ when $k_B T\\sim \\Delta_v$, where\n$\\Delta_v$ is the vison gap."
    },
    {
        "anchor": "Pronounced photovoltaic response from multi-layered transition-metal\n  dichalcogenides PN-junctions: Transition metal dichalcogenides (TMDs) are layered semiconductors with\nindirect band gaps comparable to Si. These compounds can be grown in large\narea, while their gap(s) can be tuned by changing their chemical composition or\nby applying a gate voltage. The experimental evidence collected so far, points\ntowards a strong interaction with light, which contrasts with the small\nphotovoltaic efficiencies $\\eta \\geq 1$ % extracted from bulk crystals or\nexfoliated monolayers. Here, we evaluate the potential of these compounds by\nstudying the photovoltaic response of electrostatically generated PN-junctions\ncomposed of approximately ten atomic-layers of MoSe$_2$ stacked onto the\ndielectric $h$-BN. In addition to ideal diode-like response, we find that these\njunctions can yield, under AM-1.5 illumination, photovoltaic efficiencies\n$\\eta$ exceeding 14 %, with fill-factors of ~ 70 %. Given the available\nstrategies for increasing $\\eta$ such as gap tuning, improving the quality of\nthe electrical contacts, or the fabrication of tandem cells, our study suggests\na remarkable potential for photovoltaic applications based on TMDs.",
        "positive": "Plasmons enhance near-field radiative heat transfer for graphene-covered\n  dielectrics: It is shown that a graphene layer on top of a dielectric slab can\ndramatically influence the ability of this dielectric for radiative heat\nexchange. Effect of graphene is related to thermally excited plasmons.\nFrequency of these resonances lies in the terahertz region and can be tuned by\nvarying the Fermi level through doping or gating. Heat transfer between two\ndielectrics covered with graphene can be larger than that between best known\nmaterials and even much larger at low temperatures. Moreover, high heat\ntransfer can be significantly modulated by electrical means that opens up new\npossibilities for very fast manipulations with the heat flux."
    },
    {
        "anchor": "Theory of quantum energy transfer in spin chains: From superexchange to\n  ballistic motion: Quantum energy transfer in a chain of two-level (spin) units, connected at\nits ends to two thermal reservoirs, is analyzed in two limits: (i) In the\noff-resonance regime, when the characteristic subsystem excitation energy gaps\nare larger than the reservoirs frequencies, or the baths temperatures are low.\n(ii) In the resonance regime, when the chain excitation gaps match populated\nbath modes. In the latter case the model is studied using a master equation\napproach, showing that the dynamics is ballistic for the particular chain model\nexplored. In the former case we analytically study the system dynamics\nutilizing the recently developed Energy-Transfer Born-Oppenheimer formalism\n[Phys. Rev. E {\\bf 83}, 051114 (2011)], demonstrating that energy transfers\nacross the chain in a superexchange (bridge assisted tunneling) mechanism, with\nthe energy current decreasing exponentially with distance. This behavior is\ninsensitive to the chain details. Since at low temperatures the excitation\nspectrum of molecular systems can be truncated to resemble a spin chain model,\nwe argue that the superexchange behavior obtained here should be observed in\nwidespread systems satisfying the off-resonance condition.",
        "positive": "Insight of the Green's function as a defect state in a boundary value\n  problem: A new perspective of the Green's function in a boundary value problem as the\nonly eigenstate in an auxiliary formulation is introduced. In this treatment,\nthe Green's function can be perceived as a defect state in the presence of a\n$\\delta$-function potential, the height of which depends on the Green's\nfunction itself. This approach is illustrated in one-dimensional and\ntwo-dimensional Helmholtz equation problems, with an emphasis on systems that\nare open and have a non-Hermitian potential. We then draw an analogy between\nthe Green's function obtained this way and a chiral edge state circumventing a\ndefect in a topological lattice, which shines light on the local minimum of the\nGreen's function at the source position."
    },
    {
        "anchor": "Anisotropic magneto-Coulomb effect versus spin accumulation in a\n  ferromagnetic single-electron device: We investigate the magneto-transport characteristics of nanospintronics\nsingle-electron devices. The devices consist of single non-magnetic\nnano-objects (nanometer size nanoparticles of Al or Cu) connected to Co\nferromagnetic leads. The comparison with simulations allows us attribute the\nobserved magnetoresistance to either spin accumulation or anisotropic\nmagneto-Coulomb effect (AMC), two effects with very different origins. The fact\nthat the two effects are observed in similar samples demonstrates that a\ncareful analysis of Coulomb blockade and magnetoresistance behaviors is\nnecessary in order to discriminate them in magnetic single-electron devices. As\na tool for further studies, we propose a simple way to determine if spin\ntransport or AMC effect dominates from the Coulomb blockade I-V curves of the\nspintronics device.",
        "positive": "Microwave-induced electron heating in the regime of radiation-induced\n  magnetoresistance oscillations: We examine the influence of microwave photoexcitation on the amplitude of\nShubnikov-de Haas (SdH) oscillations in a two dimensional GaAs/AlGaAs electron\nsystem in a regime where the cyclotron frequency, $\\omega_{c}$, and the\nmicrowave angular frequency, $\\omega$, satisfy $2 \\omega \\le \\omega_{c} \\le 3.5\n\\omega$. A SdH lineshape analysis indicates that increasing the incident\nmicrowave power has a weak effect on the amplitude of the SdH oscillations, in\ncomparison to the influence of modest temperature changes on the dark-specimen\nSdH effect. The results indicate negligible electron heating under modest\nmicrowave photoexcitation, in good agreement with theoretical predictions."
    },
    {
        "anchor": "Kondo effect and spin-orbit coupling in graphene quantum dots: The Kondo effect is a cornerstone in the study of strongly correlated\nfermions. The coherent exchange coupling of conduction electrons to local\nmagnetic moments gives rise to a Kondo cloud that screens the impurity spin.\nWhereas complete Kondo screening has been explored widely, realizations of the\nunderscreened scenario - where only some of several Kondo channels participate\nin the screening - remain rare. Here we report the observation of fully\nscreened and underscreened Kondo effects in quantum dots in bilayer graphene.\nMore generally, we introduce a unique platform for studying Kondo physics. In\ncontrast to carbon nanotubes, whose curved surfaces give rise to strong\nspin-orbit coupling breaking the SU(4) symmetry of the electronic states\nrelevant for the Kondo effect, we study a nominally flat carbon material with\nsmall spin-orbit coupling. Moreover, the unusual two-electron triplet ground\nstate in bilayer graphene dots provides a route to exploring the underscreened\nspin-1 Kondo effect.",
        "positive": "Orbital mechanism of the circular photogalvanic effect in quantum wells: It is shown that the free-carrier (Drude) absorption of circularly polarized\nradiation in quantum well structures leads to an electric current flow. The\nphotocurrent reverses its direction upon switching the light helicity. A pure\norbital mechanism of such a circular photogalvanic effect is proposed that is\nbased on interference of different pathways contributing to the light\nabsorption. Calculation shows that the magnitude of the helicity dependent\nphotocurrent in $n$-doped quantum well structures corresponds to recent\nexperimental observations."
    },
    {
        "anchor": "Rashba controlled two-electron spin-charge qubits as building blocks of\n  a quantum computer: The spin-sensitive charge oscillation, controlled by an external magnetic\nfield, was recently proposed as a mechanism of transformations of qubits,\ndefined as two-electron spin-charge Wannier molecules in a square quantum dot.\nThe paper expands this idea by including the effects of Rashba type spin-orbit\ncoupling. The problem is studied theoretically by mapping the system to an\nanalytic effective Hamiltonian for 8 low energy states, comprising singlet and\ntriplet on each dot diagonal. The validity of the mapping is confirmed by\ncomparing the energy and spin of full and mapped system, and also by the\nreproduction of charge-oscillation dynamics in the presence of magnetic flux.\nThe newly introduced Rashba coupling significantly enriches the system\ndynamics, affecting the magnitude of charge oscillations and allowing the\ncontrolled transitions between singlet and triplet states due to the spin\nrotations, induced by spin-orbit coupling. The results indicate the possibility\nfor use of the studied system for quantum information processing, while\npossible extensions of the system to serve as a qubit in a universal quantum\ncomputer, fulfilling all five DiVincenzo criteria, are also discussed.",
        "positive": "Hexagonal Warping Induced Nonlinear Planar Nernst Effect in Nonmagnetic\n  Topological Insulators: We propose theoretically a new effect, i.e. nonlinear planar Nernst effect\n(NPNE), in nonmagnetic topological insulator (TI) Bi2Te3 in the presence of an\nin-plane magnetic field. We find that the Nernst current scales quadratically\nwith temperature gradient but linearly with magnetic field and exhibits a\ncosine dependence of the orientation of the magnetic field with respect to the\ndirection of the temperature gradient. The NPNE has a quantum origin arising\nfrom the conversion of a nonlinear transverse spin current to a charge current\ndue to a joint result of hexagonal warping effect, spin-momentum locking, and\nthe time-reversal symmetry breaking induced by the magnetic field."
    },
    {
        "anchor": "Electrostatic Conveyer for Excitons: We report on the study of indirect excitons in moving lattices - conveyers\ncreated by a set of AC voltages applied to the electrodes on the sample\nsurface. The wavelength of this moving lattice is set by the electrode\nperiodicity, the amplitude is controlled by the applied voltage, and the\nvelocity is controlled by the AC frequency. We observed the dynamical\nlocalization-delocalization transition for excitons in the conveyers and\nmeasured its dependence on the exciton density and conveyer amplitude and\nvelocity. We considered a model for exciton transport via conveyers. The\ntheoretical simulations are in agreement with the experimental data.",
        "positive": "Curvature-induced Rashba spin-orbit interaction in strain-driven\n  nanostructures: We derive the effective dimensionally reduced Schr\\\"odinger equation with\nspin-orbit interaction in low-dimensional electronic strain driven\nnanostructures. A method of adiabatic separation among fast normal quantum\ndegrees of freedom and slow tangential quantum degrees of freedom is used to\nshow the emergence of a strain-induced Rashba-like spin-orbit interaction\n(SOI). By applying this analysis to one-dimensional curved quantum wires we\ndemonstrate that the curvature-induced Rashba SOI leads to enhanced spin-orbit\neffects."
    },
    {
        "anchor": "Scaling Theory of Two-Dimensional Field Effect Transistors: We present a scaling theory of two-dimensional (2D) field effect transistors\n(FETs). For devices with channel thickness less than 4 nm, the device\nelectrostatics is dominated by the physical gate oxide thickness and not the\neffective oxide thickness. Specifically, for symmetric double gate (DG) FETs\nthe scale length ({\\Lambda}) varies linearly with the gate oxide\nthickness(t_{ox}) as {\\Lambda} ~ 3/4t_{ox}. The gate oxide dielectric\npermittivity and the semiconductor channel thickness do not affect the device\nelectrostatics for such device geometries. For an asymmetric device such as\nsingle gate (SG) FETs, the fringing fields have a second order effect on the\nscale length. However, like symmetric DG FETs, the scale length in asymmetric\nFETs is also ultimately limited by the physical gate oxide thickness. We\ncompare our theoretical predictions for scaled monolayer MoS2 DG FETs.",
        "positive": "Transverse Electronic Transport through DNA Nucleotides with\n  Functionalized Graphene Electrodes: Graphene nanogaps and nanopores show potential for the purpose of electrical\nDNA sequencing, in particular because single-base resolution appears to be\nreadily achievable. Here, we evaluated from first principles the advantages of\na nanogap setup with functionalized graphene edges. To this end, we employed\ndensity functional theory and the non-equilibrium Green's function method to\ninvestigate the transverse conductance properties of the four nucleotides\noccurring in DNA when located between the opposing functionalized graphene\nelectrodes. In particular, we determined the electrical tunneling current\nvariation as a function of the applied bias and the associated differential\nconductance at a voltage which appears suitable to distinguish between the four\nnucleotides. Intriguingly, we observe for one of the nucleotides a negative\ndifferential resistance effect."
    },
    {
        "anchor": "Kondo peaks and dips in the differential conductance of a multi-lead\n  quantum dot: Dependence on bias conditions: We study the differential conductance in the Kondo regime of a quantum dot\ncoupled to multiple leads. When the bias is applied symmetrically on two of the\nleads ($V$ and $-V$, as usual in experiments), while the others are grounded,\nthe conductance through the biased leads always shows the expected enhancement\nat {\\it zero} bias. However, under asymmetrically applied bias ($V$ and\n$\\lambda V$, with $\\lambda>0$), a suppression - dip - appears in the\ndifferential conductance if the asymmetry coefficient $\\lambda$ is beyond a\ngiven threshold $\\lambda_0= \\sqrt[3]{1+r}$ determined by the ratio $r$ of the\ndot-leads couplings. This is a recipe to determine experimentally this ratio\nwhich is important for the quantum-dot devices. This finding is a direct result\nof the Keldysh transport formalism. For the illustration we use a many-lead\nAnderson Hamiltonian, the Green functions being calculated in the Lacroix\napproximation, which is generalized to the case of nonequilibrium.",
        "positive": "Coherent Resonant Tunneling Through an Artificial Molecule: Coherent resonant tunneling through an artificial molecule of quantum dots in\nan inhomogeneous magnetic field is investigated using an extended Hubbard\nmodel. Both the multiterminal conductance of an array of quantum dots and the\npersistent current of a quantum dot molecule embedded in an Aharanov-Bohm ring\nare calculated. The conductance and persistent current are calculated\nanalytically for the case of a double quantum dot and numerically for larger\narrays using a multi-terminal Breit-Wigner type formula, which allows for the\nexplicit inclusion of inelastic processes. Cotunneling corrections to the\npersistent current are also investigated, and it is shown that the sign of the\npersistent current on resonance may be used to determine the spin quantum\nnumbers of the ground state and low-lying excited states of an artificial\nmolecule. An inhomogeneous magnetic field is found to strongly suppress\ntransport due to pinning of the spin-density-wave ground state of the system,\nand giant magnetoresistance is predicted to result from the ferromagnetic\ntransition induced by a uniform external magnetic field."
    },
    {
        "anchor": "Electron Transmission Across Normal Metal-Strained Graphene-Normal Metal\n  Junctions: The transmission of the electron across the single normal metal-graphene (NG)\nand normal-metal-graphene-normal-metal (NGN) junctions has been investigated.\nFor the single NG junction, the profile of the maximum transmission which has\nbeen plotted against the dimensionless interface hopping respectively bears\nsimilarity to that of the conductance of the system. The minor effect of the\nincidence energy on transmission can also be found in conductance of the single\nNG junction whose tunneling behavior poses a striking difference from that of\nthe NGN junction. Concerning with NGN junction, the transmission and\nconductance show more abundant structures when subjected to different incidence\nenergies, interface hopping, and strain strengths. The increase of strain\nstrength always induces more resonance peaks at different angles in\ntransmission and can therefore enhance the conductance. The increase of length\nof the middle graphene segment can accommodate more quasi-resonance states,\nleading to the more resonance peaks and richer structures in transmission. In\nboth single NG and NGN junctions, the increase of the wavefunction period on\nmetal side(s) can be observed due to the enhancement of strain strength, which\ncan serve as the sensor for the detection of the strain strength in graphene.",
        "positive": "Generalized two-temperature model for coupled phonons: The design of graphene-based composite with high thermal conductivity\nrequires a comprehensive understanding of phonon coupling in graphene. We\nextended the two-temperature model to coupled groups of phonon. The study give\nnew physical quantities, the phonon-phonon coupling factor and length, to\ncharacterize the couplings quantitatively. Besides, our proposed coupling\nlength has an obvious dependence on system size. Our studies can not only\nobserve the nonequilibrium between different groups of phonon, but explain\ntheoretically the thermal resistance inside graphene."
    },
    {
        "anchor": "Electron paths and double-slit interference in the scanning gate\n  microscopy: We analyze electron paths in a solid-state double-slit interferometer based\non the two-dimensional electron gas and their mapping by the scanning gate\nmicroscopy (SGM). A device with a quantum point source contact of a split exit\nand a drain contact used for electron detection is considered. We study the SGM\nmaps of source-drain conductance ($G$) as functions of the probe position and\nfind that for a narrow drain the classical electron paths are clearly resolved\nbut without any trace of the double-slit interference. The latter is present in\nthe SGM maps of backscattering ($R$) probability only. The double-slit\ninterference is found in the $G$ maps for a wider drain contact but at the\nexpense of the loss of information on the electron trajectories. Stability of\n$G$ and $R$ maps versus the geometry parameters of the scattering device is\nalso discussed. We discuss the interplay of the Young interference and\ninterference effects between various electron paths introduced by the tip and\nthe electron detector.",
        "positive": "Quantum Nonlinear Ferroic Optical Hall Effect: Nonlinear optical responses to external electromagnetic field, characterized\nby second and higher order susceptibilities, play crucial roles in nonlinear\noptical devices and novel optoelectronics. Herein we present a quantum\nnonlinear ferroic optical Hall effect (QNFOHE) in multiferroics - a Hall-like\ndirect photocurrent originated from the second order current response to\nintense electromagnetic field whose direction can be controlled by both\ninternal ferroic orders and external light polarization. QNFOHE consists of two\ntypes of nonlinear photocurrent responses - shift current and circular\nphotocurrent under linearly and circularly polarized light irradiation\ndominated by topological shift vector and Berry curvature, respectively. We\nelucidate the microscopic mechanism of QNFOHE in a representative class of 2D\nmultiferroic materials using group theoretical analyses and first-principles\nelectronic structure theory. The complex interplay of crystalline, permutation,\ngauge, and time reversal symmetries as well as inherent causality governs the\nsymmetry properties of shift current and circular photocurrent. QNFOHE combined\nwith rich ferroic degrees of freedom in multiferroic materials will open up a\nvariety of new avenues for realizing tunable and configurable nonlinear\noptoelectronics etc."
    },
    {
        "anchor": "Inner and outer edge states in graphene rings: A numerical investigation: We numerically investigate quantum rings in graphene and find that their\nelectronic properties may be strongly influenced by the geometry, the edge\nsymmetries and the structure of the corners. Energy spectra are calculated for\ndifferent geometries (triangular, hexagonal and rhombus-shaped graphene rings)\nand edge terminations (zigzag, armchair, as well as the disordered edge of a\nround geometry). The states localized at the inner edges of the graphene rings\ndescribe different evolution as a function of magnetic field when compared to\nthose localized at the outer edges. We show that these different evolutions are\nthe reason for the formation of sub-bands of edge states energy levels,\nseparated by gaps (anticrossings). It is evident from mapping the charge\ndensities that the anticrossings occur due to the coupling between inner and\nouter edge states.",
        "positive": "Spectroscopy, Interactions and Level Splittings in Au Nanoparticles: We have measured the electronic energy spectra of nm-scale Au particles using\na new tunneling spectroscopy configuration. The particle diameters ranged from\n5nm to 9nm, and at low energies the spectrum is discrete, as expected by the\nelectron-in-a-box model. The density of tunneling resonances increases rapidly\nwith energy, and at higher energies the resonances overlap forming broad\nresonances. Near the Thouless energy, the broad resonances merge into a\ncontinuum. The tunneling resonances display Zeeman splitting in a magnetic\nfield. Surprisingly, the g-factors (~0.3) of energy levels in Au nano-particles\nare much smaller than the g-factor (2.1) in bulk gold."
    },
    {
        "anchor": "Absolute negative conductivity in two-dimensional electron systems under\n  microwave radiation: We overview mechanisms of absolute negative conductivity in two-dimensional\nelectron systems in a magnetic field irradiated with microwaves and provide\nplausible explanations of the features observed in recent experiments related\nto the so-called zero-resistance (zero-conductance) states.",
        "positive": "Effects of anisotropy on the high field magnetoresistance of Weyl\n  semimetals: We study the effects of anisotropy on the magnetoresistance of Weyl\nsemimetals (WSMs) in the ultraquantum regime. We utilize the fact that many\nWeyl semimetals are approximately axially anisotropic. We find that anisotropy\nmanifests itself in the strong dependence of the magnetoresistance on the polar\nand azimuthal angles determining the orientation of the anisotropy axis with\nrespect to the applied magnetic field and electric current. We also predict\nthat the ratio of magnetoresistances in the geometries, where the magnetic\nfield and anisotropy axes are aligned and where they are orthogonal, scales as\n$(v_\\bot/v_\\parallel)^2$ where $v_\\bot$ and $v_\\parallel$ are the corresponding\nFermi velocities."
    },
    {
        "anchor": "Epitaxial Graphene Nanoribbons on Bunched Steps of a 6H-SiC(0001)\n  Substrate: Aromatic Ring Pattern and Van Hove Singularities: We report scanning tunneling microscopy and spectroscopy investigation of\ngraphene nanoribbons grown on an array of bunched steps of a 6H-SiC(0001)\nsubstrate. Our scanning tunneling microscopy images of a graphene nanoribbons\non a step terrace feature a (sqrt(3)x sqrt(3))R30{\\deg} pattern of aromatic\nrings which define our armchair nanoribbons. This is in agreement to a\nsimulation based on density functional theory. As another signature of the\none-dimensional electronic structure, in the corresponding scanning tunneling\nspectroscopy spectra we find well developed, sharp Van Hove singularities.",
        "positive": "Minimal alternating current injection into carbon nanotubes: We study theoretically the effect of electronic interactions in 1d systems on\nelectron injection using periodic Lorentzian pulses, known as Levitons. We\nconsider specifically a system composed of a metallic single-wall carbon\nnanotube, described with the Luttinger liquid formalism, a scanning tunneling\nmicroscope (STM) tip, and metallic leads. Using the out-of-equilibrium Keldysh\nGreen function formalism, we compute the current and current noise in the\nsystem. We prove that the excess noise vanishes when each Leviton injects an\ninteger number of electrons from the STM tip into the nanotube. This extends\nthe concept of minimal injection with Levitons to strongly correlated,\nuni-dimensional non-chiral systems. We also study the time-dependent current\nprofile, and show how it is the result of interferences between pulses\nnon-trivially reflected at the nanotube-lead interface."
    },
    {
        "anchor": "Spin-orbit interaction in InSb nanowires: We use magnetoconductance measurements in dual-gated InSb nanowire devices\ntogether with a theoretical analysis of weak antilocalization to accurately\nextract spin-orbit strength. In particular, we show that magnetoconductance in\nour three-dimensional wires is very different compared to wires in\ntwo-dimensional electron gases. We obtain a large Rashba spin-orbit strength of\n$0.5 -1\\,\\text{eV\\r{A}}$ corresponding to a spin-orbit energy of\n$0.25-1\\,\\text{meV}$. These values underline the potential of InSb nanowires in\nthe study of Majorana fermions in hybrid semiconductor-superconductor devices.",
        "positive": "Theory of the strong coupling between quantum emitters and propagating\n  surface plasmons: Here we present the theoretical foundation of the strong coupling phenomenon\nbetween quantum emitters and propagating surface plasmons observed in\ntwo-dimensional metal surfaces. For that purpose, we develop an ab-initio\nquantum framework that accounts for the coherent coupling be- tween emitters\nand surface plasmons and incorporates the presence of dissipation and\ndephasing. For both a single emitter and a disordered ensemble of emitters, our\nformalism is able to reveal the key physical mechanisms that explain the\nreported phenomenology and also to determine the physical parameters that\noptimize the strong coupling."
    },
    {
        "anchor": "Theoretical approach to micro wave radiation-induced zero-resistance\n  states in 2D electron systems: We present a theoretical model in which the existence of radiation-induced\nzero-resistance states is analyzed. An exact solution for the harmonic\noscillator wave function in the presence of radiation, and a perturbation\ntreatment for elastic scattering due to randomly distributed charged\nimpurities, form the foundations of our model. Following this model most\nexperimental results are reproduced, including the formation of resistivity\noscillations, their dependence on the intensity and frequency of the radiation,\ntemperature effects, and the locations of the resistivity minima. The existence\nof zero-resistance states is thus explained in terms of the interplay of the\nelectron MW-driven orbit dynamics and the Pauli exclusion principle.",
        "positive": "Evidence of universality in the dynamical response of micromechanical\n  diamond resonators at millikelvin temperatures: We report kelvin to millikelvin-temperature measurements of dissipation and\nfrequency shift in megahertz-range resonators fabricated from\nultra-nanocrystalline diamond. Frequency shift $\\delta f/f_0$ and dissipation\n$Q^{-1}$ demonstrate temperature dependence in the millikelvin range similar to\nthat predicted by the glass model of tunneling two level systems. The\nlogarithmic temperature dependence of $\\delta f/ f_0$ is in good agreement with\nsuch models, which include phonon relaxation and phonon resonant absorption.\nDissipation shows a weak power law, $Q^{-1}\\propto T^{{1/3}}$, followed by\nsaturation at low temperature. A comparison of both the scaled frequency shift\nand dissipation in equivalent micromechanical structures made of single-crystal\nsilicon and gallium arsenide indicates universality in the dynamical response."
    },
    {
        "anchor": "Hamiltonian Phase Error in Resonantly Driven CNOT Gate Above the\n  Fault-Tolerant Threshold: Because of their long coherence time and compatibility with industrial\nfoundry processes, electron spin qubits are a promising platform for scalable\nquantum processors. A full-fledged quantum computer will need quantum error\ncorrection, which requires high-fidelity quantum gates. Analyzing and\nmitigating the gate errors are useful to improve the gate fidelity. Here, we\ndemonstrate a simple yet reliable calibration procedure for a high-fidelity\ncontrolled-rotation gate in an exchange-always-on Silicon quantum processor\nallowing operation above the fault-tolerance threshold of quantum error\ncorrection. We find that the fidelity of our uncalibrated controlled-rotation\ngate is limited by coherent errors in the form of controlled-phases and present\na method to measure and correct these phase errors. We then verify the\nimprovement in our gate fidelities by randomized benchmark and gate-set\ntomography protocols. Finally, we use our phase correction protocol to\nimplement a virtual, high-fidelity controlled-phase gate.",
        "positive": "Wannier Diagram and Brown-Zak Fermions of Graphene on Hexagonal\n  Boron-Nitride: The moir\\'e potential of graphene on hexagonal boron nitride (hBN) generates\na supercell sufficiently large as to thread a full magnetic flux quantum\n$\\Phi_0$ for experimentally accessible magnetic field strengths. Close to\nrational fractions of $\\Phi_0$, $p/q \\cdot\\Phi_0$, magnetotranslation\ninvariance is restored giving rise to Brown-Zak fermions featuring the same\ndispersion relation as in the absence of the field. Employing a highly\nefficient numerical approach we have performed the first realistic simulation\nof the magnetoconductance for a 250 nm wide graphene ribbon on hexagonal boron\nnitride using a full ab-initio derived parametrization including strain. The\nresulting Hofstadter butterfly is analyzed in terms of a novel Wannier diagram\nfor Landau spectra of Dirac particles that includes the lifting of the spin and\nvalley degeneracy by the magnetic field and the moir\\'e potential. This complex\ndiagram can account for many experimentally observed features on a\nsingle-particle level, such as spin and valley degeneracy lifting and a\nnon-periodicidy in $\\Phi_0$."
    },
    {
        "anchor": "Direct Experimental Evidence of the Statistical Nature of the Electron\n  Gas in Superconducting Films: In an Nb film an alternate electrical current is partitioned at a Y-shaped\nobstacle into two splitted beams. The intensity-fluctuation correlation of the\ntwo beams (cross-correlation) and the intensity- fluctuation correlation of one\nbeam (auto-correlation) are measured within a low-frequency bandwidth as a\nfunction of the incident beam intensity, at temperatures T above or below the\ntemperature Tc of the superconductive transition. The results of these\nmeasurements reveal the statistical nature of the electron gas in the normal\nfilm and in the superconducting film. The conceptual scheme of the present\nexperiment is a version of the Hanbury Brown and Twiss (HBT) experiment, here\nadopted for a gas of particles in a solid.",
        "positive": "Interference Blockade in the Conductance of Organic Molecules: The conductance of {\\em cis/trans} isomers of stilbene molecules connected to\narmchair single wall carbon nanotubes is studied in the Landauer formalism\ncombined with a density-functional based approach. For a given arrangement of\nthe electrodes, dramatic differences in the transmission between both isomers\nare found. For a given isomer, the conductance can be varied by orders of\nmagnitude by changing the molecule-electrode relative orientation. Both effects\ncan be explained by a simple, physically transparent interference rule, which\nsuggests a straightforward conductance control in such molecular systems by\ndifferent switching mechanisms."
    },
    {
        "anchor": "Parametric Auto-Excitation of Magnetic Droplet Soliton Perimeter Modes: Recent experiments performed in current-driven nano-contacts with strong\nperpendicular anisotropy have shown that spin-transfer torque can drive\nself-localized spin waves [1, 2] that above a certain threshold intensity can\ncondense into a highly nonlinear magnetodynamic and nano-sized state known as a\nmagnetic droplet soliton [3]. Here we demonstrate analytically, numerically,\nand experimentally that at sufficiently large driving currents, and for a spin\npolarization that is tilted away from the film normal, the circular droplet\nsoliton can become unstable to periodic excitations of its perimeter. We\nfurthermore show that these perimeter excitation modes (PEMs) are\nparametrically excited when the fundamental droplet soliton precession\nfrequency is close to twice the frequency of one or more of the PEMs. As a\nconsequence, for increasing applied fields, progressively higher PEMs can be\nexcited. Quantitative agreement with experiment confirms this picture.",
        "positive": "Coherent Controllable Transport of a Surface Plasmon Coupled to\n  Plasmonic Waveguide with a Metal Nano Particle-Semiconductor Quantum Dot\n  Hybrid System: By using the real-space method, switching of a single plasmon interacting\nwith a hybrid nanosystem composed of a semiconductor quantum dot (SQD) and a\nmetallic nanoparticle (MNP) coupled to one-dimensional surface plasmonic\nwaveguide is investigated theoretically. We discussed that the dipole coupling\nbetween an exciton and a localized surface plasmon results in the formation of\na hybrid exciton and the transmission and reflection of the propagating single\nplasmon could be controlled by changing the interparticle distance between the\nSQD and the MNP and the size of the nanoparticles. The controllable transport\nof the propagating single surface plasmon by such a nanosystem discussed here\ncould find the significant potential in the design of next-generation quantum\ndevices such as plasmonic switch, single photon transistor and nanolaser and\nquantum information."
    },
    {
        "anchor": "Microscopic Description of Coherent Transport by Thermal Phonons: We demonstrate the coherent transport of thermal energy in superlattices by\nintroducing a microscopic definition of the phonon coherence length. We\ndemonstrate how to distinguish a coherent transport regime from diffuse\ninterface scattering and discuss how these can be specifically controlled by\nseveral physical parameters. Our approach provides a convenient framework for\nthe interpretation of previous experiments and thermal conductivity\ncalculations and paves the way for the design of a new class of thermal\ninterface materials.",
        "positive": "Driving field amplitude gauged quantitative inverse spin Hall effect\n  detection: Spin transport in thin-film materials can be studied by ferromagnetic\nresonantly (FMR) driven spin pumping of a charge-free spin current which\ninduces an electromotive force through the inverse spin Hall effect (ISHE). For\nquantitative ISHE experiments, precise control of the FMR driving field\namplitude $B_1$ is crucial. This study exploits in situ monitoring of $B_1$ by\nutilization of electron paramagnetic resonantly (EPR) induced transient\nnutation of paramagnetic molecules (a 1:1 complex of\n{\\alpha},{\\gamma}-bisdiphenylene-{\\beta}-phenylallyl and benzene, BDPA) placed\nas $B_1$ probe in proximity of a NiFe/Pt-based ISHE device. Concurrent to an\nISHE experiment, $B_1$ is obtained from the inductively measured BDPA\nRabi-nutation frequency. Higher reproducibility is achieved by renormalization\nof the ISHE voltage to $B_1^2$ with an accuracy that is determined by the\nhomogeneity of the FMR driving field and thus by the applied microwave\nresonator and ISHE device setup."
    },
    {
        "anchor": "Dipole excitation of collective modes in viscous two-dimensional\n  electron systems: We describe the structure of the time-harmonic electromagnetic field of a\nvertical Hertzian electric dipole source radiating over an infinite,\ntranslation invariant two-dimensional electron system. Our model for the\nelectron flow takes into account the effects of shear and Hall viscosities as\nwell as an external static magnetic field perpendicular to the sheet. We\nidentify two wave modes, namely, a surface plasmon and a diffusive mode. In the\npresence of an external static magnetic field, the diffusive mode combines the\nfeatures of both the conventional and Hall diffusion and may exhibit a negative\ngroup velocity. In our analysis, we solve exactly a boundary value problem for\nthe time-harmonic Maxwell equations coupled with linearized hydrodynamic\nequations for the flat, two-dimensional material. By numerically evaluating the\nintegrals for the electromagnetic field on the sheet, we find that the plasmon\ncontribution dominates in the intermediate-field region of the dipole source.\nIn contrast, the amplitude of the diffusive mode reaches its maximum value in\nthe near-field region, and quickly decays with the distance from the source. We\ndemonstrate that the diffusive mode can be distinguished from the plasmon in\nthe presence of the static magnetic field, when the highly oscillatory plasmon\nis gapped and tends to disappear.",
        "positive": "Valley Acoustoelectric Effect: We report on novel valley acoustoelectric effect, which can arise in a 2D\nmaterial, like a transition metal dichalcogenide monolayer, residing on a\npiezoelectric substrate. The essence of this effect lies in the emergence of a\ndrag electric current (and a spin current) due to a propagating surface\nacoustic wave. This current consists of three contributions, one independent of\nthe valley index and proportional to the acoustic wave vector, the other\narising due to the trigonal warping of the electron dispersion, and the third\none is due to the Berry phase, which Bloch electrons acquire traveling along\nthe crystal. As a result, there appear components of the current orthogonal to\nthe acoustic wave vector. Further, we build an angular pattern, encompassing\nnontrivial topological properties of the acoustoelectric current, and suggest a\nway to run and measure the conventional diffusive, warping, and acoustoelectric\nvalley Hall currents independently. We develop a theory, which opens a way to\nmanipulate valley transport by acoustic methods, expanding the applicability of\nvalleytronic effects on acoustoelectronic devices."
    },
    {
        "anchor": "Theoretical study of strain-dependent optical absorption in\n  Stranski-Krastanov grown InAs/InGaAs/GaAs/AlGaAs quantum dots: A detailed theoretical study of the optical absorption in self-assembled\nquantum dots is presented in this paper. A rigorous atomistic strain model as\nwell as a sophisticated electronic band structure model are used to ensure\naccurate prediction of the optical transitions in these devices . The optimized\nmodels presented in this paper are able to reproduce the experimental results\nwith an error less than 1$\\%$. The effects of incident light polarization,\nalloy mole fraction, quantum dot dimensions, and doping have been investigated.\nThe in-plane polarized light absorption is more significant than the\nperpendicularly polarized light absorption. Increasing the mole fraction of the\nstrain controlling layer leads to a lower energy gap and larger absorption\nwavelength. Surprisingly, the absorption wavelength is highly sensitive to\nchanges in the dot diameter, but almost insensitive to changes in the dot\nheight. This unpredicted behavior is explained by sensitivity analysis of\ndifferent factors which affect the optical transition energy.",
        "positive": "Strain control of exciton and trion spin-valley dynamics in monolayer\n  transition metal dichalcogenides: The electron-hole exchange interaction is a fundamental mechanism that drives\nvalley depolarization via intervalley exciton hopping in semiconductor\nmulti-valley systems. Here, we report polarization-resolved photoluminescence\nspectroscopy of neutral excitons and negatively charged trions in monolayer\nMoSe$_2$ and WSe$_2$ under biaxial strain. We observe a marked\nenhancement(reduction) on the WSe$_2$ triplet trion valley polarization with\ncompressive(tensile) strain while the trion in MoSe$_2$ is unaffected. The\norigin of this effect is shown to be a strain dependent tuning of the\nelectron-hole exchange interaction. A combined analysis of the strain dependent\npolarization degree using ab initio calculations and rate equations shows that\nstrain affects intervalley scattering beyond what is expected from strain\ndependent bandgap modulations. The results evidence how strain can be used to\ntune valley physics in energetically degenerate multi-valley systems."
    },
    {
        "anchor": "Renormalization and cyclotron resonance in bilayer graphene with weak\n  electron-hole asymmetry: Cyclotron resonance in bilayer graphene is studied with weak electron-hole\nasymmetry, suggested by experiment, taken into account and with the focus on\nmany-body corrections that evade Kohn's theorem. It is shown by direct\ncalculation that the theory remains renormalizable to O(e^2) in the presence of\nelectron-hole asymmetry parameters, and a general program to carry out\nrenormalization for graphene under a magnetic field is presented. Inclusion of\nelectron-hole asymmetry in part improves the theoretical fit to the existing\ndata and the data appear to indicate the running of the renormalized velocity\nfactor with the magnetic field, which is a key consequence of renormalization.",
        "positive": "Holographic Entanglement Renormalization of Topological Insulators: We study the real-space entanglement renormalization group flows of\ntopological band insulators in (2+1) dimensions by using the continuum\nmulti-scale entanglement renormalization ansatz (cMERA). Given the ground state\nof a Chern insulator, we construct and study its cMERA by paying attention, in\nparticular, to how the bulk holographic geometry and the Berry curvature depend\non the topological properties of the ground state. It is found that each state\ndefined at different energy scale of cMERA carries a nonzero Berry flux, which\nis emanated from the UV layer of cMERA, and flows towards the IR. Hence, a\ntopologically nontrivial UV state flows under the RG to an IR state, which is\nalso topologically nontrivial. On the other hand, we found that there is an\nobstruction to construct the exact ground state of a topological insulator with\na topologically trivial IR state. I.e., if we try to construct a cMERA for the\nground state of a Chern insulator by taking a topologically trivial IR state,\nthe resulting cMERA does not faithfully reproduce the exact ground state at all\nlength scales."
    },
    {
        "anchor": "Ballistic correction to the density of states in an interacting\n  three-dimensional metal: We study the tunneling density of states (DOS) in an interacting disordered\nthree-dimensional metal and calculate its energy dependence in the\nquasiballistic regime, for the deviation from the Fermi energy, $E-E_F$,\nexceeding the elastic scattering rate. In this region, the DOS correction\noriginates from the interplay of the interaction and single-impurity\nscattering. Depending on the distance between the interaction point and the\nimpurity, one should distinguish (i) the smallest scales of the order of the\nFermi wavelength and (ii) larger spatial scales of the order of $\\hbar\nv_F/|E-E_F|$, where $v_F$ is the Fermi velocity. In two dimensions, the\nlarge-scale contribution prevails, resulting in a nearly universal DOS\ncorrection. The peculiarity of Friedel oscillations in three dimensions is that\nthe contributions from small and large scales are typically comparable, making\nthe DOS correction sensitive to the details of the interaction and\ndemonstrating a significant particle-hole asymmetry. On the other hand, we show\nthat the non-analytic part of the DOS is determined by large scales and can be\nexpressed in terms of the Fermi-surface characteristics only.",
        "positive": "Thermopower in hBN/graphene/hBN superlattices: Thermoelectric effects are highly sensitive to the asymmetry in the density\nof states around the Fermi energy and can be exploited as probes of the\nelectronic structure. We experimentally study thermopower in high-quality\nmonolayer graphene, within heterostructures consisting of complete hBN\nencapsulation and 1D edge contacts, where the graphene and hBN lattices are\naligned. When graphene is aligned to one of the hBN layers, we demonstrate the\npresence of additional sign reversals in the thermopower as a function of\ncarrier density, directly evidencing the presence of the moir\\'e superlattice.\nWe show that the temperature dependence of the thermopower enables the\nassessment of the role of built-in strain variation and van Hove singularities\nand hints at the presence of Umklapp electron-electron scattering processes. As\nthe thermopower peaks around the neutrality point, this allows to probe the\nenergy spectrum degeneracy. Further, when graphene is double-aligned with the\ntop and bottom hBN crystals, the thermopower exhibits features evidencing\nmultiple cloned Dirac points caused by the differential super-moir\\'e lattice.\nFor both cases we evaluate how well the thermopower agrees with Mott's\nequation. Finally, we show the same superlattice device can exhibit a\ntemperature-driven thermopower reversal from positive to negative and vice\nversa, by controlling the carrier density. The study of thermopower provides an\nalternative approach to study the electronic structure of 2D superlattices,\nwhilst offering opportunities to engineer the thermoelectric response on these\nheterostructures."
    },
    {
        "anchor": "Rings sliding on a honeycomb network: Adsorption contours, interactions,\n  and assembly of benzene on Cu(111): Using a van der Waals density functional (vdW-DF) [Phys. Rev. Lett. 92,\n246401 (2004)], we perform ab initio calculations for the adsorption energy of\nbenzene (Bz) on Cu(111) as a function of lateral position and height. We find\nthat the vdW-DF inclusion of nonlocal correlations (responsible for dispersive\ninteractions) changes the relative stability of eight binding-position options\nand increases the binding energy by over an order of magnitude, achieving good\nagreement with experiment. The admolecules can move almost freely along a\nhoneycomb web of \"corridors\" passing between fcc and hcp hollow sites via\nbridge sites. Our diffusion barriers (for dilute and two condensed adsorbate\nphases) are consistent with experimental observations. Further vdW-DF\ncalculations suggest that the more compact (hexagonal) Bz-overlayer phase, with\nlattice constant a = 6.74 \\AA, is due to direct Bz-Bz vdW attraction, which\nextends to ~8 \\AA. We attribute the second, sparser hexagonal Bz phase, with a\n= 10.24 \\AA, to indirect electronic interactions mediated by the metallic\nsurface state on Cu(111). To support this claim, we use a formal\nHarris-functional approach to evaluate nonperturbationally the asymptotic form\nof this indirect interaction. Thus, we can account well for benzene\nself-organization on Cu(111).",
        "positive": "Mesoscopic Behavior Near a Two-Dimensional Metal-Insulator Transition: We study conductance fluctuations in a two-dimensional electron gas as a\nfunction of chemical potential (or gate voltage) from the strongly insulating\nto the metallic regime. Power spectra of the fluctuations decay with two\ndistinct exponents (1/v_l and 1/v_h). For conductivity $\\sigma\\sim 0.1\ne^{2}/h$, we find a third exponent (1/v_i) in the shortest samples, and\nnon-monotonic dependence of v_i and v_l on \\sigma. We study the dependence of\nv_i, v_l, v_h, and the variances of corresponding fluctuations on \\sigma,\nsample size, and temperature. The anomalies near $\\sigma\\simeq 0.1 e^{2}/h$\nindicate that the dielectric response and screening length are critically\nbehaved, i.e. that Coulomb correlations dominate the physics."
    },
    {
        "anchor": "Memristive control of plasmon-mediated nonlinear photoluminescence in Au\n  nanowires: Nonlinear photoluminescence (N-PL) is a broadband photon emission arising\nfrom non-equilibrium electron distribution generated at the surface of metallic\nnanostructures by an ultrafast pulsed laser illumination. N-PL is sensitive to\nsurface morphology, local electromagnetic field strength, and electronic band\nstructure making it relevant to probe optically excited nanoscale plasmonic\nsystems. It also has been key to access the complex multiscale time dynamics\nruling electron thermalization. Here, we show that the surface plasmons\nmediated N-PL emitted by a gold nanowire can be modified by an electrical\narchitecture featuring a nanogap. Upon voltage activation, we observe that N-PL\nbecomes dependent to the electrical transport dynamics and can thus be locally\nmodulated. This finding brings an electrical leverage to externally control the\nphotoluminescence generated from metal nanostructures, and constitutes an asset\nfor the development of emerging nanoscale interface devices managing photons\nand electrons.",
        "positive": "Singular conductance of a spin 1 quantum dot: We interpret the recent observation of a zero-bias anomaly in spin-1 quantum\ndots in terms of an underscreened Kondo effect. Although a spin-1 quantum dots\nare expected to undergo a two-stage quenching effect, in practice the log\nnormal distribution of Kondo temperatures leads to a broad temperature region\ndominated by underscreened Kondo physics. General arguments, based on the\nasymptotic decoupling between the partially screened moment and the leads,\npredict a singular temperature and voltage dependence of the conductance $G$\nand differential conductance $g$, resulting in $dg/dT\\sim 1/T$ and $dG/dV \\sim\n1/V$. Using a Schwinger boson approach, we show how these qualitative\nexpectations are borne out in a detailed many body calculation."
    },
    {
        "anchor": "Phosphorene: A New 2D Material with High Carrier Mobility: Preceding the current interest in layered materials for electronic\napplications, research in the 1960's found that black phosphorus combines high\ncarrier mobility with a fundamental band gap. We introduce its counterpart,\ndubbed few-layer phosphorene, as a new 2D p-type material. Same as graphene and\nMoS2, phosphorene is flexible and can be mechanically exfoliated. We find\nphosphorene to be stable and, unlike graphene, to have an inherent, direct and\nappreciable band-gap that depends on the number of layers. Our transport\nstudies indicate a carrier mobility that reflects its structural anisotropy and\nis superior to MoS2. At room temperature, our phosphorene field-effect\ntransistors with 1.0 um channel length display a high on-current of 194 mA/mm,\na high hole field-effect mobility of 286 cm2/Vs, and an on/off ratio up to 1E4.\nWe demonstrate the possibility of phosphorene integration by constructing the\nfirst 2D CMOS inverter of phosphorene PMOS and MoS2 NMOS transistors.",
        "positive": "Quantum oscillations and three-dimensional quantum Hall effect in\n  ZrTe$_5$: Recent experiments have reported a lot of spectacular transport properties in\ntopological materials, such as quantum oscillations and three-dimensional (3D)\nquantum Hall effect (QHE) in ZrTe$_5$. In this paper, by using a strong\ntopological insulator model to describe ZrTe$_5$, we study the magnetotransport\nproperty of the 3D system. With fixed carrier density, we find that there\nexists a deferring effect in the chemical potential, which favors\ndistinguishing the saddle points of the inverted LLs. On the other hand, with\nfixed chemical potential, the features of 3D QHE are demonstrated and we\nattribute the underlying mechanisms to the interplay between Dirac fermions,\nmagnetic field and impurity scatterings."
    },
    {
        "anchor": "Chirality driven topological electronic structure of DNA-like materials: Topological aspects of the geometry of DNA and similar chiral molecules have\nreceived a lot of attention, while the topology of their electronic structure\nis less explored. Previous experiments have revealed that DNA can efficiently\nfilter spin-polarized electrons between metal contacts, a process called\nchiral-induced spin-selectivity (CISS). However, the underlying correlation\nbetween chiral structure and electronic spin remains elusive. In this work, we\nreveal an orbital texture in the band structure, a topological characteristic\ninduced by the chirality. We find that this orbital texture enables the chiral\nmolecule to polarize the quantum orbital. This orbital polarization effect\n(OPE) induces spin polarization assisted by the spin-orbit interaction from a\nmetal contact and leads to magnetorestistance and chiral separation. The\norbital angular momentum of photoelectrons also plays an essential role in\nrelated photoemission experiments. Beyond CISS, we predict that OPE can induce\nspin-selective phenomena even in achiral but inversion-breaking materials.",
        "positive": "Long distance coupling of resonant exchange qubits: We investigate the effectiveness of a microwave cavity as a mediator of\ninteractions between two resonant exchange (RX) qubits in semiconductor quantum\ndots (QDs) over long distances, limited only by the extension of the cavity.\nOur interaction model includes the orthonormalized Wannier orbitals constructed\nfrom Fock-Darwin states under the assumption of a harmonic QD confinement\npotential. We calculate the qubit-cavity coupling strength in a Jaynes Cummings\nHamiltonian, and find that dipole transitions between two states with an\nasymmetric charge configuration constitute the relevant RX quoit-cavity\ncoupling mechanism. The effective coupling between two RX qubits in a shared\ncavity yields a universal two-qubit iSWAP-gate with gate times on the order of\nnanoseconds over distances on the order of up to a millimeter."
    },
    {
        "anchor": "Polarized emission of CdSe nanocrystals in magnetic field: the role of\n  phonon-assisted recombination of the dark exciton: The recombination dynamics and spin polarization of excitons in CdSe\nnanocrystals synthesized in a glass matrix are investigated using polarized\nphotoluminescence in high magnetic fields up to 30 Tesla. The dynamics are\naccelerated by increasing temperature and magnetic field, confirming the dark\nexciton nature of the low-temperature photoluminescence (PL). The circularly\npolarized PL in magnetic fields reveals several unusual appearances: (i) a\nspectral dependence of the polarization degree, (ii) its low saturation value,\nand (iii) a stronger intensity of the Zeeman component which is higher in\nenergy. The latter feature is the most surprising being in contradiction with\nthe thermal population of the exciton spin sublevels. The same contradiction\nwas previously observed in the ensemble of wet-chemically synthesized CdSe\nnanocrystals, but was not understood. We present a theory which explains all\nthe observed features and shows that the inverted ordering of the circular\npolarized PL maxima from the ensemble of nanocrystals is a result of\ncompetition between the zero phonon (ZPL) and one optical phonon (1PL) assisted\nemission of the dark excitons. The essential aspects of the theoretical model\nare different polarization properties of the dark exciton emission via ZPL and\n1PL recombination channels and the inhomogeneous broadening of the PL spectrum\nfrom the ensemble of nanocrystals exceeding the optical phonon energy.",
        "positive": "Electron-Phonon Coupling on the Surface of Topological Insulators: Topological insulators (TIs) are materials that have a bulk electronic band\ngap like an ordinary insulator but have protected conducting states on their\nsurface. One of the most interesting properties of TIs is their spin helicity,\nwhereby the spin is locked normal to the wave vector of the surface electronic\nstate. The topological surface states should be very stable in TIs, since these\nspin-textured surface states are robust against spin-independent\nbackscattering. Scattering from defects and other lattice imperfections is\npossible provided the spin is not completely flipped. However, the quality of\nTI crystals can be controlled by careful growth, whereas phonons will exist in\neven the most perfect crystals. Consequently, electron-phonon coupling (EPC)\nshould be the dominant scattering mechanism for surface electronic states at\nfinite temperatures. Hence, the study of EPC in TIs is of exceptional\nimportance in assessing any potential applications. In this article both\nexperimental and theoretical studies of the EPC on the surface of TIs are\nreviewed, with the contents mainly focused on the typical strong three\ndimensional TIs, such as Bi2Se3 and Bi2Te3."
    },
    {
        "anchor": "Phase Resolved Surface Plasmon Interferometry of Graphene: The surface plasmon polaritons (SPP) of graphene reflect the microscopic\nspatial variations of underlying electronic structure and dynamics. Access to\nthis information requires probing the full SPP response function. We image the\ngraphene SPP phase and amplitude by combining scanning probe tip coupled\nsurface plasmon interferometry with phase resolved near-field signal detection.\nWe show that a simple analytical cavity model can self-consistently describe\nthe phase and amplitude response both for edge, grain boundary, and defect SPP\nreflection and scattering. The derived complex SPP wavevector, damping, and\ncarrier mobility agree with the results from more complex models. This phase\ninformation opens a new degree of freedom for spatial and spectral graphene SPP\ntuning and modulation for opto-electronics applications.",
        "positive": "Weak Localization and Electron-electron Interactions in Few Layer Black\n  Phosphorus Devices: Few layer phosphorene(FLP) devices are extensively studied due to its unique\nelectronic properties and potential applications on nano-electronics . Here we\npresent magnetotransport studies which reveal electron-electron interactions as\nthe dominant scattering mechanism in hexagonal boron nitride-encapsulated FLP\ndevices. From weak localization measurements, we estimate the electron\ndephasing length to be 30 to 100 nm at low temperatures, which exhibits a\nstrong dependence on carrier density n and a power-law dependence on\ntemperature (~T-0.4). These results establish that the dominant scattering\nmechanism in FLP is electron-electron interactions."
    },
    {
        "anchor": "Negative transverse magnetoresistance due to negative off-diagonal mass\n  in linear dispersion materials: This study calculated the magnetoresistance (MR) in the Dirac electron\nsystem, Dressellhaus-Kip-Kittel (DKK) model, and nodal-line semimetals based on\nthe semiclassical Boltzmann theory, with particular focus on the detailed\nenergy dispersion structure. The negative off-diagonal effective-mass was found\nto induce negative transverse MR owing to the energy dispersion effect. The\nimpact of the off-diagonal mass was more prominent in case of a linear energy\ndispersion. Further, Dirac electron systems could realize negative MR even if\nthe Fermi surface was perfectly spherical. The obtained negative MR in the DKK\nmodel may explain the long-standing mystery in p-type Si.",
        "positive": "Quantum dots in magnetic fields: Phase diagram and broken symmetry of\n  the Chamon-Wen edge: Quantum dots in magnetic fields are studied within the current spin density\nfunctional formalism avoiding any spatial symmetry restrictions of the\nsolutions. We find that the maximum density droplet reconstructs into states\nwith broken internal symmetry: The Chamon-Wen edge co-exists with a modulation\nof the charge density along the edge. The phase boundaries between the\npolarization transition, the maximum density droplet and its reconstruction are\nin agreement with recent experimental results."
    },
    {
        "anchor": "Realizing Topological Superconductivity with Superlattices: The realization of topological superconductors (SCs) in one or two dimensions\nis a highly pursued goal. Prominent proposed realization schemes include\nsemiconductor/superconductor heterostructures and set stringent constraints on\nthe chemical potential of the system. However, the ability to keep the chemical\npotential in the required range while in the presence of an adjacent SC and its\naccompanied screening effects, is a great experimental challenge. In this work,\nwe study a SC lattice structure in which the SC is deposited periodically on a\none- or two-dimensional sample. We demonstrate that this realization platform\novercomes the challenge of controlling the chemical potential in the presence\nof the superconductor's electrostatic screening. We show how Majorana bound\nstates emerge at the ends of a one-dimensional system proximity coupled to a\none-dimensional SC lattice, and move on to present a SC-lattice-based\nrealization of the two-dimensional px+ipy SC, hosting chiral Majorana modes at\nits edges. In particular, we establish that even when assuming the worst case\nof absolute screening, in which the chemical potential under the SC is\ncompletely unaffected by the external gate potential, the topological phase can\nbe reached by tuning the chemical potential in the area not covered by the SC.\nFinally, we briefly discuss possible effects of Coulomb blockade on the\nproperties of the system.",
        "positive": "Interaction effects in 2D electron gas in a random magnetic field:\n  Implications for composite fermions and quantum critical point: We consider a clean two-dimensional interacting electron gas subject to a\nrandom perpendicular magnetic field, h({\\bf r}). The field is nonquantizing, in\nthe sense, that {\\cal N}_h-a typical flux into the area \\lambda_{\\text{\\tiny\nF}}^2 in the units of the flux quantum (\\lambda_{\\text{\\tiny F}} is the de\nBroglie wavelength) is small, {\\cal N}_h\\ll 1. If the spacial scale, \\xi, of\nchange of h({\\bf r}) is much larger than \\lambda_{\\text{\\tiny F}}, the\nelectrons move along semiclassical trajectories. We demonstrate that a weak\nfield-induced curving of the trajectories affects the interaction-induced\nelectron lifetime in a singular fashion: it gives rise to the correction to the\nlifetime with a very sharp energy dependence. The correction persists within\nthe interval \\omega \\sim \\omega_0= E_{\\text{\\tiny F}}{\\cal N}_h^{2/3} much\nsmaller than the Fermi energy, E_{\\text{\\tiny F}}. It emerges in the third\norder in the interaction strength; the underlying physics is that a small phase\nvolume \\sim (\\omega/E_{\\text{\\tiny F}})^{1/2} for scattering processes,\ninvolving {\\em two} electron-hole pairs, is suppressed by curving. Even more\nsurprising effect that we find is that {\\em disorder-averaged} interaction\ncorrection to the density of states, \\delta\\nu(\\omega), exhibits {\\em\noscillatory} behavior, periodic in \\bigl(\\omega/\\omega_0\\bigr)^{3/2}. In our\ncalculations of interaction corrections random field is incorporated via the\nphases of the Green functions in the coordinate space. We discuss the relevance\nof the new low-energy scale for realizations of a smooth random field in\ncomposite fermions and in disordered phase of spin-fermion model of\nferromagnetic quantum criticality."
    },
    {
        "anchor": "Observability of cyclotron resonance in the hydrodynamic regime of\n  bilayer graphene: We offer theoretical predictions for the frequency of the resonant frequency\nof transport for the hydrodynamic description of bilayer graphene, as well as\nprovide quantification for the relative strength of this signal throughout\nphase space. Our calculations are based on classical fluid dynamics equations\nderived from the Boltzmann equation for bilayer graphene in arXiv:1901.07039,\nand suggest that while this resonance is accessible to current experimental\ntechniques, the same mechanism which causes the hydrodynamic resonance to\ndiffer from the Fermi liquid value is responsible for a significant broadening\nof the peak.",
        "positive": "Quantum Measurement of Phonon Shot Noise: We provide a full quantum mechanical analysis of a weak energy measurement of\na driven mechanical resonator. We demonstrate that measurements too weak to\nresolve individual mechanical Fock states can nonetheless be used to\nunambiguously detect the non-classical energy fluctuations of the driven\nmechanical resonator, i.e. \"phonon shot noise\". We also show that the third\nmoment of the oscillator's energy fluctuations provides a far more sensitive\nprobe of quantum effects than the second moment, and that measuring the third\nmoment via the phase shift of light in an optomechanical setup directly yields\nthe type of operator ordering postulated in the theory of full-counting\nstatistics."
    },
    {
        "anchor": "Spin transport in interacting quantum wires and carbon nanotubes: We present a general formulation of spin-dependent transport through a clean\none-dimensional interacting quantum wire or carbon nanotube, connected to\nnon-collinear ferromagnets via tunnel junctions. We show that the low energy\ndescription of each junction is given by a conformally-invariant boundary\ncondition representing *exchange coupling*, in addition to a pair of electron\ntunneling operators. The effects of the exchange coupling are strongly enhanced\nby interactions, leading to a dramatic suppression of spin accumulation. This\nis a direct signature of spin-charge separation in a Luttinger liquid.\nFurthermore, we demonstrate that magnetic polarization can lead to oscillations\nin the non-linear current-voltage relation. This phenomena is a surprising\npurely nonequilibrium effect due to backscattering interactions, which are thus\ndangerously marginally irrelevant in the repulsively-interacting Luttinger\nliquid.",
        "positive": "Trivial and inverted Dirac bands, and emergence of quantum spin Hall\n  states in graphene on transition-metal dichalcogenides: Proximity orbital and spin-orbital effects of graphene on monolayer\ntransition-metal dichalcogenides (TMDCs) are investigated from\nfirst-principles. The Dirac band structure of graphene is found to lie within\nthe semiconducting gap of TMDCs for sulfides and selenides, while it merges\nwith the valence band for tellurides. In the former case the proximity-induced\nstaggered potential gaps and spin-orbit couplings (all on the meV scale) of the\nDirac electrons are established by fitting to a phenomenological effective\nHamiltonian. While graphene on MoS$_2$, MoSe$_2$, and WS$_2$ has a\ntopologically trivial band structure, graphene on WSe$_2$ exhibits inverted\nbands. Using a realistic tight-binding model we find topologically protected\nhelical edge states for graphene zigzag nanoribbons on WSe$_2$, demonstrating\nthe quantum spin Hall effect. This model also features \"half-topological\nstates\", which are protected against time-reversal disorder on one edge only."
    },
    {
        "anchor": "Microscale Motion Control Through Ferromagnetic Films: Actuation and control of motion in micro-mechanical systems are technological\nchallenges, since they are accompanied by mechanical friction and wear,\nprincipal and well known sources of device lifetime reduction. In this\ntheoretical work we propose a non-contact motion control technique based on the\nintroduction of a tunable magnetic interaction. The latter is realized by\ncoating two non-touching sliding bodies with ferromagnetic films. The resulting\ndynamics is determined by shape, size and ordering of magnetic domains arising\nin the films below the Curie temperature. We demonstrate that the domain\nbehavior can be tailored by acting on handles like ferromagnetic coating\npreparation, external magnetic fields and the finite distance between the\nplates. In this way, motion control can be achieved without mechanical contact.\nMoreover, we discuss how such handles can disclose a variety of sliding\nregimes. Finally, we propose how to practically implement the proposed model\nsliding system.",
        "positive": "Optical properties of helical edge channels in zinc-blende-type\n  topological insulators: Selection rules, circular and linear dichroism,\n  circular and linear photocurrents: We develop a theory of electron-photon interaction for helical edge channels\nin two-dimensional topological insulators based on zinc-blende-type quantum\nwells. It is shown that the lack of space inversion symmetry in such structures\nenables the electro-dipole optical transitions between the spin branches of the\ntopological edge states. Further, we demonstrate the linear and circular\ndichroism associated with the edge states and the generation of edge\nphotocurrents controlled by radiation polarization."
    },
    {
        "anchor": "Two Dimensional Ir-Cluster Lattices on Moir\u00e9 of Graphene with Ir(111): Lattices of Ir clusters have been grown by vapor phase deposition on graphene\nmoir\\'{e}s on Ir(111). The clusters are highly ordered, spatially and thermally\nstable below 500K. Their narrow size distribution is tunable from 4 to about\n130 atoms. A model for cluster binding to the graphene is presented based on\nscanning tunneling microscopy and density functional theory. The proposed\nbinding mechanism suggests that similar cluster lattices might be grown of\nmaterials other than Ir.",
        "positive": "Conductance of interacting Aharonov-Bohm systems: A simple formula for the zero-temperature linear response conductance of an\ninteracting mesoscopic region, threaded by magnetic flux, and attached to\nnoninteracting single-channel leads is presented. The formula is valid for a\ngeneral interacting system exhibiting Fermi liquid properties. As an example of\nthe efficiency of the formula the results for the conductance of a simple\nAharonov-Bohm ring with Kondo-Fano resonance physics are presented and compared\nwith numerical renormalization group results."
    },
    {
        "anchor": "Tunneling gap of laterally separated quantum Hall states: We use a method of matched asymptotics to determine the energy gap of two\ncounter-propagating, strongly interacting, quantum Hall edge states. The\nmicroscopic edge state dispersion and Coulomb interactions are used to\nprecisely constrain the short-distance behavior of an integrable field theory,\nwhich then determines the low energy spectrum. We discuss the relationship of\nour results to the tunneling measurements of Kang et al., Nature 403, 59\n(2000).",
        "positive": "Novel substrates for Helium adsorption: Graphane and Graphene-Fluoride: The discovery of fullerenes has stimulated extensive exploration of the\nresulting behavior of adsorbed films. Our study addresses the planar substrates\ngraphene-fluoride (GF) and graphane (GH) in comparison to graphene. We present\ninitial results concerning the potential energy, energy bands and low density\nbehavior of 4He and 3He films on such different surfaces. For example, while\ngraphene presents an adsorption potential that is qualitatively similar to that\non graphite, GF and GH yield potentials with different symmetry, a number of\nadsorption sites double that on graphene/graphite and a larger corrugation for\nthe adatom. In the case of GF, the lowest energy band width is similar to that\non graphite but the He atom has a significantly larger effective mass and the\nadsorption energy is about three time that on graphite. Implications concerning\nthe monolayer phase diagram of 4He are explored with the exact path integral\nground state method. A commensurate ordered state similar to the sqrt{3} x\nsqrt{3} R30^o state on graphite is found the be unstable both on GF and on GH.\nThe ground states of submonolayer 4He on both GF and GH are superfluids with a\nBose Einstein condensate fraction of about 10%."
    },
    {
        "anchor": "Revision of the edge channel picture for the integer quantum Hall effect: State of the art computing opens now a new window to the integer quantum Hall\neffect (IQHE) regime, which enforces a major revision of the common knowledge\naccumulated so far. In our record-breaking application of the Hartree-Fock\nmethod we use up to 3000 electrons distributed over up to 5000 states for\nalmost macroscopic system size of 1000x1000nm. In particular, the formation of\ncompressible and in-compressible edge stripes turns out to develop essentially\ndifferent from the common picture used so far. Oppositely to the theory of\nChklovskii, Shklovskii and Glazman (CSG), the narrow channels, as assumed by\nthe early models of the IQHE, do not widen up into wide compressible stripes.\nInstead, the wide compressible stripes of CSG transform into a mixture of\nclusters of full and empty spin-split LLs, while the cluster boundaries create\na network of still narrow quantum channels sitting on top of the wide\ncompressible stripes. On this background the early models based on narrow edge\nchannels do not suffer from neglecting electron-electron interaction as falsely\nstated in the past. Quite oppositely, in contrast to the common believe, our\nmodelling demonstrates that also the IQHE regime carries the hallmark of\nmany-body physics which stabilizes narrow edge channels also in the presence of\nelectron-electron interaction.",
        "positive": "Composite fermion theory of rapidly rotating two-dimensional bosons: Ultracold neutral bosons in a rapidly rotating atomic trap have been\npredicted to exhibit fractional quantum Hall-like states. We describe how the\ncomposite fermion theory, used in the description of the fractional quantum\nHall effect for electrons, can be applied to interacting bosons. Numerical\nevidence supporting the formation of composite fermions, each being the bound\nstate of a boson and one flux quantum, is shown for filling fractions of the\ntype nu=p/(p+1), both by spectral analysis and by direct comparison with trial\nwave functions. The rapidly rotating system of two-dimensional bosons thus\nconstitutes an interesting example of \"statistical transmutation,\" with bosons\nbehaving like composite fermions. We also describe the difference between the\nelectronic and the bosonic cases when p approaches infinity. Residual\ninteractions between composite fermions are attractive in this limit, resulting\nin a paired composite-fermion state described by the Moore-Read wave function."
    },
    {
        "anchor": "Tomonaga-Luttinger liquid with reservoirs in a multi-terminal geometry: We propose a formalism which uses boundary conditions imposed on the\nLuttinger liquid (LL) to describe the transport properties of a LL coupled to\nreservoirs. The various boundary conditions completely determine linear\ntransport in the joint system reservoirs+LL. As an illustration we consider an\nexactly solvable microscopic model in a multi-terminal geometry for which such\nboundary conditions can be explicitly derived; in this model the\nLandauer-B\\\"uttiker formalism fails: if it were valid, the relation between the\nconductance matrix elements and the reflection and transmission coefficients\ncould yield negative probabilities. We then apply our formalism to a discussion\nof shot noise through an impurity in a LL connected to two reservoirs.",
        "positive": "Large effect of the metal substrate on the magnetic anisotropy of Co on\n  hexagonal Boron Nitride: We combine x-ray absorption spectroscopy (XAS), x-ray magnetic circular\ndichroism (XMCD) and x-ray magnetic linear dichroism (XMLD) data with first\nprinciples density functional theory (DFT) calculations and a multiorbital many\nbody Hamiltonian approach to understand the electronic and magnetic properties\nof Co atoms adsorbed on h-BN/Ru(0001) and h-BN/Ir(111). The XAS line shape\nreveals, for both substrates, an electronic configuration close to $3d^8$,\ncorresponding to a spin $S = 1$. Magnetic field dependent XMCD data show large\n(14 meV) out-of-plane anisotropy on h-BN/Ru(0001), while it is almost isotropic\n(tens of $\\mu$eV) on h-BN/Ir(111). XMLD data together with both DFT\ncalculations and the results of the multiorbital Hubbard model suggest that the\ndissimilar magnetic anisotropy originates from different Co adsorption sites,\nnamely atop N on h-BN/Ru(0001) and 6-fold hollow on h-BN/Ir(111)."
    },
    {
        "anchor": "Signatures of Rashba Spin-Orbit Interaction in Charge and Spin\n  Properties of Quantum Hall Systems: We study the local equilibrium properties of two-dimensional electron gases\nat high magnetic fields in the presence of random smooth electrostatic\ndisorder, Rashba spin-orbit coupling, and the Zeeman interaction. Using a\nsystematic magnetic length ($l_B$) expansion within a Green's function\nframework we derive quantum functionals for the local spin-resolved particle\nand current densities which can be useful for future studies combining disorder\nand mean-field electron-electron interaction in the quantum Hall regime. We\npoint out that the spin polarization presents a peculiar spatial dependence\nwhich can be used to determine the strength of the Rashba coupling by local\nprobes. The spatial structure of the current density, consisting of both\ncompressible and incompressible contributions, also essentially reflects the\neffects of Rashba spin-orbit interaction on the energy spectrum. We show that\nin the semiclassical limit $l_B \\rightarrow 0$ the local Hall conductivity\nremains, however, still quantized in units of $e^2/h$ for any finite strength\nof the spin-orbit interaction. In contrast, it becomes half-integer quantized\nwhen the latter is infinite, a situation which corresponds to a disordered\ntopological insulator surface consisting of a single Dirac cone. Finally, we\nargue how to define at high magnetic fields a spin Hall conductivity related to\na dissipationless angular momentum flow, which is characterized by a sequence\nof plateaus as a function of the inverse magnetic field (thus free of\nresonances).",
        "positive": "A Physically based compact I-V model for monolayer TMDC channel MOSFET\n  and DMFET biosensor: In this work, a compact transport model has been developed for monolayer\ntransition metal dichalcogenide (TMDC) channel MOSFET. The analytical model\nsolves the Poisson's equation for the inversion charge density to get the\nelectrostatic potential in the channel. Current is then calculated by solving\nthe drift-diffusion equation. The model makes gradual channel approximation to\nsimplify the solution procedure. The appropriate density of states obtained\nfrom the first principle density functional theory simulation has been\nconsidered to keep the model physically accurate for monolayer TMDC channel\nFET. The outcome of the model has been benchmarked against both experimental\nand numerical quantum simulation results with the help of a few fitting\nparameters. Using the compact model, detailed output and transfer\ncharacteristics of monolayer $WSe_2$ FET have been studied, and various\nperformance parameters have been determined. The study confirms excellent ON\nand OFF state performances of monolayer $WSe_2$ FET which could be viable for\nthe next generation high-speed, low power applications. Also, the proposed\nmodel has been extended to study the operation of a biosensor. A monolayer\n$MoS_2$ channel based dielectric modulated FET is investigated using the\ncompact model for detection of a biomolecule in a dry environment."
    },
    {
        "anchor": "Mechanical photoluminescence excitation spectra of a strongly driven\n  spin-mechanical system: We report experimental studies of a driven spin-mechanical system, in which a\nnitrogen vacancy (NV) center couples to out-of-plane vibrations of a diamond\ncantilever through the excited-state deformation potential. Photoluminescence\nexcitation studies show that in the unresolved sideband regime and under strong\nresonant mechanical driving, the excitation spectra of a NV optical transition\nfeature two spectrally sharp peaks, corresponding to the two turning points of\nthe oscillating cantilever. In the limit that the strain-induced frequency\nseparation between the two peaks far exceeds the NV zero-phonon linewidth, the\nspectral position of the individual peak becomes sensitive to minute detuning\nbetween the mechanical resonance and the external driving force. For a fixed\noptical excitation frequency near the NV transition, NV fluorescence as a\nfunction of mechanical detuning features resonances with a linewidth that can\nbe orders of magnitude smaller than the intrinsic linewidth of the mechanical\nmode. This enhanced sensitivity to mechanical detuning can potentially provide\nan effective mechanism for mechanical sensing, for example, mass sensing via\nmeasurements of induced changes in the mechanical oscillator frequency.",
        "positive": "Spin accumulation in the semi classical and quantum regimes: We consider spin accumulation at a ferromagnet--normal metal interface in the\npresence of magnetic scattering in the normal metal. In the classical regime,\nwe discuss the inverse Drude scaling of the conductance as a function of the\ninterface transparencies. We present a treatment based on an exact solution of\nthe Boltzmann equation. In the quantum regime, we solve a single impurity\n``spin-flip Fabry Perot interferometer'' for quantum coherent multiple\nscatterings, in which we find a resonance in the spin flip channels. This\nresonance appears to be the quantum analog of the semi classical inverse Drude\nscaling of the conductance."
    },
    {
        "anchor": "Magnon-Plasmon Hybridization Mediated by Spin-Orbit Interaction in\n  Magnetic Materials: We propose a mechanism for magnon-plasmon coupling and hybridization in\nferromagnetic (FM) and antiferromagnetic (AFM) systems. The electric field\nassociated with plasmon oscillations creates a non-equilibrium spin density via\nthe inverse spin galvanic effect. This plasmon-induced spin density couples to\nmagnons by an exchange interaction. The strength of magnon-plasmon coupling\ndepends on the magneto-electric susceptibility of the system and the wavevector\nat which the level repulsion is happened. This wavevector may be tuned by an\napplied magnetic field. In AFM systems, the degeneracy of two chiral magnons is\nbroken in the presence of a magnetic field, and we find two separate hybrid\nmodes for left-handed and right-handed AFM magnons. Furthermore, we show that\nmagnon-plasmon coupling in AFM systems is enhanced because of strong\nintra-sublattice spin dynamics. We argue that the recently discovered\ntwo-dimensional magnetic systems are ideal platforms to investigate proposed\nmagnon-plasmon hybrid modes.",
        "positive": "Low-temperature Benchtop-synthesis of All-inorganic Perovskite Nanowires: A facile, low-temperature precipitation-based method is utilized to\ndemonstrate the synthesis of ultra-thin and highly-uniform cesium lead bromide\nperovskite nanowires (NWs). The reactions facilitate the NWs crystalline nature\nover micron-size lengths, while they impart tailored nanowire widths that range\nfrom the quantum confinement regime (~ 7 nm) and down to 2.6 nm. This colloidal\nsynthesis approach is the first of its kind that is carried out on the\nwork-bench, without demanding chemical synthesis equipment. Importantly, the\nNWs photoluminescence is shown to become improved over time, with no tedious\npost-synthesis surface treatment requirement."
    },
    {
        "anchor": "Graphene valley filter using a line defect: With its two degenerate valleys at the Fermi level, the band structure of\ngraphene provides the opportunity to develop unconventional electronic\napplications. Herein, we show that electron and hole quasiparticles in graphene\ncan be filtered according to which valley they occupy without the need to\nintroduce confinement. The proposed valley filter is based on scattering off a\nrecently observed line defect in graphene. Quantum transport calculations show\nthat the line defect is semitransparent and that quasiparticles arriving at the\nline defect with a high angle of incidence are transmitted with a valley\npolarization near 100%.",
        "positive": "Evidence for graphene plasmons in the visible spectral range probed by\n  molecules: Graphene is considered to be plasmon active only up to the infrared based on\ncombined tight binding model and random phase approximation calculations. Here\nwe show that the optical properties of graphene as measured by ellipsometry and\nsimulated by density functional theory imply the existence of strongly\nlocalized graphene plasmons in the visible with a line width of 0.1 eV. Using\nsmall emitters that provide the high wavevectors necessary to excite graphene\nplasmons at optical frequencies we demonstrate graphene plasmon induced\nexcitation enhancement by nearly 3 orders of magnitude."
    },
    {
        "anchor": "Upper limit on nonlinear optical processes: shift current and second\n  harmonic generation in extended systems: The response functions of a material characterize its behavior under external\nstimuli, such as electromagnetic radiation. Such responses may grow linearly\nwith the amplitude of the incident radiation, as is the case of absorption, or\nmay be nonlinear. The latter category includes a diverse set of phenomena such\nas second harmonic generation (SHG), shift current, sum frequency generation,\nand excited state absorption, among others. Despite decades of research into\nnonlinear response theory, and the occasional discovery of materials with large\nnonlinear responses, there has been no systematic investigation into the\nmaximum amount of nonlinear optical response attainable in solid-state\nmaterials. In this work, we present an upper bound on the second-order response\nfunctions of materials, which controls the SHG and shift current responses. We\nshow that this bound depends on the band gap, band width, and geometrical\nproperties of the material in question. We find that Kuzyk's bound for the\nmaximum SHG of isolated molecules can be exceeded by conjugation or\ncondensation of molecules to form molecular solids, and that strongly coupled\nsystems generally have larger responses than weakly coupled or isolated ones.\nAs a proof of principle, we perform first-principles calculations of the\nresponse tensors of a wide variety of materials, finding that the materials in\nour database do not yet saturate the upper bound. This suggests that new large\nSHG and shift current materials will likely be discovered by future materials\nresearch guided by the factors mentioned in this work.",
        "positive": "Bright electrically controllable quantum-dot-molecule devices fabricated\n  by in-situ electron-beam lithography: Self-organized semiconductor quantum dots represent almost ideal two-level\nsystems, which have strong potential to applications in photonic quantum\ntechnologies. For instance, they can act as emitters in close-to-ideal quantum\nlight sources. Coupled quantum dot systems with significantly increased\nfunctionality are potentially of even stronger interest since they can be used\nto host ultra-stable singlet-triplet spin qubits for efficient spin-photon\ninterfaces and for a deterministic photonic 2D cluster-state generation. We\nrealize an advanced quantum dot molecule (QDM) device and demonstrate excellent\noptical properties. The device includes electrically controllable QDMs based on\nstacked quantum dots in a pin-diode structure. The QDMs are deterministically\nintegrated into a photonic structure with a circular Bragg grating using\nin-situ electron beam lithography. We measure a photon extraction efficiency of\nup to (24$\\pm$4)% in good agreement with numerical simulations. The coupling\ncharacter of the QDMs is clearly demonstrated by bias voltage dependent\nspectroscopy that also controls the orbital couplings of the QDMs and their\ncharge state in quantitative agreement with theory. The QDM devices show\nexcellent single-photon emission properties with a multi-photon suppression of\n$g^{(2)}(0) = (3.9 \\pm 0.5) \\cdot 10^{-3}$. These metrics make the developed\nQDM devices attractive building blocks for use in future photonic quantum\nnetworks using advanced nanophotonic hardware."
    },
    {
        "anchor": "Hamiltonian inference from dynamical excitations in confined quantum\n  magnets: Quantum-disordered models provide a versatile platform to explore the\nemergence of quantum excitations in many-body systems. The engineering of spin\nmodels at the atomic scale with scanning tunneling microscopy and the local\nimaging of excitations with electrically driven spin resonance has risen as a\npowerful strategy to image spin excitations in finite quantum spin systems.\nHere, focusing on $S=1/2$ lattices as realized by Ti in MgO, we show that\ndynamical spin excitations provide a robust strategy to infer the nature of the\nunderlying Hamiltonian. We show that finite-size interference of the dynamical\nmany-body spin excitations of a generalized long-range Heisenberg model allows\nthe underlying spin couplings to be inferred. We show that the spatial\ndistribution of local spin excitations in Ti islands and ladders directly\ncorrelates with the underlying ground state in the thermodynamic limit. Using a\nsupervised learning algorithm, we demonstrate that the different parameters of\nthe Hamiltonian can be extracted by providing the spatially and\nfrequency-dependent local excitations that can be directly measured by\nelectrically driven spin resonance with scanning tunneling microscopy. Our\nresults put forward local dynamical excitations in confined quantum spin models\nas versatile witnesses of the underlying ground state, providing an\nexperimentally robust strategy for Hamiltonian inference in complex real spin\nmodels.",
        "positive": "Origin of Bardeen-Zumino current in lattice models of Weyl semimetals: For a generic lattice Hamiltonian of the electron states in Weyl semimetals,\nwe calculate the electric charge and current densities in the first order in\nbackground electromagnetic and strain-induced pseudoelectromagnetic fields. We\nshow that the resulting expressions for the densities contain contributions of\ntwo types. The contributions of the first type coincide with those in the\nchiral kinetic theory. The contributions of the second type contain the\ninformation about the whole Brillouin zone and cannot be reproduced in the\nchiral kinetic theory. Remarkably, the latter coincide exactly with the\nBardeen-Zumino terms that are usually introduced in relativistic quantum field\ntheory in order to define the consistent anomaly. We demonstrate the\ntopological origin of the Bardeen-Zumino (or, equivalently, Chern-Simons)\ncorrections by expressing them in terms of the winding number in the lattice\nHamiltonian model."
    },
    {
        "anchor": "Single- and many-particle description of scanning tunneling spectroscopy: Scanning tunneling spectroscopy measures how a single electron with definite\nenergy propagates between a sample surface and the tip of a scanning tunneling\nmicroscope. In the simplest description, the differential conductance measured\nis interpreted as the local density of states of the sample at the tip\nposition. This picture, however, is insufficient in some cases, since\nespecially smaller molecules weakly coupled with the substrate tend to have\nstrong Coulomb interactions when an electron is inserted or removed at the\nmolecule. We present theoretical approaches to go from the non-interacting and\nsingle-particle picture to the correlated many-body regime. The methodology is\nused to understand recent experiments on finite armchair graphene nanoribbons\nand phthalocyanines. We also theoretically discuss the strongly-correlated\nmodel system of fractional quantum Hall droplets.",
        "positive": "Electronic Properties of Disordered Graphene Antidot Lattices: Regular nanoscale perforations in graphene (graphene antidot lattices, GAL)\nare known to lead to a gap in the energy spectrum, thereby paving a possible\nway towards many applications. This theoretical prediction relies on a perfect\nplacement of identical perforations, a situation not likely to occur in the\nlaboratory. Here, we present a systematic study of the effects of disorder in\nGALs. We consider both geometric and chemical disorder, and evaluate the\ndensity-of-states as well as the optical conductivity of disordered GALs. The\ntheoretical method is based on an efficient algorithm for solving the\ntime-dependent Schr{\\\"o}dinger equation in a tight-binding representation of\nthe graphene sheet [S. Yuan et al., Phys. Rev. B 82, 115448 (2010)], which\nallows us to consider GALs consisting of 6400 $\\times$ 6400 carbon atoms. The\ncentral conclusion for all kinds of disorder is that the gaps found for\npristine GALs do survive at a considerable amount of disorder, but disappear\nfor very strong disorder. Geometric disorder is more detrimental to gap\nformation than chemical disorder. The optical conductivity shows a low-energy\ntail below the pristine GAL band gap due to disorder-introduced transitions."
    },
    {
        "anchor": "Is it the boundaries or disorder that dominates electron transport in\n  semiconductor `billiards'?: Semiconductor billiards are often considered as ideal systems for studying\ndynamical chaos in the quantum mechanical limit. In the traditional picture,\nonce the electron's mean free path, as determined by the mobility, becomes\nlarger than the device, disorder is negligible and electron trajectories are\nshaped by specular reflection from the billiard walls alone. Experimental\ninsight into the electron dynamics is normally obtained by magnetoconductance\nmeasurements. A number of recent experimental studies have shown these\nmeasurements to be largely independent of the billiards exact shape, and highly\ndependent on sample-to-sample variations in disorder. In this paper, we discuss\nthese more recent findings within the full historical context of work on\nsemiconductor billiards, and offer strong evidence that small-angle scattering\nat the sub-100 nm length-scale dominates transport in these devices, with\nimportant implications for the role these devices can play for experimental\ntests of ideas in quantum chaos.",
        "positive": "Gate-tunable antiferromagnetic Chern insulator in twisted bilayer\n  transition metal dichalcogenides: A series of recent experimental works on twisted MoTe$_2$ homobilayers have\nunveiled an abundance of exotic states in this system. Valley-polarized quantum\nanomalous Hall states have been identified at hole doping of $\\nu = -1$, and\nthe fractional quantum anomalous Hall effect is observed at $\\nu = -2/3$ and\n$\\nu = -3/5$. In this work, we investigate the electronic properties of\nAA-stacked twisted bilayer MoTe$_2$ at $\\nu=-2$ by $k$-space Hartree-Fock\ncalculations. We find that the phase diagram is qualitatively similar to the\nphase diagram of a Kane-Mele-Hubbard with staggered onsite potential. A\nnoteworthy phase within the diagram is the antiferromagnetic Chern insulator,\nstabilized by the external electric field. We attribute the existence of this\nChern insulator to an antiferromagnetic instability at a topological phase\ntransition between the quantum spin hall phase and a band insulator phase. We\nhighlight that the antiferromagnetic Chern insulator phase is most evident at a\ntwist angle of approximately $4^\\circ$. Our research proposes the potential of\nrealizing a Chern insulator beyond $\\nu=-1$, and contributes fresh perspectives\non the interplay between band topology and electron-electron correlations in\nmoir\\'e superlattices."
    },
    {
        "anchor": "Regenerative Soot-VI: The excited states of neutral and ionized carbon\n  in regenerative sooting discharges: We report the mechanisms of production and the state of excitation of the\nneutral and singly charged monatomic carbon in the regenerative soot as a\nfunction of the discharge parameters in graphite hollow cathode (HC) sources.\nTwo distinctly different source configurations have been investigated.\nComparisons of the level densities of various charged states of C1 have\nidentified the regenerative properties of the C radicals in graphite HC soot.",
        "positive": "Anomalous screening of quantum impurities by a neutral environment: It is a common knowledge that an effective interaction of a quantum impurity\nwith an electromagnetic field can be screened by surrounding charge carriers,\nwhether mobile or static. Here we demonstrate that very strong, `anomalous'\nscreening can take place in the presence of a neutral, weakly-polarizable\nenvironment, due to an exchange of orbital angular momentum between the\nimpurity and the bath. Furthermore, we show that it is possible to generalize\nall phenomena related to isolated impurities in an external field to the case\nwhen a many-body environment is present, by casting the problem in terms of the\nangulon quasiparticle. As a result, the relevant observables such as the\neffective Rabi frequency, geometric phase, and impurity spatial alignment are\nstraightforward to evaluate in terms of a single parameter: the\nangular-momentum-dependent screening factor."
    },
    {
        "anchor": "Observation of topological Faraday and Kerr rotations in quantum\n  anomalous Hall state by terahertz magneto-optics: Electrodynamic responses from three-dimensional (3D) topological insulators\n(TIs) are characterized by the universal magnetoelectric $E\\cdot B$ term\nconstituent of the Lagrangian formalism. The quantized magnetoelectric\ncoupling, which is generally referred to as topological magnetoelectric (TME)\neffect, has been predicted to induce exotic phenomena including the universal\nlow-energy magneto-optical effects. Here we report the experimental\ndemonstration of the long-sought TME effect, which is exemplified by\nmagneto-optical Faraday and Kerr rotations in the quantum anomalous Hall (QAH)\nstates of magnetic TI surfaces by terahertz magneto-optics. The universal\nrelation composed of the observed Faraday and Kerr rotation angles but not of\nany material parameters (e.g. dielectric constant and magnetic susceptibility)\nwell exhibits the trajectory toward the fine structure constant $\\alpha$ $(=\n2\\pi e^2/hc \\sim 1/137)$ in the quantized limit. Our result will pave a way for\nversatile TME effects with emergent topological functions.",
        "positive": "Effect of short- and long-range scattering in the conductivity of\n  graphene: Boltzmann approach vs tight-binding calculations: We present a comparative study of the density dependence of the conductivity\nof graphene sheets calculated in the tight-binding (TB) Landauer approach and\non the basis of the Boltzmann theory. The TB calculations are found to give the\nsame density dependence of the conductivity, $\\sigma \\sim n$, for short-range\nand long-range Gaussian scatterers. In the case of short-range scattering the\nTB calculations are in agreement with the predictions of the Boltzmann theory\ngoing beyond the Born approximation, but in qualitative and quantitative\ndisagreement with the standard Boltzmann approach within the Born\napproximation, predicting $\\sigma= $ const. Even for the long-range Gaussian\npotential in a parameter range corresponding to realistic systems the standard\nBoltzmann predictions are in quantitative and qualitative disagreement with the\nTB results. This questions the applicability of the standard Boltzmann approach\nwithin the Born approximation, commonly used for the interpretation of the\nresults of experimental studies of the transport in graphene."
    },
    {
        "anchor": "Field-Effect Josephson Diode via Asymmetric Spin-momentum-locking States: Recent breakthroughs in Josephson diodes dangle the possibility of extending\nconventional non-reciprocal electronics into the realm of superconductivity.\nWhile a strong magnetic field is recognized for enhancing diode efficiency, it\nconcurrently poses a risk of undermining the essential superconductivity\nrequired for non-dissipative devices. To circumvent the need for magnetic-based\ntuning, we propose a field-effect Josephson diode based on the electrostatic\ngate control of finite momentum Cooper pairs in asymmetric\nspin-momentum-locking states. We propose two possible implementations of our\ngate-controlled mechanism: (i) a topological field-effect Josephson diode in\ntime-reversal-broken quantum spin Hall insulators; and (ii) semiconductor-based\nfield-effect Josephson diodes attainable in current experimental setups\ninvolving a Zeeman field and spin-orbit coupling. Notably, the diode efficiency\nis highly enhanced in the topological field-effect Josephson diode because the\ncurrent carried by the asymmetric helical edge states is topologically\nprotected and can be tuned by local gates. In the proposed Josephson diode, the\ncombination of gates and asymmetric spin-momentum-locking nature is equivalent\nto that of a magnetic field, thus providing an alternative electrical operation\nin designing nonreciprocal superconducting devices.",
        "positive": "Resonant edge-site pumping of polaritonic Su-Schrieffer-Heeger lattices: We have theoretically investigated Su-Schrieffer-Heeger chains modelled as\noptical lattices (OL) loaded with exciton-polaritons. The chains have been\nsubject to the resonant pumping of the edge site and shaken in either adiabatic\nor high-frequency regime. The topological state has been controlled by the\nrelative phases of the lasers constructing the OL. The dynamic problem of the\noccupation of the lattice sites and eigenstates has been semi-classically\nsolved. Finally, the analysis of the occupation numbers evolution has revealed\nthat gapless, topologically trivial and non-trivial chain configurations\ndemonstrate perceptible behaviour from both qualitative (occupation pattern)\nand quantitative (total occupation) points of view."
    },
    {
        "anchor": "Light emission, light detection and strain sensing with nanocrystalline\n  graphene: Graphene is of increasing interest for optoelectronic applications exploiting\nlight detection, light emission and light modulation. Intrinsically light\nmatter interaction in graphene is of a broadband type. However by integrating\ngraphene into optical micro cavities also narrow band light emitters and\ndetectors have been demonstrated. The devices benefit from the transparency,\nconductivity and processability of the atomically thin material. To this end we\nexplore in this work the feasibility of replacing graphene by nanocrystalline\ngraphene, a material which can be grown on dielectric surfaces without catalyst\nby graphitization of polymeric films. We have studied the formation of\nnanocrystalline graphene on various substrates and under different\ngraphitization conditions. The samples were characterized by resistance,\noptical transmission, Raman, X-ray photoelectron spectroscopy, atomic force\nmicroscopy and electron microscopy measurements. The conducting and transparent\nwafer-scale material with nanometer grain size was also patterned and\nintegrated into devices for studying light-matter interaction. The measurements\nshow that nanocrystalline graphene can be exploited as an incandescent emitter\nand bolometric detector similar to crystalline graphene. Moreover the material\nexhibits piezoresistive behavior which makes nanocrystalline graphene\ninteresting for transparent strain sensors.",
        "positive": "Magnetic field imaging with NV ensembles: We demonstrate a method of imaging spatially varying magnetic fields using a\nthin layer of nitrogen-vacancy (NV) centers at the surface of a diamond chip.\nFluorescence emitted by the two-dimensional NV ensemble is detected by a CCD\narray, from which a vector magnetic field pattern is reconstructed. As a\ndemonstration, AC current is passed through wires placed on the diamond chip\nsurface, and the resulting AC magnetic field patterns are imaged using an\necho-based technique with sub-micron resolution over a 140 \\mu m x 140 \\mu m\nfield of view, giving single-pixel sensitivity ~100 nT/\\sqrt{Hz}. We discuss\nongoing efforts to further improve sensitivity and potential bioimaging\napplications such as real-time imaging of activity in functional, cultured\nnetworks of neurons."
    },
    {
        "anchor": "Enhanced photoenergy harvesting and extreme Thomson effect in\n  hydrodynamic electronic systems: The thermoelectric (TE) properties of a material are dramatically altered\nwhen electron-electron interactions become the dominant scattering mechanism.\nIn the degenerate hydrodynamic regime, the thermal conductivity is reduced and\nbecomes a {\\it decreasing} function of the electronic temperature, due to a\nviolation of the Wiedemann-Franz (WF) law. We here show how this peculiar\ntemperature dependence gives rise to new striking TE phenomena. These include\nan 80-fold increase in TE efficiency compared to the WF regime, dramatic\nqualitative changes in the steady state temperature profile, and an anomalously\nlarge Thomson effect. In graphene, which we pay special attention to here,\nthese effects are further amplified due to a doubling of the thermopower.",
        "positive": "Electric polarization and magnetization in metals: A feature of the \"modern theory\" is that electric polarization is not\nwell-defined in a metallic ground state. A different approach invokes the\ngeneral existence of a complete set of exponentially localized Wannier\nfunctions, with respect to which general definitions of microscopic electronic\npolarization and magnetization fields, and free charge and current densities\nare always admitted. These definitions assume no particular initial electronic\nstate of the crystal, and the set of microscopic fields satisfy the usual\nrelations of classical electrodynamics. Notably, when applied to a trivial\ninsulator initially occupying its $T=0$ ground state, the expressions for the\nunperturbed polarization and orbital magnetization, and for the orbital\nmagnetoelectric polarizability tensor obtained from these different approaches\ncan agree. However, the \"modern theory of magnetization\" has been extended via\nthermodynamic arguments to include metals and Chern insulators. We here compare\nwith that generalization and find disagreement; the manner in which the\nexpressions differ elucidates the distinct philosophies of these approaches.\nOur approach leads to the usual electrical conductivity tensor in the\nlong-wavelength limit; in the absence of any scattering mechanisms, the dc\ndivergence of that tensor is due to the free current density and the\nfinite-frequency generalization of the anomalous Hall contribution arises from\na combination of bound and free current densities. As well, in the limit that\nthe electronic ground state is that of a trivial insulator, our expressions\nreduce to those expected for the unperturbed polarization and magnetization,\nand the electric susceptibility."
    },
    {
        "anchor": "Co-existence of classical snake states and Aharanov-Bohm oscillations\n  along graphene p-n junctions: Snake states and Aharonov-Bohm interferences are examples of\nmagnetoconductance oscillations that can be observed in a graphene p-n\njunction. Even though they have already been reported in suspended and\nencapsulated devices including different geometries, a direct comparison\nremains challenging as they were observed in separate measurements. Due to the\nsimilar experimental signatures of these effects a consistent assignment is\ndifficult, leaving us with an incomplete picture. Here we present measurements\non p-n junctions in encapsulated graphene revealing several sets of\nmagnetoconductance oscillations allowing for their direct comparison. We\nanalysed them with respect to their charge carrier density, magnetic field,\ntemperature and bias dependence in order to assign them to either snake states\nor Aharonov-Bohm oscillations. Furthermore we were able to consistently assign\nthe various Aharonov-Bohm interferences to the corresponding area which the\nedge states enclose. Surprisingly, we find that snake states and Aharonov-Bohm\ninterferences can co-exist within a limited parameter range.",
        "positive": "On the accuracy of surface hopping dynamics in condensed phase\n  non-adiabatic problems: We perform extensive benchmark comparisons of surface hopping dynamics with\nnumerically exact calculations for the spin-boson model over a wide range of\nenergetic and coupling parameters as well as temperature. We find that\ndeviations from golden-rule scaling in the Marcus regime are generally small\nand depend sensitively on the energetic bias between electronic states. Fewest\nswitched surface hopping (FSSH) is found to be surprisingly accurate over a\nlarge swath of parameter space. The inclusion of decoherence corrections via\nthe augmented FSSH (A-FSSH) algorithm improves the accuracy of dynamical\nbehavior compared to exact simulations, but the effects are generally not\ndramatic, at least for the case of an environment modeled with the commonly\nused Debye spectral density."
    },
    {
        "anchor": "Scattering of Hot Excitons in Quantum Wells: The scattering probabilities of hot excitons in narrow quantum wells (QWs)are\nobtained. The exciton-phonon matrix element is considered by using an envelope\nfunction Hamiltonian approach in the strong quantization limit where the QW\nwidth is smaller than the exciton bulk Bohr radius. The Fr\\\"{o}hlich-like\ninteraction is taken into account and the contribution of the confined and\ninterface modes to the scattering probability are calculated as a function of\nquantum well width, electron and hole effective masses, and in-plane\ncenter-of-mass kinetic energy. Inter- and intra-subband excitonic transitions\nare discussed in term of the phonon scalar potential selectionrules. It is\nshown that even parity electrostatic potential states for confined and\ninterface modes give the main contribution to the excitonic scattering rate.\nThe consequences of exciton relaxation and scattering probability present for\nthe multiphonon resonance Raman scattering in narrow QWs are briefly discussed.",
        "positive": "Strong shape dependence of the Morin transition in alpha-Fe2O3\n  single-crystalline nanostructures: Single-crystalline alpha-Fe2O3 nanorings (short nanotubes) and nanotubes were\nsynthesized by a hydrothermal method. High-resolution transmission electron\nmicroscope and selected-area electron diffraction confirm that the axial\ndirections of both nanorings and nanotubes are parallel to the crystalline\nc-axis. What is intriguing is that the Morin transition occurs at about 210 K\nin the short nanotubes with a mean tube length of about 115 nm and a mean outer\ndiameter of 169 nm while it disappears in the nanotubes with a mean tube length\nof about 317 nm and a mean outer diameter of 148 nm. Detailed analyses of\nmagnetization data, x-ray diffraction spectra, and room-temperature Mossbauer\nspectra demonstrate that this very strong shape dependence of the Morin\ntransition is intrinsic to hematite. We can quantitatively explain this\nintriguing shape dependence in terms of opposite signs of the surface magnetic\nanisotropy constants in the surface planes parallel and perpendicular to the\nc-axis (that is, K_parallel = -0.37 erg/cm^2 and K_perp = 0.42 erg/cm^{2})."
    },
    {
        "anchor": "Quantum Hall effect in narrow graphene ribbons: The edge states in the integer quantum Hall effect are known to be\nsignificantly affected by electrostatic interactions leading to the formation\nof compressible and incompressible strips at the boundaries of Hall bars. We\nshow here, in a combined experimental and theoretical analysis, that this does\nnot hold for the quantum Hall effect in narrow graphene ribbons. In our\ngraphene Hall bar, which is only 60 nm wide, we observe the quantum Hall effect\nup to Landau level index k=2 and show within a zero free-parameter model that\nthe spatial extent of the compressible and incompressible strips is of a\nsimilar magnitude as the magnetic length. We conclude that in narrow graphene\nribbons the single-particle picture is a more appropriate description of the\nquantum Hall effect and that electrostatic effects are of minor importance.",
        "positive": "3e tunneling processes in a superconducting single-electron tunneling\n  transistor: A current due to a tunneling event that involves three times the charge of an\nelectron was observed in the current - voltage characteristics of a\nsuperconducting single-electron tunneling transistor. In this tunnel event, a\nCooper pair tunnels through one tunnel barrier simultaneously with a\nquasiparticle that tunnels through a second tunnel barrier which is about 0.5\nmicrons distant from the first tunnel barrier. This current was observed in a\nbias regime where current flow due to sequential quasiparticle tunneling is\nforbidden due to the Coulomb blockade."
    },
    {
        "anchor": "Optically-patterned nuclear doughnuts in GaAs/MnAs heterostructures: We demonstrate a scheme for optically patterning nuclear spin polarization in\nsemiconductor/ferromagnet heterostructures. A scanning time-resolved Kerr\nrotation microscope is used to image the nuclear spin polarization that results\nwhen GaAs/MnAs epilayers are illuminated with a focused laser having a Gaussian\nprofile. Rather than tracking the intensity profile of the laser spot, these\nimages reveal that the nuclear polarization forms an annular lateral structure\nhaving circular symmetry with a dip rather than a peak at its center.",
        "positive": "Energetics and dynamics of H$_2$ adsorbed in a nanoporous material at\n  low temperature: Molecular hydrogen adsorption in a nanoporous metal organic framework\nstructure (MOF-74) was studied via van der Waals density-functional\ncalculations. The primary and secondary binding sites for H$_2$ were confirmed.\nThe low-lying rotational and translational energy levels were calculated, based\non the orientation and position dependent potential energy surface at the two\nbinding sites. A consistent picture is obtained between the calculated\nrotational-translational transitions for different H$_2$ loadings and those\nmeasured by inelastic neutron scattering exciting the singlet to triplet (para\nto ortho) transition in H$_2$. The H$_2$ binding energy after zero point energy\ncorrection due to the rotational and translational motions is predicted to be\n$\\sim$100 meV in good agreement with the experimental value of $\\sim$90 meV."
    },
    {
        "anchor": "Enhanced Magnetism & Time - Stable Remanence at the Interface of\n  Hematite and Carbon Nanotubes: The interface of two dissimilar materials is well known for surprises in\ncondensed matter, and provides avenues for rich physics as well as seeds for\nfuture technological advancements. We present some exciting magnetization (M)\nand remnant magnetization ($\\mu$) results, which conclusively arise at the\ninterface of two highly functional materials, namely the graphitic shells of a\ncarbon nanotube (CNT) and $\\alpha$-Fe$_2$O$_3$, a Dzyaloshinskii-Moriya\nInteraction (DMI) driven weak ferromagnet (WFM) and piezomagnet (PzM). We show\nthat the encapsulation inside CNT leads to a very significant enhancement in M\nand correspondingly in $\\mu$, a time- stable part of the remanence, exclusive\nto the WFM phase. Up to 70% of in-field magnetization is retained in the form\nof $\\mu$ at the room temperature. Lattice parameter of CNT around the Morin\ntransition of the encapsulate exhibits a clear anomaly, confirming the novel\ninterface effects. Control experiments on bare $\\alpha$-Fe$_2$O$_3$ nanowires\nbring into fore that the weak ferromagnets such as $\\alpha$-Fe$_2$O$_3$ as are\nnot as weak, as far as their remanence and its stability with time is\nconcerned, and encapsulation inside CNT leads to a substantial enhancement in\nthese functionalities.",
        "positive": "Quantum interference and electron correlation in charge transport\n  through triangular quantum dot molecules: We study the charge transport properties of triangular quantum dot molecule\n(TQDM) connected to metallic electrodes, taking into account all correlation\nfunctions and relevant charging states. The quantum interference (QI) effect of\nTQDM resulting from electron coherent tunneling between quantum dots is\nrevealed and well interpreted by the long distance coherent tunneling\nmechanism. The spectra of electrical conductance of TQDM with charge filling\nfrom one to six electrons clearly depict the many-body and topological effects.\nThe calculated charge stability diagram for conductance and total occupation\nnumbers match well with the recent experimental measurements. We also\ndemonstrate that the destructive QI effect on the tunneling current of TQDM is\nrobust with respect to temperature variation, making the single electron QI\ntransistor feasible at higher temperatures."
    },
    {
        "anchor": "Transport through side-coupled multilevel double quantum dots in the\n  Kondo regime: We analyze the transport properties of a double quantum dot device in the\nside-coupled configuration. A small quantum dot (QD), having a single relevant\nelectronic level, is coupled to source and drain electrodes. A larger QD, whose\nmultilevel nature is considered, is tunnel-coupled to the small QD. A Fermi\nliquid analysis shows that the low temperature conductance of the device is\ndetermined by the total electronic occupation of the double QD. When the small\ndot is in the Kondo regime, an even number of electrons in the large dot leads\nto a conductance that reaches the unitary limit, while for an odd number of\nelectrons a two stage Kondo effect is observed and the conductance is strongly\nsuppressed. The Kondo temperature of the second stage Kondo effect is strongly\naffected by the multilevel structure of the large QD. For increasing level\nspacing, a crossover from a large Kondo temperature regime to a small Kondo\ntemperature regime is obtained when the level spacing becomes of the order of\nthe large Kondo temperature.",
        "positive": "Spin Diode Behavior in Transport Through Single-Molecule Magnets: We study transport properties of a single-molecule magnet (SMM) weakly\ncoupled to one nonmagnetic and one ferromagnetic lead. Using the diagrammatic\ntechnique in real time, we calculate transport in the sequential and\ncotunneling regimes for both ferromagnetic and antiferromagnetic exchange\ncoupling between the molecule's LUMO level and the core spin. We show that the\ncurrent flowing through the system is asymmetric with respect to the bias\nreversal, being strongly suppressed for particular bias polarizations. Thus,\nthe considered system presents a prototype of a SMM spin diode. In addition, we\nalso show that the functionality of such a device can be tuned by changing the\nposition of the molecule's LUMO level and strongly depends on the type of\nexchange interaction."
    },
    {
        "anchor": "Majorana states in helical Shiba chains and ladders: Motivated by recent proposals to realize Majorana bound states in chains and\narrays of magnetic atoms deposited on top of a superconductor, we study the\ntopological properties of various chain structures, ladders and two-dimensional\narrangements exhibiting magnetic helices. We show that magnetic domain walls\nwhere the chirality of a magnetic helix is inverted support two protected\nMajorana states giving rise to a tunneling conductance peak twice the height of\na single Majorana state. The topological properties of coupled chains exhibit\nnontrivial behaviour as a function of the number of chains beyond the even-odd\ndichotomy expected from the simple $\\mathbb{Z}_2$ nature of coupled Majorana\nstates. In addition, it is possible that a ladder of two or more coupled chains\nexhibit Majorana edge states even when decoupled chains are trivial. We\nformulate a general criterion for the number of Majorana edge states in\nmultichain ladders and discuss some experimental consequences of our findings.",
        "positive": "Chaos in Magnetic Nanocontact Vortex Oscillators: We present an experimental study of spin-torque driven vortex\nself-oscillations in magnetic nanocontacts. We find that above a certain\nthreshold in applied currents, the vortex gyration around the nanocontact is\nmodulated by relaxation oscillations, which involve periodic reversals of the\nvortex core. This modulation leads to the appearance of commensurate but also\nmore interestingly here, incommensurate states, which are characterized by\ndevil's staircases in the modulation frequency. We use frequency- and\ntime-domain measurements together with advanced time-series analyses to provide\nexperimental evidence of chaos in incommensurate states of vortex oscillations,\nin agreement with theoretical predictions."
    },
    {
        "anchor": "Pauli spin blockade and the ultrasmall magnetic field effect: Based on the spin-blockade model for organic magnetoresistance we present an\nanalytic expression for the polaron-bipolaron transition rate, taking into\naccount the effective nuclear fields on the sites. We reveal the physics\nproducing qualitatively different magnetoconductance line shapes as well as the\nultrasmall magnetic field effect, and we study the role of the ratio between\nthe intersite hopping rate and the typical magnitude of the nuclear fields. Our\nfindings are in agreement with recent experiments and numerical simulations.",
        "positive": "Demonstration of NV-detected $^{13}$C NMR at 4.2 T: The nitrogen-vacancy (NV) center in diamond has enabled studies of nanoscale\nnuclear magnetic resonance (NMR) and electron paramagnetic resonance with high\nsensitivity in small sample volumes. Most NV-detected NMR (NV-NMR) experiments\nare performed at low magnetic fields. While low fields are useful in many\napplications, high-field NV-NMR with fine spectral resolution, high signal\nsensitivity, and the capability to observe a wider range of nuclei is\nadvantageous for surface detection, microfluidic, and condensed matter studies\naimed at probing micro- and nanoscale features. However, only a handful of\nexperiments above 1 T were reported. Herein, we report $^{13}$C NV-NMR\nspectroscopy at 4.2 T, where the NV Larmor frequency is 115 GHz. Using an\nelectron-nuclear double resonance technique, we successfully detect NV-NMR of\ntwo diamond samples. The analysis of the NMR linewidth based on the dipolar\nbroadening theory of Van Vleck shows that the observed linewidths from sample 1\nare consistent with the intrinsic NMR linewidth of the sample. For sample 2 we\nfind a narrower linewidth of 44 ppm. This work paves the way for new\napplications of nanoscale NV-NMR."
    },
    {
        "anchor": "Voltage control of skyrmions: creation, annihilation and zero-magnetic\n  field stablization: Voltage manipulation of skyrmions is a promising path towards low-energy\nspintronic devices. Here, voltage effects on skyrmions in a GdOx/Gd/Co/Pt\nheterostructure are observed experimentally. The results show that the skyrmion\ndensity can be both enhanced and depleted by the application of an electric\nfield, along with the ability, at certain magnetic fields to completely switch\nthe skyrmion state on and off. Further, a zero magnetic field skyrmion state\ncan be stablized under a negative bias voltage using a defined voltage and\nmagnetic field sequence. The voltage effects measured here occur on a\nfew-second timescale, suggesting an origin in voltage-controlled magnetic\nanisotropy rather than ionic effects. By investigating the skyrmion nucleation\nrate as a function of temperature, we extract the energy barrier to skyrmion\nnucleation in our sample. Further, micromagnetic simulations are used to\nexplore the effect of changing the anisotropy and Dzyaloshinskii-Moriya\ninteraction on skyrmion density. Our work demonstrates the control of skyrmions\nby voltages, showing functionalities desirable for commercial devices.",
        "positive": "Optical refrigeration with coupled quantum wells: Refrigeration of a solid-state system with light has potential applications\nfor cooling small-scale electronics and photonics. We show theoretically that\ntwo coupled semiconductor quantum wells are efficient cooling media for optical\nrefrigeration because they support long-lived indirect electron-hole pairs.\nThermal excitation of these pairs to distinct higher-energy states with faster\nradiative recombination allows an efficient escape channel to remove thermal\nenergy from the system. This allows reaching much higher cooling efficiencies\nthan with single quantum wells. From band-diagram calculations along with an\nexperimentally realistic level scheme we calculate the cooling efficiency and\ncooling yield of different devices with coupled quantum wells embedded in a\nsuspended nanomembrane. The dimension and composition of the quantum wells\nallow optimizing either of these quantities, which cannot, however, be\nmaximized simultaneously. Quantum-well structures with electrical control allow\ntunability of carrier lifetimes and energy levels so that the cooling\nefficiency can be optimized over time as the thermal population decreases due\nto the cooling."
    },
    {
        "anchor": "Discovery of highly spin-polarized conducting surface states in the\n  strong spin-orbit coupling semiconductor Sb$_2$Se$_3$: Majority of the A$_2$B$_3$ type chalcogenide systems with strong spin-orbit\ncoupling, like Bi$_2$Se$_3$, Bi$_2$Te$_3$ and Sb$_2$Te$_3$ etc., are\ntopological insulators. One important exception is Sb$_2$Se$_3$, where a\ntopological non-trivial phase was argued to be possible under ambient\nconditions, but such a phase could be detected to exist only under pressure. In\nthis Letter, we show that like Bi$_2$Se$_3$, Sb$_2$Se$_3$, displays generation\nof highly spin-polarized current under mesoscopic superconducting point\ncontacts as measured by point contact Andreev reflection spectroscopy. In\naddition, we observe a large negative and anisotropic magnetoresistance in\nSb$_2$Se$_3$, when the field is rotated in the basal plane. However, unlike in\nBi$_2$Se$_3$, in case of Sb$_2$Se$_3$ a prominent quasiparticle interference\n(QPI) pattern around the defects could be obtained in STM conductance imaging.\nThus, our experiments indicate that Sb$_2$Se$_3$ is a regular band insulator\nunder ambient conditions, but due to it's high spin-orbit coupling, non-trivial\nspin-texture exists on the surface and the system could be on the verge of a\ntopological insulator phase.",
        "positive": "Boron nanotube structure explored by evolutionary computations: In this work, we explore the structure of single-wall boron nanotubes with\nlarge diameters (about 21~{\\AA}) and a broad range of surface densities of\natoms. The computations are done using an evolutionary approach combined with a\nnearest neighbors model Hamiltonian. For the most stable nanotubes, the number\nof 5-coordinated boron atoms is about $63\\%$ of the total number of atoms\nforming the nanotubes, whereas about $11\\%$ are boron vacancies. For hole\ndensities smaller than about 0.22, the boron nanotubes exhibit randomly\ndistributed hexagonal holes and are more stable than a flat stripe structure\nand a quasi-flat B$_{36}$ cluster. For larger hole densities ($> 0.22$) the\nboron nanotubes resemble porous tubular structures with hole sizes that depend\non the surface densities of boron atoms."
    },
    {
        "anchor": "The number of transmission channels through a single-molecule junction: We calculate transmission eigenvalue distributions for Pt-benzene-Pt and\nPt-butadiene-Pt junctions using realistic state-of-the-art many-body\ntechniques. An effective field theory of interacting $\\pi$-electrons is used to\ninclude screening and van der Waals interactions with the metal electrodes. We\nfind that the number of dominant transmission channels in a molecular junction\nis equal to the degeneracy of the molecular orbital closest to the metal Fermi\nlevel.",
        "positive": "Topological phase transitions, invariants and enriched bulk-edge\n  correspondences in fermionic gapless systems with extended Fermi surface: Topological phases and topological phase transitions (TPT) are among the most\nfantastic phenomena in Nature. Here we show that injecting a current may lead\nto new topological phases, especially new gapless topological metallic phases\nwith extended Fermi surfaces (FSs) through novel class of TPTs in the bulk or\nthe boundary. Specifically, we study the quantum anomalous Hall (QAH) system in\na square lattice under various forms of injecting currents. In addition to the\npreviously known Chern insulator (which will be called even Chern insulator\nhere), band insulator and band metal (BM), we find three new topological phases\nwe name as: the gapped odd Chern insulator (Odd CI), the gapless odd Chern\nmetal (Odd CM) and even Chern metal (Even CM). The Chern number may not be\neffective anymore in characterizing the topological gapless phases with\nextended FS. It is the Hall conductance which acts as the new topological\ninvariant in such gapless systems. Its jump is a universal integer or\nnon-integer across the even CM/BM or odd CM/BM TPT respectively where there is\nalso a corresponding TPT in the Longitudinal (L-)edge modes. The Odd/even CM to\nBM transition is a novel class of TPT without any non-analyticity in the ground\nstate energy density. This presents the first example of a TPT which is not a\nquantum phase transition (QPT). The original bulk-edge correspondence is\nenriched into bulk/Longitudinal (L-)/Transverse (T-) edge correspondence. The\nL-edge reconstruction may happen earlier, later or at the same time as the bulk\nTPT respectively in the even CI/odd CI/odd CM sequence with the edge dynamic\nexponent $ z_L=3 $, in the even CI/even CM/odd CM sequence with $ z_L=2 $ or a\ndirect even CI/odd CM with a flat edge. The disappearance of the T-edge always\nhappen at the same time as the bulk TPT with a universal edge critical\nbehaviour."
    },
    {
        "anchor": "Surface Percolation and Growth. An alternative scheme for breaking the\n  diffraction limit in optical patterning: A nanopatterning scheme is presented by which the structure height can be\ncontrolled in the tens of nanometers range and the lateral resolution is a\nfactor at least three times better than the point spread function of the\nwriting beam. The method relies on the initiation of the polymerization\nmediated by a very inefficient energy transfer from a fluorescent dye molecule\nafter single photon absorption. The mechanism has the following distinctive\nsteps: the dye adsorbs on the substrate surface with a higher concentration\nthan in the bulk, upon illumination it triggers the polymerization, then\nisolated islands develop and merge into a uniform structure (percolation),\nwhich subsequently grows until the illumination is interrupted. This\npercolation mechanism has a threshold that introduces the needed nonlinearity\nfor the fabrication of structures beyond the diffraction limit.",
        "positive": "Explicit Gauge Fixing for Degenerate Multiplets: A Generic Setup for\n  Topological Orders: We supply basic tools for the study of the topological order of a multiplet\nwhich is an eigenspace of a finite-dimensional normal operator with continuous\nparameters. We allow intrinsic degeneracies within the multiplet where a\nwell-known standard procedure does not work. As an important example, we give\nnovel expressions for a spin Hall conductance for unitary superconductors with\nequal spin pairing. Generic topological orders will be treated in this unified\nmanner particularly with nontrivial topological degeneracies."
    },
    {
        "anchor": "Spin blockade and coherent dynamics of high-spin states in a\n  three-electron double quantum dot: Asymmetry in a three-electron double quantum dot (DQD) allows spin blockade,\nwhen spin-3/2 (quadruplet) states and spin-1/2 (doublet) states have different\ncharge configurations. We have observed this DQD spin blockade near the\n(1,2)-(2,1) charge transition using a pulsed-gate technique and a charge\nsensor. We then use this spin blockade to detect Landau-Zener-St\\\"uckelberg\n(LZS) interference and coherent oscillations between the spin quadruplet and\ndoublet states. Such studies add to our understandings of coherence and control\nproperties of three-spin states in a double dot, which in turn would benefit\nthe explorations into various qubit encoding schemes in semiconductor\nnanostructures.",
        "positive": "Resonant interaction in chiral, Eshelby-twisted van der Waals atomic\n  layers: We study the electronic structures of chiral, Eshelby-twisted van der Waals\natomic layers with a particular focus on a chiral twisted graphite (CTG), a\ngraphene stack with a constant twist angle $\\theta$ between successive layers.\nWe show that each CTG can host infinitely many resonant states which arise from\nthe interaction between the degenerate monolayer states of the constituent\nlayers. Each resonant state has a screw rotational symmetry, and may have a\nsmaller reduced Brillouin zone than other non-resonant states in the same\nstructure. And each CTG can have the resonant states with up to four different\nscrew symmetries. We derive the energies and wave functions of the resonant\nstates in a universal form of a one-dimensional chain regardless of $\\theta$,\nand show that these states exhibit a clear optical selection rule for\ncircularly polarized light. Finally, we discuss the uniqueness and existence of\nthe exact center of the lattice and the self-similarity of the wave amplitudes\nof the resonant states."
    },
    {
        "anchor": "Effect of incoherent scattering on shot noise correlations in the\n  quantum Hall regime: We investigate the effect of incoherent scattering in a Hanbury Brown and\nTwiss situation with electrons in edge states of a three-terminal conductor\nsubmitted to a strong perpendicular magnetic field. The modelization of\nincoherent scattering is performed by introducing an additional voltage probe\nthrough which the current is kept equal to zero which causes voltage\nfluctuations at this probe. It is shown that inelastic scattering can lead in\nthis framework to positive correlations, whereas correlations remain always\nnegative for quasi-elastic scattering.",
        "positive": "Theory of nonlinear excitonic response of hybrid organic perovskites in\n  the regime of strong light-matter coupling: We present a quantitative study of the nonlinear optical response of layered\nperovskites placed inside planar photonic microcavities in the regime of strong\nlight matter coupling, when excitonic and photonic modes hybridize and give\nrise to cavity polaritons. Two sources of nonlinearity are specified, the\nsaturation of the excitonic transition with increase of the optical pump and\nCoulomb interaction between the excitons. It is demonstrated, that peculiar\nform of the interaction potential, specific to multilayer structure of organic\nperovskites, is responsible for substantial increase of the exciton binding\nenergy and Rabi splitting with respect to conventional semiconductor systems.\nThis results in dominant contribution of the Rabi splitting quench effect in\nthe nonlinear optical response. Moreover, due to the tightly bound character of\nexcitons, the density of Mott transition is essentially higher, allowing to\nreach extremely large polariton blueshifts of about 50 meV, which is order of\nmagnitude higher than in conventional semiconductors."
    },
    {
        "anchor": "Long-lived electron spins in a modulation doped (100) GaAs quantum well: We have measured T1 spin lifetimes of a 14 nm modulation-doped (100) GaAs\nquantum well using a time-resolved pump-probe Kerr rotation technique. The\nquantum well was selected by tuning the wavelength of the probe laser. T1\nlifetimes in excess of 1 microsecond were measured at 1.5 K and 5.5 T,\nexceeding the typical T2* lifetimes that have been measured in GaAs and II-VI\nquantum wells by orders of magnitude. We observed effects from nuclear\npolarization, which were largely removable by simultaneous nuclear magnetic\nresonance, along with two distinct lifetimes under some conditions that likely\nresult from probing two differently-localized subsets of electrons.",
        "positive": "Spin-wave localization on phasonic defects in one-dimensional magnonic\n  quasicrystal: We report on the evolution of the spin-wave spectrum under structural\ndisorder introduced intentionally into one-dimensional magnonic quasicrystal.\nWe study theoretically a system composed of ferromagnetic strips arranged in a\nFibonacci sequence. We considered several stages of disorder in the form of\nphasonic defects, where different rearrangements of strips are introduced. By\ntransition from the quasiperiodic order towards disorder, we show a gradual\ndegradation of spin-waves fractal spectra and closing of the frequency gaps. In\nparticular, the phasonic defects lead to the disappearance of the van Hove\nsingularities at the frequency gap edges by moving modes into the frequency\ngaps and appearing new modes inside the frequency gaps. These modes disperse\nand eventually can close the gap, with increasing disorder levels. The work\nreveals how the the presence of disorder modifies the intrinsic spin wave\nlocalization existing in undefected magnonic quasicrystals. The paper\ncontributes to the knowledge of magnonic Fibonacci quasicrystals and opens the\nway to study of the phasonic defects in two-dimensional magnonic quasicrystals."
    },
    {
        "anchor": "Resonant Tunneling through S- and U-shaped Graphene Nanoribbons: We theoretically investigate resonant tunneling through S- and U-shaped\nnanostructured graphene nanoribbons. A rich structure of resonant tunneling\npeaks are found eminating from different quasi-bound states in the middle\nregion. The tunneling current can be turned on and off by varying the Fermi\nenergy. Tunability of resonant tunneling is realized by changing the width of\nthe left and/or right leads and without the use of any external gates.",
        "positive": "Nonequilibrium spin texture within a thin layer below the surface of\n  current-carrying topological insulator Bi$_2$Se$_3$: A first-principles\n  quantum transport study: We predict that unpolarized charge current injected into a ballistic thin\nfilm of prototypical topological insulator (TI) Bi$_2$Se$_3$ will generate a\n{\\it noncollinear spin texture} $\\mathbf{S}(\\mathbf{r})$ on its surface.\nFurthermore, the nonequilibrium spin texture will extend into $\\simeq 2$ nm\nthick layer below the TI surfaces due to penetration of evanescent\nwavefunctions from the metallic surfaces into the bulk of TI. Averaging\n$\\mathbf{S}(\\mathbf{r})$ over few \\AA{} along the longitudinal direction\ndefined by the current flow reveals large component pointing in the transverse\ndirection. In addition, we find an order of magnitude smaller out-of-plane\ncomponent when the direction of injected current with respect to Bi and Se\natoms probes the largest hexagonal warping of the Dirac-cone dispersion on TI\nsurface. Our analysis is based on an extension of the nonequilibrium Green\nfunctions combined with density functional theory (NEGF+DFT) to situations\ninvolving noncollinear spins and spin-orbit coupling. We also demonstrate how\nDFT calculations with properly optimized local orbital basis set can precisely\nmatch putatively more accurate calculations with plane-wave basis set for the\nsupercell of Bi$_2$Se$_3$."
    },
    {
        "anchor": "Band Structure Engineering of Interfacial Semiconductors Based on\n  Atomically Thin Lead Iodide Crystals: To explore new constituents in two-dimensional materials and to combine their\nbest in van der Waals heterostructures, are in great demand as being unique\nplatform to discover new physical phenomena and to design novel functionalities\nin interface-based devices. Herein, PbI2 crystals as thin as few-layers are\nfirst synthesized, particularly through a facile low-temperature solution\napproach with the crystals of large size, regular shape, different thicknesses\nand high-yields. As a prototypical demonstration of flexible band engineering\nof PbI2-based interfacial semiconductors, these PbI2 crystals are subsequently\nassembled with several transition metal dichalcogenide monolayers. The\nphotoluminescence of MoS2 is strongly enhanced in MoS2/PbI2 stacks, while a\ndramatic photoluminescence quenching of WS2 and WSe2 is revealed in WS2/PbI2\nand WSe2/PbI2 stacks. This is attributed to the effective heterojunction\nformation between PbI2 and these monolayers, but type I band alignment in\nMoS2/PbI2 stacks where fast-transferred charge carriers accumulate in MoS2 with\nhigh emission efficiency, and type II in WS2/PbI2 and WSe2/PbI2 stacks with\nseparated electrons and holes suitable for light harvesting. Our results\ndemonstrate that MoS2, WS2, WSe2 monolayers with very similar electronic\nstructures themselves, show completely distinct light-matter interactions when\ninterfacing with PbI2, providing unprecedent capabilities to engineer the\ndevice performance of two-dimensional heterostructures.",
        "positive": "Mesoscopic coherence effect in superconductor-metallic ferromagnet\n  structures: The boundary condition in Eq.6 is invalid."
    },
    {
        "anchor": "Half-Integer Filling Factor States in Quantum Dots: Emergence of half-integer filling factor states, such as nu=5/2 and 7/2, is\nfound in quantum dots by using numerical many-electron methods. These states\nhave interesting similarities and differences with their counterstates found in\nthe two-dimensional electron gas. The nu=1/2 states in quantum dots are shown\nto have high overlaps with the composite fermion states. The lower overlap of\nthe Pfaffian state indicates that electrons might not be paired in quantum dot\ngeometry. The predicted nu=5/2 state has high spin polarization which may have\nimpact on the spin transport through quantum dot devices.",
        "positive": "Spin Hall effect due to intersubband-induced spin-orbit interaction in\n  symmetric quantum wells: We investigate the intrinsic spin Hall effect in two-dimensional electron\ngases in quantum wells with two subbands, where a new intersubband-induced\nspin-orbit coupling is operative. The bulk spin Hall conductivity\n$\\sigma^z_{xy}$ is calculated in the ballistic limit within the standard Kubo\nformalism in the presence of a magnetic field $B$ and is found to remain finite\nin the B=0 limit, as long as only the lowest subband is occupied. Our\ncalculated $\\sigma^z_{xy}$ exhibits a nonmonotonic behavior and can change its\nsign as the Fermi energy (the carrier areal density $n_{2D}$) is varied between\nthe subband edges. We determine the magnitude of $\\sigma^z_{xy}$ for realistic\nInSb quantum wells by performing a self-consistent calculation of the\nintersubband-induced spin-orbit coupling."
    },
    {
        "anchor": "To gap or not to gap? Mass distortions and edge modes in graphene\n  armchair nanoribbons: We investigate, in the framework of macroscopic Dirac model, the spectrum,\ncharge density and conductivity of metallic armchair graphene nanoribbons in\npresence of different mass terms. We reveal the conditions and symmetries\ngoverning the presence of edge modes in the system. Depending on the mass terms\npresent they are exponentially localized gapless or gapped modes. The latter\nsituation is realized, in particular, for a full Kekule distortion. For this\ncase, we calculate the mean charge and conductivity of the ribbon, and derive\nthe traces of the presence of edge modes suitable for experimental\nverification.",
        "positive": "Spin effects induced by thermal perturbation in a normal metal/magnetic\n  insulator system: Using one of the methods of quantum nonequilibrium statistical physics we\nhave investigated the spin transport transverse to the normal\nmetal/ferromagnetic insulator interface in hybrid nanostructures. An\napproximation of the effective parameters, when each of the interacting\nsubsystems (electron spin, magnon, and phonon) is characterized by its own\neffective temperature have been considered. The generalized Bloch equations\nwhich describe the spin-wave current propagation in the dielectric have been\nderived. Finally, two sides of the spin transport \"coin\" have been revealed:\nthe diffusive nature of the magnon motion and magnon relaxation processes,\nresponsible for the spin pumping and the spin-torque effect."
    },
    {
        "anchor": "Ballistic persistent currents in disordered metallic rings: Origin of\n  puzzling experimental values: Typical persistent current ($I_{typ}$) in a normal metal ring with disorder\ndue to random grain boundaries and rough edges is calculated microscopically.\nIf disorder is due to the rough edges, a ballistic current $I_{typ}\\simeq e\nv_F/L$ is found in spite of the diffusive resistance ($ \\propto L/l$), where\n$v_F$ is the Fermi velocity, $l$ is the mean free path, and $L \\gg l$ is the\nring length. This ballistic current has a simple interpretation: It is due to a\nsingle coherent electron that moves in parallel with the edges and thus does\nnot feel the roughness. Our calculations explain a puzzling experimental result\n$I_{typ}\\simeq e v_F/L$, reported by Chandrasekhar et al. [Phys. Rev. Lett. 67,\n3578 (1991)] for metal rings of length $L \\simeq 100 l$. If disorder is due to\nthe grain boundaries, our results agree with diffusive result $I_{typ}\\simeq (e\nv_F/L) (l/L)$, derived by Cheung et al. [Phys. Rev. Lett. 62, 587 (1989)] and\nobserved by Bluhm et al. [Phys. Rev. Lett. 102, 136802 (2009)] and\nBleszynsky-Jayich et al. [Science 326, 272 (2009)].",
        "positive": "Dynamical Autler-Townes control of a phase qubit: Routers, switches, and repeaters are essential components of modern\ninformation-processing systems. Similar devices will be needed in future\nsuperconducting quantum computers. In this work we investigate experimentally\nthe time evolution of Autler-Townes splitting in a superconducting phase qubit\nunder the application of a control tone resonantly coupled to the second\ntransition. A three-level model that includes independently determined\nparameters for relaxation and dephasing gives excellent agreement with the\nexperiment. The results demonstrate that the qubit can be used as a ON/OFF\nswitch with 100 ns operating time-scale for the reflection/transmission of\nphotons coming from an applied probe microwave tone. The ON state is realized\nwhen the control tone is sufficiently strong to generate an Autler-Townes\ndoublet, suppressing the absorption of the probe tone photons and resulting in\na maximum of transmission."
    },
    {
        "anchor": "Spin negative differential resistance in edge doped zigzag graphene\n  nanoribbons: The nonlinear spin-dependent transport properties in zigzag graphene\nnanoribbons (ZGNRs) edge doped by an atom of group III and V elements are\nstudied systematically using density functional theory combined with\nnon-equilibrium Greens functions. The dopant type, acceptor or donor, and the\ngeometrical symmetry, odd or even, are found critical in determining the spin\npolarization of the current and the current-voltage characteristics. For ZGNRs\nsubstitutionally doped on the lower-side edge, the down (up) spin current\ndominates in odd-(even-)width ZGNRs under a bias voltage around 1V. Remarkably,\nin even-width ZGNRs, doped by group III elements (B and Al), negative\ndifferential resistance (NDR) occurs only for down spins. The bias range of the\nspin NDR increases with the width of ZGNRs. The clear spin NDR is not observed\nin any odd-width ZGNRs nor in even-width ZGNRs doped by group V elements (N,\nand P). This peculiar spin NDR of edge doped ZGNRs suggests potential\napplications in spintronics.",
        "positive": "Quantum information processing based on P-31 nuclear spin qubits in a\n  quasi-one-dimensional Si-28 nanowire: We suggest a new method of quantum information processing based on the\nprecise placing of P-31 isotope atoms in a quasi-one-dimensional Si-28 nanowire\nusing isotope engineering and neutron-transmutation doping of the grown\nstructures. In our structure, interqubit entanglement is based on the indirect\ninteraction of P-31 nuclear spins with electrons localized in a nanowire. This\nallows one to control the coupling between distant qubits and between qubits\nseparated by non-qubit neighboring nodes. The suggested method enables one to\nfabricate structures using present-day nanolithography. Numerical estimates\nshow the feasibility of the proposed device and method of operation."
    },
    {
        "anchor": "High-Frequency Hopping conductivity of Disordered 2D-system in the IQHE\n  Regime: High frequency (hf) conductivity in the form $\\sigma^{hf} = \\sigma_1^{hf} -\ni\\sigma_2^{hf}$ was obtained from the measurement of Surface Acoustic Waves\n(SAW) attenuation and velocity (f=30 MHz) in GaAs/AlGaAs heterostructures\n($n=1.3-7\\cdot 10^{11}cm^{-2}$). It has been shown that in the Integer Quantum\nHall Effect (IQHE) regime for all the samples at magnetic fields corresponding\nto the middle of the Hall plateaus and T=1.5 K, $\\sigma_1 / \\sigma_2 =0.14 \\pm\n0.03$. The ratio $\\sigma_1 / \\sigma_2=0.15$ points the case when the\nhigh-frequency hopping conductivity mechanism (electronic transition between\nthe localized states formed by \"tight\" pairs) is valid \\cite{1}. Dependencies\nof $\\sigma_1$ and $\\sigma_2$ on temperature and magnetic field is analyzed\nwidth of the Landau band broadened by the impurity random potential is\ndetermined.",
        "positive": "Energy spectrum and optical absorption of superlattices under strong\n  band inversion conditions: We show that in superlattices with a strong band inversion no hybridization\ngap exists. There are two points where the bands are crossing and the spectrum\nhas a shape of Dirac cones. Due to the absence of the hybridization gap the\noptical absorption does not have a threshold and goes to zero gradually with\nthe decrease of optical energy."
    },
    {
        "anchor": "Heterointerface effects on the charging energy of shallow D- ground\n  state in silicon: the role of dielectric mismatch: Donor states in Si nanodevices can be strongly modified by nearby insulating\nbarriers and metallic gates. We report here experimental results indicating a\nstrong reduction in the charging energy of isolated As dopants in Si FinFETs\nrelative to the bulk value. By studying the problem of two electrons bound to a\nshallow donor within the effective mass approach, we find that the measured\nsmall charging energy may be due to a combined effect of the insulator\nscreening and the proximity of metallic gates.",
        "positive": "Spin tunnelling in Molecular Magnets: We study spin tunneling in magnetic molecules, with special reference to Fe8.\nThe article aims to give a pedagogical discussion of what is meant by the\ntunneling of a spin, and how tunneling amplitudes or energy level splittings\nmay be calculated using path integral and discrete phase integral methods. In\nthe case of Fe8, an issue of great interest is the oscillatory tunnel\nsplittings as a function of applied magnetic field that have recently been\nobserved. These oscillations are due to the occurrence of diabolical points in\nthe magnetic field space. It is shown how this effect comes about in both the\npath-integral and the discrete phase integral methods. In the former it arises\ndue to the presence of a Berry-like phase in the action, which gives rise to an\ninterference between tunneling trajectories. In the latter, it arises due to\nthe presence of further neighbor terms in the recursion relation for the energy\neigenfunction. These terms give rise to turning points which have no analog in\nthe one-dimensional continuum quasiclassical method. Explicit results are\nobtained for the location of the diabolical points in Fe8."
    },
    {
        "anchor": "Electrically controllable cyclotron resonance: Cyclotron resonance (CR) is considered one of the fundamental phenomena in\nconducting systems. In this paper, we study CR in a gated two-dimensional (2D)\nelectron system (ES). Namely, we analyze the absorption of electromagnetic\nradiation incident normal to the gated 2DES, where a standard dielectric\nsubstrate separates the 2D electron sheet and the metallic steering electrode\n(\"gate\"); the whole system is placed in the perpendicular magnetic field. Our\nanalysis reveals the redshift of the absorption peak frequency compared to the\nelectron cyclotron frequency. The redshift appears in low-frequency regime,\nwhen the resonant frequency is much less than the frequency of Fabry-Perot\nmodes in natural resonator \"2D electron sheet - substrate - gate\". Moreover, we\nfind this shift to be dependent on the electron density of 2DES. Therefore, it\ncan be controlled by varying the gate voltage. We predict that the shift can be\nlarge in realistic gated or back-gated 2DESs. The obtained controllability of\nCR in gated 2DES opens the door for exploring new physics and applications of\nthis phenomenon.",
        "positive": "Mid-infrared Active Graphene Nanoribbon Plasmonic Waveguide Devices: Doped graphene emerges as a strong contender for active plasmonic material in\nthe mid-infrared wavelengths due to the versatile external-control of its\npermittivity-function and also its highly-compressed graphene surface plasmon\n(GSP) wavelength. In this paper, we design active plasmonic waveguide devices\nbased on electrical-modulation of doped graphene nanoribbons (GNRs) on a\nvoltage-gated inhomogeneous dielectric layer. We first develop figure-of-merit\n(FoM) formulae to characterize the performance of passive and active graphene\nnanoribbon waveguides. Based on the FoMs, we choose optimal GNRs to build a\nplasmonic shutter, which consists of a GNR placed on top of an inhomogeneous\nSiO$_2$ substrate supported by a Si nanopillar. Simulation studies show that\nfor a simple 50nm-long plasmonic shutter, the modulation contrast can exceed\n30dB. The plasmonic shutter is further extended to build a 4-port active power\nsplitter and an 8-port active network, both based on GNR cross-junction\nwaveguides. For the active power splitter, the GSP power transmission at each\nwaveguide arm can be independently controlled by an applied gate-voltage with\nhigh modulation contrast and nearly-equal power-splitting proportions. From the\nconstruct of the 8-port active network, we see that it is possible to scale up\nthe GNR cross-junction waveguides into large and complex active waveguide\nnetworks, showing great potential in an exciting new area of mid-infrared\ngraphene plasmonic integrated nanocircuits."
    },
    {
        "anchor": "Fundamental aspects of electron correlations and quantum transport in\n  one-dimensional systems: Table of contents 1. Introduction 2. Non-Fermi-liquid features of Fermi\nliquids:\n  1D physics in higher dimensions 3. Dzyaloshinskii-Larkin solution of the\nTomonaga-Luttinger model 4. Renormalization group for interacting fermions 5.\nSingle impurity in a 1D system: scattering theory for interacting electrons 6.\nBosonization solution 7. Transport in quantum wires 7.1 Conductivity and\nconductance 7.2 Dissipation in a contactless measurement 7.3 Conductance of a\nwire attached to reservoirs 7.4 Spin component of the conductance 7.5 Thermal\nconductance: Fabry-Perrot resonances of plasmons 8. Appendices",
        "positive": "Vorticity and quantum turbulence in the merging of superfluid Helium\n  nanodroplets: We have studied the merging of two $^4$He droplets at zero temperature,\ncaused by their Van der Waals mutual attraction. During the early stages of the\nmerging, density structures appear which closely match the experimental\nobservations by Vicente et al. [J. Low Temp. Phys. 121, 627 (2000)]. When the\ndroplets are merging, quantized vortex-antivortex ring pairs nucleate at the\nsurface and annihilate inside the merged droplet producing a roton burst. We\nalso observe the nucleation of quantized vortex-antivortex rings that wrap the\ndroplet surface and remain localized on the surface until they eventually decay\ninto short-wavelength surface waves. Analysis of the kinetic energy spectrum\ndiscloses the existence of a regime where turbulence caused by vortex\ninteraction and annihilation is characterized by a Kolmogorov power law. This\nis followed by another regime where roton radiation (produced by\nvortex-antivortex annihilation) dominates, whose hallmark is a weak, turbulent\nsurface dynamics. We suggest that similar processes might appear in superfluid\nhelium droplets after they capture impurities or if they are produced by\nhydrodynamic instability of a liquid jet. Experiments on collisions between\nrecently-discovered self-bound Bose-Einstein condensates should display a\nsimilar phenomenology."
    },
    {
        "anchor": "Nonadiabatic charge pumping in a one-dimensional system of\n  noninteracting electrons by an oscillating potential: Using a tight-binding model, we study one-parameter charge pumping in a\none-dimensional system of non-interacting electrons. An oscillating potential\nis applied at one site while a static potential is applied in a different\nregion. Using Floquet scattering theory, we calculate the current up to second\norder in the oscillation amplitude and exactly in the oscillation frequency.\nFor low frequency, the charge pumped per cycle is proportional to the frequency\nand therefore vanishes in the adiabatic limit. If the static potential has a\nbound state, we find that such a state has a significant effect on the pumped\ncharge if the oscillating potential can excite the bound state into the\ncontinuum states or vice versa. Finally, we use the equation of motion for the\ndensity matrix to numerically compute the pumped current for any value of the\namplitude and frequency. The numerical results confirm the unusual effect of a\nbound state.",
        "positive": "Electronic, magnetic and transport properties of Fe intercalated\n  2H-TaS$_2$ studied by means of the KKR-CPA method: The electronic, magnetic and transport properties of Fe intercalated\n2H-TaS$_2$ have been investigated by means of the Korringa-Kohn-Rostoker (KKR)\nmethod. The non-stoichiometry and disorder in the system has been accounted for\nusing the Coherent Potential Approximation (CPA) alloy theory. A pronounced\ninfluence of disorder on the spin magnetic moment has been found for the\nferro-magnetically ordered material. The same applies for the spin-orbit\ninduced orbital magnetic moment and magneto-crystalline anisotropy energy. The\ntemperature-dependence of the resistivity of disordered 2H-Fe$_{0.28}$TaS$_2$\ninvestigated on the basis of the Kubo-St\\v{r}eda formalism in combination with\nthe alloy analogy model has been found in very satisfying agreement with\nexperimental data. This also holds for the temperature dependent anomalous Hall\nresistivity $ \\rho_{\\rm xy}(T) $. The role of thermally induced lattice\nvibrations and spin fluctuations for the transport properties is discussed in\ndetail."
    },
    {
        "anchor": "Spin-valley locking for in-gap quantum dots in a MoS2 transistor: Spins confined to atomically-thin semiconductors are being actively explored\nas quantum information carriers. In transition metal dichalcogenides (TMDCs),\nthe hexagonal crystal lattice gives rise to an additional valley degree of\nfreedom with spin-valley locking and potentially enhanced spin life- and\ncoherence times. However, realizing well-separated single-particle levels, and\nachieving transparent electrical contact to address them has remained\nchallenging. Here, we report well-defined spin states in a few-layer MoS$ _2$\ntransistor, characterized with a spectral resolution of $\\sim{50~\\mu}$eV at\n${T_\\textrm{el} = 150}$~mK. Ground state magnetospectroscopy confirms a finite\nBerry-curvature induced coupling of spin and valley, reflected in a pronounced\nZeeman anisotropy, with a large out-of-plane $g$-factor of ${g_\\perp \\simeq\n8}$. A finite in-plane $g$-factor (${g_\\parallel \\simeq 0.55-0.8}$) allows us\nto quantify spin-valley locking and estimate the spin-orbit splitting\n${2\\Delta_{\\rm SO} \\sim 100~\\mu}$eV. The demonstration of spin-valley locking\nis an important milestone towards realizing spin-valley quantum bits.",
        "positive": "Interaction Effects and Pseudogap in Two-Dimensional Lateral Tunnel\n  Junctions: Tunneling characteristics of a two-dimensional lateral tunnel junction\n(2DLTJ) are reported. A pseudogap on the order of Coulomb energy is detected in\nthe tunneling density of states (TDOS) when two identical two-dimensional\nelectron systems are laterally separated by a thin energy barrier. The\nCoulombic pseudogap remains robust well into the quantum Hall regime until it\nis overshadowed by the cyclotron gap in the TDOS. The pseudogap is modified by\nin-plane magnetic field, demonstrating a non-trivial effect of in-plane\nmagnetic field on the electron-electron interaction."
    },
    {
        "anchor": "Energy relaxation at quantum Hall edge: In this work we address the recent experiment of Altimiras and collaborators,\nwhere an electron distribution function at the quantum Hall (QH) edge at\nfilling factor 2 has been measured with high precision. It has been reported\nthat the energy of electrons injected into one of the two chiral edge channels\nwith the help of a quantum point contact (QPC) is equally distributed between\nthem, in agreement with earlier predictions, one being based on the Fermi gas\napproach, and the other utilizing the Luttinger liquid theory. We argue that\nthe physics of the energy relaxation process at the QH edge may in fact be more\nrich, providing the possibility for discriminating between two physical\npictures in experiment. Namely, using the recently proposed non-equilibrium\nbosonization technique we evaluate the electron distribution function and find\nthat the initial \"double-step\" distribution created at a QPC evolves through\nseveral intermediate asymptotics, before reaching eventual equilibrium state.\nAt short distances the distribution function is found to be asymmetric due to\nnon-Gaussian current noise effects. At larger distances, where noise becomes\nGaussian, the distribution function acquires symmetric Lorentzian shape.\nImportantly, in the regime of low QPC transparencies T the width of the\nLorentzian scales linearly with T, in contrast to the case of equilibrium Fermi\ndistribution, whose width scales as square root of T. Therefore, we propose to\ndo measurements at low QPC transparencies. We suggest that the missing energy\nparadox may be explained by the nonlinear dispersion of the spectrum of edge\nstates.",
        "positive": "Strain-controlled switch between ferromagnetism and antiferromagnetism\n  in 1T-CrX2 (X = Se, Te) monolayers: We report on the strain-induced switch between ferromagnetic (FM) and\nantiferromagnetic (AFM) orderings in 1T-CrX2 (X = Se, Te) monolayers based on\nthe first-principles calculations. The CrSe2 and CrTe2 monolayers without\nstrains are found to be AFM and FM, respectively. Under the biaxial tensile\nstrain, the CrSe2 monolayer tends to be FM when the strain is larger than 2%.\nThe FM state is further stabilized when the strain is increased. Moreover, the\nCrSe2 monolayer changes to be half-metallic when the tensile strain is larger\nthan 10%. While for the CrTe2 monolayer, the critical strain at which the\ntransition between the FM and AFM states occurs is compressive, of -1%.\nRelatively small tensile strains of 4% and 2%, respectively, can enhance the\nCurie temperature of CrSe2 and CrTe2 monolayers above the room temperature. The\nstrain-induced switch between the FM and AFM states in CrSe2 (CrTe2) monolayer\ncan be understood by the competition between the AFM Cr-Cr direct exchange and\nFM Cr-Se(Te)-Cr superexchange interactions. The tunable and attractive magnetic\nand electronic properties controlled by the flexible strain are desirable for\nthe future nanoelectronic applications."
    },
    {
        "anchor": "Do the Size Effects Exist?: In this short paper we review a series of publications, some of which are our\nown, where various aspects of size effects were examined. By analyzing a series\nof examples we show that various intensive macroscopic characteristics of\nnanoobjects exhibit non-trivial size dependencies on the scale of 200 to 40 A.\nDrastic variations take place for sizes in the region 50-60 A for ordinary\nsystems, and 60-200 A in the case of magnetic systems. We argue that X-ray and\nneutron scattering gives an excellent metrological support in the domain from\n100 A to 10 A.",
        "positive": "Interfacial Ferroelectricity by van-der-Waals Sliding: Despite their ionic nature, many layered diatomic crystals avoid internal\nelectric polarization by forming a centrosymmetric lattice at their optimal\nanti-parallel van-der-Waals stacking. Here, we report a stable ferroelectric\norder emerging at the interface between two naturally-grown flakes of\nhexagonal-boron-nitride, which are stacked together in a metastable\nnon-centrosymmetric parallel orientation. We observe alternating domains of\ninverted normal polarization, caused by a lateral shift of one lattice site\nbetween the domains. Reversible polarization switching coupled to lateral\nsliding is achieved by scanning a biased tip above the surface. Our\ncalculations trace the origin of the phenomenon to a subtle interplay between\ncharge redistribution and ionic displacement, and our minimal cohesion model\npredicts further venues to explore the unique \"slidetronics\" switching."
    },
    {
        "anchor": "Polarization and localization of single-photon emitters in hexagonal\n  boron nitride wrinkles: Color centers in 2-dimensional hexagonal boron nitride (h-BN) have recently\nemerged as stable and bright single-photon emitters (SPEs) operating at room\ntemperature. In this study, we combine theory and experiment to show that\nvacancy-based SPEs selectively form at nano-scale wrinkles in h-BN with its\noptical dipole preferentially aligned to the wrinkle direction. By using\ndensity functional theory calculations, we find that the wrinkle curvature\nplays a crucial role in localizing vacancy-based SPE candidates and aligning\nthe defects symmetry plane to the wrinkle direction. By performing optical\nmeasurements on SPEs created in h-BN single-crystal flakes, we experimentally\nconfirm the wrinkle-induced generation of SPEs and their polarization alignment\nto the wrinkle direction. Our results not only provide a new route to\ncontrolling the atomic position and the optical property of the SPEs but also\nrevealed the possible crystallographic origin of the SPEs in h-BN, greatly\nenhancing their potential for use in solid-state quantum photonics and quantum\ninformation processing.",
        "positive": "Rashba coupling and spin switching through surface states of Dirac\n  semimetals: We study the effect of the Rashba spin-orbit coupling on the Fermi arcs of\ntopological Dirac semimetals. The Rashba coupling is induced by breaking the\ninversion symmetry at the surface. Remarkably, this coupling could be enhanced\nby the interaction with the substrate and controlled by an external electric\nfield. We study analytically and numerically the rotation of the spin of the\nsurface states as a function of the electron's momentum and the coupling\nstrength. Furthermore, a detailed analysis of the spin-dependent two-terminal\nconductance is presented in the clean limit and with the addition of a random\ndistribution of impurities. Depending on the magnitude of the quadratic terms\nin the Hamiltonian, the spin-flip conductance may become dominant, thus showing\nthe potential of the system for spintronic applications, since the effect is\nrobust even in the presence of disorder."
    },
    {
        "anchor": "Supercurrent Interference in Semiconductor Nanowire Josephson Junctions: Semiconductor-superconductor hybrid systems provide a promising platform for\nhosting unpaired Majorana fermions towards the realisation of fault-tolerant\ntopological quantum computing. In this study, we employ the Keldysh\nNon-Equilibrium Green's function formalism to model quantum transport in\nnormal-superconductor junctions. We analyze III-V semiconductor nanowire\nJosephson junctions (InAs/Nb) using a three-dimensional discrete lattice model\ndescribed by the Bogolubov-de Gennes Hamiltonian in the tight-binding\napproximation, and compute the Andreev bound state spectrum and current-phase\nrelations. Recent experiments [Zuo et al., Phys. Rev. Lett. 119,187704 (2017)]\nand [Gharavi et al., arXiv:1405.7455v2 (2014)] reveal critical current\noscillations in these devices, and our simulations confirm these to be an\ninterference effect of the transverse sub-bands in the nanowire. We add\ndisorder to model coherent scattering and study its effect on the critical\ncurrent oscillations, with an aim to gain a thorough understanding of the\nexperiments. The oscillations in the disordered junction are highly sensitive\nto the particular realisation of the random disorder potential, and to the gate\nvoltage. A macroscopic current measurement thus gives us information about the\nmicroscopic profile of the junction. Finally, we study dephasing in the channel\nby including elastic phase-breaking interactions. The oscillations thus\nobtained are in good qualitative agreement with the experimental data, and this\nsignifies the essential role of phase-breaking processes in III-V semiconductor\nnanowire Josephson junctions.",
        "positive": "Valley polarization in graphene-silicene-graphene heterojunction: Considering the difference of energy bands in graphene and silicene, we put\nforward a new model of the graphene-silicene-graphene (GSG) heterojunction. In\nthe GSG, we study the valley polarization properties in a zigzag nanoribbon in\nthe presence of an external electric field. We find the energy range associated\nwith the bulk gap of silicene has a valley polarization more than 95%. Under\nthe protection of the topological edge states of the silicene, the valley\npolarization remains even the small non-magnetic disorder is introduced. These\nresults have certain practical significance in applications for future valley\nvalve."
    },
    {
        "anchor": "Evidence for Majorana bound states in transport properties of hybrid\n  structures based on helical liquids: Majorana bound states can emerge as zero-energy modes at the edge of a\ntwo-dimensional topological insulator in proximity to an ordinary s-wave\nsuperconductor. The presence of an additional ferromagnetic domain close to the\nsuperconductor can lead to their localization. We consider both N-S and S-N-S\njunctions based on helical liquids and study their spectral properties for\narbitrary ferromagnetic scatterers in the normal region. Thereby, we explicitly\ncompute Andreev wave-functions at zero energy. We show under which conditions\nthese states form localized Majorana bound states in N-S and S-N-S junctions.\nInterestingly, we can identify Majorana-specific signatures in the transport\nproperties of N-S junctions and the Andreev bound levels of S-N-S junctions\nthat are robust against external perturbations. We illustrate these findings\nwith the example of a ferromagnetic double barrier (i.e. a quantum dot) close\nto the N-S boundaries.",
        "positive": "Can Barrier to Relative Sliding of Carbon Nanotube Walls Be Measured?: Interwall interaction energies, as well as barriers to relative sliding of\nthe walls along the nanotube axis, are first calculated for pairs of both\narmchair or both zigzag adjacent walls of carbon nanotubes with a wide range of\nradiuses. It is found that for the pairs with the radius of the outer wall\ngreater than 5 nm both the interwall interaction energy and barriers to the\nrelative sliding per one atom of the outer wall only slightly depends on the\nwall radius. A wide set of the measurable physical quantities determined by\nthese barriers are estimated as a function of the wall radius: shear strengths\nand diffusion coefficients for relative sliding of the walls along the axis, as\nwell as frequencies of relative axial oscillations of the walls. For\nnonreversible telescopic extension of the walls, maximum overlap of the walls\nfor which threshold static friction forces are greater than capillary forces is\nestimated. Possibility of experimental verification of the calculated barriers\nby measurements of the estimated physical quantities is discussed."
    },
    {
        "anchor": "Effects of electron scattering on the topological properties of\n  nanowires: Majorana fermions from disorder and superlattices: We focus on inducing topological state from regular, or irregular scattering\nin (i) p-wave superconducting wires and (ii) Rashba wires proximity coupled to\nan s-wave superconductor. We find that contrary to common expectations the\ntopological properties of both systems are fundamentally different: In p-wave\nwires, disorder generally has a detrimental effect on the topological order and\nthe topological state is destroyed beyond a critical disorder strength. In\ncontrast, in Rashba wires, which are relevant for recent experiments, disorder\ncan {\\it induce} topological order, reducing the need for quasiballistic\nsamples to obtain Majorana fermions. Moreover, we find that the total phase\nspace area of the topological state is conserved for long disordered Rashba\nwires, and can even be increased in an appropriately engineered superlattice\npotential.",
        "positive": "Cooling of radiative quantum-dot excitons by terahertz radiation: A\n  spin-resolved Monte Carlo carrier dynamics model: We have developed a theoretical model to analyze the anomalous cooling of\nradiative quantum dot (QD) excitons by THz radiation reported by Yusa et al\n[Proc. 24th ICPS, 1083 (1998)]. We have made three-dimensional (3D) modeling of\nthe strain and the piezoelectric field and calculated the 3D density of states\nof strain induced quantum dots. On the basis of this analysis we have developed\na spin dependent Monte Carlo model, which describes the carrier dynamics in\nQD's when the intraband relaxation is modulated by THz radiation. We show that\nTHz radiation causes resonance transfer of holes from dark to radiative states\nin strain-induced QD's. The transition includes a spatial transfer of holes\nfrom the piezoelectric potential mimima to the deformation potential minimum.\nThis phenomenon strongly enhances the QD ground state luminescence at the\nexpense of the luminescence from higher states. Our model also reproduces the\ndelayed flash of QD ground state luminescence, activated by THz radiation even\n$\\sim1$ s after the carrier generation. Our simulations suggest a more general\npossibility to cool the radiative exciton subsystem in optoelectronic devices."
    },
    {
        "anchor": "Flat bands and entanglement in the Kitaev ladder: We report the existence of \\emph{flat bands} in a p-wave superconducting\nKitaev ladder. We identify two sets of parameters for which the Kitaev ladder\nsustains flat bands. These flat bands are accompanied by highly localized\neigenstates known as compact localized states. Invoking a Bogoliubov\ntransformation, the Kitaev ladder can be mapped into an interlinked\ncross-stitch lattice. The mapping helps to reveal the compactness of the\neigenstates each of which covers only two unit cells of the interlinked\ncross-stitch lattice. The Kitaev Hamiltonian undergoes a topological-to-trivial\nphase transition when certain parameters are fine-tuned. Correlation matrix\ntechniques allow us to compute entanglement entropy of the many-body\neigenstates. The study of entanglement entropy affords fresh insight into the\ntopological phase transitions in the model. Sharp features in entanglement\nentropy when bands cross indicate a deep underlying relationship between\nentanglement entropy and dispersion.",
        "positive": "Acoustic realization of quadrupole topological insulators: A quadrupole topological insulator, being one higher-order topological\ninsulator with nontrivial quadrupole quantization, has been intensely\ninvestigated very recently. However, the tight-binding model proposed for such\nemergent topological insulators demands both positive and negative hopping\ncoefficients, which imposes an obstacle in practical realizations. Here we\nintroduce a feasible approach to design the sign of hopping in acoustics, and\nconstruct the first acoustic quadrupole topological insulator that stringently\nemulates the tight-binding model. The inherent hierarchy quadrupole topology\nhas been experimentally confirmed by detecting the acoustic responses at the\nbulk, edge and corner of the sample. Potential applications can be anticipated\nfor the topologically robust in-gap states, such as acoustic sensing and energy\ntrapping."
    },
    {
        "anchor": "Coulomb Drag for Strongly Localized Electrons: Pumping Mechanism: The mutual influence of two layers with strongly loclized electrons is\nexercised through the random Coulomb shifts of site energies in one layer\ncaused by electron hops in the other layer. We trace how these shifts give rise\nto a voltage drop in the passive layer, when a current is passed through the\nactive layer. We find that the microscopic origin of drag lies in the time\ncorrelations of the occupation numbers of the sites involved in a hop. These\ncorrelations are neglected within the conventional Miller-Abrahams scheme for\ncalculating the hopping resistance.",
        "positive": "Phonon-mediated damping of mechanical vibrations in a finite atomic\n  chain coupled to an outer environment: We study phonon-mediated damping of mechanical vibrations in a finite\nquantum-mechanical atomic-chain model. Our study is motivated by the quest to\nunderstand the quality factors (Q) of nanomechanical resonators and\nnanoelectromechanical systems (NEMS), as well as actual experiments with\nsuspended atomic chains and molecular junctions. We consider a finite atomic\nchain which is coupled to a zero-temperature outer environment, modeled as two\nadditional semi-infinite chains, thus inducing \"clamping-losses\". Weak coupling\nto the outer environment ensures that the clamping losses are small, and that\nthe initially discrete nature of the phonon spectrum is approximately\nmaintained. We then consider a phonon damping process known as \"Landau-Rumer\ndamping\", where phonons in the excited mode of vibration decay into other modes\nthrough anharmonic phonon-phonon interaction. The approximately discrete nature\nof the phonon spectrum leads to sharp nonmonotonic changes in Q as parameters\nare varied, and to the appearance of resonances in the damping. The latter\ncorrespond to the existence of decay processes where the participating phonons\napproximately conserve energy. We explore means to control the damping by\nchanging either the number of atoms in the chains or the ratio between the\nlongitudinal and transverse speeds of sound, thereby suggesting future\nexperiments to observe this resonance-like behavior."
    },
    {
        "anchor": "Proposal for detection of non-Markovian decay via current noise: We propose to detect non-Markovian decay of an exciton qubit coupled to\nmulti-mode bosonic reservoir via shot-noise measurements. Non-equilibrium\ncurrent noise is calculated for a quantum dot embedded inside a \\QTR{it}{p-i-n}\njunction. An additional term from non-Markovian effect is obtained in the\nderivation of noise spectrum. As examples, two practical photonic reservoirs,\nphoton vacuum with the inclusion of cut-off frequency and surface plasmons, are\ngiven to show that the noise may become super-Poissonian due to this\nnon-Markovian effect. Utilizing the property of super-radiance is further\nsuggested to enhance the noise value.",
        "positive": "Tunable Negative Differential Resistance in Planer Graphene Superlattice\n  Resonant Tunneling Diode: In this paper, we report on the controllable negative differential resistance\n(NDR) in a proposed planar graphene superlattice structure. High value of peak\nto valley ratio (PVR) is predicted. This is significant because of appearance\nof NDR with high PVR at low biases. Our finding is important since beside the\nother potential applications of the graphene, proposes implementation of the\ngraphene based superlattice in electronic devices such as resonant tunneling\ndiode and filters."
    },
    {
        "anchor": "Control of ultrashort optical electromagnetic pulses in carbon nanotubes\n  at low temperatures: Propagation of the alternating electromagnetic field in a system of zigzag\ncarbon nanotubes in the case of low temperatures and applied external electric\nfields are considered. The electronic system of the carbon nanotubes is\ninvestigated microscopically nonmetering an interaction with a phonon subsystem\nby the fact that the electromagnetic pulse is critically short. An efficient\nequation for the vector-potential amplitude of the alternating electromagnetic\nfield is obtained. Solutions of solitons analogs which correspond to solitons\nin the case of cosine dispersion law for the electronic subsystem have been\nelicited. The dependences of obtained nonlinear solutions on problem parameters\nand the applied external electric fields were analyzed. The possibility to\ncontrol the shape of optical pulse in wide range was shown.",
        "positive": "Delayed currents and interaction effects in mesoscopic capacitors: We propose an alternative derivation for the dynamic admittance of a gated\nquantum dot connected by a single-channel lead to an electron reservoir. Our\nderivation, which reproduces the result of Pr\\^{e}tre, Thomas, and B\\\"{u}ttiker\nfor the universal charge-relaxation resistance, shows that at low frequencies,\nthe current leaving the dot lags after the entering one by the Wigner-Smith\ndelay time. We compute the capacitance when interactions are taken into account\nonly on the dot within the Hartree-Fock approximation and study the\nCoulomb-blockade oscillations as a function of the Fermi energy in the\nreservoir. In particular we find that those oscillations disappear when the dot\nis fully `open', thus we reconcile apparently conflicting previous results."
    },
    {
        "anchor": "Spin noise spectroscopy of donor bound electrons in ZnO: We investigate the intrinsic spin dynamics of electrons bound to Al\nimpurities in bulk ZnO by optical spin noise spectroscopy. Spin noise\nspectroscopy enables us to investigate the longitudinal and transverse spin\nrelaxation time with respect to nuclear and external magnetic fields in a\nsingle spectrum. On one hand, the spin dynamic is dominated by the intrinsic\nhyperfine interaction with the nuclear spins of the naturally occurring\n$^{67}$Zn isotope. We measure a typical spin dephasing time of 23 ns in\nagreement with the expected theoretical values. On the other hand, we measure a\nthird, very high spin dephasing rate which is attributed to a high defect\ndensity of the investigated ZnO material. Measurements of the spin dynamics\nunder the influence of transverse as well as longitudinal external magnetic\nfields unambiguously reveal the intriguing connections of the electron spin\nwith its nuclear and structural environment.",
        "positive": "Wave and uncertainty properties of electrons in crystalline solids: Relations between particle and wave properties for charge carriers in\nperiodic potentials of crystalline metals and semiconductors are derived. The\nparticle aspects of electrons and holes in periodic potentials are considered\nusing properties of quasimomentum (QM), while the wave aspects are described\nemploying wave packets of Bloch waves. The two aspects are combined in the\nderivation of QM-wavelength relations for energy bands of arbitrary\nnonparabolicity and nonsphericity. An effective mass relating electron QM to\nits average velocity for spherical energy bands is defined and used to\ncalculate energy dependences of wavelengths for electrons in narrow gap\nsemiconductors, graphene and surface states of topological insulators. An\nuncertainty relation between electron quasimomentum and its spatial coordinate\nin periodic potentials is derived. It is emphasized that the described\nproperties apply to the average (not instantaneous) electron behavior.\nAnalogies between the wave and uncertainty properties of electrons in\ncrystalline solids and those in vacuum are traced."
    },
    {
        "anchor": "Superperiods and quantum statistics of Laughlin quasiparticles: Superperiodic conductance oscillations were recently observed in the\nquasiparticle interferometer, where an edge channel of the 1/3 fractional\nquantum Hall fluid encircles an island of the 2/5 fluid. We present a\nmicroscopic model of the origin of the 5h/e flux superperiod based on the\nHaldane-Halperin fractional-statistics hierarchical construction of the 2/5\ncondensate. Since variation of the applied magnetic field does not affect the\ncharge state of the island, the fundamental period comprises the minimal 2/5\nisland neutral reconstruction. The period consists of incrementing by one the\nstate number of the e/3 Laughlin quasielectron circling the island and the\nconcurrent excitation of ten e/5 quasiparticles out of the island 2/5\ncondensate. The Berry phase quantization condition yields anyonic quasiparticle\nbraiding statistics consistent with the hierarchical construction. We further\ndiscuss a composite fermion representation of quasiparticles consistent with\nthe superperiods. It is shown to be in one-to-one correspondence with the\nHaldane-Halperin theory, provided a literal interpretation of the 2/5\ncondensate as comprised of an integer multiple of two-composite fermion,\none-vortex blocks is postulated.",
        "positive": "Transport-induced suppression of nuclear field fluctuations in\n  multi-quantum-dot systems: Magnetic noise from randomly fluctuating nuclear spin ensembles is the\ndominating source of decoherence for many multi-quantum-dot multielectron spin\nqubits. Here we investigate in detail the effect of a DC electric current on\nthe coupled electron-nuclear spin dynamics in double and triple quantum dots\ntuned to the regime of Pauli spin blockade. We consider both systems with and\nwithout significant spin-orbit coupling and find that in all cases the flow of\nelectrons can induce a process of dynamical nuclear spin polarization that\neffectively suppresses the nuclear polarization gradients over neighboring\ndots. Since exactly these gradients are the components of the nuclear fields\nthat act harmfully in the qubit subspace, we believe that this presents a\nstraightforward way to extend coherence times in multielectron spin qubits by\nat least one order of magnitude."
    },
    {
        "anchor": "Magnetic and magnetotransport properties of Bi$_2$Se$_3$ thin films\n  doped by Eu: Structural, magnetic and magnetotransport properties of\n(Bi$_{1-x}$Eu$_x$)$_2$Se$_3$ thin films have been studied experimentally as a\nfunction of Eu content. The films were synthesized by MBE. It is demonstrated\nthat Eu distribution is not uniform, it enter quint-layers forming inside them\nplain (pancake-like) areas containing Eu atoms, which sizes and concentration\nincrease with the growth of Eu content. Positive magnetoresistance related to\nthe weak antilocalization was observed up to 15K. The antilocalization was not\nfollowed by weak localization as theory predicts for nontrivial topological\nstates. Surprisingly, the features of antilocalization were seen even at Eu\ncontent $x$ $=$ 0.21. With the increase of Eu content the transition to\nferromagnetic state occurs at $x$ about 0.1 and with the Curie temperature\n$\\approx$ 8K, that rises up to 64K for $x$ $=$ 0.21. At temperatures above 1-2\nK, the dephasing length is proportional to $T^{-1/2}$ indicating the dominant\ncontribution of inelastic $e-e$ scattering into electron phase breaking.\nHowever, at low temperatures the dephasing length saturates, that could be due\nto the scattering on magnetic ions.",
        "positive": "Saturated Hydrocarbons on Silicon: Quantifying Desorption with Scanning\n  Tunneling Microscopy and Quantum Theory: Electron stimulated desorption of cyclopentene from the Si(100)-2x1 surface\nis studied experimentally with cryogenic UHV STM and theoretically with\ntransport, electronic structure, and dynamical calculations. Unexpectedly for a\nsaturated hydrocarbon on silicon, desorption is observed at bias magnitudes as\nlow as 2.5 V, albeit the desorption yields are a factor of 500 to 1000 lower\nthan previously reported for unsaturated molecules on silicon. The low\nthreshold voltage for desorption can be attributed to hybridization of the\nmolecule with the silicon surface, which results in low-lying ionic resonances\nwithin 2-3 eV of the Fermi level. These resonances are long-lived, spatially\nlocalized and displaced in equilibrium with respect to the neutral state,\nresulting, upon excitation, in symmetric (positive ion) or asymmetric (negative\nion) motion of the silicon dimer atoms. This study highlights the importance of\nnuclear dynamics in silicon-based molecular electronics and suggests new\nguidelines for the control of such dynamics."
    },
    {
        "anchor": "Topological excitations in 2D spin system with high spin $s>= 1$: We construct a class of topological excitations of a mean field in a\ntwo-dimensional spin system represented by a quantum Heisenberg model with high\npowers of exchange interaction. The quantum model is associated with a\nclassical one (the continuous classical analogue) that is based on a\nLandau-Lifshitz like equation, and describes large-scale fluctuations of the\nmean field. On the other hand, the classical model is a Hamiltonian system on a\ncoadjoint orbit of the unitary group SU($2s {+} 1$) in the case of spin $s$. We\nhave found a class of mean field configurations that can be interpreted as\ntopological excitations, because they have fixed topological charges. Such\nexcitations change their shapes and grow preserving an energy.",
        "positive": "Photon-assisted electron transmission resonance through a quantum well\n  with spin-orbit coupling: Using the effective-mass approximation and Floquet theory, we study the\nelectron transmission over a quantum well in semiconductor heterostructures\nwith Dresselhaus spin-orbit coupling and an applied oscillation field. It is\ndemonstrated by the numerical evaluations that Dresselhaus spin-orbit coupling\neliminates the spin degeneracy and leads to the splitting of asymmetric\nFano-type resonance peaks in the conductivity. In turn, the splitting of\nFano-type resonance induces the spin- polarization-dependent electron-current.\nThe location and line shape of Fano-type resonance can be controlled by\nadjusting the oscillation frequency and the amplitude of external field as\nwell. These interesting features may be a very useful basis for devising\ntunable spin filters."
    },
    {
        "anchor": "Sign-switching of superexchange mediated by few electrons under\n  non-uniform magnetic field: Long range interaction between distant spins is an important building block\nfor the realization of large quantum-dot network in which couplings between\npairs of spins can be selectively addressed. Recent experiments on coherent\nlogical states oscillation between remote spins facilitated by intermediate\nelectron states has paved the first step for large scale quantum information\nprocessing. Reaching this ultimate goal requires extensive studies on the\nsuperexchange interaction on different quantum-dot spatial arrangements and\nelectron configurations. Here, we consider a linear triple-quantum-dot with two\nanti-parallel spins in the outer dots forming the logical states while various\nnumber of electrons in the middle dot forming a mediator, which facilitates the\nsuperexchange interaction. We show that the superexchange is enhanced when the\nnumber of mediating electrons increases. In addition, we show that forming a\nfour-electron triplet in the mediator dot further enhance the superexchange\nstrength. Our work can be a guide to scale up the quantum-dot array with\ncontrollable and dense connectivity.",
        "positive": "Quantum dots on the InAs(110) cleavage surface created by atom\n  manipulation: Cryogenic scanning tunneling microscopy was employed in combination with\ndensity-functional theory calculations to explore quantum dots made of In\nadatoms on the InAs(110) surface. Each adatom adsorbs at a surface site\ncoordinated by one cation and two anions, and transfers one electron to the\nsubstrate, creating an attractive quantum well for electrons in surface states.\nWe used the scanning-probe tip to assemble the positively charged adatoms into\nprecisely defined quantum dots exhibiting a bound state roughly 0.1 eV below\nthe Fermi level at an intrinsic linewidth of only ~4 meV, as revealed by\nscanning tunneling spectroscopy. For quantum-dot dimers, we observed the\nemergence of a bonding and an antibonding state with even and odd wave-function\ncharacter, respectively, demonstrating the capability to engineer\nquasi-molecular electronic states. InAs(110) constitutes a promising platform\nin this respect because highly perfect surfaces can be readily prepared by\ncleavage and charged adatoms can be generated in-situ by the scanning-probe\ntip."
    },
    {
        "anchor": "Integrating Magnetism into Semiconductor Electronics: Vision of ferromagnet/semiconductor hybrid as a strongly coupled but flexible\nspin system is presented. We analyze the experiments and argue that contrary to\nthe common sense the nonmagnetic semiconductor plays a crucial role in\nmanipulating of ferromagnetism. The magnetism of the hybrid (magnetic\nhysteresis loop and the orientation of magnetization vector in space) is tuned\nboth optically and electrically with the help of semiconductor. As a result the\nhybrid represents an elementary magnetic storage with electronic record and\nreadout",
        "positive": "Dynamic nuclear polarization and Knight shift measurements in a\n  breakdown regime of integer quantum Hall effect: Nuclear spins are polarized electrically in a breakdown regime of an\nodd-integer quantum Hall effect (QHE). Electron excitation to the upper Landau\nsubband with the opposite spin polarity flips nuclear spins through the\nhyperfine interaction. The polarized nuclear spins reduce the spin-splitting\nenergy and accelerate the QHE breakdown. The Knight shift of the nuclear spins\nis also measured by tuning electron density during the irradiation of\nradio-frequency magnetic fields."
    },
    {
        "anchor": "Voltage-controlled electron tunnelling from a single self-assembled\n  quantum dot embedded in a two-dimensional-electron-gas-based photovoltaic\n  cell: We perform high-resolution photocurrent (PC) spectroscopy to investigate\nresonantly the neutral exciton ground-state (X0) in a single InAs/GaAs\nself-assembled quantum dot (QD) embedded in the intrinsic region of an\nn-i-Schottky photodiode based on a two-dimensional electron gas (2DEG), which\nwas formed from a Si delta-doped GaAs layer. Using such a device, a single-QD\nPC spectrum of X0 is measured by sweeping the bias-dependent X0 transition\nenergy through that of a fixed narrow-bandwidth laser via the quantum-confined\nStark effect (QCSE). By repeating such a measurement for a series of laser\nenergies, a precise relationship between the X0 transition energy and bias\nvoltage is then obtained. Taking into account power broadening of the X0\nabsorption peak, this allows for high-resolution measurements of the X0\nhomogeneous linewidth and, hence, the electron tunnelling rate. The electron\ntunnelling rate is measured as a function of the vertical electric field and\ndescribed accurately by a theoretical model, yielding information about the\nelectron confinement energy and QD height. We demonstrate that our devices can\noperate as 2DEG-based QD photovoltaic cells and conclude by proposing two\noptical spintronic devices that are now feasible.",
        "positive": "Coherent Phonons in Carbon Nanotubes and Graphene: We review recent studies of coherent phonons (CPs) corresponding to the\nradial breathing mode (RBM) and G-mode in single-wall carbon nanotubes (SWCNTs)\nand graphene. Because of the bandgap-diameter relationship, RBM-CPs cause\nbandgap oscillations in SWCNTs, modulating interband transitions at terahertz\nfrequencies. Interband resonances enhance CP signals, allowing for chirality\ndetermination. Using pulse shaping, one can selectively excite\nspeci!c-chirality SWCNTs within an ensemble. G-mode CPs exhibit\ntemperature-dependent dephasing via interaction with RBM phonons. Our\nmicroscopic theory derives a driven oscillator equation with a\ndensity-dependent driving term, which correctly predicts CP trends within and\nbetween (2n+m) families. We also find that the diameter can initially increase\nor decrease. Finally, we theoretically study the radial breathing like mode in\ngraphene nanoribbons. For excitation near the absorption edge, the driving term\nis much larger for zigzag nanoribbons. We also explain how the armchair\nnanoribbon width changes in response to laser excitation."
    },
    {
        "anchor": "Quasiparticle spectroscopy as a probe of the topological phase in\n  graphene with heavy adatoms: Electrons in graphene with heavy adatoms (such as In or Tl) have been\npredicted to form a 2D topological insulator phase with a substantial spectral\ngap potentially suitable for future practical applications. In order to\nfacilitate the ongoing experimental efforts to identify this phase we perform a\ntheoretical study of its spectral properties in a model graphene system with\nrandomly distributed adatoms. Our extensive modeling shows that random heavy\nadatoms produce a full spectral gap (as opposed to a mobility gap) accompanied\nby distinctive quasiparticle interference patterns observable by means of\nFourier-transform scanning tunneling spectroscopy.",
        "positive": "Quantum transitions induced by the third cumulant of current\n  fluctuations: We investigate the transitions induced by external current fluctuations on a\nsmall probe quantum system. The rates for the transitions between the energy\nstates are calculated using the real-time Keldysh formalism for the density\nmatrix evolution. We especially detail the effects of the third cumulant of\ncurrent fluctuations inductively coupled to a quantum bit and propose a setup\nfor detecting the frequency-dependent third cumulant through the transitions it\ninduces."
    },
    {
        "anchor": "Experimental Test of the Dynamical Coulomb Blockade Theory for Short\n  Coherent Conductors: We observed the recently predicted quantum suppression of dynamical Coulomb\nblockade on short coherent conductors by measuring the conductance of a quantum\npoint contact embedded in a tunable on-chip circuit. Taking advantage of the\ncircuit modularity we measured most parameters used by the theory. This allowed\nus to perform a reliable and quantitative experimental test of the theory.\nDynamical Coulomb blockade corrections, probed up to the second conductance\nplateau of the quantum point contact, are found to be accurately normalized by\nthe same Fano factor as quantum shot noise, in excellent agreement with the\ntheoretical predictions.",
        "positive": "Strong magnon-photon coupling in ferromagnet-superconducting resonator\n  thin-film devices: We demonstrate strong magnon-photon coupling of a thin-film permalloy device\nfabricated on a coplanar superconducting resonator. A coupling strength of\n0.152 GHz and a cooperativity of 68 are found for a 30-nm-thick permalloy\nstripe. The coupling strength is tunable by rotating the biasing magnetic field\nor changing the volume of permalloy. We also observe an enhancement of\nmagnon-photon coupling in the nonlinear regime of the superconducting\nresonator, which is mediated by the nucleation of dynamic flux vortices. Our\nresults demonstrate a critical step towards future integrated hybrid systems\nfor quantum magnonics and on-chip coherent information transfer."
    },
    {
        "anchor": "Spin-orbit coupling and weak antilocalization in thermoelectric material\n  $\u03b2$-K$_{2}$Bi$_{8}$Se$_{13}$: We have studied the effect of spin-orbital coupling (SOC) on electronic\ntransport properties of the thermoelectric material\n$\\beta$-K$_{2}$Bi$_{8}$Se$_{13}$ via magnetoresistance (MR) measurements. We\nfound that the strong SOC in this material results in weak antilocalization\n(WAL) effect, which can be well described by the three-dimensional weak\nlocalization model. The phase coherence length extracted from theoretical\nfitting exhibits a power-law temperature dependence with an exponent around\n2.1, indicating that the electron phase dephasing is governed by electron -\ntransverse phonon interactions. Like in topological insulators, the WAL effect\nin $\\beta$-K$_{2}$Bi$_{8}$Se$_{13}$ can be quenched by magnetic impurities (Mn)\nbut is robust against non-magnetic impurities (Te). Although our\nmagnetotransport studies do not provide any evidences for topological surface\nstates, our analyses suggest that SOC plays an important role in determining\nthermoelectric properties of $\\beta$-K$_{2}$Bi$_{8}$Se$_{13}$.",
        "positive": "Multi-band energy spectra of spin-1/2 electrons with two-dimensional\n  magnetic modulations: The energy spectra of spin-1/2 electrons under two-dimensional magnetic field\nmodulations are calculated beyond the one-band approximation. Our formulation\nis generally applicable to a modulation field with a rectangular lattice\nsymmetry. The field distribution within a plaquette is otherwise arbitrary. The\nspectra being obtained are qualitatively different from their electric\nmodulated counterparts. Peculiar features of the spectra are that, for an\nelectron with a g factor precisely being equal to two, no matter how strong the\nmodulation is, the zero-energy level seems to be unaffected by the modulation\nand is separated from higher energy levels with a nonzero energy gap. Moreover,\nthere is a two-fold degenerancy for all states with positive energies with\nrespect to spin flip. These features agree with earlier analytical studies of\nthe periodically magnetic modulated systems."
    },
    {
        "anchor": "Non-linear spin transport in a rectifying ferromagnet/semiconductor\n  Schottky contact: The electrical creation and detection of spin accumulation in\nferromagnet/semiconductor Schottky contacts that exhibit highly non-linear and\nrectifying electrical transport is evaluated. If the spin accumulation in the\nsemiconductor is small, the expression for the spin voltage is identical to\nthat of linear transport. However, if the spin accumulation is comparable to\nthe characteristic energy scale that governs the degree of non-linearity, the\nspin detection sensitivity and the spin voltage are notably reduced. Moreover,\nthe non-linearity enhances the back-flow of spins into the ferromagnet and its\ndetrimental effect on the injected spin current, and the contact resistance\nrequired to avoid back-flow is larger than for linear transport. It is also\nshown that by virtue of the non-linearity, a non-magnetic metal contact can be\nused to electrically detect spin accumulation in a semiconductor.",
        "positive": "Dephasing in strongly anisotropic black phosphorus: Weak localization was observed and determined in a black phosphorus (bP)\nfield-effect transistor 65 nm thick. The weak localization behaviour was found\nto be in excellent agreement with the Hikami-Larkin-Nagaoka model for fields up\nto 1~T, from which characteristic scattering lengths could be inferred. The\ndephasing length $L_\\phi$ was found to increase linearly with increasing hole\ndensity attaining a maximum value of 55 nm at a hole density of approximately\n$10^{13} cm^{-2}$ inferred from the Hall effect. The temperature dependence of\n$L_\\phi$ was also investigated and above 1~K, it was found to decrease weaker\nthan the $L_\\phi \\propto T^{-\\frac{1}{2}}$ dependence characteristic of\nelectron-electron scattering in the presence of elastic scattering in two\ndimensions. Rather, the observed power law was found to be close to that\nobserved previously in other quasi-one-dimensional systems such as metallic\nnanowires and carbon nanotubes. We attribute our result to the crystal\nstructure of bP which host a `puckered' honeycomb lattice forming a strongly\nanisotropic medium"
    },
    {
        "anchor": "Conductance through geometrically frustrated itinerant electronic\n  systems: We study a two terminal electronic conductance through an AB$_2$ ring which\nis an example of the family of itinerant geometrically frustrated electronic\nsystems. These systems are characterized by the existence of localized states\nwith nodes in the probability density. We show that such states lead to\ndistinct features in the conductance. For zero magnetic flux, the localized\nstates act as a filter of the zero frequency conductance peak, if the contact\nsites have hopping probability to sites which are not nodes of the localized\nstates. For finite flux, and in a chosen orthonormal basis, the localized\nstates have extensions ranging from two unit cells to the complete ring, except\nfor very particular values of magnetic flux. The conductance exhibits a zero\nfrequency peak with a dip which is a distinct fingerprint of the variable\nextension of these localized states.",
        "positive": "Unified Theory of Magnetoelastic Effects in B20 chiral magnets: A magnetic skyrmion is a spin whirl with topological protection and high\nmobility to electric current. Intrinsic magnetoelastic coupling in chiral\nmagnets permits manipulation of magnetic skyrmions and their lattice using\nmechanical loads, which is essential for developing future spintronics devices.\nIt is found in experiments that the stability and deformation of skyrmions are\nsensitive to stresses, while the appearance of magnetic skyrmions in turn has a\nsignificant effect on the mechanical properties of the underlying material.\nHowever, a theory which explains these related phenomena within a unified\nframework is not seen. Here we construct a thermodynamic model for B20\nhelimagnets incorporating a magnetoelastic functional with necessary higher\norder interactions derived by group theory. Within the model, we establish the\nmethodology to calculate the phase diagram and equilibrium properties of\nhelimagnets under coupled temperature-magneto-elastic field. Applying the model\nto bulk MnSi, we calculate the temperature-magnetic field phase diagram under\nstress-free condition and its variation when uniaxial compression is applied.\nWe also calculate the variation of all the elastic constants with magnetic\nfield. The results obtained agree quantitatively with corresponding\nexperiments. Our model provides a reliable basis for further theoretical\nstudies concerning any magnetoelastic related phenomena in chiral magnets."
    },
    {
        "anchor": "Thermodynamic and quantum bounds on nonlinear DC thermoelectric\n  transport: I consider the non-equilibrium DC transport of electrons through a quantum\nsystem with a thermoelectric response. This system may be any nanostructure or\nmolecule modeled by the nonlinear scattering theory which includes Hartree-like\nelectrostatic interactions exactly, and certain dynamic interaction effects\n(decoherence and relaxation) phenomenologically. This theory is believed to be\na reasonable model when single-electron charging effects are negligible. I\nderive three fundamental bounds for such quantum systems coupled to multiple\nmacroscopic reservoirs, one of which may be superconducting. These bounds\naffect nonlinear heating (such as Joule heating), work and entropy production.\nTwo bounds correspond to the first law and second law of thermodynamics in\nclassical physics. The third bound is quantum (wavelength dependent), and is as\nimportant as the thermodynamic ones in limiting the capabilities of mesoscopic\nheat-engines and refrigerators. The quantum bound also leads to Nernst's\nunattainability principle that the quantum system cannot cool a reservoir to\nabsolute zero in a finite time, although it can get exponentially close.",
        "positive": "Theory of non-equilibrium electronic Mach-Zehnder interferometer: We develop a theoretical description of interaction-induced phenomena in an\nelectronic Mach-Zehnder interferometer formed by integer quantum Hall edge\nstates (with \\nu =1 and 2 channels) out of equilibrium. Using the\nnon-equilibrium functional bosonization framework, we derive an effective\naction which contains all the physics of the problem. We apply the theory to\nthe model of a short-range interaction and to a more realistic case of\nlong-range Coulomb interaction. The theory takes into account\ninteraction-induced effects of dispersion of plasmons, charging, and\ndecoherence. In the case of long-range interaction we find a good agreement\nbetween our theoretical results for the visibility of Aharonov-Bohm\noscillations and experimental data."
    },
    {
        "anchor": "Spin-polarized voltage probes for helical edge state: a model study: Theoretical models of a spin-polarized voltage probe (SPVP) tunnel-coupled to\nthe helical edge states (HES) of a quantum spin Hall system (QSHS) are studied.\nOur first model of the SPVP comprises $N_{P}$ spin-polarized modes (subprobes),\neach of which is locally tunnel-coupled to the HES, while the SPVP, as a whole,\nis subjected to a self-consistency condition ensuring zero average current on\nthe probe. We carry out a numerical analysis which shows that the optimal\nsituation for reading off spin-resolved voltage from the HES depends on the\ninterplay of the probe-edge tunnel-coupling and the number of modes in the\nprobe ($N_P$). We further investigate the stability of our findings by\nintroducing Gaussian fluctuations in {\\it{(i)}} the tunnel-coupling between the\nsubprobes and the HES about a chosen average value and {\\it{(ii)}}\nspin-polarization of the subprobes about a chosen direction of the net\npolarization of SPVP. We also perform a numerical analysis corresponding to the\nsituation where four such SPVPs are implemented in a self-consistent fashion\nacross a ferromagnetic barrier on the HES and demonstrate that this model\nfacilitates the measurements of spin-resolved four-probe voltage drops across\nthe ferromagnetic barrier. As a second model, we employ the edge state of a\nquantum anomalous Hall state (QAHS) as the SPVP which is tunnel-coupled over an\nextended region with the HES. A two-dimensional lattice simulation for the\nquantum transport of the proposed device setup comprising a junction of QSHS\nand QAHS is considered and a feasibility study of using the edge of the QAHS as\nan efficient spin-polarized voltage probe is carried out in presence of an\noptimal strength of the disorder.",
        "positive": "Zero-frequency anomaly in quasiclassical ac transport: Memory effects in\n  a two-dimensional metal with a long-range random potential or random magnetic\n  field: We study the low-frequency behavior of the {\\it ac} conductivity\n$\\sigma(\\omega)$ of a two-dimensional fermion gas subject to a smooth random\npotential (RP) or random magnetic field (RMF). We find a non-analytic\n$\\propto|\\omega|$ correction to ${\\rm Re} \\sigma$, which corresponds to a\n$1/t^2$ long-time tail in the velocity correlation function. This contribution\nis induced by return processes neglected in Boltzmann transport theory. The\nprefactor of this $|\\omega|$-term is positive and proportional to $(d/l)^2$ for\nRP, while it is of opposite sign and proportional to $d/l$ in the weak RMF\ncase, where $l$ is the mean free path and $d$ the disorder correlation length.\nThis non-analytic correction also exists in the strong RMF regime, when the\ntransport is of a percolating nature. The analytical results are supported and\ncomplemented by numerical simulations."
    },
    {
        "anchor": "Emergent metallicity at the grain boundaries of higher-order topological\n  insulators: Topological lattice defects, such as dislocations and grain boundaries (GBs),\nare ubiquitously present in the bulk of quantum materials and externally\ntunable in metamaterials. In terms of robust modes, localized near the defect\ncores, they are instrumental in identifying topological crystals, featuring the\nhallmark band inversion at a finite momentum (translationally active type).\nHere we show that GB superlattices in both two-dimensional and\nthree-dimensional translationally active higher-order topological insulators\nharbor a myriad of dispersive modes that are typically placed at finite\nenergies, but always well-separated from the bulk states. However, when the\nBurgers vector of the constituting edge dislocations points toward the gapless\ncorners or hinges, both second-order and third-order topological insulators\naccommodate self-organized emergent topological metals near the zero energy\n(half-filling) in the GB mini Brillouin zone. We discuss possible material\nplatforms where our proposed scenarios can be realized through the\nband-structure and defect engineering.",
        "positive": "Hidden-symmetry-protected Z_2 topological insulator in a cubic lattice: Usually $Z_2$ topological insulators are protected by time reversal symmetry.\nHere, we present a new type of $Z_2$ topological insulators in a cubic lattice\nwhich is protected by a novel hidden symmetry, while time reversal symmetry is\nbroken. The hidden symmetry has a composite antiunitary operator consisting of\nfractional translation, complex conjugation, sublattice exchange, and local\ngauge transformation. Based on the hidden symmetry, we define the\nhidden-symmetry polarization and $Z_2$ topological invariant to characterize\nthe topological insulators. The surface states have band structures with odd\nnumber of Dirac cones, where pseudospin-momentum locking occurs. When the\nhidden-symmetry-breaking perturbations are added on the boundaries, a gap opens\nin the surface band structure, which confirms that the topological insulator\nand the surface states are protected by the hidden symmetry. We aslo discuss\nthe realization and detection of this new kind of $Z_2$ topological insulator\nin optical lattices with ultracold atom techniques."
    },
    {
        "anchor": "Magnetic Interaction between Surface Engineered Rare-earth Atomic Spins: We report the ab initio study of rare-earth adatoms (Gd) on an insulating\nsurface. This surface is of interest because of previous studies by scanning\ntunneling microscopy showing spin excitations of transition metal adatoms. The\npresent work is the first study of rare-earth spin-coupled adatoms, as well as\nthe geometry effect of spin coupling, and the underlying mechanism of\nferromagnetic coupling. The exchange coupling between Gd atoms on the surface\nis calculated to be antiferromagnetic in a linear geometry and ferromagnetic in\na diagonal geometry, by considering their collinear spins and using the PBE+U\nexchange correlation. We also find the Gd dimers in these two geometries are\nsimilar to the nearest-neighbor (NN) and the next-NN Gd atoms in GdN bulk. We\nanalyze how much direct exchange, superexchange, and RKKY interactions\ncontribute to the exchange coupling for both geometries by additional\nfirst-principles calculations of related model systems.",
        "positive": "Novel Magnetic Quantization of sp$^{3}$ Bonding in Monolayer Tinene: A generalized tight-binding model, which is based on the subenvelope\nfunctions of the different sublattices, is developed to explore the novel\nmagnetic quantization in monolayer gray tin. The effects due to the $sp^{3}$\nbonding, the spin-orbital coupling, the magnetic field and the electric field\nare simultaneously taken into consideration. The unique magneto-electronic\nproperties lie in two groups of low-lying Landau levels, with different orbital\ncomponents, localization centers, state degeneracy, spin configurations, and\nmagnetic- and electric-field dependences. The first and second groups mainly\ncome from the $5p_{z}$ and ($5p_{x}$,$5p_{y}$) orbitals, respectively. Their\nLandau-level splittings are, respectively, induced by the electric field and\nspin-orbital interactions. The intragroup anti-crossings are only revealed in\nthe former. The unique tinene Landau levels are absent in graphene, silicene\nand germanene."
    },
    {
        "anchor": "Dephasing of Electrons on Helium by Collisions with Gas Atoms: The damping of quantum effects in the transport properties of electrons\ndeposited on a surface of liquid helium is studied. It is found that due to\nvertical motion of the helium vapour atoms the interference of paths of\nduration $t$ is damped by a factor $\\exp - (t/\\tau_v)^3$. An expression is\nderived for the weak-localization lineshape in the case that damping occurs by\na combination of processes with this type of cubic exponential damping and\nprocesses with a simple exponential damping factor.",
        "positive": "Sharp correlations in the ARPES spectra of strongly disordered\n  topological boundary modes: Data from angle resolved photo-emission spectroscopy (ARPES) often serves as\na smoking-gun evidence for the existence of topological materials. It provides\nthe energy dispersion curves of the topological boundary modes which\ncharacterize these phases. Unfortunately this method requires a sufficiently\nregular boundary such that these boundary modes remain sharp in momentum space.\nHere the seemingly random data obtained from performing ARPES on strongly\ndisordered topological insulators and Weyl semimetals is analyzed theoretically\nand numerically. Expectedly the disorder averaged ARPES spectra appear\nfeatureless. Surprisingly however, correlations in these spectra between\ndifferent energies and momenta reveal delta-sharp features in momentum space.\nMeasuring such correlations using nano-ARPES may verify the topological nature\nof the suggested weak topological insulator ($Bi_{14} Rh_3 I_9$) which thus far\nwas not studied using ARPES due to the rough nature of its metallic surfaces."
    },
    {
        "anchor": "Laser Annealed Two Dimensional SiO2/Si1-xGex Scaffolds for Nanoscaled\n  Devices, Synergy of Experiment and Computation: Ultraviolet nanosecond laser annealing (UV-NLA) proves to be an important\ntechnique, particularly when tightly controlled heating and melting are\nnecessary. In the realm of semiconductor technologies, the significance of\nlaser annealing (NLA) grows in tandem with the escalating intricacy of\nintegration schemes in nano-scaled devices. Silicon-germanium alloys have been\nstudied for decades for their compatibility with silicon devices. Indeed, they\nenable the manipulation of properties like strain, carrier mobilities and\nbandgap. Laser melting on such type of layers, however results, up to now, in\nthe development of extended defects and poor control over layer morphology. In\nour study, we investigate the laser melting of ~700 nm thick relaxed\nsilicon-germanium samples coated with SiO2 nano-arrays, achieving a precise\ncontrol of the melting process, without observing the formation of extended\ndefects at the interface left by the liquid front. We found the geometrical\nparameters of the silicon oxide having an impact on the thermal budget samples\nsee, influencing melt threshold, melt depth and germanium distribution.",
        "positive": "Dynamical spin-to-charge conversion on the edge of quantum spin Hall\n  insulator: We theoretically manifest that the edge of a quantum spin Hall insulator\n(QSHI), attached to an insulating ferromagnet (FM), can realize a highly\nefficient spin-to-charge conversion. Based on a one-dimensional QSHI-FM\njunction, the electron dynamics on the QSHI edge is analyzed, driven by a\nmagnetization dynamics in the FM. Under a large gap opening on the edge from\nthe magnetic exchange coupling, we find that the spin injection into the QSHI\nedge gets suppressed while the charge current driven on the edge gets\nmaximized, demanded by the band topology of the one-dimensional helical edge\nstates."
    },
    {
        "anchor": "Orbital eigenchannel analysis for ab-initio quantum transport\n  calculations: We show how to extract the orbital contribution to the transport\neigenchannels from a first-principles quantum transport calculation in a\nnanoscopic conductor. This is achieved by calculating and diagonalizing the\nfirst-principles transmission matrix reduced to selected scattering\ncross-sections. As an example, the orbital nature of the eigenchannels in the\ncase of Ni nanocontacts is explored, stressing the difficulties inherent to the\nuse of non-orthogonal basis sets and first-principles Hamiltonians.",
        "positive": "Quantum Spin Hall Effect in Two-dimensional Crystals of Transition Metal\n  Dichalcogenides: We propose to engineer time-reversal-invariant topological insulators in\ntwo-dimensional (2D) crystals of transition metal dichalcogenides (TMDCs). We\nnote that, at low doping, semiconducting TMDCs under shear strain will develop\nspin-polarized Landau levels residing in different valleys. We argue that gaps\nbetween Landau levels in the range of $10-100$ Kelvin are within experimental\nreach. In addition, we point out that a superlattice arising from a Moir\\'e\npattern can lead to topologically non-trivial subbands. As a result, the edge\ntransport becomes quantized, which can be probed in multi-terminal devices made\nusing strained 2D crystals and/or heterostructures. The strong $d$ character of\nvalence and conduction bands may also allow for the investigation of the\neffects of electron correlations on the topological phases."
    },
    {
        "anchor": "Graphene field-effect transistors for sensing ion-channel coupled\n  receptors: towards biohybrid nanoelectronics for chemical detection: Graphene field effect transistors (G-FETs) have appeared as suitable\ncandidates for sensing charges and have thus attracted large interest for ion\nand chemical detections. In particular, their high sensitivity, chemical\nrobustness, transparency and bendability offer a unique combination for\ninterfacing living and soft matters. Here we have demonstrated their ability to\nsense targeted biomolecules, by combining them with ion channels-coupled\nreceptors (ICCRs). These receptors have been naturally or artificially\nexpressed within living cell membranes to generate ion fluxes in presence of\nchemicals of interest. Here, we have successfully combined those biosensors\nwith G-FET array which converts the bio-activation of the ICCRs into readable\nelectronic signals. This hybrid bioelectronic device leverages the advantages\nof the biological receptor and the graphene field effect transistor enabling\nthe selective detection of biomolecules, which is a current shortcoming of\nelectronic sensors. Additionally, the G-FET allows to discriminate the polarity\nof the ion fluxes which otherwise remains hidden from conventional\nelectrophysiological recordings. The multisite recording ability offered by the\nG-FET array rises numerous possibilities for multiscale sensing and high\nthroughput screening of cellular solutions or analytes, which is of both\nfundamental and applied interests in health and environment monitoring.",
        "positive": "Atomistic simulation of the electronic states of adatoms in monolayer\n  MoS2: Using an ab initio density functional theory (DFT) based electronic structure\nmethod, we study the effects of adatoms on the electronic properties of\nmonolayer transition metal dichalcogenide (TMD) Molybdenum-disulfide (MoS2). We\nconsider the 1st (Li, Na, K) and 7th (F, Cl, Br) column atoms and metals (Sc,\nTi, Ta, Mo, Pd, Pt, Ag, Au). Three high symmetry sites for the adatom on the\nsurface of monolayer MoS2 are examined as starting points to search for the\nmost energetically stable configuration for each adatom-monolayer MoS2 system,\nas well as the type of associated bonding. For the most stable adatom\npositions, we characterize the emergence of adatom-induced electronic states\nincluding any dopant states."
    },
    {
        "anchor": "Atomistic Simulation of Phonon and Magnon Thermal Transport across the\n  Ferro-Paramagnetic Transition: A temperature-dependent approach involving Green-Kubo equilibrium atomic and\nspin dynamics (GKEASD) is reported to assess phonon and magnon thermal\ntransport processes accounting for phonon-magnon interactions. Using\nbody-center cubic (BCC) iron as a case study, GKEASD successfully reproduces\nits characteristic temperature-dependent spiral and lattice thermal\nconductivities. The non-electronic thermal conductivity, i.e., the sum of\nphonon and magnon thermal conductivities, calculated using GKEASD for BCC Fe\nagrees well with experimental measurements. Spectral energy analysis reveals\nthat high-frequency phonon-magnon scattering rates are one order of magnitude\nlarger than those at low frequencies due to energy scattering conservation\nrules and high densities of states. Higher temperatures further accentuate this\nphenomenon. This new framework fills existing gaps in simulating thermal\ntransport across the ferro- to para-magnetic transition. Future application of\nthis methodology to phonon- and magnon-dominant insulators and semiconductors\nwill enhance understanding of emerging thermoelectric, spin caloritronic and\nsuperconducting materials.",
        "positive": "Atomic Response in the Near-field of Nanostructured Plasmonic\n  Metamaterial: We report on reflection spectra of caesium atoms in close vicinity of a\nnanostructured metallic meta-surface. We show that the hyperfine sub-Doppler\nspectrum of the $6S_{1/2} - 6P_{3/2}$ resonance transition at 852 nm is\nstrongly affected by the coupling to the plasmonic resonance of the\nnanostructure. Fine tuning of dispersion and positions of the atomic lines in\nthe near-field of plasmonic metamaterials could have uses and implications for\nthe atom-based metrology, sensing and the development of atom-on-a-chip\ndevices."
    },
    {
        "anchor": "Quantum orientational melting of mesoscopic clusters: By path integral Monte Carlo simulations we study the phase diagram of two -\ndimensional mesoscopic clusters formed by electrons in a semiconductor quantum\ndot or by indirect magnetoexcitons in double quantum dots. At zero (or\nsufficiently small) temperature, as quantum fluctuations of particles increase,\ntwo types of quantum disordering phenomena take place: first, at small values\nof quantum de Boer parameter q < 0.01 one can observe a transition from a\ncompletely ordered state to that in which different shells of the cluster,\nbeing internally ordered, are orientationally disordered relative to each\nother. At much greater strengths of quantum fluctuations, at q=0.1, the\ntransition to a disordered (superfluid for the boson system) state takes place.",
        "positive": "A generalized model of the noise spectrum of a two-level fluctuator in\n  the presence of an electron subbath: The work of Ahn derives the noise power spectrum of a two-level fluctuator\n(TLF) in the case that it interacts only with a subregion of a full electron\nbath and thus is subject to a fluctuating temperature. However, Eq.~(1), which\ngives the variance of the subbath temperature in terms of the heat capacity, in\nthat work carries the implicit assumption that the heat capacity of this\nsubbath may be taken to be a constant, which is a good approximation at higher\ntemperatures, but breaks down at lower temperatures. We thus extend this work\nto the case in which the fact that the electronic heat capacity of a\ntwo-dimensional electron gas (2DEG) $C_V\\propto T$, rather than constant in\ntemperature, is fully taken into account. We show that, at low temperatures,\nthe resulting power spectrum of the noise $S(\\omega)\\propto e^{-C/T^{3/8}}$, in\ncontrast to $S(\\omega)\\propto e^{-C'/T^{1/3}}$ as found previously, where $C$\nand $C'$ are constants. We also compare the numerical results that one would\nobtain from the two models and find that our results for $S(\\omega)$ can differ\nfrom those of Ahn by several orders of magnitude at low temperatures."
    },
    {
        "anchor": "Charge and Spin Reconstruction in Quantum Hall Strips: We study the effect of electron-electron interactions on the charge and spin\nstructures of a Quantum Hall strip in a triangularly confined potential. We\nfind that the strip undergoes a spin-unpolarized to spin-polarized transition\nas a function of magnetic field perpendicular to the strip. For sharp\nconfinements the spin-polarization transition is spontaneous and first develops\nat the softer side of the triangular potential which shows up as an\n\"eye-structure\" in the electron dispersion. For sufficiently weak confinements\nthis spin-polarization transition is preceded by a charge reconstruction of a\nsingle spin species, which creates a spin-polarized strip of electrons with a\nwidth of the order of the magnetic length detached from the rest of the system.\nRelevance of our findings to the recent momentum resolved tunneling experiments\nis also discussed.",
        "positive": "Hot Charge Transfer States and Charge Generation in Donor Acceptor\n  Blends: In an organic blend the vibrational normal mode excited by exciton splitting\nis the same as the one coupled to charge hopping. Excess driving force for\nexciton splitting can therefore aid charge transfer, if vibrational relaxation\nis slow compared to charge transfer. A model is developed that takes this into\naccount and hence explains the experimentally observed relation of driving\nforce for exciton splitting and charge yield and that high charge yields can be\nachieved with the observed fast rates of recombination."
    },
    {
        "anchor": "Universal chiral quasi-steady states in periodically driven many-body\n  systems: We investigate many-body dynamics in a one-dimensional interacting\nperiodically driven system, based on a partially filled version of Thouless's\ntopologically quantized adiabatic pump. The corresponding single-particle\nFloquet bands are chiral, with the Floquet spectrum realizing nontrivial cycles\naround the quasienergy Brillouin zone. For generic filling, with either bosons\nor fermions, the system is gapless and is expected to rapidly absorb energy\nfrom the driving field. We identify parameter regimes where scattering between\nFloquet bands of opposite chirality is exponentially suppressed, opening a long\ntime window in which the system prethermalizes to an infinite-temperature state\nrestricted to a single Floquet band. In this quasi-steady state, the\ntime-averaged current takes a universal value determined solely by the density\nof particles and the topological winding number of the populated Floquet band.\nThis remarkable behavior may be readily studied experimentally in recently\ndeveloped cold atom systems.",
        "positive": "Quantum-size effects on chemisorption properties: CO on Cu ultrathin\n  films: We address, by means of ab-initio calculations, the origin of the correlation\nthat has been observed experimentally between the chemisorption energy of CO on\nnanoscale Cu(001) supported films and quantum-size effects. The calculated\nchemisorption energy shows systematic oscillations, as a function of film\nthickness, with a periodicity corresponding to that of quantum-well states at\nthe surface-Brillouin-zone center crossing the Fermi energy. We explain this\ntrend based on the oscillations, with film thickness, of the decay length on\nthe vacuum side of the quantum-well states at the Fermi energy. Contrary to\nprevious suggestions, we find that the actual oscillations with film thickness\nof the density of states per atom of the film at the Fermi energy cannot\naccount for the observed trend in the chemisorption energy."
    },
    {
        "anchor": "Excitation of localized condensates in the flat band of\n  exciton-polariton Lieb lattice: We propose a way to directly excite compact localized condensates in a nearly\nflat band of the exciton-polariton Lieb lattice by short Laguerre-Gaussian\npulses and investigate the dynamics of these condensates in the presence of\nrepulsive polariton-polariton interaction and distributed losses in the\nlattice. The evolution of a low-density compact polariton condensate shows fast\nRabi oscillations between its excitonic and photonic components, with slow\nbeatings of the Rabi oscillation amplitude. Both oscillations and beatings are\nsuppressed at higher condensate densities due to polariton-polariton repulsion\nand distributed losses in the lattice. A background incoherent pumping can be\nused to increase the lifetime and stability of compact localized states",
        "positive": "Stepwise quantized surface states and delayed Landau level hybridization\n  in Co cluster-decorated BiSbTeSe2 topological insulator devices: In three-dimensional topological insulators (TIs), the nontrivial topology in\ntheir electronic bands casts a gapless state on their solid surfaces, using\nwhich dissipationless TI edge devices based on the quantum anomalous Hall (QAH)\neffect and quantum Hall (QH) effect have been demonstrated. Practical TI\ndevices present a pair of parallel-transport topological surface states (TSSs)\non their top and bottom surfaces. However, due to the no-go theorem, the two\nTSSs always appear as a pair and are expected to quantize synchronously.\nQuantized transport of a separate Dirac channel is still desirable, but has\nnever been observed in graphene even after intense investigation over a period\nof 13 years, with the potential aim of half-QHE. By depositing Co atomic\nclusters, we achieved stepwise quantization of the top and bottom surfaces in\nBiSbTeSe2 (BSTS) TI devices. Renormalization group flow diagrams13, 22 (RGFDs)\nreveal two sets of converging points (CVPs) in the (Gxy, Gxx) space, where the\ntop surface travels along an anomalous quantization trajectory while the bottom\nsurface retains 1/2 e2/h. This results from delayed Landau-level (LL)\nhybridization (DLLH) due to coupling between Co clusters and TSS Fermions."
    },
    {
        "anchor": "Anomalous behavior of the electronic structure of\n  (Bi$_{1-x}$In$_x$)$_2$Se$_3$ across the quantum-phase transition from\n  topological to trivial insulator: Using spin- and angle-resolved spectroscopy and relativistic many-body\ncalculations, we investigate the evolution of the electronic structure of\n(Bi$_{1-x}$In$_x$)$_2$Se$_3$ bulk single crystals around the critical point of\nthe trivial to topological insulator quantum-phase transition. By increasing\n$x$, we observe how a surface gap opens at the Dirac point of the initially\ngapless topological surface state of Bi$_2$Se$_3$, leading to the existence of\nmassive fermions. The surface gap monotonically increases for a wide range of\n$x$ values across the topological and trivial sides of the quantum-phase\ntransition. By means of photon-energy dependent measurements, we demonstrate\nthat the gapped surface state survives the inversion of the bulk bands which\noccurs at a critical point near $x=0.055$. The surface state exhibits a\nnon-zero in-plane spin polarization which decays exponentially with increasing\n$x$, and that persists on both the topological and trivial insulator phases.\nIts out-of-plane spin polarization remains zero demonstrating the absence of a\nhedgehog spin texture expected from broken time-reversal symmetry. Our\ncalculations reveal qualitative agreement with the experimental results all\nacross the quantum-phase transition upon the systematic variation of the\nspin-orbit coupling strength. A non-time reversal symmetry breaking mechanism\nof bulk-mediated scattering processes that increase with decreasing spin-orbit\ncoupling strength is proposed as explanation.",
        "positive": "Tunable Non-local Spin Control in a Coupled Quantum Dot System: The effective interaction between magnetic impurities in metals that can lead\nto various magnetic ground states often competes with a tendency for electrons\nnear impurities to screen the local moment (Kondo effect). The simplest system\nexhibiting the richness of this competition, the two-impurity Kondo system, is\nhere realized experimentally in the form of two quantum dots coupled through an\nopen conducting region. We demonstrate non-local spin control by suppressing\nand splitting Kondo resonances in one quantum dot by changing electron number\nand coupling of the other dot. Results suggest an approach to non-local spin\ncontrol relevant to quantum information processing."
    },
    {
        "anchor": "Theory of integer quantum Hall polaritons in graphene: We present a theory of the cavity quantum electrodynamics of the graphene\ncyclotron resonance. By employing a canonical transformation, we derive an\neffective Hamiltonian for the system comprised of two neighboring Landau levels\ndressed by the cavity electromagnetic field (integer quantum Hall polaritons).\nThis generalized Dicke Hamiltonian, which contains terms that are quadratic in\nthe electromagnetic field and respects gauge invariance, is then used to\ncalculate thermodynamic properties of the quantum Hall polariton system.\nFinally, we demonstrate that the generalized Dicke description fails when the\ngraphene sheet is heavily doped, i.e. when the Landau level spectrum of 2D\nmassless Dirac fermions is approximately harmonic. In this case we `integrate\nout' the Landau levels in valence band and obtain an effective Hamiltonian for\nthe entire stack of Landau levels in conduction band, as dressed by strong\nlight-matter interactions.",
        "positive": "Finite momentum condensation in a pumped microcavity: We calculate the absorption spectra of a semiconductor microcavity into which\na non-equilibrium exciton population has been pumped. We predict strong peaks\nin the spectrum corresponding to collective modes analogous to the Cooper modes\nin superconductors and fermionic atomic gases. These modes can become unstable,\nleading to the formation of off-equilibrium quantum condensates. We calculate a\nphase diagram for condensation, and show that the dominant instabilities can be\nat a finite momentum. Thus we predict the formation of inhomogeneous\ncondensates, similar to Fulde-Ferrel-Larkin-Ovchinnikov states."
    },
    {
        "anchor": "Hot electrons in low-dimensional phonon systems: A simple bulk model of electron-phonon coupling in metals has been\nsurprisingly successful in explaining experiments on metal films that actually\ninvolve surface- or other low-dimensional phonons. However, by an exact\napplication of this standard model to a semi-infinite substrate with a free\nsurface, making use of the actual vibrational modes of the substrate, we show\nthat such agreement is fortuitous, and that the model actually predicts a\nlow-temperature crossover from the familiar T^5 temperature dependence to a\nstronger T^6 log T scaling. Comparison with existing experiments suggests a\nwidespread breakdown of the standard model of electron-phonon thermalization in\nmetals.",
        "positive": "Spin-dependent photogalvanic effects (A Review): In this paper we review both theoretical and experimental studies on\nspin-related photogalvanic effects. A short phenomenological introduction is\nfollowed by the discussion of the circular photogalvanic effect, the direct and\ninverse spin-galvanic effects and the trembling motion of spin-polarized\nelectrons. Then we consider the pure spin currents and magneto-gyrotropic\nphotocurrents. Finally, we discuss the spin-dependent photocurrents in\ntopological insulators and Weyl semimetals."
    },
    {
        "anchor": "Chirality inversion and radius blow-up of a N\u00e9el-type skyrmion by a\n  Pearl vortex: We develop a theory for the coaxial configuration of a N\\'eel-type skyrmion\nand a Pearl vortex in thin superconductor-chiral ferromagnetic\nheterostructures. Using direct numerical solution of the Euler-Lagrange\nequation and micromagnetic simulations we demonstrate that the inhomogeneous\nmagnetic field of the Pearl vortex significantly modifies the skyrmion profile\nwith respect to the one in the absence of the vortex. We discover drastic\nenlargement of the skyrmion's radius and inversion of the skyrmion's chirality.\nTo unravel physics behind these effects we invent novel two-parameter ansatz\nfor the magnetization profile of the skyrmion in the presence of the vortex.\nChirality inversion and radius blow-up are controlled not only by the material\nparameters of the heterostructure but also by the thickness of the\nsuperconductor. Our findings can have implications for Majorana modes localized\nat skyrmion-vortex pairs.",
        "positive": "Spin-dependent scattering in a silicon transistor: The scattering of conduction electrons off neutral donors depends sensitively\non the relative orientation of their spin states. We present a theory of\nspin-dependent scattering in the two dimensional electron gas (2DEG) of field\neffect transistors. Our theory shows that the scattering mechanism is dominated\nby virtual transitions to negatively ionized donor levels. This effect\ntranslates into a source-drain current that always gets reduced when donor\nspins are at resonance with a strong microwave field. We propose a model for\ndonor impurities interacting with conduction electrons in a silicon transistor,\nand compare our explicit numerical calculations to electrically detected\nmagnetic resonance (EDMR) experiments. Remarkably, we show that EDMR is optimal\nfor donors placed into a sweet spot located at a narrow depth window quite far\nfrom the 2DEG interface. This allows significant optimization of spin signal\nintensity for the minimal number of donors placed into the sweet spot, enabling\nthe development of single spin readout devices. Our theory reveals an\ninteresting dependence on conduction electron spin polarization p_c. As p_c\nincreases upon spin injection, the EDMR amplitude first increases as p_{c}^{2},\nand then saturates when a polarization threshold p_T is reached. These results\nshow that it is possible to use EDMR as an in-situ probe of carrier spin\npolarization in silicon and other materials with weak spin-orbit coupling."
    },
    {
        "anchor": "Magnetic impurities on the surface of a topological insulator: The surface states of a topological insulator are described by an emergent\nrelativistic massless Dirac equation in 2+1 dimensions. In contrast to\ngraphene, there is an odd number of Dirac points, and the electron spin is\ndirectly coupled to the momentum. We show that a magnetic impurity opens up a\nlocal gap and suppresses the local density of states. Furthermore, the Dirac\nelectronic states mediate an RKKY interaction among the magnetic impurities\nwhich is always ferromagnetic, whenever the chemical potential lies near the\nDirac point. These effects can be directly measured in STM experiments. We also\nstudy the case of quenched disorder through a renormalization group analysis.",
        "positive": "Detection of long-range orbital-Hall torques: We report and quantify a large orbital-Hall torque generated by Nb and Ru,\nwhich we identify from a strong dependence of torques on the ferromagnets. This\nis manifested as a sign reversal and strong enhancement in the damping-like\ntorques measured in Nb (or Ru)/Ni bilayers as compared to Nb (or Ru)/FeCoB\nbilayers. The long-range nature of orbital transport in the ferromagnet is\nrevealed by the thickness dependences of Ni in Nb (or Ru)/Ni bilayers which are\nmarkedly different from the regular spin absorption in the ferromagnet that\ntakes place within a few angstroms and thus it uniquely distinguishes the\norbital Hall torque from the spin Hall torque."
    },
    {
        "anchor": "Topological phonon polaritons in one-dimensional non-Hermitian\n  nanoparticle chains: Topological phonon polaritons (TPhPs) are highly protected and localized edge\nmodes that are capable of achieving a strong confinement of electromagnetic\nwaves and immune to impurities and disorder. Here we realize TPhPs by\nconstructing one-dimensional dimerized silicon carbide nanoparticle chains,\nwhich mimic the topological property of the well-known Su-Schrieffer-Heeger\n(SSH) model. We analytically calculate the complex band structure of such\nchains by taking all near-field and far-field dipole-dipole interactions into\naccount. For longitudinal modes, we demonstrate that, despite the\nnon-Hermiticity and breaking of the chiral symmetry, the band topology can be\nstill characterized by the complex Zak phase, which is quantized and indicates\na topological phase transition when the dimerization parameter $\\beta$ changes\nfrom less than 0.5 to larger than 0.5, like the conventional Hermitian SSH\nmodel. By calculating the eigenmodes of a finite chain, we find such a\ndimerized chain with $\\beta>0.5$ supports nontrivial topological eigenmodes\nlocalized over both of its edges, indicating the validity of the bulk-boundary\ncorrespondence. On the other hand, for transverse modes, we discover a\ntopological phase transition by increasing the lattice constant, which is due\nto the presence of strong long-range far-field transverse dipole-dipole\ninteractions decaying with the distance $r$ as $1/r$ for an infinitely long\nchain. However, we surprisingly find the emergence of non-Hermitian skin effect\nin a finite chain, which leads to the breakdown of the bulk-boundary\ncorrespondence. Furthermore, by incorporating the effect of localized bulk\neigenmodes and proposing a modified complex Zak phase for a finite lattice, we\nstill recover the topological behavior of the conventional SSH model. We also\ndemonstrate the excitation of topological phonon polaritons and show their\nenhancement to the photonic LDOS.",
        "positive": "Plastic flow of persistent currents in two dimensional strongly\n  interacting systems: The local persistent current in two dimensional strongly interacting systems\nis investigated. As the interaction strength is enhanced the current in the\nsample undergoes a transition from diffusive to ordered flow. The strong\ninteracting flow has the characteristics of a plastic flow through dislocations\nin the pinned charge density wave which develops in the system at low\ndensities."
    },
    {
        "anchor": "Ultrafast creation and melting of nonequilibrium excitonic condensates\n  in bulk WSe$_{2}$: We study the screened dynamics of the nonequilibrium excitonic consensate\nforming in a bulk WSe$_{2}$ when illuminated by coherent light resonant with\nthe lowest-energy exciton. Intervalley scattering causes electron migration\nfrom the optically populated K valley to the conduction band minimum at\n$\\Sigma$. Due to the electron-hole unbalance at the K point a plasma of\nquasi-free holes develops, which efficiently screens the interaction of the\nremaining excitons. We show that this plasma screening causes an ultrafast\nmelting of the nonequilibrium consensate and that during melting coherent\nexcitons and quasi-free electron-hole pairs coexist. The time-resolved spectral\nfunction does exhibit a conduction and excitonic sidebands of opposite\nconvexity and relative spectral weight that changes in time. Both the\ndependence of the time-dependent conduction density on the laser intensity and\nthe time-resolved spectral function agree with recent experiments.",
        "positive": "Strong nonlinear terahertz response induced by Dirac surface states in\n  Bi2Se3 Topological Insulator: Electrons with a linear energy/momentum dispersion are called massless Dirac\nelectrons and represent the low-energy excitations in exotic materials like\nGraphene and Topological Insulators (TIs). Dirac electrons are characterized by\nnotable properties like a high mobility, a tunable density and, in TIs, a\nprotection against backscattering through the spin-momentum looking mechanism.\nAll those properties make Graphene and TIs appealling for plasmonics\napplications. However, Dirac electrons are expected to present also a strong\nnonlinear optical behavior. This should mirror in phenomena like\nelectromagnetic induced transparency (EIT) and harmonic generation. Here, we\ndemonstrate that in Bi2Se3 Topological Insulator, an EIT is achieved under the\napplication of a strong terahertz (THz) electric field. This effect,\nconcomitant determined by harmonic generation and charge-mobility reduction, is\nexclusively related to the presence of Dirac electron at the surface of\nBi2Se_3, and opens the road towards tunable THz nonlinear optical devices based\non Topological Insulator materials."
    },
    {
        "anchor": "A thermodynamic probe of the topological phase transition in epitaxial\n  graphene based Floquet topological insulator: One can use light to tune certain materials, from a trivial to a topological\nphase. A prime example of such materials, classified as Floquet topological\ninsulators (FTI), is epitaxial graphene. In this paper, we probe the\ntopological phase transition of an FTI via the efficiency and work output of\nquantum Otto and quantum Stirling heat engines. A maximum/minimum in the\nefficiency or work output invariably signals the phase transition point.\nFurther, both engines' work output and efficiency are markedly robust against\nthe polarization direction of light.",
        "positive": "Frequency-induced Negative Magnetic Susceptibility in Epoxy/Magnetite\n  Nanocomposites: The epoxy/magnetite nanocomposites express superparamagnetism under a static\nor low-frequency electromagnetic field. At the microwave frequency, said the\nX-band, the nanocomposites reveal an unexpected diamagnetism. To explain the\nintriguing phenomenon, we revisit the Debye relaxation law with the memory\neffect. The magnetization vector of the magnetite is unable to synchronize with\nthe rapidly changing magnetic field, and it contributes to diamagnetism, a\nnegative magnetic susceptibility for nanoparticles. The model just developed\nand the fitting result can not only be used to explain the experimental data in\nthe X-band but also can be used to estimate the transition frequency between\nparamagnetism and diamagnetism."
    },
    {
        "anchor": "Second harmonic generation control in twisted bilayers of transition\n  metal dichalcogenides: The twist angle in transition metal dichalcogenide (TMD) heterobilayers is a\ncompelling degree of freedom that determines electron correlations and the\nperiod of lateral confinement of moir\\'e excitons. Here we perform\npolarization-resolved second harmonic generation (SHG) spectroscopy of\nMoS2/WSe2 heterostructures. We demonstrate that by choosing suitable laser\nenergies the twist angle between two monolayers can be measured directly on the\nassembled heterostructure. We show that the amplitude and polarization of the\nSHG signal from the heterostructure are determined by the twist angle between\nthe layers and exciton resonances at the SH energy. For heterostructures with\nclose to zero twist angle, we observe changes of exciton resonance energies and\nthe appearance of new resonances in the linear and non-linear susceptibilities.",
        "positive": "Modulation of field-like spin orbit torque in heavy metal / ferromagnet\n  heterostructure: Recent studies rediscovered the crucial role of field-like spin orbit torque\n(SOT) in nanosecond-timescale SOT dynamics. However, there is not yet an\neffective way to control its relative amplitude. Here, we experimentally\nmodulate the field-like SOT in W/CoFeB/MgO trilayers through tuning the\ninterfacial spin accumulation. By performing spin Hall magnetoresistance\nmeasurement, we find that the CoFeB with enhanced spin dephasing, either\ngenerated from larger layer thickness or from proper annealing, can distinctly\nboost the spin absorption and enhance the interfacial spin mixing conductance\nG_r. While the damping-like torque efficiency increases with G_r, the\nfield-like torque efficiency turns out to decrease with it. The results suggest\nthat the interfacial spin accumulation, which largely contributes to a\nfield-like torque, is reduced by higher interfacial spin transparency. Our work\nshows a new path to further improve the performance of SOT-based magnetic\ndevices."
    },
    {
        "anchor": "Introduction of spin-orbit interaction into graphene with hydrogenation: Introduction of spin-orbit interaction (SOI) into graphene with weak\nhydrogenation ($\\sim$0.1\\%) by dissociation of hydrogen silsesquioxane resist\nhas been confirmed through the appearance of inverse spin Hall effect. The spin\ncurrent was produced by spin injection from permalloy electrodes excluding\nnon-spin relating experimental artifact.",
        "positive": "Spintronic Quantum Phase Transition in a $Graphene/Pb_{0.24}Sn_{0.76}Te$\n  Heterostructure with Giant Rashba Spin-Orbit Coupling: Mechanical stacking of two dissimilar materials often has surprising\nconsequences for heterostructure behavior. In particular, a two-dimensional\nelectron gas (2DEG) is formed in the heterostructure of the topological\ncrystalline insulator Pb0.24Sn0.76Te and graphene due to contact of a polar\nwith a nonpolar surface and the resulting changes in electronic structure\nneeded to avoid polar catastrophe. We study the spintronic properties of this\nheterostructure with non-local spin valve devices. We observe spin-momentum\nlocking at lower temperatures that transitions to regular spin channel\ntransport only at ~40 K. Hanle spin precession measurements show a spin\nrelaxation time as high as 2.18 ns. Density functional theory calculations\nconfirm that the spin-momentum locking is due to a giant Rashba effect in the\nmaterial and that the phase transition is a Lifshitz transition. The\ntheoretically predicted Lifshitz transition is further evident in the phase\ntransition-like behavior in the Land\\'e g-factor and spin relaxation time."
    },
    {
        "anchor": "Spin echo silencing using a current-biased frequency-tunable resonator: The ability to control microwave emission from a spin ensemble is a\nrequirement of several quantum memory protocols. Here, we demonstrate such\nability by using a resonator whose frequency can be rapidly tuned with a bias\ncurrent. We store excitations in an ensemble of rare-earth-ions and suppress\non-demand the echo emission (`echo silencing') by two methods: 1) detuning the\nresonator during the spin rephasing, and 2) subjecting spins to magnetic field\ngradients generated by the bias current itself. We also show that spin\ncoherence is preserved during silencing.",
        "positive": "Mechanical Properties of Phagraphene Membranes: A Fully Atomistic\n  Molecular Dynamics Investigation: Recently, a new 2D carbon allotrope structure, named phagraphene (PG), was\nproposed. PG has a densely array of penta-hexa-hepta-graphene carbon rings. PG\nwas shown to present low and anisotropic thermal conductivity and it is\nbelieved that this anisotropy should be also reflected in its mechanical\nproperties. Although PG mechanical properties have been investigated, a\ndetailed and comprehensive study is still lacking. In the present work we have\ncarried out fully atomistic reactive molecular dynamics simulations using the\nReaxFF force field, to investigate the mechanical properties and fracture\npatterns of PG membranes. The Young's modulus values of the PG membranes were\nestimated from the stress-strain curves. Our results show that these curves\npresent three distinct regimes: one regime where ripples dominate the structure\nand mechanical properties of the PG membranes; an elastic regime where the\nmembranes exhibit fully planar configurations; and finally a plastic regime\nwhere permanent deformations happened to the PG membrane up to the mechanical\nfailure or fracture."
    },
    {
        "anchor": "Engineering Curvature Induced Anisotropy in Thin Ferromagnetic Films: The large curvature effects on micromagnetic energy of a thin ferromagnetic\nfilm with nonlocal dipolar energy are considered. We predict that the dipolar\ninteraction and surface curvature can produce perpendicular anisotropy which\ncan be controlled by engineering a special type of periodic surface shape\nstructure. Similar effects can be achieved by a significant surface roughness\nin the film. We show that in general the anisotropy can point in an arbitrary\ndirection depending on the surface curvature. We provide simple examples of\nthese periodic surface structures to demonstrate how to engineer particular\nanisotropies in the film.",
        "positive": "Imaginary geometric phases of quantum trajectories: A quantum object can accumulate a geometric phase when it is driven along a\ntrajectory in a parameterized state space with non-trivial gauge structures.\nInherent to quantum evolutions, a system can not only accumulate a quantum\nphase but may also experience dephasing, or quantum diffusion. Here we show\nthat the diffusion of quantum trajectories can also be of geometric nature as\ncharacterized by the imaginary part of the geometric phase. Such an imaginary\ngeometric phase results from the interference of geometric phase dependent\nfluctuations around the quantum trajectory. As a specific example, we study the\nquantum trajectories of the optically excited electron-hole pairs, driven by an\nelliptically polarized terahertz field, in a material with non-zero Berry\ncurvature near the energy band extremes. While the real part of the geometric\nphase leads to the Faraday rotation of the linearly polarized light that\nexcites the electron-hole pair, the imaginary part manifests itself as the\npolarization ellipticity of the terahertz sidebands. This discovery of\ngeometric quantum diffusion extends the concept of geometric phases."
    },
    {
        "anchor": "Weak ferroelectric charge transfer in layer-asymmetric bilayers of 2D\n  semiconductors: In bilayers of two-dimensional (2D) semiconductors with stacking arrangements\nwhich lack inversion symmetry charge transfer between the layers due to\nlayer-asymmetric interband hybridisation can generate a potential difference\nbetween the layers. We analyse bilayers of transition metal dichalcogenides\n(TMDs) - in particular, WSe$_2$ - for which we find a substantial\nstacking-dependent charge transfer, and InSe, for which the charge transfer is\nfound to be negligibly small. The information obtained about TMDs is then used\nto map potentials generated by the interlayer charge transfer across the\nmoir\\'e superlattice in twistronic bilayers.",
        "positive": "Green's Function of Anyons in Calogero Model and Quantum Hydrodynamics: We find that correlation functions at one dimension are crucially affected by\nthe curvature of the bare single particle spectrum. Parabolic curvature leads\nto two closely related phenomena: the Green's function exhibits oscillation (as\na function of the coordinate), while the polarization operator acquires support\nin part of the frequency-momentum plane. We calculated the Green's function\nusing the WKB approximation for collective variables theory\n\\cite{JevickiSakita}. Within this approach, the single particle Green's\nfunction is related to a quantum soliton \\cite{Polychronakos}. The finite\nsupport of the polarization operator is due to periodic density waves."
    },
    {
        "anchor": "Circular polarization dependent study of the microwave photoconductivity\n  in a two-dimensional electron system: The polarization dependence of the low field microwave photoconductivity and\nabsorption of a two-dimensional electron system has been investigated in a\nquasi-optical setup in which linear and any circular polarization can be\nproduced in-situ. The microwave induced resistance oscillations and the zero\nresistance regions are notedly immune to the sense of circular polarization.\nThis observation is discrepant with a number of proposed theories. Deviations\nonly occur near the cyclotron resonance absorption where an unprecedented large\nresistance response is observed.",
        "positive": "Nanomagnetic logic with non-uniform states of clocking: Nanomagnetic logic transmits information along a path of nanomagnets. The\nbasic mechanism to drive such a transmission, known as clocking, can be\nachieved by exploiting the spin-Hall effect, as recently observed in\nexperiments on Ta/CoFeB/MgO multilayers [D. Bhowmik, et al., Nat. Nano. 9, 59\n(2013)]. This paper shows the fundamental mechanism of the spin-Hall driven\nclocking by using a full micromagnetic framework and considering two different\ndevices, Ta/CoFeB/MgO and Pt/CoFeB/MgO. The former is used for a direct\ncomparison of the numerical results with the experiments while the latter\npermits to predict the effect of the Dzyaloshinskii-Moriya interaction (DMI) in\nthe clocking mechanism. Results show that the clocking state is non-uniform and\nit is characterized by the presence of domains separated by Bloch (N\\'eel)\ndomain walls depending on the absence (presence) of the DMI. Our findings point\nout that for the design of nanomagnetic logic a full micromagnetic approach is\nnecessary."
    },
    {
        "anchor": "Quantum Hall Effects with High Spin-Chern Numbers in Buckled Honeycomb\n  Structure with Magnetic Order: As a topological insulator, the quantum Hall (QH) effect is indexed by the\nChern and spin-Chern numbers $\\mathcal{C}$ and $\\mathcal{C}_{\\text{spin}}$. We\nhave only $\\mathcal{C}_{\\text{spin}}=0$ or $\\pm \\frac{1}{2}$ in conventional QH\nsystems. We investigate QH effects in generic monolayer honeycomb systems. We\nsearch for spin-resolved characteristic patterns by exploring Hofstadter's\nbutterfly diagrams in the lattice theory and fan diagrams in the low-energy\nDirac theory. The Chern and spin-Chern numbers are calculated based on the\nbulk-edge correspondence in the lattice theory and on the Kubo formula in the\nDirac theory. It is shown that the spin-Chern number can takes an arbitrary\nhigh value for certain QH systems in coexistence with buckled structure and\nmagnetic order. This is a new type of topological insulators. Samples may be\nprovided by silicene with ferromagnetic order and transition-metal oxide with\nantiferromagnetic order.",
        "positive": "Separation of inverse spin Hall effect and anomalous Nernst effect in\n  ferromagnetic metals: Inverse spin Hall effect (ISHE) in ferromagnetic metals (FM) can also be used\nto detect the spin current generated by longitudinal spin Seebeck effect in a\nferromagnetic insulator YIG. However, anomalous Nernst effect(ANE) in FM itself\nalways mixes in the thermal voltage. In this work, the exchange bias structure\n(NiFe/IrMn)is employed to separate these two effects. The exchange bias\nstructure provides a shift field to NiFe, which can separate the magnetization\nof NiFe from that of YIG in M-H loops. As a result, the ISHE related to\nmagnetization of YIG and the ANE related to the magnetization of NiFe can be\nseparated as well. By comparison with Pt, a relative spin Hall angle of NiFe\n(0.87) is obtained, which results from the partially filled 3d orbits and the\nferromagnetic order. This work puts forward a practical method to use the ISHE\nin ferromagnetic metals towards future spintronic applications."
    },
    {
        "anchor": "Spin-orbit coupling in methyl functionalized graphene: We present first-principles calculations of the electronic band structure and\nspin-orbit effects in graphene functionalized with methyl molecules in dense\nand dilute limits. The dense limit is represented by a 2$\\times$2 graphene\nsupercell functionalized with one methyl admolecule. The calculated spin-orbit\nsplittings are up to $0.6$ meV. The dilute limit is deduced by investigating a\nlarge, 7$\\times$7, supercell with one methyl admolecule. The electronic band\nstructure of this supercell is fitted to a symmetry-derived effective\nHamiltonian, allowing us to extract specific hopping parameters including\nintrinsic, Rashba, and PIA (pseudospin inversion asymmetry) spin-orbit terms.\nThese proximity-induced spin-orbit parameters have magnitudes of about 1 meV,\ngiant compared to pristine graphene whose intrinsic spin-orbit coupling is\nabout 10 $\\mu$eV. We find that the origin of this giant local enhancement is\nthe $sp^3$ corrugation and the breaking of local pseudospin inversion symmetry,\nas in the case of hydrogen adatoms. Also similar to hydrogen, methyl acts as a\nresonant scatterer, with a narrow resonance peak near the charge neutrality\npoint. We also calculate STM-like images showing the local charge densities at\ndifferent energies around methyl on graphene.",
        "positive": "Topological Andreev Rectification: We develop the theory of an Andreev junction, which provides a method to\nprobe the intrinsic topology of the Fermi sea of a two-dimensional electron gas\n(2DEG). An Andreev junction is a Josephson $\\pi$ junction proximitizing a\nballistic 2DEG, and exhibits low-energy Andreev bound states that propagate\n$\\textit{along}$ the junction. It has been shown that measuring the nonlocal\nLandauer conductance due to these Andreev modes in a narrow linear junction\nleads to a topological Andreev rectification (TAR) effect characterized by a\nquantized conductance that is sensitive to the Euler characteristic $\\chi_F$ of\nthe 2DEG Fermi sea. Here we expand on that analysis and consider more realistic\ndevice geometries that go beyond the narrow linear junction and fully adiabatic\nlimits considered earlier. Wider junctions exhibit additional Andreev modes\nthat contribute to the transport and degrade the quantization of the\nconductance. Nonetheless, we show that an appropriately defined\n$\\textit{rectified conductance}$ remains robustly quantized provided large\nmomentum scattering is suppressed. We verify and demonstrate these predictions\nby performing extensive numerical simulations of realistic device geometries.\nWe introduce a simple model system that demonstrates the robustness of the\nrectified conductance for wide linear junctions as well as point contacts, even\nwhen the nonlocal conductance is not quantized. Motivated by recent\nexperimental advances, we model devices in specific materials, including InAs\nquantum wells, as well as monolayer and bilayer graphene. These studies\nindicate that for sufficiently ballistic samples observation of the TAR effect\nshould be within experimental reach."
    },
    {
        "anchor": "Thermal Diffusivity and Viscosity of Suspensions of Disc Shaped\n  Nanoparticles: In this work we conduct a transient heat conduction experiment with an\naqueous suspension of nanoparticle disks of Laponite JS, a sol forming grade,\nusing laser light interferometry. The image sequence in time is used to measure\nthermal diffusivity and thermal conductivity of the suspension. Imaging of the\ntemperature distribution is facilitated by the dependence of refractive index\nof the suspension on temperature itself. We observe that with the addition of 4\nvolume % of nano-disks in water, thermal conductivity of the suspension\nincreases by around 30%. A theoretical model for thermal conductivity of the\nsuspension of anisotropic particles by Fricke as well as by Hamilton and\nCrosser explains the trend of data well. In turn, it estimates thermal\nconductivity of the Laponite nanoparticle itself, which is otherwise difficult\nto measure in a direct manner. We also measure viscosity of the nanoparticle\nsuspension using a concentric cylinder rheometer. Measurements are seen to\nfollow quite well, the theoretical relation for viscosity of suspensions of\noblate particles that includes up to two particle interaction. This result\nrules out the presence of clusters of particles in the suspension. The\neffective viscosity and thermal diffusivity data show that the shape of the\nparticle has a role in determining enhancement of thermophysical properties of\nthe suspension.",
        "positive": "A Double Quantum Dot Spin Valve: A most fundamental and longstanding goal in spintronics is to electrically\ntune highly efficient spin injectors and detectors, preferably compatible with\nnanoscale electronics. Here, we demonstrate all these points using\nsemiconductor quantum dots (QDs), individually spin-polarized by ferromagnetic\nsplit-gates (FSGs). As a proof of principle, we fabricated a double QD spin\nvalve consisting of two weakly coupled semiconducting QDs in an InAs nanowire\n(NW), each with independent FSGs that can be magnetized in parallel or\nanti-parallel. In tunneling magnetoresistance (TMR) experiments at zero\nexternal magnetic field, we find a strongly reduced spin valve conductance for\nthe two anti-parallel configurations, with a single QD polarization of $\\sim\n27\\%$. The TMR can be significantly improved by a small external field and\noptimized gate voltages, which results in a continuously electrically tunable\nTMR between $+80\\%$ and $-90\\%$. A simple model quantitatively reproduces all\nour findings, suggesting a gate tunable QD polarization of $\\pm 80\\%$. Such\nversatile spin-polarized QDs are suitable for various applications, for example\nin spin projection and correlation experiments in a large variety of\nnanoelectronics experiments."
    },
    {
        "anchor": "Going Ballistic: Graphene Hot Electron Transistors: This paper reviews the experimental and theoretical state of the art in\nballistic hot electron transistors that utilize two-dimensional base contacts\nmade from graphene, i.e. graphene base transistors (GBTs). Early performance\npredictions that indicated potential for THz operation still hold true today,\neven with improved models that take non-idealities into account. Experimental\nresults clearly demonstrate the basic functionality, with on/off current\nswitching over several orders of magnitude, but further developments are\nrequired to exploit the full potential of the GBT device family. In particular,\ninterfaces between graphene and semiconductors or dielectrics are far from\nperfect and thus limit experimental device integrity, reliability and\nperformance.",
        "positive": "Dephasing due to quasiparticle tunneling in fluxonium qubits: a\n  phenomenological approach: The fluxonium qubit has arisen as one of the most promising candidate devices\nfor implementing quantum information in superconducting devices, since it is\nboth insensitive to charge noise (like flux qubits) and insensitive to flux\nnoise (like charge qubits). Here, we investigate the stability of the quantum\ninformation to quasiparticle tunneling through a Josephson junction.\nMicroscopically, this dephasing is due to the dependence of the quasiparticle\ntransmission probability on the qubit state. We argue that on a\nphenomenological level the dephasing mechanism can be understood as originating\nfrom heat currents, which are flowing in the device due to possible effective\ntemperature gradients, and their sensitivity to the qubit state. The emerging\ndephasing time is found to be insensitive to the number of junctions with which\nthe superinductance of the fluxonium qubit is realised. Furthermore, we find\nthat the dephasing time increases quadratically with the shunt-inductance of\nthe circuit which highlights the stability of the device to this dephasing\nmechanism."
    },
    {
        "anchor": "Probing Majorana bound states via a pn-junction containing a quantum dot: We propose an alternative route to transport experiments for detecting\nMajorana bound states (MBSs) by combining topological superconductivity with\nquantum optics in a superconducting $pn$ junction containing a quantum dot\n(QD). We consider a topological superconductor (TSC) hosting two Majorana bound\nstates at its boundary ($n$ side). Within an effective low-energy model, the\nMBSs are coherently tunnel-coupled to a spin-split electron level on the QD\nwhich is placed close to one of the MBSs. Holes on the QD are tunnel-coupled to\na normal conducting reservoir ($p$ side). Via electron-hole recombination,\nphotons in the optical range are emitted, which have direct information on the\nMBS-properties through the recombined electrons. Using a master equation\napproach, we calculate the polarization-resolved photon emission intensities\n(PEIs). In the weak coupling regime between MBSs and QD, we find an analytical\nexpression for the PEI which allows to clearly distinguish the cases of well\nseparated MBSs at zero energy from overlapping MBSs. For separated MBSs, the\nMajorana spinor-polarization is given by the relative widths of the two PEI\npeaks associated with the two spin states on the QD. For overlapping MBSs, a\ncoupling to the distant (nonlocal) MBS causes a shift of the emission peaks.\nAdditionally, we show that quasiparticle poisoning (QP) influences the PEI\ndrastically and changes its shot noise from super-Poissonian to sub-Poissonian.\nIn the strong coupling regime, more resonances emerge in the PEI due to\nspin-mixing effects. Finally, we comment on how our proposal could be\nimplemented using a Majorana nanowire.",
        "positive": "Odd and even Kondo effects from emergent localisation in quantum point\n  contacts: A quantum point contact (QPC) is a very basic nano-electronic device: a short\nand narrow transport channel between two electron reservoirs. In clean channels\nelectron transport is ballistic and the conductance $G$ is then quantised as a\nfunction of channel width with plateaus at integer multiples of $2e^2/h$ ($e$\nis the electron charge and $h$ Planck's constant). This can be understood in a\npicture where the electron states are propagating waves, without need to\naccount for electron-electron interactions. Quantised conductance could thus be\nthe signature of ultimate control over nanoscale electron transport. However,\neven studies with the cleanest QPCs generically show significant anomalies on\nthe quantised conductance traces and there is consensus that these result from\nelectron many-body effects. Despite extensive experimental and theoretical\nstudies understanding of these anomalies is an open problem. We report evidence\nthat the many-body effects have their origin in one or more spontaneously\nlocalised states that emerge from Friedel oscillations in the QPC channel.\nKondo physics will then also contribute to the formation of the many-body state\nwith Kondo signatures that reflect the parity of the number of localised\nstates. Evidence comes from experiments with length-tunable QPCs that show a\nperiodic modulation of the many-body physics with Kondo signatures of\nalternating parity. Our results are of importance for assessing the role of\nQPCs in more complex hybrid devices and proposals for spintronic and quantum\ninformation applications. In addition, our results show that tunable QPCs offer\na rich platform for investigating many-body effects in nanoscale systems, with\nthe ability to probe such physics at the level of a single site."
    },
    {
        "anchor": "The $S$-matrix for surface boundary states: an application to\n  photoemission for Weyl semimetals: We present a new theory of photoemission for Weyl semimetals. We derive this\ntheory using a model with a boundary surface at $z=0$. Due to the boundary, the\nself adjoint condition needs to be verified in order to ensure physical\nsolutions. The solutions are given by two chiral zero modes which propagate on\nthe boundary.\n  Due to the Coulomb interaction, the chiral boundary model is in the same\nuniversality class as interacting graphene. The interactions cause a\ntemperature dependence of the velocity and and life time. \\noindent Using the\nprinciple of minimal coupling, we identify the electron-photon Hamiltonian. The\nphotoemission intensity is computed using the $S$-matrix formalism. The\n$S$-matrix is derived using the initial photon state, the final state of a\nphotoelectron and a hole in the valence band. The photoemission reveals the\nfinal valence band dispersion $ \\hbar v(\\pm k_{y}-k_{0})+\\hbar\\Omega$ after\nabsorbing a photon of frequency $ \\Omega$ ($k_{0}$ represents the shift in the\nmomentum due to the crystal potential). The momentum in the $z$ direction is\nnot conserved, and is integrated out. As a result, the scattering matrix is a\nfunction of the parallel momentum . We observe two dimensional contours,\nrepresenting the $^{\"}$Fermi arcs $^{\"}$, which for opposite spin polarization\nhave opposite curvature. This theory is in agreement with previous experimental\nobservations.",
        "positive": "Signature of valley polarization in fractional flux periodicity of a\n  graphene ring: We have studied the interplay of valley polarization and the Coulomb\ninteraction on the energy spectrum, persistent current, and optical absorption\nof a graphene quantum ring. We show that the interaction has a dramatic effect\non the nature of the ground state as a function of the magnetic flux, and that\nthe absence of the exchange interaction in opposite valleys means that the\nsinglet-triplet degeneracy is not lifted for certain states. The additional\nlevel crossings (fractional flux periodicity) due to the interaction directly\nleads to extra steps in the persistent current and intricate structures in the\nabsorption spectrum that should be experimentally observable. By varying the\nwidth of the ring, the nature of the ground state at zero field can be varied\nas well and this is manifest in the measurable properties we discuss."
    },
    {
        "anchor": "Domain wall motion by localized temperature gradients: Magnetic domain wall (DW) motion induced by a localized Gaussian temperature\nprofile is studied in a Permalloy nanostrip within the framework of the\nstochastic Landau-Lifshitz-Bloch equation. The different contributions to\nthermally induced DW motion, entropic torque and magnonic spin transfer torque,\nare isolated and compared. The analysis of magnonic spin transfer torque\nincludes a description of thermally excited magnons in the sample. A third\ndriving force due to a thermally induced dipolar field is found and described.\nFinally, thermally induced DW motion is studied under realistic conditions by\ntaking into account the edge roughness. The results give quantitative insights\ninto the different mechanisms responsible for domain wall motion in temperature\ngradients and allow for comparison with experimental results.",
        "positive": "Fundamental Gates for a Strongly Correlated Two-Electron Quantum Ring: We demonstrate that conditional as well as unconditional basic operations\nwhich are prerequisite for universal quantum gates can be performed with almost\n100% fidelity within a strongly interacting two-electron quantum ring. Both\nsets of operations are based on a quantum control algorithm that optimizes a\ndriving electromagnetic pulse for a given quantum gate. The demonstrated\ntransitions occur on a time scale much shorter than typical decoherence times\nof the system."
    },
    {
        "anchor": "Trigonal distortion of topologically confined channels in bilayer\n  Graphene: In this work we show that the trigonal warping of the electronic bands in\nbilayer graphene dramatically modifies the behavior of the one-dimensional\nmodes topologically confined due to an inhomogeneous bias that changes sign\nacross a channel. The topologically protected states are present but their\nbehavior is disrupted from the predicted in the isotropic approximation. We\npresent detailed studies of the electronic properties of the 1D channel in\nfunction of the orientation of the channel.",
        "positive": "Quantum pumping in graphene nanoribbons at resonant transmission: Adiabatic quantum charge pumping in graphene nanoribbon double barrier\nstructures with armchair and zigzag edges in the resonant transmission regime\nis analyzed. Using recursive Green's function method we numerically calculate\nthe pumped charge for pumping contours encircling a resonance. We find that for\narmchair ribbons the whole resonance line contributes to the pumping of a\nsingle electron (ignoring double spin degeneracy) per cycle through the device.\nThe case of zigzag ribbons is more interesting due to zero-conductance\nresonances. These resonances separate the whole resonance line into several\nparts, each of which corresponds to the pumping of a single electron through\nthe device. Moreover, in contrast to armchair ribbons, one electron can be\npumped from the left lead to the right one or backwards. The current direction\ndepends on the particular part of the resonance line encircled by the pumping\ncontour."
    },
    {
        "anchor": "Anomalous Transport and Possible Phase Transition in Palladium\n  Nanojunctions: Many phenomena in condensed matter are thought to result from competition\nbetween different ordered phases. Palladium is a paramagnetic metal close to\nboth ferromagnetism and superconductivity, and is therefore a potentially\ninteresting material to consider. Nanoscale structuring of matter can modify\nrelevant physical energy scales leading to effects such as locally modified\nmagnetic interactions. We present transport measurements in electromigrated\npalladium break junction devices showing the emergence at low temperatures of\nanomalous sharp features in the differential conductance. These features appear\nsymmetrically in applied bias and exhibit a temperature dependence of their\ncharacteristic voltages reminiscent of a mean field phase transition. The\nsystematic variation of these voltages with zero-bias conductance, together\nwith density functional theory calculations illustrating the relationship\nbetween the magnetization of Pd and atomic coordination, suggest that the\nfeatures may result from the onset of spontaneous magnetization in the\nnanojunction electrodes. We propose that the characteristic conductance\nfeatures are related to inelastic tunneling involving magnetic excitations.",
        "positive": "Majorana fermions in finite-size strips with in-plane magnetic fields: We study the Majorana bound states arising in quasi-one-dimensional systems\nwith Rashba spin-orbit coupling in the presence of an in-plane Zeeman magnetic\nfield. Using two different methods, first, the numerical diagonalization of the\ntight-binding Hamiltonian, and second, finding the singular points of the\nHamiltonian (see Refs. [1-4]), we obtain the topological phase diagram for\nthese systems as a function of the chemical potential and the magnetic field,\nand we demonstrate the consistency of these two methods. By introducing\ndisorder into these systems we confirm that the states with even number of\nMajorana pairs are not topologically protected. Finally, we show that a formal\ncalculation of the $\\mathbb{Z}_2$ topological invariants recovers correctly the\nparity of the number of Majorana bound states pairs, and it is thus fully\nconsistent with the phase diagrams of the disordered systems."
    },
    {
        "anchor": "Determination of substrate pinning in epitaxial and supported graphene\n  layers via Raman scattering: The temperature-induced shift of the Raman G line in epitaxial graphene on\nSiC and Ni surfaces, as well as in graphene supported on SiO2, is investigated\nwith Raman spectroscopy. The thermal shift rate of epitaxial graphene on\n6H-SiC(0001) is found to be about three times that of freestanding graphene.\nThis result is explained quantitatively as a consequence of pinning by the\nsubstrate. In contrast, graphene grown on polycrystalline Ni films is shown to\nbe unpinned, i.e., to behave elastically as freestanding, despite the\nrelatively strong interaction with the metal substrate. Moreover, it is shown\nthat the transfer of exfoliated graphene layers onto a supporting substrate can\nresult in pinned or unpinned layers, depending on the transfer protocol.",
        "positive": "Birth and Early Growth of Entanglement by sd Exchange with\n  Gate-Voltage-Controllable Destiny: We investigate bipartite entanglement between two distant parties, \\textit{A}\nand \\textit{B}, comprising local magnetic impurities (or qudits) induced by the\nquench through \\textit{sd} exchange in a field-effect-transistor geometry. A\nwave-function-based time-dependent formalism is employed by including\nnon-dissipative responses that allow for the control of entanglement via gate\nvoltages. Our study focuses on the birth and early growth of entanglement, by\nintroducing environment support states that render site- and layer-resolved\nlogarithmic negativity (LN) and mutual information (MI). In the minimal set,\nwhere party \\textit{A} (\\textit{B}) consists of a qubit, we identify\nentanglement sudden deaths (ESDs), which are explained by a visualization\npicture analyzing the density matrix. Vibrating electron currents facilitate\nthe birth of entanglement, while they are not required for its growth and\nsubsistence. The LN emerges near the edge layers in \\textit{A} and \\textit{B},\nwhile MI shows up outside these two parties within the spacing layer. The MI is\nborn earlier than the LN. When a gate voltage large enough to disjoint part of\nthe system is applied within the spacing region, it partially suppresses the\nentanglement, quantified by the LN. This suppression does not appear\nimmediately after the presence of the disjoint voltage. Applying this disjoint\nvoltage to the site(s) hosting the qudit(s) helps prevent the site- and\nlayer-resolved LN from encountering ESDs. The local impurities in parties\n\\textit{A} and \\textit{B} are initially of opposite spin directions in an\nunentangled state, as can be prepared by two of our proposed protocols.\nHowever, the features described above do not depend on the chosen protocols."
    },
    {
        "anchor": "Hyperpolarisation of external nuclear spins using nitrogen-vacancy\n  centre ensembles: The nitrogen-vacancy (NV) centre in diamond has emerged as a candidate to\nnon-invasively hyperpolarise nuclear spins in molecular systems to improve the\nsensitivity of nuclear magnetic resonance (NMR) experiments. Several promising\nproof of principle experiments have demonstrated small-scale polarisation\ntransfer from single NVs to hydrogen spins outside the diamond. However, the\nscaling up of these results to the use of a dense NV ensemble, which is a\nnecessary prerequisite for achieving realistic NMR sensitivity enhancement, has\nnot yet been demonstrated. In this work, we present evidence for a polarising\ninteraction between a shallow NV ensemble and external nuclear targets over a\nmicrometre scale, and characterise the challenges in achieving useful\npolarisation enhancement. In the most favourable example of the interaction\nwith hydrogen in a solid state target, a maximum polarisation transfer rate of\n$\\approx 7500$ spins per second per NV is measured, averaged over an area\ncontaining order $10^6$ NVs. Reduced levels of polarisation efficiency are\nfound for liquid state targets, where molecular diffusion limits the transfer.\nThrough analysis via a theoretical model, we find that our results suggest\nimplementation of this technique for NMR sensitivity enhancement is feasible\nfollowing realistic diamond material improvements.",
        "positive": "Conductance oscillations and zero-bias anomaly in a single\n  superconducting junction to a three-dimensional $Bi_2Te_3$ topological\n  insulator: We experimentally investigate Andreev transport through a single junction\nbetween an s-wave indium superconductor and a thick film of a three-dimensional\n$Bi_2Te_3$ topological insulator. We study $Bi_2Te_3$ samples with different\nbulk and surface characteristics, where the presence of a topological surface\nstate is confirmed by direct ARPES measurements. All the junctions demonstrate\nAndreev transport within the superconducting gap. For junctions with\ntransparent $In-Bi_2Te_3$ interfaces we find a number of nearly periodic\nconductance oscillations, which are accompanied by zero-bias conductance\nanomaly. Both effects disappear above the superconducting transition or for\nresistive junctions. We propose a consistent interpretation of both effects as\noriginating from proximity-induced superconducting correlations within the\n$Bi_2Te_3$ topological surface state."
    },
    {
        "anchor": "'Metal'-like transport in high-resistance, high aspect ratio\n  two-dimensional electron gases: We investigate the striking absence of strong localisation observed in\nmesoscopic two-dimensional electron gases (2DEGs) (Baenninger et al 2008 Phys.\nRev. Lett. 100 1016805, Backes et al 2015 Phys. Rev. B 92 235427) even when\ntheir resistivity $\\rho >> h/e^2$. In particular, we try to understand whether\nthis phenomenon originates in quantum many-body effects, or simply percolative\ntransport through a network of electron puddles. To test the latter scenario,\nwe measure the low temperature (low-$T$) transport properties of long and\nnarrow 2DEG devices in which percolation effects should be heavily suppressed\nin favour of Coulomb blockade. Strikingly we find no indication of Coulomb\nblockade and that the high-$\\rho$, low-$T$ transport is exactly similar to that\npreviously reported in mesoscopic 2DEGs with different geometries. Remarkably,\nwe are able to induce a `metal'-insulator transition (MIT) by applying a\nperpendicular magnetic field $B$. We present a picture within which these\nobservations fit into the more conventional framework of the 2D MIT.",
        "positive": "Inertial spin waves in spin spirals: Inertial effects in spin dynamics emerge on picosecond time scales, giving\nrise to nutational excitations at THz frequencies. Here, we describe a general\nframework for investigating the precessional and nutational excitations in any\ntype of spin structure within linear spin-wave theory. We consider the\nparticular cases of planar and conical spin spirals in detail. We observe a\nchange in the sign of the curvature of the high-frequency nutational spin-wave\nband as the spiral period is decreased when passing from the ferromagnetic to\nthe antiferromagnetic limit. We identify conditions for the interaction\nparameters where the curvature changes sign and asymptotical flat bands are\nformed."
    },
    {
        "anchor": "Localization Transition in a Ballistic Quantum Wire: The many-body wave-function of an interacting one-dimensional electron system\nis probed, focusing on the low-density, strong interaction regime. The\nproperties of the wave-function are determined using tunneling between two\nlong, clean, parallel quantum wires in a GaAs/AlGaAs heterostructure, allowing\nfor gate-controlled electron density. As electron density is lowered to a\ncritical value the many-body state abruptly changes from an extended state with\na well-defined momentum to a localized state with a wide range of momentum\ncomponents. The signature of the localized states appears as discrete tunneling\nfeatures at resonant gate-voltages, corresponding to the depletion of single\nelectrons and showing Coulomb-blockade behavior. Typically 5-10 such features\nappear, where the one-electron state has a single-lobed momentum distribution,\nand the few-electron states have double-lobed distributions with peaks at $\\pm\nk_F$. A theoretical model suggests that for a small number of particles (N<6),\nthe observed state is a mixture of ground and thermally excited spin states.",
        "positive": "Ramsey Interferometry of Particle-Hole Pairs in Tunnel Junctions: We present a method to probe real-time dynamics in quantum mesoscopic systems\nusing Ramsey interferometry. This allows us to explore the effect of\ninteractions on quasi-particles in the time domain. We investigate the\ndephasing effects of an ohmic environment on an electron-hole pair in a tunnel\njunction. We show that dynamical Coulomb blockade phenomena can be observed for\nresistances much smaller than the quantum of resistance. Moreover, the\ncrossover between high and low impedance limits can be probed for a constant\nresistance by a proper control of the voltage modulation."
    },
    {
        "anchor": "Majorana fermions in an out-of-equilibrium topological superconducting\n  wire: an exact microscopic transport analysis of a p-wave open chain coupled\n  to normal leads: Topological superconductors are prime candidates for the implementation of\ntopological-quantum-computation ideas because they can support non-Abelian\nexcitations like Majorana fermions. We go beyond the low-energy effective-model\ndescriptions of Majorana bound states (MBSs), to derive non-equilibrium\ntransport properties of wire geometries of these systems in the presence of\narbitrarily large applied voltages. Our approach involves quantum Langevin\nequations and non-equilibrium Green's functions. By virtue of a full\nmicroscopic calculation we are able to model the tunnel coupling between the\nsuperconducting wire and the metallic leads realistically; study the role of\nhigh-energy non-topological excitations; predict how the behavior compares for\nincreasing number of odd vs. even number of sites; and study the evolution\nacross the topological quantum phase transition (QPT). We find that the\nnormalized spectral weight in the MBSs can be remarkably large and goes to zero\ncontinuously at the topological QPT. Our results have concrete implications for\nthe experimental search and study of MBSs.",
        "positive": "Confirmation in graphene of wave packet multilooped dynamics related to\n  fractional quantum Hall state: Cyclotron braid subgroups are defined in order to identify the topological\norigin of Laughlin correlations in 2D Hall systems. Flux-tubes and vortices for\ncomposite fermion constructions are explained in terms of unavoidably\nmultilooped cyclotron braids. A link of braid picture with quasiclassical\nquantum dynamics is conjectured in order to support the phenomenological model\nof composite fermions with auxiliary fluxtubes, for Landau level fillings out\nof 1/p, p odd. The even denominator fractional lowest Landau level fillings,\nincluding Hall metal at n = 1/2, are also discussed in cyclotron braid terms.\nThe topological arguments are utilized to explain novel experimentally observed\nfeatures of the fractional quantum Hall state in graphene including the\ntriggering role of carriers mobility for this collective state."
    },
    {
        "anchor": "Asymmetric Electronic Transport in Porphine: Role of Atomically Precise\n  Tip-Electrode: Electronic conductance through a single molecule is sensitive towards its\nstructural orientation between two electrodes, owing to the distribution of\nmolecular orbitals and their coupling to the electrode levels, that are\ngoverned by quantum confinement effects. Here, we vary the contact geometry of\nthe porphine molecule by attaching two Au tip electrodes that resemble the\nmechanical break junction, via thiol anchoring groups. We investigate the\ncurrent-voltage characteristics of all the contact geometries using\nnon-equilibrium Green's function formalism along with density functional theory\nand tight-binding framework. We observe varying current responses with changing\ncontact sites, originating from varied wave-function delocalization and quantum\ninterference effect. Our calculations show asymmetric current-voltage\ncharacteristics under forward and reverse biases due to structural asymmetry of\nthe tip electrodes in either sides of the molecule. We establish this\nphenomenon as a universal feature for any molecular electronic device,\nirrespective of the inherent structural symmetry of a molecule. This will\nprovide fundamental insights of electronic transport through single molecule in\nreal experimental setup. Furthermore, our observations of varying current\nresponse can further motivate the fabrication of sensor devices with porphine\nbased biomolecules that control important physiological activities, in view of\ntheir applications in advanced diagnostics.",
        "positive": "Dynamics and morphology of chiral magnetic bubbles in perpendicularly\n  magnetized ultra-thin films: We study bubble domain wall dynamics using micromagnetic simulations in\nperpendicularly magnetized ultra-thin films with disorder and\nDzyaloshinskii-Moriya interaction. Disorder is incorporated into the material\nas grains with randomly distributed sizes and varying exchange constant at the\nedges. As expected, magnetic bubbles expand asymmetrically along the axis of\nthe in-plane field under the simultaneous application of out-of-plane and\nin-plane fields. Remarkably, the shape of the bubble has a ripple-like part\nwhich causes a kink-like (steep decrease) feature in the velocity versus\nin-plane field curve. We show that these ripples originate due to the\nnucleation and interaction of vertical Bloch lines. Furthermore, we show that\nthe Dzyaloshinskii-Moriya interaction field is not constant but rather depends\non the in-plane field. We also extend the collective coordinate model for\ndomain wall motion to a magnetic bubble and compare it with the results of\nmicromagnetic simulations."
    },
    {
        "anchor": "Inelastic-impurity-scattering-induced spin texture and topological\n  transitions in surface electron waves: Inelastic scattering off magnetic impurities in a spin-chiral two-dimensional\nelectron gas, e.g., the Rashba system, is shown to generate topological changes\nin the spin texture of the electron waves emanating from the scattering center.\nWhile elastic scattering gives rise to a purely in-plane spin texture for an\nin-plane magnetic scat- tering potential, out-of-plane components emerge upon\nactivation of inelastic scattering processes. This property leads to a\npossibility to make controlled transitions between trivial and nontrivial\ntopologies of the spin texture.",
        "positive": "Electron transport through Al-ZnO-Al: an {\\it ab initio} calculation: The electron transport properties of ZnO nano-wires coupled by two aluminium\nelectrodes were studied by {\\it ab initio} method based on non-equilibrium\nGreen's function approach and density functional theory. A clearly rectifying\ncurrent-voltage characteristics was observed. It was found that the contact\ninterfaces between Al-O and Al-Zn play important roles in the charge transport\nat low bias voltage and give very asymmetric I-V characteristics. When the bias\nvoltage increases, the negative differential resistance occurs at negative bias\nvoltage. The charge accumulation was calculated and its behavior was found to\nbe well correlated with the I-V characteristics. We have also calculated the\nelectrochemical capacitance which exhibits three plateaus at different bias\nvoltages which may have potential device application."
    },
    {
        "anchor": "Efficient single-photon emission from electrically driven InP quantum\n  dots epitaxially grown on Si(001): The heteroepitaxy of III-V semiconductors on silicon is a promising approach\nfor making silicon a photonic platform for on-chip optical interconnects and\nquantum optical applications. Monolithic integration of both material systems\nis a long-time challenge, since different material properties lead to high\ndefect densities in the epitaxial layers. In recent years, nanostructures\nhowever have shown to be suitable for successfully realising light emitters on\nsilicon, taking advantage of their geometry. Facet edges and sidewalls can\nminimise or eliminate the formation of dislocations, and due to the reduced\ncontact area, nanostructures are little affected by dislocation networks. Here\nwe demonstrate the potential of indium phosphide quantum dots as efficient\nlight emitters on CMOS-compatible silicon substrates, with luminescence\ncharacteristics comparable to mature devices realised on III-V substrates. For\nthe first time, electrically driven single-photon emission on silicon is\npresented, meeting the wavelength range of silicon avalanche photo diodes'\nhighest detection efficiency.",
        "positive": "Scattering theory and ground-state energy of Dirac fermions in graphene\n  with two Coulomb impurities: We study the physics of Dirac fermions in a gapped graphene monolayer\ncontaining two Coulomb impurities. For the case of equal impurity charges, we\ndiscuss the ground-state energy using the linear combination of atomic orbitals\n(LCAO) approach. For opposite charges of the Coulomb centers, an electric\ndipole potential results at large distances. We provide a nonperturbative\nanalysis of the corresponding low-energy scattering problem."
    },
    {
        "anchor": "Assessing the role of interatomic position matrix elements in\n  tight-binding calculations of optical properties: We study the role of hopping matrix elements of the position operator\n$\\mathbf{\\hat{r}}$ in tight-binding calculations of linear and nonlinear\noptical properties of solids. Our analysis relies on a Wannier-interpolation\nscheme based on \\textit{ab initio} calculations, which automatically includes\nmatrix elements of $\\mathbf{\\hat{r}}$ between different Wannier orbitals. A\ncommon approximation, both in empirical tight-binding and in\nWannier-interpolation calculations, is to discard those matrix elements, in\nwhich case the optical response only depends on the on-site energies,\nHamiltonian hoppings, and orbital centers. We find that interatomic\n$\\mathbf{\\hat{r}}$-hopping terms make a sizeable contribution to the shift\nphotocurrent in monolayer BC$_2$N, a covalent acentric crystal. If a minimal\nbasis of $p_z$ orbitals on the carbon atoms is used to model the band-edge\nresponse, even the dielectric function becomes strongly dependent on those\nterms.",
        "positive": "Strain-dependent Splitting of Double Resonance Raman Scattering Band in\n  Graphene: Under homogeneous uniaxial strains, the Raman 2D band of graphene involving\ntwo-phonon double-resonance scattering processes splits into two peaks and they\naltogether redshift strongly depending on the direction and magnitude of the\nstrain. Through polarized micro- Raman measurements and first-principles\ncalculations, the effects are shown to originate from significant changes in\nresonant conditions owing to both the distorted Dirac cones and anisotropic\nmodifications of phonon dispersion under uniaxial strains. Quantitative\nagreements between the calculation and experiment enable us to determine the\ndominant double- resonance Raman scattering path, thereby answering a\nfundamental question concerning this key experimental analyzing tool for\ngraphitic systems."
    },
    {
        "anchor": "Negative Poisson's ratio in graphene-based carbon foams: Using molecular dynamics simulations, we find an in-plane negative Poisson's\nratio intrinsically existing in the graphene-based three-dimensional (3D)\ncarbon foams (CFs) when they are compressed uniaxially. Our study shows that\nthe negative Poisson's ratio in the present CFs is attributed to their unique\nmolecular structures and triggered by the buckling of the CF structures. This\nnovel mechanism makes the negative Poisson's ratio of CFs strongly depend on\ntheir cell length, which offers us an efficient means to tune the negative\nPoisson's ratio in nanomaterials. Moreover, as the buckling modes of CFs are\ntopographically different when they are compressed in different directions,\ntheir negative Poisson's ratio is found to be strongly anisotropic, which is in\ncontrast to the isotropic positive Poisson's ratio observed in CFs prior to the\nbuckling. The discovery of the intrinsic negative Poisson's ratio in 3D CFs\nwill significantly expand the family of auxetic nanomaterials. Meanwhile, the\nnovel mechanism of nano-auxetics proposed here may open a door to manufacture\nnew auxetic materials at the nanoscale.",
        "positive": "Multiplets in Emission of Large Quantum Dots in Microcavities: We show theoretically that the emission spectrum of a single large quantum\ndot strongly coupled to a single photon mode in a microcavity can be\nqualitatively different from the spectrum obtained with an atom in a cavity.\nInstead of the well-known Mollow triplet we predict appearance of multiplets\nwith the number of peaks a function of the quantum dot size and pumping\nintensity. The mutiplets can appear if the quantum dot is larger than the\nexciton Bohr radius, so that excitons are confined as whole particles in the\ndot. In this case the Pauli principle is relaxed and one can accommodate more\nthan one exciton (but still a finite number) in a given quantum state."
    },
    {
        "anchor": "Magnetism and Spin Transport of Carbon Chain between Armchair Graphene\n  Nanoribbon electrodes: The magnetic and spin transport properties of a carbon chain between two\narmchair graphene nanoribbon (AGNR) electrodes were studied using tight-binding\nHamiltonian, mean-field Hubbard model and Landauer-Butikker formalism. The\nresults showed that only odd-numbered carbon chains show intrinsic magnetic\nmoments in chain-graphene junctions. It was also found that the electronic,\nmagnetic and spin transport properties of carbon chain-graphene junctions\nstrongly depend on the position and the length of the carbon chains between\nAGNR electrodes. Interestingly, we found a fully spin-polarized transmission\nnear the Fermi energy in all odd-numbered carbon chain-graphene junctions,\nregardless of their lengths and without any magnetic field and magnetic\nelectrodes.",
        "positive": "Non-linear second-order topological insulators: We demonstrate, both theoretically and experimentally, the concept of\nnon-linear second-order topological insulators, a class of bulk insulators with\nquantized Wannier centers and a bulk polarization directly controlled by the\nlevel of non-linearity. We show that one-dimensional edge states and\nzero-dimensional corner states can be induced in a trivial crystal insulator\nmade of evanescently coupled resonators with linear and nonlinear coupling\ncoefficients, simply by tuning the excitation intensity. This allows global\nexternal control over topological phase transitions and switching to a phase\nwith non-zero bulk polarization, without requiring any structural or\ngeometrical changes. We further show how these non-linear effects enable\ndynamic tuning of the spectral properties and localization of the topological\nedge and corner states. Such self-induced second-order topological insulators,\nwhich can be found and implemented in a wide variety of physical platforms\nranging from electronics to microwaves, acoustics, and optics, hold exciting\npromises for reconfigurable topological energy confinement, power harvesting,\ndata storage, and spatial management of high-intensity fields."
    },
    {
        "anchor": "Asymmetric velocity and tilt angle of domain walls induced by spin-orbit\n  torques: We present a micromagnetic study of the current-induced domain wall motion in\nperpendicularly magnetized Pt/Co/AlOx racetracks. We show that the domain wall\nvelocity depends critically on the tilt angle of the wall relative to the\ncurrent direction, which is determined by the combined action of the\nDzyaloshinskii-Moriya interaction, damping-like, and field-like spin-orbit\ntorques. The asymmetry of the domain wall velocity can be controlled by\napplying a bias-field perpendicular to the current direction as well as by the\ncurrent amplitude. As the faster domain walls are expelled rapidly from the\nracetrack boundaries, we argue that the domain wall velocity and tilt measured\nexperimentally depend on the timescale of the observations. Our findings\nreconcile the discrepancy between time-resolved and quasi-static domain wall\nmeasurements in which domain walls with opposite tilts were observed and are\nrelevant to tune the velocity of domain walls in racetrack structures.",
        "positive": "Imaging Generalized Wigner Crystal States in a WSe2/WS2 Moir\u00e9\n  Superlattice: The Wigner crystal state, first predicted by Eugene Wigner in 1934, has\nfascinated condensed matter physicists for nearly 90 years2-14. Studies of\ntwo-dimensional (2D) electron gases first revealed signatures of the Wigner\ncrystal in electrical transport measurements at high magnetic fields2-4. More\nrecently optical spectroscopy has provided evidence of generalized Wigner\ncrystal states in transition metal dichalcogenide (TMDC) moir\\'e superlattices.\nDirect observation of the 2D Wigner crystal lattice in real space, however, has\nremained an outstanding challenge. Scanning tunneling microscopy (STM) in\nprinciple has sufficient spatial resolution to image a Wigner crystal, but\nconventional STM measurements can potentially alter fragile Wigner crystal\nstates in the process of measurement. Here we demonstrate real-space imaging of\n2D Wigner crystals in WSe2/WS2 moir\\'e heterostructures using a novel\nnon-invasive STM spectroscopy technique. We employ a graphene sensing layer in\nclose proximity to the WSe2/WS2 moir\\'e superlattice for Wigner crystal\nimaging, where local STM tunneling current into the graphene sensing layer is\nmodulated by the underlying electron lattice of the Wigner crystal in the\nWSe2/WS2 heterostructure. Our measurement directly visualizes different lattice\nconfigurations associated with Wigner crystal states at fractional electron\nfillings of n = 1/3, 1/2, and 2/3, where n is the electron number per site. The\nn=1/3 and n=2/3 Wigner crystals are observed to exhibit a triangle and a\nhoneycomb lattice, respectively, in order to minimize nearest-neighbor\noccupations. The n = 1/2 state, on the other hand, spontaneously breaks the\noriginal C3 symmetry and forms a stripe structure in real space. Our study lays\na solid foundation toward the fundamental understanding of rich Wigner crystal\nstates in WSe2/WS2 moir\\'e heterostructures."
    },
    {
        "anchor": "Transport and noise properties of a normal metal-superconductor-normal\n  metal junction with mixed singlet and chiral triplet pairings: We study transport and zero frequency shot noise properties of a normal\nmetal-superconductor-normal metal (NSN) junction, with the superconductor\nhaving mixed singlet and chiral triplet pairings. We show that in the subgapped\nregime when the chiral triplet pairing amplitude dominates over that of the\nsinglet, a resonance phenomena emerges out at zero energy where all the quantum\nmechanical scattering probabilities acquire a value of 0.25. At the resonance,\ncrossed Andreev reflection mediating through such junction, acquires a zero\nenergy peak. This reflects as a zero energy peak in the conductance as well\ndepending on the doping concentration. We also investigate shot noise for this\nsystem and show that shot noise cross-correlation is negative in the subgapped\nregime when the triplet pairing dominates over the singlet one. The latter is\nin sharp contrast to the positive shot noise obtained when the singlet pairing\nis the dominating one.",
        "positive": "Dynamic spin-charge coupling: spin Hall magnetoresistance in\n  non-magnetic conductors: The dynamic coupling between spin and charge currents in non-magnetic\nconductors is considered. As a consequence of this coupling, the spin dynamics\nis directly reflected in the electrical impedance of the sample, with a\nrelevant frequency scale defined by spin relaxation and spin diffusion. This\nallows the observation of the electron spin resonance by purely electrical\nmeasurements."
    },
    {
        "anchor": "How to interpret the spectral density of the Keldysh nonequilibrium\n  Green's function: This paper is devoted to the study and interpretation of the spectral\nfunction $\\mathbf{A}(\\omega, T)$ of the Keldysh nonequilibrium Green's\nfunction. The spatial diagonal of the spectral function is often interpreted as\na time-dependent local density of states. We show that this object can take\nnegative values implying that a simple probability interpretation as a\ntime-dependent density of states is not possible. The same issue also occurs\nfor the Wigner function $P(x,p)$ where it is solved by taking the uncertainty\nprinciple into account. We follow the same path and incorporate the time-energy\nuncertainty relation to define a convoluted spectral function that allows for a\nprobability interpretation. The usefulness of this quantity as a interpretative\ntool is demonstrated by visualizing the charge dynamics in a quantum dot\ncoupled to superconducting leads.",
        "positive": "Time-resolved statistics of photon pairs in two-cavity Josephson\n  photonics: We analyze the creation and emission of pairs of highly nonclassical\nmicrowave photons in a setup where a voltage-biased Josephson junction is\nconnected in series to two electromagnetic oscillators. Tuning the external\nvoltage such that the Josephson frequency equals the sum of the two mode\nfrequencies, each tunneling Cooper pair creates one additional photon in both\nof the two oscillators. The time-resolved statistics of photon emission events\nfrom the two oscillators is investigated by means of single- and\ncross-oscillator variants of the second-order correlation function\n$g^{(2)}(\\tau)$ and the waiting-time distribution $w(\\tau)$. They provide\ninsight into the strongly correlated quantum dynamics of the two oscillator\nsubsystems and reveal a rich variety of quantum features of light including\nstrong antibunching and the presence of negative values in the Wigner function."
    },
    {
        "anchor": "Full consideration of acoustic phonon scatterings in two-dimensional\n  Dirac materials: The in-plane acoustic phonon scattering in graphene is solved by considering\nfully inelastic acoustic phonon scatterings in two-dimensional (2D) Dirac\nmaterials for large range of temperature ($T$) and chemical potential ($\\mu$).\nRigorous analytical solutions and symmetry properties of Fermionic and Bosonic\nfunctions are obtained. We illustrate how doping alters the temperature\ndependence of acoustic phonon scattering rates. It is shown that the\nquasi-elastic and ansatz equations previously derived for acoustic phonon\nscatterings in graphene are limiting cases of the inelastic-scattering\nequations derived here. For heavily-doped graphene, we found that the high-$T$\nbehavior of resistivity is better described by $\\rho(T, \\mu) \\propto T(1 -\n\\zeta_a\\mu^2/3(k_BT)^2)$ rather than a linear $T$ behavior, and in the low $T$\nregime we found $\\tau^{-1} \\propto (k_BT)^4$ but with a different prefactor\n(i.e. $\\sim$ 3 times smaller) in comparison with the existing quasi-elastic\nexpressions. Furthermore, we found a simple analytic \"semi-inelastic\"\nexpression of the form $\\tau^{-1} \\propto (k_BT)^4/(1+ c T^3)$ which matches\nnearly perfectly with the full inelastic results for any temperature up to 500\nK and $\\mu$ up to 1 eV. Our simple analytic results agree well with previous\nfirst-principles studies and available experimental data. Moreover, we obtain\nan analytical form for the acoustic gauge field $\\beta_A =\n3\\beta\\gamma_0/4\\sqrt{2}$. Our analyses pave a way for investigating\nscatterings between electrons and other fundamental excitations with linear\ndispersion relation in 2D Dirac material-based heterostructures such as\nbogolon-mediated electron scattering in graphene-based hybrid Bose-Fermi\nsystems.",
        "positive": "Hole mediated ferromagnetism in Cu-doped ZnO thin films: We report the successful synthesis of ZnO:Cu thin films doped with holes,\nresulting in room temperature ferromagnetism. Hole doping is achieved by\nAs-diffusion from the GaAs substrate into ZnO films, assisted by thermal\nannealing. The As-diffusion is probed with the help of x-ray absorption spectra\ncollected at the As K-edge which show enhanced signature of diffusion in the\nannealed samples. Introduction of holes, due to the As doping, in ZnO films is\nfurther evidenced by the Cu L3,2-edge spectra. XMCD and magnetic measurements\nshow that the ferromagnetic interaction between doped Cu ions is enhanced after\nhole doping."
    },
    {
        "anchor": "Time-domain response of atomically thin $\\mathrm{MoS_2}$ nanomechanical\n  resonators: We measure the energy relaxation rate of single- and few-layer molybdenum\ndisulphide ($\\mathrm{MoS_2}$) nanomechanical resonators by detecting the\nresonator ring-down. Recent experiments on these devices show a remarkably low\nquality (Q)-factor when taking spectrum measurements at room temperature. The\norigin of the low spectral Q-factor is an open question, and it has been\nproposed that besides dissipative processes, frequency fluctuations contribute\nsignificantly to the resonance line-width. The spectral measurements performed\nthus far however, do not allow one to distinguish these two processes. Here, we\nuse time-domain measurements to quantify the dissipation. We compare the\nQ-factor obtained from the ring-down measurements to those obtained from the\nthermal noise spectrum and from the frequency response of the driven device. In\nfew-layer and single-layer $\\mathrm{MoS_2}$ resonators the two are in close\nagreement, which demonstrates that the spectral line-width in $\\mathrm{MoS_2}$\nmembranes at room temperature is limited by dissipation, and that excess\nspectral broadening plays a negligible role.",
        "positive": "S-matrix network models for coherent waves in random media: construction\n  and renormalization: Networks of random quantum scatterers (S-matrices) form paradigmatic models\nfor the propagation of coherent waves in random S-matrix network models cover\nuniversal localization-delocalization properties and have some advantages over\nmore traditional Hamiltonian models. In particular, a straightforward\nimplementation of real space renormalization techniques is possible. Starting\nfrom a finite elementary cell of the S-matrix network, hierarchical network\nmodels can be constructed by recursion. The localization-delocalization\nproperties are contained in the flow of the forward scattering strength\n('conductance') under increasing system size. With the aid of 'small scale'\nnumerics qualitative aspects of the localization-delocalization properties of\nS-matrix network models can be worked out."
    },
    {
        "anchor": "Spintronic devices on the base of magnetic nanostructures: Two types of spintronic devices on the base of magnetic nanostructures\ncontaining silicon dioxide films with cobalt nanoparticles SiO2(Co) on GaAs\nsubstrate - magnetic sensors and field-effect transistor governed by applied\nmagnetic field - are studied. Magnetic sensors are based on the injection\nmagnetoresistance effect. This effect manifests itself in avalanche suppression\nby the magnetic field in GaAs near the SiO2(Co)/GaAs interface. Field-effect\ntransistor contains the SiO2(Co) film under gate. It is found that the magnetic\nfield action leads to great changes in electron mobility in the channel due to\nthe interaction between spins of Co nanoparticles and electron spins.",
        "positive": "Zero Energy Modes and Gate-Tunable Gap in Graphene on hexagonal Boron\n  Nitride: In this Letter, we derive an effective theory of graphene on a hexagonal\nBoron Nitride (h-BN) substrate. We show that the h-BN substrate generically\nopens a spectral gap in graphene despite the lattice mismatch. The origin of\nthat gap is particularly intuitive in the regime of strong coupling between\ngraphene and its substrate, when the low-energy physics is determined by the\ntopology of a network of zero energy modes. For twisted graphene bilayers,\nwhere inversion symmetry is present, this network percolates through the system\nand the spectrum is gapless. The breaking of that symmetry by h-BN causes the\nzero energy modes to close into rings. The eigenstates of these rings hybridize\ninto flat bands with gaps in between. The size of this band gap can be tuned by\na gate voltage and it can reach the order of magnitude needed to confine\nelectrons at room temperature."
    },
    {
        "anchor": "Inelastic vibrational signals in electron transport across graphene\n  nanoconstrictions: We present calculations of the inelastic vibrational signals in the\nelectrical current through a graphene nanoconstriction. We find that the\ninelastic signals are only present when the Fermi-level position is tuned to\nelectron transmission resonances, thus, providing a fingerprint which can link\nan electron transmission resonance to originate from the nanoconstriction. The\ncalculations are based on a novel first-principles method which includes the\nphonon broadening due to coupling with phonons in the electrodes. We find that\nthe signals are modified due to the strong coupling to the electrodes, however,\nstill remain as robust fingerprints of the vibrations in the nanoconstriction.\nWe investigate the effect of including the full self-consistent potential drop\ndue to finite bias and gate doping on the calculations and find this to be of\nminor importance.",
        "positive": "Unprotected edge modes in quantum spin Hall insulator candidate\n  materials: The experiments in quantum spin Hall insulator candidate materials, such as\nHgTe/CdTe and InAs/GaSb heterostructures, indicate that in addition to the\ntopologically protected helical edge modes these multilayer heterostructures\nmay also support additional edge states, which can contribute to the scattering\nand the transport. We use first-principles calculations to derive an effective\ntight-binding model for HgTe/CdTe, HgS/CdTe and InAs/GaSb heterostructures, and\nwe show that all these materials support additional edge states which are\nsensitive to the edge termination. We trace the microscopic origin of these\nstates back to a minimal model supporting flat bands with a nontrivial quantum\ngeometry that gives rise to polarization charges at the edges. We show that the\npolarization charges transform into the additional edge states when the flat\nbands are coupled to each other and to the other states to form the Hamiltonian\ndescribing the full heterostructure. Interestingly, in the HgTe/CdTe quantum\nwells the additional edge states are far away from the Fermi level so that they\ndo not contribute to the transport but in the HgS/CdTe and InAs/GaSb\nheterostructures they appear within the bulk energy gap giving rise to the\npossibility of multimode edge transport. Finally, we demonstrate that because\nthese additional edge modes are non-topological it is possible to remove them\nfrom the bulk energy gap by modifying the edge potential for example with the\nhelp of a side gate or chemical doping."
    },
    {
        "anchor": "Local density of states of two-dimensional electron systems under strong\n  in-plane electric and perpendicular magnetic fields: We calculate the local density of states of a two-dimensional electron system\nunder strong crossed magnetic and electric fields. We assume a strong\nperpendicular magnetic field which, in the absence of in-plane electric fields\nand collision broadening effects, leads to Landau quantization and the\nwell-known singular Landau density of states. Unidirectional in-plane electric\nfields lead to a broadening of the delta-function-singularities of the Landau\ndensity of states. This results in position-dependent peaks of finite height\nand width, which can be expressed in terms of the energy eigenfunctions. These\npeaks become wider with increasing strength of the electric field and may\neventually overlap, which indicates the onset of inter-Landau-level scattering,\nif electron-impurity scattering is considered. We present analytical results\nfor two simple models and discuss their possible relevance for the breakdown of\nthe integer quantized Hall effect. In addition, we consider a more realistic\nmodel for an incompressible stripe separating two compressible regions, in\nwhich nearly perfect screening pins adjacent Landau levels to the\nelectrochemical potential. We also discuss the effect of an imposed current on\nthe local density of states in the stripe region.",
        "positive": "Mass-loading induced dephasing in nanomechanical resonators: I study dephasing of an underdamped nanomechanical resonator subject to\nrandom mass loading of small particles. I present a frequency noise model which\ndescribes dephasing due to attachment and detachment of particles at random\npoints and particle diffusion along the resonator. This situation is commonly\nencountered in current mass measurement experiments using NEM resonators. I\ndiscuss the conditions which can lead to inhomogeneous broadening and fine\nstructure in the modes absorption spectra. I also show that the spectra of the\nhigher order cumulants of the (complex) vibrational mode amplitude are\nsensitive to the parameters characterizing the frequency noise process. Hence,\nmeasurement of these cumulants can provide information not only about the mass\nbut also about other parameters of the particles (diffusion coefficient and\nattachment-detachment rates.)"
    },
    {
        "anchor": "Decoherence and relaxation of single electron excitations in quantum\n  Hall edge channels: A unified approach to decoherence and relaxation of energy resolved single\nelectron excitations in Integer Quantum Hall edge channels is presented. Within\nthe bosonization framework, relaxation and decoherence induced by interactions\nand capacitive coupling to an external linear circuit are computed. An explicit\nconnexion with high frequency transport properties of a two terminal device\nformed by the edge channel on one side and the linear circuit on the other side\nis established.",
        "positive": "Spin-half paramagnetism in graphene induced by point defects: Using magnetization measurements, we show that point defects in graphene -\nfluorine adatoms and irradiation defects (vacancies) - carry magnetic moments\nwith spin 1/2. Both types of defects lead to notable paramagnetism but no\nmagnetic ordering could be detected down to liquid helium temperatures. The\ninduced paramagnetism dominates graphene's low-temperature magnetic properties\ndespite the fact that maximum response we could achieve was limited to one\nmoment per approximately 1000 carbon atoms. This limitation is explained by\nclustering of adatoms and, for the case of vacancies, by losing graphene's\nstructural stability."
    },
    {
        "anchor": "Performance of graphene Hall effect sensors: role of bias current,\n  disorder and Fermi velocity: Graphene Hall effect magnetic field sensors hold great promise for the\ndevelopment of ultra-sensitive magnetometers. Their performance is frequently\nanalysed using the two-channel model where electron and hole conductivities are\nsimply added. Unfortunately, this model is unable to capture all the features\nof the sensor, particularly the bias current dependence of the magnetic field\nsensitivity. Here we present an advanced model that provides an in-depth\nunderstanding of how graphene Hall sensors operate, and demonstrate its ability\nto quantitatively assess their performance. First, we report the fabrication of\nsensors with different qualities of graphene, with the best devices achieving\nmagnetic field sensitivities as high as 5000 ohms/T, outperforming the best\nsilicon and narrow-gap semiconductor-based sensors. Then, we examine their\nperformance in detail using the proposed numerical model, which combines\nBoltzmann formalism, with distinct Fermi levels for electrons and holes, and a\nnew method for the introduction of substrate-induced electron-hole puddles.\nImportantly, the dependences of magnetic field sensitivity on bias current,\ndisorder, substrate and Hall bar geometry are quantitatively reproduced for the\nfirst time. In addition, the model emphasizes that the performance of devices\nwith widths of the order of the charge carrier diffusion length, is\nsignificantly affected by the bias current due to the occurrence of large and\nnon-symmetric carrier accumulation and depletion areas near the edges of the\nHall bar. The formation of these areas induces a transverse diffusion particle\nflux capable of counterbalancing the particle flux induced by the Lorentz force\nwhen the Hall electric field cancels out in the ambipolar regime. Finally, we\ndiscuss how sensor performance can be enhanced by Fermi velocity engineering,\npaving the way for future ultra-sensitive graphene Hall effect sensors.",
        "positive": "Self-consistent calculation of electric potentials in Hall devices: Using a first-principles classical many-body simulation of a Hall bar, we\nstudy the necessary conditions for the formation of the Hall potential: (i)\nOhmic contacts with metallic reservoirs, (ii) electron-electron interactions,\nand (iii) confinement to a finite system. By propagating thousands of\ninteracting electrons over million time-steps we capture the build-up of the\nself-consistent potential, which resembles results obtained by\nconformal-mapping methods. As shown by a microscopic model of the current\ninjection, the Hall effect is linked to specific boundary conditions at the\nparticle reservoirs."
    },
    {
        "anchor": "Autoresonant control of the magnetization switching in single-domain\n  nanoparticles: The ability to control the magnetization switching in nanoscale devices is a\ncrucial step for the development of fast and reliable techniques to store and\nprocess information. Here we show that the switching dynamics can be controlled\nefficiently using a microwave field with slowly varying frequency\n(autoresonance). This technique allowed us to reduce the applied field by more\nthan $30%$ compared to competing approaches, with no need to fine-tune the\nfield parameters. For a linear chain of nanoparticles the effect is even more\ndramatic, as the dipolar interactions tend to cancel out the effect of the\ntemperature. Simultaneous switching of all the magnetic moments can thus be\nefficiently triggered on a nanosecond timescale.",
        "positive": "Charge and Spin Dynamics and Enantioselectivity in Chiral Molecules: Charge and spin dynamics is addressed in chiral molecules immediately after\nthe instantaneous coupling to an external metallic reservoir. It is shown how a\nspin-polarization is induced in the chiral structure as a response to the\ncharge dynamics. The dynamics indicate that chiral induced spin selectivity is\nan excited states phenomenon which, in the transient regime partly can be\ncaptured using a simplistic single particle description, however, in the\nstationary limit definitively shows that electron correlations, e.g.,\nelectron-vibration interactions, crucially contribute to sustain an intrinsic\nspin anisotropy that can lead to a non-vanishing spin selectivity. The\ndynamics, moreover, provide insight to enantiomer separation, due to different\nacquired spin-polarizations."
    },
    {
        "anchor": "Confined one-way mode at magnetic domain wall for broadband\n  high-efficiency one-way waveguide, splitter and bender: We find the one-way mode can be well-confined at the magnetic domain wall by\nthe photonic bandgap of gyromagnetic bulk material. Utilizing the well-confined\none-way mode at the domain wall, we demonstrate the photonic one-way waveguide,\nsplitter and bender can be realized with simple structures, which are predicted\nto be high-efficiency, broadband, frequency-independent, reflection-free,\ncrosstalk-proof and robustness against disorder. Additionally, we find that the\nsplitter and bender in our proposal can be transformed into each other with\nmagnetic control, which may have great potential applications in all photonic\nintegrated circuit.",
        "positive": "On the diameter dependence of metal-nanowire Schottky barrier height: Bardeen's model for the non-ideal metal-semiconductor interface was applied\nto metal-wrapped cylindrical nanowire systems; a significant effect of the\nnanowire diameter on the non-ideal Schottky barrier height was found. The\ncalculations were performed by solving Poisson's equation in the nanowire,\nself-consistently with the constraints set by the non-ideal interface\nconditions; in these calculations the barrier height is obtained from the\nsolution, and it is not a boundary condition for Poisson's equation. The main\nfinding is that thin nanowires are expected to have tens of meV higher Schottky\nbarriers compared to their thicker counterparts. What lies behind this effect\nis the electrostatic properties of metal-wrapped nanowires; in particular,\nsince depletion charge is reduced with nanowire radius, the potential drop on\nthe interfacial layer, is reduced - leading to the increase of the barrier\nheight with nanowire radius reduction."
    },
    {
        "anchor": "What do noise measurements reveal about fractional charge in FQH\n  liquids?: We present a calculation of noise in the tunneling current through junctions\nbetween two two-dimensional electron gases (2DEG) in inequivalent Laughlin\nfractional quantum Hall (FQH) states, as a function of voltage and temperature.\nWe discuss the interpretation of measurements of suppressed shot noise levels\nof tunneling currents through a quantum point contact (QPC) in terms of\ntunneling of fractionally charged states. We show that although this\ninterpretation is always possible, for junctions between different FQH states\nthe fractionally charged states involved in the tunneling process are not the\nLaughlin quasiparticles of the isolated FQH states that make up the junction,\nand should be regarded instead as solitons of the coupled system. The charge of\nthe soliton is, in units of the electron charge, the harmonic average of the\nfilling fractions of the individual Laughlin states, which also coincides with\nthe saturation value of the differential conductance of the QPC. For the\nespecially interesting case of a QPC between states at filling fractions\n$\\nu=1$ and $\\nu={{1/3}}$, we calculate the noise in the tunneling current\nexactly for all voltages and temperatures and investigate the crossovers. These\nresults can be tested by noise experiments on $(1,{{1/3}})$ QPCs. We present a\ngeneralization of these results for QPC's of arbitrary Laughlin fractions in\ntheir weak and strong coupling regimes. We also introduce generalized Wilson\nratios for the noise in the shot and thermal limits. These ratios are universal\nscaling functions of $V/T$ that can be measured experimentally in a general QPC\ngeometry.",
        "positive": "Molecular electronics based on self-assembled monolayers: Since the first measurement of electron tunneling through an organic\nmonolayer in 1971,(Mann and Kuhn, 1971) and the gedanken experiment of a\nmolecular current rectifying diode in 1974,(Aviram and Ratner, 1974)\nmolecular-scale electronics have attracted a growing interest, both for basic\nscience at the nanoscale and for possible applications in nano-electronics. In\nthe first case, molecules are quantum object by nature and their properties can\nbe tailored by chemistry opening avenues for new experiments. In the second\ncase, molecule-based devices are envisioned to complement silicon devices by\nproviding new functions or already existing functions at a simpler process\nlevel and at a lower cost by virtue of their self-organization capabilities,\nmoreover, they are not bound to von Neuman architecture and this may open the\nway to other architectural paradigms. After a brief overview of the\nnanofabrication of molecular devices, we review in this chapter, the electronic\nproperties of several basic devices, from simple molecules such as molecular\ntunnel junctions and molecular wires, to more complex ones such as molecular\nrectifying diodes, molecular switches and memories."
    },
    {
        "anchor": "Time reversal, fermion doubling, and the masses of lattice Dirac\n  fermions in three dimensions: Motivated by recent examples of three-dimensional lattice Hamiltonians with\nmassless Dirac fermions in their (bulk) spectrum, I revisit the problem of\nfermion doubling on bipartite lattices. The number of components of the Dirac\nfermion in a time-reversal and parity invariant d-dimensional lattice system is\ndetermined by the minimal representation of the Clifford algebra of $d+1$\nHermitian Dirac matrices that allows a construction of the time-reversal\noperator with the square of unity, and it equals $2^d$ for $d=2,3$. Possible\nmass-terms for (spinless) Dirac fermions are listed and discussed. In three\ndimensions there are altogether eight independent masses, out of which four are\neven, and four are odd under time reversal. A specific violation of\ntime-reversal symmetry that leads to (minimal) four-component massless Dirac\nfermion in three dimensions at low energies is constructed.",
        "positive": "Quasi-Particle density of states of disordered d-wave superconductors: We present a numerical study of the quasi-particle density of states\n  (DoS) of two-dimensional d-wave superconductors in the presence of\n  smooth disorder. We find power law scaling of the DoS with an\n  exponent depending on the strength of the disorder and the\n  superconducting order parameter in quantitative agreement with the\n  theory of Nersesyan et al. (Phys.Rev.Lett. 72,\n  2628 (1994)). For strong disorder a transition to a constant DoS\n  occurs. Our results are in contrast to the case of short-ranged\n  disorder."
    },
    {
        "anchor": "Nonlinear Damping in Graphene Resonators: Based on a continuum mechanical model for single-layer graphene we propose\nand analyze a microscopic mechanism for dissipation in nanoelectromechanical\ngraphene resonators. We find that coupling between flexural modes and in-plane\nphonons leads to linear and nonlinear damping of out-of-plane vibrations. By\ntuning external parameters such as bias and ac voltages, one can cross over\nfrom a linear to a nonlinear-damping dominated regime. We discuss the behavior\nof the effective quality factor in this context.",
        "positive": "Spectroscopic Characterization of Landau Level Splitting and the\n  Intermediate v = 0 Phase in Bilayer Graphene: Despite various novel broken symmetry states have been revealed in bilayer\ngraphene (BLG) experimentally, the atomic-scale spectroscopic investigation has\nbeen greatly limited. Here, we study high-resolution spectroscopic\ncharacteristics of high-quality BLG and observe rich broken-symmetry-induced\nLandau level (LL) splittings, including valley, spin and orbit, by using\nultralow-temperature and high-magnetic-field scanning tunneling microscopy and\nspectroscopy (STM and STS). Our experiment demonstrates that both the spin and\norbital splittings of the lowest n = (0,1) LL depend sensitively on its filling\nand exhibit an obvious enhancement at partial-filling states. More\nunexpectedly, the splitting of a fully-filled and valley-polarized LL is also\nenhanced by partial filling of the LL with the opposite valley. These results\nreveal significant many-body effects in this system. At half filling of the n =\n(0,1) LL (filling factor v = 0), a single-particle intermediate v = 0 phase,\nwhich is the transition state between canted antiferromagnetic and\nlayer-polarized states in the BLG, is measured and directly visualized at the\natomic scale. Our atomic-scale STS measurement gives direct evidence that this\nintermediate v = 0 state is the predicted orbital-polarized phase."
    },
    {
        "anchor": "Molecular Conductance from Ab Initio Calculations: Self Energies and\n  Absorbing Boundary Conditions: Calculating an exact self energy for ab initio transport calculations\nrelevant to ``Molecular Electronics'' can be troublesome. Errors or\ninsufficient approximations made at this step are often the reason why many\nmolecular transport studies become inconclusive. We propose a simple and\nefficient approximation scheme, that follows from interpreting the self energy\nas an absorbing boundary condition of an effective Schroedinger equation. In\norder to explain the basic idea, a broad introduction into the physics\nincorporated in these self energies is given. The method is further illustrated\nusing a tight binding wire as a toy model. Finally, also more realistic\napplications for transport calculations based on the density functional theory\nare included.",
        "positive": "Donor binding energy and thermally activated persistent\n  photoconductivity in high mobility (001) AlAs quantum wells: A doping series of AlAs (001) quantum wells with Si delta-modulation doping\non both sides reveals different dark and post-illumination saturation\ndensities, as well as temperature dependent photoconductivity. The lower dark\ntwo-dimensional electron density saturation is explained assuming deep binding\nenergy of Delta_DK = 65.2 meV for Si-donors in the dark. Persistent\nphotoconductivity (PPC) is observed upon illumination, with higher saturation\ndensity indicating shallow post-illumination donor binding energy. The\nphotoconductivity is thermally activated, with 4 K illumination requiring\npost-illumination annealing to T = 30 K to saturate the PPC. Dark and\npost-illumination doping efficiencies are reported."
    },
    {
        "anchor": "Phase measurements in open and closed Aharonov-Bohm interferometers: Mesoscopic Aharonov-Bohm interferometers have been used in attempts to\nmeasure the transmission phase of a quantum dot which is placed on one arm of\nthe interferometer. Here we review theoretical results for the conductance\nthrough such interferometers, for both the closed (two-terminal) and open\n(multi-terminal) cases. In addition to earlier results for the Coulomb blockade\nregime, we present new results for the strongly correlated Kondo regime, and\ntest the consistency of the two-slit analysis of some data from open\ninterferometer experiments.",
        "positive": "Rashba contribution of 2D Dirac-Weyl fermions: Beyond ordinary quantum\n  regime: We study the energy levels of Dirac-Weyl fermions in graphene subject to a\nmagnetic field with Rashba contribution in the minimal length situation. The\nexact solution for the energy dispersion of Dirac-like charge carriers coupled\nto the magnetic moments in a (2+1)-dimension is obtained by the use of the\nmomentum space representation. Moreover, as it comes to applications for 2D\nDirac-like quasiparticles, we also extend our theory and results in some\nspecial cases, showing that the emerging energy spectrum at the high magnetic\nfield limit becomes independent of the Rashba coupling, $\\lambda_{R}$, and the\nband index of Landau levels."
    },
    {
        "anchor": "Spin-wave propagation and transformation in a thermal gradient: The influence of a thermal gradient on the propagation properties of\nexternally excited dipolar spin waves in a magnetic insulator waveguide is\ninvestigated. It is shown that spin waves propagating towards a colder region\nalong the magnetization direction continuously reduce their wavelength. The\nwavelength increase of a wave propagating into a hotter region was utilized to\nrealize its decomposition in the partial waveguide modes which are reflected at\ndifferent locations. This influence of temperature on spin-wave properties is\nmainly caused by a change in the saturation magnetization and yields promising\nopportunities for the manipulation of spin waves in spin-caloritronic\napplications.",
        "positive": "Quasiparticles of periodically driven quantum dot coupled between\n  superconducting and normal leads: We investigate subgap quasiparticles of a single level quantum dot coupled to\nthe superconducting and normal leads, whose energy level is periodically driven\nby external potential. Using the Floquet formalism we determine the\nquasienergies and analyze redistribution of their spectral weights between\nindividual harmonics upon varying the frequency and amplitude of the driving\npotential. We also propose feasible spectroscopic methods for probing the\nin-gap quasiparticles observable in the differential conductance of the charge\ncurrent averaged over a period of oscillations."
    },
    {
        "anchor": "Evidence for a string-net matter: Further experiments showed the incorrectness of proposed interpretation.",
        "positive": "Interaction between single vacancies in graphene sheet: An ab initio\n  calculation: In order to investigate the interaction between single vacancies in a\ngraphene sheet, we have used spin-polarized density functional theory (DFT).\nTwo distinct configurations were considered, either with the two vacancies\nlocated in the same sublattice or in different sublattices, and the effect of\nchanging the separation between the vacancies was also studied. Our results\nshow that the ground state of the system is indeed magnetic, but the presence\nof the vacancies in the same sublattice or in different sublattices and the\npossible topological configurations can lead to different contributions from\nthe $\\pi$ and $\\sigma$ orbitals to magnetism. On the other hand, our findings\nreveal that the net magnetic moment of the system with the two vacancies in the\nsame sublattice move towards the value of the magnetic moment per isolated\nvacancy with the increase of the distance between the vacancies, which is\nascribed to the different contributions due to $\\pi$ electrons. Moreover, it is\nalso found that the local magnetic moments for vacancies in the same sublattice\nare in parallel configuration, while they have different orientations when the\nvacancies are created in different sublattices. So, our findings have clearly\nevidenced how difficult it would be to observe experimentally the emergence of\nmagnetic order in graphene-based systems containing randomly created atomic\nvacancies, since the energy difference between cases of antiferromagnetic and\nferromagnetic order decreases quickly with the increase in the distance\nseparating each vacancy pair."
    },
    {
        "anchor": "Spin relaxation in mesoscopic superconducting Al wires: We studied the diffusion and the relaxation of the polarized quasiparticle\nspins in superconductors. To that end, quasiparticles of polarized spins were\ninjected through an interface of a mesoscopic superconducting Al wire in\nproximity contact with an overlaid ferromagnetic Co wire in the single-domain\nstate. The superconductivity was observed to be suppressed near the\nspin-injecting interface, as evidenced by the occurrence of a finite voltage\nfor a bias current below the onset of the superconducting transition. The spin\ndiffusion length, estimated from finite voltages over a certain length of Al\nwire near the interface, was almost temperature independent in the temperature\nrange sufficiently below the superconducting transition but grew as the\ntransition temperature was approached. This temperature dependence suggests\nthat the relaxation of the spin polarization in the superconducting state is\ngoverned by the condensation of quasiparticles to the paired state. The spin\nrelaxation in the superconducting state turned out to be more effective than in\nthe normal state.",
        "positive": "Optical absorption and emission of silicon nanocrystals: From single to\n  collective response: We report on the possibility of describing the absorption and emission\ncharacteristics of an ensemble of silicon nanocrystals (NCs) with realistic\ndistributions in the NC size, by the sum of the reponses of the single NCs. The\nindividual NC responses are evaluated by means of ab-initio theoretical\ncalculations and the summation is performed by taking into account the trend of\nthe optical properties as a function of NC size and oxidation degree. The\ncomparison with experimental results shows a nice matching of the spectra, also\nwithout any tuning of the parameters. Finally, the possibility of adapting the\nmodel in order to reproduce the experimental data is explored and discussed."
    },
    {
        "anchor": "Quantum Kinetic Theory of Thermoelectric and Thermal Transport in a\n  Magnetic Field: We present a general quantum kinetic theory that accounts for the interplay\nbetween a temperature gradient, momentum-space Berry curvatures of Bloch\nelectrons, and Bloch-state scattering. Using a theory that incorporates the\npresence of a temperature gradient by introducing a \"thermal vector potential\",\nwe derive a quantum kinetic equation for Bloch electrons in the presence of\ndisorder and a temperature gradient. Taking also into account the presence of\nelectric and magnetic fields, the quantum kinetic equation we derive makes it\npossible to compute transport coefficients at arbitrary orders of\nelectric-field $\\vec{E}$, magnetic-field $\\vec{B}$, and temperature-gradient\n$\\nabla T$ strengths $|\\vec{E}|^a |\\vec{B}|^b |\\nabla T|^c$. Our theory enables\na systematic calculation of magnetothermoelectric and magnetothermal\nconductivities of systems with momentum-space Berry curvatures. As an\nillustration, we derive from a general microscopic electron model a general\nexpression for the rate of pumping of electrons between valleys in parallel\ntemperature gradient and magnetic field. From this expression we find a\nrelation, which is analogous to the Mott relation, between the rate of pumping\ndue to a temperature gradient and that due to an electric field. We also apply\nour theory to a two-band model for Weyl semimetals to study thermoelectric and\nthermal transport in a magnetic field. We show that the Mott relation is\nsatisfied in the chiral-anomaly induced thermoelectric conductivity, and that\nthe Wiedemann-Franz law is violated in the chiral-anomaly induced thermal\nconductivity, which are both consistent with the results obtained by invoking\nsemiclassical wave-packet dynamics.",
        "positive": "Josephson current in nanofabricated V/Cu/V mesoscopic junctions: We report the successful fabrication of planar V/Cu/V mesoscopic Josephson\nweak-links of different size, and the analysis of their low-temperature\nbehavior. The shorter junctions exhibit critical currents of several tens of\nmicroA at 350 mK, while Josephson coupling persists up to ~2.7 K. Good\nagreement is obtained by comparing the measured switching currents to a model\nwhich holds in the diffusive regime. Our results demonstrate that V is an\nexcellent candidate for the implementation of superconducting nanodevices\noperating at a few kelvins."
    },
    {
        "anchor": "Time-resolved Coulomb collision of single electrons: Precise control over interactions between ballistic electrons will enable us\nto exploit Coulomb interactions in novel ways, to develop high-speed sensing,\nto reach a non-linear regime in electron quantum optics and to realise schemes\nfor fundamental two-qubit operations on flying electrons. Time-resolved\ncollisions between electrons have been used to probe the indistinguishability,\nWigner function and decoherence of single electron wavepackets. Due to the\neffects of screening, none of these experiments were performed in a regime\nwhere Coulomb interactions were particularly strong. Here we explore the\nCoulomb collision of two high energy electrons in counter-propagating ballistic\nedge states. We show that, in this kind of unscreened device, the partitioning\nprobabilities at different electron arrival times and barrier height are shaped\nby Coulomb repulsion between the electrons. This prevents the wavepacket\noverlap required for the manifestation of fermionic exchange statistics but\nsuggests a new class of devices for studying and manipulating interactions of\nballistic single electrons.",
        "positive": "Coupled oscillators model for hybridized optical phonon modes in\n  contacting nanosized particles and quantum dot molecules: Modification of optical phonon spectra in contacting nanoparticles as\ncompared to the single ones is studied. Optical phonons in dielectric and\nsemiconducting particles obey the Euclidean metric Klein-Fock-Gordon equation\nwith Dirichlet boundary conditions. The latter is supposed to be solved\nnumerically for manifolds of interpenetrating spheres. It is proposed to\nreplace this problem with the simpler-to-solve coupled oscillators model (COM),\nwhere an oscillator is attributed to each phonon mode of a particle and the\nparticles overlap leads to appearance of additional couplings for these\noscillators with the magnitude proportional to the overlapped volume. For not\ntoo big overlaps this model describes solutions of the original eigenvalue\nproblem on a good level of accuracy. In particular, it works beyond isotropic s\nmodes, which has been demonstrated for p modes in dimer and also for tetramer.\nIt is proposed to apply COM for the description of recently manufactured dimer\nnanoparticles and quantum dots. The obtained results are in agreement with the\ndynamical matrix method for optical phonons in nanodiamonds. The latter is used\nto demonstrate that the van der Waals contacts between faceted particles lead\nto very small modifications of the optical phonon spectra, which therefore\ncould be neglected when discussing the propagation of vibrational excitations\nvia a nanopowder. The possibility to distinguish between dimerized and\nsize-distributed single particles from their Raman spectra is also considered."
    },
    {
        "anchor": "Even-odd dependent optical transitions of zigzag monolayer black\n  phosphorus nanoribbons: We analytically study the electronic structures and optical properties of\nzigzag-edged black phosphorene nanoribbons (ZPNRs) utilizing the tight-binding\n(TB) Hamiltonian and Kubo formula. By solving the discrete Schordinger equation\ndirectly, we obtain the energy spectra and wavefunctions for a $N$-ZPNR with\n$N$ number of transverse zigzag atomic chains, and classify the eigenstates\naccording to the lattice symmetry. We then obtain the optical transition\nselection rule of ZPNRs based on the symmetry analysis and the analytical\nexpressions of the optical transition matrix elements. Under an incident light\nlinearly-polarized along the ribbon, importantly, we find that the optical\ntransition selection rule for the $N$-ZPNR with even- or odd-$N$ is\nqualitatively different. In specification, for even-$N$ ZPNRs the inter-\n(intra-) band selection rule is $\\Delta n=$odd (even), since the parity of the\nwavefunction corresponding to the $n$th subband in the conduction (valence)\nband is $(-1)^{n}[(-1)^{(n+1)}]$ due to the presence of the $C_{2x}$ symmetry.\nIn contrast, all optical transitions are possible among all subbands due to the\nabsence of the $C_{2x}$ symmetry. Our findings provide a further understanding\non the electronic states and optical properties of ZPNRs, which are useful in\nthe explanation of the optical experiment data on ZPNR samples.",
        "positive": "Fluctuational Electrodynamics in Atomic and Macroscopic Systems: van der\n  Waals Interactions and Radiative Heat Transfer: We present an approach to describing fluctuational electrodynamic (FED)\ninteractions, particularly van der Waals (vdW) interactions as well as\nradiative heat transfer (RHT), between material bodies of vastly different\nlength scales, allowing for going between atomistic and continuum treatments of\nthe response of each of these bodies as desired. Any local continuum\ndescription of electromagnetic (EM) response is compatible with our approach,\nwhile atomistic descriptions in our approach are based on effective electronic\nand nuclear oscillator degrees of freedom, encapsulating dissipation,\nshort-range electronic correlations, and collective nuclear vibrations\n(phonons). While our previous works using this approach have focused on\npresenting novel results, this work focuses on the derivations underlying these\nmethods. First, we show how the distinction between \"atomic\" and \"macroscopic\"\nbodies is ultimately somewhat arbitrary, as formulas for vdW free energies and\nRHT look very similar regardless of how the distinction is drawn. Next, we\ndemonstrate that the atomistic description of material response in our approach\nyields EM interaction matrix elements which are expressed in terms of\nanalytical formulas for compact bodies or semianalytical formulas based on\nEwald summation for periodic media; we use this to compute vdW interaction free\nenergies as well as RHT powers among small biological molecules in the presence\nof a metallic plate as well as between parallel graphene sheets in vacuum,\nshowing strong deviations from conventional macroscopic theories due to the\nconfluence of geometry, phonons, and EM retardation effects. Finally, we\npropose formulas for efficient computation of FED interactions among material\nbodies in which those that are treated atomistically as well as those treated\nthrough continuum methods may have arbitrary shapes, extending previous\nsurface-integral techniques."
    },
    {
        "anchor": "Interaction-Induced Quantum Dephasing in Mesoscopic Rings: Combining nonperturbative techniques with Monte Carlo simulations we\ndemonstrate that quantum coherence effects for a particle on a ring are\nsuppressed beyond a finite length $L_{\\phi}$ even at zero temperature if the\nparticle is coupled to a diffusive electron gas by means of long range Coulomb\ninteraction. This length is consistent with $L_{\\phi}$ derived from\nweak-localization-type of analysis.",
        "positive": "Moir\u00e9 Excitons Correlated with Superlattice Structure in Twisted\n  WSe$_2$/WSe$_2$ Homobilayers: Moir\\'e superlattices in twisted van der Waals materials constitute a\npromising platform for engineering electronic and optical properties. However,\na major obstacle to fully understanding these systems and harnessing their\npotential is the limited ability to correlate the local moir\\'e structure with\noptical properties. By using a recently developed scanning electron microscopy\ntechnique to image twisted WSe$_2$/WSe$_2$ bilayers, we directly correlate\nincreasing moir\\'e periodicity with the emergence of two distinct exciton\nspecies. These can be tuned individually through electrostatic gating, and\nfeature different valley coherence properties. Our observations can be\nunderstood as resulting from an array of two intralayer exciton species\nresiding in alternating locations in the superlattice, and illuminate the\ninfluence of the moir\\'e potential on lateral exciton motion. They open up new\navenues for controlling exciton arrays in twisted TMDs, with applications in\nquantum optoelectronics and explorations of novel many body systems."
    },
    {
        "anchor": "Generalized Peierls substitution for the tight-binding model of twisted\n  multilayer graphene in a magnetic field: We propose a generalized Peierls substitution method in conjunction with the\ntight-binding model to explore the magnetic quantization and quantum Hall\neffect in twisted multilayer graphene under a magnetic field. The Bloch-basis\ntight-binding Hamiltonian is constructed for large twist angle while a\nsimplified tight-binding model is employed for the magic angle. We investigate\nextensively the band structures, Landau levels (LLs), and quantum Hall\nconductivity (QHC) of twisted bilayer graphene and twisted double bilayer\ngraphene, as well as their dependence on the twist angle. Comparison between\nthese crucial properties of monolayer graphene, Bernal bilayer graphene, and\nthe twisted systems is carefully made to highlight the roles played by\ntwisting. The unique selection rules of inter-LL transition, which is crucial\nfor achieving a deep understanding of the step structures of QHC, are\nidentified through the properties of LL wave functions. Our theoretical model\nopens up an opportunity for comprehension of the interplay between an applied\nmagnetic field and the twisting effect associated with multilayer graphene.",
        "positive": "Three-Dimensional Quantum Hall Effect in Topological Amorphous Metals: Weyl semimetals have been theoretically predicted to become topological\nmetals with anomalous Hall conductivity in amorphous systems. However,\nmeasuring the anomalous Hall conductivity in realistic materials, particularly\nthose with multiple pairs of Weyl points, is a significant challenge. If a\nsystem respects time-reversal symmetry, then the anomalous Hall conductivity\neven vanishes. As such, it remains an open question how to probe the Weyl band\nlike topology in amorphous materials. Here, we theoretically demonstrate that,\nunder magnetic fields, a topological metal slab in amorphous systems exhibits\nthree-dimensional quantum Hall effect, even in time-reversal invariant systems,\nthereby providing a feasible approach to exploring Weyl band like topology in\namorphous materials. We unveil the topological origin of the quantized Hall\nconductance by calculating the Bott index. The index is carried by broadened\nLandau levels with bulk states spatially localized except at critical\ntransition energies. The topological property also results in edge states\nlocalized at distinct hinges on two opposite surfaces."
    },
    {
        "anchor": "Carbon Nanotube Millikelvin Transport and Nanomechanics: Single wall carbon nanotubes cooled to cryogenic temperatures are outstanding\nelectronic as well as nano-electromechanical model systems. To probe a largely\nunperturbed system, we measure a suspended carbon-nanotube device where the\nnanotube is grown in the last fabrication step, thus avoiding damage and\nresidues from subsequent processing. In this ultra-clean device, we observe the\ntransport spectrum and its interaction with nano-electromechanics over a wide\ngate voltage range and thereby over a wide range of coupling parameters between\nthe quantum dot and the contact electrodes.",
        "positive": "Flux-tunable Kitaev chain in a quantum dot array: Connecting quantum dots through Andreev bound states in a\nsemiconductor-superconductor hybrid provides a platform to create a Kitaev\nchain. Interestingly, in a double quantum dot, a pair of poor man's Majorana\nzero modes can emerge when the system is fine-tuned to a sweet spot, where\nsuperconducting and normal couplings are equal in magnitude. Control of the\nAndreev bound states is crucial for achieving this, usually implemented by\nvarying its chemical potential. In this work, we propose using Andreev bound\nstates in a narrow Josephson junction to mediate both types of couplings, with\nthe ratio tunable by the phase difference across the junction. Now a minimal\nKitaev chain can be easily tuned into the strong coupling regime by varying the\nphase and junction asymmetry, even without changing the dot-hybrid coupling\nstrength. Furthermore, we identify an optimal sweet spot at $\\pi$ phase,\nenhancing the excitation gap and robustness against phase fluctuations. Our\nproposal introduces a new device platform and a new tuning method for realizing\nquantum-dot-based Kitaev chains."
    },
    {
        "anchor": "The specific heat and the radial thermal expansion of bundles of\n  single-walled carbon nanotubes: The specific heat at constant pressure of bundles of single-walled carbon\nnanotubes closed at their ends has been investigated in a temperature interval\nof 2-120 K. It is found that the curve of heat capacity has features near 5,\n36, 80, and 100 K. The experimental results on the heat capacity and the radial\nthermal expansion coefficient of bundles of SWNTs oriented perpendicular to the\nsample axis have been compared. It is found that the curves of the heat\ncapacity and the radial thermal expansion coefficient exhibit a similar\ntemperature behavior above 10 K. The temperature dependence of the Gruneisen\ncoefficient has been calculated. The curve of the Gruneisen coefficient also\nhas a feature near 36 K. Above 36 K the Gruneisen coefficient is practically\nindependent of temperature. Below 36 K the Gruneisen coefficient decreases\nmonotonically with lowering temperature and becomes negative below 6 K.",
        "positive": "Control of valley polarization in monolayer MoS2 by optical helicity: Electronic and spintronic devices rely on the fact that free charge carriers\nin solids carry electric charge and spin, respectively. There are, however,\nother properties of charge carriers that might be exploited in new families of\ndevices. In particular, if there are two or more conduction (or valence) band\nextrema in momentum space, then confining charge carriers in one of these\nvalleys allows the possibility of valleytronic devices. Such valley\npolarization has been demonstrated by using strain and magnetic fields, but\nneither of these approaches allow for dynamic control. Recently, optical\ncontrol of valley occupancy in graphene with broken inversion symmetry has been\nproposed but remains experimentally difficult to realize. Here we demonstrate\nthat optical pumping with circularly-polarized light can achieve complete\ndynamic valley polarization in monolayer MoS2, a two dimensional (2D)\nnon-centrosymmetric crystal with direct energy gaps at two valleys. Moreover,\nthis polarization is retained for longer than 1 ns. Our results demonstrate the\nviability of optical valley control and valley-based electronic and\noptoelectronic applications in MoS2 monolayers."
    },
    {
        "anchor": "Spin-resolved Quantum Interference in Graphene: The unusual electronic properties of single-layer graphene make it a\npromising material system for fundamental advances in physics, and an\nattractive platform for new device technologies. Graphene's spin transport\nproperties are expected to be particularly interesting, with predictions for\nextremely long coherence times and intrinsic spin-polarized states at zero\nfield. In order to test such predictions, it is necessary to measure the spin\npolarization of electrical currents in graphene. Here, we resolve spin\ntransport directly from conductance features that are caused by quantum\ninterference. These features split visibly in an in-plane magnetic field,\nsimilar to Zeeman splitting in atomic and quantum dot systems. The\nspin-polarized conductance features that are the subject of this work may, in\nthe future, lead to the development of graphene devices incorporating\ninterference-based spin filters.",
        "positive": "Theory of the Half-Polarized Quantum Hall States: We report a theoretical analysis of the half-polarized quantum Hall states\nobserved in a recent experiment. Our numerical results indicate that the ground\nstate energy of the quantum Hall $\\nu= 2/3$ and $\\nu= 2/5$ states versus spin\npolarization has a downward cusp at half the maximal spin polarization. We map\nthe two-component fermion system onto a system of excitons and describe the\nground state as a liquid state of excitons with non-zero values of exciton\nangular momentum."
    },
    {
        "anchor": "Experimental Observation of the Quantum Anomalous Hall Effect in a\n  Magnetic Topological Insulator: The quantized version of the anomalous Hall effect has been predicted to\noccur in magnetic topological insulators, but the experimental realization has\nbeen challenging. Here, we report the observation of the quantum anomalous Hall\n(QAH) effect in thin films of Cr-doped (Bi,Sb)2Te3, a magnetic topological\ninsulator. At zero magnetic field, the gate-tuned anomalous Hall resistance\nreaches the predicted quantized value of h/e^2,accompanied by a considerable\ndrop of the longitudinal resistance. Under a strong magnetic field, the\nlongitudinal resistance vanishes whereas the Hall resistance remains at the\nquantized value. The realization of the QAH effect may lead to the development\nof low-power-consumption electronics.",
        "positive": "Alternating currents and shear waves in viscous electronics: Strong interaction among charge carriers can make them move like viscous\nfluid. Here we explore alternating current (AC) effects in viscous electronics.\nIn the Ohmic case, incompressible current distribution in a sample adjusts fast\nto a time-dependent voltage on the electrodes, while in the viscous case,\nmomentum diffusion makes for retardation and for the possibility of propagating\nslow shear waves. We focus on specific geometries that showcase interesting\naspects of such waves: current parallel to a one-dimensional defect and current\napplied across a long strip. We find that the phase velocity of the wave\npropagating along the strip respectively increases/decreases with the frequency\nfor no-slip/no-stress boundary conditions. This is so because when the\nfrequency or strip width goes to zero (alternatively, viscosity go to\ninfinity), the wavelength of the current pattern tends to infinity in the\nno-stress case and to a finite value in a general case. We also show that for\nDC current across a strip with no-stress boundary, there only one pair of\nvortices, while there is an infinite vortex chain for all other types of\nboundary conditions."
    },
    {
        "anchor": "A universal Hamiltonian for the motion and the merging of Dirac cones in\n  a two-dimensional crystal: We propose a simple Hamiltonian to describe the motion and the merging of\nDirac points in the electronic spectrum of two-dimensional electrons. This\nmerging is a topological transition which separates a semi-metallic phase with\ntwo Dirac cones from an insulating phase with a gap. We calculate the density\nof states and the specific heat. The spectrum in a magnetic field B is related\nto the resolution of a Schrodinger equation in a double well potential. They\nobey the general scaling law e_n \\propto B^{2/3} f_n(Delta /B^{2/3}. They\nevolve continuously from a sqrt{n B} to a linear (n+1/2)B dependence, with a\n[(n+1/2)B]^{2/3} dependence at the transition. The spectrum in the vicinity of\nthe topological transition is very well described by a semiclassical\nquantization rule. This model describes continuously the coupling between\nvalleys associated with the two Dirac points, when approaching the transition.\nIt is applied to the tight-binding model of graphene and its generalization\nwhen one hopping parameter is varied. It remarkably reproduces the low field\npart of the Rammal-Hofstadter spectrum for the honeycomb lattice.",
        "positive": "Quantum thermodynamics of nanoscale thermoelectrics and electronic\n  devices: This mini-review is intended as a short introduction to electron flow in\nnanostructures. Its aim is to provide a brief overview of this topic for people\nwho are interested in the thermodynamics of quantum systems but know little\nabout nanostructures. We particularly emphasize devices that work in the\nsteady-state, such as simple thermoelectrics, but also mention cyclically\ndriven heat engines. We do not aim to be either complete or rigorous, but use a\nfew pages to outline some of the main ideas in the topic."
    },
    {
        "anchor": "Tracing Dirac points of topological surface states by ferromagnetic\n  resonance: Ferromagnetic resonance is used to reveal features of the buried electronic\nband structure at interfaces between ferromagnetic metals and topological\ninsulators. By monitoring the evolution of magnetic damping, the application of\nthis method to a hybrid structure consisting of a ferromagnetic layer and a 3D\ntopological insulator reveals a clear fingerprint of the Dirac point and\nexhibits additional features of the interfacial band structure not otherwise\nobservable. The underlying spin-pumping mechanism is discussed in the framework\nof dissipation of angular momentum by topological surface states (TSSs). Tuning\nof the Fermi level within the TSS was verified both by varying the\nstoichiometry of the topological insulator layer and by electrostatic\nbackgating and the damping values obtained in both cases show a remarkable\nagreement. The high energy resolution of this method additionally allows us to\nresolve the energetic shift of the local Dirac points generated by local\nvariations of the electrostatic potential. Calculations based on the chiral\ntunneling process naturally occurring in TSS agree well with the experimental\nresults.",
        "positive": "Bright single photon emitters with enhanced quantum efficiency in a\n  two-dimensional semiconductor coupled with dielectric nano-antennas: Single photon emitters in atomically-thin semiconductors can be\ndeterministically positioned using strain induced by underlying\nnano-structures. Here, we couple monolayer WSe$_2$ to high-refractive-index\ngallium phosphide dielectric nano-antennas providing both optical enhancement\nand monolayer deformation. For single photon emitters formed on such\nnano-antennas, we find very low (femto-Joule) saturation pulse energies and up\nto 10$^4$ times brighter photoluminescence than in WSe$_2$ placed on\nlow-refractive-index SiO$_2$ pillars. We show that the key to these\nobservations is the increase on average by a factor of 5 in the quantum\nefficiency of the emitters coupled to the nano-antennas. This further allowed\nus to gain new insights into their photoluminescence dynamics, revealing the\nroles of the dark exciton reservoir and Auger processes. We also find that the\ncoherence time of such emitters is limited by intrinsic dephasing processes.\nOur work establishes dielectric nano-antennas as a platform for high-efficiency\nquantum light generation in monolayer semiconductors."
    },
    {
        "anchor": "Magnetic Field Inducing Zeeman Splitting and Anomalous Conductance\n  Reduction of Half-integer Quantized Plateaus in InAs Quantum Wires: We report on magnetic field dependence of half-integer quantized conductance\nplateaus (HQPs) in InAs quantum wires. We observed HQPs at zero applied\nmagnetic field in InAs quantum wires fabricated from a high-quality InAs\nquantum well. The application of in-plane magnetic field causes Zeeman\nsplitting of the HQP features, indicating that the origin of the observed HQP\nis not spontaneous spin polarization. Additionally we observe that conductance\nof the split HQPs decreases gradually as the in-plane magnetic field increases.\nWe finally assume electron-electron interaction as a possible mechanism to\naccount for the zero-field HQPs and the anomalous field dependence.",
        "positive": "Suppression of current in transport through parallel double quantum dots: We report our study of the I-V curves in the transport through the quantum\ndot when an additional quantum dot lying in the Kondo regime is side-connected\nto it. Due to the Kondo scattering off the effective spin on a side-connected\nquantum dot the conductance is suppressed at low temperatures and at low\nsource-drain bias voltages. This zero-bias anomaly is understood as enhanced\nKondo scattering with decreasing temperature."
    },
    {
        "anchor": "Nonlocal orbital magnetism of 3d adatoms deposited on the Pt(111)\n  surface: The orbital magnetic moment is still surprisingly not well understood, in\ncontrast to the spin part. Its description in finite systems, such as isolated\natoms and molecules, is not problematic, but it was only recently that a\nrigorous picture was provided for extended systems. Here we focus on an\nintermediate class of systems: magnetic adatoms placed on a non-magnetic\nsurface. We show that the essential quantity is the ground-state charge current\ndensity, in the presence of spin-orbit coupling, and set out its\nfirst-principles description. This is illustrated by studying the magnetism of\nthe surface Pt electrons, induced by the presence of Cr, Mn, Fe, Co and Ni\nadatoms. A physically appealing partition of the charge current is introduced.\nThis reveals that there is an important nonlocal contribution to the orbital\nmoments of the Pt atoms, extending three times as far from each magnetic adatom\nas the induced spin and local orbital moments. We find that it is as sizable as\nthe latter, and attribute its origin to a spin-orbital susceptibility of the Pt\nsurface, different from the one responsible for the formation of the local\norbital moments.",
        "positive": "Transport through a Strongly Correlated Quantum-Dot with Fano\n  Interference: We present the transport properties of a strongly correlated quantum dot\nattached to two leads with a side coupled non-interacting quantum dot.\nTransport properties are analyzed using the slave boson mean field theory which\nis reliable in the zero temperature and low bias regime. It is found that the\ntransport properties are determined by the interplay of two fundamental\nphysical phenomena,i.e. the Kondo effects and the Fano interference. The linear\nconductance will depart from the unitary limit and the zero bias anomaly will\nbe suppressed in the presence of interdot coupling. The zero bias shot noise\nFano factor increases with the interdot coupling and tends to the Poisson\nvalue. The shot noise Fano factor shows a non-monotonic behavior as a function\nof the interdot coupling for various side dot energy levels."
    },
    {
        "anchor": "Micromagnetic study of a spin-torque oscillator based on a magnetic\n  nano-contact magnetized at an arbitrary angle: The nature of spin wave modes excited by spin-polarized direct current in a\nspin-torque auto-oscillator based on a magnetic nanocontact was studied by a\nmicromagnetic simulation in the case when the external bias magnetic field was\nrotated from the in-plane to perpendicular-to-plane orientation. In qualitative\nagreement with the weakly-nonlinear analytical theory it was found, that at a\ncertain critical angle, an abrupt switching from the self-localized nonlinear\n\"bullet\" mode to a propagating quasi-linear Slonczewski mode takes place, and\nis accompanied by an upward jump in generated microwave frequency. It was,\nalso, found that the analytical theory overestimates the magnitude of a\ncritical magnetization angle, corresponding to the mode switching, and that the\nmagnitude of the frequency jump caused by the mode switching is inversely\nproportional to the nanocontact radius.",
        "positive": "Third-order topological insulator in three-dimensional lattice of\n  magnetic vortices: Recent acoustic and electrical-circuit experiments have reported the\nthird-order (or octupole) topological insulating phase, while its counterpart\nin classical magnetic systems is yet to be realized. Here we explore the\ncollective dynamics of magnetic vortices in three-dimensional breathing\ncuboids, and find that the vortex lattice can support zero-dimensional corner\nstates, one-dimensional hinge states, two-dimensional surface states, and\nthree-dimensional bulk states, when the ratio of alternating intralayer and\ninterlayer bond lengths goes beyond a critical value. We show that only the\ncorner states are stable against external frustrations because of the\ntopological protection. Full micromagnetic simulations verify our theoretical\npredictions with good agreement."
    },
    {
        "anchor": "Purcell effect in small metallic cavities: We have studied theoretically the Purcell factor which characterizes a change\nin the emission rate of an electric or magnetic dipole embedded in the center\nof a spherical cavity. The main attention is paid to the analysis of cavities\nwith radii small compared to the wavelength. It is shown that the Purcell\nfactor in small metallic cavities varies in a wide range depending on the ratio\nof the cavity size to the skin depth.",
        "positive": "Nonlinear Electrodynamics and Optics of Graphene: Graphene is a two-dimensional material with strongly nonlinear\nelectrodynamics and optical properties. We present some of our recent\ntheoretical results on the quantum and non-perturbative quasi-classical\ntheories of nonlinear effects in graphene, influence of substrates on graphene\nnonlinearities, plasma oscillations in graphene in the nonlinear regime and\nother effects."
    },
    {
        "anchor": "Liouvillian Approach to the Integer Quantum Hall Effect Transition: We present a novel approach to the localization-delocalization transition in\nthe integer quantum Hall effect. The Hamiltonian projected onto the lowest\nLandau level can be written in terms of the projected density operators alone.\nThis and the closed set of commutation relations between the projected\ndensities leads to simple equations for the time evolution of the density\noperators. These equations can be used to map the problem of calculating the\ndisorder averaged and energetically unconstrained density-density correlation\nfunction to the problem of calculating the one-particle density of states of a\ndynamical system with a novel action. At the self-consistent mean-field level,\nthis approach yields normal diffusion and a finite longitudinal conductivity.\nWhile we have not been able to go beyond the saddle point approximation\nanalytically, we show numerically that the critical localization exponent can\nbe extracted from the energetically integrated correlation function yielding\n$\\nu=2.33 \\pm 0.05$ in excellent agreement with previous finite-size scaling\nstudies.",
        "positive": "Spin Transfer of Quantum Information between Majorana Modes and a\n  Resonator: We show that resonant coupling and entanglement between a mechanical\nresonator and majorana bound states can be achieved via spin currents in a 1D\nquantum wire with strong spin-orbit interactions. The bound states induced by\nvibrating and stationary magnets can hybridize thus resulting in spin-current\ninduced $4\\pi$-periodic torque, as a function of the relative field angle,\nacting on the resonator. We study the feasibility of detecting and manipulating\nmajorana bound states with the use of magnetic resonance force microscopy\ntechniques."
    },
    {
        "anchor": "Topological Orbital Angular Momentum Hall Current: We show that there is a fundamental difference between spin Hall current and\norbital angular momentum Hall current in Rashba- Dresselhaus spin orbit\ncoupling systems. The orbital angular momentum Hall current has a pure\ntopological contribution which is originated from the existence of magnetic\nflux in momentum space while there is no such topological nature for the spin\nHall current. Moreover, we show that the orbital Hall conductance is always\nlarger than the spin Hall conductance in the presence of both couplings. The\ntopological part is expected to be free from the effect of disorder due to the\ntopological nature. Therefore, the orbital angular momentum Hall current should\nbe the major effect in real experiments.",
        "positive": "Trion-phonon interaction in atomically thin semiconductors: Optical and transport properties of doped monolayer semiconductors are\ndominated by trions, which are three-particle compounds formed by two electrons\nand one hole or vice versa. In this work, we investigate the trion-phonon\ninteraction on a microscopic footing and apply our model to the exemplary case\nof a molybdenum diselenide (MoSe2) monolayer. We determine the trion series of\nstates and their internal quantum structure by solving the trion Schr\\\"odinger\nequation. Transforming the system into a trion basis and solving equations of\nmotion, including the trion-phonon interaction within the second-order\nBorn-Markov approximation, provides a microscopic access to the trion dynamics.\nIn particular, we investigate trion propagation and compute the diffusion\ncoefficient and mobility. In the low density limit, we find that trions\npropagate less efficiently than excitons and electrons due to their stronger\ncoupling with phonons and their larger mass. For increasing densities, we\npredict a drastic enhancement of diffusion caused by the build-up of a large\npressure by the degenerate trion gas, which is a direct consequence of the\nfermionic character of trions. Our work provides microscopic insights into the\ntrion-phonon interaction and its impact on the diffusion behaviour in\natomically thin semiconductors."
    },
    {
        "anchor": "Tunable large Berry dipole in strained twisted bilayer graphene: Recent experiments have measured local uniaxial strain fields in twisted\nbilayer graphene (TBG). Our calculations found that the finite Berry curvature\ngenerated by breaking the sublattice symmetry and the band proximity between\nnarrow bands in these TBG induces a giant Berry dipole of order 10\\,nm or\nlarger. The large Berry dipole leads to transverse topological non-linear\ncharge currents which dominates over the linear bulk valley current at\nexperimentally accessible crossover in-plane electric field of $\\sim 0.1 {\\rm\nmV} / \\mu \\rm{m}$. This anomalous Hall effect, due to Berry dipole, is strongly\ntunable by the strain parameters, electron fillings, gap size, and temperature.",
        "positive": "Full control of quadruple quantum dot circuit charge states in the\n  single electron regime: We report the realization of an array of four tunnel coupled quantum dots in\nthe single electron regime, which is the first required step toward a scalable\nsolid state spin qubit architecture. We achieve an efficient tunability of the\nsystem but also find out that the conditions to realize spin blockade readout\nare not as straightforwardly obtained as for double and triple quantum dot\ncircuits. We use a simple capacitive model of the series quadruple quantum dots\ncircuit to investigate its complex charge state diagrams and are able to find\nthe most suitable configurations for future Pauli spin blockade measurements.\nWe then experimentally realize the corresponding charge states with a good\nagreement to our model."
    },
    {
        "anchor": "Tunneling of Electrons in Graphene via Double Triangular Barrier in\n  External Fields: We study the transmission probability of Dirac fermions in graphene scattered\nby a triangular double barrier potential in the presence of an external\nmagnetic field. Our system made of two triangular potential barrier regions\nseparated by a well region characterized by an energy gap. Solving our\nDirac-like equation and matching the solutions at the boundaries allowed us to\nexpress our transmission and reflection coefficients in terms of transfer\nmatrix. We show in particular that the transmission exhibits oscillation\nresonances that are manifestations of the Klein tunneling effect. The\ntriangular barrier electrostatic field was found to play a key role in\ncontrolling the peak of tunneling resistance. However, it only slightly\nmodifies the resonances at oblique incidence and leaves Klein paradox\nunaffected at normal incidence.",
        "positive": "LDA+U and tight-binding electronic structure of InN nanowires: In this paper we employ a combined {\\it ab initio} and tight-binding approach\nto obtain the electronic and optical properties of hydrogenated InN nanowires.\nWe first discuss InN band structure for the wurtzite structure calculated at\nthe LDA+U level and use this information to extract the parameters needed for\nan empirical tight-binging implementation. These parameters are then employed\nto calculate the electronic and optical properties of InN nanowires in a\ndiameter range that would not be affordable by {\\it ab initio} techniques. The\nreliability of the large nanowires results is assessed by explicitly comparing\nthe electronic structure of a small diameter wire studied both at LDA+U and\ntight-binding level."
    },
    {
        "anchor": "Magnetooptics of layered two-dimensional semiconductors and\n  heterostructures: progress and prospects: Beginning with the 'conventional' two-dimensional (2D) quantum wells (QWs)\nbased on III-V and II-VI semiconductors in the 1970s, to the recent\natomically-thin sheets of van der Waals materials such as 2D semiconducting\ntransition metal dichalcogenides (TMDCs) and 2D magnets, the research in 2D\nmaterials is continuously evolving and providing new challenges. Magnetooptical\nspectroscopy has played a significant role in this area of research, both from\nfundamental physics and technological perspectives. A major challenge in 2D\nsemiconductors such as TMDCs is to understand their spin-valley-resolved\nphysics, and their implications in quantum computation and information\nresearch. Since the discovery of valley Zeeman effects, deep insights into the\nspin-valley physics of TMDCs and their heterostructures has emerged through\nmagnetooptical spectroscopy. In this perspective, we highlight the role of\nmagnetooptics in many milestones such as the discovery of interlayer excitons,\nphase control between coherently-excited valleys, determination of\nexciton-reduced masses, Bohr radii and binding energies, physics of the\noptically-bright and dark excitons, trions, other many-body species such as\nbiexcitons and their phonon replicas in TMDC monolayers. The discussion\naccompanies open questions, challenges and future prospects in the field\nincluding comments on the magnetooptics of van der Waals heterostructures\ninvolving TMDCs and 2D magnets.",
        "positive": "Single electron tunneling through high-Q single-wall carbon nanotube\n  NEMS resonators: By first lithographically fabricating contact electrodes and then as last\nstep growing carbon nanotubes with chemical vapour deposition across the\nready-made chip, many potential contamination mechanisms for nanotube devices\ncan be avoided. Combining this with pre-defined trenches on the chip, such that\nthe nanotubes are freely suspended above the substrate, enables the formation\nof highly regular electronic systems. We show that, in addition, such suspended\nultra-clean nanotubes provide excellent high-frequency and low-dissipation\nmechanical resonators. The motion detection mechanism of our experiment is\ndiscussed, and we measure the effect of Coulomb blockade and the back-action of\nsingle electron tunneling on the mechanical motion. In addition data on the\nmechanical higher modes is presented."
    },
    {
        "anchor": "Excitonic structure and pumping power dependent emission blue-shift of\n  type-II quantum dots: In this work we study theoretically and experimentally the multi-particle\nstructure of the so-called type-II quantum dots with spatially separated\nelectrons and holes. Our calculations based on customarily developed full\nconfiguration interaction approach reveal that exciton complexes containing\nholes interacting with two or more electrons exhibit fairly large antibinding\nenergies. This effect is found to be the hallmark of the type-II confinement.\nIn addition, an approximate self-consistent solution of the multi-exciton\nproblem allows us to explain two pronounced phenomena: the blue-shift of the\nemission with pumping and the large inhomogenous spectral broadening, both of\nthose eluding explanation so far. The results are confirmed by detailed\nintensity and polarization resolved photoluminescence measurements on a number\nof type-II samples.",
        "positive": "Antisymmetric Planar Hall Effect in Rutile Oxide Films Induced by the\n  Lorentz Force: The conventional Hall effect is linearly proportional to the field component\nor magnetization component perpendicular to a film. Despite the increasing\ntheoretical proposals on the Hall effect to the in-plane field or magnetization\nin various special systems induced by the Berry curvature, such an\nunconventional Hall effect has only been experimentally reported in Weyl\nsemimetals and in a heterodimensional superlattice. Here, we report an\nunambiguous experimental observation of the antisymmetric planar Hall effect\n(APHE) with respect to the in-plane magnetic field in centrosymmetric rutile\nRuO2 and IrO2 single-crystal films. The measured Hall resistivity is found to\nbe linearly proportional to the component of the applied in-plane magnetic\nfield along a particular crystal axis and to be independent of the current\ndirection or temperature. Both the experimental observations and theoretical\ncalculations confirm that the APHE in rutile oxide films is induced by the\nLorentz force. Our findings can be generalized to ferromagnetic materials for\nthe discovery of anomalous Hall effects and quantum anomalous Hall effects\ninduced by in-plane magnetization. In addition to significantly expanding\nknowledge of the Hall effect, this work opens the door to explore new members\nin the Hall effect family."
    },
    {
        "anchor": "Effect of Mn doping on ultrafast carrier dynamics in thin films of the\n  topological insulator Bi2Se3: Transient reflectivity (TR) measured at laser photon energy 1.51 eV from the\nindirectly intersurface coupled topological insulator Bi2-xMnxSe3 films (12 nm\nthick) revealed a strong dependence of the rise-time and initial decay-time\nconstants on photoexcited carrier density and Mn content. In undoped samples (x\n= 0), these time constants are exclusively governed by electron-electron and\nelectron-phonon scattering, respectively, whereas in films with x = 0.013 -\n0.27 ultrafast carrier dynamics are completely controlled by photoexcited\nelectron trapping by ionized Mn2+ acceptors and their dimers. The shortest\ndecay-time (~0.75 ps) measured for the film with x = 0.27 suggests a great\npotential of Mn-doped Bi2Se3 films for applications in high-speed\noptoelectronic devices. Using Raman spectroscopy exploiting similar laser\nphoton energy (1.58 eV), we demonstrate that due to indirect intersurface\ncoupling in the films, the photoexcited electron trapping in the bulk enhances\nthe electron-phonon interaction strength in Dirac surface states.",
        "positive": "Thermoelectric response of nodal-line semimetals: probe of the Fermi\n  surface topology: We investigate the low-temperature thermoelectric properties of\nthree-dimensional nodal-line semimetals within the semiclassical Boltzmann\nformalism. Considering short-range interaction between electrons and scattering\nagents, we calculate the anisotropic relaxation times and then obtain the\ncharge conductivity and thermopower along the radial and the axial directions\nwith respect to the nodal-line plane. Increasing the carrier concentration, a\ntopological transition in the shape of the Fermi surface from a torus into an\nellipsoid signal as a sharp change in the thermopower. An adequate treatment of\nthe energy and direction dependence of the relaxation time is necessary for the\nobservation of the topological transition of the Fermi surface in the\nthermoelectric properties."
    },
    {
        "anchor": "Double Fu-teleportation and anomalous Coulomb blockade in a\n  Majorana-hosted superconducting island: We study the temperature dependence of Coulomb Blockade peak conductance\nbased on a Majorana-hosted superconducting island. In the low-temperature\nregime, we discover a coherent double Fu-teleportation (FT) process, where any\nindependent tunneling process always involves two coherent FTs; and we also\nfind an anomalous universal scaling behavior, which shows a transition from a\n[max(T,eV)]^6 to a [max(T,eV)]^3 conductance behavior as increasing energy\nscale. In the high-temperature regime, using the familiar rate equation method,\nwe find that the conductance is proportional to the reciprocal of the\ntemperature and shows a non-monotonic temperature-dependence. Both the\nanomalous power-law behavior and non-monotonic temperature-dependence can be\ndistinguished from the conductance peak in the traditional Coulomb block, and\ntherefore, serve as a hallmark for the non-local transport in the topological\nsuperconducting island.",
        "positive": "Coulomb Drag in Coherent Mesoscopic Systems: We present a theory for Coulomb drag between two mesoscopic systems. Our\nformalism expresses the drag in terms of scattering matrices and wave\nfunctions, and its range of validity covers both ballistic and disordered\nsystems. The consequences can be worked out either by analytic means, such as\nthe random matrix theory, or by numerical simulations. We show that Coulomb\ndrag is sensitive to localized states, which usual transport measurements do\nnot probe. For chaotic 2D-systems we find a vanishing average drag, with a\nnonzero variance. Disordered 1D-wires show a finite drag, with a large\nvariance, giving rise to a possible sign change of the induced current."
    },
    {
        "anchor": "Low-Energy Electron Reflectivity of Graphene on Copper and other\n  Substrates: The reflectivity of low energy electrons from graphene on copper substrates\nis studied both experimentally and theoretically. Well-known oscillations in\nthe reflectivity of electrons with energies 0 - 8 eV above the vacuum level are\nobserved in the experiment. These oscillations are reproduced in theory, based\non a first-principles density functional description of interlayer states\nforming for various thicknesses of multilayer graphene. It is demonstrated that\nn layers of graphene produce a regular series of n-1 minima in the reflectance\nspectra, together with a possible additional minimum associated with an\ninterlayer state forming between the graphene and the substrate. Both (111) and\n(001) orientations of the copper substrates are studied. Similarities in their\nreflectivity spectra arise from the interlayer states, whereas differences are\nfound because of the different Cu band structures along those orientations.\nResults for graphene on other substrates, including Pt(111) and Ir(111), are\nalso discussed.",
        "positive": "Gate-Tunable Graphene Quantum Dot and Dirac Oscillator: We obtain the solution of the Dirac equation in (2+1) dimensions in the\npresence of a constant magnetic field normal to the plane together with a\ntwo-dimensional Dirac-oscillator potential coupling. We study the energy\nspectrum of graphene quantum dot (QD) defined by electrostatic gates. We give\ndiscussions of our results based on different physical settings, whether the\ncyclotron frequency is similar or larger/smaller compared to the oscillator\nfrequency. This defines an effective magnetic field that produces the effective\nquantized Landau levels. We study analytically such field in gate-tunable\ngraphene QD and show that our structure allow us to control the valley\ndegeneracy. Finally, we compare our results with already published work and\nalso discuss the possible applications of such QD."
    },
    {
        "anchor": "Exciton-Polaritons in Artificial Lattices and Electron Transport in\n  Bose-Fermi Hybrid Systems: In this thesis, we study two different aspects of many-particle physics. In\nthe first part, we study the Bose-Einstein condensation of microcavity\nexciton-polaritons in different artificial lattices. Bose-Einstein condensation\nis a quantum phase transition, which allows the system to macroscopically\noccupy its ground state and develop coherence spontaneously. Often studied in\nmicrocavities, which are optical cavities that trap light at specific\nwavelengths, exciton-polaritons are a kind of quasiparticle arising from the\nstrong coupling between quantum well excitons and cavity photons. By\nperiodically aligning cavity pillars in different patterns, one can achieve\ndifferent artificial lattice structures. With this setup, we apply the\ndriven-dissipative Gross-Pitaevskii equations to investigate the different\nconsequences of the condensation by changing the pumping schemes and the design\nof the trapping potentials. Topics include multivalley condensation, phase\nselection and intermittency of exciton-polariton condensation, flat band\ncondensation, and exciton-polariton topological insulators. In the second part\nof this thesis, we focus on the electron-scattering properties of a hybrid\nBose-Fermi system. We consider a system consisting of a spatially separated\ntwo-dimensional electron gas layer and an exciton gas layer that interacts via\nCoulomb forces. We study the temperature dependence of the system's resistivity\nwith this interlayer electron-exciton interaction and compare the results with\nthe electron-phonon interaction.",
        "positive": "Nonlocal thermoelectric detection of interaction and correlations in\n  edge states: We investigate nonequilibrium effects in the transport of interacting\nelectrons in quantum conductors, proposing the nonlocal thermoelectric response\nas a direct indicator of the presence of interactions, nonthermal states and\nthe effect of correlations. This is done by assuming a quantum Hall setup where\ntwo channels (connected to reservoirs at different temperatures) co-propagate\nfor a finite distance, such that a thermoelectrical response is only expected\nif the electron-electron interaction mediates heat exchange between the\nchannels. This way, the nonlocal Seebeck response measures the interaction\nstrength. Considering zero-range interactions, we solve the charge and energy\ncurrents and noises of a non-equilibrium integrable interacting system,\ndetermining the universal interaction-dependent length scale of energy\nequilibration. Further, a setup with two controllable quantum point contacts\nallows thermoelectricity to monitor the interacting system thermalisation as\nwell as the fundamental role of cross-correlations in the heat exchange at\nintermediate length scales."
    },
    {
        "anchor": "Tuning the magnetic properties of Co nanoparticles by Pt capping: We show that by capping Co nanoparticles with small amounts of Pt strong\nchanges of the magnetic properties can be induced. The Co nanoparticles have a\nmean diameter of 2.7 nm. From magnetometry measurements we find that for zero\nand for small amounts of Pt (nominal thickness t(Pt) < 0.7 nm) the\nnanoparticles behave superparamagnetic like. With increasing t(Pt) the blocking\ntemperature is enhanced from 16 up to 108 K. Capping with Pd yields comparable\nresults. However, for values t(Pt) > 1 nm a strongly coupled state is\nencountered resembling a ferromagnet with a T_c approx. 400 K",
        "positive": "Scattering Theory of Mesoscopic Detectors: We consider a two-level system coupled to a mesoscopic two-terminal conductor\nthat acts as measuring device. As a convenient description of the conductor we\nintroduce its scattering matrix. We show how its elements can be used to\ncalculate the relaxation and decoherence rates of the two-level system. Special\nemphasis is laid on the charge screening in the conductor that becomes\nimportant in the many-channel limit. Finally we give some examples that\nillustrate charge screening in different limits."
    },
    {
        "anchor": "Optical antennas driven by quantum tunneling: a key issues review: Analogous to radio- and microwave antennas, optical nanoantennas are devices\nthat receive and emit radiation at optical frequencies. Until recently, the\nrealization of electrically driven optical antennas was an outstanding\nchallenge in nanophotonics. In this review we discuss and analyze recent\nreports in which quantum tunneling-specifically inelastic electron tunneling-is\nharnessed as a means to convert electrical energy into photons, mediated by\noptical antennas. To aid this analysis we introduce the fundamentals of optical\nantennas and inelastic electron tunneling. Our discussion is focused on recent\nprogress in the field and on future directions and opportunities.",
        "positive": "Confinement of Vibrational Modes in Nanocrystalline Silicon: It is possible to confine vibrational modes to silicon nanocrystals by\nencapsulating them within hydrogenated amorphous silicon. This is not because\nof the small impedance mismatch between materials but, rather, is due to higher\norder moments in the distribution of density and stiffness in the amorphous\nphase--i.e. it is a result of material substructure. The concept is elucidated\nusing an idealized one-dimensional setting and then demonstrated for a\nrealistic nanocrystalline geometry. Beyond the immediate focus on amorphous\nencapsulation, this offers the prospect of specifically engineering higher\norder property distributions as an alternate means of managing phonons. The\napproach could be applied, for instance, to design deterministically ordered\nmaterials which exploit this means of control."
    },
    {
        "anchor": "Treatment of backscattering in a gas of interacting fermions confined to\n  a one-dimensional harmonic atom trap: An asymptotically exact many body theory for spin polarized interacting\nfermions in a one-dimensional harmonic atom trap is developed using the\nbosonization method and including backward scattering. In contrast to the\nLuttinger model, backscattering in the trap generates one-particle potentials\nwhich must be diagonalized simultaneously with the two-body interactions.\nInclusion of backscattering becomes necessary because backscattering is the\ndominant interaction process between confined identical one-dimensional\nfermions. The bosonization method is applied to the calculation of one-particle\nmatrix elements at zero temperature. A detailed discussion of the validity of\nthe results from bosonization is given, including a comparison with direct\nnumerical diagonalization in fermionic Hilbert space. A model for the\ninteraction coefficients is developed along the lines of the Luttinger model\nwith only one coupling constant $K$. With these results, particle densities,\nthe Wigner function, and the central pair correlation function are calculated\nand displayed for large fermion numbers. It is shown how interactions modify\nthese quantities. The anomalous dimension of the pair correlation function in\nthe center of the trap is also discussed and found to be in accord with the\nLuttinger model.",
        "positive": "Bulk-edge correspondence and long range hopping in the topological\n  plasmonic chain: The existence of topologically protected edge modes is often cited as a\nhighly desirable trait of topological insulators. However, these edge states\nare not always present. A realistic physical treatment of long range hopping in\na one-dimensional dipolar system can break the symmetry that protects the edge\nmodes without affecting the bulk topological number, leading to a breakdown in\nbulk-edge correspondence. It is important to find a better understanding of\nwhere and how this occurs, as well as how to measure it. Here we examine the\nbehaviour of the bulk and edge modes in a dimerised chain of metallic\nnanoparticles and in a simpler non-Hermitian next-nearest-neighbour model to\nprovide some insight into the phenomena of bulk-edge breakdown. We construct\nbulk-edge correspondence phase diagrams for the simpler case and use these\nideas to devise a measure of symmetry-breaking for the plasmonic system based\non its bulk properties. This provides a parameter regime for which bulk-edge\ncorrespondence is preserved in the topological plasmonic chain, as well as a\nframework for assessing this phenomenon in other systems."
    },
    {
        "anchor": "First-principles approach to excitons in time-resolved and\n  angle-resolved photoemission spectra: We show that any {\\em quasi-particle} or GW approximation to the self-energy\ndoes not capture excitonic features in time-resolved (TR) photoemission\nspectroscopy. In this work we put forward a first-principles approach and\npropose a feasible diagrammatic approximation to solve this problem. We also\nderive an alternative formula for the TR photocurrent which involves a single\ntime-integral of the lesser Green's function. The diagrammatic approximation\napplies to the {\\em relaxed} regime characterized by the presence of\nquasi-stationary excitons and vanishing polarization. The main distinctive\nfeature of the theory is that the diagrams must be evaluated using {\\em\nexcited} Green's functions. As this is not standard the analytic derivation is\npresented in detail. The final result is an expression for the lesser Green's\nfunction in terms of quantities that can all be calculated {\\em ab initio}. The\nvalidity of the proposed theory is illustrated in a one-dimensional model\nsystem with a direct gap. We discuss possible scenarios and highlight some\nuniversal features of the exciton peaks. Our results indicate that the exciton\ndispersion can be observed in TR {\\em and} angle-resolved photoemission.",
        "positive": "Strain Controlled Spin and Charge Pumping in Graphene Devices via\n  Spin-orbit Coupled Barriers: We theoretically propose a graphene-based adiabatic quantum pump with\nintrinsic spin-orbit coupling (SOC) subject to strain where two time-dependent\nextrinsic spin-orbit coupled barriers drive spin and charge currents. We study\nthree differing operation modes where i) location, ii) chemical potential, and\niii) SOC of the two barriers oscillate periodically and out of phase around\ntheir equilibrium states. Our results demonstrate that the amplitude of\nadiabatically pumped currents highly depends on the considered operation mode.\nWe find that such a device operates with highest efficiency and in a broader\nrange of parameters where the barriers chemical potential drives the quantum\npump. Our results also reveal that by introducing strain to the system, one can\nsuppress or enhance the charge and spin currents separately, depending on\nstrain direction."
    },
    {
        "anchor": "Emergence of a negative charging energy in a metallic dot capacitively\n  coupled to a superconducting island: We consider the hybrid setup formed by a metallic dot, capacitively coupled\nto a superconducting island S connected to a bulk superconductor by a Josephson\njunction. Charge fluctuations in S act as a dynamical gate and overscreen the\nelectronic repulsion in the metallic dot, producing an attractive interaction\nbetween two additional electrons. As the offset charge of the metallic dot is\nincreased, the dot charging curve shows positive steps ($+2e$) followed by\nnegative ones ($-e$) signaling the occurrence of a negative differential\ncapacitance. A proposal for experimental detection is given, and potential\napplications in nanoelectronics are mentioned.",
        "positive": "Unusual spin-wave dynamics in core-shell magnetic nanodisks: We investigated the spin dynamics of a vortex state in a core-shell magnetic\nnanodisk driven by an oscillating field applied perpendicular to the disk plane\nby means of micromagnetic simulations. The nanodisk comprises a Py (Fe0.2Ni0.8)\ncore of 100 nm in radius, surrounded by a 50 nm thick Fe shell. Fourier\ntransform analyses show that the Py core and the Fe shell dominate spin-wave\noscillation at the fundamental and higher order radial modes, respectively. For\noscillating driving field tuned to the fundamental eigenfrequency, the Py/Fe\ninterface effectively confines spin-wave excitation in the Py core region. This\neffect leads to significantly more rapid vortex core (VC) reversal in\ncomparison to homogeneous disks. Our work demonstrates that the higher order\nmodes can drive much faster VC reversal than the fundamental mode, in sharp\ncontrast to the results obtained in homogeneous disks. With excitation levels\nup to 30 mT, we find strong nonlinear spin-wave dynamics in the system, which\nresults in mode frequency redshifting, therefore the observation of the most\nrapid VC reversals below eigenfrequencies and VC switching in wide ranges of\nfrequencies."
    },
    {
        "anchor": "Suspended graphene devices with local gate control on an insulating\n  substrate: We present a fabrication process for graphene-based devices where a graphene\nmonolayer is suspended above a local metallic gate placed in a trench. As an\nexample we detail the fabrication steps of a graphene field-effect transistor.\nThe devices are built on a bare high-resistivity silicon substrate. At\ntemperatures of 77~K and below, we observe the field-effect modulation of the\ngraphene resistivity by a voltage applied to the gate. This fabrication\napproach enables new experiments involving graphene-based superconducting\nqubits and nano-electromechanical resonators. The method is applicable to other\ntwo-dimensional materials.",
        "positive": "Non-equilibrium steady-states for interacting open systems: exact\n  results: Under certain conditions we prove the existence of a steady-state transport\nregime for interacting mesoscopic systems coupled to reservoirs (leads). The\npartitioning and partition-free scenarios are treated on an equal footing. Our\ntime-dependent scattering approach is {\\it exact} and proves, among other\nthings the independence of the steady-state quantities from the initial state\nof the sample. Closed formulas for the steady-state current amenable for\nperturbative calculations w.r.t. the interaction strength are also derived. In\nthe partitioning case we calculate the first order correction and recover the\nmean-field (Hartree-Fock) results."
    },
    {
        "anchor": "Networks of quantum nanorings: programmable spintronic devices: An array of quantum rings with local (ring by ring) modulation of the spin\norbit interaction (SOI) can lead to novel effects in spin state transformation\nof electrons. It is shown that already small (3x3, 5x5) networks are remarkably\nversatile from this point of view: Working in a given network geometry, the\ninput current can be directed to any of the output ports, simply by changing\nthe SOI strengths by external gate voltages. Additionally, the same network\nwith different SOI strengths can be completely analogous to the Stern-Gerlach\ndevice, exhibiting spatial-spin entanglement.",
        "positive": "Hard gap in a normal layer coupled to a superconductor: The ability to induce a sizable gap in the excitation spectrum of a normal\nlayer placed in contact with a conventional superconductor has become\nincreasingly important in recent years in the context of engineering a\ntopological superconductor. The quasiclassical theory of the proximity effect\nshows that Andreev reflection at the superconductor/normal interface induces a\nnonzero pairing amplitude in the metal but does not endow it with a gap.\nConversely, when the normal layer is atomically thin, the tunneling of Cooper\npairs induces an excitation gap that can be as large as the bulk gap of the\nsuperconductor. We study how these two seemingly different views of the\nproximity effect evolve into one another as the thickness of the normal layer\nis changed. We show that a fully quantum-mechanical treatment of the problem\npredicts that the induced gap is always finite but falls off with the thickness\nof the normal layer, $d$. If $d$ is less than a certain crossover scale, which\nis much larger than the Fermi wavelength, the induced gap is comparable to the\nbulk gap. As a result, a sizable excitation gap can be induced in normal layers\nthat are much thicker than the Fermi wavelength."
    },
    {
        "anchor": "Anomalous transport phenomena from dissipative charge pumping: The Berry curvature involving time and momentum derivatives, which we term\nemergent electric field, induces a nondisspative current known as the adiabatic\ncharge pumping or Thouless pumping in periodically driven systems. We study\ndissipative currents originated from the interplay between emergent electric\nfields and electric/magnetic fields in two and three dimensions on the basis of\nthe Boltzmann transport theory. As an example of two-dimensional models, we\nstudy the Rashba Hamiltonian with time-dependent and anisotropic spin-orbit\ncoupling. We show that the interplay between emergent electric fields and\nelectric fields leads to a current transverse to electric fields, which is\nsymmetric and contributes to the entropy production. As an example of\nthree-dimensional models, we study the Weyl Hamiltonian under AC electric\nfields. We show that the interplay between emergent electric fields and\nmagnetic fields leads to a Hall-type current at zero DC electric fields, which\nis now transverse to DC magnetic fields: $j_{x}=\\sigma_{xy}B_y$\n($\\sigma_{xy}=-\\sigma_{yx}$). The Hall photocurrent is relevant in the\ninversion symmetry breaking Weyl semimetals such as TaAs or SrSi$_2$.",
        "positive": "Comprehensive characterization of an individual carbon nanotube\n  transport device: We present a comprehensive characterization of an individual multiwalled\ncarbon nanotube transport device combining electron microscopy and Raman\nspectroscopy with electrical measurements. Each method gives complementary\ninformation that mutually help to interpret each other. A sample design that\nallows for combining these investigation methods on individual carbon nanotube\ndevices is introduced. This offers a direct correlation of transport features\nand shifts of Raman modes with structural properties as e.g. the contact\ninterface and the morphology of the nanotube."
    },
    {
        "anchor": "Magnetic-field Manipulation of Chemical Bonding in Artificial Molecules: The effect of orbital magnetism on the chemical bonding of lateral,\ntwo-dimensional artificial molecules is studied in the case of a 2e double\nquantum dot (artificial molecular hydrogen). It is found that a perpendicular\nmagnetic field reduces the coupling (tunneling) between the individual dots\nand, for sufficiently high values, it leads to complete dissociation of the\nartificial molecule. The method used is building on Lowdin's work on Projection\nOperators in Quantum Chemistry; it is a spin-and-space unrestricted\nHartree-Fock method in conjunction with the companion step of the restoration\nof spin and space symmetries via Projection Techniques (when such symmetries\nare broken). This method is able to describe the full range of couplings in\ntwo-dimensional double quantum dots, from the strong-coupling regime exhibiting\ndelocalized molecular orbitals to the weak-coupling and dissociation regimes\nassociated with a Generalized Valence Bond combination of atomic-type orbitals\nlocalized on the individual dots.",
        "positive": "Quantum phase diffusion in ac-driven superconducting atomic point\n  contacts: The impact of quantum fluctuations on the phase diffusion in resistively\nshunted superconducting quantum points subject to an external ac-voltage is\nstudied. Based on an extension of the classical Smoluchowski equation to the\nquantum regime, numerical results for fractional and integer Shapiro resonances\nare investigated to reveal characteristic features of quantum effects. It is\nshown that typically in the quantum regime the broadening of resonances cannot\nbe described simply by an effective temperature."
    },
    {
        "anchor": "Response to polarization and weak topology in Chern insulators: Chern insulators present a topological obstruction to a smooth gauge in their\nBloch wave functions that prevents the construction of exponentially-localized\nWannier functions - this makes the electric polarization ill-defined. Here, we\nshow that spatial or temporal differences in polarization within Chern\ninsulators are well-defined and physically meaningful because they account for\nbound charges and adiabatic currents. We further show that the difference in\npolarization across Chern-insulator regions can be quantized in the presence of\ncrystalline symmetries, leading to \"weak\" symmetry-protected topological\nphases. These phases exhibit charge fractional quantization at the edge and\ncorner interfaces and with concomitant topological states. We also generalize\nour findings to quantum spin-Hall insulators and 3D topological insulators. Our\nwork settles a long-standing question and deems the bulk polarization as the\nfundamental quantity with a \"bulk-boundary correspondence\", regardless of\nwhether a Wannier representation is possible.",
        "positive": "Linear and planar molecules formed by coupled P donors in silicon: Using the effective mass theory and the multi-valley envelope function\nrepresentation, we have developed a theoretical framework for computing the\nsingle-electron electronic structure of several phosphorus donors interacting\nin an arbitrary geometrical configuration in silicon taking into account the\nvalley-orbit coupling. The methodology is applied to three coupled phosphorus\ndonors, arranged in a linear chain and in a triangle, and to six donors\narranged in a regular hexagon. The results of the simulations evidence that the\nvalley composition of the single-electron states strongly depends on the\ngeometry of the dopant molecule and its orientation relative to the\ncrystallographic axes of silicon. The electron binding energy of the triatomic\nlinear molecules is larger than that of the diatomic molecule oriented along\nthe same crystallographic axis, but the energy gap between the ground state and\nthe first excited state is not significantly different for internuclear\ndistances from 1.5 to 6.6 nm. Three donor atoms arranged in a triangle geometry\nhave larger binding energies than a triatomic linear chain of dopants with the\nsame internuclear distances. The planar donor molecules are characterized by a\nstrong polarization in favor of the valleys oriented perpendicular to the plane\nof the molecule. The polarization increases with number of atoms forming the\nplanar molecule."
    },
    {
        "anchor": "Rotating Entangled States of an Exchange-Coupled Dimer of\n  Single-Molecule Magnets: An antiferromagnetically exchange-coupled dimer of single molecule magnets\nwhich possesses a large spin tunneling has been investigated. For this system\nthe ground and first excited states are entangled states and the Hamiltonian is\neffectively similar to that of a two-state system at $2s^{\\text{th}}$ order in\nperturbation theory, thus this system can be mapped to an entangled pseudospin\n1/2 particles. We study the effects of interaction and rotation of this system\nabout its staggered easy-axis direction . The corresponding Hamiltonian of a\nrotated two-state entangled spin system is derived with its exact low-energy\neigenstates and eigenvalues. We briefly discuss the effect of a dissipative\nenvironment on this rotated two-state system.",
        "positive": "Equilibrium properties of mesoscopic quantum conductors: Review article on equilibrium properties of mesoscopic quantum conductors."
    },
    {
        "anchor": "Ultrasensitive magnetic field detection using a single artificial atom: Efficient detection of magnetic fields is central to many areas of research\nand has important practical applications ranging from materials science to\ngeomagnetism. High sensitivity detectors are commonly built using direct\ncurrent-superconducting quantum interference devices (DC-SQUIDs) or atomic\nsystems. Here we use a single artificial atom to implement an ultrahigh\nsensitivity magnetometer with a size in the micron range. The artificial atom\nis a superconducting two-level system at low temperatures, operated in a way\nsimilar to atomic magnetometry. The high sensitivity results from quantum\ncoherence combined with strong coupling to magnetic field. By employing\nprojective measurements, we obtain a sensitivity of $2.7\\,\n\\t{pT}/\\sqrt{\\t{Hz}}$ at 10 MHz. We discuss feasible improvements that will\nincrease the sensitivity by over one order of magnitude. The intrinsic\nsensitivity of this method to AC fields in the 100 kHz - 10 MHz range compares\nfavourably with DC-SQUIDs and atomic magnetometers of equivalent spatial\nresolution. This result illustrates the potential of artificial quantum systems\nfor sensitive detection and related applications.",
        "positive": "Strain-induced bound states in transition-metal dichalcogenide bubbles: We theoretically study the formation of single-particle bound states confined\nby strain at the center of bubbles in monolayers of transition-metal\ndichalcogenides (TMDs). Bubbles ubiquitously form in two-dimensional crystals\non top of a substrate by the competition between van der Waals forces and the\nhydrostatic pressure exerted by trapped fluid. This leads to strong strain at\nthe center of the bubble that reduces the bangap locally, creating potential\nwells for the electrons that confine states inside. We simulate the spectrum\nversus the bubble radius for the four semiconducting group VI TMDs, MoS$_2$,\nWSe$_2$, WS$_2$ and MoSe$_2$, and find an overall Fock-Darwin spectrum of\nbubble bound states, characterised by small deviations compatible with Berry\ncurvature effects. We analyse the density of states, the state degeneracies,\norbital structure and optical transition rules. Our results show that elastic\nbubbles in these materials are remarkably efficient at confining photocarriers."
    },
    {
        "anchor": "Quasiclassical theory of electronic transport in mesoscopic systems:\n  Luttinger liquids revisited: The method of the quasiclassical Green's function is used to determine the\nequilibrium properties of one-dimensional (1D) interacting Fermi systems, in\nparticular, the bulk and the local (near a hard wall) density of states. While\nthis is a novel approach to 1D systems, our findings do agree with standard\nresults for Luttinger liquids obtained with the bosonization method. Analogies\nto the so-called $P(E)$ theory of tunneling through ultrasmall junctions are\npointed out and are exploited. Further applications of the Green's function\nmethod for 1D systems are discussed.",
        "positive": "Thermal effects and switching kinetics in silver/manganite memristive\n  systems: Probing oxygen vacancies diffusion: We investigate the switching kinetics of oxygen vacancies (Ov) diffusion in\nLPCMO-Ag memristive interfaces by performing experiments on the temperature\ndependence of the high resistance (HR) state under thermal cycling.\nExperimental results are well reproduced by numerical simulations based on\nthermally activated Ov diffusion processes and fundamental assumptions relying\non a recent model proposed to explain bipolar resistive switching in manganite-\nbased cells. The confident values obtained for activation energies and\ndiffusion coefficient associated to Ov dynamics, constitute a validation test\nfor both model predictions and Ov diffusion mechanisms in memristive\ninterfaces."
    },
    {
        "anchor": "Chiral heat transport in driven quantum Hall and quantum spin Hall edge\n  states: We consider a model for an edge state of electronic systems in the quantum\nHall regime with filling $\\nu=1$ and in the quantum spin Hall regime. In both\ncases the system is in contact with two reservoirs by tunneling at point\ncontacts. Both systems are locally driven by applying an ac voltage in one of\nthe contacts. By weakly coupling them to a third reservoir, the transport of\nthe generated heat is studied in two different ways: i) when the third\nreservoir acts as a thermometer the local temperature is sensed, and ii) when\nthe third reservoir acts as a voltage probe the time-dependent local voltage is\nsensed. Our results indicate a chiral propagation of the heat along the edge in\nthe quantum Hall case and in the quantum spin Hall case (if the injected\nelectrons are spin polarized). We also show that a similar picture is obtained\nif instead of heating by ac driving the system is put in contact to a\nstationary reservoir at a higher temperature. In both cases the temperature\nprofile shows that the electrons along the edge thermalize with the closest\n\"upstream\" reservoir.",
        "positive": "Persistent Skyrmion Lattice of Noninteracting Electrons with Spin-Orbit\n  Coupling: A persistent spin helix (PSH) is a robust helical spin-density pattern\narising in disordered 2D electron gases with Rashba $\\alpha$ and Dresselhaus\n$\\beta$ spin-orbit (SO) tuned couplings, i.e., $\\alpha=\\pm\\beta$. Here we\ninvestigate the emergence of a Persistent Skyrmion Lattice (PSL) resulting from\nthe coherent superposition of PSHs along orthogonal directions -- crossed PSHs\n-- in wells with two occupied subbands $\\nu=1,2$. For realistic GaAs wells we\nshow that the Rashba $\\alpha_\\nu$ and Dresselhaus $\\beta_\\nu$ couplings can be\nsimultaneously tuned to equal strengths but opposite signs, e.g., $\\alpha_1=\n\\beta_1$ and $\\alpha_2=-\\beta_2$. In this regime and away from band\nanticrossings, our {\\it non-interacting} electron gas sustains a topologically\nnon-trivial skyrmion-lattice spin-density excitation, which inherits the\nrobustness against spin-independent disorder and interactions from its\nunderlying crossed PSHs. We find that the spin relaxation rate due to the\ninterband SO coupling is comparable to that of the cubic Dresselhaus term as a\nmechanism of the PSL decay. Near anticrossings, the interband-induced spin\nmixing leads to unusual spin textures along the energy contours beyond those of\nthe Rahsba-Dresselhaus bands. Our PSL opens up the unique possibility of\nobserving topological phenomena, e.g., topological and skyrmion Hall effects,\nin ordinary GaAs wells with non-interacting electrons."
    },
    {
        "anchor": "Projection operator approach to lifetimes of electrons in metals: We present an alternative approach to the calculation of the lifetime of a\nsingle excited electron (hole) which interacts with the Fermi sea of electrons\nin a metal. The metal is modelled on the level of a Hamilton operator\ncomprising a pertinent dispersion relation and scattering term. To determine\nthe full relaxation dynamics we employ an adequate implementation of the\ntime-convolutionless projection operator method (TCL). This yields an analytic\nexpression for the decay rate which allows for an intuitive interpretation in\nterms of scattering events. It may furthermore be efficiently evaluated by\nmeans of a Monte-Carlo integration scheme. As an example we investigate\naluminium using, just for simplicity, a jellium-type model. This way we obtain\ndata which are directly comparable to results from a self-energy formalism. Our\napproach applies to arbitrary temperatures.",
        "positive": "Andreev reflection in s-type superconductor proximized 3D topological\n  insulator: We investigate transport and shot noise in lateral N-TI-S contacts, where N\nis a normal metal, TI is a Bi-based three dimensional topological insulator (3D\nTI), and S is an s-type superconductor. In normal state, the devices are in the\nelastic diffusive transport regime, as demonstrated by a nearly universal value\nof the shot noise Fano factor $F_{\\rm N}\\approx1/3$ in magnetic field and in\nreference normal contact. In the absence of magnetic field, we identify the\nAndreev reflection (AR) regime, which gives rise to the effective charge\ndoubling in shot noise measurements. Surprisingly, the Fano factor $F_{\\rm\nAR}\\approx0.22\\pm0.02$ is considerably reduced in the AR regime compared to\n$F_{\\rm N}$, in contrast to previous AR experiments in normal metals and\nsemiconductors. We suggest that this effect is related to a finite thermal\nconduction of the proximized, superconducting TI owing to a residual density of\nstates at low energies."
    },
    {
        "anchor": "Rashba-controlled thermal valve in helical liquids: In the context of one-dimensional fermionic systems, helical Luttiger liquids\nare not only characterized by intriguing spin properties, but also by the\npossibility to be manipulated by means of electrostatic gates, exploiting\nfinite Rashba coupling. We use this property to show that a heterostructure\ncomposed of a helical Luttinger liquid, contacted to two metallic leads and\nsupplemented by top gates, can be used as a tunable thermal valve. By relying\non bosonization techniques and scattering of plasmonic modes, we investigate\nthe performance of this valve with respect to electron-electron interactions,\ntemperature, and properties of the gates. The maximal modulation of the thermal\nconductance that the proposed device can achieve is, for experimentally\nrelevant parameters, around $7 \\%$. Such variation can be both positive or\nnegative. Moreover, a modification in the geometry of the gate can lead to\nparticular temperature dependencies related to interference effects. We also\nargue that the effects we predict can be used to establish the helical nature\nof the edge states in two-dimensional topological insulators.",
        "positive": "Resonant Tunneling and Persistent Current of a Non-interacting and\n  Weakly Interacting One-dimensional Electron Gas: The persistent current for a one-dimensional ring with two tunnel barriers is\nconsidered in the limit of weakly interacting electrons. In addition to a small\noff-resonance current, there are two kinds of resonant behavior; (i) a current\nindependent of the barrier transparency (true resonance) and (ii) a current\nanalogous to the one for a ring with only a single barrier\n(``semi''-resonance). For a given barrier transparency one or the other type of\nresonant behavior is realized depending on a geometric factor (ratio of\ninterbarrier distance to ring circumference) and on the strength of the\nelectron-electron interaction. It is shown that a repulsive interaction favours\nthe``semi''-resonance behavior. For a small barrier transparency the\n``semi''-resonance peaks are easily washed out by temperature whereas the true\nresonance peaks survive."
    },
    {
        "anchor": "Properties of BC$_6$N monolayer derived by first-principle computation:\n  Influences of interactions between dopant atoms: The properties of graphene-like BC$_6$N semiconductor are studied using\ndensity functional theory taking into account the attractive interaction\nbetween B and N atoms. In the presence of a strong attractive interaction\nbetween B and N dopant atoms, the electron charge distribution is highly\nlocalized along the B-N bonds, while for a weaker attractive interaction the\nelectrons are delocalized along the entire hexagonal ring of BC$_6$N.\nFurthermore, when both B and N atoms are doped at the same site of the hexagon,\nthe breaking of the sub-lattice symmetry is low producing a small bandgap. In\ncontrast, if the dopant atoms are at different sites, a high sub-lattice\nsymmetry breaking is found leading to a large bandgap. The influences of\nelectron localization/delocalization and the tunable bandgap on thermal\nbehaviors such as the electronic thermal conductivity, the Seebeck coefficient,\nand the figure of merit, and optical properties such as the dielectric\nfunction, the excitation spectra, the refractive index, the electron energy\nloss spectra, the reflectivity, and the optical conductivity are presented. An\nenhancement with a red shift of the optical conductivity at low energy range is\nseen while a reduction at the high energy range is found indicating that the\nBC$_6$N structure may be useful for optoelectronic devices in the low energy,\nvisible range.",
        "positive": "Bulk and sub-surface donor bound excitons in silicon under electric\n  fields: The electronic structure of the three-particle donor bound exciton (D$^0$X)\nin silicon is computed using a large-scale atomic orbital tight-binding method\nwithin the Hartree approximation. The calculations yield a transition energy\nclose to the experimentally measured value of 1150 meV in bulk, and show how\nthe transition energy and transition probability can change with applied fields\nand proximity to surfaces, mimicking the conditions of realistic devices. The\nspin-resolved transition energy from a neutral donor state (D$^0$) to D$^0$X\ndepends on the three-particle Coulomb energy, and the interface and electric\nfield induced hyperfine splitting and heavy-hole-light-hole splitting. Although\nthe Coulomb energy decreases as a result of Stark shift, the spatial separation\nof the electron and hole wavefunctions by the field also reduces the transition\ndipole. A bulk-like D$^0$X dissociates abruptly at a modest electric field,\nwhile a D$^0$X at a donor close to an interface undergoes a gradual ionization\nprocess. Our calculations take into account the full bandstructure of silicon\nand the full energy spectrum of the donor including spin directly in the atomic\norbital basis and treat the three-particle Coulomb interaction\nself-consistently to provide quantitative guidance to experiments aiming to\nrealize hybrid opto-electric techniques for addressing donor qubits."
    },
    {
        "anchor": "Chirality driven anomalous Hall effect in weak coupling regime: Anomalous Hall effect arising from non-trivial spin configuration (chirality)\nis studied based on the $s$-$d$ model. Considering a weak coupling case, the\ninteraction is treated perturbatively. Scattering by normal impurities is\nincluded. Chirality is shown to drive locally Hall current and leads to overall\nHall effect if there is a finite uniform chirality. This contribution is\nindependent of the conventional spin-orbit contribution and shows distinct low\ntemperature behavior. In mesoscopic spin glasses, chirality-induced anomalous\nHall effect is expected below the spin-glass transition temperature.\nMeasurement of Hall coefficient would be useful in experimentally confirming\nthe chirality ordering.",
        "positive": "Charge and energy fractionalization mechanism in one-dimensional\n  channels: We study the problem of injecting single electrons into interacting\none-dimensional quantum systems, a fundamental building block for electron\nquantum optics. It is well known that such injection leads to charge and energy\nfractionalization. We elucidate this concept by calculating the nonequilibrium\nelectron distribution function in the momentum and energy domains after the\ninjection of an energy-resolved electron. Our results shed light on how\nfractionalization occurs via the creation of particle-hole pairs by the\ninjected electron. In particular, we focus on systems with a pair of\ncounterpropagating channels, and we fully analyze the properties of each chiral\nfractional excitation which is created by the injection. We suggest possible\nroutes to access their energy and momentum distribution functions in\ntopological quantum Hall or quantum spin-Hall edge states."
    },
    {
        "anchor": "Density of states measurements for heavy subband of holes in HgTe\n  quantum wells: Valence band in narrow HgTe quantum wells contains well-conductive Dirac-like\nlight holes at the $\\Gamma$ point and poorly conductive heavy hole subband\nlocated in the local valleys. Here we propose and employ two methods to measure\nthe density of states for these heavy holes. The first method uses a\ngate-recharging technique to measure thermodynamical entropy per particle. As\nthe Fermi level is tuned with gate voltage from light to heavy subband, the\nentropy increases dramatically, and the value of this increase gives an\nestimate for the density of states. The second method determines the density of\nstates for heavy holes indirectly from the gate voltage dependence of the\nperiod of the Shubnikov-de Haas oscillations for light holes. The results\nobtained by both methods are in the reasonable agreement with each other. Our\napproaches can be applied to measure large effective carrier masses in other\ntwo-dimensional gated systems.",
        "positive": "Bound states in the continuum in open Aharonov-Bohm rings: Using formalism of effective Hamiltonian we consider bound states in\ncontinuum (BIC). They are those eigen states of non-hermitian effective\nHamiltonian which have real eigen values. It is shown that BICs are orthogonal\nto open channels of the leads, i.e. disconnected from the continuum. As a\nresult BICs can be superposed to transport solution with arbitrary coefficient\nand exist in propagation band. The one-dimensional Aharonov-Bohm rings that are\nopened by attaching single-channel leads to them allow exact consideration of\nBICs. BICs occur at discrete values of energy and magnetic flux however it's\nrealization strongly depend on a way to the BIC's point."
    },
    {
        "anchor": "Coulomb drag and counterflow Seebeck coefficient in bilayer-graphene\n  double layers: We have fabricated bilayer-graphene double layers separated by a thin\n($\\sim$20 nm) boron nitride layer and performed Coulomb drag and counterflow\nthermoelectric transport measurements. The measured Coulomb drag resistivity is\nnearly three orders smaller in magnitude than the intralayer resistivities. The\ncounterflow Seebeck coefficient is found to be well approximated by the\ndifference between Seebeck coefficients of individual layers and exhibit a peak\nin the regime where two layers have opposite sign of charge carriers. The\nmeasured maximum counterflow power factor is $\\sim$ 700 $\\mu$W/K$^2$cm at room\ntemperature, promising high power output per mass for lightweight\nthermoelectric applications. Our devices open a possibility for exploring the\nnovel regime of thermoelectrics with tunable interactions between n-type and\np-type channels based on graphene and other two-dimensional materials and their\nheterostructures.",
        "positive": "Further improvement of lattice thermal conductivity from bulk\n  crystalline to 1-D-chain polyethylene: A high-yet-finite thermal conductivity\n  using first-principles calculation: We calculate the thermal conductivity (\\k{appa}) of both bulk crystalline and\nsingle-chain polyethylene (PE) using the first-principles-based anharmonic\nlattice dynamics. Despite its low \\k{appa} in amorphous state, the predicted\nbulk crystal has high axial \\k{appa} (237 W/m-K) at room temperature. The much\nlower measured \\k{appa} is attributed to the small size of nanocrystallites\n(~10 nm) in synthesized semi-crystalline PE. For the 1-D chain, the predicted\n\\k{appa} is much larger and yet finite (1400 W/m-K at room temperature). The\nreduction of scattering phase space caused by the diminished interchain van der\nWaals interactions explains this larger \\k{appa}. It is also found that the\ntransverse phonon branches with quadratic dispersion make minor contribution to\nthis, due to their vanishing group velocity in the long-wavelength limit.\nMoreover, the low-frequency bending and twisting phonon modes are strongly\ncoupled and dominate anharmonic phonon scatterings, leading to the finite\n\\k{appa}. The predicted high \\k{appa} of bulk and chain PE crystals enable\npolymer usage in thermal management and the above phonon scatterings provide\nguide for their nano-designs."
    },
    {
        "anchor": "Computing with Non-equilibrium Ratchets: Electronic ratchets transduce local spatial asymmetries into directed\ncurrents in the absence of a global drain bias, by rectifying temporal signals\nthat reside far from thermal equilibrium. We show that the absence of a drain\nbias can provide distinct energy advantages for computation, specifically,\nreducing static dissipation in a logic circuit. Since the ratchet functions as\na gate voltage-controlled current source, it also potentially reduces the\ndynamic dissipation associated with charging/discharging capacitors. In\naddition, the unique charging mechanism eliminates timing related constraints\non logic inputs, in principle allowing for adiabatic charging. We calculate the\nratchet currents in classical and quantum limits, and show how a sequence of\nratchets can be cascaded to realize universal Boolean logic.",
        "positive": "Self Excitation of Nano-Mechanical Pillars: Self excitation is a mechanism which is ubiquitous for electromechanical\npower devices such as electrical generators. This is conventionally achieved by\nmaking use of the magnetic field component in electrical generators [1], where\na good example are the overall visible wind farm turbines [2]. In other words,\na static force, like wind acting on the rotor blades, can generate a resonant\nexcitation at a certain mechanical frequency. For nanomechanical systems\n[3,4,5] such a self excitation (SE) mechanism is highly desirable as well,\nsince it can generate mechanical oscillations at radio frequencies by simply\napplying a DC bias voltage. This is of great importance for low-power signal\ncommunication devices and detectors, as well as for mechanical computing\nelements. For a particular nanomechanical system - the single electron shuttle\n- this effect was predicted some time ago by Gorelik et al. [6]. Here, we use a\nnano-electromechanical single electron transistor (NEMSET) to demonstrate self\nexcitation for both the soft and hard regime, respectively. The ability to use\nself excitation in nanomechanical systems may enable the detection of quantum\nmechanical backaction effects [7] in direct tunneling, macroscopic quantum\ntunneling [8], and rectification [9]. All these effects have so far been over\nshadowed by the large driving voltages, which had to be applied."
    },
    {
        "anchor": "Leaky interface phonons in AlGaAs/GaAs structures: A dispersion equation for the interface waves has been derived for the\ninterface of two cubic crystals in the plane perpendicular to [001]. A\nreasonable hypothesis has been made about the total number of the acoustic\nmodes. Due to this hypothesis the number is 64, but not all of the modes have\nphysical meaning of the interface waves. The rules have been worked out to\nselect physical branches among all 64 roots of dispersion equation. The\nphysical meaning of leaky interface waves is discussed. The calculations have\nbeen made for the interface Al$_{0.3}$Ga$_{0.7}$As/GaAs. In this case all\nphysical interface modes have been shown to be leaky. The velocities of the\ninterface waves are calculated as a function of an angle in the plane of\ninterface. The results support a recent interpretation of a new type\noscillations of magnetoresistance as a resonant scattering of two-dimensional\nelectron gas by the leaky interface phonons.",
        "positive": "Recent Advances in Studies of Current Noise: This is a brief review of recent activities in the field of current noise\nintended for newcomers. We first briefly discuss main properties of shot noise\nin nanostructures, and then turn to recent developments, concentrating on\nissues related to experimental progress: non-symmetrized cumulants and quantum\nnoise; counting statistics; super-Poissonian noise; current noise and\ninterferometry."
    },
    {
        "anchor": "Negative spin-Hall angle and anisotropic spin-orbit torques in epitaxial\n  IrMn: A spin-torque ferromagnetic resonance study is performed in epitaxial\n$\\mathrm{Fe / Ir_{15}Mn_{85}}$ bilayers with different Fe thicknesses. We\nmeasure a negative spin-Hall angle of a few percent in the antiferromagnetic\nIrMn in contrast to previously reported positive values. A large spin-orbit\nfield with Rashba symmetry opposing the Oersted field is also present.\nMagnitudes of measured spin-orbit torques depend on the crystallographic\ndirection of current and are correlated with the exchange bias direction set\nduring growth. We suggest that the uncompensated moments at the Fe / IrMn\ninterface are responsible for the observed anisotropy. Our findings highlight\nthe importance of crystalline and magnetic structures for the spin-Hall effect\nin antiferromagnets.",
        "positive": "Factors influencing the distribution of charge in polar nanocrystals: We perform first-principles calculations of wurtzite GaAs nanorods to explore\nthe factors determining charge distributions in polar nanostructures. We show\nthat both the direction and magnitude of the dipole moment $\\mathbf{d}$ of a\nnanorod, and its electic field, depend sensitively on how its surfaces are\nterminated and do not depend strongly on the spontaneous polarization of the\nunderlying lattice. We identify two physical mechanisms by which $\\mathbf{d}$\nis controlled by the surface termination, and we show that the excess charge on\nthe nanorod ends is not strongly localized. We discuss the implications of\nthese results for tuning nanocrystal properties, and for their growth and\nassembly."
    },
    {
        "anchor": "(Mis-)handling gauge invariance in the theory of the quantum Hall effect\n  I: Unifying action and the \u03bd=1/2 state: We propose a unifying theory for both the integral and fractional quantum\nHall regimes. This theory reconciles the Finkelstein approach to localization\nand interaction effects with the topological issues of an instanton vacuum and\nChern-Simons gauge theory. We elaborate on the microscopic origins of the\neffective action and unravel a new symmetry in the problem with Coulomb\ninteractions which we name F-invariance. This symmetry has a broad range of\nphysical consequences which will be the main topic of future analyses. In the\nsecond half of this paper we compute the response of the theory to\nelectromagnetic perturbations at a tree level approximation. This is applicable\nto the theory of ordinary metals as well as the composite fermion approach to\nthe half-integer effect. Fluctuations in the Chern-Simons gauge fields are\nfound to be well behaved only when the theory is F-invariant.",
        "positive": "Thermopower of Kondo Effect in Single Quantum Dot Systems with Orbital\n  at Finite Temperatures: We investigate the thermopower due to the orbital Kondo effect in a single\nquantum dot system by means of the noncrossing approximation. It is elucidated\nhow the asymmetry of tunneling resonance due to the orbital Kondo effect\naffects the thermopower under gate-voltage and magnetic-field control."
    },
    {
        "anchor": "Excitation of SPP's in graphene by a waveguide mode: We present a semi-analytical model that predicts the excitation of\nsurface-plasmon polaritons (SPP) on a graphene sheet located in front of a\nsub-wavelength slit drilled in thick metal screen. We identify the signature of\nthe SPP in the transmission, reflection, and absorption curves. Following\nprevious literature on noble-metal plasmonics, we characterize the efficiency\nof excitation of SPP's in graphene computing a spatial probability density.\nThis quantity shows the presence of plasmonics resonances dispersing with the\nFermi energy, $E_F$, as $\\sqrt{E_F}$ an unambiguous signature of graphene\nplasmons.",
        "positive": "Driven conductance of an irradiated semi-Dirac material: We theoretically investigate the electronic and transport properties of a\nsemi-Dirac material under the influence of an external time dependent periodic\ndriving field (irradiation) by means of Floquet theory. We explore the\ninelastic scattering mechanism between different side-bands, induced by\nirradiation, by using Floquet scattering matrix approach. The scattering\nprobabilities between two nearest side-bands depend monotonically on the\nstrength of the amplitude of the irradiation. The external irradiation induces\ngap into the band dispersion which is strongly dependent on the angular\norientation of momentum. Although, the high frequency limit indicates that the\ngap opening does not occur in an irradiated semi-Dirac material, a careful\nanalysis of the full band structure beyond this limit reveals that gap opening\nindeed appears for higher values of momentum (away from the Dirac point).\nFurthermore, the angular dependent dynamical gap is also present which cannot\nbe captured within the high frequency approximation. The contrasting features\nof irradiated semi-Dirac material, in comparison to irradiated graphene, can be\nprobed via the behavior of conductance. The latter exhibits the appearance of\nnon-zero conductance dips due to the gap opening in Floquet band spectrum.\nMoreover, by considering a nanoribbon geometry of such material, we also show\nthat it can host a pair of edge modes which are fully decoupled from the bulk,\nwhich is in contrast to the case of graphene nanoribbon where the edge modes\nare coupled to the bulk. We also investigate that if the nanoribbon of this\nmaterial is exposed to the external irradiation, decoupled edge modes penetrate\ninto the bulk."
    },
    {
        "anchor": "Strain-Modulated Graphene Heterostructure as a Valleytronic Current\n  Switch: Strain engineering is a promising approach for suppressing the OFF-state\nconductance in graphene-based devices that arises from Klein tunnelling. In\nthis work, we derive a comprehensive tight-binding Hamiltonian for strained\ngraphene that incorporates strain-induced effects that have been neglected\nhitherto, such as the distortion of the unit cell under strain, the effect of\nstrain on the next-nearest neighbor coupling, and the second-order\ncontributions of the strain tensor. We derive the corresponding low-energy\neffective Hamiltonian about the Dirac points and reformulate the boundary\nconditions at the interfaces between strained and unstrained graphene in light\nof additional terms in the Hamiltonian. By applying these boundary conditions,\nwe evaluate the transmission across a strained graphene heterostructure\nconsisting of a central segment sandwiched between two unstrained leads.\nModulation of the transmitted current can be effected by varying the magnitude\nand direction of the applied strain, as well as by the applying a gate voltage.\nBased on realistic parameter values, we predict that high ON-OFF ratios of up\nto $10^{12}$ as well as high current valley polarization can be achieved in the\nstrain-modulated device.",
        "positive": "Exotic states of matter with polariton chains: We consider linear periodic chains of exciton-polariton condensates formed by\npumping polaritons non-resonantly into a linear network. To the leading order,\nsuch a sequence of condensates establishes relative phases as to minimize a\nclassical one-dimensional XY Hamiltonian with nearest and next to nearest\nneighbors. We show that the low energy states of polaritonic linear chains\ndemonstrate various classical regimes: ferromagnetic, antiferromagnetic and\nfrustrated spiral phases, where quantum or thermal fluctuations are expected to\ngive rise to a spin liquid state. At the same time nonlinear interactions at\nhigher pumping intensities bring about phase chaos and novel exotic phases."
    },
    {
        "anchor": "Electronic Structure Shift of Deep Nanoscale Silicon by SiO$_2$- vs.\n  Si$_3$N$_4$-Embedding as Alternative to Impurity Doping: Conventional impurity doping of deep nanoscale silicon (dns-Si) used in ultra\nlarge scale integration (ULSI) faces serious challenges below the 14 nm\ntechnology node. We report on a new fundamental effect in theory and\nexperiment, namely the electronic structure of dns-Si experiencing energy\noffsets of ca. 1 eV as a function of SiO$_2$- vs. Si$_3$N$_4$-embedding with a\nfew monolayers (MLs). An interface charge transfer (ICT) from dns-Si specific\nto the anion type of the dielectric is at the core of this effect and arguably\nnested in quantum-chemical properties of oxygen (O) and nitrogen (N) vs. Si. We\ninvestigate the size up to which this energy offset defines the electronic\nstructure of dns-Si by density functional theory (DFT), considering interface\norientation, embedding layer thickness, and approximants featuring two Si\nnanocrystals (NCs); one embedded in SiO$_2$ and the other in Si$_3$N$_4$.\nWorking with synchrotron ultraviolet photoelectron spectroscopy (UPS), we use\nSiO$_2$- vs. Si$_3$N$_4$-embedded Si nanowells (NWells) to obtain their energy\nof the top valence band states. These results confirm our theoretical findings\nand gauge an analytic model for projecting maximum dns-Si sizes for NCs,\nnanowires (NWires) and NWells where the energy offset reaches full scale,\nyielding to a clear preference for electrons or holes as majority carriers in\ndns-Si. Our findings can replace impurity doping for n/p-type dns-Si as used in\nultra-low power electronics and ULSI, eliminating dopant-related issues such as\ninelastic carrier scattering, thermal ionization, clustering, out-diffusion and\ndefect generation. As far as majority carrier preference is concerned, the\nelimination of those issues effectively shifts the lower size limit of Si-based\nULSI devices to the crystalization limit of Si of ca. 1.5 nm and enables them\nto work also under cryogenic conditions.",
        "positive": "Edge State and Intrinsic Hole Doping in Bilayer Phosphorene: Using a simple LCAO model by Harrison, we have qualitatively studied the edge\nstate of bilayer phosphorene, which is a unit structure of the layered crystal\nof black phosphorus. This model successfully reproduces the isolated edge state\nin the bulk gap in monolayer phosphorene. In bilayer phosphorene, however, it\nshows that edge states are almost buried in the valence band and there is no\nisolated midgap edge state at the zigzag edge. Since the buried edge state\nworks as acceptor, holes are doped from the edge state into the bulk. This\ngives a possible explanation for p-type conduction in undoped black phosphorus.\nUnder the vertical electric field, the intrinsic hole doping is reduced because\na part of edge states move into the gap. These features of bilayer phosphorene\nmight be better suited for device application."
    },
    {
        "anchor": "Role of spin mixing conductance in determining thermal spin pumping near\n  the ferromagnetic phase transition in EuO_{1-x} and La2NiMnO6: We present a comprehensive study of the temperature (T) dependence of the\nlongitudinal spin Seebeck effect (LSSE) in Pt/EuO_{1-x} and Pt/La2NiMnO6 (LNMO)\nhybrid structures across their Curie temperatures (Tc). Both systems host\nferromagnetic interaction below Tc, hence present optimal conditions for\ntesting magnon spin current based theories against ferrimagnetic YIG. Notably,\nwe observe an anomalous Nernst effect (ANE) generated voltage in bare\nEuO_{1-x}, however, we find LSSE predominates the thermal signals in the\nbilayers with Pt. The T-dependence of the LSSE in small T-range near Tc could\nbe fitted to a power law of the form (Tc-T)^P. The derived critical exponent,\nP, was verified for different methods of LSSE representation and sample\ncrystallinity. The results are explained based on the magnon-driven thermal\nspin pumping mechanism that relate the T-dependence of LSSE to the spin mixing\nconductance (Gmix) at the heavy metal/ferromagnet (HM/FM) interface, which in\nturn is known to vary in accordance with the square of the spontaneous\nmagnetization (Ms). Additionally, the T-dependence of the real part of Gmix\nderived from spin Hall magnetoresistance measurements at different temperatures\nfor the Pt/LNMO structure, further establish the interdependence.",
        "positive": "Excited state spectroscopy and spin splitting in atomically thin quantum\n  dots: Semiconducting transition metal dichalcogenides (TMDCs) are very promising\nmaterials for quantum dots and spin-qubit implementation. Reliable operation of\nspin qubits requires the knowledge of Land\\'e g-factor, which can be measured\nby exploiting the discrete energy spectrum on a quantum dot. However, the\nquantum dots realized in TMDCs has yet to reach the required quality for\nreliable measurement of g-factor. Quantum dot sizes reported in TMDCs so far\nare not small enough to observe discrete energy levels on them. Here, we report\non electron transport through discrete energy levels of quantum dot in a single\nlayer MoS2. The quantum dot energy levels are separated by few (5-6) meV such\nthat the ground state and the excited state transitions are clearly visible.\nThis well resolved energy separation allows us to accurately measure the ground\nstate g-factor of ~5 in MoS2 quantum dots. We observe a spin filling sequence\nin our quantum dot under perpendicular magnetic field. Such a system offers an\nexcellent testbed to measure the key parameters for evaluation and\nimplementation of spin-valley qubits in TMDCs, thus accelerating the\ndevelopment of quantum systems in two dimensional semiconducting TMDCs."
    },
    {
        "anchor": "Bandstructure Effects in Multiwall Carbon Nanotubes: We report conductance measurements on multiwall carbon nanotubes in a\nperpendicular magnetic field. A gate electrode with large capacitance is used\nto considerably vary the nanotube Fermi level. This enables us to search for\nsignatures of the unique electronic band structure of the nanotubes in the\nregime of diffusive quantum transport. We find an unusual quenching of the\nmagnetoconductance and the zero bias anomaly in the differential conductance at\ncertain gate voltages, which can be linked to the onset of\nquasi-one-dimensional subbands.",
        "positive": "Symmetries of quantum transport with Rashba spin-orbit: Graphene\n  spintronics: The lack of some spatial symmetries in planar devices with Rashba spin-orbit\ninteraction opens the possibility of producing spin polarized electrical\ncurrents in absence of external magnetic field or magnetic impurities. We study\nhow the direction of the spin polarization of the current is related to spatial\nsymmetries of the device. As an example of these relations we study numerically\nthe spin-resolved current in graphene nanoribbons. Different configurations are\nexplored and analyzed to demonstrate that graphene nanoflakes may be used as\nexcellent spintronic devices in an all-electrical setup."
    },
    {
        "anchor": "Nonlinear Optical studies of the Transient Coherence in the Quantum Hall\n  System: We review recent investigations of the femtosecond non-linear optical\nresponse of the two-dimensional electron gas (2DEG) in a strong magnetic field.\nWe probe the Quantum Hall (QH) regime for filling factors $\\nu \\sim 1$. Our\nfocus is on the transient coherence induced via optical excitation and on its\ntime evolution during early femtosecond timescales. We simultaneously study the\ninterband and intraband coherence in this system by using a nonlinear\nspectroscopic technique, transient three-pulse four wave mixing optical\nspectroscopy, and a many-body theory. We observe striking differences in the\ntemporal and spectral profile of the nonlinear optical signal between a\nmodulation doped quantum well system (with the 2DEG) and a similar undoped\nquantum well (without a 2DEG). We attribute these qualitative differences to\nCoulomb correlations between the photoexcited electron-hole pairs and the 2DEG.\nWe show, in particular, that intraband many-particle coherences assisted by the\ninter-Landau-level magnetoplasmon excitations of the 2DEG dominate the\nfemtosecond nonlinear optical responce. The most striking effect of these\nexciton-magnetoplasmon coherences is a large off-resonant four-wave-mixing\nsignal in the case of very low photoexcited carrier densities, not observed in\nthe undoped system, with strong temporal oscillations and unusually symmetric\ntemporal profile.",
        "positive": "Theory of Interfacial Plasmon-Phonon Scattering in Supported Graphene: One of the factors limiting electron mobility in supported graphene is remote\nphonon scattering. We formulate the theory of the coupling between graphene\nplasmon and substrate surface polar phonon (SPP) modes, and find that it leads\nto the formation of interfacial plasmon-phonon (IPP) modes, from which the\nphenomena of dynamic anti-screening and screening of remote phonons emerge. The\nremote phonon-limited mobilities for SiO$_{2}$, HfO$_{2}$, h-BN and\nAl$_{2}$O$_{3}$ substrates are computed using our theory. We find that h-BN\nyields the highest peak mobility, but in the practically useful high-density\nrange the mobility in HfO$_{2}$-supported graphene is high, despite the fact\nthat HfO$_{2}$ is a high-$\\kappa$ dielectric with low-frequency modes. Our\ntheory predicts that the strong temperature dependence of the total mobility\neffectively vanishes at very high carrier concentrations. The effects of\npolycrystallinity on IPP scattering are also discussed."
    },
    {
        "anchor": "Collision of nanoparticles of covalently bound atoms. Impact of\n  stress-dependent adhesion: The impact of nanoparticles (NPs) comprised of atoms with covalent bonding is\ninvestigated numerically and theoretically. We use recent models of covalent\nbonding of carbon atoms and elaborate a numerical model of amorphous carbon\n(a-C) NPs, which may be applied for modelling soot particles. We compute the\nelastic moduli of the a-C material which agree well with the available data. We\nreveal an interesting novel phenomenon - stress dependent adhesion, which\nrefers to stress-enhanced formation of covalent bonds between contacting\nsurfaces. We observe that the effective adhesion coefficient linearly depends\non the maximal stress between the surfaces and explain this dependence. We\ncompute the normal restitution coefficient for colliding NPs and explore the\ndependence of the critical velocity, demarcating bouncing and aggregative\ncollisions, on the NP radius. Using the obtained elastic and stress-dependent\nadhesive coefficients we develop a theory for the critical velocity. The\npredictions of the theory agree very well with the simulation results.",
        "positive": "Protected Weyl semimetals within 2D chiral classes: Weyl semimetals in three dimensions can exist independently of any symmetry\napart from translations. Conversely, in two dimensions, Weyl semimetals are\nbelieved to require additional symmetries including crystalline symmetries to\nexist. In this study, we demonstrate that a 2D Weyl semimetal phase can exist\nin systems with Hamiltonians possessing internal symmetries, such as time\nreversal ${\\cal T}$, charge conjugation ${\\cal C}$ , and their combined chiral\nsymmetry ${\\cal S} = {\\cal CT}$, only. Starting from a minimal-dimension Dirac\nHamiltonian, we establish the presence of a stable Weyl semimetal phase in each\nof the five chiral classes: AIII, BDI, CII, DIII, and CI in two dimension.\nSimilar to 3D Weyl semimetals where Weyl points possess nontrivial topological\ncharges (Chern number), the Weyl points in WSMs within the 2D chiral classes\nare characterized by the $Z$ winding numbers. In accordance with the\nbulk-boundary correspondence, protected Fermi arc edge states emerge,\nconnecting the projections of Weyl points that carry opposite topological\ncharges. Unlike the surface states in 3D WSMs, the edge states of WSMs within\n2D chiral classes are completely dispersionless and are always at the zero\nenergy due to the protecting chiral symmetry."
    },
    {
        "anchor": "Role of transparency of platinum-ferromagnet interface in determining\n  intrinsic magnitude of spin Hall effect: The spin Hall effect (SHE) converts charge current to pure spin currents in\northogonal directions in materials that have significant spin-orbit\ncoupling.The efficiency of the conversion is described by the spin Hall Angle\n(SHA). The SHA can most readily be inferred by using the generated spin\ncurrents to excite or rotate the magnetization of ferromagnetic films or\nnano-elements via spin-transfer torques.Some of the largest spin torque derived\nspin Hall angles (ST-SHA) have been reported in platinum. Here we show, using\nspin torque ferromagnetic resonance (ST-FMR) measurements, that the\ntransparency of the Pt-ferromagnet interface to the spin current plays a\ncentral role in determining the magnitude of the ST-SHA. We measure a much\nlarger ST-SHA in Pt/cobalt (~0.11) compared to Pt/permalloy (~0.05) bilayers\nwhen the interfaces are assumed to be completely transparent. Taking into\naccount the transparency of these interfaces, as derived from spin-mixing\nconductances, we find that the intrinsic SHA in platinum has a much higher\nvalue of 0.19 +- 0.04 as compared to the ST-SHA. The importance of the\ninterface transparency is further exemplified by the insertion of atomically\nthin magnetic layers at the Pt/permalloy interface that we show strongly\nmodulates the magnitude of the ST-SHA.",
        "positive": "Generalized Dynamic Junction Theory to Resolve the Mechanism of Direct\n  Current Generation in Liquid-Solid Interfaces: Despite the unsettled mechanism of electricity generation from the continuous\nflow of liquids on a surface, the charge-discharge theory has been widely\naccepted for alternating current (AC) generation from a moving droplet. It has\nbeen recently extended to rationalize direct current (DC) generation across a\ndroplet moving between two different materials. By designing a reconfigurable\ncontact between a metal wire and a water droplet moving on graphene, we show\nthat the charge-discharge theory cannot explain the reversal of current when\nwater-metal interfaces switch from dynamic to static. All experiments can be\ndescribed after we distinguish a dynamic from a static interface and generalize\nthe photovoltaic-like effect to all dynamic junctions: excited electrons and\nholes in a moving interface will be separated and swept under the built-in\nelectrical field, leading to a DC response. This generalized theory will lead\nto an understanding and the design of efficient electricity generation based on\ninterfacial charge transfer."
    },
    {
        "anchor": "Piezoelectric networks and ferroelectric moir\u00e9 superlattice domains in\n  twistronic WS$_2$/MoS$_2$ and WSe$_2$/MoSe$_2$ bilayers: Twistronic van der Waals heterostrutures offer exciting opportunities for\nengineering optoelectronic properties of nanomaterials. Here, we use multiscale\nmodeling to study trapping of charge carriers and excitons by ferroelectric\npolarisation and piezoelectric charges by domain structures in twistronic\nWX$_2$/MoX$_2$ bilayers (X=S,Se). For almost aligned 2H-type bilayers, we find\nthat holes and electrons are trapped in the opposite -- WMo and XX (tungsten\nover molybdenum {\\it versus} overlaying chalcogens) -- corners of the honeycomb\ndomain wall network, swapping their position at a twist angle $0.2^{\\circ}$,\nwith XX corners providing $30$\\,meV deep traps for the interlayer excitons for\nall angles. In 3R-type bilayers, both electrons and holes are trapped in\ntriangular \"3R stacking\" domains, where WX$_2$ chalcogens set over MoX$_2$\nmolybdenums, which act as $130$\\,meV deep quantum boxes for interlayer excitons\nfor twist angles $\\lesssim 1^{\\circ}$, for larger angles shifting towards\ndomain wall network XX stacking sites.",
        "positive": "Experimental observation of an enhanced anisotropic magnetoresistance in\n  non-local configuration: We compare non-local magnetoresistance measurements in multi-terminal Ni\nnanostructures with corresponding local experiments. In both configurations,\nthe measured voltages show the characteristic features of anisotropic\nmagnetoresistance (AMR). However, the magnitude of the non-local AMR signal is\nup to one order of magnitude larger than its local counterpart. Moreover, the\nnon-local AMR increases with increasing degree of non-locality, i.e., with the\nseparation between the region of the main current flow and the voltage\nmeasurement region. All experimental observations can be consistently modeled\nin terms of current spreading in a non-isotropic conductor. Our results show\nthat current spreading can significantly enhance the magnetoresistance signal\nin non-local experiments."
    },
    {
        "anchor": "Spin-dependent edge-channel transport in a Si/SiGe quantum Hall system: We study the edge-channel transport of electrons in a high-mobility Si/SiGe\ntwo-dimensional electron system in the quantum Hall regime. By selectively\npopulating the spin-resolved edge channels, we observe suppression of the\nscattering between two edge channels with spin-up and spin-down. In contrast,\nwhen the Zeeman splitting of the spin-resolved levels is enlarged with tilting\nmagnetic field direction, the spin orientations of both the relevant edge\nchannels are switched to spin-down, and the inter-edge-channel scattering is\nstrongly promoted. The evident spin dependence of the adiabatic edge-channel\ntransport is an individual feature in silicon-based two-dimensional electron\nsystems, originating from a weak spin-orbit interaction.",
        "positive": "Dirac electronic states in graphene systems: Optical spectroscopy\n  studies: Electronic properties of two-dimensional allotropes of carbon, such as\ngraphene and its bilayer, multi-layer epitaxial graphene, few-layer\nBernal-stacked graphene, as well as of three-dimensional bulk graphite are\nreviewed from the viewpoint of recent optical spectroscopy studies. Attention\nis focused on relativistic-like character of quasi particles in these systems,\nwhich are referred to as massless or massive Dirac fermions."
    },
    {
        "anchor": "Spin-Dependent Coulomb Blockade in Ferromagnet/Normal-Metal/Ferromagnet\n  Double Tunnel Junctions: We study theoretically the spin-dependent transport in\nferromagnet/normal-metal/ferromagnet double tunnel junctions by special\nattention to cotunneling in the Coulomb blockade region. The spin accumulation\ncaused by cotunneling squeezes the Coulomb blockade region when the\nmagnetizations in the ferromagnetic electrodes are antiparallel. Outside the\nsqueezed Coulomb blockade region, we propose a new anomalous region, where the\nsequential tunneling in one of the spin bands is suppressed by the Coulomb\nblockade and that in the other is not. In this region, the tunnel\nmagnetoresistance oscillates as a function of bias voltage. The temperature\ndependences of the tunnel magnetoresistance and the magnitude of the spin\naccumulation are calculated.",
        "positive": "Origin of magnetic switching cascades in tetrahedral CoFe nanostructures: We present a comprehensive study of small-scale three-dimensional (3D)\ntetrahedral CoFe nanostructure arrays prepared by focused electron beam-induced\ndeposition (FEBID) and placed in two distinct orientations with respect to the\ndirection of an external magnetic field. Using ultra-sensitive micro-Hall\nmagnetometry we obtain angular-dependent magnetic stray field hysteresis loops\nthat show characteristic cascading magnetic switching close to zero magnetic\nfield. By employing micromagnetic simulations we could reproduce the hysteresis\nloops and identify characteristic field dependent magnetic configurations\nincluding a vortex-type groundstate. From this we derive a coarse-graining\nmacrospin model and show that the complex switching behavior can be explained\nby the reorientation dynamics of non-interacting uniaxial anisotropic magnetic\ngrains modeled as a superposition of Stoner-Wohlfarth particles."
    },
    {
        "anchor": "Using light and heat to controllably switch and reset disorder\n  configuration in nanoscale devices: Quantum dots exhibit reproducible conductance fluctuations at low\ntemperatures due to electron quantum interference. The sensitivity of these\nfluctuations to the underlying disorder potential has only recently been fully\nrealized. We exploit this sensitivity to obtain a novel tool for better\nunderstanding the role that background impurities play in the electrical\nproperties of high-mobility AlGaAs/GaAs heterostructures and nanoscale devices.\nIn particular, we report the remarkable ability to first alter the disorder\npotential in an undoped AlGaAs/GaAs heterostructure by optical illumination and\nthen reset it back to its initial configuration by room temperature thermal\ncycling in the dark. We attribute this behavior to a mixture of C background\nimpurities acting as shallow acceptors and deep trapping by Si impurities. This\n\"alter and reset\" capability, not possible in modulation-doped\nheterostructures, offers an exciting route to studying how scattering from even\nsmall densities of charged impurities influences the properties of nanoscale\nsemiconductor devices.",
        "positive": "Fano resonance in a two-level quantum dot side-coupled to leads: We theoretically study Fano resonance in a two-level quantum dot side-coupled\nto two leads, which are connected by a direct channel. The resonance lineshape\nis found to be deformed, from the conventional Fano form, by interlevel Coulomb\ninteraction and interlevel interference. We derive the connection between the\nlineshape deformation and the interaction-induced nonmonotonicity of level\noccupation, which may be useful for experimental study. The dependence of the\nlineshape on the transmission of the direct channel and on the dot-lead\ncoupling matrix elements is discussed."
    },
    {
        "anchor": "Strong Room-Temperature Bulk Nonlinear Hall Effect in a Spin-Valley\n  Locked Dirac Material: Nonlinear Hall effect (NLHE) is a new type of Hall effect with wide\napplication prospects. Practical device applications require strong NLHE at\nroom temperature (RT). However, previously reported NLHEs are all\nlow-temperature phenomena except for the surface NLHE of TaIrTe4. Bulk RT NLHE\nis highly desired due to its ability to generate large photocurrent. Here, we\nshow the spin-valley locked Dirac state in BaMnSb2 can generate a strong bulk\nNLHE at RT. In the microscale devices, we observe the typical signature of an\nintrinsic NLHE, i.e. the transverse Hall voltage quadratically scales with the\nlongitudinal current as the current is applied to the Berry curvature dipole\ndirection. Furthermore, we also demonstrate our nonlinear Hall device's\nfunctionality in wireless microwave detection and frequency doubling. These\nfindings broaden the coupled spin and valley physics from 2D systems into a 3D\nsystem and lay a foundation for exploring bulk NLHE's applications.",
        "positive": "Landau level spin diode in a GaAs two dimensional hole system: We have fabricated and characterized the Landau level spin diode in GaAs two\ndimensional hole system. We used the hole Landau level spin diode to probe the\nhyperfine coupling between the hole and nuclear spins and found no detectable\nnet nuclear polarization, indicating that hole-nuclear spin flip-flop processes\nare suppressed by at least three orders of magnitude compared to GaAs electron\nsystems."
    },
    {
        "anchor": "Probing Spin-Charge Separation in Tunnel-Coupled Parallel Quantum Wires: Interactions in one-dimensional (1D) electron systems are expected to cause a\ndynamical separation of electronic spin and charge degrees of freedom. A\npromising system for experimental observation of this non-Fermi-liquid effect\nconsists of two quantum wires coupled via tunneling through an extended uniform\nbarrier. Here we consider the minimal model of an interacting 1D electron\nsystem exhibiting spin-charge separation and calculate the differential\ntunneling conductance as well as the density-density response function. Both\nquantities exhibit distinct strong features arising from spin-charge\nseparation. Our analysis of these features within the minimal model neglects\ninteractions between electrons of opposite chirality and applies therefore\ndirectly to chiral 1D electron systems realized, e.g., at the edge of integer\nquantum-Hall systems. Physical insight gained from our results is useful for\ninterpreting current experiment in quantum wires as our main conclusions still\napply with nonchiral interactions present. In particular, we discuss the effect\nof charging due to applied voltages, and the possibility to observe spin-charge\nseparation in a time-resolved experiment.",
        "positive": "Clean ballistic quantum point contact in SrTiO$_3$: Two dimensional electron gases based on SrTiO$_3$ are an intriguing platform\nfor exploring mesoscopic superconductivity combined with spin-orbit coupling,\noffering electrostatic tunability from insulator to metal to superconductor\nwithin a single material. So far, however, quantum effects in SrTiO$_3$\nnanostructures have been complicated by disorder. Here we introduce a facile\napproach to achieving high mobility and patterning gate-tunable structures in\nSrTiO$_3$, and use it to demonstrate ballistic constrictions with clean normal\nstate conductance quantization. Conductance plateaus show two-fold degeneracy\nthat persists to magnetic fields of at least 5 T - far beyond what one would\nexpect from the $g$-factor extracted at high fields - a potential signature of\nelectron pairing extending outside the superconducting regime."
    },
    {
        "anchor": "Theory of qubit noise characterization using the long-time cavity\n  transmission: Noise induced decoherence is one of the main threats to large-scale quantum\ncomputation. In an attempt to assess the noise affecting a qubit we go beyond\nthe standard steady-state solution of the transmission through a qubit-coupled\ncavity in input-output theory by including dynamical noise in the description\nof the system. We solve the quantum Langevin equations exactly for a noise-free\nsystem and treat the noise as a perturbation. In the long-time limit the\ncorrections may be written as a sum of convolutions of the noise power spectral\ndensity with an integration kernel that depends on external control parameters.\nUsing the convolution theorem, we invert the corrections and obtain relations\nfor the noise spectral density as an integral over measurable quantities.\nAdditionally, we treat the noise exactly in the dispersive regime, and again\nfind that noise characteristics are imprinted in the long-time transmission in\nconvolutions containing the power spectral density.",
        "positive": "Scanning Tunneling Microscopy and Spectroscopy study of charge\n  inhomogeneities in bilayer Graphene: We report room temperature scanning tunneling microscopy and spectroscopy\nstudy of bilayer graphene prepared by mechanical exfoliation on SiO$_2$/Si\nsurface and electrically contacted with gold pads using a mechanical mask. The\nbulk conductivity shows contribution from regions of varying electron density\nindicating significant charge inhomogeneity. Large scale topographic images\nshow ripple like structures with a roughness of $\\sim$1nm while the small scale\natomic resolution images show graphite-like triangular lattice. Local dI/dV-V\ntunnel spectra have an asymmetric V-shape with the minima location showing\nsignificant spatial variation indicating inhomogeneity in electron density of\norder 10$^{11}$ cm-2. The minima in spectra at a fixed location also shifts\nlinearly with the gate voltage with a slope consistent with the field induced\ncarrier density."
    },
    {
        "anchor": "Relative Phase and Josephson Dynamics between Weakly Coupled Richardson\n  Models: We consider two weakly coupled Richardson models to study the formation of a\nrelative phase and the Josephson dynamics between two mesoscopic attractively\ninteracting fermionic systems: our results apply to superconducting properties\nof coupled ultrasmall metallic grains and to Cooper-pairing superfluidity in\nneutral systems with a finite number of fermions. We discuss how a definite\nrelative phase between the two systems emerges and how it can be conveniently\nextracted from the many-body wavefunction: we find that a definite relative\nphase difference emerges even for very small numbers of pairs ~10. The\nJosephson dynamics and the current-phase characteristics are then investigated,\nshowing that the critical current has a maximum at the BCS-BEC crossover. For\nthe considered initial conditions a two-state model gives a good description of\nthe dynamics and of the current-phase characteristics.",
        "positive": "Probing the magnetic moment of FePt micromagnets prepared by Focused Ion\n  Beam milling: We investigate the degradation of the magnetic moment of a 300 nm thick FePt\nfilm induced by Focused Ion Beam (FIB) milling. A $1~\\mu \\mathrm{m} \\times\n8~\\mu \\mathrm{m}$ rod is milled out of a film by a FIB process and is attached\nto a cantilever by electron beam induced deposition. Its magnetic moment is\ndetermined by frequency-shift cantilever magnetometry. We find that the\nmagnetic moment of the rod is $\\mu = 1.1 \\pm 0.1 \\times 10 ^{-12}\n\\mathrm{Am}^2$, which implies that 70% of the magnetic moment is preserved\nduring the FIB milling process. This result has important implications for atom\ntrapping and magnetic resonance force microscopy (MRFM), that are addressed in\nthis paper."
    },
    {
        "anchor": "Semiclassical theory of the interaction correction to the conductance of\n  antidot arrays: Electron-electron interactions are responsible for a correction to the\nconductance of a diffusive metal, the \"Altshuler-Aronov correction\" $\\delta\nG_{AA}$. Here we study the counterpart of this correction for a ballistic\nconductor, in which the electron motion is governed by chaotic classical\ndynamics. In the ballistic conductance, the Ehrenfest time $\\tau_{E}$ enters as\nan additional time scale that determines the magnitude of quantum interference\neffects. The Ehrenfest time effectively poses a short-time threshold for the\ntrajectories contributing to the interaction correction. As a consequence,\n$\\delta G_{AA}$ becomes exponentially suppressed if the Ehrenfest time is\nlarger than the dwell time or the inverse temperature. We discuss the explicit\ndependence on Ehrenfest time in quasi-one and two-dimensional antidot arrays.\nFor strong interactions, the sign of $\\delta G_{AA}$ may change as a function\nof temperature for temperatures in the vicinity of $\\hbar/\\tau_{E}$.",
        "positive": "Optimal thermoelectric figure of merit of a molecular junction: We show that a molecular junction can give large values of the thermoelectric\nfigure of merit $ZT$, and so could be used as a solid state energy conversion\ndevice that operates close to the Carnot efficiency. The mechanism is similar\nto the Mahan-Sofo model for bulk thermoelectrics -- the Lorenz number goes to\nzero violating the Wiedemann-Franz law while the thermopower remains non-zero.\nThe molecular state through which charge is transported must be weakly coupled\nto the leads, and the energy level of the state must be of order $k_B T$ away\nfrom the Fermi energy of the leads. In practice, the figure of merit is limited\nby the phonon thermal conductance; we show that the largest possible\n$ZT\\sim(\\tilde{G}_{th}^{ph})^{-1/2}$, where $\\tilde{G}_{th}^{ph}$ is the phonon\nthermal conductance divided by the thermal conductance quantum."
    },
    {
        "anchor": "GiftBTE: An efficient deterministic solver for non-gray phonon Boltzmann\n  transport equation: Advances in nanotechnology have facilitated the exploration of submicron\nthermal transport. At this scale, Fourier's law is no longer applicable, and\nthe governing equation for thermal transport is the phonon Boltzmann transport\nequation (BTE). However, the availability of open-source solvers for the phonon\nBTE is limited, impeding progress in this field. This study introduces an\nopen-source package, GiftBTE, for numerically solving the non-gray phonon BTE.\nGiftBTE employs deterministic solutions and provides both steady-state and\ntransient solvers. For the steady-state solver, GiftBTE employs the implicit\ndiscrete ordinates method (DOM) with second-order spatial accuracy and the\nsynthetic iterative scheme. For the transient solver, GiftBTE employs the\nexplicit DOM with second-order spatial accuracy. This package demonstrates\nexcellent computational efficiency, enabling realistic three-dimensional\nsimulations of devices and materials. By interfacing with first-principles\ncalculations, this solver enables parameter-free computation of submicron\nthermal transport. The application of GiftBTE includes, but is not limited to,\ncomputing the thermal conductivity of nanostructures, predicting temperature\nrises in transistors, and simulating laser heating processes.",
        "positive": "Emergence of Tertiary Dirac Points in Graphene Moir\u00e9 Superlattices: The electronic structure of a crystalline solid is largely determined by its\nlattice structure. Recent advances in van der Waals solids, artificial crystals\nwith controlled stacking of two-dimensional (2D) atomic films, have enabled the\ncreation of materials with novel electronic structures. In particular, stacking\ngraphene on hexagonal boron nitride (hBN) introduces moir\\'e superlattice that\nfundamentally modifies graphene's band structure and gives rise to secondary\nDirac points (SDPs). Here we find that the formation of a moir\\'e superlattice\nin graphene on hBN yields new, unexpected consequences: a set of tertiary Dirac\npoints (TDPs) emerge, which give rise to additional sets of Landau levels when\nthe sample is subjected to an external magnetic field. Our observations hint at\nthe formation of a hidden Kekul\\'e superstructure on top of the moir\\'e\nsuperlattice under appropriate carrier doping and magnetic fields."
    },
    {
        "anchor": "Nuclear Tuning and Detuning of the Electron Spin Resonance in a Quantum\n  Dot: We study nuclear spin dynamics in a quantum dot close to the conditions of\nelectron spin resonance. We show that at small frequency mismatch the nuclear\nfield detunes the resonance. Remarkably, at larger frequency mismatch its\neffect is opposite: The nuclear system is bistable, and in one of the stable\nstates the field accurately tunes the electron spin splitting to resonance. In\nthis state the nuclear field fluctuations are strongly suppressed and nuclear\nspin relaxation is accelerated.",
        "positive": "Local heating variations and transient effects in the coupling of\n  thermal radiation and non-Fourier heat transport: In this work, we study the thermalization between two bodies separated by a\nvacuum gap by coupling the non-Fourier behavior of the materials with the\nradiative heat transfer in the near-field. Unlike the diffusion-type\ntemperature profile, in non-Fourier materials, the temperature behaves as a\nwave, changing the thermalization process. Due to the temperature profile\ninduced by the coupling with conduction, we show that the radiative heat flux\nexchanged between the two bodies differs from the Fourier case, and exhibits\ntransient temperature effects at the onset of the thermalization process. These\nresults have important implications in nanoscale thermal management, near-field\nsolid-state cooling, and nanoscale energy conversion."
    },
    {
        "anchor": "Spin orbit interaction in nanotubes: In recent years, silicene, germanene, and stanene have received considerable\nattention due to their possibilities to show a spin Hall effect. Nanoribbons\nmade of these materials are expected to have topologically protected states.\n  In this work, we study the electronic properties of nanotubes made of Si, Ge,\nSn, and functionalized Sn. The main difference between these materials and\ngraphene is the relevance of spin-orbit interaction. The lack of edge states in\na seamless tube eliminates the possibility to find a topological edge state.\nThe spin-orbit interaction breaks the degeneracy of Dirac's cones and\neliminates the chances of finding a metal nanotube. As a consequence, this\ntransforms all nanotubes with spin-orbit interaction in trivial band\ninsulators.\n  We focus our attention on two features. First, we study the energy band gap\nas a function of the diameter of the nanotubes. Then, we concentrate on\ncontrolling the band gap of a nanotube by applying an external radial electric\nfield.",
        "positive": "Topological spin waves in the atomic-scale magnetic skyrmion crystal: We study the spin waves of the triangular skyrmion crystal that emerges in a\ntwo dimensional spin lattice model as a result of the competition between\nHeisenberg exchange, Dzyalonshinkii-Moriya interactions, Zeeman coupling and\nuniaxial anisotropy. The calculated spin wave bands have a finite Berry\ncurvature that, in some cases, leads to non-zero Chern numbers, making this\nsystem topologically distinct from conventional magnonic systems. We compute\nthe edge spin-waves, expected from the bulk-boundary correspondence principle,\nand show that they are chiral, which makes them immune to elastic\nbackscattering. Our results illustrate how topological phases can occur in\nself-generated emergent superlattices at the mesoscale."
    },
    {
        "anchor": "Ultra-Fast All-Electrical Universal Nano-Qubits: We propose how to create, control, and read-out real-space localized spin\nqubits in proximitized finite graphene nanoribbon (GNR) systems using purely\nelectrical methods. Our proposed nano-qubits are formed of in-gap\nsinglet-triplet states that emerge through the interplay of Coulomb and\nrelativistic spin-dependent interactions in GNRs placed on a magnetic\nsubstrate. Application of an electric field perpendicular to the GNR\nheterostructure leads to a sudden change in the proximity couplings, i.e. a\nquantum quench, which enables us to deterministically rotate the nano-qubit to\nany arbitrary point on the Bloch sphere. We predict these spin qubits to\nundergo Rabi oscillations with optimal visibility and frequencies in excess of\n10 GHz. Our findings open up a new avenue for the realization of graphene-based\nquantum computing with ultra-fast all-electrical methods.",
        "positive": "A Model for the Optical Absorption in Pororus Silicon: In this paper, we report on the optical absorption in porous silicon. We\nmodel the absorption process assuming that porous silicon is a pseudo 1D\nmaterial system having a distribution of band gaps. We show that in order to\nexplain the absorption we specifically need to invoke - (a) k is not conserved\nin optical transitions, (b) the oscillator strength of these transitions\ndepends on the size of the nanostructure in which absorption takes place and\n(c) the distribution of band gaps significantly influences the optical\nabsorption. We also show that it is not possible to extract the band gap of\nporous silicon from a plot of $\\sqrt{\\alpha\\hbar\\omega}$ vs $\\hbar\\omega$."
    },
    {
        "anchor": "Spin transport in fully hexagonal boron nitride encapsulated graphene: We study fully hexagonal boron nitride (hBN)-encapsulated graphene spin valve\ndevices at room temperature. The device consists of a graphene channel\nencapsulated between two crystalline hBN flakes; thick-hBN flake as a bottom\ngate dielectric substrate which masks the charge impurities from SiO2/Si\nsubstrate and single-layer thin-hBN flake as a tunnel barrier. Full\nencapsulation prevents the graphene from coming in contact with any\npolymer/chemical during the lithography and thus gives homogeneous charge and\nspin transport properties across different regions of the encapsulated\ngraphene. Further, even with the multiple electrodes in between the injection\nand the detection electrodes which are in conductivity mismatch regime, we\nobserve spin transport over 12.5 um long distance under the thin-hBN\nencapsulated graphene channel, demonstrating the clean interface and the\npin-hole free nature of the thin-hBN as an efficient tunnel barrier.",
        "positive": "Spin-1 Dirac half-metal, spin-gapless semiconductor, and spin-polarized\n  massive Dirac dispersion in transition metal dihalide monolayers: Spin-1 condensed matter systems characterized by the combination of a\nDirac-like dispersion and flat bands are ideal for realizing high-temperature\nelectronics and spintronic technologies in the absence of external magnetic\nfield. In this study, we propose a three-band tight binding model, with\nspin-polarized Haldane-like next-nearest-neighbour tunnelling, on dice lattice\nand show that spin-1 Dirac half-metal, spin-1 Dirac spin-gapless semiconductor,\nand spin-polarized spin-1 massive Dirac dispersion with nontrivial topology can\nexist in two-dimensional ferromagnetic condensed matter systems with electron\nspin polarization P = 1. The proposed spin-polarized spin-1 phases can be\nrealized in ferromagnetic transition metal dihalides MX2 monolayers\neffectively. By using first principle calculations, we show that a small\ncompressive strain leads MX2 monolayers to be spin-one Dirac half-metal for M =\nFe and X = Br, Cl while spin-one Dirac spin-gapless semiconductor for M = Co\nand X = Br, Cl. Spin-one Dirac spin-gapless semiconductors CoBr2 and CoCl2\nembeds flat band ferromagnetism where spin-orbit coupling opens a topologically\nnon-trivial Dirac gap between dispersing valance and conduction band while\nleaving flat band unaffected. The intrinsic flat-band ferromagnetism in\nspin-polarized spin-1 massive Dirac dispersion plays key role in materializing\nquantum anomalous Hall state with Chern number C = -2."
    },
    {
        "anchor": "Quantum Computing with Majorana Kramers Pairs: We propose a universal gate set acting on a qubit formed by the degenerate\nground states of a Coulomb-blockaded time-reversal invariant topological\nsuperconductor island with spatially separated Majorana Kramers pairs: the\n\"Majorana Kramers Qubit\". All gate operations are implemented by coupling the\nMajorana Kramers pairs to conventional superconducting leads. Interestingly, in\nsuch an all-superconducting device, the energy gap of the leads provides\nanother layer of protection from quasiparticle poisoning independent of the\nisland charging energy. Moreover, the absence of strong magnetic fields - which\ntypically reduce the superconducting gap size of the island - suggests a unique\nrobustness of our qubit to quasiparticle poisoning due to thermal excitations.\nConsequently, the Majorana Kramers Qubit should benefit from prolonged\ncoherence times and may provide an alternative route to a Majorana-based\nquantum computer.",
        "positive": "Impact of gate leakage considerations in tunnel field effect transistor\n  design: In this paper, we have presented the impact of the gate leakage through thin\ngate dielectrics (SiO2 and high-\\k{appa} gate dielectric) on the subthreshold\ncharacteristics of the tunnel field effect transistors (TFET) for a low\noperating voltage of 0.5 V. Using calibrated two-dimensional simulations it is\nshown that even for such a low operating voltage, the gate leakage\nsubstantially degrades several subthreshold parameters of the TFET such as the\noff-state current, minimum subthreshold swing and average subthreshold swing.\nWhile the drain-offset as well as the short-gate are effective methods for\nreducing the gate leakage, we show that if the gate tunneling leakage is not\nconsidered, even for these two methods, the overall TFET off-state current will\nbe significantly underestimated. Our results demonstrate the need to carefully\naccount for the gate leakage in the design of TFETs just as it is done for the\nconventional nanoscale MOSFETs."
    },
    {
        "anchor": "Shaping magnetization dynamics in a planar square dot by adjusting its\n  surface anisotropy: A planar square dot is one of the simplest structures confined to three\ndimensions. Despite its geometrical simplicity, the description of the spin\nwave modes in this structure is not trivial due to the competition of dipolar\nand exchange interactions. An additional factor that makes this description\nchallenging are the boundary conditions depend both on non-local dipolar\ninteractions and local surface parameters such as surface anisotropy. In the\npresented work, we showed how the surface anisotropy applied at the lateral\nfaces of the dot can tune the frequency of fundamental mode in the planar CoFeB\ndot, magnetized in an out-of-plane direction. Moreover, we analyzed the spin\nwave profile of the fundamental mode and the corresponding dynamic stray field.\nWe showed that the asymmetric application of surface anisotropy produces an\nasymmetric profile of dynamic stray field for square dot and can be used to\ntailor inter-dot coupling. The calculations were performed with the use of the\nfinite-element method.",
        "positive": "Uniform pseudomagnetic fields in graphene: corrections due to lattice\n  deformations: Very recently, the standard description of electrons in strained graphene has\nbeen completed by the explicit inclusion of the lattice deformation. Here, the\neffect of these lattice corrections is taken into account to find the\nmechanical deformations that generate a uniform pseudomagnetic field inside\nstrained graphene. The main difference when compared with previous proposals in\na rectangular geometry, is the need to stretch both zigzag and armchair edges."
    },
    {
        "anchor": "Plasmons and screening in finite-bandwidth 2D electron gas: The dynamical and nonlocal dielectric function of a two-dimensional electron\ngas (2DEG) with finite energy bandwidth is computed within random-phase\napproximation. For large bandwidth, the plasmon dispersion has two separate\nbranches at small and large momenta. The large momenta branch exhibits negative\nquasi-flat dispersion. The two branches merge with decreasing bandwidth. We\ndiscuss how the maximum energy plasmon mode which resides at energies larger\nthan all particle-hole continuum can potentially open a route to low-loss\nplasmons. Moreover, we discuss the bandwidth effects on the static screening of\nthe charged and magnetic impurities.",
        "positive": "Influence of Impurity Scattering on the Conductance Anomalies of Quantum\n  Point Contacts with Lateral Spin-Orbit Coupling: We have recently shown that asymmetric lateral spin orbit coupling (LSOC)\nresulting from the lateral in-plane electric field of the confining potential\nof a side-gated quantum point contact (QPC) can be used to create a strongly\nspin- polarized current by purely electrical means1 in the absence of applied\nmagnetic field. Using the non-equilibrium Green function formalism (NEGF)\nanalysis of a small model QPC2, three ingredients were found to be essential to\ngenerate the strong spin polarization: an asymmetric lateral confinement, a\nLSOC induced by the lateral confining potential of the QPC, and a strong\nelectron-electron (e-e) interaction. In this paper, NEGF is used to study how\nthe spin polarization is affected by the presence of impurities in the central\nportion of the QPC. It is found that the number, location, and shape of the\nconductance anomalies, occurring below the first quantized conductance plateau\n(G0=2e2/h), are strongly dependent on the nature (attractive or repulsive) and\nthe locations of the impurities. We show that the maximum of the conductance\nspin polarization is affected by the presence of impurities. For QPCs with\nimpurities off-center, a conductance anomaly appears below the first integer\nstep even for the case of symmetric bias on the two side gates. These results\nare of practical importance if QPCs in series are to be used to fabricate\nall-electrical spin valves with large ON/OFF conductance ratio."
    },
    {
        "anchor": "Filled Landau levels in neutral quantum gases: We consider the signatures of the Integer Quantum Hall Effect in a degenerate\ngas of electrically neutral atomic fermions. An effective magnetic field is\nachieved by applying two incident light beams with a high orbital angular\nmomentum. We show how states corresponding to completely filled Landau levels\nare obtained and discuss various possibilities to measure the incompressible\nnature of the trapped two-dimensional gas",
        "positive": "Acoustic phonon dynamics in thin-films of the topological insulator\n  Bi2Se3: Transient reflectivity traces measured for nanometer-sized films of the\ntopological insulator Bi2Se3 revealed GHz-range oscillations driven within the\nrelaxation of hot carriers photoexcited with ultrashort laser pulses of 1.51 eV\nphoton energy. These oscillations have been suggested to result from acoustic\nphonon dynamics, including coherent longitudinal acoustic phonons in the form\nof standing acoustic waves. An increase of oscillation frequency from ~35 to\n~70 GHz with decreasing film thickness from 40 to 15 nm was attributed to the\ninterplay between two different regimes employing traveling-acoustic-waves for\nfilms thicker than 40 nm and the film bulk acoustic wave resonator (FBAWR)\nmodes for films thinner than 40 nm. The amplitude of oscillations decays\nrapidly for films below 15 nm thick when the indirect intersurface coupling in\nBi2Se3 films switches the FBAWR regime to that of the Lamb wave excitation. The\nfrequency range of coherent longitudinal acoustic phonons is in good agreement\nwith elastic properties of Bi2Se3."
    },
    {
        "anchor": "A Graphene Quantum Dot with a Single Electron Transistor as Integrated\n  Charge Sensor: We have developed an etching process to fabricate a quantum dot and a nearby\nsingle electron transistor as a charge detector in a single layer graphene. The\nhigh charge sensitivity of the detector is used to probe Coulomb diamonds as\nwell as excited spectrum in the dot, even in the regime where the current\nthrough the quantum dot is too small to be measured by conventional transport\nmeans. The graphene based quantum dot and integrated charge sensor serve as an\nessential building block to form a solid-state qubit in a nuclear-spin-free\nquantum world.",
        "positive": "Nanosecond spin lifetimes in bottom-up fabricated bilayer graphene\n  spin-valves with atomic layer deposited Al$_2$O$_3$ spin injection and\n  detection barriers: We present spin transport studies on bi- and trilayer graphene non-local\nspin-valves which have been fabricated by a bottom-up fabrication method. By\nthis technique, spin injection electrodes are first deposited onto\nSi$^{++}$/SiO$_2$ substrates with subsequent mechanical transfer of a\ngraphene/hBN heterostructure. We showed previously that this technique allows\nfor nanosecond spin lifetimes at room temperature combined with carrier\nmobilities which exceed 20,000 cm$^2$/(Vs). Despite strongly enhanced spin and\ncharge transport properties, the MgO injection barriers in these devices\nexhibit conducting pinholes which still limit the measured spin lifetimes. We\ndemonstrate that these pinholes can be partially diminished by an oxygen\ntreatment of a trilayer graphene device which is seen by a strong increase of\nthe contact resistance area products of the Co/MgO electrodes. At the same\ntime, the spin lifetime increases from 1 ns to 2 ns. We believe that the\npinholes partially result from the directional growth in molecular beam\nepitaxy. For a second set of devices, we therefore used atomic layer deposition\nof Al$_2$O$_3$ which offers the possibility to isotropically deposit more\nhomogeneous barriers. While the contacts of the as-fabricated bilayer graphene\ndevices are non-conductive, we can partially break the oxide barriers by\nvoltage pulses. Thereafter, the devices also exhibit nanosecond spin lifetimes."
    },
    {
        "anchor": "Cavity Optomechanics: We review the field of cavity optomechanics, which explores the interaction\nbetween electromagnetic radiation and nano- or micromechanical motion. This\nreview covers the basics of optical cavities and mechanical resonators, their\nmutual optomechanical interaction mediated by the radiation pressure force, the\nlarge variety of experimental systems which exhibit this interaction, optical\nmeasurements of mechanical motion, dynamical backaction amplification and\ncooling, nonlinear dynamics, multimode optomechanics, and proposals for future\ncavity quantum optomechanics experiments. In addition, we describe the\nperspectives for fundamental quantum physics and for possible applications of\noptomechanical devices.",
        "positive": "Acoustic control of the lasing threshold in QDs ensemble coupled to an\n  optical microcavity: We propose a theoretical model which describes the coupling between quantum\ndots ensemble and optical microcavity. By this model we simulate the\ninteraction of the system with the strain pulse which can strongly modify the\nlasing of QDs."
    },
    {
        "anchor": "Fast Fabrication of WS2/Bi2Se3 Heterostructures for High Performance\n  Photodetection: Two-dimensional (2D) material heterostructures have attracted considerable\nattention owing to their interesting and novel physical properties, which\nexpand the possibilities for future optoelectronic, photovoltaic, and\nnanoelectronic applications. A portable, fast, and deterministic transfer\ntechnique is highly needed for the fabrication of heterostructures. Herein, we\nreport a fast half wet poly(dimethylsiloxane) (PDMS) transfer process utilizing\nthe change of adhesion energy with the help of micron-sized water droplets.\nUsing this method, a vertical stacking of the WS2/Bi2Se3 heterostructure with a\nstraddling band configuration is successfully assembled on a fluorophlogopite\nsubstrate. Thanks to the complementary band gaps and high efficiency of\ninterfacial charge transfer, the photodetector based on the heterostructure\nexhibits a superior responsivity of 109.9 A/W for a visible incident light at\n473 nm and 26.7 A/W for a 1064 nm near-infrared illumination. Such high\nphotoresponsivity of the heterostructure demonstrates that our transfer method\nnot only owns time efficiency but also ensures high quality of the\nheterointerface. Our study may open new pathways to the fast and massive\nfabrication of various vertical 2D heterostructures for applications in\ntwistronics/valleytronics and other band engineering devices.",
        "positive": "The magnetic, electronic, and light-induced topological properties in\n  two-dimensional hexagonal FeX2 (X = Cl, Br, I) monolayers: Topological materials are fertile ground for investigating topological phases\nof matter and topological phase transitions. In particular, the quest for novel\ntopological phases in 2D materials is attracting fast growing attention. Here,\nusing Floquet-Bloch theory, we propose to realize chiral topological phases in\n2D hexagonal FeX2 (X=Cl, Br, I) monolayers under irradiation of circularly\npolarized light. Such 2D FeX2 monolayers are predicted to be dynamical stable,\nand exhibit both ferromagnetic and semiconducting properties. To capture the\nfull topological physics of the magnetic semiconductor under periodic driving,\nwe adopt ab initio Wannier-based tight-binding methods for the Floquet-Bloch\nbands, with the light-induced band gap closings and openings being obtained as\nthe light field strength increases. The calculations of slab with open\nboundaries show the existence of chiral edge states. Interestingly, the\ntopological transitions with branches of chiral edge states changing from zero\nto one and from one to two by tuning the light amplitude are obtained, showing\nthat the topological floquet phase of high Chern number can be induced in the\npresent Floquet-Bloch systems."
    },
    {
        "anchor": "Contactless photo-induced carrier density control in nanocrystal MoS2\n  hybrids: The ultrathin nature of two-dimensional monolayer semiconductors yields\noptoelectronic properties which are highly responsive to changes in\nfree-carrier density, making it imperative to masterfully control their doping\nlevels. We report a new photo-doping scheme that quasi-permanently dopes the\nmonolayer MoS2 to extents competing with electrostatic gating. The photo-doping\nis achieved by coupling monolayer MoS2 with indium tin oxide nanocrystals that\ncan store multiple electrons per nanocrystal after UV illumination. In the\nhybrid structure, the photo-generated valence band holes in the nanocrystals\nare filled by MoS2 electrons, photo-doping the MoS2 with holes. Reductions in\ncarrier density by ~6x10^12 cm^-2 are observed, equivalent to the storage of\n~40 electrons per nanocrystal. Long-range changes proliferating up to 40\nmicrometers away from the localized photodoping result from local bandstructure\nvariations in MoS2. These studies reveal novel all-optical carrier density\ncontrol in monolayer semiconductors, enabling remote-control of local charge\ndensity and innovative energy storage technologies.",
        "positive": "Unified Treatment of Spin Torques using a Coupled Magnetisation Dynamics\n  and Three-Dimensional Spin Current Solver: A three-dimensional spin current solver based on a generalised spin\ndrift-diffusion description, including the spin Hall effect, is integrated with\na magnetisation dynamics solver. The resulting model is shown to simultaneously\nreproduce the spin-orbit torques generated using the spin Hall effect, spin\npumping torques generated by magnetisation dynamics in multilayers, as well as\nthe spin transfer torques acting on magnetisation regions with spatial\ngradients, whilst field-like and spin-like torques are reproduced in a spin\nvalve geometry. Two approaches to modelling interfaces are analysed, one based\non the spin mixing conductance and the other based on continuity of spin\ncurrents where the spin dephasing length governs the absorption of transverse\nspin components. In both cases analytical formulas are derived for the\nspin-orbit torques in a heavy metal / ferromagnet bilayer geometry, showing in\ngeneral both field-like and damping-like torques are generated. The limitations\nof the analytical approach are discussed, showing that even in a simple bilayer\ngeometry, due to the non-uniformity of the spin currents, a full\nthree-dimensional treatment is required. Finally the model is applied to the\nquantitative analysis of the spin Hall angle in Pt by reproducing published\nexperimental data on the ferromagnetic resonance linewidth in the bilayer\ngeometry."
    },
    {
        "anchor": "Piezoelectric electromechanical coupling in nanomechanical resonators\n  with two-dimensional electron gas: The electrical response of two-dimensional electron gas to vibrations of a\nnanomechanical cantilever containing it is studied. Vibrations of\nperpendicularly oriented cantilevers are experimentally shown to change\noppositely the conductivity near their bases. This indicates the piezoelectric\nnature of electromechanical coupling. A physical model is developed, which\nquantitatively explains the experiment. It shows that the main origin of the\nconductivity change is a rapid change in the mechanical stress on the boundary\nbetween suspended and non-suspended areas, rather than the stress itself.",
        "positive": "Strongly enhanced Berry dipole at topological phase transitions in BiTeI: Transitions between topologically distinct electronic states have been\npredicted in different classes of materials and observed in some. A major goal\nis the identification of measurable properties that directly expose the\ntopological nature of such transitions. Here we focus on the giant-Rashba\nmaterial bismuth tellurium iodine (BiTeI) which exhibits a pressure-driven\nphase transition between topological and trivial insulators in\nthree-dimensions. We demonstrate that this transition, which proceeds through\nan intermediate Weyl semi-metallic state, is accompanied by a giant enhancement\nof the Berry curvature dipole which can be probed in transport and\noptoelectronic experiments. From first-principles calculations, we show that\nthe Berrry-dipole --a vector along the polar axis of this material-- has\nopposite orientations in the trivial and topological insulating phases and\npeaks at the insulator-to-Weyl critical points, at which the nonlinear Hall\nconductivity can increase by over two orders of magnitude."
    },
    {
        "anchor": "Observation of Higher Order Nodal Line Semimetal in Phononic Crystals: Higher-order topological insulators and semimetals, which generalize the\nconventional bulk-boundary correspondence, have attracted extensive research\ninterest. Among them, higher-order Weyl semimetals feature two-fold linear\ncrossing points in three-dimensional (3D) momentum space, 2D Fermi-arc surface\nstates, and 1D hinge states. Higher-order nodal-point semimetals possessing\nWeyl points or Dirac points have been implemented. However, higher-order\nnodal-line or nodal-surface semimetals remain to be further explored in\nexperiments in spite of many previous theoretical efforts. In this work, we\nrealize a second-order nodal-line semimetal in 3D phononic crystals. The bulk\nnodal lines, 2D drumhead surface states guaranteed by Zak phases, and 1D flat\nhinge states attributed to kz-dependent quadrupole moments, are observed in\nsimulations and experiments. Our findings of nondispersive surface and hinge\nstates may promote applications in acoustic sensing and energy harvesting.",
        "positive": "Moire-enabled artificial topological superconductivity in twisted\n  bilayer graphene: Twisted van der Waals materials have risen as highly tunable platform for\nrealizing unconventional superconductivity. Here we demonstrate how a\ntopological superconducting state can be driven in a twisted graphene\nmultilayer at a twist angle of approximately 1.6 degrees proximitized to other\n2D materials. We show that an encapsulated twisted bilayer subject to induced\nRashba spin-orbit coupling, s-wave superconductivity and exchange field\ngenerates a topological superconducting state enabled by the moire pattern. We\ndemonstrate a variety of topological states with different Chern numbers highly\ntunable through doping, strain and bias voltage. Our proposal does not depend\non a fine tuning of the twist angle, but solely on the emergence of moire\nminibands and is applicable for twist angles between 1.3 and 3 degrees. Our\nresults establish the potential of twisted graphene bilayers to create\nartificial topological superconductivity without requiring ultraflat\ndispersions."
    },
    {
        "anchor": "Ultrahigh Q-Frequency product for optomechanical disk resonators with a\n  mechanical shield: We report on optomechanical GaAs disk resonators with ultrahigh quality\nfactor - frequency product Qf. Disks standing on a simple pedestal exhibit GHz\nbreathing modes attaining a Qf of 10^13 measured under vacuum at cryogenic\ntemperature. Clamping losses are found to be the dominant source of dissipation\nin this configuration. A new type of disk resonator integrating a shield within\nthe pedestal is then proposed and its working principles and performances\ninvestigated by numerical simulations. For dimensions compatible with\nfabrication constraints, the clamping-loss-limited Q reaches 10^7-10^9\ncorresponding to Qf of 10^16-10^18. This shielded pedestal approach applies to\nany heterostructure presenting an acoustic mismatch.",
        "positive": "Many-body electron correlations in graphene: The conduction electrons in graphene promise new opportunities to access the\nregion of strong many-body electron-electron correlations. Extremely high\nquality, atomically flat two-dimensional electron sheets and\nquasi-one-dimensional electron nanoribbons with tuneable band gaps that can be\nswitched on by gates, should exhibit new many-body phenomena that have long\nbeen predicted for the regions of phase space where the average Coulomb\nrepulsions between electrons dominate over their Fermi energies. In electron\nnanoribbons a few nanometres wide etched in monolayers of graphene, the quantum\nsize effects and the van Hove singularities in their density of states further\nact to enhance electron correlations. For graphene multilayers or nanoribbons\nin a double unit electron-hole geometry, it is possible for the many-body\nelectron-hole correlations to be made strong enough to stabilise\nhigh-temperature electron-hole superfluidity."
    },
    {
        "anchor": "Photogalvanic effect and photoconductance in a quantum channel with a\n  single short-range scatterer: The influence of electromagnetic radiation on the electron transport in a\nquantum channel with a single short-range scatterer is investigated using a\ngeneralized Landauer-Buttiker approach. We have shown that asymmetrical\nposition of the scatterer leads to appearance of the direct photocurrent in the\nsystem. The dependence of the photocurrent on the electron chemical potential,\nthe position of the scatterer, and the frequency of the radiation is studied.\nWe have shown that the photocurrent and the photoconductance oscillate as\nfunctions of the electron chemical potential. The nature of oscillations is\ndiscussed.",
        "positive": "Progress in epitaxial thin-film Na3Bi as a topological electronic\n  material: Na3Bi was the first experimentally verified topological Dirac semimetal\n(TDS), and is a 3D analogue of graphene hosting relativistic Dirac fermions.\nIts unconventional momentum-energy relationship is interesting from a\nfundamental perspective, yielding exciting physical properties such as chiral\ncharge carriers, the chiral anomaly, and weak anti-localization. It also shows\npromise for realising topological electronic devices such as topological\ntransistors.\n  In this review, an overview of the substantial progress achieved in the last\nfew years on Na3Bi is presented, with a focus on technologically relevant\nlarge-area thin films synthesised via molecular beam epitaxy. Key theoretical\naspects underpinning the unique electronic properties of Na3Bi are introduced.\nNext, the growth process on different substrates is reviewed. Spectroscopic and\nmicroscopic features are illustrated, and an analysis of semi-classical and\nquantum transport phenomena in different doping regimes is provided. The\nemergent properties arising from confinement in two dimensions, including\nthickness-dependent and electric-field driven topological phase transitions,\nare addressed, with an outlook towards current challenges and expected future\nprogress."
    },
    {
        "anchor": "Anisotropic chiral magnetic effect from tilted Weyl cones: We determine the antisymmetric current-current response for a pair of (type\nI) tilted Weyl cones with opposite chirality. We find that the dynamical chiral\nmagnetic effect depends on the magnitude of the tilt and on the angle between\nthe tilting direction and the wave vector of the magnetic field. Additionally,\nthe chiral magnetic effect is shown to be closely related to the presence of an\nintrinsic anomalous Hall effect with a current perpendicular to the tilting\ndirection and the electric field. We investigate the nonanalytic\nlong-wavelength limit of the corresponding transport coefficients.",
        "positive": "Interatomic potentials for the vibrational properties of III-V\n  semiconductor nanostructures: We derive interatomic potentials for zinc blende InAs, InP, GaAs and GaP\nsemiconductors with possible applications in the realm of nanostructures. The\npotentials include bond stretching interaction between the nearest and\nnext-nearest neighbors, a three body term and a long-range Coulomb interaction.\nThe optimized potential parameters are obtained by (i) fitting to bulk phonon\ndispersions and elastic properties and (ii) constraining the parameter space to\ndeliver well behaved potentials for the structural relaxation and vibrational\nproperties of nanostructure clusters. The targets are thereby calculated by\ndensity functional theory for clusters of up to 633 atoms. We illustrate the\nnew capability by the calculation Kleinman and Gr\\\"uneisen parameters and of\nthe vibrational properties of nanostructures with 3 to 5.5 nm diameter."
    },
    {
        "anchor": "Boundary Green's function approach for spinful single-channel and\n  multichannel Majorana nanowires: The boundary Green's function (bGF) approach has been established as a\npowerful theoretical technique for computing the transport properties of\ntunnel-coupled hybrid nanowire devices. Such nanowires may exhibit\ntopologically nontrivial superconducting phases with Majorana bound states at\ntheir boundaries. We introduce a general method for computing the bGF of\nspinful multi-channel lattice models for such Majorana nanowires, where the bGF\nis expressed in terms of the roots of a secular polynomial evaluated in complex\nmomentum space. In many cases, those roots, and thus the bGF, can be accurately\ndescribed by simple analytical expressions, while otherwise our approach allows\nfor the numerically efficient evaluation of bGFs. We show that from the\nbehavior of the roots, many physical quantities of key interest can be\ninferred, e.g., the value of bulk topological invariants, the energy dependence\nof the local density of states, or the spatial decay of subgap excitations. We\napply the method to single- and two-channel nanowires of symmetry class D or\nDIII. In addition, we study the spectral properties of multi-terminal Josephson\njunctions made out of such Majorana nanowires.",
        "positive": "Bulk and edge excitations of a $\u03bd=1$ Hall ferromagnet: In this article, we shall focus on the collective dynamics of the fermions in\na $\\nu = 1$ quantum Hall droplet. Specifically, we propose to look at the\nquantum Hall ferromagnet. In this system, the electron spins are ordered in the\nground state due to the exchange part of the Coulomb interaction and the Pauli\nexclusion principle. The low energy excitations are ferromagnetic magnons. In\norder to obtain an effective Lagrangian for these magnons, we shall introduce\nbosonic collective coordinates in the Hilbert space of many-fermion systems.\nThese collective coordinates describe a part of the fermionic Hilbert space.\nUsing this technique, we shall interpret the magnons as bosonic collective\nexcitations in the Hilbert space of the many-electron Hall system. Furthermore,\nby considering a Hall droplet of finite extent, we shall also obtain the\neffective Lagrangian governing the spin collective excitations at the edge of\nthe sample."
    },
    {
        "anchor": "Magnetoresistance of monolayer graphene with short-range scattering: We present magnetotransport measurements at classical magnetic fields for\nthree graphene monolayers with various levels of disorder. A square root\nmagnetoresistance (SRMR) behavior is observed in one sample which has the\ncharacteristic sub-linear conductivity signaling on the presence of short-range\ndisorder in this sample. No square root MR was observed in other samples where\nshort-range scattering is inessential as it is evident from the gate voltage\ndependences of their conductivities. Comparing our experimental data for the\nsample with theoretical calculations we found a good qualitative agreement and\nestablished the conditions which should be fulfilled in graphene to observe the\nSRMR experimentally.",
        "positive": "Topological Heat Transport and Symmetry-Protected Boson Currents: The study of non-equilibrium properties in topological systems is of\npractical and fundamental importance. Here, we analyze the stationary\nproperties of a two-dimensional bosonic Hofstadter lattice coupled to two\nthermal baths in the quantum open-system formalism. Novel phenomena appear like\nchiral edge heat currents that are the out-of-equilibrium counterparts of the\nzero-temperature edge currents. They support a new concept of dissipative\nsymmetry-protection, where a set of discrete symmetries protects topological\nheat currents, differing from the symmetry-protection devised in closed systems\nand zero-temperature. Remarkably, one of these currents flows opposite to the\ndecreasing external temperature gradient. As the starting point, we consider\nthe case of a single external reservoir already showing prominent results like\nthermal erasure effects and topological thermal currents. Our results are\nexperimentally accessible with platforms like photonics systems and optical\nlattices."
    },
    {
        "anchor": "Measuring electron spin flip-flops through nuclear spin echo decays: We use the nuclear spin coherence of $^{31}$P donors in $^{28}$Si to\ndetermine flip-flop rates of donor electron spins. Isotopically purified\n$^{28}$Si crystals minimize the number of $^{29}$Si flip-flops, and\nmeasurements at 1.7 K suppress electron spin relaxation. The crystals have\ndonor concentrations ranging from $1.2\\times10^{14}$ to\n$3.3\\times10^{15}~\\text{P/cm}^3$, allowing us to detect how electron flip-flop\nrates change with donor density. We also simulate how electron spin flip-flops\ncan cause nuclear spin decoherence. We find that when these flip-flops are the\nprimary cause of decoherence, Hahn echo decays have a stretched exponential\nform. For our two higher donor density crystals ($> 10^{15}~\\text{P/cm}^3$),\nthere is excellent agreement between simulations and experiments. In lower\ndensity crystals ($< 10^{15}~\\text{P/cm}^3$), there is no longer agreement\nbetween simulations and experiments, suggesting a different, unknown mechanism\nis limiting nuclear spin coherence. The nuclear spin coherence in the lowest\ndensity crystal ($1.2 \\times 10^{14}~\\text{P/cm}^3$) allows us to place upper\nbounds on the magnitude of noise sources in bulk crystals such as electric\nfield fluctuations that may degrade silicon quantum devices.",
        "positive": "Q-factor control of a microcantilever by mechanical sideband excitation: We demonstrate the coupling between the fundamental and second flexural mode\nof a microcantilever. A mechanical analogue of cavity-optomechanics is then\nemployed, where the mechanical cavity is formed by the second vibrational mode\nof the same cantilever, coupled to the fundamental mode via the geometric\nnonlinearity. By exciting the cantilever at the sum and difference frequencies\nbetween fundamental and second flexural mode, the motion of the fundamental\nmode of the cantilever is amplified and damped. This concept makes it possible\nto enhance or suppress the Q-factor over a wide range."
    },
    {
        "anchor": "Current modulation in graphene p-n junctions with external fields: In this work we describe a proposal for a graphene-based nanostructure that\nmodulates electric current even in the absence of a gap in the band structure.\nThe device consists of a graphene p-n junction that acts as a Veselago lens\nthat focuses ballistic electrons on the output lead. Applying external\n(electric and magnetic) fields changes the position of the output focus,\nreducing the transmission. Such device can be applied to low power field effect\ntransistors, which can benefit from graphene's high electronic mobility.",
        "positive": "Device model for pixelless infrared image up-converters based on\n  polycrystalline graphene heterostructures: We develop a device model for pixelless converters of far/mid-infrared\nradiation (FIR/MIR) images into near-infrared/visible (NIR/VIR) images. These\nconverters use polycrystalline graphene layers (PGLs) immersed in the van der\nWaals (vdW) materials integrated with light emitting diode (LED). The PGL\nserves as an element of the PGL infrared photodetector (PGLIP) sensitive to the\nincoming FIR/MIR due to the interband absorption. The spatially non-uniform\nphotocurrent generated in the PGLIP repeats (mimics) the non-uniform\ndistribution (image) created by the incident FIR/MIR. The injection of the\nnonuniform photocurrent into the LED active layer results in the nonuniform\nNIR/VIR image reproducing the FIR/MIR image. The PGL and the entire layer\nstructure are not deliberately partitioned into pixels. We analyze the\ncharacteristics of such pixelless PGLIP-LED up-converters and show that their\nimage contrast transfer function and the up-conversion efficiency depend on the\nPGL lateral resistivity. The up-converter exhibits high photoconductive gain\nand conversion efficiency when the lateral resistivity is sufficiently high.\nSeveral teams have successfully demonstrated the large area PGLs with the\nresistivities varying in a wide range. Such layers can be used in the pixelless\nPGLIP-LED image up-converters. The PGLIP-LED image up-converters can\nsubstantially surpass the image up-converters based on the quantum-well\ninfrared photodetector (QWIP) integrated with the LED. These advantages are due\nto the use of the interband FIR/NIR absorption and a high photoconductive gain\nin the GLIPs."
    },
    {
        "anchor": "Probing nanoscale thermal transport with cathodoluminescence thermometry: Thermal properties have an outsized impact on efficiency and sensitivity of\ndevices with nanoscale structures, such as in integrated electronic circuits. A\nnumber of thermal conductivity measurements for semiconductor nanostructures\nexist, but are hindered by the diffraction limit of light, the need for\ntransducer layers, the slow-scan rate of probes, ultra-thin sample\nrequirements, or extensive fabrication. Here, we overcome these limitations by\nextracting temperature from measurements of bandgap cathodoluminescence in GaN\nnanowires with spatial resolution limited by the electron cascade, and use this\nto determine thermal conductivities in the range of 19-68 W/m*K in three new\nways. The electron beam acts simultaneously as a temperature probe and as a\ncontrolled delta-function-like heat source to measure thermal conductivities\nusing steady-state methods, and we introduce a frequency-domain method using\npulsed electron beam excitation. The different thermal conductivity\nmeasurements we explore agree within error where comparable. Our results\nprovide novel methods of measuring thermal properties that allow for rapid,\nin-situ, high-resolution measurements of integrated circuits and semiconductor\nnanodevices, and open the door for electron-beam based nanoscale phonon\ntransport studies.",
        "positive": "Modeling friction: From nanoscale to mesoscale: The physics of sliding friction is gaining impulse from nanoscale and\nmesoscale experiments, simulations, and theoretical modeling. This Colloquium\nreviews some recent developments in modeling and in atomistic simulation of\nfriction, covering open-ended directions, unconventional nanofrictional\nsystems, and unsolved problems."
    },
    {
        "anchor": "The effect of surface geometry on collisions between nanoparticles: In this molecular dynamics study, we examine the local surface geometric\neffects of the normal impact force between two approximately spherical\nnanoparticles that collide in a vacuum. Three types of surface geometries,\nfacets, sharp crystal edges, and amorphous surfaces of nanoparticles with radii\nR < 10 nm are considered, and the impact force is compared with its macroscopic\ncounterpart described by a nonlinear contact force, FN proportional to D with n\n= 3/2 derived by Hertz (1881), where D is the overlap induced by elastic\ncompression. We study the surface geometry-dependent impact force. For\nfacet-facet impact, the mutual contact surface area does not expand due to the\nlarge facet surface, and this in turn leads to a non-Hertz impact force, n <\n3/2. A Hertz-like contact force, n = 1.5, is recovered in the edge contact and\nin the amorphous surface contact, allowing expansion of the mutual contact\nsurface area. The results suggest that collisions of amorphous nanoparticles or\nnanoparticles with sharp edges may maintain dynamic phenomena, such as\nbreathers and solitary waves, originating from the nonlinear contact force.",
        "positive": "Quantum transport in oxide nanostructures: We describe magnetotransport experiments performed on Hall crosses made from\nquantum wires at LaAlO3/SrTiO3 interfaces. Shubnikov-de Haas oscillations\nmeasured in a 14-nm wide structure exhibit modulations that are consistent with\nspin-orbit coupling or valley degeneracies. Hall measurements performed on the\n6 nm-wide Hall cross reveal dissipative coupling to magnetic phases. Hall\nplateaus are observed that deviate significantly from two-dimensional quantum\nHall counterparts. Non-monotonic dips in the Hall resistance are attributed to\none-dimensional confinement and spin-orbit coupling."
    },
    {
        "anchor": "Change of Corner Charge and Adiabatic Current Distribution in Two\n  Dimensional Insulators with Inversion Symmetry: We discuss the change of the corner charge for noninteracting two dimensional\ninsulators with inversion symmetry undergoing adiabatic evolution. We show that\nthe change of the corner charge is accounted for by the adiabatic current\nflowing along the edges of the system. The study of systems with quasi-1D\ngeometry is necessary to derive the analytical expression for the adiabatic\ncurrent. This fact suggests that the change of the corner charge is neither a\npurely bulk nor edge effect, but rather a mixed one. The derived adiabatic\ncurrent was examined and shows good agreement with the numerical calculation of\nBenalcazar-Bernevig-Hughes model.",
        "positive": "Hybrid Superconductor-Quantum Point Contact Devices using InSb Nanowires: Proposals for studying topological superconductivity and Majorana bound\nstates in nanowires proximity coupled to superconductors require that transport\nin the nanowire is ballistic. Previous work on hybrid nanowire-superconductor\nsystems has shown evidence for Majorana bound states, but these experiments\nwere also marked by disorder, which disrupts ballistic transport. In this\nletter, we demonstrate ballistic transport in InSb nanowires interfaced\ndirectly with superconducting Al by observing quantized conductance at\nzero-magnetic field. Additionally, we demonstrate that the nanowire is\nproximity coupled to the superconducting contacts by observing Andreev\nreflection. These results are important steps for robustly establishing\ntopological superconductivity in InSb nanowires."
    },
    {
        "anchor": "Graphene nanopore devices for DNA sequencing: A tight-binding model\n  study: We present a tight-binding model study of a two-terminal graphene nanopore\ndevice for sequential determination of DNA bases. Using Green's function\ntechnique we investigate the changes in electronic transport properties of the\ndevice due to insertion of different nucleotides into the nanopore created\nwithin a zigzag graphene nanoribbon. First we try to characterise the device in\nstatic condition and then go for sequencing application by setting the bias\nacross it to a specific voltage and then recording the characteristic current\nsignals corresponding to each nucleotides of a translocating DNA. Our\ninvestigations show that graphene nanopores can certainly become very efficient\nand reliable for sequencing applications in future.",
        "positive": "Landau Quantization in Twisted Bilayer Graphenes: the Dirac Comb: We study the Landau quantization of the electronic spectrum for graphene\nbilayers that are rotationally faulted to produce periodic superlattices.\nCommensurate twisted bilayers exist in two families distinguished by their\nsublattice exchange parity. We show that these two families exhibit distinct\nLandau quantized spectra distinguished both by the interlayer coupling of their\nzero modes and by an amplitude modulation of their spectra at energies above\ntheir low energy interlayer coherence scales. These modulations can provide a\npowerful experimental probe of the magnitude of a weak coherence splitting in a\nbilayer and its low energy mass structure."
    },
    {
        "anchor": "Field enhanced electron mobility by nonlinear phonon scattering of Dirac\n  electrons in semiconducting graphene nanoribbons: The calculated electron mobility for a graphene nanoribbon as a function of\napplied electric field has been found to have a large threshold field for\nentering a nonlinear transport regime. This field depends on the lattice\ntemperature, electron density, impurity scattering strength, nanoribbon width\nand correlation length for the line-edge roughness. An enhanced electron\nmobility beyond this threshold has been observed, which is related to the\ninitially-heated electrons in high energy states with a larger group velocity.\nHowever, this mobility enhancement quickly reaches a maximum due to the Fermi\nvelocity in graphene and the dramatically increased phonon scattering.\nSuper-linear and sub-linear temperature dependence of mobility seen in the\nlinear and nonlinear transport regimes. By analyzing the calculated\nnon-equilibrium electron distribution function, this difference is attributed\nseparately to the results of sweeping electrons from the right Fermi edge to\nthe left one through the elastic scattering and moving electrons from\nlow-energy states to high-energy ones through field-induced electron heating.\nThe threshold field is pushed up by a decreased correlation length in the high\nfield regime, and is further accompanied by a reduced magnitude in the mobility\nenhancement. This implies an anomalous high-field increase of the line-edge\nroughness scattering with decreasing correlation length due to the occupation\nof high-energy states by field-induced electron heating.",
        "positive": "Interminiband Rabi oscillations in biased semiconductor superlattices: Carrier dynamics at energy level anticrossings in biased semiconductor\nsuperlattices, was studied in the time domain by solving the time-dependent\nSchroedinger equation. The resonant nature of interminiband Rabi oscillations\nhas been explicitly demonstrated to arise from interference of intrawell and\nBloch oscillations. We also report a simulation of direct Rabi oscillations\nacross three minibands, in the high field regime, due to interaction between\nthree strongly coupled minibands."
    },
    {
        "anchor": "Fano versus Kondo Resonances in a Multilevel \"Semi-Open\" Quantum Dot: Linear conductance across a large quantum dot via a single level e_0 with\nlarge hybridization to the contacts is strongly sensitive to quasi-bound states\nlocalized in the dot and weakly coupled to e_0. It oscillates with the gate\nvoltage due to interference of the Fano type. At low temperature and Coulomb\nblockade, Kondo correlations damp the oscillations on an extended range of gate\nvoltage values, by freezing the occupancy of the e_0 level itself. As a\nconsequence, antiresonances of Fano origin are washed out. The results are in\ngood correspondence with experimental data for a large quantum dot in the\nsemi-open regime.",
        "positive": "Evolution of the Spin Hall Magnetoresistance in Cr$_2$O$_3$/Pt bilayers\n  close to the N\u00e9el temperature: We study the evolution of magnetoresistance with temperature in thin film\nbilayers consisting of platinum and the antiferromagnet Cr$_2$O$_3$ with its\neasy axis out of the plane. We vary the temperature from 20 - 60{\\deg}C, close\nto the N\\'eel temperature of Cr$_2$O$_3$ of approximately 37{\\deg}C. The\nmagnetoresistive response is recorded during rotations of the external magnetic\nfield in three mutually orthogonal planes. A large magnetoresistance having a\nsymmetry consistent with a positive spin Hall magnetoresistance is observed in\nthe paramagnetic phase of the Cr$_2$O$_3$, which however vanishes when cooling\nto below the N\\'eel temperature. Comparing to analogous experiments in a\nGd$_3$Ga$_5$O$_{12}$/Pt heterostructure, we conclude that a paramagnetic field\ninduced magnetization in the insulator is not sufficient to explain the\nobserved magnetoresistance. We speculate that the type of magnetic moments at\nthe interface qualitatively impacts the spin angular momentum transfer, with\nthe $3d$ moments of Cr sinking angular momentum much more efficiently as\ncompared to the more localized $4f$ moments of Gd."
    },
    {
        "anchor": "Bloch-Lorentz magnetoresistance oscillations in delafossites: Recent measurements of the out-of-plane magnetoresistance of delafossites\n(PdCoO$_2$ and PtCoO$_2$) observed oscillations closely resembling the\nAharonov-Bohm effect. Here, we show that the magnetoresistance oscillations are\nexplained by the Bloch-like oscillations of the out-of-plane electron\ntrajectories. We develop a semiclassical theory of these Bloch-Lorentz\noscillations and show that they are a consequence of the ballistic motion and\nquasi-2D dispersion of delafossites. Our model identifies the sample wall\nscattering to be the most likely factor limiting the visibility of these\nBloch-Lorentz oscillations in existing experiments.",
        "positive": "Josephson current in a superconductor -- ferromagnet -- superconductor\n  junction with in-plane ferromagnetic domains: We study a diffusive superconductor--ferromagnet--superconductor (SFS)\njunction with in-plane ferromagnetic domains. Close to the superconducting\ntransition temperature, we describe the proximity effect in the junction with\nthe linearized Usadel equations. We find that properties of such a junction\ndepend on the size of the domains relative to the magnetic coherence length. In\nthe case of large domains, the junction exhibits transitions to the $\\pi$\nstate, similarly to a single-domain SFS junction. In the case of small domains,\nthe magnetization effectively averages out, and the junction is always in the\nzero state, similarly to a superconductor--normal metal--superconductor (SNS)\njunction. In both those regimes, the influence of domain walls may be\napproximately described as an effective spin-flip scattering. We also study the\ninhomogeneous distribution of the local current density in the junction. Close\nto the 0--$\\pi$ transitions, the directions of the critical current may be\nopposite in the vicinity of the domain wall and in the middle of the domains."
    },
    {
        "anchor": "Exact analysis of gate noise effects on non-adiabatic transformations of\n  spin-orbit qubits: We considered various types of potential noise in gates controlling\nnon-adiabatic holonomic transformations of spin-qubits in one and two\ndimensional systems with the Rashba interaction. It is shown how exact results\ncan be derived for deviations of spin rotation angle and fidelity of the qubit\ntransformation after a completed transformation. Errors in initial values of\ngate potentials and time-dependent drivings are considered and exact results\nfor white gate noise are derived and analysed in detail. It is demonstrated how\nthe drivings can be tuned to optimise the final fidelity of the transformation\nand to minimise the variances of qubit transformations.",
        "positive": "Floquet Exceptional Topological Insulator: We propose a novel way of modulating exceptional topology by implementing\nFloquet engineering in non-hermitian (NH) systems. We introduce Floquet\nexceptional topological insulator which results from shining light on a\nconventional three-dimensional NH topological insulator. Lightmatter\ninteraction facilitates the quantum phases of matter to exhibit a novel\nphenomenon, where, the point gaps in the bulk host surface states. These\ndistinct surface states either fill the point gap in the complex eigenspectrum\nor exhibit exceptional points in the presence of a magnetic field. We also\nhighlight the existence of a quantum anomaly generated by photo-induced\nmodulation. The existence of the Floquet biorthogonal Chern number and spectral\nwinding number show that the momentum slices exhibit NH skin effect, even\nthough the system as a whole does not. We also employ wave-dynamics evolution\nto illustrate the NH surface skin effect."
    },
    {
        "anchor": "Quantum impurity approach to a coupled qubit problem: We consider a system of two qubits at the ends of a finite length 1D cavity.\nThis problem is mapped onto the double-Kondo model which is also shown to\ndescribe the low energy physics of a finite length quantum wire with resonant\nlevels at its ends. At the Toulouse point the ground state energy and the\naverage populations and correlations of the qubits or resonant levels at zero\ntemperature are computed. These results show that the effective interactions\nbetween the qubits or resonant levels can be used to probe their associated\nKondo length scale.",
        "positive": "Observation of the Accelerated Diffusion in Nanoparticles of\n  Paradibromobenzene /Paradihlorbenzene Solid Solution: P-dibromobenzene nanoparticles in a case of paradihlorbenzol molecules have\nbeen synthesized. Raman spectrums of these nanoparticles are measured. At\ndiffusion of molecules of paradihlorbenzol in a pdibromobenzene nanoparticle\nsolid solution formed. Modifications in structure of nanoparticles at diffusion\nare reflected in Raman spectrums. Unlike a solid solution single crystal, in\nnanoparticles the accelerated diffusion, $D = 1.3 \\pm 0.02 10^{-11} cm^2/s$, is\nobserved at room temperature. Calculations show that the accelerated diffusion\nis caused by magnification of parametres of a lattice at reduction of sizes of\nnanoparticles."
    },
    {
        "anchor": "Generalized multi-terminal decoherent transport: Recursive algorithms\n  and applications to SASER and giant magnetoresistance: Decoherent transport in mesoscopic and nanoscopic systems can be formulated\nin terms of the D'Amato-Pastawski (DP) model. This generalizes the\nLandauer-B\\\"{u}ttiker picture by considering a distribution of local decoherent\nprocesses. However, its generalization for multi-terminal setups is lacking. We\nfirst review the original two-terminal DP model for decoherent transport. Then,\nwe extend it to a matrix formulation capable of dealing with multi-terminal\nproblems. We also introduce recursive algorithms to evaluate the Green's\nfunctions for general banded Hamiltonians as well as local density of states,\neffective conductances and voltage profiles. We finally illustrate the method\nby analyzing two problems of current relevance. 1) Assessing the role of\ndecoherence in a model for phonon lasers (SASER). 2) Obtaining the classical\nlimit of Giant Magnetoresistance from a spin-dependent Hamiltonian. The\npresented methods should pave the way for computationally demanding\ncalculations of transport through nanodevices, bridging the gap between fully\ncoherent quantum schemes and semiclassical ones.",
        "positive": "Photoluminescence and Raman investigation of stability of InSe and GaSe\n  thin films: Layered III-chalcogenide compounds belong to a variety of layered crystals\nthat can be implemented in van der Waals heterostructures. Here we report an\noptical study of the stability of two of these compounds: indium selenide\n(InSe) and gallium selenide (GaSe). Micro-photoluminescence (PL) and Raman\nspectroscopy are used to determine how the properties of thin films of these\nmaterials change when they are exposed to air at room temperature. We find that\nin GaSe films, PL signal decreases on average below 50% over 24 (72) hours of\nexposure for films with thicknesses 10-25 (48-75) nm. In contrast, weak PL\ndecrease of less than 20% is observed for InSe nm films after exposure of 100\nhours. Similar trends are observed in Raman spectroscopy: within a week, the\nRaman signal decreases by a factor of 10 for a 24 nm thick GaSe, whereas no\ndecrease was found for a 16 nm InSe film. We estimate that when exposed to air,\nthe layers adjacent to the GaSe film surface degrade and become non-luminescent\nwith a rate of 0.14$\\pm$0.05 nm/hour. We show that the life-time of the GaSe\nfilms can be increased by up to two orders of magnitude (to several months) by\nencapsulation in dielectric materials such as SiO$_2$ or Si$_x$N$_y$."
    },
    {
        "anchor": "Synthetic dimensions and topological chiral currents in mesoscopic rings: The recently-introduced concept of \"synthetic dimensions\" allows for the\nrealization of higher-dimensional topological phenomena in lower-dimensional\nsystems. In this work we study the complementary aspect that synthetic\ndimensions provide a natural route to topological states in mesoscopic hybrid\ndevices. We demonstrate this for the current induced into a closed\none-dimensional Aharonov-Bohm ring by the interaction with a dynamic mesoscopic\nmagnet. The quantization of the magnetic moment provides a synthetic dimension\nthat complements the charge motion around the ring. We present a direct mapping\nthat places the combined ring-magnet system into the class of quantum Hall\nmodels, and demonstrate that topological features, combined with the magnet's\nanisotropy, can lead to clear signatures in the persistent current of the\nsingle-particle ground state.",
        "positive": "Semiclassical Monte Carlo Model for In-Plane Transport of Spin-Polarized\n  Electrons in III-V Heterostructures: We study the in-plane transport of spin-polarized electrons in III-V\nsemiconductor quantum wells. The spin dynamics is controlled by the spin-orbit\ninteraction, which arises via the Dresselhaus (bulk asymmetry) and Rashba (well\nasymmetry) mechanisms. This interaction, owing to its momentum dependence,\ncauses rotation of the spin polarization vector, and also produces effective\nspin dephasing. The density matrix approach is used to describe the evolution\nof the electron spin polarization, while the spatial motion of the electrons is\ntreated semiclassically. Monte Carlo simulations have been carried out for\ntemperatures in the range 77-300 K."
    },
    {
        "anchor": "Coherent control of single electrons: a review of current progress: In this report we review the present state of the art of the control of\npropagating quantum states at the single-electron level and its potential\napplication to quantum information processing. We give an overview of the\ndifferent approaches which have been developed over the last ten years in order\nto gain full control over a propagating single electron in a solid state\nsystem. After a brief introduction of the basic concepts, we present\nexperiments on flying qubit circuits for ensemble of electrons measured in the\nlow frequency (DC) limit. We then present the basic ingredients necessary to\nrealise such experiments at the single-electron level. This includes a review\nof the various single electron sources which are compatible with integrated\nsingle electron circuits. This is followed by a review of recent key\nexperiments on electron quantum optics with single electrons. Finally we will\npresent recent developments about the new physics that emerges using ultrashort\nvoltage pulses. We conclude our review with an outlook and future challenges in\nthe field.",
        "positive": "Barnett Effect in Thin Magnetic Films and Nanostructures: The Barnett effect refers to the magnetization induced by rotation of a\ndemagnetized ferromagnet. We describe the location and stability of stationary\nstates in rotating nanostructures using the Landau-Lifshitz-Gilbert equation.\nThe conditions for an experimental observation of the Barnett effect in\ndifferent materials and sample geometries are discussed."
    },
    {
        "anchor": "Rewritable nanoscale oxide photodetector: Nanophotonic devices seek to generate, guide, and/or detect light using\nstructures whose nanoscale dimensions are closely tied to their functionality.\nSemiconducting nanowires, grown with tailored optoelectronic properties, have\nbeen successfully placed into devices for a variety of applications. However,\nthe integration of photonic nanostructures with electronic circuitry has always\nbeen one of the most challenging aspects of device development. Here we report\nthe development of rewritable nanoscale photodetectors created at the interface\nbetween LaAlO3 and SrTiO3. Nanowire junctions with characteristic dimensions\n2-3 nm are created using a reversible AFM writing technique. These nanoscale\ndevices exhibit a remarkably high gain for their size, in part because of the\nlarge electric fields produced in the gap region. The photoconductive response\nis gate-tunable and spans the visible-to-near-infrared regime. The ability to\nintegrate rewritable nanoscale photodetectors with nanowires and transistors in\na single materials platform foreshadows new families of integrated\noptoelectronic devices and applications.",
        "positive": "Upstanding Rashba spin in honeycomb lattices: Electrically reversible\n  surface spin polarization: The spin-split states subject to Rashba spin-orbit coupling in\ntwo-dimensional systems have long been accepted as pointing inplane and\nperpendicular to the corresponding wave vectors. This is in general true for\nfree electron model, but exceptions do exist elsewhere. Within the\ntight-binding model, we unveil the unusual upstanding behavior of those Rashba\nspins around $\\bar{K}$ and $\\bar{K}^{\\prime}$ points in honeycomb lattices. Our\ncalculation (i) explains the recent experiment of the Tl/Si(111)-$(1\\times1)$\nsurface alloy [Phys. Rev. Lett. \\textbf{102}, 096805 (2009)], where abrupt\nupstanding spin states near $\\bar{K}$ are observed, and (ii) predicts an\nelectrically reversible out-of-plane surface spin polarization."
    },
    {
        "anchor": "Calculation of Confined Phonon Spectrum in Narrow Silicon Nanowires\n  using the Valence Force Field Method: We study the effect of confinement on the phonon properties of ultra-narrow\nsilicon nanowires of side sizes of 1-10nm . We use the modified valence force\nfield method to compute the phononic dispersion, and extract the density of\nstates, the transmission function, the sound velocity, the ballistic thermal\nconductance and boundary scattering-limited diffusive thermal conductivity. We\nfind that the phononic dispersion and the ballistic thermal conductance are\nfunctions of the geometrical features of the structures, i.e. the transport\norientation and confinement dimension. The phonon group velocity and thermal\nconductance can vary by a factor of two depending on the geometrical features\nof the channel. The <110> nanowire has the highest group velocity and thermal\nconductance, whereas the <111> the lowest. The <111> channel is thus the most\nsuitable orientation for thermoelectric devices based on Si nanowires since it\nalso has a large power factor. Our findings could be useful in the thermal\ntransport design of silicon-based devices for thermoelectric and thermal\nmanagement applications.",
        "positive": "Exceptional non-Hermitian topological edge mode and its application to\n  active matter: Topological materials exhibit edge-localized scattering-free modes protected\nby their nontrivial bulk topology through the bulk-edge correspondence in\nHermitian systems. While topological phenomena have recently been much\ninvestigated in non-Hermitian systems with dissipations and injections, the\nfundamental principle of their edge modes has not fully been established. Here,\nwe reveal that in non-Hermitian systems robust gapless edge modes can\nubiquitously appear owing to a mechanism that is distinct from bulk topology,\nthus indicating the breakdown of the bulk-edge correspondence. The robustness\nof these edge modes originates from yet another topological structure\naccompanying the branchpoint singularity around an exceptional point, at which\neigenvectors coalesce and the Hamiltonian becomes nondiagonalizable. Their\ncharacteristic complex eigenenergy spectra are applicable to realize lasing\nwave packets that propagate along the edge of the sample. We numerically\nconfirm the emergence and the robustness of the proposed edge modes in the\nprototypical models. Furthermore, we show that these edge modes appear in a\nmodel of chiral active matter based on the hydrodynamic description,\ndemonstrating that active matter can exhibit an inherently non-Hermitian\ntopological feature. The proposed general mechanism would serve as an\nalternative designing principle to realize scattering-free edge current in\nnon-Hermitian devices, going beyond the existing frameworks of non-Hermitian\ntopological phases."
    },
    {
        "anchor": "Plasmons in a Superlattice of Fullerenes or Metallic Shells: A theory for the collective plasma excitations in a linear periodic array of\nspherical two-dimensional electron gases (S2DEGs) is presented. This is a\nsimple model for an ultra thin and narrow microribbon of fullerenes or metallic\nshells. Coulomb coupling between electrons located on the same sphere and on\ndifferent spheres is included in the random-phase approximation (RPA). Electron\nhopping between spheres is neglected in these calculations. The resulting\nplasmon-dispersion equation is solved numerically. Results are presented for a\nsuperlattice of single-wall S2DEGs as a function of the wave vector. The\nplasmon dispersions are obtained for different spherical separations. We show\nthat the one-dimensional translational symmetry of the lattice is maintained in\nthe plasmon spectrum. Additionally, we compare the plasmon dispersion when the\nsuperlatice direction is parallel or perpendicular to the axis of quantization.\nHowever, because of anisotropy in the Coulomb matrix elements, there is\nanticrossing in the plasmon dispersion only in the direction perpendicular to\nthe quantization axis. The S2DEG may serve as a simple model for fullerenes,\nwhen their energy bands are far apart.",
        "positive": "Charge and heat transport of soft nanosystems in the presence of\n  time-dependent perturbations: Soft nanosystems are electronic nanodevices, such as suspended carbon\nnanotubes or molecular junctions, whose transport properties are modulated by\nsoft internal degrees of freedom, for example slow vibrational modes. In this\nreview, effects of the electron-vibration coupling on the charge and heat\ntransport of soft nanoscopic systems are theoretically investigated in the\npresence of time-dependent perturbations, such as a forcing antenna or pumping\nterms between the leads and the nanosystem. A well established approach valid\nfor non-equilibrium adiabatic regimes is generalized to the case where external\ntime-dependent perturbations are present. Then, a number of relevant\napplications of the method are reviewed for systems composed by a quantum dot\n(or molecule) described by a single electronic level coupled to a vibrational\nmode. Before introducing time-dependent perturbations, the range of validity of\nthe adiabatic approach is discussed showing that a very good agreement with the\nresults of an exact quantum calculation is obtained in the limit of low level\noccupation. Aim of this review has been to discuss common features of different\nsoft nanosystems under external drive. The most interesting effects induced by\ntime-dependent perturbations are obtained when the external forcing is nearly\nresonant with the slow vibrational modes. Indeed, not only the external forcing\ncan enhance the electronic response, but it also induces nonlinear regimes\nwhere the interplay between electronic and vibrational degrees of freedom plays\na major role."
    },
    {
        "anchor": "Visualizing Encapsulated Graphene, its Defects and its Charge\n  Environment by Sub-Micrometer Resolution Electrical Imaging: Devices made from two-dimensional (2D) materials such as graphene or\ntransition metal dichalcogenides possess interesting electronic properties that\ncan become accessible to experimental probes when the samples are protected\nfrom deleterious environmental effects by encapsulating them between hexagonal\nboron nitride (hBN) layers. While the encapsulated flakes can be detected\nthrough post-processing of optical images or confocal Raman mapping, these\ntechniques lack the sub-micrometer scale resolution to identify tears,\nstructural defects or impurities, which is crucial for the fabrication of\nhigh-quality devices. Here we demonstrate a simple method to visualize such\nburied flakes with sub-micrometer resolution, by combining Kelvin force probe\nmicroscopy (KPFM) with electrostatic force microscopy (EFM). KPFM, which\nmeasures surface potential fluctuations, is extremely effective in spotting\ncharged contaminants within and on top of the heterostructure, making it\npossible to distinguish contaminated regions in the buried flake. When applying\na tip bias larger than the surface potential fluctuations, EFM becomes\nextremely efficient in highlighting encapsulated flakes and their sub-micron\nstructural defects. We show that these imaging modes, which are standard\nextensions of atomic force microscopy (AFM), are perfectly suited for locating\nencapsulated conductors, for visualizing nanometer scale defects and bubbles,\nand for characterizing their local charge environment.",
        "positive": "Valley-polarized quantum anomalous Hall phase and disorder induced\n  valley-filtered chiral edge channels: We investigate the topological and transport properties of the recently\ndiscovered valley-polarized quantum anomalous Hall (VQAH) phase. In single\nlayer, the phase is realized through the competition between two types of\nspin-orbit coupling, which breaks the symmetry between the two valleys. We show\nthat the topological phase transition from conventional quantum anomalous Hall\nphase to the VQAH phase is due to the change of topological charges with the\ngeneration of additional skyrmions in the real spin texture, when the band gap\ncloses and reopens at one of the valleys. In the presence of short range\ndisorders, pairs of the gapless edge channels (one from each valley in a pair)\nwould be destroyed due to intervalley scattering. However, we discover that in\nan extended range of moderate scattering strength, the transport through the\nsystem is quantized and fully valley-polarized, i.e. the system is equivalent\nto a quantum anomalous Hall system with valley-filtered chiral edge channels.\nWe further show that with additional layer degree of freedom, much richer phase\ndiagram could be realized with multiple VQAH phases. For a bilayer system, we\ndemonstrate that topological phase transitions could be controlled by the\ninterlayer bias potential."
    },
    {
        "anchor": "Background charge fluctuation in a GaAs quantum dot device: We investigate background charge fluctuation in a GaAs quantum dot device by\nmeasuring 1/f noise in the single-electron tunneling current through the dot.\nThe current noise is understood as fluctuations of the confinement potential\nand tunneling barriers. The estimated potential fluctuation increases almost\nlinearly with temperature, which is consistent with a simple model of the 1/f\nnoise. We find that the fluctuation increases very slightly when electrons are\ninjected into excited states of the quantum dot.",
        "positive": "Forming 1D Periodic J-aggregates by Mechanical Bending of BNNTs:\n  Evidence of Activated Molecular Diffusion: Driving molecular assembly into micrometer-scale patterns is key for defining\nadvanced materials of interest in various fields, including life sciences,\nphotovoltaics, and quantum photonics. However, the driving process competes\nwith other forces, such as Brownian motion, ripening phenomena, capillary\nforces, and non-specific adsorption. Here we report on a guided diffusion\nmechanism of luminescent dye molecules encapsulated inside boron nitride\nnanotubes (BNNTs). Correlative measurements between BNNT bending and molecular\nposition along the BNNT axis reveal an efficient and long-range migration of\ndyes from curved to straight regions of the nanotube. This curvature activated\ndiffusion forms clusters of bright J-aggregates in periodic patterns of\nwell-defined spacing and length. A phenomenological model of guided molecular\ntransport in bended BNNTs is used to describe this directed 1D diffusion inside\nBNNT. It is shown to accurately predict the position and morphologies of a\nJ-aggregate as a function of nanotube length. Coupling topological stimuli to\n1D molecular diffusion at the nanoscale is here presented as an interesting\ntool capable of reconfiguring various emissive patterns of functional molecules\nat the mesoscopic scale."
    },
    {
        "anchor": "Thermal radiation from optically driven Kerr ($\u03c7^{(3)}$) photonic\n  cavities: We study thermal radiation from nonlinear ($\\chi^{(3)}$) photonic cavities\ncoupled to external channels and subject to incident monochromatic light. Our\nwork extends related work on nonlinear mechanical oscillators [Phys. Rev. Lett.\n97, 110602 (2006)] to the problem of thermal radiation, demonstrating that\nbistability can enhance thermal radiation by orders of magnitude and result in\nstrong lineshape alternations, including \"super-narrow spectral peaks\"\noccurring at the onset of kinetic phase transitions. We show that when the\ncavities are designed so as to have perfect linear absorptivity (rate\nmatching), such thermally activated transitions can be exploited to\ndramatically tune the output power and radiative properties of the cavity,\nleading to a kind of Kerr-mediated thermo-optic effect. Finally, we demonstrate\nthat in certain parameter regimes, the output radiation exhibits Stokes and\nanti-Stokes side peaks whose relative magnitudes can be altered by tuning the\ninternal temperature of the cavity relative to its surroundings, a consequence\nof strong correlations and interference between the emitted and reflected\nradiation.",
        "positive": "Phase Diagram of Integer Quantum Hall Effect: The phase diagram of integer quantum Hall effect is numerically determined in\nthe tight-binding model, which can account for overall features of recently\nobtained experimental phase diagram. In particular, the quantum Hall plateaus\nare terminated by two distinct insulating phases, characterized by the Hall\nresistance with classic and quantized values, respectively, which is also in\ngood agreement with experiments."
    },
    {
        "anchor": "Signatures of spin-preserving symmetries in two-dimensional hole gases: We investigate ramifications of the persistent spin helix symmetry in\ntwo-dimensional hole gases in the conductance of disordered mesoscopic systems.\nTo this end we extend previous models by going beyond the axial approximation\nfor III-V semiconductors. For heavy-hole subbands we identify an exact\nspin-preserving symmetry analogous to the electronic case by analyzing the\ncrossover from weak antilocalization to weak localization and spin transmission\nas a function of extrinsic spin-orbit interaction strength.",
        "positive": "Gate-tunable zero-frequency current cross-correlations of the quartet\n  mode in a voltage-biased three-terminal Josephson junction: A three-terminal Josephson junction biased at opposite voltages can sustain a\nphase-sensitive dc-current carrying three-body static phase coherence, known as\nthe \"quartet current\". We calculate the zero-frequency current noise\ncross-correlations and answer the question of whether this current is noisy\n(like a normal current in response to a voltage drop) or noiseless (like an\nequilibrium supercurrent in response to a phase drop). A quantum dot with a\nlevel at energy $\\epsilon_0$ is connected to three superconductors $S_a$, $S_b$\nand $S_c$ with gap $\\Delta$, biased at $V_a=V$, $V_b=-V$ and $V_c=0$, and with\nintermediate contact transparencies. At zero temperature, nonlocal quartets (in\nthe sense of four-fermion correlations) are noiseless at subgap voltage in the\nnonresonant dot regime $\\epsilon_0/\\Delta\\gg 1$, which is demonstrated with a\nsemi-analytical perturbative expansion of the cross-correlations. Noise reveals\nthe absence of granularity of the superflow splitting from $S_c$ towards\n$(S_a,S_b)$ in the nonresonant dot regime, in spite of finite voltage. In the\nresonant dot regime $\\epsilon_0/\\Delta< 1$, cross-correlations measured in the\n$(V_a,V_b)$ plane should reveal an \"anomaly\" in the vicinity of the quartet\nline $V_a+V_b=0$, related to an additional contribution to the noise,\nmanifesting the phase sensitivity of cross-correlations under the appearance of\na three-body phase variable. Phase-dependent effective Fano factors $F_\\varphi$\nare introduced, defined as the ratio between the amplitudes of phase\nmodulations of the noise and the currents. At low bias, the Fano factors\n$F_\\varphi$ are of order unity in the resonant dot regime $\\epsilon_0/\\Delta<\n1$, and they are vanishingly small in the nonresonant dot regime\n$\\epsilon_0/\\Delta\\gg 1$."
    },
    {
        "anchor": "Fourier Magnetic Imaging with Nanoscale Resolution and Compressed\n  Sensing Speed-up using Electronic Spins in Diamond: Optically-detected magnetic resonance using Nitrogen Vacancy (NV) color\ncentres in diamond is a leading modality for nanoscale magnetic field imaging,\nas it provides single electron spin sensitivity, three-dimensional resolution\nbetter than 1 nm, and applicability to a wide range of physical and biological\nsamples under ambient conditions. To date, however, NV-diamond magnetic imaging\nhas been performed using real space techniques, which are either limited by\noptical diffraction to 250 nm resolution or require slow, point-by-point\nscanning for nanoscale resolution, e.g., using an atomic force microscope,\nmagnetic tip, or super-resolution optical imaging. Here we introduce an\nalternative technique of Fourier magnetic imaging using NV-diamond. In analogy\nwith conventional magnetic resonance imaging (MRI), we employ pulsed magnetic\nfield gradients to phase-encode spatial information on NV electronic spins in\nwavenumber or k-space followed by a fast Fourier transform to yield real-space\nimages with nanoscale resolution, wide field-of-view (FOV), and compressed\nsensing speed-up.",
        "positive": "Asymmetric Double Quantum Wells with Smoothed Interfaces: We have derived and analyzed the wavefunctions and energy states for an\nasymmetric double quantum wells, broadened due to static interface disorder\neffects, within well known discreet variable representation approach for\nsolving the one-dimensional Schrodinger equation. The main advantage of this\napproach is that it yields the energy eigenvalues and the eigenvectors in\nsemiconductor nanostructures of different shapes as well as the strengths of\nthe optical transitions between them. We have found that interface broadening\neffects change and shift energy levels to higher energies, but the resonant\nconditions near an energy coupling regions do not strongly distorted. A\nquantum-mechanical calculations based on the convolution method (smoothing\nprocedure) of the influence of disorder on the motion of free particles in\nnanostructures is presented."
    },
    {
        "anchor": "Spin-valley dependent double Andreev reflections in the proximitized\n  graphene/superconductor junction: We study the Andreev reflections and the quantum transport in the\nproximitized graphene/superconductor junction. The proximitized graphene\npossesses the pseudospin staggered potential and the intrinsic spin-orbit\ncoupling induced by substrate, which are responsible for the spin-valley\ndependent double Andreev reflections and the anomalous transport properties in\nthe junction. The pure specular Andreev reflection can happen in the\nsuperconducting gap for the $K\\uparrow$ and $K'\\downarrow$ electrons while the\npure retro-Andreev reflection happens for the $K\\downarrow$ and $K'\\uparrow$\nelectrons. The coexisting two types of Andreev reflections related to the fixed\nspin-valley indices strongly depend on the chemical potential of the\nproximitized graphene. The condition of the emergence of the specific type of\nAndreev reflection for the electrons with the fixed spin-valley index is\nclarified. The spin-valley dependent Andreev reflections bring about the\npeculiar conductance spectra of the junction, which can help determine the\nvalues of the pseudospin staggered potential and the intrinsic spin-orbit\ncoupling induced in graphene. Hence, our research results not only provide an\nexperimental method to detect the induced potential and coupling in graphene\nbut also establish the foundation of the superconductor electronics based on\nthe spin-valley indices.",
        "positive": "Wearing a single DNA molecule with an AFM tip: While the fundamental limit on the resolution achieved in an atomic force\nmicroscope (AFM) is clearly related to the tip radius, the fact that the tip\ncan creep and/or wear during an experiment is often ignored. This is mainly due\nto the difficulty in characterizing the tip, and in particular a lack of\nreliable methods that can achieve this in situ. Here, we provide an in situ\nmethod to characterize the tip radius and monitor tip creep and/or wear and\nbiomolecular sample wear in ambient dynamic AFM. This is achieved by monitoring\nthe dynamics of the cantilever and the critical free amplitude to observe a\nswitch from the attractive to the repulsive regime. The method is exemplified\non the mechanically heterogeneous sample of single DNA molecules bound to mica\nmineral surfaces. Simultaneous monitoring of apparent height and width of\nsingle DNA molecules while detecting variations in the tip radius R as small as\none nanometer are demonstrated. The yield stress can be readily exceeded for\nsharp tips (R<10 nm) at typical operating amplitudes (A>10nm). The ability to\nknow the AFM tip radius in situ and in real-time opens up the future for\nquantitative nanoscale materials properties determination at the highest\npossible spatial resolution."
    },
    {
        "anchor": "Regenerative Soot-V: Spectroscopy of the regenerative sooting discharges: The mechanisms and processes of the formation of the regenerative soot in a\ngraphite hollow cathode discharge that produces and emits carbon clusters are\npresented. Mass spectrometry with a designed ExB velocity filter analyzes the\nentire range of the charged clusters from monatomic Carbon C1 to as large\nclusters as C4300. The state of the carbon vapor within the source is evaluated\nby using the characteristic line emissions from the carbonaceous discharge\nwhose formative mechanisms depend upon the kinetic and potential sputtering of\nthe sooted cathode. The carbonaceous discharge generates atomic and ionic C and\nits clusters Cm where m is equal to or greater than 2, noble gas metastable\natoms and ions, energetic electrons and photons in the cavity of the graphite\nhollow cathode. The parameters of soot formation and its recycling depend\ncritically on the discharge parameters, the geometry of the hollow cathode and\n3D profile of the cusp magnetic field contours.",
        "positive": "Effects of magnetic field and transverse anisotropy on full counting\n  statistics in single-molecule magnet: We have theoretically studied the full counting statistics of electron\ntransport through a single-molecule magnet (SMM) with an arbitrary angle\nbetween the applied magnetic field and the SMM's easy axis above the sequential\ntunneling threshold, since the angle $\\theta$ cannot be controlled in\npresent-day SMM experiments. In the absence of the small transverse anisotropy,\nwhen the coupling of the SMM with the incident-electrode is stronger than that\nwith the outgoing-electrode, i.e., $\\Gamma_{L}/\\Gamma_{R}\\gg1$, the maximum\npeak of shot noise first increases and then decreases with increasing $\\theta$\nfrom 0 to $0.5\\pi$. In particular, the shot noise can reach up to\nsuper-Poissonian value from sub-Poissonian value when considering the small\ntransverse anisotropy. For $\\Gamma_{L}/\\Gamma_{R}\\ll1$, the maximum peaks of\nthe shot noise and skewness can be reduced from a super-Poissonian to a\nsub-Poissonian value with increasing $\\theta$ from 0 to $0.5\\pi$; the\nsuper-Poissonian behavior of the skewness is more sensitive to the small\n$\\theta$ than shot noise, which is suppressed when taking into account the\nsmall transverse anisotropy. These characteristics of shot noise can be\nqualitatively attributed to the competition between the fast and slow transport\nchannels. The predictions regarding of the $\\theta$-dependence of high order\ncurrent cumulants are very interesting for a better understanding electron\ntransport through SMM, and will allow for experimental tests in the near\nfuture."
    },
    {
        "anchor": "Topological Triviality of Flat Hamiltonians: Landau levels play a key role in theoretical models of the quantum Hall\neffect. Each Landau level is degenerate, flat and topologically non-trivial.\nMotivated by Landau levels, we study tight-binding Hamiltonians whose energy\nlevels are all flat. We demonstrate that in two dimensions, for such\nHamiltonians, the flat bands must be topologically trivial. To that end, we\nshow that the projector onto each flat band is necessarily strictly local. Our\nconclusions do not need the assumption of lattice translational invariance.",
        "positive": "Geometric phases of Topological Systems under Quench Process: We study the time evolution of geometric phases of one dimensional\ntopological models under the quench dynamics. Taking the Creutz ladder model as\nan example, it is found that the Berry phase is fixed as the parameter is\nsuddenly tuned across the topological phase boundary, given that the chiral\nsymmetry of the model is preserved. At finite temperature, the Uhlmann phase\ndisplays abrupt jumps between the two quantized values, which indicates the\ntopological transition at certain times after the quench. Both the Berry and\nUhlmann phase will deviate from quantized values if the chiral symmetry of the\nmodel is broken. The relation between the Uhlmann phase and Loshmidt rate\nfunction under the quench process is also discussed."
    },
    {
        "anchor": "Spin effects in single-electron tunneling in magnetic junctions: Spin dependent single electron tunneling in ferromagnetic double junctions is\nanalysed theoretically in the limit of sequential tunneling. The influence of\ndiscrete energy spectrum of the central electrode (island)on the spin\naccumulation, spin fluctuations and tunnel magnetoresistance is analysed\nnumerically in the case of a nonmagnetic island. It is shown that spin\nfluctuations are significant in magnetic as well as in nonmagnetic junctions.",
        "positive": "Robust band gap and half-metallicity in graphene with triangular\n  perforations: Ideal graphene antidot lattices are predicted to show promising band gap\nbehavior (i.e., $E_G\\simeq 500$ meV) under carefully specified conditions.\nHowever, for the structures studied so far this behavior is critically\ndependent on superlattice geometry and is not robust against experimentally\nrealistic disorders. Here we study a rectangular array of triangular antidots\nwith zigzag edge geometries and show that their band gap behavior qualitatively\ndiffers from the standard behavior which is exhibited, e.g, by rectangular\narrays of armchair-edged triangles. In the spin unpolarized case, zigzag-edged\nantidots give rise to large band gaps compared to armchair-edged antidots,\nirrespective of the rules which govern the existence of gaps in armchair-edged\nantidot lattices. In addition the zigzag-edged antidots appear more robust than\narmchair-edged antidots in the presence of geometrical disorder. The inclusion\nof spin polarization within a mean-field Hubbard approach gives rise to a large\noverall magnetic moment at each antidot due to the sublattice imbalance imposed\nby the triangular geometry. Half-metallic behavior arises from the formation of\nspin-split dispersive states near the Fermi energy, reducing the band gaps\ncompared to the unpolarized case. This behavior is also found to be robust in\nthe presence of disorder. Our results highlight the possibilities of using\ntriangular perforations in graphene to open electronic band gaps in systems\nwith experimentally realistic levels of disorder, and furthermore, of\nexploiting the strong spin dependence of the system for spintronic\napplications."
    },
    {
        "anchor": "Water-assisted electronic transport in graphene nanogaps for DNA\n  sequencing: Innovative methodologies for reliably and inexpensively sequencing DNA can\nlead to a new era of personalized medicine. In this work, we performed a\ntheoretical investigation of a nanogap-based all electronic DNA sequencing\ndevice. To do so, we used a nitrogen-terminated nanogap on a graphene sheet\nwith the environment fully taken into account. Our investigation is performed\nusing a hybrid methodology combining quantum and classical mechanics coupled to\nnon-equilibrium Green's functions for solving the electron transport across the\ndevice. The obtained results show that the DNA nucleotides can be both detected\nand distinguished in such device, which indicates that it can be used as a DNA\nsequencing device providing very high sensitivity and selectivity. Furthermore,\nour results show that water plays a major role in electronic transport in\nnanoscopic tunneling devices, not only from an electrostatics point of view,\nbut also by providing states that significantly increase the conductance in\nnanogap-based DNA sequencing devices.",
        "positive": "Unravelling the intrinsic and robust nature of van Hove singularities in\n  twisted bilayer graphene: Extensive scanning tunnelling microscopy and spectroscopy experiments\ncomplemented by first principles and parameterized tight binding calculations\nprovide a clear answer to the existence, origin and robustness of van Hove\nsingularities (vHs) in twisted graphene layers. Our results are conclusive: vHs\ndue to interlayer coupling are ubiquitously present in a broad range (from\n1{\\deg} to 10{\\deg}) of rotation angles in our graphene on 6H-SiC(000-1)\nsamples. From the variation of the energy separation of the vHs with rotation\nangle we are able to recover the Fermi velocity of a graphene monolayer as well\nas the strength of the interlayer interaction. The robustness of the vHs is\nassessed both by experiments, which show that they survive in the presence of a\nthird graphene layer, and calculations, which test the role of the periodic\nmodulation and absolute value of the interlayer distance. Finally, we clarify\nthe origin of the related moir\\'e corrugation detected in the STM images."
    },
    {
        "anchor": "Dynamical current-induced ferromagnetic and antiferromagnetic resonances: We demonstrate that ferromagnetic and antiferromagnetic excitations can be\ntriggered by the dynamical spin accumulations induced by the bulk and surface\ncontributions of the spin Hall effect. Due to the spin-orbit interaction, a\ntime-dependent spin density is generated by an oscillatory electric field\napplied parallel to the atomic planes of Fe/W(110) multilayers. For symmetric\ntrilayers of Fe/W/Fe in which the Fe layers are ferromagnetically coupled, we\ndemonstrate that only the collective out-of-phase precession mode is excited,\nwhile the uniform (in-phase) mode remains silent. When they are\nantiferromagnetically coupled, the oscillatory electric field sets the Fe\nmagnetizations into elliptical precession motions with opposite angular\nvelocities. The manipulation of different collective spin-wave dynamical modes\nthrough the engineering of the multilayers and their thicknesses may be used to\ndevelop ultrafast spintronics devices. Our work provides a general framework\nthat probes the realistic responses of materials in the time or frequency\ndomain.",
        "positive": "One-loop omega-potential of quantum fields with ellipsoid\n  constant-energy surface dispersion law: Rapidly convergent expansions of a one-loop contribution to the partition\nfunction of quantum fields with ellipsoid constant-energy surface dispersion\nlaw are derived. The omega-potential is naturally decomposed into three parts:\nthe quasiclassical contribution, the contribution from the branch cut of the\ndispersion law, and the oscillating part. The low- and high-temperature\nexpansions of the quasiclassical part are obtained. An explicit expression and\na relation of the contribution from the cut with the Casimir term and vacuum\nenergy are established. The oscillating part is represented in the form of the\nChowla-Selberg expansion for the Epstein zeta function. Various resummations of\nthis expansion are considered. The developed general procedure is applied to\ntwo models: massless particles in a box both at zero and non-zero chemical\npotential; electrons in a thin metal film. The rapidly convergent expansions of\nthe partition function and average particle number are obtained for these\nmodels. In particular, the oscillations of the chemical potential of conduction\nelectrons in graphene and a thin metal film due to a variation of sizes of the\ncrystal are described."
    },
    {
        "anchor": "Gate induced enhancement of spin-orbit coupling in dilute fluorinated\n  graphene: We analyze the origin of spin-orbit coupling (SOC) in fluorinated graphene\nusing Density Functional Theory (DFT) and a tight-binding model for the\nrelevant orbitals. As it turns out, the dominant source of SOC is the atomic\nspin-orbit of fluorine adatoms and not the impurity induced SOC based on the\ndistortion of the graphene plane as in hydrogenated graphene. More\ninterestingly, our DFT calculations show that SOC is strongly affected by both\nthe type and concentrations of the graphene's carriers, being enhanced by\nelectron doping and reduced by hole doping. This effect is due to the charge\ntransfer to the fluorine adatom and the consequent change in the\nfluorine-carbon bonding. Our simple tight-binding model, that includes the SOC\nof the $2p$ orbitals of F and effective parameters based on maximally localized\nWannier functions, is able to account for the effect. The strong enhancement of\nthe SOC induced by graphene doping opens the possibility to tune the spin\nrelaxation in this material.",
        "positive": "Network architecture of energy landscapes in mesoscopic quantum systems: Mesoscopic quantum systems exhibit complex many-body quantum phenomena, where\ninteractions between spins and charges give rise to collective modes and\ntopological states. Even simple, non-interacting theories display a rich\nlandscape of energy states --- distinct many-particle configurations connected\nby spin- and energy-dependent transition rates. The collective energy landscape\nis difficult to characterize or predict, especially in regimes of frustration\nwhere many-body effects create a multiply degenerate landscape. Here we use\nnetwork science to characterize the complex interconnection patterns of these\nenergy-state transitions. Using an experimentally verified computational model\nof electronic transport through quantum antidots, we construct networks where\nnodes represent accessible energy states and edges represent allowed\ntransitions. We then explore how physical changes in currents and voltages are\nreflected in the network topology. We find that the networks exhibit Rentian\nscaling, which is characteristic of efficient transportation systems in\ncomputer circuitry, neural circuitry, and human mobility, and can be used to\nmeasure the interconnection complexity of a network. Remarkably, networks\ncorresponding to points of frustration in quantum transport (due, for example,\nto spin-blockade effects) exhibit an enhanced topological complexity relative\nto networks not experiencing frustration. Our results demonstrate that network\ncharacterizations of the abstract topological structure of energy landscapes\ncan capture salient properties of quantum transport. More broadly, our approach\nmotivates future efforts to use network science in understanding the dynamics\nand control of complex quantum systems."
    },
    {
        "anchor": "Trends in the hyperfine interactions of magnetic adatoms on thin\n  insulating layers: Nuclear spins are among the potential candidates prospected for quantum\ninformation technology. A recent breakthrough enabled to atomically resolve\ntheir interaction with the electron spin, the so-called hyperfine interaction,\nwithin individual atoms utilizing scanning tunneling microscopy (STM).\nIntriguingly, this was only realized for a few species put on a two-layers\nthick MgO. Here, we systematically quantify from first-principles the hyperfine\ninteractions of the whole series of 3d transition adatoms deposited on various\nthicknesses of MgO, NaF, NaCl, h--BN and Cu$_2$N films. We identify the\nadatom-substrate complexes with the largest hyperfine interactions and unveil\nthe main trends and exceptions. We reveal the core mechanisms at play, such as\nthe interplay of the local bonding geometry and the chemical nature of the thin\nfilms, which trigger transitions between high- and low-spin states accompanied\nwith subtle internal rearrangements of the magnetic electrons. By providing a\ngeneral map of hyperfine interactions, our work has immediate implications in\nfuture STM investigations aiming at detecting and realizing quantum concepts\nhinging on nuclear spins.",
        "positive": "Numbers of donors and acceptors from transport measurements in graphene: A method is suggested to separately determine the surface density of\npositively and negatively charged impurities that limit the mobility in a\ngraphene monolayer. The method is based on the exact result for the transport\ncross-section, according to which the massless carriers are scattered more\nstrongly when they are attracted to a charged impurity than when they are\nrepelled from it."
    },
    {
        "anchor": "Renormalized Landau Levels and Particle-Hole Symmetry in Graphene: In this proceedings paper we report on a calculation of graphene's Landau\nlevels in a magnetic field. Our calculations are based on a self-consistent\nHartree-Fock approximation for graphene's massless-Dirac continuum model. We\nfind that because of graphene's chiral band structure interactions not only\nshift Landau-level energies, as in a non-relativistic electron gas, but also\nalter Landau level wavefunctions. We comment on the subtle continuum model\nregularization procedure necessary to correctly maintain the lattice-model's\nparticle hole symmetry properties.",
        "positive": "Kinetic derivation of generalized phase space Chern-Simons theory: We study anomalous transport phenomena induced by phase-space Berry\ncurvature. For that purpose we construct a kinetic theory in $2d$ phase space\nwhen all abelian Berry curvatures are nonzero. We derive anomalous currents by\ncalculating the complete form of the Poisson brackets of phase space\ncoordinates. Then we construct the low-energy effective theory to reproduce the\nanomalous currents obtained from the kinetic theory. Such an effective theory\nis given by the Chern-Simons theory in $1+2d$ dimensions. Some implications of\nthe Chern-Simons theory are also discussed."
    },
    {
        "anchor": "Avoided level crossing at the magnetic field induced topological phase\n  transition due to spin-orbital mixing: In 3D topological insulators, an effective closure of the bulk energy gap\nwith increasing magnetic field expected at a critical point can yield a band\ncrossing at a gapless Dirac node. Using high-field magnetooptical Landau level\nspectroscopy on the topological crystalline insulator Pb1-xSnxSe, we\ndemonstrate that such a gap closure does not occur, and an avoided crossing is\nobserved as the magnetic field is swept through the critical field. We\nattribute this anticrossing to orbital parity and spin mixing of the N=0\nlevels. Concurrently, we observe no gap closure at the topological phase\ntransition versus temperature suggesting that the anticrossing is a generic\nproperty of topological phase transitions.",
        "positive": "Missing odd-order Shapiro steps do not uniquely indicate fractional\n  Josephson effect: Topological superconductivity is expected to spur Majorana zero modes --\nexotic states that are also considered a quantum technology asset. Fractional\nJosephson effect is their manifestation in electronic transport measurements,\noften under microwave irradiation. A fraction of induced resonances, known as\nShapiro steps, should vanish, in a pattern that signifies the presence of\nMajorana modes. Here we report patterns of Shapiro steps expected in\ntopological Josephson junctions, such as the missing first Shapiro step, or\nseveral missing odd-order steps. But our junctions, which are InAs quantum\nwells with Al contacts, are studied near zero magnetic field, meaning that they\nare not in the topological regime. We also observe other patterns such as\nmissing even steps and several missing steps in a row, not relevant to\ntopological superconductivity. Potentially responsible for our observations is\nrounding of not fully developed steps superimposed on non-monotonic resistance\nversus voltage curves, but several origins may be at play. Our results\ndemonstrate that any single pattern, even striking, cannot uniquely identify\ntopological superconductivity, and a multifactor approach is necessary to\nunambiguously establish this important phenomenon."
    },
    {
        "anchor": "Quantum Irreversibility of Energy Spreading: The analysis of dissipation and dephasing in driven mesoscopic devices\nrequires a distinction between two notions of quantum irreversibility. One\n(\"Loschmidt echo\") is related to \"time reversal\", while the other is related to\n\"driving reversal\". In the latter context the time of maximum return\n(compensation) should substitute the inappropriate notion of \"echo\" time.\nNon-perturbative features manifest themselves in the energy spreading process.\nThis is demonstrated for the prototype random-matrix Wigner model, where the\ncompensation time and the system response exhibit a non-universal scaling\nbehavior.",
        "positive": "Massive Dirac Fermions Signal in Raman Spectrum of Graphene: Massless Dirac fermions in graphene can acquire a mass through different\nkinds of sublattice-symmetry-breaking perturbations, and there is a growing\nneed to determine this mass using a conventional method. We describe how the\nmass caused by a staggered sublattice potential is determined using Raman\nspectroscopy and explain the mechanism in terms of the pseudospin polarization\nof massive Dirac fermions."
    },
    {
        "anchor": "Two-orbital effective model for magnetic Weyl semimetal in\n  Kagome-lattice shandite: We construct a two-orbital effective model for a ferromagnetic Kagome-lattice\nshandite, $\\rm{{Co}_3{Sn}_2{S}_2}$, a candidate material of magnetic Weyl\nsemimetals, by considering one $d$ orbital from Co, and one $p$ orbital from\ninterlayer Sn. The energy spectrum near the Fermi level, and the configurations\nof the Weyl points, computed by using our model, are similar to those obtained\nby first principle calculations. We show also that nodal rings appear even with\nspin-orbit coupling when the magnetization points in-plane direction.\nAdditionally, magnetic properties of $\\rm{{Co}_3{Sn}_2{S}_2}$ and other\nshandite materials are discussed.",
        "positive": "Random matrices and quantum chaos in weakly-disordered graphene\n  nanoflakes: Statistical distribution of energy levels for Dirac fermions confined in a\nquantum dot is studied numerically on the examples of triangular and hexagonal\ngraphene flakes with random electrostatic potential landscape. When increasing\nthe disorder strength, level distribution evolves from Poissonian to Wigner,\nindicating the transition to quantum chaos. The unitary ensemble (with the\ntwofold valley degeneracy) is observed for triangular flakes with zigzag or\nKlein edges and potential varying smoothly on the scale of atomic separation.\nFor small number of edge defects, the unitary-to-orthogonal symmetry transition\nis found at zero magnetic field. For remaining systems, the orthogonal ensemble\nappears. These findings are rationalized by means of additive random-matrix\nmodels for the cases of weak and strong intervalley scattering of charge\ncarriers in graphene. The influence of weak magnetic fields, as well as the\nstrong-disorder-induced wavefunction localization, on the level distribution is\nalso briefly discussed."
    },
    {
        "anchor": "Gate-Defined Quantum Confinement in InSe-based van der Waals\n  Heterostructures: Indium selenide, a post-transition metal chalcogenide, is a novel\ntwo-dimensional (2D) semiconductor with interesting electronic properties. Its\ntunable band gap and high electron mobility have already attracted considerable\nresearch interest. Here we demonstrate strong quantum confinement and\nmanipulation of single electrons in devices made from few-layer crystals of\nInSe using electrostatic gating. We report on gate-controlled quantum dots in\nthe Coulomb blockade regime as well as one-dimensional quantization in point\ncontacts, revealing multiple plateaus. The work represents an important\nmilestone in the development of quality devices based on 2D materials and makes\nInSe a prime candidate for relevant electronic and optoelectronic applications.",
        "positive": "Generating entangled quantum microwaves in a Josephson-photonics device: When connecting a voltage-biased Josephson junction in series to several\nmicrowave cavities, a Cooper-pair current across the junction gives rise to a\ncontinuous emission of strongly correlated photons into the cavity modes.\nTuning the bias voltage to the resonance where a single Cooper pair provides\nthe energy to create an additional photon in each of the cavities, we\ndemonstrate the entangling nature of these creation processes by simple\nwitnesses in terms of experimentally accessible observables. To characterize\nthe entanglement properties of the such created quantum states of light to the\nfullest possible extent, we then proceed to more elaborate entanglement\ncriteria based on the knowledge of the full density matrix and provide a\ndetailed study of bi- and multipartite entanglement. In particular, we\nillustrate how due to the relatively simple design of these circuits changes of\nexperimental parameters allow one to access a wide variety of entangled states\ndiffering, e.g., in the number of entangled parties or the dimension of state\nspace. Such devices, besides their promising potential to act as a highly\nversatile source of entangled quantum microwaves, may thus represent an\nexcellent natural testbed for classification and quantification schemes\ndeveloped in quantum information theory."
    },
    {
        "anchor": "Simulation of Schottky-Barrier Phosphorene Transistors: Schottky barrier field-effect transistors (SBFETs) based on few and mono\nlayer phosphorene are simulated by the non-equilibrium Green's function\nformalism. It is shown that scaling down the gate oxide thickness results in\npronounced ambipolar I-V characteristics and significant increase of the\nminimal leakage current. The problem of leakage is especially severe when the\ngate insulator is thin and the number of layer is large, but can be effectively\nsuppressed by reducing phosphorene to mono or bilayer. Different from\ntwo-dimensional graphene and layered dichalcogenide materials, both the\nON-current of the phosphorene SBFETs and the metal-semiconductor contact\nresistance between metal and phosphorene strongly depend on the transport\ncrystalline direction.",
        "positive": "Vortices in Ginzburg-Landau billiards: We present an analysis of the Ginzburg-Landau equations for the description\nof a two-dimensional superconductor in a bounded domain. Using the properties\nof a special integrability point of these equations which allows vortex\nsolutions, we obtain a closed expression for the energy of the superconductor.\n  The role of the boundary of the system is to provide a selection mechanism\nfor the number of vortices.\n  A geometrical interpretation of these results is presented and they are\napplied to the analysis of the magnetization recently measured on small\nsuperconducting disks. Problems related to the interaction and nucleation of\nvortices are discussed."
    },
    {
        "anchor": "Large spin-orbit coupling in carbon nanotubes: It has recently been recognized that the strong spin-orbit interaction\npresent in solids can lead to new phenomena, such as materials with non-trivial\ntopological order. Although the atomic spin-orbit coupling in carbon is weak,\nthe spin-orbit coupling in carbon nanotubes can be significant due to their\ncurved surface. Previous works have reported spin-orbit couplings in reasonable\nagreement with theory, and this coupling strength has formed the basis of a\nlarge number of theoretical proposals. Here we report a spin-orbit coupling in\nthree carbon nanotube devices that is an order of magnitude larger than\nmeasured before. We find a zero-field spin splitting of up to 3.4 meV,\ncorresponding to a built-in effective magnetic field of 29 T aligned along the\nnanotube axis. While the origin of the large spin-orbit coupling is not\nexplained by existing theories, its strength is promising for applications of\nthe spin-orbit interaction in carbon nanotubes devices.",
        "positive": "Size Effect in Electron Paramagnetic Resonance Spectra of Impurity\n  Centers in Diamond Nanoparticles: The evolution of the polycrystalline pattern of electron paramagnetic\nresonance (EPR) spectra of intrinsic and induced paramagnetic centers in an\nensemble of submicrometer diamond particles on diminishing average particle\nsize is considered. Recent experimental data unambiguously demonstrate\nconsistent reduction and then zeroing of typical hyperfine pattern from P1\ncenters on approaching a certain particle size and below it. These changes are\naccompanied by appearance and strengthening of new structureless signals. In\nsmall particles the electron wave function of a surface paramagnetic center is\ndelocalized over the whole nanoparticle. In result the electron spin\n\"experiences\" the average field of all surrounding nuclei, which is zero. At\nthe same time, the paramagnetic centers localized in the bulk of a nanoparticle\nare also cut off the hyperfine interaction due to the electron spin diffusion.\nThus, upon the nanodiamond particle size decreases the hyperfine related\nfeatures of the polycrystalline EPR spectrum become weaker and the spectrum\nappear to be structureless."
    },
    {
        "anchor": "Numerical Studies of Quantum Hall Ferromagnetism in Two-Subband Systems: We carry out a numerical study of the quantum Hall ferromagnetism in a\ntwo-subband system using a set of experimental parameters in a recently\nexperiment [X. C. Zhang, I. Martin, and H. W. Jiang, Phys. Rev. B \\textbf{74},\n073301 (2006)]. Employing the self-consistence local density approximation for\ngrowth direction wave function and the Hartree-Fock theory for the pseudospin\nanisotropy energy, we are able to account for the easy-axis and easy-plane\nquantum Hall ferromagnetism observed at total filling factor $\\nu = 3$ and\n$\\nu= 4$, respectively. Our study provides some insight of how the anisotropy\nenergy, which highly depends upon the distribution of growth direction wave\nfunctions, determines the symmetry of the quantum Hall ferromagnets.",
        "positive": "Chiral-phonon-induced current in helical crystals: In this study, we theoretically show that in a helical crystal, a current is\ninduced by chiral phonons representing the microscopic local rotation of atoms.\nBy treating the rotational motion as a perturbation, we calculate the\ntime-dependent current by using the adiabatic Berry phase method. The time\naverage of the current along the helical axis becomes finite in the metallic\nphase but it vanishes in the insulating phase. On the other hand, the current\nin the hexagonal plane changes with time, but its time average vanishes due to\nthe threefold rotation space-time symmetry. We show that the time evolutions of\nthe current follow the space-time symmetries of the helical systems. Moreover,\nwe explain the reason for the vanishing of the time average of the current in\nthe insulating phase from the aspect of the Chern number in the parameter\nspace."
    },
    {
        "anchor": "Superluminal Tachyonlike Excitations of Dirac Fermions in a Topological\n  Insulator Junction: We have considered a system of two topological insulators and have determined\nthe properties of the surface states at the junction. Here we report that these\nstates, under certain conditions exhibit superluminous (tachyonic) dispersion\nof the Dirac fermions. Although superluminal excitations are known to exist in\noptical systems, this is the first demonstration of possible tachyonic\nexcitations in a purely electronic system. The first ever signature of tachyons\ncould therefore be found experimentally in a topological insulator junction.",
        "positive": "Wetting and Strain Engineering of 2D Materials on Nanopatterned\n  Substrates: The fascinating realm of strain engineering and wetting transitions in\ntwo-dimensional (2D) materials takes place when placed on a two-dimensional\narray of nanopillars or one-dimensional rectangular grated substrates. Our\ninvestigation encompasses a diverse set of atomically thin 2D materials,\nincluding transition metal dichalcogenides, hexagonal boron nitride, and\ngraphene, with a keen focus on the impact of van der Waals adhesion energies to\nthe substrate on the wetting/dewetting behavior on nanopatterned substrates. We\nfind a critical aspect ratio of the nanopillar or grating heights to the period\nof the pattern when the wetting/dewetting transition occurs. Furthermore,\nenergy hysteresis analysis reveals dynamic detachment and re-engagement events\nduring height adjustments, shedding light on energy barriers of 2D monolayer\ntransferred on patterned substrates. Our findings offer avenues for strain\nengineering in 2D materials, leading to promising prospects for future\ntechnological applications."
    },
    {
        "anchor": "Transport in three-dimensional topological insulators: theory and\n  experiment: This article reviews recent theoretical and experimental work on transport\ndue to the surface states of three-dimensional topological insulators. The\ntheoretical focus is on longitudinal transport in the presence of an electric\nfield, including Boltzmann transport, quantum corrections and weak\nlocalization, as well as longitudinal and Hall transport in the presence of\nboth electric and magnetic fields and/or magnetizations. Special attention is\npaid to transport at finite doping, to the $\\pi$-Berry phase, which leads to\nthe absence of backscattering, Klein tunneling and half-quantized Hall\nresponse. Signatures of surface states in ordinary transport and\nmagnetotransport are clearly identified. The review also covers transport\nexperiments of the past years, reviewing the initial obscuring of surface\ntransport by bulk transport, and the way transport due to the surface states\nhas increasingly been identified experimentally. Current and likely future\nexperimental challenges are given prominence and the current status of the\nfield is assessed.",
        "positive": "Anomalous dip observed in intensity autocorrelation function as an\n  inherent nature of single-photon emitters: We report the observation of an anomalous antibunching dip in intensity\nautocorrelation function with photon correlation measurements on a\nsingle-photon emitter (SPE). We show that the anomalous dip observed is a\nmanifestation of quantum nature of SPEs. Taking population dynamics in a\nquantum two-level system into account correctly, we redefine intensity\nautocorrelation function. This is of primary importance for precisely\nevaluating the lowest-level probability of multiphoton generation in SPEs\ntoward realizing versatile pure SPEs for quantum information and communication."
    },
    {
        "anchor": "Symmetry-protected ideal Weyl semimetal in HgTe-class materials: Ideal Weyl semimetals with all Weyl nodes exactly at the Fermi level and no\ncoexisting trivial Fermi surfaces in the bulk, similar to graphene, could\nfeature deep physics such as exotic transport phenomena induced by the chiral\nanomaly. Here, we show that HgTe and half-Heusler compounds, under a broad\nrange of in-plane compressive strain, could be materials in nature realizing\nideal Weyl semimetals with four pairs of Weyl nodes and topological surface\nFermi arcs. Generically, we find that the HgTe-class materials with nontrivial\nband inversion and noncentrosymmetry provide a promising arena to realize ideal\nWeyl semimetals. Such ideal Weyl semimetals could further provide a unique\nplatform to study emergent phenomena such as the interplay between ideal Weyl\nfermions and superconductivity in the half-Heusler compound LaPtBi.",
        "positive": "Explicit gain equations for hybrid graphene-quantum-dot photodetectors: Graphene is an attractive material for broadband photodetection but suffers\nfrom weak light absorption. Coating graphene with quantum dots can\nsignificantly enhance light absorption and create extraordinarily high photo\ngain. This high gain is often explained by the classical gain theory which is\nunfortunately an implicit function and may even be questionable. In this work,\nwe managed to derive explicit gain equations for hybrid graphene-quantum-dot\nphotodetectors. Due to the work function mismatch, lead sulfide (PbS) quantum\ndots coated on graphene will form a surface depletion region near the interface\nof quantum dots and graphene. Light illumination narrows down the surface\ndepletion region, creating a photovoltage that gates the graphene. As a result,\nhigh photo gain in graphene is observed. The explicit gain equations are\nderived from the theoretical gate transfer characteristics of graphene and the\ncorrelation of the photovoltage with the light illumination intensity. The\nderived explicit gain equations fit well with the experimental data, from which\nphysical parameters are extracted."
    },
    {
        "anchor": "Observation of coupling between zero- and two-dimensional semiconductor\n  systems based on anomalous diamagnetic effects: We report the direct observation of coupling between a single self-assembled\nInAs quantum dot and a wetting layer, based on strong diamagnetic shifts of\nmany-body exciton states using magneto-photoluminescence spectroscopy. An\nextremely large positive diamagnetic coefficient is observed when an electron\nin the wetting layer combines with a hole in the quantum dot; the coefficient\nis nearly one order of magnitude larger than that of the exciton states\nconfined in the quantum dots. Recombination of electrons with holes in a\nquantum dot of the coupled system leads to an unusual negative diamagnetic\neffect, which is five times stronger than that in a pure quantum dot system.\nThis effect can be attributed to the expansion of the wavefunction of remaining\nelectrons in the wetting layer or the spread of electrons in the excited states\nof the quantum dot to the wetting layer after recombination. In this case, the\nwavefunction extent of the final states in the quantum dot plane is much larger\nthan that of the initial states because of the absence of holes in the quantum\ndot to attract electrons. The properties of emitted photons that depend on the\nlarge electron wavefunction extents in the wetting layer indicate that the\ncoupling occurs between systems of different dimensionality, which is also\nverified from the results obtained by applying a magnetic field in different\nconfigurations. This study paves a new way to observe hybrid states with zero-\nand two-dimensional structures, which could be useful for investigating the\nKondo physics and implementing spin-based solid-state quantum information\nprocessing.",
        "positive": "Driven Dissipative Majorana Dark Spaces: Pure quantum states can be stabilized in open quantum systems subject to\nexternal driving forces and dissipation by environmental modes. We show that\ndriven dissipative (DD) Majorana devices offer key advantages for stabilizing\ndegenerate state manifolds (`dark spaces') and for manipulating states in dark\nspaces, both with respect to native (non-DD) Majorana devices and to DD\nplatforms with topologically trivial building blocks. For two tunnel-coupled\nMajorana boxes, using otherwise only standard hardware elements (e.g., a noisy\nelectromagnetic environment and quantum dots with driven tunnel links), we\npropose a dark qubit encoding. We anticipate exceptionally high fault tolerance\nlevels due to a conspiracy of DD-based autonomous error correction and\ntopology."
    },
    {
        "anchor": "General Green's function formalism for layered systems: Wave function\n  approach: The single-particle Green's function (GF) of mesoscopic structures plays a\ncentral role in mesoscopic quantum transport. The recursive GF technique is a\nstandard tool to compute this quantity numerically, but it lacks physical\ntransparency and is limited to relatively small systems. Here we present a\nnumerically efficient and physically transparent GF formalism for a general\nlayered structure. In contrast to the recursive GF that directly calculates the\nGF through the Dyson equations, our approach converts the calculation of the GF\nto the generation and subsequent propagation of a scattering wave function\nemanating from a local excitation. This viewpoint not only allows us to\nreproduce existing results in a concise and physically intuitive manner, but\nalso provides analytical expressions of the GF in terms of a generalized\nscattering matrix. This identifies the contributions from each individual\nscattering channel to the GF and hence allows this information to be extracted\nquantitatively from dual-probe STM experiments. The simplicity and physical\ntransparency of the formalism further allows us to treat the multiple\nreflection analytically and derive an analytical rule to construct the GF of a\ngeneral layered system. This could significantly reduce the computational time\nand enable quantum transport calculations for large samples. We apply this\nformalism to perform both analytical analysis and numerical simulation for the\ntwo-dimensional conductance map of a realistic graphene p-n junction. The\nresults demonstrate the possibility of observing the spatially-resolved\ninterference pattern caused by negative refraction and further reveal a few\ninteresting features, such as the distance-independent conductance and its\nquadratic dependence on the carrier concentration, as opposed to the linear\ndependence in uniform graphene.",
        "positive": "Giant spin-polarized current in a Dirac fermion system at cyclotron\n  resonance: We report on the observation of the giant spin-polarized photocurrent in\nHgTe/HgCdTe quantum well (QW) of critical thickness at which a Dirac spectrum\nemerges. Exciting QW of 6.6 nm width by terahertz (THz) radiation and sweeping\nmagnetic field we detected a resonant photocurrent. Remarkably, the position of\nthe resonance can be tuned from negative (-0.4 T) to positive (up to 1.2 T)\nmagnetic fields by means of optical gating. The photocurent data, accompanied\nby measurements of radiation transmission as well as Shubnikov-de Haas and\nquantum Hall effects, give an evidence that the enhancement of the photocurrent\nis caused by cyclotron resonance in a Dirac fermion system. The developed\ntheory shows that the current is spin polarized and originates from the spin\ndependent scattering of charge carriers heated by the radiation."
    },
    {
        "anchor": "Role of acoustic phonons in exotic conductivity of two-dimensional Dirac\n  electrons: We examine the effect of acoustic phonon scattering on the conductivity of\ntwo-dimensional Dirac electrons. The temperature ($T$) dependence of the\nconductivity ($\\sigma$) is calculated using the electron Green's function with\ndamping by both the impurity ($\\Gamma_0$) and phonon ($\\Gamma_{\\rm ph}$).For\nzero or small doping, on which the present Rapid Communication focuses, $\\sigma\n(T)$ increases and becomes almost constant due to the competition between the\nDirac electrons and the phonon scattering. Such strange behavior of $\\sigma\n(T)$ is ascribed to an exotic mechanism of phonon scattering, whose momentum\nspace is strongly reduced in the presence of a Dirac cone. For large doping,\n$\\sigma$ decreases due to the interplay of the Fermi surface and the phonon.\nThe unconventional $T$ dependence of the resistivity $\\rho (=1/\\sigma)$ for\nsmall doping is compared with that of the experiment of Dirac electrons in an\norganic conductor.",
        "positive": "Temperature Dependence of Microwave Photoresistance in 2D Electron\n  Systems: We report on the temperature dependence of microwave-induced resistance\noscillations in high-mobility two-dimensional electron systems. We find that\nthe oscillation amplitude decays exponentially with increasing temperature, as\n$\\exp(-\\alpha T^2)$, where $\\alpha$ scales with the inverse magnetic field.\nThis observation indicates that the temperature dependence originates primarily\nfrom the modification of the single particle lifetime, which we attribute to\nelectron-electron interaction effects."
    },
    {
        "anchor": "Simulation of the Magnetization Dynamics of a Single Domain BiFeO$_3$\n  Thin Film: The switching dynamics of a single-domain BiFeO$_3$ thin films is\ninvestigated through combining the dynamics of polarization and Neel vector.\nThe evolution of the ferroelectric polarization is described by the\nLandau-Khalatnikov (LK) equation, and the Landau-Lifshitz-Gilbert (LLG)\nequations for spins in two sublattices to model the time evolution of the\nantiferromagnetic order (Neel vector) in a G-type antiferromagnet. This work\ntheoretically demonstrates that due to the rotation of the magnetic hard axis\nfollowing the polarization reversal, the Neel vector can be switched by 180\ndegrees, while the weak magnetization can remain unchanged. The simulation\nresults are consistent with the ab initio calculation, where the Neel vector\nrotates during polarization rotation, and also match our calculation of the\ndynamics of order parameter using Landau-Ginzburg theory. We also find that the\nswitching time of the Neel vector is determined by the speed polarization\nswitching and is predicted to be as short as 30 ps.",
        "positive": "Electron paramagnetic resonance detected via magnetization measurements: Presented are magnetization measurements on a crystal of Fe8 single-molecule\nmagnets using a Hall probe magnetometer. Irradiation with microwaves at\nfrequencies of 92 and 110-120 GHz leads to the observation of electron\nparamagnetic resonance (EPR) detected via magnetization measurements. A\nquantitative analysis of the results are introduced by means of the spin\ntemperature. It is shown that pulsed microwave experiments allow a better\ncontrol over the spin excitation."
    },
    {
        "anchor": "Electrical control of a solid-state flying qubit: Solid-state approaches to quantum information technology are attractive\nbecause they are scalable. The coherent transport of quantum information over\nlarge distances, as required for a practical quantum computer, has been\ndemonstrated by coupling solid-state qubits to photons1. As an alternative\napproach for a spin-based quantum computer, single electrons have also been\ntransferred between distant quantum dots in times faster than their coherence\ntime2, 3. However, there have been no demonstrations to date of techniques that\ncan coherently transfer scalable qubits and perform quantum operations on them\nat the same time. The resulting so-called flying qubits are attractive because\nthey allow for control over qubit separation and non-local entanglement with\nstatic gate voltages, which is a significant advantage over other solid-state\nqubits in confined systems for integration of quantum circuits. Here we report\nthe transport and manipulation of qubits over distances of 6 microns within 40\nps, in an Aharonov-Bohm ring connected to two-channel wires that have a tunable\ntunnel coupling between channels. The flying qubit state is defined by the\npresence of a travelling electron in either channel of the wire, and can be\ncontrolled without a magnetic field. Our device has shorter quantum gates,\nlonger coherence lengths (~86 {\\mu}m at 70 mK), and shorter operation times\n(~10 ps or 100 GHz) than other solid-state flying qubit implementations4, 5,\nwhich makes our solid-state flying qubit potentially scalable.",
        "positive": "Existence of zero-energy impurity states in different classes of\n  topological insulators and superconductors and their relation to topological\n  phase transitions: We consider the effects of impurities on topological insulators and\nsuperconductors. We start by identifying the general conditions under which the\neigenenergies of an arbitrary Hamiltonian H belonging to one of the\nAltland-Zirnbauer symmetry classes undergo a robust zero energy crossing as a\nfunction of an external parameter which can be, for example, the impurity\nstrength. We define a generalized root of \\det H, and use it to predict or rule\nout robust zero-energy crossings in all symmetry classes. We complement this\nresult with an analysis based on almost degenerate perturbation theory, which\nallows a derivation of the asymptotic low-energy behavior of the ensemble\naveraged density of states $\\rho \\sim E^\\alpha$ for all symmetry classes, and\nmakes it transparent that the exponent \\alpha\\ does not depend on the choice of\nthe random matrix ensemble. Finally, we show that a lattice of impurities can\ndrive a topologically trivial system into a nontrivial phase, and in particular\nwe demonstrate that impurity bands carrying extremely large Chern numbers can\nappear in different symmetry classes of two-dimensional topological insulators\nand superconductors. We use the generalized root of \\det H(k) to reveal a\nspiderweblike momentum space structure of the energy gap closings that separate\nthe topologically distinct phases in p_x + i p_y superconductors in the\npresence of an impurity lattice."
    },
    {
        "anchor": "Electronic Transport in Metal Nanocrystal Arrays: The Effect of\n  Structural Disorder on Scaling Behavior: We investigate the impact of structural disorder on electronic transport in\ngold nanocrystal monolayers. Arrays ranging from void-filled networks to\nwell-ordered superlattices show clear voltage thresholds V_T due to Coulomb\nblockade, and temperature-independent conduction indicative of quantum\ntunneling. Current-voltage characteristics of arrays with and without\nlong-range structural order were found to collapse onto distinct scaling\ncurves. The former follow a single power-law: I (V-V_T)^\\zeta, \\zeta =\n2.25+/-0.1. The latter show additional structure, reflecting the underlying\ndisordered topology.",
        "positive": "Magnon quantum anomalies in Weyl ferromagnets: When subjected to parallel electric field $\\mathbf E$ and magnetic field\n$\\mathbf B$, Weyl semimetals exhibit the exotic transport property known as the\nchiral anomaly due to the pumping of electrons between Weyl cones of opposite\nchiralities. When one or both electromagnetic (EM) fields are replaced by\nstrain-induced chiral pseudo-electromagnetic (pseudo-EM) fields, other types of\nquantum anomalies occur. In the present paper, we will show that such quantum\nanomalies can be reproduced in a completely different system -- a Weyl\nferromagnet whose magnonic structure remarkably encodes Weyl physics. By\nanalytical and numerical calculations, we will show that the magnon bands can\nbe Landau-quantized by either an inhomogeneous electric field $\\mathbf E$ or a\nchiral pseudo-electric field $\\mathbf e$ induced by a torsional strain, and\nmagnons can be pumped along bands by either an inhomogeneous magnetic field\n$\\mathbf B$ or a chiral pseudo-magnetic field $\\mathbf b$ due to a dynamic\nuniaxial strain. We list the magnon quantum anomalies and the associated\nanomalous spin and heat currents in the Weyl ferromagnet, and show they are\ndistinct from their Weyl semimetal counterparts."
    },
    {
        "anchor": "Taking advantage of light- and heavy-hole trions for optical spin\n  initialization, control and readout: Optical control strategies in semiconductor nanostructures have almost\nexclusively relied on heavy-hole exciton and trion states. In the first part of\nthis letter, we show that light-hole trions provide the missing ressource for\nconsolidating all single qubit operations in a mutually compatible magnetic\nfield configuration: electron spin initialization and control can be achieved\nthrough light-hole trion states and cycling transition is provided by\nheavy-hole trion states. In the second part, we experimentally demonstrate that\npairs of nitrogen atoms in GaAs exhibiting a Cs symmetry bind both light- and\nheavy-hole excitons and negative trions. A detailed analysis of the fine\nstructure reveals that that trion states provide the lambda level structure\nnecessary for fast initialization and control along with\nenergetically-protected cycling transition compatible with single-shot readout.",
        "positive": "Multiple quantum wells for PT-symmetric phononic crystals: We demonstrate that the parity-time symmetry for sound is realized in the\nlaser-pumped multiple-quantum-well structure. Breaking of the parity-time\nsymmetry for the phonons with wave vectors corresponding to the Bragg condition\nmakes the structure a highly-selective acoustic wave amplifier. Single-mode\ndistributed feedback phonon lasing is predicted for structures with realistic\nparameters."
    },
    {
        "anchor": "Charge Transport through Conjugated Azomethine-based Single Molecules\n  for Optoelectronic Applications: The single-molecule conductance of a 3-ring, conjugated azomethine was\nstudied using the mechanically controlled breakjunction technique. Charge\ntransport properties are found to be comparable to vinyl-based analogues;\nfindings are supported with density functional calculations. The simple\npreparation and good transport properties make azomethine-based molecules an\nattractive class for use in polymer and single-molecule organic electronics.",
        "positive": "Signature of the Overhauser field on the coherent spin dynamics of\n  donor-bound electron in a single CdTe quantum well: We have studied the coherent spin dynamics in an oblique magnetic field of\nelectrons localized on donors and placed in the middle of a single CdTe quantum\nwell, by using a time-resolved optical technique: the photo-induced Faraday\nrotation. We showed that this dynamics is affected by a weak Overhauser field\ncreated via the hyperfine interaction of optically spin-polarized donor-bound\nelectrons with the surrounding nuclear isotopes carrying non-zero spins. We\nhave measured this nuclear field, which is on the order of a few mT and can\nreach a maximum experimental value of 9.4 mT. This value represents 13 % of the\nmaximal nuclear polarization, and corresponds also to 13 % of maximal\nelectronic polarization."
    },
    {
        "anchor": "Theory of Unconventional Spin States in Surfaces with Non-Rashba\n  Spin-Orbit Interaction: Surface states in Tl/Si(111) and Bi/Si(111) show non-Rashba-type spin\nsplitting. We study spin-transport properties in these surface states. First we\nconstruct tight-binding Hamiltonians for Tl/Si and Bi/Si surfaces, which\nrespect crystallographic symmetries. As a result, we find specific terms in the\nTl/Si surface Hamiltonian responsible for non-Rashba spin splitting. Using this\nmodel we calculate current-induced spin polarization in the Tl/Si Hamiltonian\nin order to see the effect of non-Rashba spin-orbit interaction. We found that\nthe induced spin polarization is in-plane and perpendicular to the current,\nwhich is consequently the same with Rashba systems. We find that it follows\nfrom crystallographic symmetries. Furthermore, we numerically find bound states\nat the junction between two surface regions which have different signs of the\nspin-orbit interaction parameters in the Bi/Si system and in the Tl/Si system.\nWe explain these numerical results with the results of our analytical\ncalculations.",
        "positive": "The impacts of the quantum-dot confining potential on the spin-orbit\n  effect: For a nanowire quantum dot with the confining potential modeled by both the\ninfinite and the finite square wells, we obtain exactly the energy spectrum and\nthe wave functions in the strong spin-orbit coupling regime. We find that\nregardless of how small the well height is, there are at least two bound states\nin the finite square well: one has the $\\sigma^{x}\\mathcal{P}=-1$ symmetry and\nthe other has the $\\sigma^{x}\\mathcal{P}=1$ symmetry. When the well height is\nslowly tuned from large to small, the position of the maximal probability\ndensity of the first excited state moves from the center to $x\\ne0$, while the\nposition of the maximal probability density of the ground state is always at\nthe center. A strong enhancement of the spin-orbit effect is demonstrated by\ntuning the well height. In particular, there exists a critical height\n$V^{c}_{0}$, at which the spin-orbit effect is enhanced to maximal."
    },
    {
        "anchor": "Size scaling of the addition spectra in silicon quantum dots: We investigate small artificial quantum dots obtained by geometrically\ncontrolled resistive confinement in low mobility silicon-on-insulator\nnanowires. Addition spectra were recorded at low temperature for various dot\nareas fixed by lithography. We compare the standard deviation of the addition\nspectra with theory in the high electron concentration regime. We find that the\nstandard deviation scales as the inverse area of the dot and its absolute value\nis comparable to the energy spacing of the one particle spectrum.",
        "positive": "Edge magnetism of Heisenberg model on honeycomb lattice: In our previous study, a single-branch of ferromagnetic magnon with linear\ndispersion is shown to exist near the (uncompensated) zigzag edge for\nHeisenberg model on honeycomb lattice. Here we develop a field-theory\ndescription for the edge magnon and find its dynamics is captured by the\none-dimensional relativistic Klein-Gordon equation. It is intriguing that the\nboundary field theory for the edge magnon is tied up with its bulk counterpart,\ndescribed by the two-dimensional Klein-Gordon equation. Furthermore, we also\nreveal how the parity symmetry relates evanescent modes on opposite edges in a\nhoneycomb nanoribbon. By employing alternative methods, including Schwinger\nbosons and density-matrix renormalization group, we also demonstrate that the\nrelativistic edge magnon is robust even when the Neel order in the bulk is\ndestroyed by quantum fluctuations. The edge magnon is a direct consequence of\nuncompensated edge and may be verified in realistic materials by experimental\nprobes."
    },
    {
        "anchor": "Electrically tunable Kondo effect as a direct measurement of the chiral\n  anomaly in disorder Weyl semimetals: We propose a mechanism to directly measure the chiral anomaly in disorder\nWeyl semimetals (WSMs) by the Kondo effect. We find that in a magnetic and\nelectric field driven WSM, the locations of the Kondo peaks can be modulated by\nthe chiral chemical potential, which is proportional to $\\mathbf{E}\\cdot\n\\mathbf{B}$. The Kondo peaks come from spin fluctuations within the impurities,\nwhich apart from the temperature, relate closely to the host's Fermi level. In\nWSMs, the chiral-anomaly-induced chirality population imbalance will shift the\nlocal Fermi levels of the paired Weyl valleys toward opposite directions in\nenergy, and then affects the Kondo effect. Consequently, the Kondo effect can\nbe tunable by an external electric field via the chiral chemical potential.\nThis is unique to the chiral anomaly. Base on this, we argue that the\nelectrically tunable Kondo effect can serve as a direct measurement of the\nchiral anomaly in WSMs. The Kondo peaks are robust against the disorder effect\nand therefore, the signal of the chiral anomaly survives for a relatively weak\nmagnetic field.",
        "positive": "Scaleability of dielectric susceptibility $\u03b5_{zz}$ with the\n  number of layers and additivity of ferroelectric polarization in van der\n  Waals semiconductors: We study the dielectric response of few layered crystals of various\ntransition metal dichalcogenides (TMDs) and hexagonal Boron Nitride (hBN). We\nshowed that the out-of-plane polarizability of a multilayer crystal (which\ncharacterizes response to the external displacement field) scales linearly with\nthe number of layers, $\\alpha_{zz}^{NL} =N \\alpha_{zz}^{1L}$, independently of\nthe stacking configuration in the film. We also established additivity of\nferroelectric polarizations of consecutive interfaces in case when such\ninterfaces have broken inversion symmetry. Then we used the obtained data of\nmonolayer $\\alpha_{zz}^{1L}$ to calculate the values of the dielectric\nsusceptibilities for semiconductor TMDs and hBN bulk crystals."
    },
    {
        "anchor": "Calculation of energy-barrier lowering by incoherent switching in\n  STT-MRAM: To make a useful STT-MRAM (spin-transfer torque magnetoresistive\nrandom-access memory) device, it is necessary to be able to calculate switching\nrates, which determine the error rates of the device. In a single-macrospin\nmodel, one can use a Fokker-Planck equation to obtain a low-current thermally\nactivated rate $\\propto \\exp(-E_{eff}/k_B T)$. Here the effective energy\nbarrier $E_{eff}$ scales with the single-macrospin energy barrier $KV$, where\n$K$ is the effective anisotropy energy density and $V$ the volume. A\nlong-standing paradox in this field is that the actual energy barrier appears\nto be much smaller than this. It has been suggested that incoherent motions may\nlower the barrier, but this has proved difficult to quantify. In the present\npaper, we show that the coherent precession has a magnetostatic instability,\nwhich allows quantitative estimation of the energy barrier and may resolve the\nparadox.",
        "positive": "The chiral Hall effect of magnetic skyrmions from a cyclic cohomology\n  approach: We demonstrate the emergence of an anomalous Hall effect in chiral magnetic\ntextures which is neither proportional to the net magnetization nor to the\nwell-known emergent magnetic field that is responsible for the topological Hall\neffect. Instead, it appears already at linear order in the gradients of the\nmagnetization texture and exists for one-dimensional magnetic textures such as\ndomain walls and spin spirals. It receives a natural interpretation in the\nlanguage of Alain Connes' noncommutative geometry. We show that this chiral\nHall effect resembles the familiar topological Hall effect in essential\nproperties while its phenomenology is distinctly different. Our findings make\nthe re-interpretation of experimental data necessary, and offer an exciting\ntwist in engineering the electrical transport through magnetic skyrmions."
    },
    {
        "anchor": "MEMS-EYE: A M/NEMS platform for the investigation of multi-physical and\n  complex nonlinear systems: The ultimate goal of this research proposal is the creation of a\nmicro-optomechanical intelligence. The proposal centers on the development and\ninvestigation of very large-scale integrated (VLSI) arrays of coupled M/NEMS\ndevices as platforms for the experimental study of nonlinear dynamics of\nhigh-dimensional systems. The potential of VLSI M/NEMS arrays to function as\nadvanced sensors will be demonstrated through the novel idea of a MEMS EYE, an\nelectronics-free platform that combines imaging and pattern recognition\nfunctionality.",
        "positive": "Orbits in Large Aluminum Clusters: Five-Pointed Stars: The distinctions in the mass spectra of large sodium (Na_N) and aluminum\n(Al_N) clusters are discussed. A semiclassical method is used to describe the\nshell effects within a spherical jellium model. It allows one to analyze the\nrelative role of different classical trajectories in the formation of\nelectronic supershells in clusters of various sizes at zero and finite\ntemperatures. A criterion for the hardness of the self-consistent potential is\nformulated. The conjecture that the five-point-star trajectories make the main\ncontribution to the spectral oscillations for large soft-potential Al_N\n(250<N<900) clusters is substantiated. The computational results are in\nagreement with the mass spectra of the Al_N clusters at T ~ 300 K."
    },
    {
        "anchor": "Nonlocal hydrodynamic phonon transport in two-dimensional materials: We study hydrodynamic phonon heat transport in two-dimensional (2D)\nmaterials. Starting from the Peierls-Boltzmann equation within the Callaway\nmodel, we derive a 2D Guyer-Krumhansl-like equation describing non-local\nhydrodynamic phonon transport, taking into account the quadratic dispersion of\nflexural phonons. In additional to Poiseuille flow, second sound propagation,\nthe equation predicts heat current vortices and negative nonlocal thermal\nconductance in 2D materials, common in classical fluid but scarcely considered\nin phonon transport. Our results also illustrate the universal transport\nbehavior of hydrodynamics, independent on the type of quasi-particles and their\nmicroscopic interactions.",
        "positive": "Decoherence of fermions subject to a quantum bath: The destruction of quantum-mechanical phase coherence by a fluctuating\nquantum bath has been investigated mostly for a single particle. However, for\nelectronic transport through disordered samples and mesoscopic interference\nsetups, we have to treat a many-fermion system subject to a quantum bath. Here,\nwe review a novel technique for treating this situation in the case of\nballistic interferometers, and discuss its application to the electronic\nMach-Zehnder setup. We use the results to bring out the main features of\ndecoherence in a many-fermion system, and briefly discuss the same ideas in the\ncontext of weak localization."
    },
    {
        "anchor": "Interlayer coupling in ferromagnetic semiconductor superlattices: We develop a mean-field theory of carrier-induced ferromagnetism in diluted\nmagnetic semiconductors. Our approach represents an improvement over standard\nRKKY model allowing spatial inhomogeneity of the system, free-carrier spin\npolarization, finite temperature, and free-carrier exchange and correlation to\nbe accounted for self-consistently. As an example, we calculate the electronic\nstructure of a Mn$_x$Ga$_{1-x}$As/GaAs superlattice with alternating\nferromagnetic and paramagnetic layers and demonstrate the possibility of\nsemiconductor magnetoresistance systems with designed properties.",
        "positive": "Suppression of the Persistent Spin Hall Current by Defect Scattering: We study the linear response spin Hall conductivity of a two-dimensional\nelectron gas (2DEG) in the presence of the Rashba spin orbit interaction in the\ndiffusive transport regime. When defect scattering is modeled by isotropic\nshort-range potential scatterers the spin Hall conductivity vanishes due to the\nvertex correction. A non-vanishing spin Hall effect may be recovered for\ndominantly forward defect scattering."
    },
    {
        "anchor": "Dresselhaus spin-orbit coupling in [111]-oriented semiconductor\n  nanowires: The contribution of bulk inversion asymmetry to the total spin-orbit coupling\nis commonly neglected for group III-V nanowires grown in the generic [111]\ndirection. We have solved the complete Hamiltonian of the circular nanowire\naccounting for bulk inversion asymmetry via exact numerical diagonalization.\nThree different symmetry classes of angular momentum states exist, which\nreflects the threefold rotation symmetry of the crystal lattice about the [111]\naxis. A particular group of angular momentum states contains degenerate modes\nwhich are strongly coupled via the Dresselhaus Hamiltonian, which results in a\nsignificant energy splitting with increasing momentum. Hence, under certain\nconditions Dresselhaus spin-orbit coupling is relevant for [111] InAs and [111]\nInSb nanowires. We demonstrate momentum-dependent energy splittings and the\nimpact of Dresselhaus spin-orbit coupling on the dispersion relation. In view\nof possible spintronics applications relying on bulk inversion asymmetry we\ncalculate the spin expectation values and the spin texture as a function of the\nFermi energy. Finally, we investigate the effect of an axial magnetic field on\nthe energy spectrum and on the corresponding spin polarization.",
        "positive": "Charge transfer of edge states in zigzag silicene nanoribbons with\n  Stone-Wales defects: Stone-Wales (SW) defects are favorably existed in graphenelike materials with\nhoneycomb lattice structure and potentially employed to change the electronic\nproperties in band engineering. In this paper, we investigate structural and\nelectronic properties of SW defects in bulk silicene and its nanoribbons as a\nfunction of their concentration using the methods of periodic boundary\nconditions with first-principles calculations. We first calculate the formation\nenergy, structural properties, and electronic band structures of SW defects in\nbulk silicene, with dependence on the concentration of SW defects. Our results\nshow a good agreement with available values from the previous first-principles\ncalculations. The energetics, structural aspects, and electronic properties of\nSW defects with dependence on defect concentration and location in\nedge-hydrogenated zigzag silicene nanoribbons are obtained. For all calculated\nconcentrations, the SW defects prefer to locate at the edge due to the lower\nformation energy. The SW defects at the center of silicene nanoribbons slightly\ninfluence on the electronic properties, whereas the SW defects at the edge of\nsilicene nanoribbons split the degenerate edge states and induce a sizable gap,\nwhich depends on the concentration of defects. It is worth to find that the SW\ndefects produce a perturbation repulsive potential, which leads the decomposed\ncharge of edge states at the side with defect to transfer to the other side\nwithout defect."
    },
    {
        "anchor": "Interband transitions in narrow-gap carbon nanotubes and graphene\n  nanoribbons: We use the robust nearest-neighbour tight-binding approximation to study on\nthe same footing interband dipole transitions in narrow-bandgap carbon\nnanotubes and graphene nanoribbons. It is demonstrated that curvature effects\nin metallic single-walled carbon nanotubes and edge effects in gapless graphene\nnanoribbons not only open up bang gaps, which typically correspond to THz\nfrequencies, but also result in a giant enhancement of the probability of\noptical transitions across these gaps. Moreover, the matrix element of the\nvelocity operator for these transitions has a universal value (equal to the\nFermi velocity in graphene) when the photon energy coincides with the band-gap\nenergy. Upon increasing the excitation energy, the transition matrix element\nfirst rapidly decreases (for photon energies remaining in the THz range but\nexceeding two band gap energies it is reduced by three orders of magnitude),\nand thereafter it starts to increase proportionally to the photon frequency. A\nsimilar effect occurs in an armchair carbon nanotube with a band gap opened and\ncontrolled by a magnetic field applied along the nanotube axis. There is a\ndirect correspondence between armchair graphene nanoribbons and single-walled\nzigzag carbon nanotubes. The described sharp photon-energy dependence of the\ntransition matrix element together with the van Hove singularity at the band\ngap edge of the considered quasi-one-dimensional systems make them promising\ncandidates for active elements of coherent THz radiation emitters. The effect\nof Pauli blocking of low-energy interband transitions caused by residual doping\ncan be suppressed by creating a population inversion using high-frequency\n(optical) excitation.",
        "positive": "Investigation of Surface State of Topological Kondo Insulator with\n  Rashba Impurities: We study a generic topological Kondo insulator system by performing a\nmean-field theoretic calculation within the frame-work of slave-boson protocol.\nWe assume infinite Hubbard-type interaction among the localized electrons. The\ndifference between the bulk metallic and insulating phases of the insulator is\nin the sign of nearest neighbor hopping of localized electrons. The hopping\namplitude is positive for the metallic and negative for the insulating phase.\nThe surface metallicity together with bulk insulation, however, requires very\nstrong f electron localization. Furthermore, we find that the exchange field,\narising due to the presence of the magnetic impurities on the surface of the\nsystem, opens a gap at the gapless Dirac dispersion of the surface states. For\nthe gapped surface state spectrum, we find the possibility of intra-band as\nwell as inter-band unconventional plasmons. The paramountcy of the bulk\nmetallicity, and, in the presence of the Rashba impurities, the insulator\nsurface comprising of helical liquids are the important outcomes of the present\ncommunication. The access to the gapless Dirac spectrum leads to spin plasmons\nwith the usual wave vector dependence q^1/2. The Rashba coupling does not\nimpair the Kondo screening and does not affect the quantum critical point for\nthe bulk."
    },
    {
        "anchor": "Spin-texture and magnetic anisotropy of Co adsorbed Bi$_2$Se$_3$\n  topological insulator surfaces: Based upon first-principles methods, we investigate the magnetic anisotropy\nand the spin-texture of Co adatoms embedded in the topmost Se network of the\ntopological insulator Bi$_2$Se$_3$ surface. We find the formation of\nenergetically stable magnetic moment perpendicular to the surface plane, S$_z$.\nOur results for the pristine Bi$_2$Se$_3$ surface indicate the presence of\nhelical spin-texture not only in the massless surface Dirac states, but also\nsurface states resonant within the valence band present spin-texture. On the\nother hand, upon the presence of Co adatoms we find that the out-of-plane\nsurface magnetism represents the dominant spin state (S$_z$), while the planar\nspin components, S$_x$ and S$_y$, are almost suppressed.",
        "positive": "Graphene-based three-body amplification of photon heat tunneling: We consider a three slabs configuration including two non-doped single layer\ngraphene on insulating silicon dioxide (G/SiO2) substrates and one non-doped\nsuspended single layer graphene (SG). The suspended layer is placed between two\nG/SiO2 layers. Without SG layer, the heat flux has maximum at Plasmon frequency\nsupported by the G/SiO2 slabs. In three slabs configuration, the photon heat\ntunneling is amplified between two G/SiO2 layers significantly, only for\nspecific range of vacuum gap between SG layer and G/SiO2 layers and Plasmon\nfrequency, due to the coupling of modes between each G/SiO2 layer and SG layer.\nSince, the SG layer is a single atomic layer, the photon heat tunneling\nassisted by this configuration does not depend on the thickness of middle layer\nand in consequence, it can enable novel applications for nanoscale thermal\nmanagement."
    },
    {
        "anchor": "Charge dynamics in near-surface, variable-density ensembles of\n  nitrogen-vacancy centers in diamond: Although the spin properties of superficial shallow nitrogen-vacancy (NV)\ncenters have been the subject of extensive scrutiny, considerably less\nattention has been devoted to studying the dynamics of NV charge conversion\nnear the diamond surface. Using multi-color confocal microscopy, here we show\nthat near-surface point defects arising from high-density ion implantation\ndramatically increase the ionization and recombination rates of shallow NVs\ncompared to those in bulk diamond. Further, we find that these rates grow\nlinearly not quadratically with laser intensity, indicative of single-photon\nprocesses enabled by NV state mixing with other defect states. Accompanying\nthese findings we observe NV ionization and recombination in the dark, likely\nthe result of charge transfer to neighboring traps. In spite of the altered\ncharge dynamics, we show one can imprint rewritable, long-lasting patterns of\ncharged-initialized, near-surface NVs over large areas, an ability that could\nbe exploited for electrochemical biosensing or to optically store digital data\nsets with sub-diffraction resolution.",
        "positive": "Universality of the Kondo Effect in a Quantum Dot out of Equilibrium: We study the Kondo effect in a quantum dot driven out of equilibrium by an\nexternal ac field. The Kondo effect can be probed by measuring the dc current\ninduced by an auxiliary dc bias $V_{dc}$ applied across the dot. In the absence\nof ac perturbation, the corresponding differential conductance $G(V_{dc})$ is\nknown to exhibit a sharp peak at $V_{dc}=0$, which is the manifestation of the\nKondo effect. In the equilibrium, there exists only one energy scale, the Kondo\ntemperature $T_K$, which controls all the low-energy physics of the system; $G$\nis some universal function of $eV_{dc}/T_K$. We demonstrate that the dot out of\nequilibrium is also characterized by a universal behavior: conductance $G$\ndepends on the ac field only through two dimensionless parameters, which are\nthe frequency $\\omega$ and the amplitude of the ac perturbation, both divided\nby $T_K$. We find analytically the large- and small-frequency asymptotes of the\nuniversal dependence of $G$ on these parameters. The obtained results allow us\nto predict the behavior of the conductance in the crossover regime\n$\\hbar\\omega\\sim T_K$."
    },
    {
        "anchor": "Tomography of zero-energy end modes in topological superconducting wires: We characterize the Majorana zero modes in topological hybrid\nsuperconductor-semiconductor wires with spin-orbit coupling and magnetic field,\nin terms of generalized Bloch coordinates $\\varphi, \\theta, \\delta$, and\nanalyze their transformation under SU(2) rotations. We show that, when the\nspin-orbit coupling and the magnetic field are perpendicular, $\\varphi$ and\n$\\delta$ are universal in an appropriate coordinate system. We use these\ngeometric properties to explain the behavior of the Josephson current in\njunctions of two wires with different orientations of the magnetic field and/or\nthe spin-orbit coupling. We show how to extract from there, the angle $\\theta$,\nhence providing a full description of the Majorana modes.",
        "positive": "Modification of the Lifshitz-Kosevich formula for anomalous quantum\n  oscillations in inverted insulators: It is generally believed that quantum oscillations are a hallmark of a Fermi\nsurface and the oscillations constitute the ringing of it. Recently, it was\nunderstood that in order to have well defined quantum oscillations you do not\nonly not need well defined quasiparticles, but also the presence of a Fermi\nsurface is unnecessary. In this paper we investigate such a situation for an\ninverted insulator from a analytical point of view. Even in the insulating\nphase clear signatures of quantum oscillations are observable and we give a\nfully analytical formula for the strongly modified Lifshitz-Kosevich amplitude\nwhich applies in the clean as well as the disordered case at finite\ntemperatures."
    },
    {
        "anchor": "Interacting electrodynamics of short coherent conductors in quantum\n  circuits: When combining lumped mesoscopic electronic components to form a circuit,\nquantum fluctuations of electrical quantities lead to a non-linear\nelectromagnetic interaction between the components that is not generally\nunderstood. The Landauer-B\\\"uttiker formalism that is frequently used to\ndescribe non-interacting coherent mesoscopic components is not directly suited\nto describe such circuits since it assumes perfect voltage bias, i.e. the\nabsence of fluctuations. Here, we show that for short coherent conductors of\narbitrary transmission, the Landauer-B\\\"uttiker formalism can be extended to\ntake into account quantum voltage fluctuations similarly to what is done for\ntunnel junctions. The electrodynamics of the whole circuit is then formally\nworked out disregarding the non-Gaussianity of fluctuations. This reveals how\nthe aforementioned non-linear interaction operates in short coherent\nconductors: voltage fluctuations induce a reduction of conductance through the\nphenomenon of dynamical Coulomb blockade but they also modify their internal\ndensity of states leading to an additional electrostatic modification of the\ntransmission. Using this approach we can account quantitatively for conductance\nmeasurements performed on Quantum Point Contacts in series with impedances of\nthe order of $R_K = h / e^2$. Our work should enable a better engineering of\nquantum circuits with targeted properties.",
        "positive": "Electronic triple-dot transport through a bilayer graphene island with\n  ultrasmall constrictions: A quantum dot has been etched in bilayer graphene connected by two small\nconstrictions to the leads. We show that this structure does not behave like a\nsingle quantum dot but consists of at least three sites of localized charge in\nseries. The high symmetry and electrical stability of the device allowed us to\ntriangulate the positions of the different sites of localized charge and find\nthat one site is located in the island and one in each of the constrictions.\nNevertheless we measure many consecutive single non-overlapping\nCoulomb-diamonds in series. In order to describe these findings, we treat the\nsystem as a strongly coupled serial triple quantum dot. We find that the\nnon-overlapping Coulomb diamonds arise due to higher order cotunneling through\nthe outer dots located in the constrictions. We extract all relevant\ncapacitances, simulate the measured data with a capacitance model and discuss\nits implications on electrical transport."
    },
    {
        "anchor": "Terahertz bolometric detectors based on graphene field-effect\n  transistors with the composite h-BN/black-P/h-BN gate layers using plasmonic\n  resonances: We propose and analyze the performance of terahertz (THz) room-temperature\nbolometric detectors based on the graphene channel field-effect transistors\n(GC-FET). These detectors comprise the gate barrier layer (BL) composed of the\nlateral hexagonal-Boron Nitride black-Phosphorus/ hexagonal-Boron Nitride\n(h-BN/b-P/h-BN) structure. The main part of the GC is encapsulated in h-BN,\nwhereas a short section of the GC is sandwiched between the b-P gate BL and the\nh-BN bottom layer. The b-P gate BL serves as the window for the electron\nthermionic current from the GC. The electron mobility in the GC section\nencapsulated in h-BN can be fairly large. This might enable a strong resonant\nplasmonic response of the GC-FET detectors despite relatively lower electron\nmobility in the GC section covered by the b-P window BL. The narrow b-P window\ndiminishes the Peltier cooling and enhances the detector performance. The\nproposed device structure and its operation principle promote elevated values\nof the room-temperature GC-FET THz detector responsivity and other\ncharacteristics, especially at the plasmonic resonances.",
        "positive": "Floquet Valley-Polarized Quantum Anomalous Hall State in Nonmagnetic\n  Heterobilayers: The valley-polarized quantum anomalous Hall (VQAH) state, which forwards a\nstrategy for combining valleytronics and spintronics with nontrivial topology,\nattracts intensive interest in condensed-matter physics. So far, the explored\nVQAH states have still been limited to magnetic systems. Here, using the\nlow-energy effective model and Floquet theorem, we propose a different\nmechanism to realize the Floquet VQAH state in nonmagnetic heterobilayers under\nlight irradiation. We then realize this proposal via first-principles\ncalculations in transition metal dichalcogenide heterobilayers, which initially\npossess the time-reversal invariant valley quantum spin Hall (VQSH) state. By\nirradiating circularly polarized light, the time-reversal invariant VQSH state\ncan evolve into the VQAH state, behaving as an optically switchable topological\nspin-valley filter. These findings not only offer a rational scheme to realize\nthe VQAH state without magnetic orders, but also pave a fascinating path for\ndesigning topological spintronic and valleytronic devices."
    },
    {
        "anchor": "Manipulating the Quantum State of an Electrical Circuit: We have designed and operated a superconducting tunnel junction circuit that\nbehaves as a two-level atom: the ``quantronium''. An arbitrary evolution of its\nquantum state can be programmed with a series of microwave pulses, and a\nprojective measurement of the state can be performed by a pulsed readout\nsub-circuit. The measured quality factor of quantum coherence Qphi=25000 is\nsufficiently high that a solid-state quantum processor based on this type of\ncircuit can be envisioned.",
        "positive": "Size-reduction of nanodiamonds via air oxidation: Here we report the size reduction and effects on nitrogen-vacancy centres in\nnanodiamonds by air oxidation using a combined atomic force and confocal\nmicroscope. The average height reduction of individual crystals as measured by\natomic force microscopy was 10.6 nm/h at 600 {\\deg}C air oxidation at\natmospheric pressure. The oxidation process modified the surface including\nremoval of non-diamond carbon and organic material which also led to a decrease\nin background fluorescence. During the course of the nanodiamond size\nreduction, we observed the annihilation of nitrogen-vacancy centres which\nprovided important insight into the formation of colour centres in small\ncrystals. In these unirradiated samples, the smallest nanodiamond still hosting\na stable nitrogen-vacancy centre observed was 8 nm."
    },
    {
        "anchor": "Silicon charge pump operation limit above and below liquid helium\n  temperature: Semiconductor tunable barrier single-electron pumps can produce output\ncurrent of hundreds of picoamperes at sub ppm precision, approaching the\nmetrological requirement for the direct implementation of the current standard.\nHere, we operate a silicon metal-oxide-semiconductor electron pump up to a\ntemperature of 14 K to understand the temperature effect on charge pumping\naccuracy. The uncertainty of the charge pump is tunnel limited below liquid\nhelium temperature, implying lowering the temperature further does not greatly\nsuppress errors. Hence, highly accurate charge pumps could be confidently\nachieved in a $^4$He cryogenic system, further promoting utilization of the\nrevised quantum current standard across the national measurement institutes and\nindustries worldwide.",
        "positive": "Quantum breathers in capacitively coupled Josephson junctions:\n  Correlations, number conservation, and entanglement: We consider the classical and quantum dynamics of excitations in a system of\ntwo capacitively coupled Josephson junctions. In the classical case the\nequations of motion admit discrete breather solutions, which are time periodic\nand localized predominantly on one of the junctions. In the quantum case\nbreather states are found in the central part of the energy spectrum of the\nconfined nonescaping states of the system. We perform a systematic analysis of\ntheir tunneling frequency, site correlations, fluctuations of the number of\nquanta, and entanglement. Quantum breather states show strong site correlation\nof quanta and are characterized by a strong excitation of quanta on one\njunction which perform slow coherent tunneling motion from one junction to the\nother. They suppress fluctuations of the total number of excited quanta.\nQuantum breather states are the least entangled states among the group of\neigenstates in the same range of the energy spectrum. We describe how quantum\nbreather excitations could be experimentally observed by employing the already\ndeveloped techniques for quantum information processing using Josephson\njunctions."
    },
    {
        "anchor": "Ultraclean two-dimensional hole systems with mobilities exceeding 10$^7$\n  cm$^2$/Vs: Owing to their large effective mass, strong and tunable spin-orbit coupling,\nand complex band-structure, two-dimensional hole systems (2DHSs) in GaAs\nquantum wells provide rich platforms to probe exotic many-body physics, while\nalso offering potential applications in ballistic and spintronics devices, and\nfault-tolerant topological quantum computing. We present here a systematic\nstudy of molecular-beam-epitaxy grown, modulation-doped, GaAs (001) 2DHSs where\nwe explore the limits of low-temperature 2DHS mobility by optimizing two\nparameters, the GaAs quantum well width and the alloy fraction ($x$) of the\nflanking Al$_x$Ga$_{1-x}$As barriers. We obtain a breakthrough in 2DHS\nmobility, with a peak value $\\simeq 18 \\times 10^6$ cm$^2$/Vs at a density of\n3.8 $\\times$ 10$^{10}$ /cm$^{2}$, implying a mean-free-path of $\\simeq 57\n\\mu$m. Using transport calculations tailored to our structures, we analyze the\noperating scattering mechanisms to explain the non-monotonic evolution of\nmobility with density. We find it imperative to include the dependence of\neffective mass on 2DHS density, well width, and $x$. We observe concomitant\nimprovement in quality as evinced by the appearance of delicate fractional\nquantum Hall states at very low density.",
        "positive": "Shuttle Instability in Self-Assembled Coulomb Blockade Nanostructures: We study a simple model of a self-assembled, room temperature\nCoulomb-blockade nanostructure containing a metallic nanocrystal or grain\nconnected by soft molecular links to two metallic electrodes. Self-excitation\nof periodic grain vibrations at 10 - 100 GHz is shown to be possible for a\nsufficiently large bias voltage leading to a novel `shuttle mechanism' of\ndiscrete charge transfer and a current through the nanostructure proportional\nto the vibration frequency. For the case of weak electromechanical coupling an\nanalytical approach is developed which together with Monte Carlo simulations\nshows that the shuttle instability for structures with high junction\nresistances leads to hysteresis in the current - voltage characteristics."
    },
    {
        "anchor": "Derivation of nonlinear single-particle equations via many-body Lindblad\n  superoperators: A density-matrix approach: A recently proposed Markov approach provides Lindblad-type scattering\nsuperoperators, which ensure the physical (positive-definite) character of the\nmany-body density matrix. We apply the mean-field approximation to such\nmany-body equation, in the presence of one- and two-body scattering mechanisms,\nand we derive a closed equation of motion for the electronic single-particle\ndensity matrix, which turns out to be non-linear as well as non-Lindblad. We\nprove that, in spite of its nonlinear and non-Lindblad structure, the\nmean-field approximation does preserve the positive-definite character of the\nsingle-particle density matrix, an essential prerequisite of any reliable\nkinetic treatment of semiconductor quantum devices. This result is in striking\ncontrast with conventional (non-Lindblad) Markov approaches, where the\nsingle-particle mean-field equations can lead to positivity violations and to\nunphysical results. Furthermore, the proposed single-particle formulation is\nextended to the case of quantum systems with spatial open boundaries, providing\na formal derivation of a recently proposed density-matrix treatment based on a\nLindblad-like system-reservoir scattering superoperator.",
        "positive": "Hybridisation at the organic-metal interface: a surface-scientific\n  analogue of H\u00fcckel's rule?: We demonstrate that cyclooctatetraene (COT) can be stabilised in different\nconformations when adsorbed on different noble-metal surfaces due to varying\nmolecule-substrate interaction. While at first glance the behaviour seems to be\nin accordance with H\\\"uckel's rule, a theoretical analysis reveals no\nsignificant charge transfer. The driving mechanism for the conformational\nchange is hybridisation at the organic-metal interface and does not necessitate\nany charge transfer."
    },
    {
        "anchor": "Gate-induced decoupling of surface and bulk state properties in\n  selectively-deposited Bi$_2$Te$_3$ nanoribbons: Three-dimensional topological insulators (TIs) host helical Dirac surface\nstates at the interface with a trivial insulator. In quasi-one-dimensional TI\nnanoribbon structures the wave function of surface charges extends\nphase-coherently along the perimeter of the nanoribbon, resulting in a\nquantization of transverse surface modes. Furthermore, as the inherent\nspin-momentum locking results in a Berry phase offset of $\\pi$ of\nself-interfering charge carriers an energy gap within the surface state\ndispersion appears and all states become spin-degenerate. We investigate and\ncompare the magnetic field dependent surface state dispersion in selectively\ndeposited Bi$_2$Te$_3$ TI micro- and nanoribbon structures by analysing the\ngate voltage dependent magnetoconductance at cryogenic temperatures. While in\nwide microribbon devices the field effect mainly changes the amount of bulk\ncharges close to the top surface we identify coherent transverse surface states\nalong the perimeter of the nanoribbon devices responding to a change in top\ngate potential. We quantify the energetic spacing in between these quantized\ntransverse subbands by using an electrostatic model that treats an initial\ndifference in charge carrier densities on the top and bottom surface as well as\nremaining bulk charges. In the gate voltage dependent transconductance we find\noscillations that change their relative phase by $\\pi$ at half-integer values\nof the magnetic flux quantum applied coaxial to the nanoribbon, which is a\nsignature for a magnetic flux dependent topological phase transition in narrow,\nselectively deposited TI nanoribbon devices.",
        "positive": "Magneto-optical Kerr effect and signature of the chiral anomaly in a\n  Weyl semimetal in a magnetic field: One striking property of the Landau level spectrum of a Weyl semimetal (WSM)\nis the existence of a chiral Landau level, in which the electrons propagate\nunidirectionally along the magnetic field. This linearly dispersive level\ninfluences the optical properties of WSMs. For example, it was recently shown\nthat a complete optical valley polarization is achievable in a time-reversal\nsymmetric Weyl semimetal placed in a magnetic field\\cite% {Bertrand2019}. This\neffect originates from inter-Landau level transitions involving the chiral\nLandau level and requires a tilt of the Weyl cones. In this paper, we show how\nthe magneto-optical Kerr effect (MOKE) is modified in a WSM\\ with tilted Weyl\ncones in comparison with its behavior in a normal metal and how a valley\npolarization can be detected using MOKE. We study both the Faraday\n(longitudinal) and Voigt (transverse) configurations for light incident on a\nsemi-infinite WSM surface with no Fermi arcs. We use a minimal model of a WSM\nwith four tilted Weyl nodes related by mirror and time-reversal symmetry. In\nthe Voigt configuration, a large peak of the Kerr angle occurs at the plasmon\nfrequency. We show that the blueshift in frequency of this peak with increasing\nmagnetic field is a signature of the chiral anomaly in the MOKE."
    },
    {
        "anchor": "Non-Hermitian higher-Order Weyl semimetal with surface diabolic points: Higher-order topology in non-Hermitian (NH) systems has recently become one\nof the most promising and rapidly developing fields in condensed matter\nphysics. Many distinct phases that were not present in the Hermitian\nequivalents are shown in these systems. In this work, we examine how\nhigher-order Weyl semimetals are impacted by NH perturbation. We identify a new\ntype of topological semimetal, i.e., non-Hermitian higher-order Weyl semimetal\n(NHHOWS) with surface diabolic points. We demonstrate that in such an NHHOWS,\nnew exceptional points inside the bulk can be created and annihilated,\ntherefore allowing us to manipulate their number. At the boundary, these\nexceptional points are connected through unique surface states with diabolic\npoints and hinge states. For specific system parameters, the surface of NHHOWS\nbehaves as a Dirac phase with linear dispersion or a Luttinger phase with a\nquadratic dispersion, thus paving a way for Dirac-Luttinger switching. Finally,\nwe employ the biorthogonal technique to reinstate the standard bulk boundary\ncorrespondence for NH systems and compute the topological invariants. The\nobtained quantized biorthogonal Chern number and quadruple moment topologically\nprotect the unique surface and hinge states, respectively.",
        "positive": "Optimizing the photothermoelectric effect in graphene: Among its many uses, graphene shows significant promise for optical and\noptoelectronic applications. In particular, devices based on the\nphotothermoelectric effect (PTE) in graphene can offer a strong and fast\nphotoresponse with high signal-to-noise ratio while consuming minimal power. In\nthis work we discuss how to optimize the performance of graphene PTE\nphotodetectors by tuning the light confinement, device geometry, and material\nquality. This study should prove useful for the design of devices using the PTE\nin graphene, with applications including optical sensing, data communications,\nmulti-gas sensing, and others."
    },
    {
        "anchor": "Effect of inter-edge Coulomb interactions on transport through a point\n  contact in a \u03bd= 5/2 quantum Hall state: We study transport across a point contact separating two line junctions in a\n\\nu = 5/2 quantum Hall system. We analyze the effect of inter-edge Coulomb\ninteractions between the chiral bosonic edge modes of the half-filled Landau\nlevel (assuming a Pfaffian wave function for the half-filled state) and of the\ntwo fully filled Landau levels. In the presence of inter-edge Coulomb\ninteractions between all the six edges participating in the line junction, the\nstable fixed point corresponds to a point contact which is neither fully opaque\nnor fully transparent. Remarkably, this fixed point represents a situation\nwhere the half-filled level is fully transmitting, while the two filled levels\nare completely backscattered; hence the fixed point Hall conductance is given\nby G_H = {1/2} e^2/h. We predict the non-universal temperature power laws by\nwhich the system approaches the stable fixed point from the two unstable fixed\npoints corresponding to the fully connected case (G_H = {5/2} e^2/h) and the\nfully disconnected case (G_H = 0).",
        "positive": "Decoherence of two entangled spin qubits coupled to an interacting\n  sparse nuclear spin bath: application to nitrogen vacancy centers: We consider pure dephasing of Bell states of electron spin qubits interacting\nwith a sparse bath of nuclear spins. Using the newly developed two-qubit\ngeneralization of cluster correlation expansion method, we calculate the spin\necho decay of $|\\Psi\\rangle$ and $|\\Phi\\rangle$ states for various interqubit\ndistances. Comparing the results with calculations in which dephasing of each\nqubit is treated independently, we identify signatures of influence of common\npart of the bath on the two qubits. At large interqubit distances, this common\npart consists of many nuclei weakly coupled to both qubits, so that decoherence\ncaused by it can be modeled by considering multiple uncorrelated sources of\nnoise (clusters of nuclei), each of them weakly affecting the qubits.\nConsequently, the resulting genuinely two-qubit contribution to decoherence can\nbe described as being caused by classical Gaussian noise. On the other hand,\nfor small interqubit distances the common part of the environment contains\nclusters of spins that are strongly coupled to both qubits, and their\ncontribution to two-qubit dephasing has visibly non-Gaussian character. We show\nthat one van easily obtain information about non-Gaussianity of environmental\nnoise affecting the qubits from the comparison of dephasing of $|\\Psi\\rangle$\nand $|\\Phi\\rangle$ Bell states. Numerical results are obtained for two nitrogen\nvacancy centers interacting with a bath of $^{13}$C nuclei of natural\nconcentration, for which we obtain that Gaussian description of correlated part\nof environmental noise starts to hold for centers separated by about 3 nm."
    },
    {
        "anchor": "Turbulent fronts of quantum detonation in molecular magnets: Dipolar-controlled quantum deflagration going over into quantum detonation in\nthe elongated Mn_12 Ac molecular magnet in a strong transverse field has been\nconsidered within the full 3d model. It is shown that within the dipolar window\naround tunneling resonances the deflagration front is non-flat. With increasing\nbias, dipolar instability makes the front turbulent, while its speed reaches\nsonic values, that is a signature of detonation.",
        "positive": "Optical absorption in semiconductor quantum dots: Nonlocal effects: The optical absorption of a single spherical semiconductor quantum dot in an\nelectrical field is studied taking into account the nonlocal coupling between\nthe field of the light and the polarizability of the semiconductor. These\nnonlocal effects lead to a small size anf field dependent shift and broadening\nof the excitonic resonance which may be of interest in future high precision\nexperiments."
    },
    {
        "anchor": "One-dimensional semirelativity for electrons in carbon nanotubes: It is shown that the band structure of single-wall semiconducting carbon\nnanotubes (CNT) is analogous to relativistic description of electrons in\nvacuum, with the maximum velocity $u$= $10^8$cm/s replacing the light velocity.\nOne-dimensional semirelativistic kinematics and dynamics of electrons in CNT is\nformulated. Two-band k.p Hamiltonian is employed to demonstrate that electrons\nin CNT experience a Zitterbewegung (trembling motion) in absence of external\nfields. This Zitterbewegung should be observable much more easily in CNT than\nits analogue for free relativistic electrons in vacuum.",
        "positive": "AC voltage effects on indirect excitons in a coupled quantum-well pair: The objective of this work is to numerically integrate in space and time the\neffective-mass Schrodinger equation for an excitonic wave packet in a coupled\nquantum-well system under a time-dependent electric field. Taking as a starting\npoint a time-dependent Hartree potential, we derive the nonlinear dynamical\nevolution of the excitonic wave function. We found that the system resonant\ncondition can be modified owing to the reaction field generated by a charge\ndynamically trapped in the quantum-well pair. As a result, this study raises a\nbroader question: is it possible to create an electrostatic trap for indirect\nexcitons at high ac frequencies? We conclude there is a possibility of having\nanother kind of terahertz electromagnetic radiation emerging from an excitonic\ntrap."
    },
    {
        "anchor": "Coherent states and their superpositions (cat states) in\n  microwave-induced resistance oscillations: We report a novel theoretical approach on the microwave-induced resistance\noscillations based on the coherent states of the quantum harmonic oscillator.\nWe first obtain an expression for the coherent states of driven-quantum\nharmonic oscillators that are used, in the model of microwaveinduced electron\norbits, to calculate magnetoresistance under radiation. Thus, we find that the\nprinciple of minimum uncertainty of coherent states, involving time and energy,\nis at the heart of photo-oscillations and zero resistance states. Accordingly,\nwe are able to explain important experimental evidence of this remarkable\neffect. Such as the physical origin of oscillations, their periodicity with the\ninverse of the magnetic field, their peculiar minima and maxima positions and\nthe existence of zero resistance states. We apply our theory to the case of\nultra-high mobility samples where we appeal to the principle of quantum\nsuperposition of coherent states and obtain that Schrodinger cat states (even\nand odd coherent states) are key to explain magnetoresistance at these extreme\nmobilities. With them we explain the, experimentally obtained,\nmagnetoresistance resonance peak shift to a magnetic field where the cyclotron\nfrequency equals half the radiation frequency. This effect is similar to the\none described in quantum optics as a second harmonic generation process. We\nalso explain the magnetoresistance collapse, that take place in the dark and\nwith light. This effect is known as giant negative magnetoresistance. We\ngeneralize our results to study the case of a three-component or triangular\nSchrodinger cat state.",
        "positive": "Topological invariant for generic 1D time reversal symmetric\n  superconductors in class DIII: A one dimensional time reversal symmetric topological superconductor\n(symmetry class DIII) features a single Kramers pair of Majorana bound states\nat each of its ends. These holographic quasiparticles are non-Abelian anyons\nthat obey Ising-type braiding statistics. In the special case where an\nadditional U(1) spin rotation symmetry is present, this state can be understood\nas two copies of a Majorana wire in symmetry class D, one copy for each spin\nblock. We present a manifestly gauge invariant construction of the topological\ninvariant for the generic case, i.e., in the absence of any additional\nsymmetries like spin rotation symmetry. Furthermore, we show how the presence\nof inversion symmetry simplifies the calcuation of the topological invariant.\nThe proposed scheme is suitable for the classification of both interacting and\ndisordered systems and allows for a straightforward numerical evaluation of the\ninvariant since it does not rely on fixing a continuous phase relation between\nBloch functions. Finally, we apply our method to compute the topological phase\ndiagram of a Rashba wire with competing s-wave and p-wave superconducting\npairing terms."
    },
    {
        "anchor": "Broadband Microwave Spectroscopy for Two-Dimensional Material Systems: In recent years, interesting materials have emerged which are only available\nas micron-scale flakes, and whose novel physics might be better understood\nthrough broadband microwave spectroscopy; examples include twisted bilayer\ngraphene [1], 2D materials in which many-body phases are observed [2], and\nartificial lattices for analog quantum simulations [3]. Most previous\ntechniques are unfortunately not sensitive for flakes below mm lateral sizes.\nWe propose a simple technique which does not require sophisticated sample\npreparation nor Ohmic contact and show through theory and simulations that one\nwill be able to qualitatively measure spectral features of interest, and\nquantitatively measure the frequency-dependent complex conductivity.",
        "positive": "Conductance fluctuations and disorder induced $\u03bd=0$ quantum Hall\n  plateau in topological insulator nanowires: Clean topological insulators exposed to a magnetic field develop Landau\nlevels accompanied by a nonzero Hall conductivity for the infinite slab\ngeometry. In this work we consider the case of disordered topological insulator\nnanowires and find, in contrast, that a zero Hall plateau emerges within a\nbroad energy window close to the Dirac point. We numerically calculate the\nconductance and its distribution for a statistical ensemble of disordered\nnanowires, and use the conductance fluctuations to study the dependence of the\ninsulating phase on system parameters, such as the nanowire length, disorder\nstrength and the magnetic field."
    },
    {
        "anchor": "Electron-phonon scattering in topological insulators: We formulate and apply a theory of electron-phonon interactions for the\nsurface state of a strong topological insulator. Phonons are modelled using an\nisotropic elastic continuum theory with stress-free boundary conditions and\ninteract with the Dirac surface fermions via the deformation potential. We\ndiscuss the temperature dependence of the quasi-particle lifetime in\nphotoemission and of the surface resistivity.",
        "positive": "Nuclear wave function interference in single-molecule electron transport: It is demonstrated that non-equilibrium vibrational effects are enhanced in\nmolecular devices for which the effective potential for vibrations is sensitive\nto the charge state of the device. We calculate the electron tunneling current\nthrough a molecule accounting for the two simplest qualitative effects of the\ncharging on the nuclear potential for vibrational motion: a shift (change in\nthe equilibrium position) and a distortion (change in the vibrational\nfrequency). The distortion has two important effects: firstly, it breaks the\nsymmetry between the excitation spectra of the two charge states. This gives\nrise to new transport effects which map out changes in the current-induced\nnon-equilibrium vibrational distribution with increasing bias voltage.\nSecondly, the distortion modifies the Franck-Condon factors for electron\ntunneling. Together with the spectral asymmetry this gives rise to pronounced\nnuclear wave function interference effects on the electron transport. For\ninstance nuclear-parity forbidden transitions lead to differential conductance\nanti-resonances, which are stronger than those due to allowed transitions. For\nspecial distortion and shift combinations a coherent suppression of transport\nbeyond a bias voltage threshold is possible."
    },
    {
        "anchor": "Theoretical condition for switching the magnetization in a\n  perpendicularly magnetized ferromagnet via the spin Hall effect: A theoretical formula is derived for the threshold current to switch a\nperpendicular magnetization in a ferromagnet by the spin Hall effect. The\nnumerical simulation of the Landau-Lifshitz-Gilbert equation indicates that\nmagnetization switching is achieved when the steady-state solution of the\nmagnetization in the presence of the current is outside an energetically\nunstable region. Based on the numerical result, an analytical theory deriving\nthe threshold current is developed by focusing on the first-order perturbation\nto the unstable state. The analytical formula clarifies that the magnitude of\nthe magnetic field applied to the current direction should be larger than 15\\%\nof the perpendicular magnetic anisotropy field, and the current is less than\nthe derived threshold value.",
        "positive": "Relaxation times and charge conductivity of silicene: We investigate the transport and single particle relaxation times of silicene\nin the presence of neutral and charged impurities. The static charge\nconductivity is studied using the semiclassical Boltzmann formalism when the\nspin-orbit interaction is taken into account. The screening is modeled within\nThomas-Fermi and random phase approximations. We show that the transport\nrelaxation time is always longer than the single particle one. Easy electrical\ncontrollability of both carrier density and band gap in this buckled\ntwo-dimensional structure makes it a suitable candidate for several electronic\nand optoelectronic applications. In particular, we observe that the dc charge\nconductivity could be easily controlled through an external electric field, a\nvery promising feature for applications as electrical switches and transistors.\nOur findings would be qualitatively valid for other buckled honeycomb lattices\nof the same family, such as germanine and stanine."
    },
    {
        "anchor": "Temperature-dependent electron microscopy study of Au thin films on Si\n  (100) with and without native oxide layer as barrier at the interface: Real time electron microscopy observation on morphological changes in gold\nnano structures deposited on Si (100) surfaces as a function of annealing\ntemperatures has been reported. Two types of interfaces with the substrate\nsilicon were used prior to gold thin film deposition: (i) without native oxide\nand on ultra-clean reconstructed Si surfaces and (ii) with native oxide covered\nSi surfaces. For a \\approx 2.0 nm thick Au films deposited on reconstructed\nSi(100) surfaces using molecular beam epitaxy method under ultra high vacuum\nconditions, aligned four-fold symmetric nanogold silicide structures formed at\nrelatively lower temperatures (compared with the one with native oxide at the\ninterface). For this system, 82% of the nanostructures were found to be nano\nrectangles like structures with an average length \\approx 27 nm and aspect\nratio of 1.13 at \\approx 700{\\deg}C. For \\approx 5.0 nm thick Au films\ndeposited on Si (100) surface with native oxide at the interface, formation of\nrectangular structures were observed at higher temperatures (\\approx 850{\\deg}\nC). At these high temperatures, desorption of the gold silicide followed the\nsymmetry of the substrate. Native oxide at the interface was found to act like\na barrier for the inter-diffusion phenomena. Structural characterization was\ncarried out using advanced electron microscopy methods.",
        "positive": "Perfect one-dimensional chiral states in biased twisted bilayer graphene: We theoretically study the electronic structure of small-angle twisted\nbilayer graphene with a large potential asymmetry between the top and bottom\nlayers. We show that the emergent helical states known to appear on the\ntriangular AB-BA domain boundary do not actually form a percolating network,\nbut instead they provide independent, perfect one-dimensional channels\npropagating in three different directions. Using the continuum-model\nHamiltonian, we demonstrate that an applied bias causes two well-defined energy\nwindows which contain sparsely distributed one-dimensional channels. The origin\nof these energy windows can be understood using a two-band model of the\nintersecting electron and hole bands of single layer graphene. We also use the\ntight-binding model to implement the lattice deformations in twisted bilayer\ngraphene, and discuss the effect of lattice relaxation on the one-dimensional\nchannels."
    },
    {
        "anchor": "All-electrical detection of spin dynamics in magnetic antidot lattices\n  by the inverse spin Hall effect: The understanding of spin dynamics in laterally confined structures on\nsub-micron length scales has become a significant aspect of the development of\nnovel magnetic storage technologies. Numerous ferromagnetic resonance\nmeasurements, optical characterization by Kerr microscopy and Brillouin light\nscattering spectroscopy and x-ray studies were carried out to detect the\ndynamics in patterned magnetic antidot lattices. Here, we investigate\nOersted-field driven spin dynamics in rectangular Ni80Fe20/Pt antidot lattices\nwith different lattice parameters by electrical means and compare them to\nmicromagnetic simulations. When the system is driven to resonance, a dc voltage\nacross the length of the sample is detected that changes its sign upon field\nreversal, which is in agreement with a rectification mechanism based on the\ninverse spin Hall effect. Furthermore, we show that the voltage output scales\nlinearly with the applied microwave drive in the investigated range of powers.\nOur findings have direct implications on the development of engineered\nmagnonics applications and devices.",
        "positive": "Electron-electron attraction in an engineered electromechanical system: Two electrons in a quantum dot repel each other: their interaction can be\ncharacterized by a positive interaction energy. From the theory of\nsuperconductivity, we also know that mechanical vibrations of the crystal\nlattice can make the electron-electron interaction attractive. Analogously, if\na quantum dot interacts with a mechanical degree of freedom, the effective\ninteraction energy can be negative; that is, the electron-electron interaction\nmight be attractive. In this work, we propose and theoretically study an\nengineered electromechanical system that exhibits electron-electron attraction:\na quantum dot suspended on a nonlinear mechanical resonator, tuned by a bottom\nand a top gate electrode. We focus on the example of a dot embedded in a\nsuspended graphene ribbon, for which we identify conditions for\nelectron-electron attraction. Our results suggest the possibility of electronic\ntransport via tunneling of packets of multiple electrons in such devices,\nsimilar to that in superconducting nanostructures, but without the use of any\nsuperconducting elements."
    },
    {
        "anchor": "The influence of the elementary charge on the canonical quantization of\n  LC -circuits: In this paper one deals with the quantization of mesoscopic LC-circuits under\nthe influence of an external time dependent voltage. The canonically conjugated\nvariables, such as given by the electric charge and the magnetic flux, get\nestablished by resorting to the hamiltonian equations of motion provided by\nboth Faraday and Kirchhoff laws . This time the discretization of the electric\ncharge is accounted for, so that magnetic flux operators one looks for should\nproceed in terms of discrete derivatives. However, the flux operators one deals\nwitg are not Hermitian, which means that subsequent symmetrizations are in\norder. The eigenvalues characterizing such operators cab be readily established\nin terms of twisted boundary conditions. Besides the discrete Schrodinger\nequation with nearest-neighbor hoppings, a nontrivial next nearest neighbor\ngeneralization has also been established. Such issues open the way to the\nderivation of persistent currents in terms of effective k-dependent\nHamiltonians. Handling the time dependent voltage within the nearest neighbor\ndescription leadsto the derivation of dynamic localization effects in L-ring\nconfigurations, such as discussed before by Dunlap and Kenkre The onset of the\nmagnetic flux quantum has also been discussed in some more detail.",
        "positive": "Multilayer approximation for a confined fluid in a slit pore: A simple Lennard-Jones fluid confined in a slit nanopore with hard walls is\nstudied on the basis of a multilayer structured model. Each layer is\nhomogeneous and parallel to the walls of the pore. The Helmholtz energy of this\nsystem is constructed following van der Waals-like approximations, with the\nadvantage that the model geometry permits to obtain analytical expressions for\nthe integrals involved. Being the multilayer system in thermodynamic\nequilibrium, a system of non-linear equations is obtained for the densities and\nwidths of the layers. A numerical solution of the equations gives the density\nprofile and the longitudinal pressures. The results are compared with Monte\nCarlo simulations and with experimental data for Nitrogen, showing very good\nagreement."
    },
    {
        "anchor": "Valley filter and valley valve in graphene: It is known that the lowest propagating mode in a narrow ballistic ribbon of\ngraphene may lack the twofold valley degeneracy of higher modes. Depending on\nthe crystallographic orientation of the ribbon axis, the lowest mode mixes both\nvalleys or lies predominantly in a single valley (chosen by the direction of\npropagation). We show, using a tight-binding model calculation, that a\nnonequilibrium valley polarization can be realized in a sheet of graphene, upon\ninjection of current through a ballistic point contact with zigzag edges. The\npolarity can be inverted by local application of a gate voltage to the point\ncontact region. Two valley filters in series may function as an\nelectrostatically controlled ``valley valve'', representing a\nzero-magnetic-field counterpart to the familiar spin valve.",
        "positive": "Domain Wall in a Quantum Anomalous Hall Insulator as a Magnetoelectric\n  Piston: We theoretically study the magnetoelectric coupling in a quantum anomalous\nHall insulator state induced by interfacing a dynamic magnetization texture to\na topological insulator. In particular, we propose that the quantum anomalous\nHall insulator with a magnetic configuration of a domain wall, when contacted\nby electrical reservoirs, acts as a magnetoelectric piston. A moving domain\nwall pumps charge current between electrical leads in a closed circuit, while\napplying an electrical bias induces reciprocal domain-wall motion. This\npiston-like action is enabled by a finite reflection of charge carriers via\nchiral modes imprinted by the domain wall. Moreover, we find that, when\ncompared with the recently discovered spin-orbit torque-induced domain-wall\nmotion in heavy metals, the reflection coefficient plays the role of an\neffective spin-Hall angle governing the efficiency of the proposed electrical\ncontrol of domain walls. Quantitatively, this effective spin-Hall angle is\nfound to approach a universal value of $2$, providing an efficient scheme to\nreconfigure the domain-wall chiral interconnects for possible memory and logic\napplications."
    },
    {
        "anchor": "Long-wavelength emergent phonons in skyrmion crystals distorted by\n  exchange anisotropy and tilted magnetic fields: Skyrmion crystals (SkX) are periodic alignment of magnetic skyrmions, i.e., a\ntype of topologically protected spin textures. Compared with ordinary crystals,\nthey can be drastically deformed under anisotropic effects because they are\ncomposed of field patterns whose deformation does not cause any bond-breaking.\nThis exotic ductility of SkX bring about great tunability of its collective\nexcitations called emergent phonons, which are vital for magnonics application.\nThe question is how to quantitatively determine the emergent phonons of\ndistorted SkX. Here we systematically study the long wavelength emergent\nphonons of SkX distorted by (a) a negative exchange anisotropy, and (b) a\ntilted magnetic field. In both cases, deformation and structural transitions of\nSkX thoroughly influence the frequency, anisotropy of vibrational pattern and\ndispersion relation, and coupling between lattice vibration and in-lattice\nvibration for all modes. Tilted magnetic fields are very effective in tuning\nthe emergent phonons, such that all modes except the Goldstone mode can be\nexcited by AC magnetic fields when a tilted bias field is presented.",
        "positive": "Theory of the spatial structure of non-linear lasing modes: A self-consistent integral equation is formulated and solved iteratively\nwhich determines the steady-state lasing modes of open multi-mode lasers. These\nmodes are naturally decomposed in terms of frequency dependent biorthogonal\nmodes of a linear wave equation and not in terms of resonances of the cold\ncavity. A one-dimensional cavity laser is analyzed and the lasing mode is found\nto have non-trivial spatial structure even in the single-mode limit. In the\nmulti-mode regime spatial hole-burning and mode competition is treated exactly.\nThe formalism generalizes to complex, chaotic and random laser media."
    },
    {
        "anchor": "Theoretical investigation of the applicability of the Meservey-Tedrow\n  technique to the surface states of topological insulators: The spin polarization of topological surface states is of high interest for\npossible applications in spintronics. At present, the only technique capable to\nmeasure the surface state spin texture is spin and angle resolved photoemission\nspectroscopy (SARPES). However, values reported by SARPES differed strongly. An\nestablished technique to measure the spin polarization of ferromagnetic\nmaterials is the so-called Meservey-Tedrow technique, which is based on spin\ndependent tunneling from a superconducting electrode to a ferromagnet. Here, we\ntheoretically investigate how the Meservey-Tedrow technique can be adapted to\ntopological insulators. We demonstrate that with a specific device geometry it\nis possible to determine the in-plane component of the spin polarization of\ntopological surface states. More complex device geometries can access the full\nmomentum dependence of the spin polarization. We also show that it is possible\nto extract the spin-flip scattering rate of surface electrons with the same\ndevices.",
        "positive": "Observation of a broadband Lamb shift in an engineered quantum system: The shift of energy levels owing to broadband electromagnetic vacuum\nfluctuations, the Lamb shift, has been pivotal in the development of quantum\nelectrodynamics and in understanding atomic spectra. Currently, small energy\nshifts in engineered quantum systems are of paramount importance owing to the\nextreme precision requirements in applications such as quantum computing.\nHowever, without a tunable environment it is challenging to resolve the Lamb\nshift in its original broadband case. Consequently, the observations in other\nthan atomic systems are limited to environments comprised of narrow-band modes.\nHere, we observe a broadband Lamb shift in high-quality superconducting\nresonators, a scenario also accessing static shifts inaccessible in Lamb's\nexperiment. We measure a continuous change of several megahertz in the\nfundamental resonator frequency by externally tuning the coupling strength of\nthe engineered broadband environment which is based on hybrid\nnormal-metal--superconductor tunnel junctions. Our results may lead to improved\ncontrol of dissipation in high-quality engineered quantum systems and open new\npossibilities for studying synthetic open quantum matter using this hybrid\nexperimental platform."
    },
    {
        "anchor": "Hartree-Fock Theory of Skyrmions in Quantum Hall Ferromagnets: We report on a study of the charged-skyrmion or spin-texture excitations\nwhich occur in quantum Hall ferromagnets near odd Landau level filling factors.\nParticle-hole symmetry is used to relate the spin-quantum numbers of charged\nparticle and hole excitations and neutral particle-hole pair excitations.\nHartree-Fock theory is used to provide quantitative estimates of the energies\nof these excitations and their dependence on Zeeman coupling strength, Landau\nlevel quantum numbers, and the thicknesses of the two-dimensional electron\nlayers. For the case of $\\nu$ near three we suggest the possibility of first\norder phase transitions with increasing Zeeman coupling strength from a many\nskyrmion state to one with many maximally spin-polarized quasiparticles.",
        "positive": "Micromagnetic modelling of magnetic domain walls and domains in\n  cylindrical nanowires: Magnetic cylindrical nanowires are very fascinating objects where the curved\ngeometry allows many novel magnetic effects and a variety of non-trivial\nmagnetic structures. Micromagnetic modelling plays an important role in\nrevealing the magnetization distribution in magnetic nanowires, often not\naccessible by imaging methods with sufficient details. Here we review the\nmagnetic properties of the shape anisotropy-dominated nanowires and the\nnanowires with competing shape and magnetocrystalline anisotropies, as revealed\nby micromagnetic modelling. We discuss the variety of magnetic walls and\nmagnetic domains reported by micromagnetic simulations in cylindrical\nnanowires. The most known domain walls types are the transverse and vortex\n(Bloch point) domain walls and the transition between them is materials and\nnanowire diameter dependent. Importantly, the field or current-driven domain\nwalls in cylindrical nanowires can achieve very high velocities. In recent\nsimulations of nanowires with larger diameter the skyrmion tubes are also\nreported. In nanowires with large saturation magnetization the core of these\ntubes may form a helicoidal ('corkscrew') structure. The topology of the\nskyrmion tubes play an important role in the pinning mechanism, discussed here\non the example of FeCo modulated nanowires. Other discussed examples include\nthe influence of antinotches ('bamboo' nanowires) on the remanent magnetization\nconfigurations for hcp Co and FeCo nanowires and Co-Ni multisegmented\nnanowires."
    },
    {
        "anchor": "Thickness dependent enhancement of the polar magneto-optic Kerr effect\n  in Co magnetoplasmonic nanostructures: Large surface plasmon polariton assisted enhancement of the magneto-optical\nactivity has been observed in the past, through spectral measurements of the\npolar Kerr rotation in Co hexagonal antidot arrays. Here, we report a strong\nthickness dependence, which is unexpected given that the Kerr effect is\nconsidered a surface sensitive phenomena. The maximum Kerr rotation was found\nto be -0.66 degrees for a 100 nm thick sample. This thickness is far above the\ntypical optical penetration depth of a continuous Co film, demonstrating that\nin the presence of plasmons the critical lengthscales are dramatically altered,\nand in this case extended. We therefore establish that the plasmon enhanced\nKerr effect does not only depend on the in-plane structuring of the sample, but\nalso on the out-of-plane geometrical parameters, which is an important\nconsideration in magnetoplasmonic device design.",
        "positive": "Nano-structured thin films growth in stochastic plasma-condensate\n  systems: We derive the stochastic model of plasma-condensate systems by taking into\naccount anisotropy in transference of adatoms between neighbor layers and by\nintroducing fluctuations of adsorbate flux. We show, that by varying the\nfluctuation's intensity on can govern dynamics of pattern formation on\nintermediate layer of multi-layer plasma-condensate system. It is shown that\nthe morphology of the growing surface, type of surface structures and their\nlinear size can be controlled by the intensity of the adsorbate flux\nfluctuations."
    },
    {
        "anchor": "Frequency comb from a single driven nonlinear nanomechanical mode: Phononic frequency combs have been attracting an increasing attention both as\na qualitatively new type of nonlinear phenomena in vibrational systems and from\nthe point of view of applications. It is commonly believed that at least two\nmodes must be involved in generating a comb. In this paper we demonstrate that\na comb can be generated by a single nanomechanical mode driven by a resonant\nmonochromatic drive. The comb emerges where the drive is still weak, so that\nthe anharmonic part of the mode potential energy remains small. We relate the\neffect to a negative nonlinear friction induced by the resonant drive, which\nmakes the vibrations at the drive frequency unstable. We directly map the\ntrajectories of the emerging oscillations in the rotating frame and show how\nthese oscillations lead to the frequency comb in the laboratory frame. The\nresults go beyond nanomechanics and suggest a qualitatively new approach to\ngenerating tunable frequency combs in single-mode vibrational systems.",
        "positive": "Computational Design of Chemical Nanosensors: Metal Doped Carbon\n  Nanotubes: We use computational screening to systematically investigate the use of\ntransition metal doped carbon nanotubes for chemical gas sensing. For a set of\nrelevant target molecules (CO, NH3, H2S) and the main components of air (N2,\nO2, H2O), we calculate the binding energy and change in conductance upon\nadsorption on a metal atom occupying a vacancy of a (6,6) carbon nanotube.\nBased on these descriptors, we identify the most promising dopant candidates\nfor detection of a given target molecule. From the fractional coverage of the\nmetal sites in thermal equilibrium with air, we estimate the change in the\nnanotube resistance per doping site as a function of the target molecule\nconcentration assuming charge transport in the diffusive regime. Our analysis\npoints to Ni-doped nanotubes as candidates for CO sensors working under typical\natmospheric conditions."
    },
    {
        "anchor": "Nanotube mechanical resonators with quality factors of up to 5 million: Carbon nanotube mechanical resonators have attracted considerable interest\nbecause of their small mass, the high quality of their surface, and the\npristine electronic states they host. However, their small dimensions result in\nfragile vibrational states that are difficult to measure. Here we observe\nquality factors $Q$ as high as $5\\times10^6$ in ultra-clean nanotube resonators\nat a cryostat temperature of 30 mK, where we define $Q$ as the ratio of the\nresonant frequency over the linewidth. Measuring such high quality factors\nrequires both employing an ultra-low noise method to detect minuscule\nvibrations rapidly, and carefully reducing the noise of the electrostatic\nenvironment. We observe that the measured quality factors fluctuate because of\nfluctuations of the resonant frequency. The quality factors we measure are\nrecord high; they are comparable to the highest $Q$ reported in mechanical\nresonators of much larger size, a remarkable result considering that reducing\nthe size of resonators is usually concomitant with decreasing quality factors.\nThe combination of ultra-low size and very large $Q$ offers new opportunities\nfor ultra-sensitive detection schemes and quantum optomechanical experiments.",
        "positive": "Chemical potential and compressibility of quantum Hall bilayer excitons: This paper considers a system of two parallel quantum Hall layers with total\nfilling factor $0$ or $1$. When the distance between the layers is small\nenough, electrons and holes in opposite layers form inter-layer excitons, which\nhave a finite effective mass and interact via a dipole-dipole potential.\nResults are presented for the chemical potential $\\mu$ of the resulting bosonic\nsystem as a function of the exciton concentration $n$ and the interlayer\nseparation $d$. Both $\\mu$ and the interlayer capacitance have an unusual\nnonmonotonic dependence on $d$, owing to the interplay between an increasing\ndipole moment and an increasing effective mass with increasing $d$. A phase\ntransition between superfluid and Wigner crystal phases is shown to occur at $d\n\\propto n^{-1/10}$. Results are derived first via simple intuitive arguments,\nand then verified with more careful analytic derivations and numeric\ncalculations."
    },
    {
        "anchor": "Collective magnetic dynamics in artificial spin ice probed by AC\n  susceptibility: We report on the study of the thermal dynamics of square artificial spin ice,\nprobed by means of temperature and frequency dependent AC susceptibility.\nPronounced influence of the inter-island coupling strength was found on the\nfrequency response of the samples. Through the subsequent analysis of the\nfrequency- and coupling-dependent freezing temperatures, we discuss the\nphenomenological parameters obtained in the framework of Vogel-Fulcher-Tammann\nlaw in terms of the samples microscopic features. The high sensitivity and\nrobust signal to noise ratio of AC susceptibility validates the latter as a\npromising and simple experimental technique for resolving the dynamics and\ntemperature driven dynamics crossovers for the case of artificial spin ice.",
        "positive": "Trion photoluminescence and trion stability in atomically thin\n  semiconductors: The optical response of doped monolayer semiconductors is governed by trions,\ni.e. photoexcited electron-hole pairs bound to doping charges. While their\nphotoluminescence (PL) signatures have been identified in experiments, a\nmicroscopic model consistently capturing bright and dark trion peaks is still\nlacking. In this work, we derive a generalized trion PL formula on a\nquantum-mechanical footing, considering direct and phonon-assisted\nrecombination mechanisms. We show the trion energy landscape in WSe$_2$ by\nsolving the trion Schr\\\"odinger equation. We reveal that the mass imbalance\nbetween equal charges results in less stable trions exhibiting a small binding\nenergy and, interestingly, a large energetic offset from exciton peaks in PL\nspectra. Furthermore, we compute the temperature-dependent PL spectra for n-\nand p-doped monolayers and predict yet unobserved signatures originating from\ntrions with an electron at the $\\Lambda$ point. Our work presents an important\nstep towards a microscopic understanding of the internal structure of trions\ndetermining their stability and optical fingerprint."
    },
    {
        "anchor": "A Theory of a Self-Assembling Electrovariable Smart Mirror: A theory describing the forces governing the self-assembly of nanoparticles\nat the solid-liquid interface is developed. In the process, new theoretical\nresults are derived to describe the effect that the field penetration of a\npoint-like particle, into an electrode, has on the image potential energy, and\npair interaction energy profiles at the electrode-electrolyte interface. The\napplication of the theory is demonstrated for gold and ITO electrode systems,\npromising materials for novel colour-tuneable electrovariable smart mirrors and\nmirror-window devices respectively. Model estimates suggest that\nelectrovariability is attainable in both systems and will act as a guide for\nfuture experiments. Lastly, the generalisability of the theory towards\nelectrovariable, nanoplasmonic systems suggests that it may contribute towards\nthe design of intelligent metamaterials with programmable properties.",
        "positive": "Observation of second sound in graphite at temperatures above 100 K: Wavelike thermal transport in solids, referred to as second sound, has until\nnow been an exotic phenomenon limited to a handful of materials at low\ntemperatures. This has restricted interest in its occurrence and in its\npotential applications. Through time-resolved optical measurements of thermal\ntransport on 5-20 {\\mu}m length scales in graphite, we have made direct\nobservations of second sound at temperatures above 100 K. The results are in\nqualitative agreement with ab initio calculations that predict wavelike phonon\nhydrodynamics on ~ 1-{\\mu}m length scale up to almost room temperature. The\nresults suggest an important role of second sound in microscale transient heat\ntransport in two-dimensional and layered materials in a wide temperature range."
    },
    {
        "anchor": "Optical Direct Write of Dolan--Niemeyer-Bridge Junctions for Transmon\n  Qubits: We characterize highly coherent transmon qubits fabricated with a\ndirect-write photolithography system. Multi-layer evaporation and oxidation\nallows us to change the critical current density by reducing the effective\ntunneling area and increasing the barrier thickness. Surface treatments before\nresist application and again before evaporation result in high coherence\ndevices. With optimized surface treatments we achieve energy relaxation $T_1$\ntimes in excess of $80\\ \\mu$s for three dimensional transmon qubits with\nJosephson junction lithographic areas of 2 $\\mu\\mathrm{m}^2$.",
        "positive": "Functionalization mediates heat transport in graphene nanoflakes: Self-heating is a severe problem for high-power microelectronic devices.\nGraphene and few-layer graphene have attracted tremendous attention for heat\nremoval thanks to their extraordinarily high in-plane thermal conductivity.\nHowever, this high thermal conductivity undergoes severe degradations caused by\nthe contact with the substrate and the functionalization-induced point defects.\nHere we show that thermal management of a micro heater can be substantially\nimproved via introduction of alternative heat-escaping channels implemented\nwith graphene-based film covalently bonded to functionalized graphene oxide\nthrough silane molecules. Theoretical and experimental results demonstrate a\ncounter-intuitive enhancement of the thermal conductivity of such a\ngraphene-based film. This increase in the in-plane thermal conductivity of\nsupported graphene is accompanied by an improvement on the graphene-substrates\nthermal contact. Using infrared thermal imaging, we demonstrate that the\ntemperature of the hotspots can be lowered by 12 $^o$C in transistors operating\nat 130 W mm$^{-2}$ , which corresponds to half of an order-of-magnitude\nincrease in the device lifetime. Ab initio and molecular dynamics simulations\nreveal that the functionalization constrains the cross-plane scattering of low\nfrequency phonons, which in turn enhances in-plane heat conduction of the\nbonded graphene film by recovering the long flexural phonon lifetime."
    },
    {
        "anchor": "The quenching of compressible edge states around antidots: We provide a systematic quantitative description of the edge state structure\naround a quantum antidot in the integer quantum Hall regime. The calculations\nfor spinless electrons within the Hartree approximation reveal that the widely\nused Chklovskii et al. electrostatic description greatly overestimates the\nwidths of the compressible strips; the difference between these approaches\ndiminishes as the size of the antidot increases. By including spin effects\nwithin density functional theory in the local spin-density approximation, we\ndemonstrate that the exchange interaction can suppress the formation of\ncompressible strips and lead to a spatial separation between the spin-up and\nspin-down states. As the magnetic field increases, the outermost compressible\nstrip, related to spin-down states starts to form. However, in striking\ncontrast to quantum wires, the innermost compressible strip (due to spin-up\nstates) never develops for antidots.",
        "positive": "Electron-phonon coupling of Fe-adatom electron states on MgO/Ag(100): We study the strength of the electron-phonon interaction on Fe single adatoms\non MgO/Ag(100) based on many-body \\textit{ab-initio} spin collinear\ncalculations. In particular, we analyze the relative importance of the\nsubstrate and, among other results, we conclude that the interface electron\nstate of Ag(100) plays a prominent role in determining the electron-phonon\ncoupling of localized Fe electron states. The analysis of the hybridization of\nthe adatom with the substrate reveals qualitative differences for even or odd\ncoverages of MgO, affecting significantly the spectral structure and strength\nof the electron-phonon coupling. Our calculations indicate that the\nelectron-phonon interaction is very strong for $\\le$~1 layers of MgO, while it\nis sharply suppressed for larger coverages, a trend that is consistent with\nrecent experimental findings."
    },
    {
        "anchor": "Photogalvanic effect in HgTe/CdTe topological insulator due to edge-bulk\n  optical transitions: We study theoretically 2D HgTe/CdTe quantum well topological insulator (TI)\nilluminated by circularly polarized light with frequencies higher than the\ndifference between the equilibrium Fermi level and the bottom of the conduction\nband (THz range). We show that electron-hole asymmetry results in\nspin-dependent electric dipole transitions between edge and bulk states, and we\npredict an occurrence of a circular photocurrent. If the edge state is\ntunnel-coupled to a conductor, then the photocurrent can be detected by\nmeasuring an electromotive force (EMF) in the conductor, which is proportional\nto the photocurrent.",
        "positive": "Helical edge resistance introduced by charge puddles: We study the influence of electron puddles created by doping of a 2D\ntopological insulator on its helical edge conductance. A single puddle is\nmodeled by a quantum dot tunnel-coupled to the helical edge. It may lead to\nsignificant inelastic backscattering within the edge because of the long\nelectron dwelling time in the dot. We find the resulting correction to the\nperfect edge conductance. Generalizing to multiple puddles, we assess the\ndependence of the helical edge resistance on temperature and doping level, and\ncompare it with recent experimental data."
    },
    {
        "anchor": "Heat transfer between two metals through subnanometric vacuum gaps: We theoretically investigate the heat transfer between two metals across a\nvacuum gap in extreme near-field regime by quantifying the relative\ncontribution of electrons, phonons and photons. We show that electrons play a\ndominant role in the heat transfer between two metals at subnanometric distance\nsubject to a temperature gradient. Moreover, we demonstrate that this effect is\ndramatically amplified in the presence of an applied bias voltage. These\nresults could pave the way to novel strategies for thermal management and\nenergy conversion in extreme near-field regime.",
        "positive": "Chirality-induced zigzag domain wall in in-plane magnetized ultrathin\n  films: The domain structure in in-plane magnetized Fe/Ni/W(110) films is\ninvestigated using spin-polarized low-energy electron microscopy. A novel\ntransition of the domain wall shape from a zigzag-like pattern to straight is\nobserved as a function of the film thickness, which is triggered by the\ntransition of the domain wall type from out-of-plane chiral wall to in-plane\nN\\'eel wall. The contribution of the Dzyaloshinskii-Moriya interaction to the\nwall energy is proposed to explain the transition of the domain wall shape,\nwhich is supported by Monte-Carlo simulations."
    },
    {
        "anchor": "Effects of Vanadium Doping on the Optical Response and Electronic\n  Structure of WS$_{2}$ Monolayers: Two-dimensional dilute magnetic semiconductors has been recently reported in\nsemiconducting transition metal dichalcogenides by the introduction of\nspin-polarized transition metal atoms as dopants. This is the case of\nvanadium-doped WS$_2$ and WSe$_2$ monolayers, which exhibits a ferromagnetic\nordering even above room temperature. However, a broadband characterization of\ntheir electronic band structure and its dependence on vanadium concentration is\nstill lacking. Therefore, here we perform power-dependent photoluminescence,\nresonant four-wave mixing, and differential reflectance spectroscopy to study\nthe optical transitions close to the A exciton energy of vanadium-doped WS$_2$\nmonolayers with distinct concentrations. Instead of a single A exciton peak,\nvanadium-doped samples exhibit two photoluminescence peaks associated with\ntransitions to occupied and unoccupied bands. Moreover, resonant Raman\nspectroscopy and resonant second-harmonic generation measurements revealed a\nblueshift in the B exciton but no energy change in the C exciton as vanadium is\nintroduced in the monolayers. Density functional theory calculations showed\nthat the band structure is sensitive to the Hubbard \\(U\\) correction for\nvanadium and several scenarios are proposed to explain the two\nphotoluminescence peaks around the A exciton energy region. Our work provides\nthe first broadband optical characterization of these two-dimensional dilute\nmagnetic semiconductors, shedding light on the novel electronic features of\nWS$_{2}$ monolayers which are tunable by the vanadium concentration.",
        "positive": "Dynamic exchange via spin currents in acoustic and optical modes of\n  ferromagnetic resonance in spin-valve structures: Two ferromagnetic layers magnetically decoupled by a thick normal metal\nspacer layer can be, nevertheless, dynamically coupled via spin currents\nemitted by the spin-pump and absorbed through the spin-torque effects at the\nneighboring interfaces. A decrease of damping in both layers due to a partial\ncompensation of the angular momentum leakage in each layer was previously\nobserved at the coincidence of the two ferromagnetic resonances. In case of\nnon-zero magnetic coupling, such a dynamic exchange will depend on the mutual\nprecession of the magnetic moments in the layers. A difference in the linewidth\nof the resonance peaks is expected for the acoustic and optical regimes of\nprecession. However, the interlayer coupling hybridizes the resonance responses\nof the layers and therefore can also change their linewidths. The interplay\nbetween the two mechanisms has never been considered before. In the present\nwork, the joint influence of the hybridization and non-local damping on the\nlinewidth has been studied in weakly coupled NiFe/CoFe/Cu/CoFe/MnIr spin-valve\nmultilayers. It has been found that the dynamic exchange by spin currents is\ndifferent in the optical and acoustic modes, and this difference is dependent\non the interlayer coupling strength. In contrast to the acoustic precession\nmode, the dynamic exchange in the optical mode works as an additional damping\nsource. A simulation in the framework of the Landau-Lifshitz-Gilbert formalism\nfor two ferromagnetic layers coupled magnetically and by spin currents has been\ndone to separate the effects of the non-local damping from the resonance modes\nhybridization. In our samples both mechanisms bring about linewidth changes of\nthe same order of magnitude, but lead to a distinctly different angular\nbehavior. The obtained results are relevant for a broad class of coupled\nmagnetic multilayers with ballistic regime of the spin transport."
    },
    {
        "anchor": "Superfluid weight bounds from symmetry and quantum geometry in flat\n  bands: Flat-band superconductivity has theoretically demonstrated the importance of\nband topology to correlated phases. In two dimensions, the superfluid weight,\nwhich determines the critical temperature through the\nBerezinksii-Kosterlitz-Thouless criteria, is bounded by the Fubini-Study metric\nat zero temperature. We show this bound is nonzero within flat bands whose\nWannier centers are obstructed from the atoms - even when they have identically\nzero Berry curvature. Next, we derive general lower bounds for the superfluid\nweight in terms of momentum space irreps in all 2D space groups, extending the\nreach of topological quantum chemistry to superconducting states. We find that\nthe bounds can be naturally expressed using the formalism of real space\ninvariants (RSIs) that highlight the separation between electronic and atomic\ndegrees of freedom. Finally, using exact Monte Carlo simulations on a model\nwith perfectly flat bands and strictly local obstructed Wannier functions, we\nfind that an attractive Hubbard interaction results in superconductivity as\npredicted by the RSI bound beyond mean-field. Hence, a nonzero superfluid\nweight constitutes a nontrivial bulk property that distinguishes obstructed\nbands from trivial bands in the presence of interactions.",
        "positive": "Holey topological thermoelectrics: We study the thermoelectric properties of three-dimensional topological\ninsulators with many holes (or pores) in the bulk. We show that at high density\nof these holes the thermoelectric figure of merit ZT can be large due to the\ncontribution of the conducting surfaces and the suppressed phonon thermal\nconductivity. The maximum efficiency can be tuned by an induced gap in the\nsurface states dispersion through tunneling or external magnetic fields. The\nlarge values of ZT, much higher than unity for reasonable parameters, make this\nsystem a strong candidate for applications in heat management of nanodevices,\nespecially at low temperatures."
    },
    {
        "anchor": "Nonlinear wave-packet dynamics in a disordered medium: In this article we develop an effective theory of pulse propagation in a\nnonlinear and disordered medium. The theory is formulated in terms of a\nnonlinear diffusion equation. Despite its apparent simplicity this equation\ndescribes novel phenomena which we refer to as \"locked explosion\" and\n\"diffusive\" collapse. In this sense the equation can serve as a paradigmatic\nmodel, that can be applied to such distinct physical systems as laser beams\npropagating in disordered photonic crystals or Bose-Einstein condensates\nexpanding in a disordered environment.",
        "positive": "Valley-dependent resonant tunneling through double magnetic barriers in\n  suspended graphene: We theoretically investigate the effects of strain-induced pseudomagnetic\nfields on the transmission probability and the ballistic conductance for Dirac\nfermion transport in suspended graphene. We show that resonant tunneling\nthrough double magnetic barriers can be tuned by strain in the suspended\nregion. The valley-resolved transmission peaks are apparently distinguishable\nowing to the sharpness of the resonant tunneling. With the specific strain, the\nresonant tunneling is completely suppressed for Dirac fermions occupying the\none valley, but the resonant tunneling exists for the other valley. The\nvalley-filtering effect is expected to be measurable by strain engineering. The\nproposed system can be used to fabricate a graphene valley filter with the\nlarge valley polarization almost 100%."
    },
    {
        "anchor": "Wigner crystallization in the two electron quantum dot: Wigner crystallization can be induced in a quantum dot by increasing the\neffective electron-electron interaction through a decrease of the electron\ndensity or by the application of a strong magnetic field. We show that the\nground state in both cases is very similar but the energy scales are very\ndifferent and therefore also the dynamics.",
        "positive": "Anomalous Hydrodynamics in One Dimensional Electronic Fluid: We construct multi-mode viscous hydrodynamics for one dimensional spinless\nelectrons. Depending on the scale, the fluid has six (shortest lengths), four\n(intermediate, exponentially broad regime), or three (asymptotically long\nscales) hydrodynamic modes. Interaction between hydrodynamic modes leads to\nanomalous scaling of physical observables and waves propagating in the fluid.\nIn a four-mode regime, all modes are ballistic and acquire KPZ-like broadening\nwith asymmetric power-law tails. \"Heads\" and \"tails\" of the waves contribute\nequally to thermal conductivity, leading to $\\omega^{-1/3}$ scaling of its real\npart. In a three-mode regime, the system is in the universality class of\nclassical viscous fluid[9,24]. Self-interaction of the sound modes results in\nKPZ-like shape, while the interaction with the heat mode results in asymmetric\ntails. The heat mode is governed by Levy flight distribution, whose power-law\ntails give rise to $\\omega^{-1/3}$ scaling of heat conductivity."
    },
    {
        "anchor": "Dynamics of the effective mass and the anomalous velocity in\n  two-dimensional lattices: The semiclassical description of the dynamics of wave packets in periodic\npotentials and subject to an applied force relies on the concepts of effective\nmass and anomalous transport. This picture is valid if the force changes slowly\nin time and space, so that the particle described by the wave packet has time\nto respond according to the properties of the lattice. We analyze the dynamical\ncorrections to this picture when a uniform force is suddenly applied,\nidentifying separate corrections to the usual group and anomalous velocities.\nWe find approximate semianalytical expressions for generalized \"dynamical\"\ngroup and anomalous velocities, and the associated accelerations. We use a\ntwo-dimensional optical lattice with finite Berry curvature to illustrate the\nsemianalytical approximation in a regime where the dynamical corrections are\nsignificant, suggesting the possibility of experiments to detect them; we\ncompare the results with a full numerical solution, showing excellent agreement\nfor weak forces.",
        "positive": "Landau-Zener tunneling in 2D periodic structures in the presence of a\n  gauge field II: Electric breakdown: We analyze dynamics of a quantum particle in a square lattice in the Hall\nconfiguration beyond the single-band approximation. For vanishing gauge\n(magnetic) field this dynamics is defined by the inter-band Landau-Zener\ntunneling, which is responsible for the phenomenon known as the electric\nbreakdown. We show that in the presence of a gauge field this phenomenon is\nabsent, at least, in its common sense. Instead, the Landau-Zener tunneling\nleads to appearance of a finite current which flows in the direction orthogonal\nto the vector of a potential (electric) field."
    },
    {
        "anchor": "Exchange-spring behavior in bimagnetic CoFe2O4/CoFe2 nanocomposite: In this work we report a study of the magnetic behavior of ferrimagnetic\noxide CoFe2O4 and ferrimagnetic oxide/ferromagnetic metal CoFe2O4/CoFe2\nnanocomposites. The latter compound is a good system to study hard\nferrimagnet/soft ferromagnet exchange coupling. Two steps were used to\nsynthesize the bimagnetic CoFe2O4/CoFe2 nanocomposites: (i) first preparation\nof CoFe2O4 nanoparticles using the a simple hydrothermal method and (ii) second\nreduction reaction of cobalt ferrite nanoparticles using activated charcoal in\ninert atmosphere and high temperature. The phase structures, particle sizes,\nmorphology, and magnetic properties of CoFe2O4 nanoparticles have been\ninvestigated by X-Ray diffraction (XRD), Mossbauer spectroscopy (MS),\ntransmission electron microscopy (TEM), and vibrating sample magnetometer (VSM)\nwith applied field up to 3.0 kOe at room temperature and 50K. The mean diameter\nof CoFe2O4 particles is about 16 nm. Mossbauer spectra reveal two sites for\nFe3+. One site is related to Fe in an octahedral coordination and the other one\nto the Fe3+ in a tetrahedral coordination, as expected for a spinel crystal\nstructure of CoFe2O4. TEM measurements of nanocomposite show the formation of a\nthin shell of CoFe2 on the cobalt ferrite and indicate that the nanoparticles\nincrease to about 100 nm. The magnetization of nanocomposite showed hysteresis\nloop that is characteristic of the exchange spring systems. A maximum energy\nproduct (BH)max of 1.22 MGOe was achieved at room temperature for CoFe2O4/CoFe2\nnanocomposites, which is about 115% higher than the value obtained for CoFe2O4\nprecursor. The exchange-spring interaction and the enhancement of product\n(BH)max in nanocomposite CoFe2O4/CoFe2 have been discussed.",
        "positive": "Description of Quantum Beams Using a Stationary Incoherent Superposition\n  of Wave Packets: An original entity is defined to study quantum beams of conserved particles.\nThe beam is described as a Stationary Incoherent Superposition of Wave packets\n(SISOW). Mean values are time-independent confirming that the SISOW describes a\nstationary flux of particles. The SISOW is a general entity that contains the\nHamiltonian eigenstates as a particular limit. The decomposition of the SISOW\ninto wave packets provides intrinsic dynamic information which is not\naccessible from Hamiltonian eigenstates. The SISOW provides and adequate\nframework to study mesoscopic systems"
    },
    {
        "anchor": "Spin-mediated dissipation and frequency shifts of a cantilever at\n  milliKelvin temperatures: We measure the dissipation and frequency shift of a magnetically coupled\ncantilever in the vicinity of a silicon chip, down to $25$ mK. The dissipation\nand frequency shift originates from the interaction with the unpaired\nelectrons, associated with the dangling bonds in the native oxide layer of the\nsilicon, which form a two dimensional system of electron spins. We approach the\nsample with a $3.43$ $\\mu$m-diameter magnetic particle attached to an ultrasoft\ncantilever, and measure the frequency shift and quality factor as a function of\ntemperature and the distance. Using a recent theoretical analysis [J. M. de\nVoogd et al., arXiv:1508.07972 (2015)] of the dynamics of a system consisting\nof a spin and a magnetic resonator, we are able to fit the data and extract the\nrelaxation time $T_1=0.39\\pm0.08$ ms and spin density $\\sigma=0.14\\pm0.01$\nspins per nm$^2$. Our analysis shows that at temperatures $\\leq500$ mK magnetic\ndissipation is an important source of non-contact friction.",
        "positive": "Electronic structure, charge transfer, and intrinsic luminescence of\n  gadolinium oxide nanoparticles: Experiment and theory: The cubic (c) and monoclinic (m) polymorphs of Gd2O3 were studied using the\ncombined analysis of several materials science techniques - X-ray diffraction\n(XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy\n(XPS), and photoluminescence (PL) spectroscopy. Density functional theory (DFT)\nbased calculations for the samples under study were performed as well. The\ncubic phase of gadolinium oxide (c-Gd2O3) synthesized using a precipitation\nmethod exhibits spheroidal-like nanoclusters with well-defined edges assembled\nfrom primary nanoparticles with an average size of 50 nm, whereas the\nmonoclinic phase of gadolinium oxide (m-Gd2O3) deposited using explosive\npyrolysis has a denser structure compared with natural gadolinia. This phase\nalso has a structure composed of three-dimensional complex agglomerates without\nclear-edged boundaries that are ~21 nm in size plus a cubic phase admixture of\nonly 2 at. % composed of primary edge-boundary nanoparticles ~15 nm in size.\nThese atomic features appear in the electronic structure as different defects\n([Gd...O-OH] and [Gd...O-O]) and have dissimilar contributions to the\ncharge-transfer processes among the appropriate electronic states with\nambiguous contributions in the Gd 5p - O 2s core-like levels in the valence\nband structures. The origin of [Gd...O-OH] defects found by XPS was\nwell-supported by PL analysis. The electronic and atomic structures of the\nsynthesized gadolinias calculated using DFT were compared and discussed on the\nbasis of the well-known joint OKT-van der Laan model, and good agreement was\nestablished."
    },
    {
        "anchor": "Negative length orbits in normal-superconductor billiard systems: The Path-Length Spectra of mesoscopic systems including diffractive\nscatterers and connected to superconductor is studied theoretically. We show\nthat the spectra differs fundamentally from that of normal systems due to the\npresence of Andreev reflection. It is shown that negative path-lengths should\narise in the spectra as opposed to normal system. To highlight this effect we\ncarried out both quantum mechanical and semiclassical calculations for the\nsimplest possible diffractive scatterer. The most pronounced peaks in the\nPath-Length Spectra of the reflection amplitude are identified by the routes\nthat the electron and/or hole travels.",
        "positive": "Magneto-optical coupling in whispering gallery mode resonators: We demonstrate that yttrium iron garnet microspheres support optical\nwhispering gallery modes similar to those in non-magnetic dielectric materials.\nThe direction of the ferromagnetic moment tunes both the resonant frequency via\nthe Voigt effect as well as the degree of polarization rotation via the Faraday\neffect. An understanding of the magneto-optical coupling in whispering gallery\nmodes, where the propagation direction rotates with respect to the\nmagnetization, is fundamental to the emerging field of cavity optomagnonics."
    },
    {
        "anchor": "Friedel oscillations in disordered quantum wires: Influence of e-e\n  interactions on the localization length: The Friedel oscillations caused due to an impurity located at one edge of a\ndisordered interacting quantum wire are calculated numerically. The electron\ndensity in the system's ground state is determined using the DMRG method, and\nthe Friedel oscillations data is extracted using the density difference between\nthe case in which the wire is coupled to an impurity and the case where the\nimpurity is uncoupled. We show that the power law decay of the oscillations\noccurring for an interacting clean 1D samples described by Luttinger liquid\ntheory, is multiplied by an exponential decay term due to the disorder. Scaling\nof the average Friedel oscillations by this exponential term collapses the\ndisordered samples data on the clean results. We show that the length scale\ngoverning the exponential decay may be associated with the Anderson\nlocalization length and thus be used as a convenient way to determine the\ndependence of the localization length on disorder and interactions. The\nlocalization length decreases as a function of the interaction strength, in\naccordance with previous predictions.",
        "positive": "SpinWaves in Ferromagnetic Dots 2D Honeycomb Lattice Stripes: In this work, the spin wave calculations were carried out using the\nHeisenberg Hamiltonian to study the allowed spin waves of zigzag and armchair\nedged stripes for ferromagnetic nanodots arrayed in a 2D honeycomb lattice\n\\cite{Selim2011}. The Hamiltonian is used to construct the $\\mathbf{E}$ matrix\nwhich encodes the exchange flow of magnons in the stripes. It is found that the\nallowed spin wave modes are the eigenvalues of the $\\mathbf{E}$ matrix and\ntherefore it is used to study the effects of the stripe width, edge exchange,\nthe edge uniaxial anisotropy, and impurities on the allowed spin waves of\nstripes. The obtained results almost coincide with the results of graphene\nnanoribbons described by tight binding Hamiltonian for electronic excitations.\nTherefore, we suggest the fabrication of the magnetic counterpart to graphene\nas a new technology in the field of spintronic devices and magnetic\napplications."
    },
    {
        "anchor": "Shear viscosity as a probe of nodal topology: Electronic materials can sustain a variety of unusual, but symmetry protected\ntouchings of valence and conduction bands, each of which is identified by a\ndistinct topological invariant. Well-known examples include linearly dispersing\npseudo-relativistic fermions in monolayer graphene, Weyl and nodal-loop\nsemimetals, biquadratic (bicubic) band touching in bilayer (trilayer) graphene,\nas well as mixed dispersions in multi-Weyl systems. Here we show that depending\non the underlying band curvature, the shear viscosity in the collisionless\nregime displays a unique power-law scaling with frequency at low temperatures,\nbearing the signatures of the band topology, which are distinct from the ones\nwhen the system resides at the brink of a topological phase transition into a\nband insulator. Therefore, besides the density of states (governing specific\nheat, compressibility) and dynamic conductivity, shear viscosity can be\ninstrumental to pin nodal topology in electronic materials.",
        "positive": "STM and DFT studies of CO2 adsorption on Cu(100)-O surface: We characterized CO2 adsorption and diffusion on the missing row\nreconstructed Cu(100)-O surface using a combination of scanning tunneling\nmicroscopy (STM) and density functional theory (DFT) calculations with\ndispersion. We deposited CO2 molecules in situ at 5K, which allowed us to\nunambiguously identify individual CO2 molecules and their adsorption sites.\nBased on a comparison of experimental and DFT-generated STM images, we find\nthat the CO2 molecules sit in between the O atoms in the missing row\nreconstructed Cu(100)-O surface. The CO2 molecules are easily perturbed by the\nSTM tip under typical imaging conditions, suggesting that the molecules are\nweakly bound to the surface. The calculated adsorption energy, vibrational\nmodes, and diffusion barriers of the CO2 molecules also indicate weak\nadsorption, in qualitative agreement with the experiments. A comparison of\ntunneling spectroscopy and DFT-calculated density of states shows that the\nprimary change near the Fermi level is associated with changes to the surface\nstates with negligible contribution from the CO2 molecular states."
    },
    {
        "anchor": "Fingerprints of Majorana bound states in Aharonov Bohm geometry: We study a ring geometry, coupled to two normal metallic leads, which has a\nMajorana bound state (MBS) embedded in one of its arm and is threaded by\nAharonov Bohm ($\\mathcal{A}\\mathcal{B}$) flux $\\phi$. We show that by varying\nthe $\\mathcal{AB}$ flux, the two leads go through resonance in an\nanti-correlated fashion while the resonance conductance is quantized to $2\ne^2/h$. We further show that such anti-correlation is completely absent when\nthe MBS is replaced by an Andreev bound state (ABS). Hence this\nanti-correlation in conductance when studied as a function of $\\phi$ provides a\nunique signature of the MBS which cannot be faked by an ABS. We contrast the\nphase sensitivity of the MBS and ABS in terms of tunneling conductances. We\nargue that the relative phase between the tunneling amplitude of the electrons\nand holes from either lead to the level (MBS or ABS), which is constrained to\n$0,\\pi$ for the MBS and unconstrained for the ABS, is responsible for this\ninteresting contrast in the $\\mathcal{AB}$ effect between the MBS and ABS.",
        "positive": "Breakdown of local convertibility through Majorana modes in a quantum\n  quench: The local convertibility of quantum states, measured by the R\\'enyi entropy,\nis concerned with whether or not a state can be transformed into another state,\nusing only local operations and classical communications. We found that in the\none-dimensional Kitaev chain with quenched chemical potential $\\mu$, the\nconvertibility between the state for $\\mu$ and that for $\\mu+\\delta\\mu$,\ndepends on the quantum phases of the system ($\\delta\\mu$ is a perturbation).\nThis is similar to the adiabatic case where the ground state is considered.\nSpecifically, when the quenched system has edge modes and the subsystem size\nfor the partition is much larger than the correlation length of the Majorana\nfermions which forms the edge modes, the quenched state is locally\ninconvertible. We give a physical interpretation for the result, based on\nanalyzing the interactions between the two subsystems for various partitions.\nOur work should help to better understand the many-body phenomena in\ntopological systems and also the entanglement properties in the Majorana\nfermionic quantum computation."
    },
    {
        "anchor": "Statistics of diffusive and localized fields in the vortex core: The statistics of the field structure in the vortex core surrounding phase\nsingularities in random wave fields are measured and calculated for diffusive\nand localized waves. Excellent agreement is found between experiment and\ntheory. The variation of phase with geometric angle is deterministic, depending\nonly upon the eccentricity of elliptical intensity contours, whose probability\ndistribution is shown to be universal. The distribution of vorticity is shown\nto reflect both the vorticity distribution in the Gaussian limit and the\nmesoscopic distribution of total transmission.",
        "positive": "Superconductivity in quantum-dot superlattices composed of quantum wire\n  networks: Based on calculations using the local density approximation, we propose\nquantum wire networks with square and plaquette type lattice structures that\nform quantum dot superlattices. These artificial structures are well described\nby the Hubbard model. Numerical analysis reveals a superconducting ground state\nwith transition temperatures $T_c$ of up to 90 mK for the plaquette, which is\nmore than double the value of 40 mK for the square lattice type and is\nsufficiently high to allow for the experimental observation of\nsuperconductivity."
    },
    {
        "anchor": "Ultra-Fast Stark-Induced Control of Polaritonic States: A laser pulse, several meV red-detuned from the excitonic line of a quantum\nwell, has been shown to induce an almost instantaneous and rigid shift of the\nlower and upper polariton branches. Here we demonstrate that through this\nshift, ultra-fast all-optical control of the polariton population in a\nsemiconductor microcavity should be achievable. In the proposed setup a Stark\nfield is used to bring the lower polariton branch in or out of resonance with a\nquasi-resonant continuous-wave laser, thereby favoring or inhibiting the\ninjection of polaritons into the cavity. Moreover we show that this technique\nallows for the implementation of optical switches with extremely high\nrepetition rates.",
        "positive": "Global biasing using a Hardware-based artificial Zeeman term in Spinwave\n  Ising Machines: A spinwave Ising machine (SWIM) is a newly proposed type of time-multiplexed\nhardware solver for combinatorial optimization that employs feedback coupling\nand phase sensitive amplification to map an Ising Hamiltonian into\nphase-binarized propagating spin-wave RF pulses in an Yttrium-Iron-Garnet (YIG)\nfilm. In this work, we increase the mathematical complexity of the SWIM by\nadding a global Zeeman term to a 4-spin MAX-CUT Hamiltonian using a continuous\nexternal electrical signal with the same frequency as the spin pulses and phase\nlocked with with one of the two possible states. We are able to induce\nferromagnetic ordering in both directions of the spin states despite\nantiferromagnetic pairwise coupling. Embedding a planar antiferromagnetic spin\nsystem in a magnetic field has been proven to increase the complexity of the\ngraph associated to its Hamiltonian and thus this straightforward\nimplementation helps explore higher degrees of complexity in this evolving\nsolver."
    },
    {
        "anchor": "Novel approach to Raman spectra of nanoparticles: In crystalline nanoparticles the Raman peak is downshifted with respect to\nthe bulk material and has asymmetric broadening. These effects are straightly\nrelated to the finite size of nanoparticles, giving the perspective to use the\nRaman spectroscopy as the size probe. By combining the dynamical matrix method\n(DMM) and the bond polarization model (BPM), we develop a new (DMM-BPM)\napproach to the description of Raman spectra for random arrays of\nnanoparticles. The numerical variant of this approach is suitable for the\ndescription of small particles, whereas its simplier to implement analytical\nversion allows to obtain the Raman spectra of arbitrary sized particles.\nFocusing on nanodiamond powders, the DMM-BPM theory is shown to fit the most\nrecent experimental data much better than the commonly used phonon confinement\nmodel (PCM), especially for small enough nanoparticles.",
        "positive": "Gate controlled photocurrent generation mechanisms in high-gain In2Se3\n  phototransistors: Photocurrent in photodetectors incorporating van der Waals materials is\ntypically produced by a combination of photocurrent generation mechanisms that\noccur simultaneously during operation. Because of this, response times in these\ndevices often yield to slower, high gain processes which cannot be turned off.\nHere we report on photodetectors incorporating the layered material In2Se3,\nwhich allow complete modulation of a high gain, photogating mechanism in the ON\nstate in favor of fast photoconduction in the OFF state. While photoconduction\nis largely gate independent, photocurrent from the photogating effect is\nstrongly modulated through application of a back gate voltage. By varying the\nback gate, we demonstrate control over the dominant mechanism responsible for\nphotocurrent generation. Furthermore, due to the strong photogating effect,\nthese direct-band gap, multi-layer phototransistors produce ultra-high gains of\n(9.8 +- 2.5) x 10^4 A/W and inferred detectivities of (3.3 +- 0.8) x 10^13\nJones, putting In2Se3 amongst the most sensitive 2D materials for\nphotodetection studied to date."
    },
    {
        "anchor": "Trial wave functions, molecular states, and ro-vibrational spectra in\n  the lowest Landau level: A universal description for bosons and fermions: Through the introduction of a class of appropriate translationally invariant\ntrial wave functions, we show that the strong correlations in the lowest Landau\nlevel (LLL) reflect in finite systems the emergence of intrinsic point-group\nsymmetries associated with rotations and vibrations of molecules formed through\nparticle localization. This molecular description is universal, being valid for\nboth bosons and fermions, for both the yrast and excited states of the LLL\nspectra, and for both low and high angular momenta. This physical picture is\nfundamentally different from the \"quantum-fluid\" one associated with\nJastrow-type trial functions.",
        "positive": "High performance Tunnel Field Effect Transistors based on in-plane\n  transition metal dichalcogenide heterojunctions: In-plane heterojunction tunnel field effect transistors based on monolayer\ntransition metal dichalcogenides are studied by means of self-consistent\nnon-equilibrium Green's functions simulations and an atomistic tight-binding\nHamiltonian. We start by comparing several heterojunctions before focusing on\nthe most promising ones, i.e WTe2-MoS2 and MoTe2-MoS2. The scalability of those\ndevices as a function of channel length is studied, and the influence of\nbackgate voltages on device performance is analysed. Our results indicate that,\nby fine-tuning the design parameters, those devices can yield extremely low\nsub-threshold swings (below 5mV/decade) and Ion/Ioff ratios higher than 1e8 at\na supply voltage of 0.3V, making them ideal for ultra-low power consumption."
    },
    {
        "anchor": "Manipulation of skyrmions in nanodisks with a current pulse and skyrmion\n  rectifier: A skyrmion in a nanosized disk of a chiral magnet can be used as a bit of\ninformation. To this end, it is desirable to control the creation and removal\nof a skyrmion only by currents without using external magnetic fields. Here we\npropose to create a skyrmion by applying a current pulse to a nanodisk. The\nskyrmion can be removed from the disk by applying a dc current. We show that\nthe dynamics of the created skyrmion can lead to a rectification effect, in\nwhich a dc voltage is generated by the motion of skyrmion in the presence of an\nac current.",
        "positive": "Ultrafast Momentum Imaging of Pseudospin-Flip Excitations in Graphene: The pseudospin of Dirac electrons in graphene manifests itself in a peculiar\nmomentum anisotropy for photo-excited electron-hole pairs. These interband\nexcitations are in fact forbidden along the direction of the light\npolarization, and are maximum perpendicular to it. Here, we use time- and\nangle-resolved photoemission spectroscopy to investigate the resulting\nunconventional hot carrier dynamics, sampling carrier distributions as a\nfunction of energy and in-plane momentum. We first show that the\nrapidly-established quasi-thermal electron distribution initially exhibits an\nazimuth-dependent temperature, consistent with relaxation through collinear\nelectron-electron scattering. Azimuthal thermalization is found to occur only\nat longer time delays, at a rate that depends on the substrate and the static\ndoping level. Further, we observe pronounced differences in the electron and\nhole dynamics in n-doped samples. By simulating the Coulomb- and\nphonon-mediated carrier dynamics we are able to disentangle the influence of\nexcitation fluence, screening, and doping, and develop a microscopic picture of\nthe carrier dynamics in photo-excited graphene. Our results clarify new aspects\nof hot carrier dynamics that are unique to Dirac materials, with relevance for\nphoto-control experiments and optoelectronic device applications."
    },
    {
        "anchor": "Energy transport and fluctuations in small conductors: The Landauer-B\\\"uttiker formalism provides a simple and insightful way for\ninvestigating many phenomena in mesoscopic physics. By this approach we derive\ngeneral formulas for the energy properties and apply them to the basic setups.\nOf particular interest are the noise properties. We show that energy current\nfluctuations can be induced by zero-point fluctuations and we discuss the\nimplications of this result.",
        "positive": "Chemical and Crystallographic Characterization of the Tip Apex in\n  Scanning Probe Microscopy: The apex atom of a W scanning probe tip reveals a non-spherical charge\ndistribution as probed by a CO molecule bonded to a Cu(111) surface [Welker et\nal. Science, 336, 444 (2012)]. Three high-symmetry images were observed and\nrelated to three low-index crystallographic directions of the W bcc crystal.\nOpen questions remained, however, including the verification that the tip was\nindeed W-terminated, and whether this method can be easily applied to\ndistinguish other atomic species. In this work, we investigate bulk Cu and Fe\ntips. In both cases we can associate our data with the fcc (Cu) and bcc (Fe)\ncrystal structures. A model is presented, based on the partial filling of d\norbitals, to relate the AFM images to the angular orientation of the tip\nstructure."
    },
    {
        "anchor": "Spin relaxation in CdTe quantum dots with a single Mn atom: We have investigated spin relaxation times in CdTe quantum dots doped with a\nsingle Mn atom, a prototype of a system where the interaction between a single\ncharge carrier and a single spin takes place. A theoretical model that was used\nincludes the electron-Mn spin exchange interaction responsible for mixing of\nthe states of different spin in the basic Hamiltonian and electron-phonon\ninteraction as a perturbation responsible for transitions between the states.\nIt was found that the dominant electron-phonon interaction mechanism\nresponsible for spin relaxation is the interaction with acoustic phonons\nthrough deformation potential. Electron and Mn spin relaxation times at room\ntemperature take values in the range from microseconds at a magnetic field of\n0.5 T down to nanoseconds at a magnetic field of 10 T and become three orders\nof magnitude larger at cryogenic temperatures. It was found that electron\nspin-orbit interaction has a negligible effect on spin relaxation times, while\nthe changes in the position of the Mn atom within the dot and in the dot\ndimensions can change the spin relaxation times by up to one order of\nmagnitude.",
        "positive": "Topology Optimization of Surface-enhanced Raman Scattering Substrates: Surface-enhanced Raman spectroscopy is a powerful and versatile sensing\nmethod with a detection limit down to the single molecule level. In this\narticle, we demonstrate how topology optimization (TopOpt) can be used for\ndesigning surface enhanced Raman scattering (SERS) substrates adhering to\nrealistic fabrication constraints. As an example, we experimentally\ndemonstrated a SERS enhancement factor of 5*10e4 for the 604 cm-1 Raman line of\nrhodamine 6G using metal nanostructures with a critical dimension of 20 nm. We\nthen show that, by relaxing the fabrication constraints, TopOpt may be used to\ndesign SERS substrates with orders of magnitude larger enhancement factor. The\nresults validate topology optimization as an effective method for engineering\nnanostructures with optimal performance and fabrication tolerance."
    },
    {
        "anchor": "$p_{x}+ip_{y}$ superfluid from s-wave interactions of fermionic cold\n  atoms: Two-dimensional ($p_{x}+ip_{y}$) superfluids/superconductors offer a\nplayground for studying intriguing physics such as quantum teleportation,\nnon-Abelian statistics, and topological quantum computation. Creating such a\nsuperfluid in cold fermionic atom optical traps using p-wave Feshbach resonance\nis turning out to be challenging. Here we propose a method to create a\n$p_{x}+ip_{y}$ superfluid directly from an s-wave interaction making use of a\ntopological Berry phase, which can be artificially generated. We discuss ways\nto detect the spontaneous Hall mass current, which acts as a diagnostic for the\nchiral p-wave superfluid.",
        "positive": "Field-Driven Self-Assembly of Magnetite Nanoparticles Investigated Using\n  Small-Angle Neutron Scattering: The magnetic-field-induced assembly of magnetic nanoparticles (NPs) provides\na unique and flexible strategy in the design and the fabrication of functional\nnanostructures and devices. We have investigated the field-driven self-assembly\nof core-shell magnetite NPs dispersed in toluene by means of in situ small\nangle neutron scattering (SANS). The form factor of the core-shell NPs was\ncharacterized and analyzed using SANS with polarized neutrons. Large-scale\naggregation of magnetite NPs has formed above 0.02 T as indicated by very-small\nangle neutron scattering measurements. Three-dimensional long-range ordered\nsuperlattice of magnetite NPs was revealed under the application of moderate\nmagnetic field. The crystal structure of the superlattice has been identified\nas a face-centered cubic one."
    },
    {
        "anchor": "Local electronic properties of single wall nanotube circuits measured by\n  conducting-tip AFM: We use conducting-tip atomic force microscopy (AFM) to measure local\nelectronic properties of single wall carbon nanotube (SWNT) circuits on\ninsulating substrates. When a voltage is applied to the tip and AFM feedback is\nused to position the tip, images formed from the tip-sample tunnel current have\nsingle tube resolution (near 1 nm diameter), more than an order of magnitude\nbetter than simultaneously acquired topographic AFM images. By finding points\nwhere the tip-sample current is zero, it is possible to measure the\nelectrochemical potential within the circuit, again with nanometer resolution.\nSuch measurements provide compelling evidence that nanotubes within a bundle\nhave only weak electronic coupling. Finally the AFM tip is used as a local\nelectrostatic gate, and the gating action can be correlated with the structure\nof the SWNT bundle sample. This technique should be useful for a broad range of\ncircuits containing SWNTs and other molecules.",
        "positive": "Resistance Fluctuations in Composite Fermion State near Landau Level\n  Filling Factor $\u03bd= 1/2$ in A Square Quantum Well: We have studied the magnetotransport near Landau level filling factor $\\nu =\n1/2$ in a GaAs-Al0.3Ga0.7As square quantum well (width 35 nm) in magnetic field\nup to 42 T and in a temperature range between 50 mK and 1.5 K. In low\ntemperatures T < 200 mK, the Rxx exhibits a deep, strongly\ntemperature-dependent minimum centered at $\\nu = 1/2$. The concomitant Rxy is\nnot strictly linear with magnetic field (B) and the first derivative of Rxy\nwith respect to B shows a sharp cusp at $\\nu = 1/2$, indicating a non-classical\nHall effect. We verify these characteristics are being single-layer origin by\napplying an in-plane magnetic field or electrostatic gates. The data may signal\nfrustrations in the composite fermion state towards $\\nu = 1/2$ pairing in the\nquantum well where the electron layer thickness far exceeds the magnetic\nlength."
    },
    {
        "anchor": "Quasibound States and Evidence for a Spin 1 Kondo Effect in Asymmetric\n  Quantum Point Contacts: Linear conductance below $2e^2/h$ shows resonance peaks in highly asymmetric\nquantum point contacts (QPCs). As the channel length increases, the number of\npeaks also increases. At the same time, differential conductance exhibits zero\nbias anomalies (ZBAs) in correspondence with every other peak in the linear\nconductance. This even odd effect, observable in the longer channels, is\nconsistent with the formation of quasi-localized states within the QPC. In rare\ncases, triple peaks are observed, indicating the formation of a spin one Kondo\neffect when the electron filling number is even. Changing the gate voltage\ntunes this spin triplet to a singlet which exhibits no ZBA. The triple-peak\nprovides the first evidence suggestive of a spin singlet triplet transition in\na QPC, and the presence of a ferromagnetic spin interaction between electrons.",
        "positive": "Conductance Quantization in Graphene Nanoribbons: We report the experimental observation of conductance quantization in\ngraphene nanoribbons, where 1D transport subbands are formed due to the lateral\nquantum confinement. We show that this quantization in graphene nanoribbons can\nbe observed at temperatures as high as 80 K and channel lengths as long as 1.7\n$\\mu$m. The observed quantization is in agreement with that predicted by\ntheoretical calculations."
    },
    {
        "anchor": "Water desorption and re-adsorption on epitaxial graphene studied by SPM: We demonstrate the temperature-mediated and completely reversible process of\ndesorption-readsorption of water on a few layers of epitaxial graphene on a\n4H-SiC(0001) substrate. We show that under ambient conditions water forms solid\nstructures on top of the second and third layers of graphene. In the case of\nstrained or highly defective graphene domains, these features produce strongly\ncorrelated and reproducible patterns, implying importance of the underlying\ndefects for the initial stages of water adsorption. Hydrophobicity increases\nwith number of graphene layers. Evolution of the water layer as a function of\ntemperature is accompanied by a significant (two-fold) change of the absolute\nsurface potential difference between one and two layers of graphene. In situ\nobservation of water evolution during heating also potentially provides a\ndirect method for measurement of the heat adsorption on the nanoscale.",
        "positive": "Steady-state spin densities and currents: This article reviews steady-state spin densities and spin currents in\nmaterials with strong spin-orbit interactions. These phenomena are intimately\nrelated to spin precession due to spin-orbit coupling which has no equivalent\nin the steady state of charge distributions. The focus will be initially on\neffects originating from the band structure. In this case spin densities arise\nin an electric field because a component of each spin is conserved during\nprecession. Spin currents arise because a component of each spin is continually\nprecessing. These two phenomena are due to independent contributions to the\nsteady-state density matrix, and scattering between the conserved and\nprecessing spin distributions has important consequences for spin dynamics and\nspin-related effects in general. In the latter part of the article extrinsic\neffects such as skew scattering and side jump will be discussed, and it will be\nshown that these effects are also modified considerably by spin precession.\nTheoretical and experimental progress in all areas will be reviewed."
    },
    {
        "anchor": "Magnetoresistance in a High Mobility Two-Dimensional Electron Gas: In a high mobility two-dimensional electron gas (2DEG) in a GaAs/AlGaAs\nquantum well we observe a strong magnetoresistance. In lowering the electron\ndensity the magnetoresistance gets more pronounced and reaches values of more\nthan 300%. We observe that the huge magnetoresistance vanishes for increasing\nthe temperature. An additional density dependent factor is introduced to be\nable to fit the parabolic magnetoresistance to the electron-electron\ninteraction correction.",
        "positive": "Sustainable spin current in the time-dependent Rashba system: The generation of spin current and spin polarization in 2DEG Rashba system is\nconsidered, in which the spin-orbital coupling (SOC) is modulated by an ac gate\nvoltage. By using non-Abelian gauge field method, we show the presence of an\nadditional electric field. This field induces a spin current generated even in\nthe presence of impurity scattering and is related to the time-modulation of\nthe Rashba SOC strength. In addition, the spin precession can be controlled by\nmodulating the modulation frequency of the Rashba SOC strength. It is shown\nthat at high modulation frequency, the precessional motion is suppressed so\nthat the electron spin polarization can be sustained in the 2DEG"
    },
    {
        "anchor": "Equal-Spin Andreev Reflection in Junctions of Spin-Resolved Quantum Hall\n  Bulk State and Spin-Singlet Superconductor: The recent development of superconducting spintronics has revealed the\nspin-triplet superconducting proximity effect from a spin-singlet\nsuperconductor into a spin-polarized normal metal. In addition recently\nsuperconducting junctions using semiconductors are in demand for highly\ncontrolled experiments to engineer topological superconductivity. Here we\nreport experimental observation of Andreev reflection in junctions of\nspin-resolved quantum Hall (QH) states in an InAs quantum well and the\nspin-singlet superconductor NbTi. The measured conductance indicates a sub-gap\nfeature and two peaks on the outer side of the sub-gap feature in the QH\nplateau-transition regime increases. The observed structures can be explained\nby considering transport with Andreev reflection from two channels, one\noriginating from equal-spin Andreev reflection intermediated by spin-flip\nprocesses and second arising from normal Andreev reflection. This result\nindicates the possibility to induce the superconducting proximity gap in the\nthe QH bulk state, and the possibility for the development of superconducting\nspintronics in semiconductor devices.",
        "positive": "Conductance anomalies in a one-dimensional quantum contact: Short length quantum wires (quantum contacts) exhibit a conductance structure\nat the value of conductance close to 0.7 \\times 2e^2/h. The structure is also\ncalled the conductance anomaly. In longer contacts the structure evolves to the\nlower values of conductance. We demonstrate that this structure is related to\nthe development of charge density waves within the contact. This is a precursor\nfor Wigner crystallization. Many-body Hartree-Fock calculations of conductance\nare performed. The results are in agreement with experimental data."
    },
    {
        "anchor": "Spin-memory loss induced by bulk spin-orbit coupling at\n  ferromagnet/heavy-metal interfaces: A spin current through a ferromagnet/heavy-metal interface may shrink due to\nthe spin-flip at the interface, resulting in the spin-memory loss. Here we\npropose a mechanism of the spin-memory loss. In contrast to other mechanisms\nbased on interfacial spin-orbit coupling, our mechanism is based on the bulk\nspin-orbit coupling in a heavy-metal. We demonstrate that the bulk spin-orbit\ncoupling induces the entanglement between the spin and orbital degrees of\nfreedom and this spin-orbital entanglement can give rise to sizable spin-flip\nat the interface even when the interfacial spin-orbit coupling is weak. Our\nmechanism emphasizes crucial roles of the atomic orbital degree of freedom and\ninduces the strong spin-memory loss near band crossing points between bands of\ndifferent orbital characters.",
        "positive": "Magnon topological transition in skyrmion crystal: We study the magnon spectrum in skyrmion crystal formed in thin ferromagnetic\nfilms with Dzyalosinskii-Moria interaction in presence of magnetic field.\nFocusing on two low-lying observable magnon modes and employing stereographic\nprojection method, we develop a theory demonstrating a topological transition\nin the spectrum. Upon the increase of magnetic field, the gap between two\nmagnon bands closes, with the ensuing change in the topological character of\nboth bands. This phenomenon of gap closing, if confirmed in magnetic resonance\nexperiments, may deserve further investigation by thermal Hall conductivity\nexperiments."
    },
    {
        "anchor": "Propagation of collective surface plasmons in 1D periodic ionic\n  structure: The propagation of the collective surface plasmons, called\nplasmon-polaritons, in infinite equidistant ionic sphere chain has been\nanalyzed. The ideal cancellation of irradiative losses of these ionic\nexcitations in the chain is demonstrated by inclusion of appropriately retarded\nnear-, medium and far-field components of dipole interaction between spheres in\nthe chain. It is proved that the Lorentz friction losses in each sphere are\ncompletely compensated by the energy income from the rest of the chain for a\nwide sector of the plasmon-polariton wave vector domain. There is shown that\nthe damping of plasmon-polariton is reduced to only residual Ohmic losses much\nlower than irradiation losses for the separate electrolyte sphere. The\nself-frequencies and the group velocities of plasmon-polaritons for\nlongitudinal and transversal (with respect to the chain orientation)\npolarizations are determined and assessed for various ion and electrolyte\nparameters. It is proved that there exist weakly damped self-modes of\nplasmon-polaritons in the chain for which the propagation range is limited by\nrelatively small Ohmic losses only. Completely undamped collective waves are\nalso described in the case of the presence of persistent external excitation of\nsome fragment of the chain. The possibility of application of the\nplasmon-polariton model to describe the so-called saltatory conduction in\nperiodically myelinated nerve axons is preliminarily discussed.",
        "positive": "Quantum DNA Sequencing using Gaussian Amplitude Amplification: In this study, we explore how quantum pathfinding algorithm called Gaussian\nAmplitude Amplification (GAA) can be used to solve the DNA sequencing problem.\nTo do this, sequencing by hybridization was assumed wherein short fragments of\nthe nucleic acids called oligonucleotides of length l were gathered and were\nthen assembled. The process of reassembling the sequence was then abstracted\ninto a graph problem of finding the Hamiltonian path with the least cost. The\nconstructed directed graph was then converted into sequential bipartite graphs\nin order to use GAA. The results of our simulation revealed that for the case\nwhere l = 2 and spectrum size of |S| = 4, the probability of finding the\noptimal solution (with the least cost) is approximately 70.92% - a significant\nimprovement compared to 4.17% when the path is chosen randomly. While this\nstudy only focused on the ideal scenario where there are no errors in the\nspectrum, the outcomes presented here demonstrate the plausibility of using GAA\nas a genome sequencing method."
    },
    {
        "anchor": "Topological Classification Table Implemented with Classical Passive\n  Meta-Materials: Topological condensed matter systems from class A and class AII of the\nclassification table have received classical electromagnetic and mechanical\nanalogs and protected wave-guiding with such systems has been demonstrated\nexperimentally. Here we introduce a map which generates classical analogs for\nall entries of the classification table, using only passive elements. Physical\nmechanical models are provided for all strong topological phases in dimension\n2, as well as for three classes in dimension 3. This includes topological\nsuper-conducting phases, which have never been attempted with classical\nsystems.",
        "positive": "Response of the two-dimensional electron gas of AlGaAs/GaAs\n  heterostructures to parallel magnetic field: We study the transport properties of the two-dimensional electron gas in\nAlGaAs/GaAs heterostructures in parallel to the interface magnetic fields at\nlow temperatures. The magnetoresistance in the metallic phase is found to be\npositive and weakly anisotropic with respect to the orientation of the in-plane\nmagnetic field and the current through the sample. At low electron densities\n($n_s< 5\\times 10^{10}$ cm$^{-2}$) the experimental data can be described\nadequately within spin-related approach while at high $n_s$ the\nmagnetoresistance mechanism changes as inferred from $n_s$-independence of the\nnormalized magnetoresistance."
    },
    {
        "anchor": "Many-body delocalization transition and relaxation in a quantum dot: We revisit the problem of quantum localization of many-body states in a\nquantum dot and the associated problem of relaxation of an excited state in a\nfinite correlated electron system. We determine the localization threshold for\nthe eigenstates in Fock space. We argue that the localization-delocalization\ntransition (which manifests itself, e.g., in the statistics of many-body energy\nlevels) becomes sharp in the limit of a large dimensionless conductance (or,\nequivalently, in the limit of weak interaction). We also analyze the temporal\nrelaxation of quantum states of various types (a \"hot-electron state\", a\n\"typical\" many-body state, and a single-electron excitation added to a \"thermal\nstate\") with energies below, at, and above the transition.",
        "positive": "Stabilization of collapse and revival dynamics by a non-Markovian phonon\n  bath: Semiconductor quantum dots (QDs) have been demonstrated to be versatile\ncandidates to study the fundamentals of light-matter interaction [1-3]. In\ncontrast with atom optics, dissipative processes are induced by the inherent\ncoupling to the environment and are typically perceived as a major obstacle\ntowards stable performances in experiments and applications [4].\n  In this paper we show that this is not necessarily the case. In fact, the\nmemory of the environment can enhance coherent quantum optical effects. In\nparticular, we demonstrate that the non-Markovian coupling to an incoherent\nphonon bath has a stabilizing effect on the coherent QD cavity-quantum\nelectrodynamics (cQED) by inhibiting irregular oscillations and boosting\nregular collapse and revival patterns. For low photon numbers we predict QD\ndynamics that deviate dramatically from the well-known atomic Jaynes-Cummings\nmodel. Our proposal opens the way to a systematic and deliberate design of\nphoton quantum effects via specifically engineered solid-state environments."
    },
    {
        "anchor": "Optical alignment and orientation of excitons in ensemble of core/shell\n  CdSe/CdS colloidal nanoplatelets: We report on the experimental and theoretical studies of optical alignment\nand optical orientation effects in an ensemble of core/shell CdSe/CdS colloidal\nnanoplatelets. The dependences of three Stokes parameters on the magnetic field\napplied in the Faraday geometry are measured under continuous wave resonant\nexcitation of the exciton photoluminescence. Theoretical model is developed to\ntake into account both bright and dark exciton states in the case of strong\nelectron and hole exchange interaction and random in-plane orientation of the\nnanoplatelets in ensemble. The data analysis allows us to estimate the time and\nenergy parameters of the bright and dark excitons. The optical alignment effect\nenables identification of the exciton and trion contributions to the\nphotoluminescence spectrum even in the absence of a clear spectral line\nresolution.",
        "positive": "Higgs-like pair amplitude dynamics in superconductor-quantum dot hybrids: We consider a quantum dot weakly tunnel coupled to superconducting\nreservoirs. A finite superconducting pair amplitude can be induced on the dot\nvia the proximity effect. We investigate the dynamics of the induced pair\namplitude after a quench and under periodic driving of the system by means of a\nreal-time diagrammatic approach. We find that the quench dynamics is dominated\nby an exponential decay towards equilibrium In contrast, the periodically\ndriven system can sustain coherent oscillations of both the amplitude and the\nphase of the induced pair amplitude in analogy to Higgs and Nambu-Goldstone\nmodes in driven bulk superconductors."
    },
    {
        "anchor": "Tunnel junction of helical edge states: Determining and controlling\n  spin-preserving and spin-flipping processes through transconductance: When a constriction is realized in a 2D quantum spin Hall system, electron\ntunneling between helical edge states occurs via two types of channels allowed\nby time-reversal symmetry, namely spin-preserving ({p}) and spin-flipping ({f})\ntunneling processes. Determining and controlling the effects of these two\nchannels is crucial to the application of helical edge states in spintronics.\nWe show that, despite the Hamiltonian terms describing these two processes do\nnot commute, the scattering matrix entries of the related 4-terminal setup\nalways factorize into products of p-terms and f-terms contributions. Such\nfactorization provides an operative way to determine the transmission\ncoefficient $T_p$ and $T_f$ related to each of the two processes, via\ntransconductance measurements. Furthermore, these transmission coefficients are\nalso found to be controlled independently by a suitable combination of two gate\nvoltages applied across the junction. This result holds for an arbitrary\nprofile of the tunneling amplitudes, including disorder in the tunnel region,\nenabling us to discuss the effect of the finite length of the tunnel junction,\nand the space modulation of both magnitude and phase of the tunneling\namplitudes.",
        "positive": "Theory of Spatial Optical Solitons in Metallic Nanowire Materials: We characterize the spatial optical solitons supported by arrays of metallic\nnanowires embedded in Kerr-type material. The array of nanowires is described\nusing an effective medium model and is regarded as a continuous medium. It is\nshown that the conditions necessary for the formation of spatial-solitons are\nradically different in presence of the nanowires, and in particular within the\neffective medium model spatial-solitons are allowed in the nanowire material\nonly in case the host material is a \"self-defocusing\" material. It is proven\nthat the characteristic soliton beamwidth is related to the degree of\nhyperbolicity of the isofrequency surfaces of the photonic states, and that a\nsufficiently strong electric field amplitude may enable subwavelength solitary\nwaves."
    },
    {
        "anchor": "Microwave induced nonlocal transport in two-dimensional electron system: We observe microwave induced nonlocal resistance in magnetotransport in\nsingle and bilayer electronic systems. The obtained results provide evidence\nfor an edge state current stabilized by microwave irradiation due to nonlinear\nresonances. Our observation are closely related to microwave induced\noscillations and zero resistance states in a two-dimensional (2D) electron\nsystem.",
        "positive": "Theory of polar domains in moir\u00e9 heterostructures: The discovery of unconventional ferroelectric behavior in twisted bilayers\nhas prompted the consideration of moir\\'e heterostructures as polar materials.\nHowever, misconceptions about the nature and origin of the observed\nferroelectricity indicate that a better theoretical understanding of the polar\nproperties of moir\\'e heterostructures is needed. In this paper, it is\nproposed, and verified with first-principles calculations, that all moir\\'e\nheterostructures exhibit an out-of-plane moir\\'e polar domain (MPD) structure.\nIn transition metal dichalcogenide bilayers, an interlayer charge transfer\noccurs due to the change in stacking arrangements throughout the moir\\'e\nsuperlattice, leading to a local out-of-plane dipole moment, with the magnitude\nand shape of the MPDs being dominated by the chalcogen atoms. While the MPDs in\nall heterostructures are sensitive to the moir\\'e period, it is only in the\nhomo-bilayers that they can be tuned with an out-of-plane electric field. The\nmisconceptions about ferroelectricity in moir\\'e heterostructures are\naddressed, and it is proposed that the only scenario in which the MPDs can be\nconsidered ferroelectric domains is via a global van der Waals sliding by one\nthird of a unit cell in a homo-bilayer. Finally, a general theoretical\ndiscussion of the polar properties of moir\\'e heterostructures is provided."
    },
    {
        "anchor": "Quantum coherent control of linear and nonlinear thermoelectricity on\n  graphene nanostructure heat engines: We theoretically show how structural modifications and controlling quantum\ncoherency can enhance linear and nonlinear thermoelectric performance in\ngraphene nanostructure heat engines. Although graphene has emerged as a\npromising material for a nanoscale heat engine due to its high coherency and\ntunable electronic properties, its large lattice thermal transport often limits\nits thermal efficiency. Using the density-functional tight-binding method, we\ndemonstrate that one can suppress lattice thermal transport degrading the\nthermal efficiency by deliberately manipulating the junction's bending angle at\nlow temperatures. We further argue that applying an optimal local gate voltage\nunleashes its great potential in achieving excellent efficiency and reasonably\nhigh output power that persist in the fully nonlinear regime.",
        "positive": "Nonlinear spin current generation in noncentrosymmetric spin-orbit\n  coupled systems: Spin current plays a central role in spintronics. In particular, finding more\nefficient ways to generate spin current has been an important issue and studied\nactively. For example, representative methods of spin current generation\ninclude spin polarized current injections from ferromagnetic metals, spin Hall\neffect, and spin battery. Here we theoretically propose a new mechanism of spin\ncurrent generation based on nonlinear phenomena. By using Boltzmann transport\ntheory, we show that a simple application of the electric field $\\bf{E}$\ninduces spin current proportional to $\\bf{E^2}$ in noncentrosymmetric\nspin-orbit coupled systems. We demonstrate that the nonlinear spin current of\nthe proposed mechanism is supported in the surface state of three-dimensional\ntopological insulators and two-dimensional semiconductors with the Rashba\nand/or Dresselhaus interaction. In the latter case, the angular dependence of\nthe nonlinear spin current can be manipulated by the direction of the electric\nfield and by the ratio of the Rashba and Dresselhaus interactions. We find that\nthe magnitude of the spin current largely exceeds those in the previous methods\nfor a reasonable magnitude of the electric field. Furthermore, we show that\napplication of AC electric fields (e.g. terahertz light) leads to the\nrectifying effect of the spin current where DC spin current is generated. These\nfindings will pave a new route to manipulate the spin current in\nnoncentrosymmetric crystals."
    },
    {
        "anchor": "The weak localization correction to the polarization and persistent\n  currents in mesoscopic metal rings: We re-examine the effect of electron-electron interactions on the persistent\ncurrent in mesoscopic metal rings threaded by an Aharonov-Bohm flux. The\nexchange contribution to the current is shown to be determined by the weak\nlocalization correction to the polarization. We explicitly calculate the\ncontribution from exchange interactions with momentum transfers smaller than\nthe inverse elastic mean free path to the average current, and find that it has\nthe same order of magnitude as the {\\it{canonical}} current without\ninteractions. \\\\",
        "positive": "Electron transport through a quantum dot assisted by cavity photons: We investigate transient transport of electrons through a single-quantum-dot\ncontrolled by a plunger gate. The dot is embedded in a finite wire that is\nweakly coupled to leads and strongly coupled to a single cavity photon mode. A\nnon-Markovian density-matrix formalism is employed to take into account the\nfull electron-photon interaction in the transient regime. In the absence of a\nphoton cavity, a resonant current peak can be found by tuning the plunger gate\nvoltage to lift a many-body state of the system into the source-drain bias\nwindow. In the presence of an $x$-polarized photon field, additional side peaks\ncan be found due to photon-assisted transport. By appropriately tuning the\nplunger-gate voltage, the electrons in the left lead are allowed to make\ncoherent inelastic scattering to a two-photon state above the bias window if\ninitially one photon was present in the cavity. However, this photon-assisted\nfeature is suppressed in the case of a $y$-polarized photon field due to the\nanisotropy of our system caused by its geometry."
    },
    {
        "anchor": "Hole transport across MgO-based magnetic tunnel junctions with high\n  resistance-area product due to oxygen vacancies: The quantum mechanical tunnelling process conserves the quantum properties of\nthe particle considered. As applied to solid-state tunnelling (SST), this\nphysical law was verified, within the field of spintronics, regarding the\nelectron spin in early experiments across Ge tunnel barriers, and in the 90s\nacross Al2O3 barriers. The conservation of the quantum parameter of orbital\noccupancy, as grouped into electronic symmetries, was observed in the '00s\nacross MgO barriers, followed by SrTiO3 (STO). Barrier defects, such as oxygen\nvacancies, partly conserve this electronic symmetry. In the solid-state, an\nadditional subtlety is the sign of the charge carrier: are holes or electrons\ninvolved in transport? We demonstrate that SST across MgO magnetic tunnel\njunctions (MTJs) with a large resistance-area (RA) product involves holes by\nexamining how shifting the MTJ's Fermi level alters the ensuing barrier heights\ndefined by the barrier's oxygen vacancies. In the process, we consolidate the\ndescription of tunnel barrier heights induced by specific oxygen-vacancy\ninduced localized states. Our work opens prospects to understand the concurrent\nobservation of high TMR and spin transfer torque across MgO-based nanopillars.",
        "positive": "Unconventional Yu-Shiba-Rusinov states in hydrogenated graphene: Conventional in-gap Yu-Shiba-Rusinov states require two ingredients: magnetic\natoms and a superconducting host that, in the normal phase, has a finite\ndensity of states at the Fermi energy. Here we show that hydrogenated graphene\ncan host Yu-Shiba-Rusinov states without any of those two ingredients. Atomic\nhydrogen chemisorbed in graphene is known to act as paramagnetic center with a\nweakly localized magnetic moment. Our calculations for hydrogenated graphene in\nproximity to a superconductor show that individual adatoms induce in-gap\nYu-Shiba-Rusinov states with an exotic spectrum whereas chains of adatoms\nresult in a gapless Yu- Shiba-Rusinov band. Our predictions can be tested using\nstate of the art techniques, combining recent progress of atomic manipulation\nof atomic hydrogen on graphene together with the well tested proximity effect\nin graphene."
    },
    {
        "anchor": "Phase-type distributions for studying variability in resistive memories: A new statistical approach has been developed to analyze Resistive Random\nAccess Memory (RRAM) variability. The stochastic nature of the physical\nprocesses behind the operation of resistive memories makes variability one of\nthe key issues to solve from the industrial viewpoint of these new devices. The\nstatistical features of variability have been usually studied making use of\nWeibull distribution. However, this probability distribution does not work\ncorrectly for some resistive memories, in particular for those based on the\nNi/HfO2/Si structure that has been employed in this work. A completely new\napproach based on phase-type modeling is proposed in this paper to characterize\nthe randomness of resistive memories operation. An in-depth comparison with\nexperimental results shows that the fitted phase-type distribution works better\nthan the Weibull distribution and also helps to understand the physics of the\nresistive memories.",
        "positive": "High Chern number quantum anomalous Hall phases in graphene ribbons with\n  Haldane orbital coupling: We investigate possible phase transitions among the different quantum\nanomalous Hall (QAH) phases in a zigzag graphene ribbon under the influence of\nthe exchange field. The effective tight-binding Hamiltonian for graphene is\nmade up of the hopping term, the Kane-Mele and Rashba spin-orbit couplings as\nwell as the Haldane orbital term. We find that the variation of the exchange\nfield results in bulk gap-closing phenomena and phase transitions occur in the\ngraphene system. If the Haldane orbital coupling is absent, the phase\ntransition between the chiral (anti-chiral) edge state $\\nu=+2$ ($\\nu=-2$) and\nthe pseudo-quantum spin Hall state ($\\nu=0$) takes place. Surprisingly, when\nthe Haldane orbital coupling is taken into account, an intermediate QSH phase\nwith two additional edge modes appears in between phases $\\nu=+2$ and $\\nu=-2$.\nThis intermediate phase is therefore either the hyper-chiral edge state of high\nChern number $\\nu=+4$ or anti-hyper-chiral edge state of $\\nu=-4$ when the\ndirection of exchange field is reversed. We present the band structures, edge\nstate wave functions and current distributions of the different QAH phases in\nthe system. We also report the critical exchange field values for the QAH phase\ntransitions."
    },
    {
        "anchor": "Droplet epitaxy symmetric InAs/InP quantum dots for quantum emission in\n  the third telecom window: morphology, optical and electronic properties: The rapidly developing quantum communication technology requires\ndeterministic quantum emitters that can generate single photons and entangled\nphoton pairs in the third telecom window, in order to be compatible with\nexisting optical fiber networks and on-chip silicon photonic processors.\nInAs/InP quantum dots (QDs) are among the leading candidates for this purpose,\ndue to their high emission efficiency in the required spectral range. However,\nfabricating versatile InAs/InP QD-based quantum emitters is challenging,\nespecially as these QDs typically have asymmetric profiles in the growth plane,\nresulting in a substantial bright-exciton fine structure splitting (FSS). This\nhinders the generation of entangled photon pairs and thus, compromises the\nversatility of InAs/InP QDs. We overcome this by implementing droplet epitaxy\n(DE) synthesis of low surface density (2.8$\\times$10$^8$ cm$^{-2}$) InAs QDs on\nan (001)-oriented InP substrate. The resulting QDs are located in etched pits,\nhave concave bases, and most importantly, have symmetric in-plane profiles. We\nprovide an analytical model to explain the kinetics of pit formation and QD\nbase shape modification. Our theoretical calculations of electronic states\nreveal the properties of neutral and charged excitons and biexcitons confined\nin such QDs, which agree with the optical investigations of individual QDs. The\noptical response of QD ensembles suggests that FSS may indeed be negligible, as\nreflected in the vanishing degree of linear polarization. However, single QD\nspectrum gathered from an etched mesa shows moderate FSS of (50$\\pm$5) $\\mu$eV\nthat we link to destructive changes made in the QD environment during the\npost-growth processing. Finally, we show that the studied DE QDs provide a\nclose-to-ideal single-photon emission purity of (92.5$\\pm$7.5) $\\%$ in the\nthird telecom window.",
        "positive": "Shift of Dirac points and strain induced pseudo-magnetic field in\n  graphene: We propose that the strain induced effective pseudo-magnetic field in\ngraphene can also be explained by a curl movement of the Dirac points, if the\nDirac points can be regarded as a slowly varying function of position. We also\nprove that the Dirac points must be confined within two triangles, each one has\n1/8 the area of the Brillouin zone."
    },
    {
        "anchor": "Characterizing and Tuning Exceptional Points Using Newton Polygons: The study of non-Hermitian degeneracies -- called exceptional points -- has\nbecome an exciting frontier at the crossroads of optics, photonics, acoustics,\nand quantum physics. Here, we introduce the Newton polygon method as a general\nalgebraic framework for characterizing and tuning exceptional points. These\npolygons were first described by Isaac Newton in 1676 and are conventionally\nused in algebraic geometry, with deep roots in various topics in modern\nmathematics. We have found their surprising connection to non-Hermitian\nphysics. We propose and illustrate how the Newton polygon method can enable the\nprediction of higher-order exceptional points, using a recently experimentally\nrealized optical system. Using the paradigmatic Hatano-Nelson model, we\ndemonstrate how our Newton Polygon method can be used to predict the presence\nof the non-Hermitian skin effect. As further application of our framework, we\nshow the presence of tunable exceptional points of various orders in\n$PT$-symmetric one-dimensional models. We further extend our method to study\nexceptional points in higher number of variables and demonstrate that it can\nreveal rich anisotropic behaviour around such degeneracies. Our work provides\nan analytic recipe to understand and tune exceptional physics.",
        "positive": "Half-mirror for electrons on quantum Hall copropagating edge channels: A half-mirror that divides a spin-polarized electron into two parallel\ncopropagating spin-resolved quantum Hall edge channels one half each is\npresented in this study. The partition process was coherent, as confirmed by\nobserving the Aharonov-Bohm oscillation at a high visibility of up to 60% in a\nMach-Zehnder interferometer, which comprised two such half-mirrors. The device\ncharacteristics were highly stable, making the device promising in the\napplication of quantum information processing. The beam-splitting process is\ntheoretically modelled, and the numerical simulation successfully reproduces\nthe experimental observation. The partition of the electron accompanied by the\nspin rotation is explained by the angular momentum transfer from the orbital to\nthe spin via spin-orbit interactions."
    },
    {
        "anchor": "Robust midgap states in band-inverted junctions under electric and\n  magnetic fields: Several IV-VI semiconductor compounds made of heavy atoms, such as\nPb$_{1-x}$Sn$_{x}$Te, may undergo band-inversion at the $L$ point of the\nBrillouin zone upon variation of their chemical composition. This inversion\ngives rise to topologically distinct phases, characterized by a change in a\ntopological invariant. In the framework of the $\\mathbf{k}\\cdot\\mathbf{p}$\ntheory, band-inversion can be viewed as a change of sign of the fundamental\ngap. A two-band model within the envelope-function approximation predicts the\nappearance of midgap interface states with Dirac cone dispersions in\nband-inverted junctions, namely, when the gap changes sign along the growth\ndirection. We present a thorough study of these interface electron states in\nthe presence of crossed electric and magnetic fields, the electric field being\napplied along the growth direction of a band-inverted junction. We show that\nthe Dirac cone is robust and persists even if the fields are strong. In\naddition, we point out that Landau levels of electron states lying in the\nsemiconductor bands can be tailored by the electric field. Tunable devices are\nthus likely to be realizable exploiting the properties studied herein.",
        "positive": "Spin-filtered edge states in graphene: Spin orbit coupling changes graphene, in principle, into a two-dimensional\ntopological insulator, also known as quantum spin Hall insulator. One of the\nexpected consequences is the existence of spin-filtered edge states that carry\ndissipationless spin currents and undergo no back-scattering in the presence of\nnon-magnetic disorder, leading to quantization of conductance. Whereas, due to\nthe small size of spin orbit coupling in graphene, the experimental observation\nof these remarkable predictions is unlikely, the theoretical understanding of\nthese spin-filtered states is shedding light on the electronic properties of\nedge states in other two-dimensional quantum spin Hall insulators. Here we\nreview the effect of a variety of perturbations, like curvature, disorder, edge\nreconstruction, edge crystallographic orientation, and Coulomb interactions on\nthe electronic properties of these spin filtered states."
    },
    {
        "anchor": "Merging of Dirac points in a two-dimensional crystal: We study under which general conditions a pair of Dirac points in the\nelectronic spectrum of a two-dimensional crystal may merge into a single one.\nThe merging signals a topological transition between a semi-metallic phase and\na band insulator. We derive a universal Hamiltonian that describes the physical\nproperties of the transition, which is controlled by a single parameter, and\nanalyze the Landau-level spectrum in its vicinity. This merging may be observed\nin the organic salt alpha-(BEDT-TTF)_2 I_3 or in an optical lattice of cold\natoms simulating deformed graphene.",
        "positive": "Role of quantum entanglement due to a magnetic impurity on current\n  magnification effect in mesoscopic open rings: We study the current magnification effect in presence of exchange scattering\nof electron from a magnetic impurity placed in one arm of an open mesoscopic\nring. The exchange interaction causes entanglement of electron spin and\nimpurity spin. Earlier studies have shown that such an entanglement causes\nreduction or loss of interference in the Aharonov-Bohm oscillations leading to\ndecoherence. We find however, that this entanglement, in contradiction to the\nnaive expectation of a reduction of current magnification, leads to enhancement\nas well as suppression of the effect. We also observe additional novel features\nlike new resonances and current reversals."
    },
    {
        "anchor": "Plasmonic modes in cylindrical nanoparticles and dimers: We present analytical expressions for the resonance frequencies of the\nplasmonic modes hosted in a cylindrical nanoparticle within the quasistatic\napproximation. Our theoretical model gives us access to both the longitudinally\nand transversally polarized dipolar modes for a metallic cylinder with an\narbitrary aspect ratio, which allows us to capture the physics of both\nplasmonic nanodisks and nanowires. We also calculate quantum mechanical\ncorrections to these resonance frequencies due to the spill-out effect, which\nis of relevance for cylinders with nanometric dimensions. We go on to consider\nthe coupling of localized surface plasmons in a dimer of cylindrical\nnanoparticles, which leads to collective plasmonic excitations. We extend our\ntheoretical formalism to construct an analytical model of the dimer, describing\nthe evolution with the inter-nanoparticle separation of the resultant bright\nand dark collective modes. We comment on the renormalization of the coupled\nmode frequencies due to the spill-out effect, and discuss some methods of\nexperimental detection.",
        "positive": "Plasmon-magnon interactions in two-dimensional honeycomb magnets: Two-dimensional honeycomb ferromagnets offer the unprecedented opportunity to\nstudy interactions between collective modes that in standard bulk ferromagnets\ndo not cross paths. Indeed, they harbor an optical spin-wave branch, i.e. a\nspin wave which disperses weakly near the Brillouin zone center. When doped\nwith free carriers, they also host the typical gapless plasmonic mode of 2D\nitinerant electron/hole systems. When the plasmon branch meets the optical\nspin-wave branch, energy and momentum matching occurs, paving the way for\ninteractions between the charge and spin sector. In this Letter we present a\nmicroscopic theory of such plasmon-magnon interactions, which is based on a\ndouble random phase approximation. We comment on the possibility to unveil this\nphysics in recently isolated 2D honeycomb magnets such as ${\\rm Cr}_2{\\rm\nGe}_2{\\rm Te}_6$."
    },
    {
        "anchor": "Coherent coupling of two remote magnonic resonators mediated by\n  superconducting circuits: We demonstrate microwave-mediated distant magnon-magnon coupling on a\nsuperconducting circuit platform, incorporating chip-mounted single-crystal\nY$_3$Fe$_5$O$_{12}$ (YIG) spheres. Coherent level repulsion and dissipative\nlevel attraction between the magnon modes of the two YIG spheres are\ndemonstrated. The former is mediated by cavity photons of a superconducting\nresonator, and the latter is mediated by propagating photons of a coplanar\nwaveguide. Our results open new avenues towards exploring integrated hybrid\nmagnonic networks for coherent information processing on a quantum-compatible\nsuperconducting platform.",
        "positive": "The Effects of Resonant Tunneling on Magnetoresistance through a Q\n  uantum Dot: The effect of resonant tunneling on magnetoresistance (MR) is studied\ntheoretically in a double junction system. We have found that the ratio of the\nMR of the resonant peak current is reduced more than that of the single\njunction, whereas that of the valley current is enhanced depending on the\nchange of the discrete energy-level under the change of magnetic field. We also\nfound that the peak current-valley current (PV) ratio decreases when the\njunction conductance increases."
    },
    {
        "anchor": "Full-band electronic structure calculation of semiconductor\n  nanostructures: a reduced-order approach: We propose an efficient reduced-order technique for electronic structure\ncalculations of semiconductor nanostructures, suited for inclusion in full-band\nquantum transport simulators. The model is based on the linear combination of\nbulk bands obtained by the empirical pseudopotential method, combined with the\nuse of problem-matched basis functions numerically generated from the singular\nvalue decomposition. The efficiency and accuracy of the proposed approach are\ndemonstrated in the case of the dispersion relation of hole subbands in an\nunstrained GaN layer.",
        "positive": "Transport in single-molecule transistors: Kondo physics and negative\n  differential resistance: We report two examples of transport phenomena based on sharp features in the\neffective density of states of molecular-scale transistors: Kondo physics in\nC$_{60}$-based devices, and gate-modulated negative differential resistance\n(NDR) in ``control'' devices that we ascribe to adsorbed contamination. We\ndiscuss the need for a statistical approach to device characterization, and the\ncriteria that must be satisfied to infer that transport is based on single\nmolecules. We describe apparent Kondo physics in C$_{60}$-based single-molecule\ntransistors (SMTs), including signatures of molecular vibrations in the Kondo\nregime. Finally, we report gate-modulated NDR in devices made without\nintentional molecular components, and discuss possible origins of this\nproperty."
    },
    {
        "anchor": "Adiabatic pumping through an interacting quantum dot with spin-orbit\n  coupling: We study adiabatic pumping through a two-level quantum dot with spin-orbit\ncoupling. Using a diagrammatic real-time approach, we calculate both the pumped\ncharge and spin for a periodic variation of the dot's energy levels in the\nlimit of weak tunnel coupling. Thereby, we compare the two limits of vanishing\nand infinitely large charging energy on the quantum dot. We discuss the\ndependence of the pumped charge and pumped spin on gate voltages, the symmetry\nin the tunnel-matrix elements and spin-orbit coupling strength. We identify the\npossibility to generate pure spin currents in the absence of charge currents.",
        "positive": "Transport through a quantum dot coupled to two Majorana bound states: We investigate electron transport inside a ring system composed of a quantum\ndot (QD) coupled to two Majorana bound states confined at the ends of a\none-dimensional topological superconductor nanowire. By tuning the magnetic\nflux threading through the ring, the model system we consider can be switched\ninto states with or without zero-energy modes when the nanowire is in its\ntopological phase. We find that the Fano profile in the conductance spectrum\ndue to the interference between bound and continuum states exhibits markedly\ndifferent features for these two different situations, which consequently can\nbe used to detect the Majorana zero-energy mode. Most interestingly, as a\nperiodic function of magnetic flux, the conductance shows $2\\pi$ periodicity\nwhen the two Majorana bound states are nonoverlapping (as in an infinitely long\nnanowire) but displays $4\\pi$ periodicity when the overlapping becomes nonzero\n(as in a finite length nanowire). We map the model system into a QD--Kitaev\nring in the Majorana fermion representation and affirm these different\ncharacteristics by checking the energy spectrum."
    },
    {
        "anchor": "High-impedance surface acoustic wave resonators: Because of their small size, low loss, and compatibility with magnetic fields\nand elevated temperatures, surface acoustic wave resonators hold significant\npotential as future quantum interconnects. Here, we design, fabricate, and\ncharacterize GHz-frequency surface acoustic wave resonators with the potential\nfor strong capacitive coupling to nanoscale solid-state quantum systems,\nincluding semiconductor quantum dots. Strong capacitive coupling to such\nsystems requires a large characteristic impedance, and the resonators we\nfabricate have impedance values above 100 $\\Omega$. We achieve such high\nimpedance values by tightly confining a Gaussian acoustic mode. At the same\ntime, the resonators also have low loss, with quality factors of several\nthousand at millikelvin temperatures. These high-impedance resonators are\nexpected to exhibit large vacuum electric-field fluctuations and have the\npotential for strong coupling to a variety of solid-state quantum systems.",
        "positive": "From Fowler-Nordheim to Non-Equilibrium Green's Function Modeling of\n  Tunneling: In this work, an analytic model is proposed which provides in a continuous\nmanner the current-voltage characteristic (I-V) of high performance tunneling\nfield-effect transistors (TFETs) based on direct bandgap semiconductors. The\nmodel provides closed-form expressions for I-V based on: 1) a modified version\nof the well-known Fowler-Nordheim (FN) formula (in the ON-state), and 2) an\nequation which describes the OFF-state performance while providing continuity\nat the ON/OFF threshold by means of a term introduced as the \"continuity\nfactor\". It is shown that traditional approaches such as FN are accurate in\nTFETs only through correct evaluation of the total band bending distance and\nthe \"tunneling effective mass\". General expressions for these two key\nparameters are provided. Moreover, it is demonstrated that the tunneling\neffective mass captures both the ellipticity of evanescent states and the dual\n(electron/hole) behavior of the tunneling carriers, and it is further shown\nthat such a concept is even applicable to semiconductors with nontrivial energy\ndispersion. Ultimately, it is found that the I-V characteristics obtained by\nusing this model are in close agreement with state-of-the-art quantum transport\nsimulations both in the ON- and OFF-state, thus providing validation of the\nanalytic approach."
    },
    {
        "anchor": "Directional Locking and the Influence of Obstacle Density on Skyrmion\n  Dynamics in Triangular and Honeycomb Arrays: We numerically examine a single skyrmion dynamics under the influence of\ntriangular and honeycomb obstacle arrays at zero temperature. The skyrmion Hall\nangle $\\theta_{sk}$, that is the angle between the applied external drive and\nthe direction of the skyrmion motion, increases in quantized steps or\ncontinuously as a function of the applied drive. For the obstacle arrays\nstudied in this work, the skyrmion exhibits two main directional locking\neffects, where the skyrmion motion locks with $\\theta_{sk}=-30^\\circ$ and\n$-60^\\circ$. We show that these directions are privileged due to the obstacle\nlandscape symmetry, where there are channels that the skyrmion may move with\nless or no obstacle collisions. Besides that, the skyrmion Hall angles can be\nmodified by changing the obstacle density in the sample, where some dynamic\nphases may appear, vanish or be stimulated. This interesting behavior can be\nuseful to guide skyrmions using regions with different obstacle densities to\nset the skyrmion into designed trajectories. We have also investigated for\nfixed obstacle densities how the phases with $\\theta_{sk}=-30^\\circ$ and\n$-60^\\circ$ evolve as a function of the Magnus force, where possibilities for\nswitching between these phases and topological selection is discussed.",
        "positive": "Dynamics of coherences in the interacting double-dot Aharonov-Bohm\n  interferometer: Exact numerical simulations: We study the real time dynamics of electron coherence in a double quantum dot\ntwo-terminal Aharonov-Bohm geometry, taking into account repulsion effects\nbetween the dots' electrons. The system is simulated by extending a numerically\nexact path integral method, suitable for treating transport and dissipation in\nbiased impurity models [Phys. Rev. B 82, 205323 (2010)]. Numerical simulations\nat finite interaction strength are supported by master equation calculations in\ntwo other limits: assuming non-interacting electrons, and working in the\nCoulomb blockade regime. Focusing on the intrinsic coherence dynamics between\nthe double-dot states, we find that its temporal characteristics are preserved\nunder weak-to-intermediate inter-dot Coulomb interaction. In contrast, in the\nCoulomb blockade limit, a master equation calculation predicts coherence\ndynamics and a steady-state value which notably deviate from the finite\ninteraction case."
    },
    {
        "anchor": "Light-driven Lifshitz transitions in non-Hermitian multi-Weyl semimetals: Non-Hermitian topological systems are the newest additions to the growing\nfield of topological matter. In this work, we report of the light-driven\nexceptional physics in a multi-Weyl semi-metal. The driving is not only a key\ningredient to control the position of the exceptional contours (ECs), light\nalso has the ability to generate new ECs. Interestingly, we also demonstrate\ntopological charge distribution and Lifshitz transition, which are controllable\nby the driving field in such generated ECs. Our findings present a promising\nplatform for the manipulation and control over exceptional physics in\nnon-Hermitian topological matter.",
        "positive": "The sign of electron g-factor in GaAs(1-x)N(x) measured by using the\n  Hanle effect: Positive signs of the effective g-factors for free electrons in the\nconduction band and electrons localized on deep paramagnetic centers have been\nmeasured in nitrogen dilute alloy GaAs{0.979}N{0.021} at room temperature. The\ng-factor signs have been determined from an asymmetry in the depolarization of\nedge photoluminescence in a transverse magnetic field (Hanle effect) at the\noblique incidence of the exciting radiation and oblique-angle detection of the\nluminescence. The tilted spin polarization of free electrons is induced under\ninterband absorption of circularly polarized light, and the paramagnetic\ncenters acquire spin polarization because of spin-dependent capture of free\nspin-polarized electrons by these centers. The measured Hanle curve is a\nsuperposition of two lines, narrow and broad, with the widths ~400 G and ~50000\nG, arising due to the depolarization of localized and free electrons,\nrespectively. The magnitude and direction of the asymmetry in the measured\nHanle curve have been found to depend on the partial contributions to the\nphotoluminecsence from the heavy- and light-hole subbands split by a uniaxial\ndeformation of the GaAs{1-x}N{x} film grown on a GaAs substrate. We have\nextended the theory of optical orientation in order to calculate the excitation\nspectrum of the photoelectron tilted-spin polarization and the\ncircularly-polarized luminescence spectrum taking into account that, in the\nstrained samples under study, the light-hole subband lies above the heavy-hole\none. The results have further been used to calculate the shape of Hanle curve\nas a function of the excitation and registration energies as well as the\nincidence and detection angles and to compare the theory with experiment."
    },
    {
        "anchor": "Linking Spatial Distributions of Potential and Current in Viscous\n  Electronics: Viscous electronics is an emerging field dealing with systems in which\nstrongly interacting electrons behave as a fluid. Electron viscous flows are\ngoverned by a nonlocal current-field relation which renders the spatial\npatterns of current and electric field strikingly distinct. Notably, driven by\nthe viscous friction force from adjacent layers, current can flow against the\nelectric field, generating negative resistance, vorticity and vortices.\nMoreover, different current flows can result in identical potential\ndistributions. This sets a new situation where inferring the electron flow\npattern from the measured potentials presents a nontrivial problem. Using the\ninherent relation between these patterns through the complex analysis, here we\npropose a method for extracting the current flows from potential distributions\nmeasured in the presence of a magnetic field.",
        "positive": "Kinetics of the Phase Separation Transition in Cold-Atom Boson-Fermion\n  Mixtures: We study the kinetics of the first order phase separation transition in\nboson-fermion cold-atom mixtures. At sufficiently low temperatures such a\ntransition is driven by quantum fluctuations responsible for the formation of\ncritical nuclei of a stable phase. Based on a microscopic description of\ninteracting boson-fermion mixtures we derive an effective action for the\ncritical droplet and obtain an asymptotic expression for the nucleation rate in\nthe vicinity of the phase transition and near the spinodal instability of the\nmixed phase. We also discuss effects of dissipation which play a dominant role\nclose to the transition point, and identify the regimes where quantum\nnucleation can be experimentally observed in cold-atom systems."
    },
    {
        "anchor": "Theory of stripe domains in magnetic shape memory alloys: The evolution of multivariant patterns in thin plates of magnetic shape\nmemory materials with an applied magnetic field was studied theoretically. A\ngeometrical domain-model is considered composed of straight stripe-like\nmartensite variants with constant internal magnetization (high anisotropy\nlimit) and magnetic domain wall orientation fixed by the twin boundaries.\nThrough integral transforms of the demagnetization energy, the micromagnetic\nenergy is cast into a form convenient for direct numerical evaluation and\nanalytical calculations. The equilibrium geometrical parameters of multivariant\npatterns with straight and oblique twin boundaries have been derived as\nfunctions of the applied field and the material parameters of a plate. It is\nshown that the oblique multivariant states exist only in plates with\nthicknesses L larger than a certain critical value L_0. In samples with L < L_0\na magnetic-field-driven transformation occurs directly between single variant\nstates.",
        "positive": "Effects of heterostrain and lattice relaxation on optical conductivity\n  of twisted bilayer graphene: We present a theoretical study of the effects of heterostrain and lattice\nrelaxation on the optical conductivity of twisted bilayer graphene near the\nmagic angle, based on the band structures obtained from a continuum model. We\nfind that heterostrain, lattice relaxation and their combination give rise to\nvery distinctive spectroscopic features in the optical conductivity, which can\nbe used to probe and distinguish these effects. From the spectrum at various\nFermi energies, important features in the strain- and relaxation-modified band\nstructure such as the bandgap, bandwidth and van Hove singularities can be\ndirectly measured. The peak associated with the transition between the flat\nbands in the optical conductivity are highly sensitive to the direction of the\nstrain, which can provide direct information on the strain-modified flat bands."
    },
    {
        "anchor": "Power dependence of electric dipole spin resonance: We develop a formalism of electric dipole spin resonance (EDSR) based on\nslanting magnetic field, where we especially investigate the microwave\namplitude dependence. With increasing microwave amplitude, the Rabi frequency\nincreases linearly for a spin confined in a harmonic potential. How- ever, when\nthe spin is confined in the double-well potential, the Rabi frequency shows\nsub-linear dependence with increasing the microwave amplitude.",
        "positive": "Orbital Hanle Magnetoresistance in a 3d Transition Metal: The Hanle magnetoresistance is a telltale signature of spin precession in\nnonmagnetic conductors, in which strong spin-orbit coupling generates edge spin\naccumulation via the spin Hall effect. Here, we report the existence of a large\nHanle magnetoresistance in single layers of Mn with weak spin-orbit coupling,\nwhich we attribute to the orbital Hall effect. The simultaneous observation of\na sizable Hanle magnetoresistance and vanishing small spin Hall\nmagnetoresistance in BiYIG/Mn bilayers corroborates the orbital origin of both\neffects. We estimate an orbital Hall angle of 0.016, an orbital relaxation time\nof 2 ps and diffusion length of the order of 2 nm in disordered Mn. Our\nfindings indicate that current-induced orbital moments are responsible for\nmagnetoresistance effects comparable to or even larger than those determined by\nspin moments, and provide a tool to investigate nonequilibrium orbital\ntransport phenomena."
    },
    {
        "anchor": "Laser induced modulation of the Landau level structure in single-layer\n  graphene: We present perturbative analytical results of the Landau level quasienergy\nspectrum, autocorrelation function and out of plane pseudospin polarization for\na single graphene sheet subject to intense circularly polarized terahertz\nradiation. For the quasienergy spectrum, we find a striking non trivial\nlevel-dependent dynamically induced gap structure. This photoinduced modulation\nof the energy band structure gives rise to shifts of the revival times in the\nautocorrelation function and it also leads to modulation of the oscillations in\nthe dynamical evolution of the out of plane pseudospin polarization, which\nmeasures the angular momentum transfer between light and graphene electrons.\nFor a coherent state, chosen as an initial pseudospin configuration, the\ndynamics induces additional quantum revivals of the wave function that manifest\nas shifts of the maxima and minima of the autocorrelation function, with\nadditional partial revivals and beating patterns. These additional maxima and\nbeating patterns stem from the effective dynamical coupling of the static\neigenstates. We discuss the possible experimental detection schemes of our\ntheoretical results and their relevance in new practical implementation of\nradiation fields in graphene physics.",
        "positive": "Dynamic Nuclear Polarization by optical Stark effect in\n  periodically-pumped gallium arsenide: Optical pump-probe time- and magnetic-field-resolved Kerr rotation\nmeasurements provide a window into the mechanisms that generate dynamic nuclear\npolarization in bulk gallium arsenide. Previously, we have reported an\nunexpected dependence of the direction of the nuclear polarization on the sweep\ndirection of the applied external magnetic field. In this paper, we present\nnumerical calculations based on a model for this nuclear polarization due to\nthe optical orientation and optical Stark effect produced by a train of\nultrafast optical pulses. We demonstrate the correspondence of the model to our\nexperimental measurements for different laser wavelengths and magnetic field\nsweep rates. Finally, we show that the model reproduces the sweep direction\ndependence and provides an explanation for this behavior."
    },
    {
        "anchor": "Three-electron anisotropic quantum dots in variable magnetic fields:\n  exact results for excitation spectra, spin structures, and entanglement: Exact-diagonalization calculations for N=3 electrons in anisotropic quantum\ndots, covering a broad range of confinement anisotropies and strength of\ninter-electron repulsion, are presented for zero and low magnetic fields. The\nexcitation spectra are analyzed as a function of the strength of the magnetic\nfield and for increasing quantum-dot anisotropy. Analysis of the intrinsic\nstructure of the many-body wave functions through spin-resolved two-point\ncorrelations reveals that the electrons tend to localize forming Wigner\nmolecules. For certain ranges of dot parameters (mainly at strong anisotropy),\nthe Wigner molecules acquire a linear geometry, and the associated wave\nfunctions with a spin projection S_z=1/2 are similar to the representative\nclass of strongly entangled states referred to as W-states. For other ranges of\nparameters (mainly at intermediate anisotropy), the Wigner molecules exhibit a\nmore complex structure consisting of two mirror isosceles triangles. This\nlatter structure can be viewed as an embryonic unit of a zig-zag Wigner crystal\nin quantum wires. The degree of entanglement in three-electron quantum dots can\nbe quantified through the use of the von Neumann entropy.",
        "positive": "Electron-electron scattering and magnetoresistance of ballistic\n  microcontacts: Using a semiclassical Boltzmann equation, we calculate corrections to the\nSharvin conductance of a wide 2DEG ballistic contact that result from an\nelectron--electron scattering in the leads. These corrections are dominated by\ncollisions of electrons with nearly opposite momenta that come from different\nreservoirs. They are positive, increase with temperature, and are strongly\nsuppressed by a magnetic field. We argue that this suppression may be\nresponsible for an anomalous positive magnetoresistance observed in a recent\nexperiment."
    },
    {
        "anchor": "Spin-dependent gain and loss in photonic quantum spin Hall systems: Topological phases are greatly enriched by including non-Hermiticity. While\nmost works focus on the topology of the eigenvalues and eigenstates, how\ntopologically nontrivial non-Hermitian systems behave in dynamics has only\ndrawn limited attention. Here, we consider a breathing honeycomb lattice known\nto emulate the quantum spin Hall effect and exhibits higher-order corner modes.\nWe find that non-reciprocal intracell couplings introduce gain in one\npseudo-spin subspace while loss with the same magnitude in the other. In\naddition, non-reciprocal intracell couplings can also suppress the spin mixture\nof the edge modes at the boundaries and delocalize the higher-order corner\nmode. Our findings deepen the understanding of non-Hermitian topological phases\nand bring in the spin degree of freedom in manipulating the dynamics in\nnon-Hermitian systems.",
        "positive": "Strong mechanical driving of a single electron spin: Quantum devices for sensing and computing applications require coherent\nquantum systems which can be manipulated in a fast and robust way. Such quantum\ncontrol is typically achieved using external electric or magnetic fields which\ndrive the system's orbital or spin degrees of freedom. However, most of these\napproaches require complex and unwieldy antenna or gate structures, and with\nfew exceptions are limited to the regime of weak driving. Here, we present a\nnovel approach to strongly and coherently drive a single electron spin in the\nsolid state using internal strain fields in an integrated quantum device.\nSpecifically, we study individual Nitrogen-Vacancy (NV) spins embedded in\ndiamond mechanical oscillators and exploit the intrinsic strain coupling\nbetween spin and oscillator to strongly drive the spins. As hallmarks of the\nstrong driving regime, we directly observe the energy spectrum of the emerging\nphonon-dressed states and employ our strong, continuous driving for enhancement\nof the NV spin coherence time. Our results constitute a first step towards\nstrain-driven, integrated quantum devices and open new perspectives to\ninvestigate unexplored regimes of strongly driven multi-level systems and to\nstudy exotic spin dynamics in hybrid spin-oscillator devices."
    },
    {
        "anchor": "Phonon-assisted inter-valley scattering determines ultrafast exciton\n  dynamics in MoSe$_2$ bilayers: While valleys (energy extrema) are present in all band structures of solids,\ntheir preeminent role in determining exciton resonances and dynamics in\natomically thin transition metal dichalcogenides (TMDC) is unique. Using\ntwo-dimensional coherent electronic spectroscopy, we find that exciton\ndecoherence occurs on a much faster time scale in MoSe$_2$ bilayers than that\nin the monolayers. We further identify two population relaxation channels in\nthe bilayer, a coherent and an incoherent one. Our microscopic model reveals\nthat phonon-emission processes facilitate scattering events from the $K$ valley\nto other lower energy $\\Gamma$ and $\\Lambda$ valleys in the bilayer. Our\ncombined experimental and theoretical studies unequivocally establish different\nmicroscopic mechanisms that determine exciton quantum dynamics in TMDC\nmonolayers and bilayers. Understanding exciton quantum dynamics provides\ncritical guidance to manipulation of spin/valley degrees of freedom in TMDC\nbilayers.",
        "positive": "Topological Phase Transitions of Interacting Fermions in the Presence of\n  a Commensurate Magnetic Flux: Motivated by recently reported magnetic-field induced topological phases in\nultracold atoms and correlated Moir\\'e materials, we investigate topological\nphase transitions in a minimal model consisting of interacting spinless\nfermions described by the Hofstadter model on a square lattice. For interacting\nlattice Hamiltonians in the presence of a commensurate magnetic flux it has\nbeen demonstrated that the quantized Hall conductivity is constrained by a\nLieb-Schultz-Mattis (LSM)-type theorem due to magnetic translation symmetry. In\nthis work, we revisit the validity of the theorem for such models and establish\nthat a topological phase transition from a topological to a trivial insulating\nphase can be realized but must be accompanied by spontaneous magnetic\ntranslation symmetry breaking caused by charge ordering of the spinless\nfermions. To support our findings, the topological phase diagram for varying\ninteraction strength is mapped out numerically with exact diagonalization for\ndifferent flux quantum ratios and band fillings using symmetry indicators. We\ndiscuss our results in the context of the LSM-type theorem."
    },
    {
        "anchor": "Electrostatic effects on contacts to carbon nanotube transistors: We use numerical simulations to investigate the effect of electrostatics on\nthe source and drain contacts of carbon nanotube field-effect transistors. We\nfind that unscreened charge on the nanotube at the contact-channel interface\nleads to a potential barrier that can significantly hamper transport through\nthe device. This effect is largest for intermediate gate voltages and for\ncontacts near the ohmic-Schottky crossover, but can be mitigated with a\nreduction in the gate oxide thickness. These results help to elucidate the\nimportant role that contact geometry plays in the performance of carbon\nnanotube electronic devices.",
        "positive": "Optomagnonics in dispersive media: magnon-photon coupling enhancement at\n  the epsilon-near-zero frequency: Reaching strong light-matter coupling in solid-state systems has been long\npursued for the implementation of scalable quantum devices. Here, we put\nforward the concept of a platform capable of achieving strong coupling between\nmagnetic excitations (magnons) and optics based in an epsilon-near-zero medium,\nthat's it, a medium in which the permittivity is close to zero. We adopt a\nphenomenological approach to quantize the electromagnetic field inside a\ndispersive magnetic medium and obtain a Hamiltonian describing the interaction\nbetween photons and magnons and the frequency-dependent coupling. We predict\nthat, in the epsilon-near-zero regime, the single-magnon photon optomagnonic\ncoupling can be comparable to the uniform magnon's frequency for small magnetic\nvolumes. For state-of-the-art illustrative values, this would correspond to\nachieving the single-magnon strong coupling regime, where the coupling rate is\nlarger than all the decay rates. Finally, we show that the non-linear energy\nspectrum intrinsic to this coupling regime regime can be probed via the\ncharacteristic multiple magnon sidebands in the photon power spectrum."
    },
    {
        "anchor": "Proposed Graphene Nanospaser: We show that graphene monolayer coupled to multi-quantum well system can form\na graphene spaser, which is a coherent quantum generator of surface plasmons in\ngraphene. The active element of graphene spaser is a multi-quantum well system\nwith a design similar to the design of an active element of quantum cascade\nlaser. Under realistic parameters of the multi-quantum well system, the spasing\nin graphene monolayer can be achieved at a finite doping of graphene and at a\nplasmon frequency, 0.15 eV, close to the typical frequency of intersubband\ntransitions in multi-quantum well systems.",
        "positive": "Relativistic magnetotransport in graphene: We study the thermal and electric transport of a fluid of interacting Dirac\nfermions as they arise in single-layer graphene. We include Coulomb\ninteractions, a dilute density of charged impurities and the presence of a\nmagnetic field to describe both the static and the low frequency response as a\nfunction of temperature T and chemical potential mu. In the critical regime mu\n<< T where both bands above and below the Dirac point contribute to transport\nwe find pronounced deviations from Fermi liquid behavior, universal,\ncollision-dominated values for transport coefficients and a cyclotron resonance\nof collective nature. In the collision-dominated high temperature regime the\nlinear thermoelectric transport coefficients are shown to obey the constraints\nof relativistic magnetohydrodynamics which we derive microscopically from\nBoltzmann theory. The latter also allows us to describe the crossover to\ndisorder-dominated Fermi liquid behavior at large doping and low temperatures,\nas well as the crossover to the ballistic regime at high fields."
    },
    {
        "anchor": "Hydrodynamic approach to electronic transport in graphene: energy\n  relaxation: In nearly compensated graphene, disorder-assisted electron-phonon scattering\nor \"supercollisions\" are responsible for both quasiparticle recombination and\nenergy relaxation. Within the hydrodynamic approach, these processes contribute\nweak decay terms to the continuity equations at local equilibrium, i.e., at the\nlevel of \"ideal\" hydrodynamics. Here we report the derivation of the decay term\ndue to weak violation of energy conservation. Such terms have to be considered\non equal footing with the well-known recombination terms due to nonconservation\nof the number of particles in each band. At high enough temperatures in the\n\"hydrodynamic regime\" supercollisions dominate both types of the interaction).\nWe also discuss the contribution of supercollisions to the heat transfer\nequation (generalizing the continuity equation for the energy density in\nviscous hydrodynamics).",
        "positive": "Bottom-gated epitaxial graphene suitable for half-integer quantum\n  metrology ?: We demonstrate that the carrier concentration of epitaxial graphene devices\ngrown on the C-face of a SiC substrate is efficiently modulated by a buried\ngate. The gate is fabricated via the implantation of nitrogen atoms in the SiC\ncrystal, 200 nm below the surface, and works well at intermediate temperatures:\n40K-80K. The Dirac point is observed at moderate gate voltages (1-20V)\ndepending upon the surface preparation. For temperatures below 40K, the gate is\ninefficient as the buried channel is frozen out. However, the carrier\nconcentration in graphene remains very close to the value set at T\\sim 40K. The\nabsence of parallel conduction is evidenced by the observation of the\nhalf-integer quantum Hall effect at various concentrations at T\\sim 4K. These\nobservations pave the way to a better understanding of intrinsic properties of\nepitaxial graphene and are promising for applications such as quantum\nmetrology."
    },
    {
        "anchor": "Quantitative measurements of the thermopower of Andreev interferometers: Using a new second derivative technique and thermometers which enable us to\ndetermine the local electron temperature in a mesoscopic metallic sample, we\nhave obtained quantitative measurements of the low temperature field and\ntemperature dependent thermopower of Andreev interferometers. As in previous\nexperiments, the thermopower is found to oscillate as a function of magnetic\nfield. The temperature dependence of the thermopower is nonmonotonic, with a\nminimum at a temperature of $\\simeq0.5$ K. These results are discussed from the\nperspective of Andreev reflection at the normal-metal/superconductor interface.",
        "positive": "Ellipticity and Dissipation Effects in Magnon Spin Valves: We consider alignment-dependent spin and heat transport across a magnon spin\nvalve in the tunneling regime, i.e., a junction consisting of two weakly\ncoupled ferromagnetic insulators. We determine the difference in spin and heat\nconductance between the parallel and antiparallel configuration of the\nmagnetization direction. The dependence of these conductances on both the\nGilbert damping and ellipticity is studied. We find that both magnon\nellipticity and dissipation open channels for magnons to tunnel through in the\nantiparallel configuration. Our results highlight an important difference\nbetween electronic and magnon spin transport in spin-valve structures and may\nbe important for the development of devices based on magnetic insulators."
    },
    {
        "anchor": "Hanle Effect near Boundaries: The Hanle effect describes suppression of spin polarization due to precession\nin a magnetic field. This is a standard spintronics tool and it gives access to\nthe spin lifetime of samples in which spins are generated homogeneously. We\nexamine the Hanle effect when spins are generated at a boundary of a diffusive\nsample by the extrinsic spin Hall effect. We show that the Hanle curve is\nspatially dependent and that the \"apparent\" spin lifetime, given by its inverse\nhalf-width, is shorter near the boundary even if the spin relaxation rate is\nhomogenous.",
        "positive": "Furtive Quantum Sensing Using Matter-Wave Cloaks: We introduce the concept of furtive quantum sensing, demonstrating the\npossibility of concealing quantum objects from matter-waves, while maintaining\ntheir ability to interact and get excited by the impinging particles. This is\nobtained by cloaking, with tailored homogeneous metamaterial layers, quantum\nsystems having internal degrees of freedom. The effect is a low-observable\nquantum sensor with drastically reduced elastic scattering and optimized\nabsorption levels, a concept that opens interesting venues in particle\ndetection, high-efficiency electrical pumping and quantum supercomputing."
    },
    {
        "anchor": "On defect-induced magnetism and bang opening in graphene: We discuss several mechanisms of magnetism and band opening in graphene\nproduced by its hydrogenation and fluorination that can be examined\nexperimentally.",
        "positive": "Electronic transport of a large scale system studied by renormalized\n  transfer matrix method: application to armchair graphene nanoribbons between\n  quantum wires: Study on the electronic transport of a large scale two dimensional system by\nthe transfer matrix method (TMM) based on the Sch\\\"{o}rdinger equation suffers\nfrom the numerical instability. To address this problem, we propose a\nrenormalized transfer matrix method (RTMM) by setting up a set of linear\nequations from U times of multiplication of traditional transfer matrix\n(U=N/S}with N and S being the atom number of length and the transfer step), and\nsmaller S is required for wider systems. Then we solve the above linear\nequations by Gauss elimination method and further optimize to reduce the\ncomputational complexity from O(U^3M^3) to O(UM^3), in which M is the atom\nnumber of the width. Applying RTMM, we study transport properties of large\nscale pure and long-range correlated disordered armchair graphene nanoribbon\n(AGR) (carbon atoms up to 10^6 for pure case) between quantum wire contacts. As\nfor pure AGR, the conductance is superlinear with the Fermi energy and the\nconductance is linear with the width while independent of the length, showing\ncharacteristics of ballistic transport. As for disordered AGR with long-range\ncorrelation, there is metal-insulator transition induced by the correlation\nstrength of disorder. It is straightforward to extend RTMM to investigate\ntransport in large scale system with irregular structure."
    },
    {
        "anchor": "Butterfly-shaped magnetoresistance in triangular-lattice antiferromagnet\n  Ag$_2$CrO$_2$: Spintronic devices using antiferromagnets (AFMs) are promising candidates for\nfuture applications. Recently, many interesting physical properties have been\nreported with AFM-based devices. Here we report a butterfly-shaped\nmagnetoresistance (MR) in a micrometer-sized triangular-lattice antiferromagnet\nAg$_2$CrO$_2$. The material consists of two-dimensional triangular-lattice\nCrO$_2$ layers with antiferromagnetically coupled $S$ = 3/2 spins and Ag$_2$\nlayers with high electrical conductivity. The butterfly-shaped MR appears only\nwhen the magnetic field is applied perpendicularly to the CrO$_2$ plane with\nthe maximum MR ratio ($\\approx$ 15%) at the magnetic ordering temperature.\nThese features are distinct from those observed in conventional magnetic\nmaterials. We propose a theoretical model where fluctuations of partially\ndisordered spins with the Ising anisotropy play an essential role in the\nbutterfly-shaped MR in Ag$_2$CrO$_2$.",
        "positive": "Effect of piezoelectric substrate on phonon-drag thermopower in\n  monolayer graphene: The phonon-drag thermopower is studied in monolayer graphene on a\npiezoelectric substrate. The phonon-drag contribution S^g_PA from the extrinsic\npotential of piezoelectric surface acoustic (PA) phonons of a piezoelectric\nsubstrate (GaAs) is calculated as a function of temperature T and electron\nconcentration n_s. At very low temperature, S^g_PA is found to be much greater\nthan S^g_DA of the intrinsic deformation potential of acoustic (DA) phonons of\nthe graphene. There is a crossover of S^g_PA and S^g_DA at around ~5 K. In\ngraphene samples of about >10 um size, we predict S_g ~20 uV at 10 K, which is\nmuch greater than the diffusion component of the thermopower and can be\nexperimentally observed. In the Bloch-Gruneisen (BG) regime T and n_s\ndependence are, respectively, given by the power laws S^g_PA (S^g_DA) ~\nT^2(T^3) and S^g_PA, S^g_DA ~ n_s^(-1/2). The T (n_s) dependence is the\nmanifestation of the two-dimensional phonons (Dirac phase of the electrons).\nThe effect of the screening is discussed. Analogous to Herring's law (S_g mu_p\n~T^-1), we predict a new relation S_g mu_p ~n_s^0, where mu_p is the\nphonon-limited mobility. We suggest that n_s dependent measurements will play a\nmore significant role in identifying the Dirac phase and the effect of\nscreening."
    },
    {
        "anchor": "A minimal integer automaton behind crystal plasticity: Power law fluctuations and scale free spatial patterns are known to\ncharacterize steady state plastic flow in crystalline materials. In this Letter\nwe study the emergence of correlations in a simple Frenkel-Kontorova (FK) type\nmodel of 2D plasticity which is largely free of arbitrariness, amenable to\nanalytical study and is capable of generating critical exponents matching\nexperiments. Our main observation concerns the possibility to reduce continuum\nplasticity to an integer valued automaton revealing inherent discreteness of\nthe plastic flow.",
        "positive": "Ultra-high mobility two-dimensional electron gas in a SiGe/Si/SiGe\n  quantum well: We report the observation of an electron gas in a SiGe/Si/SiGe quantum well\nwith maximum mobility up to 240 m^2/Vs, which is noticeably higher than\npreviously reported results in silicon-based structures. Using SiO, rather than\nAl_2O_3, as an insulator, we obtain strongly reduced threshold voltages close\nto zero. In addition to the predominantly small-angle scattering well known in\nthe high-mobility heterostructures, the observed linear temperature dependence\nof the conductivity reveals the presence of a short-range random potential."
    },
    {
        "anchor": "Magnon decay theory of Gilbert damping in metallic antiferromagnets: Gilbert damping is a key property governing magnetization dynamics in ordered\nmagnets. We present a theoretical study of intrinsic Gilbert damping induced by\nmagnon decay in antiferromagnetic metals through $s$-$d$ exchange interaction.\nOur theory delineates the qualitative features of damping in metallic\nantiferromagnets owing to their bipartite nature, in addition to providing\nanalytic expressions for the damping parameters. Magnon-induced intraband\nelectron scattering is found to predominantly cause magnetization damping,\nwhereas the N\\'eel field is found to be damped via disorder. Depending on the\nconduction electron band structure, we predict that magnon-induced interband\nelectron scattering around band crossings may be exploited to engineer a strong\nN\\'eel field damping.",
        "positive": "Gate Tunable In- and Out-Of-Plane Spin-Orbit Coupling and Spin Splitting\n  Anisotropy at LaAlO3/SrTiO3 (110) Interface: Manipulating spin-orbit coupling (SOC) is important for devices such as\nspin-orbit torque based memory and its understanding is neccessary to answer\nseveral fundamental open questions in triplet state superconductivity,\ntopological insulators and Majorana fermions. Here we report spin splitting of\n25 meV at the LaAlO3/SrTiO3 (110) interface for in-plane spins at a current\ndensity of 1.4x104 A/cm2, which is large compared to that found in\nsemiconductor heterostructures or the LaAlO3/SrTiO3 (100) interface, and in\naddition it is anisotropic. The anisotropy arises from the difference in\nelectron effective mass along the [001] and [1-10] directions. Our study\npredicts a spin splitting energy > 1000 meV at a current density of 107 A/cm2,\nwhich is enormous compared to metallic systems and will be an ideal spin\npolarized source. In addition to the in-plane effect, there is an unexpected\ngate-tunable out-of-plane SOC at the LaAlO3/SrTiO3 (110) interface when the\nspins lie out-of-plane due to broken symmetry in the plane of the interface. We\ndemonstrate that this can be manipulated by varying the LaAlO3 thickness\nshowing that this interface can be engineered for spin-orbit torque devices."
    },
    {
        "anchor": "THz conductivity of graphene on boron nitride: The conductivity of graphene on a boron nitride substrate exhibits features\nin the terahertz (THz) and infrared (IR) frequency regimes that are associated\nwith the periodic moir\\'e pattern formed by the weakly coupled two-dimensional\nmaterials. The THz and IR features are strongest when the two honeycomb\nlattices are orientationally aligned, and in this case are Pauli blocked unless\nthe Fermi level is close to $\\pm 150$ meV relative to the graphene sheet Dirac\npoint. Because the transition energies between moir\\'e bands formed above the\nDirac point are small, ac conductivity features in n-doped graphene tend to be\noverwhelmed by the Drude peak. The substrate-induced band splitting is larger\nat energies below the Dirac point, however, and can however lead to sharp\nfeatures at THz and IR frequencies in p-doped graphene. In this Letter we focus\non the strongest few THz and IR features, explaining how they arise from\ncritical points in the moir\\'e-band joint density-of-states, and commenting on\nthe interval of Fermi energy over which they are active.",
        "positive": "Time dependent quantum transport through Kondo correlated quantum dots: In this article, we review recent work about time dependent quantum transport\nthrough a quantum dot in Kondo regime. This represents a major step towards\ndesigning next generation transistors that are expected to replace current\nMOSFET's in a few years. We first discuss the effects of the density of states\nof gold contacts on the instantaneous conductance of an asymmetrically coupled\nquantum dot that is abruptly moved into Kondo regime via a gate voltage. Next,\nwe investigate the effect of strong electron-phonon coupling on the dot on the\ninstantaneous conductance. Finally, we discuss thermoelectric effects using\nlinear response Onsager relations for a quantum dot that is either abruptly\nmoved into Kondo regime or driven sinusoidally via a gate voltage. We explain\nencountered peculiarities in transport based on the behaviour of the density of\nstates of the dot and the evolution of the Kondo resonance."
    },
    {
        "anchor": "Quantized Thermal Hall Conductance and the Topological Phase Diagram of\n  a Superconducting Bismuth Bilayer: Two dimensional topological superconductors with chiral edge modes are\npredicted to posses a quantized thermal Hall effect proportional to the Chern\nnumber, exactly half that for chiral topological insulators. However not much\nwork has been done in identifying the quantized heat conductance in the\nliterature, even for some of the standard models of topological\nsuperconductivity. Here we introduce a model based on a proximity induced\nsuperconducting Bismuth bilayer, and directly calculate the thermal Hall\nconductance of this lattice model. This model serves as a demonstration of the\nstate of the art possible in such a calculation, as well as introducing an\ninteresting paradigmatic topological superconductor with a rich phase diagram.\nWe demonstrate the quantized thermal Hall plateaus in several different\ntopological phases, and compare this to numerical calculations of the Chern\nnumber, as well as analytical calculations of the Chern number's parity\ninvariant. We demonstrate that it is possible to get a reasonable topological\nphase diagram from the quantized thermal Hall calculations. The technique used\ncan be applied to wide range of models directly in real space.",
        "positive": "The universal definition of spin current: The spin current $J_{S}$, orbit angular momentum current $J_{L}$ and total\nangular momentum current $J_{J}$ in a dyad form have been universally defined\naccording to quantum electrodynamics. Their conservation quantities and the\ncontinuity equations have been discussed in different cases. Non-relativistic\napproximation forms are deduced in order to explain their physical meanings,\nand to analyze some experiment results. The spin current of helical edge states\nin HgTe/CdTe quantum wells is calculated to demonstrate the properties of spin\ncurrent on the two dimensional quantum spin-Hall system. A generalized\nspin-orbit coupling term in the semiconductoring media is deduced based on the\ntheory of the electrodynamics in the moving media. We recommend to use the\neffective total angular momentum current instead of the pure spin current to\ndescribe the polarizing distribution and transport phenomena in spintronic\nmedia."
    },
    {
        "anchor": "High fidelity feed-back assisted parity measurement in circuit QED: We analyze a two qubit parity measurement based on dispersive read-out in\ncircuit quantum electrodynamics. The back-action on the qubits has two\nqualitatively different contributions. One is an unavoidable dephasing in one\nof the parity subspaces, arising during the transient time of switching on the\nmeasurement. The other part is a stochastic rotation of the phase in the same\nsubspace, which persists during the whole measurement. The latter can be\ndetermined from the full measurement record, using the method of state\nestimation. Our main result is that the outcome of this phase determination\nprocess is {\\em independent} of the initial state in the state estimation\nprocedure. The procedure can thus be used in a measurement situation, where the\ninitial state is unknown. We discuss how this feed-back method can be used to\nachieve a high fidelity parity measurement for realistic values of the\ncavity-qubit coupling strength. Finally, we discuss the robustness of the\nfeed-back procedure towards errors in the measurement record.",
        "positive": "The probability for wave packet to remain in a disordered cavity: We show that the probability that a wave packet will remain in a disordered\ncavity until the time $t$ decreases exponentially for times shorter than the\nHeisenberg time and log-normally for times much longer than the Heisenberg\ntime. Our result is equivalent to the known result for time-dependent\nconductance; in particular, it is independent of the dimensionality of the\ncavity. We perform non-perturbative ensemble averaging over disorder by making\nuse of field theory. We make use of a one-mode approximation which also gives\nan interpolation formula (arccosh-normal distribution) for the probability to\nremain. We have checked that the optimal fluctuation method gives the same\nresult for the particular geometry which we have chosen. We also show that the\nprobability to remain does not relate simply to the form-factor of the delay\ntime. Finally, we give an interpretation of the result in terms of path\nintegrals. PACS numbers: 73.23.-b, 03.65.Nk"
    },
    {
        "anchor": "Quantum computation with three-electron double quantum dots at an\n  optimal operation point: The author analyzes quantum computation with the hybrid qubit (HQ) that is\nencoded using the three-electron configuration of a double quantum dot. All\ngate operations are controlled with electric signals, while the qubit remains\nat an optimal operation point that is insensitive to noise. An effective\nsingle-qubit description is derived, and two-qubit interactions are suggested\nusing Coulomb and exchange interactions. Universal quantum control is described\nand numerically simulated using realistic parameters for HQs in Si and GaAs.\nHigh-fidelity quantum computing at the threshold of quantum error correction is\npossible if the Coulomb interactions between the HQs stay weak.",
        "positive": "Edge states in bilayer graphene in a magnetic field: Edge states in biased bilayer graphene in a magnetic field are studied within\nthe four-band continuum model. The analysis is done for the semi-infinite\ngraphene plane and for the graphene ribbon of a finite width, in the cases of\nzigzag and armchair edges. Exact dispersion equations for the edge states and\nanalytic expressions for their wave functions are written in terms of the\nparabolic cylinder functions. The spectrum of edge states for each type of the\nboundary conditions is found by numerically solving the corresponding\ndispersion equations. The low-energy modes localized at zigzag edges are\nexplored in detail."
    },
    {
        "anchor": "L-valley Electron Spin Dynamics in GaAs: Optical orientation experiments have been performed in GaAs epilayers with\nphotoexcitation energies in the 3 eV region yielding the photogeneration of\nspin-polarized electrons in the satellite L valley. We demonstrate that a\nsignificant fraction of the electron spin memory can be conserved when the\nelectron is scattered from the L to the $\\Gamma$ valley following an energy\nrelaxation of several hundreds of meV. Combining these high energy\nphoto-excitation experiments with time-resolved photoluminescence spectroscopy\nof $\\Gamma$ valley spin-polarized photogenerated electrons allows us to deduce\na typical L valley electron spin relaxation time of 200 fs, in agreement with\ntheoretical calculations.",
        "positive": "Magnetic coherent tunnel junctions with periodic grating barrier: A new spintronic theory has been developed for the magnetic tunnel junction\n(MTJ) with single-crystal barrier. The barrier will be treated as a diffraction\ngrating with intralayer periodicity, the diffracted waves of tunneling\nelectrons thus contain strong coherence, both in charge and especially in spin.\nThe theory can answer the two basic problems present in MgO-based MTJs: (1) Why\ndoes the tunneling magnetoresistance (TMR) oscillate with the barrier\nthickness? (2) Why is the TMR still far away from infinity when the two\nelectrodes are both half-metallic? Other principal features of TMR can also be\nexplained and reproduced by the present work. It also provides possible ways to\nmodulate the oscillation of TMR, and to enhance TMR so that it can tend to\ninfinity. Within the theory, the barrier, as a periodic diffraction grating,\ncan get rid of the confinement in width, it can vary from nanoscale to\nmicroscale. Based on those results, a future-generation MTJ is proposed where\nthe three pieces can be fabricated separately and then assembled together, it\nis especially appropriate for the layered materials, e.g., MoS2 and graphite,\nand most feasible for industries."
    },
    {
        "anchor": "Fractional quantum Hall states of atoms in optical Lattices: We describe a method to create fractional quantum Hall states of atoms\nconfined in optical lattices. We show that the dynamics of the atoms in the\nlattice is analogous to the motion of a charged particle in a magnetic field if\nan oscillating quadrupole potential is applied together with a periodic\nmodulation of the tunneling between lattice sites. We demonstrate that in a\nsuitable parameter regime the ground state in the lattice is of the fractional\nquantum Hall type and we show how these states can be reached by melting a Mott\ninsulator state in a super lattice potential. Finally we discuss techniques to\nobserve these strongly correlated states.",
        "positive": "Structural distortions in monolayers of binary semiconductors: We examine the structural properties of free standing II-VI and III-V\nsemiconductors at the monolayer limit within first principle density functional\ntheory calculations. A non-polar buckled structure was found to be favoured\nover a polar buckled structure. While an obvious reason for this may be traced\nto the contribution from dipole dipole interactions present in the polar\nstructure which would destabilize it with respect to the nonpolar structure,\nCoulomb interactions between electrons on the cations and anions are found to\nbe the reason for the nonpolar structure to be favoured. A route to tune the\nCoulomb interaction between the electrons on the cations and anions is through\nbiaxial tensile strain. This allows for a planar graphitic phase in CdS to be\nstabilized at just 2\\% tensile strain. Strain also shifts the valence band\nmaximum from the $\\Gamma$ point to the K point opening up opportunities for\nexploring spin-valley physics in these materials."
    },
    {
        "anchor": "Transverse Thermoelectric Conductivity of Bilayer Graphene in Quantum\n  Hall Regime: We performed electric and thermoelectric transport measurements of bilayer\ngraphene in a magnetic field up to 15 Tesla. The transverse thermoelectric\nconductivity $\\rm\\alpha_{xy}$, determined from four transport coefficients,\nattains a peak value of $\\rm\\alpha_{xy, peak}$ whenever chemical potential lies\nin the center of a Landau level. The temperature dependence of $\\rm\\alpha_{xy,\npeak}$ is dictated by the disorder width $\\rm W_L$. For $\\rm k_BT/W_L\\leq$0.2,\n$\\rm\\alpha_{xy, peak}$ is nominally linear in temperature, which gives\n$\\rm\\alpha_{xy,peak}/T=0.19 \\pm 0.03 n A/K^2$ independent of the magnetic\nfield, temperature and Landau Level index. At $\\rm k_BT/W_L\\geq$0.5,\n$\\rm\\alpha_{xy, peak}$ saturates to a value close to the predicted universal\nvalue of $\\rm 4\\times(ln2)k_Be/h$ according to the theory of Girvin and Jonson.\nWe remark that an anomaly is found in $\\rm\\alpha_{xy}$ near the charge neutral\npoint, similar to that in single-layer graphene",
        "positive": "Pressure-dependent Intermediate Magnetic Phase in Thin Fe$_3$GeTe$_2$\n  Flakes: We investigated the evolution of ferromagnetism in layered Fe$_3$GeTe$_2$\nflakes under different pressures and temperatures using in situ magnetic\ncircular dichroism (MCD) spectroscopy. We found that the rectangle shape of\nhysteretic loop under an out-of-plane magnetic field sweep can sustain below 7\nGPa. Above that pressure, an intermediate state appears at low temperature\nregion signaled by an 8-shaped skew hysteretic loop. Meanwhile, the coercive\nfield and Curie temperature decrease with increasing pressures, implying the\ndecrease of the exchange interaction and the magneto-crystalline anisotropy\nunder pressures. The intermediate phase has a labyrinthine domain structure,\nwhich is attributed to the increase of ratio of exchange interaction to\nmagneto-crystalline anisotropy based on Jagla's theory. Moreover, our\ncalculation results reveal a weak structural transition around 6 GPa, which\nleads to a drop of the magnetic momentum of Fe ions."
    },
    {
        "anchor": "Magnetic field-induced control of transport in multiterminal focusing\n  quantum billiards: By exploring the four-terminal transmission of a semi-elliptic open quantum\nbilliard in dependence of its geometry and an applied magnetic field, it is\nshown that a controllable switching of currents between the four terminals can\nbe obtained. Depending on the eccentricity of the semi-ellipse and the width\nand placement of the leads, high transmittivity at zero magnetic field is\nreached either through states guided along the curved boundary or focused onto\nthe straight boundary of the billiard. For small eccentricity, attachment of\nleads at the ellipse foci can yield optimized corresponding transmission, while\ndepartures from this behavior demonstrate the inapplicability of classical\nconsiderations in the deep quantum regime. The geometrically determined\ntransmission is altered by the phase-modulating and deflecting effect of the\nmagnetic field, which switches the pairs of leads connected by high\ntransmittivity. It is shown that the elliptic boundary is responsible for these\nvery special transport properties. At higher field strengths edge states form\nand the multiterminal transmission coefficients are determined by the topology\nof the billiard. The combination of magnetotransport with geometrically\noptimized transmission behavior leads to an efficient control of the current\nthrough the multiterminal structure.",
        "positive": "Phase diagram and validity of one-parameter scaling near the\n  two-dimensional metal-insulator transition: We explore the scaling description for a two-dimensional metal-insulator\ntransition (MIT) of electrons in silicon. Near the MIT, $\\beta_{T}/p =\n(-1/p)d(\\ln g)/d(\\ln T)$ is universal (with $p$, a sample dependent exponent,\ndetermined separately; $g$--conductance, $T$--temperature). We obtain the\ncharacteristic temperatures $T_0$ and $T_1$ demarking respectively the quantum\ncritical region and the regime of validity of single parameter scaling in the\nmetallic phase, and show that $T_1$ vanishes as the transition is approached.\nFor $T<T_1$, the scaling of the data requires a second parameter. Moreover, all\nof the data can be described with two-parameter scaling at all densities --\neven far from the transition."
    },
    {
        "anchor": "Strong back-action of a linear circuit on a single electronic quantum\n  channel: What are the quantum laws of electricity in mesoscopic circuits? This very\nfundamental question has also direct implications for the quantum engineering\nof nanoelectronic devices. Indeed, when a quantum coherent conductor is\ninserted into a circuit, its transport properties are modified. In particular,\nits conductance is reduced because of the circuit back-action. This phenomenon,\ncalled environmental Coulomb blockade, results from the granularity of charge\ntransfers across the coherent conductor. Although extensively studied for a\ntunnel junction in a linear circuit, it is only fully understood for arbitrary\nshort coherent conductors in the limit of small circuit impedances and small\nconductance reduction. Here, we investigate experimentally the strong\nback-action regime, with a conductance reduction of up to 90%. This is achieved\nby embedding a single quantum channel of tunable transmission in an adjustable\non-chip circuit of impedance comparable to the resistance quantum $R_K=h/e^2$\nat microwave frequencies. The experiment reveals important deviations from\ncalculations performed in the weak back-action framework, and matches with\nrecent theoretical results. From these measurements, we propose a generalized\nexpression for the conductance of an arbitrary quantum channel embedded in a\nlinear circuit.",
        "positive": "Computational analysis of NM-polynomial based topological indices and\n  graph-entropies of carbon nanotube Y-junctions: Carbon nanotube Y-junctions are of great interest to the next generation of\ninnovative multi-terminal nanodevices. Topological indices are\ngraph-theoretically based parameters that describe various structural\nproperties of a chemical molecule. The entropy of a graph is a topological\ndescriptor that serves to characterize the complexity of the underlying\nmolecular graph. The concept of entropy is a physical property of a\nthermodynamic system. Graph entropies are the essential thermophysical\nquantities defined for various graph invariants and are applied to measure the\nheterogeneity and relative stabilities of molecules. In this paper, several\nneighborhood degree sum-based topological indices including graph-based\nentropies of carbon nanotube Y-junction graphs are computed."
    },
    {
        "anchor": "Nonreciprocal Dzyaloshinskii-Moriya magnetoacoustic waves: We study the interaction of surface acoustic waves with spin waves in\nultra-thin CoFeB/Pt bilayers. Due to the interfacial Dzyaloshinskii-Moriya\ninteraction (DMI), the spin wave dispersion is non-degenerate for oppositely\npropagating spin waves in CoFeB/Pt. In combination with the additional\nnonreciprocity of the magnetoacoustic coupling itself, highly nonreciprocal\nacoustic wave transmission through the magnetic film is observed. We\nsystematically characterize the magnetoacoustic wave propagation in a thickness\nseries of CoFeB($d$)/Pt samples as a function of magnetic field magnitude and\ndirection, and at frequencies up to 7 GHz. We quantitatively model our results\nto extract the strength of the DMI and magnetoacoustic driving fields.",
        "positive": "Valley Degeneracies in (111) Silicon Quantum Wells: (111) Silicon quantum wells have been studied extensively, yet no convincing\nexplanation exists for the experimentally observed breaking of 6 fold valley\ndegeneracy into 2 and 4 fold degeneracies. Here, systematic sp3d5s*\ntight-binding and effective mass calculations are presented to show that a\ntypical miscut modulates the energy levels which leads to breaking of 6 fold\nvalley degeneracy into 2 lower and 4 raised valleys. An effective mass based\nvalley-projection model is used to determine the directions of valley-minima in\ntight-binding calculations of large supercells. Tight-binding calculations are\nin better agreement with experiments compared to effective mass calculations."
    },
    {
        "anchor": "Exploiting femtosecond laser exposure for additive and subtractive\n  fabrication of functional materials: A Route to designer 3D Magnetic\n  Nanostructures: Three-dimensional nanostructured functional materials are important systems,\nallowing new means to intricately control electromagnetic properties. A key\nproblem is realising a 3D printing methodology upon the nanoscale that can\nyield a range of functional materials. In this letter, it is shown that\ntwo-photon lithography when combined with femtosecond machining of sacrificial\nlayers, can be used to realise such a vision and produce 3D functional\nnanomaterials of complex geometry. This is demonstrated by fabricating 3D\nmagnetic nanowires that exhibit controlled domain wall injection and\npropagation. Secondly, we fabricate large scale 3D artificial spin-ice\nstructures whose complex switching can be probed using optical magnetometry. We\nshow that by careful analysis of the magneto-optical Kerr effect signal and by\ncomparison with micro-magnetic simulations, depth dependent switching\ninformation can be obtained from the 3DASI lattice. The work paves the way to\nnew materials, which exploit additional physics provided by non-trivial 3D\ngeometries.",
        "positive": "Josephson junction microwave amplifier in self-organized noise\n  compression mode: The fundamental noise limit of a phase-preserving amplifier at frequency\n$\\omega /2\\pi $ is the standard quantum limit $T_{q}=\\hbar \\omega /2k_{B}$. In\nthe microwave range, the best candidates have been amplifiers based on\nsuperconducting quantum interference devices (reaching the noise temperature\n$T_{n} \\sim 1.8 T_{q}$ at 700 MHz), and non-degenerate parametric amplifiers\n(reaching noise levels close to the quantum limit $T_{n}\\approx T_{q}$ at 8\nGHz). We introduce a new type of an amplifier based on the negative resistance\nof a selectively damped Josephson junction. Noise performance of our amplifier\nis limited by mixing of quantum noise from Josephson oscillation regime down to\nthe signal frequency. Measurements yield nearly quantum-limited operation,\n$T_{n}=(3.2\\pm 1.0) T_{q}$ at 2.8 GHz, owing to self-organization of the\nworking point. Simulations describe the characteristics of our device well and\nindicate potential for wide bandwidth operation."
    },
    {
        "anchor": "Design of an experiment to study the motion of nano-liquid helium\n  droplets: One of the most important task in physics today is to merge quantum mechanics\nand general relativity into one framework. And the main barrier in this task is\nthat we lack quantum gravitational phenomena in experiments. An important way\nto get quantum gravitational phenomena is to study quantum effects in a\nmacro-scale system in which gravity will play a role. In this article, we want\nto study dynamics of a possible macro-scale system: liquid helium droplets with\nradius of 100nm under low temperature and low pressure. Our idea is to observe\nthe interference phenomenon of this system and find the similarities and\ndifference between it and quantum system. We gave a practical experiment design\nto observe the interference, including a possible method to realize an\napproximate square barrier. We also gave an illustration on what a quantum or a\nclassical interferogram of our system looks like theoretically.",
        "positive": "Modern theory of magnetic breakdown: The modern semiclassical theory of a Bloch electron in a magnetic field\nencompasses the orbital magnetization and geometric phase. Beyond this\nsemiclassical theory lies the quantum description of field-induced tunneling\nbetween semiclassical orbits, known as magnetic breakdown. Here, we synthesize\nthe modern semiclassical notions with quantum tunneling -- into a single\nBohr-Sommerfeld quantization rule that is predictive of magnetic energy levels.\nThis rule is applicable to a host of topological solids with \\emph{unremovable}\ngeometric phase, that also \\emph{unavoidably} undergo breakdown. A notion of\ntopological invariants is formulated that nonperturbatively encode tunneling,\nand is measurable in the de-Haas-van-Alphen effect. Case studies are discussed\nfor topological metals near a metal-insulator transition and over-tilted Weyl\nfermions."
    },
    {
        "anchor": "Current-induced skyrmion dynamics in constricted geometries: Magnetic skyrmions, vortex-like swirling spin structures with quantized\ntopological number, observed in chiral magnets, are appealing for potential\napplications in spintronics because it is possible to control their motion with\nultralow current density. In order to realise skyrmion-based spintronic\ndevices, it is essential to understand the skyrmion motions in confined\ngeometries. Here we show by micromagnetic simulations that the current-induced\nmotion of skyrmions in the presence of geometrical boundaries is very different\nfrom that in an infinite plane. In a channel with finite width, the transverse\nconfinement results in steady state characteristics of the skyrmion velocity as\na function of current similar to those of domain walls in ferromagnets, whereas\nthe transient behaviour depends on the initial distance of the skyrmion from\nthe boundary. In addition, we show that single skyrmions can be created by\nelectric current in a simple constricted geometry of a plate-shaped specimen of\nsuitable size and geometry. These findings could guide the design of\nskyrmion-based devices, in which skyrmions are used as information carriers.",
        "positive": "Algorithmic Analysis for Reproducible Thickness Determination of\n  Semiconducting 2D Nanomaterials based on UV/VIS Extinction Spectroscopy: Rapid and reliable analysis of liquid dispersions of 2D materials is\nessential for fully harnessing their potential, allowing size and quality\nvalidation before subsequent processing or device fabrication. Existing UV/VIS\nextinction spectroscopy-based metrics, particularly those related to thickness,\nhave shown promise but rely on manual data processing, which can introduce\nirreproducibility and user errors. To address this challenge and enable uniform\nanalysis across laboratories, we have developed a freely available program for\nthe reproducible analysis of nanosheet dispersions. Specifically, we apply a\nsmoothing routine to the spectral data, take the second derivative and use\nintegral areas to find the wavelength of exciton transitions. Our program\nenables rapid measurement of nanosheet concentration, length and thickness by\nUV/VIS spectroscopy and we have refined thickness metrics for eight common 2D\nnanomaterials. The program and methodology are freely available for use, and\nallow metrics for new materials to be implemented easily in the future."
    },
    {
        "anchor": "Entropy production in photovoltaic-thermoelectric nanodevices from the\n  non-equilibrium Green's function formalism: We derive the expressions of photon energy and particle currents inside an\nopen nanosystem interacting with light using non-equilibrium Green's functions.\nThe model allows different temperatures for the electron reservoirs, which\nbasically defines a photovoltaic-thermoelectric hybrid. Thanks to these\nexpressions, we formulate the steady-state entropy production rate to assess\nthe efficiency of reversible photovoltaic-thermoelectric nanodevices. Next,\nquantum dot based nanojunctions are closely examined. We show that entropy\nproduction is always positive when one considers spontaneous emission of\nphotons with a specific energy, while in general the emission spectrum is\nbroadened, notably for strong coupling to reservoirs. In this latter case, when\nthe emission is integrated over all the energies of the spectrum, we find that\nentropy production can reach negative values. This result provides matter to\nquestion the second law of thermodynamics for interacting nanosystems beyond\nthe assumption of weak coupling.",
        "positive": "Planar Hall effect in topological Weyl and nodal line semimetals: Using symmetry analysis and semiclassical Boltzmann equation, we\ntheoretically explore the planar Hall effect (PHE) in three-dimensional\nmaterials. We demonstrate that PHE is a general phenomenon that can occur in\nvarious systems regardless of band topology. Both the Lorentz force and Berry\ncurvature effects can induce significant PHE, and the leading contributions of\nboth effects linearly depend on the electric and magnetic fields. The Lorentz\nforce and Berry curvature PHE coefficient possess only antisymmetric and\nsymmetric parts, respectively. Both contributions respect the same crystalline\nsymmetry constraints but differ under time-reversal symmetry. Remarkably, for\ntopological Weyl semimetal, the Berry curvature PHE coefficient is a constant\nthat does not depends on the Fermi energy, while the Lorentz force contribution\nlinearly increases with the Fermi energy, resulting from the linear dispersion\nof the Weyl point. Furthermore, we find that the PHE in topological nodal line\nsemimetals is mainly induced by the Lorentz force, as the Berry curvature in\nthese systems vanishes near the nodal line. Our study not only highlights the\nsignificance of the Lorentz force in PHE, but also reveals its unique\ncharacteristics, which will be beneficial for determining the Lorentz force\ncontribution experimentally."
    },
    {
        "anchor": "Edge states and the integer quantum Hall conductance in spin-chiral\n  ferromagnetic kagome lattice: We investigate the chiral edge states in the two-dimensional ferromagntic\nkagom\\'{e} lattice with spin anisotropies included. The system is periodic in\nthe $x$ direction but has two edges in the $y$ direction. The Harper equation\nfor solving the energies of edge states is derived. We find that there are two\nedge states in each bulk energy gap, corresponding to two zero points of the\nBloch function on the complex-energy Riemann surface (RS). The edge-state\nenergy loops parametrized by the momentum $k_{x}$ cross the holes of the RS.\nWhen the Fermi energy lies in the bulk energy gap, the quantized Hall\nconductance is given by the winding number of the edge states across the holes,\nwhich reads as $\\sigma_{xy}^{\\text{edge}}$=$-\\frac{e^{2}}{h}% $sgn$(\\sin\\phi)\n$, where $\\phi$ is the spin chiral parameter (see text). This result keeps\nconsistent with that based on the topological bulk theory.",
        "positive": "Wave functions for a toroidal quantum dot in the presence of an axially\n  symmetric magnetic field: transition from ring to bulk states as a function\n  of aspect ratio: A basis set expansion is employed to calculate spectra and eigenstates of\ncharge carriers within a toroidal volume characterized by major radius $R$ and\nminor radius $a$ immersed in an azimuthally symmetric magnetic field. The\nangular variables appearing in the Schrodinger equation are eliminated by\ncontour methods, yielding effective potentials that reduce computational time\nby a large factor. An approximation formula for the single particle spectrum is\npresented that allows efficient construction of the partition function\nnecessary for rapid calculation of thermodynamic quantities. The heat capacity\nfrom as a function of torus aspect ratio and temperature is calculated. The\ntransition from ring-type to bulk-type behavior of the heat capacity is\npresented."
    },
    {
        "anchor": "Persistent entanglement of valley exciton qubits in transition metal\n  dichalcogenides integrated into a bimodal optical cavity: We report dissipative dynamics of two valley excitons residing in the $K$ and\n$K^\\prime$-valleys of bare WSe$_2$ monolayer and the one being integrated into\na bimodal optical cavity. In the former, only when the exciton-field detunings\nin the $K$ and $K^\\prime$-valleys are rigorously equal (resonant detuning),\npartially entangled stationary states can be created. Otherwise the concurrence\nof exciton qubits turns to zero. Remarkably, in the latter (the WSe$_2$\nmonolayer in a bimodal optical cavity), the transfers of entanglement from one\nsubsystem (exciton/light) to the other (light/exciton) take place. Hence a\nfinite stationary concurrence of exciton qubits is always generated,\nindependent of whether the exciton-field detuning in two valleys is resonant or\nnon-resonant. In addition, it can even reach as high as 1 (maximally entangled\nstate of two valley excitons). Since there no real system which has a strictly\nresonant detuning, an immersion of the WSe$_2$ monolayer in a bimodal optical\ncavity provides an opportunity to overcome the challenge facing by the bare\nWSe$_2$, opening a novel realm of potential qubits.",
        "positive": "Flip-chip-based fast inductive parity readout of a planar\n  superconducting island: Properties of superconducting devices depend sensitively on the parity (even\nor odd) of the quasiparticles they contain. Encoding quantum information in the\nparity degree of freedom is central in several emerging solid-state qubit\narchitectures. Yet, accurate, non-destructive, and time-resolved parity\nmeasurement is a challenging and long-standing issue. Here we report on control\nand real-time parity measurement in a superconducting island embedded in a\nsuperconducting loop and realized in a hybrid two-dimensional heterostructure\nusing a microwave resonator. Device and readout resonator are located on\nseparate chips, connected via flip-chip bonding, and couple inductively through\nvacuum. The superconducting resonator detects the parity-dependent circuit\ninductance, allowing for fast and non-destructive parity readout. We resolved\neven and odd parity states with signal-to-noise ratio SNR $\\approx3$ with an\nintegration time of $20~\\mu$s and detection fidelity exceeding 98%. Real-time\nparity measurement showed state lifetime extending into millisecond range. Our\napproach will lead to better understanding of coherence-limiting mechanisms in\nsuperconducting quantum hardware and provide novel readout schemes for hybrid\nqubits."
    },
    {
        "anchor": "Ising-Type Magnetic Ordering in Atomically Thin FePS3: Magnetism in two-dimensional materials is not only of fundamental scientific\ninterest but also a promising candidate for numerous applications. However,\nstudies so far, especially the experimental ones, have been mostly limited to\nthe magnetism arising from defects, vacancies, edges or chemical dopants which\nare all extrinsic effects. Here, we report on the observation of intrinsic\nantiferromagnetic ordering in the two-dimensional limit. By monitoring the\nRaman peaks that arise from zone folding due to antiferromagnetic ordering at\nthe transition temperature, we demonstrate that FePS3 exhibits an Ising-type\nantiferromagnetic ordering down to the monolayer limit, in good agreement with\nthe Onsager solution for two-dimensional order-disorder transition. The\ntransition temperature remains almost independent of the thickness from bulk to\nthe monolayer limit with TN ~118 K, indicating that the weak interlayer\ninteraction has little effect on the antiferromagnetic ordering.",
        "positive": "Magnetic Moment Formation in Quantum Point Contacts: We study the formation of local magnetic moments in quantum point contacts.\nUsing a Hubbard-like model to describe point contacts formed in a two\ndimensional system, we calculate the magnetic moment using the unrestricted\nHartree approximation. We analyze different type of potentials to define the\npoint contact, for a simple square potential we calculate a phase diagram in\nthe parameter space (Coulomb repulsion - gate voltage). We also present an\nanalytical calculation of the susceptibility to give explicit conditions for\nthe occurrence of a local moment, we present a simple scaling argument to\nanalyze how the stability of the magnetic moment depends on the point contact\ndimensions."
    },
    {
        "anchor": "Engineering high quality graphene superlattices via ion milled\n  ultra-thin etching masks: Nanofabrication research pursues the miniaturization of patterned feature\nsize. In the current state of the art, micron scale areas can be patterned with\nfeatures down to ~ 30 nm pitch using electron beam lithography. Our work\ndemonstrates a new nanofabrication technique which allows patterning periodic\nstructures with a pitch down to 16 nm. It is based on focused ion beam milling\nof suspended membranes, with minimal proximity effects typical to electron beam\nlithography. The membranes are then transferred and used as hard etching masks.\nWe benchmark our technique by engineering a superlattice potential in single\nlayer graphene using a thin graphite patterned gate electrode. Our electronic\ntransport characterization shows high quality superlattice properties and a\nrich Hofstadter butterfly spectrum. Our technique opens the path towards the\nrealization of very short period superlattices in 2D materials, comparable to\nthose in natural moire systems, but with the ability to control lattice\nsymmetries and strength. This can pave the way for a versatile solid-state\nquantum simulator platform and the study of correlated electron phases.",
        "positive": "Limits of funneling efficiency in non-uniformly strained 2D\n  semiconductors: Photoexcited electron-hole pairs (excitons) in transition metal\ndichalcogenides (TMDC) experience an effective force when these materials are\nnon-uniformly strained. In the case of strain produced by a sharp tip pressing\nat the center of a suspended TMDC membrane, the excitons are transported to the\npoint of the highest strain at the center of the membrane. This effect, exciton\nfunneling, can be used to increase photoconversion efficiency in TMDC, to\nexplore exciton transport, and to study correlated states of excitons arising\nat their high densities. Here, we analyze the limits of funneling efficiency in\nrealistic device geometries. The funneling efficiency in realistic monolayer\nTMDCs is found to be low, $ <5 \\;\\%$ both at room and low temperatures. This\nresults from dominant diffusion at room temperature and short exciton lifetimes\nat low temperatures. On the other hand, in TMDC heterostructures with long\nexciton lifetimes the funneling efficiency reaches $\\sim 50\\;\\%$ at room\ntemperature, as the exciton density reaches thermal equilibrium in the funnel.\nFinally, we show that Auger recombination limits funneling efficiency for\nintense illumination sources."
    },
    {
        "anchor": "Fractional-quantum-Hall edge electrons and Fermi statistics: We address the quantum statistics of electrons created in the low-energy\nedge-state Hilbert space sector of incompressible fractional quantum Hall\nstates, considering the possibility that they may not satisfy Fermi statistics.\nWe argue that this property is not a priori obvious, and present numerical\nevidence based on finite-size exact-diagonalization calculations that it does\nnot hold in general. We discuss different possible forms for the expression for\nthe electron creation operator in terms of edge boson fields and show that none\nare consistent with our numerical results on finite-size filling-factor-2/5\nstates with short-range electron-electron interactions. Finally, we discuss the\ncurrent body of experimental results on tunneling into quantum Hall edges in\nthe context of this result.",
        "positive": "Spin filter and spin valve in ferromagnetic graphene: We propose and demonstrate that a EuO-induced and top-gated graphene\nferromagnetic junction can be simultaneously operated as a spin filter as well\nas a spin valve. We attribute such a remarkable result to a coexistence of a\nhalf-metal band and a common energy gap for opposite spins in ferromagnetic\ngraphene. We show that, both the spin filter and the spin valve can be\neffectively controlled by a back gate voltage, and they survive for practical\nmetal contacts and finite temperature. Specifically, larger single spin\ncurrents and on-state currents can be reached with contacts with work functions\nsimilar to graphene, and the spin filter can operate at higher temperature than\nthe spin valve."
    },
    {
        "anchor": "Effective-mass theory of collapsed carbon nanotubes: Band structure is theoretically studied in partially flattened carbon\nnanotubes within an effective-mass scheme. Effects of inter-wall interactions\nare shown to be important in non-chiral nanotubes such as zigzag and armchair\nand can essentially be neglected in chiral nanotubes except in the close\nvicinity of non-chiral tubes. In fact, inter-wall interactions significantly\nmodify states depending on relative displacement in the flattened region in\nnon-chiral tubes and can convert semiconducting tubes into metallic and vice\nversa. They diminish rapidly when the chiral angle deviates from that of the\nzigzag or armchair tube, although the decay is slower in the vicinity of\narmchair tubes.",
        "positive": "Spin-State dependent Conductance Switching in Single Molecule-Graphene\n  Junctions: Spin-crossover (SCO) molecules are versatile magnetic switches with\napplications in molecular electronics and spintronics. Downscaling devices to\nthe single-molecule level remains, however, a challenging task since the\nswitching mechanism in bulk is mediated by cooperative intermolecular\ninteractions. Here, we report on electron transport through individual Fe-SCO\nmolecules coupled to few-layer graphene electrodes \\textit{via} $\\pi - \\pi$\nstacking. We observe a distinct bistability in the conductance of the molecule\nand a careful comparison with density functional theory (DFT) calculations\nallows to associate the bistability with a SCO-induced orbital reconfiguration\nof the molecule. We find long spin-state lifetimes that are caused by the\nspecific coordination of the magnetic core and the absence of intermolecular\ninteractions according to our calculations. In contrast with bulk samples, the\nSCO transition is not triggered by temperature but induced by small\nperturbations in the molecule at any temperature. We propose plausible\nmechanisms that could trigger the SCO at the single-molecule level."
    },
    {
        "anchor": "Theory of electron Zitterbewegung in graphene probed by femtosecond\n  laser pulses: We propose an experiment allowing an observation of Zitterbewegung (ZB,\ntrembling motion) of electrons in graphene in the presence of a magnetic field.\nIn contrast to the existing theoretical work we make no assumptions concerning\nshape of the electron wave packet. A femtosecond Gaussian laser pulse excites\nelectrons from the valence $n=-1$ Landau level into three other levels,\ncreating an oscillating electron wave packet with interband and intraband\nfrequencies. Oscillations of an average position of the packet are directly\nrelated to the induced dipole moment and oscillations of the average packet's\nacceleration determine emitted electric field. Both quantities can be measured\nexperimentally. A broadening of Landau levels is included to make the\ndescription of ZB as realistic as possible. Criteria of realization of a ZB\nexperiment are discussed.",
        "positive": "Surface-induced positive planar Hall effect in topological Kondo\n  insulator SmB6 microribbons: Whether the surface states in SmB6 are topological is still a critical issue\nin the field of topological Kondo insulators. In the magneto-transport study of\nsingle crystalline SmB6 microribbons, we have revealed a positive planar Hall\neffect (PHE), the amplitude of which increases dramatically with decreasing\ntemperatures but saturates below 5 K. This positive PHE is ascribed to the\nsurface states of SmB6 and expected to arise from the anisotropy in lifting the\ntopological protection from back-scattering by the in-plane magnetic field,\nthus suggesting the topological nature of surface states in SmB6. On the\ncontrary, a negative PHE is observed for the bulk states at high temperatures,\nwhich is almost three orders of magnitudes weaker than the surface-induced\npositive PHE."
    },
    {
        "anchor": "Characterization and control of charge transfer in a tunnel junction: Charge transfer in a tunnel junction is studied under dc and ac voltage bias\nusing quantum shot noise. Under dc voltage bias $V$, spectral density of noise\nmeasured within a very large bandwidth enables to deduce the current-current\ncorrelator in the time domain by Fourier transform. This correlator exhibits\nregular oscillations proving that electrons try to cross the junction\nregularly, every $h/eV$. Using harmonic and bi-harmonic ac voltage bias, we\nthen show that quasiparticles excitations can be transferred through the\njunction in a controlled way. By measuring the reduction of the excess shot\nnoise, we are able to determine the number of electron-hole pairs surrounding\nthe injected electrons and demonstrate that bi-harmonic voltage pulses realize\nan on-demand electron source with a very small admixture of electron-hole\npairs.",
        "positive": "Finite-frequency-dependent noise of a quantum dot in a magnetic field: We present a detailed study for the finite-frequency current noise of a Kondo\nquantum dot in presence of a magnetic field by using a recently developed real\ntime functional renormalization group approach [Phys. Rev. B $\\mathbf{83}$,\n201303(R) (2011)]. The scaling equations are modified in an external magnetic\nfield; the couplings and non-local current vertices become strongly\nanisotropic, and develop new singularities. Consequently, in addition to the\nnatural emission threshold frequency, $\\hbar\\omega = |eV|$, a corresponding\nsingular behavior is found to emerge in the noise spectrum at frequencies\n$\\hbar \\omega \\approx |eV\\pm B|$. The predicted singularities are measurable\nwith present-day experimental techniques."
    },
    {
        "anchor": "Tuning of Exciton States in a Magnetic Quantum Ring: We have studied the exciton states in a CdTe quantum ring in an external\nmagnetic field containing a single magnetic impurity. We have used the\nmultiband approximation which includes the heavy hole - light hole coupling\neffects. The electron-hole spin interactions and the s, p-d interactions\nbetween the electron, hole and the magnetic impurity are also included. The\nexciton energy levels and optical transitions are evaluated using the exact\ndiagonalization scheme. We show that due to the spin interactions it is\npossible to change the bright exciton state into the dark state and vice versa\nwith the help of a magnetic field. We propose a new route to experimentally\nestimate the s, p-d spin interaction constants.",
        "positive": "Fermions in an anisotropic random magnetic field: We study the localization of fermions in an anisotropic random magnetic field\nin two dimensions. It is assumed that the randomness in a particular direction\nis stronger than those in the other directions. We consider a network model of\nzero field contours, where there are two types of randomness - the random\ntunneling matrix element at the saddle points and unidirectional random\nvariation of the number of fermionic states following zero field contours.\nAfter averaging over the random complex tunneling amplitude, the problem is\nmapped to an SU(2N) random exchange quantum spin chain in the $N \\to 0$ limit.\nWe suggest that the fermionic state becomes critical in an anisotropic fashion."
    },
    {
        "anchor": "The Kondo Resonance Line Shape in Scanning Tunnelling Spectroscopy:\n  Instrumental Aspects: In the scanning tunnelling microscope, the many-body Kondo effect leads to a\nzero-bias feature of the differential conductance spectra of magnetic\nadsorbates on surfaces. The intrinsic line shape of this Kondo resonance and\nits temperature dependence in principle contain valuable information. We use\nmeasurements on a molecular Kondo system, all-trans retinoic acid on Au(111),\nand model calculations to discuss the role of instrumental broadening. The\nmodulation voltage used for the lock-in detection, noise on the sample voltage,\nand the temperature of the microscope tip are considered. These sources of\nbroadening affect the apparent line shapes and render difficult a determination\nof the intrinsic line width, in particular when variable temperatures are\ninvolved.",
        "positive": "Stability and asymptotic interactions of chiral magnetic skyrmions in a\n  tilted magnetic field: Using a general framework, interaction potentials between chiral magnetic\nsolitons in a planar system with a tilted external magnetic field are\ncalculated analytically in the limit of large separation. The results are\ncompared to previous numerical results for solitons with topological charge\n$\\pm 1$. A key feature of the calculation is the interpretation of\nDzyaloshinskii-Moriya interaction (DMI) as a background $SO(3)$ gauge field. In\na tilted field, this leads to a $U(1)$-gauged version of the usual equation for\nspin excitations, leading to a distinctive oscillating interaction profile. We\nalso obtain predictions for skyrmion stability in a tilted field which closely\nmatch numerical observations."
    },
    {
        "anchor": "Analytical expression for Risken-Nummedal-Graham-Haken instability\n  threshold in quantum cascade lasers: We have obtained a closed-form expression for the threshold of\nRisken-Nummedal-Graham-Haken (RNGH) multimode instability in a Fabry-P\\'erot\n(FP) cavity quantum cascade laser (QCL). This simple analytical expression is a\nversatile tool that can easily be applied in practical situations which require\nanalysis of QCL dynamic behavior and estimation of its second threshold. Our\nmodel for a FP cavity laser accounts for the carrier coherence grating and\ncarrier population grating as well as their relaxation due to carrier\ndiffusion. In the model, the RNGH instability threshold is analyzed using a\nsecond-order bi-orthogonal perturbation theory and we confirm our analytical\nsolution by a comparison with the numerical simulations. In particular, the\nmodel predicts a low second threshold in QCLs. This agrees very well with\nexperimental data available in the literature.",
        "positive": "Spectrum of the Andreev Billiard and Giant Fluctuations of the Ehrenfest\n  Time: The density of states in the semiclassical Andreev billiard is theoretically\nstudied and shown to be determined by the fluctuations of the classical\nLyapunov exponent $\\lambda$. The rare trajectories with a small value of\n$\\lambda$ give rise to an anomalous increase of the Ehrenfest time\n$\\tau_E\\approx |\\ln\\hbar|/\\lambda$ and, consequently, to the appearance of\nAndreev levels with small excitation energy. The gap in spectrum is obtained\nand fluctuations of the value of the gap due to different positions of\nsuperconducting lead are considered."
    },
    {
        "anchor": "Watching the coherent birth of polaron pairs in conjugated polymers: Organic semiconductors have the remarkable property that their optical\nexcitation not only generates charge-neutral electron-hole pairs (excitons) but\nalso charge-separated polaron pairs with high yield. The microscopic mechanisms\nunderlying this charge separation have been debated for many years. Here we use\nultrafast two-dimensional electronic spectroscopy to study the dynamics of\npolaron pair formation in a prototypical polymer thin film on a sub-20-fs time\nscale. We observe multi-period peak oscillations persisting for up to about 1\nps as distinct signatures of vibronic quantum coherence at room temperature.\nThe measured two-dimensional spectra show pronounced peak splittings revealing\nthat the elementary optical excitations of this polymer are hybridized\nexciton-polaron-pairs, strongly coupled to a dominant underdamped vibrational\nmode. Coherent vibronic coupling induces ultrafast polaron pair formation,\naccelerates the charge separation dynamics and makes it insensitive to\ndisorder. These findings open up new perspectives for tailoring\nlight-to-current conversion in organic materials.",
        "positive": "Magnetoelectric effects and valley controlled spin quantum gates in\n  transition metal dichalcogenide bilayers: In monolayer group-VI transition metal dichalcogenides (TMDC), charge\ncarriers have spin and valley degrees of freedom, both associated with magnetic\nmoments. On the other hand, the layer degree of freedom in multilayers is\nassociated with electrical polarization. Here, we show that TMDC bilayers offer\nan unprecedented platform to realize a strong coupling between the spin, layer\npseudospin, and valley degrees of freedom of holes. Such coupling not only\ngives rise to the spin Hall effect and spin circular dichroism in inversion\nsymmetric bilayer, but also leads to a variety of magnetoelectric effects\npermitting quantum manipulation of these electronic degrees of freedom.\nOscillating electric and magnetic fields can both drive the hole spin resonance\nwhere the two fields have valley-dependent interference, making possible a\nprototype interplay between the spin and valley as information carriers for\npotential valley-spintronic applications. We show how to realize quantum gates\non the spin qubit controlled by the valley bit."
    },
    {
        "anchor": "Kondo resonance in a multi-probe quantum dot: We present a theoretical analysis of a possible route for directly detecting\nKondo resonances in local density of states (LDOS) of an interacting quantum\ndot. By very weakly couple a third and/or a fourth lead to a two-probe quantum\ndot and measuring differential conductance through these extra links, we show\nthat Kondo peaks directly map onto the differential conductance measured from\nthe third link. We analyze the conditions by which this detection of Kondo\npeaks in LDOS is possible.",
        "positive": "Theory for magnetic-field-driven 3D metal-insulator transitions in the\n  quantum limit: Metal-insulator transitions driven by magnetic fields have been extensively\nstudied in 2D, but a 3D theory is still lacking. Motivated by recent\nexperiments, we develop a scaling theory for the metal-insulator transitions in\nthe strong-magnetic-field quantum limit of a 3D system. By using a\nrenormalization-group calculation to treat electron-electron interactions,\nelectron-phonon interactions, and disorder on the same footing, we obtain the\ncritical exponent that characterizes the scaling relations of the resistivity\nto temperature and magnetic field. By comparing the critical exponent with\nthose in a recent experiment [F. Tang et al., Nature (London) 569, 537 (2019)],\nwe conclude that the insulating ground state was not only a charge-density wave\ndriven by electron-phonon interactions but also coexisting with strong\nelectron-electron interactions and backscattering disorder. We also propose a\ncurrent-scaling experiment for further verification. Our theory will be helpful\nfor exploring the emergent territory of 3D metal-insulator transitions under\nstrong magnetic fields."
    },
    {
        "anchor": "Study of Warm Electron Injection in Double Gate SONOS by Full Band Monte\n  Carlo Simulation: In this paper we investigate warm electron injection in a double gate SONOS\nmemory by means of 2D full-band Monte Carlo simulations of the Boltzmann\nTransport Equation (BTE). Electrons are accelerated in the channel by a\ndrain-to-source voltage VDS smaller than 3 V, so that programming occurs via\nelectrons tunneling through a potential barrier whose height has been\neffectively reduced by the accumulated kinetic energy. Particle energy\ndistribution at the semiconductor/oxide interface is studied for different bias\nconditions and different positions along the channel. The gate current is\ncalculated with a continuum-based post-processing method as a function of the\nparticle distribution obtained from Monte Carlo. Simulation results show that\nthe gate current increases by several orders of magnitude with increasing drain\nbias and warm electron injection can be an interesting option for programming\nwhen short channel effects prohibit the application of larger drain bias.",
        "positive": "Effective dynamics for a spin-1/2 particle constrained to a space curve\n  in an electric and magnetic field: We consider the dynamics of a spin-1/2 particle constrained to move in an\narbitrary space curve with an external electric and magnetic field applied.\nWith the aid of gauge theory, we successfully decouple the tangential and\nnormal dynamics and derive the effective Hamiltonian. A new type of quantum\npotential called SU(2) Zeeman interaction appears, which is induced by the\nelectric field and couples spin and intrinsic orbital angular momentum. Based\non the Hamiltonian, we discuss the spin precession for zero intrinsic orbital\nangular momentum case and the energy splitting caused by the SU(2) Zeeman\ninteraction for a helix as examples, showing the combined effect of geometry\nand external field. The new interaction may bring new approaches to manipulate\nquantum states in spintronics."
    },
    {
        "anchor": "Quantum Engineering of Spin and Anisotropy in Magnetic Molecular\n  Junctions: Single molecule magnets and single spin centers can be individually addressed\nwhen coupled to contacts forming an electrical junction. In order to control\nand engineer the magnetism of quantum devices, it is necessary to quantify how\nthe structural and chemical environment of the junction affects the spin\ncenter. Metrics such as coordination number or symmetry provide a simple method\nto quantify the local environment, but neglect the many-body interactions of an\nimpurity spin when coupled to contacts. Here, we utilize a highly corrugated\nhexagonal boron nitride (h-BN) monolayer to mediate the coupling between a\ncobalt spin in CoHx (x=1,2) complexes and the metal contact. While the hydrogen\natoms control the total effective spin, the corrugation is found to smoothly\ntune the Kondo exchange interaction between the spin and the underlying metal.\nUsing scanning tunneling microscopy and spectroscopy together with numerical\nsimulations, we quantitatively demonstrate how the Kondo exchange interaction\nmimics chemical tailoring and changes the magnetic anisotropy.",
        "positive": "Near-field thermodynamics and nanoscale energy harvesting: We study the thermodynamics of near-field thermal radiation between two\nidentical polar media at different temperatures. As an application, we consider\nan idealized energy harvesting process from sources at near room temperature at\nthe nanoscale. We compute the maximum work flux that can be extracted from the\nradiation in the near-field regime and compare it with the corresponding\nmaximum work flux in the blackbody regime. This work flux is considerably\nhigher in the near-field regime. For materials that support surface phonon\npolaritons, explicit expressions for the work flux and an upper bound for the\nefficiency as functions of the surface wave frequency are obtained."
    },
    {
        "anchor": "Topological melting of the metastable skyrmion lattice in the chiral\n  magnet Co$_9$Zn$_9$Mn$_2$: In a $\\beta$-Mn-type chiral magnet Co$_9$Zn$_9$Mn$_2$, we demonstrate that\nthe magnetic field-driven collapse of a room temperature metastable topological\nskyrmion lattice passes through a regime described by a partial topological\ncharge inversion. Using Lorentz transmission electron microscopy, the\nmagnetization distribution was observed directly as the magnetic field was\nswept antiparallel to the original skyrmion core magnetization, i.e. negative\nmagnetic fields. Due to the topological stability of skyrmions, a direct\ntransition of the metastable skyrmion lattice to the equilibrium helical state\nis avoided for increasingly negative fields. Instead, the metastable skyrmion\nlattice gradually transforms into giant magnetic bubbles separated by $2\\pi$\ndomain walls. Eventually these large structures give way to form a\nnear-homogeneously magnetized medium that unexpectedly hosts a low density of\nisolated skyrmions with inverted core magnetization, and thus a total\ntopological charge of reduced size and opposite sign compared with the initial\nstate. A similar phenomenon has been observed previously in systems hosting\nordered lattices of magnetic bubbles stabilized by the dipolar interaction and\ncalled \"topological melting\". With support from numerical calculations, we\nargue that the observed regime of partial topological charge inversion has its\norigin in the topological protection of the starting metastable skyrmion state.",
        "positive": "Broadband Tunable THz Absorption with Singular Graphene Metasurfaces: By exploiting singular spatial modulations of the graphene conductivity, we\ndesign a broadband, tunable THz absorber whose efficiency approaches the\ntheoretical upper bound for a wide absorption band with a fractional bandwidth\nof 185\\%. Strong field enhancement is exhibited by the modes of this extended\nstructure, which is able to excite a wealth of high order surface plasmons,\nenabling deeply subwavelength focussing of incident THz radiation. Previous\nstudies have shown that the conductivity can be modulated at GHz frequencies,\nwhich might lead to the development of efficient high speed broadband switching\nby an atomically thin layer."
    },
    {
        "anchor": "Two-dimensional Graphene Superlattice Made with Partial Hydrogenation: Electronic properties of two-dimensional graphene superlattice made with\npartial hydrogenation were thoroughly studied via Density Functional Tight\nBinding approach (DFTB) which incorporates the tight-binding method into the\ndensity functional formalism. The two-dimensional (2-d) pattern of hydrogen\natoms on graphene was found to have great effects on electronic structures of\ngraphene superlattice. In particular, the edges of the 2-d pattern, armchair or\nzigzag, are essential for the energy band gap opening, and the energy band gap\nsensitively depends on the shape, size, and the 2-d periodicity of the pattern.\nBased on these findings, we suggested that the 2-d graphene superlattice may be\nused in fabricating quantum dots and 2-d heterojunctions on graphene without\nthe need for cutting or etching.",
        "positive": "Exchange bias in phase-segregated Nd2/3Ca1/3MnO3 as a function of\n  temperature and cooling magnetic fields: Exchange bias (EB) phenomena have been observed in Nd2/3Ca1/3MnO3 colossal\nmagnetoresistance perovskite below the Curie temperature $T_{C}$ = 70 K and\nattributed to an antiferromagnetic (AFM) - ferromagnetic (FM) spontaneous phase\nsegregated state of this compound. Field cooled magnetic hysteresis loops\nexhibit shifts toward negative direction of the magnetic field axis. The values\nof exchange field $H_{EB}$ and coercivity $H_{C}$ are found to be strongly\ndependent of temperature and strength of the cooling magnetic field $H_{cool}$.\nThese effects are attributed to evolution of the FM phase content and a size of\nFM clusters. A contribution to the total magnetization of the system due to the\nFM phase has been evaluated. The exchange bias effect decreases with increasing\ntemperature up to $T_{C}$ and vanishes above this temperature with\ndisappearance of FM phase. Relaxation of a non-equilibrium magnetic state of\nthe compound manifests itself through a training effect also observed while\nstudying EB in Nd2/3Ca1/3MnO3."
    },
    {
        "anchor": "Persistent spin current in mesoscopic ferrimagnetic spin ring: Using a semiclassical approach, we study the persistent magnetization current\nof a mesoscopic ferrimagnetic ring in a nonuniform magnetic field. At zero\ntemperature, there exists persistent spin current because of the quantum\nfluctuation of magnons, similar to the case of an antiferromagnetic spin ring.\nAt low temperature, the current shows activation behavior because of the\nfield-induced gap. At higher temperature, the magnitude of the spin current is\nproportional to temperature T, similar to the reported result of a\nferromagnetic spin ring.",
        "positive": "Statistics of excitons in quantum dots and the resulting microcavity\n  emission spectra: A theoretical investigation is presented of the statistics of excitons in\nquantum dots (QDs) of different sizes. A formalism is developed to build the\nexciton creation operator in a dot from the single exciton wavefunction and it\nis shown how this operator evolves from purely fermionic, in case of a small\nQD, to purely bosonic, in case of large QDs. Nonlinear optical emission spectra\nof semiconductor microcavities containing single QDs are found to exhibit a\npeculiar multiplet structure which reduces to Mollow triplet and Rabi doublet\nin fermionic and bosonic limits, respectively."
    },
    {
        "anchor": "Coherent control and decoherence of charge states in quantum dots: This Chapter contains a review of the recent results, both experimental and\ntheoretical, related to optical control of carriers confined in semiconductor\nquantum dots. The physics of Rabi oscillations of exciton and biexciton\noccupations, as well as time-domain interference experiments are discussed.\nNext, the impact of carrier--phonon interaction in a semiconductor structure is\ndescribed and modern methods of theoretical description of the carrier--phonon\nkinetics and of the resulting dephasing are presented.",
        "positive": "Observation of charge density wave transition in TaSe3 mesowires: The quasi-one-dimensional (quasi-1D) TaSe3 attracts considerable attention\nfor its intriguing superconductivity and possible interplay with nontrivial\ntopology and charge density wave (CDW) state. However, unlike the isostructural\nanalogues, CDW has not been observed for TaSe3 despite its quasi-1D character\nthat is supposed to promote Peierls instabilities and CDW. Here we synthesize\nTaSe3 mesowires (MWs) using a one-step approach. For the MW of ~300 nm thick, a\ndistinct CDW transition occurs at 65 K in the resistivity measurement, which\nhas not been reported before and is further evidenced by the Raman\ncharacterization and susceptibility measurement. For comparison, we have also\nprepared bulk single crystal TaSe3. Although no anomaly appears in the\nresistivity and magnetoresistance measurements, the carrier type detected by\nHall effect varies from n-type to p-type below 50 K, suggesting a\nreconstruction of Fermi surface that could be associated with CDW. The\nenhancement of CDW in the MWs is attributed to the reduced dimensionality.\nTaSe3 is demonstrated to be a promising platform to study the correlation and\ncompetition of CDW and superconductivity in the quasi-1D systems."
    },
    {
        "anchor": "Patterns of the Aharonov-Bohm oscillations in graphene nanorings: Using extensive tight-binding calculations, we investigate (including the\nspin) the Aharonov-Bohm (AB) effect in monolayer and bilayer trigonal and\nhexagonal graphene rings with zigzag boundary conditions. Unlike the previous\nliterature, we demonstrate the universality of integer (hc/e) and half-integer\n(hc/2e) values for the period of the AB oscillations as a function of the\nmagnetic flux, in consonance with the case of mesoscopic metal rings. Odd-even\n(in the number of Dirac electrons, N) sawtooth-type patterns relating to the\nhalving of the period have also been found; they are more numerous for a\nmonolayer hexagonal ring, compared to the cases of a trigonal and a bilayer\nhexagonal ring. Additional more complicated patterns are also present,\ndepending on the shape of the graphene ring. Overall, the AB patterns repeat\nthemselves as a function of N with periods proportional to the number of the\nsides of the rings.",
        "positive": "Spin Seebeck effect and magnon diffusion length in\n  $\\rm{\\mathbf{Fe}}_{\\mathbf{3}}\\rm{\\mathbf{O}}_{\\mathbf{4}}$: The determination of the magnon diffusion length (MDL) is important for\nincreasing the efficiency of spin Seebeck effect (SSE) based devices utilising\nnon-metallic magnets. We extract the MDL at $50$ and $300\\,\\rm{K}$ in an\n$\\rm{Fe}_{3}\\rm{O}_{4}$ single crystal from the magnon dispersion obtained\nusing inelastic neutron scattering (INS) and find them to be equal within\nerror. We then measure the heat flux normalised SSE responses and in-plane\nmagnetization of $\\rm{Fe}_{3}\\rm{O}_{4}$ thin films and normalise by the static\nmagnetization contribution to the SSE before determining the MDLs from a fit of\nthe thickness dependence. We find that the MDLs determined in this way are\nsmaller than that measured from INS which maybe due to differences in magnon\npropagation between bulk and thin film $\\rm{Fe}_{3}\\rm{O}_{4}$."
    },
    {
        "anchor": "Band structures of bilayer graphene superlattices: We formulate a low energy effective Hamiltonian to study superlattices in\nbilayer graphene (BLG) using a minimal model which supports quadratic band\ntouching points. We show that a one dimensional (1D) periodic modulation of the\nchemical potential or the electric field perpendicular to the layers leads to\nthe generation of zero energy anisotropic massless Dirac fermions and finite\nenergy Dirac points with tunable velocities. The electric field superlattice\nmaps onto a coupled chain model comprised of 'topological' edge modes. 2D\nsuperlattice modulations are shown to lead to gaps on the mini-Brillouin zone\nboundary but do not, for certain symmetries, gap out the quadratic band\ntouching point. Such potential variations, induced by impurities and rippling\nin biased BLG, could lead to subgap modes which are argued to be relevant to\nunderstanding transport measurements.",
        "positive": "Coherent transmission through a one dimensional lattice: Based on the Keldysh nonequilibrium Green function (NGF) technique, a general\nformula for the current and transmission coefficient through a one dimensional\nlattice is derived without the consideration of electron-electron interactions.\n  We obtain an analytical condition for perfect resonant transmission when the\nlevels of sites are aligned, which depends on the parity of the number of\nsites. Localization-delocalization transition in a generic one dimensional\ndisordered lattice is also analyzed, depending on the correlation among the\nhopping parameters and the strength of the coupling to reservoirs. The\ndependence of the number and lineshape of resonant transmission and linear\nconductance peaks on the structure parameters of the lattice is also given in\nseveral site cases."
    },
    {
        "anchor": "Giant Resistance Switch in Twisted Transition Metal Dichalcogenide\n  Tunnel Junctions: Resistance switching in multilayer structures are typically based on\nmaterials possessing ferroic orders. Here we predict an extremely large\nresistance switching based on the relative spin-orbit splitting in twisted\ntransition metal dichalcogenide (TMD) monolayers tunnel junctions. Because of\nthe valence band spin splitting which depends on the valley index in the\nBrillouin zone, the perpendicular electronic transport through the junction\ndepends on the relative reciprocal space overlap of the spin-dependent Fermi\nsurfaces of both layers, which can be tuned by twisting one layer. Our quantum\ntransport calculations reveal a switching resistance of up to $10^6 \\%$ when\nthe relative alignment of TMDs goes from $0^{\\circ}$ to $60^{\\circ}$ and when\nthe angle is kept fixed at $60^{\\circ}$ and the Fermi level is varied. By\ncreating vacancies, we evaluate how inter-valley scattering affects the\nefficiency and find that the resistance switching remains large ($10^4 \\%$) for\ntypical values of vacancy concentration. Not only this resistance switching\nshould be observed at room temperature due to the large spin splitting, but our\nresults show how twist angle engineering and control of van der Waals\nheterostructures could be used for next-generation memory and electronic\napplications.",
        "positive": "Directional bonding explains high conductance values of atomic contacts\n  in bcc metals: Atomic-sized junctions of iron, created by controlled rupture, present\nunusually high values of conductance compared to other metals. This result is\ncounter-intuitive since, at the nanoscale, body-centered cubic metals are\nexpected to exhibit lower coordination than face-centered cubic metals. In this\nwork, classical molecular dynamics simulations of contact rupture, using an\ninteratomic potential that accounts for directional bonding, yield\nhighly-coordinated stable structures before rupture, unlike an isotropic\nbonding potential, which results in the expected stable single-atom contacts.\nDensity functional theory electronic transport calculations show that\nconductance values of these highly coordinated and highly stable structures,\ncan explain the experimentally measured values for conductance of body-centered\ncubic atomic contacts, thus revealing the important role of directional bonding\nin these metals."
    },
    {
        "anchor": "Energy transport and coherence properties of acoustic phonons generated\n  by optical excitation of a quantum dot: The energy transport of acoustic phonons generated by the optical excitation\nof a quantum dot as well as the coherence properties of these phonons are\nstudied theoretically both for the case of a pulsed excitation and for a\ncontinuous wave (cw) excitation switched on instantaneously. For a pulsed\nexcitation, depending on pulse area and pulse duration, a finite number of\nphonon wave packets is emitted, while for the case of a cw excitation a\nsequence of wave packets with decreasing amplitude is generated after the\nexcitation has been switched on. We show that the energy flow associated with\nthe generated phonons is partly related to coherent phonon oscillations and\npartly to incoherent phonon emission. The efficiency of the energy transfer to\nthe phonons and the details of the energy flow depend strongly and in a\nnon-monotonic way on the Rabi frequency exhibiting a resonance behavior.\nHowever, in the case of cw excitation it turns out that the total energy\ntransferred to the phonons is directly linked in a monotonic way to the Rabi\nfrequency.",
        "positive": "Exploring terahertz-scale exchange resonances in synthetic ferrimagnets\n  with ultrashort optically induced spin currents: Using spin currents generated by fs laser pulses, we demonstrate excitation\nof GHz ferromagnetic resonance and THz ferrimagnetic exchange resonances in\nCo/Gd/Co/Gd multilayers by time-resolved magneto-optic Kerr effect\nmeasurements. Varying the Gd layer thickness allows for a tuning of the\nresonance spectrum by manipulating the total angular momentum and strength of\neffective exchange fields between the antiferromagnetically coupled layers.\nClose to the compensation point of angular momentum, a minimum in the frequency\nof the exchange-dominated mode and a maximum in the frequency of the\nferromagnetic resonance mode is observed. Finally, to gain better understanding\nof the excitation mechanism, we analyze the anomalous variation in the measured\nexchange mode amplitude as a function of its frequency. A peak in this\namplitude in the vicinity of the compensation point of angular momentum is\nexplained using a macrospin model, taking nonlinear effects at finite\nprecession amplitudes into account."
    },
    {
        "anchor": "1D-1D Coulomb Drag Signature of a Luttinger Liquid: We report Coulomb drag measurements between vertically-integrated quantum\nwires separated by a barrier only 15 nm wide. The temperature dependence of the\ndrag resistance is measured in the true one-dimensional (1D) regime where both\nwires have less than one 1D subband occupied. As a function of temperature, an\nupturn in the drag resistance is observed in three distinct devices at a\ntemperature $T^* \\sim 1.6$ K. This crossover in Coulomb drag behaviour is\nconsistent with Tomonaga-Luttinger liquid models for the 1D-1D drag between\nquantum wires.",
        "positive": "Surface ferromagnetism in rhombohedral heptalayer graphene moire\n  superlattice: The topological electronic structure of crystalline materials often gives\nrise to intriguing surface states, such as Dirac surface states in topological\ninsulators, Fermi arc surface states in Dirac semimetals, and topological\nsuperconductivity in iron-based superconductors. Recently, rhombohedral\nmultilayer graphene has emerged as a promising platform for exploring exotic\nsurface states due to its hosting of topologically protected surface flat bands\nat low energy, with the layer-dependent energy dispersion. These flat bands can\npromote electron correlations, leading to a plethora of quantum phenomena,\nincluding spontaneous symmetry breaking, superconductivity, ferromagnetism, and\ntopological Chern insulators. Nevertheless, the intricate connection between\nthe surface flat bands in rhombohedral multilayer graphene and the highly\ndispersive high-energy bands hinders the exploration of correlated surface\nstates. Here, we present a method to isolate the surface flat bands of\nrhombohedral heptalayer (7L) graphene by introducing moire superlattices. The\npronounced screening effects observed in the moire potential-modulated\nrhombohedral 7L graphene indicate its essential three-dimensional (3D) nature.\nThe isolated surface flat bands favor correlated states on the surface in the\nregions away from charge-neutrality points. Most notably, we observe tunable\nsurface ferromagnetism, manifested as an anomalous Hall effect with hysteresis\nloops, which is achieved by polarizing surface states using finite displacement\nfields. Our work establishes rhombohedral multilayer graphene moire\nsuperlattice as a unique 3D system for exploring correlated surface states."
    },
    {
        "anchor": "Resonant nature of phonon-induced damping of Rabi oscillations in\n  quantum dots: Optically controlled coherent dynamics of charge (excitonic) degrees of\nfreedom in a semiconductor quantum dot under the influence of lattice dynamics\n(phonons) is discussed theoretically. We show that the dynamics of the lattice\nresponse in the strongly non-linear regime is governed by a semiclassical\nresonance between the phonon modes and the optically driven dynamics. We stress\non the importance of the stability of intermediate states for the truly\ncoherent control.",
        "positive": "Thermal Conductance of a Single-Electron Transistor: We report on combined measurements of heat and charge transport through a\nsingle-electron transistor. The device acts as a heat switch actuated by the\nvoltage applied on the gate. The Wiedemann-Franz law for the ratio of heat and\ncharge conductances is found to be systematically violated away from the charge\ndegeneracy points. The observed deviation agrees well with the theoretical\nexpectation. With large temperature drop between the source and drain, the heat\ncurrent away from degeneracy deviates from the standard quadratic dependence in\nthe two temperatures."
    },
    {
        "anchor": "Deformation Effect on Graphene Quantum Dot/Graphane and Silicene Quantum\n  Dot/Silicane array: This article presents a design for the two-dimensional heterostructure (2DH)\nsystems of graphane quantum dot array in graphane (GQD/Graphane), and silicene\nquantum dot array in silicane (SiQD/Silicane). A first-principles method was\nused to evaluate the deformation effect for magnetism as well as the electronic\nproperties for the 2DH systems. The energy levels of quantum dot (QD) array and\nthe band structure of its hydrogenated counterpart are coupling for both 2DH\nsystems of C and Si. The hydrogenated part shares part of strain on QD array,\nhowever, the strain sharing effect is stronger in SiQD/silicane than in\nGQD/graphane. The strain sharing enhances the band coupling of the QD and its\nhydrogen counterpart in the low energy region. The band coupling alters the\nelectronic properties of the 2DH systems and change the magnetic properties of\ntriangular and parallelogram of SiQD/Silicane array under compressive strain\nlarger than 5%. Strain modulates the band gap of the 2DH system. For\nSiQD/Silicane systems, the homogeneous strain not only induces the phase\ntransition of from semiconductor to metal, but also remove the magnetism of\ntriangular and parallelogram SiQD array. The 2DH system can be used in the\ndesign of nanoelectronic devices and binary logic based on nanoscale magnetism.",
        "positive": "Spin transistor action from Onsager reciprocity and SU(2) gauge theory: We construct a local gauge transformation to show how, in confined systems, a\ngeneric, weak nonhomogeneous SU(2) spin-orbit Hamiltonian reduces to two U(1)\nHamiltonians for spinless fermions at opposite magnetic fields, to leading\norder in the spin-orbit strength. Using an Onsager relation, we further show\nhow the resulting spin conductance vanishes in a two-terminal setup, and how it\nis turned on by either weakly breaking time-reversal symmetry or opening\nadditional transport terminals. We numerically check our theory for mesoscopic\ncavities as well as Aharonov-Bohm rings."
    },
    {
        "anchor": "Bound states and local topological phase diagram of classical impurity\n  spins coupled to a Chern insulator: The existence of bound states induced by local impurities coupled to an\ninsulating host depends decisively on the global topological properties of the\nhost's electronic structure. In this context, we consider magnetic impurities\nmodelled as classical unit-length spins that are exchange-coupled to the\nspinful Haldane model on the honeycomb lattice. We investigate the spectral\nflow of bound states with the coupling strength $J$ in both the topologically\ntrivial and Chern-insulating phases. In addition to conventional $k$-space\ntopology, an additional, spatially local topological feature is available,\nbased on the space of impurity-spin configurations forming, in case of $R$\nimpurities, an $R$-fold direct product of two-dimensional spheres. Global\n$k$-space and local $S$-space topology are represented by different topological\ninvariants, the first ($k$-space) Chern number and the $R$-th ($S$-space)\nspin-Chern number. We demonstrate that there is a local $S$-space topological\ntransition as a function of $J$ associated with a change in the spin Chern\nnumber and work out the implications of this for the $J$-dependent local\nelectronic structure close to the impurities and, in particular, for in-gap\nbound states. The critical exchange couplings' dependence on the parameters of\nthe Haldane model, and thus on the $k$-space topological state, is obtained\nnumerically to construct local topological phase diagrams for systems with\n$R=1$ and $R=2$ impurity spins.",
        "positive": "Coherent dynamics in long fluxonium qubits: We analyze the coherent dynamics of a fluxonium device (Manucharyan et al\n2009 Science 326 113) formed by a superconducting ring of Josephson junctions\nin which strong quantum phase fluctuations are localized exclusively on a\nsingle weak element. In such a system, quantum phase tunnelling by $2\\pi $\noccurring at the weak element couples the states of the ring with supercurrents\ncirculating in opposite directions, while the rest of the ring provides an\nintrinsic electromagnetic environment of the qubit. Taking into account the\ncapacitive coupling between nearest neighbors and the capacitance to the\nground, we show that the homogeneous part of the ring can sustain\nelectrodynamic modes which couple to the two levels of the flux qubit. In\nparticular, when the number of Josephson junctions is increased, several\nlow-energy modes can have frequencies lower than the qubit frequency. This\ngives rise to a quasiperiodic dynamics, which manifests itself as a decay of\noscillations between the two counterpropagating current states at short times,\nfollowed by oscillation-like revivals at later times. We analyze how the system\napproaches such a dynamics as the ring's length is increased and discuss\npossible experimental implications of this non-adiabatic regime."
    },
    {
        "anchor": "Formation of moir\u00e9 interlayer excitons in space and time: Moir\\'e superlattices in atomically thin van-der-Waals heterostructures hold\ngreat promise for an extended control of electronic and valleytronic lifetimes,\nthe confinement of excitons in artificial moir\\'e lattices, and the formation\nof novel exotic quantum phases. Such moir\\'e-induced emergent phenomena are\nparticularly strong for interlayer excitons, where the hole and the electron\nare localized in different layers of the heterostructure. In order to exploit\nthe full potential of correlated moir\\'e and exciton physics, a thorough\nunderstanding of the ultrafast interlayer exciton formation process and the\nreal-space wavefunction confinement in the moir\\'e potential is indispensable.\nHowever, direct experimental access to these parameters is limited since most\nexcitonic quasiparticles are optically dark. Here we show that femtosecond\nphotoemission momentum microscopy provides quantitative access to these key\nproperties of the moir\\'e interlayer excitons. We find that interlayer excitons\nare dominantly formed on the sub-50~fs timescale via interlayer tunneling at\nthe K valleys of the Brillouin zones. In addition, we directly measure\nenergy-momentum fingerprints of the moir\\'e interlayer excitons by mapping\ntheir spectral signatures within the mini Brillouin zone that is built up by\nthe twisted heterostructure. From these momentum-fingerprints, we gain\nquantitative access to the modulation of the exciton wavefunction within the\nmoir\\'e potential in real-space. Our work provides the first direct access to\nthe interlayer moir\\'e exciton formation dynamics in space and time and reveals\nnew opportunities to study correlated moir\\'e and exciton physics for the\nfuture realization of exotic quantum phases of matter.",
        "positive": "Metal-insulator transition in three dimensional Anderson model:\n  universal scaling of higher Lyapunov exponents: Numerical studies of the Anderson transition are based on the finite-size\nscaling analysis of the smallest positive Lyapunov exponent. We prove\nnumerically that the same scaling holds also for higher Lyapunov exponents.\nThis scaling supports the hypothesis of the one-parameter scaling of the\nconductance distribution. From the collected numerical data for quasi one\ndimensional systems up to the system size 24 x 24 x infinity we found the\ncritical disorder 16.50 < Wc < 16.53 and the critical exponent 1.50 < \\nu <\n1.54. Finite-size effects and the role of irrelevant scaling parameters are\ndiscussed."
    },
    {
        "anchor": "Scanning Tunneling Microscopy of Gate Tunable Topological Insulator\n  Bi2Se3 Thin Films: Electrical field control of the carrier density of topological insulators\n(TI) has greatly expanded the possible practical use of these materials.\nHowever, the combination of low temperature local probe studies and a gate\ntunable TI device remains challenging. We have overcome this limitation by\nscanning tunneling microscopy and spectroscopy measurements on in-situ\nmolecular beam epitaxy growth of Bi2Se3 films on SrTiO3 substrates with\npre-patterned electrodes. Using this gating method, we are able to shift the\nFermi level of the top surface states by 250 meV on a 3 nm thick Bi2Se3 device.\nWe report field effect studies of the surface state dispersion, band gap, and\nelectronic structure at the Fermi level.",
        "positive": "Large-signal model of 2DFETs: compact modeling of terminal charges and\n  intrinsic capacitances: We present a physics-based circuit-compatible model for double-gated\ntwo-dimensional semiconductor based field effect transistors, which provides\nexplicit expressions for the drain current, terminal charges and intrinsic\ncapacitances. The drain current model is based on the drift-diffusion mechanism\nfor the carrier transport and considers Fermi-Dirac statistics coupled with an\nappropriate field-effect approach. The terminal charge and intrinsic\ncapacitance models are calculated adopting a Ward-Dutton linear charge\npartition scheme that guarantees charge-conservation. It has been implemented\nin Verilog-A to make it compatible with standard circuit simulators. In order\nto benchmark the proposed modeling framework we also present experimental DC\nand high-frequency measurements of a purposely fabricated monolayer MoS2 FET\nshowing excellent agreement between the model and the experiment and thus\ndemonstrating the capabilities of the combined approach to predict the\nperformance of 2DFETs."
    },
    {
        "anchor": "$8\u03c0$-periodic dissipationless ac Josephson effect on a quantum\n  spin-Hall edge via a Quantum magnetic impurity: Time-reversal invariance places strong constraints on the properties of the\nquantum spin Hall edge. One such restriction is the inevitability of\ndissipation in a Josephson junction between two superconductors formed on such\nan edge without the presence of interaction. Interactions and spin-conservation\nbreaking are key ingredients for the realization of dissipationless ac\nJosephson effect on such quantum spin Hall edges. We present a simple quantum\nimpurity model that allows to create a dissipationless fractional Josephson\neffect on a quantum spin Hall edge. We then use this model to substantiate a\ngeneral argument that shows that any such non-dissipative Josephson effect must\nnecessarily by $8\\pi$-periodic.",
        "positive": "Topological phase and edge states dependence of the RKKY interaction in\n  zigzag silicene nanoribbon: We propose versatile materials based on the Ruderman-Kittel-Kasuya-Yosida\n(RKKY) interaction in a zigzag silicene nanoribbon (ZSNR) on half filling in\nthe presence of an out-of-plane electric field. We show that the topological\nphase transition in the band dispersion of ZSNR can be probed by using the RKKY\ninteraction. We find that, due to the zero-energy edge states of the ZSNR, the\nexchange coupling is significantly enhanced when the impurities are located on\nthe zigzag edges, and also explore that the strength of the interaction in the\ntopological insulator phase is much greater than that when the system is in the\nband insulator region. We present a model to investigate the phase of a system\nof two magnetic impurities located on the edge of the ZSNR and find that three\ndifferent magnetic phases, spiral, ferromagnetic, and anti-ferromagnetic, are\npossible for different values of the electric field. This electrical tunability\nof the magnetic phases in silicene can be explored by using current\nexperimental techniques and can be of interest in the field of spintronics."
    },
    {
        "anchor": "Surface-response functions obtained from equilibrium electron-density\n  profiles: Surface-response functions are one of the most promising routes for bridging\nthe gap between fully quantum-mechanical calculations and phenomenological\nmodels in quantum nanoplasmonics. Within all the currently available recipes\nfor obtaining such response functions, \\emph{ab initio} calculations remain one\nof the most predominant, wherein the surface-response function are retrieved\nvia the metal's non-equilibrium response to an external perturbation. Here, we\npresent a complementary approach where one of the most appealing\nsurface-response functions, namely the Feibelman $d$-parameters, yield a finite\ncontribution even in the case where they are calculated directly from the\nequilibrium properties described under the local-response approximation (LRA),\nbut with a spatially varying equilibrium electron density. Using model\ncalculations that mimic both spill-in and spill-out of the equilibrium electron\ndensity, we show that the obtained $d$-parameters are in qualitative agreement\nwith more elaborate, but also more computationally demanding, \\emph{ab initio}\nmethods. The analytical work presented here illustrates how microscopic\nsurface-response functions can emerge out of entirely local electrodynamic\nconsiderations.",
        "positive": "Spin-hedgehog-derived electromagnetic effects in itinerant magnets: In itinerant magnets, the indirect exchange coupling of\nRuderman-Kittel-Kasuya-Yosida type is known to stabilize incommensurate spin\nspiral. Whereas an account of higher order spin interactions favors the\nformation of a noncoplanar magnetic texture. This is manifested by the finite\nBerry phase the conduction electrons accumulate when their spins follow this\ntexture, leading thus to the topological Hall effect. We herein utilize the\neffective spin model with bilinear-biquadratic exchange interactions for\nstudying the formation of the magnetic hedgehog lattice, that represents a\nperiodic array of magnetic anti- and monopoles and has been recently observed\nin the B20-type compounds, in a three-dimensional itinerant magnet. As opposed\nto widely used Monte Carlo simulations, we employ a neural-network-based\napproach for exploring the ground state spin configuration in a\nnoncentrosymmetric crystal structure. Further, we address the topological Hall\nconductivity, associated with nonzero scalar spin chirality, in the itinerant\nmagnet due to the coupling to the spin hedgehog lattice, and provide the\nevidence of magneto-optic Kerr effect."
    },
    {
        "anchor": "Deep subwavelength thermal switch via resonant coupling in monolayer\n  hexagonal boron nitride: Unlike the electrical conductance that can be widely modulated within the\nsame material even in deep nanoscale devices, tuning the thermal conductance\nwithin a single material system or nanostructure is extremely challenging and\nrequires a large-scale device. This prohibits the realization of robust ON/OFF\nstates in switching the flow of thermal currents. Here, we present the theory\nof a thermal switch based on resonant coupling of three photonic resonators, in\nanalogy to the field-effect electronic transistor composed of a source, gate,\nand drain. As a material platform, we capitalize on the extreme tunability and\nlow-loss resonances observed in the dielectric function of monolayer hexagonal\nboron nitride (hBN) under controlled strain. We derive the dielectric function\nof hBN from first principles, including the phonon-polariton linewidths\ncomputed by considering phonon isotope and anharmonic phonon-phonon scattering.\nSubsequently, we propose a strain-controlled hBN-based thermal switch that\nmodulates thermal conductance by more than an order of magnitude, corresponding\nto an ON/OFF contrast ratio of 98%, in a deep subwavelength nanostructure.",
        "positive": "Electronic and Magnetic Properties of Small Fullerene Carbon Nanobuds: A\n  DFT Study: The electronic and magnetic properties of carbon nanobuds have been\ninvestigated using density functional theory. The carbon nanobuds are formed by\nattaching smaller fullerenes (C20, C28, C36 and C40) of variable size with\n(5,5) ACNT and (5,0) ZCNT. Fullerenes interact strongly with CNT surface having\nbinding energies within the range -0.93eV to -4.06eV. The C-C bond lengths near\nthe attachment region increase from the original C-C bond lengths. The relative\nstabilities of the nanobuds are closely related to C-C bond lengths and bond\nangles in cycloaddition reaction. Nanobuds formed by bond cycloaddition are\nenergetically most favorable amongst all cycloadditions. The electronic and\nmagnetic properties of nanobuds depend strongly on electronic properties of its\nbuilding blocks. The attachment of C20 and C40 on CNTs open up the HOMO-LUMO\ngaps of nanobuds whereas C28 and C36 results in addition of impurity states\nnear the Fermi level. The total magnetic moment of nanobuds vary from\n0.28{\\mu}B to 4.00{\\mu}B which depend on the nature of bonding between\nfullerene and CNTs. The results outline the potential of nanobuds as hybrid\ncarbon nanostructures and how their properties can be tuned with the size and\ntype of fullerene attached."
    },
    {
        "anchor": "Efficient Magnon Injection and Detection via the Orbital Rashba\n  Edelstein Effect: Orbital currents and accumulation provide a new avenue to boost spintronic\neffects in nanodevices. Here we use interconversion effects between charge\ncurrent and orbital angular momentum to demonstrate a dramatic increase in the\nmagnon spin injection and detection efficiencies in nanodevices consisting of a\nmagnetic insulator contacted by Pt/CuOx electrodes. Moreover, we note distinct\nvariations in efficiency for magnon spin injection and detection, indicating a\ndisparity in the direct and inverse orbital Rashba Edelstein effect\nefficiencies.",
        "positive": "Multi-channel Kondo impurity dynamics in a Majorana device: We study the multi-channel Kondo impurity dynamics realized in a mesoscopic\nsuperconducting island connected to metallic leads. The effective 'impurity\nspin' is non-locally realized by Majorana bound states and strongly coupled to\nlead electrons by non-Fermi liquid correlations. We explore the spin dynamics\nand its observable ramifications near the low-temperature fixed point. The\ntopological protection of the system raises the perspective to observe\nmulti-channel Kondo impurity dynamics in experimentally realistic environments."
    },
    {
        "anchor": "Spin dynamics of current driven single magnetic adatoms and molecules: A scanning tunneling microscope can probe the inelastic spin excitations of a\nsingle magnetic atom in a surface via spin-flip assisted tunneling in which\ntransport electrons exchange spin and energy with the atomic spin. If the\ninelastic transport time, defined as the average time elapsed between two\ninelastic spin flip events, is shorter than the atom spin relaxation time, the\nSTM current can drive the spin out of equilibrium. Here we model this process\nusing rate equations and a model Hamiltonian that describes successfully spin\nflip assisted tunneling experiments, including a single Mn atom, a Mn dimer and\nFe Phthalocyanine molecules. When the STM current is not spin polarized, the\nnon-equilibrium spin dynamics of the magnetic atom results in non-monotonic\n$dI/dV$ curves. In the case of spin polarized STM current, the spin orientation\nof the magnetic atom can be controlled parallel or anti-parallel to the\nmagnetic moment of the tip. Thus, spin polarized STM tips can be used both to\nprobe and to control the magnetic moment of a single atom.",
        "positive": "Quantum-mechanical wavepacket transport in quantum cascade laser\n  structures: We present a viewpoint of the transport process in quantum cascade laser\nstructures in which spatial transport of charge through the structure is a\nproperty of coherent quantum-mechanical wavefunctions. In contrast, scattering\nprocesses redistribute particles in energy and momentum but do not directly\ncause spatial motion of charge."
    },
    {
        "anchor": "Relativistic Gurzhi effect in channels of Dirac materials: Charge transport in channel-shaped 2D Dirac systems is studied employing the\nBoltzmann equation. The dependence of the resistivity on temperature and\nchemical potential is investigated. An accurate understanding of the influence\nof electron-electron interaction and material disorder allows us to identify a\nparameter regime, where the system reveals hydrodynamic transport behavior. We\npoint out the conditions for three Dirac fermion specific features: heat flow\nhydrodynamics, pseudo\\-diffusive transport, and the electron-hole scattering\ndominated regime. It is demonstrated that for clean samples the relativistic\nGurzhi effect, a definite indicator of hydrodynamic transport, can be observed.",
        "positive": "Tuning the thermal conductance of molecular junctions with interference\n  effects: We present an \\emph{ab initio} study of the role of interference effects in\nthe thermal conductance of single-molecule junctions. To be precise, using a\nfirst-principles transport method based on density functional theory, we\nanalyze the coherent phonon transport in single-molecule junctions based on\nseveral benzene and oligo-phenylene-ethynylene derivatives. We show that the\nthermal conductance of these junctions can be tuned via the inclusion of\nsubstituents, which induces destructive interference effects and results in a\ndecrease of the thermal conductance with respect to the unmodified molecules.\nIn particular, we demonstrate that these interference effects manifest as\nantiresonances in the phonon transmission, whose energy positions can be\ncontrolled by varying the mass of the substituents. Our work provides clear\nstrategies for the heat management in molecular junctions and more generally in\nnanostructured metal-organic hybrid systems, which are important to determine,\nhow these systems can function as efficient energy-conversion devices such as\nthermoelectric generators and refrigerators."
    },
    {
        "anchor": "Odd-even rule for zero-bias tunneling conductance in coupled Majorana\n  wire arrays: A semiconducting nanowire with strong Rashba coupling and in proximity of a\nsuperconductor hosts Majorana edge modes. An array of such nanowires with\ninter-wire coupling gives an approximate description of a two-dimensional\ntopological superconductor, where depending on the strength of the magnetic\nfield and the chemical potential, a rich phase diagram hosting trivial and\ndifferent types of non-trivial phases can be achieved. Here, we theoretically\nconsider such a two-dimensional assembly of spin-orbit coupled superconducting\nnanowires and calculate the collective tunneling conductance between normal\nelectrodes and the wires in the topological regime. When the number of wires in\nthe assembly is $N$, as a consequence of the way the Majorana bonding and\nanti-bonding states form, we find that $N$ conductance peaks symmetric about\nthe bias $V = 0$ appear, for even $N$. When $N$ is odd, a ZBCP also appears.\nSuch an assembly can be realized by standard nano-fabrication techniques where\nindividual nanowires can be turned $ON$ or $OFF$ by using mechanical switch (or\nlocal top gating) to make $N$ either even or odd -- thereby switching the ZBCP\n$OFF$ or $ON$, respectively. Hence, our results can be used to realize and\ndetect topological superconductivity efficiently, unambiguously and in a\ncontrolled manner.",
        "positive": "Role of Metal Nanoparticles on porosification of silicon by metal\n  induced etching (MIE): Porosification of silicon (Si) by metal induced etching (MIE) process have\nbeen studies here to understand the etching mechanism. The etching mechanism\nhas been discussed on the basis of electron transfer from Si to metal ion\n(Ag$^+$) and metal to H$_2$O$_2$. Role of silver nanoparticles (AgNPs) in the\netching process has been investigated by studying the effect of AgNPs coverage\non surface porosity. A quantitative analysis of SEM images, done using Image J,\nshows a direct correlation between AgNPs coverage and surface porosity after\nthe porosification. Density of Si nanowires (NWs) also varies as a function of\nAgNPs fractional coverage which reasserts the fact that AgNPs governs the\nporosification process during MIE."
    },
    {
        "anchor": "Nanoscopic Tunneling Contacts on Mesoscopic Multiprobe Conductors: We derive Bardeen-like expressions for the transmission probabilities between\ntwo multi-probe mesoscopic conductors coupled by a weak tunneling contact. We\nemphasize especially the dual role of a weak coupling contact as a current\nsource and sink and analyze the magnetic field symmetry. In the limit of a\npoint-like tunneling contact the transmission probability becomes a product of\nlocal, partial density of states of the two mesoscopic conductors. We present\nexpressions for the partial density of states in terms of functional\nderivatives of the scattering matrix with respect to the local potential and in\nterms of wave functions. We discuss voltage measurements and resistance\nmeasurements in the transport state of conductors. We illustrate the theory for\nthe simple case of a scatterer in an otherwise perfect wire. In particular, we\ninvestigate the development of the Hall-resistance as measured with weak\ncoupling probes.",
        "positive": "Spin wave amplification driven by heat flow: the role of damping and\n  exchange interaction: In this article we report on micromagnetic simulations performed on a\npermalloy nanostructure in presence of a uniform thermal gradient. Our\nnumerical simulations show that heat flow is an effective mean to compensate\nthe damping, and that the gradients at which spin-wave amplification is\nobserved are experimentally accessible. In particular, we have studied the role\nof the Gilbert damping parameter on spin-wave amplification."
    },
    {
        "anchor": "Atomistic Full-Band Simulations of Monolayer MoS2 Transistors: We study the transport properties of deeply scaled monolayer MoS2 n-channel\nmetal-oxide-semiconductor field effect transistors (MOSFETs) using full-band\nballistic quantum transport simulations with an atomistic tight-binding\nHamiltonian obtained from density functional theory. Our simulations suggest\nthat monolayer MoS2 MOSFETs can provide near-ideal subthreshold slope, and\nsuppression of drain-induced barrier lowering (DIBL) and gate-induced drain\nleakage (GIDL). However, these full-band simulations also exhibit limited\ntransconductance. These ballistic simulations also exhibit negative\ndifferential resistance (NDR) in the output characteristics associated with the\nnarrow width in energy of the lowest conduction band, but this NDR may be\nsubstantially reduced or eliminated by scattering in MoS2.",
        "positive": "Suris tetrons: possible spectroscopic evidence for four-particle optical\n  excitations of the 2D electron gas: The excitations of a two-dimensional electron gas in quantum wells with\nintermediate carrier density (~10^{11} cm^{-2}), i.e., between the\nexciton-trion- and the Fermi-Sea range, are so far poorly understood. We report\non an approach to bridge this gap by a magneto-photoluminescence study of\nmodulation-doped (Cd,Mn)Te quantum well structures. Employing their enhanced\nspin splitting, we analyzed the characteristic magnetic-field behavior of the\nindividual photoluminescence features. Based on these results and earlier\nfindings by other authors, we present a new approach for understanding the\noptical transitions at intermediate densities in terms of four-particle\nexcitations, the Suris tetrons, which were up to now only predicted\ntheoretically. All characteristic photoluminescence features are attributed to\nemission from these quasi-particles when attaining different final states."
    },
    {
        "anchor": "Large-Scale Atomistic Simulations of Environmental Effects on the\n  Formation and Properties of Molecular Junctions: Using an updated simulation tool, we examine molecular junctions comprised of\nbenzene-1,4-dithiolate bonded between gold nanotips, focusing on the importance\nof environmental factors and inter-electrode distance on the formation and\nstructure of bridged molecules. We investigate the complex relationship between\nmonolayer density and tip separation, finding that the formation of\nmulti-molecule junctions is favored at low monolayer density, while\nsingle-molecule junctions are favored at high density. We demonstrate that tip\ngeometry and monolayer interactions, two factors that are often neglected in\nsimulation, affect the bonding geometry and tilt angle of bridged molecules. We\nfurther show that the structures of bridged molecules at 298 and 77 K are\nsimilar.",
        "positive": "Hyperfine interaction induced critical exponents in the quantum Hall\n  effect: We study localization-delocalization transition in quantum Hall systems with\na random field of nuclear spins acting on two-dimensional (2d) electron spins\nvia hyperfine contact (Fermi) interaction. We use Chalker-Coddington network\nmodel, which corresponds to the projection onto the lowest Landau level. The\ninhomogeneous nuclear polarization acts on the electrons as an additional\nconfining potential, and, therefore, introduces additional parameter $p$ (the\nprobability to find a polarized nucleus in the vicinity of a saddle point of\nrandom potential) responsible for the change from quantum to classical\nbehavior. In this manner we obtain two critical exponents corresponding to\nquantum and classical percolation. We also study how the 2d extended state\ndevelops into the one-dimensional (1d) critical state."
    },
    {
        "anchor": "Magnetostatic interaction energy between a point magnet and a ring\n  magnet: We find an exact closed-form expression for the magnetostatic interaction\nenergy between a point magnet and a ring magnet in terms of complete elliptic\nintegrals. The exact expression for the energy exhibits an equilibrium point\nclose to the axis of symmetry of the ring magnet. Our methodology will be\nuseful in investigations concerning magnetic levitation, and in the study of\nCasimir levitation.",
        "positive": "Majorana zero modes choose Euler numbers - revealed by full counting\n  statistics: We study transport properties of a quantum dot coupled to a Majorana zero\nmode and two normal leads. We investigate the full counting statistics of\ncharge tunneling events which allows one to extract complete information about\ncurrent fluctuations. Using a Keldysh path-integral approach, we compute the\ncumulant generating function. We first consider a noninteracting spinless\nregime, and find that for the symmetric dot-lead couplings, the zero-frequency\ncumulants exhibit a universal pattern of Euler numbers, independent of the\nmicroscopic parameters. For a spinful case, the Coulomb interaction effects are\ndiscussed for both strong interaction (single-electron occupancy regime) and\nweak interactions (perturbative regime). Compared to the case without Majorana\ncoupling, we show that, while the tunneling conductance might exhibit zero-bias\nanomaly, the full counting statistics is qualitatively different in the\npresence of the Majorana coupling."
    },
    {
        "anchor": "Coherent transport of interacting electrons through a single scatterer: Using the self-consistent Hartree-Fock method, we calculate the persistent\ncurrent of weakly-interacting spinless electrons in a one-dimensional ring\ncontaining a single delta-barrier. We find that the persistent current decays\nwith the system length (L) asymptotically like $I \\propto L^{-1-\\alpha}$, where\n$\\alpha > 0$ is the power depending only on the electron-electron interaction.\nWe also simulate tunneling of the weakly-interacting one-dimensional electron\ngas through a single delta-barrier in a finite wire biased by contacts. We find\nthat the Landauer conductance decays with the system length asymptotically like\n$L^{-2\\alpha}$. The power laws $L^{-1-\\alpha}$ and $L^{-2\\alpha}$ have so far\nbeen observed only in correlated models. Their existence in the Hartree-Fock\nmodel is thus surprising.",
        "positive": "Chiral magnetic plasmons in anomalous relativistic matter: The chiral plasmon modes of relativistic matter in background magnetic and\nstrain-induced pseudomagnetic fields are studied in detail using the consistent\nchiral kinetic theory. The results reveal a number of anomalous features of\nthese chiral magnetic and pseudomagnetic plasmons that could be used to\nidentify them in experiment. In a system with nonzero electric (chiral)\nchemical potential, the background magnetic (pseudomagnetic) fields not only\nmodify the values of the plasmon frequencies in the long-wavelength limit, but\nalso affect the qualitative dependence on the wave vector. Similar\nmodifications can be also induced by the chiral shift parameter in Weyl\nmaterials. Interestingly, even in the absence of the chiral shift and external\nfields, the chiral chemical potential alone leads to a splitting of plasmon\nenergies at linear order in the wave vector."
    },
    {
        "anchor": "Mechanism of Fast Axially--Symmetric Reversal of Magnetic Vortex Core: The magnetic vortex core in a nanodot can be switched by an alternating\ntransversal magnetic field. We propose a simple collective coordinate model\nwhich describes comprehensive vortex core dynamics, including resonant\nbehavior, weakly nonlinear regimes, and reversal dynamics. A chaotic dynamics\nof the vortex polarity is predicted. All analytical results were confirmed by\nmicromagnetic simulations.",
        "positive": "Interference of heavy holes in an Aharonov-Bohm ring: We study the coherent transport of heavy holes through a one-dimensional ring\nin the presence of spin-orbit coupling. Spin-orbit interaction of holes, cubic\nin the in-plane components of momentum, gives rise to an angular momentum\ndependent spin texture of the eigenstates and influences transport. We analyze\nthe dependence of the resulting differential conductance of the ring on hole\npolarization of the leads and the signature of the textures in the\nAharonov-Bohm oscillations when the ring is in a perpendicular magnetic field.\nWe find that the polarization-resolved conductance reveals whether the dominant\nspin-orbit coupling is of Dresselhaus or Rashba type, and that the cubic\nspin-orbit coupling can be distinguished from the conventional linear coupling\nby observing the four-peak structure in the Aharonov-Bohm oscillations."
    },
    {
        "anchor": "Time-Resolved Imaging Reveals Transiently Chaotic\n  Spin-Orbit-Torque-Driven Dynamics Under Controlled Conditions: Spin-orbit torques (SOTs) act as efficient drivers for nanoscale magnetic\nsystems, such as in magnetic tunnel junctions, nano-oscillators and racetrack\ngeometries. In particular, in combination with materials exhibiting high\nDzyaloshinskii--Moriya interaction, SOTs are considered to result in\nwell-controlled deterministic magnetisation dynamics and are, therefore, used\nas robust drives to move and create magnetic skyrmions. In contrast to these\nexpectations, we here find unpredictable, transiently chaotic dynamics induced\nby SOT at an artificial anisotropy-engineered defect in a magnetic racetrack.\nBased on these controlled conditions, we directly observe the nanoscale\ndynamics with holography-based, time-resolved x-ray imaging. In concert with\nmicromagnetic simulations, we disclose a regime of violent picosecond\nfluctuations, including topological instabilities that, remarkably, result in\ndeterministic final configurations. In addition, our images expose previously\nunseen skyrmion shedding and highlight the potential of transiently chaotic\npathways for topological switching. Our approach offers new perspectives for\nthe investigation and application of highly non-linear SOT dynamics in\nspintronics materials.",
        "positive": "Two-Qubit Couplings of Singlet-Triplet Qubits Mediated by One Quantum\n  State: We describe high-fidelity entangling gates between singlet-triplet qubits\n(STQs) which are coupled via one quantum state (QS). The QS can be provided by\na quantum dot itself or by another confined system. The orbital energies of the\nQS are tunable using an electric gate close to the QS, which changes the\ninteractions between the STQs independent of their single-qubit parameters.\nShort gating sequences exist for the controlled NOT (CNOT) operations. We show\nthat realistic quantum dot setups permit excellent entangling operations with\ngate infidelities below $10^{-3}$, which is lower than the quantum error\ncorrection threshold of the surface code. We consider limitations from\nfabrication errors, hyperfine interactions, spin-orbit interactions, and charge\nnoise in GaAs and Si heterostructures."
    },
    {
        "anchor": "Mapping spin-polarised transitions with atomic resolution: The coupling between Angstrom-sized electron probes and spin polarised\nelectronic transitions shows that the inelastically scattered probe is in a\nmixed state containing electron vortices with non-zero orbital angular\nmomentum. These electrons create an asymmetric intensity distribution in energy\nfiltered diffraction patterns, giving access to maps of the magnetic moments\nwith atomic resolution. A feasibility experiment shows evidence of the\npredicted effect. Potential applications are column-by-column maps of magnetic\nordering, and the creation of Angstrom-sized free electrons with orbital\nangular momentum by inelastic scattering in a thin ferromagnetic foil.",
        "positive": "Landau-Level Mixing and SU(4) Symmetry Breaking in Graphene: Recent scanning tunneling microscopy experiments on graphene at charge\nneutrality under strong magnetic fields have uncovered a ground state\ncharacterized by Kekul\\'e distortion (KD). In contrast, non-local spin and\ncharge transport experiments in double-encapsulated graphene, which has a\nhigher dielectric constant, have identified an antiferromagnetic (AF) ground\nstate. We propose a mechanism to reconcile these conflicting observations, by\nshowing that Landau-level mixing can drive a transition from AF to KD with the\nreduction of the dielectric screening. Our conclusion is drawn from studying\nthe effect of Landau-level mixing on the lattice-scale, valley-dependent\ninteractions to leading order in graphene's fine structure constant $\\kappa =\ne^2/(\\hbar v_F \\epsilon)$. This analysis provides three key insights: 1)\nValley-dependent interactions remain predominantly short-range with the $m=0$\nHaldane pseudopotential being at least an order of magnitude greater than the\nothers, affirming the validity of delta-function approximation for these\ninteractions. 2) The phase transition between the AF and KD states is driven by\nthe microscopic process in the double-exchange Feynman diagram. 3) The\nmagnitudes of the coupling constants are significantly boosted by remote Landau\nlevels. Our model also provides a theoretical basis for numerical studies of\nfractional quantum Hall states in graphene."
    },
    {
        "anchor": "Superconducting proximity effect and zero-bias anomaly in transport\n  through quantum dots weakly attached to ferromagnetic leads: The Andreev transport through a quantum dot coupled to two external\nferromagnetic leads and one superconducting lead is studied theoretically by\nmeans of the real-time diagrammatic technique in the sequential and cotunneling\nregimes. We show that the tunnel magnetoresistance (TMR) of the Andreev current\ndisplays a nontrivial dependence on the bias voltage and the level detuning,\nand can be described by analytical formulas in the zero temperature limit. The\ncotunneling processes lead to a strong modification of the TMR, which is most\nvisible in the Coulomb blockade regime. We find a zero-bias anomaly of the\nAndreev differential conductance in the parallel configuration, which is\nassociated with a nonequilibrium spin accumulation in the dot triggered by\nAndreev processes.",
        "positive": "Electrically tunable transverse magnetic focusing in graphene: Electrons in a periodic lattice can propagate without scattering for\nmacroscopic distances despite the presence of the non-uniform Coulomb potential\ndue to the nuclei. Such ballistic motion of electrons allows the use of a\ntransverse magnetic field to focus electrons. This phenomenon, known as\ntransverse magnetic focusing (TMF), has been used to study the Fermi surface of\nmetals and semiconductor heterostructures, as well as to investigate Andreev\nreflection, spin-orbit interaction, and to detect composite fermions. Here we\nreport on the experimental observation of transverse magnetic focusing in high\nmobility mono-, bi-, and tri-layer graphene devices. The ability to tune the\ngraphene carrier density enables us for the first time to investigate TMF\ncontinuously from the hole to the electron regime and analyze the resulting\nfocusing fan. Moreover, by applying a transverse electric field to tri-layer\ngraphene, we use TMF as a ballistic electron spectroscopy method to investigate\ncontrolled changes in the electronic structure of a material. Finally, we\ndemonstrate that TMF survives in graphene up to 300 K, by far the highest\ntemperature reported for any system, opening the door to novel room temperature\napplications based on electron-optics."
    },
    {
        "anchor": "Acoustic topological circuitry in square and rectangular phononic\n  crystals: We systematically engineer a series of square and rectangular phononic\ncrystals to create experimental realisations of complex topological phononic\ncircuits. The exotic topological transport observed is wholly reliant upon the\nunderlying structure which must belong to either a square or rectangular\nlattice system and not to any hexagonal-based structure. The phononic system\nchosen consists of a periodic array of square steel bars which partitions\nacoustic waves in water over a broadband range of frequencies (~0.5 MHz). An\nultrasonic transducer launches an acoustic pulse which propagates along a\ndomain wall, before encountering a nodal point, from which the acoustic signal\npartitions towards three exit ports. Numerical simulations are performed to\nclearly illustrate the highly resolved edge states as well as corroborate our\nexperimental findings. To achieve complete control over the flow of energy,\npower division and redirection devices are required. The tunability afforded by\nour designs, in conjunction with the topological robustness of the modes, will\nresult in their assimilation into acoustical devices.",
        "positive": "Fermi polaron-polaritons in charge-tunable atomically thin\n  semiconductors: The dynamics of a mobile quantum impurity in a degenerate Fermi system is a\nfundamental problem in many-body physics. The interest in this field has been\nrenewed due to recent ground-breaking experiments with ultra-cold Fermi gases.\nOptical creation of an exciton or a polariton in a two-dimensional electron\nsystem embedded in a microcavity constitutes a new frontier for this field due\nto an interplay between cavity-coupling favoring ultra-low mass polariton\nformation and exciton-electron interactions leading to polaron or trion\nformation. Here, we present cavity spectroscopy of gate-tunable monolayer\nMoSe$_2$ exhibiting strongly bound trion and polaron resonances, as well as\nnon-perturbative coupling to a single microcavity mode. As the electron density\nis increased, the oscillator strength determined from the polariton splitting\nis gradually transferred from the higher-energy repulsive-exciton-polaron\nresonance to the lower-energy attractive-polaron manifold. Simultaneous\nobservation of polariton formation in both attractive and repulsive branches\nindicate a new regime of polaron physics where the polariton impurity mass is\nmuch smaller than that of the electrons. Our findings shed new light on optical\nresponse of semiconductors in the presence of free carriers by identifying the\nFermi polaron nature of excitonic resonances and constitute a first step in\ninvestigation of a new class of degenerate Bose-Fermi mixtures."
    },
    {
        "anchor": "Nanosecond True Random Number Generation with Superparamagnetic Tunnel\n  Junctions -- Identification of Joule Heating and Spin-Transfer-Torque effects: This work investigates nanosecond superparamagnetic switching in 50 nm\ndiameter in-plane magnetized magnetic tunnel junctions (MTJs). Due to the small\nin-plane uniaxial anisotropy, dwell times below 10 ns and auto-correlation\ntimes down to 5 ns are measured for circular superparamagnetic tunnel junctions\n(SMTJs). SMTJs exhibit probabilistic switching of the magnetic free layer,\nwhich can be used for the generation of true random numbers. The quality of\nrandom bitstreams, generated by our SMTJ, is evaluated with a statistical test\nsuite (NIST STS, sp 800-22) and shows true randomness after three XOR\noperations of four random SMTJ bitstreams. A low footprint CMOS circuit is\nproposed for fast and energy-efficient random number generation. We demonstrate\nthat the probability of a 1 or 0 can be tuned by spin-transfer-torque (STT),\nwhile the average bit generation rate is mainly affected by the current density\nvia Joule heating. Although both effects are always present in MTJs, Joule\nheating most often is neglected. However, with a resistance area (RA) product\nof 15 $\\Omega \\mu$m$^2$ and current densities of the order of 1 MA/cm$^2$, an\nincreasing temperature at the tunneling site results in a significant increase\nin the switching rate. As Joule heating and STT scale differently with current\ndensity, device design can be optimized based on our findings.",
        "positive": "Epitaxial graphene quantum dots for high-performance THz bolometers: Light absorption in graphene causes a large change in electron temperature,\ndue to low electronic heat capacity and weak electron phonon coupling [1-3],\nmaking it very attractive as a hot-electron bolometer material. Unfortunately,\nthe weak variation of electrical resistance with temperature has substantially\nlimited the responsivity of graphene bolometers. Here we show that quantum dots\nof epitaxial graphene on SiC exhibit an extraordinarily high variation of\nresistance with temperature due to quantum confinement, higher than 430 Mohm/K\nat 2.5 K, leading to responsivities for absorbed THz power above 10^10 V/W.\nThis is five orders of magnitude higher than other types of graphene hot\nelectron bolometers. The high responsivity combined with an extremely low\nnoise-equivalent power, about 0.2 fW/Hz^0.5 at 2.5K, place the performance of\ngraphene quantum dot bolometers well above commercial cooled bolometers.\nAdditionally, these quantum dot bolometers have the potential for superior\nperformance for operation above 77K."
    },
    {
        "anchor": "Analytic Coulomb matrix elements in the lowest Landau level in disk\n  geometry: Using Darling's theorem on products of generalized hypergeometric series an\nanalytic expression is obtained for the Coulomb matrix elements in the lowest\nLandau level in the representation of angular momentum. The result is important\nin the studies of Fractional Quantum Hall effect (FQHE) in disk geometry.\nMatrix elements are expressed as simple finite sums of positive terms,\neliminating the need to approximate these quantities with slowly-convergent\nseries. As a by-product, an analytic representation for certain integals of\nproducts of Laguerre polynomials is obtained.",
        "positive": "Auger recombination in Dirac materials: A tangle of many-body effects: The peculiar electron dispersion in Dirac materials makes lowest-order Auger\nprocesses prohibited or marginally prohibited by energy and momentum\nconservation laws. Thus, Auger recombination (AR) in these materials is very\nsensitive to many-body effects. We incorporate them at the level of the $GW$\napproximation into the nonequilibrium Green's functions approach to AR and\nstudy the role of dynamic screening, spectrum broadening and renormalization in\nthe case of weakly pumped undoped graphene. We find that incorrect treatment of\nmany-body effects can lead to an order-of-magnitude error in the recombination\nrate. We show that the AR time weakly (sublinearly) depends on the background\ndielectric constant, which limits the possibility to control recombination by\nthe choice of substrate. However, the AR time can be considerably prolonged by\nplacing graphene under a metal gate or by introducing a bandgap. With carrier\ncooling taken into account, our results comply with experiments on photoexcited\ngraphene."
    },
    {
        "anchor": "Tunable thermal conductivity in defect engineered nanowires at low\n  temperatures: We measure the thermal conductivity ($\\kappa$) of individual InAs nanowires\n(NWs), and find that it is 3 orders of magnitude smaller than the bulk value in\nthe temperature range of 10 to 50 K. We argue that the low $\\kappa$ arises from\nthe strong localization of phonons in the random superlattice of twin-defects\noriented perpendicular to the axis of the NW. We observe significant electronic\ncontribution arising from the surface accumulation layer which gives rise to\ntunability of $\\kappa$ with the application of electrostatic gate and magnetic\nfield. Our devices and measurements of $\\kappa$ at different carrier\nconcentrations and magnetic field without introducing structural defects, offer\na means to study new aspects of nanoscale thermal transport.",
        "positive": "Microwave resonances of magnetic skyrmions in thin film multilayers: Non-collinear magnets exhibit a rich array of dynamic properties at microwave\nfrequencies. They can host nanometre-scale topological textures known as\nskyrmions, whose spin resonances are expected to be highly sensitive to their\nlocal magnetic environment. Here, we report a magnetic resonance study of an\n[Ir/Fe/Co/Pt] multilayer hosting N\\'eel skyrmions at room temperature.\nExperiments reveal two distinct resonances of the skyrmion phase during\nin-plane ac excitation, with frequencies between 6-12 GHz. Complementary\nmicromagnetic simulations indicate that the net magnetic dipole moment rotates\ncounterclockwise (CCW) during both resonances. The magnon probability\ndistribution for the lower-frequency resonance is localised within isolated\nskyrmions, unlike the higher-frequency mode which principally originates from\nareas between skyrmions. However, the properties of both modes depend\nsensitively on the out-of-plane dipolar coupling, which is controlled via the\nferromagnetic layer spacing in our heterostructures. The gyrations of stable\nisolated skyrmions reported in this room temperature study encourage the\ndevelopment of new material platforms and applications based on skyrmion\nresonances. Moreover, our material architecture enables the resonance spectra\nto be tuned, thus extending the functionality of such applications over a\nbroadband frequency range."
    },
    {
        "anchor": "The universality of electronic friction II: Equivalence of the\n  quantum-classical Liouville equation approach with von Oppen's nonequilibrium\n  Green's function methods out of equilibrium: In a recent publication [W. Dou, G. Miao, and J. E. Subotnik, Phys. Rev.\nLett. 119, 046001 (2017)], using the quantum-classical Liouville equation\n(QCLE), we derived a very general form for the electronic friction felt by a\nmolecule moving near one or many metal surfaces. Moreover, we have already\nproved the equivalence of the QCLE electronic friction with the\nHead-Gordon--Tully model as well as a generalized version of von Oppen's\nnonequilibrium Green's function (NEGF) method at equilibrium [W. Dou and J. E.\nSubotnik, Phys. Rev. B 96, 104305 (2017)]. In the present paper, we now further\nprove the equivalence between the QCLE friction and the NEGF friction for the\ncase of multiple metal surfaces and an out-of-equilibrium electronic current.\nThe present results conclude our recent claim that there is only one universal\nelectronic friction tensor arising from the Born-Oppenheimer approximation.",
        "positive": "Time-reversal-symmetric topological magnetoelectric effect in\n  three-dimensional topological insulators: One of the hallmarks of time-reversal-symmetric topological insulators in\nthree dimensions is the topological magnetoelectric effect (TME). So far, a\ntime-reversal breaking variant of this effect has attracted much attention, in\nthe sense that the induced electric charge changes sign when the direction of\nan externally applied magnetic field is reversed. Theoretically, this effect is\ndescribed by the so-called axion term. Here, we discuss a\ntime-reversal-symmetric TME, where the electric charge depends only on the\nmagnitude of the magnetic field but is independent of its sign. We obtain this\nnonperturbative result by a combination of analytic and numerical arguments,\nand suggest a mesoscopic setup to demonstrate it experimentally."
    },
    {
        "anchor": "Spin-dependent thermoelectric transport in HgTe/CdTe quantum wells: We analyze thermally induced spin and charge transport in HgTe/CdTe quantum\nwells on the basis of the numerical non-equilibrium Green's function technique\nin the linear response regime. In the topologically non-trivial regime, we find\na clear signature of the gap of the edge states due to their finite overlap\nfrom opposite sample boundaries -- both in the charge Seebeck and spin Nernst\nsignal. We are able to fully understand the physical origin of the\nthermoelectric transport signatures of edge and bulk states based on simple\nanalytical models. Interestingly, we derive that the spin Nernst signal is\nrelated to the spin Hall conductance by a Mott-like relation which is exact to\nall orders in the temperature difference between the warm and the cold\nreservoir.",
        "positive": "Tunneling through nanosystems: Combining broadening with many-particle\n  states: We suggest a new approach for transport through finite systems based on the\nLiouville equation. By working in a basis of many-particle states for the\nfinite system, Coulomb interactions are taken fully into account and correlated\ntransitions by up to two different contact states are included. This latter\nextends standard rate equation models by including level-broadening effects.\nThe main result of the paper is a general expression for the elements of the\ndensity matrix of the finite size system, which can be applied whenever the\neigenstates and the couplings to the leads are known. The approach works for\narbitrary bias and for temperatures above the Kondo temperature. We apply the\napproach to standard models and good agreement with other methods in their\nrespective regime of validity is found."
    },
    {
        "anchor": "Counting statistics for entangled electrons: The counting statistics (CS) for charges passing through a coherent conductor\nis the most general quantity that characterizes electronic transport. CS not\nonly depends on the transport properties of the conductor but also depends on\nthe correlations among particles which compose the incident beam. In this paper\nwe present general results for the CS of entangled electron pairs traversing a\nbeam splitter and we show that the probability that Q charges have passed is\nnot binomial, as in the uncorrelated case, but rather it is symmetric with\nrespect to the average transferred charge. We furthermore consider the joint\nprobability for transmitted charges of a given spin and we show that the\nsignature of entanglement distinctly appears in a correlation which is not\npresent for the non-entangled case.",
        "positive": "Ergodic Edge Modes in the 4D Quantum Hall Effect: The gapless modes on the edge of four-dimensional (4D) quantum Hall droplets\nare known to be anisotropic: they only propagate in one direction, foliating\nthe 3D boundary into independent 1D conduction channels. This foliation is\nextremely sensitive to the confining potential and generically yields chaotic\nflows. Here we study the quantum correlations and entanglement of such edge\nmodes in 4D droplets confined by harmonic traps, whose boundary is a squashed\nthree-sphere. Commensurable trapping frequencies lead to periodic trajectories\nof electronic guiding centers; the corresponding edge modes propagate\nindependently along $S^1$ fibers, forming a bundle of 1D conformal field\ntheories over a 2D base space. By contrast, incommensurable frequencies produce\nquasi-periodic, ergodic trajectories, each of which covers its invariant torus\ndensely; the corresponding correlation function of edge modes has fractal\nfeatures. This wealth of behaviors highlights the sharp differences between 4D\nHall droplets and their 2D peers; it also exhibits the dependence of 4D edge\nmodes on the choice of trap, suggesting the existence of observable\nbifurcations due to droplet deformations."
    },
    {
        "anchor": "Ab-initio calculation of all-optical time-resolved calorimetry of\n  nanosized systems: Evidence of nanosecond-decoupling of electron and phonon\n  temperatures: The thermal dynamics induced by ultrashort laser pulses in nanoscale systems,\ni.e. all-optical time-resolved nanocalorimetry is theoretically investigated\nfrom 300 to 1.5 K. We report ab-initio calculations describing the temperature\ndependence of the electron-phonon interactions for Cu nanodisks supported on\nSi. The electrons and phonons temperatures are found to decouple on the ns time\nscale at 10 K, which is two orders of magnitude in excess with respect to that\nfound for standard low-temperature transport experiments. By accounting for the\nphysics behind our results we suggest an alternative route for overhauling the\npresent knowledge of the electron-phonon decoupling mechanism in nanoscale\nsystems by replacing the mK temperature requirements of conventional\nexperiments with experiments in the time-domain.",
        "positive": "Half metallic and insulating phases in BN/Graphene lateral\n  heterostructures: We investigate theoretically the electronic structure of graphene and boron\nnitride (BN) lateral heterostructures, which were fabricated in recent\nexperiments. The first-principles density functional calculation demonstrates\nthat a huge intrinsic transverse electric field can be induced in the graphene\nnanoribbon region, and depends sensitively on the edge configuration of the\nlateral heterostructure. The polarized electric field originates from the\ncharge mismatch at the BN-graphene interfaces. This huge electric field can\nopen a significant bang gap in graphene nanoribbon, and lead to fully\nspinpolarized edge states and induce half-metallic phase in the lateral\nBN/Graphene/BN heterostructure with proper edge configurations."
    },
    {
        "anchor": "Fragile topological phase on the triangular kagome lattice and its\n  bulk-boundary correspondence: We predict and examine various topological states on a two-dimensional (2D)\ntriangular kagome lattice (TKL) using the tight-binding (TB) models and theory\nof topological quantum chemistry (TQC). Firstly, on the basis of TQC, we\ndiagnose band structures with fragile topology and calculate Wilson-loop\nspectra and Hofstadter butterfly spectra to confirm their non-trivial nature.\nSecondly, we examine the bulk-boundary correspondence and find that an\nobstructed-atomic-limit (OAL) insulator hosts fractional corner states without\nbeing accompanied by fragile topological band structures, which implies that\nthe presence of OALs and corner states is not a sufficient condition to fragile\ntopology. Last but not least, we predict a topological phase transition from a\nsecond-order topological phase to a first-order topological phase that can be\nrealized in the TKL under the action of a magnetic field.",
        "positive": "Signatures of a Noise-Induced Quantum Phase Transition in a Mesoscopic\n  Metal Ring: We study a mesoscopic ring with an in-line quantum dot threaded by an\nAharonov-Bohm flux. Zero-point fluctuations of the electromagnetic environment\ncapacitively coupled to the ring, with $\\omega^s$ spectral density, can\nsuppress tunneling through the dot, resulting in a quantum phase transition\nfrom an unpolarized to a polarized phase. We show that robust signatures of\nsuch a transition can be found in the response of the persistent current in the\nring to the external flux as well as to the bias between the dot and the arm.\nParticular attention is paid to the experimentally relevant cases of ohmic\n($s=1$) and subohmic ($s=1/2$) noise."
    },
    {
        "anchor": "Size effect of Ruderman-Kittel-Kasuya-Yosida interaction mediated by\n  electrons in nanoribbons: We calculated the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between\nthe magnetic impurities mediated by electrons in nanoribbons. It was shown that\nthe RKKY interaction is strongly dependent on the width of the nanoribbon and\nthe transverse positions of the impurities. The transverse confinement of\nelectrons is responsible for the above size effect of the RKKY interaction. It\nprovides a potential way to control the RKKY interaction by changing\nnanostructure geometry.",
        "positive": "Stimulus dependence of the collective vibration of atoms in an\n  icosahedral cluster: Molecular dynamics calculations of the vibrational behavior of atoms in a\nLennard-Jones 147-atom cluster revealed that the relaxation and the stability\nof the collective vibration of atoms in the cluster depend on the extent of the\nmechanical disturbance. A relatively larger-scale perturbation will cause a\nfaster decay of the vibration magnitude, the potential and the kinetic energy\ncompared to the vibration stimulated by a small-scale stimulus."
    },
    {
        "anchor": "Engineering transistor-like optical gain in two-dimensional materials\n  with Berry curvature dipoles: Semiconductor transistors are essential elements of electronic circuits as\nthey enable, for example, the isolation or amplification of voltage signals.\nWhile conventional transistors are point-type (lumped-element) devices, it may\nbe highly interesting to realize a distributed transistor-type optical response\nin a bulk material. Here, we show that low-symmetry two-dimensional metallic\nsystems may be the ideal solution to implement such a distributed-transistor\nresponse. To this end, using the semiclassical Boltzmann equation approach, we\ncharacterize the optical conductivity of a two-dimensional material under a\nstatic electric bias. It is found that similar to the nonlinear Hall effect,\nthe electron transport depends on the Berry curvature dipole. Our analysis\nreveals that the electro-optic effect modifies the optical conductivity of the\nmaterial, breaking the electromagnetic reciprocity and yielding a dynamical\nresponse that imitates that of a transistor but in a distributed volume.\nFurthermore, the effective conductivity tensor can be non-Hermitian, opening\nthe possibility of optical gain. To maximize the non-Hermitian response, we\nexplore the specific case of strained twisted bilayer graphene. Our analysis\nreveals that the optical gain for incident light transmitted through the biased\nsystem depends on the light polarization, and can be quite large, especially\nfor multilayer configurations.",
        "positive": "Diffraction and near-zero transmission of flexural phonons at graphene\n  grain boundaries: Graphene grain boundaries are known to affect phonon transport and thermal\nconductivity, suggesting that they may be used to engineer the phononic\nproperties of graphene. Here, the effect of two buckled grain boundaries on\nlong-wavelength flexural acoustic phonons has been investigated as a function\nof angle of incidence using molecular dynamics. The flexural acoustic mode has\nbeen chosen due to its importance to thermal transport. It is found that the\ntransmission through the boundaries is strongly suppressed for incidence angles\nclose to 35$^\\circ$. Also, the grain boundaries are found to act as diffraction\ngratings for the phonons."
    },
    {
        "anchor": "Electric manipulation of domain walls in magnetic Weyl semimetals via\n  the axial anomaly: We show how the axial (chiral) anomaly induces a spin torque on the\nmagnetization in magnetic Weyl semimetals. The anomaly produces an imbalance in\nleft- and right-handed chirality carriers when non-orthogonal electric and\nmagnetic fields are applied. Such imbalance generates a spin density which\nexerts a torque on the magnetization, the strength of which can be controlled\nby the intensity of the applied electric field. We show how this results in an\nelectric control of the chirality of domain walls, as well as in an improvement\nof the domain wall dynamics, by delaying the onset of the Walker breakdown. The\nmeasurement of the electric field mediated changes in the domain wall chirality\nwould constitute a direct proof of the axial anomaly. Additionally, we show how\nquantum fluctuations of electronic Fermi arc states bound to the domain wall\nnaturally induce an effective magnetic anisotropy, allowing for high domain\nwall velocities even if the intrinsic anisotropy of the magnetic Weyl semimetal\nis small.",
        "positive": "Feedback-controlled electromigration for the fabrication of point\n  contacts: Lithographically fabricated point contacts serve as important examples of\nmesoscopic conductors, as electrodes for molecular electronics, and as\nultra-sensitive transducers for mechanical motion. We have developed a\nreproducible technique for fabricating metallic point contacts though\nelectromigration. We employ fast analog feedback in a four-wire configuration\nin combination with slower computer controlled feedback to avoid catastrophic\ninstability. This hybrid system allows electromigration to proceed while\ndissipating approximately constant power in the wire. We are able to control\nthe final resistance of the point contact precisely below 5 k\\Omega\\ and to\nwithin a factor of three when the target resistance approaches 12 k\\Omega\\\nwhere only a single conducting channel remains."
    },
    {
        "anchor": "Critical Level-Spacing Distribution for General Boundary Conditions: It is believed that the semi-Poisson function $P(S)=4S\\exp(-2S)$ describes\nthe normalized distribution of the nearest level-spacings $S$ for critical\nenergy levels at the Anderson metal-insulator transition from quantum chaos to\nintegrability, after an average over four obvious boundary conditions (BC) is\ntaken (Braun {\\it et} {\\it al} \\cite{1}). In order to check whether the\nsemi-Poisson is the correct universal distribution at criticality we\nnumerically compute it by integrating over all possible boundary conditions. We\nfind that although $P(S)$ describes very well the main part of the obtained\ncritical distribution small differences exist particularly in the large $S$\ntail. The simpler crossover between the integrable ballistic and localized\nlimits is shown to be universally characterized by a Gaussian-like $P(S)$\ndistribution instead.",
        "positive": "Contrasting influence of charged impurities on transport and gain in\n  terahertz quantum cascade lasers: Transport and gain properties of a resonant-phonon terahertz quantum cascade\nlaser are calculated using nonequilibrium Green's functions. Impurity\nscattering is shown to be responsible for contrasting nonlinear effects in the\ntransport and the gain properties. For typical doping concentrations, the\ncurrent density is found to be weakly sensitive to the impurity scattering\nstrength. In contrast, the calculated gain is found to be very sensitive to the\nimpurity scattering strength. This difference is attributed to the strong\nmomentum dependence of the long-range coupling to charged impurities.\nSmall-momentum impurity scattering is shown to be responsible for an incoherent\nregime of resonant tunneling processes. These new insights into the crucial\nrole of impurity scattering open a new route of improvement of terahertz\nquantum cascade lasers by engineering of the doping profile."
    },
    {
        "anchor": "Electric-field driven insulating to conducting transition in a\n  mesoscopic quantum dot lattice: We investigate electron transport through a finite two dimensional mesoscopic\nperiodic potential, consisting of an array of lateral quantum dots with\nelectron density controlled by a global top gate. We observe a transition from\nan insulating state at low bias voltages to a conducting state at high bias\nvoltages. The insulating state shows simply activated temperature dependence,\nwith strongly gate voltage dependent activation energy. At low temperatures the\ntransition between the insulating and conducting states becomes very abrupt and\nshows strong hysteresis. The high-bias behavior suggests underdamped transport\nthrough a periodic washboard potential resulting from collective motion.",
        "positive": "Chiral Hall effect in the kink states in topological insulators with\n  magnetic domain walls: In this article we consider the chiral Hall effect due to topologically\nprotected kink states formed in topological insulators at boundaries between\ndomains with differing topological invariants. Such systems include the\nsurfaces of three dimensional topological insulators magnetically doped or in\nproximity with ferromagnets, as well as certain two dimensional topological\ninsulators. We analyze the equilibrium charge current along the domain wall and\nshow that it is equal to the sum of counter-propagating equilibrium currents\nflowing along external boundaries of the domains. In addition, we also\ncalculate a dissipative current along the domain wall when an external voltage\nis applied perpendicularly to the wall."
    },
    {
        "anchor": "Nonlinear dynamics of a functionally graded piezoelectric\n  micro-resonator in the vicinity of the primary resonance: This research is on the nonlinear dynamics of a two-sided electrostatically\nactuated capacitive micro-beam. The microresonator is composed of silicon and\nPZT as a piezoelectric material. PZT is functionally distributed along the\nheight of the micro-beam according to the power law distribution. The\nmicro-resonator is simultaneously subjected to DC piezoelectric and two-sided\nelectrostatic actuations. The DC piezoelectric actuation leads to the\ngeneration of an axial force along the length of the micro-beam and this is\nused as a tuning tool to shift the primary resonance of the micro-resonator.\nThe governing equation of the motion is derived by the minimization of the\nHamiltonian and generalized to the viscously damped systems. The periodic\nsolutions in the vicinity of the primary resonance are detected by means of the\nshooting method and their stability is investigated by determining the\nso-called Floquet exponents of the perturbed motions. The basins of attraction\ncorresponding to three individual periodic orbits are determined. The results\ndepict that the higher the amplitude of the periodic orbit, the smaller is the\narea of the attractor",
        "positive": "Electronic transport in an anisotropic Sierpinski gasket: We present exact results on certain electronic properties of an anisotropic\nSierpinski gasket fractal. We use a tight binding Hamiltonian and work within\nthe formalism of a real space renormalization group (RSRG) method. The\nanisotropy is introduced in the values of the nearest neighbor hopping\nintegrals. An extensive numerical examination of the two terminal transmission\nspectrum and the flow of the hopping integrals under the RSRG iterations\nstrongly suggest that an anisotropic gasket is more conducting than its\nisotropic counter part and that, even a minimal anisotropy in the hopping\nintegrals generate {\\it continuous bands} of eigenstates in the spectrum for\nfinite Sierpinski gaskets of arbitrarily large size. We also discuss the effect\nof a magnetic field threading the planar gasket on its transport properties and\ncalculate the persistent current in the system. The sensitivity of the\npersistent current on the anisotropy and on the band filling is also discussed."
    },
    {
        "anchor": "Coherent electrical control of a single high-spin nucleus in silicon: Nuclear spins are highly coherent quantum objects. In large ensembles, their\ncontrol and detection via magnetic resonance is widely exploited, e.g. in\nchemistry, medicine, materials science and mining. Nuclear spins also featured\nin early ideas and demonstrations of quantum information processing. Scaling up\nthese ideas requires controlling individual nuclei, which can be detected when\ncoupled to an electron. However, the need to address the nuclei via oscillating\nmagnetic fields complicates their integration in multi-spin nanoscale devices,\nbecause the field cannot be localized or screened. Control via electric fields\nwould resolve this problem, but previous methods relied upon transducing\nelectric signals into magnetic fields via the electron-nuclear hyperfine\ninteraction, which severely affects the nuclear coherence. Here we demonstrate\nthe coherent quantum control of a single antimony (spin-7/2) nucleus, using\nlocalized electric fields produced within a silicon nanoelectronic device. The\nmethod exploits an idea first proposed in 1961 but never realized\nexperimentally with a single nucleus. Our results are quantitatively supported\nby a microscopic theoretical model that reveals how the purely electrical\nmodulation of the nuclear electric quadrupole interaction, in the presence of\nlattice strain, results in coherent nuclear spin transitions. The spin\ndephasing time, 0.1 seconds, surpasses by orders of magnitude those obtained\nvia methods that require a coupled electron spin for electrical drive. These\nresults show that high-spin quadrupolar nuclei could be deployed as chaotic\nmodels, strain sensors and hybrid spin-mechanical quantum systems using\nall-electrical controls. Integrating electrically controllable nuclei with\nquantum dots could pave the way to scalable nuclear- and electron-spin-based\nquantum computers in silicon that operate without the need for oscillating\nmagnetic fields.",
        "positive": "Heat-to-Mechanical Energy Conversion in Graphene: Manifestation of\n  Umklapp Enhancement with Strain: Conversion of heat-flux, from a steady state temperature difference, to\nmechanical vibration is demonstrated in graphene nanoribbons using direct\nnon-equilibrium molecular dynamics (NEMD). We observe that this effect is\nindependent of the method of imposing the temperature gradient, heat flux as\nwell as imposed boundary conditions. We propose that simply dividing the\nnanoribbon in long and short sections using a partially immobilized area will\nlead to excitation of long-wavelength vibrations in the long section of the\nnanoribbon. This results in simpler architectures for heat-to-vibration\nconverter devices based on graphene or other 2D materials. Furthermore we\nobserve that applying tensile axial strain to nanoribbons, facilitates\nvibrational instability by reducing the required threshold heat flux or\ntemperature gradient. Finally, we discuss the role played by Umklapp scattering\nfor physical mechanisms behind these observations."
    },
    {
        "anchor": "Topological phase transitions with and without energy gap closing: Topological phase transitions in a three-dimensional (3D) topological\ninsulator (TI) with an exchange field of strength $g$ are studied by\ncalculating spin Chern numbers $C^\\pm(k_z)$ with momentum $k_z$ as a parameter.\nWhen $|g|$ exceeds a critical value $g_c$, a transition of the 3D TI into a\nWeyl semimetal occurs, where two Weyl points appear as critical points\nseparating $k_z$ regions with different first Chern numbers. For $|g|<g_c$,\n$C^\\pm(k_z)$ undergo a transition from $\\pm 1$ to 0 with increasing $|k_z|$ to\na critical value $k_z^{\\tiny C}$. Correspondingly, surface states exist for\n$|k_z| < k_z^{\\tiny C}$, and vanish for $|k_z| \\ge k_z^{\\tiny C}$. The\ntransition at $|k_z| = k_z^{\\tiny C}$ is acompanied by closing of spin spectrum\ngap rather than energy gap.",
        "positive": "The quantum Hall plateau transition at order 1/N: The localization behavior of noninteracting two-dimensional electrons in a\nrandom potential and strong magnetic field is of fundamental interest for the\nphysics of the quantum Hall effect. In order to understand the emergence of\npower-law delocalization near the discrete extended-state energies $E_n = \\hbar\n\\omega_c (n+{1/2})$, we study a generalization of the disorder-averaged\nLiouvillian framework for the lowest Landau level to $N$ flavors of electron\ndensities (N=1 for the physical case). We find analytically the large-N limit\nand 1/N corrections for all disorder strengths: at $N = \\infty$ this gives an\nestimate of the critical conductivity, and at order 1/N an estimate of the\nlocalization exponent $\\nu$. The localization properties of the analytically\ntractable $N \\gg 1$ theory seem to be continuously connected to those of the\nexact quantum Hall plateau transition at $N = 1$."
    },
    {
        "anchor": "Decoherence and lead induced inter-dot coupling in nonequilibrium\n  electron transport through interacting quantum dots: A hierarchical quantum\n  master equation approach: The interplay between interference effects and electron-electron interactions\nin electron transport through an interacting double quantum dot system is\ninvestigated using a hierarchical quantum master equation approach which\nbecomes exact if carried to infinite order and converges well if the\ntemperature is not too low. Decoherence due to electron-electron interactions\nis found to give rise to pronounced negative differential resistance, enhanced\nbroadening of structures in current-voltage characteristics and an inversion of\nthe electronic population. Dependence on gate voltage is shown to be a useful\nmethod of distinguishing decoherence-induced phenomena from effects induced by\nother mechanisms such as the presence of a blocking state. Comparison of\nresults obtained by the hierarchical quantum master equation approach to those\nobtained from the Born-Markov approximation to the Nakajima-Zwanzig equation\nand from the non-crossing approximation to the nonequilibrium Green's function\nreveals the importance of an inter-dot coupling that originates from the energy\ndependence of the conduction bands in the leads and the need for a systematic\nperturbative expansion.",
        "positive": "Optical Response of Finite-Thickness Ultrathin Plasmonic Films: We discuss the optical response peculiarities for ultrathin plasmonic films\nof finite lateral size. Due to their plasma frequency spatial dispersion caused\nby the spatial confinement of the electron motion, the film dielectric\npermittivity tensor is spatially dispersive as well and so nonlocal. Such a\nconfinement induced nonlocality can result in peculiar magneto-optical effects.\nFor example, the frequency dependence of the magnetic permeability of the film\nexhibits a sharp resonance structure shifting to the red as the film aspect\nratio increases. The properly tuned ultrathin plasmonic films of finite lateral\nsize can feature the negative refraction effect in the IR frequency range. We\ndiscuss how to control these magneto-optical properties and show that they can\nbe tuned by adjusting the film chemical composition, plasmonic material\nquality, the aspect ratio, and the surroundings of the film."
    },
    {
        "anchor": "Exciton states and optical properties of CdSe nanocrystals: The optical spectra of CdSe nanocrystals up to 55 A in diameter are analyzed\nin a wide range of energies from the fine structure of the low-energy\nexcitations to the so-called high-energy transitions. We apply a symmetry-based\nmethod in two steps. First we take the tight-binding (TB) parameters from the\nbulk sp^{3}s^{*} TB model, extended to include the spin-orbit interaction. The\nfull single-particle spectra are obtained from an exact diagonalization by\nusing a group-theoretical treatment. The electron-hole interaction is next\nintroduced: Both the Coulomb (direct) and exchange terms are considered. The\nhigh-energy excitonic transitions are studied by computing the electric dipole\ntransition probabilities between single-particle states, while the transition\nenergies are obtained by taking into account the Coulomb interaction. The fine\nstructure of the lowest excitonic states is analyzed by including the\nelectron-hole exchange interaction and the wurtzite crystal-field terms in the\nexciton Hamiltonian. The latter is diagonalized in the single electron-hole\npair excitation subspace of progressively increasing size until convergence.\nThe peaks in the theoretical transition spectra are then used to deduce the\nresonant and nonresonant Stokes shifts, which are compared with their measured\nvalues in photoluminescence experiments. We find that the final results depend\non the crystal-field term, the relative size of the surface and the degree of\nsaturation of the dangling bonds. The results show a satisfactory agreement\nwith the available experimental data.",
        "positive": "Effect of Interface Induced Exchange Fields on Cuprate-Manganite Spin\n  Switches: We examine the anomalous inverse spin switch behavior in\nLa$_{0.7}$Ca$_{0.3}$MnO$_3$ (LCMO)/YBa$_2$Cu$_3$O$_{7-\\delta}$ (YBCO)/LCMO\ntrilayers by combined transport studies and polarized neutron reflectometry.\nMeasuring magnetization profiles and magnetoresistance in an in-plane rotating\nmagnetic field, we prove that, contrary to many accepted theoretical scenarios,\nthe relative orientation between the two LCMO's magnetizations is not\nsufficient to determine the magnetoresistance. Rather the field dependence of\nmagnetoresistance is explained by the interplay between the applied magnetic\nfield and the (exponential tail of the) induced exchange field in YBCO, the\nlatter originating from the electronic reconstruction at the LCMO/YBCO\ninterfaces."
    },
    {
        "anchor": "Cooperative phenomenon in a rippled graphene: Chiral spin guide: We analyze spin scattering in ballistic transport of electrons through a\nripple at a normal incidence of an electron flow. The model of a ripple\nconsists of a curved graphene surface in the form of an arc of a circle\nconnected from the left-hand and right-hand sides to two flat graphene sheets.\nAt certain conditions the curvature induced spin-orbit coupling creates a\ntransparent window for incoming electrons with one spin polarization\nsimultaneously with a backscattering of those with opposite polarization. This\nwindow is equally likely transparent for electrons with spin up and spin down\nthat move in opposite directions. The spin filtering effect being small in one\nripple becomes prominent with the increase of N consequently connected ripples\nthat create a graphene sheet of the sinusoidal type. We present the analytical\nexpressions for spin up (down) transmission probabilities as a function of N\nconnected ripples.",
        "positive": "All silicon Josephson junctions: We have realised laser-doped all-silicon superconducting (S)/ normal metal\n(N) bilayers of tunable thickness and dopant concentration. We observed a\nstrong reduction of the bilayers critical temperature when increasing the\nnormal metal thickness, a signature of the highly transparent S/N interface\nassociated to the epitaxial sharp laser doping profile. We extracted the\ninterface resistance by fitting with the linearised Usadel equations,\ndemonstrating a reduction of one order of magnitude from previous\nsuperconductor/doped Si interfaces. In this well controlled crystalline system\nwe exploited the low resistance S/N interfaces to elaborate all-silicon lateral\nSNS Josephson junctions with long range proximity effect. Their dc transport\nproperties, such as the critical and retrapping currents, could be well\nunderstood in the diffusive regime. Furthermore, this work lead to the\nestimation of important parameters in ultra-doped superconducting Si, such as\nthe Fermi velocity, the coherence length, or the electron-phonon coupling\nconstant, fundamental to conceive an all-silicon superconducting electronics."
    },
    {
        "anchor": "Thermal Switching of Lasing Regimes in Heavily Doped Er3+ Fiber Lasers: A pulsed regime of short-cavity, heavily erbium-doped fiber lasers is of high\ninterest for its possible applications in telecommunications and sensorics.\nHere, we demonstrate these lasers in two configurations, distributed feedback\nlaser and compare it with a classic Fabry-Perot type laser. We have managed to\ncreate lasers that function stably with cavities as small as 50 mm. Pulse\nproperties such as amplitude, frequency and duration, are in a good agreement\nwith our theoretical analysis, which takes into account spontaneous emission.\nWe report the observation of the thermal switching effect, which consists of\nthe pulsing regime changing to CW upon cooling the laser cavities down to the\nliq-uid nitrogen temperature. We theoretically show that this effect may be\nexplained by weakening of the up-conversion process responsible for the pulsed\nregime. The slowing of the up-conversion processes is due to the energy\nmismatch in this process, which is overcome by interaction with phonons. At low\ntemperatures, the number of phonons decreas-es and pulsing switches off.",
        "positive": "Shot-Noise Signatures of 0.7 Structure and Spin in a Quantum Point\n  Contact: We report simultaneous measurement of shot noise and dc transport in a\nquantum point contact as a function of source-drain bias, gate voltage, and\nin-plane magnetic field. Shot noise at zero field exhibits an asymmetry related\nto the 0.7 structure in conductance. The asymmetry in noise evolves smoothly\ninto the symmetric signature of spin-resolved electron transmission at high\nfield. Comparison to a phenomenological model with density-dependent level\nsplitting yields good quantitative agreement."
    },
    {
        "anchor": "Spontaneous formation of time-periodic vortex cluster in nonlinear\n  fluids of light: We demonstrate spontaneous formation of a nonlinear vortex cluster state in a\nmicrocavity exciton-polariton condensate with time-periodic sign flipping of\nits topological charges at the GHz scale. When optically pumped with a\nring-shaped nonresonant laser, the trapped condensate experiences intricate\nhigh-order mode competition and fractures into two distinct trap levels. The\nresulting mode interference leads to robust condensate density beatings with\nperiodic appearance of orderly arranged phase singularities. Our work opens new\nperspectives on creating structured free-evolving light, and singular optics in\nthe strong light-matter coupling regime.",
        "positive": "Criticality of an isotropic-to-smectic transition induced by anisotropic\n  quenched disorder: We report combined optical birefringence and neutron scattering measurements\non the liquid crystal 12CB nanoconfined in mesoporous silicon layers. This\nliquid crystal exhibits strong nematic-smectic coupling responsible for a\ndiscontinuous isotropic-to-smectic phase transition in the bulk state. Confined\nin porous silicon, 12CB is subjected to strong anisotropic quenched disorder: a\nshort-ranged smectic state evolves out of a paranematic phase. This\ntransformation appears continuous, losing its bulk first order character. This\ncontrasts with previously reported observations on liquid crystals under\nisotropic quenched disorder. In the low temperature phase, both orientational\nand translational order parameters obey the same power-law."
    },
    {
        "anchor": "Verification of cosine squared relation of electronic conductance in a\n  biphenyl molecule: The experimentally obtained (Venkataraman {\\em et al}. \\cite{latha}) cosine\nsquared relation of electronic conductance in a biphenyl molecule is verified\ntheoretically within a tight-binding framework. Using Green's function\nformalism we numerically calculate two-terminal conductance as a function of\nrelative twist angle among the molecular rings and find that the results are in\ngood agreement with the experimental observation.",
        "positive": "Tuning paramagnetic spin-excitations of single adatoms: Around 50 years ago, Doniach [Proc. Phys. Soc. 91, 86 (1967)] predicted the\nexistence of paramagnons in nearly ferromagnetic materials, recently measured\nin bulk Pd [Phys. Rev. Lett. 105, 027207 (2010)]. Here we predict the analogous\neffect for single adatoms, namely paramagnetic spin-excitations (PSE). Based on\ntime-dependent density functional theory, we demonstrate that these overdamped\nexcitations acquire a well-defined peak structure in the meV energy region when\nthe adatom's Stoner criterion for magnetism is close to the critical point. In\naddition, our calculations reveal a subtle tunability and enhancement of PSE by\nexternal magnetic fields, exceeding by far the response of bulk paramagnons and\neven featuring the atomic version of a quantum phase transition. We further\ndemonstrate how PSE can be detected as moving steps in the $\\mathrm{d}I/dV$\nsignal of state-of-the-art inelastic scanning tunneling spectroscopy, opening a\npotential route for experimentally accessing fundamental electronic properties\nof non-magnetic adatoms, such as the Stoner parameter."
    },
    {
        "anchor": "Quantum dephasing in a gated GaAs triple quantum dot due to nonergodic\n  noise: We extract the phase coherence of a qubit defined by singlet and triplet\nelectronic states in a gated GaAs triple quantum dot, measuring on timescales\nmuch shorter than the decorrelation time of the environmental noise. In this\nnon-ergodic regime, we observe that the coherence is boosted and several\ndephasing times emerge, depending on how the phase stability is extracted. We\nelucidate their mutual relations, and demonstrate that they reflect the noise\nshort-time dynamics.",
        "positive": "Charge density wave instabilities of type-II Weyl semimetals in a strong\n  magnetic field: Shortly after the discovery of Weyl semimetals properties related to the\ntopology of their bulk band structure have been observed, e.g. signatures of\nthe chiral anomaly and Fermi arc surface states. These essentially single\nparticle phenomena are well understood but whether interesting many-body\neffects due to interactions arise in Weyl systems remains much less explored.\nHere, we investigate the effect of interactions in a microscopic model of a\ntype-II Weyl semimetal in a strong magnetic field. We identify a charge density\nwave (CDW) instability even for weak interactions stemming from the emergent\nnesting properties of the type-II Weyl Landau level dispersion. We map out the\ndependence of this CDW on magnetic field strength. Remarkably, as a function of\ndecreasing temperature a cascade of CDW transitions emerges and we predict\ncharacteristic signatures for experiments."
    },
    {
        "anchor": "Shape control of QDs studied by cross-sectional scanning tunneling\n  microscopy: In this cross-sectional scanning tunneling microscopy study we investigated\nvarious techniques to control the shape of self-assembled quantum dots (QDs)\nand wetting layers (WLs). The result shows that application of an indium flush\nduring the growth of strained InGaAs/GaAs QD layers results in flattened QDs\nand a reduced WL. The height of the QDs and WLs could be controlled by varying\nthe thickness of the first capping layer. Concerning the technique of antimony\ncapping we show that the surfactant properties of Sb result in the preservation\nof the shape of strained InAs/InP QDs during overgrowth. This could be achieved\nby both a growth interrupt under Sb flux and capping with a thin GaAsSb layer\nprior to overgrowth of the uncapped QDs. The technique of droplet epitaxy was\ninvestigated by a structural analysis of strain free GaAs/AlGaAs QDs. We show\nthat the QDs have a Gaussian shape, that the WL is less than 1 bilayer thick,\nand that minor intermixing of Al with the QDs takes place.",
        "positive": "Engineering a Spin-Orbit Bandgap in Graphene-Tellurium Heterostructures: Intensive research has focused on harnessing the potential of graphene for\nelectronic, optoelectronic, and spintronic devices by generating a bandgap at\nthe Dirac point and enhancing the spin-orbit interaction in the graphene layer.\nProximity to heavy p elements is a promising approach; however, their\ninteraction in graphene heterostructures has not been as intensively studied as\nthat of ferromagnetic, noble, or heavy d metals, neither as interlayers nor as\nsubstrates. In this study, the effective intercalation of Te atoms in a\ngraphene on Ir(111) heterostructure is achieved. Combining techniques such as\nlow energy electron diffraction and scanning tunneling microscopy, the\nstructural evolution of the system as a function of the Te coverage is\nelucidated, uncovering up to two distinct phases. The presented angle-resolved\nphotoemission spectroscopy analysis reveals the emergence of a bandgap of about\n240 meV in the Dirac cone at room temperature, which preserves its\ncharacteristic linear dispersion. Furthermore, a pronounced n-doping effect\ninduced by Te in the heterostructure is also observed, and remarkably the\npossibility of tuning the Dirac point energy towards the Fermi level by\nreducing the Te coverage while maintaining the open bandgap is demonstrated.\nSpin-resolved measurements unveil a non-planar chiral spin texture with\nsignificant splitting values for both in-plane and out-of-plane spin\ncomponents. These experimental findings are consistent with the development of\na quantum spin Hall phase, where a Te-enhanced intrinsic spin orbit coupling in\ngraphene surpasses the Rashba one and promotes the opening of the spin-orbit\nbandgap."
    },
    {
        "anchor": "Anomalous resistance overshoot in the integer quantum Hall effect: In this work we report experiments on defined by shallow etching narrow Hall\nbars. The magneto-transport properties of intermediate mobility two-dimensional\nelectron systems are investigated and analyzed within the screening theory of\nthe integer quantized Hall effect. We observe a non-monotonic increase of Hall\nresistance at the low magnetic field ends of the quantized plateaus, known as\nthe overshoot effect. Unexpectedly, for Hall bars that are defined by shallow\nchemical etching the overshoot effect becomes more pronounced at elevated\ntemperatures. We observe the overshoot effect at odd and even integer plateaus,\nwhich favor a spin independent explanation, in contrast to discussion in the\nliterature. In a second set of the experiments, we investigate the overshoot\neffect in gate defined Hall bar and explicitly show that the amplitude of the\novershoot effect can be directly controlled by gate voltages. We offer a\ncomprehensive explanation based on scattering between evanescent incompressible\nchannels.",
        "positive": "An analysis method for transmission measurements of superconducting\n  resonators with applications to quantum-regime dielectric-loss measurements: Superconducting resonators provide a convenient way to measure loss tangents\nof various dielectrics at low temperature. For the purpose of examining the\nmicroscopic loss mechanisms in dielectrics, precise measurements of the\ninternal quality factor at different values of energy stored in the resonators\nare required. Here, we present a consistent method to analyze a LC\nsuperconducting resonator coupled to a transmission line. We first derive an\napproximate expression for the transmission S-parameter $S_{21}$ based on a\ncomplete circuit model. In the weak coupling limit, we show that the internal\nquality factor is reliably determined by fitting the approximate form of\n$S_{21}$. Since the voltage $V$ of the capacitor of the LC circuit is required\nto determine the energy stored in the resonator, we next calculate the relation\nbetween $V$ and the forward propagating wave voltage $V_{in}^+$. Due to the\ndependence of the quality factor on voltage, $V$ is not simply proportional to\n$V_{in}^+$. We find a self-consistent way to determine the relation between $V$\nand $V_{in}^+$, which employs only the fitting parameters for $S_{21}$ and a\nlinear scaling factor. We then examine the resonator transmission in the cases\nof port reflection and impedance mismatch. We find that resonator transmission\nasymmetry is primarily due to the reflection from discontinuity in transmission\nlines. We show that our analysis method to extract the internal quality factor\nis robust in the non-ideal cases above. Finally, we show that the analysis\nmethod on LC resonator can be generalize to arbitrary weakly coupled lumped and\ndistributed resonators. The generalization uses a systematic approximation on\nthe response function based on the pole and zero which are the closest to the\nresonance frequency. This Closest Pole and Zero Method (CPZM) is a valuable\ntool for analyzing physical measurements of high-Q resonators."
    },
    {
        "anchor": "Temperature-dependent screening of the edge state around antidots in the\n  quantum Hall regime: The Aharonov-Bohm (AB) effect in a small array of antidots with large aspect\nratio is investigated in the quantum Hall regime. The evolution with\ntemperature of the AB oscillations in the magnetic field vs gate voltage (B-Vg)\nplane reveals the temperature dependence of the screening. The\nself-consistently screened potential of the compressible band surrounding an\nantidot is observed to gain progressively steeper slope with increasing\ntemperature.",
        "positive": "Squeezed thermal reservoirs as a resource for a nano-mechanical engine\n  beyond the Carnot limit: The efficient conversion of thermal energy to mechanical work by a heat\nengine is an ongoing technological challenge. Since the pioneering work of\nCarnot, it is known that the efficiency of heat engines is bounded by a\nfundamental upper limit, the Carnot limit. Theoretical studies suggest that\nheat engines may be operated beyond the Carnot limit by exploiting stationary,\nnon-equilibrium reservoirs that are characterized by a temperature as well as\nfurther parameters. In a proof-of-principle experiment, we demonstrate that the\nefficiency of a nano-beam heat engine coupled to squeezed thermal noise is not\nbounded by the standard Carnot limit. Remarkably, we also show that it is\npossible to design a cyclic process that allows for extraction of mechanical\nwork from a single squeezed thermal reservoir. Our results demonstrate a\nqualitatively new regime of non-equilibrium thermodynamics at small scales and\nprovide a new perspective on the design of efficient, highly miniaturized\nengines."
    },
    {
        "anchor": "Focused ion beam modification of non-local magnon-based transport in\n  yttrium iron garnet/platinum heterostructures: We study the impact of Ga ion exposure on the local and non-local\nmagnetotransport response in heterostructures of the ferrimagnetic insulator\nyttrium iron garnet and platinum. In particular, we cut the yttrium iron garnet\nlayer in between two electrically separated wires of platinum using a Ga ion\nbeam, and study the ensuing changes in the magnetoresistive response. We find\nthat the non-local magnetoresistance signal vanishes when the yttrium iron\ngarnet film between the Pt wires is fully cut, although the local spin Hall\nmagnetoresistance signal remains finite. This observation corroborates the\nnotion that pure spin currents carried by magnons are crucial for the non-local\nmagnetotransport effects observed in magnetic insulator/metal nanostructures.",
        "positive": "Confined vacuum resonances as artificial atoms with tunable lifetime: Atomically engineered artificial lattices are a useful tool for simulating\ncomplex quantum phenomena, but have so far been limited to the study of\nHamiltonians where electron-electron interactions do not play a role -- but\nit's precisely the regime in which these interactions do matter where\ncomputational times lend simulations a critical advantage over numerical\nmethods. Here, we propose a new platform for constructing artificial matter\nthat relies on the confinement of field-emission resonances, a class of\nvacuum-localized discretized electronic states. We use atom manipulation of\nsurface vacancies in a chlorine-terminated Cu(100) surface to reveal square\npatches of the underlying metal, thereby creating atomically-precise potential\nwells that host particle-in-a-box modes. By adjusting the shape and size of the\nconfining potential, we can access states with different quantum numbers,\nmaking these patches attractive candidates as quantum dots or artificial atoms.\nWe demonstrate that the lifetime of electrons in these engineered states can be\nextended and tuned through modification of the confining potential, either via\natomic assembly or by changing the tip-sample distance. We also demonstrate\ncontrol over a finite range of state-filling, a parameter which plays a key\nrole in the evolution of quantum many-body states. We model the transport\nthrough the localized state to disentangle and quantify the lifetime-limiting\nprocesses, illustrating the critical dependency of the electron lifetime on the\nproperties of the underlying bulk band structure. The interplay with the bulk\nbands also gives rise to negative differential resistance, opening possible\navenues for engineering custom atomic-scale resonant tunnelling diodes, which\nexhibit similar current-voltage characteristics."
    },
    {
        "anchor": "Engineering topological superconductors using surface\n  atomic-layer/molecule hybrid materials: Surface atomic-layer (SAL) superconductors consisting of epitaxially grown\nmetal adatoms on a clean semiconductor surface have been recently established.\nCompared to conventional metal thin films, they have two important features: i)\nspace-inversion symmetry breaking throughout the system and ii) high\nsensitivity to surface adsorption of foreign species. These potentially lead to\nmanifestation of the Rashba effect and a Zeeman field exerted by adsorbed\nmagnetic organic molecules. After introduction of archetypical SAL\nsuperconductor Si(111)-(root7xroot3)-In, we describe how these features are\nutilized to engineer topological superconductor with Majorana fermions, and\ndiscuss its promises and expected challenges.",
        "positive": "Magnetic Vortex Core Dynamics in a Ferromagnetic Dot: We report direct imaging by means of x-ray photoemission electron microscopy\nof the dynamics of magnetic vortices confined in micron-size circular Permalloy\ndots that are 30 nm thick. The vortex core positions oscillate on a 10-ns\ntimescale in a self-induced magnetostatic potential well after the in-plane\nmagnetic field is turned off. The measured oscillation frequencies as a\nfunction of the aspect ratio (thickness/radius) of the dots are in agreement\nwith theoretical calculations presented for the same geometry."
    },
    {
        "anchor": "Characterizing Transition-Metal Dichalcogenide Thin-Films using\n  Hyperspectral Imaging and Machine Learning: Atomically thin polycrystalline transition-metal dichalcogenides (TMDs) are\nrelevant to both fundamental science investigation and applications. TMD\nthin-films present uniquely difficult challenges to effective nanoscale\ncrystalline characterization. Here we present a method to quickly characterize\nthe nanocrystalline grain structure and texture of monolayer WS2 films using\nscanning nanobeam electron diffraction coupled with multivariate statistical\nanalysis of the resulting data. Our analysis pipeline is highly generalizable\nand is a useful alternative to the time consuming, complex, and\nsystem-dependent methodology traditionally used to analyze spatially resolved\nelectron diffraction measurements.",
        "positive": "Spontaneous Coherence in a Cold Exciton Gas: Excitons, bound pairs of electrons and holes, form a model system to explore\nthe quantum physics of cold bosons in solids. Cold exciton gases can be\nrealized in a system of indirect excitons, which can cool down below the\ntemperature of quantum degeneracy due to their long lifetimes. Here, we report\non the measurement of spontaneous coherence in a gas of indirect excitons. We\nfound that extended spontaneous coherence of excitons emerges in the region of\nthe macroscopically ordered exciton state and in the region of vortices of\nlinear polarization. The coherence length in these regions is much larger than\nin a classical gas, indicating a coherent state with a much narrower than\nclassical exciton distribution in momentum space, characteristic of a\ncondensate. We also observed phase singularities in the coherent exciton gas.\nExtended spontaneous coherence and phase singularities emerge when the exciton\ngas is cooled below a few Kelvin."
    },
    {
        "anchor": "Quantum oscillations with magnetic hysteresis observed in CeTe$_{3}$\n  thin films: We have performed magnetotransport measurements in CeTe$_{3}$ thin films down\nto $0.2~{\\rm K}$. It is known that CeTe$_{3}$ has two magnetic transitions at\n$T_{\\rm N1} \\approx 3~{\\rm K}$ and $T_{\\rm N2} \\approx 1~{\\rm K}$. A clear\nShubnikov-de-Haas (SdH) oscillation was observed at $4~{\\rm K}$, demonstrating\nthe strong two-dimensional nature in this material. Below $T_{\\rm N2}$, the SdH\noscillation has two frequencies, indicating that the Fermi surface could be\nslightly modulated due to the second magnetic transition. We also observed a\nmagnetic hysteresis in the SdH oscillation below $T_{\\rm N1}$. Especially,\nthere is a unique spike in the magnetoresistance at $B \\approx 0.6~{\\rm T}$\nonly when the magnetic field is swept from a high enough field (more than\n$2~{\\rm T}$) to zero field.",
        "positive": "Molecular prototypes for spin-based CNOT quantum gates: We show that a chemically engineered structural asymmetry in [Tb2] molecular\nclusters renders the two weakly coupled Tb3+ spin qubits magnetically\ninequivalent. The magnetic energy level spectrum of these molecules meets then\nall conditions needed to realize a universal CNOT quantum gate."
    },
    {
        "anchor": "Dynamical polarization of graphene under strain: We study the dependence of the plasmon dispersion relation of graphene on\napplied uniaxial strain. Besides electron correlation at the RPA level, we also\ninclude local field effects specific for the honeycomb lattice. As a\nconsequence of the two-band character of the electronic band structure, we find\ntwo distinct plasmon branches. We recover the square-root behavior of the\nlow-energy branch, and find a nonmonotonic dependence of the strain-induced\nmodification of its stiffness, as a function of the wavevector orientation with\nrespect to applied strain.",
        "positive": "Railway switch transport model: We propose a simple model of coupled heat and particle transport based on a\nzero-dimensional classical deterministic dynamics which is reminiscent of a\nrailway switch whose action is only a function of the particle's energy. It is\nshown that already in the minimal three-terminal model, where the second\nterminal is considered as a probe with zero net particle and heat currents, one\ncan find extremely asymmetric Onsager matrices as a consequence of\ntime-reversal symmetry breaking of the model. This minimalistic transport model\nprovides a better understanding of thermoelectric heat engines in the presence\nof time-reversal symmetry breaking."
    },
    {
        "anchor": "Designing Efficient Metal Contacts to Two-Dimensional Semiconductors\n  MoSi$_2$N$_4$ and WSi$_2$N$_4$ Monolayers: Metal contacts to two-dimensional (2D) semiconductors are ubiquitous in\nmodern electronic and optoelectronic devices. Such contacts are, however, often\nplagued by strong Fermi level pinning (FLP) effect which reduces the tunability\nof the Schottky barrier height (SBH) and degrades the performance of\n2D-semiconductor-based devices. In this work, we show that monolayer\nMoSi$_2$N$_4$ and WSi$_2$N$_4$ - a recently synthesized 2D material class with\nexceptional mechanical and electronic properties - exhibit strongly suppressed\nFLP and wide-range tunable SBH when contacted by metals. An exceptionally large\nSBH slope parameter of S=0.7 is obtained, which outperform the vast majority of\nother 2D semiconductors. Such surprising behavior arises from the unique\nmorphology of MoSi$_2$N$_4$ and WSi$_2$N$_4$. The outlying Si-N layer forms a\nnative atomic layer that protects the semiconducting inner-core from the\nperturbance of metal contacts, thus suppressing the FLP. Our findings reveal\nthe potential of MoSi$_2$N$_4$ and WSi$_2$N$_4$ monolayers as a novel 2D\nmaterial platform for designing high-performance and energy-efficient 2D\nnanodevices.",
        "positive": "The Superconducting Quantum Interference Proximity Transistor (SQUIPT): In this article we review the basic theoretical properties of a hybrid\nsuperconducting interferometer which exploits the phase dependence of the\ndensity of states of a metallic nanowire placed in good electric contact with a\nsuperconductor to achieve high sensitivity to magnetic flux. The operation of a\nprototype structure based on this principle, the superconducting quantum\ninterference proximity transistor (SQUIPT), has been recently reported. Limited\npower dissipation joined with the opportunity to access single-spin detection\nmake this interferometer attractive for the investigation of the switching\ndynamics of individual magnetic nanoparticles. The noise behavior of the device\nis presented as well, where the feasibility of this structure as a single-spin\ndetector is also briefly addressed. In the final part we present the response\nof a real SQUIPT device."
    },
    {
        "anchor": "Phonon-Mediated Phase Transitions in Two-Dimensional Driven-Dissipative\n  Systems: We develop a two-dimensional stochastic dissipative theory for the\ndescription of the transport of exciton polaritons accounting for their\ninteraction with the environment of acoustic phonons. Our approach is based on\nthe explicit modeling of the corresponding microscopic processes using a Monte\nCarlo framework rather than modeling from phenomenological principles. We show\nthe dynamic formation of a condensate and investigate its characteristics,\nincluding threshold-like behavior in populations and the formation of spatial\nand temporal coherence at different temperatures of the environment and\naccounting for the stimulated nonlinear scattering, caused by\nsystem-environment interaction. The spatial coherence reveals a transition from\nan exponential to polynomial decay which can be attributed to the\nBerezinskii-Kosterlitzh-Thouless-like phase.",
        "positive": "Aharonov-Bohm interferometry with quantum dots: scattering approach\n  versus tunneling picture: We address the question of how to model electron transport through closed\nAharonov-Bohm interferometers which contain quantum dots. By explicitly\nstudying interferometers with one and two quantum dots, we establish the\nconnection between a tunneling-Hamiltonian formulation on the one hand and a\nscattering-matrix approach on the other hand. We prove that, under certain\ncircumstances, both approaches are equivalent, i.e., both types of models can\ndescribe the same experimental setups. Furthermore, we analyze how the\ninterplay of the Aharonov-Bohm phase and the orbital phase associated with the\nlengths of the interferometers' arms affect transport properties."
    },
    {
        "anchor": "Surface Scattering via Bulk Continuum States in the 3D Topological\n  Insulator Bi$_{2}$Se$_{3}$: We have performed scanning tunneling microscopy and differential tunneling\nconductance ($dI/dV$) mapping for the surface of the three dimensional\ntopological insulator Bi$_{2}$Se$_{3}$. The fast Fourier transformation applied\nto the $dI/dV$ image shows an electron interference pattern near Dirac node\ndespite the general belief that the backscattering is well suppressed in the\nbulk energy gap region. The comparison of the present experimental result with\ntheoretical surface and bulk band structures shows that the electron\ninterference occurs through the scattering between the surface states near the\nDirac node and the bulk continuum states.",
        "positive": "Experimental Demonstration Of Scanned Spin-Precession Microscopy: Progress in spintronics has been aided by characterization tools tailored to\ncertain archetypical materials. New device structures and materials will\nrequire characterization tools that are material independent, provide\nsufficient resolution to image locally-varying spin properties and enable\nsubsurface imaging. Here we report the demonstration of a novel spin-microscopy\ntool based on the variation of a global spin-precession signal in response to\nthe localized magnetic field of a scanned probe. We map the local spin density\nin optically pumped GaAs from this spatially-averaged signal with a resolution\nof 5.5 microns. This methodology is also applicable to other spin properties\nand its resolution can be improved. It can extend spin microscopy to device\nstructures not accessible by other techniques, such as buried interfaces and\nnon-optically active materials, due to the universal nature of magnetic\ninteractions between the spins and the probe."
    },
    {
        "anchor": "Mesoscopic physics of nanomechanical systems: Nanomechanics has brought mesoscopic physics into the world of vibrations.\nBecause nanomechanical systems are small, fluctuations are significant, the\nvibrations become nonlinear already for comparatively small amplitudes, and new\nmechanisms of dissipation come into play. At the same time, the exquisite\ncontrol of these systems makes them a platform for studying many problems of\nclassical and quantum physics far from thermal equilibrium in a\nwell-characterized setting. This review describes, at a conceptual level, basic\ntheoretical ideas and explicative experiments pertaining to mesoscopic physics\nof nanomechanical systems. Major applications of nanomechanics in science and\ntechnology are also outlined. A broad range of phenomena related to the\nconservative as well as dissipative nonlinearity and fluctuations are discussed\nwithin a unifying framework. They include the linear response of single and\ncoupled vibrational modes as well as nonlinear effects of periodic driving.\nSuch driving breaks the continuous time-translation symmetry and the detailed\nbalance, with conspicuous consequences for fluctuations, particularly in the\npresence of the driving-induced bi- and multistability. Mathematical techniques\nare described in the appendices to streamline the reading, but also to provide\nan introduction to the theory. The goal of the review is to show the richness\nof the physics at work. The continuous experimental and theoretical advances\nmake nanomechanical systems a vibrant area of research, with many new phenomena\nto discover.",
        "positive": "Josephson junction transmission lines as tunable artificial crystals: We investigate one-dimensional Josephson junction arrays with generalized\nunit cells as a circuit approach to engineer microwave band gaps. An array\ndescribed by a lattice with a basis can be designed to have a gap in the\nelectromagnetic spectrum, in full analogy to electronic band gaps in diatomic\nor many-atomic crystals. We derive the dependence of this gap on the array\nparameters in the linear regime, and suggest experimentally feasible designs to\nbring the gap below the single junction plasma frequency. The gap can be tuned\nin a wide frequency range by applying external flux, and it persists in the\npresence of small imperfections."
    },
    {
        "anchor": "Protected gap closing in Josephson junctions constructed on Bi$_2$Te$_3$\n  surface: On the road of searching for Majorana zero modes (MZMs) in topological\ninsulator-based Josephson junctions, a highly-sought signature is the protected\nfull transparency of electron transport through the junctions due to the\nexistence of the MZMs, associated with complete gap closing between the\nelectron-like and hole-like Andreev bound states (ABSs). Here, we present\ndirect experimental evidence of gap closing and full transparency in single\nJosephson junctions constructed on the surface of three-dimensional topological\ninsulator (3D TI) Bi$_2$Te$_3$. Our results demonstrate that the 2D surface of\n3D TIs provides a promising platform for hosting and manipulating MZMs.",
        "positive": "Signatures in the conductance for phase transitions in excitonic systems: We analyse two phase transitions in exciton bilayer systems: a topological\nphase transition to a phase which hosts Majorana fermions and a phase\ntransition to a Wigner crystal. Using generic simple models for the different\nphases we discuss the conductance properties of the latter when contacted to\nmetallic leads and demonstrate the possibility to observe the different phase\ntransitions by simple conductance measurements."
    },
    {
        "anchor": "Observation of zero-point quantum fluctuations of a single-molecule\n  magnet through the relaxation of its nuclear spin bath: A single-molecule magnet placed in a magnetic field perpendicular to its\nanisotropy axis can be truncated to an effective two-level system, with easily\ntunable energy splitting. The quantum coherence of the molecular spin is\nlargely determined by the dynamics of the surrounding nuclear spin bath. Here\nwe report the measurement of the nuclear spin--lattice relaxation in a single\ncrystal of the single-molecule magnet Mn$_{12}$-ac, at $T \\approx 30$ mK in\nperpendicular fields $B_{\\perp}$ up to 9 T. Although the molecular spin is in\nits ground state, we observe an increase of the nuclear relaxation rates by\nseveral orders of magnitude up to the highest $B_{\\perp}$. This unique finding\nis a consequence of the zero-point quantum fluctuations of the Mn$_{12}$-ac\nspin, which allow it to efficiently transfer energy from the excited nuclear\nspin bath to the lattice. Our experiment highlights the importance of quantum\nfluctuations in the interaction between an `effective two-level system' and its\nsurrounding spin bath.",
        "positive": "Mesoscopic Fluctuations of Coulomb Drag of Composite Fermions: We present the first experimental study of mesoscopic fluctuations of Coulomb\ndrag in a system with two layers of composite fermions, which are seen when\neither the magnetic field or carrier concentration are varied. These\nfluctuations cause an alternating sign of the average drag. We study these\nfluctuations at different temperatures to establish the dominant dephasing\nmechanism of composite fermions."
    },
    {
        "anchor": "Electromagnetic response in spiral magnets and emergent inductance: Emergent electromagnetism in magnets originates from the strong coupling\nbetween conduction electron spins and those of noncollinear ordered moments and\nthe consequent Berry phase. This offers possibilities to develop new functions\nof quantum transport and optical responses. The emergent inductance in spiral\nmagnets is an example recently proposed and experimentally demonstrated, used\nthe emergent electric field induced by alternating currents. However, the\nmicroscopic theory of this phenomenon is missing, which should reveal the\nfactors to determine the magnitude, sign, frequency dependence, and\nnonlinearity of the inductance L. Here we theoretically study electromagnetic\nresponses of spiral magnets taking into account their collective modes. In\nsharp contrast to the collinear spin-density wave, the system remains metallic\neven in one-dimension, and the canonical conjugate relation of uniform\nmagnetization and phason coordinate plays an essential role, determining the\nproperties of L. This result opens a way to design the emergent inductance of\ndesired properties.",
        "positive": "Observation of Partially Suppressed Shot Noise in Hopping Conduction: We have observed shot noise in the hopping conduction of two dimensional\ncarriers confined in a p-type SiGe quantum well at a temperature of 4K.\nMoreover, shot noise is suppressed relative to its ``classical'' value 2eI by\nan amount that depends on the length of the sample and carrier density, which\nwas controlled by a gate voltage. We have found a suppression factor to the\nclassical value of about one half for a 2 $\\mu$m long sample, and of one fifth\nfor a 5 $\\mu$m sample. In each case, the factor decreased slightly as the\ndensity increased toward the insulator-metal transition. We explain these\nresults in terms of the characteristic length ($\\simeq 1\\mu$m in our case) of\nthe inherent inhomogeneity of hopping transport."
    },
    {
        "anchor": "Non-Equilibrium Green Functions in Electronic Device Modeling: We present an overview of electronic device modeling using non-equilibrium\nGreen function techniques. The basic approach developed in the early 1970s has\nbecome increasingly popular during the last 10 years. The rise in popularity\nwas driven first by the experimental investigations of mesoscopic physics made\npossible by high quality semiconductor heterostructures grown by molecular beam\nepitaxy. The theory has continuously been adapted to address current systems of\ninterest moving from the mesoscopic physics of the late 1980s to single\nelectronics to molecular electronics to nanoscaled FETs. We give an overview of\nthe varied applications. We provide a tutorial level derivation of the polar\noptical phonon self-energy [1]. Then, focusing on issues of a non-orthogonal\nbasis used in molecular electronics calculations, we derive and the basic Green\nfunction expressions starting from their definitions in second quantized form\nin a non-orthogonal basis. We derive the equations of motion for the retarded\nGreen function G^R and the correlation function G^<, and we derive the standard\nexpressions for the electron density and the current that are in widespread\nuse. We point out common approximations and open questions of which one finds\nlittle discussion in the literature.",
        "positive": "The dynamics of bimeron skyrmions in easy-plane magnets induced by a\n  spin supercurrent: We theoretically study the interaction of an isolated bimeron skyrmion in\nquasi-two-dimensional easy-plane magnets with a surrounding spin superfluid\nassociated with spontaneously broken U(1) spin-rotational symmetry, revealing\nthat skyrmion energy depends on the local spin current flowing in its\nbackground. The finding leads us to propose to manipulate a skyrmion energy\nlandscape via a spin supercurrent, which can be controlled non-locally by\nvarying the magnitudes of spin-current injection and ejection through the\nboundaries. Two exemplary cases are discussed: a steady-state motion of a\nskyrmion induced by a uniform force and a skyrmion motion localized along a\none-dimensional racetrack. We envision that a skyrmion interacting with a spin\nsuperfluid can serve as a robust point-like information carrier that can be\noperated with minimal dissipation."
    },
    {
        "anchor": "Experimental realization of a Fabry-Perot-type interferometer by\n  co-propagating edge states in the quantum Hall regime: A Fabry-Perot-type interferometer is experimentally realized for electrons in\na semiconductor device. A special experimental geometry creates interference\nconditions for co-propagating electrons in quantum Hall edge states, which\nresults in oscillations of the current through the device. The visibility of\nthese oscillations is found to increase at the high-field edge of the quantum\nHall plateau.",
        "positive": "Signature of band inversion in the antiferromagnetic phase of axion\n  insulator candidate EuIn2As2: We have performed angle-resolved photoemission spectroscopy on EuIn2As2 which\nis predicted to be an axion insulator in the antiferromagnetic state. By\nutilizing soft-x-ray and vacuum-ultraviolet photons, we revealed a\nthree-dimensional hole pocket centered at the Gamma point of bulk Brillouin\nzone together with a heavily hole-doped surface state in the paramagnetic\nphase. Upon entering the antiferromagnetic phase, the band structure exhibits a\nmarked reconstruction characterized by the emergence of a \"M\"-shaped bulk band\nnear the Fermi level. The qualitative agreement with first-principles\nband-structure calculations suggests the occurrence of bulk-band inversion at\nthe Gamma point in the antiferromagnetic phase. We suggest that EuIn2As2\nprovides a good opportunity to study the exotic quantum phases associated with\npossible axion-insulator phase."
    },
    {
        "anchor": "SAW interdigitated transducers as topological mechanical metamaterial: A lattice model is developed to describe the mechanical displacement of and\ncurrent through each electrode of a surface acoustic wave (SAW) interdigitated\ntranducer (IDT). Each electrode of an IDT is treated as a mass connected\nmechanically to its neighbors with a spring and electrically with a capacitor.\nSimulations for the electrical admittance of a typical SAW IDT are performed\nand compared with the results of an accurate finite element method simulation.\nThe utility of this lattice model is demonstrated by simulating the admittance\nof an IDT structure known as a hiccup resonator, which has a mode in the center\nof the band gap. It is shown here that this mode is a topologically protected\nedge state described by the 1D Su-Schrieffer-Heeger (SSH) model. Hiccup\nresonators have been used in commercial products for decades, and as such it\nmay considered the first mass-produced topological mechanical metamaterial.",
        "positive": "Electric field tunable superconductor-semiconductor coupling in Majorana\n  nanowires: We study the effect of external electric fields on\nsuperconductor-semiconductor coupling by measuring the electron transport in\nInSb semiconductor nanowires coupled to an epitaxially grown Al superconductor.\nWe find that the gate voltage induced electric fields can greatly modify the\ncoupling strength, which has consequences for the proximity induced\nsuperconducting gap, effective g-factor, and spin-orbit coupling, which all\nplay a key role in understanding Majorana physics. We further show that level\nrepulsion due to spin-orbit coupling in a finite size system can lead to\nseemingly stable zero bias conductance peaks, which mimic the behavior of\nMajorana zero modes. Our results improve the understanding of realistic\nMajorana nanowire systems."
    },
    {
        "anchor": "Spatio-Temporal Imaging of the Acoustic Field Emitted by a Single Copper\n  Nanowire Copper Nanowires Fabrication: The monochromatic and geometrically anisotropic acoustic field generated by\n400 nm and 120 nm diameter copper nanowires simply dropped on a 10 $\\mu$m\nsilicon membrane is investigated in transmission using three-dimensional\ntime-resolved femtosecond pump-probe experiments. Two pump-probe time-resolved\nexperiments are carried out at the same time on both side of the silicon\nsubstrate. In reflection, the first radial breathing mode of the nanowire is\nexcited and detected. In transmission, the longitudinal and shear waves are\nobserved. The longitudinal signal is followed by a monochromatic component\nassociated with the relaxation of the nanowire's first radial breathing mode.\nFinite Difference Time Domain (FDTD) simulations are performed and accurately\nreproduce the diffracted field. A shape anisotropy resulting from the large\naspect ratio of the nanowire is detected in the acoustic field. The orientation\nof the underlying nanowires is thus acoustically deduced.",
        "positive": "Symmetry breaking in a mechanical resonator made from a carbon nanotube: Nanotubes behave as semi-flexible polymers in that they can bend by a\nsizeable amount. When integrating a nanotube in a mechanical resonator, the\nbending is expected to break the symmetry of the restoring potential. Here we\nreport on a new detection method that allows us to demonstrate such symmetry\nbreaking. The method probes the motion of the nanotube resonator at nearly\nzero-frequency; this motion is the low-frequency counterpart of the second\novertone of resonantly excited vibrations. We find that symmetry breaking leads\nto the spectral broadening of mechanical resonances, and to an apparent quality\nfactor that drops below 100 at room temperature. The low quality factor at room\ntemperature is a striking feature of nanotube resonators whose origin has\nremained elusive for many years. Our results shed light on the role played by\nsymmetry breaking in the mechanics of nanotube resonators."
    },
    {
        "anchor": "\"Listening\" to the spin noise of conduction electrons in bulk n:GaAs: We report a comprehensive study of stochastic electron spin fluctuations --\nspin noise -- in lightly doped ($n$-type) bulk GaAs, which are measured using\nsensitive optical magnetometry based on off-resonant Faraday rotation.\nFrequency spectra of electron spin noise are studied as a function of electron\ndensity, magnetic field, temperature, probe laser wavelength and intensity, and\ninteraction volume. Electron spin lifetimes $\\tau_s$ are inferred from the\nwidth of the spin noise spectra, and are compared with direct measurements of\n$\\tau_s$ using conventional Hanle effect methods. Both methods reveal a strong\nand similar dependence of $\\tau_s$ on the wavelength and intensity of the probe\nlaser, highlighting the undesired influence of sub-bandgap absorption effects\non the nominally `non-perturbative' spin noise measurements. As a function of\ntemperature, the spin noise power increases approximately linearly from 1.5 K\nto 30 K, as expected for degenerate electrons obeying Fermi-Dirac statistics,\nbut with an additional zero-temperature offset. Finally, as the cross-sectional\narea of the probe laser shrinks and fewer electrons are probed, the measured\nFaraday rotation fluctuations due to electron spin noise are shown to increase,\nas expected.",
        "positive": "Self-induced inverse spin Hall effect in ferromagnets: demonstration\n  through non-monotonous temperature-dependence in permalloy: We investigated the self-induced inverse spin Hall effect in ferromagnets.\nTemperature (T), thickness (t) and angular-dependent measurements of transverse\nvoltage in spin pumping experiments were performed with permalloy films.\nResults revealed non-monotonous T-dependence of the self-induced transverse\nvoltage. Qualitative agreement was found with first-principle calculations\nunravelling the skew scattering, side-jump, and intrinsic contributions to the\nT-dependent spin Hall conductivity. Experimental data were similar whatever the\nmaterial in contact with permalloy (oxides or metals), and revealed an increase\nof produced current with t, demonstrating a bulk origin of the effect."
    },
    {
        "anchor": "Plasmon excitations in mixed metallic nanoarrays: We study the plasmonic properties of arrays of atomic chains which comprise\nnoble (Cu, Ag, and Au) and transition (Pd, Pt) metal atoms using time-dependent\ndensity-functional theory. We show that the response to the electromagnetic\nradiation is related to both physics, the geometry-dependent confinement of\nsp-valence electrons, and chemistry, the energy position of d-electrons in the\ndifferent atomic species and the hybridization between d and sp electrons. As a\nresult it is possible to tune the position of the surface plasmon resonance,\nsplit it to several peaks, and eventually achieve broadband absorption of\nradiation. Mixing the arrays with transition metals can strongly attenuate the\nplasmonic behaviour. We analyze the origin of these phenomena and show that\nthey arise from rich interactions between single-particle electron-hole and\ncollective electron excitations. The tunability of the plasmonic response of\narrays of atomic chains, which can be realized on solid surfaces, opens wide\npossibilities for their applications. In the present study we obtain guidelines\nhow the desired properties can be achieved.",
        "positive": "Enhancement of Spin Currents in a Lattice near the Curie Point: We show that pure spin currents carried by conduction electrons injected into\na paramagnetic lattice of mutually interacting localized magnetic moments can\nbe enhanced close to the Curie temperature by the exchange interaction between\nthe lattice sites and the non vanishing spin density associated with the spin\ncurrent. The latter partially aligns the magnetic moments of the lattice,\ngenerating a flow of paramagnons that contribute to the total spin current."
    },
    {
        "anchor": "Electrical control of intervalley scattering in graphene via the charge\n  state of defects: We study the intervalley scattering in defected graphene by low-temperature\ntransport measurements. The scattering rate is strongly suppressed when defects\nare charged. This finding highlights \"screening\" of the short-range part of a\npotential by the long-range part. Experiments on calcium-adsorbed graphene\nconfirm the role of a long-range Coulomb potential. This effect is applicable\nto other multivalley systems, provided that the charge state of a defect can be\nelectrically tuned. Our result provides a means to electrically control valley\nrelaxation and has important implications in valley dynamics in valleytronic\nmaterials.",
        "positive": "Sensitive Magnetic Force Detection with a Carbon Nanotube Resonator: We propose a technique for sensitive magnetic point force detection using a\nsuspended carbon nanotube (CNT) mechanical resonator combined with a magnetic\nfield gradient generated by a ferromagnetic gate electrode. Numerical\ncalculations of the mechanical resonance frequency show that single Bohr\nmagneton changes in the magnetic state of an individual magnetic molecule\ngrafted to the CNT can translate to detectable frequency shifts, on the order\nof a few kHz. The dependences of the resonator response to device parameters\nsuch as length, tension, CNT diameter, and gate voltage are explored and\noptimal operating conditions are identified. A signal-to-noise analysis shows\nthat in principle, magnetic switching at the level of a single Bohr magneton\ncan be read out in a single shot on timescales as short as 10 microseconds.\nThis force sensor should enable new studies of spin dynamics in isolated single\nmolecule magnets, free from the crystalline or ensemble settings typically\nstudied."
    },
    {
        "anchor": "Charge Transport in a Quantum Electromechanical System: We describe a quantum electromechanical system(QEMS) comprising a single\nquantum dot harmonically bound between two electrodes and facilitating a\ntunneling current between them. An example of such a system is a fullerene\nmolecule between two metal electrodes [Park et al., Nature, 407, 57 (2000)].\nThe description is based on a quantum master equation for the density operator\nof the electronic and vibrational degrees of freedom and thus incorporates the\ndynamics of both diagonal (population) and off diagonal (coherence) terms. We\nderive coupled equations of motion for the electron occupation number of the\ndot and the vibrational degrees of freedom, including damping of the vibration\nand thermo-mechanical noise. This dynamical description is related to\nobservable features of the system including the stationary current as a\nfunction of bias voltage.",
        "positive": "The role of faceting and elongation on the magnetic anisotropy of\n  magnetite Fe3O4 nanocrystals: Fe3O4 nanoparticles are one of the most promising candidates for biomedical\napplications such as magnetic hyperthermia and theranostics due to their\nbio-compatibility, structural stability and good magnetic properties. However,\nmuch is unknown about the nanoscale origins of the observed magnetic properties\nof particles due to the dominance of surface and finite size effects. Here we\nhave developed an atomistic spin model of elongated magnetite nanocrystals to\nspecifically address the role of faceting and elongation on the magnetic shape\nanisotropy. We find that for faceted particles simple analytical formulae\noverestimate the magnetic shape anisotropy and that the underlying cubic\nanisotropy makes a significant contribution to the energy barrier for\nmoderately elongated particles. Our results enable a better estimation of the\neffective magnetic anisotropy of highly crystalline magnetite nanoparticles and\nis a step towards quantitative prediction of the heating effects of magnetic\nnanoparticles."
    },
    {
        "anchor": "CMOS-compatible graphene photodetector covering all optical\n  communication bands: Optical interconnects are becoming attractive alternatives to electrical\nwiring in intra- and inter-chip communication links. Particularly, the\nintegration with silicon complementary metal-oxide-semiconductor (CMOS)\ntechnology has received considerable interest due to the ability of\ncost-effective integration of electronics and optics on a single chip. While\nsilicon enables the realization of optical waveguides and passive components,\nthe integration of another, optically absorbing, material is required for\nphotodetection. Germanium or compound semiconductors are traditionally used for\nthis purpose; their integration with silicon technology, however, faces major\nchallenges. Recently, graphene has emerged as a viable alternative for\noptoelectronic applications, including photodetection. Here, we demonstrate an\nultra-wideband CMOS-compatible photodetector based on graphene. We achieve\nmulti-gigahertz operation over all fiber-optic telecommunication bands, beyond\nthe wavelength range of strained germanium photodetectors, whose responsivity\nis limited by their bandgap. Our work complements the recent demonstration of a\nCMOS-integrated graphene electro-optical modulator, paving the way for\ncarbon-based optical interconnects.",
        "positive": "Numerical guidelines for setting up a general purpose k.p simulator with\n  applications to quantum dot heterostructures and topological insulators: The k.p perturbation method for determination of electronic structure first\npioneered by Kohn and Luttinger continues to provide valuable insight to\nseveral band structure features. This method has been adopted to\nheterostructures confined up to three directions. In this paper, numerical\ndetails of setting up a k.p Hamiltonian using the finite difference\napproximation for such confined nanostructures is explicitly demonstrated.\nNanostructures belonging to two symmetry classes namely cubic zincblende and\nrhombohedral crystals are considered. Rhombohedral crystals, of late, have\ngained prominence as candidates for the recently discovered topological\ninsulator (TI) class of materials. Lastly the incorporation of strain field to\nthe k.p Hamiltonian and matrix equations for computing the intrinsic and\nexternally applied strain in heterostructures within a continuum approximation\nis shown. Two applications are considered 1)Computation of the eigen states of\na multi-million zincblende InAs quantum dot with a stress-reducing InGaAs layer\nof varying Indium composition embedded in a GaAs matrix and 2)Dispersion of a\nrhombohedral topological insulator Bi$_{2}$Se$_{3}$ film."
    },
    {
        "anchor": "Electron Transfer Methods in Open Systems: Utilization of electron transfer methods for description of quantum transport\nis popular due to simplicity of the formulation and its ability to account for\nbasic physics of electron exchange between system and baths. At the same time,\nnecessity to go beyond simple golden rule-type expressions for rates was\nindicated in the literature and ad hoc formulations were proposed. Similarly,\nkinetic schemes for quantum transport beyond usual second order\nLindblad/Redfield considerations were discussed. Here we utilize recently\nintroduced by us nonequilibrium Hubbard Green's functions diagrammatic\ntechnique to analyze construction of rates in open systems. We show that\nprevious considerations for rates of second and fourth order can be obtained as\na particular case of zero and second order Green's function diagrammatic series\nwith bare diagrams. We discuss limitations of previous considerations, stress\nadvantages of the Hubbard Green's function approach in constructing the rates\nand indicate that standard dressing of the diagrams is a natural way to account\nfor additional baths/degrees of freedom when formulating generalized\nexpressions for the rates.",
        "positive": "Amplicification of Voltage Controlled Magnetic Anisotropy Effect with\n  Negative Capacitance: The high current density required by Magnetic Tunneling Junction (MTJ)\nswitching driven by Spin Transfer Torque (STT) effect leads to large power\nconsumption and severe reliability issues therefore hinder the timetable for\nSTT Magnetic Random Access Memory (STT-MRAM) to mass market. By utilizing\nVoltage Controlled Magnetic Anisotropy (VCMA) effect, the MTJ can be switched\nby voltage effect and is postulated to achieve ultra-low power (fJ). However,\nthe VCMA coefficient measured in experiments is far too small for MTJ dimension\nbelow 100 nm. Here in this work, a novel approach for the amplification of VCMA\neffect which borrow ideas from negative capacitance is proposed. The\nfeasibility of the proposal is proved by physical simulation and in-depth\nanalysis."
    },
    {
        "anchor": "Terahertz detection using mechanical resonators based on 2D materials: We have investigated a THz detection scheme based on mixing of electrical\nsignals in a voltage-dependent capacitance made out of suspended graphene. We\nhave analyzed both coherent and incoherent detection regimes and compared their\nperformance with the state of the art. Using a high-amplitude local oscillator,\nwe anticipate potential for quantum limited detection in the coherent mode. The\nsensitivity stems from the extraordinary mechanical and electrical properties\nof atomically thin graphene or graphene-related 2D materials.",
        "positive": "Channel spaser: We show that net amplification of surface plasmons is achieved in channel in\na metal plate due to nonradiative excitation by quantum dots. This makes\npossible lossless plasmon transmission lines in the channel as well as the\namplification and generation of coherent surface plasmons. As an example, a\nring channel spaser is considered."
    },
    {
        "anchor": "Resonantly Tunable Majorana Polariton in a Microwave Cavity: We study the spectrum of a one-dimensional Kitaev chain placed in a microwave\ncavity. In the off-resonant regime, the frequency shift of the cavity can be\nused to identify the topological phase transition of the coupled system. In the\nresonant regime, the topology of the system can be controlled via the microwave\ncavity occupation and, moreover, for a large number of photons (classical\nlimit), the physics becomes similar to that of periodically-driven systems\n(Floquet insulators). We also analyze numerically a finite chain and show the\nexistence of a degenerate subspace in the presence of the cavity that can be\ninterpreted as a \\textit{Majorana polariton}.",
        "positive": "Quantized two terminal conductance, edge states and current patterns in\n  an open geometry 2-dimensional Chern insulator: The quantization of the two terminal conductance in 2D topological systems is\njustified by the Landauer-Buttiker (LB) theory that assumes perfect point\ncontacts between the leads and the sample. We examine this assumption in a\nmicroscopic model of a Chern insulator connected to leads, using the\nnonequilibrium Greens function formalism. We find that the currents are\nlocalized both in the leads and in the insulator and enter and exit the\ninsulator only near the corners. The contact details do not matter and a\nperfect point contact is emergent, thus justifying the LB theory. The quantized\ntwo-terminal conductance shows interesting finite-size effects and dependence\non system-reservoir coupling."
    },
    {
        "anchor": "Acoustic Frequency Multiplication and Pure Second Harmonic Generation of\n  Phonons by Magnetic Transducers: We predict frequency multiplication of surface acoustic waves in dielectric\nsubstrates via the ferromagnetic resonance of adjacent magnetic transducers\nwhen driven by microwaves. We find pure second harmonic generation (SHG)\nwithout any linear and third harmonic components by a magnetic nanowire. The\nSHG and linear phonon pumping are switched by varying the saturated\nmagnetization direction of the wire, or resolved directionally when pumped by\nmagnetic nano-disc. We address the high efficiency of SHG with comparable\nmagnitude to that of linear response, as well as unique non-reciprocal phonon\ntransport that is remarkably distinct in different phonon harmonics. Such\nacoustic frequency comb driven by microwaves should bring unprecedented\ntunability for the miniaturized phononic and spintronic devices.",
        "positive": "Heat transport through quantum Hall edge states: Tunneling versus\n  capacitive coupling to reservoirs: We study the heat transport along an edge state of a two-dimensional electron\ngas in the quantum Hall regime, in contact to two reservoirs at different\ntemperatures. We consider two exactly solvable models for the edge state\ncoupled to the reservoirs. The first one corresponds to filling $\\nu=1$ and\ntunneling coupling to the reservoirs. The second one corresponds to integer or\nfractional filling of the sequence $\\nu=1/m$ (with $m$ odd), and capacitive\ncoupling to the reservoirs. In both cases we solve the problem by means of\nnon-equilibrium Green function formalism. We show that heat propagates chirally\nalong the edge in the two setups. We identify two temperature regimes, defined\nby $\\Delta$, the mean level spacing of the edge. At low temperatures, $T<\n\\Delta$, finite size effects play an important role in heat transport, for both\ntypes of contacts. The nature of the contacts manifest themselves in different\npower laws for the thermal conductance as a function of the temperature. For\ncapacitive couplings a highly non-universal behavior takes place, through a\nprefactor that depends on the length of the edge as well as on the coupling\nstrengths and the filling fraction. For larger temperatures, $T>\\Delta$,\nfinite-size effects become irrelevant, but the heat transport strongly depends\non the strength of the edge-reservoir interactions, in both cases. The thermal\nconductance for tunneling coupling grows linearly with $T$, whereas for the\ncapacitive case it saturates to a value that depends on the coupling strengths\nand the filling factors of the edge and the contacts."
    },
    {
        "anchor": "Flat bands and topological phase transition in entangled\n  Su-Schrieffer-Heeger chains: Flat, non-dispersive bands and topological phase transition in multiple\nSu-Schrieffer-Heeger (SSH) chains, cross-linked via periodically arranged nodal\npoints are explored within a tight binding framework. We give analytic\nprescription, based on a real space decimation scheme, that extracts the energy\neigenvalues corresponding to the flat bands along with their degeneracy. The\ntopological phase transition is confirmed through the existence of quantized\nZak phase for all the Bloch bands, and the edge states that are protected by\nchiral symmetry, consistent with the bulk-boundary correspondence. In addition\nto the edge states, the entangled systems are shown to give rise to clusters of\nlocalized eigenstates in the bulk of the system, in contrast to a purely one\ndimensional SSH system.",
        "positive": "Coherent rotations of a single spin-based qubit in a single quantum dot\n  at fixed Zeeman energy: Coherent rotations of single spin-based qubits may be accomplished\nelectrically at fixed Zeeman energy with a qubit defined solely within a single\nelectrostatically-defined quantum dot; the $g$-factor and the external magnetic\nfield are kept constant. All that is required to be varied are the voltages on\nmetallic gates which effectively change the shape of the elliptic quantum dot.\nThe pseudospin-1/2 qubit is constructed from the two-dimensional $S=1/2$,\n$S_z=-1/2$ subspace of three interacting electrons in a two-dimensional\npotential well. Rotations are created by altering the direction of the\npseudomagnetic field through changes in the shape of the confinement potential.\nBy deriving an exact analytic solution to the long-range Coulomb interaction\nmatrix elements, we calculate explicitly the range of magnitudes and directions\nthe pseudomagnetic field can take. Numerical estimates are given for {GaAs}."
    },
    {
        "anchor": "Phonitons as a sound-based analogue of cavity quantum electrodynamics: A quantum mechanical superposition of a long-lived, localized phonon and a\nmatter excitation is described. We identify a realization in strained silicon:\na low-lying donor transition (P or Li) driven solely by acoustic phonons at\nwavelengths where high-Q phonon cavities can be built. This phonon-matter\nresonance is shown to enter the strongly coupled regime where the \"vacuum\" Rabi\nfrequency exceeds the spontaneous phonon emission into non-cavity modes, phonon\nleakage from the cavity, and phonon anharmonicity and scattering. We introduce\na micropillar distributed Bragg reflector Si/Ge cavity, where Q=10^5-10^6 and\nmode volumes V<=25*lambda^3 are reachable. These results indicate that single\nor many-body devices based on these systems are experimentally realizable.",
        "positive": "Canyon of Current Suppression in an interacting two-level Quantum Dot: Motivated by the recent discovery of a canyon of conductance suppression in a\ntwo-level equal spin quantum dot system [Phys. Rev. Lett. $\\bf{104}$, 186804\n(2010)] the transport through this system is studied in detail. At low bias and\nlow temperature a strong current suppression is found around the electron-hole\nsymmetry point independent of the couplings, in agreement with previous\nresults. By means of a Schrieffer-Wolff transformation we are able to give an\nintuitive explanation to this suppression in the low-energy regime. In the\ngeneral situation, numerical simulations are carried out using quantum rate\nequations. The simulations allow for the prediction of how the suppression is\naffected by the couplings, the charging energy, the position of the energy\nlevels, the applied bias, and the temperature. We find that away from\nelectron-hole symmetry, the parity of the couplings is essential for the\ncurrent suppression. It is also shown how broadening, interference, and a\nfinite interaction energy cause a shift of the current minimum away from\ndegeneracy. Finally we see how an increased population of the upper level leads\nto current peaks on each side of the suppression line. At sufficiently high\nbias we discover a coherence-induced population inversion."
    },
    {
        "anchor": "Spin filtering and entanglement detection due to spin-orbit interaction\n  in carbon nanotube cross-junctions: We demonstrate that due to their spin-orbit interaction carbon nanotube\ncross-junctions have attractive spin projective properties for transport.\nFirst, we show that the junction can be used as a versatile spin filter as a\nfunction of a backgate and a static external magnetic field. Switching between\nopposite spin filter directions can be achieved by small changes of the\nbackgate potential, and a full polarization is generically obtained in an\nenergy range close to the Dirac points. Second, we discuss how the spin\nfiltering properties affect the noise correlators of entangled electron pairs,\nwhich allows us to obtain signatures of the type of entanglement that are\ndifferent from the signatures in conventional semiconductor cross-junctions.",
        "positive": "Nonlinear carrier dynamics in a quantum dash optical amplifier: Results of experimental pump-probe spectroscopy of a quantum dash optical\namplifier biased at transparency are presented. Using strong pump pulses we\nobserve a competition between free carrier absorption and two-photon induced\nstimulated emission that can have drastic effects on the transmission dynamics.\nThus, both enhancement as well as suppression of the transmission can be\nobserved even when the amplifier is biased at transparency. A simple\ntheoretical model taking into account two-photon absorption and free carrier\nabsorption is presented that shows good agreement with the measurements."
    },
    {
        "anchor": "Theory of Charge and Heat Polarizations with the Keldysh Formalism: We investigate the heat polarization, a heat analog of the charge\npolarization, by using the gauge-covariant Keldysh formalism. In contrast to\nthe charge-heat analogy naively expected, we find that the heat polarization\ndoes not appear spontaneously, since it consists not only of the heat-transfer\ncontribution but of the heat-generation contribution, leading to the Mott rule.\nNonetheless, it can be induced by a torsional magnetic field in $(3+1)$-D\ntopological insulators and superconductors, which is described by the temporal\npart of the Nieh-Yan action.",
        "positive": "Chemical Doping and Electron-Hole Conduction Asymmetry in Graphene\n  Devices: We investigate polyethylene imine and diazonium salts as stable,\ncomplementary dopants on graphene. Transport in graphene devices doped with\nthese molecules exhibits asymmetry in electron and hole conductance. The\nconductance of one carrier is preserved, while the conductance of the other\ncarrier decreases. Simulations based on nonequilibrium Green's function\nformalism suggest that the origin of this asymmetry is imbalanced carrier\ninjection from the graphene electrodes caused by misalignment of the electrode\nand channel neutrality points."
    },
    {
        "anchor": "Mesoscopic oscillator in U-shape with giant persistent current: A mesoscopic oscillator in U-shape has been proposed and studied. Making use\nof a magnetic flux together with a potential of confinement, the electron\ncontained in the oscillator has been localized initially and an amount of\nenergy has been thereby stored. Then a sudden cancellation of both the\npotential and the flux may cause an initial current which initiates a periodic\nmotion of the electron from one end of the U-oscillator to the opposite end,\nand repeatedly. The period is adjustable. The current associated with the\nperiodic motion can be tuned very strong (say, more than two orders larger than\nthe current of the usual Aharonov-Bohm oscillation). Related theory and\nnumerical results are presented.",
        "positive": "Orbital Multiferroicity in Pentalayer Rhombohedral Graphene: Ferroic orders describe spontaneous polarization of spin, charge, and lattice\ndegrees of freedom in materials. Materials featuring multiple ferroic orders,\nknown as multiferroics, play important roles in multi-functional electrical and\nmagnetic device applications. 2D materials with honeycomb lattices offer\nexciting opportunities to engineer unconventional multiferroicity, where the\nferroic orders are driven purely by the orbital degrees of freedom but not\nelectron spin. These include ferro-valleytricity corresponding to the electron\nvalley and ferro-orbital-magnetism supported by quantum geometric effects. Such\norbital multiferroics could offer strong valley-magnetic couplings and large\nresponses to external fields-enabling device applications such as\nmultiple-state memory elements, and electric control of valley and magnetic\nstates. Here we report orbital multiferroicity in pentalayer rhombohedral\ngraphene using low temperature magneto-transport measurements. We observed\nanomalous Hall signals Rxy with an exceptionally large Hall angle (tan{\\Theta}H\n> 0.6) and orbital magnetic hysteresis at hole doping. There are four such\nstates with different valley polarizations and orbital magnetizations, forming\na valley-magnetic quartet. By sweeping the gate electric field E we observed a\nbutterfly-shaped hysteresis of Rxy connecting the quartet. This hysteresis\nindicates a ferro-valleytronic order that couples to the composite field E\\cdot\nB, but not the individual fields. Tuning E would switch each ferroic order\nindependently, and achieve non-volatile switching of them together. Our\nobservations demonstrate a new type of multiferroics and point to electrically\ntunable ultra-low power valleytronic and magnetic devices."
    },
    {
        "anchor": "Dipolar interaction and incoherent quantum tunneling: a Monte Carlo\n  study of magnetic relaxation: We study the magnetic relaxation of a system of localized spins interacting\nthrough weak dipole interactions, at a temperature large with respect to the\nordering temperature but low with respect to the crystal field level splitting.\nThe relaxation results from quantum spin tunneling but is only allowed on sites\nwhere the dipole field is very small. At low times, the magnetization decrease\nis proportional to $\\sqrt{t}$ as predicted by Prokofiev and Stamp, and at long\ntimes the relaxation can be described as an extension of a relaxed zone. The\nresults can be directly compared with very recent experimental data on Fe_8\nmolecular clusters.",
        "positive": "Far-infrared absorption of self-assembled semiconductor rings: We report a theoretical description of far-infrared spectroscopy experiments\non self-assembled quantum rings in a magnetic field [A. Lorke et al., Phys.\nRev. Lett. 84, 2223 (2000)] which, for the first time, accounts for the full\nset of experimental resonances. In our calculations we use a 3D effective-mass\nmodel with a realistic finite step-like confinement potential, including strain\nand Coulomb effects. We assume a bimodal distribution of ring sizes."
    },
    {
        "anchor": "Connective neck evolution and conductance steps in hot point contacts: Dynamic evolution of the connective neck in Al and Pb mechanically\ncontrollable break junctions was studied during continuous approach of\nelectrodes at bias voltages V_b up to a few hundred mV. A high level of power\ndissipation (10^-4 - 10^-3 W) and high current density (j > 10^10 A/cm^2) in\nthe constriction lead to overheating of the contact area, electromigration and\ncurrent-enhanced diffusion of atoms out of the \"hot spot\". At a low electrode\napproach rate (10 - 50 pm/s) the transverse dimension of the neck and the\nconductance of the junction depend on V_b and remain nearly constant over the\napproach distance of 10 - 30 nm. For V_b > 300 mV the connective neck consists\nof a few atoms only and the quantum nature of conductance manifests itself in\nabrupt steps and reversible jumps between two or more levels. These features\nare related to an ever changing number of individual conductance channels due\nto the continuous rearrangement in atomic configuration of the neck, the\nrecurring motion of atoms between metastable states, the formation and breaking\nof isolated one-atom contacts and the switching between energetically\npreferable neck geometries.",
        "positive": "Zero-bias peaks in spin-orbit coupled superconducting wires with and\n  without Majorana end-states: One of the simplest proposed experimental probes of a Majorana bound-state is\na quantized (2e^2/h) value of zero-bias tunneling conductance. When temperature\nis somewhat larger than the intrinsic width of the Majorana peak, conductance\nis no longer quantized, but a zero-bias peak can remain. Such a non-quantized\nzero-bias peak has been recently reported for semiconducting nanowires with\nproximity induced superconductivity. In this paper we analyze the relation of\nthe zero-bias peak to the presence of Majorana end-states, by simulating the\ntunneling conductance for multi-band wires with realistic amounts of disorder.\nWe show that this system generically exhibits a (non-quantized) zero-bias peak\neven when the wire is topologically trivial and does not possess Majorana\nend-states. We make comparisons to recent experiments, and discuss the\nnecessary requirements for confirming the existence of a Majorana state."
    },
    {
        "anchor": "Breakdown of the interlayer coherence in twisted bilayer graphene: Coherent motion of the electrons in the Bloch states is one of the\nfundamental concepts of the charge conduction in solid state physics. In\nlayered materials, however, such a condition often breaks down for the\ninterlayer conduction, when the interlayer coupling is significantly reduced by\ne.g. large interlayer separation. We report that complete suppression of\ncoherent conduction is realized even in an atomic length scale of layer\nseparation in twisted bilayer graphene. The interlayer resistivity of twisted\nbilayer graphene is much higher than the c-axis resistivity of Bernal-stacked\ngraphite, and exhibits strong dependence on temperature as well as on external\nelectric fields. These results suggest that the graphene layers are\nsignificantly decoupled by rotation and incoherent conduction is a main\ntransport channel between the layers of twisted bilayer graphene.",
        "positive": "Chiral vortical effect in relativistic and nonrelativistic systems: We formulate the chiral vortical effect (CVE) and its generalization called\ngeneralized vortical effect using the semiclassical theory of wave packet\ndynamics. We take the spin-vorticity coupling into account and calculate the\ntransport charge current by subtracting the magnetization one from the Noether\nlocal one. We find that the transport charge current in the CVE always vanishes\nin relativistic chiral fermions. This result implies that it cannot be observed\nin transport experiments in condensed matter systems such as Dirac/Weyl\nsemimetals with the pseudo-Lorentz symmetry. We also demonstrate that the\nanisotropic CVE can be observed in nonrelativistic systems that belong to the\npoint groups $D_n, C_n (n = 2, 3, 4, 6)$, and $C_1$, such as $n$-type\ntellurium."
    },
    {
        "anchor": "Coulomb-blockade effect in nonlinear mesoscopic capacitors: We consider an interacting quantum dot working as a coherent source of single\nelectrons. The dot is tunnel coupled to a reservoir and capacitively coupled to\na gate terminal with an applied ac potential. At low frequencies, this is the\nquantum analog of the RC circuit with a purely dynamical response. We\ninvestigate the quantized dynamics as a consequence of ac pulses with large\namplitude. Within a Keldysh-Green function formalism we derive the\ntime-dependent current in the Coulomb blockade regime. Our theory thus extends\nprevious models that considered either noninteracting electrons in nonlinear\nresponse or interacting electrons in the linear regime. We prove that the\nelectron emission and absorption resonances undergo a splitting when the\ncharging energy is larger than the tunnel broadening. For very large charging\nenergies, the additional peaks collapse and the original resonances are\nrecovered, though with a reduced amplitude. Quantization of the charge emitted\nby the capacitor is reduced due to Coulomb repulsion and additional plateaus\narise. Additionally, we discuss the differential capacitance and resistance as\na function of time. We find that to leading order in driving frequency the\ncurrent can be expressed as a weighted sum of noninteracting currents shifted\nby the charging energy.",
        "positive": "Screening, nonadiabaticity, and quantized acoustoelectric current: Quantized single-electron transport driven by surface acoustic waves (SAW)\nthrough a pinched-off narrow constriction is studied theoretically. Long-range\nCoulomb interaction causes the tunneling coupling between the two-dimensional\nelectron gas (2DEG) and the moving minimum of the SAW-induced potential to\ndecay rapidly with time. The energy scale, associated with the characteristic\ntime of this decay, controls both the width of the transition regions between\nthe plateaus and the slope of the plateaus. This sets a limit for the accuracy\nof the quantization of acoustoelectric current at low temperature."
    },
    {
        "anchor": "Complete escape from localization on a hierarchical lattice: A Koch\n  fractal with all states extended: An infinitely large Koch fractal is shown to be capable of sustaining only\nextended, Bloch-like eigenstates, if certain parameters of the Hamiltonian\ndescribing the lattice are numerically correlated in a special way, and a\nmagnetic flux of a special strength is trapped in every loop of the geometry.\nWe describe the system within a tight binding formalism and prescribe the\ndesired correlation between the numerical values of the nearest neighbor\noverlap integrals, along with a special value of the magnetic flux trapped in\nthe triangular loops decorating the fractal. With such conditions, the lattice,\ndespite the absence of translational order of any kind whatsoever, yields an\nabsolutely continuous eigenvalue spectrum, and becomes completely transparent\nto an incoming electron with any energy within the allowed band. The results\nare analytically exact. An in-depth numerical study of the inverse\nparticipation ratio and the two-terminal transmission coefficient corroborates\nour findings. Our conclusions remain valid for a large set of lattice models,\nbuilt with the same structural units, but beyond the specific geometry of a\nKoch fractal, unraveling a subtle universality in a variety of such low\ndimensional systems.",
        "positive": "Bulk-boundary-transport correspondence of the second-order topological\n  insulators: The bulk-boundary correspondence of the second-order topological insulator\n(SOTI) has been well established, but a universal transport signature for open\nsystems is still absent. For a variety of SOTIs induced by applying in-plane\nmagnetic fields in Z$_2$-invariant first-order TIs, rotating this magnetic\nfield features the spin pump mechanism while maintaining the SOTI phase. We\ndemonstrate that, this spin pump can generate quantized pure spin current when\ntuning the magnetic field strength, which corresponds to the formation of\ntopological corner states characterizing SOTI in two-dimensional (2D) systems.\nQuantized spin pump is discovered in various 2D and 3D SOTI models evolved from\nZ$_2$-invariant TIs, which is robust against disorder and universally\nindependent of system parameters including Fermi energy, system size, magnetic\nfield strength, and pumping frequency. These findings suggest that this\nuniversal quantized spin pump can characterize the bulk-boundary-transport\ncorrespondence of SOTIs. Quantized spin pump can also be realized by combining\npseudo spin such as the orbital degree of freedom with the rotating magnetic\nfield, which could be achieved in higher-order photonic or acoustic topological\nsystems. Such a quantized spin pump is promising as an accurate and stable\nsingle-spin source."
    },
    {
        "anchor": "Guiding center picture of magnetoresistance oscillations in rectangular\n  superlattices: We calculate the magneto-resistivities of a two-dimensional electron gas\nsubjected to a lateral superlattice (LSL) of rectangular symmetry within the\nguiding-center picture, which approximates the classical electron motion as a\nrapid cyclotron motion around a slowly drifting guiding center. We explicitly\nevaluate the velocity auto-correlation function along the trajectories of the\nguiding centers, which are equipotentials of a magnetic-field dependent\neffective LSL potential. The existence of closed equipotentials may lead to a\nsuppression of the commensurability oscillations, if the mean free path and the\nLSL modulation potential are large enough. We present numerical and analytical\nresults for this suppression, which allow, in contrast to previous quantum\narguments, a classical explanation of similar suppression effects observed\nexperimentally on square-symmetric LSL. Furthermore, for rectangular LSLs of\nlower symmetry they lead us to predict a strongly anisotropic resistance\ntensor, with high- and low-resistance directions which can be interchanged by\ntuning the externally applied magnetic field.",
        "positive": "Enhanced Spin Conductance of a Thin-Film Insulating Antiferromagnet: We investigate spin transport by thermally excited spin waves in an\nantiferromagnetic insulator. Starting from a stochastic Landau-Lifshitz-Gilbert\nphenomenology, we obtain the out-of-equilibrium spin-wave properties. In linear\nresponse to spin biasing and a temperature gradient, we compute the spin\ntransport through a normal metal$|$antiferromagnet$|$normal metal\nheterostructure. We show that the spin conductance diverges as one approaches\nthe spin-flop transition; this enhancement of the conductance should be readily\nobservable by sweeping the magnetic field across the spin-flop transition. The\nresults from such experiments may, on the one hand, enhance our understanding\nof spin transport near a phase transition, and on the other be useful for\napplications that require a large degree of tunability of spin currents. In\ncontrast, the spin Seebeck coefficient does not diverge at the spin-flop\ntransition. Furthermore, the spin Seebeck coefficient is finite even at zero\nmagnetic field, provided that the normal metal contacts break the symmetry\nbetween the antiferromagnetic sublattices."
    },
    {
        "anchor": "Monolithically integrated single quantum dots coupled to bowtie\n  nanoantennas: Deterministically integrating semiconductor quantum emitters with plasmonic\nnano-devices paves the way towards chip-scale integrable, true nanoscale\nquantum photonics technologies. For this purpose, stable and bright\nsemiconductor emitters are needed, which moreover allow for CMOS-compatibility\nand optical activity in the telecommunication band. Here, we demonstrate\nstrongly enhanced light-matter coupling of single near-surface ($<10\\,nm$) InAs\nquantum dots monolithically integrated into electromagnetic hot-spots of\nsub-wavelength sized metal nanoantennas. The antenna strongly enhances the\nemission intensity of single quantum dots by up to $\\sim16\\times$, an effect\naccompanied by an up to $3.4\\times$ Purcell-enhanced spontaneous emission rate.\nMoreover, the emission is strongly polarised along the antenna axis with\ndegrees of linear polarisation up to $\\sim85\\,\\%$. The results unambiguously\ndemonstrate the efficient coupling of individual quantum dots to\nstate-of-the-art nanoantennas. Our work provides new perspectives for the\nrealisation of quantum plasmonic sensors, step-changing photovoltaic devices,\nbright and ultrafast quantum light sources and efficent nano-lasers.",
        "positive": "Reply to comment (arXiv:0907.2026v2) on \"Consistent Interpretation of\n  the Low-Temperature Magnetotransport in Graphite Using the\n  Slonczewski-Weiss-McClure 3D Band-Structure Calculations\" (arXiv:0902.1925): Reply to comment (arXiv:0907.2026v2) on \"Consistent Interpretation of the\nLow-Temperature Magnetotransport in Graphite Using the\nSlonczewski-Weiss-McClure 3D Band-Structure Calculations\" (arXiv:0902.1925)"
    },
    {
        "anchor": "Bias induced spin state transition mediated by electron excitations: Recent experiments reported that spin-state transitions were realized by\napplying bias voltages. But these bias-induced spin state transitions (BISSTs)\nare not fully understood, especially the mechanism. It is well known that the\nmetal-to-ligand charge transfer excitation (MLCT) and the metal-centered\nexcitation (MC) activated by light radiation can induce the transition from low\nspin (LS) to high spin (HS) and that from HS to LS. Moreover, electronic\nexcitations are accessible by inelastic cotunneling in molecular junctions with\nbias voltages applied. Based on these two experimental facts, we propose the\nMLCT basically leads to the BISST from LS to HS, and the MC results in the\nBISST from HS to LS. The rationality of the mechanism is demonstrated by\ncomparing first-principles results and experimental observations. The\ncalculated voltage threshold for activating the MLCT (MC) is close to the\nexperimental voltage for observing the BISST from LS to HS (from HS to LS). The\nactivation of MLCT (MC) depends on the bias polarity, which can explain the\nbias-polarity dependence of BISST in the experiment. Our study is important for\nfurther design of molecular spintronic devices working on spin state\ntransition.",
        "positive": "Excitation spectrum of two correlated electrons in a lateral quantum dot\n  with negligible Zeeman splitting: The excitation spectrum of a two-electron quantum dot is investigated by\ntunneling spectroscopy in conjuction with theoretical calculations. The dot\nmade from a material with negligible Zeeman splitting has a moderate spatial\nanisotropy leading to a splitting of the two lowest triplet states at zero\nmagnetic field. In addition to the well-known triplet excitation at zero\nmagnetic field, two additional excited states are found at finite magnetic\nfield. The lower one is identified as the second excited singlet state on the\nbasis of an avoided crossing with the first excited singlet state at finite\nfields. The measured spectra are in remarkable agreement with exact\ndiagonalization calculations. The results prove the significance of electron\ncorrelations and suggest the formation of a state with Wigner-molecular\nproperties at low magnetic fields."
    },
    {
        "anchor": "Double flat bands in kagome twisted bilayers: We have studied how a generic bilayer kagome lattice behave upon layer\nrotation. We employed a Tight Binding model with one orbital per site and found\n(i) for low rotational angles, and at low energies, the same flat bands\nstructure like in twisted bilayer graphene; though, for a larger value of the\nmagic angle. Moreover, (ii) at high energies, due to the superstructure\nsymmetry regions, we found the characteristics three band dispersion of the\nkagome lattice. In the latter, its band width decreases for lower angles\nconfining them within a few meV. Therefore, we found in twisted kagome lattice\nthe coexistence of two sets of flat bands in different energies and lying in\ndifferent spatial regions of the bilayer system.",
        "positive": "Localization transition on complex networks via spectral statistics: The spectral statistics of complex networks are numerically studied.\n  The features of the Anderson metal-insulator transition are found to be\nsimilar for a wide range of different networks. A metal-insulator transition as\na function of the disorder can be observed for different classes of complex\nnetworks for which the average connectivity is small. The critical index of the\ntransition corresponds to the mean field expectation. When the connectivity is\nhigher, the amount of disorder needed to reach a certain degree of localization\nis proportional to the average connectivity, though a precise transition cannot\nbe identified. The absence of a clear transition at high connectivity is\nprobably due to the very compact structure of the highly connected networks,\nresulting in a small diameter even for a large number of sites."
    },
    {
        "anchor": "Reliably Counting Atomic Planes of Few-Layer Graphene (n>4): We demonstrate a reliable technique for counting atomic planes (n) of\nfew-layer graphene (FLG) on SiO2/Si substrates by Raman spectroscopy. Our\napproach is based on measuring the ratio of the integrated intensity of the G\ngraphene peak and the optical phonon peak of Si, I(G)/I(Si), and is\nparticularly useful in the range n>4 where few methods exist. We compare our\nresults with atomic force microscopy (AFM) measurements and Fresnel equation\ncalculations. Lastly, we apply our method to unambiguously identify n of FLG\ndevices and find that the mobility (~2000 cm2 V-1 s-1) is independent of layer\nthickness for n>4.",
        "positive": "On the geometry of carbon nanostructures formed at reaction of organic\n  compounds at high pressure and temperature: Based on the analysis of the data on the behavior of electric conductivity at\nthe detonation of condensed high explosives (HEs) with the composition CHNO and\nthe carbon mass fraction higher than 0.1, the conclusion was made of the\npresence of long carbon nanostructures. These structures penetrate all the\nspace of reacting HE. The structures are formed already in the chemical peak\nregion, and they evolve along the detonation wave."
    },
    {
        "anchor": "Gate controlled Majorana Zero Modes on 2D heterostructures: Half-integer conductance, the signature of Majorana edge modes, has been\nrecently observed in a quantum anomalous Hall insulator/superconductor\nheterostructure. Here, we analyze a scheme for gate-tunable control of\ndegenerate ground states of Majorana zero modes (MZM) in thin film topological\nsuperconductors. Gating the top surface of a thin film magnetic topological\ninsulator controls the topological phase in the region underneath the gate. The\nvoltage of the transition depends on the gate width, and narrower gates require\nlarger voltages. Relatively long gates are required, on the order of a micron,\nto prevent hybridization of the end modes and to allow the creation of MZMs at\nlow gate voltages. Applying a voltage to T{shaped and I{shaped gates localizes\nthe Majoranas at their ends. This scheme may provide a facile method for\nimplementing quantum gates for topological quantum computing.",
        "positive": "Quantum pumping and dissipation in closed systems: Current can be pumped through a closed system by changing parameters (or\nfields) in time. Linear response theory (the Kubo formula) allows to analyze\nboth the charge transport and the associated dissipation effect. We make a\ndistinction between adiabatic and non-adiabatic regimes, and explain the subtle\nlimit of an infinite system. As an example we discuss the following question:\nWhat is the amount of charge which is pushed by a moving scatterer? In the low\nfrequency (DC) limit we can write dQ=-GdX, where dX is the displacement of the\nscatterer. Thus the issue is to calculate the generalized conductance $G$."
    },
    {
        "anchor": "Thermopower in Andreev interferometers: We examine the thermopower Q of a mesoscopic normal-metal (N) wire in contact\nto superconducting (S) segments and show that even with electron-hole symmetry,\nQ may become finite due to the presence of supercurrents. Moreover, we show how\nthe dominant part of Q can be directly related to the equilibrium supercurrents\nin the structure. We also discuss the thermopower arising due to an anomalous\nkinetic coefficient which is finite in the presence of supercurrent and in some\nsituations gives the dominant contribution. In general, a finite thermopower\nappears both between the N reservoirs and the superconductors, and between the\nN reservoirs themselves. The latter, however, strongly depends on the\ngeometrical symmetry of the structure. The paper includes a detailed analytical\nderivation of the results and an exact numerical solution of the quasiclassical\nequations in a few sample geometries.",
        "positive": "Single and double ultrashort laser pulse scattering by spheroidal\n  metallic nanoparticles: The theory of the ultrashort laser pulse scattered by metallic nanoparticles\nin the region of surface plasmon resonances is developed in the framework of\nkinetic approach. For the spheroidal particles, the dependence of the light\nscattering cross-section on the shape of the particles, the carrier wave\nfrequency, a pulse duration, and other factors is studied. Additionally, an\ninteraction of small metallic particles with double ultrashort pulse is\nconsidered. In this case, the energy scattered by the particles demonstrates\noscillating behavior when the time delay between pulses changes. Special\nattention is paid to the contribution of the particle's surface when the\nparticle's size is close to the length of free electron path. The difference\nbetween the kinetic approach and Mie theory for non-spherical particles has\nbeen shown."
    },
    {
        "anchor": "Presence of asymmetric noise in multi-terminal chaotic cavities: This work deals with chaotic quantum dot connected to two and four leads. We\nuse standard diagrammatic procedure to integrate on the unitary group, to study\nthe main term in the semiclassical expansion of the noise in the three pure\nWigner-Dyson ensembles at finite frequency and temperature, in the\nnoninteracting and interacting regimes. We investigate several limits, related\nto the temperature and the potential difference in the leads, in the presence\nof a capacitive environment. At the thermal crossover regime, we obtain general\nexpressions described in terms of parameters that can be controlled\nexperimentally. As an interesting result, we show the appearance of asymmetries\nin the noise, controlled by the topology of the cavity and the number of open\nchannels in the corresponding terminals.",
        "positive": "Fermi velocity engineering in graphene by substrate modification: The Fermi velocity is one of the key concepts in the study of a material, as\nit bears information on a variety of fundamental properties. Upon increasing\ndemand on the device applications, graphene is viewed as a prototypical system\nfor engineering Fermi velocity. Indeed, several efforts have succeeded in\nmodifying Fermi velocity by varying charge carrier concentration. Here we\npresent a powerful but simple new way to engineer Fermi velocity while holding\nthe charge carrier concentration constant. We find that when the environment\nembedding graphene is modified, the Fermi velocity of graphene is (i) inversely\nproportional to its dielectric constant, reaching ~2.5$\\times10^6$ m/s, the\nhighest value for graphene on any substrate studied so far and (ii) clearly\ndistinguished from an ordinary Fermi liquid. The method demonstrated here\nprovides a new route toward Fermi velocity engineering in a variety of\ntwo-dimensional electron systems including topological insulators."
    },
    {
        "anchor": "Structural correlations and dependent scattering mechanism on the\n  radiative properties of random media: The dependent scattering mechanism is known to have a significant impact on\nthe radiative properties of random media containing discrete scatterers. Here\nwe theoretically demonstrate the role of dependent scattering on the radiative\nproperties of disordered media composed of nonabsorbing, dual-dipolar\nparticles. Based on our theoretical formulas for the radiative properties for\nsuch media, we investigate the dependent scattering effects, including the\neffect of modification of the electric and magnetic dipole excitations and the\nfar-field interference effect, both induced and influenced by the structural\ncorrelations. We study in detail how the structural correlations play a role in\nthe dependent scattering mechanism by using two types of particle system, i.e.,\nthe hard-sphere system and the sticky-hard-sphere system. We show that the\ninverse stickiness parameter, which controls the interparticle adhesive force\nand thus the particle correlations, can tune the radiative properties\nsignificantly. Particularly, increasing the surface stickiness can result in a\nhigher scattering coefficient and a larger asymmetry factor. The results also\nimply that in the present system, the far-field interference effect plays a\ndominant role in the radiative properties while the effect of modification of\nthe electric and magnetic dipole excitations is more subtle. Our study is\npromising in understanding and manipulating the radiative properties of\ndual-dipolar random media.",
        "positive": "Valley coupling in finite-length metallic single-wall carbon nanotubes: Degeneracy of discrete energy levels of finite-length, metallic single-wall\ncarbon nanotubes depends on type of nanotubes, boundary condition, length of\nnanotubes and spin-orbit interaction. Metal-1 nanotubes, in which two\nnon-equivalent valleys in the Brillouin zone have different orbital angular\nmomenta with respect to the tube axis, exhibits nearly fourfold degeneracy and\nsmall lift of the degeneracy by the spin-orbit interaction reflecting the\ndecoupling of two valleys in the eigenfunctions. In metal-2 nanotubes, in which\nthe two valleys have the same orbital angular momentum, vernier-scale-like\nspectra appear for boundaries of orthogonal-shaped edge or cap-termination\nreflecting the strong valley coupling and the asymmetric velocities of the\nDirac states. Lift of the fourfold degeneracy by parity splitting overcomes the\nspin-orbit interaction in shorter nanotubes with a so-called minimal boundary.\nSlowly decaying evanescent modes appear in the energy gap induced by the\ncurvature of nanotube surface. Effective one-dimensional model reveals the role\nof boundary on the valley coupling in the eigenfunctions."
    },
    {
        "anchor": "Nonsymmorphic chiral symmetry and solitons in the Rice-Mele model: The Rice-Mele model has two topological and spatially-inversion symmetric\nphases, namely the Su-Schrieffer-Heeger (SSH) phase with alternating hopping\nonly, and the charge-density-wave (CDW) phase with alternating energies only.\nThe chiral symmetry of the SSH phase is robust in position space, so that it is\npreserved in the presence of the ends of a finite system and of textures in the\nalternating hopping. However, the chiral symmetry of the CDW wave phase is\nnonsymmorphic, resulting in a breaking of the bulk topology by an end or a\ntexture in the alternating energies. We consider the presence of solitons\n(textures in position space separating two degenerate ground states) in finite\nsystems with open boundary conditions. We identify the parameter range under\nwhich an atomically-sharp soliton in the CDW phase supports a localized state\nwhich lies within the band gap, and we calculate the expectation value $p_y$ of\nthe nonsymmorphic chiral operator for this state, and the soliton electric\ncharge. As the spatial extent of the soliton increases beyond the atomic limit,\nthe energy level approaches zero exponentially quickly or inversely\nproportionally to the width, depending on microscopic details of the soliton\ntexture. In both cases, the difference of $p_y$ from one is inversely\nproportional to the soliton width, while the charge is independent of the\nwidth. We investigate the robustness of the soliton level in the presence of\ndisorder and sample-to-sample parameter variations, comparing with a single\nsoliton level in the SSH phase with an odd number of sites.",
        "positive": "Dark channels in resonant tunneling transport through artificial atoms: We investigate sequential tunneling through a multilevel quantum dot\nconfining multiple electrons, in the regime where several channels are\navailable for transport within the bias window. By analyzing solutions to the\nmaster equations of the reduced density matrix, we give general conditions on\nwhen the presence of a second transport channel in the bias window quenches\ntransport through the quantum dot. These conditions are in terms of distinct\ntunneling anisotropies which may aid in explaining the occurrence of negative\ndifferential conductance in quantum dots in the nonlinear regime."
    },
    {
        "anchor": "Metastability and dynamics in remanent states of square artificial spin\n  ice with long-range dipole interactions: After removal of an applied magnetic field, artificial square spin ice can be\nleft in a metastable remanent state, with nonzero residual magnetization and\nexcess energy above the ground state. Using a model of magnetic islands with\ndipoles of fixed magnitude and local anisotropies, the remanent states are\nprecisely determined here, including all long-range dipole interactions. Small\ndeviations away from remanent states are analyzed and the frequencies of modes\nof oscillation are determined. Some modes reach zero frequency at high symmetry\nwave vectors, such that the stability limits are found, as determined by the\nlocal anisotropy strength relative to the dipolar coupling strength.",
        "positive": "Voltage Controlled Magnetic Anisotropy Based Low Energy Switching of a\n  Ferromagnet on a Topological Insulator: We present a novel memory device that consists of a thin ferromagnetic layer\nof Fe deposited on topological insulator thin film, Bi2Se3. The ferromagnetic\nlayer has perpendicular anisotropy, due to MgO deposited on the top surface of\nFe. When current is passed on the surface of Bi2Se3, the surface of the Bi2Se3\nbecomes spin polarized and strong exchange interaction occurs between the d\nelectrons in the ferromagnet and the electrons conducting the current on the\nsurface of the Bi2Se3. Part of the current is shunted through the ferromagnet\nwhich generates spin transfer torque in the ferromagnet. The combination of the\nspin transfer torque and exchange interaction torque along with\nvoltage-controlled magnetic anisotropy (VCMA) allows ultralow-energy switching\nof the ferromagnet. We perform micromagnetic simulations and predict switching\ntime of the order of 2.5 ns and switching energy of the order of 0.45fJ for a\nferromagnetic bit with thermal stability of 43kBT. Such ultralow-energy and\nhigh-speed VCMA-induced switching of a perpendicular anisotropy ferromagnet on\na topological insulator could be utilized for energy-efficient memory design."
    },
    {
        "anchor": "Dynamic localization versus photon-assisted transport in semiconductor\n  superlattices driven by dc-ac fields: Via the numerical analysis on the intraband dynamics of optically excited\nsemiconductor superlattices, we find that time-integrated squared THz emission\nsignals can be used for probing both dynamic localization and multi-photon\nresonance in the coherent regime. Competition effect between dynamic\nlocalization and photon-assisted transport has also been discussed.",
        "positive": "Quantum return probability of a system of $N$ non-interacting lattice\n  fermions: We consider $N$ non-interacting fermions performing continuous-time quantum\nwalks on a one-dimensional lattice. The system is launched from a most compact\nconfiguration where the fermions occupy neighboring sites. We calculate exactly\nthe quantum return probability (sometimes referred to as the Loschmidt echo) of\nobserving the very same compact state at a later time $t$. Remarkably, this\nprobability depends on the parity of the fermion number -- it decays as a power\nof time for even $N$, while for odd $N$ it exhibits periodic oscillations\nmodulated by a decaying power law. The exponent also slightly depends on the\nparity of $N$, and is roughly twice smaller than what it would be in the\ncontinuum limit. We also consider the same problem, and obtain similar results,\nin the presence of an impenetrable wall at the origin constraining the\nparticles to remain on the positive half-line. We derive closed-form\nexpressions for the amplitudes of the power-law decay of the return probability\nin all cases. The key point in the derivation is the use of Mehta integrals,\nwhich are limiting cases of the Selberg integral."
    },
    {
        "anchor": "Precise quantization of anomalous Hall effect near zero magnetic field: We report a nearly ideal quantum anomalous Hall effect in a three-dimensional\ntopological insulator thin film with ferromagnetic doping. Near zero applied\nmagnetic field we measure exact quantization in Hall resistance to within a\npart per 10,000 and longitudinal resistivity under 1 ohm per square, with\nchiral edge transport explicitly confirmed by non-local measurements.\nDeviations from this behavior are found to be caused by thermally-activated\ncarriers, which can be eliminated by taking advantage of an unexpected\nmagnetocaloric effect.",
        "positive": "Microwave spectroscopy of spin-orbit coupled states: energy detuning\n  versus interdot coupling modulation: We study the AC field induced current peaks of a spin blockaded double\nquantum dot with spin-orbit interaction. The AC field modulates either the\ninterdot tunnel coupling or the energy detuning, and we choose the AC field\nfrequency range to induce two singlet-triplet transitions giving rise to two\ncurrent peaks. We show that for a large detuning the two current peaks can be\nsignificantly stronger when the AC field modulates the tunnel coupling, thus\nmaking the detection of the spin-orbit gap more efficient. We also demonstrate\nthe importance of the time dependence of the spin-orbit interaction."
    },
    {
        "anchor": "Temperature dependence of the emission linewidth in MgO-based spin\n  torque nano-oscillators: Spin transfer driven excitations in magnetic nanostructures are characterized\nby a relatively large microwave emission linewidth (10 -100 MHz). Here we\ninvestigate the role of thermal fluctuations as well as of the non-linear\namplitude-phase coupling parameter and the amplitude relaxation rate to explain\nthe linewidth broadening of in-plane precession modes induced in planar\nnanostructures. Experiments on the linewidth broadening performed on MgO based\nmagnetic tunnel junctions are compared to the linewidth obtained from macrospin\nsimulations and from evaluation of the phase variance. In all cases we find\nthat the linewidth varies linearly with temperature when the amplitude\nrelaxation rate is of the same order as the linewidth and when the\namplitude-phase coupling parameter is relatively small. The small\namplitude-phase coupling parameter means that the linewidth is dominated by\ndirect phase fluctuations and not by amplitude fluctuations, explaining thus\nits linear dependence as a function of temperature.",
        "positive": "Charge Kondo circuit as a detector for electron-electron interactions in\n  a Luttinger Liquid: We investigate the effects of the electron-electron interactions on the\nquantum transport through a charge Kondo circuit. The setup consists of a\nquantum dot sandwiched between two leads by two nearly transparent single mode\nquantum point contacts. The size of the interacting area $L$ in the Luttinger\nliquid formed in the vicinities of the narrow constrictions is assumed to be\nmuch smaller compared to the size of the quantum dot $a$. We predict that the\ninterplay between the electron-electron interactions in the Luttinger liquid\nand the fingerprints of the non-Fermi liquid behavior in the vicinity of the\ntwo channel Kondo intermediate coupling fixed point allows one to determine the\ninteraction strength through the power-law temperature scaling of the electric\nconductance."
    },
    {
        "anchor": "Extremely low energy ARPES of quantum well states in cubic-GaN/AlN and\n  GaAs/GaAlAs heterostructures: Quantum well (QW) heterostructures have been extensively used for the\nrealization of a wide range of optical and electronic devices. Exploiting their\npotential for further improvement and development requires a fundamental\nunderstanding of their electronic structure. So far, the most commonly used\nexperimental techniques for this purpose have been all-optical spectroscopy\nmethods that, however, are generally averaged in momentum space. Additional\ninformation can be gained by angle-resolved photoelectron spectroscopy (ARPES),\nwhich measures the electronic structure with momentum resolution. Here we\nreport on the use of extremely low energy ARPES (photon energy $\\sim$ 7 eV) to\nincrease its depth sensitivity and access buried QW states, located at 3 nm and\n6 nm below the surface of cubic-GaN/AlN and GaAs/AlGaAs heterostructures,\nrespectively. We find that the QW states in cubic-GaN/AlN can indeed be\nobserved, but not their energy dispersion because of the high surface\nroughness. The GaAs/AlGaAs QW states, on the other hand, are buried too deep to\nbe detected by extremely low energy ARPES. Since the sample surface is much\nflatter, the ARPES spectra of the GaAs/AlGaAs show distinct features in\nmomentum space, which can be reconducted to the band structure of the topmost\nsurface layer of the QW structure. Our results provide important information\nabout the samples' properties required to perform extremely low energy ARPES\nexperiments on electronic states buried in semiconductor heterostructures.",
        "positive": "Nonlinear resonance in a three-terminal carbon nanotube resonator: The RF-response of a three-terminal carbon nanotube resonator coupled to\nRF-transmission lines is studied by means of perturbation theory and direct\nnumerical integration. We find three distinct oscillatory regimes, including\none regime capable of exhibiting very large hysteresis loops in the frequency\nresponse. Considering a purely capacitive transduction, we derive a set of\nalgebraic equations which can be used to find the output power (S-parameters)\nfor a device connected to transmission lines with characteristic impedance\n$Z_0$."
    },
    {
        "anchor": "What Can We Learn from Noise? -- Mesoscopic Nonequilibrium Statistical\n  Physics --: Mesoscopic systems -- small electric circuits working in quantum regime --\noffer us a unique experimental stage to explorer quantum transport in a tunable\nand precise way. The purpose of this Review is to show how they can contribute\nto statistical physics. We introduce the significance of fluctuation, or\nequivalently noise, as noise measurement enables us to address the fundamental\naspects of a physical system. The significance of the fluctuation theorem (FT)\nin statistical physics is noted. We explain what information can be deduced\nfrom the current noise measurement in mesoscopic systems. As an important\napplication of the noise measurement to statistical physics, we describe our\nexperimental work on the current and current noise in an electron\ninterferometer, which is the first experimental test of FT in quantum regime.\nOur attempt will shed new light in the research field of mesoscopic quantum\nstatistical physics.",
        "positive": "Filtering of spin currents based on ballistic ring: Quantum interference effects in rings provide suitable means for controlling\nspin at mesoscopic scales. Here we apply such a control mechanism to the\nspin-dependent transport in a ballistic quasi one dimensional ring patterned in\ntwo dimensional electron gases (2DEGs). The study is essentially based on the\n{\\it natural} spin-orbit (SO) interactions, one arising from the laterally\nconfining electric field {($\\beta$ term) and the other due to to the\nquantum-well potential that confines electrons in the 2DEG (conventional Rashba\nSO interaction or $\\alpha$ term).} We focus on single-channel transport and\nsolve analytically the spin polarization of the current. As an important\nconsequence of the presence of spin splitting, we find the occurrence of spin\ndependent current oscillations.\n  We analyze %the effects of disorder by discussing the transport in the\npresence of one non-magnetic obstacle in the ring. We demonstrate that a spin\npolarized current can be induced when an unpolarized charge current is injected\nin the ring, by focusing on the central role that the presence of the obstacle\nplays."
    },
    {
        "anchor": "Interaction-induced shift of the cyclotron resonance of graphene using\n  infrared spectroscopy: We report a study of the cyclotron resonance (CR) transitions to and from the\nunusual $n=0$ Landau level (LL) in monolayer graphene. Unexpectedly, we find\nthe CR transition energy exhibits large (up to 10%) and non-monotonic shifts as\na function of the LL filling factor, with the energy being largest at\nhalf-filling of the $n=0$ level. The magnitude of these shifts, and their\nmagnetic field dependence, suggests that an interaction-enhanced energy gap\nopens in the $n=0$ level at high magnetic fields. Such interaction effects\nnormally have limited impact on the CR due to Kohn's theorem [W. Kohn, Phys.\nRev. {\\bf 123}, 1242 (1961)], which does not apply in graphene as a consequence\nof the underlying linear band structure.",
        "positive": "Chiral-induced unidirectional spin-to-charge conversion: The observation of spin-dependent transmission of electrons through chiral\nmolecules has led to the discovery of chiral-induced spin selectivity (CISS).\nThe remarkably high efficiency of the spin polarizing effect has recently\ngained significant interest due to the high potential for novel sustainable\nhybrid chiral molecule magnetic applications. However, the fundamental\nmechanisms underlying the chiral-induced phenomena remain to be understood\nfully. In this work, we explore the impact of chirality on spin angular\nmomentum in hybrid metal/ chiral molecule thin film heterostructures. For this,\nwe inject a pure spin current via spin pumping and investigate the\nspin-to-charge conversion at the hybrid chiral interface. Notably, we observe a\nchiral-induced unidirectionality in the conversion. Furthermore,\nangle-dependent measurements reveal that the spin selectivity is maximum when\nthe spin angular momentum is aligned with the molecular chiral axis. Our\nfindings validate the central role of spin angular momentum for the CISS\neffect, paving the path toward three-dimensional functionalization of hybrid\nmolecule-metal devices via chirality."
    },
    {
        "anchor": "Characterization of dynamical regimes and entanglement sudden death in a\n  microcavity quantum - dot system: The relation between the dynamical regimes (weak and strong coupling) and\nentanglement for a dissipative quantum - dot microcavity system is studied. In\nthe framework of a phenomenological temperature model an analysis in both,\ntemporal (population dynamics) and frequency domain (photoluminescence) is\ncarried out in order to identify the associated dynamical behavior. The Wigner\nfunction and concurrence are employed to quantify the entanglement in each\nregime. We find that sudden death of entanglement is a typical characteristic\nof the strong coupling regime.",
        "positive": "Origin of subgap states in normal-insulator-superconductor van der Waals\n  heterostructures: Superconductivity in van der Waals materials, such as NbSe$_{2}$ and\nTaS$_{2}$, is fundamentally novel due to the effects of dimensionality, crystal\nsymmetries, and strong spin-orbit coupling. In this work we perform tunnel\nspectroscopy on NbSe$_{2}$ by utilizing MoS$_{2}$ or hexagonal Boron Nitride\n(hBN) as a tunnel barrier. We observe subgap excitations and probe their origin\nby studying various heterostructure designs. We show that the edge of\nNbSe$_{2}$ hosts many defect states, which strongly couple to the\nsuperconductor and form Andreev bound states. Furthermore, by isolating the\nNbSe$_{2}$ edge we show that the subgap states are ubiquitous in MoS$_{2}$\ntunnel barriers, but absent in hBN tunnel barriers, suggesting defects in\nMoS$_{2}$ as their origin. Their magnetic nature reveals a singlet or a doublet\ntype ground state and based on nearly vanishing g-factors or avoided-crossing\nof subgap excitations we highlight the role of strong spin-orbit coupling."
    },
    {
        "anchor": "Alkali doping of graphene: the crucial role of high temperature\n  annealing: The doping efficiency of lithium deposited at cryogenic temperatures on\nepitaxial and CVD monolayer graphene has been investigated under ultra-high\nvacuum conditions. Change of charge carrier density was monitored by gate\nvoltage shift of the Dirac point and by Hall measurements, in low and high\ndoping regimes. It was found that pre-annealing the graphene greatly enhanced\nthe maximum levels of doping that could be achieved: doping saturated at\n$\\Delta n = 2\\times 10^{13}$ e$^-$/cm$^2$ without annealing, independent of\nsample type or previous processing; after a 900 K anneal, the saturated doping\nrose one order of magnitude to $\\Delta n = 2\\times 10^{14}$ e$^-$/cm$^2$.",
        "positive": "Kondo and mixed valence regimes in multi-level quantum dots: We investigate the dependence of the ground state of a multi-level quantum\ndot on the coupling to an external fermionic system and on the interactions in\nthe dot. As the coupling to the external system increases, the rearrangement of\nthe effective energy levels in the dot signals the transition from the Kondo\nregime to a mixed valence (MV) regime. The MV regime in a two level dot is\ncharacterized by an intrinsic mixing of the levels in the dot, resulting in\nnon-perturbative sub- and super-tunneling phenomena that strongly influence the\nKondo effect."
    },
    {
        "anchor": "Realistic micromagnetic description of all-optical ultrafast switching\n  processes in ferrimagnetic alloys: Both helicity-independent and helicity-dependent all-optical switching\nprocesses driven by single ultrashort laser pulse have been experimentally\ndemonstrated in ferrimagnetic alloys as GdFeCo. Although the switching has been\npreviously reproduced by atomistic simulations, the lack of a robust\nmicromagnetic framework for ferrimagnets limits the predictions to small\nnano-systems, whereas the experiments are usually performed with lasers and\nsamples of tens of micrometers. Here we develop a micromagnetic model based on\nthe extended Landau-Lifshitz-Bloch equation, which is firstly validated by\ndirectly reproducing atomistic results for small samples and uniform laser\nheating. After that, the model is used to study ultrafast single shot\nall-optical switching in ferrimagnetic alloys under realistic conditions. We\nfind that the helicity-independent switching under a linearly polarized laser\npulse is a pure thermal phenomenon, in which the size of inverted area directly\ncorrelates with the maximum electron temperature in the sample. On the other\nhand, the analysis of the helicity-dependent processes under circular polarized\npulses in ferrimagnetic alloys with different composition indicates qualitative\ndifferences between the results predicted by the magnetic circular dichroism\nand the ones from inverse Faraday effect. Based on these predictions, we\npropose experiments that would allow to resolve the controversy over the\nphysical phenomenon that underlies these helicity-dependent all optical\nprocesses.",
        "positive": "Degradation of phonons in disordered moir\u00e9 superlattices: The elastic collective modes of a moir\\'e superlattice arise not from\nvibrations of a rigid crystal but from the relative displacement between the\nconstituent layers. Despite their similarity to acoustic phonons, these modes,\ncalled phasons, are not protected by any conservation law. Here, we show that\ndisorder in the relative orientation between the layers and thermal\nfluctuations associated with their sliding motion degrade the propagation of\nsound in the moir\\'e superlattice. Specifically, the phason modes become\noverdamped at low energies and acquire a finite gap, which displays a universal\ndependence on the twist-angle variance. Thus, twist-angle inhomogeneity is\nmanifested not only in the non-interacting electronic structure of moir\\'e\nsystems, but also in their phonon-like modes. More broadly, our results have\nimportant implications for the electronic properties of twisted moir\\'e systems\nthat are sensitive to the electron-phonon coupling."
    },
    {
        "anchor": "Direct observation of the Aharonov-Casher phase: Ring structures fabricated from HgTe/HgCdTe quantum wells have been used to\nstudy Aharonov-Bohm type conductance oscillations as a function of Rashba\nspin-orbit splitting strength. We observe non-monotonic phase changes\nindicating that an additional phase factor modifies the electron wave function.\nWe associate these observations with the Aharonov-Casher effect. This is\nconfirmed by comparison with numerical calculations of the magneto-conductance\nfor a multichannel ring structure within the Landauer-B\\\"uttiker formalism.",
        "positive": "Manifestation of many-body interactions in the integer quantum Hall\n  effect regime: We use the self-consistent Hartree-Fock approximation for numerically\naddressing the integer quantum Hall (IQH) regime in terms of many-body physics\nat higher Landau levels (LL). The results exhibit a strong tendency to avoid\nthe simultaneous existence of partly filled spin-up and spin-down LLs. Partly\nfilled LLs appear as a mixture of coexisting regions of full and empty LLs. We\nobtain edge stripes with approximately constant filling factor $\\nu$ close to\nhalf-odd filling at the boundaries between the regions of full and empty LLs,\nwhich we explain in terms of the $g$-factor enhancement as a function of a\nlocally varying $\\nu$ across the compressible stripes.The many-particle\ninteractions follow a behaviour as it would result from applying Hund's rule\nfor the occupation of the spin split LLs. The screening of the disorder and\nedge potential appears significantly reduced as compared to screening based on\na Thomas-Fermi approximation. For addressing carrier transport, we use a\nnon-equilibrium network model (NNM) that handles the lateral distribution of\nthe experimentally injected non-equilibrium chemical potentials $\\mu$."
    },
    {
        "anchor": "Colloquium: Topological Band Theory: The first-principles band theory paradigm has been a key player not only in\nthe process of discovering new classes of topologically interesting materials,\nbut also for identifying salient characteristics of topological states,\nenabling direct and sharpened confrontation between theory and experiment. We\nbegin this review by discussing underpinnings of the topological band theory,\nwhich basically involves a layer of analysis and interpretation for assessing\ntopological properties of band structures beyond the standard band theory\nconstruct. Methods for evaluating topological invariants are delineated,\nincluding crystals without inversion symmetry and interacting systems. The\nextent to which theoretically predicted properties and protections of\ntopological states have been verified experimentally is discussed, including\nwork on topological crystalline insulators, disorder/interaction driven\ntopological insulators (TIs), topological superconductors, Weyl semimetal\nphases, and topological phase transitions. Successful strategies for new\nmaterials discovery process are outlined. A comprehensive survey of currently\npredicted 2D and 3D topological materials is provided. This includes binary,\nternary and quaternary compounds, transition metal and f-electron materials,\nWeyl and 3D Dirac semimetals, complex oxides, organometallics, skutterudites\nand antiperovskites. Also included is the emerging area of 2D atomically thin\nfilms beyond graphene of various elements and their alloys, functional thin\nfilms, multilayer systems, and ultra-thin films of 3D TIs, all of which hold\nexciting promise of wide-ranging applications. We conclude by giving a\nperspective on research directions where further work will broadly benefit the\ntopological materials field.",
        "positive": "Temperature dependent spin transport properties of Platinum inferred\n  from spin Hall magnetoresistance measurements: We study the temperature dependence of the spin Hall magnetoresistance (SMR)\nin yttrium iron garnet/platinum hybrid structures via magnetization orientation\ndependent magnetoresistance measurements. Our experiments show a decrease of\nthe SMR magnitude with decreasing temperature. Using the sensitivity of the SMR\nto the spin transport properties of the normal metal, we interpret our data in\nterms of a decrease of the spin Hall angle in platinum from 0.11 at room\ntemperature to 0.075 at 10K, while the spin diffusion length and the spin\nmixing conductance of the ferrimagnetic insulator/normal metal interface remain\nalmost constant."
    },
    {
        "anchor": "Quantum interference in HgTe structures: We study quantum transport in HgTe/HgCdTe quantum wells under the condition\nthat the chemical potential is located outside of the bandgap. We first analyze\nsymmetry properties of the effective Bernevig-Hughes-Zhang Hamiltonian and the\nrelevant symmetry-breaking perturbations. Based on this analysis, we overview\npossible patterns of symmetry breaking that govern the quantum interference\n(weak localization or weak antilocalization) correction to the conductivity in\ntwo dimensional HgTe/HgCdTe samples. Further, we perform a microscopic\ncalculation of the quantum correction beyond the diffusion approximation.\nFinally, the interference correction and the low-field magnetoresistance in a\nquasi-one-dimensional geometry are analyzed.",
        "positive": "Energy levels of gapped graphene quantum dots in external fields: We investigate the energy levels of fermions within a circular graphene\nquantum dot (GQD) subjected to external magnetic and Aharonov-Bohm fields.\nSolving the eigenvalue equation for two distinct regions allows us to determine\nthe eigenspinors for the valleys $K$ and $K^\\prime$. By establishing the\ncontinuity of eigenspinors at the GQD interface, we derive an equation that\nreveals the reliance of energy levels on external physical parameters. Our\nobservations suggest that the symmetry of energy levels hinges on the selected\nphysical parameters. We observe that at low magnetic fields, the energy levels\ndisplay degeneracy, which diminishes as the field strength increases,\ncoinciding with the convergence of energy levels toward the Landau levels. We\nillustrate that the introduction of a magnetic flux into the GQD leads to the\ncreation of an energy gap, extending the trapping time of electrons without\nperturbing the system. Conversely, the addition of gap energy widens the band\ngap, disrupting the system's symmetry by introducing new energy levels."
    },
    {
        "anchor": "Strong anisotropic optical conductivity in two dimensional puckered\n  structures: The role of Rashba effect: We calculate the optical conductivity of an anisotropic two-dimensional\nsystem with Rashba spin-flip excitation within the Kubo formalism. We show that\nthe anisotropic Rashba effect caused by an external field changes significantly\nthe magnitude of the spin splitting. Furthermore, we obtain an analytical\nexpression for the longitudinal optical conductivity associated with inter-band\ntransitions as a function of the frequency for an arbitrary polarization angle.\nWe find that the diagonal components of the optical conductivity tensor are\ndirection-dependent and the spectrum of optical absorption is strongly\nanisotropic with an absorption window. The height and width of this absorption\nwindow are very sensitive to the system anisotropy. While the height of\nabsorption peak increases with increasing effective mass anisotropy ratio, the\npeak intensity is larger when the light polarization is along the armchair\ndirection. Moreover, the absorption peak width becomes broader as the density\nof state mass or Rashba interaction is enhanced. These features can be used to\ndetermine parameters relevant for spintronics through the optical absorption\nspectrum.",
        "positive": "Topological insulator: a new quantized spin Hall resistance robust to\n  dephasing: The influence of dephasing on the quantum spin Hall effect (QSHE) is studied.\nIn the absence of dephasing, the longitudinal resistance in a QSHE system\nexhibits the quantum plateaus. We find that these quantum plateaus are robust\nagainst the normal dephasing but fragile with the spin dephasing. Thus, these\nquantum plateaus only survive in mesoscopic samples. Moreover, the longitudinal\nresistance increases linearly with the sample length but is insensitive to the\nsample width. These characters are in excellent agreement with the recent\nexperimental results [science {\\bf 318}, 766 (2007)]. In addition, we define a\nnew spin Hall resistance that also exhibits quantum plateaus. In particular,\nthese plateaus are robust against any type of dephasing and therefore, survive\nin macroscopic samples and better reflect the topological nature of QSHE."
    },
    {
        "anchor": "Modulation of pure spin currents with a ferromagnetic insulator: We propose and demonstrate spin manipulation by magnetically controlled\nmodulation of pure spin currents in cobalt/copper lateral spin valves,\nfabricated on top of the magnetic insulator Y$_3$Fe$_5$O$_{12}$ (YIG). The\ndirection of the YIG magnetization can be controlled by a small magnetic field.\nWe observe a clear modulation of the non-local resistance as a function of the\norientation of the YIG magnetization with respect to the polarization of the\nspin current. Such a modulation can only be explained by assuming a finite\nspin-mixing conductance at the Cu/YIG interface, as it follows from the\nsolution of the spin-diffusion equation. These results open a new path towards\nthe development of spin logics.",
        "positive": "Spin-transport, spin-torque and memory in antiferromagnetic devices:\n  Part of a collection of reviews on antiferromagnetic spintronics: Ferromagnets are key materials for sensing and memory applications. In\ncontrast, antiferromagnets that represent the more common form of magnetically\nordered materials, have so far found less practical application beyond their\nuse for establishing reference magnetic orientations via exchange bias. This\nmight change in the future due to the recent progress in materials research and\ndiscoveries of antiferromagnetic spintronic phenomena suitable for device\napplications. Experimental demonstrations of the electrical switching and\nelectrical detection of the N\\'eel order open a route towards memory devices\nbased on antiferromagnets. Apart from the radiation and magnetic-field\nhardness, memory cells fabricated in antiferromagnets are inherently multilevel\nwhich could be used for neuromorphic computing. Switching speeds attainable in\nantiferromagnets far exceed those of the ferromagnetic and semiconductor memory\ntechnologies. Here we review the recent progress in electronic spin-transport\nand spin-torque phenomena in antiferromagnets that are dominantly of the\nrelativistic quantum mechanics origin. We discuss their utility in pure\nantiferromagnetic or hybrid ferromagnetic/antiferromagnetic memory devices"
    },
    {
        "anchor": "Self-organization of irregular NEM vibrations in multi-mode shuttle\n  structures: We investigate theoretically multi-mode electromechanical \"shuttle\"\ninstabilities in DC voltage-biased nanoelectromechanical single-electron\ntunneling (NEM-SET) devices. We show that initially irregular (quasi-periodic)\noscillations, that occur as a result of the simultaneous self-excitation of\nseveral mechanical modes with incommensurable frequencies, self-organize into\nperiodic oscillations with a frequency corresponding to the eigenfrequency of\none of the unstable modes. This effect demonstrates that a local probe can\nselectively excite global vibrations of extended objects.",
        "positive": "Deduction of Pure Spin Current from Spin Linear and Circular\n  Photogalvanic Effect in Semiconductor Quantum Wells: We study the spin photogalvanic effect in two-dimensional electron system\nwith structure inversion asymmetry by means of the solution of semiconductor\noptical Bloch equations. It is shown that a linearly polarized light may inject\na pure spin current in spin-splitting conduction bands due to Rashba spin-orbit\ncoupling, while a circularly polarized light may inject spin-dependent\nphotocurrent. We establish an explicit relation between the photocurrent by\noblique incidence of a circularly polarized light and the pure spin current by\nnormal incidence of a linearly polarized light such that we can deduce the\namplitude of spin current from the measured spin photocurrent experimentally.\nThis method may provide a source of spin current to study spin transport in\nsemiconductors quantitatively."
    },
    {
        "anchor": "Noise in electromigrated nanojunctions: Noise measurements are a probe beyond simple electronic transport that can\nreveal additional information about electronic correlations and inelastic\nprocesses. Here we report noise measurements in individual electromigrated\nnanojunctions, examining the evolution from the many channel regime to the\ntunneling regime, using a radio frequency technique. While we generally observe\nthe dependence of noise on bias expected for shot noise, in approximately 12%\nof junction configurations we find discrete changes in the bias dependence at\nthreshold values of the bias, consistent with electronic excitation of local\nvibrational modes. Moreover, with some regularity we find significant\nmesoscopic variation in the magnitude of the noise in particular junctions even\nwith small changes in the accompanying conductance. In another $\\sim$17% of\njunctions we observe pronounced asymmetries in the inferred noise magnitude as\na function of bias polarity, suggesting that investigators should be concerned\nabout current-driven ionic motion in the electrodes even at biases well below\nthose used for deliberate electromigration.",
        "positive": "Coupling between Edge and Bulk in Strong-Field Quantum Dots: The maximum-density-droplet (MDD) state of quantum-dot electrons becomes\nunstable at strong magnetic fields to the addition of interior holes. Using\nexact diagonalization, we demonstrate that the first hole is located at the\ncenter of the dot when the number of electrons $N$ is smaller than $\\sim 14$\nand is located away from the center for larger dots. The separation between\nfield strengths at which additional holes are introduced becomes small for\nlarge dots, explaining recent observations of a rapid increase in dot area when\nthe magnetic field is increased beyond the MDD stability limit. We comment on\ncorrelations between interior hole and collective edge fluctuations, and on the\nimplications of these correlations for edge excitation models in bulk systems."
    },
    {
        "anchor": "Giant chirality-induced spin polarization in twisted transition metal\n  dichalcogenides: Chirality-induced spin selectivity (CISS) is an effect that has recently\nattracted a great deal of attention in chiral chemistry and that remains to be\nunderstood. In the CISS effect, electrons passing through chiral molecules\nacquire a large degree of spin polarization. In this work we study the case of\natomically-thin chiral crystals created by van der Waals assembly. We show that\nthis effect can be spectacularly large in systems containing just two\nmonolayers, provided they are spin-orbit coupled. Its origin stems from the\ncombined effects of structural chirality and spin-flipping spin-orbit coupling.\nWe present detailed calculations for twisted homobilayer transition metal\ndichalcogenides, showing that the chirality-induced spin polarization can be\ngiant, e.g. easily exceeding $50\\%$ for ${\\rm MoTe}_2$. Our results clearly\nindicate that twisted quantum materials can operate as a fully tunable platform\nfor the study and control of the CISS effect in condensed matter physics and\nchiral chemistry.",
        "positive": "Ground state spin and excitation energies in half-filled Lieb lattices: We present detailed spectral calculations for small Lieb lattices having up\nto $N=4$ number of cells, in the regime of half-filling, an instance of\nparticular relevance for the nano-magnetism of discrete systems such as quantum\ndot arrays, due to the degenerate levels at mid-spectrum. While for the Hubbard\ninteraction model -and even number of sites- the ground state spin is given by\nthe Lieb theorem, the inclusion of long range interaction -or odd number of\nsites- make the spin state not a priori known, which justifies our approach. We\ncalculate also the excitation energies, which are of experimental importance,\nand find significant variation induced by the interaction potential. One\nobtains insights on the mechanisms involved that impose as ground state the\nLieb state with lower spin rather than the Hund one with maximum spin for the\ndegenerate levels, showing this in the first and second order of the\ninteraction potential for the smaller lattices. The analytical results concorde\nwith the numerical ones, which are performed by exact diagonalization\ncalculations or by a combined mean-field and configuration interaction method.\nWhile the Lieb state is always lower in energy than the Hund state, for strong\nlong-range interaction, when possible, another minimal spin state is imposed as\nground state."
    },
    {
        "anchor": "Engineering Plateau Phase Transition in Quantum Anomalous Hall\n  Multilayers: The plateau phase transition in quantum anomalous Hall (QAH) insulators\ncorresponds to a quantum state wherein a single magnetic domain gives way to\nmultiple magnetic domains and then re-converges back to a single magnetic\ndomain. The layer structure of the sample provides an external knob for\nadjusting the Chern number C of the QAH insulators. Here, we employ molecular\nbeam epitaxy (MBE) to grow magnetic topological insulator (TI) multilayers with\nan asymmetric layer structure and realize the magnetic field-driven plateau\nphase transition between two QAH states with odd Chern number change {\\Delta}C.\nIn multilayer structures with C=+-1 and C=+-2 QAH states, we find two\ncharacteristic power-law behaviors between temperature and the scaling\nvariables on the magnetic field at transition points. The critical exponents\nextracted for the plateau phase transitions with {\\Delta}C=1 and {\\Delta}C=3 in\nQAH insulators are found to be nearly identical, specifically, k1~0.390+-0.021\nand k2~0.388+-0.015, respectively. We construct a four-layer Chalker-Coddington\nnetwork model to understand the consistent critical exponents for the plateau\nphase transitions with {\\Delta}C=1 and {\\Delta}C=3. This work will motivate\nfurther investigations into the critical behaviors of plateau phase transitions\nwith different {\\Delta}C in QAH insulators and provide new opportunities for\nthe development of QAH chiral edge current-based electronic and spintronic\ndevices.",
        "positive": "A charge-driven feedback loop in the resonance fluorescence of a single\n  quantum dot: Semiconductor quantum dots can emit antibunched, single photons on demand\nwith narrow linewidths. However, the observed linewidths are broader than\nlifetime measurements predict, due to spin and charge noise in the environment.\nThis noise randomly shifts the transition energy and destroys coherence and\nindistinguishability of the emitted photons. Fortunately, the fluctuations can\nbe reduced by a stabilization using a suitable feedback loop. In this work we\ndemonstrate a fast feedback loop that manifests itself in a strong hysteresis\nand bistability of the exciton resonance fluorescence signal. Field ionization\nof photogenerated quantum dot excitons leads to the formation of a charged\ninterface layer that drags the emission line along over a frequency range of\nmore than 30 GHz. This internal charge-driven feedback loop could be used to\nreduce the spectral diffusion and stabilize the emission frequency within\nmilliseconds, presently only limited by the sample structure, but already\nfaster than nuclear spin feedback."
    },
    {
        "anchor": "Global Phase Diagram of a Dirty Weyl Liquid and Emergent\n  Superuniversality: Pursuing complementary field-theoretic and numerical methods, we here paint\nthe global phase diagram of a three-dimensional dirty Weyl system. The\ngeneralized Harris criterion, augmented by a perturbative renormalization-group\n(RG) analysis shows that weak disorder is an irrelevant perturbation at the\nWeyl semimetal(WSM)-insulator quantum critical point (QCP). But, a metallic\nphase sets in through a quantum phase transition (QPT) at strong disorder\nacross a multicritical point (MCP). The field theoretic predictions for the\ncorrelation length exponent $\\nu=2$ and dynamic scaling exponent $z=5/4$ at\nthis MCP are in good agreement with the ones extracted numerically, yielding\n$\\nu=1.98 \\pm 0.10$ and $z=1.26 \\pm 0.05$, from the scaling of the average\ndensity of states (DOS). Deep inside the WSM phase, generic disorder is also an\nirrelevant perturbation, while a metallic phase appears at strong disorder\nthrough a QPT. We here demonstrate that in the presence of generic, but strong\ndisorder the WSM-metal QPT is ultimately always characterized by the exponents\n$\\nu=1$ and $z=3/2$ (to one-loop order), originating from intra-node or chiral\nsymmetric (e.g., regular and axial potential) disorder. We here anchor such\nemergent \\emph{chiral superuniversality} through complementary RG calculations,\ncontrolled via $\\epsilon$-expansions, and numerical analysis of average DOS\nacross WSM-metal QPT. In addition, we also discuss a subsequent QPT (at even\nstronger disorder) of a Weyl metal into an Anderson insulator by numerically\ncomputing the typical DOS at zero energy. The scaling behavior of various\nphysical observables, such as residue of quasiparticle pole, dynamic\nconductivity, specific heat, Gr$\\ddot{\\mbox{u}}$neisen ratio, inside various\nphases as well as across various QPTs in the global phase diagram of a dirty\nWeyl liquid are discussed.",
        "positive": "Strain-induced thermoelectricity in pentacene: The present work discusses a non-synthetic strategy to achieve a favorable\nthermoelectric response in pentacene via strain. It is found that a uni-axial\nstrain is capable of inducing spatial anisotropy in the molecule. As a result,\nthe transmission spectrum becomes highly asymmetric under a particular strained\nscenario, which is the primary requirement to get a favorable thermoelectric\nresponse. Different thermoelectric quantities are computed for the\nstrain-induced pentacene using Green's function formalism following the\nLandauer-Buttiker prescription. Various scenarios are considered to make the\npresent work more realistic, such as the effects of substrate, coupling\nstrength between the molecule and electrodes, dangling bonds, etc. Such a\nscheme to enhance the thermoelectric performance in pentacene is\ntechnologically intriguing and completely new to the best of our knowledge."
    },
    {
        "anchor": "Damping of mechanical vibrations by free electrons in metallic\n  nanoresonators: We investigate the effect of free electrons on the quality factor (Q) of a\nmetallic nanomechanical resonator in the form of a thin elastic beam. The\nflexural and longitudinal modes of the beam are modeled using thin beam\nelasticity theory, and simple perturbation theory is used to calculate the rate\nat which an externally excited vibration mode decays due to its interaction\nwith free electrons. We find that electron-phonon interaction significantly\naffects the Q of longitudinal modes, and may also be of significance to the\ndamping of flexural modes in otherwise high-Q beams. The finite geometry of the\nbeam is manifested in two important ways. Its finite length breaks translation\ninvariance along the beam and introduces an imperfect momentum conservation law\nin place of the exact law. Its finite width imposes a quantization of the\nelectronic states that introduces a temperature scale for which there exists a\ncrossover from a high-temperature macroscopic regime, where electron-phonon\ndamping behaves as if the electrons were in the bulk, to a low-temperature\nmesoscopic regime, where damping is dominated by just a few dissipation\nchannels and exhibits sharp non-monotonic changes as parameters are varied.\nThis suggests a novel scheme for probing the electronic spectrum of a nanoscale\ndevice by measuring the Q of its mechanical vibrations.",
        "positive": "Signature of Fermi arc surface states in Andreev reflection at the\n  WTe$_2$ Weyl semimetal surface: We experimentally investigate charge transport through the interface between\na niobium superconductor and a three-dimensional WTe$_2$ Weyl semimetal. In\naddition to classical Andreev reflection, we observe sharp non-periodic subgap\nresistance resonances. From an analysis of their positions, magnetic field and\ntemperature dependencies, we can interpret them as an analog of Tomasch\noscillations for transport along the topological surface state across the\nregion of proximity-induced superconductivity at the Nb-WTe$_2$ interface.\nObservation of distinct geometrical resonances implies a specific transmission\ndirection for carriers, which is a hallmark of the Fermi arc surface states."
    },
    {
        "anchor": "Tuned gap in graphene through laser barrier: We study the effect of the energy gap on the transmission of fermions in\ngraphene exposed to linearly polarized light as a laser barrier. We determine\nthe energy spectrum, apply boundary conditions at interfaces, and use the\ntransfer matrix approach to obtain transmissions for all energy modes. We show\nthat when the energy gap increases, the oscillations of transmissions decrease\ndramatically until they vanish entirely. However, when the barrier width\nvaries, the oscillations become more significant and exhibit sharp peaks. By\nincreasing the incident energy, the laser field suppresses the Fabry-P\\'erot\nresonance, and the transmissions move to the right when the energy gap is\ntuned.",
        "positive": "Transient heat generation in a quantum dot under a step-like pulse bias: We study the transient heat generation in a quantum dot system driven by a\nstep-like or a square-shaped pulse bias. We find that a periodically\noscillating heat generation arises after adding the sudden bias. One\nparticularly surprising result is that there exists a heat absorption from the\nzero-temperature phonon subsystem. Thus the phonon population in\nnon-equilibrium can be less than that of the equilibrium electron-phonon\nsystem. In addition, we also ascertain the optimal conditions for the operation\nof a quantum dot with the minimum heat generation."
    },
    {
        "anchor": "Superconducting flux-flow type ultra-low-noise magnetic sensors - An\n  alternative to dc-SQUIDs: A superconducting magnetometers based on the magnetic field dependence of the\nEck step voltage in long Josephson tunnel junctions (LJTJs) is demonstrated.\nThe field to be measured is applied perpendicular to a continuous\nsuperconducting pickup loop. Wherever the loop has a narrow constriction, the\ndensity of the flux-restoring circulating currents will become relatively high\nand will locally create a magnetic field large enough to bring a biased LJTJ in\nthe flux-flow state, i.e., at a finite voltage proportional to the field\nstrength. This method allows the realization of a novel family of robust and\ngeneral-purpose superconducting devices which, despite their simplicity,\nfunction as ultra-low-noise, wide-band and high-dynamics magnetometers. The\nperformances of low-T$_c$ sensor prototypes, among which a highly linear\nvoltage responsivity and a magnetic spectral density $S_B^{1/2}<\n3\\,fT/Hz^{1/2}$, promise to be competitive with those of the best\nsuperconducting quantum interference devices.",
        "positive": "Aharonov-Bohm Oscillations in Singly-Connected Disordered Conductors: We show that transport and thermodynamic properties of\n\\emph{singly-connected} disordered conductors exhibit quantum Aharonov - Bohm\noscillations with the total magnetic flux through the system. The oscillations\nare associated with the interference contribution from a special class of\nelectron trajectories confined to the surface of the sample."
    },
    {
        "anchor": "Proximity-induced supercurrent through topological insulator based\n  nanowires for quantum computation studies: Proximity induced superconducting energy gap in the surface states of\ntopological insulators has been predicted to host the much wanted Majorana\nfermions for fault tolerant quantum computation. Recent theoretically proposed\narchitectures for topological quantum computation via Majoranas are based on\nlarge networks of Kitaevs one dimensional quantum wires, which pose a huge\nexperimental challenge in terms of scalability of the current single nanowire\nbased devices. Here, we address this problem by realizing robust\nsuperconductivity in junctions of fabricated topological insulator Bi2Se3\nnanowires proximity coupled to conventional s wave superconducting W\nelectrodes. Milling technique possesses great potential in fabrication of any\ndesired shapes and structures at nanoscale level, and therefore can be\neffectively utilized to scale up the existing single nanowire based design into\nnanowire based network architectures. We demonstrate the dominant role of\nballistic topological surface states in propagating the long range proximity\ninduced superconducting order with high IcRN product in long Bi2Se3 junctions.\nLarge upper critical magnetic fields exceeding the Chandrasekhar Clogston limit\nsuggests the existence of robust superconducting order with spin triplet cooper\npairing. An unconventional inverse dependence of IcRN product on the width of\nthe nanowire junction was also observed.",
        "positive": "Skyrmion Liquid Phase of the Quantum Ferromagnet in Two Dimensions: The two-dimensional quantum ferromagnet filled with a liquid of skyrmions is\nstudied theoretically in the context of the quantum Hall effect near electronic\nfilling factor $\\nu = 1$. A cross-over between the classical ferromagnetic\nphase at $\\nu =1$ and a classical paramagnetic phase at $\\nu \\neq 1$ is\nobtained, which is consistent with recent Knight-shift measurements. A new\ncollective mode associated with the skyrmion liquid that is of the cyclotron\ntype is also identified."
    },
    {
        "anchor": "Fano Resonance and Orbital Filtering in Multiply Connected Carbon\n  Nanotubes: We investigate the electron transport in multiply connected metallic carbon\nnanotubes within the Landauer-B\\\"{u}ttiker formalism. Quasibound states coupled\nto the incident $\\pi^{*}$ states give rise to energy levels of different widths\ndepending on the coupling strength. In particular, donorlike states originating\nfrom heptagonal rings are found to give a very narrow level. Interference\nbetween broad and narrow levels produces Fano-type resonant backscattering as\nwell as resonant tunneling. Over a significantly wide energy range, almost\nperfect suppression of the conduction of $\\pi^{*}$ electrons occurs, which may\nbe regarded as filtering of particular electrons ($\\pi$-pass filter).",
        "positive": "Hybrid graphene-quantum dot phototransistors with ultrahigh gain: Graphene has emerged as a novel platform for opto-electronic applications and\nphotodetector, but the inefficient conversion from light to current has so far\nbeen an important roadblock. The main challenge has been to increase the light\nabsorption efficiency and to provide a gain mechanism where multiple charge\ncarriers are created from one incident photon. Here, we take advantage of the\nstrong light absorption in quantum dots and the two-dimensionality and high\nmobility of graphene to merge these materials into a hybrid system for\nphotodetection with extremely high sensitivity. Exploiting charge transfer\nbetween the two materials, we realize for the first time, graphene-based\nphototransistors that show ultrahigh gain of 10^8 and ten orders of magnitude\nlarger responsivity compared to pristine graphene photodetectors. These hybrid\ngraphene-quantum dot phototransistors exhibit gate-tunable sensitivity,\nspectral selectivity from the shortwave infrared to the visible, and can be\nintegrated with current circuit technologies."
    },
    {
        "anchor": "Strain-tunable direct band gap of ZnO monolayer in graphene-like\n  honeycomb structure: Using full-potential density functional calculations within local density\napproximation (LDA), we found mechanically tunable band-gap in ZnO monolayer\n(ML-ZnO) in graphene-like honeycomb structure, by simulated application of\nin-plane homogeneous biaxial strain. Unstrained ML-ZnO was found to have a\ndirect band gap of energy 1.68 eV within LDA; the actual band gap would be\nmore, since LDA is known to underestimate the gap. Within our simulated strain\nlimit of about plus or minus 10%, the band gap remains direct and shows a\nstrong non-linear variation with strain. The results may find applications in\nfuture nano-electromechanical systems (NEMS) and nano-optomechanial systems\n(NOMS).",
        "positive": "Precise determination of critical points of topological phase\n  transitions via shift current in two-dimensional inversion asymmetric\n  insulators: The precise determination of critical point is the basis to extract various\ncritical properties of phase transitions. We identify that for two-dimensional\ninversion asymmetric insulators, with and without time-reversal symmetry, when\ntopological phase transitions take place, all nonvanishing components of\nband-edge shift current tensor will reverse their signs in a singular way,\nregardless of what realistic value the temperature takes. This remarkable\nsign-reversal behavior of band-edge shift current tensor thus can be applied to\ndetermine the critical points of various topological phase transitions\nprecisely, even for temperature-driven ones. We suggest concrete materials to\ntest our predictions."
    },
    {
        "anchor": "Dirac edges of fractal magnetic minibands in graphene with hexagonal\n  moire superlattices: We find a systematic reappearance of massive Dirac features at the edges of\nconsecutive minibands formed at magnetic fields B_{p/q}= p\\phi_0/(qS) providing\nrational magnetic flux through a unit cell of the moire superlattice created by\na hexagonal substrate for electrons in graphene. The Dirac-type features in the\nminibands at B=B_{p/q} determine a hierarchy of gaps in the surrounding fractal\nspectrum, and show that these minibands have topological insulator properties.\nUsing the additional $q$-fold degeneracy of magnetic minibands at B_{p/q}, we\ntrace the hierarchy of the gaps to their manifestation in the form of\nincompressible states upon variation of the carrier density and magnetic field.",
        "positive": "Evolution of Asymmetric Raman line-shape from nano-structures: A step-by-step evolution of an asymmetric Raman line-shape function from a\nLorentzian line-shape is presented here for low dimensional semiconductors. The\nevolution reported here is based on the phonon confinement model which is\nsuccessfully used in literature to explain the asymmetric Raman line-shape from\nsemiconductor nano-structures. Physical significance of different terms in the\ntheoretical asymmetric Raman line-shape has been explained here. Better\nunderstanding of theoretical reasoning behind each term allows one to use the\ntheoretical Raman line-shape without going into details of theory from first\nprinciple. This will enable one to empirically derive a theoretical Raman\nline-shape function for any material if information about its phonon\ndispersion, size dependence etc is known."
    },
    {
        "anchor": "Microwave-induced nonequilibrium temperature in a suspended carbon\n  nanotube: Antenna-coupled suspended single carbon nanotubes exposed to 108 GHz\nmicrowave radiation are shown to be selectively heated with respect to their\nmetal contacts. This leads to an increase in the conductance as well as to the\ndevelopment of a power-dependent DC voltage. The increased conductance stems\nfrom the temperature dependence of tunneling into a one-dimensional electron\nsystem. The DC voltage is interpreted as a thermovoltage, due to the increased\ntemperature of the electron liquid compared to the equilibrium temperature in\nthe leads.",
        "positive": "Electrokinetic origin of swirling flow on nanoscale interface: The zeta ($\\zeta$) potential is a pivotal metric for characterizing the\nelectric field topology within an electric double layer - an important\nphenomenon on phase interface. It underpins critical processes in diverse\nrealms such as chemistry, biomedical engineering, and micro/nanofluidics. Yet,\nlocal measurement of $\\zeta$ potential at the interface has historically\npresented challenges, leading researchers to simplify a chemically homogenized\nsurface with a uniform $\\zeta$ potential. In the current investigation, we\npresent evidence that, within a microchannel, the spatial distribution of\n$\\zeta$ potential across a chemically homogeneous solid-liquid interface can\nbecome two-dimensional (2D) under an imposed flow regime, as disclosed by a\nstate-of-art fluorescence photobleaching electrochemistry analyzer (FLEA)\ntechnique. The $\\zeta$ potential' s propensity to become increasingly negative\ndownstream, presents an approximately symmetric, V-shaped pattern in the\nspanwise orientation. Intriguingly, and of notable significance to chemistry\nand engineering, this 2D $\\zeta$ potential framework was found to\nelectrokinetically induce swirling flows in tens of nanometers, aligning with\nthe streamwise axis, bearing a remarkable resemblance to the well-documented\nhairpin vortices in turbulent boundary layers. Our findings gesture towards a\nnovel perspective on the genesis of vortex structures in nanoscale.\nAdditionally, the FLEA technique emerges as a potent tool for discerning\n$\\zeta$ potential at a local scale with high resolution, potentially\naccelerating the evolution and applications of novel surface material."
    },
    {
        "anchor": "Invariants in the paramagnetic resonance spectra of impurity crystals: We show that in cubic crystals with anisotropic impurity centers the sum of\nsquares of the magnetic resonance (EPR) frequencies is invariant with respect\nto the magnetic field direction. The connection between such an invariant and\nthe g-tensor components of the impurity is derived for different types of\ncenters. The established regularity is confirmed experimentally for the\nspin-noise spectra of a CaF2-Nd3+ crystal. We show how this property of the EPR\nspectra can be efficiently used for the assignment of paramagnetic centers in\ncubic crystals.",
        "positive": "Ultra-low-energy computing paradigm using giant spin Hall devices: Spin Hall effect converts charge current to spin current, which can exert\nspin-torque to switch the magnetization of a nanomagnet. Recently, it is shown\nthat the ratio of spin current to charge current using spin Hall effect can be\nmade more than unity by using the areal geometry judiciously, unlike the case\nof conventional spin-transfer-torque switching of nanomagnets. This can enable\nenergy-efficient means to write a bit of information in nanomagnets. Here, we\nstudy the energy dissipation in such spin Hall devices. By solving stochastic\nLandau-Lifshitz-Gilbert equation of magnetization dynamics in the presence of\nroom temperature thermal fluctuations, we show a methodology to simultaneously\nreduce switching delay, its variance and energy dissipation, while lateral\ndimensions of the spin Hall devices are scaled down."
    },
    {
        "anchor": "Statistics of Current Fluctuations and Electron-Electron Interactions in\n  Mesoscopic Coherent Conductors: We formulate a general path integral approach which describes statistics of\ncurrent fluctuations in mesoscopic coherent conductors at arbitrary frequencies\nand in the presence of interactions. Applying this approach to the\nnon-interacting case, we analyze the frequency dispersion of the third cumulant\nof the current operator ${\\cal S}_3$ at frequencies well below both the inverse\ncharge relaxation time and the inverse electron dwell time. This dispersion\nturns out to be important in the frequency range comparable to applied\nvoltages. For comparatively transparent conductors it may lead to the sign\nchange of ${\\cal S}_3$. We also analyze the behavior of the second cumulant of\nthe current operator ${\\cal S}_2$ (current noise) in the presence of\nelectron-electron interactions. In a wide range of parameters we obtain\nexplicit universal dependencies of ${\\cal S}_2$ on temperature, voltage and\nfrequency. We demonstrate that Coulomb interaction decreases the Nyquist noise.\nIn this case the interaction correction to the noise spectrum is governed by\nthe combination $\\sum_nT_n(T_n-1)$, where $T_n$ is the transmission of the\n$n$-th conducting mode. The effect of electron-electron interactions on the\nshot noise is more complicated. At sufficiently large voltages we recover two\ndifferent interaction corrections entering with opposite signs. The net result\nis proportional to $\\sum_nT_n(T_n-1)(1-2T_n)$, i.e. Coulomb interaction\ndecreases the shot noise at low transmissions and increases it at high\ntransmissions.",
        "positive": "i-Josephson Junction as Topological Superconductor: We show that the time reversal symmetry inevitably breaks in a\nsuperconducting Josephson junction formed by two superconductors with different\npairing symmetries dubbed as i-Josephson junction. While the leading\nconventional Josephson coupling vanishes in such an i-Josephson junction, the\nsecond order coupling from tunneling always generates chiral superconductivity\norders with broken time reversal symmetry. Josephson frequency in the\ni-junction is doubled, namely $\\omega = 4eV /h$. The result provides a way to\nengineer topological superconductivity such as the d + id' -wave\nsuperconducting state characterized by a nonzero Chern number."
    },
    {
        "anchor": "Fermi-edge transmission resonance in graphene driven by a single Coulomb\n  impurity: The interaction between the Fermi sea of conduction electrons and a\nnon-adiabatic attractive impurity potential can lead to a power-law divergence\nin the tunneling probability of charge through the impurity. The resulting\neffect, known as the Fermi edge singularity (FES), constitutes one of the most\nfundamental many-body phenomena in quantum solid state physics. Here we report\nthe first observation of FES for Dirac Fermions in graphene driven by isolated\nCoulomb impurities in the conduction channel. In high-mobility graphene devices\non hexagonal boron nitride substrates, the FES manifests in abrupt changes in\nconductance with a large magnitude $\\approx e^{2}/h$ at resonance, indicating\ntotal many-body screening of a local Coulomb impurity with fluctuating charge\noccupancy. Furthermore, we exploit the extreme sensitivity of graphene to\nindividual Coulomb impurities, and demonstrate a new defect-spectroscopy tool\nto investigate strongly correlated phases in graphene in the quantum Hall\nregime.",
        "positive": "Computational capability for physical reservoir computing using a\n  spin-torque oscillator with two free layers: A numerical analysis on the computational capability of physical reservoir\ncomputing utilizing a spin-torque oscillator with two free layers is reported.\nConventional spintronics devices usually consist of two ferromagnets, where the\ndirection of magnetization in one layer, called the free layer, can move while\nthat of the other, the reference layer, is fixed. Recently, however, devices\nwith two free layers, where the reference layer is replaced by another free\nlayer, have been developed for various practical applications. Adding another\nfree layer drastically changes the dynamical response of the device through the\ncouplings via the spin-transfer effect and the dipole magnetic field. A\nnumerical simulation of the Landau-Lifshitz-Gilbert equation and a statistical\nanalyses of the Lyapunov exponent and the synchronization index reveal the\nappearance of an amplitude-modulated oscillation and chaos in the oscillators\nwith two free layers. Such complex dynamics qualitatively change the\ncomputational capability of physical reservoir computing because the\ncomputational resource is dynamics of the physical system. An evaluation of the\nshort-term memory capacity clarifies that oscillators with two free layers have\na larger capacity than those of conventional oscillators. An enhancement in\ncapacity near the edge of echo state property, i.e., the boundary between zero\nand finite synchronization index, is also found."
    },
    {
        "anchor": "The definition of the spin current: The angular spin current and its\n  physical consequences: We find that in order to completely describe the spin transport, apart from\nspin current (or linear spin current), one has to introduce the angular spin\ncurrent. The two spin currents respectively describe the translational and\nrotational motion (precession)of a spin. The definitions of these spin current\ndensities are given and their physical properties are discussed. Both spin\ncurrent densities appear naturally in the spin continuity equation. Moreover we\npredict that the angular spin current can also induce an electric field\n$\\vec{E}$, and in particular $\\vec{E}$ scales as $1/r^2$ at large distance $r$,\nwhereas the $\\vec{E}$ field generated from the linear spin current goes as\n$1/r^3$.",
        "positive": "Anomalous heat conduction in a carbon nanowire: Molecular dynamics\n  calculations: Heat conduction of a real quasi-one dimensional material, the finite length\ncarbon nanowire (CNW), inserted into the single-walled carbon nanotube (SWNT)\nhas been studied by the molecular dynamical (MD) method, in which both of the\nlongitudinal as well as transverse motions of the chain atoms in the SWNT have\nbeen permitted. It is found that the thermal conductivity $\\kappa $ of the\ncarbon nanowire is very high at room temperature, and diverges more likely with\nthe chain length logarithmically."
    },
    {
        "anchor": "Metal-Insulator Transition in a Disordered Two-Dimensional Electron Gas\n  in GaAs-AlGaAs at zero Magnetic Field: A metal-insulator transition in two-dimensional electron gases at B=0 is\nfound in Ga(Al)As heterostructures, where a high density of self-assembled InAs\nquantum dots is incorporated just 3 nm below the heterointerface. The\ntransition occurs at resistances around h/e^2 and critical carrier densities of\n1.2 10^11cm^-2. Effects of electron-electron interactions are expected to be\nrather weak in our samples, while disorder plays a crucial role.",
        "positive": "Comment on \"Theory of phonon-assisted adsorption in graphene: Many-body\n  infrared dynamics'': Two approximations used by Sengupta [Phys. Rev. B {\\bf 100}, 075429 (2019)]\nin numerically computing the adsorption rate of cold hydrogen atoms on\nsuspended graphene are critically examined. The independent boson model\napproximation (IBMA) was used to compute the atom self-energy, and the\nsingle-pole approximation (SPA) was used to obtain the adsorption rate from the\nself-energy. It is shown explicitly that there are additional contributions to\nthe self-energy appearing at the same order of the atom-phonon coupling as the\nIBMA terms that alter the value of the real part of the self-energy at low\nenergies by several orders of magnitude in the regime of interest. This shift\nin the self-energy consequently renders the use of SPA invalid."
    },
    {
        "anchor": "Topological invariants for the Haldane phase of interacting SSH chains\n  -- a functional RG approach: We present a functional renormalization group approach to interacting\ntopological Green function invariants with a focus on the nature of\ntransitions. The method is applied to chiral symmetric fermion chains in the\nMott limit that can be driven into a Haldane phase. We explicitly show that the\ntransition to this phase is accompanied by a zero of the fermion Green\nfunction. Our results for the phase boundary are quantitatively benchmarked\nagainst DMRG data.",
        "positive": "Temperature dependence of D'yakonov-Perel' spin relaxation in zinc\n  blende semiconductor quantum structures: The D'yakonov-Perel' mechanism, intimately related to the spin splitting of\nthe electronic states, usually dominates the spin relaxation in zinc blende\nsemiconductor quantum structures. Previously it has been formulated for the two\nlimiting cases of low and high temperatures. Here we extend the theory to give\nan accurate description of the intermediate regime which is often relevant for\nroom temperature experiments. Employing the self-consistent multiband envelope\nfunction approach, we determine the spin splitting of electron subbands in\nn-(001) zinc blende semiconductor quantum structures. Using these results we\ncalculate spin relaxation rates as a function of temperature and obtain\nexcellent agreement with experimental data."
    },
    {
        "anchor": "Extending the time of coherent optical response in ensemble of\n  singly-charged InGaAs quantum dots: The ability to extend the time scale of the coherent optical response from\nlarge ensembles of quantum emitters is highly appealing for applications in\nquantum information devices. In semiconductor nanostructures, spin degrees of\nfreedom can be used as auxiliary, powerful tools to modify the coherent optical\ndynamics. Here, we apply this approach to negatively charged (In,Ga)As/GaAs\nself-assembled quantum dots which are considered as excellent quantum emitters\nwith robust optical coherence and high bandwidth. We study 3-pulse\nspin-dependent photon echoes subject to moderate transverse magnetic fields up\nto 1 T. We demonstrate that the timescale of coherent optical response can be\nextended by at least an order of magnitude by the field. Without magnetic\nfield, the photon echo decays with $T_ 2$ = 0.45 ns which is determined by the\nradiative lifetime of trions $T_1$ = 0.27 ns. In the presence of the transverse\nmagnetic field, the decay of the photon echo signal is given by spin dephasing\ntime of the ensemble of resident electrons $T_{2,e}$ ~ 4 ns. We demonstrate\nthat the non-zero transverse g-factor of the heavy holes in the trion state\nplays a crucial role in the temporal evolution and magnetic field dependence of\nthe long-lived photon echo signal.",
        "positive": "Versatile sputtering technology for Al2O3 gate insulators on graphene: We report a novel fabrication method of graphene Al2O3 gate insulators based\non sputtering. Electrical performance of dual-gated mono- and bilayer\nexfoliated graphene devices is presented. Sputtered Al2O3 layers possess\ncomparable quality to oxides obtained by atomic layer deposition (ALD) with\nrespect to a high relative dielectric constant of about 8, as well as\nlow-hysteresis performance and high breakdown voltage. We observe a moderate\ncarrier mobility of about 1000 cm2/Vs in graphene and 350 cm2/Vs in its bilayer\ndue to increased resonant scattering on atomic scale defects. Most likely this\noriginated from the thin Al precursor layer evaporated prior to sputtering the\nAl2O3 gate oxide."
    },
    {
        "anchor": "Simulated annealing with time-varying strain in a dipole-coupled array\n  of magnetostrictive nanomagnets: In a two-dimensional arrangement of closely spaced elliptical nanomagnets\nwith in-plane magnetic anisotropy, whose major axes are aligned along columns\nand minor axes along rows, dipole coupling will make the magnetic ordering\n\"ferromagnetic\" along the columns and \"anti-ferromagnetic\" along the rows.\nNoise and other perturbations can drive the system out of this ground state\nconfiguration and pin it in a metastable state where the magnetization\norientations will not follow this pattern. Internal energy barriers,\nsufficiently larger than the thermal energy kT, will prevent the system from\nleaving the metastable state and decaying spontaneously to the ground state.\nThese barriers can be temporarily eroded by globally straining the nanomagnets\nwith time-varying strain if the nanomagnets are magnetostrictive, which will\nallow the system to return to ground state after strain is removed. This is a\nhardware emulation of simulated annealing in an interacting many body system.\nHere, we demonstrate this function experimentally.",
        "positive": "Quantum time-dependent Monte Carlo simulation of electron devices with\n  2D linear-band materials: a genuine TeraHertz signature for graphene: An intrinsic electron injection model for linear band two-dimensional (2D)\nmaterials, like graphene, is presented and its coupling to a recently developed\nquantum time-dependent Monte Carlo simulator for electron devices, based on the\nuse of stochastic Bohmian conditional wave functions, is explained. The\nsimulator is able to capture the full (DC, AC, transient and noise) performance\nof 2D electron devices. In particular, we demonstrate that the injection of\nelectrons with positive and negative kinetic energies is mandatory when\ninvestigating high frequency performance of linear band materials with Klein\ntunneling, while traditional models dealing with holes (defined as the lack of\nelectrons) can lead to unphysical results. We show that the number of injected\nelectrons is bias-dependent, implying that an extra charge is required to get\nself-consistent results. Interestingly, we provide a successful comparison with\nexperimental DC data. Finally, we predict that a genuine high-frequency\nsignature due to a roughly constant electron injection rate in 2D linear band\nelectron devices (which is missing in 2D parabolic band ones) can be used as a\nband structure tester."
    },
    {
        "anchor": "Chiral Stoner magnetism in Dirac bands: We argue that Stoner magnetism in bands endowed with Berry curvature is\nprofoundly influenced by the chiral interaction between Berry's orbital\nmagnetization and spin chirality density. The key effect is that carriers\nmoving in the presence of a spin texture see it as a source of a\npseudo-magnetic field coupled to their orbital motion through a chiral\nAharonov-Bohm effect. This interaction favors chiral spin textures such as\nskyrmions -- the topologically protected objects with particle-like properties,\nstabilized in the ground state. The chiral interaction softens the threshold\nfor Stoner instability, rendering chiral spin-ordered phases readily accessible\nunder realistic conditions. We illustrate this effect for a graphene multilayer\nmodel, with magnetization and pseudo-magnetic fields taking different values in\ndifferent valleys, yet the results are applicable to generic Stoner magnets.",
        "positive": "Merging Dirac points and topological phase transitions in the\n  tight-binding model on the generalized honeycomb lattice: Moving, merging and annihilating Dirac points are studied theoretically in\nthe tight-binding model on honeycomb lattice with up-to third-nearest-neighbor\nhoppings. We obtain a rich phase diagram of the topological phase transitions\nin the parameter space of direction-dependent hoppings. We obtain the\nconditions for the three Dirac points to merge and for the tricritical points.\nWe find that only very small third-nearest-neighbor hoppings are enough for the\nexistence of the merging of three-Dirac-points and the tricritical points, if\nthe system is sufficiently anisotropic. The density of states is obtained to be\n$D(\\epsilon) \\propto |\\epsilon|^{1/3}$ when three Dirac points merge, and\n$D(\\epsilon) \\propto |\\epsilon|^{1/4}$ at the tricritical points. It is\npossible to realize these topological phase transitions in the ultracold atoms\non the optical lattice, strained monolayer graphene or strained bilayer\ngraphene."
    },
    {
        "anchor": "Localized electronic states at grain boundaries on the surface of\n  graphene and graphite: Recent advances in large-scale synthesis of graphene and other 2D materials\nhave underscored the importance of local defects such as dislocations and grain\nboundaries (GBs), and especially their tendency to alter the electronic\nproperties of the material. Understanding how the polycrystalline morphology\naffects the electronic properties is crucial for the development of\napplications such as flexible electronics, energy harvesting devices or\nsensors. We here report on atomic scale characterization of several GBs and on\nthe structural-dependence of the localized electronic states in their vicinity.\nUsing low temperature scanning tunneling microscopy (STM) and spectroscopy\n(STS), together with tight binding and ab initio numerical simulations we\nexplore GBs on the surface of graphite and elucidate the interconnection\nbetween the local density of states (LDOS) and their atomic structure. We show\nthat the electronic fingerprints of these GBs consist of pronounced resonances\nwhich, depending on the relative orientation of the adjacent crystallites,\nappear either on the electron side of the spectrum or as an electron-hole\nsymmetric doublet close to the charge neutrality point. These two types of\nspectral features will impact very differently the transport properties\nallowing, in the asymmetric case to introduce transport anisotropy which could\nbe utilized to design novel growth and fabrication strategies to control device\nperformance.",
        "positive": "Phonon-limited transport coefficients in extrinsic graphene: The effect of electron-phonon scattering processes over the thermoelectric\nproperties of extrinsic graphene was studied. Electrical and thermal\nresistivity, as well as the thermopower, were calculated within the Bloch\ntheory approximations. Analytical expressions for the different transport\ncoefficients were obtained from a variational solution of the Boltzmann\nequation. The phonon-limited electrical resistivity \\rho_{e-ph} shows a linear\ndependence at high temperatures, and follows {\\rho}_{e-ph} \\sim T^{4} at low\ntemperatures, in agreement with experiments and theory previously reported in\nthe literature. The phonon-limited thermal resistivity at low temperatures\nexhibits a \\sim T dependence, and achieves a nearly constant value at high\ntemperatures. The predicted Seebeck coefficient at verylow temperatures is Q(T)\n\\sim -\\pi 2 k_B T /(3 e E_F), which shows a n^{-1/2} dependence with the\ndensity of carriers, in agreement with experimental evidence. Our results\nsuggest that thermoelectric properties can be controlled by adjusting the\nBloch-Gruneisen temperature through its dependence on the extrinsic carrier\ndensity in graphene."
    },
    {
        "anchor": "Spin-Hall effect and spin-Coulomb drag in doped semiconductors: In this review, we describe in detail two important spin-transport phenomena:\nthe extrinsic spin-Hall effect (coming from spin-orbit interactions between\nelectrons and impurities) and the spin-Coulomb drag. The interplay of these two\nphenomena is analyzed. In particular, we discuss the influence of scattering\nbetween electrons with opposite spins on the spin current and the spin\naccumulation produced by the spin-Hall effect. Future challenges and open\nquestions are briefly discussed.",
        "positive": "Magnetic order induced polarization anomaly of Raman scattering in 2D\n  magnet CrI$_3$: The recent discovery of 2D magnets has revealed various intriguing phenomena\ndue to the coupling between spin and other degree of freedoms (such as helical\nphotoluminescence, nonreciprocal SHG). Previous research on the spin-phonon\ncoupling effect mainly focuses on the renormalization of phonon frequency. Here\nwe demonstrate that the Raman polarization selection rules of optical phonons\ncan be greatly modified by the magnetic ordering in 2D magnet CrI$_3$. For\nmonolayer samples, the dominant A$\\rm_{1g}$ peak shows abnormally high\nintensity in the cross polarization channel at low temperature, which is\nforbidden by the selection rule based on the lattice symmetry. While for\nbilayer, this peak is absent in the cross polarization channel for the layered\nantiferromagnetic (AFM) state and reappears when it is tuned to the\nferromagnetic (FM) state by an external magnetic field. Our findings shed light\non exploring the emergent magneto-optical effects in 2D magnets."
    },
    {
        "anchor": "Phenomenological theory of magnetization reversal in nanosystems with\n  competing anisotropies: The interplay between intrinsic and surface/interface-induced magnetic\nanisotropies strongly in- fluences magnetization processes in nanomagnetic\nsystems. We develop a micromagnetic theory to describe the field-driven\nreorientation in nanomagnets with cubic and uniaxial anisotropies. Spin\nconfigurations in competing phases and parameters of accompanying multidomain\nstates are calculated as functions of the applied field and the magnetic\nanisotropies. The constructed magnetic phase diagrams allow to classify\ndifferent types of the magnetization reversal and to provide detailed analysis\nof the switching processes in magnetic nanostructures. The calculated\nmagnetization profiles of isolated domain walls show that the equilibrium\nparameters of such walls are extremely sensitive to applied magnetic field and\nvalues of the competing anisotropies and can vary in a broad range. For\nnanolayers with perpendicular anisotropy the geometrical parameters of stripe\ndomains have been calculated as functions of a bias field. The results are\napplied to analyse the magnetization processes as observed in various\nnanosystems with competing anisotropies, mainly, in diluted magnetic\nsemiconductor films (Ga,Mn)As.",
        "positive": "Partially coherent electron transport in terahertz quantum cascade\n  lasers based on a Markovian master equation for the density matrix: We derive a Markovian master equation for the single-electron density matrix,\napplicable to quantum cascade lasers (QCLs). The equation conserves the\npositivity of the density matrix, includes off-diagonal elements (coherences)\nas well as in-plane dynamics, and accounts for electron scattering with phonons\nand impurities. We use the model to simulate a terahertz-frequency QCL, and\ncompare the results with both experiment and simulation via nonequilibrium\nGreen's functions (NEGF). We obtain very good agreement with both experiment\nand NEGF when the QCL is biased for optimal lasing. For the considered device,\nwe show that the magnitude of coherences can be a significant fraction of the\ndiagonal matrix elements, which demonstrates their importance when describing\nTHz QCLs. We show that the in-plane energy distribution can deviate far from a\nheated Maxwellian distribution, which suggests that the assumption of\nthermalized subbands in simplified density-matrix models is inadequate. We also\nshow that the current density and subband occupations relax towards their\nsteady-state values on very different time scales."
    },
    {
        "anchor": "Phonon-mediated Hydrodynamic Transport in a Weyl Semimetal: We analyze from a microscopic point of view the feasibility of a hydrodynamic\nregime in a type-I Weyl semimetal driven by electron-electron interactions\nmediated by virtual phonons. Considering also the effects of of impurities and\nthe absorption/emission of real phonons, the electric and thermal\nconductivities are derived. At temperatures $T$ above the Bloch-Gr\\\"uneisen\ntemperature $T_\\textrm{BG}$, virtual phonons behave similarly to real phonons,\nbut the Lorenz ratio is modified by a constant prefactor dependent on the Fermi\nsurface geometry. For temperatures below $T_\\textrm{BG}$, processes that do not\nconserve chirality induce a $T^2$ dependence in the electric resistivity,\nopening a window where momentum-conserving interactions dominate transport\nsignatures. We quantitatively discuss this hydrodynamic window and put it into\ncontext with recent experimental literature on the subject.",
        "positive": "Physical insight into reduced surface roughness scattering in strained\n  silicon inversion layers: A seemingly anomalous enhancement of electron mobility in strained silicon\ninversion layers at high sheet densities has exposed a conspicuous gap between\ndevice physics theory and experiment in recent years. We show that the root of\nthis discrepancy is due to a bulging effect in the electron \\Delta 4\nwavefunction at the silicon surface. This renders \\Delta 4 electrons more\nsusceptible to perturbations in surface structure thereby increasing surface\nroughness scattering for these states. Strain engineering utilized by the CMOS\nindustry reduces the relative occupancy of the \\Delta 4 states resulting in\nless overall surface roughness scattering in the channel. We show that the\norigin of this effect can be explained by moving beyond the effective mass\napproximation and contrasting the properties of the \\Delta 2 and \\Delta 4\nwavefunctions in a representation that comprehends full crystal and Bloch state\nsymmetry."
    },
    {
        "anchor": "Build-up of Vibron-Mediated Electron Correlations in Molecular Junctions: We investigate on the same footing the time-dependent electronic transport\nproperties and vibrational dynamics of a molecular junction. We show that\nfluctuations of both the molecular vibron displacement and the electronic\ncurrent across the junction undergo damped oscillations towards the\nsteady-state. We assign the former to the onset of electron tunneling events\nassisted by vibron-emission. The time-dependent build-up of electron-hole\ncorrelations is revealed as a departure of the charge-transfer statistics from\nthe generalized-binomial one after a critical time tc. The phonon-back action\non the tunneling electrons is shown to amplify and accelerate this build-up\nmechanism.",
        "positive": "Vector, Bidirector and Bloch Skyrmion Phases Induced by Structural\n  Crystallographic Symmetry Breaking: The 212 species of structural phase transitions which break macroscopic\nsymmetry are analyzed with respect to the occurrence of time-reversal invariant\nvector and bidirector order parameters. The possibility of discerning the\norientational domain states of the low-symmetry phase by these `vectorlike'\nphysical properties has been derived using a computer algorithm exploiting the\nconcept of polar, axial, chiral and neutral dipoles. It is argued that for\nspecies 32 > 3, 422 > 4 and 622 > 6, Bogdanov-Yablonskii phenomenological\ntheory for a ferromagnetic Bloch Skyrmions applies also to the ferroelectric\nBloch Skyrmions. In these fully-ferroelectric and nonferroelastic species, the\nGinzburg Landau functional allows a pseudo-Lifshitz invariant of chiral\nbidirector symmetry, analogous to the chiral Dzyaloshinskii-Moria term assumed\nin magnetic Bloch Skyrmion theory."
    },
    {
        "anchor": "Scattering Theory of Nonlinear Thermoelectricity in Quantum Coherent\n  Conductors: We construct a scattering theory of weakly nonlinear thermoelectric transport\nthrough sub-micron scale conductors. The theory incorporates the leading\nnonlinear contributions in temperature and voltage biases to the charge and\nheat currents. Because of the finite capacitances of sub-micron scale\nconducting circuits, fundamental conservation laws such as gauge invariance and\ncurrent conservation require special care to be preserved. We do this by\nextending the approach of Christen and B\\\"uttiker [Europhys. Lett. 35, 523\n(1996)] to coupled charge and heat transport. In this way we write relations\nconnecting nonlinear transport coefficients in a manner similar to Mott's\nrelation between the linear thermopower and the linear conductance. We derive\nsum rules that nonlinear transport coefficients must satisfy to preserve gauge\ninvariance and current conservation. We illustrate our theory by calculating\nthe efficiency of heat engines and the coefficient of performance of\nthermoelectric refrigerators based on quantum point contacts and resonant\ntunneling barriers. We identify in particular rectification effects that\nincrease device performance.",
        "positive": "Observation of decoherence in a carbon nanotube mechanical resonator: In physical systems, decoherence can arise from both dissipative and\ndephasing processes. In mechanical resonators, the driven frequency response\nmeasures a combination of both, while time domain techniques such as ringdown\nmeasurements can separate the two. Here, we report the first observation of the\nmechanical ringdown of a carbon nanotube mechanical resonator. Comparing the\nmechanical quality factor obtained from frequency- and time-domain\nmeasurements, we find a spectral quality factor four times smaller than that\nmeasured in ringdown, demonstrating dephasing-induced decoherence of the\nnanomechanical motion. This decoherence is seen to arise at high driving\namplitudes, pointing to a non-linear dephasing mechanism. Our results highlight\nthe importance of time-domain techniques for understanding dissipation in\nnano-mechanical resonators, and the relevance of decoherence mechanisms in\nnanotube mechanics."
    },
    {
        "anchor": "Quantum and classical localisation, the spin quantum Hall effect and\n  generalisations: We consider network models for localisation problems belonging to symmetry\nclass C. This symmetry class arises in a description of the dynamics of\nquasiparticles for disordered spin-singlet superconductors which have a\nBogoliubov - de Gennes Hamiltonian that is invariant under spin rotations but\nnot under time-reversal. Our models include but also generalise the one studied\npreviously in the context of the spin quantum Hall effect. For these systems we\nexpress the disorder-averaged conductance and density of states in terms of\nsums over certain classical random walks, which are self-avoiding and have\nattractive interactions. A transition between localised and extended phases of\nthe quantum system maps in this way to a similar transition for the classical\nwalks. In the case of the spin quantum Hall effect, the classical walks are the\nhulls of percolation clusters, and our approach provides an alternative\nderivation of a mapping first established by Gruzberg, Read and Ludwig, Phys.\nRev. Lett. 82, 4254 (1999).",
        "positive": "A semi-analytical model of Bilayer Graphene Field Effect Transistor: Bilayer graphene has the very interesting property of an energy gap tunable\nwith the vertical electric field. We propose an analytical model for a\nbilayer-graphene field-effect transistor, suitable for exploring the design\nparameter space and to find a device structure with promising performance in\nterms of transistor operation. Our model, based on the effective mass\napproximation and ballistic transport assumptions, takes into account\nbilayer-graphene tunable gap and self polarization, and includes all\nband-to-band tunneling current components, which are shown to represent the\nmajor limitation to transistor operation, because the limited achievable energy\ngap is not sufficient to obtain a large Ion/Ioff ratio."
    },
    {
        "anchor": "Thermal light emission from monolayer MoS2: Because of their strong excitonic photoluminescence (PL) and\nelectroluminescence (EL), together with an excellent electronic tunability,\ntransition metal dichalcogenide (TMD) semiconductors are promising candidates\nfor novel optoelectronic devices. In recent years, several concepts for light\nemission from two-dimensional (2D) materials have been demonstrated. Most of\nthese concepts are based on the recombination of electrons and holes in a\npn-junction, either along the lateral direction using split-gate geometries in\ncombination with monolayer TMDs, or by precisely stacking different 2D\nsemiconductors on top of each other, in order to fabricate vertical van der\nWaals heterostructures, working as light-emitting diodes (LEDs). Further, EL\nwas also observed along the channel of ionic liquid gated field-effect\ntransistors (FETs) under ambipolar carrier injection. Another mechanism, which\nhas been studied extensively in carbon nanotubes (CNTs) and more recently also\nin graphene, is thermal light emission as a result of Joule heating. Although\nthe resulting efficiencies are smaller than that of LEDs based on ambipolar\nelectron-hole injection, these experiments provide valuable insights into\nmicroscopic processes, such as electron-phonon and phonon-phonon interactions,\nand the behavior of low-dimensional materials under strong bias in general.",
        "positive": "Spontaneous cross-section field in impurity graphene: It was found that the spontaneous electric field can occur in doped graphene\nin an external dc electric field. The direction of the spontaneous field is\nperpendicular to the applied field. This effect can be connected with the\nnonequilibrium electron subsystem of graphene. It was also shown up the\ninfluence of problem parameters on the characteristics of the spontaneous\nfield."
    },
    {
        "anchor": "Magnetic translation groups as group extension: Extensions of a direct product T of two cyclic groups Z_n1 and Z_n2 by an\nAbelian (gauge) group G with the trivial action of T on G are considered. All\npossible (nonequivalent) factor systems are determined using the Mac Lane\nmethod. Some of resulting groups describe magnetic translation groups. As\nexamples extensions with G=U(1) and G=Z_n are considered and discussed.",
        "positive": "Effect of [OH-] linkages on luminescent properties of ZnO nanoparticles: Optical properties of ZnO nanoparticles prepared from a simple chemical\nmethod using sodium zincate bath show strong white light emission. X-ray\nabsorption fine structure studies reveal a completely different local\nenvironment around Zn in these ZnO nanoparticles. The observed luminescence\nproperties and local structural changes have been explained on the basis of a\nlinkage between Zn and OH- ions in the surface layers of ZnO nanoparticles."
    },
    {
        "anchor": "Negative free carrier absorption in terahertz quantum cascade lasers: We analyze the peculiar case where the free carrier absorption arising from\nLO phonon absorption-assisted transitions becomes negative and therefore turns\ninto a gain source for quantum cascade lasers. Such an additional source of\ngain exists when the ratio between the electronic and the lattice temperatures\nis larger than one, a condition that is usually fulfilled in quantum cascade\nlasers. We find a gain of few cm$^{-1}$'s at 200K. We report the development of\na terahertz quantum cascade laser operating in the negative free carrier\nabsorption regime.",
        "positive": "Role of non-collinear magnetization: from ferromagnetic nano wires to\n  quantum rings: We consider interaction effects related to a nonuniform magnetization in\nferromagnetic nanowires and their possible generalization to nanorings. First\nwe show that the electric current in a ferromagnetic nanowire with more than\none domain wall induces an exchange coupling between the walls mediated by the\nspin-dependent interference of scattered carriers. This interaction reveals a\ncomplex behavior as a function of mutual orientations and separation of the\ndomain walls, thus affecting the domain wall dynamics. Then we consider how the\ntheory should be modified in the case of a magnetized quantum ring. In this\ncase the situation is more complicated because the vortex and onion\nmagnetization states in the ring are not truly ferromagnetic."
    },
    {
        "anchor": "Single charge and exciton dynamics probed by molecular-scale-induced\n  electroluminescence: Excitons and their constituent charge carriers play the central role in\nelectroluminescence mechanisms determining the ultimate performance of organic\noptoelectronic devices. The involved processes and their dynamics are often\nstudied with time-resolved techniques limited by spatial averaging that\nobscures the properties of individual electron-hole pairs. Here we overcome\nthis limit and characterize single charge and exciton dynamics at the nanoscale\nby using time-resolved scanning tunnelling microscopy-induced luminescence\n(TR-STML) stimulated with nanosecond voltage pulses. We use isolated defects in\nC$_{60}$ thin films as a model system into which we inject single charges and\ninvestigate the formation dynamics of a single exciton. Tuneable hole and\nelectron injection rates are obtained from a kinetic model that reproduces the\nmeasured electroluminescent transients. These findings demonstrate that TR-STML\ncan track dynamics at the quantum limit of single charge injection and can be\nextended to other systems and materials important for nanophotonic devices.",
        "positive": "Vibrational effects in the linear conductance of carbon nanotubes: We study the influence of structural lattice fluctuations on the elastic\nelectron transport in single-wall carbon nanotubes within a\ndensity-functional-based scheme. In the linear response regime, the linear\nconductance is calculated via configurational averages over the distorted\nlattice. Results obtained from a frozen-phonon approach as well as from\nmolecular dynamics simulations are compared. We further suggest that the effect\nof structural fluctuations can be qualitatively captured by the Anderson model\nwith bond disorder. The influence of individual vibrational modes on the\nelectronic transport is discussed as well as the role of zero-point\nfluctuations."
    },
    {
        "anchor": "The Role of Oligomeric Gold-Thiolate Units in Single Molecule Junc-tions\n  of Thiol-Anchored Molecules: Using the break junction (BJ) technique we show that Au(RS)2 units play a\nsignificant role in thiol-terminated molecular junctions formed on gold. We\nhave studied a range of thiol-terminated compounds, either with the sulfur\natoms in direct conjugation with a phenyl core, or bonded to saturated\nmethylene groups. For all molecules we observe at least two distinct groups of\nconductance plateaus. By a careful analysis of the length behavior of these\nplateaus, comparing the behavior across the different cores and with methyl\nsulfide anchor groups, we demonstrate that the lower conductance groups\ncorrespond to the incorporation of Au(RS)2 oligomeric units at the contacts.\nThese structural motifs are found on the surface of gold nanoparticles but they\nhave not before been shown to exist in molecular-break junctions. The results,\nwhile exemplifying the complex nature of thiol chemistry on gold, moreover\nclarify the conductance of 1,4-benzenedithiol on gold. We show that true\nAu-S-Ph-S-Au junctions have a relatively narrow conductance distribution.",
        "positive": "Topological crystalline protection in a photonic system: Topological crystalline insulators are a class of materials with a bulk\nenergy gap and edge or surface modes, which are protected by crystalline\nsymmetry, at their boundaries. They have been realized in electronic systems:\nin particular, in SnTe. In this work, we propose a mechanism to realize\nphotonic boundary states topologically protected by crystalline symmetry. We\nmap this one-dimensional system to a two-dimensional lattice model with\nopposite magnetic fields, as well as opposite Chern numbers in its even and odd\nmirror parity subspaces, thus corresponding to a topological mirror insulator.\nFurthermore, we test how sensitive and robust edge modes depend on their mirror\nparity by performing time dependent evolution simulation of edge modes in a\nphotonic setting with realistic experimental parameters."
    },
    {
        "anchor": "Electronic structure, magnetoexcitons and valley polarized electron gas\n  in 2D crystals: We describe here recent work on the electronic properties, magnetoexcitons\nand valley polarised electron gas in 2D crystals. Among 2D crystals, monolayer\n$MoS_2$ has attracted significant attention as a direct-gap 2D semiconductor\nanalogue of graphene. The crystal structure of monolayer $MoS_2$ breaks\ninversion symmetry and results in K valley selection rules allowing to address\nindividual valleys optically. Additionally, the band nesting near Q points is\nresponsible for enhancing the optical response of $MoS_2$.We show that at low\nenergies the electronic structure of $MoS_2$ is well approximated by the\nmassive Dirac Fermion model. We focus on the effect of magnetic field on\noptical properties of $MoS_2$. We discuss the Landau level structure of massive\nDirac fermions in the two non-equivalent valleys and resulting valley Zeeman\nsplitting. The effects of electron-electron interaction on the valley Zeeman\nsplitting and on the magneto-exciton spectrum are described. We show the\nchanges in the absorption spectrum as the self-energy, electron-hole exchange\nand correlation effects are included. Finally, we describe the valley-polarised\nelectron gas in $WS_2$ and its optical signature in finite magnetic fields.",
        "positive": "Thermal transport in compensated semimetals: a mystery explained: It is well known that the electronic thermal conductivity of clean\ncompensated semimetals can be greatly enhanced over the electric conductivity\nby the availability of an ambipolar mechanism of conduction, whereby electrons\nand holes flow in the same direction experiencing negligible Coulomb scattering\nas well as negligible impurity scattering. This enhancement -- resulting in a\nbreakdown of the Wiedemann-Franz law with an anomalously large Lorenz ratio --\nhas been recently observed in two-dimensional monolayer and bilayer graphene\nnear the charge neutrality point. In contrast to this, three-dimensional\ncompensated semimetals such as WP$_2$ and Sb are typically found to show a\nreduced Lorenz ratio. This dramatic difference in behavior is generally\nattributed to different regimes of Fermi statistics in the two cases:\ndegenerate electron-hole liquid in compensated semimetals versus non-degenerate\nelectron-hole liquid in graphene. We show that this difference is not\nsufficient to explain the reduction of the Lorenz ratio in compensated\nsemimetals. We argue that the solution of the puzzle lies in the ability of\ncompensated semimetals to sustain sizeable regions of electron-hole\naccumulation near the contacts, which in turn is a consequence of the large\nseparation of electron and hole pockets in momentum space. These accumulations\nsuppress the ambipolar conduction mechanism and effectively split the system\ninto two independent electron and hole conductors. We present a quantitative\ntheory of the crossover from ambipolar to unipolar conduction as a function of\nthe size of the electron-hole accumulation regions, and show that it naturally\nleads to a sample-size-dependent thermal conductivity."
    },
    {
        "anchor": "Mechanical Resonators for Quantum Optomechanics Experiments at Room\n  Temperature: All quantum optomechanics experiments to date operate at cryogenic\ntemperatures, imposing severe technical challenges and fundamental constraints.\nHere we present a novel design of on-chip mechanical resonators which exhibit\nfundamental modes with frequencies $f$ and mechanical quality factors\n$Q_\\mathrm{m}$ sufficient to enter the optomechanical quantum regime at room\ntemperature. We overcome previous limitations by designing ultrathin,\nhigh-stress silicon nitride (Si$_3$N$_4$) membranes, with tensile stress in the\nresonators' clamps close to the ultimate yield strength of the material. By\npatterning a photonic crystal on the SiN membranes, we observe reflectivities\ngreater than 99%. These on-chip resonators have remarkably low mechanical\ndissipation, with $Q_\\mathrm{m}$$\\sim$$10^8$, while at the same time exhibiting\nlarge reflectivities. This makes them a unique platform for experiments towards\nthe observation of massive quantum behavior at room temperature.",
        "positive": "Magnetoresistive sensors based on the elasticity of domain walls: Magnetic sensors based on the magnetoresistance effects have a promising\napplication prospect due to their excellent sensitivity and advantages in terms\nof the integration. However, competition between higher sensitivity and larger\nmeasuring range remains a problem. Here, we propose a novel mechanism for the\ndesign of magnetoresistive sensors: probing the perpendicular field by\ndetecting the expansion of the elastic magnetic Domain Wall (DW) in the free\nlayer of a spin valve or a magnetic tunnel junction. Performances of devices\nbased on this mechanism, such as the sensitivity and the measuring range can be\ntuned by manipulating the geometry of the device, without changing the\nintrinsic properties of the material, thus promising a higher integration level\nand a better performance. The mechanism is theoretically explained based on the\nexperimental results. Two examples are proposed and their functionality and\nperformances are verified via micromagnetic simulation."
    },
    {
        "anchor": "RKKY Interaction On Surfaces of Topological Insulators With\n  Superconducting Proximity Effect: We consider the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between\nmagnetic impurities on the surface of a three-dimensional topological insulator\nwith proximity induced superconductivity. A superconductor placed on the top of\nthe topological insulator induces a gap in the surface electron states and\ngives rise to a long-ranged in-plane antiferromagnetic RKKY interaction. This\ninteraction is frustrated due to strong spin-orbit coupling, decays as $1/r$\nfor $r<\\xi$, where $r$ is the distance between two magnetic impurities and\n$\\xi$ the superconducting coherence length, and dominates over the\nferromagnetic and Dzyaloshinskii-Moriya type interactions for $r>\\xi$. We find\nthe condition for the Yu-Shiba-Rusinov intragap states that are bound to the\nmagnetic impurities.",
        "positive": "Nanoscale Detection of Magnon Excitations with Variable Wavevectors\n  Through a Quantum Spin Sensor: We report the optical detection of magnons with a broad range of wavevectors\nin magnetic insulator Y3Fe5O12 thin films by proximate nitrogen-vacancy (NV)\nsingle-spin sensors. Through multi-magnon scattering processes, the excited\nmagnons generate fluctuating magnetic fields at the NV electron spin resonance\nfrequencies, which accelerate the relaxation of NV spins. By measuring the\nvariation of the emitted spin-dependent photoluminescence of the NV centers,\nmagnons with variable wavevectors up to ~ 5 x 10^7 m-1 can be optically\naccessed, providing an alternative perspective to reveal the underlying spin\nbehaviors in magnetic systems. Our results highlight the significant\nopportunities offered by NV single-spin quantum sensors in exploring nanoscale\nspin dynamics of emergent spintronic materials."
    },
    {
        "anchor": "Matter-Wave Solitons in an F=1 Spinor Bose-Einstein Condensate: Following our previous work [J. Ieda, T. Miyakawa, M. Wadati,\ncond-mat/0404569] on a novel integrable model describing soliton dynamics of an\nF=1 spinor Bose--Einstein condensate, we discuss in detail the properties of\nthe multi-component system with spin-exchange interactions. The exact multiple\nbright soliton solutions are obtained for the system where the mean-field\ninteraction is attractive (c_0 < 0) and the spin-exchange interaction is\nferromagnetic (c_2 < 0). A complete classification of the one-soliton solution\nwith respect to the spin states and an explicit formula of the two-soliton\nsolution are presented. For solitons in polar state, there exists a variety of\ndifferent shaped solutions including twin peaks. We show that a \"singlet pair\"\ndensity can be used to distinguish those energetically degenerate solitons. We\nalso analyze collisional effects between solitons in the same or different spin\nstate(s) by computing the asymptotic forms of their initial and final states.\nThe result reveals that it is possible to manipulate the spin dynamics by\ncontrolling the parameters of colliding solitons.",
        "positive": "Orbital magnetic moments in pure and doped carbon nanotubes: The unusual band structure of carbon nanotubes (CNs) results in their\nremarkable magnetic properties. The application of magnetic field parallel to\nthe tube axis can change the conducting properties of the CN from metallic to\nsemiconducting and vice versa. Apart from that B induces (via the Bohm-Aharonov\neffect) orbital magnetic moments $\\mu_{orb}$ in the nanotube. These moments are\nstudied both in pure and hole- or electron-doped CNs, isolated or in a circuit.\nRemarkably, $\\mu_{orb}$ in pure CNs depends uniquely on their original\nconducting properties, length, and temperature, but it does not depend on the\nnanotube radius or the particular chirality. In doped nanotubes the magnetic\nmoments can be strongly altered and depend on the radius and\nchirality.Temperature can even change their character from diamagnetic at low T\nto paramagnetic at high T. A full electron-hole symmetry in doped tubes is also\nrevealed."
    },
    {
        "anchor": "Observation of field emission from GeSn nanoparticles epitaxially grown\n  on silicon nanopillar arrays: We apply molecular beam epitaxy to grow GeSn-nanoparticles on top of\nSi-nanopillars patterned onto p-type Si wafers. We use X-ray photoelectron\nspectroscopy to confirm a metallic behavior of the nanoparticle surface due to\npartial Sn segregation as well as the presence of a superficial Ge oxide. We\nreport the observation of stable field emission current from the\nGeSn-nanoparticles. We prove that field emission can be enhanced by preventing\nGeSn nanoparticles oxidation or by breaking the oxide layer through electrical\nstress. Finally, we show that GeSn/p-Si junctions have a rectifying behavior.",
        "positive": "DNA-decorated graphene chemical sensors: Graphene is a true two dimensional material with exceptional electronic\nproperties and enormous potential for practical applications. Graphene's\npromise as a chemical sensor material has been noted but there has been\nrelatively little work on practical chemical sensing using graphene, and in\nparticular how chemical functionalization may be used to sensitize graphene to\nchemical vapors. Here we show one route towards improving the ability of\ngraphene to work as a chemical sensor by using single stranded DNA as a\nsensitizing agent. The resulting broad response devices show fast response\ntimes, complete and rapid recovery to baseline at room temperature, and\ndiscrimination between several similar vapor analytes."
    },
    {
        "anchor": "Effects of Si solute on the glass formation and atomic structure of Pd\n  liquid: Molecular dynamics simulations were performed to study the effects of Si\nsolute on the glass formation and crystallization of Pd liquid. Pure Pd sample\nprepared by quenching process with cooling rate of $10^{13}$ K/s can be in an\namorphous state but the structural analysis indicates there is nearly no\nglass-forming motif in the sample. However, doping a small amount Si (Si\nconcentration ~ 4%) the sample can be vitrified at a cooling rate of $10^{12}$\nK/s. The glass-forming motifs such as Pd-centered Z13, Si-centered Z9-like and\nMixed-ICO-Cube clusters with 5-fold local symmetry are found to be the dominant\nshort-range orders in the glassy samples. With the increasing of the Si-doping\nconcentration, these glass-forming motifs tend to aggregate and connect with\neach other forming a network structure. Our calculated results revealed that Si\nsolutes in liquid Pd can significantly enhance the glass-forming ability.",
        "positive": "Instabilities Toward Charge Density Wave and Paired Quantum Hall State\n  of Half-Filled Landau Levels: We study the stability of spin-resolved Landau levels at electron filling\nfactor $\\nu=n+1/2$, where n is a positive integer. Representing the half-filled\ntopmost Landau level by fermions and the n filled inner Landau levels by n\nbosons, coupled to the Chern-Simons gauge fields, we show that the ground\nstates exhibit charge density wave order for $n(n+1/2)>15.54 \\pi(a_B^*)^2 n_e$,\nwhere $n_e$ is the 2D carrier density and $a_B^*$ is the effective Bohr radius.\nWe find that the pairing interaction mediated by the fluctuating gauge field is\nenhanced near the charge density wave instability such that p-wave pairing of\nthe Chern-Simons fermions prevails for\n$3.49(\\pi{\\ab}^2)n_e<n^2(n+1/2)<20.22\\pi(a_B^*)^2 n_e$. The competition between\ncharge density wave order and paired quantum Hall state is discussed in\nconnection to recent experiments."
    },
    {
        "anchor": "Termination Dependent Topological Surface States in Nodal Loop Semimetal\n  HfP2: Symmetry plays a major role in all disciplines of physics. Within the field\nof topological materials there is a great interest in understanding how the\nmechanics of crystalline and internal symmetries protect crossings between the\nconduction and valence bands. Additionally, exploring this direction can lead\nto a deeper understanding on the topological properties of crystals hosting a\nvariety of symmetries. For the first time, we report the experimental\nobservation of topological surface states in the nodal loop semimetal HfP2\nusing angle resolved photoemission spectroscopy (ARPES) which is supported by\nour first principles calculations. Our study shows termination dependent\nsurface states in this compound. Our experimental data reveal surface states\nlinked to three unique nodal loops confirmed by theoretical calculation to be\ntopologically non-trivial. This work demonstrates that transition metal\ndipnictides provide a good platform to study non-trivial topological states\nprotected by nonsymmorphic symmetry.",
        "positive": "The type II Weyl semimetals at low temperatures: chiral anomaly, elastic\n  deformations, zero sound: We consider the properties of the type II Weyl semimetals at low temperatures\nbasing on the particular tight - binding model. In the presence of electric\nfield directed along the line connecting the Weyl points of opposite chirality\nthe occupied states flow along this axis giving rise to the creation of\nelectron - hole pairs. The electrons belong to a vicinity of one of the two\ntype II Weyl points while the holes belong to the vicinity of the other. This\nprocess may be considered as the manifestation of the chiral anomaly that\nexists without any external magnetic field. It may be observed experimentally\nthrough the measurement of conductivity. Next, we consider the modification of\nthe theory in the presence of elastic deformations. In the domain of the\nconsidered model, where it describes the type I Weyl semimetals the elastic\ndeformations lead to the appearance of emergent gravity. In the domain of the\ntype II Weyl semimetals the form of the Fermi surface is changed due to the\nelastic deformations, and its fluctuations represent the special modes of the\nzero sound. We find that there is one - to one correspondence between them and\nthe sound waves of the elasticity theory. Next, we discuss the influence of the\nelastic deformations on the conductivity. The particularly interesting case is\nwhen our model describes the intermediate state between the type I and the type\nII Weyl semimetal. Then without the elastic deformations there are the Fermi\nlines instead of the Fermi points/Fermi surface, while the DC conductivity\nvanishes. However, even small elastic deformations may lead to the appearance\nof large conductivity."
    },
    {
        "anchor": "Decoherence and relaxation of a single electron in a one dimensional\n  conductor: We study the decoherence and relaxation of a single elementary electronic\nexcitation propagating in a one-dimensional chiral conductor. Using\ntwo-particle interferences in the electronic analog of the Hong-Ou-Mandel\nexperiment, we analyze quantitatively the decoherence scenario of a single\nelectron propagating along a quantum Hall edge channel at filling factor 2. The\ndecoherence results from the emergence of collective neutral excitations\ninduced by Coulomb interaction and leading, in one dimension, to the\ndestruction of the elementary quasiparticle. This study establishes the\nrelevance of electron quantum optics setups to provide stringent tests of\nstrong interaction effects in one-dimensional conductors described by Luttinger\nliquids paradigm.",
        "positive": "Few-layer Phosphorene: An Ideal 2D Material For Tunnel Transistors: 2D transition metal dichalcogenides (TMDs) have attracted a lot of attention\nrecently for energy-efficient tunneling-field-effect transistor (TFET)\napplications due to their excellent gate control resulting from their\natomically thin dimensions. However, most TMDs have bandgaps (Eg) and effective\nmasses (m*) outside the optimum range needed for high performance. It is shown\nhere that the newly discovered 2D material, few-layer phosphorene, has several\nproperties ideally suited for TFET applications: 1) direct Eg in the optimum\nrange ~1.0-0.4 eV, 2) light transport m* (0.15m0), 3) anisotropic m* which\nincreases the density of states near the band edges, and 4) a high mobility.\nThese properties combine to provide phosphorene TFET outstanding ION 1 mA/um,\nON/OFF ratio~1e6, scalability to 6 nm channel length and 0.2 V supply voltage,\nthereby significantly outperforming the best TMD-TFETs in energy-delay\nproducts. Full-band atomistic quantum transport simulations establish\nphosphorene TFETs as serious candidates for energy-eficient and scalable\nreplacements of MOSFETs."
    },
    {
        "anchor": "Probing Quantitatively Two-electron Entanglement with a Spintronic\n  Quantum Eraser: We design an ingenious spintronic quantum eraser to quantitatively probe the\ntwo-electron entanglement. It is shown that the concurrence of two\nspin-entangled electrons is directly given by the Aharonov-Bohm oscillation\namplitude of the Fano factor, a measurable current-current correlation, making\nit rather promising to experimentally quantify the two-electron entanglement.\nThe singlet and triplet entangled states are distinguished by the opposite\nsigns in the Fano factor. Since the main building blocks in the designed setup,\nan electronic Mach-Zehnder interferometer and a spin filter, have already been\nimplemented, our proposal is particularly pertinent to experiments.",
        "positive": "Photovoltaic Chiral Magnetic Effect: We theoretically predict a generation of a current in Weyl semimetals by\napplying circularly polarized light. The electric field of the light can drive\nan effective magnetic field of order of ten Tesla. For lower frequency light, a\nnon-equilibrium spin distribution is formed near the Fermi surface. Due to the\nspin-momentum locking, a giant electric current proportional to the effective\nmagnetic field is induced. On the other hand, higher frequency light realizes a\nquasi-static Floquet state with no induced electric current. We discuss\nrelevant materials and estimate order of magnitude of the induced current."
    },
    {
        "anchor": "Magnon spin transport around the compensation magnetic field in\n  easy-plane antiferromagnetic insulators: In this work, we theoretically study the magnon spin transport in easy-plane\nantiferromagnetic insulators in the presence of an in-plane magnetic field. By\nexactly calculating the magnon spectrum, we find the band splitting due to the\nmagnetic anisotropy can be fully compensated by the external field at a\nparticular strength, which makes its dynamics nearly equivalent to an easy-axis\nantiferromagnet. As a result, the intrinsic magnon spin Hall effect due to the\ndipole-dipole interaction, previously predicted in easy-axis antiferromagnets\nis activated in easy-plane antiferromagnets. The compensation feature also\nallows the field control of magnon spin lifetime and hence the spin diffusion\nlength. The compensation feature is robust against the biaxial anisotropy.",
        "positive": "Coherent control of defect spins in silicon carbide above 550 K: Great efforts have been made to the investigation of defects in silicon\ncarbide for their attractive optical and spin properties. However, most of the\nresearches are implemented at low and room temperature. Little is known about\nthe spin coherent property at high temperature. Here, we experimentally\ndemonstrate coherent control of divacancy defect spins in silicon carbide above\n550 K. The spin properties of defects ranging from room temperature to 600 K\nare investigated, in which the zero-field-splitting is found to have a\npolynomial temperature dependence and the spin coherence time decreases as the\ntemperature increases. Moreover, as an example of application, we demonstrate a\nthermal sensing using the Ramsey method at about 450 K. Our experimental\nresults would be useful for the investigation of high temperature properties of\ndefect spins and silicon carbide-based broad-temperature range quantum sensing."
    },
    {
        "anchor": "Quantifying the complex permittivity and permeability of magnetic\n  nanoparticles: The complex permittivity and permeability of superparamagnetic iron-oxide\nnanoparticles has been quantified using a circular waveguide assembly with a\nstatic magnetic field to align the nanoparticle's magnetization. The high\nsensitivity of the measurement provides the precise resonant feature of\nnanoparticles. The complex permeability in the vicinity of ferromagnetic\nresonance (FMR) is in agreement with the nanoparticle's measured magnetization\nvia conventional magnetometry. A rigorous and self-consistent measure of\ncomplex permittivities and permeabilities of nanoparticles is crucial to\nascertain accurately the dielectric behaviour as well as the frequency response\nof nanoparticle magnetization, necessary ingredients when designing and\noptimizing magnetic nanoparticles for biomedical applications.",
        "positive": "Charge transfer statistics and entanglement in normal-quantum\n  dot-superconductor hybrid structures: We analyze the full counting statistics (FCS) of a single-site quantum dot\ncoupled to multiple metallic electrodes in the normal state and a\nsuperconductor for arbitrary transmission. We present an analytical solution of\nthe problem taking into account the full energy dependence of the transmission\ncoefficient. We identify two transport processes as sources of entanglement\nbetween the current carriers by observing positive cross current correlations.\nFurthermore, we consider ferromagnetic electrodes and show how they can be used\nas detectors in experiments violating the Bell-Clauser-Horne-Shimony-Holt\ninequality."
    },
    {
        "anchor": "Thermoelectric efficiency of three-terminal quantum thermal machines: The efficiency of a thermal engine working in linear response regime in a\nmulti-terminals configuration is discussed. For the generic three-terminal\ncase, we provide a general definition of local and non-local transport\ncoefficients: electrical and thermal conductances, and thermoelectric powers.\nWithin the Onsager formalism, we derive analytical expressions for the\nefficiency at maximum power, which can be written in terms of generalized\nfigures of merit. Also, using two examples, we investigate numerically how a\nthird terminal could improve the performance of a quantum system, and under\nwhich conditions non-local thermoelectric effects can be observed.",
        "positive": "Numerical simulation of the thermal fragmentation process in fullerene\n  C60: The processes of defect formation and annealing in fullerene C60 at\nT=(4000-6000)K are studied by the molecular dynamics technique with a\ntight-binding potential. The cluster lifetime until fragmentation due to the\nloss of a C2 dimer has been calculated as a function of temperature. The\nactivation energy and the frequency factor in the Arrhenius equation for the\nfragmentation rate have been found to be Ea = (9.2 +- 0.4) eV and A = (8 +-\n1)10^{19} 1/s. It is shown that fragmentation can occur after the C60 cluster\nloses its spherical shape. This fact must be taken into account in theoretical\ncalculations of Ea."
    },
    {
        "anchor": "Nuclear spin physics in quantum dots: an optical investigation: The mesoscopic spin system formed by the 10E4-10E6 nuclear spins in a\nsemiconductor quantum dot offers a unique setting for the study of many-body\nspin physics in the condensed matter. The dynamics of this system and its\ncoupling to electron spins is fundamentally different from its bulk\ncounter-part as well as that of atoms due to increased fluctuations that result\nfrom reduced dimensions. In recent years, the interest in studying quantum dot\nnuclear spin systems and their coupling to confined electron spins has been\nfueled by its direct implication for possible applications of such systems in\nquantum information processing as well as by the fascinating nonlinear\n(quantum-)dynamics of the coupled electron-nuclear spin system. In this\narticle, we review experimental work performed over the last decades in\nstudying this mesoscopic,coupled electron-nuclear spin system and discuss how\noptical addressing of electron spins can be exploited to manipulate and\nread-out quantum dot nuclei. We discuss how such techniques have been applied\nin quantum dots to efficiently establish a non-zero mean nuclear spin\npolarization and, most recently, were used to reduce fluctuations of the\naverage quantum dot nuclear spin orientation. Both results in turn have\nimportant implications for the preservation of electron spin coherence in\nquantum dots, which we discuss. We conclude by speculating how this recently\ngained understanding of the quantum dot nuclear spin system could in the future\nenable experimental observation of quantum-mechanical signatures or possible\ncollective behavior of mesoscopic nuclear spin ensembles.",
        "positive": "Deconstructing the governing dissipative phenomena in the nanoscale: An expression describing the controlling parameters involved in short range\nnanoscale dissipation is proposed and supported by simulations and experimental\nfindings. The expression is deconstructed into the geometrical, dynamic,\nchemical and mechanical properties of the system. In atomic force microscopy\nthese are translated into 1) tip radius and tip-sample deformation, 2) resonant\nfrequency and oscillation amplitude and 3) hysteretic and viscous dissipation.\nThe latter are characteristic parameters defining the chemical and mechanical\nproperties of the tip-sample system. Long range processes are also discussed\nand footprints are identified in experiments conducted on mica and silicon\nsamples. The present methodology can be exploited to validate or invalidate\nnanoscale dissipative models by comparing predictions with experimental\nobservables."
    },
    {
        "anchor": "Temperature-induced increase of spin spiral periods: Spin-polarized scanning tunneling microscopy investigations reveal a\nsignificant increase of the magnetic period of spin spirals in\nthree-atomic-layer-thick Fe films on Ir(111), from about 4nm at 8K to about\n65nm at room temperature. We attribute this considerable influence of\ntemperature on the magnetic length scale of noncollinear spin states to\ndifferent exchange interaction coefficients in the different Fe layers. We thus\npropose a classical spin model which reproduces the experimental observations\nand in which the crucial feature is the presence of magnetically coupled atomic\nlayers with different interaction strengths. This model might also apply for\nmany other systems, especially magnetic multilayers.",
        "positive": "Magnetic flux in mesoscopic rings: capacitance, inertia and kinetics: We consider mesoscopic non-superconducting rings with an effective\ncapacitance. We propose a Hamiltonian model describing magnetic flux in such\nrings. Next we incorporate dissipation and thermal fluctuations into our\nkinetic model. We consider kinetics in limiting regimes of strong and weak\ncoupling to thermal bath."
    },
    {
        "anchor": "Master equation approach to magnon relaxation and dephasing: There has been a recent upsurge of interest in the quantum properties of\nmagnons for quantum information processing. An important issue is to examine\nthe stability of quantum states of magnons against various relaxation and\ndephasing channels. Since the interaction of magnons in magnetic systems may\nfall in the ultra-strong and even deep-strong coupling regimes, the relaxation\nprocess of magnon states is quite different from the more common quantum\noptical systems. Here we study the relaxation and dephasing of magnons based on\nthe Lindblad formalism and derive a generalized master equation that describes\nthe quantum dynamics of magnons. Employing this master equation, we identify\ntwo distinct dissipation channels for squeezed magnons, i.e., the local\ndissipation and collective dissipation, which play a role for both ferromagnets\nand antiferromagnets. The local dissipation is caused by the independent\nexchange of angular momentum between the magnonic system and the environment,\nwhile the collective dissipation is dressed by the parametric interactions of\nmagnons and it enhances the quantumness and thermal stability of squeezed\nmagnons. Further, we show how this formalism can be applied to study the pure\ndephasing of magnons caused by four-magnon scattering and magnon-phonon\ninteractions. Our results provide the theoretical tools to study the\ndecoherence of magnons within a full quantum-mechanical framework and further\nbenefit the use of quantum states of magnons for information processing.",
        "positive": "Hamiltonian Description of Composite Fermions: Aftermath: The Lowest Landau Level (LLL), long distance theory of Composite Fermions\n(CF) developed by Murthy and myself is minimally extended to all distances,\nguided by very general principles. The resulting theory is mathematically\nconsistent, and physically appealing: we clearly see the electron and the\nvortices binding to form the CF. The meaning of the constraints, their role in\nensuring compressibility of dipolar objects at $\\nu =1/2$, and the\nobservability of dipoles are clarified."
    },
    {
        "anchor": "Understanding of phase noise squeezing under fractional synchronization\n  of non-linear spin transfer vortex oscillator: We investigate experimentally the synchronization of a vortex based spin\ntransfer oscillator to an external rf current whose frequency is at multiple\nintegers, as well as half integer, of the oscillator frequency. Through a\ntheoretical study of the locking process, we highlight both the crucial role of\nthe symmetries of the spin torques acting on the magnetic vortex and the\nnonlinear properties of the oscillator on the phase locking process. Through\nthe achievement of a perfect injection locking state, we report a record phase\nnoise reduction down to -90dBc/Hz at 1 kHz offset frequency. The phase noise of\nthese nanoscale oscillators is demonstrating as being low and controllable\nwhich is of significant importance for real applications using spin transfer\ndevices.",
        "positive": "Sensitivity Analysis of a Graphene Field-Effect Transistors by means of\n  Design of Experiments: Graphene, due to its unique electronic structure favoring high carrier\nmobility, is considered a promising material for use in high-speed electronic\ndevices in the post-silicon electronic era. For this reason, experimental\nresearch on graphene-based field-effect transistors (GFETs) has rapidly\nincreased in the last years. However, despite the continuous progress in the\noptimization of such devices many critical issues remain to be solved such as\ntheir reproducibility and performance uniformity against possible variations\noriginated by the manufacturing processes or the operating conditions. In the\npresent work, changes of the ID-VDS characteristics of a Graphene Field-Effect\nTransistors, caused by a tolerance of 10% in the active channel (i.e. its\nlength and width) and in the top oxide thickness are numerically investigated\nin order to assess the reliability of such devices. Design of Experiments (DoE)\nis adopted with the aim to identify the most influential factors on the\nelectrical performance of the device, so that the fabrication process may be\nsuitably optimized."
    },
    {
        "anchor": "Mass measurement of graphene using quartz crystal microbalances: Current wafer-scale fabrication methods for graphene-based electronics and\nsensors involve the transfer of single-layer graphene by a support polymer.\nThis often leaves some polymer residue on the graphene, which can strongly\nimpact its electronic, thermal, and mechanical resonance properties. To assess\nthe cleanliness of graphene fabrication methods, it is thus of considerable\ninterest to quantify the amount of contamination on top of the graphene. Here,\nwe present a methodology for direct measurement of the mass of the graphene\nsheet using quartz crystal microbalances (QCM). By monitoring the QCM resonance\nfrequency during removal of graphene in an oxygen plasma, the total mass of the\ngraphene and contamination is determined with sub-graphene-monolayer accuracy.\nSince the etch-rate of the contamination is higher than that of graphene,\nquantitative measurements of the mass of contaminants below, on top, and\nbetween graphene layers are obtained. We find that polymer-based dry transfer\nmethods can increase the mass of a graphene sheet by a factor of 10. The\npresented mass measurement method is conceptually straightforward to interpret\nand can be used for standardized testing of graphene transfer procedures in\norder to improve the quality of graphene devices in future applications.",
        "positive": "Two-dimensional orbital Hall insulators: The orbital-Hall effect (OHE), similarly to the spin-Hall effect (SHE),\nrefers to the creation of a transverse flow of orbital angular momentum that is\ninduced by a longitudinally applied electric field. For systems in which the\nspin-orbit coupling (SOC) is sizeable, the orbital and spin angular momentum\ndegrees of freedom are coupled, and an interrelationship between charge, spin\nand orbital angular momentum excitations is naturally established. The OHE has\nbeen explored mostly in metallic systems, where it can be quite strong.\nHowever, several of its features remain unexplored in two-dimensional (2D)\nmaterials. Here, we investigate the role of orbital textures for the OHE\ndisplayed by multi-orbital 2D materials. We predict the appearance of a rather\nlarge orbital Hall effect in these systems both in their metallic and\ninsulating phases. In some cases, the orbital Hall currents are larger than the\nspin Hall ones, and their use as information carriers widens the development\npossibilities of novel spin-orbitronic devices."
    },
    {
        "anchor": "Pattern generation and symbolic dynamics in a nanocontact vortex\n  oscillator: Harnessing chaos or intrinsic nonlinear behaviours from dynamical systems is\na promising avenue for the development of unconventional information processing\ntechnologies. However, the exploitation of such features in spintronic devices\nhas not been attempted despite the many theoretical and experimental evidence\nof nonlinear behaviour of the magnetization dynamics in nanomagnetic systems.\nHere, we propose a first step in that direction by unveiling and characterizing\nthe patterns and symbolic dynamics originating from the nonlinear chaotic\ntime-resolved electrical signals generated experimentally by a nanocontact\nvortex oscillator (NCVO). We use advanced filtering methods to dissociate\nnonlinear deterministic patterns from thermal fluctuations and show that the\nemergence of chaos results in the unpredictable alternation of simple\noscillatory patterns controlled by the NCVO's core-polarity switching. With\nphase-space reconstruction techniques, we perform a symbolic analysis of the\ntime series to assess the level of complexity and entropy generated in the\nchaotic regime. We find that at the centre of its incommensurate region, it can\nexhibit maximal entropy and complexity. This suggests that NCVOs are promising\nnonlinear nanoscale source of entropy that could be harnessed for information\nprocessing.",
        "positive": "Time-dependent magnetotransport of a wave packet in a quantum wire with\n  embedded quantum dots: We consider wave packet propagation in a quantum wire with either an embedded\nantidot or an embedded parallel double open quantum dot under the influence of\na uniform magnetic field. The magnetoconductance and the time evolution of an\nelectron wave packet are calculated based on the Lippmann-Schwinger formalism.\nThis approach allows us to look at arbitrary embedded potential profiles and\nillustrate the results by performing computational simulations for the\nconductance and the time evolution of the electron wave packet through the\nquantum wire. In the double-dot system we observe a long-lived resonance state\nthat enhances the spatial spreading of the wave packet, and quantum\nskipping-like trajectories are induced when the envelop function of the wave\npacket covers several subbands in appropriate magnetic fields."
    },
    {
        "anchor": "Effect of quantum Hall edge strips on valley splitting in silicon\n  quantum wells: We determine the energy splitting of the conduction-band valleys in\ntwo-dimensional electrons confined to low-disorder Si quantum wells. We probe\nthe valley splitting dependence on both perpendicular magnetic field $B$ and\nHall density by performing activation energy measurements in the quantum Hall\nregime over a large range of filling factors. The mobility gap of the\nvalley-split levels increases linearly with $B$ and is strikingly independent\nof Hall density. The data are consistent with a transport model in which valley\nsplitting depends on the incremental changes in density $eB/h$ across quantum\nHall edge strips, rather than the bulk density. Based on these results, we\nestimate that the valley splitting increases with density at a rate of 116\n$\\mu$eV/10$^{11}$cm$^{-2}$, consistent with theoretical predictions for\nnear-perfect quantum well top interfaces.",
        "positive": "Fast heat flux modulation at the nanoscale: We introduce a new concept for electrically controlled heat flux modulation.\nA flux contrast larger than 10 dB is expected with switching time on the order\nof tens of nanoseconds. Heat flux modulation is based on the interplay between\nradiative heat transfer at the nanoscale and phase change materials. Such large\ncontrasts are not obtainable in solids, or in far field. As such this opens up\nnew horizons for temperature modulation and actuation at the nanoscale."
    },
    {
        "anchor": "Transient effects in quantum dots contacted via topological\n  superconductor: We investigate gradual development of the quasiparticle states in two quantum\ndots attached to opposite sides of the topological superconducting nanowire,\nhosting the boundary modes. Specifically, we explore the non-equilibrium\ncross-correlations transmitted between these quantum dots via the zero-energy\nMajorana modes. From the analytical and numerical results we reveal nonlocal\nfeatures in the transient behavior of electron pairing, which subsequently\ncease while the hybrid structure evolves towards its asymptotic steady limit\nconfiguration. We estimate duration of these temporary nonlocal phenomena and\ninspect their possible manifestation in the quench-driven processes. Such\ndynamical effects might play an important role in braiding protocols of the\ntopological and/or conventional superconducting quantum bits using nanoscopic\nhybrid structures.",
        "positive": "Reply to Comment on ``Quantum Pump for Spin and Charge Transport in a\n  Luttinger Liquid'': We show that Feldman and Gefen's comment revolves around a trivial issue -\nthe relative magnitudes for the two crossover scales in the problem."
    },
    {
        "anchor": "Spin-orbit interaction controlled properties of two-dimensional\n  superlattices: Spintronic crystals: The band structure of two-dimensional artificial superlattices in the\npresence of (Rashba-type) spin-orbit interaction (SOI) is presented. The\nposition and shape of the energy bands in these spintronic crystals depend on\nthe geometry as well as the strength of the SOI, which can be tuned by external\ngate voltages. For finite mesoscopic arrays we show that their conductance\nproperties can be understood from these spin-dependent band diagrams.",
        "positive": "Electronic transport properties of topological insulator films and low\n  dimensional superconductors: In this review, we present a summary of some recent experiments on\ntopological insulators (TIs) and superconducting nanowires and films.\nElectron-electron interaction (EEI), weak anti-localization (WAL) and\nanisotropic magneto-resistance (AMR) effect found in TI films by transport\nmeasurements are reported. Then, transport properties of superconducting films,\nbridges and nanowires and proximity effect in non-superconducting nanowires are\ndescribed. Finally, the interplay between TIs and superconductors (SCs) is also\ndiscussed."
    },
    {
        "anchor": "A mechanism for electrostatically generated magnetoresistance in chiral\n  systems without spin-dependent transport: Significant attention has been drawn to electronic transport in chiral\nmaterials coupled to ferromagnets in the chirality induced spin selectivity\n(CISS) effect. A large magnetoresistance (MR) is usually observed which is\nwidely interpreted to originate from spin (dependent) transport. However, there\nare severe discrepancies between the experimental results and theoretical\ninterpretations, most notably the apparent failure of the Onsager reciprocity\nrelation in the linear response regime. We provide an alternative explanation\nfor the mechanism of the two terminal MR in chiral systems coupled to a\nferromagnet. For this we point out that it was observed that the electrostatic\ncontact potential of chiral materials on a ferromagnet depends on the\nmagnetization direction and chirality. In our explanation this causes the\ntransport barrier to be modified by the magnetization direction, already in\nequilibrium, in the absence of a bias current. This strongly alters the charge\ntransport through/over the barrier, not requiring spin transport. This provides\na mechanism that allows the linear response resistance to be sensitive to the\nmagnetization direction and also explains the failure of the Onsager\nreciprocity relations. We propose experimental configurations to confirm our\nalternative mechanism for MR.",
        "positive": "Modeling surface roughness scattering in metallic nanowires: Ando's model provides a rigorous quantum-mechanical framework for\nelectron-surface roughness scattering, based on the detailed roughness\nstructure. We apply this method to metallic nanowires and improve the model\nintroducing surface roughness distribution functions on a finite domain with\nanalytical expressions for the average surface roughness matrix elements. This\napproach is valid for any roughness size and extends beyond the commonly used\nPrange-Nee approximation. The resistivity scaling is obtained from the\nself-consistent relaxation time solution of the Boltzmann transport equation\nand is compared to Prange-Nee's approach and other known methods. The results\nshow that a substantial drop in resistivity can be obtained for certain\ndiameters by achieving a large momentum gap between Fermi level states with\npositive and negative momentum in the transport direction."
    },
    {
        "anchor": "Screening, Friedel oscillations and low-temperature conductivity in\n  topological insulator thin films: In thin topological insulator films, the top and bottom surfaces are coupled\nby tunneling, which restores backscattering and strongly affects screening. We\ncalculate the dielectric function in the random phase approximation obtaining a\nclosed-form result. Unlike independent TI surfaces, the dielectric function of\nthin films exhibits a valley as a function of wavenumber $q$ and tunneling, as\nwell as a cusp at $q=2k_F$, with $k_F$ the Fermi wave vector. As a result of\nthe cusp, Friedel oscillations decay with distance $r$ as\n$\\sin(2k_Fr)/(2k_Fr)^2$. We determine the longitudinal conductivity $\\sigma$ in\nthe first Born approximation at low temperatures where screened impurities\nprovide the dominant scattering mechanism. At high electron densities $n_e$,\n$\\sigma \\propto n_e$, while at low densities $\\sigma \\propto n_e^{3/2}$.",
        "positive": "Electronic inhomogeneities in graphene: the role of the substrate\n  interaction and chemical doping: We probe the local inhomogeneities of the electronic properties of graphene\nat the nanoscale using scanning probe microscopy techniques. First, we focus on\nthe study of the electronic inhomogeneities caused by the graphene-substrate\ninteraction in graphene samples exfoliated on silicon oxide. We find that\ncharged impurities, present in the graphene-substrate interface, perturb the\ncarrier density significantly and alter the electronic properties of graphene.\nThis finding helps to understand the observed device-to-device variation\ntypically observed in graphene-based electronic devices. Second, we probe the\neffect of chemical modification in the electronic properties of graphene, grown\nby chemical vapour deposition on nickel. We find that both the chemisorption of\nhydrogen and the physisorption of porphyrin molecules strongly depress the\nconductance at low bias indicating the opening of a bandgap in graphene, paving\nthe way towards the chemical engineering of the electronic properties of\ngraphene."
    },
    {
        "anchor": "Electron-hole asymmetry in two-terminal graphene devices: A theoretical model is proposed to describe asymmetric gate-voltage\ndependence of conductance and noise in two-terminal ballistic graphene devices.\nThe model is analyzed independently within the self-consistent Hartree and\nThomas-Fermi approximations. Our results justify the prominent role of metal\ncontacts in recent experiments with suspended graphene flakes. The\ncontact-induced electrostatic potentials in graphene demonstrate a power-law\ndecay with the exponent varying from -1 to -0.5. Within our model we explain\nelectron-hole asymmetry and strong Fabri-Perot oscillations of the conductance\nand noise at positive doping, which were observed in many experiments with\nsubmicrometer samples. Limitations of the Thomas-Fermi approximation in a\nvicinity of the Dirac point are discussed.",
        "positive": "Dynamics of localized modes in a composite multiferroic chain: In a coupled ferroelectric/ferromagnetic system, i.e. a composite\nmultiferroic, the propagation of magnetic or ferroelectric excitations across\nthe whole structure is a key issue for applications. Of a special interest is\nthe dynamics of localized magnetic or ferroelectric modes (LM) across the\nferroelectric-ferromagnetic interface, particularly when the LM's carrier\nfrequency is in the band of the ferroelectric and in the band gap of the\nferromagnet. For a proper choice of the system's parameters, we find that there\nis a threshold amplitude above which the interface becomes transparent and a\nband gap ferroelectric LM penetrates the ferromagnetic array. Below that\nthreshold, the LM is fully reflected. Slightly below this transmission\nthreshold, the addition of noise may lead to energy transmission, provided that\nthe noise level is not too low nor too high, an effect that resembles\nstochastic resonance. These findings represent an important step towards the\napplication of ferroelectric and/or ferromagnetic LM-based logic."
    },
    {
        "anchor": "Shot-noise of quantum chaotic systems in the classical limit: Semiclassical methods can now explain many mesoscopic effects (shot-noise,\nconductance fluctuations, etc) in clean chaotic systems, such as chaotic\nquantum dots. In the deep classical limit (wavelength much less than system\nsize) the Ehrenfest time (the time for a wavepacket to spread to a classical\nsize) plays a crucial role, and random matrix theory (RMT) ceases to apply to\nthe transport properties of open chaotic systems.\n  Here we summarize some of our recent results for shot-noise (intrinsically\nquantum noise in the current through the system) in this deep classical limit.\nFor systems with perfect coupling to the leads, we use a phase-space basis on\nthe leads to show that the transmission eigenvalues are all 0 or 1 -- so\ntransmission is noiseless [Whitney-Jacquod, Phys. Rev. Lett. 94, 116801 (2005),\nJacquod-Whitney, Phys. Rev. B 73, 195115 (2006)]. For systems with\ntunnel-barriers on the leads we use trajectory-based semiclassics to extract\nuniversal (but non-RMT) shot-noise results for the classical regime [Whitney,\nPhys. Rev. B 75, 235404 (2007)].",
        "positive": "Zero-bias molecular electronics: Exchange-correlation corrections to\n  Landauer's formula: Standard first principles calculations of transport through single molecules\nmiss exchange-correlation corrections to the Landauer formula. From Kubo\nresponse theory, both the Landauer formula and these corrections in the limit\nof zero bias are derived and calculations are presented."
    },
    {
        "anchor": "Investigating optically-excited THz standing spin waves using\n  noncollinear magnetic bilayers: We investigate optically excited THz standing spin waves in noncollinear\nmagnetic bilayers. Using femtosecond laser-pulse excitation, a spin current is\ngenerated in the first ferromagnetic (FM) layer, and flows through a conductive\nspacer layer to be injected into the second (transverse) FM layer, where it\nexerts a spin-transfer torque on the magnetization and excites higher-order\nstanding spin waves. We show that the noncollinear magnetic bilayer is a\nconvenient tool that allows easy excitation of THz spin waves, and can be used\nto investigate the dispersion and thereby the spin wave stiffness parameter in\nthe thin-film regime. This is experimentally demonstrated using wedge-shaped Co\nand CoB (absorption) layers. Furthermore, the damping of these THz spin waves\nis investigated, showing a strong increase of the damping with decreasing\nabsorption layer thickness, much stronger than expected from interface spin\npumping effects. Additionally, a previously unseen sudden decrease in the\ndamping for the thinnest films is observed. A model for the additional damping\ncontribution incorporating both these observations is proposed.",
        "positive": "Effects of low-dimensional material channels on energy consumption of\n  Nano-devices: It is commonly believed that the significant energy saving advantages are\nbelonged to the logic circuits which operate at low temperature as less enegy\nis needed for cooling them to the treshold temperature after operation. Also,\nnanoscale thermal management, efficient energy usage in nanoscale and\nespecially thermal optimization are the most challenging issues, while dealing\nwith the new generation of transistors as the miniaturizing unlimitedly the\nsilicon channels of the transistors has resulted in an increase in the energy\nconsumption of computers and the leakage currents. In this paper, the\nnon-Fourier thermal attitudes of well-known two-dimensional crystalline\nmaterials of graphene, blue phosphorene, germanene, silicene and MoS$_2$ as the\nsilicon channels replacements are studied by using the phonon Monte-Carlo\nmethod. We show that graphene and blue phosphorene have the least maximum\ntemperature, representer of the reliability of the transistors, among the all\nfive investigated nano-channels during the Monte-Cralo simulation. The\nestablished hotspots of these two materials are always cooler, not reaching the\ntemperature threshold level, and they lose the heat much faster as the heat\ngeneration zone is switched off. The obtained results considered along with the\nelectrical disadvantages of the graphene layer, suggests the blue phosphorene\nas the more thermally appropriate and optimal choice for the silicon channel\nreplacement in new designed field effect transistors. That is to say that the\nlimit of the energy and economic cost of the producing the advanced blue\nphosphorene chips meets the value of the product for the computing enterprise."
    },
    {
        "anchor": "Scattering of exchange spin waves from regions of modulated\n  magnetization: We investigate the reflection coefficient of spin waves propagating in an\nultra-thin ferromagnetic film with regions where saturation magnetization is\nmodulated. We find analytically and using micromagnetic simulations that there\nare transmission resonances that depend on the width of the regions and on the\nenergy of excitation. Our results resemble the quantum mechanical\nRamsauer-Townsend effect in which an electron with certain energies can\npropagate above a potential field without scattering. Our findings are useful\nfor reconfigurable magnonic devices where the saturation magnetization can be\ndynamically controlled via a thermal landscape.",
        "positive": "Pseudogauge field driven acoustoelectric current in two-dimensional\n  hexagonal Dirac materials: Using a diagrammatic scheme, we study the acoustoelectric effects in\ntwo-dimensional (2D) hexagonal Dirac materials due to the sound-induced\npseudo-gauge field. We analyze both uniform and {\\em spatially dispersive}\ncurrents in response to copropagating and counterpropagating sound waves,\nrespectively. In addition to the longitudinal acoustoelectric current, we\nobtain an exotic {\\em transverse} charge current flowing perpendicular to the\nsound propagation direction owing to the interplay of transverse and\nlongitudinal gauge field components $j_T\\propto A_L A^\\ast_T$. In contrast to\nthe almost isotropic directional profile of the longitudinal uniform current, a\nhighly anisotropic transverse component $j_T\\sim\\sin(6\\theta)$ is achieved that\nstems from the inherited three-fold symmetry of the hexagonal lattice. However,\nboth longitudinal and transverse parts of the dispersive current are predicted\nto be strongly anisotropic $\\sim\\sin^2(3\\theta)$ or $\\cos^2(3\\theta)$. We\nquantitatively estimate the pseudogauge field contribution to the\nacoustoelectric current that can be probed in future experiments in graphene\nand other 2D hexagonal Dirac materials."
    },
    {
        "anchor": "Atomic spin chain realization of a model for quantum criticality: The ability to manipulate single atoms has opened up the door to constructing\ninteresting and useful quantum structures from the ground up. On the one hand,\nnanoscale arrangements of magnetic atoms are at the heart of future quantum\ncomputing and spintronic devices; on the other hand, they can be used as\nfundamental building blocks for the realization of textbook many-body quantum\nmodels, illustrating key concepts such as quantum phase transitions,\ntopological order or frustration. Step-by-step assembly promises an interesting\nhandle on the emergence of quantum collective behavior as one goes from one, to\nfew, to many constituents. To achieve this, one must however maintain the\nability to tune and measure local properties as the system size increases.\nHere, we use low-temperature scanning tunneling microscopy to construct arrays\nof magnetic atoms on a surface, designed to behave like spin-1/2 XXZ Heisenberg\nchains in a transverse field, for which a quantum phase transition from an\nantiferromagnetic to a paramagnetic phase is predicted in the thermodynamic\nlimit. Site-resolved measurements on these finite size realizations reveal a\nnumber of sudden ground state changes when the field approaches the critical\nvalue, each corresponding to a new domain wall entering the chains. We observe\nthat these state crossings become closer for longer chains, indicating the\nonset of critical behavior. Our results present opportunities for further\nstudies on quantum behavior of many-body systems, as a function of their size\nand structural complexity.",
        "positive": "Magnetic chirality controlled by the interlayer exchange interaction: Chiral magnetism, wherein there is a preferred sense of rotation of the\nmagnetization, has become a key aspect for future spintronic applications. It\ndetermines the chiral nature of magnetic textures, such as skyrmions, domain\nwalls or spin spirals, and a specific magnetic chirality is often required for\nspintronic applications. Current research focuses on identifying and\ncontrolling the interactions that define the magnetic chirality. The influence\nof the interfacial Dzyaloshinskii-Moriya interaction (iDMI) and, recently, the\ndipolar interactions have previously been reported. Here, we experimentally\ndemonstrate that an indirect interlayer exchange interaction can be used as an\nadditional tool to effectively manipulate the magnetic chirality. We image the\nchirality of magnetic domain walls in a coupled bilayer system using scanning\nelectron microscopy with polarization analysis (SEMPA). Upon increasing the\ninterlayer exchange coupling, we induce a transition of the magnetic chirality\nfrom clockwise rotating N\\'eel walls to degenerate Bloch-N\\'eel domain walls\nand we confirm our findings with micromagnetic simulations. In multi-layered\nsystems relevant for skyrmion research a uniform magnetic chirality across the\nmagnetic layers is often desired. Additional simulations show that this can be\nachieved for reduced iDMI values when exploiting the interlayer exchange\ninteraction. This work opens up new ways to control and tailor the magnetic\nchirality by the interlayer exchange interaction."
    },
    {
        "anchor": "Conductance asymmetry of graphene pn junction: We use the non-equilibrium Green function (NEGF) method in the ballistic\nlimit to provide a quantitative description of the conductance of graphene pn\njunctions - an important building block for graphene electronics devices. In\nthis paper, recent experiments on graphene junctions are explained by a\nballistic transport model, but only if the finite junction transition width,\nDw, is accounted for. In particular, the experimentally observed anamolous\nincrease in the resistance asymmetry between nn and np junctions under low\nsource/drain charge density conditions is also quantitatively captured by our\nmodel. In light of the requirement for sharp junctions in applications such as\nelectron focusing, we also examine the pn junction conductance in the regime\nwhere Dw is small and find that wavefunction mismatch (so-called pseudo-spin)\nplays a major role in sharp pn junctions.",
        "positive": "Spin-Orbit Interaction Enabled High-Fidelity Two-Qubit Gates: We study the implications of spin-orbit interaction (SOI) for two-qubit gates\n(TQGs) in semiconductor spin qubit platforms. SOI renders the exchange\ninteraction governing qubit pairs anisotropic, posing a serious challenge for\nconventional TQGs derived for the isotropic Heisenberg exchange. Starting from\nmicroscopic level, we develop a concise computational Hamiltonian that captures\nthe essence of SOI, and use it to derive properties of the rotating-frame time\nevolutions. Two key findings are made. First, for the\ncontrolled-phase/controlled-Z gate, we show and analytically prove the\nexistence of ``SOI nodes'' where the fidelity can be optimally enhanced, with\nonly slight modifications in terms of gate time and local phase corrections.\nSecond, we discover and discuss novel two-qubit dynamics that are inaccessible\nwithout SOI -- the reflection gate and the direct controlled-not gate. The\nrelevant conditions and achievable fidelities are studied for the direct\ncontrolled-not gate."
    },
    {
        "anchor": "Difference in charge and spin dynamics in a quantum dot-lead coupled\n  system: We analyze time evolution of charge and spin states in a quantum dot coupled\nto an electric reservoir. Utilizing high-speed single-electron detection, we\nfocus on dynamics induced by the first-order tunneling. We find that there is a\ndifference between the spin and the charge relaxation: the former appears\nslower than the latter. The difference depends on the Fermi occupation factor\nand the spin relaxation becomes slower when the energy level of the quantum dot\nis lowered. We explain this behavior by a theory which includes the first-order\ntunneling processes. We conduct detailed comparison of the experiment and the\ntheory with changing the energy of the quantum dot levels, and the theory can\nreproduce the experimental results.",
        "positive": "Tunable magnetization relaxation in spin valves: In spin values the damping parameters of the free layer are determined\nnon-locally by the entire magnetic configuration. In a dual spin valve\nstructure that comprises a free layer embedded between two pinned layers, the\nspin pumping mechanism, in combination with the angular momentum conservation,\nrenders the tensor-like damping parameters tunable by varying the interfacial\nand diffusive properties. Simulations based on the Landau-Lifshitz-Gilbert\nphenomenology for a macrospin model are performed with the tensor-like damping\nand the relaxation time of the free layer magnetization is found to be largely\ndependent on while tunable through the magnetic configuration of the\nsource-drain magnetization."
    },
    {
        "anchor": "Inelastic Scattering in Metal-H2-Metal Junctions: We present first-principles calculations of the dI/dV characteristics of an\nH2 molecule sandwiched between Au and Pt electrodes in the presence of\nelectron-phonon interactions. The conductance is found to decrease by a few\npercentage at threshold voltages corresponding to the excitation energy of\nlongitudinal vibrations of the H2 molecule. In the case of Pt electrodes, the\ntransverse vibrations can mediate transport through otherwise non-transmitting\nPt $d$-channels leading to an increase in the differential conductance even\nthough the hydrogen junction is characterized predominately by a single almost\nfully open transport channel. In the case of Au, the transverse modes do not\naffect the dI/dV because the Au d-states are too far below the Fermi level. A\nsimple explanation of the first-principles results is given using scattering\ntheory. Finally, we compare and discuss our results in relation to experimental\ndata.",
        "positive": "Image-charge induced localization of molecular orbitals at\n  metal-molecule interfaces: Self-consistent GW calculations: Quasiparticle (QP) wave functions, also known as Dyson orbitals, extend the\nconcept of single-particle states to interacting electron systems. Here we\nemploy many-body perturbation theory in the GW approximation to calculate the\nQP wave functions for a semi-empirical model describing a $\\pi$-conjugated\nmolecular wire in contact with a metal surface. We find that image charge\neffects pull the frontier molecular orbitals toward the metal surface while\norbitals with higher or lower energy are pushed away. This affects both the\nsize of the energetic image charge shifts and the coupling of the individual\norbitals to the metal substrate. Full diagonalization of the QP equation and,\nto some extent, self-consistency in the GW self-energy, is important to\ndescribe the effect which is not captured by standard density functional theory\nor Hartree-Fock. These results should be important for the understanding and\ntheoretical modeling of electron transport across metal-molecule interfaces."
    },
    {
        "anchor": "MIRO-like oscillations of magneto-resistivity in GaAs heterostructures\n  induced by THz radiation: We report on the study of terahertz radiation induced MIRO-like oscillations\nof magneto-resistivity in GaAs heterostructures. Our experiments provide an\nanswer on two most intriguing questions - effect of radiation helicity and the\nrole of the edges - yielding crucial information for understanding of the MIRO\norigin. Moreover, we demonstrate that the range of materials exhibiting\nradiation-induced magneto-oscillations can be largely extended by using\nhigh-frequency radiation.",
        "positive": "Photovoltaic properties enhanced by the tunneling effect in a coupled\n  quantum dot photocell: Double quantum dots (DQDs) have emerged as versatile and efficient absorbing\nlight devices owing to their more multiple adjusting parameters than the single\nQD's. Using the system-reservoir theory, tunneling effect on the quantum\nphotovoltaic properties is evaluated detailedly in a DQDs photocell with\ndifferent energy mismatches under different temperatures. Repopulation of\nphoto-generated carriers in two excited states is generated by electron\ntunneling effect between two coupled QD pairs, which brings out more efficient\nquantum photovoltaic yields evaluated by the short-circuit current,\nopen-circuit voltage and output power through the current-voltage and\npower-voltage characteristics. Further discussion reveals that the quantum\nphotovoltaic properties are enhanced by the ambient environment temperatures\nbut weakened by the energy mismatches. However, the weakening effect caused by\nthe energy mismatches can be greatly reduced by tunneling effect. Insights into\ntunneling effect between two adjacent QD not only facilitate a better\nunderstanding of the fundamentals in carriers transport, but also provide novel\nstrategies for efficient artificial assembled QD arrays photocell inspired by\nthis proposed DQDs photocell model."
    },
    {
        "anchor": "Novel Collective Excitation in Spin Textured Edges of Quantum Hall\n  Systems: We study the electric and magnetic properties of the edge of a\ntwo-dimensional electron gas in presence of a magnetic field and at filling\nfactor unity. The existence of a spin textured edge is proved as a function of\nthe Zeeman coupling and of the smoothness of the confining potential. We also\ncalculate the low energy excitation of the spin textured phase. We obtain that\nin addition to the classical edge magnetoplasmons at small wavectors, there is\nan almost dispersionless excitation, with a finite gap of energy at zero\nwavevector. This excitation is associated with the broken symmetry of the spin\ntextured edge phase.",
        "positive": "Dependence of resistivity on surface profile in nanoscale metal films\n  and wires: We extend quantum models of nanowire surface scattering to incorporate bulk\nresistivity and extract an expression for the increased resistivity due to\nsurface roughness. To learn how to improve conductivity, we calculate\nconductivity degradation from individual wavelengths of surface roughness, and\nshow how these can be convolved to give resistivity for arbitrary surfaces. We\nreview measurements from Cu films and conclude that roughness at short\nwavelengths (less than 100 nm) dominates scattering, and that primarily\nspecular scattering should be achievable for RMS roughness below about 0.7 nm."
    },
    {
        "anchor": "Chirality tunneling in mesoscopic antiferromagnetic domain walls: We consider a domain wall in the mesoscopic quasi-one-dimensional sample\n(wire or stripe) of weakly anisotropic two-sublattice antiferromagnet, and\nestimate the probability of tunneling between two domain wall states with\ndifferent chirality. Topological effects forbid tunneling for the systems with\nhalf-integer spin S of magnetic atoms which consist of odd number of chains N.\nExternal magnetic field yields an additional contribution to the Berry phase,\nresulting in the appearance of two different tunnel splittings in any\nexperimental setup involving a mixture of odd and even N, and in oscillating\nfield dependence of the tunneling rate with the period proportional to 1/N.",
        "positive": "The Modulation of de Haas-van Alphen Effect in Graphene by Electric\n  Field: This paper is to explore the de Haas-van Alphen effect $(dHvA)$ of graphene\nin the presence of an in-plane uniform electric field. Three major findings are\nyielded. First of all, the electric field is found to modulate the de Haas-van\nAlphen magnetization and magnetic susceptibility through the dimensionless\nparameter $(\\beta =\\frac{E}{\\upsilon_{F}B})$. As the parameter $\\beta$\nincreases, the values of magnetization and magnetic susceptibility increase to\npositive infinity or decrease to negative infinity at the exotic point\n$\\beta_{c}=1$. Besides, the $dHvA$ oscillation amplitude rises abruptly to\ninfinity for zero temperature at $\\beta_{c}=1$, but eventually collapses at a\nfinite temperature thereby leading to the vanishing of de Haas-van Alphen\neffect. In addition, the magnetic susceptibility depends on the electric and\nmagnetic fields, suggesting that the graphene should be a non-linear magnetic\nmedium in the presence of the external field. These results, which are\ndifferent from those obtained in the standard nonrelativistic 2D electron gas,\nare attributed to its anomalous Landau level spectrum in graphene."
    },
    {
        "anchor": "Multiscale Phonon Conduction in Nanostructured Materials Predicted by\n  Bulk Thermal Conductivity Accumulation Function: We develop a computational framework, based on the Boltzmann transport\nequation, with the ability to compute the thermal transport in nanostructured\nmaterials of any geometry using as the only input the bulk thermal conductivity\naccumulation function. The main advantage of our method is twofold. First,\nwhile the scattering times and dispersion curves are unknown for most\nmaterials, the phonon mean free path distribution can be directly obtained by\nexperiments. As a consequence, a wider range of materials can be simulated than\nwith a frequency-dependent approach. Second, when phonon dispersions are\navailable from first principles calculations, our approach allows one to\ninclude easily the whole Brillouen zone in the calculations without\ndiscretizing the phonon frequencies for all polarizations, reducing\nconsiderably the computational effort. Furthermore, after deriving the\nballistic and diffusive limits of our model, we develop a multi-scale scheme\nthat couples phonon transport across different scales, enabling efficient\nsimulations of materials with wide phonon mean free path distributions. After\nwe validate our model against the frequency-dependent approach, we apply the\nmethod to porous silicon membranes and find good agreement with experiments on\nmesoscale pores. By enabling the investigation of thermal transport in\nunexplored nanostructured materials, our method has potential to advance\nhigh-efficiency thermoelectric devices.",
        "positive": "Wave-vector dependence of spin and density multipole excitations in\n  quantum dots: We have employed time-dependent local-spin density functional theory to\nanalyze the multipole spin and charge density excitations in GaAs-AlGaAs\nquantum dots. The on-plane transferred momentum degree of freedom has been\ntaken into account, and the wave-vector dependence of the excitations is\ndiscussed. In agreement with previous experiments, we have found that the\nenergies of these modes do not depend on the transferred wave-vector, although\ntheir intensities do. Comparison with a recent resonant Raman scattering\nexperiment [C. Sch\\\"uller et al, Phys. Rev. Lett {\\bf 80}, 2673 (1998)] is\nmade. This allows to identify the angular momentum of several of the observed\nmodes as well as to reproduce their energies."
    },
    {
        "anchor": "Controllable structuring of exciton-polariton condensates in cylindrical\n  pillar microcavities: We observe condensation of exciton polaritons in quantum states composed of\nconcentric rings when exciting cylindrical pillar GaAs/AlGaAs microcavities\nnon-resonantly by a focused laser beam normally incident at the center of the\npillar. The number of rings depends on the pumping intensity and the pillar\nsize, and may achieve 5 in the pillar of 40 mkm diameter. Breaking the axial\nsymmetry when moving the excitation spot away from the pillar center leads to\ntransformation of the rings into a number of bright lobes corresponding to\nquantum states with nonzero angular momenta. The number of lobes, their shape\nand location are dependent on the spot position. We describe the\nout-of-equilibrium condensation of polaritons in the states with different\nprincipal quantum numbers and angular momenta with a formalism based on\nBoltzmann-Gross-Pitaevskii equations accounting for repulsion of polaritons\nfrom the exciton reservoir formed at the excitation spot and their spatial\nconfinement by the pillar boundary.",
        "positive": "Homotopy transitions and 3D magnetic solitons: This work provides a concept for three-dimensional magnetic solitons based on\nmapping the homotopy path between various two-dimensional solutions onto the\nthird spatial axis. The representative examples of statically stable\nconfigurations of that type in the model of an isotropic chiral magnet are\nprovided. Various static and dynamic properties of such three-dimensional\nmagnetic solitons are discussed in detail."
    },
    {
        "anchor": "Spacetime Symmetries of the Quantum Hall Effect: We study the symmetries of non-relativistic systems with an emphasis on\napplications to the fractional quantum Hall effect. A source for the energy\ncurrent of a Galilean system is introduced and the non-relativistic\ndiffeomorphism invariance studied in previous work is enhanced to a full\nspacetime symmetry, allowing us to derive a number of Ward identities. These\nsymmetries are smooth in the massless limit of the lowest Landau level. We\ndevelop a formalism for Newton-Cartan geometry with torsion to write these Ward\nidentities in a covariant form. Previous results on the connection between Hall\nviscosity and Hall conductivity are reproduced.",
        "positive": "Expansion of Graphene-Based Device Technology for Resistance Metrology: The field of Quantum Hall metrology had a strong start with the implemntation\nof GaAs-based devices, given that 2D materials systems provided access to\ninteresting quantum phenomena, including the infrastructure associated with\nmaking relevant measurements. With the technology laid out, further\nimprovements in both infrastructure and standards were achieved in the previous\ntwo decades as EG-based quantized Hall resistance (QHR) devices became\nestablished as national standards. Since the metrology community has reached\nsome understanding that a comparison against GaAs-based QHR devices had been\naccomplished, the next steps became clearer as far as how the EG-based QHR with\na single Hall bar could be further developed. Since the early 90s, it has been\nof modest interest that QHR devices have a means of interconnecting several\nsingle Hall bar elements and has since been a subject of research. NMIs are now\npresently at a juncture where consideration must be granted beyond just\nsimplicity of operation. A natural direction for resistance standards would be\nto increase the total accessible parameter space. This means using EG-based QHR\ndevices to output more than the single value at the $\\nu = 2$ plateau (about\n12.9 k$\\Omega$). A first natural question is whether one may use the $\\nu = 6$\nplateau or $\\nu = 10$ plateau, and though some work has been done with these\nLandau levels in graphene, they simply do not offer the same level of precision\nas the $\\nu = 2$ plateau."
    },
    {
        "anchor": "Intra-cell dynamics and cyclotron motion without magnetic field: Intra-cell motion endows rich non-trivial phenomena to a wide variety of\nquantum materials. The most prominent example is a transverse current in the\nabsence of a magnetic field (i.e. the anomalous Hall effect). Here we show\nthat, in addition to a dc Hall effect, anomalous Hall materials possess\ncirculating currents and cyclotron motion without magnetic field. These are\ngenerated from the intricate wavefunction dynamics within the unit cell, and\ncorrespond to interband transitions (coherences) in much the same way that\ncyclotron resonances arise from inter-Landau level transitions in\nmagneto-optics. Curiously, anomalous cyclotron motion exhibits an intrinsic\ndecay in time (even in pristine materials) displaying a characteristic power\nlaw decay. This reveals an intrinsic dephasing similar to that of inhomogeneous\nbroadening of spinors. Circulating currents can manifest as the emission of\ncircularly polarized light pulses in response to incident linearly polarized\n(pulsed) electric field, and provide a direct means of interrogating the\nintra-unit-cell dynamics of quantum materials.",
        "positive": "Comparing artificial frustrated magnets: tuning symmetry in nanomagnet\n  arrays: We study the impact of geometry on magnetostatically frustrated single-domain\nnanomagnet arrays. We examine square and hexagonal lattice arrays, as well as a\nbrickwork geometry that combines the anisotropy of the square lattice and the\ntopology of the hexagonal lattice. We find that the more highly frustrated\nhexagonal lattice allows for the most thorough minimization of the\nmagnetostatic energy, and that the pair-wise correlations between moments\ndiffer qualitatively between hexagonal and brickwork lattices, although they\nshare the same lattice topology. The results indicate that the symmetry of\nlocal interaction is more important than overall lattice topology in the\naccommodation of frustrated interactions."
    },
    {
        "anchor": "Spin-dependent transmission through a chain of rings: influence of a\n  periodically modulated spin-orbit interaction strength or ring radius: We study ballistic electron transport through a finite chain of quantum\ncircular rings in the presence of spin-orbit interaction of strength \\alpha.\nFor a single ring the transmission and reflection coefficients are obtained\nanalytically and from them the conductance for a chain of rings as a function\nof \\alpha and of the wave vector k of the incident electron. We show that due\nto destructive spin interferences the chain can be totaly opaque for certain\nranges of k the width of which depends on the value of \\alpha. A periodic\nmodulation of the strength \\alpha or of the ring radius widens up the gaps\nconsiderably and produces a nearly binary conductance output.",
        "positive": "Density of proper delay times in chaotic and integrable quantum\n  billiards: We calculate the density P(\\tau) of the eigenvalues of the Wigner-Smith time\ndelay matrix for two-dimensional rectangular and circular billiards with one\nopening. For long times, the density of these so-called \"proper delay times\"\ndecays algebraically, in contradistinction to chaotic quantum billiards for\nwhich P(\\tau) exhibits a long-time cut-off."
    },
    {
        "anchor": "Kramers pairs of Majorana corner states in a topological insulator\n  bilayer: We consider a system consisting of two tunnel-coupled two-dimensional\ntopological insulators proximitized by a top and bottom superconductor with a\nphase difference of $\\pi$ between them. We show that this system exhibits a\ntime-reversal invariant second-order topological superconducting phase\ncharacterized by the presence of a Kramers pair of Majorana corner states at\nall four corners of a rectangular sample. We furthermore investigate the effect\nof a weak time-reversal symmetry breaking perturbation and show that an\nin-plane Zeeman field leads to an even richer phase diagram exhibiting two\nnonequivalent phases with two Majorana corner states per corner as well as an\nintermediate phase with only one Majorana corner state per corner. We derive\nour results analytically from continuum models describing our system. In\naddition, we also provide independent numerical confirmation of the resulting\nphases using discretized lattice representations of the models, which allows us\nto demonstrate the robustness of the topological phases and the Majorana corner\nstates against parameter variations and potential disorder.",
        "positive": "Helical edge magnetoplasmon in the quantum Hall effect regime: We present the microscopic treatment of edge magnetoplasmons (EMPs) for the\nregime of not-too-low temperatures defined by the condition $\\hbar\n\\omega_{c}\\gg k_{B}T\\gg \\hbar v_{g}/2\\ell_{0}$, where $v_{g}$ is the group\nvelocity of the edge states, $\\ell_{0}=\\sqrt{\\hbar /m^{\\ast}\\omega_{c}}$ is the\nmagnetic length and $\\omega_{c}$ is the cyclotron frequency. We find a weakly\ndamped symmetric mode, named helical edge magnetoplasmon, which is localized at\nthe edge states region for filling factors $\\nu =1, 2$ and \\textit{very strong\ndissipation} $\\eta_{T}=\\xi /k_{x}\\ell_{T}\\agt\\ln (1/k_{x}\\ell_{T})\\gg 1$, where\nthe characteristic length $\\ell_{T}=k_{B}T\\ell_{0}^{2}/\\hbar v_{g}\\gg\n\\ell_{0}/2$ with $\\xi $ being the ratio of the local transverse conductivity to\nthe local Hall conductivity at the edge states and $k_{x}$ is the wave vector\nalong the edge; here other EMP modes are strongly damped. The spatial structure\nof the helical edge magnetoplasmon, transverse to the edge, is strongly\nmodified as the wave propagates along the edge. In the regime of \\textit{weak\ndissipation}, $\\eta_{T}\\ll 1$, we obtain exactly the damping of the fundamental\nmode as a function of $k_{x}$. For $\\nu=4$ and weak dissipation we find that\nthe fundamental modes of $n=0$ and $n=1$ Landau levels (LLs) are strongly\nrenormalized due to the Coulomb coupling. Renormalization of all these EMPs\ncoming from a metal gate and air half-space is studied."
    },
    {
        "anchor": "Exactly soluble model of resonant energy transfer between molecules: F\\\"orster's theory of resonant energy transfer (FRET) predicts the strength\nand range of exciton transport between separated molecules. We introduce an\nexactly soluble model for FRET which reproduces F\\\"orster's results as well as\nincorporating quantum coherence effects. As an application the model is used to\nanalyze a system composed of quantum dots and the protein bacteriorhodopsin.",
        "positive": "Interband characterization and electronic transport control of\n  nanoscaled GeTe/Sb$_2$Te$_3$ superlattices: The extraordinary electronic and optical properties of the\ncrystal-to-amorphous transition in phase-change materials led to important\ndevelopments in memory applications. A promising outlook is offered by\nnanoscaling such phase-change structures. Following this research line, we\nstudy the interband optical transmission spectra of nanoscaled\nGeTe/Sb$_2$Te$_3$ chalcogenide superlattice films. We determine, for films with\nvarying stacking sequence and growth methods, the density and scattering time\nof the free electrons, and the characteristics of the valence-to-conduction\ntransition. It is found that the free electron density decreases with\nincreasing GeTe content, for sub-layer thickness below $\\sim$3 nm. A simple\nband model analysis suggests that GeTe and Sb$_2$Te$_3$ layers mix, forming a\nstandard GeSbTe alloy buffer layer. We show that it is possible to control the\nelectronic transport properties of the films by properly choosing the\ndeposition layer thickness and we derive a model for arbitrary film stacks."
    },
    {
        "anchor": "Single photon controlled steady state electron transport through a\n  resonance DQD-Cavity system in a strong coupling regime: We perform theoretical calculations to study steady-state electron transport\nin a double quantum dot, DQD, coupled to a quantized cavity photon field both\nin resonance and off-resonance regimes considering weak and strong coupling. In\nthe resonant strong coupling regime, photon exchanges between the energy states\nof the DQD and the cavity are found reflecting multiple Rabi-resonances. The\nelectron occupation of the states and the transport current can be smoothly\nincreased by tuning the cavity-environment coupling strength. Making the system\noff-resonant, but still in the strong coupling regime, the photon exchange is\ndiminished and the electron occupation of the system and the transport current\nthrough it are prominent for high cavity-environment coupling strength. In the\nweak coupling regime between the DQD and the cavity, the system has almost the\nsame response in the resonant and the off-resonant regimes at high values of\nthe cavity-environment coupling strength.",
        "positive": "A spin-boson thermal rectifier: Rectification of heat transfer in nanodevices can be realized by combining\nthe system inherent anharmonicity with structural asymmetry. we analyze this\nphenomenon within the simplest anharmonic system -a spin-boson nanojunction\nmodel. We consider two variants of the model that yield, for the first time,\nanalytical solutions: a linear separable model in which the heat reservoirs\ncontribute additively, and a non-separable model suitable for a stronger\nsystem-bath interaction. Both models show asymmetric (rectifying) heat\nconduction when the couplings to the heat reservoirs are different."
    },
    {
        "anchor": "Real-space formulation of topology for disordered Rice-Mele chains\n  without chiral symmetry: In this paper, we derive a real-space topological invariant that involves all\nenergy states in the system. This global invariant, denoted by $Q$, is always\nquantized to be 0 or 1, independent of symmetries. In terms of $Q$, we\nnumerically investigate topological properties of the nonchiral Rice-Mele model\nincluding random onsite potentials to show that nontrivial bulk topology is\nsustained for weak enough disorder. In this regime, a finite spectral gap\npersists, and then $Q$ is definitely identified. We also consider sublattice\npolarization of disorder potentials. In this case, the energy spectrum retains\na gap regardless of disorder strength so that $Q$ is unaffected by disorder.\nThis implies that bulk topology remains intact as long as the spectral gap\nopens.",
        "positive": "Spin resonance linewidths of bismuth donors in silicon coupled to planar\n  microresonators: Ensembles of bismuth donor spins in silicon are promising storage elements\nfor microwave quantum memories due to their long coherence times which exceed\nseconds. Operating an efficient quantum memory requires achieving critical\ncoupling between the spin ensemble and a suitable high-quality factor resonator\n-- this in turn requires a thorough understanding of the lineshapes for the\nrelevant spin resonance transitions, particularly considering the influence of\nthe resonator itself on line broadening. Here, we present pulsed electron spin\nresonance measurements of ensembles of bismuth donors in natural silicon, above\nwhich niobium superconducting resonators have been patterned. By studying spin\ntransitions across a range of frequencies and fields we identify distinct line\nbroadening mechanisms, and in particular those which can be suppressed by\noperating at magnetic-field-insensitive `clock transitions'. Given the donor\nconcentrations and resonator used here, we measure a cooperativity $C\\sim 0.2$\nand based on our findings we discuss a route to achieve unit cooperativity, as\nrequired for a quantum memory."
    },
    {
        "anchor": "Magneto-electronic properties of twisted bilayer graphene system: The generalized tight-binding model is developed to investigate the\nmagneto-electronic properties in twisted bilayer graphene system. All the\ninterlayer and intralayer atomic interactions are included in the Moire\nsuperlattice. The twisted bilayer graphene system is a zero-gap semiconductor\nwith double-degenerate Dirac-cone structures, and saddle-point energy\ndispersions appearing at low energies for cases of small twisting angles. There\nexist rich and unique magnetic quantization phenomena, in which many\nLandau-level subgroups are induced due to specific Moire zone folding through\nmodulating the various stacking angles. The Landau-level spectrum shows\nhybridized characteristics associated with the those in monolayer, and AA $\\&$\nAB stackings. The complex relations among the different sublattices on the same\nand different graphene layers are explored in detail.",
        "positive": "Enhanced spin injection in molecularly functionalized graphene via\n  ultra-thin oxide barriers: Realisation of practical spintronic devices relies on the ability to create\nand detect pure spin currents. In graphene-based spin valves this is usually\nachieved by injection of spin-polarized electrons from ferromagnetic contacts\nvia a tunnel barrier, with Al2O3 and MgO used most widely as barrier materials.\nHowever, the requirement to make these barriers sufficiently thin often leads\nto pinholes and low contact resistances which in turn results in low spin\ninjection efficiencies, typically 5% at room temperature, due to the so-called\nresistance mismatch problem. Here we demonstrate an alternative approach to\nfabricate ultra-thin tunnel barrier contacts to graphene. We show that\nlaser-assisted chemical functionalization of graphene with sp3-bonded phenyl\ngroups effectively provides a seed layer for growth of ultrathin Al2O3 films,\nensuring smooth, high quality tunnel barriers and an enhanced spin injection\nefficiency. Importantly, the effect of functionalization on spin transport in\nthe graphene channel itself is relatively weak, so that the enhanced spin\ninjection dominates and leads to an order of magnitude increase in spin\nsignals. Furthermore, spatial control of functionalization using a focused\nlaser beam and lithographic techniques can in principle be used to limit\nfunctionalization to contact areas only, further reducing the effect on the\ngraphene channel. Our results open a new route towards circumventing the\nresistance mismatch problem in graphene-based spintronic devices based on the\neasily available and highly stable Al2O3, and facilitate a step forward in the\ndevelopment of their practical applications."
    },
    {
        "anchor": "Strong coupling of microwave photons to antiferromagnetic fluctuations\n  in an organic magnet: Coupling between a crystal of di(phenyl)-(2,4,6-trinitrophenyl)iminoazanium\nradicals and a superconducting microwave resonator is investigated in a circuit\nquantum electrodynamics (circuit QED) architecture. The crystal exhibits\nparamagnetic behavior above 4~K, with antiferromagnetic correlations appearing\nbelow this temperature, and we demonstrate strong coupling at base temperature.\nThe magnetic resonance acquires a field angle dependence as the crystal is\ncooled down, indicating anisotropy of the exchange interactions. These results\nshow that multispin modes in organic crystals are suitable for circuit QED,\noffering a platform for their coherent manipulation. They also utilize the\ncircuit QED architecture as a way to probe spin correlations at low\ntemperature.",
        "positive": "Klein collimation by rippled graphene superlattice: The hybridization of $\\sigma$ and $\\pi$ orbitals of carbon atoms in graphene\ndepends on the surface curvature. Considering a single junction between flat\nand rippled graphene subsystems, it is found an accumulation of charge in the\nrippled subsystem due to Klein penetration phenomenon that gives rise to n-p\njunction. Using this fact, we show that the momentum distribution of electrons\nin ballisitically propagating beam can be selective without a waveguide, or\nexternal electric, and/or magnetic fields in graphene strip under\nexperimentally feasible one-dimensional periodic potential. Such a potential is\ncreated with the aid of superlattice that consists of periodically repeated\ngraphene pieces withdifferent hybridizations of carbon orbits, produced by\nvariation of the graphene surface curvature. The charge redistribution and\nselected transmission of electrons, caused by the superlattice, allows to\ncontrol the electron focusing in the considered system by simply changing the\nelement properties in the superlattice"
    },
    {
        "anchor": "Anomalous Quantum Oscillations of Interacting Electron-hole Gases in\n  Inverted Type-II InAs/GaSb Quantum Wells: We report magneto-transport studies of InAs/GaSb bilayer quantum wells in a\nregime where the interlayer tunneling between the electron and hole gases is\nsuppressed. When the chemical potential is tuned close to the charge neutrality\npoint, we observe anomalous quantum oscillations that are inversely periodic in\nmagnetic field and that have an extremely high frequency despite the highly\ninsulating regime where they are observed. The seemingly contradictory\ncoexistence of a high sheet resistance and high frequency quantum oscillations\nin the charge neutrality regime cannot be understood within the single-particle\npicture. We propose an interpretation that attributes our experimental\nobservation to the Coulomb drag between the electron and hole gases, thus\nproviding strong evidence of the significance of Coulomb interaction in this\ntopological insulator.",
        "positive": "Coulomb blockade and Quantum Critical Points in Quantum Dots: An ultrasmall quantum dot coupled to a lead and to a quantum box (a large\nquantum dot) is investigated. Tuning the tunneling amplitudes to the lead and\nbox, we find a line of unstable non-Fermi-liquid fixed points as function of\nthe gate potentials of the quantum dots, extending to arbitrary charging\nenergies on the small and large quantum dots. These quantum-critical fixed\npoints possess a finite residual entropy. They govern the cross over from one\nFermi-liquid regime to another, characterized by distinct (high and low)\nconductance values."
    },
    {
        "anchor": "Magnon Interference Tunneling Spectroscopy as a Probe of 2D Magnetism: Probing two-dimensional single-layer quantum magnets remains a significant\nchallenge. In this letter, we propose exploiting tunneling spectroscopy in the\npresence of magnetic impurities to obtain information about the magnon\ndispersion relations in analogy to quasiparticle interference in non-magnetic\nmaterials. We show this technique can be used to establish the dispersion\nrelations even for frustrated magnets, where the presence of an impurity\ngenerally leads to a nontrivial spin texture. Finally, we consider the problem\nof establishing Chern magnon bands in 2D magnets showing how tuneable\nimpurities allow probing the nature of the surface states.",
        "positive": "Shear and Layer Breathing Modes in Multilayer MoS2: We study by Raman scattering the shear and layer breathing modes in\nmultilayer MoS2. These are identified by polarization measurements and symmetry\nanalysis. Their positions change with the number of layers, with different\nscaling for odd and even layers. A chain model explains the results, with\ngeneral applicability to any layered material, and allows one to monitor their\nthickness."
    },
    {
        "anchor": "Time-Reversal Invariant Topological Superconductivity Induced by\n  Repulsive Interactions in Quantum Wires: We consider a model for a one-dimensional quantum wire with Rashba spin-orbit\ncoupling and repulsive interactions, proximity coupled to a conventional s-wave\nsuperconductor. Using a combination of Hartree-Fock and density matrix\nrenormalization group calculations, we show that for sufficiently strong\ninteractions in the wire, a time-reversal invariant topological superconducting\nphase can be stabilized in the absence of an external magnetic field. This\nphase supports two zero-energy Majorana bound states at each end, which are\nprotected by time-reversal symmetry. The mechanism for the formation of this\nphase is a reversal of the sign of the effective pair potential in the wire,\ndue to the repulsive interactions. We calculate the differential conductance\ninto the wire and its dependence on an applied magnetic field using the\nscattering-matrix formalism. The behavior of the zero-bias anomaly as a\nfunction of the field direction can serve as a distinct experimental signature\nof the topological phase.",
        "positive": "Strongly nonlinear thermovoltage and heat dissipation in interacting\n  quantum dots: We investigate the nonlinear regime of charge and energy transport through\nCoulomb-blockaded quantum dots. We discuss crossed effects that arise when\nelectrons move in response to thermal gradients (Seebeck effect) or energy\nflows in reaction to voltage differences (Peltier effect). We find that the\ndifferential thermoelectric conductance shows a characteristic Coulomb\nbutterfly structure due to charging effects. Importantly, we show that\nexperimentally observed thermovoltage zeros are caused by the activation of\nCoulomb resonances at large thermal shifts. Furthermore, the power dissipation\nasymmetry between the two attached electrodes can be manipulated with the\napplied voltage, which has implications for the efficient design of nanoscale\ncoolers."
    },
    {
        "anchor": "Stress-Induced Variations in the Stiffness of Micro- and Nanocantilever\n  Beams: The effect of surface stress on the stiffness of cantilever beams remains an\noutstanding problem in the physical sciences. While numerous experimental\nstudies report significant stiffness change due to surface stress, theoretical\npredictions are unable to rigorously and quantitatively reconcile these\nobservations. In this Letter, we present the first controlled measurements of\nstress-induced change in cantilever stiffness with commensurate theoretical\nquantification. Simultaneous measurements are also performed on equivalent\nclamped-clamped beams. All experimental results are quantitatively and\naccurately predicted using elasticity theory. We also present conclusive\nexperimental evidence for invalidity of the longstanding and unphysical axial\nforce model, which has been widely applied to interpret measurements using\ncantilever beams. Our findings will be of value in the development of micro-\nand nanoscale resonant mechanical sensors.",
        "positive": "Floquet-Engineered Valleytronics in Dirac Systems: Valley degrees of freedom offer a potential resource for quantum information\nprocessing if they can be effectively controlled. We discuss an optical\napproach to this problem in which intense light breaks electronic symmetries of\na two-dimensional Dirac material. The resulting quasienergy structures may then\ndiffer for different valleys, so that the Floquet physics of the system can be\nexploited to produce highly polarized valley currents. This physics can be\nutilized to realize a valley valve whose behavior is determined optically. We\npropose a concrete way to achieve such valleytronics in graphene as well as in\na simple model of an inversion-symmetry broken Dirac material. We study the\neffect numerically and demonstrate its robustness against moderate disorder and\nsmall deviations in optical parameters."
    },
    {
        "anchor": "Visualizing Poiseuille flow of hydrodynamic electrons: Hydrodynamics is a general description for the flow of a fluid, and is\nexpected to hold even for fundamental particles such as electrons when\ninter-particle interactions dominate. While various aspects of electron\nhydrodynamics were revealed in recent experiments, the fundamental spatial\nstructure of hydrodynamic electrons, the Poiseuille flow profile, has remained\nelusive. In this work, we provide the first real-space imaging of Poiseuille\nflow of an electronic fluid, as well as visualization of its evolution from\nballistic flow. Utilizing a scanning nanotube single electron transistor, we\nimage the Hall voltage of electronic flow through channels of high-mobility\ngraphene. We find that the profile of the Hall field across the channel is a\nkey physical quantity for distinguishing ballistic from hydrodynamic flow. We\nimage the transition from flat, ballistic field profiles at low temperature\ninto parabolic field profiles at elevated temperatures, which is the hallmark\nof Poiseuille flow. The curvature of the imaged profiles is qualitatively\nreproduced by Boltzmann calculations, which allow us to create a 'phase\ndiagram' that characterizes the electron flow regimes. Our results provide\nlong-sought, direct confirmation of Poiseuille flow in the solid state, and\nenable a new approach for exploring the rich physics of interacting electrons\nin real space.",
        "positive": "Electrically tunable magnetoplasmons in a monolayer of silicene or\n  germanene: We theoretically study electrically tunable magnetoplasmons in a monolayer of\nsilicene or germanene. We derive the dynamical response function and take into\naccount the effects of strong spin-orbit coupling (SOC) and of an external\nelectric filed $E_z$ perpendicular to the plane of the buckled\nsilicene/germanene. Employing the random-phase approximation we analyze the\nmagnetoplasmon spectrum. The dispersion relation has the same form as in a\ntwo-dimensional electron gas with the cyclotron and plasma frequencies modified\ndue to the SOC and the field $E_z$. In the absence of SOC and $E_z$, our\nresults agree well with recent experiments on graphene. The predicted effects\ncould be tested by experiments similar to those on graphene and would be useful\nfor future spintronics and optoelectronic devices."
    },
    {
        "anchor": "Temperature dependence of the resistance of metallic nanowires (diameter\n  $\\geq$ 15 nm): Applicability of Bloch-Gr\u00fcneisen theorem: We have measured the resistances (and resistivities) of Ag and Cu nanowires\nof diameters ranging from 15nm to 200nm in the temperature range 4.2K-300K with\nthe specific aim to assess the applicability of the Bloch-Gr\\\"{u}neisen formula\nfor electron phonon resistivity in these nanowires. The wires were grown within\npolymeric templates by electrodeposition. We find that in all the samples the\nresistance reaches a residual value at T=4.2K and the temperature dependence of\nresistance can be fitted to the Bloch-Gr\\\"{u}neisen formula in the entire\ntemperature range with a well defined transport Debye temperature\n($\\Theta_{R}$). The value of Debye temperature obtained from the fits lie\nwithin 8% of the bulk value for Ag wires of diameter 15nm while for Cu\nnanowires of the same diameter the Debye temperature is significantly lesser\nthan the bulk value. The electron-phonon coupling constants (measured by\n$\\alpha_{el-ph}$ or $\\alpha_{R}$) in the nanowires were found to have the same\nvalue as that of the bulk. The resistivities of the wires were seen to increase\nas the wire diameter was decreased. This increase in the resistivity of the\nwires may be attributed to surface scattering of conduction electrons. The\nspecularity p was estimated to be about 0.5. The observed results allow us to\nobtain the resistivities exactly from the resistance and gives us a method of\nobtaining the exact numbers of wires within the measured array (grown within\nthe template).",
        "positive": "Spin Manipulation in Graphene by Chemically-Induced Sublattice\n  Pseudospin Polarization: Spin manipulation is one of the most critical challenges to realize\nspin-based logic devices and spintronic circuits. Graphene has been heralded as\nan ideal material to achieve spin manipulation but so far new paradigms and\ndemonstrators are limited. Here we show that certain impurities such as\nfluorine ad-atoms, which locally break sublattice symmetry without the\nformation of strong magnetic moment, could result in a remarkable variability\nof spin transport characteristics. The impurity resonance level is found to be\nassociated with a long range sublattice pseudospin polarization, which by\nlocally decoupling spin and pseudospin dynamics, provokes a huge spin lifetime\nelectron-hole asymmetry. In the dilute impurity limit, spin lifetimes could be\ntuned electrostatically from hundred picoseconds to several nanoseconds,\nproviding a protocol to chemically engineer an unprecedented spin device\nfunctionality."
    },
    {
        "anchor": "Type-II topological metals: Topological metals (TMs) are a kind of special metallic materials, which\nfeature nontrivial band crossings near the Fermi energy, giving rise to\npeculiar quasiparticle excitations. TMs can be classified based on the\ncharacteristics of these band crossings. For example, according to the\ndimensionality of the crossing, TMs can be classified into nodal-point,\nnodal-line, and nodal-surface metals. Another important property is the type of\ndispersion. According to degree of the tilt of the local dispersion around the\ncrossing, we have type-I and type-II dispersions. This leads to significant\ndistinctions in the physical properties of the materials, owing to their\ncontrasting Fermi surface topologies. In this article, we briefly review the\nrecent advances in this research direction, focusing on the concepts, the\nphysical properties, and the material realizations of the type-II nodal-point\nand nodal-line TMs.",
        "positive": "Voltage Controlled Energy Efficient Domain Wall Synapses with Stochastic\n  Distribution of Quantized Weights in the Presence of Thermal Noise and Edge\n  Roughness: We propose energy efficient strain control of domain wall (DW) in a\nperpendicularly magnetized nanoscale racetrack on a piezoelectric substrate\nthat can implement multi state synapse to be utilized in neuromorphic computing\nplatforms. In conjunction with SOT from to a current flowing in the heavy metal\nlayer, strain is generated by applying a voltage across the piezoelectric. Such\na strain is mechanically transferred to the racetrack and modulates the\nPerpendicular Magnetic Anisotropy (PMA). When different voltages are applied\n(i.e. different strains are generated), it can translate the DW to different\ndistances for the same current which implements different synaptic weights. We\nhave shown using micromagnetic simulations that 5-state and 3-state synapse can\nbe implemented in a racetrack that is modeled with natural edge roughness and\nroom temperature thermal noise. Such strain-controlled synapse has an energy\nconsumption of few fJs and could thus be very attractive to implement\nenergy-efficient quantized neural networks, which has been shown recently to\nachieve near equivalent classification accuracy to the full-precision neural\nnetworks."
    },
    {
        "anchor": "Giant Nonlocality near the Dirac Point in Graphene: Transport measurements have been a powerful tool for uncovering new\nelectronic phenomena in graphene. We report nonlocal measurements performed in\nthe Hall bar geometry with voltage probes far away from the classical path of\ncharge flow. We observe a large nonlocal response near the Dirac point in\nfields as low as 0.1T, which persists up to room temperature. The nonlocality\nis consistent with the long-range flavor currents induced by lifting of\nspin/valley degeneracy. The effect is expected to contribute strongly to all\nmagnetotransport phenomena near the neutrality point.",
        "positive": "Electron and hole states in quantum-dot quantum wells within a spherical\n  8-band model: In order to study heterostructures composed both of materials with strongly\ndifferent parameters and of materials with narrow band gaps, we have developed\nan approach, which combines the spherical 8-band effective-mass Hamiltonian and\nthe Burt's envelope function representation. Using this method, electron and\nhole states are calculated in CdS/HgS/CdS/H_2O and CdTe/HgTe/CdTe/H_2O\nquantum-dot quantum-well heterostructures. Radial components of the wave\nfunctions of the lowest S and P electron and hole states in typical quantum-dot\nquantum wells (QDQWs) are presented as a function of radius. The 6-band-hole\ncomponents of the radial wave functions of an electron in the 8-band model have\namplitudes comparable with the amplitude of the corresponding 2-band-electron\ncomponent. This is a consequence of the coupling between the conduction and\nvalence bands, which gives a strong nonparabolicity of the conduction band. At\nthe same time, the 2-band-electron component of the radial wave functions of a\nhole in the 8-band model is small compared with the amplitudes of the\ncorresponding 6-band-hole components. It is shown that in the CdS/HgS/CdS/H_2O\nQDQW holes in the lowest states are strongly localized in the well region\n(HgS). On the contrary, electrons in this QDQW and both electron and holes in\nthe CdTe/HgTe/CdTe/H_2O QDQW are distributed through the entire dot. The\nimportance of the developed theory for QDQWs is proven by the fact that in\ncontrast to our rigorous 8-band model, there appear spurious states within the\ncommonly used symmetrized 8-band model."
    },
    {
        "anchor": "Transmutation from Skyrmions to Half-Solitons Driven by the Nonlinear\n  Optical Spin-Hall Effect: We show that the polarization domains generated in the linear optical\nspin-Hall effect by the analog of spin-orbit interaction for exciton-polaritons\nare associated with the formation of a Skyrmion lattice. In the non-linear\nregime, the spin anisotropy of the polariton-polariton interactions results in\na spatial compression of the spin domains and in an abrupt transformation of\nthe Skyrmions into half-solitons, associated with both the focalization of the\nspin currents and the emergence of a strongly anisotropic emission pattern.",
        "positive": "Complex magnetic structure and spin waves of the noncollinear\n  antiferromagnet Mn5Si3: The investigations of the interconnection between micro- and macroscopic\nproperties of materials hosting noncollinear antiferromagnetic ground states\nare challenging. These forefront studies are crucial for unraveling the\nunderlying mechanisms at play, which may prove beneficial in designing cutting\nedge multifunctional materials for future applications. In this context, Mn5Si3\nhas regained scientific interest since it displays an unusual and complex\nground state, which is considered to be the origin of the anomalous transport\nand thermodynamic properties that it exhibits. Here, we report the magnetic\nexchange couplings of the noncollinear antiferromagnetic phase of Mn5Si3 using\ninelastic neutron scattering measurements and density functional theory\ncalculations. We determine the ground-state spin configuration and compute its\nmagnon dispersion relations which are in good agreement with the ones obtained\nexperimentally. Furthermore, we investigate the evolution of the spin texture\nunder the application of an external magnetic field to demonstrate\ntheoretically the multiple field-induced phase transitions that Mn5Si3\nundergoes. Finally, we model the stability of some of the material's magnetic\nmoments under a magnetic field and we find that very susceptible magnetic\nmoments in a frustrated arrangement can be tuned by the field."
    },
    {
        "anchor": "Crossover from Electronic to Atomic Shell Structure in Alkali Metal\n  Nanowires: After making a cold weld by pressing two clean metal surfaces together, upon\ngradually separating the two pieces a metallic nanowire is formed, which\nprogressively thins down to a single atom before contact is lost. In previous\nexperiments [1,2] we have observed that the stability of such nanowires is\ninfluenced by electronic shell filling effects, in analogy to shell effects in\nmetal clusters [3]. For sodium and potassium at larger diameters there is a\ncrossover to crystalline wires with shell-closings corresponding to the\ncompletion of additional atomic layers. This observation completes the analogy\nbetween shell effects observed for clusters and nanowires.",
        "positive": "Spin waves in doped graphene: a time-dependent spin-density-functional\n  approach to collective excitations in paramagnetic two-dimensional Dirac\n  fermion gases: In spin-polarized itinerant electron systems, collective spin-wave modes\narise from dynamical exchange and correlation (xc) effects. We here consider\nspin waves in doped paramagnetic graphene with adjustable Zeeman-type band\nsplitting. The spin waves are described using time-dependent\nspin-density-functional response theory, treating dynamical xc effects within\nthe Slater and Singwi-Tosi-Land-Sjolander approximations. We obtain spin-wave\ndispersions and spin stiffnesses as a function of doping and spin polarization,\nand discuss prospects for their experimental observation."
    },
    {
        "anchor": "Theoretical polarization dependence of the two-phonon double-resonant\n  Raman spectra of graphene: The experimental Raman spectra of graphene exhibit a few intense two-phonon\nbands, which are enhanced through double-resonant scattering processes. Though\nthere are many theoretical papers on this topic, none of them predicts the\nspectra within a single model. Here, we present results for the two-phonon\nRaman spectra of graphene calculated by means of the quantum perturbation\ntheory. The electron and phonon dispersions, electronic lifetime,\nelectron-photon and electron-phonon matrix elements, are all obtained within a\ndensity-functional-theory-based non-orthogonal tight-binding model. We study\nsystematically the overtone and combination two-phonon Raman bands, and, in\nparticular, the energy and polarization dependence of their Raman shift and\nintensity. We find that the ratio of the integrated intensities for parallel\nand cross polarized light for all two-phonon bands is between 0.33 and 0.42.\nOur results are in good agreement with the available experimental data.",
        "positive": "Chiral properties of graphene h-BN hybrid systems: The application of the chiral decomposition procedure to hybrid graphene h-BN\nsystems revealed rules for the partition of the system into effective\nsubsystems being bilayers plus monolayer in case the number of layers is odd.\nThree types of subsystems have been detected namely purely graphene bilayers\nand monolayers, mixed bilayers and pure h-BN monolayers depending on the hybrid\ncomposition. The effective parameters characterizing these chiral subsystems\nconsist of the interlayer couplings and on-site potentials which shows the\nmechanism of compensation of the asymmetry introduced into the system by h-BN\nlayers. For illustration, we provide a pedagogical overview about chiral\ntunneling in graphene subsystems (MLG, BLG) present in hybrid with one h-BN\nlayer. We have established the parameter ranges for which the characteristic\nfeatures in the spectrum are observed, such as Fabry-P\\'erot resonances in the\ncase of MLG and \"magic angles\" in the case of effective BLG. We also consider\ndifferent hybrid stacking in order to indicate effective systems with the\ndesired properties required in the electronic and spintronic applications."
    },
    {
        "anchor": "Macroscopic resonant tunneling of magnetic flux: We have developed a quantitative theory of resonant tunneling of magnetic\nflux between discrete macroscopically distinct quantum states in SQUID systems.\nThe theory is based on the standard density-matrix approach. Its new elements\ninclude the discussion of the two different relaxation mechanisms that exist\nfor the double-well potential, and description of the ``photon-assisted''\ntunneling driven by external rf radiation. It is shown that in the case of\ncoherent flux dynamics, rf radiation should lead to splitting of the peaks of\nresonant flux tunneling, indicating that the resonant tunneling is a convenient\ntool for studying macroscopic quantum coherence of flux.",
        "positive": "Manipulating the voltage drop in graphene nanojunctions using a gate\n  potential: Graphene is an attractive electrode material to contact nanostructures down\nto the molecular scale since it can be gated electrostatically. Gating can be\nused to control the doping and the energy level alignment in the nanojunction,\nthereby influencing its conductance. Here we investigate the impact of\nelectrostatic gating in nanojunctions between graphene electrodes operating at\nfinite bias. Using first principles quantum transport simulations, we show that\nthe voltage drop across \\emph{symmetric} junctions changes dramatically and\ncontrollably in gated systems compared to non-gated junctions. In particular,\nfor \\emph{p}-type(\\emph{n}-type) carriers the voltage drop is located close to\nthe electrode with positive(negative) polarity, i.e. the potential of the\njunction is pinned to the negative(positive) electrode. We trace this behaviour\nback to the vanishing density of states of graphene in the proximity of the\nDirac point. Due to the electrostatic gating, each electrode exposes different\ndensity of states in the bias window between the two different electrode Fermi\nenergies, thereby leading to a non-symmetry in the voltage drop across the\ndevice. This selective pinning is found to be independent of device length when\ncarriers are induced either by the gate or dopant atoms, indicating a general\neffect for electronic circuitry based on graphene electrodes. We envision this\ncould be used to control the spatial distribution of Joule heating in graphene\nnanostructures, and possibly the chemical reaction rate around high potential\ngradients."
    },
    {
        "anchor": "Bound state energy of a Coulomb impurity in gapped bilayer graphene:\n  \"Hydrogen atom with a Mexican hat\": Application of a perpendicular electric field induces a band gap in bilayer\ngraphene, and it also creates a \"Mexican hat\" structure in the dispersion\nrelation. This structure has unusual implications for the hydrogen-like bound\nstate of an electron to a Coulomb impurity. We calculate the ground state\nenergy of this hydrogen-like state as a function of the applied interlayer\nvoltage and the effective fine structure constant. Unlike in the normal\nhydrogen atom, the resulting wavefunction has many nodes even in the ground\nstate. Further, the electron state undergoes \"atomic collapse\" into the Dirac\ncontinuum both at small and large voltage.",
        "positive": "Dynamic characteristics of terahertz hot-electron graphene FET\n  bolometers: effect of electron cooling in channel and at side contacts: We analyze the operation of the hot-electron FET bolometers with the graphene\nchannels (GCs) and the gate barrier layers (BLs). Such bolometers use the\nthermionic emission of the hot electrons heated by incident modulated THz\nradiation. The hot electron transfer from the GC into the metal gate. As the\nTHz detectors, these bolometers can operate at room temperature. We show that\nthe response and ultimate modulation frequency of the GC-FET bolometers are\ndetermined by the efficiency of the hot-electron energy transfer to the lattice\nand the GC side contacts due to the 2DEG lateral thermal conductance. The\ndependences of these mechanisms on the band structure and geometrical\nparameters open the way for the GC-FET bolometers optimization, in particular,\nfor the enhancement of the maximum modulation frequency."
    },
    {
        "anchor": "Certain exact many-body results for Hubbard model ground states testable\n  in small quantum dot arrays: We present several interesting phenomena related to flatband ferromagnetism\nin the Hubbard model. The first is a mathematical theorem stating certain\nconditions under which a flatband ferromagnetic must necessarily be degenerate\nwith a nonferromagnetic state. This theorem is generally applicable and\ngeometry-independent, but holds only for a small number of holes in an\notherwise filled band. The second phenomenon is a peculiar example where the\nintuition fails that particles prefer to doubly occupy low-energy states before\nfilling higher-energy states. Lastly, we show a pattern of ferromagnetism which\nappears in small pentagonal and hexagonal plaquettes at filling factors of\nroughly 3/10 and 1/4. These examples require only a small number of lattice\nsites, and may be observable in quantum dot arrays currently available as\nlaboratory spin qubit arrays.",
        "positive": "Dynamical properties of a nonequilibrium quantum dot close to\n  localized-delocalized quantum phase transitions: We calculate the dynamical decoherence rate and susceptibility of a\nnonequilibrium quantum dot close to the delocalized-to-localized quantum phase\ntransitions. The setup concerns a resonance-level coupled to two spinless\nfermionic baths with a finite bias voltage and an Ohmic bosonic bath\nrepresenting the dissipative environment. The system is equivalent to an\nanisotropic Kondo model.\n  As the dissipation strength increases, the system at zero temperature and\nzero bias show quantum phase transition between a conducting delocalized phase\nto an insulating localized phase. Within the nonequilibrium functional\nRenormalization Group (FRG) approach, we address the finite bias crossover in\ndynamical decoherence rate and charge susceptibility close to the phase\ntransition. We find the dynamical decoherence rate increases with increasing\nfrequency. In the delocalized phase, it shows a singularity at frequencies\nequal to positive or negative bias voltage. As the system crossovers to the\nlocalized phase, the decoherence rate at low frequencies get progressively\nsmaller and this sharp feature is gradually smeared out, leading to a single\nlinear frequency dependence. The dynamical charge susceptibility shows a\ndip-to-peak crossover across the delocalized-to-localized transition. Relevance\nof our results to the experiments is discussed."
    },
    {
        "anchor": "Tuning the Non-local Spin-Spin Interaction between Quantum Dots with a\n  Magnetic Field: We describe a device where the non-local spin-spin interaction between two\nquantum dots can be turned on and off and even changed sign with a very small\nmagnetic field. The setup consists of two quantum dots at the edge of two\ntwo-dimensional electron gases (2DEGs). The quantum dots' spins are coupled\nthrough a RKKY-like interaction mediated by the electrons in the 2DEGs. A small\nmagnetic field perpendicular to the plane of the 2DEG is used as a tuning\nparameter. When the cyclotron radius is commensurate with the interdot\ndistance, the spin-spin interaction is amplified by a few orders of magnitude.\nThe sign of the interaction is controlled by finely tuning the magnetic field.\nOur setup allows for several dots to be coupled in a linear arrangement and it\nis not restricted to nearest-neighbors interaction.",
        "positive": "Gaps tunable by electrostatic gates in strained graphene: We show that when the pseudomagnetic fields created by long wavelength\ndeformations are appropriately coupled with a scalar electric potential, a\nsignificant energy gap can emerge due to the formation of a Haldane state.\nRamifications of this physical effect are examined through the study of various\nstrain geometries commonly seen in experiments, such as strain superlattices\nand wrinkled suspended graphene. Of particular technological importance, we\nconsider setup where this gap can be tunable through electrostatic gates,\nallowing for the design of electronic devices not realizable with other\nmaterials."
    },
    {
        "anchor": "Accelerating micromagnetic and atomistic simulations using multiple GPUs: It is shown micromagnetic and atomistic spin dynamics simulations can use\nmultiple GPUs in order to reduce computation time, but also to allow for a\nlarger simulation size than is possible on a single GPU. Whilst interactions\nwhich depend on neighbouring spins, such as exchange interactions, may be\nimplemented efficiently by transferring data between GPUs using halo regions,\nor alternatively using direct memory accesses, implementing the long-range\ndemagnetizing interaction is the main difficulty in achieving good performance\nscaling, where the data transfer rate between GPUs is a significant bottleneck.\nA multi-GPU convolution algorithm is developed here, which relies on single-GPU\nFFTs executed in parallel. It is shown that even for micromagnetic simulations\nwhere the demagnetizing interaction computation time dominates, good\nperformance scaling may be achieved, with speedup factors up to 1.8, 2.5, and\n3.1, for 2, 3, and 4 GPUs respectively. The code developed here can be used for\nany number of GPUs in parallel, with performance scaling strongly dependent on\ninter-GPU data transfer rate and connection topology. This is further improved\nin micromagnetic simulations which include a spin transport solver, obtaining\nspeedup factors up to 1.96, 2.8, and 3.7, for 2, 3, and 4 GPUs respectively.\nThe best case scenario is obtained for atomistic spin dynamics simulations,\nwhere the demagnetizing interaction is implemented with spin-averaged cells.\nUsing a single workstation with 4 GPUs, it is shown atomistic spin dynamics\nsimulations with up to 1 billion spins, and atomistic Monte Carlo simulations\nwith up to 2 billion spins are possible, with a near-ideal performance scaling.",
        "positive": "Benchmarking GW against exact diagonalization for semi-empirical models: We calculate groundstate total energies and single-particle excitation\nenergies of seven pi conjugated molecules described with the semi-empirical\nPariser-Parr-Pople (PPP) model using self-consistent many-body perturbation\ntheory at the GW level and exact diagonalization. For the total energies GW\ncaptures around 65% of the groundstate correlation energy. The lowest lying\nexcitations are overscreened by GW leading to an underestimation of electron\naffinities and ionization potentials by approximately 0.15 eV corresponding to\n2.5%. One-shot G_0W_0 calculations starting from Hartree-Fock reduce the\nscreening and improve the low-lying excitation energies. The effect of the GW\nself-energy on the molecular excitation energies is shown to be similar to the\ninclusion of final state relaxations in Hartree-Fock theory. We discuss the\nbreak down of the GW approximation in systems with short range interactions\n(Hubbard models) where correlation effects dominate over screening/relaxation\neffects. Finally we illustrate the important role of the derivative\ndiscontinuity of the true exchange-correlation functional by computing the\nexact Kohn-Sham levels of benzene."
    },
    {
        "anchor": "Spin Decay in a Quantum Dot Coupled to a Quantum Point Contact: We consider a mechanism of spin decay for an electron spin in a quantum dot\ndue to coupling to a nearby quantum point contact (QPC) with and without an\napplied bias voltage. The coupling of spin to charge is induced by the\nspin-orbit interaction in the presence of a magnetic field. We perform a\nmicroscopic calculation of the effective Hamiltonian coupling constants to\nobtain the QPC-induced spin relaxation and decoherence rates in a realistic\nsystem. This rate is shown to be proportional to the shot noise of the QPC in\nthe regime of large bias voltage and scales as $a^{-6}$ where $a$ is the\ndistance between the quantum dot and the QPC. We find that, for some specific\norientations of the setup with respect to the crystallographic axes, the\nQPC-induced spin relaxation and decoherence rates vanish, while the charge\nsensitivity of the QPC is not changed. This result can be used in experiments\nto minimize QPC-induced spin decay in read-out schemes.",
        "positive": "Band structure and topological property of twisted double bilayer\n  graphenes: We study the electronic band structure and the topological property of the\ntwisted double bilayer graphene, or a pair of AB-stacked bilayer graphenes\nrotationally stacked on top of each other. We consider two different\narrangements, AB-AB and AB-BA, which differ in the relative orientation. For\neach system, we calculate the energy band and the valley Chern number using the\ncontinuum Hamiltonian. We show that the AB-AB and the AB-BA have similar band\nstructures, while the Chern numbers associated with the corresponding bands are\ncompletely different. In the absence of the perpendicular electric field, in\nparticular, the AB-AB system is a trivial insulator when the Fermi energy is in\na gap, while the AB-BA is a valley Hall insulator. Also, the lowest electron\nand hole bands of the AB-AB are entangled by the symmetry protected band\ntouching points, while they are separated in the AB-BA. In both cases, the\nperpendicular electric field immediately opens an energy gap at the charge\nneutral point, where the electron branch becomes much narrower than the hole\nbranch, due to the significant electron-hole asymmetry."
    },
    {
        "anchor": "Approach to steady state transport in nanoscale conductors: We show, using a tight-binding model and time-dependent density-functional\ntheory, that a quasi-steady state current can be established dynamically in a\nfinite nanoscale junction without any inelastic effects. This is simply due to\nthe geometrical constriction experienced by the electron wavepackets as they\npropagate through the junction. We also show that in this closed\nnon-equilibrium system two local electron occupation functions can be defined\non each side of the nanojunction which approach Fermi distributions with\nincreasing number of atoms in the electrodes. The resultant conductance and\ncurrent-voltage characteristics at quasi-steady state are in agreement with\nthose calculated within the static scattering approach.",
        "positive": "Noise of Entangled Electrons: Bunching and Antibunching: Addressing the feasibility of quantum communication with entangled electrons\nin an interacting many-body environment, we propose an interference experiment\nusing a scattering set-up with an entangler and a beam splitter. It is shown\nthat, due to electron-electron interaction, the fidelity of the entangled\nsinglet and triplet states is reduced by z_F^2 in a conductor described by\nFermi liquid theory. We calculate the quasiparticle weight factor z_F for a\ntwo-dimensional electron system. The current noise for electronic singlet\nstates turns out to be enhanced (bunching behavior), while it is reduced for\ntriplet states (antibunching). Within standard scattering theory, we find that\nthe Fano factor (noise-to-current ratio) for singlets is twice as large as for\nindependent classical particles and is reduced to zero for triplets."
    },
    {
        "anchor": "Graphene Quantum Dot as a Probe for DNA Nucleobase Detection: A First\n  Principle Study: In this study, structural stability, electronic, optical and vibrational\nproperties of DNA nucleobase adsorbed Graphene Quantum Dot (GQD) has been\ninvestigated using density functional theory. Based on state-of-art electronic\nstructure calculations, we predict order of GQD sensitivity for DNA nucleobase\nas Thymine > Cytosine > Guanine > Adenine. An interaction of GQD with DNA\nnucleobase leads to modulation in electronic energy gap. Our calculated UV/vis\nand IR vibrational spectra show unique spectral band that can be used\nfingerprints in next generation DNA sequencing diagnostics.",
        "positive": "Atomic antiferromagnetic domain wall propagation beyond the relativistic\n  limit: We theoretically investigate the dynamics of atomic domain walls (DWs) in\nantiferromagnets driven by a spin-orbit field. For a DW with the width of a few\nlattice constants, we identify a Peierls-like pinning effect, with the\ndepinning field exponentially decaying with the DW width, so that a spin-orbit\nfield moderately larger than the threshold can drive the propagation of an\natomic DW in a step-wise manner. For a broad DW, the Peierls pinning is\nnegligibly small. However, the external spin-orbit field can induce a fast DW\npropagation, accompanied by a significant shrinking of its width down to atomic\nscales. Before stepping into the pinning region, noticeable spin waves are\nemitted at the tail of the DW. The spin-wave emission event not only broadens\nthe effective width of the DW, but also pushes the DW velocity over the\nmagnonic barrier, which is generally believed to be the relativistic limit of\nthe DW speed. While the existing dynamic theory based on the continuum\napproximation fails in the atomic scale, we develop an energy conversion theory\nto interpret the DW dynamics beyond the relativistic limit."
    },
    {
        "anchor": "Developing a Chemical and Structural Understanding of the Surface Oxide\n  in a Niobium Superconducting Qubit: Superconducting thin films of niobium have been extensively employed in\ntransmon qubit architectures. Although these architectures have demonstrated\nremarkable improvements in recent years, further improvements in performance\nthrough materials engineering will aid in large-scale deployment. Here, we use\ninformation retrieved from secondary ion mass spectrometry and electron\nmicroscopy to conduct a detailed assessment of the surface oxide that forms in\nambient conditions for transmon test qubit devices patterned from a niobium\nfilm. We observe that this oxide exhibits a varying stoichiometry with NbO and\nNbO$_2$ found closer to the niobium film and Nb$_2$O$_5$ found closer to the\nsurface. In terms of structural analysis, we find that the Nb$_2$O$_5$ region\nis semicrystalline in nature and exhibits randomly oriented grains on the order\nof 1-2 nm corresponding to monoclinic N-Nb$_2$O$_5$ that are dispersed\nthroughout an amorphous matrix. Using fluctuation electron microscopy, we are\nable to map the relative crystallinity in the Nb$_2$O$_5$ region with nanometer\nspatial resolution. Through this correlative method, we observe that amorphous\nregions are more likely to contain oxygen vacancies and exhibit weaker bonds\nbetween the niobium and oxygen atoms. Based on these findings, we expect that\noxygen vacancies likely serve as a decoherence mechanism in quantum systems.",
        "positive": "Geometric Thermoelectric Pump: Energy Harvesting beyond Seebeck and\n  Pyroelectric Effects: Thermal-electric conversion is crucial for smart energy control and\nharvesting, such as thermal sensing and waste heat recovering. So far, people\nare aware of two main ways of direct thermal-electric conversion, Seebeck and\npyroelectric effects, each with different working mechanisms, conditions and\nlimitations. Here, we report the concept of \"Geometric Thermoelectric Pump\", as\nthe third way of thermal-electric conversion beyond Seebeck and pyroelectric\neffects. In contrast to Seebeck effect that requires spatial temperature\ndifference, Geometric Thermoelectric Pump converts the time-dependent ambient\ntemperature fluctuation into electricity. Moreover, Geometric Thermoelectric\nPump does not require polar materials but applies to general conducting\nsystems, thus is also distinct from pyroelectric effect. We demonstrate that\nGeometric Thermoelectric Pump results from the temperature-fluctuation-induced\ncharge redistribution, which has a deep connection to the topological geometric\nphase in non-Hermitian dynamics, as a consequence of the fundamental\nnonequilibrium thermodynamic geometry. The findings advance our understanding\nof geometric phase induced multiple-physics-coupled pump effect and provide new\nmeans of thermal-electric energy harvesting."
    },
    {
        "anchor": "Cyclotron motion in graphene: We investigate cyclotron motion in graphene monolayers considering both the\nfull quantum dynamics and its semiclassical limit reached at high carrier\nenergies. Effects of zitterbewegung due to the two dispersion branches of the\nspectrum dominate the irregular quantum motion at low energies and are obtained\nas a systematic correction to the semiclassical case. Recent experiments are\nshown to operate in the semiclassical regime.",
        "positive": "Phonons of electronic crystals in two-dimensional semiconductor moir\u00e9\n  patterns: We theoretically studied the phonon properties of the triangular-, stripe-\nand honeycomb-type electronic crystals recently found in two-dimensional\nsemiconductor moir\\'e patterns. By analyzing the phonon dispersions, we found\nthe interaction induced lattice deformation in the zigzag-stripe crystal\nresults in a much higher dynamical stability than in the linear-stripe crystal.\nMoreover, chiral phonons with finite magnetizations and large Berry curvatures\ncan emerge in triangular and honeycomb crystals under time-reversal or\ninversion symmetry breaking. The small effective mass of the electrons allows\nthe selective and efficient generation of chiral phonons from the optical\nactivity of zone-center phonons combined with the anharmonicity, facilitating\nthe realization of the phonon Hall effect. These findings point to an exciting\nnew platform for exploring chiral phonons and the related topological phononic\ndevices."
    },
    {
        "anchor": "Partially-separated Majorana modes in a disordered medium: Focusing on the implications of recent experiments on Majorana zero modes in\nsemiconductor-superconductor (SM-SC) heterostructures, we critically examine\nthe quantization of the zero-bias differential conductance as a possible\nunambiguous signature of Majorana physics in the presence of disorder. By\nnumerically calculating the zero-bias conductance (ZBC) maps as function of\nZeeman splitting and chemical potential for different disorder realizations, we\nshow that the presence of quantized \"islands\" characterized by a ZBC value\n(approximately) equal to $2e^2/h$ and having a finite area/volume in a\nmulti-dimensional parameter space represents a unique signature of Majorana\nphysics supporting Majorana zero modes (MZMs) or partially-separated Majorana\nmodes (ps-MMs). We find that in the presence of strong disorder Majorana\nphysics only emerges locally and gives rise to ps-MMs, which, in turn, generate\nsmall quantized islands when one of the Majorana modes is located at the end of\nthe system. Observing these small islands may require sample selection and the\nsystematic scanning of a large volume in the control parameter space. Upon\ndecreasing disorder, the quantized islands increase in size and eventually\ncoalesce into large topological regions. Since the presence of MZMs localized\nat the opposite ends of the system is typically associated with large quantized\nislands, looking for MZM-induced edge-to-edge correlations is premature in the\nabsence of convincing experimental evidence for (even small) quantized islands.\nWe conclude that the observation of quantized islands demonstrates\nunambiguously the presence of the key ingredients necessary for Majorana\nphysics, provides an excellent diagnostic tool for evaluating the disorder\nstrength, and, consequently, represents the next natural milestone in the\nMajorana search.",
        "positive": "Nonlinear dynamical topological phases in Cooper-pair box array: The topological property of a system is a static property in general. For\ninstance, the topological edge state is observed by measuring the local density\nof states. In this work we propose a system whose topological property is only\nrevealed by dynamics. As a concrete example, we explore a nonlinear dynamical\ntopological phase transition revealed by a quench dynamics of a Cooper-pair box\narray connected with capacitors. It is described by coupled nonlinear\ndifferential equations due to the Josephson effect. It is trivial as far as the\nstatic system is concerned. However, the wave propagation induced by the quench\ndynamics demonstrates a rich topological phase diagram in terms of the strength\nof the input."
    },
    {
        "anchor": "Zeeman spectroscopy of excitons and hybridization of electronic states\n  in few-layer WSe$_2$, MoSe$_2$ and MoTe$_2$: Monolayers and multilayers of semiconducting transition metal dichalcogenides\n(TMDCs) offer an ideal platform to explore valley-selective physics with\npromising applications in valleytronics and information processing. Here we\nmanipulate the energetic degeneracy of the $\\mathrm{K}^+$ and $\\mathrm{K}^-$\nvalleys in few-layer TMDCs. We perform high-field magneto-reflectance\nspectroscopy on WSe$_2$, MoSe$_2$, and MoTe$_2$ crystals of thickness from\nmonolayer to the bulk limit under magnetic fields up to 30 T applied\nperpendicular to the sample plane. Because of a strong spin-layer locking, the\nground state A excitons exhibit a monolayer-like valley Zeeman splitting with a\nnegative $g$-factor, whose magnitude increases monotonically when thinning the\ncrystal down from bulk to a monolayer. Using the $\\mathbf{k\\cdot p}$\ncalculation, we demonstrate that the observed evolution of $g$-factors for\ndifferent materials is well accounted for by hybridization of electronic states\nin the $\\mathrm{K}^+$ and $\\mathrm{K}^-$ valleys. The mixing of the valence and\nconduction band states induced by the interlayer interaction decreases the\n$g$-factor magnitude with an increasing layer number. The effect is the largest\nfor MoTe$_2$, followed by MoSe$_2$, and smallest for WSe$_2$.\n  Keywords: MoSe$_2$, WSe$_2$, MoTe$_2$, valley Zeeman splitting, transition\nmetal dichalcogenides, excitons, magneto optics.",
        "positive": "Ultrafast THz probe of photo-induced polarons in lead-halide perovskites: We study the nature of photo-excited charge carriers in CsPbBr3 nanocrystal\nthin films by ultrafast optical pump - THz probe spectroscopy. We observe a\ndeviation from a pure Drude dispersion of the THz dielectric response that is\nascribed to the polaronic nature of carriers; a transient blueshift of observed\nphonon frequencies is indicative of the coupling between photogenerated charges\nand stretching-bending modes of the deformed inorganic sublattice, as confirmed\nby DFT calculations."
    },
    {
        "anchor": "Quantum confinement of zero-dimensional hybrid organic-inorganic\n  polaritons at room temperature: We report on the quantum confinement of zero-dimensional polaritons in\nperovskite-based microcavity at room temperature. Photoluminescence of discrete\npolaritonic states are observed for polariton localized in symmetric\nsphere-like defects which are spontaneously nucleated on the top dielectric\nBragg mirror. The linewidth of these confined states are found much sharper\n(almost one order of magnitude) than that of photonic modes in the perovskite\nplanar microcavity. Our results show the possibility to study organic-inorganic\ncavity polariton in confined microstructure and suggest a fabrication method to\nrealize integrated polaritonic devices operating at room temperature.",
        "positive": "Excitons in narrow-gap carbon nanotubes: We calculate the exciton binding energy in single-walled carbon nanotubes\nwith narrow band gaps, accounting for the quasi-relativistic dispersion of\nelectrons and holes. Exact analytical solutions of the quantum relativistic\ntwo-body problem are obtain for several limiting cases. We show that the\nbinding energy scales with the band gap, and conclude on the basis of the data\navailable for semiconductor nanotubes that there is no transition to an\nexcitonic insulator in quasi-metallic nanotubes and that their THz applications\nare feasible."
    },
    {
        "anchor": "Benefits of weak disorder in one dimensional topological superconductors: Majorana bound states are zero-energy modes localized at the ends of a\none-dimensional (1D) topological superconductor. Introducing disorder usually\nincreases the Majorana localization length, until eventually inducing a\ntopological phase transition to a trivial phase. In this work we show that in\nsome cases weak disorder causes the Majorana localization length to decrease,\nmaking the topological phase more robust. Increasing the disorder further\neventually leads to a change of trend and to a phase transition to a trivial\nphase. Interestingly the transition occurs at $\\xi_0\\gg l$, where $l$ is the\ndisorder mean-free path and $\\xi_0$ is the localization length in the clean\nlimit. Our results are particularly relevant to a 1D topological\nsuperconductors formed in planar Josephson junctions.",
        "positive": "Vibration-assisted exciton transfer in molecular aggregates strongly\n  coupled to confined light fields: We investigate exciton transport through one-dimensional molecular aggregates\ninteracting strongly with a cavity mode. Unlike several prior theoretical\nstudies treating the monomers as simple two-level systems, exciton-vibration\ncoupling is explicitly included in the description of open quantum dynamics of\nthe system. In the framework of the Holstein-Tavis-Cummings model with\ntruncated vibrational space, we investigate the steady-state exciton transfer\nthrough both a molecular dimer and longer molecular chains. For a molecular\ndimer, we find that vibration-assisted exciton transfer occurs at strong\nexciton-cavity coupling regime where the vacuum Rabi splitting matches the\nfrequency of a single vibrational quanta. Whereas for longer molecule chains,\nvibration-assisted transfer is found to occur at the ultrastrong exciton-cavity\ncoupling limit. In addition, finite relaxation of vibrational modes induced by\nthe continuous phonon bath is found to further facilitate the exciton transport\nin vibrational enhancement regimes."
    },
    {
        "anchor": "Brillouin-Wigner theory for high-frequency expansion in periodically\n  driven systems: Application to Floquet topological insulators: We construct a systematic high-frequency expansion for periodically driven\nquantum systems based on the Brillouin-Wigner (BW) perturbation theory, which\ngenerates an effective Hamiltonian on the projected zero-photon subspace in the\nFloquet theory, reproducing the quasienergies and eigenstates of the original\nFloquet Hamiltonian up to desired order in $1/\\omega$, with $\\omega$ being the\nfrequency of the drive. The advantage of the BW method is that it is not only\nefficient in deriving higher-order terms, but even enables us to write down the\nwhole infinite series expansion, as compared to the van Vleck degenerate\nperturbation theory. The expansion is also free from a spurious dependence on\nthe driving phase, which has been an obstacle in the Floquet-Magnus expansion.\nWe apply the BW expansion to various models of noninteracting electrons driven\nby circularly polarized light. As the amplitude of the light is increased, the\nsystem undergoes a series of Floquet topological-to-topological phase\ntransitions, whose phase boundary in the high-frequency regime is well\nexplained by the BW expansion. As the frequency is lowered, the high-frequency\nexpansion breaks down at some point due to band touching with nonzero-photon\nsectors, where we find numerically even more intricate and richer Floquet\ntopological phases spring out. We have then analyzed, with the Floquet\ndynamical mean-field theory, the effects of electron-electron interaction and\nenergy dissipation. We have specifically revealed that phase transitions from\nFloquet-topological to Mott insulators emerge, where the phase boundaries can\nagain be captured with the high-frequency expansion.",
        "positive": "A topological principle for photovoltaics: Shift current in\n  intrinsically polar insulators: To realize an efficient solar cell without inhomogeneous doping, one would\nlike to maximize the shift component of the bulk photovoltaic current, in\nnoncentric semiconductors with wide band gaps. I achieve this maximization for\na new class of topological insulators whose band topology is only compatible\nwith a polar crystal class. For such insulators, it is impossible to\ncontinuously tune the $\\boldsymbol{k}$-dependent electron-hole dipole moment\n(or `shift vector') to zero throughout the Brillouin zone. Averaging the shift\nvector over all high-symmetry cross-sections of the Brillouin zone gives\nexactly a rational multiple of a Bravais lattice vector, which points parallel\nto the polar axis. Even with wide band gaps, the frequency-integrated shift\nconductivity of intrinsically polar insulators greatly exceeds $e^3/h^2$, and\nis at least three orders of magnitude larger than the conductivity of the\nprototypical ferroelectric BaTiO$_3$, challenging a widely-held expectation\nthat small band gaps are necessary for large shift currents in topological\nmaterials. Close to a topological phase transition, the integrated conductivity\ndiverges as $|E_g|^{-1/2}$ with $E_g$ the band gap, suggesting an application\nto ultrafast infrared detection."
    },
    {
        "anchor": "Resonant Fibonacci Quantum Well Structures: We propose a resonant one-dimensional quasicrystal, namely, a multiple\nquantum well (MQW) structure satisfying the Fibonacci-chain rule with the\ngolden ratio between the long and short inter-well distances. The resonant\nBragg condition is generalized from the periodic to Fibonacci MQWs. A\ndispersion equation for exciton-polaritons is derived in the two-wave\napproximation, the effective allowed and forbidden bands are found. The\nreflection spectra from the proposed structures are calculated as a function of\nthe well number and detuning from the Bragg condition.",
        "positive": "Nonlinear quantum optical properties of graphene: the role of chirality\n  and symmetry: We present a semiclassical theory of linear and nonlinear optical response of\ngraphene. The emphasis is placed on the nonlinear optical response of graphene\nfrom the standpoint of the underlying chiral symmetry. The Bloch quasiparticles\nin low energy limit, around the degeneracy points are dominantly chiral. It is\nshown for the first time that this chiral behavior in conjunction with scale\ninvariance in graphene around the Dirac points results in the strong nonlinear\noptical response. Explicit expressions for the linear and nonlinear\nconductivity tensors are derived based on Semiconductor Bloch Equations (SBEs).\nThe linear terms agree with the result of Kubo formulation. The three main\nadditive mechanisms contribute in the nonlinear optical response of graphene:\npure intraband, pure interband and the interplay between them. For each\ncontribution, an explicit response function is derived. The Kerr-type\nnonlinearity of graphene is then studied and it is demonstrated that its Kerr\nnonlinear coefficient is several orders of magnitude higher than that of many\nother known semiconductors. In addition, the nonlinear refractive index of\ngraphene can also be tuned and enhanced by applying a gate voltage."
    },
    {
        "anchor": "Optical Control of Topological Quantum Transport in Semiconductors: Intense coherent laser radiation red-detuned from absorption edge can\nreactively activate sizable Hall type charge and spin transport in n-doped\nparamagnetic semiconductors as a consequence of k-space Berry curvature\ntransferred from valence band to photon-dressed conduction band. In the\npresence of disorder, the optically induced Hall conductance can change sign\nwith laser intensity.",
        "positive": "Kinetics of Electrodeposition of Silver and Copper at Template Synthesis\n  of Nanowires: The results of investigation of kinetics of nanopores filling into membranes\nfrom aluminum oxide (pore diameter - 200 nm, porosity ~ 50%) at\nelectrodeposition of copper and silver are described. It is shown, that at\nidentical quantity of electricity passed through solutions, the degree of pores\nfilling by metal (average thickness of a deposit) is various for copper and\nsilver deposition. Calculated (according Faraday Law) and experimental\ndependences of deposition rates of these metals on quantity of electricity\npassed at direct and pulse currents are presented. Galvanodynamic i - v\ndependences have been obtained at various current scanning rates. The smaller\nrate of deposition allows to decrease concentration limitations of electrode\nprocess and to obtain higher average thickness of metal deposits and higher\nfilling degree. The limiting values of quantity of electricity for direct and\npulse currents were determined. The average thickness of silver and copper\ndeposits was obtained. A degree of pores filling, the morphology and chemical\nmicroanalysis were studied on cross-section of the membrane, using TESCAN SEM\nequipped with an Oxford Instruments INCA Enerqy EDX-system."
    },
    {
        "anchor": "Moir\u00e9 effects in graphene--hBN heterostructures: Encapsulating graphene in hexagonal Boron Nitride has several advantages: the\nhighest mobilities reported to date are achieved in this way, and precise\nnanostructuring of graphene becomes feasible through the protective hBN layers.\nNevertheless, subtle effects may arise due to the differing lattice constants\nof graphene and hBN, and due to the twist angle between the graphene and hBN\nlattices. Here, we use a recently developed model which allows us to perform\nband structure and magnetotransport calculations of such structures, and show\nthat with a proper account of the moir\\'e physics an excellent agreement with\nexperiments can be achieved, even for complicated structures such as disordered\ngraphene, or antidot lattices on a monolayer hBN with a relative twist angle.\nCalculations of this kind are essential to a quantitative modeling of\ntwistronic devices.",
        "positive": "High Figure of Merit Magneto Optics from Interfacial Skyrmions on\n  Topological Insulators: In the Kerr rotation geometry, magneto optic memory devices typically suffer\nfrom low figure-of-merit (FOM) and long write times. We show that skyrmions\nformed at the interface of a thin-film multiferroic and a topological insulator\ncan give rise to high FOM magneto optic Kerr effects (MOKEs). Huge differential\nMOKE can arise in parts of the phase diagram. Resonance like features in the\nMOKE spectra arising from the induced low energy TI bandgap, the\nmultiferroic-film thickness, and the high energy Drude like behavior are\nresolved and explained. The Fermi level dependence of the MOKE signatures is\ndistinct for the different magnetic textures. This has broad implications for\nmagnetic texture characterization, electro-optic modulators and isolators and\nhigh density magnetic optic memory."
    },
    {
        "anchor": "Tuning the Josephson current in carbon nanotubes with the Kondo effect: We investigate the Josephson current in a single wall carbon nanotube\nconnected to superconducting electrodes. We focus on the parameter regime in\nwhich transport is dominated by Kondo physics. A sizeable supercurrent is\nobserved for odd number of electrons on the nanotube when the Kondo temperature\nTk is sufficiently large compared to the superconducting gap. On the other hand\nwhen, in the center of the Kondo ridge, Tk is slightly smaller than the\nsuperconducting gap, the supercurrent is found to be extremely sensitive to the\ngate voltage Vbg. Whereas it is largely suppressed at the center of the ridge,\nit shows a sharp increase at a finite value of Vbg. This increase can be\nattributed to a doublet-singlet transition of the spin state of the nanotube\nisland leading to a pi shift in the current phase relation. This transition is\nvery sensitive to the asymmetry of the contacts and is in good agreement with\ntheoretical predictions.",
        "positive": "Axionic Band Topology in Inversion-Symmetric Weyl-Charge-Density Waves: In recent theoretical and experimental investigations, researchers have\nlinked the low-energy field theory of a Weyl semimetal gapped with a\ncharge-density wave (CDW) to high-energy theories with axion electrodynamics.\nHowever, it remains an open question whether a lattice regularization of the\ndynamical Weyl-CDW is in fact a single-particle axion insulator (AXI). In this\nLetter, we use analytic and numerical methods to study both\nlattice-commensurate and incommensurate minimal (magnetic) Weyl-CDW phases in\nthe mean-field state. We observe that, as previously predicted from field\ntheory, the two inversion- ($\\mathcal{I}$-) symmetric Weyl-CDWs with $\\phi =\n0,\\pi$ differ by a topological axion angle $\\delta\\theta_{\\phi}=\\pi$. However,\nwe crucially discover that $neither$ of the minimal Weyl-CDW phases at\n$\\phi=0,\\pi$ is individually an AXI; they are instead quantum anomalous Hall\n(QAH) and \"obstructed\" QAH insulators that differ by a fractional translation\nin the modulated cell, analogous to the two phases of the Su-Schrieffer-Heeger\nmodel of polyacetylene. Using symmetry indicators of band topology and\nnon-abelian Berry phase, we demonstrate that our results generalize to\nmulti-band systems with only two Weyl fermions, establishing that minimal\nWeyl-CDWs unavoidably carry nontrivial Chern numbers that prevent the\nobservation of a static magnetoelectric response. We discuss the experimental\nimplications of our findings, and provide models and analysis generalizing our\nresults to nonmagnetic Weyl- and Dirac-CDWs."
    },
    {
        "anchor": "Scattering theory of the Johnson spin transistor: We discuss a simple, semiclassical scattering theory for spin-dependent\ntransport in a many-terminal formulation, with special attention to the four\nterminal device of Johnson referred to as spin transistor",
        "positive": "Comment on \"Impurity spectra of graphene under electric and magnetic\n  fields\": In a recent publication [Phys. Rev. B $\\textbf{89}$, 155403 (2014)], the\nauthors investigated the spectrum of a Coulomb impurity in graphene in the\npresence of magnetic and electric fields using the coupled series expansion\napproach. In the first part of their publication they investigated how Coulomb\nimpurity states collapse in the presence of a perpendicular magnetic field. We\nargue that the obtained spectrum does not give information about the atomic\ncollapse and that their interpretation of the spectrum regarding atomic\ncollapse is not correct. We also argue that the obtained results are only valid\nup to the dimensionless charge $\\mid \\alpha\\mid=0.5$ and in order to obtain\ncorrect results for $\\alpha>0.5$ a proper regularisation of the Coulomb\ninteraction is required. Here we present the correct numerical results for the\nspectrum for arbitrary values of $\\alpha$."
    },
    {
        "anchor": "Measurement of electron-hole friction in an n-doped GaAs/AlGaAs quantum\n  well using optical transient grating spectroscopy: We use phase-resolved transient grating spectroscopy to measure the drift and\ndiffusion of electron-hole density waves in a semiconductor quantum well. The\nunique aspects of this optical probe allow us to determine the frictional force\nbetween a two-dimensional Fermi liquid of electrons and a dilute gas of holes.\nKnowledge of electron-hole friction enables prediction of ambipolar dynamics in\nhigh-mobility electron systems.",
        "positive": "Partial spin reversal in magnetic deflagration: The reversal of spins in a magnetic material as they relax toward equilibrium\nis accompanied by the release of Zeeman energy which can lead to accelerated\nspin relaxation and the formation of a well-defined self-sustained propagating\nspin-reversal front known as magnetic deflagration. To date, studies of\nMn$_{12}$-acetate single crystals have focused mainly on deflagration in large\nlongitudinal magnetic fields and found a fully spin-reversed final state. We\nreport a systematic study of the effect of transverse magnetic field on\nmagnetic deflagration and demonstrate that in small longitudinal fields the\nfinal state consists of only partially reversed spins. Further, we measured the\nfront speed as a function of applied magnetic field. The theory of magnetic\ndeflagration, together with a modification that takes into account the partial\nspin reversal, fits the transverse field dependence of the front speed but not\nits dependence on longitudinal field. The most significant result of this study\nis the finding of a partially spin-reversed final state, which is evidence that\nthe spins at the deflagration front are also only partially reversed."
    },
    {
        "anchor": "Magnetotransport in a double quantum wire: Modeling using a scattering\n  formalism built on the Lippmann-Schwinger equation: We model electronic transport through a double quantum wire in an external\nhomogeneous perpendicular magnetic field using a scattering formalism built on\nthe Lippmann-Schwinger equation. In the scattering region a window is opened\nbetween the parallel wires allowing for inter- and intra-wire scattering\nprocesses. Due to the parity breaking of the magnetic field the ensuing subband\nenergy spectrum of the double wire system with its regimes of hole- and\nelectron-like propagating modes leads to a more structure rich conductance as a\nfunction of the energy of the incoming waves than is seen in a single\nparabolically confined quantum wire. The more complex structure of the\nevanescent modes of the system also leaves its marks on the conductance.",
        "positive": "Effect of hydrostatic pressure on transport in the topological insulator\n  Bi$_2$Te$_2$Se: The Hall coefficient $R_H$ and resistivity $\\rho$ of the topological\ninsulator Bi$_2$Te$_2$Se display a number of puzzling features vs. temperature\n$T$. We propose a model that describes well the non-monotonic variation of\n$R_H(T)$. A key feature of the model is a chemical potential that is weakly\n$T$-dependent. From the fit to the model, we infer a \"transport\" gap $\\Delta_T$\nof 50 mV. We find that hydrostatic pressure $P$ (0-27 kbar) has a pronounced\neffect on both $R_H$ and $\\rho$. We show that these changes arise from\ndecreases in both $\\Delta_T$ and the hole effective mass under pressure."
    },
    {
        "anchor": "Dynamical role of anyonic excitation statistics in rapidly rotating Bose\n  gases: We show that for rotating harmonically trapped Bose gases in a fractional\nquantum Hall state, the anyonic excitation statistics in the rotating gas can\neffectively play a {\\em dynamical} role. For particular values of the\ntwo-dimensional coupling constant $g = -2\\pi \\hbar^2 (2k-1)/m$, where $k$ is a\npositive integer, the system becomes a noninteracting gas of anyons, with\nexactly obtainable solutions satisfying Bogomol'nyi self-dual order parameter\nequations. Attractive Bose gases under rapid rotation thus can be stabilized in\nthe thermodynamic limit due to the anyonic statistics of their quasiparticle\nexcitations.",
        "positive": "Vortex liquids and vortex quantum Hall states in trapped rotating Bose\n  gases: We discuss the feasibility of quantum Hall states of vortices in trapped\nlow-density two-dimensional Bose gases with large particle interactions. For\ninteraction strengths larger than a critical dimensionless 2D coupling constant\n$g_c \\approx 0.6$, upon increasing the rotation frequency, the system is shown\nto spatially separate into vortex lattice and melted vortex lattice (vortex\nliquid) phases. At a first critical frequency, the lattice melts completely,\nand strongly correlated vortex and particle quantum Hall liquids coexist in\ninner respectively outer regions of the gas cloud. Finally, at a second\ncritical frequency, the vortex liquid disappears and the strongly correlated\nparticle quantum Hall state fills the whole sample."
    },
    {
        "anchor": "Exciton-plasmaritons in graphene-semiconductor structures: We study strong coupling between plasmons in monolayer charge-doped graphene\nand excitons in a narrow gap semiconductor quantum well separated from graphene\nby a potential barrier. We show that the Coulomb interaction between excitons\nand plasmons result in mixed states described by a Hamiltonian similar to that\nfor exciton-polaritons and derive the exciton-plasmon coupling constant that\ndepends on system parameters. We calculate numerically the Rabi splitting of\nexciton- plasmariton dispersion branches for several semiconductor materials\nand find that it can reach values of up to 50 - 100 meV.",
        "positive": "Plasma Excitations in Graphene: Their Spectral Intensity and Temperature\n  Dependence in Magnetic Field: In this paper, we calculated the dielectric function, the loss function, the\nmagnetoplasmon dispersion relation and the temperature-induced transitions for\ngraphene in a uniform perpendicular magnetic field B. The calculations were\nperformed using the Peierls tight-binding model to obtain the energy band\nstructure and the random-phase approximation to determine the collective plasma\nexcitation spectrum. The single-particle and collective excitations have been\nprecisely identified based on the resonant peaks in the loss function. The\ncritical wave vector at which plasmon damping takes place is clearly\nestablished. This critical wave vector depends on the magnetic field strength\nas well as the levels between which the transition takes place. The temperature\neffects were also investigated. At finite temperature, there are plasma\nresonances induced by the Fermi distribution function. Whether such plasmons\nexist is mainly determined by the field strength, temperature, and momentum.\nThe inelastic light scattering spectroscopies could be used to verify the\nmagnetic field and temperature induced plasmons."
    },
    {
        "anchor": "Nonlinear Effects in Multi-Photon Polaritonics: We consider theoretically nonlinear effects in a semiconductor quantum well\nembedded inside a photonic microcavity. Two-photon absorption by a 2p exciton\nstate is considered and investigated; the matrix element of two-photon\nabsorption is calculated. We compute the emission spectrum of the sample and\ndemonstrate that under coherent pumping the nonlinearity of the two photon\nabsorption process gives rise to bistability.",
        "positive": "Computational study of microwave oscillations in absence of external\n  field in nonstandard spin valves in the diffusive transport limit: An anomalous (inverse) spin accumulation in the nonmagnetic spacer may build\nup when the spin valve consists of magnetic films having different spin\nsymmetries. This leads to wavy-like dependence of spin-transfer torque on the\nangle between magnetizations, as predicted by spin-dependent diffusive\ntransport model, and also confirmed experimentally. Making use of these\npredictions, we have numerically studied the magnetization dynamics in presence\nof such a wavy-torque in Co(8 nm)/Cu(10 nm)/Py(8 nm) nanopillar, considering\ngeometry with extended and etched Co layer. In both cases we specify conditions\nfor the out-of-plane precession to appear in absence of external magnetic field\nand neglecting thermal fluctuations. We prove the assumption of wavy-like\ntorque angular dependence to be fully consistent with experimental\nobservations. We also show that some features reported experimentally, like\nnonlinear slope of frequency vs. current behavior, are beyond the applicability\nrange of macrospin approximation and can be explained only by means of full\nmicromagnetic analysis."
    },
    {
        "anchor": "Dephasing and Hyperfine Interaction in Carbon Nanotubes Double Quantum\n  Dots: Disordered Case: We study theoretically the \\emph{return probability experiment}, used to\nmeasure the dephasing time $T_2^*$, in a double quantum dot (DQD) in\nsemiconducting carbon nanotubes (CNTs) with spin-orbit coupling and disorder\ninduced valley mixing. Dephasing is due to hyperfine interaction with the spins\nof the ${}^{13}$C nuclei. Due to the valley and spin degrees of freedom four\nbounded states exist for any given longitudinal mode in the quantum dot. At\nzero magnetic field the spin-orbit coupling and the valley mixing split those\nfour states into two Kramers doublets. The valley mixing term for a given dot\nis determined by the intra-dot disorder and therefore the states in the Kramers\ndoublets belonging to different dots are different. We show how nonzero\nsingle-particle interdot tunneling amplitudes between states belonging to\ndifferent doublets give rise to new avoided crossings, as a function of\ndetuning, in the relevant two particle spectrum, crossing over from the two\nelectrons in one dot states configuration, $(0,2)$, to the one electron in each\ndot configuration, $(1,1)$. In contrast to the clean system, multiple\nLandau-Zener processes affect the separation and the joining stages of each\nsingle-shot measurement and they affect the outcome of the measurement in a way\nthat strongly depends on the initial state. We find that a well-defined return\nprobability experiment is realized when, at each single-shot cycle, the (0,2)\nground state is prepared. In this case, valley mixing increases the saturation\nvalue of the measured return probability, whereas the probability to return to\nthe (0,2) ground state remains unchanged. Finally, we study the effect of the\nvalley mixing in the high magnetic field limit; for a parallel magnetic field\nthe predictions coincide with a clean nanotube, while the disorder effect is\nalways relevant with a magnetic field perpendicular to the nanotube axis.",
        "positive": "Manipulating quantum channels in weak topological insulator\n  nanoarchitectures: In $strong$ topological insulators protected surface states are always\nmanifest, while in $weak$ topological insulators (WTI) the corresponding\nmetallic surface states are either manifest or hidden, depending on the\norientation of the surface. One can design a nanostep on the surface of WTI\nsuch that a protected helical channel appears along it. In a more generic WTI\nnanostructure, multiple sets of such quasi-1D channels emerge and are coupled\nto each other. We study the response of the electronic spectrum associated with\nsuch quasi-1D surface modes against a magnetic flux piercing the system in the\npresence of disorder, and find a non-trivial, connected spectral flow as a\nclear signature indicating the immunity of the surface modes to disorder. We\npropose that the WTI nanoarchitecture is a promising platform for realizing\ntopologically protected nanocircuits immune to disorder."
    },
    {
        "anchor": "Selective equilibration of spin and valley polarized quantum Hall edge\n  states in graphene: We report on transport measurements of dual-gated, single-layer graphene\ndevices in the quantum Hall regime, allowing for independent control of the\nfilling factors in adjoining regions. Progress in device quality allows us to\nstudy scattering between edge states when the four-fold degeneracy of the\nLandau level is lifted by electron correlations, causing edge states to be spin\nand/or valley polarized. In this new regime, we observe a dramatic departure\nfrom the equilibration seen in more disordered devices: edge states with\nopposite spins propagate without mixing. As a result, the degree of\nequilibration inferred from transport can reveal the spin polarization of the\nground state at each filling factor. In particular, the first Landau level is\nshown to be spin-polarized at half-filling, providing an independent\nconfirmation of a conclusion of Ref.[1]. The conductance in the bipolar regime\nis strongly suppressed, indicating that co-propagating edge states, even with\nthe same spin, do not equilibrate along PN interfaces. We attribute this\nbehavior to the formation of an insulating nu=0 stripe at the PN interface.",
        "positive": "Phase Transitions in Dissipative Quantum Transport and Mesoscopic\n  Nuclear Spin Pumping: Topological phase transitions can occur in the dissipative dynamics of a\nquantum system when the ratio of matrix elements for competing transport\nchannels is varied. Here we establish a relation between such behavior in a\nclass of non-Hermitian quantum walk problems [M. S. Rudner and L. S. Levitov,\nPhys. Rev. Lett. 102, 065703 (2009)] and nuclear spin pumping in double quantum\ndots, which is mediated by the decay of a spin-blockaded electron triplet state\nin the presence of spin-orbit and hyperfine interactions. The transition occurs\nwhen the strength of spin-orbit coupling exceeds the strength of the net\nhyperfine coupling, and results in the complete suppression of nuclear spin\npumping. Below the transition point, nuclear pumping is accompanied by a strong\nreduction in current due to the presence of non-decaying \"dark states\" in this\nregime. Due to its topological character, the transition is expected to be\nrobust against dephasing of the electronic degrees of freedom."
    },
    {
        "anchor": "Dynamics of a single-atom electron pump: Single-electron pumps based on isolated impurity atoms have recently been\nexperimentally demonstrated. In these devices the Coulomb potential of an atom\ncreates a localised electron state with a large charging energy and\nconsiderable orbital level spacings, enabling robust charge capturing\nprocesses. In these single-atom pumps, the confinement potential is hardly\naffected by the periodic driving of the system. This is in contrast to the\noften used gate-defined quantum dot pumps, for which a strongly time-dependent\npotential leads to significantly different charge pumping processes. Here we\ndescribe the behaviour and the performance of an atomic, single parameter,\nelectron pump. This is done by considering the loading, isolating and unloading\nof one electron at the time, on a phosphorous atom embedded in a silicon double\ngate transistor. The most important feature of the atom pump is its very\nisolated ground state, which can be populated through the fast loading of much\nhigher lying excited states and a subsequent fast relaxation proces. This leads\nto a substantial increase in pumping accuracy, and is opposed to the adverse\nrole of excited states as observed for quantum dot pumps due to non-adiabatic\nexcitations. The pumping performances are investigated as a function of dopant\nposition, revealing a pumping behaviour robust against the expected variability\nin atomic position.",
        "positive": "Field effect doping of graphene in metal|dielectric|graphene\n  heterostructures: a model based upon first-principles calculations: We study how the Fermi energy of a graphene monolayer separated from a\nconducting substrate by a dielectric spacer depends on the properties of the\nsubstrate and on an applied voltage. An analytical model is developed that\ndescribes the Fermi level shift as a function of the gate voltage, of the\nsubstrate work function, and of the type and thickness of the dielectric\nspacer. The parameters of this model, that should describe the effect of gate\nelectrodes in field-effect devices, can be obtained from density functional\ntheory (DFT) calculations on single layers or interfaces. The doping of\ngraphene in metal|dielectric|graphene structures is found to be determined not\nonly by the difference in work function between the metal and graphene and the\ndielectric properties of the spacer but potential steps that result from\ndetails of the microscopic bonding at the interfaces also play an important\nrole. The doping levels predicted by the model agree very well with the results\nobtained from first-principles DFT calculations on metal|dielectric|graphene\nstructures with the metals Al, Co, Ni, Cu, Pd, Ag, Pt or Au, and a h-BN or\nvacuum dielectric spacer."
    },
    {
        "anchor": "Crossover between trivial zero modes in Majorana nanowires: We consider the superconductor-semiconductor nanowire hybrid Majorana\nplatform (\"Majorana nanowire\") in the presence of a deterministic spatially\nslowly varying inhomogeneous chemical potential and a random spatial quenched\npotential disorder, both of which are known to produce nontopological\nalmost-zero-energy modes mimicking the theoretically predicted topological\nMajorana zero modes. We study the crossover among these mechanisms by\ncalculating the tunnel conductance while varying the relative strength between\ninhomogeneous potential and random disorder in a controlled manner. We find\nthat the entire crossover region manifests abundant trivial zero modes, many of\nwhich showing the apparent \"quantization\" of the zero-bias conductance peak at\n$ 2e^2/h $, with occasional disorder-dominated peaks exceeding $ 2e^2/h $. We\npresent animations of the simulated crossover behavior and discuss experimental\nimplications. Additionally, in order to simulate the realistic disorder in\nexperimental nanowires, we also study in depth the case of disorder arising\nfrom random individual static impurities along the wire, and consider crossover\nassociated with such impurity effects. Our results, when compared qualitatively\nwith existing Majorana nanowire experimental results, indicate the dominant\nrole of random disorder in the experiments. It turns out that all three\nmechanisms may produce trivial zero-bias peaks in the tunnel conductance, and\nthe crossover among these physical mechanisms (i.e., when more than one\nmechanism is present in the system) is smooth and continuous, making it\ndifficult a priori to conclude which mechanism is dominant in a particular\nsample just by a casual inspection of the zero-bias conductance peaks.",
        "positive": "Magnetic field stabilized Wigner crystal states in a graphene moir\u00e9\n  superlattice: Wigner crystals are predicted as the crystallization of the dilute electron\ngas moving in a uniform background when the electron-electron Coulomb energy\ndominates the kinetic energy. The Wigner crystal has previously been observed\nin the ultraclean two-dimensional electron gas (2DEG) present on the surface of\nliquid helium and in semiconductor quantum wells at high magnetic field. More\nrecently, Wigner crystals have also been reported in WS2/WSe2 moir\\'e\nheterostructures. ABC-stacked trilayer graphene on boron nitride (ABC-TLG/hBN)\nmoir\\'e superlattices provide a unique tunable platform to explore Wigner\ncrystal states where the electron correlation can be controlled by electric and\nmagnetic field. Here we report the observation of magnetic field stabilized\nWigner crystal states in a ABC-TLG/hBN moir\\'e superlattice. We show that\ncorrelated insulating states emerge at multiple fractional and integer fillings\ncorresponding to v = 1/3, 2/3, 1, 4/3, 5/3 and 2 electrons per moir\\'e lattice\nsite under a magnetic field. These correlated insulating states can be\nattributed to generalized Mott states for the integer fillings (v = 1, 2) and\ngeneralized Wigner crystal states for the fractional fillings (v = 1/3, 2/3,\n4/3, 5/3). The generalized Wigner crystal states are stabilized by a vertical\nmagnetic field, and they are strongest at one magnetic flux quantum per three\nmoir\\'e superlattices. The correlated insulating states at v = 2 persists up to\n30 Tesla, which can be described by a Mott-Hofstadter transition at high\nmagnetic field. The tunable Mott and Wigner crystal states in the ABC-TLG/hBN\nhighlight the opportunities to discover new correlated quantum phases due to\nthe interplay between the magnetic field and moir\\'e flatbands."
    },
    {
        "anchor": "Emergence of Interlayer Coherence in Twist-Controlled Graphene Double\n  Layers: We report enhanced interlayer tunneling with reduced linewidth at zero\ninterlayer bias in a twist-controlled double monolayer graphene heterostructure\nin the quantum Hall regime, when the top ($\\nu_{\\mathrm{T}}$) and bottom\n($\\nu_{\\mathrm{B}}$) layer filling factors are near $\\nu_{\\mathrm{T}}=\\pm1/2,\n\\pm3/2$ and $\\nu_{\\mathrm{B}}=\\pm1/2, \\pm3/2$, and the total filling factor\n$\\nu = \\pm1$ or $\\pm3$. The zero-bias interlayer conductance peaks are stable\nagainst variations of layer filling factor, and signal the emergence of\ninterlayer phase coherence. Our results highlight twist control as a key\nattribute in revealing interlayer coherence using tunneling.",
        "positive": "Creating Majorana modes from segmented Fermi surface: We present a new platform for creating Majorana bound states from 2D gapless\nsuperconducting state in spin-helical systems under the in-plane Zeeman field.\nTopological 1D channels are formed by quantum confinement of quasiparticles via\nAndreev reflection from the surrounding fully gapped superconducting region.\nOur proposal can be realized using narrow strips of magnetic insulators on top\nof proximitized 3D topological insulators. This setup has key advantages that\ninclude: small Zeeman fields, no required fine-tuning of chemical potential,\nremoval of the low-energy detrimental states, and large attainable topological\ngap."
    },
    {
        "anchor": "Probing a spin-glass state in SrRuO3 thin films through higher-order\n  statistics of resistance fluctuations: The complex perovskite oxide SrRuO3 shows intriguing transport properties at\nlow temperatures due to the interplay of spin, charge, and orbital degrees of\nfreedom. One of the open questions in this system is regarding the origin and\nnature of the low-temperature glassy state. In this paper we report on\nmeasurements of higher-order statistics of resistance fluctuations performed in\nepitaxial thin films of SrRuO3 to probe this issue. We observe large\nlow-frequency non-Gaussian resistance fluctuations over a certain temperature\nrange. Our observations are compatible with that of a spin-glass system with\nproperties described by hierarchical dynamics rather than with that of a simple\nferromagnet with a large coercivity.",
        "positive": "Landau damping of surface plasmons in metal nanostructures: We develop a quantum-mechanical theory for Landau damping of surface plasmons\nin metal nanostructures larger that the characteristic length for nonlocal\neffects. We show that the electron surface scattering, which facilitates\nplasmon decay in small nanostructures, can be incorporated into the metal\ndielectric function on par with phonon and impurity scattering. The derived\nsurface scattering rate is determined by the plasmon local field polarization\nrelative to the metal-dielectric interface and is highly sensitive to the\nsystem geometry. We illustrate our model by providing analytical results for\nsurface scattering rate in some common shape nanostructures."
    },
    {
        "anchor": "Observation of out-of-plane spin texture in a SrTiO3 (111)\n  two-dimensional electron gas: We explore the second order bilinear magnetoelectric resistance (BMER) effect\nin the d-electron-based two-dimensional electron gas (2DEG) at the SrTiO3 (111)\nsurface. We find an evidence of a spin-split band structure with the archetypal\nspin-momentum locking of the Rashba effect for the in-plane component. Under an\nout-of-plane magnetic field, we find a BMER signal that breaks the six-fold\nsymmetry of the electronic dispersion, which is a fingerprint for the presence\nof a momentum dependent out-of-plane spin component. Relativistic electronic\nstructure calculations reproduce this spin-texture and indicate that the\nout-of-plane component is a ubiquitous property of oxide 2DEGs arising from\nstrong crystal field effects. We further show that the BMER response of the\nSrTiO3 (111) 2DEG is tunable and unexpectedly large.",
        "positive": "Level attraction in a microwave optomechanical circuit: Level repulsion - the opening of a gap between two degenerate modes due to\ncoupling - is ubiquitous anywhere from solid state theory to quantum chemistry.\nIn contrast, if one mode has negative energy, the mode frequencies attract\ninstead. They converge and develop imaginary components, leading to an\ninstability; an exceptional point marks the transition. This, however, only\noccurs if the dissipation rates of the two modes are comparable. Here we expose\na theoretical framework for the general phenomenon and realize it\nexperimentally through engineered dissipation in a multimode superconducting\nmicrowave optomechanical circuit. Level attraction is observed for a mechanical\noscillator and a superconducting microwave cavity, while an auxiliary cavity is\nused for sideband cooling. Two exceptional points are demonstrated that could\nbe exploited for their topological properties."
    },
    {
        "anchor": "Magnetization reversal assisted by half antivortex states in\n  nanostructured circular cobalt disks: The half antivortex, a fundamental topological structure which determines\nmagnetization reversal of submicron magnetic devices with domain walls, has\nbeen suggested also to play a crucial role in spin torque induced vortex core\nreversal in circular disks. Here we report on magnetization reversal in\ncircular disks with nanoholes through consecutive metastable states with half\nantivortices. In-plane anisotropic magnetoresistance and broadband\nsusceptibility measurements accompanied by micromagnetic simulations reveal\nthat cobalt disks with two and three linearly arranged nanoholes directed at 45\nand 135 degrees with respect to the external magnetic field show reproducible\nstep-like changes in the anisotropic magnetoresistance and magnetic\npermeability due to transitions between different intermediate states mediated\nby vortices and half antivortices confined to the dot nanoholes and edges,\nrespectively. Our findings are relevant for the development of multi-hole based\nspintronic and magnetic memory devices.",
        "positive": "Topological defects in antiferromagnetically coupled multilayers with\n  perpendicular anisotropy: A rich variety of specific multidomain textures recently observed in\nantiferromagnetically coupled multilayers with perpendicular anisotropy include\nregular (equilibrium) multidomain states as well as different types of\ntopological magnetic defects. Within a phenomenological theory we have\nclassified and analyzed the possible magnetic defects in the antiferromagnetic\nground state and determine their structures. We have derived the optimal sizes\nof the defects as functions of the antiferromagnetic exchange, the applied\nmagnetic field, and geometrical parameters of the multilayer. The calculated\nmagnetic phase diagrams show the existence regions for all types of magnetic\ndefects. Experimental investigations of the remanent states (observed after\ndifferent magnetic pre-history) in [Co/Pt]/Ru multilayers with wedged Co layers\nreveal a corresponding succession of different magnetic defect domain types."
    },
    {
        "anchor": "Formation of Plasmon-Polariton Pulses in the Cooperative Decay of\n  Excitons of Quantum Dots Near a Metal Surface: The formation of pulses of surface electromagnetic waves in a\nmetal/dielectric interface is considered in the process of cooperative decay of\nexcitons of quantum dots distributed near a metal surface in a dielectric\nlayer. It is shown that the efficiency of exciton energy transfer to excited\nplasmons can be increased by selecting the dielectric material with specified\nvalues of the complex permittivity. It is found that in the mean field\napproximation the semiclassical model of formation of plasmon pulses in the\nsystem under study is reduced to the pendulum equation with the additional term\nof nonlinear losses.",
        "positive": "Theory of spin and lattice wave dynamics excited by focused laser pulses: We develop a theory of the spin wave dynamics excited by ultrafast focused\nlaser pulses in a magnetic film. We take into account both volume and surface\nspin wave modes in the presence of applied, dipolar and magnetic anisotropy\nfields and include the dependence on laser spot exposure size and magnetic\ndamping. We show that the sound waves generated by local heating by an\nultrafast focused laser pulse can excite a wide spectrum of spin waves (on top\nof a dominant magnon-phonon contribution). Good agreement with recent\nexperiments supports the validity of the model."
    },
    {
        "anchor": "Imaging snake orbits at graphene n-p junctions: We consider conductance mapping of the snake-orbits confined along the n-p\njunction defined in graphene by the electrostatic doping in the quantum Hall\nregime. We explain the periodicity of conductance oscillations at the magnetic\nfield and the Fermi energy scales by the properties of the n-p junction as a\nconducting channel. We evaluate the conductance maps for a floating gate\nscanning the surface of the device. In the quantum Hall conditions the currents\nflow near the edges of the sample and along the n-p junction. The conductance\nmapping resolves only the n-p junction and not the edges. The conductance\noscillations along the junction are found in the maps with periodicity related\nto the cyclotron orbits of the scattering current. Stronger probe potentials\nprovide support to localized resonances at one of the sides of the junction\nwith current loops that interfere with the n-p junction currents. The\ninterference results in a series of narrow lines parallel to the junction with\npositions that strongly depend on the magnetic field through the Aharonov-Bohm\neffect. The consequences of a limited transparency of finite width n-p\njunctions are also discussed.",
        "positive": "p-i-n Tunnel FETs vs. n-i-n MOSFETs: Performance Comparison from Devices\n  to Circuits: The band-to-band tunneling transistors have some performance advantages over\nthe conventional MOSFETs due to the <60mV/dec sub-threshold slope. In this\npaper, carbon nanotubes are used as a model channel material to address issues\nthat we believe will apply to BTBT FETs vs. MOSFETs more generally. We use\npz-orbital tight-binding Hamiltonian and the non-equilibrium Green function\n(NEGF) formalism for rigorous treatment of dissipative quantum transport. A\ndevice level comparison of p-i-n TFETs and n-i-n MOSFETs in both ballistic and\ndissipative cases has been performed previously. In this paper, the possibility\nof using p-i-n TFETs in ultra-low power sub-threshold logic circuits is\ninvestigated using a rigorous numerical simulator. The results show that, in\nsub-threshold circuit operation, the p-i-n TFETs have better DC\ncharacteristics, and can deliver ~15x higher performance at the iso-P_LEAKAGE,\niso-VDD conditions. Because p-i-n TFETs can operate at lower VDD than n-i-n\nMOSFETs, they can deliver ~3x higher performance at the same power\n(P_OPERATION). This results in ~3x energy reduction under iso-delay conditions.\nTherefore the p-i-n TFETs are more suitable for sub-threshold logic operation."
    },
    {
        "anchor": "Nonlocal effects in singular plasmonic metasurfaces: A local model of the dielectric response of a metal predicts that singular\nsurfaces, such as sharp-edged structures, have a continuous absorption spectrum\nand extreme concentration of energy at the singularity. Here we show that\nnonlocality drastically alters this picture: the spectrum is now discrete and\nenergy concentration, though still substantial, is greatly reduced.",
        "positive": "Four-Step Evolution of Spin-Hall Conductance: Tight-Binding Electrons\n  with Rashba Coupling in a Magnetic Field: An intriguing magneto-transport property is demonstrated by tight-binding\nlattice electrons with Rashba spin-orbit coupling (SOC) in a magnetic field.\nWith the flux strength $\\phi={2\\pi/N}$ ($N$ is an integer) and the Zeeman\nsplitting fixed, when increasing the Rashba SOC $\\lambda$, the spin-Hall and\ncharge-Hall conductances (SHC and CHC) undergo four-step evolutions: the SHC\nshows size-dependent resonances and jumps at three critical $\\lambda_{c}$'s,\nand changes its sign at $\\lambda_{c1}$ and $\\lambda_{c3}$; while the CHC\nexhibits three quantum jumps by $-Ne^2/h$, $+2Ne^2/h$ and $-Ne^2/h$. Such\nfour-step evolutions are also reflected in topological characters and spin\npolarizations of edge states of a cylindrical system, and are robust against\nweak disorder."
    },
    {
        "anchor": "Chiral Symmetry Breaking and the Quantum Hall Effect in Monolayer\n  Graphene: Monolayer graphene in a strong magnetic field exhibits quantum Hall states at\nfilling fractions $\\nu = 0$ and $\\nu = \\pm 1$ that are not explained within a\npicture of noninteracting electrons. We propose that these states arise from\ninteraction-induced chiral symmetry-breaking orders. We argue that when the\nchemical potential is at the Dirac point, weak on-site repulsion supports an\neasy-plane antiferromagnet state, which simultaneously gives rise to\nferromagnetism oriented parallel to the magnetic field direction, whereas for\n$|\\nu|=1$ easy-axis antiferromagnet and charge-density-wave orders coexist. We\nperform self-consistent calculations of the magnetic field dependence of the\nactivation gap for the $\\nu = 0$ and $|\\nu| = 1$ states and obtain excellent\nagreement with recent experimental results. Implications of our study for\nfractional Hall states in monolayer graphene are highlighted.",
        "positive": "Topological insulators and semimetals in classical magnetic systems: Pursuing topological phases in natural and artificial materials is one of the\ncentral topics in modern physical science and engineering. In classical\nmagnetic systems, spin waves (or magnons) and magnetic solitons (such as domain\nwall, vortex, skyrmion, etc) represent two important excitations. Recently, the\ntopological insulator and semimetal states in magnon- and soliton-based\ncrystals (or metamaterials) have attracted growing attention owing to their\ninteresting dynamics and promising applications for designing robust spintronic\ndevices. Here, we give an overview of current progress of topological phases in\nstructured classical magnetism. We first provide a brief introduction to spin\nwave, and discuss its topological properties including magnon Hall effects,\ntopological magnon insulators, and Dirac (Weyl) magnon semimetals. Appealing\nproposal of topological magnonic devices is also highlighted. We then review\nthe collective-coordinate approach for describing the dynamics of magnetic\nsoliton lattice. Pedagogical topological models such as the\nSu-Schrieffer-Heeger model and the Haldane model and their manifestation in\nmagnetic soliton crystals are elaborated. Then we focus on the topological\nproperties of magnetic solitons, by theoretically analyzing the first-order\ntopological insulating phases in low dimensional systems and higher-order\ntopological states in breathing crystals. Finally, we discuss the experimental\nrealization and detection of the edge states in both the magnonic and solitonic\ncrystals. We remark the challenges and future prospects before concluding this\narticle."
    },
    {
        "anchor": "Current-induced spin polarization and the spin Hall effect: a\n  quasiclassical approach: The quasiclassical Green function formalism is used to describe charge and\nspin dynamics in the presence of spin-orbit coupling. We review the results\nobtained for the spin Hall effect on restricted geometries. The role of\nboundaries is discussed in the framework of spin diffusion equations.",
        "positive": "Spin superfluidity in noncollinear antiferromagnets: We explore the spin superfluid transport in exchange interaction dominated\nthree-sublattice antiferromagnets. The system in the long-wavelength regime is\ndescribed by an $SO(3)$ invariant field theory. Additional corrections from\nDzyaloshinskii-Moriya interactions or anisotropies can break the symmetry;\nhowever, the system still approximately holds a $U(1)$-rotation symmetry. Thus,\nthe power-law spatial decay signature of spin superfluidity is identified in a\nnonlocal-measurement setup where the spin injection is described by the\ngeneralized spin-mixing conductance. We suggest iron jarosites as promising\nmaterial candidates for realizing our proposal."
    },
    {
        "anchor": "Plasmonic Instabilities in Two-dimensional Electron Channels of Variable\n  Width: Understanding of fundamental physics of plasmonic instabilities is the key\nissue for the design of a new generation of compact electronic devices required\nfor numerous THz applications. Variable width plasmonic devices have emerged as\npotential candidates for such an application. The analysis of the variable\nwidth plasmonic devices presented in this paper shows that these structures\nenable both the Dyakonov-Shur instability (when the electron drift velocity\neverywhere in the device remains smaller than the plasma velocity) and the\n\"plasmonic boom\" instability that requires drift velocity exceeding the plasma\nvelocity in some of the device sections. For symmetrical structures, the\ndrifting current could be provided by an RF signal leading to RF to THz and THz\nto RF frequency conversion using the source and drain antennas and reducing\nlosses associated with ohmic contacts. We show that narrow regions protruding\nfrom the channel (\"plasmonic stubs\") could control and optimize boundary\nconditions at the contacts and/or at the interfaces between different device\nsections. These sections could be combined into plasmonic crystals yielding\nenhanced power and a better impedance matching. The mathematics of the problems\nis treated using the transmission line analogy. We show that the combination of\nthe stubs and the variable width channels is required for the instability rise\nin an optimized plasmonic crystal. Our estimates show that THz plasmonic\ncrystal oscillators could operate at room temperature.",
        "positive": "Fast gate-based readout of silicon quantum dots using Josephson\n  parametric amplification: Spins in silicon quantum devices are promising candidates for large-scale\nquantum computing. Gate-based sensing of spin qubits offers compact and\nscalable readout with high fidelity, however further improvements in\nsensitivity are required to meet the fidelity thresholds and measurement\ntimescales needed for the implementation of fast-feedback in error correction\nprotocols. Here, we combine radio-frequency gate-based sensing at 622 MHz with\na Josephson parametric amplifier (JPA), that operates in the 500-800 MHz band,\nto reduce the integration time required to read the state of a silicon double\nquantum dot formed in a nanowire transistor. Based on our achieved\nsignal-to-noise ratio (SNR), we estimate that singlet-triplet single-shot\nreadout with an average fidelity of 99.7% could be performed in 1 $\\mu$s,\nwell-below the requirements for fault-tolerant readout and 30 times faster than\nwithout the JPA. Additionally, the JPA allows operation at a lower RF power\nwhile maintaining identical SNR. We determine a noise temperature of 200 mK\nwith a contribution from the JPA (25%), cryogenic amplifier (25%) and the\nresonator (50%), showing routes to further increase the read-out speed."
    },
    {
        "anchor": "Magneto-optical Kerr Effect Studies of Square Artificial Spin Ice: We report a magneto-optical Kerr effect study of the collective magnetic\nresponse of artificial square spin ice, a lithographically-defined array of\nsingle-domain ferromagnetic islands. We find that the anisotropic inter-island\ninteractions lead to a non-monotonic angular dependence of the array coercive\nfield. Comparisons with micromagnetic simulations indicate that the two\nperpendicular sublattices exhibit distinct responses to island edge roughness,\nwhich clearly influence the magnetization reversal process. Furthermore, such\ncomparisons demonstrate that disorder associated with roughness in the island\nedges plays a hitherto unrecognized but essential role in the collective\nbehavior of these systems.",
        "positive": "Effect of Microwaves on the Current-Phase-Relation in SNS Josephson\n  Junctions: We investigate the current-phase-relation (CPR) of long diffusive\nsuperconductor-normal metal-superconductor (SNS) Josephson junctions in\nthermodynamic equilibrium and under microwave irradiation. While in equilibrium\ngood agreement with the predictions of quasi-classical theory is found, we\nobserve that the shape of the CPR can be strongly affected by microwave\nirradiation. Close to a Josephson-phase difference of pi, the supercurrent can\nbe strongly suppressed when increasing the rf-power. Our results can be\nunderstood in terms of microwave excitation of low-lying Andreev bound states\nacross the mini-gap in the junction. In the frequency interval studied, this\nmechanism becomes important when the mini-gap closes at a phase difference of\npi."
    },
    {
        "anchor": "Harnessing excitons at the nanoscale -- photoelectrical platform for\n  quantitative sensing and imaging: Excitons -- quasiparticles formed by the binding of an electron and a hole\nthrough electrostatic attraction -- hold promise in the fields of quantum light\nconfinement and optoelectronic sensing. Atomically thin transition metal\ndichalcogenides (TMDs) provide a versatile platform for hosting and\nmanipulating excitons, given their robust Coulomb interactions and exceptional\nsensitivity to dielectric environments. In this study, we introduce a cryogenic\nscanning probe photoelectrical sensing platform, termed exciton-resonant\nmicrowave impedance microscopy (ER-MIM). ER-MIM enables ultra-sensitive probing\nof exciton polarons and their Rydberg states at the nanoscale. Utilizing this\ntechnique, we explore the interplay between excitons and material properties,\nincluding carrier density, in-plane electric field, and dielectric screening.\nFurthermore, we employ deep learning for automated data analysis and\nquantitative extraction of electrical information, unveiling the potential of\nexciton-assisted nano-electrometry. Our findings establish an invaluable\nsensing platform and readout mechanism, advancing our understanding of exciton\nexcitations and their applications in the quantum realm.",
        "positive": "On calculation of RKKY range function in one dimension: The effect of strong singularity in the calculation of range function for the\nRKKY interaction in 1D electron gas is discussed. The method of handling this\nsingularity is presented. A possible way of avoiding the singularity in the\nRuderman-Kittel perturbation theory in 1D is described."
    },
    {
        "anchor": "Transient currents in a molecular photo-diode: Light-induced charge transmission through a molecular junction (molecular\ndiode) is studied in the framework of a HOMO-LUMO model and in using a kinetic\ndescription. Expressions are presented for the sequential (hopping) and direct\n(tunneling) transient current components together with kinetic equations\ngoverning the time-dependent populations of the neutral and charged molecular\nstates which participate in the current formation. Resonant and off-resonant\ncharge transmission processes are analyzed in detail. It is demonstrated that\nthe transient currents are associated with a molecular charging process which\nis initiated by photo excitation of the molecule. If the coupling of the\nmolecule to the electrodes is strongly asymmetric the transient currents can\nsignificantly exceed the steady state current.",
        "positive": "Optimal control of the silicon-based donor electron spin quantum\n  computing: We demonstrate how gradient ascent pulse engineering optimal control methods\ncan be implemented on donor electron spin qubits in Si semiconductors with an\narchitecture complementary to the original Kane's proposal. We focus on the\nhigh-fidelity controlled-NOT (CNOT) gate and explicitly find its digitized\ncontrol sequences by optimizing its fidelity over the external controls of the\nhyperfine A and exchange J interactions. This high-fidelity CNOT gate has an\nerror of about $10^{-6}$, below the error threshold required for fault-tolerant\nquantum computation, and its operation time of 100ns is about 3 times faster\nthan 297ns of the proposed global control scheme. It also relaxes significantly\nthe stringent distance constraint of two neighboring donor atoms of 10~20nm as\nreported in the original Kane's proposal to about 30nm in which surface A and J\ngates may be built with current fabrication technology. The effects of the\ncontrol voltage fluctuations, the dipole-dipole interaction and the electron\nspin decoherence on the CNOT gate fidelity are also discussed."
    },
    {
        "anchor": "Chaos and rectification of electromagnetic wave in a lateral\n  semiconductor superlattice: We find the conditions for a rectification of electromagnetic wave in a\nlateral semiconductor superlattice with a high mobility of electrons. The\nrectification is assisted by a transition to a dissipative chaos at a very high\nmobility. We show that mechanism responsible for the rectification is a\ncreation of warm electrons in the superlattice miniband caused by an interplay\nof the effects of nonlinearity and finite band width.",
        "positive": "Advanced Concepts in Josephson Junction Reflection Amplifiers: Low-noise amplification atmicrowave frequencies has become increasingly\nimportant for the research related to superconducting qubits and\nnanoelectromechanical systems. The fundamental limit of added noise by a\nphase-preserving amplifier is the standard quantum limit, often expressed as\nnoise temperature $T_{q} = \\hbar {\\omega}/2k_{B}$. Towards the goal of the\nquantum limit, we have developed an amplifier based on intrinsic negative\nresistance of a selectively damped Josephson junction. Here we present\nmeasurement results on previously proposed wide-band microwave amplification\nand discuss the challenges for improvements on the existing designs. We have\nalso studied flux-pumped metamaterial-based parametric amplifiers, whose\noperating frequency can be widely tuned by external DC-flux, and demonstrate\noperation at $2\\omega$ pumping, in contrast to the typical metamaterial\namplifiers pumped via signal lines at $\\omega$."
    },
    {
        "anchor": "Mesoscopic conductance and its fluctuations at non-zero Hall angle: We consider the bilocal conductivity tensor, the two-probe conductance and\nits fluctuations for a disordered phase-coherent two-dimensional system of\nnon-interacting electrons in the presence of a magnetic field, including\ncorrectly the edge effects. Analytical results are obtained by perturbation\ntheory in the limit $\\sigma_{xx} \\gg 1$. For mesoscopic systems the conduction\nprocess is dominated by diffusion but we show that, due to the lack of\ntime-reversal symmetry, the boundary condition for diffusion is altered at the\nreflecting edges. Instead of the usual condition, that the derivative along the\ndirection normal to the wall of the diffusing variable vanishes, the derivative\nat the Hall angle to the normal vanishes. We demonstrate the origin of this\nboundary condition from different starting points, using (i) a simplified\nChalker-Coddington network model, (ii) the standard diagrammatic perturbation\nexpansion, and (iii) the nonlinear sigma-model with the topological term, thus\nestablishing connections between the different approaches. Further boundary\neffects are found in quantum interference phenomena. We evaluate the mean\nbilocal conductivity tensor $\\sigma_{\\mu\\nu}(r,r')$, and the mean and variance\nof the conductance, to leading order in $1/\\sigma_{xx}$ and to order\n$(\\sigma_{xy}/\\sigma_{xx})^2$, and find that the variance of the conductance\nincreases with the Hall ratio. Thus the conductance fluctuations are no longer\nsimply described by the unitary universality class of the $\\sigma_{xy}=0$ case,\nbut instead there is a one-parameter family of probability distributions. In\nthe quasi-one-dimensional limit, the usual universal result for the conductance\nfluctuations of the unitary ensemble is recovered, in contrast to results of\nprevious authors. Also, a long discussion of current conservation.",
        "positive": "Magnetic resonance imaging of spin-wave transport and interference in a\n  magnetic insulator: Spin waves - the elementary excitations of magnetic materials - are prime\ncandidate signal carriers for low dissipation information processing. Being\nable to image coherent spin-wave transport is crucial for developing\ninterference-based spin-wave devices. We introduce a platform for probing\ncoherent spin waves based on magnetic resonance imaging with electron spins in\ndiamond. Focusing on a thin-film magnetic insulator, we quantify spin-wave\namplitudes, visualize the dispersion, and demonstrate time-domain measurements\nof spin-wave packets. We use our platform to study spin-wave interference,\nrevealing uni-directional, autofocused spin-wave patterns with\nfrequency-controlled numerical apertures. A theoretical analysis explains the\npatterns in terms of chiral spin-wave excitation and stray-field coupling to\nthe sensor spins. These results pave the way for probing spin waves in\natomically thin magnets, even when embedded between opaque materials."
    },
    {
        "anchor": "Valley-polarization in biased bilayer graphene using circularly\n  polarized light: Achieving a population imbalance between the two inequivalent valleys is a\ncritical first step for any valleytronic device. A valley-polarization can be\ninduced in biased bilayer graphene using circularly polarized light. In this\npaper, we present a detailed theoretical study of valley-polarization in biased\nbilayer graphene. We show that a nearly perfect valley-polarization can be\nachieved with the proper choices of external bias and pulse frequency. We find\nthat the optimal pulse frequency $\\omega$ is given by $\\hbar\\omega=2a,$ where\n$2a$ is the potential energy difference between the graphene layers. We also\nfind that the valley-polarization originates not from the Dirac points\nthemselves, but rather from a ring of states surrounding each. Intervalley\nscattering is found to greatly reduce the valley-polarization for high\nfrequency pulses. Thermal populations are found to significantly reduce the\nvalley-polarization for small biases. This work provides insight into the\norigin of valley-polarization in bilayer graphene and will aid experimentalists\nseeking to study valley-polarization in the lab.",
        "positive": "Disorder-induced mechanism for positive exchange bias fields: We propose a mechanism to explain the phenomenon of positive exchange bias on\nmagnetic bilayered systems. The mechanism is based on the formation of a domain\nwall at a disordered interface during field cooling (FC) which induces a\nsymmetry breaking of the antiferromagnet, without relying on any ad hoc\nassumption about the coupling between the ferromagnetic (FM) and\nantiferromagnetic (AFM) layers. The domain wall is a result of the disorder at\nthe interface between FM and AFM, which reduces the effective anisotropy in the\nregion. We show that the proposed mechanism explains several known experimental\nfacts within a single theoretical framework. This result is supported by Monte\nCarlo simulations on a microscopic Heisenberg model, by micromagnetic\ncalculations at zero temperature and by mean field analysis of an effective\nIsing like phenomenological model."
    },
    {
        "anchor": "Light-emitting diodes by bandstructure engineering in van der Waals\n  heterostructures: The advent of graphene and related 2D materials has recently led to a new\ntechnology: heterostructures based on these atomically thin crystals. The\nparadigm proved itself extremely versatile and led to rapid demonstration of\ntunnelling diodes with negative differential resistance, tunnelling\ntransistors5, photovoltaic devices, etc. Here we take the complexity and\nfunctionality of such van der Waals heterostructures to the next level by\nintroducing quantum wells (QWs) engineered with one atomic plane precision. We\ndescribe light emitting diodes (LEDs) made by stacking up metallic graphene,\ninsulating hexagonal boron nitride (hBN) and various semiconducting monolayers\ninto complex but carefully designed sequences. Our first devices already\nexhibit extrinsic quantum efficiency of nearly 10% and the emission can be\ntuned over a wide range of frequencies by appropriately choosing and combining\n2D semiconductors (monolayers of transition metal dichalcogenides). By\npreparing the heterostructures on elastic and transparent substrates, we show\nthat they can also provide the basis for flexible and semi-transparent\nelectronics. The range of functionalities for the demonstrated heterostructures\nis expected to grow further with increasing the number of available 2D crystals\nand improving their electronic quality.",
        "positive": "Transport properties of a quasi-1D Wigner Solid on liquid helium\n  confined in a microchannel with periodic potential: We present transport measurements in a quasi-1D system of surface electrons\non liquid helium confined in a 101-$\\mu$m long and 5-$\\mu$m wide microchannel\nwhere an electrostatic potential with periodicity of $1$-$\\mu$m along the\nchannel is introduced. In particular, we investigate the influence of such a\npotential on the nonlinear transport of quasi-1D Wigner Solid (WS) by varying\nthe amplitude of the periodic potential in a wide range. At zero and small\nvalues of amplitude, quasi-1D WS in microchannel shows expected features such\nas the Bragg-Cherenkov scattering of ripplons and reentrant melting. As the\namplitude of potential increases, the above features are strongly suppressed.\nThis behavior suggests loss of the long-range positional order in the electron\nsystem, which is reminiscent of the re-entrant melting behaviour due to the\nlateral confinement of WS in the channel."
    },
    {
        "anchor": "Many-body correlations of electrostatically trapped dipolar excitons: We study the photoluminescence (PL) of a two-dimensional liquid of oriented\ndipolar excitons in In_{x}Ga_{1-x}As coupled double quantum wells confined to a\nmicrotrap. Generating excitons outside the trap and transferring them at\nlattice temperatures down to T = 240 mK into the trap we create cold\nquasi-equilibrium bosonic ensembles of some 1000 excitons with thermal de\nBroglie wavelengths exceeding the excitonic separation. With decreasing\ntemperature and increasing density n <= 5*10^10 cm^{-2} we find an increasingly\nasymmetric PL lineshape with a sharpening blue edge and a broad red tail which\nwe interpret to reflect correlated behavior mediated by dipolar interactions.\nFrom the PL intensity I(E) below the PL maximum at E_{0} we extract at T < 5 K\na distinct power law I(E) \\sim (E_{0}-E)^-|\\alpha| with -|\\alpha|\\sim -0.8 in\nthe range E_{0}-E of 1.5-4 meV, comparable to the dipolar interaction energy.",
        "positive": "Quantized Conductance and Field-Effect Topological Quantum Transistor in\n  Silicene Nanoribbons: Silicene (a monolayer of silicon atoms) is a quantum spin-Hall insulator,\nwhich undergoes a topological phase transition into other insulators by\napplying external field such as electric field, photo-irradiation and\nantiferromagnetic order. We investigate the electronic and transport properties\nof silicene nanoribbons based on the Landauer formalism. We propose to\ndetermine topological phase transitions by measuring the density of states and\nconductance. The conductance is quantized and changes its value when the system\ntransforms into different phases. We show that a silicene nanoribbon near the\nzero energy acts as a field-effect transistor. This transistor is robust though\nit makes use of the minimum quantized conductance since the zero-energy edge\nstates are topologically protected. Our findings open a new way to future\ntopological quantum devices."
    },
    {
        "anchor": "Dielectric electron-hole liquid in monolayer heterostructures based on\n  transition metal dichalcogenides: The possibility of the appearance of a dielectric electron-hole liquid (EHL)\nin monolayers of transition metal dichalcogenides and heterostructures based on\nthem is considered. It is shown that the coherent pairing of electrons and\nholes in them leads to the formation of a dielectric EHL when the degree of\ncircular polarization of the exciting light exceeds a certain threshold value.\nBelow this value, a metallic EHL is realized. Some possible physical\nmanifestations of the transition between these two types of EHL are noted.",
        "positive": "Opportunities and limitations of transition voltage spectroscopy: a\n  theoretical analysis: In molecular charge transport, transition voltage spectroscopy (TVS) holds\nthe promise that molecular energy levels can be explored at bias voltages lower\nthan required for resonant tunneling. We investigate the theoretical basis of\nthis novel tool, using a generic model. In particular, we study the length\ndependence of the conducting frontier orbital and of the 'transition voltage'\nas a function of length. We show that this dependence is influenced by the\namount of screening of the electrons in the molecule, which determines the\nvoltage drop to be located at the contacts or across the entire molecule. We\nobserve that the transition voltage depends significantly on the length, but\nthat the ratio between the transition voltage and the conducting frontier\norbital is approximately constant only in strongly screening (conjugated)\nmolecules. Uncertainty about the screening within a molecule thus limits the\npredictive power of TVS. We furthermore argue that the relative length\nindependence of the transition voltage for non-conjugated chains is due to\nstrong localization of the frontier orbitals on the end groups ensuring binding\nof the rods to the metallic contacts. Finally, we investigate the\ncharacteristics of TVS in asymmetric molecular junctions. If a single level\ndominates the transport properties, TVS can provide a good estimate for both\nthe level position and the degree of junction asymmetry. If more levels are\ninvolved the applicability of TVS becomes limited."
    },
    {
        "anchor": "Effects of transverse geometry on the thermal conductivity of Si and Ge\n  nanowires: We explore the effects of geometry on the thermal conductivity (kappa) of\nsilicon and germanium nanowires, with lengths between 10-120 nm and diameters\nup to 5-6 nm. To this end we perform molecular dynamics simulations with the\nLAMMPS software, using Tersoff interatomic potentials. We consider nanowires\nwith polygonal cross section and we discuss the effect of the transverse\ngeometry on the thermal conductivity. We also consider tubular (hollow)\nnanowires and core/shell combinations of Si/Ge and Ge/Si, and we compare the\nheat transport of the core/shell structure with that of the separated core and\nshell components.",
        "positive": "Coulomb-mediated antibunching of an electron pair surfing on sound: Electron flying qubits are envisioned as potential information link within a\nquantum computer, but also promise -- alike photonic approaches -- a\nself-standing quantum processing unit. In contrast to its photonic counterpart,\nelectron-quantum-optics implementations are subject to Coulomb interaction,\nwhich provide a direct route to entangle the orbital or spin degree of freedom.\nHowever, the controlled interaction of flying electrons at the single particle\nlevel has not yet been established experimentally. Here we report antibunching\nof a pair of single electrons that is synchronously shuttled through a circuit\nof coupled quantum rails by means of a surface acoustic wave. The in-flight\npartitioning process exhibits a reciprocal gating effect which allows us to\nascribe the observed repulsion predominantly to Coulomb interaction. Our\nsingle-shot experiment marks an important milestone on the route to realise a\ncontrolled-phase gate for in-flight quantum manipulations."
    },
    {
        "anchor": "Strong lateral exchange coupling and current-induced switching in\n  single-layer ferrimagnetic films with patterned compensation temperature: Strong, adjustable magnetic couplings are of great importance to all devices\nbased on magnetic materials. Controlling the coupling between adjacent regions\nof a single magnetic layer, however, is challenging. In this work, we\ndemonstrate strong exchange-based coupling between arbitrarily shaped regions\nof a single ferrimagnetic layer. This is achieved by spatially patterning the\ncompensation temperature of the ferrimagnet by either oxidation or He+\nirradiation. The coupling originates at the lateral interface between regions\nwith different compensation temperature and scales inversely with their width.\nWe show that this coupling generates large lateral exchange coupling fields and\nwe demonstrate its application to control the switching of magnetically\ncompensated dots with an electric current.",
        "positive": "Anisotropic spin motive force in multi-layered Dirac fermion system,\n  $\u03b1$-(BEDT-TTF)$_2$I$_3$: We investigate the anisotropic spin motive force in\n$\\alpha$-(BEDT-TTF)$_2$I$_3$, which is a multi-layered massless Dirac fermion\nsystem under pressure. Assuming the interlayer antiferromagnetic interaction\nand the interlayer anisotropic ferromagnetic interaction, we numerically\nexamine the spin ordered state of the ground state using the steepest descent\nmethod. The anisotropic interaction leads to the anisotropic spin ordered\nstate. We calculate the spin motive force produced by the anisotropic spin\ntexture. The result quantitatively agrees with the experiment."
    },
    {
        "anchor": "Quantum dynamics of a nanomagnet in a rotating field: Quantum dynamics of a two-state spin system in a rotating magnetic field has\nbeen studied. Analytical and numerical results for the transition probability\nhave been obtained along the lines of the Landau-Zener-Stueckelberg theory. The\neffect of various kinds of noise on the evolution of the system has been\nanalyzed.",
        "positive": "Nonexponential photoluminescence dynamics in an inhomogeneous ensemble\n  of excitons in WSe$_2$ monolayers: The spectral and spatiotemporal dynamics of photoluminescence in monolayers\nof transition metal dichalcogenide WSe$_2$ obtained by mechanical exfoliation\non a Si/SiO$_2$ substrate is studied over a wide range of temperatures and\nexcitation powers. It is shown that the dynamics is nonexponential and, for\ntimes $t$ exceeding $\\sim$50 ps after the excitation pulse, is described by a\ndependence of the form $1/(t+t_0)$. Photoluminescence decay is accelerated with\na decrease in temperature, as well as with a decrease in the energy of emitting\nstates. It is shown that the observed dynamics cannot be described by a\nbimolecular recombination process, such as exciton--exciton annihilation. A\nmodel that describes the nonexponential photoluminescence dynamics by taking\ninto account the spread of radiative recombination times of localized exciton\nstates in a random potential gives good agreement with experimental data."
    },
    {
        "anchor": "Mean-field results on the Anderson impurity model out of equilibrium: We investigate the mean-field phase diagram of the Anderson impurity model\nout of equilibrium. Generalising the unrestricted Hartree-Fock approach to the\nnon-equilibrium situation we derive and analyse the system of equations\ndefining the critical surface separating the magnetic regime from the\nnon-magnetic one. An exact analytic solution for the phase boundary as a\nfunction of the applied voltage is found in the symmetric case. Surprisingly,\nwe find that as soon as there is an asymmetry, even small, between the\ncontacts, no finite voltage is able to destroy the magnetic regime which\npersists at arbitrary high voltages.",
        "positive": "Probing magneto-elastic phenomena through an effective spin-bath\n  coupling model: A phenomenological model is constructed, that captures the effects of\ncoupling magnetic and elastic degrees of freedom, in the presence of external,\nstochastic perturbations, in terms of the interaction of magnetic moments with\na bath, whose individual degrees of freedom cannot be resolved and only their\nmesoscopic properties are relevant.\n  In the present work, the consequences of identifying the effects of\ndissipation as resulting from interactions with a bath of spins are explored,\nin addition to elastic, degrees of freedom. The corresponding stochastic\ndifferential equations are solved numerically and the moments of the\nmagnetization are computed. The stochastic equations implicitly define a\nmeasure on the space of spin configurations, whose moments at equal times\nsatisfy a hierarchy of deterministic, ordinary differential equations. Closure\nassumptions are used to truncate the hierarchy and the same moments are\ncomputed. We focus on the advantages and problems that each approach presents,\nfor the approach to equilibrium and, in particular, the emergence of\nlongitudinal damping."
    },
    {
        "anchor": "Quantum antidot as a controllable spin injector and spin filter: We propose a device based on an antidot embedded in a narrow quantum wire in\nthe edge state regime, that can be used to inject and/or to control spin\npolarized current. The operational principle of the device is based on the\neffect of resonant backscattering from one edge state into another through a\nlocalized quasi-bound states, combined with the effect of Zeeman splitting of\nthe quasibound states in sufficiently high magnetic field. We outline the\ndevice geometry, present detailed quantum-mechanical transport calculation and\nsuggest a possible scheme to test the device performance and functionality.",
        "positive": "Nanoscale Magnetic Compasses: We have synthesized nanoscale magnetic compasses with high yield. These\nferromagnetic iron carbide nano-particles, which are encapsulated in a pair of\nparallel carbon needles, change their direction in response to an external\nmagnetic field. Electron holography reveals magnetic fields confined to the\nvicinity of the bicone-shaped particles, which are composed of few\nferromagnetic domains. Aligned magnetically and encapsulated in an acrylate\npolymer matrix, these nanocompasses exhibit anisotropic bulk magnetic\npermeability with an easy axis normal to the needle direction, that can be\nunderstood as a result of the anisotropic demagnetizing field of a nonspherical\nsingle-domain particle. This novel material with orthogonal magnetic and\nstructural axes could be highly useful as magnetic components in\nelectromagnetic wave absorbent materials and magnetorheological fluids."
    },
    {
        "anchor": "Magnetic barriers in graphene nanoribbons: A theoretical study of the transport properties of zigzag and armchair\ngraphene nanoribbons with a magnetic barrier on top is presented. The magnetic\nbarrier modifies the energy spectrum of the nanoribbons locally, which results\nin an energy shift of the conductance steps towards higher energies. The\nmagnetic barrier also induces Fabry-Perot type oscillations, provided the edges\nof the barrier are sufficiently sharp. The lowest propagating state present in\nzigzag and metallic armchair nanoribbons prevent confinement of the charge\ncarriers by the magnetic barrier. Disordered edges in nanoribbons tend to\nlocalize the lowest propagating state, which get delocalized in the magnetic\nbarrier region. Thus, in sharp contrast to the case of two-dimensional\ngraphene, the charge carriers in graphene nanoribbons cannot be confined by\nmagnetic barriers. We also present a novel method based on the Green's function\ntechnique for the calculation of the magnetosubband structure, Bloch states and\nmagnetoconductance of the graphene nanoribbons in a perpendicular magnetic\nfield. Utilization of this method greatly facilitates the conductance\ncalculations, because, in contrast to excising methods, the present method does\nnot require self-consistent calculations for the surface Green's function.",
        "positive": "Disorder-induced stabilization of the quantum Hall ferromagnet: We report on an absolute measurement of the electronic spin polarization of\nthe $\\nu=1$ integer quantum Hall state. The spin polarization is extracted in\nthe vicinity of $\\nu=1$ (including at exactly $\\nu=1$) via resistive NMR\nexperiments performed at different magnetic fields (electron densities), and\nZeeman energy configurations. At the lowest magnetic fields, the polarization\nis found to be complete in a narrow region around $\\nu=1$. Increasing the\nmagnetic field (electron density) induces a significant depolarization of the\nsystem, which we attribute to a transition between the quantum Hall ferromagnet\nand the Skyrmion glass phase theoretically expected as the ratio between\nCoulomb interactions and disorder is increased. These observations account for\nthe fragility of the polarization previously observed in high mobility 2D\nelectron gas, and experimentally demonstrate the existence of an optimal amount\nof disorder to stabilize the ferromagnetic state."
    },
    {
        "anchor": "Controlled Fabrication of Nanogaps in Ambient Environment for Molecular\n  Electronics: We have developed a controlled and highly reproducible method of making\nnanometer-spaced electrodes using electromigration in ambient lab conditions.\nThis advance will make feasible single molecule measurements of macromolecules\nwith tertiary and quaternary structures that do not survive the liquid-helium\ntemperatures at which electromigration is typically performed. A second advance\nis that it yields gaps of desired tunnelling resistance, as opposed to the\nrandom formation at liquid-helium temperatures. Nanogap formation occurs\nthrough three regimes: First it evolves through a bulk-neck regime where\nelectromigration is triggered at constant temperature, then to a few-atom\nregime characterized by conductance quantum plateaus and jumps, and finally to\na tunnelling regime across the nanogap once the conductance falls below the\nconductance quantum.",
        "positive": "Quantum oscillations of the topological surface states in low carrier\n  concentration crystals of Bi$_{2-x}$Sb$_{x}$Te$_{3-y}$Se$_{y}$: We report a high-field magnetotransport study on selected low-carrier\ncrystals of the topological insulator Bi$_{2-x}$Sb${_x}$Te$_{3-y}$Se$_{y}$.\nMonochromatic Shubnikov - de Haas (SdH) oscillations are observed at 4.2~K and\ntheir two-dimensional nature is confirmed by tilting the magnetic field with\nrespect to the sample surface. With help of Lifshitz-Kosevich theory, important\ntransport parameters of the surface states are obtained, including the carrier\ndensity, cyclotron mass and mobility. For $(x,y)=(0.50,1.3)$ the Landau level\nplot is analyzed in terms of a model based on a topological surface state in\nthe presence of a non-ideal linear dispersion relation and a Zeeman term with\n$g_s = 70$ or $-54$. Input parameters were taken from the electronic dispersion\nrelation measured directly by angle resolved photoemission spectroscopy on\ncrystals from the same batch. The Hall resistivity of the same crystal\n(thickness of 40~$\\mu$m) is analyzed in a two-band model, from which we\nconclude that the ratio of the surface conductance to the total conductance\namounts to 32~\\%."
    },
    {
        "anchor": "Quest for Rare Events in three-dimensional Mesoscopic Disordered Metals: The study reports on the first large statistics numerical experiment\nsearching for rare eigenstates of anomalously high amplitudes in\nthree-dimensional diffusive metallic conductors. Only a small fraction of a\nhuge number of investigated eigenfunctions generates the far asymptotic tail of\ntheir amplitude distribution function. The relevance of the relationship\nbetween disorder and spectral averaging, as well as of the quantum transport\nproperties of the investigated mesoscopic samples, for the numerical\nexploration of eigenstate statistics is divulged. The quest provides exact\nresults to serve as a reference point in understanding the limits of\napproximations employed in different analytical predictions, and thereby the\nphysics (quantum vs semiclassical) behind large deviations from the universal\npredictions of random matrix theory.",
        "positive": "Reflection Phase Shift of One-dimensional Plasmon Polaritons in Carbon\n  Nanotubes: We investigated, both experimentally and theoretically, the reflection phase\nshift (RPS) of one-dimensional plasmon polaritons. We launched 1D plasmon\npolaritons in carbon nanotube and probed the plasmon interference pattern using\nscanning near-field optical microscopy (SNOM) technique, through which a\nnon-zero phase shift was observed. We further developed a theory to understand\nthe nonzero phase shift of 1D polaritons, and found that the RPS can be\nunderstood by considering the evanescent field beyond the nanotube end.\nInteresting, our theory shows a strong dependence of RPS on polaritons\nwavelength and nanotube diameter, which is in stark contrast to 2D plasmon\npolaritons in graphene where the RPS is a constant. In short wave region, the\nRPS of 1D polaritons only depends on a dimensionless variable -- the ratio\nbetween polaritons wavelength and nanotube diameter. These results provide\nfundamental insights into the reflection of polaritons in 1D system, and could\nfacilitate the design of ultrasmall 1D polaritonic devices, such as resonators,\ninterferometers."
    },
    {
        "anchor": "Resonant inelastic tunneling in molecular junctions: Within a phonon-assisted resonance level model we develop a self-consistent\nprocedure for calculating electron transport currents in molecular junctions\nwith intermediate to strong electron-phonon interaction. The scheme takes into\naccount the mutual influence of the electron and phonon subsystems. It is based\non the 2nd order cumulant expansion, used to express the correlation function\nof the phonon shift generator in terms of the phonon momentum Green function.\nEquation of motion (EOM) method is used to obtain an approximate analog of the\nDyson equation for the electron and phonon Green functions in the case of\nmany-particle operators present in the Hamiltonian. To zero-order it is similar\nin particular cases (empty or filled bridge level) to approaches proposed\nearlier. The importance of self-consistency in resonance tunneling situations\n(partially filled bridge level) is stressed. We confirm, even for strong\nvibronic coupling, a previous suggestion concerning the absence of phonon\nsidebands in the current vs. gate voltage plot when the source-drain voltage is\nsmall.",
        "positive": "Implementing optimal control pulse shaping for improved single-qubit\n  gates: We employ pulse shaping to abate single-qubit gate errors arising from the\nweak anharmonicity of transmon superconducting qubits. By applying shaped\npulses to both quadratures of rotation, a phase error induced by the presence\nof higher levels is corrected. Using a derivative of the control on the\nquadrature channel, we are able to remove the effect of the anharmonic levels\nfor multiple qubits coupled to a microwave resonator. Randomized benchmarking\nis used to quantify the average error per gate, achieving a minimum of\n0.007+/-0.005 using 4 ns-wide pulse."
    },
    {
        "anchor": "Ultrafast transport and relaxation of hot plasmonic electrons in\n  metal-dielectric heterostructures: We analyze ultrafast electron dynamics in the time domain upon optical\nexcitation of propagating surface plasmon-polaritons (SPs) in metal-dielectric\nheterostructures. Developing a kinetic model where both local and non-local\nelectron relaxation in metals are included, we identify relevant timescales and\nextend the existing non-equilibrium electron dynamics framework onto the case\nof collective electronic excitations. The experimental data obtained in two\ndistinct series of pump-probe measurements (with varied pump wavelength and\nangle of incidence) demonstrate SP-driven, one order of magnitude enhanced\nefficiency of the hot electron generation and the fourfold (up to 200 fs)\nslowdown of their non-local relaxation at the SP resonance. We discuss the\nperspectives of the SP-enabled manipulation of the non-equilibrium electron\npopulation lying at the crossover of photonics and ultrafast spintronics.",
        "positive": "Valley current generation using biased bilayer graphene dots: Intrinsic and extrinsic valley Hall effects are predicted to emerge in\ngraphene systems with uniform or spatially-varying mass terms. Extrinsic\nmechanisms, mediated by the valley-dependent scattering of electrons at the\nFermi surface, can be directly linked to quantum transport simulations. This is\na promising route towards more complete experimental investigation of\nvalleytronic phenomena in graphene, but a major obstacle is the difficulty in\napplying the sublattice-dependent potentials required. Here we show that\nstrongly valley-dependent scattering also emerges from bilayer graphene quantum\ndots, where the gap size can be easily modulated using the interlayer\npotentials in dual-gated devices. Robust valley-dependent scattering and\nconcomitant valley currents are observed for a range of systems, and we\ninvestigate the role of dot size, mass strength and additional potential terms.\nFinally, we note that a strong valley splitting of electronic current also\nemerges when a biased bilayer dot is embedded in a single layer of graphene,\nbut that the effect is less robust than for a bilayer host. Our findings\nsuggest that bilayer graphene devices with custom mass profiles provide an\nexcellent platform for future valleytronic exploration of two-dimensional\nmaterials."
    },
    {
        "anchor": "Aniotropy of in-plane g-factor of electrons in HgTe quantum wells: The results of experimental studies of the Shubnikov-de Haas (SdH) efect in\nthe (013)-HgTe/Hg$_{1-x}$Cd$_x$Te quantum wells (QWs) of electron type of\nconductivity both with normal and inverted energy spectrum are reported.\nComprehensive analysis of the SdH oscillations measured for the different\norientations of magnetic field relative to the quantum well plane and\ncrystallographic exes allows us to investigate the anisotropy of the Zeeman\neffect. For the QWs with inverted spectrum, it has been shown that the ratio of\nthe spin splitting to the orbital one is strongly dependent not only on the\norientation of the magnetic field relative to the QW plane but also on the\norientation of the in-plane magnetic field component relative to\ncrystallographic axes laying in the QW plane that implies the strong anisotropy\nof in-plane g-factor. In the QW with normal spectrum, this ratio strongly\ndepends on the angle between the magnetic field and the normal to the QW plane\nand reveals a very slight anisotropy in the QW plane. To interpret the data,\nthe Landau levels in the tilted magnetic field are calculated within the\nframework of four-band \\emph{kP} model. It is shown that the experimental\nresults can be quantitatively described only with taking into account the\ninterface inversion asymmetry.",
        "positive": "Description of statistical switching in perpendicular STT-MRAM within an\n  analytical and numerical micromagnetic framework: The realistic modeling of STT-MRAM for the simulations of hybrid\nCMOS/Spintronics devices in comprehensive simulation environments require a\nfull description of stochastic switching processes in state of the art\nSTT-MRAM. Here, we derive an analytical formulation that takes into account the\nspin-torque asymmetry of the spin polarization function of magnetic tunnel\njunctions studying. We studied its validity range by comparing the analytical\nformulas with results achieved numerically within a full micromagnetic\nframework. We also find that a reasonable fit of the probability density\nfunction (PDF) of the switching time is given by a Pearson Type IV PDF. The\nmain results of this work underlines the need of data-driven design of STT-MRAM\nthat uses a full micromagnetic simulation framework for the statistical\nproprieties PDF of switching processes."
    },
    {
        "anchor": "Electron transport through a mesoscopic metal-CDW-metal junction: In this work we study the transport properties of a finite Peierls-Fr\\\"ohlich\ndielectric with a charge density wave of the commensurate type. We show that at\nlow temperatures this problem can be mapped onto a problem of fractional charge\ntransport through a finite-length correlated dielectric, recently studied by\nPonomarenko and Nagaosa [Phys. Rev. Lett {\\bf 81}, 2304 (1998)]. The\ntemperature dependence of conductance of the charge density wave junction is\npresented for a wide range of temperatures.",
        "positive": "Exciton-Polariton Oscillations in Real Space: We introduce and model spin-Rabi oscillations based on exciton-polaritons in\nsemiconductor microcavities. The phase and polarization of oscillations can be\ncontrolled by resonant coherent pulses and the propagation of oscillating\ndomains gives rise to phase-dependent interference patterns in real space. We\nshow that interbranch polariton-polariton scattering controls the propagation\nof oscillating domains, which can be used to realize logic gates based on an\nanalogue variable phase."
    },
    {
        "anchor": "Bipolar electron waveguides in two-dimensional materials with tilted\n  Dirac cones: We show that the (2+1)-dimensional massless Dirac equation, which includes a\ntilt term, can be reduced to the biconfluent Heun equation for a broad range of\nscalar confining potentials, including the well-known Morse potential. Applying\nthese solutions, we investigate a bipolar electron waveguide in 8-$Pmmn$\nborophene, formed by a well and barrier, both described by the Morse potential.\nWe demonstrate that the ability of two-dimensional materials with tilted Dirac\ncones to localize electrons in both a barrier and a well can be harnessed to\ncreate pseudogaps in their electronic spectrum. These pseudogaps can be tuned\nthrough varying the applied top-gate voltage. Potential opto-valleytronic and\nterahertz applications are discussed.",
        "positive": "Spin domains in one-dimensional conservative polariton solitons: We report stable orthogonally polarised domains in high-density polariton\nsolitons propagating in a semiconductor microcavity wire. This effect arises\nfrom spin dependent polariton-polariton interactions and pump-induced imbalance\nof polariton spin populations. The interactions result in an effective magnetic\nfield acting on polariton spin across the soliton profile, leading to the\nformation of polarisation domains. Our experimental findings are in excellent\nagreement with theoretical modelling taking into account these effects."
    },
    {
        "anchor": "Ultrafast generation of skyrmionic defects with vortex beams: printing\n  laser profiles on magnets: Controlling electric and magnetic properties of matter by laser beams is\nactively explored in the broad region of condensed matter physics, including\nspintronics and magneto-optics. Here we theoretically propose an application of\noptical and electron vortex beams carrying intrinsic orbital angular momentum\nto chiral ferro- and antiferro- magnets. We analyze the time evolution of spins\nin chiral magnets under irradiation of vortex beams, by using the stochastic\nLandau-Lifshitz-Gilbert equation. We show that beam-driven nonuniform\ntemperature lead to a class of ring-shaped magnetic defects, what we call\nskyrmion multiplex, as well as conventional skyrmions. We discuss the proper\nbeam parameters and the optimal way of applying the beams for the creation of\nthese topological defects. Our findings provide an ultrafast scheme of\ngenerating topological magnetic defects in a way applicable to both metallic\nand insulating chiral (anti-) ferromagnets.",
        "positive": "The von Neumann-Wigner theorem in quantum dot molecules: We show that electrons in coupled quantum dots characterized by high aspect\nratios undergo abrupt density rotations when the dots are biased into an\nasymmetric confinement configuration. Density rotations occur with electron\ntransfer to a single dot, and give rise to sharp variations of the exchange\ncoupling between electrons as a function of inter-dot detuning. Our analysis\nbased on exact diagonalization technique indicates that this unusual behavior\nis in agreement with the von Neumann-Wigner theorem that dictates the\nvariations of the energy spectrum from the symmetries of the molecular states\nduring the detuning process. It is also shown that the overall effect is\nquenched by the presence of magnetic fields, which by adding angular momentum\nto the electron motion affects the spatial symmetry of the molecular states."
    },
    {
        "anchor": "Super-localization of excitons in carbon nanotubes at cryogenic\n  temperature: At cryogenic temperature and at the single emitter level, the optical\nproperties of single-wall carbon nanotubes depart drastically from that of a\none-dimensional (1D) object. In fact, the (usually unintentional) localization\nof excitons in local potential wells leads to nearly 0D behaviors such as\nphoton antibunching, spectral diffusion, inhomogeneous broadening, etc. Here,\nwe present an hyperspectral imaging of this exciton self-localization effect at\nthe single nanotube level using a super-resolved optical microscopy approach.\nWe report on the statistical distribution of the traps localization, depth and\nwidth. We use a quasi-resonant photoluminescence excitation approach to probe\nthe confined quantum states. Numerical simulations of the quantum states and\nexciton diffusion show that the excitonic states are deeply modified by the\ninterface disorder inducing a remarkable discretization of the excitonic\nabsorption spectrum and a quenching of the free 1D exciton absorption.",
        "positive": "Controlling the Spin Torque Efficiency with Ferroelectric Barriers: Non-equilibrium spin-dependent transport in magnetic tunnel junctions\ncomprising a ferroelectric barrier is theoretically investigated. The exact\nsolutions of the free electron Schr\\\"odinger equation for electron tunneling in\nthe presence of interfacial screening are obtained by combining Bessel and Airy\nfunctions. We demonstrate that the spin transfer torque efficiency, and more\ngenerally the bias-dependence of tunneling magneto- and electroresistance, can\nbe controlled by switching the ferroelectric polarization of the barrier. This\neffect provides a supplementary way to electrically control the current-driven\ndynamic states of the magnetization and related magnetic noise in spin transfer\ndevices."
    },
    {
        "anchor": "Non-Volatile Control of Valley Polarized Emission in 2D WSe2-AlScN\n  Heterostructures: Achieving robust and electrically controlled valley polarization in monolayer\ntransition metal dichalcogenides (ML-TMDs) is a frontier challenge for\nrealistic valleytronic applications. Theoretical investigations show that\nintegration of 2D materials with ferroelectrics is a promising strategy;\nhowever, its experimental demonstration has remained elusive. Here, we\nfabricate ferroelectric field-effect transistors using a ML-WSe2 channel and a\nAlScN ferroelectric dielectric, and experimentally demonstrate efficient tuning\nas well as non-volatile control of valley polarization. We measured a large\narray of transistors and obtained a maximum valley polarization of ~27% at 80 K\nwith stable retention up to 5400 secs. The enhancement in the valley\npolarization was ascribed to the efficient exciton-to-trion (X-T) conversion\nand its coupling with an out-of-plane electric field, viz. the quantum-confined\nStark effect. This changes the valley depolarization pathway from strong\nexchange interactions to slow spin-flip intervalley scattering. Our research\ndemonstrates a promising approach for achieving non-volatile control over\nvalley polarization and suggests new design principles for practical\nvalleytronic devices.",
        "positive": "Dynamics of supported ultrathin molybdenum films driven by strong short\n  laser impact: We consider expansion, break off, and flight of 10 nm molybdenum film\ndeposited onto glass support. These events are initiated by action of\nsubpicosecond laser pulse onto film. Approximations for two-temperature\nequation of state and electron--ion coupling parameter are developed. Heat\nconduction is unimportant because film is ultrathin and because radius of a\nlaser beam is rather large $\\sim 10$ $\\mu$m (thus lateral thermal spreading is\ninsignificant at the considered time scale). We use two-temperature\none-dimensional hydrodynamic code to follow evolution of laser induced flow.\nAdditional code for treating transmission and reflection of a monochromatic\nelectromagnetic wave is developed. It is applied to describe interference\nbetween transmitted and reflected waves in the layered structure appearing\nthanks to laser induced expansion and separation of a film."
    },
    {
        "anchor": "Zigzag Phase Transition in Quantum Wires: We study the quantum phase transition of interacting electrons in quantum\nwires from a one-dimensional (1D) linear configuration to a quasi-1D zigzag\narrangement using quantum Monte Carlo methods. As the density increases from\nits lowest values, first, the electrons form a linear Wigner crystal; then, the\nsymmetry about the axis of the wire is broken as the electrons order in a\nquasi-1D zigzag phase; and, finally, the electrons form a disordered\nliquid-like phase. We show that the linear to zigzag phase transition is not\ndestroyed by the strong quantum fluctuations present in narrow wires; it has\ncharacteristics which are qualitatively different from the classical\ntransition.",
        "positive": "Stray magnetic fields from elliptical-shaped and stadium-shaped\n  ferromagnets: An artificial spin ice consisting of numerous ferromagnets has attracted\nattention because of its applicability to practical devices. The ferromagnets\ninteract through their stray magnetic field and show various functionality. The\nferromagnetic element in the spin ice was recently made in elliptical-shape or\nstadium-shape. The former has a narrow edge, expecting to generate a large\nstray magnetic field. The latter has a large volume and is also expected to\ngenerate a large stray magnetic field. Here, we estimate the stray magnetic\nfield by numerically integrating the solution of the Poisson equation. When\nmagnetization is parallel to an easy axis, the elliptical-shaped ferromagnet\ngenerates a larger stray magnetic field than the stadium-shaped ferromagnet.\nThe stray magnetic fields from both ferromagnets for arbitrary magnetization\ndirections are also investigated."
    },
    {
        "anchor": "Soliton motion induced along ferromagnetic skyrmion chains in chiral\n  thin nanotracks: Using atomistic magnetic simulations we investigate the soliton motion along\na pinned skyrmion chain containing an interstitial skyrmion. We find that the\nsoliton can exhibit stable motion along the chain without a skyrmion Hall\neffect for an extended range of drives. Under a constant drive the solitons\nhave a constant velocity. We also measure the skyrmion velocity-current curves\nand identify the signatures of different phases including a pinned phase,\nstable soliton motion, and quasi-free motion at higher drives where all of the\nskyrmions depin from the pinning centers and move along the rigid wall. In the\nquasi-free motion regime, the velocity is oscillatory due to the motion of the\nskyrmions over the pinning sites. For increasing pinning strength, the onset of\nsoliton motion shifts to higher values of current density. We also find that\nfor stronger pinning, the characteristic velocity-current shape is affected by\nthe annihilation of single or multiple skyrmions in the drive interval over\nwhich the soliton motion occurs. Our results indicate that stable skyrmion\nsoliton motion is possible and could be useful for technological applications.",
        "positive": "First Principles Study of Bismuth Films on the Nickel(111) Surface: A recent experiment(Bollmann11) suggested that bismuth forms hexagonal close\npacked (HCP) films on the Ni(111) surface, of heights 3, 5 and 7 layers. A\nquantum size effect based on free electrons was proposed in explanation. To\ntest this idea, we calculate the total energies of Bi on the Ni(111) surface\nusing density functional theory. We find that HCP film stabilities disagree\nwith the observed odd layer preferences, and the structures are mechanically\ndestabilized by adding capping atoms which pucker the HCP layers. Furthermore,\nwe find that rhombohedral films based on the bulk Bi structure are\nenergetically more favorable than the proposed HCP films. These structures also\nfavor odd numbers of layers, but owing to covalent chemical bonding rather than\nconfinement of free electrons. Specifically, a strongly bound adsorbed surface\nmonolayer forms, followed by bulk-like rhombohedral bilayers."
    },
    {
        "anchor": "Strain-induced pseudomagnetic field in Dirac semimetal borophene: A tight-binding model of 8-Pmmn borophene, a two-dimensional boron crystal,\nis developed. We confirm that the crystal hosts massless Dirac fermions and the\nDirac points are protected by symmetry. Strain is introduced into the model,\nand it is shown to induce a pseudomagnetic field vector potential and a scalar\npotential. The dependence of the potentials on the strain tensor is calculated.\nThe physical effects controlled by pseudomagnetic field are discussed.",
        "positive": "Effective action for quantum Hall skyrmions: Recently, an O(3) type of effective action was proposed for the quantum Hall\nferromagnet, which accounts for bag formation observed in microscopic Hartree-\nFock calculations. We apply this action in the soliton sector and compare with\nHartree-Fock results. We find good agreement over the whole parameter range\nwhere skyrmions exist. The standard minimal O(3) model cannot explain the bag\nand has further shortcomings connected with that fact."
    },
    {
        "anchor": "Pseudo-magnetic catalysis of the time-reversal symmetry breaking in\n  graphene: Finite flux of the (time-reversal-symmetric) pseudo-magnetic field, which\nrepresents the effect of wrinkling of the graphene sheet for example, is shown\nto be a catalyst for spontaneous breaking of the time-reversal symmetry of\nDirac fermions in two dimensions. Possible experimental consequences of this\neffect for graphene are discussed.",
        "positive": "Atomic-scale control of graphene magnetism using hydrogen atoms: Isolated hydrogen atoms absorbed on graphene are predicted to induce magnetic\nmoments. Here we demonstrate that the adsorption of a single hydrogen atom on\ngraphene induces a magnetic moment characterized by a ~20 meV spin-split state\nat the Fermi energy. Our scanning tunneling microscopy (STM) experiments,\ncomplemented by first-principles calculations, show that such a spin-polarized\nstate is essentially localized on the carbon sublattice complementary to the\none where the H atom is chemisorbed. This atomically modulated spin-texture,\nwhich extends several nanometers away from the H atom, drives the direct\ncoupling between the magnetic moments at unusually long distances. Using the\nSTM tip to manipulate H atoms with atomic precision, we demonstrate the\npossibility to tailor the magnetism of selected graphene regions."
    },
    {
        "anchor": "Effect of the Gate-dielectric stack on the quantum screening of the\n  two-dimensional electron gas in silicon inversion layer: This article develops a consistent theory of free carrier screening of a\ntwo-dimensional electron gas in the silicon inversion layer in the presence of\nstacked layers of dielectric environment-commonly knows as gate stack in\ncontext of field-effect transistors. It is shown that the finite thickness and\nof dielectric stacks alters the free carrier screening, a crucial quantity,\nwhich determines screened coulomb interaction in the inversion layer, and\nubiquitously appears in carrier transport theory in semiconductors. Results are\nanalytical and can be used to accurate prediction Coulomb-interaction limited\nmobility in field-effect transistors.",
        "positive": "Laser pulse waveform control of Dirac fermions in graphene: We theoretically study the Dirac fermion dynamics in a graphene monolayer in\nthe presence of an applied ultrafast laser pulse. The pulse has the duration of\na few femtoseconds and the amplitude of ~ 0.1 - 0.5 $\\mathrm{V/\\AA}$. The\nwaveform of the pulse is described by Hermit Gaussian polynomials with varying\ncarrier-envelope phase. We show that the ultrafast dynamics of Dirac fermions\nstrongly depends on the carrier-envelope phase and the frequency of the applied\npulse. The ultrafast pulse generates an electric current which results in a\nfinite transferred charge. The ultrafast field-driven current and the\ncorresponding net transferred charge depend on the waveform of the applied\npulse. Our results pave the way for the development of ultrafast information\nprocessing in the terahertz domain."
    },
    {
        "anchor": "Spin polarisation and spin dependent scattering of holes in transverse\n  magnetic focussing: In 2D systems with a spin-orbit interaction, magnetic focussing can be used\nto create a spatial separation of particles with different spin. Here we\nmeasure hole magnetic focussing for two different magnitudes of the Rashba\nspin-orbit interaction. We find that when the Rashba spin-orbit magnitude is\nlarge there is significant attenuation of one of the focussing peaks, which is\nconventionally associated with a change in the spin polarisation. We instead\nshow that in hole systems with a $k^3$ spin-orbit interaction, this peak\nsuppression is due to a change in the scattering of one spin state, not a\nchange in spin polarisation. We also show that the change in scattering length\nextracted from magnetic focussing is consistent with results obtained from\nmeasurements of Shubnikov-de Haas oscillations. This result suggests that\nscattering must be considered when relating focussing peak amplitude to spin\npolarisation in hole systems",
        "positive": "Quantized Charge Pumping through a Carbon Nanotube Double Quantum Dot: We demonstrate single-electron pumping in a gate-defined carbon nanotube\ndouble quantum dot. By periodic modulation of the potentials of the two quantum\ndots we move the system around charge triple points and transport exactly one\nelectron or hole per cycle. We investigate the pumping as a function of the\nmodulation frequency and amplitude and observe good current quantization up to\nfrequencies of 18 MHz where rectification effects cause the mechanism to break\ndown."
    },
    {
        "anchor": "Monolayer-to-mesoscale modulation of the optical properties in 2D CrI3\n  mapped by hyperspectral microscopy: Magnetic 2D materials hold promise to change the miniaturization paradigm of\nunidirectional photonic components. However, the integration of these materials\nin devices hinges on the accurate determination of the optical properties down\nto the monolayer limit, which is still missing. By using hyperspectral\nwide-field imaging we reveal a non-monotonic thickness dependence of the\ncomplex optical dielectric function in the archetypal magnetic 2D material CrI3\nextending across different length scales: onsetting at the mesoscale, peaking\nat the nanoscale and decreasing again down to the single layer. These results\nportray a modification of the electronic properties of the material and align\nwith the layer-dependent magnetism in CrI3, shedding light into the\nlong-standing structural conundrum in this material. The unique modulation of\nthe complex dielectric function from the monolayer up to more than 100 layers\nwill be instrumental for understanding and manipulating the magneto-optical\neffects of magnetic 2D materials.",
        "positive": "Shot Noise of a Temperature-Biased Tunnel Junction: We report the measurement of the current noise of a tunnel junction driven\nout-of-equilibrium by a temperature and/or voltage difference, i.e. the charge\nnoise of heat and/or electrical current. This is achieved by a careful control\nof electron temperature below 1 K at the nanoscale, and a sensitive measurement\nof noise with wide bandwidth, from 0.1 to 1 GHz. An excellent agreement between\nexperiment and theory with no fitting parameter is obtained. In particular, we\nfind that the current noise of the junction of resistance R when one electrode\nis at temperature T and the other one at zero temperature is given by S = 2 ln2\nkB T /R."
    },
    {
        "anchor": "Magnetization dynamics in synthetic antiferromagnets: Role of dynamical\n  energy and mutual spin pumping: We investigate magnetization dynamics in asymmetric interlayer exchange\ncoupled Py/Ru/Py trilayers using both vector network analyzer-based and\nelectrically detected ferromagnetic resonance techniques. Two different\nferromagnetic resonance modes, in-phase and out-of-phase, are observed across\nall three regimes of the static magnetization configurations, through\nantiparallel alignment at low fields, the spin-flop transition at intermediate\nfields, and parallel alignment at high fields. The nonmonotonic behavior of the\nmodes as a function of the external field is explained in detail by analyzing\nthe interlayer exchange and Zeeman energies and is found to be solely governed\nby the interplay of their dynamical components. In addition, the linewidths of\nboth modes were determined across the three regimes and the different behaviors\nof the linewidths versus external magnetic field are attributed to mutual spin\npumping induced in the samples. Interestingly, the difference between the\nlinewidths of the out-of-phase and in-phase modes decreases at the spin-flop\ntransition and is reversed between the antiparallel and parallel aligned\nmagnetization states.",
        "positive": "Magnetic Properties of Dirac Fermions in a Buckled Honeycomb Lattice: We calculate the magnetic response of a buckled honeycomb lattice with\nintrinsic spin-orbit coupling (such as silicene) which supports valley-spin\npolarized energy bands when subjected to a perpendicular electric field $E_z$.\nBy changing the magnitude of the external electric field, the size of the two\nband gaps involved can be tuned, and a transition from a topological insulator\n(TI) to a trivial band insulator (BI) is induced as one of the gaps becomes\nzero, and the system enters a valley-spin polarized metallic state (VSPM). In\nan external magnetic field ($B$), a distinct signature of the transition is\nseen in the derivative of the magnetization with respect to chemical potential\n($\\mu$) which gives the quantization of the Hall plateaus through the Streda\nrelation. When plotted as a function of the external electric field, the\nmagnetization has an abrupt change in slope at its minimum which signals the\nVSPM state. The magnetic susceptibility ($\\chi$) shows jumps as a function of\n$\\mu$ when a band gap is crossed which provides a measure of the gaps'\nvariation as a function of external electric field. Alternatively, at fixed\n$\\mu$, the susceptibility displays an increasingly large diamagnetic response\nas the electric field approaches the critical value of the VSPM phase. In the\nVSPM state, magnetic oscillations exist for any value of chemical potential\nwhile for the TI, and BI state, $\\mu$ must be larger than the minimum gap in\nthe system. When $\\mu$ is larger than both gaps, there are two fundamental\ncyclotron frequencies (which can also be tuned by $E_z$) involved in the\nde-Haas van-Alphen oscillations which are close in magnitude. This causes a\nprominent beating pattern to emerge."
    },
    {
        "anchor": "Field Theory on the von Neumann Lattice and the Quantized Hall\n  Conductance of Bloch Electrons: We construct useful sets of one-particle states in the quantum Hall system\nbased on the von Neumann lattice. Using the set of momentum states, we develop\na field-theoretical formalism and apply the formalism to the system subjected\nto a periodic potential. The topological formula of the Hall conductance\nwritten by the winding number of propagator is generalized to Bloch electrons.\nThe relation between the winding number and the Chern number is clarified.",
        "positive": "Coulomb drag in phase-coherent mesoscopic structures - Numerical study\n  of disordered 1D-wires: We study Coulomb drag between two parallel disordered mesoscopic 1D-wires. By\nnumerical ensemble averaging we calculate the statistical properties of the\ntransconductance G_21 including its distribution. For wires with mutually\nuncorrelated disorder potentials we find that the mean value is finite, but\nwith comparable fluctuations so that sign-reversal is possible. For identical\ndisorder potentials the mean value and the fluctuations nare enhanced compared\nto the case of uncorrelated disorder."
    },
    {
        "anchor": "Nonlocal Friction Forces in the Particle-Plate and Plate-Plate\n  Configurations: Nonretarded Approximation: In the nonrelativistic approximation of fluctuation electrodynamics, using\nthe specular reflection model and the nonlocal dielectric permittivity of a\nmetal, we obtained simple analytical expressions for the friction forces in the\nparticle-plate and plate-plate systems upon relative motion of the bodies with\nconstant velocity. It is shown that at separations of about 1{\\div}10 nm, for\nan Au nanoparticle (or a gold plate) moving near another gold plate at rest,\nthe dissipative forces are 2 to 4 orders of magnitude higher than in the case\nwhen the local Drude dielectric permittivity is used.",
        "positive": "Exponential Protection of Zero Modes in Majorana Islands: Majorana zero modes are quasiparticle excitations in condensed matter systems\nthat have been proposed as building blocks of fault-tolerant quantum computers\n[1]. They are expected to exhibit non-Abelian particle statistics, in contrast\nto the usual statistics of fermions and bosons, enabling quantum operations to\nbe performed by braiding isolated modes around one another. Quantum braiding\noperations are topologically protected insofar as these modes are pinned near\nzero energy, and the pinning is predicted to be exponential as the modes become\nspatially separated. Following theoretical proposals, several experiments have\nidentified signatures of Majorana modes in proximitized nanowires and atomic\nchains, with small mode-splitting potentially explained by hybridization of\nMajoranas. Here, we use Coulomb-blockade spectroscopy in an InAs nanowire\nsegment with epitaxial aluminum, which forms a proximity-induced\nsuperconducting Coulomb island (a Majorana island) that is isolated from\nnormal-metal leads by tunnel barriers, to measure the splitting of\nnear-zero-energy Majorana modes. We observe exponential suppression of energy\nsplitting with increasing wire length. For short devices of a few hundred\nnanometers, sub-gap state energies oscillate as the magnetic field is varied,\nas is expected for hybridized Majorana modes. Splitting decreases by a factor\nof about ten for each half micrometer of increased wire length. For devices\nlonger than about one micrometer, transport in strong magnetic fields occurs\nthrough a zero-energy state that is energetically isolated from a continuum,\nyielding uniformly spaced Coulomb-blockade conductance peaks, consistent with\nteleportation via Majorana modes. Our results help explain the\ntrivial-to-topological transition in finite systems and to quantify the scaling\nof topological protection with end-mode separation."
    },
    {
        "anchor": "Dynamical axion state with hidden pseudospin Chern numbers in\n  MnBi$_{2}$Te$_{4}$-based heterostructures: Axion is a hypothetical elementary particle which was initially postulated to\nsolve the charge conjugation-parity problem in particle physics. Interestingly,\nthe axion state has emerged in effective theory of topological insulators and\nhas attracted extensive attention in condensed matter physics. Time-reversal or\ninversion symmetry constrains the axion field $\\theta$ to be quantized. When\nboth the time-reversal and inversion symmetries are broken by, say, an\nantiferromagnetic order, the axion field $\\theta$ could become unquantized and\ndynamical along with magnetic fluctuations, which is termed the dynamical axion\nfield. Here, we reveal that a wide class of topological-insulator-based\ndynamical axion states could be distinguished from the normal-insulator-based\nones by a hidden quantity derived from the pseudospin Chern number. Motivated\nby recent research on MnBi$_{2}$Te$_{4}$-family materials, we further show that\nsuch topological-insulator-based dynamical axion states can be hopefully\nachieved in MnBi$_{2}$Te$_{4}$-based heterostructures, which should greatly\nfacilitate the study of axion electrodynamics in condensed matter physics.",
        "positive": "Charged exctions in the fractional quantum Hall regime: We study the photoluminescence spectrum of a low density ($\\nu <1$)\ntwo-dimensional electron gas at high magnetic fields and low temperatures. We\nfind that the spectrum in the fractional quantum Hall regime can be understood\nin terms of singlet and triplet charged-excitons. We show that these spectral\nlines are sensitive probes for the electrons compressibility. We identify the\ndark triplet charged-exciton and show that it is visible at the spectrum at\n$T<2$ K. We find that its binding energy scales like $e^{2}/l $, where $l$ is\nthe magnetic length, and it crosses the singlet slightly above 15 T."
    },
    {
        "anchor": "Realizing lateral wrap-gated nanowire FETs: Controlling gate length with\n  chemistry rather than lithography: An important consideration in miniaturizing transistors is maximizing the\ncoupling between the gate and the semiconductor channel. A nanowire with a\ncoaxial metal gate provides optimal gate-channel coupling, but has only been\nrealized for vertically oriented nanowire transistors. We report a method for\nproducing laterally oriented wrap-gated nanowire field-effect transistors that\nprovides exquisite control over the gate length via a single wet etch step,\neliminating the need for additional lithography beyond that required to define\nthe source/drain contacts and gate lead. It allows the contacts and nanowire\nsegments extending beyond the wrap-gate to be controlled independently by\nbiasing the doped substrate, significantly improving the sub-threshold\nelectrical characteristics. Our devices provide stronger, more symmetric gating\nof the nanowire, operate at temperatures between 300 to 4 Kelvin, and offer new\nopportunities in applications ranging from studies of one-dimensional quantum\ntransport through to chemical and biological sensing.",
        "positive": "Phonon heat conduction in layered anisotropic crystals: The thermal properties of anisotropic crystals are of both fundamental and\npractical interest, but transport phenomena in anisotropic materials such as\ngraphite remain poorly understood because solutions of the Boltzmann equation\noften assume isotropy. Here, we extend an analytical solution of the Boltzmann\nequation to highly anisotropic solids and examine its predictions for graphite.\nWe show that the phonon mean free paths in the cross-plane direction can be\ncomparable to those in the in-plane direction despite the low cross-plane\nthermal conductivity, which instead arises primarily from the differences in\ngroup velocities and phonon frequencies supported along each direction.\nAdditionally, we demonstrate a method to reconstruct the anisotropic mean free\npath spectrum of crystals with arbitrary dispersion relations without any prior\nknowledge of their harmonic or anharmonic properties using observations of\nquasiballistic heat conduction."
    },
    {
        "anchor": "Tuning of Bilayer Graphene Heterostructure by Horizontally Incident\n  Circular Polarized Light: We theoretically investigated the Floquet states of bilayer graphene\nheterostructure under the irradiation by horizontally incident circular\npolarized light. The in-plane and out-of-plane electric field of the light\nperiodically perturbs the intra-layer and inter-layer hopping, respectively.\nFor circular polarized light, the two components of the electric field has\n$\\pi/2$ phase difference, so that the two types of hopping are periodically\nperturbed with the $\\pi/2$ phase difference, which modify the effective\ninter-layer hopping. We focus on the model of bilayer graphene in the\nheterostructure of antiferromagnetic van der Walls spin valve. The amplitude of\nthe irradiation can tune the band gap and topological properties of the bulk\nstate. The spin-polarized quantum anomalous Hall phase with Chern number being\none is predicted. The incident angle of the irradiation can tune the band gap\nand dispersion of the edge states in zigzag nanoribbons.",
        "positive": "Thermal power of heat flow through a qubit: In this paper we consider thermal power of a heat flow through a qubit\nbetween two baths. The baths are modeled as set of harmonic oscillators\ninitially at equilibrium, at two temperatures. Heat is defined as the change of\nenergy of the cold bath, and thermal power is defined as expected heat per unit\ntime, in the long-time limit. The qubit and the baths interact as in the\nspin-boson model, i.e. through qubit operator $\\sigma_z$. We compute thermal\npower in an approximation analogous to `non-interacting blip' (NIBA) and\nexpress it in the polaron picture as products of correlation functions of the\ntwo baths, and a time derivative of a correlation function of the cold bath. In\nthe limit of weak interaction we recover known results in terms of a sum of\ncorrelation functions of the two baths, a correlation functions of the cold\nbath only, and the energy split."
    },
    {
        "anchor": "Symmetry-broken dissipative exchange flows in thin-film ferromagnets\n  with in-plane anisotropy: Planar ferromagnetic channels have been shown to theoretically support a\nlong-range ordered and coherently precessing state where the balance between\nlocal spin injection at one edge and damping along the channel establishes a\ndissipative exchange flow, sometimes referred to as a spin superfluid. However,\nrealistic materials exhibit in-plane anisotropy, which breaks the axial\nsymmetry assumed in current theoretical models. Here, we study dissipative\nexchange flows in a ferromagnet with in-plane anisotropy from a dispersive\nhydrodynamic perspective. Through the analysis of a boundary value problem for\na damped sine-Gordon equation, dissipative exchange flows in a ferromagnetic\nchannel can be excited above a spin current threshold that depends on material\nparameters and the length of the channel. Symmetry-broken dissipative exchange\nflows display harmonic overtones that redshift the fundamental precessional\nfrequency and lead to a reduced spin pumping efficiency when compared to their\nsymmetric counterpart. Micromagnetic simulations are used to verify that the\nanalytical results are qualitatively accurate, even in the presence of nonlocal\ndipole fields. Simulations also confirm that dissipative exchange flows can be\ndriven by spin transfer torque in a finite-sized region. These results\ndelineate the important material parameters that must be optimized for the\nexcitation of dissipative exchange flows in realistic systems.",
        "positive": "3D Hypersound Microscopy of Van der Waals Heterostructures: We employ here a picosecond ultrasonic technique to study Van der Waals\nheterostructures. Temporal variation of the reflection coefficient of the Al\nfilm that covers Van der Waals hBN/WSe$_2$/hBN heterostructures on a sapphire\nsubstrate after the femtosecond laser pulse excitation is carefully measured\nusing an interferometric technique with spatial resolution. The laser pulse\ngenerates a broadband sound wave packet in aluminum film propagating\nperpendicular to the plane direction and partially reflecting from the\nheterostructural interfaces. The demonstrated technique has enough sensitivity\nto resolve a WSe$_2$ monolayer embedded in hBN. We apply a multilayered model\nof the optical and acoustical response that allows to evaluate the mechanical\nparameters, in particular, rigidity of interfaces, inaccessible from the other\nmeasurements. Mapping of the Fourier spectra of the response clearly visualizes\ndifferent composition regions and can therefore serve as an acoustic tomography\ntool. Our findings demonstrate almost zero acoustic phonon dissipation below\n150 GHz at the interfaces and in the layers that makes Van der Waals\nheterostructures perspective for nano-acoustical applications."
    },
    {
        "anchor": "Modelling charge transport in gold nanogranular films: Cluster-assembled metallic films show interesting electrical properties, both\nin the near-to-percolation regime, when deposited clusters do not form a\ncomplete layer yet, and when the film thickness is well above the electrical\npercolation threshold. Correctly estimating their electrical conductivity is\ncrucial, but, particularly for the latter regime, standard theoretical tools\nare not quite adequate. We therefore developed a procedure based on an\natomically informed mesoscopic model in which ab-initio estimates of electronic\ntransport at the nanoscale are used to reconstruct the conductivity of\nnanogranular gold films generated by molecular dynamics. An equivalent resistor\nnetwork is developed, appropriately accounting for ballistic transport. The\nmethod is shown to correctly capture the non-monotonic behavior of the\nconductivity as a function of the film thickness, namely a signature feature of\nnanogranular films.",
        "positive": "Phase Filters for a Novel Kind of Asymmetric Transport: We present the concept of nonreciprocal interferometers. These two-way\ndevices let particles pass in both directions, but in one direction break the\nphase of the particles' wave functions. Such filters can be realized by using,\nfor example, asymmetric quantum rings. Furthermore, we propose arrangements of\nthese interferometers to obtain larger interferometers which are expected to\nexhibit a puzzling behavior that resembles Maxwell demon action. We indicate an\nopportunity to resolve this puzzle experimentally."
    },
    {
        "anchor": "Thermal orientation of electron spins: It is shown that the spin orientation of free electrons occurs in\nlow-symmetry semiconductor structures if only the electron gas is driven out of\nthermal equilibrium with the crystal lattice. The proposed mechanism of such a\nthermal orientation of electron spins is based on spin dependence of the\nelectron-phonon interaction which tends to restore equilibrium. The microscopic\ntheory of the effect is developed here for asymmetric (110)-grown quantum wells\nwhere the electron gas heating leads to the spin orientation along the [1-10]\naxis in the quantum well plane.",
        "positive": "Compensation of the spin of a quantum dot at Coulomb blockade: We discuss a new entangled state that has been observed in the conduction\nacross a quantum dot. At Coulomb blockade, electrons from the contacts\ncorrelate strongly to those localized in the dot, due to cotunneling processes.\nBecause of the strong Coulomb repulsion on the dot, its electron number is\nunchanged w.r.to the dot in isolation, but the total spin is fully or partly\ncompensated. In a dot with N=even at the singlet-triplet crossing, which occurs\nin large magnetic field, Kondo correlations lead to a total spin S=1/2."
    },
    {
        "anchor": "Study of Spin-Orbit Interactions and Interlayer Ferromagnetic Coupling\n  in Co/Pt/Co Trilayers in Wide Range of Heavy Metal Thickness: The spin-orbit torque, a torque induced by a charge current flowing through\nthe heavy-metal conducting layer with strong spin-orbit interactions, provides\nan efficient way to control the magnetization direction in\nheavy-metal/ferromagnet nanostructures, required for applications in the\nemergent magnetic technologies like random access memories, high-frequency nano\noscillators, or bio-inspired neuromorphic computations. We study the interface\nproperties, magnetization dynamics, magnetostatic features and spin-orbit\ninteractions within the multilayer system\nTi(2)/Co(1)/Pt(0-4)/Co(1)/MgO(2)/Ti(2) (thicknesses in nanometers) patterned by\noptical lithography on micrometer-sized bars. In the investigated devices, Pt\nis used as a source of the spin current and as a non-magnetic spacer with\nvariable thickness, which enables the magnitude of the interlayer ferromagnetic\nexchange coupling to be effectively tuned. We also find the Pt\nthickness-dependent changes in magnetic anisotropies, magnetoresistance,\neffective Hall angle and, eventually, spin-orbit torque fields at interfaces.\nThe experimental findings are supported by the relevant interface\nstructure-related simulations, micromagnetic, macrospin, as well as the spin\ndrift-diffusion models. Finally, the contribution of the spin-orbital\nEdelstein-Rashba interfacial fields is also briefly discussed in the analysis.",
        "positive": "The electrical resistance of spatially varied magnetic interface. The\n  role of normal scattering: We investigate the diffusive electron transport in conductors with spatially\ninhomogeneous magnetic properties taking into account both impurity and normal\nscattering. It is found that the additional interface resistance that arises\ndue to the magnetic inhomogeneity depends essentially on their spatial\ncharacteristics. The resistance is proportional to the spin flip time in the\ncase when the magnetic properties of the conducting system vary smoothly enough\nalong the sample. It can be used to direct experimental investigation of spin\nflip processes. In the opposite case, when magnetic characteristics are varied\nsharply, the additional resistance depends essentially on the difference of\nmagnetic properties of the sides far from the interface region. The resistance\nincreases as the frequency of the electron-electron scattering increases. We\nconsider also two types of smooth interfaces: (i) between fully spin-polarized\nmagnetics and usual magnetic (or non-magnetic) conductors, and (ii) between two\nfully oppositely polarized magnetic conductors. It is shown that the interface\nresistance is very sensitive to appearing of the fully spin-polarized state\nunder the applied external field."
    },
    {
        "anchor": "Temperature dependence of Fano resonance in nanodiamonds synthesized at\n  high static pressures: Temperature dependence of Fano resonance, recently discovered in infra-red\n(IR spectra of nanodiamonds synthesized from chloroadamantane at high static\npressures, is investigated. For the first time, marked variations of the\nresonance parameteres are observed. On heating, the shape of the Fano resonance\nchanges considerably; the effect completely disappears above 350 C, but is\nrecovered after cooling to ambient conditions. Such behaviour implies that\nassignment of the Fano effect to the surface transfer doping mechanism is not\nvery plausible for the studied samples. The resonance shape varies due to\nstrong temperature dependence of the difference of frequencies of IR-active\n\"bright\" and Raman-active \"dark\" modes of nanodiamond. The frequency of the\nRaman \"dark\" mode is only weakly temperature-dependent.",
        "positive": "A critical analysis on the sensitivity enhancement of surface plasmon\n  resonance sensors with graphene: The use of graphene in surface plasmon resonance sensors, covering a metallic\n(plasmonic) film, has a number of demonstrated advantages, such protecting the\nfilm against corrosion/oxidation and facilitating the introduction of\nfunctional groups for selective sensing. Recently, a number of works have\nclaimed that few-layer graphene can also increase the sensitivity of the\nsensor. However, graphene was treated as an isotropic thin film, with an\nout-of-plane refractive index that is identical to the in-plane index. Here, we\ncritically examine the role of single and few layers of graphene in the\nsensitivity enhancement of surface plasmon resonance sensors. Graphene is\nintroduced over the metallic film via three different descriptions: as an\natomic-thick two-dimensional sheet, as a thin effective isotropic material\n(same conductivity in the three coordinate directions), and as an non-isotropic\nlayer (different conductivity in the perpendicular direction to the\ntwo-dimensional plane). We find that only the isotropic layer model, which is\nknown to be incorrect for the optically modelling of graphene, provides\nsizeable sensitivity increases, while the other, more accurate, models lead to\nnegligible contribution to the sensitivity."
    },
    {
        "anchor": "Shot Noise in Ballistic Quantum Dots with a Mixed Classical Phase Space: We investigate shot noise for quantum dots whose classical phase space\nconsists of both regular and chaotic regions. The noise is systematically\nsuppressed below the universal value of fully chaotic systems, by an amount\nwhich varies with the positions of the leads. We analyze the dynamical origin\nof this effect by a novel way to incorporate diffractive impurity scattering.\nThe dependence of the shot noise on the scattering rate shows that the\nsuppression arises due to the deterministic nature of transport through regular\nregions and along short chaotic trajectories. Shot noise can be used to probe\nphase-space structures of quantum dots with generic classical dynamics.",
        "positive": "Perspective: 3D quantum Hall effect: The discovery of the quantum Hall effect in 2D systems opens the door to\ntopological phases of matter. A quantum Hall effect in 3D is a long-sought\nphase of matter and has inspired many efforts and claims. In the perspective,\nwe review our proposal that guarantees a 3D quantum Hall effect. The proposal\nemploys the topologically-protected Fermi arcs and the \"wormhole\" tunneling via\nthe Weyl nodes in a 3D topological semimetal. The 1D edge states in this 3D\nquantum Hall effect show an example of (d-2)-dimensional boundary states.\nPossible signatures of the 3D quantum Hall effect have been observed in the\ntopological Dirac semimetals, but with many questions, which will attract more\nworks to verify the mechanism and realize the 3D quantum Hall in the future."
    },
    {
        "anchor": "D- shallow donor near a semiconductor-metal and a\n  semiconductor-dielectric interface: The ground state energy and the extend of the wavefunction of a negatively\ncharged donor (D-) located near a semiconductor-metal or a\nsemiconductor-dielectric interface is obtained. We apply the effective mass\napproximation and use a variational two-electron wavefunction that takes into\naccount the influence of all image charges that arise due to the presence of\nthe interface, as well as the correlation between the two electrons bound to\nthe donor. For a semiconductor-metal interface, the D- binding energy is\nenhanced for donor positions d>1.5a_B (a_B is the effective Bohr radius) due to\nthe additional attraction of the electrons with their images. When the donor\napproaches the interface (i.e. d<1.5a_B) the D- binding energy drops and\neventually it becomes unbound. For a semiconductor-dielectric (or a\nsemiconductor-vacuum) interface the D- binding energy is reduced for any donor\nposition as compared to the bulk case and the system becomes rapidly unbound\nwhen the donor approaches the interface.",
        "positive": "Electronic quantum optics beyond the integer quantum Hall effect: The analog of two seminal quantum optics experiments are considered in a\ncondensed matter setting with single electron sources injecting electronic wave\npackets on edge states coupled through a quantum point contact. When only one\nelectron is injected, the measurement of noise correlations at the output of\nthe quantum point contact corresponds to the Hanbury-Brown and Twiss setup.\nWhen two electrons are injected on opposite edges, the equivalent of the\nHong-Ou-Mandel collision is achieved, exhibiting a dip as in the coincidence\nmeasurements of quantum optics. The Landauer-Buttiker scattering theory is used\nto first review these phenomena in the integer quantum Hall effect, next, to\nfocus on two more exotic systems: edge states of two dimensional topological\ninsulators, where new physics emerges from time reversal symmetry and three\nelectron collisions can be achieved; and edges states of a hybrid\nHall/superconducting device, which allow to perform electron quantum optics\nexperiments with Bogoliubov quasiparticles."
    },
    {
        "anchor": "Quantum charge pumping through fractional Fermions in charge density\n  modulated quantum wires and Rashba nanowires: We study the phenomenon of adiabatic quantum charge pumping in systems\nsupporting fractionally charged fermionic bound states, in two different\nsetups. The first quantum pump setup consists of a charge-density-modulated\nquantum wire, and the second one is based on a semiconducting nanowire with\nRashba spin-orbit interaction, in the presence of a spatially oscillating\nmagnetic field. In both these quantum pumps transport is investigated in a\nN-X-N geometry, with the system of interest (X) connected to two normal-metal\nleads (N), and the two pumping parameters are the strengths of the effective\nwire-lead barriers. Pumped charge is calculated within the scattering matrix\nformalism. We show that quantum pumping in both setups provides a unique\nsignature of the presence of the fractional-fermion bound states, in terms of\nasymptotically quantized pumped charge. Furthermore, we investigate shot noise\narising due to quantum pumping, verifying that quantized pumped charge\ncorresponds to minimal shot noise.",
        "positive": "The development and applications of ultrafast electron\n  nanocrystallography: We review the development of ultrafast electron nanocrystallography as a\nmethod for investigating structural dynamics for nanoscale materials and\ninterfaces. Its sensitivity and resolution are demonstrated in the studies of\nsurface melting of gold nanocrystals, nonequilibrium transformation of graphite\ninto reversible diamond-like intermediates, and molecular scale charge\ndynamics, showing a versatility for not only determining the structures, but\nalso the charge and energy redistribution at interfaces. A quantitative scheme\nfor three-dimensional retrieval of atomic structures is demonstrated with\nfew-particle (< 1000) sensitivity, establishing this nanocrystallographic\nmethod as a tool for directly visualizing dynamics within isolated\nnanomaterials with atomic scale spatio-temporal resolution."
    },
    {
        "anchor": "Band gap engineering in AA-stacked bilayer graphene: We demonstrate that AA-stacked bilayer graphene (AA-BLG) encapsulated by\ndielectric materials can possess an energy gap due to the induced mass term.\nUsing the four-band continuum model, we evaluate transmission and reflection\nprobabilities along with the respective conductance. Considering interlayer\nmass-term difference opens a gap in the energy spectrum and also couples the\ntwo Dirac cones. This cone coupling induces an inter-cone transport that is\nasymmetric with respect to the normal incidence in the presence of asymmetric\nmass-term. The energy spectrum of the gapped AA-BLG exhibits electron-hole\nasymmetry that is reflected in the associated intra- and inter-cone channels.\nWe also find that even though Klein tunneling exists in gated and biased\nAA-BLG, it is precluded by the interlayer mass-term difference and instead\nFebry-P\\'erot resonances appear.",
        "positive": "Theory of Optical Nonlocality in Polar Dielectrics: Sub-wavelength confinement of mid-infrared light can be achieved exploiting\nthe metal-like optical response of polar dielectric crystals in their\nReststrahlen spectral region, where they support evanescent modes termed\nsurface phonon polaritons. In the past few years the investigation of phonon\npolaritons localised in nanoresonators and layered heterostructures has enjoyed\nremarkable success, highlighting them as a promising platform for mid-infrared\nnanophotonic applications. Here we prove that the standard local dielectric\ndescription of phonon polaritons in nanometric objects fails due to the\nnonlocal nature of the phonon response and we develop the corresponding\nnonlocal theory. Application of our general theory to both dielectric\nnanospheres and thin films demonstrates that polar dielectrics exhibit a rich\nnonlocal phenomenology, qualitatively different from the one of plasmonic\nsystems, due to the negative dispersion of phononic optical modes."
    },
    {
        "anchor": "Low-energy Electron Reflectivity from Graphene: Low-energy reflectivity of electrons from single- and multi-layer graphene is\nexamined both theoretically and experimentally. A series of minima in the\nreflectivity over the energy range of 0 - 8 eV are found, with the number of\nminima depending on the number of graphene layers. Using first-principles\ncomputations, it is demonstrated that a free standing n-layer graphene slab\nproduces n-1 reflectivity minima. This same result is also found experimentally\nfor graphene supported on SiO2. For graphene bonded onto other substrates it is\nargued that a similar series of reflectivity minima is expected, although in\ncertain cases an additional minimum occurs, at an energy that depends on the\ngraphene-substrate separation and the effective potential in that space.",
        "positive": "Analytical Expression for the RKKY Interaction in Doped Graphene: We obtain an analytical expression for the Ruderman-Kittel-Kasuya-Yosida\n(RKKY) interaction $J$ in electron or hole doped graphene for linear Dirac\nbands. The results agree very well with the numerical calculations for the full\ntight-binding band structure in the regime where the linear band structure is\nvalid. The analytical result, expressed in terms of the Meijer G-function,\nconsists of a product of two oscillatory terms, one coming from the\ninterference between the two Dirac cones and the second coming from the finite\nsize of the Fermi surface. For large distances, the Meijer G-function behaves\nas a sinusoidal term, leading to the result $J \\sim R^{-2} k_F \\sin (2 k_F R)\n{1 + \\cos[(K-K').R]}$ for moments located on the same sublattice. The $R^{-2}$\ndependence, which is the same for the standard two-dimensional electron gas, is\nuniversal irrespective of the sublattice location and the distance direction of\nthe two moments except when $k_F =0$ (undoped case), where it reverts to the\n$R^{-3}$ dependence. These results correct several inconsistencies found in the\nliterature."
    },
    {
        "anchor": "Generalized WKB theory for electron tunneling in gapped\n  $\u03b1-\\mathcal{T}_3$ lattices: We generalize Wentzel-Kramers-Brillouin (WKB) semi-classical equations for\npseudospin-1 $\\alpha-\\mathcal{T}_3$ materials with arbitrary hopping parameter\n$0 < \\alpha < 1$, which includes the dice lattice and graphene as two limiting\ncases. In conjunction with a series-expansion method in powers of Planck\nconstant $\\hbar$, we acquired and solved a system of recurrent differential\nequations for semi-classical electron wave functions in $\\alpha-\\mathcal{T}_3$.\nMaking use of these obtained wave functions, we analyzed the physics-related\nmechanism and quantified the transmission of pseudospin-1 Dirac electrons\nacross non-rectangular potential barriers in $\\alpha-\\mathcal{T}_3$ materials\nwith both zero and finite band gaps. Our studies reveal several unique\nfeatures, including the way in which the electron transmission depends on the\nenergy gap, the slope of the potential barrier profile and the transverse\nmomentum of incoming electrons. Specifically, we have found a strong dependence\nof the obtained transmission amplitude on the geometry-phase $\\phi = \\tan^{-1}\n\\alpha$ of $\\alpha-\\mathcal{T}_3$ lattices. We believe our current findings can\nbe applied to Dirac cone-based tunneling transistors in ultrafast analog RF\ndevices, as well as to tunneling-current control by a potential barrier through\na one-dimensional array of scatters.",
        "positive": "The VOI-Based Valleytronics: We discuss the valley-orbit interaction (VOI) and the concept of VOI based\nvalleytronics. Potential of such valleytronics is illustrated, with graphene as\nan example material, in several frontier applications comprising FETs, quantum\ncomputing, and quantum communications. Two important devices are discussed as\nexamples, namely, 1) valley pair qubits in coupled graphene quantum dots, to\nbuild quantum networks consisting of graphene and photons, and 2) valleybased\nFETs consisting of graphene quantum wires (channels) and armchair graphene\nnanoribbons (sources and drains), to build graphene-based, low-power FET\ncircuits. This demonstration makes the VOI-based valleytronics an attractive R\n& D direction in the area of electronics."
    },
    {
        "anchor": "Electron Quantization in Broken Atomic Wires: We demonstrate using scanning tunneling microscopy and spectroscopy the\nelectron quantization within metallic Au atomic wires self-assembled on a\nSi(111) surface and segmented by adatom impurities. The local electronic states\nof wire segments with a length up to 10 nm are investigated as terminated by\ntwo neighboring Si adatoms. One dimensional (1D) quantum well states are well\nresolved by their spatial distributions and the inverse-length-square\ndependence in their energies. The quantization also results in the quantum\noscillation of the conductance at the Fermi level. These results deny the\ndopant role of the adatoms assumed for a long time but indicate their strong\nscattering nature. The present approach provides a new and convenient platform\nto investigate 1D quantum phenomena with atomic precision.",
        "positive": "Composite Fermion Geometric Resonance Near \u03bd = 1/2 Fractional\n  Quantum Hall State: We observe geometric resonance features of composite fermions on the flanks\nof the even denominator {\\nu} = 1/2 fractional quantum Hall state in\nhigh-mobility two-dimensional electron and hole systems confined to wide GaAs\nquantum wells and subjected to a weak, strain-induced, unidirectional periodic\npotential modulation. The features provide a measure of how close to {\\nu} =\n1/2 the system stays single-component and supports a composite fermion Fermi\nsea before transitioning into a {\\nu} = 1/2 fractional quantum Hall state,\npresumably the two-component {\\Psi}331 state."
    },
    {
        "anchor": "Metallic supercurrent field-effect transistor: In their original formulation of superconductivity, the London brothers\npredicted the exponential suppression of an $electrostatic$ field inside a\nsuperconductor over the so-called London penetration depth, $\\lambda_L$.\nDespite a few experiments indicating hints of perturbation induced by\nelectrostatic fields, no clue has been provided so far on the possibility to\nmanipulate metallic superconductors via field-effect. Here we report\nfield-effect control of the supercurrent in $all$-metallic transistors made of\ndifferent Bardeen-Cooper-Schrieffer (BCS) superconducting thin films. At low\ntemperature, our field-effect transistors (FETs) show a monotonic decay of the\ncritical current under increasing electrostatic field up to total quenching for\ngate voltage values as large as $\\pm 40$V in titanium-based devices. This\n$bipolar$ field effect persists up to $\\sim 85\\%$ of the critical temperature\n($\\sim 0.41$K), and in the presence of sizable magnetic fields. A similar\nbehavior was observed in aluminum thin film FETs. A phenomenological theory\naccounts for our observations, and points towards the interpretation in terms\nof an electric-field-induced perturbation propagating inside the\nsuperconducting film. In our understanding, this affects the pairing potential\nand quenches the supercurrent. These results could represent a groundbreaking\nasset for the realization of an $all$-metallic superconducting field-effect\nelectronics and leading-edge quantum information architectures.",
        "positive": "Single-atom catalysts boost nitrogen electroreduction reaction: Ammonia (NH3) is mainly produced through the traditional Haber-Bosch process\nunder harsh conditions with huge energy consumption and massive carbon dioxide\n(CO2) emission. The nitrogen electroreduction reaction (NERR), as an\nenergy-efficient and environment-friendly process of converting nitrogen (N2)\nto NH3 under ambient conditions, has been regarded as a promising alternative\nto the Haber-Bosch process and has received enormous interest in recent years.\nAlthough some exciting progress has been made, considerable scientific and\ntechnical challenges still exist in improving the NH3 yield rate and Faradic\nefficiency, understanding the mechanism of the reaction and promoting the wide\ncommercialization of NERR. Single-atom catalysts (SACs) have emerged as\npromising catalysts because of its atomically dispersed activity sites and\nmaximized atom efficiency, unsaturated coordination environment, and its unique\nelectronic structure, which could significantly improve the rate of reaction\nand yield rate of NH3. In this review we briefly introduce the unique\nstructural and electronic features of SACs, which contributes to\ncomprehensively understand the reaction mechanism owing to their structural\nsimplicity and diversity, and in turn expedite the rational design of fantastic\ncatalysts at the atomic scale. Then, we summarize the most recent experimental\nand computational efforts on developing novel SACs with excellent NERR\nperformance, including precious metal-, nonprecious metal- and nonmetal-based\nSACs. Finally, we present challenges and perspectives of SACs on NERR, as well\nas some potential means for advanced NERR catalyst."
    },
    {
        "anchor": "Is there a d.c. Josephson Effect in Bilayer Quantum Hall Systems?: We argue on the basis of phenomenological and microscopic considerations that\nthere is no d.c. Josephson effect in ordered bilayer quantum Hall systems, even\nat T=0. Instead the tunnel conductance is strongly enhanced, approaching a\nfinite value proportional to the square of the order parameter as the\ninterlayer tunneling amplitude vanishes.",
        "positive": "Nonlinear Hall Acceleration and the Quantum Rectification Sum Rule: Electrons moving in a Bloch band are known to acquire an anomalous Hall\nvelocity proportional to the Berry curvature of the band which is responsible\nfor the intrinsic linear Hall effect in materials with broken time-reversal\nsymmetry. Here, we demonstrate that there is also an anomalous correction to\nthe electron acceleration which is proportional to the Berry curvature dipole\nand is responsible for the Nonlinear Hall effect recently discovered in\nmaterials with broken inversion symmetry. This allows us to uncover a deeper\nmeaning of the Berry curvature dipole as a nonlinear version of the Drude\nweight that serves as a measurable order parameter for broken inversion\nsymmetry in metals. We also derive a quantum rectification sum rule in time\nreversal invariant materials by showing that the integral over frequency of the\nrectification conductivity depends solely on the Berry connection and not on\nthe band energies. The intraband spectral weight of this sum rule is exhausted\nby the Berry curvature dipole Drude-like peak, and the interband weight is also\nentirely controlled by the Berry connection. This sum rule opens a door to\nsearch for alternative photovoltaic technologies based on the Berry geometry of\nbands. We also describe the rectification properties of Weyl semimetals which\nare a promising platform to investigate these effects."
    },
    {
        "anchor": "Excitons in quantum dot molecules: Coulomb coupling, spin-orbit effects\n  and phonon-induced line broadening: Excitonic states and the line shape of optical transitions in coupled quantum\ndots (quantum dot molecules) are studied theoretically. For a pair of\nelectrically tunable, vertically aligned quantum dots we investigate the\ncoupling between spatially direct and indirect excitons caused by different\nmechanisms such as tunnel coupling, Coulomb coupling, coupling due to the\nspin-orbit interaction and coupling induced by a structural asymmetry. The\npeculiarities of the different types of couplings are reflected in the\nappearance of either crossings or avoided crossings between direct and indirect\nexcitons, the latter ones being directly visible in the absorption spectrum. We\nanalyze the influence of the phonon environment on the spectrum by calculating\nthe line shape of the various optical transitions including contributions due\nto both pure dephasing and phonon-induced transitions between different exciton\nstates. The line width enhancement due to phonon-induced transitions is\nparticularly pronounced in the region of an anticrossing and it strongly\ndepends on the energy splitting between the two exciton branches.",
        "positive": "Quantum Hall quasielectrons - Abelian and non-Abelian: The quasiparticles in Quantum Hall liquids carry fractional charge and obey\nfractional quantum statistics. Of particular recent interest are those with\nnon-Abelian statistics, since their braiding properties could in principle be\nused for robust coding of quantum information. There is already a good\ntheoretical understanding of quasiholes both in Abelian and non-Abelian QH\nstates. Here we develop conformal field theory methods that allow for an\nequally precise description of quasielectrons, and explicitly construct two-\nand four-quasielectron excitations of the non-Abelian Moore-Read state."
    },
    {
        "anchor": "Rashba quantum wire: exact solution and ballistic transport: The effect of Rashba spin-orbit interaction in quantum wires with hard-wall\nboundaries is discussed. The exact wave function and eigenvalue equation are\nworked out pointing out the mixing between the spin and spatial parts. The\nspectral properties are also studied within the perturbation theory with\nrespect to the strength of the spin-orbit interaction and diagonalization\nprocedure. A comparison is done with the results of a simple model, the\ntwo-band model, that takes account only of the first two sub-bands of the wire.\nFinally, the transport properties within the ballistic regime are analytically\ncalculated for the two-band model and through a tight-binding Green function\nfor the entire system. Single and double interfaces separating regions with\ndifferent strengths of spin-orbit interaction are analyzed injecting carriers\ninto the first and the second sub-band. It is shown that in the case of a\nsingle interface the spin polarization in the Rashba region is different from\nzero, and in the case of two interfaces the spin polarization shows\noscillations due to spin selective bound states.",
        "positive": "Single- and few-electron dynamic quantum dots in a perpendicular\n  magnetic field: We present experimental studies of the current pumped through a dynamic\nquantum dot over a wide range of magnetic fields. At low fields we observe\nrepeatable structure indicating increased confinement of the electrons in the\ndynamic dot. At higher fields (B>3T), we observe structure which changes\nmarkedly from device to device suggesting that in this regime the transport is\nsensitive to local disorder. The results are significant for the development of\ndynamic quantum dot pumps as quantum standards of electrical current."
    },
    {
        "anchor": "The effect of (NH4)2Sx passivation on the (311)A GaAs surface and its\n  use in AlGaAs/GaAs heterostructure devices: We have studied the efficacy of (NH4)2Sx surface passivation on the (311)A\nGaAs surface. We report XPS studies of simultaneously-grown (311)A and (100)\nheterostructures showing that the (NH4)2Sx solution removes surface oxide and\nsulfidizes both surfaces. Passivation is often characterized using\nphotoluminescence measurements, we show that while (NH4)2Sx treatment gives a\n40 - 60 x increase in photoluminescence intensity for the (100) surface, an\nincrease of only 2 - 3 x is obtained for the (311)A surface. A corresponding\nlack of reproducible improvement in the gate hysteresis of (311)A\nheterostructure transistor devices made with the passivation treatment\nperformed immediately prior to gate deposition is also found. We discuss\npossible reasons why sulfur passivation is ineffective for (311)A GaAs, and\npropose alternative strategies for passivation of this surface.",
        "positive": "Disordered contacts can localize chiral edge electrons: Chiral integer quantum Hall (QH) edge modes are immune to backscattering and\ntherefore are non-localized and show a vanishing longitudinal as well as\nnon-local resistance along with quantized 2-terminal and Hall resistance even\nin the presence of sample disorder. However, this is not the case for contact\ndisorder, which refers to the possibility that a contact can reflect edge modes\neither partially or fully. This paper shows that when all contacts are\ndisordered in a N-terminal quantum Hall bar, then transport via chiral QH edge\nmodes can have a significant localization correction. The Hall and 2-terminal\nresistance in an N-terminal quantum Hall sample deviate from their values\nderived while neglecting the phase acquired at disordered contacts, and this\ndeviation is called the quantum localization correction. This correction term\nincreases with the increase of disorderedness of contacts but decreases with\nthe increase in the number of contacts in an N-terminal Hall bar. The presence\nof inelastic scattering, however, can completely destroy the quantum\nlocalization correction."
    },
    {
        "anchor": "Anisotropic Acoustic Plasmons in Black Phosphorus: Recently, it was demonstrated that a graphene/dielectric/metal configuration\ncan support acoustic plasmons, which exhibit extreme plasmon confinement an\norder of magnitude higher than that of conventional graphene plasmons. Here, we\ninvestigate acoustic plasmons supported in a monolayer and multilayers of black\nphosphorus (BP) placed just a few nanometers above a conducting plate. In the\npresence of a conducting plate, the acoustic plasmon dispersion for the\narmchair direction is found to exhibit the characteristic linear scaling in the\nmid- and far-infrared regime while it largely deviates from that in the long\nwavelength limit and near-infrared regime. For the zigzag direction, such\nscaling behavior is not evident due to relatively tighter plasmon confinement.\nFurther, we demonstrate a new design for an acoustic plasmon resonator that\nexhibits higher plasmon confinement and resonance efficiency than BP ribbon\nresonators in the mid-infrared and longer wavelength regime. Theoretical\nframework and new resonator design studied here provide a practical route\ntoward the experimental verification of the acoustic plasmons in BP and open up\nthe possibility to develop novel plasmonic and optoelectronic devices that can\nleverage its strong in-plane anisotropy and thickness-dependent band gap.",
        "positive": "Suppression of Surface-Originated Gate-Lag by a Dual-Channel AlN/GaN\n  HEMT Architecture: A dual-channel AlN/GaN high electron mobility transistor (HEMT) architecture\nis demonstrated that leverages ultra-thin epitaxial layers to suppress\nsurface-state related gate lag. Two high-density two-dimensional electron gas\n(2DEG) channels are utilized in an AlN/GaN/AlN/GaN heterostructure wherein the\ntop 2DEG serves as a quasi-equipotential that screens potential fluctuations\nresulting from surface and interface trapped charge. The bottom channel serves\nas the transistor's modulated channel. Dual-channel AlN/GaN heterostructures\nwere grown by molecular beam epitaxy on free-standing HVPE GaN substrates where\n300 nm long recessed and non-recessed gate HEMTs were fabricated. The\nrecessed-gate HEMT demonstrated a gate lag ratio (GLR) of 0.88 with no collapse\nin drain current and supporting small signal metrics $f_t/f_{max}$ of 27/46\nGHz. These performance results are contrasted with the non-recessed gate\ndual-channel HEMT with a GLR of 0.74 and 82 mA/mm current collapse with\n$f_t/f_{max}$ of 48/60 GHz."
    },
    {
        "anchor": "Thermoelectric transport properties of a T-shaped double quantum dot\n  system in the Coulomb blockade regime: We investigate the thermoelectric properties of a T-shaped double quantum dot\nsystem described by a generalized Anderson Hamiltonian. The system's electrical\nconduction (G) and the fundamental thermoelectric parameters such as the\nSeebeck coefficient ($S$) and the thermal conductivity ($\\kappa$), along with\nthe system's thermoelectric figure of merit (ZT) are numerically estimated\nbased on a Green's function formalism that includes contributions up to the\nHartree-Fock level. Our results account for finite onsite Coulomb interaction\nterms in both component quantum dots and discuss various ways leading to an\nenhanced thermoelectric figure of merit for the system. We demonstrate that the\npresence of Fano resonances in the Coulomb blockade regime is responsible for a\nstrong violation of the Wiedemann-Franz law and a considerable enhancement of\nthe system's figure of merit ($ZT$).",
        "positive": "Storing quantum information for 30 seconds in a nanoelectronic device: The spin of an electron or a nucleus in a semiconductor [1] naturally\nimplements the unit of quantum information -- the qubit -- while providing a\ntechnological link to the established electronics industry [2]. The solid-state\nenvironment, however, may provide deleterious interactions between the qubit\nand the nuclear spins of surrounding atoms [3], or charge and spin fluctuators\nin defects, oxides and interfaces [4]. For group IV materials such as silicon,\nenrichment of the spin-zero 28-Si isotope drastically reduces spin-bath\ndecoherence [5]. Experiments on bulk spin ensembles in 28-Si crystals have\nindeed demonstrated extraordinary coherence times [6-8]. However, it remained\nunclear whether these would persist at the single-spin level, in gated\nnanostructures near amorphous interfaces. Here we present the coherent\noperation of individual 31-P electron and nuclear spin qubits in a top-gated\nnanostructure, fabricated on an isotopically engineered 28-Si substrate. We\nreport new benchmarks for coherence time (> 30 seconds) and control fidelity (>\n99.99%) of any single qubit in solid state, and perform a detailed noise\nspectroscopy [9] to demonstrate that -- contrary to widespread belief -- the\ncoherence is not limited by the proximity to an interface. Our results\nrepresent a fundamental advance in control and understanding of spin qubits in\nnanostructures."
    },
    {
        "anchor": "Spin-photovoltaic effect in quantum wires due to inter-subband\n  transitions: We consider the current induced in a quantum wire by external electromagnetic\nradiation. The photocurrent is caused by the interplay of spin-orbit\ninteraction (Rashba and Dresselhaus terms) and external in-plane magnetic\nfield. We calculate this current using a Wigner functions approach taking into\naccount radiation-induced transitions between transverse subbands. The\nmagnitude and the direction of the current depend on the Dresselhaus and Rashba\nconstants, strength of magnetic field, radiation frequency and intensity. The\ncurrent can be controlled by changing some of these parameters.",
        "positive": "Robustness of Half-Integer Quantized Hall Conductivity against Disorder\n  in an Anisotropic Dirac Semimetal with Parity Anomaly: Two-dimensional Dirac semimetals with a single massless Dirac cone exhibit\nthe parity anomaly. Usually, such a kind of anomalous topological semimetallic\nphase in real materials is unstable where any amount of disorder can drive it\ninto a diffusive metal and destroy the half-integer quantized Hall conductivity\nas an indicator of parity anomaly. Here, based on low-energy effective model,\nwe propose an anisotropic Dirac semimetal which explicitly breaks time-reversal\nsymmetry and carries a half-integer quantized Hall conductivity. This\ntopological semimetallic phase can be realized on a deformed honeycomb lattice\nsubjected to a magnetic flux. Moreover, we perceptively investigate the\ndisorder correction to the Hall conductivity. The results show that the effects\nof disorder can be strongly suppressed and thereby the nearly half-integer\nquantization of Hall conductivity can exist in a wide region of disorder,\nindicating that our proposed anisotropic Dirac semimetal is an exciting\nplatform to investigate the parity anomaly phenomena."
    },
    {
        "anchor": "Unconventional spin texture of a topologically nontrivial semimetal\n  Sb(110): The surfaces of antimony are characterized by the presence of spin-split\nstates within the projected bulk band gap and the Fermi contour is thus\nexpected to exhibit a spin texture. Using spin-resolved density functional\ntheory calculations, we determine the spin polarization of the surface bands of\nSb(110). The existence of the unconventional spin texture is corroborated by\nthe investigations of the electron scattering on this surface. The charge\ninterference patterns formed around single scattering impurities, imaged by\nscanning tunneling microscopy, reveal the absence of direct backscattering\nsignal. We identify the allowed scattering vectors and analyze their bias\nevolution in relation to the surface-state dispersion.",
        "positive": "Transition magnon modes in thin ferromagnetic nanogratings: This work presents micromagnetic simulations in ferromagnetic nanogratings\nfor the full range of directions of an applied in-plane external magnetic\nfield. We focus on the modification of the magnon mode characteristics when the\nmagnetic field orientation is gradually changed between the classical\nDamon-Eshbach (DE) and backward-volume (BV) geometries. We found that in a\nspecific range of field directions, the magnon mode parameters differ\nsignificantly from the parameters in the classical cases, namely, the modes are\ncharacterized by complex spatial distributions and have low group velocities.\nThe center of this range corresponds to the direction of the external magnetic\nfield, which gives the maximal nonuniform distribution of the static\nmagnetization in the nanogratings."
    },
    {
        "anchor": "Andreev reflection through Fano resonances in molecular wires: We study Andreev reflection in a normal conductor-molecule-superconductor\njunction using a first principles approach. In particular, we focus on a family\nof molecules consisting of a molecular backbone and a weakly coupled side\ngroup. We show that the presence of the side group can lead to a Fano resonance\nin the Andreev reflection. We use a simple theoretical model to explain the\nresults of the numerical calculations and to make predictions about the\npossible sub-gap resonance structures in the Andreev reflection coefficient.",
        "positive": "Current-induced vortex displacement and annihilation in a single\n  Permalloy disk: The induced motion of a magnetic vortex in a micron-sized ferromagnetic disk\ndue to the DC current injection is studied by measuring planar Hall effect. The\nDC current injection is found to induce the spin torque that sweeps the vortex\nout of the disk at the critical current while bias magnetic field are applied.\nThe current-induced vortex core displacement deduced from the change in planar\nHall resistance is quantitatively consistent with theoretical prediction. Peak\nstructures similar to those originated from spin wave excitations are observed\nin the differential planar Hall resistance curve."
    },
    {
        "anchor": "Edge state transmission, duality relation and its implication to\n  measurements: The duality in the Chalker-Coddington network model is examined. We are able\nto write down a duality relation for the edge state transmission coefficient,\nbut only for a specific symmetric Hall geometry. Looking for broader\nimplication of the duality, we calculate the transmission coefficient $T$ in\nterms of the conductivity $\\sigma_{xx}$ and $\\sigma_{xy}$ in the diffusive\nlimit. The edge state scattering problem is reduced to solving the diffusion\nequation with two boundary conditions\n$(\\partial_y-(\\sigma_{xy})/(\\sigma_{xx})\\partial_x)\\phi=0$ and\n$[\\partial_x+(\\sigma_{xy}-\\sigma_{xy}^{lead})/(\\sigma_{xx}) \\partial_y]\\phi=0$.\nWe find that the resistances in the geometry considered are not necessarily\nmeasures of the resistivity and $\\rho_{xx}=L/W R/T h/e^2$ ($R=1-T$) holds only\nwhen $\\rho_{xy}$ is quantized. We conclude that duality alone is not sufficient\nto explain the experimental findings of Shahar et al and that Landauer-Buttiker\nargument does not render the additional condition, contrary to previous\nexpectation.",
        "positive": "Field Theory for Magnetic Monopoles in (Square, Artificial) Spin Ice: Proceeding from the more general to the more concrete, we propose an\nequilibrium field theory describing spin ice systems in terms of topological\ncharges and magnetic monopoles. We show that for a spin ice on a graph, the\nentropic interaction in a Gaussian approximation is the inverse of the graph\nLaplacian matrix, while the screening function for external charges is the\ninverse of the screened laplacian. We particularize the treatment to square and\npyrochlore ice. For square ice we highlight the gauge-free duality between\ndirect and perpendicular structure in terms of symmetry between charges and\ncurrents, typical of magnetic fragmentation in a two-dimensional setting. We\nderive structure factors, correlations, correlation lengths, and\nsusceptibilities for spins, topological charges, and currents. We show that the\ndivergence of the correlation length at low temperature is exponential and\ninversely proportional to the mean square charge. While in three dimension real\nand entropic interactions among monopoles are both 3D-Coulomb, in two dimension\nthe former is a 3D-Coulomb and the latter 2D-Coulomb, or logarithmic, leading\nto weak singularities in correspondence of the pinch points and destroying\ncharge screening. This suggests that the monopole plasma of square ice is a\nmagnetic charge insulator."
    },
    {
        "anchor": "Dynamical calculation of third harmonic generation in a semiconductor\n  quantum well: Non-linear phenomena in optically excited semiconductor structures are of\nhigh interest. We here develop a model capable of studying the dynamics of the\nphotoexcited carriers, including Coulomb interaction on a Hartree-Fock level,\non the same footing as the dynamics of the light field impinging on an\narbitrary photonic structure. Applying this method to calculate the third\nharmonic generation in a semiconductor quantum well embedded in a Bragg mirror\nstructure, we find that the power-law exponent of the intensity dependence of\nthe third harmonic generation depends on the frequency of the exciting pulse.\nOff-resonant pulses follow the expected cubic dependence, while the exponent is\nsmaller for resonant pulses due to saturation effects in the induced carrier\ndensity. Our study provides a detailed understanding of the carrier and light\nfield dynamics during non-linear processes.",
        "positive": "Unconventional localisation transition in high dimensions: We study non-interacting systems with a power-law quasiparticle dispersion\n$\\xi_{\\bf k}\\propto k^\\alpha$ and a random short-range-correlated potential. We\nshow that, unlike the case of lower dimensions, for $d>2\\alpha$ there exists a\ncritical disorder strength (set by the band width), at which the system\nexhibits a disorder-driven quantum phase transition at the bottom of the band,\nthat lies in a universality class distinct from the Anderson transition. In\ncontrast to the conventional wisdom, it manifests itself in, e.g., the\ndisorder-averaged density of states. For systems in symmetry classes that\npermit localisation, the striking signature of this transition is a\nnon-analytic behaviour of the mobility edge, that is pinned to the bottom of\nthe band for subcritical disorder and grows for disorder exceeding a critical\nstrength. Focussing on the density of states, we calculate the critical\nbehaviour (exponents and scaling functions) at this novel transition, using a\nrenormalisation group, controlled by an $\\varepsilon=2\\alpha-d$ expansion. We\nalso apply our analysis to Dirac materials, e.g., Weyl semimetal, where this\ntransition takes place in physically interesting three dimensions."
    },
    {
        "anchor": "Combined effect of mutually frequency-detuned strong and weak drives on\n  a two-level system: Envelope of the Rabi oscillations: Near-resonant ac-drive acting on a two-level system induces the Rabi\noscillations of the level occupations. It is shown that additional weak drive\nproperly frequency-detuned from the primary drive causes a resonant response.\nThis response manifests itself in the emergence of the envelope of the\noscillations. At resonance, the inverse period of the envelope is proportional\nto the amplitude of the weak drive. The resonant condition reads: difference of\nfrequencies between the two drives is equal to the ac-splitting of quasilevels\nin the field of the strong drive. Technically, the resonance can be inferred\nfrom the analogy between the equations for the time-evolution of the spin\namplitude and the Mathieu equation, which describes e.g. the parametric\nresonance.",
        "positive": "Configure polaritons in twisted $\u03b1$-MoO3: Moire engineering as a configuration method to twist van der Waals materials\nhas delivered a series of advances in electronics, magnetics and optics. Yet\nthese advances stem from peculiar moire superlattices which form at small\nspecific twisting angles. Here we report the configuration of nanoscale\nlight-matter waves-the polaritons-by twisting stacked $\\alpha$-phase molybdenum\ntrioxide $\\alpha$-MoO3 slabs in the broad range of 0$^o$ to 90$^o$. Our\ncombined experimental and theoretical results reveal a variety of polariton\nwavefront geometry and topological transitions via the twisting. The polariton\ntwisting configuration is attributed to the electromagnetic interaction of\nhighly anisotropic hyperbolic polaritons in stacked $\\alpha$-MoO3 slabs. The\nnano-polaritons demonstrated in twisted $\\alpha$-MoO3 hold the promise as\ntailored nano-light for on-demand nanophotonic functionalities."
    },
    {
        "anchor": "Confinement of long-lived interlayer excitons in WS$_2$/WSe$_2$\n  heterostructures: Interlayer excitons in layered materials constitute a novel platform to study\nmany-body phenomena arising from long-range interactions between quantum\nparticles. The ability to localise individual interlayer excitons in potential\nenergy traps is a key step towards simulating Hubbard physics in artificial\nlattices. Here, we demonstrate spatial localisation of long-lived interlayer\nexcitons in a strongly confining trap array using a WS$_{2}$/WSe$_{2}$\nheterostructure on a nanopatterned substrate. We detect long-lived interlayer\nexcitons with lifetime approaching 0.2 ms and show that their confinement\nresults in a reduced lifetime in the microsecond range and stronger emission\nrate with sustained optical selection rules. The combination of a permanent\ndipole moment, spatial confinement and long lifetime places interlayer excitons\nin a regime that satisfies one of the requirements for observing long-range\ndynamics in an optically resolvable trap lattice.",
        "positive": "Effective Mass and Spin Susceptibility of Dilute Two-Dimensional Holes\n  in GaAs: We report effective hole mass ($m^{*}$) measurements through analyzing the\ntemperature dependence of Shubnikov-de Haas oscillations in dilute (density $p\n\\sim 7 \\times 10^{10}$ cm$^{-2}$, $r_{s} \\sim 6$) two-dimensional (2D) hole\nsystems confined to a 20 nm-wide, (311)A GaAs quantum well. The holes in this\nsystem occupy two nearly-degenerate spin subbands whose $m^{*}$ we measure to\nbe $\\sim $ 0.2 (in units of the free electron mass). Despite the relatively\nlarge $r_{s}$ in our 2D system, the measured $m^{*}$ is in good agreement with\nthe results of our energy band calculations which do not take interactions into\naccount. We hen apply a sufficiently strong parallel magnetic field to fully\ndepopulate one of the spin subbands, and measure $m^{*}$ for the populated\nsubband. We find that this latter $m^{*}$ is surprisingly close to the $m^{*}$\nwe measure in the absence of the parallel field. We also deduce the spin\nsusceptibility of the 2D hole system from the depopulation field, and conclude\nthat the susceptibility is enhanced by about 50% relative to the value expected\nfrom the band calculations."
    },
    {
        "anchor": "Gate tuning from exciton superfluid to quantum anomalous Hall in van der\n  Waals heterobilayer: Van der Waals heterostructures of 2D materials provide a powerful approach\ntowards engineering various quantum phases of matters. Examples include\ntopological matters such as quantum spin Hall (QSH) insulator, and correlated\nmatters such as exciton superfluid. It can be of great interest to realize\nthese vastly different quantum matters on a common platform, however, their\ndistinct origins tend to restrict them to material systems of incompatible\ncharacters. Here we show that heterobilayers of two-dimensional valley\nsemiconductors can be tuned through interlayer bias between an exciton\nsuperfluid (ES), a quantum anomalous Hall (QAH) insulator, and a QSH insulator.\nThe tunability between these distinct phases results from the competition of\nCoulomb interaction with the interlayer quantum tunnelling that has a chiral\nform in valley semiconductors. Our findings point to exciting opportunities for\nharnessing both protected topological edge channels and bulk superfluidity in\nan electrically configurable platform.",
        "positive": "Unveiling hidden topological phases of a one-dimensional Hadamard\n  quantum walk: Quantum walks, whose dynamics is prescribed by alternating unitary coin and\nshift operators, possess topological phases akin to those of Floquet\ntopological insulators, driven by a time-periodic field. While there is ample\ntheoretical work on topological phases of quantum walks where the coin\noperators are spin rotations, in experiments a different coin, the Hadamard\noperator is often used instead. This was the case in a recent photonic quantum\nwalk experiment, where protected edge states were observed between two bulks\nwhose topological invariants, as calculated by the standard theory, were the\nsame. This hints at a hidden topological invariant in the Hadamard quantum\nwalk. We establish a relation between the Hadamard and the spin rotation\noperator, which allows us to apply the recently developed theory of topological\nphases of quantum walks to the one-dimensional Hadamard quantum walk. The\ntopological invariants we derive account for the edge state observed in the\nexperiment, we thus reveal the hidden topological invariant of the\none-dimensional Hadamard quantum walk."
    },
    {
        "anchor": "Magnetization of two coupled rings: We investigate the persistent currents and magnetization of a mesoscopic\nsystem consisting of two clean metallic rings sharing a single contact point in\na magnetic field. Many novel features with respect to the single-ring geometry\nare underlined, including the explicit dependence of wavefunctions on the\nAharonov-Bohm fluxes, the complex pattern of twofold and threefold\ndegeneracies, the key role of length and flux commensurability, and in the case\nof commensurate ring lengths the occurrence of idle levels which do not carry\nany current. Spin-orbit interactions, induced by the electric fields of charged\nwires threading the rings, give rise to a peculiar version of the\nAharonov-Casher effect where, unlike for a single ring, spin is not conserved.\nRemarkably enough, this can only be realized when the Aharonov-Bohm fluxes in\nboth rings are neither integer nor half-integer multiples of the flux quantum.",
        "positive": "The Fractional Quantum Hall States of Dirac Electrons in Graphene: We have investigated the fractional quantum Hall states for the Dirac\nelectrons in a graphene layer in different Landau levels. The relativistic\nnature of the energy dispersion relation of the electrons in the graphene\nsignificantly modifies the inter-electron interactions. This results in a\nspecific dependence of the ground state energy and the energy gaps for\nelectrons on the Landau level index. For the valley-polarized states, i.e. at\n\\nu =1/m, m being an odd integer, the energy gaps have the largest values in\nthe n=1 Landau level. For the valley-unpolarized states, e.g., for the 2/3\nstate, the energy gaps are suppressed for the n=1 Landau level as compared to\nthe n=0 level. For both the n=1 and n=0 Landau levels the ground state of the\n2/3 system is fully valley-unpolarized."
    },
    {
        "anchor": "Measurement of the complete interaction force curve at the nanoscale: The force between two interacting particles as a function of distance is one\nof the most fundamental curves in science. In this regard, Atomic Force\nMicroscopy (AFM) represents the most powerful tool in nanoscience but with\nsevere limits when it is to probe attractive interactions with high\nsensitivity. The Force Feedback Microscope (FFM) described here, removes from\nAFM the well known jump to contact problem that precludes the complete\nexploration of the interaction curve and the study of associated energy\nexchanges. The FFM makes it possible to explore tip-surface interactions in the\nentire range of distances with a sensitivity better than 1 pN. FFM stands out\nas a radical change in AFM control paradigms. With a surprisingly simple\narrangement it is possible to provide the AFM tip with the right counterforce\nto keep it fixed at any time. The counterforce is consequently equal to the\ntip-sample force. The force, force gradient and damping are simultaneously\nmeasured independently of the tip position. This permits the measurement of\nenergy transfer in thermodynamic transformations. Here we show some FFM\nmeasurement examples of the complete interaction force curve and in particular\nthat the FFM can follow the nucleation of a water bridge by measuring the\ncapillary attractive force at all distances, without jump to contact despite\nthe large attractive capillary force. Real time combination of the measured\nparameters will lead to new imaging modalities with chemical contrast in\ndifferent environments.",
        "positive": "H$_2$ dissociation over Au-nanowires and the fractional conductance\n  quantum: The dissociation of H$_2$ molecules on stretched Au nanowires and its effect\non the nanowire conductance are analyzed using a combination of Density\nFunctional (DFT) total energy calculations and non-equilibrium Keldish-Green\nfunction methods. Our DFT simulations reproduce the characteristic formation of\nAu monoatomic chains with a conductance close to % the conductance quantum $G_0\n= 2e^2/h$. These stretched Au nanowires are shown to be better catalysts for\nH$_2$ dissociation than Au surfaces. This is confirmed by the nanowire\nconductance evidence: while not affected practically by molecular hydrogen,\natomic hydrogen induces the appearance of fractional conductances ($G \\sim 0.5\nG_0$) as observed experimentally."
    },
    {
        "anchor": "Ultra-compact injection terahertz laser using the resonant inter-layer\n  radiative transitions in multi-graphene-layer structure: The optimization of laser resonators represents a crucial issue for the\ndesign of terahertz semiconductor lasers with high gain and low absorption\nloss. In this paper, we put forward and optimize the surface plasmonic metal\nwaveguide geometry for the recently proposed terahertz injection laser based on\nresonant radiative transitions between tunnel-coupled grapheme layers. We find\nan optimal number of active graphene layer pairs corresponding to the maximum\nnet modal gain. The maximum gain increases with frequency and can be as large\nas ~ 500 cm-1 at 8 THz, while the threshold length of laser resonator can be as\nsmall as ~ 50 mkm. Our findings substantiate the possibility of ultra-compact\nvoltage-tunable graphene-based lasers operating at room temperature.",
        "positive": "An open-source platform to study uniaxial stress effects on nanoscale\n  devices: We present an automatic measurement platform that enables the\ncharacterization of nanodevices by electrical transport and optical\nspectroscopy as a function of uniaxial stress. We provide insights into and\ndetailed descriptions of the mechanical device, the substrate design and\nfabrication, and the instrument control software, which is provided under\nopen-source license. The capability of the platform is demonstrated by\ncharacterizing the piezo-resistance of an InAs nanowire device using a\ncombination of electrical transport and Raman spectroscopy. The advantages of\nthis measurement platform are highlighted by comparison with state-of-the-art\npiezo-resistance measurements in InAs nanowires. We envision that the\nsystematic application of this methodology will provide new insights into the\nphysics of nanoscale devices and novel materials for electronics, and thus\ncontribute to the assessment of the potential of strain as a technology booster\nfor nanoscale electronics."
    },
    {
        "anchor": "Electronic and Vibrational Properties of PbI 2 : From Bulk to Monolayer: Using first-principles calculations, we study the dependence of the\nelectronic and vibrational properties of multi-layered PbI 2 crystals on the\nnumber of layers and focus on the electronic-band structure and the Raman\nspectrum. Electronic-band structure calculations reveal that the direct or\nindirect semiconducting behavior of PbI 2 is strongly influenced by the number\nof layers. We find that at 3L-thickness there is a direct-to-indirect band gap\ntransition (from bulk-to-monolayer). It is shown that in the Raman spectrum two\nprominent peaks, A 1g and E g , exhibit phonon hardening with increasing number\nof layers due to the inter-layer van der Waals interaction. Moreover, the Raman\nactivity of the A 1g mode significantly increases with increasing number of\nlayers due to the enhanced out-of-plane dielectric constant in the few-layer\ncase. We further characterize rigid-layer vibrations of low-frequency\ninter-layer shear (C) and breathing (LB) modes in few-layer PbI 2 . A reduced\nmono-atomic (linear) chain model (LCM) provides a fairly accurate picture of\nthe number of layers dependence of the low-frequency modes and it is shown also\nto be a powerful tool to study the inter-layer coupling strength in layered PbI\n2 .",
        "positive": "Electron-electron interaction effects in quantum point contacts: We consider electron-electron interaction effects in quantum point contacts\non the first quantization plateau, taking into account all scattering\nprocesses. We compute the low-temperature linear and nonlinear conductance,\nshot noise, and thermopower, by perturbation theory and a self-consistent\nnonperturbative method. On the conductance plateau, the low-temperature\ncorrections are solely due to momentum-nonconserving processes that change the\nrelative number of left- and right-moving electrons. This leads to a\nsuppression of the conductance for increasing temperature or voltage. The size\nof the suppression is estimated for a realistic saddle-point potential, and is\nlargest in the beginning of the conductance plateau. For large magnetic field,\ninteraction effects are strongly suppressed by the Pauli principle, and hence\nthe first spin-split conductance plateau has a much weaker interaction\ncorrection. For the nonperturbative calculations, we use a self-consistent\nnonequilibrium Green's function approach, which suggests that the conductance\nsaturates at elevated temperatures. These results are consistent with many\nexperimental observations related to the so-called 0.7 anomaly."
    },
    {
        "anchor": "Collective modes of quantum dot ensembles in microcavities: Emission spectra of quantum dot arrays in zero-dimensional microcavities are\nstudied theoretically, and it is shown that they are determined by the\ncompetition between the formation of the collective superradiant mode and\ninhomogeneous broadening. The random sources method for the calculation of\nphotoluminescence spectra under a non-resonant pumping is developed, and a\nmicroscopic justification of the random sources method within a framework of\nthe standard diagram technique is given. The emission spectra of a microcavity\nare analyzed with allowance for the spread of exciton states energies caused by\nan inhomogeneous distribution of quantum dots and a tunneling between them. It\nis demonstrated that in the case of a strong tunneling coupling the\nluminescence spectra are sensitive to the geometric positions of the dots, and\nthe collective mode can, under certain conditions, be stabilized by the random\ntunnel junctions.",
        "positive": "Partial time-reversal invariance violation in a flat, superconducting\n  microwave cavity with the shape of a chaotic Africa billiard: We report on the experimental realization of a flat, superconducting\nmicrowave resonator, a microwave billiard, with partially violated\ntime-reversal (T ) invariance, induced by inserting a ferrite into the cavity\nand magnetizing it with an external magnetic field perpendicular to the\nresonator plane. In order to prevent its expulsion caused by the\nMeissner-Ochsenfeld effect we used a cavity of which the top and bottom plate\nwere made from niobium, a superconductor of type II, and cooled it down to\nliquid-helium temperature T LHe ' 4 K. The Cavity had the shape of a chaotic\nAfrivca billiard. Superconductivity rendered possible the accurate\ndetermination of complete sequences of the resonance frequencies and of the\nwidths and strengths of the resonances, an indispensable prerequisite for the\nunambiguous detection of T invariance violation, especially when it is only\npartially violated. This allows for the first time the precise specification of\nthe size of T invariance violation from the fluctuation properties of the\nresonance frequencies and from the strength distribution, which actually\ndepends sensitively on it and thus provides a most suitable measure. For this\npurpose we derived an analytical expression for the latter which is valid for\nisolated resonances in the range from no T invariance violation to complete\nviolation."
    },
    {
        "anchor": "Majorana bound state in the continuum: Coupling between Majorana bound\n  state and quantum dot mediated by continuum: In this work, we consider a single-level quantum dot (QD) and a Majorana\nbound state (MBS) placed at the end of a topological superconducting nanowire\n(TSW). Both are coupled to the continuum and do not have a direct connection\nbetween them. We addressed the behavior of MBS leaking phenomena and its\nconsequences into the QD physics in non-interacting and Coulomb blockade\nregime. By employing Green's function formalism via the equation of motion\nprocedure, we calculate the physical quantities of interest. Our results show\nthat the leakage of the MBS into the continuum state is achieved and can alter\nthe physics of Coulomb blockade in the system through continuum-mediated\ncoupling between MBS and QD. As a main consequence, we found a robust and\nnon-trivial mechanism to accomplish a bound state in the continuum in the\nsystem.",
        "positive": "Unified description of inelastic propensity rules for electron transport\n  through nanoscale junctions: We present a method to analyze the results of first-principles based\ncalculations of electronic currents including inelastic electron-phonon\neffects. This method allows us to determine the electronic and vibrational\nsymmeties in play, and hence to obtain the so-called propensity rules for the\nstudied systems. We show that only a few scattering states -- namely those\nbelonging to the most transmitting eigenchannels -- need to be considered for a\ncomplete description of the electron transport. We apply the method on\nfirst-principles calculations of four different systems and obtain the\npropensity rules in each case."
    },
    {
        "anchor": "A Gate-Induced Switch in Zigzag Graphene Naoribbons and Charging Effects: Using non-equilibrium Green's function formalism, we investigate nonlinear\ntransport and charging effects of gated graphene nanoribbons (GNRs) with even\nnumber of zigzag chains. We find a negative differential resistance (NDR) over\na wide range of gate voltages with on/off ratio $\\sim 10^6$ for narrow enough\nribbons. This NDR originates from the parity selection rule and also\nprohibition of transport between discontinues energy bands. Since the external\nfield is well screened close to the contacts, the NDR is robust against the\nelectrostatic potential. However, for voltages higher than the NDR threshold,\ndue to charge transfer through the edges of ZGNR, screening is reduced such\nthat the external potential can penetrate inside the ribbon giving rise to\nsmaller values of off current. Furthermore, on/off ratio of the current depends\non the aspect ratio of the length/width and also edge impurity. Moreover,\non/off ratio displays a power law behavior as a function of ribbon length.",
        "positive": "Investigation of the tunnel magnetoresistance in junctions with a\n  strontium stannate barrier: We experimentally investigate the structural, magnetic and electrical\ntransport properties of La$_{0.67}$Sr$_{0.33}$MnO$_{3}$ based magnetic tunnel\njunctions with a SrSnO$_3$ barrier. Our results show that despite the large\nnumber of defects in the strontium stannate barrier, due to the large lattice\nmismatch, the observed tunnel magnetoresistance is comparable to tunnel\njunctions with a better lattice matched STiO$_3$ barrier, reaching values of up\nto 350% at T=5 K. Further analysis of the current-voltage characteristics of\nthe junction and the bias voltage dependence of the observed tunnel\nmagnetoresistance show a decrease of the TMR with increasing bias voltage. In\naddition, the observed TMR vanishes for T>200 K. Our results suggest that by\nemploying a better lattice matched ferromagnetic electrode and thus reducing\nthe structural defects in the strontium stannate barrier even larger TMR ratios\nmight be possible in the future."
    },
    {
        "anchor": "Lorentzian quantum wells in graphene: the role of shape invariance in\n  zero-energy states trapping: Confining Dirac fermions in graphene by electrostatic fields is a challenging\ntask. Electric quantum dots created by a scanning tunneling microscope (STM)\ntip can trap zero-energy quasi-particles. The Lorentzian quantum well provides\na faithful, exactly solvable, approximation to such a potential, hosting\nzero-energy bound states for certain values of the coupling constant. We show\nthat in this critical configuration, the system can be related to the free\nparticle model by means of a supersymmetric transformation. The revealed shape\ninvariance of the model greatly simplifies the calculation of the zero modes\nand naturally explains the degeneracy of the zero energy.",
        "positive": "Supercurrent-induced Majorana bound states in a planar geometry: We propose a new setup for creating Majorana bound states in a\ntwo-dimensional electron gas Josephson junction. Our proposal relies\nexclusively on a supercurrent parallel to the junction as a mechanism of\nbreaking time-reversal symmetry. We show that combined with spin-orbit\ncoupling, supercurrents induce a Zeeman-like spin splitting. Further, we\nidentify a new conserved quantity---charge-momentum parity---that prevents the\nopening of the topological gap by the supercurrent in a straight Josephson\njunction. We propose breaking this conservation law by adding a third\nsuperconductor, introducing a periodic potential, or making the junction\nzigzag-shaped. By comparing the topological phase diagrams and practical\nlimitations of these systems we identify the zigzag-shaped junction as the most\npromising option."
    },
    {
        "anchor": "Helical boundary modes from synthetic spin in a plasmonic lattice: Artificial lattices have been used as a platform to extend the application of\ntopological physics beyond electronic systems. Here, using the two-dimensional\nLieb lattice as a prototypical example, we show that an array of disks which\neach support localized plasmon modes give rise to an analog of the quantum spin\nHall state enforced by a synthetic time reversal symmetry. We find that an\neffective next-nearest-neighbor coupling mechanism intrinsic to the plasmonic\ndisk array introduces a nontrivial $Z_2$ topological order and gaps out the\nBloch spectrum. A faithful mapping of the plasmonic system onto a tight-binding\nmodel is developed and shown to capture its essential topological signatures.\nFull wave numerical simulations of graphene disks arranged in a Lieb lattice\nconfirm the existence of propagating helical boundary modes in the nontrivial\nband gap.",
        "positive": "Magnetic-Field-Driven Antiferromagnetic Domain Wall Motion: We theoretically study the antiferromagnetic domain wall motion actuated by\nan inhomogeneous external magnetic field. The Lagrangian and the equations of\nmotion of antiferromagnetic spins under an inhomogeneous magnetic field are\nderived, first in terms of the N\\'eel vector, and then using collective\ncoordinates of the domain wall. A solution is found that describes the\nactuation of a domain wall by an inhomogeneous field, in which the motion is\ninitiated by a paramagnetic response of wall magnetization, which is then\ndriven by a Stern-Gerlach like force. The effects of pinning potential are also\ninvestigated. These results are in good agreement with atomistic simulations.\nWhile the present formulation contains the so-called intrinsic magnetization\nassociated with N\\'eel texture, a supplementary discussion is given to\nreformulate the theory in terms of physical magnetization without the intrinsic\nmagnetization."
    },
    {
        "anchor": "Theory and design of quantum cascade lasers in (111) n-type Si/SiGe: Although most work toward the realization of group IV quantum cascade lasers\n(QCLs) has focused on valence-band transitions, there are many desirable\nproperties associated with the conduction band. We show that the commonly cited\nshortcomings of n-type Si/SiGe heterostructures can be overcome by moving to\nthe (111) growth direction. Specifically, a large band offset and low effective\nmass are achievable and subband degeneracy is preserved. We predict net gain up\nto lattice temperatures of 90 K in a bound-to-continuum QCL with a double-metal\nwaveguide, and show that a Ge interdiffusion length of at least 8 angstroms\nacross interfaces is tolerable.",
        "positive": "Magnetism of Edge Modified Nano Graphene: In order to study a magnetic principle of carbon based materials, multiple\nspin state of zigzag edge modified graphene molecules are analyzed by the first\nprinciple density functional theory to select suitable modification element.\nRadical carbon modified C64H17 shows that the highest spin state is most\nstable, which arises from two up-spin's tetrahedral molecular orbital\nconfiguration at zigzag edge. In contrast, oxygen modified C59O5H17 show the\nlowest spin state to be most stable due to four spins cancellation at oxygen\nsite. Boron modified C59B5H22 have no {\\pi}-molecular orbit at boron site to\nbring stable molecular spin state to be the lowest one. Whereas, C59N5H2 have\ntwo {\\pi}-electrons, where spins cancel each other to give the stable lowest\nspin state. Silicon modified C59Si5H27 and Phosphorus modified C59P5H22 show\ncurved molecular geometry due to a large atom insertion at zigzag site, which\nalso bring complex spin distribution. Radical carbon and dihydrogenated carbon\nmodification are promising candidates for designing carbon-based magnetic\nmaterials."
    },
    {
        "anchor": "Theory of Hole-Spin Qubits in Strained Germanium Quantum Dots: We theoretically investigate the properties of holes in a\nSi$_{x}$Ge$_{1-x}$/Ge/ Si$_{x}$Ge$_{1-x}$ quantum well in a perpendicular\nmagnetic field that make them advantageous as qubits, including a large\n($>$100~meV) intrinsic splitting between the light and heavy hole bands, a very\nlight ($\\sim$0.05$\\, m_0$) in-plane effective mass, consistent with higher\nmobilities and tunnel rates, and larger dot sizes that could ameliorate\nconstraints on device fabrication. Compared to electrons in quantum dots, hole\nqubits do not suffer from the presence of nearby quantum levels (e.g., valley\nstates) that can compete with spins as qubits. The strong spin-orbit coupling\nin Ge quantum wells may be harnessed to implement electric-dipole spin\nresonance, leading to gate times of several nanoseconds for single-qubit\nrotations. The microscopic mechanism of this spin-orbit coupling is discussed,\nalong with its implications for quantum gates based on electric-dipole spin\nresonance, stressing the importance of coupling terms that arise from the\nunderlying cubic crystal field. Our results provide a theoretical foundation\nfor recent experimental advances in Ge hole-spin qubits.",
        "positive": "Optimal tunneling enhances quantum photovoltaic effect in double quantum\n  dots: We investigate quantum photovoltaic effect in double quantum dots by applying\nnonequilibrium quantum master equation. The drastic suppression of the\nphotovoltaic current is observed near the open circuit voltage, which leads to\nthe large filling factor. We find that there always exists an optimal inter-dot\ntunneling that significantly enhances the photovoltaic current. The maximal\noutput power will also be obtained around the optimal inter-dot tunneling.\nMoreover, the open circuit voltage approximately behaves as the product of the\neigen-level gap and the Carnot efficiency. These results suggest a great\npotential for double quantum dots as efficient photovoltaic devices."
    },
    {
        "anchor": "Quantum transport and mobility spectrum of topological carriers in (001)\n  SnTe/PbTe heterojunctions: Measurements of magnetotransport in SnTe/PbTe heterojunctions grown by the\nMBE technique on (001) undoped CdTe substrates were performed. At low magnetic\nfields, quantum corrections to conductivity were observed that may be\nattributed to the presence of topological states at the junction interface. For\na sample with 5 nm thick SnTe layer, the data analysis suggests that midgap\nstates are actually gapped. However, the phase coherence effects in 10 nm and\n20 nm SnTe/PbTe samples are fully explained assuming existence of gapless Dirac\ncones. Magnetotransport at higher magnetic fields is described in the framework\nof mobility spectrum analysis (MSA). We demonstrate that the electron- and\nhole-like peaks observed simultaneously for all SnTe/PbTe heterojunctions may\noriginate from the concave and convex parts of the energy isosurface for\ntopological states -- and not from the existence of quasiparticles both\ncarrying negative and positive charges. This interpretation is supported by\nnumerical calculations of conductivity tensor components for gapless (100)\nDirac cones, performed within a classical model and based on the solutions of\nBoltzmann transport equation. Our approach shows the feasibility of MSA in\napplication to magnetotransport measurements on topological matter.",
        "positive": "Magnetic field-Induced Nonlinear Optical Responses in Inversion\n  Symmetric Dirac Semimetals: We show that, under the effect of an external magnetic field, a photogalvanic\neffect and the generation of second harmonic wave can be induced in\ninversion-symmetric and time reversal invariant Dirac semimetals. The mechanism\nresponsible of these non linear optical responses is the magnetochiral effect.\nThe origin of this magnetochiral effect is the band bending of the dispersion\nrelation in real Dirac semimetals. Some observable consequences of this\nphenomenon are the appearance of a dc current on the surface of the system when\nit is irradiated with linearly polarized light or a rotation of the\npolarization plane of the reflected second harmonic wave."
    },
    {
        "anchor": "The Synthesis and Electrical Transport of Ligand-Protected Au13 Clusters: The ligand-protected Au13 clusters have been synthesized by using\nmeso-2,3-imercaptosuccinic acid as the reducing and stabilizing agent.\nTransmission electron microscopic analysis shows a size distribution of 0.6nm.\nOptical spectrum shows an absorbance peak at 390 nm. The electrical transport\nmeasurement devices are fabricated using the electro-migration method. Coulomb\nblockade is observed at the temperature of 1.6 K,revealing the formation of the\ntunneling junction. The Coulomb oscillation on-off ratio is nearly 5. Three\npeaks are extracted in the dI-dV data and attributed to the energy levels of\nAu13 clusters, gapped by about 60 meV. First principle calculations are carried\nout to interpret the energy diagram.",
        "positive": "Observation of half-integer thermal Hall conductance: Topological states of matter are characterized by topological invariant,\nwhich are physical quantities whose values are quantized and do not depend on\ndetails of the measured system. Of these, the easiest to probe in experiments\nis the electrical Hall conductance, which is expressed in units of $e^2/h$ ($e$\nthe electron charge, $h$ the Planck's constant). In the fractional quantum Hall\neffect (FQHE), fractional quantized values of the electrical Hall conductance\nattest to topologically ordered states, which are states that carry quasi\nparticles with fractional charge and anyonic statistics. Another topological\ninvariant, which is much harder to measure, is the thermal Hall conductance,\nexpressed in units of $\\kappa_0T=(\\pi^2kB^2/3h)T$ ($kB$ the Boltzmann constant,\n$T$ the temperature). For the quantized thermal Hall conductance, a fractional\nvalue attests that the probed state of matter is non-abelian. Quasi particles\nin non-abelian states lead to a ground state degeneracy and perform topological\nunitary transformations among ground states when braided. As such, they may be\nuseful for topological quantum computation. In this paper, we report our\nmeasurements of the thermal Hall conductance for several quantum Hall states in\nthe first excited Landau level. Remarkably, we find the thermal Hall\nconductance of the $\\nu=5/2$ state to be fractional, and to equal\n$2.5\\kappa_0T$"
    },
    {
        "anchor": "A numerical method to efficiently calculate the transport properties of\n  large systems: an algorithm optimized for sparse linear solvers: We present a self-contained description of the wave-function matching (WFM)\nmethod to calculate electronic quantum transport properties of nanostructures\nusing the Landauer-B\\\"uttiker approach. The method is based on a partition of\nthe system between a central region (\"conductor\") containing $N_S$ sites and an\nasymptotic region (\"leads\") characterized by $N_P$ open channels. The two\nsubsystems are linearly coupled and solved simultaneously using an efficient\nsparse linear solver. Invoking the sparsity of the Hamiltonian matrix\nrepresentation of the central region, we show that the number of operations\nrequired by the WFM method in conductance calculations scales with $\\sim\nN_S\\times N_P$ for large $N_S$.",
        "positive": "Electronic response of graphene to linelike charge perturbations: The problem of electrostatic screening of a charged line by undoped or weakly\ndoped graphene is treated beyond the linear-response theory. The induced\nelectron density is found to be approximately doping independent, n(x)~(log\nx)^2/x^2, at intermediate distances x from the charged line. At larger x, twin\np-n junctions may form if the external perturbation is repulsive for graphene\ncharge carriers. The effect of such inhomogeneities on conductance and quantum\ncapacitance of graphene is calculated. The results are relevant for transport\nproperties of graphene grain boundaries and for local electrostatic control of\ngraphene with ultrathin gates."
    },
    {
        "anchor": "Observation of Negative Surface and Interface Energies of Quantum Dots: Surface energy is a fundamental property of materials and is particularly\nimportant in describing nanomaterials where atoms or molecules at the surface\nconstitute a large fraction of the material. Traditionally, surface energy is\nconsidered to be a positive quantity, where atoms or molecules at the surface\nare less thermodynamically stable than their counterparts in the interior of\nthe material because they have fewer bonds or interactions at the surface.\nUsing calorimetric methods, we show that the surface energy is negative in some\nprototypical colloidal semiconductor nanocrystals, or quantum dots with organic\nligand coatings. This implies that the surface atoms are more thermodynamically\nstable than those on the interior due to the strong bonds between these atoms\nand surfactant molecules, or ligands, that coat their surface. In addition, we\nextend this work to core/shell indium phosphide/zinc sulfide nanocrystals and\nshow that the interfacial energy between these materials is highly\nthermodynamically favorable in spite of their large lattice mismatch. This work\nchallenges many of the assumptions that have guided thinking about colloidal\nnanomaterial thermodynamics, illustrates the fundamental stability of many\ntechnologically relevant colloidal nanomaterials, and paves the way for future\nexperimental and theoretical work on nanocrystal thermodynamics.",
        "positive": "Indication of intrinsic spin Hall effect in 4d and 5d transition metals: We have investigated spin Hall effects in 4$d$ and 5$d$ transition metals,\nNb, Ta, Mo, Pd and Pt, by incorporating the spin absorption method in the\nlateral spin valve structure; where large spin current preferably relaxes into\nthe transition metals, exhibiting strong spin-orbit interactions. Thereby\nnonlocal spin valve measurements enable us to evaluate their spin Hall\nconductivities. The sign of the spin Hall conductivity changes systematically\ndepending on the number of $d$ electrons. This tendency is in good agreement\nwith the recent theoretical calculation based on the intrinsic spin Hall\neffect."
    },
    {
        "anchor": "Nanomaterials of the topological crystalline insulators,\n  Pb_(1-x)Sn_(x)Te and Pb_(1-x)Sn_(x)Se: Topological insulators (TIs) and topological crystal insulators (TCIs)\nexhibit exotic surface properties. We present optimised growth procedures to\nobtain high quality bulk crystals of the TCIs Pb_(1-x)Sn_(x)Te and\nPb_(1-x)Sn_(x)Se, and nanowires from the bulk crystals using the\nvapour-liquid-solid (VLS) technique. Nanowires of Pb_(1-x)Sn_(x)Te have been\nproduced with a Sn composition of approx. x = 0.25, at which a transition from\ntrivial to non-trivial insulator is reported. The results obtained on the\ngrowth of nanomaterials of Pb_(1-x)Sn_(x)Se are also described. Detailed\ncharacterisation of the bulk crystals and the nanomaterials through x-ray\ndiffraction, microscopy techniques and EDX analysis are presented.",
        "positive": "Renormalization group analysis of weakly interacting van der Waals Fermi\n  system: Weak-coupling phenomena of the two-dimensional Hubbard model is gaining\nmomentum as a new interesting research field due to its extraordinarily rich\nbehavior as a function of the carrier density and model parameters. Salmhofer\n[{\\it Commun. Math. Phys}. \\textbf{194}, 249 (1998);{\\it Phys. Rev. Lett}. {\\bf\n87}, 187004 (2001)] developed a new renormalization-group method for\ninteracting Fermi systems and Metzner [{\\it Phys. Rev. B} {\\bf 61}, 7364\n(2000);{\\it Phys. Rev. Lett}. {\\bf 85}, 5162 (2000)] implemented this\nrenormalization group analysis of the two-dimensional Hubbard model. In this\nwork, we demonstrate the spin-wave dependent susceptibility behavior of model\ngraphene-phosphorene van der Waals heterostructure in the framework of\nrenormalization group approach. We implement signlet vertex response function\nfor the weakly interacting van der Waals Fermi system with nearest-neighbor\nhopping amplitudes. This analytical approach is further correlated with {\\it ab\ninitio} simulation results and extended for spin-wave dependent susceptibility\nbehavior with possible experimental protocols. We present the resulting\ncompressibility and phase diagram in the vicinity of half-filling, and also\nresults for the density dependence of the critical energy scale."
    },
    {
        "anchor": "Bucky-Corn: Van der Waals Composite of Carbon Nanotube Coated by\n  Fullerenes: Can C60 layer cover a surface of single-wall carbon nanotube (SWCNT) forming\nan exohedral pure-carbon hybrid with only VdW interactions? The paper addresses\nthis question and demonstrates that the fullerene shell layer in such a\nbucky-corn structure can be stable. Theoretical study of structure, stability\nand electronic properties of the following bucky-corn hybrids is reported: C60\nand C70 molecules on an individual SWCNT, C60 dimers on an individual SWCNT as\nwell C60 molecules on SWNT bundles. The geometry and total energies of the\nbucky-corns were calculated by the molecular dynamics method while the density\nfunctional theory method was used to simulate the electronic band structures.",
        "positive": "Effect of exchange electron-electron interaction on conductivity of\n  InGaAs single and double quantum wells in ballistic regime: We report an experimental study of quantum conductivity corrections for\ntwo-dimensional electron gas in a GaAs/InGaAs/GaAs single and double quantum\nwells in a wide temperature range (1.8-100) K. We perform a comparison of our\nexperimental data for the longitudinal conductivity at zero magnetic field to\nthe theory of interaction-induced corrections to th transport coefficients. In\nthe temperature range from 10 K up to (45-60) K, wich covers the ballistic\ninteraction regimes for our samples, a rather good agreement between the theory\nand our experimental results has been found."
    },
    {
        "anchor": "Novel Properties of The Apparent Metal-Insulator Transition in\n  Two-Dimensional Systems: The low-temperature conductivity of low-density, high-mobility,\ntwo-dimensional hole systems in GaAs was studied. We explicitly show that the\nmetal-insulator transition, observed in these systems, is characterized by a\nwell-defined critical density, p_0c. We also observe that the low-temperature\nconductivity of these systems depends linearly on the hole density, over a wide\ndensity range. The high-density linear conductivity extrapolates to zero at a\ndensity close to the critical density.",
        "positive": "Universal angular magnetoresistance and spin torque in\n  ferromagnetic/normal metal hybrids: The electrical resistance of ferromagnetic/normal-metal (F/N)\nheterostructures depends on the nature of the junctions which may be tunnel\nbarriers, point contacts, or intermetallic interfaces. For all junction types,\nthe resistance of disordered F/N/F perpendicular spin valves as a function of\nthe angle between magnetization vectors is shown to obey a simple universal\nlaw. The spin-current induced magnetization torque can be measured by the\nangular magnetoresistance of these spin valves. The results are generalized to\narbitrary magnetoelectronic circuits."
    },
    {
        "anchor": "Shot Noise Induced by Electron-nuclear Spin-flip Scattering in a\n  Nonequilibrium Quantum Wire: We study the shot noise (nonequilibrium current fluctuation) associated with\ndynamic nuclear polarization in a nonequilibrium quantum wire (QW) fabricated\nin a two-dimensional electron gas. We observe that the spin-polarized\nconductance quantization of the QW in the integer quantum Hall regime collapses\nwhen the QW is voltage biased to be driven to nonequilibrium. By measuring the\nshot noise, we prove that the spin polarization of electrons in the QW is\nreduced to $\\sim 0.7$ instead of unity as a result of electron-nuclear\nspin-flip scattering. The result is supported by Knight shift measurements of\nthe QW using resistively detected NMR.",
        "positive": "Periodic revival of entanglement of two strongly driven qubits in a\n  dissipative cavity: We study the dynamics and decoherence of a system of two strongly driven\nqubits in a dissipative cavity. The two qubits have no direct interaction and\nare individually off-resonantly coupled to a single mode of quantized\nradiation. We derive analytical solutions to the Lindblad-type master equation\nand study the evolution of the entanglement of this system. We show that with\nnon-zero detuning between the quantum and classical fields, the initial decay\nof the entanglement is followed by its revival periodic in time. We show that\ndifferent Bell states follow evolutions with different rates."
    },
    {
        "anchor": "Spin Gating of Mesoscopic Devices: Inefficient screening of electric fields in nanoconductors makes electric\nmanipulation of electronic transport in nanodevices possible. Accordingly,\nelectrostatic (charge) gating is routinely used to affect and control the\nCoulomb electrostatics and quantum interference in modern nanodevices. Besides\ntheir charge, another (quantum mechanical) property of electrons - their spin -\nis at the heart of modern spintronics, a term implying that a number of\nmagnetic and electrical properties of small systems are simultaneously\nharvested for device applications. In this review the possibility to achieve\n\"spin gating\" of mesoscopic devices, i.e. the possibility of an external spin\ncontrol of the electronic properties of nanodevices is discussed. Rather than\nthe Coulomb interaction, which is responsible for electric-charge gating, we\nconsider two other mechanisms for spin gating. These are on the one hand the\nmagnetic exchange interaction in magnetic devices and on the other hand the\nspin-orbit coupling (\"Rashba effect\"), which is prominent in low dimensional\nconductors. A number of different phenomena demonstrating the spin gating\nphenomenon will be discussed, including the spintro-mechanics of magnetic\nshuttling, Rashba spin splitting, and spin-gated weak superconductivity.",
        "positive": "Interband polarized absorption in InP polytypic superlattices: Recent advances in growth techniques have allowed the fabrication of\nsemiconductor nanostructures with mixed wurtzite/zinc-blende crystal phases.\nAlthough the optical characterization of these polytypic structures is well\neported in the literature, a deeper theoretical understanding of how crystal\nphase mixing and quantum confinement change the output linear light\npolarization is still needed. In this paper, we theoretically investigate the\nmixing effects of wurtzite and zinc-blende phases on the interband absorption\nand in the degree of light polarization of an InP polytypic superlattice. We\nuse a single 8$\\times$8 k$\\cdot$p Hamiltonian that describes both crystal\nphases. Quantum confinement is investigated by changing the size of the\npolytypic unit cell. We also include the optical confinement effect due to the\ndielectric mismatch between the superlattice and the vaccum and we show it to\nbe necessary to match experimental results. Our calculations for large wurtzite\nconcentrations and small quantum confinement explain the optical trends of\nrecent photoluminescence excitation measurements. Furthermore, we find a high\nsensitivity to zinc-blende concentrations in the degree of linear polarization.\nThis sensitivity can be reduced by increasing quantum confinement. In\nconclusion, our theoretical analysis provides an explanation for optical trends\nin InP polytypic superlattices, and shows that the interplay of crystal phase\nmixing and quantum confinement is an area worth exploring for light\npolarization engineering."
    },
    {
        "anchor": "Mesoscopic Elastic Distortions in GaAs Quantum Dot Heterostructures: Quantum devices formed in high-electron-mobility semiconductor\nheterostructures provide a route through which quantum mechanical effects can\nbe exploited on length scales accessible to lithography and integrated\nelectronics. The electrostatic definition of quantum dots in semiconductor\nheterostructure devices intrinsically involves the lithographic fabrication of\nintricate patterns of metallic electrodes. The formation of metal/semiconductor\ninterfaces, growth processes associated with polycrystalline metallic layers,\nand differential thermal expansion produce elastic distortion in the active\nareas of quantum devices. Understanding and controlling these distortions\npresents a significant challenge in quantum device development. We report\nsynchrotron x-ray nanodiffraction measurements combined with dynamical x-ray\ndiffraction modeling that reveal lattice tilts with a depth-averaged value up\nto 0.04 deg. and strain on the order of 10^-4 in the two-dimensional electron\ngas (2DEG) in a GaAs/AlGaAs heterostructure. Elastic distortions in GaAs/AlGaAs\nheterostructures modify the potential energy landscape in the 2DEG due to the\ngeneration of a deformation potential and an electric field through the\npiezoelectric effect. The stress induced by metal electrodes directly impacts\nthe ability to control the positions of the potential minima where quantum dots\nform and the coupling between neighboring quantum dots.",
        "positive": "Anomalous thermodiffusion of electrons in graphene: We reveal a dramatic departure of electron thermodiffusion in solids relative\nto the commonly accepted picture of the ideal free-electron gas model. In\nparticular, we show that the interaction with the lattice and impurities,\ncombined with a strong material dependence of the electron dispersion relation,\nleads to counterintuitive diffusion behavior, which we identify by comparing a\nsingle-layer two-dimensional electron gas (2DEG) and graphene. When subject to\na temperature gradient $\\nabla T$, thermodiffusion of massless Dirac electrons\nin graphene exhibits an anomalous behavior with electrons moving along $\\nabla\nT$ and accumulating in hot regions, in contrast to normal electron diffusion in\na 2DEG with parabolic dispersion, where net motion against $\\nabla T$ is\nobserved, accompanied by electron depletion in hot regions. These findings have\nfundamentally importance for the understanding of the spatial electron dynamics\nin emerging material, establishing close relations with other branches of\nphysics dealing with electron systems under nonuniform temperature conditions."
    },
    {
        "anchor": "Room temperature current suppression on multilayer edge molecular\n  spintronics device: Molecular conduction channels between two ferromagnetic electrodes can\nproduce strong exchange coupling and dramatic effect on the spin transport,\nthus enabling the realization of novel logic and memory devices. However,\nfabrication of molecular spintronics devices is extremely challenging and\ninhibits the insightful experimental studies. Recently, we produced Multilayer\nEdge Molecular Spintronics Devices (MEMSDs) by bridging the organometallic\nmolecular clusters (OMCs) across a ~2 nm thick insulator of a magnetic tunnel\njunction (MTJ), along its exposed side edges. These MEMSDs exhibited\nunprecedented increase in exchange coupling between ferromagnetic films and\ndramatic changes in the spin transport. This paper focuses on the dramatic\ncurrent suppression phenomenon exhibited by MEMSDs at room temperature. In the\nevent of current suppression, the effective MEMESDs' current reduced by as much\nas six orders in magnitude as compared to the leakage current level of a MTJ\ntest bed. In the suppressed current state, MEMSD's transport could be affected\nby the temperature, light radiation, and magnetic field. In the suppressed\ncurrent state MEMSD also showed photovoltaic effect. This study motivates the\ninvestigation of MEMSDs involving other combinations of MTJs and promising\nmagnetic molecules like single molecular magnets and porphyrin. Observation of\ncurrent suppression on similar systems will unequivocally establish the utility\nof MEMSD approach.",
        "positive": "Anchoring ceria nanoparticles on reduced graphene oxide and their\n  electronic transport properties: This paper has been withdrawn."
    },
    {
        "anchor": "Lateral vibration effects in atomic-scale friction: The influence of lateral vibrations on the stick-slip motion of a nanotip\nelastically pulled on a flat crystal surface is studied by atomic force\nmicroscopy (AFM) measurements on a NaCl(001) surface in ultra-high vacuum. The\nslippage of the nanotip across the crystal lattice is anticipated at increasing\ndriving amplitude, similarly to what is observed in presence of normal\nvibrations. This lowers the average friction force, as explained by the\nPrandtl-Tomlinson model with lateral vibrations superimposed at finite\ntemperature. Nevertheless, the peak values of the lateral force, and the total\nenergy losses, are expected to increase with the excitation amplitude, which\nmay limit the practical relevance of this effect.",
        "positive": "Magnetization reversal driven by spin-injection : a mesoscopic\n  spin-transfer effect: A mesoscopic description of spin-transfer effect is proposed, based on the\nspin-injection mechanism occurring at the junction with a ferromagnet. The\neffect of spin-injection is to modify locally, in the ferromagnetic\nconfiguration space, the density of magnetic moments. The corresponding\ngradient leads to a current-dependent diffusion process of the magnetization.\nIn order to describe this effect, the dynamics of the magnetization of a\nferromagnetic single domain is reconsidered in the framework of the\nthermokinetic theory of mesoscopic systems. Assuming an Onsager\ncross-coefficient that couples the currents, it is shown that spin-dependent\nelectric transport leads to a correction of the Landau-Lifshitz-Gilbert\nequation of the ferromagnetic order parameter with supplementary diffusion\nterms. The consequence of spin-injection in terms of activation process of the\nferromagnet is deduced, and the expressions of the effective energy barrier and\nof the critical current are derived. Magnetic fluctuations are calculated: the\ncorrection to the fluctuations is similar to that predicted for the activation.\nThese predictions are consistent with the measurements of spin-transfer\nobtained in the activation regime and for ferromagnetic resonance under\nspin-injection."
    },
    {
        "anchor": "The critical role of substrate disorder in valley splitting in Si\n  quantum wells: Motivated by theoretical predictions that spatially complex concentration\nmodulations of Si and Ge can increase the valley splitting in quantum wells, we\ngrow and characterize Si/SiGe heterostructures with a thin, pure Ge layer at\nthe top of the quantum well using chemical vapor deposition. We show that these\nheterostructures remain hosts for high-mobility electron gases. We measure two\nquantum wells with approximately five monolayers of pure Ge at the upper\nbarrier, finding mobilities as high as 70,000 cm$^2$/Vs, compared to 100,000\ncm$^2$/Vs measured in samples with no Ge layer. Activation energy measurements\nin quantum Hall states corresponding to Fermi levels in the gap between\ndifferent valley states reveal energy gaps ranging from 30 to over 200 $\\mu$eV,\nand we extract a surprisingly strong dependence of the energy gap on electron\ndensity. We interpret our results using tight binding theory and argue that our\nresults are evidence that atomic scale disorder at the quantum well interface\ndominates the behavior of the valley splittings of these modified\nheterostructures.",
        "positive": "Phonons in magic-angle twisted bilayer graphene: Magic-angle twisted bilayer graphene (TBG) has attracted significant interest\nrecently due to the discoveries of diverse correlated and topological states in\nthis system. Despite the extensive research on the electron-electron\ninteraction effects and topological properties of the electrons, the phonons of\nmagic-angle TBG are relatively less explored. In this work, we study the phonon\nproperties in magic-angle TBG based on \\textit{ab} \\textit{initio} deep\npotential molecular dynamics. We have calculated phonon band structures and\ndensity of states at the magic angle, and have systematically analyzed the\nphonon eigenmodes at high-symmetry points in the moir\\'e Brillouin zone. In\nparticular, at the moir\\'e $\\Gamma$ point, we have discovered a number of soft\nmodes which can exhibit dipolar-like, stripe-like, and octupolar-like\nvibrational patterns within the moir\\'e supercell, as well as some \"vortical\"\nmodes with nonzero curl in real space. At the moir\\'e $K$/$K'$ points, there\nare time-reversal breaking chiral phonon modes with nonzero local phonon\npolarizations. We have further studied the phonon effects on the electronic\nstructures by freezing certain soft phonon modes. We find that if a soft\n\"stripe\" phonon mode at moir\\'e $\\Gamma$ point is assumed to be frozen, the\nsystem would exhibit a charge order which naturally explains the recent\nobservations from scanning tunnelling microscopy. Moreover, there are also\nlow-frequency $C_{2z}$-breaking modes at moir\\'e $\\Gamma$ point, which would\ngap out the Dirac points at the charge neutrality point once these modes get\nfrozen. This provides a new perspective to the origin of correlated insulator\nstate at the charge neutrality point."
    },
    {
        "anchor": "Gate-voltage induced trions in suspended carbon nanotubes: We observe trion emission from suspended carbon nanotubes where carriers are\nintroduced electrostatically using field-effect transistor structures. The\ntrion peak emerges below the $E_{11}$ emission energy at gate voltages that\ncoincide with the onset of bright exciton quenching. By investigating nanotubes\nwith various chiralities, we verify that the energy separation between the\nbright exciton peak and the trion peak becomes smaller for larger diameter\ntubes. Trion binding energies that are significantly larger compared to\nsurfactant-wrapped carbon nanotubes are obtained, and the difference is\nattributed to the reduced dielectric screening in suspended tubes.",
        "positive": "Selective area epitaxy of PbTe-Pb hybrid nanowires on a lattice-matched\n  substrate: Topological quantum computing is based on braiding of Majorana zero modes\nencoding topological qubits. A promising candidate platform for Majorana zero\nmodes is semiconductor-superconductor hybrid nanowires. The realization of\ntopological qubits and braiding operations requires scalable and disorder-free\nnanowire networks. Selective area growth of in-plane InAs and InSb nanowires,\ntogether with shadow-wall growth of superconductor structures, have\ndemonstrated this scalability by achieving various network structures. However,\nthe noticeable lattice mismatch at the nanowire-substrate interface, acting as\na disorder source, imposes a serious obstacle along with this roadmap. Here,\ncombining selective area and shadow-wall growth, we demonstrate the fabrication\nof PbTe-Pb hybrid nanowires - another potentially promising Majorana system -\non a nearly perfectly lattice-matched substrate CdTe, all done in one molecular\nbeam epitaxy chamber. Transmission electron microscopy shows the single-crystal\nnature of the PbTe nanowire and its atomically sharp and clean interfaces to\nthe CdTe substrate and the Pb overlayer, without noticeable inter-diffusion or\nstrain. The nearly ideal interface condition, together with the strong\nscreening of charge impurities due to the large dielectric constant of PbTe,\nhold promise towards a clean nanowire system to study Majorana zero modes and\ntopological quantum computing."
    },
    {
        "anchor": "Strong Electronic Correlation Originates from the Synergistic Effect of\n  Large Moir\u00e9 Cell and Strong Interlayer Coupling in Twisted Graphene Bilayer: By using the first-principles method based on density of functional theory,\nwe study the electronic properties of twisted bilayer graphene with some\nspecific twist angles and interlayer spacings. With the decrease of the twist\nangle(the unit cell becomes larger), the energy band becomes narrower and\nCoulomb repulsion increases, leading to the enhancement of electronic\ncorrelation; On the other hand, as the interlayer spacing decreases and the\ninterlayer coupling becomes stronger, the correlation becomes stronger. By\ntuning the interlayer coupling, we can realize the strongly correlated state\nwith the band width less than 0.01 eV in medium-sized Moir\\'e cell of twisted\nbilayer graphene. These results demonstrate that the strength of electronic\ncorrelation in twisted bilayer graphene is closely related to two factors: the\nsize of unit cell and the distance between layers. Consequently, a conclusion\ncan be drawn that the strong electronic correlation in twisted bilayer graphene\noriginates from the synergistic effect of the large size of Moir\\'e cell and\nstrong interlayer coupling on its electronic structure.",
        "positive": "Optomechanical measurement of thermal transport in two-dimensional MoSe2\n  lattices: Nanomechanical resonators have emerged as sensors with exceptional\nsensitivities. These sensing capabilities open new possibilities in the studies\nof the thermodynamic properties in condensed matter. Here, we use mechanical\nsensing as a novel approach to measure the thermal properties of\nlow-dimensional materials. We measure the temperature dependence of both the\nthermal conductivity and the specific heat capacity of a transition metal\ndichalcogenide (TMD) monolayer down to cryogenic temperature, something that\nhas not been achieved thus far with a single nanoscale object. These\nmeasurements show how heat is transported by phonons in two-dimensional\nsystems. Both the thermal conductivity and the specific heat capacity\nmeasurements are consistent with predictions based on first-principles."
    },
    {
        "anchor": "Helical networks in twisted bilayer graphene under interlayer bias: A twisted graphene bilayer exhibits a triangular Moir\\'e pattern in the local\nstacking, that smoothly alternates between the three basic types AA', AB' and\nBA'. Under an interlayer bias U, the latter two types develop a spectral gap,\ncharacterised by opposite valley Chern numbers. We show that for large enough\nMoir\\'e periods and bias, these regions become depleted electronically, and\ntopologically protected helical modes appear at their boundaries. This gives\nrise to a delocalised topological network of the Chalker-Coddington type,\ncomposed of valley current vortices. This network can be tailored by controlled\ndeposition of valley-mixing adsorbates, which block transmission in selected\nlinks, thus opening the possibility of custom topological nanoelectronics.",
        "positive": "Insulator-metal transition in biased finite polyyne systems: A method for the study of the electronic transport in strongly coupled\nelectron-phonon systems is formalized and applied to a model of polyyne chains\nbiased through metallic Au leads. We derive a stationary non equilibrium\npolaronic theory in the general framework of a variational formulation. The\nnumerical procedure we propose can be readily applied if the electron-phonon\ninteraction in the device hamiltonian can be approximated as an effective\nsingle particle electron hamiltonian. Using this approach, we predict that\nfinite polyyne chains should manifest an insulator-metal transition driven by\nthe non-equilibrium charging which inhibits the Peierls instability\ncharacterizing the equilibrium state."
    },
    {
        "anchor": "Classification of Weyl points and nodal lines based on magnetic point\n  groups for spin-$\\frac{1}{2}$ quasiparticles: Symmetry-protected topological semimetals are at the focus of solid-state\nresearch due to their unconventional properties, for example, regarding\ntransport. By investigating local two-band Bloch Hamiltonians in the spin-1/2\nbasis for the 122 magnetic point groups, we classify twofold-degenerate band\ntouchings such as Weyl points, robust nodal lines on axes and in mirror planes,\nand fragile nodal lines. We find that all magnetic point groups that lack the\nproduct of inversion and time-reversal symmetries can give rise to\ntopologically nontrivial band touchings. Hence, such nodes are the rule rather\nthan the exception and, moreover, do not require any complicated multiband\nphysics. Our classification is applicable to every momentum in the Brillouin\nzone by considering the corresponding little group and provides a powerful tool\nto identify magnetic and nonmagnetic topological semimetals.",
        "positive": "Quantum Hall Effect: Current Distribution and Existence of Extended\n  States: We present a consistent description of the current distribution in the\nquantum Hall effect, based on two main ingredients: the location of the\nextended states and the distribution of the electric field. We show that the\ninteraction between electrons produces a boundary line below the Fermi energy,\nwhich extends from source to drain. The existence of this line and that of a\nphysical boundary are responsible for the formation of a {\\em band} of extended\nstates that carry the Hall current. The number and density of these extended\nstates are determined by the difference between the energy of this\nequipotential boundary line and the energy of the single extended state that\nwould exist in an infinite system. This is used to prove that the band of\nextended states is distributed through the bulk of the sample. We explore the\ndistribution of the Hall currents and electric fields in by presenting a model\nthat captures the main features of the charge relaxation processes. Theoretical\npredictions based on this model and on the preceding theory are used to\nunambiguously explain recent experimental findings."
    },
    {
        "anchor": "Thermal stability of monolayer $WS_2$ in BEOL conditions: Monolayer tungsten disulfide ($WS_2$) has recently attracted large interest\nas a promising material for advanced electronic and optoelectronic devices such\nas photodetectors, modulators, and sensors. Since these devices can be\nintegrated in a silicon (Si) chip via back-end-of-line (BEOL) processes, the\nstability of monolayer $WS_2$ in BEOL fabrication conditions should be studied.\nIn this work, the thermal stability of monolayer single-crystal $WS_2$ at\ntypical BEOL conditions is investigated; namely (i) heating temperature of\n$300$ $^\\circ C$, (ii) pressures in the medium- ($10^{-3}$ mbar) and high-\n($10^{-8}$ mbar) vacuum range; (iii) heating times from $30$ minutes to $20$\nhours. Structural, optical and chemical analyses of $WS_2$ are performed via\nscanning electron microscopy (SEM), Raman spectroscopy, photoluminescence (PL)\nand X-ray photoelectron spectroscopy (XPS). It is found that monolayer\nsingle-crystal $WS_2$ is intrinsically stable at these temperature and\npressures, even after $20$ hours of thermal treatment. The thermal stability of\n$WS_2$ is also preserved after exposure to low-current electron beam ($12$ pA)\nor low-fluence laser ($0.9$ $mJ/\\mu m^2$), while higher laser fluencies cause\nphoto-activated degradation upon thermal treatment. These results are\ninstrumental to define fabrication and in-line monitoring procedures that allow\nthe integration of $WS_2$ in device fabrication flows without compromising the\nmaterial quality.",
        "positive": "Thermodynamic properties of the one-dimensional Robin quantum well: Thermodynamic properties of Robin quantum well with extrapolation length\n$\\Lambda$ are analyzed theoretically both for canonical and two grand canonical\nensembles with special attention being paid to situation when energies of one\nor two lowest-lying states are split-off from rest of spectrum by large gap\nthat is controlled by varying $\\Lambda$. For single split-off level, which\nexists for the geometry with equal magnitudes but opposite signs of Robin\ndistances on confining interfaces, heat capacity $c_V$ of canonical averaging\nis a nonmonotonic function of temperature $T$ with its salient maximum growing\nto infinity as $\\ln^2\\Lambda$ for decreasing to zero extrapolation length and\nits position being proportional to $1/(\\Lambda^2\\ln\\Lambda)$. Specific heat per\nparticle $c_N$ of Fermi-Dirac ensemble depends nonmonotonically on temperature\ntoo with its pronounced extremum being foregone on $T$ axis by plateau whose\nvalue at dying $\\Lambda$ is $(N-1)/(2N)k_B$, with $N$ being a number of\nfermions. Maximum of $c_N$, similar to canonical averaging, unrestrictedly\nincreases as $\\Lambda$ goes to zero and is the largest for one particle. Most\nessential property of Bose-Einstein ensemble is a formation, for growing number\nof bosons, of sharp asymmetric shape on the $c_N-T$ characteristics that is\nmore protrusive at the smaller Robin distances. This cusp-like structure is a\nmanifestation of the phase transition to the condensate state. For two\nsplit-off orbitals, one additional maximum emerges whose position is shifted to\ncolder temperatures with increase of energy gap between these two states and\ntheir higher-lying counterparts and whose magnitude approaches\n$\\Lambda$-independent value. All these physical phenomena are qualitatively and\nquantitatively explained by variation of energy spectrum by Robin distance."
    },
    {
        "anchor": "Emission Noise in an Interacting Quantum Dot: Role of Inelastic\n  Scattering and Asymmetric Coupling to the Reservoirs: A theory is developed for the emission noise at frequency $\\nu$ in a quantum\ndot in the presence of Coulomb interactions and asymmetric couplings to the\nreservoirs. We give an analytical expression for the noise in terms of the\nvarious transmission amplitudes. Including inelastic scattering contribution,\nit can be seen as the analog of the Meir-Wingreen formula for the current. A\nphysical interpretation is given on the basis of the transmission of one\nelectron-hole pair to the concerned reservoir where it emits an energy after\nrecombination. We then treat the interactions by solving the self-consistent\nequations of motion for the Green functions. The results for the noise\nderivative versus $eV$ show a zero value until $eV = h\\nu$, followed by a Kondo\npeak in the Kondo regime, in good agreement with recent measurements in carbon\nnanotube quantum dots.",
        "positive": "First-principles calculation method for electron transport based on grid\n  Lippmann-Schwinger equation: We develop a first-principles electron-transport simulator based on the\nLippmann--Schwinger (LS) equation within the framework of the real-space\nfinite-difference scheme. In our fully real-space based LS (grid LS) method,\nthe ratio expression technique for the scattering wave functions and the\nGreen's function elements of the reference system is employed to avoid\nnumerical collapse. Furthermore, we present analytical expressions and/or\nprominent calculation procedures for the retarded Green's function, which are\nutilized in the grid LS approach. In order to demonstrate the performance of\nthe grid LS method, we simulate the electron-transport properties of the\nsemiconductor/oxide interfaces sandwiched between semi-infinite metal\nelectrodes. The results confirm that the leakage current through the\n(001)Si/SiO$_2$ model becomes much larger when the dangling-bond (DB) state is\ninduced by a defect in the oxygen layer while that through the (001)Ge/GeO$_2$\nmodel is insensitive to the DB state."
    },
    {
        "anchor": "Optical analogue of Dresselhaus spin-orbit interaction in photonic\n  graphene: The concept of gauge fields plays a significant role in many areas of physics\nfrom particle physics and cosmology to condensed matter systems, where gauge\npotentials are a natural consequence of electromagnetic fields acting on\ncharged particles and are of central importance in topological states of\nmatter. Here, we report on the experimental realization of a synthetic\nnon-Abelian gauge field for photons in a honeycomb microcavity lattice. We show\nthat the effective magnetic field associated with TE-TM splitting has the\nsymmetry of Dresselhaus spin-orbit interaction around Dirac points in the\ndispersion, and can be regarded as an SU(2) gauge field. The symmetry of the\nfield is revealed in the optical spin Hall effect (OSHE), where under resonant\nexcitation of the Dirac points precession of the photon pseudospin around the\nfield direction leads to the formation of two spin domains. Furthermore, we\nobserve that the Dresselhaus field changes its sign in the same Dirac valley on\nswitching from s to p bands in good agreement with the tight binding modelling.\nOur work demonstrating a non-Abelian gauge field for light on the microscale\npaves the way towards manipulation of photons via spin on a chip.",
        "positive": "Anomalous Floquet topological crystalline insulators: Periodically driven systems can host so called anomalous topological phases,\nin which protected boundary states coexist with topologically trivial Floquet\nbulk bands. We introduce an anomalous version of reflection symmetry protected\ntopological crystalline insulators, obtained as a stack of weakly-coupled\ntwo-dimensional layers. The system has tunable and robust surface Dirac cones\neven though the mirror Chern numbers of the Floquet bulk bands vanish. The\nnumber of surface Dirac cones is given by a new topological invariant\ndetermined from the scattering matrix of the system. Further, we find that due\nto particle-hole symmetry, the positions of Dirac cones in the surface\nBrillouin zone are controlled by an additional invariant, counting the parity\nof modes present at high symmetry points."
    },
    {
        "anchor": "On simulation of local fluxes in molecular junctions: We present a pedagogical review of current density simulation in molecular\njunction models indicating its advantages and deficiencies in analysis of local\njunction transport characteristics. In particular, we argue that current\ndensity is a universal tool which provides more information than traditionally\nsimulated bond currents, especially when discussing inelastic processes.\nHowever, current density simulations are sensitive to choice of basis and\nelectronic structure method. We note that discussing local current conservation\nin junctions one has to account for source term caused by open character of the\nsystem and intra-molecular interactions. Our considerations are illustrated\nwith numerical simulations of a benzenedithiol molecular junction.",
        "positive": "Twisting enabled charge transfer excitons in epitaxially fused quantum\n  dot molecules: Charge-transfer excitons possessing long radiative lifetime and net permanent\ndipole moment are highly appealing for quantum dot (QD) based energy harvesting\nand photodetecting devices, in which the efficiency of charge separation after\nphoto-excitation limits the device performance. Herein, using a hybrid\ntime-dependent density functional theory, we have demonstrated that the\nprevailing rule of selecting materials with staggered type-II band alignment\nfor realization of charge-transfer exciton breaks down in epitaxially fused QD\nmolecules. The excitonic many-body effects are found to be significant and\ndistinct depending on the exciton nature, causing unexpected reverse ordering\nof exciton states. Strikingly, twisting QD molecule appears as an effective\nmeans of modulating the orbital spatial localization towards charge separation\nthat is mandatory for a charge-transfer exciton. Meanwhile, it manifests the\nintra-energy-level splitting that counterbalances the distinct many-body\neffects felt by excitons of different nature, thus ensuring the successful\ngeneration of energetically favourable charge-transfer exciton in both\nhomodimer and heterodimer QD molecules. Our study extends the realm of\ntwistroincs into zero-dimensional materials, and provides a genuine route of\nmanipulating the exciton nature in QD molecules."
    },
    {
        "anchor": "Gate-tuned Aharonov-Bohm interference of surface states in a\n  quasi-ballistic Dirac semimetal nanowire: We report an observation of a topologically protected transport of surface\ncarriers in a quasi-ballistic Cd3As2 nanowire.The nanowire is thin enough for\nthe spin-textured surface carriers to form 1D subbands, demonstrating\nconductance oscillations with gate voltage even without magnetic field. The\n{\\pi} phase-shift of Aharonov-Bohm oscillations can periodically appear or\ndisappear by tuning gate voltage continuously. Such a {\\pi} phase shift\nstemming from the Berry's phase demonstrates the topological nature of surface\nstates.The topologically protected transport of the surface states is further\nrevealed by four-terminal nonlocal measurements.",
        "positive": "Perturbation study of the conductance through a finite Hubbard chain: Transport through a Hubbard chain of size N (=1,2,3,...) connected to\nreservoirs is studied at T = 0 in an electron-hole symmetric case based on the\nsecond-order perturbation theory in U. The result shows a typical even-odd\nproperty corresponding to a Kondo or Mott-Hubbard physics. In this report,\nspecifically, we study the dependence of the conductance on the coupling\nbetween the chain and reservoirs, which was not examined in detail in our\nprevious report [Phy. Rev. B 59, 12240 (1999)]."
    },
    {
        "anchor": "Terahertz surface plasmons in optically pumped graphene structures: We analyze the surface plasmons (SPs) propagating along the optically pumped\nsingle-graphene layer (SGL) and multiple-graphene layer (MGL) structures. It is\nshown that at sufficiently strong optical pumping when the real part of dynamic\nconductivity of SGL and MGL structures becomes negative in the terahertz (THz)\nrange of frequencies due to the interband population inversion, the damping of\nthe THz SPs can give way to their amplification. This effect can be used in\ngraphene-based THz lasers and other devices. Due to relatively small SP group\nvelocity, the absolute value of their absorption coefficient (SP gain) can be\nlarge, substantially exceeding that of the optically pumped structures with the\ndielectric waveguide. The comparison of the SGL and MGL structures shows that\nto maximize the SP gain the number of GL layers should be properly choosen.",
        "positive": "Frequency-dependent current correlation functions from scattering theory: We present a general formalism based on scattering theory to calculate\nquantum correlation functions involving several time-dependent current\noperators. A key ingredient is the causality of the scattering matrix, which\nallows one to deal with arbitrary correlation functions. Our formalism might be\nuseful in view of recent developments in full counting statistics of charge\ntransfer, where detecting schemes have been proposed for measurement of\nfrequency dependent spectra of higher moments. Some of these schemes are\ndifferent from the well-known fictitious spin-detector and therefore generally\ninvolve calculation of non-Keldysh-contour-ordered correlation functions. As an\nillustration of our method we consider various third order correlation\nfunctions of current, including the usual third cumulant of current statistics.\nWe investigate the frequency dependence of these correlation functions\nexplicitly in the case of energy-independent scattering. The results can easily\nbe generalized to the calculation of arbitrary n-th order correlation\nfunctions, or to include the effect of interactions."
    },
    {
        "anchor": "Fractional Quantum Hall Effect and vortex lattices.II: It is demonstrated that all observed fractions at moderate Landau level\nfillings for the quantum Hall effect can be obtained without recourse to the\nphenomenological concept of composite fermions. The possibility to have the\nspecial topologically nontrivial many-electron wave functions is considered.\nTheir group classification indicates the special values of of electron density\nin the ground states separated by a gap from excited states. These gaps were\ncalculated for some lattices in a simplified model.",
        "positive": "Conductance of Atomic-Sized Lead Contacts in an Electrochemical\n  Environment: Atomic-sized lead (Pb) contacts are deposited and dissolved in an\nelectrochemical environment, and their transport properties are measured. Due\nto the electrochemical fabrication process, we obtain mechanically unstrained\ncontacts and conductance histograms with sharply resolved, individual peaks.\nCharge transport calculations based on density functional theory (DFT) for\nvarious ideal Pb contact geometries are in good agreement with the experimental\nresults. Depending on the atomic configuration, single-atom-wide contacts of\none and the same metal yield very different conductance values."
    },
    {
        "anchor": "Numerically efficient density-matrix technique for modeling electronic\n  transport in midinfrared quantum cascade lasers: We present a numerically efficient density-matrix model applicable to\nmidinfrared quantum cascade lasers. The model is based on a Markovian master\nequation for the density matrix that includes in-plane dynamics, preserves\npositivity of the density matrix and does not rely on phenomenologically\nintroduced dephasing times. Nonparabolicity in the bandstructure is accounted\nfor with a three-band k.p model, which includes the conduction, light-hole, and\nspin-orbit split-off bands. We compare the model to experimental results for\nQCLs based on lattice-matched as well as strain-balanced InGaAs/InAlAs\nheterostructures grown on InP. We find that our density-matrix model is in\nquantitative agreement with experiment up to threshold and is capable of\nreproducing results obtained using the more computationally expensive\nnonequilibrium Green's function formalism. We compare our density-matrix model\nto a semiclassical model where off-diagonal elements of the density matrix are\nignored. We find that the semiclassical model overestimates the threshold\ncurrent density by 29% for a 8.5-um QCL based on a lattice-matched\nheterostructure and 40% for a 4.6-um QCL based on a strain-balanced\nheterostructure, demonstrating the need to include off diagonal density matrix\nelements for accurate description of midinfrared QCLs.",
        "positive": "Revisit the spin-FET: Multiple reflections, inelastic scattering, and\n  lateral size effects: We revisit the spin-injected field effect transistor (spin-FET) by simulating\na lattice model based on recursive lattice Green's function approach. In the\none-dimensional case and coherent regime, the simulated results reveal\nnoticeable differences from the celebrated Datta-Das model, which motivate thus\nan improved treatment and lead to analytic and generalized result. The\nsimulation also allows us to address inelastic scattering (using B\\\"uttiker's\nfictitious reservoir approach) and lateral confinement effects on the control\nof spins which are important issues in the spin-FET device."
    },
    {
        "anchor": "Supercurrent decay in ballistic magnetic Josephson junctions: We investigate transport properties of ballistic magnetic Josephson junctions\nand establish that suppression of supercurrent is an intrinsic property of the\njunctions, even in absence of disorder. By studying the role of ferromagnet\nthickness, magnetization, and crystal orientation we show how the supercurrent\ndecays exponentially with thickness and identify two mechanisms responsible for\nthe effect: (i) large exchange splitting may gap out minority or majority\ncarriers leading to the suppression of Andreev reflection in the junction, (ii)\nloss of synchronization between different modes due to the significant\ndispersion of the quasiparticle velocity with the transverse momentum. Our\nresults for Nb/Ni/Nb junctions are in good agreement with recent experimental\nstudies. Our approach combines density functional theory and Bogoliubov-de\nGennes model and opens a path for material composition optimization in magnetic\nJosephson junctions and superconducting magnetic spin valves.",
        "positive": "Evanescently coupled topological ring-waveguide systems for chip-scale\n  ultrahigh frequency phononic circuits: Topological phononics enabling backscattering-immune transport is expected to\nimprove the performance of electromechanical systems for classical and quantum\ninformation technologies. Nonetheless, most of the previous demonstrations\nutilized macroscale and low-frequency structures and thus offered little\nexperimental insight into ultrahigh frequency phonon transport, especially in\nchip-scale circuits. Here, we report microwave phonon transmissions in a\nmicroscopic topological ring-waveguide coupled system, which is an important\nbuilding block for wave-based signal processing. The elastic waves in the\ntopological waveguide evanescently couple to the ring resonator, while\nmaintaining the valley pseudospin polarization. The resultant waves are robust\nto backscattering even in the tiny hexagonal ring, generating a resonant phonon\ncirculation. Furthermore, the evanescently coupled structure allows for a\ncritical coupling, where valley-dependent ring-waveguide interference enables\nblocking of the topological edge transmission. Our demonstrations reveal the\ncapability of using topological phenomena to manipulate ultrahigh frequency\nelastic waves in intricate phononic circuits for classical and quantum\nsignal-processing applications."
    },
    {
        "anchor": "Measuring anisotropic spin relaxation in graphene: We compare different methods to measure the anisotropy of the spin-lifetime\nin graphene. In addition to out-of-plane rotation of the ferromagnetic\nelectrodes and oblique spin precession, we present a Hanle experiment where the\nelectron spins precess around either a magnetic field perpendicular to the\ngraphene plane or around an in-plane field. In the latter case, electrons are\nsubject to both in-plane and out-of-plane spin relaxation. To fit the data, we\nuse a numerical simulation that can calculate precession with anisotropies in\nthe spin-lifetimes under magnetic fields in any direction. Our data show a\nsmall, but distinct anisotropy that can be explained by the combined action of\nisotropic mechanisms, such as relaxation by the contacts and resonant\nscattering by magnetic impurities, and an anisotropic Rashba spin-orbit based\nmechanism. We also assess potential sources of error in all three types of\nexperiment and conclude that the in-plane/out-of-plane Hanle method is most\nreliable.",
        "positive": "Structure-imposed electronic topology in cove-edged graphene nanoribbons: In cove-edged zigzag graphene nanoribbons (ZGNR-C), one terminal CH group per\nlength unit is removed on each zigzag edge, forming a regular pattern of coves\nwhich controls their electronic structure. Based on three structural parameters\nthat unambiguously characterize the atomistic structure of ZGNR-C, we present a\nscheme that classifies their electronic state, i.e., if they are metallic,\ntopological insulators or trivial semiconductors, for all possible widths N,\nunit lengths a and cove position offsets at both edges b, thus showing the\ndirect structure-electronic structure relation. We further present an empirical\nformula to estimate the band gap of the semiconducting ribbons from N, a, and\nb. Finally, we identify all geometrically possible ribbon terminations and\nprovide rules to construct ZGNR-C with well-defined electronic structure."
    },
    {
        "anchor": "Acoustic Phonon Tunneling and Heat Transport due to Evanescent Electric\n  Fields: The authors describe how acoustic phonons can directly tunnel through vacuum\nand, therefore, transmit energy and conduct heat between bodies that are\nseparated by a vacuum gap. This effect is enabled by introducing a coupling\nmechanism, such as piezoelectricity, that strongly couples electric field and\nlattice deformation. The electric field leaks into the vacuum as an evanescent\nfield, which leads to finite solid-vacuum-solid transmission probability. Due\nto strong resonances in the system some phonons can go through the vacuum gap\nwith (or close to) unity transmission, which leads to significant thermal\nconductance and heat flux.",
        "positive": "Highly Tunable Ground and Excited State Excitonic Dipoles in Multilayer\n  2H-MoSe$_2$: The fundamental properties of an exciton are determined by the spin, valley,\nenergy, and spatial wavefunctions of the Coulomb bound electron and hole. In\nvan der Waals materials, these attributes can be widely engineered through\nlayer stacking configuration to create highly tunable interlayer excitons with\nstatic out-of-plane electric dipoles, at the expense of the strength of the\noscillating in-plane dipole responsible for light-matter coupling. Here we show\nthat interlayer excitons in bi- and tri-layer 2H-MoSe$_2$ crystals exhibit\nelectric-field-driven coupling with the ground ($1s$) and excited states ($2s$)\nof the intralayer A excitons. We demonstrate that the hybrid states of these\ndistinct exciton species provide strong oscillator strength, large permanent\ndipoles (up to $0.73 \\pm 0.01$ enm), high energy tunability (up to $\\sim$ 200\nmeV), and full control of the spin and valley characteristics such that the\nexciton g-factor can be manipulated over a large range (from -4 to +14).\nFurther, we observe the bi- and tri-layer excited state ($2s$) interlayer\nexcitons and their coupling with the intralayer excitons states ($1s$ and\n$2s$). Our results, in good agreement with a coupled oscillator model with spin\n(layer)-selectivity and beyond standard density functional theory calculations,\npromote multilayer 2H-MoSe$_2$ as a highly tunable platform to explore\nexciton-exciton interactions with strong light-matter interactions."
    },
    {
        "anchor": "Optimal quantum control in nanostructures: Theory and application to\n  generic three-level system: Coherent carrier control in quantum nanostructures is studied within the\nframework of Optimal Control. We develop a general solution scheme for the\noptimization of an external control (e.g., lasers pulses), which allows to\nchannel the system's wavefunction between two given states in its most\nefficient way; physically motivated constraints, such as limited laser\nresources or population suppression of certain states, can be accounted for\nthrough a general cost functional. Using a generic three-level scheme for the\nquantum system, we demonstrate the applicability of our approach and identify\nthe pertinent calculation and convergence parameters.",
        "positive": "Role of Phonon Scattering in Graphene Nanoribbon Transistors:\n  Non-Equilibrium Green's Function Method with Real Space Approach: Mode space approach has been used so far in NEGF to treat phonon scattering\nfor computational efficiency. Here we perform a more rigorous quantum transport\nsimulation in real space to consider interband scatterings as well. We show a\nseamless transition from ballistic to dissipative transport in graphene\nnanoribbon transistors by varying channel length. We find acoustic phonon (AP)\nscattering to be the dominant scattering mechanism within the relevant range of\nvoltage bias. Optical phonon scattering is significant only when a large gate\nvoltage is applied. In a longer channel device, the contribution of AP\nscattering to the dc current becomes more significant."
    },
    {
        "anchor": "Massless Dirac-like fermions under external fields: a nonminimal\n  coupling approach: We investigate the unusual properties of quasirelativistic massless fermions\nunder a magnetic or electric field by means of nonminimal couplings. Within\nthis approach, the spin-orbit coupling (SOC) effects are properly generated in\nthe energy spectrum of the quasiparticles. By including a magnetic field, $B$,\nwe show that the spin splitting of Landau Levels (LL) obeys a $\\sqrt{B}$ linear\ndependence with SOC, typical of relativistic particles. Moreover, our\ncalculated spectrum of LLs resembles the behavior of the three-dimensional (3D)\nmassless Kane fermions. Using a nonminimal coupling with an external electric\nfield, we demonstrate that a Rashba-like SOC naturally appears into the\nrelativistic equations and apply to the case of two-dimensional (2D) massless\nDirac fermions. Still considering our proposed approach, the Hall conductivity\nis also computed for the 2D case under transverse electric field both at zero\nand finite temperatures for a general chemical potential. The results feature a\ntypical quantization of the Hall conductivity at low temperatures, when the\nabsolute value of the gap opened by the electric field is larger than the\nconsidered chemical potential.",
        "positive": "Anisotropic plasmon-coupling dimerization of a pair of spherical\n  electron gases: We have discovered a novel feature in the plasmon excitations for a pair of\nCoulomb-coupled non- concentric spherical two-dimensional electron gases\n(S2DEGs). Our results show that the plasmon excitations for such pairs depend\non the orientation with respect to the external electromagnetic probe field.\nThe origin of this anisotropy of the inter-sphere Coulomb interaction is due to\nthe directional asymmetry of the electrostatic coupling of electrons in excited\nstates which depend on both the angular momentum quantum number L and its\nprojection M on the axis of quantization taken as the probe E-field direction.\nWe demonstrate the anisotropic inter-sphere Coulomb coupling in space and\npresent semi-analytic results in the random-phase approximation both\nperpendicular and parallel to the axis of quantization. For the incidence of\nlight with a finite orbital or spin angular momentum, the magnetic field\ngenerated from an induced oscillating electric dipole on one sphere can couple\nto an induced magnetic dipole on another sphere in a way depending on the\ndirection parallel or perpendicular to the probe E field. Such an effect from\nthe plasmon spatial correlation is expected to be experimentally observable by\nemploying circularly-polarized light or a helical light beam for incidence. The\nS2DEG serves as a simple model for fullerenes as well as metallic dimers, when\nthe energy bands are far apart."
    },
    {
        "anchor": "$\\mathbb Z_2$~Green's function topology of Majorana wires: We represent the $\\mathbb Z_2$~topological invariant characterizing a one\ndimensional topological superconductor using a Wess-Zumino-Witten dimensional\nextension. The invariant is formulated in terms of the single particle Green's\nfunction which allows to classify interacting systems. Employing a recently\nproposed generalized Berry curvature method, the topological invariant is\nrepresented independent of the extra dimension requiring only the single\nparticle Green's function at zero frequency of the interacting system.\nFurthermore, a modified twisted boundary conditions approach is used to\nrigorously define the topological invariant for disordered interacting systems.",
        "positive": "Current Streamline Flow on Current-induced Effects in Highly Asymmetric\n  Molecular Junctions: From first-principles approaches, we illustrate that the current-induced\nforces and the selection rule for inelastic effects are highly relevant to the\ncurrent density in an asymmetric molecular junction. The curved flow of current\nstreamline around the asymmetric molecule may induce a net torque, which tends\nto rotate the benzene molecule, similar to the way a stream of water rotates a\nwaterwheel. Thus, the Pt/benzene junction offers a practical system in the\nexploration of the possibility of atomic-scale motors. We also enumerate\nexamples to show that the use of selection rule can lead to misjudgement of the\nimportance of normal modes in the inelastic profiles when the detailed\ninformation about the current density is not considered."
    },
    {
        "anchor": "Atomic Resolution Imaging of Currents in Nanoscopic Quantum Networks via\n  Scanning Tunneling Microscopy: We propose a new method for atomic-scale imaging of spatial current patterns\nin nanoscopic quantum networks by using scanning tunneling microscopy (STM). By\nmeasuring the current flowing from the STM tip into one of the leads attached\nto the network as a function of tip position, one obtains an atomically\nresolved spatial image of \"current riverbeds\" whose spatial structure reflects\nthe coherent flow of electrons out of equilibrium. We show that this method can\nbe successfully applied in variety of network topologies, and is robust against\ndephasing effects.",
        "positive": "A quantum pseudodot system with two-dimensional pseudoharmonic potential\n  under external magnetic and AB flux fields: Using the Nikiforov-Uvarov (NU) method, the energy levels and the wave\nfunctions of an electron confined in a two-dimensional (2D) pseudoharmonic\nquantum dot are calculated under the influence of temperature and an external\nmagnetic field inside dot and Aharonov-Bohm (AB) field inside a pseudodot.\nmagnetic field and geometrical size of quantum pseudodot. The temperature\ndependence energy levels for GaAs semiconductor are also calculated. The exact\nsolutions for energy eigenvalues and wave functions are computed as functions\nof the chemical potential parameters, applied magnetic field strength, AB flux\nfield, magnetic quantum number and temperature. Analytical expression for the\nlight interband absorption coefficient and absorption threshold frequency are\nfound as functions of applied"
    },
    {
        "anchor": "Polarization in quasirelativistic graphene model with topologically\n  non-trivial charge carriers: Within the earlier developed high-energy-$\\vec k\\cdot \\vec p$-Hamiltonian\napproach to describe graphene-like materials, the simulations of band\nstructure, non-Abelian Zak phases and complex conductivity of graphene have\nbeen performed. The quasi-relativistic graphene model with a number of flavors\n(gauge fields) $N_F=3$ in two approximations (with and without a\npseudo-Majorana mass term) has been utilized as a ground for the simulations.\nIt has been shown that a Zak-phases set for the non-Abelian Majorana-like\nexcitations (modes) in graphene is the cyclic group $\\mathbf{Z}_{12}$ and this\ngroup is deformed into a smaller one $\\mathbf{Z}_8$ at sufficiently high\nmomenta due to a deconfinement of the modes. Simulations of complex\nlongitudinal low-frequency conductivity have been performed with focus on\neffects of spatial dispersion. The spatial periodic polarization in the\ngraphene models with the pseudo Majorana charge carriers is offered.",
        "positive": "Dynamics of formation and decay of coherence in a polariton condensate: We study the dynamics of formation and decay of a condensate of microcavity\npolaritons. We investigate the relationship between the number of particles,\nthe emission's linewidth and its degree of linear polarization which serves as\nthe order parameter. Tracking the condensate's formation, we show that, even\nwhen interactions are negligible, coherence is not determined only by\noccupation of the ground state. As a result of the competition between the\ncoherent and thermal fractions of the condensate, the highest coherence is\nobtained some time after the particle number has reached its maximum."
    },
    {
        "anchor": "Topological enhancement of exciton-polariton coherence with\n  non-Hermitian morphing: The non-Hermitian skin effect (NHSE) has been intensely investigated over the\npast few years and has unveiled new topological phases, which have no\ncounterparts in Hermitian systems. Here we consider the hybridization between\nthe NHSE in an exciton-polariton waveguide and a localized defect mode. By\ntuning the non-Hermiticity, we find that the resulting ground-state of the\nsystem is both spatially extended and energetically separated from other modes\nin the system. When polariton lasing occurs in the system, we find an enhanced\nspatial coherence compared to regular waveguides, which is robust in the\npresence of disorder.",
        "positive": "Upwind exciton-polariton propagation in hybrid photonic crystals: In this work we study theoretically the axial spectral asymmetry of a 1D\nperiodic multilayer systems composed by hybrid two-layers\n(isotropic/anisotropic) and for photon energies close to the electronic energy\ngaps of semiconductors (excitons). The non-normal optical properties of these\nresonant non-magnetic photonic crystals, where linear and quadratic spatial\ndispersion effects are both present, will be computed in the framework of\nexciton-polariton by self-consistent Maxwell-Schroedinger equation solutions in\nthe effective mass approximation. The tailoring of hybrid crystal, where\nexciton-polariton unidirectional oblique propagation is observed, will be\ncomputed by implementing a simple two-layers minimum model."
    },
    {
        "anchor": "Undamped inter-valley paramagnons in doped graphene: We predict the existence of an undamped collective spin excitation in doped\ngraphene in the paramagnetic regime, referred to as paramagnons. Since the\nelectrons and the holes involved in this collective mode reside in different\nvalleys of the band structure, the momentum of these inter-valley paramagnons\nis given by the separation of the valleys in momentum space. The energy of the\ninter-valley paramagnons lies in the void region below the continuum of\ninter-band single-particle electron-hole excitations that appears when graphene\nis doped. The paramagnons are undamped due to the lack of electron-hole\nexcitations in this void region. Their energy strongly depends on doping\nconcentration, which can help to identify them in future experiments.",
        "positive": "Classical Quantization of Local Hall Conductivity in 2D Ballistic\n  Systems: We study the linear Hall response of 2D ballistic system on inhomogeneous\nmagnetic field. We establish that in classical limit the Hall conductivity\nresponse on local magnetic field is quantized in units of $\\alpha_H \\equiv\n\\frac{e^3}{2 \\pi^2 \\hbar c}$. The quantized value depends on the point where\nthe field is applied, this dependence being irregular in chaotic billiards. The\nphenomenon allows for direct tracing of special electron trajectories that\nbelong to fractal repellor. We discuss how quantum effects smooth the\nquantization."
    },
    {
        "anchor": "The Core Diffusion-Drift Field-Effect Transistor Theory Including\n  Quantum and Interface Trap Capacitances: We have decomposed the modeling of the field-effect transistors into the two\nindependent parts: the current continuity based kinetics and the charge\nneutrality based electrostatics. The former part, that is universal for all\nFETs, leads to an explicit and closed form of I-V characteristics as a function\nof the total channel charge. The latter part, which is specific for a\nparticular material and geometric configurations can be considered as an\nindependent engineering task. The quantum capacitance and the interface trap\ndensity are consistently incorporated into the solution of the current\ncontinuity equation in the diffusion-drift approximation, providing a complete\nconsistency in the current and the capacitance small-signal characteristics.",
        "positive": "Graphene nanoribbons subject to gentle bends: Since graphene nanoribbons are thin and flimsy, they need support. Support\ngives firm ground for applications, and adhesion holds ribbons flat, although\nnot necessarily straight: ribbons with high aspect ratio are prone to bend. The\neffects of bending on ribbons' electronic properties, however, are unknown.\nTherefore, this article examines the electromechanics of planar and gently bent\ngraphene nanoribbons. Simulations with density-functional tight-binding and\nrevised periodic boundary conditions show that gentle bends in armchair ribbons\ncan cause significant widening or narrowing of energy gaps. Moreover, in zigzag\nribbons sizeable energy gaps can be opened due to axial symmetry breaking, even\nwithout magnetism. These results infer that, in the electronic measurements of\nsupported ribbons, such bends must be heeded."
    },
    {
        "anchor": "Statistical electron excitation in a double quantum dot induced by two\n  independent quantum point contacts: We investigate experimentally the influence of current flow through two\nindependent quantum point contacts to a nearby double quantum dot realized in a\nGaAs-AlGaAs heterostructure. The observed current through the double quantum\ndot can be explained in terms of coupling to a bosonic bath. The temperature of\nthe bath depends on the power generated by the current flow through the quantum\npoint contact. We identify the dominant absorption and emission mechanisms in a\ndouble quantum dot as an interaction with acoustic phonons. The experiment\nexcludes coupling of a double quantum dot to shot noise generated by quantum\npoint contact as the dominant mechanism.",
        "positive": "The Behavior of Electronic Interferometers in the Non-Linear Regime: We investigate theoretically the behavior of the current oscillations in an\nelectronic Mach-Zehnder interferometer (MZI) as a function of its source bias.\nRecently, The MZI interference visibility showed an unexplained lobe pattern\nbehavior with a peculiar phase rigidity. Moreover, the effect did not depend on\nthe MZI paths difference. We argue that these effects may be a new many-body\nmanifestation of particle-wave duality of quantum mechanics. When biasing the\ninterferometer sources beyond the linear response regime, quantum shot-noise (a\nparticle phenomena) must affect the interference pattern of the electrons that\ncreates it, as a result from a simple invariance argument. An approximate\nsolution of the interacting Hamiltonian indeed shows that the interference\nvisibility has a lobe pattern with applied bias with a period proportional to\nthe average path length and independent of the paths difference, together with\na phase rigidity."
    },
    {
        "anchor": "Exactly Soluble Model for Umklapp Scattering at Quantum-Hall Edges: We consider the low-energy, long-wave-length excitations of a reconstructed\nquantum-Hall edge where three branches of chiral one-dimensional edge\nexcitations exist. We find that, in addition to forward scattering between the\nthree edge-excitation branches, Coulomb interaction gives rise to a novel\nUmklapp-type scattering process that cannot be accounted for within a\ngeneralized Tomonaga-Luttinger model. We solve the theory including Umklapp\nprocesses exactly in the long-wave-length limit and calculate electronic\ncorrelation functions.",
        "positive": "Probing spatial extent of topological surface states by weak\n  antilocalization experiments: Weak antilocalization measurements has become a standard tool for studying\nquantum coherent transport in topological materials. It is often used to\nextract information about number of conducting channels and dephasing length of\ntopological surface states. We study thin films of prototypical topological\ncrystalline insulator SnTe. To access microscopic characteristic of these\nstates we employ a model developed by Tkachov and Hankiewicz, [Physical Review\nB 84, 035444]. Using this model the spatial decay of the topological states is\nobtained from measurements of quantum corrections to the conductivity in\nperpendicular and parallel configurations of the magnetic field. Within this\nmodel we find interaction between two topological boundaries which results in\nscaling of the spatial decay with the film thickness. We attribute this\nbehavior to bulk reservoir which mediates interactions by scattering events\nwithout phase breaking of topological carriers."
    },
    {
        "anchor": "Odd integer quantum Hall effect in graphene: A possible realization of Hall conductivity, quantized at odd integer factors\nof $e^2/h$ for graphene's honeycomb lattice is proposed. I argue that, in the\npresence of \\emph{uniform} real and pseudo-magnetic fields, the valley\ndegeneracy from the higher Landau levels can be removed. A pseudo-magnetic\nfield may arise from bulging or stretching of the graphene flake. This may lead\nto observation of plateaus in the Hall conductivity at quantized values $f\ne^2/h$, with $f=\\pm 3, \\pm 5$ etc, which have not been observed in measurement\nof Hall conductivity. However, in a collection of noninteracting Dirac fermions\nliving in the honeycomb lattice subject to real and pseudo field, the zeroth\nLandau level still enjoys the valley and the spin degeneracy. Upon including\nthe Zeeman coupling, the spin degeneracy is removed from all the Landau levels.\nThe effects of short ranged electron-electron interactions are also considered,\nparticularly, the onsite Hubbard repulsion (U) and the nearest-neighbor Coulomb\nrepulsion (V). Within the framework of the extended Hubbard model with only\nthose two components of finite ranged Coulomb repulsion, it is shown that\ninfinitesimally weak interactions can place the system in a gapped insulating\nphase by developing a \\emph{ferrimegnatic} order, if $U>>V$. Therefore, one may\nexpect to see the plateaus in the Hall conductivity at all the integer values,\n$f=0,\\pm 1,\\pm 2, \\pm3,...$. Scaling behavior of interaction induced gap at\n$f=1$ in presence of finite pseudo flux is also addressed. Qualitative\ndiscussion on finite size effects and behavior of the interaction induced gap\nwhen the restriction on uniformity of the fields are relaxed, is presented as\nwell. Possible experimental set up that can test relevance of our theory has\nbeen proposed.",
        "positive": "An analysis of reading out the state of a charge quantum bit: We provide a unified picture for the master equation approach and the quantum\ntrajectory approach to a measurement problem of a two-state quantum system (a\nqubit), an electron coherently tunneling between two coupled quantum dots\n(CQD's) measured by a low transparency point contact (PC) detector. We show\nthat the master equation of ``partially'' reduced density matrix can be derived\nfrom the quantum trajectory equation (stochastic master equation) by simply\ntaking a ``partial'' average over the all possible outcomes of the measurement.\nIf a full ensemble average is taken, the traditional (unconditional) master\nequation of reduced density matrix is then obtained. This unified picture, in\nterms of averaging over (tracing out) different amount of detection records\n(detector states), for these seemingly different approaches reported in the\nliterature is particularly easy to understand using our formalism. To further\ndemonstrate this connection, we analyze an important ensemble quantity for an\ninitial qubit state readout experiment, $P(N,t)$, the probability distribution\nof finding $N$ electrons that have tunneled through the PC barrier in time $t$.\nThe simulation results of $P(N,t)$ using 10000 quantum trajectories and\ncorresponding measurement records are, as expected, in very good agreement with\nthose obtained from the Fourier analysis of the ``partially'' reduced density\nmatrix. However, the quantum trajectory approach provides more information and\nmore physical insights into the ensemble and time averaged quantity $P(N,t)$.\nEach quantum trajectory resembles a single history of the qubit state in a\nsingle run of the continuous measurement experiment. We finally discuss, in\nthis approach, the possibility of reading out the state of the qubit system in\na single-shot experiment."
    },
    {
        "anchor": "Complex band structure and electronic transmission: The function of nano-scale devices critically depends on the choice of\nmaterials. For electron transport junctions it is natural to characterize the\nmaterials by their conductance length dependence, $\\beta$. Theoretical\nestimations of $\\beta$ are made employing two primary theories: complex band\nstructure and DFT-NEGF Landauer transport. Both reveal information on $\\beta$\nof individual states; i.e. complex Bloch waves and transmission eigenchannels,\nrespectively. However, it is unclear how the $\\beta$-values of the two\napproaches compare. Here, we present calculations of decay constants for the\ntwo most conductive states as determined by complex band structure and standard\nDFT-NEGF transport calculations for two molecular and one semi-conductor\njunctions. Despite the different nature of the two methods, we find strong\nagreement of the calculated decay constants for the molecular junctions while\nthe semi-conductor junction shows some discrepancies. The results presented\nhere provide a template for studying the intrinsic, channel resolved length\ndependence of the junction through complex band structure of the central\nmaterial in the heterogeneous nano-scale junction.",
        "positive": "Fermi-liquid effects in the transresistivity in quantum Hall double\n  layers near $\u03bd= 1/2 $: Here, we present theoretical studies of the temperature and magnetic field\ndependences of the Coulomb drag transresistivity between two parallel layers of\ntwo dimensional electron gases in quantum Hall regime near half filling of the\nlowest Landau level. It is shown that Fermi-liquid interactions between the\nrelevant quasiparticles could give a significant effect on the\ntransresistivity, providing its independence of the interlayer spacing for\nspacings taking on values reported in the experiments. Obtained results agree\nwith the experimental evidence."
    },
    {
        "anchor": "Theory of one and two donors in Silicon: We provide here a roadmap for modeling silicon nano-devices with one or two\ngroup V donors (D). We discuss systems containing one or two electrons, that\nis, D^0, D^-, D_2^+ and D_2^0 centers. The impact of different levels of\napproximation is discussed. The most accurate instances -- for which we provide\nquantitative results -- are within multivalley effective mass including the\ncentral cell correction and a configuration interaction account of the\nelectron-electron correlations. We also derive insightful, yet less accurate,\nanalytical approximations and discuss their validity and limitations -- in\nparticular, for a donor pair, we discuss the single orbital LCAO method, the\nHuckel approximation and the Hubbard model. Finally we discuss the connection\nbetween these results and recent experiments on few dopant devices.",
        "positive": "Decoherence-protected quantum gates for a hybrid solid-state spin\n  register: Protecting the dynamics of coupled quantum systems from decoherence by the\nenvironment is a key challenge for solid-state quantum information processing.\nAn idle qubit can be efficiently insulated from the outside world via dynamical\ndecoupling, as has recently been demonstrated for individual solid-state\nqubits. However, protection of qubit coherence during a multi-qubit gate poses\na non-trivial problem: in general the decoupling disrupts the inter-qubit\ndynamics, and hence conflicts with gate operation. This problem is particularly\nsalient for hybrid systems, wherein different types of qubits evolve and\ndecohere at vastly different rates. Here we present the integration of\ndynamical decoupling into quantum gates for a paradigmatic hybrid system, the\nelectron-nuclear spin register. Our design harnesses the internal resonance in\nthe coupled-spin system to resolve the conflict between gate operation and\ndecoupling. We experimentally demonstrate these gates on a two-qubit register\nin diamond operating at room temperature. Quantum tomography reveals that the\nqubits involved in the gate operation are protected as accurately as idle\nqubits. We further illustrate the power of our design by executing Grover's\nquantum search algorithm, achieving fidelities above 90% even though the\nexecution time exceeds the electron spin dephasing time by two orders of\nmagnitude. Our results directly enable decoherence-protected interface gates\nbetween different types of promising solid-state qubits. Ultimately, quantum\ngates with integrated decoupling may enable reaching the accuracy threshold for\nfault-tolerant quantum information processing with solid-state devices."
    },
    {
        "anchor": "Possibility of magnetic field induced Composite Fermi sea in neutral\n  Graphene: Neutral graphene in strong magnetic fields is believed to be an (exchange\nstabilized) integer Hall state of completely filled up spin (say) and empty\ndown spin bands of n = 0, two fold valley degenerate Landau levels. We suggest\nthat correlation energy gain from a nearly SU(4) singlet (2 spin $\\times$ 2\nvalley) composite fermi sea formation, at $\\nu \\approx$ \\hlf filling for each\ncomponent, destabilizes ferromagnetic integer quantum Hall state. This\nradically different scenario is consistent with a dissipative gapless state\nseen in experiments in neutral graphene. Interesting paired Hall states are\npossible, from residual interactions, in this SU(4) fermi sea with a small\nZeeman spin polarization.",
        "positive": "Electronic thermal conductivity of disordered metals: We calculate the thermal conductivity of interacting electrons in disordered\nmetals. In our analysis we point out that the interaction affects thermal\ntransport through two distinct mechanims, associated with quantum interference\ncorrections and energy exchange of the quasi particles with the electromagnetic\nenvironment, respectively. The latter is seen to lead to a violation of the\nWiedemann-Franz law. Our theory predicts a strong enhancement of the Lorenz\nratio $\\kappa /\\sigma T$ over the value which is predicted by the\nWiedemann-Franz law, when the electrons encounter a large environmental\nimpedance."
    },
    {
        "anchor": "Transport response of topological hinge modes in $\u03b1$-Bi$_4$Br$_4$: Electronic topological phases are renowned for their unique properties, where\nconducting surface states exist on the boundary of an insulating\nthree-dimensional bulk. While the transport response of the surface states has\nbeen extensively studied, the response of the topological hinge modes remains\nelusive. Here, we investigate a layered topological insulator\n$\\alpha$-Bi$_4$Br$_4$, and provide the first evidence for quantum transport in\ngapless topological hinge states existing within the insulating bulk and\nsurface energy gaps. Our magnetoresistance measurements reveal pronounced h/e\nperiodic (where h denotes Planck's constant and e represents the electron\ncharge) Aharonov-Bohm oscillation. The observed periodicity, which directly\nreflects the enclosed area of phase-coherent electron propagation, matches the\narea enclosed by the sample hinges, providing compelling evidence for the\nquantum interference of electrons circumnavigating around the hinges. Notably,\nthe h/e oscillations evolve as a function of magnetic field orientation,\nfollowing the interference paths along the hinge modes that are allowed by\ntopology and symmetry, and in agreement with the locations of the hinge modes\naccording to our scanning tunneling microscopy images. Remarkably, this\ndemonstration of quantum transport in a topological insulator can be achieved\nusing a flake geometry and we show that it remains robust even at elevated\ntemperatures. Our findings collectively reveal the quantum transport response\nof topological hinge modes with both topological nature and quantum coherence,\nwhich can be directly applied to the development of efficient quantum\nelectronic devices.",
        "positive": "Peculiar Macroscopic And Microscopic Properties Of A Fractional Quantum\n  Hall Layer: At a surface between electromagnetic media the Maxwell equations allow either\nthe usual boundary conditions, or exactly one alternative: continuity of\nE(perpendicular),\n  H(perpendicular), D(parallel), B(parallel). These `flipped' conditions on the\ntop and bottom surfaces of an FQH layer capture all its known static\nelectromagnetic properties and so may be considered a deduction from\nmicroscopic quantum theory, yet are unobtainable in any realistic, purely\nclassical model. An unrealistic model with free magnetic monopole currents\nillustrates this. At the microscopic level, the FQH system is a laboratory for\nthe particle concept. Identifying quasiparticles in terms of kinematics or in\nterms of asymptotic states gives two different perspectives. The kinematics\nexhibits exclusion rules similar to those in exactly solvable models for\nquantum systems in one space dimension. An effort here to tie some of these\naspects together may be useful as a foundation for a future more comprehensive\nassessment of the roles and limitations of quasiparticles."
    },
    {
        "anchor": "z/-z Symmetry of spin-orbit coupling and weak localization in graphene: We show that the influence of spin-orbit (SO) coupling on the weak\nlocalization effect for electrons in graphene depends on the lack or presence\nof z/-z symmetry in the system. While for z/-z asymmetric SO coupling,\ndisordered graphene should display a weak anti-localization behavior at lowest\ntemperature, z/-z symmetric coupling leads to an effective saturation of\ndecoherence time which can be partially lifted by an in-plane magnetic field,\nthus, tending to restore the weak localization effect.",
        "positive": "Anomalous phase shift in a twisted quantum loop: Coherent motion of electrons in a twisted quantum ring is considered to\nexplore the effect of torsion inherent to the ring. Internal torsion of the\nring composed of helical atomic configuration yields a non-trivial quantum\nphase shift in the electrons' eigenstates. This torsion-induced phase shift\ncauses novel kinds of persistent current flow and an Aharonov-Bohm like\nconductance oscillation. The two phenomena can occur even when no magnetic flux\npenetrates inside the twisted ring, thus being in complete contrast with the\ncounterparts observed in untwisted rings."
    },
    {
        "anchor": "Microscopic mechanism of level attraction: The emerging level attraction from dissipative light-matter coupling\nconverges the typical Rabi-splitting feature from coherent coupling and\nexhibits potentials in topological information processing. However, the\nunderlying microscopic quantum mechanism of dissipative coupling still remains\nunclear, which brings difficulties in quantifying and manipulating\ncoherence-dissipation competition and thereby the flexible control of level\nattraction. Here, by coupling magnon to a cavity supporting both standing and\ntravelling waves, we identify the travelling-wave state to be responsible for\nmagnon-photon dissipative coupling. By characterizing radiative broadening of\nmagnon linewidth, we quantify the coherent and dissipative coupling strengths\nand their competition. The effective magnon-photon coupling strength, as a net\nresult of competition, is analytically presented in quantum theory to show good\nagreement with measurements. In this manner, we extend the control dimension of\nlevel attraction by tuning field torque on magnetization or global cavity\ngeometry. Our finding opens new routines to engineer coupled harmonic\noscillator system.",
        "positive": "Characterization of single-molecule pentanedithiol junctions by\n  inelastic electron tunneling spectroscopy and first-principles calculations: We study pentanedithiol molecular junctions formed by means of the\nbreak-junction technique with a scanning tunneling microscope at low\ntemperatures. Using inelastic electron tunneling spectroscopy and\nfirst-principles calculations, the response of the junction to elastic\ndeformation is examined. We show that this procedure makes a detailed\ncharacterization of the molecular junction possible. In particular, our results\nindicate that tunneling takes place through just a single molecule."
    },
    {
        "anchor": "Magnetic anisotropy and chirality of frustrated Cr nanostructures on\n  Au(111): By using a fully relativistic embedded cluster Green's function technique we\ninvestigated the magnetic anisotropy properties of four different compact Cr\ntrimers (equilateral triangles) and Cr mono-layers deposited on Au(111) surface\nin both fcc and hcp stackings. For all trimers the magnetic ground state was\nfound a frustrated 120$^\\circ$ N\\'eel configuration. Applying global spin\nrotations to the magnetic ground state, the predictions of an appropriate\nsecond order spin Hamiltonian were reproduced with high accuracy by the first\nprinciples calculations. For the Cr trimers with adjacent Au atoms in similar\ngeometry we obtained similar values for the in-plane and out-of-plane\nanisotropy parameters, however, the Dzyaloshinskii-Moriya (DM) interactions\nappeared to differ remarkably. For two kinds of trimers we found an\nunconventional magnetic ground state showing 90$^\\circ$ in-the-plane rotation\nwith respect to the high symmetry directions. Due to higher symmetry, the\nin-plane anisotropy term was missing for the mono-layers and distinctly\ndifferent DM interactions were obtained for the different stackings. The chiral\ndegeneracy of the N\\'eel configurations was lifted by less then 2 meV for the\ntrimers, while this value raised up to about 15 meV per 3 Cr atoms for the hcp\npacked mono-layer.",
        "positive": "Fermi surface manipulation by external magnetic field demonstrated for a\n  prototypical ferromagnet: We consider the details of the near-surface electronic band structure of a\nprototypical ferromagnet, Fe(001). Using high resolution angle-resolved\nphotoemission spectroscopy we demonstrate openings of the spin-orbit induced\nelectronic band gaps near the Fermi level. The band gaps and thus the Fermi\nsurface can be manipulated by changing the remanent magnetization direction.\nThe effect is of the order of $\\Delta$E = 100 meV and $\\Delta \\text {k} =\n0.1\\,\\text{\\AA}^{-1}$. We show that the observed dispersions are dominated by\nthe bulk band structure. First-principles calculations and one-step\nphotoemission calculations suggest that the effect is related to changes in the\nelectronic ground state, rather than caused by the photoemission process\nitself. The symmetry of the effect indicates that the observed electronic bulk\nstates are influenced by the presence of the surface, which might be understood\nas related to a Rashba-type effect. By pinpointing the regions in the\nelectronic band structure where the switchable band gaps occur, we demonstrate\nthe significance of spin-orbit interaction even for elements as light as 3d\nferromagnets."
    },
    {
        "anchor": "Cooling electrons from 1 K to 400 mK with V-based nanorefrigerators: The fabrication and operation of V-based superconducting nanorefrigerators is\nreported. Specifically, electrons in an Al island are cooled thanks to\nhot-quasiparticle extraction provided by tunnel-coupled V electrodes.\nElectronic temperature reduction down to 400 mK starting from 1 K is\ndemonstrated with a cooling power ~20 pW at 1 K for a junction area of 0.3\nmicron^2. The present architecture extends to higher temperatures refrigeration\nbased on tunneling between superconductors and paves the way to the\nimplementation of a multi-stage on-chip cooling scheme operating from above 1 K\ndown to the mK regime.",
        "positive": "Validity of kinetic theory for radiative heat transfer in nanoparticle\n  chains: In chains of closely-spaced nanoparticles supporting surface polaritons,\nnear-field electromagnetic coupling leads to collective effects and\nsuper-Planckian thermal radiation exchange. Researchers have primarily used two\nanalytical approaches to calculate radiative heat transfer in these systems:\nfluctuational electrodynamics, which directly incorporates fluctuating thermal\ncurrents into Maxwell's equations, and a kinetic approach where the dispersion\nrelation provides modes and propagation lengths for the Boltzmann transport\nequation. Here, we compare results from the two approaches in order to identify\nregimes in which kinetic theory is valid and to explain differing results in\nthe literature on its validity. Using both methods, we calculate the diffusive\nradiative thermal conductivity of nanoparticle chains. We show that kinetic\ntheory is valid and matches predictions by fluctuational electrodynamics when\nthe propagation lengths are greater than the particle spacing."
    },
    {
        "anchor": "Bose-Einstein condensation in semiconductors: the key role of dark\n  excitons: The non elementary-boson nature of excitons controls Bose-Einstein\ncondensation in semiconductors. Composite excitons interact predominantly\nthrough Pauli exclusion; this produces dramatic couplings between bright and\ndark states. In microcavities, where bright excitons and photons form\npolaritons, they force the condensate to be linearly polarized--as observed. In\nbulk, they also force linear polarization, but of dark states, due to interband\nCoulomb scatterings. To evidence this dark condensate, we thus need indirect\nprocesses, like the shift it induces on the (bright) exciton line.",
        "positive": "Graphene Rings in Magnetic Fields: Aharonov-Bohm Effect and Valley\n  Splitting: We study the conductance of mesoscopic graphene rings in the presence of a\nperpendicular magnetic field by means of numerical calculations based on a\ntight-binding model. First, we consider the magnetoconductance of such rings\nand observe the Aharonov-Bohm effect. We investigate different regimes of the\nmagnetic flux up to the quantum Hall regime, where the Aharonov-Bohm\noscillations are suppressed. Results for both clean (ballistic) and disordered\n(diffusive) rings are presented. Second, we study rings with smooth mass\nboundary that are weakly coupled to leads. We show that the valley degeneracy\nof the eigenstates in closed graphene rings can be lifted by a small magnetic\nflux, and that this lifting can be observed in the transport properties of the\nsystem."
    },
    {
        "anchor": "Local investigation of the energy gap within the incompressible strip in\n  the quantum Hall regime: We experimentally study the energy gap within the incompressible strip at\nlocal filling factor $\\nu_c=1$ at the quantum Hall edge for samples of very\ndifferent mobilities. The obtained results indicate strong enhancement of the\nenergy gap in comparison to the single-particle Zeeman splitting. We identify\nthe measured gap as a mobility gap, so a pronounced experimental in-plane\nmagnetic field dependence can both be attributed to the spin effects as well as\nto the change in the energy levels broadening.",
        "positive": "Multi-mode behavior of electron Zitterbewegung induced by an\n  electromagnetic wave in graphene: Electrons in monolayer graphene in the presence of an electromagnetic (or\nelectric) wave are considered theoretically. It is shown that the electron\nmotion is a nonlinear combination of Zitterbewegung (ZB, trembling motion)\nresulting from the periodic potential of graphene lattice and the driving field\nof the wave. This complex motion is called \"Multi-mode Zitterbewegung\". The\ntheory is based on the time-dependent two-band Hamiltonian taking into account\nthe graphene band structure and interaction with the wave. Our theoretical\ntreatment includes the rotating wave approximation and high-driving-frequency\napproximation for narrow wave packets, as well as numerical calculations for\npackets of arbitrary widths. Different regimes of electron motion are found,\ndepending on relation between the ZB frequency $\\omega_Z$ and the driving\nfrequency $\\omega_D$ for different strengths of the electron-wave interaction.\nFrequencies and intensities of the resulting oscillation modes are calculated.\nThe nonlinearity of the problem results in a pronounced multi-mode behavior.\nPolarization of the medium is also calculated relating our theoretical results\nto observable quantities. The presence of driving wave, resulting in\nfrequencies directly related to $\\omega_Z$ and increasing the decay time of\noscillations, should facilitate observations of the Zitterbewegung phenomenon."
    },
    {
        "anchor": "Sizable spin-transfer torque in Bi/Ni80Fe20 bilayer film: The search for efficient spin conversion in Bi has attracted great attention\nin spin-orbitronics. In the present work, we employ spin-torque ferromagnetic\nresonance to investigate spin conversion in Bi/Ni80Fe20(Py) bilayer films with\ncontinuously varying Bi thickness. In contrast with previous studies, sizable\nspin-transfer torque (i.e., a sizable spin-conversion effect) is observed in\nBi/Py bilayer film. Considering the absence of spin conversion in\nBi/yttrium-iron-garnet bilayers and the enhancement of spin conversion in\nBi-doped Cu, the present results indicate the importance of material\ncombinations to generate substantial spin-conversion effects in Bi.",
        "positive": "Strain impacts on commensurate bilayer graphene superlattices: distorted\n  trigonal warping, emergence of bandgap and direct-indirect bandgap transition: Due to low dimensionality, the controlled stacking of the graphene films and\ntheir electronic properties are susceptible to environmental changes including\nstrain. The strain-induced modification of the electronic properties such as\nthe emergence and modulation of bandgaps crucially depends on the stacking of\nthe graphene films. However, to date, only the impact of strain on electronic\nproperties of Bernal and AA-stacked bilayer graphene has been extensively\ninvestigated in theoretical studies. Exploiting density functional theory and\ntight-binding calculation, we investigate the impacts of in-plane strain on two\ndifferent class of commensurate twisted bilayer graphene (TBG) which are\neven/odd under sublattice exchange (SE) parity. We find that the SE odd TBG\nremains gapless whereas the bandgap increases for the SE even TBG when applying\nequibiaxial tensile strain. Moreover, we observe that for extremely large mixed\nstrains both investigated TBG superstructures demonstrate direct-indirect\nbandgap transition."
    },
    {
        "anchor": "Statistically Modeling Optical Linewidths of Nitrogen Vacancy Centers in\n  Post-Implanted Nanostructures: We investigate the effects of a novel approach to diamond nanofabrication and\nnitrogen vacancy (NV) center formation on the optical linewidth of the NV\nzero-phonon line (ZPL). In this post-implantation method, nitrogen is implanted\nafter all fabrication processes have been completed. We examine three\npost-implanted samples, one implanted with $^{14}$N and two with $^{15}$N\nisotopes. We perform photoluminescence excitation (PLE) spectroscopy to assess\noptical linewidths and optically detected magnetic resonance (ODMR)\nmeasurements to isotopically classify the NV centers. From this, we find that\nNV centers formed from nitrogen naturally occuring in the diamond lattice are\ncharacterized by a linewidth distribution peaked at an optical linewidth nearly\ntwo orders of magnitude smaller than the distribution characterizing most of\nthe NV centers formed from implanted nitrogen. Surprisingly, we also observe a\nnumber of $^{15}$NV centers with narrow ($<500\\,\\mathrm{MHz}$) linewidths,\nimplying that implanted nitrogen can yield NV centers with narrow optical\nlinewidths. We further use a Bayesian approach to statistically model the\nlinewidth distributions, to accurately quantify the uncertainty of fit\nparameters in our model, and to predict future linewidths within a particular\nsample. Our model is designed to aid comparisons between samples and research\ngroups, in order to determine the best methods of achieving narrow NV\nlinewidths in structured samples.",
        "positive": "Field-free ultrafast magnetization reversal of a nanodevice by a chirped\n  current pulse via spin-orbit torque: We investigated the magnetization reversal of a perpendicularly magnetized\nnanodevice using a chirped current pulse (CCP) via spin-orbit torques (SOT).\nOur findings demonstrate that both the field-like (FL) and damping-like (DL)\ncomponents of SOT in CCP can efficiently induce ultrafast magnetization\nreversal without any symmetry-breaking means. For a wide frequency range of the\nCCP, the minimal current density obtained is significantly smaller compared to\nthe current density of conventional SOT-reversal. This ultrafast reversal is\ndue to the CCP triggering enhanced energy absorption (emission) of the\nmagnetization from (to) the FL- and DL-components of SOT before (after)\ncrossing over the energy barrier. We also verified the robustness of the\nCCP-driven magnetization reversal at room temperature. Moreover, this strategy\ncan be extended to switch the magnetic states of perpendicular synthetic\nantiferromagnetic (SAF) and ferrimagnetic (SFi) nanodevices. Therefore, these\nstudies enrich the basic understanding of field-free SOT-reversal and provide a\nnovel way to realize ultrafast SOT-MRAM devices with various free layer\ndesigns: ferromagnetic, SAF, and SFi."
    },
    {
        "anchor": "Optimization of the current pulse for spin-torque switches: We address optimization of the spin current intensity profile needed to\nachieve spin torque switching of a nanomagnet. For systems with Ohmic\ndissipation we prove that the optimal current drives the magnetization along\nthe trajectory, which is exact time-reversed replica of the relaxation\ntrajectory towards the equilibrium. In practice it means that the optimal\ncurrent is very nearly {\\em twice} the minimal critical current needed to\nswitch the magnet. Pulse duration of such an optimal current is a slow\nlogarithmic function of temperature and the required probability of switching.",
        "positive": "Topological transverse spin transport in a canted antiferromagnet/heavy\n  metal heterostructure: We theoretically study the conditions under which a spin Nernst effect - a\ntransverse spin current induced by an applied temperature gradient - can occur\nin a canted antiferromagnetic insulator, such as ${\\rm LaFeO_3}$ and other\nmaterials of the same family. The spin Nernst effect may provide a microscopic\nmechanism for an experimentally observed anomalous thermovoltage in ${\\rm\nLaFeO_3}$/Pt heterostructures, where spin is transferred across the\ninsulator/metal interface when a temperature gradient is applied to ${\\rm\nLaFeO_3}$ parallel to the interface [W. Lin ${\\it et \\; al}$, Nat. Phys. ${\\bf\n18}$, 800 (2022)]. We find that ${\\rm LaFeO_3}$ exhibits a topological spin\nNernst effect when inversion symmetry is broken on the axes parallel to both\nthe applied temperature gradient and the direction of spin transport, which can\nresult in a spin injection across the insulator/metal interface. Our work\nprovides a general derivation of a symmetry-breaking-induced spin Nernst\neffect, which may open a path to engineering a finite spin Nernst effect in\nsystems where it would otherwise not arise."
    },
    {
        "anchor": "McMillan-Rowell Oscillations in a Low Spin-Orbit SNS Semiconducting\n  Junction: The electronic transport properties of an SNS junction formed by an InN\nnanowire (N) and Al contacts (S) with a superconducting transition temperature\nT_c ~ 0.92 K were investigated. As a function of dc bias, superconducting\nquasiparticle transport resonance peaks at E=2\\Delta were observed, in\nagreement with BCS theory with 2\\Delta(T=0) \\equiv \\Delta_0=275\\mueV. Several\nadditional transport resonances scaling linearly in energy were observed at\nhigh-bias above 2\\Delta, up to E\\simeq 15\\Delta_0, consistent with\nMcMillan-Rowell oscillations. The persistence of McMillan-Rowell oscillations\nat high-bias and under applied magnetic field were investigated.",
        "positive": "Gd(III)-Gd(III) RIDME for In-Cell EPR Distance Determination: In-cell distance determination by EPR reveals essential structural\ninformation about biomacromolecules under native conditions. We demonstrate\nthat the pulsed EPR technique RIDME (relaxation induced dipolar modulation\nenhancement) can be utilized for such distance determination. The performance\nof in-cell RIDME has been assessed at Q band using stiff molecular rulers\nlabelled with Gd(III)-PyMTA tags and microinjected into X. laevis oocytes. The\novertone coefficients are determined to be the same for protonated aqueous\nsolutions and inside cells. As compared to in-cell DEER (double\nelectron-electron resonance, also abbreviated as PELDOR), in-cell RIDME\nfeatures approximately 5 times larger modulation depth and does not show\nartificial broadening in the distance distributions due to the effect of\npseudo-secular terms."
    },
    {
        "anchor": "Nonlinear Hall Effects in Strained Twisted Bilayer WSe$_2$: Recently, it has been pointed out that the twisting of bilayer WSe$_2$ would\ngenerate topologically non-trivial flat bands near the Fermi energy. In this\nwork, we show that twisted bilayer WSe$_2$ (tWSe$_2$) with uniaxial strain\nexhibits a large nonlinear Hall (NLH) response due to the non-trivial Berry\ncurvatures of the flat bands. Moreover, the NLH effect is greatly enhanced near\nthe topological phase transition point which can be tuned by a vertical\ndisplacement field. Importantly, the nonlinear Hall signal changes sign across\nthe topological phase transition point and provides a way to identify the\ntopological phase transition and probe the topological properties of the flat\nbands. The strong enhancement and high tunability of the NLH effect near the\ntopological phase transition point renders tWSe$_2$ and related moire materials\nnew platforms for rectification and second harmonic generations.",
        "positive": "Zero-modes and global antiferromagnetism in strained graphene: A novel magnetic ground state is reported for the Hubbard Hamiltonian in\nstrained graphene. When the chemical potential lies close to the Dirac point,\nthe ground state exhibits locally both the N\\'{e}el and ferromagnetic orders,\neven for weak Hubbard interaction. Whereas the N\\'{e}el order parameter remains\nof the same sign in the entire system, the magnetization at the boundary takes\nthe opposite sign from the bulk. The total magnetization this way vanishes, and\nthe magnetic ground state is globally only an antiferromagnet. This peculiar\nordering stems from the nature of the strain-induced single particle\nzero-energy states, which have support on one sublattice of the honeycomb\nlattice in the bulk, and on the other sublattice near the boundary of a finite\nsystem. We support our claim with the self-consistent numerical calculation of\nthe order parameters, as well as by the Monte Carlo simulations of the Hubbard\nmodel in both uniformly and non-uniformly strained honeycomb lattice. The\npresent result is contrasted with the magnetic ground state of the same Hubbard\nmodel in the presence of a true magnetic field (and for vanishing Zeeman\ncoupling), which is exclusively N\\'{e}el ordered, with zero local magnetization\neverywhere in the system."
    },
    {
        "anchor": "Extracting current-induced spins: spin boundary conditions at narrow\n  Hall contacts: We consider the possibility to extract spins that are generated by an\nelectric current in a two-dimensional electron gas with Rashba-Dresselhaus\nspin-orbit interaction (R2DEG) in the Hall geometry. To this end, we discuss\nboundary conditions for the spin accumulations between a spin-orbit coupled\nregion and contact without spin-orbit coupling, i.e. a normal two-dimensional\nelectron gas (2DEG). We demonstrate that in contrast to contacts that extend\nalong the whole sample, a spin accumulation can diffuse into the normal region\nthrough finite contacts and detected by e.g. ferromagnets. For an\nimpedance-matched narrow contact the spin accumulation in the 2DEG is equal to\nthe current induced spin accumulation in the bulk of R2DEG up to a\ngeometry-dependent numerical factor.",
        "positive": "Derivation of effective spin-orbit Hamiltonians and spin lifetimes, with\n  application to SrTiO$_3$ heterostructures: A general approach is derived for constructing an effective spin-orbit\nHamiltonian for nonmagnetic materials, which is useful for calculating\nspin-dependent properties near an arbitrary point in momentum space with\npseudospin degeneracy. The formalism is verified through comparisons with other\napproaches for III-V semiconductors, and its general applicability is\nillustrated by deriving the spin-orbit interaction and predicting spin\nlifetimes for strained SrTiO$_3$ and a two-dimensional electron gas in\nSrTiO$_3$ (such as at the LaAlO$_3$/SrTiO$_3$ interface). These results suggest\nrobust spin coherence and spin transport properties in SrTiO$_3$-based\nmaterials at room temperature."
    },
    {
        "anchor": "Quantum pumping in helimagnet heterostructures: Spin-dependent diffraction occurs in helimagnet-related transport processes.\nIn this work, we investigated quantum pumping properties in the\nnormal-metal/helimagnet/normal-metal heterostructure driven by two out of phase\ntime-dependent gate potentials. At the condition when one of the diffracted\nbeams goes out of the horizon the pumped charge and spin currents demonstrate\nsharp dips and rises as a function of the helimagnet spiral wavevector $q$. At\nsmall and large $q$'s, the transmission and pumping properties approach the\nbehaviors of a ferromagnet and an insulating barrier, respectively. For\ndifferent helimagnet spiral periods, the diffracted angles are different. As a\nresult, the pumped charge and spin currents demonstrate multiple maximal and\nminimal peaks as a function of $q$, hence, sensitively depend on the helimagnet\nspin configuration. All the pumping properties can be interpreted by the\nquantum gate-switching mechanisms.",
        "positive": "Persistent narrowing of nuclear-spin fluctuations in InAs quantum dots\n  using laser excitation: We demonstrate the suppression of nuclear spin fluctuations in an InAs\nquantum dot and measure the timescales of the spin narrowing effect. By\ninitializing for tens of milliseconds with two continuous wave diode lasers,\nfluctuations of the nuclear spins are suppressed via the hole assisted dynamic\nnuclear polarization feedback mechanism. The fluctuation narrowed state\npersists in the dark (absent light illumination) for well over one second even\nin the presence of a varying electron charge and spin polarization. Enhancement\nof the electron spin coherence time (T2*) is directly measured using coherent\ndark state spectroscopy. By separating the calming of the nuclear spins in time\nfrom the spin qubit operations, this method is much simpler than the spin echo\ncoherence recovery or dynamic decoupling schemes."
    },
    {
        "anchor": "Direct current voltage induced by microwave signal in a ferromagnetic\n  wire: Experimental results of rectification of a constant wave radio frequency (RF)\ncurrent flowing in a single-layered ferromagnetic wire are presented. We show\nthat a detailed external magnetic field dependence of the RF current induced a\ndirect-current voltage spectrum. The mechanism of the rectification is\ndiscussed in a term of the spin transfer torque, and the rectification is\nclosely related to resonant spin wave excitation with the assistant of the\nspin-polarized RF current. The micromagnetic simulation taking into account the\nspin transfer torque provides strong evidence which supports the generation of\nspin wave excitation by the RF current.",
        "positive": "Magnetic skyrmion logic gates: conversion, duplication and merging of\n  skyrmions: Magnetic skyrmions, which are topological particle-like excitations in\nferromagnets, have attracted a lot of attention recently. Skyrmionics is an\nattempt to use magnetic skyrmions as information carriers in next generation\nspintronic devices. Proposals of manipulations and operations of skyrmions are\nhighly desired. Here, we show that the conversion, duplication and merging of\nisolated skyrmions with different chirality and topology are possible all in\none system. We also demonstrate the conversion of a skyrmion into another form\nof a skyrmion, i.e., a bimeron. We design spin logic gates such as the AND and\nOR gates based on manipulations of skyrmions. These results provide important\nguidelines for utilizing the topology of nanoscale spin textures as information\ncarriers in novel magnetic sensors and spin logic devices."
    },
    {
        "anchor": "Entangled Terahertz Photon Emission from Topological Insulator Quantum\n  Dots: We propose an experimentally feasible scheme for generating entangled\nterahertz photon pairs in topological insulator quantum dots (TIQDs). We\ndemonstrate theoretically that in generic TIQDs: 1) the fine structure\nsplitting, which is the obstacle to produce entangled photons in conventional\nsemiconductor quantum dots, is inherently absent for one-dimensional massless\nexcitons due to the time-reversal symmetry; 2) the selection rules obey winding\nnumber conservation instead of the conventional angular momentum conservation\nbetween edge states with a linear dispersion. With these two advantages, the\nentanglement of the emitted photons during the cascade in our scheme is robust\nagainst unavoidable disorders and irregular shapes of the TIQDs.",
        "positive": "All-electrical time-resolved spin generation and spin manipulation in\n  n-InGaAs: We demonstrate all-electrical spin generation and subsequent manipulation by\ntwo successive electric field pulses in an n-InGaAs heterostructure in a\ntime-resolved experiment at zero external magnetic field. The first electric\nfield pulse along the $[1\\bar10]$ crystal axis creates a current induced spin\npolarization (CISP) which is oriented in the plane of the sample. The\nsubsequent electric field pulse along [110] generates a perpendicular magnetic\nfield pulse leading to a coherent precession of this spin polarization with\n2-dimensional electrical control over the final spin orientation. Spin\nprecession is probed by time-resolved Faraday rotation. We determine the\nbuild-up time of CISP during the first field pulse and extract the spin\ndephasing time and internal magnetic field strength during the spin\nmanipulation pulse."
    },
    {
        "anchor": "Ultra-high quality two-dimensional electron systems: Two-dimensional electrons confined to GaAs quantum wells are hallmark\nplatforms for probing electron-electron interaction. Many key observations have\nbeen made in these systems as sample quality improved over the years. Here, we\npresent a breakthrough in sample quality via source-material purification and\ninnovation in GaAs molecular beam epitaxy vacuum chamber design. Our samples\ndisplay an ultra-high mobility of $44\\times10^6$ cm$^2$/Vs at an electron\ndensity of $2.0\\times10^{11}$ /cm$^2$. These results imply only 1 residual\nimpurity for every $10^{10}$ Ga/As atoms. The impact of such low impurity\nconcentration is manifold. Robust stripe/bubble phases are observed, and\nseveral new fractional quantum Hall states emerge. Furthermore, the activation\ngap of the $\\nu=5/2$ state, which is widely believed to be non-Abelian and of\npotential use for topological quantum computing, reaches $\\Delta\\simeq820$ mK.\nWe expect that our results will stimulate further research on\ninteraction-driven physics in a two-dimensional setting and significantly\nadvance the field.",
        "positive": "Spin echo dynamics under an applied drift field in graphene nanoribbon\n  superlattices: We investigate the evolution of spin dynamics in graphene nanoribbon\nsuperlattices (GNSLs) with armchair and zigzag edges in the presence of a drift\nfield. We determine the exact evolution operator and show that it exhibits spin\necho phenomena due to rapid oscillations of the quantum states along the\nribbon. The evolution of the spin polarization is accompanied by strong beating\npatterns. We also provide detailed analysis of the band structure of GNSLs with\narmchair and zigzag edges."
    },
    {
        "anchor": "Atom-molecule coexistence and collective dynamics near a Feshbach\n  resonance of cold fermions: Degenerate Fermi gas interacting with molecules near Feshbach resonance is\nunstable with respect to formation of a mixed state in which atoms and\nmolecules coexist as a coherent superposition. Theory of this state is\ndeveloped using a mapping to the Dicke model, treating molecular field in the\nsingle mode approximation. The results are accurate in the strong coupling\nregime relevant for current experimental efforts. The exact solution of the\nDicke model is exploited to study stability, phase diagram, and nonadiabatic\ndynamics of molecular field in the mixed state.",
        "positive": "Molecular junctions and molecular motors: Including Coulomb repulsion in\n  electronic friction using nonequilibrium Green's functions: We present a theory of molecular motors based on the Ehrenfest dynamics for\nthe nuclear coordinates and the adiabatic limit of the Kadanoff-Baym equations\nfor the current-induced forces. Electron-electron interactions can be\nsystematically included through many-body perturbation theory, making the\nnonequilibrium Green's functions formulation suitable for first-principles\ntreatments of realistic junctions. The method is benchmarked against\nsimulations via real-time Kadanoff-Baym equations, finding an excellent\nagreement. Results on a paradigmatic model of molecular motor show that\ncorrelations can change dramatically the physical scenario by, e.g. introducing\na sizable damping in the self-sustained van der Pol oscillations."
    },
    {
        "anchor": "A Topological SQUIPT based on helical edge states in proximity to\n  superconductors: We propose a device based on a topological Josephson junction where the\nhelical edge states of a two-dimensional topological insulator are in close\nproximity to two superconducting leads. The presence of a magnetic flux through\nthe junction leads to a Doppler shift in the spectrum of Andreev bound states,\nand affects the quantum interference between proximized edge states. We inspect\nthe emergent features, accessing the density of states through a tunnel-coupled\nmetallic probe, thus realizing a Topological Superconducting Quantum\nInterference Proximity Transistor (TSQUIPT). We calculate the expected\nperformances of this new device, concluding that it can be used as a sensitive,\nabsolute magnetometer due to the voltage drop across the junction decaying to a\nconstant value as a function of the magnetic flux. Contrary to conventional\nSQUID and SQUIPT designs, no ring structure is needed. The findings pave the\nway for novel and sensitive devices based on hybrid devices that exploit\nhelical edge states.",
        "positive": "Reversible Actuation of $\u03b1$-Borophene Nanoscrolls: In this work, we proposed and investigated the structural and electronic\nproperties of boron-based nanoscrolls (armchair and zigzag) using the DFTB+\nmethod. We also investigated the electroactuation process (injecting and\nremoving charges). A giant electroactuation was observed, but the results show\nrelevant differences between the borophene and carbon nanoscrolls. The\nmolecular dynamics simulations showed that the scrolls are thermally and\nstructurally stable for a large range of temperatures (up to 600K) and the\nelectroactuation process can be easily tuned and can be entirely reversible for\nsome configurations."
    },
    {
        "anchor": "Evolution of domain structure with electron doping in ferroelectric thin\n  films: To minimize their electrostatic energy, insulating ferroelectric films tend\nto break up into nanoscale ``Kittel'' domains of opposite polarization that are\nseparated by uncharged 180$^\\circ$ domain walls. Here, I report on\nself-consistent solutions of coupled Landau-Ginzburg-Devonshire and\nSchr\\\"odinger equations for an electron-doped ferroelectric thin film. The\nmodel is based on LaAlO$_3$/SrTiO$_3$ interfaces in which the SrTiO$_3$\nsubstrate is made ferroelectric by cation substitution or strain. I find that\nelectron doping destabilizes the Kittel domains. As the two-dimensional\nelectron density $n_\\mathrm{2D}$ increases, there is a smooth crossover to a\nzigzag domain wall configuration. The domain wall is positively charged, but is\ncompensated by the electron gas, which attaches itself to the domain wall and\nscreens depolarizing fields. The domain wall approaches a flat head-to-head\nconfiguration in the limit of perfect screening. The polarization profile may\nbe manipulated by an external bias voltage and the electron gas may be switched\nbetween surfaces of the ferroelectric film.",
        "positive": "Grain boundary network plasticity: reduced-order modeling of\n  deformation-driven microstructure evolution: Microstructural evolution in structural materials is known to occur in\nresponse to mechanical loading and can often accommodate substantial plastic\ndeformation through the coupled motion of grain boundaries (GBs). This can\nproduce desirable behavior, such as increased ductility, or undesirable\nbehavior such as mechanically-induced coarsening. In this work a novel,\nmultiscale model is developed for capturing the combined effect of plasticity\nmediated by multiple GBs simultaneously. This model is referred to as \"grain\nboundary network plasticity.\" The mathematical framework of graph theory is\nused to describe the microstructure connectedness, and the evolution of\nmicrostructure is represented as volume flow along the graph. By using the\nprinciple of minimum dissipation potential, which has previously been applied\nto grain boundary migration, a set of evolution equations are developed that\ntransfer volume and eigendeformation along the graph edges in a physically\nconsistent way. It is shown that higher-order geometric effects, such as the\npinning effect of triple points, may be accounted for through the incorporation\nof a geometric hardening that causes geometry-induced GB stagnation. The result\nis a computationally efficient reduced order model that can be used to simulate\nthe initial motion of grain boundaries in a polycrystal with parameters\ninformed by atomistic simulations. The effectiveness of the model is\ndemonstrated through comparison to multiple bicrystal atomistic simulations, as\nwell as a select number of GB engineered and non-GB engineered data obtained\nfrom the literature. The effect of the network of shear-coupling grain\nboundaries is demonstrated through mechanical response tests and by examining\nthe yield surfaces."
    },
    {
        "anchor": "How light absorption modifies the radiative force on a microparticle in\n  optical tweezers: Reflection and refraction of light can be used to trap small dielectric\nparticles in the geometrical optics regime. Absorption of light is usually\nneglected in theoretical calculations, but it is known that it occurs in the\noptical trapping of metallic particles. Also, recent experiments with\nsemi-transparent microparticles have shown that absorption of light is\nimportant to explain their optically induced oscillations. Here, we propose a\ngeneralization of Ashkin's model for the radiative force exerted on a spherical\nbead, including the contribution due to attenuation/absorption of light in the\nbulk of the particle. We discuss in detail the balance between refraction,\nreflection and absorption for different optical parameters and particle sizes.\nA detailed example is provided in order to clarify how the model can be\napplied, and it is obtained that the radiative force can either increase or\ndecrease with absorption, depending on the particle size. Our findings\ncontribute to the understanding of optical trapping of light-absorbing\nparticles, and may be used to predict whenever absorption is important in real\nexperiments.",
        "positive": "Noise dephasing in the edge states of the Integer Quantum Hall regime: An electronic Mach Zehnder interferometer is used in the integer quantum hall\nregime at filling factor 2, to study the dephasing of the interferences. This\nis found to be induced by the electrical noise existing in the edge states\ncapacitively coupled to each others. Electrical shot noise created in one\nchannel leads to phase randomization in the other, which destroys the\ninterference pattern. These findings are extended to the dephasing induced by\nthermal noise instead of shot noise: it explains the underlying mechanism\nresponsible for the finite temperature coherence time $\\tau_\\phi(T)$ of the\nedge states at filling factor 2, measured in a recent experiment. Finally, we\npresent here a theory of the dephasing based on Gaussian noise, which is found\nin excellent agreement with our experimental results."
    },
    {
        "anchor": "Weyl superconductors: We study the physics of the superconducting variant of Weyl semimetals, which\nmay be realized in multilayer structures comprising topological insulators and\nsuperconductors. We show how superconductivity can split each Weyl node into\ntwo. The resulting Bogoliubov Weyl nodes can be pairwise independently\ncontrolled, allowing to access a set of phases characterized by different\nnumbers of bulk Bogoliubov Weyl nodes and chiral Majorana surface modes. We\nanalyze the physics of vortices in such systems, which trap zero energy\nMajorana modes only under certain conditions. We finally comment on possible\nexperimental probes, thereby also exploiting the similarities between Weyl\nsuperconductors and 2-dimensional p + ip superconductors.",
        "positive": "Controllable Spin-Transfer Torque on an Antiferromagnet in a Dual\n  Spin-Valve: We consider current-induced spin-transfer torque on an antiferromagnet in a\ndual spin-valve setup. It is demonstrated that a net magnetization may be\ninduced in the AFM by partially or completely aligning the sublattice\nmagnetizations via a current-induced spin-transfer torque. This effect occurs\nfor current densities ranging below 10$^6$ A/cm$^2$. The direction of the\ninduced magnetization in the AFM is shown to be efficiently controlled by means\nof the magnetic configuration of the spin-valve setup, with the anti-parallell\nconfiguration yielding the largest spin-transfer torque. Interestingly, the\nmagnetization switching time-scale $\\tau_\\text{switch}$ itself has a strong,\nnon-monotonic dependence on the spin-valve configuration. These results may\npoint toward new ways to incorporate AFMs in spintronic devices in order to\nobtain novel types of functionality."
    },
    {
        "anchor": "Current-induced spin polarization for a general two-dimensional electron\n  system: In this paper, current-induced spin polarization for two-dimensional electron\ngas with a general spin-orbit interaction is investigated. For isotropic energy\nspectrum, the in-plane current-induced spin polarization is found to be\ndependent on the electron density for non-linear spin-orbit interaction and\nincreases with the increment of sheet density, in contrast to the case for $\\bm\nk$-linear spin-orbit coupling model. The numerical evaluation is performed for\nInAs/InSb heterojunction with spin-orbit coupling of both linear and cubic\nspin-orbit coupling types. For $\\delta$-type short-range electron-impurity\nscattering, it is found that the current-induced spin polarization increases\nwith increasing the density when cubic spin-orbit couplings are considered.\nHowever, for remote disorders, a rapid enhancement of current-induced spin\npolarization is always observed at high electron density, even in the case\nwithout cubic spin-orbit coupling. This result demonstrates the\ncollision-related feature of current-induced spin polarization. The effects of\ndifferent high order spin-orbit couplings on spin polarization can be\ncomparable.",
        "positive": "Spin relaxation: From 2D to 1D: In inversion asymmetric semiconductors, spin-orbit interactions give rise to\nvery effective relaxation mechanisms of the electron spin. Recent work, based\non the dimensionally constrained D'yakonov Perel' mechanism, describes\nincreasing electron-spin relaxation times for two-dimensional conducting layers\nwith decreasing channel width. The slow-down of the spin relaxation can be\nunderstood as a precursor of the one-dimensional limit."
    },
    {
        "anchor": "Charge sensing amplification via weak values measurement: A protocol employing weak values (WVs) to obtain ultra sensitive\namplification of weak signals in the context of a solid state setup is\nproposed. We consider an Aharonov-Bohm interferometer where both the orbital\nand the spin degrees of freedom are weakly affected by the presence of an\nexternal charge to be detected. The interplay between the spin and the orbital\nWVs leads to a significant amplification even in the presence of finite\ntemperature, voltage, and external noise.",
        "positive": "Optical orientation of hole magnetic polarons in (Cd,Mn)Te/(Cd,Mn,Mg)Te\n  quantum wells: The optically induced spin polarization in (Cd,Mn)Te/(Cd,Mn,Mg)Te\ndiluted-magnetic-semiconductor quantum wells is investigated by means of\npicosecond pump-probe Kerr rotation. At 1.8 K temperature, additionally to the\noscillatory signals from photoexcited electrons and Manganese spins precessing\nabout an external magnetic field, a surprisingly long-lived (up to 60 ns)\nnonoscillating spin polarization is detected. This polarization is related to\noptical orientation of equilibrium magnetic polarons involving resident holes.\nThe suggested mechanism for the optical orientation of the equilibrium magnetic\npolarons indicates that the detected polaron dynamics originates from unexcited\nmagnetic polarons. The polaron spin dynamics is controlled by the anisotropic\nspin structure of the heavy-hole resulting in a freezing of the polaron\nmagnetic moment in one of the two stable states oriented along the structure\ngrowth axis. Spin relaxation between these states is prohibited by a potential\nbarrier, which depends on temperature and magnetic field. The magnetic polaron\nrelaxation is accelerated with increasing temperature and in magnetic field."
    },
    {
        "anchor": "Point contacts and localization in generic helical liquids: We consider two helical liquids on opposite edges of a narrow two-dimensional\ntopological insulator, which are connected by one or several local tunnel\njunctions. In the presence of spatially inhomogeneous Rashba spin-orbit\ncoupling, the spin textures of the helical states on opposite edges are\ndifferent. We demonstrate that this has a strong impact on the electron\ntransport between the edges. In particular, in the case of many random tunnel\ncontacts, the localization length depends strongly on the spin textures of the\nedge states.",
        "positive": "Electronic and spin transport in Bismuthene with magnetic impurities: Topological insulators have remained as candidates for future electronic\ndevices since their first experimental realization in the past decade. The\nexistence of topologically protected edge states could be exploited to generate\na robust platform and develop quantum computers. In this work we explore the\nrole of magnetic impurities in the transport properties of topological\ninsulators, in particular, we study the effect on the edge states conductivity.\nBy means of realistic $\\it{ab}$ $\\it{initio}$ calculations we simulate the\ninteraction between magnetic adatoms and topological insulators, furthermore,\nour main goal is to obtain the transport properties for large samples as it\nwould be possible to localize edge states at large scales."
    },
    {
        "anchor": "Floquet scattering matrix theory of heat fluctuations in dynamical\n  quantum conductors: I present the Floquet scattering matrix theory of low-frequency heat\nfluctuations in driven multi-terminal quantum-coherent conductors in the linear\nresponse regime and beyond. The intrinsic fluctuations of energy of dynamically\nexcited electrons are identified as the fundamental source of a heat noise not\nrevealed by the electrical noise. The role of backscattering in the increase of\na heat noise above the level defined by the Callen-Welton\nfluctuation-dissipation theorem, is highlighted.",
        "positive": "Quantitative nanoscale MRI with a wide field of view: Magnetic spin resonance is a key non-invasive sensing and imaging technique\nacross the life-, material- and fundamental sciences with further medical and\ncommercial applications. Recent advances using paramagnetic color centers\nenable magnetic resonance down on the nanoscale, and sensitivity to single\nmolecules is in sight. Ensemble sensing and wide field imaging improve\nsensitivity and acquisition speed, but may suffer from inhomogeneous spin\ncontrol fields, produced by e.g. microstructures in integrated devices, and\nlimited spatial resolution. Here we demonstrate multiplexed nuclear magnetic\nresonance imaging using diamond nitrogen-vacancy centers in such adverse\nconditions. We image thin films of calcium fluoride down to $1.2\\,\\mathrm{nm}$\nin thickness with a spatial resolution of $250\\,\\mathrm{nm}$. This corresponds\nto a net moment of about 140 nuclear spins within the sensing radius of a given\nNV in the ensemble."
    },
    {
        "anchor": "Phonon-induced giant linear-in-$T$ resistivity in magic angle twisted\n  bilayer graphene: Ordinary strangeness and exotic superconductivity: We study the effect of electron-acoustic phonon interactions in twisted\nbilayer graphene on resistivity in the high-temperature transport and\nsuperconductivity in the low-temperature phase diagram. We theoretically show\nthat twisted bilayer graphene should have an enhanced and strongly twist-angle\ndependent linear-in-temperature resistivity in the metallic regime with the\nresistivity magnitude increasing as the twist angle approaches the magic angle.\nThe slope of the resistivity versus temperature could approach one hundred ohms\nper kelvin with a strong angle dependence, but with a rather weak dependence on\nthe carrier density. This higher-temperature density-independent linear-in-$T$\nresistivity crosses over to a $T^4$ dependence at a low density-dependent\ncharacteristic temperature, becoming unimportant at low temperatures. This\nangle-tuned resistivity enhancement arises from the huge increase in the\neffective electron-acoustic phonon coupling in the system due to the\nsuppression of graphene Fermi velocity induced by the flatband condition in the\nmoir\\'e superlattice system. Our calculated temperature dependence is\nreminiscent of the so-called `strange metal' transport behavior except that it\nis arising from the ordinary electron-phonon coupling in a rather unusual\nparameter space due to the generic moir\\'e flatband structure of twisted\nbilayer graphene. We also show that the same enhanced electron-acoustic phonon\ncoupling also mediates effective attractive interactions in $s$, $p$, $d$ and\n$f$ pairing channels with a theoretical superconducting transition temperature\non the order of $\\sim$5 K near magic angle. The fact that ordinary acoustic\nphonons can produce exotic non-$s$-wave superconducting pairing arises from the\nunusual symmetries of the system.",
        "positive": "Spin pumping by a field-driven domain wall: We calculate the charge current in a metallic ferromagnet to first order in\nthe time derivative of the magnetization direction. Irrespective of the\nmicroscopic details, the result can be expressed in terms of the conductivities\nof the majority and minority electrons and the non-adiabatic spin transfer\ntorque parameter $\\beta$. The general expression is evaluated for the specific\ncase of a field-driven domain wall and for that case depends strongly on the\nratio of $\\beta$ and the Gilbert damping constant. These results may provide an\nexperimental method to determine this ratio, which plays a crucial role for\ncurrent-driven domain-wall motion."
    },
    {
        "anchor": "Non-factorizable 4D quantum Hall state from photonic crystal defects: In the recent years, there has been a drive towards the realization of\ntopological phases beyond conventional electronic materials, including phases\ndefined in more than three dimensions. We propose a way to realize 2nd Chern\nnumber topological phases with photonic crystals simply made up of defect\nresonators embedded within a regular lattice of resonators. In particular,\nthrough a novel quasiperiodic spatial modulations in the defect radii, a defect\nlattice possessing topologically nontrivial Chern bands with non-abelian berry\ncurvature living in four-dimensional synthetic space is proposed. This system\ncannot be factorized by a direct product of two 1st Chern number models,\ndistinguishing itself from the Hofstadter model. Such photonic systems can be\neasily experimentally realized with regular photonic crystals consisting of\ndielectric rods in air.",
        "positive": "Heterointerface potentials in the effective-mass approximation for\n  wurtzite semiconductor structures: In the effective-mass approximation, the step-like crystal potential of a\nwurtzite semiconductor heterostucture should be supplemented by Dirac\ndelta-function heterointerface terms. They stem from the difference in the\nBloch functions of the semiconductors and remain finite even for structures\nwith graded chemical composition, where the terms are presented by a smeared\nDirac delta function. We find these heterointerface potentials by employing the\nk*p method, and evaluate their strength from band-structure parameters of bulk\nmaterials. These potentials are weak for semiconductors compliant with the\ncubic approximation, which forces the zinc-blende crystal symmetry upon the\nwurtzite lattice. Nevertheless, they can produce a noteworthy effect due to a\nstrong built-in electric field usually present in wurtzite heterostructures. We\nestimate that for GaN/AlN [0001] heterojunctions their net contributions to the\nenergy of conduction and valence band states are 3 meV and 10 meV,\nrespectively. The presence of the interface potential can modify the shape of\nthe valence-band spectrum calculated without the potential."
    },
    {
        "anchor": "The optimum configuration design of a nanostructured thermoelectric\n  device with resonance tunneling: A nanostructured thermoelectric device is designed by connecting a\ndouble-barrier resonant tunneling heterostructure to two electron reservoirs.\nBased on Landauers equation and Fermi-Dirac statistics, the exact solution of\nthe heat flow is calculated. The maximum power output and efficiency are\ncalculated through the optimizations of several key parameters. The optimum\ncharacteristic curve of the performance is obtained. The reasonably working\nregion of the device is determined, the selection criteria of main parameters\nare provided, and the optimum configuration of the device is drawn. Results\nshow that the heterojunction becomes a perfect energy filter by appropriately\nregulating the chemical potentials of electron reservoirs and optimally\nchoosing the widths of barrier and quantum well and the nanostructured\nthermoelectric device with resonance tunneling may obtain simultaneously a\nlarge power output and a high efficiency.",
        "positive": "Topological parafermion corner states in clock-symmetric non-Hermitian\n  second-order topological insulator: Parafermions are a natural generalization of Majorana fermions. We consider a\nbreathing Kagome lattice with complex hoppings by imposing $\\mathbb{Z}_{3}$\nclock symmetry in the complex energy plane. It is a non-Hermitian\ngeneralization of the second-order topological insulator characterized by the\nemergence of topological corner states. We demonstrate that the topological\ncorner states are parafermions in the present $\\mathbb{Z}_{3}$ clock-symmetric\nmodel. It is also shown that the model is realized in electric circuits\nproperly designed, where the parafermion corner states are observed by\nimpedance resonance. We also construct $\\mathbb{Z}_{4}$ and $\\mathbb{Z}_{6}$\nparafermions on breathing square and honeycomb lattices, respectively."
    },
    {
        "anchor": "Plasmonic Purcell Effect in Organic Molecules: By means of quantum tensor network calculations, we investigate the large\nPurcell effect experienced by an organic molecule placed in the vicinity of a\nplasmonic nanostructure. In particular, we consider a donor-{\\pi}\nbridge-acceptor dye at the gap of two Ag nanospheres. Our theoretical approach\nallows for a realistic description of the continua of both molecular vibrations\nand optical nanocavity modes. We analyze both the exciton dynamics and the\ncorresponding emission spectrum, showing that these magnitudes are not\naccurately represented by the simplified models used up to date. By\ndisentangling the molecule coupling to radiative and non-radiative plasmonic\nmodes, we also shed light into the quenching phenomenology taking place in the\nsystem.",
        "positive": "Robustness of equilibrium off-diagonal current fluctuation against\n  localization of electron states in macroscopic two-dimensional systems: We study the off-diagonal current fluctuation in a macroscopic quantum system\nmeasured in an ideal manner that is as close as possible to the classical ideal\nmeasurement. We show rigorously that not only extended but also localized\nstates contribute to the off-diagonal current fluctuation. This result\ncontrasts with the fact that only the extended states affect the off-diagonal\n(Hall) conductivity and apparently contradicts the naive expectation from the\nfluctuation-dissipation theorem that might directly connect these two\nquantities. More specifically, we study the off-diagonal current fluctuation in\na disordered two-dimensional electron system in a strong magnetic field at low\ntemperatures. The fluctuation is almost unchanged from that of the pure system\nreflecting the property mentioned above, being approximately proportional to\nthe Landau level filling factor with high accuracy. Our finding paves the way\nto estimate the filling factor and the electron density from the off-diagonal\ncurrent fluctuation observed in macroscopic systems."
    },
    {
        "anchor": "Single-molecule conductance of a chemically modified, \u03c0-extended\n  tetrathiafulvalene and its charge-transfer complex with F4TCNQ: We describe the synthesis and single molecule electrical transport properties\nof a molecular wire containing a ${\\pi}$-extended tetrathiafulvalene (exTTF)\ngroup and its charge-transfer complex with F4TCNQ. We form single molecule\njunctions using the in-situ break junction technique using a home-built\nscanning tunneling microscope with a range of conductance between 10 G$_{0}$\ndown to 10$^{-7}$ G$_{0}$. Within this range we do not observe a clear\nconductance signature of the neutral parent molecule, suggesting either that\nits conductance is too low or that it does not form stable junctions.\nConversely, we do find a clear conductance signature in the experiments carried\nout on the charge-transfer complex. Due to the fact we expected this species to\nhave a higher conductance than the neutral molecule, we believe this supports\nthe idea that the conductance of the neutral molecule is very low, below our\nmeasurement sensitivity. This is further supported by our theoretical\ncalculations. To the best of our knowledge, these are the first reported single\nmolecule conductance measurements on a molecular charge-transfer species.",
        "positive": "Magnetoresistance when Spin Effects on Conduction are Weak: This paper considers certain materials, including topological insulators,\nwhere spin rotation symmetry is broken much more strongly than time reversal\nsymmetry. When these materials are in the diffusive regime, i.e. when they have\ndisorder that is strong enough to cause an electron to scatter many times while\ncrossing a sample, electrons and holes move in pairs that have zero spin and\nare insensitive to spin physics. Working within this spinless scenario, we show\nthat Fourier transforming the magnetoconductance with respect to external\nmagnetic field obtains a curve describing the area distribution of loops traced\nby electrons and holes within the sample. We present loop area distributions of\nLandau levels, weak (anti)localization, conduction governed by Levy flights,\nand linear-in-field resistance. Of these four the last two are new results.\nComparing these distributions, we argue that the linear-in-field resistance\nseen in some topological insulators is caused by the same diffusive scattering\nthat causes weak antilocalization. The difference is that linear-in-field\nresistance materials retain a level of quantum coherence that is usually seen\nonly on the surface of 2-D wires or in ring geometries. In an appendix we\ninclude some speculative material about linear-in-temperature resistance."
    },
    {
        "anchor": "Nonchiral Edge States at the Chiral Metal Insulator Transition in\n  Disordered Quantum Hall Wires: The quantum phase diagram of disordered wires in a strong magnetic field is\nstudied as a function of wire width and energy. The two-terminal conductance\nshows zero-temperature discontinuous transitions between exactly integer\nplateau values and zero. In the vicinity of this transition, the chiral\nmetal-insulator transition (CMIT), states are identified that are\nsuperpositions of edge states with opposite chirality. The bulk contribution of\nsuch states is found to decrease with increasing wire width. Based on exact\ndiagonalization results for the eigenstates and their participation ratios, we\nconclude that these states are characteristic for the CMIT, have the appearance\nof nonchiral edges states, and are thereby distinguishable from other states in\nthe quantum Hall wire, namely, extended edge states, two-dimensionally (2D)\nlocalized, quasi-1D localized, and 2D critical states.",
        "positive": "Magnetic power inverter: AC voltage generation from DC magnetic fields: We propose a method that allows power conversion from DC magnetic fields to\nAC electric voltages using domain wall (DW) motion in ferromagnetic nanowires.\nThe device concept relies on spinmotive force, voltage generation due to\nmagnetization dynamics. Sinusoidal modulation of the nanowire width introduces\na periodic potential for a DW the gradient of which exerts variable pressure on\nthe traveling DW. This results in time variation of the DW precession frequency\nand the associated voltage. Using a one-dimensional model we show that the\nfrequency and amplitude of the AC outputs can be tuned by the DC magnetic\nfields and wire-design."
    },
    {
        "anchor": "From classical to quantum spintronics: Theory of coherent spin injection\n  and spin valve phenomena: We present a theory of coherent quantum transport in ferromagnetic/\nnon-magnetic/ ferromagnetic heterojunctions. We predict quantum coherence to\ngive rise to a quantum spin valve effect that, unlike its familiar classical\nanalog, occurs even in the absence of a net spin current through the\nheterostructure. Thus the relationship between spin and charge transport is\nqualitatively different in the presence of quantum interference than in the\n(semi)classical regime. This has important implications for the design of\nquantum coherent spintronic devices and the interpretation of experiments.",
        "positive": "Ultrafast reorientation of the N\u00e9el vector in antiferromagnetic Dirac\n  semimetals: Antiferromagnets exhibit distinctive characteristics such as ultrafast\ndynamics and robustness against perturbative fields, thereby attracting\nconsiderable interest in fundamental physics and technological applications.\nRecently, it was revealed that the N\\'eel vector can be switched by a\ncurrent-induced staggered (N\\'eel) spin-orbit torque in antiferromagnets with\nthe parity-time symmetry, and furthermore, a nonsymmorphic symmetry enables the\ncontrol of Dirac fermions. However, the real-time dynamics of the magnetic and\nelectronic structures remain largely unexplored. Here, we propose a theory of\nthe ultrafast dynamics in antiferromagnetic Dirac semimetals and show that the\nN\\'eel vector is rotated in the picosecond timescale by the\nterahertz-pulse-induced N\\'eel spin-orbit torque and other torques originating\nfrom magnetic anisotropies. This reorientation accompanies the modulation of\nthe mass of Dirac fermions and can be observed in real time by the\nmagneto-optical effects. Our results provide a theoretical basis for emerging\nultrafast antiferromagnetic spintronics combined with the topological aspects\nof materials."
    },
    {
        "anchor": "Does the side jump effect exist?: The side-jump effect is a manifestation of the spin orbit interaction in\nelectron scattering from an atom/ion/impurity. The effect has a broad interest\nbecause of its conceptual importance for generic spin-orbital physics, in\nparticular the effect is widely discussed in spintronics. We reexamine the\neffect accounting for the exact nonperturbative electron wave function inside\nthe atomic core. We find that value of the effect is much smaller than\nestimates accepted in literature. The reduction factor is 1/Z^2, where Z is the\nnucleus charge of the atom/impurity. This implies that the side-jump effect is\npractically irrelevant for spintronics, the skew scattering and/or the\nintrinsic mechanism always dominate the anomalous Hall and spin Hall effects.",
        "positive": "Stability of Suspended Graphene under Casimir Force: We consider graphene sheet suspended above a conducting surface. Treating\ngraphene as an elastic membrane subjected to Casimir force, we study its\nstability against attachment to the conductor. There exists a critical\nelevation at the edges below which the central part of suspended graphene\nnucleates a trunk that becomes attached to the conductor. The dependence of the\ncritical elevation on temperature and dimensions of the graphene sheet is\ncomputed."
    },
    {
        "anchor": "Engineering interfacial quantum states and electronic landscapes by\n  molecular nanoarchitectures: Surfaces are at the frontier of every known solid. They provide versatile\nsupports for functional nanostructures and mediate essential physicochemical\nprocesses. Being intimately related with 2D materials, interfaces and\natomically thin films often feature distinct electronic states with respect to\nthe bulk, which are key for many relevant properties, such as catalytic\nactivity, interfacial charge-transfer, or crystal growth mechanisms. Of\nparticular interest is reducing the surface electrons' dimensionality and\nspread with atomic precision, to induce novel quantum properties via lateral\nscattering and confinement. Both atomic manipulation and supramolecular\nprinciples provide access to custom-designed molecular superlattices, which\ntailor the surface electronic landscape and influence fundamental chemical and\nphysical properties at the nanoscale. Herein, we review the confinement of\nsurface state electrons focusing on their interaction with molecule-based\nscaffolds created by molecular manipulation and self-assembly protocols under\nultrahigh vacuum conditions. Starting from the quasi-free 2D electron gas\npresent at the (111)-terminated surface planes of noble metals, we illustrate\nthe enhanced molecule-based structural complexity and versatility compared to\nsimple atoms. We survey low-dimensional confining structures in the form of\nartificial lattices, molecular nanogratings or quantum dot arrays, which are\nconstructed upon appropriate choice of their building constituents. Whenever\nthe realized (metal-)organic networks exhibit long-range order, modified\nsurface band structures with characteristic features emerge, revealing\nintriguing physical properties, such as discretization, quantum coupling or\nenergy and effective mass renormalization. Such collective electronic states\ncan be additionally modified by positioning guest species at the voids of open\nnanoarchitectures [...].",
        "positive": "A General Theorem Relating the Bulk Topological Number to Edge States in\n  Two-dimensional Insulators: We prove a general theorem on the relation between the bulk topological\nquantum number and the edge states in two dimensional insulators. It is shown\nthat whenever there is a topological order in bulk, characterized by a\nnon-vanishing Chern number, even if it is defined for a non-conserved quantity\nsuch as spin in the case of the spin Hall effect, one can always infer the\nexistence of gapless edge states under certain twisted boundary conditions that\nallow tunneling between edges. This relation is robust against disorder and\ninteractions, and it provides a unified topological classification of both the\nquantum (charge) Hall effect and the quantum spin Hall effect. In addition, it\nreconciles the apparent conflict between the stability of bulk topological\norder and the instability of gapless edge states in systems with open\nboundaries (as known happening in the spin Hall case). The consequences of time\nreversal invariance for bulk topological order and edge state dynamics are\nfurther studied in the present framework."
    },
    {
        "anchor": "Charge transport through weakly open one dimensional quantum wires: We consider resonant transmission through a finite-length quantum wire\nconnected to leads via finite transparency junctions. The coherent electron\ntransport is strongly modified by the Coulomb interaction. The low-temperature\ncurrent-voltage ($IV$) curves show step-like dependence on the bias voltage\ndetermined by the distance between the quantum levels inside the conductor, the\npattern being dependent on the ratio between the charging energy and level\nspacing. If the system is tuned close to the resonance condition by the gate\nvoltage, the low-voltage $IV$ curve is Ohmic. At large Coulomb energy and low\ntemperatures, the conductance is temperature-independent for any relationship\nbetween temperature, level spacing, and coupling between the wire and the\nleads.",
        "positive": "Self-consistent local-equilibrium model for density profile and\n  distribution of dissipative currents in a Hall bar under strong magnetic\n  fields: Recent spatially resolved measurements of the electrostatic-potential\nvariation across a Hall bar in strong magnetic fields, which revealed a clear\ncorrelation between current-carrying strips and incompressible strips expected\nnear the edges of the Hall bar, cannot be understood on the basis of existing\nequilibrium theories. To explain these experiments, we generalize the\nThomas-Fermi--Poisson approach for the self-consistent calculation of\nelectrostatic potential and electron density in {\\em total} thermal equilibrium\nto a {\\em local equilibrium} theory that allows to treat finite gradients of\nthe electrochemical potential as driving forces of currents in the presence of\ndissipation. A conventional conductivity model with small values of the\nlongitudinal conductivity for integer values of the (local) Landau-level\nfilling factor shows that, in apparent agreement with experiment, the current\ndensity is localized near incompressible strips, whose location and width in\nturn depend on the applied current."
    },
    {
        "anchor": "Pseudospin Transfer Torques in Semiconductor Electron Bilayers: We use self-consistent quantum transport theory to investigate the influence\nof electron-electron interactions on interlayer transport in semiconductor\nelectron bilayers in the absence of an external magnetic field. We conclude\nthat, even though spontaneous pseudospin order does not occur at zero field,\ninteraction-enhanced quasiparticle tunneling amplitudes and pseudospin transfer\ntorques do alter tunneling I-V characteristics, and can lead to time-dependent\nresponse to a dc bias voltage.",
        "positive": "Current-induced atomic motion, structural instabilities, and negative\n  temperatures on molecule-electrode interfaces in electronic junctions: Molecule-electrode interfaces in molecular electronic junctions are prone to\nchemical reactions, structural changes, and localized heating effects caused by\nelectric current. These can be exploited for device functionality or may be\ndegrading processes that limit performance and device lifetime. We develop a\nnonequilibrium Green's function based transport theory in which the central\nregion atoms and, more importantly, atoms on molecule-electrode interfaces are\nallowed to move. The separation of time-scales of slow nuclear motion and fast\nelectronic dynamics enables the algebraic solution of the Kadanoff-Baym\nequations in the Wigner space. As a result, analytical expressions for\ndynamical corrections to the adiabatically computed Green's functions are\nproduced. These dynamical corrections depend not only on the instantaneous\nmolecular geometry but also on the nuclear velocities. To make the theoretical\napproach fully self-consistent, the same time-separation approach is used to\ndevelop expressions for the adiabatic, dissipative, and stochastic components\nof current-induced forces in terms of adiabatic Green's functions. Using these\ncurrent induced forces, the equation of motion for the nuclear degrees of\nfreedom is cast in the form of a Langevin equation. The theory is applied to\nmodel molecular electronic junctions. We observe that the interplay between the\nvalue of the spring constant for the molecule-electrode chemical bond and\nelectronic coupling strength to the corresponding electrode is critical for the\nappearance of structural instabilities and, consequently, telegraphic switching\nin the electric current. The range of model parameters is identified to observe\nstructurally stable molecular junctions as well as various different kinds of\ncurrent-induced telegraphic switching. The interfacial structural instabilities\nare also quantified based on current noise calculations."
    },
    {
        "anchor": "Eddy current effects in the magnetization dynamics of ferromagnetic\n  metal nanoparticles: We develop an analytical model for describing the magnetization dynamics in\nferromagnetic metal nanoparticles, which is based on the coupled system of the\nLandau-Lifshitz-Gilbert (LLG) and Maxwell equations. By solving Maxwell's\nequations in the quasi-static approximation and finding the magnetic field of\neddy currents, we derive the closed LLG equation for the magnetization that\nfully accounts for the effects of conductivity. We analyze the difference\nbetween the LLG equations in metallic and dielectric nanoparticles and show\nthat these effects can strongly influence the magnetization dynamics. As an\nexample illustrating the importance of eddy currents, the phenomenon of\nprecessional switching of magnetization is considered.",
        "positive": "A multivariate approach to single-molecule thermopower and electric\n  conductance measurements: We report a method using scanning tunnelling microscope single molecular\nbreak junction to simultaneously measure and correlate the single-molecule\nthermopower and electrical conductance. In contrast to previously reported\napproaches, it does not require custom-built electronics and takes advantage of\na trace-by-trace calibration of the thermal offset at the Au/Au contact, thus\ngreatly facilitating thermoelectric measurements at the single-molecule level.\nWe report measurements of three molecules:\n1,4-di(4-(ethynyl(phenylthioacetate)) benzene, 1,8-octanedithiol, and\n4,4'-bipyridine, and determine single-molecule Seebeck coefficients of 12(3),\n5(2), and -5(2) microV K-1, respectively. Furthermore, the method statistically\ncorrelates the Seebeck voltage offset, electrical conductance, and stretching\ndisplacement of the single-molecule junction, and allows for direct comparison\nwith current-distance spectroscopy results obtained at constant bias."
    },
    {
        "anchor": "Weyl points on non-orientable manifolds: Weyl fermions are hypothetical chiral particles that can also manifest as\nexcitations near three-dimensional band crossing points in lattice systems.\nThese quasiparticles are subject to the Nielsen-Ninomiya \"no-go\" theorem when\nplaced on a lattice, requiring the total chirality across the Brillouin zone to\nvanish. This constraint results from the topology of the (orientable) manifold\non which they exist. Here, we ask to what extent the concepts of topology and\nchirality of Weyl points remain well-defined when the underlying manifold is\nnon-orientable. We show that the usual notion of chirality becomes ambiguous in\nthis setting, allowing for systems with a non-zero total chirality.\nFurthermore, we discover that Weyl points on non-orientable manifolds carry an\nadditional $\\mathbb{Z}_2$ topological invariant which satisfies a different\nno-go theorem. We implement such Weyl points by imposing a non-symmorphic\nsymmetry in the momentum space of lattice models. Finally, we experimentally\nrealize all aspects of their phenomenology in a photonic platform with\nsynthetic momenta. Our work highlights the subtle but crucial interplay between\nthe topology of quasiparticles and of their underlying manifold.",
        "positive": "Spontaneous emission of a quantum emitter near a Chern insulator:\n  interplay of time reversal symmetry breaking and van Hove singularity: We consider the generic problem of a two-level quantum emitter near a\ntwo-dimensional Chern insulator in the dipole approximation, and study how the\nfrequency-dependent response and electronic density of states of the insulator\nmodifies the transition rate of the emitter between the ground and excited\nlevels. To this end, we obtain the full real-frequency behavior of the\nconductivity tensor by performing a tight-binding calculation based on the\nQi-Wu-Zhang model and using a Kubo formula, and derive the full electromagnetic\nGreen tensor of the system, which breaks Onsager reciprocity. This enables us\nto find that for frequencies smaller than the maximum band gap, the system is\nsensitive to time reversal symmetry-breaking, whereas for much larger\nfrequencies the system becomes insensitive, with implications for the\ndiscrimination of the state of a circularly polarised dipole emitter. We also\nstudy the impact of a van Hove singularity on the surface-induced correction to\nthe transition rate, finding that it can enhance its amplitude by a few orders\nof magnitude compared to the case where the conductivity is set to its static\nvalue. By considering configurations in which the dipole is circularly\npolarised or parallel with the surface of the Chern insulator, we find that the\nsurface correction to the transition rate can exhibit a novel decay with sine\nintegral-like oscillations."
    },
    {
        "anchor": "Polaron-Polaritons in the Integer and Fractional Quantum Hall Regimes: Elementary quasi-particles in a two dimensional electron system can be\ndescribed as exciton-polarons since electron-exciton interactions ensures\ndressing of excitons by Fermi-sea electron-hole pair excitations. A relevant\nopen question is the modification of this description when the electrons occupy\nflat-bands and electron-electron interactions become prominent. Here, we\nperform cavity spectroscopy of a two dimensional electron system in the\nstrong-coupling regime where polariton resonances carry signatures of strongly\ncorrelated quantum Hall phases. By measuring the evolution of the polariton\nsplitting under an external magnetic field, we demonstrate the modification of\nelectron-exciton interactions that we associate with phase space filling at\ninteger filling factors and polaron dressing at fractional filling factors. The\nobserved non-linear behavior shows great promise for enhancing\npolariton-polariton interactions.",
        "positive": "Signatures of interactions in the Andreev spectrum of nanowire Josephson\n  junctions: We performed microwave spectroscopy of an InAs nanowire between\nsuperconducting contacts implementing a finite-length, multi-channel Josephson\nweak link. Certain features in the spectra, such as the splitting by spin-orbit\ninteractions of the transition lines among Andreev states, have been already\nunderstood in terms of non-interacting models. However, we identify here\nadditional transitions, which evidence the presence of Coulomb interactions. By\ncombining experimental measurements and model calculations, we reach a\nqualitative understanding of these very rich Andreev spectra."
    },
    {
        "anchor": "Single-parameter non-adiabatic quantized charge pumping: Controlled charge pumping in an AlGaAs/GaAs gated nanowire by\nsingle-parameter modulation is studied experimentally and theoretically.\nTransfer of integral multiples of the elementary charge per modulation cycle is\nclearly demonstrated. A simple theoretical model shows that such a quantized\ncurrent can be generated via loading and unloading of a dynamic quasi-bound\nstate. It demonstrates that non-adiabatic blockade of unwanted tunnel events\ncan obliterate the requirement of having at least two phase-shifted periodic\nsignals to realize quantized pumping. The simple configuration without multiple\npumping signals might find wide application in metrological experiments and\nquantum electronics.",
        "positive": "Anisotropies and magnetic phase transitions in insulating\n  antiferromagnets determined by a Spin-Hall magnetoresistance probe: We demonstrate that we can determine the antiferromagnetic anisotropies and\nthe bulk Dzyaloshinskii-Moriya fields of the insulating iron oxide hematite,\n{\\alpha}-Fe2O3, using a surface sensitive spin-Hall magnetoresistance (SMR)\ntechnique. We develop an analytical model that in combination with SMR\nmeasurements, allow for the identification of the material parameters of this\nprototypical antiferromagnet over a wide range of temperatures and magnetic\nfield values. Using devices with different orientations, we demonstrate that\nthe SMR response strongly depends on the direction of the charge current with\nrespect to the magneto-crystalline anisotropies axis. We show that we can\nextract the anisotropies over a wide temperature range including across the\nMorin phase transition. We observe that the electrical response is dominated by\nthe orientation of the antiferromagnetic N\\'eel order parameter, rather than by\nthe emergent weak magnetic moment. Our results highlight that the surface\nsensitivity of the SMR allows accessing the magnetic anisotropies of\nantiferromagnetic crystals and in particular thin films where other methods to\ndetermine anisotropies such as bulk-sensitive magnetic susceptibility\nmeasurements do not provide sufficient sensitivity."
    },
    {
        "anchor": "Excitations of the ferroelectric order: We identify the bosonic excitations in ferroelectrics that carry electric\ndipoles from the phenomenological Landau-Ginzburg-Devonshire theory. The\n\"ferron\" quasi-particles emerge from the concerted action of anharmonicity and\nbroken inversion symmetry. In contrast to magnons, the transverse excitations\nof the magnetic order, the ferrons in displacive ferroelectrics are\nlongitudinal with respect to the ferroelectric order. Based on the ferron\nspectrum, we predict temperature dependent pyroelectric and electrocaloric\nproperties, electric-field-tunable heat and polarization transport, and\nferron-photon hybridization.",
        "positive": "Van der Waals torque and force between anisotropic topological insulator\n  slabs: We investigate the character of the van der Waals (vdW) torque and force\nbetween two coplanar and dielectrically anisotropic topological insulator (TI)\nslabs separated by a vacuum gap in the non-retardation regime, where the optic\naxes of the slabs are each perpendicular to the normal direction to the\nslab-gap interface and also generally differently oriented from each other. We\nfind that in addition to the magnetoelectric coupling strength, the anisotropy\ncan also influence the sign of the vdW force, viz., a repulsive vdW force can\nbecome attractive if the anistropy is increased sufficiently. In addition, the\nvdW force oscillates as a function of the angular difference between the optic\naxes of the TI slabs, being most repulsive/least attractive (least\nrepulsive/most attractive) for angular differences that are integer\n(half-integer) multiples of $\\pi$. Our third finding is that the vdW torque for\nTI slabs is generally weaker than that for ordinary dielectric slabs. Our work\nprovides the first instance in which the vector potential appears in a\ncalculation of the vdW interaction for which the limit is non-retarded or\nstatic."
    },
    {
        "anchor": "Transport properties of p-type metal-oxide-semiconductor inversion layer\n  in (110) and (111) silicon channel under uniaxial stress: Valence subband and transport properties of p-type metal-oxide-semiconductor\n(PMOS) inversion layer in uniaxially strained (110) and (111) Si channel have\nbeen studied theoretically in this work. Equal energy lines, carrier\nconcentration effective mass, conductivity effective mass, and mobility are\ncalculated based on Luttinger-Kohn Hamiltonian [16]. Three compact expressions\nof scattering rate are derived in this paper. The direction of applied uniaxial\nstresses considered is in either parallel or perpendicular to channel. My\nresults show mobility is very sensitive to effective mass under different\nstresses. The favorable mobility directions are found in (110) system with -3\nGPa stress parallel to channel and +3 GPa stress perpendicular to channel.",
        "positive": "Vanishing fine structure splittings in telecom wavelength quantum dots\n  grown on (111)A surfaces by droplet epitaxy: The emission cascade of a single quantum dot is a promising source of\nentangled photons. A prerequisite for this source is the use of a symmetric dot\nanalogous to an atom in a vacuum, but the simultaneous achievement of\nstructural symmetry and emission in a telecom band poses a challenge. Here we\nreport the growth and characterization of highly symmetric InAs/InAlAs quantum\ndots self-assembled on C3v symmetric InP(111)A. The broad emission spectra\ncover the O (1.3 micron-m), C (1.55 micron-m), and L (1.6 micron-m) telecom\nbands. The distribution of the fine-structure splittings is considerably\nsmaller than those reported in previous works on dots at similar wavelengths.\nThe presence of dots with degenerate exciton lines is further confirmed by the\noptical orientation technique. Thus, our dot systems are expected to serve as\nefficient entangled photon emitters for long-distance fiber-based quantum key\ndistribution."
    },
    {
        "anchor": "Nonperturbative quasi-classical theory of the nonlinear electrodynamic\n  response of graphene: An electromagnetic response of a single graphene layer to a uniform,\narbitrarily strong electric field $E(t)$ is calculated by solving the kinetic\nBoltzmann equation within the relaxation-time approximation. The theory is\nvalid at low (microwave, terahertz, infrared) frequencies satisfying the\ncondition $\\hbar\\omega\\lesssim 2E_F$, where $E_F$ is the Fermi energy. We\ninvestigate the saturable absorption and higher harmonics generation effects,\nas well as the transmission, reflection and absorption of radiation incident on\nthe graphene layer, as a function of the frequency and power of the incident\nradiation and of the ratio of the radiative to scattering damping rates. We\nshow that the optical bistability effect, predicted in Phys. Rev. B 90, 125425\n(2014) on the basis of a perturbative approach, disappears when the problem is\nsolved exactly. We show that, under the action of a high-power radiation\n($\\gtrsim 100$ kW/cm$^2$) both the reflection and absorption coefficients\nstrongly decrease and the layer becomes transparent.",
        "positive": "Observation of Intra- and Inter-band Transitions in the Optical Response\n  of Graphene: The optical conductivity of freely suspended graphene was examined under\nnon-equilibrium conditions using femtosecond pump-probe spectroscopy. We\nobserved a conductivity transient that varied strongly with the electronic\ntemperature, exhibiting a crossover from enhanced to decreased absorbance with\nincreasing pump fluence. The response arises from a combination of bleaching of\nthe inter-band transitions by Pauli blocking and induced absorption from the\nintra-band transitions of the carriers. The latter dominates at low electronic\ntemperature, but, despite an increase in Drude scattering rate, is overwhelmed\nby the former at high electronic temperature. The time-evolution of the optical\nconductivity in all regimes can described in terms of a time-varying electronic\ntemperature."
    },
    {
        "anchor": "Experimental verification of electro-refractive phase modulation in\n  graphene: Graphene has been considered as a promising material for opto-electronic\ndevices, because of its tunable and wideband optical properties. In this work,\nwe demonstrate electro-refractive phase modulation in graphene at wavelengths\nfrom 1530 to 1570 nm. By integrating a gated graphene layer in a\nsilicon-waveguide based Mach-Zehnder interferometer, the key parameters of a\nphase modulator like change in effective refractive index, insertion loss and\nabsorption change are extracted. These experimentally obtained values are well\nreproduced by simulations and design guidelines are provided to make graphene\ndevices competitive to contemporary silicon based phase modulators for on-chip\napplications.",
        "positive": "Topological Superfluid Transition Induced by Periodically Driven Optical\n  Lattice: We propose a scenario to create topological superfluid in a periodically\ndriven two-dimensional square optical lattice. We study the phase diagram of a\nspin-orbit coupled s-wave pairing superfluid in a periodically driven\ntwo-dimensional square optical lattice. We find that a phase transition from a\ntrivial superfluid to a topological superfluid occurs when the potentials of\nthe optical lattices are periodically changed. The topological phase is called\nFloquet topological superfluid and can host Majorana fermions."
    },
    {
        "anchor": "Chiral and Non-Chiral Edge States in Quantum Hall Systems with Charge\n  Density Modulation: We consider a system of weakly coupled wires with quantum Hall effect (QHE)\nand in the presence of a spatially periodic modulation of the chemical\npotential along the wire, equivalent to a charge density wave (CDW). We\ninvestigate the competition between the two effects which both open a gap. We\nshow that by changing the ratio between the amplitudes of the CDW modulation\nand the tunneling between wires, one can switch between non-topological\nCDW-dominated phase to topological QHE-dominated phase. Both phases host edge\nstates of chiral and non-chiral nature robust to on-site disorder. However,\nonly in the topological phase, the edge states are immune to disorder in the\nphase shifts of the CDWs. We provide analytical solutions for filling factor\n$\\nu=1$ and study numerically effects of disorder as well as present numerical\nresults for higher filling factors.",
        "positive": "Giant paramagnetism induced valley polarization of electrons in\n  charge-tunable monolayer MoSe2: For applications exploiting the valley pseudospin degree of freedom in\ntransition metal dichalcogenide monolayers, efficient preparation of electrons\nor holes in a single valley is essential. Here, we show that a magnetic field\nof 7 Tesla leads to a near-complete valley polarization of electrons in MoSe2\nmonolayer with a density 1.6x10^{12} cm^{-2}; in the absence of exchange\ninteractions favoring single-valley occupancy, a similar degree of valley\npolarization would have required a pseudospin g-factor exceeding 40. To\ninvestigate the magnetic response, we use polarization resolved\nphotoluminescence as well as resonant reflection measurements. In the latter,\nwe observe gate voltage dependent transfer of oscillator strength from the\nexciton to the attractive-Fermi-polaron: stark differences in the spectrum of\nthe two light helicities provide a confirmation of valley polarization. Our\nfindings suggest an interaction induced giant paramagnetic response of MoSe2,\nwhich paves the way for valleytronics applications."
    },
    {
        "anchor": "Spin and charge pumping in magnetic tunnel junctions with precessing\n  magnetization: A nonequilibrium Green function approach: We study spin and charge currents pumped by precessing magnetization of a\nsingle ferromagnetic layer within F|I|N or F|I|F (F-ferromagnet; I-insulator;\nN-normal-metal) multilayers of nanoscale thickness attached to two normal metal\nelectrodes with no applied bias voltage between them. Both simple\none-dimensional model, consisting of a single precessing spin and a potential\nbarrier as the \"sample,\" and realistic three-dimensional devices are\ninvestigated. In the rotating reference frame, where the magnetization appears\nto be static, these junctions are mapped onto a four-terminal dc circuit whose\neffectively half-metallic ferromagnetic electrodes are biased by the frequency\n$\\hbar \\omega/e$ of microwave radiation driving magnetization precession at the\nferromagnetic resonance (FMR) conditions. We show that pumped spin current in\nF|I|F junctions, diminished behind the tunnel barrier and increased in the\nopposite direction, is filtered into charge current by the second $F$ layer to\ngenerate dc pumping voltage of the order of $\\sim 1$ $\\mu$V (at FMR frequency\n$\\sim 10$ GHz) in an open circuit. In F|I|N devices, several orders of\nmagnitude smaller charge current and the corresponding dc voltage appear\nconcomitantly with the pumped spin current due to barrier induced asymmetry in\nthe transmission coefficients connecting the four electrodes in the rotating\nframe picture of pumping.",
        "positive": "Reorientation of the stripe Phase of 2D Electrons by a Minute Density\n  Modulation: Interacting two-dimensional electrons confined in a GaAs quantum well exhibit\nisotropic transport when the Fermi level resides in the first excited ($N=1$)\nLandau level. Adding an in-plane magnetic field ($B_{||}$) typically leads to\nan anisotropic, stripe-like (nematic) phase of electrons with the stripes\noriented perpendicular to the $B_{||}$ direction. Our experimental data reveal\nhow a periodic density modulation, induced by a surface strain grating from\nstrips of negative electron-beam resist, competes against the $B_{||}$-induced\norientational order of the stripe phase. Even a minute ($<0.25\\%$) density\nmodulation is sufficient to reorient the stripes along the direction of the\nsurface grating."
    },
    {
        "anchor": "Small-angle neutron scattering by spatially inhomogeneous ferromagnets\n  with a nonzero average uniaxial anisotropy: Micromagnetic small-angle neutron scattering theory is well established for\nanalyzing spin-misalignment scattering data of bulk ferromagnets. Here, this\ntheory is extended to allow for a global uniaxial magnetic anisotropy (texture)\nof the material, in addition to the already included random zero-average local\nanisotropy. Macroscopic cross-sections and spin-misalignment response functions\nare computed analytically for several practically relevant mutual anisotropy\nand external magnetic field orientations in both parallel and perpendicular\nscattering geometries for field magnitudes both above and below the rotational\nsaturation. Some of these expressions are tested on published experimental data\nof magnetic-field-annealed Vitroperm and plastically-deformed Ni, allowing to\ndetermine the corresponding global uniaxial anisotropy quality factors.",
        "positive": "Magnetic tuning of the tunnel coupling in an optically active quantum\n  dot molecule: Self-assembled optically active quantum dot molecules (QDMs) allow the\ncreation of protected qubits via singlet-triplet spin states. The qubit energy\nsplitting of these states is defined by the tunnel coupling strength and is,\ntherefore, determined by the potential landscape and thus fixed during growth.\nApplying an in-plane magnetic field increases the confinement of the hybridized\nwave functions within the quantum dots, leading to a decrease of the tunnel\ncoupling strength. We achieve a tuning of the coupling strength by\n$(53.4\\pm1.7)$ %. The ability to fine-tune this coupling is essential for\nquantum network and computing applications that require quantum systems with\nnear identical performance."
    },
    {
        "anchor": "Control of dimer chain topology by Rashba-Dresselhaus spin-orbit\n  coupling: We study theoretically a dimer chain in the presence of Rashba-Dresselhaus\nspin-orbit coupling (RDSOC) with equal strength. We show that the RDSOC can be\ndescribed as a synthetic gauge field that controls not only the magnitude but\nalso the sign of tunneling coefficients between sites. This allows to emulate\nnot only a Su-Schrieffer-Heeger chain which is commonly implemented in various\nplatforms, but also, all energy spectra of the transverse field Ising model\nwith both ferromagnetic and antiferromagnetic coupling. We simulate a realistic\nimplementation of these effective Hamiltonians based on liquid crystal\nmicrocavities. In that case, the RDSOC can be switched on and off by an applied\nvoltage, which controls the band topology, the existence and characteristics of\ntopological edge states, or the nature of the ground state. This setting is\npromising for topological photonics applications and from a quantum simulation\nperspective.",
        "positive": "Nanomechanical manipulation of superconducting charge-qubit quantum\n  networks: We suggest a nanoelectromechanical setup and corresponding time-protocol for\ncontrolling parameters in order to demonstrate nanomechanical manipulation of\nsuperconducting charge-qubit quantum network. We illustrate it on an example\nreflecting important task for quantum information processing - transmission of\nquantum information between two charge-qubits facilitated by nanomechanics. The\nsetup is based on terminals utilizing the AC Josephson effect between bias\nvoltage-controlled bulk superconductors and mechanically vibrating mesoscopic\nsuperconducting grain in the regime of the Cooper pair box, controlled by the\ngate voltage. The described manipulation of quantum network is achieved by\ntransduction of quantum information between charge-qubits and intentionally\nbuilt nanomechanical coherent states, which facilitate its transmission between\nqubits. This performance is achieved using quantum entanglement between\nelectrical and mechanical states."
    },
    {
        "anchor": "Feedback cooling of cantilever motion using a quantum point contact\n  transducer: We use a quantum point contact (QPC) as a displacement transducer to measure\nand control the low-temperature thermal motion of a nearby micromechanical\ncantilever. The QPC is included in an active feedback loop designed to cool the\ncantilever's fundamental mechanical mode, achieving a squashing of the QPC\nnoise at high gain. The minimum achieved effective mode temperature of 0.2 K\nand the displacement resolution of 10^(-11) m/Hz^(1/2) are limited by the\nperformance of the QPC as a one-dimensional conductor and by the cantilever-QPC\ncapacitive coupling.",
        "positive": "Screw dislocations in cubic chiral magnets: Helimagnets realize an effective lamellar ordering that supports disclination\nand dislocation defects. Here, we investigate the micromagnetic structure of\nscrew dislocation lines in cubic chiral magnets using analytical and numerical\nmethods. The far field of these dislocations is universal and classified by an\ninteger strength $\\nu$ that characterizes the winding of magnetic moments. We\ndemonstrate that a rich variety of dislocation-core structures can be realized\neven for the same strength $\\nu$. In particular, the magnetization at the core\ncan be either smooth or singular. We present a specific example with $\\nu = 1$\nfor which the core is composed of a chain of singular Bloch points. In general,\nscrew dislocations carry a non-integer but finite skyrmion charge so that they\ncan be efficiently manipulated by spin currents."
    },
    {
        "anchor": "Probing two-electron multiplets in bilayer graphene quantum dots: We report on finite bias spectroscopy measurements of the two-electron\nspectrum in a gate defined bilayer graphene (BLG) quantum dot for varying\nmagnetic fields. The spin and valley degree of freedom in BLG give rise to\nmultiplets of 6 orbital symmetric and 10 orbital anti-symmetric states. We find\nthat orbital symmetric states are lower in energy and separated by $\\approx 0.4\n- 0.8$ meV from orbital anti-symmetric states. The symmetric multiplet exhibits\nan additional energy splitting of its 6 states of $\\approx 0.15 - 0.5$ meV due\nto lattice scale interactions. The experimental observations are supported by\ntheoretical calculations, which allow to determine that inter-valley scattering\nand 'current-current' interaction constants are of the same magnitude in BLG.",
        "positive": "Imaging the dynamics of individual hydrogen atom intercalated between\n  two graphene sheets: The interlayer gallery between two adjacent sheets of van der Waals materials\nis expected to modify properties of atoms and molecules confined at the atomic\ninterfaces. Here, we directly image individual hydrogen atom intercalated\nbetween two graphene sheets and investigate its dynamics by scanning tunnelling\nmicroscope (STM). The intercalated hydrogen atom is found to be remarkably\ndifferent from atomic hydrogen chemisorbed on external surface of graphene. Our\nSTM measurements, complemented by first-principles calculations, show that the\nhydrogen atom intercalated between two graphene sheets has dramatically reduced\npotential barriers for elementary migration steps. Especially, the confined\natomic hydrogen dissociation energy from graphene is reduced to 0.34 eV, which\nis only about a third of a hydrogen atom chemisorbed on graphene. This offers a\nunique platform for direct imaging of the atomic dynamics of confined atoms.\nOur results suggest that the atomic interfaces of van der Waals materials may\nprovide a confined environment to tune the interfacial chemical reactions."
    },
    {
        "anchor": "Stacking and gate tunable topological flat bands, gaps and anisotropic\n  strip patterns in twisted trilayer graphene: Trilayer graphene with a twisted middle layer has recently emerged as a new\nplatform exhibiting correlated phases and superconductivity near its magic\nangle. A detailed characterization of its electronic structure in the parameter\nspace of twist angle $\\theta$, interlayer potential difference $\\Delta$, and\ntop-bottom layer stacking $\\tau$ reveals that flat bands with large Coulomb\nenergy vs bandwidth $U/W > 1$ are expected within a range of $\\pm 0.2^{\\circ}$\nnear $\\theta \\simeq1.5^{\\circ}$ and $\\theta \\simeq1.2^{\\circ}$ for $\\tau_{\\rm\nAA}$ top-bottom layer stacking, between a wider $1^{\\circ} \\sim 1.7^{\\circ}$\nrange for $\\tau_{\\rm AB}$ stacking, whose bands often have finite valley Chern\nnumbers thanks to the opening of primary and secondary band gaps in the\npresence of a finite $\\Delta$, and below $\\theta \\lesssim 0.6^{\\circ}$ for all\n$\\tau$ considered. The largest $U/W$ ratios are expected at the magic angle\n$\\sim 1.5^{\\circ}$ when $|\\Delta| \\sim 0$~meV for AA, and slightly below near\n$\\sim 1.4^{\\circ}$ for finite $|\\Delta| \\sim 25$~meV for AB stackings, and near\n$\\theta \\sim 0.4^{\\circ}$ for both stackings. When ${\\tau}$ is the saddle point\nstacking vector between AB and BA we observe pronounced anisotropic local\ndensity of states (LDOS) strip patterns with broken triangular rotational\nsymmetry. We present optical conductivity calculations that reflect the changes\nin the electronic structure introduced by the stacking and gate tunable system\nparameters.",
        "positive": "Singular-Value Statistics of Non-Hermitian Random Matrices and Open\n  Quantum Systems: The spectral statistics of non-Hermitian random matrices are of importance as\na diagnostic tool for chaotic behavior in open quantum systems. Here, we\ninvestigate the statistical properties of singular values in non-Hermitian\nrandom matrices as an effective measure of quantifying dissipative quantum\nchaos. By means of Hermitization, we reveal the unique characteristics of the\nsingular-value statistics that distinguish them from the complex-eigenvalue\nstatistics, and establish the comprehensive classification of the\nsingular-value statistics for all the 38-fold symmetry classes of non-Hermitian\nrandom matrices. We also analytically derive the singular-value statistics of\nsmall random matrices, which well describe those of large random matrices in\nthe similar spirit to the Wigner surmise. Furthermore, we demonstrate that\nsingular values of open quantum many-body systems follow the random-matrix\nstatistics, thereby identifying chaos and nonintegrability in open quantum\nsystems. Our work elucidates that the singular-value statistics serve as a\nclear indicator of symmetry and lay a foundation for statistical physics of\nopen quantum systems."
    },
    {
        "anchor": "Nonlinear optical properties and Kerr nonlinearity of Rydberg excitons\n  in Cu$_2$O quantum wells: The quantum confiment of Rydberg excitons (REs) in quantum structures opens\nthe way towards considering nonlinear interactions in such systems. We present\na theoretical calculation of optical functions in the case of a nonlinear\ncoupling between REs in a quantum well with an electromagnetic wave. Using the\nReal Density Matrix Approach (RDMA), the analytical expressions for a linear\nand nonlinear absorption are derived and numerical calculations for Cu$_2$0\nquantum wells are performed. The results indicate the conditions in which\nquantum well confinement states can be observed in linear and nonlinear optical\nspectra. The Kerr nonlinearity and self-phase modulation in such a system are\nstudied. The effect of Rydberg blockade and the associated optical bleaching\nare also discussed and confronted with available experimental data.",
        "positive": "Ultralong Copper Phthalocyanine Nanowires with New Crystal Structure and\n  Broad Optical Absorption: The development of molecular nanostructures plays a major role in emerging\norganic electronic applications, as it leads to improved performance and is\ncompatible with our increasing need for miniaturisation. In particular,\nnanowires have been obtained from solution or vapour phase and have displayed\nhigh conductivity, or large interfacial areas in solar cells. In all cases\nhowever, the crystal structure remains as in films or bulk, and the\nexploitation of wires requires extensive post-growth manipulation as their\norientations are random. Here we report copper phthalocyanine (CuPc) nanowires\nwith diameters of 10-100 nm, high directionality and unprecedented aspect\nratios. We demonstrate that they adopt a new crystal phase, designated\neta-CuPc, where the molecules stack along the long axis. The resulting high\nelectronic overlap along the centimetre length stacks achieved in our wires\nmediates antiferromagnetic couplings and broadens the optical absorption\nspectrum. The ability to fabricate ultralong, flexible metal phthalocyanine\nnanowires opens new possibilities for applications of these simple molecules."
    },
    {
        "anchor": "Origin of Discrepancies in Inelastic Electron Tunneling Spectra of\n  Molecular Junctions: We report inelastic electron tunneling spectroscopy (IETS) of multilayer\nmolecular junctions with and without incorporated metal nano-particles. The\nincorporation of metal nanoparticles into our devices leads to enhanced IET\nintensity and a modified line-shape for some vibrational modes. The enhancement\nand line-shape modification are both the result of a low lying hybrid metal\nnanoparticle-molecule electronic level. These observations explain the apparent\ndiscrepancy between earlier IETS measurements of alkane thiolate junctions by\nKushmerick \\emph{et al.} [Nano Lett. \\textbf{4}, 639 (2004)] and Wang \\emph{et\nal.} [Nano Lett. \\textbf{4}, 643 (2004)].",
        "positive": "Possibility of reflectionless tunneling crossed transport at normal\n  metal / superconductor double interfaces: We investigate one dimensional models (the Blonder, Tinkham, Klapwijk model\nand a tight-binding model) of non local transport at normal metal /\nsuperconductor (NS) double interfaces. We find a negative elastic cotunneling\ncrossed conductance, strongly enhanced by additional scatterers away from the\ninterfaces, suggesting the possibility of reflectionless tunneling non local\ntransport at double NS interfaces with contacts having a sufficiently small\nextension."
    },
    {
        "anchor": "Inverse counting statistics based on generalized factorial cumulants: We propose a procedure to reconstruct characteristic features of an unknown\nstochastic system from the long-time full counting statistics of some of the\nsystem's transitions that are monitored by a detector. The full counting\nstatistics is conveniently parametrized by so-called generalized factorial\ncumulants. Taking only a few of them as input information is sufficient to\nreconstruct important features such as the lower bound of the system dimension\nand the full spectrum of relaxation rates. The use of generalized factorial\ncumulants reveals system dimensions and rates that are hidden for ordinary\ncumulants. We illustrate the inverse counting-statistics procedure for two\nmodel systems: a single-level quantum dot in a Zeeman field and a\nsingle-electron box subjected to sequential and Andreev tunneling.",
        "positive": "Inversion symmetric non-Hermitian Chern insulator: We propose a two-dimensional non-Hermitian Chern insulator with inversion\nsymmetry, which is anisotropic and has staggered gain and loss in both x and y\ndirections. In this system, conventional bulk-boundary correspondence holds.\nThe Chern number is a topological invariant that accurately predicts the\ntopological phase transition and the existence of helical edge states in the\ntopologically nontrivial gapped phase. In the gapless phase, the band touching\npoints are isolated and protected by the symmetry. The degenerate points alter\nthe system topology, and the exceptional points can destroy the existence of\nhelical edge states. Topologically protected helical edge states exist in the\ngapless phase for the system under open boundary condition in one direction,\nwhich are predicted by the winding number associated with the vector field of\naverage values of Pauli matrices. The winding number also identifies the\ndetaching points between the edge states and the bulk states in the energy\nbands. The non-Hermiticity also supports a topological phase with zero Chern\nnumber, where a pair of in-gap helical edge states exists. Our findings provide\ninsights into the symmetry protected non-Hermitian topological insulators."
    },
    {
        "anchor": "Spin pumping from antiferromagnetic insulator spin-orbit-proximitized by\n  adjacent heavy metal: A first-principles Floquet-nonequilibrium Green's\n  function study: Motivated by recent experiments [P. Vaidya {\\em et al.}, Science {\\bf 368},\n160 (2020)] on spin pumping from sub-THz radiation-driven uniaxial\nantiferromagnetic insulator (AFI) MnF$_2$ into heavy metal (HM) Pt hosting\nstrong spin-orbit (SO) coupling, we compute and compare pumped spin currents in\nCu/MnF$_2$/Cu and Pt/MnF$_2$/Cu heterostructures. Recent theories of spin\npumping by AFI have relied on simplistic Hamiltonians (such as tight-binding)\nand the scattering approach to quantum transport yielding the so-called\ninterfacial spin mixing conductance (SMC), but the concept of SMC ceases to be\napplicable when SO coupling is present directly at the interface. In contrast,\nwe use more general first-principles quantum transport approach which combines\nnoncollinear density functional theory with Floquet-nonequilibrium Green's\nfunctions in order to take into account: {\\em SO-proximitized AFI} as a new\ntype of quantum material, different from isolated AFI and brought about by AFI\nhybridization with adjacent HM layer; SO coupling at interfaces; and evanescent\nwavefunctions penetrating from Pt or Cu into AFI layer to make its interfacial\nregion {\\em conducting} rather than insulating as in the original AFI. The DC\ncomponent of pumped spin current $I_\\mathrm{DC}^{S_z}$ vs. precession cone\nangle $\\theta_{\\vb*{l}}$ of the N\\'eel vector $\\vb*{l}$ of AFI {\\em does not}\nfollow putative $I^{S_z}_\\mathrm{DC} \\propto \\sin^2 \\theta_{\\vb*{l}}$, except\nfor very small angles $\\theta_{\\vb*{l}} \\lesssim 10^\\circ$ for which we can\ndefine an {\\em effective} SMC from the prefactor and find that it doubles from\nMnF$_2$/Cu to MnF$_2$/Pt interface. In addition, the angular dependence\n$I^{S_z}_\\mathrm{DC}(\\theta_{\\vb*{l}})$ differs for opposite directions of\nprecession of the N\\'{e}el vector, leading to twice as large SMC for the\nright-handed than for the left-handed chirality of the precession mode.",
        "positive": "Unconventional Josephson Effect in Hybrid Superconductor-Topological\n  Insulator Devices: We report on transport properties of Josephson junctions in hybrid\nsuperconducting-topological insulator devices, which show two striking\ndepartures from the common Josephson junction behavior: a characteristic energy\nthat scales inversely with the width of the junction, and a low characteristic\nmagnetic field for suppressing supercurrent. To explain these effects, we\npropose a phenomenological model which expands on the existing theory for\ntopological insulator Josephson junctions."
    },
    {
        "anchor": "Quantum Hall effect at half-filled Landau level: Pairing of composite\n  fermions: We discuss the possibility of the quantum Hall effect at half-filled Landau\nlevel in terms of the pairing of the composite fermions. In the absence of\nCoulomb energy, we show that the ground state of the system is described by the\n{\\it p}-wave BCS pairing state of composite fermions. When the ratio $\\alpha\n\\equiv (e^2/\\epsilon \\ell_B)/\\epsilon_F$ ($\\ell_B$ : the magnetic length,\n$\\epsilon_F$ : Fermi energy of the composite fermions) is larger than a\ncritical value $\\alpha_c \\sim 8.2$ the gap of the pairing state vanishes.\nHowever, $\\alpha$ remains less than $\\alpha_c$ if $\\hbar \\omega_c \\gg\ne^2/\\epsilon \\ell_B$ holds. Then in this situation it is possible that the\npairing state which results in the quantum Hall effect occurs. The effect of\nthe real spin degrees of freedom and the Zeeman energy is also discussed.",
        "positive": "Spin Hall utilizing U(1) and SU(2) gauge fields: We propose a two-dimensional electron gas (2DEG) system in which an external\nmagnetic (B) field with a small chirality is applied to provide a topological\nU(1) U(1) gauge field that separates conduction electrons of opposite spins in\nthe transverse direction. Additionally, the vertical electric (E) field in the\n2DEG, together with spin-orbit coupling, produces a SU(2) gauge field which\nreinforces / opposes the effect of the topological gauge. The system thus\nprovides a tunable spin Hall effect, where an applied gate voltage on the 2DEG\ncan be used to modulate the transverse spin current. As this method leads to\nthe enhancement or cancellation of intrinsic spin Hall, it naturally\ndistinguishes the extrinsic from the intrinsic effect."
    },
    {
        "anchor": "360\u00b0 Domain Walls: Stability, Magnetic Field and Electric Current\n  Effects: The formation of 360{\\deg} magnetic domain walls (360DWs) in Co and Ni80Fe20\nthin film wires was demonstrated experimentally for different wire widths, by\nsuccessively injecting two 180{\\deg} domain walls (180DWs) into the wire. For\nnarrow wires (less than 50 nm wide for Co), edge roughness prevented the\ncombination of the 180DWs into a 360DW, and for wide wires (200 nm for Co) the\n360DW collapsed, but over an intermediate range of wire widths, reproducible\n360DW formation occurred. The annihilation and dissociation of 360DWs was\ndemonstrated by applying a magnetic field parallel to the wire, showing that\nannihilation fields were several times higher than dissociation fields in\nagreement with micromagnetic modeling. The annihilation of a 360DW by current\npulsing was demonstrated.",
        "positive": "Interacting One-Dimensional Electrons Driven by Two-Dimensional\n  Reservoir Electrons: We derive an effective 1D theory from the Hamiltonian of the 3D system which\nconsists of a mesoscopic conductor and reservoirs. We assume that the many-body\ninteraction have the same magnitude in the conductor as that in the reservoirs,\nin contrast to the previous theories which made the ad hoc assumption that the\nmany-body interaction were absent in the reservoirs. We show the following: (i)\nThe effective potentials of impurities and two-body interaction for the 1D\nmodes become weaker as $x$ goes away from the conductor. (ii) On the other\nhand, the interaction between the 1D and the reservoir modes is important in\nthe reservoir regions, where the reservoir modes excite and attenuate the 1D\nmodes through the interaction. (iii) As a result, the current $\\hat I_1$ of the\n1D modes is not conserved, whereas the total current $\\hat I$ is of course\nconserved. (iv) For any steady state the total current $\\bra I \\ket$, its\nequilibrium fluctuation $\\bra \\delta I^2 \\ket^{eq}$ at low frequency, and\nnon-equilibrium fluctuation $\\bra \\delta I^2 \\ket^{noneq}$ at low frequency, of\nthe original system are independent of $x$, whereas $\\bra \\delta I^2 \\ket^{eq}$\nand $\\bra \\delta I^2 \\ket^{noneq}$ at higher frequencies may depend on $x$. (v)\nUtilizing this property, we can evaluate $\\bra I \\ket$, $\\bra \\delta I^2\n\\ket^{eq}$, and $\\bra \\delta I^2 \\ket^{noneq}$ at low frequency from those of\nthe 1D current $\\hat I_1$. (vi) In general, the transmittance $T$ in the\nLandauer formula should be evaluated from a single-body Hamiltonian which\nincludes a Hartree potential created by the density deformation which is caused\nby the external bias."
    },
    {
        "anchor": "Conductance distribution in disordered quantum wires: Crossover between\n  the metallic and insulating regimes: We calculate the distribution of the conductance P(g) for a\nquasi-one-dimensional system in the metal to insulator crossover regime, based\non a recent analytical method valid for all strengths of disorder. We show the\nevolution of P(g) as a function of the disorder parameter from a insulator to a\nmetal. Our results agree with numerical studies reported on this problem, and\nwith analytical results for the average and variance of g.",
        "positive": "Magnetic frustration and fractionalization in oligo(indenoindenes): Poly(indenoindenes) are {\\pi}-conjugated ladder carbon polymers with\nalternating hexagons and pentagons hosting one unpaired electron for each\nfive-membered ring in the open-shell limit. Here we study the main magnetic\ninteractions that are present in finite oligo(indenoindenes) (OInIn),\nclassifying the six possible isomers in two different classes of three isomers\neach. One class can be rationalized by frustrated S = 1/2 Heisenberg chains,\nwith ferromagnetic interactions between neighbour sites and antiferromagnetic\ninteractions between the next neighbours. The other class is characterized by\nthe more trivial antiferromagnetic order. Employing several levels of theory we\nfurther show that the ground state of one of the isomers is a valence-bond\nsolid (VBS) of ferromagnetic dimers (S = 1). This is topologically similar to\nthat of the Affleck-Kennedy-Lieb-Tasaki (AKLT) model, which is known to show\nfractional S = 1/2 states at the edges."
    },
    {
        "anchor": "Phonon mediated spin relaxation in a moving quantum dot: Doppler shift,\n  Cherenkov radiation, and spin relaxation boom: We study relaxation of a moving spin qubit caused by phonon noise. As we vary\nthe speed of the qubit, we observe several interesting features in spin\nrelaxation and the associated phonon emission, induced by Doppler effect. In\nparticular, in the supersonic regime, the phonons emitted by the relaxing qubit\nis concentrated along certain directions, similar to the shock waves produced\nin classical Cherenkov effect. As the speed of the moving qubit increases from\nthe subsonic regime to the supersonic regime, the qubit experiences a peak in\nthe spin relaxation rate near the speed of sound, which we term a spin\nrelaxation boom in analogy to the classical sonic boom. We also find that the\nmoving spin qubit may have a lower relaxation rate than a static qubit, which\nhints at the possibility of coherence-preserving transportation for a spin\nqubit. While the physics we have studied here has strong classical analogies,\nwe do find that quantum confinement for the spin qubit plays an important role\nin all the phenomena we observe. Specifically, it produces a correction on the\nCherenkov angle, and removes the divergence in relaxation rate at the sonic\nbarrier. It is our hope that our results would encourage further research into\napproaches for transferring and preserving quantum information in spin qubit\narchitectures.",
        "positive": "Edge of a Half-Filled Landau Level: We have investigated the electron occupation number of the edge of a quantum\nHall (QH) droplet at $\\nu=1/2$ using exact diagonalization technique and\ncomposite fermion trial wavefunction. We find that the electron occupation\nnumbers near the edge obey a scaling behavior. The scaling result indicates the\nexistence of a well-defined edge corresponding to the radius of a compact\ndroplet of uniform filling factor 1/2. We find that the occupation number\nbeyond this edge point is substantial, which is qualitatively different from\nthe case of odd-denominator QH states. We relate these features to the\ndifferent ways in which composite fermions occupy Landau levels for odd and\neven denominator states."
    },
    {
        "anchor": "Interlayer Conductance in the Armchair Nanotube -- Zigzag Graphene\n  Ribbon Parallel Contact: Theoretical Proposal of Detection of Wavefunction\n  Growing from the Edge to the Center in the Graphene Ribbon: Sublattices A and B are opposite in the decay direction of the edge state of\nthe zigzag graphene ribbon (ZGR). Detecting exponential growth from the zigzag\nedges to the ZGR center remains challenging. The tight-binding model\ncalculations in this letter reveal that interlayer conductance manifests this\ngrowth in parallel contact with the armchair nanotube. The transfer integrals\nof oblique interlayer bonds are comparable to those of vertical interlayer\nbonds. However, the phase of the ZGR wave function strongly suppresses the\ncontribution of oblique bonds, allowing the selective detection of the growing\ncomponent.",
        "positive": "Large and tunable photo-thermoelectric effect in single-layer MoS2: We study the photoresponse of single-layer MoS2 field-effect transistors by\nscanning photocurrent microscopy. We find that, unlike in many other\nsemiconductors, the photocurrent generation in single-layer MoS2 is dominated\nby the photo-thermoelectric effect and not by the separation of photoexcited\nelectron-hole pairs across the Schottky barriers at the MoS2/electrode\ninterfaces. We observe a large value for the Seebeck coefficient for\nsingle-layer MoS2 that, by an external electric field, can be tuned between\n-4x10^2 uV/K and -1x10^5 uV/K. This large and tunable Seebeck coefficient of\nthe single-layer MoS2 paves the way to new applications of this material such\nas on-chip thermopower generation and waste thermal energy harvesting."
    },
    {
        "anchor": "Two-dimensional magnetotransport in Bi2Te2Se nanoplatelets: Single-crystalline Bi2Te2Se nanoplates with thicknesses between 8 and 30 nm\nand lateral sizes of several micrometers were synthesized by a vapour-solid\ngrowth method. Angle-dependent magnetoconductance measurements on individual\nnanoplates revealed the presence of a two-dimensional weak anti-localization\neffect. In conjunction with gate-dependent charge transport studies performed\nat different temperatures, evidence was gained that this effect originates from\nthe topologically protected surface states of the nanoplates.",
        "positive": "Spatially resolving unconventional interface Landau quantization in a\n  graphene monolayer-bilayer planar junction: Graphene hybrid planar structures consisting of two regions with different\nquantum Hall (QH) states exhibit unusual transport properties1-5, originating\nfrom chiral edge states equilibration at the interface of the two different\nregions6. Here we present a sub-nanometre-resolved scanning tunnelling\nmicroscopy (STM) and spectroscopy (STS) study of a monolayer-bilayer graphene\nplanar junction in the QH regime. The atomically well-defined interface of such\na junction allows us to spatially resolve the interface electronic properties.\nAround the interface, we detect Landau quantization of massless Dirac fermions,\nas expected in graphene monolayer, below the charge neutrality point Nc of the\njunction, whereas unexpectedly, only Landau quantization of massive Dirac\nfermions, as expected in graphene bilayer, is observed above the Nc. The\nobserved unconventional interface Landau quantization arises from the fact that\nthe quantum conductance across the interface is solely determined by the\nminimum filling factors (number of edge modes) in the graphene monolayer and\nbilayer regions of the junction6,7."
    },
    {
        "anchor": "Ice polyamorphism in the minimal Mercedes-Benz model of water: We investigate ice polyamorphism in the context of the two-dimensional\nMercedes-Benz model of water. We find a first-order phase transition between a\ncrystalline phase and a high-density amorphous phase. Furthermore we find a\nreversible transformation between two amorphous structures of high and low\ndensity; however we find this to be a continuous and not an abrupt transition,\nas the low-density amorphous phase does not show structural stability. We\ndiscuss the origin of this behavior and its implications with regard to the\nminimal generic modeling of polyamorphism.",
        "positive": "Microscopic analysis of proximity-induced superconductivity and\n  metallization effects in superconductor-germanium hole nanowires: Low-dimensional germanium hole devices are promising systems with many\npotential applications such as hole spin qubits, Andreev spin qubits, and\nJosephson junctions, and can serve as a basis for the realization of\ntopological superconductivity. This vast array of potential uses for Ge largely\nstems from the exceptionally strong and controllable spin-orbit interaction\n(SOI), ultralong mean free paths, long coherence times, and compatibility with\ncomplementary metal-oxide-semiconductor (CMOS) technology. However, when\nbrought into proximity with a superconductor (SC), metallization normally\ndiminishes many useful properties of a semiconductor, for instance, typically\nreducing the g factor and SOI energy, as well as renormalizing the effective\nmass. In this paper, we consider metallization of a Ge nanowire (NW) in\nproximity to a SC, explicitly taking into account the three-dimensional (3D)\ngeometry of the NW. We find that proximitized Ge exhibits a unique\nphenomenology of metallization effects, where the 3D cross section plays a\ncrucial role. For instance, in contrast to expectations, we find that SOI can\nbe enhanced by strong coupling to the superconductor. We also show that the\nthickness of the NW plays a critical role in determining both the size of the\nproximity-induced pairing potential and metallization effects, since the\ncoupling between the NW and SC strongly depends on the distance of the NW wave\nfunction from the interface with the SC. In the absence of electrostatic\neffects, we find that a sizable gap opens only in thin NWs ($d \\lesssim 3$ nm).\nIn thicker NWs, the wave function must be pushed closer to the SC by\nelectrostatic effects in order to achieve a sizable proximity gap such that the\nrequired electrostatic field strength can simultaneously induce a strong SOI."
    },
    {
        "anchor": "Room-temperature electric field effect and carrier-type inversion in\n  graphene films: The ability to control electronic properties of a material by externally\napplied voltage is at the heart of modern electronics. In many cases, it is the\nso-called electric field effect that allows one to vary the carrier\nconcentration in a semiconductor device and, consequently, change an electric\ncurrent through it. As the semiconductor industry is nearing the limits of\nperformance improvements for the current technologies dominated by silicon,\nthere is a constant search for new, non-traditional materials whose properties\ncan be controlled by electric field. Most notable examples of such materials\ndeveloped recently are organic conductors [1], oxides near a superconducting or\nmagnetic phase transition [2] and carbon nanotubes [3-5]. Here, we describe\nanother system of this kind - thin monocrystalline films of graphite - which\nexhibits a pronounced electric field effect, such that carriers in the\nconductive channel can be turned into either electrons or holes. The films\nremain metallic, continuous and of high quality down to a few atomic layers in\nthickness. The demonstrated ease of preparing such films of nearly macroscopic\nsizes and of their processing by standard microfabrication techniques, combined\nwith submicron-scale ballistic transport even at room temperature, offer a new\ntwo-dimensional system controllable by electric-field doping and provide a\nrealistic promise of device applications.",
        "positive": "Thermoelectric and magneto-transport characteristics of interconnected\n  networks of ferromagnetic nanowires and nanotubes: Macroscopic-scale nanostructures, situated at the interface of nanostructures\nand bulk materials, hold significant promise in the realm of thermoelectric\nmaterials. Nanostructuring presents a compelling avenue for enhancing material\nthermoelectric performance as well as unlocking intriguing nanoscale phenomena,\nincluding spin-dependent thermoelectric effects. This is achieved while\npreserving high power output capabilities and ease of measurements related to\nthe overall macroscopic dimensions. Within this framework, the recently\ndeveloped three-dimensional interconnected nanowire and nanotube networks,\nintegrated into a flexible polymer membrane, emerge as promising candidates for\nmacroscopic nanostructures. The flexibility of these composites also paves the\nway for advances in the burgeoning field of flexible thermoelectrics. In this\nstudy, we demonstrate that the three-dimensional nanowire networks made of\nferromagnetic metals maintain the intrinsic bulk thermoelectric power of their\nbulk constituent even for a diameter reduced to approximately 23 nm.\nFurthermore, we showcase the pioneering magneto-thermoelectric measurements of\nthree-dimensional interconnected nickel nanotube networks. These macroscopic\nmaterials, comprising interconnected nanotubes, enable the development of\nlarge-area devices that exhibit efficient thermoelectric performance, while\ntheir nanoscale tubular structures provide distinctive magneto-transport\nproperties. This research represents a significant step toward harnessing the\npotential of macroscopic nanostructured materials in the field of\nthermoelectrics."
    },
    {
        "anchor": "Micromagnetic modeling of Terahertz oscillations in an antiferromagnetic\n  material driven by spin-Hall effect: The realization of THz sources is a fundamental aspect for a wide range of\napplications. Over different approaches, compact THz oscillators can be\nrealized taking advantage of dynamics in antiferromagnetic (AFMs) thin films\ndriven by spin-Hall effect. Here we perform a systematic study of these THz\noscillators within a full micromagnetic solver based on the numerical solution\nof two coupled Landau-Lifshitz-Gilbert-Slonczewski equations, for the case of\nultra-thin films, i.e. when the N\\'eel temperature of an AFM is substantially\nreduced. We have found two different dynamical modes depending on the strength\nof the Dzyaloshinskii-Moriya interaction (DMI). At low DMI, a large amplitude\nprecession is excited where both the magnetizations of the sublattices are in a\nuniform state and rotate in the same direction. At large enough DMI, the ground\nstate of the AFM becomes non-uniform and the antiferromagnetic dynamics is\ncharacterized by ultrafast domain wall motion.",
        "positive": "Manipulating quantum impurity spins via dynamical modes of nanomagnets: Quantum impurity (QI) spins offer promising information processing and\nsensing applications by harnessing up to room-temperature quantum coherence.\nChallenged by the requirement of designing local coherent drives and improving\nsensitivity to various signals for such applications, the search of hybrid\nsystems coupling QI spins with matter excitations have garnered significant\nrecent interest. We propose and theoretically study a hybrid system that\ncouples spin-1 QI with the dynamical excitations of nanomagnets, which are\ncontrolled by mechanisms uncovered in classical spintronics. We show that in\nsuch systems the QI-spin decoherence, due to coupling to thermally excited\nmodes of the nanomagnet, can be designed across a wide range by exploiting the\ncontrol over nanomagnet's mode ellipticity and the chiral nature of the\ncoupling between the QI spin and nanomagnet. On the other hand, when activated\nelectrically via voltage-induced torques, we demonstrate that QI spins can be\ndriven coherently with large quality factors at room temperature by leveraging\ninherent non-linear precessional modes of the nanomagnet. Our results provide\ntheoretical guidance for enabling unique quantum spintronic functionalities,\nsuch as local coherent driving of QI spins up to ambient conditions, and the\ndesign of nanomagnet-enhanced QI-based hybrid sensors."
    },
    {
        "anchor": "High-Efficiency Van Der Waals heterostructure Thermionic Device With\n  Graphene Electrodes: In this paper, we propose van del Waals heterostructure-based thermionic\ndevices for the applications in cooling and power generation in the temperature\nrange of 300 to 400 K. By using two-dimensional materials of low cross-plane\nthermal conductivity as the barrier materials and graphene as electrodes, our\ncalculation demonstrates that our proposed device will have a higher efficiency\nas compared to other methods such as thermoelectric device and the traditional\nthermionic devices. By using the parameters within the current technology, we\npredict a cooling capability at more than 50$\\%$ of the Carnot efficiency, and\na 10 to 20 $\\%$ efficiency in harvesting the wasted heat at 400 K.",
        "positive": "Itinerant Electron Ferromagnetism in the Quantum Hall Regime: We report on a study of the temperature and Zeeman-coupling-strength\ndependence of the one-particle Green's function of a two-dimensional (2D)\nelectron gas at Landau level filling factor $\\nu =1$ where the ground state is\na strong ferromagnet. Our work places emphasis on the role played by the\nitinerancy of the electrons, which carry the spin magnetization and on\nanalogies between this system and conventional itinerant electron ferromagnets.\nWe discuss the application to this system of the self-consistent Hartree-Fock\napproximation, which is analogous to the band theory description of metallic\nferromagnetism and fails badly at finite temperatures because it does not\naccount for spin-wave excitations. We go beyond this level by evaluating the\none-particle Green's function using a self-energy, which accounts for\nquasiparticle spin-wave interactions. We report results for the temperature\ndependence of the spin magnetization, the nuclear spin relaxation rate, and\n2D-2D tunneling conductances. Our calculations predict a sharp peak in the\ntunneling conductance at large bias voltages with strength proportional to\ntemperature. We compare with experiment, where available, and with predictions\nbased on numerical exact diagonalization and other theoretical approaches."
    },
    {
        "anchor": "Structure and Growth in the Living Tissue and in Carbon Nanotubes: The topological organisation of cells in a model of living tissue (the crypt\nof intestinal epithelium) is identical to the topological organisation of atoms\nin carbon nanotubes. The existing models of growth of these two structures\ncontain identical elements. It is proposed that the growth of carbon nanotubes\ncan depend also on other mechanisms postulated in the crypt model where the\ngrowth in the bottom is transmitted to the cylinder, and, in this case, the\ngrowth of nanotubes should involve the same peculiar lattice transformations as\nthe ones found in the crypt models. The crypt models also suggest a possible\ninitiation of growth in the nanotubes by the loss of carbon atoms. We consider\nthe crystalline structures that can be formed from graphene and the structures\nof the living tissues as one distinct class of structures.",
        "positive": "Transport and optical properties of an electron gas in a Sierpinski\n  carpet: Recent progress in the design and fabrication of artificial two-dimensional\n(2D) materials paves the way for the experimental realization of electron\nsystems moving on plane fractals. In this work, we present the results of\ncomputer simulations for the conductance and optical absorption spectrum of a\n2D electron gas roaming on a Sierpinski carpet, i.e. a plane fractal with\nHausdorff dimension intermediate between one and two. We find that the\nconductance is sensitive to the spatial location of the leads and that it\ndisplays fractal fluctuations whose dimension is compatible with the Hausdorff\ndimension of the sample. Very interestingly, electrons in this fractal display\na broadband optical absorption spectrum, which possesses sharp \"molecular\"\npeaks at low photon energies."
    },
    {
        "anchor": "Electron-hole duality and vortex rings in quantum dots: In a quantum-mechanical system, particle-hole duality implies that instead of\nstudying particles, we can get equivalent information by studying the missing\nparticles, the so-called holes. Using this duality picture for rotating fermion\ncondensates the vortices appear as holes in the Fermi see. Here we predict that\nthe formation of vortices in quantum dots at high magnetic fields causes\noscillations in the energy spectrum which can be experimentally observed using\naccurate tunnelling spectroscopy. We use the duality picture to show that these\noscillations are caused by the localisation of vortices in rings.",
        "positive": "Spin Manipulation and Relaxation in Spin-Orbit Qubits: We derive a generalized form of the Electric Dipole Spin Resonance (EDSR)\nHamiltonian in the presence of the spin-orbit interaction for single spins in\nan elliptic quantum dot (QD) subject to an arbitrary (in both direction and\nmagnitude) applied magnetic field. We predict a nonlinear behavior of the Rabi\nfrequency as a function of the magnetic field for sufficiently large Zeeman\nenergies, and present a microscopic expression for the anisotropic electron\ng-tensor. Similarly, an EDSR Hamiltonian is devised for two spins confined in a\ndouble quantum dot (DQD), where coherent Rabi oscillations between the singlet\nand triplet states are induced by jittering the inter-dot distance at the\nresonance frequency. Finally, we calculate two-electron-spin relaxation rates\ndue to phonon emission, for both in-plane and perpendicular magnetic fields.\nOur results have immediate applications to current EDSR experiments on nanowire\nQDs, g-factor optimization of confined carriers, and spin decay measurements in\nDQD spin-orbit qubits."
    },
    {
        "anchor": "Calculation of the total energy of a diatomic molecule in the first\n  order of perturbation theory taking into account the Pauli principle and\n  plasma oscillations of atomic electrons: In the first order of perturbation theory, the total energy of a diatomic\nmolecule in the ground state is calculated taking into account the Pauli\nprinciple and plasma oscillations of atomic electrons. The Fourier component of\nthe potential energy of interaction of an atom with an atom has the form of a\npolynomial of the fourth degree of the atomic form factor. Numerical\ncalculation is performed for the atomic form factor in the approximation of\nhydrogen-like wave functions, which approximate the solution of the\nHartree-Fock equation for an isolated atom. It is shown that taking into\naccount the plasma oscillations of atomic electrons leads to a self-consistent\nsystem of equations, the numerical solution of which makes it possible to\ndetermine the elastic constant, that is, the value of the second derivative at\nthe minimum of the potential energy of the molecule. The total energy for\nnitrogen and fluorine molecules is calculated.",
        "positive": "Strong and Tunable Spin-Orbit Coupling of One-Dimensional Holes in Ge/Si\n  Core/Shell Nanowires: We investigate the low-temperature magneto-transport properties of individual\nGe/Si core/shell nanowires. Negative magneto-conductance was observed, which is\na signature of one-dimensional weak antilocalization of holes in the presence\nof strong spin-orbit coupling. The temperature and back gate dependences of\nphase coherence length, spin-orbit relaxation time, and background conductance\nwere studied. Specifically, we show the spin-orbit coupling strength can be\nmodulated by more than five folds with an external electric field. These\nresults suggest the Ge/Si nanowire system possesses strong and tunable\nspin-orbit interactions and may serve as a candidate for spintronics\napplications."
    },
    {
        "anchor": "Output spectrum of a detector measuring quantum oscillations: We consider a two-level quantum system (qubit) which is continuously measured\nby a detector and calculate the spectral density of the detector output. In the\nweakly coupled case the spectrum exhibits a moderate peak at the frequency of\nquantum oscillations and a Lorentzian-shape increase of the detector noise at\nlow frequency. With increasing coupling the spectrum transforms into a single\nLorentzian corresponding to random jumps between two states. We prove that the\nBayesian formalism for the selective evolution of the density matrix gives the\nsame spectrum as the conventional master equation approach, despite the\nsignificant difference in interpretation. The effects of the detector\nnonideality and the finite-temperature environment are also discussed.",
        "positive": "Single-molecule time-resolved spectroscopy in a tunable STM nanocavity: The spontaneous fluorescence rates of single-molecule emitters are typically\non the order of nanoseconds. However coupling them with plasmonic\nnanostructures can substantially increase their fluorescence yields. The\nconfinement between the tip and sample of a scanning tunneling microscope\ncreates a tunable nanocavity, an ideal platform for exploring the yields and\nexcitation decay rates of single-molecule emitters depending on the coupling\nstrength to the nanocavity. With this setup we estimate the excitation\nlifetimes from the direct time-resolved measurements of the fluorescence decays\nof phthalocyanine adsorbates, decoupled from the metal substrates by ultrathin\nNaCl layers. It is found that nanosecond-range lifetimes prevail for the\nemitters away from the nanocavity, whereas for the tip approached to a\nmolecule, we find a substantial effect of the nanocavity coupling, which\nreduces the lifetimes to a few picoseconds. An analysis is performed to\ninvestigate the crossover between the far-field and tip-enhanced\nphotoluminescence regimes. This approach overcomes the drawbacks associated\nwith the estimation of lifetimes for single molecules from their respective\nemission linewidths."
    },
    {
        "anchor": "Transport through evanescent waves in ballistic graphene quantum dots: We study the transport through evanescent waves in graphene quantum dots of\ndifferent geometries. The transmission is suppressed when the leads are\nattached to edges of the same majority sublattice. Otherwise, the transmission\ndepends exponentially on the distance between leads in rectangular dots, and as\na power law in circular dots. The transmission through junctions where the\ntransmitted and reflected currents belong to the opposite valley as the\nincoming one depends on details of the lattice structure at distances\ncomparable to the atomic spacing.",
        "positive": "Dispersive magnetometry with a quantum limited SQUID parametric\n  amplifier: There is currently fundamental and technological interest in measuring and\nmanipulating nanoscale magnets, particularly in the quantum coherent regime. To\nobserve the dynamics of such systems one requires a magnetometer with not only\nexceptional sensitivity but also high gain, wide bandwidth and low backaction.\nWe demonstrate a dispersive magnetometer consisting of a two-junction SQUID in\nparallel with an integrated, lumped-element capacitor. Input flux signals are\nencoded as a phase modulation of the microwave drive tone applied to the\nmagnetometer, resulting in a single quadrature voltage signal. For strong drive\npower, the nonlinearity of the resonator results in quantum limited, phase\nsensitive parametric amplification of this signal, which improves flux\nsensitvity at the expense of bandwidth. \\ Depending on the drive parameters,\nthe device performance ranges from an effective flux noise of\n0.29\\textbf{}$\\mu\\Phi_{0}$Hz$^{-\\frac{1}{2}}$ and 20 MHz of signal bandwidth to\na noise of 0.14 $\\mu\\Phi_{0}$Hz$^{-\\frac{1}{2}}$ and a bandwidth of 0.6 MHz.\nThese results are in excellent agreement with our theoretical model."
    },
    {
        "anchor": "Adiabatic continuation of Fractional Chern Insulators to Fractional\n  Quantum Hall States: We show how the phases of interacting particles in topological flat bands,\nknown as fractional Chern insulators, can be adiabatically connected to\nincompressible fractional quantum Hall liquids in the lowest Landau-level of an\nexternally applied magnetic field. Unlike previous evidence suggesting the\nsimilarity of these systems, our approach enables a formal proof of the\nequality of their topological orders, and furthermore this proof robustly\nextends to the thermodynamic limit. We achieve this result using the hybrid\nWannier orbital basis proposed by Qi [Phys. Rev. Lett. 107, 126803 (2011)] in\norder to construct interpolation Hamiltonians that provide continuous\ndeformations between the two models. We illustrate the validity of our approach\nfor the groundstate of bosons in the half filled Chern band of the Haldane\nmodel, showing that it is adiabatically connected to the $\\nu=1/2$ Laughlin\nstate of bosons in the continuum fractional quantum Hall problem.",
        "positive": "Edge state inner products and real-space entanglement spectrum of trial\n  quantum Hall states: We consider the trial wavefunctions for the Fractional Quantum Hall Effect\n(FQHE) that are given by conformal blocks, and construct their associated edge\nexcited states in full generality. The inner products between these edge states\nare computed in the thermodynamic limit, assuming generalized screening (i.e.\nshort-range correlations only) inside the quantum Hall droplet, and using the\nlanguage of boundary conformal field theory (boundary CFT). These inner\nproducts take universal values in this limit: they are equal to the\ncorresponding inner products in the bulk 2d chiral CFT which underlies the\ntrial wavefunction. This is a bulk/edge correspondence; it shows the equality\nbetween equal-time correlators along the edge and the correlators of the bulk\nCFT up to a Wick rotation. This approach is then used to analyze the\nentanglement spectrum (ES) of the ground state obtained with a bipartition\nA\\cupB in real-space. Starting from our universal result for inner products in\nthe thermodynamic limit, we tackle corrections to scaling using standard\nfield-theoretic and renormalization group arguments. We prove that generalized\nscreening implies that the entanglement Hamiltonian H_E = - log {\\rho}_A is\nisospectral to an operator that is local along the cut between A and B. We also\nshow that a similar analysis can be carried out for particle partition. We\ndiscuss the close analogy between the formalism of trial wavefunctions given by\nconformal blocks and Tensor Product States, for which results analogous to ours\nhave appeared recently. Finally, the edge theory and entanglement spectrum of\npx + ipy paired superfluids are treated in a similar fashion in the appendix."
    },
    {
        "anchor": "Approaching Unit Visibility for Control of a Superconducting Qubit with\n  Dispersive Readout: In a Rabi oscillation experiment with a superconducting qubit we show that a\nvisibility in the qubit excited state population of more than 90 % can be\nattained. We perform a dispersive measurement of the qubit state by coupling\nthe qubit non-resonantly to a transmission line resonator and probing the\nresonator transmission spectrum. The measurement process is well characterized\nand quantitatively understood. The qubit coherence time is determined to be\nlarger than 500 ns in a measurement of Ramsey fringes.",
        "positive": "Higher-order contributions and non-perturbative effects in the\n  non-degenerate nonlinear optical absorption of direct-gap semiconductors: The semiconductor Bloch equations for a two-band model including inter- and\nintraband excitation are used to study the nonlinear absorption of single and\nmultiple light pulses by direct-gap semiconductors. For a consistent analysis\nthe contributions to the absorption originating from both the interband\npolarization and the intraband current need to be included. In the Bloch\nequation approach theses contributions as well as different excitation pathways\nin terms of sequences of inter- and intraband excitations can be evaluated\nseparately which allows for a transparent analysis, the identification of the\ndominant terms, and analyzing their dependence on the excitation conditions. In\nthe perturbative regime, we obtain analytical expressions for the multi-photon\nabsorption coefficients for continuous-wave excitation. These results are shown\nto agree well with numerical results for short pulses and/or finite dephasing\nand relaxation times and we confirm the previously predicted strong enhancement\nof two-photon absorption for non-degenerate conditions for pulsed excitation.\nWe discuss the dependencies on the light frequencies, initial band populations,\nand the time delay between the pulses. The frequency dependence of the\ntwo-photon absorption coefficient for non-degenerate excitation is evaluated\nperturbatively in third-order. The higher-order contributions to the optical\nabsorption include three- and four-photon absorption and show a rich frequency\ndependence including negative regions and dispersive lineshapes.\nNon-perturbative solutions of the Bloch equations demonstrate a strongly\nnon-monotonous behavior of the intensity-dependent optical absorption for a\nsingle incident pulse and in a pump-probe set-up."
    },
    {
        "anchor": "Electrical Resistivity Model for Quasi-one-dimensional structures: In this paper electron-impurity scattering coefficient of Bloch waves for one\ndimensional Dirac comb potential is used for calculation of temperature\ndependence of resistivity within kinetic theory. We restrict ourselves by\nscattering on impurities that is also modeled by zero-range potential. The\nstandard averaging is expressed by integral that is evaluated within advanced\nnumerical procedure. The plots on base of the calculations results demonstrate\nstrong variability as function of temperature and impurity strength.",
        "positive": "Probing alloy formation using different excitonic species: The\n  particular case of InGaN: Since the early 1960s, alloys are commonly grouped into two classes,\nfeaturing bound states in the bandgap (I) or additional, non-discrete band\nstates (II). Microscopic material parameters for class I alloys can directly be\nextracted from photoluminescence (PL) spectra, whereas any conclusions drawn\nfor class II alloys usually remain indirect and limited to macroscopic\nassertions. Nonetheless, here, we present a spectroscopic study on exciton\nlocalization in a so-called mixed crystal alloy (class II) that allows us to\naccess microscopic alloy parameters. We study bulk In$_x$Ga$_{1-x}$N epilayers\nat the onset of alloy formation (0 $\\leq$ $x$ $\\leq$ 2.4%) in order to\nunderstand the material's particular robustness to defects. Based on an\nin-depth PL analysis it is demonstrated how different excitonic complexes\n(free, bound, and complex bound excitons) can serve as a probe to monitor the\ndilute limit of class II alloys. From an $x$-dependent linewidth analysis we\nextract the length scales at which excitons become increasingly localized,\nmeaning that they convert from a free to a bound particle upon alloy formation.\nAlready at x = 2.4% the average exciton diffusion length is reduced to 5.7\n$\\pm$ 1.3 nm at a temperature of 12 K, thus, detrimental exciton transfer\nmechanisms towards non-radiative defects are suppressed. In addition, the\nassociated low temperature PL data suggests that a single indium atom does not\nsuffice in order to permanently capture an exciton. Micro-PL spectra even give\naccess to a forthright probing of silicon bound excitons embedded in a\nparticular environment of indium atoms, thanks to the emergence of a hierarchy\nof individual, energetically sharp emission lines (full width at half maximum\n$\\approx$ 300 $\\mu$eV). Consequently, the present study allows us to extract\nfirst microscopic alloy properties formerly only accessible for class I alloys."
    },
    {
        "anchor": "Electronic properties of graphene hexagonal boron nitride moir\u00e9\n  superlattice: We theoretically investigate the electronic structures of moir\\'{e}\nsuperlattices arising in monolayer / bilayer graphene stacked on hexagonal\nboron nitride (hBN) in presence and absence of magnetic field. We develop an\neffective continuum model from a microscopic tight-binding lattice Hamiltonian,\nand calculate the electronic structures of graphene-hBN systems with different\nrotation angles. Using the effective model, we explain the characteristic band\nproperties such as the gap opening at the corners of the superlattice Brillouin\nzone (mini-Dirac point). We also investigate the energy spectrum and quantum\nHall effect of graphene-hBN systems in uniform magnetic field and demonstrate\nthe evolution of the fractal spectrum as a function of the magnetic field. The\nspectrum generally splits in the valley degrees of freedom ($K$ and $K'$) due\nto the lack of the inversion symmetry, and the valley splitting is more\nsignificant in bilayer graphene on hBN than in monolayer graphene on hBN\nbecause of the stronger inversion-symmetry breaking in bilayer.",
        "positive": "Towards hybrid circuit quantum electrodynamics with quantum dots: Cavity quantum electrodynamics allows one to study the interaction between\nlight and matter at the most elementary level. The methods developed in this\nfield have taught us how to probe and manipulate individual quantum systems\nlike atoms and superconducting quantum bits with an exquisite accuracy. There\nis now a strong effort to extend further these methods to other quantum\nsystems, and in particular hybrid quantum dot circuits. This could turn out to\nbe instrumental for a noninvasive study of quantum dot circuits and a\nrealization of scalable spin quantum bit architectures. It could also provide\nan interesting platform for quantum simulation of simple fermion-boson\ncondensed matter systems. In this short review, we discuss the experimental\nstate of the art for hybrid circuit quantum electrodynamics with quantum dots,\nand we present a simple theoretical modeling of experiments."
    },
    {
        "anchor": "Electric field control of magnon-induced magnetization dynamics in\n  multiferroics: We consider theoretically the effect of an inhomogeneous magnetoelectric\ncoupling on the magnon-induced dynamics of a ferromagnet. The magnon-mediated\nmagnetoelectric torque affects both the homogeneous magnetization and\nmagnon-driven domain wall motion. In the domains, we predict a reorientation of\nthe magnetization, controllable by the applied electric field, which is almost\nan order of magnitude larger than that observed in other physical systems via\nthe same mechanism. The applied electric field can also be used to tune the\ndomain wall speed and direction of motion in a linear fashion, producing domain\nwall velocities several times the zero field velocity. These results show that\nmultiferroic systems offer a promising arena to achieve low-dissipation\nmagnetization rotation and domain wall motion by exciting spin-waves.",
        "positive": "Charge noise suppression in capacitively coupled singlet-triplet spin\n  qubits under magnetic field: Charge noise is the main hurdle preventing high-fidelity operation, in\nparticular that of two-qubit gates, of semiconductor-quantum-dot-based spin\nqubits. While certain sweet spots where charge noise is substantially\nsuppressed have been demonstrated in several types of spin qubits, the\nexistence of one for coupled singlet-triplet qubits is unclear. We\ntheoretically demonstrate, using full configuration-interaction calculations,\nthat a range of nearly sweet spots appear in the coupled singlet-triplet qubit\nsystem when a strong enough magnetic field is applied externally. We further\ndemonstrate that ramping to and from the judiciously chosen nearly sweet spot\nusing sequences based on the shortcut to adiabaticity offers maximal gate\nfidelities under charge noise and phonon-induced decoherence. These results\nshould facilitate realization of high-fidelity two-qubit gates in\nsinglet-triplet qubit systems."
    },
    {
        "anchor": "Getting through the nature of silicene: sp2-sp3 two-dimensional silicon\n  nanosheet: By combining experimental techniques with ab-initio density functional theory\ncalculations, we describe the Si/Ag(111) two-dimensional system in terms of a\nsp2-sp3 crystalline form of silicon characterized by a vertically distorted\nhoneycomb lattice. We show that 2D sp2-sp3 Si NSs are qualified by a prevailing\nRaman peak which can be assigned to a graphene-like E2g vibrational mode and\nthat highly distorted superstructures are semiconductive whereas low distorted\nones behave as semimetals.",
        "positive": "Spectroscopy of a single-carrier bilayer graphene quantum dot from\n  time-resolved charge detection: We measured the spectrum of a single-carrier bilayer graphene quantum dot as\na function of both parallel and perpendicular magnetic fields, using a\ntime-resolved charge detection technique that gives access to individual tunnel\nevents. Thanks to our unprecedented energy resolution of 4$\\mu~$eV, we could\ndistinguish all four levels of the dot's first orbital, in particular in the\nrange of magnetic fields where the first and second excited states cross\n($B_\\perp\\lesssim 100~$mT). We thereby experimentally establish, the hitherto\nextrapolated, single-charge carrier spectrum picture and provide a new upper\nbound for the inter-valley mixing, equal to our energy resolution."
    },
    {
        "anchor": "Feedback-tuned noise-resilient gates for encoded spin qubits: Two level quantum mechanical systems like spin 1/2 particles lend themselves\nas a natural qubit implementation. However, encoding a single qubit in several\nspins reduces the resources necessary for qubit control and can protect from\ndecoherence channels. While several varieties of such encoded spin qubits have\nbeen implemented, accurate control remains challenging, and leakage out of the\nsubspace of valid qubit states is a potential issue. Here, we realize\nhigh-fidelity single qubit operations for a qubit encoded in two electron spins\nin GaAs quantum dots by iterative tuning of the all-electrical control pulses.\nUsing randomized benchmarking, we find an average gate fidelity of $\\mathcal{F}\n= (98.5 \\pm 0.1)\\,\\%$ and determine the leakage rate between the computational\nsubspace and other states to $\\mathcal{L} = (0.4\\pm0.1)\\,\\%$. These results\nalso demonstrate that high fidelity gates can be realized even in the presence\nof nuclear spins as in III-V semiconductors.",
        "positive": "Modeling Green's functions measurements with two-tip scanning tunneling\n  microscopy: A double-tip scanning tunneling microscope with nanometer scale tip\nseparation has the ability to access the single electron Green's function in\nreal and momentum space based on second order tunneling processes. Experimental\nrealization of such measurements has been limited to quasi-one-dimensional\nsystems due to the extremely small signal size. Here we propose an alternative\napproach to obtain such information by exploiting the current-current\ncorrelations from the individual tips, and present a theoretical formalism to\ndescribe it. To assess the feasibility of our approach we make a numerical\nestimate for a $\\sim$ 25 nm Pb nanoisland and show that the wavefunction in\nfact extends from tip-to-tip and the signal depends less strongly on increased\ntip separation in the diffusive regime than the one in alternative approaches\nrelying on tip-to-tip conductance."
    },
    {
        "anchor": "Electron wavefunction probing in room-temperature semiconductors: direct\n  observation of Rabi oscillations and self-induced transparency: Quantum coherent light-matter interactions have been at the forefront of\nscientific interest since the fundamental predictions of Einstein and the later\nwork of Rabi. Direct observation of quantum coherent interactions entails\nprobing the electronic wavefunction which requires that the electronic state of\nthe matter does not de-phase during the measurement, a condition that can be\nsatisfied by lengthening the coherence time or by shortening the observation\ntime. The short de-phasing time in semiconductors has dictated that all\ncoherent effects reported to date have been recorded directly only at cryogenic\ntemperatures. Here we report on the first direct electronic wavefunction\nprobing in a room-temperature semiconductor. Employing an ultrafast\ncharacterization scheme we have demonstrated Rabi oscillations and self-induced\ntransparency in an electrically driven, room-temperature semiconductor laser\namplifier, revealing the most intimate details of the light-matter interactions\nseen to date. The ability to employ quantum effects in solid-state media, which\noperate at elevated temperatures, will finally bring true quantum mechanical\nconcepts into the realm of practical devices.",
        "positive": "Hermitian chiral boundary states in non-Hermitian topological insulators: Eigenenergies of a non-Hermitian system without parity-time symmetry are\ncomplex in general. Here, we show that the chiral boundary states of\nhigher-dimensional (two-dimensional and three-dimensional) non-Hermitian\ntopological insulators without parity-time symmetry can be Hermitian with real\neigenenergies under certain conditions. Our approach allows one to construct\nHermitian chiral edge and hinge states from non-Hermitian two-dimensional Chern\ninsulators and three-dimensional second-order topological insulators,\nrespectively. Such Hermitian chiral boundary channels have perfect transmission\ncoefficients (quantized values) and are robust against disorders. Furthermore,\na non-Hermitian topological insulator can undergo the topological Anderson\ninsulator transition from a topological trivial non-Hermitian metal or\ninsulator to a topological Anderson insulator with quantized transmission\ncoefficients at finite disorders."
    },
    {
        "anchor": "Charge-Hall effect driven by spin force: reciprocal of the spin-Hall\n  effect: A new kind of charge-Hall effect is shown. Unlike in the usual Hall effect,\nthe driving force in the longitudinal direction is a spin force, which may\noriginate from the gradient of a Zeeman field or a spin-dependent chemical\npotential. The transverse force is provided by a Berry curvature in a mixed\nposition-momentum space. We can establish an Onsager relation between this\neffect and the spin-Hall effect provided the spin current in the latter is\nmodified by a torque dipole contribution. This remarkable relation leads to new\nways for experimental detection of spin accumulation predicted by the spin Hall\neffect.",
        "positive": "Lamb shift of interactive electron-hole pairs in spherical semiconductor\n  quantum dots: The ground state Lamb shift of a semiconductor spherical Quantum Dot is\ncomputed in the effective mass approximation. It appears to be significant\nenough to be detectable for a wide range of small Quantum Dots synthesized in\nsemiconductors. A possible way to bserve it, via the Casimir effect, is\nsuggested."
    },
    {
        "anchor": "Charge-sensing of a Ge/Si core/shell nanowire double quantum dot using a\n  high-impedance superconducting resonator: Spin qubits in germanium are a promising contender for scalable quantum\ncomputers. Reading out of the spin and charge configuration of quantum dots\nformed in Ge/Si core/shell nanowires is typically performed by measuring the\ncurrent through the nanowire. Here, we demonstrate a more versatile approach on\ninvestigating the charge configuration of these quantum dots. We employ a\nhigh-impedance, magnetic-field resilient superconducting resonator based on\nNbTiN and couple it to a double quantum dot in a Ge/Si nanowire. This allows us\nto dispersively detect charging effects, even in the regime where the nanowire\nis fully pinched off and no direct current is present. Furthermore, by\nincreasing the electro-chemical potential far beyond the nanowire pinch-off, we\nobserve indications for depleting the last hole in the quantum dot by using the\nsecond quantum dot as a charge sensor. This work opens the door for dispersive\nreadout and future spin-photon coupling in this system.",
        "positive": "Direct Observation of Ferromagnetic State in Gold Nanorods Probed using\n  Electron Spin Resonance Spectroscopy: X-band electron spin resonance (ESR) spectroscopy has been performed for gold\nnanorods (AuNRs) of four different sizes covered with a diamagnetic stabilizing\ncomponent, cetyltrimethylammmonium bromide. The ESR spectra show ferromagnetic\nfeatures such as hysteresis and resonance field shift, depending on the size of\nthe AuNRs. In addition, the ferromagnetic transition is indicated by an abrupt\nchange in the spectra of the two smallest AuNRs studied. A large g-value in the\nparamagnetic region suggests that the ferromagnetism in the AuNRs originates\nfrom strong spin-orbit interaction."
    },
    {
        "anchor": "Quantum hybridization negative differential resistance from non-toxic\n  halide perovskite nanowire heterojunctions and its strain control: While low-dimensional organometal halide perovskites are expected to open up\nnew opportunities for a diverse range of device applications, like in their\nbulk counterparts, the toxicity of Pb-based halide perovskite materials is a\nsignificant concern that hinders their practical use. We recently predicted\nthat lead triiodide (PbI$_3$) columns de-rived from trimethylsulfonium (TMS)\nlead triiodide (CH$_3$)$_3$SPbI$_3$ (TMSPbI$_3$) by stripping off TMS ligands\nshould be semimetallic, and additionally ultrahigh negative differential\nresistance (NDR) can arise from the heterojunction composed of a TMSPbI$_3$\nchannel sandwiched by PbI$_3$ electrodes. Herein, we computationally explore\nwhether similar material and device characteristics can be obtained from other\none-dimensional halide perovskites based on non-Pb metal elements, and in doing\nso deepen the understanding of their mechanistic origins. First, scanning\nthrough several candidate metal halide inorganic frameworks as well as their\nparental form halide perovskites, we find that the germanium triiodide\n(GeI$_3$) column also assumes a semimetallic character by avoiding the Peierls\ndistortion. Next, adopting the bundled nanowire GeI$_3$-TMSGeI$_3$-GeI$_3$\njunction configuration, we obtain a drastically high peak current density and\nultrahigh NDR at room temperature. Furthermore, the robustness and\ncontrollability of NDR signals under strain are revealed, establishing its\npotential for flexible electronics applications. It will be emphasized that,\ndespite the performance metrics notably enhanced over those from the\nPbI$_3$-TMSPbI$_3$-PbI$_3$ case, these device characteristics still arise from\nthe identical quantum hybridization NDR mechanism.",
        "positive": "Optical absorption of angulon in metal halide perovskites: We theoretically study the optical absorption of an angulon in the metal\nhalide perovskites (MHP) based on the improved Devreese-Huybrechts-Lemmens\nmodel, where the formation of quasiparticle angulon states originates from the\norganic cation rotating in the inorganic octahedral cage of MHP. We find that\nthe resonance optical absorption peaks are appeared when the energy of incident\nphoton matches the quantum levels of angulon. Moreover, the intensity of\nabsorption depends on the quantum states of phonon angular momentum. These\ntheoretical results provide significant insight to study the redistribution of\nangular momenta for the rotational molecules immersed into the many-body\nenvironment."
    },
    {
        "anchor": "Bulk-boundary correspondence for non-Hermitian Hamiltonians via Green\n  functions: Genuinely non-Hermitian topological phases can be realized in open systems\nwith sufficiently strong gain and loss; in such phases, the Hamiltonian cannot\nbe deformed into a gapped Hermitian Hamiltonian without energy bands touching\neach other. Comparing Green functions for periodic and open boundary conditions\nwe find that, in general, there is no correspondence between topological\ninvariants computed for periodic boundary conditions, and boundary eigenstates\nobserved for open boundary conditions. Instead, we find that the non-Hermitian\nwinding number in one dimension signals a topological phase transition in the\nbulk: It implies spatial growth of the bulk Green function.",
        "positive": "Critical size limits for collinear and spin spiral magnetism in\n  CoCr$_2$O$_4$: The multiferroic behavior of CoCr$_2$O$_4$ results from the appearance of\nconical spin-spiral magnetic ordering, which induces electric polarization. The\nmagnetic ground state has a complex size dependent behavior, which collapses\nwhen reaching a critical particle size. Here, the magnetic phase stability of\nCoCr$_2$O$_4$ in the size range of 3.6 - 14.0 nm is presented in detail using\nthe combination of neutron diffraction with XYZ polarization analysis and\nmacroscopic magnetization measurements. We establish critical coherent domain\nsizes for the formation of the spin spiral and ferrimagnetic structure and\nreveal the evolution of the incommensurate spin spiral vector with particle\nsize. We further confirm the presence of ferroelectric polarization in the spin\nspiral phase for nanocrystalline CoCr$_2$O$_4$."
    },
    {
        "anchor": "Unexpected phonon-transport properties of stanene among 2D group-IV\n  materials from \\textit{ab initio}: It has been argued that stanene has lowest lattice thermal conductivity among\n2D group-IV materials because of largest atomic mass, weakest interatomic\nbonding, and enhanced ZA phonon scattering due to the breaking of an\nout-of-plane symmetry selection rule. However, we show that although the\nlattice thermal conductivity $\\kappa$ for graphene, silicene and germanene\ndecreases monotonically with decreasing Debye temperature, unexpected higher\n$\\kappa$ is observed in stanene. By enforcing all the invariance conditions in\n2D materials and including Ge $3d$ and Sn $4d$ electrons as valence electrons\nfor germanene and stanene respectively, the lattice dynamics in these materials\nare accurately described. A large acoustic-optical gap and the bunching of the\nacoustic phonon branches significantly reduce phonon scattering in stanene,\nleading to higher thermal conductivity than germanene. The vibrational origin\nof the acoustic-optical gap can be attributed to the buckled structure.\nInterestingly, a buckled system has two competing influences on phonon\ntransport: the breaking of the symmetry selection rule leads to reduced thermal\nconductivity, and the enlarging of the acoustic-optical gap results in enhanced\nthermal conductivity. The size dependence of thermal conductivity is\ninvestigated as well. In nanoribbons, the $\\kappa$ of silicene, germanene and\nstanene is much less sensitive to size effect due to their short intrinsic\nphonon mean free paths. This work sheds light on the nature of phonon transport\nin buckled 2D materials.",
        "positive": "Registry-dependent potential energy and lattice corrugation of twisted\n  bilayer graphene from quantum Monte Carlo: An uncertainty in studying twisted bilayer graphene (TBG) is the minimum\nenergy geometry, which strongly affects the electronic structure. The minimum\nenergy geometry is determined by the potential energy surface, which is\ndominated by van der Waals (vdW) interactions. In this work, large-scale\ndiffusion quantum Monte Carlo (QMC) simulations are performed to evaluate the\nenergy of bilayer graphene at various interlayer distances for four stacking\nregistries. An accurate registry-dependent potential is fit to the QMC data and\nis used to describe interlayer interactions in the geometry of near-magic-angle\nTBG. The band structure for the optimized geometry is evaluated using the\naccurate local-environment tight-binding model. We find that compared to QMC,\nDFT-based vdW interactions can result in errors in the corrugation magnitude by\na factor of 2 or more near the magic angle. The error in corrugation then\npropagates to the flat bands in twisted bilayer graphene, where the error in\ncorrugation can affect the bandwidth by about 30\\% and can change the nature\nand degeneracy of the flat bands."
    },
    {
        "anchor": "Corner states of topological fullerenes: The unusual electronic properties of the quantum spin Hall or Chern insulator\nbecome manifest in the form of robust edge states when samples with boundaries\nare studied. In this work, we ask if and how the topologically non-trivial\nelectronic structure of these two-dimensional systems can be passed on to their\nzero-dimensional relatives, namely fullerenes or other closed-cage molecules.\nTo address this question, we study Haldane's honeycomb lattice model on\npolyhedral nano-surfaces. We find that for sufficiently large surfaces\ncharacteristic corner states appear for parameters for which the planar model\ndisplays a quantized Hall effect. In the electronic structure, these corner\nstates show up as in-gap modes which are well separated from the\nquasi-continuum of states. We discuss the role of finite size effects and how\nthe coupling between the corner states lifts the degeneracy in a characteristic\nway determined by the combined Berry phases which leads to an effective\nmagnetic monopole of charge 2 at the center of the nano-surface. Experimental\nimplications for fullerenes in the large spin-orbit regime are also pointed\nout.",
        "positive": "Non-equilibrium diffusion of dark excitons in atomically thin\n  semiconductors: Atomically thin semiconductors provide an excellent platform to study\nintriguing many-particle physics of tightly-bound excitons. In particular, the\nproperties of tungsten-based transition metal dichalcogenides are determined by\na complex manifold of bright and dark exciton states. While dark excitons are\nknown to dominate the relaxation dynamics and low-temperature\nphotoluminescence, their impact on the spatial propagation of excitons has\nremained elusive. In our joint theory-experiment study, we address this\nintriguing regime of dark state transport by resolving the spatio-temporal\nexciton dynamics in hBN-encapsulated WSe$_2$ monolayers after resonant\nexcitation. We find clear evidence of an unconventional, time-dependent\ndiffusion during the first tens of picoseconds, exhibiting strong deviation\nfrom the steady-state propagation. Dark exciton states are initially populated\nby phonon emission from the bright states, resulting in creation of hot\nexcitons whose rapid expansion leads to a transient increase of the diffusion\ncoefficient by more than one order of magnitude. These findings are relevant\nfor both fundamental understanding of the spatio-temporal exciton dynamics in\natomically thin materials as well as their technological application by\nenabling rapid diffusion."
    },
    {
        "anchor": "Effect of initial correlations on short-time decoherence: We study the effect of initial correlations on the short-time decoherence of\na particle linearly coupled to a bath of harmonic oscillators. We analytically\nevaluate the attenuation coefficient of a Schroedinger cat state both for a\nfree and a harmonically bound particle, with and without initial thermal\ncorrelations between the particle and the bath. While short-time decoherence\nappears to be independent of the system in the absence of initial correlations,\nwe find on the contrary that, for initial thermal correlations, decoherence\nbecomes system dependent even for times much shorter than the characteristic\ntime of the system. The temperature behavior of this system dependence is\ndiscussed.",
        "positive": "Non-adiabatic effect on Laughlin's argument of the quantum Hall effect: We have numerically studied a non-adiabatic charge transport in the quantum\nHall system pumped by a magnetic flux, as one of the simplest theoretical\nrealizations of non-adiabatic Thouless pumping. In the adiabatic limit, a\npumped charge is quantized, known as Laughlin's argument in a cylindrical\nlattice. In a uniform electric field, we obtained a formula connecting\nquantized pumping in the adiabatic limit and no-pumping in the sudden limit.\nThe intermediate region between the two limits is determined by the Landau gap.\nA randomness or impurity effect is also discussed."
    },
    {
        "anchor": "Model spin-orbit coupling Hamiltonians for graphene systems: We present a detailed theoretical study of effective spin-orbit coupling\n(SOC) Hamiltonians for graphene based systems, covering global effects such as\nproximity to substrates and local SOC effects resulting, for example, from\ndilute adsorbate functionalization. Our approach combines group theory and\ntight-binding descriptions. We consider structures with global point group\nsymmetries $D_{6h}$, $D_{3d}$, $D_{3h}$, $C_{6v}$, and $C_{3v}$ that represent,\nfor example, pristine graphene, graphene mini-ripple, planar boron-nitride,\ngraphene on a substrate and free standing graphone, respectively. The presence\nof certain spin-orbit coupling parameters is correlated with the absence of the\nspecific point group symmetries. Especially in the case of $C_{6v}$---graphene\non a substrate, or transverse electric field---we point out the presence of a\nthird SOC parameter, besides the conventional intrinsic and Rashba\ncontributions, thus far neglected in literature. For all global structures we\nprovide effective SOC Hamiltonians both in the local atomic and Bloch forms.\nDilute adsorbate coverage results in the local point group symmetries $C_{6v}$,\n$C_{3v}$, and $C_{2v}$ which represent the stable adsorption at hollow, top and\nbridge positions, respectively. For each configuration we provide effective SOC\nHamiltonians in the atomic orbital basis that respect local symmetries. In\naddition to giving specific analytic expressions for model SOC Hamiltonians, we\nalso present general (no-go) arguments about the absence of certain SOC terms.",
        "positive": "Anomalous Electromagnetic Induction Engendered by Singular Gauge\n  Transformation: The Berry curvature, resembling the magnetic field in reciprocal space,\noffers a captivating avenue for exploring unique electromagnetic phenomena\ndevoid of real-space analogs. Here, we investigate the emergent electromagnetic\ninduction by solenoidal Berry curvature with its field lines forming loops,\nlinks, and knots. In stark contrast to Faraday's law, which dictates that\nalternating magnetic fields yield alternating electric fields with a net zero\naverage, the alternating Berry curvature can engender directional\nelectromagnetic induction. Such an effect is attributed to the presence of\nsingularities in the Berry curvature, accompanied by a $2\\pi$ jump in the Berry\nflux. Notably, this jump does not trigger a diamagnetic impulse, due to the\ngauge invariance of the Berry phase modulo $2\\pi$. Consequently, the induced\nelectric field maintains finite values under time averaging, manifesting itself\nas a directional pumping current. Our research sheds light on an anomalous\nelectromagnetic induction effect directly arising from the singular gauge\ntransformation, thereby expanding our comprehension of exotic electromagnetic\nphenomena."
    },
    {
        "anchor": "Transient dynamics of double quantum dots coupled to two reservoirs: We study the time-dependent properties of double quantum dots coupled to two\nreservoirs using the nonequilibrium Green function method. For an arbitrary\ntime-dependent bias, we derive an expression for the time-dependent electron\ndensity of a dot and several currents, including the current between the dots\nin the wide-band-limit approximation. For the special case of a constant bias,\nwe calculate the electron density and the currents numerically. As a result, we\nfind that these quantities oscillate and that the number of crests in a single\nperiod of the current from a dot changes with the bias voltage. We also obtain\nan analytical expression for the relaxation time, which expresses how fast the\nsystem converges to its steady state. From the expression, we find that the\nrelaxation time becomes constant when the coupling strength between the dots is\nsufficiently large in comparison with the difference of coupling strength\nbetween the dots and the reservoirs.",
        "positive": "Current direction induced rectification effect on (integer) quantized\n  Hall plateaus: Current polarization induced rectification of the quantized Hall plateaus\n(QHPs) is studied within a Hartree type mean field approximation for\nasymmetrically depleted samples. We first investigate the existence of the\ncurrent carrying incompressible strips (ISs), by solving the self-consistent\nequations, and their influence on magneto-transport (MT) properties. Next, the\nwidths of the ISs are examined in terms of the steepness of the confining\npotential profile considering gate defined Hall bars. The corresponding MT\ncoefficients are calculated using a local Ohm's law for a large fixed current\nand are compared for symmetric and asymmetric depleted samples. We predict\nthat, the extend of the QHPs strongly depend on the current polarization, in\nthe out of linear response regime, when considering asymmetrically depleted\nsamples. Our results, concerning the extend of the QHPs depending on the\ncurrent polarization are in contrast to the ones of the conventional theories\nof the integer quantized Hall effect (IQHE). We propose certain experimental\nconditions to test our theoretical predictions at high mobility, narrow\nsamples."
    },
    {
        "anchor": "Magnetic and Optical Response of Chiral Fermions: Dirac and Weyl materials possess chiral fermions, which are characterized by\nnontrivial topology and large Berry curvature. Chiral fermions have nontrivial\ninteractions with magnetic fields and light. In this work, we propose three\ndifferent mechanisms for magnetic photocurrents caused by chiral fermions, with\ndifferent requirements on the symmetry group of the crystal. We also study\nquantum oscillations of the anomalous current in the presence of a magnetic\nfield, showing it has a different phase from the Ohmic current. We formulate a\nmechanism for THz emission observed in TaAs in response to ultrafast pulses. We\npropose a strain-induced anomalous current. We also show that an external\nmagnetic field can create a difference between left and right handed fermions,\nwhich can be controlled by changing the field.",
        "positive": "Theory of the topological Anderson insulator: We present an effective medium theory that explains the disorder-induced\ntransition into a phase of quantized conductance, discovered in computer\nsimulations of HgTe quantum wells. It is the combination of a random potential\nand quadratic corrections proportional to p^2 sigma_z to the Dirac Hamiltonian\nthat can drive an ordinary band insulator into a topological insulator (having\nan inverted band gap). We calculate the location of the phase boundary at weak\ndisorder and show that it corresponds to the crossing of a band edge rather\nthan a mobility edge. Our mechanism for the formation of a topological Anderson\ninsulator is generic, and would apply as well to three-dimensional\nsemiconductors with strong spin-orbit coupling."
    },
    {
        "anchor": "Effect of Exchange Interaction on Spin Dephasing in a Double Quantum Dot: We measure singlet-triplet dephasing in a two-electron double quantum dot in\nthe presence of an exchange interaction which can be electrically tuned from\nmuch smaller to much larger than the hyperfine energy. Saturation of dephasing\nand damped oscillations of the spin correlator as a function of time are\nobserved when the two interaction strengths are comparable. Both features of\nthe data are compared with predictions from a quasistatic model of the\nhyperfine field.",
        "positive": "The Emission Directionality of Electronic Intraband Transitions in\n  Stacked Quantum Dots: We investigate the emission directionality of electronic intraband\n(intersubband) transitions in stacked coupled quantum dots. Using a\nwell-established eight-band $k \\cdot p$ method, we demonstrate that the minor\ncontributions from the valence band mixing into the conduction band govern the\npolarization and emission directionality of electronic $p$-to-$s$-type\nintraband transitions. Despite that the contribution from the central-cell part\nto the momentum matrix element is dominant, we find, the contribution from the\nmatrix elements among the envelope functions cannot be neglected. With the help\nof an artificial cuboidal quantum dot, we show that the vertical emission from\nintraband transitions can be tuned via the emitter's vertical aspect ratio.\nSubsequently, we show that these results can be transferred to more realistic\ngeometries of quantum dots and quantum dot stacks and demonstrate that the\nvertical emission can be enhanced from $23$ % to $46$ % by increasing the\nemitter's vertical aspect ratio to the isotropic case with a vertical aspect\nratio of 1.0. Therefore, a stacking of a few quantum dots ($\\sim$4 for the\ninvestigated structures) is already sufficient to improve the vertical\nradiation significantly. Additionally, we discuss the impact of the number of\nstacked QDs as well as the effect of the interdot coupling strength on the\nradiation properties."
    },
    {
        "anchor": "AFM Dissipation Topography of Soliton Superstructures in Adsorbed\n  Overlayers: In the atomic force microscope, the nanoscale force topography of even\ncomplex surface superstructures is extracted by the changing vibration\nfrequency of a scanning tip. An alternative dissipation topography with similar\nor even better contrast has been demonstrated recently by mapping the\n(x,y)-dependent tip damping but the detailed damping mechanism is still\nunknown. Here we identify two different tip dissipation mechanisms: local\nmechanical softness and hysteresis. Motivated by recent data, we describe both\nof them in a onedimensional model of Moire' superstructures of incommensurate\noverlayers. Local softness at \"soliton\" defects yields a dissipation contrast\nthat can be much larger than the corresponding density or corrugation contrast.\nAt realistically low vibration frequencies, however, a much stronger and more\neffective dissipation is caused by the tip-induced nonlinear jumping of the\nsoliton, naturally developing bistability and hysteresis. Signatures of this\nmechanism are proposed for experimental identification.",
        "positive": "Gate-controlled skyrmion and domain wall chirality: Magnetic skyrmions are localized chiral spin textures, which offer great\npromise to store and process information at the nanoscale. In the presence of\nasymmetric exchange interactions, their chirality, which governs their\ndynamics, is generally considered as an intrinsic parameter set during the\nsample deposition. In this work, we experimentally demonstrate that a gate\nvoltage can control this key parameter. We probe the chirality of skyrmions and\nchiral domain walls by observing the direction of their current-induced motion\nand show that a gate voltage can reverse it. This local and dynamical reversal\nof the chirality is due to a sign inversion of the interfacial\nDzyaloshinskii-Moriya interaction that we attribute to ionic migration of\noxygen under gate voltage. Micromagnetic simulations show that the chirality\nreversal is a continuous transformation, in which the skyrmion is conserved.\nThis control of chirality with 2 - 3 V gate voltage can be used for\nskyrmion-based logic devices, yielding new functionalities."
    },
    {
        "anchor": "Zeeman splitting in ballistic hole quantum wires: We have studied the Zeeman splitting in ballistic hole quantum wires formed\nin a (311)A quantum well by surface gate confinement. Transport measurements\nclearly show lifting of the spin degeneracy and crossings of the subbands when\nan in-plane magnetic field B is applied parallel to the wire. When B is\noriented perpendicular to the wire, no spin-splitting is discernible up to B =\n8.8 T. The observed large Zeeman splitting anisotropy in our hole quantum wires\ndemonstrates the importance of quantum-confinement for spin-splitting in\nnanostructures with strong spin-orbit coupling.",
        "positive": "Scalability of Atomic-Thin-Body (ATB) Transistors Based on Graphene\n  Nanoribbons: A general solution for the electrostatic potential in an atomic-thin-body\n(ATB) field-effect transistor geometry is presented. The effective\nelectrostatic scaling length, {\\lambda}eff, is extracted from the analytical\nmodel, which cannot be approximated by the lowest order eigenmode as\ntraditionally done in SOI-MOSFETs. An empirical equation for the scaling length\nthat depends on the geometry parameters is proposed. It is shown that even for\na thick SiO2 back oxide {\\lambda}eff can be improved efficiently by thinner top\noxide thickness, and to some extent, with high-k dielectrics. The model is then\napplied to self-consistent simulation of graphene nanoribbon (GNR)\nSchottky-barrier field-effect transistors (SB-FETs) at the ballistic limit. In\nthe case of GNR SB-FETs, for large {\\lambda}eff, the scaling is limited by the\nconventional electrostatic short channel effects (SCEs). On the other hand, for\nsmall {\\lambda}eff, the scaling is limited by direct source-to-drain tunneling.\nA subthreshold swing below 100mV/dec is still possible with a sub-10nm gate\nlength in GNR SB-FETs."
    },
    {
        "anchor": "Tuning of Fermi Contour Anisotropy in GaAs (001) 2D Holes via Strain: We demonstrate tuning of the Fermi contour anisotropy of two-dimensional (2D)\nholes in a symmetric GaAs (001) quantum well via the application of in-plane\nstrain. The ballistic transport of high-mobility hole carriers allows us to\nmeasure the Fermi wavevector of 2D holes via commensurability oscillations as a\nfunction of strain. Our results show that a small amount of in-plane strain, on\nthe order of $10^{-4}$, can induce significant Fermi wavevector anisotropy as\nlarge as 3.3, equivalent to a mass anisotropy of 11 in a parabolic band. Our\nmethod to tune the anisotropy \\textit{in situ} provides a platform to study the\nrole of anisotropy on phenomena such as the fractional quantum Hall effect and\ncomposite fermions in interacting 2D systems.",
        "positive": "Inhomogeneous dynamic nuclear polarization and suppression of\n  electron-polarization decay in a quantum dot: We investigate the dynamic nuclear polarization process by frequently\ninjecting polarized electron spins into a quantum dot. Due to the suppression\nof the direct dipolar and indirect electron-mediated nuclear spin interactions,\nby the frequently injected electron spins, the analytical predictions under the\nindependent spin approximation agree well with quantum numerical simulations.\nOur results show that the acquired nuclear polarization is highly\ninhomogeneous, proportional to the square of the local electron-nuclear\nhyperfine interaction constant, if the injection frequency is high. Utilizing\nthe inhomogeneously polarized nuclear spins as an initial state, we further\nshow that the electron-polarization decay time can be extended 100 times even\nat a relatively low nuclear polarization (<20%), without much suppression of\nthe fluctuation of the Overhauser field. Our results lay the foundation for\nfuture investigations of the effect of DNP in more complex spin systems, such\nas double quantum dots and nitrogen vacancy centers in diamonds."
    },
    {
        "anchor": "Signatures of topological phase transitions in Josephson current-phase\n  discontinuities: Topological superconductors differ from topologically trivial ones for the\npresence of topologically protected zero-energy modes. To date, experimental\nevidence of topological superconductivity in nanostructures has been mainly\nobtained by measuring the zero-bias conductance peak via tunneling\nspectroscopy. Here, we propose an alternative and complementary experimental\nrecipe to detect topological phase transitions in these systems. We show in\nfact that, for a finite-sized system with broken time-reversal symmetry,\ndiscontinuities in the Josephson current-phase relation correspond to the\npresence of zero-energy modes and to a change in the fermion parity of the\ngroundstate. Such discontinuities can be experimentally revealed by a\ncharacteristic temperature dependence of the current, and can be related to a\nfinite anomalous current at zero phase in systems with broken phase-inversion\nsymmetry.",
        "positive": "A simple test for ideal memristors: An ideal memristor is defined as a resistor with memory that, when subject to\na time-dependent current, $I(t)$, its resistance $R_M(q)$ depends {\\it only} on\nthe charge $q$ that has flowed through it, so that its voltage response is\n$V(t)=R_M(q)I(t)$. It has been argued that a clear fingerprint of these ideal\nmemristors is a pinched hysteresis loop in their I-V curves. However, a pinched\nI-V hysteresis loop is not a definitive test of whether a resistor with memory\nis truly an ideal memristor because such a property is shared also by other\nresistors whose memory depends on additional internal state variables, other\nthan the charge. Here, we introduce a very simple and {\\it unambiguous} test\nthat can be utilized to check experimentally if a resistor with memory is\nindeed an ideal memristor. Our test is based on the duality property of a\ncapacitor-memristor circuit whereby, for any initial resistance states of the\nmemristor and any form of the applied voltage, the final state of an ideal\nmemristor must be identical to its initial state, if the capacitor charge\nfinally returns to its initial value. In actual experiments, a sufficiently\nwide range of voltage amplitudes and initial states are enough to perform the\ntest. The proposed test can help resolve some long-standing controversies still\nexisting in the literature about whether an ideal memristor does actually exist\nor it is a purely mathematical concept."
    },
    {
        "anchor": "The interfacial spin modulation of graphene on Fe(111): When Fe, which is a typical ferromagnet using d- or f-orbital states, is\ncombined with 2D materials such as graphene, it offers many opportunities for\nspintronics. The origin of 2D magnetism is from magnetic insulating behaviors,\nwhich could result in magnetic excitations and also proximity effects. However,\nthe phenomena were only observed at extremely low temperatures. Fe and graphene\ninterfaces could control spin structures in which they show a unique atomic\nspin modulation and magnetic coupling through the interface. Another reason for\ncovering graphene on Fe is to prevent oxidation under ambient conditions. We\ninvestigated the engineering of spin configurations by growing monolayer\ngraphene on an Fe(111) single crystal surface and observed the presence of\nsharply branched, 3D tree-like domain structures. Magnetization by a sweeping\nmagnetic field (m-H) revealed that the interface showed canted magnetization in\nthe in-plane (IP) orientation. Moreover, graphene could completely prevent the\noxidation of the Fe surface. The results indicate possible control of the spin\nstructures at the atomic scale and the interface phenomena in the 2D structure.\nThe study introduces a new approach for room temperature 2D magnetism.",
        "positive": "Asymptotic behavior of the conductance in disordered wires with\n  perfectly conducting channels: We study the conductance of disordered wires with unitary symmetry focusing\non the case in which $m$ perfectly conducting channels are present due to the\nchannel-number imbalance between two-propagating directions. Using the exact\nsolution of the Dorokhov-Mello-Pereyra-Kumar (DMPK) equation for transmission\neigenvalues, we obtain the average and second moment of the conductance in the\nlong-wire regime. For comparison, we employ the three-edge Chalker-Coddington\nmodel as the simplest example of channel-number-imbalanced systems with $m =\n1$, and obtain the average and second moment of the conductance by using a\nsupersymmetry approach. We show that the result for the Chalker-Coddington\nmodel is identical to that obtained from the DMPK equation."
    },
    {
        "anchor": "Universal pinning energy barrier for driven domain walls in thin\n  ferromagnetic films: We report a comparative study of magnetic field driven domain wall motion in\nthin films made of different magnetic materials for a wide range of field and\ntemperature. The full thermally activated creep motion, observed below the\ndepinning threshold, is shown to be described by a unique universal energy\nbarrier function. Our findings should be relevant for other systems whose\ndynamics can be modeled by elastic interfaces moving on disordered energy\nlandscapes.",
        "positive": "High-frequency rectification in graphene lateral p-n junctions: We observe a dc electric current in response to terahertz radiation in\nlateral inter-digitated double-comb graphene p-n junctions. The junctions were\nfabricated by selective ultraviolet irradiation inducing p-type doping in\nintrinsic n-type epitaxial monolayer graphene. The photocurrent exhibits a\nstrong polarization dependence and is explained by electric rectification in\np-n junctions."
    },
    {
        "anchor": "Ground State Properties of Quantum Skyrmions described by Neural Network\n  Quantum States: We investigate the ground state properties of quantum skyrmions in a\nferromagnet using variational Monte Carlo with the neural network quantum state\nas variational ansatz. We study the ground states of a two-dimensional quantum\nHeisenberg model in the presence of the Dzyaloshinskii-Moriya interaction\n(DMI). We show that the ground state accommodates a quantum skyrmion for a\nlarge range of parameters, especially at large DMI. The spins in these quantum\nskyrmions are weakly entangled, and the entanglement increases with decreasing\nDMI. We also find that the central spin is completely disentangled from the\nrest of the lattice, establishing a non-destructive way of detecting this type\nof skyrmion by local magnetization measurements. While neural networks are well\nsuited to detect weakly entangled skyrmions with large DMI, they struggle to\ndescribe skyrmions in the small DMI regime due to nearly degenerate ground\nstates and strong entanglement. In this paper, we propose a method to identify\nthis regime and a technique to alleviate the problem. Finally, we analyze the\nworkings of the neural network and explore its limits by pruning. Our work\nshows that neural network quantum states can be efficiently used to describe\nthe quantum magnetism of large systems exceeding the size manageable in exact\ndiagonalization by far.",
        "positive": "Iterative approach to arbitrary nonlinear optical response functions of\n  graphene: Two-dimensional materials constitute an exciting platform for nonlinear\noptics with large nonlinearities that are tunable by gating. Hence,\ngate-tunable harmonic generation and intensity-dependent refraction have been\nobserved in e.g. graphene and transition-metal dichalcogenides, whose\nelectronic structures are accurately modelled by the (massive) Dirac equation.\nWe exploit on the simplicity of this model and demonstrate here that arbitrary\nnonlinear response functions follow from a simple iterative approach. The power\nof this approach is illustrated by analytical expressions for harmonic\ngeneration and intensity-dependent refraction, both computed up to ninth order\nin the pump field. Moreover, the results allow for arbitrary band gaps and\ngating potentials. As illustrative applications, we consider (i)\ngate-dependence of third- and fifth-harmonic generation in gapped and gapless\ngraphene, (ii) intensity-dependent refractive index of graphene up to ninth\norder, and (iii) intensity-dependence of high-harmonic generation."
    },
    {
        "anchor": "Imaging isodensity contours of molecular states with STM: We present an improved way for imaging the local density of states with a\nscanning tunneling microscope, which consists in mapping the surface topography\nwhile keeping the differential conductance (d$I$/d$V$) constant. When\narchetypical C$_{60}$ molecules on Cu(111) are imaged with this method, these\nso-called iso-d$I$/d$V$ maps are in excellent agreement with theoretical\nsimulations of the isodensity contours of the molecular orbitals. A direct\nvisualization and unambiguous identification of superatomic C$_{60}$ orbitals\nand their hybridization is then possible.",
        "positive": "Binding energies of trions and biexcitons in two-dimensional\n  semiconductors from diffusion quantum Monte Carlo calculations: Excitonic effects play a particularly important role in the optoelectronic\nbehavior of two-dimensional (2D) semiconductors. To facilitate the\ninterpretation of experimental photoabsorption and photoluminescence spectra we\nprovide statistically exact diffusion quantum Monte Carlo binding-energy data\nfor Mott-Wannier models of excitons, trions, and biexcitons in 2D\nsemiconductors. We also provide contact pair densities to allow a description\nof contact (exchange) interactions between charge carriers using first-order\nperturbation theory. Our data indicate that the binding energy of a trion is\ngenerally larger than that of a biexciton in 2D semiconductors. We provide\ninterpolation formulas giving the binding energy and contact density of 2D\nsemiconductors as functions of the electron and hole effective masses and the\nin-plane polarizability."
    },
    {
        "anchor": "Single particle Green's functions and interacting topological insulators: We study topological insulators characterized by the integer topological\ninvariant Z, in even and odd spacial dimensions. These are well understood in\ncase when there are no interactions. We extend the earlier work on this subject\nto construct their topological invariants in terms of their Green's functions.\nIn this form, they can be used even if there are interactions. Specializing to\none and two spacial dimensions, we further show that if two topologically\ndistinct topological insulators border each other, the difference of their\ntopological invariants is equal to the difference between the number of zero\nenergy boundary excitations and the number of zeroes of the Green's function at\nthe boundary. In the absence of interactions Green's functions have no zeroes\nthus there are always edge states at the boundary, as is well known. In the\npresence of interactions, in principle Green's functions could have zeroes. In\nthat case, there could be no edge states at the boundary of two topological\ninsulators with different topological invariants. This may provide an\nalternative explanation to the recent results on one dimensional interacting\ntopological insulators.",
        "positive": "Quantized Non-Volatile Nanomagnetic Synapse based Autoencoder for\n  Efficient Unsupervised Network Anomaly Detection: In the autoencoder based anomaly detection paradigm, implementing the\nautoencoder in edge devices capable of learning in real-time is exceedingly\nchallenging due to limited hardware, energy, and computational resources. We\nshow that these limitations can be addressed by designing an autoencoder with\nlow-resolution non-volatile memory-based synapses and employing an effective\nquantized neural network learning algorithm. We propose a ferromagnetic\nracetrack with engineered notches hosting a magnetic domain wall (DW) as the\nautoencoder synapses, where limited state (5-state) synaptic weights are\nmanipulated by spin orbit torque (SOT) current pulses. The performance of\nanomaly detection of the proposed autoencoder model is evaluated on the NSL-KDD\ndataset. Limited resolution and DW device stochasticity aware training of the\nautoencoder is performed, which yields comparable anomaly detection performance\nto the autoencoder having floating-point precision weights. While the limited\nnumber of quantized states and the inherent stochastic nature of DW synaptic\nweights in nanoscale devices are known to negatively impact the performance,\nour hardware-aware training algorithm is shown to leverage these imperfect\ndevice characteristics to generate an improvement in anomaly detection accuracy\n(90.98%) compared to accuracy obtained with floating-point trained weights.\nFurthermore, our DW-based approach demonstrates a remarkable reduction of at\nleast three orders of magnitude in weight updates during training compared to\nthe floating-point approach, implying substantial energy savings for our\nmethod. This work could stimulate the development of extremely energy efficient\nnon-volatile multi-state synapse-based processors that can perform real-time\ntraining and inference on the edge with unsupervised data."
    },
    {
        "anchor": "Microwave pinning modes near Landau filling $\u03bd=1$ in two-dimensional\n  electron systems with alloy disorder: We report measurements of microwave spectra of two-dimensional electron\nsystems hosted in dilute Al alloy, Al$_x$Ga$_{1-x}$As, for a range of Landau\nlevel fillings, $\\nu$, around 1. For $\\nu>0.8$ or $\\nu<1.2$, the samples\nexhibit a microwave resonance whose frequency decreases as $\\nu$ moves away\nfrom 1. A resonance with this behavior is the signature of solids of\nquasiparticles or -holes in the partially occupied Landau level, which was\npreviously seen in ultralow disorder samples. For $\\nu<0.8$ down to as low as\n$\\nu=0.54$, a resonance in the spectra is still present in the Al\nalloy-disordered samples, though it is partially or completely suppressed at\n$\\nu=3/5$ and $1/2$, and is strongly damped over much of this $\\nu$ range. The\nresonance also shows a striking enhancement in peak frequency for $\\nu$ just\nbelow 3/4. We discuss possible explanations of the resonance behavior for\n$\\nu<0.8$ in terms of the composite fermion picture.",
        "positive": "Continuous wave lasing between Landau levels in graphene: We predict the general feasibility and demonstrate the specific design of the\nTHz laser operating between Landau levels in graphene placed on a polar\nsubstrate in a magnetic field of order 1 T. Steady state operation under a\ncontinuous wave optical pumping is possible due to an interplay between Auger\nand surface-phonon mediated relaxation of carriers. The scheme is scalable to\nother materials with massless Dirac fermions, for example surface states in 3D\ntopological insulators such as Bi$_2$Se$_3$ or Bi$_2$Te$_3$."
    },
    {
        "anchor": "Exchange Splitting of a Hybrid Surface State and Ferromagnetic Order in\n  a 2D Surface Alloy: Surface alloys are highly flexible materials for tailoring the spin-dependent\nproperties of surfaces. Here, we study the spin-dependent band structure of a\nDyAg$_2$ surface alloy formed on an Ag(111) crystal. We find a significant\nexchange spin-splitting of the localized Dy 4f states pointing to a\nferromagnetic coupling between the localized Dy moments at $40\\,$K. The\nmagnetic coupling between these moments is mediated by an indirect, RKKY-like\nexchange coupling via the spin-polarized electrons of the hole-like Dy-Ag\nhybrid surface state.",
        "positive": "Magnetically Tuned Continuous Transition from Weak to Strong Coupling in\n  Terahertz Magnon Polaritons: Depending on the relative rates of coupling and dissipation, a light-matter\ncoupled system is either in the weak- or strong-coupling regime. Here, we\npresent a unique system where the coupling rate continuously increases with an\nexternally applied magnetic field while the dissipation rate remains constant,\nallowing us to monitor a weak-to-strong coupling transition as a function of\nmagnetic field. We observed a Rabi splitting of a terahertz magnon mode in\nyttrium orthoferrite above a threshold magnetic field of ~14 T. Based on a\nmicroscopic theoretical model, we show that with increasing magnetic field the\nmagnons transition into magnon polaritons through an exceptional point, which\nwill open up new opportunities for in situ control of non-Hermitian systems."
    },
    {
        "anchor": "Spin-charge disparity of polarons in organic ferromagnets: Polaron formation in quasi-one-dimensional organic ferromagnets is studied\nbased on an extended Su-Schrieffer-Heeger model combined with a Kondo term. The\ncharge distribution of the polaron is found to be highly asymmetric under\nspatial reflection, due to the spin radicals. On the contrary, the spin density\nis nearly symmetric; the spin asymmetry introduced by the extra electron\ninducing the polaron formation is nearly compensated by the spin polarization\nof the lower-energy states. We discuss these results on the basis of real-space\nmean-field calculations and symmetry arguments.",
        "positive": "Automatic Learning of Topological Phase Boundaries: Topological phase transitions, which do not adhere to Landau's\nphenomenological model (i.e. a spontaneous symmetry breaking process and\nvanishing local order parameters) have been actively researched in condensed\nmatter physics. Machine learning of topological phase transitions has generally\nproved difficult due to the global nature of the topological indices. Only\nrecently has the method of diffusion maps been shown to be effective at\nidentifying changes in topological order. However, previous diffusion map\nresults required adjustments of two hyperparameters: a data length-scale and\nthe number of phase boundaries. In this article we introduce a heuristic that\nrequires no such tuning. This heuristic allows computer programs to locate\nappropriate hyperparameters without user input. We demonstrate this method's\nefficacy by drawing remarkably accurate phase diagrams in three physical\nmodels: the Haldane model of graphene, a generalization of the\nSu-Schreiffer-Haeger (SSH) model, and a model for a quantum ring with tunnel\njunctions. These diagrams are drawn, without human intervention, from a\nsupplied range of model parameters."
    },
    {
        "anchor": "Tails of Localized Density of States of Two-dimensional Dirac Fermions: The density of states of Dirac fermions with a random mass on a\ntwo-dimensional lattice is considered. We give the explicit asymptotic form of\nthe single-electron density of states as a function of both energy and\n(average) Dirac mass, in the regime where all states are localized. We make use\nof a weak-disorder expansion in the parameter g/m^2, where g is the strength of\ndisorder and m the average Dirac mass for the case in which the evaluation of\nthe (supersymmetric) integrals corresponds to non-uniform solutions of the\nsaddle point equation. The resulting density of states has tails which deviate\nfrom the typical pure Gaussian form by an analytic prefactor.",
        "positive": "Simplistic Coulomb forces in molecular dynamics: Comparing the Wolf and\n  shifted-force approximations: This paper compares the Wolf method to the shifted forces (SF) method for\nefficient computer simulation of isotropic systems interacting via Coulomb\nforces, taking results from the Ewald summation method as representing the true\nbehavior. We find that for the Hansen-McDonald molten salt model the SF\napproximation overall reproduces the structural and dynamical properties as\naccurately as does the Wolf method. It is shown that the optimal Wolf damping\nparameter depends on the property in focus, and that neither the potential\nenergy nor the radial distribution function are useful measures for the\nconvergence of theWolf method to the Ewald summation method. The SF\napproximation is also tested for the SPC/Fw model of liquid water at room\ntemperature, showing good agreement with both the Wolf and the particle mesh\nEwald methods; this confirms previous findings [Fennell & Gezelter, J. Chem.\nPhys. {\\bf 124}, 234104 (2006)]. Beside its conceptualsimplicity the SF\napproximation implies a speed-up of a factor 2 to 3 compared to the Wolf method\n(which is in turn much faster than the Ewald method)."
    },
    {
        "anchor": "Edge and corner states in 2D non-Abelian topological insulators from an\n  eigenvector frame rotation perspective: We propose the concept of 2D non-Abelian topological insulator which can\nexplain the energy distributions of the edge states and corner states in\nsystems with parity-time symmetry. From the viewpoint of non-Abelian band\ntopology, we establish the constraints on the 2D Zak phase and polarization. We\ndemonstrate that the corner states in some 2D systems can be explained as the\nboundary mode of the 1D edge states arising from the multi-band non-Abelian\ntopology of the system. We also propose the use of off-diagonal Berry phase as\ncomplementary information to assist the prediction of edge states in\nnon-Abelian topological insulators. Our work provides an alternative approach\nto study edge and corner modes and this idea can be extended to 3D systems.",
        "positive": "Local vibrational mode of impurity in a monatomic linear chain under\n  open and periodic boundary conditions: In this paper, we revisit the lattice vibration of one-dimensional monatomic\nlinear chain under open and periodic boundary conditions, and give the exact\nconditions for the emergence of the local vibration mode when one of the atoms\nis replaced by an impurity. Our motivation is twofold. Firstly, in deriving the\ndispersion relation of the atoms, periodic boundary condition is overwhelmingly\nutilized while open boundary condition is seldomly referred. Therefore we\nmanage to obtain the dispersion relation under both boundary conditions\nsimultaneously by Molinari formula. Secondly, in the presence of impurity,\nlocal vibration mode can emerge as long as the mass of the impurity $m'$ is\nsmaller than the mass of the perfect atom $m$ to certain degree, which can be\nmeasured by the mass ratio $\\delta=\\frac{m-m'}{m}$. At periodic boundary\ncondition, the critical mass ratio is $0$ or $\\frac{1}{N}$, depending on\nwhether the length $N$ of the chain is even or odd. At open boundary condition,\nthe critical mass ratio is $\\frac{N}{2N-1}$ if the impurity locates at the end\nof the chain, while it is $\\frac{N}{(2N_l+1)(2N_r+1)}$ with $N_l$ and $N_r$ be\nthe number of atoms at the left and right hand sides of the impurity if the\nimpurity locates at the middle."
    },
    {
        "anchor": "Effect of Meissner screening and trapped magnetic flux on magnetization\n  dynamics in thick Nb/Ni80Fe20/Nb trilayers: We investigate the influence of Meissner screening and trapped magnetic flux\non magnetization dynamics for a Ni80Fe20 film sandwiched between two thick Nb\nlayers (100 nm) using broadband (5-20 GHz) ferromagnetic resonance (FMR)\nspectroscopy. Below the superconducting transition Tc of Nb, significant\nzero-frequency line broadening (5-6 mT) and DC resonance field shift (50 mT) to\na low field are both observed if the Nb thickness is comparable to the London\npenetration depth of Nb films (>= 100 nm). We attribute the observed peculiar\nbehaviors to the increased incoherent precession near the Ni80Fe20/Nb interface\nand the effectively focused magnetic flux in the middle Ni80Fe20 caused by\nstrong Meissner screening and (defect-)trapped flux of the thick adjacent Nb\nlayers. This explanation is supported by static magnetic properties of the\nsamples and comparison with FMR data on thick Nb/Ni80Fe20 bilayers. Great care\nshould therefore be taken in the analysis of FMR response in ferromagnetic\nJosephson structures with thick superconductors, a fundamental property for\nhigh-frequency device applications of spin-polarized supercurrents.",
        "positive": "Valence state manipulation of single Fe impurities in GaAs by STM: The incorporation of Fe in GaAs was studied by cross-sectional scanning\ntunneling microscopy (X-STM). The observed local electronic contrast of a\nsingle Fe atom is found to depend strongly on its charge state. We demonstrate\nthat an applied tip voltage can be used to manipulate the valence and spin\nstate of single Fe impurities in GaAs. In particular we can induce a transition\nfrom the Fe{3+)- 3d5 - isoelectronic state to the Fe{2+} - 3d6 - ionized\nacceptor state with an associated change of the spin moment. Fe atoms sometimes\nproduce dark anisotropic features in topographic maps, which is consistent with\nan interference between different tunneling paths."
    },
    {
        "anchor": "Transition to Landau Levels in Graphene Quantum Dots: We investigate the electronic eigenstates of graphene quantum dots of\nrealistic size (i.e., up to 80 nm diameter) in the presence of a perpendicular\nmagnetic field B. Numerical tight-binding calculations and Coulomb-blockade\nmeasurements performed near the Dirac point exhibit the transition from the\nlinear density of states at B=0 to the Landau level regime at high fields.\nDetails of this transition sensitively depend on the underlying graphene\nlattice structure, bulk defects, and localization effects at the edges. Key to\nthe understanding of the parametric evolution of the levels is the strength of\nthe chiral-symmetry breaking K-K' scattering. We show that the parametric\nvariation of the level variance provides a quantitative measure for this\nscattering mechanism. We perform measurements of the parametric motion of\nCoulomb blockade peaks as a function of magnetic field and find good agreement.\nWe thereby demonstrate that the magnetic-field dependence of graphene energy\nlevels may serve as a sensitive indicator for the properties of graphene\nquantum dots and, in further consequence, for the validity of the\nDirac-picture.",
        "positive": "Order, disorder and tunable gaps in the spectrum of Andreev bound states\n  in a multi-terminal superconducting device: We consider the spectrum of Andreev bound states (ABSs) in an exemplary\n4-terminal superconducting structure where 4 chaotic cavities are connected by\nQPCs to the terminals and to each other forming a ring. Such a tunable device\ncan be realized in 2DEG-superconductor structures.\n  We concentrate on the limit of a short structure and large conductance of the\nQPCs where a quasi-continuous spectrum is formed. The energies can be tuned by\nthe superconducting phases. We observe the opening and closing of gaps in the\nspectrum. This concerns the usual proximity gap that separates the levels from\nzero energy as well as less usual \"smile\" gaps that split the levels of the\nspectrum.\n  We demonstrate a remarkable crossover in the overall spectrum that occurs\nupon changing the ratio of conductance of the inner and outer QPCs. At big\nvalues of the ratio, the levels exhibit a generic behavior expected for the\nspectrum of a disordered system manifesting level repulsion and \"Brownian\nmotion\" upon changing the phases. At small values of the ratio, the levels are\nsqueezed into narrow bunches separated by wide smile gaps. Each bunch consists\nof almost degenerate ABSs.\n  We study in detail the properties of the spectrum in the limit of a small\nratio, paying special attention to the crossings of bunches. We distinguish two\ntypes of crossings: i. with a regular phase dependence of the levels and ii.\ncrossings where the Brownian motion of the levels leads to an apparently\nirregular phase-dependence. We work out a perturbation theory to explain the\nobservations.\n  The unusual properties of the spectrum originate from unobvious topological\neffects. Topology of the first kind is related to the winding of the\nsemiclassical Green's function. It is responsible for the proximity gaps.\nTopology of the second kind comes about the discreteness of the number of modes\nand is responsible for the smile gaps."
    },
    {
        "anchor": "Polarized Electric Current in Semiclassical Transport with Spin-Orbit\n  Interaction: Semiclassical solutions of two-dimensional Schrodinger equation with\nspin-orbit interaction and smooth potential are considered. In the leading\norder, spin polarization is in-plane and follows the evolution of the electron\nmomentum for a given subband. Out-of-plane spin polarization appears as a\nquantum correction, for which an explicit expression is obtained. We\ndemonstrate how spin-polarized currents can be achieved with the help of a\nbarrier or quantum point contact open for transmission only in the lower\nsubband.",
        "positive": "Optical Measurement of Pseudo-Spin Texture of the Exciton Fine-Structure\n  in Monolayer WSe2 within the Light Cone: Several theoretical predictions have claimed that the neutral exciton of\nTMDCs splits into a transversal and longitudinal exciton branch, with the\nlongitudinal one, which is the upper branch, exhibiting an extraordinary strong\ndispersion in the meV range within the light cone. Historically, this was\nlinked for semiconductor quantum wells to strong far-field optical dipole\ncoupling, or strong electronic long-range exchange interactions, describing two\nsides of the same coin. Recently, experiments utilizing Fourier-space\nspectroscopy have shown that the exciton (exciton-polariton) dispersion can\nindeed be measured for high-quality hexagonal-BN-encapsulated WSe2 monolayer\nsamples and can confirm the energy scale. Here, the exciton fine-structure's\npseudo-spin and the valley polarization are investigated as a function of the\ncentre-of-mass-momentum and excitation-laser detuning. For quasi-resonant\nexcitation, a strong dispersion featuring a pronounced momentum-dependent\nhelicity is observed. By increasing the excitation energy step-wise towards and\nthen above the electronic band gap, the dispersion and the helicity\nsystematically decrease due to contributions of incoherent excitons and\nemission from plasma. The decline of the helicity with centre-of-mass momentum\ncan be phenomenologically modelled by the Maialle-Silva-Sham mechanism using\nthe exciton splitting as the source of an effective magnetic field."
    },
    {
        "anchor": "Non-trivial quantum oscillation geometric phase shift in a trivial band: The accumulation of non-trivial geometric phases in a material's response is\noften a tell-tale sign of a rich underlying internal structure. Studying\nquantum oscillations provides one of the ways to determine these geometrical\nphases, such as Berry's phase, that play a central role in topological quantum\nmaterials. We report on magneto-transport measurements in ABA-trilayer\ngraphene, the band structure of which is comprised of a weakly gapped linear\nDirac band, nested within a trivial quadratic band. Here we show Shubnikov-de\nHaas (SdH) oscillations of the quadratic band shifted by a phase that sharply\ndeparts from the expected 2$\\pi$ Berry's phase. Our analysis reveals that,\nsurprisingly, the anomalous phase shift is non-trivial and is inherited from\nthe non-trivial Berry's phase of the linear Dirac band due to strong\nfilling-enforced constraints between the linear and quadratic band Fermi\nsurfaces. Given that many topological materials contain multiple bands, our\nwork indicates how additional bands, which are thought to obscure the analysis,\ncan actually be exploited to tease out the subtle effects of Berry's phase.",
        "positive": "Quantum Hall effect in exfoliated graphene affected by charged\n  impurities: metrological measurements: Metrological investigations of the quantum Hall effect (QHE) completed by\ntransport measurements at low magnetic field are carried out in\na-few-$\\mu\\mathrm{m}$-wide Hall bars made of monolayer (ML) or bilayer (BL)\nexfoliated graphene transferred on $\\textrm{Si/SiO}_{2}$ substrate. From the\ncharge carrier density dependence of the conductivity and from the measurement\nof the quantum corrections at low magnetic field, we deduce that transport\nproperties in these devices are mainly governed by the Coulomb interaction of\ncarriers with a large concentration of charged impurities. In the QHE regime,\nat high magnetic field and low temperature ($T<1.3 \\textrm{K}$), the Hall\nresistance is measured by comparison with a GaAs based quantum resistance\nstandard using a cryogenic current comparator. In the low dissipation limit, it\nis found quantized within 5 parts in $10^{7}$ (one standard deviation, $1\n\\sigma$) at the expected rational fractions of the von Klitzing constant,\nrespectively $R_{\\mathrm{K}}/2$ and $R_{\\mathrm{K}}/4$ in the ML and BL\ndevices. These results constitute the most accurate QHE quantization tests to\ndate in monolayer and bilayer exfoliated graphene. It turns out that a main\nlimitation to the quantization accuracy, which is found well above the\n$10^{-9}$ accuracy usually achieved in GaAs, is the low value of the QHE\nbreakdown current being no more than $1 \\mu\\mathrm{A}$. The current dependence\nof the longitudinal conductivity investigated in the BL Hall bar shows that\ndissipation occurs through quasi-elastic inter-Landau level scattering,\nassisted by large local electric fields. We propose that charged impurities are\nresponsible for an enhancement of such inter-Landau level transition rate and\ncause small breakdown currents."
    },
    {
        "anchor": "Dephasing due to nuclear spins in large-amplitude electric dipole spin\n  resonance: We have analyzed effects of the hyperfine interaction on electric dipole spin\nresonance when the amplitude of the quantum-dot motion becomes comparable or\nlarger than the quantum dot's size. Away from the well known small-drive\nregime, the important role played by transverse nuclear fluctuations leads to a\ngaussian decay with characteristic dependence on drive strength and detuning. A\ncharacterization of spin-flip gate fidelity, in the presence of such additional\ndrive-dependent dephasing, shows that vanishingly small errors can still be\nachieved at sufficiently large amplitudes. Based on our theory, we analyze\nrecent electric-dipole spin resonance experiments relying on spin-orbit\ninteractions or the slanting field of a micromagnet. We find that such\nexperiments are already in a regime with significant effects of transverse\nnuclear fluctuations and the form of decay of the Rabi oscillations can be\nreproduced well by our theory.",
        "positive": "Spin-pumping and Enhanced Gilbert Damping in Thin Magnetic Insulator\n  Films: Precessing magnetization in a thin film magnetic insulator pumps spins into\nadjacent metals; however, this phenomenon is not quantitatively understood. We\npresent a theory for the dependence of spin-pumping on the transverse mode\nnumber and in-plane wave vector. For long-wavelength spin waves, the enhanced\nGilbert damping for the transverse mode volume waves is twice that of the\nmacrospin mode, and for surface modes, the enhancement can be ten or more times\nstronger. Spin-pumping is negligible for short-wavelength exchange spin waves.\nWe corroborate our analytical theory with numerical calculations in agreement\nwith recent experimental results."
    },
    {
        "anchor": "Feynman-Vernon influence functional approach to quantum transport in\n  interacting nanojunctions: An analytical hierarchical study: We present a nonperturbative and formally exact approach for the charge\ntransport in interacting nanojunctions based on a real time path integral\nformulation of the reduced system dynamics. An expansion of the influence\nfunctional in terms of the number of tunneling transitions, and integration of\nthe Grassmann variables between the tunneling times, allows us to obtain a\nstill exact generalized master equation (GME) for the populations of the\nreduced density matrix (RDM) in the occupation number representation, as well\nas a formally exact expression for the current. By borrowing the nomenclature\nof the famous spin-boson problem, we characterize the two-state dynamics of\nsuch degrees of freedom on the forward and backward branches in terms of single\nfour-state paths with alternating blips and sojourns. This allows a\ndiagrammatic representation of the GME kernel and its parametrization in terms\nof sequences of blips and sojourns. We apply our formalism to the exactly\nsolvable resonant level model (RLM) and to the the single impurity Anderson\nmodel (SIAM). We demonstrate a hierarchical diagrammatic structure of the exact\nGME kernel. While the hierarchy closes at the second-tier level for the RLM,\nthis is not the case for the interacting SIAM. Upon inspection of the GME,\nknown results from various perturbative and nonperturbative approximation\nschemes to quantum transport in the SIAM are recovered. Finally, a noncrossing\napproximation for the hierarchical kernel is developed, which enables us to\nsystematically decrease temperature at each next level of the approximation.\nAnalytical results are presented, both in equilibrium and nonequilibrium,\nincluding the case of an applied magnetic field.",
        "positive": "Observation of propagating edge spin waves modes: Broadband magnetization response of equilateral triangular 1000 nm Permalloy\ndots has been studied under an in-plane magnetic field, applied parallel\n(buckle state) and perpendicular (Y state) to the triangles base. Micromagnetic\nsimulations identify edge spin waves (E-SWs) in the buckle state as SWs\npropagating along the two adjacent edges. These quasi one-dimensional spin\nwaves emitted by the vertex magnetic charges gradually transform from\npropagating to standing due to interference and are weakly affected by dipolar\ninterdot interaction and variation of the aspect ratio. Spin waves in the Y\nstate have a two dimensional character. These findings open perspectives for\nimplementation of the E-SWs in magnonic crystals and thin films."
    },
    {
        "anchor": "Continuum elastic model of fullerenes and the sphericity of the carbon\n  onion shells: A continuum elastic model of fullerenes is presented by utilizing the analogy\nbetween the closed carbon cages and elastic shells. We derive expressions for\nthe curvature related strain energies Ep of the pentagonal protrusions. We\npropose to explain the observed sphericity of the carbon onions shells as\nopposed to the predicted protrusions around the pentagonal defects on the basis\nof our continuum elastic model of fullerenes. In our model the energy inherent\nin the pentagonal protrusions Ep is due to the stretching and bending of the\nshell and shown to be a function of the structural parameters. It also defines\nthe upper limit on the size of the free-standing fullerenes. Using Ep and the\ntopological arguments, we show that the pentagonal protrusions will be smoothed\nout, resulting in spherical shells of the carbon onions denoted as\nC60@C240@C540@C960@C1500 ,... .",
        "positive": "Macroscopic graphene membranes and their extraordinary stiffness: The properties of suspended graphene are currently attracting enormous\ninterest, but the small size of available samples and the difficulties in\nmaking them severely restrict the number of experimental techniques that can be\nused to study the optical, mechanical, electronic, thermal and other\ncharacteristics of this one-atom-thick material. Here we describe a new and\nhighly-reliable approach for making graphene membranes of a macroscopic size\n(currently up to 100 microns in diameter) and their characterization by\ntransmission electron microscopy. In particular, we have found that long\ngraphene beams supported by one side only do not scroll or fold, in striking\ncontrast to the current perception of graphene as a supple thin fabric, but\ndemonstrate sufficient stiffness to support extremely large loads, millions of\ntimes exceeding their own weight, in agreement with the presented theory. Our\nwork opens many avenues for studying suspended graphene and using it in various\nmicromechanical systems and electron microscopy."
    },
    {
        "anchor": "Spin-polarized transport through domain wall in magnetized graphene: Atomically thin two-dimensional layer of honeycomb crystalline carbon known\nas graphene is a promising system for electronics. It has a point-like Fermi\nsurface, which is very sensitive to external potentials. In particular, Zeeman\nmagnetic field parallel to the graphene layer splits electron bands and creates\nfully spin-polarized and geometrically congruent circular Fermi surfaces of\nparticle and hole type. In the presence of electric field, particles and holes\nwith opposite spins drift in opposite direction. These phenomena are likely to\nbe of interest for developing graphene-based spintronic devices. A domain wall\n(DW) separating regions with opposite spin polarizations is a basic element of\nsuch a device. Here we consider a ballistic passage of spin-polarized charge\ncarriers through DW in graphene. We also discuss the analogy between the\ngeneration of spin currents in graphene and in relativistic quark-gluon plasma,\nwhere the spin-polarized current is responsible for the phenomenon of charge\nseparation studied recently at RHIC.",
        "positive": "Continuous quantum measurement of two coupled quantum dots using a point\n  contact: A quantum trajectory approach: We obtain the finite-temperature unconditional master equation of the density\nmatrix for two coupled quantum dots (CQD) when one dot is subjected to a\nmeasurement of its electron occupation number using a point contact (PC). To\ndetermine how the CQD system state depends on the actual current through the PC\ndevice, we use the so-called quantum trajectory method to derive the\nzero-temperature conditional master equation. We first treat the electron\ntunneling through the PC barrier as a classical stochastic point process (a\nquantum-jump model). Then we show explicitly that our results can be extended\nto the quantum-diffusive limit when the average electron tunneling rate is very\nlarge compared to the extra change of the tunneling rate due to the presence of\nthe electron in the dot closer to the PC. We find that in both quantum-jump and\nquantum-diffusive cases, the conditional dynamics of the CQD system can be\ndescribed by the stochastic Schr\\\"{o}dinger equations for its conditioned state\nvector if and only if the information carried away from the CQD system by the\nPC reservoirs can be recovered by the perfect detection of the measurements."
    },
    {
        "anchor": "Femtosecond spin-state switching dynamics of spin-crossover molecules\n  condensed in thin films: The photoinduced switching of Fe(II)-based spin-crossover complexes from\nsinglet to quintet takes place at ultrafast time scales. This a priori\nspin-forbidden transition triggered numerous time-resolved experiments of\nsolvated samples to elucidate the mechanism at play. The involved intermediate\nstates remain uncertain. We apply ultrafast x-ray spectroscopy in molecular\nfilms as a method sensitive to spin, electronic, and nuclear degrees of\nfreedom. Combining the progress in molecule synthesis and film growth with the\nopportunities at x-ray free-electron lasers, we analyze the transient evolution\nof the Fe L3 fine structure at room temperature. Our measurements and\ncalculations indicate the involvement of an Fe triplet intermediate state. The\nhigh-spin state saturates at half of the available molecules, limited by\nmolecule-molecule interaction within the film.",
        "positive": "Hyperfine-driven persistent currents in mesoscopic rings based on a 2D\n  electron gas with Rashba spin-orbit interaction: We present a detailed theory of induced persistent current produced by\nhyperfine interaction in mesoscopic rings based on a 2D-electron (hole) gas in\nthe absence of external magnetic field. The persistent current emerges due to\ncombined action of the hyperfine interaction of charge carriers with polarized\nnuclei, spin-orbit interaction and Berry phase."
    },
    {
        "anchor": "The Nonperiodic Anyon Model and the Fractional Quantum Hall Effect: The lowest-Landau-level anyon model becomes nonperiodic in the statistics\nparameter when the finite size of the attached flux tubes is taken into\naccount. The finite-size effects cause the inverse proportional relation\nbetween the critical filling factor and the statistics parameter to be\nnonperiodically continued in the screening regime, where the fluxes are\nanti-parallel to the external magnetic field -- at critical filling, the\nexternal magnetic field is entirely screened by the mean magnetic field\nassociated with the flux tubes. A clustering argument is proposed to select\nparticular values of the statistics parameter. In this way, IQHE and FQHE\nfillings are obtained in terms of gapped nondegenerate LLL-anyonic wave\nfunctions. Jain's series are reproduced without the need to populate higher\nLandau levels. New FQHE series are proposed, like, in particular, the\nparticle-hole complementary series of the Laughlin one. For fast-rotating\nBose-Einstein condensates, a corresponding clustering argument yields\nparticular fractional filling series.",
        "positive": "Real-time two-axis control of a spin qubit: Optimal control of qubits requires the ability to adapt continuously to their\never-changing environment. We demonstrate a real-time control protocol for a\ntwo-electron singlet-triplet qubit with two fluctuating Hamiltonian parameters.\nOur approach leverages single-shot readout classification and dynamic waveform\ngeneration, allowing full Hamiltonian estimation to dynamically stabilize and\noptimize the qubit performance. Powered by a field-programmable gate array\n(FPGA), the quantum control electronics estimates the Overhauser field gradient\nbetween the two electrons in real time, enabling controlled Overhauser-driven\nspin rotations and thus bypassing the need for micromagnets or nuclear\npolarization protocols. It also estimates the exchange interaction between the\ntwo electrons and adjusts their detuning, resulting in extended coherence of\nHadamard rotations when correcting for fluctuations of both qubit axes. Our\nstudy emphasizes the critical role of feedback in enhancing the performance and\nstability of quantum devices affected by quasistatic noise. Feedback will play\nan essential role in improving performance in various qubit implementations\nthat go beyond spin qubits, helping realize the full potential of quantum\ndevices for quantum technology applications."
    },
    {
        "anchor": "Even denominator fractional quantum Hall state in bilayer graphene: The multi-component nature of bilayer graphene (BLG), together with the\nability to controllably tune between the various ground state orders, makes it\na rich system in which to explore interaction driven phenomena. In the\nfractional quantum Hall effect (FQHE) regime, the unique Landau level spectrum\nof BLG is anticipated to support a non-Abelian even-denominator state that is\ntunable by both electric and magnetic fields. However, observation of this\nstate, which is anticipated to be stronger than in conventional systems, has\nbeen conspicuously difficult. Here we report transport measurements of a robust\neven denominator FQHE in high-mobility, dual gated BLG devices. We confirm that\nthe stability of the energy gap can be sensitively tuned and map the phase\ndiagram. Our results establish BLG as a dynamic new platform to study\ntopological ground states with possible non-Abelian excitations.",
        "positive": "Nonperturbative interaction effects in the thermodynamics of disordered\n  wires: We study nonperturbative interaction corrections to the thermodynamic\nquantities of multichannel disordered wires in the presence of the Coulomb\ninteractions. Within the replica nonlinear $\\sigma$-model (NL$\\sigma$M)\nformalism, they arise from nonperturbative soliton saddle points of the\nNL$\\sigma$M action. The problem is reduced to evaluating the partition function\nof a replicated classical one dimensional Coulomb gas. The state of the latter\ndepends on two parameters: the number of transverse channels in the wire,\nN_{ch}, and the dimensionless conductance, G(L_T), of a wire segment of length\nequal to the thermal diffusion length, L_T. At relatively high temperatures,\n$G(L_T) \\gtrsim \\ln N_{ch} $, the gas is dimerized, i.e. consists of bound\nneutral pairs. At lower temperatures, $\\ln N_{ch} \\gtrsim G(L_T) \\gtrsim 1$,\nthe pairs overlap and form a Coulomb plasma. The crossover between the two\nregimes occurs at a parametrically large conductance $G(L_T) \\sim \\ln N_{ch}$,\nand may be studied independently from the perturbative effects. Specializing to\nthe high temperature regime, we obtain the leading nonperturbative correction\nto the wire heat capacity. Its ratio to the heat capacity for noninteracting\nelectrons, C_0, is $\\delta C/C_0\\sim N_{ch}G^2(L_T)e^{-2G(L_T)}$."
    },
    {
        "anchor": "Large Current Modulation and Spin-Dependent Tunneling of Vertical\n  Graphene/MoS$_{2}$ Heterostructures: Vertical graphene heterostructures have been introduced as an alternative\narchitecture for electronic devices by using quantum tunneling. Here, we\npresent that the current on/off ratio of vertical graphene field-effect\ntransistors is enhanced by using an armchair graphene nanoribbon as an\nelectrode. Moreover, we report spin-dependent tunneling current of the\ngraphene/MoS2 heterostructures. When an atomically thin MoS2 layer sandwiched\nbetween graphene electrodes becomes magnetic, Dirac fermions with different\nspins feel different height of the tunnel barrier, leading to spin-dependent\ntunneling. Our finding will develop the present graphene heterostructures for\nelectronic devices by improving the device performance and by adding the\npossibility of spintronics based on graphene.",
        "positive": "Weak Localisation in Clean and Highly Disordered Graphene: We look at the magnetic field induced weak localisation peak of graphene\nsamples with different mobilities. At very low temperatures, low mobility\nsamples exhibit a very broad peak as a function of the magnetic field, in\ncontrast to higher mobility samples, where the weak localisation peak is very\nsharp. We analyze the experimental data in the context of the localisation\nlength, which allows us to extract, both the localisation length and the phase\ncoherence length of the samples, regardless of their mobilities. This analysis\nis made possible by the observation that the localisation length undergoes a\ngeneric weak localisation dependence with striking universal properties."
    },
    {
        "anchor": "Abnormal magnetoresistance behavior in Nb thin film with rectangular\n  antidot lattice: Abnormal magnetoresistance behavior is found in superconducting Nb films\nperforated with rectangular arrays of antidots (holes). Generally\nmagnetoresistance were always found to increase with increasing magnetic field.\nHere we observed a reversal of this behavior for particular in low temperature\nor current density. This phenomenon is due to a strong 'caging effect' which\ninterstitial vortices are strongly trapped among pinned multivortices.",
        "positive": "Non-equilibrium quasiparticles in superconducting circuits: photons vs.\n  phonons: We study the effect of non-equilibrium quasiparticles on the operation of a\nsuperconducting device (a qubit or a resonator), including heating of the\nquasiparticles by the device operation. Focusing on the competition between\nheating via low-frequency photon absorption and cooling via photon and phonon\nemission, we obtain a remarkably simple non-thermal stationary solution of the\nkinetic equation for the quasiparticle distribution function. We estimate the\ninfluence of quasiparticles on relaxation and excitation rates for transmon\nqubits, and relate our findings to recent experiments."
    },
    {
        "anchor": "A gate-defined silicon quantum dot molecule: We report electron transport measurements of a silicon double dot formed in\nmulti-gated metal-oxide-semiconductor structures with a 15-nm-thick\nsilicon-on-insulator layer. Tunable tunnel coupling enables us to observe an\nexcitation spectrum in weakly coupled dots and an energy level anticrossing in\nstrongly coupled ones. Such a quantum dot molecule with both charge and energy\nquantization provides the essential prerequisite for future implementation of\nsilicon-based quantum computations.",
        "positive": "Reliable modeling of weak antilocalization for accurate spin-lifetime\n  extraction: We examine models for the magneto-conductivity correction in 2DEGs with both\nRashba and Dresselhaus spin-orbit coupling (SOC) for their applicability to\nexperimental data fitting. In particular, we compare the Landau-quantized\nCooperon approach, which is mostly only numerically treatable, and the\nquasi-classical approximation that was recently employed to obtain an explicit\nsolution for arbitrary Rashba and Dresselhaus SOC [PRL 112, 156601 (2019)]. It\nis found that the quasi-classical approximation yields significantly different\nresults even to lowest order in the magnetic field and appears unsuitable for\nreliable parameter fitting. The discrepancy emerges when a sum over Landau\nlevels is replaced by an integral over wave vectors. Substantial improvement is\nachieved by supplementing the quasi-classical model with the first two\ncorrections given by the Euler-MacLaurin formula. Corresponding modifications\nare, however, only feasible in special SOC parameter configurations where the\nmixing of Landau bands is negligible and a closed-form solution that accounts\nfor Landau quantization is also available. Such a scenario appears in a\nparameter regime where a persistent spin helix emerges and a transition between\nweak anti- and weak localization takes place. Combining recent findings, we\nderive a generalized closed-form expression for the magneto-conductivity\ncorrection applicable to generic 2DEGs that are grown along a crystal direction\nwith at least two growth-direction Miller indices equal in modulus. The result\nis a function of spin lifetimes of the long-lived spin textures and is valid\nclose to the persistent-spin-helix regime. The accuracy of the derived formula\nis validated by comparing with results from numerical diagonalization of the\nmultiband Cooperon as well as a recently established Monte-Carlo-based\nreal-space simulation in exemplary (001)-, (113)-, and (110)-2DEGs."
    },
    {
        "anchor": "Unconventional dc transport in Rashba electron gases: We discuss the transport properties of a disordered two-dimensional electron\ngas with strong Rashba spin-orbit coupling. We show that in the high-density\nregime where the Fermi energy overcomes the energy associated with spin-orbit\ncoupling, dc transport is accurately described by a standard Drude's law, due\nto a non-trivial compensation between the suppression of back-scattering and\nthe relativistic correction to the quasi-particle velocity. On the contrary,\nwhen the system enters the opposite dominant spin-orbit regime, Drude's\nparadigm breaks down and the dc conductivity becomes strongly sensitive to the\nspin-orbit coupling strength, providing a suitable tool to test the\nentanglement between spin and charge degrees of freedom in these",
        "positive": "Josephson array of mesoscopic objects. Modulation of system properties\n  through the chemical potential: The phase diagram of a two-dimensional Josephson array of mesoscopic objects\nis examined. Quantum fluctuations in both the modulus and phase of the\nsuperconducting order parameter are taken into account within a lattice boson\nHubbard model. Modulating the average occupation number $n_0$ of the sites in\nthe system leads to changes in the state of the array, and the character of\nthese changes depends significantly on the region of the phase diagram being\nexamined. In the region where there are large quantum fluctuations in the phase\nof the superconducting order parameter, variation of the chemical potential\ncauses oscillations with alternating superconducting (superfluid) and normal\nstates of the array. On the other hand, in the region where the bosons interact\nweakly, the properties of the system depend monotonically on $n_0$. Lowering\nthe temperature and increasing the particle interaction force lead to a\nreduction in the width of the region of variation in $n_0$ within which the\nsystem properties depend weakly on the average occupation number. The phase\ndiagram of the array is obtained by mapping this quantum system onto a\nclassical two-dimensional XY model with a renormalized Josephson coupling\nconstant and is consistent with our quantum Path-Integral Monte Carlo\ncalculations."
    },
    {
        "anchor": "Effects of Exchange Symmetry on Full Counting Statistics: We study the full counting statistics for the transmission of two identical\nparticles with positive or negative symmetry under exchange for the situation\nwhere the scattering depends on energy. We find that, besides the expected\nsensitivity of the noise and higher cumulants, the exchange symmetry has a huge\neffect on the average transmitted charge; for equal-spin exchange-correlated\nelectrons, the average transmitted charge can be orders of magnitude larger\nthan the corresponding value for independent electrons. A similar, although\nsmaller, effect is found in a four-lead geometry even for energy-independent\nscattering.",
        "positive": "Multi-harmonic Quantum Dot Optomechanics in fused LiNbO$_3$-(Al)GaAs\n  hybrids: We fabricated an acousto-optic semiconductor hybrid device for strong\noptomechanical coupling of individual quantum emitters and a surface acoustic\nwave. Our device comprises a surface acoustic wave chip made from highly\npiezoelectric LiNbO$_3$ and a GaAs-based semiconductor membrane with an\nembedded layer of quantum dots. Employing multi-harmonic transducers, we\ngenerated sound waves on LiNbO$_3$ over a wide range of radio frequencies. We\nmonitored their coupling to and propagation across the semiconductor membrane\nboth in the electrical and optical domain. We demonstrate enhanced\noptomechanical tuning of the embedded quantum dots with increasing frequencies.\nThis effect was verified by finite element modelling of our device geometry and\nattributed to an increased localization of the acoustic field within the\nsemiconductor membrane. For moderately high acoustic frequencies, our\nsimulations predict strong optomechanical coupling making our hybrid device\nideally suited for applications in semiconductor based quantum acoustics."
    },
    {
        "anchor": "Enhancement of thermoelectric performance of a nanoribbon made of\n  alpha-$\\mathcal{T}_3$ lattice: We present electronic and transport properties of a zigzag nanoribbon made of\nalpha-$\\mathcal{T}_3$ lattice. Our particular focus is on the effects of the\ncontinous evolution of the edge modes ( from flat to dispersive) on the\nthermoelectric transport properties. Unlike the case of graphene nanoribbon,\nthe zigzag nanoribbon of $\\alpha-\\mathcal{T}_3$ lattice can host a pair of\ndispersive (chiral) edge modes at the two valleys for specific width of the\nribbon. Moreover, gap opening can also occur at the two valleys depending on\nthe width. The slope of the chiral edge modes and the energy gap strongly\ndepend on the relative strength of two kinds of hoping parameters present in\nthe system. We compute corresponding transport coefficients such as\nconductance, thermopower, thermalconductivity and the thermoelectric figure of\nmerits by using the tight-binding Green function formalism, in order to explore\nthe roles of the dispersive edge modes. It is found that the thermopower and\nthermoelectric figure of merits can be enhanced significantly by suitably\ncontrolling the edge modes. The figure of merits can be enhanced by ten times\nunder suitable parameter regime in comparison to the case of graphene. Finally,\nwe reveal that the presence of line defect, close to the edge, can cause a\nsignificant impact on the edge modes as well as on electrical conductance.\nHowever, thermopower is relatively less sensitive to such defects.",
        "positive": "Landau Level Collapse in Gated Graphene Structures: We describe a new regime of magnetotransport in two dimensional electron\nsystems in the presence of a narrow potential barrier imposed by external\ngates. In such systems, the Landau level states, confined to the barrier region\nin strong magnetic fields, undergo a deconfinement transition as the field is\nlowered. We present transport measurements showing Shubnikov-de Haas (SdH)\noscillations which, in the unipolar regime, abruptly disappear when the\nstrength of the magnetic field is reduced below a certain critical value. This\nbehavior is explained by a semiclassical analysis of the transformation of\nclosed cyclotron orbits into open, deconfined trajectories. Comparison to\nSdH-type resonances in the local density of states is presented."
    },
    {
        "anchor": "Ferromagnetic resonance modes in the exchange dominated limit in\n  cylinders of finite length: We analyze the magnetic mode structure of axially-magnetized, finite-length,\nnanoscopic cylinders in a regime where the exchange interaction dominates,\nalong with simulations of the mode frequencies of the ferrimagnet yttrium iron\ngarnet. For the bulk modes we find that the frequencies can be represented by\nan expression given by Herring and Kittel by using wavevector components\nobtained by fitting the mode patterns emerging from these simulations. In\naddition to the axial, radial, and azimuthal modes that are present in an\ninfinite cylinder, we find localized \"cap modes\" that are \"trapped\" at the top\nand bottom cylinder faces by the inhomogeneous dipole field emerging from the\nends. Semi-quantitative explanations are given for some of the modes in terms\nof a one-dimensional Schrodinger equation which is valid in the exchange\ndominant case. The assignment of the azimuthal mode number is carefully\ndiscussed and the frequency splitting of a few pairs of nearly degenerate modes\nis determined through the beat pattern emerging from them.",
        "positive": "Dirac Fermion Hierarchy of Composite Fermi Liquids: Composite Fermi liquids (CFLs) are compressible states that can occur for 2D\ninteracting fermions confined in the lowest Landau level at certain Landau\nlevel fillings. They have been understood as Fermi seas formed by composite\nfermions which are bound states of electromagnetic fluxes and electrons as\nreported by Halperin, Lee and Read [Phys. Rev. B 47, 7312 (1993)]. At half\nfilling, an explicitly particle-hole symmetric theory based on Dirac fermions\nwas proposed by Son [Phys. Rev. X 5, 031027 (2015)] as an alternative low\nenergy description. In this work, we investigate the Berry curvature of CFL\nmodel wave functions at a filling fraction one-quarter, and observe that it is\nuniformly distributed over the Fermi sea except at the center where an\nadditional $\\pi$ phase was found. Motivated by this, we propose an effective\ntheory which generalizes Son's half filling theory, by internal gauge flux\nattachment, to all filling fractions in which fermionic CFLs can occur. The\nnumerical results support the idea of internal gauge flux attachment."
    },
    {
        "anchor": "Scattering wave function approach to multi-terminal mesoscopic system\n  with spin-orbit coupling: In this paper,we present a detailed formulation to solve the scattering wave\nfunction for a multi-terminal mesoscopic system with spin-orbit coupling. In\naddition to terminal currents, all local quantities can be calculated\nexplicitly by taking proper ensemble average in the Landauer-Buttiker's spirit\nusing the scattering wave functions. Based on this formulation, we derive some\nrigorous results for equilibrium state. Furthermore, some new symmetry\nrelations are found for the typical two terminal structure in which a\nsemiconductor bar with Rashba or/and Dresselhaus SO coupling is sandwiched\nsymmetrically between two leads. These symmetry property can provide accuracy\ntests for experimental measurements and numerical calculations.",
        "positive": "Helical Andreev bound states and superconducting Klein tunneling in\n  topological insulator Josephson junctions: Currently, much effort is being put into detecting unconventional p-wave\nsuperconductivity in Josephson junctions based on topological insulators (TIs).\nFor that purpose we propose to use superconducting Klein tunneling, i.e. the\nreflectionless passage of Cooper pairs through a potential barrier in a gated\nballistic junction. This phenomenon occurs due to the fact that the\nsupercurrent is carried by helical Andreev bound states (ABSs) characterized by\nspin-momentum locking similar to the normal-state carriers. We derive the\nspectrum of the helical ABSs and the corresponding Josephson current for a\njunction made on the surface of a three-dimensional TI. The superconducting\nKlein tunneling is predicted to yield a non-sinusoidal current-phase relation\nand an anomalous critical current $I_c$ that does not vanish with increasing\nbarrier strength. We also analyze the dependence of the I_cR_n product (where\nR_n is the normal-state junction resistance) on the microscopic parameters of\nthe superconductor/TI interface, which leads to lower I_cR_n values than\nexpected from previous models of the proximity-effect Josephson junctions."
    },
    {
        "anchor": "Germanium quantum well Josephson field effect transistors and\n  interferometers: Hybrid superconductor-semiconductor structures attract increasing attention\nowing to a variety of potential applications in quantum computing devices. They\ncan serve to the realization of topological superconducting systems, as well as\ngate-tunable superconducting quantum bits. Here we combine a SiGe/Ge/SiGe\nquantum-well heterostructure hosting high-mobility two-dimensional holes and\naluminum superconducting leads to realize prototypical hybrid devices, such as\nJosephson field-effect transistors (JoFETs) and superconducting quantum\ninterference devices (SQUIDs). We observe gate-controlled supercurrent\ntransport with Ge channels as long as one micrometer and estimate the induced\nsuperconducting gap from tunnel spectroscopy measurements in superconducting\npoint-contact devices. Transmission electron microscopy reveals the diffusion\nof Ge into the aluminum contacts, whereas no aluminum is detected in the Ge\nchannel.",
        "positive": "Strongly temperature dependent resistance of meander-patterned graphene: We have studied the electronic properties of epitaxial graphene devices\npatterned in a meander shape with the length up to a few centimeters and the\nwidth of few tens of microns. These samples show a pronounced dependence of the\nresistance on temperature. Accurate comparison with theory shows that this\ntemperature dependence originates from the weak localization effect observed\nover a broad temperature range from 1.5 K up to 77 K. The comparison allows us\nto estimate the characteristic times related to quantum interference. In\naddition, a large resistance enhancement with temperature is observed at the\nquantum Hall regime near the filling factor of 2. Record high resistance and\nits strong temperature dependence are favorable for the construction of\nbolometric photodetectors."
    },
    {
        "anchor": "Learning and Controlling Silicon Dopant Transitions in Graphene using\n  Scanning Transmission Electron Microscopy: We introduce a machine learning approach to determine the transition dynamics\nof silicon atoms on a single layer of carbon atoms, when stimulated by the\nelectron beam of a scanning transmission electron microscope (STEM). Our method\nis data-centric, leveraging data collected on a STEM. The data samples are\nprocessed and filtered to produce symbolic representations, which we use to\ntrain a neural network to predict transition probabilities. These learned\ntransition dynamics are then leveraged to guide a single silicon atom\nthroughout the lattice to pre-determined target destinations. We present\nempirical analyses that demonstrate the efficacy and generality of our\napproach.",
        "positive": "Theory of the in-plane photoelectric effect in two-dimensional electron\n  systems: A new photoelectric phenomenon, the in-plane photoelectric (IPPE) effect, has\nbeen recently discovered at terahertz (THz) frequencies in a\nGaAs/Al$_x$Ga$_{1-x}$As heterostructure with a two-dimensional (2D) electron\ngas (W. Michailow et al., Sci. Adv. \\textbf{8}, eabi8398 (2022)). In contrast\nto the conventional PE phenomena, the IPPE effect is observed at normal\nincidence of radiation, the height of the in-plane potential step, which\nelectrons overcome after absorption of a THz photon, is electrically tunable by\ngate voltages, and the effect is maximal at a negative electron ``work\nfunction'', when the Fermi energy lies above the potential barrier. Based on\nthe discovered phenomenon, efficient detection of THz radiation has been\ndemonstrated. In this work we present a detailed theory of the IPPE effect\nproviding analytical results for the THz wave generated photocurrent, the\nquantum efficiency, and the internal responsivity of the detector, in\ndependence on the frequency, the gate voltages, and the geometrical parameters\nof the detector. The calculations are performed for macroscopically wide\nsamples at zero temperature. Results of the theory are applicable to any\nsemiconductor systems with 2D electron gases, including III-V structures,\nsilicon-based field effect transistors, and the novel 2D layered,\ngraphene-related materials."
    },
    {
        "anchor": "Electron Interactions in Bilayer Graphene: Marginal Fermi Liquid\n  Behaviour and Zero Bias Anomaly: We analyze the many-body properties of bilayer graphene (BLG) at charge\nneutrality, governed by long range interactions between electrons. Perturbation\ntheory in a large number of flavors is used in which the interactions are\ndescribed within a random phase approximation, taking account of dynamical\nscreening effect. Crucially, the dynamically screened interaction retains some\nlong range character, resulting in $\\log^2$ renormalization of key quantities.\nWe carry out the perturbative renormalization group calculations to one loop\norder, and find that BLG behaves to leading order as a marginal Fermi liquid.\nInteractions produce a log squared renormalization of the quasiparticle residue\nand the interaction vertex function, while all other quantities renormalize\nonly logarithmically. We solve the RG flow equation for the Green function with\nlogarithmic accuracy, and find that the quasiparticle residue flows to zero\nunder RG. At the same time, the gauge invariant quantities, such as the\ncompressibility, remain finite to $\\log^2$ order, with subleading logarithmic\ncorrections. The key experimental signature of this marginal Fermi liquid\nbehavior is a strong suppression of the tunneling density of states, which\nmanifests itself as a zero bias anomaly in tunneling experiments in a regime\nwhere the compressibility is essentially unchanged from the non-interacting\nvalue.",
        "positive": "Comment on: \"Luminescence spectra of quantum dots in microcavities.\": In this comment we show that there is a direct connection between coherent\nexchange of energy among light and matter and the emission spectrum of a\nmicrocavity quantum dot system as modeled in Phys. Rev. B 79, 235325 (2009)\n[arXiv:0807.3194] by F. P. Laussy, E. del Valle, and C. Tejedor. To do so, we\nshow that in their model the necessary and sufficient conditions for having\neigenvalues with non-zero imaginary parts in the propagator of the bare mode\npopulations, are the same as for having strong coupling in the emission\nspectrum. This amounts to saying that, whenever there is strong coupling there\nwill be oscillating frequencies in the dynamics of the populations. These\nconditions are valid both for the case where matter is treated as bosonic or\nfermionic, in the spontaneous emission case."
    },
    {
        "anchor": "Strong Light-Matter Coupling in Carbon Nanotubes as a Route to Exciton\n  Brightening: We show that strong light-matter coupling can be used to overcome a long\nstanding problem that has prevented efficient optical emission from carbon\nnanotubes. The luminescence from the nominally bright exciton states of carbon\nnanotubes is quenched due to the fast nonradiative scattering to the dark\nexciton state having a lower energy. We present a theoretical analysis to show\nthat by placing carbon nanotubes in an optical microcavity the bright exctonic\nstate may be split into two hybrid exciton-polariton states, while the dark\nstate remains unaltered. For sufficiently strong coupling between the bright\nexciton and the cavity, we show that the energy of the lower polariton may be\npushed below that of the dark exciton. This overturning of the relative\nenergies of the bright and dark excitons prevents the dark exciton from\nquenching the emission. Our resutls pave the way for a new approach to\nband-engineering the properties of the nanoscale optoelectronic devices.",
        "positive": "Adiabatic Cooling with Non-Abelian Anyons: We show in this Letter that the ground state degeneracy associated with the\npresence of non-Abelian anyons can be probed by using an adiabatic cooling\nprocess based on the non-Abelian entropy. In particular, we show that when the\nnumber of such anyons is increased adiabatically at sufficiently low\ntemperatures, the non-Abelian liquid undergoes cooling, whereas heating occurs\nin the Abelian case. Estimates are provided for the cooling power produced by\nthe non-Abelian anyon refrigerator, and its implementation in non-Abelian\nfractional quantum Hall liquids is discussed."
    },
    {
        "anchor": "Quantum Hall Phase Diagram of Second Landau-level Half-filled Bilayers:\n  Abelian versus Non-Abelian States: The quantum Hall phase diagram of the half-filled bilayer system in the\nsecond Landau level is studied as a function of tunneling and layer separation\nusing exact diagonalization. We make the striking prediction that bilayer\nstructures would manifest two distinct branches of incompressible fractional\nquantum Hall effect (FQHE) corresponding to the Abelian 331 state (at moderate\nto low tunneling and large layer separation) and the non-Abelian Pfaffian state\n(at large tunneling and small layer separation). The observation of these two\nFQHE branches and the quantum phase transition between them will be compelling\nevidence supporting the existence of the non-Abelian Pfaffian state in the\nsecond Landau level.",
        "positive": "Selectively addressing plasmonic modes and excitonic states in a\n  nanocavity hosting a quantum emitter: Understanding and controlling the interaction between the excitonic states of\na quantum emitter and the plasmonic modes of a nanocavity is one of the most\nrelevant current scientific challenges, key for the development of many\napplications, from quantum information processing devices to polaritonic\ncatalysts. In this paper we demonstrate that the tunnel electroluminescence of\nC60 nanocrystals enclosed in the plasmonic nanocavity between a metallic\nsurface and the tip of a Scanning Tunnelling Microscope, and isolated from the\nmetal surface by a thin NaCl film, can be switched from a broad emission\nspectrum, revealing the plasmonic modes of the cavity, to a narrow band\nemission, displaying only the excitonic states of the C60 molecules by changing\nthe bias voltage applied to the junction. Plasmonic emission is found in the\nsame voltage region in which the rate of inelastic tunnel transitions is large\nand, thus, vanishes for large voltages. Excitonic emission, on the other hand,\ndominates the spectra in the high-voltage region in which the inelastic rate is\nlow, demonstrating that the excitons cannot be created by an inelastic tunnel\nprocess. These results point towards new possible mechanisms to explain the\ntunnel electroluminescence of quantum emitters and offer new avenues to develop\nelectrically tuneable nanoscale light sources."
    },
    {
        "anchor": "Thermal transistor and thermometer based on Coulomb-coupled conductors: We study a three-terminal setup consisting of a single-level quantum dot\ncapacitively coupled to a quantum point contact. The point contact connects to\na source and drain reservoirs while the quantum dot is coupled to a single base\nreservoir. This setup has been used to implement a noninvasive, nanoscale\nthermometer for the bath reservoir by detecting the current in the quantum\npoint contact. Here, we demonstrate that the device can also be operated as a\nthermal transistor where the average (charge and heat) current through the\nquantum point contact is controlled via the temperature of the base reservoir.\nWe characterize the performances of this device both as a transistor and a\nthermometer, and derive the operating condition maximizing their respective\nsensitivities. The present analysis is useful for the control of charge and\nheat flow and high precision thermometry at the nanoscale.",
        "positive": "Magnetic properties of Fe3O4 nanoparticles coated with oleic and\n  dodecanoic acids: Magnetic nanoparticles (NP) of magnetite (Fe3O4) coated with oleic acid (OA)\nand dodecanoic acid (DA) were synthesized and investigated through Transmission\nElectron Microscopy (TEM),magnetization M, and ac magnetic susceptibility\nmeasurements. The OA coated samples were produced with different magnetic\nconcentrations (78, 76, and 65%) and the DA sample with 63% of Fe3O4. Images\nfrom TEM indicate that the NP have a nearly spherical geometry and mean\ndiameter ~ 5.5 nm. Magnetization measurements, performed in zero field cooled\n(ZFC) and field cooled (FC) processes under different external magnetic fields\nH, exhibited a maximum at a given temperature TB in the ZFC curves, which\ndepends on the NP coating (OA or DA), magnetite concentration, and H. The\ntemperature TB decreases monotonically with increasing H and, for a given H,\nthe increase in the magnetite concentration results in an increase of TB. The\nobserved behavior is related to the dipolar interaction (DI) between NP which\nseems to be an important mechanism in all samples studied. This is supported by\nthe results of the ac magnetic susceptibility Xac measurements, where the\ntemperature in which X' peaks for different frequencies follows the\nVogel-Fulcher model, a feature commonly found in systems with dipolar\ninteractions. Curves of H vs. TB/TB(H=0) for samples with different coatings\nand magnetite concentrations collapse into a universal curve, indicating that\nthe qualitative magnetic behavior of the samples may be described by the NP\nthemselves, instead of the coating or the strength of the dipolar interaction.\nBelow TB, M vs. H curves show a coercive field (HC) that increases\nmonotonically with decreasing temperature. The saturation magnetization (MS)\nfollows the Bloch's law and values of MS at room temperature as high as 78\nemu/g were estimated, a result corresponding to ~80% of the bulk value. The\noverlap of M/MS vs. H/T curves for a given sample and the low HC at high\ntemperatures suggest superparamagnetic behavior in all samples studied. The\noverlap of M/MS vs. H curves at constant temperature for different samples\nindicates that the NP magnetization behavior is preserved, independently of the\ncoating and magnetite concentration."
    },
    {
        "anchor": "Edge Spin Current and Spin Polarization in Quantum Hall Regime: We study the edge spin current and spin polarization in a two-dimensional\nelectron gas with spin-orbit coupling in the presence of a perpendicular\nmagnetic field. The edge effect removes the degeneracy of Landau levels due to\nthe competition between the Rashba coupling and the Zeeman splitting, which\nexists in the bulk. Large spin edge current and non-linear response to an\nelectric field are found when the two levels are degenerated in the bulk. It is\nfound that he spin current is proportional to spin polarization along the\ny-direction in an finite magnetic field, which provides a way to extract the\nspin current in the system.",
        "positive": "A Tunable Phonon-Exciton Fano System in Bilayer Graphene: Interference between different possible paths lies at the heart of quantum\nphysics. Such interference between coupled discrete and continuum states of a\nsystem can profoundly change its interaction with light as seen in Fano\nresonance. Here we present a unique many-body Fano system composed of a\ndiscrete phonon vibration and continuous electron-hole pair transitions in\nbilayer graphene. Mediated by the electron-phonon interactions, the excited\nstate is described by new quanta of elementary excitations of hybrid\nphonon-exciton nature. Infrared absorption of the hybrid states exhibit\ncharacteristic Fano lineshapes with parameters renormalized by many-body\ninteractions. Remarkably, the Fano resonance in bilayer graphene is\ncontinuously tunable through electrical gating. Further control of the\nphonon-exciton coupling may be achieved with an optical field exploiting the\nexcited state infrared activity. This tunable phonon-exciton system also offers\nthe intriguing possibility of a 'phonon laser' with stimulated phonon\namplification generated by population inversion of band-edge electrons."
    },
    {
        "anchor": "Graphenic Carbon-Silicon Contacts for Reliability Improvement of\n  Metal-Silicon Junctions: Contact resistance and thermal degradation of metal-silicon contacts are\nchallenges in nanoscale CMOS as well as in power device applications. Titanium\nsilicide (TiSi) contacts are commonly used metal-silicon contacts, but are\nknown to diffuse into the active region under high current stress. In this\npaper we show that a graphenic carbon (C) contact deposited on n-type silicon\n(C-Si) by CVD, has the same low Schottky barrier height of 0.45 eV as TiSi, but\na much improved reliability against high current stress. The C-Si contact is\nover 100 million times more stable against high current stress pulses than the\nconventionally used TiSi junction. The C-Si contact properties even show\npromise to establish an ultra-low, high temperature stable contact resistance.\nThe finding has important consequences for the enhancement of reliability in\npower devices as well as in Schottky-diodes and electrical contacts to silicon\nin general.",
        "positive": "Nonlinear optical spectroscopy of indirect excitons in biased coupled\n  quantum wells: Indirect excitons in coupled quantum wells are long-living quasi-particles,\nexplored in the studies of collective quantum states. We demonstrate, that\ndespite the extremely low oscillator strength, their spin and population\ndynamics can by addressed by time-resolved pump-probe spectroscopy. Our\nexperiments make it possible to unravel and compare spin dynamics of direct\nexcitons, indirect excitons and residual free electrons in coupled quantum\nwells. Measured spin relaxation time of indirect excitons exceeds not only one\nof direct excitons, but also one of free electrons by two orders of magnitude."
    },
    {
        "anchor": "Optical Hall effect in strained graphene: When passing an optical medium in the presence of a magnetic field, the\npolarization of light can be rotated either when reflected at the surface (Kerr\neffect) or when transmitted through the material (Faraday rotation). This\nphenomenon is a direct consequence of the optical Hall effect arising from the\nlight-charge carrier interaction in solid state systems subjected to an\nexternal magnetic field, in analogy with the conventional Hall effect. The\noptical Hall effect has been explored in many thin films and also more recently\nin 2D layered materials. Here, an alternative approach based on strain\nengineering is proposed to achieve an optical Hall conductivity in graphene\nwithout magnetic field. Indeed, strain induces lattice symmetry breaking and\nhence can result in a finite optical Hall conductivity. First-principles\ncalculations also predict this strain-induced optical Hall effect in other 2D\nmaterials. Combining with the possibility of tuning the light energy and\npolarization, the strain amplitude and direction, and the nature of the optical\nmedium, large ranges of positive and negative optical Hall conductivities are\npredicted, thus opening the way to use these atomistic thin materials in novel\nspecific opto-electro-mechanical devices.",
        "positive": "Getting information from the mixed electrical-heat noise: We give a classification of the different types of noise in a quantum dot,\nfor variable temperature, voltage and frequency. It allows us first to show\nwhich kind of information can be extracted from the electrical noise, such as\nthe ac-conductance or the Fano factor. And next, to classify the mixed\nelectrical-heat noise, and to identify in which regimes information on the\nSeebeck coefficient, on the thermoelectric figure of merit, or on the\nthermoelectric efficiency can be obtained."
    },
    {
        "anchor": "Electron backscattering in a cavity: ballistic and coherent effects: Numerous experimental and theoretical studies have focused on low-dimensional\nsystems locally perturbed by the biased tip of a scanning force microscope. In\nall cases either open or closed weakly gate-tunable nanostructures have been\ninvestigated, such as quantum point contacts, open or closed quantum dots, etc.\nWe study the behaviour of the conductance of a quantum point contact with a\ngradually forming adjacent cavity in series under the influence of a scanning\ngate. Here, an initially open quantum point contact system gradually turns into\na closed cavity system. We observe branches and interference fringes known from\nquantum point contacts coexisting with irregular conductance fluctuations.\nUnlike the branches, the fluctuations cover the entire area of the cavity. In\ncontrast to previous studies, we observe and investigate branches under the\ninfluence of the confining stadium potential, which is gradually built up. We\nfind that the branches exist only in the area surrounded by cavity top gates.\nAs the stadium shrinks, regular fringes originate from tip-induced\nconstrictions leading to quantized conduction. In addition, we observe arc-like\nareas reminiscent of classical electron trajectories in a chaotic cavity. We\nalso argue that electrons emanating from the quantum point contact spread out\nlike a fan leaving branch-like regions of enhanced backscattering.",
        "positive": "Self-consistent simulation of quantum wires defined by local oxidation\n  of Ga[Al]As heterostructures: We calculate the electronic width of quantum wires as a function of their\nlithographic width in analogy to experiments performed on nanostructures\ndefined by local oxidation of Ga[Al]As heterostructures. Two--dimensional\nsimulations of two parallel oxide lines on top of a Ga[Al]As heterostructure\ndefining a quantum wire are carried out in the framework of Density Functional\nTheory in the Local Density Approximation and are found to be in agreement with\nmeasurements. Quantitative assessment of the influence of various experimental\nuncertainties is given. The most influential parameter turns out to be the\noxide line depth, followed by its exact shape and the effect of background\ndoping (in decreasing order)."
    },
    {
        "anchor": "Second Generation of Composite Fermions and the Self-Similarity of the\n  Fractional Quantum Hall Effect: A recently developed model of interacting composite fermions, is used to\ninvestigate different composite-fermion phases. Their interaction potential\nallows for the formation of both solid and new quantum-liquid phases, which are\ninterpreted in terms of second-generation composite fermions and which may be\nresponsible for the fractional quantum Hall states observed at unusual filling\nfactors, such as nu=4/11. Projection of the composite-fermion dynamics to a\nsingle level, involved in the derivation of the Hamiltonian of interacting\ncomposite fermions, reveals the underlying self-similarity of the model.",
        "positive": "Enhancing Near-Field Heat Transfer in Composite Media: Effects of the\n  Percolation Transition: We investigate the near-field heat transfer between a semi-infinite medium\nand a nanoparticle made of composite materials. We show that, in the effective\nmedium approximation, the heat transfer can be greatly enhanced by considering\ncomposite media, being maximal at the percolation transition. Specifically, for\ntitanium inclusions embedded in a polystyrene sphere, this enhancement can be\nup to thirty times larger than in the case of the corresponding homogeneous\ntitanium sphere. We demonstrate that our findings are robust against material\nlosses, to changes in the shape of inclusions and materials, and apply for\ndifferent effective medium theories. These results suggest the use of composite\nmedia as a new, versatile material platform to enhance, optimize, and tailor\nnear-field heat transfer in nanostructures."
    },
    {
        "anchor": "Reduction of radiative lifetime and slow-timescale spectral diffusion in\n  InGaN polarized single-photon sources: Non-polar (11-20) a-plane quantum dots (QDs) are strong candidates for both >\n200 K on-chip ultrafast polarized single-photon generation and the\ninvestigation of high temperature semiconductor QD photophysics. In this work,\nwe report progress in the growth of a-plane InGaN QDs with a\nquasi-two-temperature method, which produces smooth epilayers and significantly\nreduced carrier trapping sites in the proximity of the QDs. Optical\ncharacterization has confirmed the ability of such QDs to emit polarized single\nphotons and we have recorded a ~ 45% shorter average radiative lifetime and 65%\nreduction in the slow-timescale spectral diffusion compared to previous QDs.\nThis growth method is an important development of the non-polar a-plane InGaN\nplatform, opening up more possibilities in single-photon, lasing, and\nfundamental investigations.",
        "positive": "Experimental verification of the rotational sense and type of chiral\n  spin spiral structure by spin-polarized scanning tunneling microscopy: We report on experimental verification of the rotational sense and type of\nhomogeneous chiral spin spiral order in a Mn monolayer on a W(110) substrate\nusing spin-polarized scanning tunneling microscopy. We found that the magnetic\ncontrast due to the spin spiral order almost vanishes with a magnetic tip\nmagnetized normal to the (001) plane, indicating that the spin spiral rotates\nin the plane. From a shift in the most-contrasted sites by changing the tip\nmagnetization direction within the rotating plane, we reveal that the\nrotational sense is left-handed, consistent with the previous results predicted\nby first-principle calculations. By comparing the current system with a chiral\nmagnetic domain wall in Fe double layers on the same substrate, we found that\nthe polarity of the Dzyaloshinskii--Moriya interaction, the driving force of\nthose chiral magnets, is dominantly determined by the choice of the substrate\nrather than the overlayer."
    },
    {
        "anchor": "Bound states of charges on top of graphene in magnetic field: We show theoretically that in the external magnetic field like charges on top\nof graphene monolayer may be mutually attracted to form macro-molecules. For\nthis to happen graphene needs to be in Quantum Hall plateau state with local\nchemical potential being between the Landau levels. Graphene electron(s) gets\nlocalized in the middle between charges and provides overscreening of Coulomb\nrepulsion between the charges. The size of the resulting macro-molecules is of\nthe order of the magnetic length ($\\sim 10$ nm for magnetic field 10 T). The\npossible stable macro-molecules that unit charges can form on graphene in\nmagnetic field are classified. The binding survives significant temperatures,\nexceeding mobility barriers for many ionically bond impurities. The influence\nof possible lattice-scale effects of valley-mixing are discussed.\n  Tuning the doping of graphene or the magnetic field, the binding of\nimpurities can be turned on and off and the macro-molecule size may be tuned.\nThis opens the perspective to nanoscopic manipulation of ions on graphene by\nusing magnetic field and gating.",
        "positive": "Rapidly rotating Bose-Einstein condensates in an anharmonic confinement: We examine a rapidly rotating Bose-Einstein condensate in an anharmonic\nconfinement and find that many properties such as the critical rotating\nfrequency and phase diagram are quite different from those in a harmonic trap.\nWe investigate the phase transitions by means of average-vortex-approximation.\nWe find that the vortex lattice consists of a vortex array with a hole in the\ncenter of the cloud as the rotating frequency $\\Omega$ increases and the vortex\nbecomes invisible when $\\Omega$ reaches some value."
    },
    {
        "anchor": "How Thermal Effect Regulates Cyclic Voltammetry of Supercapacitors: Cyclic voltammetry (CV) is a powerful technique for characterizing\nelectrochemical properties of electrochemical devices. During\ncharging-discharging cycles, thermal effect has profound impact on its\nperformance, but existing theoretical models cannot clarify such intrinsic\nmechanism and often give poor prediction. Herein, we propose an interfacial\nmodel for the electro-thermal coupling, based on fundamentals in\nnon-equilibrium statistical mechanics. By incorporating molecular interactions,\nour model shows a quantitative agreement with experimental measurements. The\nintegral capacitance shows a first enhanced then decayed trend against the\napplied heat bath temperature. Such a relation is attributed to the competition\nbetween electrical attraction and Born repulsion via dielectric inhomogeneity,\nwhich is rarely understood in previous models. In addition, as evidenced in\nrecent experimental CV tests, our model predicts the non-monotonic dependence\nof the capacitance on the bulk electrolyte density, further demonstrating its\nhigh accuracy. This work demonstrates a potential pathway towards\nnext-generation thermal regulation of electrochemical devices.",
        "positive": "Magnetic focusing in normal-superconductor hybrid systems: a\n  semiclassical analysis: We study a transverse electron-hole focusing effect in a\nnormal-superconductor system. The spectrum of the quasiparticles is calculated\nboth quantum mechanically and in semiclassical approximation, showing an\nexcellent agreement. A semiclassical conductance formula is derived which takes\ninto account the effect of electron-like as well as hole-like quasiparticles.\nAt low magnetic field the semiclassical conductance shows characteristic\noscillations due to the Andreev reflection, while at higher fields it goes to\nzero. These findigs are in line with the results of previous quantum\ncalculations and with the expectations based on the classical dynamics of the\nquasiparticles."
    },
    {
        "anchor": "Quantizing momentum transport in bilayer graphene: The momentum transport in ultraclean bilayer graphene is characterized by the\nviscous transport. In quantizing magnetic field the momentum current passes\nthrough the guiding centers of cyclotron orbits. In this study we derive the\nquantized Hall viscosity of bilayer graphene that is the next topological\nfeature after the quantum Hall effect. This can be detected in the non-local\nmagnetoresistivity measurements that varies with the quantized steps of\nmagnetoresistivity.",
        "positive": "Folding Catastrophes due to Viscosity in Multiferroic Domains:\n  Implications for Room-Temperature Multiferroic Switching: Unusual domains with curved walls and failure to satisfy the\nLandau-Lifshitz-Kittel Law are modeled as folding catastrophes (saddle-node\nbifurcations). This description of ballistic motion in a viscous medium is\nbased upon early work by Dawber et al., Appl. Phys. Lett. 82, 436 (2003). It\nsuggests that ferroelectric films can exhibit folds or vortex patterns but not\nboth."
    },
    {
        "anchor": "Chern pump: a bridge between integer quantum Hall effect and quantum\n  spin Hall effect: We propose a electron-pumping mechanism called Chern pump to explain the\ninteger quantum Hall effect(IQHE) in the Chern insulator. By using the parallel\ntransport gauge in the hybrid Wannier representation we establish the bulk and\nedge states correspondence in the Chern insulator. The same correspondence can\nalso be established in two dimensional(2D) topological insulator(TI). So we can\nconsider 2D TI as two time reversal(TR) related CIs put together. The quantum\nspin Hall effect(QSHE) can be viewed as two TR related Chern pumps pumping\nelectrons to opposite directions. Compared with the Z2 spin pump, the two Chern\npumps explanation of QSHE is inherently 2D and predict that the QSHE can be\ndetected in isolated device, thus make the QSHE directly measurable.",
        "positive": "Quantum Computation with Aharonov-Bohm Qubits: We analyze the posibility of employing the mesoscopic-nanoscopic ring of a\nnormal metal in a doubly degenerate persistent current state with a third\nauxihilary level and in the presence of the Aharonov-Bohm flux equal to the\nhalf of the normal flux quantum $\\hbar c/e$ as a qubit. The auxiliary level can\nbe effectively used for all fundamental quantum logic gate (qu-gate) operations\nwhich includes the initialization, phase rotation, bit flip and the Hadamard\ntransformation as well as the double-qubit controlled operations (conditional\nbit flip). We suggest a tentative realization of the mechanism as either the\nmesoscopic structure of three quantum dots coherently coupled by mesoscopic\ntunnelling in crossed magnetic and electric fields, or as a nanoscopic\nstructure of triple anionic vacancy (similar to $F_3$ centers in alkali\nhalides) with one trapped electron in one spin projection state."
    },
    {
        "anchor": "Generalized correction to embedded-atom potentials for modeling\n  equilibrium and non-equilibrium properties of metals: A modification of an embedded-atom method (EAM)-type potential is proposed\nfor a quantitative description of equilibrium and non-equilibrium properties of\nmetal systems within the molecular-dynamics framework. The modification\ngeneralizes the previously developed linear correction to EAM-type potentials\n[Sushko et al., J. Phys.: Condens. Matter \\textbf{28}, 145201 (2016)] and\nasymptotically approaches zero at large interatomic distances. A general\nprocedure for constructing this modification is outlined and its relation to\nthe linear correction is elaborated. To benchmark this procedure, we examine\nthe melting phase transition and several equilibrium properties of nanosystems\nmade of silver, gold, and titanium. The simulations performed with the modified\npotential predict higher bulk melting temperatures of the metals and agree\nbetter with experimental values as compared to the original EAM-type potential.\nOur results show that the modification works well for metals with both cubic\nand hexagonal crystalline lattices. The Gupta potential is chosen as an\nillustrative case study but the modification proposed is general and can be\napplied to other widely-used potentials of the EAM type.",
        "positive": "Tunable electron-phonon interactions in long-period superlattices: The efficiency of optical emitters can be dramatically enhanced by reducing\nthe effective mode volume (the Purcell effect). Here we predict an analogous\nenhancement for electron-phonon (el-ph) scattering, achieved by compressing the\nelectronic Wannier orbitals. Reshaping of Wannier orbitals is a prominent\neffect in graphene moir\\'e superlattices (SLs) where the orbitals are tunable\nby the twist angle. A reduction of the orbital effective volume leads to an\nenhancement in the effective el-ph coupling strength, yielding the values\nconsiderably bigger than those known for pristine monolayer graphene. The\nenhanced coupling boosts the el-ph scattering rates, pushing them above the\nvalues predicted from the enhanced spectral density of electronic excitations.\nThe enhanced phonon emission and scattering rates are manifest in the\nobservables such as electron-lattice cooling and the linear-$T$ resistivity,\nboth of which are directly tunable by the moir\\'e twist angle."
    },
    {
        "anchor": "Few Layer HfS2 FET: 2D materials are expected to be favorable channel materials for field-effect\ntransistor (FET) with extremely short channel length because of their superior\nimmunity to short-channel effects (SCE). Graphene, which is the most famous 2D\nmaterial, has no bandgap without additional techniques and this property is\nmajor hindrance in reducing the drain leakage. Therefore, 2D materials with\nfinite band gap, such as transition metal dichalcogenides (TMDs, e.g. MoS2\nWSe2) or phosphorene, are required for the low power consumption FETs. Hafnium\ndisulfide (HfS2) is a novel TMD, which has not been investigated as channel\nmaterial. We focused on its potential for well-balanced mobility and bandgap\nproperties. The higher electron affinity of Hf dichalcogenides compared with Mo\nor W chalcogenides facilitates the formation of low resistance contact and\nstaggered heterojunction with other 2D materials. Here we demonstrate the first\nfew layer HfS2 FET with robust current saturation and high current on/off ratio\nof more than 10^4.",
        "positive": "Unveiling Topological Modes on Curved Surfaces: In this paper, we investigate topological modes of different physical systems\ndefined on arbitrary two-dimensional curved surfaces. We consider the shallow\nwater equations, inhomogeneous Maxwell's equations, Jackiw-Rebbi model and show\nhow the topological protection mechanism responses to the presence of curvature\nin different situations. We show the existence of a line gap in the considered\nmodels and study the condition on the curve which can host topological modes."
    },
    {
        "anchor": "Particle number scaling for diffusion-induced dissipation in graphene\n  and carbon nanotube nanomechanical resonators: When a contaminant diffuses on the surface of a nanomechanical resonator, the\nmotions of the two become correlated. Despite being a high-order effect in the\nresonator-particle coupling, such correlations affect the system dynamics by\ninducing dissipation of the resonator energy. Here, we consider this\ndiffusion-induced dissipation in the cases of multiple particles adsorbed on\ncarbon nanotube and graphene resonators. By solving the stochastic equations of\nmotion, we simulate the ringdown of the resonator, in order to determine the\nresonator energy decay rate. We find two different scalings with the number of\nadsorbed particles $K$ and particle mass $m$. In the regime where the\nadsorbates are inertially trapped at an antinode of vibration, the dissipation\nrate $\\Gamma$ scales with the total adsorbed mass $\\Gamma\\propto Km$. In\ncontrast, in the regime where particles diffuse freely over the resonator, the\ndissipation rate scales as the product of the total adsorbed mass and the\nindividual particle mass: $\\Gamma\\propto Km^2$.",
        "positive": "Synthesis and electrical properties of fullerene-based molecular\n  junctions on silicon substrate: We report the synthesis and the electrical properties of fullerene-based\nmolecular junctions on silicon substrate in which the highly \\pi-conjugated\nmolecule C60 (\\pi quantum well) is isolated from the electrodes by alkyl chains\n(\\sigma tunnel barriers). Initially, the Si/SiO2/\\sigmaC60 architecture was\nprepared either by sequential synthesis (3 different routes) or by direct\ngrafting of the presynthesized C60-\\sigma-Si(OEt)3 molecule. We described the\nchemical synthesis of these routes and the physico-chemical properties of the\nmolecular monolayers. Then, the second \\sigma tunnel barrier was added on the\nSi/SiO2/\\sigma C60 junction by applying a hanging mercury drop electrode\nthiolated with an alkanethiol monolayer. We compared the electronic transport\nproperties of the Si/SiO2/\\sigma C60//Hg and Si/SiO2/\\sigma C60//\\sigmaHg\nmolecular junctions, and we demonstrated by transition voltage spectroscopy\nthat the fullerene LUMO - metal Fermi energy offset can be tailored from ~ 0.2\neV to ~ 1 eV by changing the length of the alkyl chain between the C60 core and\nthe Hg metal electrode (i. e. from direct C60//Hg contact to 14 carbon atoms\ntunnel barrier)."
    },
    {
        "anchor": "Josephson Field-Effect Transistors Based on All-Metallic Al/Cu/Al\n  Proximity Nanojunctions: We demonstrate the first \\textit{all-metallic} mesoscopic\nsuperconductor-normal metal-superconductor (SNS) field-effect controlled\nJosephson transistors (SNS-FETs) and show their full characterization from the\ncritical temperature $T_c$ down to 50 mK in the presence of both electric and\nmagnetic field. The ability of a static electric field -applied by mean of a\nlateral gate electrode- to suppress the critical current $I_s$ in a\nproximity-induced superconductor is proven for both positive and negative gate\nvoltage values. $I_s$ suppression reached typically about one third of its\ninitial value, saturating at high gate voltages. The transconductance of our\nSNS-FETs obtains values as high as 100 nA/V at 100 mK. On the fundamental\nphysics side, our results suggest that the mechanism at the basis of the\nobserved phenomenon is quite general and does not rely on the existence of a\ntrue pairing potential, but rather the presence of superconducting correlations\nis enough for the effect to occur. On the technological side, our findings\nwiden the family of materials available for the implementation of all-metallic\nfield-effect transistors to \\textit{synthetic} proximity-induced\nsuperconductors.",
        "positive": "Shuttling of Spin Polarized Electrons in Molecular Transistors: Shuttling of electrons in single-molecule transistors with magnetic leads in\nthe presence of an external magnetic field is considered theoretically. For a\ncurrent of partially spin-polarized electrons a shuttle instability is\npredicted to occur for a finite interval of external magnetic field strengths.\nThe lower critical magnetic field is determined by the degree of spin\npolarization and it vanishes as the spin polarization approaches 100%. The\nfeasibility of detecting magnetic shuttling in a $C_{60}$-based molecular\ntransistor with magnetic (Ni) electrodes is discussed [A.~N.~Pasupathy et al.,\nScience 306, 86 (2004)]."
    },
    {
        "anchor": "Shot Noise in Schottky's Vacuum Tube: In these notes we discuss the origin of shot noise ('Schroteffekt') of vacuum\ntubes in detail. It will be shown that shot noise observed in vacuum tubes and\nfirst described by W. Schottky in 1918 is a purely classical phenomenon. This\nis in pronounced contrast to shot noise investigated in mesoscopic conductors\nwhich is due to quantum mechanical diffraction of electron waves.",
        "positive": "Structural, magnetic, dielectric and mechanical properties of\n  (Ba,Sr)MnO$_3$ ceramics: Ceramic samples, produced by conventional sintering method in ambient air,\n6H-SrMnO$_3$(6H-SMO), 15R-BaMnO$_3$(15R-BMO),\n4H-Ba$_{0.5}$Sr$_{0.5}$MnO$_3$(4H-BSMO) were studied. In the XRD measurements\nfor SMO the new anomalies of the lattice parameters at 600-800 K range and the\nincreasing of thermal expansion coefficients with a clear maximum in a vicinity\nat 670 K were detected. The N$\\acute{e}$el phase transition for BSMO was\nobserved at $T_N$=250 K in magnetic measurements and its trace was detected in\ndielectric, FTIR, DSC, and DMA experiments. The enthalpy and entropy changes of\nthe phase transition for BSMO at $T_N$ were determined as 17.5 J/mol and 70\nmJ/K mol, respectively. The activation energy values and relaxation times\ncharacteristic for relaxation processes were determined from the Arrhenius law.\nResults of ab initio simulations showed that the contribution of the exchange\ncorrelation energy to the total energy is about 30%."
    },
    {
        "anchor": "From materials to systems: a multiscale analysis of nanomagnetic\n  switching: With the increasing demand for low-power electronics, nanomagnetic devices\nhave emerged as strong potential candidates to complement present day\ntransistor technology. A variety of novel switching effects such as spin torque\nand giant spin Hall offer scalable ways to manipulate nano-sized magnets.\nHowever, the low intrinsic energy cost of switching spins is often compromised\nby the energy consumed in the overhead circuitry in creating the necessary\nswitching fields. Scaling brings in added concerns such as the ability to\ndistinguish states (readability) and to write information without spontaneous\nbackflips (reliability). A viable device must ultimately navigate a complex\nmulti-dimensional material and design space defined by volume, energy budget,\nspeed and a target read-write-retention error. In this paper, we review the\nmajor challenges facing nanomagnetic devices and present a multi-scale\ncomputational framework to explore possible innovations at different levels\n(material, device, or circuit), along with a holistic understanding of their\noverall energy-delay-reliability tradeoff.",
        "positive": "Strain-induced nonlinear spin Hall effect in topological Dirac semimetal: We show that an electric field applied to a strained topological Dirac\nsemimetal, such as Na3Bi and Cd3As2, induces a spin Hall current that is\nquadratic in the electric field. By regarding the strain as an effective \"axial\nmagnetic field\" for the Dirac electrons, we investigate the electron and spin\ntransport semiclassically in terms of the chiral kinetic theory. The nonlinear\nspin Hall effect arises as the cross effect between the regular Hall effect\ndriven by the axial magnetic field and the anomalous Hall effect coming from\nthe momentum-space topology. It provides an efficient way to generate a fully\nspin-polarized and rectified spin current out of an alternating electric field,\nwhich is sufficiently large and can be directly tuned by the gate voltage and\nthe strain."
    },
    {
        "anchor": "Low lying twisting and acoustic modes of a rotating Bose-Einstein\n  condensate: We present a calculation of the low lying spectrum of a rotating\nBose-Einstein condensate. We show that in a cylindrical geometry, there exist\ntwo linear branches, one associated to usual acoustic excitation, the other\ncorresponding to a twisting mode of the vortex lattice. Using a hydrodynamical\napproach we derive the elasticity coefficient of the vortex lattice and\ncalculate the spectrum of condensate in a three dimensionnal harmonic trap with\ncylindrical symmetry.",
        "positive": "Anomalous energy shift of laterally confined two-dimensional excitons: We theoretically investigate the energy of the ground state exciton confined\nto two-dimensional (2D) monolayers with circular shape. Within an effective\nmass approach employing a nonlocal screening effect on the Coulomb potential\nenergy, we demonstrate how the exciton energy is correlated with the radius of\nthe circle, electron-hole reduced mass, and 2D susceptibility. In addition, we\nshow that a dead layer around the circle edge, into which the electron-hole\npair cannot penetrate, is necessary for understanding the energy shift recently\nobserved in monolayer WSe2 quantum dots."
    },
    {
        "anchor": "Electrical manipulation of an electronic two-state system in Ge/Si\n  quantum dots: We calculate that the electron states of strained self-assembled Ge/Si\nquantum dots provide a convenient two-state system for electrical control. An\nelectronic state localized at the apex of the quantum dot is nearly degenerate\nwith a state localized at the base of the quantum dot. Small electric fields\nshift the electronic ground state from apex-localized to base-localized, which\npermits sensitive tuning of the electronic, optical and magnetic properties of\nthe dot. As one example, we describe how spin-spin coupling between two Ge/Si\ndots can be controlled very sensitively by shifting the individual dot's\nelectronic ground state between apex and base.",
        "positive": "Non-equilibrium supercurrent through mesoscopic ferromagnetic weak links: We consider a mesoscopic normal metal, where the spin degeneracy is lifted by\na ferromagnetic exchange field or Zeeman splitting, coupled to two\nsuperconducting reservoirs. As a function of the exchange field or the distance\nbetween the reservoirs, the supercurrent through this device oscillates with an\nexponentially decreasing envelope. This phenomenon is similar to the tuning of\na supercurrent by a non-equilibrium quasiparticle distribution between two\nvoltage-biased reservoirs. We propose a device combining the exchange field and\nnon-equilibrium effects, which allows us to observe a range of novel phenomena.\nFor instance, part of the field-suppressed supercurrent can be recovered by a\nvoltage between the additional probes."
    },
    {
        "anchor": "Digital quantum simulation of dynamical topological invariants on\n  near-term quantum computers: Programmable quantum processors are suitable platforms for simulating quantum\nsystems, of which topological phases are of particular interest. We simulate\nthe quench dynamics of a one-dimensional system on IBM Q devices. The\ntopological properties of the dynamics are described by the dynamical\ntopological invariants, the dynamical winding number and the time-dependent\nBerry phase, which are simulated with the quantum circuit model. The results\nshow that despite the noise present in the current quantum computers, the\ndynamical topological invariants are robust. Moreover, to investigate the\ninfluence of open quantum system, we analytically solve the master equation in\nLindblad form and show that the dynamical winding number and the change in\nBerry phase are not affected by the dissipation. This study sheds light on the\nrobustness of topological phases on the noisy intermediate-scale quantum\ncomputers.",
        "positive": "Friction Anomalies at First-Order Transition Spinodals: 1T-TaS$_2$: Revealing phase transitions of solids through mechanical anomalies in the\nfriction of nanotips sliding on their surfaces is an unconventional and\ninstructive tool for continuous transitions, unexplored for first-order ones.\nOwing to slow nucleation, first-order structural transformations generally do\nnot occur at the precise crossing of free energies, but hysteretically, near\nthe spinodal temperatures where, below and above the thermodynamic transition\ntemperature, one or the other metastable free energy branches terminates. The\nspinodal transformation, a collective one-shot event with no heat capacity\nanomaly, is easy to trigger by a weak external perturbations. Here we propose\nthat even the gossamer mechanical action of an AFM tip may locally act as a\nsurface trigger, narrowly preempting the spontaneous spinodal transformation,\nand making it observable as a nanofrictional anomaly. Confirming this\nexpectation, the CCDW-NCCDW first-order transition of the important layer\ncompound 1T-TaS$_2$ is shown to provide a demonstration of this effect."
    },
    {
        "anchor": "Minimal model of drag in one-dimensional crystals: Using a non-perturbative classical approach, we study the dynamics of a\nmobile particle interacting with an infinite one-dimensional (1D) chain of\nharmonic oscillators. This minimal system is an effective model for many 1D\ntransport phenomena, such as molecular motion in nanotubes and ionic conduction\nthrough solid-state materials. As expected, coupling between the mobile\nparticle and the chain induces dissipation of the mobile particle's energy.\nHowever, both numerical and analytic results demonstrate an unconventional\nnon-monotonic dependence of the drag on particle speed. In addition, when this\nsystem is subjected to a constant bias, it supports multiple steady-state drift\nvelocities.",
        "positive": "Testing Topological Protection of Edge States in Hexagonal Quantum Spin\n  Hall Candidate Materials: We analyze the detailed structure of topological edge mode protection\noccuring in hexagonal quantum spin Hall (QSH) materials. We focus on\nbismuthene, antimonene, and arsenene on a SiC substrate, which, due to their\nlarge bulk gap, may offer new opportunities for room-temperature QSH\napplications. While time reversal symmetry is responsible for the principal\nsymmetry protected character of QSH states, the hexagonal edge terminations\nyield further aspects of crystal symmetry which affect the topological\nprotection. We show that armchair QSH edge states remain gapless under an\nin-plane magnetic field in the direction along the edge, a hallmark of their\ntopological crystalline protection. In contrast, an out-of-plane magnetic field\nopens a gap of the order of a few meV within realistic ranges of parameters. We\nuse these intriguing signatures of armchair QSH edge states to predict\nexperimentally testable fingerprints of their additional topological\ncrystalline character and their helicity emerging in tunneling spectroscopy and\nballistic magnetotransport."
    },
    {
        "anchor": "Record-quality GaAs two-dimensional hole systems: The complex band structure, large spin-orbit induced band splitting, and\nheavy effective mass of two-dimensional (2D) hole systems hosted in GaAs\nquantum wells render them rich platforms to study many-body physics and\nballistic transport phenomena. Here we report ultra-high-quality (001) GaAs 2D\nhole systems, fabricated using molecular beam epitaxy and modulation doping,\nwith mobility values as high as $5.8\\times10^6$ cm$^2$/Vs at a hole density of\n$p=1.3\\times10^{11}$ /cm$^2$, implying a mean-free path of $\\simeq27$ $\\mu$m.\nIn the low-temperature magnetoresistance trace of this sample, we observe\nhigh-order fractional quantum Hall states up to the Landau level filling\n$\\nu=12/25$ near $\\nu=1/2$. Furthermore, we see a deep minimum develop at\n$\\nu=1/5$ in the magnetoresistance of a sample with a much lower hole density\nof $p=4.0\\times10^{10}$ /cm$^2$ where we measure a mobility of $3.6\\times10^6$\ncm$^2$/Vs. These improvements in sample quality were achieved by reduction of\nresidual impurities both in the GaAs channel and the AlGaAs barrier material,\nas well as optimization in design of the sample structure.",
        "positive": "Tunnel Magnetoresistance of a Single-Molecule Junction: Based on the non-equilibrium Green's function (NEGF) technique and the\nLandauer-B\\\"{u}ttiker theory, the possibility of a molecular spin-electronic\ndevice, which consists of a single C$_{60}$ molecule attached to two\nferromagnetic electrodes with finite cross sections, is investigated. By\nstudying the coherent spin-dependent transport through the energy levels of the\nmolecule, it is shown that the tunnel magnetoresistance (TMR) of the molecular\njunction depends on the applied voltages and the number of contact points\nbetween the device electrodes and the molecule. The TMR values more than 60%\nare obtained by adjusting the related parameters."
    },
    {
        "anchor": "Symmetric reflection line resonator for semiconductor circuit quantum\n  electrodynamics: We have designed and fabricated a half-wavelength reflection line resonator\n(RLR) that consists of a pair of two coupled microstrip lines on a GaAs/AlGaAs\nheterostructure. By changing the top gate voltage on a square of two\ndimensional electron gas under the resonator, a large range of the quality\nfactors can be obtained. Energy loss in the two-dimensional electron gas can be\nminimized, thus realizing a versatile resonator suitable for integration with\nsemiconductor quantum circuits.",
        "positive": "Kinks in buckled graphene uncompressed and compressed in the\n  longitudinal direction: In this Chapter we provide a review of the main results obtained in the\nmodeling of graphene kinks and antikinks, which are elementary topological\nexcitations of buckled graphene membranes. We introduce the classification of\nkinks, as well as discuss kink-antikink scattering, and radiation-kink\ninteraction. We also report some new findings including i) the evidence that\nthe kinetic energy of graphene kinks is described by a relativistic expression,\nand ii) demonstration of damped dynamics of kinks in membranes compressed in\nthe longitudinal direction. Special attention is paid to highlight the\nsimilarities and differences between the graphene kinks and kinks in the\nclassical scalar $\\phi^4$ theory. The unique properties of graphene kinks\ndiscussed in this Chapter may find applications in nanoscale motion."
    },
    {
        "anchor": "Donors and Deep Acceptors in $\u03b2$-Ga2O3: We have studied the properties of Si, Ge shallow donors and Fe, Mg deep\nacceptors in $\\beta$-Ga2O3 through temperature dependent van der Pauw and Hall\neffect measurements of samples grown by a variety of methods, including\nedge-defined film-fed (EFG), Czochralski (CZ), molecular beam epitaxy (MBE),\nand low pressure chemical vapor deposition (LPCVD). Through simultaneous,\nself-consistent fitting of the temperature dependent carrier density and\nmobility, we are able to accurately estimate the donor energy of Si and Ge to\nbe 30 meV in $\\beta$-Ga2O3. Additionally, we show that our measured Hall effect\ndata are consistent with Si and Ge acting as typical shallow donors, rather\nthan shallow DX centers. High temperature Hall effect measurement of Fe doped\n$\\beta$-Ga2O3 indicates that the material remains weakly n-type even with the\nFe doping, with an acceptor energy of 860 meV relative to the conduction band\nfor the Fe deep acceptor. Van der Pauw measurements of Mg doped Ga2O3 indicate\nan activation energy of 1.1 eV, as determined from the temperature dependent\nconductivity.",
        "positive": "Post-processing of real-time quantum event measurements for an optimal\n  bandwidth: Single electron tunneling and its transport statistics have been studied for\nsome time using high precision charge detectors. However, this type of\ndetection requires advanced lithography, optimized material systems and low\ntemperatures (mK). A promising alternative, recently demonstrated, is to\nexploit an optical transition that is turned on or off when a tunnel event\noccurs. High bandwidths should be achievable with this approach, although this\nhas not been adequately investigated so far. We have studied low temperature\nresonance fluorescence from a self-assembled quantum dot embedded in a diode\nstructure. We detect single photons from the dot in real time and evaluate the\nrecorded data only after the experiment, using post-processing to obtain the\nrandom telegraph signal of the electron transport. This is a significant\ndifference from commonly used charge detectors and allows us to determine the\noptimal time resolution for analyzing our data. We show how this\npost-processing affects both the determination of tunneling rates using\nwaiting-time distributions and statistical analysis using full-counting\nstatistics. We also demonstrate, as an example, that we can analyze our data\nwith bandwidths as high as 350 kHz. Using a simple model, we discuss the\nlimiting factors for achieving the optimal bandwidth and propose how a time\nresolution of more than 1 MHz could be achieved."
    },
    {
        "anchor": "Enhanced spin relaxation time due to electron-electron scattering in\n  semiconductors: We present a detailed experimental and theoretical analysis of the spin\ndynamics of two-dimensional electron gases (2DEGs) in a series of n-doped\nGaAs/AlGaAs quantum wells. Picosecond-resolution polarized pump-probe\nreflection techniques were applied in order to study in detail the\ntemperature-, concentration- and quantum-well-width- dependencies of the spin\nrelaxation rate of a small photoexcited electron population. A rapid\nenhancement of the spin life-time with temperature up to a maximum near the\nFermi temperature of the 2DEG was demonstrated experimentally. These\nobservations are consistent with the D'yakonov-Perel' spin relaxation mechanism\ncontrolled by electron-electron collisions. The experimental results and\ntheoretical predictions for the spin relaxation times are in good quantitative\nagreement.",
        "positive": "Magnetic field induced shell-to-core confinement transition in type-II\n  semiconductor quantum wires: We investigate the excitonic properties of a core-multishell semiconductor\nnanowire with type-II band mismatch, i.e. with spatially separated electrons\nand holes, under an external magnetic field. Our results demonstrate that,\ndepending on the core wire radius, the carrier in the type-II band exhibits\neither a quantum dot-like or a quantum ring-like energy spectrum, corresponding\nto a carrier confinement in the core wire or in the outer shell, respectively.\nIn the latter, a shell-to-core confinement transition can be induced by\nincreasing the magnetic field intensity, which may lead to interesting\nphotocurrent properties of these confining structures, tunable by the external\nfield."
    },
    {
        "anchor": "Appearance of hinge states in second-order topological insulators via\n  the cutting procedure: In recent years, second-order topological insulators have been proposed as a\nnew class of topological insulators. Second-order topological insulators are\nmaterials with gapped bulk and surfaces, but with topologically protected\ngapless states at the intersection of two surfaces. These gapless states are\ncalled hinge states. In this paper, we give a general proof that any insulators\nwith inversion symmetry and gapped surface in class A always have hinge states\nwhen the $\\mathbb{Z}_{4}$ topological index $\\mu_{1}$ is $\\mu_{1}=2$. We\nconsider a three-dimensional insulator whose boundary conditions along two\ndirections change by changing the hopping amplitudes across the boundaries. We\nstudy behaviors of gapless states through continuously changing boundary\nconditions along the two directions, and reveal that the behaviors of gapless\nstates result from the $\\mathbb{Z}_{4}$ strong topological index. From this\ndiscussion, we show that gapless states inevitably appear at the hinge of a\nthree-dimensional insulator with gapped surfaces when the strong topological\nindex is $\\mathbb{Z}_{4}=2$ and the weak topological indices are\n$\\nu_{1}=\\nu_{2}=\\nu_{3}=0$.",
        "positive": "Tunable quantum spin Hall effect in double quantum wells: The field of topological insulators (TIs) is rapidly growing. Concerning\npossible applications, the search for materials with an easily controllable TI\nphase is a key issue. The quantum spin Hall effect, characterized by a single\npair of helical edge modes protected by time-reversal symmetry, has been\ndemonstrated in HgTe-based quantum wells (QWs) with an inverted bandgap. We\nanalyze the topological properties of a generically coupled HgTe-based double\nQW (DQW) and show how in such a system a TI phase can be driven by an\ninter-layer bias voltage, even when the individual layers are non-inverted. We\nargue, that this system allows for similar (layer-)pseudospin based physics as\nin bilayer graphene but with the crucial absence of a valley degeneracy."
    },
    {
        "anchor": "Spin Depolarization in Quantum Wires Polarized Spontaneously in a Zero\n  Magnetic Field: The conditions for a spontaneous spin polarization in a quantum wire\npositioned in a zero magnetic field are analyzed under weak population of\none-dimensional subbands that gives rise to the efficient quenching of the\nkinetic energy by the exchange energy of carriers. The critical linear\nconcentration of carriers above which the quasi one-dimensional gas undergoes a\ncomplete spin depolarization is determined by the Hartree-Fock approximation.\nThe dependence of the critical linear concentration on the concentration of\ncarriers is defined to reveal the interplay of the spin depolarization with the\nevolution of the 0.7 (2e2/h) feature in the quantum conductance staircase from\nthe e2/h to 3/2 (e2/h) values. This dependence is used to study the effect of\nthe hole concentration on the 0.7 (2e2/h) feature in the quantum conductance\nstaircase of the quantum wire prepared inside the p-type silicon quantum well\nusing the split-gate technique. The 1D channel is demonstrated to be\nspin-polarized at the linear concentration of holes lower than the critical\nlinear concentration, because the 0.7 (2e2/h) feature is close to the value of\n0.5 (2e2/h) that indicates the spin degeneracy lifting for the first step of\nthe quantum conductance staircase. The 0.7 (2e2/h) feature is found to take\nhowever its normal magnitude when the linear concentration of holes attains the\ncritical value corresponding to the spin depolarization. The variations in the\nheight of the 0.7 (2e2/h) feature observed in the hole quantum conductance\nstaircase that is revealed by the p-type silicon quantum wire seem to be\nrelated to the evidences of the quantum conductance staircase obtained by\nvarying the concentration of electrons in the 1D channel prepared inside the\nGaAs-AlGaAs heterojunction.",
        "positive": "Nonequilibrium transport in mesoscopic multi-terminal SNS Josephson\n  junctions: We report the results of several nonequilibrium experiments performed on\nsuperconducting/normal/superconducting (S/N/S) Josephson junctions containing\neither one or two extra terminals that connect to normal reservoirs. Currents\ninjected into the junctions from the normal reservoirs induce changes in the\nelectron energy distribution function, which can change the properties of the\njunction. A simple experiment performed on a 3-terminal sample demonstrates\nthat quasiparticle current and supercurrent can coexist in the normal region of\nthe S/N/S junction. When larger voltages are applied to the normal reservoir,\nthe sign of the current-phase relation of the junction can be reversed,\ncreating a \"$\\pi$-junction.\" We compare quantitatively the maximum critical\ncurrents obtained in 4-terminal $\\pi$-junctions when the voltages on the normal\nreservoirs have the same or opposite sign with respect to the superconductors.\nWe discuss the challenges involved in creating a \"Zeeman\" $\\pi$-junction with a\nparallel applied magnetic field and show in detail how the orbital effect\nsuppresses the critical current. Finally, when normal current and supercurrent\nare simultaneously present in the junction, the distribution function develops\na spatially inhomogeneous component that can be interpreted as an effective\ntemperature gradient across the junction, with a sign that is controllable by\nthe supercurrent. Taken as a whole, these experiments illustrate the richness\nand complexity of S/N/S Josephson junctions in nonequilibrium situations."
    },
    {
        "anchor": "Enhancement of carbon nanotube photoluminescence by photonic crystal\n  nanocavities: Photonic crystal nanocavities are used to enhance photoluminescence from\nsingle-walled carbon nanotubes. Micelle-encapsulated nanotubes are deposited on\nnanocavities within Si photonic crystal slabs and confocal microscopy is used\nto characterize the devices. Photoluminescence spectra and images reveal\nnanotube emission coupled to nanocavity modes. The cavity modes can be tuned\nthroughout the emission wavelengths of carbon nanotubes, demonstrating the\nability to enhance photoluminescence from a variety of chiralities.",
        "positive": "Manipulation of Valley Isospins in Strained Graphene for Valleytronics: Graphene's outstanding mechanical properties lend to strain engineering,\nallowing for future valleytronics and nanoelectromechanic applications. In this\nwork, we have found that a Gaussian-shaped strain on a graphene p-n junction\nresults in quantum Hall conductance oscillations due to the rotated angle\nbetween valley isospins at the graphene armchair edges. Furthermore, additional\nFano resonances were observed as the value of the strain-induced\npseudo-magnetic field approaches that of the external magnetic field. The\nlifted valley degeneracy, stemming from the interplay between the real and\npseudo-magnetic fields, results in clearly valley-resolved Fano resonances.\nExploring strain engineering as a means to control conductance through valley\nisospin manipulation is believed to open the door to potential graphene\nvalleytronic devices."
    },
    {
        "anchor": "Detecting Spin-Polarized Currents in Ballistic Nanostructures: We demonstrate a mesoscopic spin polarizer/analyzer system that allows the\nspin polarization of current from a quantum point contact in an in-plane\nmagnetic field to be measured. A transverse focusing geometry is used to couple\ncurrent from an emitter point contact into a collector point contact. At large\nin-plane fields, with the point contacts biased to transmit only a single spin\n(g < e^2/h), the voltage across the collector depends on the spin polarization\nof the current incident on it. Spin polarizations of greater than 80% are found\nfor both emitter and collector at 300mK and 7T in-plane field.",
        "positive": "Light-induced half-quantized Hall effect and axion insulator: Motivated by the recent experimental realization of the half-quantized Hall\neffect phase in a three-dimensional (3D) semi-magnetic topological insulator\n[M. Mogi et al., Nature Physics 18, 390 (2022)], we propose a scheme for\nrealizing the half-quantized Hall effect and axion insulator in experimentally\nmature 3D topological insulator heterostructures. Our approach involves\noptically pumping and/or magnetically doping the topological insulator surface,\nsuch as to break time reversal and gap out the Dirac cones. By toggling between\nleft and right circularly polarized optical pumping, the sign of the\nhalf-integer Hall conductance from each of the surface Dirac cones can be\ncontrolled, such as to yield half-quantized ($0+1/2$), axion ($-1/2+1/2=0$),\nand Chern ($1/2+1/2=1$) insulator phases. We substantiate our results based on\ndetailed band structure and Berry curvature numerics on the Floquet Hamiltonian\nin the high-frequency limit. Our paper showcases how topological phases can be\nobtained through mature experimental approaches such as magnetic layer doping\nand circularly polarized laser pumping and opens up potential device\napplications such as a polarization chirality-controlled topological\ntransistor."
    },
    {
        "anchor": "Memory effects in ac hopping conductance in the quantum Hall effect\n  regime: Possible manifestation of DX$^-$ centers: Using simultaneous measurements of the attenuation and velocity of surface\nacoustic waves propagating along GaAs/Al$_{0.3}$Ga$_{0.7}$As heterostructures,\ncomplex ac conductance of the latters has been determined. In the magnetic\nfields corresponding to the middles of the Hall plateaus both the ac\nconductance, $\\sigma (\\omega)$, and the sheet electron density, $n_s$, in the\ntwo-dimensional conducting layer turn out to be dependent on the samples'\ncooling rate. As a result, the sample ``remembers'' the cooling conditions. The\ncomplex conductance is strongly dependent on an infrared illumination which\nalso changes both $\\sigma (\\omega)$ and $n_s$. Remarkably, the correlation\nbetween $\\sigma (\\omega)$ and $n_s$ is \\emph{universal}, i.e. it is independent\nof the way to change these quantities. The results are attributed to\ntwo-electron defects (so-called $DX^-$ centers) located in the Si doped layer.",
        "positive": "Drude weight, plasmon dispersion, and a.c. conductivity in doped\n  graphene sheets: We demonstrate that the plasmon frequency and Drude weight of the electron\nliquid in a doped graphene sheet are strongly renormalized by electron-electron\ninteractions even in the long-wavelength limit. This effect is not captured by\nthe Random Phase Approximation (RPA), commonly used to describe electron fluids\nand is due to coupling between the center of mass motion and the pseudospin\ndegree of freedom of the graphene's massless Dirac fermions. Making use of\ndiagrammatic perturbation theory to first order in the electron-electron\ninteraction, we show that this coupling enhances both the plasmon frequency and\nthe Drude weight relative to the RPA value. We also show that interactions are\nresponsible for a significant enhancement of the optical conductivity at\nfrequencies just above the absorption threshold. Our predictions can be checked\nby far-infrared spectroscopy or inelastic light scattering."
    },
    {
        "anchor": "Computational study of III-V direct-gap semiconductors for\n  thermoradiative cell applications: We investigate the performance of thermoradiative (TR) cells using the III-V\ngroup of semiconductors, which include GaAs, GaSb, InAs, and InP, with the aim\nof determining their efficiency and finding the best TR cell materials among\nthe III-V group. The TR cells generate electricity from thermal radiation, and\ntheir efficiency is influenced by several factors such as the bandgap,\ntemperature difference, and absorption spectrum. To create a realistic model,\nwe incorporate sub-bandgap and heat losses in our calculations and utilize\ndensity-functional theory to determine the energy gap and optical properties of\neach material. Our findings suggest that the effect of absorptivity on the\nmaterial, especially when the sub-bandgap and heat losses are considered, can\ndecrease the efficiency of TR cells. However, careful treatment of the\nabsorptivity indicates that not all materials have the same trend of decrease\nin the TR cell efficiency when taking the loss mechanisms into account. We\nobserve that GaSb exhibits the highest power density, while InP demonstrates\nthe lowest one. Moreover, GaAs and InP exhibit relatively high efficiency\nwithout the sub-bandgap and heat losses, whereas InAs display lower efficiency\nwithout considering the losses, yet exhibit higher resistance to sub-bandgap\nand heat losses compared to the other materials, thus effectively becoming the\nbest TR cell material in the III-V group of semiconductors.",
        "positive": "Maximum efficiency of state-space models of molecular scale engines: The performance of nano-scale energy conversion devices is studied in the\nframework of state-space models where a device is described by a graph\ncomprising states and transitions between them represented by nodes and links,\nrespectively. Particular segments of this network represent input (driving) and\noutput processes whose properly chosen flux ratio provides the energy\nconversion efficiency. Simple cyclical graphs yield Carnot efficiency for the\nmaximum conversion yield. We give general proof that opening a link that\nseparate between the two driving segments always leads to reduced efficiency.\nWe illustrate this general result with a simple model of an organic\nphotovoltaic cell, where such an intersecting link corresponds to non-radiative\ncarriers recombination and where the reduced maximum efficiency is manifested\nas a smaller open-circuit voltage."
    },
    {
        "anchor": "Emergence of excitonic superfluid at topological-insulator surfaces: Excitons are spin integer particles that are predicted to condense into a\ncoherent quantum state at sufficiently low temperature, and exciton condensates\ncan be realized at much higher temperature than condensates of atoms because of\nstrong Coulomb binding and small mass. Signatures of exciton condensation have\nbeen reported in double quantum wells1-4, microcavities5, graphene6, and\ntransition metal dichalcogenides7. Nonetheless, transport of exciton\ncondensates is not yet understood and it is unclear whether an exciton\ncondensate is a superfluid8,9 or an insulating electronic crystal10,11.\nTopological insulators (TIs) with massless particles and unique spin textures12\nhave been theoretically predicted13 as a promising platform for achieving\nexciton condensation. Here we report experimental evidence of excitonic\nsuperfluid phase on the surface of three-dimensional (3D) TIs. We unambiguously\nconfirmed that electrons and holes are paired into charge neutral bound states\nby the electric field independent photocurrent distributions. And we observed a\nmillimetre-long transport distance of these excitons up to 40 K, which strongly\nsuggests dissipationless propagation. The robust macroscopic quantum states\nachieved with simple device architecture and broadband photoexcitation at\nrelatively high temperature are expected to find novel applications in quantum\ncomputations and spintronics.",
        "positive": "Formation and control of wrinkles in graphene by the wedging transfer\n  method: We study the formation of wrinkles in graphene upon wet transfer onto a\ntarget substrate, whereby draining of water appears to play an important role.\nWe are able to control the orientation of the wrinkles by tuning the surface\nmorphology. Wrinkles are absent in flakes transferred to strongly hydrophobic\nsubstrates, a further indication of the role of the interaction of water with\nthe substrate in wrinkle formation. The electrical and structural integrity of\nthe graphene is not affected by the wrinkles, as inferred from Raman\nmeasurements and electrical conductivity measurements."
    },
    {
        "anchor": "Spin Hall effect associated with SU(2) gauge field: In this paper, we focus on the connection between spin Hall effect and spin\nforce. Here we investigate that the spin force due to spin-orbit coupling,\nwhich in two-dimensional system is equivalent to forces of Hirsch and\nChudnovsky besides constant factors 3 and 3/2 respectively, is a part of\nclassic Anandan force, and that the spin Hall effect is an anomalous Hall\neffect. Furthermore, we develop the method of AC phase to derive the formula\nfor the spin force, and find that the most basic spin Hall effect originates\nfrom the AC phase and is therefore an intrinsic quantum mechanical property of\nspin. This method differs from approach of Berry phase in the study of\nanomalous Hall effect, which is the intrinsic property of the perfect crystal.\nOn the other hand, we use an elegant skill to show that the Chudnovsky-Drude\nmodel is reasonable, and further have improved the theoretical values of spin\nHall conductivity of Chudnovsky. Compared to the theoretical values of spin\nHall conductivity in the Chudnovsky-Drude model, ours are in better agreement\nwith experimentation. Finally, we discuss the relation between spin Hall effect\nand fractional statistics.",
        "positive": "Geometry of projected connections, Zak phase, and electric polarization: The concept of the Zak phase lies at the core of the modern theory of\nelectric polarization. It is defined using the components of the Bloch wave\nfunctions in a certain basis, which is not captured by the standard expression\nfor Berry potential. We provide a consistent geometric interpretation of the\nZak phase in terms of projected connections. In the context of Bloch states, we\nrelate the transformation law of projected Berry potential with classical\ncurrents that contribute to the time derivative of the electric polarization.\nThis gives a new argument for the Zak phase formula for the electronic\ncontribution to the polarization. We demonstrate that the Wannier functions\nplay a key role in the description of an adiabatic current in a periodic\nsystem."
    },
    {
        "anchor": "Modeling of cotunneling in quantum dot systems: Transport through nanosystems is treated within the second order von Neumann\napproach. This approach bridges the gap between rate equations which neglect\nlevel broadening and cotunneling, and the transmission formalism, which is\nessentially based on the single-particle picture thereby treating many-particle\ninteractions on an approximate level. Here we provide an alternative\npresentation of the method in order to clarify the underlying structure.\nFurthermore we apply it to the problem of cotunneling. It is shown that both\nelastic and inelastic cotunneling can be described quantitatively, while the\ntransmission approach with a mean-field treatment of the interaction provides\nan artificial bistability.",
        "positive": "Calculation of the graphene C 1$\\textit{s}$ core level binding energy: X-ray photoelectron spectroscopy (XPS) combined with first principles\nmodeling is a powerful tool for determining the chemical composition and\nelectronic structure of novel materials. Of these, graphene is an especially\nimportant model system for understanding the properties of other carbon\nnanomaterials. Here, we calculate the carbon 1$\\textit{s}$ core level binding\nenergy of pristine graphene using two methods based on density functional\ntheory total energy differences: a calculation with an explicit core-hole\n($\\Delta$KS), and a novel all-electron extension of the delta self-consistent\nfield ($\\Delta$SCF) method. We study systematically their convergence and\ncomputational workload, and the dependence of the energies on the chosen\nexchange-correlation functional. The $\\mathrm{\\Delta}$SCF method is\ncomputationally more expensive, but gives consistently higher C 1$\\textit{s}$\nbinding energies. Although there is a significant functional dependence, the\nbinding energy calculated using the PBE functional is found to be remarkably\nclose to what has been measured for graphite."
    },
    {
        "anchor": "Anomalous Phase Dynamics of Driven Graphene Josephson Junctions: Josephson junctions with weak-links of exotic materials allow the elucidation\nof the Josephson effect in previously unexplored regimes. Further, such devices\noffer a direct probe of novel material properties, for example in the search\nfor Majorana fermions. In this work, we report on DC and AC Josephson effect of\nhigh-mobility, hexagonal boron nitride (h-BN) encapsulated graphene Josephson\njunctions. On the application of RF radiation, we measure phase-locked Shapiro\nsteps. An unexpected bistability between $\\pm 1$ steps is observed with\nswitching times on the order of seconds. A critical scaling of a bistable state\nis measured directly from the switching time, allowing for direct comparison to\nnumerical simulations. We show such intermittent chaotic behavior is a\nconsequence of the nonlinear dynamics of the junction and has a sensitive\ndependence on the current-phase relation. This work draws connections between\nnonlinear phenomena in dynamical systems and their implications for ongoing\ncondensed matter experiments exploring topology and exotic physics.",
        "positive": "Graphene-like metallic-on-silicon field effect transistor: In this manuscript, we present a field effect transistor with a channel\nconsisting of a two-dimensional electron gas located at the interface between\nan ultrathin metallic film of Ni and a p-type Si(111) substrate. We have\ndemonstrated that the two-dimensional electron gas channel is modulated by the\ngate voltage. The dependence of the drain current on the drain voltage has no\nsaturation region, similar to a field effect transistor based on graphene.\nHowever, the transport in this transistor is not ambipolar, as in graphene, but\nunipolar."
    },
    {
        "anchor": "Spin-wave frequency combs: We experimentally demonstrate the generation of spin-wave frequency combs\nbased on the nonlinear interaction of propagating spin waves in a\nmicrostructured waveguide. By means of time and space-resolved Brillouin light\nscattering spectroscopy, we show that the simultaneous excitation of spin waves\nwith different frequencies leads to a cascade of four-magnon scattering events\nwhich ultimately results in well-defined frequency combs. Their spectral weight\ncan be tuned by the choice of amplitude and frequency of the input signals.\nFurthermore, we introduce a model for stimulated four-magnon scattering which\ndescribes the formation of spin-wave frequency combs in the frequency and time\ndomain.",
        "positive": "Scattering of Electrons between Edge and Two-Dimensional States of a\n  Two-Dimensional Topological Insulator and the Conductivity of the Topological\n  Insulator Strip in a Metallic State: The lifetime of electrons on edge states of a two-dimensional topological\ninsulator against the background of an allowed two-dimensional band has been\ndetermined. It has been shown that this time in the case of scattering on\nCoulomb impurities can be significantly larger than the mean free time of\ntwo-dimensional electrons. As a result, the conductivity of the metallic\ntwo-dimensional topological insulator strip can be determined primarily by edge\nstates."
    },
    {
        "anchor": "Tunneling effect on composite fermion pairing state in bilayer quantum\n  Hall system: We discuss the composite fermion pairing state in bilayer quantum Hall\nsystems. After the evaluation of the range of the inter-layer separation in\nwhich the quantum Hall state is stabilized, we discuss the effect of\ninter-layer tunneling on the composite fermion pairing state at \\nu=1/2. We\nshow that there is a cusp at the transition point between the Halperin (3,3,1)\nstate and the Pfaffian state.",
        "positive": "Finite voltage shot noise in normal-metal - superconductor junctions: We express the low-frequency shot noise in a disordered normal-metal -\nsuperconductor (NS) junction at finite (subgap) voltage in terms of the normal\nscattering amplitudes and the Andreev reflection amplitude. In the multichannel\nlimit, the conductance exhibits resonances which are accompanied by an\nenhancement of the (differential) shot noise. In the study of multichannel\nsingle and double barrier junctions we discuss the noise properties of coherent\ntransport at low versus high voltage with respect to the Andreev level spacing."
    },
    {
        "anchor": "Spin-valley locking in Kekul\u00e9-distorted graphene with Dirac-Rashba\n  interactions: The joint effects of Kekul\\'e lattice distortions and Rashba-type spin-orbit\ncoupling on the electronic properties of graphene are explored. We modeled the\nposition dependence of the Rashba energy term in a manner that allows its\nseamless integration into the scheme introduced by Gamayun et al.[New J. Phys.\n20, 023016 (2018)] to describe graphene with Kekul\\'e lattice distortion.\nParticularly for the Kekul\\'e-Y texture, the effective low energy Dirac\nHamiltonian contains a new spin-valley locking term, in addition to the\nwell-known Rashba-induced momentum-pseudospin and spin-pseudospin couplings,\nand the Kekul\\'e-induced momentum-valley coupling term. We report on the\nlow-energy band structure and Landau level spectra of Rashba-spin-orbit-coupled\nKek-Y graphene, and propose an experimental scheme to discern between the\npresence of Rashba spin-orbit coupling, Kek-Y lattice distortion, and both,\nbased on doping-dependent magnetotransport measurements.",
        "positive": "Adiabatic quantum motors: When parameters are varied periodically, charge can be pumped through a\nmesoscopic conductor without applied bias. Here, we consider the inverse effect\nin which a transport current drives a periodic variation of an adiabatic degree\nof freedom. This provides a general operating principle for adiabatic quantum\nmotors, for which we develop a comprehensive theory. We relate the work\nperformed per cycle on the motor degree of freedom to characteristics of the\nunderlying quantum pump and discuss the motor's efficiency. Quantum motors\nbased on chaotic quantum dots operate solely due to quantum interference,\nmotors based on Thouless pumps have ideal efficiency."
    },
    {
        "anchor": "Spatial coherence of room-temperature monolayer WSe$_2$\n  exciton-polaritons in a trap: The emergence of spatial and temporal coherence of light emitted from\nsolid-state systems is a fundamental phenomenon, rooting in a plethora of\nmicroscopic processes. It is intrinsically aligned with the control of\nlight-matter coupling, and canonical for laser oscillation. However, it also\nemerges in the superradiance of multiple, phase-locked emitters, and more\nrecently, coherence and long-range order have been investigated in bosonic\ncondensates of thermalized light, as well as in exciton-polaritons driven to a\nground state via stimulated scattering. Here, we experimentally show that the\ninteraction between photons in a Fabry-Perot microcavity and excitons in an\natomically thin WSe$_2$ layer is sufficient such that the system enters the\nhybridized regime of strong light-matter coupling at ambient conditions. Via\nMichelson interferometry, we capture clear evidence of increased spatial and\ntemporal coherence of the emitted light from the spatially confined system\nground-state. The coherence build-up is accompanied by a threshold-like\nbehaviour of the emitted light intensity, which is a fingerprint of a polariton\nlaser effect. Valley-physics is manifested in the presence of an external\nmagnetic field, which allows us to manipulate K and K' polaritons via the\nValley-Zeeman-effect. Our findings are of high application relevance, as they\nconfirm the possibility to use atomically thin crystals as simple and versatile\ncomponents of coherent light-sources, and in valleytronic applications at room\ntemperature.",
        "positive": "Optical absorption properties of laser-dressed matter: Characterizing and controlling matter driven far from equilibrium represents\na major challenge for science and technology. Here we develop a theory for the\noptical absorption of electronic materials driven far from equilibrium by\nresonant and non-resonant lasers. In it, the interaction between matter and the\ndriving light is treated exactly through a Floquet analysis, while the effects\nof the probing light are captured to first order in perturbation theory. The\nresulting equations are reminiscent to those for equilibrium absorption but\nwith the Floquet modes playing the role of the pristine eigenstates. The\nformalism is employed to characterize the optical properties of a model\nnanoscale semiconductor dressed by non-resonant light of intermediate intensity\n(non-perturbative, but non-ionizing). As shown, non-resonant light can\nreversibly turn this transparent semiconductor into a broadband absorber and\nopen strong absorption/stimulated emission bands at very low frequencies (~\nmeV). Further, the absorption spectra of the driven material exhibit periodic\nfeatures energetically spaced by the photon energy of the driving light that\nreflect the periodic structure of the Floquet bands. These developments offer a\ngeneral approach to understand and predict the emergent optical properties of\nmaterials dressed by the electric field of light, and catalyze the design of\nlaser-dressed materials with desired optical properties."
    },
    {
        "anchor": "Quantum magnetic oscillations in Weyl semimetals with tilted nodes: A Weyl semimetal (WSM)\\ is a three-dimensional topological phase of matter\nwhere pairs of nondegenerate bands cross at isolated points in the Brillouin\nzone called Weyl nodes. Near these points, the electronic dispersion is gapless\nand linear. A magnetic field $B$ changes this dispersion into a set of Landau\nlevels which are dispersive along the direction of the magnetic field only. The\n$n=0$ Landau level is special since its dispersion$\\ $is linear and\nunidirectional. The presence of this chiral level distinguishes Weyl from\nSchr\\\"{o}dinger fermions. In this paper, we study the quantum oscillations of\nthe orbital magnetization and magnetic susceptibility in Weyl semimetals. We\ngeneralise earlier works% \\cite{Mikitik2019} on these De Haas-Van Alphen\noscillations by considering the effect of a tilt of the Weyl nodes. We study\nhow the fundamental period of the oscillations in the small $B$ limit and the\nstrength of the magnetic field $B_{1}$ required to reach the quantum limit are\nmodified by the magnitude and orientation of the tilt vector $\\mathbf{t}$. We\nshow that the magnetization from a single node is finite in the $B\\rightarrow\n0$ limit. Its sign depends on the product of the chirality and sign of the tilt\ncomponent along the magnetic field direction. We also study the magnetic\noscillations from a pair of Weyl nodes with opposite chirality and with\nopposite or identical tilt. Our calculation shows that these two cases lead to\na very different behavior of the magnetization in the small and large $B$\nlimits. We finally consider the effect of an energy shift $\\pm \\Delta _{0}$ of\na pair of Weyl nodes on the magnetic oscillations. We assume a constant density\nof carriers so that both nodes share a common Fermi level. Our calculation can\neasily be extended to a WSM with an arbitrary number of pairs of Weyl nodes.",
        "positive": "On-and-off chip cooling of a Coulomb blockade thermometer down to 2.8 mK: Cooling nanoelectronic devices below 10 mK is a great challenge since thermal\nconductivities become very small, thus creating a pronounced sensitivity to\nheat leaks. Here, we overcome these difficulties by using adiabatic\ndemagnetization of \\emph{both} the electronic leads \\emph{and} the large\nmetallic islands of a Coulomb blockade thermometer. This reduces the external\nheat leak through the leads and also provides on-chip refrigeration, together\ncooling the thermometer down to 2.8$\\pm$0.1 mK. We present a thermal model\nwhich gives a good qualitative account and suggests that the main limitation is\nheating due to pulse tube vibrations. With better decoupling, temperatures\nbelow 1 mK should be within reach, thus opening the door for microkelvin\nnanoelectronics."
    },
    {
        "anchor": "Effective Land\u00e9 factors of electrons and holes in lead chalcogenide\n  nanocrystals: The Land\\'e or g-factors of charge carriers in solid state systems provide\ninvaluable information about response of quantum states to external magnetic\nfields and are key ingredients in description of spin-dependent phenomena in\nnanostructures. We report on the comprehensive theoretical analysis of electron\nand hole g-factors in lead chalcogenide nanocrystals. By combining symmetry\nanalysis, atomistic calculations, and extended k.p theory, we relate calculated\nlinear-in-magnetic field energy splittings of confined electron states in\nnanocrystals to the intravalley g-factors of the multi-valley bulk materials,\nrenormalized due to the quantum confinement. We demonstrate that this\nrenormalization is correctly reproduced by analytical expressions derived in\nthe framework of the extended k.p model.",
        "positive": "Long-range hopping and indexing assumption in one-dimensional\n  topological insulators: In this paper, we show that the introduction of long-range hoppings in 1D\ntopological insulator models implies that different possibilities of site\nindexing must be considered when determining the bulk topological invariants in\norder to avoid the existence of hidden symmetries. The particular case of the\nextended SSH chain is addressed as an example where such behavior occurs. In\nthis model, the introduction of long-range hopping terms breaks the bipartite\nproperty and a band inversion occurs in the band structure as the relative\nvalues of the hopping terms change, signaling a crossover between hopping\nparameter regions of \"influence\" of different chiral symmetries. Furthermore,\nedge states become a linear combination of edge-like states with different\nlocalization lengths and reflect the gradual transition between these different\nchiral symmetries."
    },
    {
        "anchor": "Few-electron semiconductor quantum dots with Gaussian confinement: We have performed Hartree-Fock calculations of electronic structure of N \\le\n10 electrons in a quantum dot modeled with a confining Gaussian potential well.\nWe discuss the conditions for the stability of N bound electrons in the system.\nWe show that the most relevant parameter determining the number of bound\nelectrons is $V_0 R^2$. Such a property arises from widely valid scaling\nproperties of the con ning potential. Gaussian Quantum dots having N = 2, 5 and\n8 electrons are particularly stable in agreement with Hund rule. The shell\nstructure becomes less and less noticeable as the well radius increases.",
        "positive": "Quantum anomalies in nodal line semimetals: Topological semimetals is a new class of condensed matter systems with\nnontrivial electronic structure topology. Their unusual observable properties\nmay often be understood in terms of quantum anomalies. In particular, Weyl and\nDirac semimetals, which have point band touching nodes, are characterized by\nthe chiral anomaly, which leads to the Fermi arc surface states, anomalous Hall\neffect, negative longitudinal magnetoresistance and planar Hall effect. In this\npaper we explore analogous phenomena in nodal line semimetals. We demonstrate\nthat such semimetals realize a three dimensional analog of the parity anomaly,\nwhich is a known property of two dimensional Dirac semimetals arising, for\nexample, on the surface of a three dimensional topological insulator. We relate\none of the characteristic properties of nodal line semimetals, namely the\ndrumhead surface states, to this anomaly, and derive the field theory, which\nencodes the corresponding anomalous response."
    },
    {
        "anchor": "Asymmetry of non-local dissipation: From drift-diffusion to\n  hydrodynamics: We study dissipation in inhomogeneous two-dimensional electron systems. We\npredict a relatively strong current-induced spatial asymmetry in the heating of\nthe electron and phonon systems -- even if the inhomogeneity responsible for\nthe electrical resistance is symmetric with respect to the current direction.\nWe also show that the heat distributions in the hydrodynamic and\nimpurity-dominated limits are essentially different. In particular, within a\nwide, experimentally relevant interval of driving fields, the dissipation\nprofile in the hydrodynamic limit turns out to be asymmetric, and the\ncharacteristic spatial scale of the temperature distribution can be controlled\nby the driving field. By contrast, in the same range of parameters,\nimpurity-dominated heating is almost symmetric, with the size of the\ndissipation region being independent of the field. This allows one to\ndistinguish experimentally the hydrodynamic and impurity-dominated limits. Our\nresults are consistent with recent experimental findings on transport and\ndissipation in narrow constrictions and quantum point contacts.",
        "positive": "GaTe-Assisted CVD Growth of Ultrathin Large-Scale 2D Ferromagnetic\n  Cr5Te8: Recently, 2D Cr5Te8 has been successfully synthesized experimentally and has\nattracted widespread research interest due to its intriguing magnetic\nproperties, such as hard magnetism with strong perpendicular anisotropy.\nHowever, exploring new methods for growing ultrathin 2D Cr5Te8 with a larger\nscale and their controllable synthesis remain challenging. Herein, the\nsynthesis of ultrathin 2D ferromagnetic Cr5Te8 nanosheets by chemical vapor\ndeposition (CVD) using GaTe as growth source is reported, whose size is up to\n~160 {\\mu}m and the thickness is lower to only 5 nm. The GaTe promotes the\nconcentration of effective Te atoms to facilitate the direction of the\nsynthesis reaction, enabling the rapid lateral growth rate. As a result, the\nsynthesis of ultrathin, large-scale 2D ferromagnetic Cr5Te8 was achieved. By\nprecisely adjusting the growth temperature and the source-substrate distance\n(Dss), the lateral size of the Cr5Te8 nanosheets can be tuned from a few to\n~164 {\\mu}m. Furthermore, magnetic property measurement system (MPMS) suggested\nthat Cr5Te8 nanosheets possess intense out-of-plane ferromagnetism and the\nCurie temperature exhibits a monotonic increase from 163 to 175 K as the Cr5Te8\nthickness. This work not only paves a way for the controllable growth of\nultrathin, large-scale 2D ferromagnetic crystalline, but also provides a new\nplatform for the spintronics and the practical application of magnetic memory\ndevices."
    },
    {
        "anchor": "Indirect control of spin precession by electric field via spin-orbit\n  coupling: The spin-orbit coupling (SOC) can mediate electric-dipole spin resonance\n(EDSR) in an a.c. electric field. In this letter, the EDSR is essentially\nunderstood as an spin precession under an effective a.c. magnetic field induced\nby the SOC in the reference frame, which is exactly following the classical\ntrajectory of the electron and obtained by applying a quantum linear coordinate\ntransformation. With this observation for one-dimensional (1D) case, we find a\nupper limit for the spin-flipping speed in the EDSR-based control of spin,\nwhich is given by the accessible data from the current experiment. For\ntwo-dimensional case, the azimuthal dependence of the effective magnetic field\ncan be used to measure the ratio of the Rashba and Dresselhause SOC strengths.",
        "positive": "Universal Fluctuations and Coherence Lengths in Chaotic Mesoscopic\n  Systems and Nuclei: We discuss the phenomenon of universal fluctuations in mesoscopic systems and\nnuclei. For this purpose we use Random Matrix Theory (RMT). The statistical\n$S$-matrix is used to obtain the physical observables in the case of Quantum\nDots, both the Schr\\\"odinger and the Dirac types. To obtain analytical results,\nwe use the Stub model. In all cases we concentrate our attention on the average\ndensity of maxima in the fluctuating observables, such as the electronic\nconductance. The case of neutron capture by a variety of nuclei at thermal\nenergies is also considered. Here the average density of maxima in the cross\nsection vs. the mass number is analysed and traced to astrophysical conditions."
    },
    {
        "anchor": "Chronological-safe kind of geometric phase for $C_{60}$ fullerenes in\n  G\u00f6del spacetimes: In this paper, we investigate a rotating fullerene molecule with Ih symmetry\nwithin the framework of non-inertial spacetimes. We use a low-energy geometric\ntheory to describe the molecule as a two-dimensional spherical space of G\\\"odel\ntype. Using the well-known fictitious `t Hooft Polyakov monopole to decouple\nthe doublet associated with the lattice, we employ the Dirac factor method to\nderive a geometric phase for the fermions in the system. We also discuss the\nchronology protection feature of the phase through specific geometric\nconsiderations for the system.",
        "positive": "Stimulated Phonon Emission in a Driven Double Quantum Dot: The compound semiconductor gallium arsenide (GaAs) provides an ultra-clean\nplatform for storing and manipulating quantum information, encoded in the\ncharge or spin states of electrons confined in nanostructures. The absence of\ninversion symmetry in the zinc-blende crystal structure of GaAs however,\nresults in strong piezoelectric coupling between lattice acoustic phonons and\nelectrons, a potential hindrance for quantum computing architectures that can\nbe charge-sensitive during certain operations. Here we examine phonon\ngeneration in a GaAs double dot, configured as a single- or two-electron charge\nqubit, and driven by the application of microwaves via surface gates. In a\nprocess that is a microwave analog of the Raman effect, stimulated phonon\nemission is shown to produce population inversion of a two-level system and\nprovides spectroscopic signatures of the phononic environment created by the\nnanoscale device geometry."
    },
    {
        "anchor": "Probing variations of the Rashba spin-orbit coupling at the nanometer\n  scale: The Rashba effect as an electrically tunable spin-orbit interaction is the\nbase for a multitude of possible applications such as spin filters, spin\ntransistors, and quantum computing using Majorana states in nanowires.\nMoreover, this interaction can determine the spin dephasing and\nantilocalization phenomena in two dimensions. However, the real space pattern\nof the Rashba parameter has never been probed, albeit it critically influences,\ne.g., the more robust spin transistors using the spin helix state and the\notherwise forbidden electron backscattering in topologically protected\nchannels. Here, we map this pattern down to nanometer length scales by\nmeasuring the spin splitting of the lowest Landau level using scanning\ntunnelling spectroscopy. We reveal strong fluctuations correlated with the\nlocal electrostatic potential for an InSb inversion layer with a large Rashba\ncoefficient (~1 eV{\\AA}). The novel type of Rashba field mapping enables a more\ncomprehensive understanding of the critical fluctuations, which might be\ndecisive towards robust semiconductor-based spintronic devices.",
        "positive": "Excitonic Instabilities and Insulating States in Bilayer Graphene: The competing ground states of bilayer graphene are studied by applying\nrenormalization group techniques to a bilayer honeycomb lattice with nearest\nneighbor hopping. In the absence of interactions, the Fermi surface of this\nmodel at half-filling consists of two nodal points with momenta $\\mathbf{K}$,\n$\\mathbf{K}'$, where the conduction band and valence band touch each other,\nyielding a semi-metal. Since near these two points the energy dispersion is\nquadratic with perfect particle-hole symmetry, excitonic instabilities are\ninevitable if inter-band interactions are present. Using a perturbative\nrenormalization group analysis up to the one-loop level, we find different\ncompeting ordered ground states, including ferromagnetism, superconductivity,\nspin and charge density wave states with ordering vector\n$\\mathbf{Q}=\\mathbf{K}-\\mathbf{K}'$, and excitonic insulator states. In\naddition, two states with valley symmetry breaking are found in the excitonic\ninsulating and ferromagnetic phases. This analysis strongly suggests that the\nground state of bilayer graphene should be gapped, and with the exception of\nsuperconductivity, all other possible ground states are insulating."
    },
    {
        "anchor": "Square-root topological semimetals: We propose topological semimetals generated by the square-root operation for\ntight-binding models in two and three dimensions, which we call square-root\ntopological semimetals. The square-root topological semimetals host topological\nband touching at finite energies, whose topological protection is inherited\nfrom the squared Hamiltonian. Such a topological character is also reflected in\nemergence of boundary modes with finite energies. Specifically, focusing on\ntopological properties of squared Hamiltonian in class AIII, we reveal that a\ndecorated honeycomb (decorated diamond) model hosts finite-energy Dirac cones\n(nodal lines). We also propose a realization of a square-root topological\nsemimetal in a spring-mass model, where robustness of finite-energy Dirac\npoints against the change of tension is elucidated.",
        "positive": "Modeling electronic, mechanical, optical and thermal properties of\n  graphene-like BC$_6$N materials: Role of prominent BN-bonds: We model monolayer graphene-like materials with BC$_6$N stoichiometry where\nthe bonding between the B and the N atoms plays an important role for their\nphysical and chemical properties. Two types of BC$_6$N are found based on the\nBN bonds: In the presence of BN bonds, an even number of $\\pi$-bonds emerges\nindicating an aromatic structure and a large direct bandgap appears, while in\nthe absence of BN bonds, an anti-aromatic structure with an odd-number of\n$\\pi$-bonds is found resulting a direct small bandgap. The stress-strain curves\nshows high elastic moduli and tensile strength of the structures with BN-bonds,\ncompared to structures without BN-bonds. Self-consistent field calculations\ndemonstrate that BC$_6$N with BN-bonds is energetically more stable than\nstructures without BN-bonds due to a strong binding energy between the B and\nthe N atoms, while their phonon dispersion displays that BC$_6$N without\nBN-bonds has more dynamical stability. Furthermore, all the BC$_6$N structures\nconsidered show a large absorption of electromagnetic radiation with\npolarization parallel to the monolayers in the visible range. Finer detail of\nthe absorption depend on the actual structures of the layers. A higher\nelectronic thermal conductivity and specific heat are seen in BC$_6$N systems\ncaused by hot carrier--assisted charge transport. This opens up a possible\noptimization for bolometric applications of graphene based material devices."
    },
    {
        "anchor": "Non-Reciprocal Spin Pumping in Asymmetric Magnetic Trilayers: In magnetic trilayer systems, spin pumping is generally addressed as a\nreciprocal mechanism characterized by one unique spin mixing conductance common\nto both interfaces. However, this assumption is questionable in cases where\ndifferent types of interfaces are present in the material. Here, we present a\ngeneral theory for analyzing spin pumping in cases with more than one unique\ninterface. The theory is applied to analyze layer-resolved ferromagnetic\nresonance experiments on the trilayer system\nNi$_{20}$Fe$_{80}$/Ru/Fe$_{49}$Co$_{49}$V$_2$ where the Ru spacer thickness is\nvaried to tune the indirect exchange coupling. The results show that the spin\npumping in trilayer systems with dissimilar magnetic layers is non-reciprocal,\nwith a surprisingly large difference between spin-pumping induced damping of\ndifferent interfaces. Our findings have importance on dynamics of spintronic\ndevices based on magnetic multilayer materials.",
        "positive": "Analytical model of 1D Carbon-based Schottky-Barrier Transistors: Nanotransistors typically operate in far-from-equilibrium (FFE) conditions,\nthat cannot be described neither by drift-diffusion, nor by purely ballistic\nmodels. In carbonbased nanotransistors, source and drain contacts are often\ncharacterized by the formation of Schottky Barriers (SBs), with strong\ninfluence on transport. Here we present a model for onedimensional field-effect\ntransistors (FETs), taking into account on equal footing both SB contacts and\nFFE transport regime. Intermediate transport is introduced within the Buttiker\nprobe approach to dissipative transport, in which a non-ballistic transistor is\nseen as a suitable series of individually ballistic channels. Our model permits\nthe study of the interplay of SBs and ambipolar FFE transport, and in\nparticular of the transition between SB-limited and dissipation-limited\ntransport."
    },
    {
        "anchor": "Relaxation-limited electronic currents in extended reservoir simulations: Open-system approaches are gaining traction in the simulation of charge\ntransport in nanoscale and molecular electronic devices. In particular,\n\"extended reservoir\" simulations, where explicit reservoir degrees of freedom\nare present, allow for the computation of both real-time and steady-state\nproperties but require relaxation of the extended reservoirs. The strength of\nthis relaxation, $\\gamma$, influences the conductance, giving rise to a\n\"turnover\" behavior analogous to Kramers' turnover in chemical reaction rates.\nWe derive explicit, general expressions for the weak and strong relaxation\nlimits. For weak relaxation, the conductance increases linearly with $\\gamma$\nand every electronic state of the total explicit system contributes to the\nelectronic current according to its \"reduced\" weight in the two extended\nreservoir regions. Essentially, this represents two conductors in series -- one\nat each interface with the implicit reservoirs that provide the relaxation. For\nstrong relaxation, a \"dual\" expression -- one with the same functional form --\nresults, except now proportional to $1/\\gamma$ and dependent on the system of\ninterest's electronic states, reflecting that the strong relaxation is\nlocalizing electrons in the extended reservoirs. Higher order behavior (e.g.,\n$\\gamma^2$ or $1/\\gamma^2$) can occur when there is a gap in the frequency\nspectrum. Moreover, inhomogeneity in the frequency spacing can give rise to a\npseudo-plateau regime. These findings yield a physically motivated approach to\ndiagnosing numerical simulations and understanding the influence of relaxation,\nand we examine their occurrence in both simple models and a realistic,\nfluctuating graphene nanoribbon.",
        "positive": "Evolution of Landau Levels into Edge States at an Atomically Sharp Edge\n  in Graphene: The quantum-Hall-effect (QHE) occurs in topologically-ordered states of\ntwo-dimensional (2d) electron-systems in which an insulating bulk-state\ncoexists with protected 1d conducting edge-states. Owing to a unique\ntopologically imposed edge-bulk correspondence these edge-states are endowed\nwith universal properties such as fractionally-charged quasiparticles and\ninterference-patterns, which make them indispensable components for QH-based\nquantum-computation and other applications. The precise edge-bulk\ncorrespondence, conjectured theoretically in the limit of sharp edges, is\ndifficult to realize in conventional semiconductor-based electron systems where\nsoft boundaries lead to edge-state reconstruction. Using scanning-tunneling\nmicroscopy and spectroscopy to follow the spatial evolution of bulk\nLandau-levels towards a zigzag edge of graphene supported above a graphite\nsubstrate we demonstrate that in this system it is possible to realize\natomically sharp edges with no edge-state reconstruction. Our results single\nout graphene as a system where the edge-state structure can be controlled and\nthe universal properties directly probed."
    },
    {
        "anchor": "Electrical control of lifetime-limited quantum emitters using 2D\n  materials: Solid state quantum emitters are a mainstay of quantum nanophotonics as\nintegrated single photon sources (SPS) and optical nanoprobes. Integrating such\nemitters with active nanophotonic elements is desirable in order to attain\nefficient control of their optical properties but typically degrades the\nphotostability of the emitter itself. Here, we demonstrate a tuneable hybrid\ndevice that integrates lifetime-limited single emitters (linewidth : 40 MHz)\nand 2D materials at sub-wavelength separation without degradation of the\nemission properties. Our device s nanoscale dimensions enable ultra-broadband\ntuning (tuning range larger than 400 GHz) and fast modulation (frequency : 100\nMHz) of the emission energy, which renders it an integrated, ultra-compact\ntuneable SPS. Conversely, this offers a novel approach to optical sensing of 2D\nmaterial properties using a single emitter as a nanoprobe.",
        "positive": "Current induced generation and synchronous motion of highly packed\n  coupled chiral domain walls: Chiral domain walls of Neel type emerge in heterostructures that include\nheavy metal (HM) and ferromagnetic metal (FM) layers owing to the\nDzyaloshinskii-Moriya (DM) interaction at the HM/FM interface. In developing\nstorage class memories based on the current induced motion of chiral domain\nwalls, it remains to be seen how dense such domain walls can be packed\ntogether. Here we show that a universal short range repulsion that scales with\nthe strength of the DM interaction exists among chiral domain walls. The\ndistance between the two walls can be reduced with application of out of plane\nfield, allowing formation of coupled domain walls. Surprisingly, the current\ndriven velocity of such coupled walls is independent of the out of plane field,\nenabling manipulation of significantly compressed coupled domain walls using\ncurrent pulses. Moreover, we find that a single current pulse with optimum\namplitude can create a large number of closely spaced domain walls. These\nfeatures allow current induced generation and synchronous motion of highly\npacked chiral domain walls, a key feature essential for developing domain wall\nbased storage devices."
    },
    {
        "anchor": "Quasiparticle scattering and local density of states in graphite: We determine the effect of quasiparticle interference on the spatial\nvariations of the local density of states (LDOS) in graphite in the\nneighborhood of an isolated impurity. A number of characteristic behaviors of\ninterference are identified in the Fourier transformed spectrum. A comparison\nbetween our results and scanning tunneling microscopy (STM) experiments could\nprovide a critical test of the range (of energy) of applicability of the Fermi\nliquid description of graphite, where some evidence of the breakdown of Fermi\nliquid theory has recently been discussed. Moreover, given the similarity\nbetween the band structures of graphite and that of nodal quasiparticles in a\nd-wave superconductor, a comparison between results in the two materials is\nuseful for understanding the physics of the cuprates.",
        "positive": "Stability limits of elemental 2D metals in graphene pores: Two-dimensional (2D) materials can be used as stabilizing templates for\nexotic nanostructures, including pore-stabilized, free-standing patches of\nelemental metal monolayers. Although these patches represent metal clusters\nunder extreme conditions and are thus bound for investigations, they are poorly\nunderstood as their energetic stability trends and the most promising elements\nremain unknown. Here, using density-functional theory simulations and liquid\ndrop model to explore the properties of 45 elemental metal candidates, we\nidentify metals that enable the largest and most stable patches. Simulations\nshow that pores can stabilize patches up to $\\sim 8$ nm$^2$ areas and that the\nmost prominent candidate in a graphene template is Cu. The results, which are\ngeneralizable to templates also beyond graphene, provide encouragement for\nfurther, even more resolute experimental pursuit of 2D metals."
    },
    {
        "anchor": "Carrier separation in type II quantum dots inserted in (Zn,Mg)Te/ZnSe\n  nanowire: Quantum dots consisting of an axial Zn0.97Mg0.03Te insertion inside a large\nbandgap Zn0.9Mg0.1Te nanowire cores are fabricated in a molecular beam epitaxy\nsystem by employing the vapor-liquid-solid growth mechanism. Additionally, this\nstructure is coated with a thin ZnSe radial shell which forms type II interface\nwith the dot semiconductor. The resulting radial electron-hole separation is\nevidenced by several distinct effects which occur in the presence of ZnSe\nshell, including: the optical emission redshift of about 250 meV, a significant\ndecrease of the emission intensity, the increase of the excitonic lifetime by\none order of magnitude and the increase of the biexciton binding energy. The\ntype II nanowire quantum dots where electrons and holes are radially separated\nconstitute a promising platform for potential applications in the field of\nquantum information technology.",
        "positive": "Photocurrent measurements in topological insulator\n  $\\text{Bi}_2\\text{Se}_3$ nanowires: Circular photogalvanic currents are a promising new approach for\nspin-optoelectronics. To date, such currents have only been induced in\ntopological insulator flakes or extended films. It is not clear whether they\ncan be generated in nanodevices. In this paper, we demonstrate the generation\nof circular photogalvanic currents in $\\text{Bi}_2\\text{Se}_3$ nanowires. Each\nnanowire shows topological surface states. Here, we generate and distinguish\nthe different photocurrent contributions via the driving light wave. We\nseparate the circular photogalvanic currents from those due to thermal Seebeck\neffects, through controlling the laser light polarization. The results reveal a\nspin-polarized surface-Dirac electron flow in the nanowires arising from\nspin-momentum locking and spin-orbit effects. The second photocurrent\ncontribution described in this letter is caused by the thermal Seebeck effect.\nBy scanning the photocurrent, it can be spatially resolved; upon reversing the\ngradient direction along the nanowire, the photocurrent changes its sign, and\nclose to the gold contacts, the amplitudes of the different photocurrent\ncontributions are affected by the proximity to the contacts. In the center of\nthe nanowires, where the effects from the gold contact/ topological insulator\nstacks vanish, the spin-polarized current remains constant along the nanowires.\nThis opens up a new method of all-optical spin current generation in\ntopological insulator nanowires and hybrid structures for nanoscale\nspin-orbitronics."
    },
    {
        "anchor": "Tight-Binding Model and Electronic Property of Dirac Nodal Line in\n  Single-Component Molecular Conductor [Pt(dmdt)$_{2}$]: Motivated by the recent discovery of Dirac nodal line in the single-component\nmolecular conductor [Pt(dmdt)$_{2}$], we propose a three-orbital tight-binding\nmodel based on the Wannier fitting of the first-principles calculation, and\naddress the problems of edge states, topological properties and magnetic\nsusceptibility. We find that logarithmic peaks of the local density of states\nemerge near the Fermi energy, owing to pseudo-one-dimensional edge states that\nappear between the Dirac nodal lines. Magnetic susceptibility calculated in our\nmodel can explain the experimental result at a high temperature. In the\npresence of a realistic spin-orbit coupling, we show that [Pt(dmdt)$_{2}$] is a\ntopological nodal line semimetal with isolated electron and hole pockets.",
        "positive": "Defects in Graphene : A Topological Description: Specific types of spatial defects or potentials can turn monolayer graphene\ninto a topological material. These topological defects are classified by a\nspatial dimension $D$ and they are systematically obtained from the Hamiltonian\nby means of its symbol $\\mathcal{H} (\\boldsymbol{k}, \\boldsymbol{r}) $, an\noperator which generalises the Bloch Hamiltonian and contains all topological\ninformation. This approach, when applied to Dirac operators, allows to recover\nthe tenfold classification of insulators and superconductors. The existence of\na stable $\\mathbb{Z}$-topology is predicted as a condition on the dimension\n$D$, similar to the classification of defects in thermodynamic phase\ntransitions. Kekule distortions, vacancies and adatoms in graphene are proposed\nas examples of such defects and their topological equivalence is discussed."
    },
    {
        "anchor": "Backscattering Between Helical Edge States via Dynamic Nuclear\n  Polarization: We show that that the non-equilibrium spin polarization of one dimensional\nhelical edge states at the boundary of a two dimensional topological insulator\ncan dynamically induce a polarization of nuclei via the hyperfine interaction.\nWhen combined with a spatially inhomogeneous Rashba coupling, the steady state\npolarization of the nuclei produces backscattering between the topologically\nprotected edge states leading to a reduction in the conductance which persists\nto zero temperature. We study these effects in both short and long edges,\nuncovering deviations from Ohmic transport at finite temperature and a current\nnoise spectrum which may hold the fingerprints for experimental verification of\nthe backscattering mechanism.",
        "positive": "Emergent $Z_2$ Topological Invariant and Robust Helical Edge States in\n  Two-Dimensional Topological Metals: In this work, we study the disorder effect on topological metals that support\na pair of helical edge modes deeply embedded inside the gapless bulk states.\nStrikingly, we predict that a quantum spin Hall (QSH) phase can be obtained\nfrom such topological metals without opening a global band gap. To be specific,\ndisorder can lead to a pair of robust helical edge states which is protected by\nan emergent $Z_2$ topological invariant, giving rise to a quantized conductance\nplateau in transport measurements. These results are instructive for solving\npuzzles in {various transport experiments on QSH materials} that are\nintrinsically metallic. This work also will inspire experimental realization of\nthe QSH effect in disordered topological metals."
    },
    {
        "anchor": "Machine learning nonequilibrium electron forces for adiabatic spin\n  dynamics: We present a generalized potential theory of nonequilibrium torques for the\nLandau-Lifshitz equation. The general formulation of exchange forces in terms\nof two potential energies allows for the implementation of accurate machine\nlearning models for adiabatic spin dynamics of out-of-equilibrium itinerant\nmagnetic systems. To demonstrate our approach, we develop a deep-learning\nneural network that successfully learns the forces in a driven s-d model\ncomputed from the nonequilibrium Green's function method. We show that the\nLandau-Lifshitz dynamics simulations with forces predicted from the neural-net\nmodel accurately reproduce the voltage-driven domain-wall propagation. Our work\nopens a new avenue for multi-scale modeling of nonequilibrium dynamical\nphenomena in itinerant magnets and spintronics based on machine-learning\nmodels.",
        "positive": "Current induced electron spin polarization in strained semiconductors: The polarization of conduction electron spins due to an electrical current is\nobserved in strained nonmagnetic semiconductors using static and time-resolved\nFaraday rotation. The density, lifetime, and orientation rate of the\nelectrically-polarized spins are characterized by a combination of optical and\nelectrical methods. In addition, the dynamics of the current-induced spins are\ninvestigated by utilizing electrical pulses generated from a photoconductive\nswitch. These results demonstrate the possibility of a spin source for\nsemiconductor spintronic devices without the use of magnetic materials."
    },
    {
        "anchor": "Probing one-dimensional systems via noise magnetometry with single spin\n  qubits: The study of exotic one-dimensional states, particularly those at the edges\nof topological materials, demand new experimental probes that can access the\ninterplay between charge and spin degrees of freedom. One potential approach is\nto use a single spin probe, such as a Nitrogen Vacancy center in diamond, which\nhas recently emerged as a versatile tool to probe nanoscale systems in a\nnon-invasive fashion. Here we present a theory describing how noise\nmagnetometry with spin probes can directly address several questions that have\nemerged in experimental studies of 1D systems, including those in topological\nmaterials. We show that by controlling the spin degree of freedom of the probe,\nit is possible to measure locally and independently local charge and spin\ncorrelations of 1D systems. Visualization of 1D edge states, as well as\nsampling correlations with wavevector resolution can be achieved by tuning the\nprobe-to-sample distance. Furthermore, temperature-dependent measurements of\nmagnetic noise can clearly delineate the dominant scattering mechanism\n(impurities vs. interactions) -- this is of particular relevance to quantum\nspin Hall measurements where conductance quantization is not perfect. The\npossibility to probe both charge and spin excitations in a wide range of length\nscales opens new pathways to bridging the large gap between atomic scale\nresolution of scanning probes and global transport measurements.",
        "positive": "Topological Zero-Line Modes in Folded Bilayer Graphene: We theoretically investigate a folded bilayer graphene structure as an\nexperimentally realizable platform to produce the one-dimensional topological\nzero-line modes. We demonstrate that the folded bilayer graphene under an\nexternal gate potential enables tunable topologically conducting channels to be\nformed in the folded region, and that a perpendicular magnetic field can be\nused to enhance the conducting when external impurities are present. We also\nshow experimentally that our proposed folded bilayer graphene structure can be\nfabricated in a controllable manner. Our proposed system greatly simplifies the\ntechnical difficulty in the original proposal by considering a planar bilayer\ngraphene (i.e., precisely manipulating the alignment between vertical and\nlateral gates on bilayer graphene), laying out a new strategy in designing\npractical low-power electronics by utilizing the gate induced topological\nconducting channels."
    },
    {
        "anchor": "How composite bosons really interact: The aim of this paper is to clarify the conceptual difference which exists\nbetween the interactions of composite bosons and the interactions of elementary\nbosons. A special focus is made on the physical processes which are missed when\ncomposite bosons are replaced by elementary bosons. Although what is here said\ndirectly applies to excitons, it is also valid for bosons in other fields than\nsemiconductor physics. We in particular explain how the two basic scatterings\n-- Coulomb and Pauli -- of our many-body theory for composite excitons can be\nextended to a pair of fermions which is not an Hamiltonian eigenstate -- as for\nexample a pair of trapped electrons, of current interest in quantum\ninformation.",
        "positive": "Induced by coherent THz-radiation high harmonics generation in bilayer\n  graphene at high Fermi energies: The higher order harmonic generation process in the nonperturbative regime at\nthe interaction of coherent electromagnetic radiation with the AB-stacked\nbilayer graphene at high Fermi energies is considered. The applied coherent\nlow-frequency radiation field in the high Fermi energy zone of electrons\nexcludes the interband transitions enhancing high harmonic rates. The developed\nmicroscopic nonlinear quantum theory for charged carriers interaction with a\nstrong pump wave is valid near the Dirac points of the Brillouin zone. The\nLiouville-von Neumann equation for the density matrix in the multiphoton\nexcitation regime is solved both analytically and numerically. Based on the\nnumerical solutions, we examine the rates of higher-order harmonics of the pump\nwave of arbitrary polarization. Obtained results show that bilayer graphene can\nserve as an effective material for the generation of higher-order harmonics\nfrom THz to the mid-IR domain of frequencies at the pump wave moderate\nintensities."
    },
    {
        "anchor": "Relevance of Shockley states on the electrical and thermoelectric\n  response of gold-based single-molecule junctions: Noble metals break preferably exposing (111)-oriented surfaces, that host\nShockley type surface states (SSs). Nevertheless, the relevance of SSs on the\nelectrical properties of gold-based molecular junctions has not been explored\nin detail yet. Here, we present ab initio simulations that show how the gold\n(111) SS, that lies approximately 0.5 eV below the Fermi energy, is key to\ndetermining correctly the electrical and thermoelectric response of the above\njunctions. We show how the ability to shift in a controlled way the energy\nposition of gold SS enables us to tune the electrical and thermoelectric\nresponse of gold molecular junctions. We also show that gold's SS appears in\nour simulations only if the 5d orbitals are included explicitly in the valence\nshell. To illustrate this behaviour, we discuss in detail Benzenediamine (BDA)\nand Benzenedicarbonitrile (BDCN) gold (111) junctions.",
        "positive": "Optical switching of electron transport in a waveguide-QED system: Electron switching in waveguides coupled to a photon cavity is found to be\nstrongly influenced by the photon energy and polarization. Therefore, the\ncharge dynamics in the system is investigated in two different regimes, for\noff- and on-resonant photon fields. In the off-resonant photon field, the\nphoton energy is smaller than the energy spacing between the first two lowest\nsubbands of the waveguide system, the charge splits between the waveguides\nimplementing a $\\sqrt{\\rm NOT}$-quantum logic gate action. In the on-resonant\nphoton field, the charge is totally switched from one waveguide to the other\ndue to the appearance of photon replica states of the first subband in the\nsecond subband region instigating a quantum-NOT transition.In addition, the\nimportance of the photon polarization to control the charge motion in the\nwaveguide system is demonstrated.The idea of charge switching in electronic\ncircuits may serve to built quantum bits."
    },
    {
        "anchor": "Direct observation of low frequency confined acoustic phonons in silver\n  nanoparticles: Terahertz time domain spectroscopy: Terahertz time domain spectroscopy has been used to study low frequency\nconfined acoustic phonons of silver nanoparticles embedded in poly(vinyl\nalcohol) matrix in the spectral range of 0.1 to 2.5 THz. The real and imaginary\nparts of the dielectric function show two bands at 0.60 THz and 2.12 THz\nattributed to the spheroidal and toroidal modes of silver nanoparticles, thus\ndemonstrating the usefulness of terahertz time domain spectroscopy as a\ncomplementary technique to Raman spectroscopy in characterizing the\nnanoparticles.",
        "positive": "Kwant: a software package for quantum transport: Kwant is a Python package for numerical quantum transport calculations. It\naims to be an user-friendly, universal, and high-performance toolbox for the\nsimulation of physical systems of any dimensionality and geometry that can be\ndescribed by a tight-binding model. Kwant has been designed such that the\nnatural concepts of the theory of quantum transport (lattices, symmetries,\nelectrodes, orbital/spin/electron-hole degrees of freedom) are exposed in a\nsimple and transparent way: Defining a new simulation setup is very close to\ndescribing the corresponding mathematical model. Kwant offers direct support\nfor calculations of transport properties (conductance, noise, scattering\nmatrix), dispersion relations, modes, wave functions, various Green's\nfunctions, and out-of-equilibrium local quantities. Other computations\ninvolving tight-binding Hamiltonians can be implemented easily thanks to its\nextensible and modular nature. Kwant is free software available at\nhttp://kwant-project.org/."
    },
    {
        "anchor": "Non-universal suppression of the excitation gap in chaotic Andreev\n  billiards: Superconducting terminals as sensitive probes for scarred states: When a quantum-chaotic normal conductor is coupled to a superconductor,\nrandom-matrix theory predicts that a gap opens up in the excitation spectrum\nwhich is of universal size $E_g^{\\rm RMT}\\approx 0.3 \\hbar/t_D$, where $t_D$ is\nthe mean scattering time between Andreev reflections. We show that a scarred\nstate of long lifetime $t_S\\gg t_D$ suppresses the excitation gap over a window\n$\\Delta E\\approx 2 E_g^{\\rm RMT}$ which can be much larger than the narrow\nresonance width $\\Gamma_S=\\hbar/t_S$ of the scar in the normal system. The\nminimal value of the excitation gap within this window is given by\n$\\Gamma_S/2\\ll E_g^{\\rm RMT}$. Hence the scarred state can be detected over a\nmuch larger energy range than it is the case when the superconducting terminal\nis replaced by a normal one.",
        "positive": "Room Temperature Terahertz Electroabsorption Modulation by Excitons in\n  Monolayer Transition Metal Dichalcogenides: The interaction between off-resonant laser pulses and excitons in monolayer\ntransition metal dichalcogenides is attracting increasing interest as a route\nfor the valley-selective coherent control of the exciton properties. Here, we\nextend the classification of the known off-resonant phenomena by unveiling the\nimpact of a strong THz field on the excitonic resonances of monolayer MoS$_2$.\nWe observe that the THz pump pulse causes a selective modification of the\ncoherence lifetime of the excitons, while keeping their oscillator strength and\npeak energy unchanged. We rationalize these results theoretically by invoking a\nhitherto unobserved manifestation of the Franz-Keldysh effect on an exciton\nresonance. As the modulation depth of the optical absorption reaches values as\nlarge as 0.05 dB/nm at room temperature, our findings open the way to the use\nof semiconducting transition metal dichalcogenides as compact and efficient\nplatforms for high-speed electroabsorption devices."
    },
    {
        "anchor": "Large orbital magnetic moments in carbon nanotubes generated by resonant\n  transport: The nonequilibrium Green's function method is used to study the ballistic\ntransport in metallic carbon nanotubes when a current is injected from the\nelectrodes with finite bias voltages. We reveal, both analytically and\nnumerically, that large loop currents circulating around the tube are induced,\nwhich come from a quantum mechanical interference and are much larger than the\ncurrent along the tube axis when the injected electron is resonant with a\ntime-reversed pair of degenerate states, which are, in fact, inherent in the\nzigzag and chiral nanotubes. This results in large orbital magnetic moments,\nmaking the nanotube a molecular solenoid.",
        "positive": "Dimensionality and Anisotropicity Dependence of Radiative Recombination\n  in Nanostructured Phosphorene: The interplay between dimensionality and anisotropicity leads to intriguing\noptoelectronic properties and exciton dynamics in low dimensional\nsemiconductors. In this study we use nanostructured phosphorene as a\nprototypical example to unfold such complex physics and develop a general\nfirst-principles framework to study exciton dynamics in low dimensional\nsystems. Specifically we derived the radiative lifetime and light emission\nintensity from 2D to 0D systems based on many-body perturbation theory, and\ninvestigated the dimensionality and anisotropicity effects on radiative\nrecombination lifetime both at 0 K and finite temperature, as well as\npolarization and angle dependence of emitted light. We show that the radiative\nlifetime at 0 K increases by an order of $10^3$ with the lowering of one\ndimension (i.e. from 2D to 1D nanoribbons or from 1D to 0D quantum dots). We\nalso show that obtaining the radiative lifetime at finite temperature requires\naccurate exciton dispersion beyond the effective mass approximation. Finally,\nwe demonstrate that monolayer phosphorene and its nanostructures always emit\nlinearly polarized light consistent with experimental observations, different\nfrom in-plane isotropic 2D materials like MoS2 and h-BN that can emit light\nwith arbitrary polarization, which may have important implications for quantum\ninformation applications."
    },
    {
        "anchor": "Crossover from Room-temperature Double-channel Ballistic Transport to\n  Single-channel Ballistic Transport in Zigzag Graphene Nanoribbons: Very recently, it was demonstrated explicitly that a zigzag graphene\nnanoribbon (GNR) exhibits a crossover of conductance from G0 to G0/2 with\nincreasing the length (G0 = 2e2/h is the quantum of conductance) even at\nroom-temperature [Baringhaus, et al. Nature 506, 349 (2014)]. Such a result is\npuzzling as none of previous theories seem to match the experimental\nobservations. Here, we propose a model to explain the crossover from\ndouble-channel to single-channel ballistic transport in zigzag GNR. The sp3\ndistortion of carbon atoms at the GNR edges induces a large spin-orbit coupling\non the edges atoms, which enhances spin-flip scattering of edge states of the\nzigzag GNR. With sufficient spin-flip scattering, the wave-function of edge\nstates becomes a superposition of the spin-up and spin-down components. Then\nthe coupling of the two edges becomes important. This removes the edge degree\nof freedom in the zigzag GNR and results in the evolution of the conductance\nfrom G0 to G0/2 with increasing the length.",
        "positive": "Anisotropic exchange coupling in a nanowire double quantum dot with\n  strong spin-orbit coupling: A spin-orbit qubit is a hybrid qubit that contains both orbital and spin\ndegrees of freedom of an electron in a quantum dot. Here we study the exchange\ncoupling between two spin-orbit qubits in a nanowire double quantum dot (DQD)\nwith strong spin-orbit coupling (SOC). We find that while the total tunneling\nin the DQD is irrelevant to the SOC, both the spin-conserved and spin-flipped\ntunnelings are SOC dependent and can compete with each other in the strong SOC\nregime. Moreover, the Coulomb repulsion between electrons can combine with the\nSOC-dependent tunnelings to yield an anisotropic exchange coupling between the\ntwo spin-orbit qubits. Also, we give an explicit physical mechanism for this\nanisotropic exchange coupling."
    },
    {
        "anchor": "Change in Stacking Order and Lifshitz transition in Bi-layer Graphene: We consider the AB-(Bernal) stacking for the bi-layer graphene (BLG) system\nand assume that a perpendicular electric field is created by the external gates\ndeposited on the BLG surface. In the basis (A1, B2, A2, B1) for the valley K\nand the basis (B2, A1, B1, A2) for the valley K', we show the occurrence of\ntrigonal warping [ see A. S. N\\'u\\~nez et al.,arXiv:1012.4318], that is,\nsplitting of the energy bands or the density of states on the kx - ky plane\ninto four pockets comprising of the central part and three legs due to a (skew)\ninterlayer hopping between A1 and B2. The hopping between A1 - B2 leads to a\nconcurrent velocity v3in addition to the Fermi velocity vF. Our noteworthy\noutcome is that the above-mentioned topological change, referred to as the\nLifshitz transition [I. M. Lishitz, Zh. Exp. Teor. Fiz., 38, 1565 (1960) (Sov.\nPhys. JETP 11, 1130 (1960));Y. Lemonik, I.L. Aleiner, C. Toke, and V.I. Fal'ko;\narXiv:1006.1399], is entirely bias-tunable. Furthermore, the many-body effects,\nwhich is known to yield logarithmic renormalizations [C. Hwang, D. A. Siegel,\nSung-Kwan Mo, W. Regan, A. Ismach, Y. Zhang, A. Zettl and A. Lanzara,\narXiv:1208.0567] in the band dispersions of monolayer graphene, is found to\nhave significant effect on the bias-tunability of this transition. We also\nconsider the system where the A atoms of the two layers are over each other and\nthe B atoms of the layers are displaced with respect to each other. The\ntrigonal warping is found to be absent in this case. Instead, the Fermi energy\ndensity of states for zero bias corresponds to the inverted sombrero-like\nstructure. The structure is found to get deformed due to the increase in the\nbias.",
        "positive": "Two-dimensional imaging of the spin-orbit effective magnetic field: We report on spatially resolved measurements of the spin-orbit effective\nmagnetic field in a GaAs/InGaAs quantum-well. Biased gate electrodes lead to an\nelectric-field distribution in which the quantum-well electrons move according\nto the local orientation and magnitude of the electric field. This motion\ninduces Rashba and Dresselhaus effective magnetic fields. The projection of the\nsum of these fields onto an external magnetic field is monitored locally by\nmeasuring the electron spin-precession frequency using time-resolved Faraday\nrotation. A comparison with simulations shows good agreement with the\nexperimental data."
    },
    {
        "anchor": "Surface and bulk Landau levels in thin films of Weyl semimetals: We show that the thin films of Weyl semimetals have a regime of parameters in\nwhich they develop very flat Landau bands under strong magnetic fields.\nAddressing the case of thin films in a perpendicular magnetic field, we observe\nthat two different types of Landau states may arise depending on whether the\nline connecting a pair of opposite Weyl nodes is parallel or perpendicular to\nthe direction of the magnetic field. In the latter instance, we show that the\nflat Landau bands are made of states peaked at the two faces of the thin film.\nWhen the line connecting the Weyl nodes is parallel to the magnetic field, we\nsee instead that the states in the Landau bands take the form of stationary\nwaves with significant amplitude across the bulk of the material. In either\ncase, the states in the flat levels are confined along longitudinal sections of\nthe thin film, turning into edge states with distinctive profiles at the\nlateral boundaries for the two different types of Hall effect.",
        "positive": "The Effect of Electrostatic Screening on a Nanometer Scale Electrometer: We investigate the effect of electrostatic screening on a nanoscale silicon\nMOSFET electrometer. We find that screening by the lightly doped p-type\nsubstrate, on which the MOSFET is fabricated, significantly affects the\nsensitivity of the device. We are able to tune the rate and magnitude of the\nscreening effect by varying the temperature and the voltages applied to the\ndevice, respectively. We show that despite this screening effect, the\nelectrometer is still very sensitive to its electrostatic environment, even at\nroom temperature."
    },
    {
        "anchor": "Image of dynamic local exchange interactions in the dc magnetoresistance\n  of spin-polarized current through a dopant: We predict strong, dynamical effects in the dc magnetoresistance of current\nflowing from a spin-polarized electrical contact through a magnetic dopant in a\nnonmagnetic host. Using the stochastic Liouville formalism we calculate\nclearly-defined resonances in the dc magnetoresistance when the applied\nmagnetic field matches the exchange interaction with a nearby spin. At these\nresonances spin precession in the applied magnetic field is canceled by spin\nevolution in the exchange field, preserving a dynamic bottleneck for spin\ntransport through the dopant. Similar features emerge when the dopant spin is\ncoupled to nearby nuclei through the hyperfine interaction. These features\nprovide a precise means of measuring exchange or hyperfine couplings between\nlocalized spins near a surface using spin-polarized scanning tunneling\nmicroscopy, without any ac electric or magnetic fields, even when the exchange\nor hyperfine energy is orders of magnitude smaller than the thermal energy.",
        "positive": "Proximity-induced spin-polarized magnetocaloric effect in transition\n  metal dichalcogenides: We explore proximity-induced magnetocaloric effect (MCE) on transition metal\ndichalcogenides, focusing on a two-dimensional (2D) MoTe$_2$ monolayer\ndeposited on a ferromagnetic semiconductor EuO substrate connected to a heat\nsource. We model this heterostructure using a tight-binding model,\nincorporating exchange and Rashba fields induced by proximity to EuO, and\nincluding temperature through Fermi statistics. The MCE is induced on the 2D\nMoTe$_2$ layer due to the EuO substrate, revealing large spin-polarized entropy\nchanges for energies out of the band gap of the MoTe$_2$-EuO system. By gating\nthe chemical potential, the MCE can be tuned to produce heating for spin up and\ncooling for spin down across the $K$ and $K'$ valley splitting in the valence\nband, whereas either heats or cools for both spins in the conduction band. The\nRashba field enhances the MCE in the valence zone while decreasing it in the\nconduction bands. The exchange field-induced MCE could be useful to produce\ntunable spin-polarized thermal responses in magnetic proximitized 2D materials."
    },
    {
        "anchor": "Contribution of top barrier materials to high mobility in near-surface\n  InAs quantum wells grown on GaSb(001): Near-surface InAs two-dimensional electron gas (2DEG) systems have great\npotential for realizing networks of multiple Majorana zero modes towards a\nscalable topological quantum computer. Improving mobility in the near-surface\n2DEGs is beneficial for stable topological superconducting states as well as\nfor correlation of multiple Majorana zero modes in a complex network. Here, we\ninvestigate near-surface InAs 2DEGs (13 nm away from the surface) grown on\nGaSb(001) substrates, whose lattice constant is closely matched to InAs, by\nmolecular beam epitaxy. The effect of 10-nm-thick top barrier to the mobility\nis studied by comparing Al$_{0.9}$Ga$_{0.1}$Sb and In$_{0.75}$Ga$_{0.25}$As as\na top barrier on otherwise identical InAs quantum wells grown with identical\nbottom barrier and buffer layers. A 3-nm-thick capping layer on\nAl$_{0.9}$Ga$_{0.1}$Sb top barrier also affects the 2DEG electronic transport\nproperties by modifying scattering from 2D remote ionized impurities at the\nsurface. The highest transport mobility of 650,000 cm$^2$/Vs with an electron\ndensity of 3.81 $\\times$ 10$^{11}$ cm$^{-2}$ was observed in an InAs 2DEG with\nan Al$_{0.9}$Ga$_{0.1}$Sb top barrier and an In$_{0.75}$Ga$_{0.25}$As capping\nlayer. Analysis of Shubnikov-de Haas oscillations in the high mobility sample\nsuggests that long-range scattering, such as remote ionized impurity\nscattering, is the dominant scattering mechanism in the InAs 2DEGs grown on\nGaSb(001) substrates. In comparison to InAs quantum wells grown on\nlattice-mismatched InP, the ones grown on GaSb show smoother surface morphology\nand higher quantum mobility. However, In$_{0.75}$Ga$_{0.25}$As top barrier in\nInAs quantum well grown on GaSb limits the transport mobility by charged\ndislocations formed in it, in addition to the major contribution to scattering\nfrom the alloy scattering.",
        "positive": "Quantum spin/valley Hall effect and topological insulator phase\n  transitions in silicene: We present a theoretical realization of quantum spin and quantum valley Hall\neffects in silicene. We show that combination of an electric field and\nintrinsic spin-orbit interaction leads to quantum phase transitions at the\ncharge neutrality point. This phase transition from a two dimensional\ntopological insulator to a trivial insulating state is accompanied by a\nquenching of the quantum spin Hall effect and the onset of a quantum valley\nHall effect, providing a tool to experimentally tune the topological state of\nsilicene. In contrast to graphene and other conventional topological\ninsulators, the proposed effects in silicene are accessible to experiments."
    },
    {
        "anchor": "High temperature, gate-free quantum anomalous Hall effect with an active\n  capping layer: Quantum anomalous Hall effect (QAHE) was discovered a decade ago, but is\nstill not utilized beyond a handful of research groups, due to numerous\nlimitations such as extremely low temperature, electric field-effect gating\nrequirement, small sample sizes and environmental aging effect. Here, we\npresent a robust platform that provides effective solutions to these problems.\nSpecifically, on this platform, we observe QAH signatures at record high\ntemperatures, with the Hall conductance of 1.00 e2/h at 2.0 K, 0.98 e2/h at 4.2\nK, and 0.92 e2/h at 10 K, on centimeter-scale substrates, without\nelectric-field-effect gating. The key ingredient is an active CrOx capping\nlayer, which substantially boosts the ferromagnetism while suppressing\nenvironmental degradation. With this development, QAHE will now be accessible\nto much broader applications than before.",
        "positive": "Zero modes of the generalized fermion-vortex system in magnetic field: We show that Dirac fermions moving in two spatial dimensions with a\ngeneralized dispersion $E\\sim p^N$, subject to an external magnetic field and\ncoupled to a complex scalar field carrying a vortex defect with winding number\n$Q$ acquire $NQ$ zero modes. This is the same as in the absence of the magnetic\nfield. Our proof is based on selection rules in the Landau level basis that\ndictate the existence and the number of the zero modes. We show that the result\nis insensitive to the choice of geometry and is naturally extended to general\nfield profiles, where we also derive a generalization of the Aharonov-Casher\ntheorem. Experimental consequences of our results are briefly discussed."
    },
    {
        "anchor": "Interactions between directly and parametrically driven vibration modes\n  in a micromechanical resonator: The interactions between parametrically and directly driven vibration modes\nof a clamped-clamped beam resonator are studied. An integrated piezoelectric\ntransducer is used for direct and parametric excitation. First, the parametric\namplification and oscillation of a single mode are analyzed by the power and\nphase dependence below and above the threshold for parametric oscillation.\nThen, the motion of a parametrically driven mode is detected by the induced\nchange in resonance frequency in another mode of the same resonator. The\nresonance frequency shift is the result of the nonlinear coupling between the\nmodes by the displacement-induced tension in the beam. These nonlinear modal\ninteractions result in the quadratic relation between the resonance frequency\nof one mode and the amplitude of another mode. The amplitude of a\nparametrically oscillating mode depends on the square root of the pump\nfrequency. Combining these dependencies yields a linear relation between the\nresonance frequency of the directly driven mode and the frequency of the\nparametrically oscillating mode.",
        "positive": "Controlled anisotropic dynamics of tightly bound skyrmions in a\n  synthetic ferrimagnet due to skyrmion-deformation mediated by induced\n  uniaxial in-plane anisotropy: We study speed and skew deflection-angle dependence on skyrmion deformations\nof a tightly bound two-skyrmion state in a synthetic ferrimagnet. We condsider\nhere, an in-plane uniaxial magnetocrystalline anisotropy-term in order to\ninduce lateral shape distortions and an overall size modulation of the\nskyrmions due to a reduction of the effective out-of-plane anisotropy, thus\naffecting the skyrmion speed, skew-deflection and inducing anisotropy in these\nquantities with respect to the driving current-angle. Because of frustrated\ndipolar interactions in a synthetic ferrimagnet, sizeable skyrmion deformations\ncan be induced with relatively small induced anisotropy constants and thus a\nwide range of tuneability can be achieved. We also show analytically, that a\nconsequence of the skyrmion deformation can, under certain conditions cause a\nskyrmion deflection with respect to driving-current angles, unrelated to the\ntopological charge. Results are analyzed by a combination of micromagnetic\nsimulations and a compound particle description within the Thiele-formalism\nfrom which an over-all mobility tensor is constructed. This work offers an\nadditional path towards in-situ tuning of skyrmion dynamics."
    },
    {
        "anchor": "Projected Performance Advantage of Multilayer Graphene Nanoribbon as\n  Transistor Channel Material: The performance limits of the multilayer graphene nanoribbon (GNR)\nfield-effect transistor (FET) are assessed and compared to those of monolayer\nGNR FET and carbon nanotube (CNT) FET. The results show that with a thin high-k\ngate insulator and reduced interlayer coupling, multilayer GNR FET can\nsignificantly outperform its CNT counterpart with a similar gate and bandgap in\nterms of the ballistic on-current. In the presence of optical phonon\nscattering, which has a short mean free path in the graphene-derived\nnanostructures, the advantage of the multilayer GNRFET is even more\nsignificant. The simulation results indicate multilayer GNRs with\nincommensurate non-AB stacking and weak interlayer coupling are the best\ncandidate for high performance GNR FETs.",
        "positive": "Three-terminal semiconductor junction thermoelectric devices: improving\n  performance: A three-terminal thermoelectric device based on a $p$-$i$-$n$ semiconductor\njunction is proposed, where the intrinsic region is mounted onto a, typically\nbosonic, thermal terminal. Remarkably, the figure of merit of the device is\ngoverned also by the energy distribution of the {\\em bosons} participating in\nthe transport processes, in addition to the electronic one. An enhanced figure\nof merit can be obtained when the relevant distribution is narrow and the\nelectron-boson coupling is strong (such as for optical phonons). We study the\nconditions for which the figure of merit of the three-terminal junction can be\ngreater than those of the usual thermoelectric devices made of the same\nmaterial. A possible setup with a high figure of merit, based on\nBi$_2$Te$_3$/Si superlattices, is proposed."
    },
    {
        "anchor": "Read-Green points and level crossings in XXZ central spin models and\n  $p_x+ip_y$ topological superconductors: In this work, we study the full set of eigenstates of a $p_x+ip_y$\ntopological superconductor coupled to a particle bath which can be described in\nterms of an integrable Hamiltonian of the Richardson-Gaudin class. The results\nderived in this work also characterise the behaviour of an anisotropic XXZ\ncentral spin model in a external magnetic field since both types of Hamiltonian\nare know to share the exact same conserved quantities making them formally\nequivalent.\n  We show how by ramping the coupling strength (or equivalently the magnetic\nfield acting in the z-direction on the central spin), each individual\neigenstate undergoes a sequence of gain/loss of excitations when crossing the\nspecific values known as Read-Green points. These features are shown to be\ncompletely predictable, for every one of the $2^N$ eigenstates, using only two\nintegers obtainable easily from the zero-coupling configuration which defines\nthe eigenstate in question.\n  These results provide a complete map of the particle-number sectors\n(superconductor) or magnetisation sectors (central spin) involved in the large\nnumber of level-crossings which occur in these systems at the Read-Green\npoints. It further allows us to define quenching protocols which could create\nstates with remarkably large excitation-number fluctuations.",
        "positive": "Sign Reversal of anisotropic magnetoresistance in La0.7Ca0.3MnO3/STO\n  ultrathin films: We present the observation of strain induced sign reversal of anisotropic\nmagnetoresistance (AMR) in LCMO (LCMO) ultrathin films (thickness 4 nm)\ndeposited on STO (001) substrate (STO). We have also observed unusually large\nAMR in LCMO/STO thin films with thickness of 6 nm below but close to its Curie\ntemperature (TC) which decrease as the film thickness increases. The sign\nreversal of AMR (with a maximum value of - 6) with magnetic field or\ntemperature for the 4 nm thin film may be attributed to the increase in tensile\nstrain in the plane of the thin film which in turn facilitates the rotation of\nthe magnetization easy axis."
    },
    {
        "anchor": "Steerable current-driven emission of spin waves in magnetic vortex pairs: The efficient excitation of spin waves is a key challenge in the realization\nof magnonic devices. We demonstrate the current-driven generation of spin waves\nin antiferromagnetically coupled magnetic vortices. We employ time-resolved\nscanning transmission X-ray microscopy (TR-STXM) to directly image the emission\nof spin waves upon the application of an alternating current flowing directly\nthrough the magnetic stack. Micromagnetic simulations allow us to identify the\norigin of the excitation to be the current-driven Oersted field, which in the\npresent system proves to be orders of magnitude more efficient than the\ncommonly used excitation via stripline antennas. Our numerical studies also\nreveal that the spin-transfer torque can lead to the emission of spin waves as\nwell, yet only at much higher current amplitudes. By using magnetostrictive\nmaterials, we futhermore demonstrate that the direction of the magnon\npropagation can be steered by increasing the excitation amplitude, which\nmodifies the underlying magnetization profile through an additional anisotropy\nin the magnetic layers. The demonstrated methods allow for the efficient and\ntunable excitation of spin waves, marking a significant advance in the\ngeneration and control of spin waves in magnonic devices.",
        "positive": "Resonant weak-value enhancement for solid-state quantum metrology: Quantum metrology that employs weak-values can potentially effectuate\nparameter estimation with an ultra-high sensitivity and has been typically\nexplored across quantum optics setups. Recognizing the importance of sensitive\nparameter estimation in the solid-state, we propose a spintronic device\nplatform to realize this. The setup estimates a very weak localized Zeeman\nsplitting by exploiting a resonant tunneling enhanced magnetoresistance\nreadout. We establish that this paradigm offers nearly optimal performance with\na quantum Fisher information enhancement of about $10^4$ times that of single\nhigh-transmissivity barriers. The obtained signal also offers a high\nsensitivity in the presence of dephasing effects typically encountered in the\nsolid state. These results put forth definitive possibilities in harnessing the\ninherent sensitivity of resonant tunneling for solid-state quantum metrology\nwith potential applications, especially, in the sensitive detection of small\ninduced Zeeman effects in quantum material heterostructures."
    },
    {
        "anchor": "Quantum Interference in Single Molecule Electronic Systems: We present a general analytical formula and an ab initio study of quantum\ninterference in multi-branch molecules. Ab initio calculations are used to\ninvestigate quantum interference in a benzene-1,2-dithiolate (BDT) molecule\nsandwiched between gold electrodes and through oligoynes of various lengths. We\nshow that when a point charge is located in the plane of a BDT molecule and its\nposition varied, the electrical conductance exhibits a clear interference\neffect, whereas when the charge approaches a BDT molecule along a line normal\nto the plane of the molecule and passing through the centre of the phenyl ring,\ninterference effects are negligible. In the case of olygoynes, quantum\ninterference leads to the appearance of a critical energy $E_c$, at which the\nelectron transmission coefficient $T(E)$ of chains with even or odd numbers of\natoms is independent of length. To illustrate the underlying physics, we derive\na general analytical formula for electron transport through multi-branch\nstructures and demonstrate the versatility of the formula by comparing it with\nthe above ab-initio simulations. We also employ the analytical formula to\ninvestigate the current inside the molecule and demonstrate that large counter\ncurrents can occur within a ring-like molecule such as BDT, when the point\ncharge is located in the plane of the molecule. The formula can be used to\ndescribe quantum interference and Fano resonances in structures with branches\ncontaining arbitrary elastic scattering regions connected to nodal sites.",
        "positive": "The magnetic response of disordered metallic rings: the large\n  contribution of the far levels: We calculate the orbital linear magnetic response of disordered metallic\nrings to an Aharonov-Bohm flux using the BCS model for attractive\nelectron-electron interaction. The contribution of all levels including those\nup to a high energy cutoff results in a much larger value than previously\nobtained using the local interaction model. The possible relevance of our\nresults to the resolution of the discrepancy between the experimental and\ntheoretical values for the ensemble-averaged persistent currents in these\nsystems is discussed."
    },
    {
        "anchor": "Coulomb-interaction effects in full counting statistics of a quantum-dot\n  Aharonov-Bohm interferometer: We study the effect of Coulomb interaction on the full counting statistics of\nan Aharonov-Bohm (AB) interferometer with a single-level quantum dot in one arm\nin the regime of weak dot-lead and lead-lead tunnel couplings. In the absence\nof Coulomb interaction, the interference processes are of nonresonant nature\nwith an even AB flux dependence and obey bidirectional Poissonian statistics.\nFor large charging energy, the statistic of these processes changes. In\naddition, processes of resonant nature with an odd flux dependence appear. In\nthe limit of strongly asymmetric tunnel couplings from the dot to the left and\nright leads, their statistics is found to be strongly super-Poissonian.",
        "positive": "Dirac Electrons in a Dodecagonal Graphene Quasicrystal: Quantum states of quasiparticles in solids are dictated by symmetry. Thus, a\ndiscovery of unconventional symmetry can provide a new opportunity to reach a\nnovel quantum state. Recently, Dirac and Weyl electrons have been observed in\ncrystals with discrete translational symmetry. Here we experimentally\ndemonstrate Dirac electrons in a two-dimensional quasicrystal without\ntranslational symmetry. A dodecagonal quasicrystal was realized by epitaxial\ngrowth of twisted bilayer graphene rotated exactly 30 degree. The graphene\nquasicrystal was grown up to a millimeter scale on SiC(0001) surface while\nmaintaining the single rotation angle over an entire sample and was\nsuccessfully isolated from a substrate, demonstrating its structural and\nchemical stability under ambient conditions. Multiple Dirac cone replicated\nwith the 12-fold rotational symmetry were observed in angle resolved\nphotoemission spectra, showing its unique electronic structures with anomalous\nstrong interlayer coupling with quasi-periodicity. Our study provides a new way\nto explore physical properties of relativistic fermions with controllable\nquasicrystalline orders."
    },
    {
        "anchor": "Nonlinear parametric amplification in a tri-port nanoelectromechanical\n  device: We report on measurements performed at low temperatures on a\nnanoelectromechanical system (NEMS) under (capacitive) parametric pumping. The\nexcitations and detection schemes are purely electrical, and enable in the\npresent experiment the straightforward measurement of forces down to about a\nfemtonewton, for displacements of an Angstr\\\"om, using standard room\ntemperature electronics. We demonstrate that a small (linear) force applied on\nthe device can be amplified up to more than a 100 times, while the system is\n{\\it truly moving}. We explore the dynamics up to about 50$~$nm deflections for\ncantilevers about 200$~$nm thick by 3$~$$\\mu$m long oscillating at a frequency\nof 7$~$MHz. We present a generic modeling of nonlinear parametric\namplification, and give analytic theoretical solutions enabling the fit of\nexperimental results. We finally discuss the practical limits of the technique,\nwith a particular application: the measurement of {\\it anelastic damping} in\nthe metallic coating of the device with an exceptional resolution of about\n0.5$~$\\%.",
        "positive": "Ab initio mobility of mono-layer MoS2 and WS2: comparison to experiments\n  and impact on the device characteristics: We combine the linearized Boltzmann Transport Equation (LBTE) and quantum\ntransport by means of the Non-equilibrium Green's Functions (NEGF) to simulate\nsingle-layer MoS2 and WS2 ultra-scaled transistors with carrier mobilities\nextracted from experiments. Electron-phonon, charged impurity, and surface\noptical phonon scattering are taken into account with all necessary parameters\nderived from ab initio calculations or measurements, except for the impurity\nconcentration. The LBTE method is used to scale the scattering self-energies of\nNEGF, which only include local interactions. This ensures an accurate\nreproduction of the measured mobilities by NEGF. We then perform device\nsimulations and demonstrate that the considered transistors operate far from\ntheir performance limit (from 50% for MoS2 to 60% for WS2). Higher quality\nmaterials and substrate engineering will be needed to improve the situation."
    },
    {
        "anchor": "Theoretical study on the slit experiments in the Rashba electron systems: We develop a theory of designing slit experiments in two-dimensional electron\nsystems with the Rashba spin-orbit interaction. By simulating the\nspatiotemporal dynamics of electrons passing through a single slit or a double\nslit, we find that the interference fringes of the electron probability density\nattain specific spin orientations via the precession of spins around effective\nmagnetic fields mediated by the Rashba spin-orbit interaction whose directions\nare determined by the propagation path. The spin orientations of the fringes\ncan be controlled by tuning the Rashba spin-orbit parameter, which can be\nachieved by applying an electric gate voltage. This phenomenon can be exploited\nto implement electrically tunable transmission of spin information and to\ngenerate spin-polarized currents.",
        "positive": "Rosen-Zener interferometry with Ultracold Atoms: We propose a time-domain \"interferometer\" based on ultracold Bose atoms\nloaded on a double well potential. By the adiabatic Rosen-Zener process, the\nbarrier between two wells is ramped down slowly, held for a while, then ramped\nback. Starting with a coherent state of double well system, the final\noccupations on one well show interesting interference fringes in the\ntime-domain. The fringe pattern is sensitive to the initial state, the\ninteratomic interaction, and the external forces such as gravity which can\nchange the shape of the double well. In this sense, this interferometric scheme\nhas the potentials for precision measurements with ultracold atoms. The\nunderlying mechanism is revealed and possible applications are discussed."
    },
    {
        "anchor": "Research progress of electronic properties of self-assembled\n  semiconductor quantum dots: Self-assembled semiconductor quantum dot is a new type of artificially\ndesigned and grown function material which exhibits quantum size effect,\nquantum interference effect, surface effect, quantum tunneling-Coulumb-blockade\neffect and nonlinear optical effect. Due to advantages like less crystal\ndefects and relatively simpler fabrication technology, that material may be of\nimportant value in future nanoelectronic device researches. In the order of\nvertical transport, lateral transport and charge storage, this paper gives a\nbrief introduction of recent advances in the electronic properties of that\nmaterial and an analysis of problems and perspectives.",
        "positive": "New exact results for the two-phase model with several conserved\n  currents: We consider the macroscopic transport properties of two-dimensional random\nbinary mixtures with identical spatial distributions of the two phases.\nPrevious studies have obtained exact analytical results for the electrical\nconductivity of a single layer with and without a magnetic field, as well as\nfor the thermoelectric response of a magnetic field-free double-layer. Here, we\ngeneralize these exact solutions to the magneto-thermoelectric response of a\nsingle layer and to the thermoelectric response of a double-layer. The\nmagneto-thermoelectric transport coefficients of the double-layer are\ncalculated perturbatively for weak magnetic field."
    },
    {
        "anchor": "Tunnel spin injection into graphene using Al2O3 barrier grown by atomic\n  layer deposition on functionalized graphene surface: We demonstrate electrical tunnel spin injection from a ferromagnet to\ngraphene through a high-quality Al2O3 grown by atomic layer deposition (ALD).\nThe graphene surface is functionalized with a self-assembled monolayer of\n3,4,9,10-perylene tetracarboxylic acid (PTCA) to promote adhesion and growth of\nAl2O3 with a smooth surface. Using this composite tunnel barrier of ALD-Al2O3\nand PTCA, a spin injection signal of 30 ohm has been observed from non-local\nmagnetoresistance measurements at 45 K, revealing potentially high performance\nof ALD-Al2O3/PTCA tunnel barrier for spin injection into graphene.",
        "positive": "Separating parallel conduction from two-dimensional magnetotransport in\n  high mobility InP/InGaAs MOCVD-grown heterostructures: In this Letter, four-point magnetotransport of high mobility InGaAs/InP\nheterointerfaces is measured from 1.6 K to 300 K and from 0 to 15 T, and an\nanalysis is shown whereby the mobility and density of the two-dimensional (2D)\naccumulation layer can be separately characterized from that of the parallel\nconducting dopant layer over all but a small intermediate temperature range.\nStandard magnetotransport regimes are defined as the temperature increases from\n1.6 K to 300 K, namely quantum Hall (QH), Shubnikov de Haas (SdH), and Drude\nregimes (D), and in the QH and D regimes different analyses are applied to\ndeduce densities and mobilities of both layers separately. Quantitative\nconditions for the intermediate SdH regime are defined, within which both QH\nand D analyses fail. The density and activation energy of unintentional donors\nat the InP epilayer/substrate interface is deduced. At base temperature, QH\nminima are resolved down to B = 0.4 T at nu = 20, revealing a mobility of mu =\n160,000 cm^2/Vs. The 2D system maintains this high mobility up to at least 40 K\nin this high quality structure."
    },
    {
        "anchor": "Enhancement of the thermoelectric figure of merit in a quantum dot due\n  to the Coulomb blockade effect: We investigate the figure of merit of a quantum dot (QD) in the Coulomb\nblockade regime. It is found that the figure of merit $ZT$ may be quite high if\nonly single energy level in the QD is considered. On the other hand, with two\nor multi energy levels in the QD and without the Coulomb interaction, the $ZT$\nis strongly suppressed by the bipolar effect due to small level spacing.\nHowever, in the presence of the Coulomb interaction, the effective level\nspacing is enlarged and the bipolar effect is weakened, resulting in $ZT$ to be\nconsiderably high. Thus, it is more likely to find a high efficient\nthermoelectric QDs with large Coulomb interaction. By using the parameters for\na typical QD, the $ZT$ can reach over 5.",
        "positive": "Double resonance Raman study of disorder in CVD-grown single-walled\n  carbon nanotubes: Single-walled carbon nanotubes (SWNTs) with varying degrees of disorder were\ninvestigated using multiple-excitation Raman spectroscopy. The lattice disorder\nwas imparted into the nanotubes by the addition of varying amounts of sulfur to\nthe iron catalyst in a thermal chemical vapor deposition process. Changes in\nthe intensities of peaks occurring due to a double resonance Raman process were\nstudied. The intensity of the disorder-induced D band increased with a decrease\nin the sulfur content. Upon post-synthesis heat treatment, the double resonance\nprocess got quenched due to defect healing. The second order G' band and iTOLA\nbands exhibited a two-peak structure, of which one of the peaks is relatively\nmore sensitive to defects and decreased in intensity with heat treatment."
    },
    {
        "anchor": "Finite-Volume Self-Consistent approach for electronic properties at\n  ultra-low temperatures: Theory and application to 1D electron gas at the\n  Si-SiO2 interface: Achieving self-consistent convergence for conventional effective-mass\napproaches at ultralow temperatures (below 4.2 K) is a challenging task, which\nmostly lies in the discontinuities in material properties (e.g.,\neffective-mass, electron affinity, dielectric constant). In this article, we\ndevelop a novel self consistent approach based on cell centered Finite Volume\ndiscretization of the Sturm-Liouville form of the effective mass Schrodinger\nequation and generalized Poisson's equation (FV-SP). We apply this approach to\nsimulate the one dimensional electron gas (1DEG) formed at the Si-SiO2\ninterface via a top gate. We find excellent self-consistent convergence from\nhigh to extreme low (as low as 50 mK) temperatures. We further examine the\nsolidity of FV-SP method by changing external variables such as the\nelectrochemical potential and the accumulative top gate voltage. Our approach\nallows for counting electron-electron interactions. Our results demonstrate\nthat FV-SP approach is a powerful tool to solve effective mass Hamiltonians.",
        "positive": "Magnetic-field switchable metal-insulator transitions in a quasi-helical\n  conductor: We study Anderson localization in disordered helical conductors that are\nobtained from one-dimensional conductors with spin-orbit interaction and a\nmagnetic field, or from equivalent systems. We call such conductors\n\"quasi-helical\" because the spins of the counterpropagating modes are not\nperfectly antiparallel and have a small spin-wavefunction overlap that is\ntunable by the magnetic field. Due to the overlap, disorder backscattering is\npossible and allows a localization transition. A conductor can pass through two\nlocalization transitions with increasing field, one from the conventionally\nlocalized system to the quasi-helical conductor (with localization length\nexceeding the system length), and one at a higher field again to a localized\nstate, due now, however, to backscattering below the magnetic field induced\npseudo-gap. We investigate these transitions using a unified two-step\nrenormalization group approach."
    },
    {
        "anchor": "Optically controllable magnetism in atomically thin semiconductors: Electronic states in two-dimensional layered materials can exhibit a\nremarkable variety of correlated phases including Wigner-crystals, Mott\ninsulators, charge density waves, and superconductivity. Recent experimental\nand theoretical research has indicated that ferromagnetic phases can exist in\nelectronically-doped transition metal dichalcogenide (TMD) semiconductors, but\na stable magnetic state at zero magnetic field has eluded detection. Here, we\nexperimentally demonstrate that mesoscopic ferromagnetic order can be generated\nand controlled by local optical pumping in monolayer WSe2 at zero applied\nmagnetic field. In a spatially resolved pump-probe experiment, we use\npolarization-resolved reflectivity from excitonic states as a probe of\ncharge-carrier spin polarization. When the sample is electron-doped at density\n$n_e = 10^{12} cm^{-2}$, we observe that a local, circularly-polarized,\nmicrowatt-power optical pump breaks the symmetry between equivalent\nferromagnetic spin configurations and creates magnetic order which extends over\nmesoscopic regions as large as 8 um x 5 um, bounded by sample edges and folds\nin the 2D semiconductor. The experimental signature of magnetic order is\ncircular dichroism (CD) in reflectivity from the excitonic states, with\nmagnitude exceeding 20% at resonant wavelengths. The helicity of the pump\ndetermines the orientation of the magnetic state, which can be aligned along\nthe two principle out-of-plane axes. In contrast to previous studies in 2D\nmaterials that have required non-local, slowly varying magnetic fields to\nmanipulate magnetic phases, the demonstrated capability to control long-range\nmagnetism and corresponding strong CD with local and tunable optical pumps is\nhighly versatile. This discovery will unlock new TMD-based spin and optical\ntechnologies and enable sophisticated control of correlated electron phases in\ntwo-dimensional electron gases (2DEGs).",
        "positive": "Anomalous Hall effect of light-driven three-dimensional Dirac electrons\n  in bismuth: Recent advancement in laser technology has opened the path toward the\nmanipulation of functionalities in quantum materials by intense coherent light.\nHere, we study three-dimensional (3D) Dirac electrons driven by circularly\npolarized light (CPL), when the photon energy lies within the Dirac bands. As\nan experimental realization of this setup, we irradiate a thin film sample of\nelemental bismuth, which is a well-known semimetal hosting 3D Dirac electrons,\nwith mid-infrared CPL. We successfully observe the emergence of the anomalous\nHall effect (AHE) via terahertz Faraday rotation that is both\npump-helicity-dependent and instantaneous. We compare our experimental findings\nwith the results of Floquet theory, which is a powerful framework for analyzing\nthe electronic band structure driven by coherent light. The contribution from\nthe band structures near the one-photon resonant positions to the AHE shows a\nfield-strength dependence consistent with our experimental results. The\neffective Hamiltonian on which we base our model calculations also implies that\na pair of \"double Weyl points\" emerge due to the CPL-induced hybridization\nbetween the occupied and unoccupied 3D Dirac bands. Our findings shed light on\nultrafast control of material properties in nonlinear topological optics."
    },
    {
        "anchor": "Chirality in Quantum Computation with Spin Cluster Qubits: We study corrections to the Heisenberg interaction between several lateral,\nsingle-electron quantum dots. We show, using exact diagonalization, that\nthree-body chiral terms couple triangular configurations to external sources of\nflux rather strongly. The chiral corrections impact single qubit encodings\nutilizing loops of three or more Heisenberg coupled quantum dots.",
        "positive": "Universal Linear Density of States for Tunneling into the\n  Two-Dimensional Electron Gas in a Magnetic field: A new technique permits high fidelity measurement of the tunneling density of\nstates (TDOS) of the two-dimensional electron gas. The obtained TDOS contains\nno distortions arising from low 2D in-plane conductivity and includes the\ncontribution from localized tunneling sites. In a perpendicular magnetic field,\na pseudogap develops in the TDOS at the Fermi level. Improved sensitivity\nenables resolution of a linear dependence of the TDOS on energy near the Fermi\nenergy. The slopes of this linear gap are strongly field dependent. The data\nare suggestive of a new model of the gap at low energies."
    },
    {
        "anchor": "Quantum Hall effect in graphene with superconducting electrodes: We have realized an integer quantum Hall system with superconducting contacts\nby connecting graphene to niobium electrodes. Below their upper critical field\nof 4 tesla, an integer quantum Hall effect coexists with superconductivity in\nthe leads, but with a plateau conductance that is larger than in the normal\nstate. We ascribe this enhanced quantum Hall plateau conductance to Andreev\nprocesses at the graphene-superconductor interface leading to the formation of\nso-called Andreev edge-states. The enhancement depends strongly on the\nfilling-factor, and is less pronounced on the first plateau, due to the special\nnature of the zero energy Landau level in monolayer graphene.",
        "positive": "Plasmon-exciton polaritons in 2D semiconductor/metal interfaces: The realization and control of polaritons is of paramount importance in the\nprospect of novel photonic devices. Here, we investigate the emergence of\nplasmon-exciton polaritons in hybrid structures consisting of a two-dimensional\n(2D) transition metal dichalcogenide (TMDC) deposited onto a metal substrate or\ncoating a metallic thin-film. We determine the polaritonic spectrum and show\nthat, in the former case, the addition of a top dielectric layer, and, in the\nlatter, the thickness of the metal film,can be used to tune and promote\nplasmon-exciton interactions well within the strong coupling regime. Our\nresults demonstrate that Rabi splittings exceeding 100 meV can be readily\nachieved in planar dielectric/TMDC/metal structures under ambient conditions.\nWe thus believe that this work provides a simple and intuitive picture to\ntailor strong coupling in plexcitonics, with potential applications for\nengineering compact photonic devices with tunable optical properties."
    },
    {
        "anchor": "Inducing Kondo Screening of Vacancy Magnetic Moments in Graphene with\n  Gating and Local Curvature: In normal metals, the magnetic-moment of impurity-spins disappears below a\ncharacteristic Kondo temperature, TK. This marks the formation of a polarized\ncloud of conduction band electrons that screen the magnetic moment . In\ncontrast, moments embedded in insulators remain unscreened at all temperatures.\nThis raises the question about the fate of magnetic-moments in intermediate,\npseudogap systems, such as graphene. In these systems coupling between the\nlocal moment and the conduction band electrons is predicted to drive a quantum\nphase-transition between a local-moment phase and a Kondo-screened singlet\nphase as illustrated in Fig. 1A. However, attempts to experimentally confirm\nthese predictions and their intriguing consequences such as the ability to\nelectrostatically tune magnetic-moments, have been elusive. Here we report the\nobservation of Kondo screening and the quantum phase-transition between\nscreened and unscreened phases of vacancy magnetic-moments in graphene. Using\nscanning-tunneling-microscopy (STM), spectroscopy (STS) and\nnumerical-renormalization-group (NRG) calculations, we identified\nKondo-screening by its spectroscopic signature and mapped the quantum\nphase-transition as a function of coupling strength and chemical potential. We\nshow that the coupling strength can be tuned across this transition by\nvariations in the local curvature and furthermore that the transition makes it\npossible to turn the magnetic-moment on and off with a gate voltage.",
        "positive": "Quantum dot spectroscopy using cavity QED: Cavity quantum electrodynamics has attracted substantial interest, both due\nto its potential role in the field of quantum information processing and as a\ntestbed for basic experiments in quantum mechanics. Here, we show how cavity\nquantum electrodynamics using a tunable photonic crystal nanocavity in the\nstrong coupling regime can be used for single quantum dot spectroscopy. From\nthe distinctive avoided crossings observed in the strongly coupled system we\ncan identify the neutral and single positively charged exciton as well as the\nbiexciton transitions. Moreover we are able to investigate the fine structure\nof those transitions and to identify a novel cavity mediated mixing of bright\nand dark exciton states, where the hyperfine interactions with lattice nuclei\npresumably play a key role. These results are enabled by a deterministic\ncoupling scheme which allowed us to achieve unprecedented coupling strengths in\nexcess of 0.15 meV."
    },
    {
        "anchor": "Observation of Electronic Raman Scattering in Metallic Carbon Nanotubes: We present experimental measurements of the electronic contribution to the\nRaman spectra of individual metallic single-walled carbon nanotubes (MSWNTs).\nPhotoexcited carriers are inelastically scattered by a continuum of low-energy\nelectron-hole pairs created across the graphenelike linear electronic subbands\nof the MSWNTs. The optical resonances in MSWNTs give rise to well-defined\nelectronic Raman peaks. This resonant electronic Raman scattering is a unique\nfeature of the electronic structure of these one-dimensional quasimetals.",
        "positive": "Helical Quantum States in HgTe Quantum Dots with Inverted Band\n  Structures: We investigate theoretically the electron states in HgTe quantum dots (QDs)\nwith inverted band structures. In sharp contrast to conventional semiconductor\nquantum dots, the quantum states in the gap of HgTe quantum dot with an\ninverted band structure are fully spin-polarized, and show ring-like density\ndistributions near the boundary of the QD and spin-angular momentum locking.\nThe persistent charge currents and magnetic moments, i.e., the Aharonov-Bohm\neffect, can be observed in such QD structure and oscillate with increasing\nmagnetic fields. This feature offers us a practical way to detect these exotic\nring-like edge states using the SQUID technique."
    },
    {
        "anchor": "RKKY interaction of magnetic impurities in Dirac and Weyl semimetals: We theoretically study the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction\nbetween magnetic impurities in both Dirac and Weyl semimetals (SMs). We find\nthat the internode process, as well as the unique three-dimensional\nspin-momentum locking, has significant influences on the RKKY interaction,\nresulting in both a Heisenberg and an Ising term, and an additional\nDzyaloshinsky-Moriya term if the inversion symmetry is absent. These\ninteractions can lead to rich spin textures and possible ferromagnetism in\nDirac and time-reversal symmetry-invariant Weyl SMs. The effect of anisotropic\nDirac and Weyl nodes on the RKKY interaction is also discussed. Our results\nprovide an alternative scheme to engineer topological SMs and shed new light on\nthe application of Dirac and Weyl SMs in spintronics.",
        "positive": "Spatial dispersion of magnetic-edge magnetoplasmons: Effect of\n  semi-infinite gate: Magnetic-edge magnetoplasmons (MEMPs) are obtained for a two-dimensional\nelectron system (2DES) with atop semi-infinite metallic gate, at a distance\n$d$, and atop semi-infinite ferromagnetic film at a strong perpendicular\nmagnetic field. For two most fast MEMPs, one with positive chirality and other\nwith negative chirality, a strong spatial dispersion, due to effect of metallic\nhalf-plane gate, is obtained; some slower MEMPs manifest spatial dispersion\ntoo. Present MEMPs are localized at the magnetic-edge that is close to the\nwedge of metallic half-plane gate; the metallic wedge enhances localization of\nMEMPs at magnetic-edge. Obtained spatial dispersion has unconventional form. In\nparticular, for two most fast MEMPs the phase velocities, $\\omega/k_{x}$, are\nthe linear polynomials on the wave vector $k_{x}$ in the long-wavelength\nregion, $k_{x}d \\ll 1$. Strong effect of the ferromagnetic film hysteresis on\nthe MEMPs phase velocities and their anti-crossings are obtained for $0<k_{x}d\n\\leq1$. Two MEMPs of opposite chirality, especially two most fast MEMPs, at\nsome resonance frequency can create a resonance circuit, with closed wave path\nalong a fraction of the magnetic edge perimeter, with a total change of the\nwave phase given by an integer of $2\\pi$."
    },
    {
        "anchor": "Controllable frequency tunability and parabolic-like threshold current\n  behavior in spin Hall nano-oscillators: We investigate the individual impacts of critical magnetodynamical\nparameters-effective magnetization and magnetic damping-on the auto-oscillation\ncharacteristics of nano-constriction-based Spin Hall Nano-Oscillators (SHNOs).\nOur micromagnetic simulations unveil a distinctive non-monotonic relationship\nbetween current and auto-oscillation frequency in out-of-plane magnetic fields.\nThe influence of effective magnetization on frequency tunability varies with\nout-of-plane field strengths. At large out-of-plane fields, the frequency\ntunability is predominantly governed by effective magnetization, achieving a\ncurrent tunability of 1 GHz/mA-four times larger than that observed at the\nlowest effective magnetization. Conversely, at low out-of-plane fields,\nalthough a remarkably high-frequency tunability of 4 GHz/mA is observed, the\neffective magnetization alters the onset of the transition from a linear-like\nmode to a spin-wave bullet mode. Magnetic damping primarily affects the\nthreshold current with negligible impact on auto-oscillation frequency\ntunability. The threshold current scales linearly with increased magnetic\ndamping at a constant out-of-plane field but exhibits a parabolic behavior with\nvariations in out-of-plane fields. This behavior is attributed to the\nqualitatively distinct evolution of the auto-oscillation mode across different\nout-of-plane field values. Our study not only extends the versatility of SHNOs\nfor oscillator-based neuromorphic computing with controllable frequency\ntunability but also unveils the intricate auto-oscillation dynamics in\nout-of-plane fields.",
        "positive": "Exciton effective mass enhancement in coupled quantum wells in electric\n  and magnetic fields: We present a calculation of exciton states in semiconductor coupled quantum\nwells (CQWs) in the presence of electric and magnetic fields applied\nperpendicular to the QW plane. The exciton Schr\\\"odinger equation is solved in\nreal space in three dimensions to obtain the Landau levels of both direct and\nindirect excitons. Calculation of the exciton energy levels and oscillator\nstrengths enables mapping of the electric and magnetic field dependence of the\nexciton absorption spectrum. For the ground state of the system, we evaluate\nthe Bohr radius, optical lifetime, binding energy and dipole moment. The\nexciton mass renormalization due to the magnetic field is calculated using a\nperturbative approach. We predict a non-monotonous dependence of the exciton\nground state effective mass on magnetic field. Such a trend is explained in a\nclassical picture, in terms of the ground state tending from an indirect to a\ndirect exciton with increasing magnetic field."
    },
    {
        "anchor": "Asymmetric power dissipation in electronic transport through a quantum\n  point contact: We investigate the power dissipated by an electronic current flowing through\na quantum point contact in a two-dimensional electron gas. Based on the\nLandauer-B\\\"uttiker approach to quantum transport, we evaluate the power that\nis dissipated on the two sides of the constriction as a function of the Fermi\nenergy, temperature, and applied voltage. We demonstrate that an asymmetry\nappears in the dissipation, which is most pronounced when the quantum point\ncontact is tuned to a conductance step where the transmission strongly depends\non energy. At low temperatures, the asymmetry is enhanced when the temperature\nincreases. An estimation for the position of the maximum dissipation is\nprovided.",
        "positive": "Anomalous longitudinal relaxation of nuclear spins in CaF$_2$: We consider the effect of non-secular resonances for interacting nuclear\nspins in solids which were predicted theoretically to exist in the presence of\nstrong static and strong radio-frequency magnetic fields. These resonances\nimply corrections to the standard secular approximation for the nuclear\nspin-spin interaction in solids, which, in turn, should lead to an anomalous\nlongitudinal relaxation in nuclear magnetic resonance experiments. In this\narticle, we investigate the feasibility of the experimental observation of this\nanomalous longitudinal relaxation in calcium fluoride (CaF$_2$) and conclude\nthat such an observation is realistic."
    },
    {
        "anchor": "Fabrication of Nano-Scale Gaps in Integrated Circuits: Nano-size objects like metal clusters present an ideal system for the study\nof quantum phenomena and for constructing practical quantum devices.\nIntegrating these small objects in a macroscopic circuit is, however, a\ndifficult task. So far the nanoparticles have been contacted and addressed by\nhighly sophisticated techniques which are not suitable for large scale\nintegration in macroscopic circuits. We present an optical lithography method\nthat allows for the fabrication of a network of electrodes which are separated\nby gaps of controlled nanometer size. The main idea is to control the gap size\nwith subnanometer precision using a structure grown by molecular beam epitaxy.",
        "positive": "Near-infrared photothermal response of plasmonic gold-coated\n  nanoparticles in tissues: We propose a new approach to understand the time-dependent temperature\nincreasing process of gold-silica core-shell nanoparticles injected into\nchicken tissues under near-infrared laser irradiation. Gold nanoshells strongly\nabsorb near-infrared radiations and efficiently transform absorbed energy into\nheat. Temperature rise given by experiments and numerical calculations based on\nbioheat transfer are in good agreement. Our work improves the analysis of a\nrecent study [Richardson et al., Nano Lett. 9, 1139 (2009)] by including\neffects of the medium perfusion on temperature increase. The theoretical\nanalysis can also be used to estimate the distribution of nanoparticles in\nexperimental samples and provide a relative accuracy prediction for the\ntemperature profile of new systems. This methodology would provide a novel and\nreliable tool for speeding up photothermal investigations and designing\nstate-of-the-art photothermal devices."
    },
    {
        "anchor": "Electrically switchable valley polarization, spin/valley filter, and\n  valve effects in transition-metal dichalcogenide monolayers interfaced with\n  two-dimensional ferromagnetic semiconductors: Electron valleys in transition-metal dichalcogenide monolayers drive novel\nphysics and allow designing multifunctional architectures for applications. We\npropose to manipulate the electron valleys in these systems for spin/valley\nfilter and valve devices through band engineering. Instead of the magnetic\nproximity effect that has been extensively used in previous studies, in our\nstrategy, the electron valleys are directly coupled to the spin-polarized\nstates of the two-dimensional ferromagnets. We find that this coupling results\nin a valley-selective gap opening due to the spin-momentum locking in the\ntransition-metal dichalcogenide monolayers. This physics gives rise to a\nvariety of unexpected electronic properties and phenomena including\nhalfmetallicity, electrically switchable valley polarization, spin/valley\nfilter and valve effects in the transition-metal dichalcogenide monolayers. We\nfurther demonstrate our idea in MoTe$_2$/CoCl$_2$ and\nCoCl$_2$/MoTe$_2$/CoCl$_2$ van der Waals heterojunctions based on\nfirst-principles calculations. Thus, our study provides a way of engineering\nthe electron valleys in transition-metal dichalcogenide monolayers for\nnew-concept devices.",
        "positive": "Sublattice-enriched tunability of bound states in second-order\n  topological insulators and superconductors: Bound states at sharp corners have been widely viewed as the hallmark of\ntwo-dimensional second-order topological insulators and superconductors. In\nthis work, we show that the existence of sublattice degrees of freedom can\nenrich the tunability of bound states on the boundary and hence lift the\nconstraint on their locations. We take the Kane-Mele model with\nhoneycomb-lattice structure to illustrate the underlying physics. With the\nintroduction of an in-plane exchange field to the model, we find that the\nboundary Dirac mass induced by the exchange field has a sensitive dependence on\nthe boundary sublattice termination. We find that the sensitive sublattice\ndependence can lead bound states to emerge at a specific type of boundary\ndefects named as sublattice domain walls if the exchange field is of\nferromagnetic nature, even in the absence of any sharp corner on the boundary.\nRemarkably, this sensitive dependence of the boundary Dirac mass on the\nboundary sublattice termination allows the positions of bound states to be\nmanipulated to any place on the boundary for an appropriately-designed sample.\nWith a further introduction of conventional s-wave superconductivity to the\nmodel, we find that, no matter whether the exchange field is ferromagnetic,\nantiferromagnetic, or ferrimagnetic, highly controllable Majorana zero modes\ncan be achieved at the sublattice domain walls. Our work reshapes the\nunderstanding of boundary physics in second-order topological phases, and\nmeanwhile opens potential avenues to realize highly controllable bound states\nfor potential applications."
    },
    {
        "anchor": "Cross-sectional imaging of individual layers and buried interfaces of\n  graphene-based heterostructures and superlattices: By stacking various two-dimensional (2D) atomic crystals [1] on top of each\nother, it is possible to create multilayer heterostructures and devices with\ndesigned electronic properties [2-5]. However, various adsorbates become\ntrapped between layers during their assembly, and this not only affects the\nresulting quality but also prevents the formation of a true artificial layered\ncrystal upheld by van der Waals interaction, creating instead a laminate glued\ntogether by contamination. Transmission electron microscopy (TEM) has shown\nthat graphene and boron nitride monolayers, the two best characterized 2D\ncrystals, are densely covered with hydrocarbons (even after thermal annealing\nin high vacuum) and exhibit only small clean patches suitable for atomic\nresolution imaging [6-10]. This observation seems detrimental for any realistic\nprospect of creating van der Waals materials and heterostructures with\natomically sharp interfaces. Here we employ cross sectional TEM to take a side\nview of several graphene-boron nitride heterostructures. We find that the\ntrapped hydrocarbons segregate into isolated pockets, leaving the interfaces\natomically clean. Moreover, we observe a clear correlation between interface\nroughness and the electronic quality of encapsulated graphene. This work proves\nthe concept of heterostructures assembled with atomic layer precision and\nprovides their first TEM images.",
        "positive": "Electrical transport properties of small diameter single-walled carbon\n  nanotubes aligned on ST-cut quartz substrates: A method is introduced to isolate and measure the electrical transport\nproperties of individual single-walled carbon nanotubes (SWNTs) aligned on an\nST-cut quartz, from room temperature down to 2 K. The diameter and chirality of\nthe measured SWNTs are accurately defined from Raman spectroscopy and atomic\nforce microscopy (AFM). A significant up-shift in the G-band of the resonance\nRaman spectra of the SWNTs is observed, which increases with increasing SWNTs\ndiameter, and indicates a strong interaction with the quartz substrate. A\nsemiconducting SWNT, with diameter 0.84 nm, shows Tomonaga-Luttinger liquid and\nCoulomb blockade behaviors at low temperatures. Another semiconducting SWNT,\nwith a thinner diameter of 0.68 nm, exhibits a transition from the\nsemiconducting state to an insulating state at low temperatures. These results\nelucidate some of the electrical properties of SWNTs in this unique\nconfiguration and help pave the way towards prospective device applications."
    },
    {
        "anchor": "Single-electron gap in the spectrum of twisted bilayer graphene: We investigate the gap in the single-electron spectrum of twisted bilayer\ngraphene. In a perfect infinite lattice of a twisted bilayer, the gap varies\nexponentially in response to weak changes of the twist angle. Such a large\nsensitivity makes theoretical predictions of the gap nearly impossible, since\nexperimentally the twist angle is always known with finite accuracy. To address\nthis issue, we numerically study finite clusters of twisted bilayer graphene.\nFor finite systems, changing the twist angle causes a gradual crossover between\ngapless and gapped regimes. The crossover occurs when the finite-size\nquantization energy becomes comparable to the matrix elements responsible for\nthe generation of the gap. We further argue that disorder scattering can induce\nsimilar crossover, in which the mean-free path plays the same role as the\nsystem size for the finite clusters. It is demonstrated that, to observe the\ngap experimentally, it is necessary to have a sample of suitable purity, and to\npossess the ability to tune the twist angle accurately.",
        "positive": "Thermoelectric study of dissipative quantum dot heat engines: This paper examines the thermoelectric response of a dissipative quantum dot\nheat engine based on the Anderson-Holstein model in two relevant operating\nlimits: (i) when the dot phonon modes are out of equilibrium, and (ii) when the\ndot phonon modes are strongly coupled to a heat bath. In the first case, a\ndetailed analysis of the physics related to the interplay between the quantum\ndot level quantization, the on-site Coulomb interaction and the electron-phonon\ncoupling on the thermoelectric performance reveals that an n-type heat engine\nperforms better than a p-type heat engine. In the second case, with the aid of\nthe dot temperature estimated by incorporating a {\\it{thermometer bath}}, it is\nshown that the dot temperature deviates from the bath temperature as\nelectron-phonon interaction becomes stronger. Consequently, it is demonstrated\nthat the dot temperature controls the direction of phonon heat currents,\nthereby influencing the thermoelectric performance. Finally, the conditions on\nthe maximum efficiency with varying phonon couplings between the dot and all\nthe other macroscopic bodies are analyzed in order to reveal the nature of the\noptimum junction."
    },
    {
        "anchor": "The nontrivial role of interfacial or film-thickness in a magnetic field\n  at a one-electron and a one-Composite Fermion level: By developing a canonical approach that is exact, physically transparent and\nsubtly different from standard methods, we present a systematic study with\nexact analytical calculations based on a Landau Level (LL) picture of the\nenergetics of a many-electron system in an interface (or film) and in the\npresence of a uniform and perpendicular magnetic field, by seriously taking\ninto account the finite thickness of the Quantum Well (QW) along the field. We\nfind internal phase transitions (i.e. at partial LL filling) for the global\nmagnetization and magnetic susceptibility that are not captured by other\napproaches, and that give rise to nontrivial corrections to the standard de\nHaas-van Alphen periods (but in a manner that reproduces the exact quantal\ndeviations from the semiclassical periodicity in the limit of the full 3D\nspace, a problem mostly discussed in astrophysical applications and which we\nindependently solve analytically as well for comparison). Additional features\nupon inclusion of Zeeman splitting are also found (such as certain energy\nminima that originate from the interplay of QW, Zeeman and LL Physics in the\nfull 3D problem), while a corresponding calculation in a Composite Fermion\npicture (with Lambda-Levels) leads to new predictions on magnetic response\nproperties of a fully-interacting electron liquid in a finite-thickness\ninterface; these exhibit a richer and more delicate structure than the mere\nmonotonic reduction of gaps with thickness reported long ago, a structure\npossibly detectable with present day technology. Finally, by pursuing the same\nline of reasoning for a topologically nontrivial system (with a relativistic\nspectrum, spin-orbit interactions and strong coupling between thickness and\nplanar motion) we find evidence that similar effects may be operative in the\ndimensionality crossover of 3D strong topological insulators to 2D topological\ninsulator quantum wells",
        "positive": "Resonant tunneling through superconducting double barrier structures in\n  graphene: We study resonant tunneling through a superconducting double barrier\nstructure in graphene as a function of the system parameters. At each barrier,\ndue to the proximity effect, an incident electron can either reflect as an\nelectron or a hole (specular as well as retro Andreev reflection in graphene).\nSimilarly, transport across the barriers can occur via electrons as well as via\nthe crossed (specular and/or retro) Andreev channel, where a hole is\ntransmitted nonlocally to the other lead. In this geometry, in the subgap\nregime, we find resonant suppression of Andreev reflection at certain energies,\ndue to the formation of Andreev bound levels between the two superconducting\nbarriers, where the transmission probability T for electrons incident on the\ndouble barrier structure becomes unity. The evolution of the transport through\nthe superconducting double barrier geometry as a function of the incident\nenergy for various angles of incidence shows the damping of the resonance as\nnormal reflection between the barriers increases."
    },
    {
        "anchor": "Disorder induced transverse delocalisation in ropes of carbon nanotubes: A rope of carbon nanotubes is constituted of an array of parallel single wall\nnanotubes with nearly identical diameters. In most cases the individual\nnanotubes within a rope have different helicities and 1/3 of them are metallic.\nIn the absence of disorder within the tubes, the intertube electronic transfer\nis negligeable because of the longitudinal wave vector mismatch between\nneighboring tubes of different helicities. The rope can then be considered as a\nnumber of parallel independent ballistic nanotubes. On the other hand, the\npresence of disorder within the tubes favors the intertube electronic transfer.\nThis is first shown using a very simple model where disorder is treated\nperturbatively inspired by the work in reference \\cite{maarouf00}.\n  We then present numerical simulations on a tight binding model of a rope.\nDisorder induced transverse delocalisation shows up as a spectacular increase\nof the sensitivity to the transverse boundary conditions in the presence of\nsmall disorder. This is accompanied by an increase of the longitudinal\nlocalisation length. Implications on the nature of electronic transport within\na rope of carbon nanotubes are discussed.",
        "positive": "Hall Effect in Granular Metals: Weak Localization Corrections: We study the effects of localization on the Hall transport in a granular\nsystem at large tunneling conductance $g_{T}\\gg 1$ corresponding to the\nmetallic regime. We show that the first-order in 1/g_T weak localization\ncorrection to Hall resistivity of a two- or three-dimensional granular array\nvanishes identically, $\\de \\rho_{xy}^{WL}=0$. This result is in agreement with\nthe one for ordinary disordered metals. Being due to an exact cancellation, our\nresult holds for arbitrary relevant values of temperature T and magnetic field\nH, both in the ``homogeneous'' regime of very low T and H corresponding to\nordinary disordered metals and in the ``structure-dependent'' regime of higher\nvalues of T or H."
    },
    {
        "anchor": "Scattering theory of interface resistance in magnetic multilayers: The scattering theory of transport has to be applied with care in a diffuse\nenvironment. Here we discuss how the scattering matrices of heterointerfaces\ncan be used to compute interface resistances of dirty magnetic multilayers.\nFirst principles calculations of these interface resistances agree well with\nexperiments in the CPP (current perpendicular to the interface plane)\nconfiguration.",
        "positive": "Band gap reconstruction at the interface between black phosphorus and a\n  gold electrode: We experimentally investigate charge transport through the interface between\na gold electrode and a black phosphorus single crystal. The experimental\n$dI/dV(V)$ curves are characterized by well developed zero-bias conductance\npeak and two strongly different branches. We find that two branches of\nasymmetric $dI/dV(V)$ curves correspond to different band gap limits, which is\nconsistent with the theoretically predicted band gap reconstruction at the\nsurface of black phosphorus under electric field. This conclusion is confirmed\nby experimental comparison with the symmetric curves for narrow-gap (WTe$_2$)\nand wide-gap (GaSe) metal-semiconductor structures. In addition, we demonstrate\np-type dopants redistribution at high bias voltages of different sign, which\nopens a way to use the interface structures with black phosphorus in resistive\nmemory applications."
    },
    {
        "anchor": "Kinetics of local $\"$magnetic$\"$ moment and non-stationary\n  spin-polarized current in the single impurity Anderson-model: We perform theoretical investigation of the localized state dynamics in the\npresence of interaction with the reservoir and Coulomb correlations. We analyze\nkinetic equations for electron occupation numbers with different spins taking\ninto account high order correlation functions for the localized electrons. We\nreveal that in the stationary state electron occupation numbers with the\nopposite spins always have the same value - the stationary state is a\n$\"$paramagnetic$\"$ one. $\"$Magnetic$\"$ properties can appear only in the\nnon-stationary characteristics of the single-impurity Anderson model and in the\ndynamics of the localized electrons second order correlation functions. We\nfound, that for deep energy levels and strong Coulomb correlations, relaxation\ntime for initial $\"$magnetic$\"$ state can be several orders larger than for\n$\"$paramagnetic$\"$ one. So, long-living $\"$magnetic$\"$ moment can exist in the\nsystem. We also found non-stationary spin polarized currents flowing in\nopposite directions for the different spins in the particular time interval.",
        "positive": "Quantum non-local theory of topological Fermi arc plasmons in Weyl\n  semimetals: The surface of a Weyl semimetal (WSM) displays Fermi arcs, i.e. disjoint\nsegments of a two-dimensional Fermi contour. We present a quantum-mechanical\nnon-local theory of chiral Fermi arc plasmons in WSMs with broken time-reversal\nsymmetry. These are collective excitations constructed from topological Fermi\narc and bulk electron states and arising from electron-electron interactions,\nwhich are treated in the realm of the random phase approximation. Our theory\nincludes quantum effects associated with the penetration of the Fermi arc\nsurface states into the bulk and dissipation, which is intrinsically non-local\nin nature and arises from decay processes mainly involving bulk electron-hole\npair excitations."
    },
    {
        "anchor": "Setup for shot noise measurements in carbon nanotubes: We have constructed a noise measurement setup for high impedance carbon\nnanotube samples. Our setup, working in the frequency range of 600 - 900 MHz,\ntakes advantage of the fact that the shot noise power is reasonably large for\nhigh impedance sources so that relatively large, fixed non-matching conditions\ncan be tolerated.",
        "positive": "Effect of spin-orbit coupling on zero-conductance resonances in\n  asymmetrically coupled one-dimensional rings: The influence of Rashba spin-orbit coupling on zero conductance resonances\nappearing in one dimensional ring asymmetrically coupled to two leads is\ninvestigated. For this purpose, the transmission function of the corresponding\none-electron scattering problem is derived analytically and analyzed in the\ncomplex energy plane with focus on the zero-pole structure characteristic of\ntransmission (anti)resonances. The lifting of real conductance zeros due to\nspin-orbit coupling in the asymmetric Aharonov-Casher (AC) ring is related to\nthe breaking of spin reversal symmetry in analogy to the time-reversal symmetry\nbreaking in the asymmetric Aharonov-Bohm (AB) ring."
    },
    {
        "anchor": "Coherent transport through a resonant level coupled to random-matrix\n  leads: We study the transport through a resonant level coupled to two leads with the\nlatter being described by Wigner's random matrices. By taking appropriate\nthermodynamic limit before taking the long time limit, we obtain the stationary\ncurrent as a function of voltage bias. The I-V curve is similar to that of\nsingle impurity Anderson model. On the other hand, the current matrix and\ninitial density matrix in our model look like random matrices in the eigenbasis\nof Hamiltonian. They satisfy the description of eigenstate thermalization\nhypothesis (ETH) and nonequilibrium steady state hypothesis (NESSH),\nrespectively. A statistical formula of current has been derived based on ETH\nand NESSH (J. Stat. Mech.: Theo. Exp., 093105 (2017)). We check this formula in\nour model and find it to predict the stationary current to a high precision.\nThe shape of I-V curve is explained by the peak structure in the characteristic\nfunction of NESSH, which is reminiscent of the transmission coefficient.",
        "positive": "Spin and charge transport in U-shaped one-dimensional channels with\n  spin-orbit couplings: A general form of the Hamiltonian for electrons confined to a curved\none-dimensional (1D) channel with spin-orbit coupling (SOC) linear in momentum\nis rederived and is applied to a U-shaped channel. Discretizing the derived\ncontinuous 1D Hamiltonian to a tight-binding version, the Landauer-Keldysh\nformalism (LKF) for nonequilibrium transport can be applied. Spin transport\nthrough the U-channel based on the LKF is compared with previous quantum\nmechanical approaches. The role of a curvature-induced geometric potential\nwhich was previously neglected in the literature of the ring issue is also\nrevisited. Transport regimes between nonadiabatic, corresponding to weak SOC or\nsharp turn, and adiabatic, corresponding to strong SOC or smooth turn, is\ndiscussed. Based on the LKF, interesting charge and spin transport properties\nare further revealed. For the charge transport, the interplay between the\nRashba and the linear Dresselhaus (001) SOCs leads to an additional modulation\nto the local charge density in the half-ring part of the U-channel, which is\nshown to originate from the angle-dependent spin-orbit potential. For the spin\ntransport, theoretically predicted eigenstates of the Rashba rings, Dresselhaus\nrings, and the persistent spin-helix state are numerically tested by the\npresent quantum transport calculation."
    },
    {
        "anchor": "Magnetic control of dipolaritons in quantum dots: Dipolaritons are quasiparticles that arise in coupled quantum wells embedded\nin a microcavity, they are a superposition of a photon, a direct exciton and an\nindirect exciton. We propose the existence of dipolaritons in a system of two\ncoupled quantum dots inside a microcavity in direct analogy with the quantum\nwell case and find that, despite some similarities, dipolaritons in quantum\ndots have different properties and can lead to true dark polariton states. We\nuse a finite system theory to study the effects of the magnetic field on the\nsystem, including the emission, and find that it can be used as a control\nparameter of the properties of excitons and dipolaritons, and the overall\nmagnetic behaviour of the structure.",
        "positive": "Nonlocal transport near the charge neutrality point in a two-dimensional\n  electron-hole system: Nonlocal resistance is studied in a two-dimensional system with a\nsimultaneous presence of electrons and holes in a 20 nm HgTe quantum well. A\nlarge nonlocal electric response is found near the charge neutrality point\n(CNP) in the presence of a perpendicular magnetic field. We attribute the\nobserved nonlocality to the edge state transport via counter propagating chiral\nmodes similar to the quantum spin Hall effect at zero magnetic field and\ngraphene near Landau filling factor $\\nu=0$"
    },
    {
        "anchor": "Visualizing the in-gap states in domain boundaries of ultra-thin\n  topological insulator films: Ultra-thin topological insulators provide a platform of realizing many exotic\nphenomena such a Quantum spin Hall effect, Quantum anomalous Hall effect, etc.\nThese effects or states are characterized by quantized transport behavior of\nedge states. Experimentally, although these states have been realized in\nvarious systems, the temperature for the edge states to be the dominating\nchannel in transport is extremely low, contrary to the fact that the bulk gap\nis usually in the order of a few tens of milli-electron volts. There must be\nother in-gap conduction channels that won't freeze out till a much low\ntemperature. Here we grow ultra-thin topological insulator Bi2Te3 and Sb2Te3\nfilms by molecular beam epitaxy and investigate the structures of domain\nboundaries in these films. By scanning tunneling microscopy and spectroscopy we\nfind that the domain boundaries with large rotation angles have pronounced\nin-gap bound states, through which one dimensional conduction channels are\nsuggested to form as visualized by spatially resolved spectroscopy. Our work\nindicates the critical role played by domain boundaries in degrading the\ntransport properties.",
        "positive": "Materials design from non-equilibrium steady states: driven graphene as\n  a tunable semiconductor with topological properties: Controlling the properties of materials by driving them out of equilibrium is\nan exciting prospect that has only recently begun to be explored. In this paper\nwe give a striking theoretical example of such materials design: a tunable gap\nin monolayer graphene is generated by exciting a particular optical phonon. We\nshow that the system reaches a steady state whose transport properties are the\nsame as if the system had a static electronic gap, controllable by the driving\namplitude. Moreover, the steady state displays topological phenomena: there are\nchiral edge currents, which circulate a fractional charge e/2 per rotation\ncycle, with frequency set by the optical phonon frequency."
    },
    {
        "anchor": "Exact mode volume and Purcell factor of open optical systems: The Purcell factor quantifies the change of the radiative decay of a dipole\nin an electromagnetic environment relative to free space. Designing this factor\nis at the heart of photonics technology, striving to develop ever smaller or\nless lossy optical resonators. The Purcell factor can be expressed using the\nelectromagnetic eigenmodes of the resonators, introducing the notion of a mode\nvolume for each mode. This approach allows to use an analytic treatment,\nconsisting only of sums over eigenmode resonances, a so-called spectral\nrepresentation. We show in the present work that the expressions for the mode\nvolumes known and used in literature are only approximately valid for modes of\nhigh quality factor, while in general they are incorrect. We rectify this\nissue, introducing the exact normalization of modes. We present an analytic\ntheory of the Purcell effect based on the exact mode normalization and\nresulting effective mode volume. We use a homogeneous dielectric sphere in\nvacuum, which is analytically solvable, to exemplify these findings.",
        "positive": "Quantum frustration of dissipation by a spin bath: We investigate the evolution of a central spin coupled to a spin bath without\ninternal dynamics. We compare the cases where the bath couples to one or two\ncomponents of the spin. It is found that the central spin dynamics is enhanced\nin the latter case, which may be interpreted as a frustration of dissipation.\nHowever, the quantum purity of the spin decays fast in both scenarios. We\nconclude that symmetric coupling of the bath to two orthogonal components of\nthe spin inhibits dissipation but not decoherence."
    },
    {
        "anchor": "Nonequilibrium processes from Generalised Langevin Equations: realistic\n  nanoscale systems connected to two thermal baths: We extend the Generalised Langevin Equation (GLE) method [Phys. Rev. B 89,\n134303 (2014)] to model a central classical region connected to two realistic\nthermal baths at two different temperatures. In such nonequilibrium conditions\na heat flow is established, via the central system, in between the two baths.\nThe GLE-2B (GLE two baths) scheme permits us to have a realistic description of\nboth the dissipative central system and its surrounding baths. Following the\noriginal GLE approach, the extended Langevin dynamics scheme is modified to\ntake into account two sets of auxiliary degrees of freedom corresponding to the\nmapping of the vibrational properties of each bath. These auxiliary variables\nare then used to solve the non-Markovian dissipative dynamics of the central\nregion. The resulting algorithm is used to study a model of a short Al nanowire\nconnected to two baths. The results of the simulations using the GLE-2B\napproach are compared to the results of other simulations that were carried out\nusing standard thermostatting approaches (based on Markovian Langevin and\nNose-Hoover thermostats). We concentrate on the steady state regime and study\nthe establishment of a local temperature profile within the system. The\nconditions for obtaining a flat profile or a temperature gradient are examined\nin detail, in agreement with earlier studies. The results show that the GLE-2B\napproach is able to treat, within a single scheme, two widely different thermal\ntransport regimes, i.e. ballistic systems, with no temperature gradient, and\ndiffusive systems with a temperature gradient.",
        "positive": "CdSe/ZnSe quantum dot with a single Mn$^{2+}$ ion - a new system for a\n  single spin manipulation: We present a magneto-optical study of individual self-assembled CdSe/ZnSe\nquantum dots doped with single Mn$^{2+}$ ions. Properties of the studied dots\nare analyzed analogously to more explored system of Mn-doped CdTe/ZnTe dots.\nCharacteristic sixfold splitting of the neutral exciton emission line as well\nas its evolution in the magnetic field are described using a spin Hamiltonian\nmodel. Dynamics of both exciton recombination and Mn$^{2+}$ spin relaxation are\nextracted from a series of time-resolved experiments. Presence of a single\ndopant is shown not to affect the average excitonic lifetime measured for a\nnumber of nonmagnetic and Mn-doped dots. On the other hand, non-resonant\npumping is demonstrated to depolarize the Mn$^{2+}$ spin in a quantum dot\nplaced in external magnetic field. This effect is utilized to determine the ion\nspin relaxation time in the dark."
    },
    {
        "anchor": "Quantum criticality and minimal conductivity in graphene with long-range\n  disorder: We consider the conductivity $\\sigma_{xx}$ of graphene with negligible\nintervalley scattering at half filling. We derive the effective field theory,\nwhich, for the case of a potential disorder, is a symplectic-class\n$\\sigma$-model including a topological term with $\\theta=\\pi$. As a\nconsequence, the system is at a quantum critical point with a universal value\nof the conductivity of the order of $e^2/h$. When the effective time reversal\nsymmetry is broken, the symmetry class becomes unitary, and $\\sigma_{xx}$\nacquires the value characteristic for the quantum Hall transition.",
        "positive": "Shear viscosity in interacting two-dimensional Fermi liquids: In interaction-dominated two-dimensional electron gases at intermediate\ntemperatures, electron transport is not diffusive as in the conventional Drude\npicture but instead hydrodynamic. The relevant transport coefficient in this\nregime is the shear viscosity. Here, we develop a numerically exact basis\nexpansion to solve the Fermi liquid equation, and apply it to compute the shear\nviscosity of the electron gas with screened Coulomb interactions. Our\ncalculations are valid at all temperatures and in particular describe the\nresponse beyond the asymptotic low-temperature limit, where perturbative\napproaches exist. We show that even in this low-temperature limit, there is a\nnonanalytic exchange contribution to the shear viscosity, highlighting the need\nfor a full nonperturbative solution of the Fermi liquid equation. We hope that\nthe techniques developed in this work will serve as a platform to determine the\nresponse of interacting Fermi liquids."
    },
    {
        "anchor": "Poissonian tunneling through an extended impurity in the quantum Hall\n  effect: We consider transport in the Poissonian regime between edge states in the\nquantum Hall effect. The backscattering potential is assumed to be arbitrary,\nas it allows for multiple tunneling paths. We show that the Schottky relation\nbetween the backscattering current and noise can be established in full\ngenerality: the Fano factor corresponds to the electron charge (the\nquasiparticle charge) in the integer (fractional) quantum Hall effect, as in\nthe case of purely local tunneling. We derive an analytical expression for the\nbackscattering current, which can be written as that of a local tunneling\ncurrent, albeit with a renormalized tunneling amplitude which depends on the\nvoltage bias. We apply our results to a separable tunneling amplitude which can\nrepresent an extended point contact in the integer or in the fractional quantum\nHall effect. We show that the differential conductance of an extended quantum\npoint contact is suppressed by the interference between tunneling paths, and it\nhas an anomalous dependence with respect to the bias voltage.",
        "positive": "Off-resonant coupling between a single quantum dot and a nanobeam\n  photonic crystal cavity: We demonstrate off-resonant coupling between a single quantum dot and a\nnanobeam photonic crystal cavity, under resonant excitation of the quantum dot\nor the cavity. These results are consistent with previous descriptions of\noff-resonant coupling as an incoherent phonon-mediated process. The extension\nof this phenomenon to a nanobeam photonic crystal cavity presents interesting\npossibilities for coherent control of this interaction by tailoring the phonon\ndensity of states."
    },
    {
        "anchor": "Thermal near-field energy density and LDOS in topological 1D SSH chains\n  and 2D SSH lattices of plasmonic nanoparticles: We derive a general expression for electric and magnetic part of the\nnear-field energy density of $N$ dipoles of temperatures $T_1, \\ldots, T_N$\nimmersed in a background field having a different temperature $T_b$. In\ncontrast to former expressions this inclusion of the background field allows\nfor determining the energy density of heated or cooled isotropic dipolar\nobjects within an arbitrary environment which is thermalized at a different\ntemperature. Furthermore, we show how the energy density is related to the\nlocal density of states. We use this general expression to study the near-field\nenhanced energy density at the edges and corners of 1D Su-Schrieffer-Heeger\nchains and 2D Su-Schrieffer-Heeger lattices of plasmonic InSb nanoparticles\nwhen the phase transition from a topological trivial to a topological\nnon-trivial state is made. We discuss the robustness of these modes when adding\ndefects and the possibility to measure the topological edge and corner modes.",
        "positive": "Collective Coordinate Descriptions of Magnetic Domain Wall Motion in\n  Perpendicularly Magnetized Nanostructures under the Application of In-plane\n  Fields: Manipulation of magnetic domain walls can be used to improve the capabilities\nof the next generation of memory and sensing devices. Materials of recent\ninterest for such devices include heterostructures of ultrathin ferromagnets\nsandwiched between a heavy metal and an oxide, where spin-orbit coupling and\nbroken inversion symmetry give rise to the Dzyaloshinskii-Moriya interaction\n(DMI), stabilizing chiral domain walls. The efficiency of the motion of these\nchiral domain walls may be controlled using in-plane magnetic fields. This\nproperty has been used for measurement of DMI strength. While micromagnetic\nsimulations are able to accurately predict domain wall motion under in-plane\nfields in these materials, collective coordinate models such as the $q-\\phi$\nand $q-\\phi-\\chi$ models fail to reproduce the micromagnetic results. In this\ntheoretical work, we present a set of extended collective coordinate models\nincluding canting in the domains, which better reproduce micromagnetic results,\nand helps us better understand the effect of in-plane fields on magnetic domain\nwalls. These models are used in conjunction with micromagnetic simulations to\nidentify critical points observed in the motion of the domain walls driven by\nout-of-plane magnetic fields, and electric current under magnetic in-plane\nfields. Our new models and results help in the development of future domain\nwall based devices based on perpendicularly magnetized materials."
    },
    {
        "anchor": "Graphene Transverse Electric Surface Plasmon Detection using\n  Nonreciprocity Modal Discrimination: We present a magnetically biased graphene-ferrite structure discriminating\nthe TE and TM plasmonic modes of graphene. In this structure, the graphene TM\nplasmons interact reciprocally with the structure. In contrast, the graphene TE\nplasmons exhibit nonreciprocity. This nonreciprocity is manifested in\nunidirectional TE propagation in a frequency band close to the interband\nthreshold frequency. The proposed structure provides a unique platform for the\nexperimental demonstration of the unusual existence of the TE plasmonic mode in\ngraphene.",
        "positive": "Origin of conductivity cross over in entangled multi-walled carbon\n  nanotube network filled by iron: A realistic transport model showing the interplay of the hopping transport\nbetween the outer shells of iron filled entangled multi-walled carbon nanotubes\n(MWNT) and the diffusive transport through the inner part of the tubes, as a\nfunction of the filling percentage, is developed. This model is based on\nlow-temperature electrical resistivity and magneto-resistance (MR)\nmeasurements. The conductivity at low temperatures showed a crossover from\nEfros-Shklovski (E-S) variable range hopping (VRH) to Mott VRH in 3 dimensions\n(3D) between the neighboring tubes as the iron weight percentage is increased\nfrom 11% to 19% in the MWNTs. The MR in the hopping regime is strongly\ndependent on temperature as well as magnetic field and shows both positive and\nnegative signs, which are discussed in terms of wave function shrinkage and\nquantum interference effects, respectively. A further increase of the iron\npercentage from 19% to 31% gives a conductivity crossover from Mott VRH to 3D\nweak localization (WL). This change is ascribed to the formation of long iron\nnanowires at the core of the nanotubes, which yields a long dephasing length\n(e.g. 30 nm) at the lowest measured temperature. Although the overall transport\nin this network is described by a 3D WL model, the weak temperature dependence\nof inelastic scattering length expressed as L_phi ~T^-0.3 suggests the\npossibility for the presence of one-dimensional channels in the network due to\nthe formation of long Fe nanowires inside the tubes, which might introduce an\nalignment in the random structure."
    },
    {
        "anchor": "Intrinsic nonlinear Hall effect and gate-switchable Berry curvature\n  sliding in twisted bilayer graphene: Though the observation of the quantum anomalous Hall effect and nonlocal\ntransport response reveals nontrivial band topology governed by the Berry\ncurvature in twisted bilayer graphene, some recent works reported nonlinear\nHall signals in graphene superlattices that are caused by the extrinsic\ndisorder scattering rather than the intrinsic Berry curvature dipole moment. In\nthis work, we report a Berry curvature dipole induced intrinsic nonlinear Hall\neffect in high-quality twisted bilayer graphene devices. We also find that the\napplication of the displacement field substantially changes the direction and\namplitude of the nonlinear Hall voltages, as a result of a field-induced\nsliding of the Berry curvature hotspots. Our work not only proves that the\nBerry curvature dipole could play a dominant role in generating the intrinsic\nnonlinear Hall signal in graphene superlattices with low disorder densities,\nbut also demonstrates twisted bilayer graphene to be a sensitive and\nfine-tunable platform for second harmonic generation and rectification.",
        "positive": "Influence of interlayer asymmetry on magneto-spectroscopy of bilayer\n  graphene: We present a self-consistent calculation of the interlayer asymmetry in\nbilayer graphene caused by an applied electric field in magnetic fields. We\nshow how this asymmetry influences the Landau level spectrum in bilayer\ngraphene and the observable inter-Landau level transitions when they are\nstudied as a function of high magnetic field at fixed filling factor as\nmeasured experimentally by E.A. Henriksen et al., Phys. Rev. Lett. 100 (2008),\n087403. We also analyze the magneto-optical spectra of bilayer flakes in the\nphoton-energy range corresponding to transitions between degenerate and split\nbands of bilayers."
    },
    {
        "anchor": "Topological properties of subsystem-symmetry-protected edge states in an\n  extended quasi-one-dimensional dimerized lattice: We investigate theoretically the topological properties of dimerized\nquasi-one-dimensional (1D) lattice comprising of multi legs $(L)$ as well as\nmulti sublattices $(R)$. The system has main and subsidiary exchange\nsymmetries. In the basis of latter one, the system can be divided into $L$ 1D\nsubsystems each of which corresponds to a generalized $SSH_R$ model having $R$\nsublattices and on-site potentials. Chiral symmetry is absent in all subsystems\nexcept when the axis of main exchange symmetry coincides on the central chain.\nWe find that the system may host zero- and finite-energy topological edge\nstates. The existence of zero-energy edge state requires a certain relation\nbetween the number of legs and sublattices. As such, different topological\nphases, protected by subsystem symmetry, including zero-energy edge states in\nthe main gap, no zero-energy edge states, and zero-energy edge states in the\nbulk states are characterized. Despite the classification symmetry of the\nsystem belongs to $BDI$ but each subsystem falls in either $AI$ or $BDI$\nsymmetry class.",
        "positive": "Electron-optical phonon coupling in suspended bilayer graphene: Using electrical transport experiments and shot noise thermometry, we\ninvestigate electron-phonon heat transfer rate in a suspended bilayer graphene.\nContrary to monolayer graphene with heat flow via three-body supercollision\nscattering, we find that regular electron - optical phonon scattering in\nbilayer graphene provides the dominant scattering process at electron energies\n$ \\gtrsim 0.15$ eV. We determine the strength of these intrinsic heat flow\nprocesses of bilayer graphene and find good agreement with theoretical\nestimates when both zone edge and zone center optical phonons are taken into\naccount."
    },
    {
        "anchor": "Kondo Effect in Defect-bound Quantum Dots Coupled to NbSe$_2$: We report the fabrication of a van der Waals tunneling device hosting a\ndefect-bound quantum dot coupled to NbSe$_2$. We find that upon application of\nmagnetic field, the device exhibits a zero-bias conductance peak. The peak,\nwhich splits at higher fields, is associated with a Kondo effect. At the same\ntime, the junction retains conventional quasiparticle tunneling features at\nfinite bias. Such coexistence of a superconducting gap and a Kondo effect are\nunusual, and are explained by noting the two-gap nature of the superconducting\nstate of NbSe$_2$, where a magnetic field suppresses the low energy gap\nassociated with the Se band. Our data shows that van der Waals architectures,\nand defect-bound dots in them, can serve as a novel and effective platform for\ninvestigating the interplay of Kondo screening and superconducting pairing in\nunconventional superconductors.",
        "positive": "New approach to exact extraction of piezoresistance coefficient: The extension of piezoresistance coefficient extraction method was proposed,\nfor protection from errors in estimation of the thickness of the test structure\nmembrane. This new approach requires finding models of elements of matrix of\nintegrated stresses as functions of the membrane thickness. Additionally, two\ntest structures with different thickness of the membrane have to be used. This\nimproved method gives the more credible estimation of piezoresistance\ncoefficients $\\pi_L$ and $\\pi_T$ and the thickness of the membranes of the used\ntest structures."
    },
    {
        "anchor": "Spin fluctuations in quantized transport of magnetic topological\n  insulators: In magnetic topological insulators, quantized electronic transport is\ninterwined with spontaneous magnetic ordering, as magnetization controls band\ngaps, hence band topology, through the exchange interaction. We show that\nconsidering the exchange gaps at the mean-field level is inadequate to predict\nphase transitions between electronic states of distinct topology. Thermal spin\nfluctuations disturbing the magnetization can act as frozen disorders that\nstrongly scatter electrons, reducing the onset temperature of quantized\ntransport appreciably even in the absence of structural impurities. This\neffect, which has hitherto been overlooked, provides an alternative explanation\nof recent experiments on intrinsic magnetic topological insulators.",
        "positive": "Challenges in molecular dynamics simulations of heat exchange statistics: We study heat exchange in temperature-biased metal-molecule-metal molecular\njunctions by employing the LAMMPS atomic molecular dynamics simulator.\nGenerating the nonequilibrium steady state with Langevin thermostats at the\nboundaries of the junction, we show that the {\\it average} heat current across\na gold-alkanedithiol-gold nanojunction behaves correctly-physically, with the\nthermal conductance value matching the literature. In contrast, the {\\it full\nprobability distribution function} for heat exchange, as generated by the\nsimulator, violates the fundamental fluctuation symmetry for entropy\nproduction. We trace this failure back to the implementation of the thermostats\nand the expression used to calculate the heat exchange. To rectify this issue\nand produce the correct statistics, we introduce single-atom thermostats as an\nalternative to conventional many-atom thermostats. Once averaging heat exchange\nover the hot and cold thermostats, this approach successfully generates the\ncorrect probability distribution function, which we use to study the behavior\nof both the average heat current and its noise. We further examine the\nthermodynamic uncertainty relation in the molecular junction and show that it\nholds, albeit demonstrating nontrivial trends. Our study points to the need to\ncarefully implement nonequilibrium molecular dynamics solvers in atomistic\nsimulation software tools for future investigations of noise phenomena in\nthermal transport."
    },
    {
        "anchor": "Thermal radiative energy exchange between a closely-spaced linear chain\n  of spheres and its environment: In this work, we present expressions for radiative heat transfer between\npairs of spheres in a linear chain and between individual spheres and their\nenvironment. The expressions are valid for coated spheres of arbitrary size,\nspacing, and isotropic optical properties. The spheres may be small and\nclosely-spaced, which violates the assumptions foundational to classical\nradiative transfer. We validate our results against existing formulations of\nradiative heat transfer, namely the thermal discrete dipole and boundary\nelement methods. Our results have important implications for the modeling and\ninterpretation of near-field radiative heat transfer experiments between\nspherical bodies.",
        "positive": "Spreading and localization of wavepackets in disordered wires in a\n  magnetic field: We study the diffusive and localization properties of wavepackets in\ndisordered wires in a magnetic field. In contrast to a recent supersymmetry\napproach our numerical results show that the decay rate of the steady state\nchanges {\\em smoothly} at the crossover from preserved to broken time-reversal\nsymmetry. Scaling and fluctuation properties are also analyzed and a formula,\nwhich was derived analytically only in the pure symmetry cases is shown to\ndescribe also the steady state wavefunction at the crossover regime. Finally,\nwe present a scaling for the variance of the packet which shows again a smooth\ntransition due to the magnetic field."
    },
    {
        "anchor": "A polariton electric field sensor: We experimentally demonstrate a dipolar polariton based electric field\nsensor. We tune and optimize the sensitivity of the sensor by varying the\ndipole moment of polaritons. We show polariton interactions play an important\nrole in determining the conditions for optimal electric field sensing, and\nachieve a sensitivity of 0.12 V-m$^{-1}$-Hz$^{-0.5}$. Finally we apply the\nsensor to illustrate that excitation of polaritons modify the electric field in\na spatial region much larger than the optical excitation spot.",
        "positive": "Keldysh field theory of dynamical exciton condensation transitions in\n  nonequilibrium electron-hole bilayers: Recent experiments have realized steady-state electrical injection of\ninterlayer excitons in electron-hole bilayers subject to a large bias voltage.\nIn the ideal case in which interlayer tunneling is negligibly weak, the system\nis in quasi-equilibrium with a reduced effective band gap. Interlayer tunneling\nintroduces a current and drives the system out of equilibrium. In this work we\nderive a nonequilibrium field theory description of interlayer excitons in\nbiased electron-hole bilayers. In the large bias limit, we find that p-wave\ninterlayer tunneling reduces the effective band gap and increases the effective\ntemperature for intervalley excitons. We discuss possible experimental\nimplications for InAs/GaSb quantum wells and transition metal dichalcogenide\nbilayers."
    },
    {
        "anchor": "Chiral Magnetic Effect due to Inhomogeneous Magnetic Fields in\n  Noncentrosymmetric Weyl Semimetals: The chiral magnetic effect is a phenomenon where an electromagnetic current\nis generated along a magnetic field. Recently, in nonequilibrium systems,\nnegative longitudinal magnetoresistance has been observed experimentally in\nDirac/Weyl semimetals, which provides evidence for the chiral magnetic effect\nas a nonequilibrium current. On the other hand, the emergence of the chiral\nmagnetic effect as an equilibrium current is still controversial. We propose a\npossible realization of the chiral magnetic effect as an equilibrium current\nusing inhomogeneous magnetic fields. By employing tight-binding calculations\nand linear response theory, we demonstrate that a finite current density is\ngenerated by inhomogeneous magnetic fields, while the spatial integration of\nthe current is equal to zero, which is consistent with the so-called \"no-go\ntheorem\" of the chiral magnetic effect in real lattice systems. Moreover, we\npropose an experimental setup to detect the effect in Weyl semimetal materials.",
        "positive": "Helicoidal excitonic phase in an electron-hole double layer system: We propose helicoidal excitonic phase in a Coulomb-coupled two-dimensional\nelectron-hole double layer (EHDL) system with relativistic spin-orbit\ninteraction. Previously, it was demonstrated that layered InAs/AlSb/GaInSb\nheterostructure is an ideal experimental platform for searching excitonic\ncondensate phases, while its electron layer has non-negligible Rashba\ninteraction. We clarify that due to the Rashba term, the spin-triplet (spin-1)\nexciton field in the EHDL system forms a helicoidal structure and the helicoid\nplane can be controlled by an in-plane Zeeman field. We show that due to small\nbut finite Dirac term in the heavy hole layer the helicoidal structure of the\nexcitonic field under the in-plane field results in a helicoidal {\\it magnetic}\norder in the electron layer. Based on linearization analyses, we further\ncalculate momentum-energy dispersions of low-energy Goldstone modes in the\nhelicoidal excitonic phase. We discuss possible experimental probes of the\nexcitonic phase in the EHDL system."
    },
    {
        "anchor": "Tuning Electronic and Magnetic Properties of Early Transition Metal\n  Dichalcogenides via Tensile Strain: We have performed a systematic first-principles study of the effect of\ntensile strains on the electronic properties of early transition-metal\ndichalcogenide (TMDC) monolayers MX2 (M = Sc, Ti, Zr, Hf, Ta, Cr; X = S, Se,\nand Te). Our density-functional theory (DFT) calculations suggest that the\ntensile strain can significantly affect the electronic properties of many early\nTMDCs in general and the electronic bandgap in particular. For group IVB TMDCs\n(TiX2, ZrX2, HfX2), the bandgap increases with the tensile strain, but for ZrX2\nand HfX2 (X=S, Se), the bandgap starts to decrease at strain 6% to 8%. For the\ngroup-VB TMDCs (TaX2), the tensile strain can either induce the ferromagnetism\nor enhance the existing ferromagnetism. For the group-VIB TMDCs (CrX2) the\ndirect-to-indirect bandgap transition is seen upon application of the tensile\nstrain, except CrTe2 whose bandgap decreases with the tensile strain even\nthough the direct character of its bandgap is retained. Lastly, for the\ngroup-IIIB TMDCs (ScX2) in the T metallic phase, we find that the tensile\nstrain has little effect on their electronic and magnetic properties. Our study\nsuggests that strain engineering is an effective approach to modify electronic\nand magnetic properties of most early TMDC monolayers, thereby opening an\nalternative way for future optoelectronic and spintronic applications.",
        "positive": "Diffusion thermopower of (Ga,Mn)As/GaAs tunnel junctions: We report the observation of tunneling anisotropic magnetothermopower, a\nvoltage response to a temperature difference across an interface between a\nnormal and a magnetic semiconductor. The resulting voltage is related to the\nenergy derivative of the density of states in the magnetic material, and thus\nhas a strongly anisotropic response to the direction of magnetization in the\nmaterial. The effect will have relevance to the operation of semiconductor\nspintronic devices, and may indeed already play a role in correctly\ninterpreting the details of some earlier spin injection studies."
    },
    {
        "anchor": "Quantum Transport through Nanostructures with Orbital Degeneracies: Geometric symmetries cause orbital degeneracies in a molecule's spectrum. In\na single-molecule junction, these degeneracies are lifted by various\nsymmetry-breaking effects. We study quantum transport through such\nnanostructures with an almost degenerate spectrum. We show that the master\nequation for the reduced density matrix must be derived within the\nsingular-coupling limit as opposed to the conventional weak-coupling limit.\nThis results in signatures of the density matrix's off-diagonal elements in the\ntransport characteristics.",
        "positive": "Probing the Evolution of Electron Spin Wavefunction of NV Center in\n  diamond via Pressure Tuning: Understanding the profile of a qubit's wavefunction is key to its quantum\napplications. Unlike conducting systems, where a scanning tunneling microscope\ncan be used to probe the electron distribution, there is no direct method for\nsolid-state-defect based qubits in wide-bandgap semiconductors. In this work,\nwe use pressure as a tuning method and a nuclear spin as an atomic scale probe\nto monitor the hyperfine structure of negatively charged nitrogen vacancy (NV)\ncenters in diamonds under pressure. We present a detailed study on the\nnearest-neighbor $^{13}C$ hyperfine splitting in the optically detected\nmagnetic resonance (ODMR) spectrum of NV centers at different pressures. By\nexamining the $^{13}C$ hyperfine interaction upon pressurizing, we show that\nthe NV hyperfine parameters have prominent changes, resulting in an increase in\nthe NV electron spin density and rehybridization from $sp^3$ to $sp^2$ bonds.\nThe $ab$ $initio$ calculations of strain dependence of the NV center's\nhyperfine levels are done independently. The theoretical results qualitatively\nagree well with experimental data without introducing any fitting parameters.\nFurthermore, this method can be adopted to probe the evolution of wavefunction\nin other defect systems. This potential capability could play an important role\nin developing magnetometry and quantum information processing using the defect\ncenters."
    },
    {
        "anchor": "Spin rotation, spin filtering, and spin transfer in directional\n  tunneling through non-centrosymmetric semiconductor barriers: We consider spin-dependent tunneling through a gallium arsenide barrier, a\nmaterial which has no inversion symmetry. We are dealing with free electrons,\nwith one effective mass and a spin-splitting in the barrier material. When we\ntake into account both the spin-orbit interaction and the absence of the\ninversion symmetry, the evanescent states in the barrier are spin split and the\ntunneling process can become rather involved. Along some crystallographic\ndirections, the incident wave experiences spin filtering during the tunneling.\nThese results open stimulating perspectives for spin manipulation in tunnel\ndevices.",
        "positive": "Density matrix renormalization group study of the charging of a quantum\n  dot strongly coupled to a single lead: A new application of the density matrix renormalization group (DMRG) method\nto a system composed of an interacting dot coupled to a infinite one\ndimensional lead is presented. This method enables one to study the influence\nof the coupling to an external lead on the thermodynamical properties of the\ndot. It is shown that this method reproduces known results for a\nnon-interacting dot coupled to a lead, i.e., that for strong coupling discrete\nstates remain in the dot. We show that these states are robust and do not\ndisappear once interactions in the dot are considered. Moreover, due to these\ndiscrete states, Coulomb blockade affects the charging of the dot even though\nits strongly coupled to a lead."
    },
    {
        "anchor": "Entangled microwaves as a resource for entangling spatially separate\n  solid-state qubits: superconducting qubits, NV centers and magnetic molecules: Quantum correlations present in a broadband two-line squeezed microwave state\ncan induce entanglement in a spatially separated bipartite system consisting of\neither two single qubits or two qubit ensembles. By using an appropriate master\nequation for a bipartite quantum system in contact with two separate but\nentangled baths, the generating entanglement process in spatially separated\nquantum systems is thoroughly characterized. Our results provide evidence that\nthis entanglement transfer by dissipation is feasible yielding to a\nsteady-state amount of entanglement in the bipartite quantum system which can\nbe optimized for a wide range of realistic physical systems that include\nstate-of-the-art experiments with NV centers in diamond, superconducting qubits\nor even magnetic molecules embedded in a crystalline matrix.",
        "positive": "Contribution of electron-phonon coupling to the luminescence spectra of\n  single colloidal quantum dots: Luminescence spectroscopy experiments were realized for single colloidal\nquantum dots CdSe/ZnS in a broad temperature range above room temperature in a\nnitrogen atmosphere. Broadening and shifts of spectra due to the temperature\nchange as well as due to spectral diffusion processes were detected and\nanalyzed. A linear correlation between the positions of maxima and the squared\nlinewidths of the spectra was found. This dependence was explained by a model\nwhich takes into account the slow variation of the electron-phonon coupling\nstrength."
    },
    {
        "anchor": "Long-Distance Superexchange between Semiconductor Quantum-Dot Electron\n  Spins: Because of their long coherence times and potential for scalability,\nsemiconductor quantum-dot spin qubits hold great promise for quantum\ninformation processing. However, maintaining high connectivity between\nquantum-dot spin qubits, which favor linear arrays with nearest neighbor\ncoupling, presents a challenge for large-scale quantum computing. In this work,\nwe present evidence for long-distance spin-chain-mediated superexchange\ncoupling between electron spin qubits in semiconductor quantum dots. We weakly\ncouple two electron spins to the ends of a two-site spin chain. Depending on\nthe spin state of the chain, we observe oscillations between the distant end\nspins. We resolve the dynamics of both the end spins and the chain itself, and\nour measurements agree with simulations. Superexchange is a promising technique\nto create long-distance coupling between quantum-dot spin qubits.",
        "positive": "Modular Groups, Visibility Diagram and Quantum Hall Effect: We consider the action of the modular group $\\Gamma (2)$ on the set of\npositive rational fractions. From this, we derive a model for a classification\nof fractional (as well as integer) Hall states which can be visualized on two\n``visibility\" diagrams, the first one being associated with even denominator\nfractions whereas the second one is linked to odd denominator fractions. We use\nthis model to predict, among some interesting physical quantities, the relative\nratios of the width of the different transversal resistivity plateaus. A\nnumerical simulation of the tranversal resistivity plot based on this last\nprediction fits well with the present experimental data."
    },
    {
        "anchor": "Kondo effect in a Aharonov-Casher interferometer: We consider a model describing a spin field-effect transistor based on a\nquantum nanowire with a tunable spin-orbit interaction embedded between two\nferromagnetic leads with anticollinear magnetization. We investigate a regime\nof a strong interplay between resonance Kondo scattering and interference\nassociated with the Aharonov-Casher effect. Using the Keldysh technique at weak\ncoupling regime we calculate perturbatively the charge current. It is predicted\nthat the effects of the spin-orbit interaction result in a non-vanishing\ncurrent for any spin polarization of the leads including the case of fully\npolarized anti-collinear contacts. We analyze the influence of the\nAharonov-Casher phase and degree of spin polarization in the leads onto a Kondo\ntemperature.",
        "positive": "Harmonic Content of Strain-induced Potential Modulation in\n  Unidirectional Lateral Superlattices: Detailed analysis of the commensurability oscillation (CO) has been performed\non unidirectional lateral superlattices with periods ranging from a=92 to 184\nnm. Fourier analysis reveals the second (and the third) harmonics along with\nthe fundamental oscillation for a>=138 nm (184 nm) at low-enough temperature,\nevincing the presence of corresponding harmonics in the profile of the\npotential modulation. The harmonics manifest themselves in CO with demagnified\namplitude due to the low-pass filtering action of the thermal damping factor;\nwith a suitable consideration of the damping effect, the harmonics of the\nmodulation potential are found to have the amplitudes V_2 and V_3 up to roughly\n30% of that of the fundamental component V_1, despite the small ratio of the\nperiod a to the depth d = 99 nm of the two-dimensional electron gas (2DEG) from\nthe surface. The dependence of V_n on a indicates that the fundamental\ncomponent originates at the surface, while the higher harmonics arise from the\neffect of the strain that penetrates down into subsurface. The manipulation of\nhigh harmonics thus provides a useful technique to introduce small length-scale\nmodulation into high-mobility 2DEGs located deep inside the wafer."
    },
    {
        "anchor": "Velocity-modulation control of electron-wave propagation in graphene: Wave propagation control by spatial modulation of velocity has a long history\nin optics and acoustics. We address velocity-modulation control of electron\nwave propagation in graphene and other two-dimensional Dirac-electron systems,\npointing out a key distinction of the Dirac-wave case. We also propose a\nstrategy for pattern transfer from a remote metallic layer that is based on\nmany-body velocity renormalization.",
        "positive": "Threes Company: Enabled by recent advances in symmetry and electronic structure, researchers\nhave observed signatures of unconventional threefold degeneracies in tungsten\ncarbide, challenging a longstanding paradigm in nodal semimetals."
    },
    {
        "anchor": "Electron and nuclear spin properties of the nanohole-filled GaAs/AlGaAs\n  quantum dots: GaAs/AlGaAs quantum dots grown by in-situ droplet etching and nanohole\ninfilling offer a combination of strong charge confinement, optical efficiency,\nand spatial symmetry required for polarization entanglement and spin-photon\ninterface. Here we study spin properties of such dots. We find nearly vanishing\nelectron $g$-factor ($g_e<0.05$), providing a route for electrically driven\nspin control schemes. Optical manipulation of the nuclear spin environment is\ndemonstrated with nuclear spin polarization up to $60\\%$ achieved. NMR\nspectroscopy reveals the structure of two types of quantum dots and yields the\nsmall magnitude of residual strain $\\epsilon_b<0.02\\%$ which nevertheless leads\nto long nuclear spin lifetimes exceeding 1000 s. The stability of the nuclear\nspin environment is advantageous for applications in quantum information\nprocessing.",
        "positive": "Terahertz emission from multiple-microcavity exciton-polariton lasers: Terahertz emission between exciton-polariton branches in semiconductor\nmicrocavities is expected to be strongly stimulated in the polariton laser\nregime, due to the high density of particles in the lower state (final state\nstimulation effect). However, non-radiative scattering processes depopulate the\nupper state and greatly hinder the efficiency of such terahertz sources. In\nthis work, we suggest a new scheme using multiple microcavities and exploiting\nthe transition between two interband polariton branches located below the\nexciton level. We compare the non-radiative processes loss rates in single and\ndouble cavity devices and we show that a dramatic reduction can be achieved in\nthe latter, enhancing the efficiency of the terahertz emission."
    },
    {
        "anchor": "Compact silicon double and triple dots realized with only two gates: We report electronic transport on silicon double and triple dots created with\nthe optimized number of two gates. Using silicon nitride spacers two dots in\nseries are created below two top gates overlapping a silicon nanowire. Coupling\nbetween dots is controlled by gate voltages. A third dot is created either by\ncombined action of gate voltages or local doping depending on the spacers\nlength. The main characteristics of the triple dot stability diagram are\nquantitatively fitted.",
        "positive": "Strong Quantization of Current-carrying Electron States in\n  $\u03b4$-layer Systems: We present an open-system quantum-mechanical real-space study of the\nconductive properties and size quantization in phosphorus $\\delta$-layers\nsystems, interesting for their beyond-Moore and quantum computing applications.\nRecently it has been demonstrated that an open-system quantum mechanical\ntreatment provides a much more accurate match to ARPES measurements in\nhighly-conductive, highly-confined systems than the traditional approaches\n(i.e. periodic or Dirichlet boundary conditions) and, furthermore, it allows\naccurate predictions of conductive properties of such systems from the first\nprinciples. Here we reveal that quantization effects are strong for device\nwidths $W<10$~nm, and we show, for the first time, that the number of\npropagating modes determines not only the conductivity, but the distinctive\nspatial distribution of the current-carrying electron states. For $W>10$~nm,\nthe quantization effects practically vanish and the conductivity tends to the\ninfinitely-wide device's values."
    },
    {
        "anchor": "Indirect magnetic signals mediated by a single surface band in Weyl\n  semimetals: Recently, abundant transport phenomena characterizing the surface states of\nWeyl semimetals (WSMs) have been reported. To generate these phenomena,\nelectrons have to complete a closed intersurface orbit. Due to the unavoidable\nimpurities in real materials, this orbit would be destroyed by the impurity\nscattering, which limits the detection of the surface states in WSMs. Here, we\ninvestigate the RKKY interaction between magnetic impurities, solely mediated\nby a single surface band, in semi-infinite WSMs. It is found that peculiar\noscillations and slowly decaying laws of the RKKY interaction can act as the\nsignals to capture the dispersive nature of the surface states of WSMs. The\nunderlying physics is attributed to two effects: the band-edge effect and the\nbending effect of the surface band, which can control the RKKY interaction\nindividually or compete with each other to produce more complex magnetic\nbehaviors. In addition, the band-edge effect together with the finite Fermi\nenergy would result in another interesting oscillation with battering pattern.\nAll the results are significantly different from that in previous literatures\nwhere surface states have to couple with bulk states (or other surface states\nof different spins) to generate nonzero magnetic interaction. Compared to the\nprevious models of surface states, the model here is more practical and is\nhelpful for the deeper understanding of the surface magnetic properties in\nWSMs.",
        "positive": "Spin transitions driven by electric dipole spin resonance in fluorinated\n  single- and bilayer-graphene quantum dots: Spin transitions driven by a periodically varying electric potential in\ndilute fluorinated graphene quantum dots are investigated. Flakes of monolayer\ngraphene are considered as well as electrostatic electron traps induced in\nbilayer graphene. The stationary states are obtained within the tight-binding\napproach and are used to the basis of eigenstates to describe the system\ndynamics. The dilute fluorination of the top layer lifts the valley degeneracy\nof the confined states and attenuates the orbital magnetic dipole moments due\nto current circulation within the flake. Moreover, the spin-orbit coupling\nintroduced by the surface deformation of the top layer induced by the adatoms\nallows spin flips to be driven by the AC electric field. For the bilayer\nquantum dots the spin flip times is substantially shorter than the experimental\nspin relaxation. Dynamical effects including many-photon and multilevel\ntransitions are also discussed."
    },
    {
        "anchor": "Interband resonant high-harmonic generation by valley polarized\n  electron-hole pairs: We demonstrated nonperturbative high harmonics induced by intense\nmid-infrared light up to 18th order that well exceed the material bandgap in\nmonolayer transition metal dichalcogenides. The intensities of the even-order\nhigh-harmonic radiation did not monotonically decrease as the harmonic order\nincreased. By comparing the high harmonic spectra with the optical absorption\nspectra, we found that the enhancement in the even-order high harmonics could\nbe attributed to the resonance to the band nesting energy. The symmetry\nanalysis shows that the valley polarization and anisotropic band structure lead\nto polarization of the high-harmonic radiation under excitation with the\npolarization along the zigzag direction. We also examined the possible\nrecombination pathways of electrons and holes by calculating their dynamics in\nreal and momentum spaces based on three-step model in solids. It revealed that,\nby considering the electrons and holes generated at neighboring lattice sites,\nthe electron-hole polarization driven to the band nesting region should\ncontribute to the high harmonic radiation. Our findings open the way for\nattosecond science with monolayer materials having widely tunable electronic\nstructures.",
        "positive": "Thermal conductivity of group-IV Semiconductors from a\n  Kinetic-Collective Model: The thermal conductivity of several diamond-like materials is calculated from\na kinetic-collective model. From this approach, a thermal conductivity\nexpression is obtained that includes a transition from a kinetic (free) to a\ncollective (hydrodynamic) behavior of the phonon field. The expression contains\nonly three parameters. Once fitted to natural occurring silicon, the same\nparameters for the other materials are directly calculated from theoretical\nrelations. The results are in good agreement with experimental data."
    },
    {
        "anchor": "Three-terminal interface as a thermoelectric generator beyond Seebeck\n  effect: We investigate thermoelectric transport through interfaces with inelastic\nscatterings by developing a quantum theory, which has been extensively\nvalidated by existing theories. We find that under temperature bias, while a\ntwo-terminal conductor-insulator interface behaves only as a thermal resistor,\na three-terminal conductor-insulator-conductor interface can function as an\nelectricity generator caused by phonon-mediated electron scatterings with\nheat-charge current separation. Unlike conventional thermoelectrics which is a\nproperty of a bulk caused by the Seebeck effect, this thermoelectric behavior\nis a property of an interface driven by electron-phonon scatterings.",
        "positive": "Gain Modulation by Graphene Plasmons in Aperiodic Lattice Lasers: Two-dimensional graphene plasmon-based technologies will enable the\ndevelopment of fast, compact and inexpensive active photonic elements because,\nunlike plasmons in other materials, graphene plasmons can be tuned via the\ndoping level. Such tuning is harnessed within terahertz quantum cascade lasers\nto reversibly alter their emission. This is achieved in two key steps: First by\nexciting graphene plasmons within an aperiodic lattice laser and, second, by\nengineering photon lifetimes, linking graphene's Fermi energy with the\nround-trip gain. Modal gain and hence laser spectra are highly sensitive to the\ndoping of an integrated, electrically controllable, graphene layer.\nDemonstration of the integrated graphene plasmon laser principle lays the\nfoundation for a new generation of active, programmable plasmonic metamaterials\nwith major implications across photonics, material sciences and nanotechnology."
    },
    {
        "anchor": "Comment on 'Design and circuit simulation of nanoscale vacuum channel\n  transistors' by J. Xu, Y. Qin, Y. Shi, Y. Yang and X. Zhang, Nanoscale Adv.\n  2020, 2, 3582: These comments aim to correct some apparent weaknesses in the theory of field\nelectron emission given in a recent paper about nanoscale vacuum channel\ntransistors, and to improve the presentation of this theory. In particular, it\nis argued that a \"simplified\" formula stated in the paper should not be used,\nbecause this formula is known to under-predict emission current densities by a\nlarge factor (typically around 300 for an emitting surface with local work\nfunction 4.5 eV). Thus, the \"simplified\" formula may significantly\nunder-predict the practical performance of a nanoscale vacuum channel\ntransistor.",
        "positive": "Multi-Valued Logic Gates based on Ballistic Transport in Quantum Point\n  Contacts: Multi-valued logic gates, which can handle quaternary numbers as inputs, are\ndeveloped by exploiting the ballistic transport properties of quantum point\ncontacts in series. The principle of a logic gate that finds the minimum of two\nquaternary number inputs is demonstrated. The device is scalable to allow\nmultiple inputs, which makes it possible to find the minimum of multiple inputs\nin a single gate operation. Also, the principle of a half-adder for quaternary\nnumber inputs is demonstrated. First, an adder that adds up two quaternary\nnumbers and outputs the sum of inputs is demonstrated. Second, a device to\nexpress the sum of the adder into two quaternary digits [Carry (first digit)\nand Sum (second digit)] is demonstrated. All the logic gates presented in this\npaper can in principle be extended to allow decimal number inputs with high\nquality QPCs."
    },
    {
        "anchor": "A new magnetic field dependence of Landau levels on a graphene like\n  structure: We consider a tight-binding model on the honeycomb lattice in a magnetic\nfield. For special values of the hopping integrals, the dispersion relation is\nlinear in one direction and quadratic in the other. We find that, in this case,\nthe energy of the Landau levels varies with the field B as E_n(B) ~\n[(n+\\gamma)B]^{2/3}. This result is obtained from the low-field study of the\ntight-binding spectrum on the honeycomb lattice in a magnetic field (Hofstadter\nspectrum) as well as from a calculation in the continuum approximation at low\nfield. The latter links the new spectrum to the one of a modified quartic\noscillator. The obtained value $\\gamma=1/2$ is found to result from the\ncancellation of a Berry phase.",
        "positive": "Quantum oscillations of the nonlinear planar effects signifying chiral\n  anomaly in Weyl Semimetals: In view of searching the signature of the celebrated chiral anomaly (CA) in\nWeyl semimetals (WSMs) in ongoing experiments, quantum oscillation in linear\nresponse regime has been considered as an important signature in the magneto\ntransports in WSMs, due to its unique relation to CA. Investigating the\nnonlinear planar effects (NPEs) starting from the semiclassical regime to the\nultra-quantum limit within the framework of Boltzmann transport theory\nincorporating Landau quantization, we here propose the quantum oscillations in\nNPEs can serve as a robust signature of CA in WSMs. By obtaining analytical\nexpressions, we show that the quantum oscillations of the nonlinear effects\nexhibit two different period scales in 1/B (B is the magnetic field) compared\nto the linear responses where only one period scale exists. We find that these\nquantum oscillations in NPEs are attributed to the deviation of chiral chemical\npotential (CCP), which is proportional to the finite band tilt as well as\ntransverse electric field and therefore, directly linked to CA in WSMs. In\naddition, we also show that the CA-induced nonlinear magneto conductivity is\nlinear and independent in the magnetic field in the semiclassical and\nultraquantum regimes, respectively. We conclude that the proposed behaviors of\nNPEs in different regimes uniquely signify the existence of CA and therefore,\ncan serve as a probe of identifying CA in WSMs in experiments."
    },
    {
        "anchor": "Excited State Quantum Couplings and Optical Switching of an Artificial\n  Molecule: We optically probe the spectrum of ground and excited state transitions of an\nindividual, electrically tunable self-assembled quantum dot molecule.\nPhotocurrent absorption measurements show that the spatially direct neutral\nexciton transitions in the upper and lower dots are energetically separated by\nonly ~2 meV. Excited state transitions ~8-16 meV to higher energy exhibit\npronounced anticrossings as the electric field is tuned due to the formation of\nhybridized electron states. We show that the observed excited state transitions\noccur between these hybridized electronic states and different hole states in\nthe upper dot. By simultaneously pumping two different excited states with two\nlaser fields we demonstrate a strong (88% on-off contrast) laser induced\nswitching of the optical response. The results represent an electrically\ntunable, discrete coupled quantum system with a conditional optical response.",
        "positive": "The magnetopolaron effect in light reflection and absorption by a wide\n  quantum: Light reflection and absorption spectra by a semiconductor quantum well (QW),\nwhich width is comparable to a light wave length of stimulating radiation, are\ncalculated. A resonance with two close located exited levels is considered.\nThese levels can arise due to splitting of an energy level of an electron-hole\npair (EHP) due to magnetopolaron effect, if the QW is in a quantizing magnetic\nfield directed perpendicularly to the QW plane. It is shown that unlike a case\nof narrow QWs light reflection and absorption depend on a QW width $d$. The\ntheory is applicable at any ratio of radiative and non-radiative broadenings of\nelectronic excitations."
    },
    {
        "anchor": "Optical microscope and tapered fiber coupling apparatus for a dilution\n  refrigerator: We have developed a system for tapered fiber measurements of optomechanical\nresonators inside a dilution refrigerator, which is compatible with both on-\nand off-chip devices. Our apparatus features full three-dimensional control of\nthe taper-resonator coupling conditions enabling critical coupling, with an\noverall fiber transmission efficiency of up to 70%. Notably, our design\nincorporates an optical microscope system consisting of a coherent bundle of\n37,000 optical fibers for real-time imaging of the experiment at a resolution\nof $\\sim$1 $\\mu$m. We present cryogenic optical and optomechanical measurements\nof resonators coupled to tapered fibers at temperatures as low as 9 mK.",
        "positive": "Anomalous shift and optical vorticity in the steady photovoltaic current: Steady illumination of a non-centrosymmetric semiconductor results in a bulk\nphotovoltaic current, which is contributed by real-space displacements\n(`shifts') of charged quasiparticles as they transit between Bloch states. The\nshift induced by interband excitation via absorption of photons has received\nthe prevailing attention. However, this excitation-induced shift can be far\noutweighed ($\\ll$) by the shift induced by intraband relaxation, or by the\nshift induced by radiative recombination of electron-hole pairs. This\noutweighing ($\\ll$) is attributed to (i) time-reversal-symmetric, intraband\nBerry curvature, which results in an anomalous shift of quasiparticles as they\nscatter with phonons, as well as to (ii) topological singularities in the\ninterband Berry phase (`optical vortices'), which makes the photovoltaic\ncurrent extraordinarily sensitive to the linear polarization vector of the\nlight source. Both (i-ii) potentially lead to nonlinear conductivities of order\n$mAV^{-2}$, without finetuning of the incident radiation frequency, band gap,\nor joint density of states."
    },
    {
        "anchor": "Band Structure for Thermal Conduction in Multilayered Systems. Thermal\n  Crystals: In this paper we solve the Cattaneo-Vernotte Equation for a periodic\nheterostructure made of alternate layers of different materials. The solutions\ndescribe thermal waves traveling in a periodic system, and it allows us to\nintroduce the concept of thermal crystals. We show that the dispersion relation\nshows the characteristics of a band-structure, however the corresponding Bloch\nwave vector is always complex corresponding to pseudo-bands, unlike what\nhappens in photonic or acoustic crystals. In this context, we also discuss the\nuse of the Floquet-Bloch theorem for thermal waves. The case of finite layered\nstructures is also analyzed showing the possibility of changing the temperature\nand heat flux by introducing defects opening the possibility of thermal\nmanagement through the pseudo-band structure.",
        "positive": "Out-of-plane heat transfer in van der Waals stacks: electron-hyperbolic\n  phonon coupling: Van der Waals heterostructures have emerged as promising building blocks that\noffer access to new physics, novel device functionalities, and superior\nelectrical and optoelectronic properties. Applications such as thermal\nmanagement, photodetection, light emission, data communication, high-speed\nelectronics and light harvesting require a thorough understanding of\n(nanoscale) heat flow. Here, using time-resolved photocurrent measurements we\nidentify an efficient out-of-plane energy transfer channel, where charge\ncarriers in graphene couple to hyperbolic phonon polaritons in the\nencapsulating layered material. This hyperbolic cooling is particularly\nefficient, giving picosecond cooling times, for hexagonal BN, where the\nhigh-momentum hyperbolic phonon polaritons enable efficient near-field energy\ntransfer. We study this heat transfer mechanism through distinct control knobs\nto vary carrier density and lattice temperature, and find excellent agreement\nwith theory without any adjustable parameters. These insights may lead to the\nability to control heat flow in van der Waals heterostructures."
    },
    {
        "anchor": "Tuning up the performance of GaAs-based solar cells by inelastic\n  scattering on quantum dots and doping of AlyGa1-ySb type-II dots and\n  AlxGa1-xAs spacers between dots: We used AlGaSb/AlGaAs material system for a theoretical study of photovoltaic\nperformance of the proposed GaAs-based solar cell in which the type-II quantum\ndot (QDs) absorber is spatially separated from the depletion region. Due to\ninelastic scattering of photoelectrons on QDs and proper doping of both QDs and\ntheir spacers, concentrated sunlight is predicted to quench recombination\nthrough QDs. Our calculation shows that 500-sun concentration can increase the\nShockley-Queisser limit from 35% to 40% for GaAs single-junction solar cells.",
        "positive": "Sinusoidally-Modulated Graphene Leaky-Wave Antenna for Electronic\n  Beamscanning at THz: This paper proposes the concept, analysis and design of a\nsinusoidally-modulated graphene leaky-wave antenna with beam scanning\ncapabilities at a fixed frequency. The antenna operates at terahertz\nfrequencies and is composed of a graphene sheet transferred onto a\nback-metallized substrate and a set of polysilicon DC gating pads located\nbeneath it. In order to create a leaky-mode, the graphene surface reactance is\nsinusoidally-modulated via graphene's field effect by applying adequate DC bias\nvoltages to the different gating pads. The pointing angle and leakage rate can\nbe dynamically controlled by adjusting the applied voltages, providing\nversatile beamscanning capabilities. The proposed concept and achieved\nperformance, computed using realistic material parameters, are extremely\npromising for beamscanning at THz frequencies, and could pave the way to\ngraphene-based reconfigurable transceivers and sensors."
    },
    {
        "anchor": "Kondo physics from quasiparticle poisoning in Majorana devices: We present a theoretical analysis of quasiparticle poisoning in\nCoulomb-blockaded Majorana fermion systems tunnel-coupled to normal-conducting\nleads. Taking into account finite-energy quasiparticles, we derive the\neffective low-energy theory and present a renormalization group analysis. We\nfind qualitatively new effects when a quasiparticle state with very low energy\nis localized near a tunnel contact. For $M=2$ attached leads, such \"dangerous\"\nquasiparticle poisoning processes cause a spin $S=1/2$ single-channel Kondo\neffect, which can be detected through a characteristic zero-bias anomaly\nconductance peak in all Coulomb blockade valleys. For more than two attached\nleads, the topological Kondo effect of the unpoisoned system becomes unstable.\nA strong-coupling bosonization analysis indicates that at low energy the\npoisoned lead is effectively decoupled and hence, for $M>3$, the topological\nKondo fixed point re-emerges, though now it involves only $M-1$ leads. As a\nconsequence, for $M=3$, the low-energy fixed point becomes trivial\ncorresponding to decoupled leads.",
        "positive": "Correlations between Majorana fermions through a superconductor: We consider a model of ballistic quasi-one dimensional semiconducting wire\nwith intrinsic spin-orbit interaction placed on the surface of a bulk s-wave\nsuperconductor (SC), in the presence of an external magnetic field. This setup\nhas been shown to give rise to a topological superconducting state in the wire,\ncharacterized by a pair of Majorana-fermion (MF) bound states formed at the two\nends of the wire. Here we demonstrate that, besides the well-known direct\noverlap-induced energy splitting, the two MF bound states may hybridize via\nelastic correlated tunneling processes through virtual quasiparticles states in\nthe SC, giving rise to an additional energy splitting between MF states from\nthe same as well as from different wires."
    },
    {
        "anchor": "Mechanism of parametric pumping of magnetization precession in a\n  nanomagnet. Parametric mechanism of current-induced magnetization reversal: A mechanism of current-induced magnetization reversal based on the parametric\nresonance is described. The source of the magnetization reversal is a\ncurrent-induced magnetic field, which is applied perpendicularly to the easy\naxis of magnetic anisotropy of a ferromagnetic nanomagnet. The current-induced\nmagnetic field was measured in a FeCoB nanomagnet to be 60 Gauss at a current\ndensity of 65 mA/um2. Two mechanisms of the magnetization reversal are\ndescribed and calculated. The first mechanism is the reversal by a RF\nelectrical current, which modulated at a frequency close to the precession\nfrequency of the nanomagnet. The second mechanism is the reversal by a DC\nelectrical current, in which the magneto-resistance and the current dependency\nof the induced magnetic field create a positive feedback loop, which amplifies\na random tiny thermal fluctuation into a large magnetization precession leading\nto the magnetization reversal. The combination of the proposed mechanism with\nconventional magnetization-reversal mechanisms such as the Spin Torque and the\nSpin-Orbit Torque can improve the performance of a Magnetic Random Access\nMemory.",
        "positive": "Surface Theory of a Family of Topological Kondo Insulators: A low-energy theory for the helical metallic states, residing on the surface\nof cubic topological Kondo insulators, is derived. Despite our analysis being\nprimarily focused on a prototype topological Kondo insulator, Samarium\nhexaboride (SmB$_6$), the surface theory derived here can also capture key\nproperties of other heavy fermion topological compounds with a similar\nunderlying crystal structure. Starting from an effective mean-field eight-band\nmodel in the bulk, we arrive at a low-energy description of the surface states,\npursuing both analytical and numerical approaches. In particular, we show that\nhelical Dirac excitations occur near the $\\bar{\\Gamma}$ point and the two\n$\\bar{X}$-points of the surface Brillouin zone and generally the energies of\nthe Dirac points display {\\it offset} relative to each other. We calculate the\ndependence of several observables (such as bulk insulating gap, energies of the\nsurface Dirac fermions, their relative position to the bulk gap, etc.) on\nvarious parameters in the theory. We also investigate the effect of a spatial\nmodulation of the chemical potential on the surface spectrum and show that this\nband bending generally results in \"dragging down\" of the Dirac points deep into\nthe valence band and strong enhancement of Fermi velocity of surface electrons.\nComparisons with recent ARPES and quantum oscillation experiments are drawn."
    },
    {
        "anchor": "Wess-Zumino-Berry phase interference in spin tunneling at excited levels\n  with a magnetic field: Macroscopic quantum coherence and spin-phase interference are studied between\nexcited levels in single-domain ferromagnetic particles in a magnetic field\nalong the hard anisotropy axis. The system has the general structure of\nmagnetocrystalline anisotropy, such as biaxial, trigonal, tetragonal, and\nhexagonal symmetry. This study not only just yields the previous spin-phase\ninterference results for the ground state tunneling, but also provide a\ngeneralization of the Kramers degeneracy to coherently spin tunneling at\nlow-lying excited states. These analytical results are found to be in good\nagreement with the numerical diagonalization. We also discuss the transition\nfrom quantum to classical behavior and the possible relevance to experiment.",
        "positive": "Breather mode in the many-electron dynamics of semiconductor quantum\n  wells: We demonstrate the existence of a novel breather mode in the self-consistent\nelectron dynamics of a semiconductor quantum well. A non-perturbative\nvariational method based on quantum hydrodynamics is used to determine the\nsalient features of the electron breather mode. Numerical simulations of the\ntime-dependent Wigner-Poisson or Hartree equations are shown to be in excellent\nagreement with our analytical results. For asymmetric quantum wells, a\nsignature of the breather mode is observed in the dipole response, which can be\ndetected by standard optical means."
    },
    {
        "anchor": "Gate-defined electron interferometer in bilayer graphene: We present an electron interferometer defined purely by electrostatic gating\nin encapsulated bilayer graphene. This minimizes possible sample degradation\nintroduced by conventional etching methods when preparing quantum devices. The\ndevice quality is demonstrated by observing Aharonov-Bohm (AB) oscillations\nwith a period of h/e, h/2e, h/3e, and h/4e, witnessing a coherence length of\nmany microns. The AB oscillations as well as the type of carriers (electrons or\nholes) are seamlessly tunable with gating. The coherence length longer than the\nring perimeter and semiclassical trajectory of the carrier are established from\nthe analysis of the temperature and magnetic field dependence of the\noscillations. Our gate-defined ring geometry has the potential to evolve into a\nplatform for exploring correlated quantum states such as superconductivity in\ninterferometers in twisted bilayer graphene.",
        "positive": "Spin wave localization and guiding by magnon band structure engineering\n  in yttrium iron garnet: In spintronics the propagation of spin-wave excitations in magnetically\nordered materials can also be used to transport and process information. One of\nthe most popular materials in this regard is the ferrimagnetic insulator\nyttrium-iron-garnet due its exceptionally small spin-wave damping parameter.\nWhile the small relaxation rate allows for large propagation length of magnetic\nexcitations, it also leads to non-locality of the magnetic properties. By\nimaging spin waves their band structure is mapped. In doing so wave vector\nselection is shown to suppress dispersion effects to a large extent allowing\nfor local measurements of spin relaxation. Moreover we demonstrate even higher\ncontrol of magnon propagation by employing the wave vector selectivity near an\navoided crossing of different spin-wave modes where the group velocity\napproaches zero. Here local engineering of the dispersion allows constructing\nmagnonic waveguides and at the same time reveals the local relaxation\nproperties."
    },
    {
        "anchor": "Effects of anisotropy and Coulomb interactions on quantum transport in a\n  quadruple quantum-dot structure: We present analytical and numerical investigation of spectral and transport\nproperties of a quadruple quantum-dot (QQD) structure which is one of the\npopular low-dimensional systems in the context of fundamental quantum physics\nstudy, future electronic applications and quantum calculations. The density of\nstates, occupation numbers and conductance of the structure were analyzed using\nthe nonequilibrium Green's functions in the tight binding approach and the\nequation-of-motion method. In particular the anisotropy of hopping integrals\nand on-site electron energies as well as the effects of the finite intra- and\ninterdot Coulomb interactions were investigated. It was found out that the\nanisotropy of the kinetic processes in the system leads to the Fano-Feshbach\nasymmetrical peak. We demonstrated that the conductance of QQD device has a\nwide insulating band with steep edges separating triple-peak structures if the\nintradot Coulomb interactions are taken into account. The interdot Coulomb\ncorrelations between the central QDs result in the broadening of this band and\nthe occurrence of an additional band with low conductance due to the Fano\nantiresonances. It was shown that in this case the conductance of the\nanisotropic QQD device can be dramatically changed by tuning the anisotropy of\non-site electron energies.",
        "positive": "Relaxation of quantum dots in a magnetic field at finite bias -- charge,\n  spin and heat currents: We perform a detailed study of the effect of finite bias and magnetic field\non the tunneling-induced decay of the state of a quantum dot by applying a\nrecently discovered general duality [PRB 93, 81411 (2016)]. This duality\nprovides deep physical insight into the decay dynamics of electronic open\nquantum systems with strong Coulomb interaction. It associates the amplitudes\nof decay eigenmodes of the actual system to the eigenmodes of a so-called dual\nsystem with attractive interaction. Thereby, it predicts many surprising\nfeatures in the transient transport and its dependence on experimental control\nparameters: the attractive interaction of the dual model shows up as sharp\nfeatures in the amplitudes of measurable time-dependent currents through the\nactual repulsive system. In particular, for interacting quantum dots, the\ntime-dependent heat current exhibits a decay mode that dissipates the\ninteraction energy and that is tied to the fermion parity of the system. We\nshow that its decay amplitude has an unexpected gate-voltage dependence that is\nrobust up to sizable bias voltages and then bifurcates, reflecting that the\nCoulomb blockade is lifted in the dual system. Furthermore, combining our\nduality relation with the known Iche-duality, we derive new symmetry properties\nof the decay rates as a function of magnetic field and gate voltage. Finally,\nwe quantify charge- and spin-mode mixing due to the magnetic field using a\nsingle mixing parameter."
    },
    {
        "anchor": "Non-local triple quantum dot thermometer based on Coulomb-coupled\n  systems: Recent proposals towards non-local thermoelectric voltage-based thermometry,\nin the conventional dual quantum dot set-up, demand an asymmetric step-like\nsystem-to-reservoir coupling around the ground states for optimal operation\n(Physica E, 114, 113635, 2019). In addition to such demand for unrealistic\ncoupling, the sensitivity in such a strategy also depends on the average\nmeasurement terminal temperature, which may result in erroneous temperature\nassessment. In this paper, I propose non-local current based thermometry in the\ndual dot set-up as a practical alternative and demonstrate that in the regime\nof high bias, the sensitivity remains robust against fluctuations of the\nmeasurement terminal temperature. Proceeding further, I propose a non-local\ntriple quantum dot thermometer, that provides an enhanced sensitivity while\nbypassing the demand for unrealistic step-like system-to-reservoir coupling and\nbeing robust against fabrication induced variability in Coulomb coupling. In\naddition, I show that the heat extracted from (to) the target reservoir, in the\ntriple dot design, can also be suppressed drastically by appropriate\nfabrication strategy, to prevent thermometry induced drift in reservoir\ntemperature. The proposed triple dot setup thus offers a multitude of benefits\nand could potentially pave the path towards the practical realization and\ndeployment of high-performance non-local ``sub-Kelvin range\" thermometers.",
        "positive": "In-situ electron-beam lithography of deterministic single-quantum-dot\n  mesa-structures using low-temperature cathodoluminescence spectroscopy: We report on the deterministic fabrication of sub-um mesa structures\ncontaining single quantum dots by in-situ electron-beam lithography. The\nfabrication method is based on a two-step lithography process using a\nlow-temperature cathodoluminescence (CL) spectroscopy setup. In the first step\nthe position and spectral features of single InGaAs quantum dots (QDs) are\ndetected by CL. Then circular sub-um mesa-structures are exactly defined by\nhigh-resolution electron-beam lithography and subsequent etching in the second\nstep. CL spectroscopy and micro-photoluminscence spectroscopy demonstrate the\nhigh optical quality of the single-QD mesa-structures with emission linewidths\nbelow 15 ueV and g(2)(0) = 0.04. Our lithography method allows for an alignment\nprecision better than 100 nm which paves the way for a fully-deterministic\ndevice technology using in-situ CL lithography."
    },
    {
        "anchor": "Phase diagram of the Quantum Electrodynamics of 2D and 3D Dirac\n  semimetals: We study the Quantum Electrodynamics of 2D and 3D Dirac semimetals by means\nof a self-consistent resolution of the Schwinger-Dyson equations, aiming to\nobtain the respective phase diagrams in terms of the relative strength of the\nCoulomb interaction and the number N of Dirac fermions. In this framework, 2D\nDirac semimetals have just a strong-coupling instability characterized by\nexciton condensation (and dynamical generation of mass) that we find at a\ncritical coupling well above previous theoretical estimates, thus explaining\nthe absence of that instability in free-standing graphene samples. On the other\nhand, we show that 3D Dirac semimetals have a richer phase diagram, with a\nstrong-coupling instability leading to dynamical mass generation up to N = 4\nand a line of critical points for larger values of N characterized by the\nvanishing of the electron quasiparticle weight in the low-energy limit. Such a\ncritical behavior signals the transition to a strongly correlated liquid,\ncharacterized by noninteger scaling dimensions that imply the absence of a pole\nin the electron propagator and are the signature of non-Fermi liquid behavior\nwith no stable electron quasiparticles.",
        "positive": "Valley-selective optical Stark effect in monolayer WS2: Breaking space-time symmetries in two-dimensional crystals (2D) can\ndramatically influence their macroscopic electronic properties. Monolayer\ntransition-metal dichalcogenides (TMDs) are prime examples where the\nintrinsically broken crystal inversion symmetry permits the generation of\nvalley-selective electron populations, even though the two valleys are\nenergetically degenerate, locked by time-reversal symmetry. Lifting the valley\ndegeneracy in these materials is of great interest because it would allow for\nvalley-specific band engineering and offer additional control in valleytronic\napplications. While applying a magnetic field should in principle accomplish\nthis task, experiments to date have observed no valley-selective energy level\nshifts in fields accessible in the laboratory. Here we show the first direct\nevidence of lifted valley degeneracy in the monolayer TMD WS2. By applying\nintense circularly polarized light, which breaks time-reversal symmetry, we\ndemonstrate that the exciton level in each valley can be selectively tuned by\nas much as 18 meV via the optical Stark effect. These results offer a novel way\nto control valley degree of freedom, and may provide a means to realize new\nvalley-selective Floquet topological phases in 2D TMDs."
    },
    {
        "anchor": "Non-reciprocal coherent dynamics of a single spin under closed-contour\n  interaction: Three-level quantum systems have formed a cornerstone of quantum optics since\nthe discovery of coherent population trapping (CPT) and electromagnetically\ninduced transparency. Key to these phenomena is quantum interference, which\narises if two of the three available transitions are coherently driven at\nwell-controlled amplitudes and phases. The additional coherent driving of the\nthird available transition would form a closed-contour interaction (CCI) from\nwhich fundamentally new phenomena would emerge, including phase-controlled CPT\nand one atom interferometry. However, due to the difficulty in experimentally\nrealising a fully coherent CCI, such aspects of three-level systems remain\nunexplored as of now. Here, we exploit recently developed methods for coherent\ndriving of single Nitrogen-Vacancy (NV) electronic spins to implement highly\ncoherent CCI driving. Our experiments reveal phase-controlled, single spin\nquantum interference fringes, reminiscent of electron dynamics on a triangular\nlattice, with the driving field phases playing the role of a synthetic magnetic\nflux. We find that for suitable values of this phase, CCI driving leads to\nefficient coherence protection of the NV spin, yielding a nearly two orders of\nmagnitude improvement of the coherence time, even for moderate drive strengths\n<~1MHz. Our results establish CCI driving as a novel paradigm in coherent\ncontrol of few-level systems that offers attractive perspectives for\napplications in quantum sensing or quantum information processing.",
        "positive": "Torsion induced effects in magnetic nanowires: Magnetic helix wire is one of the most simple magnetic systems which manifest\nproperties of both curvature and torsion. There exist two equilibrium states in\nthe helix wire with easy-tangential anisotropy: a quasi-tangential\nmagnetization distribution in case of relatively small curvatures and torsions,\nand an onion state in opposite case. In the last case the magnetization is\nclose to tangential one, deviations are caused by the torsion and curvature.\nPossible equilibrium magnetization states in the helix magnet with different\nanisotropy directions are studied theoretically. The torsion also essentially\ninfluences the spin-wave dynamics, acting as an effective magnetic field.\nOriginated from the curvature induced effective Dzyaloshinskii interaction,\nthis magnetic field leads to the coupling between the helix chirality and the\nmagnetochirality, it breaks mirror symmetry in spin-wave spectrum. All\nanalytical predictions on magnetization statics an dynamics are well confirmed\nby the direct spin lattice simulations."
    },
    {
        "anchor": "Functionalized AFM probes for force spectroscopy: eigenmodes shape and\n  stiffness calibration through thermal noise measurements: The functionalization of an Atomic Force Microscope (AFM) cantilever with a\ncolloidal bead is a widely used technique when the geometry between the probe\nand the sample must be controlled, particularly in force spectroscopy. But some\nquestions remain: how does a bead glued at the end of a cantilever influence\nits mechanical response ? And more important for quantitative measurements, can\nwe still determine the stiffness of the AFM probe with traditional techniques?\nIn this article, the influence of a colloidal mass loading on the eigenmodes\nshape and resonant frequency is investigated by measuring the thermal noise on\nrectangular AFM microcantilevers with and without a bead attached at their\nextremities. The experiments are performed with a home-made ultra-sensitive\nAFM, based on differential interferometry. The focused beam from the\ninterferometer probes the cantilever at different positions and the spatial\nshapes of the modes are determined up to the fifth resonance, without external\nexcitation. The results clearly demonstrate that the first eigenmode almost\ndoesn't change by mass loading. However the oscillation behavior of higher\nresonances present a marked difference: with a particle glued at its extremity,\nthe nodes of the mode are displaced towards the free end of the cantilever.\nThese results are compared to an analytical model taking into account the mass\nand the inertial moment of the load in an Euler-Bernoulli framework, where the\nnormalization of the eigenmodes is explicitly worked out in order to allow a\nquantitative prediction of the thermal noise amplitude of each mode. A good\nagreement between the experimental results and the analytical model is\ndemonstrated, allowing a clean calibration of the probe stiffness.",
        "positive": "Unveiling the charge distribution of a GaAs-based nanoelectronic device:\n  A large experimental data-set approach: In quantum nanoelectronics, numerical simulations have become an ubiquitous\ntool. Yet the comparison with experiments is often done at a qualitative level\nor restricted to a single device with a handful of fitting parameters. In this\nwork, we assess the predictive power of these simulations by comparing the\nresults of a single model with a large experimental data set of 110 devices\nwith 48 different geometries. The devices are quantum point contacts of various\nshapes and sizes made with electrostatic gates deposited on top of a high\nmobility GaAs/GaAlAs two dimensional electron gas. We study the pinch-off\nvoltages applied on the gates to deplete the two-dimensional electron gas in\nvarious spatial positions. We argue that the pinch-off voltages are a very\nrobust signature of the charge distribution in the device. The large\nexperimental data set allows us to critically review the modeling and arrive at\na robust one-parameter model that can be calibrated in situ, a crucial step for\nmaking predictive simulations."
    },
    {
        "anchor": "Spin Precession and Time-Reversal Symmetry Breaking in Quantum Transport\n  of Electrons Through Mesoscopic Rings: We consider the motion of electrons through a mesoscopic ring in the presence\nof spin-orbit interaction, Zeeman coupling, and magnetic flux. The coupling\nbetween the spin and the orbital degrees of freedom results in the geometric\nand the dynamical phases associated with a cyclic evolution of spin state.\nUsing a non-adiabatic Aharonov-Anandan phase approach, we obtain the exact\nsolution of the system and identify the geometric and the dynamical phases for\nthe energy eigenstates. Spin precession of electrons encircling the ring can\nlead to various interference phenomena such as oscillating persistent current\nand conductance. We investigate the transport properties of the ring connected\nto current leads to explore the roles of the time-reversal symmetry and its\nbreaking therein with the spin degree of freedom being fully taken into\naccount. We derive an exact expression for the transmission probability through\nthe ring. We point out that the time-reversal symmetry breaking due to Zeeman\ncoupling can totally invalidate the picture that spin precession results in\neffective, spin-dependent Aharonov-Bohm flux for interfering electrons.\nActually, such a picture is only valid in the Aharonov-Casher effect induced by\nspin-orbit interaction only. Unfortunately, this point has not been realized in\nprior works on the transmission probability in the presence of both SO\ninteraction and Zeeman coupling. We carry out numerical computation to\nillustrate the joint effects of spin-orbit interaction, Zeeman coupling and\nmagnetic flux. By examining the resonant tunneling of electrons in the weak\ncoupling limit, we establish a connection between the observable time-reversal\nsymmetry breaking effects manifested by the persistent current and by the\ntransmission probability. For a ring formed by two-dimensional electron gas, we",
        "positive": "Experimental observation of ABCB stacked tetralayer graphene: In tetralayer graphene, three inequivalent layer stackings should exist,\nhowever, only rhombohedral (ABCA) and Bernal (ABAB) stacking have so far been\nobserved. The three stacking sequences differ in their electronic structure,\nwith the elusive third stacking (ABCB) being unique as it is predicted to\nexhibit an intrinsic bandgap as well as locally flat bands around the K points.\nHere, we use scattering-type scanning near-field optical microscopy and\nconfocal Raman microscopy to identify and characterize domains of ABCB stacked\ntetralayer graphene. We differentiate between the three stacking sequences by\naddressing characteristic interband contributions in the optical conductivity\nbetween 0.28 and 0.56 eV with amplitude and phase-resolved near-field\nnano-spectroscopy. By normalizing adjacent flakes to each other, we achieve\ngood agreement between theory and experiment, allowing for the unambiguous\nassignment of ABCB domains in tetralayer graphene. These results establish\nnear-field spectroscopy at the interband transitions as a semi-quantitative\ntool, enabling the recognition of ABCB domains in tetralyer graphene flakes and\ntherefore, providing a basis to study correlation physics of this exciting\nphase."
    },
    {
        "anchor": "Shape-induced magnetic anisotropy in dilute magnetic alloys: We extend the theory of the surface-induced magnetic anisotropy to mesoscopic\nsamples with arbitrary geometry. The shape-induced anisotropy of impurity spins\nin small brick-shaped grains of dilute magnetic alloys is studied in detail.\nThe surface-induced blocking of a magnetic-impurity spin is shown to be very\nsensitive to geometric parameters of a grain. This implies that the apparent\ndiscrepancy between the experimental data of different groups on the size\ndependence of the Kondo resistivity can result from different microstructure of\nthe used samples. In order to interpret recent experimental data on the\nanomalous Hall effect in thin polycrystalline Fe doped Au films, we analyse the\nmagnetisation of impurity spins as a function of the impurity position and of\nthe grain shape.",
        "positive": "Particles in non-Abelian gauge potentials - Landau problem and insertion\n  of non-Abelian flux: We study charged spin-1/2 particles in two dimensions, subject to a\nperpendicular non-Abelian magnetic field. Specializing to a choice of vector\npotential that is spatially constant but non-Abelian, we investigate the Landau\nlevel spectrum in planar and spherical geometry, paying particular attention to\nthe role of the total angular momentum J = L +S. After this we show that the\nadiabatic insertion of non-Abelian flux in a spin-polarized quantum Hall state\nleads to the formation of charged spin-textures, which in the simplest cases\ncan be identified with quantum Hall Skyrmions."
    },
    {
        "anchor": "Foldy-Wouthuysen transformation for gapped Dirac fermions in\n  two-dimensional semiconducting materials and valley excitons under external\n  fields: In this work, we provide a detailed derivation of Foldy-Wouthuysen (FW)\ntransformation for two-dimensional (2D) gapped Dirac fermions under external\nfields and apply the formalism to study valley excitons in 2D semiconducting\nmaterials. Similar to relativistic quantum few-body problem, the gapped Dirac\nequation can be transformed into a Schr\\\"{o}dinger equation with \"relativistic\"\ncorrection terms. In this 2D materials system, the correction terms can be\ninterpreted as the Berry-curvature effect. The Hamiltonian for a valley exciton\nin external fields can be written based on the FW transformed Dirac\nHamiltonian. Various valley-dependent effects on excitons, such as\nfine-structure splittings of exciton energy levels, valley-selected exciton\ntransitions, and exciton valley Zeeman effect are discussed within this\nframework.",
        "positive": "Tangled nonlinear driven chain reactions of all optical singularities: Dynamics of polarization optical singularities chain reactions in generic\nelliptically polarized speckle fields created in photorefractive crystal LiNbO3\nwas investigated in details Induced speckle field develops in the tens of\nminutes scale due to photorefractive 'optical damage effect' induced by\nincident beam of He-Ne laser. It was shown that polarization singularities\ndevelop through topological chain reactions of developing speckle fields driven\nby photorefractive nonlinearities induced by incident laser beam. All optical\nsingularities (C points, optical vortices, optical diabolos,) are defined by\ninstantaneous topological structure of the output wavefront and are tangled by\nsingular optics lows. Therefore, they have develop in tangled way by six\ntopological chain reactions driven by nonlinear processes in used nonlinear\nmedium (photorefractive LiNbO3:Fe in our case): C-points and optical diabolos\nfor right (left) polarized components domains with orthogonally left (right)\npolarized optical vortices underlying them. All elements of chain reactions\nconsist from loop and chain links when nucleated singularities annihilated\ndirectly or with alien singularities in 1:9 ratio. The topological reason of\nstatistics was established by low probability of far enough separation of born\nsingularities pair from existing neighbor singularities during loop\ntrajectories. Topology of developing speckle field was measured and analyzed by\ndynamic stokes polarimetry with few seconds' resolution. The hierarchy of\nsingularities govern scenario of tangled chain reactions was defined. The\nuseful space-time data about peculiarities of optical damage evolution were\nobtained from existence and parameters of 'islands of stability' in developing\nspeckle fields."
    },
    {
        "anchor": "Ultra-strong Adhesion of Graphene Membranes: As mechanical structures enter the nanoscale regime, the influence of van der\nWaals forces increases. Graphene is attractive for nanomechanical systems\nbecause its Young's modulus and strength are both intrinsically high, but the\nmechanical behavior of graphene is also strongly influenced by the van der\nWaals force. For example, this force clamps graphene samples to substrates, and\nalso holds together the individual graphene sheets in multilayer samples. Here\nwe use a pressurized blister test to directly measure the adhesion energy of\ngraphene sheets with a silicon oxide substrate. We find an adhesion energy of\n0.45 \\pm 0.02 J/m2 for monolayer graphene and 0.31 \\pm 0.03 J/m2 for samples\ncontaining 2-5 graphene sheets. These values are larger than the adhesion\nenergies measured in typical micromechanical structures and are comparable to\nsolid/liquid adhesion energies. We attribute this to the extreme flexibility of\ngraphene, which allows it to conform to the topography of even the smoothest\nsubstrates, thus making its interaction with the substrate more liquid-like\nthan solid-like.",
        "positive": "Hunting Down Magnetic Monopoles in 2D Topological Insulators: Contrary to the electric charge that generates the electric field, magnetic\ncharge (namely magnetic monopoles) does not exist in the elementary\nelectromagnetism. Consequently, magnetic flux lines only form loops and cannot\nhave a source or a sink in nature. It is thus extraordinary to find that\nmagnetic monopoles can be pictured conceptually in topological materials.\nSpecifically in the 2D topological insulators, the topological invariant\ncorresponds to the total flux of an effective magnetic field (the Berry\ncurvature) over the reciprocal space.It is thus tempting to wrap the 2D\nreciprocal space into a compact manifold--a torus, and imagine the total flux\nto originate from magnetic monopoles inside the torus with a quantized total\ncharge. However, such a physically appealing picture has not been realized\nquantitatively: other than their existence in a toy (actually misleading)\npicture, the properties of the magnetic monopoles remain unknown. Here, we will\naddress this long-standing problem by hunting down the magnetic monopoles in\nthe reciprocal $k$-space. We will show that a simple and physically useful\npicture will arrive upon analytically continuing the system to a third\nimaginary momentum space. We then illustrate the evolution of the magnetic\nmonopoles across the topological phase transition and use it to provide natural\nexplanations on: 1) discontinuous jump of integer topological invariants, 2)\nthe semi-metallic nature on the phase boundary, and 3) how a change of global\ntopology can be induced via a local change in reciprocal space."
    },
    {
        "anchor": "Creating arbitrary quantum vibrational states in a carbon nanotube: We theoretically study the creation of single- and multi-phonon Fock states\nand arbitrary superpositions of quantum phonon states in a nanomechanical\ncarbon nanotube (CNT) resonator. In our model, a doubly clamped CNT resonator\nis initialized in the ground state and a single electron is trapped in a\nquantum dot which is formed by a electric gate potential and brought into the\nmagnetic field of a micro-magnet. The preparation of arbitrary quantum phonon\nstates is based on the coupling between the mechanical motion of the CNT and\nthe electron spin which acts as a non-linearity. We assume that electrical\ndriving pulses with different frequencies are applied on the system. The\nquantum information is transferred from the spin qubit to the mechanical motion\nby the spin-phonon coupling and the electron spin qubit can be reset by the\nsingle-electron spin resonance. We describe Wigner tomography which can be\napplied at the end to obtain the phase information of the prepared phonon\nstates.",
        "positive": "Andreev-reflection spectroscopy with superconducting indium - a case\n  study: We have investigated Andreev reflection at interfaces between superconducting\nindium (T_c = 3.4 K) and several normal conducting non-magnetic metals\n(palladium, platinum, and silver) down to T = 0.1 K as well as zinc (T_c = 0.87\nK) in its normal state at T = 2.5 K. We analysed the point-contact spectra with\nthe modified one-dimensional BTK theory valid for ballistic transport. It\nincludes Dynes' quasi-particle lifetime as fitting parameter Gamma in addition\nto superconducting energy gap 2Delta and strength Z of the interface barrier.\nFor contact areas from less than 1 nm^2 to 10000 nm^2 the BTK Z-parameter was\nclose to 0.5, corresponding to transmission coefficients of about 80%,\nindependent of the normal metal. The Z-parameter varies by less than +/-0.1\naround its average value, indicating that the interfaces have a negligible\ndielectric tunneling barrier. Also Fermi surface mismatch does not account for\nthe observed Z. The extracted value Z approx 0.5 can be explained by assuming\nthat practically all of our point contacts are in the diffusive regime."
    },
    {
        "anchor": "III-V quantum light source and cavity-QED on Silicon: Non-classical light sources offer a myriad of possibilities in fundamental\nscience and applications including quantum cryptography and quantum\nlithography. Single photons can encode quantum information and multi-qubit\ngates in silica waveguide circuits have been used to demonstrate linear optical\nquantum computing. Scale-up requires miniaturisation of the waveguide circuit\nand multiple photon sources. Silicon photonics, driven by the incentive of\noptical interconnects, is a highly promising platform for the passive\ncomponents, but integrated light sources are limited by silicon's indirect\nband-gap. III-V semiconductor quantum-dots, on the other hand, are proven\nquantum emitters. Here we demonstrate single-photon emission from quantum-dots\ncoupled to photonic crystal nanocavities fabricated from III-V material grown\ndirectly on silicon substrates. The high quality of the III-V material and\nphotonic structures is emphasized by observation of the strong-coupling regime.\nThis work opens-up the advantages of silicon photonics to the integration and\nscale-up of solid-state quantum optical systems.",
        "positive": "Edge and bulk electron states in a quasi-one-dimensional metal in a\n  magnetic field: The semi-infinite Wannier-Stark ladder: We study edge and bulk open-orbit electron states in a quasi-one-dimensional\n(Q1D) metal subject to a magnetic field. For both types of the states, the\nenergy spectrum near the Fermi energy consists of two terms. One term has a\ncontinuous dependence on the momentum along the chains, whereas the other term\nis quantized discretely. The discrete energy spectrum is mathematically\nequivalent to the Wannier-Stark energy ladder of a semi-infinite 1D lattice in\nan effective electric field. We solve the latter problem analytically in the\nsemiclassical approximation and by numerical diagonalization. We show\nexplicitly that equilibrium electric currents vanish both at the edges and in\nthe bulk, so no orbital magnetization is expected in a Q1D metal in a magnetic\nfield."
    },
    {
        "anchor": "Towards Graphene Nanoribbon-based Electronics: The successful fabrication of single layer graphene has greatly stimulated\nthe progress of the research on graphene. In this article, focusing on the\nbasic electronic and transport properties of graphene nanoribbons (GNRs), we\nreview the recent progress of experimental fabrication of GNRs, and the\ntheoretical and experimental investigations of physical properties and device\napplications of GNRs. We also briefly discuss the research efforts on the spin\npolarization of GNRs in relation to the edge states.",
        "positive": "Using single quantum states as spin filters to study spin polarization\n  in ferromagnets: By measuring electron tunneling between a ferromagnet and individual energy\nlevels in an aluminum quantum dot, we show how spin-resolved quantum states can\nbe used as filters to determine spin-dependent tunneling rates. We also observe\nmagnetic-field-dependent shifts in the magnet's electrochemical potential\nrelative to the dot's energy levels. The shifts vary between samples and are\ngenerally smaller than expected from the magnet's spin-polarized density of\nstates. We suggest that they are affected by field-dependent charge\nredistribution at the magnetic interface."
    },
    {
        "anchor": "Dissipative prethermal discrete time crystal: An ergodic system subjected to an external periodic drive will be generically\nheated to infinite temperature. However, if the applied frequency is larger\nthan the typical energy scale of the local Hamiltonian, this heating stops\nduring a prethermal period that extends exponentially with the frequency.\nDuring this prethermal period, the system may manifest an emergent symmetry\nthat, if spontaneously broken, will produce sub-harmonic oscillation of the\ndiscrete time crystal (DTC). We study the role of dissipation on the survival\ntime of the prethermal DTC. On one hand, a bath coupling increases the\nprethermal period by slowing down the accumulation of errors that eventually\ndestroy prethermalization. On the other hand, the spontaneous symmetry breaking\nis destabilized by interaction with environment. The result of this competition\nis a non-monotonic variation, i.e. the survival time of the prethermal DTC\nfirst increases and then decreases as the environment coupling gets stronger.",
        "positive": "Current-induced nuclear-spin activation in a two-dimensional electron\n  gas: Electrically detected nuclear magnetic resonance was studied in detail in a\ntwo-dimensional electron gas as a function of current bias and temperature. We\nshow that applying a relatively modest dc-current bias, I_dc ~ 0.5 microAmps,\ncan induce a re-entrant and even enhanced nuclear spin signal compared with the\nsignal obtained under similar thermal equilibrium conditions at zero current\nbias. Our observations suggest that dynamic nuclear spin polarization by small\ncurrent flow is possible in a two-dimensional electron gas, allowing for easy\nmanipulation of the nuclear spin by simple switching of a dc current."
    },
    {
        "anchor": "Cavity-photon-switched coherent transient transport in a double quantum\n  waveguide: We study a cavity-photon-switched coherent electron transport in a symmetric\ndouble quantum waveguide. The waveguide system is weakly connected to two\nelectron reservoirs, but strongly coupled to a single quantized photon cavity\nmode. A coupling window is placed between the waveguides to allow for electron\ninterference or inter-waveguide transport. The transient electron transport in\nthe system is investigated using a quantum master equation. We present a\ncavity-photon tunable semiconductor quantum waveguide implementation of an\ninverter quantum gate in which the output of the waveguide system may be\nselected via the selection of an appropriate photon number, or 'photon\nfrequency' of the cavity. In addition, the importance of the photon\npolarization in the cavity that is either parallel or perpendicular to the\ndirection of electron propagation in the waveguide system is demonstrated.",
        "positive": "Spin diode based on a single-wall carbon nanotube: Electronic transport through a single-wall metallic carbon nanotube weakly\ncoupled to one ferromagnetic and one nonmagnetic lead is analyzed in the\nsequential tunneling limit. It is shown that both the spin and charge currents\nflowing through such systems are highly asymmetric with respect to the bias\nreversal. As a consequence, nanotubes coupled to one nonmagnetic and one\nferromagnetic lead can be effectively used as spin diodes whose functionality\ncan be additionally controlled by a gate voltage."
    },
    {
        "anchor": "Second harmonic spectroscopy to optically detect valley polarization in\n  2D materials: Valley polarization (VP), an induced imbalance in the populations of a\nmulti-valley electronic system, allows emission of second harmonic (SH) light\neven in centrosymmetric crystals such as graphene. Whereas in systems such as\nMoS$\\mathrm{_2}$ or BN this adds to their intrinsic quadratic response, SH\ngeneration in a multi-valley inversion-symmetric crystal can provide a direct\nmeasure of valley polarization. By computing the nonlinear response and\ncharacterizing theoretically the respective SH as a function of polarization,\ntemperature, electron density, and degree of VP, we demonstrate the possibility\nof disentangling and individually quantifying the intrinsic and valley\ncontributions to the SH. A specific experimental setup is proposed to obtain\ndirect quantitative information about the degree of VP and allow its remote\nmapping. This approach could prove useful for direct, contactless, real-space\nmonitoring of valley injection and other applications of valley transport and\nvalleytronics.",
        "positive": "Destruction of the Kondo effect by a local measurement: We show that the local spin measurement which decoheres the localized spin in\na Kondo system, suppresses the Abrikosov-Suhl resonance and destroys the Kondo\neffect. This happens due to elimination of the entanglement between the\nlocalized spin and the conduction electrons, and differs essentially from\nsmearing of the resonance by dissipation. Considering decoherence by a spin\nbath, we predict that the Kondo effect disappears when the Kondo temperature\nbecomes smaller than the coupling with a bath. This effect can be detected in\nexperiments on ``quantum corrals'' or quantum dots doped by impurities with\ninternal degrees of freedom."
    },
    {
        "anchor": "Transmission of topological surface states through surface barriers: Topological surface states are a class of novel electronic states that are of\npotential interest in quantum computing or spintronic applications. Unlike\nconventional two-dimensional electron states, these surface states are expected\nto be immune to localization and to overcome barriers caused by material\nimperfection. Previous experiments have demonstrated that topological surface\nstates do not backscatter between equal and opposite momentum states, owing to\ntheir chiral spin texture. However, so far there is no evidence that these\nstates in fact transmit through naturally occurring surface defects. Here we\nuse a scanning tunnelling microscope to measure the transmission and reflection\nprobabilities of topological surface states of antimony through naturally\noccurring crystalline steps separating atomic terraces. In contrast to\nnontopological surface states of common metals (copper, silver and gold), which\nare either reflected or absorbed by atomic steps, we show that topological\nsurface states of antimony penetrate such barriers with high probability. This\ndemonstration of the extended nature of antimony's topological surface states\nsuggests that such states may be useful for high current transmission even in\nthe presence of atomic scale irregularities-an electronic feature sought to\nefficiently interconnect nanoscale devices.",
        "positive": "Characteristic singular behaviors of nodal line materials emerging in\n  orbital magnetic susceptibility and Hall conductivity: The bulk properties of nodal line materials have been an important research\ntopic in recent years. In this paper, we study the orbital magnetic\nsusceptibility and the Hall conductivity of nodal line materials using the\nformalism with thermal Green's functions and find characteristic singular\nbehaviors of them. It is shown that, in the vicinity of the gapless nodal line,\nthe orbital magnetic susceptibility shows a $\\delta$-function singularity and\nthe Hall conductivity shows a step function behavior in their chemical\npotential dependences. Furthermore, these singular behaviors are found to show\nstrong field angle dependences corresponding to the orientation of the nodal\nline in the momentum space. These singular behaviors and strong angle\ndependences will give clear evidence for the presence of the nodal line and its\norientation and can be used to experimentally detect nodal line materials."
    },
    {
        "anchor": "Chirality polarizations and spectral bulk-boundary correspondence: Surface physics dominated by bulk properties has been one of the central\ninterests in modern condensed matter physics, from electric polarization to\nbulk-boundary correspondence of topological insulators and superconductors.\nHere, we extend theory of electric polarization to chirality polarizations,\nthat is, surface charges corresponding to local antisymmetries characterized as\na bulk property. Using the notion of chirality polarizations, we prove the\nrecently proposed spectral bulk-boundary correspondence, a generalization of\nbulk-boundary correspondence in chiral symmetric systems into complex\nfrequencies. We show a physically transparent proof via Wannier functions and a\nformal proof by considering the change of surface chirality charges,\nhighlighting the similarities and the differences between electric polarization\nand chirality polarizations.",
        "positive": "Harnessing the giant out-of-plane Rashba effect and the nanoscale\n  persistent spin helix via ferroelectricity in SnTe thin films: A non-vanishing electric field inside a non-centrosymmetric bulk crystal\ntransforms into a momentum- dependent magnetic field, namely, a spin-orbit\nfield (SOF). SOFs are of great use in spintronics because they enable spin\nmanipulation via the electric field. At the same time, however, spintronic\napplications are severely limited by the SOF, as electrons traversing the SOF\neasily lose their spin information. Here, we propose that in-plane\nferroelectricity in (001)-oriented SnTe thin films harness the Janus-faced SOF\nin a reconcilable way to enable electrical spin controllability and suppress\nspin dephasing. The in-plane ferroelectricity produces a unidirectional\nout-of-plane Rashba SOF that can host a long-lived helical spin mode known as a\npersistent spin helix (PSH). Through direct coupling between the inversion\nasymmetry and the SOF, the ferroelectric switching reverses the out-of-plane\nRashba SOF, giving rise to a maximally field-tunable PSH. Furthermore, the\ngiant out- of-plane Rashba SOF seen in the SnTe thin films is linked to the\nnano-sized PSH, potentially reducing spintronic device sizes to the nanoscale.\nWe combine the two ferroelectric-coupled degrees of freedom, longitudinal\ncharge and transverse PSH, to design intersectional electro-spintronic\ntransistors governed by non-volatile ferroelectric switching within nanoscale\nlateral and atomic-thick vertical dimensions."
    },
    {
        "anchor": "Generalized Fowler-Nordheim field-induced vertical electron emission\n  model for two-dimensional materials: Current theoretical description of field-induced electron emission remains\nmostly bounded by the classic Fowler-Nordheim (FN) framework developed nearly\none century ago. For the emerging class of two-dimensional (2D) materials, many\nbasic assumptions of FN model become invalid due to their reduced\ndimensionality and exotic electronic properties. In this work, we develop\nanalytical and semi-analytical models of field-induced vertical electron\nemission from the surface of 2D materials by explicitly taking into account the\nreduced dimensionality, non-parabolic energy spectrum, non-conserving in-plane\nelectron momentum, finite-temperature and space-charge-limited effects. We show\nthat the traditional FN law is no longer valid for 2D materials. The modified\nvertical field emission model developed here provides better agreement with\nexperimental results. Intriguingly, a new high-field regime of \\emph{saturated\nsurface field emission} emerges due to the reduced dimensionality of 2D\nmaterials. A remarkable consequence of this saturated field emission effect is\nthe absence of space-charge-limited current normally expected at high field in\nthree-dimensional bulk material.",
        "positive": "Polaritonic Feshbach Resonance: A Feshbach resonance occurs when the energy of two interacting free particles\ncomes to resonance with a molecular bound state. When approaching this\nresonance, dramatic changes in the interaction strength between the particles\noccur. Feshbach resonances have been an essential tool to control the atom\ninteractions, which can even be switched from repulsive to attractive [1-4].\nThanks to Feshbach resonances many effects in ultracold atomic gases could be\nexplored [5, 6]. Here we demonstrate a Feshbach resonance based on polariton\nspinor interactions that characterize the fundamental interaction process in\npolariton quantum systems. We show the clear enhancement of attractive\ninteractions and the prompt change to repulsive interaction by tuning the\nenergy of two polaritons with anti-parallel spins across the biexciton bound\nstate energy. A mean field two-channel model quantitatively reproduces the\nexperimental results. This observation paves the way for a new tool to tune the\npolariton interactions and to move forward into quantum correlated polariton\nphysics."
    },
    {
        "anchor": "Dissipation-driven generation of two-qubit entanglement mediated by\n  plasmonic waveguides: We study the generation of entanglement between two distant qubits mediated\nby the surface plasmons of a metallic waveguide. We show that a V-shaped\nchannel milled in a flat metallic surface is much more efficient for this\npurpose than a metallic cylinder. The role of the misalignments of the dipole\nmoments of the qubits, an aspect of great importance for experimental\nimplementations, is also studied. A careful analysis of the quantum-dynamics of\nthe system by means of a master equation shows that two-qubit entanglement\ngeneration is essentially due to the dissipative part of the effective\nqubit-qubit coupling provided by the surface plasmons. The influence of a\ncoherent external pumping, needed to achieve a steady state entanglement, is\ndiscussed. Finally, we pay attention to the question of how to get information\nexperimentally on the degree of entanglement achieved in the system.",
        "positive": "Polaritonic network as a paradigm for dynamics of coupled oscillators: Photonic and polaritonic lattices have been recently theoretically proposed\nand experimentally realised as many-body simulators due to the rich behaviors\nexhibited by such systems at the macroscale. We show that the networks of\npolariton condensates encapsulate a large variety of behaviours of systems of\ncoupled oscillators. By eliminating spatial degrees of freedom in nonresonantly\npumped polariton network, we establish that depending on the values of\nexperimentally tunable parameters the networks of polariton condensates may\nrepresent Kuramoto, Sakaguchi-Kuramoto, Stuart-Landau, Lang-Kobayashi\noscillators and beyond. The networks of polariton condensates are therefore\ncapable of implementing various regimes acting as analogue spin Hamiltonian\nminimizers, producing complete and cluster synchronization, exotic spin glasses\nand large scale secondary synchronization of oscillations. We suggest that the\nrecently implemented control of the system parameters for individual sites in\npolariton lattices allows addressing for the first time the interaction of\nsublattices that belong to different oscillatory classes."
    },
    {
        "anchor": "Green's function representation of spin pumping effect: In this study, current pumping by an external potential is studied on the\nbasis of the Keldysh Green's function method, and a pumping formula written in\nterms of retarded and advanced Green's functions is obtained. It is shown that\npumping is essentially driven by a change of particle distribution before and\nafter an external perturbation. The formula is used to study the spin pumping\neffect in the case of strong sd exchange interaction, and the driving field is\nidentified to be the spin gauge field. At the lowest order in the precession\nfrequency of magnetization, the spin gauge field works as a constant potential,\nand the system is shown to reduce to a static problem of spin current\ngeneration by a time-independent potential with off-diagonal spin components.",
        "positive": "Mesoscopic fluctuations of spin currents: Spin currents may be generated by applying bias voltages V to the\nnanostructures even in the absence of spin-active ferromagnetic interfaces.\nMost theoretical proposals concentrate on a concrete spin-orbit interaction and\non the disorder-averaged effect. It remains underappreciated that any\nspin-orbit interaction produces random spin currents with a typical amplitude\ne^2 V/\\hbar not affected by disorder. This work addresses such mesoscopic\nfluctuations of spin currents for generic model of a nanostructure where\nseveral quantum connectors meet in a single node. The analysis is performed in\nthe framework of recently developed quantum circuit theory of G_Q corrections\nand reveals four distinct mechanisms of spin current fluctuations. The results\nare elaborated for simple models of tunnel and ballistic connectors."
    },
    {
        "anchor": "Theoretical treatment of anharmonicity of vibrational modes of\n  single-walled carbon nanotubes: We report a computational study, using the \"moments method\" [Y. Gao and M.\nDaw, Modelling Simul. Mater. Sci. Eng. 23 045002 (2015)], of the anharmonicity\nof the vibrational modes of single-walled carbon nanotubes. We find that modes\nwith displacements largely within the wall are more anharmonic than modes with\ndominantly radial character, except for a set of modes that are related to the\nradial breathing mode which are the most anharmonic of all. We also find that\nperiodicity of the calculation along the tube length does not strongly affect\nthe anharmonicity of the modes, but that the tubes with larger diameter show\nmore anharmonicity. Comparison is made with available experiments and other\ncalculations.",
        "positive": "Spin Injection and Inverse Edelstein Effect in the Surface States of\n  Topological Kondo Insulator SmB6: There has been considerable interest in exploiting the spin degrees of\nfreedom of electrons for potential information storage and computing\ntechnologies. Topological insulators (TI), a class of quantum materials, have\nspecial gapless edge/surface states, where the spin polarization of the Dirac\nfermions is locked to the momentum direction. This spin-momentum locking\nproperty gives rise to very interesting spin-dependent physical phenomena such\nas the Edelstein and inverse Edelstein effects. However, the spin injection in\npure surface states of TI is very challenging because of the coexistence of the\nhighly conducting bulk states. Here, we experimentally demonstrate the spin\ninjection and observe the inverse Edelstein effect in the surface states of a\ntopological Kondo insulator, SmB6. At low temperatures when only surface\ncarriers are present, a clear spin signal is observed. Furthermore, the\nmagnetic field angle dependence of the spin signal is consistent with\nspin-momentum locking property of surface states of SmB6."
    },
    {
        "anchor": "Full-counting statistics of information content and heat quantity in the\n  steady state and the optimum capacity: We consider a bipartite quantum conductor and analyze fluctuations of heat\nquantity in a subsystem as well as self-information associated with the\nreduced-density matrix of the subsystem. By exploiting the multi-contour\nKeldysh technique, we calculate the R\\'enyi entropy, or the information\ngenerating function, subjected to the constraint of the local heat quantity of\nthe subsystem, from which the probability distribution of conditional\nself-information is derived. We present an equality that relates the optimum\ncapacity of information transmission and the R\\'enyi entropy of order 0, which\nis the number of integer partitions into distinct parts. We apply our formalism\nto a two-terminal quantum dot. We point out that in the steady state, the\nreduced-density matrix and the operator of the local heat quantity of the\nsubsystem may be commutative.",
        "positive": "Resonant Nonlinear Damping of Quantized Spin Waves in Ferromagnetic\n  Nanowires: We use spin torque ferromagnetic resonance to measure the spectral properties\nof dipole-exchange spin waves in permalloy nanowires. Our measurements reveal\nthat geometric confinement has a profound effect on the damping of spin waves\nin the nanowire geometry. The damping parameter of the lowest-energy quantized\nspin wave mode depends on applied magnetic field in a resonant way and exhibits\na maximum at a field that increases with decreasing nanowire width. This\nenhancement of damping originates from a nonlinear resonant three-magnon\nconfluence process allowed at a particular bias field value determined by\nquantization of the spin wave spectrum in the nanowire geometry."
    },
    {
        "anchor": "Trapping of Cold Excitons with Laser Light: Optical trapping and manipulation of neutral particles has led to a variety\nof experiments from stretching DNA-molecules to trapping and cooling of neutral\natoms. An exciting recent outgrowth of the technique is an experimental\nimplementation of atom Bose-Einstein condensation. In this paper, we propose\nand demonstrate laser induced trapping for a new system--a gas of excitons in\nquantum well structures. We report on the trapping of a highly degenerate Bose\ngas of excitons in laser induced traps.",
        "positive": "Topological Micro-Electro-Mechanical Systems: We explore the topological aspect of dynamics in a micro-electro-mechanical\nsystem (MEMS), which is a combination of an electric-circuit system and a\nmass-spring system. A simplest example is a sequential chain of capacitors and\nsprings. It is shown that such a chain exhibits novel topological dynamics with\nrespect to its oscillation modes. On one hand, when it undergoes free\noscillation, the system is governed by the Su-Schrieffer-Heeger model, and the\ntopological charge is given by a winding number. Topological and trivial phases\nare differentiated by measuring the dynamics of the outermost plate. On the\nother hand, when it undergoes periodical motion in time, the system is governed\nby an inversion-symmetric-trimer model, and the topological phases are\ncharacterized by an inversion-symmetry indicator. There emerge topological edge\nstates, which are well signaled by measuring electromechanical-impedance\nresonance. Our results will open an attractive field of topological MEMS."
    },
    {
        "anchor": "Current noise through a Kondo quantum dot in a SU(N) Fermi liquid state: The current noise through a mesoscopic quantum dot is calculated and analyzed\nin the Fermi liquid regime of the SU(N) Kondo model. Results connect the\nJohnson-Nyquist noise to the shot noise for an arbitrary ratio of voltage and\ntemperature, and show that temperature corrections are sizeable in usual\nexperiments. For the experimentally relevant SU(4) case, quasiparticle\ninteractions are shown to increase the shot noise.",
        "positive": "Weak anti-localization in spin-orbit coupled lattice systems: The quantum correction to electrical conductivity is studied on the basis of\ntwo-dimensional Wolff Hamiltonian, which is an effective model for a spin-orbit\ncoupled (SOC) lattice system. It is shown that weak anti-localization (WAL)\narises in SOC lattices, although its mechanism and properties are different\nfrom the conventional WAL in normal metals with SOC impurities. The interband\nSOC effect induces the contribution from the interband singlet Cooperon, which\nplays a crucial role for WAL in the SOC lattice. It is also shown that there is\na crossover from WAL to weak localization in SOC lattices when the Fermi energy\nor band gap changes. The implications of the present results to Bi-Sb alloys\nand PbTe under pressure are discussed."
    },
    {
        "anchor": "Interfacial Dzyaloshinskii-Moriya interaction in Ta\\Co20Fe60B20\\MgO\n  nanowires: We report current-induced domain wall motion (CIDWM) in Ta\\Co20Fe60B20\\MgO\nnanowires. Domain walls are observed to move against the electron flow when no\nmagnetic field is applied, while a field along the nanowires strongly affects\nthe domain wall motion direction and velocity. A symmetric effect is observed\nfor up-down and down-up domain walls. This indicates the presence of\nright-handed domain walls, due to a Dzyaloshinskii-Moriya interaction (DMI)\nwith a DMI coefficient D=+0.06 mJ/m2. The positive DMI coefficient is\ninterpreted to be a consequence of boron diffusion into the tantalum buffer\nlayer during annealing. In a Pt\\Co68Fe22B10\\MgO nanowire CIDWM along the\nelectron flow was observed, corroborating this interpretation. The experimental\nresults are compared to 1D-model simulations including the effects of pinning.\nThis advanced modelling allows us to reproduce the experiment outcomes and\nreliably extract a spin-Hall angle {\\theta}SH=-0.11 for Ta in the nanowires,\nshowing the importance of an analysis that goes beyond the currently used model\nfor perfect nanowires.",
        "positive": "Equilibrium and Nonequilibrium Thermodynamics of a Photon Gas in the\n  Near Field: In this paper we study the near-field thermodynamics of a photon gas at\nequilibrium as well as out-of-equilibrium in the presence of dissipative\neffects. As a consequence of Heisenberg's uncertainty principle, we are able to\neliminate the low-frequency modes in both cases, providing an analytical\nexpression for the near-field entropy. In addition, we obtain the\nentropic-force contributions to the Casimir effect. At zero temperature the\nwell-known $l^{-4}$ behavior of the pressure is obtained. In the nonequilibrium\ncase, we compute the entropy production, showing that the excess of heat in\neach bodies must be dissipated into the respective thermal reservoirs."
    },
    {
        "anchor": "Four-Dimensional Quantum Hall Effect in a Two-Dimensional Quasicrystal: One-dimensional (1D) quasicrystals exhibit physical phenomena associated with\nthe 2D integer quantum Hall effect. Here, we transcend dimensions and show that\na previously inaccessible phase of matter --- the 4D integer quantum Hall\neffect --- can be incorporated in a 2D quasicrystal. Correspondingly, our 2D\nmodel has a quantized charge-pump accommodated by an elaborate edge phenomena\nwith protected level crossings. We propose experiments to observe these 4D\nphenomena, and generalize our results to a plethora of topologically equivalent\nquasicrystals. Thus, 2D quasicrystals may pave the way to the experimental\nstudy of 4D physics.",
        "positive": "Second harmonic generation at the edge of a two-dimensional electron gas: We show that driving a two-dimensional electron gas by an in-plane electric\nfield oscillating at the frequency $\\omega$ gives rise to an electric current\nat $2\\omega$ flowing near the edge of the system. This current has both\nparallel and perpendicular to the edge components, which emit electromagnetic\nwaves at $2\\omega$ with different polarizations. We develop a microscopic\ntheory of such an edge second harmonic generation and calculate the edge\ncurrent at $2\\omega$ in different regimes of electron transport and electric\nfield screening. We also show that at high frequencies the spatial profile of\nthe edge current contains oscillations caused by excitation of plasma waves."
    },
    {
        "anchor": "Ultrasensitive Displacement Noise Measurement of Carbon Nanotube\n  Mechanical Resonators: Mechanical resonators based on a single carbon nanotube are exceptional\nsensors of mass and force. The force sensitivity in these ultra-light\nresonators is often limited by the noise in the detection of the vibrations.\nHere, we report on an ultra-sensitive scheme based on a RLC resonator and a\nlow-temperature amplifier to detect nanotube vibrations. We also show a new\nfabrication process of electromechanical nanotube resonators to reduce the\nseparation between the suspended nanotube and the gate electrode down to $\\sim\n150$~nm. These advances in detection and fabrication allow us to reach\n$0.5~\\mathrm{pm}/\\sqrt{\\mathrm{Hz}}$ displacement sensitivity. Thermal\nvibrations cooled cryogenically at 300~mK are detected with a signal-to-noise\nratio as high as 17~dB. We demonstrate $4.3~\\mathrm{zN}/\\sqrt{\\mathrm{Hz}}$\nforce sensitivity, which is the best force sensitivity achieved thus far with a\nmechanical resonator. Our work is an important step towards imaging individual\nnuclear spins and studying the coupling between mechanical vibrations and\nelectrons in different quantum electron transport regimes.",
        "positive": "Biorthogonal topological charge pumping in non-Hermitian systems: We study charge pumping in generic non-Hermitian settings, and show that\nquantized charge pumping is only guaranteed under a biorthogonal formalism\ntherein, where the charge transport is evaluated using the left and right\neigenvectors of the non-Hermitian Hamiltonian. Specifically, for biorthogonal\ncharge pumping in generic one-dimensional non-Hermitian models, we demonstrate\nhow quantized transport is related to the Chern number in the parameter space.\nWhen the non-Hermitian model possesses the non-Hermitian skin effect, under\nwhich Bloch states in the bulk are deformed and localize toward boundaries, we\npropose a scenario where the pumped charge is related to the non-Bloch Chern\nnumber defined in the parameter space involving the generalized Brillouin zone.\nWe illustrate the validity of our analytic results using concrete examples,\nand, in the context of the biorthogonal charge pumping, discuss in detail a\nrecent experiment where quantized charge pumping was observed in a lossy\nenvironment."
    },
    {
        "anchor": "Band bending at the surface of Bi$_2$Se$_3$ studied from first\n  principles: The band bending (BB) effect on the surface of the second-generation\ntopological insulators implies a serious challenge to design transport devices.\nThe BB is triggered by the effective electric field generated by charged\nimpurities close to the surface and by the inhomogeneous charge distribution of\nthe occupied surface states. Our self-consistent calculations in the\nKorringa-Kohn-Rostoker framework showed that in contrast to the bulk bands, the\nspectrum of the surface states is not bent at the surface. In turn, it is\npossible to tune the energy level of the Dirac point via the deposited surface\ndopants. In addition, the electrostatic modifications induced by the charged\nimpurities on the surface induce long range oscillations in the charge density.\nFor dopants located beneath the surface, however, these oscillations become\nhighly suppressed. Our findings are in good agreement with recent experiments,\nhowever, our results indicate that the concentration of the surface doping\ncannot be estimated from the energy shift of the Dirac cone within the scope of\nthe effective continuous model for the protected surface states.",
        "positive": "Universal quantum transport and impurity band super metallicity in\n  self-similar graphene carpets: Fractals, a fascinating mathematical concept made popular in the eighties,\nremained for decades a beautiful scientific curiosity mainly. With the\ntremendous advances in nanofabrication techniques, such as nanolithography, it\nhas become possible to design self-similar materials with fine structures down\nto nanometer scale. Here, we investigate the effects of self similarity on\nquantum electronic transport in graphene Sierpinski carpets. We find that a gap\nopens up in the electron spectrum in the middle of which lies a flat band of\nzeros energy modes. Although these states have a zero velocity, a supermetallic\nphase is found at the neutrality point. For Fermi energy located in the\nvalence/conduction band and in the presence of a small inelastic scattering the\nsystem stays metallic and the transport is found strongly anisotropic."
    },
    {
        "anchor": "A Generalized Open Quantum System Approach for the Electron Paramagnetic\n  Resonance of Magnetic Atoms: A recent experimental breakthrough allowed to probe electronic parametric\nresonance of a single magnetic atom in an STM setup. The results present\nintriguing features, such as an asymmetric lineshape and unusually large ratio\nof the decoherence and decay rates, which defy standard approaches using the\nconventional Bloch equations. To address these issues we employ novel\ngeneralized Bloch equations, together with proper microscopic modeling of the\nmagnetic adatom, and show how all the experimental features can naturally be\naccounted for. The proposed approach may also be useful in treating any future\nsimilar experiments, as well as next generation hybrid quantum devices.",
        "positive": "Resistance Spikes at Transitions between Quantum Hall Ferromagnets: We report a new manifestation of first-order magnetic transitions in\ntwo-dimensional electron systems. This phenomenon occurs in aluminum arsenide\nquantum wells with sufficiently low carrier densities and appears as a set of\nhysteretic spikes in the resistance of a sample placed in crossed parallel and\nperpendicular magnetic fields, each spike occurring at the transition between\nstates with different partial magnetizations. Our experiments thus indicate\nthat the presence of magnetic domains at the transition starkly increases\ndissipation, an effect also suspected in other ferromagnetic materials.\nAnalysis of the positions of the transition spikes allows us to deduce the\nchange in exchange-correlation energy across the magnetic transition, which in\nturn will help improve our understanding of metallic ferromagnetism."
    },
    {
        "anchor": "Influence of Interface Traps and Electron-Hole Puddles on Quantum\n  Capacitance and Conductivity in Graphene Field-Effect Transistors: We study theoretically an influence of the near-interfacial insulator traps\nand electron-hole puddles on the small-signal capacitance and conductance\ncharacteristics of the gated graphene structures. Based on the self-consistent\nelectrostatic consideration and taking into account the interface trap\ncapacitance the explicit analytic expressions for charge carrier density and\nthe quantum capacitance as functions of the gate voltage were obtained. This\nallows to extract the interface trap capacitance and density of interface\nstates from the gate capacitance measurements. It has shown that\nself-consistent account of the interface trap capacitance enables to reconcile\ndiscrepancies in universal quantum capacitance vs the Fermi energy extracted\nfor different samples. The electron-hole puddles and the interface traps impact\non transfer I-V characteristics and conductivity has been investigated. It has\nbeen shown that variety of widths of resistivity peaks in various samples could\nbe explained by different interface trap capacitance values.",
        "positive": "High-susceptibility nanoparticles for micro-inductor core materials: According to the laws of magnetism, the shape of magnetically soft objects\nlimits the effective susceptibility. For example, spherical soft magnets cannot\ndisplay an effective susceptibility larger than 3. Although true for\nmacroscopic multi-domain magnetic materials, we show that magnetic\nnanoparticles in a single-domain state do not suffer from this limitation. This\nis a consequence of the particle moment being forced to saturation by the\npredominance of exchange forces, and only allowed to rotate coherently in\nresponse to thermal and/or applied fields. We apply statistical mechanics to\ndetermine the static and dynamic susceptibility of single-domain particles as a\nfunction of size, temperature and material parameters. Our calculations reveal\nthat spherical single-domain particles with large saturation magnetisation and\nsmall magneto-crystalline anisotropy, e.g. FeNi particles, can have very a\nlarge susceptibility of 200 or more. We further show that susceptibility and\nlosses can be tuned by particle easy axis alignment with the applied field in\ncase of uniaxial anisotropy, but not for particles with cubic anisotropy. Our\nmodel is validated experimentally by comparison with measurements on\nnanocomposites containing spherical 11$\\pm$3 nm $\\gamma$-Fe$_2$O$_3$ particles\nup to 45 vol% finely dispersed in a polymer matrix. In agreement with the\ncalculations for this specific material, the measured susceptibility of the\ncomposites is up to 17 ($\\gg$3) and depends linearly on the volume fraction of\nparticles. Based on these results, we predict that nanocomposites of 30 vol% of\nsuperparamagnetic FeNi particles in an insulating non-magnetic matrix can have\na sufficiently large susceptibility to be used as micro-inductor core materials\nin the MHz frequency range, while maintaining losses below state-of-the-art\nferrites."
    },
    {
        "anchor": "Superconductivity and quantum oscillations in crystalline Bi nanowires: While bulk bismuth (Bi) is a semimetal, we have found clear evidence of\nsuperconductivity in a crystalline 72 nm diameter Bi nanowire below 1.3 K. In a\nparallel magnetic field (H), the residual resistance of the nanowire below Tc\ndisplays periodic oscillations with H, and the period corresponds to the\nsuperconducting flux quantum. This result provides evidence that the\nsuperconductivity comes from the interface shell between Bi and the surface\noxide. In a perpendicular H, the resistance in the superconducting state shows\nShubnikov-de Haas (SdH) oscillations, a signature of a normal metal. These\nresults indicate a novel coexistence of Bosonic and Fermionic states in the\nsurface shell of nanowires.",
        "positive": "Quantum oscillations in field-induced correlated insulators of a moir\u00e9\n  superlattice: We report an observation of quantum oscillations (QOs) in the correlated\ninsulators with valley anisotropy of twisted double bilayer graphene (TDBG).\nThe anomalous QOs are best captured in the magneto resistivity oscillations of\nthe insulators at v = -2, with a period of 1/B and an oscillation amplitude as\nhigh as 150 k{\\Omega}. The QOs can survive up to ~10 K, and above 12 K, the\ninsulating behaviors are dominant. The QOs of the insulator are strongly D\ndependent: the carrier density extracted from the 1/B periodicity decreases\nalmost linearly with D from -0.7 to -1.1 V/nm, suggesting a reduced Fermi\nsurface; the effective mass from Lifshitz-Kosevich analysis depends nonlinearly\non D, reaching a minimal value of 0.1 me at D = ~ -1.0 V/nm. Similar\nobservations of QOs are also found at v = 2, as well as in other devices\nwithout graphite gate. We interpret the D sensitive QOs of the correlated\ninsulators in the picture of band inversion. By reconstructing an inverted band\nmodel with the measured effective mass and Fermi surface, the density of state\nat the gap, calculated from thermal broadened Landau levels, agrees\nqualitatively with the observed QOs in the insulators. While more theoretical\nunderstandings are needed in the future to fully account for the anomalous QOs\nin this moir\\'e system, our study suggests that TDBG is an excellent platform\nto discover exotic phases where correlation and topology are at play."
    },
    {
        "anchor": "Majorana wavefunction oscillations, fermion parity switches, and\n  disorder in Kitaev chains: We study the decay and oscillations of Majorana fermion wavefunctions and\nground state (GS) fermion parity in one-dimensional topological superconducting\nlattice systems. Using a Majorana transfer matrix method, we find that Majorana\nwavefunction properties are encoded in the associated Lyapunov exponent, which\nin turn is the sum of two independent components: a `superconducting component'\nwhich characterizes the gap induced decay, and the `normal component', which\ndetermines the oscillations and response to chemical potential configurations.\nThe topological phase transition separating phases with and without Majorana\nend modes is seen to be a cancellation of these two components. We show that\nMajorana wavefunction oscillations are completely determined by an underlying\nnon-superconducting tight-binding model and are solely responsible for GS\nfermion parity switches in finite-sized systems. These observations enable us\nto analytically chart out wavefunction oscillations, the resultant GS parity\nconfiguration as a function of parameter space in uniform wires, and special\nparity switch points where degenerate zero energy Majorana modes are restored\nin spite of finite size effects. For disordered wires, we find that band\noscillations are completely washed out leading to a second localization length\nfor the Majorana mode and the remnant oscillations are randomized as per\nAnderson localization physics in normal systems. Our transfer matrix method\nfurther allows us to i) reproduce known results on the scaling of mid-gap\nMajorana states and demonstrate the origin of its log-normal distribution, ii)\nidentify contrasting behavior of disorder-dependent GS parity switches for the\ncases of even versus odd number of lattice sites, and iii) chart out the GS\nparity configuration and associated parity switch points as a function of\ndisorder strength.",
        "positive": "Tunability of the Fractional Quantum Hall States in Buckled Dirac\n  Materials: We report on the fractional quantum Hall states of germanene and silicene\nwhere one expects a strong spin-orbit interaction. This interaction causes an\nenhancement of the electron-electron interaction strength in one of the Landau\nlevels corresponding to the valence band of the system. This enhancement\nmanifests itself as an increase of the fractional quantum Hall effect gaps\ncompared to that in graphene and is due to the spin-orbit induced coupling of\nthe Landau levels of the conduction and valence bands, which modifies the\ncorresponding wave functions and the interaction within a single level. Due to\nthe buckled structure, a perpendicular electric field lifts the valley\ndegeneracy and strongly modifies the interaction effects within a single Landau\nlevel: in one valley the perpendicular electric field enhances the interaction\nstrength in the conduction band Landau level, while in another valley, the\nelectric field strongly suppresses the interaction effects."
    },
    {
        "anchor": "Fractional quantization of the ballistic conductance in electron and\n  hole systems: In the present article we give a brief overview of the theories of the 0.7\nanomaly of the ballistic conductance. The special attantion is given to the\nconcept of a fractional quantization of the ballistic conductance arising from\nexchange interaction of the Heisenberg type between the carrier localized in\nthe region of the quantum point contact and freely propagating carriers in\nelectron and hole systems.\n  -----\n  Brotask\\\"ommtun skotlei{\\eth}ninnar \\'i einv\\'i{\\eth}um rafeinda og\nholukerfum\n  \\'I grein {\\th}essari ver{\\eth}ur sk\\\"ommtun skotlei{\\eth}ninnar \\'i\neinv\\'i{\\eth}um kerfum \\'utsk\\'yr{\\eth} og fari{\\eth} yfir n\\'yjustu og helstu\nfr{\\ae}{\\eth}il\\'ik\\\"on \\'a svi{\\eth}i \\LDQ 0,7 fr\\'aviksins \\RDQ og tengdra\nfyrirbrig{\\eth}a \\'i einv\\'i{\\eth}um rafeinda og holukerfum. Vi{\\eth} kynnum\nhugmynd okkar um a{\\eth} brotask\\\"ommtun skotlei{\\eth}ninnar lei{\\eth}i af\nHeisenberg skiptaverkun milli sta{\\eth}bundins rafbera \\'i\nskammtapunktsnertunni og frj\\'alsra lei{\\eth}nirafbera og s\\'ynum fram \\'a\na{\\eth} heg{\\eth}un lei{\\eth}ninnar er eigindlega \\'ol\\'ik milli rafeinda og\nholukerfa.",
        "positive": "Quantum incompressibility and Razumov Stroganov type conjectures: We establish a correspondence between polynomial representations of the\nTemperley and Lieb algebra and certain deformations of the Quantum Hall Effect\nwave functions. When the deformation parameter is a third root of unity, the\nrepresentation degenerates and the wave functions coincide with the domain wall\nboundary condition partition function appearing in the conjecture of A.V.\nRazumov and Y.G. Stroganov. In particular, this gives a proof of the\nidentification of the sum of the entries of a O(n) transfer matrix eigenvector\nand a six vertex-model partition function, alternative to that of P. Di\nFrancesco and P. Zinn-Justin."
    },
    {
        "anchor": "Theory of cavity-polariton self-trapping and optical strain in polymer\n  chains: We consider a semiconductor polymer chain coupled to a single electromagnetic\nmode in a cavity. The excitations of the chain have a mixed exciton-photon\ncharacter and are described as polaritons. Polaritons are coupled to the\nlattice by the deformation potential interaction and can propagate in the\nchain. We find that the presence of optical excitation in the polymer induces\nstrain on the lattice. We use a BCS variational wavefunction to calculate the\nchemical potential of the polaritons as a function of their density. We analyze\nfirst the case of a short chain with only two unit cells in order to check the\nvalidity of our variational approach. In the case of a long chain and for a\nstrong coupling with the lattice, the system undergoes a phase transition\ncorresponding to the self-trapping of polaritons. The role of the exciton\nspontaneous emission and cavity damping are discussed in the case of\nhomogeneous optical lattice strain.",
        "positive": "The Chern-Simons Fermi Liquid Description of Fractional Quantum Hall\n  States: The composite fermion picture has had a remarkable number of recent successes\nboth in the description of the fractional quantized Hall states and in the\ndescription on the even denominator Fermi liquid like states. In this review we\ngive an introductory account of the Chern-Simons fermion theory, focusing on\nthe description of the even denominator states as unusual Fermi liquids.\nContents include:\n  1. Introduction\n  2. Introduction to Chern-Simons Fermions\n  3. RPA\n  4. Landau Fermi Liquid Theory and MRPA\n  5. Magnetization and M2RPA\n  6. Perturbative Approaches and Trouble in the Infrared\n  7. Wavefunction Picture of Composite Fermions and Dipole Approach\n  8. Selected Experiments\n  9. Last Words"
    },
    {
        "anchor": "Observation of new plasmons in the fractional quantum Hall effect:\n  interplay of topological and nematic orders: Collective modes of exotic quantum fluids reveal underlying physical\nmechanisms responsible for emergent complex quantum ground states. We observe\nunexpected new collective modes in the fractional quantum Hall (FQH) regime:\nintra-Landau-level plasmons in the second Landau level measured by resonant\ninelastic light scattering. The plasmons herald rotational-symmetry-breaking\nphases in tilted magnetic fields and reveal long-range translational invariance\nin these phases. The fascinating dependence of plasmon features on filling\nfactor provide new insights on interplays between topological quantum Hall\norder and nematic electronic liquid crystal phases. A marked intensity minimum\nin the plasmon spectrum at Landau level filling factor v = 5/2 strongly\nsuggests that this paired state, which could support non-Abelian excitations,\noverwhelms competing nematic phases, unveiling the robustness of the 5/2\nsuperfluid state for small tilt angles. At v = 7/3, a sharp and strong plasmon\npeak that links to emerging macroscopic coherence supports the proposed model\nof a FQH nematic state at this filling factor.",
        "positive": "Supersymmetry dictated topology in periodic gauge fields and realization\n  in strained and twisted 2D materials: Supersymmetry (SUSY) of Hamiltonian dictates double degeneracy between a pair\nof superpartners (SPs) transformed by supercharge, except at zero energy where\nmodes remain unpaired in many cases. Here we explore a SUSY of complete\nisospectrum between SPs -- with paired zero modes -- realized by 2D electrons\nin zero-flux periodic gauge fields, which can describe twisted or periodically\nstrained 2D materials. We find their low-energy sector containing zero (or\nthreshold) modes must be topologically non-trivial, by proving that Chern\nnumbers of the two SPs have a finite difference dictated by the number of zero\nmodes and energy dispersion in their vicinity. In $30^\\circ$ twisted bilayer\n(double bilayer) transition metal dichalcogenides subject to periodic strain,\nwe find one SP is topologically trivial in its lowest miniband, while the twin\nSP of identical dispersion has a Chern number of $1$ ($2$), in stark contrast\nto time-reversal partners that have to be simultaneously trivial or nontrivial.\nFor systems whose physical Hamiltonian corresponds to the square root of a SUSY\nHamiltonian, such as twisted or strained bilayer graphene, we reveal that\ntopological properties of the two SUSY SPs are transferred respectively to the\nconduction and valence bands, including the contrasted topology in the\nlow-energy sector and identical topology in the high-energy sector. This offers\na unified perspective for understanding topological properties in many\nflat-band systems described by such square-root models."
    },
    {
        "anchor": "Graphene antidot lattice waveguides: We introduce graphene antidot lattice waveguides: nanostructured graphene\nwhere a region of pristine graphene is sandwiched between regions of graphene\nantidot lattices. The band gap in the surrounding antidot lattices enable\nlocalized states to emerge in the central waveguide region. We model the\nwaveguides via a position-dependent mass term in the Dirac approximation of\ngraphene, and arrive at analytical results for the dispersion relation and\nspinor eigenstates of the localized waveguide modes. To include atomistic\ndetails we also use a tight-binding model, which is in excellent agreement with\nthe analytical results. The waveguides resemble graphene nanoribbons, but\nwithout the particular properties of ribbons that emerge due to the details of\nthe edge. We show that electrons can be guided through kinks without additional\nresistance and that transport through the waveguides is robust against\nstructural disorder.",
        "positive": "High-Fidelity and Ultrafast Initialization of a Hole Spin Bound to a Te\n  Isoelectronic Center in ZnS: We demonstrate the optical initialization of a hole-spin qubit bound to an\nisoelectronic center (IC) formed by a pair of Te impurities in ZnSe, an\nimpurity/host system providing high optical homogeneity, large electric dipole\nmoments, and long coherence times. The initialization scheme is based on the\nspin-preserving tunneling of a resonantly excited donor-bound exciton to a\npositively charged Te IC, thus forming a positive trion. The radiative decay of\nthe trion within less than 50 ps leaves a heavy hole in a well-defined\npolarization-controlled spin state. The initialization fidelity exceeds 98:5 %\nfor an initialization time of less than 150 ps."
    },
    {
        "anchor": "Parallel pumping for magnon spintronics: Amplification and manipulation\n  of magnon spin currents on the micron-scale: Magnonics and magnon spintronics aim at the utilization of spin waves and\nmagnons, their quanta, for the construction of wave-based logic networks via\nthe generation of pure all-magnon spin currents and their interfacing with\nelectrical charge transport. The promise of efficient parallel data processing\nand low power consumption renders this field one of the most promising research\nareas in spintronics. In this context, the process of parallel parametric\namplification, i.e., the conversion of microwave photons into magnons at one\nhalf of the microwave frequency, has proven to be a versatile tool. Its\nbeneficial and unique properties, such as frequency and mode-selectivity, the\npossibility to excite spin waves in a wide wavevector range and the creation of\nphase-correlated wave pairs, render it one of the key methods of spin-wave\ngeneration and amplification.\n  The application of parallel parametric amplification to micro- and\nnanostructures is an important step towards the realization of magnonic\nnetworks. This is motivated not only by the fact that amplifiers are an\nimportant tool for the construction of any extended logic network but also by\nthe unique properties of parallel parametric amplification, such as a\nphase-dependent amplification. Recently, the successful application of parallel\nparametric amplification to metallic microstructures has been reported. It has\nbeen demonstrated that parametric amplification provides an excellent tool to\ngenerate and to amplify spin waves in these systems. In particular, the\namplification greatly benefits from the discreteness of the spin-wave spectra.\nThis opens up new, interesting routes of spin-wave amplification and\nmanipulation. In this Review, we give an overview over the recent developments\nand achievements in this field.",
        "positive": "Change of chirality at magic angles of twisted bilayer graphene: We derive a simple formula for the real-space chirality of twisted bilayer\ngraphene that can be related to the cross-product of its sheet currents. This\nquantity shows well-defined plateaus for the first remote band as function of\nthe gate voltage which are approximately quantized for commensurate twist\nangles. The zeroth plateau corresponds to the first magic angle where a sign\nchange occurs due to an emergent $C_6$-symmetry. Our observation offers a new\ndefinition of the magic angle based on a macroscopic observable which is\naccessible in typical transport experiments."
    },
    {
        "anchor": "Templated self-assembly of iron oxide nanoparticles: We report on self-assembled iron oxide nanoparticle films on silicon\nsubstrates. In addition to homogeneously assembled layers, we fabricated\npatterned trenches of 40-1000 nm width using electron beam lithography for the\ninvestigation of assisted self-assembly. The nanoparticles with a diameter of\n20 nm +/- 7% were synthesized by thermal decomposition of iron oleate complexes\nin trioctylamine in presence of oleic acid. Samples with different track widths\nand nanoparticle concentration were characterized by scanning electron\nmicroscopy and by superconducting quantum interference device magnetometry.",
        "positive": "Graphene Nanobubble: A New Optical Nonlinear Material: Graphene is a rising star in nonlinear optics due to its saturable absorption\nand giant Kerr nonlinearity, these properties are useful in digital optics\nbased on optical nonlinear devices. However, practical applications require\nlarge optical nonlinearities and these are inherently limited by the\ninteraction length of atomically thin graphene. Here, we demonstrate optical\nbistability in a Fabry Perot cavity containing monolayer and bilayer graphene\nwhich have been restructured to form nanobubbles. We find that graphene\nnanobubble can act as a new type of optical nonlinear media due to its vertical\nside wall as well as added curvature, which enable strong non linear dispersive\neffects leading to a large optically induced phase change. Unlike thermally\ninduced bistability, the all optical switching between two transmission states\nhappens within a time scale of tens of nanoseconds. Nanobubble based optical\ndevices with intrinsic optical nonlinearity help to overcome the optical path\nlength limitation of atomically thin two dimensional films and allow us to\nexplore the promise of using such elements as the building block of digital\nall-optical circuitry."
    },
    {
        "anchor": "Cryogenic Microwave Imaging of Metal-Insulator Transition in Doped\n  Silicon: We report the instrumentation and experimental results of a cryogenic\nscanning microwave impedance microscope. The microwave probe and the scanning\nstage are located inside the variable temperature insert of a helium cryostat.\nMicrowave signals in the distance modulation mode are used for monitoring the\ntip-sample distance and adjusting the phase of the two output channels. The\nability to spatially resolve the metal-insulator transition in a doped silicon\nsample is demonstrated. The data agree with a semi-quantitative finite-element\nsimulation. Effects of the thermal energy and electric fields on local charge\ncarriers can be seen in the images taken at different temperatures and DC\nbiases.",
        "positive": "Kondo-Enhanced Andreev Tunneling in InAs Nanowire Quantum Dots: We report measurements of the nonlinear conductance of InAs nanowire quantum\ndots coupled to superconducting leads. We observe a clear alternation between\nodd and even occupation of the dot, with sub-gap-peaks at $|V_{sd}|=\\Delta/e$\nmarkedly stronger(weaker) than the quasiparticle tunneling peaks at\n$|V_{sd}|=2\\Delta/e$ for odd(even) occupation. We attribute the enhanced\n$\\Delta$-peak to an interplay between Kondo-correlations and Andreev tunneling\nin dots with an odd number of spins, and substantiate this interpretation by a\npoor man's scaling analysis."
    },
    {
        "anchor": "Consequences of a possible adiabatic transition between \u03bd=1/3 and\n  \u03bd=1 quantum Hall states in a narrow wire: We consider the possibility of creating an adiabatic transition through a\nnarrow neck, or point contact, between two different quantized Hall states that\nhave the same number of edge modes, such as \\nu=1 and \\nu=1/3. We apply both\nthe composite fermion and the Luttinger liquid formalism to analyze the\ntransition. We suggest that using such adiabatic junctions one could build a DC\nstep-up transformer, where the output voltage is higher than the input.\nDifficulties standing in the way of an experimental implementation of the\nadiabatic junction are addressed.",
        "positive": "Role of time reversal symmetry and tilting in circular photogalvanic\n  responses: We study the role of time reversal symmetry (TRS) in the circular\nphotogalvanic (CPG) responses considering chiral Weyl semimetal (WSM) while a\nquantized CPG response is guaranteed by broken of both inversion symmetry (IS)\nand mirror symmetries. The TRS broken WSM yields one left and one right chiral\nWeyl nodes (WNs) while there are two left and right chiral WNs for TRS\ninvariant WSM. We show that these features can potentially cause the\nquantization of CPG response at higher values compared to the topological\ncharge of the underlying WSM. This is further supported by the fact that Berry\ncurvature and velocity behave differently whether the system preserves or\nbreaks the TRS. We find the CPG responses for TRS invariant type-II WSM to be\nquantized at two and four times the topological charge of the activated WNs\nwhile the chemical potential are respectively chosen in the vicinity of\nenergies associated with left and right chiral WNs. By contrast, irrespective\nof the above choice of the chemical potential, the quantization in CPG response\nis directly given by the topological charge of the activated WNs for TRS broken\ncase. Interestingly, we notice non-quantized peak in CPG response when energies\nof WNs associated with opposite chiralities are close to each other as it is\nthe case for TRS invariant type-I WSM considered here. Moreover, we show that\nthe tilt can significantly modify the CPG response as velocity in the tilt\ndirection changes which enters into the CPG tensor through the Fermi\ndistribution function. Given these exciting outcomes, the second order CPG\nresponse emerges as a useful indicator to characterize the system under\nconsideration. Furthermore, we investigate the momentum resolved structure of\nCPG response to relate with the final results and strengthen our analysis from\nthe perspective of the lattice models."
    },
    {
        "anchor": "Nonequilibrium transport properties of a double quantum dot in the Kondo\n  regime: We analyze the nonequilibrium transport properties of a parallel double\nquantum dot in terms of its full counting statistics (FCS). The parameters of\nthe setup are assumed to be such that both subsystems are driven into the Kondo\nregime. After a series of transformations the Hamiltonian is then mapped onto a\nMajorana resonant level model, which effectively describes the Toulouse point\nof the respective double impurity two-terminal Kondo model. Its FCS is then\nobtained at arbitrary constellation of voltage, temperature, and local magnetic\nfields. We identify two different transport processes corresponding to single\nelectron tunneling as well as an electron pair process and give the respective\neffective transport coefficients. In the most universal linear response regime\nthe FCS turns out to be of a binomial shape with an effective transmission\ncoefficient. Furthermore, we find a complete transport suppression\n(antiresonance) at a certain parameter constellation, which is similar to the\none found in the noninteracting quantum dots. By an explicit expansion around\nthe Toulouse point we show that the antiresonance is universal and should be\nobservable in the generic Kondo dot setup. We discuss experimental implications\nof our predictions as well as possible routes for generalizations of our\napproach.",
        "positive": "Plasmon-mediated Coulomb drag between graphene waveguides: We analyze theoretically charge transport in Coulomb coupled graphene\nwaveguides (GWGs). The GWGs are defined using antidot lattices, and the lateral\ngeometry bypasses many technological challenges of earlier designs. The drag\nresistivity $\\rho_D$, which is a measure of the many-particle interactions\nbetween the GWGs, is computed for a range of temperatures and waveguide\nseparations. It is demonstrated that for $T>0.1T_F$ the drag is significantly\nenhanced due to plasmons, and that in the low-temperature regime a complicated\nbehavior may occur. In the weak coupling regime the dependence of drag on the\ninterwaveguide separation $d$ follows $\\rho_D \\sim d^{-n}$, where $n \\simeq 6$."
    },
    {
        "anchor": "Kondo Physics and Exact Solvability of Double Dots Systems: We study two double dot systems, one with dots in parallel and one with dots\nin series, and argue they admit an exact solution via the Bethe ansatz. In the\ncase of parallel dots we exploit the exact solution to extract the behavior of\nthe linear response conductance. The linear response conductance of the\nparallel dot system possesses multiple Kondo effects, including a Kondo effect\nenhanced by a nonpertubative antiferromagnetic RKKY interaction, has\nconductance zeros in the mixed valence regime, and obeys a non-trivial form of\nthe Friedel sum rule.",
        "positive": "The Zeeman, Spin-Orbit, and Quantum Spin-Hall Interactions in\n  Anisotropic and Low-Dimensional Conductors: When an electron or hole is in a conduction band of a crystal, it can be very\ndifferent from 2, depending upon the crystalline anisotropy and the direction\nof the applied magnetic induction ${\\bf B}$. In fact, it can even be 0! To\ndemonstrate this quantitatively, the Dirac equation is extended for a\nrelativistic electron or hole in an orthorhombically-anisotropic conduction\nband with effective masses $m_j$ for $j=1,2,3$ with geometric mean\n$m_g=(m_1m_2m_3)^{1/3}$. The appropriate Foldy-Wouthuysen transformations are\nextended to evaluate the non-relativistic Hamiltonian to $O({\\rm m}c^2)^{-4}$,\nwhere ${\\rm m}c^2$ is the particle's Einstein rest energy. For ${\\bf\nB}||\\hat{\\bf e}_{\\mu}$, the Zeeman $g_{\\mu}$ factor is $2{\\rm\nm}\\sqrt{m_{\\mu}}/m_g^{3/2} + O({\\rm m}c^2)^{-2}$. While propagating in a\ntwo-dimensional (2D) conduction band with $m_3\\gg m_1,m_2$, $g_{||}<<2$,\nconsistent with recent measurements of the temperature $T$ dependence of the\nparallel upper critical induction $B_{c2,||}(T)$ in superconducting monolayer\nNbSe$_2$ and in twisted bilayer graphene. While a particle is in its conduction\nband of an atomically thin one-dimensional metallic chain along $\\hat{\\bf\ne}_{\\mu}$, $g<<2$ for all ${\\bf B}={\\bf\\nabla}\\times{\\bf A}$ directions and\nvanishingly small for ${\\bf B}||\\hat{\\bf e}_{\\mu}$. The quantum spin Hall\nHamiltonian for 2D metals with $m_1=m_2=m_{||}$ is $K[{\\bf E}\\times({\\bf\np}-q{\\bf A})]_{\\perp}\\sigma_{\\perp}+O({\\rm m}c^2)^{-4}$, where ${\\bf E}$ and\n${\\bf p}-q{\\bf A}$ are the planar electric field and gauge-invariant momentum,\n$q=\\mp|e|$ is the particle's charge, $\\sigma_{\\perp}$ is the Pauli matrix\nnormal to the layer, $K=\\pm\\mu_B/(2m_{||}c^2)$, and $\\mu_B$ is the Bohr\nmagneton."
    },
    {
        "anchor": "Spin Relaxation in Isotopically Purified Silicon Quantum Dots: We investigate spin-flip processes of Si quantum dots due to spin-orbit\ncoupling. We utilize the spin-orbit coupling constants related to bulk and\nstructure inversion asymmetry obtained numerically for two dimensional\nheterostructures. We find that the spin-flip rate is very sensitive to these\ncoupling constants. We investigate the nuclei-mediated spin-flip process and\nfind the level of the isotope $^{29}$Si concentration for which this mechanism\nbecome dominant.",
        "positive": "Ultrasensitive, Ultrafast and Gate-Tunable Two-Dimensional\n  Photodetectors in Ternary Rhombohedral ZnIn2S4 for Optical Neural Networks: The demand for high-performance semiconductors in electronics and\noptoelectronics has prompted the expansion of low-dimensional materials\nresearch to ternary compounds. However, photodetectors based on 2D ternary\nmaterials usually suffer from large dark currents and slow response, which\nmeans increased power consumption and reduced performance. Here we report a\nsystematic study of the optoelectronic properties of well-characterized\nrhombohedral ZnIn2S4 (R-ZIS) nanosheets which exhibit an extremely low dark\ncurrent (7 pA at 5 V bias). The superior performance represented by a series of\nparameters surpasses most 2D counterparts. The ultrahigh specific detectivity\n(1.8 x 10^14 Jones), comparably short response time ({\\tau}_rise = 222 {\\mu}s,\n{\\tau}_decay = 158 {\\mu}s) and compatibility with high-frequency operation\n(1000 Hz) are particularly prominent. Moreover, a gate-tunable characteristic\nis observed, which is attributed to photogating and improves the photoresponse\nby two orders of magnitude. Gating technique can effectively modulate the\nphotocurrent-generation mechanism from photoconductive effect to dominant\nphotogating. The combination of ultrahigh sensitivity, ultrafast response and\nhigh gate tunability makes the R-ZIS phototransistor an ideal device for\nlow-energy-consumption and high-frequency optoelectronic applications, which is\nfurther demonstrated by its excellent performance in optical neural networks\nand promising potential in optical deep learning and computing."
    },
    {
        "anchor": "Casimir effect for biaxial anisotropic plates with surface conductivity: The Casimir energy is constructed for a system consisting of two\nsemi-infinite slabs of anisotropic material. Each of them is characterized by\nbulk complex dielectric permittivity tensor and surface conductivity on the\nfree boundary. We found general form of the scattering matrix and Fresnel\ncoefficients for each part of the system by solving Maxwell equations in the\nanisotropic media.",
        "positive": "Engineering long spin coherence times of spin-orbit systems: Spin-orbit coupling fundamentally alters spin qubits, opening pathways to\nimprove the scalability of quantum computers via long distance coupling\nmediated by electric fields, photons, or phonons. It also allows for new\nengineered hybrid and topological quantum systems. However, spin qubits with\nintrinsic spin-orbit coupling are not yet viable for quantum technologies due\nto their short ($\\sim1~\\mu$s) coherence times $T_2$, while qubits with long\n$T_2$ have weak spin-orbit coupling making qubit coupling short-ranged and\nchallenging for scale-up. Here we show that an intrinsic spin-orbit coupled\n\"generalised spin\" with total angular momentum $J=\\tfrac{3}{2}$, which is\ndefined by holes bound to boron dopant atoms in strained $^{28}\\mathrm{Si}$,\nhas $T_2$ rivalling the electron spins of donors and quantum dots in\n$^{28}\\mathrm{Si}$. Using pulsed electron paramagnetic resonance, we obtain\n$0.9~\\mathrm{ms}$ Hahn-echo and $9~\\mathrm{ms}$ dynamical decoupling $T_2$\ntimes, where strain plays a key role to reduce spin-lattice relaxation and the\nlongitudinal electric coupling responsible for decoherence induced by electric\nfield noise. Our analysis shows that transverse electric dipole can be\nexploited for electric manipulation and qubit coupling while maintaining a weak\nlongitudinal coupling, a feature of $J=\\tfrac{3}{2}$ atomic systems with a\nstrain engineered quadrupole degree of freedom. These results establish\nsingle-atom hole spins in silicon with quantised total angular momentum, not\nspin, as a highly coherent platform with tuneable intrinsic spin-orbit coupling\nadvantageous to build artificial quantum systems and couple qubits over long\ndistances."
    },
    {
        "anchor": "Disorder-induced magnetooscillations in bilayer graphene at high bias: Energy spectrum of biased bilayer graphene near the bottom has a\n\"Mexican-hat\"-like shape. For the Fermi level within the Mexican hat we predict\nthat, apart from conventional magnetooscillations which vanish with\ntemperature, there are additional magnetooscillations which are weakly\nsensitive to temperature. These oscillations are also insensitive to a\nlong-range disorder. Their period in magnetic field scales with bias, V, as\nV^2. The origin of these oscillations is the disorder-induced scattering\nbetween electron-like and hole-like Fermi-surfaces, specific for Mexican hat.",
        "positive": "Phonon-assisted tunneling in asymmetric resonant tunneling structures: Based on the dielectric continuum model, we calculated the phonon assisted\ntunneling (PAT) current of general double barrier resonant tunneling structures\n(DBRTSs) including both symmetric and antisymmetric ones. The results indicate\nthat the four higher frequency interface phonon modes (especially the one which\npeaks at either interface of the emitter barrier) dominate the PAT processes,\nwhich increase the valley current and decrease the PVR of the DBRTSs. We show\nthat an asymmetric structure can lead to improved performance."
    },
    {
        "anchor": "Persistent currents in mesoscopic rings and boundary conformal field\n  theory: A tight-binding model of electron dynamics in mesoscopic normal rings is\nstudied using boundary conformal field theory. The partition function is\ncalculated in the low energy limit and the persistent current generated as a\nfunction of an external magnetic flux threading the ring is found. We study the\ncases where there are defects and electron-electron interactions separately.\nThe same temperature scaling for the persistent current is found in each case,\nand the functional form can be fitted, with a high degree of accuracy, to\nexperimental data.",
        "positive": "Numerical study of the Coulomb blockade in an open quantum dot: The Coulomb blockade in an open quantum dot connected to a bulk lead by a\nsingle mode point contact is studied numerically using the path-integral Monte\nCarlo method. The Coulomb oscillation of the average charge and capacitance of\nthe dot is investigated, and is compared with the analytic expression for\nstrong tunneling. At the degeneracy point, we observe logarithmic divergence of\nthe capacitance for strong backscattering at the point contact. This\nobservation supports the conjecture that the nature of the present system at\nthe degeneracy point is described by the two-channel Kondo problem for an\narbitrary strength of tunneling."
    },
    {
        "anchor": "Energy redistribution between quasiparticles in mesoscopic silver wires: We have measured with a tunnel probe the energy distribution function of\nquasiparticles in silver diffusive wires connected to two large pads\n(``reservoirs''), between which a bias voltage was applied. From the dependence\nin energy and bias voltage of the distribution function we have inferred the\nenergy exchange rate between quasiparticles. In contrast with previously\nobtained results on copper and gold wires, these data on silver wires can be\nwell interpreted with the theory of diffusive conductors either solely, or\nassociated with another mechanism, possibly the coupling to two-level systems.",
        "positive": "Adiabatic quantum pumping in graphene with magnetic barriers: We study an adiabatic quantum pump effect in a two terminal graphene device\nwith two oscillating square electric barriers and a stationary magnetic barrier\nusing the scattering matrix approach. The model employs the low-energy Dirac\napproximation and incorporates the possible existence of a finite band gap in\ngraphene spectrum. We show that in this case valley-polarized and pure valley\ncurrents can be pumped due to the valley symmetry breaking. For a\n\\delta-function magnetic barrier we present analytical expressions for bilinear\ntotal and valley pumping responses. These results are compared to numerical\nones for a double \\delta-function, a square and a triple square magnetic\nbarriers."
    },
    {
        "anchor": "Superconducting Quantum Interference Devices Made of Sb-doped Bi2Se3\n  Topological Insulator Nanoribbons: We report the fabrication and characterization of superconducting quantum\ninterference devices (SQUIDs) made of Sb-doped Bi2Se3 topological insulator\n(TI) nanoribbon (NR) contacted with PbIn superconducting electrodes. When an\nexternal magnetic field was applied along the NR axis, the TI NR exhibited\nperiodic magneto-conductance oscillations, the so-called Aharonov-Bohm\noscillations, owing to one-dimensional subbands. Below the superconducting\ntransition temperature of PbIn electrodes, we observed supercurrent flow\nthrough TI NR-based SQUID. The critical current periodically modulates with a\nmagnetic field perpendicular to the SQUID loop, revealing that the periodicity\ncorresponds to the superconducting flux quantum. Our experimental observations\ncan be useful to explore Majorana bound states (MBS) in TI NR, promising for\ndeveloping topological quantum information devices.",
        "positive": "Transport discovery of emerging robust helical surface states in $Z_2=0$\n  systems: We study the possibility of realizing robust helical surface states in\n$Z_2=0$ systems. We find that the combination of anisotropy and finite-size\nconfinement leads to the emergence of robust helical edge states in both 2D and\n3D $Z_2=0$ systems. By investigating an anisotropic Bernevig-Hughes-Zhang model\nin a finite sample, we demonstrate that the transport manifestation of the\nsurface states is robust against non-magnetic disorder, resembling that of a\n$Z_2 = 1$ phase. Notably, the effective energy gap for the robust helical\nstates can be efficiently engineered, allowing for potential applications as\nvalley filters and valley valves. The realization of emerging robust helical\nsurface states in realistic material is also discussed."
    },
    {
        "anchor": "Robustness of the quantum Hall effect, sample size versus sample\n  topology, and quality control management of III-V molecular beam epitaxy: We measure the IQHE on macroscopic (1.5cm x 1.5cm) \"quick 'n' dirty\" prepared\nIII-V heterostructure samples with van der Pauw and modified Corbino geometries\nat 1.3 K. We compare our results with (i) data taken on smaller specimens,\namong them samples with a standard Hall bar geometry, (ii) results of our\nnumerical analysis taking inhomogenities of the 2DEG into account. Our main\nfinding is a confirmation of the expected robustness of the IQHE which favours\nthe development of wide plateaux for small filling factors and very large\nsample sizes (here with areas 10,000 times larger than in standard\narrangements).",
        "positive": "Gate-Variable Mid-Infrared Optical Transitions in a\n  $(Bi_{1-x}Sb_x)_2Te_3$ Topological Insulator: We report mid-infrared spectroscopy measurements of an electrostatically\ngated topological insulator, in which we observe several percent modulation of\ntransmittance and reflectance of (Bi1-xSbx)2Te3 films as gating shifts the\nFermi level. Infrared transmittance measurements of gated (Bi1-xSbx)2Te3 films\nwere enabled by use of an epitaxial lift-off method for large-area transfer of\ntopological insulator films from infrared-absorbing SrTiO3 growth substrates to\nthermal oxidized silicon substrates. We combine these optical experiments with\ntransport measurements and angle-resolved photoemission spectroscopy to\nidentify the observed spectral modulation as a gate-driven transfer of spectral\nweight between both bulk and topological surface channels and interband and\nintraband channels. We develop a model for the complex permittivity of gated\n(Bi1-xSbx)2Te3, and find a good match to our experimental data. These results\nopen the path for layered topological insulator materials as a new candidate\nfor tunable infrared optics and highlight the possibility of switching\ntopological optoelectronic phenomena between bulk and spin-polarized surface\nregimes."
    },
    {
        "anchor": "Towards quantum optics and entanglement with electron spin ensembles in\n  semiconductors: We discuss a technique and a material system that enable the controlled\nrealization of quantum entanglement between spin-wave modes of electron\nensembles in two spatially separated pieces of semiconductor material. The\napproach uses electron ensembles in GaAs quantum wells that are located inside\noptical waveguides. Bringing the electron ensembles in a quantum Hall state\ngives selection rules for optical transitions across the gap that can\nselectively address the two electron spin states. Long-lived superpositions of\nthese electron spin states can then be controlled with a pair of optical fields\nthat form a resonant Raman system. Entangled states of spin-wave modes are\nprepared by applying quantum-optical measurement techniques to optical signal\npulses that result from Raman transitions in the electron ensembles.",
        "positive": "Transmissions of gapped graphene in tilting and oscillating barriers: We examine the transmissions in gapped graphene through a combination of\ndouble barriers tilting and time-oscillating potential. The latter introduces\nextra sidebands to the transmission probability, which occur at energy levels\ndetermined by the frequency and incident energy. The sidebands are generated as\na result of the absorption or emission of photons yielded from the oscillating\npotential. Our results indicate that transmission probabilities in gapped\ngraphene can be manipulated by regulating the incident energy, the oscillating\npotential, or the distance between two barriers and their heights. It has been\nobserved that the transmissions may be impeded or prevented by tuning the gap."
    },
    {
        "anchor": "Disorder and interactions in systems out of equilibrium: The exact\n  independent-particle picture from density functional theory: Density functional theory (DFT) exploits an independent-particle-system\nconstruction to replicate the densities and current of an interacting system.\nThis construction is used here to access the exact effective potential and bias\nof non-equilibrium systems with disorder and interactions. Our results show\nthat interactions smoothen the effective disorder landscape, but do not\nnecessarily increase the current, due to the competition of disorder screening\nand effective bias. This puts forward DFT as a diagnostic tool to understand\ndisorder screening in a wide class of interacting disordered systems.",
        "positive": "Fidimag -- a finite difference atomistic and micromagnetic simulation\n  package: Fidimag is an open-source scientific code for the study of magnetic materials\nat the nano- or micro-scale using either atomistic or finite difference\nmicromagnetic simulations, which are based on solving the\nLandau-Lifshitz-Gilbert equation. In addition, it implements simple procedures\nfor calculating energy barriers in the magnetisation through variants of the\nnudged elastic band method. This computer software has been developed with the\naim of creating a simple code structure that can be readily installed, tested,\nand extended. An agile development approach was adopted, with a strong emphasis\non automated builds and tests, and reproducibility of results. The main code\nand interface to specify simulations are written in Python, which allows simple\nand readable simulation and analysis configuration scripts. Computationally\ncostly calculations are written in C and exposed to the Python interface as\nCython extensions. Docker containers are shipped for a convenient setup\nexperience. The code is freely available on GitHub and includes documentation\nand examples in the form of Jupyter notebooks."
    },
    {
        "anchor": "NOT gate response in a mesoscopic ring: An exact result: We explore NOT gate response in a mesoscopic ring threaded by a magnetic flux\n$\\phi$. The ring is attached symmetrically to two semi-infinite one-dimensional\nmetallic electrodes and a gate voltage, viz, $V_a$, is applied in one arm of\nthe ring which is treated as the input of the NOT gate. The calculations are\nbased on the tight-binding model and the Green's function method, which\nnumerically compute the conductance-energy and current-voltage characteristics\nas functions of the ring-to-electrodes coupling strength, magnetic flux and\ngate voltage. Our theoretical study shows that, for $\\phi=\\phi_0/2$\n($\\phi_0=ch/e$, the elementary flux-quantum) a high output current (1) (in the\nlogical sense) appears if the input to the gate is low (0), while a low output\ncurrent (0) appears when the input to the gate is high (1). It clearly exhibits\nthe NOT gate behavior and this aspect may be utilized in designing an\nelectronic logic gate.",
        "positive": "Gate tuneable beamsplitter in ballistic graphene: We present a beam splitter in a suspended, ballistic, multiterminal, bilayer\ngraphene device. By using local bottomgates, a p-n interface tilted with\nrespect to the current direction can be formed. We show that the p-n interface\nacts as a semi-transparent mirror in the bipolar regime and that the\nreflectance and transmittance of the p-n interface can be tuned by the gate\nvoltages. Moreover, by studying the conductance features appearing in magnetic\nfield, we demonstrate that the position of the p-n interface can be moved by\n$1\\,\\mu$m. The herein presented beamsplitter device can form the basis of\nelectron-optic interferometers in graphene."
    },
    {
        "anchor": "Modelling of tunnelling currents in Hf-based gate stacks as a function\n  of temperature and extraction of material parameters: In this paper we show that through electrical characterization and detailed\nquantum simulations of the capacitance-voltage and current-voltage\ncharacteristics it is possible to extract a series of material parameters of\nalternative gate dielectrics. We have focused on HfO2 and HfSiXOYNZ gate stacks\nand have extracted information on the nature of localized states in the\ndielectric responsible for a trap-assisted tunneling current component and for\nthe temperature behavior of the I-V characteristics. Simulations are based on a\n1D Poisson-Schrdinger solver capable to provide the pure tunneling current and\nTrap Assisted Tunneling component. Energy and capture cross section of traps\nresponsible for TAT current have been extracted.",
        "positive": "Mesoscopic supercurrent transistor controlled by nonequilibrium cooling: The distinctive quasiparticle distribution existing under nonequilibrium in a\nsuperconductor-insulator-normal metal-insulator-superconductor (SINIS)\nmesoscopic line is proposed as a novel tool to control the supercurrent\nintensity in a long Josephson weak link. We present a description of this\nsystem in the framework of the diffusive-limit quasiclassical Green-function\ntheory and take into account the effects of inelastic scattering with arbitrary\nstrength. Supercurrent enhancement and suppression, including a marked\ntransition to a $\\pi$-junction are striking features leading to a fully tunable\nstructure. The role of the degree of nonequilibrium, temperature, and materials\nchoice as well as features like noise, switching time, and current and power\ngain are also addressed."
    },
    {
        "anchor": "Transport properties of Co in Cu(100) from first principles: The electronic transport properties of a point-contact system formed by a\nsingle Co atom adsorbed on Cu (100) and contacted by a copper tip is evaluated\nin the presence of intra-atomic Coulomb interactions and spin-orbit coupling.\nThe calculations are performed using equilibrium Green's functions evaluated\nwithin density functional theory completed with a Hubbard $U$ term and\nspin-orbit interaction, as implemented in the Gollum package. We show that the\ncontribution to the transmission between electrodes of spin-flip components is\nnegative and scaling as $\\lambda^2/\\Gamma^2$ where $\\lambda$ is the SOC and\n$\\Gamma$ the Co atom-electrode coupling. Hence, due to this unfavorable ratio,\nSOC effects in transport in this system are small. However, we show that the\nspin-flip transmission component can increase by two orders of magnitude\ndepending on the value of the Hubbard $U$ term. These effects are particularly\nimportant in the contact regime because of the prevalence of $d$-electron\ntransport, while in the tunneling regime, transport is controlled by the\n$sp$-electron transmission and results are less dependent on the values of $U$\nand SOC. Using our electronic structure and the elastic transmission\ncalculations, we discuss the effect of $U$ and SOC on the well-known Kondo\neffect of this system.",
        "positive": "Long-Range Repulsion Between Spatially Confined van der Waals Dimers: It is an undisputed textbook fact that non-retarded van der Waals (vdW)\ninteractions between isotropic dimers are attractive, regardless of the\npolarizability of the interacting systems or spatial dimensionality. The\nuniversality of vdW attraction is attributed to the dipolar coupling between\nfluctuating electron charge densities. Here we demonstrate that the long-range\ninteraction between \\textit{spatially confined} vdW dimers becomes repulsive\nwhen accounting for the full Coulomb interaction between charge fluctuations.\nOur analytic results are obtained by using the Coulomb potential as a\nperturbation over dipole-correlated states for two quantum harmonic oscillators\nembedded in spaces with reduced dimensionality, however the long-range\nrepulsion is expected to be a general phenomenon for spatially-confined quantum\nsystems. We suggest optical experiments to test our predictions, analyze their\nrelevance in the context of intermolecular interactions in nanoscale\nenvironments, and rationalize the recent observation of anomalously strong\nscreening of the lateral vdW interactions between aromatic hydrocarbons\nadsorbed on metal surfaces."
    },
    {
        "anchor": "Random Green's function method for large-scale electronic structure\n  calculation: We report a linear-scaling random Green's function (rGF) method for\nlarge-scale electronic structure calculation. In this method, the rGF is\ndefined on a set of random states to stochastically express the density matrix,\nand rGF is calculated with the linear-scaling computational cost. We show the\nrGF method is generally applicable to the nonorthogonal localized basis, and\ncircumvent the large Chebyshev expansion for the density matrix. As a\ndemonstration, we implement rGF with density-functional Tight-Binding method\nand apply it to self-consistently calculate water clusters up 9984 H2Os. We\nfind the rGF method combining with a simple fragment correction can reach an\nerror of ~1meV per H2O in total energy, compared to the deterministic\ncalculations, due to the self-average. The development of rGF method advances\nthe stochastic electronic structure theory to a new stage of the efficiency and\napplicability.",
        "positive": "Role of diffusive surface scattering in nonlocal plasmonics: The recent generalised nonlocal optical response (GNOR) theory for plasmonics\nis analysed, and its main input parameter, namely the complex hydrodynamic\nconvection-diffusion constant, is quantified in terms of enhanced Landau\ndamping due to diffusive surface scattering of electrons at the surface of the\nmetal. GNOR has been successful in describing plasmon damping effects, in\naddition to the frequency shifts originating from induced-charge screening,\nthrough a phenomenological electron diffusion term implemented into the\ntraditional hydrodynamic Drude model of nonlocal plasmonics. Nevertheless, its\nmicroscopic derivation and justification is still missing. Here we discuss how\nthe inclusion of a diffusion-like term in standard hydrodynamics can serve as\nan efficient vehicle to describe Landau damping without resorting to\ncomputationally demanding quantum-mechanical calculations, and establish a\ndirect link between this term and the Feibelman $d$ parameter for the centroid\nof charge. Our approach provides a recipe to connect the phenomenological\nfundamental GNOR parameter to a frequency-dependent microscopic\nsurface-response function. We therefore tackle one of the principal limitations\nof the model, and further elucidate its range of validity and limitations, thus\nfacilitating its proper application in the framework of nonclassical\nplasmonics."
    },
    {
        "anchor": "Total Angular Momentum Conservation During Tunnelling through\n  Semiconductor Barriers: We have investigated the electrical transport through strained\np-Si/Si_{1-x}Ge_x double-barrier resonant tunnelling diodes. The confinement\nshift for diodes with different well width, the shift due to a central\npotential spike in a well, and magnetotunnelling spectroscopy demonstrate that\nthe first two resonances are due to tunnelling through heavy hole levels,\nwhereas there is no sign of tunnelling through the first light hole state. This\ndemonstrates for the first time the conservation of the total angular momentum\nin valence band resonant tunnelling. It is also shown that conduction through\nlight hole states is possible in many structures due to tunnelling of carriers\nfrom bulk emitter states.",
        "positive": "Monolithically Patterned Wide-Narrow-Wide All-Graphene Devices: We investigate theoretically the performance advantages of all-graphene\nnanoribbon field-effect transistors (GNRFETs) whose channel and source/drain\n(contact) regions are patterned monolithically from a two-dimensional single\nsheet of graphene. In our simulated devices, the source/drain and interconnect\nregions are composed of wide graphene nanoribbon (GNR) sections that are\nsemimetallic, while the channel regions consist of narrow GNR sections that\nopen semiconducting bandgaps. Our simulation employs a fully atomistic model of\nthe device, contact and interfacial regions using tight-binding theory. The\nelectronic structures are coupled with a self-consistent three-dimensional\nPoisson's equation to capture the nontrivial contact electrostatics, along with\na quantum kinetic formulation of transport based on non-equilibrium Green's\nfunctions (NEGF). Although we only consider a specific device geometry, our\nresults establish several general performance advantages of such monolithic\ndevices (besides those related to fabrication and patterning), namely the\nimproved electrostatics, suppressed short-channel effects, and Ohmic contacts\nat the narrow-to-wide interfaces."
    },
    {
        "anchor": "Cancellation of Spin-Orbit Effects in Quantum Gates Based on the\n  Exchange Coupling in Quantum Dots: We study the effect of the spin-orbit interaction on quantum gate operations\nbased on the spin exchange coupling where the qubit is represented by the\nelectron spin in a quantum dot or a similar nanostructure. Our main result is\nthe exact cancellation of the spin-orbit effects in the sequence producing the\nquantum XOR gate for the ideal case where the pulse shapes of the exchange and\nspin-orbit interactions are identical. For the non-ideal case, the two pulse\nshapes can be made almost identical and the gate error is strongly suppressed\nby two small parameters, the spin-orbit constant and the deviation of the two\npulse shapes. We show that the dipole-dipole interaction leads only to very\nsmall errors in the XOR gate.",
        "positive": "Effects of the removal of Ta capping layer on the magnetization dynamics\n  of Permalloy thin films: We have investigated the spin wave dynamics of Permalloy (Py) thin films with\nand without a Ta capping layer for varying Py thickness (15 nm, 20 nm and 30\nnm) using all optical time-resolved magneto-optical Kerr effect measurements.\nXPS measurements confirm the oxidation of the originally-prepared samples and\nalso that the removal of the Ta capping layer is achievable by a few sputtering\ncycles. The magnetic field strength dependencies of the spin wave modes with\nthe variation of the Py film thickness for the samples are studied. We observe\nthat the presence of the Ta capping layer reduces the precessional frequencies\nof the samples while the samples without a Ta capping layer enhance the role of\nPy thickness. We also observe that the decay time of spin waves is highly\ndependent on the top layer of the samples. The decay time increases with\nincreasing Py thicknesses for Ta/Py/Ta samples implying that the enhancement of\ndecay time is caused by the Ta/Py/Ta interfaces. Whereas, for Ta/Py samples the\ndecay time decreases with increasing Py thickness. The results of this work\nextend the knowledge on the magnetization dynamics of Py thin films giving\ninformation on how to resume and even enhance the spin mobility after a\ndeleterious oxidation process. This can open new scenarios on the building\nprocess and on the maintenance of fast magnetic switching devices."
    },
    {
        "anchor": "Barrier Lowering and Backscattering Extraction in Short-Channel MOSFETs: In this work we propose a fully experimental method to extract the barrier\nlowering in short-channel saturated MOSFETs using the Lundstrom backscattering\ntransport model in a one sub-band approximation and carrier degeneracy. The\nknowledge of the barrier lowering at the operative bias point in the inversion\nregime is of fundamental importance in device scaling. At the same time we\nobtain also an estimate of the backscattering ratio and of the saturation\ninversion charge. Respect to previously reported works on extraction of\ntransport parameters based on the Lundstrom model, our extraction method is\nfully consistent with it, whereas other methods make a number of approximations\nin the calculation of the saturation inversion charge which are inconsistent\nwith the model. The proposed experimental extraction method has been validated\nand applied to results from device simulation and measurements on short-channel\npoly-Si/SiON gate nMOSFETs with gate length down to 70 nm. Moreover we propose\nan extension of the backscattering model to the case of 2D geometries (e.g.\nbulk MOSFETs). We found that, in this case, the backscattering is governed by\nthe carrier transport in a few nanometers close to the silicon/oxide interface\nand that the value of the backscattering ratio obtained with a 1D approach can\nbe significantly different from the real 2D value.",
        "positive": "Diagrammatic real-time approach to adiabatic pumping through metallic\n  single-electron devices: We present a real-time diagrammatic formalism to study adiabatic pumping in\nchains of tunnel-coupled metallic islands. This approach is based on an\nexpansion to linear order in the frequency of the time-dependent parameters and\non a systematic perturbation expansion in the tunnel-coupling strength. We\napply our formalism to a single-island and a double-island system. In the\nsingle-island setup, we find that the first-order contribution in the\ntunnel-coupling strength is purely due to the renormalization of the\ncharging-energy gap. In the double-island system, we investigate the transition\nbetween weak and strong pumping."
    },
    {
        "anchor": "Quantum correlations of light and matter through environmental\n  transitions: One aspect of solid-state photonic devices that distinguishes them from their\natomic counterparts is the unavoidable interaction between system excitations\nand lattice vibrations of the host material. This coupling may lead to\nsurprising departures in emission properties between solid-state and atomic\nsystems. Here we predict a striking and important example of such an effect. We\nshow that in solid-state cavity quantum electrodynamics, interactions with the\nhost vibrational environment can generate quantum cavity-emitter correlations\nin regimes that are semiclassical for atomic systems. This behaviour, which can\nbe probed experimentally through the cavity emission properties, heralds a\nfailure of the semiclassical approach in the solid-state, and challenges the\nnotion that coupling to a thermal bath supports a more classical description of\nthe system. Furthermore, it does not rely on the spectral details of the host\nenvironment under consideration and is robust to changes in temperature. It\nshould thus be of relevance to a wide variety of photonic devices.",
        "positive": "Two-and three-qubit room-temperature graphene quantum gates: Proposed configurations for the implementation of graphene-based CNOT and\nToffoli gates working at room temperature are presented. These two logic gates,\nessential for any quantum computing algorithm, involve ballistic Y junctions\nfor qubit implementation, quantum interference for qubit interaction and\noblique gates for optimizing the output, and can be fabricated using existing\nnanolitographical techniques. The proposed configurations of CNOT and Toffoli\nquantum logic gates are based on the very large mean-free-paths of carriers in\ngraphene at room temperature."
    },
    {
        "anchor": "Electrons and composite Dirac fermions in the lowest Landau level: We construct an action for the composite Dirac fermion consistent with\nsymmetries of electrons projected to the lowest Landau level. First we\nconstruct a generalization of the $g=2$ electron that gives a smooth massless\nlimit on any curved background. Using the symmetries of the microscopic\nelectron theory in this massless limit we find a number of constraints on any\nlow-energy effective theory. We find that any low-energy description must\ncouple to a geometry which exhibits nontrivial curvature even on flat\nspace-times. Any composite fermion must have an electric dipole moment\nproportional and orthogonal to the composite fermion's wavevector. We construct\nthe effective action for the composite Dirac fermion and calculate the physical\nstress tensor and current operators for this theory.",
        "positive": "Electron transport in an open mesoscopic metallic ring: We study electron transport in a normal-metal ring modeled by the tight\nbinding lattice Hamiltonian, coupled to two electron reservoirs. First,\nButtiker's model of incorporating inelastic scattering, hence decoherence and\ndissipation, has been extended by connecting each site of the open ring to\none-dimensional leads for uniform dephasing in the ring threaded by magnetic\nflux. We show with this extension conductance remains symmetric under flux\nreversal, and Aharonov-Bohm oscillations with changing magnetic flux reduce to\nzero as a function of the decoherence parameter, thus indicating dephasing in\nthe ring. This extension enables us to find local chemical potential profiles\nof the ring sites with changing magnetic flux and the decoherence parameter\nanalogously to the four probe measurement. The local electrochemical potential\noscillates in the ring sites because of quantum-interference effects. It\npredicts that measured four-point resistance also fluctuates and even can be\nnegative. Then we point out the role of the closed ring's electronic\neigenstates in the persistent current around Fano antiresonances of an\nasymmetric open ring for both ideal leads and tunnel barriers. Determining the\nreal eigenvalues of the non-Hermitian effective Hamiltonian of the ring, we\nshow that there exist discrete bound states in the continuum of scattering\nstates for the asymmetric ring even in the absence of magnetic flux. Our\napproach involves quantum Langevin equations and non-equilibrium Green's\nfunctions."
    },
    {
        "anchor": "Anderson transition of three dimensional phonon modes: Anderson transition of the phonon modes is studied numerically. The critical\nexponent for the divergence of the localization length is estimated using the\ntransfer matrix method, and the statistics of the modes is analyzed. The latter\nis shown to be in excellent agreement with the energy level statistics of the\ndisrodered electron system belonging to the orthogonal universality class.",
        "positive": "Quantum Tunneling of the Order Parameter in Superconducting Nanowires: Quantum tunneling of the superconducting order parameter gives rise to the\nphase slippage process which controls the resistance of ultra-thin\nsuperconducting wires at sufficiently low temperatures. If the quantum phase\nslip rate is high, superconductivity is completely destroyed by quantum\nfluctuations and the wire resistance never decreases below its normal state\nvalue. We present a detailed microscopic theory of quantum phase slips in\nhomogeneous superconducting nanowires. Focusing our attention on relatively\nshort wires we evaluate the quantum tunneling rate for phase slips, both the\nquasiclassical exponent and the pre-exponential factor. In very thin and dirty\nmetallic wires the effect is shown to be clearly observable even at $T \\to 0$.\nOur results are fully consistent with recent experimental findings [A.\nBezryadin, C.N. Lau, and M. Tinkham, Nature {\\bf 404}, 971 (2000)] which\nprovide direct evidence for the effect of quantum phase slips."
    },
    {
        "anchor": "Bolometer operating at the threshold for circuit quantum electrodynamics: Radiation sensors based on the heating effect of the absorbed radiation are\ntypically relatively simple to operate and flexible in terms of the input\nfrequency. Consequently, they are widely applied, for example, in gas\ndetection, security, THz imaging, astrophysical observations, and medical\napplications. A new spectrum of important applications is currently emerging\nfrom quantum technology and especially from electrical circuits behaving\nquantum mechanically. This circuit quantum electrodynamics (cQED) has given\nrise to unprecedented single-photon detectors and a quantum computer supreme to\nthe classical supercomputers in a certain task. Thermal sensors are appealing\nin enhancing these devices since they are not plagued by quantum noise and are\nsmaller, simpler, and consume about six orders of magnitude less power than the\ncommonly used traveling-wave parametric amplifiers. However, despite great\nprogress in the speed and noise levels of thermal sensors, no bolometer to date\nhas proven fast and sensitive enough to provide advantages in cQED. Here, we\nexperimentally demonstrate a bolometer surpassing this threshold with a noise\nequivalent power of $30\\, \\rm{zW}/\\sqrt{\\rm{Hz}}$ on par with the current\nrecord while providing two-orders of magnitude shorter thermal time constant of\n500 ns. Importantly, both of these characteristic numbers have been measured\ndirectly from the same device, which implies a faithful estimation of the\ncalorimetric energy resolution of a single 30-GHz photon. These improvements\nstem from the utilization of a graphene monolayer as the active material with\nextremely low specific heat. The minimum demonstrated time constant of 200 ns\nfalls greatly below the state-of-the-art dephasing times of roughly 100 {\\mu}s\nfor superconducting qubits and meets the timescales of contemporary readout\nschemes thus enabling the utilization of thermal detectors in cQED.",
        "positive": "Spin wave damping in periodic and quasiperiodic magnonic structures: We investigated the lifetime of spin wave eigenmodes in periodic and\nquasiperiodic sequences of Py and Co wires. Those materials differ\nsignificantly in damping coefficients, therefore, the spatial distribution of\nthe mode amplitude within the structure is important for the lifetime of\ncollective spin wave excitations. Modes of the lower frequencies prefer to\nconcentrate in Py wires, because of the lower FMR frequency for this material.\nThis inhomogeneous distribution of amplitude of modes (with lower amplitude in\nmaterial of higher damping and with higher amplitude in material of lower\ndamping) is preferable for extending the lifetime of the collective excitations\nbeyond the volume average of lifetimes for solid materials. We established the\nrelation between the profile of the mode and its lifetime for periodic and\nquasiperiodic structures. We performed also the comparative studies in order to\nfind the differences resulting from complexity of the structure and enhancement\nof localization in quasiperiodic system on the lifetime of spin waves."
    },
    {
        "anchor": "Thermoelectric Features of Magnetic Doped Graphene Nanoribbons: Thermoelectric properties of Graphene Nanoribbons doped by magnetic\nimpurities Fe and Co are carried out in room temperature. We report on a study\nof the band structure dependent properties such as electrical conductivity,\ncharge of carriers and Seebeck coefficients. We investigate the thermoelectric\nproperties using the Semi-classical Boltzmann method. The electronic band\nstructure of doped nanoribbons are evaluated by using density-functional theory\nin which the Hubbard interaction is considered. In this work we compare the\ndifferent types of the nanoribbons and their thermoelectric features in the\npresence and absence of the magnetic impurities and discuss the importance of\nthe distance between impurities and the edge of the nanoribbons.",
        "positive": "Double-periodic Josephson junctions in a quantum dissipative environment: Embedded in an ohmic environment, the Josephson current peak can transfer\npart of its weight to finite voltage and the junction becomes resistive. The\ndissipative environment can even suppress the superconducting effect of the\njunction via a quantum phase transition occuring when the ohmic resistance\n$R_s$ exceeds the quantum resistance $R_{q}=h/(2e)^2$. For a topological\njunction hosting Majorana bound states with a $4 \\pi$ periodicity of the\nsuperconducting phase, the phase transition is shifted to $4 R_{q}$. We\nconsider a Josephson junction mixing the $2 \\pi$ and $4 \\pi$ periodicities\nshunted by a resistor, with a resistance between $R_q$ and $4 R_q$. Starting\nwith a quantum circuit model, we derive the non-monotonic temperature\ndependence of its differential resistance resulting from the competition\nbetween the two periodicities; the $4 \\pi$ periodicity dominating at the lowest\ntemperatures. The non-monotonic behaviour is first revealed by straightforward\nperturbation theory and then substantiated by a fermionization to exactly\nsolvable models when $R_s=2R_{q}$: the model is mapped onto a helical wire\ncoupled to a topological superconductor when the Josephson energy is small and\nto the Emery-Kivelson line of the two-channel Kondo model in the opposite case."
    },
    {
        "anchor": "Non-adiabatic Kohn-anomaly in a doped graphene monolayer: We compute, from first-principles, the frequency of the E2g, Gamma phonon\n(Raman G-band) of graphene, as a function of the charge doping. Calculations\nare done using i) the adiabatic Born-Oppenheimer approximation and ii)\ntime-dependent perturbation theory to explore dynamic effects beyond this\napproximation. The two approaches provide very different results. While, the\nadiabatic phonon frequency weakly depends on the doping, the dynamic one\nrapidly varies because of a Kohn anomaly. The adiabatic approximation is\nconsidered valid in most materials. Here, we show that doped graphene is a\nspectacular example where this approximation miserably fails.",
        "positive": "Universal non-Hermitian skin effect in two and higher dimensions: Skin effect, experimentally discovered in one dimension, describes the\nphysical phenomenon that on an open chain, an extensive number of eigenstates\nof a non-Hermitian hamiltonian are localized at the end(s) of the chain. Here\nin two and higher dimensions, we establish a theorem that the skin effect\nexists, if and only if periodic-boundary spectrum of the hamiltonian covers a\nfinite area on the complex plane. This theorem establishes the universality of\nthe effect, because the above condition is satisfied in almost every generic\nnon-Hermitian hamiltonian, and, unlike in one dimension, is compatible with all\nspatial symmetries. We propose two new types of skin effect in two and higher\ndimensions: the corner-skin effect where all eigenstates are localized at one\ncorner of the system, and the geometry-dependent-skin effect where skin modes\ndisappear for systems of a particular shape, but appear on generic polygons. An\nimmediate corollary of our theorem is that any non-Hermitian system having\nexceptional points (lines) in two (three) dimensions exhibits skin effect,\nmaking this phenomenon accessible to experiments in photonic crystals, Weyl\nsemimetals, and Kondo insulators."
    },
    {
        "anchor": "Bistability of the Nuclear Polarisation created through optical pumping\n  in InGaAs Quantum Dots: We show that optical pumping of electron spins in individual InGaAs quantum\ndots leads to strong nuclear polarisation that we measure via the Overhauser\nshift (OHS) in magneto-photoluminescence experiments between 0 and 4T. We find\na strongly non-monotonous dependence of the OHS on the applied magnetic field,\nwith a maximum nuclear polarisation of 40% for intermediate magnetic fields. We\nobserve that the OHS is larger for nuclear fields anti-parallel to the external\nfield than in the parallel configuration. A bistability in the dependence of\nthe OHS on the spin polarization of the optically injected electrons is found.\nAll our findings are qualitatively understood with a model based on a simple\nperturbative approach.",
        "positive": "Valley polarization in MoS2 monolayers by optical pumping: We report experimental evidences on selective occupation of the degenerate\nvalleys in MoS2 monolayers by circularly polarized optical pumping. Over 30%\nvalley polarization has been observed at K and K' valley via the polarization\nresolved luminescence spectra on pristine MoS2 monolayers. It demonstrates one\nviable way to generate and detect valley polarization towards the conceptual\nvalleytronics applications with information carried by the valley index."
    },
    {
        "anchor": "Quantum geometry beyond projective single bands: The past few years have seen a revived interest in quantum geometrical\ncharacterizations of band structures due to the rapid development of\ntopological insulators and semi-metals. Although the metric tensor has been\nconnected to many geometrical concepts for single bands, the exploration of\nthese concepts to a multi-band paradigm still promises a new field of interest.\nFormally, multi-band systems, featuring in particular degeneracies, have been\nrelated to projective spaces, explaining also the success of relating quantum\ngeometrical aspects of flat band systems, albeit usually in the single band\npicture. Here, we propose a different route involving Pl\\\"ucker embeddings to\nrepresent arbitrary classifying spaces, being the essential objects that encode\n$all$ the relevant topology.This paradigm allows for the quantification of\ngeometrical quantities directly in readily manageable vector spaces that a\npriori do not involve projectors or the need of flat band conditions. As a\nresult, our findings are shown to pave the way for identifying new geometrical\nobjects and defining metrics in arbitrary multi-band systems, especially beyond\nthe single flatband limit, promising a versatile tool that can be applied in\ncontexts that range from response theories to finding quantum volumes and\nbounds on superfluid densities as well as possible quantum computations.",
        "positive": "Extracting the Dispersion of Periodic Lossless LC Circuits Using White\n  Noise: The spectral energy density (SED) method is used to obtain the phonon\ndispersion of materials in molecular dynamics codes, e.g., LAMMPS. We show how\nthe electric analog of the SED method can be done using commercial circuit\nsimulators to find the dispersion of periodic lossless LC circuits. The purpose\nof this article is (a) to demonstrate how SED proves useful, should the\nanalytic methods of calculating dispersion of a circuit render difficult e.g.,\ndue to nonlinearity or having large number of elements in each unit-cell, and\n(b) to show how the concepts like Brillouin zone (BZ), dispersion (or band\nstructure), zone folding, gap formation, and avoided crossing can be taught to\nstudents of electrical engineering by highlighting the analogies between\nphonons and periodic circuits. This analogy also suggests that thermal devices,\ne.g., heat rectifiers can be simulated and understood using commercial circuit\nsimulators."
    },
    {
        "anchor": "Orthogonality Catastrophe in Parametric Random Matrices: We study the orthogonality catastrophe due to a parametric change of the\nsingle-particle (mean field) Hamiltonian of an ergodic system. The Hamiltonian\nis modeled by a suitable random matrix ensemble. We show that the overlap\nbetween the original and the parametrically modified many-body ground states,\n$S$, taken as Slater determinants, decreases like $n^{-k x^2}$, where $n$ is\nthe number of electrons in the systems, $k$ is a numerical constant of the\norder of one, and $x$ is the deformation measured in units of the typical\ndistance between anticrossings. We show that the statistical fluctuations of\n$S$ are largely due to properties of the levels near the Fermi energy.",
        "positive": "Voltage controlled exchange energies of a two electron silicon double\n  quantum dot with and without charge defects in the dielectric: Quantum dots are artificial atoms used for a multitude of purposes. Charge\ndefects are commonly present and can significantly perturb the designed energy\nspectrum and purpose of the dots. Voltage controlled exchange energy in silicon\ndouble quantum dots (DQD) represents a system that is very sensitive to charge\nposition and is of interest for quantum computing. We calculate the energy\nspectrum of the silicon double quantum dot system using a full configuration\ninteraction that uses tight binding single particle wavefunctions. This\napproach allows us to analyze atomic scale charge perturbations of the DQD\nwhile accounting for the details of the complex momentum space physics of\nsilicon (i.e., valley and valley-orbit physics). We analyze how the energy\nlevels and exchange curves for a DQD are affected by nearby charge defects at\nvarious positions relative to the dot, which are consistent with defects\nexpected in the metal-oxide-semiconductor system."
    },
    {
        "anchor": "Electronic structure of graphene beyond the linear dispersion regime: Among the many interesting features displayed by graphene, one of the most\nattractive is the simplicity with which its electronic structure can be\ndescribed. The study of its physical properties is significantly simplified by\nthe linear dispersion relation of electrons in a narrow range around the Fermi\nlevel. Unfortunately, the mathematical simplicity of graphene electrons is only\nlimited to this narrow energy region and is useless when dealing with problems\nthat involve energies outside the linear dispersion part of the spectrum. In\nthis letter we remedy this limitation by deriving a set of closed-form\nanalytical expressions for the real-space single-electron Green function of\ngraphene which are valid across an enormous fraction of the energy spectrum. By\nextending to a wider energy range the simplicity with which graphene electrons\nare described, it is now possible to derive more mathematically transparent and\ninsightful expressions for a number of physical properties that involve higher\nenergy scales. The power of this new formalism is illustrated in the case of\nthe magnetic (RKKY) interaction in graphene.",
        "positive": "Long-range perturbation of helical edge states by nonmagnetic defects in\n  two-dimensional topological insulators: We study the electronic states that are formed due to the tunnel coupling\nbetween helical edge states (HESs) and bound states of nonmagnetic point\ndefects in two-dimensional topological insulators in the general case of broken\naxial spin symmetry. It is found that the coupling of HESs and a single defect\nleads to the formation of composite HESs composed of the bound states and a set\nof the conventional HESs. Their spectral density near the defect has a\nresonance shifted relative to the energy level of the bound state. But of most\nimportance is a long-range perturbation of the HESs around the defect, which is\na cloud consisting of both Kramers partners of conventional edge states.\nTherefore each of the composite HESs contains both the right- and left-moving\nconventional HESs. The amplitude of this perturbation decreases inversely with\nthe distance from the defect. In a system of many defects, this perturbation\nleads to a long-range coupling between bound states of different defects\nmediated by the HESs and causes amazing effects. We study these effects for a\ntwo-defect system where the proposed mechanism of indirect coupling leads to a\nsplitting of the resonances of isolated defects even if the distance between\nthem is very large. As a result an asymmetric structure of two-peak resonance\narises that very unusually changes with the distance between the defects."
    },
    {
        "anchor": "Mesoscopic competition of superconductivity and ferromagnetism:\n  conductance peak statistics in metallic grains: We investigate the competition between superconductivity and ferromagnetism\nin chaotic ultra-small metallic grains in a regime where both phases can\ncoexist. We use an effective Hamiltonian that combines a BCS-like pairing term\nand a ferromagnetic Stoner-like spin exchange term. We study the transport\nproperties of the grain in the Coulomb blockade regime and identify signatures\nof the coexistence between pairing and exchange correlations in the mesoscopic\nfluctuations of the conductance peak spacings and peak heights.",
        "positive": "Quantum Transport in Two-Channel Fractional Quantum Hall Edges: We study the effect of backward scatterings in the tunneling at a point\ncontact between the edges of a second level hierarchical fractional quantum\nHall states. A universal scaling dimension of the tunneling conductance is\nobtained only when both of the edge channels propagate in the same direction.\nIt is shown that the quasiparticle tunneling picture and the electron tunneling\npicture give different scaling behaviors of the conductances, which indicates\nthe existence of a crossover between the two pictures. When the direction of\ntwo edge-channels are opposite, e.g. in the case of MacDonald's edge\nconstruction for the $\\nu=2/3$ state, the phase diagram is divided into two\ndomains giving different temperature dependence of the conductance."
    },
    {
        "anchor": "The Signs of Quantum Dot-Lead Matrix Elements: The Effect on Transport\n  vs. Spectral Properties: A small quantum dot coupled to two external leads is considered. Different\nsigns of the dot-leads coupling matrix elements give rise to qualitatively\ndifferent behavior of physical observables such as the conductance, the phase\nof the transmission amplitude and the differential capacitance of the dot. For\ncertain relative signs the conductance may vanish at values of the gate\npotential, where the spectral density is maximal. Zeroes of the conductance are\nrobust against increasing the dot-lead coupling. They are associated with\nabrupt phase lapses in the transmission phase whose width vanishes as the\nsquare of the temperature. We carefully distinguish between phase lapses of\n$-\\pi$ and phase anti-lapses of $\\pi$.",
        "positive": "Odd integer quantum Hall states with interlayer coherence in twisted\n  bilayer graphene: We report on the quantum Hall effect in two stacked graphene layers rotated\nby 2 degree. The tunneling strength among the layers can be varied from very\nweak to strong via the mechanism of magnetic breakdown when tuning the density.\nOdd-integer quantum Hall physics is not anticipated in the regime of suppressed\ntunneling for balanced layer densities, yet it is observed. We interpret this\nas a signature of Coulomb interaction induced interlayer coherence and Bose\nEinstein condensation of excitons that form at half filling of each layer. A\ndensity imbalance gives rise to reentrant behavior due to a phase transition\nfrom the interlayer coherent state to incompressible behavior caused by\nsimultaneous condensation of both layers in different quantum Hall states. With\nincreasing overall density, magnetic breakdown gains the upper hand. As a\nconsequence of the enhanced interlayer tunneling, the interlayer coherent state\nand the phase transition vanish."
    },
    {
        "anchor": "Simple approach for the two-terminal conductance through interacting\n  clusters: We present a new method for the determination of the two-terminal\ndifferential conductance through an interacting cluster, where one maps the\ninteracting cluster into a non-interacting cluster of $M$ independent sites\n(where $M$ is the number of cluster states with one particle more or less than\nthe ground state of the cluster), with different onsite energy and connected to\nthe leads with renormalized hoppings constants. The onsite energies are\ndetermined from the one-particle (one-hole) excitations of the interacting\ncluster and the hopping terms are given by the overlap between the interacting\n$N$ particle ground state and the one-particle (one-hole) excitations of the\ninteracting cluster with $N$-1 ($N$+1) particles. The conductance is obtained\nfrom the solution of a system of $M$+2 coupled linear equations. We apply this\nmethod to the case of the conductance of spinless fermions through an AB$_2$\nring taking into account nearest neighbors interactions. We discuss the effects\nof interactions on the zero frequency dipped conductance peak characteristic of\nthe non-interacting AB$_2$ ring as well as the consequences of a particle\nnumber jump that occurs as the gate potential is varied.",
        "positive": "Spin injection efficiency at metallic interfaces probed by THz emission\n  spectroscopy: Terahertz (THz) spin-to-charge conversion has become an increasingly\nimportant process for THz pulse generation and as a tool to probe ultrafast\nspin interactions at magnetic interfaces. However, its relation to traditional,\nsteady state, ferromagnetic resonance techniques is poorly understood. Here we\ninvestigate nanometric trilayers of Co/X/Pt (X=Ti, Au or Au0:85W0:15) as a\nfunction of the 'X' layer thickness, where THz emission generated by the\ninverse spin Hall effect is compared to the Gilbert damping of the\nferromagnetic resonance. Through the insertion of the 'X' layer we show that\nthe ultrafast spin current injected in the non-magnetic layer defines a direct\nspin conductance, whereas the Gilbert damping leads to an effective spin\nmixing-conductance of the trilayer. Importantly, we show that these two\nparameters are connected to each other and that spin-memory losses can be\nmodeled via an effective Hamiltonian with Rashba fields. This work highlights\nthat magneto-circuits concepts can be successfully extended to ultrafast\nspintronic devices, as well as enhancing the understanding of spin-to-charge\nconversion processes through the complementarity between ultrafast THz\nspectroscopy and steady state techniques."
    },
    {
        "anchor": "Gate-controlled one-dimensional channel on the topological surface: We investigate the formation of the one-dimensional channels on the\ntopological surface under the gate electrode. The energy dispersion of these\nchannels is almost linear in the momentum with the velocity sensitively\ndepending on the strength of the gate voltage. The energy is also restricted to\nbe positive or negative depending on the strength of the gate voltage.\nConsequently, the local density of states near the gated region has an\nasymmetric structure with respect to zero energy. In the presence of the\nelectron-electron interaction, the correlation effect can be tuned by the gate\nvoltage. We also suggest a tunneling experiment to verify the presence of these\nbound states.",
        "positive": "g-B3N3C: a novel two-dimensional graphite-like material: A novel crystalline structure of hybrid monolayer hexagonal boron nitride\n(BN) and graphene is predicted by means of the first-principles calculations.\nThis material can be derived via boron or nitrogen atoms substituted by carbon\natoms evenly in the graphitic BN with vacancies. The corresponding structure is\nconstructed from a BN hexagonal ring linking an additional carbon atom. The\nunit cell is composed of 7 atoms, 3 of which are boron atoms, 3 are nitrogen\natoms, and one is carbon atom. It behaves a similar space structure as\ngraphene, which is thus coined as g-B3N3C. Two stable topological types\nassociated with the carbon bonds formation, i.e., C-N or C-B bonds, are\nidentified. Interestingly, distinct ground states of each type, depending on\nC-N or C-B bonds, and electronic band gap as well as magnetic properties within\nthis material have been studied systematically. Our work demonstrates practical\nand efficient access to electronic properties of two-dimensional nanostructures\nproviding an approach to tackling open fundamental questions in\nbandgap-engineered devices and spintronics."
    },
    {
        "anchor": "Tunable capacitive inter-dot coupling in a bilayer graphene double\n  quantum dot: We report on a double quantum dot which is formed in a width-modulated etched\nbilayer graphene nanoribbon. A number of lateral graphene gates enable us to\ntune the quantum dot energy levels and the tunneling barriers of the device\nover a wide energy range. Charge stability diagrams and in particular\nindividual triple point pairs allow to study the tunable capacitive inter-dot\ncoupling energy as well as the spectrum of the electronic excited states on a\nnumber of individual triple points. We extract a mutual capacitive inter-dot\ncoupling in the range of 2 - 6 meV and an inter-dot tunnel coupling on the\norder of 1.5 {\\mu}eV.",
        "positive": "Single magnetic adsorbates on s-wave superconductors: In superconductors, magnetic impurities induce a pair-breaking potential for\nCooper pairs, which locally affects the Bogoliubov quasiparticles and gives\nrise to Yu-Shiba-Rusinov (YSR or Shiba, in short) bound states in the density\nof states (DoS). These states carry information on the magnetic coupling\nstrength of the impurity with the superconductor, which determines the\nmany-body ground state properties of the system. Recently, the interest in\nShiba physics was boosted by the prediction of topological superconductivity\nand Majorana modes in magnetically coupled chains and arrays of Shiba\nimpurities. Here, we review the physical insights obtained by scanning\ntunneling microscopy into single magnetic adsorbates on the $s$-wave\nsuperconductor lead (Pb). We explore the tunneling processes into Shiba states,\nshow how magnetic anisotropy affects many-body excitations, and determine the\ncrossing of the many-body groundstate through a quantum phase transition.\nFinally, we discuss the coupling of impurities into dimers and chains and their\nrelation to Majorana physics."
    },
    {
        "anchor": "Tuning edge state localization in graphene nanoribbons by in-plane\n  bending: The electronic properties of graphene are influenced by both geometric\nconfinement and strain. We study the electronic structure of in-plane bent\ngraphene nanoribbons, systems where confinement and strain are combined. To\nunderstand its electronic properties, we develop a tight-binding model that has\na small computational cost and is based on exponentially decaying hopping and\noverlap parameters. Using this model, we show that the edge states in zigzag\ngraphene nanoribbons are sensitive to bending and develop an effective\ndispersion that can be described by a one-dimensional atomic chain model.\nBecause the velocity of the electrons at the edge is proportional to the slope\nof the dispersion, the edge states become gradually delocalized upon increasing\nthe strength of bending.",
        "positive": "Sub-Poissonian shot noise in CoFeB/MgO/CoFeB-based magnetic tunneling\n  junctions: We measured the shot noise in the CoFeB/MgO/CoFeB-based magnetic tunneling\njunctions with a high tunneling magnetoresistance ratio (over 200% at 3 K).\nAlthough the Fano factor in the anti-parallel configuration is close to unity,\nit is observed to be typically 0.91\\pm0.01 in the parallel configuration. It\nindicates the sub-Poissonian process of the electron tunneling in the parallel\nconfiguration due to the relevance of the spin-dependent coherent transport in\nthe low bias regime."
    },
    {
        "anchor": "Field induced phase segregation and collective excitations of a trapped\n  spinor Bose-Einstein condensate: A hydrodynamic description is used to study the zero-temperature properties\nof a trapped spinor Bose-Einstein condensate in the presence of a uniform\nmagnetic field. We show that, in the case of antiferromagnetic spin-spin\ninteraction, the polar and ferromagnetic configurations of the ground state can\ncoexist in the trap. These two phases are spatially segregated in such a way\nthat the polar state occupies the inner part while the ferromagnetic state\noccupies the outer part of the atomic cloud. We also derive a set of coupled\nhydrodynamic equations for the number density and spin density excitations of\nthe system. It is shown that these equations can be analytically solved for the\nsystem in an isotropic harmonic trap and a constant magnetic field. Remarkably,\nthe related low lying excitation spectra are completely determined by the\nsolutions in the region occupied by the polar state. We find that, within the\nThomas-Fermi approximation, the presence of a constant magnetic field does not\nchange the excitation spectra which still possess the similar form of that\nobtained by Stringari.",
        "positive": "The origin of electron-hole asymmetry in graphite: The electron hole asymmetry has been measured in natural graphite using\nmagneto-optical absorption measurements. A splitting is observed for the\ntransitions at both the $K$-point and the $H$-point of the Brillouin zone of\ngraphite where the effect of trigonal warping vanishes. This result is fully\nconsistent with the SWM Hamiltonian providing the free electron kinetic energy\nterms are taken into account. An identical electron-hole asymmetry should be\npresent in graphene."
    },
    {
        "anchor": "Nonlocal Entanglement of 1D Thermal States Induced by Fermion Exchange\n  Statistics: When two identical fermions exchange their positions, their wave function\ngains phase factor $-1$. We show that this distance-independent effect can\ninduce nonlocal entanglement in one-dimensional (1D) electron systems having\nMajorana fermions at the ends. It occurs in the system bulk and has nontrivial\ntemperature dependence. In a system having a single Majorana at each end, the\nnonlocal entanglement has a Bell-state form at zero temperature and decays as\ntemperature increases, vanishing suddenly at certain finite temperature. In a\nsystem having two Majoranas at each end, it is in a cluster-state form and its\nnonlocality is more noticeable at finite temperature. By contrast, thermal\nstates of corresponding 1D spins do not have nonlocal entanglement.",
        "positive": "Exactly solvable Kitaev model in three dimensions: We introduce a spin-1/2 model in three dimensions which is a generalization\nof the well-known Kitaev model on a honeycomb lattice. Following Kitaev, we\nsolve the model exactly by mapping it to a theory of non-interacting fermions\nin the background of a static Z_2 gauge field. The phase diagram consists of a\ngapped phase and a gapless one, similar to the two-dimensional case.\nInterestingly, unlike in the two-dimensional model, in the gapless phase the\ngap vanishes on a contour in the k space. Furthermore, we show that the flux\nexcitations of the gauge field, due to some local constraints, form loop like\nstructures; such loops exist on a lattice formed by the plaquettes in the\noriginal lattice and is topologically equivalent to the pyrochlore lattice.\nFinally, we derive a low-energy effective Hamiltonian that can be used to study\nthe properties of the excitations in the gapped phase."
    },
    {
        "anchor": "Spin dephasing in Silicon Germanium nanowires: We study spin polarized transport in silicon germanium nanowires using a\nsemiclassical monte carlo approach. Spin depolarization in the channel is\ncaused due to D'yakonov-Perel (DP) relaxation associated with Rashba spin orbit\ncoupling and due to Elliott- Yafet (EY) relaxation. We investigate the\ndependence of spin dephasing on germanium mole fraction in silicon germanium\nnanowires. The spin dephasing lengths decrease with an increase in the\ngermanium mole fraction. We also find that the temperature has a strong\ninfluence on the dephasing rate and spin relaxation lengths increase with\ndecrease in temperature. The ensemble averaged spin components and the steady\nstate distribution of spin components vary with initial polarization.",
        "positive": "Tunable Kondo effect in double quantum dots coupled to ferromagnetic\n  contacts: We investigate the effects induced by spin polarization in the contacts\nattached to a serial double quantum dot. The polarization generates effective\nmagnetic fields and suppresses the Kondo effect in each dot. The super-exchange\ninteraction ($J_{\\mathrm{AFM}}$), tuned by the inter-dot tunnelling rate $t$,\ncan be used to compensate the effective fields and restore the Kondo resonance\nwhen the contact polarizations are aligned. As a consequence, the direction of\nthe spin conductance can be controlled and even reversed using electrostatic\ngates alone. Furthermore, we study the associated two-impurity Kondo model and\nshow that a ferromagnetic exchange coupling ($J_{\\mathrm{FM}}$) leads to an\neffective spin-1 exchange-anisotropic Kondo model which exhibits a quantum\nphase transition in the presence of partially polarized contacts."
    },
    {
        "anchor": "System size dependent topological zero modes in coupled topolectrical\n  chains: In this paper, we demonstrate the emergence and disappearance of topological\nzero modes (TZMs) in a coupled topolectrical (TE) circuit lattice.\nSpecifically, we consider non-Hermitian TE chains in which TZMs do not occur in\nthe individual uncoupled chains, but emerge when these chains are coupled by\ninter-chain capacitors. The coupled system hosts TZMs which show size-dependent\nbehaviours and vanish beyond a certain critical size. In addition, the\nemergence or disappearance of the TZMs in the open boundary condition (OBC)\nspectra for a given size of the coupled system can be controlled by modulating\nthe signs of its inverse decay length. Analytically, trivial and non-trivial\nphases of the coupled system can be distinguished by the differing ranks of\ntheir corresponding Laplacian matrix. The TE circuit framework enables the\nphysical detection of the TZMs via electrical impedance measurements. Our work\nestablishes the conditions for inducing TZMs and modulating their behavior in\ncoupled TE chains.",
        "positive": "Many-Body Effects and Optical Properties of Single- and Double Layer\n  $\u03b1$-$\\mathcal{T}_3$ Lattices: An extensive analytical and numerical investigation has been carried out to\nexamine the role played by many-body effects on various\n$\\alpha$-$\\mathcal{T}_3$ materials under an off-resonance optical dressing\nfield. Additionally, we explore its dependence on the hopping parameter\n$\\alpha$ as well as the electron-light coupling strength $\\lambda_0$. The\nobtained dressed states due to mutual interaction between Dirac electrons and\nincident light are shown to demonstrate rather different electronic and optical\nproperties in comparison with those in the absence of incident light.\nSpecifically, various collective transport and optical properties of these\nelectron dressed states are discussed in detail and compared for both single-\nand double layer $\\alpha$-$\\mathcal{T}_3$ lattices. All of these novel\nproperties are due to the presence of a middle flat band and the interband\ntransitions between it and an upper conduction band. Also, coupled plasmon\ndispersions for interacting double layer $\\alpha$-$\\mathcal{T}_3$ lattices are\ncalculated, revealing a lower acoustic-like plasmon branch with tunable group\nvelocity determined by both the layer separation and Fermi energy of each\nlayer. Finally, a many-body theory is presented within the random-phase\napproximation for calculating the optical absorbance of doped multi-layered\n$\\alpha$-$\\mathcal{T}_3$ lattices in a linearly-polarized light field. We\nanticipate that the discoveries reported here could impact the design of the\nnext-generation nano-optical and nano-plasmonic devices."
    },
    {
        "anchor": "Weak antilocalization in Cd3As2 thin films: Recently, it has been theoretically predicted that Cd3As2 is a three\ndimensional Dirac material, a new topological phase discovered after\ntopological insulators, which exhibits a linear energy dispersion in the bulk\nwith massless Dirac fermions. Here, we report on the low-temperature\nmagnetoresistance measurements on a ~50nm-thick Cd3As2 film. The weak\nantilocalization under perpendicular magnetic field is discussed based on the\ntwo-dimensional Hikami-Larkin-Nagaoka (HLN) theory. The electron-electron\ninteraction is addressed as the source of the dephasing based on the\ntemperature-dependent scaling behavior. The weak antilocalization can be also\nobserved while the magnetic field is parallel to the electric field due to the\nstrong interaction between the different conductance channels in this\nquasi-two-dimensional film.",
        "positive": "Coulomb Drag of Massless Fermions in Graphene: Using a novel structure, consisting of two, independently contacted graphene\nsingle layers separated by an ultra-thin dielectric, we experimentally measure\nthe Coulomb drag of massless fermions in graphene. At temperatures higher than\n50 K, the Coulomb drag follows a temperature and carrier density dependence\nconsistent with the Fermi liquid regime. As the temperature is reduced, the\nCoulomb drag exhibits giant fluctuations with an increasing amplitude, thanks\nto the interplay between coherent transport in the graphene layer and\ninteraction between the two layers."
    },
    {
        "anchor": "Hole spin relaxation in bilayer WSe$_2$: We investigate the hole spin relaxation due to the Rashba spin-orbit coupling\ninduced by an external perpendicular electric field in bilayer WSe$_2$. The\nRashba spin-orbit coupling coefficients in bilayer WSe$_2$ are constructed from\nthe corresponding monolayer ones. In contrast to monolayer WSe$_2$, the\nout-of-plane component of the bilayer Rashba spin-orbit coupling acts as a\nZeeman-like field with opposite directions but identical values in the two\nvalleys. For in-plane spins, this Zeeman-like field, together with the\nintervalley hole-phonon scattering, opens an intervalley spin relaxation\nchannel, which is found to dominate the in-plane spin relaxation in bilayer\nWSe$_2$ even at low temperature. For out-of-plane spins, this Zeeman-like field\nis superimposed by the identical Hartree-Fock effective magnetic fields in the\ntwo valleys, and hence different total effective magnetic fields between two\nvalleys are obtained. Owing to the large difference of the total fields at\nlarge spin polarization, different out-of-plane spin relaxation times in the\ntwo valleys are obtained when the intervalley hole-phonon scattering is weak at\nlow temperature and low hole density. This difference in the spin relaxation\ntimes can be suppressed by enhancing the intervalley hole-phonon scattering\nthrough increasing temperature or hole density. Moreover, at large spin\npolarization and low temperature, due to the weak intravalley hole-phonon\nscattering but relatively strong hole-hole Coulomb scattering, the fast spin\nprecessions are found to result in a quasi hot-hole Fermi distribution\ncharacterized by an effective hot-hole temperature larger than the temperature,\nwhich also enhances the intervalley scattering. During this process, it is\ninteresting to discover that the initially equal hole densities in the two\nvalleys are broken in the temporal evolution, and a valley polarization is\nbuilt up. ....",
        "positive": "Tensile strain induced brightening of momentum forbidden dark exciton in\n  WS$_2$: Transition-metal dichalcogenides (TMDs) host tightly bound quasi-particles\ncalled excitons. Based on spin and momentum selection rules, these excitons can\nbe either optically bright or dark. In tungsten-based TMDs, momentum-forbidden\ndark exciton is the energy ground state and therefore it strongly affect the\nemission properties. In this work, we brighten the momentum forbidden dark\nexciton by placing WS$_2$ on top of nanotextured substrates which put the\nWS$_2$ layer under tensile strain, modifying electronic bandstructure. This\nenables phonon assisted scattering of exciton between momentum valleys, thereby\nbrightening momentum forbidden dark excitons. Our results will pave the way to\ndesign ultrasensitive strain sensing devices based on TMDs."
    },
    {
        "anchor": "Semiclassical Time Evolution of the Holes from Luttinger Hamiltonian: We study the semi-classical motion of holes by exact numerical solution of\nthe Luttinger model. The trajectories obtained for the heavy and light holes\nagree well with the higher order corrections to the abelian and the non-abelian\nadiabatic theories in Ref. [1] [S. Murakami et al., Science 301, 1378(2003)],\nrespectively. It is found that the hole trajectories contain rapid oscillations\nreminiscent of the \"Zitterbewegung\" of relativistic electrons. We also comment\non the non-conservation of helicity of the light holes.",
        "positive": "Large Conductance Variations in a Mechanosensitive Single-Molecule\n  Junction: The appealing feature of molecular electronics is the possibility of\nexploiting functionality built within a single molecule. This functionality can\nbe employed, for example, for sensing or switching purposes. Thus, ideally, the\nassociated conductance changes should be sizable upon application of external\nstimuli. Here, we show that a molecular spring can be mechanically compressed\nor elongated to tune its conductance by up to an order of magnitude by\ncontrolling the quantum interference between electronic pathways. Oscillations\nin the conductance occur when the stress built up in the molecule is high\nenough to allow the anchoring groups to move along the surface in a\nstick-slip-like fashion. The mechanical control of quantum interference effects\nand the resulting large change in molecular conductance open the door for\napplications in, e.g., a minute mechanosensitive sensing device functional at\nroom temperature."
    },
    {
        "anchor": "Aperiodic Weak Topological Superconductors: Weak topological phases are usually described in terms of protection by the\nlattice translation symmetry. Their characterization explicitly relies on\nperiodicity since weak invariants are expressed in terms of the momentum-space\ntorus. We prove the compatibility of weak topological superconductors with\naperiodic systems, such as quasicrystals. We go beyond usual descriptions of\nweak topological phases and introduce a novel, real-space formulation of the\nweak invariant, based on the Clifford pseudospectrum. A non-trivial value of\nthis index implies a non-trivial bulk phase, which is robust against disorder\nand hosts localized zero-energy modes at the edge. Our recipe for determining\nthe weak invariant is directly applicable to any finite-sized system, including\ndisordered lattice models. This direct method enables a quantitative analysis\nof the level of disorder the topological protection can withstand.",
        "positive": "Heat dissipation mechanisms in hybrid superconductor-semiconductor\n  devices revealed by Joule spectroscopy: Understanding heating and cooling mechanisms in mesoscopic\nsuperconductor-semiconductor hybrid devices is crucial for their application in\nquantum technologies. Owing to the poor thermal conductivity of typical\ndevices, heating effects can drive superconducting-to-normal phase transitions\neven at low applied bias, observed as sharp conductance dips through the loss\nof Andreev excess currents. Tracking such dips across magnetic field, cryostat\ntemperature, and applied microwave power, which constitutes Joule spectroscopy,\nallows to uncover the underlying cooling bottlenecks in different parts of a\ndevice. By applying this technique, we analyze heat dissipation in devices\nbased on full-shell InAs-Al nanowires and reveal that superconducting islands\nare strongly susceptible to heating as their cooling is limited by the rather\ninefficient electron-phonon coupling, as opposed to grounded superconductors\nthat primarily cool by quasiparticle diffusion. Our measurements indicate that\npowers as low as 50-150 pW are able to fully suprpress the superconductivity of\nan island. Finally, we show that applied microwaves lead to similar heating\neffects as DC signals, and explore the interplay of the microwave frequency and\nthe effective electron-phonon relaxation time."
    },
    {
        "anchor": "Numerical renormalization group study of two-channel three-impurity\n  triangular clusters: We study triangular clusters of three spin-1/2 Kondo or Anderson impurities\nthat are coupled to two conduction leads. In the case of Kondo impurities, the\nmodel takes the form of an antiferromagnetic Heisenberg ring with Kondo-like\nexchange coupling to continuum electrons. We show that this model exhibits many\ntypes of the behavior found in various simpler one and two-impurity models,\nthereby enabling the study of crossovers between a number of Fermi-liquid (FL)\nand non-Fermi-liquid (NFL) fixed points. In particular, we explore a direct\ncrossover between the two-impurity Kondo-model NFL fixed point and the\ntwo-channel Kondo-model NFL fixed point. We show that the concept of the\ntwo-stage Kondo effect applies even in the case when the first-stage Kondo\nstate is of NFL type. In the case of Anderson impurities, we consider the\ntransport properties of three coupled quantum dots. This class of models\nincludes as limiting cases the familiar serial double quantum dot and triple\nquantum dot nanostructures. By extracting the quasiparticle scattering phase\nshifts, we compute the low-temperature conductance as a function of the\ninter-impurity tunneling-coupling. We point out that due to the existence of\nexponentially low temperature scales, there is a parameter range where the\nstable \"zero-temperature\" fixed point is essentially never reached (not even in\nnumerical renormalization group calculations). The \"zero-temperature\"\nconductance is then of no interest and it may only be meaningful to compute the\nconductance at finite temperature. This illustrates the perils of studying the\nconductance in the ground state and considering thermal fluctuations only as a\nsmall correction.",
        "positive": "Excitons in Electrostatic Traps: We consider in-plane electrostatic traps for indirect excitons in coupled\nquantum wells, where the traps are formed by a laterally modulated gate\nvoltage. An intrinsic obstacle for exciton confinement in electrostatic traps\nis an in-plane electric field that can lead to exciton dissociation. We propose\na design to suppress the in-plane electric field and, at the same time, to\neffectively confine excitons in the electrostatic traps. We present\ncalculations for various classes of electrostatic traps and experimental proof\nof principle for trapping of indirect excitons in electrostatic traps."
    },
    {
        "anchor": "Transport on a topological insulator surface with a time-dependent\n  magnetic barrier: We study transport across a time-dependent magnetic barrier present on the\nsurface of a three-dimensional topological insulator. We show that such a\nbarrier can be implemented for Dirac electrons on the surface of a\nthree-dimensional topological insulator by a combination of a proximate\nmagnetic material and linearly polarized external radiation. We find that the\nconductance of the system can be tuned by varying the frequency and amplitude\nof the radiation and the energy of an electron incident on the barrier\nproviding us optical control on the conductance of such junctions. We first\nstudy a $\\delta$-function barrier which shows a number of interesting features\nsuch as sharp peaks and dips in the transmission at certain angles of\nincidence. Approximate methods for studying the limits of small and large\nfrequencies are presented. We then study a barrier with a finite width. This\ngives rise to some new features which are not present for a $\\delta$-function\nbarrier, such as resonances in the conductance at certain values of the system\nparameters. We present a perturbation theory for studying the limit of large\ndriving amplitude and use this to understand the resonances. Finally, we use a\nsemiclassical approach to study transmission across a time-dependent barrier\nand show how this can qualitatively explain some of the results found in the\nearlier analysis. We discuss experiments which can test our theory.",
        "positive": "Comment on \"Magnetoresistance and differential conductance in\n  mutliwalled carbon nanotubes\": Jeong-O Lee et al. [Phy. Rev. B, 61, R16 362 (2000)] reported\nmagnetoresistance and differential conductance measurements of multiwalled\ncarbon nanotubes. The observed aperiodic conductance fluctuations and the\nnegative magnetoresistance was interpreted to originate exclusively from\nchanges in the density of states at the Fermi energy. We show that this\ninterpretation is questionable and not supported by their measurements."
    },
    {
        "anchor": "Magnetic hallmarks of viscous electron flow in graphene: We propose a protocol to identify spatial hallmarks of viscous electron flow\nin graphene and other two-dimensional viscous electron fluids. We predict that\nthe profile of the magnetic field generated by hydrodynamic electron currents\nflowing in confined geometries displays unambiguous features linked to\nwhirlpools and backflow near current injectors. We also show that the same\nprofile sheds light on the nature of the boundary conditions describing\nfriction exerted on the electron fluid by the edges of the sample. Our\npredictions are within reach of vector magnetometry based on nitrogen-vacancy\ncenters embedded in a diamond slab mounted onto a graphene layer.",
        "positive": "Vortex clusters in a stirred polariton condensate: The response of superfluids to the external rotation, evidenced by emergence\nof quantised vortices, distinguishes them from conventional fluids. In this\nwork, we demonstrate that the number of vortices in a stirred polariton\ncondensate depends on the characteristic size of the employed rotating\npotential induced by the nonresonant laser excitation. For smaller sizes, a\nsingle vortex with a topological charge of +-1 corresponding to the stirring\ndirection is formed. However, for larger optical traps, clusters of two or\nthree co-rotating vortices appear in the narrow range of GHz stirring speed."
    },
    {
        "anchor": "Quasi ballistic magnetization reversal: We demonstrate a quasi ballistic switching of the magnetization in a\nmicroscopic mag-neto resistive memory cell. By means of time resolved magneto\ntransport we follow the large angle precession of the free layer magnetization\nof a spin valve cell upon applica-tion of transverse magnetic field pulses.\nStopping the field pulse after a 180 degree precession rotation leads to\nmagnetization reversal with reversal times as short as 165 ps. This switching\nmode represents the fundamental ultra fast limit of field induced magnetization\nreversal.",
        "positive": "Stepwise quantum phonon pumping in plasmon-enhanced Raman scattering: Plasmon-enhanced Raman scattering (PERS) becomes nonlinear when phonon\npumping and phonon-stimulated scattering come into play. It is fundamental to\nthe understanding of PERS and its photobleaching behavior. By quantization of\nthe molecular vibration coherent state into phonon number states, we\ntheoretically predict a stepwise dependence of PERS intensity on laser power.\nExperimental evidence is presented by measuring a monolayer of malachite green\nisothiocyanate molecules sandwiched in individual gold nanosphere-plane\nantennas, under radially polarized laser excitation of sub-microWatt powers."
    },
    {
        "anchor": "Moir\u00e9 phonons in the twisted bilayer graphene: We study the in-plane acoustic phonons in twisted bilayer graphenes using the\neffective continuum approach. We calculate the phonon modes by solving the\ncontinuum equation of motion for infinitesimal vibration around the static\nrelaxed state with triangular domain structure. We find that the moir\\'{e}\ninterlayer potential only affects the in-plane asymmetric modes, where the\noriginal linear dispersion is broken down into miniphonon bands separated by\ngaps, while the in-plane symmetric modes with their linear dispersion are\nhardly affected. The phonon wave functions of asymmetric modes are regarded as\ncollective vibrations of the domain-wall network, and the low-energy phonon\nband structure can be qualitatively described by an effective moir\\'{e}-scale\nlattice model.",
        "positive": "Generalization of Laughlin's Theory for the Fractional Quantum Hall\n  Effect: Motivated by the quasiparticle wavefunction in the composite fermion (CF)\ntheory for fractional quantum Hall filling factor $\\nu = 1/m$, I consider a\nsuitable quasiparticle operator in differential form, as a modified form of\nLaughlin's quasiparticle operator, that reproduces quasiparticle wave function\nas predicted in the CF theory. I further consider the conjugate of this\noperator as quasihole operator for obtaining a novel quasihole wave function\nfor $1/m$ state. Each of these wave functions is interpreted as expelled\nelectron into a different Hilbert subspace from the original Hilbert space of\nLaughlin condensate while still maintaining its correlation (although changed)\nwith the electrons in the condensate such that the expelled electron behaves as\na CF with respect to the electrons in the condensate. With this interpretation,\nI show that the ground state wavefunctions for general states at filling\nfractions $\\nu_{n,m}^{\\pm} = n/[n(m\\mp 1)\\pm 1]$, respectively, can be\nconstructed as coherent superposition of $n$ coupled Laughlin condensates and\ntheir conjugates, formed at different Hilbert subspaces. The corresponding wave\nfunctions, specially surprising for $\\nu_{n,m}^{-}$ sequence of states, are\nidentical with those proposed in the theory of noninteracting CFs. The states\nwhich were considered as fractional quantum Hall effect of interacting CFs, can\nalso be treated in the same footing as for the prominent sequences of states\ndescribing as the coupled condensates among which one is a non-Laughlin\ncondensate in a different Hilbert subspace. Further, I predict that the half\nfilling of the lowest Landau level is a quantum critical point for phase\ntransitions between two topologically distinct phases each corresponding to a\nfamily of states."
    },
    {
        "anchor": "Purely electronic nanometallic ReRAM: Resistance switching random access memory (ReRAM), with the ability to\nrepeatedly modulate electrical resistance, has been highlighted as a feasible\nhigh-density memory with the potential to replace negative-AND (NAND) flash\nmemory. Such resistance modulation usually involves ion migration and filament\nformation, which usually lead to relatively low device reliability and yield.\nResistance switching can also come from an entirely electronic origin, as in\nnanometallic memory, by electron trapping and detrapping. Recent research has\nrevealed additional merits of its mechanism, which entails smart, atomic-sized\nfloating gates that can be easily engineered in amorphous Si, oxides, and\nnitrides. This article addresses the basic ideas of nanometallic ReRAM, which\nmay also be a contender for analogue computing and non-von Neumann-type\ncomputation.",
        "positive": "Comments on \"Fractional Quantum Hall Effect of Composite Fermions, W.\n  Pan, et al, Phys. Rev. Lett. 90, 016801 (2003): It is shown that even number of flux quanta are not attached to one electron.\nThe magnetic flux is not detached from the currents and the E and H separation\ndoes not occur in the quantum Hall effect, where E is the electric vector and H\nis the magnetic vector of the electro- magnetic field. We show how a sequence\ncan agree with the experimental data and be wrong also. It is not possible for\nthree electrons to carry 8 flux quanta. There is no temperature in the\ncomposite fermion formulas. It may be perfectly acceptable to modify the Biot\nand Savart's law which is the fundamental law used for making electromagnets\nbut the CFs are internally inconsistent and hence are not suitable as part of\nfundamentally correct physics."
    },
    {
        "anchor": "Carrier trapping in a quantum dash: optical signatures: We theoretically study the optical properties and the electronic structure of\nhighly elongated quantum dots (quantum dashes) and show how geometrical\nfluctuations affect the excitonic spec- trum of the system. The dependence of\nthe absorption intensities on the geometrical properties (depth and length) of\nthe trapping center in a quantum dash is analyzed and the dependence of the\ndegree of the linear polarization on these geometrical parameters is studied.",
        "positive": "Dynamic polarization of electron spins in indirect band gap\n  (In,Al)As/AlAs quantum dots in weak magnetic field: experiment and theory: A novel spin orientation mechanism - dynamic electron spin polarization has\nbeen recently suggested in Phys. Rev. Lett. $\\mathbf{125}$, 156801 (2020). It\ntakes place for unpolarized optical excitation in weak magnetic fields of the\norder of a few millitesla. In this paper we demonstrate experimentally and\ntheoretically that the dynamic electron spin polarization degree changes sign\nas a function of time, strength of the applied magnetic field and its\ndirection. The studies are performed on indirect band-gap (In,Al)As/AlAs\nquantum dots and their results are explained in the framework of a theoretical\nmodel developed for our experimental setting."
    },
    {
        "anchor": "One-step fabrication of metal nanostructures by high-throughput\n  imprinting: Direct nanoimprinting provides a simple and high-throughput route for\nproducing uniform nanopatterns at great precision and at low costs. However,\napplying this technique to crystalline metals has been considered as impossible\ndue to intrinsic limitation from grain size effect. Here we demonstrate direct\nsuperplastic nanoimprinting (SPNI) of crystalline metals well below their\nmelting temperatures (Tm), generating ordered nanowire arrays with aspect ratio\nup to ~2000. Our investigations of replicating metal hierarchical\nnanostructures show the capability of imprinting features as small as 8 nm, far\nsmaller than the grain size of bulk metals. Most surprisingly, the prepared\nmetal hierarchical nanostructures were found possessing perfect monocrystalline\nstructures. These findings indicate that nanoimprinting of crystalline metals\nbelow Tm might be from lattice diffusion. SPNI as a one-step and highly\ncontrolled high-throughput fabrication method, could facilitate the\napplications of metal nanostructures in bio-sensing, diagnostic imaging,\ncatalysis, food industry and environmental conservation.",
        "positive": "Isolation of Single Donors in ZnO: The shallow donor in zinc oxide (ZnO) is a promising semiconductor spin qubit\nwith optical access. Single indium donors are isolated in a commercial ZnO\nsubstrate using plasma focused ion beam (PFIB) milling. Quantum emitters are\nidentified optically by spatial and frequency filtering. The indium donor\nassignment is based on the optical bound exciton transition energy and magnetic\ndependence. The single donor emission is intensity and frequency stable with a\ntransition linewidth less than twice the lifetime limit. The isolation of\noptically stable single donors post-FIB fabrication is promising for optical\ndevice integration required for scalable quantum technologies based on single\ndonors in direct band gap semiconductors."
    },
    {
        "anchor": "Low energy Ne ion beam induced-modifications of magnetic properties in\n  MnAs thin films: Investigations of the complex behavior of the magnetization of manganese\narsenide thin films due to defects induced by irradiation of slow heavy ions\nare presented. In addition to the thermal hysteresis suppression already\nhighlighted in M. Trassinelli et al., Appl. Phys. Lett. 104, 081906 (2014), we\nreport here on new local magnetic features recorded by a magnetic force\nmicroscope at different temperatures close to the characteristic sample phase\ntransition. Complementary measurements of the global magnetization measurements\nin different conditions (applied magnetic field and temperatures) enable to\ncomplete the film characterization. The obtained results suggest that the ion\nbombardment produces regions where the local mechanical constraints are\nsignificantly different from the average, promoting the local presence of\nmagneto-structural phases far from the equilibrium. These regions could be\nresponsible for the thermal hysteresis suppression previously reported,\nirradiation-induced defects acting as seeds in the phase transition.",
        "positive": "Magneto-transmission of multi-layer epitaxial graphene and bulk\n  graphite: A comparison: Magneto-transmission of a thin layer of bulk graphite is compared with\nspectra taken on multilayer epitaxial graphene prepared by thermal\ndecomposition of a SiC crystal. We focus on the spectral features evolving as\n\\sqrt{B}, which are evidence for the presence of Dirac fermions in both\nmaterials. Whereas the results on multi-layer epitaxial graphene can be\ninterpreted within the model of 2D Dirac fermions, the data obtained on bulk\ngraphite can only be explained taking into account the 3D nature of graphite,\ne.g. by using the standard Slonczewski-Weiss-McClure model."
    },
    {
        "anchor": "Miniaturizing neural networks for charge state autotuning in quantum\n  dots: A key challenge in scaling quantum computers is the calibration and control\nof multiple qubits. In solid-state quantum dots, the gate voltages required to\nstabilize quantized charges are unique for each individual qubit, resulting in\na high-dimensional control parameter space that must be tuned automatically.\nMachine learning techniques are capable of processing high-dimensional data -\nprovided that an appropriate training set is available - and have been\nsuccessfully used for autotuning in the past. In this paper, we develop\nextremely small feed-forward neural networks that can be used to detect\ncharge-state transitions in quantum dot stability diagrams. We demonstrate that\nthese neural networks can be trained on synthetic data produced by computer\nsimulations, and robustly transferred to the task of tuning an experimental\ndevice into a desired charge state. The neural networks required for this task\nare sufficiently small as to enable an implementation in existing memristor\ncrossbar arrays in the near future. This opens up the possibility of\nminiaturizing powerful control elements on low-power hardware, a significant\nstep towards on-chip autotuning in future quantum dot computers.",
        "positive": "Impact of Dimensionality on PN Junctions: Low dimensional material systems provide a unique set of properties useful\nfor solid-state devices. The building block of these devices is the PN\njunction. In this work, we present a dramatic difference in the electrostatics\nof PN junctions in lower dimensional systems, as against the well understood\nthree dimensional systems. Reducing the dimensionality increases the fringing\nfields and depletion width significantly. We propose a novel method to derive\nanalytic equations in 2D and 1D that considers the impact of neutral regions.\nThe analytical results show an excellent match with both the experimental\nmeasurements and numerical simulations. The square root dependence of the\ndepletion width on the ratio of dielectric constant and doping in 3D changes to\na linear and exponential dependence for 2D and 1D respectively. This higher\nsensitivity of 1D PN junctions to its control parameters can be used towards\nnew sensors."
    },
    {
        "anchor": "Theory of superconductor-insulator transition in single Josephson\n  junctions: A non-band theory is developed to describe the superconductor-insulator (SI)\ntranstition in resistively shunted, single Josephson junctions. The $I-V$\ncharacteristic is formulated by a Landauer-like formula and evaluated by the\npath-integral transfer-matrix method. The result is consistent with the recent\nexperiments at around 80 $mK$. However, the insulator phase shrinks with\ndecreasing temperature indicating that the single Josephson junction becomes\nall superconducting at absolute zero temperature, as long as dissipation is\npresent.",
        "positive": "Nonlinear Photoluminescence Properties of Trions in Hole-doped\n  Single-walled Carbon Nanotubes: We studied the excitation density dependence of photoluminescence (PL)\nspectra of excitons and trions (charged excitons) in hole-doped single-walled\ncarbon nanotubes. We found that the PL intensity of trions exhibited a strong\nnonlinear saturation behavior as the excitation density increased, whereas that\nof excitons exhibited a weak sublinear behavior. The strong PL saturation of\ntrions is attributed to depletion of doped holes that are captured by excitons\nin the formation processes. Moreover, the effective radiative lifetime of a\ntrion was evaluated to be approximately 20 ns."
    },
    {
        "anchor": "Non-conventional topological band properties and gapless helical edge\n  states in elastic phononic waveguides with Kekul\u00e9 distortion: This study investigates the topological behavior of a continuous elastic\nphononic structure characterized by a 3-term Kekul\\'e distortion. The elastic\nwaveguide consists of a hexagonal unit cell whose geometric dimensions are\nintentionally perturbed according to a generalized Kekul\\'e scheme. The\nresulting structure exhibits an effective Hamiltonian that resembles a quantum\nspin Hall system, hence suggesting that the waveguide can support helical\ntopological edge states. Using first-principles calculations, we show the\nexistence of nondegenerate pseudospin states and a very peculiar 6-lobe\npseudospin texture and Berry curvature pattern. Important insights are also\nprovided concerning the topological states in the Kekul\\'e lattice, so far\nconsidered indistinguishable, and their critical role in enabling unique\ngapless edge states, typically not achievable in phononic systems.",
        "positive": "Anomalous Characteristics of the Generation - Recombination Noise in\n  Quasi-One-Dimensional Van der Waals Nanoribbons: We describe the low-frequency current fluctuations, i.e. electronic noise, in\nquasi-one-dimensional ZrTe3 van der Waals nanoribbons, which have recently\nattracted attention owing to their extraordinary high current carrying\ncapacity. Whereas the low-frequency noise spectral density reveals 1/f behavior\nnear room temperature, it is dominated by the Lorentzian bulges of the\ngeneration - recombination noise at low temperatures (f is the frequency).\nUnexpectedly, the corner frequency of the observed Lorentzian peaks shows\nstrong sensitivity to the applied source - drain bias. This dependence on\nelectric field can be explained by the Frenkel-Poole effect in the scenario\nwhere the voltage drop happens predominantly on the defects, which block the\nquasi-1D conduction channels. We also have found that the activation energy of\nthe characteristic frequencies of the G-R noise in quasi-1D ZrTe3 is defined\nprimarily by the temperature dependence of the capture cross-section of the\ndefects rather than by their energy position. These results are important for\nthe application of quasi-1D van der Waals materials in ultimately downscaled\nelectronics."
    },
    {
        "anchor": "\"Ping-pong\" electron transfer. I. First reflection of the Loschmidt echo: Quantum dynamics of the electron wave function on one-dimensional lattice is\nconsidered. The lattice consists of $N$ equal sites and one impurity site. The\nimpurity site differs from other sites by the on-site electron energy $E$ and\nthe hopping integral $C$. The wave function is located on the impurity site at\n$t = 0$. The wave packet is formed which travels along the lattice, and\nreflects from its end. Reflections happen many times (Loschmidt echo) and this\nphenomenon is considered in the second part of the paper. Analytical\nexpressions for the wave packet front propagation at different values $E$ and\n$C$ are derived, and they are in excellent agreement with the numerical\nsimulation. The obtained results can help in interpretation of recent\nexperiments on highly efficient charge transport in synthetic olygonucleotides.",
        "positive": "Observation of novel topological states in hyperbolic lattices: The discovery of novel topological states has served as a major branch in\nphysics and material science. However, to date, most of the established\ntopological states of matter have been employed in Euclidean systems, where the\ninterplay between unique geometrical characteristics of curved spaces and\nexotic topological phases is less explored, especially on the experimental\nperspective. Recently, the experimental realization of the hyperbolic lattice,\nwhich is the regular tessellation in non-Euclidean spaces with a constant\nnegative curvature, has attracted much attention in the field of simulating\nexotic phenomena from quantum physics in curved spaces to the general\nrelativity. The question is whether there are novel topological states in such\na non-Euclidean system without analogues in Euclidean spaces. Here, we\ndemonstrate both in theory and experiment that novel topological states\npossessing unique properties compared with their Euclidean counterparts can\nexist in engineered hyperbolic lattices. Specially, based on the extended\nHaldane model, the boundary-dominated first-order Chern edge state with a\nnontrivial real-space Chern number is achieved, and the associated one-way\npropagation is proven. Furthermore, we show that fractal-like midgap\nhigher-order zero modes appear in deformed hyperbolic lattices, where the\nnumber of zero modes increases exponentially with the increase of lattice size.\nThese novel topological states are observed in designed hyperbolic circuit\nnetworks by measuring site-resolved impendence responses and dynamics of\nvoltage packets. Our findings suggest a novel platform to study topological\nphases beyond Euclidean space and may have potential applications in the field\nof designing high-efficient topological devices, such as topological lasers,\nwith extremely fewer trivial regions."
    },
    {
        "anchor": "Two exact properties of the perturbative expansion for the\n  two-dimensional electron liquid with Rashba or Dresselhaus spin-orbit\n  coupling: We have identified two useful exact properties of the perturbative expansion\nfor the case of a two-dimensional electron liquid with Rashba or Dresselhaus\nspin-orbit interaction and in the absence of magnetic field. The results allow\nus to draw interesting conclusions regarding the dependence of the exchange and\ncorrelation energy and of the quasiparticle properties on the strength of the\nspin-orbit coupling which are valid to all orders in the electron-electron\ninteraction.",
        "positive": "Spectroscopy of vibrational modes in metal nanoshells: We study the spectrum of vibrational modes in metal nanoparticles with a\ndielectric core. Vibrational modes are excited by the rapid heating of the\nparticle lattice that takes place after laser excitation, and can be monitored\nby means of pump-probe spectroscopy as coherent oscillations of transient\noptical spectra. In nanoshells, the presence of two metal surfaces results in a\nsubstantially different energy spectrum of acoustic vibrations than for solid\nparticles. We calculated the energy spectrum as well as the damping of\nnanoshell vibrational modes. The oscillator strength of fundamental breathing\nmode is larger than that in solid nanoparticles. At the same time, in very thin\nnanoshells, the fundamental mode is overdamped due to instantaneous energy\ntransfer to the surrounding medium."
    },
    {
        "anchor": "Strip plasmons in a two-dimensional electron gas with grounded\n  electrodes: Plasmons in two-dimensional electron gas (2DEG) strips with grounded\nelectrodes (a gate or side contacts) are investigated. We consider two systems:\n(a) the 2DEG strip with a highly conducting gate and (b) the 2DEG strip with\nsemi-infinite highly conducting side contacts. The systems are described by\nhydrodynamic equations coupled with the Poisson equation. Dispersion relations\nand ac electric potential distributions are obtained. We find the plasmon modes\nwhose potential distributions, and hence electron density, are localized to the\nedges of the strip when the wave number of plasmons in the direction parallel\nto the strip is large. Frequencies of these strip modes are lower than those of\ninfinite two-dimensional plasmons. The presence of grounded electrode(s)\nsignificantly modifies the plasmon dispersion relations.",
        "positive": "Criticisms on and Comparison of Experimental Channel Backscattering\n  Extraction Methods: In this paper we critically review and compare experimental methods, based on\nthe Lundstrom model, to extract the channel backscattering ratio in nano\nMOSFETs. Basically two experimental methods are currently used, the most common\nof them is based on the measurement of the saturation drain current at\ndifferent temperatures. We show that this method is affected by very poor\nassumptions and that the extracted backscattering ratio strongly underestimates\nits actual value posing particular attention to the backscattering actually\nextracted in nano devices. The second method is based on the direct measurement\nof the inversion charge by CV characteristics and gets closer to the physics of\nthe backscattering model. We show, through measurements in high mobility\np-germanium devices, how the temperature based method gives the same result of\nthe CV based method once that its approximations are removed. Moreover we show\nthat the CV based method uses a number of approximations which are partially\ninconsistent with the model. In particular we show, with the aid of 2D quantum\ncorrected device simulations, that the value of the barrier lowering obtained\nthrough the CV based method is totally inconsistent with the barrier lowering\nused to correct the inversion charge and that the extracted saturation\ninversion charge is underestimated."
    },
    {
        "anchor": "Vanadium gate-controlled Josephson half-wave nanorectifier: Recently, the possibility to tune the critical current of conventional\nmetallic superconductors via electrostatic gating was shown in wires, Josephson\nweak-links and superconductor-normal metal-superconductor junctions. Here we\nexploit such a technique to demonstrate a gate-controlled vanadium-based Dayem\nnano-bridge operated as a \\emph{half-wave} rectifier at $3$ K. Our devices\nexploit the gate-driven modulation of the critical current of the Josephson\njunction, and the resulting steep variation of its normal-state resistance, to\nconvert an AC signal applied to the gate electrode into a DC one across the\njunction. All-metallic superconducting gated rectifiers could provide the\nenabling technology to realize tunable photon detectors and diodes useful for\nsuperconducting electronics circuitry.",
        "positive": "2D Weyl Materials in the Presence of Constant Magnetic Fields: In this work we investigate the effect of a constant external, or artificial,\nmagnetic field on the nonlinear response of 2D Weyl materials. We calculate the\nLandau Levels for tilted cones in 2D Weyl materials by treating the tilting in\na perturbative manner, and employ perturbation theory to calculate the\ntilting-induced correction to the magnetic field induced Landau spectrum. We\nthen calculate the induced current as a function of the tilting coefficients\nand extract the correspondent nonlinear signal. Then, we analyze how changing\ntilting parameter affects nonlinear signal. Our findings show the possibility\nof achieving a significant tunability of the nonlinear response, by suitably\nengineering the orientation and degree of tilt of Dirac cones in 2D Weyl\nmaterials."
    },
    {
        "anchor": "Giant current-driven domain wall mobility in (Ga,Mn)As: We study theoretically hole current-driven domain wall dynamics in (Ga,Mn)As.\nWe show that the spin-orbit coupling causes significant hole reflection at the\ndomain wall, even in the adiabatic limit when the wall is much thicker than the\nFermi wavelength, resulting in spin accumulation and mistracking between\ncurrent-carrying spins and the domain wall magnetization. This increases the\nout-of-plane non-adiabatic spin transfer torque and consequently the\ncurrent-driven domain wall mobility by three to four orders of magnitude.\nTrends and magnitude of the calculated domain wall current mobilities agree\nwith experimental findings.",
        "positive": "Quantum resistance standard accuracy close to the zero-dissipation state: We report on a comparison of four GaAs/AlGaAs-based quantum resistance\nstandards using an original technique adapted from the well-known Wheatstone\nbridge. This work shows that the quantized Hall resistance at Landau level\nfilling factor $\\nu=2$ can be reproducible with a relative uncertainty of\n$32\\times 10^{-12}$ in the dissipationless limit of the quantum Hall effect\nregime. In the presence of a very small dissipation characterized by a mean\nmacroscopic longitudinal resistivity $\\bar{R_{xx}(B)}$ of a few $\\mu\\Omega$,\nthe discrepancy $\\Delta R_{\\mathrm{H}}(B)$ measured on the Hall plateau between\nquantum Hall resistors turns out to follow the so-called resistivity rule\n$\\bar{R_{xx}(B)}=\\alpha B\\times d(\\Delta R_{\\mathrm{H}}(B))/dB$. While the\ndissipation increases with the measurement current value, the coefficient\n$\\alpha$ stays constant in the range investigated ($40-120 \\mathrm{\\mu A}$).\nThis result enlightens the impact of the dissipation emergence in the\ntwo-dimensional electron gas on the Hall resistance quantization, which is of\nmajor interest for the resistance metrology. The quantum Hall effect is used to\nrealize a universal resistance standard only linked to the electron charge\n\\emph{e} and the Planck's constant \\emph{h} and it is known to play a central\nrole in the upcoming revised \\emph{Syst\\`eme International} of units. There are\ntherefore fundamental and practical benefits in testing the reproducibility\nproperty of the quantum Hall effect with better and better accuracy."
    },
    {
        "anchor": "Broadband reconfigurable logic gates in phonon waveguides: The high-quality-factor mechanical resonator in electromechanical systems has\nfacilitated dynamic control of phonons via parametric nonlinear processes and\npaved the development of mechanical logic-elements. However the resonating\nelement with a narrow bandwidth limits the resultant operation speeds as well\nas constraining the availability of nonlinear phenomena to a narrow spectral\nrange. To overcome these drawbacks we have developed phonon waveguides in which\nthe mechanical analogue of four-wave-mixing is demonstrated that enables the\nfrequency of phonon waves to be converted over 1 MHz. We harness this platform\nto execute multiple binary mechanical logic gates in parallel, via frequency\ndivision multiplexing in a two-octave-wide phonon transmission band, where each\ngate can be independently reconfigured. The fidelity of the binary gates is\nverified via temporal measurements yielding eye diagrams which confirm the\navailability of high speed logic operations. The phonon waveguide architecture\nthus offers the broadband functionality that is essential to realising\nmechanical signal processors.",
        "positive": "Directly Visualizing the Crossover from Incoherent to Coherent Phonons\n  in Two-dimensional Periodic MoS2/MoSe2 Arrayed Heterostructure: Recently, massive efforts have been done on controlling thermal transport via\ncoherent phonons in the various periodic nanostructures. However, the intrinsic\nlattice difference between the constituent materials inevitably generates the\ndisorder at the interfaces, thus limiting the opportunity of directly observing\nthe coherent phonon transport. Here, we investigate the controllability and\nvisualization of the coherent phonon transport in a periodic MoS2/MoSe2 arrayed\nheterostructure with minimum lattice mismatching using non-equilibrium\nmolecular dynamics simulation. It is found that the coherent phonon transport\ncan be destroyed and rebuilt through adjusting the density of MoSe2 nanodot\narrays. The phonon localization induced by the destruction of correlation is\nvisualized based on the spatial energy distribution and anharmonic analysis.\nFurthermore, the eigen vector diagrams provide a distinct visualization of the\nlocalized phonon modes. Besides, the correlation of phonon can be rebuilt by\nreducing the period length, which is verified by the enhanced group velocities\nextracted from phonon dispersion curves. Interestingly, the crossover from\nincoherent to coherent phonon transport is directly observed by the spatial\nenergy distributions and the spectral phonon transmission coefficients.\nFinally, the size and temperature dependence of thermal conductivity are also\ndiscussed. This study of the phonon coherence and its visualizing manipulation\non thermal conductivity will be beneficial to fine heat control and management\nin the real applications."
    },
    {
        "anchor": "Heterodimer nanostructures induced energy focusing on metal film: As an interesting surface plasmon phenomenon discovered several years ago,\nelectromagnetic field redistribution in nanoparticle dimer on film system\nprovides a novel thought to enhance the light power on a plain film which could\nbeen widely used in surface enhanced Raman scattering (SERS), solar cells,\nphoto-catalysis, etc. Homodimers on film are mainly investigated in past years,\nwhile the properties of heterodimers on film are still unclear. In this work,\nsize difference induced electromagnetic field redistribution in Ag nanoparticle\ndimer on Au film system is investigated first. The results obtained from finite\nelement method indicate that the smaller nanoparticle has much greater ability\nto focus light energy on Au film, which even reached more than 5 time compared\nto the larger one. Further researches indicate that this energy focusing\nability has a strong relationship to the wavelength and diameter ration in\ndimer. Similar focusing phenomenon is found in the system of thick wire-smaller\nparticle on film. Later, the SERS spectra collected in the small\nnanoparticle-large nanowire system provide an experimental evidence for this\ntheoretic predication. Our results strengthen the understanding of surface\nplasmon on plane film and have potential application prospects in the surface\nplasmon related fields.",
        "positive": "Theory of Current Noise and Photon Noise in Quantum Cascade Lasers: A comprehensive model for the photon number fluctuations and the current\nnoise in quantum cascade lasers is presented. It is shown that the photon\nintensity noise in quantum cascade lasers exhibits little amplitude squeezing\neven when noise in the drive current is suppressed below the shot noise value.\nThis is in contrast to interband semiconductor diode lasers in which the laser\nintensity noise can be squeezed well below the shot noise limit by high\nimpedance suppression of fluctuations in the drive current. The theoretical\nmodel presented in this paper self-consistently accounts for the suppression of\ncurrent noise in electron transport in multiple quantum well structures due to\nvarious electronic correlations. The nature of these electronic correlations is\ndiscussed. Mechanisms responsible for the reduced photon number squeezing in\nintersubband lasers are elucidated. Scaling of the laser intensity noise and\nthe current noise with the number of cascaded gain stages is also described.\nDirect current modulation response of quantum cascade lasers is also studied,\nand it is shown that contrary to the predictions in the literature of terahertz\nmodulation bandwidth for these lasers, bandwidth of almost all quantum cascade\nlasers that have been reported in the literature is limited by the inverse\nphoton lifetime inside the laser cavity to tens of gigahertz."
    },
    {
        "anchor": "Topological effects in magnetic platinum nano-particles: The magnetic properties of platinum nano-particles ranging in size from a few\nto up 300 atoms are investigated through first-principle calculations. It is\nfound that the total magnetization depends strongly on the local atomic\nrearrangements, with an enhancement around five-fold axis. This is due to an\nelongation of the nearest neighbor distance together with a contraction of the\n2$^{nd}$ distance, resulting in a net interatomic partial charge transfer from\nthe atoms lying on the sub-surface layer (donor) towards the vertexes\n(acceptor).",
        "positive": "Fermi-sea-like correlations in a partially filled Landau level: The pair distribution function and the static structure factor are computed\nfor composite fermions. Clear and robust evidence for a $2k_F$ structure is\nseen in a range of filling factors in the vicinity of the half-filled Landau\nlevel. Surprisingly, it is found that filled Landau levels of composite\nfermions, i.e. incompressible FQHE states, bear a stronger resemblance to a\nFermi sea than do filled Landau levels of electrons."
    },
    {
        "anchor": "Thermoelectric phenomena in a quantum dot asymmetrically coupled to\n  external leads: We study thermoelectric phenomena in a system consisting of strongly\ncorrelated quantum dot coupled to external leads in the Kondo regime. We\ncalculate linear and nonlinear electrical and thermal conductance and\nthermopower of the quantum dot and discuss the role of asymmetry in the\ncouplings to external electrodes. In the linear regime electrical and thermal\nconductances are modified, while thermopower remains unchanged. In the\nnonlinear regime the Kondo resonance in differential conductance develops at\nnon-zero source-drain voltage, which has important consequences on\nthermoelectric properties of the system and the thermopower starts to depend on\nthe asymmetry. We also discuss Wiedemann-Franz relation, thermoelectric figure\nof merit and validity of the Mott formula for thermopower.",
        "positive": "Coherent control of three-spin states in a triple quantum dot: Spin qubits involving individual spins in single quantum dots or coupled\nspins in double quantum dots have emerged as potential building blocks for\nquantum information processing applications. It has been suggested that triple\nquantum dots may provide additional tools and functionalities. These include\nthe encoding of information to either obtain protection from decoherence or to\npermit all-electrical operation, efficient spin busing across a quantum\ncircuit, and to enable quantum error correction utilizing the three-spin\nGreenberger-Horn-Zeilinger quantum state. Towards these goals we demonstrate\nfor the first time coherent manipulation between two interacting three-spin\nstates. We employ the Landau-Zener-St\\\"uckelberg approach for creating and\nmanipulating coherent superpositions of quantum states. We confirm that we are\nable to maintain coherence when decreasing the exchange coupling of one spin\nwith another while simultaneously increasing its coupling with the third. Such\ncontrol of pairwise exchange is a requirement of most spin qubit architectures\nbut has not been previously demonstrated."
    },
    {
        "anchor": "Tunnel junctions with moir\u00e9 superlattice as barrier: Recently, moir\\'{e} superlattices have attracted considerable attentions\nbecause they are found to exhibit intriguing electronic phenomena of tunable\nMott insulators and unconventional superconductivity. These phenomena are\nhighly related to the physical mechanism of the interlayer coupling. However,\nup to now, there has not existed any theory that can completely interpret the\nexperimental results of the interlayer conductance of moir\\'{e} superlattice.\nIn order to solve this problem, the superposition of periods and the\ncorresponding coherence, which are the essential characteristics of moir\\'{e}\nsuperlattice, should be considered more sufficiently. Therefore, it is quite\nnecessary to introduce optical methods to study moir\\'{e} superlattices. Here,\nwe develop a theory for moir\\'{e} superlattices which are founded on\ntraditional optical scattering theory. The theory can interpret both the\ncontinuously decreasing background and the peak of the interlayer conductance\nobserved in the experiments by a unified mechanism. We show that, the\ndecreasing background of the interlayer conductance arises from the increasing\nstrength of the interface potential, and the peak roots from the scattering\nresonance of the interface potential. The present work is crucial for\nunderstanding the interlayer coupling of the moir\\'{e} superlattice, and\nprovide a solid theoretical foundation for the application of moir\\'{e}\nsuperlattice.",
        "positive": "Comment on \"Floquet topological phase transition in the\n  $\u03b1$--$\\mathcal{T}_{3}$ lattice\": A recent paper studied the topological phase transition driven by the\ncircular frequency light in the $\\alpha$--$\\mathcal{T}_{3}$ lattice. In this\nComment we point out that there is a flaw in the derivation of the effective\nHamiltonian in this paper."
    },
    {
        "anchor": "Organic Spintronics: In this paper we review the recent field of organic spintronics, where\norganic materials are applied as a medium to transport and control\nspin-polarized signals. The contacts for injecting and detecting spins are\nformed by metals, oxides, or inorganic semiconductors. First, the basic\nconcepts of spintronics and organic electronics are addressed and phenomena\nwhich are in particular relevant for organic spintronics are highlighted.\nExperiments using different organic materials, including carbon nanotubes,\norganic thin films, self-assembled monolayers and single molecules are then\nreviewed. Observed magnetoresistance points toward successful spin injection\nand detection, but spurious magnetoresitance effects can easily be confused\nwith spin accumulation. A few studies report long spin relaxation times and\nlengths, which forms a promising basis for further research. We conclude with\ndiscussing outstanding questions and problems.",
        "positive": "Kondo enhancement of current induced spin accumulation in a quantum dot: Weak spin-orbit coupling produces very limited current induced spin\naccumulation in semiconductor nanostructures. We demonstrate a possibility to\nincrease parametrically the spin polarization using the Kondo effect. As a\nmodel object we consider a quantum dot side coupled to a quantum wire taking\ninto account the spin dependent electron tunneling from the wire to the dot.\nUsing the nonequilibrium Green's functions, we show that the many body\ncorrelations between the quantum dot and the quantum wire can increase the\ncurrent induced spin accumulation at low temperatures by almost two orders of\nmagnitude for the moderate system parameters. The enhancement is related to the\nKondo peak formation in the density of states and the spin instability due to\nthe strong Coulomb interaction. This effect may be useful to electrically\nmanipulate the localized electron spins in quantum dots for their quantum\napplications."
    },
    {
        "anchor": "Enhancement of tunneling density of states at a junction of three\n  Luttinger liquid wires: We study the tunneling density of states (TDOS) for a junction of three\nTomonaga-Luttinger liquid wires. We show that there are fixed points which\nallow for the enhancement of the TDOS, which is unusual for Luttinger liquids.\nThe distance from the junction over which this enhancement occurs is of the\norder of x = v/(2 \\omega), where v is the plasmon velocity and \\omega is the\nbias frequency. Beyond this distance, the TDOS crosses over to the standard\nbulk value independent of the fixed point describing the junction. This finite\nrange of distances opens up the possibility of experimentally probing the\nenhancement in each wire individually.",
        "positive": "Spin-Hall nanooscillator based on an antiferromagnetic domain wall: We propose here a high-frequency spin-Hall nano-oscillator based on a simple\nmagnetic texture, such as a domain wall, located in an antiferromagnet with\neasy-axis anisotropy type. We show that the spin current, polarized along the\nanisotropy axis, excites a conical precession of the N\\'eel vector in such a\ndomain wall, which allows obtaining a robust ac output signal, -- contrary to\nthe planar precession in an uniform uniaxial antiferromagnet, where ac output\nis hard to achieve. The frequency of the auto-oscillations is easily tunable by\nthe applied current up to the THz range, and the threshold current vanishes for\npure uniaxial antiferromagnet. By micro-magnetic simulations, we demonstrate\nthat the pinning of the domain wall is crucial for the oscillator design, which\ncan be achieved in nano-constriction layout of the free layer."
    },
    {
        "anchor": "Anomalous polarization conversion in arrays of ultrathin ferromagnetic\n  nanowires: We study optical properties of arrays of ultrathin nanowires by means of the\nBrillouin scattering of light on magnons. We employ the Stokes/anti-Stokes\nscattering asymmetry to probe the circular polarization of a local electric\nfield induced inside nanowires by linearly polarized light waves. We observe\nthe anomalous polarization conversion of the opposite sign than that in a bulk\nmedium or thick nanowires with a great enhancement of the degree of circular\npolarization attributed to an unconventional refraction in the nanowire medium.",
        "positive": "Sustained biexciton emission in colloidal quantum wells assisted by\n  dopant-host interaction: Biexcitons have been considered as one of the fundamental building blocks for\nquantum technology because of its overwhelming advantages in generating\nentangled photon pairs. Although many-body complexes have been demonstrated\nrecently in mono-layer transition metal dichalcogenides (TMDs), the low\nemission efficiency and scale up capability hinder their applications.\nColloidal nanomaterials, with high quantum efficiency and ease of\nsynthesis/processing, are regarded to be an appealing complement to TMDs for\nbiexciton sources. However, a progress towards biexciton emission in colloidal\nnanomaterials has been challenging largely by small binding energy and\nultrafast non-radiative multiexciton recombination. Here, we demonstrate\nroom-temperature biexciton emission in Cu-doped CdSe colloidal quantum wells\n(CQWs) under continuous-wave excitation with intensity as low as ~10 W/cm2. The\ncharacteristics of radiative biexciton states are investigated by their super\nlinear emission with respect to excitation power, thermal stability and\ntransient photophysics. The interaction between the quantum confined host\ncarriers and the dopant ions increases biexciton binding energy by two folds\ncompared to the undoped CQWs. Such strong binding energy together with\nsuppressed Auger recombination and efficient, spectrally narrow\nphotoluminescence in a quasi-2D semiconductor enables sustained biexciton\nemission at room temperature, providing a potential solution for efficient,\nscalable and stand-alone quantum devices."
    },
    {
        "anchor": "Dramatic impact of pumping mechanism on photon entanglement in\n  microcavity: A theory of entangled photons emission from quantum dot in microcavity under\ncontinuous and pulsed incoherent pumping is presented. It is shown that the\ntime-resolved two-photon correlations drastically depend on the pumping\nmechanism: the continuous pumping quenches the polarization entanglement and\nstrongly suppresses photon correlation times. Analytical theory of the effect\nis presented.",
        "positive": "Controllable skyrmion chirality in ferroelectrics: Chirality, an intrinsic handedness, is one of the most intriguing fundamental\nphenomena in nature. Materials composed of chiral molecules find broad\napplications in areas ranging from nonlinear optics and spintronics to biology\nand pharmaceuticals. However, chirality is usually an invariable inherent\nproperty of a given material that cannot be easily changed at will. Here, we\ndemonstrate that ferroelectric nanodots support skyrmions the chirality of\nwhich can be controlled and switched. We devise protocols for realizing control\nand efficient manipulations of the different types of skyrmions. Our findings\nopen the route for controlled chirality with potential applications in\nferroelectric-based information technologies."
    },
    {
        "anchor": "Highly anisotropic commensurability oscillations in two-dimensional\n  holes at the GaAs/AlGaAs (311)A interface: Measurements of commensurability oscillations in GaAs/AlGaAs two-dimensional\n(2D) hole systems grown on GaAs (311)A substrates reveal a remarkable\nanisotropy: the amplitude of the measured commensurability oscillations along\nthe [$\\bar{2}$33] direction is about 100 times larger than along [01$\\bar{1}$].\nFor 2D electron systems at similar interfaces, however, we observe nearly\nisotropic oscillations, suggesting that the anomalous anisotropy is intrinsic\nto GaAs 2D holes at the (311)A interface.",
        "positive": "Field-driven metamorphoses of isolated skyrmions within the conical\n  state of cubic helimagnets: Topologically stable field configurations appear in many fields of physics,\nfrom elementary particles to condensed matter and cosmology. During the last\ndecade, chiral liquid crystals and chiral magnets took on the role of model\nobjects for experimental investigation of topological solitons and\nunderstanding of their nonsingular field configurations. Here we introduce a\nparadigm of facile skyrmionic networks with mutually-orthogonal orientations of\nconstituent isolated skyrmions. Such networks are envisioned as a novel concept\nof spintronic devices and are presumably responsible for precursor phenomena\nnear the ordering temperatures of bulk cubic helimagnets. In particular, we\ndemonstrate an interconversion between mutually orthogonal skyrmions:\nhorizontal skyrmions swirl into an intermediate spring-like states and\nsubsequently squeeze into vertical skyrmions with both polarities. Skyrmion\ntubes are also considered as building blocks for particle-like states with more\ninvolved internal structure. A family of target-skyrmions, which includes an\noverlooked so far type with a multiple topological charge, is formed owing to\nthe tendency to minimize the interaction energy between vertical and horizontal\nskyrmions. The conical phase serves as a suitable background for considered\nskyrmion evolution. It substantializes the attracting skyrmion-skyrmion\ninteraction in the skyrmionic networks, shapes their internal structure and\nguides the nucleation processes. Alternatively, intricate textural changes of\nisolated skyrmions result not only in the structural deformations of a host\nconical state, but may lead to the formation of an exotic skyrmion order with\npairs of merons being the core of the game. Generically, the fundamental\ninsights provided by this work emphasize a three-dimensional character of\nskyrmion metamorphoses and can also be extended to three-dimensional solitons,\nsuch as hopfions."
    },
    {
        "anchor": "Local removal of silicon layers on Si(100)-2x1 with chlorine-resist STM\n  lithography: We report the realization of STM-based lithography with silicon layers\nremoval on the chlorinated Si(100)-2x1 surface at 77 K. In contrast to other\nSTM lithography studies, we were able to remove locally both chlorine and\nsilicon atoms. Most of the etched pits have a lateral size of 10-20 A and a\ndepth of 1-5 A. In the pits in which the STM image with atomic resolution is\nobtained, the bottom is mainly covered with chlorine. Some pits contain\nchlorine vacancies. Mechanisms of STM-induced removal of silicon and chlorine\natoms on Si(100)-2x1-Cl are discussed and compared with the well-studied case\nof STM-induced hydrogen desorption on Si(100)-2x1-H. The results open up new\npossibilities of the three-dimensional local etching with STM lithography.",
        "positive": "Electric-Field Control over Spin-Wave and Current Induced Domain Wall\n  Motion and Magnonic Torques in Multiferroics: We discover that the way spin-waves exert magnetic torques in multiferroic\nmaterials can cause not only domain wall motion, but also magnetization\ndynamics for homogeneous magnetization textures. Interestingly, the domain wall\nmotion can be controlled via purely electrical means with the spin-waves being\ngenerated by an ac electric field $E$ while the direction of the wall motion\nalso is sensitive to an applied dc $E$ field. Moreover, we determine the\ninteraction between spin-transfer torque from an electric current and a\nmagnetic domain wall in multiferroics and show that the Walker breakdown\nthreshold scales with the magnitude of a perpendicular electric field, offering\na way to control the properties of domain wall propagation via electric gating."
    },
    {
        "anchor": "Thermophoresis of an Antiferromagnetic Soliton: We study dynamics of an antiferromagnetic soliton under a temperature\ngradient. To this end, we start by phenomenologically constructing the\nstochastic Landau-Lifshitz-Gilbert equation for an antiferromagnet with the aid\nof the fluctuation-dissipation theorem. We then derive the Langevin equation\nfor the soliton's center of mass by the collective coordinate approach. An\nantiferromagentic soliton behaves as a classical massive particle immersed in a\nviscous medium. By considering a thermodynamic ensemble of solitons, we obtain\nthe Fokker-Planck equation, from which we extract the average drift velocity of\na soliton. The diffusion coefficient is inversely proportional to a small\ndamping constant $\\alpha$, which can yield a drift velocity of tens of m/s\nunder a temperature gradient of $1$ K/mm for a domain wall in an easy-axis\nantiferromagnetic wire with $\\alpha \\sim 10^{-4}$.",
        "positive": "Revealing molecular orbital gating by transition-voltage spectroscopy: Recently, Song et al [Nature 462, 1039 (2009)] employed transition-voltage\nspectroscopy to demonstrate that the energy $\\varepsilon_H$ of the highest\noccupied molecular orbital (HOMO) of single-molecule transistors can be\ncontrolled by a gate potential $V_G$. To demonstrate the linear dependence\n$\\varepsilon_H-V_G$, the experimental data have been interpreted by modeling\nthe molecule as an energy barrier spanning the spatial source-drain region of\nmolecular junctions. Since, as shown in this work, that crude model cannot\nquantitatively describe the measured $I$-$V$-characteristics, it is important\nto get further support for the linear dependence of $\\varepsilon_H$ on $V_G$.\nThe results presented here, which have been obtained within a model of a\npoint-like molecule, confirm this linear dependence. Because the two models\nrely upon complementary descriptions, the present results indicate that the\ninterpretation of the experimental results as evidence for a gate controlled\nHOMO is sufficiently general."
    },
    {
        "anchor": "Review on carrier multiplication in graphene: The remarkable gapless and linear band structure of graphene opens up new\ncarrier relaxation channels bridging the valence and the conduction band. These\nAuger scattering processes change the number of charge carriers and can give\nrise to a significant multiplication of optically excited carriers in graphene.\nThis is an ultrafast many-particle phenomenon that is of great interest both\nfor fundamental many-particle physics as well as technological applications.\nHere, we review the research on carrier multiplication in graphene and\nLandau-quantized graphene including theoretical modelling and experimental\ndemonstration.",
        "positive": "Electrical Control of Second-Harmonic Generation in a WSe2 Monolayer\n  Transistor: Nonlinear optical frequency conversion, in which optical fields interact with\na nonlinear medium to produce new field frequencies, is ubiquitous in modern\nphotonic systems. However, the nonlinear electric susceptibilities that give\nrise to such phenomena are often challenging to tune in a given material, and\nso far, dynamical control of optical nonlinearities remains confined to\nresearch labs as a spectroscopic tool. Here, we report a mechanism to\nelectrically control second-order optical nonlinearities in monolayer WSe2, an\natomically thin semiconductor. We show that the intensity of second-harmonic\ngeneration at the A-exciton resonance is tunable by over an order of magnitude\nat low temperature and nearly a factor of 4 at room temperature through\nelectrostatic doping in a field-effect transistor. Such tunability arises from\nthe strong exciton charging effects in monolayer semiconductors, which allow\nfor exceptional control over the oscillator strengths at the exciton and trion\nresonances. The exciton-enhanced second-harmonic generation is\ncounter-circularly polarized to the excitation laser, arising from the\ncombination of the two-photon and one-photon valley selection rules that have\nopposite helicity in the monolayer. Our study paves the way towards a new\nplatform for chip-scale, electrically tunable nonlinear optical devices based\non two-dimensional semiconductors."
    },
    {
        "anchor": "Few-layer graphene patterned bottom gates for van der Waals\n  heterostructures: We introduce a method of local gating for van der Waals heterostructures,\nemploying a few-layer graphene patterned bottom gate. Being a member of the 2D\nmaterial family, few-layer graphene adapts perfectly to the commonly used\nstacking method. Its versatility regarding patterning as well as its flatness\nmake it an ideal candidate for experiments on locally gated 2D materials.\nMoreover, in combination with ultra-thin hexagonal boron nitride as an\ninsulating layer, sharp potential steps can be created and the quality of the\ninvestigated 2D material can be sustained. To underline the good feasibility\nand performance, we show results on transport experiments in periodically\nmodulated graphene- boron nitride heterostructures, where the charge carrier\ndensity is tuned via locally acting patterned few layer graphene bottom gates\nand a global back gate.",
        "positive": "Scaling and interaction-assisted transport in graphene with\n  one-dimensional defects: We analyze the scattering from one-dimensional defects in intrinsic graphene.\nThe Coulomb repulsion between electrons is found to be able to induce\nsingularities of such scattering at zero temperature as in one-dimensional\nconductors. In striking contrast to electrons in one space dimension, however,\nrepulsive interactions here can enhance transport. We present explicit\ncalculations for the scattering from vector potentials that appear when strips\nof the material are under strain. There the predicted effects are exponentially\nlarge for strong scatterers."
    },
    {
        "anchor": "Changes of Kondo effect in the junction with DIII-class topological and\n  $s$-wave superconductors: We discuss the change of the Kondo effect in the Josephson junction formed by\nthe indirect coupling between a one-dimensional \\emph{DIII}-class topological\nand s-wave superconductors via a quantum dot. By performing the\nSchrieffer-Wolff transformation, we find that the single-electron occupation in\nthe quantum dot induces various correlation modes, such as the Kondo and\nsinglet-triplet correlations between the quantum dot and the $s$-wave\nsuperconductor and the spin exchange correlation between the dot and Majorana\ndoublet. Moreover, it plays a nontrivial role in modifying the Josephson\neffect, leading to the occurrence of anisotropic and high-order Kondo\ncorrelation. In addition, due to the quantum dot in the Kondo regime, extra\nspin exchange correlations contribute to the Josephson effect as well.\nNevertheless, if the \\emph{DIII}-class topological superconductor degenerates\ninto \\emph{D}-class because of the destruction of time-reversal invariance, all\nsuch terms will disappear completely. We believe that this work shows the\nfundamental difference between the \\emph{D}- and \\emph{DIII}-class topological\nsuperconductors.",
        "positive": "Operation of Quantum Cellular Automaton cells with more than two\n  electrons: We present evidence that operation of QCA (Quantum Cellular Automaton) cells\nwith four dots is possible with an occupancy of 4N+2 electrons per cell (N\nbeing an integer). We show that interaction between cells can be described in\nterms of a revised formula for cell polarization, which is based only on the\ndifference between diagonal occupancies. We validate our conjectures with full\nquantum simulations of QCA cells for a number of electrons varying from 2 to 6,\nusing the Configuration-Interaction method."
    },
    {
        "anchor": "Collective Wigner crystal tunneling in carbon nanotubes: The collective tunneling of a a Wigner necklace - a crystalline state of a\nsmall number of strongly interacting electrons confined to a suspended nanotube\nand subject to a double well potential - is theoretically analyzed and compared\nwith experiments in [Shapir $\\textit{et al.}$, Science $\\textbf {364}$, 870\n(2019)]. Density Matrix Renormalization Group computations, exact\ndiagonalization, and instanton theory provide a consistent description of this\nvery strongly interacting system, and show good agreement with experiments.\nExperimentally extracted and theoretically computed tunneling amplitudes\nexhibit a scaling collapse. Collective quantum fluctuations renormalize the\ntunneling, and substantially enhance it as the number of electrons increases.",
        "positive": "Driven dissipative dynamics of spins in quantum dots: We have studied the dissipative dynamics of a driven electronic spin trapped\nin a quantum dot. We consider the dissipative mechanism as due to the indirect\ncoupling of the electronic spin to acoustic phonons via the\nspin-orbit/electron-phonon couplings. Using an effective spectral function of\nthe dissipative phonon bath, we evaluated the expectation values of the spin\ncomponents through the Bloch-Redfield theory. We show that due to a sharp bath\nresonance present in the effective spectral function, with typical energy much\nsmaller than the electronic confinement energy, the dissipative spin has a rich\ndynamical behavior that helps us to determine some features of the spin-bath\ncoupling. We also quantify the effects produced by the sharp bath resonance,\nand thus indicate the best regimes of operation in order to achieve the longest\nrelaxation times for the spin."
    },
    {
        "anchor": "Berry phase correction to electron density in solids and \"exotic\"\n  dynamics: Recent results on the semiclassical dynamics of an electron in a solid are\nexplained using techniques developed for ``exotic'' Galilean dynamics. The\nsystem is indeed Hamiltonian and Liouville's theorem holds for the symplectic\nvolume form. Suitably defined quantities satisfy hydrodynamic equations.",
        "positive": "Strain manipulation of Majorana fermions in graphene: The functionalized graphene with induced superconductivity, Zeeman coupling,\nand finite Rashba spin-orbit coupling is proposed to display topological\nsuperconducting phases with Majorana end modes. We obtain the phase diagram of\nbulk graphene and nanoribbon by calculating the Chern number, band structure\nand wavefunction. The electron doping in graphene, magnetic field and\nstrain-induced pseudomagnetic field can result in the topological phase\ntransition. Moreover, it is interested to note that strain has negative\ninfluence on the stability of topological nontrivial phase either uniform or\nnonuniform, destroying the existence of Majorana fermion, which provides a new\nway to transfer, create and fuse Majorana fermions. Some experimental schemes\nare also introduced to tailor functionalized graphene, generating various\ndevices applied in topological quantum computation."
    },
    {
        "anchor": "An experimentally accessible quality factor for Majorana wires: Spin-orbit coupled semiconducting nanowires with proximity-induced\nsuperconductivity are expected to host Majorana zero modes at their endpoints\nwhen a sufficiently strong magnetic field is applied. The resulting phase would\nbe a one-dimensional topological superconductor. However, while a variety of\nexperiments have been performed observing a zero bias conductance peak\n(suggestive of Majorana zero modes), the topological nature of these physical\nsystems is still a subject of debate. Here we suggest a quantitative test of\nthe degree to which a system displaying a zero bias peak may be considered\ntopological. The experiment is similar to previous measurements of conductance,\nbut is performed with the aid of a quantum dot at the wire's end. We arrive at\nthe surprising result that the non-local nature of the topological system may\nbe identified through a local measurement.",
        "positive": "Thermoelectric effects in topological crystalline insulators: We investigate the electrical conductivity and thermoelectric effects in\ntopological crystalline insulators in the presence of short- and long-range\nimpurity interactions. We employ the generalized Boltzmann formalism for\nanisotropic Fermi surface systems. The conductivity exhibits a local minimum as\ndoping varies owing to the Van Hove singularity in the density of states\noriginated from the saddle point in the surface states band structure.\nSuppression of the interband scattering of the charge carriers at high-energy\nDirac points results in a maximum in the electrical conductivity. Whenever the\nFermi level passes an extremum in the conductivity, Seebeck coefficient changes\nsign. In addition, it is revealed that profound thermoelectric effects can be\nattained around these extrema points."
    },
    {
        "anchor": "Floquet topological phase transitions in a kicked Haldane-Chern\n  insulator: We consider a periodically $\\delta$-kicked Haldane type Chern insulator with\nthe kicking applied in the $\\hat{z}$ direction. This is known to behave as an\ninversion symmetry breaking perturbation, since it introduces a time-dependent\nstaggered sub-lattice potential. We study here the effects of such driving on\nthe topological phase diagram of the original Haldane model of a Hall effect in\nthe absence of a net magnetic field. The resultant Floquet band topology is\nagain that of a Chern insulator with the driving parameters, frequency and\namplitude, influencing the inversion breaking mass $M$ of the undriven Haldane\nmodel. A family of such, periodically related, `Semenoff masses' is observed to\noccur which support a periodic repetition of Haldane like phase diagrams along\nthe inversion breaking axis of the phase plots. Out of these it is possible to\nidentify two in-equivalent masses in the reduced zone scheme of the Floquet\nquasienergies, which form the centres of two inequivalent phase diagrams.\nFurther, variation in the driving amplitude's magnitude alone is shown to\neffect the topological properties by linearly shifting the phase diagram of the\ndriven model about the position of the undriven case. A phenomenon that allows\nthe study of Floquet topological phase transitions in the system. Finally, we\nalso discuss some issues regarding the modifications to Haldane's condition for\npreventing band overlaps at the Dirac point touchings in the Brillouin zone, in\nthe presence of kicking.",
        "positive": "Bound states and persistent currents in topological insulator rings: We analyze theoretically the bound state spectrum of an Aharonov Bohm (AB)\nring in a two-dimensional topological insulator using the four-band model of\nHgTe-quantum wells as a concrete example. We calculate analytically the\ncircular helical edge states and their spectrum as well as the bound states\nevolving out of the bulk spectrum as a function of the applied magnetic flux\nand dimension of the ring. We also analyze the spin-dependent persistent\ncurrents, which can be used to measure the spin of single electrons. We further\ntake into account the Rashba spin-orbit interaction which mixes the spin states\nand derive its effect on the ring spectrum. The flux tunability of the ring\nstates allows for coherent mixing of the edge- and the spin degrees of freedom\nof bound electrons which could be exploited for quantum information processing\nin topological insulator rings."
    },
    {
        "anchor": "Si Nanowire - Array Source Gated Transistors: Solution processed field-effect transistors based on single crystalline\nsilicon nanowires (Si NWs) with metal Schottky contacts are demonstrated. The\nsemiconducting layer was deposited from a nanowire ink formulation at room\ntemperature. The devices with 230nm thick SiO2 gate insulating layers show\nexcellent output current-voltage characteristics with early saturation voltages\nunder 2 volts, constant saturation current and exceptionally low dependence of\nsaturation voltage with the gate field. Operational principles of these devices\nare markedly different from traditional ohmic-contact field-effect transistors\n(FETs), and are explained using the source-gated transistor (SGT) concept in\nwhich the semiconductor under the reverse biased Schottky source barrier is\ndepleted leading to low voltage pinch-off and saturation of drain current.\nDevice parameters including activation energy are extracted at different\ntemperatures and gate voltages to estimate the Schottky barrier height for\ndifferent electrode materials to establish transistor performance - barrier\nheight relationships. Numerical simulations are performed using 2D thin-film\napproximation of the device structures at various Schottky barrier heights.\nWithout any adjustable parameters and only assuming low p-doping of the\ntransistor channel, the modelled data show exceptionally good correlation with\nthe measured data. From both experimental and simulation results, it is\nconcluded that source-barrier controlled nanowire transistors have excellent\npotential advantages compared with a standard FET including mitigation of\nshort-channel effects, insensitivity in device operating currents to device\nchannel length variation, higher on/off ratios, higher gain, lower power\nconsumption and higher operational speed for solution processable and printable\nnanowire electronics.",
        "positive": "Hartree-Fock based diagonalization: an efficient method for simulating\n  disordered interacting electrons: We present an efficient numerical method for simulating the low-energy\nproperties of disordered many-particle systems. The method which is based on\nthe quantum-chemical configuration interaction approach consists in\ndiagonalizing the Hamiltonian in an energetically truncated basis build of the\nlow-energy states of the corresponding Hartree-Fock Hamiltonian. As an example\nwe investigate the quantum Coulomb glass, a model of spinless electrons in a\nrandom potential interacting via long-range Coulomb interaction. We find that\nthe Coulomb interaction increases the conductance of strongly disordered\nsystems but reduces the conductance of weakly disordered systems."
    },
    {
        "anchor": "Universal spectral moment theorem and its applications in non-Hermitian\n  systems: The high sensitivity of the spectrum and wavefunctions to boundary\nconditions, termed the non-Hermitian skin effect, represents a fundamental\naspect of non-Hermitian systems. While it endows non-Hermitian systems with\nunprecedented physical properties, it presents notable obstacles in grasping\nuniversal properties that are robust against microscopic details and boundary\nconditions. In this Letter, we introduce a pivotal theorem: in the\nthermodynamic limit, for any non-Hermitian systems with finite-range\ninteractions, all spectral moments are invariant quantities, independent of\nboundary conditions, posing strong constraints on the spectrum. Utilizing this\ninvariance, we propose an analytic criterion for parity-time ($\\mathcal{PT}$)\nexactness that is applicable in any dimensions with any boundary conditions. we\nfind that the $\\mathcal{PT}$ transition identified using this method captures\ndynamical signatures observable in experiments, aligns with the exceptional\npoint, and is distinct from the real-to-complex spectral transition, contrary\nto traditional expectations. We verify these findings in 1D and 2D lattice\nmodels.",
        "positive": "Fabry-P\u00e9rot interference in gapped bilayer graphene with broken\n  anti-Klein tunneling: We report the experimental observation of Fabry-P\\'erot (FP) interference in\nthe conductance of a gate-defined cavity in a dual-gated bilayer graphene (BLG)\ndevice. The high quality of the BLG flake, combined with the device's\nelectrical robustness provided by the encapsulation between two hexagonal boron\nnitride layers, allows us to observe ballistic phase-coherent transport through\na $1${\\mu}m-long cavity. We confirm the origin of the observed interference\npattern by comparing to tight-binding calculations accounting for the\ngate-tunable bandgap. The good agreement between experiment and theory, free of\ntuning parameters, further verifies that a gap opens in our device. The gap is\nshown to destroy the perfect reflection for electrons traversing the barrier\nwith normal incidence (anti-Klein tunneling). The broken anti-Klein tunneling\nimplies that the Berry phase, which is found to vary with the gate voltages, is\nalways involved in the FP oscillations regardless of the magnetic field, in\nsharp contrast with single-layer graphene."
    },
    {
        "anchor": "Moir\u00e9-induced optical non-linearities: Single and multi-photon\n  resonances: Moir\\'e excitons promise a new platform with which to generate and manipulate\nhybrid quantum phases of light and matter in unprecedented regimes of\ninteraction strength. We explore the properties in this regime, through studies\nof a Bose-Hubbard model of excitons coupled to cavity photons. We show that the\nsteady states exhibit a rich phase diagram with pronounced bi-stabilities\ngoverned by multi-photon resonances reflecting the strong inter-exciton\ninteractions. In the presence of an incoherent pumping of excitons we find that\nthe system can realise one- and multi-photon lasers.",
        "positive": "In-Plane Breathing and Shear Modes in Low-Dimensional Nanostructures: We use continuum elasticity theory to revise scaling laws for radial\nbreathing-like and shear-like vibration modes in quasi-2D nanostructures\nincluding finite-width nanoribbons and finite-size thin circular discs. Such\nmodes can be observed spectroscopically in corresponding nanostructures of\ngraphene and phosphorene and can be determined numerically by atomistic <i> ab\ninitio</i> density functional theory and classical force-field calculation. The\nrevised scaling laws differ from previously used expressions, some of which\ndisplay an unphysical asymptotic behavior. Apart from model assumptions\ndescribing the effect of edge termination, the continuum scaling laws have no\nadjustable parameters and display correct asymptotic behavior. These scaling\nlaws yield excellent agreement with experimental and numerical results for\nvibration frequencies in both isotropic and anisotropic structures as well as\nuseful expressions for the frequency dependence on structure size and edge\ntermination."
    },
    {
        "anchor": "Topological fine structure of an energy band: A band with a nonzero Chern number cannot be fully localized by weak\ndisorder. There must remain at least one extended state, which ``carries the\nChern number.'' Here we show that a trivial band can behave in a similar way.\nInstead of fully localizing, arbitrarily weak disorder leads to the emergence\nof two sets of extended states, positioned at two different energy intervals,\nwhich carry opposite Chern numbers. Thus, a single trivial band can show the\nsame behavior as two separate Chern bands. We show that this property is\npredicted by a topological invariant called a ``localizer index.'' Even though\nthe band as a whole is trivial as far as the Chern number is concerned, the\nlocalizer index allows access to a topological fine structure. This index\nchanges as a function of energy within the bandwidth of the trivial band,\ncausing nontrivial extended states to appear as soon as disorder is introduced.\nOur work points to a previously overlooked manifestation of topology, which\nimpacts the response of systems to impurities beyond the information included\nin conventional topological invariants.",
        "positive": "Giant spin accumulation in silicon nonlocal spin-transport devices: Although the electrical injection, transport and detection of spins in\nsilicon have been achieved, the induced spin accumulation was much smaller than\nexpected and desired, limiting the potential impact of Si-based spintronic\ndevices. Here, using non-local spin-transport devices with an n-type Si channel\nand Fe/MgO magnetic tunnel contacts, we demonstrate that it is possible to\ncreate a giant spin accumulation in Si, with the spin splitting reaching 13 meV\nat 10 K and 3.5 meV at room temperature. The non-local spin signals are in good\nagreement with a numerical evaluation of spin injection and diffusion that\nexplicitly takes the size of the injector contact into account. The giant spin\naccumulation originates from the large tunnel spin polarization of the Fe/MgO\ncontacts (53 % at 10 K and 18 % at 300 K), and the spin density enhancement\nachieved by using a spin injector with a size comparable to the spin-diffusion\nlength of the Si. The ability to induce a giant spin accumulation enables the\ndevelopment of Si spintronic devices with a large magnetic response."
    },
    {
        "anchor": "Low energy anomalies in electron tunneling through strongly asymmetric\n  Majorana nanowire: Electron transport through Majorana nanowire with strongly asymmetric\ncouplings to normal metal leads is considered. In three terminal geometry\n(electrically grounded nanowire) it is shown that the presence of unbiased\nelectrode restores zero-bias anomaly even for strong Majorana energy splitting.\nFor effectively two-terminal geometry we show that electrical current through\nasymmetric Majorana junction is qualitatively different from the analogous\ncurrent through a resonant (Breit-Wigner) level.",
        "positive": "Interacting multi-channel topological boundary modes in a quantum Hall\n  valley system: Symmetry and topology play key roles in the identification of phases of\nmatter and their properties. Both concepts are central to understanding quantum\nHall ferromagnets (QHFMs), two-dimensional electronic phases with spontaneously\nbroken spin or pseudospin symmetry whose wavefunctions also have topological\nproperties. Domain walls between distinct broken symmetry QHFM phases are\npredicted to host gapless one-dimensional (1D) modes that emerge due to a\ntopological change of the underlying electronic wavefunctions at such\ninterfaces. Although a variety of QHFMs have been identified in different\nmaterials, probing interacting electronic modes at these domain walls has not\nyet been accomplished. Here we use a scanning tunneling microscope (STM) to\ndirectly visualize the spontaneous formation of boundary modes, within a\nsign-changing topological gap, at domain walls between different\nvalley-polarized quantum Hall phases on the surface of bismuth. By changing the\nvalley occupation and the corresponding number of modes at the domain wall, we\ncan realize different regimes where the valley-polarized channels are either\nmetallic or develop a spectroscopic gap. This behavior is a consequence of\nCoulomb interactions constrained by the symmetry-breaking valley flavor, which\ndetermines whether electrons in the topological modes can backscatter, making\nthese channels a unique class of interacting Luttinger liquids."
    },
    {
        "anchor": "Quantum Beating in Ring Conductance: Observation of Spin Chiral States\n  and Berry's phase: Using singly connected rings with a collimating contact to current leads, we\nhave observed the spin quantum beating in the Aharonov-Bohm conductance\noscillations. We demonstrate that the beating is a result of the superposition\nof two independent interference patterns associated with two orthogonal spin\nchiral states arising from intrinsic spin-orbit interactions. Our work provides\nthe conclusive evidence of the spin Berry's phase in the conductance of quantum\nrings.",
        "positive": "Repairing the Surface of InAs-based Topological Heterostructures: Candidate systems for topologically-protected qubits include two-dimensional\nelectron gases (2DEGs) based on heterostructures exhibiting a strong spin-orbit\ninteraction (SOI) and superconductivity via the proximity effect. For InAs- or\nInSb-based materials, the need to form shallow quantum wells to create a\nhard-gapped $p$-wave superconducting state often subjects them to\nfabrication-induced damage, limiting their mobility. Here we examine scattering\nmechanisms in processed InAs 2DEG quantum wells and demonstrate a means of\nincreasing their mobility via repairing the semiconductor-dielectric interface.\nPassivation of charged impurity states with an argon-hydrogen plasma results in\na significant increase in the measured mobility and reduction in its variance\nrelative to untreated samples, up to 45300 cm$^2$/(V s) in a 10 nm deep quantum\nwell."
    },
    {
        "anchor": "Spectroscopic Signatures of Electronic Excitations in Raman Scattering\n  in Thin Films of Rhombohedral Graphite: Rhombohedral graphite features peculiar electronic properties, including\npersistence of low-energy surface bands of a topological nature. Here, we study\nthe contribution of electron-hole excitations towards inelastic light\nscattering in thin films of rhombohedral graphite. We show that, in contrast to\nthe featureless electron-hole contribution towards Raman spectrum of graphitic\nfilms with Bernal stacking, the inelastic light scattering accompanied by\nelectron-hole excitations in crystals with rhombohedral stacking produces\ndistinct features in the Raman signal which can be used both to identify the\nstacking and to determine the number of layers in the film.",
        "positive": "Oscillations of magnetization in topological line-node semimetals: We theoretically investigate the phase of the de Haas - van Alphen\noscillations in topological line-node semimetals. In these semimetals the\nchemical potential of charge carriers can essentially depend on the magnetic\nfield, and this dependence changes the phase of the oscillations as compared to\nthe phase in a three-dimensional metal with a band-contact line. Our results\nelucidate recent experimental data on the Berry phase for certain electron\norbits in ZrSiS, ZrSiTe, and ZrSiSe."
    },
    {
        "anchor": "Biexciton State Energies from Many-Body Perturbation Theory Based on\n  Density Functional Theory Simulation: We develop a method for computing self-energy of a biexciton state in a\nsemiconductor nanostructure using many-body perturbation theory (MBPT) based on\nthe density functional theory (DFT) simulation. We compute energies of\nlow-energy biexciton states composed of singlet excitons in the chiral\nsingle-wall carbon nanotubes (SWCNT), such as (6,2), (6,5) and (10,5). In all\ncases we find a small decrease in the biexciton gap: -0.045 $eV$ in (6,2),\nwhich is 4.59\\% of the non-interacting biexciton gap; -0.041 $eV$ in (6,5),\nwhich is 4.47\\% of the non-interacting gap and -0.036 $eV$ in (10,5), which is\n4.31\\%.",
        "positive": "Electron Transport Properties of Composite Ferroelectrics: We study electron transport in composite ferroelectrics --- materials\nconsisting of metallic grains embedded in a ferroelectric matrix. Due to its\ncomplex tunable morphology the thermodynamic properties of these materials can\nbe essentially different from bulk or thin-film ferroelectrics. We calculate\nthe conductivity of composite ferroelectrics by taking into account the\ninterplay between charge localization, multiple grain boundaries, strong\nCoulomb repulsion, and ferroelectric order parameter. We show that the\nferroelectricity plays a crucial role on the temperature behavior of the\nconductivity in the vicinity of the ferroelectric-paraelectric transition."
    },
    {
        "anchor": "Giant Positive Magnetoresistance in Co@CoO Nanoparticle Arrays: We report the magnetotransport properties of self-assembled Co@CoO\nnanoparticle arrays at temperatures below 100 K. Resistance shows thermally\nactivated behavior that can be fitted by the general expression of R\nexp{(T/T0)^v}. Efros-Shklovskii variable range hopping (v=1/2) and simple\nactivation (hard gap, v=1) dominate the high and low temperature region,\nrespectively, with a strongly temperature-dependent transition regime in\nbetween. A giant positive magnetoresistance of >1,400% is observed at 10K,\nwhich decreases with increasing temperature. The positive MR and most of its\nfeatures can be explained by the Zeeman splitting of the localized states that\nsuppresses the spin dependent hopping paths in the presence of on-site Coulomb\nrepulsion.",
        "positive": "Measurement of Aharonov-Bohm oscillations in mesoscopic metallic rings\n  in the presence of high-frequency electromagnetic fields: We report measurements of Aharonov-Bohm oscillations in normal metal rings in\nthe presence of high frequency electromagnetic fields. The power dependence of\nthe decoherence time scale tau_phi(P) agrees well with the anticipated power\nlaw tau_phi proportional to P^(-1/5) when the field-induced decoherence rate\ntau_ac^(-1) is large compared to the intrinsic decoherence rate tau_o^(-1),\nmeasured in the absence of external fields. As theoretically expected, we\nobserve a decline in field-induced decoherence when tau_ac^(-1)<=tau_o^(-1).\nThe frequency dependence of tau_phi shows a minimum in the oscillation\namplitude at a characteristic frequency, omega_(ac)=1/tau_(o), where tau_(o) is\nevaluated from the oscillation amplitude using the standard mesoscopic theory.\nBoth the suppression in the oscillation amplitude and the concomitant change in\nconductivity allow a direct measurement of the intrinsic decoherence time\nscale."
    },
    {
        "anchor": "Drive Dependence of the Hall Angle for a Sliding Wigner Crystal in a\n  Magnetic Field: We numerically examine the depinning and sliding dynamics of a Wigner crystal\nin the presence of quenched disorder and a magnetic field. In the disorder-free\nlimit, the Wigner crystal Hall angle is independent of crystal velocity, but\nwhen disorder is present, we find that Hall angle starts near zero at the\ndepinning threshold and increases linearly with increasing drive before\nreaching a saturation close to the disorder free value at the highest drives.\nThe drive dependence is the result of a side jump effect produced when the\ncharges move over pinning sites. The magnitude of the side jump is reduced at\nthe higher velocities. The drive dependent Hall angle is robust for a wide\nrange of disorder parameters and should be a generic feature of classical\ncharges driven in the presence of quenched disorder and a magnetic field.",
        "positive": "Long range statistical fluctuations of the crossed Josephson current: We investigate the crossed Josephson effect in a geometry consisting of a\ndouble ferromagnetic bridge between two superconductors, with tunnel\ninterfaces. The crossed Josephson current vanishes on average because the\nAndreev reflected hole does not follow the same sequence of impurities as the\nincoming electron. We show that i) the root mean square of the crossed\nJosephson current distribution is proportional to the square root of the\njunction area; and ii) the coherent coupling mediated by fluctuations is ``long\nrange'' since it decays over the ferromagnet phase coherence length $l_\\phi$,\nlarger than the exchange length. We predict a crossed Josephson current due to\nfluctuations if the length of the ferromagnets is smaller than $l_\\phi$ and\nlarger than the exchange length $\\xi_h$."
    },
    {
        "anchor": "Heat transport and electron cooling in ballistic\n  normal-metal/spin-filter/superconductor junctions: We investigate electron cooling based on a clean\nnormal-metal/spin-filter/superconductor junction. Due to the suppression of the\nAndreev reflection by the spin-filter effect, the cooling power of the system\nis found to be extremely higher than that for conventional\nnormal-metal/nonmagnetic-insulator/superconductor coolers. Therefore we can\nextract large amount of heat from normal metals. Our results strongly indicate\nthe practical usefulness of the spin-filter effect for cooling detectors,\nsensors, and quantum bits.",
        "positive": "Disentangling spin-orbit coupling and local magnetism in a\n  quasi-two-dimensional electron system: Quantum interference between time-reversed electron paths in two dimensions\nleads to the well-known weak localization correction to resistance. If\nspin-orbit coupling is present, the resistance correction is negative, termed\nweak anti-localization (WAL). Here we report the observation of WAL coexisting\nwith exchange coupling between itinerant electrons and localized magnetic\nmoments. We use low-temperature magneto-transport measurements to investigate\nthe quasi-two-dimensional, high-electron-density interface formed between\nSrTiO$_3$ (STO) and the anti-ferromagnetic Mott insulator NdTiO$_3$ (NTO). As\nthe magnetic field angle is gradually tilted away from the sample normal, the\ndata reveals the interplay between strong $k$-cubic Rashba-type spin-orbit\ncoupling and a substantial magnetic exchange interaction from local magnetic\nregions. The resulting quantum corrections to the conduction are in excellent\nagreement with existing models and allow sensitive determination of the small\nmagnetic moments (22 $\\mu_B$ on average), their magnetic anisotropy and mutual\ncoupling strength. This effect is expected to arise in other 2D magnetic\nmaterials systems."
    },
    {
        "anchor": "Emergence of strain-induced moir\u00e9 patterns and pseudo-magnetic field\n  confined states in graphene: Strain-inducing deformations in graphene alter charge distributions and\nprovide a new method to design specific features in the band structure and\ntransport properties. Novel approaches implement engineered substrates to\ninduce specifically targeted strain profiles. Motivated by this technique, we\nstudy the evolution of charge distributions with an increasing number of\nout-of-plane deformations as an example of a finite size periodic substrate. We\nfirst analyze a system of two overlapping deformations and determine the\nquantitative relation between geometrical parameters and features in the local\ndensity of states. We extend the study to sets of 3 and 4 deformations in\nlinear and two-dimensional arrays and observe the emergence of moir\\'e patterns\nthat are more pronounced for a hexagonal cell composed of 7 deformations. A\ncomparison between the induced strain profile and spatial maps of the local\ndensity of states at different energies provides evidence for the existence of\nstates confined by the pseudo-magnetic field in bounded regions, reminiscent of\nquantum dots structures. Due to the presence of these states, the energy level\nscaling to be observed by local probes should exhibit a linear dependence with\nthe pseudo-field, in contrast to the expected scaling of pseudo-Landau levels.",
        "positive": "Rectification of thermal fluctuations in a chaotic cavity heat engine: We investigate the rectification of thermal fluctuations in a mesoscopic\non-chip heat engine. The engine consists of a hot chaotic cavity capacitively\ncoupled to a cold cavity which rectifies the excess noise and generates a\ndirected current. The fluctuation-induced directed current depends on the\nenergy asymmetry of the transmissions of the contacts of the cold cavity to the\nleads and is proportional to the temperature difference. We discuss the maximal\npower output of the heat engine and its efficiency."
    },
    {
        "anchor": "Quantum Size Effects in the Terahertz Nonlinear Response of Metallic\n  Armchair Graphene Nanoribbons: We use time dependent perturbation theory to study quantum size effects on\nthe terahertz nonlinear response of metallic graphene armchair nanoribbons of\nfinite length under an applied electric field. Our work shows that quantization\ndue to the finite length of the nanoribbon, the applied field profile, and the\nbroadening of the graphene spectrum all play a significant role in the\nresulting nonlinear conductances. In certain cases, these effects can\nsignificantly enhance the nonlinearity over that for infinitely-long metallic\narmchair graphene nanoribbon.",
        "positive": "Influence of the Characteristics of the STM-tip on the\n  Electroluminescence Spectra: We analyze the influence of the characteristics of the STM-tip (applied\nvoltage, tip radius) on the electroluminescence spectra from an STM-tip-induced\nquantum dot taking into account the many-body effects. We find that positions\nof electroluminescence peaks, attributed to the electron-hole recombination in\nthe quantum dot, are very sensitive to the shape and size of the confinement\npotential as determined by the tip radius and the applied voltage. A critical\nvalue of the tip radius is found, at which the luminescence peak positions as a\nfunction of the tip radius manifest a transition from decreasing behavior for\nsmaller radii to increasing behavior for larger radii. We find that this\ncritical value of the tip radius is related to the confinement in the lateral\nand normal direction."
    },
    {
        "anchor": "Phase diffusion and fractional Shapiro steps in superconducting quantum\n  point contacts: We study the influence of classical phase diffusion on the fractional Shapiro\nsteps in resistively shunted superconducting quantum point contacts. The\nproblem is mapped onto a Smoluchowski equation with a time dependent potential.\nA numerical solution for the probability density of the phase difference\nbetween the leads gives access to the mean current and the mean voltage across\nthe contact. Analytical solutions are derived in some limiting cases. We find\nthat the effect of temperature is stronger on fractional than on integer steps,\nin accordance with preliminary experimental findings. We further extend the\nanalysis to a more general environment including two resistances and a finite\ncapacitance.",
        "positive": "Zeno and anti-Zeno dynamics in spin-bath models: We investigate the quantum Zeno and anti-Zeno effects in spin bath models:\nthe spin-boson model and a spin-fermion model. We show that the Zeno-anti-Zeno\ntransition is critically controlled by the system-bath coupling parameter, the\nsame parameter that determines spin decoherence rate. We also discuss the\ncrossover in a biased system, at high temperatures, and for a nonequilibrium\nspin-fermion system, manifesting the counteracting roles of electrical bias,\ntemperature, and magnetic field on the spin decoherence rate."
    },
    {
        "anchor": "Thermopower-based hot electron thermometry of helium surface states at\n  1.6 K: We have developed a method to probe the temperature of surface state\nelectrons (SSE) above a superfluid Helium-4 surface using the Seebeck effect.\nIn contrast to previously used SSE thermometry, this technique does not require\ndetailed knowledge of the non-linear mobility. We demonstrate the use of this\nmethod by measuring energy relaxation of SSE at 1.6 K in a microchannel device\nwith $0.6\\:\\mu\\mbox{m}$ deep helium. In this regime, both vapor atom scattering\nand 2-ripplon scattering contribute to energy relaxation to which we compare\nour measurements. We conclude that this technique provides a reliable measure\nof electron temperature while requiring a less detailed understanding of the\nelectron interactions with the environment than previously utilized thermometry\ntechniques.",
        "positive": "Vacuum structure of Toroidal Carbon Nanotubes: Low energy excitations in carbon nanotubes can be described by an effective\nfield theory of two components spinor. It is pointed out that the chiral\nanomaly in 1+1 dimensions should be observed in a metallic toroidal carbon\nnanotube on a planar geometry with varying magnetic field. We propose an\nexperimental setup for studying this quantum effect. We also analyze the vacuum\nstructure of the metallic toroidal carbon nanotube including the Coulomb\ninteractions and discuss some effects of external charges on the vacuum."
    },
    {
        "anchor": "Non-hexagonal-ring defects and structures induced by strain in graphene\n  and in functionalized graphene: We perform {\\textit ab initio} calculations for the strain-induced formation\nof non-hexagonal-ring defects in graphene, graphane (planar CH), and graphenol\n(planar COH). We find that the simplest of such topological defects, the\nStone-Wales defect, acts as a seed for strain-induced dissociation and\nmultiplication of topological defects. Through the application of inhomogeneous\ndeformations to graphene, graphane and graphenol with initially small\nconcentrations of pentagonal and heptagonal rings, we obtain several novel\nstable structures that possess, at the same time, large concentrations of\nnon-hexagonal rings (from fourfold to elevenfold) and small formation energies.",
        "positive": "Interference, Coulomb blockade, and the identification of non-abelian\n  quantum Hall states: We examine the relation between different electronic transport phenomena in a\nFabry-Perot interferometer in the fractional quantum Hall regime. In\nparticular, we study the way these phenomena reflect the statistics of quantum\nHall quasi-particles. For two series of states we examine, one abelian and one\nnon-abelian, we show that the information that may be obtained from\nmeasurements of the lowest order interference pattern in an open Fabry-Perot\ninterferometer is identical to the one that may be obtained from the\ntemperature dependence of Coulomb blockade peaks in a closed interferometer. We\nargue that despite the similarity between the experimental signatures of the\ntwo series of states, interference and Coulomb blockade measurements are likely\nto be able to distinguish between abelian and non-abelian states, due to the\nsensitivity of the abelian states to local perturbations, to which the\nnon-abelian states are insensitive."
    },
    {
        "anchor": "Singular elastic strains and magnetoconductance of suspended graphene: Graphene membranes suspended off electric contacts or other rigid supports\nare prone to elastic strain, which is concentrated at the edges and corners of\nthe samples. Such a strain leads to an algebraically varying effective magnetic\nfield that can reach a few Tesla in sub-micron wide flakes. In the quantum Hall\nregime the interplay of the effective and the physical magnetic fields causes\nbackscattering of the chiral edge channels, which can destroy the quantized\nconductance plateaus.",
        "positive": "Reading the orbital angular momentum of light using plasmonic\n  nanoantennas: Orbital angular momentum of light has recently been recognized as a new\ndegree of freedom to encode information in quantum communication using light\npulses. Methods to extract this information include reversing the process by\nwhich such twisted light was created in the first place or interference with\nother beams. Here, we propose an alternative new way to directly read out the\nextra information encoded in twisted light using plasmonic nanoantennas by con-\nverting the information about the orbital angular momentum of light into\nspectral information using bright and dark modes. Exemplarily considering\nrotation-symmetrical nanorod nanoan- tennas we show that their scattering\ncross-section is sensitive to the value of the orbital angular momentum\ncombined with the polarisation of an incident twisted light beam. Explaining\nthe twist-dependence of the excited modes with a new analytical model our\nresults pave the way to twisted light nanoplasmonics, which is of central\nimportance for future on-chip communication using orbital angular momentum of\nlight."
    },
    {
        "anchor": "Roses in the Nonperturbative Current Response of Artificial Crystals: In two-dimensional artificial crystals with large real-space periodicity, the\nnonlinear current response to a large applied electric field can feature a\nstrong angular dependence, which encodes information about the band dispersion\nand Berry curvature of isolated electronic Bloch minibands. Within the\nrelaxation-time approximation, we obtain analytic expressions up to infinite\norder in the driving field for the current in a band-projected theory with\ntime-reversal and trigonal symmetry. For a fixed field strength, the dependence\nof the current on the direction of the applied field is given by rose curves\nwhose petal structure is symmetry constrained and is obtained from an expansion\nin real-space translation vectors. We illustrate our theory with calculations\non periodically-buckled graphene and twisted double bilayer graphene, wherein\nthe discussed physics can be accessed at experimentally-relevant field\nstrengths.",
        "positive": "Elastic properties of graphene flakes: boundary effects and lattice\n  vibrations: We present a calculation of the free energy, the surface free energy and the\nelastic constants (\"Lam'e parameters\" i.e, Poisson ratio, Young's modulus) of\ngraphene flakes on the level of the density functional theory employing\ndifferent standard functionals. We observe that the Lam'e parameters in small\nflakes can differ from the bulk values by 30% for hydrogenated zig-zag edges.\nThe change results from the edge of the flake that compresses the interior.\nWhen including the vibrational zero point motion, we detect a decrease in the\nbending rigidity by ~26%. This correction is depending on the flake size, N,\nbecause the vibrational frequencies flow with growing N due to the release of\nthe edge induced compression. We calculate Grueneisen parameters and find good\nagreement with previous authors."
    },
    {
        "anchor": "Spin accumulation in ballistic Rashba bar: We propose an analytic model to study intrinsic spin polarization effect in a\nballistic Rashba bar with two semi-infinite leads. The wave functions expanded\nwith plane waves in Rashba bar are required to satisfy boundary conditions at\nboth longitudinal and transverse interfaces. We find out-of-plane spin Hall\naccumulation effect can be induced in the Rashba bar even with large dimensions\nby injecting unpolarized current from the lead. The longitudinal in-plane spin\nHall effect, however, becomes obscure in large-size sample. An interesting\ndirection-flipping of the out-of-plane spin accumulation is predicted by\naltering the Rashba coupling strength.",
        "positive": "Shot noise in a harmonically driven ballistic graphene transistor: We study time-dependent electron transport and quantum noise in a ballistic\ngraphene field effect transistor driven by an ac gate potential. The non-linear\nresponse to the ac signal is computed through Floquet theory for scattering\nstates and Landauer-B\\\"uttiker theory for charge current and its fluctuations.\nPhoton-assisted excitation of a quasibound state in the top-gate barrier leads\nto resonances in transmission that strongly influence the noise properties. For\nstrong doping of graphene under source and drain contacts, when electrons are\ntransmitted through the channel via evanescent waves, the resonance leads to a\nsubstantial suppression of noise. The Fano factor is then reduced well below\nthe pseudo-diffusive value, $F<1/3$, also for strong ac drive. The good\nsignal-to-noise ratio (small Fano factor) on resonance suggests that the device\nis a good candidate for high-frequency (THz) radiation detection. We show\nanalytically that Klein tunneling (total suppression of back-reflection)\npersists for perpendicular incidence also when the barrier is driven\nharmonically. Although the transmission is inelastic and distributed among\nsideband energies, a sum rule leads to total suppression of shot noise."
    },
    {
        "anchor": "Near-unity quantum yield from carbon nanotube excitons coupled to\n  plasmonic nanocavities: Single-walled carbon nanotubes (SWCNTs) are promising absorbers and emitters\nto enable novel photonic and optoelectronic applications but are also known to\nseverely suffer from low optical quantum yields. Here we demonstrate SWCNTs\nexcitons coupled to plasmonic nanocavities reaching deeply into the Purcell\nregime with FP=234 (average FP=76), near unity quantum yields of 70% (average\n41%), and a photon emission rate of 1.7 MHz into the first lens. The measured\nultra-narrow exciton linewidth (18 micro eV) implies furthermore generation of\nindistinguishable single photons from a SWCNT. To demonstrate utility beyond\nquantum light sources we show that nanocavity-coupled SWCNTs perform as\nsingle-molecule thermometers detecting plasmonically induced heat (Delta\nT=150K) in a unique interplay of excitons, phonons, and plasmons at the\nnanoscale.",
        "positive": "A condition for first order phase transitions in quantum mechanical\n  tunneling models: A criterion is derived for the determination of parameter domains of first\norder phase transitions in quantum mechanical tunneling models. The criterion\nis tested by application to various models, in particular to some which have\nbeen used recently to explore spin tunneling in macroscopic particles. In each\ncase agreement is found with previously heuristically determined domains."
    },
    {
        "anchor": "Terahertz quantum cascade lasers with thin resonant-phonon depopulation\n  active regions and surface-plasmon waveguides: We report three-well, resonant-phonon depopulation terahertz quantum cascade\nlasers with semi-insulating surface-plasmon waveguides and reduced active\nregion (AR) thicknesses. Devices with thicknesses of 10, 7.5, 6, and 5 {\\mu}m\nare compared in terms of threshold current density, maximum operating\ntemperature, output power and AR temperature. Thinner ARs are technologically\nless demanding for epitaxial growth and result in reduced electrical heating of\ndevices. However, it is found that 7.5-{\\mu}m-thick devices give the lowest\nelectrical power densities at threshold, as they represent the optimal\ntrade-off between low electrical resistance and low threshold gain.",
        "positive": "Quantum Percolation Transition from Graphene to Graphane: Graph\n  Theoretical Approach: Graphane is obtained by perfectly hydrogenating graphene. There exists an\nintermediate material, partially hydrogenated graphene (which we call\n\\textit{hydrographene}), interpolating from pure graphene to pure graphane. It\nhas various intriguing electronic and magnetic properties. We investigate a\nmetal-insulator transition, employing a quantum-site percolation model together\nwith a graph theoretical approach. Hydrographene is an exceptional case in\nwhich electronic properties cannot be determined solely by the density of\nstates at the Fermi energy. Though there are plenty of zero energy state in\nwide range of hydrogenation density, most of them are insulating states. We\nalso demonstrate that it shows a bulk ferromagnetic property based on the Lieb\ntheory."
    },
    {
        "anchor": "Efficient steady state solver for the hierarchical equations of motion\n  approach: Formulation and application to charge transport through nanosystems: An iterative approach is introduced, which allows the efficient solution of\nthe hierarchical equations of motion (HEOM) for the steady state of open\nquantum systems. The approach combines the method of matrix equations with an\nefficient preconditioning technique to reduce the numerical effort of solving\nthe HEOM. Illustrative applications to simulate nonequilibrium charge transport\nin single-molecule junctions demonstrate the performance of the method.",
        "positive": "Geometrical dependence of decoherence by electronic interactions in a\n  GaAs/GaAlAs square network: We investigate weak localization in metallic networks etched in a two\ndimensional electron gas between $25\\:$mK and $750\\:$mK when electron-electron\n(e-e) interaction is the dominant phase breaking mechanism. We show that, at\nthe highest temperatures, the contributions arising from trajectories that wind\naround the rings and trajectories that do not are governed by two different\nlength scales. This is achieved by analyzing separately the envelope and the\noscillating part of the magnetoconductance. For $T\\gtrsim0.3\\:$K we find\n$\\Lphi^\\mathrm{env}\\propto{T}^{-1/3}$ for the envelope, and\n$\\Lphi^\\mathrm{osc}\\propto{T}^{-1/2}$ for the oscillations, in agreement with\nthe prediction for a single ring \\cite{LudMir04,TexMon05}. This is the first\nexperimental confirmation of the geometry dependence of decoherence due to e-e\ninteraction."
    },
    {
        "anchor": "RKKY Interaction in Graphene from Lattice Green's Function: We study the exchange interaction $J$ between two magnetic impurities in\ngraphene (the RKKY interaction) by directly computing the lattice Green's\nfunction for the tight-binding band structure for the honeycomb lattice. The\nmethod allows us to compute $J$ numerically for much larger distances than can\nbe handled by finite-lattice calculations as well as for small distances. %\navoids the use of a cutoff function often invoked in the literature to curtail\nthe diverging contributions from the linear bands and yields results that are\nvalid for all distances. In addition, we rederive the analytical long-distance\nbehavior of $J$ for linearly dispersive bands and find corrections to the\noscillatory factor that were previously missed in the literature. The main\nfeatures of the RKKY interaction in graphene are that unlike the $J \\propto\n(2k_FR)^{-2} \\sin (2k_FR) $ behavior of an ordinary 2D metal in the\nlong-distance limit, $J$ in graphene falls off as $1/R^3$, shows the $1 + \\cos\n((K-K').R)$-type oscillations with additional phase factors depending on the\ndirection, and exhibits a ferromagnetic interaction for moments on the same\nsublattice and an antiferromagnetic interaction for moments on the opposite\nsublattices as required by particle-hole symmetry. The computed $J$ with the\nfull band structure agrees with our analytical results in the long-distance\nlimit including the oscillatory factors with the additional phases.",
        "positive": "Geometrically constrained Skyrmions: Skyrmions are chiral swirling magnetization structures with nanoscale size.\nThese structures have attracted considerable attention due to their topological\nstability and promising applicability in nanodevices, since they can be\ndisplaced with spin-polarized currents. However, for the comprehensive\nimplementation of skyrmions in devices, it is imperative to also attain control\nover their geometrical position. Here we show that, through thickness\nmodulations introduced in the host material, it is possible to constrain\nthree-dimensional skyrmions to desired regions. We investigate skyrmion\nstructures in rectangular FeGe platelets with micromagnetic finite element\nelement simulations. First, we establish a phase diagram of the minimum-energy\nmagnetic state as a function of the external magnetic field strength and the\nfilm thickness. Using this understanding, we generate preferential sites for\nskyrmions in the material by introducing dot-like \"pockets\" of reduced film\nthickness. We show that these pockets can serve as pinning centers for the\nskyrmions, thus making it possible to obtain a geometric control of the\nskyrmion position. This control allows stabilizing skyrmions at positions and\nin configurations that they would otherwise not attain. Our findings may have\nimplications for technological applications in which skyrmions are used as\nunits of information that are displaced along racetrack-type shift register\ndevices."
    },
    {
        "anchor": "Spin-selective strong light-matter coupling in a 2D hole gas-microcavity\n  system: The interplay between time-reversal symmetry breaking and strong light-matter\ncoupling in 2D gases brings intriguing aspects to polariton physics. This\ncombination can lead to polarization/spin selective light-matter interaction in\nthe strong coupling regime. In this work, we report such a selective strong\nlight-matter interaction by harnessing a 2D gas in the quantum Hall regime\ncoupled to a microcavity. Specifically, we demonstrate circular-polarization\ndependence of the vacuum Rabi splitting, as a function of magnetic field and\nhole density. We provide a quantitative understanding of the phenomenon by\nmodeling the coupling of optical transitions between Landau levels to the\nmicrocavity. This method introduces a control tool over the spin degree of\nfreedom in polaritonic semiconductor systems, paving the way for new\nexperimental possibilities in light-matter hybrids.",
        "positive": "Dynamics of ripple formation on silicon surfaces by ultrashort laser\n  pulses in sub-ablation conditions: An investigation of ultrashort pulsed laser induced surface modification due\nto conditions that result in a superheated melted liquid layer and material\nevaporation are considered. To describe the surface modification occurring\nafter cooling and resolidification of the melted layer and understand the\nunderlying physical fundamental mechanisms, a unified model is presented to\naccount for crater and subwavelength ripple formation based on a synergy of\nelectron excitation and capillary waves solidification. The proposed\ntheoretical framework aims to address the laser-material interaction in\nsub-ablation conditions and thus minimal mass removal in combination with a\nhydrodynamics-based scenario of the crater creation and ripple formation\nfollowing surface irradiation with single and multiple pulses, respectively.\nThe development of the periodic structures is attributed to the interference of\nthe incident wave with a surface plasmon wave. Details of the surface\nmorphology attained are elaborated as a function of the imposed conditions and\nresults are tested against experimental data."
    },
    {
        "anchor": "Different ways of looking at the force between two nano crystals: The potential of mean force (PMF) between two nano crystals (NCs) represents\nan effective interaction potential that can be used to study the assembly of\nNCs to various superstructures. For a given temperature, the effective\ninteraction is obtained best from molecular dynamics simulations. Based on a\ndensity functional approach, this study proposes three methods of predicting\nthe PMF for any temperature based on a single molecular dynamics simulation for\none temperature. The three methods construct the PMF by considering the ligands\nas an ideal gas, as hard-sphere chains, or as Lennard-Jones interaction sites.\nTo apply this methodology, the density of the interaction centers must be\nextracted from the simulation data. For the ideal gas model, a straightforward\nsampling procedure with a fixed lattice in space leads to free energies that\nare too large in order to consistently explain the simulation data for\ndifferent temperatures. Naive sampling does not account for the small momenta\nadded to the NCs when coupled to a thermostat. A method is proposed that\ncorrects for the unphysical steps during the simulation. The ideal gas\ncontribution computed for the corrected density is significantly smaller than\nthe one obtained from naive sampling and can thus explain the temperature\ndependence of the PMF correctly. For the hard-sphere chain model, where a\nweighted density is used, the correction of the particle density is not\nessential. However, the PMF calculated based on the corrected density confirms\nour approach. All three models predict PMF curves in very good agreement with\nsimulation results, but they differ in the number of input parameters and the\ncomputational effort. Based on the modeling results, we predict the existence\nof an additional attractive force at small distances of the NCs - a depletion\nforce.",
        "positive": "Dissipation and phase transitions in superconducting circuits coupled to\n  normal metal resistor: The Caldeira-Leggett model is the most commonly accepted approach to describe\ndissipation in superconducting circuits. But the existence of the resulting\nSchmidt-Bulgadaev (SB) transition is still heavily debated. We study a\nmicroscopically motivated model for a charge qubit electrically and\ncapacitively coupled to a normal metal, with seemingly minute changes to\nCaldeira-Leggett - but a significantly different phase diagram. While this\nmodel still hosts an SB transition in the transmon regime, the critical\nparameter is largely independent of the metal's resistivity. In the opposite\nCooper pair box regime, the system now resembles an anisotropic Kondo model\nwith the two degenerate charge states as the pseudo-spin. Here, however, a\ntransition to a ferromagnetic phase is not possible for regular electrostatic\ninteractions. We further argue that some of the guiding principles of our work\nare transferable to resistors made of bosonic transmission lines."
    },
    {
        "anchor": "Intervalley scattering in MoS$_2$ imaged by two-photon photoemission\n  with a high-harmonic probe: We report on the direct mapping of electron transfer in the momentum space of\nbulk MoS$_2$ by means of time- and angle-resolved two-photon photoemission with\na high-harmonic probe. For this purpose, we have combined a high-repetition\nrate high-harmonic source with tunable femtosecond pump pulses and a 3D ($k_x,\nk_y, E$) electron spectrometer. We show that optical excitation slightly above\nthe A exciton resonance results in an immediate occupation of the conduction\nband at $\\overline{K}$ followed by an ultrafast transfer ($< 50$~fs) to the\nconduction band minimum at $\\overline{\\Sigma}$. Both signals, at $\\overline{K}$\nand $\\overline{\\Sigma}$, do not vanish over the observed period of 400~fs. The\ntechnique described here enables direct access to the charge transfer dynamics\nin $k$-space and allows the study of decay times and decay channels in various\nsystems with dependence on the excess energy or helicity of the excitation.",
        "positive": "Nonreciprocal nano-optics with spin-waves in synthetic antiferromagnets: Integrated optically-inspired wave-based processing is envisioned to\noutperform digital architectures in specific tasks, such as image processing\nand speech recognition. In this view, spin-waves represent a promising route\ndue to their nanoscale wavelength in the GHz frequency range and rich\nphenomenology. Here, we realize a versatile optically-inspired platform using\nspin-waves, demonstrating the wavefront engineering, focusing, and robust\ninterference of spin-waves with nanoscale wavelength. In particular, we use\nmagnonic nanoantennas based on tailored spin-textures for launching spatially\nshaped coherent wavefronts, diffraction-limited spin-wave beams, and generating\nrobust multi-beam interference patterns, which spatially extend for several\ntimes the spin-wave wavelength. Furthermore, we show that intriguing features,\nsuch as resilience to back-reflection, naturally arise from the spin-wave\nnonreciprocity in synthetic antiferromagnets, preserving the high quality of\nthe interference patterns from spurious counterpropagating modes. This work\nrepresents a fundamental step towards the realization of nanoscale\noptically-inspired devices based on spin-waves."
    },
    {
        "anchor": "Spin-polarized currents in corrugated graphene nanoribbons: We investigate the production of spin-polarized currents in corrugated\ngraphene nanoribbons. Such corrugations are modeled as multiple regions with\nRashba spin-orbit interactions, where concave and convex curvatures are treated\nas Rashba regions with opposite signs. Numerical examples for different\nseparated Rashba-zone geometries calculated within the tight-binding\napproximation are provided. Remarkably, the spin-polarized current in a system\nwith several Rashba areas can be enhanced with respect to the case with a\nsingle Rashba part of the same total area. The enhancement is larger for\nconfigurations with multiple regions with the same Rashba sign. This indicates\nthat the increase of the spin polarization is due to the scattering of the\nelectrons traversing regions with and without Rashba interaction. Additionally,\nwe relate the appearance of the spin-polarized currents to novel symmetry\nrelations between the spin-dependent conductances. These symmetries turn out to\nbe a combination of different symmetry operations in real and spin spaces, as\nthose occurring in non-planar systems like carbon nanotubes. Our results show\nthat two-dimensional devices with Rashba spin-orbit interaction can be used as\nexcellent spintronic devices in an all-electrical or mechanical setup.",
        "positive": "Nanoscale Magnetic Heat Pumps and Engines: We present the linear response matrix for a sliding domain wall in a\nrotatable magnetic nanowire, which is driven out of equilibrium by temperature\nand voltage bias, mechanical torque, and magnetic field. An expression for\nheat-current induced domain wall motion is derived. Application of Onsager's\nreciprocity relation leads to a unified description of the Barnett and\nEinstein-de Haas effects as well as spin-dependent thermoelectric properties.\nWe envisage various heat pumps and engines, such as coolers driven by magnetic\nfields or mechanical rotation as well as nanoscale motors that convert\ntemperature gradients into useful work. All parameters (with the exception of\nmechanical friction) can be computed microscopically by the scattering theory\nof transport."
    },
    {
        "anchor": "Probing Bogoliubov quasiparticles in superfluid $^3$He with a\n  'vibrating-wire like' MEMS device: We have measured the interaction between superfluid $^3$He-B and a\nmicro-machined goalpost-shaped device at temperatures below $0.2\\,T_c$. The\nmeasured damping follows well the theory developed for vibrating wires, in\nwhich the Andreev reflection of quasiparticles in the flow field around the\nmoving structure leads to a nonlinear frictional force. At low velocities the\ndamping force is proportional to velocity while it tends to saturate for larger\nexcitations. Above a velocity of 2.6$\\,$mms$^{-1}$ the damping abruptly\nincreases, which is interpreted in terms of Cooper-pair breaking.\nInterestingly, this critical velocity is significantly lower than reported with\nother mechanical probes immersed in superfluid $^3$He. Furthermore, we report\non a nonlinear resonance shape for large motion amplitudes that we interpret as\nan inertial effect due to quasiparticle friction, but other mechanisms could\npossibly be invoked as well.",
        "positive": "Selection rules of twistronic angles in 2D material flakes via\n  dislocation theory: Interlayer rotation angle couples strongly to the electronic states of\ntwisted van der Waals layers. However, not every angle is energetically\nfavorable. Recent experiments on rotation-tunable electronics reveal the\nexistence of a discrete set of angles at which the rotation-tunable electronics\nassume the most stable configurations. Nevertheless, a quantitative map for\nlocating these intrinsically preferred twist angles in twisted bilayer system\nhas not been available, posing challenges for the on-demand design of twisted\nelectronics that are intrinsically stable at desired twist angles. Here we\nreveal a simple mapping between intrinsically preferred twist angles and\ngeometry of the twisted bilayer system, in the form of geometric scaling laws\nfor a wide range of intrinsically preferred twist angles as a function of only\ngeometric parameters of the rotating flake on a supporting layer. We reveal\nthese scaling laws for triangular and hexagonal flakes since they frequently\nappear in chemical vapor deposition growth. We also present a general method\nfor handling arbitrary flake geometry. Such dimensionless scaling laws possess\nuniversality for all kinds of two-dimensional material bilayer systems,\nproviding abundant opportunities for the on-demand design of intrinsic\n\"twistronics\". For example, the set of increasing magic-sizes that\nintrinsically prefers zero-approaching sequence of multiple magic-angles in\nbilayer graphene system can be revealed."
    },
    {
        "anchor": "Energy Transfer into Period-Tripled States in Coupled Electromechanical\n  Modes at Internal Resonance: Efficient energy transfer often occurs between oscillation modes in a\nresonator when they are tuned to internal resonance. We design the\neigenfrequencies of two vibrational modes of an electromechanical resonator to\nbe close to a ratio of 3:1 and demonstrate that the energy supplied to the\nupper mode can be controllably transferred to the lower mode. With the lower\nmode vibrating with a period tripled that of the upper mode, the discrete\ntime-translation symmetry imposed by the periodic drive is broken. The lower\nmode settles into one of three stable period-tripled states with different\nphases. This channel for energy transfer from the upper mode can be turned on\nor off without changing system parameters. When the upper mode itself becomes\nmultistable under strong resonant or parametric drive, additional sets of\ncoexisting period-tripled states emerge in the lower mode. In the latter case,\nwe measure a total of 6 coexisting vibration states with identical amplitude\nbut phases differing by $\\pi$/3. Excitation of coexisting states with three\ndifferent phases could open new opportunities in designing mechanical memory\nbased on ternary logic. Coupled resonators with period-tripled states can also\nbe used to model complex interacting systems with spin equals one.",
        "positive": "Anomalous conductance scaling in Weyl semimetal NbAs: Protected surface states arising from non-trivial bandstructure topology in\nsemimetals can potentially enable new device functionalities in compute,\nmemory, interconnect, sensing, and communication. This necessitates a\nfundamental understanding of surface-state transport in nanoscale topological\nsemimetals. Here, we investigate quantum transport in a prototypical\ntopological semimetal NbAs to evaluate the potential of this class of materials\nfor beyond-Cu interconnects in highly-scaled integrated circuits. Using density\nfunctional theory (DFT) coupled with non-equilibrium Green's function (NEGF)\ncalculations, we shows that the resistance-area $RA$ product in NbAs films\ndecreases with decreasing thickness at the nanometer scale, in contrast to a\nnearly constant $RA$ product in ideal Cu films. This anomalous scaling\noriginates from the disproportionately large number of surface conduction\nstates which dominate the ballistic conductance by up to 70$\\%$ in NbAs thin\nfilms. We also show that this favorable $RA$ scaling persists even in the\npresence of surface defects, in contrast to $RA$ sharply increasing with\nreducing thickness for films of conventional metals, such as Cu, in the\npresence of surface defects. These results underscore the promise of\ntopological semimetals like NbAs as future back-end-of-line (BEOL) interconnect\nmetals."
    },
    {
        "anchor": "Probing the Nuclear Spin-Lattice Relaxation Time at the Nanoscale: Nuclear spin-lattice relaxation times are measured on copper using magnetic\nresonance force microscopy performed at temperatures down to 42 mK. The low\ntemperature is verified by comparison with the Korringa relation. Measuring\nspin-lattice relaxation times locally at very low temperatures opens up the\npossibility to measure the magnetic properties of inhomogeneous electron\nsystems realized in oxide interfaces, topological insulators and other strongly\ncorrelated electron systems such as high-Tc superconductors.",
        "positive": "Fluctuation-driven thermal transport in graphene double-layers at charge\n  neutrality: We develop a theory of fluctuation-driven phenomena in thermal transport in\ngraphene double-layers. We work in the regime of electron hydrodynamics and\nfocus on the double charge neutrality point. Although at the neutrality point\ncharge transport is decoupled from the hydrodynamic flow, thermal fluctuations\nof electron density cause both drag and heat transfer between the layers. The\nthermal transport in the bilayer system is governed by these two phenomena. We\nexpress the drag friction coefficient and the interlayer thermal conductivity\nin terms of the interlayer distance and the intrinsic conductivity of the\nelectron liquid. We then obtain the thermal conductance matrix and determine\nthe spatial dependence of the hydrodynamic velocity and temperature in the\nsystem. For shorter system the thermal drag resistance is determined by drag.\nIn longer systems the situation of perfect thermal drag is realized, in which\nthe hydrodynamic velocities in both layers become equal in the interior of the\nsystems. Estimates are given for the monolayer and bilayer graphene devices.\nThe predictions of our theory can be tested by the high-resolution thermal\nimaging and Johnson-Nyquist nonlocal noise thermometry."
    },
    {
        "anchor": "Time delay in a disordered topological system: The discovery of topological insulators has opened new prospects for robust\nsignal transport for electronic, phononic, and photonic devices. Though\ntransport of topological protected edge states is robust to disorder, large\nfluctuations and lengthened average delay time are observed. Here, we consider\na quasi-1d system following the Haldane model and generalize the idea of\neigenchannel time delay to the topological system. Eigenchannel time delay\nindicates the excited density of states for the configuration and relates to\nthe intensity integral inside the system. Taking advantage of this property, we\npoint out a practical way to extract the central frequency and linewidth of\nlocalized modes excited in the topological system. This work links the\nfluctuation of time delay to the strength of disorder and discusses the scaling\nof time delay.",
        "positive": "Nonlocal effects in the shot noise of diffusive superconductor -\n  normal-metal systems: A cross-shaped diffusive system with two superconducting and two normal\nelectrodes is considered. A voltage $eV < \\Delta$ is applied between the normal\nleads. Even in the absence of average current through the superconducting\nelectrodes their presence increases the shot noise at the normal electrodes and\ndoubles it in the case of a strong coupling to the superconductors. The\nnonequilibrium noise at the superconducting electrodes remains finite even in\nthe case of a vanishingly small transport current due to the absence of energy\ntransfer into the superconductors. This noise is suppressed by\nelectron-electron scattering at sufficiently high voltages."
    },
    {
        "anchor": "Antiresonances in Molecular Wires: We present analytic and numerical studies based on Landauer theory of\nconductance antiresonances of molecular wires. Our analytic treatment is a\nsolution of the Lippmann-Schwinger equation for the wire that includes the\neffects of the non-orthogonality of the atomic orbitals on different atoms\nexactly. The problem of non-orthogonality is treated by solving the transport\nproblem in a new Hilbert space which is spanned by an orthogonal basis. An\nexpression is derived for the energies at which antiresonances should occur for\na molecular wire connected to a pair of single-channel 1D leads. From this\nexpression we identify two distinct mechanisms that give rise to antiresonances\nunder different circumstances. The exact treatment of non-orthogonality in the\ntheory is found to be necessary to obtain reliable results. Our numerical\nsimulations extend this work to multichannel leads and to molecular wires\nconnected to 3D metallic nanocontacts. They demonstrate that our analytic\nresults also provide a good description of these more complicated systems\nprovided that certain well-defined conditions are met. These calculations\nsuggest that antiresonances should be experimentally observable in the\ndifferential conductance of molecular wires of certain types.",
        "positive": "Crosstalk analysis for simultaneously driven two-qubit gates in spin\n  qubit arrays: One of the challenges when scaling up semiconductor-based quantum processors\nconsists in the presence of crosstalk errors caused by control operations on\nneighboring qubits. In previous work, crosstalk in spin qubit arrays has been\ninvestigated for non-driven single qubits near individually driven quantum\ngates and for two simultaneously driven single-qubit gates. Nevertheless,\nsimultaneous gates are not restricted to single-qubit operations but also\ninclude frequently used two-qubit gates such as the CNOT gate. We analyse the\nimpact of crosstalk drives on qubit operations, such as the CNOT and CPHASE\ngates. We investigate the case of parallel $Y$ and CNOT gates, and we also\nconsider a two-dimensional arrangement of two parallel CNOT gates and find\nunavoidable crosstalk. To minimize crosstalk errors, we develop appropriate\ncontrol protocols."
    },
    {
        "anchor": "Dimension dependence of negative differential thermal resistance in\n  graphene nanoribbons: Negative differential thermal resistance (NDTR) in approximate graphene\nnanoribbons (GNRs) is investigated from one dimension to three dimensions by\nusing classical molecular dynamics method. For single-layer GNRs, NDTR can not\nbe observed for very narrow GNRs (one dimension), NDTR appears when the width\nof GNRs increases (two dimensions). However, NDTR disappears gradually on\nfurther increasing the width. For multiple-layer GNRs, when the number of the\nlayers increases, GNRs becomes from two-dimensional system to three-dimensional\nsystem, NDTR regime reduces and eventually disappears. In addition, when the\nlength of GNRs increases, NDTR regime also reduces and vanishes in the\nthermodynamic limit. These effects may be useful for designing thermal devices\nwhere NDTR plays an important role.",
        "positive": "Notes on Decoherence at Absolute Zero: The problem of electron decoherence at low temperature is analyzed from the\nperspective of recent experiments on decoherence rate measurement and on\nrelated localization phenomena in low-dimensional systems. Importance of\ndecoherence at zero temperature, perhaps induced by quantum fluctuations, is\nput in a broader context."
    },
    {
        "anchor": "Theory of Domain Wall Dynamics under Current: Microscopic theory of domain wall dynamics under electric current is\nreviewed. Domain wall is treated as rigid and planar. The spin-transfer torque\nand forces on the wall are derived based on the $s$-$d$ exchange interaction\nbetween localized spins and conduction electrons, treating non-adiabaticity\nexpressed by the gauge field perturbatively. Effect of spin relaxation is also\nstudied.",
        "positive": "Chaotic Spin-Wave Solitons in Magnetic Film Feedback Rings: Chaotic spin-wave solitons in magnetic film active feedback rings were\nobserved for the first time. At some ring gain level, one observes the\nself-generation of a single spin-wave soliton pulse in the ring. When the pulse\ncirculates in the ring, its amplitude varies chaotically with time. Numerical\nsimulations based on a gain-loss nonlinear Schr\\\"odinger equation reproduce the\nobserved responses."
    },
    {
        "anchor": "InSb Nanowires with Built-In GaxIn1-xSb Tunnel Barriers for Majorana\n  Devices: Majorana zero modes (MZMs), prime candidates for topological quantum bits,\nare detected as zero bias conductance peaks (ZBPs) in tunneling spectroscopy\nmeasurements. Implementation of a narrow and high tunnel barrier in the next\ngeneration of Majorana devices can help to achieve the theoretically predicted\nquantized height of the ZBP. We propose a material-oriented approach to\nengineer a sharp and narrow tunnel barrier by synthesizing a thin axial segment\nof GaxIn1-xSb within an InSb nanowire. By varying the precursor molar fraction\nand the growth time, we accurately control the composition and the length of\nthe barriers. The height and the width of the GaxIn1-xSb tunnel barrier are\nextracted from the Wentzel-Kramers-Brillouin (WKB)-fits to the experimental I-V\ntraces.",
        "positive": "The Josephson heat interferometer: The Josephson effect represents perhaps the prototype of macroscopic phase\ncoherence and is at the basis of the most widespread interferometer, i.e., the\nsuperconducting quantum interference device (SQUID). Yet, in analogy to\nelectric interference, Maki and Griffin predicted in 1965 that thermal current\nflowing through a temperature-biased Josephson tunnel junction is a stationary\nperiodic function of the quantum phase difference between the superconductors.\nThe interplay between quasiparticles and Cooper pairs condensate is at the\norigin of such phase-dependent heat current, and is unique to Josephson\njunctions. In this scenario, a temperature-biased SQUID would allow heat\ncurrents to interfere thus implementing the thermal version of the electric\nJosephson interferometer. The dissipative character of heat flux makes this\ncoherent phenomenon not less extraordinary than its electric (non-dissipative)\ncounterpart. Albeit weird, this striking effect has never been demonstrated so\nfar. Here we report the first experimental realization of a heat\ninterferometer. We investigate heat exchange between two normal metal\nelectrodes kept at different temperatures and tunnel-coupled to each other\nthrough a thermal `modulator' in the form of a DC-SQUID. Heat transport in the\nsystem is found to be phase dependent, in agreement with the original\nprediction. With our design the Josephson heat interferometer yields\nmagnetic-flux-dependent temperature oscillations of amplitude up to ~21 mK, and\nprovides a flux-to-temperature transfer coefficient exceeding ~ 60mK/Phi_0 at\n235 mK [Phi_0 2* 10^(-15) Wb is the flux quantum]. Besides offering remarkable\ninsight into thermal transport in Josephson junctions, our results represent a\nsignificant step toward phase-coherent mastering of heat in solid-state\nnanocircuits, and pave the way to the design of novel-concept coherent\ncaloritronic devices."
    },
    {
        "anchor": "Floquet engineering of edge states in the presence of staggered\n  potential and interactions: We study the effects of a periodically driven electric field applied to a\nvariety of tight-binding models in one dimension. We first consider a\nnon-interacting system with or without a staggered on-site potential, and we\nfind that that periodic driving can generate states localized completely or\npartially near the ends of a finite-sized system. Depending on the system\nparameters, such states have Floquet eigenvalues lying either outside or inside\nthe continuum of eigenvalues of the bulk states; only in the former case we\nfind that these states are completely localized at the ends and are true edge\nstates. We then consider a system of two bosonic particles which have an\non-site Hubbard interaction and show that a periodically driven electric field\ncan generate two-particle states which are localized at the ends of the system.\nWe show that many of these effects can be understood using a Floquet\nperturbation theory which is valid in the limit of large staggered potential or\nlarge interaction strength. Some of these effects can also be understood\nqualitatively by considering time-independent Hamiltonians which have a\npotential at the sites at the edges; Hamiltonians of these kind effectively\nappear in a Floquet-Magnus analysis of the driven problem. Finally, we discuss\nhow the edge states produced by periodic driving of a non-interacting system of\nfermions can be detected by measuring the differential conductance of the\nsystem.",
        "positive": "Mechanism of the Resonant Enhancement of Electron Drift in Nanometre\n  Semiconductor Superlattices Subjected to Electric and Inclined Magnetic\n  Fields: We address the increase of electron drift velocity that arises in\nsemiconductor superlattices (SLs) subjected to constant electric and magnetic\nfields. It occurs if the magnetic field possesses nonzero components both along\nand perpendicular to the SL axis and the Bloch oscillations along the SL axis\nbecome resonant with cyclotron rotation in the transverse plane. It is a\nphenomenon of considerable interest, so that it is important to understand the\nunderlying mechanism. In an earlier Letter (Phys. Rev. Lett. 114, 166802\n(2015)) we showed that, contrary to a general belief that drift enhancement\noccurs through chaotic diffusion along a stochastic web (SW) within\nsemiclassical collisionless dynamics, the phenomenon actually arises through a\nnon-chaotic mechanism. In fact, any chaos that occurs tends to reduce the\ndrift. We now provide fuller details, elucidating the mechanism in physical\nterms, and extending the investigation. In particular, we: (i) demonstrate that\npronounced drift enhancement can still occur even in the complete absence of an\nSW; (ii) show that, where an SW does exist and its characteristic slow dynamics\ncomes into play, it suppresses the drift enhancement even before strong chaos\nis manifested; (iii) generalize our theory for non-small temperature, showing\nthat heating does not affect the enhancement mechanism and accounting for some\nearlier numerical observations; (iv) demonstrate that certain analytic results\nreported previously are incorrect; (v) provide an extended critical review of\nthe subject and closely related issues; and (vi) discuss some challenging\nproblems for the future."
    },
    {
        "anchor": "Fermi level pinning can determine polarity in semiconductor nanorods: First-principles calculations of polar semiconductor nanorods reveal that\ntheir dipole moments are strongly influenced by Fermi level pinning. The Fermi\nlevel for an isolated nanorod is found to coincide with a significant density\nof electronic surface states at the end surfaces, which are either mid-gap\nstates or band-edge states. These states pin the Fermi level, and therefore fix\nthe potential difference across the rod. We provide evidence that this effect\ncan have a determining influence on the polarity of nanorods, and has\nconsequences for the way a rod responds to changes in its surface chemistry,\nthe scaling of its dipole moment with its size, and the dependence of polarity\non its composition.",
        "positive": "Intercorrelated anomalous Hall and spin Hall effect in kagome-lattice\n  Co$_3$Sn$_2$S$_2$-based shandite films: Magnetic Weyl semimetals (mWSMs) are characterized by linearly dispersive\nbands with chiral Weyl node pairs associated with broken time reversal\nsymmetry. One of the hallmarks of mWSMs is the emergence of large intrinsic\nanomalous Hall effect. On heating the mWSM above its Curie temperature, the\nmagnetism vanishes while exchange-split Weyl point pairs collapse into\ndoubly-degenerated gapped Dirac states. Here, we reveal the attractive\npotential of these Dirac nodes in paramagnetic state for efficient spin current\ngeneration at room temperature via the spin Hall effect. Ni and In are\nintroduced to separately substitute Co and Sn in a prototypal mWSM\nCo$_3$Sn$_2$S$_2$ shandite film and tune the Fermi level. Composition\ndependence of spin Hall conductivity for paramagnetic shandite at room\ntemperature resembles that of anomalous Hall conductivity for ferromagnetic\nshandite at low temperature; exhibiting peak-like dependence centering around\nthe Ni-substituted Co$_2$Ni$_1$Sn$_2$S$_2$ and undoped Co$_3$Sn$_2$S$_2$\ncomposition, respectively. The peak shift is consistent with the redistribution\nof electrons' filling upon crossing the ferromagnetic-paramagnetic transition,\nsuggesting intercorrelation between the two Hall effects. Our findings\nhighlight a novel strategy for the quest of spin Hall materials, guided by the\nabundant experimental anomalous Hall effect data of ferromagnets in the\nliterature."
    },
    {
        "anchor": "Raiders of the lost SAR: Radiofrequency cycles of magnetic nanoflowers\n  inside a tumor: Radiofrequency magnetic cycles of \\textit{ex vivo} melanoma tumor tissue\nloaded with Fe$_3$O$_4$ nanoflowers (NF) were measured for several field\nconditions and compared with the cycles of a ferrogel (FG) obtained\nincorporating identical NF in agarose gel. Results were studied in order to\nunderstand a reported specific power dissipation (SAR) reduction of the NF in\nthe actual application medium (tumor) in comparison with a typical\ncharacterization model as the FG. The linearity of the response, together with\ncoercive field and SAR values were analyzed.\\\\ Additionally, a novel method for\nthe determination of the NF mean relaxation time is presented. Results show a\nsystematic difference in magnetic response between the NF incorporated in the\ntumor and those in the FG for all field settings (\\{98, 170, 260\\} kHz and\n\\{17.4, 54.0\\} kA/m) with SAR reductions above 50\\%.",
        "positive": "Spin orbit interaction induced spin-separation in platinum\n  nanostructures: Hirsch (1999) proposed a mechanism and geometry for the observation of the\nspin-Hall effect. In this work, we present a novel realization of the Hirsch\ngeometry in a platinum (Pt) nanostructure, which is an increasingly important\nmaterial for spintronics applications. Measurements were made in a non-local\ngeometry to avoid spurious effects. The measurements show the large spin Hall\nconductivity of Pt. The results are compared with gold (Au) and aluminum (Al).\nPossible theoretical explanations of our observations are briefly mentioned."
    },
    {
        "anchor": "Current-induced mechanical torque in chiral molecular rotors: A great endeavor has been undertaken to engineer molecular rotors operated by\nan electrical current. A frequently met operation principle is the transfer of\nangular momentum taken from the incident flux. In this paper we present an\nalternative driving agent that works also in situations where angular momentum\nof the incoming flux is conserved. This situation arises typically with\nmolecular rotors that exhibit an easy axis of rotation. For quantitative\nanalysis we investigate here a classical model, where molecule and wires are\nrepresented by a rigid curved path. We demonstrate that in the presence of\nchirality the rotor generically undergoes a directed motion, provided that the\nincident current exceeds a threshold value. Above threshold, the corresponding\nrotation frequency (per incoming particle current) for helical geometries turns\nout to be $2\\pi m/M_1$, where $m/M_1$ is the ratio of the mass of an incident\ncharge carrier and the mass of the helix per winding number.",
        "positive": "Renormalization group analysis of graphene with a supercritical Coulomb\n  impurity: We develop a field-theoretic approach to massless Dirac fermions in a\nsupercritical Coulomb potential. By introducing an Aharonov--Bohm solenoid at\nthe potential center, the critical Coulomb charge can be made arbitrarily small\nfor one partial-wave sector, where a perturbative renormalization group\nanalysis becomes possible. We show that a scattering amplitude for reflection\nof particle at the potential center exhibits the renormalization group limit\ncycle, i.e., log-periodic revolutions as a function of the scattering energy,\nrevealing the emergence of discrete scale invariance. This outcome is further\nincorporated in computing the induced charge and current densities, which turn\nout to have power-law tails with coefficients log-periodic with respect to the\ndistance from the potential center. Our findings are consistent with the\nprevious prediction obtained by directly solving the Dirac equation and can in\nprinciple be realized by graphene experiments with charged impurities."
    },
    {
        "anchor": "Transport in Conductors and Rectifiers: Mean-Field Redfield Equations\n  and Non-Equilibrium Green's Functions: We derive a closed equation of motion for the one particle density matrix of\na quantum system coupled to multiple baths using the Redfield master equation\ncombined with a mean-field approximation. The steady-state solution may be\nfound analytically with perturbation theory. Application of the method to a\none-dimensional non-interacting quantum wire yields an expression for the\ncurrent that reproduces the celebrated Landauer's formula. Nonlinear\nrectification is found for the case of a mesoscopic three-dimensional\nsemiconductor p-n junction. The results are in good agreement with numerical\nsimulations obtained using non-equilibrium Green's functions, supporting the\nvalidity of the Redfield equations for the description of transport.",
        "positive": "Chiral states in bilayer graphene: magnetic field dependence and gap\n  opening: At the interface of electrostatic potential kink profiles one dimensional\nchiral states are found in bilayer graphene (BLG). Such structures can be\ncreated by applying an asymmetric potential to the upper and the lower layer of\nBLG. We found that: i) due to the strong confinement by the single kink profile\nthe uni-directional states are only weakly affected by a magnetic field, ii)\nincreasing the smoothness of the kink potential results in additional bound\nstates which are topologically different from those chiral states, and iii) in\nthe presence of a kink-antikink potential the overlap between the oppositely\nmoving chiral states results in the appearance of crossing and anti-crossing\npoints in the energy spectrum. This leads to the opening of tunable minigaps in\nthe spectrum of the uni-directional topological states."
    },
    {
        "anchor": "Fermions out of Dipolar Bosons in the lowest Landau level: In the limit of very fast rotation atomic Bose-Einstein condensates may\nreside entirely in the lowest two-dimensional Landau level (LLL). For small\nenough filling factor of the LLL, one may have formation of fractional quantum\nHall states. We investigate the case of bosons with dipolar interactions as may\nbe realized with Chromium-52 atoms. We show that at filling factor equal to\nunity the ground state is a Moore-Read (a.k.a Pfaffian) paired state as is the\ncase of bosons with purely s-wave scattering interactions. This Pfaffian state\nis destabilized when the interaction in the s-wave channel is small enough and\nthe ground state is a stripe phase with unidimensional density modulation. For\nfilling factor 1/3, we show that there is formation of a Fermi sea of\n``composite fermions''. These composites are made of one boson bound with three\nvortices. This phase has a wide range of stability and the effective mass of\nthe fermions depends essentially only of the scattering amplitude in momentum\nchannels larger or equal to 2. The formation of such a Fermi sea opens up a new\npossible route to detection of the quantum Hall correlations.",
        "positive": "Single-electron transport driven by surface acoustic waves: moving\n  quantum dots versus short barriers: We have investigated the response of the acoustoelectric current driven by a\nsurface-acoustic wave through a quantum point contact in the closed-channel\nregime. Under proper conditions, the current develops plateaus at integer\nmultiples of ef when the frequency f of the surface-acoustic wave or the gate\nvoltage Vg of the point contact is varied. A pronounced 1.1 MHz beat period of\nthe current indicates that the interference of the surface-acoustic wave with\nreflected waves matters. This is supported by the results obtained after a\nsecond independent beam of surface-acoustic wave was added, traveling in\nopposite direction. We have found that two sub-intervals can be distinguished\nwithin the 1.1 MHz modulation period, where two different sets of plateaus\ndominate the acoustoelectric-current versus gate-voltage characteristics. In\nsome cases, both types of quantized steps appeared simultaneously, though at\ndifferent current values, as if they were superposed on each other. Their\npresence could result from two independent quantization mechanisms for the\nacoustoelectric current. We point out that short potential barriers determining\nthe properties of our nominally long constrictions could lead to an additional\nquantization mechanism, independent from those described in the standard model\nof 'moving quantum dots'."
    },
    {
        "anchor": "Electrical control of the hole spin qubit in Si and Ge nanowire quantum\n  dots: Strong, direct Rashba spin-orbit coupling in Si, Ge, and the Ge/Si core/shell\nnanowire quantum dot (QD) allows for all electrical manipulation of the hole\nspin qubit. Motivated by this fact, we analyze different fabrication-dependent\nproperties of nanowires, such as orientation, cross section, and the presence\nof strain, with the goal being to find the material and geometry that enables\nthe fastest qubit manipulation, whose speed can be identified using the Rabi\nfrequency. We show that QD in nanowires with a circular cross section (cNWs)\nenables much weaker driving of the hole spin qubit than QDs embedded in square\nprofile nanowires (sNWs). Assuming the orientation of the Si nanowire that\nmaximizes the spin-orbit effects, our calculations predict that the Rabi\nfrequencies of the hole spin qubits inside Ge and Si sNW QD have comparable\nstrengths for weak electric fields. The global maximum of the Rabi frequency is\nfound in Si sNW QD for strong electric fields, putting this setup ahead of\nothers in creating the hole spin qubit. Finally, we demonstrate that strain in\nthe Si/Ge core/shell nanowire QD decreases the Rabi frequency. In cNW QD, this\neffect is weak; in sNW QD, it is possible to optimize the impact of strain with\nthe appropriate tuning of the electric field strength.",
        "positive": "Ab initio Self-consistent GW Calculations in Non-Equilibrium Devices:\n  Auger Recombination and Electron-Electron Scattering: We present first-principles quantum transport simulations of single-walled\ncarbon nanotubes based on the NEGF method and including carrier-carrier\ninteractions within the self-consistent GW approximation. Motivated by the\ncharacteristic enhancement of interaction between charge carriers in\none-dimensional systems, we show that the developed framework can predict Auger\nrecombination, hot carrier relaxation, and impact ionization in this type of\nnanostructures. Using the computed scattering rates, we infer the inverse\nelectron-hole pair lifetimes for different Auger processes in several device\nconfigurations."
    },
    {
        "anchor": "Anomalous Aharonov-Bohm Interference in the Presence of Edge\n  Reconstruction: Interferometry is a vital tool for studying fundamental features in the\nquantum Hall effect (QHE). For instance, Aharonov-Bohm (AB) interference in a\nquantum Hall interferometer can probe the wave-particle duality of electrons\nand quasiparticles. Here, we report an unusual AB interference in a quantum\nHall Fabry-P\\'erot interferometer (FPI), whose Coulomb interactions were\nsuppressed with a grounded drain in the interior bulk of the FPI. In a\ndescending filling factor from $\\nu =3$ to $\\nu\\approx5/3$, the magnetic field\nperiodicity, which corresponded to a single 'flux quantum,' agreed accurately\nwith the enclosed area of the FPI. However, in the filling range,\n$\\nu\\approx5/3$ to ${\\nu}=1$, the field periodicity increased markedly, apriori\nsuggesting a drastic shrinkage of the AB area. Moreover, the modulation gate\nvoltage periodicity decreased abruptly at this range. We attribute these\nunexpected observations to a ubiquitous edge reconstruction, leading to\ndynamical area changing with the field and a modified modulation gate-edge\ncapacitance. These results are reproducible and support future interference\nexperiments with a QHE-FPI.",
        "positive": "Spin-flip scattering in time-dependent transport through a quantum dot:\n  Enhanced spin-current and inverse tunneling magnetoresistance: We study the effects of spin-flip scatterings on the time-dependent transport\nproperties through a magnetic quantum dot attached to normal and ferromagnetic\nleads. The transient spin-dynamics as well as the steady-state tunneling\nmagnetoresistance (TMR) of the system are investigated. The absence of a\ndefinite spin quantization axis requires the time-propagation of two-component\nspinors. We present numerical results in which the electrodes are treated both\nas one-dimensional tight-binding wires and in the wide-band limit\napproximation. In the latter case we derive a transparent analytic formula for\nthe spin-resolved current, and transient oscillations damped over different\ntime-scales are identified. We also find a novel regime for the TMR inversion.\nFor any given strength of the spin-flip coupling the TMR becomes negative\nprovided the ferromagnetic polarization is larger than some critical value.\nFinally we show how the full knowledge of the transient response allows for\nenhancing the spin-current by properly tuning the period of a pulsed bias."
    },
    {
        "anchor": "Mesoscopic Transport of Quantum Anomalous Hall Effect in Sub-Micron Size\n  Regime: The quantum anomalous Hall (QAH) effect has been demonstrated in\ntwo-dimensional topological insulator systems incorporated with ferromagnetism.\nHowever, a comprehensive understanding of mesoscopic transport in sub-micron\nQAH devices has yet been established. Here we fabricated miniaturized QAH\ndevices with channel widths down to 600 nm, where the QAH features are still\npreserved. A back-scattering channel is formed in narrow QAH devices through\npercolative hopping between 2D compressible puddles. Large resistance\nfluctuations are observed in narrow devices near the coercive field, which is\nassociated with collective interference between intersecting paths along domain\nwalls when the device geometry is smaller than the phase coherence length\n$L_\\phi$. Through measurement of size-dependent breakdown current, we confirmed\nthat the chiral edge states are confined at the physical boundary with its\nwidth on the order of Fermi wavelength.",
        "positive": "Coexistence of electron whispering-gallery modes and atomic collapse\n  states in graphene WSe2 heterostructure quantum dots: The relativistic massless charge carriers with a Fermi velocity of about c300\nin graphene enable us to realize two distinct types of resonances (c, the speed\nof light in vacuum). One is electron whispering-gallery mode in graphene\nquantum dots arising from the Klein tunneling of the massless Dirac fermions.\nThe other is atomic collapse state, which has never been observed in experiment\nwith real atoms due to the difficulty of producing heavy nuclei with charge Z\n170, however, can be realized near a Coulomb impurity in graphene with a charge\nZ 1 because of the small velocity of the Dirac excitations. Here, unexpectedly,\nwe demonstrate that both the electron whispering-gallery modes and atomic\ncollapse states coexist in grapheneWSe2 heterostructure quantum dots due to the\nCoulomb-like potential near their edges. By applying a perpendicular magnetic\nfield, evolution from the atomic collapse states to unusual Landau levels in\nthe collapse regime are explored for the first time."
    },
    {
        "anchor": "Kondo effect in quantum dots coupled to ferromagnetic leads: We study the Kondo effect in a quantum dot which is coupled to ferromagnetic\nleads and analyse its properties as a function of the spin polarization of the\nleads. Based on a scaling approach we predict that for parallel alignment of\nthe magnetizations in the leads the strong-coupling limit of the Kondo effect\nis reached at a finite value of the magnetic field. Using an equation-of-motion\ntechnique we study nonlinear transport through the dot. For parallel alignment\nthe zero-bias anomaly may be split even in the absence of an external magnetic\nfield. For antiparallel spin alignment and symmetric coupling, the peak is\nsplit only in the presence of a magnetic field, but shows a characteristic\nasymmetry in amplitude and position.",
        "positive": "Kondo regime in triangular arrangements of quantum dots: Molecular\n  orbitals, interference and contact effects: Transport properties of an interacting triple quantum dot system coupled to\nthree leads in a triangular geometry has been studied in the Kondo regime.\nApplying mean-field finite-U slave boson and embedded cluster approximations to\nthe calculation of transport properties unveils a set of rich features\nassociated to the high symmetry of this system. Results using both calculation\ntechniques yield excellent overall agreement and provide additional insights\ninto the physical behavior of this interesting geometry. In the case when just\ntwo current leads are connected to the three-dot system, interference effects\nbetween degenerate molecular orbitals are found to strongly affect the overall\nconductance. An S=1 Kondo effect is also shown to appear for the perfect\nequilateral triangle symmetry. The introduction of a third current lead results\nin an `amplitude leakage' phenomenon, akin to that appearing in beam splitters,\nwhich alters the interference effects and the overall conductance through the\nsystem."
    },
    {
        "anchor": "Braiding-based quantum control of a Majorana qubit built from quantum\n  dots: Topology-related ideas might lead to noise-resilient quantum computing. For\nexample, it is expected that the slow spatial exchange (`braiding') of Majorana\nzero modes in superconductors yields quantum gates that are robust against\ndisorder. Here, we report our numerical experiments, which describe the\ndynamics of a Majorana qubit built from quantum dots controlled by\ntime-dependent gate voltages. Our protocol incorporates non-protected control,\nbraiding-based protected control, and readout, of the Majorana qubit. We use\nthe Kitaev chain model for the simulations, and focus on the case when the main\nsource of errors is quasistatic charge noise affecting the hybridization energy\nsplitting of the Majorana modes. We provide quantitative guidelines to suppress\nboth diabatic errors and disorder-induced qubit dephasing, such that a fidelity\nplateau is observed as the hallmark of the topological quantum gate. Our\nsimulations predict realistic features that are expected to be seen in future\nbraiding experiments with Majorana zero modes and other topological qubit\narchitectures.",
        "positive": "Non-local electrical detection of spin-momentum-locked surface currents\n  in the 3D topological insulator BiSbTeSe$_{2}$: The spin-polarized surface states in topological insulators offer unique\ntransport characteristics which make them distinguishable from trivial\nconductors. Due to the topological protection, these states are gapless over\nthe whole surface of the material. Here, we detect the surface states in the\ntopological insulator BiSbTeSe$_{2}$ by electrical means using a non-local\ntransport configuration. We unambiguously probe the spin-momentum locking of\nthe topologically protected surface states by spin-sensitive electrical\nread-out using ferromagnetic Co/Al$_2$O$_3$ electrodes. We show that the\nnon-local measurement allows to probe the surface currents flowing along the\nwhole surface, i.e. from the top along the side to the bottom surface and back\nto the top surface along the opposite side. This is in contrast to local\ntransport configurations where only the surface states of the one face being in\ncontact to the electrodes can be measured. Our results furthermore exclude the\ncontribution of the bulk to the non-local transport at low temperatures.\nIncreasing the temperature, on the other hand, increases the interaction\nbetween bulk and surface states, which shortens the non-local current path\nalong the surface and hence leads to a complete disappearance of the non-local\nsignal at around 20 K. All this demonstrates that the non-local signal at low\ntemperatures is solely due to the topologically protected surface states."
    },
    {
        "anchor": "Electrical control of spin mixing conductance in a\n  Y$_3$Fe$_5$O$_{12}$/Platinum bilayer: We report a tunable spin mixing conductance, up to $\\pm 22\\%$, in a\nY${}_{3}$Fe${}_{5}$O${}_{12}$/Platinum (YIG/Pt) bilayer.This control is\nachieved by applying a gate voltage with an ionic gate technique, which\nexhibits a gate-dependent ferromagnetic resonance line width. Furthermore, we\nobserved a gate-dependent spin pumping and spin Hall angle in the Pt layer,\nwhich is also tunable up to $\\pm$ 13.6\\%. This work experimentally demonstrates\nspin current control through spin pumping and a gate voltage in a YIG/Pt\nbilayer, demonstrating the crucial role of the interfacial charge density for\nthe spin transport properties in magnetic insulator/heavy metal bilayers.",
        "positive": "Electrostatically-induced strain of graphene on GaN nanorods: Few-layer graphene deposited on semiconductor nanorods separated by undoped\nspacers has been studied in perspective for the fabrication of stable\nnanoresonators. We show that an applied bias between the graphene layer and the\nnanorod substrate affects the graphene electrode in two ways: 1) by a change of\nthe carrier concentration in graphene and 2) by inducing strain, as\ndemonstrated by the Raman spectroscopy. The capacitance of the investigated\nstructures scales with the area of graphene in contact with the nanorods. Due\nto the reduced contact surface, the efficiency of graphene gating is one order\nof magnitude lower than for a comparable structure without nanorods. The shift\nof graphene Raman modes observed under bias clearly shows the presence of\nelectrostatically-induced strain and only a weak modification of carrier\nconcentration, both independent of number of graphene layers. A higher impact\nof bias on strain was observed for samples with a larger contact area between\nthe graphene and the nanorods which shows perspective for the construction of\nsensors and nanoresonator devices."
    },
    {
        "anchor": "Non-neutral charged two-dimension system and its quasihole structure: Most of our current knowledge on condensed matters contains a default\nassumption: the matters are neutral charged. On the other hand, the\ntwo-dimension(2D) vortex-Coulomb gas charge analogy is a very successful\ntheoretical tool in explaining superfluid, type-II superconductor and\nfractional quantum Hall effect(FQHE), because the interaction among vortices\nshow similarity with 2D Coulomb potential. Here, by breaking the 'neutral\ncharged' assumption, we suggest the positively charged 2D semiconductor system\ncan possess non-trivial particle-like charge centers(called 'quasihole'), which\nis the charge version of 'vortex'. Using the hypernetted-chain (HNC)\napproximation, the structure of quasihole is elucidated. Numerical calculations\nshow that the quasihole can be projected onto another 2D layer, producing an\nelectric field configuration characterized by 3/2 topological charge.",
        "positive": "Coulomb drag between carbon nanotube and graphene: We report the observation of Coulomb drag between a two-dimensional (2D)\nelectron gas in graphene and a one-dimensional (1D) wire composed of a carbon\nnanotube. We find that drag occurs when the bulk of graphene is conducting, but\nis strongly suppressed in the quantum Hall regime when magnetic field confines\nconducting electrons to the edges of graphene and far from the nanotube.\nOut-of-equilibrium and non-linear drag measurements show intriguing interplay\nbetween 1D and 2D conductors. These hybrid electronic devices of novel geometry\ncould lead to potential applications for Van der Waals electronics"
    },
    {
        "anchor": "Control of spin injection by direct current in lateral spin valves: The spin injection and accumulation in metallic lateral spin valves with\ntransparent interfaces is studied using d.c. injection current. Unlike\na.c.-based techniques, this allows investigating the effects of the direction\nand magnitude of the injected current. We find that the spin accumulation is\nreversed by changing the direction of the injected current, whereas its\nmagnitude does not change. The injection mechanism for both current directions\nis thus perfectly symmetric, leading to the same spin injection efficiency for\nboth spin types. This result is accounted for by a spin-dependent diffusion\nmodel. Joule heating increases considerably the local temperature in the spin\nvalves when high current densities are injected ($\\sim$80--105 K for\n1--2$\\times10^{7}$A cm$^{-2}$), strongly affecting the spin accumulation.",
        "positive": "Phonon-limited carrier mobility and resistivity from carbon nanotubes to\n  graphene: Under which conditions do the electrical transport properties of\none-dimensional (1D) carbon nanotubes (CNTs) and 2D graphene become equivalent?\nWe have performed atomistic calculations of the phonon-limited electrical\nmobility in graphene and in a wide range of CNTs of different types to address\nthis issue. The theoretical study is based on a tight-binding method and a\nforce-constant model from which all possible electron-phonon couplings are\ncomputed. The electrical resistivity of graphene is found in very good\nagreement with experiments performed at high carrier density. A common\nmethodology is applied to study the transition from 1D to 2D by considering\nCNTs with diameter up to 16 nm. It is found that the mobility in CNTs of\nincreasing diameter converges to the same value, the mobility in graphene. This\nconvergence is much faster at high temperature and high carrier density. For\nsmall-diameter CNTs, the mobility strongly depends on chirality, diameter, and\nexistence of a bandgap."
    },
    {
        "anchor": "Nuclear spin effects in singly negatively charged InP quantum dots: Experimental investigation of nuclear spin effects on the electron spin\npolarization in singly negatively charged InP quantum dots is reported.\nPump-probe photoluminescence measurements of electron spin relaxation in the\nmicrosecond timescale are used to estimate the time-period $T_{N}$ of the\nLarmor precession of nuclear spins in the hyperfine field of electrons. We find\n$T_{N}$ to be $\\sim 1$ $\\mu$s at $T \\approx 5$ K, under the vanishing external\nmagnetic field. From the time-integrated measurements of electron spin\npolarization as a function of a longitudinally applied magnetic field at $T\n\\approx 5$ K, we find that the Overhauser field appearing due to the dynamic\nnuclear polarization increases linearly with the excitation power, though its\nmagnitude remains smaller than 10 mT up to the highest excitation power (50 mW)\nused in these experiments. The effective magnetic field of the frozen\nfluctuations of nuclear spins is found to be 15 mT, independent of the\nexcitation power.",
        "positive": "Subgap spectroscopy along hybrid nanowires by nm-thick tunnel barriers: Tunneling spectroscopy is widely used to examine the subgap spectra in\nsemiconductor-superconductor nanostructures when searching for Majorana zero\nmodes (MZMs). Typically, semiconductor sections controlled by local gates at\nthe ends of hybrids serve as tunnel barriers. Besides detecting states only at\nthe hybrid ends, such gate-defined tunnel probes can cause the formation of\nnon-topological subgap states that mimic MZMs. Here, we develop an alternative\ntype of tunnel probes to overcome these limitations. After the growth of an\nInSb-Al hybrid nanowire, a precisely controlled in-situ oxidation of the Al\nshell is performed to yield a nm-thick Al oxide layer. In such thin isolating\nlayer, tunnel probes can be arbitrarily defined at any position along the\nhybrid nanowire by shadow-wall angle-deposition of metallic leads. This allows\nus to make multiple tunnel probes along single nanowire hybrids and to\nsuccessfully identify Andreev bound states (ABSs) of various spatial extension\nresiding along the hybrids."
    },
    {
        "anchor": "Electron states in a double quantum dot with broken axial symmetry: We study theoretically the electron states in a system of two vertically\nstacked quantum dots. We investigate the influence of the geometrical symmetry\nbreaking (caused by the displacement as well as the ellipticity of the dots) on\nthe electron states. Our modeling is based on the 8-band kp method. We show\nthat the absence of axial symmetry of the system leads to a coupling of the s\nstate from one dot with the p and d states from the other. Our findings\nindicate, that this coupling can produce a strong energy splitting at resonance\n(on the order of several meV) in the case of closely spaced quantum dots.\nFurthermore, we show that in the presence of a piezoelectric field, the\ndirection of the displacement plays an important role in the character of the\ncoupling.",
        "positive": "AlAs 2D electrons in an antidot lattice: Electron pinball with\n  elliptical Fermi contours: We report ballistic transport measurements in a two-dimensional electron\nsystem confined to an AlAs quantum well and patterned with square antidot\nlattices of period $a = $0.6, 0.8, 1.0 and 1.5 $\\mu$m. In this system two\nin-plane conduction-band valleys with elliptical Fermi contours are occupied.\nThe low-field magneto-resistance traces exhibit peaks corresponding to the\ncommensurability of the cyclotron orbits and the antidot lattice. From the\ndependence of the position of the peak associated with the smallest\ncommensurate orbit on electron density and $a$, we deduce the ratio of the\nlongitudinal and transverse effective masses $m_l/m_t=5.2\\pm 0.4$, a\nfundamental parameter for the anisotropic conduction bands in AlAs."
    },
    {
        "anchor": "Edge and bulk states in Weyl-orbit quantum Hall effect as studied by\n  Corbino measurements: We investigate edge and bulk states in Weyl-orbit based quantum Hall effect\nby measuring a Corbino-type device fabricated from a topological Dirac\nsemimetal (Cd1-xZnx)3As2 film. Clear quantum Hall plateaus are observed when\nmeasuring one-sided terminals of the Corbino-type device. This indicates that\nedge states of the Weyl-orbit quantum Hall effect form closed trajectories\nconsisting of Fermi arcs and chiral zero modes independently on inner and outer\nsides. On the other hand, the bulk resistance does not diverge at fields where\nthe quantum Hall plateau appears, suggesting that the Weyl orbits in the bulk\nregion are not completely localized when applying electric current through the\nbulk region.",
        "positive": "Coupled structural and magnetic properties of ferric fluoride\n  nanostructures: part II, a Monte-Carlo Heisenberg study: We present a numerical study of the magnetic structure of nanostructured iron\nfluoride, using the Monte-Carlo-Metropolis simulated annealing technique and a\nclassical Heisenberg Hamiltonian with a superexchange angle dependence. The\nparameters are adjusted on experimental results, and the atomic structure and\ntopology taken from a previous atomistic model of grain boundaries in the same\nsystem. We find perfect antiferromagnetic crystalline grains and a disordered\nmagnetic configuration (speromagnetic like) at the grain boundary, in agreement\nwith experimental findings. Both the lowest magnetic energy and the rate of\nmagnetic frustration are found to be dependent on the relative disorientation\nof crystalline grains, i.e. on the cationic topology. By simulating hysteresis\nloops, we find that the magnetization rotation is not spatially uniform. We\nconclude on possible extensions of the model."
    },
    {
        "anchor": "Space- and time-dependent quantum dynamics of spatially indirect\n  excitons in semiconductor heterostructures: We study the unitary propagation of a two-particle one-dimensional\nSchr\\\"odinger equation by means of the Split-Step Fourier method, to study the\ncoherent evolution of a spatially indirect exciton (IX) in semiconductor\nheterostructures. The mutual Coulomb interaction of the electron-hole pair and\nthe electrostatic potentials generated by external gates and acting on the two\nparticles separately are taken into account exactly in the two-particle\ndynamics. As relevant examples, step/downhill and barrier/well potential\nprofiles are considered. The space- and time-dependent evolution during the\nscattering event as well as the asymptotic time behavior are analyzed. For\ntypical parameters of GaAs-based devices the transmission or reflection of the\npair turns out to be a complex two-particle process, due to comparable and\ncompeting Coulomb, electrostatic and kinetic energy scales. Depending on the\nintensity and anisotropy of the scattering potentials, the quantum evolution\nmay result in excitation of the IX internal degrees of freedom, dissociation of\nthe pair, or transmission in small periodic IX wavepackets due to dwelling of\none particle in the barrier region. We discuss the occurrence of each process\nin the full parameter space of the scattering potentials and the relevance of\nour results for current excitronic technologies.",
        "positive": "Majorana fermions manifested as interface-states in semiconductor hybrid\n  structures: Motivated by recent proposals for the generation of Majorana fermions in\nsemiconducting hybrid structures, we examine possible experimental fingerprints\nof such excitations. Whereas previous works mainly have focused on zero-energy\nstates in vortex cores in this context, we demonstrate analytically an\nalternative route to detection of Majorana excitations in semiconducting hybrid\nstructures: interface-bound states that may be probed directly via conductance\nspectroscopy or STM-measurements. We estimate the necessary experimental\nparameters required for observation of our predictions."
    },
    {
        "anchor": "Stochastic polarization formation in exciton-polariton Bose-Einstein\n  condensates: We demonstrate theoretically the spontaneous formation of a stochastic\npolarization in exciton-polariton Bose-Einstein condensates in planar\nmicrocavities under pulsed excitation. Below the threshold pumping intensity\n(dependent on the polariton life-time) the average polarization degree is close\nto zero, whilst above threshold the condensate acquires a polarization\ndescribed by a (pseudospin) vector with random orientation, in general. We\nestablish the link between second order coherence of the polariton condensate\nand the distribution function of its polarization. We examine also the\nmechanisms of polarization dephasing and relaxation.",
        "positive": "Touching points in the energy band structure of bilayer graphene\n  superlattices: Energy band structure of the bilayer graphene superlattices with\nzero-averaged periodic $\\delta$-function potentials are studied within the\nfour-band continuum model. Using the transfer matrix method, studies are mainly\nfocused on examining the touching points between adjacent minibands. For the\nzero-energy touching points the dispersion relation derived shows the\nDirac-like double-cone shape with the group velocity which is periodic in the\npotential strength $P$ with the period of $\\pi$ and becomes anisotropic at\nrelatively large $P$. From the finite-energy touching points we have identified\nthose located at zero wave-number. It was shown that for these finite-energy\ntouching points the dispersion is direction-dependent in the sense that it is\nlinear or parabolic in the direction parallel or perpendicular to the\nsuperlattice direction, respectively. We have also calculated the density of\nstates and the conductivity that demonstrate a manifestation of the touching\npoints of interest."
    },
    {
        "anchor": "Ultrafast racetrack based on compensated Co/Gd-based synthetic\n  ferrimagnet with all-optical switching: Spin-orbitronics and single pulse all-optical switching (AOS) of\nmagnetization are two major successes of the rapidly advancing field of\nnanomagnetism in recent years, with high potential for enabling novel, fast and\nenergy-efficient memory and logic platforms. Fast current-induced domain wall\nmotion (CIDWM) and single shot AOS have been individually demonstrated in\ndifferent ferrimagnetic alloys. However, the stringent requirement for their\ncomposition control makes these alloys challenging materials for wafer-scale\nproduction. Here, we simultaneously demonstrate fast CIDWM and energy efficient\nAOS in a synthetic ferrimagnetic system based on multilayered [Co/Gd/Co/Gd]. We\nfirstly show that AOS is present in its full composition range. We find that\ncurrent-driven domain wall velocities over 2000 m/s at room temperature,\nachieved by compensating the total angular momentum through layer thickness\ntuning. Furthermore, analytical modeling of the CIDWM reveals that Joule\nheating needs to be treated transiently to properly describe the CIDWM for our\nsub-ns current pulses. Our studies establish [Co/Gd]-based synthetic\nferrimagnets to be a unique materials platform for domain wall devices with\naccess to ultrafast single pulse AOS.",
        "positive": "Study of charge-phase diagrams for coupled system of Josephson junctions: Dynamics of stacked intrinsic Josephson junctions (IJJ) in the high-Tc\nsuperconductors is theoretically investigated. We calculate the current-voltage\ncharacteristics (CVC) of IJJ and study the breakpoint region on the outermost\nbranch of the CVC for the stacks with 9 IJJ. A method for investigation of the\nfine structure in CVC of IJJ based on the recording the \"phase-charge\" diagrams\nis suggested. It is demonstrated that this method reflects the main features of\nthe breakpoint region."
    },
    {
        "anchor": "Quantum dots with two electrons: Singlet-triplet transitions: The magnetic character of the ground-state of two electrons on a double\nquantum dot, connected in series to left and right single-channel leads, is\nconsidered. By solving exactly for the spectrum of the two interacting\nelectrons, it is found that the coupling to the continuum of propagating states\non the leads, in conjunction with the electron-electron interactions, may\nresult in a delocalization of the bound state of the two electrons. This, in\nturn, reduces significantly the range of the Coulomb interaction parameters\nover which singlet-triplet transitions can be realized. It is also found that\nthe coupling to the leads favors the singlet ground-state.",
        "positive": "Charge Fluctuations in the Single Electron Box: Quantum fluctuations of the charge in the single electron box are\ninvestigated. Based on a diagrammatic expansion we calculate the average island\ncharge number and the effective charging energy in third order in the tunneling\nconductance. Near the degeneracy point where the energy of two charge states\ncoincides, the perturbative approach fails, and we explicitly resum the leading\nlogarithmic divergencies to all orders. The predictions for zero temperature\nare compared with Monte Carlo data and with recent renormalization group\nresults. While good agreement between the third order result and numerical data\njustifies the perturbative approach in most of the parameter regime relevant\nexperimentally, near the degeneracy point and at zero temperature the\nresummation is shown to be insufficient to describe strong tunneling effects\nquantitatively. We also determine the charge noise spectrum employing a\nprojection operator technique. Former perturbative and semiclassical results\nare extended by the approach."
    },
    {
        "anchor": "The influence of boundary conditions on the form of the optical beam in\n  the array of coupled optical waveguides: We investigate the optical beam behavior in the periodical array of the\ncoupled optical waveguides with the monotonic change of the refractive index in\nthe transverse direction. We consider the dependence of the form of the optical\nbeam on the boundary conditions. It is well known that if the input wave packet\nis wide enough, the optical Bloch oscillations occur, while for the enough\nnarrow input wave packet the breathing mode is observed. We show that if the\ninput wave packet is neither too wide nor too narrow, the optical beam takes a\npeculiar form which can be considered neither as the Bloch oscillations nor as\nthe breathing mode. We qualitatively explain the transformation of this\nintermediate form of the optical beam when the width of the input wave packet\nchanges.",
        "positive": "Revival of antibiskyrmionic magnetic phases in bilayer NiI$_2$: Magnetic skyrmions are topologically protected spin textures with potential\napplications in memory and logic devices. Skyrmions have been commonly observed\nin systems with Dzyaloshinskii-Moriya interaction due to broken inversion\nsymmetry. Yet, recent studies suggest that skyrmions can also be stabilized in\nsystems with inversion symmetry such as Ni-based dihalides due to magnetic\nfrustration. In this article, we employ atomistic simulations to investigate\nchiral magnetic phases in bilayers of NiI$_2$ and NiBr$_2$. We show that the\nantiferromagnetic interlayer coupling introduces an additional magnetic\nfrustration and gives rise to a variety of novel spin textures with different\ntopological charges. Specifically for NiI$_2$, we observe that the skyrmions\nwith the in-plane component of spins wrapping around twice (biskyrmions) have\nan enhanced stability compared to the monolayer case. We also study the\npolarization induced by the non-colinear magnetic order in NiI$_2$ bilayers and\nshow that the polarization of the topologically nontrivial phases is negligible\ncompared to the spiral phases. Thus, we conclude that polarization measurements\ncan be an indirect route for detecting skyrmions in upcoming experiments."
    },
    {
        "anchor": "Electronic Coherence Control in a Charged Quantum Dot: Minimizing decoherence due to coupling of a quantum system to its fluctuating\nenvironment is at the forefront of quantum information science and photonics\nresearch. Nature sets the ultimate limit, however, given by the strength of the\nsystem's coupling to the electromagnetic field. Here, we establish the ability\nto electronically control this coupling and $\\textit{enhance}$ the coherence\ntime of a quantum dot excitonic state. Coherence control is demonstrated on the\npositively charged exciton transition (an electron Coulomb-bound with two\nholes) in quantum dots embedded in a photonic waveguide by manipulating the\nelectron and hole wavefunctions through an applied lateral electric field. With\nincreasing field up to 15 kV cm$^{-1}$, the coherence time increases by a\nfactor of two from $\\sim1.4$ ns to $\\sim2.7$ ns. Numerical calculations reveal\nthat longer coherence arises from the separation of charge carriers by up to\n$\\sim6$ nm, which leads to a $30\\%$ weaker transition dipole moment. The\nability to electrostatically control the coherence time and transition dipole\nmoment opens new avenues for quantum communication and novel coupling schemes\nbetween distant qubits.",
        "positive": "Stability Diagram of a Few-Electron Triple Dot: Quantum dots are considered building blocks for future quantum information\ncircuits. We present here experimental results on a quantum dot circuit\nconsisting of three quantum dots with controlled electron numbers down to one\nper dot and tunable coupling. We experimentally map out for the first time the\nstability diagram of the triatomic system and reveal the existence of quadruple\npoints, a signature of the three dots being in resonance. In their vicinity we\nobserve a surprising effect, a 'cloning' of charge transfer transitions related\nto charge and spin reconfigurations. The experimental results are reproduced by\nequivalent circuit analysis and Hubbard models."
    },
    {
        "anchor": "A one-dimensional continuous model for carbon nanotubes: The continuous two-dimensional (2D) elastic model for single-walled carbon\nnanotubes (SWNTs) provided by Tu and Ou-Yang in [Phys. Rev. B \\textbf{65},\n235411 (2003)] is reduced to a one-dimensional (1D) curvature elastic model\nstrictly. This model is in accordance with the isotropic Kirchhoff elastic rod\ntheory. Neglecting the in-plane strain energy in this model, it is suitable to\ninvestigate the nature features of carbon nanotubes (CNTs) with large\ndeformations and can reduce to the string model in [Phys. Rev. Lett.\n\\textbf{76}, 4055 (1997)] when the deformation is small enough. For straight\nchiral shapes, this general model indicates that the difference of the chiral\nangle between two equilibrium states is about $\\pi/6$, which is consistent with\nthe lattice model. It also reveals that the helical shape has lower energy for\nper atom than the straight shape has in the same condition. By solving the\ncorresponding equilibrium shape equations, the helical tube solution is in good\nagreement with the experimental result, and super helical shapes are obtained\nand we hope they can be found in future experiments.",
        "positive": "Coulomb interaction and electron-hole asymmetry in cyclotron resonance\n  of bilayer graphene in high magnetic field: Inter-Landau-level transitions in the bilayer graphene at high perpendicular\nmagnetic field at the filling-factor v<<1 have been studied. The\nnext-nearest-neighbor transitions, energy difference between dimer and\nnon-dimer sites and layer asymmetry are included. The influence of Coulomb\ninteraction is taken into account. The magnetoplasmon excitations in bilayer\ngraphene at small momenta are considered in the frame of the Hartree-Fock\napproximation. It is shown that asymmetry in cyclotron resonance of clean\nbilayer graphene depends on magnetic field. At lower magnetic fields the energy\nsplitting in the spectrum is due to electron-hole one-particle asymmetry, at\nhigher magnetic fields the energy splitting in the spectrum is due to Coulomb\ninteraction. For the fullsymmetric case with half-filled zero-energy levels the\nenergy splitting proportional to the energy of Coulomb interaction is found\nboth for bilayer and monolayer graphene."
    },
    {
        "anchor": "Toy models of crossed Andreev reflection: We propose toy models of crossed Andreev reflection in multiterminal hybrid\nstructures containing out-of-equilibrium conductors. We apply the description\nto two possible experiments: (i) to a device containing a large quantum dot\ninserted in a crossed Andreev reflection circuit. (ii) To a device containing\nan Aharonov-Bohm loop inserted in a crossed Andreev reflection circuit.",
        "positive": "Dirac dispersion generates large Nernst effect in Weyl semimetals: Weyl semimetals expand research on topologically protected transport by\nadding bulk Berry monopoles with linearly dispersing electronic states and\ntopologically robust, gapless surface Fermi arcs terminating on bulk node\nprojections. Here, we show how the Nernst effect, combining entropy with charge\ntransport, gives a unique signature for the presence of Dirac bands. The Nernst\nthermopower of NbP (maximum of 800 microV K-1 at 9 T, 109 K) exceeds its\nconventional thermopower by a hundredfold and is significantly larger than the\nthermopower of traditional thermoelectric materials. The Nernst effect has a\npronounced maximum near T_M=90 +/- 20 K=mu_0/kB (mu_0 is chemical potential at\nT=0 K). A self-consistent theory without adjustable parameters shows that this\nresults from electrochemical potential pinning to the Weyl point energy at\nT>=TM, driven by charge neutrality and Dirac band symmetry. Temperature and\nfield dependences of the Nernst effect, an even function of the charge\npolarity, result from the intrinsically bipolar nature of the Weyl fermions.\nThrough this study, we offer an understanding of the temperature dependence of\nthe position of the electrochemical potential vis-a-vis the Weyl point, and we\nshow a direct connection between topology and the Nernst effect, a potentially\nrobust experimental tool for investigating topological states and the chiral\nanomaly."
    },
    {
        "anchor": "Edge spin accumulation in semiconductor two-dimensional hole gases: The controlled generation of localized spin densities is a key enabler of\nsemiconductor spintronics In this work, we study spin Hall effect induced edge\nspin accumulation in a two-dimensional hole gas with strong spin orbit\ninteractions. We argue that it is an intrinsic property, in the sense that it\nis independent of the strength of disorder scattering. We show numerically that\nthe spin polarization near the edge induced by this mechanism can be large, and\nthat it becomes larger and more strongly localized as the spin-orbit coupling\nstrength increases, and is independent of the width of the conducting strip\nonce this exceeds the elastic scattering mean-free-path. Our experiments in\ntwo-dimensional hole gas microdevices confirm this remarkable spin Hall effect\nphenomenology. Achieving comparable levels of spin polarization by external\nmagnetic fields would require laboratory equipment whose physical dimensions\nand operating electrical currents are million times larger than those of our\nspin Hall effect devices.",
        "positive": "Density of states and magnetotransport in Weyl semimetals with\n  long-range disorder: We study the density of states and magnetotransport properties of disordered\nWeyl semimetals, focusing on the case of a strong long-range disorder. To\ncalculate the disorder-averaged density of states close to nodal points, we\ntreat exactly the long-range random potential fluctuations produced by charged\nimpurities, while the short-range component of disorder potential is included\nsystematically and controllably with the help of a diagram technique. We find\nthat for energies close to the degeneracy point, long-range potential\nfluctuations lead to a finite density of states. In the context of transport,\nwe discuss that a self-consistent theory of screening in magnetic field may\nconceivably lead to non-monotonic low-field magnetoresistance."
    },
    {
        "anchor": "Decoherence of one-dimensional electron system: Recently, there have been many attempts to implement quantum computation\nexperimentally. For this purpose, quantum coherence should be maintained during\ngate operations. Therefore, the control of decoherence is a very important\nproblem. In present study, we examine the decoherence of one-dimensional\nelectron system, which coupled with acoustic phonon. The time-dependent\nHatree-Fock approximation is applied for electron system, the Schroinger\nequation is applied for phonon.The metal-insulator transition found for\ncoherence time. The results are the election interaction reduces the coherence\ntime. We also exmined the Bang-Bang control, the results shows recovery of\ncoherence.",
        "positive": "Topological transition from nodal to nodeless Zeeman splitting in\n  altermagnets: In an altermagnet, the symmetry that relates configurations with flipped\nmagnetic moments is a rotation. This makes it qualitatively different from a\nferromagnet, where no such symmetry exists, or a collinear antiferromagnet,\nwhere this symmetry is a lattice translation. In this paper, we investigate the\nimpact of the crystalline environment, enabled by the spin-orbit coupling, on\nthe magnetic and electronic properties of an altermagnet. We find that, because\neach component of the magnetization acquires its own angular dependence, the\nZeeman splitting of the bands has symmetry-protected nodal lines residing on\nmirror planes of the crystal. Upon crossing the Fermi surface, these nodal\nlines give rise to pinch points that behave as single or double type-II Weyl\nnodes. We show that an external magnetic field perpendicular to these mirror\nplanes can only move the nodal lines, such that a critical field value is\nnecessary to collapse the nodes and make the Weyl pinch points annihilate. This\nunveils the topological nature of the transition from a nodal to a nodeless\nZeeman splitting of the bands. We also classify the altermagnetic states of\ncommon crystallographic point groups in the presence of spin-orbit coupling,\nrevealing that a broad family of magnetic orthorhombic perovskites can realize\naltermagnetism."
    },
    {
        "anchor": "Electro-optical properties of excitons in Cu$_2$O quantum wells: I\n  discrete states: We present theoretical results of the calculations of optical functions for\nCu$_2$O quantum well (QW) with Rydberg excitons in an external homogeneous\nelectric field of an arbitrary field strength. Two configurations of an\nexternal electric field perpendicular and parallel to the QW planes are\nconsidered in the energetic region for discrete excitonic states and continuum\nstates. With the help of the real density matrix approach, which enables the\nderivation of the analytical expressions for the QW electro-optical functions,\nabsorption spectra are calculated for the case of the excitation energy below\nthe gap energy.",
        "positive": "Directional single-photon emission from deterministic quantum dot\n  waveguide structures: Chiral light-matter interaction can lead to directional emission of two-level\nlight emitters in waveguides. This interesting physics effect has raised\nconsiderable attention in recent years especially in terms of on-chip quantum\nsystems. In this context, our work focuses on tailoring single semiconductor\nquantum dot-waveguide (QD-WG) systems to emit single photons with high\ndirectionality. We use low-temperature in-situ electron-beam lithography\nenabled by cathodoluminescence mapping to select suitable QDs and to integrate\nthem deterministically into linear waveguide structures at specific chiral\npoints determined by numerical calculations. We observe excitonic and\nbiexcitonic emission from the fabricated QD-WG structure in a confocal microPL\nsetup enabling the optical characterization in terms of directional emission of\ncircularly polarized photons emitted by integrated QDs. Our results show a high\ndegree of anisotropy on the level of 54% for directional QD emission and\nantibunching in autocorrelation experiment confirming the fabricated QD-WG\nsystem, which is a prerequisite for using this effect in advanced applications\nin integrated quantum circuits."
    },
    {
        "anchor": "Andreev reflection mediated $\u0394_T$ noise: Quantum noise has been extensively utilized to investigate various aspects of\nquantum transport, such as current-current correlations and wave-particle\nduality. A recent focus in this field is on $\\Delta_T$ quantum noise, which\narises because of a finite temperature difference at vanishing charge current.\nThis paper explores the characterization of $\\Delta_T$ noise auto-correlation\nalongside the shot noise and thermal-noise contributions in a 1D\nmetal/insulator/superconductor junction. We consider a finite temperature\ngradient with zero applied bias for reservoirs at comparable temperatures.\nAndreev reflection enhances the $\\Delta_T$ noise in a\nmetal-insulator-superconductor junction in contrast to a metal-insulator-metal\njunction in the transparent limit. Unlike quantum noise for which shot-noise\ndominates thermal-noise at large bias voltages and finite barrier strength,\n$\\Delta_T$ thermal-noise is always higher than $\\Delta_T$ shot-noise. Thus, a\ngeneral bound that is independent of barrier strength is established. This\ninvestigation sheds light on the distinct behavior of $\\Delta_T$ noise,\nalongside the ratio of shot-noise to thermal-noise contributions, offering\nvaluable insights into the intricate interplay between finite temperature\ngradient, barrier strength, and Andreev reflection.",
        "positive": "Observation of the nonlinear Wood's anomaly on periodic arrays of nickel\n  nanodimers: Linear and nonlinear magneto-photonic properties of periodic arrays of nickel\nnanodimers are governed by the interplay of the (local) optical response of\nindividual nanoparticles and (non-local) diffraction phenomena, with a striking\nexample of Wood's anomaly. Angular and magnetic-field dependencies of the\nsecond harmonic intensity evidence Wood's anomaly when new diffraction orders\nemerge. Near-infrared spectroscopic measurements performed at different optical\nwavelengths and grating constants discriminate between the linear and nonlinear\nexcitation mechanisms of Wood's anomalies. In the nonlinear regime the Wood's\nanomaly is characterized by an order-of-magnitude larger effect in intensity\nredistribution between the diffracted beams, as compared to the linear case.\nThe nonlinear Wood's anomaly manifests itself also in the nonlinear magnetic\ncontrast highlighting the prospects of nonlinear magneto-photonics."
    },
    {
        "anchor": "Geometric and chemical components of the giant piezoresistance in\n  silicon nanowires: A wide variety of apparently contradictory piezoresistance (PZR) behaviors\nhave been reported in p-type silicon nanowires (SiNW), from the usual positive\nbulk effect to anomalous (negative) PZR and giant PZR. The origin of such a\nrange of diverse phenomena is unclear, and consequently so too is the\nimportance of a number of parameters including SiNW type (top down or bottom\nup), stress concentration, electrostatic field effects, or surface chemistry.\nHere we observe all these PZR behaviors in a single set of nominally p-type,\n$\\langle 110 \\rangle$ oriented, top-down SiNWs at uniaxial tensile stresses up\nto 0.5 MPa. Longitudinal $\\pi$-coefficients varying from $-800\\times10^{-11}$\nPa$^{-1}$ to $3000\\times10^{-11}$ Pa$^{-1}$ are measured. Micro-Raman\nspectroscopy on chemically treated nanowires reveals that stress concentration\nis the principal source of giant PZR. The sign and an excess PZR similar in\nmagnitude to the bulk effect are related to the chemical treatment of the SiNW.",
        "positive": "Optical selection rules of graphene nanoribbons: Optical selection rules for one-dimensional graphene nanoribbons are\nanalytically studied and clarified based on the tight-binding model. A\ntheoretical explanation, through analyzing the velocity matrix elements and the\nfeatures of wavefunctions, can account for the selection rules, which depend on\nthe edge structure of nanoribbon, namely armchair or zigzag edges. The\nselection rule of armchair nanoribbons is \\Delta J=0, and the optical\ntransitions occur from the conduction to valence subbands of the same index.\nSuch a selection rule originates in the relationships between two sublattices\nand between conduction and valence subbands. On the other hand, zigzag\nnanoribbons exhibit the selection rule |\\Delta J|=odd, which results from the\nalternatively changing symmetry property as the subband index increases. An\nefficiently theoretical prediction on transition energies is obtained with the\napplication of selection rules. Furthermore, the energies of band edge states\nbecome experimentally attainable via optical measurements."
    },
    {
        "anchor": "Review on Infrared Nanospectroscopy of Natural 2D Phyllosilicates: Phyllosilicates emerge as a promising class of large bandgap lamellar\ninsulators. Their applications have been explored from fabrication of\ngraphene-based devices to 2D heterostructures based on transition metal\ndicalcogenides with enhanced optical and polaritonics properties. In this\nreview, we provide an overview on the use of IR s-SNOM for studying nano-optics\nand local chemistry of a variety of 2D natural phyllosilicates. Finally, we\nbring a brief update on applications that combine natural lamellar minerals\ninto multifunctional nanophotonic devices driven by electrical control.",
        "positive": "Breakdown of the Korringa Law of Nuclear Spin Relaxation in Metallic\n  GaAs: We present nuclear spin relaxation measurements in GaAs epilayers using a new\npump-probe technique in all-electrical, lateral spin-valve devices. The\nmeasured T1 times agree very well with NMR data available for T > 1 K. However,\nthe nuclear spin relaxation rate clearly deviates from the well-established\nKorringa law expected in metallic samples and follows a sub-linear temperature\ndependence 1/T1 ~ T^0.6 for 0.1 K < T < 10 K. Further, we investigate nuclear\nspin inhomogeneities."
    },
    {
        "anchor": "Quasiparticle relaxation of superconducting qubits in the presence of\n  flux: Quasiparticle tunneling across a Josephson junction sets a limit for the\nlifetime of a superconducting qubit state. We develop a general theory of the\ncorresponding decay rate in a qubit controlled by a magnetic flux. The flux\naffects quasiparticles tunneling amplitudes, thus making the decay rate\nflux-dependent. The theory is applicable for an arbitrary quasiparticle\ndistribution. It provides estimates for the rates in practically important\nquantum circuits and also offers a new way of measuring the phase-dependent\nadmittance of a Josephson junction.",
        "positive": "Quantum Hall effect in carbon nanotubes and curved graphene strips: We develop a long wavelength approximation in order to describe the\nlow-energy states of carbon nanotubes in a transverse magnetic field. We show\nthat, in the limit where the square of the magnetic length $l = \\sqrt{\\hbar c\n/e B}$ is much larger than the $C$-$C$ distance times the nanotube radius $R$,\nthe low-energy theory is given by the linear coupling of a two-component Dirac\nspinor to the corresponding vector potential. We investigate in this regime the\nevolution of the band structure of zig-zag nanotubes for values of $R/l > 1$,\nshowing that for radius $R \\approx 20$ nm a clear pattern of Landau levels\nstart to develop for magnetic field strength $B \\gtrsim 10$ T. The levels tend\nto be four-fold degenerate, and we clarify the transition to the typical\ntwo-fold degeneracy of graphene as the nanotube is unrolled to form a curved\nstrip. We show that the dynamics of the Dirac fermions leads to states which\nare localized at the flanks of the nanotube and that carry chiral currents in\nthe longitudinal direction. We discuss the possibility to observe the\nquantization of the Hall conductivity in thick carbon nanotubes, which should\ndisplay steps at even multiples of $2 e^2/h$, with values doubled with respect\nto those in the odd-integer quantization of graphene."
    },
    {
        "anchor": "Conductance fluctuations at the integer quantum Hall plateau transition: We study numerically conductance fluctuations near the integer quantum Hall\neffect plateau transition. The system is presumed to be in a mesoscopic regime,\nwith phase coherence length comparable to the system size. We focus on a\ntwo-terminal conductance G for square samples, considering both periodic and\nopen boundary conditions transverse to the current. At the plateau transition,\nG is broadly distributed, with a distribution function close to uniform on the\ninterval between zero and one in units of e^2/h. Our results are consistent\nwith a recent experiment by Cobden and Kogan on a mesoscopic quantum Hall\neffect sample.",
        "positive": "Photon pair shot noise in electron shot noise: There exists a fascinating dual representation of the electric ac current\nflowing through a normal conductor. On the one hand, it can be understood in\nterms of charge transport. On the other hand, it consists in an electomagnetic\nfield guided by conducting structures embedded in an insulator. The former\npoint of view, in its quantum version, is particularly adapted to describe the\nelectron shot noise in a coherent conductor, like a tunnel junction at\nultra-low temperature. However, when the junction is appropriately biased by a\ndc and an ac voltage, the noise it generates is best analyzed using the latter\nrepresentation and the tools of quantum optics, as the radiation exhibits clear\nsigns of non-classicality. Herein, we report the measurement of the statistics\nof photons emitted by such a tunnel junction. We observe a photon shot noise\ncharacteristic of photon pair emission, as its Fano factor for small signal is\nabove unity. The theory of electron shot noise, dealing exclusively with the\ntunneling of charges through the junction, quantitatively fits the data from\nwhich photon shot noise is extracted. This experiment thus provides a clear\nlink between the dual representations."
    },
    {
        "anchor": "Local transport measurements on epitaxial graphene: Growth of large-scale graphene is still accompanied by imperfections. By\nmeans of a four-tip STM/SEM the local structure of graphene grown on SiC(0001)\nwas correlated with scanning electron microscope images and spatially resolved\ntransport measurements. The systematic variation of probe spacings and\nsubstrate temperature has clearly revealed two-dimensional transport regimes of\nAnderson localization as well as of diffusive transport. The detailed analysis\nof the temperature dependent data demonstrates that the local on-top nano-sized\ncontacts do not induce significant strain to the epitaxial graphene films.",
        "positive": "Charging Ultrasmall Tunnel Junctions in Electromagnetic Environment: We have investigated the quantum admittance of an ultrasmall tunnel junction\nwith arbitrary tunneling strength under an electromagnetic environment. Using\nthe functional integral approach a close analytical expression of the quantum\nadmittance is derived for a general electromagnetic environment. We then\nconsider a specific controllable environment where a resistance is connected in\nseries with the tunneling junction, for which we derived the dc quantum\nconductance from the zero frequency limit of the imaginary part of the quantum\nadmittance. For such electromagnetic environment the dc conductance has been\ninvestigated in recent experiments, and our numerical results agree\nquantitatively very well with the measurements. Our complete numerical results\nfor the entire range of junction conductance and electromagnetic environmental\nconductance confirmed the few existing theoretical conclusions."
    },
    {
        "anchor": "Electron-electron scattering and transport properties of spin-orbit\n  coupled electron gas: We calculate the electrical and thermal conductivity of a two-dimensional\nelectron gas with strong spin--orbit coupling in which the scattering is\ndominated by electron--electron collisions. Despite the apparent absence of\nGalilean invariance in the system, the two-particle scattering does not affect\nthe electrical conductivity above the band-crossing point where both helicity\nbands are filled. Below the band-crossing point where one helicity band is\nempty, switching on the electron--electron scattering leads only to a limited\ndecrease of the electrical conductivity, so that its high-temperature value is\nindependent of the scattering intensity. In contrast to this, thermal\nconductivity is not strongly affected by the spin-orbit coupling and exhibits\nonly a kink as the Fermi level passes through the band-crossing point.",
        "positive": "Direct determination of spin orbit interaction coefficients and\n  realization of the persistent spin helix symmetry: The spin orbit interaction plays a crucial role in diverse fields of\ncondensed matter, including the investigation of Majorana fermions, topological\ninsulators, quantum information and spintronics. In III V zinc blende\nsemiconductor heterostructures, two types of spin orbit interaction, Rashba and\nDresselhaus act on the electron spin as effective magnetic fields with\ndifferent directions. They are characterized by coefficients alpha and beta,\nrespectively. When alpha is equal to beta, the so called persistent spin helix\nsymmetry is realized. In this condition, invariance with respect to spin\nrotations is achieved even in the presence of the spin orbit interaction,\nimplying strongly enhanced spin lifetimes for spatially periodic spin modes.\nExisting methods to evaluate alpha/beta require fitting analyses that often\ninclude ambiguity in the parameters used. Here, we experimentally demonstrate a\nsimple and fitting parameter free technique to determine alpha/beta and to\ndeduce the absolute values of alpha and beta. The method is based on the\ndetection of the effective magnetic field direction and the strength induced by\nthe two spin orbit interactions. Moreover, we observe the persistent spin helix\nsymmetry by gate tuning."
    },
    {
        "anchor": "Effect of pseudospin polarization on wave packet dynamics in graphene\n  antidot lattices (GALs) in the presence of a normal magnetic field: We have investigated the role of pseudospin polarization in electron wave\npacket dynamics in pristine graphene and in a graphene antidot lattice subject\nto an external magnetic field. Employing a Green's function formalism, we show\nthat the electron dynamics can be controlled by tuning pseudospin polarization.\nWe find that in Landau quantized pristine graphene both the propagation of an\nelectron wave packet and Zitterbewegung oscillations strongly depend on\npseudospin polarization. The electron wave packet is found to propagate in the\ndirection of initial pseudospin polarization. We also show that, in this\nsystem, the propagation of an electron can be enhanced in any desired direction\nby carving a one dimensional antidot lattice in that direction. The study\nsuggests that a graphene antidot lattice can serve as a channel for electron\ntransport with the possibility of tunability by means of pseudospin\npolarization, antidot potential and applied normal magnetic field strength.",
        "positive": "Evidence for Disorder Induced Delocalization in Graphite: We present electrical transport measurements in natural graphite and highly\nordered pyrolytic graphite (HOPG), comparing macroscopic samples with\nexfoliated, nanofabricated specimens of nanometer thickness. The latter exhibit\na very large c-axis resistivity $\\rho_c$ -- much larger than expected from\nsimple band theory -- and non-monotonic temperature dependence, similar to\nmacroscopic HOPG, but in stark contrast to macroscopic natural graphite. A\nrecent model of disorder-induced delocalization is consistent with our\ntransport data. Furthermore, Micro-Raman spectroscopy reveals clearly reduced\ndisorder in exfoliated samples and HOPG, as expected within the model --\ntherefore presenting further evidence for a novel paradigm of electronic\ntransport in graphite."
    },
    {
        "anchor": "Ultra-low-energy straintronics using multiferroic composites: This paper reviews the recent developments on building nanoelectronics for\nour future information processing paradigm using multiferroic composites. With\nappropriate choice of materials, when a tiny voltage of few tens of millivolts\nis applied across a multiferroic composite, i.e. a piezoelectric layer\nstain-coupled with a magnetostrictive layer, the piezoelectric layer gets\nstrained and the generated stress in the magnetostrictive layer switches the\nmagnetization direction between its two stable states. We particularly review\nthe switching dynamics of magnetization and calculation of associated metrics\nlike switching delay and energy dissipation. Such voltage-induced magnetization\nswitching mechanism dissipates a minuscule amount of energy of only ~1\nattojoule in sub-nanosecond switching delay at room-temperature. The\nperformance metrics for such non-volatile straintronic devices make them very\nattractive for building not only memory devices but also building logic, so\nthat they can be deemed suitable for computational purposes. Hence,\nmultiferroic straintronics has profound promise of contributing to Beyond\nMoore's law technology, i.e. of being possible replacement of conventional\ncharge-based electronics, which is reaching its performance limit specifically\ndue to excessive energy dissipation.",
        "positive": "Symmetric Operation of the Resonant Exchange Qubit: We operate a resonant exchange qubit in a highly symmetric triple-dot\nconfiguration using IQ-modulated RF pulses. At the resulting three-dimensional\nsweet spot the qubit splitting is an order of magnitude less sensitive to all\nrelevant control voltages, compared to the conventional operating point, but we\nobserve no significant improvement in the quality of Rabi oscillations. For\nweak driving this is consistent with Overhauser field fluctuations modulating\nthe qubit splitting. For strong driving we infer that effective voltage noise\nmodulates the coupling strength between RF drive and the qubit, thereby\nquickening Rabi decay. Application of CPMG dynamical decoupling sequences\nconsisting of up to n = 32 {\\pi} pulses significantly prolongs qubit coherence,\nleading to marginally longer dephasing times in the symmetric configuration.\nThis is consistent with dynamical decoupling from low frequency noise, but\nquantitatively cannot be explained by effective gate voltage noise and\nOverhauser field fluctuations alone. Our results inform recent strategies for\nthe utilization of partial sweet spots in the operation and long-distance\ncoupling of triple-dot qubits."
    },
    {
        "anchor": "No-go theorem for a time-reversal invariant topological phase in\n  noninteracting systems coupled to conventional superconductors: We prove that a system of non-interacting electrons proximity coupled to a\nconventional s-wave superconductor cannot realize a time reversal invariant\ntopological phase. This is done by showing that for such a system, in either\none or two dimensions, the topological invariant of the corresponding symmetry\nclass (DIII) is always trivial. Our results suggest that the pursuit of\nMajorana bound states in time-reversal invariant systems should be aimed at\ninteracting systems or at proximity to unconventional superconductors.",
        "positive": "Probing the p-Ge_{1-x}Si_x/Ge/p-Ge_{1-x}Si_x quantum well by means of\n  the quantum Hall effect: We have measured the temperature (0.1 < T < 15 K) and magnetic field (0 < B <\n32 T) dependences of longitudinal and Hall resistivities for the\np-Ge_{1-x}Si_x/Ge, x=~0.07, multilayers with different Ge layer widths 10 < d_w\n< 38 nm and hole densities p_s = (1-5)x10^{15} m^{-2}. An extremely high\nsensitivity of the experimental data [the structure of magnetoresistance\ntraces, relative values of the inter-Landau-level (LL) gaps deduced from the\nactivated magnetotransport etc] to the quantum well (QW) characteristics has\nbeen revealed in the cases when the Fermi level reaches the second confinement\nsubband. The background density of states (5-10)x10^{14} m^{-2}meV^{-1} deduced\nfrom the activation behavior of the magnetoresistance is too high to be\nattributed to the LL tails, but may be accounted for within a smooth random\npotential model. The hole gas in the Ge QW has been found to separate into two\nsublayers for d_w > ~35 nm and p_s = ~5x10^{15} m^{-2}. A dramatic indication\nto this separation is the disappearance of the quantum Hall (QH) plateau for\nthe filling factor nu = 1 as calculated for the whole Ge layer. Concomitantly a\npositive magnetoresistance emerges in the weakest fields, from which about a\nfactor of two different mobilities in the sublayers have been deduced. A model\nis suggested to explain the existence of the QH plateaux close to the\nfundamental values in a system of two parallel layers with different\nmobilities. A comparison of the simulated structure of the QH\nmagnetoresistivity with the experimental one indicates that the hole densities\nin the sublayers are not much different. Thus, the different mobilities are due\nto different quality of the normal and inverted interfaces of the Ge QW."
    },
    {
        "anchor": "Kohn Anomaly in Raman Spectroscopy of Single Wall Carbon Nanotubes: Phonon softening phenomena of the $\\Gamma$ point optical modes including the\nlongitudinal optical mode, transverse optical mode and radial breathing mode in\n\"metallic\" single wall carbon nanotubes are reviewed from a theoretical point\nof view. The effect of the curvature-induced mini-energy gap on the phonon\nsoftening which depends on the Fermi energy and chirality of the nanotube is\nthe main subject of this article. We adopt an effective-mass model with a\ndeformation-induced gauge field which provides us with a unified way to discuss\nthe curvature effect and the electron-phonon interaction.",
        "positive": "Is there Ballistic Conductance Quantization in Real Life Metals\n  Nanocontacts?: Theory and a vast set of experimental work in metals, since a century, appear\nto show that the mean free path of conduction electrons in a real metal is\nabout the min (bulk mean free path, smallest transversal size of the metal), a\nresult that was already proposed by J. J. Thomson in 1901. This establishes, as\ndiscussed in this work, serious difficulties to justify conductance\nquantization and ballistic transport in atomic/nanocontacts or\nnanoconstrictions of real life metals. The ohmic resistance of the leads proves\nto be as important as the ballistic one of the constriction."
    },
    {
        "anchor": "Genetic Design of Enhanced Valley Splitting towards a Spin Qubit in\n  Silicon: Electronic spins in Silicon (Si) are rising contenders for qubits -- the\nlogical unit of quantum computation-- owing to its outstanding spin coherence\nproperties and compatibility to standard electronics. A remarkable limitation\nfor spin quantum computing in Si hosts is the orbital degeneracy of this\nmaterial's conduction band, preventing the spin-1/2 states from being an\nisolated two-level system. So far available samples of Si quantum wells cladded\nby Ge-Si alloy barriers provide relatively small valley splitting (VS), with\nthe order of 1 meV or less, degrading the fidelity of qubits encoded in spin\n\"up\" and \"down\" states in Si. Here, based on an atomically resolved\npseudopotential theory, we demonstrate that ordered Ge-Si layered barriers\nconfining a Si slab can be harnessed to enhance the VS in the active Si region\nby up to one order of magnitude compared to the random alloy barriers adopted\nso far. A biologically inspired genetic-algorithm search is employed to\nidentify magic Ge/Si layer sequences of the superlattice barriers that isolate\nthe electron ground state in a single valley composition with VS as large as ~9\nmeV. The enhanced VS is preserved with the reasonable inter-layer mixing\nbetween different species, and is interestingly \"protected\" even if some larger\nmixing occurs. Implementation of the optimized layer sequences of barriers,\nwithin reach of modern superlattice growth techniques, overcomes in a practical\nsystematic way the main current limitations related to the orbital degeneracy,\nthus providing a roadmap for reliable spin-only quantum computing in Si.",
        "positive": "Dirac fermion quantization on graphene edges: Isospin-orbit coupling,\n  zero modes and spontaneous valley polarization: The paper addresses boundary electronic properties of graphene with a complex\nedge structure of the armchair/zigzag/armchair type. It is shown that the\nfinite zigzag region supports edge bound states with discrete equidistant\nspectrum obtained from the Green's function of the continuum Dirac equation.\nThe energy levels exhibit the coupling between the valley degree of freedom and\nthe orbital quantum number, analogous to a spin-orbit interaction. The\ncharacteristic feature of the spectrum is the presence of a zero mode, the\nbound state of vanishing energy. It resides only in one of the graphene\nvalleys, breaking spontaneously Kramers' symmetry of the edge states. This\nimplies the spontaneous valley polarization characterized by the valley isospin\n$\\pm 1/2$. The polarization is manifested by a zero-magnetic field anomaly in\nthe local tunneling density of states, and is directly related to the local\nelectric Hall conductivity."
    },
    {
        "anchor": "Flexible graphene/boron nitride nanosheets paper for thermal management\n  of high power electronics: Graphene nanosheets (GNS) paper is widely regarded as a promising candidate\nfor heat dissipation due to its outstanding thermal conductivity. However, the\naccompanied high electrical conductivity makes it unfavorable for thermal\nmanagement of high power electronics since it runs a high risk of short\ncircuits. To eliminate the risk from the high electrical conductivity and\nsimultaneously maintain the excellent thermal performance, we introduce boron\nnitride nanosheets (BNNS) that possess high thermal conductivity but electrical\ninsulation into the GNS paper. The hybrid paper has a much lower electrical\nconductivity but similar thermal performance compared to the pristine GNS\npaper. Besides, the flexible hybrid paper exhibits better thermal stability\nthan pure GNS paper. Our results show that the ability of BNNS to change the\nelectrical conductivity of paper without affecting its thermal conductivity is\npotential for the application of heat management materials with tailored\nelectrical properties.",
        "positive": "Efficient and Accurate Linear Algebraic Methods for Large-scale\n  Electronic Structure Calculations with Non-orthogonal Atomic Orbitals: The need for large-scale electronic structure calculations arises recently in\nthe field of material physics and efficient and accurate algebraic methods for\nlarge simultaneous linear equations become greatly important. We investigate\nthe generalized shifted conjugate orthogonal conjugate gradient method, the\ngeneralized Lanczos method and the generalized Arnoldi method. They are the\nsolver methods of large simultaneous linear equations of one-electron\nSchr\\\"odinger equation and maps the whole Hilbert space to a small subspace\ncalled the Krylov subspace. These methods are applied to systems of fcc Au with\nthe NRL tight-binding Hamiltonian (Phys. Rev. B {\\bf 63}, 195101 (2001)). We\ncompare results by these methods and the exact calculation and show them\nequally accurate. The system size dependence of the CPU time is also discussed.\nThe generalized Lanczos method and the generalized Arnoldi method are the most\nsuitable for the large-scale molecular dynamics simulations from the view point\nof CPU time and memory size."
    },
    {
        "anchor": "Moir\u00e9 exciton dynamics and moir\u00e9 exciton-phonon interaction in a\n  WSe$_2$/MoSe$_2$ heterobilayer: Moir\\'e patterns with angular mismatch in van der Waals heterostructures\ncomposed of atomically thin semiconducting materials are a fascinating platform\nto engineer the optically generated excitonic properties towards novel quantum\nphenomena. The moir\\'e pattern as a periodic trap potential can give rise to\nspatially ordered zero-dimensional (0D) exciton ensembles, which offers the\npossibility for dense coherent quantum emitters and quantum simulation of\nmany-body physics. The intriguing moir\\'e exciton properties are affected by\ntheir dynamics and exciton-phonon interaction. However, the moir\\'e exciton\ndynamics and the interaction between the moir\\'e exciton and phonon are still\nelusive. Here, we report the moir\\'e exciton and phonon interaction in a\ntwisted WSe$_2$/MoSe$_2$ heterobilayer based on near-resonant photoluminescence\nexcitation spectroscopy. We observed the selective excitation of the ground\nstate of the moir\\'e exciton at phonon resonance. The otherwise negligible\nsmall absorption below the continuum state is a hallmark of the density of\nstates of a 0D-like system. In addition, the excitation power dependence of the\nPL spectra reveals the dynamics of moir\\'e exciton ensembles between different\npotential minima with discrete energy levels via the resonant phonon scattering\nprocess. The results presented here of the moir\\'e exciton dynamics under\nsuppressed phonon interaction could pave a new way for the exploration of novel\nquantum phenomena of the moir\\'e exciton towards potential applications in\nquantum optics.",
        "positive": "Can Ballistic Electrons Probe the Electronic Spectra of Individual\n  Buried Molecules?: A theoretical study is presented of the ballistic electron emission spectra\n(BEES) of individual insulating and conducting organic molecules chemisorbed on\na silicon substrate and buried under a thin gold film. It is predicted that\nballistic electrons injected into the gold film from a scanning tunneling\nmicroscope tip should be transmitted so weakly to the silicon substrate by\nalkane molecules of moderate length (decane, hexane) and their thiolates that\nindividual buried molecules of this type will be difficult to detect in BEES\nexperiments. However, resonant transmission by molecules containing unsaturated\nC-C bonds or aromatic rings is predicted to be strong enough for BEES spectra\nof individual buried molecules of these types types to be measured. Calculated\nBEES spectra of molecules of both types are presented and the effects of some\nsimple interstitial and substitutional gold defects that may occur in molecular\nfilms are also briefly discussed."
    },
    {
        "anchor": "The in-plane anisotropy of the hole $g$ factor in CdTe/(Cd,Mg)Te quantum\n  wells studied by spin-dependent photon echoes: We use the two-pulse spin-dependent photon echo technique to study the\nin-plane hole spin anisotropy in a 20~nm-thick CdTe/Cd$_{0.76}$Mg$_{0.24}$Te\nsingle quantum well by exciting the donor-bound exciton resonance. We take\nadvantage of the photon echo sensitivity to the relative phase of the electron\nand hole spin precession and study various interactions contributing to the\nhole in-plane spin properties. The main contribution is found to arise from the\ncrystal cubic symmetry described by the Luttinger parameter $q=0.095$, which is\nsubstantially larger than the one theoretically expected for CdTe or found in\nother quantum well structures. Another contribution is induced by the strain\nwithin the quantum well. These two contributions manifest as different\nharmonics of the spin precession frequencies in the photon echo experiment,\nwhen strength and orientation of the Voigt magnetic field are varied. The\nmagnitude of the effective in-plane hole $g$ factor is found to vary in the\nrange $|\\tilde{g_h}|$=0.125--0.160 in the well plane.",
        "positive": "Tailoring multilayer quantum wells for spin devices: The electron spin dynamics in multilayer GaAs/AlGaAs quantum wells,\ncontaining high-mobility dense two-dimensional electron gases, have been\nstudied using time-resolved Kerr rotation and resonant spin amplification\ntechniques. The electron spin dynamics was regulated through the wave function\nengineering and quantum confinement in multilayer quantum wells. We observed\nthe spin coherence with a remarkably long dephasing time T2* > 13 ns for the\nstructure doped beyond metal-insulator transition. Dyakonov-Perel spin\nrelaxation mechanism, as well as the inhomogeneity of electron g-factor, was\nsuggested as the major limiting factors for the spin coherence time. In the\nmetallic regime, we found that the electron-electron collisions become dominant\nover microscopic scattering on the electron spin relaxation with the\nDyakonov-Perel mechanism. Furthermore, the data analysis indicated that in our\nstructure, due to the spin relaxation anisotropy, Dyakonov-Perel spin\nrelaxation mechanism is efficient for the spins oriented in-plane and\nsuppressed along the quantum well growth direction resulting in the enhancement\nof T2*. Our findings, namely, long-lived spin coherence persisting up to about\nroom temperature, spin polarization decay time with and without a magnetic\nfield, the spin-orbit field, single electron relaxation time, transport\nscattering time, and the electron-electron Coulomb scattering time highlight\nthe attractiveness of n-doped multilayer systems for spin devices."
    },
    {
        "anchor": "Restoration of non-Hermitian bulk-boundary correspondence by\n  counterbalancing skin effect: The non-Hermitian skin effect (NHSE) undermines the conventional\nbulk-boundary correspondence (BBC) since it results in a distinct bulk spectrum\nin open-boundary systems compared to the periodic counterpart. Using the\nnon-Hermitian (NH) Su-Schrieffer-Heeger (SSH) model as an example, we propose\nan intuitive approach, termed ``doubling and swapping\" method, to restore the\nBBC. Explicitly, we construct a modified system by swapping the asymmetric\nintracell hoppings in every second primitive unit cell, such that it has\ndouble-sized unit cells compared to the NH SSH model and is free of NHSE.\nImportantly, the modified system and the NH SSH chain exhibit identical spectra\nunder open boundary conditions (OBC). As a result, the modified system can\nserve as the valid bulk for defining topological invariants that correctly\npredicts edge states and topological phase transitions. The basic principle is\napplicable to many other systems such as the non-Hermitian Creutz ladder model.\nFurthermore, we extend the study to disordered systems in which the asymmetric\nhoppings are randomly swapped. We show that two types of winding numbers can be\ndefined to account for the NHSE and topological edge states, respectively.",
        "positive": "Effective tuning of unusual Aharonov-Bohm oscillations in a single\n  quantum ring: The simultaneous effect of intense THz laser and in-plane electric fields on\nAharonov-Bohm effect in single isotropic quantum rings is investigated using\nthe non-perturbative Floquet theory in high-frequency limit. It is shown that\nin isotropic quantum rings the intense THz laser and in-plane electric field\ncreate unusual Aharonov-Bohm oscillations. For fixed values of intense THz\nlaser field parameter, the amplitudes of Aharonov-Bohm oscillations can be\neffectively tuned by changing the electric field direction. Furthermore, for\nfixed values of electric field strength and laser field parameter the intraband\noptical properties can be effectively tuned by changing the electric field\ndirection. Thus, it can be argued that a circular QR in the intense THz laser\nfield is equivalent to the anisotropic quantum ring, and the electric field\ndirection effectively tunes the unusual Aharonov-Bohm oscillations and\nintraband optical properties of the ring."
    },
    {
        "anchor": "Absence of supercurrent sign reversal in a topological junction with a\n  quantum dot: Experimental techniques to verify Majoranas are of current interest. A\nprominent test is the effect of Majoranas on the Josephson current between two\nwires linked via a normal junction. Here, we study the case of a quantum dot\nconnecting the two superconductors and the sign of the supercurrent in the\ntrivial and topological regimes under grand-canonical equilibrium conditions,\nexplicitly allowing for parity changes due to, e.g., quasi-particle poisoning.\nWe find that the well-known supercurrent reversal for odd occupancy of the\nquantum dot (pi-junction) in the trivial case does not occur in the presence of\nMajoranas in the wires. However, we also find this to be a mere consequence of\nMajoranas being zero energy states. Therefore, the lack of supercurrent sign\nreversal can also be caused by trivial bound states, and is thus not a\ndiscriminating signature of Majoranas.",
        "positive": "Hydrodynamic Phonon Transport: Past, Present, and Prospect: The hydrodynamic phonon transport was studied several decades ago for\nverifying the quantum theory of lattice thermal transport. Recent prediction of\nsignificant hydrodynamic phonon transport in graphitic materials shows its\npractical importance for high thermal conductivity materials and brought a\nrenewed attention. As the study on this topic has been inactive to some extent\nfor several decades, we aim at providing a brief overview of the past studies\nas well as very recent studies. The topics we discuss in this chapter include\nthe collective motion of phonons, several approaches to solve the\nPeierls-Boltzmann transport equation for hydrodynamic phonon transport, the\nrole of normal scattering for thermal resistance, and the propagation of second\nsound. Then, we close this chapter with our perspectives for the future studies\nand the practical implication of hydrodynamic phonon transport."
    },
    {
        "anchor": "Local noise in a diffusive conductor: The control and measurement of local non-equilibrium configurations is of\nutmost importance in applications on energy harvesting, thermoelectrics and\nheat management in nano-electronics. This challenging task can be achieved with\nthe help of various local probes, prominent examples including superconducting\nor quantum dot based tunnel junctions, classical and quantum resistors, and\nRaman thermography. Beyond time-averaged properties, valuable information can\nalso be gained from spontaneous fluctuations of current (noise). From these\nperspective, however, a fundamental constraint is set by current conservation,\nwhich makes noise a characteristic of the whole conductor, rather than some\npart of it. Here we demonstrate how to remove this obstacle and pick up a local\nnoise temperature of a current biased diffusive conductor with the help of a\nminiature noise probe. This approach is virtually noninvasive and extends\nprimary local measurements towards strongly non-equilibrium regimes.",
        "positive": "Manipulation of the electroluminescence of organic light-emitting diodes\n  via fringe fields from patterned magnetic domains: We predict very large changes in the room-temperature electroluminescence of\nthermally-activated delayed fluorescence organic light emitting diodes near\npatterned ferromagnetic films. These effects exceed the changes in a uniform\nmagnetic field by as much as a factor of two. We describe optimal ferromagnetic\nfilm patterns for enhancing the electroluminescence. A full theory of the\nspin-mixing processes in exciplex recombination, and how they are affected by\nhyperfine fields, spin-orbit effects, and ferromagnetic fringe field effects is\nintroduced, and is used to describe the effect of magnetic domain structures on\nthe luminescence in various regimes. This provides a method of enhancing light\nemission rates from exciplexes and also a means of efficiently coupling\ninformation encoded in magnetic domains to organic light emitting diode\nemission."
    },
    {
        "anchor": "Lattice model of three-dimensional topological singlet superconductor\n  with time-reversal symmetry: We study topological phases of time-reversal invariant singlet\nsuperconductors in three spatial dimensions. In these particle-hole symmetric\nsystems the topological phases are characterized by an even-numbered winding\nnumber $\\nu$. At a two-dimensional (2D) surface the topological properties of\nthis quantum state manifest themselves through the presence of $\\nu$ flavors of\ngapless Dirac fermion surface states, which are robust against localization\nfrom random impurities. We construct a tight-binding model on the diamond\nlattice that realizes a topologically nontrivial phase, in which the winding\nnumber takes the value $\\nu =\\pm 2$. Disorder corresponds to a (non-localizing)\nrandom SU(2) gauge potential for the surface Dirac fermions, leading to a\npower-law density of states $\\rho(\\epsilon) \\sim \\epsilon^{1/7}$. The bulk\neffective field theory is proposed to be the (3+1) dimensional SU(2) Yang-Mills\ntheory with a theta-term at $\\theta=\\pi$.",
        "positive": "Quantum Electrodynamic Control of Matter: Cavity-Enhanced Ferroelectric\n  Phase Transition: The light-matter interaction can be utilized to qualitatively alter physical\nproperties of materials. Recent theoretical and experimental studies have\nexplored this possibility of controlling matter by light based on driving\nmany-body systems via strong classical electromagnetic radiation, leading to a\ntime-dependent Hamiltonian for electronic or lattice degrees of freedom. To\navoid inevitable heating, pump-probe setups with ultrashort laser pulses have\nso far been used to study transient light-induced modifications in materials.\nHere, we pursue yet another direction of controlling quantum matter by\nmodifying quantum fluctuations of its electromagnetic environment. In contrast\nto earlier proposals on light-enhanced electron-electron interactions, we\nconsider a dipolar quantum many-body system embedded in a cavity composed of\nmetal mirrors, and formulate a theoretical framework to manipulate its\nequilibrium properties on the basis of quantum light-matter interaction. We\nanalyze hybridization of different types of the fundamental excitations,\nincluding dipolar phonons, cavity photons, and plasmons in metal mirrors,\narising from the cavity confinement in the regime of strong light-matter\ninteraction. This hybridization qualitatively alters the nature of the\ncollective excitations and can be used to selectively control energy-level\nstructures in a wide range of platforms. Most notably, in quantum\nparaelectrics, we show that the cavity-induced softening of infrared optical\nphonons enhances the ferroelectric phase in comparison with the bulk materials.\nOur findings suggest an intriguing possibility of inducing a superradiant-type\ntransition via the light-matter coupling without external pumping. We also\ndiscuss possible applications of the cavity-induced modifications in collective\nexcitations to molecular materials and excitonic devices."
    },
    {
        "anchor": "THz-circuits driven by photo-thermoelectric graphene-junctions: For future on-chip communication schemes, it is essential to integrate\nnanoscale materials with an ultrafast optoelectronic functionality into\nhigh-frequency circuits. The atomically thin graphene has been widely\ndemonstrated to be suitable for photovoltaic and optoelectronic devices because\nof its broadband optical absorption and its high electron mobility. Moreover,\nthe ultrafast relaxation of photogenerated charge carriers has been verified in\ngraphene. Here, we show that dual-gated graphene junctions can be functional\nparts of THz-circuits. As the underlying optoelectronic process, we exploit\nultrafast photo-thermoelectric currents. We describe an immediate\nphoto-thermoelectric current of the unbiased device following a femtosecond\nlaser excitation. For a picosecond time-scale after the optical excitation, an\nadditional photo-thermoelectric contribution shows up, which exhibits the\nfingerprint of a spatially inverted temperature profile. The latter can be\nunderstood by the different time-constants and thermal coupling mechanisms of\nthe electron and phonon baths within graphene to the substrate and the metal\ncontacts. The interplay of the processes gives rise to ultrafast\nelectromagnetic transients in high-frequency circuits, and it is equally\nimportant for a fundamental understanding of graphene-based ultrafast\nphotodetectors and switches.",
        "positive": "Circular edge states in photonic crystals with a Dirac node: Edge states are studied for the two-dimensional Dirac equation in a circular\ngeometry. The properties of the two-component electromagnetic field are\ndiscussed in terms of the three-component polarization field, which can form a\nvortex structure near the Dirac node with a vorticity changing with the sign of\nthe Dirac mass. The Berry curvature of the polarization field is related to the\nBerry curvature of the Dirac spinor state. This quantity is sensitive to a\nchange of boundary conditions. In particular, it vanishes for a geometry with a\nsingle boundary but not for a geometry with two boundaries. This effect is\nrobust against the creation of a step-like edge inside the sample."
    },
    {
        "anchor": "Two-dimensional electron honey: highly viscous electron fluid in which\n  transverse magnetosonic waves can propagate: One of the main macroscopic differences between ordinary and highly viscous\nfluids is the lack of transverse sound in the first and possibility of its\nexcitation in the second. In modern high-mobility conductors (Weyl semimetals,\nbest-quality quantum wells, and graphene) electrons can form a viscous fluid at\nlow temperatures. In this work we develop high-frequency hydrodynamics of\ntwo-dimensional highly viscous electron fluids in magnetic field. Such fluids\nare characterized by simultaneous presence of the excitations associated with\nthe elastic stress (transverse sound) as well as with the violation of the\nlocal charge neutrality (plasmons). We demonstrate that both the viscoelastic\nand the plasmonic components of a flow can exhibit the viscous resonance that\nwas recently proposed for charged viscous fluids. This resonance is related to\nrotation of the viscous stress tensor of a charged fluid in magnetic field. We\nargue that the viscous resonance is responsible for the peak and the\npeculiarities observed in photoresistance and photovoltage of the ultra-high\nmobility GaAs quantum wells. We conclude that a highly viscous electron fluid\n(\"electron honey\") is realized in those structures.",
        "positive": "Evolution of Flat Band and Van Hove Singularities with Interlayer\n  Coupling in Twisted Bilayer Graphene: Here we present a theoretical analysis (applicable to all twist angles of\nTBG) of band dispersion and density of states in TBG relating evolution of flat\nband and Van-Hove singularities with evolution of interlayer coupling in TBG. A\nsimple tight binding Hamiltonian with environment dependent interlayer hopping\nand incorporated with internal configuration of carbon atoms inside a supercell\nis used to calculate band dispersion and density of states in TBG. Various\nHamiltonian parameters and functional form of interlayer hopping applicable to\na wide range of twist angles in TBG is estimated by fitting calculated\ndispersion and density of states with available experimentally observed\ndispersion and density of states in Graphene, AB-stacked bilayer graphene and\nsome TBG systems. Computationally obtained band dispersion reveal that flat\nband in TBG occurs very close to Dirac point of graphene and only along linear\ndimension of two-dimensional wave vector space connecting two closest Dirac\npoints of two graphene layers of TBG."
    },
    {
        "anchor": "Wavepacket Dynamics, Quantum Reversibility and Random Matrix Theory: We introduce and analyze the physics of \"driving reversal\" experiments. These\nare prototype wavepacket dynamics scenarios probing quantum irreversibility.\nUnlike the mostly hypothetical \"time reversal\" concept, a \"driving reversal\"\nscenario can be realized in a laboratory experiment, and is relevant to the\ntheory of quantum dissipation. We study both the energy spreading and the\nsurvival probability in such experiments. We also introduce and study the\n\"compensation time\" (time of maximum return) in such a scenario. Extensive\neffort is devoted to figuring out the capability of either Linear Response\nTheory (LRT) or Random Matrix Theory (RMT) in order to describe specific\nfeatures of the time evolution. We explain that RMT modeling leads to a strong\nnon-perturbative response effect that differs from the semiclassical behavior.",
        "positive": "Spin-Selective Transport of Electron in DNA Double Helix: The experiment that the high spin selectivity and the length-dependent spin\npolarization are observed in double-stranded DNA [Science ${\\bf 331}$, 894\n(2011)], is elucidated by considering the combination of the spin-orbit\ncoupling, the environment-induced dephasing, and the helical symmetry. We show\nthat the spin polarization in double-stranded DNA is significant even in the\ncase of weak spin-orbit coupling, while no spin polarization appears in\nsingle-stranded DNA. Furthermore, the underlying physical mechanism and the\nparameters-dependence of the spin polarization are studied."
    },
    {
        "anchor": "Anomalous Goos-H\u00e4nchen shift in the Floquet scattering of Dirac\n  fermions: We study the inelastic scattering of two-dimensional massless Dirac fermions\nby an inhomogeneous time-dependent driving field. As a physical realization we\nconsider a monolayer graphene normally illuminated with a circularly polarized\nlaser of frequency $\\Omega$ in a given region. The interaction Hamiltonian\nintroduced by the laser, being periodic in time, can be treated with the\nFloquet method which naturally leads to a multi-channel scattering problem. We\nanalyze planar and circular geometries of the interface separating the\nirradiated and non-irradiated regions and find that there is an anomalous\nGoos-H\\\"anchen shift in the inelastic channel. The latter is independent of the\namplitude of the driving while its sign is determined by the polarization of\nthe laser field. We related this shift with the appearance of topological edge\nstates between two illuminated regions of opposite chiralities.",
        "positive": "Topological edge states and quantum Hall effect in the Haldane model: We study the topological edge states of the Haldane's graphene model with\nzigzag/armchair lattice edges. The Harper equation for solving the energies of\nthe edge states is derived. The results show that there are two edge states in\nthe bulk energy gap, corresponding to the two zero points of the Bloch function\non the complex-energy Riemann surface. The edge-state energy loops move around\nthe hole of the Riemann surface in appropriate system parameter regimes. The\nquantized Hall conductance can be expressed by the winding numbers of the edge\nstates, which reflects the topological feature of the Haldane model."
    },
    {
        "anchor": "Superconducting Nanowires as Nonlinear Inductive Elements for Qubits: We report microwave transmission measurements of superconducting Fabry-Perot\nresonators (SFPR), having a superconducting nanowire placed at a supercurrent\nantinode. As the plasma oscillation is excited, the supercurrent is forced to\nflow through the nanowire. The microwave transmission of the resonator-nanowire\ndevice shows a nonlinear resonance behavior, significantly dependent on the\namplitude of the supercurrent oscillation. We show that such\namplitude-dependent response is due to the nonlinearity of the current-phase\nrelationship (CPR) of the nanowire. The results are explained within a\nnonlinear oscillator model of the Duffing oscillator, in which the nanowire\nacts as a purely inductive element, in the limit of low temperatures and low\namplitudes. The low quality factor sample exhibits a \"crater\" at the resonance\npeak at higher driving power, which is due to dissipation. We observe a\nhysteretic bifurcation behavior of the transmission response to frequency sweep\nin a sample with a higher quality factor. The Duffing model is used to explain\nthe Duffing bistability diagram. We also propose a concept of a nanowire-based\nqubit that relies on the current dependence of the kinetic inductance of a\nsuperconducting nanowire.",
        "positive": "Tuning the coupling of an individual magnetic impurity to a\n  superconductor: quantum phase transition and transport: The exchange scattering at magnetic adsorbates on superconductors gives rise\nto Yu-Shiba-Rusinov (YSR) bound states. Depending on the strength of the\nexchange coupling, the magnetic moment perturbs the Cooper pair condensate only\nweakly, resulting in a free-spin ground state, or binds a quasiparticle in its\nvicinity, leading to a (partially) screened spin state. Here, we use the\nflexibility of Fe-porphin molecules adsorbed on a Pb(111) surface to reversibly\nand continuously tune between these distinct ground states. We find that the\nFeP moment is screened in the pristine adsorption state. Approaching the tip of\na scanning tunneling microscope, we exert a sufficiently strong attractive\nforce to tune the molecule through the quantum phase transition into the\nfree-spin state. We ascertain and characterize the transition by investigating\nthe transport processes as function of tip-molecule distance, exciting the YSR\nstates by single-electron tunneling as well as (multiple) Andreev reflections."
    },
    {
        "anchor": "Magneto-optics of general pseudospin-s two-dimensional Dirac-Weyl\n  fermions: The popularity of graphene--a pseudospin-1/2 two-dimensional Dirac-Weyl\nmaterial--has prompted the search for related materials and the\ncharacterization of their properties. In this work, the magneto-optical\nconductivity is calculated for systems that obey the general pseudospin-s\ntwo-dimensional Dirac-Weyl Hamiltonian, with particular focus on s = {1/2, 1,\n3/2, 2}. This generalizes calculations that have been made for s = 1/2 and\nfollows previous work on the optical response of these systems in zero field.\nIn the presence of a magnetic field, Landau levels condense out of the 2s+1\nenergy bands. As the chemical potential in a system is shifted, patterns arise\nin the appearance and disappearance of certain peaks within the optical\nspectra. These patterns are markedly different for each case considered,\ncreating unique signatures in the magneto-optics. The general structure of each\nspectrum and how they compare is discussed.",
        "positive": "Quantum analysis of shot noise suppression in a series of tunnel\n  barriers: We report the results of an analysis, based on a straightforward\nquantum-mechanical model, of shot noise suppression in a structure containing\ncascaded tunneling barriers. Our results exhibit a behavior that is in sharp\ncontrast with existing semiclassical models for this particular type of\nstructure, which predict a limit of 1/3 for the Fano factor as the number of\nbarriers is increased. The origin of this discrepancy is investigated and\nattributed to the presence of localization on the length scale of the mean free\npath, as a consequence of the strictly 1-dimensional nature of disorder, which\ndoes not create mode mixing, while no localization appears in common\nsemiclassical models. We expect localization to be indeed present in practical\nsituations with prevalent 1-D disorder, and the existing experimental evidence\nappears to be consistent with such a prediction."
    },
    {
        "anchor": "Pulse-pumped double quantum dot with spin-orbit coupling: We consider the full driven quantum dynamics of a qubit realized as spin of\nelectron in a one-dimensional double quantum dot with spin-orbit coupling. The\ndriving perturbation is taken in the form of a single half-period pulse of\nelectric field. Spin-orbit coupling leads to a nontrivial evolution in the spin\nand charge densities making the dynamics in both quantities irregular. As a\nresult, the charge density distribution becomes strongly spin-dependent. The\ntransition from the field-induced tunneling to the strong coupling regime is\nclearly seen in the charge and spin channels. These results can be important\nfor the understanding of the techniques for the spin manipulation in\nnanostructures.",
        "positive": "Vacuum polarization of graphene with a supercritical Coulomb impurity:\n  Low-energy universality and discrete scale invariance: We study massless Dirac fermions in a supercritical Coulomb potential with\nthe emphasis on that its low-energy physics is universal and parametrized by a\nsingle quantity per supercritical angular momentum channel. This low-energy\nparameter with the dimension of length is defined only up to multiplicative\nfactors and thus each supercritical channel exhibits the discrete scale\ninvariance. In particular, we show that the induced vacuum polarization has a\npower-law tail whose coefficient is a sum of log-periodic functions with\nrespect to the distance from the potential center. This coefficient can also be\nexpressed in terms of the energy and width of so-called atomic collapse\nresonances. Our universal predictions on the vacuum polarization and its\nrelationship to atomic collapse resonances shed new light on the longstanding\nfundamental problem of quantum electrodynamics and can in principle be tested\nby graphene experiments with charged impurities."
    },
    {
        "anchor": "Theory of weak localization in graphene with spin-orbit interaction: Theory of weak localization in graphene with Rashba splitting of energy\nspectrum is developed. Anomalous magnetoresistance caused by weak localization\nis calculated with account for inter- and intravalley, spin-orbit and\nspin-valley scattering processes. It is shown that the anomalous\nmagnetoresistance is described by the expression different from the traditional\nHikami-Larkin-Nagaoka formula. The reason is that the effect of Rashba\nsplitting gives rise to the spin-orbit vector potential which is not reduced to\na spin dephasing only. The developed theory can be applied to heterostructures\nof graphene with transition metal dichalcogenides.",
        "positive": "Probing Landau quantisation with the presence of insulator-quantum Hall\n  transition in a GaAs two-dimensional electron system: Magneto-transport measurements are performed on the two-dimensional electron\nsystem (2DES) in an AlGaAs/GaAs heterostructure. By increasing the magnetic\nfield perpendicular to the 2DES, magnetoresistivity oscillations due to Landau\nquantisation can be identified just near the direct insulator-quantum Hall\n(I-QH) transition. However, different mobilities are obtained from the\noscillations and transition point. Our study shows that the direct I-QH\ntransition does not always correspond to the onset of strong localisation."
    },
    {
        "anchor": "Microscopic many-body theory of two-dimensional coherent spectroscopy of\n  exciton-polarons in one-dimensional materials: We have developed a microscopic many-body theory of two-dimensional coherent\nspectroscopy (2DCS) for a model of polarons in one-dimensional (1D) materials.\nOur theory accounts for contributions from all three processes: excited-state\nemission (ESE), ground-state bleaching (GSB), and excited-state absorption\n(ESA). While the ESE and GSB contributions can be accurately described using a\nChevy's ansatz with one particle-hole excitation, the ESA process requires\ninformation about the many-body eigenstates involving two impurities. To\ncalculate these double polaron states, we have extended the Chevy's ansatz with\none particle-hole excitation. The validity of this ansatz was verified by\ncomparing our results with an exact calculation using Bethe's ansatz. Our\nnumerical results reveal that in the weak interaction limit, the ESA\ncontribution cancels out the total ESE and GSB contributions, resulting in less\nsignificant spectral features. However, for strong interactions, the features\nof the ESA contribution and the combined ESE and GSB contributions remain\nobservable in the 2DCS spectra. These features provide valuable information\nabout the interactions between polarons. Additionally, we have investigated the\nmixing time dynamics, which characterize the quantum coherences of the polaron\nresonances. Overall, our theory provides a comprehensive framework for\nunderstanding and interpreting the 2DCS spectra of polarons in 1D materials,\nshedding light on their interactions and coherent dynamics.",
        "positive": "Spin Seebeck Power Conversion: Spin caloritronics is the science and technology to control spin, charge, and\nheat currents in magnetic nanostructures. The spin degree of freedom provides\nnew strategies for thermolelectric power generation that have not yet been\nfully explored. After an elementary introduction into conventional\nthermoelectrics and spintronics, we give a brief review of the physics of spin\ncaloritronics. We discuss spin-dependent thermoelectrics based on the the\ntwo-current model in metallic magnets as well as the spin Seebeck and Peltier\neffects that are based on spin wave excitations in ferromagnets. We derive\nexpressions for the efficiency and figure of merit ZT of several spin\ncaloritronic devices."
    },
    {
        "anchor": "Determination of the paradihlorobenzene and paradibromobenzene solid\n  solutions nanoparticles structure via Raman spectra: We measured the small frequencies Raman spectrum of the paradihlorobenzene\nand paradihlorobenzene solid solution nanoparticles with the size about 100\nnanometers. Values of frequencies of lines decrease. The size of nanoparticles\nwas determined by the electronic microscope. Calculations of nanoparticles\nstructure were done using the method of molecular dynamics and histograms of\nnanoparticles spectra were calculated via the Dyne's method. The result is that\nthe Raman spectrum is the sum of spectra from the central part of the\nnanoparticle and superficial structures with smaller concentration of\nparadihlorobenzene.",
        "positive": "Tunable dichroism and optical absorption of graphene by strain\n  engineering: We theoretically study the transmittance for normal incidence of linearly\npolarized light between two media separated by a strained graphene monolayer.\nWe analytically characterize the degree of dichroism and the transparency of\ngraphene as a function of an arbitrary uniform strain and the incident\npolarization. We discuss how measurements of dichroism and transparency for two\ndifferent polarization directions can be used to determine the magnitude and\ndirection of strain. Ours findings result in very useful tools to tune the\ngraphene absorption by mechanical strain, as well as to design nano-devices to\ndetermine crack propagation in materials."
    },
    {
        "anchor": "Quantum Geometry Induced Third Order Nonlinear Transport Responses: Nonlinear transport phenomena offer an exciting probe into the band geometry\nand symmetry properties of a system. Here, we present the complete theory of\nthird-order nonlinear charge transport using the density matrix-based quantum\nkinetic framework. We predict a unique intrinsic dissipative contribution and\nidentify a novel intrinsic dissipationless Hall response. We demonstrate that\nthese previously unexplored contributions arise in time-reversal\nsymmetry-broken systems from band geometric quantities such as the Berry\ncurvature and the symplectic connection. We prescribe a detailed symmetry\ndictionary to facilitate the discovery of these fundamental transport\ncoefficients. Additionally, we unify our quantum kinetic results with the\nsemiclassical wave-packet formalism to unveil all contributions to third-order\ncharge transport. We illustrate our results in antiferromagnetic monolayer\nSrMnBi$_2$. Our study significantly advances the fundamental understanding of\nthird-order responses.",
        "positive": "Atomic-Scale Visualization and Manipulation of Domain boundaries in 2D\n  Ferroelectric In2Se3: Domain boundaries in ferroelectric materials exhibit rich and diverse\nphysical properties distinct from their parent materials and have been proposed\nfor novel applications in nanoelectronics and quantum information technology.\nDue to their complexity and diversity, the internal atomic and electronic\nstructure of domain boundaries that governs the electronic properties as well\nas the kinetics of domain switching remains far from being elucidated. By using\nscanning tunneling microscopy and spectroscopy (STM/S) combined with density\nfunctional theory (DFT) calculations, we directly visualize the atomic\nstructure of domain boundaries in two-dimensional (2D) ferroelectric beta'\nIn2Se3 down to the monolayer limit and reveal a double-barrier energy potential\nof the 60{\\deg} tail to tail domain boundaries for the first time. We further\ncontrollably manipulate the domain boundaries with atomic precision by STM and\nshow that the movements of domain boundaries can be driven by the electric\nfield from an STM tip and proceed by the collective shifting of atoms at the\ndomain boundaries. The results will deepen our understanding of domain\nboundaries in 2D ferroelectric materials and stimulate innovative applications\nof these materials."
    },
    {
        "anchor": "Terahertz modulated optical sideband generation in graphene: Exploration of optical non-linear response of graphene predominantly relies\non ultra-short time domain measurements. Here we propose an alternate technique\nthat uses frequency modulated continuous wavefront optical fields, thereby\nprobing graphene's steady state non-linear response. We predict frequency\nsideband generation in the reflected field that originates from coherent\nelectron dynamics of the photo-excited carriers. The corresponding threshold in\ninput intensity for optimal sideband generation provides a direct measure of\nthe third order optical non-linearity in graphene. Our formulation yields\nanalytic forms for the generated sideband intensity, is applicable to generic\ntwo-band systems and suggests a range of applications that include switching of\nfrequency sidebands using non-linear phase shifts and generation of frequency\ncombs.",
        "positive": "On-demand generation of higher-order Fock states in quantum-dot--cavity\n  systems: The on-demand preparation of higher-order Fock states is of fundamental\nimportance in quantum information sciences. We propose and compare different\nprotocols to generate higher-order Fock states in solid state\nquantum-dot--cavity systems. The protocols make use of a series of laser pulses\nto excite the quantum dot exciton and off-resonant pulses to control the\ndetuning between dot and cavity. Our theoretical studies include dot and cavity\nloss processes as well as the pure-dephasing type coupling to longitudinal\nacoustic phonons in a numerically complete fashion. By going beyond the\ntwo-level approximation for quantum dots, we study the impact of a finite\nexchange splitting, the impact of a higher energetic exciton state, and an\nexcitation with linearly polarized laser pulses leading to detrimental\noccupations of the biexciton state. We predict that under realistic conditions,\na protocol which keeps the cavity at resonance with the quantum dot until the\ndesired target state is reached is able to deliver fidelities to the Fock state\n$| 5\\rangle$ well above $40\\,\\%$."
    },
    {
        "anchor": "Optical non-linearities and spontaneous translational symmetry breaking\n  in driven-dissipative moir\u00e9 exciton-polaritons: Moir\\'e lattices formed from semiconductor bilayers host tightly localised\nexcitons that can simultaneously couple strongly to light and possess large\nelectric dipole moments. This facilitates the realization of new forms of\npolaritons that are very strongly interacting and that have been predicted to\nlead to strong optical nonlinearities controlled by multi-photon resonances.\nHere, we investigate the role of the non-local component of the exciton-exciton\n(dipolar) interactions on the optical response of these strongly-interacting\nmoir\\'e exciton-polaritons under conditions of strong optical driving. We find\nthat the non-local interactions can strongly influence the steady-state\nproperties leading to multi-stabilities with broken translational symmetry and\npronounced distortions of the multi-photon resonances. We develop a\nself-consistent approach to describe the steady-state solution of moir\\'e\nexcitons coupled to a cavity field, treating the long-range interaction between\nthe excitons and the photon field at the semi-classical level.",
        "positive": "Resonant Regimes in the Fock-Space Coherence of Multilevel Quantum Dots: The coherence between quantum states with different particle numbers --- the\nFock-space coherence --- qualitatively differs from the more common\nHilbert-space coherence between states with equal particle numbers. For a\nquantum dot with multiple channels available for transport, we find the\nconditions for decoupling the dynamics of the Fock-space coherence from both\nthe Hilbert-space coherence as well as the population dynamics. We further find\nspecific energy and coupling regimes where a long-lived resonance in the\nFock-space coherence of the system is realized, even where no resonances are\nfound either in the populations or Hilbert-space coherence. Numerical\ncalculations show this resonance remains robust in the presence of both\nboson-mediated relaxation and transport through the quantum dot."
    },
    {
        "anchor": "Classification of topological insulators and superconductors in the\n  presence of reflection symmetry: We discuss a topological classification of insulators and superconductors in\nthe presence of both (non-spatial) discrete symmetries in the Altland-Zirnbauer\nclassification and spatial reflection symmetry in any spatial dimensions. By\nusing the structure of bulk Dirac Hamiltonians of minimal matrix dimensions and\nexplicit constructions of topological invariants, we provide the complete\nclassification, which still has the same dimensional periodicities with the\noriginal Altland-Zirnbauer classification. The classification of\nreflection-symmetry-protected topological insulators and superconductors\ndepends crucially on the way reflection symmetry operation is realized. When a\nboundary is introduced, which is reflected into itself, these non-trivial\ntopological insulators and superconductors support gapless modes localized at\nthe boundary.",
        "positive": "Optical conductivity of curved graphene: We compute the optical conductivity for an out-of-plane deformation in\ngraphene using an approach based on solutions of the Dirac equation in curved\nspace. Different examples of periodic deformations along one direction\ntranslates into an enhancement of the optical conductivity peaks in the region\nof the far and mid infrared frequencies for periodicities $\\sim100\\,$nm. The\nwidth and position of the peaks can be changed by dialling the parameters of\nthe deformation profiles. The enhancement of the optical conductivity is due to\nintraband transitions and the translational invariance breaking in the\ngeometrically deformed background. Furthemore, we derive an analytical solution\nof the Dirac equation in a curved space for a general deformation along one\nspatial direction. For this class of geometries, it is shown that curvature\ninduces an extra phase in the electron wave function, which can also be\nexplored to produce interference devices of the Aharonov-Bohm type."
    },
    {
        "anchor": "The rise of spin-flip transitions in the anomalous Hall effect of FePt\n  alloy: We carry out first-principles calculations which demonstrate the importance\nof spin-flip transitions for the intrinsic anomalous Hall conductivity of\nordered FePt alloys. We show the such transitions get enhanced by large\nspin-orbit coupling of Pt atoms, becoming negligible when Pt is replaced by\nlighter isoelectronic Pd. We find that spin-flip transitions in FePt originate\nnot only from conventional band anticrossings at the Fermi level, but also from\ntransitions between well-separated pairs of bands with similar dispersions. We\nalso predict a strong anisotropy in the anomalous Hall conductivity of FePt,\nwhich comes from spin-flip transitions entirely, and investigate the influence\nof disorder on it.",
        "positive": "Observation of chiral quantum-Hall edge states in graphene: In this study, we determined the chiral direction of the quantum-Hall (QH)\nedge states in graphene by adopting simple two-terminal conductance\nmeasurements while grounding different edge positions of the sample. The edge\nstate with a smaller filling factor is found to more strongly interact with the\nelectric contacts. This simple method can be conveniently used to investigate\nthe chirality of the QH edge state with zero filling factor in graphene, which\nis important to understand the symmetry breaking sequence in high magnetic\nfields ($\\gtrsim$25 T)."
    },
    {
        "anchor": "Surface acoustic wave attenuation by a two-dimensional electron gas in a\n  strong magnetic field: The propagation of a surface acoustic wave (SAW) on GaAs/AlGaAs\nheterostructures is studied in the case where the two-dimensional electron gas\n(2DEG) is subject to a strong magnetic field and a smooth random potential with\ncorrelation length Lambda and amplitude Delta. The electron wave functions are\ndescribed in a quasiclassical picture using results of percolation theory for\ntwo-dimensional systems. In accordance with the experimental situation, Lambda\nis assumed to be much smaller than the sound wavelength 2*pi/q. This restricts\nthe absorption of surface phonons at a filling factor \\bar{\\nu} approx 1/2 to\nelectrons occupying extended trajectories of fractal structure. Both\npiezoelectric and deformation potential interactions of surface acoustic\nphonons with electrons are considered and the corresponding interaction\nvertices are derived. These vertices are found to differ from those valid for\nthree-dimensional bulk phonon systems with respect to the phonon wave vector\ndependence. We derive the appropriate dielectric function varepsilon(omega,q)\nto describe the effect of screening on the electron-phonon coupling. In the low\ntemperature, high frequency regime T << Delta (omega_q*Lambda\n/v_D)^{alpha/2/nu}, where omega_q is the SAW frequency and v_D is the electron\ndrift velocity, both the attenuation coefficient Gamma and varepsilon(omega,q)\nare independent of temperature. The classical percolation indices give\nalpha/2/nu=3/7. The width of the region where a strong absorption of the SAW\noccurs is found to be given by the scaling law |Delta \\bar{\\nu}| approx\n(omega_q*Lambda/v_D)^{alpha/2/nu}. The dependence of the electron-phonon\ncoupling and the screening due to the 2DEG on the filling factor leads to a\ndouble-peak structure for Gamma(\\bar{\\nu}).",
        "positive": "On Behind the Physics of the Thermoelectricity of Topological Insulators: Topological Insulators are the best thermoelectric materials involving a\nsophisticated physics beyond their solid state and electronic structure. We\nshow that exists a topological contribution to the thermoelectric effect that\narise between topological and thermal quantum field theories applied at very\nlow energies. This formalism provides us with a quantized topological mass\nproportional to the temperature T, being both quantities directly related with\nan electric potential V and getting a Seebeck coefficient where we identify an\nanomalous contribution that we associate to the creation of real electron-hole\nSchwinger's pairs close to the topological bands. Finally, we find a general\nexpression, considering the electronic contribution, for the dimensionless\nfigure of merit of these topological materials, getting a value of 2.73 that is\napplicable to the Bi$_2$Te$_3$, for which it was reported a value of 2.4, using\nonly the most basic topological numbers (0 or 1)."
    },
    {
        "anchor": "In Situ Imaging of the Conducting Filament in a Silicon Oxide Resistive\n  Switch: The nature of the conducting filaments in many resistive switching systems\nhas been elusive. Through in situ transmission electron microscopy, we image\nthe real-time formation and evolution of the filament in a silicon oxide\nresistive switch. The electroforming process is revealed to involve the local\nenrichment of silicon from the silicon oxide matrix. Semi-metallic silicon\nnanocrystals with structural variations from the conventional diamond cubic\nform of silicon are observed, which likely accounts for the conduction in the\nfilament. The growth and shrinkage of the silicon nanocrystals in response to\ndifferent electrical stimuli show energetically viable transition processes in\nthe silicon forms, offering evidence to the switching mechanism. The study here\nalso provides insights into the electrical breakdown process in silicon oxide\nlayers, which are ubiquitous in a host of electronic devices.",
        "positive": "Effect of Anisotropy on the Localization in a Bifractal System: Bifractal is a highly anisotropic structure where planar fractals are stacked\nto form a 3-dimensional lattice. The localization lengths along fractal\nstructure for the Anderson model defined on a bifractal are calculated. The\ncritical disorder and the critical exponent of the localization lengths are\nobtained from the finite size scaling behavior. The numerical results are in a\ngood agreement with previous results which have been obtained from the\nlocalization lengths along the perpendicular direction. This suggests that the\nanisotropy of the embedding lattice structure is irrelevant to the critical\nproperties of the localization."
    },
    {
        "anchor": "Random-matrix theory of Andreev reflection from a topological\n  superconductor: We calculate the probability distribution of the Andreev reflection\neigenvalues R_n at the Fermi level in the circular ensemble of random-matrix\ntheory. Without spin-rotation symmetry, the statistics of the electrical\nconductance G depends on the topological quantum number Q of the\nsuperconductor. We show that this dependence is nonperturbative in the number N\nof scattering channels, by proving that the p-th cumulant of G is independent\nof Q for p<N/d (with d=2 or d=1 in the presence or in the absence of\ntime-reversal symmetry). A large-N effect such as weak localization cannot,\ntherefore, probe the topological quantum number. For small N we calculate the\nfull distribution P(G) of the conductance and find qualitative differences in\nthe topologically trivial and nontrivial phases.",
        "positive": "Imaging the lateral shift of a quantum-point contact using scanning-gate\n  microscopy: We perform scanning-gate microscopy on a quantum-point contact. It is defined\nin a high-mobility two-dimensional electron gas of an AlGaAs/GaAs\nheterostructure, giving rise to a weak disorder potential. The lever arm of the\nscanning tip is significantly smaller than that of the split gates defining the\nconducting channel of the quantum-point contact. We are able to observe that\nthe conducting channel is shifted in real space when asymmetric gate voltages\nare applied. The observed shifts are consistent with transport data and\nnumerical estimations."
    },
    {
        "anchor": "Weak-localization and spin-orbit interaction in side-gate field effect\n  devices at the LaAlO$_3$/SrTiO$_3$ interface: Using field effect devices with side gates, we modulate the 2 dimensional\nelectron gas hosted at the LaAlO$_3$/SrTiO$_3$ interface to study the\ntemperature and doping evolution of the magnetotransport. The analysis of the\ndata reveals different transport regimes depending on the interplay between the\ndifferent (elastic, inelastic, and spin-orbit) scattering times and their\ntemperature dependencies. We find that the spin-orbit interaction strongly\naffects the low temperature transport in the normal state in a very large\nregion of the phase diagram, extending beyond the superconducting dome.",
        "positive": "Transient Response of the Cavity-Magnon-Polariton: The Rabi oscillations of a coupled spin-photon system are experimentally\nstudied using time domain microwave transmission measurements. An external\nmagnetic bias field is applied to control the amplitude and frequency of Rabi\noscillations, which are a measure of the coherent spin-photon energy exchange\nand coupling strength respectively. The amplitude and frequency control is\ndescribed in the time domain as the transient response of a two-level\nspin-photon system. This approach reveals the link between steady state and\ntransient behaviour of the cavity-magnon-polariton, which is necessary to\ninterpret time domain cavity-spintronic experiments. This transient model also\nallows us to understand and quantify the polariton mode composition, which can\nbe controlled by the bias field."
    },
    {
        "anchor": "Phase Sensitive Shot Noise in an Andreev Interferometer: We investigate nonequilibrium noise in a diffusive Andreev interferometer, in\nwhich currents emerging from two Normal metal/Superconductor (N-S) interfaces\ncan interfere. We observe a modulation of the shot noise when the phase\ndifference between the two N-S interfaces is varied by a magnetic flux. This is\nthe signature of phase-sensitive fluctuations in the normal metal. The\neffective charge inferred from the shot noise measurement is close to q_eff=2e\nbut shows phase-dependent deviations from 2e at finite energy, which we\ninterprete as due to pair correlations. Experimental data are in good agreement\nwith theoretical predictions based on an extended Keldysh Green's function\napproach.",
        "positive": "Electrostatically Induced Superconductivity at the Surface of WS$_2$: We investigate transport through ionic liquid gated field effect transistors\n(FETs) based on exfoliated crystals of semiconducting WS$_2$. Upon electron\naccumulation, at surface densities close to -or just larger than- 10$^{14}$\ncm$^{-2}$, transport exhibits metallic behavior, with the surface resistivity\ndecreasing pronouncedly upon cooling. A detailed characterization as a function\nof temperature and magnetic field clearly shows the occurrence of a\ngate-induced superconducting transition below a critical temperature $T_c\n\\approx 4$ K, a finding that represents the first demonstration of\nsuperconductivity in tungsten-based semiconducting transition metal\ndichalcogenides. We investigate the nature of superconductivity and find\nsignificant inhomogeneity, originating from the local detaching of the frozen\nionic liquid from the WS$_2$ surface. Despite the inhomogeneity, we find that\nin all cases where a fully developed zero resistance state is observed,\ndifferent properties of the devices exhibit a behavior characteristic of a\nBerezinskii-Kosterlitz-Thouless transition, as it could be expected in view of\nthe two-dimensional nature of the electrostatically accumulated electron\nsystem."
    },
    {
        "anchor": "Theory of laser-induced demagnetization at high temperatures: Laser-induced demagnetization is theoretically studied by explicitly taking\ninto account interactions among electrons, spins and lattice. Assuming that the\ndemagnetization processes take place during the thermalization of the\nsub-systems, the temperature dynamics is given by the energy transfer between\nthe thermalized interacting baths. These energy transfers are accounted for\nexplicitly through electron-magnons and electron-phonons interaction, which\ngovern the demagnetization time scale. By properly treating the spin system in\na self-consistent random phase approximation, we derive magnetization dynamic\nequations for a broad range of temperature. The dependence of demagnetization\non the temperature and pumping laser intensity is calculated in detail. In\nparticular, we show several salient features for understanding magnetization\ndynamics near the Curie temperature. While the critical slowdown in dynamics\noccurs, we find that an external magnetic field can restore the fast dynamics.\nWe discuss the implication of the fast dynamics in the application of heat\nassisted magnetic recording.",
        "positive": "Transport properties of double-walled carbon nanotube quantum dots: The transport properties of quantum dot (QD) systems based on double-walled\ncarbon nanotube (DWCNT) are investigated. The interplay between microscopic\nstructure and strong Coulomb interaction is treated within a bosonization\nframework. The linear and nonlinear G-V-V_g characteristics of the QD system is\ncalculated by starting from the Liouville equation for the reduced density\nmatrix. Depending on the intershell couplings, an 8-electron periodicity of the\nCoulomb blockade peak spacing in the case of commensurate DWCNT QDs and a\n4-electron periodicity in the incommensurate case are predicted. The\ncontribution of excited states of DWCNTs to the nonlinear transport is\ninvestigated as well."
    },
    {
        "anchor": "Topological zero modes and Dirac points protected by spatial symmetry\n  and chiral symmetry: We explore a new class of topologically stable zero energy modes which are\nprotected by coexisting chiral and spatial symmetries. If a chiral symmetric\nHamiltonian has an additional spatial symmetry such as reflection, inversion\nand rotation, the Hamiltonian can be separated into independent\nchiral-symmetric subsystems by the eigenvalue of the space symmetry operator.\nEach subsystem supports chiral zero energy modes when a topological index\nassigned to the block is nonzero. By applying the argument to Bloch electron\nsystems, we detect band touching at symmetric points in the Brillouin zone. In\nparticular, we show that Dirac nodes appearing in honeycomb lattice (e.g.\ngraphene) and in half-flux square lattice are protected by three-fold and\ntwo-fold rotation symmetry, respectively. We also present several examples of\nDirac semimetal with isolated band-touching points in three-dimensional\n$k$-space, which are protected by combined symmetry of rotation and reflection.\nThe zero mode protection by spatial symmetry is distinct from that by the\nconventional winding number. We demonstrate that symmetry-protected band\ntouching points emerge even though the winding number is zero. Finally, we\nidentify relevant topological charges assigned to the gapless points.",
        "positive": "Peierls-type Instability and Tunable Band Gap in Functionalized Graphene: Functionalizing graphene was recently shown to have a dramatic effect on the\nelectronic properties of this material. Here we investigate spatial ordering of\nadatoms driven by the RKKY-type interactions. In the ordered state, which\narises via a Peierls-instability-type mechanism, the adatoms reside mainly on\none of the two graphene sublattices. Bragg scattering of electron waves induced\nby sublattice symmetry breaking results in a band gap opening, whereby Dirac\nfermions acquire a finite mass. The band gap is found to be immune to the\nadatoms' positional disorder, with only an exponentially small number of\nlocalized states residing in the gap. The gapped state is stabilized in a wide\nrange of electron doping. Our findings show that controlled adsorption of\nadatoms or molecules provides a route to engineering a tunable band gap in\ngraphene."
    },
    {
        "anchor": "Topological gap labeling with the third Chern numbers in\n  three-dimensional quasicrystals: We study the topological gap labeling of general 3D quasicrystals and we find\nthat every gap in the spectrum is characterized by a set of the third Chern\nnumbers. We show that a quasi-periodic structure has multiple Brillouin zones\ndefined by redundant wavevectors, and the number of states below a gap is\nquantized as an integer linear combination of volumes of these Brillouin zones.\nThe associated quantum numbers to characterize energy gaps can be expressed as\nthird Chern numbers by considering a formal relationship between an adiabatic\ncharge pumping under cyclic deformation of the quasi-periodic potential and a\ntopological nonlinear electromagnetic response in 6D insulators.",
        "positive": "Electron-phonon scattering at the intersection of two Landau levels: We predict a double-resonant feature in the magnetic field dependence of the\nphonon-mediated longitudinal conductivity $\\sigma_{xx}$ of a two-subband\nquasi-two-dimensional electron system in a quantizing magnetic field. The two\nsharp peaks in $\\sigma_{xx}$ appear when the energy separation between two\nLandau levels belonging to different size-quantization subbands is favorable\nfor acoustic-phonon transitions. One-phonon and two-phonon mechanisms of\nelectron conductivity are calculated and mutually compared. The phonon-mediated\ninteraction between the intersecting Landau levels is considered and no avoided\ncrossing is found at thermal equilibrium."
    },
    {
        "anchor": "Multiple Weyl and Double-Weyl Points in an Elastic Chiral Lattice: We show that Multiple Weyl and double Weyl points arise in a chiral elastic\nsystem through stacking many two-dimensional honeycomb mechanical structures.\nOn the distinct kz plane, the band structures calculated from tight-binding\nmodel exhibit the presence of Weyl points at Brillouin vertices and double Weyl\nPoints at Brillouin centre. Based on the tight-binding model, we design a\npractical chiral mechanical structure which can be fabricated by current 3D\nprinting technology. The numerical calculation illustrates several Weyl and\ndouble-Weyl points as expected in our analysis of tight-binding model. To\nverify the topological feature, topological charges of every degeneracy are\ncalculated. Within these Weyl points, we theoretically prove that the existence\nof topologically protected surface modes, and their robustness against defects\nare also demonstrated.",
        "positive": "Robust wavefront dislocations of Friedel oscillations in gapped graphene: Friedel oscillation is a well-known wave phenomenon, which represents the\noscillatory response of electron waves to imperfection. By utilizing the\npseudospin-momentum locking in gapless graphene, two recent experiments\ndemonstrate the measurement of the topological Berry phase by corresponding to\nthe unique number of wavefront dislocations in Friedel oscillations. Here, we\nstudy the Friedel oscillations in gapped graphene, in which the\npseudospin-momentum locking is broken. Unusually, the wavefront dislocations do\noccur as that in gapless graphene, which expects the immediate verification in\nthe current experimental condition. The number of wavefront dislocations is\nascribed to the invariant pseudospin winding number in gaped and gapless\ngraphene. This study deepens the understanding of correspondence between\ntopological quantity and wavefront dislocations in Friedel oscillations, and\nimplies the possibility to observe the wavefront dislocations of Friedel\noscillations in intrinsic gapped two-dimensional materials, e.g., transition\nmetal dichalcogenides."
    },
    {
        "anchor": "Resonant Josephson current through a quantum dot: We calculate the DC Josephson current through a semiconducting quantum dot\nwhich is weakly coupled by tunnel barriers to two superconducting reservoirs. A\nBreit-Wigner resonance in the conductance corresponds to a resonance in the\ncritical current, but with a different (non-lorentzian) lineshape.",
        "positive": "Efficient charge modulation in ultrathin LaAlO$_3$-SrTiO$_3$\n  field-effect transistors: At the LaAlO$_3$-SrTiO$_3$ interface, electronic phase transitions can be\ntriggered by modulation of the charge carrier density, making this system an\nexcellent prospect for the realization of versatile electronic devices. Here,\nwe report repeatable transistor operation in locally gated LaAlO$_3$-SrTiO$_3$\nfield-effect devices of which the LaAlO$_3$ dielectric is only four unit cells\nthin, the critical thickness for conduction at this interface. This extremely\nthin dielectric allows a very efficient charge modulation of\n${\\sim}3.2\\times10^{13}$ cm$^{-2}$ within a gate-voltage window of $\\pm1$ V, as\nextracted from capacitance-voltage measurements. These also reveal a large\nstray capacitance between gate and source, presenting a complication for\nnanoscale device operation. Despite the small LaAlO$_3$ thickness, we observe a\nnegligible gate leakage current, which we ascribe to the extension of the\nconducting states into the SrTiO$_3$ substrate."
    },
    {
        "anchor": "Intrinsic and extrinsic anomalous Hall effects in disordered magnetic\n  Weyl semimetal: We study the intrinsic and extrinsic Hall effects in disordered magnetic Weyl\nsemimetals numerically. We show that in Weyl metals, where the Fermi energy\ndeviates from the Weyl point, the Hall and longitudinal conductances exhibit a\nspecific relation, which is distinguished from the well-known relation in\ninteger quantum Hall systems. Around the Weyl point, the Hall conductance\nincreases with increasing longitudinal conductance. This increasing behavior\nindicates the existence of additional contributions to the Hall conductance\nfrom the subbands of Weyl cones besides that from the bulk Berry curvature. We\nalso show that the extrinsic anomalous Hall effect due to the spin scatterers\n(skew scattering) is significantly suppressed in Weyl metals.",
        "positive": "Magneto-optical Kerr and Faraday effects in bilayer antiferromagnetic\n  insulators: Control and detection of antiferromagnetic topological materials are\nchallenging since the total magnetization vanishes. Here we investigate the\nmagneto-optical Kerr and Faraday effects in bilayer antiferromagnetic insulator\nMnBi$_2$Te$_4$. We find that by breaking the combined mirror symmetries with\neither perpendicular electric field or external magnetic moment, Kerr and\nFaraday effects occur. Under perpendicular electric field, antiferromagnetic\ntopological insulators (AFMTI) show sharp peaks at the interband transition\nthreshold, whereas trivial insulators show small adjacent positive and negative\npeaks. Gate voltage and Fermi energy can be tuned to reveal the differences\nbetween AFMTI and trivial insulators. We find that AFMTI with large\nantiferromagnetic order can be proposed as a pure magneto-optical rotator due\nto sizable Kerr (Faraday) angles and vanishing ellipticity. Under external\nmagnetic moment, AFMTI and trivial insulators are significantly different in\nthe magnitude of Kerr and Faraday angles and ellipticity. For the qualitative\nbehaviors, AFMTI shows distinct features of Kerr and Faraday angles when the\nspin configurations of the system change. These phenomena provide new\npossibilities to optically detect and manipulate the layered topological\nantiferromagnets."
    },
    {
        "anchor": "Magnetoresistance and electronic structure of asymmetric GaAs/AlGaAs\n  double quantum wells in the in-plane/tilted magnetic field: Bilayer two-dimensional electron systems formed by a thin barrier in the GaAs\nbuffer of a standard heterostructure were investigated by magnetotransport\nmeasurements. In magnetic fields oriented parallel to the electron layers, the\nmagnetoresistance exhibits an oscillation associated with the depopulation of\nthe higher occupied subband and the field-induced transition into a decoupled\nbilayer. Shubnikov-de Haas oscillations in slightly tilted magnetic fields\nallow to reconstruct the evolution of the electron concentration in the\nindividual subbands as a function of the in-plane magnetic field. The\ncharacteristics of the system derived experimentally are in quantitative\nagreement with numerical self-consistent-field calculations of the electronic\nstructure.",
        "positive": "Topography preserved microwave plasma etching for top-down layer\n  engineering in MoS2 and other van der Waals materials: A generic and universal layer engineering strategy for van der Waals (vW)\nmaterials, scalable and compatible with the current semiconductor technology is\nof paramout importance in realizing all-two-dimensional logic circuits and move\nbeyond the silicon scaling limit. In this letter, we demonstrate a scalable and\nhighly controllable microwave plasma based layer engineering strategy for MoS2\nand other vW materials. Using this technique we etch MoS2 flakes layer-by-layer\nstarting from arbitrary thickness and area down to the mono- or the few-layer\nlimit. From Raman spectroscopy, atomic force microscopy, photoluminescence\nspectroscopy, scanning electron microscopy and transmission electron\nmicroscopy, we confirm that the structural and morphological properties of the\nmaterial have not been compromised. The process preserves the pre-etch layer\ntopography and yields a smooth and pristine-like surface. We explore the\nelectrical properties utilising a field effect transistor geometry and find\nthat the mobility values of our samples are comparable to those of the pristine\nones. The layer removal does not involve any reactive gasses or chemical\nreactions and relies on breaking the weak inter-layer vW interaction making it\na generic technique for a wide spectrum of layered materials and\nheterostructures. We demonstrate the wide applicability of the technique by\nextending it to other systems such as Graphene, h-BN and WSe2. In addition,\nusing the microwave plasma in combination with standard lithography, we\nillustrate a lateral patterning scheme for device fabrication."
    },
    {
        "anchor": "Perturbed Periodic Lattices: Sharp Crossover Between Effective-Mass-Like\n  States and Wannier-Stark-Like Ladders: The concept of Wannier-Stark ladders, describing the equally spaced spectrum\nof a tightly-bound particle in a constant electric field, is generalized to\naccount for arbitrary slowly-varying potentials. It is shown that an abrupt\ntransition exists that separates Wannier-Stark-like from effective-mass-like\nbehavior when the depth of the perturbation becomes equal to the width of the\nband of extended states. For potentials bounded from below, the spectrum\nbifurcates above the critical energy while the wavefunctions detach from the\neffective-mass region and split into two pieces.",
        "positive": "Revealing the nature of excitons in liquid exfoliated monolayer WS2: Transition metal dichalcogenides hold promise for applications in novel\noptoelectronic devices. There is therefore a need for materials that can be\nobtained in large quantities and with well understood optical properties. In\nthis report, we present a thorough photoluminescence (PL) investigations of\nmonolayer tungsten disulphide obtained via liquid phase exfoliation. As shown\nby microscopy studies, the exfoliated nanosheets have dimensions of tens of\nnanometers and thickness of 2.5 monolayers on average. The monolayer content is\nabout 20%. Our studies show that at low temperature the photoluminescence is\ndominated by excitons localized on nanosheet edges. As a consequence, the PL is\nstrongly sensitive to environment and exhibits an enhanced splitting in\nmagnetic field. As the temperature is increased, the excitons are thermally\nexcited out of the defect states and the dominant transition is that of the\nnegatively charged exciton. Furthermore, upon excitation with a circularly\npolarized light, the PL retains a degree of polarization reaching 50% and\ninherited from the valley polarized photoexcited excitons. The studies of PL\ndynamics reveal that the PL lifetime is on the order of 10 ps, probably limited\nby non-radiative processes. Our results underline the potential of liquid\nexfoliated TMD monolayers in large scale optoelectronic devices."
    },
    {
        "anchor": "Magnetization reversal in sub-100nm magnetic tunnel junctions with\n  ultrathin MgO barrier biased along hard axis: We report on room temperature magnetoresistance and low frequency noise in\nsub-100nm elliptic CoFeB/MgO/CoFeB magnetic tunnel junctions with ultrathin\n(0.9nm) barriers. For magnetic fields applied along the hard axis, we observe\ncurrent induced magnetization switching between the antiparallel and parallel\nalignments at DC current densities as low as 4*106A/cm2. We attribute the low\nvalue of the critical current to the influence of localized reductions in the\ntunnel barrier, which affects the current distribution. The analysis of random\ntelegraph noise, which appears in the field interval near a magnetization\nswitch, provides an estimate to the dimension of the pseudo pinholes that\ntrigger the magnetization switching via local spin torque. Micromagnetic\nsimulations qualitatively and quantitatively reproduce the main experimental\nobservations.",
        "positive": "Gate Coupling to Nanoscale Electronics: The realization of single-molecule electronic devices, in which a\nnanometer-scale molecule is connected to macroscopic leads, requires the\nreproducible production of highly ordered nanoscale gaps in which a molecule of\ninterest is electrostatically coupled to nearby gate electrodes. Understanding\nhow the molecule-gate coupling depends on key parameters is crucial for the\ndevelopment of high-performance devices. Here we directly address this,\npresenting two- and three-dimensional finite-element electrostatic simulations\nof the electrode geometries formed using emerging fabrication techniques. We\nquantify the gate coupling intrinsic to these devices, exploring the roles of\nparameters believed to be relevant to such devices. These include the thickness\nand nature of the dielectric used, and the gate screening due to different\ndevice geometries. On the single-molecule (~1nm) scale, we find that device\ngeometry plays a greater role in the gate coupling than the dielectric constant\nor the thickness of the insulator. Compared to the typical uniform nanogap\nelectrode geometry envisioned, we find that non-uniform tapered electrodes\nyield a significant three orders of magnitude improvement in gate coupling. We\nalso find that in the tapered geometry the polarizability of a molecular\nchannel works to enhance the gate coupling."
    },
    {
        "anchor": "Multiple Phases with the Same Quantized Hall Conductance in a\n  Two-Subband System: In a GaAs/AlGaAs two-dimensional electron system with two occupied subbands,\nthe experimentally determined phase diagram in the density-magnetic field plane\nexhibits rich topological features. Ring-like structures are observed at even\ninteger filling factors, in the phase diagram. Even with the identical\nquantized Hall resistance values as those given rise by the ordinary integer\nquantum Hall effect due to the Landau level quantization; the activation\nenergies of these states within the rings are much smaller. These ring\nstructures cannot account for by the simple single particle picture. We argue\nthat ferromagnetic quantum Hall states, due to the interaction of two energy\nlevels with opposite spin and different subband indices, are responsible for\nthese unusual structures.",
        "positive": "Graphene Spin Valve Devices: Graphene - a single atomic layer of graphite - is a recently-found\ntwo-dimensional form of carbon, which exhibits high crystal quality and\nballistic electron transport at room temperature. Soft magnetic NiFe electrodes\nhave been used to inject polarized spins into graphene and a 10% change in\nresistance has been observed as the electrodes switch from the parallel to the\nantiparallel state. This coupled with the fact that a field effect electrode\ncan modulate the conductivity of these graphene films makes them exciting\npotential candidates for spin electronic devices."
    },
    {
        "anchor": "Size dependence of spin-torque switching in perpendicular magnetic\n  tunnel junctions: We simulate the spin torque-induced reversal of the magnetization in thin\ndisks with perpendicular anisotropy at zero temperature. Disks typically\nsmaller than 20 nm in diameter exhibit coherent reversal. A domain wall is\ninvolved in larger disks. We derive the critical diameter of this transition.\nUsing a proper definition of the critical voltage, a macrospin model can\naccount perfectly for the reversal dynamics when the reversal is coherent. The\nsame critical voltage appears to match with the micromagnetics switching\nvoltage regardless of the switching path.",
        "positive": "Resonant Spin Tunneling in Randomly Oriented Nanospheres of Mn$_{12}$\n  Acetate: We report measurements and theoretical analysis of resonant spin tunneling in\nrandomly oriented nanospheres of a molecular magnet. Amorphous nanospheres of\nMn$_{12}$ acetate have been fabricated and characterized by chemical, infrared,\nTEM, X-ray, and magnetic methods. Magnetic measurements have revealed sharp\ntunneling peaks in the field derivative of the magnetization that occur at the\ntypical resonant field values for Mn$_{12}$ acetate. Theoretical analysis is\nprovided that explains these observations. We argue that resonant spin\ntunneling in a molecular magnet can be established in a powder sample, without\nthe need for a single crystal and without aligning the easy magnetization axes\nof the molecules. This is confirmed by re-analyzing the old data on a powdered\nsample of non-oriented micron-size crystals of Mn$_{12}$ acetate. Our findings\ncan greatly simplify the selection of candidates for quantum spin tunneling\namong newly synthesized molecular magnets."
    },
    {
        "anchor": "Monolayer graphene panorama, Majorana modes and Longitudinal\n  conductivity: We take a wide-angle view of the problem of monolayer graphene where the\nvalley-mixing and the spin-degeneracy lifting are assumed to be possible by\nwedging in the requisite ingredients, viz. the atomically sharp scatterers and\nthe strong Rashba coupling dominating over the intrinsic spin-orbit coupling.\nThis leads to eight Majorana-like modes (quasi-particles which are\nself-conjugate) close to the experimentally inaccessible Dirac points. Using\nKubo formula we also show that the semi-classical diffusive (longitudinal)\nconductivity is nearly (2.018 e2/h) at room temperature for the disordered\nsystem. Though this is an overestimation, we have been, never-the-less, able to\nqualitatively capture the fact that the room temperature conductivity of\ngraphene is finite and the contribution to the conductivity arises from the\nmomentum very close to the Dirac points.",
        "positive": "Controlled creation and stability of k\u03c0-skyrmions on a discrete\n  lattice: We determine sizes and activation energies of k{\\pi}-skyrmions on a discrete\nlattice using the Landau- Lifshitz-Gilbert equation and the geodesic nudged\nelastic band method. The employed atomic material parameters are based on the\nskyrmionic material system Pd/Fe/Ir(111). We find that the critical magnetic\nfields for collapse of the 2{\\pi}-skyrmion and 3{\\pi}-skyrmion are very close\nto each other and considerably lower than the critical field of the\n1{\\pi}-skyrmion. The activation energy protecting the structures does not\nstrictly decrease with increasing k as it can be larger for the 3{\\pi}-skyrmion\nthan for the 2{\\pi}-skyrmion depending on the applied magnetic field.\nFurthermore, we propose a method of switching the skyrmion order k by a\nreversion of the magnetic field direction in samples of finite size."
    },
    {
        "anchor": "Size and temperature dependent magnetization of iron nanoclusters: The magnetic behavior of bcc iron nanoclusters, with diameters between 2 and\n8 nm, is investigated by means of spin dynamics (SD) simulations coupled to\nmolecular dynamics (MD-SD), using a distance-dependent exchange interaction.\nFinite-size effects in the total magnetization as well as the influence of the\nfree surface and the surface/core proportion of the nanoclusters are analyzed\nin detail for a wide temperature range, going beyond the cluster and bulk Curie\ntemperatures. Comparison is made with experimental data and with theoretical\nmodels based on the mean-field Ising model adapted to small clusters, and\ntaking into account the influence of low coordinated spins at free surfaces.\nOur results for the temperature dependence of the average magnetization per\natom M(T), including the thermalization of the transnational lattice degrees of\nfreedom, are in very good agreement with available experimental measurements on\nsmall Fe nanoclusters. In contrast, significant discrepancies with experiment\nare observed if the translational degrees of freedom are artificially frozen.\nThe finite-size effects on M(T) are found to be particularly important near the\ncluster Curie temperature. Simulated magnetization above the Curie temperature\nscales with cluster size as predicted by models assuming short-range magnetic\nordering (SRMO). Analytical approximations to the magnetization as a function\nof temperature and size are proposed.",
        "positive": "Dynamics of Vortex Nucleation in Nanomagnets with Broken Symmetry: We investigate fundamental processes that govern dynamics of vortex\nnucleation in sub-100 nm mesoscopic magnets. We focus on a structure with\nbroken symmetry - Pacman-like nanomagnet shape - in which we study\nmicromagnetic behavior both by means of a simple model and numerically. We show\nthat it is possible to establish desired vortex chirality and polarity by\napplying only quasi-static in-plane magnetic field along specific directions.\nWe identify the modes of vortex nucleation that are very robust against\nexternal magnetic field noise. These vortex nucleation modes are common among\nwide range of sub-100 nm magnets with broken rotational symmetry."
    },
    {
        "anchor": "Floquet-Engineered Valley-Topotronics in Kekul$\u00e9\\ $- Y Bond Textured\n  Graphene Superlattice: The exquisite distortion in a Kekul$\\'e\\ $-Y (Kek-Y) superlattice merges the\ntwo inequivalent Dirac cones (from the $K$- and the $K^\\prime$- points) into\nthe highest symmetric $\\Gamma$-point in the hexagonal Brillouin zone. Here we\nreport that a circularly polarised light not only opens up a topological gap at\nthe $\\Gamma$-point but also lifts the valley degeneracy at that point. Endowed\nwith Floquet dynamics and by devising a scheme of high-frequency approximation,\nwe have proposed that the handedness (left/right) in polarised light offers the\npossibility to realise the valley-selective circular dichroism in Kek-Y shaped\ngraphene superlattice. Also, the non-vanishing Berry curvature and enumeration\nof valley resolved Chern number $\\mathcal{C}_{K}/\\mathcal{C}_{K^\\prime}=+1/-1$\nenable us to assign two pseudo-spin flavors (up/down) with the two valleys.\nThereby, the above observations confirm the topological transition suggesting\nthe ease of realising the valley quantum anomalous Hall (VQAH) state within the\nphoton-dressed Kek-Y. These findings further manifest a non-zero optical valley\npolarisation which is maximum at the $\\Gamma$-point. Our paper thus proposes an\noptically switchable topological valley filter which is desirous in the\nevolving landscape of valleytronics.",
        "positive": "The second order nonlinear conductance of a two-dimensional mesoscopic\n  conductor: We have investigated the weakly non-linear quantum transport properties of a\ntwo-dimensional quantum conductor. We have developed a numerical scheme which\nis very general for this purpose. The nonlinear conductance is computed by\nexplicitly evaluating the various partial density of states, the sensitivity\nand the characteristic potential. Interesting spatial structure of these\nquantities are revealed. We present detailed results concerning the crossover\nbehavior of the second order nonlinear conductance when the conductor changes\nfrom geometrically symmetrical to asymmetrical. Other issues of interests such\nas the gauge invariance are also discussed."
    },
    {
        "anchor": "Comment on ''Direct Current in Mesoscopic Rings Induced by\n  High-Frequency Electromagnetic Field'': see cond-mat/0002050",
        "positive": "Preparation of Non-equilibrium Nuclear Spin States in Double Quantum\n  Dots: We theoretically study the dynamic polarization of lattice nuclear spins in\nGaAs double quantum dots containing two electrons. In our prior work [Phys.\nRev. Lett. 104, 226807 (2010)] we identified three regimes of long-term\ndynamics, including the build up of a large difference in the Overhauser fields\nacross the dots, the saturation of the nuclear polarization process associated\nwith formation of so-called \"dark states,\" and the elimination of the\ndifference field. In particular, when the dots are different sizes we found\nthat the Overhauser field becomes larger in the smaller dot. Here we present a\ndetailed theoretical analysis of these problems including a model of the\npolarization dynamics and the development of a new numerical method to\nefficiently simulate semiclassical central-spin problems. When nuclear spin\nnoise is included, the results agree with our prior work indicating that large\ndifference fields and dark states are stable configurations, while the\nelimination of the difference field is unstable; however, in the absence of\nnoise we find all three steady states are achieved depending on parameters.\nThese results are in good agreement with dynamic nuclear polarization\nexperiments in double quantum dots."
    },
    {
        "anchor": "Single Photon Emission from a Plasmonic Light Source Driven by a Local\n  Field-Induced Coulomb Blockade: A hallmark of quantum control is the ability to manipulate quantum emission\nat the nanoscale. Through scanning tunneling microscopy induced luminescence\n(STML) we are able to generate plasmonic light originating from inelastic\ntunneling processes that occur in a few-nanometer thick molecular film of\nC$_{60}$ deposited on Ag(111). Single photon emission, not of excitonic origin,\noccurs with a 1/$e$ lifetime of a tenth of a nanosecond or less, as shown\nthrough Hanbury Brown and Twiss photon intensity interferometry. We have\nperformed tight-binding calculations of the electronic structure for the\ncombined Ag-C$_{60}$-tip system and obtained good agreement with experiment.\nThe tunneling happens through electric field induced split-off states below the\nC$_{60}$ LUMO band, which leads to a Coulomb blockade effect and single photon\nemission. The use of split-off states is shown to be a general technique that\nhas special relevance for narrowband materials with a large bandgap.",
        "positive": "Higher-order topological semimetals and nodal superconductors with an\n  order-two crystalline symmetry: Using a systematic relation between topological gapless phases in three\ndimensions and topological gapped phases in two dimensions, we identify four\ntypes of higher-order topological semimetals or nodal superconductors (HOTS),\nhosting (i) flat zero-energy \"Fermi arcs\" at crystal hinges, (ii) flat\nzero-energy hinge arcs coexisting with surface Dirac cones, (iii) chiral or\nhelical hinge modes, or (iv) flat zero-energy hinge arcs connecting nodes only\nat finite momentum. Bulk-boundary correspondence relates the hinge states to\nthe bulk topology protecting the nodal point or loop. We classify all HOTS for\nall tenfold-way classes with an order-two crystalline (anti-)symmetry, such as\nmirror, twofold rotation, or inversion."
    },
    {
        "anchor": "Spectral and polarization dependencies of luminescence by hot carriers\n  in graphene: The luminescence caused by the interband transitions of hot carriers in\ngraphene is considered theoretically. The dependencies of emission in mid- and\nnear-IR spectral regions versus energy and concentration of hot carriers are\nanalyzed; they are determined both by an applied electric field and a gate\nvoltage. The polarization dependency is determined by the angle between the\npropagation direction and the normal to the graphene sheet. The characteristics\nof radiation from large-scale-area samples of epitaxial graphene and from\nmicrostructures of exfoliated graphene are considered. The averaged over angles\nefficiency of emission is also presented.",
        "positive": "Air Stable Doping and Intrinsic Mobility Enhancement in Monolayer\n  $MoS_{2}$ by Amorphous $TiO_{x}$ Encapsulation: To reduce Schottky-barrier-induced contact and access resistance, and the\nimpact of charged impurity and phonon scattering on mobility in devices based\non 2D transition metal dichalcogenides (TMDs), considerable effort has been put\ninto exploring various doping techniques and dielectric engineering using\n$high-\\kappa$ oxides, respectively. The goal of this work is to demonstrate a\n$high-\\kappa$ dielectric that serves as an effective n-type charge transfer\ndopant on monolayer (ML) molybdenum disulfide ($MoS_{2}$). Utilizing amorphous\ntitanium suboxide (ATO) as the '$high-\\kappa$ dopant', we achieved a contact\nresistance of ~ $180$ ${\\Omega}.{\\mu}m$ which is the lowest reported value for\nML $MoS_{2}$. An ON current as high as $240$ ${\\mu}A/{\\mu}m$ and field effect\nmobility as high as $83$ $cm^2/V-s$ were realized using this doping technique.\nMoreover, intrinsic mobility as high as $102$ $cm^2/V-s$ at $300$ $K$ and $501$\n$cm^2/V-s$ at $77$ $K$ were achieved after ATO encapsulation which are among\nthe highest mobility values reported on ML $MoS_{2}$. We also analyzed the\ndoping effect of ATO films on ML $MoS_{2}$, a phenomenon which is absent when\nstoichiometric $TiO_{2}$ is used, using ab initio density functional theory\n(DFT) calculations which shows excellent agreement with our experimental\nfindings. Based on the interfacial-oxygen-vacancy mediated doping as seen in\nthe case of $high-\\kappa$ ATO - ML $MoS_{2}$, we propose a mechanism for the\nmobility enhancement effect observed in TMD-based devices after encapsulation\nin a $high-\\kappa$ dielectric environment."
    },
    {
        "anchor": "A steep-slope MoS2-nanoribbon MOSFET based on an intrinsic cold-contact\n  effect: We propose a steep-slope MoS2-nanoribbon field-effect transistor that\nexploits a narrow-energy conduction band to intrinsically filter out the\nthermionic tail of the electron energy distribution. We study the device\noperation principle and the performance dependence on the design parameters\nthrough atomistic self-consistent quantum simulations. Our results indicate\nthat the device can provide high ION/IOFF ratios, compatible with electronic\napplications, albeit biased at ultralow voltages of around 0.1 V.",
        "positive": "Repulsive Casimir Effect with Chern insulators: We theoretically predict that the Casimir force in vacuum between two Chern\ninsulator plates can be repulsive (attractive) at long distances whenever the\nsign of the Chern numbers characterizing the two plates are opposite (equal). A\nunique feature of this system is that the sign of the force can be tuned simply\nby turning over one of the plates or alternatively by electrostatic doping. We\ncalculate and take into account the full optical response of the plates and\nargue that such repulsion is a general phenomena for these systems as it relies\non the quantized zero frequency Hall conductivity. We show that achieving\nrepulsion is possible with thin films of Cr-doped (Bi,Sb)$_2$Te$_3$, that were\nrecently discovered to be Chern insulators with quantized Hall conductivity."
    },
    {
        "anchor": "Dynamical detection of Majorana fermions in current-biased nanowires: We analyze the current-biased Shapiro experiment in a Josephson junction\nformed by two one-dimensional nanowires featuring Majorana fermions. Ideally,\nthese junctions are predicted to have an unconventional $4\\pi$-periodic\nJosephson effect and thus only Shapiro steps at even multiples of the driving\nfrequency. Taking additionally into account overlap between the Majorana\nfermions, due to the finite length of the wire, renders the Josephson junction\nconventional for any dc-experiments. We show that probing the current-phase\nrelation in a current biased setup dynamically decouples the Majorana fermions.\nWe find that besides the even integer Shapiro steps there are additional steps\nat odd and fractional values. However, different from the voltage biased case,\nthe even steps dominate for a wide range of parameters even in the case of\nmultiple modes thus giving a clear experimental signature of the presence of\nMajorana fermions.",
        "positive": "Floquet scattering of quadratic band-touching semimetals through a\n  time-periodic potential well: We consider tunneling of quasiparticles through a rectangular quantum well,\nsubject to periodic driving. The quasiparticles are the itinerant charges in\ntwo-dimensional and three-dimensional semimetals having a quadratic\nband-touching (QBT) point in the Brillouin zone. In order to analyze the\ntime-periodic Hamiltonian, we assume a non-adiabatic limit, where the Floquet\ntheorem is applicable. By deriving the Floquet scattering matrices, we chalk\nout the transmission and shot noise spectra of the QBT semimetals. The spectra\nshow Fano resonances, which we identify with the (quasi)bound states of the\nsystems."
    },
    {
        "anchor": "Screening and antiscreening in fullerene-like cages:dipole-field\n  amplification with ionic nanocages: We investigate from first principles screening effects in endohedral\ncomplexes when small molecules, characterized by a finite electronic dipole\nmoment, such as HF, LiF, NaCl, and H$_2$O, are encapsulated into different\nnanoscale cages. We find that screening effects crucially depend on the nature\nof the intramolecular bonds of the cage: screening is maximum in covalent-bond\ncarbon nanocages, while it is reduced in partially-ionic ones. Interestingly,\nin the case of the ionic-bond nanocages, an antiscreening effect is observed:\ndue to the relative displacement of positive and negative ions, induced by the\ndipole moment of the encapsulated molecule, these cages act as dipole-field\namplifiers. Our results open the way to the possibility of tuning the dipole\nmoment of nanocages and of generating electrostatic fields at the nanoscale\nwithout the aid of external potentials. Moreover, we can expect some\ntransferability of the observed screening effects also to nanotubes and 2D\nmaterials.",
        "positive": "Correlated Insulating and Superconducting States in Twisted Bilayer\n  Graphene Below the Magic Angle: The emergence of flat bands and correlated behaviors in 'magic angle' twisted\nbilayer graphene (tBLG) has sparked tremendous interest, though many aspects of\nthe system are under intense debate. Here we report observation of both\nsuperconductivity and the Mott-like insulating state in a tBLG device with a\ntwist angle of approximately 0.93, which is smaller than the magic angle by\n15%. At an electron concentration of +/-5 electrons per moire unit cell, we\nobserve a narrow resistance peak with an activation energy gap of approximately\n0.1 meV, indicating the existence of an additional correlated insulating state.\nThis is consistent with theory predicting the presence of a high-energy band\nwith an energetically flat dispersion. At a doping of +/-12 electrons per moire\nunit cell we observe a resistance peak due to the presence of Dirac points in\nthe spectrum. Our results reveal that the magic range of tBLG is in fact larger\nthan what is previously expected, and provide a wealth of new information to\nhelp decipher the strongly correlated phenomena observed in tBLG."
    },
    {
        "anchor": "Accessing phonon polaritons in hyperbolic crystals by ARPES: Recently studied hyperbolic materials host unique phonon-polariton (PP)\nmodes. The ultra-short wavelengths of these modes, which can be much smaller\nthan those of conventional exciton-polaritons, are of high interest for extreme\nsub-diffraction nanophotonics schemes. Polar hyperbolic materials such as\nhexagonal boron nitride can be used to realize strong long-range coupling\nbetween PP modes and extraneous charge degrees of freedom. The latter, in turn,\ncan be used to control and probe PP modes. Of special interest is coupling\nbetween PP modes and plasmons in an adjacent graphene sheet, which opens the\ndoor to accessing PP modes by angle-resolved photoemission spectroscopy\n(ARPES). A rich structure in the graphene ARPES spectrum due to PP modes is\npredicted, providing a new probe of PP modes and their coupling to graphene\nplasmons.",
        "positive": "Determination of Out-of-plane Spin Polarization of Topological Surface\n  States by Spin Hall Effect Tunneling Spectroscopy: Determining the detailed spin texture of topological surface states is\nimportant when one wants to apply topological insulators in spintronic devices.\nIn principle, the in-plane spin component of the surface states can be measured\nby a method analogous to the so-called Meservey-Tedrow technique. In the\npresent work we suggest that the out-of-plane spin component can be determined\nby spin Hall effect tunneling spectroscopy. We derive an analytical formula\nthat allows to extract the out-of-plane spin component from spin Hall effect\ntunneling spectra. We test our formula using realistic tight-binding models of\nBi$_2$Se$_3$ and Sb$_2$Te$_3$. We demonstrate that the extracted out-of-plane\nspin polarization is in very good agreement with the actual out-of-plane spin\npolarization."
    },
    {
        "anchor": "Spin-orbit interaction in 2D Dirac-like and Kane semiconductors: The single particle equations describing motion of carriers in external\npotential in 2D Dirac-like and Kane intrinsic semiconductors are obtained\nwithin second quantization method. The terms renormalizing external potential\nin these equations, referred to as spin-orbit (SO) terms, are compared with\ntheir classical counterpart. The well-known expression for SO obtained in\nrelativistic Dirac theory arises in considered approach in the second order in\n$\\gamma k / E_g$ ($\\gamma$ - characteristic velocity, $E_g$ - energy gap)\nparameter if electron-hole pair production terms are neglected. It is shown\nthat in Kane problem the modifying terms are of standard SO functional\nDirac-like form only for electrons in the case of ``positive'' energy gap and\nfor light holes in semiconductors with ``negative'' energy gap. The general\nexpression for renormalizing terms has in all cases non-local character. The\narising of correction terms to single particle potentials which do not depend\non band parameters is demonstrated for 2D gapless Dirac problem (graphene) and\nfor Kane model. The origin of such ``topological'' terms is attributed to the\npresence of degenerate bands in considered problems.",
        "positive": "Gate-controlled proximity magnetoresistance in In1-xGaxAs/(Ga,Fe)Sb\n  bilayer heterostructures: The magnetic proximity effect (MPE), ferromagnetic coupling at the interface\nof magnetically dissimilar layers, attracts much attention as a promising\npathway for introducing ferromagnetism into a high-mobility non-magnetic\nconducting channel. Recently, our group found giant proximity magnetoresistance\n(PMR), which is caused by MPE at an interface between a non-magnetic\nsemiconductor InAs quantum well (QW) layer and a ferromagnetic semiconductor\n(Ga,Fe)Sb layer. The MPE in the non-magnetic semiconductor can be modulated by\napplying a gate voltage and controlling the penetration of the electron\nwavefunction in the InAs QW into the neighboring insulating ferromagnetic\n(Ga,Fe)Sb layer. However, optimal conditions to obtain strong MPE at the\nInAs/(Ga,Fe)Sb interface have not been clarified. In this paper, we\nsystematically investigate the PMR properties of In1-xGaxAs (x = 0%, 5%, 7.5%,\nand 10%) / (Ga,Fe)Sb bilayer semiconductor heterostructures under a wide range\nof gate voltage. The inclusion of Ga alters the electronic structures of the\nInAs thin film, in particular changing the effective mass and the QW potential\nof electron carriers. Our experimental results and theoretical analysis of the\nPMR in these In1-xGaxAs/(Ga,Fe)Sb heterostructures show that the MPE depends\nnot only on the degree of penetration of the electron wavefunction into\n(Ga,Fe)Sb but also on the electron density. These findings help us to unveil\nthe microscopic mechanism of MPE in semiconductor-based\nnon-magnetic/ferromagnetic heterojunctions."
    },
    {
        "anchor": "Plasmon damping rates in Coulomb-coupled two-dimensional layers in a\n  heterostructure: The Coulomb excitations of charge density oscillation are calculated for a\ndouble-layer heterostructure. Specifically, we consider two-dimensional (2D)\nlayers of silicene and graphene on a substrate. From the obtained surface\nresponse function, we calculated the plasmon dispersion relations which\ndemonstrate the way in which the Coulomb coupling renormalizes the plasmon\nfrequencies. Additionally, we present a novel result for the damping rates of\nthe plasmons in this Coulomb coupled heterostructure and compare these results\nas the separation between layers is varied.",
        "positive": "Observation of superconducting phase transition in InN: InN superconductivity is very special among III-V semiconductors, because\nother III-V semiconductor (like GaAs, GaN, InP, InAs etc.) usually lacks strong\ncovalent bonding and seldom shows superconductivity at low-temperature. In this\npaper, via current-voltage(I-V) measurement, we probe the superconducting phase\ntransitions in InN. The possible connection with those chemical-unstable phase\nseparated inclusions, like metallic indium or In2O3, was removed by HCl acid\netching. It finds InN samples can show different phase transition behaviors.\nThe vortex-glass (VG) to liquid transition, which is typical in type-II\nsuperconductors, is observed in the sample with large InN grain size. In\ncontrast, the small grain-sized sample's superconducting properties are\nsensitive to acid etching, shows a transition into a non-zero resistance state\nat the limit of temperature approaches zero. Our work suggests that the grain\nsize and inter-grain coupling may be two key factors for realizing InN\nsuperconductivity. InN superconductivity can become robust and chemical stable\nif the grain size and inter-grain coupling both are large enough."
    },
    {
        "anchor": "The role of temperature on defect diffusion and nanoscale patterning in\n  graphene: Graphene is of great scientific interest due to a variety of unique\nproperties such as ballistic transport, spin selectivity, the quantum hall\neffect, and other quantum properties. Nanopatterning and atomic scale\nmodifications of graphene are expected to enable further control over its\nintrinsic properties, providing ways to tune the electronic properties through\ngeometric and strain effects, introduce edge states and other local or extended\ntopological defects, and sculpt circuit paths. The focused beam of a scanning\ntransmission electron microscope (STEM) can be used to remove atoms, enabling\nmilling, doping, and deposition. Utilization of a STEM as an atomic scale\nfabrication platform is increasing; however, a detailed understanding of\nbeam-induced processes and the subsequent cascade of aftereffects is lacking.\nHere, we examine the electron beam effects on atomically clean graphene at a\nvariety of temperatures ranging from 400 to 1000 C. We find that temperature\nplays a significant role in the milling rate and moderates competing processes\nof carbon adatom coalescence, graphene healing, and the diffusion (and\nrecombination) of defects. The results of this work can be applied to a wider\nrange of 2D materials and introduce better understanding of defect evolution in\ngraphite and other bulk layered materials.",
        "positive": "Raman-scattering study of the phonon dispersion in twisted bi-layer\n  graphene: Bi-layer graphene with a twist angle \\theta\\ between the layers generates a\nsuperlattice structure known as Moir\\'{e} pattern. This superlattice provides a\n\\theta-dependent q wavevector that activates phonons in the interior of the\nBrillouin zone. Here we show that this superlattice-induced Raman scattering\ncan be used to probe the phonon dispersion in twisted bi-layer graphene (tBLG).\nThe effect reported here is different from the broadly studied double-resonance\nin graphene-related materials in many aspects, and despite the absence of\nstacking order in tBLG, layer breathing vibrations (namely ZO' phonons) are\nobserved."
    },
    {
        "anchor": "Topological protection of photonic mid-gap cavity modes: Defect modes in two-dimensional periodic photonic structures have found use\nin a highly diverse set of optical devices. For example, photonic crystal\ncavities confine optical modes to subwavelength volumes and can be used for\nPurcell enhancement of nonlinearity, lasing, and cavity quantum\nelectrodynamics. Photonic crystal fiber defect cores allow for supercontinuum\ngeneration and endlessly-single-mode fibers with large cores. However, these\nmodes are notoriously fragile: small changes in the structure can lead to\nsignificant detuning of resonance frequency and mode volume. Here, we show that\na photonic topological crystalline insulator structure can be used to\ntopologically protect the resonance frequency to be in the middle of the band\ngap, and therefore minimize the mode volume of a two-dimensional photonic\ndefect mode. We experimentally demonstrate this in a femtosecond-laser-written\nwaveguide array, a geometry akin to a photonic crystal fiber. The topological\ndefect modes are determined by a topological invariant that protects\nzero-dimensional states (defect modes) embedded in a two-dimensional\nenvironment; a novel form of topological protection that has not been\npreviously demonstrated.",
        "positive": "Adiabatically Induced Orbital Magnetization: A semiclassical theory for the orbital magnetization due to adiabatic\nevolutions of Bloch electronic states is proposed. It renders a unified theory\nfor the periodic-evolution pumped orbital magnetization and the orbital\nmagnetoelectric response in insulators by revealing that these two phenomena\nare the only instances where the induced magnetization is gauge invariant. This\ntheory also accounts for the electric-field induced intrinsic orbital\nmagnetization in two-dimensional metals and Chern insulators. We illustrate the\norbital magnetization pumped by microscopic local rotations of atoms, which\ncorrespond to phonon modes with angular momentum, in toy models based on\nhoneycomb lattice, and the results are comparable to the pumped spin\nmagnetization via strong Rashba spin orbit coupling. We also show the vital\nrole of the orbital magnetoelectricity in validating the Mott relation between\nthe intrinsic nonlinear anomalous Hall and Ettingshausen effects."
    },
    {
        "anchor": "Dynamics of Domain Wall in a Biaxial Ferromagnet With Spin-torque: The dynamics of the domain wall (DW) in a biaxial ferromagnet interacting\nwith a spin-polarized current are described by sine-gordon (SG) equation\ncoupled with Gilbert damping term in this paper. Within our frame-work of this\nmodel, we obtain a threshold of the current in the motion of a single DW with\nthe perturbation theory on kink soliton solution to the corresponding\nferromagnetic system, and the threshold is shown to be dependent on the Gilbert\ndamping term. Also, the motion properties of the DW are discussed for the zero-\nand nonzero-damping cases, which shows that our theory to describe the dynamics\nof the DW are self-consistent.",
        "positive": "From triple-point materials to multiband nodal links: We study a class of topological materials which in their momentum-space band\nstructure exhibit three-fold degeneracies known as triple points. Focusing\nspecifically on $\\mathcal{P}\\mathcal{T}$-symmetric crystalline solids with\nnegligible spin-orbit coupling, we find that such triple points can be\nstabilized by little groups containing a three-, four- or six-fold rotation\naxis, and we develop a classification of all possible triple points as type A\nvs. type B according to the absence vs. presence of attached nodal-line arcs.\nFurthermore, by employing the recently discovered non-Abelian band topology, we\nargue that a rotation-symmetry-breaking strain transforms type-A triple points\ninto multiband nodal links. Although multiband nodal-line compositions were\npreviously theoretically conceived and related to topological monopole charges,\na practical condensed-matter platform for their manipulation and inspection has\nhitherto been missing. By reviewing the known triple-point materials with weak\nspin-orbit coupling, and by performing first-principles calculations to predict\nnew ones, we identify suitable candidates for the realization of multiband\nnodal links in applied strain. In particular, we report that an ideal compound\nto study this phenomenon is Li$_2$NaN, in which the conversion of triple points\nto multiband nodal links facilitates largely tunable density of states and\noptical conductivity with doping and strain, respectively."
    },
    {
        "anchor": "Topology reconstruction for asymmetric systems by isomorphic mapping or\n  perturbation approximation: The systems without symmetries, e.g. the internal or spatial symmetry, are\ngenerally thought to be improper for topological study and no conventional\nintegral topological invariant can be well defined. In this work, with\nmulti-band asymmetric Rice-Mele-like systems as examples, we show that the\ntopology of all gaps can be reconstructed by two general methods and a new\nintegral topological invariant, i.e. the renormalized real-space winding\nnumber, can properly characterise the topology of such systems. For the first\nmethod, an isomorphic mapping relationship between a Rice-Mele-like system and\nits chiral counterpart is constructed, which accounts for the topology\nreconstruction at half-filling gaps. For the second method, the Hilbert space\nof asymmetric systems could be reduced into degenerate subspaces by\nperturbation approximation, so that the topology in subspaces accounts for the\ntopology reconstruction at fractional-filling gaps. The perturbation-based\ntopology exhibits extraordinary robustness since it even exists beyond the weak\nperturbation limit. We also show that both methods can be widely used for other\nasymmetric systems, e.g. the two-dimensional (2D) Rice-Mele systems and the\nsuperconductor systems. At last, for the asymmetric photonic systems, we\npredict different topological edge states by our topology-reconstruction theory\nand experimentally observe them in the laboratory, which agree with each other\nvery well. Our findings open a door for investigating new topological phenomena\nin asymmetric systems by various topological reconstruction methods which\nshould greatly expand the category of topology study.",
        "positive": "Imaging at the mesoscale (LEEM, PEEM): *To be published in Springer Handbook of Surface Science (Springer Verlag)\n[Preprint]*\n  The capability to display images containing chemical, magnetic and structural\ninformation and to perform spectroscopy and diffraction from a {\\mu}m-sized\narea makes cathode lens electron microscopy one of the most used and reliable\ntechniques to analyze surfaces at the mesoscale. Thanks to its versatility,\nLEEM/PEEM systems are currently employed to study model systems in the fields\nof nanotechnology, nanomagnetism, material science, catalysis, energy storage,\nthin films and 2D materials. In the following chapter, we will present a brief\nbut complete review of this class of instruments. After an historical\ndigression in the introducing section, we will show first the basic operating\nprinciples of a simple setup and then the elements that can be added to improve\nthe performances. Later, two sections will be dedicated to LEEM and PEEM\nrespectively. In both cases, a theoretical discussion on the contrast\nmechanisms will prelude to a showcase of the operating modes of the instrument,\nwith clear examples that will show the best performances available nowadays.\nFinally, a brief discussion about the future developments of cathode lens\nelectron microscopy will close the chapter."
    },
    {
        "anchor": "Distributed-element circuit model of edge magnetoplasmon transport: We report experimental and theoretical studies of edge magnetoplasmon (EMP)\ntransport in quantum Hall (QH) devices. We develop a model that allows us to\ncalculate the transport coefficients of EMPs in QH devices with various\ngeometries. In our model, a QH system is described as a chiral\ndistributed-element (CDE) circuit, where the effects of Coulomb interaction are\nrepresented by an electrochemical capacitance distributed along unidirectional\ntransmission lines. We measure the EMP transport coefficients through single-\nand coupled-edge channels, a quantum point contact, and single- and\ndouble-cavity structures. These measured transmission spectra can be reproduced\nwell by simulations using the corresponding CDE circuits. By fitting the\nexperimental results with the simulations, we deduce the circuit parameters\nthat characterize the electrostatic environment around the edge channels in a\nrealistic QH system. The observed gate-voltage dependences of the EMP transport\nproperties in gate-defined structures are explained in terms of the gate tuning\nof the circuit parameters in CDE circuits.",
        "positive": "Pairwise annihilation of Weyl nodes induced by magnetic fields in the\n  Hofstadter regime: Weyl semimetal, which does not require any symmetry except translation for\nprotection, is a robust gapless state of quantum matters in three dimensions.\nWhen translation symmetry is preserved, the only way to destroy a Weyl\nsemimetal state is to bring two Weyl nodes of opposite chirality close to each\nother to annihilate pairwise. An external magnetic field can destroy a pair of\nWeyl nodes (which are separated by a momentum space distance $2k_0$) of\nopposite chirality, when the magnetic length $l_B$ becomes close to or smaller\nthan the inverse separation $1/2k_0$. In this work, we investigate pairwise\nannihilation of Weyl nodes induced by external magnetic field which ranges all\nthe way from small to a very large value in the Hofstadter regime $l_B \\sim a$.\nWe show that this pairwise annihilation in a WSM featuring two Weyl nodes leads\nto the emergence of either a normal insulator or a layered Chern insulator. In\nthe case of a Weyl semimetal with multiple Weyl nodes, the potential for\ngenerating a variety of states through external magnetic fields emerges. Our\nstudy introduces a straightforward and intuitive representation of the pairwise\nannihilation process induced by magnetic fields, enabling accurate predictions\nof the phases that may appear after pairwise annihilation of Weyl nodes."
    },
    {
        "anchor": "Non-equilibrium and proximity effects in superconductor-normal metal\n  junctions: We study the consequences of non-equilibrium heating and inverse proximity\neffect in normal metal - insulator - superconductor - insulator - normal metal\n(NISIN) junctions with a simple quasi-one-dimensional model. We especially\nfocus on observables and parameter regions that are of interest in the design\nof SINIS coolers with quasiparticle traps. We present numerical results\ncalculated by solving the Usadel equation and also present analytical\napproximations in two limiting cases: a short junction with a non-negligible\nresistance in both ends and a long junction with a transparent contact at one\nend.",
        "positive": "Nonlinear response of biased bilayer graphene at terahertz frequencies: A density-matrix formalism within the length gauge is developed to calculate\nthe nonlinear response of both doped and undoped biased bilayer graphene (BBLG)\nat terahertz frequencies. Employing a tight-binding model, we derive an\neffective two-band Hamiltonian with which we calculate the conduction and\nvalence band dispersion, as well as their respective Bloch states. We then\nsolve for the dynamic equations of the density matrix elements, allowing for\nthe calculation of the intraband and interband current densities and the\ntransmitted and reflected terahertz fields. We find that for undoped BBLG with\na gap size of 4 meV, the reflected field exhibits a third harmonic amplitude\nthat is 45% of the fundamental in the reflected field (0.07% of the incident\nfield fundamental) for an incident 1 THz single-cycle pulse with a field\namplitude of 2.0 kV/cm. We find for doped BBLG, although the dispersion becomes\nhighly nonparabolic as a bias is applied, the third harmonic is a maximum of 8%\nof the fundamental in the reflected field (0.56% of the incident field\nfundamental) when there is no bias and diminishes with an increase in bias."
    },
    {
        "anchor": "The effect of superconducting fluctuations on the ac conductivity of a\n  2D electron system in the diffusive regime: We report a complete analytical expression for the one-loop correction to the\nac conductivity $\\sigma(\\omega)$ of a disordered two-dimensional electron\nsystem in the diffusive regime. The obtained expression includes the weak\nlocalization and Altshuler-Aronov corrections as well as the corrections due to\nsuperconducting fluctuations above superconducting transition temperature. The\nderived expression has no $1/(i\\omega)$ divergency in the static limit,\n$\\omega\\to 0$, in agreement with general expectations for the normal state\nconductivity of a disordered electron system.",
        "positive": "Cooling and squeezing via quadratic optomechanical coupling: We explore the physics of optomechanical systems in which an optical cavity\nmode is coupled parametrically to the square of the position of a mechanical\noscillator. We derive an effective master equation describing two-phonon\ncooling of the mechanical oscillator. We show that for high temperatures and\nweak coupling, the steady-state phonon number distribution is non-thermal\n(Gaussian) and that even for strong cooling the mean phonon number remains\nfinite. Moreover, we demonstrate how to achieve mechanical squeezing by driving\nthe cavity with two beams. Finally, we calculate the optical output and\nsqueezing spectra. Implications for optomechanics experiments with the\nmembrane-in-the-middle geometry or ultracold atoms in optical resonators are\ndiscussed."
    },
    {
        "anchor": "Zone folding induced topological insulators in phononic crystals: This letter investigates a flow-free, pseudospin-based acoustic topological\ninsulator. Zone folding, a strategy originated from photonic crystal, is used\nto form double Dirac cones in phononic crystal. The lattice symmetry of the\nphononic crystal is broken by tuning the size of the center \"atom\" of the unit\ncell in order to open the nontrivial topological gap. Robust sound one-way\npropagation is demonstrated both numerically and experimentally. This study\nprovides a flexible approach for realizing acoustic topological insulators,\nwhich are promising for applications such as noise control and waveguide\ndesign.",
        "positive": "Zitterbewegung-mediated RKKY coupling in topological insulator thin\n  films: The dynamics of itinerant electrons in topological insulator (TI) thin films\nis investigated using a multi-band decomposition approach. We show that the\nelectron trajectory in the 2D film is anisotropic and confined within a\ncharacteristic region. Remarkably, the confinement and anisotropy of the\nelectron trajectory are associated with the topological phase transition of the\nTI system, which can be controlled by tuning the film thickness and/or applying\nan in-plane magnetic field. Moreover, persistent electron wavepacket\noscillation can be achieved in the TI thin film system at the phase transition\npoint, which may assist in the experimental detection of the jitter motion\n(Zitterbewegung). The implications of the microscopic picture of electron\nmotion in explaining other transport-related effects, e.g., electron-mediated\nRKKY coupling in the TI thin film system, are also discussed."
    },
    {
        "anchor": "Comment on `Vacuum Rabi Splitting in a Semiconductor Circuit QED System'\n  by Toida et al., Phys. Rev. Lett. 110, 066802 - Published 6 February 2013: Toida et al. claim in their recent article [Phys. Rev. Lett. 110, 066802\n(2013)] that they `report a direct observation of vacuum Rabi splitting in a\nGaAs/AlGaAs double quantum dot (DQD) based charge qubit coupled with a\nsuperconducting coplanar waveguide (CPW) resonator'. In this comment, we\nchallenge the main claims made in their paper and show that their results: a)\ndo not provide any evidence of vacuum Rabi oscillations and b) do not provide\nany direct evidence of vacuum Rabi splitting.",
        "positive": "Time Evolution of Electron Waves in Graphene Superlattices: The time evolution of electron waves in graphene superlattices is studied\nusing both microscopic and 'effective medium' formalisms. The numerical\nsimulations reveal that in a wide range of physical scenarios it is possible to\nneglect the granularity of the superlattice and characterize the electron\ntransport using a simple effective Hamiltonian. It is verified that as general\nrule the continuum approximation is rather accurate when the initial state is\nless localized than the characteristic spatial period of the superlattice. This\nproperty holds even when the microsocopic electric potential has a strong\nspatial modulation or in presence of interfaces between different\nsuperlattices. Detailed examples are given both of the time evolution of\ninitial electronic states and of the propagation of stationary states in the\ncontext of wave scattering. The theory also confirms that electrons propagating\nin tailored graphene superlattices with extreme anisotropy experience virtually\nno diffraction."
    },
    {
        "anchor": "Realization of Nearly Dispersionless Bands with Strong Orbital\n  Anisotropy from Destructive Interference in Twisted Bilayer MoS2: Recently, the twist angle between adjacent sheets of stacked van der Waals\nmaterials emerged as a new knob to engineer correlated states of matter in\ntwo-dimensional heterostructures in a controlled manner, giving rise to\nemergent phenomena such as superconductivity or correlated insulating states.\nHere,we use an ab initio based approach to characterize the electronic\nproperties of twisted bilayer MoS2. We report that, in marked contrast to\ntwisted bilayer graphene, slightly hole-doped MoS2 realizes a strongly\nasymmetric px-py Hubbard model on the honeycomb lattice, with two almost\nentirely dispersionless bands emerging due to destructive interference. We\nstudy the collective behavior of twisted bilayer MoS2 in the presence of\ninteractions, and characterize an array of different magnetic and\norbitally-ordered correlated phases,which may be susceptible to quantum\nfluctuations giving rise to exotic, purely quantum, states of matter.",
        "positive": "Magneto-optics of monolayer and bilayer graphene: The optical conductivity of graphene and bilayer graphene in quantizing\nmagnetic fields is studied. Both dynamical conductivities, longitudinal and\nHall's, are analytically evaluated. The conductivity peaks are explained in\nterms of electron transitions. Correspondences between the transition\nfrequencies and the magneto-optical features are established using the\ntheoretical results. The main optical transitions obey the selection rule with\n$\\Delta n=1$ for the Landau number $n$. The Faraday rotation and light\ntransmission in the quantizing magnetic fields are calculated. The effects of\ntemperatures and magnetic fields on the chemical potential are considered.\n\\pacs{71.20.Nr, 78.20.Ci, 78.20.Bh}"
    },
    {
        "anchor": "Unified description of the Zitterbewegung for spintronic, graphene and\n  superconducting systems: We present a unified treatment of Zitterbewegung phenomena for a wide class\nof systems including spintronic, graphene, and superconducting systems. We\nderive an explicit expression for the time-dependence of the position operator\nof the quasiparticles which can be decomposed into a mean part and an\noscillatory term. The latter corresponds to the Zitterbewegung. To apply our\nresult for different systems one needs to use only vector algebra instead of\nthe more complicated operator algebra.",
        "positive": "Role of Dzyaloshinskii-Moriya interaction for magnetism in\n  transition-metal chains at Pt step-edges: We explore the emergence of chiral magnetism in one-dimensional monatomic Mn,\nFe, and Co chains deposited at the Pt(664) step-edge carrying out an ab-initio\nstudy based on density functional theory (DFT). The results are analyzed\nemploying several models: (i) a micromagnetic model, which takes into account\nthe Dzyaloshinskii-Moriya interaction (DMI) besides the spin stiffness and the\nmagnetic anisotropy energy, and (ii) the Fert-Levy model of the DMI for diluted\nmagnetic impurities in metals. Due to the step-edge geometry, the direction of\nthe Dzyaloshinskii vector (D-vector) is not predetermined by symmetry and\npoints in an off-symmetry direction. For the Mn chain we predict a long-period\ncycloidal spin-spiral ground state of unique rotational sense on top of an\notherwise atomic-scale antiferromagnetic phase. The spins rotate in a plane\nthat is tilted relative to the Pt surface by $62^\\circ$ towards the upper step\nof the surface. The Fe and Co chains show a ferromagnetic ground state since\nthe DMI is too weak to overcome their respective magnetic anisotropy barriers.\nBeyond the discussion of the monatomic chains we provide general expressions\nrelating ab-initio results to realistic model parameters that occur in a\nspin-lattice or in a micromagnetic model. We prove that a planar homogeneous\nspiral of classical spins with a given wave vector rotating in a plane whose\nnormal is parallel to the D-vector is an exact stationary state solution of a\nspin-lattice model for a periodic solid that includes Heisenberg exchange and\nDMI. The validity of the Fert-Levy model for the evaluation of micromagnetic\nDMI parameters and for the analysis of ab-initio calculations is explored for\nchains. The results suggest that some care has to be taken when applying the\nmodel to infinite periodic one-dimensional systems."
    },
    {
        "anchor": "Pressure variation of Luttinger liquids parameters in single wall carbon\n  nanotubes networks: We measure electrical transport on networks of single wall nanotube of\ndifferent origin as a function of temperature T, voltage V and pressure P . We\nobserve Luttinger liquid (LL) behavior, a conductance T^alpha and a dynamic\nconductance V^alpha . We observe a sample dependent P variation of the alpha\nparameters, interpreted as fermi level changes due to pressure induced charge\ntransfer. We show how, through standard four-leads and crossed configuration\nmethods, it is possible to determine alpha_bulk and alpha_end, respectively. We\nstudy and discuss the pressure and doping level dependences of the number of\nchannels N, the LL parameter g and the intra-rope tube-tube coupling constant U .",
        "positive": "Simulation electronic thermes of two atoms molecules: In the first order of the perturbation theory, the correction to the\nelectronic terms of a diatomic molecule is calculated taking into account the\nPauli principle."
    },
    {
        "anchor": "Quantum Computation and Spin Electronics: In this chapter we explore the connection between mesoscopic physics and\nquantum computing. After giving a bibliography providing a general introduction\nto the subject of quantum information processing, we review the various\napproaches that are being considered for the experimental implementation of\nquantum computing and quantum communication in atomic physics, quantum optics,\nnuclear magnetic resonance, superconductivity, and, especially, normal-electron\nsolid state physics. We discuss five criteria for the realization of a quantum\ncomputer and consider the implications that these criteria have for quantum\ncomputation using the spin states of single-electron quantum dots. Finally, we\nconsider the transport of quantum information via the motion of individual\nelectrons in mesoscopic structures; specific transport and noise measurements\nin coupled quantum dot geometries for detecting and characterizing\nelectron-state entanglement are analyzed.",
        "positive": "Diamagnetism in disordered graphene: The orbital magnetism is studied in graphene monolayer within the effective\nmass approximation. In models of short-range and long-range disorder, the\nmagnetization is calculated with self-consistent Born approximation. In the\nzero-field limit, the susceptibility becomes highly diamagnetic around zero\nenergy, while it has a long tail proportional to the inverse of the Fermi\nenergy. We demonstrated how the magnetic oscillation vanishes and converges to\nthe susceptibility, on going from a strong-field regime to zero-field. The\nbehavior at zero energy is shown to be highly singular."
    },
    {
        "anchor": "Non-linear resistivity and heat dissipation in monolayer graphene: We have experimentally studied the nonlinear nature of electrical conduction\nin monolayer graphene devices on silica substrates. This nonlinearity manifests\nitself as a nonmonotonic dependence of the differential resistance on applied\nDC voltage bias across the sample. At temperatures below ~70K, the differential\nresistance exhibits a peak near zero bias that can be attributed to\nself-heating of the charge carriers. We show that the shape of this peak arises\nfrom a combination of different energy dissipation mechanisms of the carriers.\nThe energy dissipation at higher carrier temperatures depends critically on the\nlength of the sample. For samples longer than 10um the heat loss is shown to be\ndetermined by optical phonons at the silica-graphene interface.",
        "positive": "Stochastic Gross-Pitaevskii Equation for the Dynamical Thermalization of\n  Bose-Einstein Condensates: We present a theory for the description of energy relaxation in a\nnonequilibrium condensate of bosonic particles. The approach is based on\ncoupling to a thermal bath of other particles (e.g., phonons in a crystal, or\nnoncondensed atoms in a cold atom system), which are treated with a Monte Carlo\ntype approach. Together with a full account of particle-particle interactions,\ndynamic driving, and particle loss, this offers a complete description of\nrecent experiments in which Bose-Einstein condensates are seen to relax their\nenergy as they propagate in real space and time. As an example, we apply the\ntheory to the solid-state system of microcavity exciton polaritons, in which\nnonequilibrium effects are particularly prominent."
    },
    {
        "anchor": "Scaling Theory of Topological Phase Transitions: Topologically ordered systems are characterized by topological invariants\nthat are often calculated from the momentum space integration of a certain\nfunction that represents the curvature of the many-body state. The curvature\nfunction may be Berry curvature, Berry connection, or other quantities\ndepending on the system. Akin to stretching a messy string to reveal the number\nof knots it contains, a scaling procedure is proposed for the curvature\nfunction in inversion symmetric systems, from which the topological phase\ntransition can be identified from the flow of the driving energy parameters\nthat control the topology (hopping, chemical potential, etc.) under scaling. At\nan infinitesimal operation, one obtains the renormalization group (RG)\nequations for the driving energy parameters. A length scale defined from the\ncurvature function near the gap-closing momentum is suggested to characterize\nthe scale invariance at critical points and fixed points, and displays a\nuniversal critical behavior in a variety of systems examined.",
        "positive": "Nonequilibrium Langevin Approach to Quantum Optics in Semiconductor\n  Microcavities: Recently the possibility of generating nonclassical polariton states by means\nof parametric scattering has been demonstrated. Excitonic polaritons propagate\nin a complex interacting environment and contain real electronic excitations\nsubject to scattering events and noise affecting quantum coherence and\nentanglement. Here we present a general theoretical framework for the realistic\ninvestigation of polariton quantum correlations in the presence of coherent and\nincoherent interaction processes. The proposed theoretical approach is based on\nthe {\\em nonequilibrium quantum Langevin approach for open systems} applied to\ninteracting-electron complexes described within the dynamics controlled\ntruncation scheme. It provides an easy recipe to calculate multi-time\ncorrelation functions which are key-quantities in quantum optics. As a first\napplication, we analyze the build-up of polariton parametric emission in\nsemiconductor microcavities including the influence of noise originating from\nphonon induced scattering."
    },
    {
        "anchor": "Distinct magnetic field dependence of N\u00e9el skyrmion sizes in ultrathin\n  nanodots: We investigate the dependence of the N\\'eel skyrmion size and stability on\nperpendicular magnetic field in ultrathin circular magnetic dots with\nout-of-plane anisotropy and interfacial Dzyaloshinskii-Moriya exchange\ninteraction. Our results show the existence of two distinct dependencies of the\nskyrmion radius on the applied field and dot size. In the case of skyrmions\nstable at zero field, their radius strongly increases with the field applied\nparallel to the skyrmion core until skyrmion reaches the metastability region\nand this dependence slows down. More common metastable skyrmions demonstrate a\nweaker increase of their size as a function of the field until some critical\nfield value at which these skyrmions drastically increase in size showing a\nhysteretic behavior with coexistence of small and large radius skyrmions and\nsmall energy barriers between them. The first case is also characterized by a\nstrong dependence of the skyrmion radius on the dot diameter, while in the\nsecond case this dependence is very weak.",
        "positive": "Quantum transport in honeycomb lattice ribbons with armchair and zigzag\n  edges coupled to semi-infinite linear chain leads: We study quantum transport in honeycomb lattice ribbons with either armchair\nor zigzag edges. The ribbons are coupled to semi-infinite linear chains serving\nas the input and output leads and we use a tight-binding Hamiltonian with\nnearest-neighbor hops. For narrow ribbons we find transmission gaps for both\ntypes of edges. The center of the gap is at the middle of the band in ribbons\nwith armchair edges. This symmetry is due to a property satisfied by the\nmatrices in the resulting linear problem. In ribbons with zigzag edges the gap\ncenter is displaced to the right of the middle of the band. We also find\ntransmission oscillations and resonances within the transmitting region of the\nband for both types of edges. Extending the length of a ribbon does not affect\nthe width of the transmission gap, as long as the ribbon's length is longer\nthan a critical value when the gap can form. Increasing the width of the\nribbon, however, changes the width of the gap. In armchair edges the gap is not\nwell-defined because of the appearance of transmission resonances while in\nzigzag edges the gap width systematically shrinks as the width of the ribbon is\nincreased. We also find only evanescent waves within the gap and both\nevanescent and propagating waves in the transmitting regions."
    },
    {
        "anchor": "Orbital Landau level dependence of the fractional quantum Hall effect in\n  quasi-two dimensional electron layers: finite-thickness effects: The fractional quantum Hall effect (FQHE) in the second orbital Landau level\nat filling factor 5/2 remains enigmatic and motivates our work. We consider the\neffect of the quasi-2D nature of the experimental FQH system on a number of FQH\nstates (fillings 1/3, 1/5, 1/2) in the lowest, second, and third Landau levels\n(LLL, SLL, TLL,) by calculating the overlap, as a function of quasi-2D layer\nthickness, between the exact ground state of a model Hamiltonian and the\nconsensus variational wavefunctions (Laughlin wavefunction for 1/3 and 1/5 and\nthe Moore-Read Pfaffian wavefunction for 1/2). Using large overlap as a\nstability, or FQHE robustness, criterion we find the FQHE does not occur in the\nTLL (for any thickness), is the most robust for zero thickness in the LLL for\n1/3 and 1/5 and for 11/5 in the SLL, and is most robust at finite-thickness\n(4-5 magnetic lengths) in the SLL for the mysterious 5/2 state and the 7/3\nstate. No FQHE is found at 1/2 in the LLL for any thickness. We examine the\norbital effects of an in-plane (parallel) magnetic field finding its\napplication effectively reduces the thickness and could destroy the FQHE at 5/2\nand 7/3, while enhancing it at 11/5 as well as for LLL FQHE states. The\nin-plane field effects could thus be qualitatively different in the LLL and the\nSLL by virtue of magneto-orbital coupling through the finite thickness effect.\nIn the torus geometry, we show the appearance of the threefold topological\ndegeneracy expected for the Pfaffian state which is enhanced by thickness\ncorroborating our findings from overlap calculations. Our results have\nramifications for wavefunction engineering--the possibility of creating an\noptimal experimental system where the 5/2 FQHE state is more likely described\nby the Pfaffian state with applications to topological quantum computing.",
        "positive": "Topological phase transition in wire medium enables high Purcell factor\n  at infrared frequencies: In this paper, we study topological phase transition in a wire medium\noperating at infrared frequencies. This transition occurs in the reciprocal\nspace between the indefinite (open-surface) regime of the metamaterial to its\ndielectric (closed-surface) regime. Due to the spatial dispersion inherent to\nwire medium, a hybrid regime turns out to be possible at the transition\nfrequency. Both such surfaces exist at the same frequency and touch one\nanother. At this frequency, all values of the axial wavevector correspond to\npropagating spatial harmonics. The implication of this regime is the\noverwhelming radiation enhancement. We numerically investigated the gain in\nradiated power for a sub-wavelength dipole source submerged into such the\nmedium. In contrast to all previous works, this gain (called the Purcell\nfactor) turns out to be higher for an axial dipole than for a transversal one."
    },
    {
        "anchor": "Magnetic Ground State of an Individual Fe2+ Ion in Strained\n  Semiconductor Nanostructure: We investigate spin properties of a Fe2+ dopant, known for having single\nnondegenerate ground state in bulk host semiconductor. Due to zero magnetic\nmoment such a ground state is of little use for spintronics and solotronics. We\nshow that this well-established picture of Fe2+ spin configuration can be\ncontradicted by subjecting the Fe2+ ion to sufficiently high strain, e.g.,\nresulting from lattice mismatched epitaxial heterostructures. Our analysis\nreveals that high strain induces qualitative change in the ion energy spectrum\nand results in doubly degenerate ground state with spin projection Sz=+/-2. An\nexperimental proof of this concept is demonstrated using a new system: an\nepitaxial quantum dot containing individual Fe2+ ion. Magnetic character of the\nFe2+ ground state in a CdSe/ZnSe dot is revealed in photoluminescence\nexperiments by exploiting a coupling between a confined exciton and the single\niron impurity.",
        "positive": "Dynamic response of one-dimensional interacting fermions: We evaluate the dynamic structure factor $S(q,\\omega)$ of interacting\none-dimensional spinless fermions with a nonlinear dispersion relation. The\ncombined effect of the nonlinear dispersion and of the interactions leads to\nnew universal features of $S(q,\\omega)$. The sharp peak $S\\propto\nq\\delta(\\omega-uq)$, characteristic for the Tomonaga-Luttinger model, broadens\nup; $S(q,\\omega)$ for a fixed $q$ becomes finite at arbitrarily large $\\omega$.\nThe main spectral weight, however, is confined to a narrow frequency interval\nof the width $\\delta\\omega\\sim q^2/m$. At the boundaries of this interval the\nstructure factor exhibits power-law singularities with exponents depending on\nthe interaction strength and on the wave number $q$."
    },
    {
        "anchor": "Geometric phases of scattering states in a ring geometry: adiabatic\n  pumping in mesoscopic devices: Geometric phases of scattering states in a ring geometry are studied based on\na variant of the adiabatic theorem. Three time scales, i.e., the adiabatic\nperiod, the system time and the dwell time, associated with adiabatic\nscattering in a ring geometry plays a crucial role in determining geometric\nphases, in contrast to only two time scales, i.e., the adiabatic period and the\ndwell time, in an open system. We derive a formula connecting the gauge\ninvariant geometric phases acquired by time-reversed scattering states and the\ncirculating (pumping) current. A numerical calculation shows that the effect of\nthe geometric phases is observable in a nanoscale electronic device.",
        "positive": "Radio-Frequency Rectification on Membrane Bound Pores: We present measurements on direct radio-frequency pumping of ion channels and\npores bound in bilipid membranes. We make use of newly developed microcoaxes,\nwhich allow delivering the high frequency signal in close proximity to the\nmembrane bound proteins and ion channels. We find rectification of the\nradio-frequency signal, which is used to pump ions through the channels and\npores."
    },
    {
        "anchor": "Detection of paramagnetic spins with an ultrathin van der Waals quantum\n  sensor: Detecting magnetic noise from small quantities of paramagnetic spins is a\npowerful capability for chemical, biochemical, and medical analysis. Quantum\nsensors based on optically addressable spin defects in bulk semiconductors are\ntypically employed for such purposes, but the 3D crystal structure of the\nsensor inhibits the sensitivity by limiting the proximity of the defects to the\ntarget spins. Here we demonstrate the detection of paramagnetic spins using\nspin defects hosted in hexagonal boron nitride (hBN), a van der Waals material\nwhich can be exfoliated into the 2D regime. We first create negatively charged\nboron vacancy (V$_{\\rm B}^-$) defects in a powder of ultrathin hBN nanoflakes\n($<10$~atomic monolayers thick on average) and measure the longitudinal spin\nrelaxation time ($T_1$) of this system. We then decorate the dry hBN nanopowder\nwith paramagnetic Gd$^{3+}$ ions and observe a clear $T_1$ quenching, under\nambient conditions, consistent with the added magnetic noise. Finally, we\ndemonstrate the possibility of performing spin measurements including $T_1$\nrelaxometry using solution-suspended hBN nanopowder. Our results highlight the\npotential and versatility of the hBN quantum sensor for a range of sensing\napplications, and pave the way towards the realisation of a truly 2D,\nultrasensitive quantum sensor.",
        "positive": "Transient vortex dynamics and evolution of Bose metal from a 2D\n  superconductor on MoS$_2$: The true character of physical phenomena is thought to be reinforced as the\nsystem becomes disorder-free. In contrast, the two-dimensional (2D)\nsuperconductor is predicted to turn fragile and resistive away from the limit I\n-> 0, B -> 0, in the pinning-free regime. It is intriguing to note that the\nvery vortices responsible for achieving superconductivity by pairing,\ncondensation, and, thereby reducing the classical dissipation, render the state\nresistive driven by quantum fluctuations in the T -> 0. While cleaner systems\nare being explored for technological improvements, the 2D superconductor\nturning resistive when influenced by weak electric and magnetic fields has\nprofound consequences for quantum technologies. A metallic ground state in 2D\nis beyond the consensus of both Bosonic and Fermionic systems, and its origin\nand nature warrant a comprehensive theoretical understanding supplemented by\nin-depth experiments. A real-time observation of the influence of vortex\ndynamics on transport properties so far has been elusive. We explore the nature\nand fate of a low-viscous, clean, 2D superconducting state formed on an\nionic-liquid gated few-layered MoS$_2$ sample. The vortex-core being\ndissipative, the elastic depinning, intervortex interaction, and the subsequent\ndynamics of the vortex-lattice cause the system to behave like an overdamped\nharmonic oscillator, leaving transient signatures in the transport\ncharacteristics. The temperature and magnetic field dependence of the transient\nnature and the noise characteristics of the magnetoresistance confirm that\nquantum fluctuations are solely responsible for the Bose metal state and the\nfragility of the superconducting state."
    },
    {
        "anchor": "Enhancement of sudden death of entanglement for driven qubits: We study the recently discovered phenomena of sudden death of entanglement\nfor a system of two qubits, each of them independently longitudinally damped by\na reservoir and subjected to a continuous driving. We show that driving\nproduces, in the interaction picture, an effective bath that has elements\namounting to various extra sources of noise (transverse, thermal squeezed,\nthermal longitudinal). As a result, the time of sudden death decreases due to\ndriving, which we verify as well by direct numerical calculation. We suggest\nthat this phenomenon can be studied systematically using superconducting qubits\ndriven by microwave fields.",
        "positive": "Origin and Large Enhancement of Large Spin Hall Angle in Weyl Semimetals\n  LaAl$X$ ($X$=Si, Ge): We study the origin of the strong spin Hall effect (SHE) in a recently\ndiscovered family of Weyl semimetals, LaAl$X$ ($X$=Si, Ge) via a\nfirst-principles approach with maximally localized Wannier functions. We show\nthat the strong intrinsic SHE in LaAl$X$ originates from the multiple slight\nanticrossings of nodal lines and points near $E_F$ due to their high mirror\nsymmetry and large spin-orbit interaction. It is further found that both\nelectrical and thermal means can enhance the spin Hall conductivity\n($\\sigma_{SH}$). However, the former also increases the electrical conductivity\n($\\sigma_{c}$), while the latter decreases it. As a result, the independent\ntuning of $\\sigma_{SH}$ and $\\sigma_{c}$ by thermal means can enhance the spin\nHall angle (proportional to $\\frac{\\sigma_{SH}}{\\sigma_{c}}$), a figure of\nmerit of charge-to-spin current interconversion of spin-orbit torque devices.\nThe underlying physics of such independent changes of the spin Hall and\nelectrical conductivity by thermal means is revealed through the band-resolved\nand $k$-resolved spin Berry curvature. Our finding offers a new way in the\nsearch of high SHA materials for room-temperature spin-orbitronics\napplications."
    },
    {
        "anchor": "Atomic force microscopy calibration of standing surface acoustic wave\n  amplitudes: Atomic force microscopy is an important tool for characterizing surface\nacoustic waves, in particular for high frequencies, where the wavelength is too\nshort to be resolved by laser interferometry. A caveat is, that the cantilever\ndeflection is not equal to the amplitude of the surface acoustic wave. We show,\nthat the energy transfer from the moving surface to the cantilever instead\nleads to a deflection exceeding the surface modulation. We present a method for\nan accurate calibration of surface acoustic wave amplitudes based on comparing\nforce-curve measurements with the equation of motion of a driven cantilever. We\ndemonstrate our method for a standing surface acoustic wave on a GaAs crystal\nconfined in a focusing cavity with a resonance frequency near 3 GHz.",
        "positive": "Topological magnetotorsional effect in Weyl semimetals: In this work we introduce a thermal magnetotorsional effect (TME) as a novel\ntopological response in magnetic Weyl semimetals. We predict that magnetization\ngradients perpendicular to the Weyl node separation give rise to temperature\ngradients depending only on the local positions of the Weyl nodes. The TME is a\nconsequence of magnetization-induced effective torsional spacetime geometry and\nthe finite temperature Nieh-Yan anomaly. Similarly to anomalous Hall effect and\nchiral anomaly, the TME has a universal material-independent form. We predict\nthat the TME can be observed in magnetic Weyl semimetal EuCd$_2$As$_2$."
    },
    {
        "anchor": "Strain and field modulation in bilayer graphene band structure: Using an external electric field, one can modulate the bandgap of Bernal\nstacked bilayer graphene by breaking A-~B symmetry. We analyze strain effects\non the bilayer graphene using the extended Huckel theory and find that reduced\ninterlayer distance results in higher bandgap modulation, as expected.\nFurthermore, above about 2.5 angstrom interlayer distance, the bandgap is\ndirect, follows a convex relation to electric field and saturates to a value\ndetermined by the interlayer distance. However, below about 2.5 angstrom, the\nbandgap is indirect, the trend becomes concave and a threshold electric field\nis observed, which also depends on the stacking distance.",
        "positive": "Magnetooptical Properties of Rydberg Excitons - Center-of-Mass\n  Quantization Approach: We show how to compute the magnetooptical functions (absorption, reflection,\nand transmission) when Rydberg Exciton-Polaritons appear, including the effect\nof the coherence between the electron-hole pair and the electromagnetic field,\nand the polaritonic effect. Using the Real Density Matrix Approach the\nanalytical expressions for magnetooptical functions are obtained and numerical\ncalculations for Cu$_2$0 crystal are performed. The influence of the strength\nof applied external magnetic field on the resonance displacement of excitonic\nspectra is discussed. We report a good agreement with recently published\nexperimental data."
    },
    {
        "anchor": "Coupled superconducting spin qubits with spin-orbit interaction: Superconducting spin qubits, also known as Andreev spin qubits, promise to\ncombine the benefits of superconducting qubits and spin qubits defined in\nquantum dots. While most approaches to control these qubits rely on controlling\nthe spin degree of freedom via the supercurrent, superconducting spin qubits\ncan also be coupled to each other via the superconductor to implement two-qubit\nquantum gates. We theoretically investigate the interaction between\nsuperconducting spin qubits in the weak tunneling regime and concentrate on the\neffect of spin-orbit interaction (SOI), which can be large in\nsemiconductor-based quantum dots and thereby offers an additional tuning\nparameter for quantum gates. We find analytically that the effective\ninteraction between two superconducting spin qubits consists of Ising,\nHeisenberg, and Dzyaloshinskii-Moriya interactions and can be tuned by the\nsuperconducting phase difference, the tunnel barrier strength, or the SOI\nparameters. The Josephson current becomes dependent on SOI and spin\norientations. We demonstrate that this interaction can be used for fast\ncontrolled phase-flip gates with a fidelity >99.99%. We propose a scalable\nnetwork of superconducting spin qubits which is suitable for implementing the\nsurface code.",
        "positive": "Effects of spatial dimensionality and band tilting on the longitudinal\n  optical conductivities in Dirac bands: We report a unified theory based on linear response, for analyzing the\nlongitudinal optical conductivity (LOC) of materials with tilted Dirac cones.\nDepending on the tilt parameter $t$, the Dirac electrons have four phases:\nuntilted, type-I, type-II, and type-III; the Dirac dispersion can be isotropic\nor anisotropic; the spatial dimension of the material can be one-, two-, or\nthree-dimensions (1D, 2D and 3D). The interband LOCs and intraband LOCs in $d$\ndimension (with $d\\ge2$) are found to scale as $\\sigma_{0}\\omega^{d-2}$ and\n$\\sigma_{0}\\mu^{d-1}\\delta(\\omega)$, respectively, where $\\omega$ is the\nfrequency and $\\mu$ the chemical potential. The interband LOC vanishes in 1D\ndue to lack of extra spatial dimension. In contrast, the interband LOCs in 2D\nand 3D are nonvanishing and share many similar properties. A universal and\nrobust fixed point of interband LOCs appears at $\\omega=2\\mu$ no matter $d=2$\nor $d=3$, which can be intuitively understood by the geometric structures of\nFermi surface and energy resonance contour. The intraband LOCs and the carrier\ndensity for 2D and 3D tilted Dirac bands are both closely related to the\ngeometric structure of Fermi surface and the cutoff of integration. The angular\ndependence of LOCs is found to characterize both spatial dimensionality and\nband tilting and the constant asymptotic background values of LOC reflect\nfeatures of Dirac bands. The LOCs in the anisotropic tilted Dirac cone can be\nconnected to its isotropic counterpart by a ratio that consists of Fermi\nvelocities for both 2D and 3D. Most of the findings are universal for tilted\nDirac materials and hence valid for a great many Dirac materials in the spatial\ndimensions of physical interest."
    },
    {
        "anchor": "Enhancement of spin-orbit coupling and magnetic scattering in\n  hydrogenated graphene: Spin-orbit coupling (SOC) can provide essential tools to manipulate electron\nspins in two-dimensional materials like graphene, which is of great interest\nfor both fundamental physics and spintronics application. In this paper, we\nreport the low-field magnetotransport of in situ hydrogenated graphene where\nhydrogen atoms are attached to the graphene surface in continuous low\ntemperature and vacuum environment. Transition from weak localization to weak\nantilocalization with increasing hydrogen adatom density is observed,\nindicating enhancing Bychkov-Rashba-type SOC in a mirror symmetry broken\nsystem. From the low-temperature saturation of phase breaking scattering rate,\nthe existence of spin-flip scattering is identified, which corroborates the\nexistence of magnetic moments in hydrogenated graphene.",
        "positive": "Magnetization pinning in modulated nanowires: from topological\n  protection to the \"corkscrew\" mechanism: Diameter-modulated nanowires offer an important paradigm to design the\nmagnetization response of 3D magnetic nanostructures by engineering the domain\nwall pinning. With the aim to understand its nature and to control the process,\nwe analyze the magnetization response in FeCo modulated polycrystalline\ntwo-segment nanowires varying the minor diameter. Our modelling indicates a\nvery complex behavior with a strong dependence on the disorder distribution and\nan important role of topologically non-trivial magnetization structures. We\ndemonstrate that modulated nanowires with a small diameter difference are\ncharacterized by an increased coercive field in comparison to the straight ones\nwhich is explained by a formation of topologically protected walls formed by\ntwo 3D skyrmions with opposite chiralities. For a large diameter difference we\nreport the occurrence of a novel pinning type called here the \"corkscrew\": the\nmagnetization of the large diameter segment forms a skyrmion tube with a core\nposition in a helical modulation along the nanowire. This structure is pinned\nat the constriction and in order to penetrate the narrow segments the\nvortex/skyrmion core size should be reduced."
    },
    {
        "anchor": "Shot Noise of Mesoscopic NS Structures: The Role of Andreev Reflection: Electronic properties of mesoscopic systems made of normal metal in contact\nwith normal and superconducting reservoirs are determined by Andreev\nReflection. We address both experimentally and theoretically how Andreev\nReflection manifests itself in shot noise experiments and what physics can be\ndeduced from such measurements. We report high frequency measurements in which\nAndreev Reflection affects the distribution statistics of the electronic\nexcitations, resulting in a shift of the classical-to-quantum regime or\nequilibrium-to-shot noise crossovers. We also demonstrate that the effective\ncharge carried by paired electrons contains more information: its deviation\nfrom 2e is related to correlations among pairs. This is exemplified by the\nmeasurement of phase dependent noise in an Andreev Interferometer. The use of\nfull counting statistics allows us to understand how the correlations occur,\nand its application to the case of the Andreev Interferometer exhibits a very\ngood agreement between theory and experiment.",
        "positive": "Visualizing Orbital Content of Electronic Bands in Anisotropic 2D\n  Semiconducting ReSe$_{2}$: Many properties of layered materials change as they are thinned from their\nbulk forms down to single layers, with examples including indirect-to-direct\nband gap transition in 2H semiconducting transition metal dichalcogenides as\nwell as thickness-dependent changes in the valence band structure in\npost-transition metal monochalcogenides and black phosphorus. Here, we use\nangle-resolved photoemission spectroscopy to study the electronic band\nstructure of monolayer ReSe$_{2}$, a semiconductor with a distorted 1T\nstructure and in-plane anisotropy. By changing the polarization of incoming\nphotons, we demonstrate that for ReSe$_{2}$, in contrast to the 2H materials,\nthe out-of-plane transition metal $d_{z^{2}}$ and chalcogen $p_{z}$ orbitals do\nnot contribute significantly to the top of the valence band which explains the\nreported weak changes in the electronic structure of this compound as a\nfunction of layer number. We estimate a band gap of 1.7 eV in pristine\nReSe$_{2}$ using scanning tunneling spectroscopy and explore the implications\non the gap following surface-doping with potassium. A lower bound of 1.4 eV is\nestimated for the gap in the fully doped case, suggesting that doping-dependent\nmany-body effects significantly affect the electronic properties of ReSe$_{2}$.\nOur results, supported by density functional theory calculations, provide\ninsight into the mechanisms behind polarization-dependent optical properties of\nrhenium dichalcogenides and highlight their place amongst two-dimensional\ncrystals."
    },
    {
        "anchor": "Keldysh and Doi-Peliti Techniques for out-of-Equilibrium Systems: Lecture notes presented at Windsor NATO school on \"Field Theory of Strongly\nCorrelated Fermions and Bosons in Low-Dimensional Disordered Systems\" (August\n2001). The purpose of these lectures is to give a brief modern introduction to\nKeldysh non-equilibrium field theory and its classical analog - Doi-Peliti\ntechnique. The special emphasis is put on stressing the analogy between the two\napproaches.",
        "positive": "Shot noise generated by graphene p-n junctions in the quantum Hall\n  effect regime: Owing to a linear and gapless band structure and a tunability of the charge\ncarrier type, graphene offers a unique system to investigate transport of Dirac\nFermions at p-n junctions (PNJs). In a magnetic field, combination of quantum\nHall physics and the characteristic transport across PNJs leads to a\nfractionally quantized conductance associated with the mixing of electron-like\nand hole-like modes and their subsequent partitioning. The mixing and\npartitioning suggest that a PNJ could be used as an electronic beam-splitter.\nHere we report the shot noise study of the mode mixing process and demonstrate\nthe crucial role of the PNJ length. For short PNJs, the amplitude of the noise\nis consistent with an electronic beam-splitter behavior, whereas, for longer\nPNJs, it is reduced by the energy relaxation. Remarkably, the relaxation length\nis much larger than typical size of mesoscopic devices, encouraging using\ngraphene for electron quantum optics and quantum information processing."
    },
    {
        "anchor": "Design of Black Phosphorus 2D Nanomechanical Resonators by Exploiting\n  the Intrinsic Mechanical Anisotropy: Black phosphorus (P), a layered material that can be isolated down to\nindividual 2D crystalline sheets, exhibits highly anisotropic mechanical\nproperties due to its corrugated crystal structure in each atomic layer, which\nare intriguing for 2D nanomechanical devices. Here we lay the framework for\ndescribing the mechanical resonant responses in free-standing black P\nstructures, by using a combination of analytical modeling and numerical\nsimulation. We find that thicker devices (>100nm) operating in the elastic\nplate regime exhibit pronounced signatures of mechanical anisotropy, and can\nlead to new multimode resonant characteristics in terms of mode sequences,\nshapes, and orientational preferences that are unavailable in nanomechanical\nresonators made of isotropic materials. In addition, through investigating\ndevices with different geometries, we identify the resonant response's\ndependence on crystal orientation in asymmetric devices, and evaluate the\neffects from the degree of anisotropy. The results suggest a pathway towards\nharnessing the mechanical anisotropy in black P for building novel 2D\nnanomechanical devices and resonant transducers with engineerable multimode\nfunctions.",
        "positive": "Probing topological superconductors with emergent gravity: Topological superconductors are characterized by topological invariants that\ndescribe the number and nature of their robust boundary modes. These invariants\nmust also have observable consequences in the bulk of the system, akin to the\nquantized bulk Hall conductivity in the quantum Hall effect, but such\nconsequences are made elusive by the spontaneous breaking of $U(1)$ symmetry in\nthe superconductor. Here we focus on 2+1 dimensional spin-less $p$-wave\nsuperconductors and show that emergent gravity serves as a natural bulk probe\nfor their topological invariant. This emergent gravity is due to the same\nattractive interaction between fermions that leads to superconductivity, and is\ntherefore built into topological superconductors. The bulk response of a\ntopological superconductor to the emergent gravitational field is encoded in a\ngravitational Chern-Simons term, and is related to the existence of robust\nboundary modes via energy-momentum conservation, or gravitational anomaly\ninflow. The gravitational Chern-Simons term implies a universal relation\nbetween variations in the superconducting order parameter and the\nenergy-momentum currents and densities that they induce. The spontaneous\nbreaking of $U(1)$ symmetry in the superconductor leads to additional bulk\nresponses, encoded in a gravitational pseudo Chern-Simons term. Although not of\ntopological nature, these carry surprising similarities to the topological\nresponses of the gravitational Chern- Simons term. We show how these two types\nof responses can be disentangled."
    },
    {
        "anchor": "GaAs/GaP quantum dots: Ensemble of direct and indirect heterostructures\n  with room temperature optical emission: We describe the optical emission and the carrier dynamics of an ensemble of\nself-assembled GaAs quantum dots embedded in GaP(001). The QD formation is\ndriven by the 3.6 % lattice mismatch between GaAs and GaP in Stranski-Krastanow\nmode after deposition of more than 1.2 monolayers of GaAs. The quantum dots\nhave an areal density between 6 and 7.6x1010 per cm-2 and multimodal size\ndistribution. The luminescence spectra show two peaks in the range of 1.7 and\n2.1 eV. The samples with larger quantum dots have red emission and show less\nthermal quenching compared to the samples with smaller QDs. The large QDs\nluminescence up to room temperature. We attribute the high energy emission to\nindirect carrier recombination in the thin quantum wells or small strained\nquantum dots, whereas the low energy red emission is due to the direct\nelectron-hole recombination in the relaxed quantum dots.",
        "positive": "Metal adsorbate interactions and the convergence of density functional\n  calculations: The adsorption of metal atoms on nanostructures, such as graphene and\nnanotubes, plays an important role in catalysis, electronic doping, and tuning\nmaterial properties. Quantum chemical calculations permit the investigation of\nthis process to discover desirable interactions and obtain mechanistic insights\ninto adsorbate behavior, of which the binding strength is a central quantity.\nHowever, binding strengths vary widely in the literature, even when using\nalmost identical computational methods. To address this issue, we investigate\nthe adsorption of a variety of metals onto graphene, carbon nanotubes, and\nboron nitride nanotubes. As is well-known, calculations on periodic structures\nrequire a sufficiently large system size to remove interactions between\nperiodic images. Our results indicate that there are both direct and indirect\nmechanisms for this interaction, where the latter can require even larger\nsystem sizes than typically employed. The magnitude and distance of the effect\ndepend on the electronic state of the substrate and the open- or closed-shell\nnature of the adsorbate. For instance, insulating substrates (e.g., boron\nnitride nanotubes) show essentially no dependence on system size, whereas\nmetallic or semi-metallic systems can have a substantial effect due to the\ndelocalized nature of the electronic states interacting with the adsorbate. We\nderive a scaling relation for the length dependence with a representative\ntight-binding model. These results demonstrate how to extrapolate the binding\nenergies to the isolated-impurity limit."
    },
    {
        "anchor": "Phase Diagram of a Non-Hermitian Chern Insulator: Destabilization of\n  Chiral Edge States and Bulk-Boundary Correspondence: A non-Hermitian Chern insulator with gain/loss-type non-Hermiticity shows a\npeculiar gap closing; when a nontrivial Chern insulator phase changes to a\ngapless phase, conduction and valence bands are combined into one band owing to\ndestabilization of chiral edge states. A previous recipe of non-Hermitian\nbulk-boundary correspondence is insufficient for this system since such a gap\nclosing is beyond its scope. Here, we revise the recipe by taking the peculiar\ngap closing into account and apply it to the non-Hermitian Chern insulator. We\ndemonstrate that the bulk-boundary correspondence holds in the system including\na destabilization of chiral edge states. A phase diagram derived from the\nbulk-boundary correspondence is shown to be consistent with spectra of the\nsystem.",
        "positive": "Spinful topological phases in acoustic crystals with projective PT\n  symmetry: For the classification of topological phases of matter, an important\nconsideration is whether a system is spinless or spinful, as these two classes\nhave distinct symmetry algebra that gives rise to fundamentally different\ntopological phases. However, only recently has it been realized theoretically\nthat in the presence of gauge symmetry, the algebraic structure of symmetries\ncan be projectively represented, which possibly enables the switch between\nspinless and spinful topological phases. Here, we report the first experimental\ndemonstration of this idea by realizing spinful topological phases in\n\"spinless\" acoustic crystals with projective space-time inversion symmetry. In\nparticular, we realize a DIII-class one-dimensional topologically gapped phase\ncharacterized by a 2Z winding number, which features Kramers degenerate bands\nand Kramers pair of topological boundary modes. Our work thus overcomes a\nfundamental constraint on topological phases by spin classes."
    },
    {
        "anchor": "All-Electrical Skyrmionic Bits in a Chiral Magnetic Tunnel Junction: Topological spin textures such as magnetic skyrmions hold considerable\npromise as robust, nanometre-scale, mobile bits for sustainable computing. A\nlongstanding roadblock to unleashing their potential is the absence of a device\nenabling deterministic electrical readout of individual spin textures. Here we\npresent the wafer-scale realization of a nanoscale chiral magnetic tunnel\njunction (MTJ) hosting a single, ambient skyrmion. Using a suite of electrical\nand multi-modal imaging techniques, we show that the MTJ nucleates skyrmions of\nfixed polarity, whose large readout signal - 20-70% relative to uniform states\n- corresponds directly to skyrmion size. Further, the MTJ exploits\ncomplementary mechanisms to stabilize distinctly sized skyrmions at zero field,\nthereby realizing three nonvolatile electrical states. Crucially, it can write\nand delete skyrmions using current densities 1,000 times lower than\nstate-of-the-art. These results provide a platform to incorporate readout and\nmanipulation of skyrmionic bits across myriad device architectures, and a\nspringboard to harness chiral spin textures for multi-bit memory and\nunconventional computing.",
        "positive": "Steady state theory of current transfer: Current transfer is defined as a charge transfer process where the\ntransferred charge carries information about its original motion. We have\nrecently suggested that such transfer causes the asymmetry observed in electron\ntransfer induced by circularly polarized light through helical wires. This\npaper presents the steady state theory of current transfer within a tight\nbinding model of coupled wires systems. The efficiency of current transfer is\nquantified in terms of the calculated asymmetry in the system response to a\nsteady current imposed on one of the wires, with respect to the imposed current\ndirection."
    },
    {
        "anchor": "EDEPR of impurity centers embedded in silicon microcavities: We present the first findings of the new electrically-detected EPR (EDEPR)\ntechnique which reveal different shallow and deep centers without using the\nexternal cavity as well as the hf source and recorder, with measuring the only\nmagnetoresistance of the Si-QW confined by the superconductor delta-barriers.",
        "positive": "A Variational Approach to Extracting the Phonon Mean Free Path\n  Distribution from the Spectral Boltzmann Transport Equation: The phonon Boltzmann transport equation (BTE) is a powerful tool for studying\nnon-diffusive thermal transport. Here, we develop a new universal variational\napproach to solving the BTE that enables extraction of phonon mean free path\n(MFP) distributions from experiments exploring non-diffusive transport. By\nutilizing the known Fourier solution as a trial function, we present a direct\napproach to calculating the effective thermal conductivity from the BTE. We\ndemonstrate this technique on the transient thermal grating (TTG) experiment,\nwhich is a useful tool for studying non-diffusive thermal transport and probing\nthe mean free path (MFP) distribution of materials. We obtain a closed form\nexpression for a suppression function that is materials dependent, successfully\naddressing the non-universality of the suppression function used in the past,\nwhile providing a general approach to studying thermal properties in the\nnon-diffusive regime."
    },
    {
        "anchor": "Non-Equilibrated Counter Propagating Edge Modes in the Fractional\n  Quantum Hall Regime: It is well established that 'density reconstruction' at the edge of a two\ndimensional electron gas takes place for 'hole-conjugate' states in the\nfractional quantum Hall effect (such as ${\\nu}=2/3, 3/5,$ etc.). Such\nreconstruction leads, after equilibration between counter propagating edge\nchannels, to a downstream chiral current edge mode accompanied by upstream\nchiral neutral modes (carrying energy without net charge). Short equilibration\nlength prevented thus far observation of the counter propagating current\nchannels - the hallmark of density reconstruction. Here, we provide evidence\nfor such non-equilibrated counter-propagating current channels, in short\nregions $(l=4{\\mu}m$ and $l=0.4{\\mu}m)$ of fractional filling ${\\nu}=2/3$, and,\nunexpectedly, ${\\nu}=1/3$, sandwiched between two regions of integer filling\n${\\nu}=1$. Rather than a two-terminal fractional conductance, the conductance\nexhibited a significant ascension towards unity quantum conductance\n$(G_Q=e^2/h)$ at or near the fractional plateaus. We attribute this conductance\nrise to the presence of a non-equilibrated downstream ${\\nu}=1$ channel in the\nfractional short regions.",
        "positive": "Diffusion and drift of graphene flake on graphite surface: Diffusion and drift of a graphene flake on a graphite surface are analyzed. A\npotential energy relief of the graphene flake is computed using ab initio and\nempirical calculations. Based on the analysis of this relief, different\nmechanisms of diffusion and drift of the graphene flake on the graphite surface\nare considered. A new mechanism of diffusion and drift of the flake is\nproposed. According to the proposed mechanism, rotational transition of the\nflake from commensurate to incommensurate state takes place with subsequent\nsimultaneous rotation and translational motion until a commensurate state is\nreached again, and so on. Analytic expressions for the diffusion coefficient\nand mobility of the flake corresponding to different mechanisms are derived in\nwide ranges of temperatures and sizes of the flake. The molecular dynamics\nsimulations and estimates based on ab initio and empirical calculations\ndemonstrate that the proposed mechanism can be dominant under certain\nconditions. The influence of structural defects on the diffusion of the flake\nis examined on the basis of calculations of the potential energy relief and\nmolecular dynamics simulations. The methods of control over the diffusion and\ndrift of graphene components in nanoelectromechanical systems are discussed.\nThe possibility to experimentally determine the barriers to relative motion of\ngraphene layers based on the study of diffusion of a graphene flake is\nconsidered. The results obtained can be also applied to polycyclic aromatic\nmolecules on graphene and should be qualitatively valid for a set of\ncommensurate adsorbate-adsorbent systems."
    },
    {
        "anchor": "Spectroscopy Study on NV Sensors in Diamond-based High-pressure Devices: Recently, the negatively charged nitrogen-vacancy (NV) center has emerged as\na robust and versatile quantum sensor in pressurized environments. There are\ntwo popular ways to implement NV sensing in a diamond anvil cell (DAC), which\nis a conventional workhorse in the high-pressure community: create implanted NV\ncenters (INVs) at the diamond anvil tip or immerse NV-enriched nano-diamonds\n(NDs) in the pressure medium. Nonetheless, there are limited studies on\ncomparing the local stress environments experienced by these sensor types as\nwell as their performances as pressure gauges. In this work, by probing the NV\nenergy levels with the optically detected magnetic resonance (ODMR) method, we\nexperimentally reveal a dramatic difference in the partially reconstructed\nstress tensors of INVs and NDs incorporated in the same DAC. Our measurement\nresults agree with computational simulations, concluding that INVs perceive a\nmore non-hydrostatic environment dominated by a uniaxial stress along the DAC\naxis. This provides insights on the suitable choice of NV sensors for specific\npurposes and the stress distribution in a DAC. We further propose some possible\nmethods, such as using NDs and nanopillars, to extend the maximum working\npressure of quantum sensing based on ODMR spectroscopy, since the maximum\nworking pressure could be restricted by non-hydrostaticity of the pressure\nenvironment. Moreover, we explore more sensing applications of the NV center by\nstudying how pressure modifies different aspects of the NV system. We perform a\nphotoluminescence study using both INVs and NDs to determine the pressure\ndependence of the zero-phonon line, which helps developing an all-optical\npressure sensing protocol with the NV center. We also characterize the\nspin-lattice relaxation ($T_1$) time of INVs under pressure to lay a foundation\nfor robust pulsed measurements with NV centers in pressurized environments.",
        "positive": "Hydrodynamic approach to two-dimensional electron systems: The last few years have seen an explosion of interest in hydrodynamic effects\nin interacting electron systems in ultra-pure materials. One such material,\ngraphene, is not only an excellent platform for the experimental realization of\nthe hydrodynamic flow of electrons, but also allows for a controlled derivation\nof the hydrodynamic equations on the basis of kinetic theory. The resulting\nhydrodynamic theory of electronic transport in graphene yields quantitative\npredictions for experimentally relevant quantities, e.g. viscosity, electrical\nconductivity, etc. Here I review recent theoretical advances in the field,\ncompare the hydrodynamic theory of charge carriers in graphene with\nrelativistic hydrodynamics and recent experiments, and discuss applications of\nhydrodynamic approach to novel materials beyond graphene."
    },
    {
        "anchor": "Direct current control of three magnon scattering processes in\n  spin-valve nanocontacts: We have investigated the generation of spin waves in the free layer of an\nextended spin-valve structure with a nano-scaled point contact driven by both\nmicrowave and direct electric current using Brillouin light scattering\nmicroscopy. Simultaneously with the directly excited spin waves, strong\nnonlinear effects are observed, namely the generation of eigenmodes with\ninteger multiple frequencies (2 \\emph{f}, 3 \\emph{f}, 4 \\emph{f}) and modes\nwith non-integer factors (0.5 \\emph{f}, 1.5 \\emph{f}) with respect to the\nexcitation frequency \\emph{f}. The origin of these nonlinear modes is traced\nback to three magnon scattering processes. The direct current influence on the\ngeneration of the fundamental mode at frequency \\emph{f} can be related to the\nspin-transfer torque, while the efficiency of three-magnon-scattering processes\nis controlled by the Oersted field as an additional effect of the direct\ncurrent.",
        "positive": "Cherenkov friction on a neutral particle moving parallel to a dielectric: Based on a fully relativistic framework and the assumption of local\nequilibrium, we describe a simple mechanism of quantum friction for a particle\nmoving parallel to a dielectric. The Cherenkov effect explains how the bare\nground state becomes globally unstable and how fluctuations of the\nelectromagnetic field and the particle's dipole are converted into pairs of\nexcitations. Modelling the particle as a silver nano-sphere, we investigate the\nspectrum of the force and its velocity dependence. We find that the damping of\nthe plasmon resonance in the silver particle has a relatively strong impact\nnear the Cherenkov threshold velocity. We also present an expansion of the\nfriction force near the threshold velocity for both damped and undamped\nparticles."
    },
    {
        "anchor": "Orbital Hall effect in mesoscopic devices: We investigate the orbital Hall effect through a mesoscopic device with\nmomentum-space orbital texture that is connected to four semi-infinite\nterminals embedded in the Landauer-B\\\"uttiker configuration for quantum\ntransport. We present analytical and numerical evidence that the orbital Hall\ncurrent exhibits mesoscopic fluctuations, which can be interpreted in the\nframework of random matrix theory (RMT) (as with spin Hall current\nfluctuations). The mesoscopic fluctuations of orbital Hall current display two\ndifferent amplitudes of 0.36 and 0.18 for weak and strong spin-orbit coupling,\nrespectively. The amplitudes are obtained by analytical calculation via RMT and\nare supported by numerical calculations based on the tight-binding model.\nFurthermore, the orbital Hall current fluctuations lead to two relationships\nbetween the orbital Hall angle and conductivity. Finally, we confront the two\nrelations with experimental data of the orbital Hall angle, which shows good\nconcordance between theory and experiment.",
        "positive": "Unveiling Real Triple Degeneracies in Crystals: Exploring Link and\n  Compound Structures: With their non-Abelian topological charges, real multi-bandgap systems\nchallenge the conventional topological phase classifications. As the minimal\nsector of multi-bandgap systems, real triple degeneracies (RTPs), which serve\nas real 'Weyl points', lay the foundation for the research on real topological\nphases. However, experimental demonstration of physical systems with global\nband configurations consisting of multiple RTPs in crystals has not been\nreported. Here we present experimental evidence of RTPs in photonic\nmeta-crystals, characterizing them using the Euler number, and establishing\ntheir connection with both Abelian and non-Abelian charges. By considering RTPs\nas the basic elements, we further propose the concept of a topological\ncompound, akin to a chemical compound, where we find that certain phases are\nnot topologically allowed. The topological classification of RTPs in crystals\ndemonstrated in our work plays a similar role as the 'no-go' theorem in Weyl\nsystems."
    },
    {
        "anchor": "Mechanism of current-assisted Bloch-point wall stabilization for ultra\n  fast dynamics: Two types of domain walls exist in magnetically soft cylindrical nanowires:\nthe transverse-vortex wall (TVW) and the Bloch-point wall (BPW). The latter is\nexpected to prevent the usual Walker breakdown, and thus enable high domain\nwall speed. We showed recently [M. Sch\\\"obitz \\etal, Phys. Rev. Lett. 123,\n217201 (2019)] that the previously overlooked OErsted field associated with an\nelectric current is a key in experiments to stabilize the BPW and reach speed\nabove 600 m/s with spin-transfer. Here, we investigate in detail this situation\nwith micromagnetic simulations and modeling. The switching of the azimuthal\ncirculation of the BPW to match that of the OErsted field occurs above a\nthreshold current scaling with $1/R^3$ ($R$ is the wire radius), through\nmechanisms that may involve the nucleation and/or annihilation of Bloch points.\nThe domain wall dynamics then remains of a below-Walker type, with speed\nlargely determined by spin-transfer torque alone.",
        "positive": "Voltage-control of damping constant in\n  magnetic-insulator/topological-insulator bilayers: The magnetic damping constant is a critical parameter for magnetization\ndynamics and the efficiency of memory devices and magnon transport. Therefore,\nits manipulation by electric fields is crucial in spintronics. Here, we\ntheoretically demonstrate the voltage-control of magnetic damping in ferro- and\nferrimagnetic-insulator (FI)/topological-insulator (TI) bilayers. Assuming a\ncapacitor-like setup, we formulate an effective dissipation torque induced by\nspin-charge pumping at the FI/TI interface as a function of an applied voltage.\nBy using realistic material parameters, we find that the effective damping for\na FI with 10nm thickness can be tuned by one order of magnitude under the\nvoltage with 0.25V. Also, we provide perspectives on the voltage-induced\nmodulation of the magnon spin transport on proximity-coupled FIs."
    },
    {
        "anchor": "Joint measurement of current-phase relations and transport properties of\n  hybrid junctions using a three junctions SQUID: We propose a scheme to measure both the current-phase relation and\ndifferential conductance $dI/dV$ of a superconducting junction, in the normal\nand the superconducting states. This is done using a dc Superconducting Quantum\nInterference Device (dc SQUID) with two Josephson junctions in parallel with\nthe device under investigation and three contacts. As a demonstration we\nmeasure the current-phase relation and $dI/dV$ of a small Josephson junction\nand a carbon nanotube junction. In this latter case, in a regime where the\nnanotube is well conducting, we show that the non-sinusoidal current phase\nrelation we find is consistent with the theory for a weak link, using the\ntransmission extracted from the differential conductance in the normal state.\nThis method holds great promise for future investigations of the current-phase\nrelation of more exotic junctions.",
        "positive": "Operation speed of polariton condensate switches gated by excitons: We present a time-resolved photoluminescence (PL) study in real- and\nmomentum-space of a polariton condensate switch in a quasi-1D semiconductor\nmicrocavity. The polariton flow across the ridge is gated by excitons inducing\na barrier potential due to repulsive interactions. A study of the device\noperation dependence on the power of the pulsed gate beam obtains a\nsatisfactory compromise for the ON/OFF-signal ratio and -switching time of the\norder of 0.3 and $\\thicksim50$ ps, respectively. The opposite transition is\ngoverned by the long-lived gate excitons, consequently the OFF/ON-switching\ntime is $\\thicksim200$ ps, limiting the overall operation speed of the device\nto $\\thicksim3$ GHz. The experimental results are compared to numerical\nsimulations based on a generalized Gross-Pitaevskii equation, taking into\naccount incoherent pumping, decay and energy relaxation within the condensate."
    },
    {
        "anchor": "Highly uniform GaSb quantum dots with indirect-direct bandgap crossover\n  at telecom range: We demonstrate a new quantum-confined semiconductor material based on GaSb\nquantum dots (QDs) embedded in single-crystalline AlGaSb matrix by filling\ndroplet-etched nanoholes. The droplet-mediated growth mechanism allows\nformation of low QD densities required for non-classical single-QD light\nsources. The photoluminescence (PL) experiments reveal that the GaSb QDs have\nan indirect-direct bandgap crossover at telecom wavelengths. This is due to the\nalignment of the {\\Gamma} and L valleys in the conduction band as a result of\nquantum confinement controlled by dimensions of the nanostructure. We show that\nin the direct bandgap regime close to 1.5 um wavelength, the GaSb QDs have a\ntype I band alignment and exhibit excitonic emission with narrow spectral lines\nand very low inhomogeneous broadening of PL emission owing to the high material\nquality and dimensional uniformity. These properties are extremely promising in\nterms of applications in infrared quantum optics and quantum photonic\nintegration.",
        "positive": "Enhancement of the spin Hall voltage in a reverse-biased planar\n  pn-junction: We report an experimental demonstration of a local amplification of the spin\nHall voltage using an expanding depletion zone at a pn-junction in GaAs/AlGaAs\nHall-bar microdevices. It is demonstrated that the depletion zone can be\nspatially expanded by applying reverse bias by at least 10~$\\mu$m at low\ntemperature. In the depleted regime, the spin Hall signals reached more than\none order of magnitude higher values than in the normal regime at the same\nelectrical current flowing through the micro-device. It is shown that the\npn-bias has two distinct effects on the detected spin Hall signal. It controls\nthe local drift field at the Hall cross which is highly non-linear in the\npn-bias due to the shift of the depletion front. Simultaneously, it produces a\nchange in the spin-transport parameters due to the non-linear change in the\ncarrier density at the Hall cross with the pn-bias."
    },
    {
        "anchor": "Efficient calculation of inelastic vibration signals in electron\n  transport: Beyond the wide-band approximation: We extend the simple and efficient lowest order expansion (LOE) for inelastic\nelectron tunneling spectroscopy (IETS) to include variations in the electronic\nstructure on the scale of the vibration energies. This enables first-principles\ncalculations of IETS lineshapes for molecular junctions close to resonances and\nband edges. We demonstrate how this is relevant for the interpretation of\nexperimental IETS using both a simple model and atomistic first-principles\nsimulations.",
        "positive": "Ferromagnetic domain wall as a nonreciprocal string: We present a simple model of a domain wall in a thin-film ferromagnet. A\ndomain wall is represented as a nonreciprocal string, on which transverse waves\npropagate with different speeds in opposite directions. The model has three\nparameters: mass density, tension, and a gyroscopic constant quantifying the\nnonreciprocity. We discuss the unusual dynamics of a nonreciprocal string in\nfinite geometry. It agrees well with numerically simulated motion of a\nferromagnetic domain wall in a strip of constant width."
    },
    {
        "anchor": "Edge bands and vertical transport in topological insulator/magnetic\n  insulator heterostructures: The low-energy band-structure of electrons propagating on a lateral surface\nof a heterostructure consisting of three dimensional topological insulator (TI)\nand magnetic insulator layers has been calculated. The energy spectrum is\nhighly tunable depending on the relation between the interlayer tunneling\namplitude, Zeeman energy and surface potential. A ratio between the first two\nparameters controls a topological transition between chiral and helical surface\nstate band-structures. In the former case localized states, whose\nwave-functions are confined near single TI layers, emerge in a narrow parameter\nrange where they coexist with itinerant states. In regular superlattices these\nlocalized states form a flat band in the vertical direction. Such a\nlocalization has a topological origin. It is associated with a specific spatial\nspin texture of these states. The localized states vanish upon the topological\nphase transition from the anomalous quantum Hall regime to a trivial phase\ncharacterized by an anisotropic Dirac cone on the lateral surface of the\nheterostructure.",
        "positive": "A Strongly Correlated Quantum-Dot Heat Engine with Optimal Performance:\n  An Non-equilibrium Green's function Approach: We present an analytical study of a strongly correlated quantum dot-based\nthermoelectric particle-exchange heat engine for both finite and infinite\non-dot Coulomb interaction. Employing Keldysh's non-equilibrium Green's\nfunction formalism for different decoupling schemes in the equation of motion,\nwe have analyzed the thermoelectric properties within the non-linear transport\nregime. As the simplest mean-field approximation is insufficient for analyzing\nthermoelectric properties in the Coulomb blockade regime, one needs to employ a\nhigher-order approximation to study strongly correlated QD-based heat engines.\nTherefore initially, we have used the Hubbard-\\Romannum{1} approximation to\nstudy the quantum dot level position ($\\epsilon_d$), thermal gradient ($\\Delta\nT$), and on-dot Coulomb interaction ($U$) dependence of the thermoelectric\nproperties. Furthermore, as a natural extension, we have used an approximation\nbeyond Hubbard-\\Romannum{1} in the infinite-$U$ limit (strong on-dot Coulomb\nrepulsion) to provide additional insight into the operation of a more practical\nquantum dot heat engine. Within this infinite-$U$ limit, we examine the role of\nthe symmetric dot-reservoir tunneling ($\\Gamma$) and external serial load\nresistance ($R$) in optimizing the performance of the strongly correlated\nquantum dot heat engine. Our infinite-$U$ results show a good quantitative\nagreement with recent experimental data for a quantum dot coupled to two\nmetallic reservoirs."
    },
    {
        "anchor": "Resonance effects in the Raman scattering of mono- and few layers\n  MoSe$_2$: Using resonant Raman scattering spectroscopy with 25 different laser lines,\nwe describe the Raman scattering spectra of mono- and multi-layers\n2H-molybdenum diselenide (MoSe$_2$) as well as the different resonances\naffecting the most pronounced features. For high-energy phonons, both A- and E-\nsymmetry type phonons present resonances with A and B excitons of MoSe$_2$\ntogether with a marked increase of intensity when exciting at higher energy,\nclose to the C exciton energy. We observe symmetry dependent exciton-phonon\ncoupling affecting mainly the low-energy rigid layer phonon modes. The shear\nmode for multilayer displays a pronounced resonance with the C exciton while\nthe breathing mode has an intensity that grows with the excitation laser\nenergy, indicating a resonance with electronic excitations at energies higher\nthan that of the C exciton.",
        "positive": "An In-situ Annealing effect of Graphene-Graphene Interlayer Conduction: An interlayer distance modulation in twisted bilayer graphene is reported.\nThis is achieved by an in-situ annealing technique. The transformation of\nsystematic vacuum and hydrogen annealing effects in twisted bilayer CVD\ngraphene on SiO2 surface is reported based on experimental results. Incoherent\ninterlayer conduction is observed in the twisted bilayer device. In-situ\nannealing efficiently removes the residues in the graphene-to-graphene\ninterface and enhances the interlayer conduction. We demonstrate\ngraphene-to-graphene interlayer resistance modulated by an order of magnetite\nat 5 K. We also report on the behavior of molecular hydrogen on graphene\ninterlayer using the gate voltage-dependent resistance as a function of\ntemperature at atmospheric pressure. It was observed that interlayer conduction\nin hydrogen/argon gas ambient is reduced. Results imply that modulation in the\ninterlayer distance of graphene-to-graphene junction, as determined by the\ntransport measurement investigation. Overall this result leads to the\npossibility of making electrically tunable devices using twisted bilayer\ngraphene."
    },
    {
        "anchor": "Advances toward high-accuracy gigahertz operation of tunable-barrier\n  single-hole pumps in silicon: Precise and reproducible current generation is key to realize quantum current\nstandards in metrology. A promising candidate is a tunable-barrier\nsingle-charge pump, which can accurately transfer single charges one by one\nwith an error rate of less than ppm level. Although several high-accuracy\nmeasurements have revealed such a high performance of the pumps, it is\nnecessary to further pursue the possibility of high-precision operation toward\nreproducible generation of the pumping current in many devices. Here, we\ninvestigate in detail a silicon single-hole pumps, which are potentially\nexpected to have a superior performance to single-electron pumps because of a\nheavy effective mass of holes. Temperature dependence measurements of current\ngenerated by the single-hole pump revealed a high energy selectivity of the\ntunnel barrier, which is a critical parameter to achieve high-accuracy\noperation. In addition, we applied the dynamic gate compensation technique to\nthe single-hole pump and confirm the further performance improvement.\nFurthermore, we demonstrate gigahertz operation of a single-hole pump with an\nestimated lower bound of an error rate of around 0.01 ppm. These results imply\na superior capability of single-hole pumps in silicon toward high-accuracy,\nhigh-speed, and stable single-charge pumping appropriate for not only\nmetrological applications but also quantum device applications.",
        "positive": "Nano-optical imaging of WSe2 waveguide modes revealing light-exciton\n  interactions: We report on nano-optical imaging study of WSe2 thin flakes with the scanning\nnear-field optical microscopy (NSOM). The NSOM technique allows us to visualize\nin real space various waveguide photon modes inside WSe2. By tuning the\nexcitation laser energy, we are able to map the entire dispersion of these\nwaveguide modes both above and below the A exciton energy of WSe2. We found\nthat all the modes interact strongly with WSe2 excitons. The outcome of the\ninteraction is that the observed waveguide modes shift to higher momenta right\nbelow the A exciton energy. At higher energies, on the other hand, these modes\nare strongly damped due to adjacent B excitons or band edge absorptions. The\nmode-shifting phenomena are consistent with polariton formation in WSe2."
    },
    {
        "anchor": "Fracturing graphene by chlorination: a theoretical viewpoint: Motivated by the recent photochlorination experiment [B. Li et al., ACS Nano\n5, 5957 (2011)], we study theoretically the interaction of chlorine with\ngraphene. In previous theoretical studies, covalent binding between chlorine\nand carbon atoms has been elusive upon adsorption to the graphene basal plane.\nInterestingly, in their recent experiment, Li et al. interpreted their data in\nterms of chemical bonding of chlorine on top of the graphene plane, associated\nwith a change from sp2 to sp3 in carbon hybridization and formation of graphene\nnanodomains. We study the hypothesis that these domains are actually fractured\ngraphene with chlorinated edges, and compare the energetics of\nchlorine-containing graphene edge terminations, both in zigzag and armchair\ndirections, to chlorine adsorption onto infinite graphene. Our results indicate\nthat edge chlorination is favored over adsorption in the experimental\nconditions with radical atomic chlorine and that edge chlorination with\nsp3-hybridized edge carbons is stable also in ambient conditions. An ab initio\nthermodynamical analysis shows that the presence of chlorine is able to break\nthe pristine graphene layer. Finally, we discuss the possible effects of the\nsilicon dioxide substrate on the chlorination of graphene.",
        "positive": "Generation and detection of a spin entanglement in nonequilibrium\n  quantum dots: Spin entanglement between two spatially separated electrons can be generated\nin nonequilibrium interacting quantum dots, coherently coupled to a common\nlead. In this system entangled two-electron states develop which are Werner\nstates with an imbalance between singlet and triplet probabilities. We propose\na multi-terminal, multiply-connected setup for the generation and detection of\nthis imbalance. In particular, we identify a regime in which the formation of\nspin entanglement leads to a cancellation of Aharonov-Bohm oscillations."
    },
    {
        "anchor": "Manipulation of the Land$\\acute{\\text{e}}$ g-factor in InAs quantum dots\n  through the application of anisotropic gate potentials: Exact\n  diagonalization, numerical and perturbation methods: We study the variation in the Land$\\acute{\\text{e}}$ g-factor of electron\nspins induced by both anisotropic gate potentials and magnetic fields in InAs\nquantum dots for possible implementation towards solid state quantum computing.\nIn this paper, we present analytical expressions and numerical simulations of\nthe variation in the Land$\\acute{\\text{e}}$ g-factor for both isotropic and\nanisotropic quantum dots. Using both analytical techniques and numerical\nsimulations, we show that the Rashba spin-orbit coupling has a major\ncontribution in the variation of the g-factor with electric fields before the\nregime, where level crossing or anticrossing occurs. In particular, the\nelectric field tunability is shown to cover a wide range of g-factor through\nstrong Rashba spin-orbit interaction. Another major result of this paper is\nthat the anisotropic gate potential gives quenching effect in the orbital\nangular momentum that reduces the variation in the E-field and B-field\ntunability of the g-factor if the area of the symmetric and asymmetric quantum\ndots is held constant. We identify level crossings and anticrossings of the\nelectron states in the variation of the Land$\\acute{\\text{e}}$ g-factor. We\nmodel the wavefunctions of electron spins and estimate the size of the\nanticrossing for the spin states $|0,-1,+1/2>$ and $|0,0,-1/2>$ corresponding\nto a quantum dot that has been recently studied experimentally (Phys. Rev.\nLett. \\textbf{104}, 246801 (2010)).",
        "positive": "Transport properties in gapped graphene through magnetic barrier in a\n  laser field: We study the transport properties of Dirac fermions through gapped graphene\nthrough a magnetic barrier irradiated by a laser field oscillating in time. We\nuse Floquet theory and the solution of Weber's differential equation to\ndetermine the energy spectrum corresponding to the three regions composing the\nsystem. The boundary conditions and the transfer matrix approach {are} employed\nto explicitly determine the transmission probabilities for multi-energy bands\nand the associated conductance. As an illustration, we focus only on the three\nfirst bands: the central band $T_0$ (zero photon exchange) and the two first\nside bands $T_{\\pm1}$ (photon emission or absorption). It is found that the\nlaser field activates the process of translation through photon exchange.\nFurthermore, we show that varying the incident angle and energy gap strongly\naffects the transmission process. The conductance increases when the number of\nelectrons that cross the barrier increases, namely when there is a significant\ntransmission."
    },
    {
        "anchor": "Potential Energy Landscape for hot electrons in periodically\n  nanostructured graphene: We explore the spatial variations of the unoccupied electronic states of\ngraphene epitaxially grown on Ru(0001) and observed three unexpected features:\nthe first graphene image state is split in energy, unlike all other image\nstates, the split state does not follow the local work function modulation, and\na new interfacial state at +3 eV appears on some areas of the surface. These\nresults show the system behaves as a self-organized periodic array of quantum\ndots.",
        "positive": "Topological response in ferromagnets: We present a theory of the intrinsic anomalous Hall effect in a model of a\ndoped Weyl semimetal, which serves here as the simplest toy model of a generic\nthree-dimensional metallic ferromagnet with Weyl nodes in the electronic\nstructure. We analytically evaluate the anomalous Hall conductivity as a\nfunction of doping, which allows us to explicitly separate the Fermi surface\nand non Fermi surface contributions to the Hall conductivity by carefully\nevaluating the zero frequency and zero wavevector limits of the corresponding\nresponse function. We show that this separation agrees with the one suggested a\nlong time ago in the context of the quantum Hall effect by Streda."
    },
    {
        "anchor": "Interaction correction to conductivity of Al$_x$Ga$_{1-x}$As/GaAs double\n  quantum well heterostructures near the balance: The electron-electron interaction quantum correction to the conductivity of\nthe gated double well Al$_x$Ga$_{1-x}$As/GaAs structures is investigated\nexperimentally. The analysis of the temperature and magnetic field dependences\nof the conductivity tensor allows us to obtain reliably the diffusion part of\nthe interaction correction for the regimes when the structure is balanced and\nwhen only one quantum well is occupied. The surprising result is that the\ninteraction correction does not reveal resonant behavior; it is practically the\nsame for both regimes.",
        "positive": "Tracking Surface Charge Dynamics on Single Nanoparticles: Surface charges play a fundamental role in physics and chemistry,\nparticularly in shaping the catalytic properties of nanomaterials. Tracking\nnanoscale surface charge dynamics remains challenging due to the involved\nlength and time scales. Here, we demonstrate real-time access to the nanoscale\ncharge dynamics on dielectric nanoparticles employing reaction nanoscopy. We\npresent a four-dimensional visualization of the non-linear charge dynamics on\nstrong-field irradiated single SiO$_2$ nanoparticles with femtosecond-nanometer\nresolution and reveal how surface charges affect surface molecular bonding with\nquantum dynamical simulations. We performed semi-classical simulations to\nuncover the roles of diffusion and charge loss in the surface charge\nredistribution process. Understanding nanoscale surface charge dynamics and its\ninfluence on chemical bonding on a single nanoparticle level unlocks an\nincreased ability to address global needs in renewable energy and advanced\nhealthcare."
    },
    {
        "anchor": "Temperature Dependence of the Anomalous Hall Effect from Electron\n  Interactions: We consider the impact of electron-electron interactions on the temperature\ndependence of the anomalous Hall effect in disordered conductors. The\nmicroscopic analysis is carried out within the diagrammatic approach of the\nlinear response Kubo-Streda formula with an account of both extrinsic\nskew-scattering and side-jump mechanisms of the anomalous Hall effect arising\nin the presence of spin-orbit coupling. We demonstrate the importance of\nelectron interactions in the Cooper channel even for nominally\nnon-superconducting materials and find that the corresponding low-temperature\ndependence of the anomalous Hall conductivity is asymptotically of the form\n$\\sqrt{T}/\\ln(T_0/T)$ in three dimensions and $\\ln[\\ln(T_0/T)]$ in two\ndimensions, where the scale of $T_0$ is parametrically of the order of Fermi\nenergy. These results, in particular, may provide an explanation for the\nrecently observed unconventional temperature dependence of the anomalous Hall\neffect in HgCr$_2$Se$_4$.",
        "positive": "Connecting the dots: Time-reversal symmetric Weyl Semimetals with\n  tunable Fermi arcs: We propose a one-parameter family of noninteracting lattice models for Weyl\nsemimetals with 4 Weyl nodes and tunable Fermi arcs. These 2-band model\nHamiltonians are time-reversal symmetric with $\\mathrm{T}^2 = + 1$, and tuning\nthe parameter changes the connectivity of the Fermi arcs continuously without\naffecting the location and chiralities of the Weyl nodes in the bulk Brillouin\nzone. The bulk polarization and magnetization are shown to vary with this\nparameter, a dependence inaccessible to the low energy effective field theory."
    },
    {
        "anchor": "Current-induced birefringent absorption and non-reciprocal plasmons in\n  graphene: We present extensive calculations of the optical and plasmonic properties of\na graphene sheet carrying a dc current. By calculating analytically the\ndensity-density response function of current-carrying states at finite\ntemperature, we demonstrate that an applied dc current modifies the Pauli\nblocking mechanism and that absorption acquires a birefringent character with\nrespect to the angle between the in-plane light polarization and current flow.\nEmploying the random phase approximation at finite temperature, we show that\ngraphene plasmons display a degree of non-reciprocity and collimation that can\nbe tuned with the applied current. We discuss the possibility to measure these\neffects.",
        "positive": "Master equation approach to transient quantum transport in\n  nanostructures: In this review article, we present a non-equilibrium quantum transport theory\nfor transient electron dynamics in nanodevices based on exact master equation\nderived with the path integral method in the fermion coherent-state\nrepresentation. Applying the exact master equation to nanodevices, we also\nestablish the connection of the reduced density matrix and the transient\nquantum transport current with the Keldysh nonequilibrium Green functions. The\ntheory enables us to study transient quantum transport in nanostructures with\nback-reaction effects from the contacts, with non-Markovian dissipation and\ndecoherence being fully taken into account. In applications, we utilize the\ntheory to specific quantum transport systems, a variety of quantum decoherence\nand quantum transport phenomena involving the non-Markovian memory effect are\ninvestigated in both transient and stationary scenarios at arbitrary initial\ntemperatures of the contacts."
    },
    {
        "anchor": "Origin of Anomalous Water Permeation through Graphene Oxide Membrane: Water inside the low dimensional carbon structures has been considered\nseriously owing to fundamental interest in its flow and structures as well as\nits practical impact. Recently, the anomalous perfect penetration of water\nthrough graphene oxide membrane was demonstrated although the membrane was\nimpenetrable for other liquids and even gases. The unusual auxetic behavior of\ngraphene oxide in the presence of water was also reported. Here, based on\nfirst-principles calculations, we establish atomistic models for hybrid systems\ncomposed of water and graphene oxides revealing the anomalous water behavior\ninside the stacked graphene oxides. We show that formation of hexagonal ice\nbilayer in between the flakes as well as melting transition of ice at the edges\nof flakes are crucial to realize the perfect water permeation across the whole\nstacked structures. The distance between adjacent layers that can be controlled\neither by oxygen reduction process or pressure is shown to determine the water\nflow thus highlighting a unique water dynamics in randomly connected\ntwo-dimensional spaces.",
        "positive": "Formation of magnetic moments and resistance upturn at grain boundaries\n  of two-dimensional electron systems: Electronic correlations control the normal state of bulk high-Tc cuprates.\nStrong correlations also suppress the charge transport through cuprate grain\nboundaries (GBs). The question then arises if these correlations can produce\nmagnetic states at cuprate GBs. We analyze the formation of local magnetic\nmoments at the GB of a correlated two-dimensional electron systems which is\nrepresented by an inhomogeneous Hubbard model. The model Hamiltonian is\ndiagonalized after the implementation of a mean-field decoupling. The formation\nof local magnetic moments is supported by a sufficiently strong variance in the\nbond kinetic energies at the GB. Local scattering potentials can assist or\nsuppress the formation of a magnetic GB state, depending on the details of\ntheir spacial distribution. Grain boundary induced stripes are formed in the\nvicinity the GB and decay into the bulk. Moreover, we observe the build-up of\nconducting channels which are confined by magnetic clusters. The grain boundary\nresistance increases at decreasing temperatures. This low-temperature behavior\nis caused by the suppression of current correlations in the state with local\nmagnetic GB moments. The resistance upturn at low temperatures is in\nqualitative agreement with experiments."
    },
    {
        "anchor": "Current-induced torques in textured Rashba ferromagnets: In systems with small spin-orbit coupling, current-induced torques on the\nmagnetization require inhomogeneous magnetization textures. For large\nspin-orbit coupling, such torques exist even without gradients in the\nmagnetization direction. Here, we consider current-induced torques in\nferromagnetic metals with both Rashba spin-orbit coupling and inhomogeneous\nmagnetization. We first phenomenologically construct all torques that are\nallowed by the symmetries of the system, to first order in\nmagnetization-direction gradients and electric field. Second, we use a\nBoltzmann approach to calculate the spin torques that arise to second order in\nthe spin-orbit coupling. We apply our results to current-driven domain walls\nand find that the domain-wall mobility is strongly affected by torques that\nresult from the interplay between spin-orbit coupling and inhomogeneity of the\nmagnetization texture.",
        "positive": "Magneto-Optical Detection of the Orbital Hall Effect in Chromium: The orbital Hall effect has been theoretically predicted but its direct\nobservation is a challenge. Here, we report the magneto-optical detection of\ncurrent-induced orbital accumulation at the surface of a light 3$d$ transition\nmetal, Cr. The orbital polarization is in-plane, transverse to the current\ndirection, and scales linearly with current density, consistent with the\norbital Hall effect. Comparing the thickness-dependent magneto-optical\nmeasurements with $\\textit{ab initio}$ calculations, we estimate an orbital\ndiffusion length in Cr of $6.6\\pm 0.6$ nm."
    },
    {
        "anchor": "Logical Majorana zero modes in a nanowire network: We present a scheme to use physical Majorana quasi-zero modes at each\njunction of a two-dimensional nanowire network to build a logical Majorana zero\nmode, the location of which is controllable through gate voltages. The\nwire-network is a way to realize a proposal by Yang et al. arXiv:1808.04825 to\nimprint a Kekul\\'e vortex pattern on a honeycomb lattice via gate voltages. We\nshow that a specific type of junction -- other than a naive Y- or T-junction --\nis needed to realize, without breaking time-reversal symmetry, an artificial\n``graphene'' system with Majorana fermions instead of complex ones at each\nsite. The junction we propose (i) traps exactly one physical Majorana\n(quasi-)zero mode at each site of either a brick wall or honeycomb lattice and\n(ii) allows this mode to hybridize with all three neighboring sites. Using a\nlattice of these junctions and starting from an electronic, tight-binding model\nfor the wires, we imprint the voltage patterns corresponding to the Kekul\\'e\nvortex and observe the emergence of the logical Majorana zero mode at the\nvortex core. We also provide the range of parameters where this excitation\ncould be realized experimentally.",
        "positive": "Edge Current of FQHE and Aharanov-Bhom Type Phase: When two non-identical quasi-particles in the Hall fluid encircle each other,\nrelative AB type phase developes.As the quasi-particles advance towards the\nedge in a similar circular way, the developed current should have connection\nwith this AB type phase through the {\\it Shift} quantum number or Berry's\ntopological phase. We have pointed out the role of relative AB type statistical\nphase in the development of edge current.In fact,the physics of the current\nflow in FQHE is sketched here from the topological point of phase\ntransformation."
    },
    {
        "anchor": "Nonlinear magnetotransport in MoTe${}_2$: The shape of the Fermi surface influences many physical phenomena in\nmaterials and a growing interest in how the spin-dependent properties are\nrelated to the fermiology of crystals has surged. Recently, a novel\ncurrent-dependent nonlinear magnetoresistance effect, known as bilinear\nmagnetoelectric resistance (BMR), has been shown to be not only sensitive to\nthe spin-texture in spin-polarized non-magnetic materials, but also dependent\non the convexity of the Fermi surface in topological semimetals. In this paper,\nwe show that the temperature dependence of the BMR signal strongly depends on\nthe crystal axis of the semimetallic MoTe${}_2$. For the a-axis, the amplitude\nof the signal remains fairly constant, while for the b-axis it reverses sign at\nabout 100 K. We calculate the BMR efficiencies at 10 K to be $\\chi^{J}_{A} =\n(100\\pm3)$ nm${}^2$T${}^{-1}$A${}^{-1}$ and $\\chi^{J}_{B} = (-364\\pm13)$\nnm${}^2$T${}^{-1}$A${}^{-1}$ for the a- and b-axis, respectively, and we find\nthat they are comparable to the efficiencies measured for WTe${}_2$. We use\ndensity functional theory calculations to compute the Fermi surfaces of both\nphases at different energy levels and we observe a change in convexity of the\nouter-most electron pocket as a function of the Fermi energy. Our results\nsuggest that the BMR signal is mostly dominated by the change in the Fermi\nsurface convexity.",
        "positive": "Excitonic effects in the optical conductivity of gated graphene: We study the effect of electron-electron interactions in the optical\nconductivity of graphene under applied bias and derive a generalization of\nElliot's formula, commonly used for semiconductors, for the optical intensity.\nWe show that {\\it excitonic resonances} are responsible for several features of\nthe experimentally measured mid-infrared response of graphene such as the\nincrease of the conductivity beyond the \"universal\" value above the Fermi\nblocked regime, the broadening of the absorption at the threshold, and the\ndecrease of the optical conductivity at higher frequencies. Our results are\nalso in agreement with {\\it ab initio} calculations in the neutral regime."
    },
    {
        "anchor": "Exchange magnetic field torques in YIG/Pt bilayers observed by the\n  spin-Hall magnetoresistance: The effective field torque of an yttrium-iron-garnet film on the spin\naccumulation in an attached Pt film is measured by the spin-Hall\nmagnetoresistance (SMR). As a result, the magnetization direction of a\nferromagnetic insulating layer can be measured electrically. Experimental\ntransverse and longitudinal resistances are well described by the theoretical\nmodel of SMR in terms of the direct and inverse spin-Hall effect, for different\nPt thicknesses [3, 4, 8 and 35nm]. Adopting a spin-Hall angle of Pt\n$\\theta_{SH}=0.08$, we obtain the spin diffusion length of Pt\n($\\lambda=1.1\\pm0.3$nm) as well as the real\n($G_r=(7\\pm3)\\times10^{14}\\Omega^{-1}$m$^{-2}$) and imaginary part\n($G_i=(5\\pm3)\\times10^{13}\\Omega^{-1}$m$^{-2}$) of the spin-mixing conductance\nand their ratio ($G_r/G_i=16\\pm4$).",
        "positive": "Strain-induced large injection current in twisted bilayer graphene: The electronic wavefunctions in moir\\'e materials are highly sensitive to the\ndetails of the local atomic configuration enabling Bloch band geometry and\ntopology to be controlled by stacking and strain. Here we predict that large\ninjection currents (under circular polarized irradiation) can develop in\nstrained twisted bilayer graphene (TBG) heterostructures with broken sublattice\nsymmetry; such bulk photovoltaic currents flow even in the absence of a p-n\njunction and can be controlled by the helicity of incident light. As we argue,\nlarge injection current rates proceed from strong and highly peaked interband\nBerry curvature dipole distributions (arising from the texturing of Bloch\nwavefunctions in strained TBG heterostructures). Strikingly, we find that TBG\ninjection current displays pronounced responses in the THz regime and can be\ntuned by chemical potential. These render injection currents a useful\nphotocurrent probe of symmetry breaking in TBG heterostructures and make TBG a\npromising material for THz technology."
    },
    {
        "anchor": "Topological edge state engineering with high-frequency electromagnetic\n  radiation: We outline here how strong light-matter interaction can be used to induce\nquantum phase transition between normal and topological phases in\ntwo-dimensional topological insulators. We consider the case of a HgTe quantum\nwell, in which band inversion occurs above a critical value of the well\nthickness, and demonstrate that coupling between electron states and the $E$\nfield from an off-resonant linearly polarized laser provides a powerful tool to\ncontrol topological transitions, even for a thickness of the quantum well that\nis below the critical value. We also show that topological phase properties of\nthe edge states, including their group velocity, can be tuned in a controllable\nway by changing the intensity of the laser field. These findings open up the\npossibility for new experimental means with which to investigate topological\ninsulators and shed new light on topological-insulator-based technologies that\nare under active discussion.",
        "positive": "Direct Imaging of Dynamic Glassy Behavior in a Strained Manganite Film: Complex many-body interaction in perovskite manganites gives rise to a strong\ncompetition between ferromagnetic metallic and charge ordered phases with\nnanoscale electronic inhomogeneity and glassy behaviors. Investigating this\nglassy state requires high resolution imaging techniques with sufficient\nsensitivity and stability. Here, we present the results of a near-field\nmicrowave microscope imaging on the strain driven glassy state in a manganite\nfilm. The high contrast between the two electrically distinct phases allows\ndirect visualization of the phase separation. The low temperature microscopic\nconfigurations differ upon cooling with different thermal histories. At\nsufficiently high temperatures, we observe switching between the two phases in\neither direction. The dynamic switching, however, stops below the glass\ntransition temperature. Compared with the magnetization data, the phase\nseparation was microscopically frozen, while spin relaxation was found in a\nshort period of time."
    },
    {
        "anchor": "Quasiparticle decay rate of Josephson charge qubit oscillations: We analyze the decay of Rabi oscillations in a charge qubit consisting of a\nCooper pair box connected to a finite-size superconductor by a Josephson\njunction. We concentrate on the contribution of quasiparticles in the\nsuperconductors to the decay rate. Passing of a quasiparticle through the\nJosephson junction tunes the qubit away from the charge degeneracy, thus\nspoiling the Rabi oscillations. We find the temperature dependence of the\nquasiparticle contribution to the decay rate for open and isolated systems. The\nformer case is realized if a normal-state trap is included in the circuit, or\nif just one vortex resides in the qubit; the decay rate has an activational\ntemperature dependence with the activation energy equal to the superconducting\ngap $\\Delta$. In a superconducting qubit isolated from the environment, the\nactivation energy equals $2\\Delta$ if the number of electrons is even, while\nfor an odd number of electrons the decay rate of an excited qubit state remains\nfinite in the limit of zero temperature. We estimate the decay rate for\nrealistic parameters of a qubit.",
        "positive": "Raman Spectroscopy of Electrochemically-Gated Graphene Transistors:\n  Geometrical Capacitance, Electron-Phonon, Electron-Electron, and\n  Electron-Defect Scattering: We report a comprehensive micro-Raman scattering study of\nelectrochemically-gated graphene field-effect transistors. The geometrical\ncapacitance of the electrochemical top-gates is accurately determined from\ndual-gated Raman measurements, allowing a quantitative analysis of the\nfrequency, linewidth and integrated intensity of the main Raman features of\ngraphene. The anomalous behavior observed for the G-mode phonon is in very good\nagreement with theoretical predictions and provides a measurement of the\nelectron-phonon coupling constant for zone-center ($\\Gamma$ point) optical\nphonons. In addition, the decrease of the integrated intensity of the 2D-mode\nfeature with increasing doping, makes it possible to determine the\nelectron-phonon coupling constant for near zone-edge (K and K' points) optical\nphonons. We find that the electron-phonon coupling strength at $\\Gamma$ is five\ntimes weaker than at K (K'), in very good agreement with a direct measurement\nof the ratio of the integrated intensities of the resonant intra- (2D') and\ninter-valley (2D) Raman features. We also show that electrochemical reactions,\noccurring at large gate biases, can be harnessed to efficiently create defects\nin graphene, with concentrations up to approximately $1.4\\times 10^{12}~\\rm\ncm^{-2}$. At such defect concentrations, we estimate that the electron-defect\nscattering rate remains much smaller than the electron-phonon scattering rate.\nThe evolution of the G- and 2D-mode features upon doping remain unaffected by\nthe presence of defects and the doping dependence of the D mode closely follows\nthat of its two-phonon (2D mode) overtone. Finally, the linewidth and frequency\nof the G-mode phonon as well as the frequencies of the G- and 2D-mode phonons\nin doped graphene follow sample-independent correlations that can be utilized\nfor accurate estimations of the charge carrier density."
    },
    {
        "anchor": "Semimetalic graphene in a modulated electric potential: The $\\pi$-electronic structure of graphene in the presence of a modulated\nelectric potential is investigated by the tight-binding model. The low-energy\nelectronic properties are strongly affected by the period and field strength.\nSuch a field could modify the energy dispersions, destroy state degeneracy, and\ninduce band-edge states. It should be noted that a modulated electric potential\ncould make semiconducting graphene semimetallic, and that the onset period of\nsuch a transition relies on the field strength. There exist infinite\nFermi-momentum states in sharply contrast with two crossing points (Dirac\npoints) for graphene without external fields. The finite density of states\n(DOS) at the Fermi level means that there are free carriers, and, at the same\ntime, the low DOS spectrum exhibits many prominent peaks, mainly owing to the\nband-edge states.",
        "positive": "Interaction imaging with amplitude-dependence force spectroscopy: Knowledge of surface forces is the key to understanding a large number of\nprocesses in fields ranging from physics to material science and biology. The\nmost common method to study surfaces is dynamic atomic force microscopy (AFM).\nDynamic AFM has been enormously successful in imaging surface topography, even\nto atomic resolution, but the force between the AFM tip and the surface remains\nunknown during imaging. Here, we present a new approach that combines high\naccuracy force measurements and high resolution scanning. The method, called\namplitude-dependence force spectroscopy (ADFS) is based on the\namplitude-dependence of the cantilever's response near resonance and allows for\nseparate determination of both conservative and dissipative tip-surface\ninteractions. We use ADFS to quantitatively study and map the nano-mechanical\ninteraction between the AFM tip and heterogeneous polymer surfaces. ADFS is\ncompatible with commercial atomic force microscopes and we anticipate its\nwide-spread use in taking AFM toward quantitative microscopy."
    },
    {
        "anchor": "State Orthogonalization by Building a Hilbert Space: A New Approach to\n  Electronic Quantum Transport in Molecular Wires: Quantum descriptions of many complex systems are formulated most naturally in\nbases of states that are not mutually orthogonal. We introduce a general and\npowerful yet simple approach that facilitates solving such models exactly by\nembedding the non-orthogonal states in a new Hilbert space in which they are by\ndefinition mutually orthogonal. This novel approach is applied to electronic\ntransport in molecular quantum wires and is used to predict conductance\nantiresonances of a new type that arise solely out of the non-orthogonality of\nthe local orbitals on different sites of the wire.",
        "positive": "A comparison of a commercial hydrodynamics TCAD solver and Fermi\n  kinetics transport convergence for GaN HEMTs: Various simulations of a GaN HEMT are used to study the behaviors of two\ndifferent energy-transport models: the Fermi kinetics transport model and a\nhydrodynamics transport model as it is implemented in the device simulator\nSentaurus from Synopsys. The electron transport and heat flow equations of the\nrespective solvers are described in detail. The differences in the description\nof electron flux and the discretization methods are highlighted. Next, the\ntransport models are applied to the same simulated device structure using\nidentical meshes, boundary conditions, and material parameters. Static\nsimulations show the numerical convergence of Fermi kinetics to be consistently\nquadratic or faster, whereas the hydrodynamic model is often sub-quadratic.\nFurther comparisons of large signal transient simulations reveal the\nhydrodynamic model produces certain anomalous electron ensemble behaviors\nwithin the transistor structure. The fundamentally different electron dynamics\nproduced by the two models suggest an underlying cause for their different\nnumerical convergence characteristics."
    },
    {
        "anchor": "Electron-Electron Interactions in Isolated and Realistic Quantum Dots: A\n  Density Functional Theory Study: We use Kohn-Sham spin-density-functional theory to study the statistics of\nground-state spin and the spacing between conductance peaks in the Coulomb\nblockade regime for both 2D isolated and realistic quantum dots. We make a\nsystematic investigation of the effects of electron-electron interaction\nstrength and electron number on both the peak spacing and spin distributions. A\ndirect comparison between the distributions from isolated and realistic dots\nshows that, despite the difference in the boundary conditions and confining\npotential, the statistical properties are qualitatively the same. Strong\neven/odd pairing in the peak spacing distribution is observed only in the weak\ne-e interaction regime and vanishes for moderate interactions. The probability\nof high spin ground states increases for stronger e-e interaction and seems to\nsaturate around $r_s \\sim 4$. The saturated value is larger than previous\ntheoretical predictions. Both spin and conductance peak spacing distributions\nshow substantial variation as the electron number increases, not saturating\nuntil $N \\sim 150$. To interpret our numerical results, we analyze the spin\ndistribution in the even $N$ case using a simple two-level model.",
        "positive": "Coexisting and interacting spin torque driven free and reference layer\n  magnetic droplet solitons: Magnetic droplets are nanoscale, non-topological, magnetodynamical solitons\nthat can be nucleated in spin torque nano-oscillators (STNOs) or spin Hall\nnano-oscillators (SHNOs). All theoretical, numerical, and experimental droplet\nstudies have so far focused on the free layer (FL), and any additional dynamics\nin the reference layer (RL) have been entirely ignored. Here we show, using\nall-perpendicular STNOs, that there is not only significant magnetodynamics in\nthe RL, but the reference layer itself can host a droplet coexisting with the\nFL droplet. Both droplets are observed experimentally as stepwise changes and\nsharp peaks in the dc and differential resistance, respectively. Whereas the\nsingle FL droplet is highly stable, the coexistence state exhibits high-power\nbroadband microwave noise. Micromagnetic simulations corroborate the\nexperimental results and reveal a strong interaction between the droplets. Our\ndemonstration of strongly interacting and closely spaced droplets offers a\nunique platform for fundamental studies of highly non-linear soliton pair\ndynamics."
    },
    {
        "anchor": "An organic nanoparticle transistor behaving as a biological synapse: Molecule-based devices are envisioned to complement silicon devices by\nproviding new functions or already existing functions at a simpler process\nlevel and at a lower cost by virtue of their self-organization capabilities.\nMoreover, they are not bound to von Neuman architecture and this feature may\nopen the way to other architectural paradigms. Neuromorphic electronics is one\nof them. Here we demonstrate a device made of molecules and nanoparticles, a\nnanoparticle organic memory filed-effect transistor (NOMFET), which exhibits\nthe main behavior of a biological spiking synapse. Facilitating and depressing\nsynaptic behaviors can be reproduced by the NOMFET and can be programmed. The\nsynaptic plasticity for real time computing is evidenced and described by a\nsimple model. These results open the way to rate coding utilization of the\nNOMFET in dynamical neuromorphic computing circuits.",
        "positive": "Resonant modes in strain-induced graphene superlattices: We study tunneling across a strain-induced superlattice in graphene. In\nstudying the effect of applied strain on the low-lying Dirac-like spectrum,\nboth a shift of the Dirac points in reciprocal space, and a deformation of the\nDirac cones is explicitly considered. The latter corresponds to an anisotropic,\npossibly non-uniform, Fermi velocity. Along with the modes with unit\ntransmission usually found across a single barrier, we analytically find\nadditional resonant modes when considering a periodic structure of several\nstrain-induced barriers. We also study the band-like spectrum of bound states,\nas a function of conserved energy and transverse momentum. Such a\nstrain-induced superlattice may thus effectively work as a mode filter for\ntransport in graphene."
    },
    {
        "anchor": "Coherent spin manipulation in an exchange-only qubit: Initialization, manipulation, and measurement of a three-spin qubit are\ndemonstrated using a few-electron triple quantum dot, where all operations can\nbe driven by tuning the nearest-neighbor exchange interaction. Multiplexed\nreflectometry, applied to two nearby charge sensors, allows for qubit readout.\nDecoherence is found to be consistent with predictions based on gate voltage\nnoise with a uniform power spectrum. The theory of the exchange-only qubit is\ndeveloped and it is shown that initialization of only two spins suffices for\noperation. Requirements for full multi-qubit control using only exchange and\nelectrostatic interactions are outlined.",
        "positive": "Heat-transfer fingerprint of Josephson breathers: A sine-Gordon breather enhances the heat transfer in a thermally biased long\nJosephson junction. This solitonic channel allows for the tailoring of the\nlocal temperature throughout the system. Furthermore, the phenomenon implies a\nclear thermal fingerprint for the breather, and thus a 'non-destructive'\nbreather detection strategy is proposed here. Distinct breathing frequencies\nresult in morphologically different local temperature peaks, which can be\nidentified in an experiment."
    },
    {
        "anchor": "Double exceptional links in a three-dimensional dissipative cold atomic\n  gas: We explore the topological properties of non-Hermitian nodal-link semimetals\nwith dissipative cold atoms in a three-dimensional optical lattice. We\nconstruct a two-band continuum model in three dimensions with a spin-dependent\ngain and loss, where the exceptional points in the energy spectrum can comprise\na double Hopf link. The topology of the bulk band is characterized by a winding\nnumber defined for a one-dimensional loop in the momentum space and a\ntopological transition of the nodal structures emerges as the change of the\nnon-Hermiticity strength. A non-Bloch theory is built to describe the\ncorresponding lattice model which has anomalous bulk-boundary correspondence.\nFurthermore, we propose that the model can be realized using ultracold\nfermionic atoms in an optical lattice and the exceptional nodal links as well\nas the topological properties can be detected by measuring the atomic spin\ntextures.",
        "positive": "Spin light emitting diode based on exciton fine structure tuning in\n  quantum dots: We propose a concept of quantum dot based light emitting diode that produces\ncircularly polarized light due to the tuning of the exciton fine structure by\nmagnetic field and electron nuclear hyperfine interaction. The device operates\nunder injection of electrons and holes from nonmagnetic contacts in a small\nfield of the order of milliteslas. Its size can be parametrically smaller than\nthe light wavelength, and circular polarization degree of electroluminescence\ncan reach 100%. The proposed concept is compatible with the micropillar\ncavities, which allows for the deterministic electrical generation of single\ncircularly polarized photons."
    },
    {
        "anchor": "Quantum Manipulation of Valleys in Bilayer Graphene: Theory and\n  Applications: Quantum manipulation of valleys in bilayer graphene is investigated. We\nestablish an effective Schrodinger model, and identify two key mechanisms for\nvalley manipulation - band structure warping and generalized valley-orbit\ninteraction. Specifically, we implement valley qubits / FETs in bilayer\ngraphene, as prospective quantum devices to build valley-based quantum /\nclassical information processing.",
        "positive": "Internal degrees of freedom and transport of benzene on graphite: In this paper, the chaotic internal degrees of freedom of a benzene molecule\nadsorbed on a graphite substrate, their interplay with thermal noise, and their\neffects on the diffusion and drift are investigated analytically by making use\nof the presence of two different time scales as well as by molecular-dynamics\nsimulations. The effects of thermal noise are investigated, and it is found\nthat noise does not significantly alter the dynamics of the internal degrees of\nfreedom, yet affects the friction and diffusion of the center of mass.\nQualitative and quantitative theoretical predictions for the friction and\ndiffusion of the molecule on the substrate are made and are compared to\nmolecular-dynamics simulations. Contributions to the friction and diffusion\nfrom the finite heat bath as well as the slow dynamics of the center of mass\nare formally identified. It is shown that the torsion in benzene, which\ndominates the nonlinear coupling, significantly affects the friction of the\nmolecule on the surface. The results compare favorably with recent results from\nHe/neutron spin echo experiments on this system. Based on the analytical and\nnumerical results, some suggestions are made for experimental conditions under\nwhich the effects of internal degrees of freedom might be observable."
    },
    {
        "anchor": "Inelastic scattering in a monolayer graphene sheet; a weak-localization\n  study: Charge carriers in a graphene sheet, a single layer of graphite, exhibit much\ndistinctive characteristics to those in other two-dimensional electronic\nsystems because of their chiral nature. In this report, we focus on the\nobservation of weak localization in a graphene sheet exfoliated from a piece of\nnatural graphite and nano-patterned into a Hall-bar geometry. Much stronger\nchiral-symmetry-breaking elastic intervalley scattering in our graphene sheet\nrestores the conventional weak localization. The resulting carrier-density and\ntemperature dependence of the phase coherence length reveal that the\nelectron-electron interaction including a direct Coulomb interaction is the\nmain inelastic scattering factor while electron-hole puddles enhance the\ninelastic scattering near the Dirac point.",
        "positive": "Photo-assisted spin transport in double quantum dots with spin-orbit\n  interaction: We investigate the effect of spin-orbit interaction on the intra- and\ninterdot particle dynamics of a double quantum dot under ac electric fields.\nThe former is modeled as an effective ac magnetic field that produces\nelectric-dipole spin resonance transitions, while the latter is introduced via\nspin-flip tunneling amplitudes. We observe the appearance of non-trivial\nspin-polarized dark states, arising from an ac-induced interference between\nphoto-assisted spin-conserving and spin-flip tunneling processes. These dark\nstates can be employed to precisely measure the spin-orbit coupling in quantum\ndot systems. Furthermore, we show that the interplay between photo-assisted\ntransitions and spin-flip tunneling allows the system to operate as a highly\ntunable spin filter. Finally, we investigate the operation of the system as a\nresonant flopping-mode qubit for arbitrary ac voltage amplitudes, allowing for\nhigh tunability and enhanced qubit control possibilities."
    },
    {
        "anchor": "Holographic convergent electron beam diffraction (CBED) imaging of\n  two-dimensional crystals: Convergent beam electron diffraction (CBED) performed on two-dimensional (2D)\nmaterials recently emerged as a powerful tool to study structural and stacking\ndefects, adsorbates, atomic 3D displacements in the layers, and the interlayer\ndistances. The formation of the interference patterns in individual CBED spots\nof 2D crystals can be considered as a hologram, thus the CBED patterns can be\ndirectly reconstructed by conventional reconstruction methods adapted from\nholography. In this study, we review recent results applying CBED to 2D\ncrystals and their heterostructures: holographic CBED on bilayers with the\nreconstruction of defects and the determination of interlayer distance, CBED on\n2D crystal monolayers to reveal adsorbates, and CBED on multilayered van der\nWaals systems with moir\\'e patterns for local structural determination.",
        "positive": "Conductance of nano-systems with interactions coupled via conduction\n  electrons: Effect of indirect exchange interactions: A nano-system in which electrons interact and in contact with Fermi leads\ngives rise to an effective one-body scattering which depends on the presence of\nother scatterers in the attached leads. This non local effect is a pure\nmany-body effect that one neglects when one takes non interacting models for\ndescribing quantum transport. This enhances the non-local character of the\nquantum conductance by exchange interactions of a type similar to the\nRKKY-interaction between local magnetic moments. A theoretical study of this\neffect is given assuming the Hartree-Fock approximation for spinless fermions\nin an infinite chain embedding two scatterers separated by a segment of length\nL\\_c. The fermions interact only inside the two scatterers. The dependence of\none scatterer onto the other exhibits oscillations which decay as 1/L\\_c and\nwhich are suppressed when L\\_c exceeds the thermal length L\\_T. The\nHartree-Fock results are compared with exact numerical results obtained with\nthe embedding method and the DMRG algorithm."
    },
    {
        "anchor": "3d Transition Metal Adsorption Induced Vally-polarized Anomalous Hall\n  Effect in Germanene: Based on DFT+U and Berry curvature calculations, we study the electronic\nstructures and topological properties of 3d transition metal (TM) atom (from Ti\nto Co) adsorbed germanene (TM-germanene). We find that valley-polarized\nanomalous hall effect (VAHE) can be realized in germanene by adsorbing Cr, Mn,\nor Co atom on its surface. A finite valley hall voltage can be easily detected\nin its nanoribbon, which is important for valleytronics devices. Moreover,\ndifferent valley-polarized current and even reversible valley Hall voltage can\nbe archived by shifting the Fermi energy of the systems. Such versatile\nfeatures of the systems show potential in next generation electronics devices.",
        "positive": "Electrical and thermal transport in coplanar polycrystalline\n  graphene-hBN heterostructures: We present a theoretical study of electronic and thermal transport in\npolycrystalline heterostructures combining graphene (G) and hexagonal boron\nnitride (hBN) grains of varying size and distribution. By increasing the hBN\ngrain density from a few percents to $100\\%$, the system evolves from a good\nconductor to an insulator, with the mobility dropping by orders of magnitude\nand the sheet resistance reaching the M$\\Omega$ regime. The Seebeck coefficient\nis suppressed above $40\\%$ mixing, while the thermal conductivity of\npolycrystalline hBN is found to be on the order of $30-120\\,{\\rm W}{\\rm\nm}^{-1}{\\rm K}^{-1}$. These results, agreeing with available experimental data,\nprovide guidelines for tuning G-hBN properties in the context of\ntwo-dimensional materials engineering. In particular, while we proved that both\nelectrical and thermal properties are largely affected by morphological\nfeatures (like e.g. by the grain size and composition), we find in all cases\nthat nm-sized polycrystalline G-hBN heterostructures are not good\nthermoelectric materials."
    },
    {
        "anchor": "Enhancement and termination of the superconducting proximity effect due\n  to atomic-scale defects visualized by scanning tunneling microscopy: Using low-temperature scanning tunneling microscopy and spectroscopy, we have\nstudied the proximity effect at the interfaces between superconducting Pb\nisland structures and metallic Pb-induced striped-incommensurate phase formed\non a Si(111) substrate. Our real-space observation revealed that the step\nstructures on the two-dimensional metallic layer exhibit significant roles on\nthe propagation of the superconducting pair correlation; the proximity effect\nis terminated by the steps, and in the confined area by the interface and the\nsteps the effect is enhanced. The observed results are explained quantitatively\nwith an elastic reflection of electrons at the step edges based on calculations\nwith the quasi-classical Green's function formulation using Usadel equation.",
        "positive": "Chirality dependent frequency shift of radial breathing mode in metallic\n  carbon nanotubes: A phonon frequency shift of the radial breathing mode for metallic single\nwall carbon nanotubes is predicted as a function of Fermi energy. Armchair\nnanotubes do not show any frequency shift while zigzag nanotubes exhibit phonon\nsoftening, but this softening is not associated with the broadening. This\nchirality dependence originates from a curvature-induced energy gap and a\nspecial electron-phonon coupling mechanism for radial breathing modes. Because\nof the particle-hole symmetry, only the off-site deformation potential\ncontributes to the frequency shift. On the other hand, the on-site potential\ncontributes to the Raman intensity, and the radial breathing mode intensity is\nstronger than that of the $G$ band. The relationship between the chirality\ndependence of the frequency shift of the radial breathing mode and the $\\Gamma$\npoint optical phonon frequency shift is discussed."
    },
    {
        "anchor": "Possible evidence of non-Fermi liquid behavior from\n  quasi-one-dimensional indium nanowires: We report possible evidence of non-Fermi liquid (NFL) observed at room\ntemperature from the quasi one-dimensional (1D) indium (In) nanowires\nself-assembled on Si(111)-7$\\times$7 surface. Using high-resolution\nelectron-energy-loss spectroscopy, we have measured energy and width\ndispersions of a low energy intrasubband plasmon excitation in the In\nnanowires. We observe the energy-momentum dispersion $\\omega$(q) in the low q\nlimit exactly as predicted by both NFL theory and the\nrandom-phase-approximation. The unusual non-analytic width dispersion $\\zeta(q)\n\\sim q^{\\alpha}$ measured with an exponent ${\\alpha}$=1.40$\\pm$0.24, however,\nis understood only by the NFL theory. Such an abnormal width dispersion of low\nenergy excitations may probe the NFL feature of a non-ideal 1D interacting\nelectron system despite the significantly suppressed spin-charge separation\n($\\leq$40 meV).",
        "positive": "Topological insulators and geometry of vector bundles: For a long time, band theory of solids has focused on the energy spectrum, or\nHamiltonian eigenvalues. Recently, it was realized that the collection of\neigenvectors also contains important physical information. The local geometry\nof eigenspaces determines the electric polarization, while their global\ntwisting gives rise to the metallic surface states in topological insulators.\nThese phenomena are central topics of the present notes. The shape of\neigenspaces is also responsible for many intriguing physical analogies, which\nhave their roots in the theory of vector bundles. We give an informal\nintroduction to the geometry and topology of vector bundles and describe\nvarious physical models from this mathematical perspective."
    },
    {
        "anchor": "Quantum Hall effect at low magnetic fields due to electron-electron\n  interaction: A Comment on cond-mat/9906450 (published in Phys. Rev. Lett. 84,\n  3141 (2000)): In a recent preprint cond-mat/9906450 (published in PRL 84, 3141 (2000)) Bodo\nHuckestein showed that at real experimental conditions it is not possible to\nobserve the quantum Hall effect (QHE) at $\\omega_{c}\\tau <1$ predicted by\nKhmelnitskii ($\\omega_{c}=eB/m$ is the cyclotron frequency and $\\tau $ is the\nscattering time). We would like to point out here that in fact the situation is\nnot so hopeless due to the influence of the electron-electron interaction.",
        "positive": "First-principles calculation on the transport properties of molecular\n  wires between Au clusters under equilibrium: Based on the matrix Green's function method combined with hybrid\ntight-binding / density functional theory, we calculate the conductances of a\nseries of gold-dithiol molecule-gold junctions including benzenedithiol (BDT),\nbenzenedimethanethiol (BDMT), hexanedithiol (HDT), octanedithiol (ODT) and\ndecanedithiol (DDT). An atomically-contacted extended molecule model is used in\nour calculation. As an important procedure, we determine the position of the\nFermi level by the energy reference according to the results from ultraviolet\nphotoelectron spectroscopy (UPS) experiments. After considering the\nexperimental uncertainty in UPS measurement, the calculated results of\nmolecular conductances near the Fermi level qualitatively agree with the\nexperimental values measured by Tao et. al. [{\\it Science} 301, 1221 (2003);\n{\\it J. Am. Chem. Soc.} 125, 16164 (2003); {\\it Nano. Lett.} 4, 267 (2004).]"
    },
    {
        "anchor": "Vector magnetometry using silicon vacancies in 4H-SiC at ambient\n  conditions: Point defects in solids promise precise measurements of various quantities.\nEspecially magnetic field sensing using the spin of point defects has been of\ngreat interest recently. When optical readout of spin states is used, point\ndefects achieve optical magnetic imaging with high spatial resolution at\nambient conditions. Here, we demonstrate that genuine optical vector\nmagnetometry can be realized using the silicon vacancy in SiC, which has an\nuncommon S=3/2 spin. To this end, we develop and experimentally test sensing\nprotocols based on a reference field approach combined with multi frequency\nspin excitation. Our works suggest that the silicon vacancy in an\nindustry-friendly platform, SiC, has potential for various magnetometry\napplications at ambient conditions.",
        "positive": "A six degree of freedom nanomanipulator design based on carbon nanotube\n  bundles: Scanning probe imaging and manipulation of matter is of crucial importance\nfor nanoscale science and technology. However, its resolution and ability to\nmanipulate matter at the atomic scale is limited by rather poor control over\nthe fine structure of the probe. In the present communication, a strategy is\nproposed to construct a molecular nanomanipulator from ultrathin single-walled\ncarbon nanotubes. Covalent modification of a nanotube cap at predetermined\natomic sites makes the nanotube act as a support for a functional \"tool-tip\"\nmolecule. Then, a small bundle of nanotubes (3 or 4) with aligned ends can act\nas an extremely high aspect ratio parallel nanomanipulator for a suspended\nmolecule, where protraction or retraction of individual nanotubes results in\ncontrolled tilting of the tool-tip in two dimensions. Together with the usual\nSPM three degrees of freedom and augmented with rotation of the system as a\nwhole, the design offers six degrees of freedom for imaging and manipulation of\nmatter with precision and freedom so much needed for advanced nanotechnology. A\nsimilar design might be possible to implement with other high-aspect ratio\nnanostructures, such as oxide nanowires."
    },
    {
        "anchor": "Pinning mode resonance of a Skyrme crystal near Landau level filling\n  factor $\u03bd$=1: Microwave pinning-mode resonances found around integer quantum Hall effects,\nare a signature of crystallized quasiparticles or holes. Application of\nin-plane magnetic field to these crystals, increasing the Zeeman energy, has\nnegligible effect on the resonances just below Landau level filling $\\nu=2$,\nbut increases the pinning frequencies near $\\nu=1$, particularly for smaller\nquasiparticle/hole densities. The charge dynamics near $\\nu=1$, characteristic\nof a crystal order, are affected by spin, in a manner consistent with a Skyrme\ncrystal.",
        "positive": "Intercalation and desorption of oxygen between graphene and Ru(0001)\n  studied with helium ion scattering: Graphene is a fascinating 2D material that is being widely investigated for\nuse in electronic devices due to its unique electronic and materials\nproperties. Also, because of its high thermal stability and inertness, it is\nconsidered a promising candidate for use as a protection layer for metal\nsubstrates. Here, graphene films grown on Ru(0001) are held at 600 K while\nreacted with oxygen (O$_2$) and then investigated with helium low energy ion\nscattering (LEIS). LEIS spectra collected at different scattering angles\nconfirm that oxygen does not adsorb to graphene, but instead intercalates\nbetween the graphene and the substrate. The intercalated O$_2$ desorbs when the\nsample is annealed to 800 K. It is shown that this is a much lower temperature\nthan is needed to remove chemisorbed atomic oxygen from Ru, thus inferring that\nthe intercalated oxygen is molecular. During the desorption process, some of\nthe graphene is etched away via a chemical reaction with the oxygen, with the\nproportion desorbing as O$_2$ or reacting to etch the graphene being dependent\non the amount of intercalated O$_2$."
    },
    {
        "anchor": "Applicability of the Wide-Band Limit in DFT-Based Molecular Transport\n  Calculations: Transport properties of molecular junctions are notoriously expensive to\ncalculate with ab initio methods, primarily due to the semi-infinite\nelectrodes. This has led to the introduction of different approximation schemes\nfor the electrodes. For the most popular metals used in experiments, such as\ngold, the wide-band limit (WBL) is a particularly efficient choice. In this\npaper we investigate the performance of different WBL schemes relative to more\nsophisticated approaches including the fully self-consistent non-equilibrium\nGreen's function (NEGF) method. We find reasonably good agreement between all\nschemes for systems in which the molecule (and not the metal-molecule\ninterface) dominates the transport properties. Moreover, our implementation of\nthe WBL requires negligible computational effort compared to the ground state\nDFT calculation of a molecular junction. We also present a new approximate but\nefficient scheme for calculating transport with a finite bias. Provided the\nvoltage drop occurs primarily inside the molecule, this method provides results\nin reasonable agreement with fully self-consistent calculations.",
        "positive": "Resilient Intraparticle Entanglement and its Manifestation in Spin\n  Dynamics of Disordered Dirac Matter: Topological quantum matter exhibits novel transport phenomena driven by\nentanglement between internal degrees of freedom, as for instance generated by\nspin-orbit coupling effects. Here we report on a direct connection between the\nmechanism driving spin relaxation and the intertwined dynamics between spin and\nsublattice degrees of freedom in disordered graphene. Beyond having a direct\nobservable consequence, such intraparticle entanglement is shown to be\nresilient to disorder, pointing towards a novel resource for quantum\ninformation processing."
    },
    {
        "anchor": "Disordered ensembles of strongly coupled single-molecule plasmonic\n  picocavities as nonlinear optical metamaterials: We propose to use molecular picocavity ensembles as macroscopic coherent\nnonlinear optical devices enabled by nanoscale strong coupling. For a generic\npicocavity model that includes molecular and photonic disorder, we derive\ntheoretical performance bounds for coherent cross-phase modulation signals\nusing weak classical fields of different frequencies. We show that strong\ncoupling of the picocavity {\\it vacua} with a specific vibronic sideband in the\nmolecular emission spectrum results in a significant variation of the effective\nrefractive index of the metamaterial relative to a molecule-free scenario, due\nto a vacuum-induced Autler-Townes effect. For a realistic molecular disorder\nmodel, we demonstrate that cross-phase modulation of optical fields as weak as\n10 kW/cm$^2$ is feasible using dilute ensembles of molecular picocavities at\nroom temperature, provided that the confined vacuum is not resonantly driven by\nthe external probe field}. Our work paves the way for the development of\nplasmonic metamaterials that exploit strong coupling for optical state\npreparation and quantum control.",
        "positive": "Higher-order topological corner states induced by gain and loss: The concept of topological phases has been generalized to higher-order\ntopological insulators and superconductors with novel boundary states on\ncorners or hinges. Meanwhile, recent experimental advances in controlling\ndissipation (such as gain and loss) open new possibilities in studying\nnon-Hermitian topological phases. Here, we show that higher-order topological\ncorner states can emerge by simply introducing staggered on-site gain/loss to a\nHermitian system in trivial phases. For such a non-Hermitian system, we\nestablish a general bulk-corner correspondence by developing a biorthogonal\nnested-Wilson-loop and edge-polarization theory, which can be applied to a wide\nclass of non-Hermitian systems with higher-order topological orders. The theory\ngives rise to topological invariants characterizing the non-Hermitian\ntopological multipole moments (i.e., corner states) that are protected by\nreflection or chiral symmetry. Such gain/loss induced higher-order topological\ncorner states can be experimentally realized using photons in coupled cavities\nor cold atoms in optical lattices."
    },
    {
        "anchor": "Tailoring the switching efficiency of magnetic tunnel junctions by the\n  fieldlike spin-orbit torque: Current-induced spin-orbit torques provide a versatile tool for switching\nmagnetic devices. In perpendicular magnets, the dampinglike component of the\ntorque is the main driver of magnetization reversal. The degree to which the\nfieldlike torque assists the switching is a matter of debate. Here we study the\nswitching of magnetic tunnel junctions with a CoFeB free layer and either W or\nTa underlayers, which have a ratio of fieldlike to dampinglike torque of 0.3\nand 1, respectively. We show that the fieldlike torque can either assist or\nhinder the switching of CoFeB when the static in-plane magnetic field required\nto define the polarity of spin-orbit torque switching has a component\ntransverse to the current. In particular, the non-collinear alignment of the\nfield and current can be exploited to increase the switching efficiency and\nreliability compared to the standard collinear alignment. By probing individual\nswitching events in real-time, we also show that the combination of transverse\nmagnetic field and fieldlike torque can accelerate or decelerate the reversal\nonset. We validate our observations using micromagnetic simulations and\nextrapolate the results to materials with different torque ratios. Finally, we\npropose device geometries that leverage the fieldlike torque for density\nincrease in memory applications and synaptic weight generation.",
        "positive": "Spin and Charge Shot Noise in Mesoscopic Spin Hall Systems: Injection of unpolarized charge current through the longitudinal leads of a\nfour-terminal two-dimensional electron gas with the Rashba spin-orbit (SO)\ncoupling and/or SO scattering off extrinsic impurities is responsible not only\nfor the pure spin Hall current in the transverse leads, but also for random\ntime-dependent current fluctuations. We employ the scattering approach to\ncurrent-current correlations in multiterminal nanoscale conductors to analyze\nthe shot noise of transverse pure spin Hall and zero charge current, or\ntransverse spin current and non-zero charge Hall current, driven by unpolarized\nor spin-polarized longitudinal current, respectively. Since any spin-flip acts\nas an additional source of noise, we argue that these shot noises offer a\nunique tool to differentiate between intrinsic and extrinsic SO mechanisms\nunderlying the spin Hall effect in paramagnetic devices."
    },
    {
        "anchor": "Modeling electrolytically top gated graphene: We investigate doping of a single-layer graphene in the presence of\nelectrolytic top gating. The interfacial phenomena is modeled using a modified\nPoisson-Boltzmann equation for an aqueous solution of simple salt. We\ndemonstrate both the sensitivity of graphene's doping levels to the salt\nconcentration and the importance of quantum capacitance that arises due to the\nsmallness of the Debye screening length in the electrolyte.",
        "positive": "Dopant-controlled single-electron pumping through a metallic island: We investigate a hybrid metallic island / single dopant electron pump based\non fully-depleted silicon on insulator technology. Electron transfer between\nthe central metallic island and the leads is controlled by resonant tunneling\nthrough single phosphorus dopants in the barriers. Top gates above the barriers\nare used control the resonance conditions. Applying radio frequency signals to\nthe gates, non-adiabatic quantized electron pumping is achieved. A simple\ndeterministic model is presented and confirmed by comparing measurements with\nsimulations."
    },
    {
        "anchor": "Nuclear spin warm-up in bulk n-GaAs: We show that the spin-lattice relaxation in n-type insulating GaAs is\ndramatically accelerated at low magnetic fields. The origin of this effect,\nthat cannot be explained in terms of well-known diffusion-limited hyperfine\nrelaxation, is found in the quadrupole relaxation, induced by fluctuating donor\ncharges. Therefore, quadrupole relaxation, that governs low field nuclear spin\nrelaxation in semiconductor quantum dots, but was so far supposed to be\nharmless to bulk nuclei spins in the absence of optical pumping can be studied\nand harnessed in much simpler model environment of n-GaAs bulk crystal.",
        "positive": "Anisotropic electronic structure and transport properties of the\n  $\\mathcal{H}$-$0$ hyperhoneycomb lattice: Carbon, being one of the most versatile elements of the periodic table, forms\nsolids and molecules with often unusual properties. Recently, a novel family of\nthree-dimensional graphitic carbon structures, the so-called hyperhoneycomb\nlattices, has been proposed, with the possibility of being topological\ninsulators [K. Mullen, B. Uchoa and D. T. Glatzhofer, Phys. Rev. Lett. 115,\n026403 (2015)]. In this work, we present electronic structure calculations for\none member ($\\mathcal{H}$-0) of this family, using Density Functional Theory\nand non-equilibrium Green's functions transport calculations to show that the\n$\\mathcal{H}$-0 structure should have strongly anisotropic electronic\nproperties, being an insulator or a conductor depending on the crystalline\norientation chosen for transport. Calculations in the framework of Extended\nH\\\"uckel Theory indicate that these properties can only be understood if one\nconsiders at least $2^{nd}$ nearest-neighbor interactions between carbon atoms,\ninvalidating some of the conclusions of Ref. [K. Mullen, B. Uchoa and D. T.\nGlatzhofer, Phys. Rev. Lett. 115, 026403 (2015)], at least for this particular\nmaterial."
    },
    {
        "anchor": "Doping-control of excitons and magnetism in few-layer CrSBr: Magnetism in two-dimensional materials reveals phenomena distinct from bulk\nmagnetic crystals, with sensitivity to charge doping and electric fields in\nmonolayer and bilayer van der Waals magnet CrI3. Within the class of layered\nmagnets, semiconducting CrSBr stands out by featuring stability under ambient\nconditions, correlating excitons with magnetic order and thus providing strong\nmagnon-exciton coupling, and exhibiting peculiar magneto-optics of\nexciton-polaritons. Here, we demonstrate that both exciton and magnetic\ntransitions in bilayer and trilayer CrSBr are sensitive to voltage-controlled\nfield-effect charging, exhibiting bound exciton-charge complexes and\ndoping-induced metamagnetic transitions. Moreover, we demonstrate how these\nunique properties enable optical probes of local magnetic order, visualizing\nmagnetic domains of competing phases across metamagnetic transitions induced by\nmagnetic field or electrostatic doping. Our work identifies few-layer CrSBr as\na rich platform for exploring collaborative effects of charge, optical\nexcitations, and magnetism.",
        "positive": "Optical and plasmonic properties of twisted bilayer graphene: Impact of\n  interlayer tunneling asymmetry and ground-state charge inhomogeneity: We present a theoretical study of the local optical conductivity, plasmon\nspectra, and thermoelectric properties of twisted bilayer graphene (TBG) at\ndifferent filling factors and twist angles $\\theta$. Our calculations are based\non the electronic band structures obtained from a continuum model that has two\ntunable parameters, $u_0$ and $u_1$, which parametrize the intra-sublattice\ninter-layer and inter-sublattice inter-layer tunneling rate, respectively. In\nthis Article we focus on two key aspects: i) we study the dependence of our\nresults on the value of $u_0$, exploring the whole range $0\\leq u_0\\leq u_1$;\nii) we take into account effects arising from the intrinsic charge density\ninhomogeneity present in TBG, by calculating the band structures within the\nself-consistent Hartree approximation. At zero filling factor, i.e. at the\ncharge neutrality point, the optical conductivity is quite sensitive to the\nvalue of $u_0$ and twist angle, whereas the charge inhomogeneity brings about\nonly modest corrections. On the other hand, away from zero filling, static\nscreening dominates and the optical conductivity is appreciably affected by the\ncharge inhomogeneity, the largest effects being seen on the intra-band\ncontribution to it. These findings are also reflected by the plasmonic spectra.\nWe compare our results with existing ones in the literature, where effects i)\nand ii) above have not been studied systematically. As natural byproducts of\nour calculations, we obtain the Drude weight and Seebeck coefficient. The\nformer displays an enhanced particle-hole asymmetry stemming from the\ninhomogeneous ground-state charge distribution. The latter is shown to display\na broad sign-changing feature even at low temperatures ($\\approx 5~{\\rm K}$)\ndue to the reduced slope of the bands, as compared to those of single-layer\ngraphene."
    },
    {
        "anchor": "Mean Field Theory of the Kondo Effect in Quantum Dots with an Even\n  Number of Electrons: We investigate the enhancement of the Kondo effect in quantum dots with an\neven number of electrons, using a scaling method and a mean field theory. We\nevaluate the Kondo temperature $T_K$ as a function of the energy difference\nbetween spin-singlet and triplet states in the dot, $\\Delta$, and the Zeeman\nsplitting, $E_Z$. If the Zeeman splitting is small, $E_Z \\ll T_K$, the\ncompetition between the singlet and triplet states enhances the Kondo effect.\n$T_K$ reaches its maximum around $\\Delta=0$ and decreases with $\\Delta$ obeying\na power law. If the Zeeman splitting is strong, $E_Z \\gg T_K$, the Kondo effect\noriginates from the degeneracy between the singlet state and one of the\ncomponents of the triplet state at $-\\Delta \\sim E_Z$. We show that $T_K$\nexhibits another power-law dependence on $E_Z$. The mean field theory provides\na unified picture to illustrate the crossover between these regimes. The\nenhancement of the Kondo effect can be understood in terms of the overlap\nbetween the Kondo resonant states created around the Fermi level. These\nresonant states provide the unitary limit of the conductance $G\\sim 2e^2/h$.",
        "positive": "Thermoelectric Properties of Electrostatically Tunable Antidot Lattices: We report on the fabrication and characterization of a device which allows\nthe formation of an antidot lattice (ADL) using only electrostatic gating. The\nantidot potential and Fermi energy of the system can be tuned independently.\nWell defined commensurability features in magnetoresistance as well as\nmagnetothermopower are obsereved. We show that the thermopower can be used to\nefficiently map out the potential landscape of the ADL."
    },
    {
        "anchor": "Zero-bias anomaly in a nanowire quantum dot coupled to superconductors: We studied the low-energy states of spin-1/2 quantum dots defined in InAs/InP\nnanowires and coupled to aluminium superconducting leads. By varying the\nsuperconducting gap, \\Delta, with a magnetic field, B, we investigated the\ntransition from strong coupling, \\Delta << T_{K}, to weak coupling, \\Delta >>\nT_{K}, where T_{K} is the Kondo temperature. Below the critical field, we\nobserve a persisting zero-bias Kondo resonance that vanishes only for low B or\nhigher temperatures, leaving the room to more robust sub-gap structures at bias\nvoltages between \\Delta and 2\\Delta. For strong and approximately symmetric\ntunnel couplings, a Josephson supercurrent is observed in addition to the Kondo\npeak. We ascribe the coexistence of a Kondo resonance and a superconducting gap\nto a significant density of intra-gap quasiparticle states, and the finite-bias\nsub-gap structures to tunneling through Shiba states. Our results, supported by\nnumerical calculations, own relevance also in relation to tunnel-spectroscopy\nexperiments aiming at the observation of Majorana fermions in hybrid\nnanostructures.",
        "positive": "Observations of two-fold shell filling and Kondo effect in a graphene\n  nano-ribbon quantum dot device: A graphene nanoribbon (GNR) with orientation along its principle axis was\nobtained through a mechanical tearing process, and a quantum dot device was\nfabricated from the GNR. We have studied the transport property of the GNR\nquantum dot device down to dilution refrigerator temperatures. Two-fold\ncharging periodicity was observed in the Coulomb-blockade measurement,\nsignaling a shell-filling process with broken valley degeneracy. In one of the\nsmaller Coulomb diamonds, Kondo-like resonance were observed, with two\nconductance peaks displaced symmetrically from the zero bias voltage. The\nsplitting of Kondo resonance at zero magnetic field suggests spin-polarization\nof the quantum dot, possibly due to the edge states of a zigzag GNR."
    },
    {
        "anchor": "Ferroelectric-like SrTiO3 surface dipoles probed by graphene: The electrical transport properties of graphene are greatly influenced by its\nenvironment. Owing to its high dielectric constant, strontium titanate (STO) is\nexpected to suppress the long-range charged impurity scattering and\nconsequently to enhance the mobility. However, the absence of such enhancement\nhas caused some controversies regarding the scattering mechanism. In graphene\ndevices transferred from SiO2 to STO using a newly developed technique, we\nobserve a moderate mobility enhancement near the Dirac point, which is the\npoint of charge neutrality achieved by adjusting the Fermi level. While bulk\nSTO is not known as a ferroelectric material, its surface was previously\nreported to exhibit an outward displacement of oxygen atoms and\nferroelectric-like dipole moment. When placed on STO, graphene shows strong and\nasymmetric hysteresis in resistivity, which is consistent with the dipole\npicture associated with the oxygen displacement. The hysteretic response of the\nsurface dipole moment diminishes the polarizability, therefore weakens the\nability of STO to screen the Coulomb potential of the impurities.",
        "positive": "Resonant circular photogalvanic effect in GaN/AlGaN heterojunctions: The resonant circular photogalvanic effect is observed in wurtzite\n(0001)-oriented GaN low-dimensional structures excited by infrared radiation.\nThe current is induced by angular momentum transfer of photons to the\nphotoexcited electrons at resonant inter-subband optical transitions in a\nGaN/AlGaN heterojunction. The signal reverses upon the reversal of the\nradiation helicity or, at fixed helicity, when the propagation direction of the\nphotons is reversed. Making use of the tunability of the free-electron laser\nFELIX we demonstrate that the current direction changes by sweeping the photon\nenergy through the intersubband resonance condition, in agreement with\ntheoretical considerations."
    },
    {
        "anchor": "Phase coherent transmission through interacting mesoscopic systems: This is a review of the phase coherent transmission through interacting\nmesoscopic conductors. As a paradigm we study the transmission amplitude and\nthe dephasing rate for electron transport through a quantum dot in the Coulomb\nblockade regime. We summarize experimental and theoretical work devoted to the\nphase of the transmission amplitude. It is shown that the evolution of the\ntransmission phase may be dominated by non-universal features in the short-time\ndynamics of the quantum dot. The controlled dephasing in Coulomb coupled\nconductors is investigated. Examples comprise a single or multiple quantum dots\nin close vicinity to a quantum point contact. The current through the quantum\npoint contact \"measures\" the state of the dots and causes dephasing. The\ndephasing rate is derived using widely different theoretical approaches. The\nCoulomb coupling between mesoscopic conductors may prove useful for future work\non electron coherence and quantum computing.",
        "positive": "Unusual magnetotransport and anomalous Hall effect in\n  quasi-two-dimensional van der Waals ferromagnet Fe$_4$GeTe$_2$: Fe$_4$GeTe$_2$, an itinerant vdW ferromagnet (FM) having Curie temperature\n(T$_C$) close to room temperature ($\\sim 270$ K), exhibits another transition\n(T$_{SR}$ $\\sim$ 120 K) where the easy axis of magnetization changes from\nin-plane to the out-of-plane direction in addition to T$_C$. Here, we have\nstudied the magnetotransport in a multilayer Hall bar device fabricated on 300\nnm Si/SiO$_2$ substrate. Interestingly, the zero field resistivity shows a\nnegligible change in resistivity near T$_C$ unlike the typical metallic FM,\nwhereas, it exhibits a dramatic fall below T$_{SR}$. Also, the resistivity\nshows a weak anomaly at T $ \\sim $ 38 K (T$_Q$), below which the resistivity\nshows a quadratic temperature dependence according to the Fermi liquid\nbehavior. Temperature-dependent Hall data exhibits important consequences. The\nordinary Hall coefficient changes sign near T$_{SR}$ indicating the change in\nmajority carriers. In a similar manner, the magnetoresistance (MR) data shows\nsignificantly large negative MR near T$_{SR}$ and becomes positive below T$_Q$.\nThe observations of anomaly in the resistivity, sign-change of the ordinary\nHall coefficient and maximum negative MR near T$_{SR}$, together suggest a\npossible Fermi surface reconstruction associated with the spin reorientation\ntransition. Furthermore, analysis of the Hall data reveals a significant\nanomalous Hall conductivity (AHC) from $\\sim 123 \\Omega^{-1}$ cm$^{-1}$ (at T\n$\\approx$ 5 K) to the maximum value of $\\sim 366 \\Omega^{-1}$ cm$^{-1}$ near\nT$_{SR}$. While the low-temperature part may originate due to the intrinsic KL\nmechanism, our analysis indicates that the temperature-dependent AHC is\nprimarily appearing due to the side-jump mechanism as a result of the spin-flip\nelectron-magnon scattering. Our study demonstrates an interplay between\nmagnetism and band topology and its consequence on electron transport in\nFe$_4$GeTe$_2$."
    },
    {
        "anchor": "Renormalization of single-ion magnetic anisotropy in the absence of\n  Kondo effect: Inelastic spin flip excitations associated with single-ion magnetic\nanisotropy of quantum spins, can be strongly renormalized by Kondo exchange\ncoupling to the conduction electrons in the substrate, as shown recently for\nthe case of Co adatoms on CuN$_2$ islands. In this case differential\nconductance spectra show zero-bias anomalies due to a Kondo effect of the\ndoubly degenerate ground state, and finite-bias step features due to spin flip\nexcitations. Here I consider spin-1 quantum magnets with positive uniaxial\nanisotropy, where the ground state is non-degenerate and hence the Kondo effect\ndoes not take place. Nevertheless the renormalization of inelastic spin\nexcitations due to exchange coupling by hybridization of the quantum spin with\nthe conduction electrons still takes place despite the complete absence of the\nKondo effect in the ground state. Additionally, I show that away from\nparticle-hole symmetry, charge fluctuations have a similar effect to Kondo\nexchange coupling, leading to the renormalization of spin flip excitations.\nHowever, in contrast to the renormalization by Kondo exchange, charge\nfluctuations lead to asymmetric spectra, which for strong charge fluctuations\ncan mimic Fano behavior.",
        "positive": "On dielectric screening in twisted double bilayer graphene: We have studied the dielectric screening of electric field which is induced\nby a gate voltage in twisted double bilayer graphene by using a sample with a\nmismatch angle of about 5 degrees. In low temperature magnetotransport\nmeasurements, quantum oscillations of magnetoresistance originating from two\nbands with different carrier density were observed. The behavior of the carrier\ndensities with respect to the total carrier density were distinct from that of\nthe AB-stacked tetralayer graphene. The carrier density ratio was theoretically\nanalyzed in terms of the model that the induced charge decays exponentially\nwith distance with a screening length {\\lambda}. The estimated {\\lambda} was\nslightly larger than that of AB-stacked graphene, which would possibly reflect\nthe difference in the inter-plane distribution of probability of the wave\nfunction."
    },
    {
        "anchor": "Quasi-bound states of Schrodinger and Dirac electrons in magnetic\n  quantum dot: The properties of a two-dimensional electron are investigated in the presence\nof a circular step magnetic field profile. Both electrons with parabolic\ndispersion as well as Dirac electrons with linear dispersion are studied. We\nfound that in such a magnetic quantum dot no electrons can be confined.\nNevertheless close to the Landau levels quasi-bound states can exist with a\nrather long life time.",
        "positive": "Spectral analysis of non-equilibrium molecular dynamics: spectral phonon\n  temperature and phonon local non-equilibrium in thin films and across\n  interfaces: Although extensive experimental and theoretical works have been conducted to\nunderstand the ballistic and diffusive phonon transport in nanomaterials\nrecently, direct observation of temperature and thermal nonequilibrium of\ndifferent phonon modes has not been realized. Herein, we have developed a\nmethod within the framework of molecular dynamics to calculate the temperatures\nof phonon in both real and phase spaces. Taking silicon thin film and graphene\nas examples, we directly obtained the spectral phonon temperature (SPT) and\nobserved the local thermal nonequilibrium between the ballistic and diffusive\nphonons. Such nonequilibrium also generally exists across interfaces and is\nsurprisingly large, and it provides an additional thermal interfacial\nresistance mechanism. Our SPT results directly show that the vertical thermal\ntransport across the dimensionally mismatched graphene/substrate interface is\nthrough the coupling between flexural acoustic phonons of graphene and the\nlongitudinal phonons in the substrate with mode conversion. In the\ndimensionally matched interfaces, e.g. graphene/graphene junction and\ngraphene/boron nitride planar interfaces, strong coupling occurs between the\nacoustic phonon modes on both sides, and the coupling decreases with\ninterfacial mixing. The SPT method together with the spectral heat flux can\neliminate the size effect of the thermal conductivity prediction induced from\nballistic transport. Our work shows that in thin films and across interfaces,\nphonons are in local thermal nonequilibrium."
    },
    {
        "anchor": "Local Semiconducting Transition in Armchair Carbon Nanotubes: The Effect\n  of Periodic Bi-site Perturbation on Electronic and Transport Properties of\n  Carbon Nanotubes: In carbon nanotubes, the most abundant defects, caused for example by\nirradiation or chemisorption treatments, are small perturbing clusters, i.e.\nbi-site defects, extending over both A and B sites. The relative positions of\nthese perturbing clusters play a crucial role in determining the electronic\nproperties of carbon nanotubes. Using bandstructure and electronic transport\ncalculations, we find out that in the case of armchair metallic nanotubes a\nband gap opens up when the clusters fulfill a certain periodicity condition.\nThis phenomenon might be used in future nanoelectronic devices in which certain\nregions of single metallic nanotubes could be turned to semiconducting ones.\nAlthough in this work we study specifically the effect of hydrogen adatom\nclusters, the phenomenon is general for different types of defects. Moreover,\nwe study the influence of the length and randomness of the defected region on\nthe electron transport through it.",
        "positive": "Anomalous Josephson Hall effect in magnet/triplet superconductor\n  junctions: We investigate anomalous Hall effect in a magnet coupled to a triplet\nsuperconductor under phase gradient. It is found that the anomalous Hall\nsupercurrent arises from non-trivial structure of the magnetization. The\nmagnetic structure manifested in the Hall supercurrent is characterized by even\norder terms of the exchange coupling, essentially different from that discussed\nin the context of anomalous Hall effect, reflecting the disspationless nature\nof supercurrent. We also discuss a possible candidate for magnetic structure to\nverify our prediction."
    },
    {
        "anchor": "Entanglement from Charge Statistics: Exact Relations for Many-Body\n  Systems: We present exact formulas for the entanglement and R\\'{e}nyi entropies\ngenerated at a quantum point contact (QPC) in terms of the statistics of charge\nfluctuations, which we illustrate with examples from both equilibrium and\nnon-equilibrium transport. The formulas are also applicable to groundstate\nentanglement in systems described by non-interacting fermions in any dimension,\nwhich in one dimension includes the critical spin-1/2 XX and Ising models where\nconformal field theory predictions for the entanglement and R\\'{e}nyi entropies\nare reproduced from the full counting statistics. These results may play a\ncrucial role in the experimental detection of many-body entanglement in\nmesoscopic structures and cold atoms in optical lattices.",
        "positive": "Comment on \"Advanced field emission measurement techniques for research\n  on modern cold cathode materials and their applications for transmission-type\n  x-ray sources\" [Rev. Sci. Instrum. 91, 083906 (2020)]: This Comment suggests that technological field electron emission (FE) papers,\nsuch as the paper under discussion [P. Serbun et al.,, Rev. Sci. Instrum. 91,\n083906 (2020)], should use FE theory based on the 1956 work of Murphy and Good\n(MG), rather than a simplified version of FE theory based on the original 1928\nwork of Fowler and Nordheim (FN). Use of the 1928 theory is common practice in\ntechnological FE literature, but the MG treatment is known to be better physics\nthan the FN treatment, which contains identifiable errors. The MG treatment\npredicts significantly higher emission current densities and currents for\nemitters than does the FN treatment. From the viewpoint of the research and\ndevelopment of electron sources, it is counterproductive (and unhelpful for\nnon-experts) for the technological FE literature to use theory that undervalues\nthe performance of field electron emitters."
    },
    {
        "anchor": "Magnetic Scanning Tunneling Microscopy with a Two-Terminal Non-Magnetic\n  Tip: Quantitative Results: We report numerical simulation result of a recently proposed \\{P. Bruno,\nPhys. Rev. Lett {\\bf 79}, 4593, (1997)\\} approach to perform magnetic scanning\ntunneling microscopy with a two terminal non-magnetic tip. It is based upon the\nspin asymmetry effect of the tunneling current between a ferromagnetic surface\nand a two-terminal non-magnetic tip. The spin asymmetry effect is due to the\nspin-orbit scattering in the tip. The effect can be viewed as a Mott scattering\nof tunneling electrons within the tip. To obtain quantitative results we\nperform numerical simulation within the single band tight binding model, using\nrecursive Green function method and Landauer-B\\\"uttiker formula for\nconductance. A new model has been developed to take into account the spin-orbit\nscattering off the impurities within the single-band tight-binding model. We\nshow that the spin-asymmetry effect is most prominent when the device is in\nquasi-ballistic regime and the typical value of spin asymmetry is about 5%.",
        "positive": "Universal Scaling Laws in Schottky Heterostructures Based on\n  Two-Dimensional Materials: We identify a new universality in the carrier transport of\ntwo-dimensional(2D)-material-based Schottky heterostructures. We show that the\nreversed saturation current ($\\mathcal{J}$) scales universally with temperature\n($T$) as $ \\log(\\mathcal{J}/T^{\\beta}) \\propto -1/T$, with $\\beta = 3/2$ for\nlateral Schottky heterostructures and $\\beta = 1$ for vertical Schottky\nheterostructures, over a wide range of 2D systems including nonrelativistic\nelectron gas, Rashba spintronic system, single and few-layer graphene,\ntransition metal dichalcogenides and thin-films of topological solids. Such\nuniversalities originate from the strong coupling between the thermionic\nprocess and the in-plane carrier dynamics. Our model resolves some of the\nconflicting results from prior works and is in agreement with recent\nexperiments. The universal scaling laws signal the breakdown of $\\beta=2$\nscaling in the classic diode equation widely-used over the past 60 years. Our\nfindings shall provide a simple analytical scaling for the extraction of the\nSchottky barrier height in 2D-material-based heterostructure, thus paving way\nfor both fundamental understanding of nanoscale interface physics and applied\ndevice engineering."
    },
    {
        "anchor": "Dynamically-generated pure spin current in single-layer graphene: The conductance mismatch problem limits the spin-injection efficiency\nsignificantly, and spin-injection into graphene has been usually requiring\nhigh-quality tunnel barriers to circumvent the conductance mismatch. We\nintroduce a novel approach, which enables generation of a pure spin current\ninto single-layer graphene (SLG) free from electrical conductance mismatch by\nusing dynamical spin injection. Experimental demonstration of\nspin-pumping-induced spin current generation and spin transport in SLG at room\ntemperature was successfully achieved and the spin coherence was estimated to\nbe 1.36 {\\mu}m by using a conventional theoretical model based on\nLandau-Lifshitz-Gilbert equation. The spin coherence is proportional to the\nquality of SLG, which indicates that spin relaxation in SLG is governed by the\nElliot-Yafet mechanism as was reported.",
        "positive": "Defect Induced Photoluminescence from Dark Excitonic States in\n  Individual Single-Walled Carbon Nanotubes: We show that new low-energy photoluminescence (PL) bands can be created in\nsemiconducting single-walled carbon nanotubes by intense pulsed excitation. The\nnew bands are attributed to PL from different nominally dark excitons that are\n\"brightened\" due to defect-induced mixing of states with different parity\nand/or spin. Time-resolved PL studies on single nanotubes reveal a significant\nreduction of the bright exciton lifetime upon brightening of the dark excitons.\nThe lowest energy dark state has longer lifetimes and is not in thermal\nequilibrium with the bright state."
    },
    {
        "anchor": "Topological proximity effects in a Haldane-graphene bilayer system: We reveal a proximity effect between a topological band (Chern) insulator\ndescribed by a Haldane model and spin-polarized Dirac particles of a graphene\nlayer. Coupling weakly the two systems through a tunneling term in the bulk,\nthe topological Chern insulator induces a gap and an opposite Chern number on\nthe Dirac particles at half-filling resulting in a sign flip of the Berry\ncurvature at one Dirac point. We study different aspects of the bulk-edge\ncorrespondence and present protocols to observe the evolution of the Berry\ncurvature as well as two counter-propagating (protected) edge modes with\ndifferent velocities. In the strong-coupling limit, the energy spectrum shows\nflat bands. Therefore we build a perturbation theory and address further the\nbulk-edge correspondence. We also show the occurrence of a topological\ninsulating phase with Chern number one when only the lowest band is filled. We\ngeneralize the effect to Haldane bilayer systems with asymmetric Semenoff\nmasses. We propose an alternative definition of the topological invariant on\nthe Bloch sphere.",
        "positive": "Spin-wave Resonance in Arrays of Nanoscale Synthetic-antiferromagnets: The study concerns dynamics of standing spin waves in arrays of sub-100 nm\nelliptic synthetic-antiferromagnet (SAF) nanodisks. We performed a detailed\nferromagnetic resonance analysis in conjunction with micromagnetic modeling to\nfind out several prominent traits of such systems. One broad line is shown to\nbe the sole resonant response for a SAF of the considered sizes. We demonstrate\nthat this mode is degenerated, and its excitation map resembles a superposition\nof in-center and edge-type oscillations. We also show how this hybrid\nexcitation leads to almost twofold enhancement in the shape-induced anisotropy\nof the mode."
    },
    {
        "anchor": "Singlet-Triplet Physics and Shell Filling in Carbon Nanotube Double\n  Quantum Dots: An artifcial two-atomic molecule, also called a double quantum dot (DQD), is\nan ideal system for exploring few electron physics. Spin-entanglement between\njust two electrons can be explored in such systems where singlet and triplet\nstates are accessible. These two spin-states can be regarded as the two states\nin a quantum two-state system, a so-called singlet-triplet qubit. A very\nattractive material for realizing spin based qubits is the carbon nanotube\n(CNT), because it is expected to have a very long spin coherence time. Here we\nshow the existence of a gate-tunable singlet-triplet qubit in a CNT DQD. We\nshow that the CNT DQD has clear shell structures of both four and eight\nelectrons, with the singlet-triplet qubit present in the four-electron shells.\nWe furthermore observe inelastic cotunneling via the singlet and triplet\nstates, which we use to probe the splitting between singlet and triplet, in\ngood agreement with theory.",
        "positive": "Chirality-Selective Transport of Benzene Molecules on Carbon Nanotubes: Using molecular dynamics simulations, we predict an effect of chirality on\nthe conduction of benzene molecules along the surface of carbon nanotubes\n(CNTs) subjected to a thermal gradient. The group drift velocity of the\nmolecules is found to be maximal in the case of an armchair CNT, and to\ndecrease with decreasing chiral angle. This chirality effect on thermodiffusion\nis induced by a variation in the optimized paths of molecules that change with\ndifferent electronic overlap at the interface. The mechanism for the\nthermophoretic transport is identified to be coupled with a gradient of\nadsorbate-substrate interaction energy, which originates from the anharmonic\nnature of the van der Waals potential."
    },
    {
        "anchor": "Nanoscale Charge Balancing Mechanism in Alkali Substituted\n  Calcium-Silicate-Hydrate Gels: Alkali-activated materials and related alternative cementitious systems are\nsustainable material technologies that have the potential to substantially\nlower CO$_2$ emissions associated with the construction industry. However, the\nimpact of augmenting the chemical composition of the material on the main\nbinder phase, calcium-silicate-hydrate gel, is far from understood,\nparticularly since this binder phase is disordered at the nanoscale. Here, we\nreveal the presence of a charge balancing mechanism at the molecular level,\nwhich leads to stable structures when alkalis (i.e., Na or K) are incorporated\ninto a calcium-silicate-hydrate gel, as modeled using crystalline 14{\\AA}\ntobermorite. These alkali containing charge balanced structures possess\nsuperior mechanical properties compared to their charge unbalanced\ncounterparts. Our results, which are based on first-principles simulations\nusing density functional theory, include the impact of charge balancing on the\noptimized geometries of the new model phases, formation energies, local bonding\nenvironments, bulk moduli and diffusion barriers of the alkali atoms within the\ncrystals.",
        "positive": "Origin of coherent G band phonon spectra in single wall carbon nanotubes: Coherent phonons in single wall carbon nanotubes (SWNTs) are observed as\noscillations of the differential absorption coefficient as a function of time\nby means of pump-probe spectroscopy. For the radial breathing mode (RBM) of a\nSWNT, the coherent phonon signal is understood to be a result of the modulated\ndiameter-dependent energy gaps due to the coherent RBM phonon oscillations.\nHowever, this mechanism might not be the dominant contribution to other phonon\nmodes in the SWNT. In particular, for the G band phonons, which correspond to\nbond-stretching motions, we find that the modulation of the interatomic dipole\nmatrix element gives rise to a strong coherent G band phonon intensity\ncomparable to the coherent RBM phonon intensity. We also further discuss the\ndependence of coherent G band and RBM phonon amplitudes on the laser excitation\npulse width."
    },
    {
        "anchor": "Excitons in hexagonal boron nitride single-layer: a new platform for\n  polaritonics in the ultraviolet: The electronic and optical properties of 2D hexagonal boron nitride are\nstudied using first principle calculations. GW and BSE methods are employed in\norder to predict with better accuracy the excited and excitonic properties of\nthis material. We determine the values of the band gap, optical gap, excitonic\nbinding energies and analyse the excitonic wave functions. We also calculate\nthe exciton energies following an equation of motion formalism and the Elliot\nformula, and find a very good agreement with the GW+BSE method. The optical\nproperties are studied for both the TM and TE modes, showing that 2D hBN is a\ngood candidate to polaritonics in the UV range. In particular it is shown that\na single layer of h-BN can act as an almost perfect mirror for ultraviolet\nelectromagnetic radiation.",
        "positive": "Energy Spectrum for Neutral Collective Excitations in Striped Hall\n  States: Neutral collective excitations in the striped Hall state are studied by using\nthe single mode approximation and Hartree-Fock approximation at the half-filled\nthird and fourth Landau level. We find that the spectrum includes anisotropic\nNG modes and periodic line nodes."
    },
    {
        "anchor": "Intrinsic Spin Hall Effect in s-wave Superconducting State: Analysis of\n  Rashba Model: A general expression for the spin Hall conductivity (SHC) in the s-wave\nsuperconducting state at finite temperatures is derived. Based on the\nexpression, we study the SHC in a two-dimensional electron gas model in the\npresence of Rashba spin-orbit interaction (SOI). The SHC is zero in the normal\nstate, whereas it takes a large negative value as soon as the superconductivity\noccurs, due to the change in the quasiparticle contributions. Since this\nremarkable behavior is independent of the strength of the SOI, it will be\nwidely observed in thin films of superconductors with surface-induced Rashba\nSOI, or in various non-centrosymmetric superconductors.",
        "positive": "Bistable Photon Emission from a Solid-State Single-Atom Laser: We predict a bistability in the photon emission from a solid-state\nsingle-atom laser comprising a microwave cavity coupled to a voltage-biased\ndouble quantum dot. To demonstrate that the single-atom laser is bistable, we\nevaluate the photon emission statistics and show that the distribution takes\nthe shape of a tilted ellipse. The switching rates of the bistability can be\nextracted from the electrical current and the shot noise in the quantum dots.\nThis provides a means to control the photon emission statistics by modulating\nthe electronic transport in the quantum dots. Our prediction is robust against\nmoderate electronic decoherence and dephasing and is important for current\nefforts to realize single-atom lasers with gate-defined quantum dots as the\ngain medium."
    },
    {
        "anchor": "Correlations and fluctuations of a confined electron gas: The grand potential $\\Omega$ and the response $R = - \\partial \\Omega\n/\\partial x$ of a phase-coherent confined noninteracting electron gas depend\nsensitively on chemical potential $\\mu$ or external parameter $x$. We compute\ntheir autocorrelation as a function of $\\mu$, $x$ and temperature. The result\nis related to the short-time dynamics of the corresponding classical system,\nimplying in general the absence of a universal regime. Chaotic, diffusive and\nintegrable motions are investigated, and illustrated numerically. The\nautocorrelation of the persistent current of a disordered mesoscopic ring is\nalso computed.",
        "positive": "Thermal generation of shift electric current: It is shown that the dissipation of energy in an electron gas confined in a\nquantum well made of non-centrosymmetric crystal leads to a direct electric\ncurrent. The current originates from the real-space shift of the wavepackets of\nBloch electrons at the electron scattering by phonons, which tends to restore\nthermal equilibrium between the electron and phonon subsystems. We develop a\nmicroscopic theory of such a phonogalvanic effect for narrow band gap\nzinc-blende quantum wells."
    },
    {
        "anchor": "Rashba spin-orbit interaction enhanced by graphene in-plane deformations: Graphene consists in a single-layer carbon crystal where 2$p_z$ electrons\ndisplay a linear dispersion relation in the vicinity of the Fermi level,\nconveniently described by a massless Dirac equation in $2+1$ spacetime.\nSpin-orbit effects open a gap in the band structure and offer perspectives for\nthe manipulation of the conducting electrons spin. Ways to manipulate\nspin-orbit couplings in graphene have been generally assessed by proximity\neffects to metals that do not compromise the mobility of the unperturbed system\nand are likely to induce strain in the graphene layer. In this work we explore\nthe $\\rm{U(1)}\\times SU(2)$ gauge fields that result from the uniform\nstretching of a graphene sheet under a perpendicular electric field.\nConsidering such deformations is particularly relevant due to the\ncounter-intuitive enhancement of the Rashba coupling between 30-50% for small\nbond deformations well known from tight-binding and DFT calculations. We report\nthe accessible changes that can be operated in the band structure in the\nvicinity of the K points as a function of the deformation strength and\ndirection.",
        "positive": "Topological D-Class Physics with Passive Acoustic Elements: In this work, we supply an engineering solution that paves the way to the\nimplementation of the full classification table of topological insulators with\npassive acoustic crystals. As an example, we design an acoustic crystal\ndisplaying the full range of characteristics of a topological insulator from\nclass D, such as non-trivial Chern numbers and an exact particle-hole symmetry\nfor both bulk and edge dynamics. The key is a particular geometry of the\nacoustic resonators that facilitates a large number of independent and\nequal-strength couplings, eight to be precise, such that the mode-coupling\ntheory remains accurate. The latter enables us to implement with high fidelity\nthe de-complexified tight-binding model generating the topological phases from\nclass D in 2-dimensions, previously announced in [Barlas et al, PRB (2018)].\nThe successful realization of a topological acoustic crystal from class D paves\nthe way to the observation of the Majorana-like modes stabilized by pi-fluxes."
    },
    {
        "anchor": "Two rods confined by positive plates: Effective forces and charge\n  distribution profiles: Monte Carlo simulations were employed to study two negative rods confined\nbetween two parallel plates. The system is immersed in a 1-1 restricted\nprimitive model electrolyte. Ion distributions and forces per unit of area\n(pressures) on rods and plates are accessed by sampling the NVT ensemble.\nPressures are analyzed by means of their corresponding electric and contact\n(depletion) contributions. This was done for several charge distributions on\nplates, plates charge densities, and plate-plate surface separation distances.\nWe found an enhancement of the inherent repulsive rod-rod effective force when\nuncharged plates are the confining species. On the contrary, a strong decrease\nof the rod-rod effective repulsion was obtained for positively charged plates.\nMoreover, attraction was also found for plates having a charge equal to that of\nfully charged bilipid bilayers. These results agree with DNA-phospholipid\ncomplexation experiments. On the other hand, for a model having the plates\ncharges fixed on a grid, very long range rod-rod sin-like effective forces were\nobtained. As explained in the text, they are a consequence of the rod-plate\ndouble layer coupling.",
        "positive": "Photoluminescence Spectra of Quantum Dots: Enhanced Efficiency of the\n  Electron-Phonon Interaction: A theory of photoluminescence in semiconductor quantum dots is developed\nwhich relies on two key ingredients. First, it takes into account\nnon-adiabaticity of the exciton-phonon system. Second, it includes the\nmultimode dielectric model of LO-phonons and of the electron-phonon interaction\nin confined systems. The role of non-adiabaticity is shown to be of paramount\nimportance in spherical quantum dots, where the lowest one-exciton state can be\ndegenerate or quasi-degenerate. For various quantum dot structures, the\ncalculated intensities of phonon satellites as a function of temperature,\nexcitation energy and size of quantum dots are in a fair agreement with\nexperimental data on photoluminescence."
    },
    {
        "anchor": "Fractional Quantum Hall Effect States as Exact Ground States: We construct many particle Hamiltonians for which the Laughlin and Jain\nwavefunctions are exact ground states. The Hamiltonians involve fermions in a\nmagnetic field and with inter-particle interactions. For the Laughlin\nwave-functions,the interactions involve two- and three-body correlations\nsimilar to the Chern-Simons interactions, whereas for the projected Jain\nwave-functions, N-body interactions (which cannot be explicitly written down in\ngeneral) are involved.",
        "positive": "Dephasing in quantum chaotic transport: a semiclassical approach: We investigate the effect of dephasing/decoherence on quantum transport\nthrough open chaotic ballistic conductors in the semiclassical limit of small\nFermi wavelength to system size ratio, $\\lambda_F/L << 1$. We use the\ntrajectory-based semiclassical theory to study a two-terminal chaotic dot with\ndecoherence originating from:\n  (i) an external closed quantum chaotic environment,\n  (ii) a classical source of noise,\n  (iii) a voltage probe, i.e. an additional current-conserving terminal.\n  We focus on the pure dephasing regime, where the coupling to the external\nsource of dephasing is so weak that it does not induce energy relaxation. In\naddition to the universal algebraic suppression of weak localization, we find\nan exponential suppression of weak-localization $\\propto\n\\exp[-\\tilde{\\tau}/\\tau_\\phi]$, with the dephasing rate $\\tau_\\phi^{-1}$. The\nparameter $\\tilde{\\tau}$ depends strongly on the source of dephasing. For a\nvoltage probe, $\\tilde{\\tau}$ is of order the Ehrenfest time $\\propto \\ln\n[L/\\lambda_F ]$. In contrast, for a chaotic environment or a classical source\nof noise, it has the correlation length $\\xi$ of the coupling/noise potential\nreplacing the Fermi wavelength $\\lambda_F $. We explicitly show that the Fano\nfactor for shot noise is unaffected by decoherence. We connect these results to\nearlier works on dephasing due to electron-electron interactions, and\nnumerically confirm our findings."
    },
    {
        "anchor": "Zero-bias tunneling anomaly in a clean 2D electron gas caused by smooth\n  density variations: We show that smooth variations, \\delta n({\\bf r}), of the local electron\nconcentration in a clean 2D electron gas give rise to a zero-bias anomaly in\nthe tunnel density of states, \\nu(\\omega), even in the absence of scatterers,\nand thus, without the Friedel oscillations. The energy width, \\omega_0, of the\nanomaly scales with the magnitude, \\delta n, and characteristic spatial extent,\nD, of the fluctuations as (\\delta n/D)^{2/3}, while the relative magnitude\n\\delta\\nu/\\nu scales as (\\delta n/D). With increasing \\omega, the averaged\n\\delta\\nu oscillates with \\omega. We demonstrate that the origin of the anomaly\nis a weak curving of the classical electron trajectories due to the smooth\ninhomogeneity of the gas. This curving suppresses the corrections to the\nelectron self-energy which come from the virtual processes involving two\nelectron-hole pairs",
        "positive": "Microwave-driven coherent operations of a semiconductor quantum dot\n  charge qubit: A most intuitive realization of a qubit is a single electron charge sitting\nat two well-defined positions, such as the left and right sides of a double\nquantum dot. This qubit is not just simple but also has the potential for\nhigh-speed operation, because of the strong coupling of electric fields to the\nelectron. However, charge noise also couples strongly to this qubit, resulting\nin rapid dephasing at nearly all operating points, with the exception of one\nspecial 'sweet spot'. Fast dc voltage pulses have been used to manipulate\nsemiconductor charge qubits, but these previous experiments did not achieve\nhigh-fidelity control, because dc gating requires excursions away from the\nsweet spot. Here, by using resonant ac microwave driving, we achieve coherent\nmanipulation of a semiconductor charge qubit, demonstrating a Rabi frequency of\nup to 2GHz, a value approaching the intrinsic qubit frequency of 4.5GHz. Z-axis\nrotations of the qubit are well-protected at the sweet spot, and by using ac\ngating, we demonstrate the same protection for rotations about arbitrary axes\nin the X-Y plane of the qubit Bloch sphere. We characterize operations on the\nqubit using two independent tomographic approaches: standard process tomography\nand a newly developed method known as gate set tomography. Both approaches show\nthat this qubit can be operated with process fidelities greater than 86% with\nrespect to a universal set of unitary single-qubit operations."
    },
    {
        "anchor": "Large out-of-plane spin-orbit torque in topological Weyl semimetal\n  candidate TaIrTe4: Topological quantum materials, with novel spin textures and broken crystal\nsymmetries are suitable candidates for spintronic memory technologies. Their\nunique electronic properties, such as protected surface states and exotic\nquasiparticles, can provide an out-of-plane spin polarized current needed for\nexternal field free magnetization switching of magnets with perpendicular\nmagnetic anisotropy. Conventional spin-orbit torque materials, such as heavy\nmetals and topological insulators, provide only an in-plane spin polarized\ncurrent, and recently explored materials with lower crystal symmetries provide\nvery low out-of-plane spin polarized current components, which is not suitable\nfor energy-efficient spin-orbit torque (SOT) applications. Here, we demonstrate\na large out-of-plane damping-like SOT at room temperature using a topological\nWeyl semimetal candidate TaIrTe4 with a lower crystal symmetry. We performed\nspin-orbit torque ferromagnetic resonance (STFMR) experiments in a\nTaIrTe4/Ni80Fe20 heterostructure and observed a large out-of-plane damping-like\nSOT efficiency. The out-of-plane spin Hall conductivity is estimated to be an\norder of magnitude higher than the reported values in other materials. These\nfindings of high spin Hall conductivity and large out-of-plane SOT efficiency\nare suitable for the development of energy efficient and external field-free\nspintronic devices.",
        "positive": "Coupling and Guided Propagation along Parallel Chains of Plasmonic\n  Nanoparticles: Here, extending our previous work on this topic, we derive a dynamic\nclosed-form dispersion relation for a rigorous analysis of guided wave\npropagation along coupled parallel linear arrays of plasmonic nanoparticles,\noperating as optical 'two-line' waveguides. Compared to linear arrays of\nnanoparticles, our results suggest that these waveguides may support longer\npropagation lengths and more confined beams, operating analogously to\ntransmission-line segments at lower frequencies. Our formulation fully takes\ninto account the whole dynamic interaction among the infinite number of\nnanoparticles composing the parallel arrays, considering also realistic\npresence of losses and the frequency dispersion of the involved plasmonic\nmaterials, providing further physical insights into the guidance properties\nthat characterize this geometry."
    },
    {
        "anchor": "Prediction of Giant Electro-actuation for Carbon Nanoscrolls: We study by first-principles calculations the electro-mechanical response of\ncarbon nanoscrolls. We show that although they present a very similar behavior\nto carbon nanotubes for what concerns the axial deformation sensitivity, they\nexhibit a radial response upon charge injection which is up to one order of\nmagnitude larger. In association with their high stability, this behavior make\nthem a natural choice for a new class of very efficient nano-actuators.",
        "positive": "Application of retardation-modulation polarimetry in studies of\n  nanocomposite materials: We demonstrate an application of retardation-modulation polarimetry in\nstudies of nanocomposite materials. Molecular ordering is explored on both\nnonchiral and chiral liquid crystals (LCs) in the bulk state and embedded into\nparallel-arrays of cylindrical channels of alumina or silica membranes of\ndifferent channel sizes (12-42 nm). Two arms polarimetry serves for\nsimultaneous measurements of the birefringence retardation and optical activity\ncharacterizing, respectively, orientational molecular ordering and chiral\nstructuring inside nanochannels."
    },
    {
        "anchor": "Electron-phonon bound state in graphene: The fine structure of the Dirac energy spectrum in graphene induced by\nelectron-optical phonon coupling is investigated in the portion of the spectrum\nnear the phonon emission threshold. The derived new dispersion equation in the\nimmediate neighborhood below the phonon threshold corresponds to an\nelectron-phonon bound state. We find that the singular vertex corrections\nbeyond perturbation theory increase strongly the electron-phonon binding\nenergy. The predicted enhancement of the effective electron-phonon coupling can\nbe measured using angle-resolved spectroscopy.",
        "positive": "Magnetic wallpaper Dirac fermions and topological magnetic Dirac\n  insulators: Topological crystalline insulators (TCIs) can host anomalous surface states\nwhich inherits the characteristics of crystalline symmetry that protects the\nbulk topology. Especially, the diversity of magnetic crystalline symmetries\nindicates the potential for novel magnetic TCIs with distinct surface\ncharacteristics. Here, we propose a topological magnetic Dirac insulator\n(TMDI), whose two-dimensional surface hosts fourfold-degenerate Dirac fermions\nprotected by either the $p'_c4mm$ or $p4'g'm$ magnetic wallpaper group. The\nbulk topology of TMDIs is protected by diagonal mirror symmetries, which give\nchiral dispersion of surface Dirac fermions and mirror-protected hinge modes.\nWe propose candidate materials for TMDIs including Nd$_4$Te$_8$Cl$_4$O$_{20}$\nand DyB$_4$ based on first-principles calculations, and construct a general\nscheme for searching TMDIs using the space group of paramagnetic parent states.\nOur theoretical discovery of TMDIs will facilitate future research on magnetic\nTCIs and illustrate a distinct way to achieve anomalous surface states in\nmagnetic crystals."
    },
    {
        "anchor": "Reversible vs. irreversible voltage manipulation of interfacial magnetic\n  anisotropy in Pt/Co/oxide multilayers: The perpendicular magnetic anisotropy at the Co/oxide interface in Pt/Co/MOx\n(MOx = MgOx, AlOx, TbOx) was modified by an electric field using a 10 nm-thick\nZrO2 as a solid electrolyte. The large voltage-driven modification of\ninterfacial magnetic anisotropy and the non-volatility of the effect is\nexplained in terms of the migration of oxygen ions towards/away from the Co/MOx\ninterface. While the effect is reversible in Pt/Co/AlOx and Pt/Co/TbOx, where\nthe Co layer can be oxidised or reduced, in Pt/Co/MgOx the effect has been\nfound to be irreversible. We propose that these differences may be related to\nthe different nature of the ionic conduction within the MOx layers.",
        "positive": "Topological Imbert-Fedorov shift in Weyl semimetals: The Goos-H\\\"anchen (GH) shift and the Imbert-Fedorov (IF) shift are optical\nphenomena which describe the longitudinal and transverse lateral shifts at the\nreflection interface, respectively. Here, we report the GH and IF shifts in\nWeyl semimetals (WSMs) - a promising material harboring low energy Weyl\nfermions, a massless fermionic cousin of photons. Our results show that GH\nshift in WSMs is valley-independent which is analogous to that discovered in a\n2D relativistic material - graphene. However, the IF shift has never been\nexplored in non-optical systems, and here we show that it is valley-dependent.\nFurthermore, we find that the IF shift actually originates from the topological\neffect of the system. Experimentally, the topological IF shift can be utilized\nto characterize the Weyl semimetals, design valleytronic devices of high\nefficiency, and measure the Berry curvature."
    },
    {
        "anchor": "Anisotropic Penetration Depths of Corner States in a Higher-Order\n  Topological Insulator: Higher-order topological insulators in two dimensions have states that\nlocalize at their corners, called corner states. In this paper, we reveal\ncharacteristics of the penetration depth of their corner states by using the\nBenalcazar-Bernevig-Hughes model. First, we show that when we change the energy\nof the corner states toward the end of the edge gap by adding an on-site\npotential to the corner site, the penetration depth along the edge diverges\ntoward infinity while the penetration depth into the bulk remaining finite. We\nanalytically derive the corner-state wavefunction in a form of elliptic\nintegrals, which reproduces this anisotropic behavior of corner states. This\nmeans that corner states have two kinds of penetration depths, and they behave\ndifferently. At last, we show that hybridizations between corner states are\ngoverned by the penetration depth through interference between the corner\nstates. It is because the corner states almost do not interfere with edge\nstates or bulk states.",
        "positive": "Transition from one- to two-mode generation regime in spin-torque\n  nano-oscillator mediated by thermal noise: Two-mode model of spin-torque nano-oscillator (STNO) under the action of\nthermal noise is considered. Langevin equations for mode amplitudes were\nderived starting from general nonlinear oscillator model. Stationary\nprobability distribution function describing mean mode generation powers was\nobtained using Fokker-Planck equation. It was shown that thermal noise can lead\nto two-mode generation in STNO. An increase of thermal noise power leads to\nexcitation of the second mode in a system and to a two-mode generation regime\nthrough intermediate state when two modes coexist only in some range of the\napplied currents."
    },
    {
        "anchor": "Eddy current interactions in a Ferromagnet-Normal metal bilayer\n  structure, and its impact on ferromagnetic resonance lineshapes: We investigate the effect of eddy currents on ferromagnetic resonance (FMR)\nin ferromagnet-normal metal (FM/NM) bilayer structures. Eddy-current effects\nare usually neglected for NM layer thicknesses below the microwave (MW) skin\ndepth (approx. 800 nm for Au at 10 GHz). However, we show that in much thinner\nNM layers (10-100 nm of Au or Cu) they induce a phase shift in the FMR\nexcitation when the MW driving field has a component perpendicular to the\nsample plane. This results in a strong asymmetry of the measured absorption\nlines. In contrast to typical eddy-current effects, the asymmetry is larger for\nthinner NM layers and is tunable through changing the sample geometry and the\nNM layer thickness.",
        "positive": "Counterpart of the Darrieus-Landau instability at a magnetic\n  deflagration front: The magnetic instability at the front of the spin avalanche in a crystal of\nmolecular magnets is considered. This phenomenon reveals similar features with\nthe Darrieus-Landau instability, inherent to classical combustion flame fronts.\nThe instability growth rate and the cut-off wavelength are investigated with\nrespect to the strength of the external magnetic field, both analytically in\nthe limit of an infinitely thin front and numerically for finite-width fronts.\nThe presence of quantum tunneling resonances is shown to increase the growth\nrate significantly, which may lead to a possible transition from deflagration\nto detonation regimes. Different orientations of the crystal easy axis are\nshown to exhibit opposite stability properties. In addition, we suggest\nexperimental conditions that could evidence the instability and its influence\non the magnetic deflagration velocity."
    },
    {
        "anchor": "$GW$ study of pressure-induced topological insulator transition in group\n  IV-tellurides: We calculate the electronic structure of the narrow gap semiconductors PbTe,\nSnTe and GeTe in the cubic phase using density functional theory (DFT) and the\n$G_0W_0$ method. Within DFT, we show that the band ordering obtained with a\nconventional semilocal exchange-correlation approximation is correct for SnTe\nand GeTe but wrong for PbTe. The correct band ordering at the high-symmetry\npoint L is recovered adding $G_0W_0$ quasiparticle corrections. However,\none-shot $G_0W_0$ produces artifacts in the band structure due to the wrong\norbital character of the DFT single-particle states at the band edges close to\nL. We show that in order to correct these artifacts it is enough to consider\nthe off-diagonal elements of the $G_0W_0$ self-energy corresponding to these\nstates. We also investigate the pressure dependence of the band gap for these\nmaterials and the possibility of a transition from a trivial to a non-trivial\ntopology of the band structure. For PbTe, we predict the band crossover and\ntopological transition to occur at around 4.8 GPa. For GeTe, we estimate the\ntopological transition to occur at 1.9 GPa in the constrained cubic phase, a\npressure lower than the one of the structural phase transition from rombohedral\nto cubic. SnTe is a crystalline topological insulator at ambient pressure, and\nthe transition into a trivial topology would take place under a volume\nexpansion of approximately $10\\%$.",
        "positive": "Trapping Surface Electrons on Graphene Layers and Islands: We report the use of time- and angle-resolved two-photon photoemission to map\nthe bound, unoccupied electronic structure of the weakly coupled\ngraphene/Ir(111) system. The energy, dispersion, and lifetime of the lowest\nthree image-potential states are measured. In addition, the weak interaction\nbetween Ir and graphene permits observation of resonant transitions from an\nunquenched Shockley-type surface state of the Ir substrate to graphene/Ir\nimage-potential states. The image-potential-state lifetimes are comparable to\nthose of mid-gap clean metal surfaces. Evidence of localization of the excited\nelectrons on single-atom-layer graphene islands is provided by\ncoverage-dependent measurements."
    },
    {
        "anchor": "Synchronization of many nano-mechanical resonators coupled via a common\n  cavity field: Using amplitude equations, we show that groups of identical nano-mechanical\nresonators, interacting with a common mode of a cavity microwave field,\nsynchronize to form a single mechanical mode which couples to the cavity with a\nstrength dependent on the square sum of the individual mechanical-microwave\ncouplings. Classically this system is dominated by periodic behaviour which,\nwhen analyzed using amplitude equations, can be shown to exhibit\nmulti-stability. In contrast groups of sufficiently dissimilar nano-mechanical\noscillators may lose synchronization and oscillate out of phase at\nsignificantly higher amplitudes. Further the method by which synchronization is\nlost resembles that for large amplitude forcing which is not of the Kuramoto\nform.",
        "positive": "Maxwell's demon in a double quantum dot with continuous charge detection: Converting information into work has during the last decade gained renewed\ninterest as it gives insight into the relation between information theory and\nthermodynamics. Here we theoretically investigate an implementation of\nMaxwell's demon in a double quantum dot and demonstrate how heat can be\nconverted into work using only information. This is accomplished by\ncontinuously monitoring the charge state of the quantum dots and transferring\nelectrons against a voltage bias using a feedback scheme. We investigate the\nelectrical work produced by the demon and find a non-Gaussian work\ndistribution. To illustrate the effect of a realistic charge detection scheme,\nwe develop a model taking into account noise as well as a finite delay time,\nand show that an experimental realization is feasible with present day\ntechnology. Depending on the accuracy of the measurement, the system is\noperated as an implementation of Maxwell's demon or a single-electron pump."
    },
    {
        "anchor": "Interfacial Properties of Monolayer and Bilayer MoS2 Contacts with\n  Metals: Beyond the Energy Band Calculations: Although many prototype devices based on two-dimensional (2D) MoS2 have been\nfabricated and wafer scale growth of 2D MoS2 has been realized, the fundamental\nnature of 2D MoS2-metal contacts has not been well understood yet. We provide a\ncomprehensive ab initio study of the interfacial properties of a series of\nmonolayer (ML) and bilayer (BL) MoS2-metal contacts (metal = Sc, Ti, Ag, Pt,\nNi, and Au). A comparison between the calculated and observed Schottky barrier\nheights (SBHs) suggests that many-electron effects are strongly suppressed in\nchannel 2D MoS2 due to a charge transfer. The extensively adopted energy band\ncalculation scheme fails to reproduce the observed SBHs in 2D MoS2-Sc\ninterface. By contrast, an ab initio quantum transport device simulation better\nreproduces the observed SBH in the two types of contacts and highlights the\nimportance of a higher level theoretical approach beyond the energy band\ncalculation in the interface study. BL MoS2-metal contacts have a reduced SBH\nthan ML MoS2-metal contacts due to the interlayer coupling and thus have a\nhigher electron injection efficiency.",
        "positive": "Time, momentum, and energy resolved pump-probe tunneling spectroscopy of\n  two-dimensional electron systems: Real-time probing of electrons can uncover intricate relaxation mechanisms\nand many-body interactions hidden in strongly correlated materials. While\nexperimenters have used ultrafast optical pump-probe methods in bulk materials,\nlaser heating and insensitivity below the surface prevent their application to\nencapsulated low-dimensional electron systems at millikelvin temperatures, home\nto numerous intriguing electronic phases. Here, we introduce time, momentum,\nand energy resolved pump-probe tunneling spectroscopy (Tr-MERTS). The method\nallows the injection of electrons at particular energies and observation of\ntheir subsequent decay in energy-momentum space. Using Tr-MERTS, we visualize\nelectronic decay processes in Landau levels with lifetimes up to tens of\nmicroseconds. Although most observed features agree with simple\nenergy-relaxation, we discover an unexpected splitting in the nonequilibrium\nenergy spectrum in the vicinity of a ferromagnetic state. An exact\ndiagonalization study of the system suggests that the splitting arises from a\nmaximally spin-polarized higher energy state, distinct from a conventional\nequilibrium skyrmion. Furthermore, we observe time-dependent relaxation of the\nsplitting, which we attribute to single-flipped spins forming topological spin\ntextures. These results establish Tr-MERTS as a powerful tool for studying the\ndynamics and properties of a two-dimensional electronic system beyond\nequilibrium."
    },
    {
        "anchor": "Plasmon mediated coherent population oscillations in molecular\n  aggregates: The strong coherent coupling of quantum emitters to vacuum fluctuations of\nthe light field offers opportunities for manipulating the optical and transport\nproperties of nanomaterials, with potential applications ranging from\nultrasensitive all-optical switching to creating polariton condensates. Often,\nubiquitous decoherence processes at ambient conditions limit these couplings to\nsuch short time scales that the quantum dynamics of the interacting system\nremains elusive. Prominent examples are strongly coupled exciton-plasmon\nsystems, which, so far, have mostly been investigated by linear optical\nspectroscopy. Here, we use ultrafast two-dimensional electronic spectroscopy to\nprobe the quantum dynamics of J-aggregate excitons collectively coupled to the\nspatially structured plasmonic fields of a gold nanoslit array. We observe rich\ncoherent Rabi oscillation dynamics reflecting a plasmon-driven coherent exciton\npopulation transfer over mesoscopic distances at room temperature. This opens\nup new opportunities to manipulate the coherent transport of matter excitations\nby coupling to vacuum fields.",
        "positive": "First-order effect of electron-electron interactions on the anomalous\n  Hall conductivity of massive Dirac fermions: We investigate the first-order correction to the anomalous Hall conductivity\nof 2D massive Dirac fermions arising from electron-electron interactions. In a\nfully gapped system in the limit of zero temperature, we find that this\ncorrection vanishes, confirming the absence of perturbative corrections to the\ntopological Hall conductivity. At finite temperature or chemical potential, we\nfind that the total Hall response decays faster than in the non-interacting\ncase, depending on the strength of electron-electron interactions. These\nfeatures, which could potentially be observed experimentally, show the\nimportance of two-body interactions for anomalous Hall transport."
    },
    {
        "anchor": "Wigner crystal in snaked nanochannels: We study properties of Wigner crystal in snaked nanochannels and show that\nthey are characterized by conducting sliding phase at low charge densities and\ninsulating pinned phase emerging above a certain critical charge density. The\ntransition between these phases has a devil's staircase structure typical for\nthe Aubry transition in dynamical maps and the Frenkel-Kontorova model. We\ndiscuss implications of this phenomenon for charge density waves in\nquasi-one-dimensional organic conductors and for supercapacitors in nanopore\nmaterials.",
        "positive": "Crossover from mesoscopic to universal phase for electron transmission\n  in quantum dots: Measuring phase in coherent electron systems (mesoscopic systems) provides\nample information not easily revealed by conductance measurements. Phase\nmeasurements in relatively large quantum dots (QDs) recently demonstrated a\nuniversal like phase evolution independent of dot size, shape, and occupancy.\nExplicitly, in Coulomb blockaded QDs the transmission phase increased\nmonotonically by pi throughout each conductance peak, thereafter, in the\nconductance valleys the phase returned sharply to its base value. Expected\nmesoscopic features in the phase, related to spin degeneracy or to exchange\neffects, were never observed. Presently, there is no satisfactory full\nexplanation for the observed phase universality. Unfortunately, the phase in a\nfew-electron QDs, where it can be better understood was never measured. Here we\nreport on such measurements on a small QD that occupy only 1-20 electrons. Such\ndot was embedded in one arm of a two path electron interferometer, with an\nelectron counter near the dot. Unlike the repetitive behavior found in larger\ndots we found now mesoscopic features for dot occupation of less than some 10\nelectrons. An unexpected feature in this regime is a clear observation of the\noccupation of two different orbital states by the first two electrons -\ncontrary to the recent publications. As the occupation increased the phase\nevolved and turned universal like for some 14 electrons and higher. The present\nmeasurements allowed us to determine level occupancy and parity. More\nimportantly, they suggest that QDs go through a phase transition, from\nmesoscopic to universal like behavior, as the occupancy increases. These\nmeasurements help in singling out potential few theoretical models among the\nmany proposed."
    },
    {
        "anchor": "Controlling thermal conductance using three-dimensional phononic\n  crystals: Controlling thermal transport at the nanoscale is vital for many\napplications. Previously, it has been shown that this control can be achieved\nwith periodically nanostructured two-dimensional phononic crystals, for the\ncase of suspended devices. Here we show that thermal conductance can also be\ncontrolled with three-dimensional phononic crystals, allowing the engineering\nof the thermal contact of more varied devices without the need of suspension in\nthe future. We show experimental results measured at sub-Kelvin temperatures\nfor two different period three-dimensional crystals, as well as for a bulk\ncontrol structure. The results show that the conductance can be enhanced with\nthe phononic crystal structures in our geometry. This result cannot be fully\nexplained by the simplest theory taking into account the coherent modification\nof the phonon band structure, calculated with finite element method\nsimulations.",
        "positive": "Towards quantized current arbitrary waveform synthesis: The generation of ac modulated quantized current waveforms using a\nsemiconductor non-adiabatic single electron pump is demonstrated. In standard\noperation the single electron pump generates a quantized output current of I =\nef where e is the charge of the electron and f is the pumping frequency.\nSuitable frequency modulation of f allows the generation of ac modulated output\ncurrents with different characteristics. By sinusoidal and saw tooth like\nmodulation of f accordingly modulated quantized current waveforms with kHz\nmodulation frequencies and peak currents up to 100 pA are obtained. Such ac\nquantized current sources could find applications ranging from precision ac\nmetrology to on-chip signal generation."
    },
    {
        "anchor": "Temperature dependent nonlinear Hall effect in macroscopic Si-MOS\n  antidot array: By measuring magnetoresistance and Hall effect in classically moderate\nperpendicular magnetic field in Si-MOSFET-type macroscopic antidot array we\nfound a novel effect: nonlinear with field, temperature- and density-dependent\nHall resistivity. We discuss qualitative explanation of the phenomenon and\nsuggest that it might originate from strong temperature dependence of the\nresistivity and mobility in the shells of the antidots.",
        "positive": "Row coupling in an interacting quasi-one-dimensional quantum wire\n  investigated using transport measurements: We study electron transport in quasi-one-dimensional wires at relatively weak\nelectrostatic confinements, where the Coulomb interaction distorts the ground\nstate, leading to the bifurcation of the electronic system into two rows.\nEvidence of finite coupling between the rows, resulting in bonding and\nantibonding states, is observed. At high dc source-drain bias, a structure is\nobserved at 0.5(2e^2/h) due to parallel double-row transport, along with a\nstructure at 0.25(2e^2/h), providing further evidence of coupling between the\ntwo rows."
    },
    {
        "anchor": "Tunneling conductance due to discrete spectrum of Andreev states: We study tunneling spectroscopy of discrete subgap Andreev states in a\nsuperconducting system. If the tunneling coupling is weak, individual levels\nare resolved and the conductance $G(V)$ at small temperatures is composed of a\nset of resonant Lorentz peaks which cannot be described within perturbation\ntheory over tunnelling strength. We establish a general formula for their\nwidths and heights and show that the width of any peak scales as normal-state\ntunnel conductance, while its height is $\\lesssim 2e^2/h$ and depends only on\ncontact geometry and the spatial profile of the resonant Andreev level. We also\nestablish an exact formula for the single-channel conductance that takes the\nwhole Andreev spectrum into account. We use it to study the interference of\nAndreev reflection processes through different levels. The effect is most\npronounced at low voltages, where an Andreev level at $E_j$ and its conjugate\nat $-E_j$ interfere destructively. This interference leads to the quantization\nof the zero-bias conductance: G(0) equals $2e^2/h$ (or 0) if there is (there is\nnot) a Majorana fermion in the spectrum, in agreement with previous results\nfrom $S$-matrix theory. We also study $G(eV>0)$ for a system with a pair of\nalmost decoupled Majorana fermions with splitting $E_0$ and show that at lowest\n$E_0$ there is a zero-bias Lorentz peak of width $W$ as expected for a single\nMajorana fermion (a topological NS-junction) with a narrow dip of width\n$E_0^2/W$ at zero bias, which ensures $G(0)=0$ (the NS-junction remains trivial\non a very small energy scale). As the coupling $W$ gets stronger, the dip\nbecomes narrower, which can be understood as enhanced decoupling of the remote\nMajorana fermion. Then the zero-bias dip requires extremely low temperatures\n$T\\lesssim E_0^2/W$ to be observed.",
        "positive": "Zero-bias photodetection in 2d materials via geometric design of\n  contacts: Structural or crystal asymmetry are necessary conditions for emergence of\nzero-bias photocurrent in light detectors. Structural asymmetry has been\ntypically achieved via $p-n$ doping being a technologically complex process.\nHere, we propose an alternative approach to achieve zero-bias photocurrent in\n2d material flakes exploiting the geometrical non-equivalence of source and\ndrain contacts. As a prototypical example, we equip a square-shaped flake of\nPdSe$_2$ with mutually orthogonal metal leads. Upon uniform illumination with\nlinearly-polarized light, the device demonstrates non-zero photocurrent which\nflips its sign upon 90$^\\circ$ polarization rotation. The origin of zero-bias\nphotocurrent lies in polarization-dependent lightning-rod effect. It enhances\nthe electromagnetic field at one contact from the orthogonal pair, and\nselectively activates the internal photoeffect at the respective metal-PdSe$_2$\nSchottky junction. The proposed technology of contact engineering can be\nextended to arbitrary 2d materials and detection of both polarized and natural\nlight."
    },
    {
        "anchor": "Suhl Instabilities in Nanoscopic Spheroids: We simulate the magnetization dynamics of a permalloy spheroid of nanoscopic\nsize in zero external field, such that both dipolar and exchange interactions\nare important. Low excitation power is used to obtain the frequencies and mode\npatterns of many normal modes. At higher power, non-linear three and four mode\ncouplings between magnons carrying orbital angular momentum are observed to\ngive rise to Suhl instabilities. Suhl's analysis of the selection rules\ngoverning the allowed processes is extended to initial states other than\nuniform precession. These rules are studied and confirmed by the simulations.\nBoth down- and up-conversion are seen as well as three and four-mode processes.\nGeneral trends are inferred for preferred instabilities among those that are\nallowed, although the thresholds for some instabilities appear to be very high.",
        "positive": "Anomalous hybridization of spectral winding topology in quantized\n  steady-state responses: Quantized response is one distinguishing feature of a topological system. In\nnon-Hermitian systems, the spectral winding topology yields quantized\nsteady-state response. By considering two weakly coupled non-Hermitian chains,\nwe discover that the spectral winding topology of one chain can be probed by a\nsteady-state response defined solely on the other chain, even when other\nimportant properties, e.g., {energetics} and entanglement entropy, indicate\nthat eigen-solutions are effectively {not hybridized} between the two chains.\nThis intriguing phenomenon, as carefully investigated in a large parameter\nspace with a varying system size, not only offers a new angle to understand\ninterchain signal propagation in a non-Hermitian setting but also reveals\nunexpected physics of spectral winding topology vs quantized response."
    },
    {
        "anchor": "Self-healing in unpassivated and passivated CdTe nanostructures:\n  structural stability and optical properties: We report the effects of passivation on the various properties like\nelectronic structure, structural stability and optical properties of CdTe in\nthe different nanostructure forms such as ultra-thin slabs, monolayers,\nnanorods and nanotubes. Further, based on these properties, the self-healing\nability of each nanostructure has been predicted. The optical properties\nsuggest that all of the passivated and specific unpassivated nanostructures are\nsuitable for optoelectronic applications. The 2D system in <110> orientation\nand nanotube derived from the <111> monolayer show significant self-healing in\nthe pristine structures.",
        "positive": "Persistent current induced by vacuum fluctuations in a quantum ring: We study theoretically interaction between electrons in a quantum ring\nembedded in a microcavity and vacuum fluctuations of electromagnetic field in\nthe cavity. It is shown that the vacuum fluctuations can split electron states\nof the ring with opposite angular momenta. As a consequence, the ground state\nof electron system in the quantum ring can be associated to nonzero electric\ncurrent. Since a ground-state current flows without dissipation, such a quantum\nring gets a magnetic moment and can be treated as an artificial spin."
    },
    {
        "anchor": "Coherent Transport in Y-Junction Graphene Waveguide: We performed a series of theoretical transport studies on Y-branch electron\nwaveguides which are embedded in mid-size armchair graphene nanoribbons\n(AGNRs). Non-equilibrium Greens function (NEGF) with different approximations\nof tight-binding (TB) Hamiltonian has been employed. Using the first nearest\nhopping approximation, we observed very pronounced conductance quantization,\nthe structure of which depends on geometrical design and shows a spacing of\n$4e^2/h$, indicating the existence of valley degree of freedom. Moreover, by\nincorporating the third nearest approximation, we observed seminal plateaus\ndeviated from multiples of $4e^2/h$ conductance, suggesting the lift of valley\ndegeneracy. Finally, Quasi-one dimensional band structure calculations have\nbeen performed to study the availability of energy channels and the role of the\nmajor geometrical parameters on the transport.",
        "positive": "Measurement-induced entanglement of two superconducting qubits: We study the problem of two superconducting quantum qubits coupled via a\nresonator. If only one quanta is present in the system and the number of\nphotons in the resonator is measured with a null result, the qubits end up in\nan entangled Bell state. Here we look at one source of errors in this quantum\nnondemolition scheme due to the presence of more than one quanta in the\nresonator, previous to the measurement. By analyzing the structure of the\nconditional Hamiltonian with arbitrary number of quanta, we show that the\nscheme is remarkably robust against these type of errors."
    },
    {
        "anchor": "Probing electron transport across a LSMO/Nb:STO heterointerface at the\n  nanoscale: We investigate electron transport across a complex oxide heterointerface of\nLa$_{0.67}$Sr$_{0.33}$MnO$_3$ (LSMO) on Nb:SrTiO$_3$ (Nb:STO) at different\ntemperatures. For this, we employ the conventional current-voltage method as\nwell as the technique of Ballistic Electron Emission Microscopy (BEEM), which\ncan probe lateral inhomogeneities in transport at the nanometer scale. From\ncurrent-voltage measurements, we find that the Schottky Barrier height (SBH) at\nthe LSMO/Nb:STO interface decreases at low temperatures accompanied by a larger\nthan unity ideality factor. This is ascribed to the tunneling dominated\ntransport caused by the narrowing of the depletion width at the interface.\nHowever, BEEM studies of such unbiased interfaces, do not exhibit SBH lowering\nat low temperatures, implying that this is triggered by the modification of the\ninterface due to an applied bias and is not an intrinsic property of the\ninterface. Interestingly, the SBH at the nanoscale, as extracted from BEEM\nstudies, at different locations in the device is found to be spatially\nhomogeneous and similar both at room temperature and at low temperatures. Our\nresults highlight the application of BEEM in characterizing electron transport\nand their homogeneity at such unbiased complex oxide interfaces and yields new\ninsights into the origin of the temperature dependence of the SBH at biased\ninterfaces.",
        "positive": "General corner charge formula in two-dimensional C_n-symmetric\n  higher-order topological insulators: In this paper, we derive a general formula for the quantized fractional\ncorner charge in two-dimensional C_n-symmetric higher-order topological\ninsulators. We assume that the electronic states can be described by the\nWannier functions and that the edges are charge neutral, but we do not assume\nvanishing bulk electric polarization. We expand the scope of the corner charge\nformula obtained in previous works by considering more general surface\nconditions, such as surfaces with higher Miller index and surfaces with surface\nreconstruction. Our theory is applicable even when the electronic states are\nlargely modulated near system boundaries. It also applies to insulators with\nnon-vanishing bulk polarization, and we find that in such cases the value of\nthe corner charge depends on the surface termination even for the same bulk\ncrystal with C_3 or C_4 symmetry, via a difference in the Wyckoff position of\nthe center of the C_n-symmetric crystal."
    },
    {
        "anchor": "Floquet topological phases with high Chern numbers in a periodically\n  driven extended Su-Schrieffer-Heeger model: The high Chern number phases with the Chern number |C| > 1 are observed in\nthis study of a periodically driven extended Su-Schrieffer-Heeger (E-SSH) model\nwith a cyclic parameter. Besides the standard intra-dimer and the\nnearest-neighbor (NN) inter-dimer hopping of the SSH model, an additional\nnext-nearest-neighbor (NNN) hopping is considered in the E-SSH model. The\ncyclic parameter, which plays the role of a synthetic dimension, is invoked as\na modulation of the hopping strengths. A rigorous analysis of different phase\ndiagrams has shown multiple Floquet topological phase transitions among the\nhigh Chern number phases. These phase transitions can be controlled by the\nstrength and frequency of the periodic driving. Instead of applying\nperturbation theory, the whole analysis is done by Floquet replica technique.\nThis gives a freedom to study high as well as low-frequency effects on the\nsystem by considering less or more number of photon sectors. This system can be\nexperimentally realized through a pulse sequence scheme in the optical lattice\nsetup.",
        "positive": "Magnetic bimerons as skyrmion analogues in in-plane magnets: A magnetic bimeron is a pair of two merons and can be understood as the\nin-plane magnetized version of a skyrmion. Here we theoretically predict the\nexistence of single magnetic bimerons as well as bimeron crystals, and compare\nthe emergent electrodynamics of bimerons with their skyrmion analogues. We show\nthat bimeron crystals can be stabilized in frustrated magnets and analyze what\ncrystal structure can stabilize bimerons or bimeron crystals via the\nDzyaloshinskii-Moriya interaction. We point out that bimeron crystals, in\ncontrast to skyrmion crystals, allow for the detection of a pure topological\nHall effect. By means of micromagnetic simulations, we show that bimerons can\nbe used as bits of information in in-plane magnetized racetrack devices, where\nthey allow for current-driven motion for torque orientations that leave\nskyrmions in out-of-plane magnets stationary."
    },
    {
        "anchor": "Reciprocal skin effect and its realization in a topolectrical circuit: A system is non-Hermitian when it exchanges energy with its environment and\nnon-reciprocal when it behaves differently upon the interchange of input and\nresponse. Within the field of metamaterial research on synthetic topological\nmatter, the skin effect describes the conspiracy of non-Hermiticity and\nnon-reciprocity to yield extensive anomalous localization of all eigenmodes in\na (quasi) one-dimensional geometry. Here, we introduce the reciprocal skin\neffect, which occurs in non-Hermitian but reciprocal systems in two or more\ndimensions: Eigenmodes with opposite longitudinal momentum exhibit opposite\ntransverse anomalous localization. We experimentally demonstrate the reciprocal\nskin effect in a passive RLC circuit, suggesting convenient alternative\nimplementations in optical, acoustic, mechanical, and related platforms. Skin\nmode localization brings forth potential applications in directional and\npolarization detectors for electromagnetic waves.",
        "positive": "Unidirectional spin Hall magnetoresistance in topological\n  insulator/ferromagnetic layer heterostructures: The large spin orbit coupling in topological insulators results in helical\nspin-textured Dirac surface states that are attractive for topological\nspintronics. These states generate an efficient spin-orbit torque on proximal\nmagnetic moments at room temperature. However, memory or logic spin devices\nbased upon such switching require a non-optimal three terminal geometry, with\ntwo terminals for the writing current and one for reading the state of the\ndevice. An alternative two terminal device geometry is now possible by\nexploiting the recent discovery of a unidirectional spin Hall magnetoresistance\nin heavy metal/ferromagnet bilayers and (at low temperature) in magnetically\ndoped topological insulator heterostructures. We report the observation of\nunidirectional spin Hall magnetoresistance in a technologically relevant device\ngeometry that combines a topological insulator with a conventional\nferromagnetic metal. Our devices show a figure-of-merit (magnetoresistance per\ncurrent density per total resistance) that is comparable to the highest\nreported values in all-metal Ta/Co bilayers."
    },
    {
        "anchor": "Evolution of excitons via biexcitons to an electron-hole plasma without\n  level crossing between band edge and exciton in a quantum wire: A recent single quantum wire is of sufficient quality to reveal new details\nof the photoluminescence (PL) evolution with increasing electron--hole (e--h)\npair density. At a pair density of 3.6 $\\times$ 10$^{3}$ cm$^{-1}$, the PL is\ncharacteristic of biexcitons shifted below the exciton peak by the 2.8-meV\nbiexciton binding. At the pair density of 1.2 $\\times$ 10$^{5}$ cm$^{-1}$, the\nbiexciton peak broadens without energy shift to an e--h plasma. At all pair\ndensities up to 30 K, neither the exciton peak nor the one-dimensional (1D)\ncontinuum edge shows any shift. In contrast to prevailing theories, the\nlow-energy edge of the plasma PL line never crosses the exciton peak and never\nmakes contact with the 1D e--h continuum.",
        "positive": "A graphene edge-mediated quantum gate: We propose a quantum gate architecture that allows for the systematic control\nof the effective exchange interactions between magnetic impurities embedded in\nnano-scale graphene flakes connected by a gated bridge. The entanglement\nbetween the magnetic moment and the edge states of the fragments is used to\nelectrostatically tune the exchange interaction from ferro to antiferromagnetic\nby merely changing the bridge's carrier density. By characterizing the effects\nof size and coupling parameters, we explore different operation regimes of this\ndevice by means of exact calculations with the density matrix renormalization\ngroup (DMRG). We analyze the results utilizing a simplified model that accounts\nfor the main many-body mechanisms. Finally, we discuss how to use arrays of\nthese devices to build quantum simulators for quantum many-body Hamiltonians."
    },
    {
        "anchor": "Gate-Tunable Tunneling Resistance in Graphene/Topological Insulator\n  Vertical Junctions: Graphene-based vertical heterostructures, particularly stacks incorporated\nwith other layered materials, are promising for nanoelectronics. The stacking\nof two model Dirac materials, graphene and topological insulator, can\nconsiderably enlarge the family of van der Waals heterostructures. Despite well\nunderstanding of the two individual materials, the electron transport\nproperties of a combined vertical heterojunction are still unknown. Here we\nshow the experimental realization of a vertical heterojunction between Bi2Se3\nnanoplate and monolayer graphene. At low temperatures, the electron transport\nthrough the vertical heterojunction is dominated by the tunneling process,\nwhich can be effectively tuned by gate voltage to alter the density of states\nnear the Fermi surface. In the presence of a magnetic field, quantum\noscillations are observed due to the quantized Landau levels in both graphene\nand the two-dimensional surface states of Bi2Se3. Furthermore, we observe an\nexotic gate-tunable tunneling resistance under high magnetic field, which\ndisplays resistance maxima when the underlying graphene becomes a quantum Hall\ninsulator.",
        "positive": "Strong Coupling Between Whispering Gallery Photons and Spin States of\n  Iron Group Impurity Ions: Interaction of Whispering Gallery Modes (WGM) with dilute spin ensembles in\nsolids is an interesting paradigm of Hybrid Quantum Systems potentially\nbeneficial for Quantum Signal Processing applications. In the present work, WGM\nspectroscopy of Rare-Earth doped YSO crystal reveals the existence of Iron\nGroup Ion (IGI) co-dopings with concentration levels of order 100 ppb. The IGI\nspin ensembles demonstrate large Zero Field Splittings at 14.7GHz, 18.4GHz and\n25.4GHz, considerable anisotropy of the \\textrm{g}-tensors, as well as two\ninequivalent lattice sites. Strong coupling regimes between an ensemble of IGI\nspins and WGM photons have been demonstrated at $18.4$ GHz and near zero field.\nThis approach together with useful optical properties of these ions opens a new\navenue for 'spins-in-solids' Quantum Electrodynamics."
    },
    {
        "anchor": "Linear magnetotransport in monolayer MoS$_2$: A momentum balance equation is developed to investigate the magnetotransport\nproperties in monolayer molybdenum disulphide when a strong perpendicular\nmagnetic field and a weak in-plane electric field are applied simultaneously.\nAt low temperature, in the presence of intravalley impurity scattering\nShubnikov de Haas oscillation shows up accompanying by a beating pattern\narising from large spin splitting and its period may halve due to high-order\noscillating term at large magnetic field for samples with ultrahigh mobility.\nIn the case of intervalley disorders, there exists a magnetic-field range where\nthe magnetoresistivity almost vanishes. For low-mobility layer, a\nphase-inversion of oscillating peaks is acquired in accordance with recent\nexperiment. At high temperature when Shubnikov de Haas oscillation is\nsuppressed, the magnetophonon resonances induced by both optical phonons\n(mainly due to homopolar and Fr\\\"ohlich modes) and acoustic phonons (mainly due\nto intravalley transverse and longitudinal acoustic modes) emerge for suspended\nsystem with high mobility. For the single layer on a substrate, another\nresonance due to surface optical phonons may occur, resulting in a complex\nbehavior of the total magnetoresistance. The beating pattern of magnetophonon\nresonance due to optical phonons can also be observed. However, for\nnonsuspended layer with low mobility, the magnetoresistance oscillation almost\ndisappears and the resistivity increases with field monotonously.",
        "positive": "Microwave resonance of the reentrant insulating quantum Hall phases in\n  the 1st excited Landau Level: We present measurements of the real diagonal microwave conductivity of the\nreentrant insulating quantum Hall phases in the first excited Landau level at\ntemperatures below 50 mK. A resonance is detected around filling factor\n$\\nu=2.58$ and weaker frequency dependence is seen at $\\nu=2.42$ and 2.28.\nThese measurements are consistent with the formation of a bubble phase crystal\ncentered around these $\\nu$ at very low temperatures."
    },
    {
        "anchor": "Filling and wetting transitions at grooved substrates: The wetting and filling properties of a fluid adsorbed on a solid grooved\nsubstrate are studied by means of a microscopic density functional theory. The\ngrooved substrates are modelled using a solid slab, interacting with the fluid\nparticles via long-range dispersion forces, to which a one-dimensional array of\ninfinitely long rectangular grooves is sculpted. By investigating the effect of\nthe groove periodicity and the width of the grooves and the ridges, a rich\nvariety of different wetting morphologies is found. In particular, we show that\nfor a saturated ambient gas, the adsorbent can occur in one of four wetting\nstates characterised by i) empty grooves, ii) filled grooves, iii) a formation\nof mesoscopic hemispherical caps iv) a macroscopically wet surface. The\ncharacter of the transition between particular regimes, that also extend\noff-coexistence, sensitively depends on the model geometry. A temperature at\nwhich the system becomes completely wet is considerably higher than that for a\nflat wall.",
        "positive": "Adiabatic pumping and transport in the Sierpinski-Hofstadter model: Topological phases have been reported on self-similar structures in the\npresence of a perpendicular magnetic field. Here, we present an understanding\nof these phases from a perspective of spectral flow and charge pumping. We\nstudy the Harper-Hofstadter model on self-similar structures constructed from\nthe Sierpinski gasket. We numerically investigate the spectral flow and the\nassociated charge pumping when a flux tube is inserted through the structure\nand the flux through the tube is varied adiabatically. We find that the nature\nof the spectral flow is qualitatively different from that of translationally\ninvariant non-interacting systems with a perpendicular magnetic field. We show\nthat the instantaneous eigenspectra can be used to understand the quantization\nof the charge pumped over a cycle, and hence to understand the topological\ncharacter of the system. We show the correspondence between the local\ncontributions to the Hall conductivity and the spectral flow of the edge-like\nstates. We also show that the edge-like states can be approximated by\neigenstates of the discrete angular-momentum operator, their chiral nature\nbeing a consequence of this."
    },
    {
        "anchor": "Hourglass Fermions: Spatial symmetries in crystals are distinguished by whether they preserve the\nspatial origin. We show how this basic geometric property gives rise to a new\ntopology in band insulators. We study spatial symmetries that translate the\norigin by a fraction of the lattice period, and find that these nonsymmorphic\nsymmetries protect a novel surface fermion whose dispersion is shaped like an\nhourglass; surface bands connect one hourglass to the next in an unbreakable\nzigzag pattern. These exotic fermions are materialized in the large-gap\ninsulators: KHgX (X=As,Sb,Bi), which we propose as the first material class\nwhose topology relies on nonsymmorphic symmetries. Beside the hourglass\nfermion, another surface of KHgX manifests a 3D generalization of the quantum\nspin Hall effect, which has only been observed in 2D crystals. To describe the\nbulk topology of nonsymmorphic crystals, we propose a non-Abelian\ngeneralization of the geometric theory of polarization. Our nontrivial topology\noriginates from an inversion of the rotational quantum numbers, which we\npropose as a fruitful criterion in the search for topological materials.",
        "positive": "Fluctuation theorem for counting-statistics in electron transport\n  through quantum junctions: We demonstrate that the probability distribution of the net number of\nelectrons passing through a quantum system in a junction obeys a steady-state\nfluctuation theorem (FT) which can be tested experimentally by the full\ncounting statistics (FCS) of electrons crossing the lead-system interface. The\nFCS is calculated using a many-body quantum master equation (QME) combined with\na Liouville space generating function (GF) formalism. For a model of two\ncoupled quantum dots, we show that the FT becomes valid for long binning times\nand provide an estimate for the finite-time deviations. We also demonstrate\nthat the Mandel (or Fano) parameter associated with the incoming or outgoing\nelectron transfers show subpoissonian (antibunching) statistics."
    },
    {
        "anchor": "Anisotropy of the anomalous Hall effect in the altermagnet candidate\n  Mn$_5$Si$_3$ films: Altermagnets are compensated magnets belonging to spin symmetry groups that\nallow alternating spin polarizations both in the coordinate space of the\ncrystal and in the momentum space of the electronic structure. In these\nmaterials the anisotropic local crystal environment of the different\nsublattices lowers the symmetry of the system so that the opposite-spin\nsublattices are connected only by rotations, which results in an unconventional\nspin-polarized band structure in the momentum space. This low symmetry of the\ncrystal structure is expected to be reflected in the anisotropy of the\nanomalous Hall effect. In this work, we study the anisotropy of the anomalous\nHall effect in epitaxial thin films of Mn$_5$Si$_3$, an altermagnetic candidate\nmaterial. We first demonstrate a change in the relative N\\'eel vector\norientation when rotating the external field orientation through systematic\nchanges in both the anomalous Hall effect and the anisotropic longitudinal\nmagnetoresistance. We then show that the anomalous Hall effect in this material\nis anisotropic with the N\\'eel vector orientation relative to the crystal\nstructure and that this anisotropy requires high crystal quality and unlikely\ncorrelates with the magnetocrystalline anisotropy. Our results provide further\nsystematic support to the case for considering epitaxial thin films of\nMn$_5$Si$_3$ as an altermagnetic candidate material.",
        "positive": "Spin Hall magnetoresistance as a probe for surface magnetization in\n  Pt/CoFe$_2$O$_4$ bilayers: We study the spin Hall magnetoresistance (SMR) in Pt grown $\\textit{in situ}$\non CoFe$_2$O$_4$ (CFO) ferrimagnetic insulating (FMI) films. A careful analysis\nof the angle-dependent and field-dependent longitudinal magnetoresistance\nindicates that the SMR contains a contribution that does not follow the bulk\nmagnetization of CFO but it is a fingerprint of the complex magnetism at the\nsurface of the CFO layer, thus signaling SMR as a tool for mapping surface\nmagnetization. A systematic study of the SMR for different temperatures and CFO\nthicknesses gives us information impossible to obtain with any standard\nmagnetometry technique. On one hand, surface magnetization behaves\nindependently of the CFO thickness and does not saturate up to high fields,\nevidencing that the surface has its own anisotropy. On the other hand,\ncharacteristic zero-field magnetization steps are not present at the surface\nwhile they are relevant in the bulk, strongly suggesting that antiphase\nboundaries are the responsible of such intriguing features. In addition, a\ncontribution from ordinary magnetoresistance of Pt is identified, which is only\ndistinguishable due to the low resistivity of the $\\textit{in-situ}$ grown Pt."
    },
    {
        "anchor": "Ground state topology of a four-terminal superconducting double quantum\n  dot: In recent years, various classes of systems were proposed to realize\ntopological states of matter. One of them are multiterminal Josephson junctions\nwhere topological Andreev bound states are constructed in the synthetic space\nof superconducting phases. Crucially, the topology in these systems results in\na quantized transconductance between two of its terminals comparable to the\nquantum Hall effect. In this work, we study a double quantum dot with four\nsuperconducting terminals and show that it has an experimentally accessible\ntopological regime in which the non-trivial topology can be measured. We also\ninclude Coulomb repulsion between electrons which is usually present in\nexperiments and show how the topological region can be maximized in parameter\nspace.",
        "positive": "Hall detection of time-reversal symmetry breaking under AC electric driv\n  ing: In a four terminal sample microscopic time-reversibility leads to symmetry\nrelations between resistance measurements where the role of current and voltage\nleads are exchanged. These reciprocity relations are a manifestation of general\nOnsager-Casimir symmetries in equilibrium systems. We investigate\nexperimentally the validity of time reversal symmetry in a\n$GaAs/Ga_{1-x}Al_xAs$ Hall bar irradiated by an external AC field, at zero\nmagnetic field. For inhomogeneous AC fields we find strong deviations from\nreciprocity relations and show that their origin can be understood from the the\nbilliard model of a Hall junction. Under homogeneous irradiation the symmetry\nis more robust, indicating that time-reversal symmetry is preserved."
    },
    {
        "anchor": "Acoustic Phonon Spectrum and Thermal Transport in Nanoporous Alumina\n  Arrays: We report results of a combined investigation of thermal conductivity and\nacoustic phonon spectra in nanoporous alumina membranes with the pore diameter\ndecreasing from D=180 nm to 25 nm. The samples with the hexagonally arranged\npores were selected to have the same porosity of ~13%. The Brillouin-Mandelstam\nspectroscopy measurements revealed bulk-like phonon spectrum in the samples\nwith D=180-nm pores and spectral features, which were attributed to spatial\nconfinement, in the samples with 25-nm and 40-nm pores. The velocity of the\nlongitudinal acoustic phonons was reduced in the samples with smaller pores.\nAnalysis of the experimental data and calculated phonon dispersion suggests\nthat both phonon-boundary scattering and phonon spatial confinement affect heat\nconduction in membranes with the feature sizes D<40 nm.",
        "positive": "Disentangling Majorana fermions from conventional zero energy states in\n  semiconductor quantum wires: Majorana fermions (MFs) are predicted to occur as zero-energy bound states in\nsemiconductor nanowire-superconductor structures. However, in the presence of\ndisorder or smooth confining potentials, these structures can also host\nnon-topological nearly-zero energy states. Here, we demonstrate that the MFs\nand the nearly-zero topologically-trivial states have different characteristic\nsignatures in a tunneling conductance measurement, which allows to clearly\ndiscriminate between them. We also show that low-energy non-topological states\ncan strongly hybridize with metallic states from the leads, which generates the\nsmooth background that characterizes the soft superconducting gap measured in\ntunneling experiments and produces an additional decoherence mechanism for the\nMajorana mode. Our results pave the way for the conclusive identification of\nMFs in a solid state system and provide directions for minimizing quantum\ndecoherence in Majorana wires."
    },
    {
        "anchor": "Sweet-spot operation of a germanium hole spin qubit with highly\n  anisotropic noise sensitivity: Spin qubits defined by valence band hole states comprise an attractive\ncandidate for quantum information processing due to their inherent coupling to\nelectric fields enabling fast and scalable qubit control. In particular, heavy\nholes in germanium have shown great promise, with recent demonstrations of fast\nand high-fidelity qubit operations. However, the mechanisms and anisotropies\nthat underlie qubit driving and decoherence are still mostly unclear. Here, we\nreport on the highly anisotropic heavy-hole $g$-tensor and its dependence on\nelectric fields, allowing us to relate both qubit driving and decoherence to an\nelectric modulation of the $g$-tensor. We also confirm the predicted Ising-type\nhyperfine interaction but show that qubit coherence is ultimately limited by\n$1/f$ charge noise. Finally, we operate the qubit at low magnetic field and\nmeasure a dephasing time of $T_2^*=9.2$ ${\\mu}$s, while maintaining a\nsingle-qubit gate fidelity of 99.94 %, that remains well above 99 % at an\noperation temperature T>1 K. This understanding of qubit driving and\ndecoherence mechanisms are key for the design and operation of scalable and\nhighly coherent hole qubit arrays.",
        "positive": "The Effect of Random Surface Inhomogeneities on Microresonator Spectral\n  Properties: Theory and Modeling at Millimeter Wave Range: The influence of random surface inhomogeneities on spectral properties of\nopen microresonators is studied both theoretically and experimentally. To solve\nthe equations governing the dynamics of electromagnetic fields the method of\neigen-mode separation is applied previously developed with reference to\ninhomogeneous systems subject to arbitrary external static potential. We prove\ntheoretically that it is the gradient mechanism of wave-surface scattering\nwhich is the highly responsible for non-dissipative loss in the resonator. The\ninfluence of side-boundary inhomogeneities on the resonator spectrum is shown\nto be described in terms of effective renormalization of mode wave numbers\njointly with azimuth indices in the characteristic equation. To study\nexperimentally the effect of inhomogeneities on the resonator spectrum, the\nmethod of modeling in the millimeter wave range is applied. As a model object\nwe use dielectric disc resonator (DDR) fitted with external inhomogeneities\nrandomly arranged at its side boundary. Experimental results show good\nagreement with theoretical predictions as regards the predominance of the\ngradient scattering mechanism. It is shown theoretically and confirmed in the\nexperiment that TM oscillations in the DDR are less affected by surface\ninhomogeneities than TE oscillations with the same azimuth indices. The DDR\nmodel chosen for our study as well as characteristic equations obtained\nthereupon enable one to calculate both the eigen-frequencies and the Q-factors\nof resonance spectral lines to fairly good accuracy. The results of\ncalculations agree well with obtained experimental data."
    },
    {
        "anchor": "Thermal and electronic transport characteristics of highly stretchable\n  graphene kirigami: For centuries, cutting and folding the papers with special patterns have been\nused to build beautiful, flexible and complex three-dimensional structures.\nInspired by the old idea of kirigami (paper cutting), and the outstanding\nproperties of graphene, recently graphene kirigami structures were fabricated\nto enhance the stretchability of graphene. However, the possibility of further\ntuning the electronic and thermal transport along the 2D kirigami structures\nhave remained original to investigate. We therefore performed extensive\natomistic simulations to explore the electronic, heat and load transfer along\nvarious graphene kirigami structures. The mechanical response and thermal\ntransport were explored using classical molecular dynamics simulations. We then\nused a real-space Kubo-Greenwood formalism to investigate the charge transport\ncharacteristics in graphene kirigami. Our results reveal that graphene kirigami\nstructures present highly anisotropic thermal and electrical transport.\nInterestingly, we show the possibility of tuning the thermal conductivity of\ngraphene by four orders of magnitude. Moreover, we discuss the engineering of\nkirigami patterns to further enhance their stretchability by more than 10 times\nas compared with pristine graphene. Our study not only provides a general\nunderstanding concerning the engineering of electronic, thermal and mechanical\nresponse of graphene but more importantly can be useful to guide future studies\nwith respect to the synthesis of other 2D material kirigami structures, to\nreach highly flexible and stretchable nanostructures with finely tunable\nelectronic and thermal properties.",
        "positive": "Cavity-mediated electron-photon superconductivity: We investigate electron paring in a two-dimensional electron system mediated\nby vacuum fluctuations inside a nanoplasmonic terahertz cavity. We show that\nthe structured cavity vacuum can induce long-range attractive interactions\nbetween current fluctuations which lead to pairing in generic materials with\ncritical temperatures in the low-Kelvin regime for realistic parameters. The\ninduced state is a pair density wave superconductor which can show a transition\nfrom a fully gapped to a partially gapped phase - akin to the pseudogap phase\nin high-$T_c$ superconductors. Our findings provide a promising tool for\nengineering intrinsic electron interactions in two-dimensional materials."
    },
    {
        "anchor": "Scaling laws for weakly disordered 1D flat bands: We investigate Anderson localization on various 1D structures having flat\nbands. The main focus is on the scaling laws obeyed by the localization length\nat weak disorder in the vicinity of flat-band energies. A careful distinction\nis made between situations where the scaling functions are universal (i.e.,\ndepend on the disorder distribution only through its width) and where they keep\ndepending on the full shape of the disorder distribution, even in the\nweak-disorder scaling regime. Three examples are analyzed in detail. On the\nstub chain, one central flat band is isolated from two lateral dispersive ones.\nThe localization length remains microscopic at weak disorder and exhibits\ndisorder-specific features. On the pyrochlore ladder, the two flat bands are\ntangent to a dispersive one. The localization length diverges with exponent 1/2\nand a non-universal scaling law, whose dependence on the disorder distribution\nis predicted analytically. On the diamond chain, a central flat band intersects\ntwo symmetric dispersive ones. The localization length exhibits two successive\nscaling regimes, diverging first with exponent 4/3 and a universal law, and\nthen (i.e., further away from the pristine flat band) with exponent 1 and a\nnon-universal law. Both scaling functions are also derived by analytical means.",
        "positive": "Kondo Quantum Dots and the Novel Kondo-doublet interaction: We analyze the interactions between two Kondo Quantum Dots connected to a\nRashba-active Quantum Wire. We find that the Kondo-doublet interaction, at an\ninter-dot distance of the order of the wire Fermi length, is over an order of\nmagnitude greater than the RKKY interaction. The effects induced on the\nKondo-doublet interaction by the wire spin-orbit coupling can be used to\ncontrol the Quantum Dots spin-spin correlation. These results imply that the\nwidely used assumption that the RKKY is the dominant interaction between\nAnderson impurities must be revised."
    },
    {
        "anchor": "Energy-driven Drag at Charge Neutrality in Graphene: Coulomb coupling between proximal layers in graphene heterostructures results\nin efficient energy transfer between the layers. We predict that, in the\npresence of correlated density inhomogeneities in the layers, vertical energy\ntransfer has a strong impact on lateral charge transport. In particular, for\nCoulomb drag it dominates over the conventional momentum drag near zero doping.\nThe dependence on doping and temperature, which is different for the two drag\nmechanisms, can be used to separate these mechanisms in experiment. We predict\ndistinct features such as a peak at zero doping and a multiple sign reversal,\nwhich provide diagnostics for this new drag mechanism.",
        "positive": "Direction-dependent conductivity in planar Hall set-ups with tilted\n  Weyl/multi-Weyl semimetals: We compute the magnetoelectric conductivity tensors in planar Hall set-ups,\nwhich are built with tilted Weyl semimetals (WSMs) and multi-Weyl semimetals\n(mWSMs), considering distinct relative orientations of the electromagnetic\nfields ($\\mathbf E $ and $\\mathbf B $) and the direction of the tilt. The\nnon-Drude part of the response arises from a nonzero Berry curvature in the\nvicinity of the WSM/mWSM node under consideration. Only in the presence of a\nnonzero tilt do we find linear-in-$ | \\mathbf B| $ terms in set-ups where the\ntilt-axis is not perpendicular to the plane spanned by $\\mathbf E $ and $\n\\mathbf B $. The advantage of the emergence of the linear-in-$ B$ terms is\nthat, unlike the various $| \\mathbf B|^2 $-dependent terms that can contribute\nto experimental observations, they have purely a topological origin and they\ndominate the overall response-characteristics in the realistic parameter\nregimes. The important signatures of these terms are that (1) they change the\nperiodicity of the response from $\\pi $ to $2\\pi$, when we consider their\ndependence on the angle $\\theta $ between $\\mathbf E $ and $\\mathbf B $; and\n(2) lead to an overall change in sign of the conductivity, when measured with\nrespect to the $\\mathbf B =0$ case."
    },
    {
        "anchor": "Theoretical analysis of high-field transport in graphene on a substrate: We investigate transport in graphene supported on various dielectrics (SiO2,\nBN, Al2O3, HfO2) through a hydrodynamic model which includes self-heating and\nthermal coupling to the substrate, scattering with ionized impurities, graphene\nphonons and dynamically screened interfacial plasmon-phonon (IPP) modes. We\nuncover that while low-field transport is largely determined by impurity\nscattering, high-field transport is defined by scattering with\ndielectric-induced IPP modes, and a smaller contribution of graphene intrinsic\nphonons. We also find that lattice heating can lead to negative differential\ndrift velocity (with respect to the electric field), which can be controlled by\nchanging the underlying dielectric thermal properties or thickness. Graphene on\nBN exhibits the largest high-field drift velocity, while graphene on HfO2 has\nthe lowest one due to strong influence of IPP modes.",
        "positive": "Nano-Objects Developing at Graphene/Silicon Carbide Interface: We use scanning tunneling microscopy and spectroscopy to study epitaxial\ngraphene grown on a C-face 4H-SiC(000-1) substrate. The results reveal amazing\nnano-objects at the graphene/SiC interface leading to electronic interface\nstates. Their height profiles suggest that these objects are made of packed\ncarbon nanotubes confined vertically and forming mesas at the SiC surface. We\nalso find nano-cracks covered by the graphene layer that, surprisingly, is not\nbroken, with no electronic interface state. Therefore, unlike the above\nnano-objects, these cracks should not affect the carrier mobility."
    },
    {
        "anchor": "Colossal negative magnetoresistance in dilute fluorinated graphene: Adatoms offer an effective route to modify and engineer the properties of\ngraphene. In this work, we create dilute fluorinated graphene using a clean,\ncontrolled and reversible approach. At low carrier densities, the system is\nstrongly localized and exhibits an unexpected, colossal negative\nmagnetoresistance. The zero-field resistance is reduced by a factor of 40 at\nthe highest field of 9 T and shows no sign of saturation. Unusual \"staircase\"\nfield dependence is observed below 5 K. The magnetoresistance is highly\nanisotropic. We discuss possible origins, considering quantum interference\neffects and adatom-induced magnetism in graphene.",
        "positive": "Rashba-Dirac cones at the tungsten surface: Insights from a\n  tight-binding model and thin film subband structure: A tight-binding model of bcc tungsten that includes spin-orbit coupling is\ndeveloped and applied to the surface states of (110) tungsten thin films. The\nmodel describes accurately the anisotropic Dirac cone-like dispersion and\nRashba-like spin polarization of the surface states, including the crucial\neffect of the relaxation of the surface atomic layer of the tungsten towards\nthe bulk. It is shown that the surface relaxation affects the tungsten surface\nstates because it results in increased overlaps between atomic orbitals of the\nsurface atomic layer and nearby layers whereas electric fields that are due to\ncharge transfer between the tungsten and the vacuum near the surface or between\nthe bulk and surface layers do not significantly affect the Rashba-Dirac\nsurface states. It is found that hybridization with bulk modes has differing\nstrengths for thin film surface states belonging to the upper and lower\nRashba-Dirac cones and results in $reversal$ of the directions of travel of\nspin $\\uparrow$ and $\\downarrow$ electrons in most of the upper Rashba-Dirac\ncone relative to those expected from phenomenology. It is also shown that\nintrasite (not intersite) matrix elements of the spin-orbit Hamiltonian are\nprimarily responsible for the formation of the Rashba-Dirac cones, and their\nspin polarization. This finding should be considered when modeling topological\ninsulators, the spin Hall effect and related phenomena."
    },
    {
        "anchor": "Lumped circuit model for inductive antenna spin-wave transducers: We derive a lumped circuit model for inductive antenna spin-wave transducers\nin the vicinity of a ferromagnetic medium. The model considers the antenna's\nOhmic resistance, its inductance, as well as the additional inductance due to\nthe excitation of ferromagnetic resonance or spin waves in the ferromagnetic\nmedium. As an example, the additional inductance is discussed for a wire\nantenna on top of a ferromagnetic waveguide, a structure that is characteristic\nfor many magnonic devices and experiments. The model is used to assess the\nscaling properties and the energy efficiency of inductive antennas. Issues\nrelated to scaling antenna transducers to the nanoscale and possible solutions\nare also addressed.",
        "positive": "Quantum and classical localisation and the Manhattan lattice: We consider a network model, embedded on the Manhattan lattice, of a quantum\nlocalisation problem belonging to symmetry class C. This arises in the context\nof quasiparticle dynamics in disordered spin-singlet superconductors which are\ninvariant under spin rotations but not under time reversal. A mapping exists\nbetween problems belonging to this symmetry class and certain classical random\nwalks which are self-avoiding and have attractive interactions; we exploit this\nequivalence, using a study of the classical random walks to gain information\nabout the corresponding quantum problem. In a field-theoretic approach, we show\nthat the interactions may flow to one of two possible strong coupling regimes\nseparated by a transition: however, using Monte Carlo simulations we show that\nthe walks are in fact always compact two-dimensional objects with a\nwell-defined one-dimensional surface, indicating that the corresponding quantum\nsystem is localised."
    },
    {
        "anchor": "Projective symmetry determined topology in flux Su-Schrieffer-Heeger\n  model: In the field of symmetry-protected topological phases, a common wisdom is\nthat the symmetries fix the topological classifications, but they alone cannot\ndetermine whether a system is topologically trivial or not. Here, we show that\nthis is no longer true in cases where symmetries are projectively represented.\nParticularly, the Zak phase, a topological invariant of a one-dimensional\nsystem, can be entirely determined by the projective symmetry algebra (PSA). To\ndemonstrate this remarkable effect, we propose a minimal model, termed as flux\nSu-Schrieffer-Heeger (SSH) model, where the bond dimerization in the original\nSSH model is replaced by a flux dimerization. We present experimental\nrealization of our flux SSH model in an electric-circuit array, and our\npredictions are directly confirmed by experimental measurement. Our work\nrefreshes the understanding of the relation between symmetry and topology,\nopens up new avenues for exploring PSA determined topological phases, and\nsuggests flux dimerization as a novel approach for designing topological\ncrystals.",
        "positive": "Cooling mechanisms in molecular conduction junctions: While heating of a current carrying Ohmic conductors is an obvious\nconsequence of the diffusive nature of the conduction in such systems, current\ninduced cooling has been recently reported in some molecular conduction\njunctions. In this paper we demonstrate by simple models the possibility of\ncooling molecular junctions under applied bias, and discuss several mechanisms\nfor such an effect. Our model is characterized by single electron tunneling\nbetween electrodes represented by free electron reservoirs through a system\ncharacterized by it electron levels, nuclear vibrations and their structures.\nWe consider cooling mechasims resulting from (a) cooling of one electrode\nsurface by tunneling induced depletion of high energy electrons; (b) cooling by\ncoherent sub resonance electronic transport analogous to atomic laser nduced\ncooling and (c) the incoherent analog of process (b) - cooling by driven\nactivated transport. The non-equilibrium Green function formulation of junction\ntransport is used in the first two cases, while a master equation approach is\napplied in the analysis of the third."
    },
    {
        "anchor": "Electric charge and potential distribution in twisted multilayer\n  graphene: The specifics of charge screening and electrostatic potential spatial\ndistribution in multilayered graphene films placed in between charged\nsubstrates is theoretically analyzed. It is shown that by varying the areal\ncharge densities on the substrates and/or the thickness of the graphene stack\none may tune the doped carriers distribution over the system. When the charge\ndensities on the substrates are weak, the carriers distribution and\nelectrostatic potential profile agree with semimetallic properties of graphene.\nHowever, when the amount of the donated charge is sufficiently large the\ntransition to a metallic-like behavior of the graphene layers occurs. The\npossibilities for experimental observation of the predicted transition are\ndiscussed.",
        "positive": "An attractive critical point from weak antilocalization on fractals: We report a new attractive critical point occurring in the Anderson\nlocalization scaling flow of symplectic models on fractals. The scaling theory\nof Anderson localization predicts that in disordered symplectic two-dimensional\nsystems weak antilocalization effects lead to a metal-insulator transition.\nThis transition is characterized by a repulsive critical point above which the\nsystem becomes metallic. Fractals possess a non-integer scaling of conductance\nin the classical limit which can be continuously tuned by changing the fractal\nstructure. We demonstrate that in disordered symplectic Hamiltonians defined on\nfractals with classical conductance scaling $g \\sim L^{-\\varepsilon}$, for $0 <\n\\varepsilon < \\beta_\\mathrm{max} \\approx 0.15$, the metallic phase is replaced\nby a critical phase with a scale invariant conductance dependent on the fractal\ndimensionality. Our results show that disordered fractals allow an explicit\nconstruction and verification of the $\\varepsilon$ expansion."
    },
    {
        "anchor": "Topologically localized excitons in single graphene nanoribbons: Excitonic emission from atomically precise graphene nanoribbons (GNRs)\nsynthesised on a metal surface is probed with atomic-scale spatial resolution\nusing a scanning tunneling microscopy (STM) approach. A STM-based strategy to\ntransfer the GNRs to a partially insulating surface is used to prevent light\nemission quenching of the ribbons by the metal substrate. Sub-nanometer\nresolved STM-induced fluorescence spectra reveal emission from localized dark\nexcitons build upon the topological end states of the GNRs. A low frequency\nvibronic emission comb whose characteristics change with the GNR length is\nattributed to longitudinal acoustic modes confined to a finite box. Overall,\nour study provides a novel path to investigate the interplay between excitons,\nvibrons and topology in atomically precise graphene nanostructures.",
        "positive": "Electronic properties of InAs/EuS/Al hybrid nanowires: We study the electronic properties of InAs/EuS/Al heterostructures as\nexplored in a recent experiment [S. Vaitiekenas \\emph{et al.}, Nat. Phys.\n(2020)], combining both spectroscopic results and microscopic device\nsimulations. In particular, we use angle-resolved photoemission spectroscopy to\ninvestigate the band bending at the InAs/EuS interface. The resulting band\noffset value serves as an essential input to subsequent microscopic device\nsimulations, allowing us to map the electronic wave function distribution. We\nconclude that the magnetic proximity effects at the Al/EuS as well as the\nInAs/EuS interfaces are both essential to achieve topological superconductivity\nat zero applied magnetic field. Mapping the topological phase diagram as a\nfunction of gate voltages and proximity-induced exchange couplings, we show\nthat the ferromagnetic hybrid nanowire with overlapping Al and EuS layers can\nbecome a topological superconductor within realistic parameter regimes, and\nthat the topological phase can be optimized by external gating. Our work\nhighlights the need for a combined experimental and theoretical effort for\nfaithful device simulation."
    },
    {
        "anchor": "Spin polarized current in a junction of zigzag carbon nanotube: We investigated spin-resolved electronic transport through a junction\ncomposed of a nonmagnetic metal electrode and a zigzag carbon nanotube by means\nof self-consistent Green's function method in the tight binding approximation\nand the unrestricted Hartree-Fock approximation. Our results show that the\nelectric current can be spin-polarized if the coupling of the junction is weak.\nFurther calculations on spin-spin correlation and local density of states\nreveal the existence of magnetic edge states in zigzag carbon nanotubes, which\nis responsible for the observed spin-polarized current and can be controlled by\napplying a gate voltage. We also studied the influence of the nearest-neighbor\nCoulomb interaction and the junction coupling strength on the spin-polarization\nof the current.",
        "positive": "Catching the zitterbewegung: We demonstrate how the zitterbewegung charge oscillations can be detected\nthrough a charge conductance measurement in a three-terminal junction. By\ntuning the spin-orbit interaction strength or an external magnetic field the\nzitterbewegung period can be modulated, translating into complementary\nconductance oscillations in the two outgoing leads of the junction. The\nproposed experimental setup is within the reach of demonstrated technology and\nmaterial parameters, and enables the observation of the so far elusive\nzitterbewegung phenomenon."
    },
    {
        "anchor": "Magnetization dynamics and spin pumping induced by standing elastic\n  waves: The magnetization dynamics induced by standing elastic waves excited in a\nthin ferromagnetic film is described with the aid of micromagnetic simulations\ntaking into account the magnetoelastic coupling between spins and lattice\nstrains. The simulations have been performed for the 2 nm thick Fe81Ga19 film\ndynamically strained by longitudinal and transverse standing waves with various\nfrequencies, which span a wide range around the resonance frequency nu_res of\ncoherent magnetization precession in unstrained Fe81Ga19 film. It is found that\nstanding elastic waves give rise to complex local magnetization dynamics and\nspatially inhomogeneous dynamic magnetic patterns. The spatio-temporal\ndistributions of the magnetization oscillations in standing elastic waves have\nthe form of standing spin waves with the same wavelength. Remarkably, the\namplitude of magnetization precession does not go to zero at the nodes of these\nspin waves, which cannot be precisely described by simple analytical formulae.\nIn the steady-state regime, the magnetization oscillates with the frequency of\nelastic wave, except for the case of longitudinal waves with frequencies well\nbelow nu_res, where the magnetization precesses with a variable frequency\nstrongly exceeding the wave frequency. The precession amplitude at the\nantinodes of standing spin waves strongly increases when the frequency of\nelastic wave becomes close to nu_res. The results obtained for the\nmagnetization dynamics driven by elastic waves are used to calculate the spin\ncurrent pumped from the dynamically strained ferromagnet into adjacent\nparamagnetic metal. Importantly, the transverse charge current created by the\nspin current via the inverse spin Hall effect is high enough to be measured\nexperimentally.",
        "positive": "Magnetic-optical transitions induced by twisted light in quantum dots: It has been theoretically predicted that light carrying orbital angular\nmomentum, or twisted light, can be tuned to have a strong magnetic-field\ncomponent at optical frequencies. We here consider the interaction of these\npeculiar fields with a semiconductor quantum dot and show that the magnetic\ninteraction results in new types of optical transitions. In particular, a\nsingle pulse of such twisted light can drive light-hole-to-conduction band\ntransitions that are cumbersome to produce using conventional Gaussian beams or\neven twisted light with dominant electric fields."
    },
    {
        "anchor": "A-geometrical approach to Topological Insulators with defects: The study of the propagation of electrons with a varying spinor orientability\nis performed using the coordinate transformation method. Topological Insulators\nare characterized by an odd number of changes of the orientability in the\nBrillouin zone. For defects the change in orientability takes place for closed\norbits in real space. Both cases are characterized by nontrivial spin\nconnections. Using this method , we derive the form of the spin connections for\ntopological defects in three dimensional Topological Insulators. On the surface\nof a Topological Insulator, the presence an edge dislocation gives rise to a\nspin connection controlled by torsion. We find that electrons propagate along\ntwo dimensional regions and confined circular contours. We compute for the edge\ndislocations the tunneling density of states. The edge dislocations violates\nparity symmetry resulting in a current measured by the in-plane component of\nthe spin on the surface.",
        "positive": "Phase-Controllable Nonlocal Spin Polarization in Proximitized Nanowires: We study the magnetic and superconducting proximity effects in a\nsemiconducting nanowire (NW) attached to superconducting leads and a\nferromagnetic insulator (FI). We show that a sizable equilibrium spin\npolarization arises in the NW due to the interplay between the superconducting\ncorrelations and the exchange field in the FI. The resulting magnetization has\na nonlocal contribution that spreads in the NW over the superconducting\ncoherence length and is opposite in sign to the local spin polarization induced\nby the magnetic proximity effect in the normal state. For a Josephson-junction\nsetup, we show that the nonlocal magnetization can be controlled by the\nsuperconducting phase bias across the junction. Our findings are relevant for\nthe implementation of Majorana bound states in state-of-the-art hybrid\nstructures."
    },
    {
        "anchor": "Hyperbolic band topology with non-trivial second Chern numbers: Topological band theory establishes a standardized framework for classifying\ndifferent types of topological matters. Recent investigations have shown that\nhyperbolic lattices in non-Euclidean space can also be characterized by\nhyperbolic Bloch theorem. This theory promotes the investigation of hyperbolic\nband topology, where hyperbolic topological band insulators protected by first\nChern numbers have been proposed. Here, we report a new finding on the\nconstruction of hyperbolic topological band insulators with a vanished first\nChern number but a non-trivial second Chern number. Our model possesses the\nnon-abelian translational symmetry of {8,8} hyperbolic tiling. By engineering\nintercell couplings and onsite potentials of sublattices in each unit cell, the\nnon-trivial bandgaps with quantized second Chern numbers can appear. In\nexperiments, we fabricate two types of finite hyperbolic circuit networks with\nperiodic boundary conditions and partially open boundary conditions to detect\nhyperbolic topological band insulators. Our work suggests a new way to engineer\nhyperbolic topological states with higher-order topological invariants.",
        "positive": "Tunable Majorana corner states in a two-dimensional second-order\n  topological superconductor induced by magnetic fields: A two-dimensional second-order topological superconductor exhibits a finite\ngap in both bulk and edges, with the nontrivial topology manifesting itself\nthrough Majorana zero modes localized at the corners, i.e., Majorana corner\nstates. We investigate a time-reversal-invariant topological superconductor in\ntwo dimension and demonstrate that an in-plane magnetic field could transform\nit into a second-order topological superconductor. A detailed analysis reveals\nthat the magnetic field gives rise to mass terms which take distinct values\namong the edges, and Majorana corner states naturally emerge at the\nintersection of two adjacent edges with opposite masses. With the rotation of\nthe magnetic field, Majorana corner states localized around the boundary may\nhop from one corner to a neighboring one and eventually make a full circle\naround the system when the field rotates by $2\\pi$. In the end we briefly\ndiscuss physical realizations of this system."
    },
    {
        "anchor": "Transport properties of copper phthalocyanine based organic electronic\n  devices: Ambipolar charge carrier transport in Copper phthalocyanine (CuPc) is studied\nexperimentally in field-effect transistors and metal-insulator-semiconductor\ndiodes at various temperatures. The electronic structure and the transport\nproperties of CuPc attached to leads are calculated using density functional\ntheory and scattering theory at the non-equilibrium Green's function level. We\ndiscuss, in particular, the electronic structure of CuPc molecules attached to\ngold chains in different geometries to mimic the different experimental setups.\nThe combined experimental and theoretical analysis explains the dependence of\nthe mobilityand the transmission coefficient on the charge carrier type\n(electrons or holes) and on the contact geometry. We demonstrate the\ncorrespondence between our experimental results on thick films and our\ntheoretical studies of single molecule contacts. Preliminary results for\nfluorinated CuPc are discussed.",
        "positive": "Spin-Orbit Proximity Effect in Bi/Co Multilayer: The Role of Interface\n  Scattering: The Spin-Orbit Proximity Effect is the raise of Spin-Orbit Coupling at a\nlayer near to the interface with a strong spin-orbit material. It has been seen\nin several system such as graphene and ferromagnetic layers. The control of the\nSpin-Orbit Coupling can be a pathway to discover novel and exotic phases in\nsuperconductor and semimetallic systems. Here, we study the magnetoelectrical\ntransport, i.e., magnetoresistance and anomalous Hall effect, in Cobalt/Bismuth\nmultilayers looking for traces of spin-orbit proximity effect and evaluate the\norigin of such effect. Our results point for an increase of Spontaneous\nMagnetic Anisotropy of Resistivity and Anomalous Hall Resistivity at very low\nthicknesses of Cobalt. The analysis of the Anomalous Hall Resisitivity indicate\nthat the Bismuth layers change the scattering mechanism of Hall effect to the\nextrinsic skew-scattering type, indicating that the spin-orbit proximity effect\ncould be related to the elastic scattering of cobalt free carriers by bismuth\nsites at the interface."
    },
    {
        "anchor": "On the Connection of Anisotropic Conductivity to Tip Induced Space\n  Charge Layers in Scanning Tunneling Spectroscopy of p-doped GaAs: The electronic properties of shallow acceptors in p-doped GaAs{110} are\ninvestigated with scanning tunneling microscopy at low temperature. Shallow\nacceptors are known to exhibit distinct triangular contrasts in STM images for\ncertain bias voltages. Spatially resolved I(V)-spectroscopy is performed to\nidentify their energetic origin and behavior. A crucial parameter - the STM\ntip's work function - is determined experimentally. The voltage dependent\npotential configuration and band bending situation is derived. Ways to validate\nthe calculations with the experiment are discussed. Differential conductivity\nmaps reveal that the triangular contrasts are only observed with a depletion\nlayer present under the STM tip. The tunnel process leading to the anisotropic\ncontrasts calls for electrons to tunnel through vacuum gap and a finite region\nin the semiconductor.",
        "positive": "Note on the numerical solution of the scalar Helmholtz equation in a\n  nanotorus with uniform Dirichlet boundary conditions: This note describes the solution of the Helmholtz equation inside a nanotorus\nwith uniform Dirichlet boundary conditions. The eigenfunction symmetry is\ndiscussed and the lower-order eigenvalues and eigenfunctions are shown. The\nsimilarity with the case of a long cylinder and with that of the vibrations of\na circular elastic membrane is discussed. This similarity is used to propose a\nclassification scheme of the eigenfunctions based on three indices."
    },
    {
        "anchor": "Spin-Layer Locking Effects in Optical Orientation of Exciton Spin in\n  Bilayer WSe2: Coupling degrees of freedom of distinct nature plays a critical role in\nnumerous physical phenomena. The recent emergence of layered materials provides\na laboratory for studying the interplay between internal quantum degrees of\nfreedom of electrons. Here, we report experimental signatures of new coupling\nphenomena connecting real spin with layer pseudospins in bilayer WSe2. In\npolarization-resolved photoluminescence measurements, we observe large spin\norientation of neutral and charged excitons generated by both circularly and\nlinearly polarized light, with a splitting of the trion spectrum into a doublet\nat large vertical electrical field. These observations can be explained by\nlocking of spin and layer pseudospin in a given valley. Because up and down\nspin states are localized in opposite layers, spin relaxation is substantially\nsuppressed, while the doublet emerges as a manifestation of electrically\ninduced spin splitting resulting from the interlayer bias. The observed\ndistinctive behavior of the trion doublet under circularly and linearly\npolarized light excitation further provides spectroscopic evidence of\ninterlayer and intralayer trion species, a promising step toward optical\nmanipulation in van der Waals heterostructures through the control of\ninterlayer excitons.",
        "positive": "Co-sputtered PtMnSb thin films and PtMnSb/Pt bilayers for spin-orbit\n  torque investigations: The manipulation of the magnetization by spin-orbit torques (SOTs) has\nrecently been extensively studied due to its potential for efficiently writing\ninformation in magnetic memories. Particular attention is paid to\nnon-centrosymmetric systems with space inversion asymmetry, where SOTs emerge\neven in single-layer materials. The half-metallic half-Heusler PtMnSb is an\ninteresting candidate for studies of this intrinsic SOT. Here, we report on the\ngrowth and epitaxial properties of PtMnSb thin films and PtMnSb/Pt bilayers\ndeposited on MgO(001) substrates by dc magnetron co-sputtering at high\ntemperature in ultra-high vacuum. The film properties were investigated by\nx-ray diffraction, x-ray reflectivity, atomic force microscopy, and electron\nmicroscopy. Thin PtMnSb films present a monocrystalline C1b phase with (001)\norientation, coexisting at increasing thickness with a polycrystalline phase\nwith (111) texture. Films thinner than about 5 nm grow in islands, whereas\nthicker films grow layer-by-layer, forming a perfect MgO/PtMnSb interface. The\nthin PtMnSb/Pt bilayers also show island growth and a defective transition\nzone, while thicker films grow layer-by-layer and Pt grows epitaxially on the\nhalf-Heusler compound without significant interdiffusion."
    },
    {
        "anchor": "2D SnS: a phosphorene analogue with strong in-plane electronic\n  anisotropy: We study the anisotropic electronic properties of 2D SnS, an analogue of\nphosphorene, grown by physical vapor transport. With transmission electron\nmicroscope and polarized Raman spectroscopy, we identify the zigzag and\narmchair directions of the as-grown 2D crystals. 2D SnS field-effect\ntransistors with a cross-Hall-bar structure are fabricated. They show heavily\nhole-doped (~10$^{19}$ cm$^{-3}$) conductivity with strong in-plane anisotropy.\nAt room temperature the mobility along the zigzag direction exceeds 20\ncm$^{2}$V$^{-1}$s$^{-1}$, which can be up to 1.7 times of that in the armchair\ndirection. This strong anisotropy is then explained by the effective-mass ratio\nalong the two directions and agrees well with previous theoretical predictions.\nTemperature-dependent carrier density is used to find out the acceptor energy\nlevel to be ~45 meV above the valence band maximum. This value matches with a\ncalculated defect level of 42 meV for Sn vacancies, indicating that Sn\ndeficiency is the main cause of the p-type conductivity.",
        "positive": "Boron and nitrogen doping in graphene antidot lattices: Bottom-up fabrication of graphene antidot lattices (GALs) has previously\nyielded atomically precise structures with sub-nanometer periodicity. Focusing\non this type of experimentally realized GAL, we perform density functional\ntheory calculations on the pristine structure as well as GALs with edge carbon\natoms substituted with boron or nitrogen. We show that p- and n-type doping\nlevels emerge with activation energies that depend on the level of\nhydrogenation at the impurity. Furthermore, a tight-binding parameterization\ntogether with a Green's function method are used to describe more dilute\ndoping."
    },
    {
        "anchor": "Boundary-obstructed topological phases: Symmetry protected topological (SPT) phases are gapped phases of matter that\ncannot be deformed to a trivial phase without breaking the symmetry or closing\nthe bulk gap. Here, we introduce a new notion of a topological obstruction that\nis not captured by bulk energy gap closings in periodic boundary conditions.\nMore specifically, we say two bulk Hamiltonians belong to distinct boundary\nobstructed topological `phases' (BOTPs) if they can be deformed to each other\non a system with periodic boundaries, but cannot be deformed to each other for\nsymmetric open boundaries without closing the gap at at least one high symmetry\nregion on the surface. BOTPs are not topological phases of matter in the\nstandard sense since they are adiabatically deformable to each other on a torus\nbut, similar to SPTs, they are associated with boundary signatures in open\nsystems such as surface states or fractional corner or hinge charges. We show\nthat the double-mirror quadrupole model of [Science, 357(6346), 2018] is a\nprototypical example of such phases, and present a detailed analysis of several\naspects of boundary obstructions in this model. In addition, we introduce\nseveral three-dimensional models having boundary obstructions, which are\ncharacterized either by surface states or fractional corner or hinge charges.\nWe also provide a general framework to study boundary obstructions in\nfree-fermion systems in terms of Wannier band representations (WBR), an\nextension of the recently-developed band representation formalism to Wannier\nbands. WBRs capture the notion of topological obstructions in the Wannier bands\nwhich can then be used to study topological obstructions in the boundary\nspectrum by means of the correspondence between the Wannier and boundary\nspectra. This establishes a form of bulk-boundary correspondence for BOTPs by\nrelating the bulk band representation to the boundary topology.",
        "positive": "Sign Changes of Intrinsic Spin Hall Effect in Semiconductors and Simple\n  Metals: First-Principles Calculations: First-principles calculations are applied to study spin Hall effect in\nsemiconductors and simple metals. We found that intrinsic spin Hall\nconductivity (ISHC) in realistic materials shows rich sign changes, which may\nbe used to distinguish the effect from the extrinsic one. The calculated ISHC\nin n-doped GaAs can be well compared with experiment, and it differs from the\nsign obtained from the extrinsic effect. On the other hand, the ISHC in W and\nAu, which shows opposite sign respectively, is robust and not sensitive to the\ndisorder."
    },
    {
        "anchor": "Spin-orbit interaction in quantum dots in the presence of exchange\n  correlations: We discuss the problem of spin-orbit interaction in a 2D chaotic or diffusive\nquantum dot in the presence of exchange correlations. Spin-orbit scattering\nbreaks spin rotation invariance, and in the crossover regime between different\nsymmetries of the spin-orbit coupling, the problem has no closed solution. A\nconventional choice of a many-particle basis in a numerical diagonalization is\nthe set of Slater determinants built from the single-particle eigenstates of\nthe one-body Hamiltonian (including the spin-orbit terms). We develop a\ndifferent approach based on the use of a good-spin many-particle basis that is\ncomposed of the eigenstates of the universal Hamiltonian in the absence of\nspin-orbit scattering. We introduce a complete labelling of this good-spin\nbasis and use angular momentum algebra to calculate in closed form the matrix\nelements of the spin-orbit interaction in this basis. Spin properties, such as\nthe ground-state spin distribution and the spin excitation function, are easily\ncalculated in this basis.",
        "positive": "Tunneling transport in devices with semiconducting leads: This paper extends the modern theory of tunneling transport to finite\ntemperatures. The extension enables applications to molecular electronic\ndevices connected to semiconducting leads. The paper presents an application of\nthe theory to molecular devices made of alkyl chains connected to silicon\nnano-wires, mapping their transport characteristics as functions of temperature\nand alkyl chain's length. Based on these calculations and on the analytic\ntheory, it is found that the tunneling decay constant is determined not by the\nFermi level, but by the edge of the valence or conductance band, whichever is\ncloser to the Fermi level. Further insight is provided by mapping the\nevanescent transport channels of the alkyl chains and few other physical\nquantities appearing in the analytic formula for conductance. A good\nqualitative agreement with the experimental data is obtained."
    },
    {
        "anchor": "Cryogenic Magneto-Terahertz Scanning Near-field Optical Microscope\n  (cm-SNOM): We have developed a versatile near-field microscopy platform that can operate\nat high magnetic fields and below liquid-helium temperatures. We use this\nplatform to demonstrate an extreme terahertz (THz) nanoscope operation and to\nobtain the first cryogenic magneto-THz time-domain nano-spectroscopy/imaging at\ntemperatures as low as 1.8 K and magnetic fields of up to 5 T simultaneously.\nOur cryogenic magneto-THz scanning near-field optical microscopy, or cm-SNOM,\ninstrument comprises three main equipment: i) a 5 T split pair magnetic\ncryostat with a custom made insert for mounting SNOM inside; ii) an atomic\nforce microscope (AFM) unit that accepts ultrafast THz excitation and iii) a\nMHz repetition rate, femtosecond laser amplifier for high-field THz pulse\ngeneration and sensitive detection. We apply the cm-SNOM to obtain proof of\nprinciple measurements of superconducting and topological materials. The new\ncapabilities demonstrated break grounds for studying quantum materials that\nrequires extreme environment of cryogenic operation and applied magnetic fields\nsimultaneously in nanometer space, femtosecond time, and terahertz energy\nscales.",
        "positive": "Observation of the intrinsic magnetic susceptibility of highly purified\n  single-wall carbon nanotubes: We report the observation of the intrinsic magnetic susceptibility of highly\npurified SWCNT samples prepared by a combination of acid treatment and density\ngradient ultracentrifugation (DGU). We observed that the diamagnetic\nsusceptibility of SWCNTs increases linearly with increasing nanotube diameter.\nWe found that the magnetic susceptibility divided by the diameter is a\nuniversal function of the scaled temperature. Furthermore, the estimated\nmagnetic susceptibilities of pure semiconducting and pure metallic SWCNT\nsamples suggest that they respond differently to changes in carrier density,\nwhich is consistent with theory. These findings provide experimental\nverification of the theoretically predicted diameter, temperature, and\nmetallicity dependence of the magnetic susceptibility."
    },
    {
        "anchor": "Intersubband electroluminescent devices operating in the strong coupling\n  regime: We present a detailed study of the electroluminescence of intersubband\ndevices operating in the light-matter strong coupling regime. The devices have\nbeen characterized by performing angle resolved spectroscopy that shows two\ndistinct light intensity spots in the momentum-energy phase diagram. These two\nfeatures of the electroluminescence spectra are associated with photons emitted\nfrom the lower polariton branch and from the weak coupling of the intersubband\ntransition with an excited cavity mode. The same electroluminescent active\nregion has been processed into devices with and without the optical microcavity\nto illustrate the difference between a device operating in the strong and weak\ncoupling regime. The spectra are very well simulated as the product of the\npolariton optical density of states, and a function describing the energy\nwindow in which the polariton states are populated. The voltage evolution of\nthe spectra shows that the strong coupling regime allows the observation of the\nelectroluminescence at energies otherwise inaccessible.",
        "positive": "Evidence of a new quantum state of nano-confined water: Deep Inelastic Neutron Scattering provides a means of directly and accurately\nmeasuring the momentum distribution of protons in water, which is determined\nprimarily by the protons ground state wavefunction. We find that in water\nconfined on scales of 20A, this wave function responds to the details of the\nconfinement, corresponds to a strongly anharmonic local potential, shows\nevidence in some cases of coherent delocalization in double wells, and involves\nchanges in zero point kinetic energy of the protons from -40 to +120 meV\ndifference from that of bulk water at room temperature. This behavior appears\nto be a generic feature of nanoscale confinement. It is exhibited here in 16A\ninner diameter carbon nanotubes, two different hydrated proton exchange\nmembranes(PEMs), Nafion 1120 and Dow 858, and has been seen earlier in xerogel\nand 14A diameter carbon nanotubes. The proton conductivity in the PEM samples\ncorrelates with the degree of coherent delocalization of the proton."
    },
    {
        "anchor": "Comment on \"Continuous quantum measurement: inelastic tunneling and lack\n  of current oscillations\": This is a comment on recent paper by T.M. Stace and S.D. Barrett, PRL 92,\n136802 (2004). We show that the main result of the paper, absence of the\nspectral peak for continuous weak measurement of coherent oscillations in a\nqubit, is incorrect.",
        "positive": "Description of electron transport dynamics in molecular devices: A\n  time-dependent density functional theoretical approach in momentum space\n  makes it simple: We propose a first-principles time-dependent density functional theoretical\n(TDDFT) approach in momentum (P) space for quantitative study of electron\ntransport in molecular devices under arbitrary biases. In this approach, the\nbasic equation of motion is a time-dependent integrodifferential equation\nobtained by Fourier transform of the time-dependent Kohn-Sham (TDKS) equation\nin spatial coordinate (R) space. It is formally exact and includes all the\neffects and information of the electron transport in molecular devices. The\nelectron wavefunction is calculated by solving this equation in a closed finite\nP-space volume. This approach is free of self-energy function and memory term\nand beyond the wide-band limit (WBL). The feasibility and power of the approach\nare demonstrated by the calculation of current through one-dimensional (1D)\nsystems."
    },
    {
        "anchor": "Activation of a supercooled liquid confined in a nanopore: It is well stablished that confinement of supercooled liquids in nano-pores\ninduces various effects as a strong modification of the dynamics and a layering\nof the local structure. In this work we raise the issue as how these\nconfinement effects are modified when the liquid is out of equilibrium. To\nanswer that question, we use molecular dynamics simulations to investigate the\neffect of confinement on a supercooled liquid activated by the periodic folding\nof a molecular motor. We find that the motor opening angle controls the\nactivation of the medium and use that result to study the effect of different\nactivations on the confined supercooled liquid. We observe an increase of the\nactivation effect on the dynamics when the medium is confined. We find that the\nconfinement slowing down dependence with the pore radius depends on the\nactivation of the liquid. We argue that these findings result from a\nmodification of dynamic correlation lengths with activation. In this picture\nthe activation permits to control the liquid correlation length and dynamics\ninside the pore. Studying the local structure we observe a modification of the\nlayering organization induced by the activation. We also find that the mobility\ninside the pore depends on the layers, being larger where the local density is\nsmall.",
        "positive": "Evidence for Adsorbate-Enhanced Field Emission from Carbon Nanotube\n  Fibers: We used residual gas analysis (RGA) to identify the species desorbed during\nfield emission (FE) from a carbon nanotube (CNT) fiber. The RGA data show a\nsharp threshold for H2 desorption at an external field strength that coincides\nwith a breakpoint in the FE data. A comprehensive model for the gradual\ntransition of FE from adsorbate-enhanced CNTs at low bias to FE from CNTs with\nreduced H2 adsorbate coverage at high bias is developed which accounts for the\ngradual desorption of the H2 adsorbates, alignment of the CNTs at the fiber\ntip, and importance of self-heating effects with applied bias."
    },
    {
        "anchor": "Anisotropic Etching of Graphite and Graphene in a Remote Hydrogen Plasma: We investigate the etching of a pure hydrogen plasma on graphite samples and\ngraphene flakes on SiO$_2$ and hexagonal Boron-Nitride (hBN) substrates. The\npressure and distance dependence of the graphite exposure experiments reveals\nthe existence of two distinct plasma regimes: the direct and the remote plasma\nregime. Graphite surfaces exposed directly to the hydrogen plasma exhibit\nnumerous etch pits of various size and depth, indicating continuous defect\ncreation throughout the etching process. In contrast, anisotropic etching\nforming regular and symmetric hexagons starting only from preexisting defects\nand edges is seen in the remote plasma regime, where the sample is located\ndownstream, outside of the glowing plasma. This regime is possible in a narrow\nwindow of parameters where essentially all ions have already recombined, yet a\nflux of H-radicals performing anisotropic etching is still present. At the\nrequired process pressures, the radicals can recombine only on surfaces, not in\nthe gas itself. Thus, the tube material needs to exhibit a sufficiently low H\nradical recombination coefficient, such a found for quartz or pyrex. In the\nremote regime, we investigate the etching of single layer and bilayer graphene\non SiO$_2$ and hBN substrates. We find isotropic etching for single layer\ngraphene on SiO$_2$, whereas we observe highly anisotropic etching for graphene\non a hBN substrate. For bilayer graphene, anisotropic etching is observed on\nboth substrates. Finally, we demonstrate the use of artificial defects to\ncreate well defined graphene nanostructures with clean crystallographic edges.",
        "positive": "On resonant scatterers as a factor limiting carrier mobility in graphene: We show that graphene deposited on a substrate has a non-negligible density\nof atomic scale defects. This is evidenced by a previously unnoticed D peak in\nthe Raman spectra with intensity of about 1% with respect to the G peak. We\nevaluated the effect of such impurities on electron transport by mimicking them\nwith hydrogen adsorbates and measuring the induced changes in both mobility and\nRaman intensity. If the intervalley scatterers responsible for the D peak are\nmonovalent, their concentration is sufficient to account for the limited\nmobilities achievable in graphene on a substrate."
    },
    {
        "anchor": "Skyrmion ratchet propagation: Utilizing the skyrmion Hall effect in AC\n  racetrack storage devices: Magnetic skyrmions are whirl-like nano-objects with topological protection.\nWhen driven by direct currents (DC), skyrmions move but experience a transverse\ndeflection. This so-called skyrmion Hall effect is often regarded a drawback\nfor memory applications. Herein, we show that this unique effect can also be\nfavorable for spintronic applications: We show that in a racetrack with a\nbroken inversion symmetry, the skyrmion Hall effect allows to translate an\nalternating current (AC) into a directed motion along the track, like in a\nratchet. We analyze several modes of the ratchet mechanism and show that it is\nunique for topological magnetic whirls. We elaborate on the fundamental\ndifferences compared to the motion of topologically trivial magnetic objects,\nas well as classical particles driven by periodic forces. Depending on the\nexact racetrack geometry, the ratchet mechanism can be soft or strict. In the\nlatter case, the skyrmion propagates close to the efficiency maximum.",
        "positive": "Local Symmetries and Order-Disorder Transitions in Small Macroscopic\n  Wigner Islands: The influence of local order on the disordering scenario of small Wigner\nislands is discussed. A first disordering step is put in evidence by the time\ncorrelation functions and is linked to individual excitations resulting in\nconfiguration transitions, which are very sensitive to the local symmetries.\nThis is followed by two other transitions, corresponding to orthoradial and\nradial diffusion, for which both individual and collective excitations play a\nsignificant role. Finally, we show that, contrary to large systems, the focus\nthat is commonly made on collective excitations for such small systems through\nthe Lindemann criterion has to be made carefully in order to clearly identify\nthe relative contributions in the whole disordering process."
    },
    {
        "anchor": "Imaging electrons in a magnetic field: We present simulations of an imaging mechanism that reveals the trajectories\nof electrons in a two-dimensional electron gas (2DEG), as well as simulations\nof the electron flow in zero and small magnetic fields. The end goal of this\nwork is to implement the proposed mechanism to image the flow of electrons\ninside a ballistic electron device from one specific point (A) to another (B)\nin a 2DEG, using a low temperature scanning probe microscope with a charged\ntip. The tip changes the electron density in the 2DEG beneath it and deflects\nthe electrons traveling nearby, thereby changing the conductance from point A\nto point B. The simulations presented here show that by measuring the\ntransmission of electrons from A to B versus tip position, one can image the\nelectron flow. This forward scattering mechanism is well suited for imaging in\na magnetic field, in contrast to previous probes that depended on\nbackscattering. One could use this technique to image cyclotron orbits in an\nelectron focusing geometry, in which electrons travel from point A to point B\nin semi-circular paths bouncing along a wall. Imaging the motion of electrons\nin magnetic fields is useful for the development of devices for spintronics and\nquantum information processing.",
        "positive": "Dependence of the 0.5(2e2/h) conductance plateau on the aspect ratio of\n  InAs quantum point contacts with in-plane side gates: The observation of a 0.5 conductance plateau in asymmetrically biased quantum\npoint contacts with in-plane side gates has been attributed to the onset of\nspin-polarized current through these structures. For InAs quantum point\ncontacts with the same width but longer channel length, there is roughly a\nfourfold increase in the range of common sweep voltage applied to the side\ngates over which the 0.5 conductance plateau is observed when the QPC aspect\nratio (ratio of length over width of the narrow portion of the structure) is\nincreased by a factor 3. Non-equilibrium Green s function simulations indicate\nthat the increase in the size of the 0.5 conductance plateau is due to an\nincreased importance, over a larger range of common sweep voltage, of the\neffects of electron-electron interactions in QPC devices with larger aspect\nratio. The use of asymmetrically biased QPCs with in-plane side gates and large\naspect ratio could therefore pave the way to build robust spin injectors and\ndetectors for the successful implementation of spin field effect transistors"
    },
    {
        "anchor": "Interaction effects in multi-subband quantum wires: We investigate the effect of electron-electron interactions on the transport\nproperties of disordered quasi one-dimensional quantum wires with two or more\nsubbands occupied. We apply two alternative methods to solve the logarithmic\ndivergent problem, namely the parquet graph theory and a renormalization group\ncalculation. We solve the group equations analytically in the weak coupling\nlimit and find a power-law for the temperature dependent conductivity of a\nmulti-channel system. The exponent is roughly equal to the inverse of the\nnumber of the occupied subbands.",
        "positive": "Performance limits of graphene-ribbon-based field effect transistors: The performance of field effect transistors based on an single graphene\nribbon with a constriction and a single back gate are studied with the help of\natomistic models. It is shown how this scheme, unlike that of traditional\ncarbon-nanotube-based transistors, reduces the importance of the specifics of\nthe chemical bonding to the metallic electrodes in favor of the carbon-based\npart of device. The ultimate performance limits are here studied for various\nconstriction and metal-ribbon contact models. In particular we show that, even\nfor poorly contacting metals, properly taylored constrictions can give\npromising values for both the on-conductance and the subthreshold swing."
    },
    {
        "anchor": "Effect of inelastic scattering on spin entanglement detection through\n  current noise: We study the effect of inelastic scattering on the spin entanglement\ndetection and discrimination scheme proposed by Egues, Burkard, and Loss [Phys.\nRev. Lett. \\textbf{89}, 176401 (2002)]. The finite-backscattering beam splitter\ngeometry is supplemented by a phenomenological model for inelastic scattering,\nthe charge-conserving voltage probe model, conveniently generalized to deal\nwith entangled states. We find that the behavior of shot-noise measurements in\none of the outgoing leads remains an efficient way to characterize the nature\nof the non-local spin correlations in the incoming currents for an inelastic\nscattering probability up to 50%. Higher order cumulants are analyzed, and are\nfound to contain no additional useful information on the spin correlations. The\ntechnique we have developed is applicable to a wide range of systems with\nvoltage probes and spin correlations.",
        "positive": "A simple approach to characterizing band topology in bosonic pairing\n  Hamiltonians: We revisit the problem of characterizing band topology in dynamically-stable\nquadratic bosonic Hamiltonians that do not conserve particle number. We show\nthis problem can be rigorously addressed by a smooth and local adiabatic\nmapping procedure to a particle number conserving Hamiltonian. In contrast to a\ngeneric fermionic pairing Hamiltonian, such a mapping can always be constructed\nfor bosons. Our approach shows that particle non-conserving bosonic\nHamiltonians can be classified using known approaches for fermionic models. It\nalso provides a simple means for identifying and calculating appropriate\ntopological invariants. We also explicitly study dynamically stable but\nnon-positive definite Hamiltonians (as arise frequently in driven photonic\nsystems). We show that in this case, each band gap is characterized by two\ndistinct invariants."
    },
    {
        "anchor": "Radiation-free and non-Hermitian topology inertial defect states of\n  on-chip magnons: Radiative damping is a strong dissipation source for the quantum emitters\nhybridized with propagating photons, electrons, or phonons, which is not easily\navoidable for on-chip magnonic emitters as well that can radiate via the\nsurface acoustic waves of the substrate. Here we demonstrate in an array of\non-chip nano-magnets coupled in a long range via exchanging the surface\nacoustic waves that a point defect in the array, which can be introduced by the\nlocal magnon frequency shift by a local biased magnetic field or the absence of\na magnetic wire, strongly localizes the magnons, in contrast to the well\nspreading Bloch-like collective magnon modes in such an array setting. The\nradiation of the magnon defect states is exponentially suppressed by the\ndistance of the defect to the array edges. Moreover, this defect state is\nstrikingly inertial to the non-Hermitian topology that localizes all the\nextended states at one boundary. Such configuration robust magnon defect states\ntowards radiation-free limit may be suitable for high-fidelity magnon quantum\ninformation storage in the future on-chip magnonic devices.",
        "positive": "Emerging exceptional point with breakdown of skin effect in\n  non-Hermitian systems: We study the interplay of two distinct non-Hermitian parameters: directional\ncoupling and onsite gain-loss, together with topology, in coupled\none-dimensional (1D) non-Hermitian Su-Schrieffer-Heeger (SSH) chains. The SSH\nmodel represents one of the simplest two-band models that features boundary\nlocalized topological modes. Our study shows how the merging of two topological\nmodes can lead to a striking spectral feature of non-Hermitian systems, namely\nexceptional point (EP). We reveal the existence EP as a singularity in the\nparameter space of non-Hermitian couplings carrying a half-integer topological\ncharge. We also demonstrate two different localization behaviors observed in\nthe bulk and hybridized topological modes. While the bulk states and individual\ntopological modes remain localized at the boundaries due to skin effect, the\ncompetition between the constituent non-Hermitian parameters can overcome the\nstrength of skin effect and lead to the complete \\textit{delocalization} of\nthese hybridized modes. We obtain explicit analytic solutions for the\neigenfunction and the eigenenergy of the hybridized modes, which exactly match\nthe numerical results and successfully reveal the underlying cause of\ndelocalization and the emergence of EP."
    },
    {
        "anchor": "Fermi liquid theory for nonlinear transport through a multilevel\n  Anderson impurity: We present a microscopic Fermi-liquid view on the low-energy transport\nthrough an Anderson impurity with $N$ discrete levels, at arbitrary electron\nfilling $N_d$. It is applied to nonequilibrium current fluctuations, for which\nthe two-quasiparticle collision integral and the three-body correlations that\ndetermine the quasiparticle energy shift play important roles. Using the\nnumerical renormalization group up to $N=6$, we find that for strong\ninteractions the three-body fluctuations are determined by a single parameter\nother than the Kondo energy scale in a wide filling range $1 \\lesssim N_d\n\\lesssim N-1$. It significantly affects the current noise for $N>2$ and the\nbehavior of noise in magnetic fields.",
        "positive": "Multilayer Graphene Nanoribbon and Carbon Nanotube based Floating Gate\n  Transistor for Nonvolatile Flash Memory: Floating gate transistor is the basic building block of non-volatile flash\nmemory, which is one of the most widely used memory gadgets in modern micro and\nnano electronic applications. Recently there has been a surge of interest to\nintroduce a new generation of memory devices using graphene nanotechnology. In\nthis paper we present a new floating gate transistor (FGT) design based on\nmultilayer graphene nanoribbon (MLGNR) and carbon nanotube (CNT). In the\nproposed FGT a multilayer structure of graphene nanoribbon (GNR) would be used\nas the channel of the field effect transistor (FET) and a layer of CNTs would\nbe used as the floating gate. We have performed an analysis of the charge\naccumulation mechanism in the floating gate and its dependence on the applied\nterminal voltages. Based on our analysis we have observed that proposed\ngraphene based floating gate transistor could be operated at a reduced voltage\ncompared to conventional silicon based floating gate devices. We have presented\ndetail analysis of the operation and the programming and erasing processes of\nthe proposed FGT, dependency of the programming and erasing current density on\ndifferent parameters, impact of scaling the thicknesses of the control and\ntunneling oxides. These analysis are done based on the capacitance model of the\ndevice."
    },
    {
        "anchor": "Probing spin and orbital Kondo effects with a mesoscopic interferometer: We investigate theoretically the transport properties of a closed\nAharonov-Bohm interferometer containing two quantum dots in the strong coupling\nregime. We find two distinct physical scenarios depending on the strength of\nthe interdot Coulomb interaction. When the interdot Coulomb interaction is\nnegligible only spin fluctuations are important and each dot develops a Kondo\nresonance at the Fermi level independently of the applied magnetic flux. The\ntransport is characterized by the interference of these two independent Kondo\nresonances. On the contrary, for large interdot interaction, only one electron\ncan be accommodated onto the double dot system. In this situation, not only the\nspin can fluctuate but also the orbital degree of freedom (the pseudo-spin). As\na result, we find different ground states depending on the value of the applied\nflux. When $\\phi=\\pi$ (mod $2\\pi$) ($\\phi=2\\pi\\Phi/\\Phi_0$, where $\\Phi$ is\napplied flux, and $\\Phi_0=h/e$ the flux quantum) the electronic transport can\ntake place via simultaneous correlations in the spin and pseudo-spin sectors,\nleading to the highly symmetric SU(4) Kondo state. Nevertheless, we find\nsituations with $\\phi>0$ (mod $2\\pi$) where the pseudo-spin quantum number is\nnot conserved during tunneling events, giving rise to the common SU(2) Kondo\nstate with an enhanced Kondo temperature. We investigate the crossover between\nboth ground states and discuss possible experimental signatures of this physics\nas a function of the applied magnetic flux.",
        "positive": "Proximity-induced ferromagnetism and chemical reactivity in few layers\n  VSe2 heterostructures: Among Transition-Metal Dichalcogenides, mono and few-layers thick VSe2 has\ngained much recent attention following claims of intrinsic room-temperature\nferromagnetism in this system, which have nonetheless proved controversial.\nHere, we address the magnetic and chemical properties of Fe/VSe2\nheterostructure by combining element sensitive absorption spectroscopy and\nphotoemission spectroscopy. Our x-ray magnetic circular dichroism results\nconfirm recent findings that both native mono/few-layer and bulk VSe2 do not\nshow any signature of an intrinsic ferromagnetic ordering. Nonetheless, we find\nthat ferromagnetism can be induced, even at room temperature, after coupling\nwith a Fe thin film layer, with antiparallel alignment of the moment on the V\nwith respect to Fe. We further consider the chemical reactivity at the Fe/VSe2\ninterface and its relation with interfacial magnetic coupling."
    },
    {
        "anchor": "Anomalous Hooke's law in disordered graphene: The discovery of graphene, a single monolayer of graphite, has closed the\ndiscussion on stability of 2D crystals. Although thermal fluctuations of such\ncrystals tend to destroy the long-range order in the system, the crystal can be\nstabilized by strong anharmonicity effects. This competition is the central\nissue of the crumpling transition, i.e., a transition between flat and crumpled\nphases. We show that anharmonicity-controlled fluctuations of a graphene\nmembrane around equilibrium flat phase lead to unusual elastic properties. In\nparticular, we demonstrate that stretching $\\xi$ of a flake of graphene is a\nnonlinear function of the applied tension at small tension:\n${\\xi\\propto\\sigma^{\\eta/(2-\\eta)}}$ and ${\\xi\\propto\\sigma^{\\eta/(8-\\eta)}}$\nfor clean and strongly disordered graphene, respectively. Conventional linear\nHooke's law, ${\\xi\\propto\\sigma}$ is realized at sufficiently large tensions:\n${\\sigma\\gg\\sigma_*},$ where $\\sigma_*$ depends both on temperature and on the\ndisorder strength.",
        "positive": "Electrical resistance: an atomistic view: This tutorial article presents a \"bottom-up\" view of electrical resistance\nstarting from something really small, like a molecule, and then discussing the\nissues that arises as we move to bigger conductors. Remarkably, no serious\nquantum mechanics is needed to understand electrical conduction through\nsomething really small, except for unusual things like the Kondo effect that\nare seen only for a special range of parameters. This article starts with\nenergy level diagrams (section 2), shows that the broadening that accompanies\ncoupling limits the conductance to a maximum of q^2/h per level (sections 3,\n4), describes how a change in the shape of the self-consistent potential\nprofile can turn a symmetric current-voltage characteristic into a rectifying\none (sections 5, 6), shows that many interesting effects in molecular\nelectronics can be understood in terms of a simple model (section 7),\nintroduces the non-equilibrium Green function (NEGF) formalism as a\nsophisticated version of this simple model with ordinary numbers replaced by\nappropriate matrices (section 8) and ends with a personal view of unsolved\nproblems in the field of nanoscale electron transport (section 9). Appendix A\ndiscusses the Coulomb blockade regime of transport, while appendix B presents a\nformal derivation of the NEGF equations. MATLAB codes for numerical examples\nare listed in the appendix C."
    },
    {
        "anchor": "Transport in superconductor--normal metal--superconductor tunneling\n  structures: Spinful p-wave and spin-orbit-coupled topological wires: We theoretically study transport properties of voltage-biased one-dimensional\nsuperconductor--normal metal--superconductor tunnel junctions with arbitrary\njunction transparency where the superconductors can have trivial or nontrivial\ntopology. Motivated by recent experimental efforts on Majorana properties of\nsuperconductor-semiconductor hybrid systems, we consider two explicit models\nfor topological superconductors: (i) spinful p-wave, and (ii) spin-split\nspin-orbit-coupled s-wave. We provide a comprehensive analysis of the\nzero-temperature dc current $I$ and differential conductance $dI/dV$ of\nvoltage-biased junctions with or without Majorana zero modes (MZMs). The\npresence of an MZM necessarily gives rise to two tunneling conductance peaks at\nvoltages $eV = \\pm \\Delta_{\\mathrm{lead}}$, i.e., the voltage at which the\nsuperconducting gap edge of the lead aligns with the MZM. We find that the MZM\nconductance peak probed by a superconducting lead $without$ a BCS singularity\nhas a non-universal value which decreases with decreasing junction\ntransparency. This is in contrast to the MZM tunneling conductance measured by\na superconducting lead $with$ a BCS singularity, where the conductance peak in\nthe tunneling limit takes the quantized value $G_M = (4-\\pi)2e^2/h$ independent\nof the junction transparency. We also discuss the \"subharmonic gap structure\",\na consequence of multiple Andreev reflections, in the presence and absence of\nMZMs. Finally, we show that for finite-energy Andreev bound states (ABSs), the\nconductance peaks shift away from the gap bias voltage $eV = \\pm\n\\Delta_{\\mathrm{lead}}$ to a larger value set by the ABSs energy. Our work\nshould have important implications for the extensive current experimental\nefforts toward creating topological superconductivity and MZMs in semiconductor\nnanowires proximity coupled to ordinary s-wave superconductors.",
        "positive": "Current Correlations in a Majorana Beam Splitter: We study current correlations in a $T$-junction composed of a grounded\ntopological superconductor and of two normal-metal leads which are biased at a\nvoltage $V$. We show that the existence of an isolated Majorana zero mode in\nthe junction dictates a universal behavior for the cross correlation of the\ncurrents through the two normal-metal leads of the junction. The cross\ncorrelation is negative and approaches zero at high bias voltages as -1/$V$.\nThis behavior is robust in the presence of disorder and multiple transverse\nchannels, and persists at finite temperatures. In contrast, an accidental\nlow-energy Andreev bound state gives rise to nonuniversal behavior of the cross\ncorrelation. We employ numerical transport simulations to corroborate our\nconclusions."
    },
    {
        "anchor": "Coulomb blockade peak spacing fluctuations in deformable quantum dots: a\n  further test to Random Matrix Theory: We propose a mechanism to explain the fluctuations of the ground state energy\nin quantum dots in the Coulomb blockade regime. Employing the random matrix\ntheory we show that shape deformations may change the adjacent peak spacing\ndistribution from Wigner-Dyson to nearly Gaussian even in the absence of strong\ncharging energy fluctuations. We find that this distribution is solely\ndetermined by the average number of anti-crossings between consecutive\nconductance peaks and the presence or absence of a magnetic field. Our\nmechanism is tested in a dynamical model whose underlying classical dynamics is\nchaotic. Our results are in good agreement with recent experiments and apply to\nquantum dots with spin resolved or spin degenerate states.",
        "positive": "Topological Light Nodal Lines in FCC Lattice: Light cone with the speed of light independent of its wavelength in vacuum\nhas been known for long time. In the present work, we unveil that in a\nface-centered-cubic (fcc) lattice of dielectric spheres novel light cones can\nbe created over closed loops in momentum space, dubbed as nodal lines (NL), and\nthat as a consequence of the nontrivial topology of NL interface states with a\ndrumhead-shaped band structure appear where light can be slowed down\nsignificantly. We discuss that photonic pseudogaps found in previous\nexperimental and theoretical studies for fcc photonic crystals are consistent\nwith the present finding of NL. This offers a unique chance to confirm the\nexistence of NL as a novel topological state."
    },
    {
        "anchor": "Control of topography, stress and diffusion at molecule-metal interface: Transport properties of metal-molecule-metal junctions containing monolayer\nof conjugated and saturated molecules with characteristic dimensions in the\nrange of 30-300 nm are correlated with microscopic topography, stress and\nchemical bonding at metal-molecule interfaces. Our statistically significant\ndataset allows us to conclude that the conductivity of organic molecules ~1.5\nnm long is at least 4 orders of magnitude lower than is commonly believed.",
        "positive": "Optically induced spin-dependent diffusive transport in the presence of\n  spin-orbit interaction for all-optical magnetization reversal: We have considered the effect of different spin-orbit interaction mechanisms\non the process of demagnetization under the influence of short-pulse lasers.\nAll-optical magnetization reversal of perpendicularly magnetized thin films can\noccur if there are sufficient strong spin-Hall, skew scattering, and Rashba\ninteractions. In the presence of spin-orbit interactions, the transient charge\ncurrents provide the generation of transverse-spin currents and accumulations,\nwhich eventually exert spin-transfer torque on the magnetization. By combining\nthe optically excited spin-dependent diffusive transport with the spin and\ncharge currents due to skew scattering, spin-Hall, inverse spin-Hall and Rashba\ninteractions, into a numerical model, we demonstrate a possibility of\nultra-fast all-optical magnetization reversal. This understanding provokes\nintriguing, more in-depth experimental studies on the role of spin-orbit\ninteraction mechanisms in optimizing structures for all-optical magnetization\nreversal."
    },
    {
        "anchor": "Influence of low-frequency noise on macroscopic quantum tunneling in\n  superconducting circuits: The influence of low to moderate frequency environments on Macroscopic\nQuantum Tunneling (MQT) in superconducting circuits is studied within the Im-F\napproach to evaluate tunneling rates. Particular attention is paid to two model\nenvironments, namely, a pure sluggish bath and a sluggish bath with additional\n1/f-noise. General findings are applied to Zener flip tunneling, a MQT\nphenomenon recently predicted and observed in a superconducting circuit\nimplementing a quantum bit.",
        "positive": "Theory of interlayer exchange coupling: This paper contains the notes of lectures on the theory of interlayer\nexchange coupling presented at the 30-th Ferienschule of the Institut fuer\nFestkoerperforschung, Forschungszentrum Juelich, March 1999."
    },
    {
        "anchor": "Electron-hole correlations govern Auger recombination in nanostructures: The fast nonradiative decay of multiexcitonic states via Auger recombination\nis a fundamental process affecting a variety of applications based on\nsemiconductor nanostructures. From a theoretical perspective, the description\nof Auger recombination in confined semiconductor nanostructures is a\nchallenging task due to the large number of valance electrons and exponentially\ngrowing number of excited excitonic and biexcitonic states that are coupled by\nthe Coulomb interaction. These challenges have restricted the treatment of\nAuger recombination to simple, noninteracting electron-hole models. Herein we\npresent a novel approach for calculating Auger recombination lifetimes in\nconfined nanostructures having thousands to tens of thousands of electrons,\nexplicitly including electron-hole interactions. We demonstrate that the\ninclusion of electron-hole correlations are imperative to capture the correct\nscaling of the Auger recombination lifetime with the size and shape of the\nnanostructure. In addition, correlation effects are required to obtain\nquantitatively accurate lifetimes even for systems smaller than the exciton\nBohr radius. Neglecting such correlations can result in lifetimes that are 2\norders of magnitude too long. We establish the utility of the new approach for\nCdSe quantum dots of varying sizes and for CdSe nanorods of varying diameters\nand lengths. Our new approach is the first theoretical method to postdict the\nexperimentally known universal volume scaling law for quantum dots and makes\nnovel predictions for the scaling of the Auger recombination lifetimes in\nnanorods.",
        "positive": "Decoherence and dynamical decoupling control of nitrogen-vacancy center\n  electron spins in nuclear spin baths: We theoretically study the decoherence and the dynamical decoupling control\nof nitrogen-vacancy center electron spins in high-purity diamond, where the\nhyperfine interaction with $^{13}$C nuclear spins is the dominating decoherence\nmechanism. The decoherence is formulated as the entanglement between the\nelectron spin and the nuclear spins, which is induced by nuclear spin bath\nevolution conditioned on the electron spin state. The nuclear spin bath\nevolution is driven by elementary processes such as single spin precession and\npairwise flip-flops. The importance of different elementary processes in the\ndecoherence depends on the strength of the external magnetic field."
    },
    {
        "anchor": "Single-atom dopants in plasmonic nanocatalysts: Bimetallic nanostructures combining plasmonic and catalytic metals are\npromising for tailoring and enhancing plasmonic hot-carrier generation utilized\nin plasmonic catalysis. In this work, we study the plasmonic hot-carrier\ngeneration in noble metal nanoparticles (Ag, Au, Cu) with single-atom dopants\n(Ag, Au, Cu, Pd, Pt) with first-principles time-dependent density-functional\ntheory calculations. Our results show that the local hot-carrier generation at\nthe dopant atom is significantly altered by the dopant element while the\nplasmonic response of the nanoparticle as a whole is not significantly\naffected. In particular, hot holes at the dopant atom originate from the\ndiscrete d-electron states of the dopant. The energies of these d-electron\nstates, and hence those of the hot holes, depend on the dopant element, which\nopens up the possibility to tune hot-carrier generation with suitable dopants.",
        "positive": "Dipolar spin waves in uniaxial easy-axis antiferromagnets: A natural\n  topological nodal-line semimetal: The existence of the magnetostatic surface spin waves in ferromagnets, known\nas Damon-Eshbach mode, was recently demonstrated to originate from the topology\nof the dipole-dipole interaction. In this work, we study the topological\ncharacteristics of magnons in easy-axis antiferromagnets with uniaxial\nanisotropy. The dipolar spin waves are found to be, driven by the dipole-dipole\ninteraction, in a topological nodal-line semimetal phase, which hosts\nDamon-Eshbach-type surface modes due to the bulk-edge correspondence. The long\nwavelength character of dipolar spin waves makes our proposal valid for any\nnatural uniaxial easy-axis antiferromagnet, and thus enriches the candidates of\ntopological magnonic materials. In contrast to the nonreciprocal property in\nferromagnetic case, the surface modes with opposite momentum coexist at each\nsurface, but with different chiralities. Such a chirality-momentum or\nspin-momentum locking, similar to that of electronic surface states in\ntopological insulators, offers the opportunity to design novel chirality-based\nmagnonic devices in antiferromagnets."
    },
    {
        "anchor": "A super-Ohmic energy absorption in driven quantum chaotic systems: We consider energy absorption by driven chaotic systems of the symplectic\nsymmetry class. According to our analytical perturbative calculation, at the\ninitial stage of evolution the energy growth with time can be faster than\nlinear. This appears to be an analog of weak anti-localization in disordered\nsystems with spin-orbit interaction. Our analytical result is also confirmed by\nnumerical calculations for the symplectic quantum kicked rotor.",
        "positive": "Branch-entangled polariton pairs in planar microcavities and photonic\n  wires: A scheme is proposed for the generation of branch-entangled pairs of\nmicrocavity polaritons through spontaneous inter-branch parametric scattering.\nBranch-entanglement is achievable when there are two twin processes, where the\nrole of signal and idler can be exchanged between two different polariton\nbranches. Branch-entanglement of polariton pairs can lead to the emission of\nfrequency-entangled photon pairs out of the microcavity. In planar\nmicrocavities, the necessary phase-matching conditions are fulfilled for\npumping of the upper polariton branch at an arbitrary in-plane wave-vector. The\nimportant role of nonlinear losses due to pair scattering into high-momentum\nexciton states is evaluated. The results show that the lack of protection of\nthe pump polaritons in the upper branch is critical. In photonic wires,\nbranch-entanglement of one-dimensional polaritons is achievable when the pump\nexcites a lower polariton sub-branch at normal incidence, providing protection\nfrom the exciton reservoir."
    },
    {
        "anchor": "Solutions of the Bogoliubov-de Gennes equation with position dependent\n  Fermi--velocity and gap profiles: It is shown that bound state solutions of the one dimensional Bogoliubov-de\nGennes (BdG) equation may exist when the Fermi velocity becomes dependent on\nthe space coordinate. The existence of bound states in continuum (BIC) like\nsolutions has also been confirmed both in the normal phase as well as in the\nsuper-conducting phase. We also show that a combination of Fermi velocity and\ngap parameter step-like profiles provides scattering solutions with normal\nreflection and transmission.",
        "positive": "Electron-Spin-Resonance in a proximity-coupled MoS2/Graphene\n  van-der-Waals heterostructure: Coupling graphene's excellent electron and spin transport properties with\nhigher spin-orbit coupling material allows tackling the hurdle of spin\nmanipulation in graphene, due to the proximity to van-der-Waals layers. Here we\nuse magneto transport measurements to study the electron spin resonance on a\ncombined system of graphene and MoS2 at 1.5K. The electron spin resonance\nmeasurements are performed in the frequency range of 18-33GHz, which allows us\nto determine the g-factor in the system. We measure average g-factor of 1.91\nfor our hybrid system which is a considerable shift compared to what is\nobserved in graphene on SiO2. This is a clear indication of proximity induced\nSOC in graphene in accordance with theoretical predictions."
    },
    {
        "anchor": "Competing zero-field Chern insulators in Superconducting Twisted Bilayer\n  Graphene: The discovery of magic angle twisted bilayer graphene (MATBG) has unveiled a\nrich variety of superconducting, magnetic and topologically nontrivial phases.\nThe existence of all these phases in one material, and their tunability, has\nopened new pathways for the creation of unusual gate tunable junctions.\nHowever, the required conditions for their creation - gate induced transitions\nbetween phases in zero magnetic field - have so far not been achieved. Here, we\nreport on the first experimental demonstration of a device that is both a\nzero-field Chern insulator and a superconductor. The Chern insulator occurs\nnear moire cell filling factor v = +1 in a hBN non-aligned MATBG device and\nmanifests itself via an anomalous Hall effect. The insulator has Chern number C\n= +-1 and a relatively high Curie temperature of Tc = 4.5 K. Gate tuning away\nfrom this state exposes strong superconducting phases with critical\ntemperatures of up to Tc = 3.5 K. In a perpendicular magnetic field above B >\n0.5 T we observe a transition of the /C/= +1 Chern insulator from Chern number\nC = +-1 to C = 3, characterized by a quantized Hall plateau with Ryx = h/3e2.\nThese observations show that interaction-induced symmetry breaking in MATBG\nleads to zero-field ground states that include almost degenerate and closely\ncompeting Chern insulators, and that states with larger Chern numbers couple\nmost strongly to the B-field. By providing the first demonstration of a system\nthat allows gate-induced transitions between magnetic and superconducting\nphases, our observations mark a major milestone in the creation of a new\ngeneration of quantum electronics.",
        "positive": "Epitaxial two-dimensional membranes under intrinsic and extrinsic\n  strains: Two-dimensional (2D) materials naturally form moir\\'{e} patterns with other\ncrystalline layers, such as other 2D material or the surface of a substrate.\nThese patterns add a nanoscale characteristic length in the form of a\nsuperlattice: the moir\\'{e} wavelength. Understanding the origin and\ncharacteristics of these patterns is crucial to design/interpret\nmoir\\'{e}-induced physical properties. Here, we use a mixed continuum mechanics\n+ atomistic modeling to study two experimentally relevant epitaxial 2D\nmaterials -- graphene on Ir(111) and MoS$_2$ on Au(111) -- under extrinsic and\nintrinsic strain. We consider three different scenarios affecting substantially\nthe lattice constant of the 2D materials, the wavelength and corrugation of the\nmoir\\'{e} pattern. (i) Under the influence of the interaction with the\nsubstrate, bending energy produces non trivial variations of the moir\\'{e}\nproperties, even when the strain is small; (ii) When locked on a progressively\nstrained substrate via the valleys of the moir\\'{e}, the membranes'\nnanorippling amplitude goes through several jumps related to relatively smaller\njumps in the interatomic distance of the 2D materials; (iii) Finally,\nincreasing the zero-deformation value of this interatomic distance (possibly\ncontrolable with temperature or illumination in experiments) the moir\\'{e}\nwavelength can either increase or decrease."
    },
    {
        "anchor": "Time dynamics of photothermal vs optoacoustic response in mid IR\n  nanoscale biospectroscopy: Infrared (IR) spectroscopy, a well established tool for chemical analysis of\ndiverse materials, has significant potential in biomedical applications. While\nthe spatial resolution of traditional IR spectroscopy is limited by the\nwavelength of the IR light to the few micrometres, it has been shown that\nnanoscale chemical analysis can be obtained by detecting IR induced local\nheating photothermal response via Scanning Thermal Microscopy (SThM) or local\nthermomechanical expansion using Atomic Force Microscopy (AFM). This paper\nexplores the potential of a pulsed ps pulse duration high power free electron\nlaser (FEL) light source for AFM-IR and SThM-IR spectroscopy employing standard\nAFM and SThM probes. The SThM-IR response was found to have a detrimental\nstrong background signal due to the direct heating of the probe, whereas the\nAFM IR thermomechanical response allowed to eliminate such a problem for both\ntop down and bottom up illuminations with the FEL IR source. The SThM IR\ncharacteristic response time was approximately half that of AFM-IR, in line\nwith finite element analysis simulations. Finally, the advantages and drawbacks\nof AFM-IR wavelength sensitive spectroscopic response using a ps duration FEL\nvs a high repetition quantum cascade laser IR source in studies of nanoscale\ndimension amyloid peptide fibres were explored both experimentally and via\nfinite elements analysis.",
        "positive": "Density of states, transport, and topology in disordered Majorana\n  nanowires: Motivated by a recent breakthrough transport experiment [Phys. Rev.\nB.107.245423 (2023)] in Majorana nanowires, we theoretically investigate local\nand nonlocal transport in Majorana nanowires in various disorder regimes,\ncorrelating the transport properties with the corresponding local and total\ndensity of states as well as various topological diagnostics. We find three\ndistinct disorder regimes, with weak (strong) disorder regimes manifesting (not\nmanifesting) topological superconductivity with clear end Majorana zero modes\nfor longer (but not necessarily for shorter) wires. The intermediate disorder\nregime is both interesting and challenging because the topology depends on many\ndetails in addition to the strength of disorder, such as the precise disorder\nconfiguration and the wire length. The intermediate disorder regime often\nmanifests multiple effective transitions between topological and nontopological\nphases as a function of system parameters (e.g., the Zeeman field), and is\nconsistent with the recent Microsoft experiment reflecting small topological\ngaps and narrow topological regimes in the parameter space."
    },
    {
        "anchor": "Quantum detectors for the third cumulant of current fluctuations: We consider the measurement of the third cumulant of current fluctuations\narising from a point contact, employing the transitions that they cause in a\nquantum detector connected to the contact. We detail two generic detectors: a\nquantum two-level system and a harmonic oscillator. In these systems, for an\narbitrary relation between the voltage driving the point contact and the energy\nscales of the detectors, the results can be expressed in terms of an effective\ndetector temperature T_eff. The third cumulant can be found from the dependence\nof T_eff on the sign of the driving voltage. We find that proper ordering of\nthe fluctuation operators is relevant in the analysis of the transition rates.\nThis is reflected in the effective Fano factor for the third cumulant measured\nin such setups: it depends on the ratio of the voltage and an energy scale\ndescribing the circuit where the fluctuations are produced.",
        "positive": "Beating in electronic transport through quantum dot based devices: Electronic transport through a two-level system driven by external electric\nfield and coupled to (magnetic or non-magnetic) electron reservoirs is\nconsidered theoretically. The basic transport characteristics such as current\nand tunnel magnetoresistance (TMR) are calculated in the weak coupling\napproximation by the use of rate equation connected with Green function\nformalism and slave-boson approach. The time dependent phenomenon is considered\nin the gradient expansion approximation. The results show that coherent beats\npattern can be observed both in current and TMR. The proposed system consisting\nof two quantum dots attached to external leads, in which the dots' levels can\nbe tuned independently, can be realized experimentally to test this well known\nphysical phenomenon. Finally, we also indicate possible practical applications\nof such device."
    },
    {
        "anchor": "Temperature Dependent Mean Free Path Spectra of Thermal Phonons Along\n  the c-axis of Graphite: Heat conduction in graphite has been studied for decades because of its\nexceptionally large thermal anisotropy. While the bulk thermal conductivities\nalong the in-plane and cross-plane directions are well known, less understood\nare the microscopic properties of the thermal phonons responsible for heat\nconduction. In particular, recent experimental and computational works indicate\nthat the average phonon mean free path (MFP) along the c-axis is considerably\nlarger than that estimated by kinetic theory, but the distribution of MFPs\nremains unknown. Here, we report the first quantitative measurements of c-axis\nphonon MFP spectra in graphite at a variety of temperatures using time-domain\nthermoreflectance measurements of graphite flakes with variable thickness. Our\nresults indicate that c-axis phonon MFPs have values of a few hundred\nnanometers at room temperature and a much narrower distribution than in\nisotropic crystals. At low temperatures, phonon scattering is dominated by\ngrain boundaries separating crystalline regions of different rotational\norientation. Our study provides important new insights into heat transport and\nphonon scattering mechanisms in graphite and other anisotropic van der Waals\nsolids.",
        "positive": "Optimal control of a cavity-mediated iSWAP gate between silicon spin\n  qubits: Semiconductor spin qubits may be coupled through a superconducting cavity to\ngenerate an entangling two-qubit gate. However, the fidelity of such an\noperation will be reduced by a variety of error mechanisms such as charge and\nmagnetic noise, phonons, cavity loss, transitions to non-qubit states and, for\nelectrons in silicon, excitation into other valley eigenstates. Here, we model\nthe effects of these error sources and the valley degree of freedom on the\nperformance of a cavity-mediated two-qubit iSWAP gate. For valley splittings\ninadequately large relative to the interdot tunnel coupling within each qubit,\nwe find that valley excitation may be a limiter to the fidelity of this\ntwo-qubit gate. In addition, we show tradeoffs between gating times and\nexposure to various error sources, identifying optimal operating regimes and\ndevice improvements that would have the greatest impact on the fidelity of the\ncavity-mediated spin iSWAP. Importantly, we find that while the impact of\ncharge noise and phonon relaxation favor operation in the regime where the\nqubits are most spin-like to reduce sensitivity to these sources of noise, the\ncombination of hyperfine noise and valley physics shifts the optimal regime to\ncharge-like qubits with stronger effective spin-photon coupling so that gate\ntimes can be made as short as possible. In this regime, the primary limitation\nis the need to avoid Landau-Zener transitions as the gate is implemented."
    },
    {
        "anchor": "Time-Loop Formalism for Irreversible Quantum Problems: Steady State\n  Transport in Junctions with Asymmetric Dynamics: Non-unitary quantum mechanics has been used in the past to study\nirreversibility, dissipation and decay in a variety of physical systems. In\nthis letter, we propose a general scheme to deal with systems governed by\nnon-Hermitian Hamiltonians. We argue that the Schwinger-Keldysh formalism gives\na natural description for those problems. To elucidate the method, we study a\nsimple model inspired by mesoscopic physics --an asymmetric junction. The\nsystem is governed by a non-Hermitian Hamiltonian which captures essential\naspects of irreversibility.",
        "positive": "Hall Viscosity and Electromagnetic Response: We show that, for Galilean invariant quantum Hall states, the Hall viscosity\nappears in the electromagnetic response at finite wave numbers q. In\nparticular, the leading q dependence of the Hall conductivity at small q\nreceives a contribution from the Hall viscosity. The coefficient of the q^2\nterm in the Hall conductivity is universal in the limit of strong magnetic\nfield."
    },
    {
        "anchor": "Quantifying the spin mixing conductance of EuO/W heterostructures by\n  spin Hall magnetoresistance experiments: The spin Hall magnetoresistance (SMR) allows to investigate the magnetic\ntextures of magnetically ordered insulators in heterostructures with normal\nmetals by magnetotransport experiments. We here report the observation of the\nSMR in in-situ prepared ferromagnetic EuO/W thin film bilayers with\nmagnetically and chemically well-defined interfaces. We characterize the\nmagnetoresistance effects utilizing angle-dependent and field-dependent\nmagnetotransport measurements as a function of temperature. Applying the\nestablished SMR model, we derive and quantify the real and imaginary parts of\nthe complex spin mixing interface conductance. We find that the imaginary part\nis by one order of magnitude larger than the real part. Both decrease with\nincreasing temperature. This reduction is in agreement with thermal\nfluctuations in the ferromagnet.",
        "positive": "Tunneling diodes under environmental effects: We examine the robustness of single-molecule tunneling diodes to\nthermal-environmental effects. The diode comprises three fragments: two\ndifferent conjugated chemical groups at the boundaries, and a saturated moiety\nin between, breaking conjugation. In this setup, molecular electronic levels\nlocalized on the conjugated groups independently shift with applied bias. While\nin the forward polarity a resonance condition is met, enhancing conductance, in\nthe reversed direction molecular electronic states shift away from each other,\nresulting in small tunneling currents. In the absence of interactions with a\nthermal environment (consisting e.g. internal vibrations, solvent),\nrectification ratios reach three orders of magnitude. We introduce decoherence\nand inelastic-dissipative effects phenomenologically, by using the \"voltage\nprobe\" approach. We find that when $\\gamma_d \\lesssim v$, with $\\gamma_d$ the\ninteraction energy of electrons with the environment and $v$ the tunneling\nenergy across the saturated link, the diode is still highly effective, though\nrectification ratios are cut down by a factor of 2-4 compared to the coherent\nlimit. To further enhance rectification ratios in molecular diodes we suggest a\nrefined design involving four orbitals, with a pair of closely spaced states at\neach conjugated moiety."
    },
    {
        "anchor": "Pauli Blockade of Tunable Two-Electron Spin and Valley States in\n  Graphene Quantum Dots: Pauli blockade mechanisms -- whereby carrier transport through quantum dots\nis blocked due to selection rules even when energetically allowed -- are a\ndirect manifestation of the Pauli exclusion principle, as well as a key\nmechanism for manipulating and reading out spin qubits. Pauli spin blockade is\nwell established for systems such as GaAs QDs, but is to be further explored\nfor systems with additional degrees of freedom, such as the valley quantum\nnumbers in carbon-based materials or silicon. Here we report experiments on\ncoupled bilayer graphene double quantum dots, in which the spin and valley\nstates are precisely controlled, enabling the observation of the two-electron\ncombined blockade physics. We demonstrate that the doubly occupied single dot\nswitches between two different ground states with gate and magnetic-field\ntuning, allowing for the switching of selection rules: with a\nspin-triplet--valley-singlet ground state, valley-blockade is observed; and\nwith the spin-singlet--valley-triplet ground state, robust spin blockade is\nshown.",
        "positive": "Negative quantum capacitance in graphene nanoribbons with lateral gates: We present numerical simulations of the capacitive coupling between graphene\nnanoribbons of various widths and gate electrodes in different configurations.\nWe compare the influence of lateral metallic or graphene side gate structures\non the overall back gate capacitive coupling. Most interestingly, we find a\ncomplex interplay between quantum capacitance effects in the graphene\nnanoribbon and the lateral graphene side gates, giving rise to an\nunconventional negative quantum capacitance. The emerging non-linear capacitive\ncouplings are investigated in detail. The experimentally relevant relative\nlever arm, the ratio between the coupling of the different gate structures, is\ndiscussed."
    },
    {
        "anchor": "Tunable correlation-driven symmetry breaking in twisted double bilayer\n  graphene: A variety of correlated phases have recently emerged in select twisted van\nder Waals (vdW) heterostructures owing to their flat electronic dispersions. In\nparticular, heterostructures of twisted double bilayer graphene (tDBG) manifest\nelectric field-tunable correlated insulating (CI) states at all quarter\nfillings of the conduction band, accompanied by nearby states featuring\nsignatures suggestive of superconductivity. Here, we report electrical\ntransport measurements of tDBG in which we elucidate the fundamental role of\nspontaneous symmetry breaking within its correlated phase diagram. We observe\nabrupt resistivity drops upon lowering the temperature in the correlated\nmetallic phases neighboring the CI states, along with associated nonlinear\n$I$-$V$ characteristics. Despite qualitative similarities to superconductivity,\nconcomitant reversals in the sign of the Hall coefficient instead point to\nspontaneous symmetry breaking as the origin of the abrupt resistivity drops,\nwhile Joule heating appears to underlie the nonlinear transport. Our results\nsuggest that similar mechanisms are likely relevant across a broader class of\nsemiconducting flat band vdW heterostructures.",
        "positive": "Nontrivial band geometry in an optically active system: Optical activity (OA), also called circular birefringence, is known for two\nhundred years, but its applications for topological photonics remain\nunexplored. Unlike the Faraday effect, OA provokes rotation of the linear\npolarization of light without magnetic effects, thus preserving the\ntime-reversal symmetry. Here, we report a direct measurement of the Berry\ncurvature and quantum metric of the photonic modes of a planar cavity\ncontaining an optically active organic microcrystal (perylene). Photonic\nspin-orbit-coupling induced by the cavity results in the action of a\nnon-Abelian gauge field on photons. The addition of high OA makes emerge\ngeometrically non-trivial bands containing two gapped Dirac cones with opposite\ntopological charges. This experiment performed at room temperature and at\nvisible wavelength establishes the potential of optically active organic\nmaterials for implementing non-magnetic and low-cost topological photonic\ndevices."
    },
    {
        "anchor": "Quantum plateaus in dynamical Hall conductivity: Dynamical Hall conductivity {\\sigma}_H({\\omega}) of a 2D electron gas with\nimpurities in the perpendicular magnetic field is analyzed. Plateau-like\nbehavior at low frequencies as well as at high frequencies provided the\ncomplete filling of Landau levels is predicted. The broadening of a Landau\nlevel separates two frequency regions with different behaviour. Imaginary part\nof dynamical Hall conductivity reveals oscillations in the localized states\nregion. Comparison with the experiment is carried out.",
        "positive": "Vortex arrays in a rotating superfluid He-4 nanocylinder: Within Density Functional theory, we investigate stationary many-vortex\nstructures in a rotating $^4$He nanocylinder at zero temperature. We compute\nthe stability diagram and compare our results with the classical model of\nvortical lines in an inviscid and incompressible fluid. Scaling the results to\nmillimeter-size buckets, they can be compared with experiments on vortex arrays\nconducted in the past. Motivated by recent experiments that have used atomic\nimpurities as a means of visualizing vortices in superfluid $^4$He droplets, we\nhave also considered the formation of chains of xenon atoms along a vortex line\nand the interaction between xenon atoms inside the same vortex and on different\nneighboring vortex lines."
    },
    {
        "anchor": "$n$-Hourglass Weyl fermions in nonsymmorphic materials: Hourglass-like band structures protected by nonsymmorphic space group\nsymmetries can appear along high-symmetry lines or in high-symmetry surfaces in\nthe Brillouin zone. In this work, from symmetry analysis, we demonstrate that\n$n$-hourglass-like band structures, a generalization of hourglass-like band\nstructures, which host a number of Weyl points, are enforced along\nscrew-invariant lines in non-magnetic materials with a single $N$-fold screw\naxis when spin-orbit coupling is finite, where $n$, a non-unity factor of $N$,\ndenotes the degree of the screw-invariant line. The \"standard\" $n$-hourglass\nhas $n-1$ crossings, which is minimal, and its variants can have more\ncrossings. Purely by symmetry considerations, we find there are minimally two\nparticle and two hole Fermi pockets enclosing Weyl points with opposite\nmonopole charges at proper fillings, which can result in distinct physical\neffects including the possible formation of topological density waves and the\nquantum nonlinear Hall effect. We construct a minimal model which respects all\nthe symmetries, and from which we see how the $n$-hourglasses appear when\nspin-orbit coupling is turned on. The same results are derived from\ncompatibility relations. As exemplary, BiPd, ZnTe under high pressure, and the\nhigh-temperature phase of Tl$_3$PbBr$_5$, are shown from first-principles\ncalculations to exhibit $n$-hourglass-like band structures, with $N=2,3,4$,\nrespectively, which confirms our symmetry analysis and minimal model.",
        "positive": "Absorption, Photoluminescence and Resonant Rayleigh Scattering Probes of\n  Condensed Microcavity Polaritons: We investigate and compare different optical probes of a condensed state of\nmicrocavity polaritons in expected experimental conditions of non-resonant\npumping. We show that the energy- and momentum-resolved resonant Rayleigh\nsignal provide a distinctive probe of condensation as compared to, e.g.,\nphotoluminescence emission. In particular, the presence of a collective sound\nmode both above and below the chemical potential can be observed, as well as\nfeatures directly related to the density of states of particle-hole like\nexcitations. Both resonant Rayleigh response and the absorption and\nphotoluminescence, are affected by the presence of quantum well disorder, which\nintroduces a distribution of oscillator strengths between quantum well excitons\nat a given energy and cavity photons at a given momentum. As we show, this\ndistribution makes it important that in the condensed regime, scattering by\ndisorder is taken into account to all orders. We show that, in the low density\nlinear limit, this approach correctly describes inhomogeneous broadening of\npolaritons. In addition, in this limit, we extract a linear blue-shift of the\nlower polariton versus density, with a coefficient determined by temperature\nand by a characteristic disorder length."
    },
    {
        "anchor": "Donor Spin Qubits in Ge-based Phononic Crystals: We propose qubits based on shallow donor electron spins in germanium.\nSpin-orbit interaction for donor spins in germanium is in many orders of\nmagnitude stronger than in silicon. In a uniform bulk material it leads to very\nshort spin lifetimes. However the lifetime increases dramatically when the\ndonor is placed into a quasi-2D phononic crystal and the energy of the Zeeman\nsplitting is tuned to lie within a phonon bandgap. In this situation single\nphonon processes are suppressed by energy conservation. The remaining\ntwo-phonon decay channel is very slow. The Zeeman splitting within the gap can\nbe fine tuned to induce a strong, long-range coupling between the spins of\nremote donors via exchange by virtual phonons. This, in turn, opens a very\nefficient way to manipulate the quits. We explore various geometries of\nphononic crystals in order to maximize the coherent qubit-qubit coupling while\nkeeping the decay rate minimal. We find that phononic crystals with unit cell\nsizes of 100-150 nm are viable candidates for quantum computing applications\nand suggest several spin-resonance experiments to verify our theoretical\npredictions.",
        "positive": "Temporal evolution of auto-oscillations in a YIG/Pt microdisc driven by\n  pulsed spin Hall effect-induced spin-transfer torque: The temporal evolution of pulsed Spin Hall Effect - Spin Transfer Torque\n(SHE-STT) driven auto-oscillations in a Yttrium Iron Garnet (YIG) / platinum\n(Pt) microdisc is studied experimentally using time-resolved Brillouin Light\nScattering (BLS) spectroscopy. It is demonstrated that the frequency of the\nauto-oscillations is different in the center and at the edge of the\ninvestigated disc that is related to the simultaneous STT excitation of a\nbullet and a non-localized spin-wave mode. Furthermore, the magnetization\nprecession intensity is found to saturate on a time scale of 20 ns or longer,\ndepending on the current density. For this reason, our findings suggest that a\nproper ratio between the current and the pulse duration is of crucial\nimportance for future STT-based devices."
    },
    {
        "anchor": "Theory of parametric amplification in in superlattices: We consider a high-frequency response of electrons in a single miniband of\nsuperlattice subject to dc and ac electric fields. We show that Bragg\nreflections in miniband result in a parametric resonance which is detectable\nusing ac probe field. We establish theoretical feasibility of phase-sensitive\nTHz amplification at the resonance. The parametric amplification does not\nrequire operation in conditions of negative differential conductance. This\nprevents a formation of destructive high-field domains inside the superlattice.",
        "positive": "The 30-band k.p modeling of electron and hole states in silicon quantum\n  wells: We modeled the electron and hole states in Si/SiO2 quantum wells within a\nbasis of standing waves using the 30-band k.p theory. The hard-wall confinement\npotential is assumed, and the influence of the peculiar band structure of bulk\nsilicon on the quantum-well sub-bands is explored. Numerous spurious solutions\nin the conduction-band and valence-band energy spectra are found and are\nidentified to be of two types: (1) spurious states which have large\ncontributions of the bulk solutions with large wave-vectors (the high-k\nspurious solutions) and (2) states which originate mainly from the spurious\nvalley outside the Brillouin zone (the extra-valley spurious solutions). An\nalgorithm to remove all those nonphysical solutions from the electron and hole\nenergy spectra is proposed. Furthermore, slow and oscillatory convergence of\nthe hole energy levels with the number of basis functions is found and is\nexplained by the peculiar band mixing and the confinement in the considered\nquantum well. We discovered that assuming the hard-wall potential leads to\nnumerical instability of the hole states computation. Nonetheless, allowing the\nenvelope functions to exponentially decay in a barrier of finite height is\nfound to improve the accuracy of the computed hole states."
    },
    {
        "anchor": "Magnetization dynamics in the inertial regime: nutation predicted at\n  short time scales: The dynamical equation of the magnetization has been reconsidered with\nenlarging the phase space of the ferromagnetic degrees of freedom to the\nangular momentum. The generalized Landau-Lifshitz-Gilbert equation that\nincludes inertial terms, and the corresponding Fokker-Planck equation, are then\nderived in the framework of mesoscopic non-equilibrium thermodynamics theory. A\ntypical relaxation time $\\tau$ is introduced describing the relaxation of the\nmagnetization acceleration from the inertial regime towards the precession\nregime defined by a constant Larmor frequency. For time scales larger than\n$\\tau$, the usual Gilbert equation is recovered. For time scales below $\\tau$,\nnutation and related inertial effects are predicted. The inertial regime offers\nnew opportunities for the implementation of ultrafast magnetization switching\nin magnetic devices.",
        "positive": "Imaging the nanoscale phase separation in vanadium dioxide thin films at\n  terahertz frequencies: We use apertureless scattering near-field optical microscopy (SNOM) to\ninvestigate the nanoscale optical response of vanadium dioxide (VO2) thin films\nthrough a temperature-induced insulator-to-metal transition (IMT). We compare\nimages of the transition at both mid-infrared (MIR) and terahertz (THz)\nfrequencies, using a custom-built broadband THz-SNOM compatible with both\ncryogenic and elevated temperatures. We observe that the character of spatial\ninhomogeneities in the VO2 film strongly depends on the probing frequency. In\naddition, we find that individual insulating (or metallic) domains have a\ntemperature-dependent optical response, in contrast to the assumptions of a\nclassical first-order phase transition. We discuss these results in light of\ndynamical mean-field theory calculations of the dimer Hubbard model recently\napplied to VO2."
    },
    {
        "anchor": "Cotunneling thermopower of single electron transistors: We study the thermopower of a quantum dot weakly coupled to two reservoirs by\ntunnel junctions. At low temperatures the transport through the dot is\nsuppressed by charging effects (Coulomb blockade). As a result the thermopower\nshows an oscillatory dependence on the gate voltage. We study this dependence\nin the limit of low temperatures where the transport through the dot is\ndominated by the processes of inelastic cotunneling. We also obtain a crossover\nformula for intermediate temperatures which connects our cotunneling results to\nthe known sawtooth behavior in the sequential tunneling regime. As the\ntemperature is lowered, the amplitude of thermopower oscillations increases,\nand their shape changes qualitatively.",
        "positive": "Resources of nonlinear cavity magnonics for quantum information: We theoretically explore nonlinearities of ferromagnets in microwave cavities\nin the classical and quantum regimes, and assess the resources for quantum\ninformation, i.e. fluctuation squeezing and bipartite entanglement. The\n(semi-)classical analysis of the anharmonic oscillator (Duffing) model for the\nKittel mode when including all other magnon modes, reveals chaotic and\nlimit-cycle phases that do not survive in quantum calculations. However,\nmagnons with nonzero wavenumbers that are driven by the Suhl instability of the\nKittel mode, form a genuine limit cycle. We subsequently compute bounds for the\ndistillable entanglement, as well as entanglement of formation for the\nbipartite configurations of the mixed magnon modes. The distillable\nentanglement of bipartite states accessible from a covariance matrix vanishes,\nbut can be recovered by injection locking. The predicted magnon entanglement\ncan be experimentally tested with yttrium iron garnet samples under realistic\nconditions."
    },
    {
        "anchor": "Unified characterization for higher-order topological phase transitions: Higher-order topological phase transitions (HOTPTs) are associated with\nclosing either the bulk energy gap (type-I) or boundary energy gap (type-II)\nwithout changing symmetry, and conventionally the both transitions are captured\nin real space and characterized separately. Here we propose a momentum-space\ntopological characterization of the HOTPTs, which unifies the both types of\ntopological transitions and enables a precise detection by quench dynamics. Our\nunified characterization is based on a novel correspondence between the mass\ndomain walls on real-space boundaries and the higher-order band-inversion\nsurfaces (BIS) which are characteristic interfaces in the momentum subspace.\nThe topological transitions occur when momentum-space topological nodes, dubbed\nhigher-order topological charges, cross the higher-order BISs after proper\nprojection. Particularly, the bulk (boundary) gap closes when all (part of)\ntopological charges cross the BISs, characterizing the type-I (type-II) HOTPTs.\nThese distinct dynamical behaviours of higher-order topological charges can be\nfeasibly measured from quench dynamics driven with control in experiments. Our\nwork opens an avenue to characterize and detect the two types of HOTPTs within\na unified framework, and shall advance the research in both theory and\nexperiment.",
        "positive": "Non-Wigner-Dyson level statistics and fractal wavefunction of disordered\n  Weyl semimetals: Finding fingerprints of disordered Weyl semimetals (WSMs) is an unsolved\ntask. Here we report such findings in the level statistics and the fractal\nnature of electron wavefunction around Weyl nodes of disordered WSMs. The\nnearest-neighbor level spacing follows a new universal distribution $P_c(s)=C_1\ns^2\\exp[-C_2 s^{2-\\gamma_0}]$ originally proposed for the level statistics of\ncritical states in the integer quantum Hall systems or normal dirty metals\n(diffusive metals) at metal-to-insulator transitions, instead of the\nWigner-Dyson distribution for diffusive metals. Numerically, we find\n$\\gamma_0=0.62\\pm0.07$. In contrast to the Bloch wavefuntions of clean WSMs\nthat uniformly distribute over the whole space of ($D=3$) at large length\nscale, the wavefunction of disordered WSMs at a Weyl node occupies a fractal\nspace of dimension $D=2.18\\pm 0.05$. The finite size scaling of the inverse\nparticipation ratio suggests that the correlation length of wavefunctions at\nWeyl nodes ($E=0$) diverges as $\\xi\\propto |E|^{-\\nu}$ with $\\nu=0.89\\pm0.05$.\nIn the ergodic limit,the level number variance $\\Sigma_2$ around Weyl nodes\nincreases linearly with the average level number $N$, $\\Sigma_2=\\chi N$, where\n$\\chi= 0.2\\pm0.1$ is independent of system sizes and disorder strengths."
    },
    {
        "anchor": "Detecting Majorana modes by readout of poisoning-induced parity flips: Reading out the parity degree of freedom of Majorana bound states is key to\ndemonstrating their nonabelian exchange properties. Here, we present a\nlow-energy model describing localized edge states in a two-arm device. We study\nparity-to-charge conversion based on coupling the superconductor bound states\nto a quantum dot whose charge is read out by a sensor. The dynamics of the\nsystem, including the readout device, is analyzed in full using a quantum-jump\napproach. We show how the resulting signal and noise ratio differentiates\nbetween local Majorana and Andreev bound states.",
        "positive": "Multiphoton processes in microwave photoresistance of 2D electron system: We extend our studies of microwave photoresistance of ultra-high mobility\ntwo-dimensional electron system (2DES) into the high-intensity, non-linear\nregime employing both monochromatic and bichromatic radiation. Under\nhigh-intensity monochromatic radiation $\\omega$ we observe new zero-resistance\nstates (ZRS) which correspond to rational values of $\\epsilon=\\omega/\\omega_C$\n($\\omega_C$ is the cyclotron frequency) and can be associated with multiphoton\nprocesses. %Formation of these rational ZRS is accompanied by a dramatic\nreconstruction of the photoresistance spectrum which reveals diminishing,\nnarrowing, and phase reduction of the resistance peaks, as well as overall\nsuppression of resistance at $\\epsilon<1/2$. Under bichromatic radiation\n$\\omega_1,\\omega_2$ we discover new resistance minimum, possibly a precursor of\nbichromatic ZRS, which seems to originate from a frequency mixing process,\n$\\omega_1+\\omega_2$. These findings indicate that multiphoton processes play\nimportant roles in the physics of non-equilibrium transport of microwave-driven\n2DES, and suggest new directions for theoretical and experimental studies."
    },
    {
        "anchor": "A resolution of the problem of additional boundary conditions: Maxwell's boundary conditions (MBCs) were long known insufficient to\ndetermine the optical responses of spatially dispersive medium. Supplementing\nMBCs with additional boundary conditions (ABCs) has become a normal yet\ncontroversial practice. Here the problem of ABCs is solved by analyzing some\nsubtle aspects of a physical surface. A generic theory is presented for\nhandling the interaction of light with the surfaces of an arbitrary medium and\napplied to study the traditional problem of exciton polaritons. We show that\nABCs can always be adjusted to fit the theory but they can by no means be\nconstrued as intrinsic surface characteristics, which are instead captured by a\n\\textit{surface response function} (SRF). Unlike any ABCs, a SRF describes\nessentially non-local boundary effects. Methods for experimentally extracting\nthe spatial profile of this function are proposed.",
        "positive": "Two-body Wigner molecularization in asymmetric quantum dot spin qubits: Coulomb interactions strongly influence the spectrum and the wave functions\nof few electrons or holes confined in a quantum dot. In particular, when the\nconfinement potential is not too strong, the Coulomb repulsion triggers the\nformation of a correlated state, the Wigner molecule, where the particles tend\nto split apart. We show that the anisotropy of the confinement potential\nstrongly enhances the molecularization process and affects the performances of\nquantum-dot systems used as spin qubits. Relying on analytical and numerical\nsolutions of the two-particle problem -- both in a simplified single-band\napproximation and in realistic setups -- we highlight the exponential\nsuppression of the singlet-triplet gap with increasing anisotropy. We compare\nthe molecularization effects in different semiconductor materials and discuss\nhow they specifically hamper Pauli spin blockade readout and reduce the\nexchange interactions in two-qubit gates."
    },
    {
        "anchor": "Metallic State of Low Mobility Silicon at High Carrier density induced\n  by an Ionic Liquid: High mobility and dilute two-dimensional electron systems exhibit metallic\nbehavior down to the lowest experimental temperatures. In studies of ionic\nliquid gated insulating silicon, we have observed transitions to a metallic\nstate in low mobility samples at much higher areal carrier densities than found\nfor samples of high mobility. We have also observed a mobility peak in metallic\nsamples as the carrier density was increased beyond $10^{13} \\text{cm}^{-2}$.",
        "positive": "Efficient orbital angular momentum transfer between plasmons and free\n  electrons: Free electrons can efficiently absorb or emit plasmons excited in a thin\nconductor, giving rise to multiple energy peaks in the transmitted electron\nspectra separated by multiples of the plasmon energy. When the plasmons are\nchiral, this can also give rise to transfer of orbital angular momentum (OAM).\nHere, we show that large amounts of OAM can be efficiently transferred between\nchiral plasmons supported by a thin film and free electrons traversing it.\nUnder realistic conditions, our predictive simulations reveal efficient\nabsorption of $\\ell\\gg1$ chiral plasmons of vorticity $m\\gg1$, resulting in an\nOAM transfer $\\ell m\\hbar\\gg\\hbar$. Our work supports the use of chiral\nplasmons sustained by externally illuminated thin films as a way of generating\nhigh-vorticity electrons, resulting in a remarkably large fraction of kinetic\nenergy associated with motion along the azimuthal direction, perpendicular to\nthe incident beam."
    },
    {
        "anchor": "Emission and Absorption quantum noise measurement with an on-chip\n  resonant circuit: Using a quantum detector, a superconductor-insulator-superconductor junction,\nwe probe separately the emission and absorption noise in the quantum regime of\na superconducting resonant circuit at equilibrium. At low temperature the\nresonant circuit exhibits only absorption noise related to zero point\nfluctuations whereas at higher temperature emission noise is also present. By\ncoupling a Josephson junction, biased above the superconducting gap, to the\nsame resonant circuit, we directly measure the noise power of quasiparticles\ntunneling through the junction at two resonance frequencies. It exhibits a\nstrong frequency dependence, consistent with theoretical predictions.",
        "positive": "Resonant magneto-conductance through a vibrating nanotube: We address the electronic resonant transport in presence of a transverse\nmagnetic field through the single level of a suspended carbon nanotube acting\nas a quantum oscillator. We predict a negative magneto-conductance with a\nmagnetic-field induced narrowing of the resonance line and a reduction of the\nconductance peak when the nanotube is asymmetrically contacted to the leads. At\nfinite bias voltage we study the threshold for phonon-assisted transport."
    },
    {
        "anchor": "Symmetry Content and Observation of Charged Collective Excitations for\n  Graphene in Strong Magnetic Fields: We show that graphene in a strong magnetic field with partially filled Landau\nlevels sustains charged collective excitations, which are bound states of\nthree-particle complexes. Some of these states are optically bright and may be\ndetected in spectroscopy experiments, enhancing the current understanding of\nelectron-electron interactions in graphene. The states can be classified using\nthe geometrical symmetries - non-commutative magnetic translations and\ngeneralized rotations - in addition to the dynamical SU(4) symmetry in\ngraphene. From the SU(4) symmetry point of view, such excitations are analogous\nto bound states of two quarks and one antiquark qqqbar with four flavors. We\nestablish a flavor optical selection rule to identify the bright states for\nexperimental studies.",
        "positive": "Microscopic theory of the polarizability of transition metal\n  dichalcogenides excitons: Application to WSe2: In this paper we develop a fully microscopic theory of the polarizability of\nexcitons in transition metal dichalcogenides. We apply our method to the\ndescription of the excitation $2$p dark states. These states are not observable\nin absorption experiments but can be excited in a pump-probe experiment. As an\nexample we consider $2$p dark states in WSe\\textsubscript{2}. We find a good\nagreement between recent experimental measurements and our theoretical\ncalculations."
    },
    {
        "anchor": "Long-lived discrete breathers in free-standing graphene: Intrinsic localized modes or discrete breathers are investigated by molecular\ndynamics simulations in free-standing graphene. Discrete breathers are\ngenerated either through thermal quenching of the graphene lattice or by proper\ninitialization, with frequencies and lifetimes sensitively depending on the\ninteratomic potential describing the carbon-carbon interaction. In the most\nrealistic scenario, for which temperature-dependent molecular dynamics\nsimulations in three dimension using a graphene-specific interatomic potential\nare performed, the breather lifetimes increase to hundreds of picoseconds even\nat relatively high temperatures. These lifetimes are much higher than those\nanticipated from earlier calculations, and may enable direct breather\nobservation in Raman spectroscopy experiments.",
        "positive": "Quasinormal mode theory and modelling of electron energy loss\n  spectroscopy for plasmonic nanostructures: Understanding light-matter interactions using localized surface plasmons\n(LSPs) is of fundamental interest in classical and quantum plasmonics and has a\nwide range of applications. In order to understand the spatial properties of\nLSPs, electron energy loss spectroscopy (EELS) is a common and powerful method\nof spatially resolving the extreme localized fields that can be obtained with\nmetal resonators. However, modelling EELS for general shaped resonators\npresents a major challenge in computational electrodynamics, requiring the full\nphoton Green function as a function of two space points and frequency. Here we\npresent an intuitive and computationally simple method for computing EELS maps\nof plasmonic resonators using a quasinormal mode (QNM) expansion technique. By\nseparating the contribution of the QNM and the bulk material, we give\nclosed-form analytical formulas for the plasmonic QNM contribution to the EELS\nmaps. We exemplify our technique for a split ring resonator, a gold nanorod,\nand a nanorod dimer structure. The method is accurate, intuitive, and gives\norders of magnitude improvements over direct dipole simulations that\nnumerically solve the full 3D Maxwell equations. We also show how the same QNM\nGreen function can be used to obtain the Purcell factor (and projected local\ndensity of optical states) from quantum dipole emitters or two level atoms, and\nwe demonstrate how the spectral features differ in general to the EELS\nspectrum."
    },
    {
        "anchor": "Impurity bound states as detectors of topological band structures\n  revisited: Band structures of topological insulators are characterized by non-local\ntopological invariants. Consequently, proposals for the experimental detection\nusing local probes are rare. A recent paper [Slager et al., Phys. Rev. B 92,\n085126 (2015)] has argued, based on theoretical results for a particular class\nof models, that insulators with topologically trivial and non-trivial band\nstructures in two space dimensions display a qualitatively different response\nto point-like impurities. Here we present a comprehensive investigation of the\nimpurity response of a large set of models of non-interacting electrons on the\nhoneycomb lattice, driven insulating by either broken inversion, broken time\nreversal, broken $C_3$, or broken translation symmetry. These cases include\nHofstadter bands, strain-induced pseudo-Landau levels and higher-order\ntopological insulators. Our results confirm that for hopping models respecting\nthe lattice symmetries, the response to a single impurity can indeed\ndistinguish between trivial and non-trivial band topology. However, for\nmodulated or inhomogeneous host systems we find that trivial states of matter\ncan display an impurity response akin to that of topologically non-trivial\nstates, and thus the diagnostic fails.",
        "positive": "Majorana nanowires, Kitaev chains, and spin models: Motivated by the fact that the idealized Kitaev chain toy model and the\nexperimental semiconductor-superconductor Majorana nanowire can both host the\nMajorana zero modes, we theoretically investigate the question to what extent\nthe two models are equivalent or similar, using the perspective of the\ncorresponding dual spin models for both. We start with the duality between the\nKitaev chain and the transverse-field XY spin model through the Jordan-Wigner\ntransformation with the goal of establishing the connection between the Kitaev\nchain and the nanowire. By applying the Jordan-Wigner transformation to the\nnanowire, we find that the corresponding bosonic spin model is a generalized\nspin cluster model, containing 3-spin and 4-spin terms, with staggered\ncouplings. By projecting out the upper band of the bare semiconductor with\nhigher energy, we obtain an effective low-energy spinless system from the\nspinful nanowire system deep in the topological regime. Finally, we establish\nthe connection between the Kitaev chain and Majorana nanowire by showing that\nthe spinless Kitaev chain can be viewed as the first-order approximation of the\nspinful Majorana nanowire deep in the topological regime."
    },
    {
        "anchor": "Fluorescence thermometry enhanced by the quantum coherence of single\n  spins in diamond: We demonstrate fluorescence thermometry techniques with sensitivities\napproaching 10 mK Hz^(-1/2) based on the spin-dependent photoluminescence of\nnitrogen vacancy (NV) centers in diamond. These techniques use dynamical\ndecoupling protocols to convert thermally induced shifts in the NV center's\nspin resonance frequencies into large changes in its fluorescence. By\nmitigating interactions with nearby nuclear spins and facilitating selective\nthermal measurements, these protocols enhance the spin coherence times\naccessible for thermometry by 45x, corresponding to a 7x improvement in the NV\ncenter's temperature sensitivity. Moreover, we demonstrate these techniques can\nbe applied over a broad temperature range and in both finite and near-zero\nmagnetic field environments. This versatility suggests that the quantum\ncoherence of single spins could be practically leveraged for sensitive\nthermometry in a wide variety of biological and microscale systems.",
        "positive": "Topological junction states and their crystalline network in\n  chiral-symmetric systems: application to graphene nanoribbons: We develop a general theoretical framework based on $Z$-classification to\ncount the number of topological bound states at a junction of chiral-symmetric\none-dimensional systems. The formulation applies to general multiway junctions\ncomposed of an arbitrary number of channels and an arbitrary joint structure.\nBy using the formula, we calculate the zero-energy bound states in various\ntypes of two-way and three-way junctions of semiconducting graphene\nnanoribbons. We then consider periodic two-dimensional networks of graphene\nnanoribbons, and show that the topological junction states form isolated energy\nbands inside the bulk energy gap, which can be viewed as a two-dimensional\ncrystal of the effective atoms. Depending on the $Z$ number of a single\njunction, we have a different set of effective atomic orbitals, resulting in\nvarious types of nanoscale metamaterials, which are often accompanied by flat\nbands. The system would provide an ideal platform for quantum simulator to\nemulate a strongly-interacting fermion system on various types of lattices."
    },
    {
        "anchor": "Manifestation of a topological gapless phase in a two-dimensional chiral\n  symmetric system through Loschmidt echo: Unlike the edge state of a topological insulator where its energy level lives\nin the bulk energy gap, the edge state of a topological semimetal hides in the\nbulk spectrum and is difficult to be identified by the energy. We investigate\nthe sensitivity of bulk and edge states of the gapless phase for a topological\nsemimetal to the disordered perturbation via a concrete two-dimensional chiral\nsymmetric lattice model. The topological gapless phase is characterized by two\nopposite vortices in the momentum space and nonzero winding numbers, which\ncorrespond to the edge flatband when the open boundary condition is applied.\nFor this system, numerical results reveal that a distinguishing feature is that\nthe robustness of the edge states against weak disorder and the flatband edge\nmodes remain locked at zero energy in the presence of weak\nchiral-symmetry-preserving disorder. We employ the Loschmidt echo (LE) for both\nbulk and edge states to study the dynamic effect of disordered perturbation. We\nshow that, for an initial bulk state, the LE decays exponentially, whereas it\nconverges to a constant for an initial edge state in the presence of weak\ndisorder. Furthermore, the convergent LE can be utilized to identify the\npositions of vortices as well as the phase diagram. We discuss the realization\nof such dynamic investigations in a topological photonic system.",
        "positive": "Electrically Reconfigurable Optical Metamaterial Based on Colloidal\n  Dispersion of Metal Nano-Rods in Dielectric Fluid: Optical metamaterials capture the imagination with breathtaking promises of\nnanoscale resolution in imaging and invisibility cloaking. We demonstrate an\napproach to construct a metamaterial in which metallic nanorods, of dimension\nmuch smaller than the wavelength of light, are suspended in a fluid and placed\nin a nonuniform electric field. The field controls the spatial distribution and\norientation of nanorods because of the dielectrophoretic effect. The\nfield-controlled placement of nanorods causes optical effects such as varying\nrefractive index, optical anisotropy (birefringence), and reduced visibility of\nan object enclosed by the metamaterial."
    },
    {
        "anchor": "From Coulomb blockade to nonlinear quantum dynamics in a superconducting\n  circuit with a resonator: Motivated by recent experiments on superconducting circuits consisting of a\ndc-voltage biased Josephson junction in series with a resonator, quantum\nproperties of these devices far from equilibrium are studied. This includes a\ncrossover from a domain of incoherent to a domain of coherent Cooper pair\ntunneling, where the circuit realizes a driven nonlinear oscillator.\nEquivalently, weak photon-charge coupling turns into strong correlations\ncaptured by a single degree of freedom. Radiated photons offer a new tool to\nmonitor charge flow and current noise gives access to nonlinear dynamics, which\nallows to analyze quantum-classical boundaries.",
        "positive": "Suppression of the Coulomb interaction contribution to the conductance\n  by a parallel magnetic field: The Coulomb interaction contribution to the conductance is investigated in a\nphase-coherent disordered 2-dimensional electron gas, which resistance can be\nvaried by an overall gate electrode. Its magnitude of dGeei=-0.3 e^2/h is\nobtained by applying a bias voltage to suppress the Coulomb anomaly. In\ncontrast to theoretical predictions, dGeei is suppressed by a parallel magnetic\nfield. The zero-bias magnetoresistance exhibits reproducible fluctuations in\nperpendicular magnetic fields on a field scale much larger than that expected\nfor universal conductance fluctuations, which might be attributed to\nfluctuations in the Coulomb interaction contribution."
    },
    {
        "anchor": "On the radiative lifetime of free-moving two-dimensional excitons: A simple microscopic mechanism explaining the linear dependence of the\nradiative lifetime of free-moving two-dimensional excitons on their effective\ntemperature is suggested. It is shown that there exists a characteristic\neffective temperature (of about few Kelvin) defined by the exciton-acoustic\nphonon interaction at which the radiative lifetime is minimal. Below this\ntemperature the lifetime starts to increase with decreasing temperature. The\ncorrespondence with previous theoretical and experimental results is discussed.",
        "positive": "Berry Curvature in Graphene: A New Approach: In the present paper we have directly computed the Berry curvature terms\nrelevant for Graphene in the presence of an \\textit{inhomogeneous} lattice\ndistortion. We have employed the generalized Foldy Wouthuysen framework,\ndeveloped by some of us \\cite{ber0,ber1,ber2}. We show that a non-constant\nlattice distortion leads to a valley-orbit coupling which is responsible to a\nvalley-Hall effect. This is similar to the valley-Hall effect induced by an\nelectric field proposed in \\cite{niu2} and is the analogue of the spin-Hall\neffect in semiconductors \\cite{MURAKAMI, SINOVA}. Our general expressions for\nBerry curvature, for the special case of homogeneous distortion, reduce to the\npreviously obtained results \\cite{niu2}. We also discuss the Berry phase in the\nquantization of cyclotron motion."
    },
    {
        "anchor": "Spin-orbit correlations and exchange-bias control in twisted Janus\n  dichalcogenide multilayers: Janus dichalcogenide multilayers provide a paradigmatic platform to engineer\nelectronic phenomena dominated by spin-orbit coupling. Their unique spin-orbit\neffects stem from local mirror symmetry breaking in each layer, which induces a\ncolossal Rashba spin-orbit effect in comparison with the conventional\ndichalcogenide counterparts. Here we put forward twisted dichalcogenide\nbilayers as a simple platform to realize spin-orbit correlated states. We\ndemonstrate the emergence of flat bands featuring strong spin-momentum locking\nand the emergence of non-collinear symmetry broken states when interactions are\nincluded. We further show that the symmetry broken states can be controlled by\nmeans of a magnetic substrate, strongly impacting the non-collinear magnetic\ntexture of the moire unit cell. Our results put forward twisted Janus\nmultilayers as a powerful platform to explore spin-orbit correlated physics,\nand highlighting the versatility of magnetic substrates to control\nunconventional moire magnetism.",
        "positive": "Small mode volume topological photonic states in one-dimensional\n  lattices with dipole--quadrupole interactions: We study the topological photonic states in one-dimensional (1-D) lattices\nanalogue to the Su-Schrieffer-Heeger (SSH) model beyond the dipole\napproximation. The electromagnetic resonances of the lattices supported by\nnear-field interactions between the plasmonic nanoparticles are studied\nanalytically with coupled dipole--quadrupole method. The topological phase\ntransition in the bipartite lattices is determined by the change of Zak phase.\nOur results reveal the contribution of quadrupole moments to the near-field\ninteractions and the band topology. It is found that the topological edge\nstates in non-trivial lattices have both dipolar and quadrupolar nature. The\nquadrupolar edge states are not only orthogonal to the dipolar edge states, but\nalso spatially localized at different sublattices. Furthermore, the quadrupolar\ntopological edge states, which coexist at the same energy with the quadrupolar\nflat band have shorter localization length and hence smaller mode volume than\nthe conventional dipolar edge states. The findings deepen our understanding in\ntopological systems that involve higher-order multipoles, or in analogy to the\nwave functions in quantum systems with higher-orbital angular momentum, and may\nbe useful in designing topological systems for confining light robustly and\nenhancing light-matter interactions."
    },
    {
        "anchor": "Negatively Charged Excitons and Photoluminescence in Asymmetric Quantum\n  Well: We study photoluminescence (PL) of charged excitons ($X^-$) in narrow\nasymmetric quantum wells in high magnetic fields B. The binding of all $X^-$\nstates strongly depends on the separation $\\delta$ of electron and hole layers.\nThe most sensitive is the ``bright'' singlet, whose binding energy decreases\nquickly with increasing $\\delta$ even at relatively small B. As a result, the\nvalue of B at which the singlet--triplet crossing occurs in the $X^-$ spectrum\nalso depends on $\\delta$ and decreases from 35 T in a symmetric 10 nm GaAs well\nto 16 T for $\\delta=0.5$ nm. Since the critical values of $\\delta$ at which\ndifferent $X^-$ states unbind are surprisingly small compared to the well\nwidth, the observation of strongly bound $X^-$ states in an experimental PL\nspectrum implies virtually no layer displacement in the sample. This casts\ndoubt on the interpretation of PL spectra of heterojunctions in terms of $X^-$\nrecombination.",
        "positive": "Spin Splitting Induced Photogalvanic Effect in Quantum Wells: A theory of the circular photogalvanic effect caused by spin splitting in\nquantum wells is developed. Direct interband transitions between the hole and\nelectron size-quantized subbands are considered. The photocurrent excitation\nspectrum is shown to depend strongly on the form of the spin-orbit interaction.\nIn the case of structure inversion asymmetry induced (Rashba) spin-splitting,\nthe current is a linear function of light frequency near the absorption edge,\nand for the higher excitation energy the spectrum changes its sign and has a\nminimum. In contrast, when the bulk inversion asymmetry (Dresselhaus splitting)\ndominates, the photocurrent edge behavior is parabolic, and then the spectrum\nis sign-constant and has a maximum."
    },
    {
        "anchor": "Density-functional theory for systems with noncollinear spin:\n  orbital-dependent exchange-correlation functionals and their application to\n  the Hubbard dimer: A new class of orbital-dependent exchange-correlation (xc) potentials for\napplications in noncollinear spin-density-functional theory is developed.\nStarting from the optimized effective potential (OEP) formalism for the exact\nexchange potential - generalized to the noncollinear case - correlation effects\nare added via a self-consistent procedure inspired by the\nSingwi-Tosi-Land-Sjolander (STLS) method. The orbital-dependent xc potentials\nare applied to the Hubbard dimer in uniform and noncollinear magnetic fields\nand compared to exact diagonalization and to the Bethe-ansatz local\nspin-density approximation. The STLS gives the overall best performance for\ntotal energies, densities and magnetizations, particularly in the weakly to\nmoderately correlated regime.",
        "positive": "Nanoscale torsional dissipation dilution for quantum experiments and\n  precision measurement: We show that torsion resonators can experience massive dissipation dilution\ndue to nanoscale strain, and draw a connection to a century-old theory from the\ntorsion balance community which suggests that a simple torsion ribbon is\nnaturally soft-clamped. By disrupting a commonly held belief in the\nnanomechanics community, our findings invite a rethinking of strategies towards\nquantum experiments and precision measurement with nanomechanical resonators.\nFor example, we revisit the optical lever technique for monitoring\ndisplacement, and find that the rotation of a strained nanobeam can be resolved\nwith an imprecision smaller than the zero-point motion of its fundamental\ntorsional mode, without the use of a cavity or interferometric stability. We\nalso find that a strained torsion ribbon can be mass-loaded without changing\nits $Q$ factor. We use this strategy to engineer a chip-scale torsion balance\nwhose resonance frequency is sensitive to micro-$g$ fluctuations of the local\ngravitational field. Enabling both these advances is the fabrication of\nhigh-stress Si$_3$N$_4$ nanobeams with width-to-thickness ratios of $10^4$ and\nthe recognition that their torsional modes have $Q$ factors scaling as their\nwidth-to-thickness ratio squared, yielding $Q$ factors as high as $10^8$ and\n$Q$-frequency products as high as $10^{13}$ Hz."
    },
    {
        "anchor": "Improving the conductance of carbon nanotube networks through resonant\n  momentum exchange: We present a mechanism to improve the conductivity of carbon nanotube (CNT)\nnetworks by improving the conductance between CNTs of different chirality. We\nargue generally that a weak perturbation can greatly improve the inter-tube\nconductance by allowing momentum-conserving tunnelling. The mechanism is\nverified with a tight-binding model, allowing an investigation of its impact\nfor a network containing a range of chiralities. We discuss practical\nimplementations, and conclude that it may be effected by weak physical\ninteractions, and therefore does not require chemical bonding to the CNTs.",
        "positive": "Plasmonic Graded-Chains as Deep-Subwavelength Light Concentrators: We have studied the plasmonic properties of aperiodic arrays of identical\nnanoparticles (NPs) formed by two opposite and equal graded-chains (a chain\nwhere interactions change gradually). We found that these arrays concentrate\nthe external electromagnetic fields even in the long wavelength limit. The\nphenomenon was understood by identifying the system with an effective cavity\nwhere plasmonics excitations are trapped between effective band edges,\nresulting from the change of passband with NP's position. Dependence of\nexcitation concentration on several system's parameter was also assessed. This\nincludes, different gradings as well as NP's couplings, damping, and resonant\nfrequencies. In the spirit of the scaling laws in condensed matter physics, we\ndeveloped a theory that allows us to rationalize all these system's parameters\ninto universal curves. The theory is quite general and can also be used on many\nother situations (different arrays for example). Additionally, we also provided\nan analytical solution, in the tight-binding limit, for the plasmonic response\nof homogeneous linear chains of NPs illuminated by a plane wave. Our results\ncan find applications on sensing, near field imaging, plasmon-enhanced\nphotodetectors, as well as to increase solar cell efficiency."
    },
    {
        "anchor": "Molecular Assembly on Two-Dimensional Materials: Molecular self-assembly is a well-known technique to create highly functional\nnanostructures on surfaces. Self-assembly on two-dimensional materials is a\ndeveloping field and has already resulted in the discovery of several rich and\ninteresting phenomena. Here, we review this progress with an emphasis on the\nelectronic properties of the adsorbates and the substrate in well-defined\nsystems, as unveiled by scanning tunneling microscopy (STM). We cover three\naspects of the self-assembly. The first one focuses on non-covalent\nself-assembly dealing with site-selectivity due to inherent moire pattern\npresent on 2D materials deposited on substrates. Modification of intermolecular\ninteractions and molecule-substrate interactions influences the assembly\ndrastically and 2D materials can also be used as a platform to carry out\ncovalent and metal-coordinated assembly. The second part deals with the\nelectronic properties of molecules adsorbed on 2D materials. By virtue of being\ninert and possessing low density of states near the Fermi level, 2D materials\ndecouple molecules electronically from the underlying metal substrate and allow\nhigh-resolution spectroscopy and imaging of molecular orbitals. The moire\npattern on the 2D materials causes site-selective gating and charging of\nmolecules in some cases. The last section covers the effects of self-assembled\norganic molecules on the electronic properties of graphene as revealed by\nspectroscopy and electrical transport measurements. Non-covalent\nfunctionalization of 2D materials has already been applied for their\napplication as catalysts and sensors. With the current surge of activity on\nbuilding van der Waals heterostructures from 2D materials, molecular\nself-assembly has the potential to add an extra level of flexibility and\nfunctionality for applications ranging from flexible electronics and OLEDs to\nnovel electronic devices and spintronics.",
        "positive": "Evidence of electronic cloaking from chiral electron transport in\n  bilayer graphene nanostructures: The coupling of charge carrier motion and pseudospin via chirality for\nmassless Dirac fermions in monolayer graphene has generated dramatic\nconsequences, such as the unusual quantum Hall effect and Klein tunneling. In\nbilayer graphene, charge carriers are massive Dirac fermions with a finite\ndensity of states at zero energy. Because of their non-relativistic nature,\nmassive Dirac fermions can provide an even better test bed with which to\nclarify the importance of chirality in transport measurement than massless\nDirac fermions in monolayer graphene. Here, we report an electronic cloaking\neffect as a manifestation of chirality by probing phase coherent transport in\nchemical-vapor-deposited bilayer graphene. Conductance oscillations with\ndifferent periodicities were observed on extremely narrow bilayer graphene\nheterojunctions through electrostatic gating. Using a Fourier analysis\ntechnique, we identified the origin of each individual interference pattern.\nImportantly, the electron waves on the two sides of the potential barrier can\nbe coupled through the evanescent waves inside the barrier, making the confined\nstates underneath the barrier invisible to electrons. These findings provide\ndirect evidence for the electronic cloaking effect and hold promise for the\nrealization of pseudospintronics based on bilayer graphene."
    },
    {
        "anchor": "Current induced switching of magnetic domains to a perpendicular\n  configuration: In a ferromagnet--normal-metal--ferromagnet trilayer, a current flowing\nperpendicularly to the layers creates a torque on the magnetic moments of the\nferromagnets. When one of the contacts is superconducting, the torque not only\nfavors parallel or antiparallel alignment of the magnetic moments, as is the\ncase for two normal contacts, but can also favor a configuration where the two\nmoments are perpendicular. In addition, whereas the conductance for parallel\nand antiparallel magnetic moments is the same, signalling the absence of giant\nmagnetoresistance in the usual sense, the conductance is greater in the\nperpendicular configuration. Thus, a negative magnetoconductance is predicted,\nin contrast with the usual giant magnetoresistance.",
        "positive": "Energy relaxation and thermalization of hot electrons in quantum wires: We develop a theory of energy relaxation and thermalization of hot carriers\nin real quantum wires. Our theory is based on a controlled perturbative\napproach for large excitation energies and emphasizes the important roles of\nthe electron spin and finite temperature. Unlike in higher dimensions,\nrelaxation in one-dimensional electron liquids requires three-body collisions\nand is much faster for particles than holes which relax at nonzero temperatures\nonly. Moreover, co-moving carriers thermalize more rapidly than\ncounterpropagating carriers. Our results are quantitatively consistent with a\nrecent experiment."
    },
    {
        "anchor": "Irradiation induced vacancy creation in single walled carbon nanotubes: Single walled carbon nanotubes of 2 nm diameter and 3 to 13 micro meter\nlength were compressed in Cu bullets and irradiated with positive ions of Cs\nwith energies from 0.2 to 2.0 keV and subjected to successively increasing Cs\ndose. From the mass spectra of the sputtered carbon atoms and clusters as a\nfunction of Cs energy the monitoring of trend of the relative number densities\nof the fragmenting species indicates the accumulating damage. Irradiation\ninduced fragmentation provide clues to the structural changes as a result of\ncreation of vacancies due to the sputtering of monatomic, diatomic, triatomic\nand higher species. Monitoring of the the irradiated target electrical\nconductivity provides information of the sequences of the transformation that\nmay be occurring in the structures of the single walled carbon nanotube as a\nfunction of Cs energy and dose.",
        "positive": "Controlling quantum transport through a single molecule: We investigate multi-terminal quantum transport through single monocyclic\naromatic annulene molecules, and their derivatives, using the nonequilibrium\nGreen function approach in the self-consistent Hartree-Fock approximation. A\nnew device concept, the Quantum Interference Effect Transistor (QuIET) is\nproposed, exploiting perfect destructive interference stemming from molecular\nsymmetry, and controlling current flow by introducing decoherence and/or\nelastic scattering that break the symmetry. This approach overcomes the\nfundamental problems of power dissipation and environmental sensitivity that\nbeset many nanoscale device proposals."
    },
    {
        "anchor": "Behavior of implanted Xe, Kr and Ar in nanodiamond and thin graphene\n  stacks: experiment and modeling: Implantation and subsequent behaviour of heavy noble gases (Ar, Kr, Xe) in\nfew-layer graphene sheets and in nanodiamonds is studied both using\ncomputational methods and experimentally using X-ray absorption spectroscopy.\nX-ray absorption spectroscopy provides substantial support for the Xe-vacancy\n(Xe-V) defect as a main site for Xe in nanodiamond. It is shown that noble\ngases in thin graphene stacks distort the layers, forming bulges. The energy of\nan ion placed in between flat graphene sheets is notably lower than in domains\nwith high curvature. However, if the ion is trapped in the curved domain,\nconsiderable additional energy is required to displace it.",
        "positive": "Spin-orbit interaction and snake states in graphene $p$-$n$ junctions: We study a model of a $p$-$n$ junction in single-layer graphene in the\npresence of a perpendicular magnetic field and spin-orbit interactions. By\nsolving the relevant quantum-mechanical problem for a potential step, we\ndetermine the exact spectrum of spin-resolved dispersive Landau levels. Close\nto zero energy, we find a pair of linearly dispersing zero modes, which possess\na wave-vector-dependent spin polarization and can be regarded as quantum\nanalogous of spinful snake states. We show that the Rashba spin-orbit\ninteraction, in particular, produces a wave vector shift between the\ndispersions of these modes with observable interference effects. These effects\ncan in principle provide a way to detect the presence of Rashba spin-orbit\ninteraction and measure its strength. Our results suggest that a graphene\n$p$-$n$ junction in the presence of strong spin-orbit interaction could be used\nas a building block in a spin field-effect transistor."
    },
    {
        "anchor": "Spin polarization oscillations without spin precession: spin-orbit\n  entangled resonances in quasi-one-dimensional spin transport: Resonant behavior involving spin-orbit entangled states occurs for spin\ntransport along a narrow channel defined in a two-dimensional electron gas,\nincluding an apparent rapid relaxation of the spin polarization for special\nvalues of the channel width and applied magnetic field (so-called ballistic\nspin resonance). A fully quantum mechanical theory for transport through\nmultiple subbands of the one-dimensional system provides the dependence of the\nspin transport on the applied magnetic field and channel width, including a\nresonant depolarization of spins when the Zeeman energy matches the subband\nenergy splittings and a spin texture transverse to the magnetic field. The\nresonance phenomenon is robust to disorder.",
        "positive": "Magneto-Transport Properties of Exfoliated Graphene on GaAs: We studied the magneto-transport properties of graphene prepared by\nexfoliation on a III V semiconductor substrate. Tuneability of the carrier\ndensity of graphene was achieved by using a doped GaAs substrate as a\nback-gate. A GaAs/AlAs multilayer, designed to render the exfoliated graphene\nflakes visible, also provides the required back-gate insulation. Good\ntuneability of the graphene carrier density is obtained, and the typical Dirac\nresistance characteristic is observed despite the limited height of the\nmultilayer barrier compared to the usual SiO2 oxide barrier on doped silicon.\nIn a magnetic field weak localization effects as well as the quantum Hall\neffect of a graphene monolayer are studied."
    },
    {
        "anchor": "Topological Anderson amorphous insulator: The topological phase in amorphous systems adds a new dimension to the\ntopological states of matter. Here, we present an interesting phenomenon dubbed\nthe topological Anderson amorphous insulator (TAAI). Anderson disorder can\ndrive topologically trivial amorphous systems with structural disorders into\nnoncrystalline topological insulators. The gap closing and reopening, spin Bott\nindex, robust edge states, and quantized conductance characterize the Anderson\ndisorder-induced nontrivial topology in amorphous systems. More importantly,\nphase diagrams are given for the topological phase transition (TPT). It is\nfound that amorphous structural disorder and Anderson disorder are synergistic\nto drive the s-p band inversion of the system and hence the TPT, which is\nfurther confirmed by the effective medium theory. Our findings report a\ndisorder-induced topological phenomenon in noncrystalline systems and shed\nlight on the physical understanding of the interplay between the coexistence of\ntwo types of disorder effects and topology.",
        "positive": "Enhanced quantum oscillatory magnetization and non-equilibrium currents\n  in an interacting two-dimensional electron system in MgZnO/ZnO with repulsive\n  scatterers: Torque magnetometry at low temperature and in high magnetic fields B is\nperformed on a MgZnO/ZnO heterostructure incorporating a high-mobility\ntwo-dimensional electron system. We find a sawtooth-like quantum oscillatory\nmagnetization M(B), i.e., the de Haas-van Alphen (dHvA) effect. At the same\ntime, unexpected spike-like overshoots in M and non-equilibrium currents are\nobserved which allow us to identify the microscopic nature and density of the\nresidual disorder. The acceptor-like scatterers give rise to a magnetic thaw\ndown effect which enhances the dHvA amplitude beyond the electron-electron\ninteraction effects being present in the MgZnO/ZnO heterostructure"
    },
    {
        "anchor": "Double-Free-Layer Stochastic Magnetic Tunnel Junctions with Synthetic\n  Antiferromagnets: Stochastic magnetic tunnel junctions (sMTJ) using low-barrier nanomagnets\nhave shown promise as fast, energy-efficient, and scalable building blocks for\nprobabilistic computing. Despite recent experimental and theoretical progress,\nsMTJs exhibiting the ideal characteristics necessary for probabilistic bits\n(p-bit) are still lacking. Ideally, the sMTJs should have (a) voltage bias\nindependence preventing read disturbance (b) uniform randomness in the\nmagnetization angle between the free layers, and (c) fast fluctuations without\nrequiring external magnetic fields while being robust to magnetic field\nperturbations. Here, we propose a new design satisfying all of these\nrequirements, using double-free-layer sMTJs with synthetic antiferromagnets\n(SAF). We evaluate the proposed sMTJ design with experimentally benchmarked\nspin-circuit models accounting for transport physics, coupled with the\nstochastic Landau-Lifshitz-Gilbert equation for magnetization dynamics. We find\nthat the use of low-barrier SAF layers reduces dipolar coupling, achieving\nuncorrelated fluctuations at zero-magnetic field surviving up to diameters\nexceeding ($D\\approx 100$ nm) if the nanomagnets can be made thin enough\n($\\approx 1$-$2$ nm). The double-free-layer structure retains bias-independence\nand the circular nature of the nanomagnets provides near-uniform randomness\nwith fast fluctuations. Combining our full sMTJ model with advanced transistor\nmodels, we estimate the energy to generate a random bit as $\\approx$ 3.6 fJ,\nwith fluctuation rates of $\\approx$ 3.3 GHz per p-bit. Our results will guide\nthe experimental development of superior stochastic magnetic tunnel junctions\nfor large-scale and energy-efficient probabilistic computation for problems\nrelevant to machine learning and artificial intelligence.",
        "positive": "Radiatively limited dephasing and exciton dynamics in MoSe$_2$\n  monolayers: By implementing four-wave mixing (FWM) micro-spectroscopy we measure\ncoherence and population dynamics of the exciton transitions in monolayers of\nMoSe$_2$. We reveal their dephasing times T$_2$ and radiative lifetime T$_1$ in\na sub-picosecond (ps) range, approaching T$_2$=2T$_1$, and thus indicating\nradiatively limited dephasing at a temperature of 6$\\,$K. We elucidate the\ndephasing mechanisms by varying the temperature and by probing various\nlocations on the flake exhibiting a different local disorder. At a nanosecond\nrange, we observe the residual FWM produced by the incoherent excitons, which\ninitially disperse towards the dark states, but then relax back to the\noptically active states within the light cone. By introducing\npolarization-resolved excitation, we infer inter-valley exciton dynamics,\nshowing an initial polarization degree of around 30$\\,\\%$, constant during the\ninitial sub-picosecond decay, followed by the depolarization on a picosecond\ntimescale. The FWM hyperspectral imaging reveals the doped and undoped areas of\nthe sample, allowing to investigate the neutral exciton, the charged one or\nboth transitions at the same time. In the latter case, we observe the\nexciton-trion beating in the coherence evolution indicating their coherent\ncoupling."
    },
    {
        "anchor": "Electronic spin transport and spin precession in single graphene layers\n  at room temperature: The specific band structure of graphene, with its unique valley structure and\nDirac neutrality point separating hole states from electron states has led to\nthe observation of new electronic transport phenomena such as anomalously\nquantized Hall effects, absence of weak localization and the existence of a\nminimum conductivity. In addition to dissipative transport also supercurrent\ntransport has already been observed. It has also been suggested that graphene\nmight be a promising material for spintronics and related applications, such as\nthe realization of spin qubits, due to the low intrinsic spin orbit\ninteraction, as well as the low hyperfine interaction of the electron spins\nwith the carbon nuclei. As a first step in the direction of graphene\nspintronics and spin qubits we report the observation of spin transport, as\nwell as Larmor spin precession over micrometer long distances using single\ngraphene layer based field effect transistors. The non-local spin valve\ngeometry was used, employing four terminal contact geometries with\nferromagnetic cobalt electrodes, which make contact to the graphene sheet\nthrough a thin oxide layer. We observe clear bipolar (changing from positive to\nnegative sign) spin signals which reflect the magnetization direction of all 4\nelectrodes, indicating that spin coherence extends underneath all 4 contacts.\nNo significant changes in the spin signals occur between 4.2K, 77K and room\ntemperature. From Hanle type spin precession measurements we extract a spin\nrelaxation length between 1.5 and 2 micron at room temperature, only weakly\ndependent on charge density, which is varied from n~0 at the Dirac neutrality\npoint to n = 3.6 10^16/m^2. The spin polarization of the ferromagnetic contacts\nis calculated from the measurements to be around 10%.",
        "positive": "Kronig-Penney model on bilayer graphene: spectrum and transmission\n  periodic in the strength of the barriers: We show that the transmission through single and double {\\delta}-function\npotential barriers of strength P in bilayer graphene is periodic in P with\nperiod {\\pi}. For a certain range of P values we find states that are bound to\nthe potential barrier and that run along the potential barrier. Similar\nperiodic behaviour is found for the conductance. The spectrum of a periodic\nsuccession of {\\delta}-function barriers (Kronig-Penney model) in bilayer\ngraphene is periodic in P with period 2{\\pi}. For P smaller than a critical\nvalue, the spectrum exhibits two Dirac points while for P larger than this\nvalue an energy gap opens. These results are extended to the case of a\nsuperlattice of {\\delta}-function barriers with P alternating in sign between\nsuccessive barriers; the corresponding spectrum is periodic in P with period\n{\\pi}."
    },
    {
        "anchor": "Square-root Floquet topological phases and time crystals: Periodically driven (Floquet) phases are attractive due to their ability to\nhost unique physical phenomena with no static counterparts. We propose a\ngeneral approach in nontrivially devising a square-root version of existing\nFloquet phases, applicable both in noninteracting and interacting setting. The\nresulting systems are found to yield richer physics that is otherwise absent in\nthe original counterparts and is robust against parameter imperfection. These\ninclude the emergence of Floquet topological superconductors with arbitrarily\nmany zero, $\\pi$, and $\\pi/2$ edge modes, as well as $4T$-period Floquet time\ncrystals in disordered and disorder-free systems ($T$ being the driving\nperiod). Remarkably, our approach can be repeated indefinitely to obtain a\n2nth-root version of a given system, thus allowing for the discovery and\nsystematic construction of a family of exotic Floquet phases.",
        "positive": "Four band tunneling in bilayer graphene: The conductance, the transmission and the reflection probabilities through\nrectangular potential barriers and pn-junctions are obtained for bilayer\ngraphene taking into account the four bands of the energy spectrum. We have\nevaluated the importance of the skew hopping parameters {\\gamma}3 and {\\gamma}4\nto these properties and show that for energies E>{\\gamma}1/100 their effect is\nnegligible. For high energies two modes of propagation exist and we investigate\nscattering between these modes. For perpendicular incidence both propagation\nmodes are decoupled and scattering between them is forbidden. This extends the\nconcept of pseudospin as defined within the two band approximation to a four\nband model and corresponds to the (anti)symmetry of the wavefunctions under\nin-plane mirroring. New transmission resonances are found that appear as sharp\npeaks in the conductance which are absent in the two band approximation. The\napplication of an interlayer bias to the system: 1) breaks the pseudospin\nstructure, 2) opens a bandgap that results in a distinct feature of suppressed\ntransmission in the conductance, and 3) breaks the angular symmetry with\nrespect to normal incidence in the transmission and reflection."
    },
    {
        "anchor": "Fano and Dicke effects and spin polarization in a double Rashba-ring\n  system side coupled to a quantum wire: The electronic transport in a system of two quantum rings side-coupled to a\nquantum wire is studied via a single-band tunneling tight-binding Hamiltonian.\nWe derived analytical expressions for the conductance and spin polarization\nwhen the rings are threaded by magnetic fluxes with Rashba spin-orbit\ninteraction. We show that by using the Fano and Dicke effects this system can\nbe used as an efficient spin-filter even for small spin orbit interaction and\nsmall values of magnetic flux. We compare the spin-dependent polarization of\nthis design and the polarization obtained with one ring side coupled to a\nquantum ring. As a main result, we find better spin polarization capabilities\nas compared to the one ring design",
        "positive": "Qualitative Insight and Quantitative Analysis of the Effect of\n  Temperature on the Coercivity of a Magnetic System: The temperature dependence of the response of a magnetic system to an applied\nfield can be understood qualitatively by considering variations in the energy\nsurface characterizing the system and estimated quantitatively with rate\ntheory. In the system analysed here, Fe/Sm-Co spring magnet, the width of the\nhysteresis loop is reduced to a half when temperature is raised from 25~K to\n300~K. This narrowing can be explained and reproduced quantitatively without\ninvoking temperature dependence of model parameters as has typically been done\nin previous data analysis. The applied magnetic field lowers the energy barrier\nfor reorientation of the magnetization but thermal activation brings the system\nover the barrier. A 2-dimensional representation of the energy surface is\ndeveloped and used to gain insight into the transition mechanism and to\ndemonstrate how the applied field alters the transition path. Our results show\nthe importance of explicitly including the effect of thermal activation when\ninterpreting experiments involving the manipulation of magnetic systems at\nfinite temperature."
    },
    {
        "anchor": "Gate control of superconductivity in mesoscopic all-metallic devices: It was recently demonstrated the possibility to tune, through the application\nof a control gate voltage, the superconducting properties of mesoscopic devices\nbased on Bardeen-Cooper-Schrieffer metals. In spite of the several experimental\nevidence obtained on different materials and geometries, a description of the\nmicroscopic mechanism at the basis of such unconventional effect has not been\nprovided yet. This work discusses the technological potential of gate control\nof superconductivity in metallic superconductors and revises the experimental\nresults which provide information regarding a possible thermal origin of the\neffect: in the first place, we review experiments performed on high critical\ntemperature elemental superconductors (niobium and vanadium) and show how\ndevices based on these materials can be exploited to realize basic electronic\ntools such as, e. g., a half-wave rectifier. In a second part, we discuss the\norigin of the gating effect by showing the gate-driven suppression of the\nsupercurrent in a suspended titanium wire and by providing a comparison between\nthermal and electric switching current probability distributions. Furthermore,\nwe discuss the cold field-emission of electrons from the gate by means of\nfinite element simulations and compare the results with experimental data.\nFinally, the presented data provide a strong indication regarding the\nunlikelihood of thermal origin of the gating effect.",
        "positive": "Voltage-tunable singlet-triplet transition in lateral quantum dots: Results of calculations and high source-drain transport measurements are\npresented which demonstrate voltage-tunable entanglement of electron pairs in\nlateral quantum dots. At a fixed magnetic field, the application of a\njudiciously-chosen gate voltage alters the ground-state of an electron pair\nfrom an entagled spin singlet to a spin triplet."
    },
    {
        "anchor": "Photonic graph state generation from quantum dots and color centers for\n  quantum communications: Highly entangled graph states of photons have applications in universal\nquantum computing and in quantum communications. In the latter context, they\nhave been proposed as the key ingredient in the establishment of long-distance\nentanglement across quantum repeater networks. Recently, a general\ndeterministic approach to generate repeater graph states from quantum emitters\nwas given. However, a detailed protocol for the generation of such states from\nrealistic systems is still needed in order to guide experiments. Here, we\nprovide such explicit protocols for the generation of repeater graph states\nfrom two types of quantum emitters: NV centers in diamond and self-assembled\nquantum dots. A crucial element of our designs is an efficient controlled-Z\ngate between the emitter and a nuclear spin, used as an ancilla qubit.\nAdditionally, a fast protocol for using pairs of exchange-coupled quantum dots\nto produce repeater graph states is described. Our focus is on near-term\nexperiments feasible with existing experimental capabilities.",
        "positive": "Spin backflow: a non-Markovian effect on spin pumping: The miniaturization of spintronic devices, specifically, nanoscale devices\nemploying spintronics, has attracted intensive attention from a scientific as\nwell as engineering perspective. In this paper, we study non-Markovian effect\non spin pumping to describe spin current generation driven by arbitrary\nprecession frequency of magnetization in a quantum dot attached to an electron\nlead. Although the Markovian approximation can be used when driving is\nsufficiently slow compared with relaxation times in electron tunneling, recent\ndevelopments in nano-spintronic devices show that we need to include\nnon-Markovian effects. In contrast to the one-way-only nature of the spin\ncurrent generation under the Markovian dynamics, we find that the non-Markovian\ndynamics exhibits a temporal backflow of spin, call spin backflow for brevity.\nWe capture the phenomenon by introducing its quantifier, and show that the\nbackflow significantly reduces the amount of spin current when the frequency\nexceeds the relaxation rate. This prevents unphysical divergence of the spin\ncurrent in the high frequency limit that occurs under the Markovian\napproximation. We believe our analysis provides an understanding of the spin\npumping particularly in regard to producing a more efficient spin current\ngeneration over shorter time scales by going beyond the conventional Markovian\napproximation."
    },
    {
        "anchor": "Statistical properties of electrochemical capacitance in disordered\n  mesoscopic capacitors: We numerically investigate the statistical properties of electrochemical\ncapacitance in disordered two-dimensional mesoscopic capacitors. Based on the\ntight-binding Hamiltonian, the Green's function formalism is adopted to study\nthe average electrochemical capacitance, its fluctuation as well as the\ndistribution of capacitance of the disordered mesoscopic capacitors for three\ndifferent ensembles: orthogonal (symmetry index \\beta=1), unitary (\\beta=2),\nand symplectic (\\beta=4). It is found that the electrochemical capacitance in\nthe disordered systems exhibits universal behavior. In the case of single\nconducting channel, the electrochemical capacitance follows a symmetric\nGaussian distribution at weak disorders as expected from the random matrix\ntheory. In the strongly disordered regime, the distribution is found to be a\nsharply one-sided form with a nearly-constant tail in the large capacitance\nregion. This behavior is due to the existence of the necklace states in\ndisordered systems, which is characterized by the multi-resonance that gives\nrise to a large density of states. In addition, it is found that the necklace\nstate also enhances the fluctuation of electrochemical capacitance in the case\nof single conducting channel. When the number of conducting channels increases,\nthe influence of necklace states becomes less important. For large number of\nconducting channels, the electrochemical capacitance fluctuation develops a\nplateau region in the strongly disordered regime. The plateau value is\nidentified as universal electrochemical capacitance fluctuation, which is\nindependent of system parameters such as disorder strength, Fermi energy,\ngeometric capacitance, and system size. Importantly, the universal\nelectrochemical capacitance fluctuation is the same for all three ensembles,\nsuggesting a super-universal behavior.",
        "positive": "Ultrafast current and field driven domain-wall dynamics in van der Waals\n  antiferromagnet MnPS3: The discovery of magnetism in two-dimensional (2D) van der Waals (vdW)\nmaterials has flourished a new endeavour of fundamental problems in magnetism\nas well as potential applications in computing, sensing and storage\ntechnologies. Of particular interest are antiferromagnets, which due to their\nintrinsic antiferromagnetic exchange coupling show several advantages in\nrelation to ferromagnets such as robustness against external magnetic\nperturbations. This property is one of the cornerstones of antiferromagnets and\nimplies that information stored in antiferromagnetic domains is invisible to\napplied magnetic fields preventing it from being erased or manipulated. Here we\nshow that, despite this fundamental understanding, the magnetic domains of\nrecently discovered vdW MnPS3 antiferromagnet can be controlled via external\nmagnetic fields and currents. We realize ultrafast domain-wall dynamics with\nvelocities up to 1500 m/s and 3000 m/s respectively to a broad range of fields\nand current densities. Both domain wall dynamics are determined by the edge\nterminations which generated uncompensated spins following the underlying\nsymmetry of the honeycomb structure. We find that edge atoms belonging to\ndifferent magnetic sublattices function as geometrical constrictions preventing\nthe displacement of the wall, whereas having atoms of the same sublattice at\nboth edges of the material allows for the field-driven domain wall motion which\nis only limited by the spin-flop transition of the antiferromagnet beyond 25 T.\nConversely, electric currents can induce motion of domain walls in most of the\nedges except those where the two sublattices are present at the borders (e.g.\narmchair edges). Our results indicate that the implementation of 2D vdW\nantiferromagnets in real applications requires the engineering of the layer\nedges which enables an unprecedented functional feature in ultrathin device\nplatforms."
    },
    {
        "anchor": "Electric field-induced valley degeneracy lifting in uniaxial strained\n  graphene: evidence from magnetophonon resonance: A double peak structure in the magneto-phonon resonance (MPR) spectrum of\nuniaxial strained graphene, under crossed electric and magnetic fields, is\npredicted. We focus on the $\\Gamma$ point optical phonon modes coupled to the\ninter-Landau level transitions $0 \\leftrightarrows \\pm 1$ where MPR is expected\nto be more pronounced at high magnetic field. We derive the frequency shifts\nand the broadenings of the longitudinal (LO) and transverse (TO) optical phonon\nmodes taking into account the effect of the strain modified electronic spectrum\non the electron-phonon coupling. We show that the MPR lines acquire a double\nresonance structure originating from the two-fold valley degeneracy lifting.\nThe latter is due to the different Landau level spacings in the two Dirac\nvalleys resulting form the simultaneous action of the inplane electric field\nand the strain induced Dirac cone tilt. We discuss the role of some key\nparameters such as disorder, strain, doping and electric field amplitude on the\nemergence of the double resonance structure.",
        "positive": "Pair Partitioning in time reversal acoustics: Time reversal of acoustic waves can be achieved efficiently by the persistent\ncontrol of excitations in a finite region of the system. The procedure, called\nTime Reversal Mirror, is stable against the inhomogeneities of the medium and\nit has numerous applications in medical physics, oceanography and\ncommunications. As a first step in the study of this robustness, we apply the\nPerfect Inverse Filter procedure that accounts for the memory effects of the\nsystem. In the numerical evaluation of such procedures we developed the Pair\nPartitioning method for a system of coupled oscillators. The algorithm,\ninspired in the Trotter strategy for quantum dynamics, obtains the dynamic for\na chain of coupled harmonic oscillators by the separation of the system in\npairs and applying a stroboscopic sequence that alternates the evolution of\neach pair. We analyze here the formal basis of the method and discuss his\nextension for including energy dissipation inside the medium."
    },
    {
        "anchor": "Quantum Dots with Disorder and Interactions: A Solvable Large-g Limit: We show that problem of interacting electrons in a quantum dot with chaotic\nboundary conditions is solvable in the large-g limit, where g is the\ndimensionless conductance of the dot. The critical point of the $g=\\infty$\ntheory (whose location and exponent are known exactly) that separates strong\nand weak-coupling phases also controls a wider fan-shaped region in the\ncoupling-1/g plane, just as a quantum critical point controls the fan in at\nT>0. The weak-coupling phase is governed by the Universal Hamiltonian and the\nstrong-coupling phase is a disordered version of the Pomeranchuk transition in\na clean Fermi liquid. Predictions are made in the various regimes for the\nCoulomb Blockade peak spacing distributions and Fock-space delocalization\n(reflected in the quasiparticle width and ground state wavefunction).",
        "positive": "Pairing Symmetry, Phase diagram and Edge Modes in Topological\n  Fulde-Ferrell-Larkin-Ovchinnikov Phase: The realizations of spin-orbit coupling in cold atoms lead to a burst of\nresearch activities in the searching of topological matters in ultracold atom\nsystems. The very recent theoretical predictions show that topological\nFulde-Ferrell-Larkin-Ovchinnikov (FFLO) superfluids can be realized with proper\nspin-orbit coupling and Zeeman fields. In this work, a comprehensive\nunderstanding of the pairing symmetry, phase diagram and the edge modes in this\nnew topological matter are presented. The momentum of the Cooper pairs plays\nthe role of renormalizing the in-plane Zeeman field and chemical potential. The\nin-plane Zeeman field and finite momentum pairing induce asymmetry to the\neffective $p$-wave pairing, apart from a small fraction of higher orbital\ncomponents. The phase diagram is composed by different phases, which are\ndetermined by the topology and band gap nature of the superfluids. Especially,\nthe gapped and gapless topological FFLO phase have totally different finite\nsize effect. These novel features show that the spin-orbit coupled cold atoms\nprovides an important platform in realizing topological matters which may not\nbe materialized with solids."
    },
    {
        "anchor": "Quantum Hall Effect in a Rotating Bose-Einstein Condensate: An Atomic\n  Twin of the Electronic Brother?: We exploit the analogy with the quantum Hall (QH) effect for electrons to\nstudy the possible atomic QH states of a rapidly-rotating Bose-Einstein\ncondensate. Actually, there is a nearly perfect map of the present problem in\nthe QH regime to the QH physics for electrons. The profound map enables one to\ngive a physically appealing definitions of the filling fraction and the \"atomic\nHall conductance\" that is quantized for atomic Laughlin states. This\nquantization might imply an exotic fractionalization of atomic mass. We also\nbriefly discuss an effective Chern-Simons theory for describing the atomic QH\nliquids where a gravitational-like field naturally emerges.",
        "positive": "Energy Levels of Gapped Graphene Quantum Dot in Magnetic Field: We study the energy levels of carriers confined in a magnetic quantum dot of\ngraphene surrounded by a infinite graphene sheet in the presence of energy gap.\nThe eigenspinors are derived for the valleys $K$ and $K'$, while the associated\nenergy levels are obtained by using the boundary condition at interface of the\nquantum dot. We numerically investigate our results and show that the energy\nlevels exhibit the symmetric and antisymmetric behaviors under suitable\nconditions of the physical parameters. We find that the radial probability can\nbe symmetric or antisymmeric according to the angular momentum is null or\nno-null. Finally, we show that the application of an energy gap decreases the\nelectron density in the quantum dot, which indicates a temporary trapping of\nelectrons."
    },
    {
        "anchor": "DMPK Equation for Transmission Eigenvalues in Metallic Carbon Nanotubes: The Dorokhov-Mello-Pereyra-Kumar (DMPK) equation for transmission eigenvalues\nis derived for metallic carbon nanotubes with several conducting channels when\nthe potential range of scatterers is larger than the lattice constant. With\nincreasing system length L, the system approaches a fixed point, where only one\nchannel is perfectly conducting and other channels are completely closed. The\nasymptotic behavior of the conductance in the long-L regime is investigated on\nthe basis of the DMPK equation. It is shown that the length scale for the\nexponential decay of the typical conductance is reduced due to the presence of\nthe perfectly conducting channel. If a magnetic field is applied, the system\nfalls into the unitary class. It is pointed out that this transition is\ncharacterized by the disappearance of the perfectly conducting channel and the\nincrease in decay length for the typical conductance.",
        "positive": "Analytical approach to semiconductor Bloch equations: Although semiconductor Bloch equations have been widely used for decades to\naddress ultrafast optical phenomena in semiconductors, they have a few\nimportant drawbacks: (i) Coulomb terms between free electron-hole pairs require\nHartree-Fock treatment which, in its usual form, preserves excitonic poles but\nloses biexcitonic resonances. (ii) Solving the resulting coupled differential\nequations imposes heavy numerics which completely hide the physics. This can be\ncompletely avoided if, instead of free electron-hole pairs, we use correlated\npairs, i.e., excitons. Their interactions are easy to handle through the\nrecently constructed composite-exciton many-body theory, which allows us to\n\\emph{analytically} obtain the time evolution of the polarization induced by a\nlaser pulse. This polarization comes from Coulomb interactions between virtual\nexcitons, but also from Coulomb-free fermion exchanges, which are dominant at\nlarge detuning."
    },
    {
        "anchor": "Locking electron spins into magnetic resonance by electron-nuclear\n  feedback: The main obstacle to coherent control of two-level quantum systems is their\ncoupling to an uncontrolled environment. For electron spins in III-V quantum\ndots, the random environment is mostly given by the nuclear spins in the\nquantum dot host material; they collectively act on the electron spin through\nthe hyperfine interaction, much like a random magnetic field. Here we show that\nthe same hyperfine interaction can be harnessed such that partial control of\nthe normally uncontrolled environment becomes possible. In particular, we\nobserve that the electron spin resonance frequency remains locked to the\nfrequency of an applied microwave magnetic field, even when the external\nmagnetic field or the excitation frequency are changed. The nuclear field\nthereby adjusts itself such that the electron spin resonance condition remains\nsatisfied. General theoretical arguments indicate that this spin resonance\nlocking is accompanied by a significant reduction of the randomness in the\nnuclear field.",
        "positive": "Tunable polarization in beam-splitter based on 2D topological insulators: The typical bulk model describing 2D topological insulators (TI) consists of\ntwo types of spin-orbit terms, the so-called Dirac term which induces out-of\nplane spin polarization and the Rashba term which induces in-plane spin\npolarization. We show that for some parameters of the Fermi energy, the beam\nsplitter device built on 2D TIs can achieve higher in-plane spin polarization\nthan one built on materials described by the Rashba model itself. Further, due\nto high tunability of the electron density and the asymmetry of the quantum\nwell, spin polarization in different directions can be obtained. While in the\nnormal (topologically trivial) regime the in-plane spin polarization would\ndominate, in the inverted regime the out-of-plane polarization is more\nsignificant not only in the band gap but also for small Fermi energies above\nthe gap. Further, we suggest a double beam splitter scheme, to measure in-plane\nspin current all electrically. Although we consider here as an example\nHgTe/CdTe quantum wells, this scheme could be also promising for InAs/GaSb QWs\nwhere the in- and out-of-plane polarization could be achieved in a single\ndevice."
    },
    {
        "anchor": "Operating semiconductor quantum processors with hopping spins: Qubits that can be efficiently controlled are pivotal in the development of\nscalable quantum hardware. Resonant control is commonly embraced to execute\nhigh-fidelity quantum gates but demands integration of high-frequency\noscillating signals and results in qubit crosstalk and heating. Establishing\nquantum control based on discrete signals could therefore result in a paradigm\nshift. This may be accomplished with single-spin semiconductor qubits, if one\ncan engineer hopping spins between quantum dots with site-dependent spin\nquantization axis. Here, we introduce hopping-based universal quantum logic and\nobtain single-qubit gate fidelities of 99.97%, coherent shuttling fidelities of\n99.992%, and two-qubit gates fidelities of 99.3%, corresponding to error rates\nthat have been predicted to allow for quantum error correction. We demonstrate\nthat hopping spins also constitute an elegant tuning method by statistically\nmapping the coherence of a 10-quantum dot system. These results motivate dense\nquantum dot arrays with sparse occupation for efficient and high-connectivity\nqubit registers.",
        "positive": "Pseudo-magnetic field-induced ultra-slow carrier dynamics in\n  periodically strained graphene: The creation of pseudo-magnetic fields in strained graphene has emerged as a\npromising route to allow observing intriguing physical phenomena that would be\nunattainable with laboratory superconducting magnets. Scanning tunneling\nspectroscopy experiments have successfully measured the pseudo-Landau levels\nand proved the existence of pseudo-magnetic fields in various strained graphene\nsystems. These giant pseudo-magnetic fields observed in highly deformed\ngraphene can substantially alter the optical properties of graphene beyond a\nlevel that can be feasible with an external magnetic field, but the\nexperimental signatures of the influence of such pseudo-magnetic fields have\nyet to be unveiled. Here, using time-resolved infrared pump-probe spectroscopy,\nwe provide unambiguous evidence for ultra-slow carrier dynamics enabled by\npseudo-magnetic fields in periodically strained graphene. Strong\npseudo-magnetic fields of ~100 T created by non-uniform strain in graphene\nnanopillars are found to significantly decelerate the relaxation processes of\nhot carriers by more than an order of magnitude. Our finding presents\nunforeseen opportunities for harnessing the new physics of graphene enabled by\npseudo-magnetic fields for optoelectronics and condensed matter physics."
    },
    {
        "anchor": "Bifurcation of the Edge-State Width in the Two-Dimensional Topological\n  Insulator: We examine the properties of edge states in a two-dimensional topological\ninsulator. Based on the Kane-Mele model, we derive two coupled equations for\nthe energy and the effective width of edge states at a given momentum in a\nsemi-infinite honeycomb lattice with a zigzag boundary. It is revealed that, in\na one-dimensional Brillouin zone, the edge states merge into the continuous\nbands of the bulk states through a bifurcation of the edge-state width. We\ndiscuss the implications of the results to the experiments in monolayer or thin\nfilms of topological insulators.",
        "positive": "Magnetoresistance in nanostructures: the role of nonuniform current: We developed a method to calculate the magnetoresistance of magnetic\nnanostructures. We discretize a magnetic disk in small cells and numerically\nsolve the Landau-Lifshitz-Gilbert (LLG) equation in order to obtain its\nmagnetization profile. We consider a anisotropic magnetoresistance (AMR) that\ndepends on the local magnetization as the main source of the magnetoresistance.\nWe then use it as an input to calculate the resistance and current distribution\nnumerically, using a relaxation method. We show how magnetoresistance\nmeasurements can be useful to obtain information on the magnetic structure.\nAdditionally, we obtain non-homogeneous current distributions for different\nmagnetic configurations in static and dynamical regimes."
    },
    {
        "anchor": "Short-range interactions in a two-electron system: energy levels and\n  magnetic properties: The problem of two electrons in a square billiard interacting via a\nfinite-range repulsive Yukawa potential and subjected to a constant magnetic\nfield is considered. We compute the energy spectrum for both singlet and\ntriplet states, and for all symmetry classes, as a function of the strength and\nrange of the interaction and of the magnetic field. We show that the\nshort-range nature of the potential suppresses the formation of ``Wigner\nmolecule'' states for the ground state, even in the strong interaction limit.\nThe magnetic susceptibility $\\chi(B)$ shows low-temperature paramagnetic peaks\ndue to exchange induced singlet-triplet oscillations. The position, number and\nintensity of these peaks depend on the range and strength of the interaction.\nThe contribution of the interaction to the susceptibility displays paramagnetic\nand diamagnetic phases as a function of $T$.",
        "positive": "Substrate induced magnetic anisotropies and magneto-optical response in\n  YIG nanosized epitaxial films on NdGG(111): Nanosized Y3Fe5O12 epitaxial films have been grown on Nd3Ga5O12 substrates\nusing laser molecular beam epitaxy method. Magneto-optical polar Kerr effect,\nferromagnetic resonance and spin wave propagation measurements show that the\nstress-related anisotropy field has an opposite sign, compared to that in the\nYIG/GGG systems. This leads to a considerable decrease of the effective\nmagnetization that opens a perspective to get YIG films with perpendicular\nmagnetization for utilizing forward volume spin waves. Longitudinal\nmagnetooptical Kerr effect magnetometry reveals a large contribution of\nquadratic in magnetization terms into dielectric permittivity tensor at optical\nfrequencies. This effect strongly increases with temperature decrease and is\nexplained by magnetization of the interface Nd3+ ions that are exchange coupled\nto the Fe3+ ions."
    },
    {
        "anchor": "Random strain fluctuations as dominant disorder source for high-quality\n  on-substrate graphene devices: We have performed systematic investigations of transport through graphene on\nhexagonal boron nitride (hBN) substrates, together with confocal Raman\nmeasurements and a targeted theoretical analysis, to identify the dominant\nsource of disorder in this system. Low-temperature transport measurements on\nmany devices reveal a clear correlation between the carrier mobility $\\mu$ and\nthe width $n^*$ of the resistance peak around charge neutrality, demonstrating\nthat charge scattering and density inhomogeneities originate from the same\nmicroscopic mechanism. The study of weak-localization unambiguously shows that\nthis mechanism is associated to a long-ranged disorder potential, and provides\nclear indications that random pseudo-magnetic fields due to strain are the\ndominant scattering source. Spatially resolved Raman spectroscopy measurements\nconfirm the role of local strain fluctuations, since the line-width of the\nRaman 2D-peak --containing information of local strain fluctuations present in\ngraphene-- correlates with the value of maximum observed mobility. The\nimportance of strain is corroborated by a theoretical analysis of the relation\nbetween $\\mu$ and $n^*$ that shows how local strain fluctuations reproduce the\nexperimental data at a quantitative level, with $n^*$ being determined by the\nscalar deformation potential and $\\mu$ by the random pseudo-magnetic field\n(consistently with the conclusion drawn from the analysis of\nweak-localization). Throughout our study, we compare the behavior of devices on\nhBN substrates to that of devices on SiO$_2$ and SrTiO$_3$, and find that all\nconclusions drawn for the case of hBN are compatible with the observations made\non these other materials. These observations suggest that random strain\nfluctuations are the dominant source of disorder for high-quality graphene on\nmany different substrates, and not only on hexagonal boron nitride.",
        "positive": "Ground state energy of an interacting electron system in the background\n  of two opposite magnetic strings: Motivated by our earlier work, we show in this paper rigorously that the\nground state energy and degeneracy of an infinitely extended system of\ninteracting electrons in the background of a homogeneous magnetic field and two\nseparated magnetic strings of opposite strength is the same as for the system\nwithout strings. By using symmetry considerations we obtain further that the\nenergy spectrum does not depend on the string separation distance for strictly\npositive distances. As a side effect of our considerations, we obtain a virial\ntheorem for the two string system in the case of a homogeneous interaction\npotential which has the same form as the virial theorem without the strings."
    },
    {
        "anchor": "Double quantum dot coupled to a quantum point contact: A stochastic\n  thermodynamics approach: We study the nonequilibrium properties of an electronic circuit composed of a\ndouble quantum dot (DQD) channel coupled to a quantum point contact (QPC)\nwithin the framework of stochastic thermodynamics. We show that the transition\nrates describing the dynamics satisfy a nontrivial local detailed balance (LDB)\nand that the statistics of energy and particle currents across both channels\nobeys a fluctuation theorem (FT). We analyze two regimes where the device\noperates as a thermodynamic machine and study its output power and efficiency\nfluctuations. We show that the electrons tunneling through the QPC without\ninteracting with the DQD have a strong effect on the device efficiency.",
        "positive": "d+id'-wave Superconducting States in Graphene: We show that effective superconducting orders generally emerge at low energy\nin the superconducting state of graphene with conventionally defined pairing\nsymmetry .\n  We study such a particular interesting example, the $d_{x^2-y^2}+id'_{xy}$\nspin singlet pairing superconducting state in graphene, which can be generated\nby electronic correlation as well as induced through a proximity effect with a\nd-wave superconductor. We find that effectively the d-wave state is a state\nwith mixed s-wave and exotic $p+ip$-wave pairing orders at low energy. This\nremarkable property leads to distinctive superconducting gap functions and\nnovel behavior of the Andreev conductance spectra."
    },
    {
        "anchor": "Exciton-polaron complexes in pulsed electrically-detected magnetic\n  resonance: Several microscopic pathways have been proposed to explain the large magnetic\neffects observed in organic semiconductors, but identifying and characterising\nwhich microscopic process actually influences the overall magnetic field\nresponse is challenging. Pulsed electrically-detected magnetic resonance\nprovides an ideal platform for this task as it intrinsically monitors the\ncharge carriers of interest and provides dynamical information which is\ninaccessible through conventional magnetoconductance measurements. Here we\ndevelop a general time domain theory to describe the spin-dependent reaction of\nexciton-charge complexes following the coherent manipulation of paramagnetic\ncenters through electron spin resonance. A general Hamiltonian is treated, and\nit is shown that the transition frequencies and resonance positions of the\nexciton-polaron complex can be used to estimate inter-species coupling. This\nwork also provides a general formalism for analysing multi-pulse experiments\nwhich can be used to extract relaxation and transport rates.",
        "positive": "Harnessing nuclear spin polarization fluctuations in a semiconductor\n  nanowire: Soon after the first measurements of nuclear magnetic resonance (NMR) in a\ncondensed matter system, Bloch predicted the presence of statistical\nfluctuations proportional to $1/\\sqrt{N}$ in the polarization of an ensemble of\n$N$ spins. First observed by Sleator et al., so-called \"spin noise\" has\nrecently emerged as a critical ingredient in nanometer-scale magnetic resonance\nimaging (nanoMRI). This prominence is a direct result of MRI resolution\nimproving to better than 100 nm^3, a size-scale in which statistical spin\nfluctuations begin to dominate the polarization dynamics. We demonstrate a\ntechnique that creates spin order in nanometer-scale ensembles of nuclear spins\nby harnessing these fluctuations to produce polarizations both larger and\nnarrower than the natural thermal distribution. We focus on ensembles\ncontaining ~10^6 phosphorus and hydrogen spins associated with single InP and\nGaP nanowires (NWs) and their hydrogen-containing adsorbate layers. We monitor,\ncontrol, and capture fluctuations in the ensemble's spin polarization in\nreal-time and store them for extended periods. This selective capture of large\npolarization fluctuations may provide a route for enhancing the weak magnetic\nsignals produced by nanometer-scale volumes of nuclear spins. The scheme may\nalso prove useful for initializing the nuclear hyperfine field of electron spin\nqubits in the solid-state."
    },
    {
        "anchor": "Plasmonic shock waves and solitons in a nanoring: We apply the hydrodynamic theory of electron liquid to demonstrate that a\ncircularly polarized radiation induces the diamagnetic, helicity-sensitive dc\ncurrent in a ballistic nanoring. This current is dramatically enhanced in the\nvicinity of plasmonic resonances. The resulting magnetic moment of the nanoring\nrepresents a giant increase of the inverse Faraday effect. With increasing\nradiation intensity, linear plasmonic excitations evolve into the strongly\nnon-linear plasma shock waves. These excitations produce a series of the well\nresolved peaks at the THz frequencies. We demonstrate that the plasmonic wave\ndispersion transforms the shock waves into solitons. The predicted effects\nshould enable multiple applications in a wide frequency range (from the\nmicrowave to terahertz band) using optically controlled ultra low loss\nelectric, photonic and magnetic devices.",
        "positive": "Higher-order topological insulators in synthetic dimensions: Conventional topological insulators support boundary states that have one\ndimension lower than the bulk system that hosts them, and these states are\ntopologically protected due to quantized bulk dipole moments. Recently,\nhigher-order topological insulators have been proposed as a way of realizing\ntopological states that are two or more dimensions lower than the bulk, due to\nthe quantization of bulk quadrupole or octupole moments. However, all these\nproposals as well as experimental realizations have been restricted to\nreal-space dimensions. Here we construct photonic higher-order topological\ninsulators (PHOTI) in synthetic dimensions. We show the emergence of a\nquadrupole PHOTI supporting topologically protected corner modes in an array of\nmodulated photonic molecules with a synthetic frequency dimension, where each\nphotonic molecule comprises two coupled rings. By changing the phase difference\nof the modulation between adjacently coupled photonic molecules, we predict a\ndynamical topological phase transition in the PHOTI. Furthermore, we show that\nthe concept of synthetic dimensions can be exploited to realize even\nhigher-order multipole moments such as a 4th order hexadecapole (16-pole)\ninsulator, supporting 0D corner modes in a 4D hypercubic synthetic lattice that\ncannot be realized in real-space lattices."
    },
    {
        "anchor": "Theory of hopping conduction in arrays of doped semiconductor\n  nanocrystals: The resistivity of a dense crystalline array of semiconductor nanocrystals\n(NCs) depends in a sensitive way on the level of doping as well as on the NC\nsize and spacing. The choice of these parameters determines whether electron\nconduction through the array will be characterized by activated\nnearest-neighbor hopping or variable-range hopping (VRH). Thus far, no general\ntheory exists to explain how these different behaviors arise at different\ndoping levels and for different types of NCs. In this paper we examine a simple\ntheoretical model of an array of doped semiconductor NCs that can explain the\ntransition from activated transport to VRH. We show that in sufficiently small\nNCs, the fluctuations in donor number from one NC to another provide sufficient\ndisorder to produce charging of some NCs, as electrons are driven to vacate\nhigher shells of the quantum confinement energy spectrum. This\nconfinement-driven charging produces a disordered Coulomb landscape throughout\nthe array and leads to VRH at low temperature. We use a simple computer\nsimulation to identify different regimes of conduction in the space of\ntemperature, doping level, and NC diameter. We also discuss the implications of\nour results for large NCs with external impurity charges and for NCs that are\ngated electrochemically.",
        "positive": "The quantum mechanical probability density and probability current\n  density operators in the Pauli theory: We present systematic construction of probability and probability current\ndensities operators for one-band single particle Pauli equations starting from\nthe operators in Dirac electron model within Second Quantized Approach. These\noperators are of importance as in probability interpretation of experimental\ndata, so in establishing of boundary conditions. It is shown that derived\noperators differ significally from their convential Schrodinger-type\ncounterparts. The generalization of continuity equation for probability density\nunder external perturbations and physical meaning of additional source terms is\ndiscussed. The presented approach can be useful in analysis of carriers\ndynamics described within generic multicomponent $\\vec{k} \\cdot \\vec{p}$\nHamiltonians in Envelope Function Approximation (EFA)."
    },
    {
        "anchor": "Topological stability of Majorana zero-modes in\n  superconductor-topological insulator systems: We derive an index theorem for zero-energy Majorana fermion modes in a\nsuperconductor-topological insulator system in both two and three dimensions,\nwhich is valid for models with chiral symmetry as well as particle-hole\nsymmetry. For more generic models without chiral symmetry, we suggest that\nMajorana zero-modes are classified by Z$_2$.",
        "positive": "Persistence of symmetry-protected Dirac points at the surface of the\n  topological crystalline insulator SnTe upon impurity doping: We investigate the effect of a non-magnetic donor impurity located at the\nsurface of the SnTe topological crystalline insulator. In particular, the\nchanges on the surface states due to a Sb impurity atom are analyzed by means\nof ab initio simulations of pristine and impurity-doped SnTe. Both\nsemi-infinite and slab geometries are considered within the first-principles\napproach. Furthermore, minimal and Green's function continuum models are\nproposed with the same goal. We find that the Dirac cones are shifted down in\nenergy upon doping; this shift strongly depends on the position of the impurity\nwith respect to the surface. In addition, we observe that the width of the\nimpurity band presents an even-odd behavior by varying the position of the\nimpurity. This behavior is related to the position of the nodes of the wave\nfunction with respect to the surface, and hence it is a manifestation of\nconfinement effects. We compare slab and semi-infinite geometries within the ab\ninitio approach, demonstrating that the surface states remain gapless and their\nspin textures are unaltered in the doped semi-infinite system. In the slab\ngeometry, a gap opens due to hybridization of the states localized at opposite\nsurfaces. Finally, by means of a continuum model, we extrapolate our results to\narbitrary positions of the impurity, clearly showing a non-monotonic behavior\nof the Dirac cone."
    },
    {
        "anchor": "Feedback controlled heat transport in quantum devices: Theory and solid\n  state experimental proposal: A theory of feedback controlled heat transport in quantum systems is\npresented. It is based on modelling heat engines as driven multipartite systems\nsubject to projective quantum measurements and measurement-conditioned unitary\nevolutions. The theory unifies various results presented in the previous\nliterature. Feedback control breaks time reversal invariance. This in turn\nresults in the fluctuation relation not being obeyed. Its restoration occurs by\nan appropriate accounting of the information gain and information use via\nmeasurements and feedback. We further illustrate an experimental proposal for\nthe realisation of a Maxwell demon using superconducting circuits and single\nphoton on-chip calorimetry. A two level qubit acts as a trapdoor which,\nconditioned on its state is coupled to either a hot resistor or a cold one. The\nfeedback mechanism alters the temperatures felt by the qubit and can result in\nan effective inversion of temperature gradient, where heat flows from cold to\nhot thanks to information gain and use",
        "positive": "Nongalvanic thermometry for ultracold two-dimensional electron domains: Measuring the temperature of a two-dimensional electron gas at temperatures\nof a few mK is a challenging issue, which standard thermometry schemes may fail\nto tackle. We propose and analyze a nongalvanic thermometer, based on a quantum\npoint contact and quantum dot, which delivers virtually no power to the\nelectron system to be measured."
    },
    {
        "anchor": "Observation of Majorana Fermions in Ferromagnetic Atomic Chains on a\n  Superconductor: Majorana fermions are predicted to localize at the edge of a topological\nsuperconductor, a state of matter that can form when a ferromagnetic system is\nplaced in proximity to a conventional superconductor with strong spin-orbit\ninteraction. With the goal of realizing a one-dimensional topological\nsuperconductor, we have fabricated ferromagnetic iron (Fe) atomic chains on the\nsurface of superconducting lead (Pb). Using high-resolution spectroscopic\nimaging techniques, we show that the onset of superconductivity, which gaps the\nelectronic density of states in the bulk of the Fe chains, is accompanied by\nthe appearance of zero energy end states. This spatially resolved signature\nprovides strong evidence, corroborated by other observations, for the formation\nof a topological phase and edge-bound Majorana fermions in our atomic chains.",
        "positive": "Detuning-dependent narrowing of Mollow triplet lines of driven quantum\n  dots: We study the two-time correlation function and the resonance fluorescence\nspectrum of a semiconductor quantum dot excited by a strong off-resonant laser\npulse. The obtained analytical expressions exhibit a specific\ndetuning-dependent damping of Rabi oscillations of the dressed quantum dot as\nwell as a detuning-dependent width of Mollow-triplet lines. In the absence of\npure dephasing, the central peak of the triplet is broadened, upon increasing\ndetuning, but the blue and red side peaks are narrowed. We demonstrate that\npure dephasing processes can invert these dependences. A crossover between the\nregimes of detuning-dependent narrowing and broadening of the side and central\npeaks is identified. The predicted effects are consistent with resent\nexperimental results and numerical calculations."
    },
    {
        "anchor": "Growth of Oriented Au Nanostructures: Role of Oxide at the Interface: We report on the formation of oriented gold nano structures on Si(100)\nsubstrate by annealing procedures in low vacuum (\\approx10-2 mbar) and at high\ntemperature (\\approx 975^{\\circ} C). Various thicknesses of gold films have\nbeen deposited with SiOx (using high vacuum thermal evaporation) and without\nSiOx (using molecular beam epitaxy) at the interface on Si(100). Electron\nmicroscopy measurements were performed to determine the morphology, orientation\nof the structures and the nature of oxide layer. Interfacial oxide layer, low\nvacuum and high temperature annealing conditions are found to be necessary to\ngrow oriented gold structures. These gold structures can be transferred by\nsimple scratching method.",
        "positive": "Spin resonance under topological driving fields: We study the dynamics of a localized spin-1/2 driven by a time-periodic\nmagnetic field that undergoes a topological transition. Despite the strongly\nnon-adiabatic effects dominating the spin dynamics, we find that the field's\ntopology appears clearly imprinted in the Floquet spin states through an\neffective Berry phase emerging in the quasienergy. This has remarkable\nconsequences on the spin resonance condition suggesting a whole new class of\nexperiments to spot topological transitions in the dynamics of spins and other\ntwo-level systems, from nuclear magnetic resonance to strongly-driven\nsuperconducting qubits."
    },
    {
        "anchor": "Charge and Spin Transport at the Quantum Hall Edge of Graphene: Landau level bending near the edge of graphene, described using 2d Dirac\nequation, provides a microscopic framework for understanding the quantum Hall\nEffect (QHE) in this material. We review properties of the QHE edge states in\ngraphene, with emphasis on the novel phenomena that arise due to Dirac\ncharacter of electronic states. A method of mapping out the dispersion of the\nedge states using scanning tunneling probes is proposed. The Zeeman splitting\nof Landau levels is shown to create a particularly interesting situation around\nthe Dirac point, where it gives rise to counter-circulating modes with opposite\nspin. These chiral spin modes lead to a rich variety of spin transport\nphenomena, including spin Hall effect, spin filtering and injection, and\nelectric detection of spin current. The estimated Zeeman spin gap, enhanced by\nexchange, of a few hundred Kelvin, makes graphene an attractive system for\nspintronics. Comparison to recent transport measurements near nu=0 is\npresented.",
        "positive": "Kelvin probe force microscopy by direct dissipative electrostatic force\n  modulation: We report a new experimental technique for Kelvin probe force microscopy\n(KPFM) using the dissipation signal of frequency modulation atomic force\nmicroscopy for bias voltage feedback. It features a simple implementation and\nfaster scanning as it requires no low frequency modulation. The dissipation is\ncaused by the oscillating electrostatic force that is coherent with the tip\noscillation, which is induced by a sinusoidally oscillating voltage applied\nbetween the tip and sample. We analyzed the effect of the phase of the\noscillating force on the frequency shift and dissipation and found that the\nrelative phase of 90$^\\circ$ that causes only the dissipation is the most\nappropriate for KPFM measurements. The present technique requires a\nsignificantly smaller ac voltage amplitude by virtue of enhanced force\ndetection due to the resonance enhancement and the use of fundamental flexural\nmode oscillation for electrostatic force detection. This feature will be of\ngreat importance in the electrical characterizations of technically relevant\nmaterials whose electrical properties are influenced by the externally applied\nelectric field as is the case in semiconductor electronic devices."
    },
    {
        "anchor": "Semiclassical kinetic theory for systems with non-trivial quantum\n  geometry and the expectation value of physical quantities: Starting from the Keldysh theory, for a general low energy $N$-band\nHamiltonian in the clean limit, we perform a manifestly $\\smash{U(1) \\times\nSU(N)}$ gauge invariant semiclassical expansion. A generalized Berry curvature\ntensor is shown to control a redistribution of spectral weights. New\nexpressions for certain physical quantities ensue, establishing the limits of a\npreviously proposed correction to the density of states. In the two-band case,\nwe derive a completely general semiclassical kinetic theory including all\n$O(\\hbar)$ quantum corrections. As an application, we show how one can recover,\nout of a single simple calculation, the chiral anomaly, intrinsic anomalous\nHall conductivity and chiral magnetic effect, in all generality. The\ndemonstrated flexibility and efficiency of our formalism derives from the\ninsulation it provides from the underlying complexity of the quantum kinetics,\nnotwithstanding its rigorous connection to this deeper level.",
        "positive": "Diffusive transport in Weyl semimetals: Diffusion, a ubiquitous phenomenon in nature, is a consequence of particle\nnumber conservation and locality, in systems with sufficient damping. In this\npaper we consider diffusive processes in the bulk of Weyl semimetals, which are\nexotic quantum materials, recently of considerable interest. In order to do\nthis, we first explicitly implement the analytical scheme by which disorder\nwith anisotropic scattering amplitude is incorporated into the diagrammatic\nresponse-function formalism for calculating the `diffuson'. The result thus\nobtained is consistent with transport coefficients evaluated from the Boltzmann\ntransport equation or the renormalized uniform current vertex calculation, as\nit should be. We thus demonstrate that the computation of the diffusion\ncoefficient should involve the transport lifetime, and not the quasiparticle\nlifetime. Using this method, we then calculate the density response function in\nWeyl semimetals and discover an unconventional diffusion process that is\nsignificantly slower than conventional diffusion. This gives rise to relaxation\nprocesses that exhibit stretched exponential decay, instead of the usual\nexponential diffusive relaxation. This result is then explained using a model\nof thermally excited quasiparticles diffusing with diffusion coefficients which\nare strongly dependent on their energies. We elucidate the roles of the various\nenergy and time scales involved in this novel process and propose an experiment\nby which this process may be observed."
    },
    {
        "anchor": "Can layered-structure effects be observed, if the Fermi surface is\n  closed?: By analyzing the longitudinal conductivity in a quantizing magnetic field\ndirected perpendicularly to the crystal lattice layers, it has been\ndemonstrated that the layered-structure effects can be observed not only in\ncrystals with highly open Fermi surfaces, as was conventionally believed\nearlier, but also in crystals with closed ones. The calculations were carried\nout in the constant-relaxation-time approximation. In weak magnetic fields,\nlayered-structure effects manifest themselves as a phase retardation of\nShubnikov--de Haas oscillations and a certain increase of the relative\ncontribution made by the latter. In the range of high magnetic fields, there\nexists an optimal interval, in which the layered-structure effects reveal\nthemselves in the form of a sharp non-monotonous dependence of conductivity on\nthe magnetic field. In addition, it has been shown that the layered-structure\neffects result in a decrease of the proportionality factor between the\nmagnetoresistance and the magnetic induction in the longitudinal Kapitsa\neffect. The longitudinal conductivity of layered crystals in ultra-quantum\nmagnetic fields has also been analyzed. It is shown that the following\ndependences of the magnetoresistance on the magnetic field can be obtained,\ndepending on the model used for the filling of the single Landau subband and on\nwhether the longitudinal conductivity is considered to be of either the drift\nor diffusion type: $\\rho_{zz}\\propto TB^{2}$,\\ $\\rho_{zz}\\propto B^{3}$, and\n$\\rho_{zz}\\propto B^{4}$.",
        "positive": "Nonequilibrium valley polarization in graphene nanoconstrictions: We recently shown, using tight-binding calculations, that nonequilibrium\nvalley polarization can be realized in graphene, when the current is injected\nthrough \"valley filter\": a ballistic point contact with zigzag edges. Here we\ndemonstrate, that the effect is surprisingly robust against changing the\ncrystallographic orientation of the filter axis. Namely, the output current\nremains polarized unless a point contact has perfect armchair edges, at which\ntwo subblattices are equally represented. The polarization is inverted when the\nfilter orientation crosses the amchair line and, subsequently, dominating\nsubblattice index of terminal atoms changes. In a bended graphene strip, the\nvalley-polarized current can be directed towards one edge providing a\ntheoretical possibility to observe a zero-magnetic-field analogue of the\nwell-known Hall effect. For the valley valve, build of two valley filters in\nseries and controlled elecrostatically by a gate voltage, the\nconductance-to-gate characteristic is inverted when $\\pi/3$ vertex is placed\nbetween two filters."
    },
    {
        "anchor": "Observations of $\u03bd=1$ Quantum Hall Effect and Inter-Band Effects of\n  Magnetic fields on Hall Conductivity in Organic Massless Dirac Fermion System\n  $\u03b1$-(BETS)$_2$I$_3$ under Pressure: We investigated the magnetoresistance and the Hall effect in an organic\nmassless Dirac fermion system $\\alpha$-(BETS)$_2$I$_3$ under pressure. The\nFermi energy of this system is slightly far away from the Dirac points, and\nthus the $\\nu =1$ quantum Hall state is realized in a low magnetic field at low\ntemperatures. Moreover, the experimental formula for chemical potential as a\nfunction of temperature is clarified. We succeeded in detecting the inter-band\neffects of the magnetic field on the Hall conductivity when the chemical\npotential passes the Dirac points.",
        "positive": "Linear and Non-linear Response of Lithographically Defined Plasmonic\n  Nanoantennas: We present numerical studies, nano-fabrication and optical characterization\nof bowtie nanoantennas demonstrating their superior performance with respect to\nthe electric field enhancement as compared to other Au nanoparticle shapes. For\noptimized parameters, we found mean intensity enhancement factors >2300x in the\nfeed-gap of the antenna, decreasing to 1300x when introducing a 5nm titanium\nadhesion layer. Using electron beam lithography we fabricated gold bowties on\nvarious substrates with feed-gaps and tip radii as small as 10nm. In\npolarization resolved measurement we experimentally observed a blue shift of\nthe surface plasmon resonance from 1.72eV to 1.35eV combined with a strong\nmodification of the electric field enhancement in the feed-gap. Under\nexcitation with a 100fs pulsed laser source, we observed non-linear light\nemission arising from two-photon photoluminescence and second harmonic\ngeneration from the gold. The bowtie nanoantenna shows a high potential for\noutstanding conversion efficiencies and the enhancement of other optical\neffects which could be exploited in future nanophotonic devices."
    },
    {
        "anchor": "Shell-resolved melting kinetics of an icosahedral cluster: Molecular dynamics calculations of the fluctuation of bond vibration revealed\nthe shell-resolved kinetics of surface melting of closed-shelled cluster\ncontaining 147atoms with Lennard-Jones type interaction. It is found that the\nsurface melting is imitated by the migrating of the vertex atoms and the\nmelting process can be divided into three major stages, i.e., vertex migrating,\nsurface melting, and general melting. Although the melting process of the LJ147\ncluster could be divided into discrete stages of shell-by-shell surface\nmelting, in general, there is still a continuous process of melting from the\nsurface to the core interior.",
        "positive": "Single-parameter pumping in graphene: We propose a quantum pump mechanism based on the particular properties of\ngraphene, namely chirality and bipolarity. The underlying physics is the\nexcitation of evanescent modes entering a potential barrier from one lead,\nwhile those from the other lead do not reach the driving region. This induces a\nlarge nonequilibrium current with electrons stemming from a broad range of\nenergies, in contrast to the narrow resonances that govern the corresponding\neffect in semiconductor heterostructures. Moreover, the pump mechanism in\ngraphene turns out to be robust, with a simple parameter dependence, which is\nbeneficial for applications. Numerical results from a Floquet scattering\nformalism are complemented with analytical solutions for small to moderate\ndriving."
    },
    {
        "anchor": "Single-shot measurement of triplet-singlet relaxation in a Si/SiGe\n  double quantum dot: We investigate the lifetime of two-electron spin states in a few-electron\nSi/SiGe double dot. At the transition between the (1,1) and (0,2) charge\noccupations, Pauli spin blockade provides a readout mechanism for the spin\nstate. We use the statistics of repeated single-shot measurements to extract\nthe lifetimes of multiple states simultaneously. At zero magnetic field, we\nfind that all three triplet states have equal lifetimes, as expected, and this\ntime is ~10 ms. At non-zero field, the T0 lifetime is unchanged, whereas the T-\nlifetime increases monotonically with field, reaching 3 seconds at 1 T.",
        "positive": "Unusually stable helical coil allotrope of phosphorus: We have identified an unusually stable helical coil allotrope of phosphorus.\nOur ab initio Density Functional Theory calculations indicate that the\nuncoiled, isolated straight 1D chain is equally stable as a monolayer of black\nphosphorus dubbed phosphorene. The coiling tendency and the attraction between\nadjacent coil segments add an extra stabilization energy of about 12 meV/atom\nto the coil allotrope, similar in value to the approximately 16 meV/atom\ninter-layer attraction in bulk black phosphorus. Thus, the helical coil\nstructure is essentially as stable as black phosphorus, the most stable\nphosphorus allotrope known to date. With an optimum radius of 2.4 nm, the\nhelical coil of phosphorus may fit well and even form inside wide carbon\nnanotubes."
    },
    {
        "anchor": "Kondo model for the \"0.7 anomaly\" in transport through a quantum point\n  contact: Experiments on quantum point contacts have highlighted an anomalous\nconductance plateau at $0.7 (2e^2/h)$, with features suggestive of the Kondo\neffect. Here we present an Anderson model for transport through a point contact\nwhich we analyze in the Kondo limit. Hybridization to the band increases\nabruptly with energy but decreases with valence, so that the background\nconductance and the Kondo temperature $T_K$ are dominated by different valence\ntransitions. This accounts for the high residual conductance above $T_K$. A\nspin-polarized current is predicted for Zeeman splitting $g^* \\mu_B B > k_B\nT_K,k_BT$.",
        "positive": "Multilayer graphene condenser microphone: Vibrating membranes are the cornerstone of acoustic technology, forming the\nbackbone of modern loudspeakers and microphones. Acoustic performance of\ncondenser microphone is derived mainly from the membrane's size and achievable\nstatic tension. The widely studied and available nickel has been the one of\ndominant membrane material for several decades. In this paper we introduce\nmultilayer graphene as membrane material for a condenser microphone. The\ngraphene device outperforms a high end commercial nickel-based microphone over\na significant part of the acoustic spectrum, with a larger than 10 dB\nenhancement of sensitivity. Our experimental results are supported with\nnumerical simulations, which show that a 300 layer thick graphene membrane\nunder maximum tension would offer excellent extension of the frequency range,\nup to 1 MHz, with similar sensitivity as commercial condenser microphones."
    },
    {
        "anchor": "Permanent magnetic moment in mesoscopic metals with spin-orbit\n  interaction: We argue that at zero temperature an isolated metal particle (or an AB ring)\nwith spin-orbit interaction and odd number of electrons will have a permanent\nmagnetic moment, even in zero magnetic field (flux). In a zero-field-cooled\nstate both the direction and the magnitude of the moment varies from particle\nto particle and averages to zero. In a field-cooled state it averages to $\\sim\n\\mu_{B}(k_{F}\\ell) ^{1/2}$. We argue that the permanent moment is due to an\nuncompensated electron in the last occupied (Fermi) level. We introduce an\neffective single-electron Hamiltonian which accounts for spin-orbit coupling.",
        "positive": "Hall field-induced resistance oscillations in Ge/SiGe quantum wells: We report on a magnetotransport study in a high-mobility 2D hole gas hosted\nin a pure Ge/SiGe quantum well subject to dc electric fields and high frequency\nmicrowave radiation. We find that under applied dc bias the differential\nresistivity exhibits a pronounced maximum at a magnetic field which increases\nlinearly with the applied current. We associate this maximum with the\nfundamental peak of Hall field-induced resistance oscillations (HIRO) which are\nknown to occur in 2D electron gases in GaAs/AlGaAs systems. After taking into\naccount the Dingle factor correction, we find that the position of the HIRO\npeak is well described by the hole effective mass $m^\\star \\approx 0.09\\,m_0$,\nobtained from microwave photoresistance in the same sample."
    },
    {
        "anchor": "Effect of weak disorder on delocalization properties of gapped graphene\n  superlattices: We study the effect of weak disorder on the delocalization properties of\ngapped graphene superlattice (SL) formed by periodically located rectangular\npotential barriers. We consider two types of the SLs: the SLs with uniform and\nnonuniform gap. Using the perturbative approach we obtain an analytical\nexpression for the inverse localization length (ILL) derived for the case of\nrandomly fluctuating geometric and energetic parameters. In the first case,\nwhen the barrier (well) width fluctuates around its mean value, the\ncorresponding equation for the ILL reveals the presence of the Fabry-Perot\nresonances, at which the localization length diverges. These resonances are\nexact, i.e., are stored in any degree of disorder. It has been found that the\nlocalization properties manifest stronger for the particles with energies lying\nin the non-resonant bands where our approach is extremely sensitive to the\ndegree of disorder. For the case of weakly fluctuating both barrier and well\nwidths we analytically obtain ILL taking correlations into account. The main\neffect of the correlations, which lead to an increase (or decrease) in the\nlocalization length, was revealed near the double resonance arising at\ncoincidence of two Fabry-Perot resonances associated with barrier and well\nwidths. The random fluctuations of the potential strength also lead to the\ndelocalization resonances. However, they exist only in a weak-disorder\napproximation. We found that, for an array composed of alternating strips of\ngapless and gapped graphene modifications these resonances can appear only for\nnormally incident particles in contrast to the SL with a uniform gap. For such\nparticles, the delocalization resonances occur also in the purely random\npotential. This means, in particular, that in the one-dimensional case, not all\nthe states of the massive Dirac particles are localized in the presence of weak\ndisorder.",
        "positive": "Transfer-matrix approach to the problem of electrical conduction through\n  a series of absorbers: Here we study incoherent transport through molecular wire treated as a linear\nchain of absorbers, where the phase-breaking processes are modeled by the use\nof imaginary point-like potentials. The calculations are performed within a\ntransfer-matrix method of the scattering theory. An analytic expression for the\ntransmission of a finite chain in obtained, while the electrical current is\nthen computed with the help of the Tsu-Esaki formula. In particular, it is\nshown that the maximal current dependence on the wire length is exponential."
    },
    {
        "anchor": "Measurement of the Transmission Phase through a Quantum Dot Embedded in\n  One Arm of an Electronic Mach-Zehnder Interferometer: We investigate an electronic Mach-Zehnder interferometer with high visibility\nin the quantum Hall regime. The superposition of the electrostatic potentials\nfrom a quantum point contact (QPC) and the residual disorder potential from\ndoping impurities frequently results in the formation of inadvertent quantum\ndots (QD) in one arm of the interferometer. This gives rise to resonances in\nthe QPC transmission characteristics. While crossing the QD resonance in\nenergy, the interferometer gains a phase shift of $\\pi$ in the interference\npattern.",
        "positive": "Switchable X-ray Orbital Angular Momentum from an Artificial Spin Ice: Artificial spin ices (ASI) have been widely investigated as magnetic\nmetamaterials with exotic properties governed by their geometries. In parallel,\ninterest in X-ray photon orbital angular momentum (OAM) has been rapidly\ngrowing. Here we show that a square ASI with a programmed topological defect, a\ndouble edge dislocation, imparts OAM to scattered X-rays. Unlike single\ndislocations, a double dislocation does not introduce magnetic frustration, and\nthe ASI equilibrates to its antiferromagnetic (AF) ground state. The\ntopological charge of the defect differs with respect to the structural and\nmagnetic order; thus, X-ray diffraction from the ASI produces photons with even\nand odd OAM quantum numbers at the structural and AF Bragg conditions,\nrespectively. The magnetic transitions of the ASI allow the AF OAM beams to be\nswitched on and off by modest variations of temperature and applied magnetic\nfield. These results demonstrate ASIs can serve as metasurfaces for\nreconfigurable X-ray optics that could enable selective probes of electronic\nand magnetic properties."
    },
    {
        "anchor": "Many-body effects in doped graphene on a piezoelectric substrate: We investigate the many-body properties of graphene on top of a piezoelectric\nsubstrate, focusing on the interaction between the graphene electrons and the\npiezoelectric acoustic phonons. We calculate the electron and phonon\nself-energies as well as the electron mobility limited by the substrate\nphonons. We emphasize the importance of the proper screening of the\nelectron-phonon vertex and discuss the various limiting behaviors as a function\nof electron energy, temperature, and doping level. The effect on the graphene\nelectrons of the piezoelectric acoustic phonons is compared with that of the\nintrinsic deformation acoustic phonons of graphene. Substrate phonons tend to\ndominate over intrinsic ones for low doping levels at high and low\ntemperatures.",
        "positive": "Heat dissipation and its relation to thermopower in single-molecule\n  junctions: Motivated by recent experiments [Lee et al. Nature 498, 209 (2013)], we\npresent here a detailed theoretical analysis of the Joule heating in\ncurrent-carrying single-molecule junctions. By combining the Landauer approach\nfor quantum transport with ab initio calculations, we show how the heating in\nthe electrodes of a molecular junction is determined by its electronic\nstructure. In particular, we show that in general the heat is not equally\ndissipated in both electrodes of the junction and it depends on the bias\npolarity (or equivalently on the current direction). These heating asymmetries\nare intimately related to the thermopower of the junction as both these\nquantities are governed by very similar principles. We illustrate these ideas\nby analyzing single-molecule junctions based on benzene derivatives with\ndifferent anchoring groups. The close relation between heat dissipation and\nthermopower provides general strategies for exploring fundamental phenomena\nsuch as the Peltier effect or the impact of quantum interference effects on the\nJoule heating of molecular transport junctions."
    },
    {
        "anchor": "Fano resonance via bonding and antibonding states in\n  nonadiabatically-pumped double-quantum-well systems: In this work, transport properties of the nonadiabatically pumped\ndouble-quantum-well (DQW) structure are studied. Different from a single\nquantum well, band mixing in the DQW generates bonding and antibonding states,\nwhose wave functions have different spatial symmetry. By applying a\ntime-dependent electric potential to the two well regions simultaneously,\nFloquet sidebands are formed, which constitutes additional quantum tunneling\npaths. When one of the Floquet sidebands coincides with the bonding or\nantibonding quasibound states within the DQW structure, sharp Fano resonances\nare found in the transmission coefficients as well as in the differential shot\nnoise spectra. While such Fano resonances originate from quantum interference,\ntheir shapes are strikingly different for transport via the bonding state and\nvia the antibonding state. The Fano resonance via the even-parity bonding state\nshows a perfect transmission followed by a total reflection and the Fano\nresonance via the odd-parity antibonding state has a reversed symmetry and\nshows a total reflection before a perfect transmission.",
        "positive": "Interaction-driven spin precession in quantum-dot spin valves: We analyze spin-dependent transport through spin valves composed of an\ninteracting quantum dot coupled to two ferromagnetic leads. The spin on the\nquantum dot and the linear conductance as a function of the relative angle\n$\\theta$ of the leads' magnetization directions is derived to lowest order in\nthe dot-lead coupling strength. Due to the applied bias voltage spin\naccumulates on the quantum dot, which for finite charging energy experiences a\ntorque, resulting in spin precession. The latter leads to a non-trivial,\ninteraction-dependent, $\\theta$-dependence of the conductance. In particular,\nwe find that the spin-valve effect is reduced for all $\\theta \\neq \\pi$."
    },
    {
        "anchor": "Size dependent line broadening in the emission spectra of single GaAs\n  quantum dots: Impact of surface charges on spectral diffusion: Making use of droplet epitaxy, we systematically controlled the height of\nself-assembled GaAs quantum dots by more than one order of magnitude. The\nphotoluminescence spectra of single quantum dots revealed the strong dependence\nof the spectral linewidth on the dot height. Tall dots with a height of ~30 nm\nshowed broad spectral peaks with an average width as large as ~5 meV, but\nshallow dots with a height of ~2 nm showed resolution-limited spectral lines\n(<120 micro eV). The measured height dependence of the linewidths is in good\nagreement with Stark coefficients calculated for the experimental shape\nvariation. We attribute the microscopic source of fluctuating electric fields\nto the random motion of surface charges at the vacuum-semiconductor interface.\nOur results offer guidelines for creating frequency-locked photon sources,\nwhich will serve as key devices for long-distance quantum key distribution.",
        "positive": "Thermoelectricity without absorbing energy from the heat sources: We analyze the power output of a quantum dot machine coupled to two\nelectronic reservoirs via thermoelectric contacts, and to two thermal\nreservoirs - one hot and one cold. This machine is a nanoscale analogue of a\nconventional thermocouple heat-engine, in which the active region being heated\nis unavoidably also exchanging heat with its cold environment. Heat exchange\nbetween the dot and the thermal reservoirs is treated as a capacitive coupling\nto electronic fluctuations in localized levels, modeled as two additional\nquantum dots. The resulting multiple-dot setup is described using a master\nequation approach. We observe an \"exotic\" power generation, which remains\nfinite even when the heat absorbed from the thermal reservoirs is zero (in\nother words the heat coming from the hot reservoir all escapes into the cold\nenvironment). This effect can be understood in terms of a non-local effect in\nwhich the heat flow from heat source to the cold environment generates power\nvia a mechanism which we refer to as Coulomb heat drag. It relies on the fact\nthat there is no relaxation in the quantum dot system, so electrons within it\nhave a non-thermal energy distribution. More poetically, one can say that we\nfind a spatial separation of the first-law of thermodynamics (heat to work\nconversion) from the second-law of thermodynamics (generation of entropy). We\npresent circumstances in which this non-thermal system can generate more power\nthan any conventional macroscopic thermocouple (with local thermalization),\neven when the latter works with Carnot efficiency."
    },
    {
        "anchor": "Effective field theory of the disordered Weyl semimetal: In disordered Weyl semimetals, mechanisms of topological origin lead to the\nprotection against Anderson localization, and at the same time to different\ntypes of transverse electromagnetic response -- the anomalous Hall, and chiral\nmagnetic effect. We here apply field theory methods to discuss the\nmanifestation of these phenomena at length scales which are beyond the scope of\ndiagrammatic perturbation theory. Specifically we show how an interplay of\nsymmetry breaking and the chiral anomaly leads to a field theory containing two\ntypes of topological terms. Generating the unconventional response coefficients\nof the system, these terms remain largely unaffected by disorder, i.e.\ninformation on the chirality of the system remains visible even at large length\nscales.",
        "positive": "Skyrmion-based Magnetic Traps for Ultracold Atoms: We show that the stray field generated by isolated magnetic skyrmions can be\nused to trap ultracold atoms. Specially, ring-shaped and double-well trapping\npotentials for ultracold atoms can be created by combining the field from two\nisolated skyrmions. The geometry size, potential barrier, trapping frequency\nand Majorana loss rate of these magnetic traps can be tuned by the external\nmagnetic field or device configuration. The results here could be useful to\ndevelop atomtronics devices by manipulating the magnetic skyrmions with modern\nspintronics techniques."
    },
    {
        "anchor": "Bloch point nanospheres for the design of magnetic traps: Through micromagnetic simulations, this work analyzes the stability of Bloch\npoints in magnetic nanospheres and the possibility of using an array of such\nparticles to compose a system with the features of a magnetic trap. We show\nthat a BP can be nucleated as a metastable configuration in a relatively wide\nrange of the nanosphere radius compared to a quasi-uniform and vortex state. We\nalso show that the stabilized Bloch point generates a quadrupolar magnetic\nfield outside it, from which we analyze the field profile of different arrays\nof these nanospheres to show that the obtained magnetic field shares the\nfeatures of magnetic traps. Some of the highlights of the proposed magnetic\ntraps rely on the magnetic field gradients achieved, which are orders of\nmagnitude higher than standard magnetic traps, and allow three-dimensional\ntrapping. Our results could be useful in trapping particles through the\nintrinsic magnetization of ferromagnetic nanoparticles while avoiding the\ncommonly used mechanisms associated with Joule heating.",
        "positive": "All-electrical manipulation of electron spin by the spin-orbit\n  interaction in a semiconductor nanotube: analytical results: A possibility of controlled manipulation of electron spin states has been\ninvestigated for a cylindrical two-dimensional electron gas confined in a\nsemiconductor nanotube/cylindrical nanowire with the Rashba spin-orbit\ninteraction. We present analytical solutions for the two limiting cases, in\nwhich the spin-orbit interaction results from (A) the radial electric field and\n(B) the electric field applied along the axis z of the nanotube. In case (A),\nthe superposition of the two lowest-energy bands corresponding to the opposite\nspins leads to the precession of electron spin around the nanowire axis. We\nhave found that the direction of the spin precession changes from clockwise to\ncounterclockwise if the energy of the injected electron achieves the value\ncorresponding to the crossing of energy levels associated with the two\ncomponents of the superposition state. In case (B), we have obtained the damped\noscillations of the z spin component with the period that changes as a function\nof the coordinate z. We have also shown that the damped oscillations of the\naverage value of the z spin component form beats localized along the nanowire\naxis."
    },
    {
        "anchor": "Transport across a carbon nanotube quantum dot contacted with\n  ferromagnetic leads: experiment and non-perturbative modeling: We present measurements of tunneling magneto-resistance (TMR) in single-wall\ncarbon nanotubes attached to ferromagnetic contacts in the Coulomb blockade\nregime. Strong variations of the TMR with gate voltage over a range of four\nconductance resonances, including a peculiar double-dip signature, are\nobserved. The data is compared to calculations in the \"dressed second order\"\n(DSO) framework. In this non-perturbative theory, conductance peak positions\nand linewidths are affected by charge fluctuations incorporating the properties\nof the carbon nanotube quantum dot and the ferromagnetic leads. The theory is\nable to qualitatively reproduce the experimental data.",
        "positive": "Laterally proximized aluminum tunnel junctions: This letter presents experiments on junctions fabricated by a new technique\nthat enables the use of high quality aluminum oxide tunnel barriers with normal\nmetal electrodes at low temperatures. Inverse proximity effect is applied to\ndiminish the superconductivity of an aluminum dot through a clean lateral\nconnection to a normal metal electrode. To demonstrate the effectiveness of\nthis method, fully normal-state single electron transistors (SET) and normal\nmetal-insulator-superconductor (NIS) junctions applying proximized Al junctions\nwere fabricated. The transport characteristics of the junctions were similar to\nthose obtained from standard theoretical models of regular SETs and NIS\njunctions."
    },
    {
        "anchor": "Spin control in semiconductor quantum wires: We show that spin-flip rotation in a semiconductor quantum wire, caused by\nthe Rashba and the Dresselhaus interactions (both of arbitrary strengths), can\nbe suppressed by dint of an in-plane magnetic field. We found a new type of\nsymmetry, which arises at a particular set of intensity and orientation of the\nmagnetic field and explains this suppression. Based on our findings, we propose\na transport experiment to measure the strengths of the Rashba and the\nDresselhaus interactions.",
        "positive": "Proximity-induced Shiba states in a molecular junction: Superconductors containing magnetic impurities exhibit intriguing phenomena\nderived from the competition between Cooper pairing and Kondo screening. At the\nheart of this competition are the Yu-Shiba-Rusinov (Shiba) states which arise\nfrom the pair breaking effects a magnetic impurity has on a superconducting\nhost. Hybrid superconductor-molecular junctions offer unique access to these\nstates but the added complexity in fabricating such devices has kept their\nexploration to a minimum. Here, we report on the successful integration of a\nmodel spin 1/2 impurity, in the form of a neutral and stable all organic\nradical molecule, in proximity-induced superconducting break-junctions. Our\nmeasurements reveal excitations which are characteristic of a spin-induced\nShiba state due to the radical's unpaired spin strongly coupled to a\nsuperconductor. By virtue of a variable molecule-electrode coupling, we access\nboth the singlet and doublet ground states of the hybrid system which give rise\nto the doublet and singlet Shiba excited states, respectively. Our results show\nthat Shiba states are a robust feature of the interaction between a\nparamagnetic impurity and a proximity-induced superconductor where the excited\nstate is mediated by correlated electron-hole (Andreev) pairs instead of Cooper\npairs."
    },
    {
        "anchor": "Landau levels in spin-orbit coupling proximitized graphene: bulk states: We study the magnetic-field dependence of Landau levels in graphene\nproximitized by large spin-orbit coupling materials, such as transition-metal\ndichalcogenides or topological insulators. In addition to the Rashba coupling,\ntwo types of intrinsic spin-orbit interactions, uniform (Kane-Mele type) and\nstaggered (valley Zeeman type), are included, to resolve their interplay with\nmagnetic orbital effects. Employing a continuum model approach, we derive\nanalytic expressions for low-energy Landau levels, which can be used to extract\nlocal orbital and spin-orbit coupling parameters from scanning probe\nspectroscopy experiments. We compare different parameter regimes to identify\nfingerprints of relative and absolute magnitudes of intrinsic spin-orbit\ncoupling in the spectra. The inverted band structure of graphene proximitized\nby WSe$_2$ leads to an interesting crossing of Landau states across the bulk\ngap at a crossover field, providing insights into the size of Rashba spin-orbit\ncoupling. Landau level spectroscopy can help to resolve the type and signs of\nthe intrinsic spin-orbit coupling by analyzing the symmetry in energy and\nnumber of crossings in the Landau fan chart. Finally, our results suggest that\nthe strong response to the magnetic field of Dirac electrons in proximitized\ngraphene can be associated with extremely large self-rotating magnetic moments.",
        "positive": "Effect of a in-plane magnetic field on the microwave assisted\n  magnetotransport in a two-dimensional electron system: In this work we present a theoretical approach to study the effect of an\nin-plane (parallel) magnetic field on the microwave-assisted transport\nproperties of a two-dimensional electron system. Previous experimental\nevidences show that microwave-induced resistance oscillations and zero\nresistance states are differently affected depending on the experimental\nset-up: two magnetic fields (two-axis magnet) or one tilted magnetic field. In\nthe first case, experiments report a clear quenching of resistance oscillations\nand zero resistance states. In a tilted field, one obtains oscillations\ndisplacement and quenching but the latter is unbalanced and less intense. In\nour theoretical proposal we explain these results in terms of the\nmicrowave-driven harmonic motion performed by the electronic orbits and how\nthis motion is increasingly damped by the in-plane field."
    },
    {
        "anchor": "A simple analytical description for the cross-tie domain wall structure: A closed form analytical expression for the magnetization vector distribution\nwithin the cross-tie domain wall in an isotropic ferromagnetic thin film is\ngiven. The expression minimizes the exchange energy functional exactly, and the\nmagnetostatic energy by means of an adjustable parameter (wall width). The\nequilibrium value of the wall width and the film thickness corresponding to the\ntransition between the N{\\'e}el and the cross-tie walls are calculated. The\nresults are compared with the recent experiments and are in good qualitative\nagreement.",
        "positive": "Non-Abelian SU(2) gauge fields through density-wave order and strain in\n  graphene: Spatially varying strain patterns can qualitatively alter the electronic\nproperties of graphene, acting as effective valley-dependent magnetic fields\nand giving rise to pseudo-Landau-level (PLL) quantization. Here, we show that\nthe strain-induced magnetic field is one component of an SU(2) non-Abelian\ngauge field within the low-energy theory of graphene, and identify the other\ntwo components as period-3 charge-density waves. We show that these\ndensity-waves, if spatially varied, give rise to PLL quantization. We also\nargue that strain-induced magnetic fields can induce density-wave order in\ngraphene, thus dynamically gapping out the lowest PLL; moreover, the ordering\nshould generically be accompanied by dislocations. We discuss experimental\nsignatures of these effects."
    },
    {
        "anchor": "Pressure coefficients of Raman modes of carbon nanotubes resolved by\n  chirality: Environmental effect on graphene sheet: Studies of the mechanical properties of single-walled carbon nanotubes are\nhindered by the availability only of ensembles of tubes with a range of\ndiameters. Tunable Raman excitation spectroscopy picks out identifiable tubes.\nUnder high pressure, the radial breathing mode shows a strong environmental\neffect shown here to be largely independent of the nature of the environment .\nFor the G-mode, the pressure coefficient varies with diameter consistent with\nthe thick-wall tube model. However, results show an unexpectedly strong\nenvironmental effect on the pressure coefficients. Reappraisal of data for\ngraphene and graphite gives the G-mode Grueuneisen parameter gamma = 1.34 and\nthe shear deformation parameter beta = 1.34.",
        "positive": "Characteristic time of transition from write error to retention error in\n  voltage-controlled magnetoresistive random-access memory: Voltage controlled magnetoresistive random access memory (VC MRAM) is a\npromising candidate for a future low-power high-density memory. The main causes\nof bit errors in VC MRAM are write error and retention error. As the size of\nthe memory cell decreases, the data retention time decreases, which causes a\ntransition from the write-error-dominant region to the retention-error-dominant\nregion at a certain operating time. Here we introduce the characteristic time\nof the transition from the write-error-dominant region to the\nretention-error-dominant region and analyze how the characteristic time depends\non the effective anisotropy constant, $K_{0}$. The characteristic time is\napproximately expressed as $t_{\\rm c} = 2\\, w\\, \\tau$, where $w$ is the write\nerror rate, and $\\tau$ is the relaxation time derived by Kalmkov [J. Appl.\nPhys. 96, (2004) 1138-1145]. We show that for large $K_{0}$, $t_{\\rm c}$\nincreases with increase of $K_{0}$ similar to $\\tau$. The characteristic time\nis a key parameter for designing the VC MRAM for the variety of applications\nsuch as machine learning and artificial intelligence."
    },
    {
        "anchor": "Nuclear spin dynamics, noise, squeezing and entanglement in box model: We obtain a compact analytical solution for the nonlinear equation for the\nnuclear spin dynamics in the central spin box model in the limit of many\nnuclear spins. The total nuclear spin component along the external magnetic\nfield is conserved and the two perpendicular components precess or oscillate\ndepending on the electron spin polarization, with the frequency, determined by\nthe nuclear spin polarization. As applications of our solution, we calculate\nthe nuclear spin noise spectrum and describe the effects of nuclear spin\nsqueezing and many body entanglement in the absence of a system excitation.",
        "positive": "Quantum percolation in quantum spin Hall antidot systems: We study the influences of antidot-induced bound states on transport\nproperties of two- dimensional quantum spin Hall insulators. The bound\nstatesare found able to induce quantum percolation in the originally insulating\nbulk. At some critical antidot densities, the quantum spin Hall phase can be\ncompletely destroyed due to the maximum quantum percolation. For systems with\nperiodic boundaries, the maximum quantum percolationbetween the bound states\ncreates intermediate extended states in the bulk which is originally gapped and\ninsulating. The antidot in- duced bound states plays the same role as the\nmagnetic field inthe quantum Hall effect, both makes electrons go into\ncyclotron motions. We also draw an analogy between the quantum percolation\nphenomena in this system and that in the network models of quantum Hall effect."
    },
    {
        "anchor": "Phonon-Induced Dephasing in Quantum Dot-Cavity QED: We present a semi-analytic and asymptotically exact solution to the problem\nof phonon-induced decoherence in a quantum dot-microcavity system. Particular\nemphasis is placed on the linear polarization and optical absorption, but the\napproach presented herein may be straightforwardly adapted to address any\nelements of the exciton-cavity density matrix. At its core, the approach\ncombines Trotter's decomposition theorem with the linked cluster expansion. The\neffects of the exciton-cavity and exciton-phonon couplings are taken into\naccount on equal footing, thereby providing access to regimes of comparable\npolaron and polariton timescales. We show that the optical decoherence is\nrealized by real phonon-assisted transitions between different polariton states\nof the quantum dot-cavity system, and that the polariton line broadening is\nwell-described by Fermi's golden rule in the polariton frame. We also provide\npurely analytic approximations which accurately describe the system dynamics in\nthe limit of longer polariton timescales.",
        "positive": "An accurate tight binding model for twisted bilayer graphene describes\n  topological flat bands without geometric relaxation: A major hurdle in understanding the phase diagram of twisted bilayer graphene\n(TBLG) are the roles of lattice relaxation and electronic structure on isolated\nband flattening near magic twist angles. In this work, the authors develop an\naccurate local environment tight binding model (LETB) fit to tight binding\nparameters computed from $ab\\ initio$ density functional theory (DFT)\ncalculations across many atomic configurations. With the accurate\nparameterization, it is found that the magic angle shifts to slightly lower\nangles than often quoted, from around 1.05$^\\circ$ to around 0.99$^\\circ$, and\nthat isolated flat bands appear for rigidly rotated graphene layers, with\nenhancement of the flat bands when the layers are allowed to distort. Study of\nthe orbital localization supports the emergence of fragile topology in the\nisolated flat bands without the need for lattice relaxation."
    },
    {
        "anchor": "Second spectrum of charge carrier density fluctuations in graphene due\n  to trapping/detrapping processes: We investigate the second spectrum of charge carrier density fluctuations in\ngraphene within the McWorther model, where noise is induced by electron traps\nin the substrate. Within this simple picture, we obtain a closed-form\nexpression including both Gaussian and non-Gaussian fluctuations. We show that\na very extended distribution of switching rates of the electron traps in the\nsubstrate leads to a carrier density power spectrum with a non-trivial\nstructure on the scale of the measurement bandwidth. This explains the\nappearance of a $1/f$ component in the Gaussian part of the second spectrum,\nwhich adds up to the expected frequency-independent term. Finally, we find that\nthe non-Gaussian part of the second spectrum can become quantitatively relevant\nby approaching extremely low temperatures.",
        "positive": "Magnetoroton scattering by phonons in the fractional quantum Hall regime: Motivated by recent phonon spectroscopy experiments in the fractional quantum\nHall regime we consider processes in which thermally excited magnetoroton\nexcitations are scattered by low energy phonons. We show that such scattering\nprocesses can never give rise to dissociation of magnetorotons into unbound\ncharged quasiparticles as had been proposed previously. In addition we show\nthat scattering of magnetorotons to longer wavelengths by phonon absorption is\npossible because of the shape of the magnetoroton dispersion curve and it is\nshown that there is a characteristic cross-over temperature above which the\nrate of energy transfer to the electron gas changes from an exponential\n(activated) to a power law dependence on the effective phonon temperature."
    },
    {
        "anchor": "Coupling superconducting flux qubits at optimal point via dynamic\n  decoupling with the quantum bus: We propose a scheme with dc-control of finite bandwidth to implement\ntwo-qubit gate for superconducting flux qubits at the optimal point. We provide\na detailed non-perturbative analysis on the dynamic evolution of the qubits\ninteracting with a common quantum bus. An effective qubit-qubit coupling is\ninduced while decoupling the quantum bus with proposed pulse sequences. The\ntwo-qubit gate is insensitive to the initial state of the quantum bus and\napplicable to non-perturbative coupling regime which enables rapid two-qubit\noperation. This scheme can be scaled up to multi-qubit coupling.",
        "positive": "Graphene-based resonant-tunneling strucures: Resonant electronic transmission through graphene-based double barriers\n(wells) is studied as a function of the incident wave vector, the widths and\nheights (depths) of the barriers (wells), and the separation between them.\nResonant features in the transmission result from resonant electron states in\nthe wells or hole states in the barriers and strongly influence the ballistic\nconductance of the structures."
    },
    {
        "anchor": "Telecommunication band InAs quantum dots and dashes embedded in\n  different barrier materials: We investigate the long wavelength (1.2 to 1.55 micro-m) photoluminescence of\nhigh-density InAs quantum dots and dashes, which were grown on InP substrates.\nWe analyze the temperature dependence of the recombination and carrier\ndistribution on the alloy composition of the barrier materials, InGaAlAs, and\non the existence of a wetting layer. Carrier escape and transfer are discussed\nbased on temperature dependent photoluminescence measurements and theoretical\nconsiderations about the heterostructures' confinement energies and band\nstructure. We propose two different contributions to the thermal quenching,\nwhich can explain the observations for both the quantum dot and dash samples.\nAmong these one is a unique phenomenon for high density quantum dot/dash\nensembles which is related to significant inter-dot/dash coupling. With the\ngoal ahead to use these dots and dashes for quantum optical applications on the\nsingle-dot/dash level in the telecommunication C band as well as at elevated\ntemperatures we present first steps towards the realization of such devices.",
        "positive": "Unravelling the Spin Dynamics of Molecular Nanomagnets with\n  Four-Dimensional Inelastic Neutron Scattering: Molecular Nanomagnets have attracted the attention of the scientific\ncommunity since the rich physics behind their magnetic behaviour make them\nideal test-beds for fundamental concepts in quantum mechanics. Sophisticated\nexperiments and targeted research activities have also unveiled their potential\nfor several technological applications. Inelastic neutron scattering is a\npowerful and widely used technique to investigate the properties of these\nsystems. The new generation of spectrometers, equipped with arrays of\nposition-sensitive detectors, enable to efficiently measure the neutron\ncross-sections as a function of energy and of the three component of the\nmomentum transfer vector Q, in vast portions of the reciprocal space.\nExploiting these capabilities together with the availability of sufficiently\nlarge single-crystal samples of MNMs, it is now possible to obtain an\nunprecedented insight into the coherent spin dynamics of these molecular\nclusters. This is witnessed by several recent results, that we present in this\nreview. By using the benchmark system Cr$_8$, it has been demonstrated that the\nrichness of the four-dimensional inelastic neutrons scattering technique\nenables to extract dynamical correlation functions directly from the data. This\ntechnique has been also applied to the archetypical single-molecule magnet\nMn$_{12}$ to unambiguously characterise its Spin Hamiltonian as well as to\nportray the entanglement between molecular qubits in (Cr$_7$Ni)$_2$."
    },
    {
        "anchor": "Regularized continuum model of a Weyl semimetal for describing anomalous\n  electromagnetic response: Although the Weyl model with an unbounded linear energy spectrum\nappropriately describes low-energy electron states in a Weyl semimetal, it\ncannot capture the anomalous electromagnetic response of the chiral magnetic\neffect (CME) and anomalous Hall effect (AHE) in a straightforward manner. Here,\nwe propose a regularized continuum model by modifying the Weyl model and show\nthat it properly describes the CME and AHE in a unified manner. It turns out\nthat the absence of the CME at equilibrium is guaranteed by a basic nature of\nthe Berry curvature. We also show that the original Weyl model can properly\ndescribe the CME if an energy cutoff procedure is appropriately applied,\nalthough it fails to describe the AHE in its present form.",
        "positive": "Simultaneous individual and dipolar collective properties in binary\n  assemblies of magnetic nanoparticles: Applications based on aggregates of magnetic nanoparticles are becoming\nincreasingly widespread, ranging from hyperthermia to magnetic recording.\nHowever, although some uses require a collective behavior, other need a more\nindividual-like response, the conditions leading to either of these behaviors\nare still poorly understood. Here we use nanoscale-uniform binary random dense\nmixtures with different proportions of oxide magnetic nanoparticles with\nlow$/$high anisotropy as a valuable tool to explore the crossover from\nindividual to collective behavior. Two different anisotropy scenarios have been\nstudied in two series of binary compacts: M1, comprising maghemite\n($\\gamma$-Fe$_2$O$_3$) nanoparticles of different sizes (9.0 nm $/$ 11.5 nm)\nwith barely a factor of 2 between their anisotropy energies and M2, mixing\nequally-sized pure maghemite (low-anisotropy) and Co-doped maghemite\n(high-anisotropy) nanoparticles with a large difference in anisotropy energy\n(ratio $>$ 8). Interestingly, while the M1 series exhibits collective behavior\ntypical of strongly-coupled dipolar systems, the M2 series presents a more\ncomplex scenario where different magnetic properties resemble either\n\"individual-like\" or \"collective\", crucially emphasizing that the collective\ncharacter must be ascribed to specific properties and not to the system as a\nwhole. The strong differences between the two series, offer new insight\n(systematically ratified by simulations) into the subtle interplay between\ndipolar interactions, local anisotropy and sample heterogeneity, to determine\nthe behavior of dense assemblies of magnetic nanoparticles."
    },
    {
        "anchor": "Long- to short-junction crossover and field-reentrant critical current\n  in Al/Ag-nanowires/Al Josephson junctions: We have probed the superconducting proximity effect through long high-quality\nmonocrystalline Ag nanowires, by realizing Josephson junctions of different\nlengths, with different superconducting materials. Thanks to the high number of\njunctions probed, both the contact resistance and electron diffusion constant\ncould be determined, enabling a comparison of the measured critical current to\ntheoretical expectation, over the entire regime from short to long diffusive\njunction. Although the length dependence of the critical current is as\nexpected, the amplitude of the $R_{N}I_c$ product is smaller than predicted by\ntheory. We also address the magnetic field dependence of the critical current.\nThe quasi-gaussian decay of the critical current with field expected of a long\nnarrow junction is observed for all superconducting contacts we used except for\naluminum. We present the striking non-monotonous effect of field on the\ncritical current of junctions with aluminum contacts, and analyze it in terms\nof improved quasiparticle thermalization by a magnetic field.",
        "positive": "Observation of Spin Relaxation Anisotropy in Semiconductor Quantum Wells: Spin relaxation of two-dimensional electrons in asymmetrical (001) AlGaAs\nquantum wells are measured by means of Hanle effect. Three different spin\nrelaxation times for spins oriented along [110], [1-10] and [001]\ncrystallographic directions are extracted demonstrating anisotropy of\nD'yakonov-Perel' spin relaxation mechanism. The relative strengths of Rashba\nand Dresselhaus terms describing the spin-orbit coupling in semiconductor\nquantum well structures. It is shown that the Rashba spin-orbit splitting is\nabout four times stronger than the Dresselhaus splitting in the studied\nstructure."
    },
    {
        "anchor": "Velocity shift of surface acoustic waves due to interaction with\n  composite fermions in a modulated structure: We study the effect of a periodic density modulation on surface acoustic wave\n(SAW) propagation along a 2D electron gas near Landau level filling $\\nu=1/2$.\nWithin the composite fermion theory, the problem is described in terms of\nfermions subject to a spatially modulated magnetic field and scattered by a\nrandom magnetic field. We find that a few percent modulation induces a large\npeak in the SAW velocity shift, as has been observed recently by Willett et al.\nAs further support of this theory we find the dc resistivity to be in good\nagreement with recent data of Smet et al.",
        "positive": "Fast spin-orbit qubit in an indium antimonide nanowire: Due to the strong spin-orbit interaction in indium antimonide, orbital motion\nand spin are no longer separated. This enables fast manipulation of qubit\nstates by means of microwave electric fields. We report Rabi oscillation\nfrequencies exceeding 100 MHz for spin-orbit qubits in InSb nanowires.\nIndividual qubits can be selectively addressed due to intrinsic dierences in\ntheir g-factors. Based on Ramsey fringe measurements, we extract a coherence\ntime T_2* = 8 +/- 1 ns at a driving frequency of 18.65 GHz. Applying a Hahn\necho sequence extends this coherence time to 35 ns."
    },
    {
        "anchor": "The magnetic structure factor of correlated moments in small-angle\n  neutron scattering: The interplay between structural and magnetic properties of nanostructured\nmagnetic materials allows to realize unconventional magnetic effects, which\nresults in a demand for experimental techniques to determine the magnetization\nprofile with nanoscale resolution. Magnetic small-angle neutron scattering\n(SANS) probes both the chemical and magnetic nanostructure and is thus a\npowerful technique e.g. for the characterization of magnetic nanoparticles.\nHere, we show that the conventionally used particle-matrix approach to describe\nSANS of magnetic particle assemblies, however, leads to a flawed\ninterpretation. As remedy, we provide general expressions for the\nfield-dependent 2D magnetic SANS cross-section of correlated moments. It is\nshown that for structurally disordered ensembles the magnetic structure factor\nis in general, and contrary to common assumptions, (i) anisotropic also in zero\nfield, and (ii) that even in saturation the magnetic structure factor deviates\nfrom the nuclear one. These theoretical predictions explain qualitatively the\nintriguing experimental, polarized SANS data of an ensemble of dipolar-coupled\niron oxide nanoparticles.",
        "positive": "Long Spin Coherence Times of Nitrogen Vacancy Centres in Milled\n  Nanodiamonds: Nanodiamonds containing negatively charged nitrogen vacancy centres\n(${\\text{NV}}^{-}$) have applications as localized sensors in biological\nmaterial and have been proposed as a platform to probe the macroscopic limits\nof spatial superposition and the quantum nature of gravity. A key requirement\nfor these applications is to obtain nanodiamonds containing ${\\text{NV}}^{-}$\nwith long spin coherence times. Using milling to fabricate nanodiamonds\nprocesses the full 3D volume of the bulk material at once, unlike etching, but\nhas, up to now, limited ${\\text{NV}}^{-}$ spin coherence times. Here, we use\nnatural isotopic abundance nanodiamonds produced by\n${\\text{Si}}_{3}{\\text{N}}_{4}$ ball milling of bulk diamond grown by chemical\nvapour deposition with an average single substitutional nitrogen concentration\nof $121 ~\\text{ppb}$. We show that the electron spin coherence times of\n${\\text{NV}}^{-}$ centres in these nanodiamonds can exceed $400 ~\\mu\\text{s}$\nat room temperature with dynamical decoupling. Scanning electron microscopy\nprovides images of the specific nanodiamonds containing ${\\text{NV}}^{-}$ for\nwhich a spin coherence time was measured."
    },
    {
        "anchor": "Snapshots of non-equilibrium Dirac carrier distributions in graphene: The optical properties of graphene are made unique by the linear band\nstructure and the vanishing density of states at the Dirac point. It has been\nproposed that even in the absence of a semiconducting bandgap, a relaxation\nbottleneck at the Dirac point may allow for population inversion and lasing at\narbitrarily long wavelengths. Furthermore, efficient carrier multiplication by\nimpact ionization has been discussed in the context of light harvesting\napplications. However, all these effects are difficult to test quantitatively\nby measuring the transient optical properties alone, as these only indirectly\nreflect the energy and momentum dependent carrier distributions. Here, we use\ntime- and angle-resolved photoemission spectroscopy with femtosecond extreme\nultra-violet (EUV) pulses at 31.5 eV photon energy to directly probe the\nnon-equilibrium response of Dirac electrons near the K-point of the Brillouin\nzone. In lightly hole-doped epitaxial graphene samples, we explore excitation\nin the mid- and near-infrared, both below and above the minimum photon energy\nfor direct interband transitions. While excitation in the mid-infrared results\nonly in heating of the equilibrium carrier distribution, interband excitations\ngive rise to population inversion, suggesting that terahertz lasing may be\npossible. However, in neither excitation regime do we find indication for\ncarrier multiplication, questioning the applicability of graphene for light\nharvesting. Time-resolved photoemission spectroscopy in the EUV emerges as the\ntechnique of choice to assess the suitability of new materials for\noptoelectronics, providing quantitatively accurate measurements of\nnon-equilibrium carriers at all energies and wavevectors.",
        "positive": "Topological frequency conversion in strongly driven quantum systems: When a physical system is subjected to a strong external multi-frequency\ndrive, its dynamics can be conveniently represented in the multi-dimensional\nFloquet lattice. The number of the Floquet lattice dimensions equals the number\nof {\\em irrationally}-related drive frequencies, and the evolution occurs in\nresponse to a built-in effective \"electric\" field, whose components are\nproportional to the corresponding drive frequencies. The mapping allows to\nengineer and study temporal analogs of many real-space phenomena. Here we focus\non the specific example of a two-level system under two-frequency drive that\ninduces topologically nontrivial band structure in the 2D Floquet space. The\nobservable consequence of such construction is quantized pumping of energy\nbetween the sources with frequencies $\\omega_1$ and $\\omega_2$. When the system\nis initialized into a Floquet band with the Chern number $C$, the pumping\noccurs at the rate $P_{12} = -P_{21}= (C/2\\pi)\\hbar \\omega_1\\omega_2$, an exact\ncounterpart of the transverse current in a conventional topological insulator."
    },
    {
        "anchor": "Tunable spin-polarized edge currents in proximitized transition metal\n  dichalcogenides: We explore proximity-induced ferromagnetism on transition metal\ndichalcogenide (TMD), focusing on molybdenum ditelluride (MoTe$_{2}$) ribbons\nwith zigzag edges, deposited on ferromagnetic europium oxide (EuO). A\nthree-orbital tight-binding model incorporates the exchange and Rashba fields\ninduced by proximity to the EuO substrate. For in-gap Fermi levels, electronic\nmodes in the nanoribbon are strongly spin-polarized and localized along the\nedges, acting as one-dimensional (1D) conducting channels with tunable\nspin-polarized currents. Hybrid structures such as the MoTe$_{2}$/EuO\nconfiguration can serve as building blocks for spintronic devices, and provide\nversatile platforms to further understand proximity effects in diverse\nmaterials systems.",
        "positive": "Kovacs memory effect with an optically levitated nanoparticle: The understanding of the dynamics of nonequilibrium cooling and heating\nprocesses at the nanoscale is still an open problem. These processes can follow\nsurprising relaxation paths due to, e.g., memory effects, which significantly\nalter the expected equilibration routes. The Kovacs effect can take place when\na thermalization process is suddenly interrupted by a change of the bath\ntemperature, leading to a non-monotonic dependence of the energy of the system.\nHere, we demonstrate that the Kovacs effect can be observed in the\nthermalization of the center of mass motion of a levitated nanoparticle. The\ntemperature is controlled during the experiment through an external source of\nwhite gaussian noise. We describe our experiments in terms of the dynamics of a\nBrownian particle in a harmonic trap without any fitting parameter, suggesting\nthat the Kovacs effect canappear in a large variety of systems."
    },
    {
        "anchor": "Effect of Laughlin correlations on crystalline mean field solutions of\n  the 2DEG in FQHE regime: The energy per particle of many body wavefunctions that mix Laughlin liquid\nwith crystalline correlations for periodic samples in the Haldane-Rezayi\nconfiguration is numerically evaluated for periodic samples. The Monte Carlo\nalgorithm is employed and the wave functions are constructed in such a way that\nhave the same zeroes as the periodic Laughlin states. Results with up to 16\nparticles show that these trial wavefunctions have lower energy than the\nperiodic Laughlin states for finite samples even at $\\nu=1/3$. Preliminary\nresults for 36 particles suggest that this tendency could reach the\nthermodynamic limit. These results get relevance in view of the very recent\nexperimental measures that indicate the presence of periodic structures in the\n2DEG for extremely small temperatures and clean samples, inclusive at main FQHE\nfilling fractions $\\nu=1/3,2/3 $.",
        "positive": "Observation of mixed anisotropy in the critical susceptibility of an\n  ultrathin magnetic film: Measurements of the magnetic susceptibility of Fe/W(110) films with thickness\nin the range of 1.6 to 2.4 ML Fe, show that in addition to the large response\nalong the easy axis associated with the Curie transition, there is a much\nsmaller, paramagnetic hard axis response that is not consistent with the 2D\nanisotropic Heisenberg model used to describe homogeneous in-plane ferromagnets\nwith uniaxial anisotropy. The shape, amplitude, and peak temperature of the\nhard axis susceptibility, as well as its dependence upon layer completion close\nto 2.0 ML, indicate that inhomogeneities in the films create a system of mixed\nanisotropy. A likely candidate for inhomogeneities that are magnetically\nrelevant in the critical region are the closed lines of step edges associated\nwith the incomplete layers. According to the Harris criterion, the existence of\nmagnetically relevant inhomogeneities may alter the critical properties of the\nfilms from those of a 2D Ising model. Experiments in the recent literature are\ndiscussed in this context."
    },
    {
        "anchor": "Ferroelectric-Gated Terahertz Plasmonics on Graphene: Inspired by recent advancement of low-power ferroelectic-gated memories and\ntransistors, we propose a design of ferroelectic-gated nanoplasmonic devices\nbased on graphene sheets clamped in ferroelectric crystals. We show that the\ntwo-dimensional plasmons in graphene strongly couple with the phonon-polaritons\nin ferroelectrics at terahertz frequencies, leading to characteristic modal\nwavelength of the order of 100--200 nm at only 3--4 THz. By patterning the\nferroelectrics into different domains, one can produce compact on-chip\nplasmonic waveguides, which exhibit negligible crosstalk even at 50 nm\nseparation distance. Harnessing the memory effect of ferroelectrics, low-power\nelectro-optical switching can be achieved on these plasmonic waveguides.",
        "positive": "Hamiltonian Description of Composite Fermions: Calculation of Gaps: We analytically calculate gaps for the 1/3, 2/5, and 3/7 polarized and\npartially polarized Fractional Quantum Hall states based on the Hamiltonian\nChern-Simons theory we have developed. For a class of potentials that are soft\nat high momenta (due to the finite thickness of the sample) we find good\nagreement with numerical and experimental results."
    },
    {
        "anchor": "Field emission from self-catalyzed GaAs nanowires: We report observation of field emission from self-catalyzed GaAs nanowires\ngrown on Si (111). The measurements are realized inside a scanning electron\nmicroscope chamber with nano-controlled tungsten tip functioning as anode.\nExperimental data are analyzed in the framework of Fowler-Nordheim theory. We\ndemonstrate stable current up to 10$^{-7}$ A emitted from the tip of single\nnanowire, with field enhancement factor $\\beta$ up to 112 at anode-cathode\ndistance d=350 nm. A linear dependence of $\\beta$ on the anode-cathode distance\nis experimentally found. We also show that the presence of a Ga catalyst\ndroplet suppresses the emission of current from the nanowire tip. This allows\ndetection of field emission from the nanowire sidewalls, which occurs with\nreduced field enhancement factor and stability. This study further extends the\nGaAs technology to vacuum electronics applications.",
        "positive": "Electronic Transmission Through Metallic Nanowires: Generalized\n  Scattering Matrix Approach: An easy to implement and powerful method for the solution of 3D scattering\nproblems that can be well described by Helmholtz equation is presented. The\nmatrix algebra used provides excellent stability versus the number of junctions\nas well as great computational speed. The matrix truncation method yields an\neasy single-parameter convergence procedure. Subsequently, some aspects of the\nelectronic transport through metal nanowires are studied by the use of\nLandauer's scattering approach to the conductance. We predict the existence of\ncurrent vortex-rings patterns due to sharp enough narrow-wide connections in\natomic size point contacts. Longitudinal resonances between scattering centers\nprovide a simple physical picture for the understanding of negative\ndifferential resistance in ideal monoatomic contacts. Relatively long nanowires\nwith high geometrical perfection -like those recently observed by Transmission\nElectron Microscopy- are modelled exhibiting resonant tunnelling and total\nreflection at given incident energy intervals."
    },
    {
        "anchor": "Two- and three-electron bubbles in\n  Al$_{x}$Ga$_{1-x}$As/Al$_{0.24}$Ga$_{0.76}$As quantum wells: We report on transport signatures of eight distinct bubble phases in the\n$N=3$ Landau level of a Al$_{x}$Ga$_{1-x}$As/Al$_{0.24}$Ga$_{0.76}$As quantum\nwell with $x = 0.0015$. These phases occur near partial filling factors\n$\\nu^\\star \\approx 0.2\\,(0.8)$ and $\\nu^\\star \\approx 0.3\\,(0.7)$ and have $M =\n2$ and $M = 3$ electrons (holes) per bubble, respectively. We speculate that a\nsmall amount of alloy disorder in our sample helps to distinguish these broken\nsymmetry states in low-temperature transport measurements.",
        "positive": "Orbital magnetic ratchet effect: Magnetic ratchets -- two-dimensional systems with superimposed\nnon-centrosymmetric ferromagnetic gratings -- are considered theoretically. It\nis demonstrated that excitation by radiation results in a directed motion of\ntwo-dimensional carriers due to pure orbital effect of the periodic magnetic\nfield. Magnetic ratchets based on various two-dimensional systems like\ntopological insulators, graphene and semiconductor heterostructures are\ninvestigated. The mechanisms of the electric current generation caused by both\nradiation-induced heating of carriers and by acceleration in the radiation\nelectric field in the presence of space-oscillating Lorentz force are studied\nin detail. The electric currents sensitive to the linear polarization plane\norientation as well as to the radiation helicity are calculated. It is\ndemonstrated that the frequency dependence of the magnetic ratchet currents is\ndetermined by the dominant elastic scattering mechanism of two-dimensional\ncarriers and differs for the systems with linear and parabolic energy\ndispersions."
    },
    {
        "anchor": "Phonon transport in large scale carbon-based disordered materials:\n  Implementation of an efficient order-N and real-space Kubo methodology: We have developed an efficient order-N real-space Kubo approach for the\ncalculation of the phonon conductivity which outperforms state-of-the-art\nalternative implementations based on the Green's function formalism. The method\ntreats efficiently the time-dependent propagation of phonon wave packets in\nreal space, and this dynamics is related to the calculation of the thermal\nconductance. Without loss of generality, we validate the accuracy of the method\nby comparing the calculated phonon mean free paths in disordered carbon\nnanotubes (isotope impurities) with other approaches, and further illustrate\nits upscalability by exploring the thermal conductance features in large width\nedge-disordered graphene nanoribbons (up to ~20 nm), which is out of the reach\nof more conventional techniques. We show that edge-disorder is the most\nimportant scattering mechanism for phonons in graphene nanoribbons with\nrealistic sizes and thermal conductance can be reduced by a factor of ~10.",
        "positive": "Abelian and Non-abelian Hall Liquids and Charge Density Wave: Quantum\n  Number Fractionalization in One and Two Dimensions: Previously we have demonstrated that, on a torus, the abelian quantum hall\nliquid is adiabatically connected to a charge density wave as the smaller\ndimension of the torus is varied. In this work we extend this result to the\nnon-abelian bosonic Hall state. The outcome of these works is the realization\nthat the paradigms of quantum number fractionalization in one dimension\n(polyacetylene) and two dimensions (fractional quantum Hall effect) are in fact\nequivalent."
    },
    {
        "anchor": "Mesoscopic threshold detectors: Telegraphing the size of a fluctuation: We propose a two-terminal method to measure shot noise in mesoscopic systems\nbased on an instability in the current-voltage characteristic of an on-chip\ndetector. The microscopic noise drives the instability, which leads to random\nswitching of the current between two values, the telegraph process. In the\nGaussian regime, the shot noise power driving the instability may be extracted\nfrom the I-V curve, with the noise power as a fitting parameter. In the\nthreshold regime, the extreme value statistics of the mesoscopic conductor can\nbe extracted from the switching rates, which reorganize the complete\ninformation about the current statistics in an indirect way, \"telegraphing\" the\nsize of a fluctuation. We propose the use of a quantum double dot as a\nmesoscopic threshold detector.",
        "positive": "Size Effects on Mechanical Properties of Micro/Nano Structures: Experiments on Micro- and Nano-mechanical systems (M/NEMS) have shown that\ntheir behavior upon bending loads departs in many cases from the classical\npredictions using Euler-Bernoulli theory and Hooke law. This anomalous response\nhas usually been seen as a dependence of the material properties with the size\nof the structure, in particular thickness. A theoretical model that allows for\nquantitative understanding and prediction of this size effect is important for\nthe design of M/NEMS. In this paper, we summarize and analyze the five theories\nthat can be found in the literature: Grain Boundary Theory (GBT), Surface\nStress Theory (SST), Residual Stress Theory (RST), Couple Stress Theory (CST)\nand Surface Elasticity Theory (SET). By comparing these theories with\nexperimental data we propose a simplified model combination of CST and SET that\nproperly fits all considered cases, therefore delivering a simple (two\nparameters) model that can be used to predict the mechanical properties at the\nnanoscale."
    },
    {
        "anchor": "Spin-dependent inertial force and spin current in accelerating systems: The spin-dependent inertial force in an accelerating system under the\npresence of electromagnetic fields is derived from the generally covariant\nDirac equation. Spin currents are evaluated by the force up to the lowest order\nof the spin-orbit coupling in both ballistic and diffusive regimes. We give an\ninterpretation of the inertial effect of linear acceleration on an electron as\nan effective electric field and show that mechanical vibration in a high\nfrequency resonator can create a spin current via the spin-orbit interaction\naugmented by the linear acceleration.",
        "positive": "Topology and Observables of the Non-Hermitian Chern Insulator: Topology plays a central role in nearly all disciplines of physics, yet its\napplications have so far been restricted to closed, lossless systems in\nthermodynamic equilibrium. Given that many physical systems are open and may\ninclude gain and loss mechanisms, there is an eminent need to reexamine\ntopology within the context of non-Hermitian theories that describe open, lossy\nsystems. The recent generalization of the Chern number to non-Hermitian\nHamiltonians initiated this reexamination; however, there is so far no\nestablished connection between a non-Hermitian topological invariant and the\nquantization of an observable. In this work, we show that no such relationship\nexists between the Chern number of non-Hermitian bands and the quantization of\nthe Hall conductivity. Using field theoretical techniques, we calculate the\nlongitudinal and Hall conductivities of a non-Hermitian Hamiltonian with a\nfinite Chern number to explicitly demonstrate the physics of a non-quantized\nHall conductivity despite an invariable Chern number. These results demonstrate\nthat the Chern number does not provide a physically meaningful classification\nof non-Hermitian Hamiltonians."
    },
    {
        "anchor": "Spin effects in ferromagnetic single-electron transistors: Electron tunneling in ferromagnetic single-electron transistors is considered\ntheoretically in the sequential tunneling regime. A new formalism is developed,\nwhich operates in a two-dimensional space of states, instead of one-dimensiona\nspace used in the spinless case. It is shown that spin fluctuations can be\nsignificantly larger than the charge fluctuations. The influence of discrete\nenergy spectrum of a small central electrode on tunneling current, charge and\nspin accumulation, charge and spin fluctuations, and on tunnel\nmagnetoresistance is analyzed in details. Two different scales are found in the\nbias dependence of the basic transport characteristics; the shorter one\noriginates from the discrete energy spectrum and the longer one from discrete\ncharging of the central electrode. The features due to discrete spectrum and\ndiscrete charging disappear at high temperatures.",
        "positive": "Shot-Noise-Limited Operation of a Fast Quantum-Point-Contact Charge\n  Sensor: We have operated a quantum point contact (QPC) charge detector in a radio\nfrequency (RF) mode that allows fast charge detection in a bandwidth of tens of\nmegahertz. We find that the charge sensitivity of the RF-QPC is limited not by\nthe noise of a secondary amplifier, but by non-equilibrium noise f the QPC\nitself. We have performed frequency-resolved measurements of the noise within a\n10 MHz bandwidth around our carrier wave. When averaged over our bandwidth, we\nfind that the noise is in good agreement with the theory of photon-assisted\nshot noise. Our measurements also reveal strong frequency dependence of the\nnoise, asymmetry with respect to the carrier wave, the appearance of sharp\nlocal maxima that are correlated with mechanical degrees of freedom in the\nsample, and noise suppression indicative of many-body physics near the 0.7\nstructure."
    },
    {
        "anchor": "Nutation spin waves in ferromagnets: Magnetization dynamics and spin waves in ferromagnets are investigated using\nthe inertial Landau-Lifshitz-Gilbert equation. Taking inertial magnetization\ndynamics into account, dispersion relations describing the propagation of\nnutation spin waves in an arbitrary direction relative to the applied magnetic\nfield are derived via Maxwell's equations. It is found that the inertia of\nmagnetization causes the hybridization of electromagnetic waves and nutation\nspin waves in ferromagnets, hybrid nutation spin waves emerge, and the redshift\nof frequencies of precession spin waves is initiated, which transforms to\nprecession-nutation spin waves. These effects depend sharply on the direction\nof wave propagation relative to the applied magnetic field. Moreover, the waves\npropagating parallel to the applied field are circularly polarized, while the\nwaves propagating perpendicular to that field are elliptically polarized. The\ncharacteristics of these spin nutation waves are also analyzed.",
        "positive": "Electric-Field Control of the Interlayer Exchange Coupling for\n  Magnetization Switching: We propose an electric-field-controlled mechanism for magnetization switching\nassisted solely by the interlayer-exchange coupling (IEC) between the fixed and\nthe free magnets, which are separated by two oxide barriers sandwiching a\nspacer material known for exhibiting large IEC. The basic idea relies on the\nformation of a quantum-well (QW) within the spacer material and controlling the\ntransmission coefficient across the structure with an electric-field via the\nresonant tunneling phenomena. Using non-equilibrium Green's function (NEGF)\nmethod, we show that the structure can exhibit a bias-dependent oscillatory IEC\nthat can switch the free magnet to have either a parallel or an antiparallel\nconfiguration with respect to the fixed magnet, depending on the sign of the\nIEC. Such bi-directional switching can be achieved with the same voltage\npolarity but different magnitudes. With proper choice of the spacer material,\nthe current in the structure can be significantly reduced. Due to the\nconservative nature of the exerted torque by the IEC, the switching threshold\nof the proposed mechanism is decoupled from the switching speed, while the\nconventional spin-torque devices exhibit a trade-off due to the\nnon-conservative nature of the exerted torque."
    },
    {
        "anchor": "Tunable two-dimensional electron gas at the surface of thermoelectric\n  material In$_4$Se$_3$: We report the discovery of two-dimensional electron gas (2DEG) at the surface\nof thermoelectric material In$_4$Se$_3$ by angle-resolved photoemission\nspectroscopy. The observed 2DEG exhibits a nearly isotropic band dispersion\nwith a considerably small effective mass of m* = 0.16 m_0, and its carrier\ndensity shows a significant temperature dependence, leading to unconventional\nmetal-semiconductor transition at the surface. The observed wide-range thermal\ntunability of 2DEG in In$_4$Se$_3$ gives rise to additional degrees of freedom\nto better control the surface carriers of semiconductors.",
        "positive": "Multiple crossing of Landau levels of two-dimensional fermions in double\n  HgTe quantum wells: The double quantum well systems consisting of two HgTe layers separated by a\ntunnel-transparent barrier are expected to manifest a variety of phase states\nincluding two-dimensional gapless semimetal and two-dimensional topological\ninsulator. The presence of several subbands in such systems leads to a rich\nfilling factor diagram in the quantum Hall regime. We have performed\nmagnetotransport measurements of the HgTe-based double quantum wells in both\ngapless and gapped state and observed numerous crossings between the Landau\nlevels belonging to different subbands. We analyze the Landau level crossing\npatterns and compare them to the results of theoretical calculations."
    },
    {
        "anchor": "Gigantic intrinsic orbital Hall effects in weakly spin-orbit coupled\n  metals: A recent paper [Go $\\textit{et al}$., Phys. Rev. Lett. $\\textbf{121}$, 086602\n(2018)] proposed that the intrinsic orbital Hall effect (OHE) can emerge from\nmomentum-space orbital texture in centrosymmetric materials. In searching for\nreal materials with strong OHE, we investigate the intrinsic OHE in metals with\nsmall spin-orbit coupling (SOC) in face-centered cubic and body-centered cubic\nstructures (Li, Al, V, Cr, Mn, Ni, and Cu). We find that orbital Hall\nconductivities (OHCs) in these materials are gigantic $\\sim 10^3-10^4\\\n(\\hbar/e)(\\Omega\\cdot\\mathrm{cm})^{-1}$, which are comparable or larger than\nspin Hall conductivity (SHC) of Pt. Although SHCs in these materials are\nsmaller than OHCs due to small SOC, we found that SHCs are still sizable and\nthe spin Hall angles may be of the order of 0.1. We discuss implications on\nrecent spin-charge interconversion experiments on materials having small SOC.",
        "positive": "Spectral asymmetry induces a re-entrant quantum Hall effect in a\n  topological insulator: The band inversion of topological materials in three spatial dimensions is\nintimately connected to the parity anomaly of two-dimensional massless Dirac\nfermions. At finite magnetic fields, the parity anomaly reveals itself as a\nnon-zero spectral asymmetry, i.e., a non-zero difference between the number of\nconduction and valence band Landau levels, due to the unpaired zero Landau\nlevel. Here, we realize this two-dimensional Dirac physics at a single surface\nof the three-dimensional topological insulator (Hg,Mn)Te. We observe an\nunconventional re-entrant quantum Hall effect that can be directly related to\nthe occurrence of spectral asymmetry in a single topological surface state. The\neffect should be observable in any topological insulator where the transport is\ndominated by a single Dirac surface state."
    },
    {
        "anchor": "Nonequilibrium spin noise spectroscopy: Spin Noise Spectroscopy (SNS) is an experimental approach to obtain\ncorrelators of mesoscopic spin fluctuations in time by purely optical means. We\nexplore the information that this technique can provide when it is applied to a\nweakly non-equilibrium regime when an electric current is driven through a\nsample by an electric field. We find that the noise power spectrum of\nconducting electrons experiences a shift, which is proportional to the strength\nof the spin-orbit coupling for electrons moving along the electric field\ndirection. We propose applications of this effect to measurements of spin orbit\ncoupling anisotropy and separation of spin noise of conducting and localized\nelectrons.",
        "positive": "Excitons and optical spectra of phosphorene nanoribbons: On the basis of many-body {\\it ab-initio} calculations, using single-shot\nG$_0$W$_0$ method and Bethe-Salpeter equation, we study phosphorene nanoribbons\n(PNRs) in the two typical zigzag and armchair directions. The electronic\nstructure, optical absorption, electron-hole (exciton) binding energy, exciton\nexchange splitting, and exciton wave functions are calculated for different\nsize of PNRs. The typically strong splitting between singlet and triplet\nexcitonic states make PNRs favorable systems for application in optoelectronic.\nQuantum confinement occurs in both kinds of PNRs, and it is stronger in the\nzPNRs, as behave like quasi-zero-dimensional systems. Scaling laws are\ninvestigated for the size-dependent behaviors of PNRs. The first bright\nexcitonic state in PNRs is explored in detail."
    },
    {
        "anchor": "Fractional Quantum Hall States in Fast Rotating Bose Gases: We use a Chern Simons Landau-Ginzburg (CSLG) framework related to hierarchies\nof composite bosons to describe 2D harmonically trapped fast rotating Bose\ngases in Fractional Quantum Hall Effect (FQHE) states. The predicted values for\n$\\nu$ (ratio of particle to vortex numbers) are $\\nu$$=$${{p}\\over{q}}$ ($p$,\n$q$ are any integers) with even product $pq$, including numerically favored\nvalues previously found and predicting a richer set of values. We show that\nthose values can be understood from a bosonic analog of the law of the\ncorresponding states relevant to the electronic FQHE. A tentative global phase\ndiagram for the bosonic system for $\\nu$$<$1 is also proposed.",
        "positive": "Imaging antiferromagnetic antiphase domain boundaries using magnetic\n  Bragg diffraction phase contrast: Manipulating magnetic domains is essential for many technological\napplications. Recent breakthroughs in Antiferromagnetic Spintronics brought up\nnovel concepts for electronic device development. Imaging antiferromagnetic\ndomains is of key importance to this field. Unfortunately, some of the basic\ndomain types, such as antiphase domains, cannot be imaged by conventional\ntechniques. Herein, we present a new domain projection imaging technique based\non the localization of domain boundaries by resonant magnetic diffraction of\ncoherent x rays. Contrast arises from reduction of the scattered intensity at\nthe domain boundaries due to destructive interference effects. We demonstrate\nthis approach by imaging antiphase domains in a collinear antiferromagnet\nFe2Mo3O8, and observe evidence of domain wall interaction with a structural\ndefect. This technique does not involve any numerical algorithms. It is fast,\nsensitive, produces large-scale images in a single-exposure measurement, and is\napplicable to a variety of magnetic domain types."
    },
    {
        "anchor": "Bulk-edge correspondence, spectral flow and Atiyah-Patodi-Singer theorem\n  for the Z2-invariant in topological insulators: We study the bulk-edge correspondence in topological insulators by taking\nFu-Kane spin pumping model as an example. We show that the Kane-Mele invariant\nin this model is Z2 invariant modulo the spectral flow of a single-parameter\nfamily of 1+1-dimensional Dirac operators with a global boundary condition\ninduced by the Kramers degeneracy of the system. This spectral flow is defined\nas an integer which counts the difference between the number of eigenvalues of\nthe Dirac operator family that flow from negative to non-negative and the\nnumber of eigenvalues that flow from non-negative to negative. Since the bulk\nstates of the insulator are completely gapped and the ground state is assumed\nbeing no more degenerate except the Kramers, they do not contribute to the\nspectral flow and only edge states contribute to. The parity of the number of\nthe Kramers pairs of gapless edge states is exactly the same as that of the\nspectral flow. This reveals the origin of the edge-bulk correspondence, i.e.,\nwhy the edge states can be used to characterize the topological insulators.\nFurthermore, the spectral flow is related to the reduced eta-invariant and thus\ncounts both the discrete ground state degeneracy and the continuous gapless\nexcitations, which distinguishes the topological insulator from the\nconventional band insulator even if the edge states open a gap due to a strong\ninteraction between edge modes. We emphasize that these results are also valid\neven for a weak disordered and/or weak interacting system. The higher spectral\nflow to categorize the higher-dimensional topological insulators are expected.",
        "positive": "Giant Quantum Freezing of Tunnel Junctions mediated by Environments: We investigate the quantum heat exchange between a nanojunction and a\nmany-body or electromagnetic environment far from equilibrium. It is shown that\nthe two-temperature energy emission-absorption mechanism gives rise to a giant\nheat flow between the junction and the environment. We obtain analytical\nresults for the heat flow in an idealized high impedance environment and\nperform numerical calculations for the general case of interacting electrons\nand discuss the giant freezing and heating effects in the junction under\ntypical experimental conditions."
    },
    {
        "anchor": "Steering Zitterbewegung in driven Dirac systems -- from persistent modes\n  to echoes: Although zitterbewegung -- the jittery motion of relativistic particles -- is\nknown since 1930 and was predicted in solid state systems long ago, it has been\ndirectly measured so far only in so-called quantum simulators, i.e. quantum\nsystems under strong control such as trapped ions and Bose-Einstein\ncondensates. A reason for the lack of further experimental evidence is the\ntransient nature of wave packet zitterbewegung. Here we study how the jittery\nmotion can be manipulated in Dirac systems via time-dependent potentials, with\nthe goal of slowing down/preventing its decay, or of generating its revival.\nFor the harmonic driving of a mass term, we find persistent zitterbewegung\nmodes in pristine, i.e. scattering free, systems. Furthermore, an effective\ntime-reversal protocol -- the \"Dirac quantum time mirror\" -- is shown to\nretrieve zitterbewegung through echoes.",
        "positive": "Effective field theory of magnon: Dynamics in chiral magnets and\n  Schwinger mechanism: We develop the effective field theoretical descriptions of spin systems in\nthe presence of symmetry-breaking effects: the magnetic field, single-ion\nanisotropy, and Dzyaloshinskii-Moriya interaction. Starting from the lattice\ndescription of spin systems, we show that the symmetry-breaking terms\ncorresponding to the above effects can be incorporated into the effective field\ntheory as a combination of a background (or spurious) $\\SO(3)$ gauge field and\na scalar field in the symmetric tensor representation, which are eventually\nfixed at their physical values. We use the effective field theory to\ninvestigate mode spectra of inhomogeneous ground states, with focusing on\none-dimensionally inhomogeneous states, such as helical and spiral states.\nAlthough the helical and spiral ground states share a common feature of\nsupporting the gapless Nambu-Goldstone modes associated with the translational\nsymmetry breaking, they have qualitatively different dispersion relations:\nisotropic in the helical phase while anisotropic in the spiral phase. We also\ndiscuss the magnon production induced by an inhomogeneous magnetic field, and\nfind a formula akin to the Schwinger formula. Our formula for the magnon\nproduction gives a finite rate for antiferromagnets, and a vanishing rate for\nferromagnets, whereas that for ferrimagnets interpolates between the two cases."
    },
    {
        "anchor": "Detection of current induced spin polarization in epitaxial Bi$_2$Te$_3$\n  thin film: We electrically detect charge current induced spin polarization on the\nsurface of molecular beam epitaxy grown Bi$_2$Te$_3$ thin film in a\ntwo-terminal device with a ferromagnetic MgO/Fe and a nonmagnetic Ti/Au\ncontact. The two-point resistance, measured in an applied magnetic field, shows\na hysteresis tracking the magnetization of the Fe. A theoretical estimate is\nobtained for the change in resistance on reversing the magnetization direction\nof Fe from coupled spin-charge transport equations based on quantum kinetic\ntheory. The order of magnitude and the sign of the hysteresis is consistent\nwith spin-polarized surface state of Bi$_2$Te$_3$.",
        "positive": "On the environmental decoherence and spin interference in mesoscopic\n  loop structures: Mechanisms of 'environmental decoherence' such as surface scattering,\nElliot-Yafet process and precession mechanisms, as well as their influence on\nthe spin phase relaxation are considered and compared. It is shown that the\n'spin ballistic' regime is possible, when the phase relaxation length for the\nspin part of the wave function (WF)is much greater than the phase relaxation\nlength for the 'orbital part'. In the presence of an additional magnetic field,\nthe spin part of the electron's WF acquires a phase shift due to additional\nspin precession about that field. If the structure length is chosen to be\ngreater than the phase relaxation length for the 'orbital part' and less than\nthe phase relaxation length for the spin part of WF, it is possible to 'wash\nout' the quantum interference related to the phase coherence of the 'orbital\npart' of the WF, retaining at the same time that related to the phase coherence\nof the spin part and, hence, to reveal corresponding conductance oscillations."
    },
    {
        "anchor": "Transport Induced Dimer State from Topological Corner States: Recently, a new type of second-order topological insulator has been\ntheoretically proposed by introducing an in-plane Zeeman field into the\nKane-Mele model in the two-dimensional honeycomb lattice. A pair of topological\ncorner states arise at the corners with obtuse angles of an isolated\ndiamond-shaped flake. To probe the corner states, we study their transport\nproperties by attaching two leads to the system. Dressed by incoming electrons,\nthe dynamic corner state is very different from its static counterpart.\nResonant tunneling through the dressed corner state can occur by tuning the\nin-plane Zeeman field. At the resonance, the pair of spatially well separated\nand highly localized corner states can form a dimer state, whose wavefunction\nextends almost the entire bulk of the diamond-shaped flake. By varying the\nZeeman field strength, multiple resonant tunneling events are mediated by the\nsame dimer state. This re-entrance effect can be understood by a simple model.\nThese findings extend our understanding of dynamic aspects of the second-order\ntopological corner states.",
        "positive": "Out-of-plane equilibrium spin current in a quasi-two-dimensional\n  electron gas under in-plane magnetic field: Equilibrium spin-current is calculated in a quasi-two-dimensional electron\ngas with finite thickness under in-plane magnetic field and in the presence of\nRashba- and Dresselhaus spin-orbit interactions. The transverse confinement is\nmodeled by means of a parabolic potential. An orbital effect of the in-plane\nmagnetic field is shown to mix a transverse quantized spin-up state with\nnearest-neighboring spin-down states. The out-off-plane component of the\nequilibrium spin current appears to be not zero in the presence of an in-plane\nmagnetic field, provided at least two transverse-quantized levels are filled.\nIn the absence of the magnetic field the obtained results coincide with the\nwell-known results, yielding cubic dependence of the equilibrium spin current\non the spin-orbit coupling constants. The persistent spin-current vanishes in\nthe absence of the magnetic field if Rashba- and Dresselhaus spin-orbit\ncoefficients,{\\alpha} and {\\beta}, are equal each other. In-plane magnetic\nfield destroys this symmetry, and accumulates a finite spin-current as {\\alpha}\n\\rightarrow {\\beta}. Magnetic field is shown to change strongly the equilibrium\ncurrent of the in-plane spin components, and gives new contributions to the\ncubic-dependent on spin-orbit constants terms. These new terms depend linearly\non the spin-orbit constants."
    },
    {
        "anchor": "Evidence for Topological Protection Derived from Six-Flux Composite\n  Fermions: The composite fermion theory opened a new chapter in understanding many-body\ncorrelations through the formation of emergent particles. The formation of\ntwo-flux and four-flux composite fermions is well established. While there are\nlimited data linked to the formation of six-flux composite fermions,\ntopological protection associated with them is conspicuously lacking. Here we\nreport evidence for the formation of a quantized and gapped fractional quantum\nHall state at the filling factor $\\nu=9/11$, which we associate with the\nformation of six-flux composite fermions. Our result provides evidence for the\nmost intricate composite fermion with six fluxes and expands the already\ndiverse family of highly correlated topological phases with a new member that\ncannot be characterized by correlations present in other known members. Our\nobservations pave the way towards the study of higher order correlations in the\nfractional quantum Hall regime.",
        "positive": "High-harmonic spectroscopy of light-driven nonlinear anisotropic\n  anomalous Hall effect in a Weyl semimetal: Weyl semimetals are promising quantum materials that offer unique topological\nproperties. Lately, it has been shown that laser-driven electron dynamics have\ncharacteristic signatures in two-dimensional and three-dimensional Dirac\nsemimetals. The transition from Dirac to Weyl semimetal requires the breaking\nof either inversion or time-reversal symmetry. The present work shows that the\nlaser-driven electron dynamics in a Weyl semimetal with broken time-reversal\nsymmetry has intriguing features in its high-harmonic spectrum. It is found\nthat the parity and magnitude of the non-zero Berry curvature's components\ncontrol the direction and strength of the anomalous current, which leads to the\ngeneration of the anomalous odd harmonics. We demonstrate that the non-trivial\ntopology of the Berry curvature in time-reversal symmetry broken quantum\nmaterials can be probed by measuring the polarisation of the emitted anomalous\nodd harmonics. Our findings unequivocally illustrate that laser-driven electron\ndynamics leads to the generation of nonlinear anisotropic anomalous Hall effect\nin time-reversal symmetry broken quantum materials on an ultrafast timescale."
    },
    {
        "anchor": "Parity anomaly driven topological transitions in magnetic field: Recent developments in solid state physics give a prospect to observe the\nparity anomaly in (2+1)D massive Dirac systems. Here we show, that the quantum\nanomalous Hall (QAH) state in orbital magnetic fields originates from the Dirac\nmass term and induces an anomalous four-current related to the parity anomaly.\nThis differentiates the QAH from the quantum Hall (QH) state for the\nexperimentally relevant case of an effective constant density (seen by the\ngate). A direct signature of QAH phase in magnetic fields is a long\n$\\sigma_{xy}= e^2/h$ ($\\sigma_{xy}= -e^2/h$) plateau in\nCr$_x$(Bi$_{1-y}$Sb$_y$)$_{2-x}$Te$_3$ (HgMnTe quantum wells). Furthermore, we\npredict a new transition between the quantum spin Hall (QSH) and the QAH state\nin magnetic fields, for constant effective carrier density, without magnetic\nimpurities but driven by effective g-factors and particle-hole asymmetry. This\ntransition can be related to the stability of edge states in the Dirac mass gap\nof 2D topological insulators (TIs), even in high magnetic fields.",
        "positive": "Self-consistent electron counting statistics: We develop a self-consistent version of perturbation theory in Liouville\nspace which seeks to combine the advantages of master equation approaches in\nquantum transport with the nonperturbative features that a self-consistent\ntreatment brings. We describe how counting fields may be included in a\nself-consistent manner in this formalism such that the full counting statistics\ncan be calculated. NonMarkovian effects are also incorporated. Several\ndifferent self-consistent approximations are introduced and we discuss their\nrelative strengths with a simple example."
    },
    {
        "anchor": "Degenerate states of narrow semiconductor rings in the presence of spin\n  orbit coupling: Role of time-reversal and large gauge transformations: The electron Hamiltonian of narrow semiconductor rings with the Rashba and\nDresselhaus spin orbit terms is invariant under time-reversal operation\nfollowed by a large gauge transformation. We find that all the eigenstates are\ndoubly degenerate when integer or half-integer quantum fluxes thread the\nquantum ring. The wavefunctions of a degenerate pair are related to each other\nby the symmetry operation. These results are valid even in the presence of a\ndisorder potential. When the Zeeman term is present only some of these\ndegenerate levels anticross.",
        "positive": "Flat bands and gaps in twisted double bilayer graphene: We present electronic structure calculations of twisted double bilayer\ngraphene (TDBG): A tetralayer graphene structure composed of two AB-stacked\ngraphene bilayers with a relative rotation angle between them. Using\nfirst-principles calculations, we find that TDBG is semiconducting with a band\ngap that depends on the twist angle, that can be tuned by an external electric\nfield. The gap is consistent with TDBG symmetry and its magnitude is related to\nsurface effects, driving electron transfer from outer to inner layers. The\nsurface effect competes with an energy upshift of localized states at inner\nlayers, giving rise to the peculiar angle dependence of the band gap, which\nreduces at low angles. For these low twist angles, the TDBG develops flat\nbands, in which electrons in the inner layers are localized at the AA regions,\nas in twisted bilayer graphene."
    },
    {
        "anchor": "Klein tunneling and cone transport in AA-stacked bilayer graphene: We investigate the quantum tunneling of electrons in an AA-stacked bilayer\ngraphene (BLG) $n$-$p$ junction and $n$-$p$-$n$ junction. We show that Klein\ntunneling of an electron can occur in this system. The quasiparticles are not\nonly chiral but are additionally described by a `cone index'. Due to the\northogonality of states with different cone indexes, electron transport across\na potential barrier must strictly conserve the cone index and this leads to the\nprotected cone transport which is unique in AA-stacked BLG. Together with the\nnegative refraction of electrons, electrons residing in different cones can be\nspatially separated according to their cone index when transmitted across an\n$n$-$p$ junction. This suggests the possibility of `cone-tronic' devices based\non AA-stacked BLG. Finally, we calculate the junction conductance of the\nsystem.",
        "positive": "Timescale separation solution of Kadanoff-Baym equations for quantum\n  transport in time-dependent fields: The interaction with time-dependent external fields, especially the interplay\nbetween time-dependent driving and quantum correlations, changes the familiar\npicture of electron transport through nanoscale systems. Although the exact\nsolution of the problem of AC quantum transport of noninteracting electrons has\nbeen known for more than two decades, the treatment of correlated particles\npresents a significant theoretical challenge. In this paper, using the\nperturbative separation of fast electron tunnelling and slow driving\ntime-scales, we developed a practical approach for time-dependent quantum\ntransport with nonequilibrium Green's functions. The fast electronic dynamics\nis associated with relative time whilst the slow driving is related to the\ncentral time in the Green's functions. The ratio of characteristic electron\ntunneling time over the period of harmonic driving is used as a small parameter\nin the theory to obtain a convergent time-derivative expansions of the Green's\nfunctions. This enables the algebraic solution of the Kadanoff-Baym equations\nin Wigner space. Consequently, we produced analytical expressions for dynamical\ncorrections to advanced, retarded, and lesser Green's functions, as well as an\nimproved expression for AC electric current. The method developed is applicable\nto the general case of multi-channel electron transport through a correlated\ncentral region. The theory is applied to different transport scenarios:\ntime-dependent transport through a driven single-resonant level is compared to\nexact results; and electron transport through a molecular junction described by\nthe Holstein model with a time-oscillating voltage bias is also investigated."
    },
    {
        "anchor": "Spin-flip effects on the Andreev bound states and supercurrents in a\n  superconductor/quantum-dot/superconductor system: We investigate the spin-flip effects on the Andreev bound states and the\nsupercurrent in a superconductor/quantum-dot/superconductor system\ntheoretically. The spin-flip scattering in the quantum dot can reverse the\nsupercurrent flowing through the system, and one $\\pi$-junction transition\noccurs. By controlling the energy level of quantum dot, the supercurrent is\nreversed back and another $\\pi$-junction transition appears. The different\ninfluences of the spin-flip scattering and the intradot energy level on the\nsupercurrent are interpreted in the picture of Andreev bound states.",
        "positive": "Non-Gaussian Current Fluctuations in a Short Diffusive Conductor: We report the measurement of the third moment of current fluctuations in a\nshort metallic wire at low temperature. The data are deduced from the\nstatistics of voltage fluctuations across the conductor using a careful\ndetermination of environmental contributions. Our results at low bias agree\nvery well with theoretical predictions for coherent transport with no fitting\nparameter. By increasing the bias voltage we explore the cross-over from\nelastic to inelastic transport."
    },
    {
        "anchor": "Influence of the velocity barrier on the massive Dirac electron\n  transport in a monolayer MoS$_{2}$ quantum structure: Using the transfer matrix method, spin- and valley-dependent electron\ntransport properties modulated by the velocity barrier were studied in the\nnormal/ferromagnetic/normal monolayer MoS$_{2}$ quantum structure. Based on\nSnell's Law in optics, we define the velocity barrier as $\\xi=v_{2}/v_{1}$ by\nchanging the Fermi velocity of the intermediate ferromagnetic region to obtain\na deflection condition during the electron transport process in the structure.\nThe results show that both the magnitude and the direction of spin- and\nvalley-dependent electron polarization can be regulated by the velocity\nbarrier. $-100\\%$ polarization of spin- and valley-dependent electron can be\nachieved for $\\xi>1$, while $100\\%$ polarization can be obtained for $\\xi<1$.\nFurthermore, it is determined that perfect spin and valley transport always\noccur at a large incident angle. In addition, the spin- and valley-dependent\nelectron transport considerably depends on the length $k_{F}L$ and the gate\nvoltage $U(x)$ of the intermediate ferromagnetic region. These findings provide\nan effective method for designing novel spin and valley electronic devices.",
        "positive": "Fluctuation of inverse compressibility for electronic systems with\n  random capacitive matrices: This article is concerned with statistics of addition spectra for systems of\nidentical charged particles. A classical model is suggested in order to study\nfluctuations of Coulomb blockade peak spacings in large two-dimensional\nsemiconductor quantum dots. It is based on the electrostatics of several\nelectron islands among which there are random inductive and capacitive\ncouplings. Each island can accommodate electrons on quantum orbitals whose\nenergy depend also on an external magnetic field. | In contrast with a single\nisland quantum dot where the spacing distribution between conductance peaks is\nclose to Gaussian, here the distribution has a peak at small spacing value. The\nfluctuations are mainly due to charging effects. The model can explain the\noccasional occurrence of couples or even triples of closely spaced Coulomb\nblockade peaks, as well as the qualitative behavior of peak positions with the\napplied magnetic field."
    },
    {
        "anchor": "Observation of a Nematic Quantum Hall Liquid on the Surface of Bismuth: Nematic quantum fluids with wavefunctions that break the underlying\ncrystalline symmetry can form in interacting electronic systems. We examine the\nquantum Hall states that arise in high magnetic fields from anisotropic hole\npockets on the Bi(111) surface. Spectroscopy performed with a scanning\ntunneling microscope shows that a combination of local strain and many-body\nCoulomb interactions lift the six-fold Landau level (LL) degeneracy to form\nthree valley-polarized quantum Hall states. We image the resulting anisotropic\nLL wavefunctions and show that they have a different orientation for each\nbroken-symmetry state. The wavefunctions correspond precisely to those expected\nfrom pairs of hole valleys and provide a direct spatial signature of a nematic\nelectronic phase.",
        "positive": "Absorption of Light by Excitons and Trions in Monolayers of Metal\n  Dichalcogenide MoS$_{2}$: Experiments and Theory: We measure the optical absorption spectra and optical conductivities of\nexcitons and trions in monolayers of metal dichalcogenide MoS$_{2}$ and compare\nthe results with theoretical models. Our results show that the Wannier-Mott\nmodel for excitons, with modifications to account for small exciton radii and\nlarge exciton relative wavefunction spread in momentum space, phase space\nblocking due to Pauli exclusion in doped materials, and wavevector dependent\ndielectric constant, gives results that agree well with experiments. The\nmeasured exciton optical absorption spectra are used to obtain experimental\nestimates for the exciton radii that fall in the $7-10\\AA$ range and agree well\nwith theory. The measured trion optical absorption spectra are used to obtain\nvalues for the trion radii that also agree well with theory. The measured\nvalues of the exciton and trion radii correspond to binding energies that are\nin good agreement with values obtained from first principles calculations."
    },
    {
        "anchor": "The influence of magnetic-field-induced spin-density-wave motion and\n  finite temperature on the quantum Hall effect in quasi-one-dimensional\n  conductors: A quantum field theory: We derive the effective action for a moving magnetic-field-induced\nspin-density wave (FISDW) in quasi-one-dimensional conductors at zero and\nnonzero temperatures by taking the functional integral over the electron field.\nThe effective action consists of the (2+1)D Chern-Simons term and the (1+1)D\nchiral anomaly term, both written for a sum of the electromagnetic field and\nthe chiral field associated with the FISDW phase. The calculated frequency\ndependence of Hall conductivity interpolates between the quantum Hall effect at\nlow frequencies and zero Hall effect at high frequencies, where the counterflow\nof FISDW cancels the Hall current. The calculated temperature dependence of the\nHall conductivity is interpreted within the two-fluid picture, by analogy with\nthe BCS theory of superconductivity.",
        "positive": "Hofstadter butterfly and integer quantum Hall effect in three dimensions: For a three-dimensional lattice in magnetic fields we have shown that the\nhopping along the third direction, which normally tends to smear out the Landau\nquantization gaps, can rather give rise to a fractal energy spectram akin to\nHofstadter's butterfly when a criterion, found here by mapping the problem to\ntwo dimensions, is fulfilled by anisotropic (quasi-one-dimensional) systems. In\n3D the angle of the magnetic field plays the role of the field intensity in 2D,\nso that the butterfly can occur in much smaller fields. The mapping also\nenables us to calculate the Hall conductivity, in terms of the topological\ninvariant in the Kohmoto-Halperin-Wu's formula, where each of $\\sigma_{xy},\n\\sigma_{zx}$ is found to be quantized."
    },
    {
        "anchor": "Anomalous D'yakonov-Perel' spin relaxation in semiconductor quantum\n  wells under strong magnetic field in Voigt configuration: We report an anomalous scaling of the D'yakonov-Perel' spin relaxation with\nthe momentum relaxation in semiconductor quantum wells under a strong magnetic\nfield in the Voigt configuration. We focus on the case that the external\nmagnetic field is perpendicular to the spin-orbit-coupling--induced effective\nmagnetic field and its magnitude is much larger than the later one. It is found\nthat the longitudinal spin relaxation time is proportional to the momentum\nrelaxation time even in the strong scattering limit, indicating that the\nD'yakonov-Perel' spin relaxation shows the Elliott-Yafet-like behaviour.\nMoreover, the transverse spin relaxation time is inversely proportional\n(proportional) to the momentum relaxation time in the weak (strong) scattering\nlimit, both in the opposite trends against the well-established conventional\nD'yakonov-Perel' spin relaxation behaviours. We further demonstrate that all\nthe above anomalous scaling relations come from the unique form of the\neffective inhomogeneous broadening.",
        "positive": "Theoretical study of transport properties of B40 and its endohedral\n  borospherenes in single-molecule junctions: C60 fullerene has been studied extensively, as it is considered to be a good\ncandidate for building single-molecule junctions. Here, we theoretically\ndemonstrate that the conductance of single-molecule junctions based on a newly\ndiscovered molecule, borospherene (B40), is comparable to that for the\nC60-based junction with its more delocalized {\\pi} electrons. The charge\ninjection efficiency in the B40-based junction is improved, as up to 7 atoms in\ndirect contact with the electrode are possible in the Au-B40-Au junction.\nInterestingly, a higher number of atoms in direct contact with the electrode\ndoes not result in a higher number of conduction channels because of the unique\nchemical bonding in the B40 molecule, without two-center two- electron bonds.\nThe transport properties of Au-B40-Au junctions can be proved by doping. With a\nCa, Sr, or Y atom encapsulated into the B40 cage, the conductance at zero bias\nincreases significantly. Moreover, our calculations show that the lowest\nunoccupied molecular orbital dominates the low-bias transport, as the\nthermopower in these junctions is negative. Our study indicates that B40 is an\nattractive new platform for designing highly conductive single-molecule\njunctions for future molecular circuits."
    },
    {
        "anchor": "Bias induced up to 100% spin-injection and detection polarizations in\n  ferromagnet/bilayer-hBN/graphene/hBN heterostructures: We study spin transport in a fully hBN encapsulated monolayer-graphene van\nder Waals (vdW) heterostructure, at room temperature. A top-layer of\nbilayer-hBN is used as a tunnel barrier for spin-injection and detection in\ngraphene with ferromagnetic cobalt electrodes. We report surprisingly large and\nbias induced (differential) spin-injection (detection) polarizations up to 50%\n(135%) at a positive voltage bias of +0.6 V, as well as sign inverted\npolarizations up to -70% (-60%) at a reverse bias of -0.4 V. This demonstrates\nthe potential of bilayer-hBN tunnel barriers for practical graphene spintronics\napplications. With such enhanced spin-injection and detection polarizations, we\nreport a record two-terminal (inverted) spin-valve signals up to 800 $\\Omega$\nwith a magnetoresistance ratio of 2.7%, and we achieve spin accumulations up to\n4.1 meV. We propose how these numbers can be increased further, for future\ntechnologically relevant graphene based spintronic devices.",
        "positive": "Entanglement detection in coupled particle plasmons: When in close contact, plasmonic resonances interact and become strongly\ncorrelated. In this work we develop a quantum mechanical model, using the\nlanguage of continuous variables and quantum information, for an array of\ncoupled particle plasmons. This model predicts that when the coupling strength\nbetween plasmons approaches or surpasses the local dissipation, a sizable\namount of entanglement is stored in the collective modes of the array. We also\nprove that entanglement manifests itself in far-field images of the plasmonic\nmodes, through the statistics of the quadratures of the field, in what\nconstitutes a novel family of entanglement witnesses. This protocol is so\nrobust that it is indeed independent of whether our own model is correct.\nFinally, we estimate the amount of entanglement, the coupling strength and the\ncorrelation properties for a system that consists of two or more coupled\nnanospheres of silver, showing evidence that our predictions could be tested\nusing present-day state-of-the-art technology."
    },
    {
        "anchor": "Non-adiabatic current generation in a finite width semiconductor ring: We consider a model of a semiconductor quantum ring of finite width in a\nconstant perpendicular magnetic field. We show how a current of the same order\nas the persistent current can be generated non-adiabatically by a short\nintensive pulse in the Tera-Hertz regime.",
        "positive": "Homotopy invariant in time-reversal and twofold rotation symmetric\n  systems: The primary goal of this paper is to study topological invariants in two\ndimensional twofold rotation and time-reversal symmetric spinful systems. In\nthis paper, firstly we build a new homotopy invariant based on the lifting of\nthe Wilson loop to the universal covering group of the special orthogonal\ngroup. Furthermore, we prove that the invariant we built agrees with the K\ntheory invariant. We go beyond the previous understanding of the Wilson loop\nunwinding in more than two occupied bands by finding an obstruction of such\nunwinding. Then, within this formalism, we show two examples that have the same\nWilson loop spectrum but belong to different topological classes. Finally, we\npresent a tight binding model realizing the non-trivial phase."
    },
    {
        "anchor": "Effects of valence, geometry and electronic correlations on transport in\n  transition metal benzene sandwich molecules: We study the impact of the valence and the geometry on the electronic\nstructure and transport properties of different transition metal-benzene\nsandwich molecules bridging the tips of a Cu nanocontact. Our\ndensity-functional calculations show that the electronic transport properties\nof the molecules depend strongly on the molecular geometry which can be\ncontrolled by the nanocontact tips. Depending on the valence of the transition\nmetal center certain molecules can be tuned in and out of half-metallic\nbehaviour facilitating potential spintronics applications. We also discuss our\nresults in the framework of an Anderson impurity model, indicating cases where\nthe inclusion of local correlations alters the ground state qualitatively. For\nCo and V centered molecules we find indications of an orbital Kondo effect.",
        "positive": "Anomalous dissipation of nanomechanical modes going through nonlinear\n  resonance: We study nonlinear resonance of coupled modes in nano-mechanical systems. To\nreveal the qualitative features of the dynamics, we consider the limiting\ncases, where the results can be obtained analytically. For 1:3 resonance, we\nfind the anomalously strong and nonmonotonic dependence of the decay rate of\nthe low frequency mode on its amplitude, if the decay rate of the\nhigh-frequency mode is comparatively large. In this case the low-frequency mode\ndriven close to resonance can have several branches of steady-state vibrations\nwith constant amplitude. If the decay rates of the both modes are small\ncompared to their coupling and internal nonlinearity, the dynamics corresponds\nto slowly decaying strongly nonsinusoidal oscillations of the vibration\namplitude. Weak driving can make these vibrations stable."
    },
    {
        "anchor": "Large-Scale Statistical Analysis of Defect Emission in hBN: Revealing\n  Spectral Families and Influence of Flakes Morphology: Quantum emitters in two-dimensional layered hexagonal boron nitride are\nquickly emerging as a highly promising platform for next-generation quantum\ntechnologies. However, precise identification and control of defects are key\nparameters to achieve the next step in their development. We conducted a\ncomprehensive study by analyzing over 10,000 photoluminescence emission lines,\nrevealing 11 distinct defect families within the 1.6 to 2.2 eV energy range.\nThis challenges hypotheses of a random energy distribution. We also reported\naveraged defect parameters, including emission linewidths, spatial density,\nphonon side bands, and the Debye-Waller factors. These findings provide\nvaluable insights to decipher the microscopic origin of emitters in hBN hosts.\nWe also explored the influence of hBN host morphology on defect family\nformation, demonstrating its crucial impact. By tuning flake size and\narrangement we achieve selective control of defect types while maintaining high\nspatial density. This offers a scalable approach to defect emission control,\ndiverging from costly engineering methods. It highlights the importance of\ninvestigating flake morphological control to gain deeper insights into the\norigins of defects and to expand the spectral tailoring capabilities of defects\nin hBN.",
        "positive": "Ultrafast vibrational motion of carbon nanotubes in different pH\n  environments: We have used a femtosecond pump-probe impulsive Raman technique to explore\nthe ultrafast dynamics of micelle suspended single walled carbon nanotubes\n(SWNTs) in various pH environments. The structures of coherent phonon spectra\nof the radial breathing modes (RBMs) exhibit significant pH dependence, to\nwhich we attribute the effect of the protonation at the surface of SWNTs,\nresulting in the modification of electronic properties of semiconductor SWNTs.\nAnalysis of the time-domain data using a time-frequency transformation uncovers\nalso a second transient longitudinal breathing mode, which vanishes after 1 ps\nof the photoexcitation."
    },
    {
        "anchor": "In search of Majorana: Majorana particles are the same as their antiparticle, and their analogues in\ncondensed matter may be a platform for quantum computing. We describe the\nsearch for these modes in semiconductor heterostructures and how disorder is a\nlimiting factor.",
        "positive": "Driven-Dissipative Conductance in Nanojunction Arrays: Negative\n  Conductance and Light-Induced Currents: Stationary coherence in small conducting arrays has been shown to influence\nthe transport efficiency of electronic nanodevices. Model schemes that capture\nthe interplay between electron delocalization and system-reservoir interactions\non the device performance are therefore important for designing next-generation\nnanojunctions powered by quantum coherence. We use a Lindblad open quantum\nsystem approach to obtain the current-voltage characteristics of small-size\nnetworks of interacting conducting sites subject to radiative and non-radiative\ninteractions with the environment, for experimentally-relevant case studies.\nLindblad theory is shown to reproduce recent measurements of negative\nconductance in single-molecule junctions using a biased two-site model driven\nby thermal fluctuations. For array sites with conducting ground and excited\norbitals in the presence of radiative incoherent pumping, we show that Coulomb\ninteractions that otherwise suppress charge transport can be overcome to\nproduce light-induced currents. We also show that in nanojunctions having\nasymmetric transfer rates between the array and electrical contacts, an\nincoherent driving field can induce photocurrents at zero bias voltage whose\ndirection depend on the type or orbital delocalization established between\nsites. Possible extensions of the theory are discussed."
    },
    {
        "anchor": "Gate-defined Quantum Point Contact in an InSb Two-dimensional Electron\n  Gas: We investigate an electrostatically defined quantum point contact in a\nhigh-mobility InSb two-dimensional electron gas. Well-defined conductance\nplateaus are observed, and the subband structure of the quantum point contact\nis extracted from finite-bias measurements. The Zeeman splitting is measured in\nboth in-plane and out-of-plane magnetic fields. We find an in-plane g factor\n$|g_{\\parallel}^* | \\approx$ 40. The out-of-plane g factor is measured to be\n$|g_{\\perp}^* | \\approx$ 50, which is close to the g factor in the bulk.",
        "positive": "Spin polarisation by current: This is an overview of current-induced spin polarization in gyrotropic\nsemiconductor nanostructures. Such a spin polarization as response to a charge\ncurrent may be classified as the inverse of the spin-galvanic effect, and\nsometimes is called as magneto-electrical effect or Edelstein\n(Rashba-Edelstein) effect. Apart from reviewing the experimental status of\naffairs, we have provided a detailed theoretical description of both effects in\nterms of a phenomenological model of spin-dependent relaxation processes, and\nan alternative theoretical approach based on the quasi-classical Boltzmann\nequation."
    },
    {
        "anchor": "Electrically controllable exchange bias via interface magnetoelectric\n  effect: Exchange bias is a unidirectional magnetic anisotropy that often arise from\ninterfacial interaction of a ferromagnetic and antiferromagnetic layers. In\nthis article, we show that a metallic layer with spin-orbit coupling can\ninduces an exchange bias via an interface magnetoelectric effect. In linear\nresponse regime, the interface magnetoelectric effect is induced by spin-orbit\ncouplings that arises from the broken symmetry of the system. Furthermore, we\ndemonstrate that the exchange bias can be controlled by electric field.",
        "positive": "Dirac electron in graphene under supersymmetry generated magnetic fields: We use supersymmetry transformations to obtain new one parameter family of\ninhomogeneous magnetic fields $\\mathbf{B} = \\widetilde{\\mathcal{B}}(x,\\lambda)\n\\hat{e}_z$ for which the massless Dirac electron possesses exact solution. The\ninhomogeneity appearing in $\\widetilde{\\mathcal{B}}(x,\\lambda)$ can be\ncontrolled by the parameter $\\lambda$. The obtained magnetic fields are\ninterpreted as deformed variants of some physically attainable well known\nmagnetic fields. A particular example, when a constant magnetic field is\ndeformed, is considered to show that equidistant Landau levels exist even in\nthe presence of an infinite number of specially designed inhomogeneous magnetic\nfields."
    },
    {
        "anchor": "Quantum theory of longitudinal-transverse polaritons in nonlocal thin\n  films: When mid-infrared light interacts with nanoscale polar dielectric structures\noptical phonon propagation cannot be ignored, leading to a rich nonlocal\nphenomenology which we have only recently started to uncover. In properly\ncrafted nanodevices this includes the creation of polaritonic excitations with\nhybrid longitudinal-transverse nature, which are predicted to allow energy\nfunnelling from longitudinal electrical currents to far-field transverse\nradiation. In this work we study the physics of these longitudinal-transverse\npolaritons in a dielectric nanolayer in which the nonlocality strongly couples\nepsilon-near-zero modes to longitudinal phonons. After having calculated the\nsystem's spectrum solving Maxwell's equations, we develop an analytical\npolaritonic theory able to transparently quantify the nonlocality-mediated\ncoupling as a function of the system parameters. Such a theory provides a\npowerful tool for the study of longitudinal-transverse polariton interactions\nand we use it to determine the conditions required for the hybrid modes to\nappear.",
        "positive": "Current correlations in the interacting Cooper-pair beam-splitter: We propose an approach allowing the computation of currents and their\ncorrelations in interacting multiterminal mesoscopic systems involving quantum\ndots coupled to normal and/or superconducting leads. The formalism relies on\nthe expression of branching currents and noise crossed correlations in terms of\none- and two-particle Green's functions for the dots electrons, which are then\nevaluated self-consistently within a conserving approximation. We then apply\nthis to the Cooper-pair beam-splitter setup recently proposed [L. Hofstetter et\nal. Nature (London) 461 960 (2009); Phys. Rev. Lett. 107 136801 (2011); L. G.\nHerrmann et al. Phys. Rev. Lett. 104 026801 (2010)], which we model as a double\nquantum dot with weak interactions, connected to a superconducting lead and two\nnormal ones. Our method not only enables us to take into account a local\nrepulsive interaction on the dots, but also to study its competition with the\ndirect tunneling between dots. Our results suggest that even a weak Coulomb\nrepulsion tends to favor positive current cross correlations in the\nantisymmetric regime (where the dots have opposite energies with respect to the\nsuperconducting chemical potential)."
    },
    {
        "anchor": "On Injection in Intrinsic Single-Carrier Devices: By considering the changes in the interface charge-carrier densities of a\nsingle-carrier device as a function of injection-barrier heights and comparing\nthese to the equilibrium, background charge-carrier density of a device with\nOhmic contacts, we calculate simple conditions for when these barriers are\nexpected to limit injection and therefore significantly affect\nspace-charge-limited currents in the device. We show that these conditions\ndepend on the device temperature, semiconductor relative permittivity, and\neffective density of states, but most importantly the thickness of the\nsemiconducting film being probed. This is in accordance with previous\nobservations and similar derived expressions for when defects influence\nsingle-carrier devices. The conditions described herein can be used to aid the\ndesign of single-carrier devices for space-charge-limited current measurements\nthat are not limited by injection.",
        "positive": "A cold-source paradigm for steep-slope transistors based on van der\n  Waals heterojunctions: The availability of transistors capable of operating at low supply voltage is\nessential to improve the key performance metric of computing circuits, i.e.,\nthe number of operations per unit energy. In this paper, we propose a new\ndevice concept for energy-efficient, steep-slope transistors based on\nheterojunctions of 2D materials. We show that by injecting electrons from an\nisolated and weakly dispersive band into a strongly dispersive one,\nsubthermionic subthreshold swings can be obtained, as a result of a cold-source\neffect and of a reduced thermalization of carriers. This mechanism is\nimplemented by integrating in a MOSFET architecture two different monolayer\nmaterials coupled through a van der Waals heterojunction, combining the\nsubthermionic behavior of tunnel field-effect transistors (FETs) with the\nrobustness of a MOSFET architecture against performance-degrading factors, such\nas traps, band tails and roughness. A further advantage with respect to tunnel\nFETs is that only an n-type or p-type doping is required to fabricate the\ndevice. In order to demonstrate the device concept and to discuss the\nunderlying physics and the design options, we study through abinitio and\nfull-quantum transport simulations a possible implementation that exploits two\nrecently reported 2D materials."
    },
    {
        "anchor": "Nonlocal magnetolectric effects in diffusive conductors with spatially\n  inhomogeneous spin-orbit coupling: We present a theoretical study of nonlocal magnetoelectric effects in\ndiffusive hybrid structures with an intrinsic linear-in-momentum spin-orbit\ncoupling (SOC) which is assumed to be spatially inhomogeneous. Our analysis is\nbased on the SU(2)-covariant drift-diffusion equations from which we derive the\nBC at hybrid interfaces. Within this formulation, the spin current is\ncovariantly conserved when the spin relaxation is only due to the intrinsic\nSOC. This conservation leads to the absence of spin Hall (SH) currents in\nhomogeneous systems. We also consider extrinsic sources of relaxation (ESR), as\nmagnetic impurities, which break the covariant spin conservation, and may lead\nto SH currents. We apply our model to describe nonlocal transport in a system\nwith an interface separating two regions: one normal region without intrinsic\nSOC and one with a Rashba SOC. We first explore the inverse spin-galvanic\neffect, i.e., a spin polarization induced by an electric field. We demonstrate\nhow the spatial behavior of such spin density depends on both, the direction of\nthe electric field and the strength of the ESR rate. We also study the\nspin-to-charge conversion, and compute the charge current and the distribution\nof electrochemical potential in the Rashba region induced by a spin current\ninjected into the normal region. In systems with an inhomogeneous SOC varying\nin one spatial direction, we find an interesting nonlocal reciprocity between\nthe spin density induced by a charge current at a given point in space, and the\nspatially integrated current induced by a spin density injected at the same\npoint.",
        "positive": "Ab-initio Dynamics of Rare Thermally Activated Reactions: We introduce a framework to investigate ab-initio the dynamics of rare\nthermally activated reactions. The electronic degrees of freedom are described\nat the quantum-mechanical level in the Born-Oppenheimer approximation, while\nthe nuclear degrees of freedom are coupled to a thermal bath, through a\nLangevin equation. This method is based on the path integral representation for\nthe stochastic dynamics and yields the time evolution of both nuclear and\nelectronic degrees of freedom, along the most probable reaction pathways,\nwithout spending computational time to explore metastable states. This approach\nis very efficient and allows to study thermally activated reactions which\ncannot be simulated using ab-initio molecular dynamics techniques. As a first\nillustrative application, we characterize the dominant pathway in the\ncyclobutene to butadiene reaction."
    },
    {
        "anchor": "Observation of Distinct Electron-Phonon Couplings in Gated Bilayer\n  Graphene: A Raman study of a back gated bilayer graphene sample is presented. The\nchanges in the Fermi level induced by charge transfer splits the Raman G-band,\nhardening its higher component and softening the lower one. These two\ncomponents are associated with the symmetric (S) and anti-symmetric vibration\n(AS) of the atoms in the two layers, the later one becoming Raman active due to\ninversion symmetry breaking. The phonon hardening and softening are explained\nby considering the selective coupling of the S and AS phonons with interband\nand intraband electron-hole pairs.",
        "positive": "Spin relaxation in sub-monolayer and monolayer InAs structures grown in\n  GaAs matrix: Electron spin dynamics in InAs/GaAs heterostructures consisting of a single\nlayer of InAs (1/3$\\sim$1 monolayer) embeded in (001) and (311)A GaAs matrix\nwas studied by means of time-resolved Kerr rotation spectroscopy. The spin\nrelaxation time of the sub-monolayer InAs samples is significantly enhanced,\ncompared with that of the monolayer InAs sample. We attributed the slowing of\nthe spin relaxation to dimensionally constrained\nD\\textquoteright{}yakonov-Perel\\textquoteright{} mechanism in the motional\nnarrowing regime. The electron spin relaxation time and the effective g-factor\nin sub-monolayer samples were found to be strongly dependent on the\nphoton-generated carrier density. The contribution from both\nD\\textquoteright{}yakonov-Perel\\textquoteright{} mechanism and Bir-Aronov-Pikus\nmechanism were discussed to interpret the temperature dependence of spin\ndecoherence at various carrier densities."
    },
    {
        "anchor": "Conductance quantization in graphene nanoconstrictions with\n  mesoscopically smooth but atomically stepped boundaries: We present the results of million atom electronic quantum transport\ncalculations for graphene nanoconstrictions with edges that are smooth apart\nfrom atomic scale steps. We find conductances quantized in integer multiples of\n2e2/h and a plateau at ~0.5*2e2/h as in recent experiments [Tombros et al.,\nNature Physics 7, 697 (2011)]. We demonstrate that, surprisingly, conductances\nquantized in integer multiples of 2e2/h occur even for strongly non-adiabatic\nelectron backscattering at the stepped edges that lowers the conductance by one\nor more conductance quanta below the adiabatic value. We also show that\nconductance plateaus near 0.5*2e2/h can occur as a result of electron\nbackscattering at stepped edges even in the absence of electron-electron\ninteractions.",
        "positive": "Low temperature Hall effect in bismuth chalcogenides thin films: Bismuth chalcogenides are the most studied 3D topological insulators. As a\nrule, at low temperatures thin films of these materials demonstrate positive\nmagnetoresistance due to weak antilocalization. Weak antilocalization should\nlead to resistivity decrease at low temperatures; in experiments, however,\nresistivity grows as temperature decreases. From transport measurements for\nseveral thin films (with various carrier density, thickness, and carrier\nmobility), and by using purely phenomenological approach, with no microscopic\ntheory, we show that the low temperature growth of the resistivity is\naccompanied by growth of the Hall coefficient, in agreement with diffusive\nelectron-electron interaction correction mechanism. Our data reasonably explain\nthe low-temperature resistivity upturn."
    },
    {
        "anchor": "Imaging ferroelectric domains with a single-spin scanning quantum sensor: The ability to sensitively image electric fields is important for\nunderstanding many nanoelectronic phenomena, including charge accumulation at\nsurfaces and interfaces and field distributions in active electronic devices. A\nparticularly exciting application is the visualization of domain patterns in\nferroelectric and nanoferroic materials owing to their potential in computing\nand data storage. Here, we use a scanning nitrogen-vacancy (NV) microscope,\nwell known for its use in magnetometry, to image domain patterns in\npiezoelectric (Pb[Zr$_{x}$Ti$_{1-x}$]O$_{3}$) and improper ferroelectric\n(YMnO$_{3}$) materials through their electric fields. Electric field detection\nis enabled by measuring the Stark shift of the NV spin using a gradiometric\ndetection scheme. Analysis of the electric field maps allows us to discriminate\nbetween different types of surface charge distributions, as well as to\nreconstruct maps of the three-dimensional electric field vector and charge\ndensity. The ability to measure both stray electric and magnetic fields under\nambient conditions opens exciting opportunities for the study of multiferroic\nand multifunctional materials and devices.",
        "positive": "Vacuum-induced coherence in quantum dot systems: We present a theoretical study of vacuum-induced coherence in a pair of\nvertically stacked semiconductor quantum dots. The process consists in a\ncoherent excitation transfer from a single-exciton state localized in one dot\nto a delocalized state in which the exciton occupation gets trapped. We study\nthe influence of the factors characteristic of quantum dot systems (as opposed\nto natural atoms): energy mismatch, coupling between the single exciton states\nlocalized in different dots, different and non-parallel dipoles due to subband\nmixing, as well as coupling to phonons. We show that the destructive effect of\nthe energy mismatch can be overcome by an appropriate interplay of the dipole\nmoments and coupling between the dots which allows one to observe the trapping\neffect even in a structure with technologically realistic energy splitting on\nthe order of milli-electron-Volts. We also analyze the impact of phonon\ndynamics on the occupation trapping and show that phonon effects are suppressed\nin a certain range of system parameters. This analysis shows that the vacuum\ninduced coherence effect and the associated long-living trapped excitonic\npopulation can be achieved in quantum dots."
    },
    {
        "anchor": "Spin-entangled currents created by a triple quantum dot: We propose a simple setup of three coupled quantum dots in the Coulomb\nblockade regime as a source for spatially separated currents of spin-entangled\nelectrons. The entanglement originates from the singlet ground state of a\nquantum dot with an even number of electrons. To preserve the entanglement of\nthe electron pair during its extraction to the drain leads, the electrons are\ntransported through secondary dots. This prevents one-electron transport by\nenergy mismatch, while joint transport is resonantly enhanced by conservation\nof the total two-electron energy.",
        "positive": "On-demand thermoelectric generation of equal-spin Cooper pairs: Superconducting spintronics is based on the creation of spin-triplet Cooper\npairs in ferromagnet-superconductor (F-S) hybrid junctions. Previous proposals\nto manipulate spin-polarized supercurrents on-demand typically require the\nability to carefully control magnetic materials. We, instead, propose a quantum\nheat engine that generates equal-spin Cooper pairs and drives supercurrents\non-demand without manipulating magnetic components. We consider a S-F-S\njunction, connecting two leads at different temperatures, on top of the helical\nedge of a two-dimensional topological insulator. Heat and charge currents\ngenerated by the thermal bias are caused by different transport processes,\nwhere electron cotunneling is responsible for the heat flow to the cold lead\nand, strikingly, only crossed Andreev reflections contribute to the charge\ncurrent. Such a purely nonlocal Andreev thermoelectric effect injects\nspin-polarized Cooper pairs at the superconductors, generating a supercurrent\nthat can be switched on/off by tuning their relative phase. We further\ndemonstrate that signatures of spin-triplet pairing are facilitated by rather\nlow fluctuations of the thermoelectric current for temperature gradients\nsmaller than the superconducting gap."
    },
    {
        "anchor": "Orbital Magnetization in Insulators: Bulk vs. Surface: The orbital magnetic moment of a finite piece of matter is expressed in terms\nof the one-body density matrix as a simple trace. We address a macroscopic\nsystem, insulating in the bulk, and we show that its orbital moment is the sum\nof a bulk term and a surface term, both extensive. The latter only occurs when\nthe transverse conductivity is nonzero and owes to conducting surface states.\nSimulations on a model Hamiltonian validate our theory.",
        "positive": "KH2PO4 + Host Matrix (Alumina / SiO$_2$) Nanocomposite: Raman Scattering\n  Insight: We report on the synthesis and Raman scattering characterization of composite\nmaterials based on the hostnanoporous matrices filled with nanostructured\nKH2PO4 (KDP) crystal. Silica (SiO2) and anodized aluminium oxide (AAO) were\nused as host matrices with various pore diameters, inter-pore spacing and\nmorphology. The structure of the nanocomposites was investigated by X-ray\ndiffraction and scanning electron microscopy. Raman scattering reveals the\ncreation of one-dimensional nanostructured KDP inside the SiO2 matrix. We\nclearly observed the stretching {\\nu}1, {\\nu}3 and bending {\\nu}2 vibrations of\nPO4 tetrahedral groups in the Raman spectrum of SiO2 + KDP. In Raman scattering\nspectra of AAO + KDP nanocomposite, the broad fluorescence background of AAO\nmatrix dominates to a great extent, hindering thus the detecting of the KDP\ncompound spectral response."
    },
    {
        "anchor": "Stable charge density wave phase in a 1T-TiSe$_2$ monolayer: Charge density wave (CDW) phases are symmetry-reduced states of matter in\nwhich a periodic modulation of the electronic charge frequently leads to\ndrastic changes of the electronic spectrum, including the emergence of energy\ngaps. We analyze the CDW state in a 1T-TiSe$_2$ monolayer within a density\nfunctional theory framework and show that, similarly to its bulk counterpart,\nthe monolayer is unstable towards a commensurate $2{\\times}2$ periodic lattice\ndistortion (PLD) and CDW at low temperatures. Analysis of the electron and\nphonon spectrum establishes the PLD as the stable $T=0$ K configuration with a\nnarrow bandgap, whereas the undistorted and semi-metalic state is stable only\nabove a threshold temperature. The lattice distortions as well as the unfolded\nand reconstructed band structure in the CDW phase agree well with experimental\nresults. We also address evidence in our results for the role of\nelectron-electron interactions in the CDW instability of 1T-TiSe$_2$\nmonolayers.",
        "positive": "Coexistence of two- and three-dimensional Shubnikov-de Haas oscillations\n  in Ar^+ -irradiated KTaO_3: We report the electron doping in the surface vicinity of KTaO_3 by inducing\noxygen-vacancies via Ar^+ -irradiation. The doped electrons have high mobility\n(> 10^4 cm^2/Vs) at low temperatures, and exhibit Shubnikov-de Haas\noscillations with both two- and three-dimensional components. A disparity of\nthe extracted in-plane effective mass, compared to the bulk values, suggests\nmixing of the orbital characters. Our observations demonstrate that Ar^+\n-irradiation serves as a flexible tool to study low dimensional quantum\ntransport in 5d semiconducting oxides."
    },
    {
        "anchor": "Phonon-mediated spin dynamics in a two-electron double quantum dot under\n  a phonon temperature gradient: We have theoretically studied phonon-mediated spin-flip processes of\nelectrons in a GaAs double quantum dot (DQD) holding two spins, under a phonon\ntemperature gradient over the DQD. Transition rates of inter-dot\nphonon-assisted tunnel processes and intra-dot spin-flip processes involving\nspin triplet states are formalized by the electron-phonon interaction\naccompanied with the spin-orbit interaction. The calculations of the spin-flip\nrates and the occupation probabilities of the spin-states in the two-electron\nDQD with respect to the phonon temperature difference between the dots are\nquantitatively consistent with our previous experiment. This theoretical study\non the temperature gradient effect onto spins in coupled QDs would be essential\nfor understanding spin-related thermodynamic physics.",
        "positive": "Andreev reflection in edge states of time reversal invariant Landau\n  levels: We describe the conductance of a normal-superconducting junction in systems\nwith Landau levels that preserve time reversal symmetry. Those Landau levels\nhave been observed in strained honeycomb lattices. The current is carried along\nthe edges in both the normal and superconducting regions. When the Landau\nlevels in the normal region are half-filled, Andreev reflection is maximal and\nthe conductance plateaus have a peak as a function of filling factor. The\nheight of those peaks is quantized at $4e^{2}/h$. The interface of the junction\nhas Andreev edge states, which form a coherent superposition of electrons and\nholes that can carry a net valley current. We identify unique experimental\nsignatures for superconductivity in time reversal invariant Landau levels."
    },
    {
        "anchor": "Engineering inter-qubit exchange coupling between donor bound electrons\n  in silicon: We investigate the electrical control of the exchange coupling (J) between\ndonor bound electrons in silicon with a detuning gate bias, crucial for the\nimplementation of the two-qubit gate in a silicon quantum computer. We find the\nasymmetric 2P-1P system provides a highly tunable exchange-curve with mitigated\nJ-oscillation, in which 5 orders of magnitude change in the exchange energy can\nbe achieved using a modest range of electric field for 15 nm qubit separation.\nCompared to the barrier gate control of exchange in the Kane qubit, the\ndetuning gate design reduces the demanding constraints of precise donor\nseparation, gate width, density and location, as a range of J spanning over a\nfew orders of magnitude can be engineered for various donor separations. We\nhave combined a large-scale full band atomistic tight-binding method with a\nfull configuration interaction technique to capture the full two-electron\nspectrum of gated donors, providing state-of-the-art calculations of exchange\nenergy in 1P-1P and 2P-1P qubits.",
        "positive": "Excitons in Phosphorene: A Semi-Analytical Perturbative Approach: In this paper we develop a semi-analytical perturbation-theory approach to\nthe calculation of the energy levels (binding energies) and wave functions of\nexcitons in phosphorene. Our method gives both the exciton wave function in\nreal and reciprocal spaces with the same ease. This latter aspect is important\nfor the calculation of the nonlinear optical properties of phosphorene. We find\nthat our results are in agreement with calculations based both on the\nBethe-Salpeter equation and on Monte Carlo simulations, which are\ncomputationally much more demanding. Our approach thus introduces a simple,\nviable, and accurate method to address the problem of excitons in anisotropic\ntwo-dimensional materials."
    },
    {
        "anchor": "Nonlinear optical response of doped mono- and bilayer graphene: length\n  gauge tight-binding model: We compute the nonlinear optical response of doped mono- and bilayer graphene\nusing the full dispersion based on tight-binding models. The response is\nderived with the density matrix formalism using the length gauge and is valid\nfor any periodic system, with arbitrary doping. By collecting terms that define\neffective nonlinear response tensors, we identify all nonlinear Drude-like\nterms (up to third-order) and show that all additional spurious divergences\npresent in the induced current vanish. The nonlinear response of graphene\ncomprises a large Drude-like divergence and three resonances that are tightly\nconnected with transitions occurring in the vicinity of the Fermi level. The\nanalytic solution derived using the Dirac approximation captures accurately the\nfirst- and third-order responses in graphene, even at very high doping levels.\nThe quadratic response of gapped graphene is also strongly enhanced by doping,\neven for systems with small gaps such as commensurate structures of graphene on\nSiC. The nonlinear response of bilayer graphene is significantly richer,\ncombining the resonances that stem from doping with its intrinsic strong\nlow-energy resonances.",
        "positive": "Thermal infrared emission reveals the Dirac point movement in biased\n  graphene: Graphene is a 2-dimensional material with high carrier mobility and thermal\nconductivity, suitable for high-speed electronics. Conduction and valence bands\ntouch at the Dirac point. The absorptivity of single-layer graphene is 2.3%,\nnearly independent of wavelength. Here we investigate the thermal radiation\nfrom biased graphene transistors. We find that the emission spectrum of\nsingle-layer graphene follows that of a grey body with constant emissivity (1.6\n\\pm 0.8)%. Most importantly, we can extract the temperature distribution in the\nambipolar graphene channel, as confirmed by Stokes/anti-Stokes measurements.\nThe biased graphene exhibits a temperature maximum whose location can be\ncontrolled by the gate voltage. We show that this peak in temperature reveals\nthe spatial location of the minimum in carrier density, i.e. the Dirac point."
    },
    {
        "anchor": "Modeling of novel lateral AlGaAs/GaAs quantum well solar cell: In this paper, a novel lateral quantum well solar cell has been introduced,\nand the structural parameters effects of these nano-structures on the\nperformance of the device have been investigated. For modeling, the continuity\nequation has been solved in the quasi neutral regions. However, to analyze the\nquantum wells' effects, first the Schrodinger and Poisson equations have been\nsolved self-consistently. To find the absorption coefficient derived from the\nFermi's golden rule, the obtained Eigen states and energies and also the\neffects of multilayers using Transfer Matrix Method have been employed. Then,\nto find the solar cell performance parameters, all radiative and non-radiative\nrecombinations have been accounted. It is found that modifying different\ngeometrical parameters, including the thickness of the system, the widths of\nthe wells and barriers, and also some structural parameters such as the\nbarriers' mole fraction could noticeably influence the characteristics of the\ndevice. So, optimizing these parameters is necessary to obtain a good\nefficiency.",
        "positive": "Maximizing Spin Torque Diode Voltage by Optimizing Magnetization\n  Alignment: The optimum condition of the magnetization alignment to maximize the spin\ntorque diode voltage is derived by solving the Landau-Lifshitz-Gilbert\nequation. We show that the optimized diode voltage can be one order of\nmagnitude larger than that of the conventional alignment where the easy axes of\nthe free and the pinned layers are parallel. These analytical predictions are\nconfirmed by numerical simulations."
    },
    {
        "anchor": "Measurement of the Energy Gap of Au55 Nanoparticles Using Far-infrared\n  Transmission Spectroscopy: We have carried out far-infrared (far-IR) transmission measurements on the\nligand stabilized Au55 nanoparticles dispersed in Teflon at volume fractions\nranging from 0.2% to 1%. Instead of a series of peaks which might arise from\nthe electron transition between discrete energy levels, we have observed a\nbroad far-IR absorption coefficient that follows with an onset at {\\Delta} ~ 10\ncm-1. Furthermore this frequency dependence is totally different from that of\nthe expected absorption due to the induced electric dipole. The onset of the\nabsorption reminiscent of an energy gap at ~ 10 cm-1 (~ 1. 2 meV) is\nsurprisingly smaller than that of the expected for a metal sphere of 5.3 {\\AA}\nin radius and independent of temperature. In this work we did not observe the\nlevel correlation effect on the far-IR absorption predicted for an ensemble of\nmetal nanoparticles. It is concluded that Au55 nanoparticles behave like a\nthree-dimensional (3D) semimetal with an energy gap {\\Delta} ~ 10 cm-1 rather\nthan a giant atom.",
        "positive": "Effect of deconfinement on resonant transport in quantum wires: The effect of deconfinement due to finite band offsets on transport through\nquantum wires with two constrictions is investigated. It is shown that the\nincrease in resonance linewidth becomes increasingly important as the size is\nreduced and ultimately places an upper limit on the energy (temperature) scale\nfor which resonances may be observed."
    },
    {
        "anchor": "Time Reversal Polarization and a Z_2 Adiabatic Spin Pump: We introduce and analyze a class of one dimensional insulating Hamiltonians\nwhich, when adiabatically varied in an appropriate closed cycle, define a\n\"$Z_2$ pump\". For an isolated system a single closed cycle of the pump changes\nthe expectation value of the spin at each end even when spin orbit interactions\nviolate the conservation of spin. A second cycle, however returns the system to\nits original state. When coupled to leads, we show that the $Z_2$ pump\nfunctions as a spin pump in a sense which we define, and transmits a finite,\nthough non quantized spin in each cycle. We show that the $Z_2$ pump is\ncharacterized by a $Z_2$ topological invariant that is analogous to the Chern\ninvariant that characterizes a topological charge pump. The $Z_2$ pump is\nclosely related to the quantum spin Hall effect, which is characterized by a\nrelated $Z_2$ invariant. This work presents an alternative formulation which\nclarifies both the physical and mathematical meaning of that invariant. A\ncrucial role is played by time reversal symmetry, and we introduce the concept\nof the time reversal polarization, which characterizes time reversal invariant\nHamiltonians and signals the presence or absence of Kramers degenerate end\nstates. For non interacting electrons we derive a formula for the time reversal\npolarization which is analogous to the Berry's phase formulation of the charge\npolarization. For interacting electrons, we show that abelian bosonization\nprovides a simple formulation of the time reversal polarization. We discuss\nimplications for the quantum spin Hall effect, and argue in particular that the\n$Z_2$ classification of the quantum spin Hall effect is valid in the presence\nof electron electron interactions.",
        "positive": "Interaction-driven transport of dark excitons in 2D semiconductors with\n  phonon-mediated optical readout: The growing field of quantum information technology requires propagation of\ninformation over long distances with efficient readout mechanisms. Excitonic\nquantum fluids have emerged as a powerful platform for this task due to their\nstraightforward electro-optical conversion. In two-dimensional transition metal\ndichalcogenides, the coupling between spin and valley provides exciting\nopportunities for harnessing, manipulating and storing bits of information.\nHowever, the large inhomogeneity of single layers cannot be overcome by the\nproperties of bright excitons, hindering spin-valley transport. Nonetheless,\nthe rich band structure supports dark excitonic states with strong binding\nenergy and longer lifetime, ideally suited for long-range transport. Here we\nshow that dark excitons can diffuse over several micrometers and prove that\nthis repulsion-driven propagation is robust across non-uniform samples. The\nlong-range propagation of dark states with an optical readout mediated by\nchiral phonons provides a new concept of excitonic devices for applications in\nboth classical and quantum information technology."
    },
    {
        "anchor": "Ultrastrong Coupling of Band-Nested Excitons in Few-Layer Molybdenum\n  Disulphide: The two-dimensional transition-metal dichalcogenides (2D TMDCs) are an\nintriguing platform for studying light-matter interactions because they combine\nthe electronic properties of conventional semiconductors with the optical\nresonances found in organic systems. However, the coupling strengths\ndemonstrated in strong exciton-polariton coupling remain much lower than those\nfound in organic systems. In this paper, we take on a new approach by utilizing\nthe large oscillator strength of the above-band gap C exciton in few-layer\nmolybdenum disulphide ($\\text{FL-MoS}_2$). We show a k-space Rabi splitting of\n293 meV when coupling $\\text{FL-MoS}_2$ C excitons to surface plasmon\npolaritons at room temperature. This value is 11% of the uncoupled exciton\nenergy (2.67 eV or 464 nm), ~2x what is typically seen in the TMDCs, placing\nthe system in the ultrastrong coupling regime. Our results take a step towards\nfinally achieving the efficient quantum coherent processes of ultrastrong\ncoupling in a CMOS-compatible system -- the 2D TMDCs -- in the visible\nspectrum.",
        "positive": "Topological water wave state in a one-dimensional structure: Topological concepts have been introduced into electronic, photonic, and\nphononic systems, but have not been studied in surface-water-wave systems. Here\nwe study a one-dimensional periodic resonant surface-water-wave system and\ndemonstrate its topological transition. By selecting three different water\ndepths, we can construct different types of water waves - shallow, intermediate\nand deep water waves. The periodic surface-water-wave system consists of an\narray of cylindrical water tanks connected with narrow water channels. As the\nwidth of connecting channel varies, the band diagram undergoes a topological\ntransition which can be further characterized by Zak phase. This topological\ntransition holds true for shallow, intermediate and deep water waves. However,\nthe interface state at the boundary separating two topologically distinct\narrays of water tanks can exhibit different bands for shallow, intermediate and\ndeep water waves. Our work studies for the first time topological properties of\nwater wave systems, and paves the way to potential management of water waves."
    },
    {
        "anchor": "The Study of Goldstone Modes in $\u03bd$=2 Bilayer Quantum Hall Systems: At the filling factor $\\nu$=2, the bilayer quantum Hall system has three\nphases, the spin-ferromagnet phase, the spin singlet phase and the canted\nantiferromagnet (CAF) phase, depending on the relative strength between the\nZeeman energy and interlayer tunneling energy. We present a systematic method\nto derive the effective Hamiltonian for the Goldstone modes in these three\nphases. We then investigate the dispersion relations and the coherence lengths\nof the Goldstone modes. To explore a possible emergence of the interlayer phase\ncoherence, we analyze the dispersion relations in the zero tunneling energy\nlimit. We find one gapless mode with the linear dispersion relation in the CAF\nphase.",
        "positive": "Selective coherent phonon mode generation in single wall carbon\n  nanotubes: The pulse-train technique within ultrafast pump-probe spectroscopy is\ntheoretically investigated to enhance a specific coherent phonon mode while\nsuppressing the other phonon modes generated in single wall carbon nanotubes\n(SWNTs). In particular, we focus on the selectivity of the radial breathing\nmode (RBM) and the G-band for a given SWNT. We find that if the repetition\nperiod of the pulse train matches with integer multiple of the RBM phonon\nperiod, the RBM amplitude could be kept while the amplitudes of the other modes\nare suppressed. As for the G-band, when we apply a repetition period of\nhalf-integer multiple of the RBM period, the RBM could be suppressed because of\ndestructive interference, while the G-band still survives. It is also possible\nto keep the G-band and suppress the RBM by applying a repetition period that\nmatches with integer multiple of the G-band phonon period. However, in this\ncase we have to use a large number of laser pulses having a property of \"magic\nratio\" of the G-band and RBM periods."
    },
    {
        "anchor": "Bimodal switching field distributions in all-perpendicular spin-valve\n  nanopillars: Switching field measurements of the free layer element of 75 nm diameter\nspin-valve nanopillars reveal a bimodal distribution of switching fields at low\ntemperatures (below 100 K). This result is inconsistent with a model of thermal\nactivation over a single perpendicular anisotropy barrier. The correlation\nbetween antiparallel to parallel and parallel to antiparallel switching fields\nincreases to nearly 50% at low temperatures. This reflects random fluctuation\nof the shift of the free layer hysteresis loop between two different\nmagnitudes, which may originate from changes in the dipole field from the\npolarizing layer. The magnitude of the loop shift changes by 25% and is\ncorrelated to transitions of the spin-valve into an antiparallel configuration.",
        "positive": "Electrically Controllable van der Waals Antiferromagnetic Spin Valve: We propose a spin valve that is based on van der Waals antiferromagnetism and\nfully electrically controlled. The device is composed of two antiferromagnetic\nterminals that allow for vertical bias control and a linked central scattering\npotential region. The magnetoresistance varies significantly when the bias\norientations in two terminals are switched from parallel to antiparallel\nbecause this switch induces a mismatch of the bands for the same spin\nprojection in different parts of the system. It is shown from density\nfunctional calculations that bilayer graphene encapsulated by two atomic layers\nof Cr$_2$Ge$_2$Te$_6$ provides a material platform to realize the\nantiferromagnetism, which is robust against the required vertical electric\nfields."
    },
    {
        "anchor": "Nonperturbative Topological Model of Synergistic Phase of 2D Electron\n  Gas Induced by Microwave Excitation: The synergistic formation of ``zero'' (exponentially small or thermally\nactivated) resistance states (ESRS) in high mobility two-dimensional electron\nsystems (2DES) in a static magnetic field B and exposed to strong microwave\nradiation has attracted great interest. Strong (glassy) disorder apparently\nstabilizes the new synergistic phase, which can be exactly described by a\nnonperturbative (nonpolynomial) microscopic topological filamentary model. The\nmodel contains many novel features that arise from strong correlations,\nnanoscopic phase separation, and quasi-one dimensional back scattering.",
        "positive": "Magnetoelectric Andreev effect due to proximity-induced non-unitary\n  triplet superconductivity in helical metals: Non-centrosymmetric superconductors exhibit the magnetoelectric effect which\nmanifests itself in the appearance of the magnetic spin polarization in\nresponse to a dissipationless electric current (supercurrent). While much\nattention has been dedicated to the thermodynamic version of this phenomenon\n(Edelstein effect), non-equilibrium transport magnetoelectric effects have not\nbeen explored yet. We propose the magnetoelectric Andreev effect (MAE) which\nconsists in the generation of spin-polarized triplet Andreev conductance by an\nelectric supercurrent. The MAE stems from the spin polarization of the\nCooper-pair condensate due to a supercurrent-induced non-unitary triplet\npairing. We propose the realization of such non-unitary pairing and MAE in\nsuperconducting proximity structures based on two-dimensional helical metals --\nstrongly spin-orbit-coupled electronic systems with the Dirac spectrum such as\nthe topological surface states. Our results uncover an unexplored route towards\nelectrically controlled superconducting spintronics and are a smoking gun for\ninduced unconventional superconductivity in spin-orbit-coupled materials."
    },
    {
        "anchor": "Current-induced magnetic superstructures in exchange-spring devices: We investigate the potential to use a magneto-thermo-electric instability\nthat may be induced in a mesoscopic magnetic multi-layer (F/f/F) to create and\ncontrol magnetic superstructures. In the studied multilayer two strongly\nferromagnetic layers (F) are coupled through a weakly ferromagnetic spacer (f)\nby an \"exchange spring\" with a temperature dependent \"spring constant\" that can\nbe varied by Joule heating caused by an electrical dc current. We show that in\nthe current-in-plane (CIP) configuration a distribution of the magnetization,\nwhich is homogeneous in the direction of the current flow, is unstable in the\npresence of an external magnetic field if the length L of the sample in this\ndirection exceeds some critical value Lc ~ 10 \\mu m. This spatial instability\nresults in the spontaneous formation of a moving domain of magnetization\ndirections, the length of which can be controlled by the bias voltage in the\nlimit L >> Lc. Furthermore, we show that in such a situation the\ncurrent-voltage characteristics has a plateau with hysteresis loops at its ends\nand demonstrate that if biased in the plateau region the studied device\nfunctions as an exponentially precise current stabilizer.",
        "positive": "On-demand generation of background--free single photons from a\n  solid-state source: True on--demand high--repetition--rate single--photon sources are highly\nsought after for quantum information processing applications. However, any\ncoherently driven two-level quantum system suffers from a finite re-excitation\nprobability under pulsed excitation, causing undesirable multi--photon\nemission. Here, we present a solid--state source of on--demand single photons\nyielding a raw second--order coherence of $g^{(2)}(0)=(7.5\\pm1.6)\\times10^{-5}$\nwithout any background subtraction nor data processing. To this date, this is\nthe lowest value of $g^{(2)}(0)$ reported for any single--photon source even\ncompared to the previously best background subtracted values. We achieve this\nresult on GaAs/AlGaAs quantum dots embedded in a low--Q planar cavity by\nemploying (i) a two--photon excitation process and (ii) a filtering and\ndetection setup featuring two superconducting single--photon detectors with\nultralow dark-count rates of $(0.0056\\pm0.0007) s^{-1}$ and $(0.017\\pm0.001)\ns^{-1}$, respectively. Re--excitation processes are dramatically suppressed by\n(i), while (ii) removes false coincidences resulting in a negligibly low noise\nfloor."
    },
    {
        "anchor": "Nuclear spin relaxation rate near the disorder-driven quantum critical\n  point in Weyl fermion systems: Disorder such as impurities and dislocations in Weyl semimetals (SMs) drives\na quantum critical point (QCP) where the density of states at the Weyl point\ngains a non-zero value. Near the QCP, the asymptotic low energy singularities\nof physical quantities are controlled by the critical exponents $\\nu$ and $z$.\nThe nuclear spin-lattice relaxation rate, which originates from the hyperfine\ncoupling between a nuclear spin and long-range orbital currents in Weyl fermion\nsystems, shows intriguing critical behavior. Based on the self-consistent Born\napproximation for impurities, we study the nuclear spin-lattice relaxation rate\n$1/T_1$ due to the orbital currents in disordered Weyl SMs. We find that\n$(T_1T)^{-1}\\sim E^{2/z}$ at the QCP where $E$ is the maximum of temperature\n$T$ and chemical potential $\\mu(T)$ relative to the Weyl point. This scaling\nbehavior of $(T_1T)^{-1}$ is also confirmed by the self-consistent $T$-matrix\napproximation, where a remarkable temperature dependence of $\\mu(T)$ could play\nan important role. We hope these results of $(T_1T)^{-1}$ will serve as an\nimpetus for exploration of the disorder-driven quantum criticality in Weyl\nmaterials.",
        "positive": "The mechanism of caesium intercalation of graphene: Properties of many layered materials, including copper- and iron-based\nsuperconductors, topological insulators, graphite and epitaxial graphene can be\nmanipulated by inclusion of different atomic and molecular species between the\nlayers via a process known as intercalation. For example, intercalation in\ngraphite can lead to superconductivity and is crucial in the working cycle of\nmodern batteries and supercapacitors. Intercalation involves complex diffusion\nprocesses along and across the layers, but the microscopic mechanisms and\ndynamics of these processes are not well understood. Here we report on a novel\nmechanism for intercalation and entrapment of alkali-atoms under epitaxial\ngraphene. We find that the intercalation is adjusted by the van der Waals\ninteraction, with the dynamics governed by defects anchored to graphene\nwrinkles. Our findings are relevant for the future design and application of\ngraphene-based nano-structures. Similar mechanisms can also play a role for\nintercalation of layered materials."
    },
    {
        "anchor": "Topological cutoff frequency in a slab waveguide: Penetration length in\n  topological insulator walls: We study the propagation of electromagnetic (EM) waves in a slab-type\nwaveguide which walls consist of three-dimensional topological insulator (3D\nTI). The results show that a cutoff frequency with topological stability limits\nthe spectrum that propagates along the waveguide and are in agreement with\nexperimental observations. Our approach also provides a way to measure the\npenetration length of surface metallic states in 3D TI.",
        "positive": "Casimir force among spheres made of Weyl semimetals breaking Lorentz\n  reciprocity: The Casimir force and thermal Casimir force originating from quantum\nelectromagnetic fluctuations at zero and non-zero temperatures, respectively,\nare significant in nano- and microscale systems and are well-understood. Less\nunderstood, however, are the Casimir and thermal Casimir forces in systems\nbreaking Lorentz reciprocity. In this work, we derive a formalism for thermal\nCasimir forces between an arbitrary number of spheres based on fluctuational\nelectrodynamics and scattering theory without the assumption of Lorentz\nreciprocity. We study the total Casimir force in systems of two and three Weyl\nsemimetal spheres with time-reversal symmetry breaking for different\norientations of the momentum-space separation of Weyl nodes in both thermal\nequilibrium and nonequilibrium. In thermal nonequilibrium, we show that a net\nthermal Casimir force exists not only along the center-to-center displacements\nof the spheres, but also in the transverse direction to it due to thermal\nemission with non-zero angular momentum. Different symmetries of the system\ndrive a variety of dynamics such as global rotations, self-propulsion, and\nspinning of the spheres. We also show that the Casimir energy in thermal\nequilibrium depends on the orientations of the Weyl node directions in the\nspheres and that the lateral Casimir force will act between the spheres even in\nthermal equilibrium to relax the system into the minimum energy state without\ntransferring net energy and momentum to the environment. The developed\nframework opens a way for investigating many-body dynamics by Casimir and\nthermal Casimir forces among arbitrary number of spheres with arbitrary\ndielectric function tensors in both thermal equilibrium and nonequilibrium."
    },
    {
        "anchor": "Resonant Bragg quantum wells in hybrid photonic crystals: The exciton-polariton propagation in resonant hybrid (isotropic/anisotropic)\nperiodic stacks, with misaligned in plane anisotropy and Bragg photon frequency\nin resonance with Wannier exciton of 2D quantum wells, is studied by\nself-consistent theory and in the effective mass approximation. The optical\ntailoring of this new class of resonant Bragg re ectors, where the structural\nperiodicity of a multi-layer drives the periodicity of the in-plane optical ^ C\naxis orientation, is computed for symmetric and non-symmetric elementary cell\nby conserving strong radiation-matter coupling and photonic band gap. We will\ndemonstrate, by selected numerical examples, that the behavior of the so called\nintermediate dispersion curves (IDC), that drop between upper and lower\nbranches of the lowest energy band gap, are strongly dependent from in-plane ^\nC axis orientation. Therefore, we guess that this class of hybrid\nmeta-materials is promising for new trapping light optical devices based on IDC\nbehavior.",
        "positive": "Rashba coupling and Lifshitz transition in monolayer graphene: We take a wide-angle view of the problem of monolayer graphene (MLG) where\nspin-degeneracy lifting is assumed to be possible by wedging in the tunable\nRashba spin-orbit coupling(RSOC) and the sub-lattice staggered potential. We\nnext consider the AB-stacked bi-layer graphene (BLG) system (the A-carbon of\nthe upper sheet lying on top of the B-carbon of the lower one) and assume that\na perpendicular electric field is created by the external gates deposited on\nthe BLG surface. This system exhibits the occurrence of trigonal warping due to\na (skew) interlayer hopping leading to the well-known Lifshitz\ntransition(LT)[Y. Lemonik, I.L. Aleiner, C. Toke, and V.I. Fal'ko;\narXiv:1006.1399]. We do not observe the replication of the features associated\nwith BLG-LT in MLG in the presence of RSOC."
    },
    {
        "anchor": "Wetting layer evolution and its temperature dependence during self\n  assembly of InAs/GaAs quantum dots: For InAs/GaAs(001) quantum dot (QD) system, the wetting layer (WL) evolution\nand its temperature dependence were studied using reflectance difference\nspectroscopy (RDS) and analyzed with a rate equation model. The WL thicknesses\nshowed a monotonic increase at relatively low growth temperatures but a first\nincrease and then decrease at higher temperatures, which were unexpected from\nthe thermodynamic understanding. By adopting a rate equation model, the\ntemperature dependence of QD growth was assigned as the origin of different WL\nevolutions. A brief discussion on the indium desorption was also given. Those\nresults gave hints of the kinetic aspects of QD self-assembly.",
        "positive": "Quantum dot to disordered wire crossover: A complete solution in all\n  length scales for systems with unitary symmetry: We present an exact solution of a supersymmetric nonlinear sigma model\ndescribing the crossover between a quantum dot and a disordered quantum wire\nwith unitary symmetry. The system is coupled ideally to two electron reservoirs\nvia perfectly conducting leads sustaining an arbitrary number of propagating\nchannels. We obtain closed expressions for the first three moments of the\nconductance, the average shot-noise power and the average density of\ntransmission eigenvalues. The results are complete in the sense that they are\nnonperturbative and are valid in all regimes and length scales. We recover\nseveral known results of the recent literature by taking particular limits."
    },
    {
        "anchor": "Theory of magnetic small-angle neutron scattering of two-phase\n  ferromagnets: Based on micromagnetic theory we have derived analytical expressions for the\nmagnetic small-angle neutron scattering (SANS) cross section of a two-phase\nparticle-matrix-type ferromagnet. The approach---valid close to magnetic\nsaturation---provides access to several features of the spin structure such as\nperturbing magnetic anisotropy and magnetostatic fields. Depending on the\napplied magnetic field and on the magnitude $H_p$ of the magnetic anisotropy\nfield relative to the magnitude $\\Delta M$ of the jump in the longitudinal\nmagnetization at the particle-matrix interface, we observe a variety of angular\nanisotropies in the magnetic SANS cross section. In particular, the model\nexplains the \"clover-leaf\"-shaped angular anisotropy which was previously\nobserved for several nanostructured magnetic materials, and it provides access\nto the magnetic interaction parameters such as the average exchange-stiffness\nconstant. It is also shown that the ratio $H_p / \\Delta M$ decisively\ndetermines the asymptotic power-law exponent and the range of spin-misalignment\ncorrelations.",
        "positive": "Charged Excitons of Composite Fermions in the Fractional Quantum Hall\n  Effect: Charged excitons of composite fermions (CFs) are considered in the fractional\nquantum Hall effect. Energies of the charged CF excitons are computed at\n$\\nu=1/3$ as a function of the size of exciton. We show that the charged CF\nexciton with size of roton is lower in energy than the unbound state of a\nneutral roton and a lone charge. Therefore we propose that the lowest-energy\nexcitation of the fractional quantum Hall effect is in fact due to the charged\nexcitons of composite fermions composed of two CF-particles and one CF-hole. We\nbelieve that charged excitons of composite fermions shed new light on\ninterpreting the resonant inelastic light scattering experiments."
    },
    {
        "anchor": "Observation of the 4$\u03c0$-periodic Josephson effect in indium arsenide\n  nanowires: Quantum computation by non-Abelian Majorana zero modes (MZMs) offers an\napproach to achieve fault tolerance by encoding quantum information in the\nnon-local charge parity states of semiconductor nanowire networks in the\ntopological superconductor regime. Thus far, experimental studies of MZMs\nchiefly relied on single electron tunneling measurements which leads to\ndecoherence of the quantum information stored in the MZM. As a next step\ntowards topological quantum computation, charge parity conserving experiments\nbased on the Josephson effect are required, which can also help exclude\nsuggested non-topological origins of the zero bias conductance anomaly. Here we\nreport the direct measurement of the Josephson radiation frequency in InAs\nnanowires with epitaxial aluminium shells. For the first time, we observe the\n$4\\pi$-periodic Josephson effect above a magnetic field of $\\approx 200\\,$mT,\nconsistent with the estimated and measured topological phase transition of\nsimilar devices.",
        "positive": "Effective Floquet model for minimally twisted bilayer graphene: We construct an effective Floquet lattice model for the triangular network\nthat emerges in interlayer-biased minimally twisted bilayer graphene and which\nsupports two chiral channels per link for a given valley and spin. We introduce\nthe Floquet scheme with the one-channel triangular network and subsequently\nextend it to the two-channel case. From the bulk topological index (winding\nnumber) and finite system calculations, we find that both cases host anomalous\nFloquet insulators (AFIs) with a different gap-opening mechanism. In the\none-channel network, either time-reversal or in-plane inversion symmetry has to\nbe broken to open a gap. In contrast, in the two-channel network, interchannel\ncoupling can open a gap without breaking these symmetries yielding a valley AFI\nwith counterpropagating edge states. This phase is topologically trivial with\nrespect to the total winding number but robust in the absence of intervalley\nscattering. Finally, we demonstrate the applicability of the Floquet model with\nmagnetotransport calculations."
    },
    {
        "anchor": "Spin-valve Effect in Nanoscale Si-based Devices: The silicon (Si) based spin-MOSFET (metal-oxide semiconductor field-effect\ntransistor) is considered to be the building block of low-power-consumption\nelectronics, utilizing spin-degrees of freedom in semiconductor devices. In\nthis paper, we review the latest results on the spin transport in nanoscale\nSi-based spin-valve devices, which is important to realize the nanoscale\nspin-MOSFET. Our results demonstrate the importance of ballistic transport in\nobtaining high spin-dependent output voltage in nanoscale Si spin-valve\ndevices.",
        "positive": "Magnetic field induced inequivalent vortex zero modes in strained\n  graphene: Zero energy states in the Dirac spectrum with U(1) symmetric massive vortices\nof various underlying insulating orders in strained graphene are constructed in\nthe presence of the magnetic field. An easy plane vortex of antiferromagnet and\nquantum spin Hall orders host two zero energy states, however, with two\ndifferent length scales. Such inequivalent zero modes can lead to oscillatory\ncharge and magnetization, and their usual quantizations get restored only far\nfrom the vortex core. Otherwise, these zero modes can be delocalized from each\nother by tuning the mutual strength of two fields. One can, therefore,\neffectively bind a single zero mode in the vortex core. A possible experimental\nset up to capture signature of this theory in real graphene as well as in\noptical honeycomb lattices is mentioned. Generalization of this scenario with\nunderlying topological defects of Kekule superconductors can localize a single\nMajorana mode in the vicinity of the defect-core."
    },
    {
        "anchor": "Sagnac interferometry for high-sensitivity optical measurements of\n  spin-orbit torque: Sagnac interferometry can provide a significant improvement in\nsignal-to-noise ratio compared to conventional magnetic imaging based on the\nmagneto-optical Kerr effect (MOKE). We show that this improvement is sufficient\nto allow quantitative measurements of current-induced magnetic deflections due\nto spin-orbit torque even in thin-film magnetic samples with perpendicular\nmagnetic anisotropy for which the Kerr rotation is second-order in the magnetic\ndeflection. Sagnac interfermometry can also be applied beneficially for samples\nwith in-plane anisotropy, for which the Kerr rotation is first order in the\ndeflection angle. Optical measurements based on Sagnac interferometry can\ntherefore provide a cross-check on electrical techniques for measuring\nspin-orbit torque. Different electrical techniques commonly give quantitatively\ninconsistent results, so that Sagnac interferometry can help to identify which\ntechniques are affected by unidentified artifacts.",
        "positive": "Optically controlled spin-polarization memory effect on Mn delta-doped\n  heterostrucutres: We investigated the dynamics of the interaction between spin-polarized\nphoto-created carriers and Mn ions on InGaAs/GaAs:Mn structures. The carriers\nare confined in an InGaAs quantum well and the Mn ions come from a Mn\ndelta-layer grown at the GaAs barrier close to the well. Even though the\ncarriers and the Mn ions are spatially separated, the interaction between them\nis demonstrated by time-resolved spin-polarized photoluminescence measurements.\nUsing a pre-pulse laser excitation with an opposite circular-polarization\nclearly reduces the polarization degree of the quantum-well emission for\nsamples where a strong magnetic interaction is observed. The results\ndemonstrate that the Mn ions act as a spin-memory that can be optically\ncontrolled by the polarization of the photocreated carriers. On the other hand,\nthe spin-polarized Mn ions also affect the spin-polarization of the\nsubsequently created carriers as observed by their spin relaxation time. These\neffects fade away with increasing time delays between the pulses as well as\nwith increasing temperatures."
    },
    {
        "anchor": "Phonon-assisted tunneling regimes in diatomic molecules: Electronic transport in diatomic molecules (two-level systems) connected to\nmetallic contacts is analyzed in the presence of competing electron-electron\nand electron-phonon interactions. We show that phonon emission and absorption\nprocesses are strongly modified when a Coulomb energy $U$ is included, as the\nphonons open channels that can result in destructive or constructive\ninterference effects. Resonance conditions for these processes produce dramatic\neffects both in the density of states at the molecular sites, as well as in the\nconductance through the system. We find in particular an enhanced {\\it\nRabi-assisted tunneling} due to phonons, as the resonance conditions are met,\nwhich is made more evident for increasing temperatures. These effects are\ncontrollable by voltage gating of the molecular sites, and should be accessible\nin current experiments.",
        "positive": "Photonic Spin Hall Effect in Waveguides Composed of Two Types of\n  Single-Negative Metamaterials: The polarization controlled optical signal routing has many important\napplications in photonics such as polarization beam splitter. By using\ntwo-dimensional transmission lines with lumped elements, we experimentally\ndemonstrate the selective excitation of guided modes in waveguides composed of\ntwo kinds of single-negative metamaterials. A localized, circularly polarized\nemitter placed near the interface of the two kinds of single-negative\nmetamaterials only couples with one guided mode with a specific propagating\ndirection determined by the polarization handedness of the source. Moreover,\nthis optical spin-orbit locking phenomenon, also called the photonic spin Hall\neffect, is robust against interface fluctuations, which may be very useful in\nthe manipulation of electromagnetic signals."
    },
    {
        "anchor": "Dynamics of superconducting nanowires shunted with an external resistor: We present the first study of superconducting nanowires shunted with an\nexternal resistor, geared towards understanding and controlling coherence and\ndissipation in nanowires. The dynamics is probed by measuring the evolution of\nthe V-I characteristics and the distributions of switching and retrapping\ncurrents upon varying the shunt resistor and temperature. Theoretical analysis\nof the experiments indicates that as the value of the shunt resistance is\ndecreased, the dynamics turns more coherent presumably due to stabilization of\nphase-slip centers in the wire and furthermore the switching current approaches\nthe Bardeen's prediction for equilibrium depairing current. By a detailed\ncomparison between theory and experimental, we make headway into identifying\nregimes in which the quasi-one-dimensional wire can effectively be described by\na zero-dimensional circuit model analogous to the RCSJ (resistively and\ncapacitively shunted Josephson junction) model of Stewart and McCumber. Besides\nits fundamental significance, our study has implications for a range of\npromising technological applications.",
        "positive": "Electrical and ELectronic Properties of Strained Mono-layer InTe: In this paper, electrical and electronic properties of strained mono-layer\nInTe for two structures, $\\alpha$, and $\\beta$ phases, is investigated. The\nband structure is obtained using density functional theory (DFT). The minimum\nenergy and effective mass of the conduction band and second conduction band for\ndifferent strains are calculated. A FET with using InTe as the channel material\nis investigated. Voltage-current characteristics of InTe FET is calculated and\nI$_{ON}$/I$_{OFF}$ ratio is obtained with respect to biaxial strain."
    },
    {
        "anchor": "Dissipation-enabled hydrodynamic conductivity in a tunable bandgap\n  semiconductor: Electronic transport in the regime where carrier-carrier collisions are the\ndominant scattering mechanism has taken on new relevance with the advent of\nultraclean two-dimensional materials. Here we present a combined theoretical\nand experimental study of ambipolar hydrodynamic transport in bilayer graphene\ndemonstrating that the conductivity is given by the sum of two Drude-like terms\nthat describe relative motion between electrons and holes, and the collective\nmotion of the electron-hole plasma. As predicted, the measured conductivity of\ngapless, charge-neutral bilayer graphene is sample- and temperature-independent\nover a wide range. Away from neutrality, the electron-hole conductivity\ncollapses to a single curve, and a set of just four fitting parameters provides\nquantitative agreement between theory and experiment at all densities,\ntemperatures, and gaps measured. This work validates recent theories for\ndissipation-enabled hydrodynamic conductivity and creates a link between\nsemiconductor physics and the emerging field of viscous electronics.",
        "positive": "Advances in coherent coupling between magnons and acoustic phonons: The interaction between magnetic and acoustic excitations have recently\ninspired many interdisciplinary studies ranging from fundamental physics to\ncircuit implementation. Specifically, the exploration of their coherent\ninterconversion enabled via the magnetoelastic coupling opens a new playground\ncombining straintronics and spintronics, and provides a unique platform for\nbuilding up on-chip coherent information processing networks with miniaturized\nmagnonic and acoustic devices. In this Perspective, we will focus on the recent\nprogress of magnon-phonon coupled dynamic systems, including materials,\ncircuits, imaging and new physics. In particular, we highlight the unique\nfeatures such as nonreciprocal acoustic wave propagation and strong coupling\nbetween magnons and phonons in magnetic thin-film systems, which provides a\nunique platform for their coherent manipulation and transduction. We will also\nreview the frontier of surface acoustic wave resonators in coherent quantum\ntransduction and discuss how the novel acoustic circuit design can be applied\nin microwave spintronics."
    },
    {
        "anchor": "Stabilization of carbon nanotubes by filling with inner tubes: An\n  optical spectroscopy study on double-walled carbon nanotubes under\n  hydrostatic pressure: The stabilization of carbon nanotubes via the filling with inner tubes is\ndemonstrated by probing the optical transitions in double-walled carbon\nnanotube bundles under hydrostatic pressure with optical spectroscopy.\nDouble-walled carbon nanotube films were prepared from fullerene peapods and\ncharacterized by HRTEM and optical spectroscopy. In comparison to single-walled\ncarbon nanotubes, the pressure-induced redshifts of the optical transitions in\nthe outer tubes are significantly smaller below $\\sim$10 GPa, demonstrating the\nenhanced mechanical stability due to the inner tube already at low pressures.\nAnomalies at the critical pressure P$_d$$\\approx$12 GPa signal the onset of the\npressure-induced deformation of the tubular cross-sections. The value of P$_d$\nis in very good agreement with theoretical predictions of the pressure-induced\nstructural transitions in double-walled carbon nanotube bundles with similar\naverage diameters.",
        "positive": "Electron Spin Relaxation in Graphene Nanoribbon Quantum Dots: Graphene is promising as a host material for electron spin qubits because of\nits predicted potential for long coherence times. In armchair graphene\nnanoribbons (aGNRs) a small bandgap is opened, allowing for electrically gated\nquantum dots, and furthermore the valley degeneracy is lifted. The spin\nlifetime T_1 is limited by spin relaxation, where the Zeeman energy is absorbed\nby lattice vibrations, mediated by spin-orbit and electron-phonon coupling. We\nhave calculated T_1 by treating all couplings analytically and find that T_1\ncan be in the range of seconds for several reasons: (i) low phonon density of\nstates away from Van Hove singularities; (ii) destructive interference between\ntwo relaxation mechanisms; (iii) Van Vleck cancellation at low magnetic fields;\n(iv) vanishing coupling to out-of-plane modes in lowest order due to the\nelectronic structure of aGNRs. Owing to the vanishing nuclear spin of 12C, T_1\nmay be a good measure for overall coherence. These results and recent advances\nin the controlled production of graphene nanoribbons make this system\ninteresting for spintronics applications."
    },
    {
        "anchor": "A New Paradigm for Edge Reconstruction in Fractional Quantum Hall States: Questions on the nature of edge reconstruction and \"where does the current\nflow\" in the quantum Hall effect (QHE) have been debated for years. Moreover,\nthe recent observation of proliferation of \"upstream\" neutral modes in the\nfractional QHE raised doubts about the present models of edge channels. In this\narticle we focus on hole-conjugate states, nu=2/3 and nu=3/5, and present a new\npicture of their edge reconstruction. For example, while the present model for\nnu=2/3 consists of a single downstream charge channel with conductance 2/3\ne^2/h and an upstream neutral mode, we show that the current is carried by two\nseparate downstream edge channels, each with conductance 1/3 e^2/h, accompanied\nby upstream neutral mode(s). We find that if the two downstream channels are\nnot equilibrated, inter-mode equilibration (via particle exchange) takes place\nover a distance of microns, with the two channels effectively behaving as a\nsingle channel. Moreover, the inter-channel equilibration is accompanied by an\nexcitation of upstream neutral modes. In turn, the counter-propagating neutral\nmodes, moving in close proximity to the charge modes, fragment into propagating\ncharges, inducing thus downstream current fluctuations with zero net current -\na novel mechanism for non-equilibrium noise. This unexpected edge\nreconstruction underlines the need for better understanding of edge\nreconstruction and energy transport in all fractional QHE states.",
        "positive": "Elastic scattering of slow electrons by carbon nanotubes: In this paper we calculate the elastic scattering cross sections of slow\nelectron by carbon nanotubes. The corresponding electron-nanotube interaction\nis substituted by a zero-thickness cylindrical potential that neglects the\natomic structure of real nanotubes, thus limiting the range of applicability of\nour approach to sufficiently low incoming electron energies. The strength of\nthe potential is chosen the same that was used in describing scattering of\nelectrons by fullerene C60. We present results for total and partial electron\nscattering cross sections as well as respective angular distributions, all with\naccount of five lowest angular momenta contributions. In the calculations we\nassumed that the incoming electron moves perpendicular to the nanotube axis,\nsince along the axis the incoming electron moves freely."
    },
    {
        "anchor": "Modal theory of modified spontaneous emission for a hybrid plasmonic\n  photonic-crystal cavity system: We present an analytical modal description of the rich physics involved in\nhybrid plasmonic-photonic devices that is confirmed by full dipole solutions of\nMaxwell's equations. Strong frequency-dependence for the spontaneous emission\ndecay rate of a quantum dipole emitter coupled to these hybrid structures is\npredicted. In particular, it is shown that the Fano-type resonances reported\nexperimentally in hybrid plasmonic systems, arise from a very large\ninterference between dominant quasinormal modes of the systems in the frequency\nrange of interest. The presented model forms an efficient basis for modelling\nquantum light-matter interactions in these complex hybrid systems and also\nenables the quantitativ prediction and understanding of non-radiative coupling\nlosses.",
        "positive": "Recent progress in open quantum systems: Non-Gaussian noise and\n  decoherence in fermionic systems: We review our recent contributions to two topics that have become of interest\nin the field of open, dissipative quantum systems: non-Gaussian noise and\ndecoherence in fermionic systems. Decoherence by non-Gaussian noise, i.e. by an\nenvironment that cannot be approximated as a bath of harmonic oscillators, is\nimportant in nanostructures (e.g. qubits) where there might be strong coupling\nto a small number of fluctuators. We first revisit the pedagogical example of\ndephasing by classical telegraph noise. Then we address two models where the\nquantum nature of the noise becomes essential: \"quantum telegraph noise\" and\ndephasing by electronic shot noise. In fermionic systems, many-body aspects and\nthe Pauli principle have to be taken care of when describing the loss of phase\ncoherence. This is relevant in electronic quantum transport through metallic\nand semiconducting structures. Specifically, we recount our recent results\nregarding dephasing in a chiral interacting electron liquid, as it is realized\nin the electronic Mach-Zehnder interferometer. This model can be solved\nemploying the technique of bosonization as well as a physically transparent\nsemiclassical method."
    },
    {
        "anchor": "Geometric energy transport and refrigeration with driven quantum dots: We study geometric energy transport in a slowly driven single-level quantum\ndot weakly coupled to electronic contacts and with strong onsite interaction,\nwhich can be either repulsive or attractive. Exploiting a recently discovered\nfermionic duality for the evolution operator of the master equation, we provide\ncompact and insightful analytic expressions of energy pumping curvatures for\nany pair of driving parameters. This enables us to systematically identify and\nexplain the pumping mechanisms for different driving schemes, thereby also\ncomparing energy and charge pumping. We determine the concrete impact of\nmany-body interactions and show how particle-hole symmetry and fermionic\nduality manifest, both individually and in combination, as system-parameter\nsymmetries of the energy pumping curvatures. Building on this transport\nanalysis, we study the driven dot acting as a heat pump or refrigerator, where\nwe find that the sign of the onsite interaction plays a crucial role in the\nperformance of these thermal machines.",
        "positive": "Magnetoresistance of heavy and light metal/ferromagnet bilayers: We studied the magnetoresistance of normal metal (NM)/ferromagnet (FM)\nbilayers in the linear and nonlinear (current-dependent) regimes and compared\nit with the amplitude of the spin-orbit torques and thermally induced electric\nfields. Our experiments reveal that the magnetoresistance of the heavy NM/Co\nbilayers (NM = Ta, W, Pt) is phenomenologically similar to the spin Hall\nmagnetoresistance (SMR) of YIG/Pt, but has a much larger anisotropy, of the\norder of 0.5%, which increases with the atomic number of the NM. This SMR-like\nbehavior is absent in light NM/Co bilayers (NM = Ti, Cu), which present the\nstandard AMR expected of polycrystalline FM layers. In the Ta, W, Pt/Co\nbilayers we find an additional magnetoresistance, directly proportional to the\ncurrent and to the transverse component of the magnetization. This so-called\nunidirectional SMR, of the order of 0.005%, is largest in W and correlates with\nthe amplitude of the antidamping spin-orbit torque. The unidirectional SMR is\nbelow the accuracy of our measurements in YIG/Pt."
    },
    {
        "anchor": "Superfluidity and collective properties of excitonic polaritons in\n  gapped graphene in a microcavity: We predict the formation and superfluidity of polaritons in an optical\nmicrocavity formed by excitons in gapped graphene embedded there and\nmicrocavity photons. The Rabi splitting related to the creation of an exciton\nin a graphene layer in the presence of the band gap is obtained. The analysis\nof collective excitations as well as the sound velocity is presented. We show\nthat the superfluid density and temperature of the Kosterlitz-Thouless phase\ntransition are decreasing functions of the energy gap.",
        "positive": "Stabilization of a linear nanomechanical oscillator to its ultimate\n  thermodynamic limit: The rapid development of micro- and nanooscillators in the past decade has\nled to the emergence of novel sensors that are opening new frontiers in both\napplied and fundamental science. The potential of these novel devices is,\nhowever, strongly limited by their increased sensitivity to external\nperturbations. We report a non-invasive optomechanical nano-stabilization\ntechnique and apply the method to stabilize a linear nanomechanical beam at its\nultimate thermodynamic limit at room temperature. The reported ability to\nstabilize a mechanical oscillator to the thermodynamic limit can be extended to\na variety of systems and increases the sensitivity range of nanosensors in both\nfundamental and applied studies."
    },
    {
        "anchor": "Anti-crossings of spin-split Landau levels in an InAs two-dimensional\n  electron gas with spin-orbit coupling: We report tilted-field transport measurements in the quantum-Hall regime in\nan InAs/In_0.75Ga_0.25As/In_0.75Al_0.25As quantum well. We observe\nanti-crossings of spin-split Landau levels, which suggest a mixing of spin\nstates at Landau level coincidence. We propose that the level repulsion is due\nto the presence of spin-orbit and of band-non-parabolicity terms which are\nrelevant in narrow-gap systems. Furthermore, electron-electron interaction is\nsignificant in our structure, as demonstrated by the large values of the\ninteraction-induced enhancement of the electronic g-factor.",
        "positive": "Roadmap for gallium arsenide spin qubits: Gate-defined quantum dots in gallium arsenide (GaAs) have been used\nextensively for pioneering spin qubit devices due to the relative simplicity of\nfabrication and favourable electronic properties such as a single conduction\nband valley, a small effective mass, and stable dopants. GaAs spin qubits are\nreadily produced in many labs and are currently studied for various\napplications, including entanglement, quantum non-demolition measurements,\nautomatic tuning, multi-dot arrays, coherent exchange coupling, and\nteleportation. Even while much attention is shifting to other materials, GaAs\ndevices will likely remain a workhorse for proof-of-concept quantum information\nprocessing and solid-state experiments."
    },
    {
        "anchor": "Intrinsic Rashba coupling due to Hydrogen bonding in DNA: We present an analytical model for the role of hydrogen bonding on the\nspin-orbit coupling of model DNA molecule. Here we analyze in detail the\nelectric fields due to the polarization of the Hydrogen bond on the DNA base\npairs and derive, within tight binding analytical band folding approach, an\nintrinsic Rashba coupling which should dictate the order of the spin active\neffects in the Chiral-Induced Spin Selectivity (CISS) effect. The coupling\nfound is ten times larger than the intrinsic coupling estimated previously and\npoints to the predominant role of hydrogen bonding in addition to chirality in\nthe case of biological molecules. We expect similar dominant effects in\noligopeptides, where the chiral structure is supported by hydrogen-bonding and\nbears on orbital carrying transport electrons.",
        "positive": "Spin-valley blockade in carbon nanotube double quantum dots: We present a theoretical study of the Pauli or spin-valley blockade for\ndouble quantum dots in semiconducting carbon nanotubes. In our model we take\ninto account the following characteristic features of carbon nanotubes: (i)\nfourfold (spin and valley) degeneracy of the quantum dot levels, (ii) the\nintrinsic spin-orbit interaction which is enhanced by the tube curvature, and\n(iii) valley-mixing due to short-range disorder, i.e., substitutional atoms,\nadatoms, etc. We find that the spin-valley blockade can be lifted in the\npresence of short-range disorder, which induces two independent random (in\nmagnitude and direction) valley-Zeeman-fields in the two dots, and hence acts\nsimilarly to hyperfine interaction in conventional semiconductor quantum dots.\nIn the case of strong spin-orbit interaction, we identify a parameter regime\nwhere the current as the function of an applied axial magnetic field shows a\nzero-field dip with a width controlled by the interdot tunneling amplitude, in\nagreement with recent experiments."
    },
    {
        "anchor": "Cavity sideband cooling of the Josephson phase: An extended Josephson junction intrinsically couples the superconducting\ncurrent to the microwave cavity in the insulating barrier. We demonstrate that\nthis coupling produces sidebands in the microwave cavity resonances of the\njunction. By measuring the switching current distribution, we show that\nmicrowave radiation at sidebands brings the Josephson phase out of equilibrium.\nIn particular, the effective phase temperature is reduced or enhanced through\nanti-Stokes and Stokes scattering, respectively. Phase cooling and heating both\nincrease with microwave power.",
        "positive": "Fractional quantum Hall effect of topological surface states under a\n  strong tilted magnetic field: The fractional quantum Hall effect (FQHE) of topological surface-state\nparticles under a tilted strong magnetic field is theoretically studied by\nusing the exact diagonalization method. The Haldane's pseudopotentials for the\nCoulomb interaction are analytically obtained. The results show that by\nincreasing the in-plane component of the tilted magnetic field, the FQHE state\nat $n$=0 Landau level (LL) becomes more stable, while the stabilities of\n$n$=$\\pm1$ LLs become weaker. Moreover, we find that the excitation gaps of the\n$\\nu=1/3$ FQHE states increase as the tilt angle is increased."
    },
    {
        "anchor": "Quantum electronic transport of topological surface states in beta-Ag2Se\n  nanowire: Single-crystalline \\beta-Ag2Se nanostructures, a new class of 3D topological\ninsulators (TIs), were synthesized using the chemical vapor transport method.\nThe topological surface states were verified by measuring electronic transport\nproperties including the weak antilocalization effect, Aharonov-Bohm\noscillations, and Shubnikov-de Haas oscillations. First-principles band\ncalculations revealed that the band inversion in \\b{eta}-Ag2Se is caused by\nstrong spin-orbit coupling and Ag-Se bonding hybridization. These extensive\ninvestigations provide new meaningful information about silver-chalcogenide TIs\nthat have anisotropic Dirac cones, which could be useful for spintronics\napplications.",
        "positive": "Anomalous excitations of atomically crafted quantum magnets: High energy resolution spectroscopic studies of quantum magnets have proven\nto be extremely valuable in directly accessing magnetodynamics quantities, such\nas energy barriers, magnetic interactions, lifetime of excited states and\nfluctuations at the most fundamental level. Here, we explore the existence of a\nnew flavor of low-energy spin-excitations for quantum spins coupled to an\nelectron bath. In sharp contrast to the usual tunneling signature of two steps\nsymmetrically centered around the Fermi level, we find a single step in the\nconductance. Combining time-dependent and many-body perturbation theories,\nmagnetic field-dependent tunneling spectra are explained to be the result of an\ninterplay between weak magnetic anisotropy energy, magnetic interactions and\nStoner-like electron-hole excitations that are strongly dependent on the\nmagnetic states of the studied nanostructures. We additionally map the\nevolution of the conductance peak in artificial nanostructures crafted\natom-by-atom, which show clear evidence of spin-coupled behavior. The results\nare rationalized in terms of a non-collinear magnetic ground state and the\ndominance of ferro- and antiferromagnetic interactions. The atomically crafted\nnanomagnets offer an appealing model for the exploration of electrically pumped\nspin systems."
    },
    {
        "anchor": "High-Q Gold and Silicon Nitride Bilayer Nanostrings: Low-mass, high-Q, silicon nitride nanostrings are at the cutting edge of\nnanomechanical devices for sensing applications. Here we show that the addition\nof a chemically functionalizable gold overlayer does not adversely affect the Q\nof the fundamental out-of-plane mode. Instead the device retains its mechanical\nresponsiveness while gaining sensitivity to molecular bonding. Furthermore,\ndifferences in thermal expansion within the bilayer give rise to internal\nstresses that can be electrically controlled. In particular, an alternating\ncurrent excites resonant motion of the nanostring. This AC thermoelastic\nactuation is simple, robust, and provides an integrated approach to sensor\nactuation.",
        "positive": "Probing electronic excitations in mono- to pentalayer graphene by\n  micro-magneto-Raman spectroscopy: We probe electronic excitations between Landau levels in freestanding\n$N-$layer graphene over a broad energy range, with unprecedented spectral and\nspatial resolution, using micro-magneto Raman scattering spectroscopy. A\ncharacteristic evolution of electronic bands in up to five Bernal-stacked\ngraphene layers is evidenced and shown to remarkably follow a simple\ntheoretical approach, based on an effective bilayer model. $(N>3)$-layer\ngraphene appear as appealing candidates in the quest for novel phenomena,\nparticularly in the quantum Hall effect regime. Our work paves the way towards\nminimally-invasive investigations of magneto-excitons in other emerging\nlow-dimensional systems, with a spatial resolution down to 1$~\\mu$m."
    },
    {
        "anchor": "Time-resolved diffraction and photoelectron spectroscopy investigation\n  of the reactive molecular beam epitaxy of $\\mathrm{Fe_3O_4}$ ultrathin films: We present time-resolved high energy x-ray diffraction (tr-HEXRD),\ntime-resolved hard x-ray photoelectron spectroscopy (tr-HAXPES) and\ntime-resolved grazing incidence small angle x-ray scattering (tr-GISAXS) data\nof the reactive molecular beam epitaxy (RMBE) of $\\mathrm{Fe_3O_4}$ ultrathin\nfilms on various substrates. Reciprocal space maps are recorded during the\ndeposition of $\\mathrm{Fe_3O_4}$ on $\\mathrm{SrTiO_3(001)}$, MgO(001) and\nNiO/MgO(001) in order to observe the temporal evolution of Bragg reflections\nsensitive to the octahedral and tetrahedral sublattices of the inverse spinel\nstructure of $\\mathrm{Fe_3O_4}$. A time delay between the appearance of rock\nsalt and spinel-exclusive reflections reveals that first, the iron oxide film\ngrows with $\\mathrm{Fe_{1-\\delta}O}$ rock salt structure with exclusive\noccupation of octahedral lattice sites. When this film is 1.1$\\,$nm thick, the\nfurther growth of the iron oxide film proceeds in the inverse spinel structure,\nwith both octahedral and tetrahedral lattice sites being occupied. In addition,\niron oxide on $\\mathrm{SrTiO_3(001)}$ initially grows with none of these\nstructures. Here, the formation of the rock salt structure starts when the film\nis 1.5$\\,$nm thick. This is confirmed by tr-HAXPES data obtained during growth\nof iron oxide on $\\mathrm{SrTiO_3(001)}$, which demonstrate an excess of\n$\\mathrm{Fe^{2+}}$ cations in growing films thinner than 3.2$\\,$nm. This rock\nsalt phase only appears during growth and vanishes after the supply of the Fe\nmolecular beam is stopped. Thus, it can be concluded the rock salt structure of\nthe interlayer is a property of the dynamic growth process. The tr-GISAXS data\nlink these structural results to an island growth mode of the first 2-3$\\,$nm\non both MgO(001) and $\\mathrm{SrTiO_3(001)}$ substrates.",
        "positive": "Spin-Noise and Damping in Individual Metallic Ferromagnetic\n  Nanoparticles: We introduce a highly sensitive and relatively simple technique to observe\nmagnetization motion in single Ni nanoparticles, based on charge sensing by\nelectron tunneling at millikelvin temperature. Sequential electron tunneling\nvia the nanoparticle drives nonequilibrium magnetization dynamics, which\ninduces an effective charge noise that we measure in real time. In the free\nspin diffusion regime, where the electrons and magnetization are in detailed\nbalance, we observe that magnetic damping time exhibits a peak with the\nmagnetic field, with a record long damping time of $\\simeq 10$~ms."
    },
    {
        "anchor": "Moir\u00e9 Fractional Chern Insulators II: First-principles Calculations\n  and Continuum Models of Rhombohedral Graphene Superlattices: The experimental discovery of fractional Chern insulators (FCIs) in\nrhombohedral pentalayer graphene twisted on hexagonal boron nitride (hBN) has\npreceded theoretical prediction. Supported by large-scale first principles\nrelaxation calculations at the experimental twist angle of $0.77^\\circ$, we\nobtain an accurate continuum model of $n=3,4,5,6,7$ layer rhombohedral\ngraphene-hBN moir\\'e systems. Focusing on the pentalayer case, we analytically\nexplain the robust $|C|=0,5$ Chern numbers seen in the low-energy\nsingle-particle bands and their flattening with displacement field, making use\nof a minimal two-flavor continuum Hamiltonian derived from the full model. We\nthen predict nonzero valley Chern numbers at the $\\nu = -4,0$ insulators\nobserved in experiment. Our analysis makes clear the importance of displacement\nfield and the moir\\'e potential in producing localized \"heavy fermion\" charge\ndensity in the top valence band, in addition to the nearly free conduction\nband. Lastly, we study doubly aligned devices as additional platforms for\nmoir\\'e FCIs with higher Chern number bands.",
        "positive": "Thermal Transport Signatures of Broken-Symmetry Phases in Graphene: In the half-filled zero-energy Landau level of bilayer graphene, competing\nphases with spontaneously broken symmetries and an intriguing quantum critical\nbehavior have been predicted. Here we investigate signatures of these\nbroken-symmetry phases in thermal transport measurements. To this end we\ncalculate the spectrum of spin and valley waves in the $\\nu=0$ quantum Hall\nstate of bilayer graphene. The presence of Goldstone modes enables heat\ntransport even at low temperatures, which can serve as compelling evidence for\nspontaneous symmetry breaking. By varying external electric and magnetic fields\nit is possible to determine the nature of the symmetry breaking and\ntemperature-dependent measurements may yield additional information about\ngapped modes."
    },
    {
        "anchor": "Spin transverse force and quantum transverse transport: We present a brief review on spin transverse force, which exerts on the spin\nas the electron is moving in an electric field. This force, analogue to the\nLorentz force on electron charge, is perpendicular to the electric field and\nspin current carried by the electron. The force stems from the spin-orbit\ncoupling of electrons as a relativistic quantum effect, and could be used to\nunderstand the Zitterbewegung of electron wave packet and the quantum\ntransverse transport of electron in a heuristic way.",
        "positive": "Helical quantum Hall Edge modes in bilayer graphene: a realization of\n  quantum spin-ladders: The rich phase diagram of quantum spin-ladder systems has attracted much\nattention in the theoretical literature. The progress in experimental\nrealisations of this fascinating physics however has been much slower. While\nmaterials with a ladder-like structure exist, one always has coupling between\nthe ladders to muddy the waters. In addition, such materials exhibit limited\n(if any) tunability in terms of the magnetic exchange parameters, and\nexperimental probing of the different phases is a great challenge. In this\nwork, we show that a realisation of spin-ladder physics can occur in an\nengineered nanostructure made out of bilayer graphene in the zero-filling\nquantum Hall state. Specifically, we describe a split-double-gated setup in\nwhich a domain wall is explicitly induced in the middle of the sample, and show\nthat an effective spin-ladder forms along this domain wall. The interaction\nstrengths of the ladder are tunable by adjusting magnetic and electric fields\nas well as the spacing between the gates. Furthermore, we demonstrate that the\neffective spin ladder has a helical nature, meaning that the spin-correlations\nmay be probed rather simply with charge transport experiments. We describe the\nphase diagram of this system, and show that certain transport measurements are\nvery sensitive to the phase."
    },
    {
        "anchor": "Hall effect for indirect excitons in an inhomogeneous magnetic field: We study the effect of non-homogeneous out-of-plane magnetic field on the\nbehaviour of 2D spatially indirect excitons. Due to the difference of magnetic\nfield acting on electrons and holes the total Lorentz force affecting the\ncenter of mass motion of an indirect exciton appears. Consequently, an indirect\nexciton acquires an effective charge proportional to the gradient of the\nmagnetic field. The appearance of the Lorentz force causes the Hall effect for\nneutral bosons which can be detected by measurement of the spatially\ninhomogeneous blueshift of the photoluminescence using counter-flow experiment.",
        "positive": "Depinning of the Charge-Density Waves in Quasi-2D 1T-TaS2 Devices\n  Operating at Room Temperature: We report on depinning of nearly-commensurate charge-density waves in 1T-TaS2\nthin-films at room temperature. A combination of the differential\ncurrent-voltage measurements with the low-frequency noise spectroscopy provide\nunambiguous means for detecting the depinning threshold field in quasi-2D\nmaterials. The depinning process in 1T-TaS2 is not accompanied by an observable\nabrupt increase in electric current - in striking contrast to depinning in the\nconventional charge-density-wave materials with quasi-1D crystal structure. We\nexplained it by the fact that the current density from the charge-density waves\nin the 1T-TaS2 devices is orders of magnitude smaller than the current density\nof the free carriers available in the discommensuration network surrounding the\ncommensurate charge-density-wave islands. The depinning fields in 1T-TaS2\nthin-film devices are several orders of magnitude larger than those in quasi-1D\nvan der Waals materials. Obtained results are important for the proposed\napplications of the charge-density-wave devices in electronics."
    },
    {
        "anchor": "Direct Dispersive Monitoring of Charge Parity in Offset-Charge-Sensitive\n  Transmons: A striking characteristic of superconducting circuits is that their\neigenspectra and intermode coupling strengths are well predicted by simple\nHamiltonians representing combinations of quantum circuit elements. Of\nparticular interest is the Cooper-pair-box Hamiltonian used to describe the\neigenspectra of transmon qubits, which can depend strongly on the offset-charge\ndifference across the Josephson element. Notably, this offset-charge dependence\ncan also be observed in the dispersive coupling between an ancillary readout\nmode and a transmon fabricated in the offset-charge-sensitive (OCS) regime. We\nutilize this effect to achieve direct, high-fidelity dispersive readout of the\njoint plasmon and charge-parity state of an OCS transmon, which enables\nefficient detection of charge fluctuations and nonequilibrium-quasiparticle\ndynamics. Specifically, we show that additional high-frequency filtering can\nextend the charge-parity lifetime of our device by two orders of magnitude,\nresulting in a significantly improved energy relaxation time\n$T_1\\sim200~\\mu\\mathrm{s}$.",
        "positive": "Quantum Dots and Etch-Induced Depletion of a Silicon 2DEG: The controlled depletion of electrons in semiconductors is the basis for\nnumerous devices. Reactive-ion etching provides an effective technique for\nfabricating both classical and quantum devices. However, Fermi level pinning\ncan occur, and must be carefully considered in the development of small\ndevices, such as quantum dots. Because of depletion, the electrical size of the\ndevice is reduced in comparison with its physical dimension. To investigate\nthis issue, we fabricate several types of devices in silicon-germanium\nheterostructures using two different etches, CF$_4$ and SF$_6$. We estimate the\ndepletion width associated with each etch by two methods: (i) conductance\nmeasurements in etched wires of decreasing thickness (to determine the onset of\ndepletion), (ii) capacitance measurements of quantum dots (to estimate the size\nof the active region). We find that the SF$_6$ etch causes a much smaller\ndepletion width, making it more suitable for device fabrication."
    },
    {
        "anchor": "Mesoscopic fluctuations of off-diagonal matrix elements of the angular\n  momentum and orbital magnetism of free electrons in a rectangular box: We study, analytically and numerically, mesoscopic fluctuations of the\noff-diagonal matrix elements of the orbital angular momentum between the\nnearest energy levels $i=(n_{x},n_{y}) $ and $f=(k_{x},k_{y}) $ in a\nrectangular box with incommensurate sides. In the semiclassical regime, where\nthe level number of $i$ is $\\cal{N}\\gg 1$, our derivation gives $\\left< |\n\\hat{L}_{if}| ^{2}\\right> \\sim \\sqrt{\\cal{N}}$. Numerical simulations, using\nsimultaneous ensemble averaging (over the aspect ratios of rectangles) and\nspectral averaging (over the energy interval), are in excellent agreement with\nthis analytical prediction. Physically, the mean is dominated by the level\npairs $k_{x}=n_{x}\\pm 1$, $k_{y}=n_{y}\\mp 1$. Also in a rectangular box, we\ninvestigate the mean orbital susceptibility of a free electron gas and argue\nthat it reduces, up to a coefficient, to the two-level van Vleck susceptibility\nthat involves the last occupied (Fermi) level $i$ and the first unoccupied\nlevel $f$. This result is confirmed numerically as well, albeit the effect of\nfluctuations is much more pronounced for the susceptibility since it is due\nboth to large fluctuations in $\\left< | \\hat{L}_{if}| ^{2}\\right>$ and in level\nseparations $\\epsilon_{f}-\\epsilon_{i}$ (level bunching).",
        "positive": "Temporal universal conductance fluctuations in RuO$_2$ nanowires due to\n  mobile defects: Temporal universal conductance fluctuations (TUCF) are observed in RuO$_2$\nnanowires at cryogenic temperatures. The fluctuations persist up to very high\n$T \\sim 10$ K. Their root-mean-square magnitudes increase with decreasing $T$,\nreaching $\\sim 0.2 e^2/h$ at $T \\lesssim 2$ K. These fluctuations are shown to\noriginate from scattering of conduction electrons with rich amounts of mobile\ndefects in artificially synthesized metal oxide nanowires. TUCF characteristics\nin both one-dimensional saturated and unsaturated regimes are identified and\nexplained in terms of current theories. Furthermore, the TUCF as a probe for\nthe characteristic time scales of the mobile defects (two-level systems) are\ndiscussed."
    },
    {
        "anchor": "Tunable skewed edges in puckered structures: We propose a new type of edges, arising due to the anisotropy inherent in the\npuckered structure of a honeycomb system such as in phosphorene. Skewed-zigzag\nand skewed-armchair nanoribbons are semiconducting and metallic, respectively,\nin contrast to their normal edge counterparts. Their band structures are\ntunable, and a metal-insulator transition is induced by an electric field. We\npredict a field-effect transistor based on the edge states in skewed-armchair\nnanoribbons, where the edge state is gapped by applying arbitrary small\nelectric field $E_z$. A topological argument is presented, revealing the\ncondition for the emergence of such edge states.",
        "positive": "Toward the creation of terahertz graphene injection laser: We study the effect of population inversion associated with the electron and\nhole injection in graphene p-i-n structures at the room and slightly lower\ntemperatures. It is assumed that the recombination and energy relaxation of\nelectrons and holes is associated primarily with the interband and intraband\nprocesses assisted by optical phonons. The dependences of the electron-hole and\noptical phonon effective temperatures on the applied voltage, the\ncurrent-voltage characteristics, and the frequency-dependent dynamic\nconductivity are calculated. In particular, we demonstrate that at low and\nmoderate voltages the injection can lead to a pronounced cooling of the\nelectron-hole plasma in the device i-section to the temperatures below the\nlattice temperature. However at higher voltages, the voltage dependences can be\nambiguous exhibiting the S-shape.\n  It is shown that the frequency-dependent dynamic conductivity can be negative\nin the terahertz range of freqiencies at certain values of the applied voltage.\nThe electron-hole plasma cooling substantially reinforces the effect of\nnegative dynamic conductivity and promotes the realization of terahertz lasing.\nOn the other hand, the heating of optical phonon system can also be crucial\naffecting the realization of negative dynamic conductivity and terahertz lasing\nat the room temperatures."
    },
    {
        "anchor": "Measurement of the current-phase relation of superconducting atomic\n  contacts: We have probed the current-phase relation of an atomic contact placed with a\ntunnel junction in a small superconducting loop. The measurements are in\nquantitative agreement with the predictions of a resistively shunted SQUID\nmodel in which the Josephson coupling of the contact is calculated using the\nindependently determined transmissions of its conduction channels.",
        "positive": "Predicted defect induced vortex core switching in thin magnetic\n  nanodisks: We investigate the influence of artificial defects (small holes) inserted\ninto magnetic nanodisks on the vortex core dynamics. One and two holes\n(antidots) are considered. In general, the core falls into the hole but, in\nparticular, we would like to remark an interesting phenomenon not yet observed,\nwhich is the vortex core switching induced by the vortex-hole interactions. It\noccurs for the case with only one hole and for very special conditions\ninvolving the hole size and position as well as the disk size. Any small\ndeformation in the disk geometry such as the presence of a second antidot\nchanges completely the vortex dynamics and the vortex core eventually falls\ninto one of the defects. After trapped, the vortex center still oscillates with\na very high frequency and small amplitude around the defect center."
    },
    {
        "anchor": "Spin Fluctuation Induced Linear Magnetoresistance in Ultrathin\n  Superconducting FeSe Films: The discovery of high-temperature superconductivity in FeSe/STO has trigged\ngreat research interest to reveal a range of exotic physical phenomena in this\nnovel material. Here we present a temperature dependent magnetotransport\nmeasurement for ultrathin FeSe/STO films with different thickness and\nprotection layers. Remarkably, a surprising linear magnetoresistance (LMR) is\nobserved around the superconducting transition temperatures but absent\notherwise. The experimental LMR can be reproduced by magnetotransport\ncalculations based on a model of magnetic field dependent disorder induced by\nspin fluctuation. Thus, the observed LMR in coexistence with superconductivity\nprovides the first magnetotransport signature for spin fluctuation around the\nsuperconducting transition region in ultrathin FeSe/STO films.",
        "positive": "Unsupervised machine learning and band topology: The study of topological bandstructures is an active area of research in\ncondensed matter physics and beyond. Here, we combine recent progress in this\nfield with developments in machine-learning, another rising topic of interest.\nSpecifically, we introduce an unsupervised machine-learning approach that\nsearches for and retrieves paths of adiabatic deformations between\nHamiltonians, thereby clustering them according to their topological\nproperties. The algorithm is general as it does not rely on a specific\nparameterization of the Hamiltonian and is readily applicable to any symmetry\nclass. We demonstrate the approach using several different models in both one\nand two spatial dimensions and for different symmetry classes with and without\ncrystalline symmetries. Accordingly, it is also shown how trivial and\ntopological phases can be diagnosed upon comparing with a generally designated\nset of trivial atomic insulators."
    },
    {
        "anchor": "Quantum theory of spin waves in finite chiral spin chains: We calculate the effect of spin waves on the properties of finite size spin\nchains with a chiral spin ground state observed on bi-atomic Fe chains\ndeposited on Iridium(001). The system is described with a Heisenberg model\nsupplemented with a Dzyaloshinskii-Moriya (DM) coupling and a uniaxial single\nion anisotropy that presents a chiral spin ground state. Spin waves are studied\nusing the Holstein-Primakoff (HP) boson representation of spin operators. Both\nthe renormalized ground state and the elementary excitations are found by means\nof Bogoliubov transformation, as a function of the two variables that can be\ncontrolled experimentally, the applied magnetic field and the chain length.\nThree main results are found. First, because of the non-collinear nature of the\nclassical ground state, there is a significant zero point reduction of the\nground state magnetization of the spin spiral. Second, the two lowest energy\nspin waves are edge modes in the spin spiral state that, above a critical field\nthe results into a collinear ferromagnetic ground state, become confined bulk\nmodes. Third, in the spin spiral state, the spin wave spectrum exhibits\noscillatory behavior as function of the chain length with the same period of\nthe spin helix.",
        "positive": "Nanoscale NMR Spectroscopy using Self-Calibrating Nanodiamond Quantum\n  Sensors: Conventional nuclear magnetic resonance (NMR) spectroscopy relies on\nacquiring signal from a macroscopic ensemble of molecules to gain information\nabout molecular structure and dynamics. Transferring this technique to\nnanoscale sample sizes would enable molecular analysis without the effects of\naveraging over spatial and temporal inhomogeneities and without the need for\nmacroscopic volumes of analyte, both inherent to large ensemble measurements.\nNanoscale NMR based on nitrogen vacancy (NV) centers inside bulk diamond chips\nachieves single nuclear spin sensitivity and the resolution required to\ndetermine chemical structure, but their detection volume is limited to a few\nnanometers above the diamond surface for the most sensitive devices. This\nprecludes them from use for nuclear spin sensing with nanoscale resolution\ninside thicker structures, such as cells. Here, we demonstrate the detection of\nNMR signals from multiple nuclear species in a (19 nm)3 volume using versatile\nNV-NMR devices inside nanodiamonds that have a typical 30 nm diameter. The\ndevices detect a signal generated by a small number of analyte molecules on the\norder of 1000. To use these devices in situ, the detected signal must be\ncorrected for the unknown geometry of each nanodiamond device. We show that\nsuch a calibration could be performed by exploiting the signal from a thin\nlayer of nuclei on the diamond surface. These results, combined with the low\ntoxicity of nanodiamonds and their amenability to surface functionalization,\nindicate that nanodiamond NV-NMR devices could become a useful tool for\nnanoscale NMR-based sensing inside living cells."
    },
    {
        "anchor": "Laser-induced topological transitions in phosphorene with inversion\n  symmetry: Recent ab initio calculations and experiments reported\ninsulating-semimetallic phase transitions in multilayer phosphorene under a\nperpendicular dc field, pressure or doping, as a possible route to realize\ntopological phases. In this work, we show that even a monolayer phosphorene may\nundergo Lifshitz transitions toward semimetallic and topological insulating\nphases, provided it is rapidly driven by in-plane time-periodic laser fields.\nBased on a four-orbital tight-binding description, we give an\ninversion-symmetry-based prescription in order to apprehend the topology of the\nphoton-renormalized band structure, up to the second order in the\nhigh-frequency limit. Apart from the initial band insulating behavior, two\nadditional phases are thus identified. A semimetallic phase with massless Dirac\nelectrons may be induced by linear polarized fields, whereas elliptic polarized\nfields are likely to drive the material into an anomalous quantum Hall phase.",
        "positive": "Optical-power-dependent splitting of magnetic resonance in\n  nitrogen-vacancy centers in diamond: Nitrogen-vacancy (NV) centers in diamonds are a powerful tool for accurate\nmagnetic field measurements. The key is precisely estimating the\nfield-dependent splitting width of the optically detected magnetic resonance\n(ODMR) spectra of the NV centers. In this study, we investigate the optical\npower dependence of the ODMR spectra using NV ensemble in nanodiamonds (NDs)\nand a single-crystal bulk diamond. We find that the splitting width\nexponentially decays and is saturated as the optical power increases.\nComparison between NDs and a bulk sample shows that while the decay amplitude\nis sample-dependent, the optical power at which the decay saturates is almost\nsample-independent. We propose that this unexpected phenomenon is an intrinsic\nproperty of the NV center due to non-axisymmetry deformation or impurities. Our\nfinding indicates that diamonds with less deformation are advantageous for\naccurate magnetic field measurements."
    },
    {
        "anchor": "Free carrier absorption in cascade structures due to static scatterers\n  in the in-plane polarization: We report on the computation of the free carrier absorption induced by static\nscatterers in cascade structures when the electromagnetic wave propagates along\nthe growth axis. We find that a Drude-like tail exists for this polarization.\nThe absorption is found larger than when the wave propagates in the layer\nplane. Also intra-subband scattering is found more efficient than inter-subband\nscattering. The alloy scattering is found to be particularly efficient.",
        "positive": "Berry Phase in a Single Quantum Dot with Spin-Orbit Interaction: Berry phase in a single quantum dot with Rashba spin-orbit coupling is\ninvestigated theoretically. Berry phases as functions of magnetic field\nstrength, dot size, spin-orbit coupling and photon-spin coupling constants are\nevaluated. It is shown that the Berry phase will alter dramatically from 0 to\n$2\\pi$ as the magnetic field strength increases. The threshold of magnetic\nfield depends on the dot size and the spin-orbit coupling constant."
    },
    {
        "anchor": "Topological phases of quantized light: Topological photonics is an emerging research area that focuses on the\ntopological states of classical light. Here we reveal the topological phases\nthat are intrinsic to the particle nature of light, i.e., solely related to the\nquantized Fock states and the inhomogeneous coupling between them. The\nHamiltonian of two cavities coupled with a two-level atom is an intrinsic\none-dimensional Su-Schriefer-Heeger model of Fock states. By adding another\ncavity, the Fock-state lattice is extended to two dimensions with a honeycomb\nstructure, where the strain due to the inhomogeneity of the coupling strengths\ninduces a Lifshitz topological phase transition between a semimetal and a band\ninsulator. In the semimetallic phase, the strain is equivalent to a\npseudomagnetic field, which results in the quantization of the Landau levels\nand the valley Hall effect. We further construct a Haldane model where the\ntopological phases can be characterized by the topological markers. This study\ndemonstrates a fundamental distinction between the topological phases of bosons\nand fermions and provides a novel platform for studying topological physics in\ndimensions higher than three.",
        "positive": "Tuning the valley and chiral quantum state of Dirac electrons in van der\n  Waals heterostructures: Chirality is a fundamental property of electrons with the relativistic\nspectrum found in graphene and topological insulators. It plays a crucial role\nin relativistic phenomena, such as Klein tunneling, but it is difficult to\nvisualize directly. Here we report the direct observation and manipulation of\nchirality and pseudospin polarization in the tunneling of electrons between two\nalmost perfectly aligned graphene crystals. We use a strong in-plane magnetic\nfield as a tool to resolve the contributions of the chiral electronic states\nthat have a phase difference between the two components of their vector\nwavefunction. Our experiments not only shed light on chirality, but also\ndemonstrate a technique for preparing graphene's Dirac electrons in a\nparticular quantum chiral state in a selected valley."
    },
    {
        "anchor": "Path integral simulation of exchange interactions in CMOS spin qubits: The boom of semiconductor quantum computing platforms created a demand for\ncomputer-aided design and fabrication of quantum devices. Path integral Monte\nCarlo (PIMC) can have an important role in this effort because it intrinsically\nintegrates strong quantum correlations that often appear in these\nmulti-electron systems. In this paper we present a PIMC algorithm that\nestimates exchange interactions of three-dimensional electrically defined\nquantum dots. We apply this model to silicon metal-oxide-semiconductor (MOS)\ndevices and we benchmark our method against well-tested full configuration\ninteraction (FCI) simulations. As an application, we study the impact of a\nsingle charge trap on two exchanging dots, opening the possibility of using\nthis code to test the tolerance to disorder of CMOS devices. This algorithm\nprovides an accurate description of this system, setting up an initial step to\nintegrate PIMC algorithms into development of semiconductor quantum computers.",
        "positive": "Tuning of few-electron states and optical absorption anisotropy in GaAs\n  quantum rings: The electronic and optical properties of a GaAs quantum ring (QR) with few\nelectrons in the presence of the Rashba spin-orbit interaction (RSOI) and the\nDresselhaus spin-orbit interaction (DSOI) have been investigated theoretically.\nConfiguration interaction (CI) method is employed to calculate the eigenvalues\nand eigenstates of the multiple-electron QR accurately. Our numerical results\ndemonstrate that the symmetry breaking induced by the RSOI and DSOI leads to an\nanisotropic distribution of multi-electron states. The Coulomb interaction\noffers additional modulation of the electron distribution and thus the optical\nabsorption indices in the quantum rings. By tuning the magnetic/electric fields\nand/or electron numbers in a quantum ring, one can change its optical property\nsignificantly. Our theory provides a new way to control multi-electron states\nand optical properties of QR by hybrid modulations or by electrical means only."
    },
    {
        "anchor": "Majorana Kramers pairs in higher-order topological insulators: We propose a tune-free scheme to realize Kramers pairs of Majorana bound\nstates in recently discovered higher-order topological insulators (HOTIs). We\nshow that, by bringing two hinges of a HOTI into the proximity of an $s$-wave\nsuperconductor, the competition between local and crossed-Andreev pairing leads\nto the formation of Majorana Kramers pairs, when the latter pairing dominates\nover the former. We demonstrate that such a topological superconductivity is\nstabilized by moderate electron-electron interactions. The proposed setup\navoids the application of a magnetic field or local voltage gates, and requires\nweaker interactions compared with nonhelical nanowires.",
        "positive": "The $\u03b8$ vacuum reveals itself as the fundamental theory of the\n  quantum Hall effect. I. Confronting controversies: The $\\theta$ dependence of the Grassmannian $U(m+n)/U(m)\\times U(n)$\nnon-linear $\\sigma$ model is reexamined. This general theory provides an\nimportant laboratory for studying the quantum Hall effect, in the special limit\n$m=n=0$ (replica limit). We discover however that the quantum Hall effect is in\nfact independent of this limit and exists as a generic topological feature of\nthe theory for all non-negative values of $m$ and $n$. The results are in\nconcflict with many of the historical ideas and expectations on the basis of\nthe large $N$ expansion of the $CP^{N-1}$ or $SU(N)/U(N-1)$ model"
    },
    {
        "anchor": "Planar Hall effect with sixfold oscillations in a Dirac antiperovskite: The planar Hall effect (PHE), wherein a rotating magnetic field in the plane\nof a sample induces oscillating transverse voltage, has recently garnered\nattention in a wide range of topological metals and insulators. The observed\ntwofold oscillations in $\\rho_{yx}$ as the magnetic field completes one\nrotation are the result of chiral, orbital and/or spin effects. The\nantiperovskites $A_3B$O ($A$ = Ca, Sr, Ba; $B$ = Sn, Pb) are topological\ncrystalline insulators whose low-energy excitations are described by a\ngeneralized Dirac equation for fermions with total angular momentum $J = 3/2$.\nWe report unusual sixfold oscillations in the PHE of Sr$_3$SnO, which persisted\nnearly up to room temperature. Multiple harmonics (twofold, fourfold and\nsixfold), which exhibited distinct field and temperature dependencies, were\ndetected in $\\rho_{xx}$ and $\\rho_{yx}$. These observations are more diverse\nthan those in other Dirac and Weyl semimetals and point to a richer interplay\nof microscopic processes underlying the PHE in the antiperovskites.",
        "positive": "Microwave-induced conductance replicas in hybrid Josephson junctions\n  without Floquet-Andreev states: Light-matter interaction enables engineering of non-equilibrium quantum\nsystems. In condensed matter, spatially and temporally cyclic Hamiltonians are\nexpected to generate energy-periodic Floquet states, with properties\ninaccessible at thermal equilibrium. A recent work explored the tunnelling\nconductance of a planar Josephson junction under microwave irradiation, and\ninterpreted replicas of conductance features as evidence of steady\nFloquet-Andreev states. Here we realise a similar device in a hybrid\nsuperconducting-semiconducting heterostructure, which utilises a tunnelling\nprobe with gate-tunable transparency and allows simultaneous measurements of\nAndreev spectrum and current-phase relation of the planar Josephson junction.\nWe show that, in our devices, spectral replicas in sub-gap conductance emerging\nunder microwave irradiation are caused by photon assisted tunnelling of\nelectrons into Andreev states. The current-phase relation under microwave\nirradiation is also explained by the interaction of Andreev states with\nmicrowave photons, without the need to invoke Floquet states. The techniques\noutlined in this study establish a baseline to distinguish photon assisted\ntunnelling from Floquet-Andreev states in mesoscopic devices, a crucial\ndevelopment towards understanding light-matter coupling in hybrid\nnanostructures."
    },
    {
        "anchor": "Edge states in graphene-like systems: The edges of graphene and graphene like systems can host localized states\nwith evanescent wave function with properties radically different from those of\nthe Dirac electrons in bulk. This happens in a variety of situations, that are\nreviewed here. First, zigzag edges host a set of localized non dispersive state\nat the Dirac energy. At half filling, it is expected that these states are\nprone to ferromagnetic instability, causing a very interesting type of edge\nferromagnetism. Second, graphene under the influence of external perturbations\ncan host a variety of topological insulating phases, including the conventional\nQuantum Hall effect, the Quantum Anomalous Hall (QAH) and the Quantum Spin Hall\nphase, in all of which phases conduction can only take place through\ntopologically protected edge states. Here we provide an unified vision of the\nproperties of all these edge states, examined under the light of the same one\norbital tight-binding model. We consider the combined action of interactions,\nspin orbit coupling and magnetic field, which produces a wealth of different\nphysical phenomena. We briefly address what has been actually observed\nexperimentally.",
        "positive": "Localized States at Zigzag Edges of Multilayer Graphene and Graphite\n  Steps: We report the existence of zero energy surface states localized at zigzag\nedges of $N$-layer graphene. Working within the tight-binding approximation,\nand using the simplest nearest-neighbor model, we derive the analytic solution\nfor the wavefunctions of these peculiar surface states. It is shown that zero\nenergy edge states in multilayer graphene can be divided into three families:\n(i) states living only on a single plane, equivalent to surface states in\nmonolayer graphene; (ii) states with finite amplitude over the two last, or the\ntwo first layers of the stack, equivalent to surface states in bilayer\ngraphene; (iii) states with finite amplitude over three consecutive layers.\nMultilayer graphene edge states are shown to be robust to the inclusion of the\nnext nearest-neighbor interlayer hopping. We generalize the edge state solution\nto the case of graphite steps with zigzag edges, and show that edge states\nmeasured through scanning tunneling microscopy and spectroscopy of graphite\nsteps belong to family (i) or (ii) mentioned above, depending on the way the\ntop layer is cut."
    },
    {
        "anchor": "Modeling of electric double layer at solid-liquid interface with spatial\n  complexity: Electrical double layer (EDL) is formed when an electrode is in contact with\nan electrolyte solution, and is widely used in biophysics, electrochemistry,\npolymer solution and energy storage. Poisson-Boltzmann (PB) coupled equations\nprovides the foundational framework for modeling electrical potential and\ncharge distribution at EDL. In this work, based on fractional calculus, we\nreformulate the PB equations (with and without steric effects) by introducing a\nphenomenal parameter $D$ (with a value between 0 and 1) to account for the\nspatial complexity due to impurities in EDL. The electrical potential and ion\ncharge distribution for different $D$ are investigated. At $D$ = 1, the model\nrecover the classical findings of ideal EDL. The electrical potential decays\nslowly at $D <$1, thus suggesting a wider region of saturated layer under fixed\nsurface potential in the presence of spatial complexity. The fractional-space\ngeneralized model developed here provides a useful tool to account for spatial\ncomplexity effects which are not captured in the classic full-dimensional\nmodels.",
        "positive": "Spin transport in high-mobility graphene on WS$_2$ substrate with\n  electric-field tunable proximity spin-orbit interaction: Graphene supported on a transition metal dichalcogenide substrate offers a\nnovel platform to study the spin transport in graphene in presence of a\nsubstrate induced spin-orbit coupling, while preserving its intrinsic charge\ntransport properties. We report the first non-local spin transport measurements\nin graphene completely supported on a 3.5 nm thick tungsten disulfide (WS$_2$)\nsubstrate, and encapsulated from the top with a 8 nm thick hexagonal boron\nnitride layer. For graphene, having mobility up to 16,000\ncm$^2$V$^{-1}$s$^{-1}$, we measure almost constant spin-signals both in\nelectron and hole-doped regimes, independent of the conducting state of the\nunderlying WS$_2$ substrate, which rules out the role of spin-absorption by\nWS$_2$. The spin-relaxation time $\\tau_{\\text{s}}$ for the electrons in\ngraphene-on-WS$_2$ is drastically reduced down to~10 ps than $\\tau_{\\text{s}}$\n~ 800 ps in graphene-on-SiO$_2$ on the same chip. The strong suppression of\n$\\tau_{\\text{s}}$ along with a detectable weak anti-localization signature in\nthe quantum magneto-resistance measurements is a clear effect of the WS$_2$\ninduced spin-orbit coupling (SOC) in graphene. Via the top-gate voltage\napplication in the encapsulated region, we modulate the electric field by 1\nV/nm, changing $\\tau_{\\text{s}}$ almost by a factor of four which suggests the\nelectric-field control of the in-plane Rashba SOC. Further, via carrier-density\ndependence of $\\tau_{\\text{s}}$ we also identify the fingerprints of the\nD'yakonov-Perel' type mechanism in the hole-doped regime at the graphene-WS$_2$\ninterface."
    },
    {
        "anchor": "Charge density mapping of strongly-correlated few-electron\n  two-dimensional quantum dots by scanning probe technique: We perform a numerical simulation of mapping of charge confined in quantum\ndots by the scanning probe technique. We solve the few-electron Schr\\\"odinger\nequation with the exact diagonalization approach and evaluate the energy maps\nin function of the probe position. Next, from the energy maps we try to\nreproduce the charge density distribution using an integral equation given by\nthe perturbation theory. The reproduced density maps are confronted with the\noriginal ones. The present study covers two-dimensional quantum dots of various\ngeometries and profiles with the one-dimensional (1D) quantum dot as a limit\ncase. We concentrate on large quantum dots for which strong electron-electron\ncorrelations appear. For circular dots the correlations lead to formation of\nWigner molecules that in the presence of the tip appear in the laboratory\nframe. The unperturbed rotationally-symmetric charge density is surprisingly\nwell reproduced by the mapping. We find in general that the size of the\nconfined droplet as well as the spatial extent of the charge density maxima is\nunderestimated for repulsive tip potential and overestimated for the attractive\ntip. In lower-symmetry quantum dots the Wigner molecules with single-electron\nislands nucleate for some electron numbers even in the absence of the tip.\nThese charge densities are well resolved by the mapping. The single-electron\nislands appear in the laboratory frame provided that classical point charge\ndensity distribution is unique, in the 1D limit of confinement in particular.\nWe demonstrate that for electron systems which possess a few equivalent\nclassical configurations the repulsive probe switches between the\nconfigurations. In consequence the charge density evades mapping by the\nrepulsive probe.",
        "positive": "Anisotropic conductivity of disordered 2DEGs due to spin-orbit\n  interactions: We show that the conductivity tensor of a disordered two-dimensional electron\ngas becomes anisotropic in the presence of both Rashba and Dresselhaus\nspin-orbit interactions (SOI). This anisotropy is a mesoscopic effect and\nvanishes with vanishing charge dephasing time. Using a diagrammatic approach\nincluding zero, one, and two-loop diagrams, we show that a consistent\ncalculation needs to go beyond a Boltzmann equation approach. In the absence of\ncharge dephasing and for zero frequency, a finite anisotropy \\sigma_{xy}\ne^2/lhpf arises even for infinitesimal SOI."
    },
    {
        "anchor": "Few-electron liquid and solid phases in artificial molecules at high\n  magnetic field: Coupled semiconductor quantum dots form artificial molecules where relevant\nenergy scales controlling the interacting ground state can be easily tuned. By\napplying an external magnetic field it is possible to drive the system from a\nweak to a strong correlation regime where eventually electrons localize in\nspace in an ordered manner reminiscent of the two-dimensional Wigner crystal.\nWe explore the phase diagram of such \"Wigner molecules\" analyzing the angular\ncorrelation function obtained by the Configuration Interaction solution of the\nfull interacting Hamiltonian. Focus is on the role of tunneling in stabilizing\ndifferent ground states.",
        "positive": "Enhancement of Chiral-Induced Spin Selectivity via Circularly Polarized\n  Light: The notion of chiral-induced spin selectivity (CISS) has attracted intensive\nresearch interest recently. However, the practical applications of the CISS\neffects face challenges due to relatively low spin polarization. In this\nLetter, we propose a non-perturbative theory illustrating how circularly\npolarized (CP) light enhances CISS effects through strong light-matter\ninteractions. We introduce a Floquet electronic friction model to study the\nnonadiabatic dynamics and spin transport through a chiral molecule in a\nmolecule junction subjected to external driving. Our results show that the\ninterplay of the nonadiabatic effects and light-matter interactions can\nsignificantly ($>90\\%$) enhance electron spin polarization under CP light. Our\npredictions can be very useful in experiments for using CP light to control\nspin current in chiral molecular junctions."
    },
    {
        "anchor": "Local modified Becke-Johnson exchange-correlation potential for\n  interfaces, surfaces, and two-dimensional materials: The modified Becke-Johnson meta-GGA potential of density functional theory\nhas been shown to be the best exchange-correlation potential to determine band\ngaps of crystalline solids. However, it cannot be consistently used for the\nelectronic structure of non-periodic or nanostructured systems. We propose an\nextension of this potential that enables its use to study heterogeneous, finite\nand low-dimensional systems. This is achieved by using a coordinate-dependent\nexpression for the parameter $c$ that weights the Becke-Russel exchange, in\ncontrast to the original global formulation, where $c$ is just a fitted number.\nOur potential takes advantage of the excellent description of band gaps\nprovided by the modified Becke-Johnson potential and preserves its modest\ncomputational effort. Furthermore, it yields with one single calculation band\ndiagrams and band offsets of heterostructures and surfaces. We exemplify the\nusefulness and efficiency of our local meta-GGA potential by testing it for a\nseries of interfaces (Si/SiO$_2$, AlAs/GaAs, AlP/GaP, and GaP/Si), a Si\nsurface, and boron nitride monolayer.",
        "positive": "Thermal control across a chain of electronic nanocavities: We study a chain of alternating hot and cold electronic nanocavities --\nconnected to one another via resonant-tunneling quantum dots -- with the intent\nof achieving precise thermal control across the chain. This is accomplished by\npositioning the dots' energy levels such that a predetermined distribution of\nheat currents is realized across the chain in the steady state. The number of\nelectrons in each cavity is conserved in the steady state which constrains the\ncavities' chemical potentials. We determine these chemical potentials\nanalytically in the linear response regime where the energy differences between\nthe dots' resonant levels and the neighboring chemical potentials are much\nsmaller than the thermal energy. In this regime, the thermal control problem\ncan be solved exactly, while, in the general case, thermal control can only be\nachieved in a relative sense, that is, when one only preassigns the ratios\nbetween different heat currents. We apply our results to two different cases:\nWe first demonstrate that a \"heat switch\" can be easily realized with three\ncoupled cavities, then we show that our linear response results can provide\naccurate results in situations with a large number of cavities."
    },
    {
        "anchor": "Growth of monolayer graphene on 8deg off-axis 4H-SiC (000-1) substrates\n  with application to quantum transport devices: Using high temperature annealing conditions with a graphite cap covering the\nC-face of an 8deg off-axis 4H-SiC sample, large and homogeneous single\nepitaxial graphene layers have been grown. Raman spectroscopy shows evidence of\nthe almost free-standing character of these monolayer graphene sheets, which\nwas confirmed by magneto-transport measurements. We find a moderate p-type\ndoping, high carrier mobility and half integer Quantum Hall effect typical of\nhigh quality graphene samples. This opens the way to a fully compatible\nintegration of graphene with SiC devices on the wafers that constitute the\nstandard in today's SiC industry.",
        "positive": "Friction Fluctuations of Gold Nanoparticles in the Superlubric Regime: Superlubricity, or alternatively termed structural (super)lubrictiy, is a\nconcept where ultra-low friction is expected at the interface between sliding\nsurfaces if these surfaces are incommensurate and thus unable to interlock. In\nthis work, we now report on sudden, reversible, friction changes that have been\nobserved during AFM based nanomanipulation experiments of gold nanoparticles\nsliding on highly oriented pyrolythic graphite. These effects are can be\nexplained by rotations of the gold nanoparticles within the concept of\nstructural superlubricity, where the occurrence of ultra-low friction can\ndepend extremely sensitively on the relative orientation between the slider and\nthe substrate. From our theoretical simulations it will become apparent how\neven miniscule magnitudes of rotation are compatible to the observed effects\nand how size and shape of the particles can influence the dependence between\nfriction and relative orientation."
    },
    {
        "anchor": "Resonant reflection of interacting electrons from an impurity in a\n  quantum wire: interplay of Zeeman and spin-orbit effects: A single-channel quantum wire with two well-separated Zeeman subbands and in\nthe presence of a weak spin-orbit coupling is considered. An impurity level\nwhich is split off the upper subband is degenerate with the continuum of the\nlower subband. We show that, when the Fermi level lies in the vicinity of the\nimpurity level, the transport is completely blocked. This is the manifestation\nof the effect of resonant reflection and can be viewed as resonant tunneling\nbetween left-moving and right-moving electrons via the impurity level. We\nincorporate electron-electron interactions and study their effect on the shape\nof the resonant-reflection profile. This profile becomes a two-peak structure,\nwhere one peak is caused by resonant reflection itself, while the origin of the\nother peak is reflection from the Friedel oscillations of the electron density\nsurrounding the impurity.",
        "positive": "Hybrid magnetization dynamics in\n  $\\text{Cu}_\\text{2}\\text{OSeO}_\\text{3}$/$\\mathrm{NiFe}$ heterostructures: We investigate the coupled magnetization dynamics in heterostructures of a\nsingle crystal of the chiral magnet $\\mathrm{Cu_2OSeO_3}$ (CSO) and a\npolycrystalline ferromagnet $\\mathrm{NiFe}$ (Py) thin film using broadband\nferromagnetic resonance (FMR) at cryogenic temperatures. We observe the\nexcitation of a hybrid mode (HM) below the helimagnetic transition temperature\nof CSO. This HM is attributed to the spin dynamics at the CSO/Py interface. We\nstudy the HM by measuring its resonance frequencies for in plane rotations of\nthe external magnetic field. We find that the HM exhibits dominantly four-fold\nanisotropy, in contrast to the FMR of CSO and Py."
    },
    {
        "anchor": "Variations of vibronic states in densely-packed structures of molecules\n  with intramolecular dipoles: Electrostatic potentials strongly affect molecular energy levels and charge\nstates, providing the fascinating opportunity of molecular gating. Their\ninfluence on molecular vibrations remains less explored. Here, we investigate\nEthyl-Diaminodicyanoquinone molecules on a monolayer of MoS$_2$ on Au(111)\nusing scanning tunneling and atomic force microscopy and spectroscopy. These\nmolecules exhibit a large dipole moment in gas phase, which we find to\n(partially) persist on the MoS$_2$ monolayer. The self-assembled structures\nconsist of chains, where the dipoles of neighboring molecules are aligned\nanti-parallel. Thanks to the decoupling efficiency of the molecular states from\nthe metal by the MoS$_2$ interlayer, we resolve vibronic states of the\nmolecules, which vary in intensity depending on the molecular surrounding. We\nsuggest that the vibrations are strongly damped by electrostatic interactions\nwith the environment.",
        "positive": "Compact Localized States in Electric Circuit Flatband Lattices: We generate compact localized states in an electrical diamond lattice,\ncomprised of only capacitors and inductors, via local driving near its flatband\nfrequency. We compare experimental results to numerical simulations and find\nvery good agreement. We also examine the stub lattice, which features a\nflatband of a different class where neighboring compact localized states share\nlattice sites. We find that local driving, while exciting the lattice at that\nflatband frequency, is unable to isolate a single compact localized state due\nto their non-orthogonality. Finally, we introduce lattice nonlinearity and\nshowcase the realization of nonlinear compact localized states in the diamond\nlattice. Our findings pave the way of applying flatband physics to complex\nelectric circuit dynamics."
    },
    {
        "anchor": "Electrostatic confinement of electrons in an integrable graphene quantum\n  dot: We compare the conductance of an undoped graphene sheet with a small region\nsubject to an electrostatic gate potential for the cases that the dynamics in\nthe gated region is regular (disc-shaped region) and classically chaotic\n(stadium). For the disc, we find sharp resonances that narrow upon reducing the\narea fraction of the gated region. We relate this observation to the existence\nof confined electronic states. For the stadium, the conductance looses its\ndependence on the gate voltage upon reducing the area fraction of the gated\nregion, which signals the lack of confinement of Dirac quasiparticles in a\ngated region with chaotic classical electron dynamics.",
        "positive": "Universal Features of Spin Transport and Breaking of Unitary Symmetries: When time-reversal symmetry is broken, quantum coherent systems with and\nwithout spin rotational symmetry exhibit the same universal behavior in their\nelectric transport properties. We show that spin transport discriminates\nbetween these two cases. In systems with large charge conductance, spin\ntransport is essentially insensitive to the breaking of time-reversal symmetry.\nHowever, in the opposite limit of a single exit channel, spin currents vanish\nidentically in the presence of time-reversal symmetry, but are turned on by\nbreaking it with an orbital magnetic field."
    },
    {
        "anchor": "Study Of Organic Monolayer Modified Metal Oxide Semiconductor Devices\n  For High Temperature Applications: We report fabrication and characteristics of an organic monolayer based Metal\nOxide Semiconductor (MOS) device. In place of SiO2 oxide layer in the MOS\nconfiguration, we used 1H, 1H, 2H, 2H- perfluorooctyl trichlorosilane (FOTS)\nself-assembled monolayer as a substitution. The MOS device was fabricated by\nsimple steps like sputter deposition and dip coating method. The device was\nheat treated to different temperatures to understand its performance and\nefficiency for high temperature application. The MOS device was heated to\n150{\\deg} C, 350{\\deg}C and 550{\\deg}C and the energy band gap was found to be\nvaried in the order 2.5 eV, 3.0 eV and 3.4eV respectively. For non-heated\nsample, the energy band gap is 3.4 eV. The results shows that the parameters\nlike charge mobility ({\\mu}), energy band gap, and resistance were found to be\ndecreased after the heat treatment. The change in the energy band gap due to\nheat treatment has significantly influenced the I-V and the impedance\ncharacteristics. We observed that the MOS device started to conduct between 1V\nto 3V, further the device conduct till 20V. Impedance analysis show that device\nheated to 350 {\\deg}C shows the low impedance but the impedance starts to\nincrease for further heating up to 550{\\deg}C. Using Multi Dielectric Energy\nBand Diagram Program (MEBDP) we studied the MOS structure and C-V\ncharacteristics and temperature dependent behavior of the devices from 100K to\n600K. Our experimental work and simulation studies confirm that the FOTS SAM\nsubstituted MOS device could be used for high temperature applications. The\nexperimental observations are well supported by the simulation results. This\nstudy shows that the FOTS organic monolayer are promising substitute for SiO2\noxide layer in the MOS and MOSFET which could be used high temperature\napplications.",
        "positive": "Edge currents shunt the insulating bulk in gapped graphene: An energy gap can be opened in the electronic spectrum of graphene by lifting\nits sublattice symmetry. In bilayers, it is possible to open gaps as large as\n0.2 eV. However, these gaps rarely lead to a highly insulating state expected\nfor such semiconductors at low temperatures. This long-standing puzzle is\nusually explained by charge inhomogeneity. Here we investigate spatial\ndistributions of proximity-induced superconducting currents in gapped graphene\nand, also, compare measurements in the Hall bar and Corbino geometries in the\nnormal state. By gradually opening the gap in bilayer graphene, we find that\nthe supercurrent at the charge neutrality point changes from uniform to such\nthat it propagates along narrow stripes near graphene edges. Similar stripes\nare found in gapped monolayers. These observations are corroborated by using\nthe \"edgeless\" Corbino geometry in which case resistivity at the neutrality\npoint increases exponentially with increasing the gap, as expected for an\nordinary semiconductor. This is in contrast to the Hall bar geometry where\nresistivity measured under similar conditions saturates to values of only about\na few resistance quanta. We attribute the metallic-like edge conductance to a\nnontrivial topology of gapped Dirac spectra."
    },
    {
        "anchor": "Tuning resonance energy transfer with magneto-optical properties of\n  graphene: We investigate the resonance energy transfer (RET) rate between two quantum\nemitters near a suspended graphene sheet in vacuum under the influence of an\nexternal magnetic field. We perform the analysis for low and room temperatures\nand show that, due to the extraordinary magneto-optical response of graphene,\nit allows for an active control and tunability of the RET even in the case of\nroom temperature. We also demonstrate that the RET rate is extremely sensitive\nto small variations of the applied magnetic field, and can be tuned up to a\nstriking six orders of magnitude for quite realistic values of magnetic field.\nMoreover, we evidence the fundamental role played by the magnetoplasmon\npolaritons supported by the graphene monolayer as the dominant channel for the\nRET within a certain distance range. Our results suggest that magneto-optical\nmedia may take the manipulation of energy transfer between quantum emitters to\na whole new level, and broaden even more its great spectrum of applications.",
        "positive": "Conditions for the occurrence of Coulomb blockade in phosphorene quantum\n  dots at room temperature: We study the addition energy spectra of phosphorene quantum dots focusing on\nthe role of dot size, edges passivation, number of layers and dielectric\nconstant of the substrate where the dots are deposited. We show that for\nsufficiently low dielectric constants ($\\varepsilon_{sub} < 4$), Coulomb\nblockade can be observed in dot sizes larger than 10 nm, for both passivated\nand unpassivated edges. For higher dielectric constants (up to\n$\\varepsilon_{sub} = 30$), Coulomb blockade demands smaller dot sizes, but this\ndepends whether the edges are passivated or not. This dramatic role played by\nthe substrate is expected to impact on the development of application based on\nphosphorene quantum dots."
    },
    {
        "anchor": "Effect of mechanical stresses on the coercive force of the heterophase\n  non-interacting nanoparticles: The theoretical analysis of the effect of uniaxial stress on the\nmagnetization of the system of noninteracting nanoparticles is done by an\nexample of heterophase particles of maghemite, epitaxially coated with cobalt\nferrite. It is shown that stretching leads to a decrease in the coercive force\n$H_c$, and compression leads to its growth. The residual saturation\nmagnetization $I_{rs}$ of nanoparticles does not change. With increasing of\ninterfacial exchange interaction, coercive force varies nonmonotonically",
        "positive": "Superconducting transistors: A boost for quantum computing: A niobium titanite nitride-based superconducting nanodevice in which the\nJosephson critical current can be modulated by a gate voltage - a Cooper-pair\ntransistor - has proven a remarkably long parity lifetime exceeding one minute\nat temperatures close to absolute zero."
    },
    {
        "anchor": "From Hermitian critical to non-Hermitian point-gapped phases: Recent years have seen a growing interest in topological phases beyond the\nstandard paradigm of gapped, isolated systems. One recent direction is to\nexplore topological features in non-hermitian systems that are commonly used as\neffective descriptions of open systems. Another direction explores the fate of\ntopology at critical points, where the bulk gap collapses. One interesting\nobservation is that both systems, though very different, share certain\ntopological features. For instance, both systems can host half-integer\nquantized winding numbers and have very similar entanglement spectra. Here, we\nmake this similarity explicit by showing the equivalence of topological\ninvariants in critical systems with non-hermitian point-gap phases, in the\npresence of sublattice symmetry. This correspondence may carry over to other\nfeatures beyond topological invariants, and may even be helpful to deepen our\nunderstanding of non-hermitian systems using our knowledge of critical systems,\nand vice versa.",
        "positive": "Mutual synchronization of nano-oscillators driven by pure spin current: We report the experimental observation of mutual synchronization of magnetic\nnanooscillators driven by pure spin current generated by nonlocal spin\ninjection. We show that the oscillators efficiently synchronize due to the\ndirect spatial overlap of the dynamical modes excited by spin current, which is\nfacilitated by the large size of the auto-oscillation area inherent to these\ndevices. The synchronization occurs within an interval of the driving current\ndetermined by the competition between the dynamic nonlinearity that facilitates\nsynchronization, and the short-wavelength magnetic fluctuations enhanced by the\nspin current that suppress synchronization. The demonstrated synchronization\neffects can be utilized to control the spatial and spectral characteristics of\nthe dynamical states induced by spin currents."
    },
    {
        "anchor": "Tuning of the spin-orbit interaction in two-dimensional GaAs holes via\n  strain: We report direct measurements of the spin-orbit interaction induced\nspin-splitting in a modulation-doped GaAs two-dimensional hole system as a\nfunction of anisotropic, in-plane strain. The change in spin-subband densities\nreveals a remarkably strong dependence of the spin-splitting on strain, with up\nto about 20% enhancement of the splitting upon the application of only about 2\nx 10^{-4} strain. The results are in very good agreement with our numerical\ncalculations of the strain-induced spin-splitting.",
        "positive": "Electronic transport in double-nanowire superconducting islands with\n  multiple terminals: We characterize in-situ grown parallel nanowires bridged by a superconducting\nisland. The magnetic-field and temperature dependence of Coulomb blockade peaks\nmeasured across different pairs of nanowire ends are consistent with a sub-gap\nstate extended over the hybrid parallel-nanowire island. Being gate-tunable,\naccessible by multiple terminals and free of quasiparticle poisoning, these\nnanowires show promise for the implementation of several proposals that rely on\nparallel nanowire platforms."
    },
    {
        "anchor": "High On-Off Ratio Bilayer Graphene Complementary Field Effect\n  Transistors: In this paper, we propose a novel S/D engineering for dual-gated Bilayer\nGraphene (BLG) Field Effect Transistor (FET) using doped semiconductors (with a\nbandgap) as source and drain to obtain unipolar complementary transistors. To\nsimulate the device, a self-consistent Non-Equilibrium Green's Function (NEGF)\nsolver has been developed and validated against published experimental data.\nUsing the simulator, we predict an on-off ratio in excess of $10^4$ and a\nsubthreshold slope of ~110mV/decade with excellent scalability and current\nsaturation, for a 20nm gate length unipolar BLG FET. However, the performance\nof the proposed device is found to be strongly dependent on the S/D series\nresistance effect. The obtained results show significant improvements over\nexisting reports, marking an important step towards bilayer graphene logic\ndevices.",
        "positive": "The Geometric phase and fractional orbital angular momentum states in\n  electron vortex beams: We study here fractional orbital angular momentum (OAM) states in electron\nvortex beams (EVB) from the perspective of geometric phase. We have considered\nthe skyrmionic model of an electron, where it is depicted as a scalar electron\norbiting around the vortex line, which gives rise to the spin degrees of\nfreedom. The geometric phase acquired by the scalar electron orbiting around\nthe vortex line induces the spin-orbit interaction, which leads to the\nfractional OAM states with non-quantized monopole charge associated with the\ncorresponding geometric phase. This involves tilted vortex in EVBs. The\nmonopole charge undergoes the renormalization group (RG) flow, which\nincorporates a length scale dependence making the fractional OAM states\nunstable upon propagation. It is pointed out that when EVBs move in an external\nmagnetic field, the Gouy phase associated with the Laguerre-Gaussian modes\nmodifies the geometric phase factor and a proper choice of the radial index\nhelps to have a stable fractional OAM state."
    },
    {
        "anchor": "Vibrational states of a water molecule in a nano-cavity of beryl crystal\n  lattice: Low-energy excitations of a single water molecule are studied when confined\nwithin a nano-size cage formed by the ionic crystal lattice. Optical spectra\nare measured of manganese doped beryl single crystal Mn:Be3Al2Si6O18, that\ncontains water molecules individually isolated in 0.51 nm diameter voids within\nthe crystal lattice. Two types of orientation are distinguished: water-I\nmolecules have their dipole moments aligned perpendicular to the c axis, and\ndipole moments of water-II molecules are parallel to the c-axis. The optical\nconductivity and permittivity spectra are recorded in terahertz and infrared\nranges, at frequencies from several wavenumbers up to 7000cm-1, at temperatures\nfrom 5K to 300K and for two polarizations, when the electric vector E of the\nradiation is parallel and perpendicular to the c-axis. Comparative experiments\non as-grown and on dehydrated samples allow to identify the conductivity and\npermittivity spectra caused exclusively by water molecules. In the infrared\nrange well-known internal modes nu1, nu2 and nu3 of the H2O molecule are\nobserved for both polarizations, indicating the presence of water-I and\nwater-II molecules in the crystal. Spectra recorded below 1000cm-1 reveal a\nrich set of highly anisotropic features in the low-energy response of H2O\nmolecule in a crystalline nanocage. While for E parallel to c only two\nabsorption peaks are detected, at 90cm-1 and 160cm-1, several absorption bands\nare discovered for E perpendicular to c, each consisting of narrower\nresonances. The bands are assigned to librational and translational vibrations\nof water-I molecule that is weakly, via hydrogen bonds, coupled to the nanocage\nwalls. A model is presented that explains the fine structure of the bands by\nsplitting of the energy levels due to quantum tunneling between the minima in a\nsix-well potential relief felt by a molecule within the cage.",
        "positive": "Wet etch methods for InAs nanowire patterning and self-aligned\n  electrical contacts: Advanced synthesis of semiconductor nanowires (NWs) enables their application\nin diverse fields, notably in chemical and electrical sensing, photovoltaics,\nor quantum electronic devices. In particular, Indium Arsenide (InAs) NWs are an\nideal platform for quantum devices, e.g. they may host topological Majorana\nstates. While the synthesis has been continously perfected, only few techniques\nwere developed to tailor individual NWs after growth. Here we present three wet\nchemical etch methods for the post-growth morphological engineering of InAs NWs\non the sub-100 nm scale. The first two methods allow the formation of\nself-aligned electrical contacts to etched NWs, while the third method results\nin conical shaped NW profiles ideal for creating smooth electrical potential\ngradients and shallow barriers. Low temperature experiments show that NWs with\netched segments have stable transport characteristics and can serve as building\nblocks of quantum electronic devices. As an example we report the formation of\na single electrically stable quantum dot between two etched NW segments."
    },
    {
        "anchor": "Ultrafast Relaxation Dynamics of Photoexcited Dirac Fermion in The Three\n  Dimensional Dirac Semimetal Cadmium Arsenide: Three dimensional (3D) Dirac semimetals which can be seen as 3D analogues of\ngraphene have attracted enormous interests in research recently. In order to\napply these ultrahigh-mobility materials in future electronic/optoelectronic\ndevices, it is crucial to understand the relaxation dynamics of photoexcited\ncarriers and their coupling with lattice. In this work, we report ultrafast\ntransient reflection measurements of the photoexcited carrier dynamics in\ncadmium arsenide (Cd3As2), which is one of the most stable Dirac semimetals\nthat have been confirmed experimentally. By using low energy probe photon of\n0.3 eV, we probed the dynamics of the photoexcited carriers that are\nDirac-Fermi-like approaching the Dirac point. We systematically studied the\ntransient reflection on bulk and nanoplate samples that have different doping\nintensities by tuning the probe wavelength, pump power and lattice temperature,\nand find that the dynamical evolution of carrier distributions can be retrieved\nqualitatively by using a two-temperature model. This result is very similar to\nthat of graphene, but the carrier cooling through the optical phonon couplings\nis slower and lasts over larger electron temperature range because the optical\nphonon energies in Cd3As2 are much lower than those in graphene.",
        "positive": "Third harmonic generation of undoped graphene in Hartree-Fock\n  approximation: We theoretically investigate the effects of Coulomb interaction, at the level\nof unscreened Hartree-Fock approximation, on third harmonic generation of\nundoped graphene in an equation of motion framework. The unperturbed electronic\nstates are described by a widely used two-band tight binding model, and the\nCoulomb interaction is described by the Ohno potential. The ground state is\nrenormalized by taking into account the Hartree-Fock term, and the optical\nconductivities are obtained by numerically solving the equations of motion. The\nabsolute values of conductivity for third harmonic generation depend on the\nphoton frequency $\\Omega$ as $\\Omega^{-n}$ for $\\hbar\\Omega<1$, and then show a\npeak as $3\\hbar\\Omega$ approaches the renormalized energy of the $M$ point.\nTaking into account the Coulomb interaction, $n$ is found to be $5.5$, which is\nsignificantly greater than the value of $4$ found with the neglect of the\nCoulomb interaction. Therefore the Coulomb interaction enhances third harmonic\ngeneration at low photon energies -- for our parameters $\\hbar\\Omega<0.8$~eV --\nand then reduces it until the photon energy reaches about $2.1$~eV. The effect\nof the background dielectric constant is also considered."
    },
    {
        "anchor": "Electrochemical response of biased nanoelectrodes in solution: Novel approaches to DNA sequencing and detection require the measurement of\nelectrical currents between metal probes immersed in ionic solution. Here, we\nexperimentally demonstrate that these systems maintain large background\ncurrents with a transient response that decays very slowly in time and noise\nthat increases with ionic concentration. Using a non-equilibrium stochastic\nmodel, we obtain an analytical expression for the ionic current that shows\nthese results are due to a fast electrochemical reaction at the electrode\nsurface followed by the slow formation of a diffusion layer. During the latter,\nions translocate in the weak electric field generated after the initial rapid\nscreening of the strong fields near the electrode surfaces. Our theoretical\nresults are in very good agreement with experimental findings.",
        "positive": "Absence of hyperfine effects in $^{13}$C-graphene spin valve devices: The carbon isotope $^{13}$C, in contrast to $^{12}$C, possesses a nuclear\nmagnetic moment and can induce electron spin dephasing in graphene. This effect\nis usually neglected due to the low abundance of $^{13}$C in natural carbon\nallotropes ($\\sim$1 %). Chemical vapor deposition (CVD) allows for artificial\nsynthesis of graphene solely from a $^{13}$C precursor, potentially amplifying\nthe influence of the nuclear magnetic moments. In this work we study the effect\nof hyperfine interactions in pure $^{13}$C-graphene on its spin transport\nproperties. Using Hanle precession measurements we determine the spin\nrelaxation time and observe a weak increase of $\\tau_{s}$ with doping and a\nweak change of $\\tau_{s}$ with temperature, as in natural graphene. For\ncomparison we study spin transport in pure $^{12}$C-graphene, also synthesized\nby CVD, and observe similar spin relaxation properties. As the signatures of\nhyperfine effects can be better resolved in oblique spin-valve and Hanle\nconfigurations, we use finite-element modeling to emulate oblique signals in\nthe presence of a hyperfine magnetic field for typical graphene properties.\nUnlike in the case of GaAs, hyperfine interactions with $^{13}$C nuclei\ninfluence electron spin transport only very weakly, even for a fully polarized\nnuclear system. Also, in the measurements of the oblique spin-valve and Hanle\neffects no hyperfine features could be resolved. This work experimentally\nconfirms the weak character of hyperfine interactions and the negligible role\nof $^{13}$C atoms in the spin dephasing processes in graphene."
    },
    {
        "anchor": "Closed-form weak localization magnetoconductivity in quantum wells with\n  arbitrary Rashba and Dresselhaus spin-orbit interactions: We derive a closed-form expression for the weak localization (WL) corrections\nto the magnetoconductivity of a 2D electron system with arbitrary Rashba\n$\\alpha$ and Dresselhaus $\\beta$ (linear) and $\\beta_3$ (cubic) spin-orbit\ninteraction couplings, in a perpendicular magnetic field geometry. In a system\nof reference with an in-plane $\\hat{z}$ axis chosen as the high spin-symmetry\ndirection at $\\alpha = \\beta$, we formulate a new algorithm to calculate the\nthree independent contributions that lead to WL. The antilocalization is\ncounterbalanced by the term associated with the spin-relaxation along\n$\\hat{z}$, dependent only on $\\alpha - \\beta$. The other term is generated by\ntwo identical scattering modes characterized by spin-relaxation rates which are\nexplicit functions of the orientation of the scattered momentum. Excellent\nagreement is found with data from GaAs quantum wells, where in particular our\ntheory correctly captures the shift of the minima of the WL curves as a\nfunction of $\\alpha/\\beta$. This suggests that the anisotropy of the effective\nspin relaxation rates is fundamental to understanding the effect of the SO\ncoupling in transport.",
        "positive": "Higher-order topology in plasmonic kagome lattices: We study the topological properties of a kagome plasmonic metasurface,\nmodelled with a coupled dipole method which naturally includes retarded long\nrange interactions. We demonstrate the system supports an obstructed atomic\nlimit phase through the calculation of Wilson loops. Then we characterise the\nhierarchy of topological boundary modes hosted by the subwavelength array of\nplasmonic nanoparticles: both one-dimensional edge modes as well as\nzero-dimensional corner modes. We determine the properties of these modes which\nrobustly confine light at subwavelength scales, calculate the local density of\nphotonic states at edge and corner modes frequencies, and demonstrate the\nselective excitation of delocalised corner modes in a topological cavity,\nthrough non-zero orbital angular momentum beam excitation."
    },
    {
        "anchor": "Parallel Matrix Multiplication Using Voltage Controlled Magnetic\n  Anisotropy Domain Wall Logic: The domain wall-magnetic tunnel junction (DW-MTJ) is a versatile device that\ncan simultaneously store data and perform computations. These three-terminal\ndevices are promising for digital logic due to their nonvolatility, low-energy\noperation, and radiation hardness. Here, we augment the DW-MTJ logic gate with\nvoltage controlled magnetic anisotropy (VCMA) to improve the reliability of\nlogical concatenation in the presence of realistic process variations. VCMA\ncreates potential wells that allow for reliable and repeatable localization of\ndomain walls. The DW-MTJ logic gate supports different fanouts, allowing for\nmultiple inputs and outputs for a single device without affecting area. We\nsimulate a systolic array of DW-MTJ Multiply-Accumulate (MAC) units with 4-bit\nand 8-bit precision, which uses the nonvolatility of DW-MTJ logic gates to\nenable fine-grained pipelining and high parallelism. The DW-MTJ systolic array\nprovides comparable throughput and efficiency to state-of-the-art CMOS systolic\narrays while being radiation-hard. These results improve the feasibility of\nusing domain wall-based processors, especially for extreme-environment\napplications such as space.",
        "positive": "Universal topological marker: We elaborate that for topological insulators and topological superconductors\ndescribed by Dirac models in any dimension and symmetry class, the topological\norder can be mapped to lattice sites by a universal topological marker.\nDeriving from a recently discovered momentum-space universal topological\ninvariant, we introduce a topological operator that consists of alternating\nprojectors to filled and empty lattice eigenstates and the position operators,\nmultiplied by the Dirac matrices that are omitted in the Hamiltonian. The\ntopological operator projected to lattice sites yields the topological marker,\nwhose form is explicitly constructed for every topologically nontrivial\nsymmetry class from 1D to 3D. The off-diagonal elements of the topological\noperator yields a nonlocal topological marker, which decays with a correlation\nlength that diverges at topological phase transitions, and represents a Wannier\nstate correlation function. Various prototype examples, including\nSu-Schrieffer-Heeger model, Majorana chain, Chern insulators,\nBernevig-Hughes-Zhang model, 2D chiral and helical $p$-wave superconductors,\nlattice model of $^{3}$He B-phase, and 3D time-reversal symmetric topological\ninsulators, etc, are employed to demonstrate the ubiquity of our formalism."
    },
    {
        "anchor": "Quantum Synchronization in Presence of Shot Noise: Synchronization is a widespread phenomenon encountered in many natural and\nengineered systems with nonlinear classical dynamics. How synchronization\nconcepts and mechanisms transfer to the quantum realm and whether features are\nuniversal or platform specific are timely questions of fundamental interest.\nHere, we present a new approach to model incoherently driven dissipative\nquantum systems susceptible to synchronization within the framework of\nJosephson photonics devices, where a dc-biased Josephson junction creates\n(non-classical) light in a microwave cavity. The combined quantum compound\nconstitutes a self-sustained oscillator with a neutrally stable phase. Linking\ncurrent noise to the full counting statistics of photon emission allows us to\ncapture phase diffusion, but moreover permits phase locking to an ac-signal and\nmutual synchronization of two such devices. Thereby one can observe phase\nstabilization leading to a sharp emission spectrum as well as unique photon\nemission statistics revealing shot noise induced phase slips. Two-time\nperturbation theory is used to obtain a reduced description of the oscillators\nphase dynamics in form of a Fokker-Planck equation in generalization of\nclassical synchronization theories.",
        "positive": "MNPBEM - A Matlab toolbox for the simulation of plasmonic nanoparticles: MNPBEM is a Matlab toolbox for the simulation of metallic nanoparticles\n(MNP), using a boundary element method (BEM) approach. The main purpose of the\ntoolbox is to solve Maxwell's equations for a dielectric environment where\nbodies with homogeneous and isotropic dielectric functions are separated by\nabrupt interfaces. Although the approach is in principle suited for arbitrary\nbody sizes and photon energies, it is tested (and probably works best) for\nmetallic nanoparticles with sizes ranging from a few to a few hundreds of\nnanometers, and for frequencies in the optical and near-infrared regime. The\ntoolbox has been implemented with Matlab classes. These classes can be easily\ncombined, which has the advantage that one can adapt the simulation programs\nflexibly for various applications."
    },
    {
        "anchor": "Current-Induced Dynamics of Chiral Magnetic Structures: Creation,\n  Motion, and Applications: Magnetic textures can be manipulated by electric currents via the mechanisms\nof spin-transfer and spin-orbit-torques. We review how these torques can be\nexploited to create chiral magnetic textures in magnets with broken inversion\nsymmetries, including domain walls and skyrmions. These chiral textures can\nalso be moved by (electric) currents and obey very rich dynamics. For example,\nmagnetic domain walls feature the famous Walker breakdown, and magnetic whirls\nare subject to the skyrmion Hall effect, which is rooted in their real-space\ntopology. These properties led to a variety of potential novel applications\nwhich we briefly overview.",
        "positive": "Electric-Field-control of spin rotation in bilayer graphene: The manipulation of the electron spin degree of freedom is at the core of the\nspintronics paradigm, which offers the perspective of reduced power\nconsumption, enabled by the decoupling of information processing from net\ncharge transfer. Spintronics also offers the possibility of devising hybrid\ndevices able to perform logic, communication, and storage operations. Graphene,\nwith its potentially long spin-coherence length, is a promising material for\nspin-encoded information transport. However, the small spin-orbit interaction\nis also a limitation for the design of conventional devices based on the\ncanonical Datta-Das spin-FET. An alternative solution can be found in magnetic\ndoping of graphene, or, as discussed in the present work, in exploiting the\nproximity effect between graphene and Ferromagnetic Oxides (FOs). Graphene in\nproximity to FO experiences an exchange proximity interaction (EPI), that acts\nas an effective Zeeman field for electrons in graphene, inducing a spin\nprecession around the magnetization axis of the FO. Here we show that in an\nappropriately designed double-gate field-effect transistor, with a bilayer\ngraphene channel and FO used as a gate dielectric, spin-precession of carriers\ncan be turned ON and OFF with the application of a differential voltage to the\ngates. This feature is directly probed in the spin-resolved conductance of the\nbilayer."
    },
    {
        "anchor": "Nodal phases in non-Hermitian wallpaper crystals: Symmetry and non-Hermiticity play pivotal roles in photonic lattices. While\nsymmetries such as parity-time ($\\mathcal{PT}$) symmetry have attracted ample\nattention, more intricate crystalline symmetries have been neglected in\ncomparison.\n  Here, we investigate the impact of the 17 wallpaper space groups of\ntwo-dimensional crystals on non-Hermitian band structures. We show that the\nnon-trivial space group representations enforce degeneracies at high symmetry\npoints and dictate their dispersion away from these points. In combination with\neither $\\mathcal{T}$ or $\\mathcal{PT}$, the symmorphic p4mm symmetry, as well\nas the non-symmorphic p2mg, p2gg, and p4gm symmetries, protect novel\nexceptional chains intersecting at the pertinent high symmetry points.",
        "positive": "Probing Wigner correlations in a suspended carbon nanotube: The influence of the electron-vibron coupling on the transport properties of\na strongly interacting quantum dot built in a suspended carbon nanotube is\nanalyzed. The latter is probed by a charged AFM tip scanned along the axis of\nthe CNT which induces oscillations of the chemical potential and of the linear\nconductance. These oscillations are due to the competition between finite-size\neffects and the formation of a Wigner molecule for strong interactions. Such\noscillations are shown to be suppressed by the electron-vibron coupling. The\nsuppression is more pronounced in the regime of weak Coulomb interactions,\nwhich ensures that probing Wigner correlations in such a system is in principle\npossible."
    },
    {
        "anchor": "Interplay of ferroelectricity and single electron tunneling: We investigate the interplay of ferroelectricity and quantum electron\ntransport at the nanoscale in the regime of Coulomb blockade. Ferroelectric\npolarization in this case is no longer the external parameter but should be\nself-consistently calculated along with electron hopping probabilities leading\nto new physical transport phenomena studying in this paper. These phenomena\nappear mostly due to effective screening of a grain electric field by\nferroelectric environment rather than due to polarization dependent tunneling\nprobabilities. At small bias voltages polarization can be switched by a single\nexcess electron in the grain. In this case transport properties of SET exhibit\nthe instability (memory effect).",
        "positive": "Spin memory and spin-lattice relaxation in two-dimensional hexagonal\n  crystals: We propose a theory of spin relaxation of electrons and holes in\ntwo-dimensional hexagonal crystals such as atomic layers of transition metal\ndichalcogenides (MoS2, WSe2, etc). We show that even in intrinsically\ndefectless crystals, their flexural deformations are able to generate spin\nrelaxation of carriers. Based on symmetry analysis, we formulate a generic\nmodel for spin-lattice coupling between electrons and flexural deformations,\nand use it to determine temperature and material-dependent spin lifetimes in\natomic crystals in ambient conditions."
    },
    {
        "anchor": "Local Hall effect in hybrid ferromagnetic/semiconductor devices: We have investigated the magnetoresistance of ferromagnet-semiconductor\ndevices in an InAs two-dimensional electron gas system in which the magnetic\nfield has a sinusoidal profile. The magnetoresistance of our device is large.\nThe longitudinal resistance has an additional contribution which is odd in\napplied magnetic field. It becomes even negative at low temperature where the\ntransport is ballistic. Based on the numerical analysis, we confirmed that our\ndata can be explained in terms of the local Hall effect due to the profile of\nnegative and positive field regions. This device may be useful for future\nspintronic applications.",
        "positive": "Viscoelastic-electromagnetism and Hall viscosity: We introduce a kind of electromagnetism, which we call\nviscoelastic-electromagnetism, to investigate viscoelastic transport phenomena.\nIt is shown that Cartan's formalism of general relativity is essential for\nviscoelastic theory, and then the corresponding electric and magnetic fields\nare regarded as a velocity gradient and a Burgers vector density, respectively.\nAs an application of this formalism, the Streda formula for the Hall viscosity\nis obtained."
    },
    {
        "anchor": "Energy-level pinning and the 0.7 spin state in one dimension: GaAs\n  quantum wires studied using finite-bias spectroscopy: We study the effects of electron-electron interactions on the energy levels\nof GaAs quantum wires (QWs) using finite-bias spectroscopy. We probe the energy\nspectrum at zero magnetic field, and at crossings of opposite-spin-levels in\nhigh in-plane magnetic field B. Our results constitute direct evidence that\nspin-up (higher energy) levels pin to the chemical potential as they populate.\nWe also show that spin-up and spin-down levels abruptly rearrange at the\ncrossing in a manner resembling the magnetic phase transitions predicted to\noccur at crossings of Landau levels. This rearranging and pinning of subbands\nprovides a phenomenological explanation for the 0.7 structure, a\none-dimensional (1D) nanomagnetic state, and its high-B variants.",
        "positive": "Quasiparticle relaxation in superconducting nanostructures: We examine energy relaxation of non-equilibrium quasiparticles in \"dirty\"\nsuperconductors with the electron mean free path much shorter than the\nsuperconducting coherence length. Relaxation of low-energy non-equilibrium\nquasiparticles is dominated by phonon emission. We derive the corresponding\ncollision integral and find the quasiparticle relaxation rate. The latter is\nsensitive to the breaking of time reversal symmetry (TRS) by a magnetic field\n(or magnetic impurities). As a concrete application of the developed theory, we\naddress quasiparticle trapping by a vortex and a current-biased constriction.\nWe show that trapping of hot quasiparticles may predominantly occur at\ndistances from the vortex core, or the constriction, significantly exceeding\nthe superconducting coherence length."
    },
    {
        "anchor": "Lattice models with exactly solvable topological hinge and corner states: We devise a generic recipe for constructing $D$-dimensional lattice models\nwhose $d$-dimensional boundary states, located on surfaces, hinges, corners,\nand so forth, can be obtained exactly. The solvability is rooted in the\nunderlying lattice structure and as such does not depend on fine tuning,\nallowing us to track their evolution throughout various phases and across phase\ntransitions. Most saliently, our models provide \"boundary solvable\" examples of\nthe recently introduced higher-order topological phases. We apply our general\napproach to breathing and anisotropic kagome and pyrochlore lattices for which\nwe obtain exact corner eigenstates, and to periodically driven two-dimensional\nmodels as well as to three-dimensional lattices where we present exact\nsolutions corresponding to one-dimensional chiral states at the hinges of the\nlattice. We relate the higher-order topological nature of these models to\nreflection symmetries in combination with their provenance from\nlower-dimensional conventional topological phases.",
        "positive": "Performance of a bipolar single electron device: A small scale bipolar transistor with polysilicon emitter will, depending on\nthe emitter window size, display suppression of the hole tramsport due to\nsingle electron effects. In this paper the resulting base current suppression\nis computed in terms of the orthodox theory of single electron tunneling and a\nrecombination time approximation. The possible application of the transistor as\nreadout system for Coulomb blockade device circuits is discussed."
    },
    {
        "anchor": "Perfect transmission and Aharanov-Bohm oscillations in topological\n  insulator nanowires with nonuniform cross section: Topological insulator nanowires with uniform cross section, combined with a\nmagnetic flux, can host both a perfectly transmitted mode and Majorana zero\nmodes. Here we consider nanowires with rippled surfaces---specifically, wires\nwith a circular cross section with a radius varying along its axis---and\ncalculate their transport properties. At zero doping, chiral symmetry places\nthe clean wires (no impurities) in the AIII symmetry class, which results in a\n$\\mathbb{Z}$ topological classification. A magnetic flux threading the wire\ntunes between the topologically distinct insulating phases, with perfect\ntransmission obtained at the phase transition. We derive an analytical\nexpression for the exact flux value at the transition. Both doping and disorder\nbreaks the chiral symmetry and the perfect transmission. At finite doping, the\ninterplay of surface ripples and disorder with the magnetic flux modifies\nquantum interference such that the amplitude of Aharonov-Bohm oscillations\nreduces with increasing flux, in contrast to wires with uniform surfaces where\nit is flux-independent.",
        "positive": "Stacking boundaries and transport in bilayer graphene: Pristine bilayer graphene behaves in some instances as an insulator with a\ntransport gap of a few meV. This behaviour has been interpreted as the result\nof an intrinsic electronic instability induced by many-body correlations.\nIntriguingly, however, some samples of similar mobility exhibit good metallic\nproperties, with a minimal conductivity of the order of $2e^2/h$. Here we\npropose an explanation for this dichotomy, which is unrelated to electron\ninteractions and based instead on the reversible formation of boundaries\nbetween stacking domains (`solitons'). We argue, using a numerical analysis,\nthat the hallmark features of the previously inferred many-body insulating\nstate can be explained by scattering on boundaries between domains with\ndifferent stacking order (AB and BA). We furthermore present experimental\nevidence, reinforcing our interpretation, of reversible switching between a\nmetallic and an insulating regime in suspended bilayers when subjected to\nthermal cycling or high current annealing."
    },
    {
        "anchor": "Enhancing the Coherence of a Spin Qubit by Operating it as a Feedback\n  Loop That Controls its Nuclear Spin Bath: In many realizations of electron spin qubits the dominant source of\ndecoherence is the fluctuating nuclear spin bath of the host material. The\nslowness of this bath lends itself to a promising mitigation strategy where the\nnuclear spin bath is prepared in a narrowed state with suppressed fluctuations.\nHere, this approach is realized for a two-electron spin qubit in a GaAs double\nquantum dot and a nearly ten-fold increase in the inhomogeneous dephasing time\n$T_2^*$ is demonstrated. Between subsequent measurements, the bath is prepared\nby using the qubit as a feedback loop that first measures its nuclear\nenvironment by coherent precession, and then polarizes it depending on the\nfinal state. This procedure results in a stable fixed point at a nonzero\npolarization gradient between the two dots, which enables fast universal qubit\ncontrol.",
        "positive": "Fractional Fermions with Non-Abelian Statistics: We introduce a novel class of low-dimensional topological tight-binding\nmodels that allow for bound states that are fractionally charged fermions and\nexhibit non-Abelian braiding statistics. The proposed model consists of a\ndouble (single) ladder of spinless (spinful) fermions in the presence of\nmagnetic fields. We study the system analytically in the continuum limit as\nwell as numerically in the tight-binding representation. We find a topological\nphase transition with a topological gap that closes and reopens as a function\nof system parameters and chemical potential. The topological phase is of the\ntype BDI and carries two degenerate mid-gap bound states that are localized at\nopposite ends of the ladders. We show numerically that these bound states are\nrobust against a wide class of perturbations."
    },
    {
        "anchor": "Non-equilibrium transport in the pseudospin-1 Dirac-Weyl system: Solid state materials hosting pseudospin-1 quasiparticles have attracted a\ngreat deal of recent attention. In these materials, the energy band contains of\na pair of Dirac cones and a flat band through the connecting point of the\ncones. As the \"caging\" of carriers with a zero group velocity, the flat band\nitself has zero conductivity. However, in a non-equilibrium situation where a\nconstant electric field is suddenly switched on, the flat band can enhance the\nresulting current in both the linear and nonlinear response regimes through\ndistinct physical mechanisms. Using the ($2+1$) dimensional pseudospin-$1$\nDirac-Weyl system as a concrete setting, we demonstrate that, in the weak field\nregime, the interband current is about twice larger than that for\npseudospin-1/2 system due to the interplay between the flat band and the\nnegative band, with the scaling behavior determined by the Kubo formula. In the\nstrong field regime, the intraband current is $\\sqrt{2}$ times larger than that\nin the pseudospin-1/2 system, due to the additional contribution from particles\nresiding in the flat band. In this case, the current and field follows the\nscaling law associated with Landau-Zener tunneling. These results provide a\nbetter understanding of the role of the flat band in non-equilibrium transport\nand are experimentally testable using electronic or photonic systems.",
        "positive": "Interplay between electronic topology and crystal symmetry:\n  Dislocation-line modes in topological band-insulators: We elucidate the general rule governing the response of dislocation lines in\nthree-dimensional topological band insulators. According to this ${\\bf\nK}\\text{-}{\\bf b}\\text{-}{\\bf t}$ rule, the lattice topology, represented by\ndislocation lines oriented in direction ${\\bf t}$ with Burgers vector ${\\bf\nb}$, combines with the electronic-band topology, characterized by the\nband-inversion momentum ${\\bf K}_{\\rm inv}$, to produce gapless propagating\nmodes when the plane orthogonal to the dislocation line features a band\ninversion with a nontrivial ensuing flux $\\Phi={\\bf K}_{\\rm inv}\\cdot {\\bf\nb}\\,\\, ({\\rm mod\\,\\,2\\pi})$. Although it has already been discovered by Y. Ran\n{\\it et al.}, Nature Phys. {\\bf 5}, 298 (2009), that dislocation lines host\npropagating modes, the exact mechanism of their appearance in conjunction with\nthe crystal symmetries of a topological state is provided by the ${\\bf\nK}\\text{-}{\\bf b}\\text{-}{\\bf t}$ rule . Finally, we discuss possible\nexperimentally consequential examples in which the modes are oblivious for the\ndirection of propagation, such as the recently proposed\ntopologically-insulating state in electron-doped BaBiO$_3$."
    },
    {
        "anchor": "Periodic Modulation Effect on Self-Trapping of Two weakly coupled\n  Bose-Einstein Condensates: With phase space analysis approach, we investigate thoroughly the\nself-trapping phenomenon for two weakly coupled Bose-Einstein condensates (BEC)\nin a symmetric double-well potential. We identify two kinds of self-trapping by\ntheir different relative phase behavior. With applying a periodic modulation on\nthe energy bias of the system we find the occurrence of the self-trapping can\nbe controlled, saying, the transition parameters can be adjusted effectively by\nthe periodic modulation. Analytic expressions for the dependence of the\ntransition parameters on the modulation parameters are derived for high and low\nfrequency modulations. For an intermediate frequency modulation, we find the\nresonance between the periodic modulation and nonlinear Rabi oscillation\ndramatically affects the tunnelling dynamics and demonstrate many novel\nphenomena. Finally, we study the effects of many-body quantum fluctuation on\nself-trapping and discuss the possible experimental realization of the model.",
        "positive": "Chiral edge soliton in nonlinear Chern systems: We study the effect on the chiral edge states by including a nonlinearity to\na Chern insulator which has two chiral edge states with opposite chiralities.\nWe explore a quench dynamics by giving a pulse to one site on an edge and\nanalyzing the time evolution of a wave packet. Without the nonlinearity, an\ninitial pulse spreads symmetrically and diffuses. On the other hand, with the\nnonlinearity present, a solitary wave is formed by the self-trapping effect of\nthe nonlinear term and undergoes a unidirectional propagation along the edge,\nwhich we identify as a chiral edge soliton. A further increase of the\nnonlinearity induces a self-trapping transition, where the chiral wave packet\nstops its motion. It is intriguing that the nonlinearity is controlled only by\nchanging the initial condition without changing a sample."
    },
    {
        "anchor": "Predictive computational modeling of optical absorption and dark\n  currents of the 6.1\u00c5 Type-II superlattice absorbers for MWIR and LWIR\n  applications: A holistic computational analysis is developed to advance models for quantum\nefficiency of InAs/GaSb superlattice-based photodetectors. Starting with the\nelectronic band characteristics computed by taking the InSb at the interface\nusing the 8-band k.p approach, we demonstrate the impact of InAs and GaSb\nwidths on the the bandgap, carrier concentration, and the oscillator strength\nfor type-II superlattices. Subsequently, the alteration of these\ncharacteristics due to the extra AlSb layer in the M superlattice is\ninvestigated. Extending our models for determining TE- and TM-polarized optical\nabsorption, our calculations reveal that the TE-polarized absorption shows a\nsubstantial influence near the conduction-heavy hole band transition energy,\nwhich eventually diminishes, owing to the dominant TM-contribution due to the\nconduction-light hole band transition. Extending our analysis to the dark\ncurrents, we notice that Schokley-Read-Hall recombination dominates at lower\ndoping levels, while radiative recombination becomes dominant at higher doping\nlevels. Auger transitions are also predicted using the conduction\nmini-bandwidth and the transition probabilities. We show that long-wavelength M\nsuperlattice structures exhibit longer diffusion lengths due to higher\nrecombination lifetimes, indicating that it can be heavily doped to improve the\nquantum efficiency. Mid-wavelength M superlattices show comparable\ncharacteristics, resulting in a 7% increase in quantum efficiency. Further, we\nanalyze the density of states blocked by the barrier; crucial for XBp\nphotodetector after absorber examination. Our work thus sets a stage for a\nholistic and predictive theory aided analysis of the type-II superlattice\nabsorbers, from the atomistic interfacial details all the way to the dark\ncurrents and photoluminescence spectra.",
        "positive": "Spin Hall noise: We measure the low-frequency thermal fluctuations of pure spin current in a\nPlatinum film deposited on yttrium iron garnet via the inverse spin Hall effect\n(ISHE)-mediated voltage noise as a function of the angle $\\alpha$ between the\nmagnetization and the transport direction. The results are consistent with the\nfluctuation dissipation theorem in terms of the recently discovered spin Hall\nmagnetoresistance (SMR). We present a microscopic description of the $\\alpha$\ndependence of the voltage noise in terms of spin current fluctuations and ISHE."
    },
    {
        "anchor": "New model for system of mesoscopic Josephson contacts: Quantum fluctuations of the phases of the order parameter in 2D arrays of\nmesoscopic Josephson junctions and their effect on the destruction of\nsuperconductivity in the system are investigated by means of a quantum-cosine\nmodel that is free of the incorrect application of the phase operator. The\nproposed model employs trigonometric phase operators and makes it possible to\nstudy arrays of small superconducting granules, pores filled with superfluid\nhelium, or Josephson junctions in which the average number of particles $n_0$\n(effective bosons, He atoms, and so on) is small, and the standard approach\nemploying the phase operator and the particle number operator as conjugate ones\nis inapplicable. There is a large difference in the phase diagrams between\narrays of macroscopic and mesoscopic objects for $n_0 < 5$ and $U<J$ ($U$ is\nthe characteristic interaction energy of the particle per granule and $J$ is\nthe Josephson coupling constant). Reentrant superconductivity phenomena are\ndiscussed.",
        "positive": "Longitudinal-transverse splitting and fine structure of Fermi polarons\n  in two-dimensional semiconductors: Interaction of excitons with resident charge carriers in semiconductors gives\nrise to bound three-particle complexes, trions, whose optical response is\nconveniently described in the framework of many-body correlated Fermi polaron\nstates. These states are formed as a result of correlation of photocreated\ntrion with the Fermi sea hole and possess the angular momentum component of\n$\\pm 1$ depending on the helicity of the photon. We study theoretically the\nenergy spectrum fine structure of Fermi polarons in two-dimensional\nsemiconductors based on transition metal dichalcogenides. We demonstrate both\nby the symmetry analysis and microscopic calculation that the Fermi polarons\nwith nonzero in-plane wavevector $\\bf k$ are split, similarly to the neutral\nexciton states, into the linearly polarized longitudinal and transverse, with\nrespect to the $\\bf k$, states. The origin of this longitudinal-transverse\nsplitting is the long-range electron-hole exchange interaction that can be also\ndescribed as the interaction of Fermi polarons with their induced\nelectromagnetic field. The effective Hamiltonian describing the Fermi polaron\nfine structure is derived, and its parameters are determined from the\nmicroscopic model."
    },
    {
        "anchor": "Disorder, synchronization and phase locking in non-equilibrium\n  Bose-Einstein condensates: We review some theories of non-equilibrium Bose-Einstein condensates in\npotentials, in particular of the Bose-Einstein condensate of polaritons. We\ndiscuss such condensates, which are steady-states established through a balance\nof gain and loss, in the complementary limits of a double-well potential and a\nrandom disorder potential. For equilibrium condensates, the former corresponds\nto a Josephson junction, whereas the latter is the setting for the\nsuperfluid/Bose glass transition. We explore the non-equilibrium generalization\nof these phenomena, and highlight connections with mode selection and\nsynchronization.",
        "positive": "Spin and valley waves in Dirac semimetals with population imbalance: We find an intervalley wave collective mode in two- and three-dimensional\nDirac semimetals in the presence of a valley population imbalance. The\ndispersion relation of this mode is gapless, proportional to the square of the\nwave vector at small frequencies, and inversely proportional to the\nelectron-electron exchange interaction energy. The valley wave serves as an\nenergy gain source for the external field, that generates the intervalley\ntransitions. The spin wave analog is discussed for the case of a semimetal with\nnonequilibrium spin orientation."
    },
    {
        "anchor": "Imaging orbital ferromagnetism in a moir\u00e9 Chern insulator: Electrons in moir\\'e flat band systems can spontaneously break time reversal\nsymmetry, giving rise to a quantized anomalous Hall effect. Here we use a\nsuperconducting quantum interference device to image stray magnetic fields in\none such system composed of twisted bilayer graphene aligned to hexagonal boron\nnitride. We find a magnetization of several Bohr magnetons per charge carrier,\ndemonstrating that the magnetism is primarily orbital in nature. Our\nmeasurements reveal a large change in the magnetization as the chemical\npotential is swept across the quantum anomalous Hall gap consistent with the\nexpected contribution of chiral edge states to the magnetization of an orbital\nChern insulator. Mapping the spatial evolution of field-driven magnetic\nreversal, we find a series of reproducible micron scale domains whose\nboundaries host chiral edge states.",
        "positive": "Hysteretic magnetoresistance in nanowire devices due to stray fields\n  induced by micromagnets: We study hysteretic magnetoresistance in InSb nanowires due to stray magnetic\nfields from CoFe micromagnets. Devices without any ferromagnetic components\nshow that the magnetoresistance of InSb nanowires commonly exhibits either a\nlocal maximum or local minimum at zero magnetic field. Switching of microstrip\nmagnetizations then results in positive or negative hysteretic dependence as\nconductance maxima or minima shift with respect to the global external field.\nStray fields are found to be in the range of tens of millitesla, comparable to\nthe scale over which the nanowire magnetoresistance develops. We observe that\nthe stray field signal is similar to that obtained in devices with\nferromagnetic contacts (spin valves). We perform micromagnetic simulations\nwhich are in reasonable agreement with the experiment. The use of locally\nvarying magnetic fields may bring new ideas for Majorana circuits in which\nnanowire networks require control over field orientation at the nanoscale."
    },
    {
        "anchor": "Simulation of the Elastic Properties of Reinforced Kevlar-Graphene\n  Composites: The compressive strength of unidirectional fiber composites in the form of\nKevlar yarn with a thin outer layer of graphene was investigated and modeled.\nSuch fiber structure may be fabricated by using a strong chemical bond between\nKevlar yarn and graphene sheets. Chemical functionalization of graphene and\nKevlar may achieved by modification of appropriate surface-bound functional\n(e.g., carboxylic acid) groups on their surfaces. In this report we studied\nelastic response to unidirectional in-plane applied load with load peaks along\nthe diameter. The 2D linear elasticity model predicts that significant\nstrengthening occurs when graphene outer layer radius is about 4 % of kevlar\nyarn radius. The polymer chains of Kevlar are linked into locally planar\nstructure by hydrogen bonds across the chains, with transversal strength\nconsiderably weaker than longitudinal one. This suggests that introducing outer\nenveloping layer of graphene, linked to polymer chains by strong chemical bonds\nmay significantly strengthen Kevlar fiber with respect to transversal\ndeformations.",
        "positive": "Synthetic dimensions in integrated photonics: From optical isolation to\n  4D quantum Hall physics: Recent technological advances in integrated photonics have spurred on the\nstudy of topological phenomena in engineered bosonic systems. Indeed, the\ncontrollability of silicon ring-resonator arrays has opened up new perspectives\nfor building lattices for photons with topologically nontrivial bands and\nintegrating them into photonic devices for practical applications. Here, we\npush these developments even further by exploiting the different modes of a\nsilicon ring resonator as an extra dimension for photons. Tunneling along this\nsynthetic dimension is implemented via an external time-dependent modulation\nthat allows for the generation of engineered gauge fields. We show how this\napproach can be used to generate a variety of exciting topological phenomena in\nintegrated photonics, ranging from a topologically-robust optical isolator in a\nspatially one-dimensional (1D) ring-resonator chain to a driven-dissipative\nanalog of the 4D quantum Hall effect in a spatially 3D resonator lattice. Our\nproposal paves the way towards the use of topological effects in the design of\nnovel photonic lattices supporting many frequency channels and displaying\nhigher connectivities."
    },
    {
        "anchor": "Density of states in a two-dimensional chiral metal with vacancies: We study quantum interference effects in a two-dimensional chiral metal\n(bipartite lattice) with vacancies. We demonstrate that randomly distributed\nvacancies constitute a peculiar type of chiral disorder leading to strong\nmodifications of critical properties at zero energy as compared to conventional\nchiral metals. In particular, the average density of states diverges as $\\rho\n\\propto E^{-1} |\\ln E|^{-3/2}$ and the correlation length $L_c \\propto\n\\sqrt{|\\ln E|}$ in the limit $E \\to 0$. When the average density of vacancies\nis different in the two sublattices, a finite concentration of zero modes\nemerges and a gap in the quasiclassical density of states opens around zero\nenergy. Interference effects smear this gap resulting in exponentially small\ntails at low energies.",
        "positive": "Noise signatures for determining chiral Majorana fermion modes: The conductance measurement of a half quantized plateau in a quantum\nanomalous Hall insulator-superconductor structure is reported by a recent\nexperiment [Q. L. He \\textit{et al.}, Science 357, 294-299 (2017)], which\nsuggests the existence of the chiral Majorana fermion modes. However, such half\nquantized conductance plateau may also originates from a disorder-induced\nmetallic phase. To identify the exact mechanism, we study the transport\nproperties of such a system in the presence of strong disorders. Our results\nshow that the local current density distributions of these two mechanisms are\ndifferent. In particular, the current noises measurement can be used to\ndistinguish them without any further fabrication of current experimental setup."
    },
    {
        "anchor": "Protocols for characterizing quantum transport through nano-structures: In this work, we have analyzed the exact closed-form solutions for transport\nquantities through a mesoscopic region which may be characterized by a\npolynomial functional of resonant transmission functions. These are then\nutilized to develop considerably improved protocols for parameters relevant for\nquantum transport through molecular junctions and quantum dots. The protocols\nare shown to be experimentally feasible and should yield the parameters at much\nhigher resolution than the previously proposed ones.",
        "positive": "Enhancing All-Optical Switching of Magnetization by He Ion Irradiation: All-optical switching (AOS) of magnetization by a single femtosecond laser\npulse in Co/Gd based synthetic ferrimagnets is the fastest magnetization\nswitching process. On the other hand, He ion irradiation has become a promising\ntool for interface engineering of spintronic material platforms, giving rise to\nsignificant modification of magnetic properties. In this paper, we explore the\nuse of He ion irradiation to enhance single pulse AOS of Co/Gd bilayer-based\nsynthetic ferrimagnets. The intermixing of the constituent magnetic layers by\nHe ion irradiation was both numerically simulated and experimentally verified.\nWe theoretically modelled the effects of intermixing on AOS using the layered\nmicroscopic 3-temperature model and found that AOS is enhanced significantly by\nbreaking the pristine Co/Gd interface through intermixing. Following this\nnotion, we studied the threshold fluence of AOS as a function of He ion\nirradiation fluence. We found that the AOS threshold fluence can be reduced by\nalmost 30%. Our study reveals the control of AOS by He ion irradiation, which\nopens up an industrially compatible approach for local AOS engineering."
    },
    {
        "anchor": "Enhanced Performance of Short-Channel Carbon Nanotube Field-Effect\n  Transistors Due to Gate-Modulated Electrical Contacts: We use numerical simulations to analyze recent experimental measurements of\nshort-channel carbon nanotube field-effect transistors with palladium contacts.\nWe show that the gate strongly modulates the contact properties, an effect that\nis distinct from that observed in Schottky barrier carbon nanotube transistors.\nThis modulation of the contacts by the gate allows for the realization of\nsuperior subthreshold swings for short channels, and improved scaling behavior.\nThese results further elucidate the behavior of carbon nanotube-metal contacts,\nand should be useful in the optimization of high-performance carbon nanotube\nelectronics.",
        "positive": "High volumetric capacitance near insulator-metal percolation transition: A new type of a capacitor with a very high volumetric capacitance is\nproposed. It is based upon the known phenomenon of a sharp increase of the\ndielectric constant of the metal-insulator composite in the vicinity of the\npercolation threshold, but still on the insulator side. The optimization\nsuggests that the metallic particles should be of nanoscale and that the\ndistance between planar electrodes should be somewhat larger than the\ncorrelation length of the percolation theory and 10 to 20 times larger than the\nsize of the particles while the area of the electrodes might be unlimited. The\nrandom electric field in the capacitors is found to be larger than the average\nfield corresponding to the potential difference of electrodes. This random\nfield is potentially responsible for dielectric breakdown. The estimated\nbreakdown voltage of the new capacitor shows that the stored energy density\nmight be significantly larger than that of electrolytic capacitors while the\nvolumetric capacitances might be comparable. The charging and discharging times\nshould be significantly smaller than corresponding times of batteries and even\nelectrolytic capacitors."
    },
    {
        "anchor": "Hydrodynamics on the lowest Landau level: Using the recently developed approach to quantum Hall physics based on\nNewton-Cartan geometry, we consider the hydrodynamics of an interacting system\non the lowest Landau level. We rephrase the non-relativistic fluid equations of\nmotion in a manner that manifests the spacetime diffeomorphism invariance of\nthe underlying theory. In the massless (or lowest Landau level) limit, the\nfluid obeys a force-free constraint which fixes the charge current. An entropy\ncurrent analysis further constrains the energy response, determining four\ntransverse response functions in terms of only two: an energy magnetization and\na thermal Hall conductivity. Kubo formulas are presented for all transport\ncoefficients and constraints from Weyl invariance derived. We also present a\nnumber of Streda-type formulas for the equilibrium response to external\nelectric, magnetic and gravitational fields.",
        "positive": "Multi-phonon Raman scattering in semiconductor nanocrystals: importance\n  of non-adiabatic transitions: Multi-phonon Raman scattering in semiconductor nanocrystals is treated taking\ninto account both adiabatic and non-adiabatic phonon-assisted optical\ntransitions. Because phonons of various symmetries are involved in scattering\nprocesses, there is a considerable enhancement of intensities of multi-phonon\npeaks in nanocrystal Raman spectra. Cases of strong and weak band mixing are\nconsidered in detail. In the first case, fundamental scattering takes place via\ninternal electron-hole states and is participated by s- and d-phonons, while in\nthe second case, when the intensity of the one-phonon Raman peak is strongly\ninfluenced by the interaction of an electron and of a hole with interface\nimperfections (e. g., with trapped charge), p-phonons are most active.\nCalculations of Raman scattering spectra for CdSe and PbS nanocrystals give a\ngood quantitative agreement with recent experimental results."
    },
    {
        "anchor": "Magnonic Hong-Ou-Mandel Effect: We carried out numerical simulations of propagation of spin waves (magnons in\nquantum language) in a yttrium-iron garnet film. The numerical model is based\non an original formalism. We demonstrated that a potential barrier for magnons,\ncreated by an Oersted field of a dc current flowing through a wire sitting on\ntop of the film, is able to act as an electrically controlled partly\ntransparent mirror for the magnons. We found that the mirror transparency can\nbe set to 50% by properly adjusting the current strength, thus creating a\nsemi-transparent mirror. A strong Hong-Ou-Mandel Effect for single magnons is\nexpected in this configuration. The effect must be seen as two single magnons,\nlaunched simultaneously into the film from two transducers located from the\nopposite sides of the mirror, creating a two-microwave-photon state at the\noutput port of one of the transducers. The probability of seeing those\ntwo-photon states at the output port of either transducer must be the same for\nboth transducers.",
        "positive": "Collective coordinate study of spin wave emission from dynamic domain\n  wall: We study theoretically the spin wave emission from a moving domain wall in a\nferromagnet. Introducing a deformation mode describing a modulation of the wall\nthickness in the collective coordinate description, we show that thickness\nvariation couples to the spin wave linearly and induces spin wave emission. The\ndominant emitted spin wave turns out to be polarized in the out-of wall plane\n($\\phi$)-direction. The emission contributes to the Gilbert damping parameter\nproportional to $\\hbar\\omega_\\phi/K$, the ratio of the angular frequency\n$\\omega_\\phi$ of $\\phi$ and the easy-axis anisotropy energy $K$."
    },
    {
        "anchor": "Evidence of nanoscale Anderson localization induced by intrinsic\n  compositional disorder in InGaN/GaN quantum wells by scanning tunneling\n  luminescence spectroscopy: We present direct experimental evidences of Anderson localization induced by\nthe intrinsic alloy compositional disorder of InGaN/GaN quantum wells. Our\napproach relies on the measurement of the luminescence spectrum under local\ninjection of electrons from a scanning tunneling microscope tip into a\nnear-surface single quantum well. Fluctuations in the emission line shape are\nobserved on a few-nanometer scale. Narrow emission peaks characteristic of\nsingle localized states are resolved. Calculations in the framework of the\nlocalization landscape theory provide the effective confining potential map\nstemming from composition fluctuations. This theory explains well the observed\nnanometer scale carrier localization and the energies of these Anderson-type\nlocalized states. The energy spreading of the emission from localized states is\nconsistent with the usually observed very broad photo- or electro-luminescence\nspectra of InGaN/GaN quantum well structures.",
        "positive": "Measurements of the Composite Fermion masses from the spin polarization\n  of 2-D electrons in the region $1<\u03bd<2$: Measurements of the reflectivity of a 2-D electron gas are used to deduce the\npolarization of the Composite Fermion hole system formed for Landau level\noccupancies in the regime 1<\\nu<2. The measurements are consistent with the\nformation of a mixed spin CF system and allow the density of states or\n`polarization' effective mass of the CF holes to be determined. The mass values\nat \\nu=3/2 are found to be ~1.9m_{e} for electron densities of 4.4 x 10^{11}\ncm^{-2}, which is significantly larger than those found from measurements of\nthe energy gaps at finite values of effective magnetic field."
    },
    {
        "anchor": "Tuning the electronic structure and magnetic coupling in armchair B$_2$S\n  nanoribbons using strain and staggered sublattice potential: Monolayer B$_2$S has been recently unveiled as a desirable honeycomb\nmonolayer with an anisotropic Dirac cone. We investigate the\nRuderman-Kittel-Kasuya-Yoshida (RKKY) interaction, between two magnetic\nimpurity moments in armchair-terminated B$_2$S nanoribbons in the presence of\nstrain and staggered sublattice potential. By using an accurate tight-binding\nmodel, we firstly study the electronic properties of all infinite-length\narmchair B$_2$S nanoribbons (ABSNRs), with different edges, in the presence of\nboth strain and staggered potential. The ABSNRs show different electronic and\nmagnetic behaviors due to different edge morphologies. The band gap energy of\nABSNRs depends strongly upon the applied staggered potential and thus one can\nengineer the electronic properties of the ABSNRs via tuning the external\nstaggered potential. A complete and fully reversible semiconductor (or\ninsulator) to metal transition has been observed via tuning the external\nstaggered potential, which can be easily realized experimentally. A prominent\nfeature is the presence of a quasiflat edge mode, isolated from the bulk modes\nin the ABSNRs belong to the family $M=6p$, with $M$ the width of the ABSNR and\n$p$ an integer number. The position of the quasi-flatbands(QFBs) in the energy\ndiagram of ABSNRs can be shifted by applying the in-plane strains. At a\ncritical staggered potential, for nanoribbons of arbitrary width, the QFB\nchanges to a perfect flatband. The RKKY interaction has an oscillating\nbehaviour in terms of the applied staggered potentials and width of the ribbon,\nsuch that for two magnetic adatoms randomly distributed on the surface of an\nABSNR the staggered potential can reverse the RKKY from antiferromagnetism to\nferromagnetism and vice versa. Our findings pave the way for applications in\nspintronics and pseudospin electronics devices based on ABSNRs.",
        "positive": "Gating classical information flow through spin chains by quantum phase\n  transitions: To push commercial electronics beyond its current size limits, atomic-scale\ncommunication channels and logic units need to be designed, making the use of\nquantum entities an imperative. In this regime, quantum fluctuations naturally\nbecome prominent, and are generally considered to be detrimental. Here we show\nthat for spin-based information processing, these fluctuations can be uniquely\nexploited to gate the flow of classical binary information across a magnetic\nchain. Moreover, this information flow can be controlled with a modest external\nmagnetic field that drives the system through different many-body quantum\nphases in which the orientation of the final spin does or does not reflect the\norientation of the initial input. Our results are general for a wide class of\nanisotropic spin chains that act as magnetic cellular automata, and suggest\nthat quantum fluctuations may play a unique role in driving classical\ninformation flow at the atomic scale."
    },
    {
        "anchor": "Evaluation of the Feasibility of Phosphorene for Electronic DNA\n  Sequencing Using Density Functional Theory Calculations: Electronic DNA sequencing using two-dimensional (2D) materials such as\ngraphene has recently emerged as the next-generation of DNA sequencing\ntechnology. Owing to its commercial availability and remarkable physical and\nconductive properties, graphene has been widely investigated for DNA sequencing\nby several theoretical and experimental groups. Despite this progress,\nsequencing using graphene remains a major challenge. This is due to the\nhydrophobic nature of graphene, which causes DNA bases to stick to its surface\nvia strong {\\pi}-{\\pi} interactions, reducing translocation speed and\nincreasing error rates. To circumvent this challenge, the scientific community\nhas turned its attention to other 2D materials beyond graphene. One such\nmaterial is phosphorene. In this article, we performed first-principle\ncomputational studies using density functional theory (DFT) to evaluate the\nability of phosphorene to distinguish individual DNA bases using two detection\nprinciples, namely, nanopore and nanoribbon modalities. We observe that binding\nenergies of DNA bases are lower in phosphorene compared to graphene. The energy\ngap modulations due to interaction with DNA bases are very significant in\nphosphorene compared to graphene. Our studies show that phosphorene is superior\nto graphene, and hence a promising alternative for electronic DNA sequencing.",
        "positive": "Linear optics, Raman scattering, and spin noise spectroscopy: Spin noise spectroscopy (SNS) is a new method for studying magnetic resonance\nand spin dynamics based on measuring the Faraday rotation noise. In strong\ncontrast with methods of nonlinear optics, the spectroscopy of spin noise is\nconsidered to be essentially nonperturbative. Presently, however, it became\nclear that the SNS, as an optical technique, demonstrates properties lying far\nbeyond the bounds of conventional linear optics. Specifically, the SNS shows\ndependence of the signal on the light power density, makes it possible to\npenetrate inside an inhomogeneously broadened absorption band and to determine\nits homogeneous width, allows one to realize an effective pump-probe\nspectroscopy without any optical nonlinearity, etc. This may seem especially\npuzzling when taken into account that SNS can be considered just as a version\nof Raman spectroscopy, which is known to be deprived of such abilities. In this\npaper, we clarify this apparent inconsistency."
    },
    {
        "anchor": "Hanbury Brown and Twiss Correlations of Cooper Pairs in Helical Liquids: We propose a Hanbury Brown and Twiss (HBT) experiment of Cooper pairs on the\nedge channels of quantum spin Hall insulators. The helical edge channels\nprovide a well defined beam of Cooper pairs and perfect Andreev reflections\nfrom superconductors. Surprisingly, the Cooper pairs do not bear a bosonic\nnature at all once emitted from the superconductor, and the cross correlation\nis strongly negative as for free electrons. This result is counter-intuitive,\nand seemingly contradictory to the previous theoretical and recent experimental\nresults. We will point out that our setup is much closer in spirit to the\noriginal HBT experiment (and different) than those in previous works. We will\nargue that these differences affect significantly the results.",
        "positive": "High-mobility AlAs quantum wells with out-of-plane valley occupation: Employing state-of-the-art molecular beam epitaxy techniques to grow thin,\nmodulation-doped AlAs quantum wells, we have achieved a low temperature\nmobility of 5.5 m$^2$/Vs with out-of-plane occupation, an order of magnitude\nimprovement over previous studies. However, due to the narrow well width,\nmobilities are still limited by scattering due to interface roughness disorder.\nWe demonstrate the successful implementation of a novel technique utilizing\nthermally-induced, biaxial, tensile strain that forces electrons to occupy the\nout-of-plane valley in thicker quantum wells, reducing interface roughness\nscattering and allowing us to achieve mobilities as high as 8.8 m$^2$/Vs."
    },
    {
        "anchor": "The fractional quantum Hall effect in infinite layer systems: Stacked two dimensional electron systems in transverse magnetic fields\nexhibit three dimensional fractional quantum Hall phases. We analyze the\nsimplest such phases and find novel bulk properties, e.g., irrational braiding.\nThese phases host ``one and a half'' dimensional surface phases in which motion\nin one direction is chiral. We offer a general analysis of conduction in the\nlatter by combining sum rule and renormalization group arguments, and find that\nwhen interlayer tunneling is marginal or irrelevant they are chiral semi-metals\nthat conduct only at T > 0 or with disorder.",
        "positive": "Off-axial focusing of spin-wave lens in the presence of\n  Dzyaloshinskii-Moriya interaction: We theoretically study the effect of Dzyaloshinskii-Moriya interaction (DMI)\non the focusing of a spin-wave lens that is constructed by a circular interface\nbetween two magnetic films. We analytically derive the generalized Snell's law\nin the curved geometry and the position of the focal point which exhibits a\npeculiar off-axial focusing behavior. We uncover a strong dependence of the\nfocal point on both the material parameters and the frequency of incident spin\nwaves. Full micromagnetic simulations compare well with theoretical\npredictions. Our findings would be helpful to manipulate spin waves in chiral\nmagnets and to design functional magnonic devices."
    },
    {
        "anchor": "Interaction mediated asymmetries of the quantized Hall effect: Experimental and theoretical investigations on the integer quantized Hall\neffect in gate defined narrow Hall bars are presented. At low electron mobility\nthe classical (high temperature) Hall resistance line RH(B) cuts through the\ncenter of all Hall plateaus. In contrast, for our high mobility samples the\nintersection point, at even filling factors \\nu = 2; 4 ..., is clearly shifted\ntowards larger magnetic fields B. This asymmetry is in good agreement with\npredictions of the screening theory, i. e. taking Coulomb interaction into\naccount. The observed effect is directly related to the formation of\nincompressible strips in the Hall bar. The spin-split plateau at \\nu= 1 is\nfound to be almost symmetric regardless of the mobility. We explain this within\nthe so-called effective g-model.",
        "positive": "Dynamic acousto-mechanical control of a strongly coupled photonic\n  molecule: Two-dimensional photonic crystal membranes provide a versatile planar\narchitecture for integrated photonics to control the propagation of light on a\nchip employing high quality optical cavities, waveguides, beamsplitters or\ndispersive elements. When combined with highly non-linear quantum emitters,\nquantum photonic networks operating at the single photon level come within\nreach. Towards large-scale quantum photonic networks, selective dynamic control\nof individual components and deterministic interactions between different\nconstituents are of paramount importance. This indeed calls for switching\nspeeds ultimately on the system's native timescales. For example, manipulation\nvia electric fields or all-optical means have been employed for switching in\nnanophotonic circuits and cavity quantum electrodynamics studies. Here, we\ndemonstrate dynamic control of the coherent interaction between two coupled\nphotonic crystal nanocavities forming a photonic molecule. By using an\nelectrically generated radio frequency surface acoustic wave we achieve\noptomechanical tuning, demonstrate operating speeds more than three orders of\nmagnitude faster than resonant mechanical approaches. Moreover, the tuning\nrange is large enough to compensate for the inherent fabrication-related cavity\nmode detuning. Our findings open a route towards nanomechanically gated\nprotocols, which hitherto have inhibited the realization in all-optical\nschemes."
    },
    {
        "anchor": "Charge-pseudospin coupled diffusion in semi-Dirac graphene: pseudospin\n  assisted valley transport: Modifying the hexagonal lattices of graphene enables the repositioning and\nmerging of the Dirac cones which proves to be a key element in the use of these\nmaterials for alternative electronic applications such as valleytronics. Here\nwe study the nonequilibrium transport of carriers within a system containing\ntwo Dirac cones in both standard graphene and semi-Dirac graphene. In the\nlatter, the lattice modifications cause the relativistic and parabolic\ndispersion bands to coexist, furnishing the Fermi surface with a rich\npseudospin texture and a versatile Dirac cones separation. We construct a\nkinetic theory to investigate the carrier diffusion and uncover that the\npseudospin index contributes to the particle current and, like the real spin,\ncan induce a magnetoelectric effect, and argue that the pseudospin-charge\ncoupling can be utilized to design a pseudospin filter. We explore the charge\ndynamics inside a quasi-one-dimensional conductor using the drift-diffusion\nmodel and detect the pseudospin accumulation at the sample boundaries. We find\nthat, while, for graphene, the accumulation contributes to an extra voltage\ndrop between the sample interfaces, the semi-Dirac system presents a similar\naccumulation that is strikingly equipped with valley polarization, signifying\nan essential tool for the control of valley manipulation and chirality\ntransport using the pseudospin.",
        "positive": "The origin of Raman D Band: Bonding and Antibonding Orbitals in Graphene: In Raman spectroscopy of graphite and graphene, the $D$ band at $\\sim\n1355$cm$^{-1}$ is used as the indication of the dirtiness of a sample. However,\nour analysis suggests that the physics behind the $D$ band is closely related\nto a very clear idea for describing a molecule, namely bonding and antibonding\norbitals in graphene. In this paper, we review our recent work on the mechanism\nfor activating the $D$ band at a graphene edge."
    },
    {
        "anchor": "Dirac quantum well engineering on the surface of topological insulator: We investigate a quantum well that consists of a thin topological insulator\nsandwiched between two trivial insulators. More specifically, we consider\nsmooth interfaces between these different types of materials such that the\ninterfaces host not only the chiral interface states, whose existence is\ndictated by the bulk-edge correspondence, but also massive Volkov-Pankratov\nstates. We investigate possible hybridization between these interface states as\na function of the width of the topological material and of the characteristic\ninterface size. Most saliently, we find a strong qualitative difference between\nan extremely weak effect on the chiral interface states and a more common\nhybridization of the massive Volkov-Pankratov states that can be easily\nunderstood in terms of quantum tunneling in the framework of the model of a\n(Dirac) quantum well we introduce here.",
        "positive": "Discontinuous current-phase relations in small 1D Josephson junction\n  arrays: We study the Josephson effect in small one-dimensional (1D) Josephson\njunction arrays. For weak Josephson tunneling, topologically different regions\nin the charge-stability diagram generate distinct current-phase relationships\n(I$\\Phi$). We present results for a three-junction system in the vicinity of\ncharge degeneracy lines and triple points. We explain the generalization to\nlarger arrays, show that discontinuities of the I$\\Phi$ at phase $\\pi$ persist\nand that, at maximum degeneracy, the problem can be mapped to a tight-binding\nmodel providing analytical results for arbitrary system size."
    },
    {
        "anchor": "Nonadiabatic single-qubit quantum Otto engine: According to Clausius formulation of the second law of thermodynamics, for\nany thermal machine withdrawing heats $Q_{1,2}$ from two heat reservoirs at\ntemperatures $T_{1,2}$, it holds $Q_1/T_1+Q_2/T_2 \\leq 0$. Combined with the\nobservation that the quantity $Q_1+Q_2$ is the work $W$ done by the system,\nthat inequality tells that only 4 possible operation modes are possible for the\nthermal machine, namely heat engine [E], refrigerator [R], thermal accelerator\n[A] and heater [H]. We illustrate their emergence in the finite time operation\nof a quantum Otto engine realised with a single qubit. We first focus on the\nideal case when isothermal and thermally-insulated strokes are well separated,\nand give general results as well as results pertaining to the specific\nfinite-time Landau-Zener dynamics. We then present realistic results pertaining\nto the solid-state experimental implementation proposed by Karimi and Pekola\n[Phys. Rev. B \\textbf{94} (2016) 184503]. That device is non-adiabatic both in\nthe quantum mechanical sense and in the thermodynamical sense. Oscillations in\nthe power extracted from the baths due to coherent LZ tunnelling at too low\ntemperatures are observed that might hinder the robustness of the operation of\nthe device against experimental noise on the control parameters.",
        "positive": "Compact description of quantum phase slip junctions: Quantum circuit theory is a powerful and ever-evolving tool to predict the\ndynamics of superconducting circuits. In its language, quantum phase slips\n(QPSs) are famously considered to be the exact dual to the Josephson effect.\nHowever, this duality renders the integration of QPS junctions into a unified\ntheoretical framework very difficult, and as we show, gives rise to serious\ninconsistencies for different formalisms, and in some cases difficulties to\ninclude time-dependent flux driving. We propose to resolve these issues by\nreducing and compactifying the Hilbert space describing the QPS processes. Our\ntreatment provides for the first time a unified description of the\nAharonov-Bohm and Aharonov-Casher effects, properly defines the valid form of\ninductive interactions to an environment, and allows to account for recent\ninsights on how to include electromotive forces. Finally, we show that the\ncompactification is likewise important for correctly predicting the available\ncomputational space for qubit architectures involving QPS junctions."
    },
    {
        "anchor": "Domain Wall Motion in Thin-Film Magnets/ Topological Insulator Junctions: We derive the equations of motion of a Domain Wall in a thin-film magnet\ncoupled to the surface states of a Topological Insulator in the presence of of\nboth an electric field along the Domain Wall and a magnetic field perpendicular\nto the junction. We show how the electric field acts as a chirality stabilizer\nholding off the appearance of Walker breakdown and enhancing the terminal\nvelocity. We also propose a mechanism to reverse the Domain Wall chirality in a\ncontrollable manner by tuning the chiral current flowing through the Wall. An\ninput from a weak perpendicular magnetic field is required in order to break\nthe reflection symmetry that protects the degeneracy of the chirality vacuum.",
        "positive": "Electric dipole induced universality for Dirac fermions in graphene: We study electric dipole effects for massive Dirac fermions in graphene and\nrelated materials. The dipole potential accomodates towers of infinitely many\nbound states exhibiting a universal Efimov-like scaling hierarchy. The dipole\nmoment determines the number of towers, but there is always at least one tower.\nThe corresponding eigenstates show a characteristic angular asymmetry,\nobservable in tunnel spectroscopy. However, charge transport properties\ninferred from scattering states are highly isotropic."
    },
    {
        "anchor": "Time-Resolved Imaging of Negative Differential Resistance on the Atomic\n  Scale: Negative differential resistance remains an attractive but elusive\nfunctionality, so far only finding niche applications. Atom scale entities have\nshown promising properties, but viability of device fabrication requires fuller\nunderstanding of electron dynamics than has been possible to date. Using an\nall-electronic time-resolved scanning tunneling microscopy technique and a\nGreen's function transport model, we study an isolated dangling bond on a\nhydrogen terminated silicon surface. A robust negative differential resistance\nfeature is identified as a many body phenomenon related to occupation dependent\nelectron capture by a single atomic level. We measure all the time constants\ninvolved in this process and present atomically resolved, nanosecond timescale\nimages to simultaneously capture the spatial and temporal variation of the\nobserved feature.",
        "positive": "Force-detected Nuclear Magnetic Resonance: The drive to improve the sensitivity of nuclear magnetic resonance (NMR) to\nsmaller and smaller sample volumes has led to the development of a variety of\ntechniques distinct from conventional inductive detection. In this chapter, we\nfocus on the technique of force-detected NMR as one of the most successful in\nyielding sensitivity improvements. We review the rationale for the technique,\nits basic principles, and give a brief history of its most important results.\nWe then cover in greater detail its application in the first demonstration of\nthree-dimensional (3D) nuclear magnetic resonance imaging (MRI) with\nnanometer-scale resolution. Next we present recent developments and likely\npaths for improvement. Finally, the technique and its potential are discussed\nin the context of competing and complementary technologies."
    },
    {
        "anchor": "Manipulating spin and charge in magnetic semiconductors\n  usingsuperconducting vortices: The continuous need for miniaturization and increase in device speed exerts\npressureon the electronics industry to explore new avenues of information\nprocessing. One possibility is to use the spin to store, manipulate and carry\ninformation. Indeed,spintronics may hold the promise of providing such a new\nparadigm. However, all spintronics applications are faced with formidable\nchallenges in attempting to find fastand efficient ways to create, transport,\ndetect, control and manipulate spin textures and currents. Here we show how\nmost of these operations can be performed in arelatively simple manner in a\nhybrid system consisting of a superconducting (SC) film and a paramagnetic\ndiluted magnetic semiconductor (DMS) quantum well (QW). Ourproposal is based on\nthe observation that the inhomogeneous magnetic fields of the SC create local\nspin and charge textures in the DMS, leading to effects such as\nBlochoscillations, an unusual Quantum Hall Effect, etc. We exploit the recent\nprogress in manipulating magnetic flux bundles (vortices) in superconductors\nand show howthese can create, manipulate and control the spin textures in DMS.",
        "positive": "Classical versus Quantum Transport near Quantum Hall Transitions: In attempt to settle the apparent disagreements between different\nexperimental results, transport data near quantum Hall transitions are\ninterpreted by identifying two distinct conduction regimes. The ``classical''\nregime, dominated by nearest neighbor hopping between localized conducting\npuddles, manifests an activated-like resistivity formula, and the quantized\nHall insulator behavior. At very low temperatures $T$, or farther from the\ncritical point, a crossover occurs to a \"quantum\" transport regime dominated by\nvariable range hopping. The latter is characterized by a different\nT-dependence, yet the dependence on filling fraction is, coincidentally, hard\nto distinguish."
    },
    {
        "anchor": "Conductance and Thermopower of Ballistic Andreev Cavities: When coupling a superconductor to a normal conducting region the physical\nproperties of the system are highly affected by the superconductor. We will\ninvestigate the effect of one or two superconductors on the conductance of a\nballistic chaotic quantum dot to leading order in the total channel number\nusing trajectory based semiclassics. The results show that the effect of one\nsuperconductor on the conductance is of the order of the number of channels and\nthat the sign of the correction from the Drude conductance depends on the\nparticular ratios of the numbers of channels of the superconducting and normal\nconducting leads. In the case of two superconductors with the same chemical\npotential we will also see how the conductance and the sign of quantum\ncorrections are affected by their phase difference. As far as random matrix\ntheory results exist these are reproduced by our calculations. Furthermore in\nthe case that the chemical potential of the superconductors is the same as that\nof one of the two normal leads the conductance shows, under certain conditions,\nsimilar effects as a normal metal-superconductor junction. The semiclassical\nframework is also able to treat the thermopower of chaotic Andreev billiards\nconsisting of one chaotic dot, two normal leads and two superconducting islands\nand shows it to be antisymmetric in the phase difference of the\nsuperconductors.",
        "positive": "A Thickness Dependent Enhancement of Optical Resolution in the Vicinity\n  of an Epsilon-near-zero Slab: Recent studies reports that an epsilon-near-zero (ENZ) thin slab between a\nspecimen and a substrate contributes in enhancing the spatial resolution of the\noptical system. Here, we investigate the ENZ thickness dependence of the\nresolution enhancement. By employing the edge response function, the resolution\nof the optical system is directly measured when imaging a sharp edge of a metal\nfilm. We found that the optimum ENZ slab thickness was 700 nm and the achieved\nresolution was 11 {\\mu}m at the wavelength of 8 {\\mu}m. Owing to the enhanced\nresolution by ENZ slab, we successfully imaged the subwavelength slit arrays."
    },
    {
        "anchor": "Scanning Gate Microscopy of Localized States in a gate-defined Bilayer\n  Graphene Channel: We use Scanning Gate Microscopy to demonstrate the presence of localized\nstates arising from potential inhomogeneities in a 50nm-wide, gate-defined\nconducting channel in encapsulated bilayer graphene. When imaging the channel\nconductance under the influence of a local tip-induced potential, we observe\nellipses of enhanced conductance as a function of the tip position. These\nellipses allow us to infer the location of the localized states and to study\ntheir dependence on the displacement field. For large displacement fields, we\nobserve that localized states tend to occur halfway into the channel. All our\nobservations can be well explained within the framework of stochastic Coulomb\nblockade.",
        "positive": "Magnetism in graphene nano-islands: We study the magnetic properties of nanometer-sized graphene structures with\ntriangular and hexagonal shapes terminated by zig-zag edges. We discuss how the\nshape of the island, the imbalance in the number of atoms belonging to the two\ngraphene sublattices, the existence of zero-energy states, and the total and\nlocal magnetic moment are intimately related. We consider electronic\ninteractions both in a mean-field approximation of the one-orbital Hubbard\nmodel and with density functional calculations. Both descriptions yield values\nfor the ground state total spin, $S$, consistent with Lieb's theorem for\nbipartite lattices. Triangles have a finite $S$ for all sizes whereas hexagons\nhave S=0 and develop local moments above a critical size of $\\approx 1.5$ nm."
    },
    {
        "anchor": "Revealing the nature of defects in quasi free standing mono-layer\n  graphene on SiC(0001) by means of Density Functional Theory: Quasi free standing monolayer graphene (QFMLG) grown on SiC by selective Si\nevaporation from the Si-rich SiC(0001) face and H intercalation displays\nirregularities in STM and AFM analysis, appearing as localized features, which\nwe previously identified as vacancies in the H layer coverage [Y Murata, et al.\nNano Res, in press, DOI: 10.1007/s12274-017-1697-x]. The size, shape,\nbrightness, location, and concentration of these features, however, are\nvariable, depending on the hydrogenation conditions. In order to shed light on\nthe nature of these features, in this work we perform a systematic Density\nFunctional Theory study on the structural and electronic properties of QFMLG\nwith defects in the H coverage arranged in different configurations including\nup to 13 vacant H atoms, and show that these generate localized electronic\nstates with specific electronic structure. Based on the comparison of simulated\nand measured STM images we are able to associate different vacancies of large\nsize (7-13 missing H) to the different observed features. The presence of large\nvacancies is in agreement with the tendency of single H vacancies to aggregate,\nas demonstrated here by DFT results. This gives some hints into the\nhydrogenation process. Our work unravels the structural diversity of defects of\nH coverage in QFMLG and provides operative ways to interpret the variety in the\nSTM images. The energy of the localized states generated by these vacancies is\ntunable by means of their size and shape, suggesting applications in nano- and\nopto-electronics.",
        "positive": "Nonlinear Thermal Properties of Three-Terminal Mesoscopic Dielectric\n  Systems: This paper studies the thermal properties of three-terminal mesoscopic\ndielectric systems in the nonlinear response regime at low temperature. For a\nsymmetric three-terminal system, when the temperature is finitely different\nbetween the left and right thermal reservoirs, the temperature of the central\nthermal reservoir is always higher than the averaging temperature of the\nothers. This nonlinear thermal phenomenon is also observed for asymmetric\nthree-terminal systems. At the end, a model of thermal rectification is\npresented."
    },
    {
        "anchor": "Range separated hybrid density functional study of organic dye\n  sensitizers on anatase TiO$_2$ nanowires: The adsorption of organic molecules coumarin and the donor-$\\pi$-acceptor\ntype tetrahydroquinoline (C2-1) on anatase (101) and (001) nanowires have been\ninvestigated using screened Coulomb hybrid density functional theory\ncalculations. While coumarin forms single bond with the nanowire surface, C2-1\nadditionally exhibits bidentate mode giving rise to much stronger adsorption\nenergies. Nonlinear solvation effects on the binding characteristics of the dye\nchromophores on the nanowire facets have also been examined. These two dye\nsensitizers show different electronic charge distributions for the highest\noccupied and the lowest unoccupied molecular states. We studied the electronic\nstructures in terms of the positions of the band edges and adsorbate related\nband gap states and their effect on the absorption spectra of the dye-nanowire\ncombined systems. These findings were interpreted and discussed from the view\npoint of better light harvesting and charge separation as well as in relation\nto more efficient charge carrier injection into the semiconductor nanowire.",
        "positive": "Photothermoelectric effects and large photovoltages in plasmonic Au\n  nanowires with nanogaps: Nanostructured metals subject to local optical interrogation can generate\nopen-circuit photovoltages potentially useful for energy conversion and\nphotodetection. We report a study of the photovoltage as a function of\nillumination position in single metal Au nanowires and nanowires with nanogaps\nformed by electromigration. We use a laser scanning microscope to locally heat\nthe metal nanostructures via excitation of a local plasmon resonance and direct\nabsorption. In nanowires without nanogaps, where charge transport is diffusive,\nwe observe voltage distributions consistent with thermoelectricity, with the\nlocal Seebeck coefficient depending on the width of the nanowire. In the\nnanowires with nanogaps, where charge transport is by tunneling, we observe\nlarge photovoltages up to tens of mV, with magnitude, polarization dependence,\nand spatial localization that follow the plasmon resonance in the nanogap. This\nis consistent with a model of photocurrent across the nanogap carried by the\nnonequilibrium, \"hot\" carriers generated upon the plasmon excitation."
    },
    {
        "anchor": "Unusual Resistance Hysteresis in n-Layer Graphene Field Effect\n  Transistors Fabricated on Ferroelectric Pb(Zr_0.2Ti_0.8)O_3: We have fabricated n-layer graphene field effect transistors on epitaxial\nferroelectric Pb(Zr_0.2Ti_0.8)O_3 (PZT) thin films. At low gate voltages, PZT\nbehaves as a high-k dielectric with k up to 100. An unusual resistance\nhysteresis occurs in gate sweeps at high voltages, with its direction opposite\nto that expected from the polarization switching of PZT. The relaxation of the\nmetastable state is thermally activated, with an activation barrier of 50-110\nmeV and a time constant of 6 hours at 300 K. We attribute its origin to the\nslow dissociation/recombination dynamics of water molecules adsorbed at the\ngraphene-PZT interface. This robust hysteresis can potentially be used to\nconstruct graphene-ferroelectric hybrid memory devices.",
        "positive": "Nanocavity optomechanical torque magnetometry and radiofrequency\n  susceptometry: Nanophotonic optomechanical devices allow observation of nanoscale vibrations\nwith sensitivity that has dramatically advanced metrology of nanomechanical\nstructures [1-9] and has the potential to impact studies of nanoscale physical\nsystems in a similar manner [10, 11]. Here we demonstrate this potential with a\nnanophotonic optomechanical torque magnetometer and radiofrequency (RF)\nmagnetic susceptometer. Exquisite readout sensitivity provided by a nanocavity\nintegrated within a torsional nanomechanical resonator enables observations of\nthe unique net magnetization and RF-driven responses of single mesoscopic\nmagnetic structures in ambient conditions. The magnetic moment resolution is\nsufficient for observation of Barkhausen steps in the magnetic hysteresis of a\nlithographically patterned permalloy island [12]. In addition, significantly\nenhanced RF susceptibility is found over narrow field ranges and attributed to\nthermally assisted driven hopping of a magnetic vortex core between neighboring\npinning sites [13]. The on-chip magneto-susceptometer scheme offers a promising\npath to powerful integrated cavity optomechanical devices for quantitative\ncharacterization of magnetic micro- and nanosystems in science and technology."
    },
    {
        "anchor": "Substrate limited electron dynamics in graphene: We study the effects of polarizable substrates such as SiO2 and SiC on the\ncarrier dynamics in graphene. We find that the quasiparticle spectrum acquires\na finite broadening due to the long-range interaction with the polar modes at\nthe interface between graphene and the substrate. This mechanism results in a\ndensity dependent electrical resistivity, that exhibits a sharp increase around\nroom temperature, where it can become the dominant limiting factor of electron\ntransport. The effects are weaker in doped bilayer graphene, due to the more\nconventional parabolic band dispersion.",
        "positive": "Static surface mode expansion for the full-wave scattering from\n  penetrable objects: We introduce the longitudinal and transverse static surface modes and use\nthem to solve the full-wave electromagnetic scattering problem from penetrable\nobjects. The longitudinal static modes are the eigenmodes with zero surface\ncurl of the electrostatic integral operator that gives the tangential component\nof the electric field, as a function of the surface charge density. The\ntransverse static modes are the eigenmodes with zero surface divergence of the\nmagnetostatic integral operator that returns the tangential component of the\nvector potential, as a function of the surface current distribution. The static\nmodes only depend on the shape of the object, thus, the same static basis can\nbe used regardless of the frequency of operation and of the material\nconstituting the object. We expand the unknown surface currents of the\nPoggio-Miller-Chang-Harrington-Wu-Tsai surface integral equations in terms of\nthe static surface modes and solve them using the Galerkin-projection scheme.\nThe static modes expansion allows the regularization of the singular integral\noperators and yields a drastic reduction of the number of unknowns compared to\na discretization based on sub-domain basis functions. The introduced expansion\nsignificantly reduces the cpu-time required for the numerical solution of the\nscattering problem from particle arrays."
    },
    {
        "anchor": "Bilayer graphene: gap tunability and edge properties: Bilayer graphene -- two coupled single graphene layers stacked as in graphite\n-- provides the only known semiconductor with a gap that can be tuned\nexternally through electric field effect. Here we use a tight binding approach\nto study how the gap changes with the applied electric field. Within a parallel\nplate capacitor model and taking into account screening of the external field,\nwe describe real back gated and/or chemically doped bilayer devices. We show\nthat a gap between zero and midinfrared energies can be induced and externally\ntuned in these devices, making bilayer graphene very appealing from the point\nof view of applications. However, applications to nanotechnology require\ncareful treatment of the effect of sample boundaries. This being particularly\ntrue in graphene, where the presence of edge states at zero energy -- the Fermi\nlevel of the undoped system -- has been extensively reported. Here we show that\nalso bilayer graphene supports surface states localized at zigzag edges. The\npresence of two layers, however, allows for a new type of edge state which\nshows an enhanced penetration into the bulk and gives rise to band crossing\nphenomenon inside the gap of the biased bilayer system.",
        "positive": "Reactive self-heating model of aluminum spherical nanoparticles: Aluminum-oxygen reaction is important in many highly energetic, high pressure\ngenerating systems. Recent experiments with nanostructured thermites suggest\nthat oxidation of aluminum nanoparticles occurs in a few microseconds. Such\nrapid reaction cannot be explained by a conventional diffusion-based mechanism.\nWe present a rapid oxidation model of a spherical aluminum nanoparticle, using\nCabrera-Mott moving boundary mechanism, and taking self-heating into account.\nIn our model, electric potential solves the nonlinear Poisson equation. In\ncontrast with the Coulomb potential, a \"double-layer\" type solution for the\npotential and self-heating leads to enhanced oxidation rates. At maximal\nreaction temperature of 2000 C, our model predicts overall oxidation time scale\nin microseconds range, in agreement with experimental evidence."
    },
    {
        "anchor": "Waiting time distribution revealing the internal spin dynamics in a\n  double quantum dot: Waiting time distribution and the zero-frequency full counting statistics of\nunidirectional electron transport through a double quantum dot molecule\nattached to spin-polarized leads are analyzed using the quantum master\nequation. The waiting time distribution exhibits a non-trivial dependence on\nthe value of the exchange coupling between the dots and the gradient of the\napplied magnetic field, which reveals the oscillations between the spin states\nof the molecule. The zero-frequency full counting statistics, on the other\nhand, is independent of the aforementioned quantities, thus giving no insight\ninto the internal dynamics. The fact that the waiting time distribution and the\nzero-frequency full counting statistics give a non-equivalent information is\nassociated with two factors. Firstly, it can be explained by the sensitivity to\ndifferent timescales of the dynamics of the system. Secondly, it is associated\nwith the presence of the correlation between subsequent waiting times, which\nmakes the renewal theory, relating the full counting statistics and the waiting\ntime distribution, not longer applicable. The study highlights the particular\nusefulness of the waiting time distribution for the analysis of the internal\ndynamics of mesoscopic systems.",
        "positive": "Relating the topology of Dirac Hamiltonians to quantum geometry: When\n  the quantum metric dictates Chern numbers and winding numbers: Quantum geometry has emerged as a central and ubiquitous concept in quantum\nsciences, with direct consequences on quantum metrology and many-body quantum\nphysics. In this context, two fundamental geometric quantities are known to\nplay complementary roles: the Fubini-Study metric, which introduces a notion of\ndistance between quantum states defined over a parameter space, and the Berry\ncurvature associated with Berry-phase effects and topological band structures.\nIn fact, recent studies have revealed direct relations between these two\nimportant quantities, suggesting that topological properties can, in special\ncases, be deduced from the quantum metric. In this work, we establish general\nand exact relations between the quantum metric and the topological invariants\nof generic Dirac Hamiltonians. In particular, we demonstrate that topological\nindices (Chern numbers or winding numbers) are bounded by the quantum volume\ndetermined by the quantum metric. Our theoretical framework, which builds on\nthe Clifford algebra of Dirac matrices, is applicable to topological insulators\nand semimetals of arbitrary spatial dimensions, with or without chiral\nsymmetry. This work clarifies the role of the Fubini-Study metric in\ntopological states of matter, suggesting unexplored topological responses and\nmetrological applications in a broad class of quantum-engineered systems."
    },
    {
        "anchor": "Spinless Hartree-Fock model of persistent current in rings with single\n  scatterer: Comparison with correlated models: Using the self-consistent Hartree-Fock approximation for spinless electrons\nat zero temperature, we study the persistent current of the interacting\nelectron gas in a one-dimensional continuous ring containing a single $\\delta$\nbarrier. We calculate the persistent current as a function of the ring\ncircumference, magnetic flux threading the ring, barrier strength, etc. We\ncompare our results with the results of correlated models like the Luttinger\nliquid model and the Hubbard model solved by means of the renormalization\ngroup. A good agreement is found. First, the persistent current decays with the\nincreasing ring circumference ($L$) faster than $L^{-1}$ and eventually like\n$L^{-\\alpha-1}$, where $\\alpha>0$ depends only on the electron-electron\ninteraction. Second, the persistent current is a sine-shaped function of\nmagnetic flux. This sine-like dependence and in particular the universal power\nlaw $L^{-\\alpha-1}$ have sofar been believed to arise only in the correlated\nmany-body models. Observation of these features within the Hartree-Fock model\nis a surprising result.",
        "positive": "A quadrupolar exchange-only spin qubit: We propose a quadrupolar exchange-only spin (QUEX) qubit that is highly\nrobust against charge noise and nuclear spin dephasing, the dominant\ndecoherence mechanisms in quantum dots. The qubit consists of four electrons\ntrapped in three quantum dots, and operates in a decoherence-free subspace to\nmitigate dephasing due to nuclear spins. To reduce sensitivity to charge noise,\nthe qubit can be completely operated at an extended charge noise sweet spot\nthat is first-order insensitive to electrical fluctuations. Due to on-site\nexchange mediated by the Coulomb interaction, the qubit energy splitting is\nelectrically controllable and can amount to several GHz even in the ``off\"\nconfiguration, making it compatible with conventional microwave cavities."
    },
    {
        "anchor": "Ring current effects on the dielectric function of cylindrical\n  nano-organic materials: We review recent results on the behaviour of the dielectric function of\ncylindrical nano-organic materials at very low frequencies in a magnetic field.\nFor cylindrical structures - such as carbon nanotubes - the polarisability is\nshown to be a discontinuous function of a longitudinal magnetic field where\nplateau-like regions are separated by sudden jumps or peaks. A relation is\npointed out between each discontinuity in the polarisability and the cross-over\nbetween ground and first excited states induced by the magnetic field. This one\nto one correspondence suggests to use measurements of the dielectric function\nin an applied magnetic field in order to obtain informations about the\nelectronic structures of cylindrical nanostructures. In addition, it is shown,\nby studying finite graphene layers, that the measurement of the polarisability\nin a magnetic field could be a powerful way for detecting possible edge-states\nin amorphous carbon materials such as activated carbon fibres. Finally, the\nimportance of the electron-electron interaction is emphasised by discussing\nexamples of strongly interacting electrons on rings or cylinders, in the limit\nof infinite interaction.",
        "positive": "Robust one-dimensional wires in lattice mismatched bilayer graphene: We show that lattice mismatched bilayer graphene can realize robust\none-dimensional wires. By considering a single domain wall where the masses of\nthe Dirac electrons change their sign, we establish a general projection\nprinciple. This determines how the existence of topological zero-energy domain\nwall states depends on the direction of the domain wall and locations of the\nmassive Dirac cones inside the bulk Brillouin zone. We generalize this idea for\narbitrary patterns of domain walls, showing that the topologically protected\nstates exist only in the presence of an odd number of topological domain walls."
    },
    {
        "anchor": "Theory of Spin Relaxation in Two-Electron Lateral Coupled Si/SiGe\n  Quantum Dots: Highly accurate numerical results of phonon-induced two-electron spin\nrelaxation in silicon double quantum dots are presented. The relaxation,\nenabled by spin-orbit coupling and the nuclei of $^{29}$Si (natural or purified\nabundance), are investigated for experimentally relevant parameters, the\ninterdot coupling, the magnetic field magnitude and orientation, and the\ndetuning. We calculate relaxation rates for zero and finite temperatures (100\nmK), concluding that our findings for zero temperature remain qualitatively\nvalid also for 100 mK. We confirm the same anisotropic switch of the axis of\nprolonged spin lifetime with varying detuning as recently predicted in GaAs.\nConditions for possibly hyperfine-dominated relaxation are much more stringent\nin Si than in GaAs. For experimentally relevant regimes, the spin-orbit\ncoupling, although weak, is the dominant contribution, yielding anisotropic\nrelaxation rates of at least two order of magnitude lower than in GaAs.",
        "positive": "Attractive and repulsive dipolar interaction in bilayers of indirect\n  excitons: We explore attractive dipolar interaction in indirect excitons (IXs). For one\nlayer of IXs in a single pair of coupled quantum wells (CQW), the out-of-plane\nIX electric dipoles lead to repulsive dipolar interaction between IXs. The\nattractive dipolar interaction between IXs is realized in a 2-CQW\nheterostructure with two IX layers in two separated CQW pairs. We found both in\nexperimental measurements and theoretical simulations that increasing density\nof IXs in one layer causes a monotonic energy reduction for IXs in the other\nlayer. We also found an in-plane shift of a cloud of IXs in one layer towards a\ncloud of IXs in the other layer. This behaviour is qualitatively consistent\nwith attractive dipolar interaction. The measured IX energy reduction and IX\ncloud shift are higher than the values given by the correlated liquid theory."
    },
    {
        "anchor": "Multi-level effects in quantum-dot based parity-to-charge conversion of\n  Majorana box qubits: Quantum-dot based parity-to-charge conversion is a promising method for\nreading out quantum information encoded nonlocally into pairs of Majorana zero\nmodes. To obtain a sizable parity-to-charge visibility, it is crucial to tune\nthe relative phase of the tunnel couplings between the dot and the Majorana\nmodes appropriately. However, in the presence of multiple quasi-degenerate dot\norbitals, it is in general not experimentally feasible to tune all couplings\nindividually. This paper shows that such configurations could make it difficult\nto avoid a destructive multi-orbital interference effect that substantially\nreduces the read-out visibility. We analyze this effect using a Lindblad\nquantum master equation. This exposes how the experimentally relevant system\nparameters enhance or suppress the visibility when strong charging energy,\nmeasurement dissipation and, most importantly, multi-orbital interference is\naccounted for. In particular, we find that an intermediate-time readout could\nmitigate some of the interference-related visibility reductions affecting the\nstationary limit.",
        "positive": "Non-linear antidamping spin-orbit torque originating from intra-band\n  transport on the warped surface of a topological insulator: Motivated by recent experiments observing a large antidamping spin-orbit\ntorque (SOT) on the surface of a three-dimensional topological insulator, we\ninvestigate the origin of the current-induced SOT beyond linear-response\ntheory. We find that a strong antidamping SOT arises from intraband transitions\nin non-linear response, and does not require interband transitions as is the\ncase in linear transport mechanisms. The joint effect of warping and an\nin-plane magnetization generates a non-linear antidamping SOT which can exceed\nthe intrinsic one by several orders of magnitude, depending on warping\nparameter and the position of Fermi energy, and exhibits a complex dependence\non the azimuthal angle of the magnetization. This nonlinear SOT provides an\nalternative explanation of the observed giant SOT in recent experiments."
    },
    {
        "anchor": "Nuclear magnetism and electron order in interacting one-dimensional\n  conductors: The interaction between localized magnetic moments and the electrons of a\none-dimensional conductor can lead to an ordered phase in which the magnetic\nmoments and the electrons are tightly bound to each other. We show here that\nthis occurs when a lattice of nuclear spins is embedded in a Luttinger liquid.\nExperimentally available examples of such a system are single wall carbon\nnanotubes grown entirely from 13C and GaAs-based quantum wires. In these\nsystems the hyperfine interaction between the nuclear spin and the conduction\nelectron spin is very weak, yet it triggers a strong feedback reaction that\nresults in an ordered phase consisting of a nuclear helimagnet that is\ninseparably bound to an electronic density wave combining charge and spin\ndegrees of freedom. This effect can be interpreted as a strong renormalization\nof the nuclear Overhauser field and is a unique signature of Luttinger liquid\nphysics. Through the feedback the order persists up into the millikelvin range.\nA particular signature is the reduction of the electric conductance by the\nuniversal factor 2.",
        "positive": "Nonequilibrium mesoscopic conductance fluctuations: We investigate the amplitude of mesoscopic fluctuations of the differential\nconductance of a metallic wire at arbitrary bias voltage V. For non-interacting\nelectrons, the variance <delta g^2> increases with V. The asymptotic large-V\nbehavior is <delta g^2> \\sim V/V_c (where eV_c=D/L^2 is the Thouless energy),\nin agreement with the earlier prediction by Larkin and Khmelnitskii. We find,\nhowever, that this asymptotics has a very small numerical prefactor and sets in\nat very large V/V_c only, which strongly complicates its experimental\nobservation. This high-voltage behavior is preceded by a crossover regime,\nV/V_c \\lesssim 30, where the conductance variance increases by a factor \\sim 3\nas compared to its value in the regime of universal conductance fluctuations\n(i.e., at V->0). We further analyze the effect of dephasing due to the\nelectron-electron scattering on <delta g^2> at high voltages. With the Coulomb\ninteraction taken into account, the amplitude of conductance fluctuations\nbecomes a non-monotonic function of V. Specifically, <delta g^2> drops as 1/V\nfor voltages V >> gV_c, where g is the dimensionless conductance. In this\nregime, the conductance fluctuations are dominated by quantum-coherent regions\nof the wire adjacent to the reservoirs."
    },
    {
        "anchor": "Exciton-Coupled Coherent Magnons in a 2D Semiconductor: Two-dimensional (2D) magnetic semiconductors feature both tightly-bound\nexcitons with large oscillator strength and potentially long-lived coherent\nmagnons due to the presence of bandgap and spatial confinement. While magnons\nand excitons are energetically mismatched by orders of magnitude, their\ncoupling can lead to efficient optical access to spin information. Here we\nreport strong magnon-exciton coupling in the 2D van der Waals (vdW)\nantiferromagnetic (AFM) semiconductor CrSBr. Coherent magnons launched by\nabove-gap excitation modulate the interlayer hybridization, which leads to\ndynamic modulation of excitonic energies. Time-resolved exciton sensing reveals\nmagnons that can coherently travel beyond 7 micrometer, with coherence time\nabove 5 ns. We observe this exciton-coupled coherent magnons in both even and\nodd number of layers, with and without compensated magnetization, down to the\nbilayer limit. Given the versatility of vdW heterostructures, these coherent 2D\nmagnons may be basis for optically accessible magnonics and quantum\ninterconnects.",
        "positive": "Microwave studies of the fractional Josephson effect in HgTe-based\n  Josephson junctions: The rise of topological phases of matter is strongly connected to their\npotential to host Majorana bound states, a powerful ingredient in the search\nfor a robust, topologically protected, quantum information processing. In order\nto produce such states, a method of choice is to induce superconductivity in\ntopological insulators. The engineering of the interplay between\nsuperconductivity and the electronic properties of a topological insulator is a\nchallenging task and it is consequently very important to understand the\nphysics of simple superconducting devices such as Josephson junctions, in which\nnew topological properties are expected to emerge. In this article, we review\nrecent experiments investigating topological superconductivity in topological\ninsulators, using microwave excitation and detection techniques. More\nprecisely, we have fabricated and studied topological Josephson junctions made\nof HgTe weak links in contact with two Al or Nb contacts. In such devices, we\nhave observed two signatures of the fractional Josephson effect, which is\nexpected to emerge from topologically-protected gapless Andreev bound states.\nWe first recall the theoretical background on topological Josephson junctions,\nthen move to the experimental observations. Then, we assess the topological\norigin of the observed features and conclude with an outlook towards more\nadvanced microwave spectroscopy experiments, currently under development."
    },
    {
        "anchor": "First order phase transitions driven by in-plane magnetic field in\n  odd-integral quantum Hall bilayer electron systems: This paper has been withdrawn by the author.",
        "positive": "Measurements of cyclotron resonance of the interfacial states in strong\n  spin-orbit coupled 2D electron gases proximitized with aluminum: Two-dimensional electron gasses (2DEG) in InAs quantum wells proximitized by\naluminum are promising platforms for topological qubits based on Majorana zero\nmodes. However, there are still substantial uncertainties associated with the\nnature of the electronic states at the interfaces of these systems. It is\nchallenging to probe the properties of these hybridized states as they are\nburied under a relatively thick aluminum layer. In this work, we have\ninvestigated a range of InAs/In$ _{1-\\text{x}} $Ga$ _\\text{x} $As\nheterostructures with Al overlayers using high precision time-domain THz\nspectroscopy. Despite the thick metallic overlayer, we observe a prominent\ncyclotron resonance in the magnetic field that can be associated with the\nresponse of the interfacial states. Measurements of the THz range complex\nFaraday rotation allow the extraction of the sign and magnitude of the\neffective mass, the density of charge carriers, and scattering times of the\n2DEG despite the close proximity of the aluminum layer. We discuss the\nextracted band parameters and connect their values to the known physics of\nthese materials."
    },
    {
        "anchor": "Remote plasmon--induced heat transfer probed by the electronic transport\n  of a gold nanowire: We show in this paper that the heat generated by the optical excitation of\nresonant plasmonic antennas and diffusing along a simple glass/air interface\ndisturbs the electron transport of a nearby conductive element. By probing the\ntemperature-dependent resistance of a gold nanowire $R_{\\rm nw}(T)$, we\nquantitatively analyze the impact of a resonant absorption of the laser by the\nantennas. We find that the temperature rise at the nanowire induced by the\nlaser absorption of a distant nanoparticle may exceed that of a direct\nillumination of the nanowire itself. We also find that a global temperature\ncalibration underestimates the heat generated locally by the laser. The\ntemperature deduced from resistance variations are verified by numerical\nsimulations with a very satisfactory agreement.",
        "positive": "Dike states in multiple quantum dots: We present a theoretical study of the collective optical effects which can\noccur in groups of three and four quantum dots. We define conditions for stable\nsubradiant (dark) states, rapidly decaying superradiant states,and spontaneous\ntrapping of excitation. Each quantum dot is treated like a two-level system.\nThe quantum dots are though realistic, meaning that they may have different\ntransition energies and dipole moments. The dots interact via a short-range\ncoupling which allows excitation transfer across the dots, but conserves the\ntotal population. We calculate the time evolution of single- and biexciton\nstates using the Linblad equation. In the steady state the individual\npopulations of each dot may have permanent oscillations with frequencies given\nby the energy separation between the subradiant eigenstates."
    },
    {
        "anchor": "Effects of Mismatch Strain and Substrate Surface Corrugation on\n  Morphology of Supported Monolayer Graphene: Graphene monolayers supported on oxide substrates have been demonstrated with\nsuperior charge mobility and thermal transport for potential device\napplications. Morphological corrugation can strongly influence the transport\nproperties of the supported graphene. In this paper, we theoretically analyze\nthe morphological stability of a graphene monolayer on an oxide substrate,\nsubject to van der Waals interactions and in-plane mismatch strains. First, we\ndefine the equilibrium separation and the interfacial adhesion energy as the\ntwo key parameters that characterize the van der Waals interaction between a\nflat monolayer and a flat substrate surface. By a perturbation analysis, a\ncritical compressive mismatch strain is predicted, beyond which the graphene\nmonolayer undergoes strain-induced instability, forming corrugations with\nincreasing amplitude and decreasing wavelength on a perfectly flat surface.\nWhen the substrate surface is not perfectly flat, the morphology of graphene\ndepends on both the amplitude and the wavelength of the surface corrugation. A\ntransition from conformal (corrugated) to non-conformal (flat) morphology is\npredicted. The effects of substrate surface corrugation on the equilibrium mean\nthickness of the supported graphene and the interfacial adhesion energy are\nanalyzed. Furthermore, by considering both the substrate surface corrugation\nand the mismatch strain, it is found that, while a tensile mismatch strain\nreduces the corrugation amplitude of graphene, a corrugated substrate surface\npromotes strain-induced instability under a compressive strain. These\ntheoretical results suggest possible means to control the morphology of\ngraphene monolayer on oxide substrates by surface patterning and strain\nengineering.",
        "positive": "Spin accumulation in the spin Nernst effect: The spin Nernst effect is a phenomenon in which the spin current flows\nperpendicular to a temperature gradient. Similar to the spin Hall effect, this\nphenomenon also causes spin accumulation at the boundaries. Here, we study the\nspin response to the gradient of the temperature gradient with the use of\nGreen's functions. Our formalism predicts physically observable spin\naccumulation without the ambiguity regarding the definition of the spin current\nor the magnetization correction. We prove the generalized Mott relation between\nthe electric and thermal responses assuming the presence of time-reversal\nsymmetry and the absence of inelastic scattering. We also find that thermal\nspin accumulation vanishes for the three-dimensional Luttinger model but is\nnonzero for the two-dimensional Rashba model with $\\delta$-function nonmagnetic\ndisorder in the first Born approximation."
    },
    {
        "anchor": "Impact of thermal fluctuations on transport in antiferromagnetic\n  semimetals: Recent demonstrations on manipulating antiferromagnetic (AF) order have\ntriggered a growing interest in antiferromagnetic metal (AFM), and potential\nhigh-density spintronic applications demand further improvements in the\nanisotropic magnetoresistance (AMR). The antiferromagnetic semimetals (AFS) are\nnewly discovered materials that possess massless Dirac fermions that are\nprotected by the crystalline symmetries. In this material, a reorientation of\nthe AF order may break the underlying symmetries and induce a finite energy\ngap. As such, the possible phase transition from the semimetallic to insulating\nphase gives us a choice for a wide range of resistance ensuring a large AMR. To\nfurther understand the robustness of the phase transition, we study thermal\nfluctuations of the AF order in AFS at a finite temperature. For macroscopic\nsamples, we find that the thermal fluctuations effectively decrease the\nmagnitude of the AF order by renormalizing the effective Hamiltonian. Our\nfinding suggests that the insulating phase exhibits a gap narrowing at elevated\ntemperatures, which leads to a substantial decrease in AMR. We also examine\nspatially correlated thermal fluctuations for microscopic samples by solving\nthe microscopic Landau-Lifshitz-Gilbert equation finding a qualitative\ndifference of the gap narrowing in the insulating phase. For both cases, the\nsemimetallic phase shows a minimal change in its transmission spectrum\nillustrating the robustness of the symmetry protected states in AFS. Our\nfinding may serve as a guideline for estimating and maximizing AMR of the AFS\nsamples at elevated temperatures.",
        "positive": "Universality of Many-Body States in Rotating Bose and Fermi Systems: We propose a universal transformation from a many-boson state to a\ncorresponding many-fermion state in the lowest Landau level approximation of\nrotating many-body systems, inspired by the Laughlin wave function and by the\nJain composite-fermion construction. We employ the exact-diagonalization\ntechnique for finding the many-body states. The overlap between the transformed\nboson ground state and the true fermion ground state is calculated in order to\nmeasure the quality of the transformation. For very small and high angular\nmomenta, the overlap is typically above 90%. For intermediate angular momenta,\nmixing between states complicates the picture and leads to small ground-state\noverlaps at some angular momenta."
    },
    {
        "anchor": "Evidence for the S=9 excited state in Mn12-bromoacetate measured by\n  electron paramagnetic resonance: We present high-frequency high-field electron paramagnetic resonance (EPR)\nmeasurements on the dodecanuclear manganese complex Mn12-bromoacetate\n(Mn12-BrAc). The crystal-field parameters are found to be identical to those of\nthe original compound Mn12-acetate (Mn12-Ac). A detailed analysis of the\nfrequency and temperature dependence of anomalous peaks observed in the EPR\nspectra of Mn12-BrAc enables us to locate the S=9 manifold at about 40 K above\nthe Ms= +/-10 ground state of this nominally S=10 system. This is very close to\nthe Ms = +/-6 state of the S = 10 manifold, thus suggesting pathways for the\nthermally assisted magnetization dynamics and related properties. Finally, the\nEPR fine structures recently attributed to disorder associated with the acetic\nacid of crystallization in Mn12-Ac are absent in the present measurements, thus\nsuggesting that the Mn12-BrAc complex represents a more suitable candidate for\nmeasurements of quantum effects in high symmetry S=10 SMMs.",
        "positive": "Statistical analysis of the shape of one-dimensional nanostructures:\n  determining the coalescence degree of spontaneously formed GaN nanowires: Single GaN nanowires formed spontaneously on a given substrate represent\nnanoscopic single crystals free of any extended defects. However, due to the\nhigh area density of thus formed GaN nanowire ensembles, individual nanowires\ncoalesce with others in their immediate vicinity. This coalescence process may\nintroduce strain and structural defects, foiling the idea of defect-free\nmaterial due to the nanowire geometry. To investigate the consequences of this\nprocess, a quantitative measure of the coalescence of nanowire ensembles is\nrequired. We derive objective criteria to determine the coalescence degree of\nGaN nanowire ensembles. These criteria are based on the area-perimeter\nrelationship of the cross-sectional shapes observed, and in particular on their\ncircularity. Employing these criteria, we distinguish single nanowires from\ncoalesced aggregates in an ensemble, determine the diameter distribution of\nboth, and finally analyze the coalescence degree of nanowire ensembles with\nincreasing fill factor."
    },
    {
        "anchor": "Dirac and Normal Fermions in Graphite and Graphene: Implications to the\n  Quantum Hall Effect: Spectral analysis of Shubnikov de Haas (SdH) oscillations of\nmagnetoresistance and of Quantum Hall Effect (QHE) measured in quasi-2D highly\noriented pyrolytic graphite (HOPG) [Phys. Rev. Lett. 90, 156402 (2003)] reveals\ntwo types of carriers: normal (massive) electrons with Berry phase 0 and\nDirac-like (massless) holes with Berry phase pi. We demonstrate that recently\nreported integer- and semi-integer QHE for bi-layer and single-layer graphenes\ntake place simultaneously in HOPG samples.",
        "positive": "Spin-injection Hall effect in a planar photovoltaic cell: Successful incorporation of the spin degree of freedom in semiconductor\ntechnology requires the development of a new paradigm allowing for a scalable,\nnon-destructive electrical detection of the spin-polarization of injected\ncharge carriers as they propagate along the semiconducting channel. In this\npaper we report the observation of a spin-injection Hall effect (SIHE) which\nexploits the quantum-relativistic nature of spin-charge transport and which\nmeets all these key requirements on the spin detection. The two-dimensional\nelectron-hole gas photo-voltaic cell we designed to observe the SIHE allows us\nto develop a quantitative microscopic theory of the phenomenon and to\ndemonstrate its direct application in optoelectronics. We report an\nexperimental realization of a non-magnetic spin-photovoltaic effect via the\nSIHE, rendering our device an electrical polarimeter which directly converts\nthe degree of circular polarization of light to a voltage signal."
    },
    {
        "anchor": "Chemical potential of quasi-equilibrium magnon gas driven by pure spin\n  current: We show experimentally that the spin current generated by the spin Hall\neffect drives the magnon gas in a ferromagnet into a quasi-equilibrium state\nthat can be described by the Bose-Einstein statistics. The magnon population\nfunction is characterized either by an increased effective chemical potential\nor by a reduced effective temperature, depending on the spin current\npolarization. In the former case, the chemical potential can closely approach,\nat large driving currents, the lowest-energy magnon state, indicating the\npossibility of spin current-driven Bose-Einstein condensation.",
        "positive": "Decoherence of nuclear spins due to direct dipole-dipole interactions\n  probed by resistively detected nuclear magnetic resonance: We study decoherence of nuclear spins in a GaAs quantum well structure using\nresistively detected nuclear magnetic resonance. The transverse decoherence\ntime T2 of 75As nuclei is estimated from Rabi-type coherent oscillations as\nwell as by using spin-echo techniques. By analyzing T2 obtained by decoupling\ntechniques, we extract the role of dipole-dipole interactions as sources of\ndecoherence in GaAs. Under the condition that the device is tilted in an\nexternal magnetic field, we exhibit enhanced decoherence induced by the change\nin strength of the direct dipole-dipole interactions between first\nnearest-neighbor nuclei. The results agree well with simple numerical\ncalculations."
    },
    {
        "anchor": "The Hall effect in ballistic flow of two-dimensional interacting\n  particles: In high-quality solid-state systems at low temperatures, the hydrodynamic or\nthe ballistic regimes of heat and charge transport are realized in the electron\nand the phonon systems. In these regimes, the thermal and the electric\nconductance of the sample can reach abnormally large magnitudes. In this paper,\nwe study the Hall effect in a system of interacting two-dimensional charged\nparticles in a ballistic regime. We demonstrated that the Hall electric field\nis caused by a change in the densities of particles due to the effect of\nexternal fields on their free motions between the sample edges. In\none-component (electron or hole) systems the Hall coefficient turns out to one\nhalf compared with the one in conventional disordered Ohmic samples. This\nresult is consistent with the recent experiment on measuring of the Hall\nresistance in ultra-high-mobility GaAs quantum wells. In two-component\nelectron-hole systems the Hall electric field depends linearly on the\ndifference between the concentrations of electrons and holes near the charge\nneutrality point (the equilibrium electron and hole densities coincide) and\nsaturates to the Hall field of a one-component system far from the charge\nneutrality point. We also studied the corrections to magnetoresistance and the\nHall electric field due to inter-particle scattering being a precursor of\nforming a viscous flow. For the samples shorter than the inter-particle\nscattering length, the obtained corrections govern the dependencies of\nmagnetoresistance and the Hall field on temperature.",
        "positive": "The effect of valley, spin and band nesting on the electronic properties\n  of gated quantum dots in a single layer of transition metal dichalcogenides\n  (TMDCs): We present here results of atomistic theory of electrons confined by metallic\ngates in a single layer of transition metal dichalcogenides. The electronic\nstates are described by the tight-binding model and computed using a\ncomputational box including up to million atoms with periodic boundary\nconditions and parabolic confining potential due to external gates embedded in\nit. With this methodology applied to MoS2, we find a twofold degenerate energy\nspectrum of electrons confined in the two non-equivalent K-valleys by the\nmetallic gates as well as six-fold degenerate spectrum associated with\nQ-valleys. We compare the electron spectrum with the energy levels of electrons\nconfined in GaAs/GaAlAs and in self-assembled quantum dots. We discuss the role\nof spin splitting and topological moments on the K and Q valley electronic\nstates in quantum dots with sizes comparable to experiment."
    },
    {
        "anchor": "Parametric resonance in tunable superconducting cavities: We develop a theory of parametric resonance in tunable superconducting\ncavities. The nonlinearity introduced by the SQUID attached to the cavity, and\ndamping due to connection of the cavity to a transmission line are taken into\nconsideration. We study in detail the nonlinear classical dynamics of the\ncavity field below and above the parametric threshold for the degenerate\nparametric resonance, featuring regimes of multistability and parametric\nradiation. We investigate the phase-sensitive amplification of external signals\non resonance, as well as amplification of detuned signals, and relate the\namplifier performance to that of linear parametric amplifiers. We also discuss\napplications of the device for dispersive qubit readout. Beyond the classical\nresponse of the cavity, we investigate small quantum fluctuations around the\namplified classical signals. We evaluate the noise power spectrum both for the\ninternal field in the cavity and the output field. Other quantum statistical\nproperties of the noise are addressed such as squeezing spectra, second order\ncoherence, and two-mode entanglement.",
        "positive": "Fabry-P\u00e9rot resonances and a crossover to the quantum Hall regime in\n  ballistic graphene quantum point contacts: We report on the observation of quantum transport and interference in a\ngraphene device that is attached with a pair of split gates to form an\nelectrostatically-defined quantum point contact (QPC). In the low magnetic\nfield regime, the resistance exhibited Fabry-P\\'erot (FP) resonances due to\nnp'n (pn'p) cavities formed by the top gate. In the quantum Hall (QH) regime\nwith a high magnetic field, the edge states governed the phenomena, presenting\na unique condition where the edge channels of electrons and holes along a p-n\njunction acted as a solid-state analogue of a monochromatic light beam. We\nobserved a crossover from the FP to QH regimes in ballistic graphene QPC under\na magnetic field with varying temperatures. In particular, the collapse of the\nQH effect was elucidated as the magnetic field was decreased. Our high-mobility\ngraphene device enabled observation of such quantum coherence effects up to\nseveral tens of kelvins. The presented device could serve as one of the key\nelements in future electronic quantum optic devices."
    },
    {
        "anchor": "Bulk-boundary correspondence of topological insulators from their\n  Green's functions: Topological insulators are noninteracting, gapped fermionic systems which\nhave gapless boundary excitations. They are characterized by topological\ninvariants, which can be written in many different ways, including in terms of\nGreen's functions. Here we show that the existence of the edge states directly\nfollows from the existence of the topological invariant written in terms of the\nGreen's functions, for all ten classes of topological insulators in all spatial\ndimensions. We also show that the resulting edge states are characterized by\ntheir own topological invariant, whose value is equal to the topological\ninvariant of the bulk insulator. This can be used to test whether a given model\nHamiltonian can describe an edge of a topological insulator. Finally, we\nobserve that the results discussed here apply equally well to interacting\ntopological insulators, with certain modifications.",
        "positive": "Single-shot initialization of electron spin in a quantum dot using a\n  short optical pulse: We propose a technique to initialize an electron spin in a semiconductor\nquantum dot with a single short optical pulse. It relies on the fast depletion\nof the initial spin state followed by a preferential, Purcell-accelerated\ndesexcitation towards the desired state thanks to a micropillar cavity. We\ntheoretically discuss the limits on initialization rate and fidelity, and\nderive the pulse area for optimal initialization. We show that spin\ninitialization is possible using a single optical pulse down to a few tens of\npicoseconds wide."
    },
    {
        "anchor": "Nonlocal Drag Thermoelectricity Generated by Ferroelectric\n  Heterostructures: The \\textquotedblleft ferron\\textquotedblright\\ excitations of the\nelectric-dipolar order carry energy as well as electric dipoles. Here we\npredict a nonlocal ferron drag effect in a ferroelectric on top of a metallic\nfilm: An electric current in the conductor generates a heat current in the\nferroelectric by long-range charge-dipole interactions. The non-local Peltier\nand its reciprocal Seebeck effect can be controlled by electric gates and\ndetected thermographically. We predict large effects for van der Waals\nferroelectric films on graphene.",
        "positive": "Nonmonotonic charge occupation in double dots: We study the occupation of two electrostatically-coupled single-level quantum\ndots with spinless electrons as a function of gate voltage. While the total\noccupation of the double-dot system varies monotonically with gate voltage, we\npredict that the competition between tunneling and Coulomb interaction can give\nrise to a nonmonotonic filling of the individual quantum dots. This\nnon-monotonicity is a signature of the correlated nature of the many-body\nwavefunction in the reduced Hilbert space of the dots. We identify two\nmechanisms for this nonmonotonic behavior, which are associated with changes in\nthe spectral weights and the positions, respectively, of the excitation spectra\nof the individual quantum dots. An experimental setup to test these predictions\nis proposed."
    },
    {
        "anchor": "Ground-state energy of the electron liquid in ultrathin wires: The ground-state energy and the density correlation function of the electron\nliquid in a thin one-dimensional wire are computed. The calculation is based on\nan approximate mapping of the problem with a realistic Coulomb interaction law\nonto exactly solvable models of mathematical physics. This approach becomes\nasymptotically exact in the limit of small wire radius but remains numerically\naccurate even for modestly thin wires.",
        "positive": "Supercurrent in the quantum Hall regime: A novel promising route for creating topological states and excitations is to\ncombine superconductivity and the quantum Hall (QH) effect. Despite this\npotential, signatures of superconductivity in the quantum Hall regime remain\nscarce, and a superconducting current through a QH weak link has so far eluded\nexperimental observation. Here we demonstrate the existence of a new type of\nsupercurrent-carrying states in a QH region at magnetic fields as high as\n2Tesla. The observation of supercurrent in the quantum Hall regime marks an\nimportant step in the quest for exotic topological excitations such as Majorana\nfermions and parafermions, which may find applications in fault-tolerant\nquantum computations."
    },
    {
        "anchor": "Effect of van-Hove singularities in single-walled carbon nanotube leads\n  on transport through double quantum dot system: The double quantum dot system with single-walled metallic armchair carbon\nnanotube leads has been studied using Non-equilibrium Green function in the\nKeldysh formalism. The effect of relative spacing between the energy levels of\nthe dots, interdot tunneling matrix-element, interdot Coulomb interaction and\nvan-Hove singularities in density of states characteristics of\nquasi-one-dimensional carbon nanotube leads on the conductance of the double\nquantum dot system has been studied. The conductance and dot occupancies are\ncalculated at finite temperature. It is observed that the density of states of\nthe carbon nanotube leads play a significant role in determining the\nconductance profile. In particular, whenever the chemical potential of the\nisolated double quantum dot system is aligned with the position of a van-Hove\nsingularity in the density of states of armchair carbon nanotube leads, the\nheight of the corresponding conductance peak falls considerably. It is further\nobserved that the suppression in the heights of the alternate peaks depends on\nthe relative positions of the energy levels of the dots and their magnitude of\nseparation.",
        "positive": "Underscreened Kondo impurities in a Luttinger liquid: We study the problem of underscreened Kondo physics in an interacting\nelectronic system modeled by a Luttiger Liquid (LL). We find that the leading\ntemperature dependence of thermodynamical quantities like the specific heat,\nspin susceptibility are Fermi Liquid like in nature. However, anomalous power\nlaw exponents are seen in the subleading terms. We also discuss possible\nrealizations through single and double quantum dot configurations coupled to LL\nleads and its consequences for electronic transport. The leading low\ntemperature transport behavior is seen to exhibit in general, non Fermi liquid\nLL behavior unlike the thermodynamical quantities."
    },
    {
        "anchor": "Cyclotron Resonance Assisted Photocurrents in Surface States of a 3D\n  Topological Insulator Based on a Strained High Mobility HgTe Film: We report on the observation of cyclotron resonance induced photocurrents,\nexcited by continuous wave terahertz radiation, in a 3D topological insulator\n(TI) based on an 80 nm strained HgTe film. The analysis of the photocurrent\nformation is supported by complimentary measurements of magneto-transport and\nradiation transmission. We demonstrate that the photocurrent is generated in\nthe topologically protected surface states. Studying the resonance response in\na gated sample we examined the behavior of the photocurrent, which enables us\nto extract the mobility and the cyclotron mass as a function of the Fermi\nenergy. For high gate voltages we also detected cyclotron resonance (CR) of\nbulk carriers, with a mass about two times larger than that obtained for the\nsurface states. The origin of the CR assisted photocurrent is discussed in\nterms of asymmetric scattering of TI surface carriers in the momentum space.\nFurthermore, we show that studying the photocurrent in gated samples provides a\nsensitive method to probe the effective masses and the mobility of 2D Dirac\nsurface states, when the Fermi level lies in the bulk energy gap or even in the\nconduction band.",
        "positive": "Resonant high harmonic generation in a ballistic graphene transistor\n  with an AC driven gate: We report a theoretical study of time-dependent transport in a ballistic\ngraphene field effect transistor. We develop a model based on Floquet theory\ndescribing Dirac electron transmission through a harmonically driven potential\nbarrier. Photon-assisted tunneling results in excitation of quasibound states\nat the barrier. Under resonance condition, the excitation of the quasibound\nstates leads to promotion of higher-order sidebands and enhanced higher\nharmonics of the source-drain conductance. The resonances in the main\ntransmission channel are of the Fano form, while they are of the Breit-Wigner\nform for sidebands. We discuss the possibility of utilizing the resonances in\nprospective ballistic high-frequency devices, in particular frequency\nmultipliers."
    },
    {
        "anchor": "Large spin accumulation voltages in epitaxial Mn5Ge3 contacts on Ge\n  without oxide tunnel barrier: Spin injection in high-quality epitaxial Mn5Ge3 Schottky contacts on n-type\nGe has been investigated using a three-terminal Hanle effect measurement. Clear\nHanle and inverted Hanle signals with features characteristic of spin\naccumulation and spin precession are observed up to 200 K. Strikingly, the\nobserved spin voltage is several orders of magnitude larger than predicted by\nthe theory of spin injection and diffusive spin transport. Since the devices\nhave no oxide tunnel barrier, the discrepancy between theory and experiments\ncannot be explained by the often-invoked spin accumulation in localized states\nassociated with the oxide or oxide/semiconductor interface. The observed spin\nvoltages therefore must originate from the Ge itself, either from spins in the\nGe bulk bands or its depletion region.",
        "positive": "Radius-Voltage Relation of Graphene Bubbles Controlled by Gate Voltage: Graphene on the substrate can form bubbles rising above the sheet. In some\ncases, the bubble is a perfect spherical surface crown, and its radius can be\nadjusted by external electric field. In this manuscript, we theoretically\ninvestigate the voltage dependence of the spherical bubble's radius. The\ncalculated results are in good agreement with recent experiments on the\ngraphene bubble controlled by applied gate voltage [Appl. Phys. Lett. 99,\n093103 (2011)]."
    },
    {
        "anchor": "Strongly-bound excitons and trions in anisotropic 2D semiconductors: Monolayer and few-layer phosphorene are anisotropic quasi-two-dimensional\n(quasi-2D) van der Waals (vdW) semiconductors with a linear-dichroic\nlight-matter interaction and a widely-tunable direct-band gap in the infrared\nfrequency range. Despite recent theoretical predictions of strongly-bound\nexcitons with unique properties, it remains experimentally challenging to probe\nthe excitonic quasiparticles due to the severe oxidation during device\nfabrication. In this study, we report observation of strongly-bound excitons\nand trions with highly-anisotropic optical properties in intrinsic bilayer\nphosphorene, which are protected from oxidation by encapsulation with hexagonal\nboron nitride (hBN), in a field-effect transistor (FET) geometry. Reflection\ncontrast and photoluminescence spectroscopy clearly reveal the linear-dichroic\noptical spectra from anisotropic excitons and trions in the hBN-encapsulated\nbilayer phosphorene. The optical resonances from the exciton Rydberg series\nindicate that the neutral exciton binding energy is over 100 meV even with the\ndielectric screening from hBN. The electrostatic injection of free holes\nenables an additional optical resonance from a positive trion (charged exciton)\n~ 30 meV below the optical bandgap of the charge-neutral system. Our work shows\nexciting possibilities for monolayer and few-layer phosphorene as a platform to\nexplore many-body physics and novel photonics and optoelectronics based on\nstrongly-bound excitons with two-fold anisotropy.",
        "positive": "Interacting like charges in Landau levels: Planar geometry, symmetries,\n  and effective quasiparticles: We consider a system of two interacting particles with like but unequal\ncharges in a magnetic field in the planar geometry. We construct a complete\nbasis of states compatible with both the axial symmetry and magnetic\ntranslations. The basis is obtained using a canonical transformation that\ngenerates effective quasiparticles with modified interactions. We establish a\nconnection of this transformation with the SU(2) algebra and make use of the\nSU(2) Baker-Campbell-Hausdorff formulas for evaluating the interaction matrix\nelements. We calculate analytically the eigenenergies of the problem (Haldane\npseudopotentials) in the first few Landau levels for a relatively wide class of\ninteraction potentials."
    },
    {
        "anchor": "The Berry phase in frustrated spin glass: In this letter we have pointed out that frustration in spin glass is realized\nthrough the Berry phase due to the conflict between the spin ordering in the\ncourse of parallel transport of spinor. We have came to the point that the\nBerry phase depicting the chiral change of helicity of a quantized spinor is\nprominent only in the presence of frustration.",
        "positive": "Localization property of a periodic chain of atoms with aperiodically\n  coupled quantum dots: The spectral landscape and the transport property of a translationally\ninvariant network with side-coupled quantum dots are demonstrated within the\ntight-binding framework. For periodic environment band structure is\ndemonstrated analytically in details. Moreover, if the side-coupling here\nfollows a typical quasiperiodic Aubry-Andre-Harper type of modulation then such\noff-diagonal disorder invites an exotic spectral feature for this model quantum\nsystem. We perform an in-depth numerical analysis followed by the evaluation of\nthe density of eigenstates and the inverse participation ratio. The description\nshows that this network creates a typical self-similar kind of multifractal\npattern in the energy landscape. The impacts of the strength of such aperiodic\nconnectivity and the slowness parameter are reported in this analysis. In the\npresent era of advanced technology and lithography techniques all such\nnon-trivial results definitely throw an achievable challenge to the\nexperimentalists to study the localization of excitation in such network"
    },
    {
        "anchor": "Klein Bound States in Single-Layer Graphene: The Klein paradox, first introduced in relation to chiral tunneling, is also\nmanifested in the study of bound-states in single-layer graphene with a 1D\nsquare-well potential. We derive analytic (and numerical) solutions for\nbound-state wavefunctions, in the absence and in the presence of an external\ntransverse magnetic field, and calculate the corresponding dipole transition\nrates, which can be probed by photon absorption experiments. The role of parity\nand time-reversal symmetries is briefly discussed. Our results are also\nrelevant for the physics of bound states of light in periodic optical waveguide\nstructures.",
        "positive": "Mobility gap in fractional quantum Hall liquids: Effects of disorder and\n  layer thickness: We study the behavior of two-dimensional electron gas in the fractional\nquantum Hall regime in the presence of finite layer thickness and correlated\ndisordered potential. Generalizing the Chern number calculation to many-body\nsystems, we determine the mobility gaps of fractional quantum Hall states based\non the distribution of Chern numbers in a microscopic model. We find excellent\nagreement between experimentally measured activation gaps and our calculated\nmobility gaps, when combining the effects of both disordered potential and\nlayer thickness. We clarify the difference between mobility gap and spectral\ngap of fractional quantum Hall states and explain the disorder-driven collapse\nof the gap and the subsequent transitions from the fractional quantum Hall\nstates to insulator."
    },
    {
        "anchor": "Inducing anisotropies in Dirac fermions by periodic driving: We consider the three-dimensional Hamiltonian for Bi$_2$Se$_3$, a\nsecond-generation topological insulator, under the effect of a periodic drive\nfor both in-plane and out-of-plane fields. As it will be shown by means of\nhigh-frequency expansions up to second order in the Floquet Hamiltonian, the\ndriving induces anisotropies in the Dirac cone and opens up a quasienergy gap\nfor in-plane elliptically polarized fields. Analytic expressions are obtained\nfor the renormalized velocities and the quasienergy gap. These expressions are\nthen compared to numerical calculations performed by discretizing the\nHamiltonian in a one-dimensional lattice and following a staggered fermion\napproach, achieving a remarkable agreement. We believe our work may have an\nimpact on the transport properties of topological insulators.",
        "positive": "Anomalous low-temperature magnetoelastic properties of nanogranular\n  (CoFeB)$_{x}$-(SiO$_{2}$)$_{1-x}$: We report magnetostatic measurements for granulated films\n(CoFeB)$_{x}$-(SiO$_{2}$)$_{1-x}$ with fabrication induced intraplanar\nanisotropy. The measurements have been performed in the film plane in the wide\ntemperature interval 4.5$\\div$300 K. They demonstrate that above films have\nlow-temperature anomaly below the percolation threshold for conductivity. The\nessence of the above peculiarity is that below 100 K the temperature dependence\nof coercive field for magnetization along easy direction deviates strongly from\nNeel-Brown law. At temperature lowering, the sharp increase of coercivity is\nobserved, accompanied by the appearance of coercive field for magnetization\nalong hard direction in the film plane. We establish that observed effect is\nrelated to the properties of individual ferromagnetic granules. The effect\nweakens as granules merge into conglomerates at $x$ higher then percolation\nthreshold and disappears completely at $x>1$. We explain the above effect as a\nconsequence of the difference in thermal expansion coefficients of granule and\ncover material. At temperature lowering this difference weakens the envelopment\nof an individual granule by the cover matrix material, thus permitting to\nrealize the spontaneous magnetostriction of a granule. The latter induces an\nadditional anisotropy with new easy axis of a granule magnetization along the\nexternal magnetic field direction. Our explanation is tested and corroborated\nby the ferromagnetic resonance measurements in the films at $T$ = 300 K and $T$\n= 77 K."
    },
    {
        "anchor": "Spectral determinant on quantum graphs: We study the spectral determinant of the Laplacian on finite graphs\ncharacterized by their number of vertices V and of bonds B. We present a path\nintegral derivation which leads to two equivalent expressions of the spectral\ndeterminant of the Laplacian either in terms of a V x V vertex matrix or a 2B x\n2B link matrix that couples the arcs (oriented bonds) together. This latter\nexpression allows us to rewrite the spectral determinant as an infinite product\nof contributions of periodic orbits on the graph. We also present a\ndiagrammatic method that permits us to write the spectral determinant in terms\nof a finite number of periodic orbit contributions. These results are\ngeneralized to the case of graphs in a magnetic field. Several examples\nillustrating this formalism are presented and its application to the\nthermodynamic and transport properties of weakly disordered and coherent\nmesoscopic networks is discussed.",
        "positive": "Temperature dependence of the resistance switching effect studied on the\n  metal/YBa2Cu3O6+x planar junctions: Resistive switching (RS) effect observed in capacitor-like\nmetal/insulator/metal junctions belongs to the most promising candidates for\nnext generation of memory cell technology. It is based upon a sudden change of\nthe junction resistance caused by an electric field applied to the metal\nelectrodes. The aim of this work was to study this effect on the structure\nmetal/YBCO6/YBCO7, where YBCO7 is a metallic phase and YBCO6 is an insulator\nphase which arises spontaneously by out-diffusion of oxygen from a few\nnanometers wide YBCO surface layer. Oriented YBa2Cu3O7 thin films were prepared\nby the method of magnetron sputtering and consequently planar structures with\nmetal-YBCO junction were made by the means of the optical lithography, ion\netching and vacuum evaporation. On these junctions we have studied the\ntemperature dependence of the RS effect with I-V and dI/dV-V transport\nmeasurements down to liquid He temperature. We have determined temperature\ndependence of the RS effect threshold voltage in the temperature range 100-300\nK and showed that this dependency is compatible with common idea of oxygen ions\nmigration under electric field within the YBCO surface layer."
    },
    {
        "anchor": "Exciton condensation in quantum wells. Exciton hydrodynamics. The effect\n  of localized states: The hydrodynamic equations for indirect excitons in the double quantum wells\nare studied taking into account 1) a possibility of an exciton condensed phase\nformation, 2) the presence of pumping, 3) finite value of the exciton lifetime,\n4) exciton scattering by defects. The threshold pumping emergence of the\nperiodical exciton density distribution is found. The role of localized and\nfree exciton states is analyzed in the formation of emission spectra.",
        "positive": "Typical skyrmions versus bimerons: a long-distance competition in\n  ferromagnetic racetracks: During the last years, topologically protected collective modes of the\nmagnetization have called much attention. Among these, skyrmions and merons\nhave been the object of intense study. In particular, topological skyrmions are\nobjects with an integer skyrmion number $Q$ while merons have a half-integer\nskyrmion charge $q$. In this work, we consider a $Q=1$ skyrmion, composed by a\nmeron and an antimeron (bimeron), displacing in a ferromagnetic racetrack,\ndisputing a long-distance competition with its more famous counterpart, the\ntypical $Q=1$ cylindrically symmetrical skyrmion. Both types of topological\nstructures induce a Magnus force and then are subject to the Hall effect. The\ninfluence of the Dzyaloshinskii-Moriya interaction ($DMI$) present in certain\nmaterials and able to induces $DMI$-skyrmions is also analyzed. Our main aim is\nto compare the motions (induced by a spin-polarized current) of these objects\nalong with their own specific racetracks. We also investigate some favorable\nfactors which are able to give breath to the competitors, impelling them to\nremain in the race for longer distances before their annihilation at the\nracetrack lateral border. An interesting result is that the $DMI$-skyrmion\nloses this hypothetical race due to its larger rigidity."
    },
    {
        "anchor": "Frequencies of the Edge-Magnetoplasmon Excitations in Gated Quantum Hall\n  Edges: We have investigated microwave transmission through the edge of quantum Hall\nsystems by employing a coplanar waveguide (CPW) fabricated on the surface of a\nGaAs/AlGaAs two-dimensional electron gas (2DEG) wafer. An edge is introduced to\nthe slot region of the CPW by applying a negative bias $V_\\mathrm{g}$ to the\ncentral electrode (CE) and depleting the 2DEG below the CE. We observe peaks\nattributable to the excitation of edge magnetoplasmons (EMP) at a fundamental\nfrequency $f_0$ and at its harmonics $i f_0$ ($i$ = 2, 3,...). The frequency\n$f_0$ increases with decreasing $V_\\mathrm{g}$, indicating that EMP propagates\nwith higher velocity for more negative $V_\\mathrm{g}$. The dependence of $f_0$\non $V_\\mathrm{g}$ is interpreted in terms of the variation in the distance\nbetween the edge state and the CE, which alters the velocity by varying the\ncapacitive coupling between them. The peaks are observed to continue, albeit\nwith less clarity, up to the regions of $V_\\mathrm{g}$ where 2DEG still remains\nbelow the CE.",
        "positive": "First-principles study on the Li storage performance of silicon clusters\n  and graphene composite structure: This paper focuses on the performance of the storage of Li and the stability\nof the hybrid structure of different lattice planes of the silicon clusters and\ngraphene by the first-principle theory. In this paper, we calculate the binding\nenergy, adsorption energy and PDOS of the hybrid structure of the different\nheight and size of the silicon clusters and graphene. We figure out that there\ncan form strong Si-C bonds between the silicon cluster and graphene.\nEspecially, the hybrid structure of the silicon clusters with plane (111) and\ngraphene performs best with the highest formation energy and the outstanding\nstability. According to the calculation of Li absorption energy, we conclude\nthat the location of the silicon cluster near the graphene has higher\npossibility and higher absorption energy of the Li storage, with the reason\nthat the charge transfer between the lithium and the carbon and the silicon.\nBecause of the graphene used, the deformation of the interface of the silicon\nclusters can be obviously reduced during the absorption of Li, which brings\nabout a good future for the hybrid structure using for the battery anode\nmaterials."
    },
    {
        "anchor": "Cross-correlations mediated by Majorana bound states: We consider the correlated parallel transport through two quantum dots which\nare tunnel-coupled to the ends of a semiconductor nanowire where the Majorana\nbound states (MBSs) may emerge under proper conditions. In terms of the\ncross-correlation of currents, we reveal unusual behaviors originated from the\nnonlocal MBSs, including such as the distinct symmetry and antisymmetry of the\nspectral density in response to the dot-level modulations, and the vanished\ncross correlation occurred when any of the dot-levels is in resonance with the\nMajorana zero mode.",
        "positive": "Collective Excitations of Rotating Dipolar Fermi Gases in the Fractional\n  Quantum Hall Regime: We apply the magneto-roton theory of the fractional quantum Hall effect to\nstudy the collective excitation spectrum of rotating dipolar Fermi gases. The\npredicted spectrum has a finite energy gap in the long wavelength limit and a\nroton minimum at finite wave vector. The roton minimum being deepened from\nfilling factor 1/3 to filling factor 1/5 is a signature of incipient\ncrystallization near filling factor 1/7. We also demonstrate that there are no\nlow-lying single-particle excitations below the roton mode. The\nfractional-quantum-Hall fluid rotating dipolar fermions behaves as an\nincompressible superfluid at low temperature."
    },
    {
        "anchor": "Spin Coherence and Echo Modulation of the Silicon Vacancy in 4H-SiC at\n  Room Temperature: The silicon vacancy in silicon carbide is a strong emergent candidate for\napplications in quantum information processing and sensing. We perform room\ntemperature optically-detected magnetic resonance and spin echo measurements on\nan ensemble of vacancies and find the properties depend strongly on magnetic\nfield. The spin echo decay time varies from less than 10 $\\mu$s at low fields\nto 80 $\\mu$s at 68 mT, and a strong field-dependent spin echo modulation is\nalso observed. The modulation is attributed to the interaction with nuclear\nspins and is well-described by a theoretical model.",
        "positive": "Test of the Atiyah-Singer Index Theorem for Fullerene with a\n  Superconducting Microwave Resonator: Experiments have been performed using a spherical superconducting microwave\nresonator that simulates the geometric structure of the C60 fullerene molecule.\nThe objective was to study with very high resolution the exceptional spectral\nproperties emerging from the symmetries of the icosahedral structure of the\ncarbon lattice. In particular, the number of zero modes has been determined to\ntest the predictions of the Atiyah-Singer index theorem, which relates it to\nthe topology of the curved carbon lattice. This is, to the best of our\nknowledge, the first experimental verification of the index theorem."
    },
    {
        "anchor": "Spontaneous emission of phonons by coupled quantum dots: We find an interference effect for electron-phonon interactions in coupled\nsemiconductor quantum dots that can dominate the nonlinear transport properties\neven for temperatures close to zero. The intradot electron tunnel process leads\nto a `shake up' of the phonon system and is dominated by a double-slit-like\ninterference effect of spontaneously emitted phonons. The effect is closely\nrelated to subradiance of photons (Dicke effect) in a laser-trapped two-ion\nsystem and explains the oscillations in the nonlinear current-voltage\ncharacteristics of coupled dots observed recently.",
        "positive": "Tuning exciton and biexciton transition energies and fine structure\n  splitting through hydrostatic pressure in single InGaAs quantum dots: We demonstrate that the exciton and biexciton emission energies as well as\nexciton fine structure splitting (FSS) in single (In,Ga)As/GaAs quantum dots\n(QDs) can be efficiently tuned using hydrostatic pressure in situ in an optical\ncryostat at up to 4.4 GPa. The maximum exciton emission energy shift was up to\n380 meV, and the FSS was up to 180 $\\mu$eV. We successfully produced a\nbiexciton antibinding-binding transition in QDs, which is the key experimental\ncondition that generates color- and polarization-indistinguishable photon pairs\nfrom the cascade of biexciton emissions and that generates entangled photons\nvia a time-reordering scheme. We perform atomistic pseudopotential calculations\non realistic (In,Ga)As/GaAs QDs to understand the physical mechanism underlying\nthe hydrostatic pressure-induced effects."
    },
    {
        "anchor": "Trion induced negative photoconductivity in monolayer MoS2: Optical excitation typically enhances electrical conduction and low-frequency\nradiation absorption in semiconductors. We have, however, observed a pronounced\ntransient decrease of conductivity in doped monolayer molybdenum disulfide\n(MoS2), a two-dimensional (2D) semiconductor, under femtosecond laser\nexcitation. In particular, the conductivity is reduced dramatically down to\nonly 30% of its equilibrium value with high pump fluence. This anomalous\nphenomenon arises from the strong many-body interactions in the system, where\nphotoexcited electron-hole pairs join the doping-induced charges to form\ntrions, bound states of two electrons and one hole. The resultant increase of\nthe carrier effective mass substantially diminishes the carrier conductivity.",
        "positive": "Localized interlayer complexes in heterobilayer transition metal\n  dichalcogenides: We present theoretical results for the radiative rates and doping-dependent\nphotoluminescence spectrum of interlayer excitonic complexes localized by donor\nimpurities in MoSe$_2$/WSe$_2$ twisted heterobilayers, supported by quantum\nMonte Carlo calculations of binding energies and wave-function overlap\nintegrals. For closely aligned layers, radiative decay is made possible by the\nmomentum spread of the localized complexes' wave functions, resulting in few\n$\\mu$s$^{-1}$ radiative rates. For strongly misaligned layers, the short-range\ninteraction between the carriers and impurity provides a finite radiative rate\nwith a strong asymptotic twist angle dependence $\\propto \\theta^{-8}$. Finally,\nphonon-assisted recombination is considered, with emission of optical phonons\nin both layers resulting in additional weaker emission lines, redshifted by the\nphonon energy."
    },
    {
        "anchor": "Fractional flux periodicity in tori made of square lattice: This paper describes a study on fractional flux periodicity of the ground\nstate in planar systems made from a square lattice whose boundary is compacted\ninto a torus. It is pointed out that, in the long length and large diameter\nlimit of a torus, the ground-state energy and persistent currents show a\nfractional period of the fundamental unit of magnetic flux depending on the\ntwist around the torus axis. We discuss the possible relationship between the\ntwist and genus of a torus, and comment on fractional flux periodicity in a\ncylinder.",
        "positive": "Electronic Transport Properties of the Ising Quantum Hall Ferromagnet in\n  a Si Quantum Well: Magnetotransport properties are investigated for a high mobility Si two\ndimensional electron systems in the vicinity of a Landau level crossing point.\nAt low temperatures, the resistance peak having a strong anisotropy shows large\nhysteresis which is attributed to Ising quantum Hall ferromagnetism. The peak\nis split into two peaks in the paramagnetic regime. A mean field calculation\nfor the peak positions indicates that electron scattering is strong when the\npseudospin is partially polarized. We also study the current-voltage\ncharacteristics which exhibit a wide voltage plateau."
    },
    {
        "anchor": "Electronic properties of monolayer and bilayer graphene: The tight-binding model of electrons in graphene is reviewed. We derive\nlow-energy Hamiltonians supporting massless Dirac-like chiral fermions and\nmassive chiral fermions in monolayer and bilayer graphene, respectively, and we\ndescribe how their chirality is manifest in the sequencing of plateaus observed\nin the integer quantum Hall effect. The opening of a tuneable band gap in\nbilayer graphene in response to a transverse electric field is described, and\nwe explain how Hartree theory may be used to develop a simple analytical model\nof screening.",
        "positive": "Topology and entanglement in quench dynamics: We classify the topology of quench dynamics by homotopy groups. A relation\nbetween the topological invariant of a post-quench order parameter and the\ntopological invariant of a static Hamiltonian is shown in one, two and three\ndimensions. The mid-gap states in the entanglement spectrum of the post-quench\nstate reveal its topological nature. When a trivial quantum state under a\nsudden quench to a Chern insulator, the mid-gap states in entanglement spectrum\nform rings. These rings are analogous to the boundary Fermi rings in the Hopf\ninsulators. Finally, we show a post-quench state in 3+1 dimensions can be\ncharacterized by the second Chern number. The number of Dirac cones in the\nentanglement spectrum is equal to the second Chern number."
    },
    {
        "anchor": "Caustics due to Negative Refractive Index in Circular Graphene p-n\n  Junctions: We show that the wavefunctions form caustics in circular graphene p-n\njunctions which in the framework of geometrical optics can be interpreted with\nnegative refractive index.",
        "positive": "Absorption in atomic wires: The transfer matrix formalism is implemented in the form of the multiple\ncollision technique to account for dissipative transmission processes by using\ncomplex potentials in several models of atomic chains. The absorption term is\nrigorously treated to recover unitarity for the non-hermitian hamiltonians. In\ncontrast to other models of parametrized scatterers we assemble explicit\npotentials profiles in the form of delta arrays, Poschl-Teller holes and\ncomplex Scarf potentials. The techniques developed provide analytical\nexpressions for the scattering and absorption probabilities of arbitrarily long\nwires. The approach presented is suitable for modelling molecular aggregate\npotentials and also supports new models of continuous disordered systems. The\nresults obtained also suggest the possibility of using these complex potentials\nwithin disordered wires to study the loss of coherence in the electronic\nlocalization regime due to phase-breaking inelastic processes."
    },
    {
        "anchor": "Quasiparticle trapping at vortices producing Josephson supercurrent\n  enhancement: The Josephson junction of a strong spin-orbit material under a magnetic field\nis a promising Majorana fermion candidate.\n  Supercurrent enhancement by a magnetic field has been observed in the InAs\nnanowire Josephson junctions and assigned to a topological transition. In this\nwork we observe a similar phenomenon but discuss the non-topological origin by\nconsidering trapping of quasiparticles by vortices that penetrate the\nsuperconductor under a finite magnetic field. This assignment is supported by\nthe observed hysteresis of the switching current when sweeping up and down the\nmagnetic field. Our experiment shows the importance of quasiparticles in\nsuperconducting devices with a magnetic field, which can provide important\ninsights for the design of quantum qubits using superconductors.",
        "positive": "Imbert-Fedorov shift in pseudospin-$N/2$ semimetals and nodal-line\n  semimetals: The Imbert-Fedorov (IF) shift is the transverse shift of a beam at a surface\nor an interface. It is a manifestation of the three-component Berry curvature\nin three dimensions, and has been studied in optical systems and Weyl\nsemimetals. Here we investigate the IF shift in two types of topological\nsystems, topological semimetals with pseudospin-$N/2$ for an arbitrary integer\n$N$, and nodal-line semimetals (NLSMs). For the former, we find the IF shift\ndepends on the components of the pseudospin, with the sign depending on the\nchirality. We term this phenomenon the pseudospin Hall effect of topological\nfermions. The shift can also be interpreted as a consequence of the\nconservation of the total angular momentum. For the latter, if the NLSM has\nboth time-reversal and inversion symmetries, the IF shift is zero; otherwise it\ncould be finite. We take the NLSM with a vortex ring, which breaks both\nsymmetries, as an example, and show that the IF shift can be used to detect\ntopological Lifshitz transitions. Finally, we propose experimental designs to\ndetect the IF shift."
    },
    {
        "anchor": "Spin-orbit related power-law dependence of the diffusive conductivity on\n  the carrier density in disordered Rashba two-dimensional electron systems: By using the momentum-space Lanczos recursive method which considers\nrigorously all multiple-scattering events, we unveil that the non-perturbative\ndisorder effect has dramatic impact on the charge transport of a\ntwo-dimensional electron system with Rashba spin-orbit coupling in the\nlow-density region. Our simulations find a power-law dependence of the dc\nlongitudinal conductivity on the carrier density, with the exponent linearly\ndependent on the Rashba spin-orbit strength but independent of the disorder\nstrength. Therefore, the classical charge transport influenced by complicated\nmultiple-scattering processes also shows the characteristic feature of the\nspin-orbit coupling. This highly unconventional behavior is argued to be\nobservable in systems with tunable carrier density and Rashba splitting, such\nas the LaAlO$_{3}$/SrTiO$_{3}$ interface, the heterostructure of Rashba\nsemiconductors bismuth tellurohalides and the surface alloy\nBi$_x$Pb$_y$Sb$_{1-x-y}$/Ag(111).",
        "positive": "Dynamical bi-stability of single-molecule junctions: A combined\n  experimental/theoretical study of PTCDA on Ag(111): The dynamics of a molecular junction consisting of a PTCDA molecule between\nthe tip of a scanning tunneling microscope and a Ag(111) surface have been\ninvestigated experimentally and theoretically. Repeated switching of a PTCDA\nmolecule between two conductance states is studied by low-temperature scanning\ntunneling microscopy for the first time, and is found to be dependent on the\ntip-substrate distance and the applied bias. Using a minimal model Hamiltonian\napproach combined with density-functional calculations, the switching is shown\nto be related to the scattering of electrons tunneling through the junction,\nwhich progressively excite the relevant chemical bond. Depending on the\ndirection in which the molecule switches, different molecular orbitals are\nshown to dominate the transport and thus the vibrational heating process. This\nin turn can dramatically affect the switching rate, leading to non-monotonic\nbehavior with respect to bias under certain conditions. In this work, rather\nthan simply assuming a constant density of states as in previous works, it was\nmodeled by Lorentzians. This allows for the successful description of this\nnon-monotonic behavior of the switching rate, thus demonstrating the importance\nof modeling the density of states realistically."
    },
    {
        "anchor": "Band structures of strained Kagome lattices: Materials with kagome lattice have attracted significant research attention\ndue to their nontrivial features in energy bands. In this work, we\ntheoretically investigate the evolution of electronic band structures of kagome\nlattice in response to uniaxial strain using both a tight-binding model and an\nantidot model based on a periodic muffin-tin potential. It is found that the\nDirac points move with applied strain. Furthermore, the flat band of unstrained\nkagome lattice is found to develop into a highly anisotropic shape under a\nstretching strain along y direction, forming a partially flat band with a\nregion dispersionless along ky direction while dispersive along kx direction.\nOur results shed light on the possibility of engineering the electronic band\nstructures of kagome materials by mechanical strain.",
        "positive": "Dark-exciton based strain sensing in transition metal dichalcogenides: The trend towards ever smaller high-performance devices in modern technology\nrequires novel materials with new functionalities. The recent emergence of\natomically thin two-dimensional (2D) materials has opened up possibilities for\nthe design of ultra-thin and flexible nanoelectronic devices. As truly 2D\nmaterials, they exhibit an optimal surface-to-volume ratio, which results in an\nextremely high sensitivity to external changes. This makes these materials\noptimal candidates for sensing applications. Here, we exploit the remarkably\ndiverse exciton landscape in monolayer transition metal dichalcogenides to\npropose a novel dark-exciton-based concept for ultra sensitive strain sensors.\nWe demonstrate that the dark-bright-exciton separation can be controlled by\nstrain, which has a crucial impact on the activation of dark excitonic states.\nThis results in a pronounced intensity change of dark excitons in\nphotoluminescence spectra, when only 0.05 $\\%$ strain is applied. The predicted\nextremely high optical gauge factors of up to 8000 are promising for the design\nof optical strain sensors."
    },
    {
        "anchor": "Symmetry breaking in spin spirals and skyrmions by in-plane and canted\n  magnetic fields: The influence of in-plane and canted magnetic fields on spin spirals and\nskyrmions in atomic bilayer islands of palladium and iron on an Ir(111)\nsubstrate is investigated by scanning tunnelling microscopy at low\ntemperatures. It is shown that the spin spiral propagation direction is\ndetermined by the island's border which can be explained by equilibrium state\ncalculations on a triangular lattice. By application of in-plane fields, the\nspin spiral reorientates its propagation direction and becomes distorted,\nthereby allowing a proof for its cycloidal nature. Furthermore, it is\ndemonstrated that the skyrmions' shape is distorted in canted fields which\nallows to determine the sense of magnetisation rotation as enforced by the\ninterfacial Dzyaloshinskii-Moriya interaction.",
        "positive": "Spin-Dependent Conductance in a Junction with Dresselhaus Spin-Orbit\n  Coupling: We studied spin-dependent conductance in a normal metal (NM)/NM junction with\nDresselhaus spin-orbit coupling (DSOC) and magnetization. As a reference, we\nalso studied the spin-dependent conductance in such a junction with Rashba\nspin-orbit coupling (RSOC). Using a standard scattering method, we calculated\nthe gate-voltage dependence of the spin-dependent conductances in DSOC and\nRSOC. In addition, we calculated the gate-voltage dependence of the\nconductances in a ferromagnetic metal (FM)/NM junction with spin-orbit coupling\nand magnetization, which we call ferromagnetic spin-orbit metal (FSOM). From\nthese results, we discuss the relation between these conductance in the\npresence of DSOC and that in the presence of RSOC. We found that conductance in\nDSOC is the same as that in RSOC for the NM/FSOM junction. In addition, we\nfound that in the FM/FSOM junction, the conductance in DSOC is the same as that\nin RSOC only when the FM magnetization is along the out-of-plane direction."
    },
    {
        "anchor": "Measurement of the energy dependence of phase relaxation by single\n  electron tunneling: Single electron tunneling through a single impurity level is used to probe\nthe fluctuations of the local density of states in the emitter. The energy\ndependence of quasi-particle relaxation in the emitter can be extracted from\nthe damping of the fluctuations of the local density of states (LDOS). At\nlarger magnetic fields Zeeman splitting is observed.",
        "positive": "Non linear transport theory for negative-differential resistance states\n  of two dimensional electron systems in strong magnetic fields: We present a model to describe the nonlinear response to a direct dc current\napplied to a two-dimensional electron system in a strong magnetic field. The\nmodel is based on the solution of the von Neumann equation incorporating the\nexact dynamics of two-dimensional damped electrons in the presence of\narbitrarily strong magnetic and dc electric fields, while the effects of\nrandomly distributed impurities are perturbatively added. From the analysis of\nthe differential resistivity and the longitudinal voltage we observe the\nformation of negative differential resistivity states (NDRS) that are the\nprecursors of the zero differential resistivity states (ZDRS). The theoretical\npredictions correctly reproduce the main experimental features provided that\nthe inelastic scattering rate obey a $T^2$ temperature dependence, consistent\nwith electron-electron interaction effects."
    },
    {
        "anchor": "Enhancement of tunneling density of states at a Y junction of spin-1/2\n  Tomonaga Luttinger liquid wires: We calculate the tunneling density of states (TDOS) in a three wire junction\nof interacting spin-1/2 electrons, and find an anomalous enhancement of the\nTDOS in the zero bias limit, even for repulsive interactions for several\nbosonic fixed points. This enhancement is physically related to the reflection\nof holes from the junction for incident electrons, and it occurs only in the\nvicinity of the junction ($x < v_{\\rm min}/2\\omega$ where $v_{\\rm min}$ is the\nminimum of the velocity of charge or spin excitations and $\\omega$ is the bias\nfrequency), crossing over to the bulk value which is always suppressed, at\nlarger distances. The TDOS exponent can be directly probed in a STM experiment\nby measuring the differential tunneling conductance as a function of either the\nbias voltage or temperature as done in C. Blumenstein et al. Nature Physics 7,\n776 (2011).",
        "positive": "Nonequilibrium Fluctuations and Decoherence in Nanomechanical Devices\n  Coupled to the Tunnel Junction: We analyze the dynamics of a nanomechanical oscillator coupled to an\nelectrical tunnel junction with an arbitrary voltage applied to the junction\nand arbitrary temperature of electrons in leads. We obtain the explicit\nexpressions for the fluctuations of oscillator position, its\ndamping/decoherence rate, and the current through the structure. It is shown\nthat quantum heating of the oscillator results in nonlinearity of the\ncurrent-voltage characteristics. The effects of mechanical vacuum fluctuations\nare also discussed."
    },
    {
        "anchor": "Superlattice design for optimal thermoelectric generator performance: We consider the design of an optimal superlattice thermoelectric generator\nvia the energy bandpass filter approach. Various configurations of superlattice\nstructures are explored to obtain a bandpass transmission spectrum that\napproaches the ideal ``boxcar'' form, which is now well known to manifest the\nlargest efficiency at a given output power. Using the non-equilibrium Green's\nfunction formalism coupled self-consistently with the Poisson's equation, we\nidentify such an ideal structure and also demonstrate that it is almost immune\nto the deleterious effect of self-consistent charging and device variability.\nAnalyzing various superlattice designs, we conclude that superlattices with a\nGaussian distribution of the barrier thickness offers the best thermoelectric\nefficiency at maximum power. It is observed that the best operating regime of\nthis device design provides a maximum power in the range of 0.32-0.46 $MW/m^2$\nat efficiencies between 54\\%-43\\% of Carnot efficiency. We also analyze our\ndevice designs with the conventional figure of merit approach to counter\nsupport the results so obtained. We note a high $zT_{el}=6$ value in the case\nof Gaussian distribution of the barrier thickness. With the existing advanced\nthin-film growth technology, the suggested superlattice structures can be\nachieved, and such optimized thermoelectric performances can be realized.",
        "positive": "Time-crystalline long-range order in chiral fermionic vacuum: It is widely believed that there is no macroscopic time-crystalline order in\nthe ground states of short-range interacting systems. In this paper, we\nconsider a time-dependent correlation function for an order operator with a\nspatially discontinuous weight in a one-dimensional chiral fermionic system.\nAlthough both the Hamiltonian and the order parameter are composed of spatially\nlocal operators, the time-dependent correlation function diverges\nlogarithmically in equal time intervals. This result implies a breakdown of an\ninequality that claims the absence of time-crystalline long-range order in the\nground states, unless the upper-bound constant is set to be infinity. This\nbehavior is due to the combination of the discontinuity of the order operator\nand the infinite dimensionality of quantum field theory. In the language of\nbosonization, it can also be related to the divergence of a space-time-resolved\nbosonic correlation function."
    },
    {
        "anchor": "Pumping of vibrational excitations in a Coulomb blockaded suspended\n  carbon nanotube: Low-temperature transport spectroscopy measurements on a suspended few-hole\ncarbon nanotube quantum dot are presented, showing a gate-dependent harmonic\nexcitation spectrum which, strikingly, occurs in the Coulomb blockade regime.\nThe quantized excitation energy corresponds to the scale expected for\nlongitudinal vibrations of the nanotube. The electronic transport processes are\nidentified as cotunnel-assisted sequential tunneling, resulting from\nnon-equilibrium occupation of the mechanical mode. They appear only above a\nhigh-bias threshold at the scale of electronic nanotube excitations. We discuss\nmodels for the pumping process that explain the enhancement of the\nnon-equilibrium occupation and show that it is connected to a subtle interplay\nbetween electronic and vibrational degrees of freedom.",
        "positive": "Fractional Quantum Hall Physics in Jaynes-Cummings-Hubbard Lattices: Jaynes-Cummings-Hubbard arrays provide unique opportunities for quantum\nemulation as they exhibit convenient state preparation and measurement, and\nin-situ tuning of parameters. We show how to realise strongly correlated states\nof light in Jaynes-Cummings-Hubbard arrays under the introduction of an\neffective magnetic field. The effective field is realised by dynamic tuning of\nthe cavity resonances. We demonstrate the existence of Fractional Quantum Hall\nstates by com- puting topological invariants, phase transitions between\ntopologically distinct states, and Laughlin wavefunction overlap."
    },
    {
        "anchor": "Spin-orbital effect on polariton state in traps: I discuss similitude and differences of spin-orbital effects for electrons in\nquantum wells with the Rashba coupling and for polaritons in semiconductor\nmicrocavities with TE-TM splitting. Contrary to the case of electron, the\nground state of polariton in the trap can be non-degenerate and can possess\nspecific polarization structure. For the case of azimuthally symmetric trap and\nsufficiently strong spin-orbital coupling, the ground state is either radial or\nazimuthal vortex, depending on the sign of the coupling constant. The effect is\nstrongly enhanced for polaritons trapped in a ring, where even weak TE-TM\nsplitting results in formation of vorticity and definite polarization of the\nground state. The Hamiltonian for quasi-1D motion of polaritons in the ring is\nderived and it is shown the the dispersion of polaritons depend qualitatively\non the curvature of the ring.",
        "positive": "Fokker-Planck approach to the theory of magnon-driven spin Seebeck\n  effect: Following the theoretical approach by Xiao et al [Phys. Rev. B 81, 214418\n(2010)] to the spin Seebeck effect, we calculate the mean value of the total\nspin current flowing through a normalmetal/ ferromagnet interface. The spin\ncurrent emitted from the ferromagnet to the normal metal is evaluated in the\nframework of the Fokker-Planck approach for the stochastic\nLandau-Lifshitz-Gilbert equation. We show that the total spin current depends\nnot only on the temperature difference between the electron and the magnon\nbaths, but also on the external magnetic field and magnetic anisotropy. Apart\nfrom this, the spin current is shown to saturate with increasing magnon\ntemperature, and the saturation temperature increases with increasing magnetic\nfield and/or magnetic anisotropy."
    },
    {
        "anchor": "Charge induced coherence between intersubband plasmons in a quantum\n  structure: In this work we investigate a low dimensional semiconductor system, in which\nthe light-matter interaction is enhanced by the cooperative behavior of a large\nnumber of dipolar oscillators, at different frequencies, mutually phase locked\nby Coulomb interaction. We experimentally and theoretically demonstrate that,\nowing to this phenomenon, the optical response of a semiconductor quantum well\nwith several occupied subbands is a single sharp resonance, associated to the\nexcitation of a bright multisubband plasmon. This effect illustrates how the\nwhole oscillator strength of a two-dimensional system can be concentrated into\na single resonance independently from the shape of the confining potential.\nWhen this cooperative excitation is tuned in resonance with a cavity mode,\ntheir coupling strength can be increased monotonically with the electronic\ndensity, allowing the achievement of the ultra-strong coupling regime up to\nroom temperature.",
        "positive": "Ultra-low carrier concentration and surface dominant transport in\n  Sb-doped Bi2Se3 topological insulator nanoribbons: A topological insulator is a new state of matter, possessing gapless\nspin-locking surface states across the bulk band gap which has created new\nopportunities from novel electronics to energy conversion. However, the large\nconcentration of bulk residual carriers has been a major challenge for\nrevealing the property of the topological surface state via electron transport\nmeasurement. Here we report surface state dominated transport in Sb-doped\nBi2Se3 nanoribbons with very low bulk electron concentrations. In the\nnanoribbons with sub-10nm thickness protected by a ZnO layer, we demonstrate\ncomplete control of their top and bottom surfaces near the Dirac point,\nachieving the lowest carrier concentration of 2x10^11/cm2 reported in\nthree-dimensional (3D) topological insulators. The Sb-doped Bi2Se3\nnanostructures provide an attractive materials platform to study fundamental\nphysics in topological insulators, as well as future applications."
    },
    {
        "anchor": "External gates and transport in biased bilayer graphene: We formulate a theory of transport in graphene bilayers in the weak momentum\nscattering regime in such a way as to take into account contributions to the\nelectrical conductivity to leading and next-to-leading order in the scattering\npotential. The response of bilayers to an electric field cannot be regarded as\na sum of terms due to individual layers. Rather, interlayer tunneling and\ncoherence between positive- and negative-energy states give the main\ncontributions to the conductivity. At low energies, the dominant effect of\nscattering on transport comes from scattering within each energy band, yet a\nsimple picture encapsulating the role of collisions in a set of scattering\ntimes is not applicable. Coherence between positive- and negative-energy states\ngives, as in monolayers, a term in the conductivity which depends on the order\nof limits. The application of an external gate, which introduces a gap between\npositive- and negative-energy states, does not affect transport. Nevertheless\nthe solution to the kinetic equation in the presence of such a gate is very\nrevealing for transport in both bilayers and monolayers.",
        "positive": "Auxiliary Calculations for Graphene-Based Quantum Hall Arrays Using\n  Partially Recursive Star-Mesh Transformations: A previous mathematical approach adopted for optimizing the number of total\ndevice elements required for obtaining high effective quantized resistances in\ngraphene-based quantum Hall array devices (QHARS) has been further explored\nwith partial recursion patterns. Designs would assume the use of epitaxial\ngraphene elements, whose quantized Hall resistance at the {\\nu}=2 plateau (R_H\n\\approx 12906.4 \\Ohm) becomes the building block for larger effective,\nquantized resistances. Auxiliary calculations suggest the importance of\napplying full recursions at least once to maximize the reduction of total QHARS\nelements needed for high resistances."
    },
    {
        "anchor": "NMR profiling of quantum electron solids in high magnetic fields: When the motion of electrons is restricted to a plane under a perpendicular\nmagnetic field B, a variety of quantum phases emerge at low temperatures whose\nproperties are dictated by the Coulomb interaction and its interplay with\ndisorder. At very strong B, the sequence of fractional quantum Hall (FQH)\nliquid phases terminates in an insulating phase, which is widely believed to be\ndue to the solidification of electrons into domains possessing Wigner crystal\n(WC) order. The existence of such WC domains is signaled by the emergence of\nmicrowave pinning-mode resonances, which reflect the mechanical properties\ncharacteristic of a solid. However, the most direct manifestation of the broken\ntranslational symmetry accompanying the solidification - the spatial modulation\nof particles' probability amplitude - has not been observed yet. Here, we\ndemonstrate that nuclear magnetic resonance (NMR) provides a direct probe of\nthe density topography of electron solids in the integer and fractional quantum\nHall regimes. The data uncover quantum and thermal fluctuation of lattice\nelectrons resolved on the nanometre scale. Our results pave the way to studies\nof other exotic phases with non-trivial spatial spin/charge order.",
        "positive": "Current-induced motion of a transverse magnetic domain wall in the\n  presence of spin Hall effect: We theoretically study the current-induced dynamics of a transverse magnetic\ndomain wall in bi-layer nanowires consisting of a ferromagnet on top of a\nnonmagnet having strong spin-orbit coupling. Domain wall dynamics is\ncharacterized by two threshold current densities, $J_{th}^{WB}$ and\n$J_{th}^{REV}$, where $J_{th}^{WB}$ is a threshold for the chirality switching\nof the domain wall and $J_{th}^{REV}$ is another threshold for the reversed\ndomain wall motion caused by spin Hall effect. Domain walls with a certain\nchirality may move opposite to the electron-flow direction with high speed in\nthe current range $J_{th}^{REV} < J < J_{th}^{WB}$ for the system designed to\nsatisfy the conditions $J_{th}^{WB} > J_{th}^{REV}$ and \\alpha > \\beta, where\n\\alpha is the Gilbert damping constant and \\beta is the nonadiabaticity of spin\ntorque. Micromagnetic simulations confirm the validity of analytical results."
    },
    {
        "anchor": "Built-in electric field and strain tunable valley-related multiple\n  topological phase transitions in VSiXN$_4$ (X= C, Si, Ge, Sn, Pb) monolayers: The valley-related multiple topological phase transitions attracted\nsignificant attention due to their providing significant opportunities for\nfundamental research and practical applications. However, unfortunately, to\ndate there is no real material that can realize valley-related multiple\ntopological phase transitions. Here, through first-principles calculations and\nmodel analysis, we investigate the structural, magnetic, electronic, and\ntopological properties of VSiXN$_4$ (X = C, Si, Ge, Sn, Pb) monolayers.\nVSiXN$_4$ monolayers are stable and intrinsically ferrovalley materials.\nIntriguingly, we found that the built-in electric field and strain can induce\nvalley-related multiple topological phase transitions in the materials from\nvalley semiconductor to valley-half-semimetal, to valley quantum anomalous Hall\ninsulator, to valley-half-semimetal, and to valley semiconductor (or to\nvalley-metal). The nature of topological phase transition is the built-in\nelectric field and strain induce band inversion between the\nd$_{xy}$/d$_{x2-y2}$ and d$_{z2}$ at obritals at K and K' valleys. Our findings\nnot only reveal the mechanism of multiple topological phase transitions, but\nalso provides an ideal platform for the multi-field manipulating the spin,\nvalley, and topological physics. It will open new perspectives for spintronic,\nvalleytronic, and topological nanoelectronic applications based on these\nmaterials.",
        "positive": "Photon mediated interaction between distant quantum dot circuits: Engineering the interaction between light and matter is an important goal in\nthe emerging field of quantum opto-electronics. Thanks to the use of cavity\nquantum electrodynamics architectures, one can envision a fully hybrid\nmultiplexing of quantum conductors. Here, we use such an architecture to couple\ntwo quantum dot circuits . Our quantum dots are separated by 200 times their\nown size, with no direct tunnel and electrostatic couplings between them. We\ndemonstrate their interaction, mediated by the cavity photons. This could be\nused to scale up quantum bit architectures based on quantum dot circuits or\nsimulate on-chip phonon-mediated interactions between strongly correlated\nelectrons."
    },
    {
        "anchor": "Spin-Flip Transistor: The recently developed semiclassical theory for magnetoelectronic circuits is\napplied to a transistor-like device consisting of a normal metal island and\nthree magnetic terminals. The electric current between source and drain can be\ncontrolled by the magnetization of a ``base'' reservoir up to distances of the\norder of the spin-flip diffusion length.",
        "positive": "Writing Spin in a Quantum Dot with Ferromagnetic and Superconducting\n  Electrodes: We propose an efficient mechanism for the operation of writing spin in a\nquantum dot, which is an ideal candidate for qubit. The idea is based on the\nAndreev reflection induced spin polarization (ARISP) in a ferromagnetic /\nquantum-dot / superconductor system. We find that on the resonance of Andreev\nreflection, the spin polarization of quantum dot strongly denpends on the\nmagnetization of ferromagnetic electrode, and the sign of the spin polarization\nis controllable by bias voltage. In the presence of intradot Coulomb\ninteraction, we show that ARISP effect can still survive as long as the\ncharging energy is comparable to the superconducting gap. Detailed conditions\nand properties of ARISP are also discussed."
    },
    {
        "anchor": "Influence of interactions on the anomalous quantum Hall effect: The anomalous quantum Hall conductivity in the 2+1D topological insulators in\nthe absence of interactions may be expressed as the topological invariant\ncomposed of the two - point Green function. For the noninteracting system this\nexpression is the alternative way to represent the TKNN invariant. It is widely\nbelieved that in the presence of interactions the Hall conductivity is given by\nthe same expression, in which the noninteracting two - point Green function is\nsubstituted by the complete two - point Green function with the interactions\ntaken into account. However, the proof of this statement has not been given so\nfar. In the present paper we give such a proof in the framework of the\nparticular tight - binding models of the $2+1$ D topological insulator.\nBesides, we extend our consideration to the $3+1$ D Weyl semimetals. It was\nknown previously that with the interactions neglected the Hall conductivity in\nthose systems is expressed through the two - point Green function in the way\nsimilar to that of the $2+1$ D topological insulators. Again, the influence of\ninteractions on this expression has not been investigated previously. We\nconsider this problem within the framework of the particular $3+1$D model of\nWeyl semimetal in the presence of the contact four - fermion interactions and\nCoulomb interactions. We prove (up to the one - loop approximation), that the\nHall conductivity is given by the same expression as in the noninteracting\ncase, in which the noninteracting Green function is substituted by the complete\ntwo - point Green function with the interactions included. Basing on the\nobtained expressions we discuss the topological phase transitions accompanied\nby the change of Hall conductivity.",
        "positive": "Single photon emission and detection at the nanoscale utilizing\n  semiconductor nanowires: We report recent progress toward on-chip single photon emission and detection\nin the near infrared utilizing semiconductor nanowires. Our single photon\nemitter is based on a single InAsP quantum dot embedded in a p-n junction\ndefined along the growth axis of an InP nanowire. Under forward bias, light is\nemitted from the single quantum dot by electrical injection of electrons and\nholes. The optical quality of the quantum dot emission is shown to improve when\nsurrounding the dot material by a small intrinsic section of InP. Finally, we\nreport large multiplication factors in excess of 1000 from a single Si nanowire\navalanche photodiode comprised of p-doped, intrinsic, and n-doped sections. The\nlarge multiplication factor obtained from a single Si nanowire opens up the\npossibility to detect a single photon at the nanoscale."
    },
    {
        "anchor": "Enhancement of acoustic spin pumping by acoustic distributed Bragg\n  reflector cavity: Surface acoustic waves (SAWs) in the GHz frequency range can inject spin\ncurrents dynamically into adjacent nonmagnetic layers via spin pumping effect\nassociated with ferromagnetic resonance. Here, we demonstrate an enhancement of\nacoustic ferromagnetic resonance and spin current generation by a pair of SAW\nreflector gratings, which form an acoustic analogue of the distributed Bragg\nreflector cavity. In the experiment, we confirmed 2.04 $\\pm$ 0.02 times larger\nSAW power absorption in a device with cavity than in case of no acoustic\ncavity. We confirmed up to 2.96 $\\pm$ 0.02 times larger spin current generation\nby measuring electric voltages generated by the inverse Edelstein effect (IEE)\nat the interface between Cu and Bi$_2$O$_3$. The results suggest that acoustic\ncavities would be useful to enhance the conversion efficiency in SAW driven\ncoupled magnon-phonon dynamics.",
        "positive": "Stable Switching among High-Order Modes in Polariton Condensates: We report multistate optical switching among high-order bouncing-ball modes\n(\"ripples\") and whispering-gallerying modes (\"petals\") of exciton-polariton\ncondensates in a laser-generated annular trap. By tailoring the diameter and\npower of the annular trap, the polariton condensate can be switched among\ndifferent trapped modes, accompanied by redistribution of spatial densities and\nsuperlinear increase in the emission intensities, implying that polariton\ncondensates in this geometry could be exploited for a multistate switch. A\nmodel based on non-Hermitian modes of the generalized Gross-Pitaevskii equation\nreveals that this mode switching arises from competition between pump-induced\ngain and in-plane polariton loss. The parameters for reproducible switching\namong trapped modes have been measured experimentally, giving us a phase\ndiagram for mode switching. Taken together, the experimental result and\ntheoretical modeling advances our fundamental understanding of the spontaneous\nemergence of coherence and move us toward its practical exploitation."
    },
    {
        "anchor": "Spatial Distribution of the Incompressible Strips at Aharonov-Bohm\n  Interferometer: In this work, the edge physics of an Aharonov-Bohm interferometer (ABI)\ndefined on a two dimensional electron gas, subject to strong perpendicular\nmagnetic field B, is investigated. We solve the three dimensional Poisson\nequation using numerical techniques starting from the crystal growth parameters\nand surface image of the sample. The potential profiles of etched and gate\ndefined geometries are compared and it is found that the etching yields a\nsteeper landscape. The spatial distribution of the incompressible strips is\ninvestigated as a function of the gate voltage and applied magnetic field,\nwhere the imposed current is confined to. AB interference is investigated due\nto scattering processes between two incompressible \"edge-states\".",
        "positive": "Spin-current induced mechanical torque in a chiral molecular junction: We analyse the appearance of a mechanical torque that acts on a chiral\nmolecule: a single-stranded DNA, in which the spin-orbit interaction is\nexpected to induce a spin-selectivity effect. The mechanical torque is shown to\nappear as a result of the non-conservation of the spin current in the presence\nof the spin-orbit interaction. Adopting a simple microscopic model Hamiltonian\nfor a chiral molecule connected to source and drain leads, and accounting for\nthe mechanical torque acting on the chiral molecule as the back action on the\nelectrons traversing the molecule, we derive the spin continuity-equation. It\nconnects the spin current expressed by a Landauer-type formula and the\nmechanical torque. Thus, by injecting a spin-polarized current from the source\nelectrode, it is possible to generate a torque, which will rotate the DNA\nmolecule."
    },
    {
        "anchor": "Topological valleytronics: Brought to light: The topological valley Hall effect was predicted as a consequence of the bulk\ntopology of electronic systems. Now it has been observed in photonic crystals,\nshowing that both topology and valley are innate to classical as well as\nquantum systems.\n  The discovery of counterflow in opposite valleys not only demonstrates that\nthe valley can be a novel carrier of information and energy --- particularly\nvaluable for systems without charge and spin --- but also exemplifies that\nsymmetry-protected band topology can be universal to both quantum and classical\nsystems.",
        "positive": "Half-metal and other fractional metal phases in doped AB bilayer\n  graphene: We theoretically argue that, in doped AB bilayer graphene, the\nelectron-electron coupling can give rise to the spontaneous formation of\nfractional metal phases. These states, being generalizations of a more common\nhalf-metal, have a Fermi surface that is perfectly polarized not only in terms\nof a spin-related quantum number, but also in terms of the valley index. The\nproposed mechanism assumes that the ground state of undoped bilayer graphene is\na spin density wave insulator, with a finite gap in the single-electron\nspectrum. Upon doping, the insulator is destroyed, and replaced by a fractional\nmetal phase. As doping increases, transitions between various types of\nfractional metal (half-metal, quarter-metal, etc.) are triggered. Our findings\nare consistent with recent experiments on doped AB bilayer graphene, in which a\ncascade of phase transitions between different isospin states was observed."
    },
    {
        "anchor": "Optically Controlled Excitonic Transistor: Optical control of exciton fluxes is realized for indirect excitons in a\ncrossed-ramp excitonic device. The device demonstrates experimental proof of\nprinciple for all-optical excitonic transistors with a high ratio between the\nexcitonic signal at the optical drain and the excitonic signal due to the\noptical gate. The device also demonstrates experimental proof of principle for\nall-optical excitonic routers.",
        "positive": "Electric-field-induced coherent coupling of the exciton states in a\n  single quantum dot: The signature of coherent coupling between two quantum states is an\nanticrossing in their energies as one is swept through the other. In single\nsemiconductor quantum dots containing an electron-hole pair the eigenstates\nform a two-level system that can be used to demonstrate quantum effects in the\nsolid state, but in all previous work these states were independent. Here we\ndescribe a technique to control the energetic splitting of these states using a\nvertical electric field, facilitating the observation of coherent coupling\nbetween them. Near the minimum splitting the eigenstates rotate in the plane of\nthe sample, being orientated at 45{\\deg} when the splitting is smallest. Using\nthis system we show direct control over the exciton states in one quantum dot,\nleading to the generation of entangled photon pairs."
    },
    {
        "anchor": "Canonical Schottky barrier heights of the transition metal\n  dichalcogenide monolayers in contact with a metal: The transition metal dichalcogenide ($MX_{2}$, where $M$=Mo, W and $X$=S, Se,\nTe) monolayers are of high interest for semiconducting applications at the\nnanoscale level; this interest is due to both their direct band gaps and high\ncharge mobilities. In this regard, an in-depth understating of the related\nSchottky barrier heights, associated with the incorporation of $MX_{2}$ sheets\ninto novel low-dimensional metal-semiconductor junctions, is of crucial\nimportance. Herein, we generate and provide analysis of the Schottky barrier\nheights behavior to account for the metal-induced gap states concept as its\nexplanation. In particular, the present investigations concentrate on the\nestimation of the charge neutrality levels directly by employing the primary\ntheoretical model, $i.e.$ the cell-averaged Green's function formalism combined\nthe complex band structure technique. The results presented herein place charge\nneutrality levels in the vicinity of the mid-gap; this is in agreement with\nprevious reports and analogous to the behavior of three-dimensional\nsemiconductors. The calculated canonical Schottky barrier heights are also\nfound to be in agreement with other computational and experimental values in\ncases where the difference between electronegativities of the semiconductor and\nmetal contact is small. Moreover, the influence of the spin-orbit effects is\nherein considered and supports that Schottky barrier heights have metal-induced\ngap state-derived character, regardless whether spin-orbit coupling\ninteractions are considered. The results presented within this report\nconstitute a direct and vital verification of the importance of metal-induced\ngap states in explaining the behavior of observed Schottky barrier heights at\n$MX_{2}$-metal junctions.",
        "positive": "Statistical properties of spontaneous emission near a rough surface: We study the lifetime of the excited state of an atom or molecule near a\nplane surface with a given random surface roughness. In particular, we discuss\nthe impact of the scattering of surface modes within the rough surface. Our\nstudy is completed by considering the lateral correlation length of the decay\nrate and the variance discussing its relation to the C0 correlation."
    },
    {
        "anchor": "Anisotropic Quantum Hall Droplets: We study two-dimensional (2D) droplets of noninteracting electrons in a\nstrong magnetic field, placed in a confining potential with arbitrary shape.\nUsing semiclassical methods adapted to the lowest Landau level, we obtain\nnear-Gaussian energy eigenstates that are localized on level curves of the\npotential and have a position-dependent height. This one-particle insight\nallows us to deduce explicit formulas for expectation values of local many-body\nobservables, such as density and current, in the thermodynamic limit. In\nparticular, correlations along the edge are long-ranged and inhomogeneous. As\nwe show, this is consistent with the system's universal low-energy description\nas a free 1D chiral conformal field theory of edge modes, known from earlier\nworks in simple geometries. A delicate interplay between radial and angular\ndependencies of eigenfunctions ultimately ensures that the theory is\nhomogeneous in terms of the canonical angle variable of the potential, despite\nits apparent inhomogeneity in terms of more na\\\"ive angular coordinates.\nFinally, we propose a scheme to measure the anisotropy by subjecting the\ndroplet to microwave radiation; we compute the corresponding absorption rate\nand show that it depends on the droplet's shape and the waves' polarization.\nThese results, both local and global, are likely to be observable in\nsolid-state systems or quantum simulators of 2D electron gases with a high\ndegree of control on the confining potential.",
        "positive": "Resonant photon absorption in the low spin molecule V15: We report the first study of the micro-SQUID response of a molecular system\nto electromagnetic radiation. The advantages of our micro-SQUID technique in\nrespect to pulsed electron paramagnetic resonance (EPR) techniques consist in\nthe possibility to perform time-resolved experiments (below 1 ns) on\nsubmicrometer sizes samples (about 1000 spins) at low temperature (below 100\nmK).\n  Resonant photon absorption in the GHz range was observed via low temperature\nmicro-SQUID magnetization measurements of the spin ground state S = 1/2 of the\nmolecular complex V15. The line-width essentially results from intra-molecular\nhyperfine interaction. The results point out that observing Rabi oscillations\nin molecular nanomagnets requires well isolated low spin systems and high\nradiation power. Our first results open the way for time-resolved observations\nof quantum superposition of spin-up and spin-down states in SMMs."
    },
    {
        "anchor": "Microscopics of disordered two-dimensional electron gases under high\n  magnetic fields: Equilibrium properties and dissipation in the hydrodynamic\n  regime: We develop in detail a new formalism [as a sequel to the work of T. Champel\nand S. Florens, Phys. Rev. B 75, 245326 (2007)] that is well-suited for\ntreating quantum problems involving slowly-varying potentials at high magnetic\nfields in two-dimensional electron gases. For an arbitrary smooth potential we\nshow that electronic Green's function is fully determined by closed recursive\nexpressions that take the form of a high magnetic field expansion in powers of\nthe magnetic length l_B. For illustration we determine entirely Green's\nfunction at order l_B^3, which is then used to obtain quantum expressions for\nthe local charge and current electronic densities at equilibrium. Such results\nare valid at high but finite magnetic fields and for arbitrary temperatures, as\nthey take into account Landau level mixing processes and wave function\nbroadening. We also check the accuracy of our general functionals against the\nexact solution of a one-dimensional parabolic confining potential,\ndemonstrating the controlled character of the theory to get equilibrium\nproperties. Finally, we show that transport in high magnetic fields can be\ndescribed hydrodynamically by a local equilibrium regime and that dissipation\nmechanisms and quantum tunneling processes are intrinsically included at the\nmicroscopic level in our high magnetic field theory. We calculate microscopic\nexpressions for the local conductivity tensor, which possesses both transverse\nand longitudinal components, providing a microscopic basis for the\nunderstanding of dissipative features in quantum Hall systems.",
        "positive": "Macroscopic Resonant Tunneling in the Presence of Low Frequency Noise: We develop a theory of macroscopic resonant tunneling of flux in a\ndouble-well potential in the presence of realistic flux noise with significant\nlow-frequency component. The rate of incoherent flux tunneling between the\nwells exhibits resonant peaks, the shape and position of which reflect\nqualitative features of the noise, and can thus serve as a diagnostic tool for\nstudying the low-frequency flux noise in SQUID qubits. We show, in particular,\nthat the noise-induced renormalization of the first resonant peak provides\ndirect information on the temperature of the noise source and the strength of\nits quantum component."
    },
    {
        "anchor": "Ballistic transport in disordered graphene: An analytic theory of electron transport in disordered graphene in a\nballistic geometry is developed. We consider a sample of a large width W and\nanalyze the evolution of the conductance, the shot noise, and the full\nstatistics of the charge transfer with increasing length L, both at the Dirac\npoint and at a finite gate voltage. The transfer matrix approach combined with\nthe disorder perturbation theory and the renormalization group is used. We also\ndiscuss the crossover to the diffusive regime and construct a ``phase diagram''\nof various transport regimes in graphene.",
        "positive": "Generation and Hall effect of skyrmions enabled via using nonmagnetic\n  point contacts: To enable functional skyrmion based spintronic devices, the controllable\ngeneration and manipulation of skyrmions is essential. While the generation of\nskyrmions by using a magnetic geometrical constriction has already been\ndemonstrated, this approach is difficult to combine with a subsequent\ncontrolled manipulation of skyrmions. The high efficiency of skyrmion\ngeneration from magnetic constrictions limits the useful current density,\nresulting in stochastic skyrmion motion, which may obscure topological\nphenomena such as the skyrmion Hall effect. In order to address this issue, we\ndesigned a nonmagnetic conducting Ti/Au point contact in devices made of\nTa/CoFeB/TaOx trilayer films. By applying high voltage pulses, we\nexperimentally demonstrated that skyrmions can be dynamically generated.\nMoreover, the accompanied spin topology dependent skyrmion dynamics, the\nskyrmion Hall effect is also experimentally observed in the same devices. The\ncreation process has been numerically reproduced through micromagnetic\nsimulations in which the important role of skyrmion-antiskyrmion pair\ngeneration is identified. The motion and Hall effect of the skyrmions,\nimmediately after their creation is described using a modified Thiele equation\nafter taking into account the contribution from spatially inhomogeneous\nspin-orbit torques and the Magnus force. The simultaneous generation and\nmanipulation of skyrmions using a nonmagnetic point contact could provide a\nuseful pathway for designing novel skyrmion based devices."
    },
    {
        "anchor": "Entropy Driven Inductive Response of Topological Insulators: 3D topological insulators are characterized by an insulating bulk and\nextended surface states exhibiting a helical spin texture. In this work, we\ninvestigate the hyperfine interaction between the spin-charge coupled transport\nof electrons and the nuclear spins in these surface states. Previous work has\npredicted that in the quantum spin Hall insulator phase, work can be extracted\nfrom a bath of polarized nuclear spins as a resource. We employ nonequilibrium\nGreen's function analysis to show that a similar effect exists on the surface\nof a 3D topological insulator, albeit rescaled by the ratio between electronic\nmean free path and device length. The induced current due to thermal relaxation\nof polarized nuclear spins has an inductive nature. We emphasize the inductive\nresponse by rewriting the current-voltage relation in harmonic response as a\nlumped element model containing two parallel resistors and an inductor. In a\nlow-frequency analysis, a universal inductance value emerges that is only\ndependent on the device's aspect ratio. This scaling offers a means of\nminiaturizing inductive circuit elements. An efficiency estimate follows from\ncomparing the spin-flip induced current to the Ohmic contribution. The\ninductive effect is most prominent in topological insulators which have a large\nnumber of spinful nuclei per coherent segment, of which the volume is given by\nthe mean free path length, Fermi wavelength and penetration depth of the\nsurface state.",
        "positive": "Giant Casimir torque between rotated gratings and the $\u03b8=0$ anomaly: We study the Casimir torque between two metallic one-dimensional gratings\nrotated by an angle $\\theta$ with respect to each other. We find that, for\ninfinitely extended gratings, the Casimir energy is anomalously discontinuous\nat $\\theta=0$, due to a critical zero-order geometric transition between a 2D-\nand a 1D-periodic system. This transition is a peculiarity of the grating\ngeometry and does not exist for intrinsically anisotropic materials. As a\nremarkable practical consequence, for finite-size gratings, the torque per area\ncan reach extremely large values, increasing without bounds with the size of\nthe system. We show that for finite gratings with only 10 period repetitions,\nthe maximum torque is already 60 times larger than the one predicted in the\ncase of infinite gratings. These findings pave the way to the design of a\ncontactless quantum vacuum torsional spring, with possible relevance to micro-\nand nano-mechanical devices."
    },
    {
        "anchor": "Polar optical phonons in wurtzite spheroidal quantum dots: Theory and\n  application to ZnO and ZnO/MgZnO nanostructures: Polar optical-phonon modes are derived analytically for spheroidal quantum\ndots with wurtzite crystal structure. The developed theory is applied to a\nfreestanding spheroidal ZnO quantum dot and to a spheroidal ZnO quantum dot\nembedded into a MgZnO crystal. The wurtzite (anisotropic) quantum dots are\nshown to have strongly different polar optical-phonon modes in comparison with\nzincblende (isotropic) quantum dots. The obtained results allow one to explain\nand accurately predict phonon peaks in the Raman spectra of wurtzite\nnanocrystals, nanorods (prolate spheroids), and epitaxial quantum dots (oblate\nspheroids).",
        "positive": "Modification of Landau levels in a two-dimensional ring due to rotation\n  effects and edge states: We investigate the properties of a two-dimensional quantum ring under\nrotating and external magnetic field effects. We initially analyse the Landau\nlevels and inertial effects on them. Among the results obtained, we emphasize\nthat the rotation lifted the degeneracy of Landau levels. When electrons are\nconfined in a two-dimensional ring, which is modeled by a hard wall potential,\nthe eigenstates are described by Landau states as long as the eigenstates are\nnot too close to the edges of the ring. On the other hand, near the edges of\nthe ring, the energies increase monotonically. These states are known as edge\nstates. Edge states have an important effect on the physical properties of the\nring. Thus, we analyze the Fermi energy and magnetization. In the specific case\nof magnetization, we consider two approaches. In the first, we obtain an\nanalytical result for magnetization but without considering rotation. Numerical\nresults showed the de Haas-Van Alphen (dHvA) oscillations. In the second, we\nconsider rotating effects. In addition to the dHvA oscillations, we also verify\nthe Aharonov-Bohm-type (AB) oscillations, which are associated with the\npresence of edge states. We discuss the effects of rotation on the results and\nfind that rotation is responsible for inducing Aharonov-Bohm-type oscillations."
    },
    {
        "anchor": "Andreev reflection in Euler materials: Many previous studies of Andreev reflection have demonstrated that unusual\neffects can occur in media which have a nontrivial bulk topology. Following\nthis line of investigation, we study Andreev reflection in topological Euler\nmaterials by analysing a simple model of a bulk node with a generic winding\nnumber $n\\geq 0$. We find that the magnitudes of the resultant reflection\ncoefficients depend strongly on whether the winding is even or odd. Moreover\nthis parity dependence is reflected in the differential conductance curves,\nwhich are highly suppressed for $n$ even but not $n$ odd. This gives a possible\nroute through which the recently discovered Euler topology could be probed\nexperimentally.",
        "positive": "Design and control of mode interaction in coupled ZnTe optical\n  microcavities: The photonics involving II-VI epitaxial layers was limited so far to\nstructures based on a single planar microcavity. Here, we present double,\nvertically coupled, ZnTe optical microcavities in planar and 3-D photonic\nmolecule geometry. We design the structures with the help of transfer matrix\nmethod calculations and we establish their fabrication technology by molecular\nbeam epitaxy. We characterize the samples by reflectivity spatial mapping and\nstudy them by measurements of angle-integrated and angle-resolved\nphotoluminescence and reflectivity. We efficiently tailor the interaction\nstrength of the cavities optical modes by an adjustment of the spatial\nseparation between the microcavities, their thickness ratio and by the size of\nmicropillars etched out of the planar structure. Coupling constants extracted\nfrom our measurements agree well with those determined in calculations in the\nframe of a tight-binding approach applied to one-dimensional photonic\nstructures."
    },
    {
        "anchor": "Dragging of magnetic domain walls by interlayer exchange: Magnetic domain walls can be moved by spin-polarized currents due to\nspin-transfer torques. This opens the possibility to use them in spintronic\nmemory devices as, e.g., in racetrack storage. Naturally, in miniaturized\ndevices domain walls can get very close to each other and affect each others\ndynamics. In this work we consider two separated domain walls in different\nlayers which interact via an interlayer exchange coupling. One of these walls\nis moved by a spin-polarized current. Depending on several parameters as the\ncurrent density, the interlayer coupling or the pinning potential, the combined\ndynamics of the two domain walls can change very strongly allowing, e.g., for a\ncorrelated motion of the walls. In addition, more subtle effect appear as a\nsuppression of the Walker breakdown accompanied by an increase of the domain\nwall velocity.",
        "positive": "Encoding orbital angular momentum of light in magnets: Breaking the diffraction limit and focusing laser beams to subwavelength\nscale are becoming possible with the help of recent developments in plasmonics.\nSuch subwavelength focusing bridges different length scales of laser beams and\nmatter. Here we consider optical vortex, or laser beam carrying orbital angular\nmomentum (OAM) and discuss potential subwavelength magnetic phenomena induced\nby such laser. On the basis of numerical calculations using\nLandau-Lifshitz-Gilbert equation, we propose two OAM-dependent phenomena\ninduced by optical vortices, generation of radially anisotropic spin waves and\ngeneration of topological defects in chiral magnets. The former could lead to\nthe transient topological Hall effect through the laser-induced scalar spin\nchirality, and the latter reduces the timescale of generating skyrmionic\ndefects by several orders compared to other known means."
    },
    {
        "anchor": "Self-consistent theory of ferromagnetism on the surface of a topological\n  insulator: The Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction between magnetic\nimpurities, mediated by Dirac surface states on the surface of a topological\ninsulator, leads to impurities ferromagnetic ordering. We present a\nself-consistent theory of the ordering, which takes into account a gap in the\nsurface spectrum induced by the exchange field of magnetic impurities. We show\nthat the gap does not change the general structure of RKKY interaction but\nconsiderable influences its strength. This feedback can be both positive and\nnegative, depending on the ratio between the chemical potential and the gap,\nand it qualitatively modifies the temperature dependence of the spin\npolarization of magnetic impurities. The resulting unusual temperature\ndependence can be directly measured in angle resolved photoemission\nspectroscopy (ARPES) and scanning tunneling microscopy (STM) experiments.",
        "positive": "Tuning and Switching a Plasmonic Quantum Dot Sandwich in a Nematic Line\n  Defect: We study the quantum-mechanical effects arising in a single semiconductor\ncore/shell quantum dot controllably sandwiched between two plasmonic nanorods.\nControl over the position and the sandwich confinement structure is achieved by\nthe use of a linear-trap, liquid-crystal line defect and laser tweezers that\npush the sandwich together. This arrangement allows for the study of exciton\nplasmon interactions in a single structure, unaltered by ensemble effects or\nthe complexity of dielectric interfaces. We demonstrate the effect of plasmonic\nconfinement on the photon-antibunching behavior of the quantum dot and its\nluminescence lifetime. The quantum dot behaves as a single emitter when\nnanorods are far away from the quantum dot but shows possible multiexciton\nemission and a significantly decreased lifetime when tightly confined in a\nplasmonic sandwich. These findings demonstrate that liquid crystal defects,\ncombined with laser tweezers, enable a versatile platform to study plasmonic\ncoupling phenomena in a nanoscale laboratory, where all elements can be\narranged almost at will."
    },
    {
        "anchor": "Correction factor in non-diffusive Hall magnetometry: It is demonstrated how the correction factor alpha used in Hall magnetometry\nof localized magnetic field profiles depends on the sample geometry and on the\nelectron mean free path, in the quasi-ballistic and ballistic regimes, for weak\nand strong magnetic field regimes. The frequently used approximation of a\nconstant correction factor close to 1 is generally not justified, especially in\nthe case of bipolar magnetic field profiles and may lead to large errors in the\ndetermination of the magnitude of the magnetic fields. Rather, alpha depends in\na nontrivial way on the parameters of both the magnetic structure and the Hall\ncross.",
        "positive": "On anomalously large nano-scale heat transfer between metals: The non-contact heat transfer between two bodies is more efficient than the\nStefan-Boltzmann law, when the distances are on the nanometer scale (shorter\nthan Wien's wavelength), due to contributions of thermally excited near fields.\nThis is usually described in terms of the fluctuation electrodynamics due to\nRytov, Levin, and co-workers. Recent experiments in the tip-plane geometry have\nreported \"giant\" heat currents between metallic (gold) objects, exceeding even\nthe expectations of Rytov theory. We discuss a simple model that describes the\ndistance dependence of the data and permits to compare to a plate-plate\ngeometry, as in the proximity (or Derjaguin) approximation. We extract an area\ndensity of active channels which is of the same order for the experiments\nperformed by the groups of Kittel (Oldenburg) and Reddy (Ann Arbor). It is\nargued that mechanisms that couple phonons to an oscillating surface\npolarisation are likely to play a role."
    },
    {
        "anchor": "Analytical expression for the harmonic Hall voltages in evaluating spin\n  orbit torques: Solid understanding of current induced torques is key to the development of\ncurrent and voltage controlled magnetization dynamics in ultrathin magnetic\nheterostructures. A versatile technique is needed to evaluate such torques in\nvarious systems. Here we examine the adiabatic (low frequency) harmonic Hall\nvoltage measurement that has been recently developed to study current induced\neffective field that originate from the spin orbit effects. We analytically\nderive a form that can be used to evaluate the harmonic Hall voltages and\nextract relevant parameters in two representative systems, i.e. out of plane\nand in-plane magnetized systems. Contributions from the anomalous Hall and\nplanar Hall effects are considered.",
        "positive": "Operator correlations in a quenched non-Hermitian Luttinger liquid: We study operator correlations of a spinful Luttinger liquid after\nintroducing a non-Hermitian interaction quench, yielding supersonic modes and\ndominant superconducting correlations as signatures of the non-unitary dynamics\nas well as spin-charge separation. A comparative analysis with the Hermitian\ncounterpart, i.e, when the quench is Hermitian, shows a significant difference\nin the behavior of the model. We derive exact expressions for different\noperator correlations and show that the superconducting correlations decay\nslower than the charge and spin-density wave correlations, especially, within\nthe short-time limit, and at the long-time limit all the operator correlations\nmerge differed only by phase factors in the case of non-hermitian interaction\nquench whereas they do not merge in the case of Hermitian interaction quench.\nIn both cases known Luttinger liquid universality is retained at the long time\nlimit. We also analyze how the dynamics of operator correlations vary in the\npresence of anisotropy in the quenching parameters."
    },
    {
        "anchor": "Superconducting Diode Effect Sign Change in Epitaxial Al-InAs Josepshon\n  Junctions: There has recently been a surge of interest in studying the superconducting\ndiode effect (SDE) analogous to semiconducting circuits where the junction\nshows nonreciprocal response depending on the current direction. The SDE could\nbe observed in systems where the time reversal and inversion symmetries are\nbroken. Here, we observe the SDE in epitaxial Al-InAs Josephson junctions (JJs)\nwith strong Rashba spin-orbit coupling (SOC), and show that this effect\nstrongly depends on the orientation of the in-plane magnetic field. In the\npresence of strong magnetic field, we observe a change of sign in the SDE.\nSimulation and measurement of supercurrent suggest that depending on the\nsuperconducting widths, $W_S$, this sign change may not necessarily be related\nto $0-\\pi$ or topological transitions. We find the strongest sign change in\njunctions with narrow $W_S$ is consistent with SOC-induced asymmetry of the\ncritical current under magnetic-field inversion, while in wider $W_S$, the sign\nreversal could be related to $0-\\pi$ transitions and topological\nsuperconductivity",
        "positive": "Discrete Charging in Polysilicon Gates of Single Electron Transistors: Low temperature electron transport measurements of single electron\ntransistors fabricated in advanced CMOS technology with polysilicon gates not\nonly exhibit clear Coulomb blockade behavior but also show a large number of\nadditional conductance fluctuations in the nonlinear regime. By comparison with\nsimulations these features are quantitatively attributed to the effects of\ndiscretely charged islands in the polysilicon gates."
    },
    {
        "anchor": "Quantum statistics of vortices from a dual theory of the XY ferromagnet: We extend the well-known mapping between the easy-plane ferromagnet and\nelectrostatics in $d=2$ spatial dimensions to dynamical and quantum phenomena\nin a $d=2+1$ spacetime. Ferromagnetic vortices behave like quantum particles\nwith an electric charge equal to the vortex number and a magnetic flux equal to\nthe transverse spin of the vortex core. Vortices with half-integer core spin\nexhibit fermionic statistics.",
        "positive": "Fermi Surface Evolution and Anomalous Hall Effect in an Ideal Type-II\n  Weyl Semimetal: Weyl semimetals (WSMs) are three-dimensional topological materials that\nexhibit fascinating properties due to the presence of Weyl nodes in their band\nstructure. However, existing WSMs discovered so far often possess multiple\npairs of Weyl nodes, posing a challenge in disentangling the contributions to\ntransport phenomena from different energy bands. To overcome this challenge, we\nhave identified field-induced ferromagnetic MnBi$_{2-x}$Sb$_{x}$Te$_{4}$ as an\nideal type-II WSM with a single pair of Weyl nodes. By employing a combination\nof quantum oscillations and high-field Hall measurements, we have resolved the\nevolution of Fermi-surface sections as the Fermi level is tuned across the\ncharge neutrality point, precisely matching the band structure of an ideal\ntype-II WSM. Furthermore, the anomalous Hall conductivity exhibits a\nheartbeat-like behavior as the Fermi level is tuned across the Weyl nodes, a\nunique feature previously predicted for a type-II WSM. Our findings establish\nMnBi$_{2-x}$Sb$_{x}$Te$_{4}$ as an ideal platform for further investigation\ninto Weyl physics."
    },
    {
        "anchor": "Thermal rectification and spin-spin coupling of non-reciprocal localized\n  and surface modes: We study the rectification of near-field radiative heat transfer between two\nInSb nano-particles due to the presence of non-reciprocal surface modes in a\nnearby InSb sample when an external magnetic field is applied and its\ndependence on the magnetic field strength. We reveal the spin-spin coupling\nmechanism of the localized particle resonances and the surface mode resonances\nwhich is substantiated by the directional heat flux in the given setup. We\ndiscuss further the interplay of the frequency shift, the propagation length,\nand local density of states on the strength and directionality of the\nrectification as well as the non-reciprocal heating effect of the\nnanoparticles.",
        "positive": "Spin transfer torque in Mn$_3$Ga-based ferrimagnetic tunnel junctions\n  from first principles: We report on first-principles calculations of spin-transfer torque (STT) in\nepitaxial magnetic tunnel junctions (MTJs) based on ferrimagnetic tetragonal\nMn$_3$Ga electrodes, both as analyzer in an Fe/MgO stack, and also in an\nanalogous stack with a second Mn$_3$Ga electrode (instead of Fe) as polarizer.\nSolving the ballistic transport problem (NEGF + DFT) for the nonequilibrium\nspin density in a scattering region extended to over 7.6 nm into the Mn$_3$Ga\nelectrode, we find long-range spatial oscillations of the STT decaying on a\nlength scale of a few tens of angstroms, both in the linear response regime and\nfor finite bias. The oscillatory behavior of the STT in Mn$_3$Ga is robust\nagainst variations in the stack geometry and the applied bias voltage, which\nmay affect the phase and the amplitude of the spatial oscillation, but the wave\nnumber is only responsive to variations in the longitudinal lattice constant of\nMn$_3$Ga (for fixed in-plane geometry) without being commensurate with the\nlattice. Our interpretation of the long-range STT oscillations is based on the\nbulk electronic structure of Mn$_3$Ga, taking also into account the\nspin-filtering properties of the MgO barrier. Comparison to a fully\nMn$_3$Ga-based stack shows similar STT oscillations, but a significant\nenhancement of both the TMR effect at the Fermi level and the STT at the\ninterface, due to resonant tunneling for the mirror-symmetric junction with\nthinner barrier (three monoatomic layers). From the calculated energy\ndependence of the spin-polarized transmissions at 0 V, we anticipate asymmetric\nor symmetric TMR as a function of the applied bias voltage for the Fe-based and\nthe all-Mn$_3$Ga stacks, respectively, which also both exhibit a sign change\nbelow 1 V. In the latter (symmetric) case we expect a TMR peak at zero, which\nis larger for the thinner barriers because of a spin-polarized resonant\ntunneling contribution."
    },
    {
        "anchor": "Theory of transient spectroscopy of multiple quantum well structures: A theory of the transient spectroscopy of quantum well (QW) structures under\na large applied bias is presented. An analytical model of the initial part of\nthe transient current is proposed. The time constant of the transient current\ndepends not only on the emission rate from the QWs, as is usually assumed, but\nalso on the subsequent carrier transport across QWs. Numerical simulation was\nused to confirm the validity of the proposed model, and to study the transient\ncurrent on a larger time scale. It is shown that the transient current is\ninfluenced by the nonuniform distribution of the electric field and related\neffects, which results in a step-like behavior of the current. A procedure of\nextraction of the QW emission time from the transient spectroscopy experiments\nis suggested.",
        "positive": "Single to quadruple quantum dots with tunable tunnel couplings: We prepare a gate-defined quadruple quantum dot to study the gate-tunability\nof single to quadruple quantum dots with finite inter-dot tunnel couplings. The\nmeasured charging energies of various double dots suggest that the dot size is\ngoverned by gate geometry. For the triple and quadruple dots we study\ngate-tunable inter-dot tunnel couplings. Particularly for the triple dot we\nfind that the effective tunnel coupling between side dots significantly depends\non the alignment of the center dot potential. These results imply that the\npresent quadruple dot device has gate performance relevant for implementing\nspin-based four-qubit systems with controllable exchange couplings."
    },
    {
        "anchor": "Direct current driven by ac electric field in quantum wells: It is shown that the excitation of charge carriers by ac electric field with\nzero average driving leads to a direct electric current in quantum well\nstructures. The current emerges for both linear and circular polarization of\nthe ac electric field and depends on the field polarization and frequency. We\npresent a micoscopic model and an analytical theory of such a nonlinear\nelectron transport in quantum wells with structure inversion asymmetry. In such\nsystems, dc current is induced by ac electric field which has both the in-plane\nand out-of-plane components. The ac field polarized in the interface plane\ngives rise to a direct current if the quantum well is subjected to an in-plane\nstatic magnetic field.",
        "positive": "Charge relaxation resistance in the cotunneling regime of multi-channel\n  Coulomb blockade: Violation of Korringa-Shiba relation: We study the low frequency admittance of a small metallic island coupled to a\ngate electrode and to a massive reservoir via a \\emph{multi channel} tunnel\njunction. The ac current is caused by a slowly oscillating gate voltage. We\nfocus on the regime of inelastic cotunneling in which the dissipation of energy\n(the real part of the admittance) is determined by two-electron tunneling with\ncreation of electron-hole pairs on the island. We demonstrate that at finite\ntemperatures but low frequencies the energy dissipation is ohmic whereas at\nzero temperature it is super-ohmic. We find that (i) the charge relaxation\nresistance (extracted from the real part of the admittance) is strongly\ntemperature dependent, (ii) the imaginary and real parts of the admittance do\nnot satisfy the Korringa-Shiba relation. At zero temperature the charge\nrelaxation resistance vanishes in agreement with the recent zero temperature\nanalysis [M. Filippone and C. Mora, Phys. Rev. B {\\bf 86}, 125311 (2012) and P.\nDutt, T. L. Schmidt, C. Mora, and K. Le Hur, Phys. Rev. B {\\bf 87}, 155134\n(2013)]."
    },
    {
        "anchor": "Floquet states in dissipative open quantum systems: We theoretically investigate basic properties of nonequilibrium steady states\nof periodically-driven open quantum systems based on the full solution of the\nMaxwell-Bloch equation. In a resonantly driving condition, we find that the\ntransverse relaxation, also known as decoherence, significantly destructs the\nformation of Floquet states while the longitudinal relaxation does not directly\naffect it. Furthermore, by evaluating the quasienergy spectrum of the\nnonequilibrium steady states, we demonstrate that the Rabi splitting can be\nobserved as long as the decoherence time is as short as one third of the\nRabi-cycle. Moreover, we find that Floquet states can be formed even under\nsignificant dissipation when the decoherence time is substantially shorter than\nthe cycle of driving, once the driving field strength becomes strong enough. In\nan off-resonant condition, we demonstrate that the Floquet states can be\nrealized even in weak field regimes because the system is not excited and the\ndecoherence mechanism is not activated. Once the field strength becomes strong\nenough, the system can be excited by nonlinear processes and the decoherence\nprocess becomes active. As a result, the Floquet states are significantly\ndisturbed by the environment even in the off-resonant condition. Thus, we show\nhere that the suppression of heating is a key condition for the realization of\nFloquet states in both on and off-resonant conditions not only because it\nprevents material damage but also because it contributes to preserving\ncoherence.",
        "positive": "Quantum interference in a\n  superconductor-${\\mathrm{MnBi}}_{2}{\\mathrm{Te}}_{4}$-superconductor\n  Josephson junction: We study the transport properties of a Josephson junction consisting of two\nidentical $s$-wave superconductors separated by an even-layer\n${\\mathrm{MnBi}}_{2}{\\mathrm{Te}}_{4}$ (MBT). Using recursive Green's function\nmethod, we calculate the supercurrent in the presence of a perpendicular\nmagnetic field and find that its quantum interference exhibits distinct\npatterns when the MBT is in different magnetic states. In the antiferromagnetic\nstate, the MBT is an axion insulator supporting an extended \"hinge\"\nsupercurrent, which leads to a sinusoidal interference pattern decaying with\nthe field strength. In the ferromagnetic state, the MBT is a Chern insulator\nand the unbalanced chiral supercurrents on opposite edges give rise to a highly\nasymmetric interference pattern. If the MBT turns into a metal as the Fermi\nlevel is tuned into the conduction band, the interference exhibits a Fraunhofer\npattern due to the uniformly distributed bulk supercurrent. Our work unravels a\nstrong indicator to identify different phases in the MBT and can be verified\ndirectly by experiments."
    },
    {
        "anchor": "Magnons versus electrons in thermal spin transport through metallic\n  interfaces: We develop a theory for spin transport in magnetic metals that treats the\ncontribution of magnons and electrons on equal footing. As an application we\nconsider thermally-driven spin injection across an interface between a magnetic\nmetal and a normal metal, i.e., the spin-dependent Seebeck effect. We show that\nthe ratio between magnonic and electronic contribution scales as\n$\\sqrt{T/T_C}T_F/T_C$, with the Fermi temperature $T_F$ and the Curie\ntemperature $T_C$. Since, typically, $T_C \\ll T_F$, the magnonic contribution\nmay dominate the thermal spin injection, even though the interface is more\ntransparent for electronic spin current.",
        "positive": "General considerations of the electrostatic boundary conditions in oxide\n  heterostructures: This is a book chapter that covers general considerations of the\nelectrostatic stability of oxide surfaces and interfaces."
    },
    {
        "anchor": "Wave excitations of drifting two-dimensional electron gas under strong\n  inelastic scattering: We have analyzed low-temperature behavior of two-dimensional electron gas in\npolar heterostructures subjected to a high electric field. When the optical\nphonon emission is the fastest relaxation process, we have found existence of\ncollective wave-like excitations of the electrons. These wave-like excitations\nare periodic in time oscillations of the electrons in both real and momentum\nspaces. The excitation spectra are of multi-branch character with considerable\nspatial dispersion. There are one acoustic-type and a number of optical-type\nbranches of the spectra. Their small damping is caused by quasi-elastic\nscattering of the electrons and formation of relevant space charge. Also there\nexist waves with zero frequency and finite spatial periods - the standing\nwaves. The found excitations of the electron gas can be interpreted as\nsynchronous in time and real space manifestation of well-known\noptical-phonon-transient-time-resonance. Estimates of parameters of the\nexcitations for two polar heterostructures, GaN/AlGaN and ZnO/MgZnO, have shown\nthat excitation frequencies are in THz-frequency range, while standing wave\nperiods are in sub-micrometer region.",
        "positive": "Green's functions and DOS for some 2D lattices: In this note we present the Green's functions and density of states for the\nmost frequently encountered 2D lattices: square, triangular, honeycomb, kagome,\nand Lieb lattice. Though the results are well know, we hope that their\nderivation performed in a uniform way is of some pedagogical value."
    },
    {
        "anchor": "Dawn of Cavity Spintronics: Merging the progress of spintronics with the advancement in cavity quantum\nelectrodynamics and cavity polaritons, a new field of Cavity Spintronics is\nforming, which connects some of the most exciting modern physics, such as\nquantum information and quantum optics, with one of the oldest science on the\nearth, the magnetism.",
        "positive": "Transport gap engineering by contact geometry in graphene nanoribbons:\n  Experimental and theoretical studies on artificial materials: Electron transport in small graphene nanoribbons is studied by microwave\nemulation experiments and tight-binding calculations. In particular, it is\ninvestigated under which conditions a transport gap can be observed. Our\nexperiments provide evidence that armchair ribbons of width $3m+2$ with integer\n$m$ are metallic and otherwise semiconducting, whereas zigzag ribbons are\nmetallic independent of their width. The contact geometry, defining to which\natoms at the ribbon edges the source and drain leads are attached, has strong\neffects on the transport. If leads are attached only to the inner atoms of\nzigzag edges, broad transport gaps can be observed in all armchair ribbons as\nwell as in rhomboid-shaped zigzag ribbons. All experimental results agree\nqualitatively with tight-binding calculations using the nonequilibrium Green's\nfunction method."
    },
    {
        "anchor": "Plasmon-mediated superradiance near metal nanostructures: We develop a theory of cooperative emission of light by an ensemble of\nemitters, such as fluorescing molecules or semiconductor quantum dots, located\nnear a metal nanostructure supporting surface plasmon. The primary mechanism of\ncooperative emission in such systems is resonant energy transfer between\nemitters and plasmons rather than the Dicke radiative coupling between\nemitters. We identify two types of plasmonic coupling between the emitters, (i)\nplasmon-enhanced radiative coupling and (ii) plasmon-assisted nonradiative\nenergy transfer, the competition between them governing the structure of system\neigenstates. Specifically, when emitters are removed by more than several nm\nfrom the metal surface, the emission is dominated by three superradiant states\nwith the same quantum yield as a single emitter, resulting in a drastic\nreduction of ensemble radiated energy, while at smaller distances cooperative\nbehavior is destroyed by nonradiative transitions. The crossover between two\nregimes can be observed in distance dependence of ensemble quantum efficiency.\nOur numerical calculations incorporating direct and plasmon-assisted\ninteractions between the emitters indicate that they do not destroy the\nplasmonic Dicke effect.",
        "positive": "Anomalous temperature dependence of the the spin-flip thermalization\n  time between the dark and bright exciton states in silicon nanocrystals: Silicon nanocrystals are studied by time-resolved fluorescence spectroscopy.\nAfter laser excitation the bright and dark exciton ground state levels are\npopulated at random, but subsequently the decay curves reveal a thermalization\nbetween these levels. The characteristic thermalization time is found to be\napproximately 100 ns for temperatures below 100 K and surprisingly increases\nfor higher temperatures. The decay curves are analyzed using a simple two-state\nmodel for the bright and dark exciton ground states."
    },
    {
        "anchor": "Solid state Stern-Gerlach spin-splitter for magnetic field sensoring,\n  spintronics, and quantum computing: We show that the edge of a two-dimensional topological insulator can be used\nto construct a solid state Stern-Gerlach spin-splitter. By threading such a\nStern-Gerlach apparatus with a magnetic flux, Ahranov-Bohm like interference\neffects are introduced. Using ferromagnetic leads, the setup can be used to\nboth measure magnetic flux and as a spintronics switch. With normal metallic\nleads a switchable spintronics NOT-gate can be implemented. Furthermore, we\nshow that a sequence of such devices can be used to construct a single-qubit\n$SU(2)$-gate, one of the two gates required for a universal quantum computer.\nThe field sensitivity, or switching field, $b$ is related to the device\ncharacteristic size $r$ through $b = \\frac{\\hbar}{qr^2}$, with $q$ the unit of\nelectric charge.",
        "positive": "Wigner-Poisson statistics of topological transitions in a Josephson\n  junction: The phase-dependent bound states (Andreev levels) of a Josephson junction can\ncross at the Fermi level, if the superconducting ground state switches between\neven and odd fermion parity. The level crossing is topologically protected, in\nthe absence of time-reversal and spin-rotation symmetry, irrespective of\nwhether the superconductor itself is topologically trivial or not. We develop a\nstatistical theory of these topological transitions in an N-mode quantum-dot\nJosephson junction, by associating the Andreev level crossings with the real\neigenvalues of a random non-Hermitian matrix. The number of topological\ntransitions in a 2pi phase interval scales as sqrt(N) and their spacing\ndistribution is a hybrid of the Wigner and Poisson distributions of\nrandom-matrix theory."
    },
    {
        "anchor": "Emergence of topological semimetals in gap closing in semiconductors\n  without inversion symmetry: A band gap for electronic states in crystals governs various properties of\nsolids, such as transport, optical and magnetic properties. Its estimation and\ncontrol have been an important issue in solid state physics. The band gap can\nbe controlled externally by various parameters, such as pressure, atomic\ncompositions and external field. Sometimes, the gap even collapses by tuning\nsome parameter. In the field of topological insulators, such closing of the gap\nat a time-reversal invariant momentum indicates a band inversion, i.e. it leads\nto a topological phase transition from a normal insulator to a topological\ninsulator. Here we show that the gap losing in inversion-asymmetric crystals is\nuniversal, in the sense that the gap closing always leads either to a Weyl\nsemimetal or a nodal-line semimetal, from an exhaustive study on possible space\ngroups. We here consider three-dimensional spinful systems with time-reversal\nsymmetry. The space group of the system and the wavevector at the gap closing\nuniquely determine which possibility occurs and where the gap-closing points or\nlines lie in the wavevector space after closing of the gap. In particular, we\nshow that an insulator-to-insulator transition never happens, which is in sharp\ncontrast with inversion-symmetric systems.",
        "positive": "Transient response under ultrafast interband excitation of an intrinsic\n  graphene: The transient evolution of carriers in an intrinsic graphene under ultrafast\nexcitation, which is caused by the collisionless interband transitions, is\nstudied theoretically. The energy relaxation due to the quasielastic acoustic\nphonon scattering and the interband generation-recombination transitions due to\nthermal radiation are analyzed. The distributions of carriers are obtained for\nthe limiting cases when carrier-carrier scattering is negligible and when the\nintercarrier scattering imposes the quasiequilibrium distribution. The\ntransient optical response (differential reflectivity and transmissivity) on a\nprobe radiation and transient photoconductivity (response on a weak dc field)\nappears to be strongly dependent on the relaxation and recombination dynamics\nof carriers."
    },
    {
        "anchor": "Latent Su-Schrieffer-Heeger models: The Su-Schrieffer-Heeger (SSH) chain is the reference model of a\none-dimensional topological insulator. Its topological nature can be explained\nby the quantization of the Zak phase, due to reflection symmetry of the unit\ncell, or of the winding number, due to chiral symmetry. Here, we harness recent\ngraph-theoretical results to construct families of setups whose unit cell\nfeatures neither of these symmetries, but instead a so-called latent or hidden\nreflection symmetry. This causes the isospectral reduction -- akin to an\neffective Hamiltonian -- of the resulting lattice to have the form of an SSH\nmodel. As we show, these latent SSH models exhibit features such as multiple\ntopological transitions and edge states, as well as a quantized Zak phase.\nRelying on a generally applicable discrete framework, we experimentally\nvalidate our findings using electric circuits.",
        "positive": "Tailoring optical response of a hybrid comprising a quantum dimer\n  emitter strongly coupled to a metal nanoparticle: We study theoretically the optical response of a nanohybrid comprising a\nsymmetric quantum dimer emitter coupled to a metal nanoparticle (MNP). The\ninteractions between the exitonic transitions in the dimer and the plasmons in\nthe MNP lead to novel effects in the composite's input-output characteristics\nfor the light intensity and the absorption spectrum, which we study in the\nlinear and nonlinear regimes. We fnd that the exciton-plasmon hybridization\nleads to optical bistability and hysteresis for the one-exciton transition and\nenhancement of excitation for the two-exciton transition. The latter leads to a\nsignifcant decrease of the field strength needed to saturate the system. In the\nlinear regime, the absortion spectrum has a dispersive (Fano-like) line shape.\nThe spectral position and shape of this spectrum depend on the detuning of the\ndimer's one-exciton resonance relative to the plasmon resonance. Upon\nincreasing the applied field intensity to the nonlinear regime, the Fano-like\nsingularities in the absorption spectra are smeared and they disappear due to\nthe saturation of the dimer, which leads to the MNP dominating the spectrum.\nThe above effects, for which we provide physical explanations, allow one to\ntailor the Fano-like shape of the absorption spectrum, by changing either the\ndetuning or the input power."
    },
    {
        "anchor": "Theory of absorption lineshape in monolayers of transition metal\n  dichalcogenides: The linear absorption spectra in monolayers of transition metal\ndichalcogenides show pronounced signatures of the exceptionally strong\nexciton-phonon interaction in these materials. To account for both exciton and\nphonon physics in such optical signals, we compare different theoretical\nmethods to calculate the absorption spectra using the example of\n$\\mathrm{MoSe_2}$. In this paper, we derive the equations of motion for the\npolarization either using a correlation expansion up to 4th Born approximation\nor a time convolutionless master equation. We show that the Born approximation\nmight become problematic when not treated in high enough order, especially at\nhigh temperatures. In contrast, the time convolutionless formulation gives\nsurprisingly good results despite its simplicity when compared to higher-order\ncorrrelation expansion and therefore provides a powerful tool to calculate the\nlineshape of linear absorption spectra in the very popular monolayer materials.",
        "positive": "Type-I hyperbolic metasurfaces for highly-squeezed designer polaritons\n  with negative group velocity: Hyperbolic polaritons in van der Waals materials and metamaterial\nheterostructures provide unprecedented control over light-matter interaction at\nthe extreme nanoscale. Here, we propose a concept of type-I hyperbolic\nmetasurface supporting highly-squeezed magnetic designer polaritons, which act\nas magnetic analogues to hyperbolic polaritons in the hexagonal boron nitride\n(h-BN) in the first Reststrahlen band. Comparing with the natural h-BN, the\nsize and spacing of the metasurface unit cell can be readily scaled up (or\ndown), allowing for manipulating designer polaritons in frequency and in space\nat will. Experimental measurements display the cone-like hyperbolic dispersion\nin the momentum space, associating with an effective refractive index up to 60\nand a group velocity down to 1/400 of the light speed in vacuum. By tailoring\nthe proposed metasurface, we experimentally demonstrate an ultra-compact (with\na footprint shrunken by 3600 times) integrated designer polariton circuit\nincluding high-transmission 90{\\deg} sharp bending waveguides and waveguide\nsplitters. The designed metasurface with a low profile, lightweight, and ease\nof access, can serve as an alternatively promising platform for emerging\npolaritonics, and may find many other potential applications, such as\nwaveguiding, sensing, subdiffraction focusing/imaging, low-threshold Cherenkov\nradiation, strong magnetic transition enhancement, wireless energy transfer,\nand so forth."
    },
    {
        "anchor": "Electrical power dissipation in carbon nanotubes on single crystal\n  quartz and amorphous SiO2: Heat dissipation in electrically biased semiconducting carbon nanotubes\n(CNTs) on single crystal quartz and amorphous SiO2 is examined with temperature\nprofiles obtained by spatially resolved Raman spectroscopy. Despite the\ndifferences in phonon velocities, thermal conductivity and van der Waals\ninteractions with CNTs, on average, heat dissipation into single crystal quartz\nand amorphous SiO2 is found to be similar. Large temperature gradients and\nlocal hot spots often observed underscore the complexity of CNT temperature\nprofiles and may be accountable for the similarities observed.",
        "positive": "Relaxation of electrons in quantum-confined states in Pb/Si(111) thin\n  films from master equation with first-principles-derived rates: Atomically thin films of Pb on Si(111) provide an experimentally tunable\nsystem comprising a highly structured electronic density of states. The\nlifetime of excited electrons in these states is limited by both\nelectron-electron (e-e) and electron-phonon (e-ph) scattering. We employ the\ndescription by a master equation for the electronic occupation numbers to\nanalyze the relative importance of both scattering mechanisms. The electronic\nand phononic band structures, as well as the matrix elements for\nelectron-phonon coupling within deformation potential theory were obtained from\ndensity functional calculations, thus taking into account quantum confinement\neffects. For the relaxation dynamics, the contribution of impact ionization\nprocesses to the lifetime is estimated from the imaginary part of the\nelectronic self-energy calculated in the GW approximation. By numerically\nsolving rate equations for the occupations of the Pb-derived electronic states\ncoupled to a phononic heat bath, we are able to follow the distribution of the\nelectronic excitation energy to the various modes of Pb lattice vibrations.\nWhile e-e scattering is the dominant relaxation mechanism, we demonstrate that\nthe e-ph scattering is highly phonon-mode-specific, with a large contribution\nfrom surface phonons. At electron energies of about 0.3 eV above the Fermi\nsurface, a 'phonon bottleneck' characteristic of relaxation in nanostructures\nwith well-separated electronic states is observed. The time scales extracted\nfrom the simulations are compared to data from pump-probe experiments using\ntime-resolved two-photon photoemission."
    },
    {
        "anchor": "Effect of random anisotropy in stabilization of topological chiral\n  textures: Ever increasing demand of skyrmion manipulation in nanodevices has brought up\ninteresting research to 8 understand the stabilization of these topologically\nprotected chiral structures. To understand the actual shape 9 and size of\nskyrmion observed experimentally, we have performed micromagnetic simulations\nto investigate 10 skyrmion stabilization in presence of random anisotropy in\nmagnetic thin film system. Previous experimental 11 reports of skyrmion imaging\nin thin films depicts that the skyrmion shape is not perfectly circular. Here\nwe 12 show via simulations that the shape of a skyrmion can get distorted due\nto the presence of different local 13 anisotropy energy. The values of uniaxial\nanisotropy constant (Ku) and random aniostropy constant (Kr) 14 are varied to\nunderstand the change in shape and size of a skyrmion and an antiskyrmion\nstabilized in a 15 square magnetic nanoelement. The skyrmion shape gets\ndistorted and the size gets constant for high random 16 anisotropy energy in\nthe system.",
        "positive": "Insights into electron transport in a ferroelectric tunnel junction: The success of a ferroelectric tunnel junction (FTJ) depends on the asymmetry\nof electron tunneling as given by the tunneling electroresistance (TER) effect.\nThis characteristic is mainly assessed considering three transport mechanisms:\ndirect tunneling, thermionic emission, and Fowler-Nordheim tunneling. Here, by\nanalyzing the effect of temperature on TER, we show that taking into account\nonly these mechanisms may not be enough in order to fully characterize the\nperformance of FTJ devices. We approach the electron tunneling in FTJ with the\nnon-equilibrium Green function (NEGF) method, which is able to overcome the\nlimitations affecting the three mechanisms mentioned above. We bring evidence\nthat the performance of FTJs is also affected by temperature, in a non-trivial\nway, via resonance (Gamow-Siegert) states, which are present in the electron\ntransmission probability and are usually situated above the barrier. Although\nthe NEGF technique does not provide direct access to the wavefunctions, we show\nthat, for single-band transport, one can find the wavefunction at any given\nenergy and in particular at resonant energies in the system."
    },
    {
        "anchor": "Enhanced Photocurrent Efficiency of a Carbon Nanotube\n  Electromagnetically Coupled to a Photonic Structure: We present photocurrent power-enhancement calculations of a carbon nanotube\np-n junction electromagnetically coupled to a highly-efficient photonic\nstructure. Particular attention is paid to a GaAs photonic structure\nspecifically modified to increase the intensity of infrared light onto the\nnanotube region for effective energy conversion. Using finite-difference\ntime-domain calculations, we compute a significant increase in electric field\nintensity in the nanotube region which enables an estimation of power\nefficiency. These results demonstrate the potential of using a photonic\nstructure to couple large-scale infrared sources with carbon nanotubes while\nstill retaining all the unique optoelectronic properties found at the\nnanoscale.",
        "positive": "Monolayer Semiconductor Auger Detector: Auger recombination in semiconductors is a many-body phenomenon in which\nrecombination of electrons and holes is accompanied by excitation of other\ncharge carriers. Being nonradiative, it is detrimental to light emission. The\nexcess energy of the excited carriers is normally rapidly converted to heat,\nmaking Auger processes difficult to probe directly. Here, we employ a technique\nin which the Auger-excited carriers are detected by their ability to tunnel out\nof the semiconductor through a thin barrier, generating a current. We employ\nvertical van der Waals (vdW) heterostructures with monolayer WSe2 as the\nsemiconductor and the wide band gap hexagonal boron nitride (hBN) as the tunnel\nbarrier to preferentially transmit high-energy Auger-excited carriers to a\ngraphite electrode. The unambiguous signatures of Auger processes are a rise in\nthe photocurrent when excitons are created by resonant excitation, and negative\ndifferential photoconductance resulting from the shifts of the exciton\nresonances with voltage. We detect holes Auger-excited by both neutral and\ncharged excitons, and find that the Auger scattering is surprisingly strong\nunder weak excitation. The selective extraction of Auger carriers at low,\ncontrolled carrier densities that is enabled by vdW heterostructures\nillustrates an important addition to the techniques available for probing\nrelaxation processes in 2D materials."
    },
    {
        "anchor": "Chiral skyrmions in cubic helimagnet films: the role of uniaxial\n  anisotropy: This paper reports on magnetometry and magnetoresistance measurements of MnSi\nepilayers performed in out-of-plane magnetic fields. We present a theoretical\nanalysis of the chiral modulations that arise in confined cubic helimagnets\nwhere the uniaxial anisotropy axis and magnetic field are both out-of-plane. In\ncontrast to in-plane field measurements (Wilson et al., Phys. Rev. B 86, 144420\n(2012)), the hard-axis uniaxial anisotropy in MnSi/Si(111) increases the energy\nof (111)-oriented skyrmions and in-plane helicoids relative to the cone phase,\nand makes the cone phase the only stable magnetic texture below the saturation\nfield. While induced uniaxial anisotropy is important in stabilizing skyrmion\nlattices and helicoids in other confined cubic helimagnets, the particular\nanisotropy in MnSi/Si(111) entirely suppresses these states in an out-of-plane\nmagnetic field. However, it is predicted that isolated skyrmions with enlarged\nsizes exist in MnSi/Si(111) epilayers in a broad range of out-of-plane magnetic\nfields.",
        "positive": "Impact of indirect transitions on valley polarization in WS$_2$ and\n  WSe$_2$: Controlling the momentum of carriers in semiconductors, known as valley\npolarization, is a new resource for optoelectronics and information\ntechnologies. Materials exhibiting high polarization are needed for\nvalley-based devices. Few-layer WS$_2$ shows a remarkable spin-valley\npolarization above 90%, even at room temperature. In stark contrast,\npolarization is absent for few-layer WSe$_2$ despite the expected material\nsimilarities. Here, we explain the origin of valley polarization in both\nmaterials based on the interplay between two indirect optical transitions. We\nshow that the relative energy minima at the $\\Lambda$- and K-valleys in the\nconduction band determine the spin-valley polarization of the direct K-K\ntransition. Polarization appears as the energy of the K-valley rises above the\n$\\Lambda$-valley as a function of temperature and number of layers. Our results\nadvance the understanding of the high spin-valley polarization in WS$_2$. This\ninsight will impact the design of both passive and tunable valleytronic devices\noperating at room temperature."
    },
    {
        "anchor": "Ballistic transport through quantum point contacts of multi-orbital\n  oxides: Linear and non-linear transport properties through an atomic-size point\ncontact based on oxides two-dimensional electron gas is examined using the\ntight-binding method and the $\\mathbf{k\\cdot p}$ approach. The ballistic\ntransport is analyzed in contacts realized at the (001) interface between band\ninsulators $LaAlO_3$ and $SrTiO_3$ by using the Landauer-B\\\"uttiker method for\nmany sub-bands derived from three Ti 3d orbitals ($d_{yz}$, $d_{zx}$ and\n$d_{xy}$) in the presence of an out-of-plane magnetic field. We focus\nespecially on the role played by the atomic spin-orbit coupling and the\ninversion symmetry breaking term pointing out three transport regimes: the\nfirst, at low energies, involving the first $d_{xy}$-like sub-bands, where the\nconductance quantization is robust; a second one, at intermediate energies,\nentailing further $d_{xy}$-like sub-bands, where the sub-band splitting induced\nby the magnetic field is quenched; the third one, where the mixing between\nlight $d_{xy}$-like, heavy $d_{yz}$-like and $d_{zx}$-like sub-bands is so\nstrong that the conductance plateaus turn out to be very narrow. Very good\nagreement is found with recent experiments exploring the transport properties\nat low energies.",
        "positive": "Temperature effect in the conductance of hydrogen molecule: We present a many-body calculation for the conductance of a conducting bridge\nof a simple hydrogen molecule between $Pt$ electrodes.The experimental results\nshowed that the conductance $G=dI/dV$ has the maximum value near the quantum\nunit $G_{0}=2e^{2}/h$.\n  The $I-V$ dependence presents peak and dip and we consider that the\nelectron-phonon interaction is responsible for this behavior. At T=0 there is a\nstep in this dependence for the energy of phonons $\\omega_{0}$ which satisfies\n$eV=\\omega_{0}$. We calculated the conductance at finite temperature and showed\nthat $dG(T)/dV\\propto 1/4T\\cosh^{2}\\frac{eV-\\omega_{0}}{2T}$."
    },
    {
        "anchor": "Optical nonlinearities in the excited carrier density of atomically thin\n  transition metal dichalcogenides: In atomically thin semiconductors based on transition metal dichalcogenides,\nphotoexcitation can be used to generate high densities of electron-hole pairs.\nDue to optical nonlinearities, which originate from Pauli blocking and\nmany-body effects of the excited carriers, the generated carrier density will\ndeviate from a linear increase in pump fluence. In this paper, we use a\ntheoretical approach that combines results from ab-initio electronic-state\ncalculations with a many-body treatment of optical excitation to describe\nnonlinear absorption properties and the resulting excited carrier dynamics. We\ndetermine the validity range of a linear approximation for the excited carrier\ndensity vs. pump power and identify the role and magnitude of optical\nnonlinearities at elevated excitation carrier densities for MoS2, MoSe2, WS2,\nand WSe2 considering various excitation conditions. We find that for\nabove-band-gap photoexcitation, the use of a linear absorption coefficient of\nthe unexcited system can strongly underestimate the achievable carrier density\nfor a wide range of pump fluences due to many-body renormalizations of the\ntwo-particle density-of-states.",
        "positive": "Unconventional sequence of correlated Chern insulators in magic-angle\n  twisted bilayer graphene: The interplay between strong electron-electron interactions and band topology\ncan lead to novel electronic states that spontaneously break symmetries. The\ndiscovery of flat bands in magic-angle twisted bilayer graphene (MATBG) with\nnontrivial topology has provided a unique platform in which to search for new\nsymmetry-broken phases. Recent scanning tunneling microscopy and transport\nexperiments have revealed a sequence of topological insulating phases in MATBG\nwith Chern numbers $C=\\pm 3, \\, \\pm 2, \\, \\pm 1$ near moir\\'e band filling\nfactors $\\nu = \\pm 1, \\, \\pm 2, \\, \\pm 3$, corresponding to a simple pattern of\nflavor-symmetry-breaking Chern insulators. Here, we report high-resolution\nlocal compressibility measurements of MATBG with a scanning single electron\ntransistor that reveal a new sequence of incompressible states with unexpected\nChern numbers observed down to zero magnetic field. We find that the Chern\nnumbers for eight of the observed incompressible states are incompatible with\nthe simple picture in which the $C= \\pm 1$ bands are sequentially filled. We\nshow that the emergence of these unusual incompressible phases can be\nunderstood as a consequence of broken translation symmetry that doubles the\nmoir\\'e unit cell and splits each $C=\\pm 1$ band into a $C=\\pm 1$ band and a\n$C=0$ band. Our findings significantly expand the known phase diagram of MATBG,\nand shed light onto the origin of the close competition between different\ncorrelated phases in the system."
    },
    {
        "anchor": "Nonlinear response in overlapping and separated Landau levels of GaAs\n  quantum wells: We have studied magnetotransport properties of a high-mobility\ntwo-dimensional electron system subject to weak electric fields. At low\nmagnetic field $B$, the differential resistivity acquires a correction $\\delta\nr \\propto -\\lambda^2 j^2/B^2$, where $\\lambda$ is the Dingle factor and $j$ is\nthe current density, in agreement with theoretical predictions. At higher\nmagnetic fields, however, $\\delta r$ becomes $B$-independent, $\\delta r \\propto\n-j^2$. While the observed change in behavior can be attributed to a crossover\nfrom overlapping to separated Landau levels, full understanding of this\nbehavior remains a subject of future theories.",
        "positive": "Flux-periodic supercurrent oscillations in an Aharonov-Bohm-type\n  nanowire Josephson junction: Phase winding effects in hollow semiconductor nanowires with superconducting\nshells have been proposed as a route to engineer topological superconducting\nstates. We investigate GaAs/InAs core/shell nanowires with half-shells of\nepitaxial aluminium as a potential platform for such devices, where the thin\nInAs shell confines the electron wave function around the GaAs core. With\nnormal contacts we observed pronounced $h/e$ flux periodic oscillations in the\nmagnetoconductance, indicating the presence of a tubular conductive channel in\nthe InAs shell. Conversely, the switching current in Josephson junctions\noscillates with approximately half that period, i.e. $h/2e$, indicating\ntransport via Andreev transport processes in the junction enclosing threading\nmagnetic flux. On these structures, we systematically studied the gate-,\nfield-, and temperature-dependent evolution of the supercurrent. Results\nindicate that Andreev transport processes can occur about the wire\ncircumference indicating full proximitization of the InAs shell from the\nhalf-shell superconducting contacts."
    },
    {
        "anchor": "Multipath optical recombination of intervalley dark excitons and trions\n  in monolayer WSe$_2$: Excitons and trions (or exciton-polarons) in transition metal dichalcogenides\n(TMDs) are known to decay predominantly through intravalley transitions.\nElectron-hole recombination across different valleys can also play a\nsignificant role in the excitonic dynamics, but intervalley transitions are\nrarely observed in monolayer TMDs, because they violate the conservation of\nmomentum. Here we reveal the intervalley recombination of dark excitons and\ntrions through more than one path in monolayer WSe$_2$. We observe the\nintervalley dark excitons, which can recombine by the assistance of defect\nscattering or chiral-phonon emission. We also reveal that a trion can decay in\ntwo distinct paths - through intravalley or intervalley electron-hole\nrecombination - into two different final valley states. Although these two\npaths are energy degenerate, we can distinguish them by lifting the valley\ndegeneracy under a magnetic field. In addition, the intra- and inter-valley\ntrion transitions are coupled to zone-center and zone-corner chiral phonons,\nrespectively, to produce distinct phonon replicas. The observed multipath\noptical decays of dark excitons and trions provide much insight into the\ninternal quantum structure of trions and the complex excitonic interactions\nwith defects and chiral phonons in monolayer valley semiconductors.",
        "positive": "Topography induced optical spectral shifts and finite size effect of\n  focal spot: We observe topography induced spectral shifts using high resolution grating\nspectrometers which we attribute to the fact that the focal spot has a finite\nsize. The topography induced spectral shifts depend on spectrometer grating\norientation and numerical aperture of the microscope objective. This is\ndemonstrated by spectroscopic imaging trenches in GaAs in directions parallel\nand perpendicular the spectrometer entrance slit. Differences along the two\ndirections of the LO phonon band show that the spectral shift is due to the\nvariation of the grating angle across the non uniform illuminated focal spot\ncaused by topography. Alignment errors of the optical axis lead to additional\nspectral shifts. Topography induced spectral shifts can be detected by\nrecording spectra by scanning the sample in two perpendicular orientations with\nrespect to the spectrometer entrance slit."
    },
    {
        "anchor": "Collective eigenstates of emission in an N-entity heterostructure and\n  the evaluation of its Green tensors and self-energy components: Our understanding of emission from a collection of emitters strongly\ninteracting among them and also with other polarizable matter in proximity has\nbeen approximated by independent emission from the emitters. This is primarily\ndue to our inability to evaluate the self-energy matrices and the collective\neigenstates of emitters in heterogeneous ensembles. A method to evaluate the\nself-energy matrices that is not limited by the geometry and the material\ncomposition is presented here to understand and exploit such collective\nexcitations. Numerical evaluations using this method are used to highlight the\nsignificant differences between independent and the collective modes of\nemission in heterostructures. A set of n emitters driving each other and m\nother polarizable entities, where N=m+n, is used to represent the coupled\nsystem of a generalized geometry in a volume integral approach. Closed form\nrelations between the Green tensors of entity pairs in free space and their\ncorrespondents in a heterostructure are derived concisely. This is made\npossible for general geometries because the global matrices consisting of all\nfree-space Green dyads are subject to conservation laws. The self-energy matrix\nof the emitters can then be assembled using the evaluated Green tensors of the\nheterostructure, but a decomposition of its components into their radiative and\nnon-radiative decay contributions is non-trivial. This is accomplished using\nmatrix decomposition identities applied to the global matrices containing all\nfree-space dyads. The relations to compute the observables of the eigenstates\n(such as quantum efficiency, power/energy of emission, radiative and\nnon-radiative decay rates) are presented. We conclude with a note on extension\nof this method to collective excitations that also include strong interactions\nwith a surface in the near-field.",
        "positive": "Edge plasmon-polaritons on isotropic semi-infinite conducting sheets: From a three-dimensional boundary value problem for the time harmonic\nclassical Maxwell equations, we derive the dispersion relation for a surface\nwave, the edge plasmon-polariton (EP), that is localized near and propagates\nalong the straight edge of a planar, semi-infinite sheet with a spatially\nhomogeneous, scalar conductivity. The sheet lies in a uniform and isotropic\nmedium; and serves as a model for some two-dimensional (2D) conducting\nmaterials such as the doped monolayer graphene. We formulate a homogeneous\nsystem of integral equations for the electric field tangential to the plane of\nthe sheet. By the Wiener-Hopf method, we convert this system to coupled\nfunctional equations on the real line for the Fourier transforms of the fields\nin the surface coordinate normal to the edge, and solve these equations\nexactly. The derived EP dispersion relation smoothly connects two regimes: a\nlow-frequency regime, where the EP wave number, $q$, can be comparable to the\npropagation constant, $k_0$, of the ambient medium; and the nonretarded\nfrequency regime in which $|q|\\gg |k_0|$. Our analysis indicates two types of\n2D surface plasmon-polaritons on the sheet away from the edge. We extend the\nformalism to the geometry of two coplanar sheets."
    },
    {
        "anchor": "Josephson effect through an anisotropic magnetic molecule: We study the Josephson effect through a magnetic molecule with anisotropic\nproperties. Performing calculations in the tunneling regime, we show that the\nexchange coupling between the electron spin on the molecule and the molecular\nspin can trigger a transition from the $\\pi$ state to the 0 state, and we study\nhow the spin anisotropy affects this transition. We show that the behavior of\nthe critical current as a function of an external magnetic field can give\naccess to valuable information about the spin anisotropy of the molecule.",
        "positive": "Measuring frequency fluctuations in nonlinear nanomechanical resonators: Advances in nanomechanics within recent years have demonstrated an always\nexpanding range of devices, from top-down structures to appealing bottom-up\nMoS$_2$ and graphene membranes, used for both sensing and component-oriented\napplications. One of the main concerns in all of these devices is frequency\nnoise, which ultimately limits their applicability. This issue has attracted a\nlot of attention recently, and the origin of this noise remains elusive up to\ndate. In this Letter we present a very simple technique to measure frequency\nnoise in nonlinear mechanical devices, based on the presence of bistability. It\nis illustrated on silicon-nitride high-stress doubly-clamped beams, in a\ncryogenic environment. We report on the same $T/f$ dependence of the frequency\nnoise power spectra as reported in the literature. But we also find unexpected\n{\\it damping fluctuations}, amplified in the vicinity of the bifurcation\npoints; this effect is clearly distinct from already reported nonlinear\ndephasing, and poses a fundamental limit on the measurement of bifurcation\nfrequencies. The technique is further applied to the measurement of frequency\nnoise as a function of mode number, within the same device. The relative\nfrequency noise for the fundamental flexure $\\delta f/f_0$ lies in the range\n$0.5 - 0.01~$ppm (consistent with literature for cryogenic MHz devices), and\ndecreases with mode number in the range studied. The technique can be applied\nto {\\it any types} of nano-mechanical structures, enabling progresses towards\nthe understanding of intrinsic sources of noise in these devices."
    },
    {
        "anchor": "Topological semimetal phase with exceptional points in one-dimensional\n  non-Hermitian systems: Energy bands of non-Hermitian crystalline systems are described in terms of\nthe generalized Brillouin zone (GBZ) having unique features which are absent in\nHermitian systems. In this paper, we show that in one-dimensional non-Hermitian\nsystems with both sublattice symmetry and time-reversal symmetry such as the\nnon-Hermitian Su-Schrieffer-Heeger model, a topological semimetal phase with\nexceptional points is stabilized by the unique features of the GBZ. Namely,\nunder a change of a system parameter, the GBZ is deformed so that the system\nremains gapless. It is also shown that each energy band is divided into three\nregions, depending on the symmetry of the eigenstates, and the regions are\nseparated by the cusps and the exceptional points in the GBZ.",
        "positive": "Thermoelectrical manipulation of nano-magnets: We propose a device that can operate as a magneto-resistive switch or\noscillator. The device is based on a spin-thermo-electronic control of the\nexchange coupling of two strong ferromagnets through a weakly ferromagnetic\nspacer. We show that the local Joule heating due to a high concentration of\ncurrent in a magnetic point contact or a nanopillar can be used to reversibly\ndrive the weak ferromagnet through its Curie point and thereby\nexchange-decouple the strongly ferromagnetic layers, which have an antiparallel\nground state. Such a spin-thermionic parallel-to-antiparallel switching causes\nmagnetoresistance oscillations where the frequency can be controlled by proper\nbiasing from essentially DC to GHz."
    },
    {
        "anchor": "A Many-Body Theory of the Optical Conductivity of Excitons and Trions in\n  Two-Dimensional Materials: The optical spectra of two dimensional (2D) materials exhibit sharp\nabsorption peaks that are commonly identified with exciton and trions (or\ncharged excitons). In this paper, we show that excitons and trions in doped 2D\nmaterials can be described by two coupled Schrodinger-like equations - one\ntwo-body equation for excitons and another four-body equation for trions. In\nelectron doped 2D materials, a bound trion state is identified with a four-body\nbound state of an exciton and an excited conduction band electron-hole pair. In\ndoped 2D materials, the exciton and the trions states are the not the\neigenstates of the full Hamiltonian and their respective Schrodinger equations\nare coupled due to Coulomb interactions. The strength of this coupling\nincreases with the doping density. Solutions of these two coupled equations can\nquantitatively explain all the prominent features experimentally observed in\nthe optical absorption spectra of 2D materials including the observation of two\nprominent absorption peaks and the variation of their energy splittings and\nspectral shapes and strengths with the electron density. The optical\nconductivity obtained in our work satisfies the optical conductivity sum rule\nexactly. A superposition of exciton and trion states can be used to construct a\nsolution of the two coupled Schrodinger equations and this solution resembles\nthe variational exciton-polaron state, thereby establishing the relationship\nbetween our approach and Fermi polaron physics.",
        "positive": "Quantum theory of polariton weak lasing and polarization bifurcations: The quantum theory of polariton condensation in a trapped state reveals a\nsecond-order phase transition evidenced by spontaneous polarization parity\nbreaking in sub-spaces of fixed polariton occupation numbers. The emission\nspectra of polariton condensate demonstrate the coexistence of the\nsymmetry-conserving condensate state with the linear X polarization and the\nsymmetry-broken, elliptically polarized states in the vicinity of the\nthreshold. As a result, the oscillating linear second-order coherence\n$g^{(2)}_{xx}(t)$, with $g^{(2)}_{xx}(t)<1$ over some time intervals, is\nobtained. The spontaneous symmetry breaking is reflected in the second-order\ncross correlator of circular polarizations. The related build-up of\nelliptically-polarized weak lasing results also in non-monotonous dependence of\nthe circular second-order coherence on the excitation power and the interaction\nstrength."
    },
    {
        "anchor": "Random spin-orbit gates in the system of a Topological insulator and a\n  Quantum dot: The spin-dependent scattering process in a system of topological insulator\nand quantum dot is studied. The unitary scattering process is viewed as a gate\ntransformation applied to an initial state of two electrons. Due to the\nrandomness imposed through the impurities and alloying-induced effects of band\nparameters, the formalism of the random unitary gates is implemented. For\nquantifying entanglement in the system, we explored concurrence and\nensemble-averaged R\\'enyi entropy. We found that applied external magnetic\nfield leads to long-range entanglement on the distances much larger than the\nconfinement length. We showed that topological features of itinerant electrons\nsustain the formation of robust long-distance entanglement, which survives even\nin the presence of a strong disorder.",
        "positive": "Transport through a band insulator with Rashba spin-orbit coupling:\n  metal-insulator transition and spin-filtering effects: We calculate the current-voltage characteristic of a one-dimensional band\ninsulator with magnetic field and Rashba spin-orbit coupling which is connected\nto nonmagnetic leads. Without spin-orbit coupling we find a complete\nspin-filtering effect, meaning that the electric transport occurs in one spin\nchannel only. For a large magnetic field which closes the band gap, we show\nthat spin-orbit coupling leads to a transition from metallic to insulating\nbehavior. The oscillations of the different spin-components of the current with\nthe length of the transport channel are studied as well."
    },
    {
        "anchor": "Scaling Properties of Ge-SixGe1-x Core-Shell Nanowire Field Effect\n  Transistors: We demonstrate the fabrication of high-performance Ge-SixGe1-x core-shell\nnanowire field-effect transistors with highly doped source and drain, and\nsystematically investigate their scaling properties. Highly doped source and\ndrain regions are realized by low energy boron implantation, which enables\nefficient carrier injection with a contact resistance much lower than the\nnanowire resistance. We extract key device parameters, such as intrinsic\nchannel resistance, carrier mobility, effective channel length, and external\ncontact resistance, as well as benchmark the device switching speed and ON/OFF\ncurrent ratio.",
        "positive": "Quantum Anomalous Hall Effect in Flat Band Ferromagnet: We proposed a theory of quantum anomalous Hall effect in a flat-band\nferromagnet on a two-dimensional (2D) decorated lattice with spin-orbit\ncoupling. Free electrons on the lattice have dispersionless flat bands, and the\nground state is highly degenerate when each lattice site is occupied averagely\nby one electron, i.e., the system is at half filling. The on-site Coulomb\ninteraction can remove the degeneracy and give rise to the ferrimagnetism,\nwhich is the coexistence of the ferromagnetic and antiferromagnetic long-range\norders. On the other hand the spin-orbit coupling makes the band structure\ntopologically non-trivial, and produces the quantum spin Hall effect with a\npair of helical edge states around the system boundary. Based on the rigorous\nresults for the Hubbard model, we found that the Coulomb interaction can\nprovide an effective staggered potential and turn the quantum spin Hall phase\ninto a quantum anomalous Hall phase."
    },
    {
        "anchor": "Fully polarized states and decoherence: The aim of this review is to show how ``ferromagnetic'' states, that is,\nstates having a fully polarization, can produce intrinsic decoherence by\nunitary evolution. This effect can give an understanding of recent experiments\non mesoscopic devices as quantum point contacts showing the 0.7 conductance\nanomaly and the wide number of data about saturation of dephasing time observed\nat very low temperatures, as a fully polarized two dimensional electron gas.\nBut similar effects can be seen in different area of physics as for example the\nDicke model describing the interaction of two-level systems with a radiation\nmode. In this case one can show that decoherence is intrinsic and remove a\nSchr\\\"odinger cat state leaving a single coherent state, collapsing the wave\nfunction in the thermodynamic limit. So, saturation of dephasing time at low\ntemperatures in mesoscopic devices can be understood by a fully polarized two\ndimensional electron gas that, by an exchange model, can be reduced to a\ngeneralized form of the Dicke Hamiltonian and where the quasiparticles are spin\nexcitations interacting with magnons. In this way, one can see that several\nexperiments on nanowires and quantum dots can be satisfactorily explained. The\nexistence of intrinsic decoherence in the thermodynamic limit could have deep\nimplications in fundamental problems like quantum measurement and\nirreversibility. Recent experiments with cavities with a large number of\nphotons and with nuclear magnetic resonance in organic molecular crystals give\na first strong support to this view.",
        "positive": "Mode coupling and evolution in broken-symmetry plasmas: The control of nonlinear processes and possible transitions to chaos in\nsystems of interacting particles is a fundamental physical problem. We propose\na new nonuniform solid-state plasma system, produced by the optical injection\nof current in two-dimensional semiconductor structures, where this control can\nbe achieved. Due to an injected current, the system symmetry is initially\nbroken. The subsequent nonequilibrium dynamics is governed by the spatially\nvarying long-range Coulomb forces and electron-hole collisions. As a result,\ninhomogeneities in the charge and velocity distributions should develop\nrapidly, and lead to previously unexpected experimental consequences. We\nsuggest that the system eventually evolves into a behavior similar to chaos."
    },
    {
        "anchor": "Ultrafast Emission and Detection of a Single-Electron Gaussian Wave\n  Packet: A Theoretical Study: Generating and detecting a prescribed single-electron state is an important\nstep towards solid-state fermion optics. We propose how to generate an electron\nin a Gaussian state, using a quantum-dot pump with gigahertz operation and\nrealistic parameters. With the help of a strong magnetic field, the electron\noccupies a coherent state in the pump, insensitive to the details of\nnonadiabatic evolution. The state changes during the emission from the pump,\ngoverned by competition between the Landauer-Buttiker traversal time and the\npassage time. When the former is much shorter than the latter, the emitted\nstate is a Gaussian wave packet. The Gaussian packet can be identified by using\na dynamical potential barrier, with a resolution reaching the Heisenberg\nminimal uncertainty $\\hbar/2$.",
        "positive": "Nonlinear elasticity of monolayer graphene: By combining continuum elasticity theory and tight-binding atomistic\nsimulations, we work out the constitutive nonlinear stress-strain relation for\ngraphene stretching elasticity and we calculate all the corresponding nonlinear\nelastic moduli. Present results represent a robust picture on elastic behavior\nof one-atom thick carbon sheets and provide the proper interpretation of recent\nexperiments. In particular, we discuss the physical meaning of the effective\nnonlinear elastic modulus there introduced and we predict its value in good\nagreement with available data. Finally, a hyperelastic softening behavior is\nobserved and discussed, so determining the failure properties of graphene."
    },
    {
        "anchor": "Low energy exciton states in a nanoscopic semiconducting ring: We consider an effective mass model for an electron-hole pair in a simplified\nconfinement potential, which is applicable to both a nanoscopic self-assembled\nsemiconducting InAs ring and a quantum dot. The linear optical susceptibility,\nproportional to the absorption intensity of near-infrared transmission, is\ncalculated as a function of the ring radius $% R_0$. Compared with the\nproperties of the quantum dot corresponding to the model with a very small\nradius $R_0$, our results are in qualitative agreement with the recent\nexperimental measurements by Pettersson {\\it et al}.",
        "positive": "Skyrmion-mediated Nonvolatile Ternary Memory: Multistate memory systems have the ability to store and process more data in\nthe same physical space as binary memory systems, making them a potential\nalternative to existing binary memory systems. In the past, it has been\ndemonstrated that voltage-controlled magnetic anisotropy (VCMA) based writing\nis highly energy-efficient compared to other writing methods used in\nnon-volatile nano-magnetic binary memory systems. In this study, we introduce a\nnew, VCMA-based and skyrmion-mediated non-volatile ternary memory system using\na perpendicular magnetic tunnel junction (p-MTJ) in the presence of room\ntemperature thermal perturbation. We have also shown that ternary states {-1,\n0, +1} can be implemented with three magnetoresistance values obtained from a\np-MTJ corresponding to ferromagnetic up, down, and skyrmion state, with 99%\nswitching probability in the presence of room temperature thermal noise in an\nenergy-efficient way, requiring ~3 fJ energy on an average for each switching\noperation. Additionally, we show that our proposed ternary memory demonstrates\nan improvement in area and energy by at least 2X and ~60X respectively,\ncompared to state-of-the-art spin-transfer torque (STT)-based non-volatile\nmagnetic multistate memories. Furthermore, these three states can be\npotentially utilized for energy-efficient, high-density in-memory quantized\ndeep neural network implementation."
    },
    {
        "anchor": "Exciton Transport in a Bilayer Quantum Hall Superfluid: Bilayer quantum Hall systems at \\nu =1 support an excitonic ground state. In\naddition to the usual charged quasiparticles, this system possesses a\ncondensate degree of freedom: exciton transport. Detection of this neutral\ntransport mode is facilitated by the use of the Corbino multiply-connected\ngeometry in which charge transport is suppressed. We here summarize our recent\nexperiments on Corbino devices which directly demonstrate exciton transport\nacross the bulk of the incompressible \\nu =1 quantum Hall state.",
        "positive": "Quantum-ring spin interference device tuned by quantum point contacts: We introduce a spin-interference device that comprises a quantum ring (QR)\nwith three embedded quantum point contacts (QPCs) and study theoretically its\nspin transport properties in the presence of Rashba spin-orbit interaction. Two\nof the QPCs conform the lead-to-ring junctions while a third one is placed\nsymmetrically in the upper arm of the QR. Using an appropriate scattering model\nfor the QPCs and the $\\mathbb{S}$-matrix scattering approach, we analyze the\nrole of the QPCs on the Aharonov-Bohm (AB) and Aharonov-Casher (AC) conductance\noscillations of the QR-device. Exact formulas are obtained for the\nspin-resolved conductances of the QR-device as a function of the confinement of\nthe QPCs and the AB/AC phases. Conditions for the appearance of resonances and\nanti-resonances in the spin-conductance are derived and discussed. We predict\nvery distinctive variations of the QR-conductance oscillations not seen in\nprevious QR proposals. In particular we find that the interference pattern in\nthe QR can be manipulated to a large extend by varying electrically the\nlead-to-ring topological parameters. The latter can be used to modulate the AB\nand AC phases by applying gate voltage only. We have shown also that the\nconductance oscillations exhibits a crossover to well-defined resonances as the\nlateral QPC confinement strength is increased, mapping the eigenenergies of the\nQR. In addition, unique features of the conductance arises by varying the\naperture of the upper-arm QPC and the Rashba spin-orbit coupling. Our results\nmay be of relevance for promising spin-orbitonics devices based in quantum\ninterference mechanisms."
    },
    {
        "anchor": "Theory of the Interfacial Dzyaloshinskii-Moriya Interaction in Rashba\n  Antiferromagnets: In antiferromagnetic (AFM) thin films, broken inversion symmetry or coupling\nto adjacent heavy metals can induce Dzyaloshinskii-Moriya (DM) interactions.\nKnowledge of the DM parameters is essential for understanding and designing\nexotic spin structures, such as hedgehog Skyrmions and chiral N\\'eel walls,\nwhich are attractive for use in novel information storage technologies. We\nintroduce a framework for computing the DM interaction in two-dimensional\nRashba antiferromagnets. Unlike in Rashba ferromagnets, the DM interaction is\nnot suppressed even at low temperatures. The material parameters control both\nthe strength and the sign of the interfacial DM interaction. Our results\nsuggest a route toward controlling the DM interaction in AFM materials by means\nof doping and electric fields.",
        "positive": "Quantum anomalous Hall effect and related topological electronic states: Over a long period of exploration, the successful observation of quantized\nversion of anomalous Hall effect (AHE) in thin film of magnetically-doped\ntopological insulator completed a quantum Hall trio---quantum Hall effect\n(QHE), quantum spin Hall effect (QSHE), and quantum anomalous Hall effect\n(QAHE). On the theoretical front, it was understood that intrinsic AHE is\nrelated to Berry curvature and U(1) gauge field in momentum space. This\nunderstanding established connection between the QAHE and the topological\nproperties of electronic structures characterized by the Chern number. With the\ntime reversal symmetry broken by magnetization, a QAHE system carries\ndissipationless charge current at edges, similar to the QHE where an external\nmagnetic field is necessary. The QAHE and corresponding Chern insulators are\nalso closely related to other topological electronic states, such as\ntopological insulators and topological semimetals, which have been extensively\nstudied recently and have been known to exist in various compounds.\nFirst-principles electronic structure calculations play important roles not\nonly for the understanding of fundamental physics in this field, but also\ntowards the prediction and realization of realistic compounds. In this article,\na theoretical review on the Berry phase mechanism and related topological\nelectronic states in terms of various topological invariants will be given with\nfocus on the QAHE and Chern insulators. We will introduce the Wilson loop\nmethod and the band inversion mechanism for the selection and design of\ntopological materials, and discuss the predictive power of first-principles\ncalculations. Finally, remaining issues, challenges and possible applications\nfor future investigations in the field will be addressed."
    },
    {
        "anchor": "Gate-tunable electron interaction in high-\u03ba dielectric films: The two-dimensional (2D) logarithmic character of Coulomb interaction between\ncharges and the resulting logarithmic confinement is a remarkable inherent\nproperty of high dielectric constant (high-$\\kappa$) thin films with far\nreaching implications. Most and foremost, this is the charge\nBerezinskii-Kosterlitz-Thouless transition with the notable manifestation,\nlow-temperature superinsulating topological phase. Here we show that the range\nof the confinement can be tuned by the external gate electrode and unravel a\nvariety of electrostatic interactions in high-$\\kappa$ films. We find that by\nreducing the distance from the gate to the film, we decrease the spatial range\nof the 2D long-range logarithmic interaction, changing it to predominantly\ndipolar or even to exponential one at lateral distances exceeding the dimension\nof the film-gate separation. Our findings offer a unique laboratory for the\nin-depth study of topological phase transitions and related phenomena that\nrange from criticality of quantum metal- and superconductor-insulator\ntransitions to the effects of charge-trapping and Coulomb scalability in memory\nnanodevices.",
        "positive": "Nonlinear light absorption in colloidal CdSe/CdS nanoplatelets: We investigated the nonlinear optical properties of CdSe/CdS nanoplatelets in\nthe vicinity of heavy hole and light hole exciton resonances. The two color\npump-probe technique was applied. The first intense pulse created\nnon-equilibrium exciton population, which was detected as a decrease of probe\nlight absorption. We observed intense scattering of excitons between heavy- and\nlight-hole excitonic states. We also studied experimentally saturation of\nabsorption in nanoplatelets. Theoretical description of these phenomena allowed\nus to determine parameters of exciton dynamics in nanoplatelets."
    },
    {
        "anchor": "Quantification of interfacial spin-charge conversion in metal/insulator\n  hybrid structures by generalized boundary conditions: We present and verify experimentally a universal theoretical framework for\nthe description of spin-charge interconversion in non-magnetic metal/insulator\nstructures with interfacial spin-orbit coupling (ISOC). Our formulation is\nbased on drift-diffusion equations supplemented with generalized boundary\nconditions. The latter encode the effects of ISOC and relate the electronic\ntransport in such systems to spin loss and spin-charge interconversion at the\ninterface, which are parameterized, respectively, by $G_{\\parallel/\\perp}$ and\n$\\sigma_{\\rm{sc/cs}}$. We demonstrate that the conversion efficiency depends\nsolely on these interfacial parameters. We apply our formalism to two typical\nspintronic devices that exploit ISOC: a lateral spin valve and a multilayer\nHall bar, for which we calculate the non-local resistance and the spin Hall\nmagnetoresistance, respectively. Finally, we perform measurements on these two\ndevices with a BiO$_x$/Cu interface and verify that transport properties\nrelated to the ISOC are quantified by the same set of interfacial parameters.",
        "positive": "Bulk Nanocrystalline Thermoelectrics Based on Bi-Sb-Te Solid Solution: A nanopowder from p-Bi-Sb-Te with particles ~ 10 nm were fabricated by the\nball milling using different technological modes. Cold and hot pressing at\ndifferent conditions and also SPS process were used for consolidation of the\npowder into a bulk nanostructure and nanocomposites. The main factors allowing\nslowing-down of the growth of nanograins as a result of recrystallization are\nthe reduction of the temperature and of the duration of the pressing, the\nincrease of the pressure, as well as addition of small value additives (like\nMoS2, thermally expanded graphite or fullerenes). It was reached the\nthermoelectric figure of merit ZT=1.22 (at 360 K) in the bulk nanostructure\nBi0,4Sb1,6Te3 fabricated by SPS method. Some mechanisms of the improvement of\nthe thermoelectric efficiency in bulk nanocrystalline semiconductors based on\nBixSb2-xTe3 are studied theoretically. The reduction of nanograin size can lead\nto improvement of the thermoelectric figure of merit. The theoretical\ndependence of the electric and heat conductivities and the thermoelectric power\nas the function of nanograins size in BixSb2-xTe3 bulk nanostructure are quite\naccurately correlates with the experimental data."
    },
    {
        "anchor": "Weak-localization and rectification current in non-diffusive quantum\n  wires: We show that electron transport in disordered quantum wires can be described\nby a modified Cooperon equation, which coincides in form with the Dirac\nequation for the massive fermions in a 1+1 dimensional system. In this new\nformalism, we calculate the DC electric current induced by electromagnetic\nfields in quasi-one-dimensional rings. This current changes sign, from\ndiamagnetic to paramagnetic, depending on the amplitude and frequency of the\ntime-dependent external electromagnetic field.",
        "positive": "Impact of structural defects on the performance of graphene\n  plasmon-based molecular sensors: Graphene-based plasmonic devices are regarded to be suitable for a plethora\nof applications, ranging from mid-infrared to terahertz frequencies. In this\nregard, among the peculiarities associated with graphene, it is well known that\nplasmons are tunable and tend to show stronger confinement as well as a longer\nlifetime than in the noble-metal counterpart. However, due to the\ntwo-dimensional specificity of graphene, the presence of defects might induce\nstronger effects than in bulky noble metals. Here, we theoretically investigate\nthe impact of structural defects hosted by graphene on selected figures of\nmerit associated to localized plasmons, which are of key technological\nimportance for plasmon-based molecular sensing. By considering an optimized\ngraphene nanostructure, we provide a comparative analysis intended to shed\nlight on the impact of the type of defect on graphene localized plasmons, that\nregards distinct types of defects commonly arising from fabrication procedures\nor exposure to radiation. This understanding will help industry and academia in\nbetter identifying the most suitable applications for graphene-based molecular\nsensing."
    },
    {
        "anchor": "Supersymmetry in the Majorana Cooper-Pair Box: Over the years, supersymmetric quantum mechanics has evolved from a toy model\nof high energy physics to a field of its own. Although various examples of\nsupersymmetric quantum mechanics have been found, systems that have a natural\nrealization are scarce. Here, we show that the extension of the conventional\nCooper-pair box by a 4pi-periodic Majorana-Josephson coupling realizes\nsupersymmetry for certain values of the ratio between the conventional\nJosephson and the Majorana- Josephson coupling strength. The supersymmetry we\nfind is a \"hidden\" minimally bosonized supersymmetry that provides a\nnon-trivial generalization of the supersymmetry of the free particle and relies\ncrucially on the presence of an anomalous Josephson junction in the system. We\nshow that the resulting degeneracy of the energy levels can be probed directly\nin a tunneling experiment and discuss the various transport signatures. An\nobservation of the predicted level degeneracy would provide clear evidence for\nthe presence of the anomalous Josephson coupling.",
        "positive": "Level statistics of quantum dots coupled to reservoirs: We study the effect of electron tunneling on the level statistics of quantum\ndots. While the coupling between individual levels and the electron reservoir\nleads predominantly to the expected level broadening, the indirect coupling of\nadjacent levels via the reservoir results in a new asymptotic level statistics\nand broadening. These features, which are attributed to renormalized spectral\nweights rather than renormalized eigenvalues of the Hamiltonian, are observable\nin the asymptotic frequency dependence in an absorption experiment."
    },
    {
        "anchor": "Quantum tunneling of magnetization in lanthanide single-molecule\n  magnets, bis(phthalocyaninato)terbium and bis(phthalocyaninato)-dysprosium\n  anions: Magnetization versus field measurements were performed on single crystals of\n[(Pc)2TbIII0.02YIII0.98]^TBA+ and [(Pc)2DyIII0.02YIII0.98]^TBA+ (Pc:\nphthalocyaninato, TBA: tetrabutylammonium) at 0.04 K. The [(Pc)2TbIII] complex,\nthe first lanthanide single-molecule magnet, exhibited clear staircase-like\nstructures, which are assigned to resonant quantum tunneling between entangled\nstates of the electron and nuclear spin systems.",
        "positive": "Spatial distribution of dynamically polarized nuclear spins in electron\n  spin domains in the $\u03bd= 2/3$ fractional quantum Hall state studied by\n  nuclear electric resonance: Nuclear electric resonance (NER) is based on nuclear magnetic resonance\nmediated by spatial oscillations of electron spin domains excited by a radio\nfrequency (RF) electric field, and it allows us to investigate the spatial\ndistribution of the nuclear spin polarization around domain walls (DWs). Here,\nNER measurements were made of the dynamic nuclear spin polarization (DNP) at\nthe spin phase transition of the fractional quantum Hall state at a Landau\nlevel filling factor of $\\nu=2/3$. From the RF pulse power and pulse duration\ndependence of the NER spectrum, we show that the DNP occurs only within $\\sim\n100$ nm around DWs, and that it does not occur in DWs. We also show that DWs\nare pinned by the hyperfine field from polarized nuclear spins."
    },
    {
        "anchor": "Bulk and edge correlations in the compressible half-filled quantum Hall\n  state: We study bulk and edge correlations in the compressible half-filled state,\nusing a modified version of the plasma analogy. The corresponding plasma has\nanomalously weak screening properties, and as a consequence we find that the\ncorrelations along the edge do not decay algebraically as in the Laughlin\n(incompressible) case, while the bulk correlations decay in the same way. The\nresults suggest that due to the strong coupling between charged modes on the\nedge and the neutral Fermions in the bulk, reflected by the weak screening in\nthe plasma analogue, the (attractive) correlation hole is not well defined on\nthe edge. Hence, the system there can be modeled as a free Fermi gas of {\\em\nelectrons} (with an appropriate boundary condition). We finally comment on a\npossible scenario, in which the Laughlin-like dynamical edge correlations may\nnevertheless be realized.",
        "positive": "Spatial Ordering of Defects and Conductivity of Functionalized Graphene: Recently, it was predicted that an RKKY-type interaction between adatoms in\ngraphene can drive an ordering transition to a state with broken sublattice\nsymmetry (arXiv:1004.3678). In this state, due to Bragg scattering of electron\nwaves on the sublattice modulation, a gap opens up at the Dirac point (DP).\nHere we investigate the effect of ordering on the transport properties, finding\nthat upon transition from disordered state to an ordered state the conductivity\nis increased (reduced) at energies away (near) DP. This behavior can be\nunderstood as a result of coherent Bragg scattering in the ordered state. The\nconductivity change can serve as a direct signature of adatom ordering."
    },
    {
        "anchor": "Resonant tunneling-based spin ratchets: We outline a generic ratchet mechanism for creating directed spin-polarized\ncurrents in ac-driven double well or double dot structures by employing\nresonant spin transfer through the system engineered by local external magnetic\nfields. We show its applicability to semiconductor nanostructures by\nconsidering coherent transport through two coupled lateral quantum dots, where\nthe energy levels of the two dots exhibit opposite Zeeman spin splitting. We\nperform numerical quantum mechanical calculations for the I-V characteristics\nof this system in the nonlinear regime, which requires a self-consistent\ntreatment of the charge redistribution due to the applied finite bias. We show\nthat this setting enables nonzero averaged net spin currents in the absence of\nnet charge transport.",
        "positive": "Fragility of multi-junction flux qubits against quasiparticle tunneling: We study decoherence in superconducting qubits due to quasiparticle tunneling\nwhich is enhanced by two known deviations from the equilibrium BCS theory. The\nfirst process corresponds to tunneling of an already existing quasiparticle\nacross the junction. The quasiparticle density is increased, e.g., because of\nan effective quasiparticle doping of the system. The second process is\nquasiparticle tunneling by breaking of a Cooper pair. This can happen at\ntypical energies of superconducting qubits if there is an extended\nquasiparticle density inside the gap. We calculate the induced energy decay and\npure dephasing rates in typical qubit designs. Assuming the lowest reported\nvalue of the non-equilibrium quasiparticle density in Aluminum, we find for the\npersistent-current flux qubit decay times of the order of recent measurements.\nUsing the typical sub-gap density of states in Niobium we also reproduce\nobserved decay times in the corresponding Niobium flux qubits."
    },
    {
        "anchor": "Time-dependent current into and through multilevel parallel quantum dots\n  in a photon cavity: We analyze theoretically the charging current into, and the transport current\nthrough, a nanoscale two-dimensional electron system with two parallel quantum\ndots embedded in a short wire placed in a photon cavity. A plunger gate is used\nto place specific many-body states of the interacting system in the bias window\ndefined by the external leads. We show how the transport phenomena active in\nthe many-level complex central system strongly depend on the gate voltage. We\nidentify a resonant transport through the central system as the two spin\ncomponents of the one-electron ground state are in the bias window. This\nresonant transport through the lowest energy electron states seems to a large\nextent independent of the detuned photon field when judged from the transport\ncurrent. This could be expected in the small bias regime, but an observation of\nthe occupancy of the states of the system reveals that this picture is not\nentirely true. The current does not reflect slower photon-active internal\ntransitions bringing the system into the steady state. The number of initially\npresent photons determines when the system reaches the real steady state. With\ntwo-electron states in the bias window we observe a more complex situation with\nintermediate radiative and nonradiative relaxation channels leading to a steady\nstate with a weak nonresonant current caused by inelastic tunneling through the\ntwo-electron ground state of the system. The presence of the radiative channels\nmakes this phenomena dependent on the number of photons initially in the\ncavity.",
        "positive": "Geometric Response and Disclination-Induced Skin Effects in\n  Non-Hermitian Systems: We study the geometric response of three-dimensional non-Hermitian\ncrystalline systems with nontrivial point-gap topology. For systems with\nfourfold rotation symmetry, we show that in the presence of disclination lines\nwith a total Frank angle which is an integer multiple of $2\\pi$, there can be\nnontrivial one-dimensional point-gap topology along the direction of the\ndisclination lines. This results in disclination-induced non-Hermitian skin\neffects. By doubling a non-Hermitian Hamiltonian to a Hermitian\nthree-dimensional chiral topological insulator, we show that the\ndisclination-induced skin modes are zero modes of the effective surface Dirac\nfermion(s) in the presence of a pseudomagnetic flux induced by disclinations.\nFurthermore, we find that our results have a field theoretic description, and\nthe corresponding geometric response actions (e.g., the Euclidean Wen-Zee\naction) enrich the topological field theory of non-Hermitian systems."
    },
    {
        "anchor": "On-chip SQUID measurements in the presence of high magnetic fields: We report a low temperature measurement technique and magnetization data of a\nquantum molecular spin, by implementing an on-chip SQUID technique. This\ntechnique enables the SQUID magnetometery in high magnetic fields, up to 7\nTesla. The main challenges and the calibration process are detailed. The\nmeasurement protocol is used to observe quantum tunneling jumps of the S=10\nmolecular magnet, Mn12-tBuAc. The effect of transverse field on the tunneling\nsplitting for this molecular system is addressed as well.",
        "positive": "3D ferroelectric phase field simulations of polycrystalline multi-phase\n  hafnia and zirconia based ultra-thin films: HfO$_2$- and ZrO$_2$-based ferroelectric thin films have emerged as promising\ncandidates for the gate oxides of next generation electronic devices. Recent\nwork has experimentally demonstrated that a tetragonal/orthorhombic (t/o-)\nphase mixture with partially in-plane polarization can lead to negative\ncapacitance (NC) stabilization. However, there is a discrepancy between\nexperiments and the theoretical understanding of domain formation and domain\nwall motion in these multi-phase, polycrystalline materials. Furthermore, the\neffect of anisotropic domain wall coupling on NC has not been studied so far.\nHere we apply 3D phase field simulations of HfO$_2$- and ZrO$_2$-based\nmixed-phase ultra-thin films on silicon to understand the necessary and\nbeneficial conditions for NC stabilization. We find that smaller ferroelectric\ngrains and a larger angle of the polar axis with respect to the out-of-plane\ndirection enhances the NC effect. Furthermore, we show that theoretically\npredicted negative domain wall coupling even along only one axis prevents NC\nstabilization. Therefore, we conclude that topological domain walls play a\ncritical role in experimentally observed NC phenomena in HfO$_2$- and\nZrO$_2$-based ferroelectrics."
    },
    {
        "anchor": "Ab initio calculation of the $G$ peak intensity of graphene: Combined\n  study of the laser and Fermi energy dependence and importance of quantum\n  interference effects: We present the results of a diagrammatic, fully ab initio calculation of the\n$G$ peak intensity of graphene. The flexibility and generality of our approach\nenables us to go beyond the previous analytical calculations in the low-energy\nregime. We study the laser and Fermi energy dependence of the $G$ peak\nintensity and analyze the contributions from resonant and non-resonant\nelectronic transitions. In particular, we explicitly demonstrate the importance\nof quantum interference and non-resonant states for the $G$ peak process. Our\nmethod of analysis and computational concept is completely general and can\neasily be applied to study other materials as well.",
        "positive": "Proximity nanovalve with large phase-tunable thermal conductance: We propose a phase-controlled heat-flux quantum valve based on the proximity\neffect driven by a superconducting quantum interference proximity transistor\n(SQUIPT). Its operation relies on the phase-dependent quasiparticle density of\nstates in the Josephson weak-link of the SQUIPT which controls thermal\ntransport across the device. In a realistic Al/Cu-based setup the structure can\nprovide efficient control of thermal current inducing temperature swings\nexceeding $\\sim100$~mK, and flux-to-temperature transfer coefficients up to\n$\\sim 500$~mK/$\\Phi_0$ below 100~mK. The nanovalve performances improve by\nlowering the bath temperature, making the proposed structure a promising\nbuilding-block for the implementation of coherent caloritronic devices\noperating below 1~K."
    },
    {
        "anchor": "Spin current pumped by resonant skyrmion: Spin pumping is a widely recognized method to generate the spin current in\nthe spintronics, which is acknowledged as a fundamentally dynamic process\nequivalent to the spin-transfer torque. In this work, we theoretically verify\nthat the oscillating spin current can be pumped from the microwave-motivated\nbreathing skyrmion. The skyrmion spin pumping can be excited by a relatively\nlow frequency compared with the ferromagnetic resonance (FMR) and the current\ndensity is larger than the ordinary FMR spin pumping. Based on the skyrmion\nspin pumping, we build a high reading-speed racetrack memory model whose\nreading speed is an order of magnitude higher than the SOT (spin-orbit torque)\n/STT (spin-transfer torque) skyrmion racetrack. Our work explored the spin\npumping phenomenon in the skyrmion, and it may contribute to the applications\nof the skyrmion-based device.",
        "positive": "Nonlinear optical response and exciton dephasing in quantum dots: The full time-dependent four-wave mixing polarization in quantum dots is\nmicroscopically calculated, taking into account acoustic phonon-assisted\ntransitions between different exciton states of the dot. It is shown that quite\ndifferent dephasing times of higher exciton states in pancake anisotropic\nInGaAs quantum dots are responsible for the experimentally observed [1]\ndouble-exponential decay in the photon echo signal."
    },
    {
        "anchor": "Inherently high valley polarizations of momentum-forbidden dark excitons\n  in transition-metal dichalcogenide monolayers: High degree of valley polarization of optically active excitons in\ntransition-metal dichalcogenide monolayers (TMD-MLs) is vital in valley-based\nphotonic applications but known to be likely spoiled by the intrinsic\nelectron-hole exchange interactions. In this study, we present a theoretical\ninvestigation of the valley and optical properties of finite-momentum dark\nexcitons in WSe$_2$-MLs by solving the density-functional-theory(DFT)-based\nBethe-Salpeter equation (BSE) under the guidance of symmetry analysis. %We\nreveal that, in general, finite-momentum excitons are actually well immune from\nthe exchange-induced valley depolarization, except for those with specific\nexciton momenta coincident with the $3\\sigma_v$ and $3C_2'$ symmetries in the\n$D_{3h}$ point group of TMD-MLs. We reveal that, unlike the bright exciton\ninevitably subjected to electron-hole exchange interaction, inter-valley\nfinite-momentum dark excitons in WSe$_2$-MLs are well immune from the\nexchange-induced valley depolarization and inherently highly valley-polarized\nunder the enforcement of the crystal symmetries. More importantly, the superior\nvalley polarizations of the inter-valley dark excitons in WSe$_2$-MLs are shown\nalmost fully transferable to the optical polarization in the phonon-assisted\nphoto-luminescences because of the native suppression of exchange-induced\ndepolarization in the second-order optical processes. The analysis of\nphonon-assisted photo-luminescences accounts for the recently observed\nbrightness, high degree of optical polarization and long lifetime of the\ninter-valley dark exciton states in tungsten-based TMD-MLs.",
        "positive": "Asymmetric arms maximise visibility in hot-electron interferometers: We consider theoretically an electronic Mach-Zehnder interferometer\nconstructed from quantum Hall edge channels and quantum point contacts, fed\nwith single electrons from a dynamic quantum dot source. By considering the\nenergy dependence of the edge-channel guide centres, we give an account of the\nphase averaging in this set up that is particularly relevant for the short,\nhigh-energy wavepackets injected by this type of electron source. We present\nboth analytic and numerical results for the energy-dependent arrival time\ndistributions of the electrons and also give an analysis of the delay times\nassociated with the quantum point contacts and their effects on the\ninterference patterns. A key finding is that, contrary to expectation, maximum\nvisibility requires the interferometer arms to be different in length, with an\noffset of up to a micron for typical parameters. By designing interferometers\nthat incorporate this asymmetry in their geometry, phase-averaging effects can\nbe overcome such that visibility is only limited by other incoherent\nmechanisms."
    },
    {
        "anchor": "Supercapacitors composed of graphene and boron nitride layers: A\n  first-principles study: We propose a model for nanoscale supercapacitor consisting of two-dimensional\ninsulating BN layers placed between two commensurate and metallic graphene\nlayers. First-principles Density Functional calculations of structure optimized\ntotal energy and self-consistent field potential performed on these nanoscale\ncapacitors for different levels of charging and different number of BN layers\nmark the values of capacitance per unit mass, which are larger than those\nmeasured values for the supercapacitors made from other carbon based materials.\nOur theoretical study also compares results obtained for the present nanoscale\ncapacitor with those of classical Helmholtz model and reveals crucial\ndifferences. Our model allows the fabrication of series/parallel mixed\ncombinations consisting of epitaxially grown, sequential and multiple\ngraphene/BN sheets.",
        "positive": "Tailoring magnetic interactions in atomic bilayers of Rh and Fe on\n  Re(0001): Using density functional theory, we investigate the interplay between the\nstacking order and sequence of bilayers composed of an Fe and a Rh layer on the\nRe(0001) and their magnetic properties. We find that fcc/ffc stacked bilayers\nare energetically very unfavorable, while all other combinations of hcp and fcc\nstacking are energetically close. The magnetic interactions are evaluated by\nmapping the DFT total energies onto a spin model, which contains Heisenberg\nexchange, Dzyaloshinskii-Moriya interaction, the magnetocrystalline anisotropy\nenergy, and higher-order exchange interactions. We find that the stacking\nsequence of the bilayer significantly modifies the magnetic interactions. As a\nresult, we find a DMI driven cycloidal spin spiral ground state with a period\nof 11~nm for hcp-Fe/hcp-Rh. For fcc-Fe/hcp-Rh and hcp-Fe/fcc-Rh, we obtain a\nferromagnetic ground state. The spin spiral energy dispersion of hcp-Fe/hcp-Rh\nincluding spin-orbit coupling suggests that isolated skyrmions can be\nstabilized in the field-polarized ferromagnetic background at external magnetic\nfields. If the Fe layer is sandwiched between the Rh overlayer and the Re(0001)\nsubstrate, there is a competition between the ferromagnetic coupling preferred\nby the Rh-Fe hybridization and the antiferromagnetic coupling induced by the\nFe-Re hybridization. Due to the Fe/Re interface the DMI can become very large.\nFor fcc-Rh/hcp-Fe, we obtain a cycloidal spin spiral with a period of 1.7~nm\nwhich is induced by frustration of exchange interactions and further stabilized\nby the DMI. For hcp-Rh/hcp-Fe, we find a DMI driven cycloidal spin spiral with\na period of 4~nm and locally nearly antiparallel magnetic moments due to\nantiferromagnetic nearest-neighbor exchange. The higher-order exchange\nconstants can be significant in the considered films, however, they do not\nstabilize multi-$Q$ states."
    },
    {
        "anchor": "Majorana Kramers pairs in Rashba double nanowires with interactions and\n  disorder: We analyze the effects of electron-electron interactions and disorder on a\nRashba double-nanowire setup coupled to an s-wave superconductor, which has\nbeen recently proposed as a versatile platform to generate Kramers pairs of\nMajorana bound states in the absence of magnetic fields. We identify the regime\nof parameters for which these Kramers pairs are stable against interaction and\ndisorder effects. We use bosonization, perturbative renormalization group, and\nreplica techniques to derive the flow equations for various parameters of the\nmodel and evaluate the corresponding phase diagram with topological and\ndisorder-dominated phases. We confirm aforementioned results by considering a\nmore microscopic approach which starts from the tunneling Hamiltonian between\nthe three-dimensional s-wave superconductor and the nanowires. We find again\nthat the interaction drives the system into the topological phase and, as the\nstrength of the source term coming from the tunneling Hamiltonian increases,\nstrong electron-electron interactions are required to reach the topological\nphase.",
        "positive": "Chiral magnetoresistance in Pt/Co/Pt zigzag wires: The Rashba effect leads to a chiral precession of the spins of moving\nelectrons while the Dzyaloshinskii-Moriya interaction (DMI) generates\npreference towards a chiral profile of local spins. We predict that the\nexchange interaction between these two spin systems results in a 'chiral'\nmagnetoresistance depending on the chirality of the local spin texture. We\nobserve this magnetoresistance by measuring the domain wall (DW) resistance in\na uniquely designed Pt/Co/Pt zigzag wire, and by changing the chirality of the\nDW with applying an in-plane magnetic field. A chirality-dependent DW\nresistance is found, and a quantitative analysis shows a good agreement with a\ntheory based on the Rashba model. Moreover, the DW resistance measurement\nallows us to independently determine the strength of the Rashba effect and the\nDMI simultaneously, and the result implies a possible correlation between the\nRashba effect, the DMI, and the symmetric Heisenberg exchange."
    },
    {
        "anchor": "Negative terahertz conductivity in remotely doped graphene bilayer\n  heterostructures: Injection or optical generation of electrons and holes in graphene bilayers\n(GBLs) can result in the interband population inversion enabling the terahertz\n(THz) radiation lasing. The intraband radiative processes compete with the\ninterband transitions. We demonstrate that remote doping enhances the indirect\ninterband generation of photons in the proposed GBL heterostructures. Therefore\nsuch remote doping helps surpassing the intraband (Drude) absorption and\nresults in large absolute values of the negative dynamic THz conductivity in a\nwide range of frequencies at elevated (including room) temperatures. The\nremotely doped GBL heterostructure THz lasers are expected to achieve higher\nTHz gain compared to previously proposed GBL-based THz lasers.",
        "positive": "Spin-dependent resistivity at transitions between integer quantum Hall\n  states: The longitudinal resistivity at transitions between integer quantum Hall\nstates in two-dimensional electrons confined to AlAs quantum wells is found to\ndepend on the spin orientation of the partially-filled Landau level in which\nthe Fermi energy resides. The resistivity can be enhanced by an order of\nmagnitude as the spin orientation of this energy level is aligned with the\nmajority spin. We discuss possible causes and suggest a new explanation for\nspike-like features observed at the edges of quantum Hall minima near Landau\nlevel crossings."
    },
    {
        "anchor": "Spectroscopic visualization of flat bands in magic-angle twisted\n  monolayer-bilayer graphene: localization-delocalization coexisting electronic\n  states: Recent transport studies have demonstrated the great potential of twisted\nmonolayer-bilayer graphene (tMBG) as a new platform to host moir\\'e flat bands\nwith a higher tunability than twisted bilayer graphene (tBG). However, a direct\nvisualization of the flat bands in tMBG and its comparison with the ones in tBG\nremain unexplored. Here, via fabricating on a single sample with exactly the\nsame twist angle of ~1.13{\\deg}, we present a direct comparative study between\ntMBG and tBG using scanning tunneling microscopy/spectroscopy. We observe a\nsharp density of states peak near the Fermi energy in tunneling spectroscopy,\nconfirming unambiguously the existence of flat electronic bands in tMBG. The\nbandwidth of this flat-band peak is found to be slightly narrower than that of\nthe tBG, validating previous theoretical predictions. Remarkably, by measuring\nspatially resolved spectroscopy, combined with continuum model calculation, we\nshow that the flat-band states in tMBG exhibit a unique layer-resolved\nlocalization-delocalization coexisting feature, which offers an unprecedented\npossibility to utilize their cooperation on exploring novel correlation\nphenomena. Our work provides important microscopic insight of flat-band states\nfor better understanding the emergent physics in graphene moir\\'e systems.",
        "positive": "Universal chiral-triggered magnetization switching in confined nanodots: Spin orbit interactions are rapidly emerging as the key for enabling\nefficient current-controlled spintronic devices. Much work has focused on the\nrole of spin-orbit coupling at heavy metal/ferromagnet interfaces in generating\ncurrent-induced spin-orbit torques. However, the strong influence of the\nspin-orbit-derived Dzyaloshinskii-Moriya interaction (DMI) on spin textures in\nthese materials is now becoming apparent. Recent reports suggest DMI-stabilized\nhomochiral domain walls (DWs) can be driven with high efficiency by spin torque\nfrom the spin Hall effect. However, the influence of the DMI on the\ncurrent-induced magnetization switching has not been explored nor is yet\nwell-understood, due in part to the difficulty of disentangling spin torques\nand spin textures in nano-sized confined samples. Here we study the\nmagnetization reversal of perpendicular magnetized ultrathin dots, and show\nthat the switching mechanism is strongly influenced by the DMI, which promotes\na universal chiral non-uniform reversal, even for small samples at the\nnanoscale. We show that ultrafast current-induced and field-induced\nmagnetization switching consists on local magnetization reversal with domain\nwall nucleation followed by its propagation along the sample. These findings,\nnot seen in conventional materials, provide essential insights for\nunderstanding and exploiting chiral magnetism for emerging spintronics\napplications."
    },
    {
        "anchor": "Generic Miniband Structure of Graphene on a Hexagonal Substrate: Using a general symmetry-based approach, we provide a classification of\ngeneric miniband structures for electrons in graphene placed on substrates with\nthe hexagonal Bravais symmetry. In particular, we identify conditions at which\nthe first moir\\'e miniband is separated from the rest of the spectrum by either\none or a group of three isolated mini Dirac points and is not obscured by\ndispersion surfaces coming from other minibands. In such cases the Hall\ncoefficient exhibits two distinct alternations of its sign as a function of\ncharge carrier density.",
        "positive": "Ultraclean Andreev interferometers: Coupling a two-terminal Josephson junction to the stationary modes of the\nelectromagnetic field produces the so-called Fiske resonances. Here, we propose\nanother mechanism based on the exchange between the static Andreev bound states\n(ABS) and a nonequilibrium Fermi surface in an ultraclean multiterminal device.\nAs a simple model, we consider an effective $S_a$-$N_{eff}$-$S_b$ double\njunction connecting the superconductors $S_a$ and $S_b$ to the infinite central\nnormal metal $N_{eff}$. We find that the underlying microscopic process of\nphase-sensitive Andreev reflection (phase-AR) produces the possibility of an\ninversion, that is, the conductance can be larger at half-flux quantum than in\nzero field. The inversion-noninversion alternate as the bias voltage is\nincreased. In addition, if the central region $N_{eff}$ is an integrable\nbilliard connected to an infinite normal reservoir, we find that the standard\nABS are replaced by one- and two-particle Andreev resonances that can be probed\nby the bias voltage. Finally, we find that, in the corresponding\nall-superconducting Andreev interferometer, the superconducting gap produces\nprotection against the short relaxation time of the quasiparticle continua if\nthe time periodic dynamics is treated as a perturbation. The spectrum of the\ntwo-particle resonances is then sparse inside the spectrum of the pairs of\none-particle resonances. Our work supports the nonFloquet intrinsic resonances\nin two-dimensional metal-based Andreev interferometers, and challenges the\nFloquet theory of multiterminal Josephson junctions."
    },
    {
        "anchor": "Ballistic Thermal Transistor of Dielectric Four-terminal Nanostructures: We report a theoretical model for a thermal transistor in dielectric\nfour-terminal nanostructures based on mesoscopic ballistic phonon transport, in\nwhich a steady thermal flow condition of system is obtained to set up the\ntemperature field effect of gate. In the environment, thermal flow shows the\ntransisting behaviors at low temperatures: saturation, asymmetry, and\nrectification. The phenomena can be explained reasonably by the nonlinear\nvariation of the temperature dependence of propagating phonon modes in\nterminals. The results suggest the possibility of the novel nano-thermal\ntransistor fabrication.",
        "positive": "Designer Flat Bands in Quasi-One-Dimensional Atomic Lattices: Certain lattices with specific geometries have one or more spectral bands\nthat are strictly flat, i.e. the electron energy is independent of the\nmomentum. This can occur robustly irrespective of the specific couplings\nbetween the lattices sites due to the lattice symmetry, or it can result from\nfine-tuned couplings between the lattice sites. While the theoretical picture\nbehind flat electronic bands is well-developed, experimental realization of\nthese lattices has proven challenging. Utilizing scanning tunnelling microscopy\n(STM) and spectroscopy (STS), we manipulate individual vacancies in a chlorine\nmonolayer on Cu(100) to construct various atomically precise 1D lattices with\nengineered flat bands. We realize experimentally both gapped and gapless flat\nband systems with single or multiple flat bands. We also demonstrate\ntuneability of the energy of the flat bands and how they can be switched \"on\"\nand \"off\" by breaking and restoring the symmetry of the lattice geometry. The\nexperimental findings are corroborated by tight-binding calculations. Our\nresults constitute the first experimental realizations of engineered flat bands\nin a 1D solid-state system and pave the way towards the construction of e.g.\ntopological flat band systems and experimental tests of flat-band-assisted\nsuperconductivity in a fully controlled system."
    },
    {
        "anchor": "Bright single InAsP quantum dots at telecom wavelengths in\n  position-controlled InP nanowires: the role of the photonic waveguide: We report on the site-selected growth of bright single InAsP quantum dots\nembedded within InP photonic nanowire waveguides emitting at telecom\nwavelengths. We demonstrate a dramatic dependence of the emission rate on both\nthe emission wavelength and the nanowire diameter. With an appropriately\ndesigned waveguide, tailored to the emission wavelength of the dot, an increase\nin count rate by nearly two orders of magnitude (0.4kcps to 35kcps) is obtained\nfor quantum dots emitting in the telecom O-band. Using\nemission-wavelength-optimised waveguides, we demonstrate bright, narrow\nlinewidth emission from single InAsP quantum dots with an unprecedented tuning\nrange from 880nm to 1550nm. These results pave the way towards efficient single\nphoton sources at telecom wavelengths using deterministically grown InAsP/InP\nnanowire quantum dots.",
        "positive": "The influence of the distribution function of ferroelectric\n  nanoparticles sizes on their electrocaloric and pyroelectric properties: We consider a model of a nanocomposite based on non-interacting spherical\nsingle-domain ferroelectric nanoparticles of various sizes embedded in a\ndielectric matrix. The size distribution function of these nanoparticles is\nselected as a part of the Gaussian distribution from minimum to maximum radius\n(truncated normal distribution). For such nanocomposites, we calculate the\ndependences of the reversible part of the electric polarization, the\nelectrocaloric temperature change, and the dielectric permittivity on the\nexternal electric field, which have the characteristic form of hysteresis\nloops. We then analyze the change in the shape of the hysteresis loops relative\nto the particle size distribution parameters. We demonstrate that for the same\nmean-square dispersion, the remanent polarization, coercive field, dielectric\npermittivity maximums, maximums and minimums of the electrocaloric temperature\nchange depend most strongly on the most probable radius, moderately depend on\nthe dispersion, and have the weakest dependency on the nanoparticle maximum\nradius. We calculated and analyzed the dependences of pyroelectric figures of\nmerit on the average radius of the nanoparticles in the composite. The\ndependences confirm the presence of a phase transition induced by the size of\nthe nanoparticles, which is characterized by the presence of a maxima near the\ncritical average radius of the particles, the value of which increases with\nincreasing dispersion of the distribution function."
    },
    {
        "anchor": "Functionalized high-speed magnon-polaritons resulting from the magnetic\n  antenna effect: Magnon-polaritons (MPs) refer to a light--magnon coupled state and can\npotentially act as information carriers, possibly enabling charge-free\ncomputation. However, the light--magnon coupling is inherently weak. To achieve\nsufficiently strong coupling, a large ferromagnet or coupling with a microwave\ncavity is necessary. Herein, we theoretically propose a fundamental platform\nfor magnonic and magnon--optical information storage devices and discuss the\ntransport properties of MP's. The proposed multi-layered structure overcomes\nthe aforementioned issues. Owing to the waveguide modes, magnons placed in a\nnanometer-thin layer are strongly coupled with light, exhibiting rich\nfunctionalities of thick-layer MPs via the `magnetic antenna effect'. Thus, the\nthin-layer MPs are faster, and the direction is switchable. The results of this\nstudy will enable the integration of ferromagnetic micro and nanostructures for\nMP-based information devices without any restrictions due to cavities.",
        "positive": "Landau quantization of nearly degenerate bands, and full symmetry\n  classification of avoided Landau-level crossings: Semiclassical quantization rules compactly describe the energy dispersion of\nLandau levels, and are predictive of quantum oscillations in transport and\nthermodynamic quantities. Such rules -- as formulated by Onsager, Lifshitz and\nRoth -- apply when the spin-orbit interaction dominates over the Zeeman\ninteraction (or vice versa), but does not generally apply when the two\ninteractions are comparable in strength. In this work, we present a generalized\nquantization rule which treats the spin-orbit and Zeeman interactions on equal\nfooting, and therefore has wider applicability to spin-orbit-coupled materials\nlacking a spatial inversion center, or having magnetic order. More generally,\nour rule describes the Landau quantization of any number of nearly degenerate\nenergy bands -- in any symmetry class. The resultant Landau-level spectrum is\ngenerically non-equidistant but may contain spin (or pseudospin) degeneracies.\nTo tune to such degeneracies in the absence of crystalline point-group\nsymmetries, three real parameters are needed. We have exhaustively identified\nall symmetry classes of cyclotron orbits for which this number is reduced from\nthree, thus establishing symmetry-enforced 'non-crossing rules' for Landau\nlevels. In particular, only one parameter is needed in the presence of spatial\nrotation or inversion; this single parameter may be the magnitude or\norientation of the field. Signatures of single-parameter tunability include (i)\na smooth crossover between period-doubled and -undoubled quantum oscillations\nin the low-temperature Shubnikov-de Haas effect, as well as (ii) 'magic-angle'\nmagnetoresistance oscillations. We demonstrate the utility of our quantization\nrule, as well as the tunability of Landau-level degeneracies, for the\nRashba-Dresselhaus two-dimensional electron gas -- subject to an arbitrarily\noriented magnetic field."
    },
    {
        "anchor": "Wave Functions Statistics at Quantum Hall Critical Point: I elaborate on the earlier suggestion that the model describing the plateaux\ntransition in Integer Quantum Hall effect scales to a particular point on the\nline of critical points of a theory with a higher symmetry",
        "positive": "Floquet Theory of Electron Waiting Times in Quantum-Coherent Conductors: We present a Floquet scattering theory of electron waiting time distributions\nin periodically driven quantum conductors. We employ a second-quantized\nformulation that allows us to relate the waiting time distribution to the\nFloquet scattering matrix of the system. As an application we evaluate the\nelectron waiting times for a quantum point contact, modulating either the\napplied voltage (external driving) or the transmission probability (internal\ndriving) periodically in time. Lorentzian-shaped voltage pulses are of\nparticular interest as they lead to the emission of clean single-particle\nexcitations as recently demonstrated experimentally. The distributions of\nwaiting times provide us with a detailed characterization of the dynamical\nproperties of the quantum-coherent conductor in addition to what can be\nobtained from the shot noise or the full counting statistics."
    },
    {
        "anchor": "Electronic and magnetic properties of single-layer MPX$_3$ metal\n  phosphorous trichalcogenides: We systematically investigate the electronic structure and magnetic\nproperties of two dimensional (2D) MPX$_3$ (M= V, Cr, Mn, Fe, Co, Ni, Cu, Zn,\nand X = S, Se, Te) transition metal chacogenophosphates to examine their\npotential role as single-layer van der Waals materials that exhibit magnetic\norder. Our {\\em ab initio} calculations predict that most of these single-layer\nmaterials are antiferromagnetic semiconductors. The band gaps of the\nantiferromagnetic states decrease as the atomic number of the chalcogen atom\nincreases (from S to Se, Te), leading in some cases to half-metallic\nferromagnetic states or to non-magnetic metallic states. We find that the phase\ntransition from antiferromagnetic semiconductor to ferromagnetic half-metal can\nbe controlled by gating or by strain engineering. The sensitive interdependence\nwe find between magnetic, structural, and electronic properties establishes the\npotential of this 2D materials class for applications in spintronics.",
        "positive": "Electronic transport in ferromagnetic conductors with inhomogeneous\n  magnetic order parameter -- domain-wall resistance: We microscopically derive transport equations for the conduction electrons in\nferromagnetic materials with an inhomogeneous magnetization profile. Our\nquantum kinetic approach includes elastic scattering and anisotropic spin-flip\nscattering at magnetic impurities. In the diffusive limit, we calculate the\nresistance through a domain wall and find that the domain-wall resistance can\nbe positive or negative. In the limit of long domain walls we derive analytical\nexpressions and compare them with existing works, which used less general\nmodels or different theoretical frameworks."
    },
    {
        "anchor": "Optical generation and detection of pure valley current in monolayer\n  transition metal dichalcogenides: We propose a practical scheme to generate a pure valley current in monolayer\ntransition metal dichalcogenides by one-photon absorption of linearly polarized\nlight. We show that the pure valley current can be detected by either\nphotoluminescence measurements or the ultrafast pump-probe technique. Our\nmethod, together with the previously demonstrated generation of valley\npolarization, opens up the exciting possibility of ultrafast optical-only\nmanipulation of the valley index. The tilted field effect on the valley current\nin experiment is also discussed.",
        "positive": "Electric Field Effects on Armchair MoS2 Nanoribbons: {\\it Ab initio} density functional theory calculations are performed to\ninvestigate the electronic structure of MoS$_2$ armchair nanoribbons in the\npresence of an external static electric field. Such nanoribbons, which are\nnonmagnetic and semiconducting, exhibit a set of weakly interacting edge states\nwhose energy position determines the band-gap of the system. We show that, by\napplying an external transverse electric field, $E_\\mathrm{ext}$, the\nnanoribbons band-gap can be significantly reduced, leading to a metal-insulator\ntransition beyond a certain critical value. Moreover, the presence of a\nsufficiently high density of states at the Fermi level in the vicinity of the\nmetal-insulator transition leads to the onset of Stoner ferromagnetism that can\nbe modulated, and even extinguished, by $E_\\mathrm{ext}$. In the case of\nbi-layer nanoribbons we further show that the band-gap can be changed from\nindirect to direct by applying a transverse field, an effect which might be of\nsignificance for opto-electronics applications."
    },
    {
        "anchor": "Observation of second-order topological insulators in sonic crystals: Topological insulators with unique gapless edge states have revolutionized\nthe understanding of electronic properties in solid materials. These gapless\nedge states are dictated by the topological invariants associated with the\nquantization of generalized Berry phases of the bulk energy bands through the\nbulk-edge correspondence, a paradigm that can also be extended to acoustic and\nphotonic systems. Recently, high-order topological insulators (HOTIs) are\nproposed and observed, where the bulk topological invariants result in gapped\nedge states and in-gap corner or hinge states, going beyond the conventional\nbulk-edge correspondence. However, the existing studies on HOTIs are restricted\nto tight-binding models which cannot describe the energy bands of conventional\nsonic/photonic crystals that are due to multiple Bragg scatterings. Here, we\nreport theoretical prediction and experimental observation of acoustic\nsecond-order topological insulators (SOTI) in two-dimensional (2D) sonic\ncrystals (SCs) beyond the tight-binding picture. We observe gapped edge states\nand degenerate in-gap corner states which manifest bulk-edge correspondence in\na hierarchy of dimensions. Moreover, topological transitions in both the bulk\nand edge states can be realized by tuning the angle of the meta-atoms in each\nunit-cell, leading to various conversion among bulk, edge and corner states.\nThe emergent properties of the acoustic SOTIs open up a new route for\ntopological designs of robust localized acoustic modes as well as topological\ntransfer of acoustic energy between 2D, 1D and 0D modes.",
        "positive": "Quantum dot dephasing by fractional quantum Hall edge states: We consider the dephasing rate of an electron level in a quantum dot, placed\nnext to a fluctuating edge current in the fractional quantum Hall effect. Using\nperturbation theory, we show that this rate has an anomalous dependence on the\nbias voltage applied to the neighboring quantum point contact, which originates\nfrom the Luttinger liquid physics which describes the Hall fluid. General\nexpressions are obtained using a screened Coulomb interaction. The dephasing\nrate is strictly proportional to the zero frequency backscattering current\nnoise, which allows to describe exactly the weak to strong backscattering\ncrossover using the Bethe-Ansatz solution."
    },
    {
        "anchor": "Peculiar electronic states, symmetries and Berry phases in irradiated\n  $\u03b1$-$T_3$ materials: We have laid out the results of a rigorous theoretical investigation into the\nresponse of electron dressed states, i.e., interacting Floquet states arising\nfrom the off-resonant coupling of Dirac spin-1 electrons in the $\\alpha$-$T_3$\nmodel, to external radiation with various polarizations. Specifically, we have\nexamined the role played by the parameter $\\alpha$ that is a measure of the\ncoupling strength with the additional atom at the center of the honeycomb\ngraphene lattice and which, when varied, continuously gives a different Berry\nphase. We have found that the electronic properties of the $\\alpha$ -$T_3$\nmodel (consisting of a flat band and two cones) could be modified depending on\nthe polarization of the imposed irradiation. We have demonstrated that under\nelliptically-polarized light the low-energy band structure of such lattice\ndirectly depends on the valley index $\\tau$. We have obtained and analyzed the\ncorresponding wave functions, their symmetries and the corresponding Berry\nphases, and revealed that such phases could be finite even for a dice lattice,\nwhich has not been observed in the absence of the dressing field. This results\nlead to possible radiation-generated band structure engineering, as well as\nexperimental and technological realization of such optoelectronic devices and\nphotonic crystals.",
        "positive": "Phonon Magnetic Moment from Electronic Topological Magnetization: The traditional theory of magnetic moments for chiral phonons is based on the\npicture of the circular motion of the Born effective charge, typically yielding\na small fractional value of the nuclear magneton. Here we investigate the\nadiabatic evolution of electronic states induced by lattice vibration of a\nchiral phonon and obtain an electronic orbital magnetization in the form of a\ntopological second Chern form. We find that the traditional theory needs to be\nrefined by introducing a $\\bm{k}$ resolved Born effective charge, and identify\nanother contribution from the phonon-modified electronic energy together with\nthe momentum-space Berry curvature. The second Chern form can diverge when\nthere is a Yang's monopole near the parameter space of interest as illustrated\nby considering a phonon at the Brillouin zone corner in a gaped graphene model.\nWe also find large magnetic moments for the optical phonon in bulk topological\nmaterials where non-topological contribution is also important. The magnetic\nmoment experiences a sign change when the band inversion happens."
    },
    {
        "anchor": "Mesoscopic Quantum Thermo-mechanics: a new frontier of experimental\n  physics: Within the last decade, experimentalists have demonstrated their impressive\nability to control mechanical modes within mesoscopic objects down to the\nquantum level: it is now possible to create mechanical Fock states, to entangle\nmechanical modes from distinct objects, store quantum information or transfer\nit from one quantum bit to another, among the many possibilities found in\ntoday's literature. Indeed mechanics is quantum, very much like spins or\nelectromagnetic degrees of freedom. And all of this is in particular referred\nto as a new engineering resource for quantum technologies. But there is also\nmuch more beyond this utilitarian aspect: invoking the original discussions of\nBraginsky and Caves where a quantum oscillator is thought of as a quantum\ndetector for a classical field, namely a gravitational wave, it is also a\nunique sensing capability for quantum fields. The subject of study is then the\nbaths to which the mechanical mode is coupled to, let them be known or unknown\nin nature. This Letter is about this new potentiality, that addresses\nstochastic thermodynamics, potentially down to its quantum version, the search\nfor a fundamental underlying (random) field postulated in recent theories that\ncan be affiliated to the class of the Wave-function Collapse models, and more\ngenerally open questions of Condensed Matter like the actual nature of the\nelusive (and ubiquitous) Two-Level Systems present within all mechanical\nobjects. But such research turns out to be much more demanding than the usage\nof a few quantum mechanical modes: all the known baths have to be identified,\nexperiments have to be conducted in-equilibrium, and the word \"mechanics\" needs\nto be justified by a real ability to move substantially the centre-of-mass when\na proper drive tone is applied to the system.",
        "positive": "Moir\u00e9 band structures of twisted phosphorene bilayers: We report on the theoretical electronic spectra of twisted phosphorene\nbilayers exhibiting moir\\'e patterns, as computed by means of a continuous\napproximation to the moir\\'e superlattice Hamiltonian. Our model is constructed\nby interpolating between effective $\\Gamma$-point conduction- and valence-band\nHamiltonians for the different stacking configurations approximately realized\nacross the moir\\'e supercell, formulated on symmetry grounds. We predict the\nrealization of three distinct regimes for $\\Gamma$-point electrons and holes at\ndifferent twist angle ranges: a Hubbard regime for small twist angles $\\theta <\n2^\\circ$, where the electronic states form arrays of quantum-dot-like states,\none per moir\\'e supercell; a Tomonaga-Luttinger regime at intermediate twist\nangles $2^\\circ < \\theta \\lesssim 10^\\circ$, characterized by the appearance of\narrays of quasi-1D states; and finally, a ballistic regime at large twist\nangles $\\theta \\gtrsim 10^\\circ$, where the band-edge states are delocalized,\nwith dispersion anisotropies modulated by the twist angle. Our method correctly\nreproduces recent results based on large-scale ab initio calculations at a much\nlower computational cost, and with fewer restrictions on the twist angles\nconsidered."
    },
    {
        "anchor": "Electron Density Dependence of in-plane Spin Relaxation Anisotropy in\n  GaAs/AlGaAs Two-Dimensional Electron Gas: We investigated the spin dynamics of two-dimensional electrons in (001)\nGaAs/AlGaAs heterostructure using the time resolved Kerr rotation technique\nunder a transverse magnetic field. The in-plane spin lifetime is found to be\nanisotropic below 150k due to the interference of Rashba and Dresselhaus\nspin-orbit coupling and D'yakonov-Perel' spin relaxation. The ratio of in-plane\nspin lifetimes is measured directly as a function of temperature and pump\npower, showing that the electron density in 2DEG channel strongly affects the\nRashba spin-orbit coupling.",
        "positive": "Spin-triplet $f$-wave symmetry in superconducting monolayer $MoS_2$: The proximity-induced spin-triplet $f$-wave symmetry pairing in a monolayer\nmolybdenum disulfide-superconductor hybrid features an interesting\nelectron-hole excitations and also effective superconducting subgap, giving\nrise to a distinct Andreev resonance state. Owing to the complicated Fermi\nsurface and momentum dependency of $f$-wave pair potential, monolayer $MoS_2$\nwith strong spin-orbit coupling can be considered an intriguing structure to\nreveal the superconducting state. Actually, this can be possible by calculating\nthe peculiar spin-valley polarized transport of quasiparticles in a related\nnormal metal/superconductor junction. We theoretically study the formation of\neffective gap at the interface and resulting normalized conductance on top of a\n$MoS_2$ under induction of $f$-wave order parameter, using\nBloder-Tinkham-Klapwijk formalism. The superconducting excitations shows that\nthe gap is renormalized by a \\textit{bias limitation} coefficient including\ndynamical band parameters of monolayer $MoS_2$, especially, ones related to the\nSchrodinger-type momentum of Hamiltonian. The effective gap is more sensitive\nto the n-doping regime of superconductor region. The signature of spin-orbit\ncoupling, topological and asymmetry mass-related terms in the resulting subgap\nconductance and, in particular, maximum conductance is presented. In the\nabsence of topological term, the effective gap reaches to its maximum value.\nThe unconventional nature of superconducting order leads to the appearance of\nzero-bias conductance. In addition, the maximum value of conductance can be\ncontrolled by tuning the doping level of normal and superconductor regions."
    },
    {
        "anchor": "Dynamic response functions of two-dimensional Dirac fermions with\n  screened Coulomb and short-range interactions: We consider a screened Coulomb interaction between electrons in graphene and\ndetermine their dynamic response functions, such as a longitudinal and a\ntransverse electric conductivity and a polarization function and compare them\nto the corresponding quantities in the short-range interaction model. The\ncalculations are performed to all orders for short-range interaction by taking\ninto account the self-energy renormalization of the electron velocity and using\na ladder approximation to account for the vertex corrections, ensuring that the\nWard identity (charge conservation law) is satisfied. Our findings predict a\nresonant response of interacting electron-hole pairs at a particular frequency\nbelow the threshold $qv=\\omega$ and further predict an instability for\nsufficiently strong interactions.",
        "positive": "Prospects of cooling a mechanical resonator with a transmon qubit in\n  c-QED setup: Hybrid devices based on the superconducting qubits have emerged as a\npromising platform for controlling the quantum states of macroscopic\nresonators. The nonlinearity added by a qubit can be a valuable resource for\nsuch control. Here we study a hybrid system consisting of a mechanical\nresonator longitudinally coupled to a transmon qubit. The qubit readout can be\ndone by coupling to a readout mode like in c-QED setup. The coupling between\nthe mechanical resonator and transmon qubit can be implemented by modulation of\nthe SQUID inductance. In such a tri-partite system, we analyze the steady-state\noccupation of the mechanical mode when all three modes are dispersively\ncoupled. We use the quantum-noise and the Lindblad formalism to show that the\nsideband cooling of the mechanical mode to its ground state is achievable. We\nfurther experimentally demonstrate that measurements of the thermomechanical\nmotion is possible in the dispersive limit, while maintaining a large coupling\nbetween qubit and mechanical mode. Our theoretical calculations suggest that\nsingle-photon strong coupling is within the experimental reach in such hybrid\ndevices."
    },
    {
        "anchor": "Controlled Operations in a Strongly Correlated Two-Electron Quantum Ring: We have analyzed the electronic spectrum and wave function characteristics of\na strongly correlated two-electron quantum ring with model parameters close to\nthose observed in experiments. The analysis is based on an exact\ndiagonalization of the Hamiltonian in a large B-spline basis. We propose a new\nqubit pair for storing quantum information, where one component is stored in\nthe total electron spin and one multivalued \"quMbit\" is represented by the\ntotal angular momentum. In this scheme the controlled NOT (CNOT) quantum gate\nis demonstrated with near 100% fidelity for a realistic far infrared\nelectromagnetic pulse.",
        "positive": "Role of coherence in resistance quantization: The quantization of resistances in the quantum Hall effect and ballistic\ntransport through quantum point contacts is compared with the quantization of\nthe charge relaxation resistance of a coherent mesoscopic capacitor. While the\nformer two require the existence of a perfectly transmitting channel, the\ncharge relaxation resistance remains quantized for arbitrary backscattering.\nThe quantum Hall effect and the quantum point contact require only local phase\ncoherence. In contrast quantization of the charge relaxation resistance\nrequires global phase coherence."
    },
    {
        "anchor": "Quantum Hall Conductivity in a Landau Type Model with a Realistic\n  Geometry II: We use a mathematical framework that we introduced in a previous paper to\nstudy geometrical and quantum mechanical aspects of a Hall system with finite\nsize and general boundary conditions. Geometrical structures control possibly\nthe integral or fractionnal quantization of the Hall conductivity depending on\nthe value of $NB/2\\pi$ ($N$ is the number of charge carriers and $B$ is the\nmagnetic field). When $NB/2\\pi$ is irrationnal, we show that monovalued wave\nfunctions can be constructed only on the graph of a free group with two\ngenerators. When $NB/2\\pi$ is rationnal, the relevant space becomes a\npuncturated Riemann surface. We finally discuss our results from a\nphenomenological viewpoint.",
        "positive": "Coulomb drag of excitons in Bose-Fermi mixtures: We develop a microscopic theory of the Coulomb drag effect in a hybrid system\nconsisting of spatially separated two-dimensional quantum gases of degenerate\nelectrons and dipolar excitons. We consider both the normal-phase and\ncondensate regimes of the exciton subsystem and investigate the cross-mobility\nof the system being the kinetic coefficient, which couples the static electric\nfield applied to the electron layer with the particle density current (flux) in\nthe exciton subsystem. We study the temperature dependence of the\ncross-mobility and its dependence on the interlayer separation. We show that\nexciton-exciton interaction plays a dramatic role. If the exciton gas is in the\nnormal phase, then the screening of interlayer interaction by the exciton\nsubsystem results in an exponential damping of the cross-mobility with the\ndecrease of temperature, while at low temperatures, the interactions result in\na robust bosonic transport due to the emergence of the Bogoliubov\nquasiparticles."
    },
    {
        "anchor": "Probing Magnetism in Insulating Cr2Ge2Te6 by Induced Anomalous Hall\n  Effect in Pt: Two-dimensional ferromagnet Cr2Ge2Te6 (CGT) is so resistive below its Curie\ntemperature that probing its magnetism by electrical transport becomes\nextremely difficult. By forming heterostructures with Pt, however, we observe\nclear anomalous Hall effect (AHE) in 5 nm thick Pt deposited on thin (< 50 nm)\nexfoliated flakes of CGT. The AHE hysteresis loops persist to ~ 60 K, which\nmatches well to the Curie temperature of CGT obtained from the bulk\nmagnetization measurements. The slanted AHE loops with a narrow opening\nindicate magnetic domain formation, which is confirmed by low-temperature\nmagnetic force microscopy (MFM) imaging. These results clearly demonstrate that\nCGT imprints its magnetization in the AHE signal of the Pt layer. Density\nfunctional theory calculations of CGT/Pt heterostructures suggest that the\ninduced ferromagnetism in Pt may be primarily responsible for the observed AHE.\nOur results establish a powerful way of investigating magnetism in 2D\ninsulating ferromagnets which can potentially work for monolayer devices.",
        "positive": "Beating maps of singlet fission: Full-quantum simulation of coherent\n  two-dimensional electronic spectroscopy in organic aggregates: The coherent two-dimensional (2D) electronic spectra with respect to the\nsinglet fission (SF) process in organic molecular aggregates are simulated by\nthe Davydov ansatz combined with the Frenkel-Dirac time-dependent variational\nalgorithm. By virtue of the full-quantum dynamical approach, we are able to\nidentify the signals of triplet excitation in the excite-state absorption\ncontribution of the 2D spectra. In order to discuss whether a mediative\ncharge-transfer (CT) state is necessary to SF, we increase the CT-state energy\nand find, in a theoretical manner, the beating signal related to the triplet is\ninhibited. The vibronic coherence is then studied in the beating maps for both\nthe ground and excited state. Except for the normal beating modes adhering to\nthe relevant electronic state, we observe signals that are explicitly related\nto the triplet excitations. The pathways of transition corresponding to these\nsignals are clarified in the respective Feynman diagram, which can help the\nexperimenters determine the physical origin of relevant measurements."
    },
    {
        "anchor": "Spin noise spectroscopy of a single-quantum-well microcavity: We report on the first experimental observation of spin noise in a single\nsemiconductor quantum well embedded into a microcavity. The great\ncavity-enhanced sensitivity to fluctuations of optical anisotropy has allowed\nus to measure the Kerr rotation and ellipticity noise spectra in the strong\ncoupling regime. The spin noise spectra clearly show two resonant features: a\nconventional magneto-resonant component shifting towards higher frequencies\nwith magnetic field and an unusual \"nonmagnetic\" component centered at zero\nfrequency and getting suppressed with increasing magnetic field. We attribute\nthe first of them to the Larmor precession of free electron spins, while the\nsecond one being presumably due to hyperfine electron-nuclei spin interactions.",
        "positive": "Stimulated spin noise in an activated crystal: In the spin noise spectroscopy, the magnetic susceptibility spectrum is known\nto be provided by the spin-system untouched by any external perturbation, or,\nbetter to say, disturbed only by its thermal bath. We propose a new version of\nthe spin noise spectroscopy, with the detected magnetization (Faraday-rotation)\nnoise being stimulated by an external fluctuating magnetic field with a\nquasi-white spectrum. Experimental study of the stimulated spin noise performed\non a $\\text{BaF}_2 : \\text{U}^{3+}$ crystal in a longitudinal magnetic field\nhas revealed specific features of this approach and allowed us to identify the\nVan-Vleck and population-related contributions to the AC susceptibility of the\nsystem and to discover unusual magnetic-field dependence of the longitudinal\nspin relaxation rate in low magnetic fields. It is shown that spectra of the\nstimulated and spontaneous spin noise, being both closely related to the\nspin-system magnetic susceptibility, are still essentially different.\nDistinctions between the two types of the spin-noise spectra and two approaches\nto the spin noise spectroscopy are discussed."
    },
    {
        "anchor": "Levitons in superconducting point contacts: We investigate the transport properties of a superconducting quantum point\ncontact in the presence of an arbitrary periodic drive. In particular, we\ncalculate the dc current and noise in the tunnel limit, obtaining general\nexpressions in terms of photoassisted probabilities. Interesting features can\nbe observed when the frequency is comparable to the gap. Here, we show that\nquantized Lorentzian pulses minimize the excess noise, further strengthening\nthe hierarchy among different periodic drives observed in the electron quantum\noptics domain. In this regime, the excess noise is directly connected to the\noverlap between electron and hole energy distributions driven out of\nequilibrium by the applied voltage. In the adiabatic limit, where the frequency\nof the drive is very small compared to the superconducting gap, we recover the\nconventional Shapiro-spikes physics in the supercurrent.",
        "positive": "Integer and Fractional Quantum Hall Effect in a Strip of Stripes: We study anisotropic stripe models of interacting electrons in the presence\nof magnetic fields in the quantum Hall regime with integer and fractional\nfilling factors. The model consists of an infinite strip of finite width that\ncontains periodically arranged stripes (forming supercells) to which the\nelectrons are confined and between which they can hop with associated magnetic\nphases. The interacting electron system within the one-dimensional stripes are\ndescribed by Luttinger liquids and shown to give rise to charge and spin\ndensity waves that lead to periodic structures within the stripe with a\nreciprocal wavevector 8k_F. This wavevector gives rise to Umklapp scattering\nand resonant scattering that results in gaps and chiral edge states at all\nknown integer and fractional filling factors \\nu. The integer and odd\ndenominator filling factors arise for a uniform distribution of stripes,\nwhereas the even denominator filling factors arise for a non-uniform stripe\ndistribution. We calculate the Hall conductance via the Streda formula and show\nthat it is given by \\sigma_H=\\nu e^2/h for all filling factors. We show that\nthe composite fermion picture follows directly from the condition of the\nresonant Umklapp scattering."
    },
    {
        "anchor": "Universal Landauer conductance in chiral symmetric 2d systems: We study transport properties of an arbitrarily shaped ultraclean graphene\nsheet, adiabatically connected to leads,composed by the same material. If the\nlocalized interactions do not destroy chiral symmetry, we show that the\nconductance is quantized, since it is dominated by the quasi one-dimensional\nleads. As an example, we show that smooth structural deformations of the\ngraphene plane do not modify the conductance quantization.",
        "positive": "Full Optical Control of Topological Transitions in Polariton Chern\n  Insulator Analog: Exciton-polariton lattices allow to implement topologically protected\nphotonic edge states at optical frequencies. Taking advantage of the\ninteracting character of polaritons, we show that several topological phases,\nbelonging to the Quantum Anomalous Hall family, can occur in polariton graphene\nwith the TE-TM spin-orbit coupling and an effective Zeeman field. This Zeeman\nfield can be entirely controlled by the non-linearity of the macro-occupied\nmode created by circularly polarized resonant pumping. The topological phases\nfound are distinct from the ones of normal graphene in presence of a\ncombination of Rashba and Zeeman field."
    },
    {
        "anchor": "Transiently changing shape of the photon number distribution in a\n  quantum-dot--cavity system driven by chirped laser pulses: We have simulated the time evolution of the photon number distribution in a\nsemiconductor quantum dot-microcavity system driven by chirped laser pulses and\ncompare with unchirped results. When phonon interactions with the dot are\ndisregarded - thus corresponding to the limit of atomic cavity systems -\nchirped pulses generate photon number distributions that change their shape\ndrastically in the course of time. Phonons have a strong and qualitative impact\non the photon statistics. The asymmetry between phonon absorption and emission\ndestroys the symmetry of the photon distributions obtained for positive and\nnegative chirps. While for negative chirps transient distributions resembling\nthermal ones are observed, for positive chirps the photon number distribution\nstill resembles its phonon-free counterpart but with overall smoother shapes.\nIn sharp contrast, using unchirped pulses of the same pulse area and duration\nwave-packets are found that move up and down the Jaynes-Cummings ladder with a\nbell-shape that changes little in time. For shorter pulses and lower driving\nstrength Rabi-like oscillations occur between low photon number states. For all\nconsidered excitation conditions transitions between sub- and super-Poissonian\nstatistics are found at certain times. For resonant driving with low intensity\nthe Mandel parameter oscillates and is mostly negative, which indicates a\nnon-classical state in the cavity field. Finally, we show that it is possible\nthat the Mandel parameter dynamically approaches zero and still the photon\ndistribution exhibits two maxima and thus is far from being a Poissonian.",
        "positive": "Time evolution of an entangled initial state in coupled quantum dots\n  with Coulomb correlations: We analyzed the dynamics of the initial singlet electronic state in the two\ninteracting single-level quantum dots (QDs) with Coulomb correlations, weakly\ntunnel coupled to an electronic reservoir. We obtained correlation functions of\nall orders for the electrons in the QDs by decoupling high-order correlations\nbetween localized and band electrons in the reservoir. We proved that for\narbitrary mixed state the concurrence and entanglement can be determined from\nthe average value of particular combinations of electron's pair correlation\nfunctions. Analysis of the pair correlation functions time evolution allows to\nfollow the changes of concurrence and entanglement during the relaxation\nprocesses. We investigated the dependence of concurrence on the value of\nCoulomb interaction and the energy levels spacing and found it's non-monotonic\nbehavior in the non-resonant case. We also demonstrated that the behavior of\npair correlation functions for two-electron entangled state in coupled QDs\npoints to the fulfillment of the Hund's rule for the strong Coulomb\ninteraction. We revealed the appearance of dynamical inverse occupation of the\nQDs energy levels during the relaxation processes. Our results open up further\nperspectives in solid state quantum information based on the controllable\ndynamics of the entangled electronic states."
    },
    {
        "anchor": "Observation of topological crystalline insulator surface states on\n  (111)-oriented Pb$_{1-x}$Sn$_{x}$Se films: We present angle resolved photoemission spectroscopy measurements of the\nsurface states on in-situ grown (111) oriented films of Pb$_{1-x}$Sn$_{x}$Se, a\nthree dimensional topological crystalline insulator. We observe surface states\nwith Dirac-like dispersion at $\\bar{\\Gamma}$ and $\\bar{M}$ in the surface\nBrillouin zone, supporting recent theoretical predictions for this family of\nmaterials. We study the parallel dispersion isotropy and Dirac-point binding\nenergy of the surface states, and perform tight-binding calculations to support\nour findings. The relative simplicity of the growth technique is encouraging,\nand suggests a clear path for future investigations into the role of strain,\nvicinality and alternative surface orientations in (Pb,Sn)Se compounds.",
        "positive": "Finite U thermoelectrical transport in graphene based quantum dots: We study the thermoelectrical transports for an interacting dot attached to\ntwo graphene electrodes. Graphene band structure shows a pseudogap density of\nstates that affects strongly the transport properties. In this work, we focus\non the Coulomb blockade regime and derive the expression for Onsager matrix\nO_{ij} that relates the electrical and heat currents with electrical and\nthermal biases in the linear response regime. Our findings show double peak\nstructures for the electrical and thermal conductances versus the dot level in\naccordance with the Coulom blockade phenomenon. Remarkably, however, the\nthermal conductance is much smaller than the electrical conductance, resulting\nin high figure of merit value for some gate voltage. Finally, we report a large\ndeparture from the Wiedemann-Franz law caused mainly by the pseudogap density\nof states in the contacts and weakly affected by interactions."
    },
    {
        "anchor": "Coherent thermal conductance in multilayer photonic crystals: We present an exact calculation of the coherent thermal conductance in a 1-D\nmultilayer photonic crystals (PC) using the S-matrix method. In particular, we\nstudy the thermal conductance in a bilayer structure of slabs of Si/vacuum or\nAl$_2$O$_3$/vacuum by means of the exact expression for the radiative heat\nflux. We compare our results with results obtained in previous works. Our\nresults show that the coupling of surface modes as well as material losses play\na fundamental role in the definition of the thermal conductance of PCs.",
        "positive": "Resonant and phonon-assisted ultrafast coherent control of a single hBN\n  color center: Single-photon emitters in solid-state systems are important building blocks\nfor scalable quantum technologies. Recently, quantum light emitters have been\ndiscovered in the wide-gap van der Waals insulator hBN. These color centers\nhave attracted considerable attention due to their quantum performance at\nelevated temperatures and wide range of transition energies. Here, we\ndemonstrate coherent state manipulation of a single hBN color center with\nultrafast laser pulses and investigate in our joint experiment-theory study the\ncoupling between the electronic system and phonons. We demonstrate that\ncoherent control can not only be performed resonantly on the optical transition\ngiving access to the decoherence but also phonon-assisted, which reveals the\ninternal phonon quantum dynamics. In the case of optical phonons we measure\ntheir decoherence, stemming in part from their anharmonic decay. Dephasing\ninduced by the creation of acoustic phonons manifests as a rapid decrease of\nthe coherent control signal when traveling phonon wave packets are emitted.\nFurthermore, we demonstrate that the quantum superposition between a\nphonon-assisted process and the resonant excitation causes ultrafast\noscillations of the coherent control signal. Our results pave the way for\nultrafast phonon quantum state control on the nanoscale and open up a new\npromising perspective for hybrid quantum technologies."
    },
    {
        "anchor": "Majorana Fermion Rides on a Magnetic Domain Wall: We propose using a mobile magnetic domain wall as a host of zero-energy\nMajorana fermions in a spin-orbit coupled nanowire sandwiched by two\nferromagnetic strips and deposited on an $s$-wave superconductor. The ability\nto control domain walls by thermal means allows to braid Majorana fermions\nnonintrusively, which obey non-Abelian statistics. The analytical solutions of\nMajorana fermions inside domain walls are obtained in the strong spin-orbit\nregime.",
        "positive": "Ising machines with strong bilinear coupling: Networks of coupled parametric resonators (parametrons) hold promise for\nparallel computing architectures. En route to realizing complex networks, we\nreport an experimental and theoretical analysis of two coupled parametrons. In\ncontrast to previous studies, we explore the case of strong bilinear coupling\nbetween the parametrons, as well as the role of detuning. We show that the\nsystem can still operate as an Ising machine in this regime, even though\ncareful calibration is necessary to ensure that the correct solution space is\navailable. Apart from the formation of split normal modes, new states of mixed\nsymmetry are generated. Furthermore, we predict that systems with $N>2$\nparametrons will undergo multiple phase transitions before arriving at a regime\nthat can be equivalent to the Ising problem."
    },
    {
        "anchor": "Josephson and persistent currents in a quantum ring between topological\n  superconductors: In this work, we investigate the spectra in an Aharonov-Bohm quantum-ring\ninterferometer forming a Josephson junction between two topological\nsuperconductors (TSC) nanowires. The TSCs host Majorana bound states at their\nedges, and both the magnetic flux and the superconducting phase difference\nbetween the TSCs are used as control parameters. We use a tight-binding\napproach to model the quantum ring coupled to both TSCs, described by the\nKitaev effective Hamiltonian. We solve the problem by means of exact numerical\ndiagonalization of the Bogoliubov-de Gennes (BdG) Hamiltonian and obtain the\nspectra for two sizes of the quantum ring as a function of the magnetic flux\nand the phase difference between the TSCs. Depending on the size of the quantum\nring and the coupling, the spectra display several patterns. Those are denoted\nas line, point and undulated nodes, together with flat bands, which are\ntopologically protected. The first three patterns can be possibly detected by\nmeans of persistent and Josephson currents. Hence, our results could be useful\nto understand the spectra and their relation with the behavior of the current\nsignals.",
        "positive": "Unusual Tunneling Characteristics of Double-quantum-well\n  Heterostructures: We report tunneling phenomena in double In$_{0.53}$Ga$_{0.47}$As quantum-well\nstructures that are at odds with the conventional parallel-momentum-conserving\npicture of tunneling between two-dimensional systems. We found that the\ntunneling current was mostly determined by the correlation between the emitter\nand the state in one well, and not by that between those in both wells. Clear\nmagnetic-field-dependent features were first observed before the main\nresonance, corresponding to tunneling channels into the Landau levels of the\nwell near the emitter. These facts provide evidence of the violation of\nin-plane momentum conservation in two-dimensional systems."
    },
    {
        "anchor": "Borophene as an extremely high capacity electrode material for Li-ion\n  and Na-ion batteries: Two-dimensional (2D) materials as electrodes is believed to be the trend for\nfuture Li-ion and Na-ion batteries technologies. Here, by using\nfirst-principles methods, we predict that the recently reported borophene (2D\nborn sheet) can serve as an ideal electrode material with high electrochemical\nperformance for both Li-ion and Na-ion batteries. The calculations are\nperformed on the two experimentally stable borophene structures, namely\n\\b{eta}12 and \\c{hi}3 structures. The optimized Li and Na adsorption sites are\nidentified, and the host materials are found to maintain good electric\nconductivity before and after adsorption. Besides advantages including small\ndiffusion barriers and low average open-circuit voltages, most remarkably, the\nstorage capacity can be as high as 1984 mA h g-1 in \\b{eta}12 borophene and\n1240 mA h g-1 in \\c{hi}3 borophene for both Li and Na, which is several times\nhigher than the commercial graphite electrode and is the highest among all the\n2D materials discovered to date. Our results highly support that borophenes can\nbe appealing anode materials for both Li-ion and Na-ion batteries with\nextremely high power density.",
        "positive": "Localization effects on magnetotransport of a disordered Weyl semimetal: We study magnetotransport in a disordered Weyl semimetal taking into account\nlocalization effects exactly. In the vicinity of a Weyl node, a single chiral\nLandau level coexists with a number of conventional non-chiral levels. Disorder\nscattering mixes these topologically different modes leading to peculiar\nlocalization effects. We derive the average conductance as well as the full\ndistribution function of transmission probabilities along the field direction.\nRemarkably, we find that localization of the non-chiral modes is greatly\nenhanced in a strong magnetic field with the typical localization length\nscaling as $1/B$. Technically, we use the non-linear sigma-model formalism with\na topological term describing the chiral states. The problem is solved exactly\nby mapping to an equivalent transfer matrix Hamiltonian."
    },
    {
        "anchor": "Appearance of effective surface conductivity - an experimental and\n  analytic study: Surface conductance measurements on p-type doped germanium show a small but\nsystematic change to the surface conductivity at different length scales. This\neffect is independent of the structure of the surface states. We interpret this\nphenomenon as a manifestation of conductivity changes beneath the surface. This\nhypothesis is confirmed by an analysis of the classical current flow equation.\nWe derive an integral formula for calculating of the effective surface\nconductivity as a function of the distance from a point source. Furthermore we\nderive asymptotic values of the surface conductivity at small and large\ndistances. The actual surface conductivity can only be sampled close to the\ncurrent source. At large distances, the conductivity measured on the surface\ncorresponds to the bulk value.",
        "positive": "Fermi resonance in the Raman spectrum of graphene: We report the observation of an intense anomalous peak at 1608 cm$^{-1}$ in\nthe Raman spectrum of graphene associated to the presence of chromium\nnanoparticles in contact with graphene. Bombardment with an electron beam\ndemonstrates that this peak is distinct from the well studied D$'$ peak\nappearing as defects are created in graphene; the new peak is found non\ndispersive. We argue that the bonding of chromium atoms with carbon atoms\nsoftens the out-of-plane optical (ZO) phonon mode, in such a way that the\nfrequency of its overtone decreases to $2\\omega_{\\rm ZO}\\sim\\omega_{\\rm G}$,\nwhere $\\omega_{\\rm G}$=1585~cm$^{-1}$ is the frequency of the Raman-active\nE$_{\\rm 2g}$ mode. Thus, the observed new peak is attributed to the 2ZO mode\nwhich becomes Raman-active following a mechanism known as Fermi resonance.\nFirst-principles calculations on vibrational and anharmonic properties of the\ngraphene/Cr interface support this scenario."
    },
    {
        "anchor": "Observation of the spin-orbit gap in bilayer graphene by one-dimensional\n  ballistic transport: We report on measurements of quantized conductance in gate-defined quantum\npoint contacts in bilayer graphene that allow the observation of subband\nsplittings due to spin-orbit coupling. The size of this splitting can be tuned\nfrom 40 to 80 $\\mu$eV by the displacement field. We assign this gate-tunable\nsubband-splitting to a gap induced by spin-orbit coupling of Kane-Mele type,\nenhanced by proximity effects due to the substrate. We show that this\nspin-orbit coupling gives rise to a complex pattern in low perpendicular\nmagnetic fields, increasing the Zeeman splitting in one valley and suppressing\nit in the other one. In addition, we observe the existence of a spin-polarized\nchannel of 6 e$^2$/h at high in-plane magnetic field and of signatures of\ninteraction effects at the crossings of spin-split subbands of opposite spins\nat finite magnetic field.",
        "positive": "A Theoretical Study on Spin-Dependent Transport of \"Ferromagnet/Carbon\n  Nanotube Encapsulating Magnetic Atoms/Ferromagnet\" Junctions with 4-Valued\n  Conductances: As a novel function of ferromagnet (FM)/spacer/FM junctions, we theoretically\ninvestigate multiple-valued (or multi-level) cell property, which is in\nprinciple realized by sensing conductances of four states recorded with\nmagnetization configurations of two FMs; (up,up), (up,down), (down,up),\n(down,down). In order to sense all the states, 4-valued conductances\ncorresponding to the respective states are necessary. We previously proposed\nthat 4-valued conductances are obtained in FM1/spin-polarized spacer (SPS)/FM2\njunctions, where FM1 and FM2 have different spin polarizations, and the spacer\ndepends on spin [J. Phys.: Condens. Matter 15, 8797 (2003)]. In this paper, an\nideal SPS is considered as a single-wall armchair carbon nanotube encapsulating\nmagnetic atoms, where the nanotube shows on-resonance or off-resonance at the\nFermi level according to its length. The magnitude of the obtained 4-valued\nconductances has an opposite order between the on-resonant nanotube and the\noff-resonant one, and this property can be understood by considering electronic\nstates of the nanotube. Also, the magnetoresistance ratio between (up,up) and\n(down,down) can be larger than the conventional one between parallel and\nanti-parallel configurations."
    },
    {
        "anchor": "Scanning probe microscopy with chemical contrast by nanoscale nuclear\n  magnetic resonance: Scanning probe microscopy is one of the most versatile windows into the\nnanoworld, providing imaging access to a variety of sample properties,\ndepending on the probe employed. Tunneling probes map electronic properties of\nsamples, magnetic and photonic probes image their magnetic and dielectric\nstructure while sharp tips probe mechanical properties like surface topography,\nfriction or stiffness. Most of these observables, however, are accessible only\nunder limited circumstances. For instance, electronic properties are measurable\nonly on conducting samples while atomic-resolution force microscopy requires\ncareful preparation of samples in ultrahigh vacuum or liquid environments.\n  Here we demonstrate a scanning probe imaging method that extends the range of\naccessible quantities to label-free imaging of chemical species operating on\narbitrary samples - including insulating materials - under ambient conditions.\nMoreover, it provides three-dimensional depth information, thus revealing\nsubsurface features. We achieve these results by recording nuclear magnetic\nresonance signals from a sample surface with a recently introduced scanning\nprobe, a single nitrogen-vacancy center in diamond. We demonstrate NMR imaging\nwith 10 nm resolution and achieve chemically specific contrast by separating\nfluorine from hydrogen rich regions.\n  Our result opens the door to scanning probe imaging of the chemical\ncomposition and atomic structure of arbitrary samples. A method with these\nabilities will find widespread application in material science even on\nbiological specimens down to the level of single macromolecules.",
        "positive": "Phase transitions on the edge of the \u03bd=5/2 Pfaffian and anti-Pfaffian\n  quantum Hall state: Starting from the edge reconstructed Pfaffian state and the anti-Pfaffian\nstate for the filling fraction $\\nu={5/2}$ fractional quantum Hall (FQH) state\nwith the filled Landau levels included, we find that interactions between\ncounterpropagating edge modes can induce phase transitions on the edge. In the\nnew `Majorana-gapped' phases, a pair of counter propagating neutral Majorana\nmodes becomes gapped. The quasiparticle tunneling exponent changes from $g=1/4$\nto $g=1/2$ for the edge reconstructed Pfaffian state, and changes from $g=1/2$\nto $g=0.55-0.75$ for the anti-Pfaffian state, in the new Majorana-gapped\nphases. The new phases are candidate states for the observed $\\nu={5/2}$ state.\nFurthermore, Majorana-gapped phases provide examples that non-trivial quantum\nphase transitions can happen on the edge of a FQH state without any change in\nbulk topological order."
    },
    {
        "anchor": "Non-reciprocal transport of Exciton-Polaritons in a non-Hermitian chain: We consider theoretically the dynamics of exciton-polaritons in a zigzag\nchain of coupled elliptical micropillars subjected to incoherent excitation.\nThe driven-dissipative nature of the system along with the naturally present\npolarization splitting inside the pillars gives rise to the non-reciprocal\ndynamics, which eventually leads to the non-Hermitian skin effect, where all\nthe modes of the system collapse to one edge. As a result, the polaritons\npropagate only in one direction along the chain, independent of the excitation\nposition, and the propagation in the opposite direction is suppressed. The\nsystem shows fair robustness against the typical disorder present in modern\nsamples. Finally, using the bistable nature of the polaritons we show that\ninformation encoded in the bistability can be transferred only one way. This\npaves the way for compact and robust feedback-free one-dimensional polariton\ntransmission channels without the need for an external magnetic field, which\nare compatible with proposals for polaritonic circuits.",
        "positive": "Development of the tunnelling gap in disordered 2D electron system with\n  magnetic field: observation of the soft-hard gap transition: Magnetic field suppression of the tunneling between disordered 2D electron\nsystems in GaAs around zero bias voltage has been studied. Magnetic field B\nnormal to the layers induces a dip in the tunneling density of states (TDOS)\ncentered precisely at the Fermi level, i.e. soft tunneling gap. The soft gap\nhas a linear form with finite TDOS diminishing with B at the Fermi level.\nDriven by magnetic field the transition soft-hard gap has been observed, i.e.\nthe TDOS vanishes in the finite energy window around Fermi level at B>13 T."
    },
    {
        "anchor": "Phonon-assisted relaxation between triplet and singlet states in a\n  self-assembled double quantum dot: We study theoretically phonon-induced spin dynamics of two electrons confined\nin a self-assembled double quantum dot. We calculate the transition rates and\ntime evolution of occupations for the spin-triplet and spin-singlet states. We\ncharacterize the relative importance of various relaxation channels as a\nfunction of the electric and magnetic fields. The simulations are based on a\nmodel combining the eight-band k.p method and configuration-interaction\napproach. We show that the electron g-factor mismatch between the Zeeman\ndoublets localized on different dots opens a relatively fast triplet-singlet\nrelaxation channel. We also demonstrate, that the relaxation near the\ntriplet-singlet anticrossing is slowed down up to several orders of magnitude\ndue to vanishing of some relaxation channels.",
        "positive": "Adiabatic and Nonadiabatic Spin-transfer Torques in Antiferromagnets: Electron transport in magnetic orders and the magnetic orders dynamics have a\nmutual dependence, which provides the key mechanisms in spin-dependent\nphenomena. Recently, antiferromagnetic orders are focused on as the magnetic\norder, where current-induced spin-transfer torques, a typical effect of\nelectron transport on the magnetic order, have been debatable mainly because of\nthe lack of an analytic derivation based on quantum field theory. Here, we\nconstruct the microscopic theory of spin-transfer torques on the slowly-varying\nstaggered magnetization in antiferromagnets with weak canting. In our theory,\nthe electron is captured by bonding/antibonding states, each of which is the\neigenstate of the system, doubly degenerates, and spatially spreads to\nsublattices because of electron hopping. The spin of the eigenstates depends on\nthe momentum in general, and a nontrivial spin-momentum locking arises for the\ncase with no site inversion symmetry, without considering any spin-orbit\ncouplings. The spin current of the eigenstates includes an anomalous component\nproportional to a kind of gauge field defined by derivatives in momentum space\nand induces the adiabatic spin-transfer torques on the magnetization.\nUnexpectedly, we find that one of the nonadiabatic torques has the same form as\nthe adiabatic spin-transfer torque, while the obtained forms for the adiabatic\nand nonadiabatic spin-transfer torques agree with the phenomenological\nderivation based on the symmetry consideration. This finding suggests that the\nconventional explanation for the spin-transfer torques in antiferromagnets\nshould be changed. Our microscopic theory provides a fundamental understanding\nof spin-related physics in antiferromagnets."
    },
    {
        "anchor": "Fluctuations of current-driven domain walls in the non-adiabatic regime: We outline a general framework to determine the effect of non-equilibrium\nfluctuations on driven collective coordinates, and apply it to a current-driven\ndomain wall in a nanocontact. In this case the collective coordinates are the\ndomain-wall position and its chirality, that give rise to momentum transfer and\nspin transfer, respectively. We determine the current-induced fluctuations\ncorresponding to these processes and show that at small frequencies they can be\nincorporated by two separate effective temperatures. As an application, the\naverage time to depin the domain wall is calculated and found to be lowered by\ncurrent-induced fluctuations. It is shown that current-induced fluctuations\nplay an important role for narrow domain walls, especially at low temperatures.",
        "positive": "Strong Rashba-Edelstein Effect-Induced Spin-Orbit Torques in Monolayer\n  Transition-Metal Dichalcogenide/Ferromagnet Bilayers: The electronic and optoelectronic properties of two dimensional materials\nhave been extensively explored in graphene and layered transition metal\ndichalcogenides (TMDs). Spintronics in these two-dimensional materials could\nprovide novel opportunities for future electronics, for example, efficient\ngeneration of spin current, which should enable the efficient manipulation of\nmagnetic elements. So far, the quantitative determination of charge current\ninduced spin current and spin-orbit torques (SOTs) on the magnetic layer\nadjacent to two-dimensional materials is still lacking. Here, we report a large\nSOT generated by current-induced spin accumulation through the Rashba-Edelstein\neffect in the composites of monolayer TMD (MoS$_2$ or WSe$_2$)/CoFeB bilayer.\nThe effective spin conductivity corresponding to the SOT turns out to be almost\ntemperature-independent. Our results suggest that the charge-spin conversion in\nthe chemical vapor deposition-grown large-scale monolayer TMDs could\npotentially lead to high energy efficiency for magnetization reversal and\nconvenient device integration for future spintronics based on two-dimensional\nmaterials."
    },
    {
        "anchor": "A comparative study of two phenomenological models of dephasing in\n  series and parallel resistors: We compare two phenomenological models of dephasing that are in use recently.\nWe show that the stochastic absorption model leads to reasonable dephasing in\nseries (double barrier) and parallel (ring) quantum resistors in presence and\nabsence of magnetic flux. For large enough dephasing it leads to Ohm's law. On\nthe other hand a random phase based statistical model that uses averaging over\nGaussian random-phases, picked up by the propagators, leads to several\ninconsistencies. This can be attributed to the failure of this model to dephase\ninterference between complementary electron waves each following time-reversed\npath of the other.",
        "positive": "Current Fluctuations and Electron-Electron Interactions in Coherent\n  Conductors: We analyze current fluctuations in mesoscopic coherent conductors in the\npresence of electron-electron interactions. In a wide range of parameters we\nobtain explicit universal dependencies of the current noise on temperature,\nvoltage and frequency. We demonstrate that Coulomb interaction decreases the\nNyquist noise. In this case the interaction correction to the noise spectrum is\ngoverned by the combination $\\sum_nT_n(T_n-1)$, where $T_n$ is the transmission\nof the $n$-th conducting mode. The effect of electron-electron interactions on\nthe shot noise is more complicated. At sufficiently large voltages we recover\ntwo different interaction corrections entering with opposite signs. The net\nresult is proportional to $\\sum_nT_n(T_n-1)(1-2T_n)$, i.e. Coulomb interaction\ndecreases the shot noise at low transmissions and increases it at high\ntransmissions."
    },
    {
        "anchor": "Magnetic proximity effect at Bi$_2$Se$_3$/EuS interface with broken\n  inversion symmetry: We investigate a magnetic proximity effect on Dirac surface states of\ntopological insulator (TI) induced by a Bi$_2$Se$_3$/EuS interface, using\ndensity-functional theory (DFT) and a low-energy effective model, motivated by\na recent experimental realization of the interface. We consider a thin\nferromagnetic insulator EuS film stacked on top of Bi$_2$Se$_3$(111) slabs of\nthree or five quintuple layers (QLs) with the magnetization of EuS normal to\nthe interface ($z$ axis), which breaks both time-reversal and inversion\nsymmetry. It is found that a charge transfer and surface relaxation makes the\nDirac cones electron-doped. For both 3 and 5 QLs, the top-surface Dirac cone\nhas an energy gap of 9 meV, while the bottom surface Dirac cone remains\ngapless. This feature is due to the short-ranged induced magnetic moment of the\nEuS film. For the 5 QLs, an additional Dirac cone with an energy gap of 2 meV\nis formed right below the bottom-surface Dirac point, while for 3 QLs, there is\nno additional Dirac cone. We also examine the spin-orbital texture of the Dirac\nsurface states with broken inversion symmetry, using DFT and the effective\nmodel. We find that the $p_z$ orbital is coupled to the $z$ component of the\nspin moment in the opposite sign to the $p_x$ and $p_y$ orbitals. The $p_z$ and\nradial $p$ orbitals are coupled to the in-plane spin texture in the opposite\nhandedness to the tangential $p$ orbital. The result obtained from the\neffective model agrees with our DFT calculations. The calculated spin-orbital\ntexture may be tested from spin-polarized angle-resolved photoemission\nspectroscopy.",
        "positive": "Contact doping, Klein tunneling, and asymmetry of shot noise in\n  suspended graphene: The inherent asymmetry of the electric transport in graphene is attributed to\nKlein tunneling across barriers defined by $\\textit{pn}$-interfaces between\npositively and negatively charged regions. By combining conductance and shot\nnoise experiments we determine the main characteristics of the tunneling\nbarrier (height and slope) in a high-quality suspended sample with Au/Cr/Au\ncontacts. We observe an asymmetric resistance $R_{\\textrm{odd}}=100-70$\n$\\Omega$ across the Dirac point of the suspended graphene at carrier density\n$|n_{\\rm G}|=0.3-4 \\cdot 10^{11}$ cm$^{-2}$, while the Fano factor displays a\nnon-monotonic asymmetry in the range $F_{\\textrm{odd}} \\sim 0.03 - 0.1$. Our\nfindings agree with analytical calculations based on the Dirac equation with a\ntrapezoidal barrier. Comparison between the model and the data yields the\nbarrier height for tunneling, an estimate of the thickness of the\n$\\textit{pn}$-interface $d < 20$ nm, and the contact region doping\ncorresponding to a Fermi level offset of $\\sim - 18$ meV. The strength of\npinning of the Fermi level under the metallic contact is characterized in terms\nof the contact capacitance $C_c=19 \\times 10^{-6}$ F/cm$^2$. Additionally, we\nshow that the gate voltage corresponding to the Dirac point is given by the\nwork function difference between the backgate material and graphene."
    },
    {
        "anchor": "Qubit-based memcapacitors and meminductors: It is shown that superconducting charge and phase qubits are quantum versions\nof memory capacitive and inductive systems, respectively. We demonstrate that\nsuch quantum memcapacitive and meminductive devices offer remarkable and rich\nresponse functionalities. In particular, when subjected to periodic input,\nqubit-based memcapacitors and meminductors exhibit unusual hysteresis curves.\nOur work not only extends the set of known memcapacitive and meminductive\nsystems to qubit-based quantum devices but also highlights their unique\nproperties potentially useful for future technological applications.",
        "positive": "Stabilized parametric Cooper-pair pumping in a linear array of coupled\n  Josephson junctions: We present an experimentally realizable stabilized charge pumping scheme in a\nlinear array of Cooper-pair boxes. The system design intrinsically protects the\npumping mechanism from severe errors, especially current reversal and\nspontaneous charge excitation. The quantum Zeno effect is implemented to\nfurther diminish pumping errors. The characteristics of this scheme are\nconsidered from the perspective of improving the current standard. Such an\nimprovement bears relevence to the closure of the so-called measurement\ntriangle (see D. Averin [Nature 434, 285 (2005)])."
    },
    {
        "anchor": "Anomalous Exciton-Condensation in Graphene Bilayers: In ordinary semiconductor bilayers, exciton condensates appear at total\nLandau level filling factor $\\nu_{T}=1$. We predict that similar states will\noccur in Bernal stacked graphene bilayers at many non-zero integer filling\nfactors. For $\\nu_{T} = -3,1$ we find that the superfluid density of the\nexciton condensate vanishes and that a finite-temperature fluctuation induced\nfirst order isotropic-smectic phase transition occurs when the layer densities\nare not balanced. These anomalous properties of bilayer graphene exciton\ncondensates are due to the degeneracy of Landau levels with $n=0$ and $n=1$\norbital character.",
        "positive": "Emergent bright excitons with Rashba spin-orbit coupling in atomic\n  monolayers: Optical properties in van der Waals heterostructures based on monolayer\ntransition-metal dichalcogenides (TMDs), are often dominated by excitonic\ntransitions. While intrinsic spin-orbit coupling (SOC) and an isotropic band\nstructure are typically studied in TMDs, in their heterostructures Rashba SOC\nand trigonal warping (TW), resulting in bands with threefold anisotropy, are\nalso present. By considering a low-energy effective Hamiltonian and\nBethe-Salpeter equation, we study the effect of Rashba SOC and TW on the band\nstructure and absorption spectra. Rashba SOC is predicted to lead to emergent\nexcitons, which are identified as an admixture between 1s and 2p symmetries. In\ncontrast, for experimentally relevant values, TW has only a negligible effect\non the absorption spectrum. These findings could guide experimental\ndemonstrations of emergent bright excitons and further studies of the proximity\neffects in van der Waals heterostructure."
    },
    {
        "anchor": "Transport and Optical Properties of Single- and Bilayer Black Phosphorus\n  with Defects: We study the electronic and optical properties of single- and bilayer black\nphosphorus with shortand long-range defects by using the tight-binding\npropagation method. Both types of defect states are localized and induce a\nstrong scattering of conduction states reducing significantly the charge\ncarrier mobility. In contrast to properties of pristine samples, the anisotropy\nof defect-induced optical excitations is suppressed due to the isotropic nature\nof the defects. We also investigate the Landau level spectrum and\nmagneto-optical conductivity, and find that the discrete Landau levels are\nsublinearly dependent on the magnetic field and energy level index, even at low\ndefect concentrations.",
        "positive": "Index theorems, generalized Hall currents and topology for gapless\n  defect fermions: We show how the index of the fermion operator from the Euclidean action can\nbe used to uncover the existence of gapless modes living on defects (such as\nedges and vortices) in topological insulators and superconductors. The 1-loop\nFeynman diagram that computes the index reveals an analog of the Quantum Hall\ncurrent flowing on and off the defect -- even in systems without conserved\ncurrents or chiral anomalies -- and makes explicit the interplay between\ntopology in momentum and coordinate space. We provide several explicit\nexamples."
    },
    {
        "anchor": "Signatures of nonlocal Cooper-pair transport and of a singlet-triplet\n  transition in the critical current of a double-quantum-dot Josephson junction: We study the critical Josephson current flowing through a double quantum dot\nweakly coupled to two superconducting leads. We use analytical as well as\nnumerical methods to investigate this setup in the limit of small and large\nbandwidth leads in all possible charging states, where we account for on-site\ninteractions exactly. Our results provide clear signatures of nonlocal\nspin-entangled pairs, which support interpretations of recent experiments\n[Deacon, R. S. et al., Nat. Commun. 6, 7446 (2015)]. In addition, we find that\nthe ground state with one electron on each quantum dot can undergo a tunable\nsinglet-triplet phase transition in the regime where the superconducting gap in\nthe leads is not too large, which gives rise to an additional new signature of\nnonlocal Cooper pair transport.",
        "positive": "Controlling the magnetism of oxygen surface vacancies in strontium\n  titanate $\\mathrm{(SrTiO_3\\!)}$ through charging: We discuss, based on first principles calculations, the possibility to tune\nthe magnetism of oxygen vacancies at the (001) surface of strontium titanate\n$(\\mathrm{SrTiO_3}\\!)$. The magnetic moment of single and clustered vacancies\nstemming from Ti-O broken bonds can be both quenched and stabilized\ncontrollably by chemical potential adjustment associated with doping the system\nwith electrons or holes. We discuss to what extent this route to magnetization\nstate control is robust against other external influences like chemical doping,\nmechanical action and electric field. Such control of vacancy state and\nmagnetization can conceivably be achieved experimentally by using local probe\ntips."
    },
    {
        "anchor": "Strain controlled valley filtering in multi-terminal graphene structures: Valley-polarized currents can be generated by local straining of\nmulti-terminal graphene devices. The pseudo-magnetic field created by the\ndeformation allows electrons from only one valley to transmit and a current of\nelectrons from a single valley is generated at the opposite side of the locally\nstrained region. We show that valley filtering is most effective with bumps of\na certain height and width. Despite the fact that the highest contribution to\nthe polarized current comes from electrons from the lowest sub-band,\ncontributions of other sub-bands are not negligible and can significantly\nenhance the output current.",
        "positive": "Life after charge noise: recent results with transmon qubits: We review the main theoretical and experimental results for the transmon, a\nsuperconducting charge qubit derived from the Cooper pair box. The increased\nratio of the Josephson to charging energy results in an exponential suppression\nof the transmon's sensitivity to 1/f charge noise. This has been observed\nexperimentally and yields homogeneous broadening, negligible pure dephasing,\nand long coherence times of up to 3 microseconds. Anharmonicity of the energy\nspectrum is required for qubit operation, and has been proven to be sufficient\nin transmon devices. Transmons have been implemented in a wide array of\nexperiments, demonstrating consistent and reproducible results in very good\nagreement with theory."
    },
    {
        "anchor": "Quantum transport in carbon nanotubes: Carbon nanotubes are a versatile material in which many aspects of condensed\nmatter physics come together. Recent discoveries, enabled by sophisticated\nfabrication, have uncovered new phenomena that completely change our\nunderstanding of transport in these devices, especially the role of the spin\nand valley degrees of freedom. This review describes the modern understanding\nof transport through nanotube devices.\n  Unlike conventional semiconductors, electrons in nanotubes have two angular\nmomentum quantum numbers, arising from spin and from valley freedom. We focus\non the interplay between the two. In single quantum dots defined in short\nlengths of nanotube, the energy levels associated with each degree of freedom,\nand the spin-orbit coupling between them, are revealed by Coulomb blockade\nspectroscopy. In double quantum dots, the combination of quantum numbers\nmodifies the selection rules of Pauli blockade. This can be exploited to read\nout spin and valley qubits, and to measure the decay of these states through\ncoupling to nuclear spins and phonons. A second unique property of carbon\nnanotubes is that the combination of valley freedom and electron-electron\ninteractions in one dimension strongly modifies their transport behaviour.\nInteraction between electrons inside and outside a quantum dot is manifested in\nSU(4) Kondo behavior and level renormalization. Interaction within a dot leads\nto Wigner molecules and more complex correlated states.\n  This review takes an experimental perspective informed by recent advances in\ntheory. As well as the well-understood overall picture, we also state clearly\nopen questions for the field. These advances position nanotubes as a leading\nsystem for the study of spin and valley physics in one dimension where\nelectronic disorder and hyperfine interaction can both be reduced to a very low\nlevel.",
        "positive": "Enhanced transport length of spin-helical Dirac fermions in disordered\n  3D topological insulators: The transport length $l_\\textrm{tr}$ and the mean free path $l_\\textrm{e}$\nare experimentally determined for bulk and surface states in a Bi$_2$Se$_3$\nnanoribbon by quantum transport and transconductance measurements. We show that\nthe anisotropic scattering of spin-helical Dirac fermions results in a strong\nenhancement of $l_\\textrm{tr}$, which confirms theoretical predictions\n\\cite{Culcer2010}. Despite strong disorder ($l_\\textrm{e}\\approx30$~nm), our\nresult further points to the long-range nature of the scattering potential,\ngiving a large ratio $l_\\textrm{tr}/l_\\textrm{e}\\approx8$ that is likely\nlimited by a finite bulk/surface coupling. This suggests that the spin-flip\nlength could reach the micron size in disordered 3D topological insulator\nnanostructures with a reduced bulk doping, even if due to charge compensation."
    },
    {
        "anchor": "Charging of colloidal nanoplatelets: effect of Coulomb repulsion on spin\n  and optoelectronic properties: Colloidal semiconductor nanoplatelets combine weak lateral confinement with\nstrong Coulomb interactions, enhanced by dielectric confinement. When the\nplatelets are charged with carriers of the same sign, this results in severe\nCoulomb repulsions which shape the electronic structure. To illustrate this\npoint, the shell filling of type-I (CdSe/CdS) and type-II (CdSe/CdTe)\ncore/crown nanoplatelets with up to 4 electrons or holes is investigated\ntheoretically. We find that Coulomb repulsions enable addition energies\nexceeding room temperature thermal energy and promote the occupation of\nhigh-spin states. For charged excitons and biexcitons in CdSe/CdTe\nnanoplatelets, the repulsions further give rise to multi-peaked emission\nspectra with widely tunable (over 100 meV) energy, and a transition from\ntype-II to quasi-type-II band profile as the number of electrons confined in\nthe core increases. We conclude that the number of excess carriers injected in\nnanoplatelets is a versatile degree of freedom to modulate their magnetic and\noptoelectronic properties.",
        "positive": "Optical and transport properties of short period InAs/GaAs superlattices\n  near quantum dot formation: We have investigated the optical and transport properties of MBE grown\nshort-period superlattices of InAs/GaAs with different numbers of periods (3 <=\nN <= 24) and a total thickness 14 nm. Bandstructure calculations show that\nthese superlattices represent a quantum well with average composition\nIn_0.16Ga_0.84As. The electron wave functions are only slightly modulated by\nthe superlattice potential as compared to a single quantum well with the same\ncomposition, which was grown as a reference sample. The photoluminescence, the\nresistance, the Shubnikov-de Haas effect and the Hall effect have been measured\nas a function of the InAs layer thickness Q in the range 0.33 <= Q <= 2.7\nmonolayers (ML). The electron densities range from 6.8 to 11.5x10^11 cm^-2 for\nQ <= 2.0 ML. The photoluminescence and magnetotransport data show that only one\nsubband is occupied. When Q >= 2.7 ML quantum dots are formed and the metallic\ntype of conductivity changes to variable range hopping conductivity."
    },
    {
        "anchor": "Dirac model of electronic transport in graphene antidot barriers: In order to use graphene for semiconductor applications, such as transistors\nwith high on/off ratios, a band gap must be introduced into this otherwise\nsemimetallic material. A promising method of achieving a band gap is by\nintroducing nanoscale perforations (antidots) in a periodic pattern, known as a\ngraphene antidot lattice (GAL). A graphene antidot barrier (GAB) can be made by\nintroducing a 1D GAL strip in an otherwise pristine sheet of graphene. In this\npaper, we will use the Dirac equation (DE) with a spatially varying mass term\nto calculate the electronic transport through such structures. Our approach is\nmuch more general than previous attempts to use the Dirac equation to calculate\nscattering of Dirac electrons on antidots. The advantage of using the DE is\nthat the computational time is scale invariant and our method may therefore be\nused to calculate properties of arbitrarily large structures. We show that the\nresults of our Dirac model are in quantitative agreement with tight-binding for\nhexagonal antidots with armchair edges. Furthermore, for a wide range of\nstructures, we verify that a relatively narrow GAB, with only a few antidots in\nthe unit cell, is sufficient to give rise to a transport gap.",
        "positive": "Revealing the internal spin dynamics in a double quantum dot by periodic\n  voltage modulation: The paper proposes the method to analyze the internal dynamics of nanoscopic\nsystems by periodic modulation of the electrochemical potentials of the\nattached leads and measuring the time-averaged current. The idea is presented\nusing the example of the a double quantum dot coupled to one nonmagnetic and\none spin-polarized lead. The current flowing through the molecule is shown to\ndepend on both the frequency of the modulation and the exchange coupling\nbetween the electrons occupying the molecule. In particular, one can observe a\npronounced oscillatory behavior of the current-frequency dependence, which\nreveals the coherent oscillations between the spin states of the system."
    },
    {
        "anchor": "Protected pseudohelical edge states in proximity graphene ribbons and\n  flakes: We investigate topological properties of models that describe graphene on\nrealistic substrates which induce proximity spin-orbit coupling in graphene. A\n$\\mathbb{Z}_2$ phase diagram is calculated for the parameter space of\n(generally different) intrinsic spin-orbit coupling on the two graphene\nsublattices, in the presence of Rashba coupling. The most fascinating case is\nthat of staggered intrinsic spin-orbit coupling which, despite being\ntopologically trivial, $\\mathbb{Z}_2 = 0$, does exhibit edge states protected\nagainst time-reversal scattering for zigzag ribbons as wide as micrometers. We\ncall these states pseudohelical as their helicity is locked to the sublattice.\nThe spin character and robustness of the pseudohelical modes is best exhibited\non a finite flake, which shows that the edge states have zero $g$-factor, carry\na finite spin current in the crossection of the flake, and exhibit spin-flip\nreflectionless tunneling at the armchair edges.",
        "positive": "Effect of cosmic string on spin dynamics: In the present paper, we have investigated the role of cosmic string on spin\ncurrent and Hall electric field. Due to the background cosmic string, the\nmodified electric field of the system generates renormalized spin orbit\ncoupling, which induces a modified non-Abelian gauge field. The defect causes a\nchange in the AB and AC phases appearing due to the modified electromagnetic\nfield. In addition, for a time varying electric field we perform explicit\nanalytic calculations to derive the exact form of spin electric field and spin\ncurrent, which is defect parameter dependent and of oscillating type.\nFurthermore, in an asymmetric crystal within the Drude model approach we\ninvestigate the dependence of the cosmic string parameters on cosmic string\ninduced Hall electric field."
    },
    {
        "anchor": "Microscopic theory of absorption and emission in nanostructured solar\n  cells: Beyond the generalized Planck formula: Absorption and emission in inorganic bipolar solar cells based on low\ndimensional structures exhibiting the effects of quantum confinement is\ninvestigated in the framework of a comprehensive microscopic theory of the\noptical and electronic degrees of freedom of the photovoltaic system. In a\nquantum-statistical treatment based on non-equilibrium Green's functions, the\noptical transition rates are related to the conservation of electronic\ncurrents, providing a quantum version of the balance equations describing the\noperation of a photovoltaic device. The generalized Planck law used for the\ndetermination of emission from an excited semiconductor in quasi-equilibrium is\nreplaced by an expression of extended validity, where no assumptions on the\ndistribution of electrons and photons are made. The theory is illustrated by\nthe numerical simulation of single quantum well diodes at the radiative limit.",
        "positive": "Universality in the Crossover between Edge Channel and Bulk Transport in\n  the Quantum Hall Regime: We present a new theoretical approach for the integer quantum Hall effect,\nwhich is able to describe the inter-plateau transitions as well as the\ntransition to the Hall insulator. We find two regimes (metallic and insulator\nlike) of the top Landau level, in which the dissipative bulk current appears in\ndifferent directions. The regimes are separated by a temperature invariant\npoint."
    },
    {
        "anchor": "Enhanced Majorana bound states in magnetic chains on superconducting\n  topological insulator edges: The most promising mechanisms for the formation of Majorana bound states\n(MBSs) in condensed matter systems involve one-dimensional systems (such as\nsemiconductor nanowires, magnetic chains, and quantum spin Hall insulator\n(QSHI) edges) proximitized to superconducting materials. The choice between\neach of these options involves trade-offs between several factors such as\nreproducibility of results, system tunability, and robustness of the resulting\nMBS. In this article, we propose that a combination of two of these systems,\nnamely a magnetic chain deposited on a QSHI edge in contact with a\nsuperconducting surface, offers a better choice of tunability and MBS\nrobustness compared to magnetic chain deposited on bulk. We study how the QSHI\nedge interacts with the magnetic chain, and see how the topological phase is\naffected by edge proximity. We show that MBSs near the edge can be realized\nwith lower chemical potential and Zeeman field than the ones inside the bulk,\nindependently of the chain's magnetic order (ferromagnetic or spiral order).\nDifferent magnetic orderings in the chain modify the overall phase diagram,\neven suppressing the boundless topological phase found in the bulk for chains\nlocated at the QSHI edge. Moreover, we quantify the \"quality\" of MBSs by\ncalculating the Majorana Polarization (MP) for different configurations. For\nchains located at the edge, the MP is close to its maximum value already for\nshort chains. For chains located away from the edge, longer chains are needed\nto attain the same quality as chains located at the edge. The MP also\noscillates in phase with the in-gap states, which is relatively unexpected as\npeaks in the energy spectrum corresponds to stronger overlap of MBSs.",
        "positive": "Nanoantenna-enhanced ultrafast nonlinear spectroscopy of a single gold\n  nanoparticle: Optical nanoantennas are a novel tool to investigate previously unattainable\ndimensions in the nanocosmos. Just like their radio-frequency equivalents,\nnanoantennas enhance the light-matter interaction in their feed gap. Antenna\nenhancement of small signals promises to open a new regime in linear and\nnonlinear spectroscopy on the nanoscale. Without antennas especially the\nnonlinear spectroscopy of single nanoobjects is very demanding. Here, we\npresent for the first time antenna-enhanced ultrafast nonlinear optical\nspectroscopy. In particular, we utilize the antenna to determine the nonlinear\ntransient absorption signal of a single gold nanoparticle caused by mechanical\nbreathing oscillations. We increase the signal amplitude by an order of\nmagnitude which is in good agreement with our analytical and numerical models.\nOur method will find applications in linear and nonlinear spectroscopy of\nnanoobjects, ranging from single protein binding events via nonlinear tensor\nelements to the limits of continuum mechanics."
    },
    {
        "anchor": "Quantum entanglement of electrons in a biased 1D two-probe device: Electronic quantum entanglement between the central chain and the two\nelectrodes in an infinite one-dimensional two-probe device system is studied.\nThe entanglement entropy is calculated employing the nonequilibrium Green's\nfunction method in the tight-binding model based on the relation between the\ncorrelation matrix and the von Neumann entropy. By extending the entropy to\nnonequilibrium cases, we have studied the scaling behavior when a voltage bias\nis applied between the two electrodes. The entropy usually decreases with the\nbias and may jump up when a quasi-state in the chain aligns in energy with the\nband edges in the electrodes. Odd-even effect is observed due to the symmetry\nof the chain.",
        "positive": "Unusual temperature evolution of band structure of Bi(111) studied by\n  angle-resolved photoemission spectroscopy and density functional theory: We have performed angle-resolved photoemission spectroscopy of Bi(111) thin\nfilms grown on Si(111), and investigated the evolution of band structure with\ntemperature. We revealed an unexpectedly large temperature variation of the\nenergy dispersion for the Rashba-split surface state and the quantum-well\nstates, as seen in the highly momentum-dependent energy shift as large as 0.1\neV. A comparison of the band dispersion between experiment and first-principles\nband-structure calculations suggests that the interlayer spacing at the topmost\nBi bilayer expands upon temperature increase. The present study provides a new\npathway for investigating the interplay between lattice and electronic states\nthrough the temperature dependence of band structure."
    },
    {
        "anchor": "Survival of sharp $n=0$ Landau levels in massive tilted Dirac fermions:\n  Protection by generalized chiral operator: Anomalously sharp (delta-function-like) $n=0$ Landau level in the presence of\ndisorder is usually considered to be a manifestation of the massless Dirac\nfermions in magnetic fields. This property persists even when the Dirac cone is\ntilted, which has been shown by Kawarabayashi et al. [Phys. Rev. B {\\bf 83},\n153414 (2011)] to be a consequence of a \"generalized chiral symmetry\". Here we\npose a question whether this property will be washed out when the tilted Dirac\nfermion becomes massive. Surprisingly, the levels persist to be\ndelta-function-like, although the mass term that splits $n=0$ Landau levels may\nseem to degrade the anomalous sharpness. This has been shown both numerically\nfor a tight-binding model, and analytically in terms of the Aharonov-Casher\nargument extended to the massive tilted Dirac fermions. A key observation is\nthat, while the generalized chiral symmetry is broken by the mass term, the\n$n=0$ Landau level remains to accommodate eigenstates of the generalized chiral\noperator, resulting in the robustness against chiral-symmetric disorders.\nMathematically, the conventional and generalized chiral operators are related\nwith each other via a non-unitary transformation, with which the split,\nnonzero-energy $n=0$ wave functions of the massive system are just\ngauge-transformed zero-mode wave functions of the massless system. A message is\nthat the chiral symmetry, rather than a simpler notion of the sublattice\nsymmetry, is essential for the robustness of the $n=0$ Landau level.",
        "positive": "Quantum transport through a coupled non-linear exciton-phonon system: Wavepacket transport across a nonlinear region is studied numerically at zero\nand finite temperatures. In contrary to the zero temperature case which\ndemonstrates ballistic transport, finite temperature lattice vibrations\nsuppresses the transport drastically. The interface between the linear and the\nnonlinear chain plays the role of a high barrier at finite temperature when\nanharmonicity factor is small compared to the typical inverse cubic interatomic\ndistance. Inverse participation ratio of the central region shows that for\nsmall anharmonicity and finite temperatures lattice vibrations give rise to\nself-trapping in the nonlinear chain which lasts for considerable times with a\nsubdiffusive leakage of the wavepacket, almost equally, to both leads. The\nscenario changes when the anharmonicity becomes comparable with average inverse\ncubic interatomic distances as the lattice dynamics gives a profound boost to\nthe transmission and starts to be almost transparent for the incoming pulse."
    },
    {
        "anchor": "Chiral interface states in graphene $p$-$n$ junctions: We present a theoretical analysis of unidirectional interface states which\nform near $p$-$n$ junctions in a graphene monolayer subject to a homogeneous\nmagnetic field. The semiclassical limit of these states corresponds to\ntrajectories propagating along the $p$-$n$ interface by a combined\nskipping-snaking motion. Studying the two-dimensional Dirac equation with a\nmagnetic field and an electrostatic potential step, we provide and discuss the\nexact and essentially analytical solution of the quantum-mechanical\neigenproblem for both a straight and a circularly shaped junction. The spectrum\nconsists of localized Landau-like and unidirectional snaking-skipping interface\nstates, where we always find at least one chiral interface state. For a\nstraight junction and at energies near the Dirac point, when increasing the\npotential step height, the group velocity of this state interpolates in an\noscillatory manner between the classical drift velocity in a crossed\nelectromagnetic field and the semiclassical value expected for a purely snaking\nmotion. Away from the Dirac point, chiral interface states instead resemble the\nconventional skipping (edge-type) motion found also in the corresponding\nSchr\\\"odinger case. We also investigate the circular geometry, where chiral\ninterface states are predicted to induce sizeable equilibrium ring currents.",
        "positive": "Spin photocurrents and circular photon drag effect in (110)-grown\n  quantum well structures: We report on the study of spin photocurrents in (110)-grown quantum well\nstructures. Investigated effects comprise the circular photogalvanic effect and\nso far not observed circular photon drag effect. The experimental data can be\ndescribed by an analytical expression derived from a phenomenological theory. A\nmicroscopic model of the circular photon drag effect is developed demonstrating\nthat the generated current has spin dependent origin."
    },
    {
        "anchor": "Computational Exploration of the Nanogold Energy Landscape: We use density functional theory to quantify finite size and shape effects\nfor gold nanoclusters. We concentrate on the computation of binding energy as a\nfunction of bond length for icosahedral and cuboctohedral clusters. We find\nthat the cuboctoheral gold clusters have lower energy for 13 atoms. For 55\natoms we find that the icosahedral gold clusters have lower binding energy. We\nalso introduce a one parameter family of geometries that interpolate between\nthe icosahedral and cuboctohedral clusters that is parametrized by an angle\nvariable. We determine the binding energy dependence on shape as a function of\nthe angle variable for 13 and 55 atom clusters with a minimum at the\ncuboctohedral point and icosahedral point respectively. We also compute the\nbinding energy for the 147 atom gold nanocluster and show that the binding\nenergy of the icosahedral cluster is lower than the 147 atom cuboctohedral gold\ncluster. We also compute the binding energy of the $Au_{55}O_2$ molecule with\npossible applications to catalysis.",
        "positive": "Counting Statistics of Single Electron Transport in Bilayer Graphene\n  Quantum Dots: We measure telegraph noise of current fluctuations in an electrostatically\ndefined quantum dot in bilayer graphene by real-time detection of single\nelectron tunneling with a capacitively coupled neighboring quantum dot.\nSuppression of the second and third cumulant (related to shot noise) in a\ntunable graphene quantum dot is demonstrated experimentally. With this method\nwe demonstrate the ability to measure very low current and noise levels.\nFurthermore, we use this method to investigate the first spin excited state, an\nessential prerequisite to measure spin relaxation."
    },
    {
        "anchor": "Interplay between morphological and shielding effects in field emission\n  via Schwarz-Christoffel transformation: It is well known that sufficiently strong electrostatic fields are able to\nchange the morphology of Large Area Field Emitters (LAFEs). This phenomenon\naffects the electrostatic interactions between adjacent sites on a LAFE during\nfield emission and may lead to several consequences, such as: the emitter's\ndegradation, diffusion of absorbed particles on the emitter's surface,\ndeflection due to electrostatic forces and mechanical stress. These\nconsequences are undesirable for technological applications, since they may\nsignificantly affect the macroscopic current density on the LAFE. Despite the\ntechnological importance, these processes are not completely understood yet.\nMoreover, the electrostatic effects due to the proximity between emitters on a\nLAFE may compete with the morphological ones. The balance between these effects\nmay lead to a non trivial behavior in the apex-Field Enhancement Factor (FEF).\nThe present work intends to study the interplay between proximity and\nmorphological effects by studying a model amenable for an analytical treatment.\nIn order to do that, a conducting system under an external electrostatic field,\nwith a profile limited by two mirror-reflected triangular protrusions on an\ninfinite line, is considered. The FEF near the apex of each emitter is obtained\nas a function of their shape and the distance between them via a\nSchwarz-Christoffel transformation. Our results suggest that a tradeoff between\nmorphological and proximity effects on a LAFE may provide an explanation for\nthe observed reduction of the local FEF and its variation at small distances\nbetween the emitter sites.",
        "positive": "Thermally-Assisted Spin-Transfer Torque Magnetization Reversal of\n  Uniaxial Nanomagnets in Energy Space: The asymptotic behavior of switching time as a function of current for a\nuniaxial macrospin under the effects of both spin-torque and thermal noise is\nexplored analytically by focusing on its diffusive energy space dynamics. The\nscaling dependence ($I\\rightarrow 0$, $<\\tau\\propto\\exp(-\\xi(1-I)^2)$) is shown\nto confirm recent literature results. The analysis shows the mean switching\ntime to be functionally independent of the angle between the spin current and\nmagnet's uniaxial axes. These results have important implications for modeling\nthe energetics of thermally assisted magnetization reversal of spin transfer\nmagnetic random access memory bit cells."
    },
    {
        "anchor": "Quantum transport through a deformable molecular transistor: The linear transport properties of a model molecular transistor with\nelectron-electron and electron-phonon interactions were investigated\nanalytically and numerically. The model takes into account phonon modulation of\nthe electronic energy levels and of the tunnelling barrier between the molecule\nand the electrodes. When both effects are present they lead to asymmetries in\nthe dependence of the conductance on gate voltage. The Kondo effect is observed\nin the presence of electron-phonon interactions. There are important\nqualitative differences between the cases of weak and strong coupling. In the\nfirst case the standard Kondo effect driven by spin fluctuations occurs. In the\nsecond case, it is driven by charge fluctuations. The Fermi-liquid relation\nbetween the spectral density of the molecule and its charge is altered by\nelectron-phonon interactions. Remarkably, the relation between the\nzero-temperature conductance and the charge remains unchanged. Therefore, there\nis perfect transmission in all regimes whenever the average number of electrons\nin the molecule is an odd integer.",
        "positive": "Mixing of surface and bulk electronic states at a graphite-hexagonal\n  boron nitride interface: Van der Waals assembly enables exquisite design of electronic states in\ntwo-dimensional (2D) materials, often by superimposing a long-wavelength\nperiodic potential on a crystal lattice using moir\\'e superlattices. Here we\nshow that electronic states in three-dimensional (3D) crystals such as graphite\ncan also be tuned by the superlattice potential arising at the interface with\nanother crystal, namely, crystallographically aligned hexagonal boron nitride.\nSuch alignment is found to result in a multitude of Lifshitz transitions and\nBrown-Zak oscillations for near-surface 2D states whereas, in high magnetic\nfields, fractal states of Hofstadter's butterfly extend deep into graphite's\nbulk. Our work shows a venue to control 3D spectra by using the approach of 2D\ntwistronics."
    },
    {
        "anchor": "Quantum charge transport in Mo$_{6}$S$_{3}$I$_{6}$ molecular wire\n  circuits: Charge transport measurements on flexible Mo$_{6}$S$_{3}$I$_{6}$ (MoSI)\nnanowires with different diameters in highly imperfect 2-terminal circuits\nreveal systematic power law behaviour of the conductivity $\\sigma(T,V)$ as a\nfunction of temperature and voltage. On the basis of measurements on a number\nof circuits we conclude that the behaviour in \\emph{thin} wires can be most\nconvincingly described by tunneling through Tomonaga-Luttinger liquid (TLL)\nsegments of MoSI wire, which is in some cases modified by environmental Coulomb\nblockade (ECB). The latter are proposed to arise from deformations or\nimperfections of the MoSI wires, which - in combination with their recognitive\nterminal sulfur-based connectivity properties - might be useful for creating\nsub-nanometer scale interconnects as well as non-linear elements for molecular\nelectronics.",
        "positive": "Topological swing in Bloch oscillations: We report new oscillations of wavepackets in quantum walks subjected to\nelectric fields, that decorate the usual Bloch-Zener oscillations of\ninsulators. The number of turning points (or sub-oscillations) within one Bloch\nperiod of these oscillations is found to be governed by the winding of the\nquasienergy spectrum. Thus, this provides a new physical manifestation of a\ntopological property of periodically driven systems that can be probed\nexperimentally. Our model, based on an oriented scattering network, is readily\nimplementable in photonic and cold atomic setups."
    },
    {
        "anchor": "Thermoelectric properties of a quantum dot coupled to magnetic leads by\n  Rashba spin-orbit interaction: We consider a single-level quantum dot coupled to two leads which are\nferromagnetic in general. Apart from tunneling processes conserving electron\nspin, we also include processes associated with spin-flip of tunneling\nelectrons, which appear due to Rashba spin-orbit coupling. Charge and heat\ncurrents are calculated within the non-equilibrium Green's function technique.\nWhen the electrodes are half-metallic (fully spin polarized), the Rashba\nspin-orbit coupling leads to Fano-like interference effects, which result in an\nenhanced thermoelectric response. It is also shown that such a system can\noperate as efficient heat engine. Furthermore, the interplay of Rashba\nspin-orbit coupling and Zeeman splitting due to an external magnetic field is\nshown to allow control over such parameters of the heat engine as the power and\nefficiency.",
        "positive": "Transport through strongly correlated triple quantum dot: Strong electron correlations are discussed for the three capacitively coupled\nquantum dots, each of which is connected to a separate pair of electrodes. The\nfinite-$U$ mean field slave boson approach is used. The analysis is carried out\nfor both repulsive and attractive intra- and inter-dot interactions. Depending\non the ratio and the sign of interaction parameters and occupation, either\ncharge ordered states or different spin, spin-charge and charge Kondo\nresonances arise."
    },
    {
        "anchor": "Chiral Anomaly and Second Harmonic Generation in Weyl Semimetals: We study second harmonic generation in centrosymmetric Weyl semimetal with\nbroken time reversal symmetry. We calculate electric current density at the\ndouble frequency of the propagating electromagnetic field in the presence of\napplied constant magnetic field, using the method of kinetic equation for\nelectron distribution function. It is shown that the chiral anomaly\ncontribution to second harmonic generation in the lowest order is linearly\nproportional to the applied magnetic field. The limit when the chiral anomaly\ndominates over the Lorentz-type contribution to second harmonic generation is\ndiscussed.",
        "positive": "Universal Spin Hall Conductance Fluctuations in Chaotic Dirac Quantum\n  Dots: We present complete analytical and numerical results that demonstrate the\nanomalous universal fluctuations of the spin-Hall conductance in chiral\nmaterials such as graphene and topological insulators. We investigated both the\ncorresponding fluctuations, the Universal Fractionated and the Universal\nQuantized, and also the open channels orbital number crossover between the two\nregimes. In particular, we show that the Wigner-Dyson symmetries does not\nproperly describe such conductances and the preponderant role of the chiral\nclasses on the Dirac quantum dots. The results are analytical and solve\noutstanding issues."
    },
    {
        "anchor": "Quantum Anomalous Hall Effect in Single-layer and Bilayer Graphene: The quantum anomalous Hall effect can occur in single and few layer graphene\nsystems that have both exchange fields and spin-orbit coupling. In this paper,\nwe present a study of the quantum anomalous Hall effect in single-layer and\ngated bilayer graphene systems with Rashba spin-orbit coupling. We compute\nBerry curvatures at each valley point and find that for single-layer graphene\nthe Hall conductivity is quantized at $\\sigma_{xy} = 2e^2/h$, with each valley\ncontributing a unit conductance and a corresponding chiral edge state. In\nbilayer graphene, we find that the quantized anomalous Hall conductivity is\ntwice that of the single-layer case when the gate voltage $U$ is smaller than\nthe exchange field $M$, and zero otherwise. Although the Chern number vanishes\nwhen $U > M$, the system still exhibits a quantized valley Hall effect, with\nthe edge states in opposite valleys propagating in opposite directions. The\npossibility of tuning between different topological states with an external\ngate voltage suggests possible graphene-based spintronics applications.",
        "positive": "An IR Photodetector Using an Optically Cooled Micromirror as a Light\n  Pressure Sensor: We consider mid-infrared (5 to 25 micrometers), optically cooled detectors\nbased on a microcantilever sensor of the radiation pressure. A significant\nenhancement of sensitivity is achieved due the combination of low effective\ntemperature (10 K), non-absorption detection, and a high quality optical\nmicrocavity. Applications to spectrometry are examined. It is shown that an\noptically cooled radiation pressure sensor potentially has a sensitivity an\norder of magnitude better than the best conventional uncooled detectors."
    },
    {
        "anchor": "Molecular self-organization: Predicting the pattern diversity and lowest\n  energy state of competing ordering motifs: Self-organized monolayers of highly flexible \\Frechet dendrons were deposited\non graphite surfaces by solution casting. Scanning tunneling microscopy (STM)\nreveals an unprecedented variety of patterns with up to seven stable\nhierarchical ordering motifs serving as a versatile model system. The essential\nmolecular properties determined by molecular mechanics simulations are\ncondensed to a coarse grained interaction site model of various chain\nconfigurations. In a Monte Carlo approach with random starting configurations\nthe experimental pattern diversity can be reproduced in all facets of the local\nand global ordering. Based on an energy analysis of the Monte Carlo and\nmolecular mechanics modeling the thermodynamically most stable pattern is\npredicted coinciding with the pattern, which dominates in the STM images after\nseveral hours or upon moderate heating.",
        "positive": "Tailoring the magnetodynamic properties of nanomagnets using\n  magnetocrystalline and shape anisotropies: Magnetodynamical properties of nanomagnets are affected by the demagnetizing\nfields created by the same nanoelements. In addition, magnetocrystalline\nanisotropy produces an effective field that also contributes to the spin\ndynamics. In this article we show how the dimensions of magnetic elements can\nbe used to balance crystalline and shape anisotropies, and that this can be\nused to tailor the magnetodynamic properties. We study ferromagnetic ellipses\npatterned from a 10 nm thick epitaxial Fe film with dimensions ranging from 50\nx 150 nm to 150 x 450 nm. The study combines ferromagnetic resonance (FMR)\nspectroscopy with analytical calculations and micromagnetic simulations, and\nproves that the dynamical properties can be effectively controlled by changing\nthe size of the nanomagnets. We also show how edge defects in the samples\ninfluence the magnetization dynamics. Dynamical edge modes localized along the\nsample edges are strongly influenced by edge defects, and this needs to be\ntaken into account in understanding the full FMR spectrum"
    },
    {
        "anchor": "Strain-dependent exciton diffusion in transition metal dichalcogenides: Monolayers of transition metal dichalcogenides (TMDs) have a remarkable\nexcitonic landscape with deeply bound bright and dark exciton states. Their\nproperties are strongly affected by lattice distortions that can be created in\na controlled way via strain. Here, we perform a joint theory-experiment study\ninvestigating exciton diffusion in strained tungsten disulfide (WS$_2$)\nmonolayers. We reveal a non-trivial and non-monotonic influence of strain.\nLattice deformations give rise to different energy shifts for bright and dark\nexcitons changing the excitonic landscape, the efficiency of intervalley\nscattering channels, and the weight of single exciton species to the overall\nexciton diffusion. We predict a minimal diffusion coefficient in unstrained\nWS$_2$ followed by a steep speed-up by a factor of 3 for tensile biaxial strain\nat about 0.6\\% strain - in excellent agreement with our experiments. The\nobtained microscopic insights on the impact of strain on exciton diffusion are\napplicable to a broad class of multi-valley 2D materials.",
        "positive": "Conductivity of Coulomb interacting massless Dirac particles in\n  graphene: Regularization-dependent parameters and symmetry constraints: We compute the Coulomb correction $\\mathcal{C}$ to the a. c. conductivity of\ninteracting massless Dirac particles in graphene in the collisionless limit\nusing the polarization tensor approach in a regularization independent\nframework. Arbitrary parameters stemming from differences between\nlogarithmically divergent integrals are fixed on physical grounds exploiting\nonly spatial $O(2)$ rotational invariance of the model which amounts to\ntransversality of the polarization tensor. Consequently $\\mathcal{C}$ is\nunequivocally determined to be $(19- 6\\pi)/12$ within this effective model. We\ncompare our result with explicit regularizations and discuss the origin of\nothers results for $\\mathcal{C}$ found in the literature."
    },
    {
        "anchor": "Control of the Exciton Transfer in Quantum Dots by the Stark Effect: Resonant transfer of energy between excited states in a system of two\nsemiconductor quantum dots is studied theoretically. The model Hamiltonian has\nbeen formulated, which allowed describe the impact on the dynamics of the\nresonant laser pulse, the Coulomb interaction, the static Stark effect, and the\nrelaxation of the exciton states. Examples of calculations for efficiency of\nthe energy transfer under different excitation conditions are presented. The\ncontrol of the process by the level shift in a constant electric field is\ndemonstrated.",
        "positive": "Dependence of the intrinsic spin Hall effect on spin-orbit interaction\n  character: We report on a comparative numerical study of the spin Hall conductivity in\ntwo-dimensions for three different spin-orbit interaction models; the standard\nk-linear Rashba model, the k-cubic Rashba model that describes two-dimensional\nhole systems, and a modified k-linear Rashba model in which the spin-orbit\ncoupling strength is energy dependent. Numerical finite-size Kubo formula\nresults indicate that the spin Hall conductivity of the k-linear Rashba model\nvanishes for frequency $\\omega$ much smaller than the scattering rate\n$\\tau^{-1}$, with order one relative fluctuations surviving out to large system\nsizes. For the k-cubic Rashba model case, the spin Hall conductivity does not\ndepend noticeably on $\\omega \\tau$ and is finite in the {\\em dc} limit, in\nagreement with experiment. For the modified k-linear Rashba model the spin Hall\nconductivity is noticeably $\\omega \\tau$ dependent but approaches a finite\nvalue in the {\\em dc} limit. We discuss these results in the light of a\nspectral decomposition of the spin Hall conductivity and associated sum rules,\nand in relation to a proposed separation of the spin Hall conductivity into\nskew-scattering, intrinsic, and interband vertex correction contributions."
    },
    {
        "anchor": "Optical flux pump in the quantum Hall regime: A seminal gedankenexperiment by Laughlin describes the charge transport in\nquantum Hall systems via the pumping of flux. Here, we propose an optical\nscheme which probes and manipulates quantum Hall systems in a similar way: When\nlight containing orbital angular momentum interacts with electronic Landau\nlevels, it acts as a flux pump which radially moves the electrons through the\nsample. We investigate this effect for a graphene system with Corbino geometry,\nand calculate the radial current in the absence of any electric potential bias.\nRemarkably, the current is robust against the disorder which is consistent with\nthe lattice symmetry, and in the weak excitation limit, the current shows a\npower-law scaling with intensity characterized by the novel exponent 2/3.",
        "positive": "Molecular collapse in graphene: sublattice symmetry effect: Atomic collapse can be observed in graphene because of its large \"effective\"\nfine structure constant, which enables this phenomenon to occur for an impurity\ncharge as low as $Z_c\\sim 1-2$. Here, we investigate the effect of the\nsublattice symmetry on molecular collapse in two spatially separated charge\ntunable vacancies, that are located on the same (A-A type) or different (A-B\ntype) sublattices. We find that the broken sublattice symmetry: (1) does not\naffect the location of the main bonding and anti-bonding molecular collapse\npeaks, (2) but shifts the position of the satellite peaks, because they are a\nconsequence of the breaking of the local sublattice symmetry, and (3) there are\nvacancy characteristic collapse peaks that only occur for A-B type vacancies,\nwhich can be employed to distinguish them experimentally from the A-A type. As\nthe charge, energy, and separation distance increase, the additional collapse\nfeatures merge with the main molecular collapse peaks. We show that the spatial\ndistribution around the vacancy site of the collapse states allows us to\ndifferentiate the molecular from the frustrated collapse."
    },
    {
        "anchor": "Band Representations and Topological Quantum Chemistry: In this article, we provide a pedagogical review of the theory of topological\nquantum chemistry and topological crystalline insulators. We begin with an\noverview of the properties of crystal symmetry groups in position and momentum\nspace. Next, we introduce the concept of a band representation, which\nquantifies the symmetry of topologically trivial band structures. By combining\nband representations with symmetry constraints on the connectivity of bands in\nmomentum space, we show how topologically nontrivial bands can be catalogued\nand classified. We present several examples of new topological phases\ndiscovered using this paradigm, and conclude with an outlook towards future\ndevelopments.",
        "positive": "The structure of suspended graphene sheets: The recent discovery of graphene has sparked significant interest, which has\nso far been focused on the peculiar electronic structure of this material, in\nwhich charge carriers mimic massless relativistic particle. However, the\nstructure of graphene - a single layer of carbon atoms densely packed in a\nhoneycomb crystal lattice - is also puzzling. On the one hand, graphene appears\nto be a strictly two-dimensional (2D) material and exhibits such a high crystal\nquality that electrons can travel submicron distances without scattering. On\nthe other hand, perfect 2D crystals cannot exist in the free state, according\nto both theory and experiment. This is often reconciled by the fact that all\ngraphene structures studied so far were an integral part of larger 3D\nstructures, either supported by a bulk substrate or embedded in a 3D matrix.\nHere we report individual graphene sheets freely suspended on a microfabricated\nscaffold in vacuum or air. These membranes are only one atom thick and still\ndisplay a long-range crystalline order. However, our studies by transmission\nelectron microscopy (TEM) have revealed that suspended graphene sheets are not\nperfectly flat but exhibit intrinsic microscopic roughening such that the\nsurface normal varies by several degrees and out-of-plane deformations reach 1\nnm. The atomically-thin single-crystal membranes offer an ample scope for\nfundamental research and new technologies whereas the observed corrugations in\nthe third dimension may shed light on subtle reasons behind the stability of 2D\ncrystals."
    },
    {
        "anchor": "An atomic Boltzmann machine capable of on-chip learning: The Boltzmann Machine (BM) is a neural network composed of stochastically\nfiring neurons that can learn complex probability distributions by adapting the\nsynaptic interactions between the neurons. BMs represent a very generic class\nof stochastic neural networks that can be used for data clustering, generative\nmodelling and deep learning. A key drawback of software-based stochastic neural\nnetworks is the required Monte Carlo sampling, which scales intractably with\nthe number of neurons. Here, we realize a physical implementation of a BM\ndirectly in the stochastic spin dynamics of a gated ensemble of coupled cobalt\natoms on the surface of semiconducting black phosphorus. Implementing the\nconcept of orbital memory utilizing scanning tunnelling microscopy, we\ndemonstrate the bottom-up construction of atomic ensembles whose stochastic\ncurrent noise is defined by a reconfigurable multi-well energy landscape.\nExploiting the anisotropic behaviour of black phosphorus, we build ensembles of\natoms with two well-separated intrinsic time scales that represent neurons and\nsynapses. By characterizing the conditional steady-state distribution of the\nneurons for given synaptic configurations, we illustrate that an ensemble can\nrepresent many distinct probability distributions. By probing the intrinsic\nsynaptic dynamics, we reveal an autonomous reorganization of the synapses in\nresponse to external electrical stimuli. This self-adaptive architecture paves\nthe way for on-chip learning directly in atomic-scale machine learning\nhardware.",
        "positive": "Ultra-low carrier density superconducting bolometers with single photon\n  sensitivity based on magic-angle twisted bilayer graphene: The superconducting (SC) state of magic-angle twisted bilayer graphene\n(MATBG) shows exceptional properties, as it consists of an unprecedentedly\nsmall electron (hole) ensemble of only ~ 10 power 11 carriers per square\ncentimeter, which is five orders of magnitude lower than in traditional\nsuperconductors. This results in an ultra-low electronic heat capacity and\nkinetic inductance of this truly two-dimensional SC, and provides\nrecord-breaking key parameters for a variety of quantum sensing applications,\nin particular in thermal sensing and single photon detection (SPD), which\ntraditionally exploit thermal effects in nanostructured superconducting thin\nfilms. In this work, we systematically study the interaction of the\nsuperconducting state of MATBG with individual light quanta. We discover full\ndestruction of the SC state upon absorption of a single infrared photon even in\na 16 square micrometer sized device, which showcases its exceptional bolometric\nsensitivity. Upon voltage biasing close to its critical current, we further\nshow that this non-optimized device can be used as a SPD, whose click-rate is\nproportional to the number of absorbed photons, following Poissonian\nstatistics. Our work offers insights into the MATBG-photon interaction and\nshows up pathways to use low-carrier density graphene-based superconductors as\na new platform for developing revolutionary new quantum devices and sensors."
    },
    {
        "anchor": "Divergence of effective mass in 'Uncorrelated State Percolation' Model: We want to answer the question of whether the divergence in the effective\nmass in metal-insulator transition (MIT) in 2DEG is in the same universality\nclass as percolation. We use a model to make Percolated state in 2D and then\ncalculate the effective mass in a super-cell and the Bloch Theorem. It is seen\nthat the effective mass, m*, scales as m*~(P-Pc)^a with a=1 and Pc being the\n(classical) percolation threshold.",
        "positive": "Electric-field induced switching from fcc to hcp stacking of a single\n  layer of Fe/Ni(111): We present a detailed study of an electric-field induced phase transition of\na single layer of Fe on a Ni(111) substrate. Scanning tunneling microscopy at 4\nK substrate temperature is used to provide the necessary electric field and to\nfollow the transition from face-centered cubic to hexagonal closepacked\nstacking with atomic resolution."
    },
    {
        "anchor": "Characterization of hexagonal boron nitride layers on nickel surfaces by\n  low-energy electron microscopy: The thickness and interfacial geometry of hexagonal boron nitride (hBN) films\ngrown by chemical vapor deposition on polycrystalline nickel foils is studied\nusing low-energy electron microscopy (LEEM). The reflectivity of the electrons,\nmeasured over an energy range of 0 - 20 eV, reveals distinct minima and maxima.\nThe measured data is compared with simulations based on a first-principles\ndescription of the electronic structure of the material. From this comparison,\nthe number of hBN layers and the separation between the lowest hBN layer and\nthe nickel surface is deduced. The coupling of interlayer states of the hBN to\nboth image-potential and Shockley-type surface states of the nickel is\ndiscussed, and the dependence of the reflectivity spectra on the surface\norientation of nickel grains is examined.",
        "positive": "Perturbative regimes in central spin models: Central spin models describe several types of solid state nanostructures\nwhich are presently considered as possible building blocks of future quantum\ninformation processing hardware. From a theoretical point of view, a key issue\nremains the treatment of the flip-flop terms in the Hamiltonian in the presence\nof a magnetic field. We systematically study the influence of these terms, both\nas a function of the field strength and the size of the spin baths. We find\ncrucial differences between initial states with central spin configurations of\nhigh and such of low polarizations. This has strong implications with respect\nto the influence of a magnetic field on the flip-flop terms in central spin\nmodels of a single and more than one central spin. Furthermore, the\ndependencies on bath size and field differ from those anticipated so far. Our\nresults might open the route for the systematic search for more efficient\nperturbative treatments of central spin problems."
    },
    {
        "anchor": "Origin and spectroscopic determination of trigonal anisotropy in a\n  heteronuclear single-molecule magnet: W-band ({\\nu} ca. 94 GHz) electron paramagnetic resonance (EPR) spectroscopy\nwas used for a single-crystal study of a star-shaped Fe3Cr single-molecule\nmagnet (SMM) with crystallographically imposed trigonal symmetry. The high\nresolution and sensitivity accessible with W-band EPR allowed us to determine\naccurately the axial zero-field splitting terms for the ground (S =6) and first\ntwo excited states (S =5 and S =4). Furthermore, spectra recorded by applying\nthe magnetic field perpendicular to the trigonal axis showed a pi/6 angular\nmodulation. This behavior is a signature of the presence of trigonal transverse\nmagnetic anisotropy terms whose values had not been spectroscopically\ndetermined in any SMM prior to this work. Such in-plane anisotropy could only\nbe justified by dropping the so-called 'giant spin approach' and by considering\na complete multispin approach. From a detailed analysis of experimental data\nwith the two models, it emerged that the observed trigonal anisotropy directly\nreflects the structural features of the cluster, i.e., the relative orientation\nof single-ion anisotropy tensors and the angular modulation of single-ion\nanisotropy components in the hard plane of the cluster. Finally, since\nhigh-order transverse anisotropy is pivotal in determining the spin dynamics in\nthe quantum tunneling regime, we have compared the angular dependence of the\ntunnel splitting predicted by the two models upon application of a transverse\nfield (Berry-phase interference).",
        "positive": "Quantum Hall Effects in Graphene-Based Two-Dimensional Electron Systems: In this article we review the quantum Hall physics of graphene based\ntwo-dimensional electron systems, with a special focus on recent experimental\nand theoretical developments. We explain why graphene and bilayer graphene can\nbe viewed respectively as J=1 and J=2 chiral two-dimensional electron gases\n(C2DEGs), and why this property frames their quantum Hall physics. The current\nstatus of experimental and theoretical work on the role of electron-electron\ninteractions is reviewed at length with an emphasis on unresolved issues in the\nfield, including assessing the role of disorder in current experimental\nresults. Special attention is given to the interesting low magnetic field limit\nand to the relationship between quantum Hall effects and the spontaneous\nanomalous Hall effects that might occur in bilayer graphene systems in the\nabsence of a magnetic field."
    },
    {
        "anchor": "Nonlinear quantum heat transfer in hybrid structures: Sufficient\n  conditions for thermal rectification: We present a unified description of heat flow in two-terminal hybrid quantum\nsystems. Using simple models, we analytically study nonlinear aspects of heat\ntransfer between various reservoirs: metals, solids, and spin baths, mediated\nby the excitation/relaxation of a central (subsystem) mode. We demonstrate rich\nnonlinear current-temperature characteristics, originating from either the\nmolecular anharmonicity, or the reservoirs (complex) energy spectra. In\nparticular, we establish sufficient conditions for thermal rectification in\ntwo-terminal junctions. We identify two classes of rectifiers. In type-A\nrectifiers the density of states of the reservoirs are dissimilar. In type-B\nrectifiers the baths are identical, but include particles whose statistics\ndiffer from that of the subsystem, to which they asymmetrically couple.\nNonlinear heat flow, and specifically thermal rectification, are thus\nubiquitous effects that could be observed in a variety of systems, phononic,\nelectronic, and photonic.",
        "positive": "Waiting time distributions of electron transfers through quantum dot\n  Aharonov-Bohm interferometers: We present a statistical readout method for quantum interferences based on\ntime series analysis of consecutive single electron transfers through a double\nquantum dot Aharonov-Bohm interferometer. Waiting time distributions\nqualitatively indicate the presence of interferences and provide information on\norbital-detuning and coherent interdot-electron transfer. Interdot transfer\ninduced oscillations are Aharonov-Bohm phase sensitive, while those due to\nlevel detuning are phase-independent. The signature of the quantum interference\nin the waiting time distribution is more apparent for weakly coupled electron\ntransfer detectors."
    },
    {
        "anchor": "The Theory of Spin Noise Spectroscopy: A Review: Direct measurements of spin fluctuations are becoming the mainstream approach\nfor studies of complex condensed matter, molecular, nuclear, and atomic\nsystems. This review covers recent progress in the field of optical Spin Noise\nSpectroscopy (SNS) with an additional goal to establish an introduction into\nits theoretical foundations. Various theoretical techniques that have been\nrecently used to interpret results of SNS measurements are explained alongside\nwith examples of their applications.",
        "positive": "Relaxation of charge in monolayer graphene: fast non-linear diffusion vs\n  Coulomb effects: Pristine monolayer graphene exhibits very poor screening because the density\nof states vanishes at the Dirac point. As a result, charge relaxation is\ncontrolled by the effects of zero-point motion (rather than by the Coulomb\ninteraction) over a wide range of parameters. Combined with the fact that\ngraphene possesses finite intrinsic conductivity, this leads to a regime of\nrelaxation described by a non-linear diffusion equation with a diffusion\ncoefficient that diverges at zero charge density. Some consequences of this\nfast diffusion are self-similar superdiffusive regimes of relaxation, the\ndevelopment of a charge depleted region at the interface between electron- and\nhole-rich regions, and finite extinction times for periodic charge profiles."
    },
    {
        "anchor": "Non-Hermitian extensions of higher-order topological phases and their\n  biorthogonal bulk-boundary correspondence: Non-Hermitian Hamiltonians, which describe a wide range of dissipative\nsystems, and higher-order topological phases, which exhibit novel boundary\nstates on corners and hinges, comprise two areas of intense current research.\nHere we investigate systems where these frontiers merge and formulate a\ngeneralized biorthogonal bulk-boundary correspondence, which dictates the\nappearance of boundary modes at parameter values that are, in general,\nradically different from those that mark phase transitions in periodic systems.\nBy analyzing the interplay between corner/hinge, edge/surface and bulk degrees\nof freedom we establish that the non-Hermitian extensions of higher-order\ntopological phases exhibit an even richer phenomenology than their Hermitian\ncounterparts and that this can be understood in a unifying way within our\nbiorthogonal framework. Saliently this works in the presence of the\nnon-Hermitian skin effect, and also naturally encompasses genuinely\nnon-Hermitian phenomena in the absence thereof.",
        "positive": "The influence of anisotropic gate potentials on the phonon induced\n  spin-flip rate in GaAs quantum dots: We study the anisotropic orbital effect in the electric field tunability of\nthe phonon induced spin-flip rate in quantum dots (QDs). Our study shows that\nanisotropic gate potential enhances the spin-flip rate and reduces the level\ncrossing point to a lower quantum dot radius due to the suppression of the\nLand$\\acute{e}$ g-factor towards bulk crystal. In the range of $10^4-10^6$\nV/cm, the electric field tunability of the phonon induced spin-flip rate can be\nmanipulated through strong Dresselhaus spin-orbit coupling. These results might\nassist the development of a spin based solid state quantum computer by\nmanipulating phonon induced spin-flip rate through spin-orbit coupling with the\napplication of anisotropic gate potential in a regime where the g-factor\nchanges its sign."
    },
    {
        "anchor": "Observation of flat bands in gated semiconductor artificial graphene: Flat bands near M points in the Brillouin zone are key features of honeycomb\nsymmetry in artificial graphene (AG) where electrons may condense into novel\ncorrelated phases. Here we report the observation of van Hove singularity\ndoublet of AG in GaAs quantum well transistors, which presents the evidence of\nflat bands in semiconductor AG. Two emerging peaks in photoluminescence spectra\ntuned by backgate voltages probe the singularity doublet of AG flat bands, and\ndemonstrate their accessibility to the Fermi level. As the Fermi level crosses\nthe doublet, the spectra display dramatic stability against electron density,\nindicating interplays between electron-electron interactions and honeycomb\nsymmetry. Our results provide a new flexible platform to explore intriguing\nflat band physics.",
        "positive": "Surface conduction and pi-bonds in graphene and topological insulator\n  Bi2Se3: A hybrid orbital model for the topological insulator Bi2Se3 is proposed and\ncompared to that of graphene. The existence of a pi-bond trimer on the Se1\nlayer at the van der Waals gap and on the surface is thought to be responsible\nfor the unusual surface conduction mechanism found in Bi2Se3 as a topological\ninsulator. The three pi-bonds are locked as permanent electric dipoles between\nthe Se1 layers in the van der Waals gap as an attractive force for the bulk as\na gapped semiconductor. In contrast, the pi-bond trimers on the surface are\nunlocked and exhibit two degenerate quantum states, creating a local charge\ntransfer mechanism in the cross-bridge model that is responsible for the\nsurface conduction. The role of pi-bonds on the Bi2Se3 surface is compared with\nthat in graphene for a similar 2D band structure containing Dirac cones."
    },
    {
        "anchor": "Electric-dipole-induced spin resonance in a lateral double quantum dot\n  incorporating two single domain nanomagnets: On-chip magnets can be used to implement relatively large local magnetic\nfield gradients in na- noelectronic circuits. Such field gradients provide\npossibilities for all-electrical control of electron spin-qubits where\nimportant coupling constants depend crucially on the detailed field\ndistribution. We present a double quantum dot (QD) hybrid device laterally\ndefined in a GaAs / AlGaAs het- erostructure which incorporates two single\ndomain nanomagnets. They have appreciably different coercive fields which\nallows us to realize four distinct configurations of the local inhomogeneous\nfield distribution. We perform dc transport spectroscopy in the Pauli-spin\nblockade regime as well as electric-dipole-induced spin resonance (EDSR)\nmeasurements to explore our hybrid nanodevice. Characterizing the two\nnanomagnets we find excellent agreement with numerical simulations. By\ncomparing the EDSR measurements with a second double QD incorporating just one\nnanomagnet we reveal an important advantage of having one magnet per QD: It\nfacilitates strong field gradients in each QD and allows to control the\nelectron spins individually for instance in an EDSR experi- ment. With just one\nsingle domain nanomagnet and common QD geometries EDSR can likely be performed\nonly in one QD.",
        "positive": "Extreme sensitivity of graphene photoconductivity to environmental gases: Graphene is a single layer of covalently bonded carbon atoms, which was\ndiscovered only 8 years ago and yet has already attracted intense research and\ncommercial interest. Initial research focused on its remarkable electronic\nproperties, such as the observation of massless Dirac fermions and the\nhalf-integer quantum Hall effect. Now graphene is finding application in\ntouch-screen displays, as channels in high-frequency transistors and in\ngraphene-based integrated circuits. The potential for using the unique\nproperties of graphene in terahertz-frequency electronics is particularly\nexciting; however, initial experiments probing the terahertz-frequency response\nof graphene are only just emerging. Here we show that the photoconductivity of\ngraphene at terahertz frequencies is dramatically altered by the adsorption of\natmospheric gases, such as nitrogen and oxygen. Furthermore, we observe the\nsignature of terahertz stimulated emission from gas-adsorbed graphene. Our\nfindings highlight the importance of environmental conditions on the design and\nfabrication of high-speed, graphene-based devices."
    },
    {
        "anchor": "Geometric focusing of supercurrent in hourglass-shaped ballistic\n  Josephson junctions: The response of superconductor-normal-metal-superconductor junctions to\nmagnetic field is complicated and non-universal because all trajectories\ncontributing to supercurrent have a different effective area, and therefore\nacquire arbitrary magnetic phases. We design an hourglass-shaped Josephson\njunction where due to the junction symmetry the magnetic phase of every\ntrajectory is approximately equal. By doing so we are able to increase a\ncritical field of the Josephson junction to many flux quanta per junction area.\nWe then analyse how breaking the symmetry condition increases the sensitivity\nof the junction, and show that our device allows to detect supercurrent carried\nby ballistic trajectories of Andreev quasiparticles.",
        "positive": "Fractional charge and inter-Landau level states at points of singular\n  curvature: The quest for universal signatures of topological phases is fundamentally\nimportant since these properties are robust to variations in system-specific\ndetails. Here we present general results for the response of quantum Hall\nstates to points of singular curvature in real space. Such topological\nsingularities may be realized, for instance, at the vertices of a cube, the\napex of a cone, etc. We find, using continuum analytical methods, that the\npoint of curvature binds an excess fractional charge. In addition, sequences of\nstates split away, energetically, from the degenerate bulk Landau levels.\nImportantly, these inter-Landau level states are bound to the topological\nsingularity and have energies that are $\\emph{universal}$ functions of bulk\nparameters and the curvature. Remarkably, our exact diagonalization of lattice\ntight-binding models on closed manifolds shows that these results continue to\nhold even when lattice effects are significant, where the applicability of\ncontinuum techniques could not have been justified a priori. Moreover, we\npropose how these states may be readily experimentally actualized. An immediate\ntechnological implication of these results is that these inter-Landau level\nstates, being as they are $\\emph{both}$ energetically and spatially isolated\nquantum states, are promising candidates for constructing qubits for quantum\ncomputation."
    },
    {
        "anchor": "Reentrant quantum anomalous Hall effect in molecular beam epitaxy-grown\n  MnBi2Te4 thin films: In this study, we investigate intrinsic magnetic topological insulator\nMnBi2Te4 thin films grown by molecular beam epitaxy. We observe a reentrant\nquantum anomalous Hall effect when the Fermi energy enters the valance band and\nmagnetic field equals zero, indicating the emergence of the Chern Anderson\ninsulator state. The discovery opens a new avenue for realizing the QAH effect\nand underscores the fundamental role of both Berry curvature and Anderson\nlocalization.",
        "positive": "Robust Formation of Ultrasmall Room-Temperature Ne\u00e9l Skyrmions in\n  Amorphous Ferrimagnets from Atomistic Simulations: Ne\\'el skyrmions originate from interfacial Dzyaloshinskii Moriya interaction\n(DMI). Recent studies have explored using thin-film ferromagnets and\nferrimagnets to host Ne\\'el skyrmions for spintronic applications. However, it\nis unclear if ultrasmall (10 nm or less) skyrmions can ever be stabilized at\nroom temperature for practical use in high density parallel racetrack memories.\nWhile thicker films can improve stability, DMI decays rapidly away from the\ninterface. As such, spins far away from the interface would experience\nnear-zero DMI, raising question on whether or not unrealistically large DMI is\nneeded to stabilize skyrmions, and whether skyrmions will also collapse away\nfrom the interface. To address these questions, we have employed atomistic\nstochastic Landau-Lifshitz-Gilbert simulations to investigate skyrmions in\namorphous ferrimagnetic GdCo. It is revealed that a significant reduction in\nDMI below that of Pt is sufficient to stabilize ultrasmall skyrmions even in\nfilms as thick as 15 nm. Moreover, skyrmions are found to retain a uniform\ncolumnar shape across the film thickness despite the decaying DMI. Our results\nshow that increasing thickness and reducing DMI in GdCo can further reduce the\nsize of skyrmions at room temperature, which is crucial to improve the density\nand energy efficiency in skyrmion based devices."
    },
    {
        "anchor": "Molecular Doping of Graphene: Graphene, a one-atom thick zero gap semiconductor [1, 2], has been attracting\nan increasing interest due to its remarkable physical properties ranging from\nan electron spectrum resembling relativistic dynamics [3-12] to ballistic\ntransport under ambient conditions [1-4]. The latter makes graphene a promising\nmaterial for future electronics and the recently demonstrated possibility of\nchemical doping without significant change in mobility has improved graphene's\nprospects further [13]. However, to find optimal dopants and, more generally,\nto progress towards graphene-based electronics requires understanding the\nphysical mechanism behind the chemical doping, which has been lacking so far.\nHere, we present the first joint experimental and theoretical investigation of\nadsorbates on graphene. We elucidate a general relation between the doping\nstrength and whether or not adsorbates have a magnetic moment: The paramagnetic\nsingle NO2 molecule is found to be a strong acceptor, whereas its diamagnetic\ndimer N2O4 causes only weak doping. This effect is related to the peculiar\ndensity of states of graphene, which provides an ideal situation for model\nstudies of doping effects in semiconductors. Furthermore, we explain recent\nresults on its \"chemical sensor\" properties, in particular, the possibility to\ndetect a single NO2 molecule [13].",
        "positive": "Transient tunneling current of single electron transistors: The transient tunneling current of single electron transistors (SETs) is\ntheoretically investigated. The time-dependent current formula given by Jauho,\nWingreen and Meir [Phys. Rev. B 50, 5528 (1994)] is applied to study the\ntemperature effect on the transient current through a single quantum dot\nembedded into asymmetry barrier. It is found that the tunneling rate ratio\nsignificantly influences the feature of transient current. Finally, the\noscillation structures on the exponential growth transient current of single\nhole transistors composed of germanium quantum dots is analyzed."
    },
    {
        "anchor": "In-flight detection of few electrons using a singlet-triplet spin qubit: We investigate experimentally the capacitive coupling between a two-electron\nsinglet-triplet spin qubit and flying electrons propagating in quantum Hall\nedge channels. After calibration of the spin qubit detector, we assess its\ncharge sensibility and demonstrate experimentally the detection of less than\nfive flying electrons with average measurement. This experiment demonstrates\nthat the spin qubit is an ultrasensitive and fast charge detector with the\nperspective of a future single shot-detection of a single flying electron. This\nwork opens the route toward quantum electron optics experiments at the single\nelectron level in semiconductor circuits.",
        "positive": "Topological chiral interface states beyond insulators: We show how to engineer a chiral spectral flow of interface states in a\ngapless system. Although the bulk bands touch -- thus making the topological\nindices of the bands ill-defined -- this spectral flow has a topological origin\nthat makes it robust even when it coexists with the bulk bands. This phenomenon\nis illustrated with an adiabatically modulated photonic quantum walk."
    },
    {
        "anchor": "The effect of noise fluctuation of a quantum tunneling device coupled to\n  a substrate: The recent experiment of Stettenheim, et al. showed that, contrary to\nconventional belief, the coupling of a quantum electronic device to its\nsubstrate can have important effects on the noise power spectrum, since the\nsubstrate functions as a mechanical oscillator. We carry out a theoretical\nanalysis of this coupling in the case of a quantum point contact (QPC). First\nwe derive the noise power spectrum from the Hamiltonian without making the\nMarkovian approximation, and obtain numerical results that reproduce the\nexperimental data. Next we investigate the nature of the coupling. In most\nprevious analyses, the coupling of an electronic device to a mechanical\noscillator has been modeled as a position coupling. We model it both as a\nposition coupling and as a momentum coupling and compare the results. We find\nthat, as long as one includes backaction between position and momentum, the\nassumed mode of coupling makes little difference, since the backaction\ntransmits momentum fluctuations to position fluctuations and vice versa.\nFinally, we ask whether the salient features of the model persist in the\nMarkovian approximation. We find that a Markovian analysis confirms the\nQPC-substrate coupling, but underestimates the noise floor and leads to\nexcessively sharp and narrow noise peaks around the resonant frequencies.",
        "positive": "Shot-noise measurements of single-atom junctions: Current fluctuations related to the discreteness of charge passing through\nsmall constrictions are termed shot noise. This unavoidable noise provides both\nadvantages - being a direct measurement of the transmitted particles' charge,\nand disadvantages - a main noise source in nanoscale devices operating at low\ntemperature. While better understanding of shot noise is desired, the technical\ndifficulties in measuring it result in relatively few experimental works,\nespecially in single-atom structures. Here we describe a local shot-noise\nmeasurement apparatus, and demonstrate successful noise measurements through\nsingle-atom junctions. Our apparatus, based on a scanning tunneling microscope\noperates at liquid helium temperatures. It includes a broadband commercial\namplifier mounted in close proximity to the tunnel junction, thus reducing both\nthermal noise and the input capacitance that limit traditional noise\nmeasurements. The full capabilities of the microscope are maintained in the\nmodified system and a quick transition between different measurement modes is\npossible."
    },
    {
        "anchor": "Evolutionary optimization of all-dielectric magnetic nanoantennas: Magnetic light and matter interactions are generally too weak to be detected,\nstudied and applied technologically. However, if one can increase the magnetic\npower density of light by several orders of magnitude, the coupling between\nmagnetic light and matter could become of the same order of magnitude as the\ncoupling with its electric counterpart. For that purpose, photonic nanoantennas\nhave been proposed, and in particular dielectric nanostructures, to engineer\nstrong local magnetic field and therefore increase the probability of magnetic\ninteractions. Unfortunately, dielectric designs suffer from physical\nlimitations that confine the magnetic hot spot in the core of the material\nitself, preventing experimental and technological implementations. Here, we\ndemonstrate that evolutionary algorithms can overcome such limitations by\ndesigning new dielectric photonic nanoantennas, able to increase and extract\nthe optical magnetic field from high refractive index materials. We also\ndemonstrate that the magnetic power density in an evolutionary optimized\ndielectric nanostructure can be increased by a factor 5 compared to state of\nthe art dielectric nanoantennas. In addition, we show that the fine details of\nthe nanostructure are not critical in reaching these aforementioned features,\nas long as the general shape of the motif is maintained. This advocates for the\nfeasibility of nanofabricating the optimized antennas experimentally and their\nsubsequent application. By designing all dielectric magnetic antennas that\nfeature local magnetic hot-spots outside of high refractive index materials,\nthis work highlights the potential of evolutionary methods to fill the gap\nbetween electric and magnetic light-matter interactions, opening up new\npossibilities in many research fields.",
        "positive": "Spin motive force by the momentum-space Berry phase in magnetic Weyl\n  semimetals: We show that the magnetic precession of ferromagnetic moments in a\nnoncentrosymmetric magnetic Weyl semimetal induces an electric current through\na mechanism analogous to the adiabatic charge pumping. The current is a\nconsequence of a Berry phase in the momentum space resulting from the circular\nmotion of Weyl nodes induced by the precession. This mechanism resembles the\nFaraday effect, namely, induced magnetic field by circular electric current.\nThe circular motion of Weyl nodes induces magnetic charge current in the\nmomentum space, which results in a Berry phase that describes the adiabatic\npump. Experimentally, this phenomenon is similar to spin motive force, which is\nan electric current induced by magnetic precision in the presence of the\nspatial gradient of magnetization. However, unlike the conventional spin motive\nforce, this current occurs without a magnetization gradient. The result\ndemonstrates a nontrivial interplay between the topological electronic state\nand magnetic dynamics."
    },
    {
        "anchor": "Non-equilibrium Mott transition in a lattice of Bose-Einstein\n  condensates: We study the non-equilibrium dynamics of the zero temperature Mott insulator-\nsuperfluid quantum phase transition in a lattice of weakly coupled\nBose-Einstein condensates. We show that crossing the critical point from the\ninsulating to the superfluid phase at a finite rate results in a finite\ndispersion of current. Viceversa, crossing the critical point from the\nsuperfluid phase to the insulating one, results in a finite dispersion of the\nnumber of atoms per lattice site. We develop a microscopic dynamical model of\nthe transition, and make quantitative predictions for realistic experiments.",
        "positive": "Recent progresses of quantum confinement in graphene quantum dots: Graphene quantum dots (GQDs) not only have potential applications on spin\nqubit,but also serve as essential platforms to study the fundamental properties\nof Dirac fermions, such as Klein tunneling and Berry phase. By now, the study\nof quantum confinement in GQDs still attract much attention in condensed matter\nphysics. In this article, we review the experimental progresses on quantum\nconfinement in GQDs mainly by using scanning tunneling microscopy (STM) and\nscanning tunneling spectroscopy (STS). Here, the GQDs are divided into Klein\nGQDs, bound-state GQDs and edge-terminated GQDs according to their different\nconfinement strength. Based on the realization of quasi-bound states in Klein\nGQDs, external perpendicular magnetic field is utilized as a manipulation\napproach to trigger and control the novel properties by tuning Berry phase and\nelectron-electron (e-e) interaction. The tip induced edge-free GQDs can serve\nas an intuitive mean to explore the broken symmetry states at nanoscale and\nsingle-electron accuracy, which are expected to be used in studying physical\nproperties of different two-dimentional materials. Moreover, high-spin magnetic\nground states are successfully introduced in edge-terminated GQDs by designing\nand synthesizing triangulene zigzag nanographenes."
    },
    {
        "anchor": "Graphene-based Bolometers: This article reviews recent research for development of sensitive graphene\nphoton detectors in the infrared/far infrared/THz range. For this range,\ngraphene has promising potential in thermal photon detectors. Graphene has\nultra-small volume and low electron density, which gives relatively large\nheating per absorbed photon and fast response. At low temperatures the\nelectron-phonon energy loss is small, so ultrasensitive power detection is\npossible. We review recent research on the science base of such detectors, and\noutline the major design challenges. Important factors that must be considered\nin making useful detectors include the photon and readout coupling efficiency,\nthe method of electron temperature readout, and thermal isolation of the hot\nelectrons.",
        "positive": "Projective Construction of Non-Abelian Quantum Hall Liquids: Using projective construction, a generalized parton construction, we\nconstruct many non-Abelian quantum Hall (QH) states, which include the Pfaffian\nstate at filling fraction $\\nu=1/2$. The projective construction allows us to\ncalculate the bulk and the edge effective theory for the constructed QH state.\nWe illustrate how to use the bulk effective theory to calculate the ground\nstate degeneracy of non-Abelian QH liquids on torus. We point out that the full\ndescription of the effective theory requires both the effective Lagrangian and\nthe definition of electron operators. The latter generates all physical states\nand defines the gauge structure of the theory."
    },
    {
        "anchor": "Anisotropic and tunable optical conductivity of a two-dimensional\n  semi-Dirac system in the presence of elliptically polarized radiation: We investigate the effect of ellipticity ratio of the polarized radiation\nfield on optoelectronic properties of a two-dimensional (2D) semi-Dirac (SD)\nsystem. The optical conductivity is calculated within the energy balance\nequation approach derived from the semiclassical Boltzmann equation. We find\nthat there exists the anisotropic optical absorption induced via both the\nintra- and interband electronic transition channels in the perpendicular $xx$\nand $yy$ directions. Furthermore, we examine the effects of the ellipticity\nratio, the temperature, the carrier density, and the band-gap parameter on the\noptical conductivity of the 2D SD system placed in transverse and vertical\ndirections, respectively. It is shown that the ellipticity ratio, temperature,\ncarrier density, and band-gap parameter can play the important roles in tuning\nthe strength, peak position, and shape of the optical conductivity spectrum.\nThe results obtained from this study indicate that the 2D SD system can be a\npromising anisotropic and tunable optical and optoelectronic material for\napplications in innovative 2D optical and optoelectronic devices, which are\nactive in the infrared and terahertz bandwidths.",
        "positive": "Quantum many-body theory for electron spin decoherence in nanoscale\n  nuclear spin baths: Decoherence of electron spins in nanoscale systems is important to quantum\ntechnologies such as quantum information processing and magnetometry. It is\nalso an ideal model problem for studying the crossover between quantum and\nclassical phenomena. At low temperatures or in light-element materials where\nthe spin-orbit coupling is weak, the phonon scattering in nanostructures is\nless important and the fluctuations of nuclear spins become the dominant\ndecoherence mechanism for electron spins. Since 1950s, semiclassical noise\ntheories have been developed for understanding electron spin decoherence. In\nspin-based solid-state quantum technologies, the relevant systems are in the\nnanometer scale and the nuclear spin baths are quantum objects which require a\nquantum description. Recently, quantum pictures have been established to\nunderstand the decoherence and quantum many-body theories have been developed\nto quantitatively describe this phenomenon. Anomalous quantum effects have been\npredicted and some have been experimentally confirmed. A systematically\ntruncated cluster correlation expansion theory has been developed to account\nfor the many-body correlations in nanoscale nuclear spin baths that are built\nup during the electron spin decoherence. The theory has successfully predicted\nand explained a number of experimental results in a wide range of physical\nsystems. In this review, we will cover these recent progresses. The limitations\nof the present quantum many-body theories and possible directions for future\ndevelopment will also be discussed."
    },
    {
        "anchor": "Kondo effect in Lieb's ferrimagnetic system on the T-shaped bipartite\n  lattice: The minimal ferrimagnetism by Lieb's theorem emerges on the T-shaped\nbipartite lattice composed of four sites, which can be realized experimentally,\njust as Nagaoka ferromagnetism has been demonstrated experimentally using a\nquartet quantum-dot(J.P.Dehollain et al., Nature 579, 528 (2020).). In this\npaper, the Kondo effect on this ferrimagnetism is theoretically studied. The\nmagnetic moment $S=1$ is screened in two steps by the Kondo effect and the\nseries conductance $g_{s}$ is strongly suppressed to $g_{s}\\simeq 0$, while the\nparallel conductance $g_{p}$ has the maximum value $g_{p}\\simeq 4e^{2}/h$. The\nrobustness of these properties against a parameter change toward reducing the\nLieb's ferrimagnetism is also discussed, showing the scenarios for entanglement\nof the degrees of freedom toward the ground state.",
        "positive": "A Gate-Defined Quantum Point Contact in an InAs Two-Dimensional Electron\n  Gas: We experimentally study quantized conductance in an electrostatically defined\nconstriction in a high-mobility InAs two-dimensional electron gas. A parallel\nmagnetic field lifts the spin degeneracy and allows for the observation of\nplateaus in integer multiples of $e^2/h$. Upon the application of a\nperpendicular magnetic field, spin-resolved magnetoelectric subbands are\nvisible. Through finite bias spectroscopy we measure the subband spacings in\nboth parallel and perpendicular direction of the magnetic field and determine\nthe $g$-factor."
    },
    {
        "anchor": "Anomalous sound attenuation in Weyl semimetals in magnetic and\n  pseudomagnetic fields: We evaluate the sound attenuation in a Weyl semimetal subject to a magnetic\nfield or a pseudomagnetic field associated with a strain. Due to the interplay\nof intra- and inter-node scattering processes as well as screening, the fields\ngenerically reduce the sound absorption. A nontrivial dependence on the\nrelative direction of the magnetic field and the sound wave vector, i.e., the\nmagnetic sound dichroism, can occur in materials with nonsymmetric Weyl nodes\n(e.g., different Fermi velocities and/or relaxation times). It is found that\nthe sound dichroism in Weyl materials can also be activated by an external\nstrain-induced pseudomagnetic field. In view of the dependence on the field\ndirection, the dichroism may lead to a weak enhancement of the sound\nattenuation compared with its value at vanishing fields.",
        "positive": "Non-Abelian Evolution of a Majorana Train in a Single Josephson Junction: Demonstration of non-Abelian anyon statistics often requires dynamical\ncontrols of a complicated device that are challenging in realistic situations.\nWe propose a {\\it single} Josephson junction to detect a non-Abelian statistics\neffect of Majorana fermions, formed by two finite-size $s$-wave superconductors\non a topological insulator under a magnetic field. At certain field strengths,\na train of three localized Majorana fermions appears along the junction, while\nan extended chiral Majorana fermion encircles the train and the\nsuperconductors. A DC voltage bias across the junction causes the train to move\nand collide with the extended Majorana fermion. This involves interchange of\nfusion partners among the four Majorana fermions, leading to non-Abelian state\nevolution. The evolution gives rise to a $2n\\pi$ fractional AC Josephson effect\nwith an arbitrary integer $n\\ge2$ tunable by the voltage."
    },
    {
        "anchor": "Memristive Ising Circuits: The Ising model is of prime importance in the field of statistical mechanics.\nHere we show that Ising-type interactions can be realized in\nperiodically-driven circuits of stochastic binary resistors with memory. A key\nfeature of our realization is the simultaneous co-existence of ferromagnetic\nand antiferromagnetic interactions between two neighboring spins -- an\nextraordinary property not available in nature. We demonstrate that the\nstatistics of circuit states may perfectly match the ones found in the Ising\nmodel with ferromagnetic or antiferromagnetic interactions, and, importantly,\nthe corresponding Ising model parameters can be extracted from the\nprobabilities of circuit states. Using this finding, the Ising Hamiltonian is\nre-constructed in several model cases, and it is shown that different types of\ninteraction can be realized in circuits of stochastic memristors.",
        "positive": "Current fluctuations in a spin filter with paramagnetic impurities: We analyze the frequency dependence of shot noise in a spin filter consisting\nof a normal grain and ferromagnetic electrodes separated by tunnel barriers.\nThe source of frequency-dependent noise is random spin-flip electron scattering\nthat results from spin-orbit interaction and magnetic impurities. Though the\nlatter mechanism does not contribute to the average current, it contributes to\nthe noise and leads to its dispersion at frequencies of the order of the\nKorringa relaxation rate. Under nonequilibrium conditions, this rate is\nproportional to the applied bias $V$, but parametrically smaller than\n$eV/\\hbar$."
    },
    {
        "anchor": "Electronic and optical conductivity of kekul\u00e9-patterned graphene:\n  Intravalley and intervalley transport: A Kubo formalism is used to calculate the electronic and optical conductivity\nof a graphene superlattice with Y-shaped kekul\\'e bond texture, similar to that\nvisualized in recent experiments. We show that new conduction channels between\nthe valleys in graphene are opened by the kekul\\'e distortion. This intervalley\ncontribution to the electronic transport is not present in pristine graphene\nand here appears due to the folding of the Dirac cones $K$, $K'$ on top of each\nother. The contribution of intervalley transport to the conductivity of\ngraphene, as well as the modification of the intravalley transport, are\nanalyzed in detail for different frequency, temperature, chemical potential and\nscattering rate limits. We obtain analytical expressions for the conductivity\nthat reproduce previous expressions used to fit experimental measurements in\ngraphene and compare with direct numerical evaluations of the Kubo formula,\nfinding great agreement. The optical absorption arising from intervalley\ntransitions displays a maximum at a special frequency that can be tuned by\ndoping. Our results show how the single parameter describing the valley\ncoupling in this system could be obtained by measuring graphene's optical\nabsorbance in the region where interband transitions are blocked by the\nimpurities. Finally, we use Fermi's golden rule to independently verify some of\nthe previous results.",
        "positive": "Electrostatics and domains in ferroelectric superlattices: The electrostatics arising in ferroelectric/dielectric two-dimensional\nheterostructures and superlatitices is revisited here within a simplest Kittel\nmodel, in order to define a clear paradigmatic reference for domain formation.\nThe screening of the depolarizing field in isolated ferroelectric or polar thin\nfilms via the formation of 180$^{\\circ}$ domains is well understood, whereby\nthe width of the domains $w$ grows as the square-root of the film thickness\n$d$, following Kittel's law, for thick enough films ($w\\ll d$). This behavior\nis qualitatively unaltered when the film is deposited on a dielectric\nsubstrate, sandwiched between dielectrics, and even in a superlattice setting,\nwith just a suitable renormalisation of Kittel's length. As $d$ decreases,\n$w(d)$ deviates from Kittel's law, reaching a minimum and then diverging onto\nthe mono-domain limit for thin enough films, always assuming a given\nspontaneous polarization $P$ of the ferrolectric, only modified by linear\nresponse to the depolarizing field. In most cases of experimental relevance $P$\nwould vanish before reaching that thin-film regime. This is not the case for\nsuperlattices. Unlike single films, for which the increase of the dielectric\nconstant of the surrounding medium pushes the deviation from the Kittel's\nregime to lower values of $d$, there is a critical value of the relative\nthickness of ferroelectric/dielectric films in superlattices beyond which that\nbehavior is reversed, and which defines the separation between strong and weak\nferroelectric coupling in superlattices."
    },
    {
        "anchor": "Gapped Phases of Quantum Wires: We investigate possible nontrivial phases of a two-subband quantum wire. It\nis found that inter- and intra-subband interactions may drive the electron\nsystem of the wire into a gapped state. If the nominal electron densities in\nthe two subbands are sufficiently close to each other, then the leading\ninstability is the inter-subband charge-density wave (CDW). For large density\nimbalance, the interaction in the inter-subband Cooper channel may lead to a\nsuperconducting instability. The total charge-density mode, responsible for the\nconductance of an ideal wire, always remains gapless, which enforces the\ntwo-terminal conductance to be at the universal value of 2e^2/h per occupied\nsubband. On the contrary, the tunneling density of states (DOS) in the bulk of\nthe wire acquires a hard gap, above which the DOS has a non-universal\nsingularity. This singularity is weaker than the square-root divergency\ncharacteristic for non-interacting quasiparticles near a gap edge due to the\n\"dressing\" of massive modes by a gapless total charge density mode. The DOS for\ntunneling into the end of a wire in a CDW-gapped state preserves the power-law\nbehavior due to the frustration the edge introduces into the CDW order. This\nwork is related to the vast literature on coupled 1D systems, and most of all,\non two-leg Hubbard ladders. Whenever possible, we give derivations of the\nimportant results by other authors, adopted for the context of our study.",
        "positive": "Random Walks and Anderson Localisation in a Three-Dimensional Class C\n  Network Model: We study the disorder-induced localisation transition in a three-dimensional\nnetwork model that belongs to symmetry class C. The model represents\nquasiparticle dynamics in a gapless spin-singlet superconductor without\ntime-reversal invariance. It is a special feature of network models with this\nsymmetry that the conductance and density of states can be expressed as\naverages in a classical system of dense, interacting random walks. Using this\nmapping, we present a more precise numerical study of critical behaviour at an\nAnderson transition than has been possible previously in any context."
    },
    {
        "anchor": "On the Energy Transfer Performance of Mechanical Nanoresonators Coupled\n  with Electromagnetic Fields: We study the energy transfer performance in electrically and magnetically\ncoupled mechanical nanoresonators. Using the resonant scattering theory, we\nshow that magnetically coupled resonators can achieve the same energy transfer\nperformance as for their electrically coupled counterparts, or even outperform\nthem within the scale of interest. Magnetic and electric coupling are compared\nin the Nanotube Radio, a realistic example of a nano-scale mechanical\nresonator. The energy transfer performance is also discussed for a newly\nproposed bio-nanoresonator composed of a magnetosomes coated with a net of\nprotein fibers.",
        "positive": "Design and characterization of electronic fractals: The dimensionality of an electronic quantum system is decisive for its\nproperties. In 1D electrons form a Luttinger liquid and in 2D they exhibit the\nquantum Hall effect. However, very little is known about the behavior of\nelectrons in non-integer, i.e. fractional dimensions. Here, we show how arrays\nof artificial atoms can be defined by controlled positioning of CO molecules on\na Cu(111) surface, and how these sites couple to form electronic Sierpinski\nfractals. We characterize the electron wavefunctions at different energies with\nscanning tunneling microscopy and spectroscopy and show that they inherit the\nfractional dimension. Wavefunctions delocalized over the Sierpinski structure\ndecompose into self-similar parts at higher energy, and this scale invariance\ncan also be retrieved in reciprocal space. Our results show that electronic\nquantum fractals can be man-made by atomic manipulation in a scanning tunneling\nmicroscope. The same methodology will allow to address fundamental questions on\nthe effects of spin-orbit interaction and a magnetic field on electrons in\nnon-integer dimensions. Moreover, the rational concept of artificial atoms can\nreadily be transferred to planar semiconductor electronics, allowing for the\nexploration of electrons in a well-defined fractal geometry, including\ninteractions and external fields."
    },
    {
        "anchor": "A double quantum dot memristor: Memristive systems are generalisations of memristors, which are resistors\nwith memory. In this paper, we present a quantum description of memristive\nsystems. Using this model we propose and experimentally demonstrate a simple\nand practical scheme for realising memristive systems with quantum dots. The\napproach harnesses a phenomenon that is commonly seen as a bane of\nnanoelectronics, i.e. switching of a trapped charge in the vicinity of the\ndevice. We show that quantum-dot memristive systems have hysteresis\ncurrent-voltage characteristics and quantum jump induced stochastic behaviour.\nRealising such a quantum memristor completes the menu of components for quantum\ncircuit design.",
        "positive": "Nontrivial magnetic field related phenomena in the single-layer graphene\n  on ferroelectric substrate: The review is focused on our recent predictions of nontrivial physical\nphenomena taking place in the nanostructure single-layer grapheme on\nferroelectric substrate, which are related with magnetic field. In particular\nwe predicted that 180-degree domain walls in a strained ferroelectric film can\ninduce p-n junctions in a graphene channel and lead to the unusual temperature\nand gate voltage dependences of the perpendicular modes {\\nu} of the integer\nquantum Hall effect. The non-integer numbers and their irregular sequence\nprincipally differ from the conventional sequence {\\nu}= 3/2, 5/3. The unusual\nv-numbers originate from significantly different numbers of the edge modes,\n{\\nu}1 and {\\nu}2, corresponding to different concentration of carriers in the\nleft (n1) and right (n2) ferroelectric domains of p-n junction boundary. The\ndifference between n1 and n2 disappears with the vanishing of the film\nspontaneous polarization in a paraelectric phase, which can be varied in a wide\ntemperature range by an appropriate choice of misfit strain originated from the\nfilm-substrate lattice mismatch. Next we studied the electric conductivity of\nthe system ferromagnetic dielectric - graphene channel - ferroelectric\nsubstrate. The magnetic dielectric locally transforms the band spectrum of\ngraphene by inducing an energy gap in it and making it spin-asymmetric with\nrespect to the free electrons. It was demonstrated, that if the Fermi level in\nthe graphene channel belongs to energy intervals, where the graphene band\nspectrum, modified by EuO, becomes sharply spin-asymmetric, such a device can\nbe an ideal non-volatile spin filter. The practical application of the system\nunder consideration would be restricted by a Curie temperature of a\nferromagnet. Controlling of the Fermi level (e.g. by temperature that changes\nferroelectric polarization) can convert a spin filter to a spin valve."
    },
    {
        "anchor": "Hybrid superlattices of graphene and hexagonal boron nitride: A\n  ferromagnetic semiconductor at room temperature: Carbon (C) doped hexagonal boron nitride (hBN) has been experimentally\nreported to be ferromagnetic at room temperature. Substitution by C in hBN has\nbeen also reported to form islands of graphene. In this work we derive a\nmechanistic understanding of ferromagnetism with graphene islands in hBN from\nfirst principles and mean-field Hubbard model. We find a general property, that\nin bipartite lattices where the sublattices differ in on-site energies, as in\nhBN, the ordering between local magnetic moments can be substantial and\npredominantly anti-ferromagnetic (AFM) if they are embedded in the same\nsublattice, unless dominated by Mott like inter-sublattice spin separation due\nto strong localization. The dominant AFM order is rooted at spin resolved\nspatial separation of lone pairs of nitrogen (N) and back transferred electrons\non boron (B) due to Coulomb repulsion thus essentially implying a\nsuper-exchange pathway. Subsequently we propose a class of ferri-magnetically\nordered inter-penetrating super-lattices of magnetic graphene islands in hBN,\nwhich can be chosen to be a ferromagnetic semiconductor or a half-metal, and\nretain a net non-zero magnetic moment at room temperature.",
        "positive": "Aharonov-Casher Effect for Plasmons in a Ring of Josephson Junctions: Phase slips in a one-dimensional closed array of Josephson junctions\nhybridize the persistent current states (PCS) and plasmon branches of\nexcitations. The interference between phase slips passing through different\njunctions of the array makes the hybridization sensitive to the charges of the\nsuperconducting islands comprising the array. This in turn results in the\nAharonov-Casher effect for plasmons, which in absence of phase slips are\ninsensitive to island charges."
    },
    {
        "anchor": "Formation and properties of metal-oxygen atomic chains: Suspended chains consisting of single noble metal and oxygen atoms have been\nformed. We provide evidence that oxygen can react with and be incorporated into\nmetallic one-dimensional atomic chains. Oxygen incorporation reinforces the\nlinear bonds in the chain, which facilitates the creation of longer atomic\nchains. The mechanical and electrical properties of these diatomic chains have\nbeen investigated by determining local vibration modes of the chain and by\nmeasuring the dependence of the average chain-conductance on the length of the\nchain. Additionally, we have performed calculations that give insight in the\nphysical mechanism of the oxygen-induced strengthening of the linear bonds and\nthe conductance of the metal-oxygen chains.",
        "positive": "Nuclear magnetic resonance inverse spectra of InGaAs quantum dots:\n  Atomistic level structural information: A wealth of atomistic information is contained within a self-assembled\nquantum dot (QD), associated with its chemical composition and the growth\nhistory. In the presence of quadrupolar nuclei, as in InGaAs QDs, much of this\nis inherited to nuclear spins via the coupling between the strain within the\npolar lattice and the electric quadrupole moments of the nuclei. Here, we\npresent a computational study of the recently introduced inverse spectra\nnuclear magnetic resonance technique to assess its suitability for extracting\nsuch structural information. We observe marked spectral differences between the\ncompound InAs and alloy InGaAs QDs. These are linked to the local biaxial and\nshear strains, and the local bonding configurations. The cation-alloying plays\na crucial role especially for the arsenic nuclei. The isotopic line profiles\nalso largely differ among nuclear species: While the central transition of the\ngallium isotopes have a narrow linewidth, those of arsenic and indium are much\nbroader and oppositely skewed with respect to each other. The statistical\ndistributions of electric field gradient (EFG) parameters of the nuclei within\nthe QD are analyzed. The consequences of various EFG axial orientation\ncharacteristics are discussed. Finally, the possibility of suppressing the\nfirst-order quadrupolar shifts is demonstrated by simply tilting the sample\nwith respect to the static magnetic field."
    },
    {
        "anchor": "Spin density wave instabilities in the NbS2 monolayer: In the present work, we study the magnetic properties of the NbS2 monolayer\nby first-principles calculations. The transition metal dichalcogenides (TMDC)\nare a family of laminar materials presenting exciting properties such as charge\ndensity waves (CDW), superconductivity and metal-insulating transitions among\nothers. 2H-NbS2 is a particular case within the family, because it is the only\none that is superconductor without exhibiting a CDW order. Although no long\nrange magnetic order was experimentally observed in the TMDC, we show here that\nthe single monolayer of NbS2 is on the verge of a spin density wave (SDW)\nphase. Our calculations indicate that a wave-like magnetic order is stabilized\nin the NbS2 monolayer in the presence of magnetic defects or within zig-zag\nnanoribbons, due to the presence of unpaired electrons. We calculate the real\npart of the bare electronic susceptibilty and the corresponding nesting\nfunction of the clean NbS2 monolayer, showing that there are strong electronic\ninstabilities at the same wavevector asociated with the calculated SDWs, also\ncorresponding with one of the main nesting vectors of the Fermi surface. We\nconclude that the physical mechanism behind the spin-wave instabilities are the\nnesting properties, accentuated by the quasi 2D character of this system, and\nthe rather strong Coulomb interactions of the 4d band of the Nb atom. We also\nestimate the amplitude of the spin-fluctuations and find that they are rather\nlarge, as expected for a system on the verge of a quantum critical transition.",
        "positive": "Bistritzer-MacDonald dynamics in twisted bilayer graphene: The Bistritzer-MacDonald (BM) model, introduced in \\cite{Bistritzer2011},\nattempts to capture the electronic properties of twisted bilayer graphene\n(TBG), even at incommensurate twist angles, by an effective periodic model over\nthe bilayer moir\\'e pattern. Starting from a tight-binding model, we identify a\nregime where the BM model emerges as the effective dynamics for electrons\nmodeled as wave-packets spectrally concentrated at the monolayer Dirac points,\nup to error that can be rigorously estimated. Using measured values of relevant\nphysical constants, we argue that this regime is realized in TBG at the first\n\"magic\" angle."
    },
    {
        "anchor": "Resonant inverse Faraday effect in nanorings: A circularly polarized light can induce a dissipationless dc current in a\nquantum nanoring which is responsible for a resonant helicity-driven\ncontribution to magnetic moment. This current is not suppressed by thermal\naveraging despite its quantum nature. We refer to this phenomenon as the\nquantum resonant inverse Faraday effect. For weak electromagnetic field, when\nthe characteristic coupling energy is small compared to the energy level\nspacing, we predict narrow resonances in the circulating current and,\nconsequently, in the magnetic moment of the ring. For strong fields, the\nresonances merge into a wide peak with a width determined by the spectral\ncurvature. We further demonstrate that weak short-range disorder splits the\nresonances and induces additional particularly sharp and high resonant peaks in\ndc current and magnetization. In contrast, long-range disorder leads to a\nchaotic behavior of the system in the vicinity of the separatrix that divides\nthe phase space of the system into regions with dynamically localized and\ndelocalized states.",
        "positive": "Universality in metallic nanocohesion: a quantum chaos approach: Convergent semiclassical trace formulae for the density of states and\ncohesive force of a narrow constriction in an electron gas, whose classical\nmotion is either chaotic or integrable, are derived. It is shown that mode\nquantization in a metallic point contact or nanowire leads to universal\noscillations in its cohesive force: the amplitude of the oscillations depends\nonly on a dimensionless quantum parameter describing the crossover from chaotic\nto integrable motion, and is of order 1 nano-Newton, in agreement with recent\nexperiments. Interestingly, quantum tunneling is shown to be described\nquantitatively in terms of the instability of the classical periodic orbits."
    },
    {
        "anchor": "Polarization Dependence of Optical Transitions in Graphene Nanoribbons: The universality of $k$-dependent electron-photon and electron-phonon matrix\nelements is discussed for graphene nanoribbons and carbon nanotubes. An\nelectron undergoes a change in wavevector in the direction of broken\ntranslational symmetry, depending on the light polarization direction. We\nsuggest that this phenomenon originates from a microscopic feature of\nchirality.",
        "positive": "The pre-exponential voltage-exponent as a sensitive test parameter for\n  field emission theories: For field electron emission (FE), an empirical equation for measured current\nI_m as a function of measured voltage V_m has the form I_m =\nC*(V_m)^k*exp[-B/(V_m)], where B is a constant and C and k are constants or\nvary weakly with V_m. Values for k can be extracted (a) from simulations based\non some specific FE theory, and in principle (b) from current-voltage\nmeasurements of sufficiently high quality. This paper shows that comparison of\ntheoretically derived and experimentally derived k-values could provide a\nsensitive and useful tool for comparing FE theory and experiment, and for\nchoosing between alternative theories. Existing methods of extracting k-values\nfrom experimental or simulated current-voltage data are discussed, including a\nmodernised \"least residual\" method, and existing knowledge concerning k-values\nis summarised. Exploratory simulations are reported. Where an analytical result\nfor k is independently known, this value is reliably extracted. More generally,\nextracted k-values are sensitive to details of the emission theory used, but\nalso depend on assumed emitter shape; these two influences will need to be\ndisentangled by future research, and a range of emitter shapes will need\nexamination. Other procedural conclusions are reported. Some scientific issues\nthat this new tool may be able to help investigate are indicated."
    },
    {
        "anchor": "Calculation of dephasing times in closed quantum dots: Dephasing of one-particle states in closed quantum dots is analyzed within\nthe framework of random matrix theory and Master equation. Combination of this\nanalysis with recent experiments on the magnetoconductance allows for the first\ntime to evaluate the dephasing times of closed quantum dots. These dephasing\ntimes turn out to depend on the mean level spacing and to be significantly\nenhanced as compared with the case of open dots. Moreover, the experimental\ndata available are consistent with the prediction that the dephasing of\none-particle states in finite closed systems disappears at low enough energies\nand temperatures.",
        "positive": "Method for Full Bloch-Sphere Control of a Localized Spin via a Single\n  Electrical Gate: We calculate the dependence on an applied electric field of the g tensor of a\nsingle electron in a self-assembled InAs/GaAs quantum dot. We identify dot\nsizes and shapes for which one in-plane component of the g tensor changes sign\nfor realistic electric fields, and show this should permit full Bloch-sphere\ncontrol of the electron spin in the quantum dot using only a static magnetic\nfield and a single vertical electric gate."
    },
    {
        "anchor": "Investigation of Magnetic Domain Structure in Bi0.7Dy0.3FeO3 thin films\n  integrated with ZnO film: The magnetic domain structure of the multiferroic Bi1-xDyxFeO3 (BDFO)\ndeposited on ZnO at the macroscopic level has been demonstrated in this paper.\nMagnetic properties are observed by saturated magnetic and ferroelectric\nhysteresis loops at room temperature. The coupling behaviour and magnetic\ntransition are verified using Multimode Atomic Force Microscope by applying\nbias between sample and MFM tip. ZnO thin film of 300 nm was deposited by\ndielectric sputtering using a ZnO target on Si p-type conducting (.0001-0005\n{\\Omega} cm) substrate. BDFO thin films of 300 nm were deposited on Si/ZnO\nusing PLD (Pulsed laser deposition) technique. It is observed that BDFO thin\nfilms integrated with ZnO film shows the coexistence of ferromagnetic and\nferroelectric ordering with significant coupling at room temperature.\nIntegration of BDFO films with ZnO piezoelectric thin film shows the potential\nin MEMS applications as well as in Memory devices and strong history dependent\nsystems.",
        "positive": "Second- and third-order optical susceptibilities in bidimensional\n  semiconductors near excitons states: Semiconducting Transition Metal Dichalcogenides (TMDs) have significant\nnonlinear optical effects. In this work we have used second-harmonic generation\n(SHG) and the four-wave mixing (FWM) spectroscopy in resonance with the\nexcitons in MoS2, MoSe2, and WS2 monolayers to characterize the nonlinear\noptical properties of these materials. We show that trions and excitons are\nresponsible for enhancing the nonlinear optical response, and determine the\nexciton and trion energies by comparing with the photoluminescence spectra.\nMoreover, we extract the second and third order optical sheet susceptibility\nnear exciton energies and compare with values found in the literature. We also\ndemonstrate the ability to generate different nonlinear effects in a wide\nspectral range in the visible region for monolayer MoS2, opening the\npossibility of using two-dimensional materials for nonlinear optoelectronic and\nphotonic applications."
    },
    {
        "anchor": "Fractional boundary charges in quantum dot arrays with density\n  modulation: We show that fractional charges can be realized at the boundaries of a linear\narray of tunnel coupled quantum dots in the presence of a periodically\nmodulated onsite potential. While the charge fractionalization mechanism is\nsimilar to the one in polyacetylene, here the values of fractional charges can\nbe tuned to arbitrary values by varying the phase of the onsite potential or\nthe total number of dots in the array. We also find that the fractional\nboundary charges, unlike the in-gap bound states, are stable against static\nrandom disorder. We discuss the minimum array size where fractional boundary\ncharges can be observed.",
        "positive": "Signatures of discrete time-crystallinity in transport through an open\n  Fermionic chain: Discrete time-crystals are periodically driven quantum many-body systems with\nbroken discrete-time translational symmetry, a non-equilibrium steady state\nrepresenting self-organization of motion of quantum particles. Observations of\ndiscrete time-crystalline order are currently limited to magneto-optical\nexperiments. Crucially, it was never observed in a transport experiment\nperformed on systems connected to external electrodes. Here we demonstrate that\nboth discrete time-crystal and quasi-crystal survive a very general class of\nenvironment corresponding to single-particle gain and loss through\nsystem-electrode coupling over experimentally relevant timescales. Using\ndynamical symmetries, we analytically identify the conditions for observing\ntime-crystalline behavior in a periodically driven open Fermi-Hubbard chain\nattached to electrodes. Remarkably, the spin-polarized transport current\ndirectly manifests the existence of a time-crystalline behavior. Our findings\nare verifiable in present-day experiments with quantum-dot arrays and Fermionic\nultra-cold atoms in optical lattices."
    },
    {
        "anchor": "Tight Binding Parametrization of Few-layer Black Phosphorus from\n  First-Principles Calculations: We employ a tight-binding parametrization based on the Slater Koster model in\norder to fit the band structures of single-layer, bilayer and bulk black\nphosphorus obtained from first-principles calculations. We find that our model,\nwhich includes 9 or 17 parameters depending on whether overlap is included or\nnot, reproduces quite well the ab-initio band structures over a wide energy\nrange, especially the occupied bands. We also find that the inclusion of\noverlap parameters improves the quality of the fit for the conduction bands. On\nthe other hand, hopping and on-site energies are consistent throughout the\ndifferent systems, which is an indication that our model is suitable for\ncalculations on multilayer black phosphorus and more complex situations in\nwhich first-principles calculations become prohibitive, such as disordered\nsystems and heterostructures with a large lattice mismatch. We also discuss the\nlimitations of the model and how the fit procedure can be improved for a more\naccurate description of bands in the vicinity of the Fermi energy.",
        "positive": "Heat pump driven by the shot noise of a tunnel contact: We investigate a mechanism for cooling a lead based on a process that\nreplaces hot electrons by cold ones. The central idea is that a double quantum\ndot with an inhomogeneous Zeeman splitting acts as energy filter for the\ntransported electrons. The setup is such that hot electrons with spin up are\nremoved, while cold electrons with spin down are added. The required\nnon-equilibrium condition is provided by the capacitive coupling of one quantum\ndot to the shot noise of a strongly biased quantum point contact in the\ntunnelling limit. Special attention is paid to the identification of an\noperating regime in which the net electrical current vanishes."
    },
    {
        "anchor": "Magnetoplasmonic Enhancement of Faraday Rotation in Patterned Graphene\n  Metasurfaces: Faraday rotation is a fundamental property present in all non-reciprocal\noptical elements. In the THz range, graphene displays strong Faraday rotation;\nunfortunately, it is limited to frequencies below the cyclotron resonance. Here\nwe show experimentally that in specifically design metasurfaces,\nmagneto-plasmons can be used to circumvent this limitation. We find excellent\nagreement between theory and experiment and provide new physical insights and\npredictions on these phenomena. Finally, we demonstrate strong tuneability in\nthese metasurfaces using electric and magnetic field biasing.",
        "positive": "Generalized Master Equation Approach to Time-Dependent Many-Body\n  Transport: We recall theoretical studies on transient transport through interacting\nmesoscopic systems. It is shown that a generalized master equation (GME)\nwritten and solved in terms of many-body states provides the suitable formal\nframework to capture both the effects of the Coulomb interaction and\nelectron--photon coupling due to a surrounding single-mode cavity. We outline\nthe derivation of this equation within the Nakajima-Zwanzig formalism and point\nout technical problems related to its numerical implementation for more\nrealistic systems which can neither be described by non-interacting two-level\nmodels nor by a steady-state Markov-Lindblad equation. We first solve the GME\nfor a lattice model and discuss the dynamics of many-body states in a\ntwo-dimensional nanowire, the dynamical onset of the current-current\ncorrelations in electrostatically coupled parallel quantum dots and transient\nthermoelectric properties. Secondly, we rely on a continuous model to get the\nRabi oscillations of the photocurrent through a double-dot etched in a nanowire\nand embedded in a quantum cavity. A~many-body Markovian version of the GME for\ncavity-coupled systems is also presented."
    },
    {
        "anchor": "Coupled structural and magnetic properties of ferric fluoride\n  nanostructures part I: a Metropolis atomistic study: A modified Metropolis atomistic simulation is proposed to model the structure\nof grain boundaries (GBs) and interfaces in ionic nanostructured systems and is\napplied to the magnetically interesting case of iron trifluoride (FeF3). We\nchose long-range interatomic potentials adjusted on experimental results, and\nadapted a previously established Monte Carlo scheme consisting of various\nmodifications of the simulated annealing/ Metropolis algorithm. Atomic\nstructures of twisted and tilted GBs as a function of the relative\ndisorientation of the grains have been achieved yielding close to\nexperimentally measured properties. This approach takes into account the\nstructure of the grains far from the interface in order to constrain the\nrelative orientation of the grains, without any periodic boundary conditions.\nOne concludes that a long-range coulombic falloff of the interatomic potentials\nis necessary to obtain GB structures presenting a correct local topology but\nwith a smooth transition from crystalline to amorphous states. The structural\nfeatures are finally discussed in terms of topological aspects and local\nmagnetic structure.",
        "positive": "Renormalization Group Approach for the Wave Packet Dynamics in\n  Golden-Mean and Silver-Mean Labyrinth Tilings: We study the quantum diffusion in quasiperiodic tight-binding models in one,\ntwo, and three dimensions. First, we investigate a class of one-dimensional\nquasiperiodic chains, in which the atoms are coupled by weak and strong bonds\naligned according to the metallic-mean sequences. The associated generalized\nlabyrinth tilings in d dimensions are then constructed from the direct product\nof d such chains, which allows us to consider rather large systems numerically.\nThe electronic transport is studied by computing the scaling behavior of the\nmean-square displacement of the wave packets with respect to the time. The\nresults reveal the occurrence of anomalous diffusion in these systems. By\nextending a renormalization group approach, originally proposed for the\ngolden-mean chain, we show also for the silver-mean chain as well as for the\nhigher-dimensional labyrinth tilings that in the regime of strong quasiperiodic\nmodulation the wave-packet dynamics are governed by the underlying\nquasiperiodic structure."
    },
    {
        "anchor": "The Single-Electron-Box and the Helicity Modulus of an inverse square\n  XY-Model: We calculate the average number of electrons on a metallic\nsingle-electron-box as a function of the gate voltage for arbitrary values of\nthe tunneling conductance. In the vicinity of the plateaus the problem is\nequivalent to calculating the helicity modulus of a classical inverse square\nXY-model in one dimension. By a combination of perturbation theory, a two-loop\nrenormalization group calculation and a Monte-Carlo simulation in the\nintermediate regime we provide a complete description of the smearing of the\nCoulomb staircase at zero temperature with increasing conductance.",
        "positive": "Two-electron quantum dot molecule: Composite particles and the spin\n  phase diagram: We study a two-electron quantum dot molecule in a magnetic field by the\ndirect diagonalization of the Hamiltonian matrix. The ground states of the\nmolecule with the total spin S=0 and S=1 provide a possible realization for a\nqubit of a quantum computer. Switching between the states is best achieved by\nchanging the magnetic field. Based on an analysis of the wave function, we show\nthat the system consists of composite particles formed by an electron and flux\nquanta attached to it. This picture can also be used to explain the spin phase\ndiagram."
    },
    {
        "anchor": "Violation of detailed balance for charge-transfer statistics in\n  Coulomb-blockade systems: We discuss the possibility to generate in Coulomb-blockade systems steady\nstates that violate detailed balance. This includes both voltage biased and\nnon-biased scenarios. The violation of detailed balance yields that the\ncharge-transfer statistics for electrons tunneling into an island experiencing\nstrong Coulomb interaction is different from the statistics for tunneling out.\nThis can be experimentally tested by time-resolved measurement of the island's\ncharge state. We demonstrate this claim for two model systems.",
        "positive": "Optical conductivity of the threefold Hopf semimetal: A multifold Hopf semimetal is a topological point node semimetal possessing\nan anisotropy in the internal electronic structure, e.g., the dipole structure\nof the Berry curvature. In this paper, the unique features of threefold Hopf\nsemimetals in terms of the optical conductivity are theoretically investigated\nwith a minimal theoretical model by using linear response theory for a linearly\npolarized photon. The frequency spectrum of the optical conductivity shows an\nanisotropic dependence on the polarization angle of the incident photon even if\nthe electronic band structure is completely isotropic. The longitudinal optical\nconductivity linearly depends on the photon frequency and possesses step-like\nchanges in the frequency spectrum. The anisotropic electronic structure has a\nvarying the number of steps with the orientation of the photon polarization\naxis. We reveal that the anisotropy is attributed to symmetries preserving the\npoint node in threefold Hopf semimetals. The linearly polarized photon also\ninduces a Hall current but it vanishes with the photon polarization axis\nparallel to the Berry dipole axis. The numerical calculations show that these\ncharacteristic features can be observed even with a non-zero temperature and\ndisorder."
    },
    {
        "anchor": "Photovoltaic Hall effect in two-dimensional electron gas: Kinetic theory: We study theoretically transverse photoconductivity induced by circularly\npolarized radiation, i.e. the photovoltaic Hall effect, and linearly polarized\nradiation causing intraband optical transitions in two-dimensional electron gas\n(2DEG). We develop a microscopic theory of these effects based on analytical\nsolution of the Boltzmann equation for arbitrary electron spectrum and\nscattering mechanism. We calculate the transverse photoconductivity of 2DEG\nwith parabolic and linear dispersion for short-range and Coulomb scatterers at\ndifferent temperatures. We show that the transverse electric current is\nsignificantly enhanced at frequencies comparable to the inverse energy\nrelaxation time, whereas at higher frequencies the excitation spectrum and the\ndirection of current depend on the scattering mechanism. We also analyse the\neffect of thermalization processes caused by electron-electron collisions on\nthe photoconductivity.",
        "positive": "Conductance of the single-electron transistor: A comparison of\n  experimental data with Monte Carlo calculations: We report on experimental results for the conductance of metallic\nsingle-electron transistors as a function of temperature, gate voltage and\ndimensionless conductance. In contrast to previous experiments our transistor\nlayout allows for a direct measurement of the parallel conductance and no ad\nhoc assumptions on the symmetry of the transistors are necessary. Thus we can\nmake a comparison between our data and theoretical predictions without any\nadjustable parameter. Even for rather weakly conducting transistors significant\ndeviations from the perturbative results are noted. On the other hand, path\nintegral Monte Carlo calculations show remarkable agreement with experiments\nfor the whole range of temperatures and conductances."
    },
    {
        "anchor": "Noise-induced phase transition in the electronic Mach-Zehnder\n  interferometer: We consider dephasing in the electronic Mach-Zehnder interferometer strongly\ncoupled to current noise created by a voltage biased quantum point contact\n(QPC). We find the visibility of Aharonov-Bohm oscillations as a function\nvoltage bias and express it via the cumulant generating function of noise. In\nthe large-bias regime, high-order cumulants of current add up to cancel the\ndilution effect of a QPC. This leads to an abrupt change in the dependence of\nthe visibility on voltage bias which occurs at the QPC's transparency T=1/2.\nQuantum fluctuations in the vicinity of this point smear out the sharp\ntransition.",
        "positive": "Aharonov-Bohm oscillations caused by non-topological surface states in\n  Dirac nanowires: One intriguing fingerprint of surface states in topological insulators is the\nAharonov-Bohm effect in magnetoconductivity of nanowires. We show that surface\nstates in nanowires of Dirac materials (bismuth, bismuth antimony, and lead tin\nchalcogenides) being in non-topological phase, exhibit the same effect as\namendment to magnetoconductivity of the bulk states. We consider a simple model\nof a cylindrical nanowire, which is described by the 3D Dirac equation with a\ngeneral $T$-invariant boundary condition. The boundary condition is determined\nby a single phenomenological parameter whose sign defines topological-like and\nnon-topological surface states. The non-topological surface states emerge\noutside the gap. In longitudinal magnetic field $B$ they lead to Aharonov-Bohm\namendment for the density of states and correspondingly for conductivity of the\nnanowire. The phase of these magnetooscillations increases with $B$ from $\\pi$\nto $2\\pi$."
    },
    {
        "anchor": "Superfluidity of $^4$He Confined in Nano-Porous Media: We have examined superfluid properties of $^4$He confined to a nano-porous\nGelsil glass that has nanopores 2.5 nm in diameter. The pressure-temperature\nphase diagram was determined by torsional oscillator, heat capacity and\npressure studies. The superfluid transition temperature $T_{\\mathrm c}$\napproaches zero at 3.4 MPa, indicating a novel \"quantum\" superfluid transition.\nBy heat capacity measurements, the nonsuperfluid phase adjacent to the\nsuperfluid and solid phases is identified to be a nanometer-scale, localized\nBose condensation state, in which global phase coherence is destroyed. At high\npressures, the superfluid density has a $T$-linear term, and $T_{\\mathrm c}$ is\nproportional to the zero-temperature superfluid density. These results strongly\nsuggest that phase fluctuations in the superfluid order parameter play a\ndominant role on the phase diagram and superfluid properties.",
        "positive": "Cooling Torsional Nanomechanical Vibration by Spin-Orbit Interactions: We propose and study a spin-orbit interaction based mechanism to actively\ncool down the torsional vibration of a nanomechanical resonator made by\nsemiconductor materials. We show that the spin-orbit interactions of electrons\ncan induce a coherent coupling between the electron spins and the torsional\nmodes of nanomechanical vibration. This coherent coupling leads to an active\ncooling for the torsional modes via the dynamical thermalization of the\nresonator and the spin ensemble."
    },
    {
        "anchor": "Domain wall magneto-Seebeck effect: The interplay between charge, spin, and heat currents in magnetic nano\nsystems subjected to a temperature gradient has lead to a variety of novel\neffects and promising applications studied in the fast-growing field of\nspincaloritronics. Here we explore the magnetothermoelectrical properties of an\nindividual magnetic domain wall in a permalloy nanowire. In thermal gradients\nof the order of few Kelvin per micrometer along the long wire axis, we find a\nclear magneto-Seebeck signature due to the presence of a single domain wall.\nThe observed domain wall magneto-Seebeck effect can be explained by the\nmagnetization-dependent Seebeck coefficient of permalloy in combination with\nthe local spin configuration of the domain wall.",
        "positive": "Electronic Structures of Porous Nanocarbons: We use large scale ab-initio calculations to describe electronic structures\nof graphene, graphene nanoribbons, and carbon nanotubes periodically perforated\nwith nanopores. We disclose common features of these systems and develop a\nunified picture that permits us to analytically predict and systematically\ncharacterize metal-semiconductor transitions in nanocarbons with superlattices\nof nanopores of different sizes and types. These novel materials with highly\ntunable band structures have numerous potential applications in electronics,\nlight detection, and molecular sensing."
    },
    {
        "anchor": "Electron-induced nuclear magnetic ordering in n-type semiconductors: Nuclear magnetism in n-doped semiconductors with positive hyperfine constant\nis revisited. Two kinds of nuclear magnetic ordering can be induced by resident\nelectrons in a deeply cooled nuclear spin system. At positive nuclear spin\ntemperature below a critical value, randomly oriented nuclear spin polarons\nsimilar to that predicted by I. Merkulov [I. Merkulov, Physics of the Solid\nState 40, 930 (1998)] should emerge. These polarons are oriented randomly and\nwithin each polaron nuclear and electron spins are aligned\nantiferromagnetically. At negative nuclear spin temperature below a critical\nvalue we predict another type of magnetic ordering - dynamically induced\nnuclear ferromagnet. This is a long-range ferromagnetically ordered state\ninvolving both electrons and nuclei. It can form if electron spin relaxation is\ndominated by the hyperfine coupling, rather than by the spin-orbit interaction.\nApplication of the theory to the n-doped GaAs suggests that the ferromagnetic\norder may be reached at experimentally achievable nuclear spin temperature\n$\\Theta_N \\approx 0.5$ $\\mu$K and lattice temperature $T_L \\approx 5$ K.",
        "positive": "Gate-tunable imbalanced Kane-Mele model in encapsulated bilayer\n  jacutingaite: We study free, capped and encapsulated bilayer jacutingaite Pt$_2$HgSe$_3$\nfrom first principles. While the free standing bilayer is a large gap trivial\ninsulator, we find that the encapsulated structure has a small trivial gap due\nto the competition between sublattice symmetry breaking and\nsublattice-dependent next-nearest-neighbor hopping. Upon the application of a\nsmall perpendicular electric field, the encapsulated bilayer undergoes a\ntopological transition towards a quantum spin Hall insulator. We find that this\ntopological transition can be qualitatively understood by modeling the two\nlayers as uncoupled and described by an imbalanced Kane-Mele model that takes\ninto account the sublattice imbalance and the corresponding inversion-symmetry\nbreaking in each layer. Within this picture, bilayer jacutingaite undergoes a\ntransition from a 0+0 state, where each layer is trivial, to a 0+1 state, where\nan unusual topological state relying on Rashba-like spin orbit coupling emerges\nin only one of the layers."
    },
    {
        "anchor": "Size-dependence of Strong-Coupling Between Nanomagnets and Photonic\n  Cavities: The coherent dynamics of a coupled photonic cavity and a nanomagnet is\nexplored as a function of nanomagnet size. For sufficiently strong coupling\neigenstates involving highly entangled photon and spin states are found, which\ncan be combined to create coherent states. As the size of the nanomagnet\nincreases its coupling to the photonic mode also monotonically increases, as\nwell as the number of photon and spin states involved in the system's\neigenstates. For small nanomagnets the crystalline anisotropy of the magnet\nstrongly localized the eigenstates in photon and spin number, quenching the\npotential for coherent states. For a sufficiently large nanomagnet the\nmacrospin approximation breaks down and different domains of the nanomagnet may\ncouple separately to the photonic mode. Thus the optimal nanomagnet size is\njust below the threshold for failure of the macrospin approximation.",
        "positive": "Stabilization of single-electron pumps by high magnetic fields: We study the effect of perpendicular magnetic fields on a single-electron\nsystem with a strongly time-dependent electrostatic potential. Continuous\nimprovements to the current quantization in these electron pumps are revealed\nby high-resolution measurements. Simulations show that the sensitivity of\ntunnel rates to the barrier potential is enhanced, stabilizing particular\ncharge states. Nonadiabatic excitations are also suppressed due to a reduced\nsensitivity of the Fock-Darwin states to electrostatic potential. The\ncombination of these effects leads to significantly more accurate current\nquantization."
    },
    {
        "anchor": "Mixed-order symmetry-breaking quantum phase transition far from\n  equilibrium: We study the current-carrying steady-state of a transverse field Ising chain\ncoupled to magnetic thermal reservoirs and obtain the non-equilibrium phase\ndiagram as a function of the magnetization potential of the reservoirs. Upon\nincreasing the magnetization bias we observe a discontinuous jump of the\nmagnetic order parameter that coincides with a divergence of the correlation\nlength. For steady-states with a non-vanishing conductance, the entanglement\nentropy at zero temperature displays a bias dependent logarithmic correction\nthat violates the area law and differs from the well-known equilibrium case.\nOur findings show that out-of-equilibrium conditions allow for novel critical\nphenomena not possible at equilibrium.",
        "positive": "Radiation-induced magnetoresistance oscillations in two-dimensional\n  electron systems under bichromatic irradiation: We analyze the magnetoresistance $R_{xx}$ oscillations in high-mobility\ntwo-dimensional electron systems induced by the combined driving of two\nradiation fields of frequency $\\omega_1$ and $\\omega_2$, based on the\nbalance-equation approach to magnetotransport for high-carrier-density systems\nin Faraday geometry. It is shown that under bichromatic irradiation of\n$\\omega_2\\sim 1.5 \\omega_1$, most of the characterstic peak-valley pairs in the\ncurve of $R_{xx}$ versus magnetic field in the case of monochromatic\nirradiation of either $\\omega_1$ or $\\omega_2$ disappear, except the one around\n$\\omega_1/\\omega_c\\sim 2$ or $\\omega_2/\\omega_c\\sim 3$. $R_{xx}$ oscillations\nshow up mainly as new peak-valley structures around other positions related to\nmultiple photon processes of mixing frequencies $\\omega_1+\\omega_2$,\n$\\omega_2-\\omega_1$, etc. Many minima of these resistance peak-valley pairs can\ndescend down to negative with enhancing radiation strength, indicating the\npossible bichromaticzero-resistance states."
    },
    {
        "anchor": "Ultrabright single-photon source on diamond with electrical pumping: The recently demonstrated electroluminescence of color centers in diamond\nmakes them one of the best candidates for room temperature single-photon\nsources. However, the reported emission rates are far off what can be achieved\nby state-of-the-art electrically driven epitaxial quantum dots. Since the\nelectroluminescence mechanism has not yet been elucidated, it is not clear to\nwhat extent the emission rate can be increased. Here we develop a theoretical\nframework to study single-photon emission from color centers in diamond under\nelectrical pumping. The proposed model comprises electron and hole trapping and\nreleasing, transitions between the ground and excited states of the color\ncenter as well as structural transformations of the center due to carrier\ntrapping. It provides the possibility to predict both the photon emission rate\nand the wavelength of emitted photons. Self-consistent numerical simulations of\nthe single-photon emitting diode based on the proposed model show that the\nphoton emission rate can be as high as 100 kcounts s$^{-1}$ at standard\nconditions. In contrast to most optoelectronic devices, the emission rate\nsteadily increases with the device temperature achieving of more than 100\nMcount s$^{-1}$ at 500 K, which is highly advantageous for practical\napplications. These results demonstrate the potential of color centers in\ndiamond as electrically driven non-classical light emitters and provide a\nfoundation for the design and development of single-photon sources for optical\nquantum computation and quantum communication networks operating at room and\nhigher temperatures.",
        "positive": "Intrinsic Magnetic Topological Materials: Topological states of matter possess bulk electronic structures categorized\nby topological invariants and edge/surface states due to the bulk-boundary\ncorrespondence. Topological materials hold great potential in the development\nof dissipationless spintronics, information storage, and quantum computation,\nparticularly if combined with magnetic order intrinsically or extrinsically.\nHere, we review the recent progress in the exploration of intrinsic magnetic\ntopological materials, including but not limited to magnetic topological\ninsulators, magnetic topological metals, and magnetic Weyl semimetals. We pay\nspecial attention to their characteristic band features such as the gap of\ntopological surface state, gapped Dirac cone induced by magnetization (either\nbulk or surface), Weyl nodal point/line, and Fermi arc, as well as the exotic\ntransport responses resulting from such band features. We conclude with a brief\nenvision for experimental explorations of new physics or effects by\nincorporating other orders in intrinsic magnetic topological materials."
    },
    {
        "anchor": "Photonic band structure and effective medium properties of\n  doubly-resonant core-shell metallo-dielectric nanowire arrays: low-loss,\n  isotropic optical negative-index behavior: We investigate theoretically and numerically the photonic band structure in\nthe optical domain of an array of core-shell metal-semiconductor nanowires.\nCorresponding negative-index photonic bands are calculated, showing isotropic\nequifrequency surfaces. The effective (negative) electric permittivity and\nmagnetic permeability, retrieved from S parameters, are used to compare the\nperformance of such nanowire arrays with homogeneous media in canonical\nexamples, such as refraction through a prism and flat-lens focusing. Very good\nagreement is found, indeed confirming the effective medium behavior of the\nnanowire array as a low-loss, isotropic (2D) and bulk, optical negative index\nmetamaterial. Indeed, disorder is introduced to further stress its robustness",
        "positive": "Disordered Dirac Fermions: the Marriage of Three Different Approaches: We compare the critical multipoint correlation functions for two-dimensional\n(massless) Dirac fermions in the presence of a random su(N) (non-Abelian) gauge\npotential, obtained by three different methods. We critically reexamine\nprevious results obtained using the replica approach and in the limit of\ninfinite disorder strength and compare them to new results (presented here)\nobtained using the supersymmetric approach to the N=2 case. We demonstrate that\nthis menage a trois of different approaches leads to identical results.\nRemarkable relations between apparently different conformal field theories\n(CFTs) are thereby obtained. We further establish a connection between the\nrandom Dirac fermion problem and the c=-2 theory of dense polymers. The\npresence of the c=-2 theory may be seen in all three different treatments of\nthe disorder."
    },
    {
        "anchor": "Giant non-linear susceptibility of hydrogenic donors in silicon and\n  germanium: Implicit summation is a technique for the conversion of sums over\nintermediate states in multiphoton absorption and the high-order susceptibility\nin hydrogen into simple integrals. Here, we derive the equivalent technique for\nhydrogenic impurities in multi-valley semiconductors. While the absorption has\nuseful applications, it is primarily a loss process; conversely, the non-linear\nsusceptibility is a crucial parameter for active photonic devices. For Si:P, we\npredict the hyperpolarizability ranges from $\\chi^{(3)}/n_{\\text{3D}}=2.9 $ to\n$580 \\times 10^{-38}$ $\\text{m}^5/\\text{V}^2$ depending on the frequency, even\nwhile avoiding resonance. Using samples of a reasonable density,\n$n_{\\text{3D}}$, and thickness, $L$, to produce third-harmonic generation at 9\nTHz, a frequency that is difficult to produce with existing solid-state\nsources, we predict that $\\chi^{(3)}$ should exceed that of bulk InSb and\n$\\chi^{(3)}L$ should exceed that of graphene and resonantly enhanced quantum\nwells.",
        "positive": "Fast quantum limited read-out of a superconducting qubit using a slow\n  oscillator: We describe how to perform fast quantum limited read-out of a solid state\nqubit biased at its degeneracy point. The method is based on homodyne detection\nof the phase of a microwave signal reflected by a slow oscillator coupled to\nthe qubit. Analyzing the whole quantum read-out process, we find that the\ndetection is indeed quantum limited and that this limit may be reached even\nusing a resonance circuit with a low quality factor, thus enabling the use of\nshort measurement pulses. As an example, we discuss in detail the read-out of a\nCooper-pair box capacitively coupled to a lumped element LC-oscillator.\nFurthermore, we give formulas for the backaction while not measuring, and\ndiscuss optimal parameters for a realistic design capable of fast (~50 ns)\nsingle-shot read-out."
    },
    {
        "anchor": "Spin waves in planar quasicrystal of Penrose tiling: We investigated two-dimensional magnonic structures which are the\ncounterparts of photonic quasicrystals forming Penrose tiling. We considered\nthe slab composed of Ni (or Py) disks embedded in Fe (or Co) matrix. The disks\nwere arranged in quasiperiodic Pernose-like structure. The infinite\nquasicrystal was approximated by its rectangular section with periodic boundary\nconditions applied. This approach allowed us to use the plane wave method to\nfind the frequency spectrum of eigenmodes for spin waves and their spatial\nprofiles. The calculated integrated density of states shows more distictive\nmagnonic gaps for the structure composed of materials of high magnetic contrast\n(Ni and Fe) and relatively high filling fraction. This proves the impact of\nquasiperiodic long-range order on the spectrum of spin waves. We also\ninvestigated the localization of SW eingenmodes resulting from the\nquasipeiodicity of the structure.",
        "positive": "Spin transfer torque in continuous textures: semiclassical Boltzmann\n  approach: We consider a microscopic model of itinerant electrons coupled via\nferromagnetic exchange to a local magnetization whose direction vector n(r,t)\nvaries in space and time. We assume that to first order in the spatial gradient\nand time derivative of n(r,t) the magnetization distribution function f(p,r,t)\nof itinerant electrons has the Ansatz form: f(p,r,t)=f_{parallel}(p)n(r,t)+\nf_{1 r}(p) n ^ nabla_{r} n+f_{2 r}(p) nabla_{r} n+ f_{1 t}(p) n ^ partial_t\nn+f_{2 t}(p) partial_t n. Using then the Landau-Sillin equations of motion\napproach we derive explicit forms for the components f_{parallel}(p), f_{1\nr}(p), f_{2 r}(p), f_{1 t}(p) and f_{2 t}(p) in \"equilibrum\" and in out of\nequilibrum situations for: (i) no scattering by impurities, (ii) spin\nconserving scattering and (iii) spin non-conserving scattering. The back action\non the localized electron magnetization from the out of equilibrum part of the\ntwo components f_{1 r}, f_{2 r} constitutes the two spin transfer torque terms."
    },
    {
        "anchor": "Tunable plasmonic reflection by bound 1D electron states in a 2D Dirac\n  metal: We show that surface plasmons of a two-dimensional Dirac metal such as\ngraphene can be reflected by line-like perturbations hosting one-dimensional\nelectron states. The reflection originates from a strong enhancement of the\nlocal optical conductivity caused by optical transitions involving these bound\nstates. We propose that the bound states can be systematically created,\ncontrolled, and liquidated by an ultranarrow electrostatic gate. Using infrared\nnanoimaging, we obtain experimental evidence for the locally enhanced\nconductivity of graphene induced by a carbon nanotube gate, which supports this\ntheoretical concept.",
        "positive": "Electrical switching and interferometry of massive Dirac particles in\n  topological insulators constrictions: We investigate the electrical switching of charge and spin transport in a\ntopological insulator nanoconstriction in a four terminal device. The switch of\nthe edge channels is caused by the coupling between edge states which overlap\nin the constriction and by the tunneling effects at the contacts and therefore\ncan be manipulated by tuning the applied voltages on the split-gate or by\ngeometrical etching. The switching mechanism can be conveniently studied by\nelectron interferometry involving the measurements of the current in different\nconfigurations of the side gates, while the applied bias from the external\nleads can be tuned to obtain pure charge or pure spin currents (charge- and\nspin- bias configurations). Relevant signatures of quantum confinement effects,\nquantum size effects and energy gap are evident in the Fabry-Perot physics of\nthe device allowing for a full characterization of the charge and spin\ncurrents. The proposed electrical switching behavior offers an efficient tool\nto manipulate topological edge state transport in a controllable way."
    },
    {
        "anchor": "Analysis of integrated single-electron memory operation: Various aspects of single-electron memory are discussed. In particular, we\nanalyze the single-electron charging by Fowler-Nordheim tunneling, propose the\nidea of background charge compensation, and discuss the defect-tolerant\narchitecture based on nanofuses.",
        "positive": "Inducing an Incipient Terahertz Finite Plasmonic Crystal in Coupled Two\n  Dimensional Plasmonic Cavities: We measured a change in the current transport of an antenna-coupled,\nmulti-gate, GaAs/AlGaAs field-effect transistor when terahertz electromagnetic\nwaves irradiated the transistor and attribute the change to bolometric heating\nof the electrons in the two-dimensional electron channel. The observed\nterahertz absorption spectrum indicates coherence between plasmons excited\nunder adjacent biased device gates. The experimental results agree\nquantitatively with a theoretical model we developed that is based on a\ngeneralized plasmonic transmission line formalism and describes an evolution of\nthe plasmonic spectrum with increasing electron density modulation from\nhomogeneous to the crystal limit. These results demonstrate an electronically\ninduced and dynamically tunable plasmonic band structure."
    },
    {
        "anchor": "Black Hole Horizon in a Type-III Dirac Semimetal Zn$_2$In$_2$S$_5$: Recently, realizing new fermions, such as type-I and type-II Dirac/Weyl\nfermions in condensed matter systems, has attracted considerable attention.\nHere we show that the transition state from type-I to type-II Dirac fermions\ncan be viewed as a type-III Dirac fermion, which exhibits unique\ncharacteristics, including a Dirac-line Fermi surface with nontrivial\ntopological invariant and critical chiral anomaly effect, distinct from\npreviously known Dirac semimetals. Most importantly, we discover\nZn$_2$In$_2$S$_5$ is a type-III Dirac semimetal material, characterized with a\npair of Dirac points in the bulk and Fermi arcs on the surface. We further\npropose a solid-state realization of the black-hole-horizon analogue in\ninhomogeneous Zn$_2$In$_2$S$_5$ to simulate black hole evaporation with high\nHawking temperature. We envision that our findings will stimulate researchers\nto study novel physics of type-III Dirac fermions, as well as astronomical\nproblems in a condensed matter analogue.",
        "positive": "Spin-resolved dynamical conductance of correlated large-spin magnetic\n  molecules: The finite-frequency transport properties of a large-spin molecule attached\nto ferromagnetic contacts are studied theoretically in the Kondo regime. The\nfocus is on the behavior of the dynamical conductance in the linear response\nregime, which is determined by using the numerical renormalization group\nmethod. It is shown that the dynamical conductance depends greatly on the\nmagnetic configuration of the device and intrinsic parameters of the molecule.\nIn particular, conductance exhibits characteristic features for frequencies\ncorresponding to the dipolar and quadrupolar exchange fields resulting from the\npresence of spin-dependent tunneling. Moreover, a dynamical spin accumulation\nin the molecule, associated with the off-diagonal-in-spin component of the\nconductance, is predicted. This spin accumulation becomes enhanced with\nincreasing the spin polarization of the leads, and it results in a nonmonotonic\ndependence of the conductance on frequency, with local maxima occurring for\ncharacteristic energy scales."
    },
    {
        "anchor": "Zero-Momentum Cyclotron Spin-Flip Mode in a Spin-Unpolarized Quantum\n  Hall System: We report on a study of the zero-momentum cyclotron spin-flip excitation in\nthe V=2 quantum Hall regime. Using the excitonic representation the excitation\nenergy is calculated up to the second order Coulomb corrections. A considerable\nnegative exchange shift relative to the cyclotron gap is established for\ncyclotron spin-flip excitations in the the spin-unpolarized electronic system.\nUnder these conditions this type of states presents the {\\it lowest-energy}\nexcitations. For a fixed filling factor V=2 the energy shift is independent of\nthe magnetic field which is in agreement with recent experimental observations.",
        "positive": "Charge and Spin Currents Generated by Dynamical Spins: We demonstrate theoretically that a charge current and a spin current are\ngenerated by spin dynamics in the presence of spin-orbit interaction in the\nperturbative regime. We consider a general spin-orbit interaction including the\nspatially inhomogeneous case. Spin current due to spin damping is identified as\none origin of generated charge current, but other contributions exist, such as\nthe one due to an induced conservative field and the one arising from the\ninhomogeneity of spin-orbit interaction."
    },
    {
        "anchor": "Stimulated quantum phase slips from weak electromagnetic radiations in\n  superconducting nanowires: We study the rate of quantum phase slips in an ultranarrow superconducting\nnanowire exposed to weak electromagnetic radiations. The superconductor is in\nthe dirty limit close to the superconducting-insulating transition, where\nfluxoids move in strong dissipation. We use a semiclassical approach and show\nthat external radiation stimulates a significant enhancement in the probability\nof quantum phase slips. This can help to outline a new type of detector for\nmicrowave to submillimetre radiations based on stimulated quantum phase slip\nphenomenon.",
        "positive": "Spinor-dominated magnetoresistance driven by the topological phase\n  transition in $\u03b2$-Ag$_2$Se: A topological insulator is a quantum material which possesses conducting\nsurfaces and an insulating bulk. Despite extensive researches on the properties\nof Dirac surface states, the characteristics of bulk states have remained\nlargely unexplored. Here we report the observation of spinor-dominated\nmagnetoresistance anomalies in the topological insulator $\\beta $-Ag$_2$Se,\ninduced by a magnetic-field-driven band topological phase transition. These\nanomalies are caused by intrinsic orthogonality in the wave-function spinors of\nthe last Landau bands of the bulk states, in which backscattering is strictly\nforbidden during a band topological phase transition. This new type of\nlongitudinal magnetoresistance, purely controlled by the wave-function spinors\nof the last Landau bands, highlights a unique signature of electrical transport\naround the band topological phase transition. With further reducing the quantum\nlimit and gap size in $\\beta $-Ag$_2$Se, our results may also suggest possible\ndevice applications based on this spinor-dominated mechanism and signify a rare\ncase where topology enters the realm of magnetoresistance control."
    },
    {
        "anchor": "High-order Harmonic Generation and Dynamic Localization in a driven\n  two-level system, a non-perturbative solution using the Floquet-Green\n  formalism: We apply the Floquet-Green operator formalism to the case of a\nharmonically-driven two-level system. We derive exact expressions for the\nquasi-energies and the components of the Floquet eigenstates with the use of\ncontinued fractions. We study the avoided crossings structure of the\nquasi-energies as a function of the strength of the driving field and give an\ninterpretation in terms of resonant multi-photon processes. From the Floquet\neigenstates we obtain the time-evolution operator. Using this operator we study\nDynamic Localization and High-order Harmonic Generation in the non-perturbative\nregime.",
        "positive": "Scattering Theory Approach to Inelastic Transport in Nanoscale Systems: We present a scattering-state description for the non-equilibrium\nmultichannel charge transport in the presence of electron-vibration couplings.\nIt is based on an expansion of scattering orders of eigenchannel states.\nExamining charge transitions between scattering states, we clarifies competing\ninelastic and elastic scattering processes, and compare with the interpretation\nbased on the non-equilibrium Green's functions formalism. We also derive a\ngeneral expression for conductance variations in single-channel systems. It\nprovides a comprehensive picture for the variation including the well-known\nresult, the 0.5 rule, from the aspect of interplay between elastic and\ninelastic scattering processes."
    },
    {
        "anchor": "Unified description of the optical phonon modes in $N$-layer MoTe$_2$: $N$-layer transition metal dichalcogenides provide a unique platform to\ninvestigate the evolution of the physical properties between the bulk (three\ndimensional) and monolayer (quasi two-dimensional) limits. Here, using\nhigh-resolution micro-Raman spectroscopy, we report a unified experimental\ndescription of the $\\Gamma$-point optical phonons in $N$-layer $2H$-molybdenum\nditelluride (MoTe$_2$). We observe a series of $N$-dependent low-frequency\ninterlayer shear and breathing modes (below $40~\\rm cm^{-1}$, denoted LSM and\nLBM) and well-defined Davydov splittings of the mid-frequency modes (in the\nrange $100-200~\\rm cm^{-1}$, denoted iX and oX), which solely involve\ndisplacements of the chalcogen atoms. In contrast, the high-frequency modes (in\nthe range $200-300~\\rm cm^{-1}$, denoted iMX and oMX), arising from\ndisplacements of both the metal and chalcogen atoms, exhibit considerably\nreduced splittings. The manifold of phonon modes associated with the in-plane\nand out-of-plane displacements are quantitatively described by a force constant\nmodel, including interactions up to the second nearest neighbor and surface\neffects as fitting parameters. The splittings for the iX and oX modes observed\nin $N$-layer crystals are directly correlated to the corresponding bulk Davydov\nsplittings between the $E_{2u}/E_{1g}$ and $B_{1u}/A_{1g}$ modes, respectively,\nand provide a measurement of the frequencies of the bulk silent $E_{2u}$ and\n$B_{1u}$ optical phonon modes. Our analysis could readily be generalized to\nother layered crystals.",
        "positive": "High-mobility, wet-transferred graphene grown by chemical vapor\n  deposition: We report high room-temperature mobility in single layer graphene grown by\nChemical Vapor Deposition (CVD) after wet transfer on SiO$_2$ and hexagonal\nboron nitride (hBN) encapsulation. By removing contaminations trapped at the\ninterfaces between single-crystal graphene and hBN, we achieve mobilities up\nto$\\sim70000cm^2 V^{-1} s^{-1}$ at room temperature and$\\sim120000cm^2 V^{-1}\ns^{-1}$ at 9K. These are over twice those of previous wet transferred graphene\nand comparable to samples prepared by dry transfer. We also investigate the\ncombined approach of thermal annealing and encapsulation in polycrystalline\ngraphene, achieving room temperature mobilities$\\sim30000 cm^2 V^{-1} s^{-1}$.\nThese results show that, with appropriate encapsulation and cleaning, room\ntemperature mobilities well above $10000cm^2 V^{-1} s^{-1}$ can be obtained in\nsamples grown by CVD and transferred using a conventional, easily scalable\nPMMA-based wet approach."
    },
    {
        "anchor": "Hinged Quantum Spin-Hall Effect in Antiferromagnetic Topological\n  Insulators: In this work, we predict a hinged quantum spin-Hall (HQSH) effect featured by\na pair of helical hinge modes in antiferromagnetic (AFM) topological insulator\n(TI) multilayers. This pair of helical hinge modes are localized on the hinges\nof the top and bottom surfaces of the AFM TI multilayers. Unlike the\nconventional QSH effect, the HQSH effect survives the breaking of time-reversal\nsymmetry (TRS) and thus represents a different kind of topological phenomenon.\nThe helical hinge modes are sustainable to inelastic scattering and\nTRS-breaking disorder, which can be observed in macroscopic samples. We show\nthat this HQSH effect can be understood as a three-dimensional generalization\nof the Su-Schrieffer-Heeger model and its topology is characterized by the spin\nChern number. At last, we propose that the HQSH effect can be realized in newly\nfound intrinsic AFM TI materials (MnBi$_2$Te$_4$)$_m$(Bi$_2$Te$_3$)$_n$ or\nmagnetic-doped TI multilayers by current experimental setups.",
        "positive": "Observation of drift and diffusion processes in Ti/TiOx/Ti memristive\n  devices prepared by local anodic oxidation: We demonstrate that memristive devices can be fabricated by tip-induced\noxidation of thin metallic films using atomic force microscope. Electrical\nmeasurements of such prepared Ti/TiOx/Ti test structures confirmed their\nmemristive behavior and inferred diffusion of oxygen vacancies in the TiOx\nbarrier. Consequent Kelvin probe force microscopy studies provided evidence for\nthe diffusion, as well as for expected oxygen vacancy drift. Time evolution of\nthe space distribution of the vacancies due to the diffusion process revealed\nminute-scale (at least) retention times of the devices. The work presents\ntechnology alternative for fabrication of memristive nanodevices in geometry\nfavouring advantageous scanning probe microscopy studies of their in-barrier\nprocesses, as well as widely utilizable approach to search for novel oxide\nmaterials for perspective memristive applications."
    },
    {
        "anchor": "Effective Tight-Binding Model of Compensated Ferrimagnetic Weyl\n  Semimetal with Spontaneous Orbital Magnetization: The effective tight-binding model with compensated ferrimagnetic\ninverse-Heusler lattice Ti$_{2}$MnAl, candidate material of magnetic Weyl\nsemimetal, is proposed. The energy spectrum near the Fermi level, the\nconfigurations of the Weyl points, and the anomalous Hall conductivity are\ncalculated. We found that the orbital magnetization is finite, while the total\nspin magnetization vanishes, at the energy of the Weyl points. The magnetic\nmoments at each site are correlated with the orbital magnetization, and can be\ncontrolled by the external magnetic field.",
        "positive": "Current Driven Domain Wall Depinning in Notched Permalloy Nanowires: In this work, we have investigated the domain wall (DW) depinning behavior in\nthe notched nanowire by a micromagnetic simulation. A transverse domain wall\n(TW) was initially positioned at the center of notch and 1 ns length current\npulse was applied to depin the DW with respect to the notch size s and the wire\nwidth variation. We have observed the depinning current density Jd which was a\nminimum current to escape DW from the notch. It was found that the depinning\ncurrent density decreased as the wire width and the notch size increased. In\nthe depinning process, we observed the inner structure of DW generally\ntransformed from TW to anti-vortex wall (AVW). Interestingly, for the case of s\nless than 70 nm, AVW formed and depinned closely to the period when current\npulse was active, while for s larger than 70 nm, AVW formed until the current\npulse went to zero and then depinned after flipped TW was formed. It can be\nexplained that the transformation of DW inner structures were affected by the\nspin torque energy and contributed to DW depinning behavior from the notched\nnanowires."
    },
    {
        "anchor": "Mode-Locking in Quantum-Hall-Effect Point Contacts: We study the effect of an ac drive on the current-voltage (I-V)\ncharacteristics of a tunnel junction between two fractional Quantum Hall fluids\nat filling $\\nu ^{-1}$ an odd integer. Within the chiral Luttinger liquid model\nof edge states, the point contact dynamics is described by a driven damped\nquantum mechanical pendulum. In a semi-classical limit which ignores electron\ntunnelling, this model exhibits mode-locking, which corresponds to current\nplateaus in the I-V curve at integer multiples of $I= e\\omega /2\\pi$, with\n$\\omega$ the ac drive angular frequency. By analyzing the full quantum model at\nnon-zero $\\nu$ using perturbative and exact methods, we study the effect of\nquantum fluctuation on the mode-locked plateaus. For $\\nu=1$ quantum\nfluctuations smear completely the plateaus, leaving no trace of the ac drive.\nFor $\\nu \\ge 1/2$ smeared plateaus remain in the I-V curve, but are not\ncentered at the currents $I=n e \\omega /2\\pi$. For $\\nu < 1/2$ rounded plateaus\ncentered around the quantized current values are found. The possibility of\nusing mode locking in FQHE point contacts as a current-to-frequency standard is\ndiscussed.",
        "positive": "Topological Phase Transitions Induced by Disorder in Magnetically Doped\n  (Bi, Sb)$_2$Te$_3$ Thin Films: We study disorder induced topological phase transitions in magnetically doped\n(Bi, Sb)$_2$Te$_3$ thin films, by using large scale transport simulations of\nthe conductance through a disordered region coupled to reservoirs in the\nquantum spin Hall regime. Besides the disorder strength, the rich phase diagram\nalso strongly depends on the magnetic exchange field, the Fermi level, and the\ninitial topological state in the undoped and clean limit of the films. In an\ninitially trivial system at non-zero exchange field, varying the disorder\nstrength can induce a sequence of transitions from a normal insulating, to a\nquantum anomalous Hall, then a spin-Chern insulating, and finally an Anderson\ninsulating state. While for a system with topology initially, a similar\nsequence, but only starting from the quantum anomalous Hall state, can be\ninduced. Varying the Fermi level we find a similarly rich phase diagram,\nincluding transitions from the quantum anomalous Hall to the spin-Chern\ninsulating state via a state that behaves as a mixture of a quantum anomalous\nHall and a metallic state, akin to recent experimental reports."
    },
    {
        "anchor": "Spin-Hall effect in two-dimensional mesoscopic hole systems: The spin Hall effect in two dimensional hole systems is studied by using the\nfour-terminal Landauer-B\\\"{u}ttiker formula with the help of Green functions.\nThe spin Hall effect exists even when there are {\\em not} any correlations\nbetween the spin-up and -down heavy holes (light holes) and when the\n$\\Gamma$-point degeneracy of the heavy hole and light hole bands is lifted by\nthe confinement or recovered by the strain. When only a heavy hole charge\ncurrent without any spin polarization is injected through one lead, under right\nchoice of lead voltages, one can get a pure heavy (light) hole spin current,\ncombined with a possible impure light (heavy) hole spin current from another\ntwo leads. The spin Hall coefficients of both heavy and light holes depend on\nthe Fermi energy, devise size and the disorder strength. It is also shown that\nthe spin Hall effect of two dimensional hole systems is much more robust than\nthat of electron systems with the Rashba spin-orbit coupling and the spin Hall\ncoefficients do not decrease with the system size but tend to some nonzero\nvalues when the disorder strength is smaller than some critical value.",
        "positive": "Time-Resolved Magnetic Relaxation of a Nanomagnet on Subnanosecond Time\n  Scales: We present a two-current-pulse temporal correlation experiment to study the\nintrinsic subnanosecond nonequilibrium magnetic dynamics of a nanomagnet during\nand following a pulse excitation. This method is applied to a model\nspin-transfer system, a spin valve nanopillar with perpendicular magnetic\nanisotropy. Two-pulses separated by a short delay (< 500 ps) are shown to lead\nto the same switching probability as a single pulse with a duration that\ndepends on the delay. This demonstrates a remarkable symmetry between magnetic\nexcitation and relaxation and provides a direct measurement of the magnetic\nrelaxation time. The results are consistent with a simple finite temperature\nFokker-Planck macrospin model of the dynamics, suggesting more coherent\nmagnetization dynamics in this short time nonequilibrium limit than near\nequilibrium."
    },
    {
        "anchor": "Graphene-based photovoltaic cells for near-field thermal energy\n  conversion: Thermophotovoltaic devices are energy-conversion systems generating an\nelectric current from the thermal photons radiated by a hot body. In far field,\nthe efficiency of these systems is limited by the thermodynamic\nSchockley-Queisser limit corresponding to the case where the source is a black\nbody. On the other hand, in near field, the heat flux which can be transferred\nto a photovoltaic cell can be several orders of magnitude larger because of the\ncontribution of evanescent photons. This is particularly true when the source\nsupports surface polaritons. Unfortunately, in the infrared where these systems\noperate, the mismatch between the surface-mode frequency and the semiconductor\ngap reduces drastically the potential of this technology. Here we show that\ngraphene-based hybrid photovoltaic cells can significantly enhance the\ngenerated power paving the way to a promising technology for an intensive\nproduction of electricity from waste heat.",
        "positive": "Spin-orbit-induced strong coupling of a single spin to a nanomechanical\n  resonator: We theoretically investigate the deflection-induced coupling of an electron\nspin to vibrational motion due to spin-orbit coupling in suspended carbon\nnanotube quantum dots. Our estimates indicate that, with current capabilities,\na quantum dot with an odd number of electrons can serve as a realization of the\nJaynes-Cummings model of quantum electrodynamics in the strong-coupling regime.\nA quantized flexural mode of the suspended tube plays the role of the optical\nmode and we identify two distinct two-level subspaces, at small and large\nmagnetic field, which can be used as qubits in this setup. The strong intrinsic\nspin-mechanical coupling allows for detection, as well as manipulation of the\nspin qubit, and may yield enhanced performance of nanotubes in sensing\napplications."
    },
    {
        "anchor": "Disorder in the non-linear anomalous Hall effect of\n  $\\mathcal{P}\\mathcal{T}$-symmetric Dirac fermions: The study of the non-linear anomalous Hall effect (NLAHE) in\n$\\mathcal{P}\\mathcal{T}$-symmetric systems has focussed on intrinsic\nmechanisms. Here we show that disorder contributes substantially to NLAHE and\noften overwhelms intrinsic terms. We identify terms to zeroth order in the\ndisorder strength involving the Berry curvature dipole, skew scattering and\nside-jump, all exhibiting a strong peak as a function of the Fermi energy, a\nsignature of interband coherence. Our results suggest NLAHE at experimentally\nrelevant transport densities in $\\mathcal{P}\\mathcal{T}$-symmetric systems is\nlikely to be extrinsic.",
        "positive": "Screening nearest-neighbor interactions in networks of exciton-polariton\n  condensates through spin orbit coupling: We study the modification of the spatial coupling parameter between\ninteracting ballistic exciton-polariton condensates in the presence of photonic\nspin orbit coupling appearing from TE-TM splitting in planar semiconductor\nmicrocavities. We propose a strategy to make the coupling strength between\nnext-nearest-neighbours stronger than between nearest-neighbour, which inverts\nthe conventional idea of the spatial coupling hierarchy between sites. Our\nstrategy relies on the dominantly populated high-momentum components in the\nballistic condensates which, in the presence of TE-TM splitting, lead to rapid\nradial precession of the polariton pseudospin. As a consequence, condensate\npairs experience distance-periodic screening of their interaction strength,\nseverely modifying their synchronization and condensation threshold solutions."
    },
    {
        "anchor": "Giant magnon spin conductivity approaching the two-dimensional transport\n  regime in ultrathin yttrium iron garnet films: Conductivities are key material parameters that govern various types of\ntransport (electronic charge, spin, heat etc.) driven by thermodynamic forces.\nMagnons, the elementary excitations of the magnetic order, flow under the\ngradient of a magnon chemical potential in proportion to a magnon (spin)\nconductivity $\\sigma_{m}$. The magnetic insulator yttrium iron garnet (YIG) is\nthe material of choice for efficient magnon spin transport. Here we report an\nunexpected giant $\\sigma_{m}$ in record-thin YIG films with thicknesses down to\n3.7 nm when the number of occupied two-dimensional (2D) subbands is reduced\nfrom a large number to a few, which corresponds to a transition from 3D to 2D\nmagnon transport. We extract a 2D spin conductivity ($\\approx1$ S) at room\ntemperature, comparable to the (electronic) spin conductivity of the\nhigh-mobility two-dimensional electron gas in GaAs quantum wells at millikelvin\ntemperatures. Such high conductivities offer unique opportunities to develop\nlow-dissipation magnon-based spintronic devices.",
        "positive": "Exciton diffusion in a hBN-encapsulated monolayer MoSe2: Excitons, quasi particles composed of an electron and a hole, play an\nimportant role in optical responses in low-dimensional nanostructures. In this\nwork, we have investigated exciton diffusion in a monolayer MoSe2 encapsulated\nbetween flakes of hexagonal boron nitrides (hBN/MoSe2/hBN). Through PL imaging\nand numerical solving the 2D diffusion equation, we revealed that temperature\ndependence of exciton mobility in the hBN/MoSe2/hBN shows non-saturating\nincrease at low temperature, which is qualitatively different from those of\nquantum wells composed of compound semiconductors. Ultraflat structure of\nmonolayer MoSe2 in the hBN/MoSe2/hBN probably leads to the suppression of\ncharged-impurity scattering and surface-roughness scattering."
    },
    {
        "anchor": "Geometrical spin dephasing in quantum dots: We study spin-orbit mediated relaxation and dephasing of electron spins in\nquantum dots. We show that higher order contributions provide a relaxation\nmechanism that dominates for low magnetic fields and is of geometrical origin.\nIn the low-field limit relaxation is dominated by coupling to electron-hole\nexcitations and possibly $1/f$ noise rather than phonons.",
        "positive": "Arrays of Nano-Electromechanical Biosensors Functionalized by\n  Microcontact Printing: The biofunctionalization of nanoelectromechanical structures is critical for\nthe development of new classes of biosensors displaying improved performances\nand higher-level of integration. We propose a modified microcontact printing\nmethod for the functionalization and passivation of large arrays of\nnanocantilevers in a single, self-aligned step. Using fluorescence microscopy\nand resonant frequency measurements, we demonstrate (1) the bioactivity and the\nanti-fouling property of deposited antibodies and BSA molecules and (2) the\npreservation of the nanostructures' mechanical integrity."
    },
    {
        "anchor": "Scanning spin probe based on magnonic vortex quantum cavities: Performing nanoscale scanning electron paramagnetic resonance (EPR) requires\nthree essential ingredients. First, a static magnetic field together to field\ngradients to Zeeman split the electronic energy levels with spatial resolution.\nSecond, a radiofrequency (rf) magnetic field capable of inducing spin\ntransitions. Finally, a sensitive detection method to quantify the energy\nabsorbed by spins. This is usually achieved by combining externally applied\nmagnetic fields with inductive coils or cavities, fluorescent defects or\nscanning probes. Here, we theoretically propose the realization of a EPR\nscanning sensor merging all three characteristics into a single device: the\nvortex core stabilized in ferromagnetic thin-film discs. On one hand, the\nvortex ground state generates a significant static magnetic field and field\ngradients. On the other hand, the precessional motion of the vortex core around\nits equilibrium position produces a circularly polarized oscillating magnetic\nfield, which is enough to produce spin transitions. Finally, the spin-magnon\ncoupling broadens the vortex gyrotropic frequency, suggesting a direct measure\nof the presence of unpaired electrons. Moreover, the vortex core can be\ndisplaced by simply using external magnetic fields of a few mT, enabling EPR\nscanning microscopy with large spatial resolution. Our numerical simulations\nshow that, by using low damping magnets, it is theoretically possible to detect\nsingle spins located on the disc's surface. Vortex nanocavities could also\nattain strong coupling to individual spin molecular qubits, with potential\napplications to mediate qubit-qubit interactions or to implement qubit readout\nprotocols.",
        "positive": "Moire Butterflies: The Hofstadter butterfly spectral patterns of lattice electrons in an\nexternal magnetic field yield some of the most beguiling images in physics.\nHere we explore the magneto-electronic spectra of systems with moire spatial\npatterns, concentrating on the case of twisted bilayer graphene. Because\nlong-period spatial patterns are accurately formed at small twist angles,\nfractal butterfly spectra and associated magneto-transport and\nmagneto-mechanical anomalies emerge at accessible magnetic field strengths."
    },
    {
        "anchor": "Scaling theory for anomalous semiclassical quantum transport: Quantum transport through devices coupled to electron reservoirs can be\ndescribed in terms of the full counting statistics (FCS) of charge transfer.\nTransport observables, such as conductance and shot-noise power are just\ncumulants of FCS and can be obtained from the sample's average density of\ntransmission eigenvalues, which in turn can be obtained from a finite element\nrepresentation of the saddle-point equation of the Keldysh (or supersymmetric)\nnon-linear sigma-model, known as quantum circuit theory. Normal universal\nmetallic behavior in the semiclassical regime is controlled by the presence of\na Fabry-Perot singularity in the average density of transmission eigenvalues.\nWe present general conditions for the suppression of Fabry-Perot modes in the\nsemiclassical regime in a sample of arbitrary shape, a disordered conductor or\na network of ballistic quantum dots, which leads to an anomalous metallic\nphase. Through a double-scaling limit, we derive a scaling equation for\nanomalous metallic transport, in the form of a nonlinear differential equation,\nwhich generalizes the ballistic-diffusive scaling equation of a normal metal.\nThe two-parameter stationary solution of our scaling equation generalizes\nDorokhov's universal single-parameter distribution of transmission eigenvalues.\nWe provide a simple interpretation of the stationary solution using a\nthermodynamic analogy with a spin-glass system. As an application, we consider\na system formed by a diffusive wire coupled via a barrier to\nnormal-superconductor (NS) reservoirs. We observe anomalous reflectionless\ntunneling, when all perfectly transmitting channels are suppressed, which\ncannot be explained by the usual mechanism of disorder-induced opening of\ntunneling channels.",
        "positive": "Effects of parallel electric and magnetic fields on Rydberg excitons in\n  buckled two-dimensional materials: We study direct and indirect magnetoexcitons in Rydberg states in monolayers\nand double-layer heterostructures of Xenes (silicene, germanene, and stanene)\nin external parallel electric and magnetic fields, applied perpendicular to the\nmonolayer and heterostructure. We calculate binding energies of magnetoexcitons\nfor the Rydberg states 1$s$, 2$s$, 3$s$, and 4$s$, by numerical integration of\nthe Schr\\\"{o}dinger equation using the Rytova-Keldysh potential for direct\nmagnetoexciton and both the Rytova-Keldysh and Coulomb potentials for indirect\nexcitons. Latter allows understanding a role of screening in Xenes. In the\nexternal perpendicular electric field, the buckled structure of the Xene\nmonolayers leads to appearance of potential difference between sublattices\nallowing to tune electron and hole masses and, therefore, the binding energies\nand diamagnetic coefficients (DMCs) of magnetoexcitons. We report the energy\ncontribution from electric and magnetic fields to the binding energies and\nDMCs. The tunability of the energy contribution of direct and indirect\nmagnetoexcitons by electric and magnetic fields is demonstrated. It is also\nshown that DMCs of direct excitons can be tuned by the electric field, and the\nDMCs of indirect magnetoexcitons can be tuned by the electric field and\nmanipulated by the number of h-BN layers. Therefore, these allowing the\npossibility of electronic devices design that can be controlled by external\nelectric and magnetic fields and the number of h-BN layers. The calculations of\nthe binding energies and DMCs of magnetoexcitons in Xenes monolayers and\nheterostructures are novel and can be compared with the experimental results\nwhen they will be available."
    },
    {
        "anchor": "Thermal disorder driven magnetic phases in van der Waals magnet CrI3: Magnetic phase transitions often occur spontaneously at specific critical\ntemperatures. The presence of more than one critical temperature (Tc) has been\nobserved in several compounds where the coexistence of competing magnetic\norders highlights the importance of phase separation driven by different\nfactors such as pressure, temperature and chemical composition. However, it is\nunknown whether recently discovered two-dimensional (2D) van der Walls (vdW)\nmagnetic materials show such intriguing phenomena that can result in rich phase\ndiagrams with novel magnetic features to be explored. Here we show the\nexistence of three magnetic phase transitions at different Tc's in 2D vdW\nmagnet CrI3 revealed by a complementary suite of muon spin relaxation-rotation,\nsuperconducting quantum interference device magnetometry, and large-scale\natomistic simulations including higher-order exchange interactions. We find\nthat the traditionally identified Curie temperature of bulk CrI3 at 61 K does\nnot correspond to the long-range order in the full volume (VM) of the crystal\nbut rather a partial transition with less than 25% of VM being magnetically\nspin-ordered. This transition is composed of highly disordered domains with the\neasy-axis component of the magnetization Sz not being fully spin-polarized but\ndisordered by in-plane components (Sx, Sy) over the entire layer. As the system\ncools down, two additional phase transitions at 50 K and 25 K drive the system\nto 80% and nearly 100% of the magnetically ordered volume, respectively, where\nthe ferromagnetic ground state has a marked Sz character yet also displaying\nfinite contributions of Sx and Sy to the total magnetization. Our results\nindicate that volume-wise competing electronic phases play an important role in\nthe magnetic properties of CrI3 which set a much lower threshold temperature\nfor exploitation in magnetic device-platforms than initially considered.",
        "positive": "Scaling of the quantum-Hall plateau-plateau transition in graphene: The temperature dependence of the magneto-conductivity in graphene shows that\nthe widths of the longitudinal conductivity peaks, for the N=1 Landau level of\nelectrons and holes, display a power-law behavior following $\\Delta \\nu \\propto\nT^{\\kappa}$ with a scaling exponent $\\kappa = 0.37\\pm0.05$. Similarly the\nmaximum derivative of the quantum Hall plateau transitions\n$(d\\sigma_{xy}/d\\nu)^{max}$ scales as $T^{-\\kappa}$ with a scaling exponent\n$\\kappa = 0.41\\pm0.04$ for both the first and second electron and hole Landau\nlevel. These results confirm the universality of a critical scaling exponent.\nIn the zeroth Landau level, however, the width and derivative are essentially\ntemperature independent, which we explain by a temperature independent\nintrinsic length that obscures the expected universal scaling behavior of the\nzeroth Landau level."
    },
    {
        "anchor": "Electron Confinement Induced by Diluted Hydrogen-like Ad-atoms in\n  Graphene Ribbons: We report the electronic properties of two-dimensional systems made of\ngraphene nanoribbons which are patterned with ad-atoms in two separated\nregions. Due to the extra electronic confinement induced by the presence of the\nimpurities, we find resonant levels, quasi-bound and impurity-induced localized\nstates, which determine the transport properties of the system. Regardless of\nthe ad-atom distribution in the system, we apply band-folding procedures to\nsimple models and predict the energies and the spatial distribution of those\nimpurity-induced states. We take into account two different scenarios: gapped\ngraphene and the presence of randomly distributed ad-atoms in a low dilution\nregime. In both cases the defect-induced resonances are still detected. Our\nfindings would encourage experimentalist to synthesize these systems and\ncharacterize their quasi-localized states employing, for instance, scanning\ntunneling spectroscopy (STS). Additionally, the resonant transport features\ncould be used in electronic applications and molecular sensor devices.",
        "positive": "Modulation of bilayer quantum Hall states by tilted-field-induced\n  subband-Landau-level coupling: We study effects of tilted magnetic fields on energy levels in a\ndouble-quantum-well (DQW) system, focusing on the coupling of subbands and\nLandau levels (LLs). The subband-LL coupling induces anticrossings between LLs,\nmanifested directly in the magnetoresistance. The anticrossing gap becomes\nlarger than the spin splitting at the tilting angle $\\theta \\sim 20^\\circ $ and\nlarger than the cyclotron energy at $\\theta \\sim 50^\\circ $, demonstrating that\nthe subband-LL coupling exerts a strong influence on quantum Hall states even\nin at a relatively small $\\theta $ and plays a dominant role for larger $\\theta\n$. We also find that when the DQW potential is asymmetric, LL coupling occurs\neven within a subband. Calculations including higher-order coupling reproduce\nthe experimental results quantitatively well."
    },
    {
        "anchor": "Strain-tunable Single Photon Sources in WSe2 Monolayers: The appearance of single photon sources in atomically thin semiconductors\nholds great promises for the development of a flexible and ultra-compact\nquantum technology, in which elastic strain engineering can be used to tailor\ntheir emission properties. Here, we show a compact and hybrid\n2D-semiconductor-piezoelectric device that allows for controlling the energy of\nsingle photons emitted by quantum emitters localized in wrinkled WSe2\nmonolayers. We demonstrate that strain fields exerted by the piezoelectric\ndevice can be used to tune the energy of localized excitons in WSe2 up to 18\nmeV in a reversible manner, while leaving the single photon purity unaffected\nover a wide range. Interestingly, we find that the magnitude and in particular\nthe sign of the energy shift as a function of stress is emitter dependent. With\nthe help of finite element simulations we suggest a simple model that explains\nour experimental observations and, furthermore, discloses that the type of\nstrain (tensile or compressive) experienced by the quantum emitters strongly\ndepends on their localization across the wrinkles. Our findings are of strong\nrelevance for the practical implementation of single photon devices based on\ntwo-dimensional materials as well as for understanding the effects of strain on\ntheir emission properties.",
        "positive": "Excitonic complexes in MOCVD-grown InGaAs/GaAs quantum dots emitting at\n  telecom wavelengths: Hereby, we present a comprehensive experimental and theoretical study of the\nelectronic structure and optical properties of excitonic complexes in\nstrain-engineered InGaAs/GaAs quantum dots (QDs) grown by metal-organic\nchemical vapour deposition and emitting at the 1300 nm telecommunication\nwindow. Single QD properties have been determined experimentally for a number\nof nanostructures by means of excitation-power-dependent and\npolarization-resolved microphotoluminescence and further compared with the\nresults of confined states calculations employing the 8-band kp theory combined\nwith the configuration interaction method. The origin of excitonic complexes\nhas been exemplarily confirmed based on magnetooptical and correlation\nspectroscopy study. Understanding the influence of structural parameters and\ncompositions (of QDs themselves as well as in the neighbouring strain reducing\nlayer) allows to distinguish which of them are crucial to control the emission\nwavelength to achieve the telecommunication spectral range or to affect binding\nenergies of the fundamental excitonic complexes. The obtained results provide\ndeeper knowledge on control and on limitations of the investigated structures\nin terms of good spectral isolation of individual optical transitions and the\nspatial confinement that are crucial in view of QD applications in\nsingle-photon sources of high purity at telecom wavelengths."
    },
    {
        "anchor": "Spin Inelastic Electron Tunneling Spectroscopy on Local Spin Adsorbed on\n  Surface: The recent experimental conductance measurements taken on magnetic impurities\non metallic surfaces, using scanning tunneling microscopy technique and\nsuggesting occurrence of inelastic scattering processes, are theoretically\naddressed. We argue that the observed conductance signatures are caused by\ntransitions between the spin states which have opened due to e.g. exchange\ncoupling between the local spins and the tunneling electrons, and are directly\ninterpretable in terms of inelastic transitions energies. Feasible measurements\nusing spin-polarized scanning tunneling microscopy that would enable new\ninformation about the excitation spectrum of the local spins are discussed.",
        "positive": "Hall Conductivity for Two Dimensional Magnetic Systems: A Kubo inspired formalism is proposed to compute the longitudinal and\ntransverse dynamical conductivities of an electron in a plane (or a gas of\nelectrons at zero temperature) coupled to the potential vector of an external\nlocal magnetic field, with the additional coupling of the spin degree of\nfreedom of the electron to the local magnetic field (Pauli Hamiltonian). As an\nexample, the homogeneous magnetic field Hall conductivity is rederived. The\ncase of the vortex at the origin is worked out in detail. This system happens\nto display a transverse Hall conductivity ($P$ breaking effect) which is\nsubleading in volume compared to the homogeneous field case, but diverging at\nsmall frequency like $1/\\omega^2$. A perturbative analysis is proposed for the\nconductivity in the random magnetic impurity problem (Poissonian vortices in\nthe plane). At first order in perturbation theory, the Hall conductivity\ndisplays oscillations close to the classical straight line conductivity of the\nmean magnetic field."
    },
    {
        "anchor": "Spin selective coupling to Majorana zero modes in mixed singlet and\n  triplet superconducting nanowire: We theoretically investigate the transport properties of a quasi one\ndimensional ferromagnet-superconductor junction where the superconductor\nconsists of mixed singlet and triplet pairings. We show that\n  the relative orientation of the stoner field ($\\bf{\\tilde{h}}$) in the\nferromagnetic lead and the $\\bf{d}$ vector of the superconductor acts like a\non-off switch for the zero bias conductance of the device.\n  In the regime, where triplet pairing amplitude dominates over the singlet\ncounterpart (topological phase), a pair of Majorana zero modes appear at each\nend of the superconducting part of the nanowire. When $\\bf{\\tilde{h}}$ is\nparallel or anti-parallel to the $\\bf{d}$ vector, transport gets completely\nblocked due to blockage in pairing while, when $\\bf{\\tilde{h}}$ and $\\bf{d}$\nare perpendicular to each other, the zero energy two terminal differential\nconductance spectra exhibits sharp transition from $4e^2/h$ to $2e^2/h$ as the\nmagnetization strength in the lead becomes larger than the chemical potential\nindicating the spin selective coupling of pair of Majorana zero modes to the\nlead.",
        "positive": "Effects of optical and surface polar phonons on the optical conductivity\n  of doped graphene: Using the Kubo linear response formalism, we study the effects of intrinsic\ngraphene optical and surface polar phonons (SPPs) on the optical conductivity\nof doped graphene. We find that inelastic electron-phonon scattering\ncontributes significantly to the phonon-assisted absorption in the optical gap.\nAt room temperature, this midgap absorption can be as large as 20-25% of the\nuniversal ac conductivity for graphene on polar substrates due to strong\nelectron-SPP coupling. The midgap absorption, moreover, strongly depends on the\nsubstrates and doping levels used. With increasing temperature, the midgap\nabsorption increases, while the Drude peak, on the other hand, becomes broader\nas inelastic electron-phonon scattering becomes more probable. Consequently,\nthe Drude weight decreases with increasing temperature."
    },
    {
        "anchor": "Unexpected results for the non-trivial fusion of Majorana zero modes in\n  interacting quantum-dot arrays: Motivated by recent experimental reports of Majorana zero modes (MZMs) in\nquantum-dot systems at the ``sweet spot'', where the electronic hopping $t_h$\nis equal to the superconducting coupling $\\Delta$, we study the time-dependent\nspectroscopy corresponding to the {\\it non-trivial} fusion of MZMs. The\nexpression non-trivial refers to the fusion of Majoranas from different\noriginal pairs of MZMs, each with well-defined parities. For the first time, we\nemploy an experimentally accessible time-dependent real-space local\ndensity-of-states (LDOS) method to investigate the non-trivial MZMs fusion\noutcomes in canonical chains and in a Y-shape array of interacting electrons.\nIn the case of quantum-dot chains where two pairs of MZMs are initially\ndisconnected, after fusion we find equal-height peaks in the electron and hole\ncomponents of the LDOS, signaling non-trivial fusion into both the vacuum $I$\nand fermion $\\Psi$ channels with equal weight. For $\\pi$-junction quantum-dot\nchains, where the superconducting phase has opposite signs on the left and\nright portions of the chain, after the non-trivial fusion, surprisingly we\nobserved the formation of an exotic two-site MZM near the center of the chain,\ncoexisting with another single-site MZM. Furthermore, we also studied the\nfusion of three MZMs in the Y-shape geometry. In this case, after the fusion we\nobserved the novel formation of another exotic multi-site MZM, with properties\ndepending on the connection and geometry of the central region of the Y-shape\nquantum-dot array.",
        "positive": "Disorder-induced enhancement of transport through graphene p-n junctions: We investigate the electron transport through a graphene p-n junction under a\nperpendicular magnetic field. By using Landauar-Buttiker formalism combining\nwith the non-equilibrium Green function method, the conductance is studied for\nthe clean and disordered samples. For the clean p-n junction, the conductance\nis quite small. In the presence of disorders, it is strongly enhanced and\nexhibits plateau structure at suitable range of disorders. Our numerical\nresults show that the lowest plateau can survive for a very broad range of\ndisorder strength, but the existence of high plateaus depends on system\nparameters and sometimes can not be formed at all. When the disorder is\nslightly outside of this disorder range, some conductance plateaus can still\nemerge with its value lower than the ideal value. These results are in\nexcellent agreement with the recent experiment."
    },
    {
        "anchor": "Long-lifetime Polariton BEC in a Microcavity with an Embedded Quantum\n  Well and Graphene: We study the propagation of a Bose-Einstein condensate (BEC) of long-lifetime\nexciton polaritons in a high-quality microcavity with an embedded semiconductor\nquantum well or a graphene layer using the Gross-Pitaevskii equation. It is\nshown that in these heterostructures the BEC of the long-lifetime polaritons\ncan propagate over the distance up to 0.5 mm. The obtained results are\nconsistent with the recent experimental observations for GaAs/AlGaAs\nmicrocavity. It is demonstrated that the BEC density in a polariton trace in a\nmicrocavity with embedded graphene at large distances from the excitation spot\nis higher for the microcavity with higher dielectric constant. It is also\npredicted that the propagation of a polariton BEC in a microcavity with\ngraphene is dynamically tunable by changing the gap energy, that makes it\npotentially useful for applications in integrated optical circuits.",
        "positive": "Energy exchange and localization of low-frequency oscillations in\n  single-walled carbon nanotubes: We present the results of analytical study and Molecular Dynamics simulation\nof low energy nonlinear non-stationary dynamics of single-walled carbon\nnanotubes (CNTs). New phenomena of intensive energy exchange between different\nparts of CNT and weak energy localization in a part CNT are analytically\npredicted in the framework of the continuum shell theory. These phenomena take\nplace for CNTs of finite length with medium aspect ratio under different\nboundary conditions. Their origin is clarified by means of the concept of\nLimiting Phase Trajectory, and the analytical results are confirmed by the MD\nsimulation of simply supported CNTs."
    },
    {
        "anchor": "Spin Texture in Quantum Point Contacts in the Presence of Lateral Spin\n  Orbit Coupling: A non-equilibrium Green's function formalism is used to study in detail the\nballistic conductance of asymmetrically biased side-gated quantum point\ncontacts (QPCs) in the presence of lateral spin-orbit coupling and\nelectron-electron interaction for a wide range of QPC dimensions and gate bias\nvoltage. Various conductance anomalies are predicted below the first quantized\nconductance plateau (G0=2e2/h) which occur due to spontaneous spin polarization\nin the narrowest portion of the QPC. The number of observed conductance\nanomalies increases with increasing aspect ratio (length/width) of the QPC\nconstriction. These anomalies are fingerprints of spin textures in the narrow\nportion of the QPC.",
        "positive": "Quasiparticle Poisoning and Quantum Coherence in a Differential Charge\n  Qubit: We demonstrate the operation of a differential single Cooper-pair box, a\ncharge qubit consisting of two aluminum islands, isolated from ground, coupled\nby a pair of small-area Josephson junctions, and read out with a\nsuperconducting differential radio-frequency single electron transistor. We\nhave tested four devices, all of which show evidence of quasiparticle\npoisoning. The devices are characterized with microwave spectroscopy and\ntemperature dependence studies, and Coulomb staircases are shown to be\ne-periodic in all samples. However, coherent control is still possible with\nnon-adiabatic voltage pulses. Coherent oscillation experiments and a relaxation\ntime measurement were performed using a charge derivative readout technique."
    },
    {
        "anchor": "Quantum Oscillations of Tunnel Magnetoresistance Induced by Spin-Wave\n  Excitations in Ferromagnet-Ferromagnet-Ferromagnet Double Barrier Tunnel\n  Junctions: The possibility of quantum oscillations of the tunnel conductance and\nmagnetoresistance induced by spin-wave excitations in a\nferromagnet-ferromagnet-ferromagnet double barrier tunnel junction, when the\nmagnetizations of the two side ferromagnets are aligned antiparallel to that of\nthe middle ferromagnet, is investigated in a self-consistent manner by means of\nKeldysh nonequilibrium Green function method. It has been found that owing to\nthe s-d exchange interactions between conduction electrons and the spin density\ninduced by spin accumulation in the middle ferromagnet, the differential\nconductance and the TMR indeed oscillate with the increase of bias voltage,\nbeing consistent with the phenomenon that is observed recently in experiments.\nThe effects of magnon modes, the energy levels of electrons as well as the\nmolecular field in the central ferromagnet on the oscillatory transport\nproperty of the system are also discussed.",
        "positive": "Field-Induced SDW and Butterfly Spectrum in Three Dimensions: Landau's quantization for incompletely nested Fermi surfaces is known to give\nrise to magnetic-field-induced spin-density waves(FISDW) in two-dimensional\norganic metals. Here we show that three-dimensional(3D) systems can have\n3D-specific series of FISDW phases as energetically stable states, for which we\nclarify how and why they appear as the magnetic field is tilted. Each phase is\ncharacterized by quantized Hall effect for each of $\\sigma_{xy}$ and\n$\\sigma_{zx}$ that reside on a fractal spectrum like Hofstadter's butterfly."
    },
    {
        "anchor": "Detecting phonon blockade with photons: Measuring the quantum dynamics of a mechanical system, when few phonons are\ninvolved, remains a challenge. We show that a superconducting microwave\nresonator linearly coupled to the mechanical mode constitutes a very powerful\nprobe for this scope. This new coupling can be much stronger than the usual\nradiation pressure interaction by adjusting a gate voltage. We focus on the\ndetection of phonon blockade, showing that it can be observed by measuring the\nstatistics of the light in the cavity. The underlying reason is the formation\nof an entangled state between the two resonators. Our scheme realizes a\nphonotonic Josephson junction, giving rise to coherent oscillations between\nphonons and photons as well as a self-trapping regime for a coupling smaller\nthan a critical value. The transition from the self-trapping to the oscillating\nregime is also induced dynamically by dissipation.",
        "positive": "Nonlinear Optical Probe of Indirect Excitons: We propose the application of nonlinear optics for studies of spatially\nindirect excitons in coupled quantum wells. We demonstrate, that despite their\nvanishing oscillator strength, indirect excitons can strongly contribute to the\nphotoinduced reflectivity and Kerr rotation. This phenomenon is governed by the\ninteraction between direct and indirect excitons. Both dark and bright states\nof indirect excitons can be probed by these nonlinear optical techniques."
    },
    {
        "anchor": "Berry phases for composite fermions: effective magnetic field and\n  fractional statistics: The quantum Hall superfluid is presently the only viable candidate for a\nrealization of quasiparticles with fractional Berry phase statistics. For a\nsimple vortex excitation, relevant for a subset of fractional Hall states\nconsidered by Laughlin, non-trivial Berry phase statistics were demonstrated\nmany years ago by Arovas, Schrieffer, and Wilczek. The quasiparticles are in\ngeneral more complicated, described accurately in terms of excited composite\nfermions. We use the method developed by Kjonsberg, Myrheim and Leinaas to\ncompute the Berry phase for a single composite-fermion quasiparticle, and find\nthat it agrees with the effective magnetic field concept for composite\nfermions. We then evaluate the \"fractional statistics\", related to the change\nin the Berry phase for a closed loop caused by the insertion of another\ncomposite-fermion quasiparticle in the interior. Our results support the\ngeneral validity of fractional statistics in the quantum Hall superfluid, while\nalso giving a quantitative account of corrections to it when the quasiparticle\nwave functions overlap. Many caveats, both practical and conceptual, are\nmentioned that will be relevant to an experimental measurement of the\nfractional statistics. A short report on some parts of this article has\nappeared previously.",
        "positive": "Interaction-induced Renormalization of Andreev Reflection: We analyze the charge transport between a one-dimensional weakly interacting\nelectron gas and a superconductor within the scaling approach in the basis of\nscattering states. We derive the renormalization group equations, which fully\naccount for the intrinsic energy dependence due to Andreev reflection. A strong\nrenormalization of the corresponding reflection phase is predicted even for a\nperfectly transparent metal-superconductor interface. The interaction-induced\nsuppression of the Andreev conductance is shown to be highly sensitive to the\nnormal state resistance, providing a possible explanation of experiments with\ncarbon-nanotube/superconductor junctions by Morpurgo et al. [Science 286, 263\n(2001)]."
    },
    {
        "anchor": "The Density of Surface States in Weyl Semimetals: Weyl semimetal is a three-dimensional material with a conical spectrum near\nan even number of point nodes, where two bands touch each other. Here we study\nspectral properties of surface electron states in such a system. We show that\nthe density of surface states possesses a logarithmic singularity for the\nenergy $\\varepsilon \\to 0$. It decreases linearly at the intermediate energy of\nsurface electron states and approaches zero as $\\sqrt{1-\\varepsilon}$ for\n$\\varepsilon \\to 1$. This universal behavior is a hallmark of the topological\norder that offers a new wide range of applications.",
        "positive": "Control of valley optical conductivity and topological phases in buckled\n  hexagonal lattice by orientation of in-plane magnetic field: We investigate the optical conductivity, along with longitudinal and\ntransverse conductivities, in buckled hexagonal lattice such as silicene\nsubjected to both an in-plane magnetic field and a perpendicular electric\nfield. In this model, we neglect the effect of the spin-orbit interaction,\nwhich is of a smaller order compared to the strong staggered potential and the\nnext-nearest hoping energy. The orientations of the in-plane magnetic field and\nthe perpendicular electric field give rise to a non-uniform, tunable gap. The\nChern number for each valley degree of freedom deviates from being constant but\nremains steady when summed over the entire Brillouin zone. The longitudinal and\ntransverse currents, in the case of a specific valley, can be selected by\nadjusting the direction of the electric field in the semimetal phase.\nFurthermore, the defining characteristics of topological phases induces the\nrapid change in longitudinal conductivity when varying the angle of orientation\nof the in-plane magnetic field under monochromatic light, and perfect valley\nfiltering in transverse conductivity. The transverse current associated with a\nspecific valley can be selected when the angle of orientation satisfies the\nspecific conditions. This investigation paves the way for materials design with\nvalley-locked current, using a specific orientation of the in-plane magnetic\nfield."
    },
    {
        "anchor": "Subwavelength and directional control of flexural waves in zone-folding\n  induced topological plates: Inspired by the quantum spin Hall effect shown by topological insulators, we\npropose a plate structure that can be used to demonstrate the pseudo-spin Hall\neffect for flexural waves. The system consists of a thin plate with\nperiodically arranged resonators mounted on its top surface. We extend a\ntechnique based on the plane wave expansion method to identify a double Dirac\ncone emerging due to the zone-folding in frequency band structures. This\nparticular design allows us to move the double Dirac cone to a lower frequency\nthan the resonating frequency of local resonators. We then manipulate the\npattern of local resonators to open subwavelength Bragg band gaps that are\ntopologically distinct. Building on this method, we verify numerically that a\nwaveguide at an interface between two topologically distinct resonating plate\nstructures can be used for guiding low-frequency, spin-dependent one-way\nflexural waves along a desired path with bends.",
        "positive": "Magnetic Response in Mesoscopic Hubbard Rings: A Mean Field Study: The present work proposes an idea to remove the long standing controversy\nbetween the calculated and measured current amplitudes carried by a small\nconducting ring upon the application of an Aharonov-Bohm (AB) flux $\\phi$.\nWithin a mean field Hartree-Fock (HF) approximation we numerically calculate\npersistent current, Drude weight, low-field magnetic susceptibility and related\nissues. Our analysis may be inspiring for studying magnetic response in\nnano-scale loop geometries."
    },
    {
        "anchor": "Pseudo-magnetic field distribution and pseudo-Landau levels in suspended\n  graphene flakes: Combining the tight-binding approximation and linear elasticity theory for a\nplanar membrane, we investigate stretching of a graphene flake assuming that\ntwo opposite edges of the sample are clamped by the contacts. We show that,\ndepending on the aspect ratio of the flake and its orientation, gapped states\nmay form in the membrane in the vicinity of the contacts. This gap in the\npre-contact region should be biggest for the armchair orientation of the flake\nand width to length ratio of around 1.",
        "positive": "Temperature induced modulation of resonant Raman scattering in bilayer\n  2H-MoS$_{2}$: The temperature evolution of the resonant Raman scattering from high-quality\nbilayer 2H-MoS$_{2}$ encapsulated in hexagonal BN flakes is presented. The\nobserved resonant Raman scattering spectrum as initiated by the laser energy of\n1.96 eV, close to the A excitonic resonance, shows rich and distinct\nvibrational features that are otherwise not observed in non-resonant\nscattering. The appearance of 1$^{st}$ and 2$^{nd}$ order phonon modes is\nunambiguously observed in a broad range of temperatures from 5 K to 320 K. The\nspectrum includes the Raman-active modes, $i.e.$ E$_\\textrm{1g}^{2}$($\\Gamma$)\nand A$_\\textrm{1g}$($\\Gamma$) along with their Davydov-split counterparts,\n$i.e.$ E$_\\textrm{1u}$($\\Gamma$) and B$_\\textrm{1u}$($\\Gamma$). The temperature\nevolution of the Raman scattering spectrum brings forward key observations, as\nthe integrated intensity profiles of different phonon modes show diverse\ntrends. The Raman-active A$_{1g}$($\\Gamma$) mode, which dominates the Raman\nscattering spectrum at $T$=5~K quenches with increasing temperature.\nSurprisingly, at room temperature the B$_\\textrm{1u}$($\\Gamma$) mode, which is\ninfrared-active in the bilayer, is substantially stronger than its nominally\nRaman-active A$_\\textrm{1g}$($\\Gamma$) counterpart."
    },
    {
        "anchor": "Coupling between quantum Hall state and electromechanics in suspended\n  graphene resonator: Using graphene resonator, we perform electromechanical measurements in\nquantum Hall regime to probe the coupling between a quantum Hall (QH) system\nand its mechanical motion. Mechanically perturbing the QH state through\nresonance modifies the DC resistance of the system and results in a\nFano-lineshape due to electronic interference. Magnetization of the system\nmodifies the resonator's equilibrium position and effective stiffness leading\nto changes in resonant frequency. Our experiments show that there is an\nintimate coupling between the quantum Hall state and mechanics - electron\ntransport is affected by physical motion and in turn the magnetization modifies\nthe electromechanical response.",
        "positive": "Aharonov-Bohm oscillations of four-probe resistance in topological\n  quantum rings in silicene and bilayer graphene: We consider observation of Aharonov-Bohm oscillations in clean systems based\non the flow of topologically protected currents in silicene and bilayer\ngraphene. The chiral channels in these materials are defined by the flips of\nthe vertical electric field. The line of the flip confines chiral currents\nflowing along it in the direction determined by the valley. We present an\nelectric field profile that forms a crossed ring to which four terminals can be\nattached, and find that the conductance matrix elements oscillate in the\nperpendicular magnetic field in spite of the absence of backscattering. We\npropose a four-probe resistance measurement setup, and demonstrate that the\nresistance oscillations have large visibility provided that the system is\nprepared in such a way that a direct transfer of the chiral carriers between\nthe current probes is forbidden."
    },
    {
        "anchor": "Non-monotonic heat dissipation phenomenon in close-packed quasi-2D and\n  3D hotspot system: Transient heat dissipation in close-packed quasi-2D nanoline and 3D\nnanocuboid hotspot systems is studied based on phonon Boltzmann transport\nequation. It is found that, counter-intuitively, the heat dissipation\nefficiency is not a monotonic function of the distance between adjacent\nnanoscale heat sources: the heat dissipation efficiency reaches the highest\nvalue when this distance is comparable to the phonon mean free path. This is\ndue to the competition of two thermal transport processes: quasiballistic\ntransport when phonons escape from the nanoscale heat source and the scattering\namong phonons originating from adjacent nanoscale heat source.",
        "positive": "Torsional Anomalies and Bulk-Dislocation Correspondence in Weyl Systems: Based on the supersymmetric quantum mechanical approach, we have\nsystematically studied both the $U\\left(1\\right)$ gauge anomaly and the\ndiffeomorphism anomaly in Weyl systems with torsion, curvature and external\nelectromagnetic fields. These anomalies relate to the chiral current (or\ncurrent) non-conservation and chiral energy-momentum (or energy-momentum)\nnon-conservation, respectively, which can be applied to the $^{3}\\text{He-A}$\nphase, the chiral superconductors and the Weyl semimetals with dislocations and\ndisclinations. In sharp difference with other anomalies, there exist torsional\nanomalies depending on the position of Weyl nodes in the energy-momentum space.\nThese anomalies originate from particles pumped up through the Weyl nodes and\nthey are thus insensitive to the ultra-violet physics, while the Nieh-Yan\nanomaly is from the particle inflow through the ultra-violet cut-off. The\ncurrent non-conservation as well as the energy-momentum non-conservation are\nfound, which stem from the zero modes trapped in the dislocations and they can\nbe understood from the Callan-Harvey mechanism. Finally, by comparing our\nresults with the well-established momentum anomaly in the $^{3}\\text{He-A}$\nphase, the Nieh-Yan term as well as other cut-off dependent terms are shown to\nbe negligible, because the ratio between the Lorentz symmetry breaking scale\nand the chemical potential is of order $10^{-5}$."
    },
    {
        "anchor": "Spin-orbit coupling and spin relaxation in phosphorene: Intrinsic versus\n  extrinsic effects: First-principles calculations of the essential spin-orbit and spin relaxation\nproperties of phosphorene are performed. Intrinsic spin-orbit coupling induces\nspin mixing with the probability of $b^2 \\approx 10^{-4}$, exhibiting a large\nanisotropy, following the anisotropic crystalline structure of phosphorene. For\nrealistic values of the momentum relaxation times, the intrinsic\n(Elliott--Yafet) spin relaxation times are hundreds of picoseconds to\nnanoseconds. Applying a transverse electric field (simulating gating and\nsubstrates) generates extrinsic $C_{2v}$ symmetric spin-orbit fields in\nphosphorene, which activate the D'yakonov--Perel' mechanism for spin\nrelaxation. It is shown that this extrinsic spin relaxation also has a strong\nanisotropy, and can dominate over the Elliott-Yafet one for strong enough\nelectric fields. Phosphorene on substrates can thus exhibit an interesting\ninterplay of both spin relaxation mechanisms, whose individual roles could be\ndeciphered using our results.",
        "positive": "Large-scale mapping of moir\u00e9 superlattices by Raman imaging of\n  interlayer breathing mode and moir\u00e9 phonons: Moir\\'e superlattices can induce correlated-electronic phases in twisted\nvan-der-Waals materials. Strongly correlated quantum phenomena emerge, such as\nsuperconductivity and the Mott-insulating state. However, moir\\'e superlattices\nproduced through artificial stacking can be quite inhomogeneous, which hampers\nthe development of a clear correlation between the moir\\'e period and the\nemerging electrical and optical properties. Here we demonstrate in\ntwisted-bilayer transition-metal dichalcogenides that low-frequency Raman\nscattering can be utilized not only to detect atomic reconstruction, but also\nto map out the inhomogeneity of the moir\\'e lattice over large areas. The\nmethod is established based on the finding that both the interlayer-breathing\nmode and moir\\'e phonons are highly susceptible to the moir\\'e period and\nprovide characteristic fingerprints. We visualize microscopic domains with an\neffective twist-angle resolution of ~0.1{\\deg}. This ambient non-invasive\nmethodology can be conveniently implemented to characterize and preselect\nhigh-quality areas of samples for subsequent device fabrication, and for\ntransport and optical experiments."
    },
    {
        "anchor": "Observation of edge magnetoplasmon squeezing in a quantum Hall conductor: Squeezing of the quadratures of the electromagnetic field has been\nextensively studied in optics and microwaves. However, previous works focused\non the generation of squeezed states in a low impedance ($Z_0 \\approx 50\n\\Omega$) environment. We report here on the demonstration of the squeezing of\nbosonic edge magnetoplasmon modes in a quantum Hall conductor whose\ncharacteristic impedance is set by the quantum of resistance ($R_K \\approx 25 k\n\\Omega$), offering the possibility of an enhanced coupling to low-dimensional\nquantum conductors. By applying a combination of dc and ac drives to a quantum\npoint contact, we demonstrate squeezing and observe a noise reduction 18\\%\nbelow the vacuum fluctuations. This level of squeezing can be improved by using\nmore complex conductors, such as ac driven quantum dots or mesoscopic\ncapacitors.",
        "positive": "Occurrence control of charged exciton for a single CdSe quantum dot at\n  cryogenic temperatures on an optical nanofiber: We discuss photo-luminescence characteristics of CdSe core/shell quantum dots\nat cryogenic temperatures using a hybrid system of a single quantum dot and an\noptical nanofiber. The key point is to control the emission species of quantum\ndot to charged excitons, known as trions, which have superior characteristics\nto neutral excitons. We investigate the photocharging behavior for the quantum\ndots by varying the wavelength and intensity of irradiating laser light, and\nestablish a method to create a permanently charged situation which lasts as\nlong as the cryogenic temperature is maintained. The present photocharging\nmethod may open a new route to applying the CdSe quantum dots in quantum\nphotonics, and the hybrid system of photocharged quantum-dot and optical\nnanofiber may readily be applicable to a fiber-in-line single-photon generator."
    },
    {
        "anchor": "Tutorial: Computing topological invariants in two-dimensional photonic\n  crystals: The field of topological photonics emerged as one of the most promising areas\nfor applications in transformative technologies: possible applications are in\ntopological lasers or quantum optics interfaces. Nevertheless, efficient and\nsimple methods for diagnosing the topology of optical systems remain elusive\nfor an important part of the community. In this tutorial, we provide a summary\nof numerical methods to calculate topological invariants emerging from the\npropagation of light in photonic crystals. We first describe the fundamental\nproperties of wave propagation in lattices with a space-dependent periodic\nelectric permittivity. Next, we provide an introduction to topological\ninvariants; proposing an optimal strategy to calculate them through the\nnumerical evaluation of Maxwell's equation in a discretized reciprocal space.\nFinally, we will complement the tutorial with a few practical examples of\nphotonic crystal systems showing different topological properties, such as\nphotonic valley-Chern insulators, photonic crystals presenting an \"obstructed\natomic limit\", photonic systems supporting fragile topology and finally\nphotonic Chern insulators, where we also periodically modulated the magnetic\npermeability.",
        "positive": "Improvement of the 3$\u03c9$ thermal conductivity measurement technique\n  at nanoscale: The reduction of the thermal conductivity in nanostructures opens up the\npossibility of exploiting for thermoelectric purposes also materials such as\nsilicon, which are cheap, available and sustainable but with a high thermal\nconductivity in their bulk form. The development of thermoelectric devices\nbased on these innovative materials requires reliable techniques for the\nmeasurement of thermal conductivity on a nanometric scale. The approximations\nintroduced by conventional techniques for thermal conductivity measurements can\nlead to unreliable results when applied to nanostructures, because heaters and\ntemperature sensors needed for the measurement cannot have a negligible size,\nand therefore perturb the result. In this paper we focus on the 3$\\omega$\ntechnique, applied to the thermal conductivity measurement of suspended silicon\nnanomembranes. To overcome the approximations introduced by conventional\nanalytical models used for the interpretation of the 3$\\omega$ data, we propose\nto use a numerical solution, performed by means of finite element modeling, of\nthe thermal and electrical transport equations. An excellent fit of the\nexperimental data will be presented, discussed, and compared with an analytical\nmodel."
    },
    {
        "anchor": "Instability of Walker Propagating Domain Wall in Magnetic Nanowires: Stability of the well-known Walker propagating domain wall (DW) solution of\nthe Landau-Lifshitz-Gilbert equation is analytically investigated.\nSurprisingly, the Walker's rigid body propagating DW mode is not stable against\nthe spin wave/wavepacket emission. In the low field region only stern spin\nwaves are emitted while both stern and bow waves are generated under high\nfields. In a high enough field, but below the Walker breakdown field, the\nWalker solution could be convective/absolute unstable if the transverse\nmagnetic anisotropy is larger than a critical value, corresponding to a\nsignificant modification of the DW profile and DW propagating speed.",
        "positive": "The Canonical Flux Quantization and IQHE(revised): It is shown that the canonical flux quantization, which is described by the\nuncertainty relation on the phase space of the flux system, can result in the\nquantization of Hall-measures. Further it is shown that the polarization of\nthis phase space, which is necessary for its quantization, results in the\nvanishing of longitudinal resistivity and conductivity. The equivalence between\nthis approach and the topological approach to QHE is also discussed."
    },
    {
        "anchor": "Level dynamics and avoided level crossings in driven disordered quantum\n  dots: The statistical properties of the dynamics of energy levels are investigated\nin the case of two two-dimensional disordered quantum dot models with nearest\nneighbor hopping subjected to external time-dependent perturbations. While in\nthe first model the external drivings are realized by a continuous variation of\nthe on-site energies, in the second one it is generated by deformations of a\nparabolic potential. We concentrate on the effects of the potential on the\nlocalization properties and investigate the statistics of the energy level\nvelocities and curvatures regarding their typical magnitudes and domain of\nagreement with the predictions of Random Matrix Theory (RMT) for the Gaussian\nOrthogonal, Unitary and Symplectic ensembles. Moreover, the statistical\nproperties of the avoided level crossings are investigated in terms of the\ncorresponding Landau-Zener parameters. We find that the strength of the\nLandau-Zener transitions exhibits universal behavior which also implies\nuniversal single-particle dynamics for slow perturbations independent of the\ndisorder and potential strength, the system size and the symmetry class. These\nresults can be verified experimentally by measurements of single-particle\nenergy spectra in quantum dots.",
        "positive": "A comparative study of fracture in Al: quantum mechanical vs. empirical\n  atomistic description: A comparative study of fracture in Al is carried out by using quantum\nmechanical and empirical atomistic description of atomic interaction at crack\ntip. The former is accomplished with the density functional theory (DFT) based\nQuasicontinuum method (QCDFT) and the latter with the original Quasicontinuum\nmethod (EAM-QC). Aside from quantitative differences, the two descriptions also\nyield qualitatively distinctive fracture behavior. While EAM-QC predicts a\nstraight crack front and a micro-twinning at the crack tip, QCDFT finds a more\nrounded crack profile and the absence of twinning. Although many dislocations\nare emitted from the crack tip in EAM-QC, they all glide on a single slip\nplane. In contrast, only two dislocations are nucleated under the maximum load\napplied in QCDFT, and they glide on two adjacent slip planes. The electron\ncharge density develops sharp corners at the crack tip in EAM-QC, while it is\nsmoother in QCDFT. The physics underlying these differences is discussed."
    },
    {
        "anchor": "Laser-field detuning assisted optimization of exciton valley dynamics in\n  monolayer WSe$_2$: Geometric quantum speed limit: Optimizing valley dynamics is an effective instrument towards precisely\nmanipulating qubit in the context of two-dimensional semiconductor. In this\nwork, we construct a comprehensive model, involving both intra- and intervalley\nchannels of excitons in monolayer WSe$_2$, and simultaneously takes the\nlight-matter interaction into account, to investigate the optimal control of\nvalley dynamics with an initial coherent excitonic state. Based on the quantum\nspeed limit (QSL) theory, we propose two optimal control schemes aiming to\nreduce the evolution time of valley dynamics reaching the target state, along\nwith to boost the evolution speed over a period of time. Further, we emphasize\nthat the implementation of dynamical optimization is closely related to the\ndetuning difference -- the difference of exciton-laser field detunings between\nthe K and K' valleys -- which is determined by the optical excitation mode and\nmagnetically-induced valley splitting. In particular, we reveal that a small\ndetuning difference drives the actual dynamical path to converge towards the\ngeodesic length between the initial and final states, allowing the system to\nevolve with the least time. Especially, in the presence of valley coherence,\nthe actual evolution time and the calculated QSL time almost coincide,\nfacilitating high fidelity in information transmission based on the valley\nqubit. Remarkably, we demonstrate an intriguing enhancement in evolution speed\nof valley dynamics, by adopting a large detuning difference, which induces an\nemerging valley polarization even without initial polarization. Our work opens\na new paradigm for optically tuning excitonic physics in valleytronic\napplications, and may also offer solutions to some urgent problems such as\nspeed limit of information transmission in qubit.",
        "positive": "Single-Atom Gating of Quantum State Superpositions: The ultimate miniaturization of electronic devices will likely require local\nand coherent control of single electronic wavefunctions. Wavefunctions exist\nwithin both physical real space and an abstract state space with a simple\ngeometric interpretation: this state space--or Hilbert space--is spanned by\nmutually orthogonal state vectors corresponding to the quantized degrees of\nfreedom of the real-space system. Measurement of superpositions is akin to\naccessing the direction of a vector in Hilbert space, determining an angle of\nrotation equivalent to quantum phase. Here we show that an individual atom\ninside a designed quantum corral can control this angle, producing arbitrary\ncoherent superpositions of spatial quantum states. Using scanning tunnelling\nmicroscopy and nanostructures assembled atom-by-atom we demonstrate how single\nspins and quantum mirages can be harnessed to image the superposition of two\nelectronic states. We also present a straightforward method to determine the\natom path enacting phase rotations between any desired state vectors. A single\natom thus becomes a real space handle for an abstract Hilbert space, providing\na simple technique for coherent quantum state manipulation at the spatial limit\nof condensed matter."
    },
    {
        "anchor": "Flux-conserving diagrammatic formulation of optical spectroscopy of open\n  quantum systems: We present a theoretical approach to optical spectroscopy of open\nnonequilibrium systems, which generalizes traditional nonlinear optical\nspectroscopy tools by imposing charge and energy conservation at all levels of\napproximation. Both molecular and radiation field degrees of freedom are\ntreated quantum mechanically. The formulation is based on the nonequilibrium\nGreen's function (NEGF) approach and a double sided Feynman diagrammatic\nrepresentation of the photon flux is developed. Numerical simulations are\npresented for a model system. Our study bridges the theoretical approaches of\nquantum transport and optical spectroscopy and establishes a firm basis for\napplying traditional tools of nonlinear optical spectroscopy in molecular\noptoelectronics.",
        "positive": "Green functions for a chain subjected to a uniformly varying field in\n  the context of electron transmission: On the basis of the tight-binding formalism and Green function technique we\nobtain all the Green functions matrix elements for a biased chain with a linear\nvariation of the electron on-site energy. Their dependence on the system\nparameters is analyzed in the context of through-molecule electron transport."
    },
    {
        "anchor": "Wigner Crystals in the lowest Landau level at low filling factors: We report on results of finite-size numerical studies of partially filled\nlowest Landau level at low electron filling factors. We find convincing\nevidence suggesting that electrons form Wigner Crystals at sufficiently low\nfilling factors, and the critical filling factor is close to 1/7. At nu=1/7 we\nfind the system undergoes a phase transition from Wigner Crystal to the\nincompressible Laughlin state when the short-range part of the Coulomb\ninteraction is modified slightly. This transition is either continuous or very\nweakly first order.",
        "positive": "Photonic assisted light trapping integrated in ultrathin crystalline\n  silicon solar cells by nanoimprint lithography: We report on the fabrication of two-dimensional periodic photonic\nnanostructures by nanoimprint lithography and dry etching, and their\nintegration into a 1-{\\mu}m-thin mono-crystalline silicon solar cell. Thanks to\nthe periodic nanopatterning, a better in-coupling and trapping of light is\nachieved, resulting in an absorption enhancement. The proposed light trapping\nmechanism can be explained as the superposition of a graded index effect and of\nthe diffraction of light inside the photoactive layer. The absorption\nenhancement is translated into a 23% increase in short-circuit current, as\ncompared to the benchmark cell, resulting in an increase in energy-conversion\nefficiency."
    },
    {
        "anchor": "Uncovering Electron-Phonon Scattering and Phonon Dynamics in Type-I Weyl\n  Semimetals: Weyl semimetals are 3D phases of matter with topologically protected states\nthat have remarkable macroscopic transport behaviors. As phonon dynamics and\nelectron-phonon scattering play a critical role in the electrical and thermal\ntransport, we pursue a fundamental understanding of the origin of these effects\nin type-I Weyl semimetals NbAs and TaAs. In the temperature-dependent Raman\nspectra of NbAs, we reveal a previously unreported Fano lineshape, a signature\nstemming from the electron-phonon interaction. Additionally, the temperature\ndependence of the $A_{1}$ phonon linewidths in both NbAs and TaAs strongly\ndeviate from the standard model of anharmonic decay. To capture the mechanisms\nresponsible for the observed Fano asymmetry and the atypical phonon linewidth,\nwe present first principles calculations of the phonon self-energy correction\ndue to the electron-phonon interaction. Finally, we investigate the\nrelationship between Fano lineshape, electron-phonon coupling, and locations of\nthe Weyl points in these materials. Through this study of the phonon dynamics\nand electron-phonon interaction in these Weyl semimetals, we consider specific\nmicroscopic pathways which contribute to the nature of their macroscopic\ntransport.",
        "positive": "Theory of exciton-electron scattering in atomically thin semiconductors: The realization of mixtures of excitons and charge carriers in van-der-Waals\nmaterials presents a new frontier for the study of the many-body physics of\nstrongly interacting Bose-Fermi mixtures. In order to derive an effective\nlow-energy model for such systems, we develop an exact diagonalization approach\nbased on a discrete variable representation that predicts the scattering and\nbound state properties of three charges in two-dimensional transition metal\ndichalcogenides. From the solution of the quantum mechanical three-body problem\nwe thus obtain the bound state energies of excitons and trions within an\neffective mass model which are in excellent agreement with Quantum Monte Carlo\npredictions. The diagonalization approach also gives access to excited states\nof the three-body system. This allows us to predict the scattering phase shifts\nof electrons and excitons that serve as input for a low-energy theory of\ninteracting mixtures of excitons and charge carriers at finite density. To this\nend we derive an effective exciton-electron scattering potential that is\ndirectly applicable for Quantum Monte-Carlo or diagrammatic many-body\ntechniques. As an example, we demonstrate the approach by studying the\nmany-body physics of exciton Fermi polarons in transition-metal\ndichalcogenides, and we show that finite-range corrections have a substantial\nimpact on the optical absorption spectrum. Our approach can be applied to a\nplethora of many-body phenomena realizable in atomically thin semiconductors\nranging from exciton localization to induced superconductivity."
    },
    {
        "anchor": "Electron spin coherence of shallow donors in natural and isotopically\n  enriched germanium: Germanium is a widely used material for electronic and optoelectronic devices\nand recently it has become an important material for spintronics and quantum\ncomputing applications. Donor spins in silicon have been shown to support very\nlong coherence times ($T_{2}$) when the host material is isotopically enriched\nto remove any magnetic nuclei. Germanium also has non-magnetic isotopes so it\nis expected to support long $T_{2}$s while offering some new properties.\nCompared to Si, Ge has a strong spin-orbit coupling, large electron\nwavefunction, high mobility, and highly anisotropic conduction band valleys\nwhich will all give rise to new physics. In this Letter, the first pulsed\nelectron spin resonance (ESR) measurements of $T_{2}$ and the spin-lattice\nrelaxation ($T_1$) times for $^{75}$As and $^{31}$P donors in natural and\nisotopically enriched germanium are presented. We compare samples with various\nlevels of isotopic enrichment and find that spectral diffusion due to $^{73}$Ge\nnuclear spins limits the coherence in samples with significant amounts of\n$^{73}$Ge. For the most highly enriched samples, we find that $T_1$ limits\n$T_2$ to $T_2 = 2T_1$. We report an anisotropy in $T_1$ and the ensemble\nlinewidths for magnetic fields oriented along different crystal axes but do not\nresolve any angular dependence to the spectral-diffusion-limited $T_2$ in\nsamples with $^{73}$Ge.",
        "positive": "Koshino-Taylor effect in graphene: We discuss the phonon-assisted scattering of electrons by defects, i.e., the\nso-called Koshino-Taylor effect, in graphene. The two-dimensional character of\ngraphene implies that the strength of the Koshino-Taylor effect can be\nconsiderably larger than in ordinary metals. We show that at finite\ntemperatures the defect-induced resistivity formally diverges in the\nthermodynamic limit, having a non-analytic $T\\ln T$ component when finite size\neffects are taken into account."
    },
    {
        "anchor": "Comment on \"Laser refrigeration of hydrothermal nanocrystals in\n  physiological media\": The recent report on laser cooling of liquid may contradict the law of energy\nconservation.",
        "positive": "Magnetic Behavior of Superatom-Fullerene Assemblies: It has recently been possible to synthesize ordered assemblies composed of\nmagnetic superatomic clusters Ni9Te6(PEt3)8 separated by C60 and study their\nmagnetic behavior. We have carried out theoretical studies on model systems\nconsisting of magnetic superatoms separated by non-magnetic species to examine\nthe evolution in magnetic response as the nature of the magnetic superatom\n(directions of spin quantization), the strength of isotropic and anisotropic\ninteractions, the magnetic anisotropy energy, and the size of the assembly are\nvaried. We have examined square planar configurations consisting 16, 24 and 48\nsites with 8, 12 and 24 magnetic superatoms respectively. The magnetic atoms\nare allowed 2 or 5 orientations. The model Hamiltonian includes isotropic\nexchange interactions with second nearest neighbor ferromagnetic and nearest\nneighbor antiferromagnetic couplings and anisotropic Dzyaloshinskii-Moriya\ninteractions. It is shown that the inclusion of Dzyaloshinskii-Moriya\ninteraction that cause spin canting is necessary to get qualitative response as\nobserved in experiments."
    },
    {
        "anchor": "Forming and confining of dipolar excitons by quantizing magnetic fields: We show that a magnetic field perpendicular to an AlGaAs/GaAs coupled quantum\nwell efficiently traps dipolar excitons and leads to the stabilization of the\nexcitonic formation and confinement in the illumination area. Hereby, the\ndensity of dipolar excitons is remarkably enhanced up to $\\sim 10^{11}\ncm^{-2}$. By means of Landau level spectroscopy we study the density of excess\nholes in the illuminated region. Depending on the excitation power and the\napplied electric field, the hole density can be tuned over one order of\nmagnitude up to $\\sim 2.5$ $10^{11} cm^{-2}$ - a value comparable with typical\ncarrier densities in modulation-doped structures.",
        "positive": "Critical currents and giant non-dissipative drag for superfluid\n  electron-hole pairs in quantum Hall multilayers: Superfluid properties of electron-hole pairs in a quantum Hall four-layer\nsystem are investigated. The system is considered as a solid state realization\nof a two-component superfluid Bose gas with dipole-dipole interaction. One\nsuperfluid component is formed in the top bilayer and the other component - in\nthe bottom one. We obtain the dispersion equation for the collective mode\nspectrum and compute the critical parameters (the critical interlayer distance\nand the critical currents) versus the filling factor. We find that the critical\ncurrents of the components depend on each other. The maximum critical current\nof a given component can be reached if the current of the other component is\nequal to zero. The non-dissipative drag effect between the components is\nstudied. It is shown that in the system considered the drag factor is very\nlarge. Under appropriate conditions it can be about 10 per sent, that is at\nleast in three order larder than one predicted for two-component atomic Bose\ngases."
    },
    {
        "anchor": "Conditional spin counting statistics as a probe of Coulomb interaction\n  and spin-resolved bunching: Full counting statistics is a powerful tool to characterize the noise and\ncorrelations in transport through mesoscopic systems. In this work, we propose\nthe theory of conditional spin counting statistics, i.e., the statistical\nfluctuations of spin-up (down) current given the observation of the spin-down\n(up) current. In the context of transport through a single quantum dot, it is\ndemonstrated that a strong Coulomb interaction leads to a conditional spin\ncounting statistics that exhibits a substantial change in comparison to that\nwithout Coulomb repulsion. It thus can be served as an effective way to probe\nthe Coulomb interactions in mesoscopic transport systems. In case of spin\npolarized transport, it is further shown that the conditional spin counting\nstatistics offers a transparent tool to reveal the spin-resolved bunching\nbehavior.",
        "positive": "Non-Equilibrium and Quantum Coherent Phenomena in the Electromechanics\n  of Suspended Nanowires: Strong coupling between electronic and mechanical degrees of freedom is a\nbasic requirement for the operation of any nanoelectromechanical device. In\nthis Review we consider such devices and in particular investigate the\nproperties of small tunnel-junction nanostructures that contain a movable\nelement in the form of a suspended nanowire. In these systems, electrical\ncurrent and charge can be concentrated to small spatial volumes resulting in\nstrong coupling between the mechanics and the charge transport. As a result, a\nvariety of mesoscopic phenomena appear, which can be used for the transduction\nof electrical currents into mechanical operation. Here we will in particular\nconsider nanoelectromechanical dynamics far from equilibrium and the effect of\nquantum coherence in both the electronic and mechanical degrees of freedom in\nthe context of both normal and superconducting nanostructures."
    },
    {
        "anchor": "Light-to-heat conversion of optically trapped hot Brownian particles: Anisotropic hybrid nanostructures stand out as promising therapeutic agents\nin photothermal conversion-based treatments. Accordingly, understanding local\nheat generation mediated by light-to-heat conversion of absorbing\nmulticomponent nanoparticles at the single particle level have both forthwith\nbecome a subject of broad and current interest. Nonetheless, evaluating\nreliable temperature profiles around a single trapped nanoparticle is\nchallenging from all experimental, computational, and fundamental viewpoints.\nCommitted to filling this gap, the heat generation of an anisotropic hybrid\nnanostructure is explored by means of two different experimental approaches\nfrom which the local temperature is measured in a direct or indirect way, all\nin the context of the hot Brownian motion theory. The results were compared\nwith analytical results supported by the numerical computation of the\nwavelength-dependent absorption efficiencies in the discrete dipole\napproximation for scattering calculations, which has been here extended to\ninhomogeneous nanostructures. Overall, we provide a consistent and\ncomprehensive view of the heat generation in optical traps of highly absorbing\nparticles under the viewpoint of the hot Brownian motion theory.",
        "positive": "Phononic crystal waveguides for electromechanical circuits: Nanoelectromechanical systems (NEMS), utilising localised mechanical\nvibrations, were pioneered for sensors, signal processors and to study\nmacroscopic quantum mechanics. Increasingly the concept of integrating multiple\nmechanical elements via electrical/optical means has emerged as a challenge\ntowards NEMS circuits. Here we develop phononic crystal waveguides (PnC WGs),\nusing a 1-dimensional array of suspended membranes, that offer purely\nmechanical means to integrate isolated NEMS resonators. In the first steps to\nthis objective, we demonstrate the PnC WG can support and guide mechanical\nvibrations where the periodic membrane arrangement also creates a phonon\nbandgap that enables the phonon propagation velocity to be controlled.\nAdditionally embedding a phonon-cavity into the PnC allows mechanical\nvibrations in the WG to be dynamically switched or transferred to the cavity,\nillustrating the availability of WG-resonator coupling. These highly functional\ntraits of the PnC WG architecture exhibit all the ingredients necessary to\npermit the realisation of all-phononic NEMS circuits."
    },
    {
        "anchor": "Nonconventional Quantized Hall Resistances Obtained with $\u03bd= 2$\n  Equilibration in Epitaxial Graphene $p-n$ Junctions: We have demonstrated the millimeter-scale fabrication of monolayer epitaxial\ngraphene $p-n$ junction devices using simple ultraviolet photolithography,\nthereby significantly reducing device processing time compared to that of\nelectron beam lithography typically used for obtaining sharp junctions. This\nwork presents measurements yielding nonconventional, fractional multiples of\nthe typical quantized Hall resistance at $\\nu=2$ ($R_H\\approx 12906 {\\Omega}$)\nthat take the form: $\\frac{a}{b}R_H$. Here, $a$ and $b$ have been observed to\ntake on values such 1, 2, 3, and 5 to form various coefficients of $R_H$.\nAdditionally, we provide a framework for exploring future device configurations\nusing the LTspice circuit simulator as a guide to understand the abundance of\navailable fractions one may be able to measure. These results support the\npotential for drastically simplifying device processing time and may be used\nfor many other two-dimensional materials.",
        "positive": "Virtual crystal description of III-V semiconductor alloys in the tight\n  binding approach: We propose a simple and effective approach to construct the empirical\ntight-binding parameters of ternary alloys in the virtual crystal\napproximation. This combines a new, compact formulation of the strain\nparameters and a linear interpolation of the hamiltonians of binary materials\nstrained to the alloy equilibrium lattice parameter. We show that it is\npossible to obtain a perfect description of the bandgap bowing of ternary\nalloys in the InGaAsSb family of materials. Furthermore, this approach is in a\ngood agreement with supercell calculations using the same set of parameters.\nThis scheme opens a way for atomistic modeling of alloy-based opto-electronic\ndevices without extensive supercell calculations."
    },
    {
        "anchor": "Hybrid Exciton-Plasmon-Polaritons in van der Waals Semiconductor\n  Gratings: Van der Waals materials and heterostructures manifesting strongly bound room\ntemperature exciton states exhibit emergent physical phenomena and are of a\ngreat promise for optoelectronic applications. Here, we demonstrate that\nnanostructured multilayer transition metal dichalcogenides by themselves\nprovide an ideal platform for excitation and control of excitonic modes, paving\nthe way to exciton-photonics. Hence, we show that by patterning the TMDCs into\nnanoresonators, strong dispersion and avoided crossing of excitons and hybrid\npolaritons with interaction potentials exceeding 410 meV may be controlled with\ngreat precision. We further observe that inherently strong TMDC exciton\nabsorption resonances may be completely suppressed due to excitation of hybrid\nphoton states and their interference. Our work paves the way to a next\ngeneration of integrated exciton optoelectronic nano-devices and applications\nin light generation, computing, and sensing.",
        "positive": "Nonstanding spin waves in a single rectangular permalloy microstrip\n  under uniform magnetic excitation: Ferromagnetic resonance modes in a single rectangular Ni$_{80}$Fe$_{20}$\nmicrostrip were directly imaged using time-resolved scanning transmission x-ray\nmicroscopy combined with a phase-locked ferromagnetic resonance excitation\nscheme and the findings were corroborated by micromagnetic simulations.\nAlthough under uniform excitation in a single confined microstructure typically\nstanding spin waves are expected, all imaged spin waves showed a nonstanding\ncharacter both, at and off resonance, the latter being additionally detected\nwith microantenna-based ferromagnetic resonance. The effect of the edge quality\non the spin waves was observed in micromagnetic simulations."
    },
    {
        "anchor": "Improving Graphene-metal Contacts: Thermal Induced Polishing: Graphene is a very promising material for nanoelectronics applications due to\nits unique and remarkable electronic and thermal properties. However, when\ndeposited on metallic electrodes the overall thermal conductivity is\nsignificantly decreased. This phenomenon has been attributed to the mismatch\nbetween the interfaces and contact thermal resistance. Experimentally, one way\nto improve the graphene/metal contact is thorough high-temperature annealing,\nbut the detailed mechanisms behind these processes remain unclear. In order to\naddress these questions, we carried out fully atomistic reactive molecular\ndynamics simulations using the ReaxFF force field to investigate the\ninteractions between multi-layer graphene and metallic electrodes (nickel)\nunder (thermal) annealing. Our results show that the annealing induces an\nupward-downward movement of the graphene layers, causing a pile-driver-like\neffect over the metallic surface. This graphene induced movements cause a\nplanarization (thermal polishing-like effect) of the metallic surface, which\nresults in the increase of the effective graphene/metal contact area. This can\nalso explain the experimentally observed improvements of the thermal and\nelectric conductivities.",
        "positive": "Generation of current vortex by spin current in Rashba systems: Employing unbiased large-scale time-dependent density-matrix\nrenormalization-group simulations, we demonstrate the generation of a\ncharge-current vortex via spin injection in the Rashba system. The spin current\nis polarized perpendicular to the system plane and injected from an attached\nantiferromagnetic spin chain. We discuss the conversion between spin and\norbital angular momentum in the current vortex that occurs because of the\nconservation of the total angular momentum and the spin-orbit interaction. This\nis in contrast to the spin Hall effect, in which the angular-momentum\nconservation is violated. Finally, we predict the electromagnetic field that\naccompanies the vortex with regard to possible future experiments."
    },
    {
        "anchor": "Electric Field Tuning of the Rashba Effect in the Polar Perovskite\n  Structures: We show that the Rashba effect at the polar perovskite surfaces and\ninterfaces can be tuned by manipulating the two-dimensional electron gas (2DEG)\nby an applied electric field, using it to draw the 2DEG out to the surface or\npush it deeper into the bulk, thereby controlling the surface-sensitive\nphenomenon. These ideas are illustrated by a comprehensive density-functional\nstudy of the recently-discovered polar KTaO$_3$ surface. Analytical results\nobtained with a tight-binding model unravel the interplay between the various\nfactors affecting the Rashba effect such as the strength of the spin-orbit\ninteraction and the surface-induced asymmetry. Our work helps interpret the\nrecent experiments on the KTaO$_3$ surface as well as the SrTiO$_3$/LaAlO$_3$\ninterface.",
        "positive": "k.p theory for two-dimensional transition metal dichalcogenide\n  semiconductors: We present $\\mathbf{k}\\cdotp\\mathbf{p}$ Hamiltonians parametrised by {\\it ab\ninitio} density functional theory calculations to describe the dispersion of\nthe valence and conduction bands at their extrema (the $K$, $Q$, $\\Gamma$, and\n$M$ points of the hexagonal Brillouin zone) in atomic crystals of\nsemiconducting monolayer transition metal dichalcogenides. We review the\nparametrisation of the essential parts of the $\\mathbf{k}\\cdotp\\mathbf{p}$\nHamiltonians for MoS$_2$, MoSe$_2$, WS$_2$, and WSe$_2$, including the\nspin-splitting and spin-polarisation of the bands, and we discuss the\nvibrational properties of these materials. We then use\n$\\mathbf{k}\\cdotp\\mathbf{p}$ theory to analyse optical transitions in\ntwo-dimensional transition metal dichalcogenides over a broad spectral range\nthat covers the Van Hove singularities in the band structure (the $M$ points).\nWe also discuss the visualisation of scanning tunnelling microscopy maps."
    },
    {
        "anchor": "Pair emission from a relativistic domain wall in antiferromagnets: Magnon emission and excitation by a relativistic domain wall at a constant\nvelocity in antiferromagnet is theoretically studied. A pair emission due to a\nquadratic magnon coupling is shown to be dominant. The emission corresponds in\nthe comoving frame to a vacuum polarization induced by a zero-energy\ninstability of the Lorentz-boosted anomalous response function. The emission\nrate is sensitive to the magnon dispersion and wall profile, and is\nsignificantly enhanced for a thin wall with velocity close to the effective\nlight velocity. The Ohmic damping constant due to magnon excitation at low\nvelocity is calculated.",
        "positive": "Configuration-specific insight to single-molecule conductance and noise\n  data revealed by principal component projection method: We explore the merits of neural network boosted,\nprincipal-component-projection-based, unsupervised data classification in\nsingle-molecule break junction measurements, demonstrating that this method\nidentifies highly relevant trace classes according to the well-defined and\nwell-visualized internal correlations of the dataset. To this end, we\ninvestigate single-molecule structures exhibiting double molecular\nconfigurations, exploring the role of the leading principal components in the\nidentification of alternative junction evolution trajectories. We show how the\nproper principal component projections can be applied to separately analyze the\nhigh or low-conductance molecular configurations, which we exploit in\n$1/f$-type noise measurements on bipyridine molecules. This approach untangles\nthe unclear noise evolution of the entire dataset, identifying the coupling of\nthe aromatic ring to the electrodes through the $\\pi$ orbitals in two distinct\nconductance regions, and its subsequent uncoupling as these configurations are\nstretched."
    },
    {
        "anchor": "Transverse Electron Focusing in Systems with Spin-Orbit Coupling: We study the transverse electron focusing in a two dimensional electron gas\nwith Rashba spin-orbit coupling. We show that the interplay between the\nexternal magnetic field and the spin-orbit coupling gives two branches of\nstates with different cyclotron radius within the same energy window. This\neffect generates a splitting of the first focusing peak in two contributions.\nEach one of these contributions is spin polarized. The surface reflection mixes\nthe two branches and the second focusing peak does not present the same effect.\nWhile for GaAs/AlGaAs heterostructures the effect is small, in systems like\nInSb/InAlSb the effect should be clearly observed.",
        "positive": "Coherent Excitonic Coupling in an Asymmetric Double InGaAs Quantum Well\n  Arises from Many-Body Effects: We study an asymmetric double InGaAs quantum well using optical\ntwo-dimensional coherent spectroscopy. The collection of zero-quantum,\none-quantum, and two-quantum two-dimensional spectra provides a unique and\ncomprehensive picture of the double well coherent optical response. Coherent\nand incoherent contributions to the coupling between the two quantum well\nexcitons are clearly separated. An excellent agreement with density matrix\ncalculations reveals that coherent interwell coupling originates from many-body\ninteractions."
    },
    {
        "anchor": "Coherent control of correlated nanodevices: A hybrid time-dependent\n  numerical renormalization-group approach to periodic switching: The time-dependent numerical renormalization-group approach (TD-NRG),\noriginally devised for tracking the real-time dynamics of quantum-impurity\nsystems following a single quantum quench, is extended to multiple switching\nevents. This generalization of the TD-NRG encompasses the possibility of\nperiodic switching, allowing for coherent control of strongly correlated\nsystems by an external time-dependent field. To this end, we have embedded the\nTD-NRG in a hybrid framework that combines the outstanding capabilities of the\nnumerical renormalization group to systematically construct the effective\nlow-energy Hamiltonian of the system with the prowess of complementary\napproaches for calculating the real-time dynamics derived from this\nHamiltonian. We demonstrate the power of our approach by hybridizing the TD-NRG\nwith the Chebyshev expansion technique in order to investigate periodic\nswitching in the interacting resonant-level model. Although the interacting\nmodel shares the same low-energy fixed point as its noninteracting counterpart,\nwe surprisingly find the gradual emergence of damped oscillations as the\ninteraction strength is increased. Focusing on a single quantum quench and\nusing a strong-coupling analysis, we reveal the origin of these\ninteraction-induced oscillations and provide an analytical estimate for their\nfrequency. The latter agrees well with the numerical results.",
        "positive": "Real-Time Quantum Dynamics of Long-Range Electronic Excitation Transfer\n  in Plasmonic Nanoantennas: Using large-scale, real-time quantum dynamics calculations, we present a\ndetailed analysis of electronic excitation transfer (EET) mechanisms in a\nmulti-particle plasmonic nanoantenna system. Specifically, we utilize\nreal-time, time-dependent, density functional tight binding (RT-TDDFTB) to\nprovide a quantum-mechanical description (at an electronic/atomistic level of\ndetail) for characterizing and analyzing these systems, without recourse to\nclassical approximations. We also demonstrate highly long-range electronic\ncouplings in these complex systems and find that the range of these couplings\nis more than twice the conventional cutoff limit considered by FRET based\napproaches. Furthermore, we attribute these unusually long-ranged electronic\ncouplings to the coherent oscillations of conduction electrons in plasmonic\nnanoparticles. This long-range nature of plasmonic interactions has important\nramifications for EET - in particular, we show that the commonly used\n\"nearest-neighbor\" FRET model is inadequate for accurately characterizing EET\neven in simple plasmonic antenna systems. These findings provide a real-time,\nquantum-mechanical perspective for understanding EET mechanisms and provide\nguidance in enhancing plasmonic properties in artificial light-harvesting\nsystems."
    },
    {
        "anchor": "Spin projected unrestricted Hartree-Fock ground states for harmonic\n  quantum dots: We report results for the ground state energies and wave functions obtained\nby projecting spatially unrestricted Hartree Fock states to eigenstates of the\ntotal spin and the angular momentum for harmonic quantum dots with $N\\leq 12$\ninteracting electrons including a magnetic field states with the correct\nspatial and spin symmetries have lower energies than those obtained by the\nunrestricted method. The chemical potential as a function of a perpendicular\nmagnetic field is obtained. Signature of an intrinsic spin blockade effect is\nfound.",
        "positive": "Localization counteracts decoherence in noisy Floquet topological chains: The topological phases of periodically-driven, or Floquet systems, rely on a\nperfectly periodic modulation of system parameters in time. Even the smallest\ndeviation from periodicity leads to decoherence, causing the boundary (end)\nstates to leak into the system's bulk. Here, we show that in one dimension this\ndecay of topologically protected end states depends fundamentally on the nature\nof the bulk states: a dispersive bulk results in an exponential decay, while a\nlocalized bulk slows the decay down to a diffusive process. The localization\ncan be due to disorder, which remarkably counteracts decoherence even when it\nbreaks the symmetry responsible for the topological protection. We derive this\nresult analytically, using a novel, discrete-time Floquet-Lindblad formalism\nand confirm out findings with the help of numerical simulations. Our results\nare particularly relevant for experiments, where disorder can be tailored to\nprotect Floquet topological phases from decoherence."
    },
    {
        "anchor": "Superlattice nanowire heat engines with direction-dependent power output\n  and heat current: Heat engines (HEs) made of low dimensional structures offer promising\napplications in energy harvesting due to their reduced phonon thermal\nconductance. Many efforts have been devoted to the design of HEs made of\nquantum-dot (QD) superlattice nanowire (SLNW), but only SLNWs with uniform\nenergy levels in QDs were considered. Here we propose a HE made of SLNW with\nstaircase-like QD energy levels. It is demonstrated that the nonlinear Seebeck\neffect can lead to significant electron transports for such a nanowire with\nstaircase-like energy levels. The asymmetrical alignment of energy levels of\nquantum dots embedded in nanowires can be controlled to allow resonant electron\ntransport under forward temperature bias, while they are in off-resonant regime\nunder backward bias. Under such a mechanism,the power output and efficiency of\nsuch a SLNW are better than SLNWs with uniform QD energy levels. The SLNW HE\nhas direction-dependent power output and heat current. In addition, the HE has\nthe functionality of a heat diode with impressive negative differential thermal\nconductance under open circuit condition.",
        "positive": "Proposal for THz lasing from a topological quantum dot: Topological quantum dots (TQDs) are 3D topological insulator nanoparticles\nwith radius below 100 nm, which display symmetry-protected surface states with\ndiscretized energies. We propose a scheme which harnesses these energy levels\nin a closed lasing scheme, in which a single TQD, when pumped with incoherent\nTHz light, lases from its surface states in the THz regime. The time scales\nassociated with the system are unusually slow, and lasing occurs with a very\nlow threshold. Due to the low threshold, we predict that blackbody radiation at\nroom-temperature provides enough photons to pump the system, providing a route\nto room-temperature THz lasing with blackbody radiation as the pump."
    },
    {
        "anchor": "LO-phonon emission rate of hot electrons from an on-demand\n  single-electron source in a GaAs/AlGaAs heterostructure: Using a recently-developed time-of-flight measurement technique with 1 ps\ntime resolution and electron-energy spectroscopy, we developed a method to\nmeasure the longitudinal-optical-phonon emission rate of hot electrons\ntravelling along a depleted edge of a quantum Hall bar. A comparison of the\nexperimental results to a single-particle model implies that the main\nscattering mechanism involves a two-step process via intra-Landau-level\ntransition. We show this scattering can be suppressed by controlling the edge\npotential profile, and a scattering length > 1 mm can be achieved, allowing the\nuse of this system for scalable single-electron device applications.",
        "positive": "Topological Dipole Insulator: We expand the concept of two-dimensional topological insulators to encompass\na novel category known as topological dipole insulators (TDIs), characterized\nby conserved dipole moments along the $x$-direction in addition to charge\nconservation. By generalizing Laughlin's flux insertion argument, we prove a\nno-go theorem and predict possible edge patterns and anomalies in a TDI with\nboth charge $U^e(1)$ and dipole $U^d(1)$ symmetries. The edge of a TDI is\ncharacterized as a quadrupolar channel that displays a dipole $U^d(1)$ anomaly.\nA quantized amount of dipole gets transferred between the edges under the\ndipolar flux insertion, manifesting as `quantized quadrupolar Hall effect' in\nTDIs. A microscopic coupled-wire Hamiltonian realizing the TDI is constructed\nby introducing a mutually commuting pair-hopping terms between wires to gap out\nall the bulk modes while preserving the dipole moment. The effective action at\nthe quadrupolar edge can be derived from the wire model, with the corresponding\nbulk dipolar Chern-Simons response theory delineating the topological\nelectromagnetic response in TDIs. Finally, we enrich our exploration of\ntopological dipole insulators to the spinful case and construct a dipolar\nversion of the quantum spin Hall effect, whose boundary evidences a mixed\nanomaly between spin and dipole symmetry. Effective bulk and the edge action\nfor the dipolar quantum spin Hall insulator are constructed as well."
    },
    {
        "anchor": "Fourier transform analysis of irradiated Weiss oscillations: We present a theoretical approach to study the effect of microwave radiation\non the magnetoresistance of a one-dimensional superlattice.\n  In our proposal the magnetoresistance of a unidirectional spatial periodic\npotential (superlattice), is modulated by microwave radiation due to an\ninterference effect between both, space and time-dependent potentials. The\nfinal magnetoresistance will mainly depend on the spatial period of the\nsuperlattice and the radiation frequency. %Then, by tuning either the spatial\nperiod of the superlattice or the radiation %frequency, the magnetoresistance\ncan be strongly modified. We consider an approach to study these effects based\non the fast Fourier transform of the obtained magnetorresistance profiles in\nfunction of the inverse of the magnetic field. Based on this theory we propose\nthe design of a novel radiation sensor for the Terahertz band.} % We first\nstudy the FFT of the system for each potential individually. Then we study\njointly the FFT of the system when the two types of potentials are\nsimultaneously acting.",
        "positive": "Thermally driven pure spin and valley current via anomalous Nernst\n  effect in monolayer group-VI dichalcogenides: Spin and valley dependent anomalous Nernst effect are analyzed for monolayer\nMoS2 and other group-VI dichalcogenides. We find that pure spin and valley\ncurrents can be generated perpendicular to the applied thermal gradient in the\nplane of these two-dimensional materials. This effect provides a versatile\nplatform for applications of spin caloritronics. A spin current purity factor\nis introduced to quantify this effect. When time reversal symmetry is violated,\ne.g. two-dimensional materials on an insulating magnetic substrate, a dip-peak\nfeature appears for the total Nernst coefficient. For the dip state it is found\nthat carriers with only one spin and from one valley are driven by the\ntemperature gradient."
    },
    {
        "anchor": "Fermionic vs. bosonic thermalization in the phonon-driven exciton\n  dynamics: An analytic dimensionality study: Excitons are compound particles formed from an electron and a hole in\nsemiconductors. The impact of this substructure on the phonon-exciton\ninteraction is described by a closed system of microscopic scattering\nequations. To calculate the actual excitonic thermalization properties beyond\nthe pure bosonic picture, this equation is derived directly from an\nelectron-hole picture within the Heisenberg equation of motion framework. In\naddition to the well-known bosonic character of the compound particles, we\nidentified processes of a repulsive, fermionic type, as well as attractive\ncarrier exchange contributing to the scattering process. In this analytical\nstudy we give general statements about the thermalization of excitons in two\nand three dimensional semiconductors. We give insights on the strong dependence\nof the thermalization characteristics of the exciton Bohr radius and the\nthermalization wavelength. Above all, we analytically provide arguments why a\nbosonic behavior of excitons - such as an enhanced ground state occupation -\nrequires the dominant phonon scattering to be quasielastic. Acoustic phonons\ntend to fulfil this, as each scattering event only takes small amounts of\nenergy out of the distribution, while optical phonons tend to prevent\nmacroscopic occupations of the lowest exciton state, since the Pauli repulsion\nbetween the individual carriers will then dominate the thermalization dynamics.",
        "positive": "Landau Levels of the Euler Class Topology: Two-dimensional systems with $C_{2}\\mathcal{T}$ ($P\\mathcal{T}$) symmetry\nexhibit the Euler class topology $E\\in\\mathbb{Z}$ in each two-band subspace\nrealizing a fragile topology beyond the symmetry indicators. By systematically\nstudying the energy levels of Euler insulating phases in the presence of an\nexternal magnetic field, we reveal the robust gaplessness of the Hofstadter\nbutterfly spectrum in the flat-band limit, while for the dispersive bands the\ngapping of the Landau levels is controlled by a hidden symmetry. We also find\nthat the Euler class $E$ of a two-band subspace gives a lower bound for the\nChern numbers of the magnetic subgaps. Our study provides new fundamental\ninsights into the fragile topology of flat-band systems going beyond the\nspecial case of $E=1$ as e.g.~in twisted bilayer graphene, thus opening the way\nto a very rich, still mainly unexplored, topological landscape with higher\nEuler classes."
    },
    {
        "anchor": "Evidence of magnetic field quenching of phosphorous-doped silicon\n  quantum dots: We present data on the electrical transport properties of highly-doped\nsilicon-on-insulator quantum dots under the effect of pulsed magnetic fields up\nto 48 T. At low field intensities, B<7 T, we observe a strong modification of\nthe conductance due to the destruction of weak localization whereas at higher\nfields, where the magnetic field length becomes comparable to the effective\nBohr radius of phosphorous in silicon, a strong decrease in conductance is\ndemonstrated. Data in the high and low electric field bias regimes are then\ncompared to show that close to the Coulomb blockade edge magnetically-induced\nquenching to single donors in the quantum dot is achieved at about 40 T.",
        "positive": "Transition from Free to Interacting Composite Fermions away from\n  $\u03bd$=1/3: Spin excitations from a partially populated composite fermion level are\nstudied above and below $\\nu=1/3$. In the range $2/7<\\nu<2/5$ the experiments\nuncover significant departures from the non-interacting composite fermion\npicture that demonstrate the increasing impact of interactions as quasiparticle\nLandau levels are filled. The observed onset of a transition from free to\ninteracting composite fermions could be linked to condensation into the higher\norder states suggested by transport experiments and numerical evaluations\nperformed in the same filling factor range."
    },
    {
        "anchor": "Topological low-energy modes in N=0 Landau levels of graphene: a\n  possibility of a quantum-liquid ground state: We point out that the zero-energy Landau level of Dirac fermions in graphene\ncan be, in the presence of a repulsive electron-electron interaction, split\ninto two (levels) associated with a \"bond ordering\" formation having a \"Kekule\npattern\", which respects the chiral symmetry. Since the Kekule pattern has a\nthree-fold degeneracy, domain structures are implied, for which we show that\nin-gap states localized along the domain boundaries exist as topological\nstates. Based on this a possibility of a quantum-liquid ground state of\ngraphene in magnetic fields is discussed.",
        "positive": "Thermal mirror buckling in freestanding graphene locally controlled by\n  scanning tunneling microscopy: Knowledge of and control over the curvature of ripples in freestanding\ngraphene are desirable for fabricating and designing flexible electronic\ndevices, and recent progress in these pursuits has been achieved using several\nadvanced techniques such as scanning tunneling microscopy. The electrostatic\nforces induced through a bias voltage (or gate voltage) were used to manipulate\nthe interaction of freestanding graphene with a tip (substrate). Such forces\ncan cause large movements and sudden changes in curvature through mirror\nbuckling. Here we explore an alternative mechanism, thermal load, to control\nthe curvature of graphene. We demonstrate thermal mirror buckling of graphene\nby scanning tunneling microscopy and large-scale molecular dynamic simulations.\nThe negative thermal expansion coefficient of graphene is an essential\ningredient in explaining the observed effects. This new control mechanism\nrepresents a fundamental advance in understanding the influence of temperature\ngradients on the dynamics of freestanding graphene and future applications with\nelectro-thermal-mechanical nanodevices."
    },
    {
        "anchor": "Dual-path state reconstruction scheme for propagating quantum microwaves\n  and detector noise tomography: Quantum state reconstruction involves measurement devices that are usually\ndescribed by idealized models, but not known in full detail in experiments. For\nweak propagating microwaves, the detection process requires linear amplifiers\nwhich obscure the signal with random noise. Here, we introduce a theory which\nnevertheless allows one to use these devices for measuring all quadrature\nmoments of propagating quantum microwaves based on cross-correlations from a\ndual-path amplification setup. Simultaneously, the detector noise properties\nare determined, allowing for tomography. We demonstrate the feasibility of our\nnovel concept by proof-of-principle experiments with classical mixtures of weak\ncoherent microwaves.",
        "positive": "Surface-state spin textures in strained bulk HgTe: strain-induced\n  topological phase transitions: The opening of a band gap due to compressive uniaxial strain renders bulk\nHgTe a strong three-dimensional topological insulators with protected gapless\nsurface states at any surface. By employing a six-band k.p model, we determine\nthe spin textures of the topological surface states of strained HgTe using\ntheir close relations with the mirror Chern numbers of the system and the\norbital composition of the surface states. We show that at surfaces with C2v\npoint group symmetry an increase in the strain magnitude triggers a topological\nphase transition where the winding number of the surface state spin texture is\nflipped while the four topological invariants characterizing the bulk band\nstructure of the material are unchanged."
    },
    {
        "anchor": "Electron g-factor determined for quantum dot circuit fabricated from\n  (110)-oriented GaAs quantum well: The choice of substrate orientation for semiconductor quantum dot circuits\noffers opportunities for tailoring spintronic properties such as g-factors for\nspecific functionality. In this letter, we demonstrate the operation of a\nfew-electron double quantum dot circuit fabricated from a (110)-oriented GaAs\nquantum well. We estimate the in-plane electron g-factor from the profile of\nthe enhanced inter-dot tunneling (leakage) current near zero magnetic field.\nSpin-blockade due to Pauli exclusion can block inter-dot tunneling. However,\nthis blockade becomes inactive due to hyperfine interaction mediated spin\nflip-flop processes between electron spin states and the nuclear spin of the\nhost material. The g-factor of absolute value ~0.1 found for a magnetic field\nparallel to the direction [11(bar)0], is approximately a factor of four lower\nthan that for comparable circuits fabricated from material grown on\nwidely-employed standard (001) GaAs substrates, and is in line with reported\nvalues determined by purely optical means for quantum well structures grown on\n(110) GaAs substrates.",
        "positive": "Holonomic quantum manipulation in the Weyl Disk: It has been shown that a Weyl point in a superconducting nanostructure may\ngive rise to a Weyl disk where two quantum states are almost degenerate in a 2D\nmanifold in the parametric space. This opens up the possibility of a holonomic\nquantum manipulation: a transformation of the wave function upon adiabatic\nchange of the parameters within the degenerate manifold. In this paper, we\ninvestigate in detail the opportunities for holonomic manipulation in Weyl\ndisks.\n  We compute the connection at the manifold in quasiclassical approximation to\nshow it is Abelian and can be used for a phase gate. To provide a closed\nexample of quantum manipulation that includes a state preparation and read-out,\nwe augment the holonomic gate with a change of parameters that brings the\nsystem out of the degenerate subspace. For numerical illustrations, we use a\nfinite value of quasiclassical parameter and exact quantum dynamics. We\ninvestigate the fidelity of an example gate for different execution times."
    },
    {
        "anchor": "Momentum dependence of spin-orbit interaction effects in single-layer\n  and multi-layer transition metal dichalcogenides: One of the main characteristics of the new family of two-dimensional crystals\nof semiconducting transition metal dichalcogenides (TMD) is the strong\nspin-orbit interaction, which makes them very promising for future applications\nin spintronics and valleytronics devices. Here we present a detailed study of\nthe effect of spin-orbit coupling (SOC) on the band structure of single-layer\nand bulk TMDs, including explicitly the role of the chalcogen orbitals and\ntheir hybridization with the transition metal atoms. To this aim, we combine\ndensity functional theory (DFT) calculations with a Slater-Koster tight-binding\nmodel. Whereas most of the previous tight-binding models have been restricted\nto the K and K' points of the Brillouin zone (BZ), here we consider the effect\nof SOC in the whole BZ, and the results are compared to the band structure\nobtained by DFT methods. The tight-binding model is used to analyze the effect\nof SOC in the band structure, considering separately the contributions from the\ntransition metal and the chalcogen atoms. Finally, we present a scenario where,\nin the case of strong SOC, the spin/orbital/valley entanglement at the minimum\nof the conduction band at Q can be probed and be of experimental interest in\nthe most common cases of electron-doping reported for this family of compounds.",
        "positive": "Geometry controlled superconducting diode and anomalous Josephson effect\n  triggered by the topological phase transition in curved proximitized\n  nanowires: We study the key features of the Josephson transport through a curved\nsemiconducting nanowire. Based on numerical simulations and analytical\nestimates within the framework of the Bogoliubov-de Gennes equations we find\nthe ground-state phase difference $\\varphi_0$ between the superconducting leads\ntuned by the spin splitting field $h$ driving the system from the topologically\ntrivial to the nontrivial superconducting state. The phase $\\varphi_0$ vanishes\nfor rather small $h$, grows in a certain field range around the topological\ntransition, and then saturates at large $h$ in the Kitaev regime. Both the\nsubgap and the continuum quasiparticle levels are responsible for the above\nbehavior of the anomalous Josephson phase. It is demonstrated that the\ncrossover region on $\\varphi_0(h)$ dependencies reveals itself in the\nsuperconducting diode effect. The resulting tunable phase battery can be used\nas a probe of topological transitions in Majorana networks and can become a\nuseful element of various quantum computation devices."
    },
    {
        "anchor": "Theory of anisotropic Rashba splitting of surface states: We investigate the surface Rashba effect for a surface of reduced in-plane\nsymmetry. Formulating a k.p perturbation theory, we show that the Rashba\nsplitting is anisotropic, in agreement with symmetry-based considerations. We\nshow that the anisotropic Rashba splitting is due to the admixture of bulk\nstates of different symmetry to the surface state, and it cannot be explained\nwithin the standard theoretical picture supposing just a normal-to-surface\nvariation of the crystal potential. Performing relativistic ab initio\ncalculations we find a remarkably large Rashba anisotropy for an\nunreconstructed Au(110) surface that is in the experimentally accessible range.",
        "positive": "Role of isotropic and anisotropic Dzyaloshinskii-Moriya interaction on\n  skyrmions, merons and antiskyrmions in the $C_{nv}$ symmetric system: The lattice Hamiltonian with the presence of a chiral magnetic isotropic\nDzyaloshinskii-Moriya interaction (DMI) in a square and hexagonal lattice is\nnumerically solved to give the full phase diagram consisting of skyrmions and\nmerons in different parameter planes. The phase diagram provides the actual\nregions of analytically unresolved asymmetric skyrmions and merons, and it is\nfound that these regions are substantially larger than those of symmetric\nskyrmions and merons. With magnetic field, a change from meron or spin spiral\nto skyrmion is seen. The complete phase diagram for the $C_{nv}$ symmetric\nsystem with anisotropic DMI is drawn and it is shown that this DMI helps to\nchange the spin spiral propagation direction. Finally, the well-defined region\nof a thermodynamically stable antiskyrmion phase in the $C_{nv}$ symmetric\nsystem is shown."
    },
    {
        "anchor": "GFET Lab: A Graphene Field-Effect Transistor TCAD Tool: Graphene field-effect transistors (GFETs) are experimental devices which are\nincreasingly seeing commercial and research applications. Simulation and\nmodelling forms an important stage in facilitating this transition, however the\nmajority of GFET modelling relies on user implementation. To this end, we\npresent GFET Lab, a user-friendly, open-source software tool for simulating\nGFETs.\n  We first provide an overview of approaches to device modelling and a brief\nsurvey of GFET compact models and limitations. From this survey, we identify\nthree key criteria for a suitable predictive model for circuit design: it must\nbe a compact model; it must be SPICE-compatible; it must have a minimal number\nof fitting parameters. We selected Jimenez's drain-current model as it best\nmatched these criteria, and we introduce some modifications to improve the\npredictive properties, namely accounting for saturation velocity and the\nasymmetry in n- and p-type carrier mobilities.\n  We then validate the model by comparing GFETs simulated in our tool against\nexperimentally-obtained GFET characteristics with the same materials and\ngeometries and find good agreement between GFET Lab and experiment. We\ndemonstrate the ability to export SPICE models for use in higher level circuit\nsimulations and compare SPICE simulations of GFETs against GFETs simulated in\nGFET Lab, again showing good agreement.\n  Lastly, we provide a brief tutorial of GFET Lab to demonstrate and encourage\nits use as a community-developed piece of software with both research and\neducational applications.",
        "positive": "Steady state current fluctuations and dynamical control in a\n  nonequilibrium single-site Bose-Hubbard system: We investigate nonequilibrium energy transfer in a single-site Bose-Hubbard\nmodel coupled to two thermal baths. By including a quantum kinetic equation\ncombined with full counting statistics, we investigate the steady state energy\nflux and noise power. The influence of the nonlinear Bose-Hubbard interaction\non the transfer behaviors is analyzed, and the nonmonotonic features are\nclearly exhibited. Particularly, in the strong on-site repulsion limit, the\nresults become identical with the nonequilibrium spin-boson model. We also\nextend the quantum kinetic equation to study the geometric-phase-induced energy\npump. An interesting reversal behavior is unraveled by enhancing the\nBose-Hubbard repulsion strength."
    },
    {
        "anchor": "Disorder effect on magneto-transport on the surface of a topological\n  insulator: We study the magneto-transport properties on the disordered surface of a\ntopological insulator attached with a ferromagnet/ferromagnet junction. Since,\nin the surface Dirac Hamiltonian, out-of-plane magnetization induces a mass\ngap, while in-plane magnetization has a role of the effective vector potential,\nthe mechanism of magneto-transport is different between these two cases. The\nformer is similar to the conventional one in ferromagnetic metals, while the\nlatter is due to the shift of Fermi circles in momentum space. Our numerical\ncalculations show that the magnetoconductance in in-plane configuration is\nrobust against disorder compared to that in out-of-plane configuration.",
        "positive": "Phase dependent Andreev spectrum in a difusive SNS junction. Static and\n  dynamic current response: A long phase coherent normal (N) wire between superconductors (S) is\ncharacterized by a dense phase dependent Andreev spectrum. We investigate the\ncurrent response of Andreev states of an NS ring to a time dependent Aharonov\nBohm flux superimposed to a dc one. The ring is modeled with a tight binding\nHamiltonian including a superconducting region with a BCS coupling between\nelectron and hole states, in contact with a normal region with on site\ndisorder. Both dc and ac currents are determined from the computed eigenstates\nand energies using a Kubo formula approach. Beside the well known Josephson\ncurrent we identify different contributions to the ac response. A low frequency\none related to the dynamics of the thermal occupations of the Andreev states\nand a higher frequency one related to microwave induced transitions between\nlevels. Both are characterized by strongly anharmonic phase dependencies which\nare nearly opposite to one another. Our findings are successfully compared to\nthe results of recent experiments."
    },
    {
        "anchor": "Extraordinary Photon Transport by Near-Field Coupling of a\n  Nanostructured Metamaterial with a Graphene-Covered Plate: Coupled surface plasmon/phonon polaritons and hyperbolic modes are known to\nenhance radiative transport across nanometer vacuum gaps but usually require\nidentical materials. It becomes crucial to achieve strong near-field energy\ntransfer between dissimilar materials for applications like near-field\nthermophotovoltaic and thermal rectification. In this work, we theoretically\ndemonstrate extraordinary near-field radiative transport between a\nnanostructured metamaterial emitter and a graphene-covered planar receiver.\nStrong near-field coupling with two orders of magnitude enhancement in the\nspectral heat flux is achieved at the gap distance of 20 nm. By carefully\nselecting the graphene chemical potential and doping levels of silicon nanohole\nemitter and silicon plate receiver, the total near-field radiative heat flux\ncan reach about 500 times higher than the far-field blackbody limit between 400\nK and 300 K. The physical mechanisms are elucidated by the near-field surface\nplasmon coupling with fluctuational electrodynamics and dispersion relations.\nThe effects of graphene chemical potential, emitter and receiver doping levels,\nand vacuum gap distance on the near-field coupling and radiative transfer are\nanalyzed in detail.",
        "positive": "Quantum interference in an interfacial superconductor: The two-dimensional superconductor formed at the interface between the\ncomplex oxides, lanthanum aluminate (LAO) and strontium titanate (STO) has\nseveral intriguing properties that set it apart from conventional\nsuperconductors. Most notably, an electric field can be used to tune its\ncritical temperature (T$_c$), revealing a dome-shaped phase diagram reminiscent\nof high T$_c$ superconductors. So far, experiments with oxide interfaces have\nmeasured quantities which probe only the magnitude of the superconducting order\nparameter and are not sensitive to its phase. Here, we perform phase-sensitive\nmeasurements by realizing the first superconducting quantum interference\ndevices (SQUIDs) at the LAO/STO interface. Furthermore, we develop a new\nparadigm for the creation of superconducting circuit elements, where local\ngates enable in-situ creation and control of Josephson junctions. These\ngate-defined SQUIDs are unique in that the entire device is made from a single\nsuperconductor with purely electrostatic interfaces between the superconducting\nreservoir and the weak link. We complement our experiments with numerical\nsimulations and show that the low superfluid density of this interfacial\nsuperconductor results in a large, gate-controllable kinetic inductance of the\nSQUID. Our observation of robust quantum interference opens up a new pathway to\nunderstand the nature of superconductivity at oxide interfaces."
    },
    {
        "anchor": "A dynamical model for Brownian molecular motors driven by inelastic\n  electron tunneling: In recent years, several artificial molecular motors driven and controlled by\nelectric currents have been proposed. Similar to Brownian machines, these\nsystems work by turning random inelastic tunneling events into a directional\nrotation of the molecule. Despite their importance as the ultimate component of\nfuture molecular machines, their modeling has not been sufficiently studied.\nHere, we develop a dynamical model to describe these systems. We illustrate the\nvalidity and usefulness of our model by applying it to a well-known molecular\nmotor, showing that the obtained results are consistent with the available\nexperimental data. Moreover, we demonstrate how to use our model to extract\nsome difficult-to-access microscopic parameters. Finally, we include an\nanalysis of the expected effects of current-induced forces (CIFs). Our analysis\nsuggests that, although nonconservative contributions of the CIFs can be\nimportant in some scenarios, they do not seem important in the analyzed case.\nDespite this, the conservative contributions of CIFs could be strong enough to\nsignificantly alter the system's dynamics.",
        "positive": "Waves of spin-current in magnetized dielectrics: Spin-current is an important physical quantity in present day spintronics and\nit might be very usefull in the physics of quantum plasma of spinning\nparticles. Thus it is important to have an equation of the spin-current\nevolution. This equation naturally appears as a part of a set of the quantum\nhydrodynamics (QHD) equations. Consequently, we present the set of the QHD\nequations derived from the many-particle microscopic Schrodinger equation,\nwhich consists of the continuity equation, the Euler equation, the Bloch\nequation and equation of the spin-current evolution. We use these equations to\nstudy dispersion of the collective excitations in the three dimensional samples\nof the magnetized dielectrics. We show that dynamics of the spin-current leads\nto formation of new type of the collective excitations in the magnetized\ndielectrics, which we called spin-current waves."
    },
    {
        "anchor": "Long coherence of electron spins coupled to a nuclear spin bath: Qubits, the quantum mechanical bits required for quantum computing, must\nretain their fragile quantum states over long periods of time. In many types of\nelectron spin qubits, the primary source of decoherence is the interaction\nbetween the electron spins and nuclear spins of the host lattice. For electrons\nin gate defined GaAs quantum dots, previous spin echo measurements have\nrevealed coherence times of about 1 $\\mu$s at low magnetic fields below 100 mT.\nHere, we show that coherence in such devices can actually survive to much\nlonger times, and provide a detailed understanding of the measured nuclear spin\ninduced decoherence. At fields above a few hundred millitesla, the coherence\ntime measured using a single-pulse spin echo extends to 30 $\\mu$s. At lower\nmagnetic fields, the echo first collapses, but then revives at later times\ngiven by the period of the relative Larmor precession of different nuclear\nspecies. This behavior was recently predicted, and as we show can be\nquantitatively accounted for by a semi-classical model for the electron spin\ndynamics in the presence of a nuclear spin bath. Using a multiple-pulse\nCarr-Purcell-Meiboom-Gill echo sequence, the decoherence time can be extended\nto more than 200 $\\mu$s, which represents an improvement by two orders of\nmagnitude compared to previous measurements. This demonstration of effective\nmethods to mitigate nuclear spin induced decoherence puts the quantum error\ncorrection threshold within reach.",
        "positive": "Observation of the Bloch-Siegert shift in a driven quantum-to-classical\n  transition: We show that the counter-rotating terms of the dispersive qubit-cavity Rabi\nmodel can produce relatively large and nonmonotonic Bloch-Siegert shifts in the\ncavity frequency as the system is driven through a quantum-to-classical\ntransition. Using a weak microwave probe tone, we demonstrate experimentally\nthis effect by monitoring the resonance frequency of a microwave cavity coupled\nto a transmon and driven by a microwave field with varying power. In the weakly\ndriven regime (quantum phase), the Bloch-Siegert shift appears as a small\nconstant frequency shift, while for strong drive (classical phase) it presents\nan oscillatory behaviour as a function of the number of photons in the cavity.\nThe experimental results are in agreement with numerical simulations based on\nthe quasienergy spectrum."
    },
    {
        "anchor": "Quantum Fingerprints in Higher Order Correlators of a Spin Qubit: The spin of an electron in a semiconductor quantum dot represents a natural\nnanoscale solid state qubit. Coupling to nuclear spins leads to decoherence\nthat limits the number of allowed quantum logic operations for this qubit.\nTraditional approach to characterize decoherence is to explore spin Relaxation\nand the spin echo, which are equivalent to the studies of the spins 2nd order\ntime-correlator at various external conditions. Here we develop an alternative\ntechnique by showing that considerable information about dynamics can be\nobtained from direct measurements of higher than the 2nd order correlators,\nwhich to date have been hindered in semiconductor quantum dots. We show that\nsuch correlators are sensitive to pure quantum effects that cannot be explained\nwithin the classical framework, and which allow direct determination of\nensemble and quantum dephasing times with only repeated projective measurements\nwithout the need for coherent spin control. Our method enables studies of pure\nquantum effects, including tests of the Leggett-Garg type inequalities that\nrule out local hidden variable interpretation of the spin qubit dynamics.",
        "positive": "Entropy and information flow in quantum systems strongly coupled to\n  baths: Considering von Neumann expression for reduced density matrix as\nthermodynamic entropy of a system strongly coupled to baths, we use\nnonequilibrium Green's function (NEGF) techniques to derive bath and energy\nresolved expressions for entropy, entropy production, and information flows.\nThe consideration is consistent with dynamic (quantum transport) description\nand expressions reduce to expected forms in limiting cases of weak coupling or\nsteady-state. Formulation of the flows in terms of only system degrees freedom\nis convenient for simulation of thermodynamic characteristics of open\nnonequilibrium quantum systems. We utilize standard NEGF for derivations in\nnoninteracting systems, Hubbard NEGF is used for interacting systems.\nTheoretical derivations are illustrated with numerical simulations within\ngeneric junction models."
    },
    {
        "anchor": "Unifying semiclassics and quantum perturbation theory at nonlinear order: Nonlinear electrical response permits a unique window into effects of band\nstructure geometry. It can be calculated either starting from a Boltzmann\napproach for small frequencies, or using Kubo's formula for resonances at\nfinite frequency. However, a precise connection between both approaches has not\nbeen established. Focusing on the second order nonlinear response, here we show\nhow the semiclassical limit can be recovered from perturbation theory in the\nvelocity gauge, provided that finite quasiparticle lifetimes are taken into\naccount. We find that matrix elements related to the band geometry combine in\nthis limit to produce the semiclassical nonlinear conductivity. We demonstrate\nthe power of the new formalism by deriving a quantum contribution to the\nnonlinear conductivity which is of order $\\tau^{-1}$ in the relaxation time\n$\\tau$, which is principally inaccessible within the Boltzmann approach. We\noutline which steps can be generalized to higher orders in the applied\nperturbation, and comment about potential experimental signatures of our\nresults.",
        "positive": "Flexible control of the Peierls transition in metallic C$_{60}$ polymers: The metal-semiconductor transition of peanut-shaped fullerene (C$_{60}$)\npolymers is clarified by considering the electron-phonon coupling in the uneven\nstructure of the polymers. We established a theory that accounts for the\ntransition temperature $T_c$ reported in a recent experiment and also suggests\nthat $T_c$ is considerably lowered by electron doping or prolonged irradiation\nduring synthesis. The decrease in $T_c$ is an appealing phenomenon with regard\nto realizing high-conductivity C$_{60}$-based nanowires even at low\ntemperatures."
    },
    {
        "anchor": "Molecular Dynamics Simulations of Heat Conduction in Nanostructures:\n  Effect of Heat Bath: We investigate systematically the impacts of heat bath used in molecular\ndynamics simulations on heat conduction in nanostructures exemplified by\nSilicon Nanowires (SiNWs) and Silicon/Germanium nano junction. It is found that\nmultiple layers of Nos\\'e-Hoover heat bath are required to reduce the\ntemperature jump at the boundary, while only a single layer of Langevin heat\nbath is sufficient to generate a linear temperature profile with small boundary\ntemperature jump. Moreover, an intermediate value of heat bath parameter is\nrecommended for both Nos\\'e-Hoover and Langevin heat bath in order to achieve\ncorrect temperature profile and thermal conductivity in homogeneous materials.\nFurthermore, the thermal rectification ratio in Si/Ge thermal diode depends on\nthe choice of Nos\\'e-Hoover heat bath parameter remarkably, which may lead to\nnon-physical results. In contrast, Langevin heat bath is recommended because it\ncan produce consistent results with experiment in large heat bath parameter\nrange.",
        "positive": "Double Quantum Dots in Carbon Nanotubes: We study the two-electron eigenspectrum of a carbon-nanotube double quantum\ndot with spin-orbit coupling. Exact calculation are combined with a simple\nmodel to provide an intuitive and accurate description of single-particle and\ninteraction effects. For symmetric dots and weak magnetic fields, the\ntwo-electron ground state is antisymmetric in the spin-valley degree of freedom\nand is not a pure spin-singlet state. When double occupation of one dot is\nfavored by increasing the detuning between the dots, the Coulomb interaction\ncauses strong correlation effects realized by higher orbital-level mixing.\nChanges in the double-dot configuration affect the relative strength of the\nelectron-electron interactions and can lead to different ground state\ntransitions. In particular, they can favor a ferromagnetic ground state both in\nspin and valley degrees of freedom. The strong suppression of the energy gap\ncan cause the disappearance of the Pauli blockade in transport experiments and\nthereby can also limit the stability of spin-qubits in quantum information\nproposals. Our analysis is generalized to an array of coupled dots which is\nexpected to exhibit rich many-body behavior."
    },
    {
        "anchor": "Current-driven magnetization dynamics and their correlation with\n  magnetization configurations in perpendicularly magnetized tunnel junctions: We study spin-transfer-torque driven magnetization dynamics of a\nperpendicular magnetic tunnel junction (MTJ) nanopillar. Based on the\ncombination of spin-torque ferromagnetic resonance and microwave spectroscopy\ntechniques, we demonstrate that the free layer (FL) and the weak pinned\nreference layer (RL) exhibit distinct dynamic behaviors with opposite frequency\nvs. field dispersion relations. The FL can support a single coherent spin-wave\n(SW) mode for both parallel and antiparallel configurations, while the RL\nexhibits spin-wave excitation only for the antiparallel state. These two SW\nmodes corresponding to the FL and RL coexist at an antiparallel state and\nexhibit a crossover phenomenon of oscillation frequency with increasing the\nexternal magnetic field, which could be helpful in the mutual synchronization\nof auto-oscillations for SW-based neuromorphic computing.",
        "positive": "Theory of resonant Raman scattering: Toward a comprehensive \\textit{ab\n  initio} description: We develop a general, fully quantum mechanical theory of Raman scattering\nfrom first principles in terms of many-body correlation functions. In order to\narrive at expressions that are practically useful in the context of condensed\nmatter physics, we adopt the Lehmann-Symanzik-Zimmermann reduction formula from\nhigh-energy physics and formulate in the modern language of many-body\nperturbation theory. This enables us to derive a general and practically useful\nexpression for the Raman scattering rate in terms of quantities that can be\ncomputed \\textit{ab initio}. Our work paves the way toward a comprehensive\ncomputational approach to the calculation of Raman spectra that goes beyond the\ncurrent state of the art by capturing both excitonic and non-adiabatic effects."
    },
    {
        "anchor": "Quantitative signal extraction in the dynamic range of nanomechanical\n  systems by free and constrained fitting: We present a free and a constrained fitting procedure for quantitative signal\nextraction of nanomechanical systems in the dynamic range and for physical\nmodel testing. We demonstrate that applying the free-fitting procedure to the\nmeasured frequency response of silicon nitride (SiN) nanomembranes at varying\npressure enables us to disentangle the intrinsic membrane vibration properties\nfrom the system response, thereby giving quantitative access to the\neigenfrequency, quality factor, coupling strength between resonator and drive\nsystem, and to system noise. The validity of physical models for quantities\nsuch as excitation, fluctuations, and damping mechanisms can be verified by\nimposing additional mathematical links between different physical parameters as\nconstraints in the constrained fitting procedure. We verify the performance of\nthe constrained fitting procedure for the same samples tested in various\nexperimental setups.",
        "positive": "Single-shot read-out of an individual electron spin in a quantum dot: Spin is a fundamental property of all elementary particles. Classically it\ncan be viewed as a tiny magnetic moment, but a measurement of an electron spin\nalong the direction of an external magnetic field can have only two outcomes:\nparallel or anti-parallel to the field. This discreteness reflects the quantum\nmechanical nature of spin. Ensembles of many spins have found diverse\napplications ranging from magnetic resonance imaging to magneto-electronic\ndevices, while individual spins are considered as carriers for quantum\ninformation. Read-out of single spin states has been achieved using optical\ntechniques, and is within reach of magnetic resonance force microscopy.\nHowever, electrical read-out of single spins has so far remained elusive. Here,\nwe demonstrate electrical single-shot measurement of the state of an individual\nelectron spin in a semiconductor quantum dot. We use spin-to-charge conversion\nof a single electron confined in the dot, and detect the single-electron charge\nusing a quantum point contact; the spin measurement visibility is ~65%.\nFurthermore, we observe very long single-spin energy relaxation times (up to\n0.85 ms at a magnetic field of 8 Tesla), which are encouraging for the use of\nelectron spins as carriers of quantum information."
    },
    {
        "anchor": "Oscillating sign of drag in high Landau levels: Motivated by experiments, we study the sign of the Coulomb drag voltage in a\ndouble layer system in a strong magnetic field. We show that the commonly used\nFermi Golden Rule approach implicitly assumes a linear dependence of\nintra-layer conductivity on density, and is thus inadequate in strong magnetic\nfields. Going beyond this approach, we show that the drag voltage commonly\nchanges sign with density difference between the layers. We predict that in the\nQuantum Hall regime the Hall and longitudinal drag resistivities are\ncomparable. Our results are also relevant for pumping and acoustoelectric\nexperiments.",
        "positive": "Determination of the electronic structure of bilayer graphene from\n  infrared spectroscopy results: We present an experimental study of the infrared conductivity, transmission,\nand reflection of a gated bilayer graphene and their theoretical analysis\nwithin the Slonczewski-Weiss-McClure (SWMc) model. The infrared response is\nshown to be governed by the interplay of the interband and the intraband\ntransitions among the four bands of the bilayer. The position of the main\nconductivity peak at the charge neutrality point is determined by the\ninterlayer tunneling frequency. The shift of this peak as a function of the\ngate voltage gives information about less known parameters of the SWMc model,\nin particular, those responsible for the electron-hole and sublattice\nasymmetries. These parameter values are shown to be consistent with recent\nelectronic structure calculations for the bilayer graphene and the SWMc\nparameters commonly used for the bulk graphite."
    },
    {
        "anchor": "Nonlinear dynamics of topological Dirac fermions in 2D spin-orbit\n  coupled materials: The graphene family materials are two-dimensional staggered monolayers with a\ngapped energy band structure due to intrinsic spin-orbit coupling. The mass\ngaps in these materials can be manipulated on-demand via biasing with a static\nelectric field, an off-resonance circularly polarized laser, or an exchange\ninteraction field, allowing the monolayer to be driven through a multitude of\ntopological phase transitions. We investigate the dynamics of spin-orbit\ncoupled graphene family materials to unveil topological phase transition\nfingerprints embedded in the nonlinear regime and show how these signatures\nmanifest in the nonlinear Kerr effect and in third-harmonic generation\nprocesses. We show that the resonant nonlinear spectral response of topological\nfermions can be traced to specific Dirac cones in these materials, enabling\ncharacterization of topological invariants in any phase by detecting the\ncross-polarized component of the electromagnetic field. By shedding light on\nthe unique processes involved in harmonic generation via topological phenomena\nour findings open an encouraging path towards the development of novel\nnonlinear systems based on two-dimensional semiconductors of the graphene\nfamily.",
        "positive": "Characteristics of persistent spin current components in a\n  quasi-periodic Fibonacci ring with spin-orbit interactions: Prediction of\n  spin-orbit coupling and on-site energy: In the present work we investigate the behavior of all three components of\npersistent spin current in a quasi-periodic Fibonacci ring subjected to Rashba\nand Dresselhaus spin-orbit interactions. Analogous to persistent charge current\nin a conducting ring where electrons gain a Berry phase in presence of magnetic\nflux, spin Berry phase is associated during the motion of electrons in presence\nof a spin-orbit field which is responsible for the generation of spin current.\nThe interplay between two spin-orbit fields along with quasi-periodic Fibonacci\nsequence on persistent spin current is described elaborately, and from our\nanalysis, we can estimate the strength of any one of two spin-orbit couplings\ntogether with on-site energy, provided the other is known."
    },
    {
        "anchor": "Electron transport in armchair single-wall carbon nanotubes: The rates of electron scattering via phonons in the armchair single-wall\ncarbon nanotubes were calculated by using the improved scattering theory within\nthe tight-binding approximation. Therefore, the problem connected with the\ndiscrepancy of the scattering rates calculated in the framework of the\nclassical scattering theory and ones predicted by experimental data was\nclarified. Then these results were used for the solving of the kinetic\nBoltzmann equation to describe electron transport properties of the nanotubes.\nThe equation was solved numerically by using both the finite difference\napproach and the Monte Carlo simulation procedure.",
        "positive": "Observing a scale anomaly and a universal quantum phase transition in\n  graphene: One of the most interesting predictions resulting from quantum physics, is\nthe violation of classical symmetries, collectively referred to as anomalies. A\nremarkable class of anomalies occurs when the continuous scale symmetry of a\nscale free quantum system is broken into a discrete scale symmetry for a\ncritical value of a control parameter. This is an example of a (zero\ntemperature) quantum phase transition. Such an anomaly takes place for the\nquantum inverse square potential known to describe 'Efimov physics'. Broken\ncontinuous scale symmetry into discrete scale symmetry also appears for a\ncharged and massless Dirac fermion in an attractive $1/r$ Coulomb potential.\nThe purpose of this article is to demonstrate the universality of this quantum\nphase transition and to present convincing experimental evidence of its\nexistence for a charged and massless fermion in an attractive Coulomb potential\nas realised in graphene."
    },
    {
        "anchor": "Comment on \"Influence of Dzyaloshinskii-Moriya Exchange Interaction on\n  Quantum Phase Interference of Spins\": In a recent Letter [1], Wernsdorfer et al. report an experimental study of a\nMn12 molecular wheel which shows essentially identical behavior to the Mn12\nwheel studied by Ramsey et al. [2]. In their Letter, Wernsdorfer et al. use the\nsame model of a dimer of two exchange-coupled spins used in [2] as a basis to\nextend the study of the influence of the Dzyaloshinskii-Moriya (DM) interaction\non the quantum tunneling of the magnetization of this system; in particular,\nthey show that a tilt of the DM vector away from the uniaxial anisotropy axis\ncan account for the asymmetric nature of the quantum interference minima\nassociated with resonances between states of opposite parity, e.g., k = 1(A).\nWe want to stress that the inclusion of DM interactions in a system with\ninversion symmetry cannot mix states of opposite parity; i.e., the parity\noperator commutes with the Hamiltonian. Consequently, the use by Wernsdorfer et\nal. of a single DM vector in a centrosymmetric dimer is strictly forbidden\nsince it implicitly violates parity conservation. The authors correctly point\nout that the lack of an inversion center between each pair of manganese ions on\nthe wheel justifies the possibility of local DM interactions, even though the\ncomplete molecule has an inversion center. However, these local DM interactions\nmust also satisfy the molecular inversion symmetry; i.e., they cannot mix\nstates of opposite parity.We agree that such DM interactions are not always\ncompletely innocuous; e.g., they can mix spin states having the same parity.\nIndeed, in kagome systems [3] (cited in [1]), this can lead to weak\nferromagnetism. Nevertheless, the inversion symmetry of the lattice is\npreserved and parity is still conserved.",
        "positive": "Electroluminescence in Single Layer MoS2: We detect electroluminescence in single layer molybdenum disulphide (MoS2)\nfield-effect transistors built on transparent glass substrates. By comparing\nabsorption, photoluminescence, and electroluminescence of the same MoS2 layer,\nwe find that they all involve the same excited state at 1.8eV. The\nelectroluminescence has pronounced threshold behavior and is localized at the\ncontacts. The results show that single layer MoS2, a direct band gap\nsemiconductor, is promising for novel optoelectronic devices, such as\n2-dimensional light detectors and emitters."
    },
    {
        "anchor": "Phonon-assisted carrier cooling in h-BN/graphene van der Waals\n  heterostructures: Being used in optoelectronic devices as ultra-thin conductor-insulator\njunctions, detailed investigations are needed about how exactly h-BN and\ngraphene hybridize. Here, we present a comprehensive ab initio study of hot\ncarrier dynamics governed by electron-phonon scattering at the h-BN/graphene\ninterface, using graphite (bulk), monolayer and bilayer graphene as benchmark\nmaterials. In contrast to monolayer graphene, all multilayer structures possess\nlow-energy optical phonon modes that facilitate carrier thermalization. We find\nthat the h-BN/graphene interface represents an exception with comparatively\nweak coupling between low-energy optical phonons and electrons. As a\nconsequence, the thermalization bottleneck effect, known from graphene,\nsurvives hybridization with h-BN but is substantially reduced in all other\nbilayer and multilayer cases considered. In addition, we show that the quantum\nconfinement in bilayer graphene does not have a significant influence on the\nthermalization time compared to graphite and that bilayer graphene can hence\nserve as a minimal model for the bulk counterpart.",
        "positive": "A spin-rotation mechanism of Einstein-de Haas effect based on a\n  ferromagnetic disk: Spin-rotation coupling (SRC) is a fundamental phenomenon that connects\nelectronic spins with the rotational motion of a medium. We elucidate the\nEinstein-de Haas (EdH) effect and its inverse with SRC as the microscopic\nmechanism using the dynamic spin-lattice equations derived by elasticity theory\nand Lagrangian formalism. By applying the coupling equations to an iron disk in\na magnetic field, we exhibit the transfer of angular momentum and energy\nbetween spins and lattice, with or without damping. The timescale of the\nangular momentum transfer from spins to the entire lattice is estimated by our\ntheory to be on the order of 0.01 ns, for the disk with a radius of 100 nm.\nMoreover, we discover a linear relationship between the magnetic field strength\nand the rotation frequency, which is also enhanced by a higher ratio of Young's\nmodulus to Poisson's coefficient. In the presence of damping, we notice that\nthe spin-lattice relaxation time is nearly inversely proportional to the\nmagnetic field. Our explorations will contribute to a better understanding of\nthe EdH effect and provide valuable insights for magneto-mechanical\nmanufacturing."
    },
    {
        "anchor": "One-step multi-qubit GHZ state generation in a circuit QED system: We propose a one-step scheme to generate GHZ states for superconducting flux\nqubits or charge qubits in a circuit QED setup. The GHZ state can be produced\nwithin the coherence time of the multi-qubit system. Our scheme is independent\nof the initial state of the transmission line resonator and works in the\npresence of higher harmonic modes. Our analysis also shows that the scheme is\nrobust to various operation errors and environmental noise.",
        "positive": "Spatial structure of an incompressible Quantum Hall strip: The incompressible Quantum Hall strip is sensitive to charging of localized\nstates in the cyclotron gap. We study the effect of localized states by a\ndensity functional approach and find electron density and the strip width as a\nfunction of the density of states in the gap. Another important effect is\nelectron exchange. By using a model density functional which accounts for\nnegative compressibility of the QH state, we find electron density around the\nstrip. At large exchange, the density profile becomes nonmonotonic, indicating\nformation of a 1D Wigner crystal at the strip edge. Both effects, localized\nstates and exchange, lead to a substantial increase of the strip width."
    },
    {
        "anchor": "Second harmonic generation in graphene dressed by a strong terahertz\n  field: We observe enhanced second-harmonic generation in monolayer graphene in the\npresence of an ultra-strong terahertz field pulse with a peak amplitude of 250\nkV/cm. This is a strongly nonperturbative regime of light-matter interaction in\nwhich particles get accelerated to energies exceeding the initial Fermi energy\nof 0.2 eV over a timescale of a few femtoseconds. The second-harmonic current\nis generated as electrons drift through the region of momenta corresponding to\ninterband transition resonance at an optical frequency. The resulting strongly\nasymmetric distortion of carrier distribution in momentum space gives rise to\nan enhanced electric-dipole nonlinear response at the second harmonic. We\ndevelop an approximate analytic theory of this effect which accurately predicts\nobserved intensity and polarization of the second-harmonic signal.",
        "positive": "Intrinsic properties of suspended MoS2 on SiO2/Si pillar arrays for\n  nanomechanics and optics: Semiconducting 2D materials, such as transition metal dichalcogenides (TMDs),\nare emerging in nanomechanics, optoelectronics, and thermal transport. In each\nof these fields, perfect control over 2D material properties including strain,\ndoping, and heating is necessary, especially on the nanoscale. Here, we study\nclean devices consisting of membranes of single-layer MoS2 suspended on pillar\narrays. Using Raman and photoluminescence spectroscopy, we have been able to\nextract, separate and simulate the different contributions on the nanoscale and\nto correlate these to the pillar array design. This control has been used to\ndesign a periodic MoS2 mechanical membrane with a high reproducibility and to\nperform optomechanical measurements on arrays of similar resonators with a\nhigh-quality factor of 600 at ambient temperature, hence opening the way to\nmulti-resonator applications with 2D materials. At the same time, this study\nconstitutes a reference for the future development of well-controlled optical\nemissions within 2D materials on periodic arrays with reproducible behavior. We\nmeasured a strong reduction of the MoS2 band-gap induced by the strain\ngenerated from the pillars. A transition from direct to indirect band gap was\nobserved in isolated tent structures made of MoS2 and pinched by a pillar. In\nfully suspended devices, simulations were performed allowing both the\nextraction of the thermal conductance and doping of the layer. Using the\ncorrelation between the influences of strain and doping on the MoS2 Raman\nspectrum, we have developed a simple, elegant method to extract the local\nstrain in suspended and non-suspended parts of a membrane. This opens the way\nto experimenting with tunable coupling between light emission and vibration."
    },
    {
        "anchor": "A generalized enhanced Fourier law and underlying connections to major\n  frameworks for quasi-ballistic phonon transport: An enhanced Fourier law (EFL) that accounts for quasi-ballistic phonon\ntransport effects in a formulation entirely in terms of physical observables,\nis derived from the Boltzmann transport equation, assuming a gray population of\nquasi-ballistic phonon modes. This equation is generalized to an arbitrary\nphonon population. Other phonon transport models are analyzed in the context of\nthe generalized EFL and connections are made between the generalized EFL and\nother models, revealing the essential unity of seemingly disparate models\nreported in the literature.",
        "positive": "Time-Reversal Even Charge Hall Effect from Twisted Interface Coupling: Under time-reversal symmetry, a linear charge Hall response is usually deemed\nto be forbidden by the Onsager relation. In this work, we discover a scenario\nfor realizing a time-reversal even linear charge Hall effect in a non-isolated\ntwo-dimensional crystal allowed by time reversal symmetry. The restriction by\nOnsager relation is lifted by interfacial coupling with an adjacent layer,\nwhere the overall chiral symmetry requirement is fulfilled by a twisted\nstacking. We reveal the underlying band geometric quantity as the\nmomentum-space vorticity of layer current. The effect is demonstrated in\ntwisted bilayer graphene and twisted homobilayer transition metal\ndichalcogenides with a wide range of twist angles, which exhibit giant Hall\nratios under experimentally practical conditions, with gate voltage controlled\non-off switch. This work reveals intriguing Hall physics in chiral structures,\nand opens up a research direction of layertronics that exploits the quantum\nnature of layer degree of freedom to uncover exciting effects."
    },
    {
        "anchor": "A simple variational quantum Monte Carlo-effective mass approach for\n  excitons and trions in quantum dots: A computational model is presented to calculate the ground state energy of\nneutral and charged excitons confined in semiconductor quantum dots. The model\nis based on the variational Quantum Monte Carlo method and effective mass\nHamiltonians. Through an iterative Newton-Rhapson process, minimizing the local\nenergy, and (optional) parallelization of random walkers, fast and accurate\nestimates of both confinement and Coulomb binding energies can be obtained in\nstandard desktop computers.\n  To illustrate the reach of the model, we provide Fortran programs and\nillustrative calculations for colloidal CdSe nanoplatelets with large lateral\ndimensions and dielectric confinement, where electronic correlations are\nstrong. The results compare well with exact variational calculations and\nlargely outperform configuration interaction calculations in computational\nefficiency.",
        "positive": "Dual topological nodal line and nonsymmorphic Dirac semimetal in three\n  dimensions: Previously known three-dimensional Dirac semimetals (DSs) occur in two types\n-- topological DSs and nonsymmorphic DSs. Here we present a novel\nthree-dimensional DS that exhibits both features of the topological and\nnonsymmorphic DSs. We introduce a minimal tight-binding model for the space\ngroup 100 that describes a layered crystal made of two-dimensional planes in\nthe $p4g$ wallpaper group. Using this model, we demonstrate that double\nglide-mirrors allow a noncentrosymmetric three-dimensional DS that hosts both\nsymmetry-enforced Dirac points at time-reversal invariant momenta and\ntwofold-degenerate Weyl nodal lines on a glide-mirror-invariant plane in\nmomentum space. The proposed DS allows for rich topological physics manifested\nin both topological surface states and topological phase diagrams, which we\ndiscuss in detail. We also perform first-principles calculations to predict\nthat the proposed DS is realized in a set of existing materials BaLa$X$B$Y_5$,\nwhere $X$ = Cu or Au, and $Y$ = O, S, or Se."
    },
    {
        "anchor": "Casimir energy for acoustic phonons in graphene: We find the Casimir energy, at finite temperature, for acoustic phonons in a\nGraphene sheet suspended over a rectangular trench, and the corresponding\nCasimir forces are interpreted as correction terms to the built-in tensions of\nthe Graphene. We show that these corrections generally break the tensional\nisotropy of the membrane, and can increase or decrease the membrane tension. We\ndemonstrate that for a narrow rectangular trench with side-lengths in the order\nof few nanometers and few micrometers, these temperature corrections are\nexpected to be noticeable ($\\sim 10^{-4} N/m$) at the room temperature. These\ncorrections would be even more considerable by increasing the temperature, and\ncan be applied for adjusting the built-in tension of the Graphene. Consequently\nwe introduce a corrected version for the fundamental resonance frequency of the\nGraphene resonator.",
        "positive": "Magnetic field dependence of electronic properties of MoS$_2$ quantum\n  dots with different edges: Using the tight-binding approach, we investigate the energy spectrum of\nsquare, triangular and hexagonal MoS$_2$ quantum dots (QDs) in the presence of\na perpendicular magnetic field. Novel edge states emerge in MoS$_2$ QDs, which\nare distributed over the whole edge which we call ring states. The ring states\nare robust in the presence of spin-orbit coupling (SOC). The corresponding\nenergy levels of the ring states oscillate as function of the perpendicular\nmagnetic field which are related to Aharonov-Bohm oscillations. Oscillations in\nthe magnetic field dependence of the energy levels and the peaks in the\nmagneto-optical spectrum emerge (disappear) as the ring states are formed\n(collapsed). The period and the amplitude of the oscillation decreases with the\nsize of the MoS$_2$ QDs."
    },
    {
        "anchor": "Dynamic phase diagram of dc-pumped magnon condensates: We study the effects of nonlinear dynamics and damping by phonons on a system\nof interacting electronically pumped magnons in a ferromagnet. The nonlinear\neffects are crucial for constructing the dynamic phase diagram, which describes\nhow \"swasing\" and Bose-Einstein condensation emerge out of the\nquasiequilibrated thermal cloud of magnons. We analyze the system in the\npresence of magnon damping and interactions, demonstrating the continuous onset\nof stable condensates as well as hysteretic transitions.",
        "positive": "A new transport phenomenon in nanostructures: A mesoscopic analog of the\n  Braess paradox encountered in road networks: The Braess paradox, known for traffic and other classical networks, lies in\nthe fact that adding a new route to a congested network in an attempt to\nrelieve congestion can counter-intuitively degrade the overall network\nperformance. Recently, we have extended the concept of Braess paradox to\nsemiconductor mesoscopic networks, whose transport properties are governed by\nquantum physics. In this paper, we demonstrate theoretically that, alike in\nclassical systems, congestion plays a key role in the occurrence of a Braess\nparadox in mesoscopic networks."
    },
    {
        "anchor": "Photo-Induced Image Current: We study the possibility of the generation of the photo-induced image\ncurrents at a distance from the surface of nano-sized metal clusters by using\ntime-dependent perturbation theory. We reveal that the wave function of an\nelectron excited to the image state is localized outside the surface and\ncurrent flows in a spherical shell whose radius is a few times the radius of\nthe sphere. Spin polarized light has been applied to a perfect icosahedral\nmetal cluster Li$_{13}$ whose optimization is achieved by molecular dynamic\nsimulation and band structure is obtained by DFT method and by solution of\nradial Schr\\\"odinger equation. Up to our knowledge, despite the great effort on\ntheir characteristics, image electrons have not been the subject of the studies\non photo-induced current.",
        "positive": "Liquid-induced damping of mechanical feedback effects in single electron\n  tunneling through a suspended carbon nanotube: In single electron tunneling through clean, suspended carbon nanotube devices\nat low temperature, distinct switching phenomena have regularly been observed.\nThese can be explained via strong interaction of single electron tunneling and\nvibrational motion of the nanotube. We present measurements on a highly stable\nnanotube device, subsequently recorded in the vacuum chamber of a dilution\nrefrigerator and immersed in the 3He/4He mixture of a second dilution\nrefrigerator. The switching phenomena are absent when the sample is kept in the\nviscous liquid, additionally supporting the interpretation of dc-driven\nvibration. Transport measurements in liquid helium can thus be used for finite\nbias spectroscopy where otherwise the mechanical effects would dominate the\ncurrent."
    },
    {
        "anchor": "Fine structure and magneto-optics of exciton, trion, and charged\n  biexciton states in single InAs quantum dots emitting at 1.3 um: We present a detailed investigation into the optical characteristics of\nindividual InAs quantum dots (QDs) grown by metalorganic chemical vapor\ndeposition, with low temperature emission in the telecoms window around 1300\nnm. Using micro-photoluminescence (PL) spectroscopy we have identified neutral,\npositively charged, and negatively charged exciton and biexciton states.\nTemperature-dependent measurements reveal dot-charging effects due to\ndifferences in carrier diffusivity. We observe a pronounced linearly polarized\nsplitting of the neutral exciton and biexciton lines (~250 ueV) resulting from\nasymmetry in the QD structure. This asymmetry also causes a mixing of the\nexcited trion states which is manifested in the fine structure and polarization\nof the charged biexciton emission; from this data we obtain values for the\nratio between the anisotropic and isotropic electron-hole exchange energies of\n(Delta1)/(Delta0)= 0.2--0.5. Magneto-PL spectroscopy has been used to\ninvestigate the diamagnetic response and Zeeman splitting of the various\nexciton complexes. We find a significant variation in g-factor between the\nexciton, the positive biexciton, and the negative biexciton; this is also\nattributed to anisotropy effects and the difference in lateral extent of the\nelectron and hole wavefunctions.",
        "positive": "Surface-enhanced Raman scattering in graphene deposited on\n  Al$_x$Ga$_{1-x}$N/GaN axial heterostructure nanowires: The surface-enhanced Raman scattering in graphene deposited on AlxGa1-xN/GaN\naxial heterostructure nanowires was investigated. The intensity of graphene\nRaman spectra was found not to be correlated with aluminium content. Analysis\nof graphene Raman bands parameters, KPFM and electroreflectance showed a\nscreening of polarization charges. Theoretical calculations showed that plasmon\nresonance in graphene is far beyond the Raman spectral range. This excludes the\npresence of an electromagnetic mechanism of SERS and therefore suggests the\nchemical mechanism of enhancement."
    },
    {
        "anchor": "Photogalvanic response in multi-Weyl semimetals: We investigate the dependence of the photogalvanic response of a multi-Weyl\nsemimetal on its topological charge, tilt, and chemical potential. We derive\nanalytical expressions for the shift and injection conductivities for tilted\ncharge-$n$ Weyl points $(n=1,2,3)$ using a low energy two-band effective\nHamiltonian. For double-Weyl semimetals, we also compute the response from\ntwo-band and four-band tight-binding models with broken time-reversal symmetry\nto study the effect of band bending and the contributions from higher bands. We\nfind a significant deviation in the responses obtained from the effective\nlow-energy continuum model and more realistic four-band continuum and\ntight-binding models. We analyze several different limits of these models. We\ndescribe the nature of the deviations and provide estimates of their dependence\non the frequency and other model parameters. Our analysis provides a simple\nexplanation for the first-principle calculation based frequency dependence of\nthe injection current in SrSi$_2$. Additionally, we find interesting parameter\nregimes where the frequency dependence of the non-linear optical response can\nbe directly used to probe the type-I/type-II nature of the Weyl cone. We obtain\nanalytical results for the charge-4 Weyl semimetal by reducing the original\nproblem involving a triple $k$-space integral to one with only a double\nintegral. This simplification allows us to extract all relevant information\nabout the nature of its second-order dc response and the precise condition for\nobserving circular photogalvanic effect quantization. The semi-analytical\napproach presented here can also be extended to a systematic study of second\nharmonic generation and first-order optical conductivity in charge-4 Weyl\nsemimetals.",
        "positive": "Conductance Anomaly and Fano Factor Reduction in Quantum Point Contacts: We report an experimental study on the shot noise as well as the dc transport\nproperties of a quantum point contact (QPC) whose conductance anomaly can be\ntuned electrostatically by the gate electrodes. By controlling the single QPC\nso that it has no anomaly or an anomaly at $0.5 G_0$, $0.8 G_0$ or $0.9 G_0$\n($G_0 = 2e^2/h$), we prove that the anomaly always accompanies the Fano factor\nreduction due to the asymmetric transmission of the two spin-dependent channels\nfor the conductance lower than $G_0$. For the QPC tuned to have the anomaly at\n$0.5 G_0$ the channel asymmetry is found to be as large as 67% with the spin\ngap energy gradually evolving as the conductance increases."
    },
    {
        "anchor": "Interlayer Transport in Bilayer Quantum Hall Systems: Bilayer quantum Hall systems have a broken symmetry ground state at filling\nfactor $\\nu=1$ which can be viewed either as an excitonic superfluid or as a\npseudospin ferromagnet. We present a theory of inter-layer transport in quantum\nHall bilayers that highlights remarkable similarities and critical differences\nbetween transport in Josephson junction and ferromagnetic metal spin-transfer\ndevices. Our theory is able to explain the size of the large but finite low\nbias interlayer conductance and the voltage width of this collective transport\nanomaly.",
        "positive": "Fermi-arc diversity on surface terminations of the magnetic Weyl\n  semimetal Co3Sn2S2: Bulk-surface correspondence in Weyl semimetals assures the formation of\ntopological \"Fermi-arc\" surface bands whose existence is guaranteed by bulk\nWeyl nodes. By investigating three distinct surface terminations of the\nferromagnetic semimetal Co3Sn2S2 we verify spectroscopically its classification\nas a time reversal symmetry broken Weyl semimetal. We show that the distinct\nsurface potentials imposed by three different terminations modify the Fermi-arc\ncontour and Weyl node connectivity. On the Sn surface we identify\nintra-Brillouin zone Weyl node connectivity of Fermi-arcs, while on Co\ntermination the connectivity is across adjacent Brillouin zones. On the S\nsurface Fermi-arcs overlap with non-topological bulk and surface states that\nambiguate their connectivity and obscure their exact identification. By these\nwe resolve the topologically protected electronic properties of a Weyl\nsemimetal and its unprotected ones that can be manipulated and engineered."
    },
    {
        "anchor": "Charge and spin manipulation in a few-electron double dot: We demonstrate high speed manipulation of a few-electron double quantum dot.\nIn the one-electron regime, the double dot forms a charge qubit. Microwaves are\nused drive transitions between the (1,0) and (0,1) charge states of the double\ndot. A local quantum point contact charge detector measures the photon-induced\nchange in occupancy of the charge states. Charge detection is used to measure\nT1~16 ns and also provides a lower bound estimate for T2* of 400 ps for the\ncharge qubit. In the two-electron regime we use pulsed-gate techniques to\nmeasure the singlet-triplet relaxation time for nearly-degenerate spin states.\nThese experiments demonstrate that the hyperfine interaction leads to fast spin\nrelaxation at low magnetic fields. Finally, we discuss how two-electron spin\nstates can be used to form a logical spin qubit.",
        "positive": "A scattering matrix formulation of the topological index of interacting\n  fermions in one-dimensional superconductors: We construct a scattering matrix formulation for the topological\nclassification of one-dimensional superconductors with effective time reversal\nsymmetry in the presence of interactions. For a closed geometry, Fidkowski and\nKitaev have shown that such systems have a $\\mathbb{Z}_8$ topological\nclassification. We show that in the weak coupling limit, these systems retain a\nunitary scattering matrix at zero temperature, with a topological index given\nby the trace of the Andreev reflection matrix, $\\mbox{tr}\\, r_{\\rm he}$. With\ninteractions, $\\mbox{tr}\\, r_{\\rm he}$ generically takes on the finite set of\nvalues $0$, $\\pm 1$, $\\pm 2$, $\\pm 3$, and $\\pm 4$. We show that the two\ntopologically equivalent phases with $\\mbox{tr}\\, r_{\\rm he} = \\pm 4$ support\nemergent many-body end states, which we identify to be a topologically\nprotected Kondo-like resonance. The path in phase space that connects these\nequivalent phases crosses a non-fermi liquid fixed point where a multiple\nchannel Kondo effect develops. Our results connect the topological index to\ntransport properties, thereby highlighting the experimental signatures of\ninteracting topological phases in one dimension."
    },
    {
        "anchor": "Spin-current rectification through a quantum dot using temperature bias: We analyze spin-dependent transport through a spin-diode in the presence of\nspin-flip and under influence of temperature bias. The current polarization and\nthe spin accumulation are investigated in detail by means of reduced density\nmatrix. Results show that the spin accumulation is linearly increased when the\nmetallic electrode is warmer whereas, its behavior is more complicated when the\nferromagnetic lead is warmer. Furthermore, spin-flip causes that the current\npolarization becomes not only a function of spin-flip rate but also a function\nof temperature. The current polarization is reduced up to 90% if the time of\nspin-flip is equal to the tunneling time. The behavior of spin-dependent\ncurrent is also studied as a function of temperature, spin-flip rate, and\npolarization.",
        "positive": "Spin-polarized Andreev tunneling through the Rashba chain: We demonstrate that the selective equal spin Andreev reflection (SESAR)\nspectroscopy can be used in STM experiments to distinguish the zero-energy\nMajorana quasiparticles from the ordinary fermionic states of the Rashba chain.\nSuch technique, designed for probing the p-wave superconductivity, could be\napplied to the intersite pairing of equal-spin electrons in the chain of\nmagnetic Fe atoms deposited on the superconducting Pb substrate. Our\ncalculations of the effective pairing amplitude for individual spin components\nimply the magnetically polarized Andreev conductance, which can be used to\n`filter' the Majorana quasiparticles from the ordinary in-gap states, although\nthe pure spin current (i.e., perfect polarization) is impossible."
    },
    {
        "anchor": "Tunable Magnonic Frequency and Damping in [Co/Pd]8 Multilayers with\n  Variable Co Layer Thickness: We report the experimental observation of collective picosecond magnetization\ndynamics in [Co/Pd]8 multilayers with perpendicular magnetic anisotropy. The\nprecession frequency shows large and systematic variation from about 5 GHz to\nabout 90 GHz with the decrease in the Co layer thickness from 1.0 nm to 0.22 nm\ndue to the linear increase in the perpendicular magnetic anisotropy. The\ndamping coefficient 'alpha' is found to be inversely proportional to the Co\nlayer thickness and a linear relation between the perpendicular magnetic\nanisotropy and 'alpha' is established. We discuss the possible reasons behind\nthe enhanced damping as the d-d hybridization at the interface and spin\npumping. These observations are significant for the applications of these\nmaterials in spintronics and magnonic crystals.",
        "positive": "Temperature dependence of the energy barrier and switching field of\n  magnetic islands with perpendicular anisotropy: Using the highly sensitive anomalous Hall effect (AHE) we have been able to\nmeasure the reversal of a single magnetic island, of diameter 220nm, in an\narray consisting of more than 80 of those islands. By repeatedly traversing the\nhysteresis loop, we measured the thermally actuated fluctuation of the\nswitching field of the islands at the lower and higher ends of the switching\nfield distribution. Based on a novel easy-to-use model, we determined the\nswitching field in the absence of thermal activation, and the energy barrier in\nthe absence of an external field from these fluctuations. By measuring the\nreversal of individual dots in the array as a function of temperature, we\nextrapolated the switching field and energy barrier down to 0K. The\nextrapolated values are not identical to those obtained from the fluctation of\nthe switching field at room temperature, because the properties of the magnetic\nmaterial are temperature dependent. As a result, extrapolating from temperature\ndependent measurements overestimates the energy barrier by more than a factor\nof two. To determine fundamental parameters of the energy barrier between\nmagnetisation states, measuring the fluctuation of the reversal field at the\ntemperature of application is therefore to be preferred. This is of primary\nimportance to applications in data storagea and magnetic logic. For instance in\nfast switching, where the switching field in the absence of thermal activation\nplays a major role, or in long term data stability, which is determined by the\nenergy barrier in the absence of an external field."
    },
    {
        "anchor": "Slider Thickness Promotes Lubricity: from 2D Islands to 3D Clusters: The sliding of three-dimensional clusters and two-dimensional islands\nadsorbed on crystal surfaces represent an important test case to understand\nfriction. Even for the same material, monoatomic islands and thick clusters\nwill not as a rule exhibit the same friction, but specific differences have not\nbeen explored. Through realistic molecular dynamics simulations of the static\nfriction gold on graphite, an experimentally relevant system, we uncover as a\nfunction of gold thickness a progressive drop of static friction from monolayer\nislands, that are easily pinned, towards clusters, that slide more readily. The\nmain ingredient contributing to this thickness-induced lubricity appears to be\nthe increased effective rigidity of the atomic contact, acting to reduce the\ncluster interdigitation with the substrate. A second element which plays a role\nis lateral contact size, which can accommodate the solitons typical of the\nincommensurate interface only above a critical contact diameter, which is\nlarger for monolayer islands than for thick clusters. The two effects concur to\nmake clusters more lubric than islands, and large sizes more lubric than\nsmaller ones. These conclusions are expected to be of broader applicability in\ndiverse nanotribological systems, where the role played by static, and dynamic,\nfriction is generally quite important.",
        "positive": "Kondo resonant spectra in coupled quantum dots: The Kondo effect in coupled quantum dots is investigated from the viewpoint\nof transmission spectroscopy using the slave-boson formalism of the Anderson\nmodel. The antiferromagnetic spin-spin coupling $J$ between the dots is taken\ninto account. Conductance $G$ through the dots connected in a series is\ncharacterized by the competition between the dot-dot tunneling coupling $V_{C}$\nand the level broadening $\\Delta$ in the dots (dot-lead coupling). When\n$V_{C}/\\Delta < 1$, the Kondo resonance is formed between each dot and lead,\nwhich is replaced by a spin-singlet state in the dots at low gate voltages. The\ngate voltage dependence of $G$ has a sharp peak of $2 e^2/h$ in height in the\ncrossover region between the Kondo and spin-singlet states. The sharp peak of\n$G$ survives when the energy levels are different between the dots. When $V_{C}\n/ \\Delta > 1$, the \"molecular levels\" between the Kondo resonant states appear;\nthe Kondo resonant peaks are located below and above the Fermi level in the\nleads at low gate voltages. The gate voltage dependence of $G$ has a broad\npeak, which is robust against $J$. The broad peak splits into two peaks when\nthe energy levels are different, reflecting the formation of the asymmetric\nmolecular levels between the Kondo resonant states."
    },
    {
        "anchor": "Determination of the thickness and orientation of few-layer tungsten\n  ditelluride using polarized Raman spectroscopy: Orthorhombic tungsten ditelluride (WTe2), with a distorted 1T structure,\nexhibits a large magnetoresistance that depends on the orientation, and its\nelectrical characteristics changes rom semimetallic to insulating as the\nthickness decreases. Through polarized Raman spectroscopy in combination with\ntransmission electron diffraction, we establish a reliable method to determine\nthe thickness and crystallographic orientation of few-layer WTe2. The Raman\nspectrum shows a pronounced dependence on the polarization of the excitation\nlaser. We found that the separation between two Raman peaks at ~90 cm-1 and at\n80-86 cm-1, depending on thickness, is a reliable fingerprint for determination\nof the thickness. For determination of the crystallographic orientation, the\npolarization dependence of the A1 modes, measured with the 632.8-nm excitation,\nturns out to be the most reliable. We also discovered that the polarization\nbehaviors of some of the Raman peaks depend on the excitation wavelength as\nwell as thickness, indicating a close interplay between the band structure and\nanisotropic Raman scattering cross section.",
        "positive": "Local density of states above a disk -- geometrical vs. thermal boundary\n  conditions: We analytically calculate the contribution to the local density of states due\nto thermal sources in a disk-like patch within the framework of fluctuational\nelectrodynamics. We further introduce a wavevector cutoff method to approximate\nthis contribution. We compare the results obtained with the source and cutoff\nmethod with the numerical exact LDOS above a metal disk attained by SCUFF-EM\ncalculations. By this comparison we highlight the difference and resemblance of\nthermal and geometrical boundary conditions which are both relevant for\nnear-field scanning microscope measurements. Finally, we give an outlook to\ngeneral lateral temperature profiles and compare it with surface profiles."
    },
    {
        "anchor": "Josephson physics mediated by the Mott insulating phase: We investigate the static and dynamic properties of bosonic lattice systems\nin which condensed and Mott insulating phases co-exist due to the presence of a\nspatially-varying potential. We formulate a description of these inhomogeneous\nsystems and calculate the bulk energy at and near equilibrium. We derive the\nexplicit form of the Josephson coupling between disjoint superfluid regions\nseparated by Mott insulating regions. We obtain detailed estimates for the\nexperimentally-realized case of alternating superfluid and Mott insulating\nspherical shells in a radially symmetric parabolically-confined cold atom\nsystem.",
        "positive": "Bias-Voltage-Induced Topological Phase Transition in Finite Size Quantum\n  Spin Hall Systems in the Presence of a Transverse Electric Field: Using the tight-binding BHZ model and Landauer-B\\\"uttiker formalism, the\ntopological invariant of the finite width of ribbons of HgTe/CdTe quantum well\nis studied in the absence and presence of an external transverse electric\nfield. It will be recognized that a critical current changes topological\ninvariant of ribbons of quantum well. This topological phase transition, which\noccurred by adjustment of the bias voltage, depends on the width of the sample\nand the gate voltage. The profound effects of an external transverse electric\nfield are considered to the separation of spin-up and spin-down band\nstructures, decreasing band gap and tuning the topological phase transition\nbetween ordinary and quantum spin Hall regime. These declares the transverse\nelectric field amplifies the quantum spin Hall regime and causes inducing the\ntopological phase transition in ribbons of quantum well. Our finding may\ninstantly clear some practical aspects of the study in the field of spintronic\nfor employment in spin-based devices."
    },
    {
        "anchor": "Spectrum structure for a three-dimensional periodic array of quantum\n  dots in a uniform magnetic field: By means of the operator extension theory, we construct an explicitly\nsolvable model of a simple-cubic three-dimensional regimented array of quantum\ndots in the presence of a uniform magnetic field. The spectral properties of\nthe model are studied. It is proved that for each magnetic flux the band is the\nimage of the spectrum of the tight-binding operator under an analytical\ntransformation. In the case of rational magnetic flux the spectrum is described\nanalytically. The flux-energy and angle-energy diagrams are obtained\nnumerically.",
        "positive": "X-ray total scattering study of regular and magic-size nanoclusters of\n  cadmium sulphide: Four kinds of magic-size CdS clusters and two different regular CdS quantum\ndots have been studied by x-ray total scattering technique and pair\ndistribution function method. Results for the regular CdS quantum dots could be\nmodelled as a mixed phase of atomic structures based on the two bulk\ncrystalline phases, which is interpreted as representing the effects of\nstacking disorder. However, the results for the magic-size clusters were\nsignificantly different. On one hand, the short-range features in the pair\ndistribution function reflect the bulk, indicating that these structures are\nbased on the same tetrahedral coordination found in the bulk phases (and\ntherefore excluding new types of structures such as cage-like arrangements of\natoms). But on the other hand, the longer- range atomic structure clearly does\nnot reflect the layer structures found in the bulk and the regular quantum\ndots. We compare the effects of two ligands, phenylacetic acid and oleic acid,\nshowing that in two cases the ligand has little effect on the atomic structure\nof the magic-size nanocluster and in another it has a significant effect."
    },
    {
        "anchor": "Electron-phonon cooling power in Anderson insulators: First microscopic theory for electron-phonon energy exchange in Anderson\ninsulators is developed. The major contribution to the cooling power as a\nfunction of electron temperature is shown to be directly related to the\ncorrelation function of the local density of electron states at small energy\ndifference argument. In Anderson insulators not far from localization\ntransition, this correlation function is strongly enhanced by wave-function's\nmulti-fractality and, additionally, by the presence of Mott's resonant pairs of\nlocalized states. The theory we develop explains huge enhancement of the\ncooling power observed in insulating Indium Oxide films as compared to\npredictions of the theory previously developed for disordered metals. Our\nresults open the way to predict the conditions appropriate for the observation\nof Many Body Localization transition those presence in electronic insulators\nwas advocated in the seminal paper by Basko, Aleiner and Altshuler (2006) but\nhave not been convincingly demonstrated yet.",
        "positive": "From Luttinger liquid to non-Abelian quantum Hall states: We formulate a theory of non-Abelian fractional quantum Hall states by\nconsidering an anisotropic system consisting of coupled, interacting one\ndimensional wires. We show that Abelian bosonization provides a simple\nframework for characterizing the Moore Read state, as well as the more general\nRead Rezayi sequence. This coupled wire construction provides a solvable\nHamiltonian formulated in terms of electronic degrees of freedom, and provides\na direct route to characterizing the quasiparticles and edge states in terms of\nconformal field theory. This construction leads to a simple interpretation of\nthe coset construction of conformal field theory, which is a powerful method\nfor describing non Abelian states. In the present context, the coset\nconstruction arises when the original chiral modes are fractionalized into\ncoset sectors, and the different sectors acquire energy gaps due to coupling in\n\"different directions\". The coupled wire construction can also can be used to\ndescribe anisotropic lattice systems, and provides a starting point for models\nof fractional and non-Abelian Chern insulators. This paper also includes an\nextended introduction to the coupled wire construction for Abelian quantum Hall\nstates, which was introduced earlier."
    },
    {
        "anchor": "Quantum-Statistical Current Correlations in Multi-Lead Chaotic Cavities: Quantum mechanics requires that identical particles are treated as\nindistinguishable. This requirement leads to correlations in the fluctuating\nproperties of a system. Theoretical predictions are made for an experiment on a\nmulti-lead chaotic quantum dot which can identify exchange effects in\nelectronic current-current correlations. Interestingly, we find that the\nensemble averaged exchange effects are of the order of the channel number, and\nare insensitive to dephasing.",
        "positive": "(De)confinement of supercurrent in Z_2 Topological Insulators: It is shown that the electric supercurrent flows in a Z_2 topological\ninsulator with U_em(1) X U_z(1) (electromagnetic and spin) gauge symmetries.\nWhen U_z(1) is broken, a dissipationless electric current is still possible to\nflow locally but net charge transfer is absent, i.e., current is confined. In\nthe Kane-Mele model for graphene, this confining-deconfining (superconducting)\ntransition is driven by the Rashba spin-orbit interaction, which breaks U_z(1)."
    },
    {
        "anchor": "Localized domain-wall excitations in patterned magnetic dots probed by\n  broadband ferromagnetic resonance: We investigate the magnetization dynamics in circular Permalloy dots with\nspatially separated magnetic vortices interconnected by domain walls (double\nvortex state). We identify a novel type of quasi one-dimensional (1D) localised\nspin wave modes confined along domain walls, connecting each of two vortex\ncores with two edge half-antivortices. Variation of the mode eigenfrequencies\nwith the dot size is in quantitative agreement with the developed model, which\nconsiders a dipolar origin of the localized 1D spin waves or so-called\nWinter\\'s magnons [J.M. Winter, Phys.Rev. 124, 452 (1961)]. These spin waves\nare analogous to the displacement waves of strings, and could be excited in a\nwide class of patterned magnetic nanostructures possessing domain walls, namely\nin triangular, square, circular or elliptic magnetic dots.",
        "positive": "A topological insulator surface under strong Coulomb, magnetic and\n  disorder perturbations: Three dimensional topological insulators embody a newly discovered state of\nmatter characterized by conducting spin-momentum locked surface states that\nspan the bulk band gap as demonstrated via spin-resolved ARPES measurements .\nThis highly unusual surface environment provides a rich ground for the\ndiscovery of novel physical phenomena. Here we present the first controlled\nstudy of the topological insulator surfaces under strong Coulomb, magnetic and\ndisorder perturbations. We have used interaction of iron, with a large Coulomb\nstate and significant magnetic moment as a probe to \\textit{systematically test\nthe robustness} of the topological surface states of the model topological\ninsulator Bi$_2$Se$_3$. We observe that strong perturbation leads to the\ncreation of odd multiples of Dirac fermions and that magnetic interactions\nbreak time reversal symmetry in the presence of band hybridization. We also\npresent a theoretical model to account for the altered surface of Bi$_2$Se$_3$.\nTaken collectively, these results are a critical guide in manipulating\ntopological surfaces for probing fundamental physics or developing device\napplications."
    },
    {
        "anchor": "Effects of spin-orbit torque on the ferromagnetic and exchange spin wave\n  modes in ferrimagnetic CoGd alloy: We use micro-focus Brillouin light scattering spectroscopy to study the\neffects of spin-orbit torque on thermal spin waves in almost angular-momentum\ncompensated ferrimagnetic CoGd alloy films. The spin-orbit torque is produced\nby the electric current flowing in the Pt layer adjacent to CoGd. Both the\nferromagnetic and the exchange modes are detected in our measurements. The\nintensity and the linewidth of the ferromagnetic mode are modified by the\nspin-orbit torque. In contrast, the properties of the exchange mode are\nunaffected by the spin-orbit torque. We also find that the frequencies and the\nlinewidths of both modes are significantly modified by Joule heating, due to\nthe strong temperature dependence of the magnetic properties of CoGd in the\nvicinity of angular momentum compensation point. Our results provide insight\ninto the mechanisms that can enable the implementation of sub-THz magnetic\nnano-oscillators based on ferrimagnetic materials, as well as related effects\nin antiferromagnets.",
        "positive": "Negative Differential Resistance in Boron Nitride Graphene\n  Heterostructures: Physical Mechanisms and Size Scaling Analysis: Hexagonal boron nitride (hBN) is drawing increasing attention as an insulator\nand substrate material to develop next generation graphene-based electronic\ndevices. In this paper, we investigate the quantum transport in\nheterostructures consisting of a few atomic layers thick hBN film sandwiched\nbetween graphene nanoribbon electrodes. We show a gate-controllable vertical\ntransistor exhibiting strong negative differential resistance (NDR) effect with\nmultiple resonant peaks, which stay pronounced for various device dimensions.\nWe find two distinct mechanisms that are responsible for NDR, depending on the\ngate and applied biases, in the same device. The origin of first mechanism is a\nFabry-P\\'e like interference and that of the second mechanism is an in-plane\nwave vector matching when the Dirac points of the electrodes align. The hBN\nlayers can induce an asymmetry in the current-voltage characteristics which can\nbe further modulated by an applied bias. We find that the electron-phonon\nscattering introduces the decoherence and therefore suppresses first mechanism\nwhereas second mechanism remains relatively unaffected. We also show that the\nNDR features are tunable by varying device dimensions. The NDR feature with\nmultiple resonant peaks, combined with the ultrafast tunneling speed provides\nprospect for the graphene-hBN-graphene heterostructure in the high-performance\nelectronics."
    },
    {
        "anchor": "Controlling Chiral Domain Walls in Antiferromagnets Using Spin-Wave\n  Helicity: In antiferromagnets, the Dzyaloshinskii-Moriya interaction lifts the\ndegeneracy of left- and right-circularly polarized spin waves. This\nrelativistic coupling increases the efficiency of spin-wave-induced domain wall\nmotion and leads to higher drift velocities. We show that in biaxial\nantiferromagnets, the spin-wave helicity controls both the direction and\nmagnitude of the magnonic force on chiral domain walls. By contrast, in\nuniaxial antiferromagnets, the magnonic force is propulsive with a helicity\ndependent strength.",
        "positive": "Finite bias Cooper pair splitting: In a device with a superconductor coupled to two parallel quantum dots (QDs)\nthe electrical tunability of the QD levels can be used to exploit non-classical\ncurrent correlations due to the splitting of Cooper pairs. We experimentally\ninvestigate the effect of a finite potential difference across one quantum dot\non the conductance through the other completely grounded QD in a Cooper pair\nsplitter fabricated on an InAs nanowire. We demonstrate that the electrical\ntransport through the device can be tuned by electrical means to be dominated\neither by Cooper pair splitting (CPS), or by elastic co-tunneling (EC). The\nbasic experimental findings can be understood by considering the energy\ndependent density of states in a QD. The reported experiments add\nbias-dependent spectroscopy to the investigative tools necessary to develop\nCPS-based sources of entangled electrons in solid-state devices."
    },
    {
        "anchor": "Current-Driven Skyrmion Dynamics and Drive-Dependent Skyrmion Hall\n  Effect in an Ultrathin Film: Magnetic skyrmions are chiral spin textures that hold great promise as\nnanoscale information carriers. Since their first observation at room\ntemperature, progress has been made in their current-induced manipulation, with\nfast motion reported in stray-field-coupled multilayers. However, the complex\nspin textures with hybrid chiralities and large power dissipation in these\nmultilayers limit their practical implementation and the fundamental\nunderstanding of their dynamics. Here, we report on the current-driven motion\nof N\\'eel skyrmions with diameters in the 100-nm range in an ultrathin\nPt/Co/MgO trilayer. We find that these skyrmions can be driven at a speed of\n100 m/s and exhibit a drive-dependent skyrmion Hall effect, which is accounted\nfor by the effect of pinning. Our experiments are well substantiated by an\nanalytical model of the skyrmion dynamics as well as by micromagnetic\nsimulations including material inhomogeneities. This good agreement is enabled\nby the simple skyrmion spin structure in our system and a thorough\ncharacterization of its static and dynamical properties.",
        "positive": "Double Barriers and Magnetic Field in Bilayer Graphene: We study the transmission probability in an AB-stacked bilayer graphene of\nDirac fermions scattered by a double barrier structure in the presence of a\nmagnetic field. We take into account the full four bands of the energy spectrum\nand use the boundary conditions to determine the transmission probability. Our\nnumerical results show that for energies higher than the interlayer coupling,\nfour ways for transmission probabilities are possible while for energies less\nthan the height of the barrier, Dirac fermions exhibits transmission resonances\nand only one transmission channel is available. We show that, for AB-stacked\nbilayer graphene, there is no Klein tunneling at normal incident. We find that\nthe transmission displays sharp peaks inside the transmission gap around the\nDirac point within the barrier regions while they are absent around the Dirac\npoint in the well region. The effect of the magnetic field, interlayer\nelectrostatic potential and various barrier geometry parameters on the\ntransmission probabilities are also discussed."
    },
    {
        "anchor": "Enhanced scattering between electrons and exciton-polaritons in a\n  microcavity: The interplay between strong light-matter interactions and charge doping\nrepresents an important frontier in the pursuit of exotic many-body physics and\noptoelectronics. Here, we consider a simplified model of a two-dimensional\nsemiconductor embedded in a microcavity, where the interactions between\nelectrons and holes are strongly screened, allowing us to develop a\ndiagrammatic formalism for this system with an analytic expression for the\nexciton-polariton propagator. We apply this to the scattering of spin-polarized\npolaritons and electrons, and show that this is strongly enhanced compared with\nexciton-electron interactions. As we argue, this counter-intuitive result is a\nconsequence of the shift of the collision energy due to the strong light-matter\ncoupling, and hence this is a generic feature that applies also for more\nrealistic electron-hole and electron-electron interactions. We furthermore\ndemonstrate that the lack of Galilean invariance inherent in the light-matter\ncoupled system can lead to a narrow resonance-like feature for\npolariton-electron interactions close to the polariton inflection point. Our\nresults are potentially important for realizing tunable light-mediated\ninteractions between charged particles.",
        "positive": "Gold nanocrescents for remotely measuring and controlling local\n  temperature: We present a novel technique to remotely measure and control the local\ntemperature within a medium. This technique is based on the observation of the\nrotational Brownian motion of gold nanocrescent particles, which possess a\nstrong anisotropic light interaction due to their plasmonic properties.\nRotational scattering correlation spectroscopy performed on a single\nnanoparticle is able to determine the local temperature with high accuracy.\nThese nano-thermometers can simultaneously play the role of nano-heaters when\nabsorbing the light of a focused laser beam."
    },
    {
        "anchor": "Topological invariants for three dimensional Dirac semimetals and four\n  dimensional topological rotational insulators: Dirac semimetal is a class of semi-metallic phase protected by certain types\nof crystalline symmetries, and its low-energy effective Hamiltonian is\ndescribed by Dirac equations in three dimensions (3D). Despite of various\ntheoretical studies, theories that describe the topological nature of Dirac\nsemimetals have not been well established. In this work, we define a\ntopological invariant for 3D Dirac semimetals by establishing a mapping between\na 3D Dirac semimetal and a topological crystalline insulator in four dimension\n(4D). We demonstrate this scheme by constructing a tight-binding model for 4D\ntopological crystalline insulators that are protected by rotational symmetry. A\nnew type of topological invariant, \"rotational Chern number\", is shown to\ncharacterize the topology of this system. As a consequence of the rotational\nChern number, gapless Dirac points are found on the 3D surface of this 4D\nsystem. For a slab with two surfaces, we find that the corresponding low-energy\neffective theory of two surface states can be directly mapped to that of a 3D\nDirac semimetal, suggesting that topological nature of 3D Dirac semimetals can\nbe characterized by rotational Chern number which is defined in 4D. Our scheme\nprovides a new systematic approach to extract topological nature for\ntopological semimetal phases.",
        "positive": "Analysis of the interaction of an electron with radial electric fields\n  in the presence of a disclination: We consider an elastic medium with a disclination and investigate the\ntopological effects on the interaction of a spinless electron with radial\nelectric fields through the WKB (Wentzel, Kramers, Brillouin) approximation. We\nshow how the centrifugal term of the radial equation must be modified due to\nthe influence of the topological defect in order that the WKB approximation can\nbe valid. Then, we search for bound states solutions from the interaction of a\nspinless electron with the electric field produced by this linear distribution\nof electric charges. In addition, we search for bound states solutions from the\ninteraction of a spinless electron with radial electric field produced by\nuniform electric charge distribution inside a long non-conductor cylinder."
    },
    {
        "anchor": "Magnetic quantum ratchet effect in Si-MOSFETs: We report on the observation of magnetic quantum ratchet effect in\nmetal-oxide-semiconductor field-effect-transistors on silicon surface\n(Si-MOSFETs). We show that the excitation of an unbiased transistor by ac\nelectric field of terahertz radiation at normal incidence leads to a direct\nelectric current between the source and drain contacts if the transistor is\nsubjected to an in-plane magnetic field. The current rises linearly with the\nmagnetic field strength and quadratically with the ac electric field amplitude.\nIt depends on the polarization state of the ac field and can be induced by both\nlinearly and circularly polarized radiation. We present the quasi-classical and\nquantum theories of the observed effect and show that the current originates\nfrom the Lorentz force acting upon carriers in asymmetric inversion channels of\nthe transistors.",
        "positive": "Superconductor coupled to two Luttinger liquids as an entangler for\n  electron spins: We consider an s-wave superconductor (SC) which is tunnel-coupled to two\nspatially separated Luttinger liquid (LL) leads. We demonstrate that such a\nsetup acts as an entangler, i.e. it creates spin-singlets of two electrons\nwhich are spatially separated, thereby providing a source of electronic\nEinstein-Podolsky-Rosen pairs. We show that in the presence of a bias voltage,\nwhich is smaller than the energy gap in the SC, a stationary current of\nspin-entangled electrons can flow from the SC to the LL leads due to Andreev\ntunneling events. We discuss two competing transport channels for Cooper pairs\nto tunnel from the SC into the LL leads. On the one hand, the coherent\ntunneling of two electrons into the same LL lead is shown to be suppressed by\nstrong LL correlations compared to single-electron tunneling into a LL. On the\nother hand, the tunneling of two spin-entangled electrons into different leads\nis suppressed by the initial spatial separation of the two electrons coming\nfrom the same Cooper pair. We show that the latter suppression depends\ncrucially on the effective dimensionality of the SC. We identify a regime of\nexperimental interest in which the separation of two spin-entangled electrons\nis favored. We determine the decay of the singlet state of two electrons\ninjected into different leads caused by the LL correlations. Although the\nelectron is not a proper quasiparticle of the LL, the spin information can\nstill be transported via the spin density fluctuations produced by the injected\nspin-entangled electrons."
    },
    {
        "anchor": "Directional dependence of the plasmonic gain and nonreciprocity in\n  drift-current biased graphene: Here, we investigate the nonreciprocal propagation and amplification of\nsurface plasmons in drift-current biased graphene, using both Galilean and\nrelativistic-type Doppler shift transformations of the graphene's conductivity.\nConsistent with previous studies, both conductivity models predict strongly\nnonreciprocal propagation of surface plasmons due to the drag effect caused by\nthe drifting electrons. In particular, the Galilean Doppler shift model leads\nto stronger spectral asymmetries in the plasmon dispersion with regimes of\nunidirectional propagation. Remarkably, it is shown that both conductivity\nmodels predict regimes of nonreciprocal plasmon amplification in a wide angular\nsector of in-plane directions when the drift-current biased graphene sheet is\ncoupled to a plasmonic substrate (namely, SiC), with the plasmon amplification\nrate being substantially higher for the relativistic Doppler shift model.",
        "positive": "Strain Effect on Transmission in Graphene Laser Barrier: We investigate the strain effect along armchair and zigzag directions on the\ntunneling transport of Dirac fermions in graphene laser barrier through a time\ndependent potential along y-axis. Our system is composed of three regions and\nthe central one is subjected to a deformation of strength S. Based on Dirac\nequation and the Floquet approach, we determine the eigenvalues and\neigenspinors for each region. Using the boundary conditions at interfaces\ntogether with the transfer matrix method we identify the transmission in the\ndifferent Floquet sideband states as function of the physical parameters. In\nthe strainless case, we show that the transmisson of central band decreases for\nsmaller values of the barrier width and rapidly oscillates with different\namplitude for larger ones. Whereas the transmission for the first sidebands\nincreases from zero and shows a damped oscillatory profile. It is found that\nthe number of oscillations in all transmission channels reduces with increasing\nthe strength of armchair strain but becomes more important by switching the\ndeformation to zigzag. Moreover, it is observed the appearance of Fano type\nresonance peaks by altering the amplitude and the frequency of the laser field."
    },
    {
        "anchor": "Linear in-plane magnetoconductance and spin susceptibility of a 2D\n  electron gas on a vicinal silicon surface: In this work we have studied the parallel magnetoresistance of a 2DEG near a\nvicinal silicon surface. An unusual, linear magnetoconductance is observed in\nthe fields up to $B = 15$ T, which we explain by the effect of spin olarization\non impurity scattering. This linear magnetoresistance shows strong anomalies\nnear the boundaries of the minigap in the electron spectrum of the vicinal\nsystem.",
        "positive": "Optically Probing Tunable Band Topology in Atomic Monolayers: In many atomically thin materials their optical absorption is dominated by\nexcitonic transitions. It was recently found that optical selection rules in\nthese materials are influenced by the band topology near the valleys. We\npropose that gate-controlled band ordering in a single atomic monolayer,\nthrough changes in the valley winding number and excitonic transitions, can be\nprobed in helicity-resolved absorption and photoluminescence. This predicted\ntunable band topology is confirmed by combining an effective Hamiltonian and a\nBethe-Salpeter equation for an accurate description of excitons, with\nfirst-principles calculations suggesting its realization in Sb-based\nmonolayers."
    },
    {
        "anchor": "Energy flow and thermo-electricity in atomic and molecular junctions: Advances in the fabrication and characterization of nanoscale systems now\nallow for a deeper understanding of one of the most basic issues in science and\ntechnology: the flow of energy at the microscopic level. In this Colloquium we\nsurvey recent advances and present understanding of physical mechanisms of\nenergy transport in nanostructures, focusing mainly on molecular junctions and\natomic wires. We examine basic issues such as thermal conductivity,\nthermoelectricity, local temperature and heating, and the relation between\nenergy current density and temperature gradient - known as Fourier's law. We\ncritically report on both theoretical and experimental progress in each of\nthese issues, and discuss future research opportunities in the field.",
        "positive": "Enhanced piezoelectricity and modified dielectric screening of 2-D\n  group-IV monochalcogenides: We use first principles calculations to investigate the lattice properties of\ngroup-IV monochalcogenides. These include static dielectric permittivity,\nelastic and piezoelectric tensors. For the monolayer, it is found that the\nstatic permittivity, besides acquiring a dependence on the interlayer distance,\nis comparatively higher than in the 3D system. In contrast, it is found that\nelastic properties are little changed by the lower dimensionality. Poisson\nratio relating in-plane deformations are close to zero, and the existence of a\nnegative Poisson ratio is also predicted for the GeS compound. Finally, the\nmonolayers shows piezoelectricity, with piezoelectric constants higher than\nthat recently predicted to occur in other 2D-systems, as hexagonal BN and\ntransition metal dichalcogenide monolayers."
    },
    {
        "anchor": "Structured environments in solid state systems: crossover from Gaussian\n  to non-Gaussian behavior: The variety of noise sources typical of the solid state represents the main\nlimitation toward the realization of controllable and reliable quantum\nnanocircuits, as those allowing quantum computation. Such ``structured\nenvironments'' are characterized by a non-monotonous noise spectrum sometimes\nshowing resonances at selected frequencies. Here we focus on a prototype\nstructured environment model: a two-state impurity linearly coupled to a\ndissipative harmonic bath. We identify the time scale separating Gaussian and\nnon-Gaussian dynamical regimes of the Spin-Boson impurity. By using a\npath-integral approach we show that a qubit interacting with such a structured\nbath may probe the variety of environmental dynamical regimes.",
        "positive": "Revealing 3D Magnetization of Thin Films with Soft X-ray Tomography:\n  Closure Domains and Magnetic Singularities: The knowledge of how the magnetization looks inside a ferromagnet is often\nhindered by the limitations of the available experimental methods that are\nsensitive only to the surface regions or limited in spatial resolution. We\nreport the 3D tomographic reconstruction of the magnetization within a\nferromagnetic film of 240 nm in thickness using soft X ray microscopy and\nmagnetic dichroism. The film has periodic magnetic domains forming stripes and\nclosure domains found to be shifted from the stripe array by 1/4 of the period.\nIn addition, the bifurcations of the stripes, which act as inversion nuclei of\nthe magnetization, evidence in 3D meron singularities and Bloch points at the\ninterior of the film. This novel method can be easily extended to magnetic\nstacks in spintronics applications and other singularities in films."
    },
    {
        "anchor": "Photoinduced valley-polarized current of layered MoS2 by electric tuning: A photoinduced current of a layered MoS2-based transistor is studied from\nfirst-principles. Under the illumination of circular polarized light, a\nvalley-polarized current is generated, which can be tuned by the gate voltage.\nFor monolayer MoS2, the valley-polarized spin-up (down) electron current at K\n(K') points is induced by the right (left) circular polarized light. The valley\npolarization is found to reach +1.0 (-1.0) for the valley current that carried\nsuch a K (K') index. For bilayer MoS2, the spin-up (down) current can be\ninduced at both K and K' valleys by the right (left) circular light. In\ncontrast to monolayer MoS2, the photoinduced valley polarization shows\nasymmetric behavior upon reversal of the gate voltage. Our results show that\nthe valley polarization of the photoinduced current can be modulated by the\ncircular polarized light and the gate voltage. All the results can be well\nunderstood using a simple kp model.",
        "positive": "Andreev Reflection in Fermi Arc Surface States of Weyl Semimetals: Fermi arc surface states are the hallmark of Weyl semimetals, whose\nidentification is usually challenged by their coexistence with gapless bulk\nstates. Surface transport measurements by fabricating setups on the sample\nboundary provide a natural solution to this problem. Here, we study the Andreev\nreflection (AR) in a planar normal metal-superconductor junction on the Weyl\nsemimetal surface with a pair of Fermi arcs. For a conserved transverse\nmomentum, the occurrence of normal reflection depends on the relative\norientation between the Fermi arcs and the normal of the junction, which is a\ndirect result of the disconnected Fermi arcs. Consequently, a crossover from\nthe suppressed to perfect AR occurs with varying the orientation of the planar\njunction, giving rise to a change from double-peak to plateau structure in\nconductance spectra. Moreover, such a crossover can be facilitated by imposing\na magnetic field, making electrons slide along the Fermi arcs so as to switch\nbetween two regimes of the AR. Our results provide a decisive signature for the\ndetection of Fermi arcs and open the possibilities of exploring novel\nphenomenology through their interplay with superconductivity."
    },
    {
        "anchor": "Scattering description of edge states in Aharonov-Bohm triangle chains: Scattering theory has been suggested as a convenient method to identify\ntopological phases of matter, in particular of disordered systems for which the\nBloch band-theory approach is inapplicable. Here we examine this idea,\nemploying as a benchmark a one-dimensional triangle chain whose versatility\nyields a scattering matrix that ``flows\" in parameter space among several\nmembers of the topology classification scheme. Our results show that the\nreflection amplitudes (from both ends of a sufficiently long chain) do indicate\nthe appearance of edge states in {\\it all} (topological and non-topological)\ncases. For the topological cases, the transmission has a peak at the\ntopological phase transition, which happens at the Fermi energy. A peak still\nexists as one moves into the non-topological `trivial' regions, in which\nanother transmission peak may occur at nonzero energy, at which a relevant edge\nstate appears in the isolated chain. For finite chains, the peak in the\ntransmission strongly depends on their coupling of the leads, and {\\it not} on\nthe phase transition of the isolated chain. In any case, {\\it the appearance of\na peak in the transmission is not sufficient to conclude that the system\nundergoes a topological phase transition.}",
        "positive": "All electrical propagating spin wave spectroscopy with broadband\n  wavevector capability: We develop an all electrical experiment to perform the broadband\nphase-resolved spectroscopy of propagating spin waves in micrometer sized thin\nmagnetic stripes. The magnetostatic surface spin waves are excited and detected\nby scaled down to 125 nm wide inductive antennas, which award ultra broadband\nwavevector capability. The wavevector selection can be done by applying an\nexcitation frequency above the ferromagnetic resonance. Wavevector\ndemultiplexing is done at the spin wave detector thanks to the rotation of the\nspin wave phase upon propagation. A simple model accounts for the main features\nof the apparatus transfer functions. Our approach opens an avenue for the all\nelectrical study of wavevector-dependent spin wave properties including\ndispersion spectra or non-reciprocal propagation."
    },
    {
        "anchor": "Two-band description of the strong `spin'-orbit coupled one-dimensional\n  hole gas in a cylindrical Ge nanowire: The low-energy effective Hamiltonian of the strong `spin'-orbit coupled\none-dimensional hole gas in a cylindrical Ge nanowire in the presence of a\nstrong magnetic field is studied both numerically and analytically. Basing on\nthe Luttinger-Kohn Hamiltonian in the spherical approximation, we show this\nstrong `spin'-orbit coupled one-dimensional hole gas can be accurately\ndescribed by an effective two-band Hamiltonian $H^{\\rm\nef}=\\hbar^{2}k^{2}_{z}/(2m^{*}_{h})+\\alpha\\sigma^{x}k_{z}+g^{*}_{h}\\mu_{B}B\\sigma^{z}/2$,\nas long as the magnetic field is purely longitudinal or purely transverse. The\nexplicit magnetic field dependent expressions of the `spin'-orbit coupling\n$\\alpha\\equiv\\alpha(B)$ and the effective $g$-factor\n$g^{*}_{h}\\equiv\\,g^{*}_{h}(B)$ are given. When the magnetic field is applied\nin an arbitrary direction, the two-band Hamiltonian description is still a good\napproximation.",
        "positive": "Theory of electrical spin-detection at a ferromagnet/semiconductor\n  interface: We present a theoretical model that describes electrical spin-detection at a\nferromagnet/semiconductor interface. We show that the sensitivity of the spin\ndetector has strong bias dependence which, in the general case, is dramatically\ndifferent from that of the tunneling current spin polarization. We show that\nthis bias dependence originates from two distinct physical mechanisms: 1) the\nbias dependence of tunneling current spin polarization, which is of microscopic\norigin and depends on the specific properties of the interface, and 2) the\nmacroscopic electron spin transport properties in the semiconductor. Numerical\nresults show that the magnitude of the voltage signal can be tuned over a wide\nrange from the second effect which suggests a universal method for enhancing\nelectrical spin-detection sensitivity in ferromagnet/semiconductor tunnel\ncontacts. Using first-principles calculations we examine the particular case of\na Fe/GaAs Schottky tunnel barrier and find very good agreement with experiment.\nWe also predict the bias dependence of the voltage signal for a Fe/MgO/GaAs\ntunnel structure spin detector."
    },
    {
        "anchor": "Ratchet effects in two-dimensional systems with a lateral periodic\n  potential: Radiation-induced ratchet electric currents have been studied theoretically\nin graphene with a periodic noncentrosymmetric lateral potential. The ratchet\ncurrent generated under normal incidence is shown to consist of two\ncontributions, one of them being polarization-independent and proportional to\nthe energy relaxation time, and another controlled solely by elastic scattering\nprocesses and sensitive to both the linear and circular polarization of\nradiation. Two realistic mechanisms of electron scattering in graphene are\nconsidered. For short-range defects, the ratchet current is helicity-dependent\nbut independent of the direction of linear polarization. For the Coulomb\nimpurity scattering, the ratchet current is forbidden for the radiation\nlinearly polarized in the plane perpendicular to the lateral-potential\nmodulation direction. For comparison, the ratchet currents in a quantum well\nwith a lateral superlattice are calculated at low temperatures with allowance\nfor the dependence of the momentum relaxation time on the electron energy.",
        "positive": "Three-dimensional $\\mathbb{Z}$ topological insulators without reflection\n  symmetry: In recent decades, the Altland-Zirnabuer (AZ) table has proven incredibly\npowerful in delineating constraints for topological classification of a given\nband-insulator based on dimension and (nonspatial) symmetry class, and has also\nbeen expanded by considering additional crystalline symmetries. Nevertheless,\nrealizing a three-dimensional (3D), time-reversal symmetric (class AII)\ntopological insulator (TI) in the absence of reflection symmetries, with a\nclassification beyond the $\\mathbb{Z}_{2}$ paradigm remains an open problem. In\nthis work we present a general procedure for constructing such systems within\nthe framework of projected topological branes (PTBs). In particular, a 3D\nprojected brane from a \"parent\" four-dimensional topological insulator exhibits\na $\\mathbb{Z}$ topological classification, corroborated through its response to\nthe inserted bulk monopole loop. More generally, PTBs have been demonstrated to\nbe an effective route to performing dimensional reduction and embedding the\ntopology of a $(d+1)$-dimensional \"parent\" Hamiltonian in $d$ dimensions,\nyielding lower-dimensional topological phases beyond the AZ classification\nwithout additional symmetries. Our findings should be relevant for the\nmetamaterial platforms, such as photonic and phonic crystals, topolectric\ncircuits, and designer systems."
    },
    {
        "anchor": "Nanomechanical displacement detection using coherent transport in\n  ordered and disordered graphene nanoribbon resonators: Graphene nanoribbons provide an opportunity to integrate phase-coherent\ntransport phenomena with nanoelectromechanical systems (NEMS). Due to the\nstrain induced by a deflection in a graphene nanoribbon resonator, coherent\nelectron transport and mechanical deformations couple. As the electrons in\ngraphene have a Fermi wavelength \\lambda ~ a_0 = 1.4 {\\AA}, this coupling can\nbe used for sensitive displacement detection in both armchair and zigzag\ngraphene nanoribbon NEMS. Here it is shown that for ordered as well as\ndisordered ribbon systems of length L, a strain \\epsilon ~ (w/L)^2 due to a\ndeflection w leads to a relative change in conductance \\delta G/G ~ (w^2/a_0L).",
        "positive": "Spin and impurity effects on flux-periodic oscillations in core-shell\n  nanowires: We study the quantum mechanical states of electrons situated on a cylindrical\nsurface of finite axial length to model a semiconductor core-shell nanowire. We\ncalculate the conductance in the presence of a longitudinal magnetic field by\nweakly coupling the cylinder to semi-infinite leads. Spin effects are accounted\nfor through Zeeman coupling and Rashba spin-orbit interaction (SOI). Emphasis\nis on manifestations of flux-periodic (FP) oscillations and we show how factors\nsuch as impurities, contact geometry and spin affect them. Oscillations survive\nand remain periodic in the presence of impurities, noncircular contacts and\nSOI, while Zeeman splitting results in aperiodicity, beating patterns and\nadditional background fluctuations. Our results are in qualitative agreement\nwith recent magnetotransport experiments performed on GaAs/InAs core-shell\nnanowires. Lastly, we propose methods of data analysis for detecting the\npresence of Rashba SOI in core-shell systems and for estimating the electron\ng-factor in the shell."
    },
    {
        "anchor": "Artifact Free Transient Near-Field Nanoscopy: We report on the first implementation of ultrafast near field nanoscopy\ncarried out with the transient pseudoheterodyne detection method (Tr-pHD). This\nmethod is well suited for efficient and artifact free pump-probe\nscattering-type near-field optical microscopy with nanometer scale resolution.\nThe Tr-pHD technique is critically compared to other data acquisition methods\nand found to offer significant advantages. Experimental evidence for the\nadvantages of Tr-pHD is provided in the Near-IR frequency range. Crucial\nfactors involved in achieving proper performance of the Tr-pHD method with\npulsed laser sources are analyzed and detailed in this work. We applied this\nnovel method to time-resolved and spatially resolved studies of the\nphoto-induced effects in the insulator-to-metal transition system vanadium\ndioxide with nanometer scale resolution.",
        "positive": "Ultrafast Energy Transfer Between Molecular Assemblies and Surface\n  Plasmons in the Strong Coupling Regime: The nonlinear optical dynamics of nano-materials comprised of plasmons\ninteracting with quantum emitters is investigated by a self-consistent model\nbased on the coupled Maxwell-Liouville-von Neumann equations. It is shown that\nultra-short resonant laser pulses significantly modify the optical properties\nof such hybrid systems. It is further demonstrated that the energy transfer\nbetween interacting molecules and plasmons occurs on a femtosecond time scale\nand can be controlled with both material and laser parameters."
    },
    {
        "anchor": "Pressure Induced Compression of Flatbands in Twisted Bilayer Graphene: We investigate the bandwidth compression due to out of plane pressure of the\nmoire flatbands near charge neutrality in twisted bilayer graphene for a\ncontinuous range of small rotation angles of up to $\\sim2.5^{\\circ}$. The\nflatband bandwidth minima angles are found to grow linearly with interlayer\ncoupling {\\omega} and decrease with Fermi velocity. Application of moderate\npressure values of up to 2.5 GPa achievable through a hydraulic press should\nallow accessing a flatband for angles as large as $\\sim 1.5$^{\\circ}$ instead\nof $\\sim 1 \\circ$ at zero pressure. This reduction of the moir\\'e pattern\nlength for larger twist angle implies an increase of the effective Coulomb\ninteraction scale per moire cell by about 50% and enhance roughly by a factor\nof $\\sim 2$ the elastic energy that resists the commensuration strains due to\nthe moire pattern. Our results suggest that application of pressure on twisted\nbilayer graphene nanodevices through a hydraulic press will notably facilitate\nthe device preparation efforts required for exploring the ordered phases near\nmagic angle flatbands.",
        "positive": "Modeling Electronic and Thermal Characteristics of Ge/Si-Core/Shell\n  Nanowire Quantum Dot in the Coulomb Blockade Regime: We investigate the transport characteristics of Ge/Si-Core/Shell nanowire\nwith Coulomb Blockade in presence of external magneto-electric fields from a\ntheoretical basis. Using the effective Luttinger-Kohn Hamiltonian we calculate\nthe valence band energy states of the nanowire and find out the state density\nat mili-Kelvin temperature. We explore the current-voltage and\nconductance-voltage characteristics. The observed transport characteristics are\nin close agreement with experimental data. We find these characteristics to be\nsensitive to the coupling of the quantum dot with the reservoirs. The quantum\nnature of the characteristics becomes less prominent with increasing\ntemperature, as expected."
    },
    {
        "anchor": "Quantum Hall coherent perfect absorption in graphene: 100 % absorption in a two-dimensional electron gas (2DEG) with Dirac spectrum\nis demonstrated to be obtained by controlling the interference of multiple\nincident radiations, referred to as coherent perfect absorption (CPA). However,\nwhen a 2DEG such as graphene is exposed to a magnetostatic bias, it resonantly\ncould absorb electromagnetic radiation by transitions of its Dirac electrons\nbetween non-equidistant and nonlinear Landau levels. Here, the magneto-optical\nterahertz (THz) CPA in graphene under the quantum Hall effect (QHE) regime at\nboth strong and subtesla magnetostatic bias fields is addressed. Our findings\nshow that an effective magneto-optical surface conductivity corresponding to\nright- and left-handed circular (RHC- and LHC) polarizations could model a\nmagneto-tunable CPA in graphene in THz range. Significantly, graphene under QHE\nregime reveals different tunable CPA properties for each circularly polarized\nbeams by the intensity of the applied magnetic bias. Moreover, it is observed\nthat different phase modulations at CPA frequencies are achieved for RHC and\nLHC polarizations. Considering the maximum efficiency for a 2D absorber, our\nresults demonstrate the magnetostatic tuning of CPA in 2D Dirac materials for\nlong-wavelength sensing applications and signal processing.",
        "positive": "Unveiling the Electric-current-limiting and Photodetection Effect in\n  Two-dimensional Hydrogenated Borophene: The electronic transport and photoelectric properties of hydrogenated\nborophene B4H4, which was realized in a recent experiment by Nishino [J. Am.\nChem. Soc. 139, 13761 (2017)], are systematically investigated using the\ndensity functional theory and non-equilibrium Green's function methods. We find\nthat B4H4 exhibits a perfect current-limiting effect and has high (along the\nzigzag direction) and low (along the armchair one) optional levels due to its\nstrong electrical anisotropy. Moreover, B4H4 can generate sizable photocurrents\nunder illumination, with strong photoelectronic response to blue/green light\nalong the zigzag/armchair direction. Our work demonstrates that B4H4 is\npromising for the applications of current limiter and photodetectors."
    },
    {
        "anchor": "Reducing the critical switching current in nanoscale spin valves: The current induced magnetization reversal in nanoscale spin valves is a\npotential alternative to magnetic field switching in magnetic memory devices.\nWe show that the critical switching current can be decreased by an order of\nmagnitude by strategically distributing the resistances in the magnetically\nactive region of the spin valve. In addition, we simulate full switching curves\nand predict a new precessional state.",
        "positive": "Proposal for manipulating and detecting spin and orbital states of\n  trapped electrons on helium using cavity quantum electrodynamics: We propose to couple an on-chip high finesse superconducting cavity to the\nlateral-motion and spin state of a single electron trapped on the surface of\nsuperfluid helium. We estimate the motional coherence times to exceed 15\nmicroseconds, while energy will be coherently exchanged with the cavity photons\nin less than 10 nanoseconds for charge states and faster than 1 microsecond for\nspin states, making the system attractive for quantum information processing\nand cavity quantum electrodynamics experiments. Strong interaction with cavity\nphotons will provide the means for both nondestructive readout and coupling of\ndistant electrons."
    },
    {
        "anchor": "Self-organisation of highly symmetric nanoassemblies: a matter of\n  competition: The properties and applications of metallic nanoparticles are inseparably\nconnected not only to their detailed morphology and composition, but also to\ntheir structural configuration and mutual interactions. As a result, the\nassemblies often have superior properties as compared to individual\nnanoparticles. Although it has been reported that nanoparticles can form highly\nsymmetric clusters, if the configuration can be predicted as a function of the\nsynthesis parameters, more targeted and accurate synthesis will be possible. We\npresent here a theoretical model that accurately predicts the structure and\nconfiguration of self-assembled gold nanoclusters. The validity of the model is\nverified using quantitative experimental data extracted from electron\ntomography 3D reconstructions of different assemblies. The present theoretical\nmodel is generic and can in principle be used for different types of\nnanoparticles, providing a very wide window of potential applications.",
        "positive": "Momentum-space Gravity from the Quantum Geometry and Entropy of Bloch\n  Electrons: Quantum geometry is a key quantity that distinguishes electrons in a crystal\nfrom those in the vacuum. Its study continues to provide insights into quantum\nmaterials, uncovering new design principles for their discovery. However,\nunlike the Berry curvature, an intuitive understanding of the quantum metric is\nlacking. Here, we show that the quantum metric of Bloch electrons leads to a\nmomentum-space gravity. In particular, by extending the semiclassical\nformulation of electron dynamics to second order, we find that the resulting\nvelocity is modified by a geodesic term and becomes the momentum-space dual of\nthe Lorentz force in curved space. We calculate this geodesic response for\nmagic-angle twisted bilayer graphene and show that moir\\'e systems with flat\nbands are ideal candidates to observe this effect. Extending this analogy with\ngravity further, we find that the momentum-space dual of the Einstein field\nequations remains sourceless for pure states while for mixed states it acquires\na source term that depends on the von Neumann entropy, for small entropies. We\ncompare this stress-energy equation with the weak-field limit of general\nrelativity and conclude that the von Neumann entropy is the momentum-space dual\nof the gravitational potential. Consequently, the momentum-space geodesic\nequation for mixed states is modified by a term resembling an entropic force.\nOur results highlight connections between quantum geometry, momentum-space\ngravity and quantum information, prompting further exploration of this dual\ngravity in quantum materials."
    },
    {
        "anchor": "Hot carriers in a bipolar graphene: Hot carriers in a doped graphene under dc electric field is described taking\ninto account the intraband energy relaxation due to acoustic phonon scattering\nand the interband generation-recombination transitions caused by thermal\nradiation. The consideration is performed for the case when the intercarrier\nscattering effectively establishes the quasiequilibrium electron-hole\ndistributions, with effective temperature and concentrations of carriers. The\nconcentration and energy balance equations are solved taking into account an\ninterplay between weak energy relaxation and generation-recombination\nprocesses. The nonlinear conductivity is calculated for the momentum relaxation\ncaused by the elastic scattering. The current-voltage characteristics, and the\ntransition between bipolar and monopolar regimes of conductivity are obtained\nand analyzed, for different temperatures and gate voltages.",
        "positive": "Thermal induced monochromatic microwave generation in magnon-polariton: We propose thermal induced generation of monochromatic microwave radiation in\nmagnon-polariton. Mechanism of thermal to microwave energy transformation is\nbased on intrinsic energy loss compensation of coupled magnon and microwave\ncavity oscillators by thermal induced \"negative damping\". A singularity at an\nexceptional point is achieved when at the critical value of \"negative damping\"\nthe damping of the system is fully compensated. At the exceptional point, the\ninput energy is equally distributed between the magnon and photon subsystems of\nthe magnon-polariton. The efficiency of transformation of thermal energy into\nuseful microwave radiation is estimated to be as large as 17 percent due to\nmagnon-photon coupling mediated direct conversation of spin current into\nmicrowave photons."
    },
    {
        "anchor": "Nonradiative Recombination of Excitons in Carbon Nanotubes Mediated by\n  Free Charge Carriers: Free electrons or holes can mediate the nonradiative recombination of\nexcitons in carbon nanotubes. Kinematic constraints arising from the quasi\none-dimensional nature of excitons and charge carriers lead to a thermal\nactivation barrier for the process. However, a model calculation suggests that\nthe rate for recombination mediated by a free electron is the same order of\nmagnitude as that of two-exciton recombination. Small amounts of doping may\ncontribute to the short exciton lifetimes and low quantum yields observed in\ncarbon nanotubes.",
        "positive": "Influence of nano-mechanical properties on single electron tunneling: A\n  vibrating Single-Electron Transistor: We describe single electron tunneling through molecular structures under the\ninfluence of nano-mechanical excitations. We develop a full quantum mechanical\nmodel, which includes charging effects and dissipation, and apply it to the\nvibrating C$_{60}$ single electron transistor experiment by Park {\\em et al.}\n{[Nature {\\bf 407}, 57 (2000)].} We find good agreement and argue vibrations to\nbe essential to molecular electronic systems. We propose a mechanism to realize\nnegative differential conductance using local bosonic excitations."
    },
    {
        "anchor": "Effect of extended confinement on the structure of edge channels in the\n  quantum anomalous Hall effect: Quantum anomalous Hall (QAH) effect in the films with nontrivial band\nstructure accompanies the ferromagnetic transition in the system of magnetic\ndopants. Experimentally, the QAH transition manifests itself as a jump in the\ndependence of longitudinal resistivity on a weak external magnetic field.\nMicroscopically, this jump originates from the emergence of a chiral edge mode\non one side of the ferromagnetic transition. We study analytically the effect\nof an extended confinement on the structure of the edge modes. We employ the\nsimplest model of the extended confinement in the form of potential step next\nto the hard wall. It is shown that, unlike the conventional quantum Hall\neffect, where all edge channels are chiral, in QAH effect, a complex structure\nof the boundary leads to nonchiral edge modes which are present on both sides\nof the ferromagnetic transition. Wave functions of nonchiral modes are\ndifferent above and below the transition: on the \"topological\" side, where the\nchiral edge mode is supported, nonchiral modes are \"repelled\" from the\nboundary, i.e. they are much less localized than on the \"trivial\" side. Thus,\nthe disorder-induced scattering into these modes will boost the extension of\nthe chiral edge mode. The prime experimental manifestation of nonchiral modes\nis that, by contributing to longitudinal resistance, they smear the QAH\ntransition.",
        "positive": "Dephasing and the Orthogonality Catastrophe in Tunneling through a\n  Quantum Dot: the ``Which Path?'' Interferometer: The ``Which Path?'' interferometer consists of an Aharonov-Bohm ring with a\nquantum dot (QD) built in one of its arms, and an additional quantum point\ncontact (QPC) located close to the QD. The transmission coefficient of the QPC\ndepends on the charge state of the QD. Hence the point contact causes\ncontrollable dephasing of transport through the QD, and acts as a measurement\ndevice for which path an electron takes through the ring. We calculate the\nsuppression of the Aharonov-Bohm oscillations which is caused both by dephasing\nand by the orthogonality catastrophe, i.e., respectively, by real and virtual\nelectron-hole pair creation at the QPC."
    },
    {
        "anchor": "A site-controlled quantum dot system offering both high uniformity and\n  spectral purity: In this paper we report on the optical properties of site controlled InGaAs\ndots with GaAs barriers grown in pyramidal recesses by metalorganic vapour\nphase epitaxy. The inhomogeneous broadening of excitonic emission from an\nensemble of quantum dots is found to be unusually narrow, with a standard\ndeviation of 1.19 meV, and spectral purity of emission lines from individual\ndots is found to be very high (18-30 ueV), in contrast with other\nsite-controlled systems.",
        "positive": "Reply to \"Comment on 'Topological stability of the half-vortices in\n  spinor exciton-polariton condensates'\": In a recent work [H. Flayac, I.A. Shelykh, D.D. Solnyshkov and G. Malpuech,\nPhys. Rev. B 81, 045318 (2010)], we have analyzed the effect of the TE-TM\nsplitting on the stability of the exciton-polariton vortex states. We\nconsidered classical vortex solutions having cylindrical symmetry and we found\nthat the so-called half-vortex states [Yu. G. Rubo, Phys. Rev. Lett. 99, 106401\n(2007)] are not solutions of the stationary Gross-Pitaevskii equation. In their\nComment [M. Toledo Solano, Yu.G. Rubo, Phys. Rev. B 82, 127301 (2010)], M.\nToledo Solano and Yuri G. Rubo claim that this conclusion is misleading and\npretend to demonstrate the existence of static half-vortices in an\nexciton-polariton condensate in the presence of TE-TM splitting. In this reply\nwe explain why this assertion is not demonstrated satisfactorily."
    },
    {
        "anchor": "Counting statistics and super-Poissonian noise in a quantum dot: We present time-resolved measurements of electron transport through a quantum\ndot. The measurements were performed using a nearby quantum point contact as a\ncharge detector. The rates for tunneling through the two barriers connecting\nthe dot to source and drain contacts could be determined individually. In the\nhigh bias regime, the method was used to probe excited states of the dot.\nFurthermore, we have detected bunching of electrons, leading to\nsuper-Poissonian noise. We have used the framework of the full counting\nstatistics (FCS) to model the experimental data. The existence of\nsuper-Poissonian noise suggests a long relaxation time for the involved excited\nstate, which could be related to the spin relaxation time.",
        "positive": "Spin-dependent transport in a clean one-dimensional channel: A shoulder-like feature close to $(0.7\\times 2e^{2}/h)$, \"the 0.7 structure\"\nat zero magnetic field was observed in clean one-dimensional (1D) channels\n[K.J. Thomas et al., Phys. Rev. Lett. 77, 135 (1996)]. To provide further\nunderstanding of this structure, we have performed low-temperature measurements\nof a novel design of 1D channel with overlaying finger gates to study the 0.7\nstructure as a function of lateral confinement strength and potential profile.\nWe found that the structure persists when the lateral confinement strength is\nchanged by a factor of 2. We have also shown that the 0.7 structure present in\ntwo 1D channels in series behaves like a single 1D channel which shows the 0.7\nstructure, demonstrating that the 0.7 structure is not a transmission effect\nthrough a ballistic channel at zero in-plane magnetic field."
    },
    {
        "anchor": "Electronic states in quantum wires on the M\u00f6bius strip: In this work, we study the properties of an electron constrained on wires\nalong the M\\\"{o}bius strip. We considered wires around the strip and along the\ntransverse direction, across the width of the strip. For each direction, we\ninvestigate how the curvature modifies the electronic states and their\ncorresponding energy spectrum. At the center of the strip, the wires around the\nsurface form quantum rings whose spectrum depends on the strip radius $a$. For\nwires at the edge of the strip, the inner edge turns into the outer edge.\nAccordingly, the curvature yields localized states in the middle of the wire.\nAlong the strip width, the effective potential exhibits a parity symmetry\nbreaking leading to the localization of the bound state on one side of the\nstrip.",
        "positive": "Exact two-body quantum dynamics of an electron-hole pair in\n  semiconductor coupled quantum wells: a time-dependent approach: We simulate the time-dependent coherent dynamics of a spatially indirect\nexciton (an electron-hole pair with the two particles confined in different\nlayers) in a GaAs coupled quantum well system. We use a unitary wave-packet\npropagation method taking into account in full the four degrees of freedom of\nthe two particles in a two-dimensional system, including both the long-range\nCoulomb attraction and arbitrary two-dimensional electrostatic potentials\naffecting the electron and/or the hole separately. The method has been\nimplemented for massively parallel architectures to cope with the huge\nnumerical problem, showing good scaling properties and allowing evolution for\ntens of picoseconds. We have investigated both transient time phenomena and\nasymptotic time transmission and reflection coefficients for potential profiles\nconsisting of i) extended barriers and wells and ii) a single-slit geometry. We\nfound clear signatures of the internal two-body dynamics, with transient\nphenomena in the picosecond time-scale which might be revealed by optical\nspectroscopy. Exact results have been compared with mean-field approaches\nwhich, neglecting dynamical correlations by construction, turn out to be\ninadequate to describe the electron-hole pair evolution in realistic\nexperimental conditions."
    },
    {
        "anchor": "A perturbative approach to the polaron shift of excitons in transition\n  metal dichalcogeniedes: In this paper we study the phonon's effect on the position of the 1s\nexcitonic resonance of the fundamental absorption transition line in\ntwo-dimensional transition metal dichalcogenides. We apply our theory to\nWS$_{2}$a two-dimensional material where the shift in absorption peak position\nhas been measured as a function of temperature. The theory is composed of two\ningredients only: i) the effect of longitudinal optical phonons on the\nabsorption peak position, which we describe with second order perturbation\ntheory; ii) the effect of phonons on the value of the single particle energy\ngap, which we describe with the Huang Rhys model. Our results show an excellent\nagreement with the experimentally measured shift of the absorption peak with\nthe temperature.",
        "positive": "Intrinsic two-dimensional state on the pristine surface of tellurium: Using a tight-binding description, we show how the zero-dimensional state\nbound to the edge of a single one-dimensional helical chain of tellurium atoms\nevolves into two-dimensional states on the c-axis surface of the\nthree-dimensional trigonal bulk. We give an effective Hamiltonian description\nof its dispersion in k-space by exploiting confinement to a virtual bilayer,\nand elaborate on the diminished role of spin-orbit coupling. These\npreviously-unidentified intrinsic gap-penetrating surface bands were neglected\nin the interpretation of seminal experiments, where two-dimensional transport\nwas otherwise attributed to extrinsic accumulation layers."
    },
    {
        "anchor": "Local Friedel sum rule on graphs: We consider graphs made of one-dimensional wires connected at vertices and on\nwhich may live a scalar potential. We are interested in a scattering situation\nwhere the graph is connected to infinite leads. We investigate relations\nbetween the scattering matrix and the continuous part of the local density of\nstates, the injectivities, emissivities and partial local density of states.\nThose latter quantities can be obtained by attaching an extra lead at the point\nof interest and by investigating the transport in the limit of zero\ntransmission into the additional lead. In addition to the continuous part\nrelated to the scattering states, the spectrum of graphs may present a discrete\npart related to states that remain uncoupled to the external leads. The theory\nis illustrated with the help of a few simple examples.",
        "positive": "Quantifying the thermal stability in perpendicularly magnetized\n  ferromagnetic nanodisks with forward flux sampling: The thermal stability in nanostructured magnetic systems is an important\nissue for applications in information storage. From a theoretical and\nsimulation perspective, an accurate prediction of thermally-activated\ntransitions is a challenging problem because desired retention times are on the\norder of 10 years, while the characteristic time scale for precessional\nmagnetization dynamics is of the order of nanoseconds. Here, we present a\ntheoretical study of the thermal stability of magnetic elements in the form of\nperpendicularly-magnetized ferromagnetic disks using the forward flux sampling\nmethod, which is useful for simulating rare events. We demonstrate how rates of\nthermally-activated switching between the two uniformly-magnetized ``up'' and\n``down'' states, which occurs through domain wall nucleation and propagation,\nvary with the interfacial Dzyaloshinskii-Moriya interaction, which affect the\nenergy barrier separating these states. Moreover, we find that the average\nlifetimes differ by several orders of magnitude from estimates based on the\ncommonly assumed value of 1 GHz for the attempt frequency."
    },
    {
        "anchor": "Suppressed conductance in a metallic graphene nano-junction: The linear conductance spectrum of a metallic graphene junction formed by\ninterconnecting two gapless graphene nanoribbons is calculated. A strong\nconductance suppression appears in the vicinity of the Dirac point. We found\nthat such a conductance suppression arises from the antiresonance effect\nassociated with the edge state localized at the zigzag-edged shoulder of the\njunction. The conductance valley due to the antiresonance is rather robust in\nthe presence of the impurity and vacancy scattering. And the center of the\nconductance valley can be readily tuned by an electric field exerted on the\nwider nanoribbon.",
        "positive": "Stability of C20 fullerene chains: The stability of (C20)N chains with N = 3 - 7 is analyzed by numerical\nsimulation using a tight-binding potential and molecular dynamics. Various\nchannels of losing the cluster-chain structure of the (C20)N complexes are\nobserved, including the decay of C20 clusters, their coalescence, and the\nseparation of one C20 fullerene from the chain."
    },
    {
        "anchor": "Transport and localization of waves in one-dimensional disordered media:\n  Random phase approximation and beyond: We report a systematic and detailed numerical study of statistics of the\nreflection coefficient $(|R(L)|^2)$ and its associated phase ($\\theta$) for a\nplane wave reflected from a one-dimensional (1D) disordered medium beyond the\nrandom phase approximation (RPA) for Gaussian white-noise disorder. We solve\nnumerically the full Fokker-Planck (FP) equation for the probability\ndistribution in the ($|R(L)|^2,\\theta(L)$)-space for different lengths of the\nsample with different \"disorder strengths\". The statistical electronic\ntransport properties of 1D disordered conductors are calculated using the\nLandauer four-probe resistance formula and the FP equation. This constitutes a\ncomplete solution for the reflection statistics and many aspects of electron\ntransport in a 1D Gaussian white-noise potential. Our calculation shows the\ncontribution of the phase distribution to the different averages and its\neffects on the one-parameter scaling theory of localization.",
        "positive": "A corner reflector of graphene Dirac fermions as a phonon-scattering\n  sensor: Dirac fermion optics exploits the refraction of chiral fermions across\noptics-inspired Klein-tunneling barriers defined by high-transparency p-n\njunctions. We consider the corner reflector (CR) geometry introduced in optics\nor radars. We fabricate Dirac fermion CRs using bottom-gate-defined barriers in\nhBN-encapsulated graphene. By suppressing transmission upon multiple internal\nreflections, CRs are sensitive to minute phonon scattering rates. We report on\ndoping-independent CR transmission in quantitative agreement with a simple\nscattering model including thermal phonon scattering. As a new signature of\nCRs, we observe Fabry-P\\'erot oscillations at low temperature, consistent with\nsingle-path reflections. Finally, we demonstrate high-frequency operation which\npromotes CRs as fast phonon detectors. Our work establishes the relevance of\nDirac fermion optics in graphene and opens a route for its implementation in\ntopological Dirac matter."
    },
    {
        "anchor": "Distribution of an Ohmic current in the close vicinity of a quantum\n  point contact: We present the essential findings of the screening theory of the integer\nquantum Hall effect (IQHE) considering a quantum point contact (QPC). Our\napproach is to solve the Poisson and the Schroedinger equations\nself-consistently, taking into account electron interactions, within a Hartree\ntype approximation for a two dimensional electron gas (2DEG) subject to high\nperpendicular magnetic fields. The Coulomb interaction between the electrons\nseparates 2DEG into two co-existing regions, namely quasi-metallic compressible\nand quasi-insulating incompressible regions, which exhibit peculiar screening\nand transport properties. In the presence of an external current, we show that\nthis current is confined into the incompressible regions where the drift\nvelocity is finite. In particular, we investigate the distribution of these\nincompressible strips and their relation with the quantum Hall plateaus\nconsidering a quasi 1D constriction, i.e. a QPC.",
        "positive": "Mirage Andreev spectra generated by mesoscopic leads in nanowire quantum\n  dots: We study transport mediated by Andreev bound states formed in InSb nanowire\nquantum dots. Two kinds of superconducting source and drain contacts are used:\nepitaxial Al/InSb devices exhibit a doubling of tunneling resonances, while in\nNbTiN/InSb devices Andreev spectra of the dot appear to be replicated multiple\ntimes at increasing source-drain bias voltages. In both devices, a mirage of a\ncrowded spectrum is created. To describe the observations a model is developed\nthat combines the effects of a soft induced gap and of additional Andreev bound\nstates both in the quantum dot and in the finite regions of the nanowire\nadjacent to the quantum dot. Understanding of Andreev spectroscopy is important\nfor the correct interpretation of Majorana experiments done on the same\nstructures."
    },
    {
        "anchor": "Gas dependent hysteresis in MoS$_2$ field effect transistors: We study the effect of electric stress, gas pressure and gas type on the\nhysteresis in the transfer characteristics of monolayer molybdenum disulfide\n(MoS2) field effect transistors. The presence of defects and point vacancies in\nthe MoS2 crystal structure facilitates the adsorption of oxygen, nitrogen,\nhydrogen or methane, which strongly affect the transistor electrical\ncharacteristics. Although the gas adsorption does not modify the conduction\ntype, we demonstrate a correlation between hysteresis width and adsorption\nenergy onto the MoS2 surface. We show that hysteresis is controllable by\npressure and/or gas type. Hysteresis features two well-separated current\nlevels, especially when gases are stably adsorbed on the channel, which can be\nexploited in memory devices.",
        "positive": "Graphene under bichromatic driving: Commensurability and spatio-temporal\n  symmetries: We study the non-linear current response of a Dirac model that is coupled to\ntwo time-periodic electro-magnetic fields with different frequencies. We\ndistinguish between incommensurable and commensurable frequencies, the latter\ncharacterized by their ratio p/q with co-prime integers p and q. Coupling the\n(effective) two-level system to a dissipative bath ensures a well-defined\nlong-time solution for the reduced density operator and, thus, the current. We\nthen analyze the spatio-temporal symmetries that force certain current\ncomponents to vanish and close with conclusions for directed average currents."
    },
    {
        "anchor": "Model and performance evaluation of field-effect transistors based on\n  epitaxial graphene on SiC: In view of the appreciable semiconducting gap of 0.26 eV observed in recent\nexperiments, epitaxial graphene on a SiC substrate seems a promising channel\nmaterial for FETs. Indeed, it is two-dimensional - and therefore does not\nrequire prohibitive lithography - and exhibits a wider gap than other\nalternative options, such as bilayer graphene. Here we propose a model and\nassess the achievable performance of a nanoscale FET based on epitaxial\ngraphene on SiC, conducting an exploration of the design parameter space. We\nshow that the current can be modulated by 4 orders of magnitude; for digital\napplications an Ion /Ioff ratio of 50 and a subthreshold slope of 145 mV/decade\ncan be obtained with a supply voltage of 0.25 V. This represents a significant\nprogress towards solid-state integration of graphene electronics, but not yet\nsufficient for digital applications.",
        "positive": "Studies of FemIrn nano clusters using Density Functional Theory\n  Techniques: The structure, binding energy, magnetic moments and electronic structure of\nFemIrn clusters are investigated using state of the art density functional\ntheory techniques. Fully unconstrained structural relaxations are undertaken by\nconsidering all possible non equivalent cluster structures. The optimized\nclusters are all compact, indicating a clear tendency to maximize the number of\nnearest neighbour Fe-Ir pairs. The binding energy shows an increment with\ncluster size. All the clusters preserve ferromagnetic order after optimization.\nThe average magnetic moment generally shows an increase with Fe concentration.\nThe spin polarized density of states is largely dominated by the contribution\nof d orbitals. An important enhancement of the local Fe moments in an Ir rich\nenvironment is observed due to the charge transfer between Fe and Ir. On the\nother hand, the Ir moments are already large in the pure Ir clusters and does\nnot show significant enhancement with Fe doping. The HOMO-LUMO gaps show a\ngeneral reduction with alloying, indicating more metallicity for the doped\nclusters than the pure ones."
    },
    {
        "anchor": "Mesoscopic fluctuations in entanglement dynamics: Understanding fluctuation phenomena plays a dominant role in the development\nof many-body physics. The time evolution of entanglement is essential to a\nbroad range of subjects in many-body physics, ranging from exotic quantum\nmatter to quantum thermalization. Stemming from various dynamical processes of\ninformation, fluctuations in entanglement evolution differ conceptually from\nout-of-equilibrium fluctuations of traditional physical quantities. Their\nstudies remain elusive. Here we uncover an emergent random structure in the\nevolution of the many-body wavefunction in two classes of integrable -- either\ninteracting or noninteracting -- lattice models. It gives rise to\nout-of-equilibrium entanglement fluctuations which fall into the paradigm of\nmesoscopic fluctuations of wave interference origin. Specifically, the\nentanglement entropy variance obeys a universal scaling law, in each class, and\nthe full distribution displays a sub-Gaussian upper and a sub-Gamma lower tail.\nThese statistics are independent of both the system's microscopic details and\nthe choice of entanglement probes, and broaden the class of mesoscopic\nuniversalities. They have practical implications for controlling entanglement\nin mesoscopic devices.",
        "positive": "Ignition and Propagation of Magnetic Avalanches in Mn$_{12}$-Acetate:\n  the effect of quantum tunneling: Using a wire heater to ignite magnetic avalanches in fixed magnetic field\napplied along the easy axis of single crystals of the molecular magnet\nMn$_{12}$-acetate, we report fast local measurements of the temperature and\ntime-resolved measurements of the local magnetization as a function of magnetic\nfield. In addition to confirming maxima in the velocity of propagation, we find\nthat avalanches trigger at a threshold temperature which exhibits pronounced\nminima at resonant magnetic fields, demonstrating that thermally assisted\nquantum tunneling plays an important role in the ignition as well as the\npropagation of magnetic avalanches in molecular magnets."
    },
    {
        "anchor": "Ab initio calculations of indium arsenide in the wurtzite phase:\n  structural, electronic and optical properties: Most III-V semiconductors, which acquire the zinc-blende phase as bulk\nmaterials, adopt the metastable wurtzite phase when grown in the form of\nnanowires. These are new semiconductors with new optical properties, in\nparticular, a different electronic band gap when compared with that grown in\nthe zinc-blende phase. The electronic gap of wurtzite InAs at the Gamma-point\nof the Brillouin zone (E0 gap) has been recently measured, E0 = 0.46 eV at low\ntemperature. The electronic gap at the A point of the Brillouin zone\n(equivalent to the L point in the zinc-blende structure, E1) has also been\nobtained recently based on a resonant Raman scattering experiment. In this\nwork, we calculate the band structure of InAs in the zinc-blende and wurtzite\nphases, using the full potential linearized augmented plane wave method,\nincluding spin-orbit interaction. The electronic band gap has been improved\nthrough the modified Becke-Johnson exchange-correlation potential. Both the E0\nand E1 gaps agree very well with the experiment. From the calculations, a\ncrystal field splitting of 0.122 eV and a spin-orbit splitting of 0.312 eV (the\nexperimental value in zinc-blende InAs is 0.4 eV) has been obtained. Finally,\nwe calculate the dielectric function of InAs in both the zinc-blende and\nwurtzite phases and a comparative discussion is given.",
        "positive": "Nonlinear dynamics of topological ferromagnetic textures for frequency\n  multiplication: We propose that the non-linear radio-frequency dynamics and nanoscale size of\ntopological magnetic structures associated to their well-defined internal modes\nadvocate for their use as in-materio scalable frequency multipliers for\nspintronic systems. Frequency multipliers allow for frequency conversion\nbetween input and output frequencies, and thereby significantly increase the\nrange of controllably accessible frequencies. In particular, we explore the\nexcitation of eigenmodes of topological magnetic textures by fractions of the\ncorresponding eigenfrequencies. We show via micromagnetic simulations that\nlow-frequency perturbations to the system can efficiently excite bounded modes\nwith a higher amplitude. For example, we excited the eigenmodes of isolated\nferromagnetic skyrmions by applying half, a third and a quarter of the\ncorresponding eigenfrequency. We predict that the frequency multiplication via\nmagnetic structures is a general phenomenon which is independent of the\nparticular properties of the magnetic texture, and works also for magnetic\nvortices, droplets and other topological textures."
    },
    {
        "anchor": "Resonant tunneling through double-barrier structures on graphene: Quantum resonant tunneling behaviors of double-barrier structures on graphene\nare investigated under the tight-binding approximation. The Klein tunneling and\nresonant tunneling are demonstrated for the quasiparticles with energy close to\nthe Dirac points. The Klein tunneling vanishes by increasing the height of the\npotential barriers to more than 300 meV. The Dirac transport properties\ncontinuously change to the Schrodinger ones. It is found that the peaks of\nresonant tunneling approximate to the eigen-levels of graphene nanoribbons\nunder appropriate boundary conditions. A comparison between the zigzag- and\narmchair-edge barriers is given.",
        "positive": "Ultrafast dynamics of bright and dark excitons in monolayer WSe$_2$ and\n  heterobilayer WSe$_2$/MoS$_2$: The energy landscape of optical excitations in mono- and few-layer transition\nmetal dichalcogenides (TMDs) is dominated by optically bright and dark\nexcitons. These excitons can be fully localized within a single TMD layer, or\nthe electron- and the hole-component of the exciton can be charge-separated\nover multiple TMD layers. Such intra- or interlayer excitons have been\ncharacterized in detail using all-optical spectroscopies, and, more recently,\nphotoemission spectroscopy. In addition, there are so-called hybrid excitons\nwhose electron- and/or hole-component are delocalized over two or more TMD\nlayers, and therefore provide a promising pathway to mediate charge-transfer\nprocesses across the TMD interface. Hence, an in-situ characterization of their\nenergy landscape and dynamics is of vital interest. In this work, using\nfemtosecond momentum microscopy combined with many-particle modeling, we\nquantitatively compare the dynamics of momentum-indirect intralayer excitons in\nmonolayer WSe$_2$ with the dynamics of momentum-indirect hybrid excitons in\nheterobilayer WSe$_2$/MoS$_2$, and draw three key conclusions: First, we find\nthat the energy of hybrid excitons is reduced when compared to excitons with\npure intralayer character. Second, we show that the momentum-indirect\nintralayer and hybrid excitons are formed via exciton-phonon scattering from\noptically excited bright excitons. And third, we demonstrate that the\nefficiency for phonon absorption and emission processes in the mono- and the\nheterobilayer is strongly dependent on the energy alignment of the intralayer\nand hybrid excitons with respect to the optically excited bright exciton.\nOverall, our work provides microscopic insights into exciton dynamics in TMD\nmono- and bilayers."
    },
    {
        "anchor": "Gate-controlled non-volatile graphene-ferroelectric memory: In this letter, we demonstrate a non-volatile memory device in a graphene FET\nstructure using ferroelectric gating. The binary information, i.e. \"1\" and \"0\",\nis represented by the high and low resistance states of the graphene working\nchannels and is switched by controlling the polarization of the ferroelectric\nthin film using gate voltage sweep. A non-volatile resistance change exceeding\n200% is achieved in our graphene-ferroelectric hybrid devices. The experimental\nobservations are explained by the electrostatic doping of graphene by electric\ndipoles at the ferroelectric/graphene interface.",
        "positive": "Time domain measurement of phase noise in a spin torque oscillator: We measure oscillator phase from the zero crossings of the voltage vs. time\nwaveform of a spin torque nanocontact oscillating in a vortex mode. The power\nspectrum of the phase noise varies with Fourier frequency $f$ as $1/f^2$,\nconsistent with frequency fluctuations driven by a thermal source. The\nlinewidth implied by phase noise alone is about 70 % of that measured using a\nspectrum analyzer. A phase-locked loop reduces the phase noise for frequencies\nwithin its 3 MHz bandwidth."
    },
    {
        "anchor": "Elastic measurements of amorphous silicon films at mK temperatures: The low temperature properties of glass are distinct from those of crystals\ndue to the presence of poorly understood low-energy excitations. The tunneling\nmodel proposes that these are atoms tunneling between nearby equilibria,\nforming tunneling two level systems (TLSs). This model is rather successful,\nbut it does not explain the remarkably universal value of the mechanical\ndissipation $Q^{-1}$ near 1 kelvin. The only known exceptions to this\nuniversality are the $Q^{-1}$ of certain thin films of amorphous silicon,\ncarbon and germanium. Recently, it was found that $Q^{-1}$ of amorphous silicon\n(a-Si) films can be reduced by two orders of magnitude by increasing the\ntemperature of the substrate during deposition. According to the tunneling\nmodel, the reduction in $Q^{-1}$ at 1 kelvin implies a reduction in\n$P_{0}\\gamma ^{2}$, where $P_{0}$ is the density of TLSs and $\\gamma $ is their\ncoupling to phonons. In this preliminary report, we demonstrate elastic\nmeasurements of a-Si films down to 20 mK. This will allow us, in future work,\nto determine whether $P_{0}$ or $\\gamma $ is responsible for the reduction in\n$Q^{-1}$ with deposition temperature.",
        "positive": "Non-equilibrium charge noise and dephasing from a spin-incoherent\n  Luttinger liquid: We theoretically investigate the charge noise and dephasing in a metallic\ndevice in close proximity to a spin incoherent Luttinger liquid with a small\nbut finite current. The frequency dependence of the charge noise exhibits a\nloss of frequency peaks corresponding to the $2k_F$ part of the density\ncorrelations in the electron liquid when the temperature $T$ is increased from\nvalues below the magnetic exchange energy $J$ of the electron gas to values\nabove it. The dephasing rate in a nearby metallic nanostructure also shows a\ncross-over for $T \\sim J$ and may exhibit a non-monotonic temperature\ndependence. For a range of temperatures the dephasing rate {\\em decreases} with\nincreasing temperatures. The proposed experiments provide a convenient approach\nto probe the spin-incoherent Luttinger liquid and should be implementable in a\nwide variety of systems."
    },
    {
        "anchor": "Effect of magnetic field on a magnetic topological insulator film with\n  structural inversion asymmetry: The effect of magnetic field on an ultrathin magnetic topological insulator\nfilm with structural inversion asymmetry is investigated. We introduce the\nphase diagram, calculate the Landau-level spectrum analytically and simulate\nthe transport behavior in Landauer-B\\\"uttiker formalism. The quantum anomalous\nHall phase will survive increasing magnetic field. Due to the two spin\npolarized zero modes of Landau levels a nontrivial phase similar with quantum\nspin Hall effect can be induced by magnetic field which is protected by\nstructural inversion symmetry. Some exotic longitudinal and Hall resistance\nplateaus with fractional values are also found in a six terminal Hall bar,\narising from the coupling between edge states due to inverted energy band and\nLandau levels.",
        "positive": "Toward theory of quantum Hall effect in graphene: We analyze a gap equation for the propagator of Dirac quasiparticles and\nconclude that in graphene in a magnetic field, the order parameters connected\nwith the quantum Hall ferromagnetism dynamics and those connected with the\nmagnetic catalysis dynamics necessarily coexist (the latter have the form of\nDirac masses and correspond to excitonic condensates). This feature of graphene\ncould lead to important consequences, in particular, for the existence of\ngapless edge states. Solutions of the gap equation corresponding to recently\nexperimentally discovered novel plateaus in graphene in strong magnetic fields\nare described."
    },
    {
        "anchor": "Understanding the Missing Fractional Quantum Hall States in ZnO: We have analyzed the crucial role the Coulomb interaction strength plays on\nthe even and odd denominator fractional quantum Hall effects in a\ntwo-dimensional electron gas (2DEG) in the ZnO heterointerface. In this system,\nthe Landau level gaps are much smaller than those in conventional GaAs systems.\nThe Coulomb interaction is also very large compared to the Landau level gap\neven in very high magnetic fields. We therefore consider the influence of\nhigher Landau levels by considering the screened Coulomb potential in the\nrandom phase approximation. Interestingly, our exact diagonalization studies of\nthe collective modes with this screened potential successfully explain recent\nexperiments of even and odd denominator fractional quantum Hall effects, in\nparticular, the unexpected absence of the 5/2 state and the presence of 9/2\nstate in ZnO.",
        "positive": "Microwave-induced spin currents in ferromagnetic-insulator|normal-metal\n  bilayer system: A microwave technique is employed to simultaneously examine the spin pumping\nand the spin Seebeck effect processes in a YIG|Pt bilayer system. The\nexperimental results show that for these two processes, the spin current flows\nin opposite directions. The temporal dynamics of the longitudinal spin Seebeck\neffect exhibits that the effect depends on the diffusion of bulk\nthermal-magnons in the thermal gradient in the\nferromagnetic-insulator|normal-metal system."
    },
    {
        "anchor": "First-order correlation function of the stream of single-electron\n  wave-packets: The first-order correlation function, which is accessible experimentally,\ncontains all essential information about the state of the system of\nnon-interacting electrons. Here I discuss how this function can be used to\nanswer the question whether the state of a periodic stream of single-electron\nwave-packets is a multi-particle state or it is the product of single-particle\nstates. In the latter case the correlation function is expected to be\nfactorizable while in the former case it is not. As an example I consider a\ntrain of Lorentzian in shape single-electron excitations, levitons. I\ndemonstrate that the correlation function in time domain is factorizable or not\ndepending on whether the wave-packets are separated or overlapping. In\ncontrast, the correlation function in energy domain is always factorizable and\nthus cannot be used to distinguish single- and multi-particle states.",
        "positive": "Tunneling transport in NSN junctions made of Majorana nanowires across\n  the topological quantum phase transition: We theoretically consider transport properties of a normal metal (N)-\nsuperconducting semiconductor nanowire (S)-normal metal (N) structure (NSN) in\nthe context of the possible existence of Majorana bound states in disordered\nsemiconductor-superconductor hybrid systems in the presence of spin-orbit\ncoupling and Zeeman splitting induced by an external magnetic field. We study\nin details the transport signatures of the topological quantum phase transition\nas well as the existence of the Majorana bound states in the electrical\ntransport properties of the NSN structure. Our theory includes the realistic\nnonperturbative effects of disorder, which is detrimental to the topological\nphase (eventually suppressing the superconducting gap completely), and the\neffects of the tunneling barriers (or the transparency at the tunneling NS\ncontacts), which affect (and suppress) the zero bias conductance peak\nassociated with the zero energy Majorana bound states. We show that in the\npresence of generic disorder and barrier transparency the interpretation of the\nzero bias peak as being associated with the Majorana bound state is problematic\nsince the nonlocal correlations between the two NS contacts at two ends may not\nmanifest themselves in the tunneling conductance through the whole NSN\nstructure. We establish that a simple modification of the standard transport\nmeasurements using conductance differences (rather than the conductance itself\nas in a single NS junction) as the measured quantity can allow direct\nobservation of the nonlocal correlations inherent in the Majorana bound states\nand enables the mapping out of the topological phase diagram (even in the\npresence of considerable disorder) by precisely detecting the topological\nquantum phase transition point."
    },
    {
        "anchor": "Microscopic view on the ultrafast photoluminescence from photo-excited\n  graphene: We present a joint theory-experiment study on ultrafast photoluminescence\nfrom photoexcited graphene. Based on a microscopic theory, we reveal two\ndistinct mechanisms behind the occurring photoluminescence: Besides the\nwell-known incoherent contribution driven by non-equilibrium carrier\noccupations, we found a coherent part that spectrally shifts with the\nexcitation energy. In our experiments, we demonstrate for the first time the\npredicted appearance and spectral shift of the coherent photoluminescence.",
        "positive": "Unified theory of quantum phase transitions in quantum dots with gapped\n  host bands: We present a unified theory of quantum phase transitions for half-filled\nquantum dots (QDs) coupled to gapped host bands. We augment the bands by\nadditional weakly coupled metallic lead which allows us to analyze the system\nby using standard numerical renormalization group techniques. The ground state\nproperties of the systems without the additional metallic lead are then\nextrapolated in a controlled way from the broadened subgap spectral functions.\nWe show that a broad class of narrow-gap-semiconductor tunneling densities of\nstates (TDOSs) support the existence of two distinct phases known from their\nsuperconducting counterpart. Namely, $0$ phase which is marked by the singlet\nground state and the $\\pi$ phase regime with the doublet ground state. To keep\na close analogy with the superconducting case, we focus on the influence of\nparticle-hole asymmetry of the TDOS of the subgap spectral features.\nNevertheless, we also discus the possibility of inducing singlet-doublet\nquantum phase transitions in experimental setups by varying the filling of the\nQD. In addition, for gapped TDOS functions with smoothed gap edges, we\ndemonstrate that all subgap peaks may leak out of the gap into the continuous\npart of the spectrum, an effect which has no counterpart in the superconducting\nAnderson model."
    },
    {
        "anchor": "Local transport in a disorder-stabilized correlated insulating phase: We report the experimental realization of a correlated insulating phase in 2D\nGaAs/AlGaAs heterostructures at low electron densities in a limited window of\nbackground disorder. This has been achieved at mesoscopic length scales, where\nthe insulating phase is characterized by a universal hopping transport\nmechanism. Transport in this regime is determined only by the average electron\nseparation, independent of the topology of background disorder. We have\ndiscussed this observation in terms of a pinned electron solid ground state,\nstabilized by mutual interplay of disorder and Coulomb interaction.",
        "positive": "Optical Properties of Pure and Mixed Germanium and Silicon Quantum Dots: We study the optical properties of hydrogen passivated silicon, germanium and\nmixed Ge/Si core/shell quantum dots (QDs) using high accuracy Density\nFunctional Theory (DFT) and time-dependent DFT (TDFT). We employ the hybrid DFT\nfunctional of Becke, Lee, Yang and Parr (B3LYP) in combination with good\nquality basis sets. As we have shown in our previous work, this combination is\nan accurate and computationally efficient way for such calculations. The mixed\nquantum dots, as would be expected, are more versatile and offer more\npossibilities for band gap engineering, with gap values (electronic and\noptical) between those of the corresponding Si and Ge dots. Our results support\nthe quantum confinement theory for all three types of QDs."
    },
    {
        "anchor": "Towards sub-30nm Contacted Gate Pitch, Forked Contact and\n  Dynamically-Doped Nanosheets to Enhance Si and 2D Materials Device Scaling: We propose a novel Forked-Contacts, Dynamically-Doped Multigate transistor as\nultimate scaling booster for both Si and 2D materials in aggressively-scaled\nnanosheet devices. Using accurate dissipative DFT-NEGF atomistic-simulation\nfundamentals and cell layout extrinsics, we demonstrate superior and optimal\ndevice characteristics and invertor energy - delays down to sub-30-nm pitches,\ni.e., a 10 nm scaling boost compared to the nanosheet MOSFET references.",
        "positive": "Kohn-Luttinger superconductivity in graphene: We investigate the development of superconductivity in graphene when the\nFermi level becomes close to one of the Van Hove singularities of the electron\nsystem. The origin of the pairing instability lies in the strong anisotropy of\nthe e-e scattering at the Van Hove filling, which leads to a channel with\nattractive coupling when making the projection of the BCS vertex on the\nsymmetry modes with nontrivial angular dependence along the Fermi line. We show\nthat the scale of the superconducting instability may be pushed up to\ntemperatures larger than 10 K, depending on the ability to tune the system to\nthe proximity of the Van Hove singularity."
    },
    {
        "anchor": "Theory of magnetization precession induced by a picosecond strain pulse\n  in ferromagnetic semiconductor (Ga,Mn)As: A theoretical model of the coherent precession of magnetization excited by a\npicosecond acoustic pulse in a ferromagnetic semiconductor layer of (Ga,Mn)As\nis developed. The short strain pulse injected into the ferromagnetic layer\nmodifies the magnetocrystalline anisotropy resulting in a tilt of the\nequilibrium orientation of magnetization and subsequent magnetization\nprecession. We derive a quantitative model of this effect using the\nLandau-Lifshitz equation for the magnetization that is precessing in the\ntime-dependent effective magnetic field. After developing the general\nformalism, we then provide a numerical analysis for a certain structure and two\ntypical experimental geometries in which an external magnetic field is applied\neither along the hard or the easy magnetization axis. As a result we identify\nthree main factors, which determine the precession amplitude: the\nmagnetocrystalline anisotropy of the ferromagnetic layer, its thickness, and\nthe strain pulse parameters.",
        "positive": "Landauer and Thouless Conductance: a Band Random Matrix Approach: We numerically analyze the transmission through a thin disordered wire of\nfinite length attached to perfect leads, by making use of banded random\nHamiltonian matrices. We compare the Landauer and the Thouless conductances,\nand find that they are proportional to each other in the diffusive regime,\nwhile in the localized regime the Landauer conductance is approximately\nproportional to the square of the Thouless one. Fluctuations of the Landauer\nconductance were also numerically computed; they are shown to slowly approach\nthe theoretically predicted value."
    },
    {
        "anchor": "Heat transport through a Josephson junction: We discuss heat transport through a Josephson tunnel junction under various\nbias conditions. We first derive the formula for the cooling power of the\njunction valid for arbitrary time dependence of the Josephson phase. Combining\nit with the classical equation of motion for the phase, we find the time\naveraged cooling power as a function of bias current or bias voltage. We also\nfind the noise of the heat current and, more generally, the full counting\nstatistics of the heat transport through the junction. We separately consider\nthe metastable superconducting branch of the current-voltage characteristics\nallowing quantum fluctuations of the phase in this case. This regime is\nexperimentally attractive since the junction has low power dissipation, low\nimpedance and therefore may be used as a sensitive detector.",
        "positive": "Second-Order Topological Phases in Non-Hermitian Systems: A $d$-dimensional second-order topological insulator (SOTI) can host\ntopologically protected $(d - 2)$-dimensional gapless boundary modes. Here we\nshow that a 2D non-Hermitian SOTI can host zero-energy modes at its corners. In\ncontrast to the Hermitian case, these zero-energy modes can be localized only\nat one corner. A 3D non-Hermitian SOTI is shown to support second-order\nboundary modes, which are localized not along hinges but anomalously at a\ncorner. The usual bulk-corner (hinge) correspondence in the second-order 2D\n(3D) non-Hermitian system breaks down. The winding number (Chern number) based\non complex wavevectors is used to characterize the second-order topological\nphases in 2D (3D). A possible experimental situation with ultracold atoms is\nalso discussed. Our work lays the cornerstone for exploring higher-order\ntopological phenomena in non-Hermitian systems."
    },
    {
        "anchor": "Characterization of a Two-Photon Quantum Battery: Initial Conditions,\n  Stability and Work Extraction: We consider a quantum battery that is based on a two-level system coupled\nwith a cavity radiation by means of a two-photon interaction. Various figures\nof merit, such as stored energy, average charging power, energy fluctuations,\nand extractable work are investigated, considering, as possible initial\nconditions for the cavity, a Fock state, a coherent state, and a squeezed\nstate. We show that the first state leads to better performances for the\nbattery. However, a coherent state with the same average number of photons,\neven if it is affected by stronger fluctuations in the stored energy, results\nin quite interesting performance, in particular since it allows for almost\ncompletely extracting the stored energy as usable work at short enough times.",
        "positive": "Three terminal vibron coupled hybrid quantum dot thermoelectric\n  refrigeration: A three terminal nanoscale refrigeration concept based on a vibron-coupled\nquantum dot hybrid system coupled to two electronic reservoirs and a phonon\nbath is proposed and analyzed in detail. While investigating the non-trivial\nrole of electron-phonon interactions, we show that, although they are well\nknown to be detrimental from a general refrigeration perspective, can be\nengineered to favorably improve the trade-off between the cooling power (CP)\nand the coefficient-of-performance (COP). Furthermore, an additional\nimprovement in the trade-off can be facilitated by applying a high electronic\nthermal bias. However, the allowed maximum of the thermal bias being strongly\nlimited by the electron-phonon coupling, in turn, determines the lowest\nachievable temperature of the cooled body. It is further demonstrated that such\ninteractions drive a phonon flow between the dot and bath whose direction and\nmagnitude depend on the temperature difference between the dot and bath. To\njustify its impact in optimizing the peak CP and COP, we show that a weak\ncoupling with the bath is preferable when the phonons relax through it and a\nstrong coupling is suitable in the opposite case when the phonons are extracted\nfrom the bath. Finally, in studying the effect of asymmetry in electronic\ncouplings, we show that a stronger coupling is favorable with the contact whose\ntemperature is closer to that of the bath. Combining these aspects, we believe\nthat this study could offer important guidelines for a possible realization of\nmolecular and quantum dot thermoelectric refrigerator."
    },
    {
        "anchor": "Properties of magnetized Coulomb crystals of ions with polarizable\n  electron background: We have studied phonon and thermodynamic properties of a body-centered cubic\n(bcc) Coulomb crystal of ions with weakly polarized electron background in a\nuniform magnetic field ${\\bf B}$. At $B=0$ the difference between phonon\nmoments calculated using the Thomas-Fermi (TF) and random phase (RPA)\napproximations is always less than one percent and for description of phonon\nproperties of a crystal TF formalism was used. This formalism was successfully\napplied to investigate thermodynamic properties of magnetized Coulomb crystals.\nIt was shown that the influence of the polarization of the electron background\nis significant only at $\\kappa_{\\rm TF}a > 0.1$ and $T \\ll T_{\\rm\np}(1+h^2)^{-1/2}$, where $\\kappa_{\\rm TF}$ is the Thomas-Fermi wavenumber, $a$\nis the ion sphere radius, $T_{\\rm p}\\equiv\\hbar \\omega_{\\rm p}$ is the ion\nplasma temperature, $h\\equiv \\omega_B/\\omega_{\\rm p}$, $\\omega_B$ is the ion\ncyclotron frequency and $\\omega_{\\rm p}$ is the ion plasma frequency.",
        "positive": "Antisymmetric magnetoresistance and helical magnetic structure in\n  compensated Gd/Co multilayer: Using spin dependent specular and off-specular polarized neutron reflectivity\n(PNR), we report the observation of a twisted helical magnetic structure with\nplanar 2{\\pi} domain wall (DW) and highly correlated magnetic domains in a\nGd/Co multilayer. Specular PNR with polarization analysis reveals the formation\nof planar 2{\\pi}DWs below a compensation temperature (TComp), resulting to\npositive exchange bias in this system. Off-specular PNR with spin polarization\nshowed development of magnetic inhomogenities (increase in magnetic roughness)\nfor central part (thickness ~ 25-30 {\\AA}) of each Gd layer, where\nmagnetization is aligned perpendicular (in-plane) to an applied field. These\nmagnetic roughness are vertically correlated and results into Bragg sheet in\nspin flip channel of Off-specular PNR data, which is contributing towards an\nantisymmetric magnetoresistance at TComp in the system. The growth and\ntunability of highly correlated magnetic inhomogeneities (roughness) and domain\nstructure around TComp in combination of twisted helical magnetic structure\nwith planar 2{\\pi}DWs will be key for application in all-spin-based technology."
    },
    {
        "anchor": "Coupling an epitaxial quantum dot to a fiber-based external-mirror\n  microcavity: We report the coupling of individual InAs quantum dots (QDs) to an\nexternal-mirror microcavity. The external mirror is bonded to a fiber and\npositioned above a semiconductor sample consisting of a QD-containing GaAs\nlayer on top of a distributed Bragg reflector (DBR). This open cavity can be\nrapidly tuned with a piezoelectric actuator without negatively affecting the QD\nlinewidth. A mirror radius of curvature of 42 microns and a cavity length of 10\nmicrons enable good mode-matching and thus high collection efficiency directly\ninto the fiber. With an improved finesse this system may enter the strong\ncoupling regime.",
        "positive": "Chiral molecular films as electron polarizers and polarization\n  modulators: Recent experiments on electron scattering through molecular films have shown\nthat chiral molecules can be efficient sources of polarized electrons even in\nthe absence of heavy nuclei as source of a strong spin-orbit interaction. We\nshow that self-assembled monolayers (SAMs) of chiral molecules are strong\nelectron polarizers due to the high density effect of the monolayers and\nexplicitly compute the scattering amplitude off a helical molecular model of\ncarbon atoms. Longitudinal polarization is shown to be the signature of chiral\nscattering. For elastic scattering, we find that at least double scattering\nevents must take place for longitudinal polarization to arise. We predict\nenergy windows for strong polarization, determined by the energy dependences of\nspin-orbit strength and multiple scattering probability. An incoherent\nmechanism for polarization amplification is proposed, that increases the\npolarization linearly with the number of helix turns, consistent with recent\nexperiments on DNA SAMs."
    },
    {
        "anchor": "Phenomenological noise model for superconducting qubits: two-state\n  fluctuators and 1=f noise: We present a general phenomenological model for superconducting qubits\nsubject to noise produced by two-state fluctuators whose couplings to the qubit\nare all roughly the same. In flux qubit experiments where the working point can\nbe varied, it is possible to extract both the form of the noise spectrum and\nthe number of fluctuators. We find that the noise has a broad spectrum\nconsistent with 1=f noise and that the number of fluctuators with slow\nswitching rates is surprisingly small: less than 100. If the fluctuators are\ninterpreted as unpaired surface spins, then the size of their magnetic moments\nis surprisingly large.",
        "positive": "Optical diode based on exciton-polaritons: We propose theoretically an optical diode based on exciton-polaritons in\nsemiconductor microcavities. A flow of polaritons in the bistable regime is\nused to send signals through an asymmetric fixed potential that favours the\ntunneling of particles in one direction. Through dynamic modelling of the\ncoherent polariton field, we demonstrate the characteristics of an ideal diode,\nnamely that the forward signal is fully transmitted while the transmission in\nthe reverse direction tends to zero, without any additional external control.\nMoreover, the system proves to be robust to the presence of disorder, intrinsic\nto microcavities, and can function at gigahertz repetition rates."
    },
    {
        "anchor": "Disordered Si:P nanostructures as switches and wires for nanodevices: Atomically precise placement of dopants in Si permits creating substitutional\nP nanowires by design. High-resolution images show that these wires are few\natoms wide with some positioning disorder with respect to the substitutional Si\nstructure sites. Disorder is expected to lead to electronic localization in\none-dimensional (1D) - like structures. Experiments, however, report good\ntransport properties in quasi-1D P nanoribbons. We investigate theoretically\ntheir electronic properties using an effective single-particle approach based\non a linear combination of donor orbitals (LCDO), with a basis of six orbitals\nper donor site, thus keeping the ground state donor orbitals' oscillatory\nbehavior due to interference among the states at the Si conduction band minima.\nOur model for the P positioning errors accounts for the presently achievable\nplacement precision allowing to study the localization crossover. In addition,\nwe show that a gate-like potential may control its conductance and localization\nlength, suggesting the possible use of Si:P nanostructures as elements of\nquantum devices, such as nanoswitches and nanowires.",
        "positive": "Nonequilibrium mesoscopic Fermi reservoirs distributions and particle\n  current through a coherent quantum system: We study particle current and occupation distribution in a recently proposed\nmodel for coherent quantum transport. In this model a system connected to\nmesoscopic Fermi reservoirs (mesoreservoir) is driven out of equilibrium by the\naction of superreservoirs with prescribed temperatures and chemical potentials\ndescribed by a simple dissipative mechanism with the Lindblad equation. We\ncompare exact (numerical) results for the non-equilibrium steady state particle\ncurrent with theoretical expectations based on the Landauer formula and show\nthat the model reproduce the behavior of coherent quantum systems in the\nexpected parameter region. We also obtain the occupation distribution on the\nmesoreservoir in the non-equilibrium steady state and compare them with the\noccupation distribution on the leads in usual description of coherent quantum\ntransport."
    },
    {
        "anchor": "Spin orientation of two-dimensional electron gas under intraband optical\n  pumping: The theory of spin orientation of two-dimensional (2D) electron gas has been\ndeveloped for intrasubband indirect optical transitions. The monopolar optical\norientation of electrons in the conduction band is caused by the indirect\nscattering with virtual intermediate states in the valence band and allowance\nfor selection rules for interband transitions. The considered mechanism of\noptical orientation is shown to be in an inherent relation with the special\nElliot-Yafet mechanism of electron spin relaxation induced by virtual interband\nscattering.",
        "positive": "Fractional Quantum Hall States of the $\\mathcal{A}$ phase in the Second\n  Landau Level: A proposal of the existence of an {\\em Anomalous} phase ($\\mathcal{A}$ phase)\n[https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.131.056202 Das et\nal., Phys. Rev. Lett. 131, 056202 (2023)] at the experimental range of moderate\nLandau-level-mixing strength has recently been made for $5/2$ state. We here\nreport that the gapped $\\mathcal{A}$ phase is generic to the sequence of\nspin-polarized fractional quantum Hall states with filling fractions $\\nu =\nn/(nm-1)$ and $\\nu = 1-n/(nm-1)$, $(n \\geqslant 1,\\,m\\geqslant 3)$, that\nexhausts almost all the observed states and also predicts some states in the\nsecond Landau level for GaAs systems. Our proposed trial wavefunctions for all\nthese states have remarkably high overlaps with the corresponding exact ground\nstates and can support non-Abelian quasiparticle excitations with charge\n$e/[2(nm-1)]$. By analyzing edge modes, we predict experimentally verifiable\nthermal Hall conductance $2.5(\\pi^2 k_B^2T/3h)$ for all the states in these\nsequences."
    },
    {
        "anchor": "Dependence of transport on adatom location for armchair-edge graphene\n  nanoribbons: We study the transport property for armchair-edge graphene nanoribbons\n(AGNRs) with an adatom coupling to a semi-infinite quantum wire. Using the\nnonequilibrium Green's function approach with tight-binding approximation, we\ndemonstrate that the tunneling current through the system is sensitively\ndependent on both the AGNR width and adatom location. Interestingly, when the\nadatom locates onto a carbon atom in the 3$j$th chain from the edge of a\nmetallic AGNR, the system shows a transmission gap accompanied by a threshold\nvoltage in $I-V$ curve like a semiconducting AGNR. This effect may be useful in\nscanning tunneling microscopy experimental characterization on graphene\nsamples.",
        "positive": "Two-phase stretching of molecular chains: While stretching of most polymer chains leads to rather featureless\nforce-extension diagrams, some, notably DNA, exhibit non-trivial behavior with\na distinct plateau region. Here we propose a unified theory that connects\nforce-extension characteristics of the polymer chain with the convexity\nproperties of the extension energy profile of its individual monomer subunits.\nNamely, if the effective monomer deformation energy as a function of its\nextension has a non-convex (concave up) region, the stretched polymer chain\nseparates into two phases: the weakly and strongly stretched monomers.\nSimplified planar and 3D polymer models are used to illustrate the basic\nprinciples of the proposed model. Specifically, we show rigorously that when\nthe secondary structure of a polymer is mostly due to weak non-covalent\ninteractions, the stretching is two-phase, and the force-stretching diagram has\nthe characteristic plateau. We then use realistic coarse-grained models to\nconfirm the main findings and make direct connection to the microscopic\nstructure of the monomers. We demostrate in detail how the two-phase scenario\nis realized in the \\alpha-helix, and in DNA double helix. The predicted plateau\nparameters are consistent with single molecules experiments. Detailed analysis\nof DNA stretching demonstrates that breaking of Watson-Crick bonds is not\nnecessary for the existence of the plateau, although some of the bonds do break\nas the double-helix extends at room temperature. The main strengths of the\nproposed theory are its generality and direct microscopic connection."
    },
    {
        "anchor": "Robustness of topological corner modes against disorder and application\n  to acoustic networks: We study the two-dimensional extension of the Su-Schrieffer-Heeger model in\nits higher order topological insulator phase, which is known to host corner\nstates. Using the separability of the model into a product of one-dimensional\nSu-Schrieffer-Heeger chains, we analytically describe the eigen-modes, and\nspecifically the zero-energy level, which includes states localized in corners.\nWe then consider networks with disordered hopping coefficients that preserve\nthe chiral (sublattice) symmetry of the model. We show that the corner mode and\nits localization properties are robust against disorder if the hopping\ncoefficients have a vanishing flux on appropriately defined super plaquettes.\nWe then show how this model with disorder can be realised using an acoustic\nnetwork of air channels, and confirm the presence and robustness of corner\nmodes.",
        "positive": "Sub- to Super-Poissonian crossover of current noise in helical edge\n  states coupled to a spin impurity in a magnetic field: Edge states of two-dimensional topological insulators are helical and\nsingle-particle backscattering is prohibited by time-reversal symmetry. In this\nwork, we show that an isotropic exchange coupling of helical edge states (HES)\nto a spin 1/2 impurity subjected to a magnetic field results in characteristic\nbackscattering current noise (BCN) as a function of bias voltage and tilt angle\nbetween the direction of the magnetic field and the quantization axis of the\nHES. In particular, we find transitions from sub-Poissonian (antibunching) to\nsuper-Poissonian (bunching) behavior as a direct consequence of the helicity of\nthe edge state electrons. We use the method of full counting statistics within\na master equation approach treating the exchange coupling between the spin-1/2\nimpurity and the HES perturbatively. We express the BCN via coincidence\ncorrelation functions of scattering processes between the HES which gives a\nprecise interpretation of the Fano factor in terms of bunching and antibunching\nbehavior of electron jump events. We also investigate the effect of\nelectron-electron interactions in the HES in terms of the Tomonaga-Luttinger\nliquid theory."
    },
    {
        "anchor": "An effective theory of pulse propagation in a nonlinear and disordered\n  medium in two dimensions: We develop an effective theory of pulse propagation in a nonlinear {\\it and}\ndisordered medium. The theory is formulated in terms of a nonlinear diffusion\nequation. Despite its apparent simplicity this equation describes novel\nphenomena which we refer to as \"locked explosion\" and \"diffusive\" collapse. The\nequation can be applied to such distinct physical systems as laser beams\npropagating in disordered photonic crystals or Bose-Einstein condensates\nexpanding in a disordered environment.",
        "positive": "Dynamical Lamb effect versus dissipation in superconducting quantum\n  circuits: Superconducting circuits provide a new platform to study nonstationary cavity\nQED phenomena. An example of such a phenomenon is a dynamical Lamb effect which\nis a parametric excitation of an atom due to the nonadiabatic modulation of its\nLamb shift. This effect has been initially introduced for a natural atom in a\nvarying cavity, while we suggested its realization in a superconducting\nqubit-cavity system with dynamically tunable coupling. In the present paper, we\nstudy the interplay between the dynamical Lamb effect and the energy\ndissipation, which is unavoidable in realistic systems. We find that despite of\nnaive expectations this interplay can lead to unexpected dynamical regimes. One\nof the most striking results is that photon generation from vacuum can be\nstrongly enhanced due to the qubit relaxation, which opens a new channel for\nsuch a process. We also show that dissipation in the cavity can increase the\nqubit excited state population. Our results can be used for the experimental\nobservation and investigation of the dynamical Lamb effect and accompanying\nquantum effects."
    },
    {
        "anchor": "Strain driven monoclinic distortion of ultrathin CoO films in\n  CoO/Pt(001) and exchange-coupled CoO/PtFe/Pt(001) systems: The structure and strain of ultrathin CoO films grown on a Pt(001) substrate\nand on a ferromagnetic PtFe pseudomorphic layer on Pt(001) have been determined\nwith insitu and real time surface x-ray diffraction. The films grow epitaxially\non both surfaces with an in-plane hexagonal pattern that yields a pseudo-cubic\nCoO(111) surface. A refined x-ray diffraction analysis reveals a slight\nmonoclinic distortion at RT induced by the anisotropic stress at the interface.\nThe tetragonal contribution to the distortion results in a ratio c/a > 1,\nopposite to that found in the low temperature bulk CoO phase. This distortion\nleads to a stable Co2+ spin configuration within the plane of the film.",
        "positive": "Theory of spin blockade, charge ratchet effect, and thermoelectrical\n  behavior in serially coupled quantum-dot system: The charge transport of a serially coupled quantum dots (SCQD) connected to\nthe metallic electrodes is theoretically investigated in the Coulomb blockade\nregime. A closed-form expression for the tunneling current of SCQD in the\n{\\color{red} weak interdot hopping} limit is obtained by solving an extended\ntwo-site Hubbard model via the Green's function method. We use this expression\nto investigate spin current rectification, negative differential conductance,\nand coherent tunneling in the nonlinear response regime. The current\nrectification arising from the space symmetry breaking of SCQD is suppressed by\nincreasing temperature. The calculation of SCQD is extended to the case of\nmultiple parallel SCQDs for studying the charge ratchet effect and SCQD with\nmultiple levels. In the linear response regime, the functionalities of spin\nfilter and low-temperature current filter are demonstrated to coexist in this\nsystem. It is further demonstrated that two-electron spin singlet and triplet\nstates can be readily resolved from the measurement of Seebeck coefficient\nrather than that of electrical conductance."
    },
    {
        "anchor": "Antiferromagnetic coupling of the single-molecule magnet Mn12 to a\n  ferromagnetic substrate: We investigate magnetic coupling between a monolayer of prototype\nsingle-molecule magnets Mn12 and a ferromagnetic Ni(111) substrate through S,\nusing density-functional theory (DFT) and a DFT+U method. Our DFT and DFT+U\ncalculations show that the Mn12 molecules favor antiferromagnetic coupling to\nthe Ni substrate, and that they possess magnetic moments deviated from the\nmagnetic moments of isolated Mn12 molecules. We find that the magnetic easy\naxis of the Mn12 on Ni (whole system) is dictated by that of the Ni substrate.\nThe antiferromagnetic coupling is, dominantly, caused by superexchange\ninteractions between the magnetic moments of the Mn and the Ni substrate via\nthe S, C, and O anions. Our findings can be observed from x-ray magnetic\ncircular dichroism or scanning tunneling microscopy.",
        "positive": "Electron transport through a quantum wire coupled with a mesoscopic ring: Electronic transport through a quantum wire sandwiched between two metallic\nelectrodes and coupled to a quantum ring, threaded by a magnetic flux $\\phi$,\nis studied. An analytic approach for the electron transport through the bridge\nsystem is presented based on the tight-binding model. The transport properties\nare discussed in three aspects: (a) presence of an external magnetic filed, (b)\nstrength of the wire to electrode coupling, and (c) presence of in-plane\nelectric field."
    },
    {
        "anchor": "Edge states in proximitized graphene ribbons and flakes in a\n  perpendicular magnetic field: emergence of lone pseudohelical pairs and pure\n  spin-current states: We investigate the formation of edge states in graphene ribbons and flakes\nwith proximity induced valley-Zeeman and Rashba spin-orbit couplings in the\npresence of a perpendicular magnetic field $B$. Two types of edges states\nappear in the spin-orbit gap at the Fermi level at zero field: strongly\nlocalized pseudohelical (intervalley) states and weakly localized intravalley\nstates. We show that if the magnetic field is stronger than a crossover field\n$B_c$, which is a few mT for realistic systems such as graphene/WSe$_2$, only\nthe pseudohelical edge states remain in zigzag graphene ribbons; the\nintravalley states disappear. The crossover is directly related to the closing\nand reopening of the bulk gap formed between nonzero Landau levels. Remarkably,\nin finite flakes the pseudohelical states undergo perfect reflection at the\narmchair edges if $B > B_c$, forming standing waves at the zigzag edges. These\nstanding waves comprise two counterpropagating pseudohelical states, so while\nthey carry no charge current, they do carry (pure) spin current.",
        "positive": "Universality and thermoelectric transport properties of quantum dot\n  systems: We discuss the temperature-dependent thermoelectric transport properties of\nsemiconductor nanostructures comprising a quantum dot coupled to quantum wires:\nthe thermal dependence of the electrical conductance, thermal conductance, and\nthermopower. We explore the universality of the thermoelectric properties in\nthe temperature range associated with the Kondo crossover. In this thermal\nrange, general arguments indicate that any equilibrium property's temperature\ndependence should be a universal function of the ratio $T^{*}=T/T_{K}$, where\n$T_{K}$ is the Kondo temperature. Considering the particle-hole symmetric,\nspin-degenerate Anderson model, the zero-bias electrical conductance has\nalready been shown to map linearly onto a universal conductance through a\nquantum dot embedded or side-coupled to a quantum wire. Employing rigorous\nrenormalization-group arguments, we calculate universal thermoelectric\ntransport coefficients that allow us to extend this result to the thermopower\nand the thermal conductance. We present numerical renormalization-group results\nto illustrate the physics in our findings. Applying the universal\nthermoelectric coefficients to recent experimental results of the electrical\nconductance and thermo-voltages versus $V_{gate}$, at different temperatures in\nthe Kondo regime, we calculate all the thermoelectric properties and obtain\nsimple analytical fitting functions that can be used to predict the\nexperimental results of these properties. However, we cannot check all of them,\ndue to the lack of available experimental results over a broad temperature\nrange."
    },
    {
        "anchor": "Aharonov-Bohm effect and giant magnetoresistance in graphene nanoribbon\n  rings: We report a numerical study on Aharonov-Bohm (AB) effect and giant\nmagnetoresistance in rectangular rings made of graphene nanoribbons (GNRs). We\nshow that in low energy regime where only the first subband of contact GNRs\ncontributes to the transport, the transmission probability can be strongly\nmodulated, i.e., almost fully suppressed, when tuning a perpendicular magnetic\nfield. On this basis, strong AB oscillations with giant negative\nmagnetoresistance can be achieved at room temperature. The magnetoresistance\nreaches thousands % in perfect GNR rings and a few hundred % with edge\ndisordered GNRs. The design rules to observe such strong effects are also\ndiscussed. Our study hence provides guidelines for further investigations of\nthe AB interference and to obtain high magnetoresistance in graphene devices.",
        "positive": "Spatial mapping of the Dirac point in monolayer and bilayer graphene: We have mapped the Dirac point in exfoliated monolayer and bilayer graphene\nusing spatially resolved scanning tunneling spectroscopy (STS) measurements at\nlow temperature. The Dirac point shifts in energy at different locations in\ngraphene. However, a cross correlation with the topography shows no correlation\nindicating that topographic features such as ripples are not the primary source\nof the variation. Rather, we attribute the shift of the Dirac point to random\ncharged impurities located near the graphene. Our findings emphasize the need\nto advance exfoliated graphene sample preparation to minimize the effect of\nimpurities."
    },
    {
        "anchor": "Classification of stable Dirac and Weyl semimetals with reflection and\n  rotational symmetry: Three dimensional (3D) Dirac semimetal is a novel state of quantum matter,\ncharacterized by the gapless bulk four-fold degeneracy near Fermi energy. Soon\nafter its discovery, the classification of stable 3D Dirac semimetals with\ninversion and rotational symmetry have been studied. However, only ten out of\nthirty-two point groups have both inversion and rotational symmetry, and we\nneed a more complete classification of stable 3D Dirac semimetals. Here we\nclassify stable 3D Dirac semimetals with reflection symmetry and rotational\nsymmetry in the presence of time reversal symmetry, which belong to seventeen\ndifferent point groups. These systems include the systems preserving inversion\nsymmetry except $\\mathrm{C_{3i}}$. They have two classes of reflection\nsymmetry, with the mirror plane parallel to rotation axis and the mirror plane\nperpendicular to rotation axis. In both cases two types of Dirac semimetals are\ndetermined by four different reflection symmetries. The first type of Dirac\nsemimetals will appear through accidental band crossing (ABC). The second type\nof Dirac semimetals have a Dirac point at a time reversal invariant momentum\n(TBC). We show that in both mirror parallel and perpendicular cases, $C_{2,3}$\nsymmetry can only protect stable Dirac points via TBC, while $C_{4,6}$ symmetry\ncan have stable Dirac points as ABC or TBC. We further discuss that Weyl line\nnodes and Dirac semimetal can exist in Brillouin zone at the same time using\n$\\mathrm{C_{4v}}$ symmetry as an example. Finally we classify Dirac line nodes\nand Weyl line nodes to show in which types of mirror plane they can exist.",
        "positive": "Thermally activated magnetization reversal in a FeCoB nanomagnet.\n  High-precision measurement method of coercive field, delta, retention time\n  and size of nucleation domain: Features of thermally-activated magnetization switching have been studied in\na FeCoB nanomagnet using the N\\'eel model. A method of a high-precision\nmeasurement of the coercive field, retention time, {\\Delta} and the size of the\nswitching nucleation domain has been proposed and experimentally demonstrated\nusing a Hall-probe setup. A high measurement precision, repeatability and\nreliability are the features of the proposed method. The dependency of the\nparameters of thermally-activated magnetization switching on the gate voltage\nand the bias current were studied."
    },
    {
        "anchor": "Electrons on rotationally symmetric nanoparticles under a strong\n  magnetic field: The energy spectrum of an electron confined to an arbitrary surface of\nrevolution in an external magnetic field, parallel to the symmetry axis, is\nstudied analitycally and numerically. The problem is reduced via conformal\nmapping to one on the surface of a sphere. The case of a spheroid is considered\nin details, and the dependence on parameters is discussed. In the high magnetic\nfield limit a regular structure in the energy spectrum, resembling the Landau\nlevels, is obtained. Level statistics is discussed.",
        "positive": "Effective quasiparticle approach for a Cavity-QDots System: In this work, we present a quasiparticle strategy to study the Hamiltonian\ndescription of the stationary states for two quantum dots--cavity system. We\nconsider three different effective schemes of quasiparticles that give an\nin-depth insight into the physics involved in the Hamiltonian eigenstates for\nparameters that optimize or minimize the energy gap condition. We analyze\nfeatures of quantum measures like fractional composition, linear entropy, and\nconcurrence to observe which one description gives the complete physical\ninformation. Our findings show that a polaritonic---light-matter\nquasiparticle---approach catch better the physics contained in the whole\nregimes considered."
    },
    {
        "anchor": "Cantor Spectra for Double Exchange Model: We numerically study energy spectra and localization properties of the double\nexchange model at irrational filling factor. To obtain variational ground\nstate, we use a mumerical technique in momentum space by ``embedded'' boundary\ncondition which has no finite size effect a priori. Although the Hamiltonian\nhas translation invariance, the ground state spontaneously exhibits a\nself-similarity. Scaling and multi-fractal analysis for the wave functions are\nperformed and the scaling indices $\\alpha$'s are obtained. The energy spectrum\nis found to be a singular continuous, so-called the Cantor set with zero\nLebesque measure.",
        "positive": "Coupling of MoS$_2$ Excitons with Lattice Phonons and Cavity Vibrational\n  Phonons in Hybrid Nanobeam Cavities: We report resonant Raman spectroscopy of neutral excitons X$^0$ and\nintravalley trions X$^-$ in hBN-encapsulated MoS$_2$ monolayer embedded in a\nnanobeam cavity. By temperature tuning the detuning between Raman modes of\nMoS$_2$ lattice phonons and X$^0$/X$^-$ emission peaks, we probe the mutual\ncoupling of excitons, lattice phonons and cavity vibrational phonons. We\nobserve an enhancement of X$^0$-induced Raman scattering and a suppression for\nX$^-$-induced, and explain our findings as arising from the tripartite\nexciton-phonon-phonon coupling. The cavity vibrational phonons provide\nintermediate replica states of X$^0$ for resonance conditions in the scattering\nof lattice phonons, thus enhancing the Raman intensity. In contrast, the\ntripartite coupling involving X$^-$ is found to be much weaker, an observation\nexplained by the geometry-dependent polarity of the electron and hole\ndeformation potentials. Our results indicate that phononic hybridization\nbetween lattice and nanomechanical modes plays a key role in the excitonic\nphotophysics and light-matter interaction in 2D-material nanophotonic systems."
    },
    {
        "anchor": "Topological Phononic Crystals with One-Way Elastic Edge Waves: We report a new type of phononic crystals with topologically non-trivial\nbandgaps for both longitudinal and transverse polarizations, resulting in\nprotected one-way elastic edge waves. In our design, gyroscopic inertial\neffects are used to break the time-reversal symmetry and realize the phononic\nanalogue of the electronic quantum Hall effect. We investigate the response of\nboth hexagonal and square gyroscopic lattices and observe bulk Chern number of\n1 and 2, indicating that these structures support single and multi-mode edge\nelastic waves immune to back-scattering. These robust one-way phononic\nwaveguides could potentially lead to the design of a novel class of surface\nwave devices that are widely used in electronics, telecommunication and\nacoustic imaging.",
        "positive": "Coulomb-Blockade Oscillations in Semiconductor Nanostructures: I. Introduction (Preface, Basic properties of semiconductor nanostructures).\n  II. Theory of Coulomb-blockade oscillations (Periodicity of the oscillations,\nAmplitude and lineshape).\n  III. Experiments on Coulomb-blockade oscillations (Quantum dots, Disordered\nquantum wires, Relation to earlier work on disordered quantum wires).\n  IV. Quantum Hall effect regime (The Aharonov-Bohm effect in a quantum dot,\nCoulomb blockade of the Aharonov-Bohm effect, Experiments on quantum dots,\nExperiments on disordered quantum wires)."
    },
    {
        "anchor": "On the chemical bonding effects in the Raman response: Benzenethiol\n  adsorbed on silver clusters: We study the effects of chemical bonding on Raman scattering from\nbenzenethiol chemisorbed on silver clusters using time-dependent density\nfunctional theory (TDDFT). Raman scattering cross sections are computed using a\nformalism that employs analytical derivatives of frequency-dependent electronic\npolarizabilities, which treats both off-resonant and resonant enhancement\nwithin the same scheme. In the off-resonant regime, Raman scattering into\nmolecular vibrational modes is enhanced by one order of magnitude and shows\npronounced dependence on the orientation and the local symmetry of the\nmolecule. Additional strong enhancement of the order of $10^2$ arises from\nresonant transitions to mixed metal--molecular electronic states. The Raman\nenhancement is analyzed using Raman excitation profiles (REPs) for the range of\nexcitation energies $1.6-3.0$ eV, in which isolated benzenethiol does not have\nelectronic transitions. The computed vibrational frequency shifts and relative\nRaman scattering cross sections of the metal--molecular complexes are in good\nagreement with experimental data on surface enhanced Raman scattering (SERS)\nfor benzenethiol adsorbed on silver surfaces. Characterization and\nunderstanding of these effects, associated with chemical enhancement mechanism,\nmay be used to improve the detection sensitivity in molecular Raman scattering.",
        "positive": "Dissipationless mechanism of skyrmion Hall current in double-exchange\n  ferromagnets: We revisit a theory of skyrmion transport in ferromagnets. On a basis of an\neffective U(1) gauge theory for spin-chirality fluctuations in double-exchange\nferromagnets, we derive an expression for the velocity of a skyrmion core\ndriven by the dc electric field. We find that mutual feedback effects between\nconduction electrons and localized spins give rise to Chern-Simons terms,\nsuggesting a dissipationless mechanism for the skyrmion Hall current. A\nconventional description of the current-induced skyrmion motion, appearing\nthrough the spin transfer torque and scattering events, is reproduced in a\ncertain limit of our description, where the Chern-Simons terms are not fully\nincorporated. Our theory is applicable to not only metallic but also insulating\nsystems, where the purely topological and dissipationless skyrmion Hall current\ncan be induced in the presence of an energy gap."
    },
    {
        "anchor": "Altermagnetism: spin-momentum locked phase protected by non-relativistic\n  symmetries: The search for novel magnetic quantum phases, phenomena and functional\nmaterials has been guided by relativistic magnetic-symmetry groups in coupled\nspin and real space from the dawn of the field in 1950s to the modern era of\ntopological matter. However, the magnetic groups cannot disentangle\nnon-relativistic phases and effects, such as the recently reported\nunconventional spin physics in collinear antiferromagnets from the typically\nweak relativistic spin-orbit coupling phenomena. Here we discover that more\ngeneral spin symmetries in decoupled spin and crystal space categorize\nnon-relativistic collinear magnetism in three phases: conventional ferromagnets\nand antiferromagnets, and a third distinct phase combining zero net\nmagnetization with an alternating spin-momentum locking in energy bands, which\nwe dub \"altermagnetic\". For this third basic magnetic phase, which is omitted\nby the relativistic magnetic groups, we develop a spin-group theory describing\nsix characteristic types of the altermagnetic spin-momentum locking. We\ndemonstrate an extraordinary spin-splitting mechanism in altermagnetic bands\noriginating from a local electric crystal field, which contrasts with the\nconventional magnetic or relativistic splitting by global magnetization or\ninversion asymmetry. Based on first-principles calculations, we identify\naltermagnetic candidates ranging from insulators and metals to a parent crystal\nof cuprate superconductor. Our results underpin emerging research of quantum\nphases and spintronics in high-temperature magnets with light elements,\nvanishing net magnetization, and strong spin-coherence.",
        "positive": "Coulomb electron drag mechanism of terahertz plasma instability in\n  n+-i-n-n+ graphene FETs with ballistic injection: We predict the self-excitation of terahertz (THz) oscillations due to the\nplasma instability in the lateral n+-i-n-n+$ graphene field-effect transistors\n(G-FET). The instability is associated with the Coulomb drag of the\nquasi-equilibrium electrons in the gated channel by the injected ballistic\nelectrons resulting in a positive feedback between the amplified dragged\nelectrons current and the injected current. The plasma excitations arise when\nthe drag effect is sufficiently strong. The drag efficiency and the plasma\nfrequency are determined by the quasi-equilibrium electrons Fermi energy (i.e.,\nby their density). The conditions of the terahertz plasma oscillation\nself-excitation can be realized in the G-FETs with realistic structural\nparameters at room temperature enabling the potential G-FET-based radiation\nsources for the THz applications."
    },
    {
        "anchor": "Conductivity of two-dimensional narrow gap semiconductors subjected to\n  strong Coulomb disorder: In the ideal disorder-free situation, a two-dimensional band gap insulator\nhas an activation energy for conductivity equal to half the band gap $\\Delta$.\nBut transport experiments usually exhibit a much smaller activation energy at\nlow temperature, and the relation between this activation energy and $\\Delta$\nis unclear. Here we consider the temperature-dependent conductivity of a\ntwo-dimensional insulator on a substrate containing Coulomb impurities, with\nrandom potential amplitude $\\Gamma \\gg \\Delta$. We show that the conductivity\ngenerically exhibits three regimes of conductivity, and only the highest\ntemperature regime exhibits an activation energy that reflects the band gap. At\nlower temperatures, the conduction proceeds through activated hopping or\nEfros-Shklovskii variable-range hopping between electron and hole puddles\ncreated by the disorder. We show that the activation energy and characteristic\ntemperature associated with these processes steeply collapse near a critical\nimpurity concentration. Larger concentrations lead to an exponentially small\nactivation energy and exponentially long localization length, which in\nmesoscopic samples can appear as a disorder-induced insulator-to-metal\ntransition. We also arrive at a similar steep disorder driven insulator-metal\ntransition in thin films of three-dimensional topological insulators with large\ndielectric constant, for which Coulomb impurities inside the film create a\nlarge disorder potential due to confinement of their electric field inside the\nfilm.",
        "positive": "Tunable anisotropic behaviors in phosphorene under periodic potentials\n  in arbitrary directions: We investigate theoretically the anisotropic electronic and optical behaviors\nof a monolayer black phosphorus (phosphorene) modulated by periodic potential\nsuperlattices in arbitrary directions. We demonstrate that different strength\nand orientation of the phosphorene potential superlattice can give rise to\ndistinct energy spectra, i.e., tuning the intrinsic electronic anisotropy.\nAccordingly, the anisotropic effective mass, and optical absorption modulated\nby superlattice strength and orientation are addressed systematically. This\nfeature enables tuning capability more than one order of magnitude in the\noptical absorption spectrum. Our findings should be useful in building\nphosphorene optical and (opto)electronic devices by applying external potential\nsuperlattice."
    },
    {
        "anchor": "Optical polarization of localized hole spins in p-doped quantum wells: The initialization of spin polarization in localized hole states is\ninvestigated using time-resolved Kerr rotation. We find that the sign of the\npolarization depends on the magnetic field, and the power and the wavelength of\nthe circularly polarized pump pulse. An analysis of the spin dynamics and the\nspin-initialization process shows that two mechanisms are responsible for spin\npolarization with opposite sign: The difference of the g factor between the\nlocalized holes and the trions, as well as the capturing process of dark\nexcitons by the localized hole states.",
        "positive": "Random Telegraph Signal in a Metallic Double-Dot System: In this work, we investigate the dynamics of a single electron surface trap,\nembedded in a self-assembly metallic double-dot system. The charging and\ndischarging of the trap by a single electron is manifested as a random\ntelegraph signal of the current through the double-dot device. We find that we\ncan control the duration time that an electron resides in the trap through the\ncurrent that flows in the device, between fractions of a second to more than an\nhour. We suggest that the observed switching is the electrical manifestation of\nthe optical blinking phenomenon, commonly observed in semiconductor quantum\ndots."
    },
    {
        "anchor": "Optimizing the Cooper pair splitting efficiency in a Y-shaped junction: This letter is devoted to the optimization of the Cooper pair splitting\nefficiency in a Y-shaped junction. The latter consists of two quantum dots, one\nsuperconducting and two normal leads. We tailor the bias in the two normal\nleads such that the Cooper pairs leaving the superconductor are split up\nresulting in entangled electrons, one on each quantum dot. We are able to\nachieve a splitting efficiency of more than 99% which is significantly better\nthan the efficiencies obtained in experiments so far.",
        "positive": "Quantum dot spin qubits in Silicon: Multivalley physics: Research on Si quantum dot spin qubits is motivated by the long spin\ncoherence times measured in Si, yet the orbital spectrum of Si dots is\nincreased as a result of the valley degree of freedom. The valley degeneracy\nmay be lifted by the interface potential, which gives rise to a valley-orbit\ncoupling, but the latter depends on the detailed structure of the interface and\nis generally unknown a priori. These facts motivate us to provide an extensive\nstudy of spin qubits in Si double quantum dots, accounting fully for the valley\ndegree of freedom and assuming no prior knowledge of the valley-orbit coupling.\nFor single-spin qubits we analyze the spectrum of a multivalley double quantum\ndot, discuss the initialization of one qubit, identify the conditions for the\nlowest energy two-electron states to be a singlet and a triplet well separated\nfrom other states, and determine analytical expressions for the exchange\nsplitting. For singlet-triplet qubits we analyze the single-dot spectrum and\ninitialization process, the double-dot spectrum, singlet-triplet mixing in an\ninhomogeneous magnetic field and the peculiarities of spin blockade in\nmultivalley qubits. We review briefly the hyperfine interaction in Si and\ndiscuss its role in spin blockade in natural Si, including intravalley and\nintervalley effects. We study the evolution of the double-dot spectrum as a\nfunction of magnetic field. We address briefly the situation in which the\nvalley-orbit coupling is different in each dot due to interface roughness. We\npropose a new experiment for measuring the valley splitting in a single quantum\ndot. We discuss the possibility of devising other types of qubits in Si QDs,\nand the size of the intervaley coupling due to the Coulomb interaction."
    },
    {
        "anchor": "Density Functional Theory of Multicomponent Quantum Dots: Quantum dots with conduction electrons or holes originating from several\nbands are considered. We assume the particles are confined in a harmonic\npotential and assume the electrons (or holes) belonging to different bands to\nbe different types of fermions with isotropic effective masses. The density\nfunctional method with the local density approximation is used. The increased\nnumber of internal (Kohn-Sham) states leads to a generalisation of Hund's first\nrule at high densities. At low densitites the formation of Wigner molecules is\nfavored by the increased internal freedom.",
        "positive": "Edge states interferometry and spin rotations in zigzag graphene\n  nanoribbons: An interesting property of zigzag graphene nanoribbons is the presence of\nedge states which are extended along its borders but localized in the\ntransverse direction. We show that because of this property, electron transport\nthrough an externally induced potential well displays two-paths-interference\noscillations when subject either to a magnetic or a transverse electric field.\nThis effect does not require the existence of an actual `hole' in the\nnanoribbon's geometry. Moreover, since edge states are spin polarized, having\nopposite polarization on opposite sides, such interference effect can be used\nto rotate the spin of the incident carriers in a controlled way."
    },
    {
        "anchor": "Multivalley two-dimensional electron system in an AlAs quantum well with\n  mobility exceeding $2\\times10^6$ cm$^{2}$V$^{-1}$s$^{-1}$: Degenerate conduction-band minima, or `valleys', in materials such as Si,\nAlAs, graphene, and MoS$_2$ allow them to host two-dimensional electron systems\n(2DESs) that can access a valley degree of freedom. These multivalley 2DESs\npresent exciting opportunities for both pragmatic and fundamental research\nalike because not only are they a platform for valleytronic devices, but they\nalso provide a tool to tune and investigate the properties of complex many-body\nground states. Here, we report ultra-high quality, modulation doped AlAs\nquantum wells containing 2DESs that occupy two anisotropic valleys and have\nelectron mobilities peaking at $2.4\\times10^6$ cm$^{2}$V$^{-1}$s$^{-1}$ at a\ndensity of $2.2\\times10^{11}$ cm$^{-2}$. This is more than an order of\nmagnitude improvement in mobility over previous results. The unprecedented\nquality of our samples is demonstrated by magneto-transport data that show\nhigh-order fractional quantum Hall minima up to the Landau level filling\n$\\nu=8/17$, and even the elusive $\\nu=1/5$ quantum Hall state.",
        "positive": "From Birefringent Electrons to a Marginal or Non-Fermi Liquid of\n  Relativistic Spin-1/2 Fermions: An Emergent Superuniversality: We present the quantum critical theory of an interacting nodal Fermi-liquid\nof quasi-relativisitc pseudo-spin-3/2 fermions that have a non-interacting\nbirefringent spectrum with two distinct Fermi velocities. When such\nquasiparticles interact with gapless bosonic degrees of freedom that mediate\neither the long-range Coulomb interaction or its short range component\n(responsible for spontaneous symmetry breaking), in the deep infrared or\nquantum critical regime in two dimensions the system is respectively described\nby a marginal- or a non-Fermi liquid of relativistic spin-1/2 fermions\n(possessing a unique velocity), and is always a marginal Fermi liquid in three\ndimensions. We consider a possible generalization of these scenarios to\nfermions with an arbitrary half-odd-integer spin, and conjecture that critical\nspin-1/2 excitations represent a superuniversal description of the entire\nfamily of interacting quasi-relativistic fermions."
    },
    {
        "anchor": "Selective electron transfer between the quantum dots under the resonant\n  pulse: The coherent quantum dynamics of an electron in the quantum-dot ring\nstructure under the resonant electromagnetic pulse is studied theoretically. A\npossibility of the selective electron transfer between any two dots is\ndemonstrated. The transfer probability as a function of the pulse and dot\nparameters is calculated. It is shown that this probability can be close to\nunity. The factors lowering the transfer probability in real systems are\ndiscussed. The results obtained may be used in the engineering of novel\nnanoelectronic devices for quantum bits processing.",
        "positive": "Influence of multi-electronic states on few-quantum-dot nanolasers: We present an experimental and theoretical study on the gain mechanism in a\nphotonic-crystal-cavity nanolaser with embedded quantum dots. From\ntime-resolved measurements at low excitation power we find that four excitons\nare coupled to the cavity. At high excitation power we observe a smooth\nlow-threshold transition from spontaneous emission to lasing. Before lasing\nemission sets in, however, the excitons are observed to saturate, and the gain\nrequired for lasing originates rather from multi-electronic transitions, which\ngive rise to a broad emission background. We compare the experiment to a model\nof quantum-dot microcavity lasers and find that the number of emitters feeding\nthe cavity must greatly exceed four, which confirms that the gain is provided\nby multi-electronic states. Our results are consistent with theoretical\npredictions."
    },
    {
        "anchor": "On the conclusive detection of Majorana zero modes: conductance\n  spectroscopy, disconnected entanglement entropy and the fermion parity noise: Semiconducting nanowires with strong Rashba spin-orbit coupling in the\nproximity with a superconductor and under a strong Zeeman field can potentially\nmanifest Majorana zero modes at their edges and are a topical candidate for\ntopological superconductivity. However, protocols for their detection based on\nthe local and the non-local conductance spectroscopy have been subject to\nintense scrutiny. In this work, by taking current experimental setups into\naccount, we detail mathematical ideas related to the entanglement entropy and\nthe fermion parity fluctuations to faithfully distinguish between true Majorana\nzero modes and trivial quasi-Majorana zero modes. We demonstrate that the\ndisconnected entanglement entropy, derived from the von Neumann entanglement\nentropy, provides a distinct and robust signature of the topological phase\ntransition which is immune to system parameters, size and disorders. In order\nto understand the entanglement entropy of the Rashba nanowire system, we\nestablish its connection to a model of interacting spinfull Kitaev chains.\nMoreover, we relate the entanglement entropy to the fermionic parity\nfluctuation, and show that it behaves concordantly with entanglement entropy,\nhence making it a suitable metric for the detection of Majorana zero modes. In\nconnection with the topological gap protocol that is based on the conductance\nspectra, the aforesaid metrics can reliably point toward the topological\ntransitions even in realistic setups.",
        "positive": "Chiral Unitary Quantum Phase Transition in 2H-Fe$_x$TaSe$_2$: We have observed a metal-insulator transition of a quasi-two dimensional\nelectronic system in transition metal dichalcogenide $2H$-TaSe$_2$ caused by\ndoping iron. The sheet resistance of $2H$-Fe$_x$TaSe$_2$ ($0 \\leq x \\leq\n0.120$) single crystals rises about $10^6$ times with the increasing of $x$ at\nthe lowest temperature. We investigated the temperature dependence of the\nresistance and found a metal-insulator transition with a critical sheet\nresistance $11.7 \\pm 5.4$ k$\\rm{\\Omega}$. The critical exponent of the\nlocalization length $\\nu$ is estimated $0.31 \\pm 0.18$. The values of the\ncritical sheet resistance and $\\nu$ are accordant to those of the\n\\textit{chiral unitary class} (less than $h/1.49e^2=17.3$ k$\\rm{\\Omega}$ and\n$0.35 \\pm 0.03$, respectively). We suggest that $2H$-Fe$_x$TaSe$_2$ is\nclassified as the chiral unitary class, not as standard unitary class."
    },
    {
        "anchor": "Coherent Control of Two-Dimensional Excitons: Electric dipole radiation can be controlled by coherent optical feedback, as\nhas previously been studied by modulating the photonic environment for point\ndipoles placed both in optical cavities and near metal mirrors. In experiments\ninvolving fluorescent molecules, trapped ions and quantum dots the point nature\nof the dipole, its sub-unity quantum efficiency, and decoherence rate conspire\nto severely limit any change in total linewidth. Here we show that the\ntransverse coherence of exciton emission in the monolayer two-dimensional (2D)\nmaterial MoSe${}_2$ removes many of the fundamental physical limitations\npresent in previous experiments. The coherent interaction between excitons and\na photonic mode localized between the MoSe${}_2$ and a nearby planar mirror\ndepends interferometrically on mirror position, enabling full control over the\nradiative coupling rate from near-zero to 1.8 meV and a corresponding change in\nexciton total linewidth from 0.9 to 2.3 meV. The highly radiatively broadened\nexciton resonance (a ratio of up to $3:1$ in our samples) necessary to observe\nthis modulation is made possible by recent advances in 2D materials sample\nfabrication. Our method of mirror translation is free of any coupling to strain\nor DC electric field in the monolayer, which allows a fundamental study of this\nphotonic effect. The weak coherent driving field in our experiments yields a\nmean excitation occupation number of ${\\sim} 10^{-3}$ such that our experiments\ncorrespond to probing radiative reaction in the regime of perturbative quantum\nelectrodynamics. This system will serve as a testbed for exploring new\nexcitonic physics and quantum nonlinear optical effects.",
        "positive": "Structure and Morphology of Crystalline Metal Nanoparticles: Polyhedral\n  Cubic Particles: We examine nanoparticles (NPs) forming polyhedral sections of the ideal cubic\nlattice, simple (sc), body centered (bcc), and face centered (fcc) cubic, which\nare confined by facets characterized by densest and second densest {h k l}\nmonolayers of the lattice. Together with the constraint that the NPs exhibit\nthe same point symmetry as the ideal cubic lattice, i.e. Oh, different types of\ngeneric NPs serve for the definition of general polyhedral cubic NPs. Their\nstructural properties, such as shape, size, and surface facets, are discussed\nin analytical and numerical detail with visualization of characteristic\nexamples. The geometric relationships of the model particles expressed by\ncorresponding formulas and numerical tables can be used to estimate shapes and\nsizes of real compact metal nanoparticles observed by experiment."
    },
    {
        "anchor": "Role of optical rectification in photon-assisted tunneling current: We study the optical rectification in a metallic tunnel junction. We consider\na planar junction in a Kretschmann configuration and measure the\nphoton-assisted tunneling under infrared illumination at $\\lambda= 1.5\\, \\mu\n\\mathrm{m}$. To address the microscopic mechanism at the origin of the optical\nrectification, we compare the photon assisted current and the current-voltage\ncharacteristics of the junction measured on a voltage range much greater than\n$V_0=\\frac{hc}{e\\lambda}=0.825 \\, \\mathrm{V}$. The experimental results do not\nagree with the Tucker theory based on the exchange of energy quanta between\nelectrons and photons and describing the dc current induced by photon-assisted\nprocesses in terms of a linear combination of the shifted characteristics\n$I(V)$ and $I(V\\pm V_0)$. We show instead that the illumination power mainly\ngoes into heating and that the rectification results mainly from the\nnon-linearity of the tunnel junction at optical frequency.",
        "positive": "On the first-order phase transitions in a bistable large-spin systems\n  (Mn12Ac and others): We have shown that recent report concerning the first-order phase transitions\nin the large-spin systems is inaccurate. A kinetic numerical method for making\ncalculations of the transition rate in a bistable system as a function of\ntemperature has been evolved and a new critical value of the transition field\n(h=0.891) has been found. A physical mechanism caused transition from quantum\nto classical behavior has been discussed."
    },
    {
        "anchor": "Spin snake states with spin-orbit and Zeeman interactions in an\n  inhomogeneous magnetic field: We study the spin edge states, induced by the combined effect of\nBychkov-Rashba spin-orbit, Zeeman interactions and inhomogeneous magnetic\nfield, exposed perpendicularly to two-dimensional electron systems. We\ncalculate analytically the spectrum of the spin edge states (the spin snakes\norbits) in systems where the magnetic field exhibits a discontinuous jump in\nthe transverse direction and changes its sign at the magnetic interface. The\nobtained magnetic spin edge states in a 2DES exhibit several interesting\nproperties: in particular, electrons reverse their propagation direction at\nfinite values of their momentum.",
        "positive": "Discovery (theoretical prediction and experimental observation) of a\n  large-gap topological-insulator class with spin-polarized single-Dirac-cone\n  on the surface: Recent theories and experiments have suggested that strong spin-orbit\ncoupling effects in certain band insulators can give rise to a new phase of\nquantum matter, the so-called topological insulator, which can show macroscopic\nentanglement effects. Such systems feature two-dimensional surface states whose\nelectrodynamic properties are described not by the conventional Maxwell\nequations but rather by an attached axion field, originally proposed to\ndescribe strongly interacting particles. It has been proposed that a\ntopological insulator with a single spin-textured Dirac cone interfaced with a\nsuperconductor can form the most elementary unit for performing fault-tolerant\nquantum computation. Here we present an angle-resolved photoemission\nspectroscopy study and first-principle theoretical calculation-predictions that\nreveal the first observation of such a topological state of matter featuring a\nsingle-surface-Dirac-cone realized in the naturally occurring Bi$_2$Se$_3$\nclass of materials. Our results, supported by our theoretical predictions and\ncalculations, demonstrate that undoped compound of this class of materials can\nserve as the parent matrix compound for the long-sought topological device\nwhere in-plane surface carrier transport would have a purely quantum\ntopological origin. Our study further suggests that the undoped compound\nreached via n-to-p doping should show topological transport phenomena even at\nroom temperature."
    },
    {
        "anchor": "Graphene hot-electron light bulb: incandescence from hBN-encapsulated\n  graphene in air: The excellent electronic and mechanical properties of graphene allow it to\nsustain very large currents, enabling its incandescence through Joule heating\nin suspended devices. Although interesting scientifically and promising\ntechnologically, this process is unattainable in ambient environment, because\ngraphene quickly oxidises at high temperatures. Here, we take the performance\nof graphene-based incandescent devices to the next level by encapsulating\ngraphene with hexagonal boron nitride (hBN). Remarkably, we found that the hBN\nencapsulation provides an excellent protection for hot graphene filaments even\nat temperatures well above 2000 K. Unrivalled oxidation resistance of hBN\ncombined with atomically clean graphene/hBN interface allows for a stable light\nemission from our devices in atmosphere for many hours of continuous operation.\nFurthermore, when confined in a simple photonic cavity, the thermal emission\nspectrum is modified by a cavity mode, shifting the emission to the visible\nrange spectrum. We believe our results demonstrate that hBN/graphene\nheterostructures can be used to conveniently explore the technologically\nimportant high-temperature regime and to pave the way for future optoelectronic\napplications of graphene-based systems.",
        "positive": "Ab-initio Modeling of CBRAM Cells: from Ballistic Transport Properties\n  to Electro-Thermal Effects: We present atomistic simulations of conductive bridging random access memory\n(CBRAM) cells from first-principles combining density-functional theory and the\nNon-equilibrium Green's Function formalism. Realistic device structures with an\natomic-scale filament connecting two metallic contacts have been constructed.\nTheir transport properties have been studied in the ballistic limit and in the\npresence of electron-phonon scattering, showing good agreement with\nexperimental data. It has been found that the relocation of few atoms is\nsufficient to change the resistance of the CBRAM by 6 orders of magnitude, that\nthe electron trajectories strongly depend on the filament morphology, and that\nself-heating does not affect the device performance at currents below 1 $\\mu$A."
    },
    {
        "anchor": "Optoelectronic switch based on intrinsic dual Schottky diodes in\n  ambipolar MoSe$_2$ field-effect transistors: Here, we report the observation of a hitherto unreported optoelectronic\neffect, namely a light-induced diode-like response in multi-layered MoSe$_2$\nfield-effect transistors whose sense of current rectification is controllable\nthrough a gate voltage. We argue, through numerical simulations, that this\nbehavior results from the difference in the size of the Schottky barriers\nbetween drain and source metal contacts. Each barrier can be modeled as a\nSchottky diode but with opposite senses of current rectification between them,\nwith the diode response resulting from the light induced promotion of\nphoto-generated carriers across the smaller barrier. The back gate voltage\ncontrols the sense of current rectification by modulating the relative\namplitude between them. This effect, which gives rise to a novel type of\noptoelectronic switch, also yields a photovoltaic response. Hence, it could\nprovide an alternative to PN-junctions when harvesting photovoltaic currents\nfrom transition metal dichalcogenides. We argue that the photovoltaic\nefficiency associated to this effect could be increased by just increasing the\nrelative asymmetry between both Schottky barriers. We also suggest that this\nnew electro-optical effect has potential for technological applications.",
        "positive": "Spin-dependent zero-bias peak in a hybrid nanowire-quantum dot system:\n  Distinguishing isolated Majorana fermions from Andreev bound states: Hybrid system composed by a semiconducting nanowire with proximity-induced\nsuperconductivity and a quantum dot at the end working as spectrometer was\nrecently used to quantify the so-called degree of Majorana nonlocality [Deng et\nal., Phys.Rev.B, 98, 085125 (2018)]. Here we demonstrate that spin-resolved\ndensity of states of the dot responsible for zero-bias conductance peak\nstrongly depends on the separation between the Majorana bound states (MBSs) and\ntheir relative couplings with the dot and investigate how the charging energy\naffects the spectrum of the system in the distinct scenarios of Majorana\nnonlocality (topological quality). Our findings suggest that spin-resolved\nspectroscopy of the local density of states of the dot can be used as a\npowerful tool for discriminating between different scenarios of the emergence\nof zero-bias conductance peak."
    },
    {
        "anchor": "SU(4) Kondo Effect in Carbon Nanotubes: We investigate theoretically the non-equilibrium transport properties of\ncarbon nanotube quantum dots. Owing to the two-dimensional band structure of\ngraphene, a double orbital degeneracy plays the role of a pseudo-spin, which is\nentangled with the spin. Quantum fluctuations between these four degrees of\nfreedom result in an SU(4) Kondo effect at low temperatures. This exotic Kondo\neffect manifests as a four-peak splitting in the non-linear conductance when an\naxial magnetic field is applied.",
        "positive": "Non-equilibrium current and noise in inelastic tunneling through a\n  magnetic atom: In a recent experiment, Hirjibehedin {\\it et al.} [Science {\\bf 317}, 1199\n(2007)] performed inelastic tunneling spectroscopy of a single iron atom\nabsorbed on a nonmagnetic substrate. The observed steps in the differential\nconductance marked the spin excitation energies. In this Letter, we explain\nobserved nonmonotonicities in the differential conductance by a nonequilibrium\npopulation of the atom spin states. Furthermore, we predict super-Poissonian\ncurrent noise due to this nonequilibrium situation. By introducing an\nanisotropic relaxation channel we are also able to explain the remarkable\nabsence of nonequilibrium features at certain conductance steps."
    },
    {
        "anchor": "Anderson-Bogoliubov and Carlson-Goldman modes in counterflow\n  superconductors: Case study of a double monolayer graphene: The impact of electron-hole pairing on the spectrum of plasma excitations in\ndouble layer systems is investigated. The theory is developed with reference to\na double monolayer graphene. Taking into account the coupling of scalar\npotential oscillations with oscillations of the order parameter $\\Delta$, we\nshow that the spectrum of antisymmetric (acoustic) plasma excitations contains\ntwo modes: a weakly damped mode below the gap $2\\Delta$ and a strongly damped\nmode above the gap. The lower mode can be interpreted as an analog of the\nCarlson-Goldman mode. This mode has an acoustic dispersion relation at small\nwave vectors and it saturates at the level $2\\Delta$ at large wave vectors. Its\nvelocity is larger than the velocity of the Anderson-Bogoliubov mode\n$v_{AB}=v_F$/$\\sqrt{2}$, and it can be smaller than the Fermi velocity $v_F$.\nThe damping rate of this mode strongly increases under increase of temperature.\nOut-of-phase oscillations of two order parameters in two spin subsystems are\nalso considered. This part of the spectrum contains two more modes. One of them\nis interpreted as an analog of the Anderson-Bogoliubov (phase) mode and the\nother, as an analog of the Schmid (amplitude) mode. With minor modifications\nthe theory can be extended to describe collective modes in a double bilayer\ngraphene as well.",
        "positive": "Graphene photodetectors for high-speed optical communications: While silicon has dominated solid-state electronics for more than four\ndecades, a variety of new materials have been introduced into photonics to\nexpand the accessible wavelength range and to improve the performance of\nphotonic devices. For example, gallium-nitride based materials enable the light\nemission at blue and ultraviolet wavelengths, and high index contrast\nsilicon-on-insulator facilitates the realization of ultra dense and CMOS\ncompatible photonic devices. Here, we report the first deployment of graphene,\na two-dimensional carbon material, as the photo-detection element in a 10\nGbits/s optical data link. In this interdigitated metal-graphene-metal\nphotodetector, an asymmetric metallization scheme is adopted to break the\nmirror symmetry of the built-in electric-field profile in conventional graphene\nfield-effect-transistor channels, allowing for efficient photo-detection within\nthe entire area of light illumination. A maximum external photo-responsivity of\n6.1 mA/W is achieved at 1.55 {\\mu}m wavelength, a very impressive value given\nthat the material is below one nanometer in thickness. Moreover, owing to the\nunique band structure and exceptional electronic properties of graphene, high\nspeed photodetectors with an ultra-wide operational wavelength range at least\nfrom 300 nm to 6 {\\mu}m can be realized using this fascinating material."
    },
    {
        "anchor": "Transmission through a defect in polyacene: the extreme limit of ultra\n  narrow graphene: We compute the transmission of an electron through an impurity in polyacene.\nAn analytical expression for the transmission coefficient is found. For\nsimplicity the disorder is confined to a single unit cell, but the\ngeneralization to several unit cells is straightforward. Both on-site and\noff-diagonal defects are considered. When the impurity preserves the inversion\nsymmetry around the central axis, the scattering problem can be reduced to that\nof two independent chains with an alternating sequence of two types of atoms.",
        "positive": "Giant violation of Wiedemann-Franz law in doping layers of modern AlGaAs\n  heterostructures: We analyze the data of the recent paper Nature 559, 205 (2018) and show that\nit contains an observation of thermal and electric conductivities of the doping\nlayers in GaAs/AlGaAs heterostructures which violates the Wiedemann-Franz law.\nNamely, the measured thermal conductivity of the doping layers is similar to\nthat of a metal while the electrical conductivity is exponentially small. We\nfind that these results may be related to the exciton contribution to thermal\nconductivity calculated in several recent theoretical works for metallic\nsamples."
    },
    {
        "anchor": "The epitaxial-graphene/graphene-oxide junction, an essential step\n  towards epitaxial graphene electronics: Graphene oxide (GO) flakes have been deposited to bridge the gap between two\nepitaxial graphene electrodes to produce all-graphene devices. Electrical\nmeasurements indicate the presence of Schottky barriers (SB) at the\ngraphene/graphene oxide junctions, as a consequence of the band-gap in GO. The\nbarrier height is found to be about 0.7 eV, and is reduced after annealing at\n180 $^\\circ$C, implying that the gap can be tuned by changing the degree of\noxidation. A lower limit of the GO mobility was found to be 850 cm$^2$/Vs,\nrivaling silicon. {\\it In situ} local oxidation of patterned epitaxial graphene\nhas been achieved.",
        "positive": "Hybrid topological photonic crystals: Photonic topological phases offering unprecedented manipulation of\nelectromagnetic waves have attracted much research interest which, however,\nhave been mostly restricted to a single band gap. Here, we report on the\nexperimental discovery of hybrid topological photonic crystals which host\nsimultaneously quantum anomalous Hall and valley Hall phases in different\nphotonic band gaps. The underlying hybrid topological phase manifests itself in\nthe edge responses as the coexistence of the chiral edge states and valley Hall\nedge states in different frequency ranges. We experimentally verify such an\nemergent phenomenon and show that such a feature enables novel multiplexing of\nphoton transport in the edge channels. Our study reveals a situation with\ncoexisting topology of distinct nature in a single photonic system that may\nenable frequency-dependent filtering and manipulation of topological edge\nphotons."
    },
    {
        "anchor": "Dephasing with strings attached: Motivated by the existence of mobile low-energy excitations like domain walls\nin one dimension or gauge-charged fractionalized particles in higher\ndimensions, we compare quantum dynamics in the presence of weak Markovian\ndephasing for a particle hopping on a chain and for an Ising domain wall whose\nmotion leaves behind a string of flipped spins. Exact solutions show that the\ntwo models have near identical transport responses in the bulk. On the other\nhand, in finite-length chains, the broadening of discrete spectral lines is\nmuch more noticeable in the case of a domain wall. These results may be of\nrelevance to a broad class of systems including quasi-1D antiferromagnets,\npolymer chains, and even retinal systems.",
        "positive": "Coulomb-promoted spintromechanics in magnetic shuttle devices: Exchange forces on the movable dot (\"shuttle\") in a magnetic shuttle device\ndepend on the parity of the number of shuttling electrons. The performance of\nsuch a device can therefore be tuned by changing the strength $U$ of Coulomb\ncorrelations to block or unblock parity fluctuations. We show that by\nincreasing $U$ the spintro-mechanics of the device crosses over, at $U=U_c(T)$,\nfrom a mechanically stable regime to a regime of spin-induced shuttle\ninstabilities. This is due to enhanced spin-dependent mechanical forces as\nparity fluctuations are reduced by a Coulomb blockade of tunneling and\ndemonstrates that single-electron manipulation of single-spin controlled\nnano-mechanics is possible."
    },
    {
        "anchor": "Magnetoconductance correction in zinc-blende semiconductor nanowires\n  with spin-orbit coupling: We study the effects of spin-orbit coupling on the magnetoconductivity in\ndiffusive cylindrical semiconductor nanowires. Following up on our former study\non tubular semiconductor nanowires, we focus in this paper on nanowire systems\nwhere no surface accumulation layer is formed but instead the electron wave\nfunction extends over the entire cross section. We take into account the\nDresselhaus spin-orbit coupling resulting from a zinc-blende lattice and the\nRashba spin-orbit coupling, which is controlled by a lateral gate electrode.\nThe spin relaxation rate due to Dresselhaus spin-orbit coupling is found to\ndepend neither on the spin density component nor on the wire growth direction\nand is unaffected by the radial boundary. In contrast, the Rashba spin\nrelaxation rate is strongly reduced for a wire radius that is smaller than the\nspin precession length. The derived model is fitted to the data of\nmagnetoconductance measurements of a heavily doped back-gated InAs nanowire and\ntransport parameters are extracted. At last, we compare our results to previous\ntheoretical and experimental studies and discuss the occurring discrepancies.",
        "positive": "Chiral excitation of spin waves in ferromagnetic films: We theoretically investigate the interlayer dipolar and exchange couplings\nfor an array of metallic magnetic nanowires grown on top of an extended\nultrathin yttrium iron garnet film. The calculated interlayer dipolar coupling\nagrees with observed anticrossings [Chen \\emph{et al.}, Phys. Rev. Lett.\n\\textbf{120}, 217202 (2018)], concluding that the interlayer exchange coupling\nis suppressed by a spacer layer between the nanowires and film. The Kittel mode\nin the nanowire array couples chirally to spin waves in the film, even though\nDamon-Eshbach surface modes do not exist. The chirality is suppressed when the\ninterlayer exchange coupling becomes strong."
    },
    {
        "anchor": "Transport properties of a non-Hermitian Weyl semimetal: In recent years, non-Hermitian (NH) topological semimetals have garnered\nsignificant attention due to their unconventional properties. In this work, we\nexplore the transport properties of a three-dimensional dissipative Weyl\nsemi-metal formed as a result of the stacking of two-dimensional Chern\ninsulators. We find that unlike Hermitian systems where the Hall conductance is\nquantized, in presence of non-Hermiticity, the quantized Hall conductance\nstarts to deviate from its usual nature. We show that the non-quantized nature\nof the Hall conductance in such NH topological systems is intimately connected\nto the presence of exceptional points (EPs). We find that in the case of open\nboundary conditions, the transition from a topologically trivial regime to a\nnon-trivial topological regime takes place at a different value of the momentum\nthan that of the periodic boundary spectra. This discrepancy is solved by\nconsidering the non-Bloch case and the generalized Brillouin zone (GBZ).\nFinally, we present the Hall conductance evaluated over the GBZ and connect it\nto the separation between the Weyl nodes, within the non-Bloch theory.",
        "positive": "Dynamical phenomena in Fibonacci Semiconductor Superlattices: We present a detailed study of the dynamics of electronic wavepackets in\nFibonacci semiconductor superlattices, both in flat band conditions and subject\nto homogeneous electric fields perpendicular to the layers. Coherent\npropagation of electrons is described by means of a scalar Hamiltonian using\nthe effective-mass approximation. We have found that an initial Gaussian\nwavepacket is filtered selectively when passing through the superlattice. This\nmeans that only those components of the wavepacket whose wavenumber belong to\nallowed subminibands of the fractal-like energy spectrum can propagate over the\nentire superlattice. The Fourier pattern of the transmitted part of the\nwavepacket presents clear evidences of fractality reproducing those of the\nunderlying energy spectrum. This phenomenon persists even in the presence of\nunintentional disorder due to growth imperfections. Finally, we have\ndemonstrated that periodic coherent-field induced oscillations (Bloch\noscillations), which we are able to observe in our simulations of periodic\nsuperlattices, are replaced in Fibonacci superlattices by more complex\noscillations displaying quasiperiodic signatures, thus sheding more light onto\nthe very peculiar nature of the electronic states in these systems."
    },
    {
        "anchor": "Direct measurement of the electron-phonon relaxation rate in thin copper\n  films: We have used normal metal-insulator-superconductor (NIS) tunnel junction\npairs, known as SINIS structures, for ultrasensitive thermometry at sub-Kelvin\ntemperatures. With the help of these thermometers, we have developed an\nac-technique to measure the electron-phonon (e-p) scattering rate directly,\nwithout any other material or geometry dependent parameters, based on\noverheating the electron gas. The technique is based on Joule heating the\nelectrons in the frequency range DC-10 MHz, and measuring the electron\ntemperature in DC. Because of the nonlinearity of the electron-phonon coupling\nwith respect to temperature, even the DC response will be affected, when the\nheating frequency reaches the natural cut-off determined by the e-p scattering\nrate. Results on thin Cu films show a $T^{4}$ behavior for the scattering rate,\nin agreement with indirect measurement of similar samples and numerical\nmodeling of the non-linear response.",
        "positive": "All-electrical measurements of direct spin Hall effect in GaAs with\n  Esaki diode electrodes: We report on measurements of direct spin Hall effect in a lightly n-doped\nGaAs channel. As spin detecting contacts we employed highly efficient\nferromagnetic Fe/(Ga,Mn)As/GaAs Esaki diode structures. We investigate bias and\ntemperature dependence of the measured spin Hall signal and evaluate the value\nof total spin Hall conductivity and its dependence on channel conductivity and\ntemperature. From the results we determine skew scattering and side jump\ncontribution to the total spin hall conductivity and compare it with the\nresults of experiments on higher conductive n-GaAs channels[Phys. Rev. Lett.\n105,156602(2010)]. As a result we conclude that both skewness and side jump\ncontribution cannot be fully independent on the conductivity of the channel."
    },
    {
        "anchor": "Lithium atom storage in nanoporous cellulose via surface induced $\\rm\n  Li_2$ breakage: We demonstrate a physical mechanism that enhances a splitting of diatomic\n$\\rm Li_2$ at cellulose surfaces. The origin of this splitting is a possible\nsurface induced diatomic excited state resonance repulsion. The atomic Li is\nthen free to form either physical or chemical bonds with the cellulose surface\nand even diffuse into the cellulose layer structure. This allows for an\nenhanced storage capacity of atomic Li in nanoporous cellulose",
        "positive": "Low temperature photo-physics of single NV centers in diamond: We investigate the magnetic field dependent photo-physics of individual\nNitrogen-Vacancy (NV) color centers in diamond under cryogenic conditions. At\ndistinct magnetic fields, we observe significant reductions in the NV\nphotoluminescence rate, which indicate a marked decrease in the optical readout\nefficiency of the NV's ground state spin. We assign these dips to excited state\nlevel anti-crossings, which occur at magnetic fields that strongly depend on\nthe effective, local strain environment of the NV center. Our results offer new\ninsights into the structure of the NVs' excited states and a new tool for their\neffective characterization. Using this tool, we observe strong indications for\nstrain-dependent variations of the NV's orbital g-factor, obtain new insights\ninto NV charge state dynamics, and draw important conclusions regarding the\napplicability of NV centers for low-temperature quantum sensing."
    },
    {
        "anchor": "Tuning the Conductance of Monatomic Carbon Chain: Ab initio calculations show that the conductance of short monatomic carbon\nchain can be dramatically modified by adhering a single H, N, or O atom to the\nchain. For example, the conductance of the pristine chain gets about two orders\nof magnitude smaller if an H atom is adhered to the chain. By a statistical\nmodel, the structure of the carbon chain with the single atom adhered is found\nto be quite stable at room temperature, indicating that the method can be used\nto tune the conductance of monatomic carbon chain.",
        "positive": "Resonant spin amplification meets electron spin resonance in $n$-GaAs: Periodic excitation of electron spin polarization by consecutive laser pulses\nin phase with Larmor spin precession about a magnetic field results in resonant\nspin amplification (RSA). We observe a drastic modification of RSA in $n$-doped\nbulk GaAs under the influence of external oscillating magnetic field. We find a\ndouble-peaked electron spin resonance instead of a single-peaked resonance\nexpected without optical pumping. The frequency splitting increases linearly\nwith amplitude of field oscillations, while the spin deviation increases\nquadratically. Moreover, we show that the oscillating field can both\nsignificantly suppress RSA and induce new conditions for resonance. Using\nquaternions to describe spin rotations, we develop a theory that simultaneously\nconsiders spin precession, decay, and amplification and reproduces the entire\nset of the experimental data. Using the radio-frequency field allows one to\ncontrol the conditions of RSA and achieve fine tuning of average spin\npolarization without modifying the parameters of optical pumping."
    },
    {
        "anchor": "Pi-stacking functionalization through micelles swelling: Application to\n  the synthesis of single wall carbon nanotube/porphyrin complexes for energy\n  transfer: We report on a new, orginal and efficient method for \"pi-stacking\"\nfunctionalization of single wall carbon nanotubes. This method is applied to\nthe synthesis of a high-yield light-harvesting system combining single wall\ncarbon nanotubes and porphyrin molecules. We developed a micelle swelling\ntechnique that leads to controlled and stable complexes presenting an efficient\nenergy transfer. We demonstrate the key role of the organic solvent in the\nfunctionalization mechanism. By swelling the micelles, the solvent helps the\nnon water soluble porphyrins to reach the micelle core and allows a strong\nenhancement of the interaction between porphyrins and nanotubes. This technique\nopens new avenues for the functionalization of carbon nanostructures.",
        "positive": "Self-interaction effects in (Ga,Mn)As and (Ga,Mn)N: The electronic structures of Mn-doped zincblende GaAs and wurtzite GaN are\ncalculated using both standard local-density functional theory (LSDA), and a\nnovel pseudopotential self-interaction-corrected approach (pseudo-SIC), able to\naccount for the effects of strong correlation. We find that, as expected, the\nself-interaction is not strong in (Ga,Mn)As, because the Fermi energy is\ncrossed by weakly correlated As p - Mn d hybridized bands and the Mn 3d\ncharacter is distributed through the whole valence band manifold. This result\nvalidates the extensive literature of LSDA studies on (Ga,Mn)As, including the\nconclusion that the ferromagnetism is hole-mediated. In contrast, the LSDA\ngives a qualitatively incorrect band structure for (Ga,Mn)N, which is\ncharacterized by localized Mn 3d bands with very strong self-interaction. Our\npseudo-SIC calculations show a highly confined hole just above the Fermi energy\nin the majority band manifold. Such a band arrangement is consistent with\n(although by no means conclusive evidence for) a recent suggestion that\nformation of Zhang-Rice magnetic polarons is responsible for hole-mediated\nferromagnetism in (Ga,Mn)N."
    },
    {
        "anchor": "Rashba spin splitting in biased semiconductor quantum wells: Rashba spin splitting (RSS) in biased semiconductor quantum wells is\ninvestigated theoretically based on the eight-band envelope function model. We\nfind that at large wave vectors, RSS is both nonmonotonic and anisotropic as a\nfunction of in-plane wave vector, in contrast to the widely used linear and\nisotropic model. We derive an analytical expression for RSS, which can\ncorrectly reproduce such nonmonotonic behavior at large wave vectors. We also\ninvestigate numerically the dependence of RSS on the various band parameters\nand find that RSS increases with decreasing band gap and subband index,\nincreasing valence band offset, external electric field, and well width. Our\nanalytical expression for RSS provides a satisfactory explanation to all these\nfeatures.",
        "positive": "Effect of the electromagnetic environment on current fluctuations in\n  driven tunnel junctions: We examine current fluctuations in tunnel junctions driven by a superposition\nof a constant and a sinusoidal voltage source. In standard setups the external\nvoltage is applied to the tunneling element via an impedance providing an\nelectromagnetic environment of the junction. The modes of this environment are\nexcited by the time-dependent voltage and are the source of Johnson-Nyquist\nnoise. We determine the autocorrelation function of the current flowing in the\nleads of the junction in the weak tunneling limit up to terms of second order\nin the tunneling Hamiltonian. The driven modes of the electromagnetic\nenvironment are treated exactly by means of a unitary transformation introduced\nrecently. Particular emphasis is placed on the spectral function of the current\nfluctuations. The spectrum is found to comprise three contributions: a term\narising from the Johnson-Nyquist noise of the environmental impedance, a part\ndue to the shot noise of the tunneling element and a third contribution which\ncomes from the cross-correlation between fluctuations caused by the\nelectromagnetic environment and fluctuations of the tunneling current. All\nthree parts of the spectral function occur already for devices under dc bias.\nThe spectral function of ac driven tunneling elements can be determined from\nthe result for a dc bias by means of a photo-assisted tunneling relation of the\nTien-Gordon type. Specific results are given for an Ohmic environment and for a\njunction driven through a resonator."
    },
    {
        "anchor": "A Transfer Hamiltonian model for devices based in quantum dot arrays: We present a model of electron transport through a random distribution of\ninteracting quantum dots embedded in a dielectric matrix to simulate realistic\ndevices. The method underlying the model depends only on fundamental parameters\nof the system and it is based on the Transfer Hamiltonian approach. A set of\nnon-coherent rate equations can be written and the interaction between the\nquantum dots and between the quantum dots and the electrodes are introduced by\ntransition rates and capacitive couplings. A realistic modelization of the\ncapacitive couplings, the transmission coefficients, the electron/hole\ntunneling currents and the density of states of each quantum dot have been\ntaken into account. The effects of the local potential are computed within the\nself-consistent field regime.",
        "positive": "Minimal setup for non-Abelian braiding of Majorana zero modes: Braiding Majorana zero modes (MZMs) is the key procedure toward topological\nquantum computation. However, the complexity of the braiding manipulation\nhinders its experimental realization. Here we propose an experimental setup\ncomposing of MZMs and a quantum dot state which can substantially simplify the\nbraiding protocol of MZMs. Such braiding scheme, which corresponds to a\nspecific closed loop in the parameter space, is quite universal and can be\nrealized in various platforms. Moreover, the braiding results can be directly\nmeasured and manifested through electric current, which provides a simple and\nnovel way to detect the non-Abelian statistics of MZMs."
    },
    {
        "anchor": "Disconnected Elementary Band Representations, Fragile Topology, and\n  Wilson Loops as Topological Indices: An Example on the Triangular Lattice: In this work, we examine the topological phases that can arise in triangular\nlattices with disconnected elementary band representations. We show that,\nalthough these phases may be \"fragile\" with respect to the addition of extra\nbands, their topological properties are manifest in certain nontrivial\nholonomies (Wilson loops) in the space of nontrivial bands. We introduce an\neigenvalue index for fragile topology, and we show how a nontrivial value of\nthis index manifests as the winding of a hexagonal Wilson loop; this remains\ntrue even in the absence of time-reversal or sixfold rotational symmetry.\nAdditionally, when time-reversal and twofold rotational symmetry are present,\nwe show directly that there is a protected nontrivial winding in more\nconventional Wilson loops. Crucially, we emphasize that these Wilson loops\ncannot change without closing a gap to the nontrivial bands. By studying the\nentanglement spectrum for the fragile bands, we comment on the relationship\nbetween fragile topology and the \"obstructed atomic limit\" of B. Bradlyn et\nal., Nature 547, 298--305 (2017). We conclude with some perspectives on\ntopological matter beyond the K-theory classification.",
        "positive": "Hydrogen storage in rippled graphene: perspectives from multi-scale\n  simulations: Exploring new perspectives for green technologies is one of the challenges of\nthe third millennium, in which the need for non-polluting and renewable\npowering has become primary. In this context, the use of hydrogen as a fuel is\npromising, since the energy released in its oxidation (~285 kJ/mole) is three\ntimes that released, on average, by hydrocarbons, and the combustion product is\nwater (Ramage, 1983). Being hydrogen a vector of chemical energy, efficient\nconservation and non-dispersive transportation are the main goals. Three issues\nmust be considered to this respect: (i) storage capacity (ii) storage stability\n(iii) kinetics of loading/release. Commercial technologies are currently based\non cryo-compression or liquefaction of H2 in tanks. These ensure quite a high\ngravimetric density (GD, point (i)), namely 8-13% in weight of stored hydrogen,\nand a relatively low cost (Z\\\"uttel 2003). However concerning points (ii) and\n(iii), these technologies pose problems of safety, mainly due to explosive\nflammability of hydrogen, and consequent unpractical conditions for\ntransportation and use (Mori et al 2009). Therefore, research efforts are\ndirected towards solid-state based storage systems (energy.gov, Bonaccorso et\nal 2015)."
    },
    {
        "anchor": "Coherent spin transport and suppression of spin relaxation in InSb\n  nanowires with single subband occupancy at room temperature: A longstanding goal of spintronics is to inject, coherently transport, and\ndetect spins in a semiconductor nanowire where a SINGLE quantized subband is\noccupied at room temperature. Here, we report achieving this goal in 50-nm\ndiameter InSb nanowires by demonstrating both the spin-valve and the Hanle\neffect. The spin relaxation time in the nanowires was found to have increased\nby an order of magnitude over what has been reported in bulk and quantum wells\ndue to the suppression of D'yakonov-Perel' spin relaxation as a result of\nsingle subband occupancy. These experiments raise hopes for the realization of\na room-temperature Datta-Das spin transistor.",
        "positive": "Quasiparticles in superconducting qubits with asymmetric junctions: Designing the spatial profile of the superconducting gap -- gap engineering\n-- has long been recognized as an effective way of controlling quasiparticles\nin superconducting devices. In aluminum films, their thickness modulates the\ngap; therefore, standard fabrication of Al/AlOx/Al Josephson junctions, which\nrelies on overlapping a thicker film on top of a thinner one, always results in\ngap-engineered devices. Here we reconsider quasiparticle effects in\nsuperconducting qubits to explicitly account for the unavoidable asymmetry in\nthe gap on the two sides of a Josephson junction. We find that different\nregimes can be encountered in which the quasiparticles have either similar\ndensities in the two junction leads, or are largely confined to the lower-gap\nlead. Qualitatively, for similar densities the qubit's excited state population\nis lower but its relaxation rate higher than when the quasiparticles are\nconfined; therefore, there is a potential trade-off between two desirable\nproperties in a qubit."
    },
    {
        "anchor": "Swing switching of spin-torque valves: We propose a method for inducing magnetization reversal using an AC spin\ncurrent polarized perpendicular to the equilibrium magnetization of the free\nmagnetic layer. We show that the critical AC spin current is significantly\nsmaller than the corresponding DC one. The effect is understood as a\nconsequence of the underdamped nature of the spin-torque oscillators. It allows\nto use the kinetic inertia to overcome the residual energy barrier, rather than\nsuppressing the latter by a large spin current. The effect is similar to a\nswing which may be set into high amplitude motion by a weak near-resonant push.\nThe optimal AC frequency is identified as the upper bifurcation frequency of\nthe corresponding driven nonlinear oscillator. Together with fast switching\ntimes it makes the perpendicular AC method to be the most efficient way to\nrealize spin-torque memory valve.",
        "positive": "Topological semimetals with Riemann surface states: Riemann surfaces are geometric constructions in complex analysis that may\nrepresent multi-valued holomorphic functions using multiple sheets of the\ncomplex plane. We show that the energy dispersion of surface states in\ntopological semimetals can be represented by Riemann surfaces generated by\nholomorphic functions in the two-dimensional momentum space, whose constant\nheight contours correspond to Fermi arcs. This correspondence is demonstrated\nin the recently discovered Weyl semimetals and leads us to predict new types of\ntopological semimetals, whose surface states are represented by double- and\nquad-helicoid Riemann surfaces. The intersection of multiple helicoids, or the\nbranch cut of the generating function, appears on high-symmetry lines in the\nsurface Brillouin zone, where surface states are guaranteed to be doubly\ndegenerate by a glide reflection symmetry. We predict the heterostructure\nsuperlattice [(SrIrO$_3$)$_2$(CaIrO$_3$)$_2$] to be a topological semimetal\nwith double-helicoid Riemann surface states."
    },
    {
        "anchor": "Graphene plasmonics: A platform for strong light-matter interaction: Graphene plasmons provide a suitable alternative to noble-metal plasmons\nbecause they exhibit much larger confinement and relatively long propagation\ndistances, with the advantage of being highly tunable via electrostatic gating.\nWe report strong light- matter interaction assisted by graphene plasmons, and\nin particular, we predict unprecedented high decay rates of quantum emitters in\nthe proximity of a carbon sheet, large vacuum Rabi splitting and Purcell\nfactors, and extinction cross sections exceeding the geometrical area in\ngraphene ribbons and nanometer-sized disks. Our results provide the basis for\nthe emerging and potentially far-reaching field of graphene plasmonics,\noffering an ideal platform for cavity quantum electrodynamics and supporting\nthe possibility of single-molecule, single-plasmon devices.",
        "positive": "Tailoring magnetization reversal of a single-domain bar nanomagnet via\n  its end geometry: Nanoscale single-domain bar magnets are building blocks for a variety of\nfundamental and applied mesoscopic magnetic systems, such as artificial spin\nices, magnetic shape-morphing microbots as well as magnetic majority logic\ngates. The magnetization reversal switching field of the bar nanomagnets is a\ncrucial parameter that determines the physical properties and functionalities\nof their constituted artificial systems. Previous methods on tuning the\nmagnetization reversal switching field of a bar nanomagnet usually rely on\nmodifying its aspect ratio, such as its length, width and/or thickness. Here,\nwe show that the switching field of a bar nanomagnet saturates when extending\nits length beyond a certain value, preventing further tailoring of the\nmagnetization reversal via aspect ratios. We showcase highly tunable switching\nfield of a bar nanomagent by tailoring its end geometry without altering its\nsize. This provides an easy method to control the magnetization reversal of a\nsingle-domain bar nanomagnet. It would enable new research and/or applications,\nsuch as designing artificial spin ices with additional tuning parameters,\nengineering magnetic microbots with more flexibility as well as developing\nmagnetic quantum-dot cellular automata systems for low power computing."
    },
    {
        "anchor": "Critical radius and temperature for buckling in graphene: In this work, we find an analytical flat-membrane solution to the saddle\npoint equations, derived by Guinea et al. [Phys. Rev. B 89, 125428 (2014)], for\nthe case of a suspended graphene membrane of circular shape. We also find how\ndifferent buckled membrane solutions bifurcate from the flat membrane at\ncritical temperatures and membrane radii. The saddle point equations take into\naccount electron-phonon coupling and this coupling provides a residual stress\neven for a flat graphene layer. Below a critical temperature (which is\nexceedingly high for an infinite layer) or above a critical size that depend on\nboundary conditions, different buckling modes that may be the germ of rippling\nappear. Our results provide the opportunity to develop new feasible experiments\ndealing with buckling in small suspended graphene membranes that could verify\nthem. These experiments may also be used to fit the phonon-electron coupling\nconstant or the bending energy.",
        "positive": "Hall effect in Poiseuille flow of two-dimensional electron fluid: The hydrodynamic regime of charge transport has been recently realized in\nhigh-quality conductors. In the hydrodynamic as well as in the Ohmic regimes\nthe main part of the Hall resistance of a long sample is determined by the\nbalance between the Lorentz force and the electric force, acting on conduction\nelectrons. Experimentally observed deviations of the Hall resistance in\nhydrodynamic samples from such the ''standard'' value are usually associated\nwith the Hall viscosity term in the Navier-Stokes equation. In this work we\ntheoretically study the Hall effect in a Poiseuille flow of a two-dimensional\nelectron fluid. We show that the near-edge semiballistic layers with the width\nof the order of the inter-particle mean free path, which inevitably appear near\nsample edges, give the contribution to the Hall resistance which is comparable\nwith the bulk contribution from the Hall viscosity. In this way, the measured\ndeviations of the Hall resistance from the ''standard'' one in hydrodynamic\nsamples by the usual contact techniques should be associated with both the Hall\nviscosity in the bulk and the semiballistic effects in the near-edge layers"
    },
    {
        "anchor": "Global topology of Weyl semimetals and Fermi arcs: We provide a manifestly topological classification scheme for generalised\nWeyl semimetals, in any spatial dimension and with arbitrary Weyl surfaces\nwhich may be non-trivially linked. The classification naturally incorporates\nthat of Chern insulators. Our analysis refines, in a mathematically precise\nsense, some well-known 3D constructions to account for subtle but important\nglobal aspects of the topology of semimetals. Using a fundamental locality\nprinciple, we derive a generalized charge cancellation condition for the Weyl\nsurface components. We analyse the bulk-boundary correspondence under a duality\ntransformation, which reveals explicitly the topological nature of the\nresulting surface Fermi arcs. We also analyse the effect of moving Weyl points\non the bulk and boundary topological semimetal invariants.",
        "positive": "Magnetic ion relaxation time distribution within a quantum well: Time-resolved optically detected magnetic resonance (ODMR) is a valuable\ntechnique to study the local deformation of the crystal lattice around magnetic\nion as well as the ion spin relaxation time. Here we utilize selective\nMn-doping to additionally enhance the inherent locality of the ODMR technique.\nWe present the time-resolved ODMR studies of single {(Cd,Mg)Te/(Cd,Mn)Te}\nquantum wells (QWs) with manganese ions located at different positions along\nthe growth axis -- in the center or on the sides of the quantum well. We\nobserve that spin-lattice relaxation of Mn$^{2+}$ significantly depends on the\nion-carrier wavefunction overlap at low-magnetic fields. Interestingly, the\neffect is clearly observed in spite of very low carrier density, which suggests\nthe potential for control of the Mn$^{2+}$ ion relaxation rate by means of the\nelectric field in future experiments."
    },
    {
        "anchor": "Electrical control of interlayer exciton dynamics in atomically thin\n  heterostructures: Excitons in semiconductors, bound pairs of excited electrons and holes, can\nform the basis for new classes of quantum optoelectronic devices. A van der\nWaals heterostructure built from atomically thin semiconducting transition\nmetal dichalcogenides (TMDs) enables the formation of excitons from electrons\nand holes in distinct layers, producing interlayer excitons with large binding\nenergy and a long lifetime. Employing heterostructures of monolayer TMDs, we\nrealize optical and electrical generation of long-lived neutral and charged\ninterlayer excitons. We demonstrate the transport of neutral interlayer\nexcitons across the whole sample that can be controlled by excitation power and\ngate electrodes. We also realize the drift motion of charged interlayer\nexcitons using Ohmic-contacted devices. The electrical generation and control\nof excitons provides a new route for realizing quantum manipulation of bosonic\ncomposite particles with complete electrical tunability.",
        "positive": "Magnetic distillation of intrinsic electric dipoles in mixed-stacking\n  tetralayer graphene: Polytypes of tetralayer graphene (TLG: Bernal, rhombohedral and mixed\nstacking) offer a choice of crystalline structures with different symmetries.\nAmong those, mixed-stacking tetralayers lack inversion symmetry, which allows\nfor intrinsic spontaneous out-of-plane electrical polarisation, inverted in the\nmirror-image pair, ABCB and ABAC stackings. Here, we compare the intrinsic\npolarisation with the symmetry-breaking effect of a substrate. We find that a\npotential induced by the substrate on the bottom layer of the TLG can generate\nout-of-plane electric dipole moments with different sizes in all four polytypes\nand, also, different for the ABCB and ABAC pair. This undermines a\nstraightforward interpretation of experimentally measured Kelvin probe\nmicroscopy maps of tetralayer flakes in terms of their intrinsic polarisation.\nTo overcome this difficulty, we analyse the influence of an external magnetic\nfield on electrical polarisation of all four TLGs and find that Landau level\nquantisation highlights the intrinsic asymmetry of mixed stacking polytypes,\nmaking the difference between ABCB and ABAC polarisations almost independent of\nthe substrate effect. We also notice a non-monotonic (hump-like) feature in the\npolarisation in a magnetic field range of 0.5-3 Tesla, caused by the interplay\nbetween time inversion symmetry breaking and spatial inversion symmetry\nbreaking specific for those two polytypes."
    },
    {
        "anchor": "Quantum oscillations in diamond field effect transistors with a h-BN\n  gate dielectric: Diamond has attracted attention as a next-generation semiconductor because of\nits various exceptional properties such as a wide bandgap and high breakdown\nelectric field. Diamond field effect transistors, for example, have been\nextensively investigated for high-power and high-frequency electronic\napplications. The quality of their charge transport (i.e., mobility), however,\nhas been limited due to charged impurities near the diamond surface. Here, we\nfabricate diamond field effect transistors by using a monocrystalline hexagonal\nboron nitride as a gate dielectric. The resulting high mobility of charge\ncarriers allows us to observe quantum oscillations in both the longitudinal and\nHall resistivities. The oscillations provide important information on the\nfundamental properties of the charge carriers, such as effective mass,\nlifetime, and dimensionality. Our results indicate the presence of a\nhigh-quality two-dimensional hole gas at the diamond surface and thus pave the\nway for studies of quantum transport in diamond and the development of low-loss\nand high-speed devices.",
        "positive": "High magnetic field theory for the local density of states in graphene\n  with smooth arbitrary potential landscapes: We study theoretically the energy and spatially resolved local density of\nstates (LDoS) in graphene at high perpendicular magnetic field. For this\npurpose, we extend from the Schr\\\"odinger to the Dirac case a\nsemicoherent-state Green's-function formalism, devised to obtain in a\nquantitative way the lifting of the Landau-level degeneracy in the presence of\nsmooth confinement and smooth disordered potentials. Our general technique,\nwhich rigorously describes quantum-mechanical motion in a magnetic field beyond\nthe semi-classical guiding center picture of vanishing magnetic length (both\nfor the ordinary two-dimensional electron gas and graphene), is connected to\nthe deformation (Weyl) quantization theory in phase space developed in\nmathematical physics. For generic quadratic potentials of either scalar (i.e.,\nelectrostatic) or mass (i.e., associated with coupling to the substrate) types,\nwe exactly solve the regime of large magnetic field (yet at finite magnetic\nlength - formally, this amounts to considering an infinite Fermi velocity)\nwhere Landau-level mixing becomes negligible. Hence, we obtain a closed-form\nexpression for the graphene Green's function in this regime, providing\nanalytically the discrete energy spectra for both cases of scalar and mass\nparabolic confinement. Furthermore, the coherent-state representation is shown\nto display a hierarchy of local energy scales ordered by powers of the magnetic\nlength and successive spatial derivatives of the local potential, which allows\none to devise controlled approximation schemes at finite temperature for\narbitrary and possibly disordered potential landscapes. As an application, we\nderive general analytical non-perturbative expressions for the LDoS, which may\nserve as a good starting point for interpreting experimental studies."
    },
    {
        "anchor": "Sequential Tunneling through Molecular Spin Rings: We consider electrical transport through molecules with Heisenberg-coupled\nspins arranged in a ring structure in the presence of an easy-axis anisotropy.\nThe molecules are coupled to two metallic leads and a gate. In the charged\nstate of the ring, a Zener double-exchange mechanism links transport properties\nto the underlying spin structure. This leads to a remarkable contact-site\ndependence of the current, which for an antiferromagnetic coupling of the spins\ncan lead to a total suppression of the zero-bias conductance when the molecule\nis contacted at adjacent sites.",
        "positive": "Phase transition between quantum and classical regimes for the escape\n  rate of dimeric molecular nanomagnets in a staggered magnetic field: We study the phase transition of the escape rate of exchange-coupled dimer of\nsingle-molecule magnets which are coupled either ferromagnetic ally or\nantiferromagnetically in a staggered magnetic field and an easy $z$-axis\nanisotropy. The Hamiltonian for this system has been used to study molecular\ndimer nanomagnets [Mn$_4$]$_2$. We generalize the method of mapping a\nsingle-molecule magnetic spin problem onto a quantum-mechanical particle to\ndimeric molecular nanomagnets. The problem is mapped to a single particle\nquantum-mechanical Hamiltonian in terms of the relative coordinate and a\ncoordinate dependent reduced mass. It is shown that the presence of the\nexternal staggered magnetic field creates a phase boundary separating the\nfirst- from the second-order transition. With the set of parameters used by R.\nTiron, $\\textit{et al}$, \\prl {\\bf 91}, 227203 (2003), and S. Hill, $\\textit{et\nal}$ science {\\bf 302}, 1015 (2003) to fit experimental data for [Mn$_{4}$]$_2$\ndimer we find that the critical temperature at the phase boundary is $T^{(c)}_0\n=0.29K$. Therefore, thermally activated transitions should occur for\ntemperatures greater than $T^{(c)}_0$."
    },
    {
        "anchor": "Intraband memory function and memory-function conductivity formula in\n  doped graphene: The generalized self-consistent field method is used to describe intraband\nrelaxation processes in a general multiband electronic system with presumably\nweak residual electron-electron interactions. The resulting memory-function\nconductivity formula is shown to have the same structure as the result of a\nmore accurate approach based on the quantum kinetic equation. The results are\napplied to heavily doped and lightly doped graphene. It is shown that the\nscattering of conduction electron by phonons leads to the redistribution of the\nintraband conductivity spectral weight over a wide frequency range, however, in\na way consistent with the partial transverse conductivity sum rule. The present\nform of the intraband memory function is found to describe correctly the\nscattering by quantum fluctuations of the lattice, at variance with the\nsemiclassical Boltzmann transport equations, where this scattering channel is\nabsent. This is shown to be of fundamental importance in quantitative\nunderstanding of the reflectivity data measured in lightly doped graphene as\nwell as in different low-dimensional strongly correlated electronic systems,\nsuch as the cuprate superconductors.",
        "positive": "Dynamical screening of the Coulomb interaction for two confined\n  electrons in a magnetic field: We show that a difference in time scales of vertical and lateral dynamics\npermits one to analyze the problem of interacting electrons confined in an\naxially symmetric three-dimensional potential with a lateral oscillator\nconfinement by means of the effective two-dimensional Hamiltonian with a\nscreened Coulomb interaction. Using an adiabatic approximation based on\naction-angle variables, we present solutions for the effective charge of the\nCoulomb interaction (screening) for a vertical confinement potential simulated\nby parabolic, square, and triangular wells. While for the parabolic potential\nthe solution for the effective charge is given in a closed anlytical form, for\nthe other cases similar solutions can be easily calculated numerically."
    },
    {
        "anchor": "Fluctuations of Conductance Peak Spacings in the Coulomb Blockade\n  Regime: Role of Electron-Electron Interaction: We study influence of electron-electron interaction on statistics of Coulomb\nblockade peak spacings in disordered quantum dots. It is shown that the\ninteraction combined with fluctuations of eigenfunctions of the Fermi sea,\nenhances the peak spacing fluctuations, in accordance with recent experiments.\nIn addition, account of the spin degrees of freedom leads to a pronounced\nodd-even structure for weak interaction ($e^2/\\epsilon \\ll v_F$); in the\nopposite case ($e^2/\\epsilon \\gtrsim v_F$) this structure is washed out.",
        "positive": "Ballistic transport in graphene beyond linear response: The process of coherent creation of particle - hole excitations by an\nelectric field in graphene is quantitatively described beyond linear response.\nWe calculate the evolution of current density, number of pairs and energy in\nballistic regime for electric field E using the tight binding model. While for\nsmall ballistic flight times the current is linear in E and independent of\ntime, for larger ballistic times the current increases and finally at yet\nlarger times Bloch oscillations set in. It is shown that the number of pairs\nfollows the 2D generalization of the Schwinger's creation rate only on certain\ntime segments with a prefactor different from that obtained using the\nasymptotic formula."
    },
    {
        "anchor": "Detection of basepair mismatches in DNA using graphene based nanopore\n  device: We present an unique way to detect basepair mismatches in DNA leading to\ndifferent epigenetic disorder by the method of nanopore sequencing. Based on a\ntight-binding formulation of graphene nanopore based device, using Greens\nfunction approach we measure the changes in the electronic transport properties\nof the device as we translocate a double-stranded DNA through the nanopore\nembeded in a zigzag graphene nanoribbon. In the present work we not only\nsuccessfully detect the usual AT and GC pairs, but also a set of possible\nmismatches in the complementary base-pairing without any ambiguity. Our\ninvestigation shows that this device can also be used for reliable sequential\ndetection of other biomolecules.",
        "positive": "The valleytronic topological filters in silicene-like inner-edge systems: Inner edge state with spin and valley degrees of freedom is a promising\ncandidate to design a dissipationless device due to the topological protection.\nThe central challenge for the application of inner edge state is to generate\nand modulate the polarized currents. In this work, we discover a new mechanism\nto generate fully valley- and spin-valley-polarized current caused by the Bloch\nwavevector mismatch (BWM). Based on this mechanism, we design some serial-typed\ninner-edge filters. With once of the BWM, the coincident states could be\ndivided into transmitted and reflected modes, which can serve as a valley or\nspin-valley filter. In particular, while with twice of the BWM, the incident\ncurrent is absolutely reflected to support an off state with a specified valley\nand spin, which is different from the gap effect. These findings give rise to a\nnew platform for designing valleytronics and spin-valleytronics."
    },
    {
        "anchor": "Fluctuation induced forces in the presence of mobile carrier drift: A small polarizable object (an atom, molecule or nanoparticle), placed above\na medium with flowing dc current in it, is considered. It is shown that the dc\ncurrent can have a strong effect on the force exerted on the particle. The\nCasimir-Lifshitz force, well studied in the absence of current, gets modified\ndue to drifting mobile carriers in the medium. Furthermore, a force in the\nlateral direction appears. This force is a non-monotonic function of the drift\nvelocity and its maximal value is comparable with the Casimir-Lifshitz force.\nIf the temperatures of the medium and the particle are different, this lateral\nforce can be directed along the current (drag) or in the opposite direction\n(anti-drag).",
        "positive": "Clar's goblet on graphene: field modulated charge transfer in a\n  hydrocarbon heterostructure: In certain configurations, the aromatic properties of benzene ring structured\nmolecules allow for unpaired, reactive valence electrons (known as radicals).\nClar's goblets are such molecules. With an even number of unpaired radicals,\nthese nanographenes are topologically frustrated hydrocarbons in which\npi-bonding network and topology of edges give rise to the magnetism. Clar's\ngoblets are therefore valued as prospective qubits provided they can be\nmodulated between magnetic states. Using first principles DFT, we demonstrate\nthe effects of adsorption on both molecule and substrate in a graphene-Clar's\ngoblet heterostructure. We look at the energy difference bewteen FM and AFM\nstates of the system and discuss underlying physical and chemical mechanisms in\nreference to the highest occupied molecular orbital (HOMO) and second HOMO\n(HOMO-1). We find that the HOMO of the molecule in the FM state is right at the\nFermi surface, which leads to the hybridization between molecular state and the\ngraphene state near the Dirac point. Furthermore, we investigate qualitative\nchanges in charge realignment and magnetic state under variable electric field.\nTransitions from FM to AFM and back to FM states are observed."
    },
    {
        "anchor": "Achiral dipoles on a ferromagnet can affect its magnetization direction: We demonstrate the possibility of a coupling between the magnetization\ndirection of a ferromagnet and the tilting angle of adsorbed achiral molecules.\nTo illustrate the mechanism of the coupling, we analyze a minimal Stoner model\nthat includes Rashba spin-orbit coupling due to the electric field on the\nsurface of the ferromagnet. The proposed mechanism allows us to study magnetic\nanisotropy of the system with an extended Stoner-Wohlfarth model, and argue\nthat adsorbed achiral molecules can change magnetocrystalline anisotropy of the\nsubstrate. Our research's aim is to motivate further experimental studies of\nthe current-free chirality induced spin selectivity effect involving both\nenantiomers.",
        "positive": "Fundamental relation between longitudinal and transverse conductivities\n  in the quantum Hall system: We investigate the relation between the diagonal ($\\sigma_{xx}$) and\noff-diagonal ($\\sigma_{xy}$) components of the conductivity tensor in the\nquantum Hall system. We calculate the conductivity components for a short-range\nimpurity potential using the linear response theory, employing an approximation\nthat simply replaces the self-energy by a constant value $-i \\hbar /(2 \\tau)$\nwith $\\tau$ the scattering time. The approximation is equivalent to assuming\nthat the broadening of a Landau level due to disorder is represented by a\nLorentzian with the width $\\Gamma = \\hbar /(2 \\tau)$. Analytic formulas are\nobtained for both $\\sigma_{xx}$ and $\\sigma_{xy}$ within the framework of this\nsimple approximation at low temperatures. By examining the leading terms in\n$\\sigma_{xx}$ and $\\sigma_{xy}$, we find a proportional relation between\n$\\mathrm{d}\\sigma_{xy}/\\mathrm{d}B$ and $B \\sigma_{xx}^2$. The relation, after\nslight modification to account for the long-range nature of the impurity\npotential, is shown to be in quantitative agreement with experimental results\nobtained in the GaAs/AlGaAs two-dimensional electron system at the low\nmagnetic-field regime where spin splitting is negligibly small."
    },
    {
        "anchor": "Superballistic flow of viscous electron fluid through graphene\n  constrictions: Electron-electron (e-e) collisions can impact transport in a variety of\nsurprising and sometimes counterintuitive ways. Despite strong interest,\nexperiments on the subject proved challenging because of the simultaneous\npresence of different scattering mechanisms that suppress or obscure\nconsequences of e-e scattering. Only recently, sufficiently clean electron\nsystems with transport dominated by e-e collisions have become available,\nshowing behavior characteristic of highly viscous fluids. Here we study\nelectron transport through graphene constrictions and show that their\nconductance below 150 K increases with increasing temperature, in stark\ncontrast to the metallic character of doped graphene. Notably, the measured\nconductance exceeds the maximum conductance possible for free electrons. This\nanomalous behavior is attributed to collective movement of interacting\nelectrons, which 'shields' individual carriers from momentum loss at sample\nboundaries. The measurements allow us to identify the conductance contribution\narising due to electron viscosity and determine its temperature dependence.\nBesides fundamental interest, our work shows that viscous effects can\nfacilitate high-mobility transport at elevated temperatures, a potentially\nuseful behavior for designing graphene-based devices.",
        "positive": "Electronic transport through nuclear-spin-polarization-induced quantum\n  wire: Electron transport in a new low-dimensional structure - the nuclear spin\npolarization induced quantum wire (NSPI QW) is theoretically studied. In the\nproposed system the local nuclear spin polarization creates the effective\nhyperfine field which confines the electrons with the spins opposite to the\nhyperfine field to the regions of maximal nuclear spin polarization. The\ninfluence of the nuclear spin relaxation and diffusion on the electron energy\nspectrum and on the conductance of the quantum wire is calculated and the\nexperimental feasibility is discussed."
    },
    {
        "anchor": "Identifying defect-related quantum emitters in monolayer WSe$_2$: Monolayer transition metal dichalcogenides have recently attracted great\ninterests because the quantum dots embedded in monolayer can serve as optically\nactive single photon emitters. Here, we provide an interpretation of the\nrecombination mechanisms of these quantum emitters through\npolarization-resolved and magneto-optical spectroscopy at low temperature.\nThree types of defect-related quantum emitters in monolayer tungsten diselenide\n(WSe$_2$) are observed, with different exciton g factors of 2.02, 9.36 and\nunobservable Zeeman shift, respectively. The various magnetic response of the\nspatially localized excitons strongly indicate that the radiative recombination\nstems from the different transitions between defect-induced energy levels,\nvalance and conduction bands. Furthermore, the different g factors and\nzero-field splittings of the three types of emitters strongly show that quantum\ndots embedded in monolayer have various types of confining potentials for\nlocalized excitons, resulting in electron-hole exchange interaction with a\nrange of values in the presence of anisotropy. Our work further sheds light on\nthe recombination mechanisms of defect-related quantum emitters and paves a way\ntoward understanding the role of defects in single photon emitters in\natomically thin semiconductors.",
        "positive": "Creation,transport and detection of imprinted magnetic solitons\n  stabilized by spin-polarized current: With the recent proposition of skyrmion utilization in racetrack memories at\nroom temperature, skyrmionics has become a very attractive field. However, for\nthe stability of skyrmions, it is essential to incorporate the\nDzyaloshinskii-Moriya interaction (DMI) and the out-of-plane magnetic field\ninto the system. In this work, we explore a system without these interactions.\nFirst, we propose a controlled way for the creation of magnetic skyrmions and\nskyrmioniums imprinted on a ferromagnetic nanotrack via a nanopatterned\nnanodisk with the magnetic vortex state. Then we investigate the detachment of\nthe imprinted spin textures from the underneath of the nanodisk, as well as its\ntransport by the spin-transfer torque imposed by spin-polarized current pulses\napplied in the nanotrack. A prominent feature of the moving imprinted spin\ntexture is that its topological number Q is oscillating around the averaged\nvalue of Q=0 as if it is a resonant state between the skyrmions with Q= +/- 1\nand the bubble with Q=0. We may call it a resonant magnetic soliton (RMS). A\nRMS moves along a straight line since it is free from the skyrmion Hall effect.\nIn our studied device, the same electrodes are employed to realize the\nimprinted spin texture detachment and its transport. In addition, we have\ninvestigated the interaction between the RMS and a magnetic tunnel junction\nsensor, where the passing of the RMS in the nanotrack can be well detected. Our\nresults would be useful for the development of novel spintronic devices based\non moveable spin textures."
    },
    {
        "anchor": "Quantum Atmospherics for Materials Diagnosis: Symmetry breaking states of matter can transmit symmetry breaking to nearby\natoms or molecular complexes, perturbing their spectra. We calculate one such\neffect, involving the `axion electrodynamics' relevant to topological\ninsulators, quantitatively, and identify a signature for T violating\nsuperconductivity. We provide an operator framework whereby effects of this\nkind can be analyzed systematically.",
        "positive": "Origins of leakage currents on electrolyte-gated graphene field-effect\n  transistors: Graphene field-effect transistors are widely used for development of\nbiosensors. However, certain fundamental questions about details of their\nfunctioning are not fully understood yet. One of these questions is the\npresence of gate (leakage) currents in the electrolyte-gated configuration.\nHere, we report our observations considering causes of this phenomena on\nchemical vapor deposition (CVD) grown graphene. We observed that gate currents\nreflect currents that occur on the transistor surface similarly to a working\nelectrode - counter electrode pair currents in an electrochemical cell. Gate\ncurrents are capacitive when the graphene channel is doped by holes and\nFaradaic when it is doped by electrons in field-effect measurements. The\nFaradaic current is attributed to a reduction of oxygen dissolved in the\naqueous solution and its magnitude increases with each measurement. We employed\ncyclic voltammetry with a redox probe Fc(MeOH)2 to characterize changes of the\ngraphene structure that are responsible for this activation. Collectively, our\nresults reveal that through the course of catalytic oxygen reduction on the\ntransistor's surface more defects appear."
    },
    {
        "anchor": "Imaging of Low Compressibility Strips in the Quantum Hall Liquid: Using Subsurface Charge Accumulation scanning microscopy we image strips of\nlow compressibility corresponding to several integer Quantum Hall filling\nfactors. We study in detail the strips at Landau level filling factors $\\nu =$\n2 and 4. The observed strips appear significantly wider than predicted by\ntheory. We present a model accounting for the discrepancy by considering a\ndisorder-induced nonzero density of states in the cyclotron gap.",
        "positive": "Spin memristive systems: Recently, in addition to the well-known resistor, capacitor and inductor, a\nfourth passive circuit element, named memristor, has been identified following\ntheoretical predictions. The model example used in such case consisted in a\nnanoscale system with coupled ionic and electronic transport. Here, we discuss\na system whose memristive behaviour is based entirely on the electron spin\ndegree of freedom which allows for a more convenient control than the ionic\ntransport in nanostructures. An analysis of time-dependent spin transport at a\nsemiconductor/ferromagnet junction provides a direct evidence of memristive\nbehaviour. Our scheme is fundamentally different from previously discussed\nschemes of memristive devices and broadens the possible range of applications\nof semiconductor spintronics."
    },
    {
        "anchor": "Spin lifetime measurements in GaAsBi thin films: Photoluminescence spectroscopy and Hanle effect measurements are used to\ninvestigate carrier spin dephasing and recombination times in the semiconductor\nalloy GaAsBi as a function of temperature and excitation energy. Hanle effect\nmeasurements reveal the product of g-factor and effective spin dephasing time\n(gTs) ranges from 0.8 ns at 40 K to 0.1 ns at 120 K. The temperature dependence\nof gTs provides evidence for a thermally activated effect, which is attributed\nto hole localization at single Bi or Bi cluster sites below 40 K.",
        "positive": "Realization of Hofstadter's butterfly and a one-way edge mode in a\n  polaritonic system: We present a scheme to generate an artificial gauge field for the system of\nneutral bosons, represented by polaritons in micropillars arranged into a\nsquare lattice. The splitting between the two polarizations of the micropillars\nbreaks the time-reversal symmetry (TRS) and results in the effective\nphase-dependent hopping between cavities. This can allow for engineering a\nnonzero flux on the plaquette, corresponding to an artificial magnetic field.\nChanging the phase, we observe a characteristic Hofstadter's butterfly pattern\nand the appearance of chiral edge states for a finite-size structure. For\nlong-lived polaritons, we show that the propagation of wave packets at the edge\nis robust against disorder. Moreover, given the inherent driven-dissipative\nnature of polariton lattices, we find that the system can exhibit topological\nlasing, recently discovered for active ring cavity arrays. The results point to\na static way to realize artificial magnetic field in neutral spinful systems,\navoiding the periodic modulation of the parameters or strong spin-orbit\ninteraction. Ultimately, the described system can allow for high-power\ntopological single-mode lasing which is robust to imperfections."
    },
    {
        "anchor": "Facile fabrication of suspended as-grown carbon nanotube devices: A simple scalable scheme is reported for fabricating suspended carbon\nnanotube field effect transistors (CNT-FETs) without exposing pristine as-grown\ncarbon nanotubes to subsequent chemical processing. Versatility and ease of the\ntechnique is demonstrated by controlling the density of suspended nanotubes and\nreproducing devices multiple times on the same electrode set. Suspending the\ncarbon nanotubes results in ambipolar transport behavior with negligible\nhysteresis. The Hooges constant of the suspended CNT-FETs (2.6 x 10-3) is about\n20 times lower than for control CNT-FETs on SiO2 (5.6 x 10-2).",
        "positive": "Radiation of the Tunnel Electron on Secondary Center of Recombination: We discuss the photon emission that occurs due to the radiative recombination\nof an electron on a nearby center after tunneling ionization. The model of an\nactive electron is used, and analytical solution to three-dimensional problem\nis obtained. The dependence of the photon emission from a distance between\ncenters of ionization and a recombination, and also the electric field\norientation are investigated. The formulas for probability of recombination\nradiation are derived."
    },
    {
        "anchor": "Spin susceptibility of two-dimensional transition metal dichalcogenides: We have obtained analytical expressions for the q-dependent static spin\nsusceptibility of monolayer transition metal dichalcogenides, considering both\nthe electron-doped and hole-doped cases. Our results are applied to calculate\nspin-related physical observables of monolayer MoS2, focusing especially on\nin-plane/out-of-plane anisotropies. We find that the hole-mediated RKKY\nexchange interaction for in-plane impurity-spin components decays with the\npower law $R^{-5/2}$ as a function of distance $R$, which deviates from the\n$R^{-2}$ power law normally exhibited by a two-dimensional Fermi liquid. In\ncontrast, the out-of-plane spin response shows the familiar $R^{-2}$ long-range\nbehavior. We also use the spin susceptibility to define a collective g-factor\nfor hole-doped MoS2 systems and discuss its density-dependent anisotropy.",
        "positive": "Dynamical Phase Transitions in Topological Insulators: The traditional concept of phase transitions has, in recent years, been\nwidened in a number of interesting ways. The concept of a topological phase\ntransition separating phases with a different ground state topology, rather\nthan phases of different symmetries, has become a large widely studied field in\nits own right. Additionally an analogy between phase transitions, described by\nnon-analyticities in the derivatives of the free energy, and non-analyticities\nwhich occur in dynamically evolving correlation functions has been drawn. These\nare called dynamical phase transitions and one is often now far from the\nequilibrium situation. In these short lecture notes we will give a brief\noverview of the history of these concepts, focusing in particular on the way in\nwhich dynamical phase transitions themselves can be used to shed light on\ntopological phase transitions and topological phases. We will go on to focus,\nfirst, on the effect which the topologically protected edge states, which are\none of the interesting consequences of topological phases, have on dynamical\nphase transitions. Second we will consider what happens in the experimentally\nrelevant situations where the system begins either in a thermal state rather\nthan the ground state, or exchanges particles with an external environment."
    },
    {
        "anchor": "Collective ferromagnetism of artificial square spin ice: We have studied the temperature and magnetic field dependence of the total\nmagnetic moment of large-area permalloy artificial square spin ice arrays. The\ntemperature dependence and hysteresis behavior are consistent with the coherent\nmagnetization reversal expected in the Stoner-Wohlfarth model, with clear\ndeviations due to inter-island interactions at small lattice spacing. Through\nmicromagnetic simulations, we explore this behavior and demonstrate that the\ndeviations result from increasingly complex magnetization reversal at small\nlattice spacing, induced by inter-island interactions, and depending critically\non details of the island shapes. These results establish new means to tune the\nphysical properties of artificial spin ice structures and other interacting\nnanomagnet systems, such as patterned magnetic media.",
        "positive": "Exploring the Photon-Number Distribution of Bimodal Microlasers: A photon-number resolving transition edge sensor (TES) is used to measure the\nphoton-number distribution of two microcavity lasers. The investigated devices\nare bimodal microlasers with similar emission intensity and photon statistics\nwith respect to the photon auto-correlation. Both high-$\\beta$ microlasers show\npartly thermal and partly coherent emission around the lasing threshold. For\nhigher pump powers, the strong mode of microlaser A emits Poissonian\ndistributed photons while the emission of the weak mode is thermal. In\ncontrast, laser B shows a bistability resulting in overlayed thermal and\nPoissonian distributions. While a standard Hanbury Brown and Twiss experiment\ncannot distinguish between simple thermal emission of laser A and the mode\nswitching of laser B, a TES allows us to measure the photon-number distribution\nwhich provides important insight into the underlying emission processes.\nIndeed, our experimental data and its theoretical description by a master\nequation approach show that TESs are capable of revealing subtle effects like\ntemporal mode switching of bimodal microlasers. As such our studies clearly\ndemonstrate the huge benefit and importance of investigating nanophotonic\ndevices via photon-number resolving sensors."
    },
    {
        "anchor": "Helicity sensitive plasmonic teraherts interferometer: Plasmonic interferometry is a rapidly growing area of research with a huge\npotential for applications in terahertz frequency range. In this Letter, we\nexplore a plasmonic interferometer based on graphene Field Effect Transistor\nconnected to specially designed antennas. As a key result, we observe helicity-\nand phase-sensitive conversion of circularly-polarized radiation into dc\nphotovoltage caused by the plasmon-interference mechanism: two plasma waves,\nexcited at the source and drain part of the transistor interfere inside the\nchannel. The helicity sensitive phase shift between these waves is achieved by\nusing an asymmetric antenna configuration. The dc signal changes sign with\ninversion of the helicity. Suggested plasmonic interferometer is capable for\nmeasuring of phase difference between two arbitrary phase-shifted optical\nsignals. The observed effect opens a wide avenue for phase-sensisitve probing\nof plasma wave excitations in two-dimensional materials.",
        "positive": "Electron transport through Aharonov-Bohm interferometer with laterally\n  coupled double quantum dots: We theoretically investigate electron transport through an Aharonov-Bohm\ninterferometer containing laterally coupled double quantum dots. We introduce\nthe indirect coupling parameter $\\alpha$, which characterizes the strength of\nthe coupling via the reservoirs between two quantum dots. $|\\alpha|=1$\nindicates the strongest coupling, where only a single mode contributes to the\ntransport in the system. Two conduction modes exist in a system where\n$|\\alpha|\\neq 1$. The interference effects such as the Fano resonance and the\nAharonov-Bohm oscillation are suppressed as the absolute value of the parameter\n$\\alpha$ decreases from 1. The linear conductance does not depend on the flux\nwhen $\\alpha=0$ since it corresponds to independent coupling of the dots to the\nreservoir modes."
    },
    {
        "anchor": "Heat current anticorrelation effects leading to thermal conductivity\n  reduction in nanoporous Si: Prevailing nanostructuring strategies focus on increasing phonon scattering\nand reducing the mean-free-path of phonons across the spectrum. In nanoporous\nSi materials, for example, boundary scattering reduces thermal conductivity\ndrastically. In this work, we identify an unusual anticorrelated specular\nphonon scattering effect which can result in additional reductions in thermal\nconductivity of up to ~ 80% for specific nanoporous geometries. We further find\nevidence that this effect has its origin in heat trapping between large pores\nwith narrow necks. As the heat becomes trapped between the pores, phonons\nundergo multiple specular reflections such that their contribution to the\nthermal conductivity is partly undone. We find this effect to be wave-vector\ndependent at low temperatures. We use large-scale molecular dynamics\nsimulations, wave packet analysis, as well as an analytical model to illustrate\nthe anticorrelation effect, evaluate its impact on thermal conductivity, and\ndetail how it can be controlled to manipulate phonon transport in nanoporous\nmaterials.",
        "positive": "Dresselhaus spin-orbit interaction in the p-AlGaAs/GaAs/AlGaAs structure\n  with a square quantum well: Surface Acoustic Waves Study: The effect of spin-orbit interaction was studied in a high-quality\n$p$-AlGaAs/GaAs/AlGaAs structure with a square quantum well using acoustic\nmethods. The structure grown on a GaAs (100) substrate was symmetrically doped\nwith carbon on both sides of the quantum well. Shubnikov-de Haas-type\noscillations of the ac conductance of two-dimensional holes were measured. At a\nlow magnetic field $B <$2 T conductance oscillations undergo beating induced by\na spin-orbit interaction. Analysis of the beating character made it possible to\nseparate the conductance contributions from the two heavy holes subbands split\nby the spin-orbit interaction. For each of the subbands the values of the\neffective masses and quantum relaxation times have been determined, and then\nthe energy of the spin-orbit interaction was obtained. The quantum well\nprofile, as well as the small magnitude of the spin-orbit interaction, allowed\nus to conclude that the spin-orbit splitting is governed by the Dresselhaus\nmechanism."
    },
    {
        "anchor": "Optical transition in self-assembled InAs/GaAs quantum lens under high\n  hydrostatic pressure: We present a simulation to characterize the dependence on hydrostatic\npressure for the photoluminescence spectra in self-assembled quantum dots with\nlens shape geometry. We have tested the physical effects of the band offset and\nelectron-hole effective masses on the optical emission in dot lens. The model\ncould be implemented to get qualitative information of the parameters involved\nin the quantum dot or the measured optical properties as function of pressure.",
        "positive": "Theory of nonlinear optical response of ensembles of double quantum dots: We study theoretically the time-resolved four-wave mixing (FWM) response of\nan ensemble of pairs of quantum dots undergoing radiative recombination. At\nshort (picosecond) delay times, the response signal shows beats that may be\ndominated by the subensemble of resonant pairs, which gives access to the\ninformation on the interdot coupling. At longer delay times, the decay of the\nFWM signal is governed by two rates which result from the collective\ninteraction between the two dots and the radiation modes. The two rates\ncorrespond to the subradiant and super-radiant components in the radiative\ndecay. Coupling between the dots enhances the collective effects and makes them\nobservable even when the average energy mismatch between the dots is relatively\nlarge."
    },
    {
        "anchor": "Spin Accumulation in the Extrinsic Spin Hall Effect: The drift-diffusion formalism for spin-polarized carrier transport in\nsemiconductors is generalized to include spin-orbit coupling. The theory is\napplied to treat the extrinsic spin Hall effect using realistic boundary\nconditions. It is shown that carrier and spin diffusion lengths are modified by\nthe presence of spin-orbit coupling and that spin accumulation due to the\nextrinsic spin Hall effect is strongly and qualitatively influenced by boundary\nconditions. Analytical formulas for the spin-dependent carrier recombination\nrates and inhomogeneous spin densities and currents are presented.",
        "positive": "Comments on ``Evidence of Landau Levels and Interactions in Low-Lying\n  Excitations of Composite Fermions ...\" by Dujovne, Pinczuk, Kang, Dennis,\n  Pfeiffer and West, cond-mat/0211022: Dujavne et al suggest that the observed spectra are a result of spin-split\nLandau levels and spin-flip energies reveal composite fermion interactions. We\nfind that the CF effective field formula is incorrect. In fact, CF model is\nindependent of spin so that the interpretations of data by Dujovne et al in\nterms of CF model are incorrect. It may be pointed out that the experimental\nmass of the quasiparticles is several orders of magnitude smaller than the CF\nmass."
    },
    {
        "anchor": "Charge and energy transfer in ac-driven Coulomb-coupled double quantum\n  dots: We study the dynamics of charge and energy currents in a Coulomb-coupled\ndouble quantum dot system, when only one of the two dots is adiabatically\ndriven by a time-periodic gate that modulates its energy level. Although the\nCoulomb coupling does not allow for electron transfer between the dots, it\nenables an exchange of energy between them which induces a time variation of\ncharge in the undriven dot. We describe the effect of electron interactions at\nlow temperature using a time-dependent slave-spin 1 formulation within\nmean-field that efficiently captures the main effects of the strong\ncorrelations as well as the dynamical nature of the driving. We find that the\ncurrents induced in the undriven dot due to the mutual friction between\ninter-dot electrons are same order than those generated in the adiabatically\ndriven dot. Interestingly, up to 43$\\%$ percent of the energy injected by the\nac sources can be transferred from the driven dot to the undriven one. We\ncomplete our analysis by studying the impact of the Coulomb interaction on the\nresistance of the quantum dot that is driven by the gate.",
        "positive": "Magnetic-field asymmetry of electron wave packet transmission in bent\n  channels capacitively coupled to a metal gate: We study the electron wave packet moving through a bent channel. We\ndemonstrate that the packet transmission probability becomes an uneven function\nof the magnetic field when the electron packet is capacitively coupled to a\nmetal plate. The coupling occurs through a non-linear potential which\ntranslates a different kinetics of the transport for opposite magnetic field\norientations into a different potential felt by the scattered electron."
    },
    {
        "anchor": "Universal transport properties of open microwave cavities with and\n  without time-reversal symmetry: We measure the transmission through asymmetric and reflection-symmetric\nchaotic microwave cavities in dependence of the number of attached wave guides.\nFerrite cylinders are placed inside the cavities to break time-reversal\nsymmetry. The phase-breaking properties of the ferrite and its range of\napplicability are discussed in detail. Random matrix theory predictions for the\ndistribution of transmission coefficients T and their energy derivative dT/dE\nare extended to account for absorption. Using the absorption strength as a\nfitting parameter, we find good agreement between universal transmission\nfluctuations predicted by theory and the experimental data.",
        "positive": "The Landau Level of Fragile Topology: We study the Hofstadter butterfly and Landau levels of the twisted bilayer\ngraphene (TBG). We show that the nontrivial fragile topology of the lowest two\nbands near the charge neutral point makes their Hofstadter butterfly\ngenerically connected with higher bands, closing the gap between the first and\nsecond conduction (valence) bands at a certain magnetic flux per unit cell. We\nalso develop a momentum space method for calculating the TBG Hofstadter\nbutterfly, from which we identify three phases where the Hofstadter butterflies\nof the lowest two bands and the higher bands are connected in different ways.\nWe show this leads to a crossing between the $\\nu=4$ Landau fan from the charge\nneutral point and the zero field band gap at one flux per Moir\\'e unit cell,\nwhich corresponds to a magnetic field $25\\theta^2$T (twist angle $\\theta$ in\ndegrees). This provides an experimentally testable feature of the fragile\ntopology. In general, we expect it to be a generic feature that the Hofstadter\nbutterfly of topological bands are connected with the Hofstadter spectra of\nother bands. We further show the TBG band theory with Zeeman splitting being\nthe most sizable splitting could result in Landau fans at the charge neutral\npoint and half fillings near the magic angle, and we predict their variations\nunder an in-plane magnetic field."
    },
    {
        "anchor": "The effect of Coulomb interactions on nonlinear thermovoltage and\n  thermocurrent in quantum dots: In the present work, we theoretically study the nonlinear regime of charge\ntransport through a quantum dot coupled to the source and drain reservoirs. The\ninvestigation is carried out using a nonequilibrium Green's functions formalism\nbeyond the Hartree-Fock approximation. Employed approximations for the relevant\nGreen's functions allow to trace a transition from Coulomb blockade regime to\nKondo regime in the thermoelectric transport. Effects arising when electrons\nmove in response to thermal gradient applied across the system are discussed,\nincluding experimentally observed thermovoltage zeros.",
        "positive": "Manifestation of interdot spin tunneling effects in ordered arrays of\n  quantum dots: An anomalous magnetization of In_{1-x}Mn_xAs: The anomalous low-temperature behavior of the spontaneous magnetization of\nordered arrays of In_{1-x}Mn_xAs quantum dots is discussed. It is shown that\nthe experimental results can be well understood, within a mean field\napproximation, assuming collective response through rather strong spin\ntunneling processes between neighbouring dots."
    },
    {
        "anchor": "Wigner solids of wide quantum wells near Landau filling $\u03bd=1$: Microwave spectroscopy within the Landau filling ($\\nu$) range of the integer\nquantum Hall effect (IQHE) has revealed pinning mode resonances signifying\nWigner solids (WSs) composed of quasi-particles or -holes. We study pinning\nmodes of WSs in wide quantum wells (WQWs) for $ 0.8\\le\\nu\\le1.2$, varying the\ndensity, $n$, and tilting the sample by angle $\\theta$ in the magnetic field.\nThree distinct WS phases are accessed. One phase, S1, is phenomenologically the\nsame as the WS observed in the IQHEs of narrow QWs. The second phase, S2,\nexists at $\\nu$ further from $\\nu=1$ than S1, and requires a sufficiently large\n$n$ or $\\theta$, implying S2 is stabilized by the Zeeman energy. The melting\ntemperatures of S1 and S2, estimated from the disappearance of the pinning\nmode, show different behavior vs $\\nu$. At the largest $n$ or $\\theta$, S2\ndisappears and the third phase, S1A, replaces S1, also exhibiting a pinning\nmode. This occurs as the WQW $\\nu=1$ IQHE becomes a two-component,\nHalperin-Laughlin $\\pone$ state. We interpret S1A as a WS of the excitations of\n$\\pone$, which has not been previously observed.",
        "positive": "Stochastic memory: memory enhancement due to noise: There are certain classes of resistors, capacitors and inductors that, when\nsubject to a periodic input of appropriate frequency, develop hysteresis loops\nin their characteristic response. Here, we show that the hysteresis of such\nmemory elements can also be induced by white noise of appropriate intensity\neven at very low frequencies of the external driving field. We illustrate this\nphenomenon using a physical model of memory resistor realized by\n$\\mathrm{TiO_2}$ thin films sandwiched between metallic electrodes, and discuss\nunder which conditions this effect can be observed experimentally. We also\ndiscuss its implications on existing memory systems described in the literature\nand the role of colored noise."
    },
    {
        "anchor": "Hyperfine-assisted fast electric control of dopant nuclear spins in\n  semiconductors: Nuclear spins of dopant atoms in semiconductors are promising candidates as\nquantum bits, due to the long lifetime of their quantum states. Conventionally,\ncoherent control of nuclear spins is done using ac magnetic fields. Using the\nexample of a phosphorus atom in silicon, we theoretically demonstrate that\nhyperfine interaction can enhance the speed of magnetic control: the electron\non the donor amplifies the ac magnetic field felt by the nuclear spin. Based on\nthat result, we show that hyperfine interaction also provides a means to\ncontrol the nuclear spin efficiently using an ac electric field, in the\npresence of intrinsic or artificial spin-orbit interaction. This electric\ncontrol scheme is especially efficient and noise-resilient in a hybrid\ndot-donor system holding two electrons in the presence of an inhomogeneous\nmagnetic field. The mechanisms proposed here could be used as building blocks\nin nuclear-spin-based electronic quantum information architectures.",
        "positive": "Microwave Photoresistance in dc-driven 2D Systems at Cyclotron Resonance\n  Subharmonics: We study microwave photoresistivity oscillations in a high mobility\ntwo-dimensional electron system subject to strong dc electric fields. We find\nthat near the second subharmonic of the cyclotron resonance the frequency of\nthe resistivity oscillations with dc electric field is twice the frequency of\nthe oscillations at the cyclotron resonance, its harmonics, or in the absence\nof microwave radiation. This observation is discussed in terms of the\nmicrowave-induced sidebands in the density of states and the interplay between\ndifferent scattering processes in the separated Landau level regime."
    },
    {
        "anchor": "Focused Crossed Andreev Reflection: We consider non-local transport in a system with one superconducting and two\nnormal metal terminals. Electron focusing by weak perpendicular magnetic fields\nis shown to tune the ratio between crossed Andreev reflection (CAR) and\nelectron transfer (ET) in the non-local current response. Additionally,\nelectron focusing facilitates non-local signals between normal metal contacts\nwhere the separation is as large as the mean free path rather than being\nlimited by the coherence length of the superconductor. CAR and ET can be\nselectively enhanced by modulating the magnetic field.",
        "positive": "Kinetic investigation on extrinsic spin Hall effect induced by skew\n  scattering: The kinetics of the extrinsic spin Hall conductivity induced by the skew\nscattering is performed from the fully microscopic kinetic spin Bloch equation\napproach in $(001)$ GaAs symmetric quantum well. In the steady state, the\nextrinsic spin Hall current/conductivity vanishes for the linear-$\\mathbf k$\ndependent spin-orbit coupling and is very small for the cubic-$\\mathbf k$\ndependent spin-orbit coupling. The spin precession induced by the\nDresselhaus/Rashba spin-orbit coupling plays a very important role in the\nvanishment of the extrinsic spin Hall conductivity in the steady state. An\nin-plane spin polarization is induced by the skew scattering, with the help of\nthe spin-orbit coupling. This spin polarization is very different from the\ncurrent-induced spin polarization."
    },
    {
        "anchor": "Hyperfine interaction mediated exciton spin relaxation in (In,Ga)As\n  quantum dots: The population dynamics of dark and bright excitons in (In,Ga)As/GaAs quantum\ndots is studied by two-color pump-probe spectroscopy in an external magnetic\nfield. With the field applied in Faraday geometry and at T<20 K, the dark\nexcitons decay on a ten nanoseconds time scale unless the magnetic field\ninduces a resonance with a bright exciton state. At these crossings their\neffective lifetime is drastically shortened due to spin flips of either\nelectron or hole by which the dark excitons are converted into bright ones. Due\nto the quasielastic character we attribute the origin of these flips to the\nhyperfine interaction with the lattice nuclei. We compare the exciton spin\nrelaxation times in the two resonances and find that the spin flip involving an\nelectron is approximately 25 times faster than the one of the hole. A\ntemperature increase leads to a considerable, nonmonotonic decrease of the dark\nexciton lifetime. Here phonon-mediated spin flips due to the spin-orbit\ninteraction gradually become more important.",
        "positive": "Electrical resistance of individual defects at a topological insulator\n  surface: Three-dimensional topological insulators host surface states with linear\ndispersion, which manifest as a Dirac cone. Nanoscale transport measurements\nprovide direct access to the transport properties of the Dirac cone in real\nspace and allow the detailed investigation of charge carrier scattering. Here,\nwe use scanning tunnelling potentiometry to analyse the resistance of different\nkinds of defects at the surface of a (Bi0.53Sb0.47)2Te3 topological insulator\nthin film. The largest localized voltage drop we find to be located at domain\nboundaries in the topological insulator film, with a resistivity about four\ntimes higher than that of a step edge. Furthermore, we resolve resistivity\ndipoles located around nanoscale voids in the sample surface. The influence of\nsuch defects on the resistance of the topological surface state is analysed by\nmeans of a resistor network model. The effect resulting from the voids is found\nto be small compared to the other defects."
    },
    {
        "anchor": "Intervalley biexcitons and many-body effects in monolayer MoS2: Interactions between two excitons can result in the formation of bound\nquasiparticles, known as biexcitons. Their properties are determined by the\nconstituent excitons, with orbital and spin states resembling those of atoms.\nMonolayer transition metal dichalcogenides (TMDs) present a unique system where\nexcitons acquire a new degree of freedom, the valley pseudospin, from which a\nnovel intervalley biexciton can be created. These biexcitons comprise two\nexcitons from different valleys, which are distinct from biexcitons in\nconventional semiconductors and have no direct analogue in atomic and molecular\nsystems. However, their valley properties are not accessible to traditional\ntransport and optical measurements. Here, we report the observation of\nintervalley biexcitons in the monolayer TMD MoS2 using ultrafast pump-probe\nspectroscopy. By applying broadband probe pulses with different helicities, we\nidentify two species of intervalley biexcitons with large binding energies of\n60 meV and 40 meV. In addition, we also reveal effects beyond biexcitonic\npairwise interactions in which the exciton energy redshifts at increasing\nexciton densities, indicating the presence of many-body interactions among\nthem.",
        "positive": "Helical Majorana fermions at the interface of Weyl semimetal and d-wave\n  superconductor: Application to Iridates and high-Tc Cuprates: Majorana bound states exist inside a core of half-quantum vortex in\nspin-triplet superconductors. Despite intense efforts, they have not been\ndiscovered in any spin-triplet superconductor candidate materials. After the\nsuccess of topological insulator, another route to achieve Majorana fermions\nhas been suggested: heterostructures of s-wave superconductors and topological\ninsulator or semimetal with strong spin-orbit coupling provide an effective\nspinless $p+ip$ pairing which supports Majorana bound states in a single\nvortex. This theoretical observation has stimulated both experimental and\ntheoretical communities to search for Majorana fermions, and recently a\nlocalized Majorana state at the end of one-dimensional wire has been reported.\nHere we study the two-dimensional interface of Weyl semimetal and d-wave\nsuperconductor which promotes a pair of helical Majorana fermions propagating\nalong the edge of the interface. We suggest that Iridium oxide layer IrO$_2$\nclassified as two-dimensional Weyl semimetal in close proximity to high\ntemperature Cuprates would be a best example to explore these helical Majorana\nmodes."
    },
    {
        "anchor": "Ground state structure and conductivity of quantum wires of infinite\n  length and finite width: We have studied the ground state structure of quantum strips within the local\nspin-density approximation, for a range of electronic densities between $\\sim$\n5$\\times10^4$ and 2$\\times10^6$ cm$^{-1}$ and several strengths of the lateral\nconfining potential. The results have been used to address the conductance $G$\nof quantum strips. At low density, when only one subband is occupied, the\nsystem is fully polarized and $G$ takes a value which is close to\n0.7(2e$^2/h$), decreasing with increasing electron density in agreement with\nexperiments. At higher densities the system becomes paramagnetic and $G$ takes\na value near (2e$^2/h$), showing a similar decreasing behaviour with increasing\nelectron density. In both cases, the physical parameter that determines the\nvalue of the conductance is the ratio $K/K_0$ of the compressibility of the\nsystem over the free one.",
        "positive": "Fine structure of negatively charged and neutral excitons in monolayer\n  MoS$_{2}$: We present experimental and theoretical results on the high-quality\nsingle-layer MoS$_{2}$ which reveal the fine structure of charged excitons,\ni.e., trions. In the emission spectra we resolve and identify two trion peaks,\nT$_{1}$ and T$_{2}$, resembling the pair of singlet and triplet trion peaks\n(T$_S$ and T$_{T}$) in tungsten-based materials. However, in\npolarization-dependent photoluminescence measurements we identify these peaks\nas novel intra- and inter-valley singlet trions, constituting the trion fine\nstructure distinct from that already known in bright and dark 2D materials with\nlarge conduction-band splitting induced by the spin-orbit coupling. We show\nthat the trion energy splitting in MoS$_{2}$ is a sensitive probe of inter- and\nintra-valley carrier interaction. With additional support from theory we claim\nthat the existence of these singlet trions combined with an anomalous excitonic\ng-factor and the characteristic temperature dependence of the emission spectra\ntogether suggest that monolayer MoS$_{2}$ has a dark excitonic ground state,\ndespite having \"bright\" single-particle arrangement of spin-polarized\nconduction bands."
    },
    {
        "anchor": "New Quantum Transition in Weyl Semimetals with Correlated Disorder: A Weyl semimetal denotes an electronic phase of solids in which two bands\ncross linearly. In this paper we study the effect of a spatially correlated\ndisorder on such a phase. Using a renormalization group analysis, we show that\nin three dimensions, three scenarios are possible depending on the disorder\ncorrelations. A standard transition is recovered for short range correlations.\nFor disorder decaying slower than $1/r^{2}$, the Weyl semimetal is unstable to\nany weak disorder and no transition persists. In between, a new phase\ntransition occurs. This transition still separates a disordered metal from a\nsemi-metal, but with a new critical behavior that we analyze to two-loop order.",
        "positive": "Ultrafast dephasing of light in strongly scattering GaP nanowires: We demonstrate ultrafast dephasing in the random transport of light through a\nlayer consisting of strongly scattering GaP nanowires. Dephasing results in a\nnonlinear intensity modulation of individual pseudomodes which is 100 times\nlarger than that of bulk GaP. Different contributions to the nonlinear response\nare separated using total transmission, white-light frequency correlation, and\nstatistical pseudomode analysis. A dephasing time of $1.2\\pm 0.2$~ps is found.\nQuantitative agreement is obtained with numerical model calculations which\ninclude photoinduced absorption and deformation of individual scatterers.\nNonlinear dephasing of photonic eigenmodes opens up avenues for ultrafast\ncontrol of random lasers, nanophotonic switches, and photon localization."
    },
    {
        "anchor": "On testing the violation of the Clausius inequality in nanoscale\n  electric circuits: The Clausius inequality, one of the classical formulations of the second law,\nwas recently found to be violated in the quantum regime. Here this result is\nformulated in the context of a mesoscopic or nanoscale linear RLC circuit\ninteracting with a thermal bath. Previous experiments in this and related\nfields are analyzed and possibilities of experimental detection of the\nviolation are pointed out. It is discussed that recent experiments reached the\nrange of temperatures, where the effect should be visible, and that a part of\nthe proposal was already confirmed.",
        "positive": "Magnonic crystals - prospective structures for shaping spin waves in\n  nanoscale: We have investigated theoretically band structure of spin waves in magnonic\ncrystals with periodicity in one-(1D), two- (2D) and three-dimensions (3D). We\nhave solved Landau-Lifshitz equation with the use of plane wave method, finite\nelement method in frequency domain and micromagnetic simulations in time domain\nto find the dynamics of spin waves and spectrum of their eigenmodes. The spin\nwave spectra were calculated in linear approximation. In this paper we show\nusefulness of these methods in calculations of various types of spin waves. We\ndemonstrate the surface character of the Damon-Eshbach spin wave in 1D magnonic\ncrystals and change of its surface localization with the band number and\nwavenumber in the first Brillouin zone. The surface property of the spin wave\nexcitation is further exploited by covering plate of the magnonic crystal with\nconductor. The band structure in 2D magnonic crystals is complex due to\nadditional spatial inhomogeneity introduced by the demagnetizing field. This\nmodifies spin wave dispersion, makes the band structure of magnonic crystals\nstrongly dependent on shape of the inclusions and type of the lattice. The\ninhomogeneity of the internal magnetic field becomes unimportant for magnonic\ncrystals with small lattice constant, where exchange interactions dominate. For\n3D magnonic crystals, characterized by small lattice constant, wide magnonic\nband gap is found. We show that the spatial distribution of different materials\nin magnonic crystals can be explored for tailored effective damping of spin\nwaves."
    },
    {
        "anchor": "Gate voltage induced injection and shift currents in AA- and AB-stacked\n  bilayer graphene: Generating photogalvanic effects in centrosymmetric materials can provide new\nopportunities for developing passive photodetectors and energy harvesting\ndevices. In this work, we investigate the photogalvanic effects in\ncentrosymmetric two-dimensional materials, AA- and AB-stacked bilayer graphene,\nby applying an external gate voltage to break the symmetry. Using a\ntight-binding model to describe the electronic states, the injection\ncoefficients for circular photogalvanic effects and shift conductivities for\nlinear photogalvanic effects are calculated for both materials with light\nwavelengths ranging from THz to visible. We find that gate voltage induced\nphotogalvanic effects can be very significant for AB-stacked bilayer graphene,\nwith generating a maximal dc current in the order of mA for a 1 $\\mu$m wide\nsample illuminated by a light intensity of 0.1 GW/cm$^2$, which is determined\nby the optical transition around the band gap and van Hove singularity points.\nAlthough such effects in AA-stacked bilayer graphene are about two orders of\nmagnitude smaller than those in AB-stacked bilayer graphene, the spectrum is\ninterestingly limited in a very narrow photon energy window, which is\nassociated with the interlayer coupling strength. A detailed analysis of the\nlight polarization dependence is also performed. The gate voltage and chemical\npotential can be used to effectively control the photogalvanic effects.",
        "positive": "Magnetization reversal using excitation of collective modes in nanodot\n  matrices: The large arrays of magnetic dots are the building blocks of magnonic\ncrystals and the emerging bit patterned media for future recording technology.\nIn order to fully utilize the functionalities of high density magnetic\nnanodots, a method for the selective reversal of a single nanodot in a matrix\nof dots is desired. We have proposed a method for magnetization reversal of a\nsingle nanodot with microwave excitation in a matrix of magneto-statically\ninteracting dots. The method is based on the excitation of collective modes and\nthe spatial anomaly in the microwave power absorption. We perform numerical\nsimulations to demonstrate the possibility of switching a single dot from any\ninitial state of a 3 by 3 matrix of dots, and develop a theoretical model for\nthe phenomena. We discuss the applicability of the proposed method for\nintroducing defect modes in magnonic crystals as well as for future magnetic\nrecording."
    },
    {
        "anchor": "Position-dependent stochastic diffusion model of ion channel gating: A position-dependent stochastic diffusion model of gating in ion channels is\ndeveloped by considering the spatial variation of the diffusion coefficient\nbetween the closed and open states. It is assumed that a sensor which regulates\nthe opening of the ion channel experiences Brownian motion in a closed region\n$R_{c}$ and a transition region $R_{m}$, where the dynamics is described by\nprobability densities $p_{c}(x,t)$ and $p_{m}(x,t)$ which satisfy interacting\nFokker-Planck equations with diffusion coefficient\n$D_{c}(x)=D_{c}\\exp(\\gamma_{c}x)$ and $D_{m}(x)=D_{m} \\exp(-\\gamma_{m}x)$. The\nanalytical solution of the coupled equations may be approximated by the lowest\nfrequency relaxation, a short time after the application of a depolarizing\nvoltage clamp, when $D_{m} \\ll D_{c}$ or the diffusion parameter $\\gamma_{m}$\nis sufficiently large. Thus, an empirical rate equation that describes gating\ntransitions may be derived from a stochastic diffusion model if there is a\nlarge diffusion (or potential) barrier between open and closed states.",
        "positive": "Spin torque and waviness in magnetic multilayers: a bridge between\n  Valet-Fert theory and quantum approaches: We develop a simple theoretical framework for transport in magnetic\nmultilayers, based on Landauer-Buttiker scattering formalism and Random Matrix\nTheory. A simple transformation allows one to go from the scattering point of\nview to theories expressed in terms of local currents and electrochemical\npotential. In particular, our theory can be mapped onto the well established\nclassical Valet Fert theory for collinear systems. For non collinear systems,\nin the absence of spin-flip scattering, our theory can be mapped onto the\ngeneralized circuit theory. We apply our theory to the angular dependance of\nspin accumulation and spin torque in non-collinear spin valves."
    },
    {
        "anchor": "Spinor Stochastic Resonance: We report on noise-induced-spin-ordering in a collective quasipaticle system:\nspinor stochastic resonance. Synergetic interplay of a polarization-modulated\nsignal and a polarization-noise allows us to switch coherently between the two\nmetastable states of a microcavity-polariton spin bistable system. Spinor\nstochastic resonance is demonstrated in a zero-dimensional GaAs based\nmicrocavity. The resonance behavior of both the spin amplification and the\nsignal-to-noise ratio are experimentally evidenced as a function of the noise\nstrength for different amplitude modulations. They are theoretically reproduced\nusing a spinor- Gross-Pitaevskii equation driven by a randomly polarized laser\nfield.",
        "positive": "Effects of interband transitions on Faraday rotation in metallic\n  nanoparticles: The Faraday rotation in metallic nanoparticles is considered based on a\nquantum model for the dielectric function \\epsilon(\\omega) in the presence of a\nDC magnetic field B. We focus on effects in \\epsilon(\\omega) due to interband\ntransitions (IBTs), which are important in the blue and ultraviolet for noble\nmetals used in plasmonics. The dielectric function is found using the\nperturbation of the electron density matrix due to the optical field of\nincident electromagnetic radiation. The calculation is applied to transitions\nbetween two bands (d and p, for example) separated by a gap, as one finds in\ngold at the L-point of the Fermi surface. The result of the DC magnetic field\nis a shift in the effective optical frequency causing IBTs by $\\pm \\mu_B B /\n\\hbar$, where opposite signs are associated with left/right circular\npolarizations. Faraday rotation for a dilute solution of 17 nm diameter gold\nnanoparticles is measured and compared with both the IBT theory and a simpler\nDrude model for the bound electron response. Effects of the plasmon resonance\nmode on Faraday rotation in nanoparticles are also discussed."
    },
    {
        "anchor": "Triggering spin reversal in nanomolecules and nanoclusters on demand: Spin reversal in magnetic nanomolecules and nanoclusters is considered. A\nmethod is suggested allowing, from one side, to keep for long time magnetic\npolarization in a metastable state and, from the other side, for starting the\nreversal process at any required time. This method can find applications for\nthe operation of storage memory devices and for the regulation of processes in\nspintronics.",
        "positive": "Non-linear effects in the cyclotron resonance of a massless\n  quasi-particle in graphene: We consider the classical motion of a massless quasi-particle in a magnetic\nfield and under a weak electromagnetic radiation with the frequency $\\omega$.\nDue to the non-parabolic, linear energy dispersion, the particle responds not\nonly at the frequency $\\omega$ but generates a broad frequency spectrum around\nit. The linewidth of the cyclotron resonance turns out to be very broad even in\na perfectly pure material which allows one to explain recent experimental data\nin graphene. It is concluded that the linear response theory does not work in\ngraphene in finite magnetic fields."
    },
    {
        "anchor": "Non-destructive measurement of electron spins in a quantum dot: We propose and implement a non-destructive measurement that distinguishes\nbetween two-electron spin states in a quantum dot. In contrast to earlier\nexperiments with quantum dots, the spins are left behind in the state\ncorresponding to the measurement outcome. By measuring the spin states twice\nwithin a time shorter than the relaxation time, T1, correlations between\nconsecutive measurements are observed. They disappear as the wait time between\nmeasurements become comparable to T1. The correlation between the\npost-measurement state and the measurement outcome is measured to be ~90% on\naverage.",
        "positive": "Topological Effects on Quantum Phase Slips in Superfluid Spin Transport: We theoretically investigate effects of quantum fluctuations on superfluid\nspin transport through easy-plane quantum antiferromagnetic spin chains in the\nlarge-spin limit. Quantum fluctuations give rise to decaying of spin\nsupercurrent by unwinding the magnetic order parameter within the easy plane,\nwhich is referred to as phase slips. We show that the topological term in the\nnonlinear sigma model for the spin chains qualitatively differentiates decaying\nrate of the spin supercurrent between integer spin and half-odd-integer spin\nchains. An experimental setup for a magnetoelectric circuit is proposed, in\nwhich the dependence of the decaying rate on constituent spins can be verified\nby measuring nonlocal magnetoresistance."
    },
    {
        "anchor": "Transport in two dimensional periodic magnetic fields: Ballistic transport properties in a two dimensional electron gas are studied\nnumerically, where magnetic fields are perpendicular to the plane of two\ndimensional electron systemsand periodically modulated both in $x$ and $y$\ndirections. We show that there are three types of trajectories of classical\nelectron motions in this system; chaotic, pinned and runaway trajectories. It\nis found that the runaway trajectories can explain the peaks of\nmagnetoresistance as a function of external magnetic fields, which is believed\nto be related to the commensurability effect between the classical cyclotron\ndiameter and the period of magnetic modulation. The similarity with and\ndifference from the results in the antidot lattice are discussed.",
        "positive": "Phenomenological plasmon broadening and relation to the dispersion: Pragmatic ways of including lifetime broadening of collective modes in the\nelectron liquid are critically compared. Special focus lies on the impact of\nthe damping parameter onto the dispersion. It is quantitatively exemplified for\nthe two-dimensional case, for both, the charge (`sheet'-)plasmon and the\nspin-density plasmon. The predicted deviations fall within the resolution\nlimits of advanced techniques."
    },
    {
        "anchor": "Anomalous temperature dependence of the supercurrent through a chaotic\n  Josephson junction: We calculate the supercurrent through a Josephson junction consisting of a\nphase-coherent metal particle (quantum dot), weakly coupled to two\nsuperconductors. The classical motion in the quantum dot is assumed to be\nchaotic on time scales greater than the ergodic time $\\tau_{erg}$, which itself\nis much smaller than the mean dwell time $\\tau_{dwell}$. The excitation\nspectrum of the Josephson junction has a gap $E_{gap}$, which can be less than\nthe gap $\\Delta$ in the bulk superconductors. The average supercurrent is\ncomputed in the ergodic regime $\\tau_{erg} \\ll \\hbar/\\Delta$, using\nrandom-matrix theory, and in the non-ergodic regime $\\tau_{erg} \\gg\n\\hbar/\\Delta$, using a semiclassical relation between the supercurrent and\ndwell-time distribution. In contrast to conventional Josephson junctions,\nraising the temperature above the excitation gap does not necessarily lead to\nan exponential suppression of the supercurrent. Instead, we find a temperature\nregime between $E_{gap}$ and $\\Delta$ where the supercurrent decreases\nlogarithmically with temperature. This anomalously weak temperature dependence\nis caused by long-range correlations in the excitation spectrum, which extend\nover an energy range $\\hbar/\\tau_{erg}$ greater than $E_{gap} \\simeq\n\\hbar/\\tau_{dwell}$. A similar logarithmic temperature dependence of the\nsupercurrent was discovered by Aslamazov, Larkin, and Ovchinnikov, in a\nJosephson junction consisting of a disordered metal between two tunnel\nbarriers.",
        "positive": "Weyl and Dirac semimetals with Z_2 topological charge: We study the stability of gap-closing (Weyl or Dirac) points in the\nthree-dimensional Brillouin zone of semimetals using Clifford algebras and\ntheir representation theory. We show that a pair of Weyl points with\n$\\mathbb{Z}_2$ topological charge are stable in a semimetal with time-reversal\nand reflection symmetries when the square of the product of the two symmetry\ntransformations equals minus identity. We present toy models of $\\mathbb{Z}_2$\nWeyl semimetals which have surface modes forming helical Fermi arcs. We also\nshow that Dirac points with $\\mathbb{Z}_2$ topological charge are stable in a\nsemimetal with time-reversal, inversion, and SU(2) spin rotation symmetries\nwhen the square of the product of time-reversal and inversion equals plus\nidentity. Furthermore, we briefly discuss the topological stability of point\nnodes in superconductors using Clifford algebras."
    },
    {
        "anchor": "Modular Arithmetic with Nodal Lines: Drumhead Surface States in ZrSiTe: We study the electronic structure of the nodal line semimetal ZrSiTe both\nexperimentally and theoretically. We find two different surface states in\nZrSiTe - topological drumhead surface states and trivial floating band surface\nstates. Using the spectra of Wilson loops, we show that a non-trivial Berry\nphase that exists in a confined region within the Brillouin Zone gives rise to\nthe topological drumhead-type surface states. The $\\mathbb{Z}_2$ structure of\nthe Berry phase induces a $\\mathbb{Z}_2$ 'modular arithmetic' of the surface\nstates, allowing surface states deriving from different nodal lines to\nhybridize and gap out, which can be probed by a set of Wilson loops. Our\nfindings are confirmed by \\textit{ab-initio} calculations and angle-resolved\nphotoemission experiments, which are in excellent agreement with each other and\nthe topological analysis. This is the first complete characterization of\ntopological surface states in the family of square-net based nodal line\nsemimetals and thus fundamentally increases the understanding of the\ntopological nature of this growing class of topological semimetals.",
        "positive": "A technique to directly excite Luttinger liquid collective modes in\n  carbon nanotubes at GHz frequencies: We present a technique to directly excite Luttinger liquid collective modes\nin carbon nanotubes at GHz frequencies. By modeling the nanotube as a\nnano-transmission line with distributed kinetic and magnetic inductance as well\nas distributed quantum and electrostatic capacitance, we calculate the complex,\nfrequency dependent impedance for a variety of measurement geometries. Exciting\nvoltage waves on the nano-transmission line is equivalent to directly exciting\nthe yet-to-be observed one dimensional plasmons, the low energy excitation of a\nLuttinger liquid. Our technique has already been applied to 2d plasmons and\nshould work well for 1d plasmons. Tubes of length 100 microns must be grown for\nGHz resonance frequencies. Ohmic contact is not necessary with our technique;\ncapacitive contacts can work."
    },
    {
        "anchor": "Atomically thin p-n junctions based on two-dimensional materials: Recent research in two-dimensional (2D) materials has boosted a renovated\ninterest in the p-n junction, one of the oldest electrical components which can\nbe used in electronics and optoelectronics. 2D materials offer remarkable\nflexibility to design novel p-n junction device architectures, not possible\nwith conventional bulk semiconductors. In this Review we thoroughly describe\nthe different 2D p-n junction geometries studied so far, focusing on vertical\n(out-of-plane) and lateral (in-plane) 2D junctions and on mixed-dimensional\njunctions. We discuss the assembly methods developed to fabricate 2D p-n\njunctions making a distinction between top-down and bottom-up approaches. We\nalso revise the literature studying the different applications of these\natomically thin p-n junctions in electronic and optoelectronic devices. We\ndiscuss experiments on 2D p-n junctions used as current rectifiers,\nphotodetectors, solar cells and light emitting devices. The important\nelectronics and optoelectronics parameters of the discussed devices are listed\nin a table to facilitate their comparison. We conclude the Review with a\ncritical discussion about the future outlook and challenges of this incipient\nresearch field.",
        "positive": "Breakdown Current Density in BN-Capped Quasi-1D TaSe3 Metallic\n  Nanowires: Prospects of Interconnect Applications: We report results of investigation of the current-carrying capacity of\nnanowires made from the quasi-1D van der Waals metal tantalum triselenide\ncapped with quasi-2D boron nitride. The chemical vapor transport method\nfollowed by chemical and mechanical exfoliation were used to fabricate mm-long\nTaSe3 wires with lateral dimensions in the 20 to 70 nm range. Electrical\nmeasurements establish that TaSe3/h-BN nanowire heterostructures have a\nbreakdown current density exceeding 10 MA/cm2 - an order-of-magnitude higher\nthan that in copper. Some devices exhibited an intriguing step-like breakdown,\nwhich can be explained by the atomic thread bundle structure of the nanowires.\nThe quasi-1D single crystal nature of TaSe3 results in low surface roughness\nand the absence of grain boundaries; these features potentially can enable the\ndownscaling of these wires to lateral dimensions in the few-nm range. These\nresults suggest that quasi-1D van der Waals metals have potential for\napplications in the ultimately downscaled local interconnects."
    },
    {
        "anchor": "Room Temperature Dynamics of an Optically Addressable Single Spin in\n  Hexagonal Boron Nitride: Hexagonal boron nitride (h-BN) hosts pure single-photon emitters that have\nshown evidence of optically detected electronic spin dynamics. However, the\nelectrical and chemical structure of these optically addressable spins is\nunknown, and the nature of their spin-optical interactions remains mysterious.\nHere, we use time-domain optical and microwave experiments to characterize a\nsingle emitter in h-BN exhibiting room temperature optically detected magnetic\nresonance. Using dynamical simulations, we constrain and quantify transition\nrates in the model, and we design optical control protocols that optimize the\nsignal-to-noise ratio for spin readout. This constitutes a necessary step\ntowards quantum control of spin states in h-BN.",
        "positive": "Biexciton oscillator strength: Our goal is to provide a physical understanding of the elementary coupling\nbetween photon and biexciton and to derive the physical characteristics of the\nbiexciton oscillator strength, following the procedure we used for trion.\nInstead of the more standard two-photon absorption, this work concentrates on\nmolecular biexciton created by photon absorption in an exciton gas. We first\ndetermine the appropriate set of coordinates in real and momentum spaces to\ndescribe one biexciton as two interacting excitons. We then turn to second\nquantization and introduce the \"Fourier transform in the exciton sense\" of the\nbiexciton wave function which is the relevant quantity for oscillator strength.\nWe find that, like for trion, the oscillator strength for the formation of one\nbiexciton out of one photon plus a \\emph{single} exciton is extremely small: it\nis one biexciton volume divided by one sample volume smaller than the exciton\noscillator strength. However, due to their quantum nature, trion and biexciton\nhave absorption lines which behave quite differently. Electrons and trions are\nfermionic particles impossible to pile up all at the same energy. This would\nmake the weak trion line spread with electron density, the peak structure only\ncoming from singular many-body effects. By contrast, the bosonic nature of\nexciton and biexciton makes the biexciton peak mainly rise with exciton\ndensity, this rise being simply linear if we forget many-body effects between\nthe photocreated exciton and the excitons present in the sample."
    },
    {
        "anchor": "Environmental, Thermal, and Electrical Susceptibility of Black\n  Phosphorus Field Effect Transistors: Atomic layers of black phosphorus (P) isolated from its layered bulk make a\nnew two-dimensional (2D) semiconducting crystal with sizable direct bandgap,\nhigh carrier mobility, and promises for 2D electronics and optoelectronics.\nHowever, the integrity of black P crystal could be susceptible to a number of\nenvironmental variables and processes, resulting in degradation in device\nperformance even before the device optical image suggests so. Here, we perform\na systematic study of the environmental effects on black P electronic devices\nthrough continued measurements over a month under a number of controlled\nconditions, including ambient light, air, and humidity, and identify evolution\nof device performance under each condition. We further examine effects of\nthermal and electrical treatments on inducing morphology and, performance\nchanges and failure modes in black P devices. The results suggest that\nprocedures well established for nanodevices in other 2D materials may not\ndirectly apply to black P devices, and improved procedures need to be devised\nto attain stable device operation.",
        "positive": "Conductance interference in a superconducting Coulomb blockaded Majorana\n  ring: By tuning the magnetic flux, the two ends of a 1D topological superconductor\nweakly coupled to a normal metal as a ring-shaped junction can host split\nMajorana zero modes (MZMs). When this ring geometry becomes Coulomb blockaded,\nand the two leads come into contact with the two wire ends, the current moves\nthrough the superconductor or the normal metal as an interferometer. The\ntwo-terminal interference conductance can be experimentally measured as a\nfunction of gate voltage and magnetic flux through the ring. However, a $4\\pi$\nperiodicity in the conductance-phase relation (often considered the hallmark of\nMZMs), which can arise both in a topological superconductor and in a trivial\nmetal, cannot establish the existence of MZMs. We show that the trivial metal\nphase can be ruled out in favor of a topological superconductor by studying\npersistent conductance distribution patterns. In particular, in the presence of\nMZMs, the conductance peak spacings of the Coulomb blockaded junction would\nmanifest line crossings as the magnetic flux varies. The locations of the line\ncrossings can distinguish line crossings stemming from the trivial metal."
    },
    {
        "anchor": "Multiplexed Charge-locking Device for Large Arrays of Quantum Devices: We present a method of forming and controlling large arrays of gate-defined\nquantum devices. The method uses a novel, on-chip, multiplexed charge-locking\nsystem and helps to overcome the restraints imposed by the number of wires\navailable in cryostat measurement systems. Two device innovations are\nintroduced. Firstly, a multiplexer design which utilises split gates to allow\nthe multiplexer to divide three or more ways at each branch. Secondly we\ndescribe a device architecture that utilises a multiplexer-type scheme to lock\ncharge onto gate electrodes. The design allows access to and control of gates\nwhose total number exceeds that of the available electrical contacts and\nenables the formation, modulation and measurement of large arrays of quantum\ndevices. We fabricate devices utilising these innovations on n-type GaAs/AlGaAs\nsubstrates and investigate the stability of the charge locked on to the gates.\nProof-of-concept is shown by measurement of the Coulomb blockade peaks of a\nsingle quantum dot formed by a floating gate in the device. The floating gate\nis seen to drift by approximately one Coulomb oscillation per hour.",
        "positive": "Switching and Rectification of a Single Light-sensitive Diarylethene\n  Molecule Sandwiched between Graphene Nanoribbons: The 'open' and 'closed' isomers of the diarylethene molecule that can be\nconverted between each other upon photo-excitation are found to have\ndrastically different current-voltage characteristics when sandwiched between\ntwo graphene nanoribbons (GNRs). More importantly, when one GNR is metallic and\nanother one is semiconducting, strong rectification behavior of the 'closed'\ndiarylethene isomer with the rectification ratio >10^3 is observed. The\nsurprisingly high rectification ratio originates from the band gap of GNR and\nthe bias-dependent variation of the lowest unoccupied molecular orbital (LUMO)\nof the diarylethene molecule, the combination of which completely shuts off the\ncurrent at positive biases. Results presented in this paper may form the basis\nfor a new class of molecular electronic devices."
    },
    {
        "anchor": "Observation of an unexpected negative magnetoresistance in magnetic Weyl\n  semimetal Co$_3$Sn$_2$S$_2$: Time-reversal symmetry breaking allows for a rich set of magneto-transport\nproperties related to electronic topology. Focusing on the magnetic Weyl\nsemimetal Co$_3$Sn$_2$S$_2$, we prepared micro-ribbons and investigated their\ntransverse and longitudinal transport properties from 100 K to 180 K in\nmagnetic fields $\\mu_0 H$ up to 2T. We establish the presence of a\nmagnetoresistance (MR) up to 1 % with a strong anisotropy depending the\nprojection of $H$ on the easy-axis magnetization, which exceeds all other\nmagnetoresistive effects. Based on detailed phenomenological modeling, we\nattribute the observed results with unexpected form of anisotropy to magnon MR\nresulting from magnon-electron coupling. Moreover, a similar angular dependence\nis also found in the transverse resistivity which we show to originate from the\ncombination of ordinary Hall and anomalous Hall effects. Thus the interplay of\nmagnetic and topological properties governs the magnetotransport features of\nthis magnetic Weyl system.",
        "positive": "Effect of spin relaxations on the spin mixing conductances for a bilayer\n  structure: The spin current can result in a spin-transfer torque in the\nnormal-metal(NM)|ferromagnetic-insulator(FMI) or\nnormal-metal(NM)|ferromagnetic-metal(FMM) bilayer. In the earlier study on this\nissue, the spin relaxations were ignored or introduced phenomenologically. In\nthis paper, considering the FMM or FMI with spin relaxations described by a\nnon-Hermitian Hamiltonian, we derive an effective spin-transfer torque and an\neffective spin mixing conductance in the non-Hermitian bilayer. The dependence\nof the effective spin mixing conductance on the system parameters (such as\ninsulating gap, \\textit{s-d} coupling, and layer thickness) as well as the\nrelations between the real part and the imaginary part of the effective spin\nmixing conductance are given and discussed. We find that the effective spin\nmixing conductance can be enhanced in the non-Hermitian system. This provides\nus with the possibility to enhance the spin mixing conductance."
    },
    {
        "anchor": "Enhancement of electron spin lifetime in GaAs crystals: the benefits of\n  dichotomous noise: The electron spin relaxation process in n-type GaAs crystals driven by a\nfluctuating electric field is investigated. Two different sources of\nfluctuations are considered: (i) a symmetric dichotomous noise and (ii) a\nGaussian correlated noise. Monte Carlo numerical simulations show, in both\ncases, an enhancement of the spin relaxation time by increasing the amplitude\nof the external noise. Moreover, we find that the electron spin lifetime versus\nthe noise correlation time: (i) increases up to a plateau in the case of\ndichotomous random fluctuations, and (ii) shows a nonmonotonic behaviour with a\nmaximum in the case of bulks subjected to a Gaussian correlated noise.",
        "positive": "Optical sensing of fractional quantum Hall effect in graphene: Graphene and its van der Waals (vdW) heterostructures provide a unique and\nversatile playground for explorations of strongly correlated electronic phases,\nranging from unconventional fractional quantum Hall (FQH) states in a monolayer\nsystem to a plethora of superconducting and insulating states in twisted\nbilayers. However, the access to those fascinating phases has been thus far\nentirely restricted to transport techniques, due to the lack of a robust energy\nbandgap that makes graphene hard to access optically. Here we demonstrate an\nall-optical, non-invasive spectroscopic tool for probing electronic\ncorrelations in graphene using excited Rydberg excitons in an adjacent\ntransition metal dichalcogenide monolayer. Due to their large Bohr radii,\nRydberg states are highly susceptible to the compressibility of graphene\nelectrons, allowing us to detect the formation of odd-denominator FQH states at\nhigh magnetic fields. Owing to its sub-micron spatial resolution, the technique\nwe demonstrate circumvents spatial inhomogeneities in vdW structures, and paves\nthe way for optical studies of correlated states in twisted bilayer graphene\nand other optically inactive atomically-thin materials."
    },
    {
        "anchor": "Spin-based single-photon transistor, dynamic random access memory,\n  diodes and routers in semiconductors: The realization of quantum computers and quantum Internet requires not only\nquantum gates and quantum memories, but also transistors at single-photon\nlevels to control the flow of information encoded on single photons.\nSingle-photon transistor (SPT) is an optical transistor in the quantum limit,\nwhich uses a single photon to open or block a photonic channel. In sharp\ncontrast to all previous SPT proposals which are based on single-photon\nnonlinearities, here I present a novel design for a high-gain and high-speed\n(up to THz) SPT based on a linear optical effect - giant circular birefringence\n(GCB) induced by a single spin in a double-sided optical microcavity. A gate\nphoton sets the spin state via projective measurement and controls the light\npropagation in the optical channel. This spin-cavity transistor can be directly\nconfigured as diodes, routers, DRAM units, switches, modulators, etc. Due to\nthe duality as quantum gate and transistor, the spin-cavity unit provides a\nsolid-state platform ideal for future Internet - a mixture of all-optical\nInternet with quantum Internet.",
        "positive": "Thermally Assisted Current-Driven Skyrmion Motion: We study the behavior of skyrmions in thin films under the action of\nstochastic torques arising from thermal fluctuations. We find that the Brownian\nmotion of skyrmions is described by a stochastic Thiele's equation and its\ncorresponding Fokker-Planck equation. The resulting Fokker-Planck equation is\nrecognized as the one for a high-friction Brownian particle which has been\nstudied extensively in different physical contexts. It is shown that thermal\nfluctuations favor the skyrmion motion allowing a finite mobility even in\npresence of pinning traps. We calculate explicitly the mobility tensor of\nskyrmions in linear response to an electric current finding that it increases\nwith temperature."
    },
    {
        "anchor": "Unusual scenario of the temperature evolution of magnetic state in novel\n  carbon-based nanomaterials: Two porous carbon-based samples doped with Au and Co are investigated. The\nneutron diffraction study reveals an amorphous structure of both samples. The\nCo-doped sample exhibits a long-range ferromagnetic (FM) ordering at 2.6 K. The\nNMR investigations demonstrate, that the samples are obtained with a partial\ncarbonization of initial aromatic compounds and do not reach a state of glassy\ncarbon. The magnetization, longitudinal nonlinear response to a weak ac field\nand electron magnetic resonance data give evidences for presence of FM clusters\nin the samples well above 300 K. A short-range character of the FM ordering in\nthe Au-doped sample transforms below T$_C \\approx$ 210 K into another\ninhomogeneous FM state. Besides the FM clusters, this state contains a\nsubsystem with a long-range FM ordering (matrix) formed by paramagnetic\ncenters, existing outside the clusters. The nonlinear response data suggest a\npercolative character of the long-range FM matrix, which is connected probably\nwith a porous sample structure. The magnetization data give evidence for the\nformation of an inhomogeneous state in the Co-doped sample, similar to that in\nthe Au-doped one. However, this state is formed at higher temperatures, lying\nwell above 350 K, and exhibits a more homogeneous arrangement of the FM\nnanoparticles and the FM matrix. Temperature dependence of the magnetization in\nthe Au-doped sample is attributable to changes of the domain formation regime\nin the FM matrix on cooling, connected with the inhomogeneous character of its\nFM state. Such peculiarity is absent in the Co-doped sample below 350 K, which\nis in agreement with formation of the FM state in this sample at much higher\ntemperatures. Further cooling below T ~ 3(10) K leads to a steep increase of\nthe magnetization in both samples. This is attributable to the domain\nrearrangement in the inhomogeneous FM state at low temperatures.",
        "positive": "Electromagnetic Response of Three-dimensional Topological Crystalline\n  Insulators: Topological crystalline insulators (TCI) are a new class of materials which\nhave metallic surface states on select surfaces due to point group crystalline\nsymmetries. In this letter, we consider a model for a three-dimensional (3D)\ntopological crystalline insulator with Dirac nodes occurring on a surface that\nare protected by the mirror and time reversal symmetry. We demonstrate that the\nelectromagnetic response for such a system is characterized by a $1$-form\n$b_{\\mu}$. $b_{\\mu}$ can be inferred from the locations of the surface Dirac\nnodes in energy-momentum space and couples to the surface Dirac nodes like a\nvalley gauge field. From both the effective action and analytical band\nstructure calculations, we show that the vortex core of $\\vec b$ or a domain\nwall of a component of $\\vec b$ can trap surface charges."
    },
    {
        "anchor": "Nonadiabatic Landau Zener tunneling in Fe_8 molecular nanomagnets: The Landau Zener method allows to measure very small tunnel splittings \\Delta\nin molecular clusters Fe_8. The observed oscillations of \\Delta as a function\nof the magnetic field applied along the hard anisotropy axis are explained in\nterms of topological quantum interference of two tunnel paths of opposite\nwindings. Studies of the temperature dependence of the Landau Zener transition\nrate P gives access to the topological quantum interference between exited spin\nlevels. The influence of nuclear spins is demonstrated by comparing P of the\nstandard Fe_8 sample with two isotopically substituted samples. The need of a\ngeneralized Landau Zener transition rate theory is shown.",
        "positive": "Transport and field emission properties of buckypapers obtained from\n  aligned carbon nanotubes: We produce 120 um thick buckypapers from aligned carbon nanotubes. Transport\ncharacteristics evidence ohmic behavior in a wide temperature range, non\nlinearity appearing in the current-voltage curves only close to 4.2 K. The\ntemperature dependence of the conductance shows that transport is mostly due to\nthermal fluctuation induced tunneling, although to explain the whole\ntemperature range from 4.2 K to 430 K a further linear contribution is\nnecessary. The field emission properties are measured by means of a\nnanocontrolled metallic tip acting as collector electrode to access local\ninformation about buckypaper properties from areas as small as 1 um2. Emitted\ncurrent up to 10-5A and turn-on field of about 140V/um are recorded. Long\noperation, stability and robustness of emitters have been probed by field\nemission intensity monitoring for more than 12 hours at pressure of 10-6 mbar.\nFinally, no tuning of the emitted current was observed for in plane applied\ncurrents in the buckypaper."
    },
    {
        "anchor": "Lateral plasmonic crystals: Tunability, dark modes, and weak-to-strong\n  coupling transition: We study transmission of the terahertz radiation through a two-dimensional\nelectron gas with a concentration controlled by grating gate electrodes.\nVoltage applied to these electrodes creates a lateral plasmonic crystal with a\ngate-tunable band structure. We find that only a part of plasmonic modes of\nsuch a crystal is seen in the transmission spectrum for the case of homogeneous\nexcitation (so-called bright modes), while there also exist dark modes which\nshow up only in a case of inhomogeneous excitation. We develop a theory that\ndescribes both weak- to strong- coupling transition in the crystal with\nincreasing depth of the density modulation and a transition from resonant to\nsuper-resonant regime with increasing quality factor of the structure. We\ndiscuss very recent experiment, where transmission of the terahertz radiation\nthrough GaN/AlGaN based grating gate periodic structures was studied. We argue\nthat this experiment represents an evidence of formation of the lateral\nplasmonic crystal with the band structure fully controlled by the gate\nelectrodes and magnetic field, in a full agreement with developed theory.",
        "positive": "Towards a realistic transport modeling in a superconducting nanowire\n  with Majorana fermions: Motivated by recent experiments searching for Majorana fermions (MFs) in\nhybrid semiconducting-superconducting nanostructures, we consider a realistic\ntight-binding model and analyze its transport behavior numerically. In\nparticular, we take into account the presence of a superconducting contact,\nused in real experiments to extract the current, which is usually not included\nin theoretical calculations. We show that important features emerge that are\nabsent in simpler models, such as the shift in energy of the proximity gap\nsignal, and the enhanced visibility of the topological gap for increased\nspin-orbit interaction. We find oscillations of the zero bias peak as a\nfunction of the magnetic field and study them analytically. We argue that many\nof the experimentally observed features hint at an actual spin-orbit\ninteraction larger than the one typically assumed. However, even taking into\naccount all the known ingredients of the experiments and exploring many\nparameter regimes for MFs, we are not able to reach full agreement with the\nreported data. Thus, a different physical origin for the observed zero-bias\npeak cannot be excluded."
    },
    {
        "anchor": "The electronic properties of bilayer graphene: We review the electronic properties of bilayer graphene, beginning with a\ndescription of the tight-binding model of bilayer graphene and the derivation\nof the effective Hamiltonian describing massive chiral quasiparticles in two\nparabolic bands at low energy. We take into account five tight-binding\nparameters of the Slonczewski-Weiss-McClure model of bulk graphite plus intra-\nand interlayer asymmetry between atomic sites which induce band gaps in the\nlow-energy spectrum. The Hartree model of screening and band-gap opening due to\ninterlayer asymmetry in the presence of external gates is presented. The\ntight-binding model is used to describe optical and transport properties\nincluding the integer quantum Hall effect, and we also discuss orbital\nmagnetism, phonons and the influence of strain on electronic properties. We\nconclude with an overview of electronic interaction effects.",
        "positive": "Long-range exchange interaction between spin qubits mediated by a\n  superconducting link at finite magnetic field: Solid state spin qubits are promising candidates for the realization of a\nquantum computer due to their long coherence times and easy electrical\nmanipulation. However, spin-spin interactions, which are needed for entangling\ngates, have only limited range as they generally rely on tunneling between\nneighboring quantum dots. This severely constrains scalability. Proposals to\nextend the interaction range generally focus on coherent electron transport\nbetween dots or on extending the coupling range. Here, we study a setup where\nsuch an extension is obtained by using a superconductor as a quantum mediator.\nBecause of its gap, the superconductor effectively acts as a long tunnel\nbarrier. We analyze the impact of spin-orbit (SO) coupling, external magnetic\nfields, and the geometry of the superconductor. We show that while spin\nnon-conserving tunneling between the dots and the superconductor due to SO\ncoupling does not affect the exchange interaction, strong SO scattering in the\nsuperconducting bulk is detrimental. Moreover, we find that the addition of an\nexternal magnetic field decreases the strength of the exchange interaction.\nFortunately, the geometry of the superconducting link offers a lot of room to\noptimize the interaction range, with gains of over an order of magnitude from a\n2D film to a quasi-1D strip. We estimate that for superconductors with weak SO\ncoupling (\\textit{e.g.}, aluminum) exchange rates of up to 100\\,MHz over a\nmicron-scale range can be achieved with this setup in the presence of magnetic\nfields of the order of 100\\,mT."
    },
    {
        "anchor": "Influence of spin-flip on the performance of the spin-diode: We study spin-dependent transport through a spin diode in the presence of\nspin-flip by means of reduced density matrix approach. The current polarization\nand the spin accumulation are computed and influence of spin-flip on the\ncurrent polarization is also analyzed. Analytical relations for the current\npolarization and the spin accumulation are obtained as a function of\npolarization of ferromagnetic lead and the spin-flip rate. It is observed that\nthe current polarization becomes zero under fast spin-flip and the spin\naccumulation decreases up to %85 when the time of spin-flip is equal to the\ntunneling time. It is also observed that the current polarization increases\nlinearly when the dot is singly occupied, whereas its behavior is more\ncomplicated when the dot is doubly occupied.",
        "positive": "General planar transverse domain walls realized by optimized transverse\n  magnetic field pulses in magnetic biaxial nanowires: We report the realization of a planar transverse domain wall (TDW) with\narbitrary tilting angle in a magnetic biaxial nanowire under a transverse\nmagnetic field (TMF) pulse with fixed strength and optimized orientation\nprofile. We smooth any twisting in azimuthal angle plane of a TDW and thus\ncompletely decouple the polar and azimuthal degrees of freedom. The analytical\ndifferential equation that describes the polar angle distribution is then\nderived and the resulting solution is not a Walker-ansatz form. With this\noptimized TMF pulse comoving, the field-driven dynamics of the planar TDW is\ninvestigated. It turns out the comoving TMF pulse increases the wall velocity\nunder the same axial driving field. These results will help to design a series\nof modern logic and memory nanodevices based on general planar TDWs."
    },
    {
        "anchor": "Geometrical effects on spin injection: 3D spin drift diffusion model: We discuss a three-dimensional (3D) spin drift diffusion (SDD) model to\ninject spin from a ferromagnet (FM) to a normal metal (N) or semiconductor\n(SC). Using this model we investigate the problem of spin injection into\nisotropic materials like GaAs and study the effect of FM contact area and SC\nthickness on spin injection. We find that in order to achieve detectable spin\ninjection a small contact area or thick SC samples are essential for direct\ncontact spin injection devices. We investigate the use of thin metal films (Cu)\nproposed by S.B. Kumar et al. and show that they are an excellent substitute\nfor tunnelling barriers (TB) in the regime of small contact area. Since most\ntunnelling barriers are prone to pinhole defects, we study the effect of\npinholes in AlO tunnelling barriers and show that the reduction in the\nspin-injection ratio ($\\gamma$) is solely due to the effective area of the\npinholes and there is no correlation between the number of pinholes and the\nspin injection ratio.",
        "positive": "Wavelength Dependence of Picosecond Laser-Induced Periodic Surface\n  Structures on Copper: The physical mechanisms of the laser-induced periodic surface structures\n(LIPSS) formation are studied in this paper for single-pulse irradiation\nregimes. The change in the LIPSS period with wavelength of incident laser\nradiation is investigated experimentally, using a picosecond laser system,\nwhich provides 7-ps pulses in near-IR, visible, and UV spectral ranges. The\nexperimental results are compared with predictions made under the assumption\nthat the surface-scattered waves are involved in the LIPSS formation.\nConsiderable disagreement suggests that hydrodynamic mechanisms can be\nresponsible for the observed pattern periodicity."
    },
    {
        "anchor": "Superconductivity in hyperdoped Ge by molecular beam epitaxy: Superconducting germanium films are an intriguing material for possible\napplications in fields such as cryogenic electronics and quantum bits.\nRecently, there has been great deal of progress in hyperdoping of Ga doped Ge\nusing ion implantation. The thin film growths would be advantageous allowing\nhomoepitaxy of doped and undoped Ge films opening possibilities for vertical\nJosephson junctions. Here, we present our studies on the growth of one layer of\nhyperdoped superconducting germanium thin film via molecular beam epitaxy. We\nobserve a fragile superconducting phase which is extremely sensitive to\nprocessing conditions and can easily phase-segregate, forming a percolated\nnetwork of pure gallium metal. By suppressing phase segregation through\ntemperature control we find a superconducting phase that is unique and appears\ncoherent to the underlying Ge substrate.",
        "positive": "Finite electron crystallites in strong magnetic fields: Precursors of a\n  supersolid?: We show that a supersolid phase, exhibiting simultaneously solid and\nsuperfluid behavior, properly describes the finite electron crystallites that\nform in two-dimensional quantum dots under high magnetic fields. These\ncrystallites rotate already in their ground state and exhibit a nonclassical\nrotational inertia. They are precursors to a supersolid crystal in the lowest\nLandau level. We use exact numerical diagonalization, calculations employing\nanalytic many-body wave functions, and a newly derived analytic expression for\nthe total energies that permits calculations for arbitrary number of electrons."
    },
    {
        "anchor": "Moderate bandgap and high carrier mobility simultaneously realized in\n  bilayer silicene by oxidation: Semiconductors simultaneously possessing high carrier mobility, moderate\nbandgap, and ambient environment stability are so important for the modern\nindustry, and Si-based semiconducting materials can match well with the\nprevious silicon based electronic components. Thus, searching for such Si-based\nsemiconductors has been one hot project due to the lack of them nowadays. Here,\nwith the help of density functional theory, we found that the oxidized bilayer\nsilicene exhibits high carrier mobility with a moderate direct bandgap of 1.02\neV. The high carrier mobility is caused by the remaining of big pi bond, and\nthe moderate bandgap is opened by the saturation of dangling Si 3p bonds.\nOriginated from the formation of strong Si-O and Si-Si bonds, the sample\nexhibits strong thermodynamic and dynamical stabilities. Our work indicates\nthat the oxidized bilayer silicene has many potential applications in modern\nelectronic fields.",
        "positive": "Coherence recovery mechanisms in quantum Hall edge states: The work is motivated by the puzzling results of the recent experiment [S.\nTewari et al., Phys. Rev. B 93, 035420 (2016)], where a robust coherence\nrecovery from a certain energy was detected for an electron injected into the\nquantum Hall edge at the filling factor 2. After passing through a quantum dot\nthe electron then tunnels into the edge with a subsequent propagation towards a\nsymmetric Mach-Zender interferometer, after which the visibility of\nAharonov-Bohm (AB) oscillations is measured. According to conventional\nunderstanding its decay with the increasing energy of the injected electron was\nexpected, which was confirmed theoretically in the bosonization framework. Here\nwe analyze why such a model fails to account for the coherence recovery and\nshow that the reason is essentially the destructive interference of the two\nquasiparticles (charge and neutral modes) forming at the edge out of the\nincoming electron. This statement is robust with respect to the strength of\nCoulomb interaction. We firstly exploit the idea of introducing an imbalance\nbetween the quasiparticles, by creating different conditions of propagation for\nthem. It can be done by taking into account either dispersion or dissipation,\nwhich indeed results in the partial coherence recovery. The idea of imbalance\ncan also be realized by applying a periodic potential to the arms of\ninterferometer. We discuss such an experiment, which might also shed light on\nthe internal coherence of the two edge excitations. Another scenario relies on\nthe lowering of the energy density of the electron wave packet by the time it\narrives at the interferometer in presence of dissipation or dispersion. This\nenergy density is defined by a certain parameter, which is completely\nindependent of the injected energy, which naturally explains the emergence of a\nthreshold energy in the experiment."
    },
    {
        "anchor": "Suppression of magnetic ordering in XXZ-type antiferromagnetic monolayer\n  NiPS3: How a certain ground state of complex physical systems emerges, especially in\ntwo-dimensional materials, is a fundamental question in condensed-matter\nphysics. A particularly interesting case is systems belonging to the class of\nXY Hamiltonian where the magnetic order parameter of conventional nature is\nunstable in two-dimensional materials leading to a\nBerezinskii-Kosterlitz-Thouless transition. Here, we report how the XXZ-type\nantiferromagnetic order of a magnetic van der Waals material, NiPS3, behaves\nupon reducing the thickness and ultimately becomes unstable in the monolayer\nlimit. Our experimental data are consistent with the findings based on\nrenormalization group theory that at low temperatures a two-dimensional XXZ\nsystem behaves like a two-dimensional XY one, which cannot have a long-range\norder at finite temperatures. This work provides experimental examination of\nthe XY magnetism in the atomically thin limit and opens new opportunities of\nexploiting these fundamental theorems of magnetism using magnetic van der Waals\nmaterials.",
        "positive": "Two-dimensional electronic spectroscopy from first principles: The recent development of multidimensional ultrafast spectroscopy techniques\ncalls for the introduction of computational schemes that allow for the\nsimulation of such experiments and the interpretation of the corresponding\nresults from a microscopic point of view. In this work, we present a general\nand efficient first-principles scheme to compute two-dimensional electronic\nspectroscopy maps based on real-time time-dependent density-functional theory.\nThe interface of this approach with the Ehrenfest scheme for molecular dynamics\nenables the inclusion of vibronic effects in the calculations based on a\nclassical treatment of the nuclei. The computational complexity of the\nsimulations is reduced by the application of numerical advances such as\nbranching techniques, undersampling, and a novel reduced phase cycling scheme,\napplicable for systems with inversion symmetry. We demonstrate the\neffectiveness of this method by applying it to prototypical molecules such as\nbenzene, pyridine, and pyrene. We discuss the role of the approximations that\ninevitably enter the adopted theoretical framework and set the stage for\nfurther extensions of the proposed method to more realistic systems."
    },
    {
        "anchor": "A new route towards uniformly functionalized single-layer graphene: It is shown, by DFT calculations, that the uniform functionalization of upper\nlayer of graphite by hydrogen or fluorine does not change essentially its\nbonding energy with the underlying layers, whereas the functionalization by\nphenyl groups decreases the bonding energy by a factor of approximately ten.\nThis means that the functionalized monolayer in the latter case can be easily\nseparated by mild sonication. According to our computational results, such\nlayers can be cleaned up to pure graphene, as well as functionalized further up\nto 25% coverage, without essential difficulties. The energy gap within the\ninterval from 0.5 to 3 eV can be obtained by such one-side funtionalization\nusing different chemical species.",
        "positive": "Quantum beats in the polarization of the spin-dependent photon echo from\n  donor-bound excitons in CdTe/(Cd,Mg)Te quantum wells: We study the quantum beats in the polarization of the photon echo from\ndonor-bound exciton ensembles in semiconductor quantum wells. To induce these\nquantum beats, a sequence composed of a circularly polarized and a linearly\npolarized picosecond laser pulse in combination with an external transverse\nmagnetic field is used. This results in an oscillatory behavior of the photon\necho amplitude, detected in the $\\sigma^+$ and $\\sigma^-$ circular\npolarizations, occurring with opposite phases relative to each other. The\nbeating frequency is the sum of the Larmor frequencies of the resident electron\nand the heavy hole when the second pulse is polarized along the magnetic field.\nThe beating frequency is, on the other hand, the difference of these Larmor\nfrequencies when the second pulse is polarized orthogonal to the magnetic\nfield. The measurement of both beating frequencies serves as a method to\ndetermine precisely the in-plane hole $g$ factor, including its sign. We apply\nthis technique to observe the quantum beats in the polarization of the photon\necho from the donor-bound excitons in a 20-nm-thick\nCdTe/Cd$_{0.76}$Mg$_{0.24}$Te quantum well. From these quantum beats we obtain\nthe in-plane heavy hole $g$ factor $g_h=-0.143\\pm0.005$."
    },
    {
        "anchor": "Theory of spin inelastic tunneling spectroscopy for\n  superconductor-superconductor and superconductor-metal junctions: We address the tunneling conductance and spin inelastic tunneling\nspectroscopy of localized paramagnetic moments in a superconducting\nenvironment, pertaining to recent measurements on\nFe-octaethylporphyrin-chloride using superconducting scanning tunneling\nmicroscopy. We demonstrate that the Cooper pair correlations in the tip and\nsubstrate generate a finite uniaxial anisotropy field acting on the local spin\nmoment, and we argue that this field may be a source for the observed changes\nin the conductance spectrum for decreasing distance between the scanning\ntunneling tip and the local magnetic moment. We make a side-by-side comparison\nbetween the superconductor-superconductor junction and\nnormal-metal--superconductor junction, and find qualitative agreement between\nthe two setups while quantitative differences become explicit.\n  When simulating the effects of electron pumping, we obtain additional peaks\nin the conductance spectrum that can be attributed to excitations between\nhigher-energy spin states. The transverse anisotropy field couples basis states\nof the local spin which opens for transitions between spin states that are\notherwise forbidden by conservation of angular momentum. Finally, we explore\nthe influences of temperature, which tend to enable in-gap transitions, and an\nexternal magnetic field, which enables deeper studies of the spin excitation\nspectrum. We especially notice the appearance of a low and high excitation peak\non each side of the main coherence peak as an imprint of transitions between\nthe Zeeman split ground states.",
        "positive": "Energy-efficient domain wall motion governed by the interplay of\n  helicity-dependent optical effect and spin-orbit torque: Spin-orbit torque provides a powerful means of manipulating domain walls\nalong magnetic wires. However, the current density required for domain wall\nmotion is still too high to realize low power devices. Here we experimentally\ndemonstrate helicity-dependent domain wall motion by combining synchronized\nfemtosecond laser pulses and short current pulses in Co/Ni/Co ultra-thin film\nwires with perpendicular magnetization. Domain wall can remain pinned under one\nlaser circular helicity while depinned by the opposite circular helicity.\nThanks to the all-optical helicity-dependent effect, the threshold current\ndensity due to spin-orbit torque can be reduced by more than 50%. Based on this\njoint effect combining spin-orbit torque and helicity-dependent laser pulses,\nan optoelectronic logic-in-memory device has been experimentally demonstrated.\nThis work enables a new class of low power spintronic-photonic devices beyond\nthe conventional approach of all-optical switching or all-current switching for\ndata storage."
    },
    {
        "anchor": "Unconventional p-wave magnets: The electronic structure of atoms is organized into even and odd-parity-wave\ns, p, d, ... orbitals. An analogous classification of condensed matter phases\nemerged with the discovery of conventional s-wave superconductivity in mercury,\nfollowed by the discoveries of unconventional p-wave superfluidity in $^{3}$He\nand unconventional d-wave superconductivity in cuprates. To date, the known\ncounterparts in magnetism have been the conventional ferromagnets with s-wave\nspin polarization in the electronic structure, and the recently discovered\naltermagnets[1-3] with unconventional d-wave and higher even-parity wave spin\npolarization[1,2,4-7]. Here we identify the long-sought magnetic counterpart of\nunconventional p-wave superfluidity[8,9] -- the unconventional magnet with\np-wave spin polarization[10,11]. We show that that collinear p-wave\nspin-polarization arises in a coplanar spin-symmetry subset of a class of\nnoncentrosymmetric and noncolinear magnetic crystals with combined\ntime-reversal and lattice translation symmetry. Contrary to common\nassumptions[12-15], we show that noncollinear magnets from this class\nuniversally exhibit nonrelativistic spin splittings and that these odd-parity\nwave spin splittings preserve time-reversal symmetry of the band structure. We\npredict large spin splitings reaching 500 meV by first-principles calculations\nand we identify 60 realistic material candidates. Inspired by the rich and\nanisotropic properties of superfluid $^{3}$He[8,9] our result opens up a wide\nrange of possibilities to investigate unconventional p-wave order parameters in\ncrystals and their exploitation in spintronics and topological physics[16-21].",
        "positive": "State Tomography of a Chain of Qubits Embedded in a Spin Field-Effect\n  Transistor via Repeated Spin-Blockade Measurements on the Edge Qubit: As a possible physical realization of a quantum information processor, a\nsystem with stacked self-assembled InAs quantum dots buried in GaAs in adjacent\nto the channel of a spin field-effect transistor has been proposed. In this\nsystem, only one of the stacked qubits, i.e. the edge qubit (the qubit closest\nto the channel), is measurable via \"spin-blockade measurement.\" It is shown\nthat the state tomography of the whole chain of the qubits is still possible\neven under such a restricted accessibility. The idea is to make use of the\nentangling dynamics of the qubits. A recipe for the two-qubit system is\nexplicitly constructed and the effect of an imperfect fidelity of the\nmeasurement is clarified. A general scheme for multiple qubits based on\nrepeated measurements is also presented."
    },
    {
        "anchor": "Josephson junction on one edge of a two dimensional topological\n  insulator affected by magnetic impurity: Current-phase relation in a Josephson junction formed by putting two s-wave\nsuperconductors on the same edge of a two dimensional topological insulator is\ninvestigated. We consider the case that the junction length is finite and\nmagnetic impurity exists. The similarity and difference with conventional\nJosephson junction is discussed. The current is calculated in the semiconductor\npicture. Both the $2\\pi$- and $4\\pi$-period current-phase relations\n($I_{2\\pi}(\\phi), I_{4\\pi}(\\phi)$) are studied. There is a sharp jump at\n$\\phi=\\pi$ and $\\phi=2\\pi$ for $I_{2\\pi}$ and $I_{4\\pi}$ respectively in the\nclean junction. For $I_{2\\pi}$, the sharp jump is robust against impurity\nstrength and distribution. However for $I_{4\\pi}$, the impurity makes the jump\nat $\\phi=2\\pi$ smooth. The critical (maximum) current of $I_{2\\pi}$ is given\nand we find it will be increased by asymmetrical distribution of impurity.",
        "positive": "Tunneling Spectra of Individual Magnetic Endofullerene Molecules: The manipulation of single magnetic molecules may enable new strategies for\nhigh-density information storage and quantum-state control. However, progress\nin these areas depends on developing techniques for addressing individual\nmolecules and controlling their spin. Here we report success in making\nelectrical contact to individual magnetic N@C60 molecules and measuring spin\nexcitations in their electron tunneling spectra. We verify that the molecules\nremain magnetic by observing a transition as a function of magnetic field which\nchanges the spin quantum number and also the existence of nonequilibrium\ntunneling originating from low-energy excited states. From the tunneling\nspectra, we identify the charge and spin states of the molecule. The measured\nspectra can be reproduced theoretically by accounting for the exchange\ninteraction between the nitrogen spin and electron(s) on the C60 cage."
    },
    {
        "anchor": "Magnonic Band Structure Established by Chiral Spin-Density Waves in Thin\n  Film Ferromagnets: Recent theoretical studies have demonstrated the possibility to excite and\nsustain noncollinear magnetization states in ferromagnetic nanowires. The\nresulting state is referred to as a spin-density wave (SDW). SDWs can be\ninterpreted as hydrodynamic states with a constant fluid density and fluid\nvelocity in systems with easy-plane anisotropy. Here, we consider the effect of\nthe nonlocal dipole field arising from the finite thickness of magnetic thin\nfilms on the spatial profile of the SDW and on the associated magnon\ndispersion. Utilizing a hydrodynamic formulation of the Larmor torque equation,\nit is found that the nonlocal dipole field modulates the fluid velocity. Such a\nmodulation induces a magnonic band structure unlike the typical dispersion\nrelation for magnons on uniform magnetization. The analytical results are\nvalidated by micromagnetic simulations. Band gaps on the order of GHz are\nnumerically observed to depend on the SDW fluid velocity and film thickness for\nrealistic material parameters. The presented results suggest that SDWs can find\napplications as reconfigurable magnonic crystals.",
        "positive": "Macroscopic quantum tunneling in PdO nanoparticles: We studied the physical behavior of PdO nanoparticles at low temperatures,\nwhich presents an unusual behavior clearly related to macroscopic quantum\ntunneling. The samples show a tetragonal single phase with P42/mmc space group.\nMost importantly, the particle size was estimated at about 5.07 nm. Appropriate\ntechniques were used to determine the characteristic of these nanoparticles.\nThe most important aspect of this study is the magnetic characterization\nperformed at low temperatures. It shows a peak at 50 K in zero field cooling\nmode (ZFC) that corresponds to the Blocking temperature (T$_{B}$). These\nmeasurements in ZFC and field cooling (FC) indicates that the peak behavior is\ndue to different relaxation times of the asymmetrical barriers when the\nelectron changes from a metastable state to another. Below T$_{B}$ in FC mode,\nthe magnetization decreases with temperature until 36 K; this temperature is\nthe crossover temperature (T$_{Cr}$) related to the anisotropy of the barriers,\nindicative of macroscopic quantum tunneling."
    },
    {
        "anchor": "Real-space topological localizer index to fully characterize the\n  dislocation skin effect: The dislocation skin effect exhibits the capacity of topological defects to\ntrap an extensive number of modes in two-dimensional non-Hermitian systems.\nSimilar to the corresponding skin effects caused by system boundaries, this\nphenomenon also originates from nontrivial topology. However, finding the\nrelationship between the dislocation skin effect and nonzero topological\ninvariants, especially in disordered systems, can be obscure and challenging.\nHere, we introduce a real-space topological invariant based on the spectral\nlocalizer to characterize the skin effect on two-dimensional lattices. We\ndemonstrate that this invariant consistently predicts the occurrence and\nlocation of both boundary and dislocation skin effects, offering a unified\napproach applicable to both ordered and disordered systems. Our work\ndemonstrates a general approach that can be utilized to diagnose the\ntopological nature of various types of skin effects, particularly in the\nabsence of translational symmetry when momentum-space descriptions are\ninapplicable.",
        "positive": "Noncommutative quantum mechanics and skew scattering in ferromagnetic\n  metals: The anomalous Hall effect in ferromagnetic metals is classified into two\nbased on the mechanism. The first one is the intrinsic Hall effect due to the\nBerry curvature in momentum space; this is a Hall effect that solely arises\nfrom the band structure of solids. On the other hand, another contribution to\nthe Hall effect, so-called extrinsic mechanism, comes from impurity scatterings\nsuch as skew scattering and side jump; for the extrinsic mechanism, the\nspin-orbit interaction of the impurity ions is often required. These two\nmechanisms are often discussed separately; the intrinsic Hall effect is\ndominant in the intermediate resistivity region while the latter, i.e., skew\nscattering, becomes important in the clean limit. In this work, it is shown\ntheoretically that the non-commutative nature of the real-space coordinates in\nthe presence of the Berry curvature causes the skew scattering by the\nnonmagnetic impurity without relativistic spin-orbit interactions, in sharp\ncontrast to the conventional cases."
    },
    {
        "anchor": "Plasmon-phonon coupling in graphene: Collective excitations of coupled electron-phonon systems are calculated for\nboth monolayer and bilayer graphene, taking into account the non-perturbative\nCoulomb coupling between electronic excitations in graphene and the substrate\nlongitudinal optical phonon modes. We find that the plasmon-phonon coupling in\nmonolayer graphene is strong at all densities, but in bilayer graphene the\ncoupling is significant only at high densities satisfying the resonant\ncondition $\\omega_{pl} \\approx \\omega_{ph}$. The difference arises from the\npeculiar screening properties associated with chirality of graphene.\nPlasmon-phonon coupling explains the measured quasi-linear plasmon dispersion\nin the long wavelength limit, thus resolving a puzzle in the experimental\nobservations.",
        "positive": "Ab-initio calculations for electronic and optical properties of Er$_{\\rm\n  W}$ defects in tungsten disulfide: Ab-initio calculations for the electronic and optical properties of\nsingle-layer (SL) tungsten disulfide (WS$_2$) in the presence of substitutional\nErbium defects (Er$_{\\rm W}$) are presented, where the W atom is replaced by an\nEr atom. Defects usually play an important role in tailoring electronic and\noptical properties of semiconductors. We show that neutral Er defects lead to\nlocalized defect states (LDS) in the band structure due to the f-orbital states\nof Er, which in turn give rise to sharp transitions in in-plane and\nout-of-plane optical absorption spectra, $\\alpha_{\\parallel}$ and\n$\\alpha_{\\perp}$. We identify the optical transitions at 3 $\\mu$m, 1.5 $\\mu$m,\n1.2 $\\mu$m, 920 nm, 780 nm, 660 nm, and 550 nm to originate from Er$_{\\rm W}$\ndefect states. In order to provide a clear description of the optical\nabsorption spectra, we use group theory to derive the optical selection rules\nbetween LDS for both $\\alpha_{\\parallel}$ and $\\alpha_{\\perp}$."
    },
    {
        "anchor": "Electron phase shift at the zero-bias anomaly of quantum point contacts: The Kondo effect is the many-body screening of a local spin by a cloud of\nelectrons at very low temperature. It has been proposed as an explanation of\nthe zero-bias anomaly in quantum point contacts where interactions drive a\nspontaneous charge localization. However, the Kondo origin of this anomaly\nremains under debate, and additional experimental evidence is necessary. Here\nwe report on the first phase-sensitive measurement of the zero-bias anomaly in\nquantum point contacts using a scanning gate microscope to create an electronic\ninterferometer. We observe an abrupt shift of the interference fringes by half\na period in the bias range of the zero-bias anomaly, a behavior which cannot be\nreproduced by single-particle models. We instead relate it to the phase shift\nexperienced by electrons scattering off a Kondo system. Our experiment\ntherefore provides new evidence of this many-body effect in quantum point\ncontacts.",
        "positive": "Quantum Hall Smectics, Sliding Symmetry and the Renormalization Group: In this paper we discuss the implication of the existence of a sliding\nsymmetry, equivalent to the absence of a shear modulus, on the low-energy\ntheory of the quantum hall smectic (QHS) state. We show, through\nrenormalization group calculations, that such a symmetry causes the naive\ncontinuum approximation in the direction perpendicular to the stripes to break\ndown through infrared divergent contributions originating from naively\nirrelevant operators. In particular, we show that the correct fixed point has\nthe form of an array of sliding Luttinger liquids which is free from\nsuperficially \"irrelevant operators\". Similar considerations apply to all\ntheories with sliding symmetries."
    },
    {
        "anchor": "Coupled-Mode Theory of Field Enhancement in Complex Metal Nanostructures: We describe a simple yet rigorous theoretical model capable of analytical\nestimation of plasmonic field enhancement in complex metal structures. We show\nthat one can treat the complex structures as coupled multi-pole modes with\nhighest enhancements obtained due to superposition of high order modes in small\nparticles. The model allows one to optimize the structures for the largest\npossible field enhancements, which depends on the quality factor Q of the metal\nand can be as high as Q^2 for two spherical particles. The \"hot spot\" can occur\neither in the nano-gaps between the particles or near the smaller particles. We\ntrace the optimum field enhancement mechanism to the fact that the extended\ndipole modes of larger particles act as the efficient antennas while the modes\nin the gaps or near the smaller particles act as the compact sub-wavelength\ncavities. We also show how easily our approach can be extended to incorporate\nlarge numbers of particles in intricate arrangements.",
        "positive": "Strain-induced modifications of transport in gated graphene nanoribbons: We investigate the effects of homogeneous and inhomogeneous deformations and\nedge disorder on the conductance of gated graphene nanoribbons. Under\nincreasing homogeneous strain the conductance of such devices initially\ndecreases before it acquires a resonance structure, and finally becomes\ncompletely suppressed at larger strain. Edge disorder induces mode mixing in\nthe contact regions, which can restore the conductance to its ballistic value.\nThe valley-antisymmetric pseudo-magnetic field induced by inhomogeneous\ndeformations leads to the formation of additional resonance states, which\neither originate from the coupling into Fabry-Perot states that extend through\nthe system, or from the formation of states that are localized near the\ncontacts, where the pseudo-magnetic field is largest. In particular, the n=0\npseudo-Landau level manifests itself via two groups of conductance resonances\nclose to the charge neutrality point."
    },
    {
        "anchor": "Structure of the nearly-degenerate manifold of lattice quasiholes on a\n  torus: We study the nearly-degenerate quasihole manifold of the bosonic\nHofstadter-Hubbard model on a torus, known to host the lattice analog of the\nLaughlin state at filling fraction $\\nu = 1/2$. Away from $\\nu = 1/2$ and in\nthe presence of both localized and delocalized quasiholes, the ratio between\nthe numerically calculated many-body Chern number for certain groups of states\nand the number of states in the relevant group turns out to be constant for\nthis manifold, which is also manifested in the density profile as the depleted\ncharge of localized quasiholes. Inspired by a zero-mode counting formula\nderivable from a generalized Pauli principle, we employ a combinatorial scheme\nto account for the splittings in the manifold, allowing us to interpret some\ngroups of states as the quasihole excitations corresponding to filling\nfractions lower than $\\nu = 1/2$. In this scheme, the many-body Chern number of\nsubgroups appears as a simple combinatorial factor.",
        "positive": "Current-induced dynamics of skyrmion tubes in synthetic\n  antiferromagnetic multilayers: Topological spin textures can be found in both two-dimensional and\nthree-dimensional nanostructures, which are of great importance to advanced\nspintronic applications. Here we report the current-induced skyrmion tube\ndynamics in three-dimensional synthetic antiferromagnetic (SyAF) bilayer and\nmultilayer nanostructures. It is found that the SyAF skyrmion tube made of\nthinner sublayer skyrmions is more stable during its motion, which ensures that\na higher speed of the skyrmion tube can be reached effectively at larger\ndriving current. In the SyAF multilayer with a given total thickness, the\ncurrent-induced deformation of the SyAF skyrmion tube decreases with an\nincreasing number of interfaces; namely, the rigidity of the SyAF skyrmion tube\nwith a given thickness increases with the number of ferromagnetic (FM) layers.\nFor the SyAF multilayer with an even number of FM layers, the skyrmion Hall\neffect can be eliminated when the thicknesses of all FM layers are identical.\nLarger damping parameter leads to smaller deformation and slower speed of the\nSyAF skyrmion tube. Larger fieldlike torque leads to larger deformation and a\nhigher speed of the SyAF skyrmion tube. Our results are useful for\nunderstanding the dynamic behaviors of three-dimensional topological spin\ntextures and may provide guidelines for building SyAF spintronic devices."
    },
    {
        "anchor": "A Cantilever Torque Magnetometry Method for the Measurement of Hall\n  Conductivity of Highly Resistive Samples: We present the first measurements of Hall conductivity utilizing a new torque\nmagnetometry method designed for insulators. A Corbino disk exhibits a magnetic\ndipole moment proportional to Hall conductivity when voltage is applied across\na test material. This magnetic dipole moment can be measured through torque\nmagnetometry. The symmetry of this contactless technique allows for the\nmeasurement of Hall conductivity in previously inaccessible materials. Finally,\na low-temperature noise bound, the lack of systematic errors on dummy devices,\nand a measurement of the Hall conductivity of sputtered indium tin oxide\ndemonstrate the efficacy of the technique.",
        "positive": "Nonadiabatic scattering of a quantum particle in an inhomogenous\n  magnetic field: We investigate the quantum effects, in particular the Landau-level\nquantization, in the scattering of a particle the nonadiabatic classical\ndynamics of which is governed by an adiabatic invariant. As a relevant example,\nwe study the scattering of a drifting particle on a magnetic barrier in the\nquantum limit where the cyclotron energy is much larger than a broadening of\nthe Landau levels induced by the nonadiabatic transitions. We find that,\ndespite the level quantization, the exponential suppression $\\exp(-2\\pi\nd/\\delta)$ (barrier width $d$, orbital shift per cyclotron revolution $\\delta$)\nof the root-mean-square transverse displacement experienced by the particle\nafter the scattering is the same in the quantum and the classical regime."
    },
    {
        "anchor": "Surface states influence in the conductance spectra of Co adsorbed on\n  Cu(111): We calculate the conductance spectra of a Co atom adsorbed on Cu(111),\nconsidering the Co $3d$ orbitals within a correlated multiple configurations\nmodel interacting through the substrate band with the Co $4s$ orbital, which is\ntreated in a mean-field like approximation. By symmetry, only the $d_{z^2}$\norbital couples with the $s$ orbital through the Cu bands, and the interference\nbetween both conduction channels introduces a zero-bias anomaly in the\nconductance spectra. We find that, while the Kondo resonance is mainly\ndetermined by the interaction of the Co $d$ orbitals with the bulk states of\nthe Cu(111) surface, a proper description of the contribution given by the\ncoupling with the localized surface states to the Anderson widths is crucial to\ndescribe the interference line shape. We find that the coupling of the Co $4s$\norbital with the Shockley surface states is responsible of two main features\nobserved in the measured conductance spectra, the dip shape around the Fermi\nenergy and the resonance structure at the surface state low band edge.",
        "positive": "Plasmons in graphene on uniaxial substrates: Placing graphene on uniaxial substrates may have interesting application\npotential for graphene-based photonic and optoelectronic devices. Here we\nanalytically derive the dispersion relation for graphene plasmons on uniaxial\nsubstrates and discuss their momentum, propagation length and polarization as a\nfunction of frequency, propagation direction and both ordinary and\nextraordinary dielectric permittivities of the substrate. We find that the\nplasmons exhibit an anisotropic propagation, yielding radially asymmetric field\npatterns when a point emitter launches plasmons in the graphene layer."
    },
    {
        "anchor": "Signatures of Plexcitonic States in Molecular Electroluminescence: We develop a quantum master equation (QME) approach to investigate the\nelectroluminesence (EL) of molecules confined between metallic electrodes and\ncoupled to quantum plasmonic modes. Within our general state-based framework,\nwe describe electronic tunneling, vibrational damping, environmental dephasing,\nand the quantum coherent dynamics of coupled quantum electromagnetic field\nmodes. As an example, we calculate the STM-induced spontaneous emission of a\ntetraphenylporphyrin (TPP) molecule coupled to a nanocavity plasmon. In the\nweak molecular exciton-plasmon coupling regime we find excellent agreement with\nexperiments, including above-threshold hot luminescence, an effect not\ndescribed by previous semiclassical calculations. In the strong coupling\nregime, we analyze the spectral features indicative of the formation of\nplexcitonic states.",
        "positive": "Notes on steady state current through a noninteracting quantum dot: A pedagogical introduction to matrix Green's function, focusing on its\napplication to steady state transport through discrete-level quantum systems.\nTopics covered in the notes: 1. Retarded Green's function, spectral function\nand density of states 2. LCR system 3. Green's function and spectral function\nof LCR systems 4. Landauer formula and transmission coefficient 5.\nSemi-infinite tight-binding leads and wide-band limit 6. Linear conductance at\nzero temperature 7. Steady state current in a quantum dot: resonance and\ncoherence 8. Steady state current across a tight-binding chain: metal-insulator\ntransitions 9. Steady state current along the edge of a two-dimensional\nlattice: topologically quantized transport"
    },
    {
        "anchor": "Lattice dynamics with molecular Berry curvature: chiral optical phonons: Under the Born-Oppenheimer approximation, the electronic ground state evolves\nadiabatically and can accumulate geometrical phases characterized by the\nmolecular Berry curvature. In this work, we study the effect of the molecular\nBerry curvature on the lattice dynamics in a system with broken time-reversal\nsymmetry. The molecular Berry curvature is formulated based on the\nsingle-particle electronic Bloch states. It manifests as a non-local effective\nmagnetic field in the equations of motion of the ions that are beyond the\nwidely adopted Raman spin-lattice coupling model. We employ the Bogoliubov\ntransformation to solve the quantized equations of motion and to obtain phonon\npolarization vectors. We apply our formula to the Haldane model on a honeycomb\nlattice and find a large molecular Berry curvature around the Brillouin zone\ncenter. As a result, the degeneracy of the optical branches at this point is\nlifted intrinsically. The lifted optical phonons show circular polarizations,\npossess large phonon Berry curvature, and have a nearly quantized angular\nmomentum that modifies the Einstein-de Haas effect.",
        "positive": "Persistent current in an almost staggered Harper model: In this paper we study the persistent current (PC) of a staggered Harper\nmodel, close to the half-filling. The Harper model, which is a quasi-periodic\nsystem, is different than other one dimensional systems with uncorrelated\ndisorder in the fact that it can be in the metallic regime. Nevertheless, the\nPC for a wide range of parameters of the Harper model does not show typical\nmetallic behavior, although the system is in the metallic regime. This is a\nresult of the nature of the central band states, which are a hybridization of\nGaussian states localized in superlattice points. When the superlattice is not\ncommensurate with the system length, the PC behaves as in an insulator. Thus\neven in the metallic regime a typical finite Harper model may exhibit a PC\nexpected from an insulator."
    },
    {
        "anchor": "Non-magnetic defects in the bulk of two-dimensional topological\n  insulators: We found that non-magnetic defects in two-dimensional topological insulators\ninduce bound states of two kinds for each spin orientation: electron- and\nhole-like states. Depending on the sign of the defect potential these states\ncan be also of two kinds with different distribution of the electron density.\nThe density has a maximum or minimum in the center. A surprising effect caused\nby the topological order is a singular dependence of the bound-state energy on\nthe defect potential.",
        "positive": "Dielectric screening of surface states in a topological insulator: Hexagonal warping provides an anisotropy to the dispersion curves of the\nhelical Dirac fermions that exist at the surface of a topological insulator. A\nsub-dominant quadratic in momentum term leads to an asymmetry between\nconduction and valence band. A gap can also be opened through magnetic doping.\nWe show how these various modifications to the Dirac spectrum change the\npolarization function of the surface states and employ our results to discuss\ntheir effect on the plasmons. In the long wavelength limit, the plasmon\ndispersion retains its square root dependence on its momentum,\n$\\boldsymbol{q}$, but its slope is modified and it can acquire a weak\ndependence on the direction of $\\boldsymbol{q}$. Further, we find the existence\nof several plasmon branches, one which is damped for all values of\n$\\boldsymbol{q}$, and extract the plasmon scattering rate for a representative\ncase."
    },
    {
        "anchor": "Charge dynamics and Kondo effect in single electron traps in field\n  effect transistors: We study magneto-electric properties of single electron traps in\nmetal-oxide-semiconductor field effect transistors. Using a microscopic\ndescription of the system based on the single-site Anderson-Holstein model, we\nderive an effective low energy action for the system. The behavior of the\nsystem is characterized by simultaneous polaron tunneling (corresponding to the\ncharging and discharging of the trap) and Kondo screening of the trap spin in\nthe singly occupied state. Hence, the obtained state of the system is a hybrid\nbetween the Kondo regime, typically associated with single electron occupancy,\nand the mixed valence regime, associated with large charge fluctuations. In the\npresence of a strong magnetic field, we demonstrate that the system is\nequivalent to a two level-level system coupled to an Ohmic bath, with a bias\ncontrolled by the applied magnetic field. Due to the Kondo screening, the\neffect of the magnetic field is significantly suppressed in the singly occupied\nstate. We claim that this suppression can be responsible for the experimentally\nobserved anomalous magnetic field dependence of the average trap occupancy in\n${\\rm Si-Si0_2}$ field effect transistors.",
        "positive": "Coherent quantum ratchets driven by tunnel oscillations: Fluctuations\n  and correlations: We study two capacitively coupled double quantum dots focusing on the regime\nin which one double dot is strongly biased, while no voltage is applied to the\nother. Then the latter experiences an effective driving force which induces a\nratchet current, i.e., a dc current in the absence of a bias voltage. Its\ncurrent noise is investigated with a quantum master equation in terms of the\nfull-counting statistics. This reveals, that whenever the ratchet current is\nlarge, it also exhibits some features of a Poissonian process. By eliminating\nthe drive circuit, we obtain a reduced master equation which provides\nanalytical results for the Fano factor."
    },
    {
        "anchor": "Spin-resolved imaging of atomic-scale helimagnetism in monolayer NiI2: Identifying intrinsic noncollinear magnetic order in monolayer van der Waals\n(vdW) crystals is highly desirable for understanding the delicate magnetic\ninteractions at reduced spatial constraints and miniaturized spintronic\napplications, but remains elusive in experiments. Here, we achieved\nspin-resolved imaging of helimagnetism at atomic scale in monolayer NiI2\ncrystals, that were grown on graphene-covered SiC(0001) substrate, using\nspin-polarized scanning tunneling microscopy. Our experiments identify the\nexistence of a spin spiral state with canted plane in monolayer NiI2. The spin\nmodulation Q vector of the spin spiral is determined as (0.2203, 0, 0), which\nis different from its bulk value or its in-plane projection, but agrees well\nwith our first principles calculations. The spin spiral surprisingly indicates\ncollective spin switching behavior under magnetic field, whose origin is\nascribed to the incommensurability between the spin spiral and the crystal\nlattice. Our work unambiguously identifies the helimagnetic state in monolayer\nNiI2, paving the way for illuminating its expected type-II multiferroic order\nand developing spintronic devices based on vdW magnets.",
        "positive": "Berry-Curvature Engineering for Nonreciprocal Directional Dichroism in\n  Two-Dimensional Antiferromagnets: In two-dimensional antiferromagnets, we identify the mixed Berry curvature as\nthe geometrical origin of the nonreciprocal directional dichroism (NDD), which\nrefers to the difference in light absorption with the propagation direction\nflipped. Such a Berry curvature is strongly tied to the uniaxial strain in\naccordance with the symmetry constraint, leading to a highly tunable NDD, whose\nsign and magnitude can be manipulated via the strain direction. As a concrete\nexample, we demonstrate such a phenomenon in a lattice model of MnBi2Te4. The\ncoupling between the mixed Berry curvature and strain also suggests the\nmagnetic quadrupole of the Bloch wave packet as the macroscopic order parameter\nprobed by the NDD in two dimensions, distinct from the multiferroic order P\ntimes M or the spin toroidal and quadrupole order within a unit cell in\nprevious studies. Our work paves the way of the Berry-curvature engineering for\noptical nonreciprocity in two-dimensional antiferromagnets."
    },
    {
        "anchor": "Non-volatile Spin Switch for Boolean and Non-Boolean Logic: We show that the established physics of spin valves together with the\nrecently discovered giant spin-Hall effect could be used to construct Read and\nWrite units that can be integrated into a single spin switch with input-output\nisolation, gain and fan-out similar to CMOS inverters, but with the information\nstored in nanomagnets making it non-volatile. Such spin switches could be\ninterconnected, with no external amplification, just with passive circuit\nelements, to perform logic operations. Moreover, since the digitization and\nstorage occurs naturally in the magnets, the voltages can be used to implement\nanalog weighting for non-Boolean logic.",
        "positive": "Curvature effect on spin polarization in a three-terminal geometry in\n  presence of Rashba spin-orbit interaction: The robust effect of curvature on spin polarization is reported in a\nthree-terminal bridge system where the bridging material is subjected to Rashba\nspin-orbit interaction. The results are examined considering two different\ngeometric configurations, ring- and linear-like, of the material which is\ncoupled to one input and two output leads. Our results exhibit absolute zero\nspin polarization for the linear sample, while finite polarization is obtained\nin output leads for the ring-like sample."
    },
    {
        "anchor": "Aharonov-Bohm Oscillations in a Quasi-Ballistic 3D Topological Insulator\n  Nanowire: In three-dimensional topological insulators (3D TI) nanowires, transport\noccurs via gapless surface states where the spin is fixed perpendicular to the\nmomentum[1-6]. Carriers encircling the surface thus acquire a \\pi Berry phase,\nwhich is predicted to open up a gap in the lowest-energy 1D surface subband.\nInserting a magnetic flux ({\\Phi}) of h/2e through the nanowire should cancel\nthe Berry phase and restore the gapless 1D mode[7-8]. However, this signature\nhas been missing in transport experiments reported to date[9-11]. Here, we\nreport measurements of mechanically-exfoliated 3D TI nanowires which exhibit\nAharonov-Bohm oscillations consistent with topological surface transport. The\nuse of low-doped, quasi-ballistic devices allows us to observe a minimum\nconductance at {\\Phi} = 0 and a maximum conductance reaching e^2/h at {\\Phi} =\nh/2e near the lowest subband (i.e. the Dirac point), as well as the carrier\ndensity dependence of the transport.",
        "positive": "Imaging topological torus lattice from an electron crystal in twisted\n  mono-bilayer graphene: A variety of exotic quantum phases of matter have been created by Van der\nWaals heterostructures. Moreover, these twisted heterostructures provide a\nfeasible way of braiding correlation effect and nontrivial band topology\ntogether. Here, through a comprehensive spectrum study, we report the discovery\nof topological torus lattice in twisted mono-bilayer graphene. The strong\nCoulomb correlations give rise to an unusual charge localization behavior\nwithin the moir\\'e supercell, leading to an electron crystal. The nontrivial\nband topology is encoded into the electron crystal, which would result in\nspatial modulated Chern numbers, and is evidenced by an emergent topological\ntorus lattice state. Our result illustrates an efficient strategy for entwining\nand engineering topological physics with a strong electron correlation."
    },
    {
        "anchor": "Proximity effects in graphene on monolayers of transition-metal\n  phosphorus trichalcogenides MPX$_3$: We investigate the electronic band structure of graphene on a series of\ntwo-dimensional magnetic transition-metal phosphorus trichalcogenide\nmonolayers, MPX$_3$ with M={Mn,Fe,Ni,Co} and X={S,Se}, with first-principles\ncalculations. A symmetry-based model Hamiltonian is employed to extract orbital\nparameters and sublattice resolved proximity-induced exchange couplings\n($\\lambda_{\\textrm{ex}}^\\textrm{A}$ and $\\lambda_{\\textrm{ex}}^\\textrm{B}$)\nfrom the low-energy Dirac bands of the proximitized graphene. Depending on the\nmagnetic phase of the MPX$_3$ layer (ferromagnetic and three antiferromagnetic\nones), completely different Dirac dispersions can be realized with exchange\nsplittings ranging from 0 to 10~meV. Surprisingly, not only the magnitude of\nthe exchange couplings depends on the magnetic phase, but also the global sign\nand the type. Important, one can realize uniform\n($\\lambda_{\\textrm{ex}}^\\textrm{A} \\approx \\lambda_{\\textrm{ex}}^\\textrm{B}$)\nand staggered ($\\lambda_{\\textrm{ex}}^\\textrm{A} \\approx\n-\\lambda_{\\textrm{ex}}^\\textrm{B}$) exchange couplings in graphene. From\nselected cases, we find that the interlayer distance, as well as a transverse\nelectric field are efficient tuning knobs for the exchange splittings of the\nDirac bands. More specifically, decreasing the interlayer distance by only\nabout 10\\%, a giant 5-fold enhancement of proximity exchange is found, while\napplying few V/nm of electric field, provides tunability of proximity exchange\nby tens of percent. We have also studied the dependence on the Hubbard $U$\nparameter and find it to be weak. Moreover, we find that the effect of SOC on\nthe proximitized Dirac dispersion is negligible compared to the exchange\ncoupling.",
        "positive": "Gas transport mechanisms through molecularly thin membranes: Atomically thin molecular carbon nanomembranes (CNMs) with intrinsic\nsub-nanometer porosity are considered as promising candidates for next\ngeneration filtration and gas separation applications due to their extremely\nlow thickness, energy efficiency and selectivity. CNMs are intrinsically porous\nwhich is advantageous over other 2D materials such as graphene and transition\nmetal dichalcogenides where defects and pores need to be introduced after\nsynthesis. It was already discovered that water and helium permeate through\n4,4-terphenylthiol (TPT) CNM above the limit of detection. Additionally, the\npermeation of water vapour was nonlinear against its pressure and 1000 stronger\nthan permeation of helium despite their similar kinetic diameters. However,\nthere was no clear permeation mechanism which could explain permeation of both\nspecies. Here, we demonstrate that permeation of all gas species is defined by\ntheir adsorption. We performed gas permeation measurements through TPT CNM at\ndifferent temperatures and found that all measured gases experienced an\nactivation energy barrier which correlated with their kinetic diameters.\nFurthermore, we identified that entropy loss during adsorption and permeation\nis the fundamental reason of strong nonlinear permeation of water. Our results\nalso demonstrated that adsorption plays a major role in permeation of all\ngases, not just water."
    },
    {
        "anchor": "Band structure and gaps of triangular graphene superlattices: General properties of long wavelength triangular graphene superlattice are\nstudied. It is shown that Dirac points with and without gaps can arise at a\nnumber of high symmetry points of the Brillouin Zone. The existence of gaps can\nlead to insulating behavior at commensurate fillings. Strain and magnetic\nsuperlattices are also discussed.",
        "positive": "Diffraction induced Spin Pumping in\n  Normal-Metal/Multiferroic-Helimagnet/Ferromagnet Heterostructures: Generally the adiabatic quantum pumping phenomenon can be interpreted by the\nsurface integral of the Berry curvature inside the cyclic loop. Spin angular\nmomentum flow without charge current can be pumped out by magnetization\nprecession in ferromagnet-based structures. When an electron is scattered by a\nhelimagnet, spin-dependent diffraction occurs due to the spatial modulation of\nthe spiral. In this work, we consider the charge and spin flow driven by\nmagnetization precession in normal-metal/multiferroic-helimagnet/ferromagnet\nheterostructures. The pumping behavior is governed by the diffracted states.\nGauge dependence in the pumped current was encountered, which does not occur in\nthe static transport properties or pumping behaviors in other systems."
    },
    {
        "anchor": "Electron supercollimation in graphene and Dirac fermion materials using\n  one-dimensional disorder potentials: Electron supercollimation, in which a wavepacket is guided to move\nundistorted along a selected direction, is a highly desirable property that has\nyet been realized experimentally. Disorder in general is expected to inhibit\nsupercollimation. Here, we report a counter-intuitive phenomenon of electron\nsupercollimation by disorder in graphene and related Dirac fermion materials.\nWe show that one can use one-dimensional disorder potentials to control\nelectron wavepacket transport. This is distinct from known systems where an\nelectron wavepacket would be further spread by disorder and hindered in the\npotential fluctuating direction. The predicted phenomenon has significant\nimplications in the understanding and applications of electron transport in\nDirac fermion materials.",
        "positive": "Klein Backscattering and Fabry-Perot Interference in Graphene\n  Heterojunctions: We present a theory of quantum-coherent transport through a lateral p-n-p\nstructure in graphene, which fully accounts for the interference of forward and\nbackward scattering on the p-n interfaces. The backreflection amplitude changes\nsign at zero incidence angle because of the Klein phenomenon, adding a phase\n$\\pi$ to the interference fringes. The contributions of the two p-n interfaces\nto the phase of the interference cancel with each other at zero magnetic field,\nbut become imbalanced at a finite field. The resulting half a period shift in\nthe Fabry-Perot fringe pattern, induced by a relatively weak magnetic field,\ncan provide a clear signature of Klein scattering in graphene. This effect is\nshown to be robust in the presence of spatially inhomogeneous potential of\nmoderate strength."
    },
    {
        "anchor": "Electrical plasmon detection in graphene waveguides: We present a simple device architecture that allows all-electrical detection\nof plasmons in a graphene waveguide. The key principle of our electrical\nplasmon detection scheme is the non-linear nature of the hydrodynamic equations\nof motion that describe transport in graphene at room temperature and in a wide\nrange of carrier densities. These non-linearities yield a dc voltage in\nresponse to the oscillating field of a propagating plasmon. For illustrative\npurposes, we calculate the dc voltage arising from the propagation of the\nlowest-energy modes in a fully analytical fashion. Our device architecture for\nall-electrical plasmon detection paves the way for the integration of graphene\nplasmonic waveguides in electronic circuits.",
        "positive": "Comment on ``New Class of Resonances at the Edge of the Two-Dimensional\n  Electron Gas:'' self-consistent electronic structure: Self-consistent electronic structure calculations, for devices recently\nfabricated and studied by Zhitenev et al. for capacitance spectroscopy in the\nquantum Hall regime, demonstrate that reproducible resonances in the coupling\nbetween adiabatically free edge states and isolated ``puddles'' of electrons of\nhigher filling factor under the gate proceed from an interference phenomenon as\nthe edge states bend upon entering and leaving the gated region. We note that\nresults of experiment and theory which we published earlier this year relate to\na similar, if not identical, phenomenon."
    },
    {
        "anchor": "Lorentz TEM imaging of stripe structures embedded in a soft magnetic\n  matrix: N\\'eel walls in soft magnetic NiFe/NiFeGa hybrid stripe structures surrounded\nby a NiFe film are investigated by high resolution Lorentz transmission\nelectron microscopic imaging. An anti-parallel orientation of magnetization in\n1000 nm wide neighboring unirradiated-irradiated stripes is observed by forming\nhigh angle domain walls during magnetization reversal. Upon downscaling the\nstripe structure size from 1000 nm to 200 nm a transition from a discrete\ndomain pattern to an effective magnetic medium is observed for external\nmagnetic field reversal. This transition is associated with vanishing ability\nof hosting high angle domain walls between adjacent stripes. The investigation\nalso demonstrated the potentiality of Lorentz microscopy to image periodic\nstripe structures well under micron length-scale.",
        "positive": "Trigonal warping and Berry's phase N pi in ABC-stacked multilayer\n  graphene: The electronic band structure of ABC-stacked multilayer graphene is studied\nwithin an effective mass approximation. The electron and hole bands touching at\nzero energy support chiral quasiparticles characterized by Berry's phase N pi\nfor N-layers, generalizing the low-energy band structure of monolayer and\nbilayer graphene. We investigate the trigonal-warping deformation of the energy\nbands and show that the Lifshitz transition, in which the Fermi circle breaks\nup into separate parts at low energy, reflects Berry's phase N pi. It is\nparticularly prominent in trilayers, N=3, with the Fermi circle breaking into\nthree parts at a relatively large energy that is related to next-nearest-layer\ncoupling. For N=3, we study the effects of electrostatic potentials which vary\nin the stacking direction, and find that a perpendicular electric field, as\nwell as opening an energy gap, strongly enhances the trigonal-warping effect.\nIn magnetic fields, the N=3 Lifshitz transition is manifested as a coalescence\nof Landau levels into triply-degenerate levels."
    },
    {
        "anchor": "On the structure and topography of free-standing chemically modified\n  graphene: The mechanical, electrical and chemical properties of chemically modified\ngraphene (CMG) are intrinsically linked to its structure. Here we report on our\nstudy of the topographic structure of free-standing CMG using atomic force\nmicroscopy and electron diffraction. We find that, unlike graphene, suspended\nsheets of CMG are corrugated and distorted on nanometre length scales. AFM\nreveals not only long range (100 nm) distortions induced by the support, as\npreviously observed for graphene, but also short-range corrugations with length\nscales down to the resolution limit of 10 nm. These corrugations are static not\ndynamic, and are significantly diminished on CMG supported on atomically smooth\nsubstrates. Evidence for even shorter range distortions, down to a few\nnanometres or less, is found by electron diffraction of suspended CMG.\nComparison of the experimental data with simulations reveals that the mean\natomic displacement from the nominal lattice position is of order 10% of the\ncarbon-carbon bond length. Taken together, these results suggest a complex\nstructure for chemically modified graphene where heterogeneous\nfunctionalisation creates local strain and distortion.",
        "positive": "Dark-Bright Exciton Splitting Dominates Low-Temperature Diffusion in\n  Halide Perovskite Nanocrystal Assemblies: Semiconductor nanocrystals could replace conventional bulk materials\ncompletely in displays and light-emitting diodes. Exciton transport dominates\nover charge carrier transport for materials with high exciton binding energies\nand long ligands, such as halide perovskite nanocrystal films. Here, we\ninvestigate how beneficial superlattices - nearly perfect 3D nanocrystal\nassemblies of nanocrystals are to exciton transport. Surprisingly, the high\ndegree of order is not as crucial as the individual nanocrystal size, which\nstrongly influences the splitting of the excitonic manifold into bright and\ndark states. At very low temperatures, the energetic splitting is large for the\nsmallest nanocrystals, and dark levels with low oscillator strength effectively\ntrap excitons inside individual nanocrystals, suppressing diffusion. The effect\nis reversed at elevated temperatures, and the larger NC size becomes\ndetrimental to exciton transport due to enhanced exciton trapping and\ndissociation. Our results reveal that the nanocrystal size must be strongly\naccounted for in design strategies of future optoelectronic applications."
    },
    {
        "anchor": "State Initialization of a Hot Spin Qubit in a Double Quantum Dot by\n  Measurement-Based Quantum Feedback Control: A measurement-based quantum feedback protocol is developed for spin state\ninitialization in a gate-defined double quantum dot spin qubit coupled to a\nsuperconducting resonator. The protocol improves qubit state initialization as\nit is able to robustly prepare the spin in shorter time and reach a higher\nfidelity, which can be pre-set. Being able to pre-set the fidelity aimed at is\na highly desired feature enabling qubit initialization to be more\ndeterministic. The protocol developed herein is also effective at high\ntemperatures, which is critical for the current efforts towards scaling up the\nnumber of qubits in quantum computers.",
        "positive": "Exciton radiative lifetime in a monoatomic carbon chain: Linear carbon-based materials such as polyyne and cumulene oligomers provide\na versatile platform for nano-physics and engineering. Direct gap quasi-1D\npolyyne structures are promising for the observation of strong and unusual\nexcitonic eects arising due to the two-dimensional quantum connement. Recently,\nwe reported on the observation of sharp exciton peaks in low temperature\nphotoluminescence spectra of polyyne chains. Here, we analyse the time-resolved\noptical response of this system. We extend the non-local dielectric response\ntheory to predict the exciton radiative lifetime dependence on the band-gap\nvalue and on the length of the chain. A good agreement between the experiment\nand the theory is achieved."
    },
    {
        "anchor": "Improved transfer matrix method without numerical instability: A new improved transfer matrix method (TMM) is presented. It is shown that\nthe method not only overcomes the numerical instability found in the original\nTMM, but also greatly improves the scalability of computation. The new improved\nTMM has no extra cost of computing time as the length of homogeneous scattering\nregion becomes large. The comparison between the scattering matrix method(SMM)\nand our new TMM is given. It clearly shows that our new method is much faster\nthan SMM.",
        "positive": "Bistable hysteresis and resistance switching in hydrogen gold junctions: Current-voltage characteristics of H2-Au molecular junctions exhibit\nintriguing steps around a characteristic voltage of 40 mV. Surprisingly, we\nfind that a hysteresis is connected to these steps with a typical time scale >\n10 ms. This time constant scales linearly with the power dissipated in the\njunction beyond an ofset power P_s = IV_s. We propose that the hysteresis is\nrelated to vibrational heating of both the molecule in the junction and a set\nof surrounding hydrogen molecules. Remarkably, we can engineer our junctions\nsuch that the hysteresis' characteristic time becomes >days. We demonstrate\nthat reliable switchable devices can be built from such junctions."
    },
    {
        "anchor": "Entanglement between static and flying qubits in quantum wires: A weakly bound electron in a semiconductor quantum wire is shown to become\nentangled with an itinerant electron via the coulomb interaction. The degree of\nentanglement and its variation with energy of the injected electron, may be\ntuned by choice of spin and initial momentum. Full entanglement is achieved\nclose to energies where there are spin-dependent resonances. Possible\nrealisations of related device structures are discussed.",
        "positive": "Mechanically-controlled spin-selective transport: A device enabling mechanically-controlled spin and electric transport in\nmesoscopic structures is proposed. It is based on the transfer of electrons\nthrough weak links formed by suspended nanowires, on which the charge carriers\nexperience a strong Rashba spin-orbit interaction that twists their spins. It\nis demonstrated that when the weak link bridges two magnetically-polarised\nelectrodes, a significant spintro-voltaic effect takes place. Then, by\nmonitoring the generated voltage one is able to measure electronic spins\naccumulated in the electrodes, induced e.g., by circularly-polarised light, or\nalternatively, the amount of spin twisting. Mechanically-tuning the device by\nbending the nanowire allows one to achieve full control over the spin\norientations of the charge carriers."
    },
    {
        "anchor": "Resolving the controversy in biexciton binding energy of cesium lead\n  halide perovskite nanocrystals through heralded single-particle spectroscopy: Understanding exciton-exciton interaction in multiply-excited nanocrystals is\ncrucial to their utilization as functional materials. Yet, for lead halide\nperovskite nanocrystals, which are promising candidates for nanocrystal-based\ntechnologies, numerous contradicting values have been reported for the strength\nand sign of their exciton-exciton interaction. In this work we unambiguously\ndetermine the biexciton binding energy in single cesium lead halide perovskite\nnanocrystals at room temperature. This is enabled by the recently introduced\nSPAD array spectrometer, capable of temporally isolating biexciton-exciton\nemission cascades while retaining spectral resolution. We demonstrate that\nCsPbBr$_3$ nanocrystals feature an attractive exciton-exciton interaction, with\na mean biexciton binding energy of 10 meV. For CsPbI$_3$ nanocrystals we\nobserve a mean biexciton binding energy that is close to zero, and individual\nnanocrystals show either weakly attractive or weakly repulsive exciton-exciton\ninteraction. We further show that within ensembles of both materials,\nsingle-nanocrystal biexciton binding energies are correlated with the degree of\ncharge-carrier confinement.",
        "positive": "Observation of geometry dependent conductivity in two-dimensional\n  electron systems: We report electrical conductivity $\\sigma$ measurements on a range of\ntwo-dimensional electron gases (2DEGs) of varying linear extent. Intriguingly,\nat low temperatures ($T$) and low carrier density ($n_{\\mathrm{s}}$) we find\nthe behavior to be consistent with $\\sigma \\sim L^{\\alpha}$, where $L$ is the\nlength of the 2DEG along the direction of transport. Importantly, such\nscale-dependent behavior is precisely in accordance with the scaling hypothesis\nof localization~[Abrahams~\\textit{et al.}, Phys. Rev. Lett. \\textbf{42}, 673\n(1979)] which dictates that in systems where the electronic wave function $\\xi$\nis localized, $\\sigma$ is not a material-specific parameter, but depends on the\nsystem dimensions. From our data we are able to construct the\n\"$\\beta$-function\" $\\equiv (h/e^2) d \\ln \\sigma / d \\ln L$ and show this to be\nstrongly consistent with theoretically predicted limiting values. These results\nsuggest, remarkably, that the electrons in the studied 2DEGs preserve phase\ncoherence over lengths $\\sim~10~\\mu$m. This suggests the utility of the 2DEGs\nstudied towards applications in quantum information as well as towards\nfundamental investigations into many-body localized phases."
    },
    {
        "anchor": "Multiple Andreev reflections in hybrid multiterminal junctions: We investigate theoretically charge transport in hybrid multiterminal\njunctions with superconducting leads kept at different voltages. It is found\nthat multiple Andreev reflections involving several superconducting leads give\nrise to rich subharmonic gap structures in the current-voltage characteristics.\nThe structures are evidenced numerically in junctions in the incoherent regime.",
        "positive": "Quantum Description of Nuclear Spin Cooling in a Quantum Dot: We study theoretically the cooling of an ensemble of nuclear spins coupled to\nthe spin of a localized electron in a quantum dot. We obtain a master equation\nfor the state of the nuclear spins interacting with a sequence of polarized\nelectrons that allows us to study quantitatively the cooling process including\nthe effect of nuclear spin coherences, which can lead to ``dark states'' of the\nnuclear system in which further cooling is inhibited. We show that the\ninhomogeneous Knight field mitigates this effect strongly and that the\nremaining dark state limitations can be overcome by very few shifts of the\nelectron wave function, allowing for cooling far beyond the dark state limit.\nNumerical integration of the master equation indicates, that polarizations\nlarger than 90% can be achieved within a millisecond timescale."
    },
    {
        "anchor": "Andreev bound states in Superconductor-quantum dot Josephson junction at\n  infinite-U limit: Andreev bound states (ABSs) are studied in quantum dot coupled to\nconventional BCS superconducting leads on the basis of effective slave boson\nHamiltonian in an infinite-U (Coulomb interaction) limit followed by Green's\nfunction technique. From the relevant Green's function, density of states (DOS)\nis analyzed at different superconducting phase differences. On the basis of\nnumerical computation, it is pointed out from DOS plot that ABSs (sub-gap\nstates) arise due to the phase difference between left and right\nsuperconducting leads. Due to the dependence on superconducting phase\ndifference, ABSs are current carrying states. We have also analyzed the energy\nof ABSs as a function of phase difference between left and right\nsuperconducting lead for electron hole symmetric as well as non symmetric cases\nat various dot-lead coupling strengths. It is also pointed out that a finite\ninternal gap arises between upper and lower Andreev bound states in the absence\nof electron-hole or left-right symmetry. These results are viewed in the light\nof existing theoretical analysis.",
        "positive": "Current-voltage correlations in interferometers: We investigate correlations of current at contacts and voltage fluctuations\nat voltage probes coupled to interferometers. The results are compared with\ncorrelations of current and occupation number fluctuations at dephasing probes.\nWe use a quantum Langevin approach for the average quantities and their\nfluctuations. For higher order correlations we develop a stochastic path\nintegral approach and find the generating functions of voltage or occupation\nnumber fluctuations. We also derive a generating function for the joint\ndistribution of voltage or occupation number at the probe and current\nfluctuations at a terminal of a conductor. For energy independent scattering we\nfound earlier that the generating function of current cumulants in\ninterferometers with a one-channel dephasing or voltage probe are identical.\nNevertheless, the distribution function for voltage and the distribution\nfunction for occupation number fluctuations differ, the latter being broader\nthan that of former in all examples considered here."
    },
    {
        "anchor": "Dielectric function, screening, and plasmons of graphene in the presence\n  of spin-orbit interactions: We study the dielectric properties of graphene in the presence of Rashba and\nintrinsic spin-orbit interactions in their most general form, i.e., for\narbitrary frequency, wave vector, doping, and spin-orbit coupling (SOC)\nparameters. The main result consists in the derivation of closed analytical\nexpressions for the imaginary as well as for the real part of the polarization\nfunction. Several limiting cases, e.g., the case of purely Rashba or purely\nintrinsic SOC, and the case of equally large Rashba and intrinsic coupling\nparameters are discussed. In the static limit the asymptotic behavior of the\nscreened potential due to charged impurities is derived. In the opposite limit\n($q=0$, $\\omega\\to0$), an analytical expression for the plasmon dispersion is\nobtained and afterwards compared to the numerical result. Our result can also\nbe applied to related systems such as bilayer graphene or topological\ninsulators.",
        "positive": "Spectrum of the Dirac Hamiltonian with the mass-hedgehog in arbitrary\n  dimension: It is shown that the square of the Dirac Hamiltonian with the isotropic\nmass-hedgehog potential in d dimensions is the number operator of fictitious\nbosons and fermions over d quantum states. This result allows one to obtain the\ncomplete spectrum and degeneracies of the Dirac Hamiltonian with the hedgehog\nmass configuration in any dimension. The result pertains to low-energy states\nin the core of a general superconducting or insulating vortex in graphene in\ntwo dimensions, and in the superconducting vortex at the topological - trivial\ninsulator interface in three dimensions, for example. The spectrum in d=2 is\nalso understood in terms of the underlying accidental SU(2) symmetry and the\nsupersymmetry of the Hamiltonian."
    },
    {
        "anchor": "Realizing One-dimensional Metallic States in Graphene via Periodically\n  Coupled Zeroth Pseudo-Landau Levels: Strain-induced pseudo-magnetic fields can mimic real magnetic fields to\ngenerate a zero-magnetic-field analogue of the Landau levels (LLs), i.e., the\npseudo-LLs, in graphene. The distinct nature of the pseudo-LLs enables one to\nrealize novel electronic states beyond that can be feasible with real LLs.\nHere, we report the realization of one-dimensional (1D) metallic states, which\ncan be described well by the Su-Schrieffer-Heeger model, in graphene via\nperiodically coupled zeroth pseudo-LLs. In our experiment, nanoscale strained\nstructures embedded with pseudo-LLs are generated periodically along 1D channel\nof suspended graphene monolayer. Our experiments demonstrate that the zeroth\npseudo-LLs of these strained structures are coupled to form metallic states,\nexhibiting a serpentine pattern that snakes back and forth along the 1D\nsuspended graphene monolayer. These results are verified theoretically by\nlarge-scale tight-binding calculations of the strained samples. Our result\nprovides a new pathway to realize novel quantum states and engineer the\nelectronic properties of graphene by using the localized pseudo-LLs as building\nblocks.",
        "positive": "Rotating edge-field driven processing of chiral spin textures in\n  racetrack devices: Topologically distinct magnetic structures like skyrmions, domain walls, and\nthe uniformly magnetized state have multiple applications in logic devices,\nsensors, and as bits of information. One of the most promising concepts for\napplying these bits is the racetrack architecture controlled by electric\ncurrents or magnetic driving fields. In state-of-the-art racetracks, these\nfields or currents are applied to the whole circuit. Here, we employ\nmicromagnetic and atomistic simulations to establish a concept for racetrack\nmemories free of global driving forces. Surprisingly, we realize that mixed\nsequences of topologically distinct objects can be created and propagated over\nfar distances exclusively by local rotation of magnetization at the sample\nboundaries. We reveal the dependence between the chirality of the rotation and\nthe direction of propagation and define the phase space where the proposed\nprocedure can be realized. The advantages of this approach are the exclusion of\nhigh current and field densities as well as its compatibility with an\nenergy-efficient three-dimensional design."
    },
    {
        "anchor": "Quantization of Conductance in Quasi-Periodic Quantum Wires: We study charge transport in the Peierls-Harper model with a quasi-periodic\ncosine potential. We compute the Landauer-type conductance of the wire. Our\nnumerical results show the following: (i) When the Fermi energy lies in the\nabsolutely continuous spectrum that is realized in the regime of the weak\ncoupling, the conductance is quantized to the universal conductance. (ii) For\nthe regime of localization that is realized for the strong coupling, the\nconductance is always vanishing irrespective of the value of the Fermi energy.\nUnfortunately, we cannot make a definite conclusion about the case with the\ncritical coupling. We also compute the conductance of the Thue-Morse model.\nAlthough the potential of the model is not quasi-periodic, the energy spectrum\nis known to be a Cantor set with zero Lebesgue measure. Our numerical results\nfor the Thue-Morse model also show the quantization of the conductance at many\nlocations of the Fermi energy, except for the trivial localization regime.\nBesides, for the rest of the values of the Fermi energy, the conductance shows\na similar behavior to that of the Peierls-Harper model with the critical\ncoupling.",
        "positive": "Characterization of helical Luttinger liquids in microwave\n  stepped-impedance edge resonators: Coulomb interaction has important consequences on the physics of quantum spin\nHall edge states, weakening the topological protection via two-particle\nscattering and renormalizing both the velocity and charge of collective plasmon\nmodes compared to that of free electrons. Despite these effects, interactions\nremain difficult to quantify. We propose here simple and robust edge resonator\ngeometries to characterize Coulomb interaction by means of high-frequency\nmeasurements. They rely on a transmission line approach, and take advantage of\nthe impedance mismatch between the edge states and their microwave environment."
    },
    {
        "anchor": "Absorption and wavepackets in optically excited semiconductor\n  superlattices driven by dc-ac fields: Within the one-dimensional tight-binding minibands and on-site\n  Coloumbic interaction approximation, the absorption spectrum and coherent\nwavepacket time evolution in an optically excited semiconductor superlattice\ndriven by dc-ac electric fields are investigated using the semiconductor Bloch\nequations.\n  The dominating roles of the ratios of dc-Stark to external ac frequency, as\nwell as ac-Stark to external ac frequency, is emphasized. If the former is an\ninteger ${\\cal N}$, then also ${\\cal N}$ harmonics are present within one Stark\nfrequency, while the fractional case leads to the formation of excitonic\nfractional ladders. The later ratio determines the size and profile of the\nwavepacket. In the absence of excitonic interaction it controls the maximum\nsize wavepackets reach within one cycle, while the interaction produces a\nstrong anisotropy and tends to palliate the dynamic wavepacket localization.",
        "positive": "Higher-order electron-phonon interactions and their effect on the\n  thermal properties of 2D Dirac crystals: To understand the essential properties of Dirac crystals, such as their\nthermal conductivity, we require models that consider the interaction between\nDirac electrons and dispersive acoustic phonons. The exceptionally high thermal\nconductivity in 2D Dirac crystals is attributed to near-ideal phonon quantum\ngases, while undesired limitations arise from electron-phonon (e-ph)\ninteractions which have been shown to limit the thermal conductivity up to\nseveral microns away. The e-ph thermal conductivity is directly linked to the\nphonon scattering rate. Conventional calculations overlook phonons with\nshort-dispersive wavelengths, rendering them inadequate for analyzing 2D Dirac\ncrystals. The phonon scattering rate is typically calculated up to the\nfirst-order magnitude, considering 3-particle interactions involving the decay\nof an electron and phonon (EP-E*) to create a new electron. However, processes\ninvolving the decay of an electron and the creation of a new electron and\nphonon (E-E*P*) are neglected. In this study, we present an accurate expression\nfor the phonon scattering rate and e-ph thermal conductivity in 2D Dirac\ncrystals, accounting for short-dispersive wavelength phonons. We demonstrate\nthe significance of the E-E*P* process even at room temperature in calculating\nthe phonon scattering rate and e-ph thermal conductivity, particularly for\nfirst-order e-ph interactions. Furthermore, we emphasize the importance of\nincorporating second-order e-ph interactions, specifically the EP-E*P*\ninteraction involving the decay of an electron and phonon and the creation of a\nnew electron-phonon pair, to accurately determine the phonon scattering rate\nand e-ph thermal conductivity at high temperatures and low Fermi energies. This\n4-particle interaction process plays a crucial role in characterizing these\nproperties effectively."
    },
    {
        "anchor": "Landau Levels and the Issue of Gauge Invariance in Confined Spaces: We examine the behaviour of a charged particle in a two-dimensional confining\npotential, in the presence of a magnetic field. The confinement serves to\nremove the otherwise infinite degeneracy, but additional ingredients are\nrequired to produce sensible results. We treat both circular and square\ngeometries, and in the latter we explicitly demonstrate the gauge invariance of\nthe energy levels and wave function amplitudes. Both bulk states and edge\nstates are examined, and in the latter case, with sufficiently high quantum\nnumbers we achieve significant differences in the square and circular\ngeometries. Results are achieved using straightforward matrix mechanics, in a\nmanner that is accessible to novices in the field.",
        "positive": "Distinct multiple fermionic states in a single topological metal: Among the quantum materials that gained interest recently are the topological\nDirac/Weyl semimetals, where conduction and valence bands touch at points in\nreciprocal (k)-space, and the Dirac nodal-line semimetals, where these bands\ntouch along a line or a loop in k-space. However, the coexistence of multiple\nfermion phases in one and the same material has not been verified yet. Using\nangle-resolved photoemission spectroscopy (ARPES) and first-principles\nelectronic structure calculations, we systematically study the metallic\ntopological quantum material, Hf2Te2P. Our investigations discover various\nproperties that are rare and never observed in a single Dirac material. We\nobserve the coexistence of both weak and strong topological surface states in\nthe same material and interestingly, at the same momentum position. An\none-dimensional Dirac crossing{the Dirac-node arc-along a high-symmetry\ndirection is revealed by our first-principles calculations and confirmed by our\nARPES measurements. This novel state is associated with the surface bands of a\nweak topological insulator protected by in-plane time-reversal invariance.\nTernary compound Hf2Te2P thus emerges as an intriguing platform to study the\ncoexistence and competition of multi-fermionic states in one material."
    },
    {
        "anchor": "Double Quantum Dot Floquet Gain Medium: Strongly driving a two-level quantum system with light leads to a ladder of\nFloquet states separated by the photon energy. Nanoscale quantum devices allow\nthe interplay of confined electrons, phonons, and photons to be studied under\nstrong driving conditions. Here we show that a single electron in a\nperiodically driven DQD functions as a \"Floquet gain medium,\" where population\nimbalances in the DQD Floquet quasi-energy levels lead to an intricate pattern\nof gain and loss features in the cavity response. We further measure a large\nintra-cavity photon number n_c in the absence of a cavity drive field, due to\nequilibration in the Floquet picture. Our device operates in the absence of a\ndc current -- one and the same electron is repeatedly driven to the excited\nstate to generate population inversion. These results pave the way to future\nstudies of non-classical light and thermalization of driven quantum systems.",
        "positive": "Molecular Dynamic Study of Local Interfacial Thermal Resistance of\n  Solid-Liquid and Solid-Solid Interfaces: Water and Nanotextured Surface: Degradation in performances of air conditioners and refrigerators is caused\nby a frost formation and adhesion on the surface. In the present study, by\nmeans of the classical molecular dynamics simulation, we investigate how and\nhow much the nanotextured surface characteristics, such as surface wettability\nand geometry, influenced the interfacial thermal resistance (ITR) between the\nsolid wall and the water/ice. The ITR of the interfacial region was comparable\nin both the water and the ice states. As the nanostructure gaps became\nnarrower, the ITR of the interfacial region decreased. The local ITR had a weak\nnegative correlation with the local H2O molecule density regardless of the\nphase of the H2O molecules. The local ITR decreased as the local density\nincreased. The greater amount of the thermal energy was transferred through the\nmaterial interface by means of the intermolecular interaction when more the H2O\nmolecules were located in the proximity area, which was closer to the Pt solid\nwall than the first adsorption layer peak. When the H2O molecules were in the\ncrystal form on the solid wall, the proximity molecules decreased, and then the\nlocal ITR significantly increased."
    },
    {
        "anchor": "Extreme renormalisations of dimer eigenmodes by strong light-matter\n  coupling: We explore by theoretical means an extreme renormalisation of the eigenmodes\nof a dimer of dipolar meta-atoms due to strong light-matter interactions.\nFirstly, by tuning the height of an enclosing photonic cavity, we can lower the\nenergy level of the symmetric `bright' mode underneath that of the\nanti-symmetric `dark' mode. This is possible due to the polaritonic nature of\nthe symmetric mode, that shares simultaneously its excitation with the cavity\nand the dimer. For a heterogeneous dimer, we show that the polariton modes can\nbe smoothly tuned from symmetric to anti-symmetric, resulting in a variable\nmode localisation from extended throughout the cavity to concentrated around\nthe vicinity of the dimer. In addition, we reveal a critical point where one of\nthe meta-atoms becomes `shrouded', with no response to a driving electric\nfield, and thus the field re-radiated by the dimer is only that of the other\nmeta-atom. We provide an exact analytical description of the system from first\nprinciples, as well as full-wave electromagnetic simulations that show a strong\nquantitative agreement with the analytical model. Our description is relevant\nfor any physical dimer where dipolar interactions are the dominant mechanism.",
        "positive": "Evidence for the PSL(2$|$2) Wess-Zumino-Novikov-Witten model as a model\n  for the plateau transition in Quantum Hall effect: Evaluation of numerical\n  simulations: In this paper I revise arguments in favour of the PSL(2$|$2)\nWess-Zumino-Novikov-Witten (WZNW) model as a theory of the plateau transition\nin Integer Quantum Hall effect. I show that all available numerical data\n(including the correlation length exponent $\\nu$) are consistent with the\npredictions of such WZNW model with the level $k=8$."
    },
    {
        "anchor": "Chern-Simons Theory of Fractional Quantum Hall Effect in (Pseudo)\n  Massless Dirac Electrons: We derive the effective field theory from the microscopic Hamiltonian of\ninteracting two-dimensional (pseudo) Dirac electrons by performing a statistic\ngauge transformation. The quantized Hall conductance are expected to be\n$\\sigma_{xy}=\\frac{e^2}{h}(2k-1)$ with $k$ is arbitrary integer. There are also\ntopological excitations which have fractional charge and obey fractional\nstatistics.",
        "positive": "Optimal quantum gates for semiconductor qubits: We employ optimal control theory to design optimized quantum gates for\nsolid-state qubits subject to decoherence. At the example of a gate-controlled\nsemiconductor quantum dot molecule we demonstrate that decoherence due to\nphonon couplings can be strongly suppressed. Our results suggest a much broader\nclass of quantum control strategies in solids."
    },
    {
        "anchor": "Adsorption and Intermolecular Interaction of Cobalt Phthalocyanine on\n  CoO(111) Ultrathin Films: An STM and DFT Study: We investigate the adsorption of cobalt phthalocyanine (CoPc) molecules on a\nthin layer of cobalt oxide grown on Ir(100). To that end we compare the results\nof low-temperature scanning tunneling microscopy (STM) with those of ab-initio\ndensity functional theory (DFT) calculations and reveal the adsorption\ngeometry. We find that the CoPc molecules lie flat on the surface and that\ntheir central cobalt atom forms a chemical bond to a substrate oxygen ion.\nHowever, this bond contributes only modestly to the adsorption energy, while\nvan-der-Waals forces dominate the potential landscape and determine to a large\nextend the geometry as well as the distortion of substrate and molecule.\nFurthermore they lead to attractive molecule-molecule interactions at higher\nmolecular coverages. The DFT calculations predict energetic positions of the\nmolecular orbitals which are compared to scanning tunneling spectroscopy (STS)\nmeasurements.",
        "positive": "Decoherence of near-surface nitrogen-vacancy centers due to electric\n  field noise: We show that electric field noise from surface charge fluctuations can be a\nsignificant source of spin decoherence for near-surface nitrogen-vacancy (NV)\ncenters in diamond. This conclusion is based on the increase in spin coherence\nobserved when the diamond surface is covered with high-dielectric-constant\nliquids, such as glycerol. Double resonance experiments show that improved\ncoherence occurs even though the coupling to nearby electron spins is unchanged\nwhen the liquid is applied. Multipulse spin echo experiments reveal the effect\nof glycerol on the spectrum of NV frequency noise."
    },
    {
        "anchor": "Two path transport measurements on a triple quantum dot: We present an advanced lateral triple quantum dot made by local anodic\noxidation. Three dots are coupled in a starlike geometry with one lead attached\nto each dot thus allowing for multiple path transport measurements with two\ndots per path. In addition charge detection is implemented using a quantum\npoint contact. Both in charge measurements as well as in transport we observe\nclear signatures of states from each dot. Resonances of two dots can be\nestablished allowing for serial transport via the corresponding path. Quadruple\npoints with all three dots in resonance are prepared for different electron\nnumbers and analyzed concerning the interplay of the simultaneously measured\ntransport along both paths.",
        "positive": "Dephasing and Measurement Efficiency via a Quantum Dot Detector: We study charge detection and controlled dephasing of a mesoscopic system via\na quantum dot detector (QDD), where the mesoscopic system and the QDD are\ncapacitively coupled. The QDD is considered to have coherent resonant\ntunnelling via a single level. It is found that the dephasing rate is\nproportional to the square of the conductance of the QDD for the Breit-Wigner\nmodel, showing that the dephasing is completely different from the shot noise\nof the detector. The measurement rate, on the other hand, shows a dip near the\nresonance. Our findings are peculiar especially for a symmetric detector in the\nfollowing aspect: The dephasing rate is maximum at resonance of the QDD where\nthe detector conductance is insensitive to the charge state of the mesoscopic\nsystem. As a result, the efficiency of the detector shows a dip and vanishes at\nresonance, in contrast to the single-channel symmetric non-resonant detector\nthat has always a maximum efficiency. We find that this difference originates\nfrom a very general property of the scattering matrix: The abrupt phase change\nexists in the scattering amplitudes in the presence of the symmetry, which is\ninsensitive to the detector current but {\\em stores} the information of the\nquantum state of the mesoscopic system."
    },
    {
        "anchor": "Proximal magnetometry of monolayers of single molecule magnets on gold\n  using polarized muons: The magnetic properties of a monolayer of Fe4 single molecule magnets grafted\nonto a Au (111) thin film have been investigated using low energy muon spin\nrotation. The properties of the monolayer are compared to bulk Fe4. We find\nthat the magnetic properties in the monolayer are consistent with those\nmeasured in the bulk, strongly indicating that the single molecule magnet\nnature of Fe4 is preserved in a monolayer. However, differences in the\ntemperature dependencies point to a small difference in their energy scale. We\nattribute this to a ~60% increase in the intramolecular magnetic interactions\nin the monolayer.",
        "positive": "Tuning the van der Waals Interaction of Graphene with Molecules via\n  Doping: We use scanning tunneling microscopy to visualize and thermal desorption\nspectroscopy to quantitatively measure that the binding of naphthalene\nmolecules to graphene (Gr), a case of pure van der Waals (vdW) interaction,\nstrengthens with $n$- and weakens with $p$-doping of Gr. Density functional\ntheory calculations that include the vdW interaction in a seamless, ab initio\nway accurately reproduce the observed trend in binding energies. Based on a\nmodel calculation, we propose that the vdW interaction is modified by changing\nthe spatial extent of Gr's $\\pi$ orbitals via doping."
    },
    {
        "anchor": "Edge States of \u03b1-Bismuthene Nanostructures: We present a systematic investigation of the edge states of two-dimensional\n{\\alpha}-bismuthene ({\\alpha}-Bi) structures self-assembled on HOPG substrates,\nusing scanning tunnelling microscopy and scanning tunnelling spectroscopy. The\nmeasurements are carried out for 3ML, 5ML and 7ML thick Bi structures. Our\nspectroscopy studies reveal clear features at the edges of the 5ML and 7ML\nthick structures, and the positions of the edge states (ESs) coincide with the\ntopographical step edges. In contrast, in 3ML structures the ESs appear to be\nabsent and instead new states are sometimes observed, far from the\ntopographical edge. These states are associated with a moir\\'e pattern and\nresult from strain-induced modulation of the topology. Our observations\ndemonstrate the impact on the edge states of coupling to adjacent structures.",
        "positive": "Magnetomechanics of mesoscopic wires: We have studied the force in mesoscopic wires in the presence of an external\nmagnetic field along the wire using a free electron model. We show that the\napplied magnetic field can be used to affect the force in the wire. The\nmagnetic field breaks the degeneracy of the eigenenergies of the conduction\nmodes, resulting in more structure in the force as a function of wire length.\nThe use of an external magnetic field is an equilibrium method to control the\nnumber of transporting channels. Under the least favorable circumstances (on\nthe middle of a low conduction step) one needs about 1.3 T, for a mesoscopic\nBismuth wire, to see an abrupt change in the force, at fixed wire length."
    },
    {
        "anchor": "Ambi-chiral anomalous Hall effect in magnetically doped topological\n  insulators: The chirality associated with broken time reversal symmetry in magnetically\ndoped topological insulators has important implications to the quantum\ntransport phenomena. Here we report the anomalous Hall effect studies in Mn-\nand Cr-doped Bi$_2$Te$_3$ topological insulators with varied thickness and\ndoping content. By tracing the chirality of the Hall loops, we find that the\nMn-type anomalous Hall effect with clockwise chirality is strengthened by the\nreduction of film thickness, which is opposite to that of the Cr-type anomalous\nHall effect with counterclockwise chirality. We provide a phenomenological\nmodel to explain the evolution of magnetic order and anomalous Hall effect\nchirality in magnetically doped topological insulators.",
        "positive": "Weak localization in the 2D metallic regime of Si-MOS: The negative magnetoresistance due to weak localization is investigated in\nthe two-dimensional metallic state of Si-MOS structures for high conductance\nvalues between 35 and 120 e^2/h. The extracted phase coherence time is equal to\nthe momentum relaxation time at 10 K but nearly 100 times longer at the lowest\ntemperature. Nevertheless, only weak logarithmic corrections to the\nconductivity are present in the investigated temperature and concentration\nrange thus proving the absence of strong quantum effects due to\nelectron-electron interaction. From saturation effects of the phase coherence\ntime a lower boundary for spin-orbit scattering of about 200 ps is estimated."
    },
    {
        "anchor": "Discovery of a hybrid topological quantum state in an elemental solid: Topology and interactions are foundational concepts in the modern\nunderstanding of quantum matter. Their nexus yields three significant research\ndirections: competition between distinct interactions, as in the multiple\nintertwined phases, interplay between interactions and topology that drives the\nphenomena in twisted layered materials and topological magnets, and the\ncoalescence of multiple topological orders to generate distinct novel phases.\nThe first two examples have grown into major areas of research, while the last\nexample remains mostly untouched, mainly because of the lack of a material\nplatform for experimental studies. Here, using tunneling microscopy,\nphotoemission spectroscopy, and theoretical analysis, we unveil a \"hybrid\" and\nyet novel topological phase of matter in the simple elemental solid arsenic.\nThrough a unique bulk-surface-edge correspondence, we uncover that arsenic\nfeatures a conjoined strong and higher-order topology, stabilizing a hybrid\ntopological phase. While momentum-space spectroscopy measurements show signs of\ntopological surface states, real-space microscopy measurements unravel a unique\ngeometry of topology-induced step edge conduction channels revealed on various\nforms of natural nanostructures on the surface. Using theoretical models, we\nshow that the existence of gapless step edge states in arsenic relies on the\nsimultaneous presence of both a nontrivial strong Z2 invariant and a nontrivial\nhigher-order topological invariant, providing experimental evidence for hybrid\ntopology and its realization in a single crystal. Our discovery highlights\npathways to explore the interplay of different kinds of band topology and\nharness the associated topological conduction channels in future engineered\nquantum or nano-devices.",
        "positive": "GHz Spin Noise Spectroscopy in n-Doped Bulk GaAs: We advance spin noise spectroscopy to an ultrafast tool to resolve high\nfrequency spin dynamics in semiconductors. The optical non-demolition\nexperiment reveals the genuine origin of the inhomogeneous spin dephasing in\nn-doped GaAs wafers at densities at the metal-to-insulator transition. The\nmeasurements prove in conjunction with depth resolved spin noise measurements\nthat the broadening of the spin dephasing rate does not result from thermal\nfluctuations or spin-phonon interaction, as previously suggested, but from\nsurface electron depletion."
    },
    {
        "anchor": "Radiative Lifetimes of Excitons and Trions in Monolayers of Metal\n  Dichalcogenide MoS2: We present results on the radiative lifetimes of excitons and trions in a\nmonolayer of metal dichalcogenide MoS2. The small exciton radius and the large\nexciton optical oscillator strength result in radiative lifetimes in the\n0.18-0.30 ps range for excitons that have small in-plane momenta and couple to\nradiation. Average lifetimes of thermally distributed excitons depend linearly\non the exciton temperature and can be in the few picoseconds range at small\ntemperatures and more than a nanosecond near room temperature. Localized\nexcitons exhibit lifetimes in the same range and the lifetime increases as the\nlocalization length decreases. The radiative lifetimes of trions are in the\nhundreds of picosecond range and increase with the increase in the trion\nmomentum. Average lifetimes of thermally distributed trions increase with the\ntrion temperature as the trions acquire thermal energy and larger momenta. We\nexpect our theoretical results to be applicable to most other 2D transition\nmetal dichalcogenides.",
        "positive": "Interplay of the inverse proximity effect and magnetic field in\n  out-of-equilibrium single-electron devices: The magnetic field is shown to affect significantly non-equilibrium\nquasiparticle (QP) distributions under conditions of inverse proximity effect\non the remarkable example of a single-electron hybrid turnstile. This effect\nsuppresses the gap in the superconducting leads in the vicinity of turnstile\njunctions with a Coulomb blockaded island, thus, trapping hot QPs in this\nregion. Applied magnetic field creates additional QP traps in the form of\nvortices or regions with reduced superconducting gap in the leads resulting in\nrelease of QPs away from junctions. We present clear experimental evidence of\nsuch interplay of the inverse proximity effect and a magnetic field revealing\nitself in the superconducting gap enhancement in a magnetic field as well as in\nsignificant improvement of the turnstile characteristics. The observed\ninterplay of the inverse proximity effect and external magnetic field, and its\ntheoretical explanation in the context of QP overheating are important for\nvarious superconducting and hybrid nanoelectronic devices, which find\napplications in quantum computation, photon detection and quantum metrology."
    },
    {
        "anchor": "Superradiance-like Electron Transport through a Quantum Dot: We theoretically show that intriguing features of coherent many-body physics\ncan be observed in electron transport through a quantum dot (QD). We first\nderive a master equation based framework for electron transport in the\nCoulomb-blockade regime which includes hyperfine (HF) interaction with the\nnuclear spin ensemble in the QD. This general tool is then used to study the\nleakage current through a single QD in a transport setting. We find that, for\nan initially polarized nuclear system, the proposed setup leads to a strong\ncurrent peak, in close analogy with superradiant emission of photons from\natomic ensembles. This effect could be observed with realistic experimental\nparameters and would provide clear evidence of coherent HF dynamics of nuclear\nspin ensembles in QDs.",
        "positive": "Tuning the bandstructure of electrons in a two-dimensional artificial\n  electrostatic crystal in GaAs quantum wells: The electronic properties of solids are determined by the crystal structure\nand interactions between electrons, giving rise to a variety of collective\nphenomena including superconductivity, strange metals and correlated\ninsulators. The mechanisms underpinning many of these collective phenomena\nremain unknown, driving interest in creating artificial crystals which\nreplicate the system of interest while allowing precise control of key\nparameters. Cold atoms trapped in optical lattices provide great flexibility\nand tunability [1, 2], but cannot replicate the long range Coulomb interactions\nand long range hopping that drive collective phenomena in real crystals. Solid\nstate approaches support long range hopping and interactions, but previous\nattempts with laterally patterned semiconductor systems were not able to create\ntunable low disorder artificial crystals, while approaches based on Moire\nsuperlattices in twisted two-dimensional (2D) materials [3, 4] have limited\ntunability and control of lattice geometry. Here we demonstrate the formation\nof highly tunable artificial crystals by superimposing a periodic electrostatic\npotential on the 2D electron gas in an ultrashallow (25 nm deep) GaAs quantum\nwell. The 100 nm period artificial crystal is identified by the formation of a\nnew bandstructure, different from the original cubic crystal and unique to the\nartificial triangular lattice: transport measurements show the Hall coefficient\nchanging sign as the chemical potential sweeps through the artificial bands.\nUniquely, the artificial bandstructure can be continuously tuned from parabolic\nfree-electron bands into linear graphene-like and flat kagome-like bands in a\nsingle device. This approach allows the formation arbitrary geometry 2D\nartificial crystals, opening a new route to studying collective quantum states."
    },
    {
        "anchor": "Carrier-Phonon Scattering Rate and Charge Transport in Spherical and TMV\n  Viruses: The present paper presents the carrier-acoustic phonon scattering in the\nspherical and TMV viruses. We demonstrate theoretically that the absorption\nrate changes in spherical and TMV viruses according to the phonon energy while\nemission of phonon is limited by the hole energy. The obtained relaxation rate\nis then used to calculate the conductivity and mobility of viruses. The\nobtained conductivity for spherical and TMV viruses suggest that the TMV virus\nis more conducting and therefore may be a good candidate for the connector or\nwire to be used in the nanoelectronics. The value of resistance obtained for\nTMV virus is lower than the earlier reported resistance of DNA.",
        "positive": "Water adsorption in ultrathin silica nanotubes: Silica (SiO$_2$) nanotubes (NTs) are used in a wide range of applications\nthat go from sensors to nanofluidics. Currently, these NTs can be grown with\ndiameters as small as 3 nm, with walls 1.5 nm thick. Recent experimental\nadvances combined with first-principles calculations suggest that silica NTs\ncould be obtained from a single silica sheet. In this work, we explore the\nwater adsorption in such ultrathin silica NTs using molecular simulation and\nfirst-principles calculations. Combining molecular dynamics and density\nfunctional theory calculations we obtain putative structures for NTs formed by\n10, 12, and 15-membered SiO$_2$ rings. Water adsorption isotherms for these NTs\nare obtained using Grand Canonical Monte Carlo simulations. Computing the\naccessible cross-section area ($A_\\text{free}$) for the NTs, we were able to\nunderstand how this property correlates with condensation pressures. We found\nthat $A_\\text{free}$ does not necessarily grow with the NT size and that the\nhigher the confinement (smaller $A_\\text{free}$), the larger the condensation\npressure."
    },
    {
        "anchor": "Anomalous Thermodynamic Properties of Electron Accumulation Layer in\n  SrTiO$_{3}$: Due to the nonlinear dielectric response within SrTiO$_{3}$ (STO), an\naccumulation layer created by positive charges at the surface of the STO sample\n($x=0$) has an electron density profile $n(x)$ that slowly decays as\n$1/x^{12/7}$. Here we show that the long tail of $n(x)$ causes the\nmagnetization and the specific heat of the accumulation layer to diverge at\nlarge $x$. We explore the truncation of the tail by the finite sample width\n$W$, the transition from the nonlinear to linear dielectric response with\ndielectric constant $\\kappa$, and the use of a back gate with a negative\nvoltage $-|V|$. We find that both the magnetization and specific heat are\nanomalously large and obey nontrivial power law dependences on $W$, $\\kappa$,\nor $|V|$. We conclude with a discussion of how the capacitance as a function of\nthe back gate voltage may be used to study the shape of the $n(x)$ tail in thin\nsamples.",
        "positive": "Fast preparation of single hole spin in InAs/GaAs quantum dot in Voigt\n  geometry magnetic field: The preparation of a coherent heavy-hole spin via ionization of a\nspin-polarized electron-hole pair in an InAs/GaAs quantum dot in a Voigt\ngeometry magnetic field is investigated. For a dot with a 17 ueV bright-exciton\nfine-structure splitting, the fidelity of the spin preparation is limited to\n0.75, with optimum preparation occurring when the effective fine-structure of\nthe bright-exciton matches the in-plane hole Zeeman energy. In principle,\nhigher fidelities can be achieved by minimizing the bright-exciton\nfine-structure splitting."
    },
    {
        "anchor": "Field electron emission theory (October 2016),v2: This document provides an updated account of material originally presented in\ntwo field electron emission (FE) tutorial lectures given at the 2016 Young\nResearchers' School in Vacuum Micro/Nano Electronics, held in Saint-Petersburg\nin October 2016. The aim of the tutorial lectures was to set out modern\nversions of some of the basics of mainstream FE theory. This paper indicates,\nin some depth, the scope, structure and content of the tutorials, and also\nwhere some of the related published material can be found.",
        "positive": "Feedback and Rate Asymmetry of the Josephson Junction Noise Detector: The Josephson junction noise detector measures the skewness of non-Gaussian\nnoise via the asymmetry of the rate of escape from the zero-voltage state upon\nreversal of the bias current. The feedback of this detector on the noise\ngenerating device is investigated in detail. Concise predictions are made for a\nsecond Josephson junction as noise generating device. The strong nonlinearity\nof this component implies particularly strong feedback effects, including a\nchange of sign of the rate asymmetry as the applied voltage approaches twice\nthe superconducting gap."
    },
    {
        "anchor": "Improved efficiency of heat generation in nonlinear dynamics of magnetic\n  nanoparticles: The deterministic Landau-Lifshitz-Gilbert equation has been used to\ninvestigate the nonlinear dynamics of magnetization and the specific loss power\nin magnetic nanoparticles with uniaxial anisotropy driven by a rotating\nmagnetic field. We propose a new type of applied field, which is\n\"simultaneously rotating and alternating\", i.e. the direction of the rotating\nexternal field changes periodically. We show that a more efficient heat\ngeneration by magnetic nanoparticles is possible with this new type of applied\nfield and we suggest its possible experimental realization in cancer therapy\nwhich requires the enhancement of loss energies.",
        "positive": "Room-temperature quantum emission from interface excitons in\n  mixed-dimensional heterostructures: The development of van der Waals heterostructures has introduced\nunconventional phenomena that emerge at atomically precise interfaces. For\nexample, interlayer excitons in two-dimensional transition metal\ndichalcogenides show intriguing optical properties at low temperatures. Here we\nreport on room-temperature observation of interface excitons in\nmixed-dimensional heterostructures consisting of two-dimensional tungsten\ndiselenide and one-dimensional carbon nanotubes. Bright emission peaks\noriginating from the interface are identified, spanning a broad energy range\nwithin the telecommunication wavelengths. The effect of band alignment is\ninvestigated by systematically varying the nanotube bandgap, and we assign the\nnew peaks to interface excitons as they only appear in type-II\nheterostructures. Room-temperature localization of low-energy interface\nexcitons is indicated by extended lifetimes as well as small excitation\nsaturation powers, and photon correlation measurements confirm single-photon\nemission. With mixed-dimensional van der Waals heterostructures where band\nalignment can be engineered, new opportunities for quantum photonics are\nenvisioned."
    },
    {
        "anchor": "Theory of New Quantum Oscillations in the Magnetoresistance of Graphene\n  Layers: We present a theory presenting new quantum oscillations in the\nmagnetoresistance that are revealed as fine structures superimposed to the\nSchubnikov-de-Haas oscillations. They may be observed in experiments on\ngraphene layers as fine structures that until now seem to have been overseen or\nconsidered to be noise. These oscillations appear also in the behaviour of the\nresistance as a function of the gate voltage that changes the number of\ncarriers or Fermi level. Experimental studies of these resonances should give\ninformation of the uniformity and defects of the samples and represent a new\nfine structure spectroscopy. Also the lateral sample size and quantum effects\nmay explain the absence of magnetoresistance in a few grapheme layers.\nExperiments are proposed.",
        "positive": "Wigner molecules and hybrid qubits: It is demonstrated that exact diagonalization of the microscopic many-body\nHamiltonian via systematic full configuration-interaction (FCI) calculations is\nable to predict the spectra as a function of detuning of three-electron hybrid\nqubits based on GaAs asymmetric double quantum dots. It is further shown that,\nas a result of strong inter-electron correlations, these spectroscopic\npatterns, including avoided crossings between states associated with different\nelectron occupancies of the left and right wells, are inextricably related to\nthe formation of Wigner molecules. These physical entities cannot be captured\nby the previously employed independent-particle or Hubbard-type theoretical\nmodeling of the hybrid qubit. We report remarkable agreement with recent\nexperimental results. Moreover, the present FCI methodology for multi-well\nquantum dots can be straightforwardly extended to treat Si/SiGe hybrid qubits,\nwhere the central role of Wigner molecules was recently experimentally\nconfirmed as well."
    },
    {
        "anchor": "Graphene surpasses GaAs/AlGaAs for the application of the quantum Hall\n  effect in metrology: The quantum Hall effect (QHE) theoretically provides a universal standard of\nelectrical resistance in terms of the Planck constant $h$ and the electron\ncharge $e$. In graphene, the spacing between the lowest discrete energy levels\noccupied by the charge carriers under magnetic field is exceptionally large.\nThis is promising for a quantum Hall resistance standard more practical in\ngraphene than in the GaAs/AlGaAs devices currently used in national metrology\ninstitutes. Here, we demonstrate that large QHE devices, made of high quality\ngraphene grown by propane/hydrogen chemical vapour deposition on SiC\nsubstrates, can surpass state-of-the-art GaAs/AlGaAs devices by considerable\nmargins in their required operational conditions. In particular, in the device\npresented here, the Hall resistance is accurately quantized within $1\\times\n10^{-9}$ over a 10-T wide range of magnetic field with a remarkable lower bound\nat 3.5 T, temperatures as high as 10 K, or measurement currents as high as 0.5\nmA. These significantly enlarged and relaxed operational conditions, with a\nvery convenient compromise of 5 T, 5.1 K and 50 $\\mu$A, set the superiority of\ngraphene for this application and for the new generation of versatile and\nuser-friendly quantum standards, compatible with a broader industrial use. We\nalso measured an agreement of the quantized Hall resistance in graphene and\nGaAs/AlGaAs with an ultimate relative uncertainty of $8.2\\times 10^{-11}$. This\nsupports the universality of the QHE and its theoretical relation to $h$ and\n$e$, essential for the application in metrology, particularly in view of the\nforthcoming Syst\\`eme International d'unit\\'es (SI) based on fundamental\nconstants of physics, including the redefinition of the kilogram in terms of\n$h$.",
        "positive": "Spin-orbit coupling, quantum dots, and qubits in monolayer transition\n  metal dichalcogenides: We derive an effective Hamiltonian which describes the dynamics of electrons\nin the conduction band of transition metal dichalcogenides (TMDC) in the\npresence of perpendicular electric and magnetic fields. We discuss in detail\nboth the intrinsic and the Bychkov-Rashba spin-orbit coupling (SOC) induced by\nan external electric field.\n  We point out interesting differences in the spin-split conduction band\nbetween different TMDC compounds. An important consequence of the strong\nintrinsic SOC is an effective out-of-plane $g$-factor for the electrons which\ndiffers from the free-electron g-factor $g\\simeq 2$. We identify a new term in\nthe Hamiltonian of the Bychkov-Rashba SOC which does not exist in III-V\nsemiconductors. Using first-principles calculations, we give estimates of the\nvarious parameters appearing in the theory.\n  Finally, we consider quantum dots (QDs) formed in TMDC materials and derive\nan effective Hamiltonian which allows us to calculate the magnetic field\ndependence of the bound states in the QDs. We find that all states are both\nvalley and spin split, which suggests that these QDs could be used as\nvalley-spin filters.\n  We explore the possibility of using spin and valley states in TMDCs as\nquantum bits, and conclude that, due to the relatively strong intrinsic\nspin-orbit splitting in the conduction band, the most realistic option appears\nto be a combined spin-valley (Kramers) qubit at low magnetic fields."
    },
    {
        "anchor": "Interaction-Driven Distinctive Electronic States of Artificial Atoms at\n  the ZnO Interface: We have investigated the electronic states of planar quantum dots at the ZnO\ninterface containing a few interacting electrons in an externally applied\nmagnetic field. In these systems, the electron-electron interaction effects are\nexpected to be much stronger than in traditional semiconductor quantum systems,\nsuch as in GaAs or InAs quantum dots. In order to highlight that stronger\nCoulomb effects in the ZnO quantum dots, we have compared the energy spectra\nand the magnetization in this system to those of the InAs quantum dots. We have\nfound that in the ZnO quantum dots, the signatures of stronger Coulomb\ninteraction manifests in an unique ground state that has very different\nproperties than the corresponding ones in the InAs dot. Our results for the\nmagnetization also exhibits behaviors never before observed in a quantum dot:\nWe have found a stronger temperature dependence and other unexpected features,\nsuch as paramagnetic-like behavior at high temperatures for a quantum-dot\nhelium.",
        "positive": "Supercurrent interference in HgTe Josephson junctions: Wires made of topological insulators (TI) are a promising platform for\nsearching for Majorana bound states. These states can be probed by analyzing\nthe fractional ac Josephson effect in Josephson junctions with the TI wire as a\nweak link. An axial magnetic field can be used to tune the system from trivial\nto topologically nontrivial. Here we investigate the oscillations of the\nsupercurrent in such wire Josephson junctions as a function of the axial\nmagnetic field strength and different contact transparencies. Although the\ncurrent flows on average parallel to the magnetic field we observe $h/2e$,\n$h/4e$- and even $h/8e$-periodic oscillations of the supercurrent in samples\nwith lower contact transparencies. Corresponding tight-binding transport\nsimulations using a Bogoliubov-de Gennes model Hamiltonian yield the\nsupercurrent through the Josephson junctions, showing in particular the\npeculiar $h/4e$-periodic oscillations observed in experiments. A further\nsemiclassical analysis based on Andreev-reflected trajectories connecting the\ntwo superconductors allows us to identify the physical origin of these\noscillations. They can be related to flux-enclosing paths winding around the\nTI-nanowire, thereby highlighting the three-dimensional character of the\njunction geometry compared to common planar junctions."
    },
    {
        "anchor": "High temperature electron-hole superfluidity with strong anisotropic\n  gaps in double phosphorene monolayers: Excitonic superfluidity in double phosphorene monolayers is investigated\nusing the BCS mean-field equations. Highly anisotropic superfluidity is\npredicted where we found that the maximum superfluid gap is in the BEC regime\nalong the armchair direction and in the BCS-BEC crossover regime along the\nzigzag direction. We estimate the highest Kosterlitz-Thouless transition\ntemperature with maximum value up to $\\sim 90$ K with onset carrier densities\nas high as $4 \\times 10^{12}$ cm$^{-2}$. This transition temperature is\nsignificantly larger than what is found in double electron-hole few-layers of\ngraphene. Our results can guide experimental research towards the realization\nof anisotropic condensate states in electron-hole phosphorene monolayers.",
        "positive": "Temperature dependence of Andreev spectra in a superconducting carbon\n  nanotube quantum dot: Tunneling spectroscopy of a Nb coupled carbon nanotube quantum dot reveals\nthe formation of pairs of Andreev bound states (ABS) within the superconducting\ngap. A weak replica of the lower ABS is found, which is generated by\nquasi-particle tunnelling from the ABS to the Al tunnel probe. An inversion of\nthe ABS-dispersion is observed at elevated temperatures, which signals the\nthermal occupation of the upper ABS. Our experimental findings are well\nsupported by model calculations based on the superconducting Anderson model."
    },
    {
        "anchor": "Two types of Dirac-cone surface states on (111) surface of topological\n  crystalline insulator SnTe: We have performed angle-resolved photoemission spectroscopy (ARPES) on the\n(111) surface of the topological crystalline insulator SnTe. Distinct from a\npair of Dirac-cone surface states across the X_bar point of the surface\nBrillouin zone on the (001) surface, we revealed two types of Dirac-cone\nsurface states each centered at the G_bar and M_bar points, which originate\nfrom the bulk-band inversion at the L points. We also found that the energy\nlocation of the Dirac point and the Dirac velocity are different from each\nother. This ARPES experiment demonstrates the surface states on different\ncrystal faces of a topological material, and it elucidates how\nmirror-symmetry-protected Dirac cones of a topological crystalline insulator\nshow up on surfaces with different symmetries.",
        "positive": "The role of the Rashba coupling in spin current of monolayer gapped\n  graphene: In the current work we have investigated the influence of the Rashba\nspin-orbit coupling on spin-current of a single layer gapped graphene. It was\nshown that the Rashba coupling has a considerable role in generation of the\nspin-current of vertical spins in mono-layer graphene. The behavior of the\nspin-current is determined by density of impurities. It was also shown that the\nspin-current of the system could increase by increasing the Rashba coupling\nstrength and band-gap of the graphene and the sign of the spin-current could be\ncontrolled by the direction of the current-driving electric field."
    },
    {
        "anchor": "Faraday rotations, ellipticity and circular dichroism in the\n  magneto-optical spectrum of moir\u00e9 superlattices: We study the magneto-optical conductivity of a number of Van der Waals\nheterostructures, namely, twisted bilayer graphene, AB-AB and AB-BA stacked\ntwisted double bilayer graphene and monolayer graphene and AB-stacked bilayer\ngraphene on hexagonal boron nitride. As magnetic field increases, the\nabsorption spectrum exhibits a self-similar recursive pattern reflecting the\nfractal nature of the energy spectrum. Whilst twisted bilayer graphene displays\nonly weak circular dichroism, monolayer graphene and AB-stacked bilayer\ngraphene on hexagonal boron nitride show specifically strong circular\ndichroism, owing to strong inversion symmetry breaking properties of the\nhexagonal boron nitride layer. As, the left and right circularly polarized\nlight interact with these structures differently, plane polarized incident\nlight undergoes a Faraday rotation and gains an ellipticity when transmitted.\nThe size of the respective angles is on the order of a degree.",
        "positive": "Power and efficiency analysis of a realistic resonant tunneling diode\n  thermoelectric: Low-dimensional systems with sharp features in the density of states have\nbeen proposed as a means to improving the efficiency of thermoelectric devices.\nQuantum dot systems, which offer the sharpest density of states achievable,\nhowever, suffer from low power outputs while bulk (3-D) thermoelectrics, while\ndisplaying high power outputs, offer very low efficiencies. Here, we analyze\nthe use of a resonant tunneling diode structure that combines the best of both\naspects, that is, density of states distortion with a finite bandwidth due to\nconfinement that aids the efficiency and a large number of current carrying\ntransverse modes that enhances the total power output. We show that this device\ncan achieve a high power output ($\\sim 0.3$ MW$/m^2$) at efficiencies of $\\sim\n40\\%$ of the Carnot efficiency due to the contribution from these transverse\nmomentum states at a finite bandwidth of $kT/2$. We then provide a detailed\nanalysis of the physics of charge and heat transport with insights on parasitic\ncurrents that reduce the efficiency. Finally, a comparison between the resonant\ntunneling diode and a quantum dot device with comparable bandwidth reveals that\na similar performance requires ultra-dense areal quantum dot densities of $\\sim\n10^{12}/cm^2$."
    },
    {
        "anchor": "Basic concepts in single-molecule electronics: This tutorial outlines the basic theoretical concepts and tools which\nunderpin the fundamentals of phase-coherent electron transport through single\nmolecules. The key quantity of interest is the transmission coefficient T(E),\nwhich yields the electrical conductance, current-voltage relations, the\nthermopower S and the thermoelectric figure of merit ZT of single-molecule\ndevices. Since T(E) is strongly affected by quantum interference (QI), three\nmanifestations of QI in single-molecules are discussed, namely Mach-Zehnder\ninterferometry, Breit-Wigner resonances and Fano resonances. A simple MATLAB\ncode is provided, which allows the novice reader to explore QI in\nmulti-branched structures described by a tight-binding (Huckel) Hamiltonian.\nMore generally, the strengths and limitations of materials-specific transport\nmodelling based on density functional theory are discussed.",
        "positive": "High-performance solution of the transport problem in a graphene\n  armchair structure with a generic potential: We propose an efficient numerical method to study the transport properties of\narmchair graphene ribbons in the presence of a generic external potential. The\nmethod is based on a continuum envelope-function description with physical\nboundary conditions. The envelope functions are computed in the reciprocal\nspace, and the transmission is then obtained with a recursive scattering matrix\napproach. This allows a significant reduction of the computational time with\nrespect to finite difference simulations."
    },
    {
        "anchor": "Tailoring Elastic Scattering of Relativistic Antiferromagnetic Domain\n  Walls for Collision-based Computing: Soliton-based computing is relied on their unique properties for transporting\nenergy and emerging intact from head-on collisions. Magnetic domain walls are\noften referred to as solitons disregarding the strict mathematical definition\nrequiring the above scattering property. Here we demonstrate the conditions of\nelastic and inelastic scattering for spin-orbit torque-induced dynamics of\nantiferromagnetic domain walls on the example of a technologically relevant\nMn$_2$Au material. We show that even domain walls with opposite winding numbers\ncan experience elastic scattering and we present a corresponding phase diagram\nas a function of the spin-orbit field strength and duration. The elastic\ncollision requires minimum domain walls speed which we explain assuming an\nattractive potential created by domain wall pair. On the contrary, when the\ndomain walls move at lower speeds, their collision is inelastic and results in\na dispersing breather. Our findings will be important for the development\nsoliton-based computing using antiferromagnetic spintronics and we discuss\nthese perspective on our suggestions of how to create NOT and XOR gates.",
        "positive": "Tunneling in rippled graphene superlattice with spin dependence and a\n  mass term: The insertion of the band gap $\\Delta$ in the rippled graphene superlattice\nleads to new outcomes, as demonstrated. The essential thing is the appearance\nof opposite-spin transmissions, which increase with $\\Delta$ and vanish without\nit. Furthermore, compared to the $\\Delta=0$ scenario, the duration of the\nsuppression of the transmission with the same spin is longer, with many peaks.\nThe maximum value of transmissions with the same spin declines and remains\naround unity. Furthermore, for particular energy values, a shift in the\nbehavior of the transmission channels is found. As a result, we demonstrate\nthat with $\\Delta$, transmission filtering becomes crucial. Finally, as a\nresult of the band gap, distinct variations in total conductance are\ndiscovered."
    },
    {
        "anchor": "Observation of quantum-limited heat conduction over macroscopic\n  distances: The emerging quantum technological apparatuses [1,2], such as the quantum\ncomputer [3-5], call for extreme performance in thermal engineering at the\nnanoscale [6]. Importantly, quantum mechanics sets a fundamental upper limit\nfor the flow of information and heat, which is quantified by the quantum of\nthermal conductance [7,8]. The physics of this kind of quantum-limited heat\nconduction has been experimentally studied for lattice vibrations, or phonons\n[9], for electromagnetic interactions [10], and for electrons [11]. However,\nthe short distance between the heat-exchanging bodies in the previous\nexperiments hinders the applicability of these systems in quantum technology.\nHere, we present experimental observations of quantum-limited heat conduction\nover macroscopic distances extending to a metre. We achieved this striking\nimprovement of four orders of magnitude in the distance by utilizing microwave\nphotons travelling in superconducting transmission lines. Thus it seems that\nquantum-limited heat conduction has no fundamental restriction in its distance.\nThis work lays the foundation for the integration of normal-metal components\ninto superconducting transmission lines, and hence provides an important tool\nfor circuit quantum electrodynamics [12-14], which is the basis of the emerging\nsuperconducting quantum computer [15]. In particular, our results demonstrate\nthat cooling of nanoelectronic devices can be carried out remotely with the\nhelp of a far-away engineered heat sink. In addition, quantum-limited heat\nconduction plays an important role in the contemporary studies of\nthermodynamics such as fluctuation relations and Maxwell's demon [16,17]. Here,\nthe long distance provided by our results may, for example, lead to an ultimate\nefficiency of mesoscopic heat engines with promising practical applications\n[18].",
        "positive": "Interplay of pulse duration, peak intensity, and particle size in\n  laser-driven electron emission from silica nanospheres: We present the results of a systematic study of photoelectron emission from\ngasphase dielectric nanoparticles (SiO2) irradiated by intense 25 fs, 780 nm\nlinearly polarized laser pulses as a function of particle size (20 nm to 750 nm\nin diameter) and laser intensity. We also introduce an experimental technique\nto reduce the effects of focal volume averaging. The highest photoelectron\nenergies show a strong size dependence, increasing by a factor of six over the\nrange of particles sizes studied at a fixed intensity. For smaller particle\nsizes (up to 200 nm), our findings agree well with earlier results obtained\nwith few-cycle, ~4 fs pulses. For large nanoparticles, which exhibit stronger\nnear-field localization due to field-propagation effects, we observe the\nemission of much more energetic electrons, reaching energies up to ~200 times\nthe ponderomotive energy. This strong deviation in maximum photoelectron energy\nis attributed to the increase in ionization and charge interaction for\nmany-cycle pulses at similar intensities."
    },
    {
        "anchor": "Spin polarized nematic order, quantum valley Hall states, and field\n  tunable topological transitions in twisted multilayer graphene systems: We theoretically study the correlated insulator states, quantum anomalous\nHall (QAH) states, and field-induced topological transitions between different\ncorrelated states in twisted multilayer graphene systems. Taking twisted\nbilayer-monolayer graphene and twisted double-bilayer graphene as examples, we\nshow that both systems stay in spin polarized, $C_{3z}$-broken insulator states\nwith zero Chern number at 1/2 filling of the flat bands under finite\ndisplacement fields. In some cases these spin polarized, nematic insulator\nstates are in the quantum valley Hall phase by virtue of the nontrivial band\ntopology of the systems. The spin polarized insulator state is quasi-degenerate\nwith the valley polarized state if only the dominant intra-valley Coulomb\ninteraction is included. Such quasi-degeneracy can be split by atomic on-site\ninteractions such that the spin polarized, nematic state become the unique\nground state. Such a scenario applies to various twisted multilayer graphene\nsystems at 1/2 filling, thus can be considered as a universal mechanism.\nMoreover, under vertical magnetic fields, the orbital Zeeman splittings and the\nfield-induced change of charge density in twisted multilayer graphene systems\nwould compete with the atomic Hubbard interactions, which can drive transitions\nfrom spin polarized zero-Chern-number states to valley-polarized QAH states\nwith small onset magnetic fields.",
        "positive": "Analysis of doorway states in a graphene structure: Doorway states, which are related to the strength function phenomenon and\ngiant resonances, arise when two systems interact, one with a high density\neigenvalue spectrum and the other with a comparatively low density. These\nconcepts, first studied in nuclear physics in the 40's, are here analyzed from\na theoretical point of view in special and simple graphene structures, obtained\nafter applying appropriate voltages to a graphene sheet. The influence of the\ndoorway states on the electronic transport in these systems is also studied. To\nanalyze these effects we consider a two-dimensional model of two potential\nbarriers of equal height but very different widths separated by a well."
    },
    {
        "anchor": "Quasi-spin Model for Macroscopic Quantum Tunnelling between Two Coupled\n  Bose-Einstein Condensates: The macroscopic quantum tunneling between two coupled Bose-Einstein\ncondensates (BEC) (radio-frequency coupled two-component BECs or two BECs\nconfined in a double-well potential) is mapped onto the tunneling of an\nuniaxial spin with an applied magnetic field. The tunneling exponent is\ncalculated with an imaginary-time path-integral method. In the limit of low\nbarrier, the dependence of tunneling exponent on the system parameters is\nobtained, and the crossover temperature from thermal regime to quantum regime\nis estimated. The detailed information about the tunnelling will give help to\ncontrol population conversion between coupled BECs and realize quantum\ncomputation with coupled BECs.",
        "positive": "Fractional Quantum Hall Effect States on a Torus show a Liquid Insulator\n  Direct Transition: From the Fractional Quantum Hall Effect States on a torus with filling factor\nnu = 1/p, p odd, we found that for small values of nu such states describe\ntriangular Wigner crystals which are stable configurations. Therefore, the\ninsulator phase of the two-dimensional electron system can be described with\nthe same wave function that the liquid phase, and the incompressible liquid\nfreezes (or the Wigner crystal melts) without any quantum transition between\nstates, thus the system phase changes by means of a direct transition. We found\nat least one stable configuration of a Wigner crystal with F = 3 electrons for\ncell and we investigate the behavior of the crystal when the lengths ratio\nLy/Lx changes."
    },
    {
        "anchor": "Spin structure and spin magnetic susceptibility of two-dimensional\n  Wigner clusters: Spin states of two-dimensional Wigner clusters are considered at low\ntemperatures, when all electrons are in ground coordinate states. The spin\nsubsystem behavior is determined by antiferromagnetic exchange integrals. The\nspin states in such a system in the presence of a magnetic field are described\nin terms of the Ising model. The spin structure, correlation function, and\nmagnetic susceptibility of the cluster are found by computer simulations. It is\nshown that the spin susceptibility experiences oscillations with respect to the\nmagnetic field, owing to the magnetoinduced spin subsystem rearrangements.",
        "positive": "Universal Fermi liquid crossover and quantum criticality in a mesoscopic\n  device: Quantum critical systems derive their finite temperature properties from the\ninfluence of a zero temperature quantum phase transition. The paradigm is\nessential for understanding unconventional high-Tc superconductors and the\nnon-Fermi liquid properties of heavy fermion compounds. However, the\nmicroscopic origins of quantum phase transitions in complex materials are often\ndebated. Here we demonstrate experimentally, with support from numerical\nrenormalization group calculations, a universal crossover from quantum critical\nnon-Fermi liquid behavior to distinct Fermi liquid ground states in a highly\ncontrollable quantum dot device. Our device realizes the non-Fermi liquid\ntwo-channel Kondo state, based on a spin-1/2 impurity exchange-coupled equally\nto two independent electronic reservoirs. Arbitrarily small detuning of the\nexchange couplings results in conventional screening of the spin by the more\nstrongly coupled channel for energies below a Fermi liquid scale T*. We extract\na quadratic dependence of T* on gate voltage close to criticality and validate\nan asymptotically exact description of the universal crossover between strongly\ncorrelated non-Fermi liquid and Fermi liquid states."
    },
    {
        "anchor": "Single-mode phonon transmission in symmetry broken carbon nanotubes: Normal mode phonon transmissions are studied in carbon nanotubes with the\npresence of Stone-Wales (SW) defect, using a mode-matching method and through\nthe analysis of symmetry. The calculation shows that the transmission for low\ngroup velocity acoustic phonons is evidently reduced at high frequency range,\nand that this SW defect induced symmetry breaking strongly inhibits the\ntransmission of long wave optical phonons in carbon nanotubes. The\ncharacteristic features of transmission for each phonon mode depend on the\nsymmetry. These findings suggest that the local heating in the defective\nnanotubes may be contributed mainly from the low group velocity acoustic\nphonons and optical phonons near the $\\Gamma$-point.",
        "positive": "Coherent Stimulated X-ray Raman Spectroscopy; Attosecond Extension of\n  RIXS: Spontaneous and stimulated resonant inelastic X-ray Raman scattering signals\nare calculated using the Keldysh-Schwinger closed-time path loop and expressed\nas overlaps of Doorway and Window electron-hole wavepackets. These are recast\nin terms of the one-particle Green's functions and expansion coefficients of\nconfiguration interaction singles for valence excitations, which can be\nobtained from standard electronic structure codes. Calculation for many-body\nstates of ground and core-excited system is avoided."
    },
    {
        "anchor": "Structural spillage: an efficient method to identify non-crystalline\n  topological materials: While topological materials are not restricted to crystals, there is no\nefficient method to diagnose topology in non-crystalline solids such as\namorphous materials. Here we introduce the structural spillage, a new indicator\nthat predicts the unknown topological phase of a non-crystalline solid, which\nis compatible with first-principles calculations. We illustrate its potential\nwith tight-binding and first-principles calculations of amorphous bismuth,\npredicting a bilayer to be a new topologically nontrivial material. Our work\nopens up the efficient prediction of non-crystalline solids via\nfirst-principles and high-throughput searches.",
        "positive": "Transport properties of a molecular quantum dot coupled to\n  one-dimensional correlated electrons: We analyze the transport properties of a quantum dot with a harmonic degree\nof freedom (Holstein phonon) coupled to interacting one-dimensional metallic\nleads. Using Tomonaga-Luttinger model to describe the interacting leads we\nconstruct the generating function of the full counting statistics (FCS) for a\nspecific constellation of system parameters and give explicit expression for\nthe cumulant generating function. In the resonant case we find the lowest order\ncorrection to the current to be negative and divergent when source-drain\nvoltage approaches the phonon frequency. Via a diagram resummation procedure we\nshow, that this divergencies can be repealed. On the contrary, in the\noff-resonant case the lowest order correction remains finite. This effect can\nbe traced back to the strongly non-monotonic behaviour of the bare transmission\ncoefficient (without phonon) with respect to the dot level energy. We calculate\ncorrections to the noise power as well and discuss possible experimental\nimplications of this phenomenon."
    },
    {
        "anchor": "Andreev spin qubits in multichannel Rashba nanowires: We theoretically analyze the Andreev bound states and their coupling to\nexternal radiation in superconductor-nanowire-superconductor Josephson\njunctions. We provide an effective Hamiltonian for the junction projected onto\nthe Andreev level subspace and incorporating the effects of nanowire\nmultichannel structure, Rashba spin-orbit coupling, and Zeeman field. Based on\nthis effective model, we investigate the dependence of the Andreev levels and\nthe matrix elements of the current operator on system parameters such as\nchemical potential, nanowire dimensions, and normal transmission. We show that\nthe combined effect of the multichannel structure and the spin-orbit coupling\ngives rise to finite current matrix elements between odd states having\ndifferent spin polarizations. Moreover, our analytical results allow to\ndetermine the appropriate parameters range for the detection of transitions\nbetween even as well as odd states in circuit QED like experiments, which may\nprovide a way for the Andreev spin qubit manipulation.",
        "positive": "Real-space observation of short-period cubic lattice of skyrmions in\n  MnGe: Emergent phenomena and functions arising from topological electron-spin\ntextures in real space or momentum space are attracting growing interest for\nnew concept of states of matter as well as for possible applications to\nspintronics. One such example is a magnetic skyrmion, a topologically stable\nnanoscale spin vortex structure characterized by a topological index.\nReal-space regular arrays of skyrmions are described by combination of\nmulti-directional spin helixes. Nanoscale configurations and characteristics of\nthe two-dimensional skyrmion hexagonal-lattice have been revealed extensively\nby real-space observations. Other three-dimensional forms of skyrmion lattices,\nsuch as a cubic-lattice of skyrmions, are also anticipated to exist, yet their\ndirect observations remain elusive. Here we report real-space observations of\nspin configurations of the skyrmion cubic-lattice in MnGe with a very short\nperiod (~3 nm) and hence endowed with the largest skyrmion number density. The\nskyrmion lattices parallel to the {100} atomic lattices are directly observed\nusing Lorentz transmission electron microscopes (Lorentz TEMs). It enables the\nfirst simultaneous observation of magnetic skyrmions and underlying\natomic-lattice fringes. These results indicate the emergence of\nskyrmion-antiskyrmion lattice in MnGe, which is a source of emergent\nelectromagnetic responses and will open a possibility of controlling\nfew-nanometer scale skyrmion lattices through atomic lattice modulations."
    },
    {
        "anchor": "Absorption of acoustic phonons in Fluorinated Carbon Nanotubes with\n  non-parabolic, double periodic band: We studied theoretically the absorption of acoustic phonons in the hypersound\nregime in Fluorine modified Carbon Nanotube (F-CNT) $\\Gamma_q^{F-CNT}$ and\ncompared it to that of undoped Single Walled Nanotube (SWNT) $\\Gamma_q^{SWNT}$.\nPer the numerical analysis, the F-CNT showed less absorption to that of SWNT\nthus $\\vert\\Gamma_q^{F-CNT}\\vert < \\vert\\Gamma_q^{SWNT}\\vert $. This is due to\nthe fact that Fluorine is highly electronegative and weakens the walls of the\nSWNT. Thus, the $\\pi$-electrons associated with to the Fluorine which causes\nless free charge carriers to interact with the phonons and hence changing the\nmetallic properties of the SWNT to semiconductor by the doping process. From\nthe graphs obtained, the ratio of hypersound absorption in SWNT to F-CNT at $T\n= 45K$ is $\\frac{\\Gamma_{(SWNT)}}{\\Gamma_{(F-CNT)}}\\approx 29$ whilst at $T =\n55K$, is $\\frac{\\Gamma_{(SWNT)}}{\\Gamma_{(F-CNT)}}\\approx 9$ and at $T = 65K$,\nis $\\frac{\\Gamma_{(SWNT)}}{\\Gamma_{(F-CNT)}}\\approx 2$. Clearly, the ratio\ndecreases as the temperature increases.",
        "positive": "Spin Hall effects without spin currents in magnetic insulators: The spin Hall effect (SHE) is normally discussed in terms of a spin current,\nwhich is ill-defined in strongly spin-orbit-coupled systems because of spin\nnon-conservation. In this work we propose an alternative view of SHE phenomena\nby relating them to a spin analog of charge polarization induced by an electric\nfield. The spin density polarization is most conveniently defined in\ninsulators, which can have a SHE if they break time-reversal symmetry, i.e. if\nthey are magnetic. The reciprocal of this SHE is a counterpart of the inverse\nSHE (ISHE), and is manifested in magnetic insulators as a charge polarization\ninduced by a Zeeman field gradient. We use a modified Kane-Mele model to\nillustrate the magnetic spin Hall effect, and to discuss its bulk-boundary\nrelationship."
    },
    {
        "anchor": "Density functional theory of the phase diagram of maximum density\n  droplets in two-dimensional quantum dots in a magnetic field: We present a density-functional theory (DFT) approach to the study of the\nphase diagram of the maximum density droplet (MDD) in two-dimensional quantum\ndots in a magnetic field. Within the lowest Landau level (LLL) approximation,\nanalytical expressions are derived for the values of the parameters $N$ (number\nof electrons) and $B$ (magnetic field) at which the transition from the MDD to\na ``reconstructed'' phase takes place. The results are then compared with those\nof full Kohn-Sham calculations, giving thus information about both correlation\nand Landau level mixing effects. Our results are also contrasted with those of\nHartree-Fock (HF) calculations, showing that DFT predicts a more compact\nreconstructed edge, which is closer to the result of exact diagonalizations in\nthe LLL.",
        "positive": "Quantized quasinormal mode description of non-linear cavity QED effects\n  from coupled resonators with a Fano-like resonance: We employ a recently developed quantization scheme for quasinormal modes\n(QNMs) to study a nonperturbative open cavity-QED system consisting of a hybrid\nmetal-dielectric resonator coupled to a quantum emitter. This hybrid cavity\nsystem allows one to explore the complex coupling between a low $Q$ (quality\nfactor) resonance and a high $Q$ resonance, manifesting in a striking Fano\nresonance, an effect that is not captured by traditional quantization schemes\nusing normal modes or a Jaynes-Cummings (JC) type model. The QNM quantization\napproach rigorously includes dissipative coupling between the QNMs, and is\nsupplemented with generalized input-output relations for the output electric\nfield operator for multiple modes in the system, and correlation functions\noutside the system. The role of the dissipation-induced mode coupling is\nexplored in the strong coupling regime between the photons and emitter beyond\nthe first rung of the JC dressed-state ladder. Important differences in the\nquantum master equation and input-output relations between the QNM quantum\nmodel and phenomenological dissipative JC models are found. In a second step,\nnumerical results for the Fock distributions and system as well as output\ncorrelation functions obtained from the quantized QNM model for the hybrid\nstructure are compared with results from a phenomenological approach. We\ndemonstrate explicitly how the quantized QNM model manifests in multiphoton\nquantum correlations beyond what is predicted by the usual JC models."
    },
    {
        "anchor": "Quantized electrochemical transport in Weyl semimetals: We show that under the effect of an external electric field and a gradient of\nchemical potential, a topological electric current can be induced in Weyl\nsemimetals without inversion and mirror symmetries. We derive analytic\nexpressions for the nonlinear conductivity tensor and show that it is nearly\nquantized for small tilting when the Fermi levels are close to the Weyl nodes.\nWhen the van Hove point is much larger than the largest Fermi level, the band\nstructure is described by two linearly dispersing Weyl fermions with opposite\nchirality. In this case, the electrochemical response is fully quantized in\nterms of fundamental constants and the scattering time, and it can be used to\nmeasure directly the topological charge of Weyl points. We show that the\nelectrochemical chiral current may be derived from an electromagnetic action\nsimilar to axion electrodynamics, where the position-dependent chiral Fermi\nlevel plays the role of the axion field. This posits our results as a direct\nconsequence of the chiral anomaly.",
        "positive": "Non-local magnon-based transport in yttrium iron garnet/platinum\n  heterostructures at high temperatures: The spin Hall effect in a heavy metal thin film allows to probe the magnetic\nproperties of an adjacent magnetic insulator via magnetotransport measurements.\nHere, we investigate the magnetoresistive response of yttrium iron\ngarnet/platinum heterostructures from room temperature to beyond the Curie\ntemperature $T_\\mathrm{C, YIG} \\approx 560\\,\\mathrm{K}$ of the ferrimagnetic\ninsulator. We find that the amplitude of the (local) spin Hall\nmagnetoresistance decreases monotonically from $300\\,\\mathrm{K}$ towards\n$T_\\mathrm{C}$, mimicking the evolution of the saturation magnetization of\nyttrium iron garnet. Interestingly, the spin Hall magnetoresistance vanishes\naround $500\\,\\mathrm{K}$, well below $T_\\mathrm{C}$, which we attribute to the\nformation of a parasitic interface layer by interdiffusion. Around room\ntemperature the non-local magnon-mediated magnetoresistance exhibits a power\nlaw scaling $T^{\\alpha}$ with $\\alpha = 3/2$, as already reported. The exponent\ndecreases gradually to $\\alpha \\sim 1/2$ at around $420\\,\\mathrm{K}$, before\nthe non-local magnetoresistance vanishes rapidly at a similar temperature as\nthe spin Hall magnetoresistance. We attribute the reduced $\\alpha$ at high\ntemperatures to the increasing thermal magnon population which leads to\nenhanced scattering of the non-equilibrium magnon population and a reduced\nmagnon diffusion length. Finally, we find a magnetic field independent offset\nvoltage in the non-local signal for $T > 470\\,\\mathrm{K}$ which we associate\nwith electronic leakage currents through the normally insulating yttrium iron\ngarnet film. Indeed, this non-local offset voltage is thermally activated with\nan energy close to the band gap."
    },
    {
        "anchor": "Effect of surface disorder on the chiral surface states of a\n  three-dimensional quantum Hall system: We investigate the effect of surface disorder on the chiral surface states of\na three-dimensional quantum Hall system. Utilizing a transfer-matrix method, we\nfind that the localization length of the surface state along the magnetic field\ndecreases with the surface disorder strength in the weak disorder regime, but\nincreases anomalously in the strong disorder regime. In the strong disorder\nregime, the surface states mainly locate at the first inward layer to avoid the\nstrong disorder in the outmost layer. The anomalous increase of the\nlocalization length can be explained by an effective model, which maps the\nstrong disorder on the surface layer to the weak disorder on the first inward\nlayer. Our work demonstrates that surface disorder can be an effective way to\ncontrol the transport behavior of the surface states along the magnetic field.\nWe also investigate the effect of surface disorder on the full distribution of\nconductances P(g) of the surface states in the quasi-one-dimensional (1D)\nregime for various surface disorder strengths. In particular, we find that P(g)\nis Gaussian in the quasi-1D metal regime and log-normal in the quasi-1D\ninsulator regime. In the crossover regime, P(g) exhibits highly nontrivial\nforms, whose shapes coincide with the results obtained from the\nDorokhov-Mello-Pereyra-Kumar equation of a weakly disordered quasi-1D wire in\nthe absence of time-reversal symmetry. Our results suggest that P(g) is fully\ndetermined by the average conductance, independent of the details of the\nsystem, in agreement with the single-parameter scaling hypothesis.",
        "positive": "Electronic Structure of an Iron-Porphyrin Derivative on Au(111): Surface-bound porphyrins are promising candidates for molecular switches,\nelectronics and spintronics. Here, we studied the structural and the electronic\nproperties of Fe-tetra-pyridil-porphyrin adsorbed on Au(111) in the monolayer\nregime. We combined scanning tunneling microscopy/spectroscopy, ultraviolet\nphotoemission, and two-photon photoemission to determine the energy levels of\nthe frontier molecular orbitals. We also resolved an excitonic state with a\nbinding energy of 420 meV, which allowed us to compare the electronic transport\ngap with the optical gap."
    },
    {
        "anchor": "Effect of Monolayer Thickness Fluctuations on Coherent Exciton Coupling\n  in Single Quantum Wells: Monolayer fluctuations in the thickness of a semiconductor quantum well (QW)\nlead to three types of excitons, located in the narrower, average and thicker\nregions of the QW, which are clearly resolved in optical spectra. Whether or\nnot these excitons are coherently coupled via Coulomb interactions is a\nlong-standing debate. We demonstrate that different types of disorder in QWs\ndistinctly affects the coherent coupling and that the coupling strength can be\nquantitatively measured using optical two-dimensional Fourier transform\nspectroscopy. We prove experimentally and theoretically that in narrow quantum\nwells the coherent coupling occurs predominantly between excitons residing in\nthe disorder-free areas of the QWs and those residing in the plateau-type\ndisorder. In contrast, excitons localized in the fault-type disorder potentials\ndo not coherently couple to other excitons.",
        "positive": "Understanding Polarization Properties of InAs Quantum Dots by Atomistic\n  Modeling of Growth Dynamics: A model for realistic InAs quantum dot composition profile is proposed and\nanalyzed, consisting of a double region scheme with an In-rich internal core\nand an In-poor external shell, in order to mimic the atomic scale phenomena\nsuch as In-Ga intermixing and In segregation during the growth and overgrowth\nwith GaAs. The parameters of the proposed model are derived by reproducing the\nexperimentally measured polarization data. Further understanding is developed\nby analyzing the strain fields which suggests that the two-composition model\nindeed results in lower strain energies than the commonly applied uniform\ncomposition model."
    },
    {
        "anchor": "Spontaneous vortex state and $\\varphi$-junction in a superconducting\n  bijunction with a localized spin: A Josephson bijunction made of three superconductors connected by a quantum\ndot is considered in the regime where the dot carries a magnetic moment. In the\nrange of parameters where such a dot, if inserted in a two-terminal Josephson\njunction, creates a $\\pi$-shift of the phase, the bijunction forming a\ntriangular unit is frustrated. This frustration is studied both within a\nphenomenological and a microscopic model. Frustration stabilizes a phase vortex\ncentered on the dot, with two degenerate states carrying opposite vorticities,\nindependently of the direction of the magnetic moment. Embedding the bijunction\nin a superconducting loop allows to create a tunable \"$\\varphi$\"-junction whose\nequilibrium phase can take any value. For large enough inductance, it generates\nnoninteger spontaneous flux. Multi-loop configurations are also studied.",
        "positive": "Signatures of localization in the effective metallic regime of high\n  mobility Si MOSFETs: Combining experimental data, numerical transport calculations, and\ntheoretical analysis, we study the temperature-dependent resistivity of\nhigh-mobility 2D Si MOSFETs to search for signatures of weak localization\ninduced quantum corrections in the effective metallic regime above the critical\ndensity of the so-called two-dimensional metal-insulator transition (2D MIT).\nThe goal is to look for the effect of logarithmic insulating localization\ncorrection to the metallic temperature dependence in the 2D conductivity so as\nto distinguish between the 2D MIT being a true quantum phase transition versus\nbeing a finite-temperature crossover. We use the Boltzmann theory of\nresistivity including the temperature dependent screening effect on charged\nimpurities in the system to fit the data. We analyze weak perpendicluar field\nmagnetoresistance data taken in the vicinity of the transition and show that\nthey are consistent with weak localization behavior in the strongly disordered\nregime $k_F\\ell\\gtrsim1$. Therefore we supplement the Botzmann transport theory\nwith a logarithmic in temperature quantum weak localization correction and\nanalyze the competition of the insulating temperature dependence of this\ncorrection with the metallic temperature dependence of the Boltzmann\nconductivity. Using this minimal theoretical model we find that the logarithmic\ninsulating correction is masked by the metallic temperature dependence of the\nBotzmann resistivity and therefore the insulating $\\log T$ behavior may be\napparent only at very low temperatures which are often beyond the range of\ntemperatures accessible experimentally. Analyzing the low-$T$ experimental Si\nMOSFET transport data we identify signatures of the putative insulating\nbehavior at low temperature and density in the effective metallic phase."
    },
    {
        "anchor": "Finite Conductivity in Mesoscopic Hall Bars of Inverted InAs/GaSb\n  Quantum Wells: We have studied experimentally the low temperature conductivity of mesoscopic\nsize InAs/GaSb quantum well Hall bar devices in the inverted regime. Using a\npair of electrostatic gates we were able to move the Fermi level into the\nelectron-hole hybridization state, and observe a mini gap. Temperature\ndependence of the conductivity in the gap shows residual conductivity, which\ncan be consistently explained by the contributions from the free as well as the\nhybridized carriers in the presence of impurity scattering, as proposed by\nNaveh and Laikhtman [Euro. Phys. Lett., 55, 545-551 (2001)]. Experimental\nimplications for the stability of proposed helical edge states will be\ndiscussed.",
        "positive": "Spin-dependent recombination in GaAs(1-x)N(x) alloys at oblique magnetic\n  field: We have studied experimentally and theoretically the optical orientation and\nspin-dependent Shockley-Read-Hall recombination in a semiconductor in a\nmagnetic field at an arbitrary angle between the field and circularly polarized\nexciting beam. The experiments are performed at room temperature in GaAsN\nalloys where deep paramagnetic centers are responsible for the spin-dependent\nrecombination. The observed magnetic-field dependences of the circular\npolarization r(B) and intensity J(B) of photoluminescence can be approximately\ndescribed as a superposition of two Lorentzian contours, normal and inverted,\nwith their half-widths differing by an order of magnitude. The normal (narrow)\nLorentzian contour is associated with depolarization of the transverse (to the\nfield) component of spin polarization of the localized electrons, whereas the\ninverted (broad) Lorentzian is due to suppression of the hyperfine interaction\nof the localized electron with the defect nucleus. The ratio between the height\nof one Lorentzian and depth of the other is governed by the field tilt angle.\nIn contrast to the hyperfine interaction of a shallow-donor-bound electron with\na large number of nuclei of the crystal lattice, in the optical orientation of\nthe electron-nuclear system under study no additional narrow peak appears in\nthe oblique field. This result demonstrates that in the GaAsN alloys the\nhyperfine interaction of the localized electron with the single nucleus of the\nparamagnetic center remains strong even at room temperature. For a theoretical\ndescription of the experiment, we have extended the theory of spin-dependent\nrecombination via deep paramagnetic centers with the nuclear angular momentum I\n= 1/2 developed previously for the particular case of the longitudinal field.\nThe calculated curves r(B), J(B) agree with the approximate description of the\nexperimental dependences as a sum of two Lorentzians."
    },
    {
        "anchor": "Mechanical analogue of a Majorana bound state: The discovery of topologically non-trivial electronic systems has opened a\nnew age in condensed matter research. From topological insulators to\ntopological superconductors and Weyl semimetals, it is now understood that some\nof the most remarkable and robust phases in electronic systems (e.g., Quantum\nHall or Anomalous Quantum Hall) are the result of topological protection. These\npowerful ideas have recently begun to be explored also in bosonic systems.\nTopologically protected acoustic, mechanical, and optical edge states have been\ndemonstrated in a number of systems that recreate the requisite topological\nconditions. Such states that propagate without backscattering could find\nimportant applications in communications and energy technologies. In this work\nwe demonstrate the mechanical analogue of a topologically bound state, a\ndifferent class of non-propagating protected state that cannot be destroyed by\nlocal perturbations. These are well known in electronic systems, such as\nMajorana bound states in topological superconductors, but remain largely\nunexplored in a bosonic setting. We implement topological binding by creating a\nKekul\\'e distortion vortex on a two-dimensional mechanical honeycomb\nsuperlattice.",
        "positive": "Resonant indirect exchange via remote 2D channel: We apply the previously developed theory of the resonant indirect exchange\ninteraction to explain the ferromagnetic properties of the hybrid\nheterostructure consisting of a InGaAs-based quantum well (QW) sandwiched\nbetween GaAs barriers with a remote Mn delta-layer. The experimentally obtained\ndependence of the Curie temperature on the QW depth exhibits a maximum related\nto the region of resonant indirect exchange. We suggest the theoretical\nexplanantion and a fit to this dependence as a result of the two contributions\nto ferromagnetism - the intralayer contribution and the resonant exchange\ncontribution provided by the QW."
    },
    {
        "anchor": "Transport in Graphene p-n Junctions in Magnetic Field: Ballistic transport in graphene p-n junctions in the presence of magnetic\nfield exhibits two distinct regimes: At low fields, transport is partially\nsuppressed by the field. When the field exceeds a certain critical value, the\njunction is pinched off by the Landau level formation. Transmission and\nconductance are found in the entire range of fields using Lorentz boost and\nmapping to the Landau-Zener problem. We show that perfect transmission occurs\nat a field-dependent collimation angle, indicating that the chiral dynamics of\nmassless Dirac fermions persists at a finite magnetic field. A current switch,\nutilizing field-tunable collimation angle, is proposed. With a generalization\nof the developed approach we study transmission through p-n junctions in\ngraphene bilayer.",
        "positive": "Coulomb bound states and resonances due to groups of Ca dimers adsorbed\n  on suspended graphene: The electronic bound states and resonances in the vicinity of the Dirac point\nenergy due to the adsorption of calcium dimers on a suspended graphene\nmonolayer are explored theoretically using density functional theory (DFT) and\nan improved extended H\\\"uckel model that includes electrostatic potentials. The\nMulliken atomic charges and the electrostatic potentials are obtained from DFT\ncalculations and reveal charge transfer from the Ca dimers to the graphene\nwhich is responsible for the emergence of resonant states in the electronic\nspectrum. The number of resonant states increases as the number of adsorbed\ndimers is increased. We find a bound \"atomic-collapse\" state in the graphene\nlocal density of states, as has been observed experimentally [Wang \\textit{et\nal.}, Science {\\bf 340}, 734 (2013)]. We find the formation of the\natomic-collapse state and its population with electrons to require fewer\nadsorbed Ca dimers than in the experiment, possibly due to the different\nspacing between dimers and the dielectric screening by a boron nitride\nsubstrate in the experiment. We also predict the onset of filling of a second\natomic-collapse state with electrons when six Ca dimers are adsorbed on the\nsuspended graphene monolayer. Experiments testing these predictions would be of\ninterest."
    },
    {
        "anchor": "Non-equilibrium spin polarization effects in spin-orbit coupling system\n  and contacting metallic leads: We study theoretically the current-induced spin polarization effect in a\ntwo-terminal mesoscopic structure which is composed of a semiconductor\ntwo-dimensional electron gas (2DEG) bar with Rashba spin-orbit (SO) interaction\nand two attached ideal leads. The nonequilibrium spin density is calculated by\nsolving the scattering wave functions explicitly within the ballistic transport\nregime. We found that for a Rashba SO system the electrical current can induce\nspin polarization in the SO system as well as in the ideal leads. The induced\npolarization in the 2DEG shows some qualitative features of the intrinsic spin\nHall effect. On the other hand, the nonequilibrium spin density in the ideal\nleads, after being averaged in the transversal direction, is independent of the\ndistance measured from the lead/SO system interface, except in the vicinity of\nthe interface. Such a lead polarization effect can even be enhanced by the\npresence of weak impurity scattering in the SO system and may be detectable in\nreal experiments.",
        "positive": "Quantum Geometric Oscillations in Two-Dimensional Flat-Band Solids: Two-dimensional van der Waals heterostructures can be engineered into\nartificial superlattices that host flat bands with significant Berry curvature\nand provide a favorable environment for the emergence of novel electron\ndynamics. In particular, the Berry curvature can induce an oscillating\ntrajectory of an electron wave packet transverse to an applied static electric\nfield. Though analogous to Bloch oscillations, this novel oscillatory behavior\nis driven entirely by quantum geometry in momentum space instead of band\ndispersion. While the orbits of Bloch oscillations can be localized by\nincreasing field strength, the size of the geometric orbits saturates to a\nnonzero plateau in the strong-field limit. In non-magnetic materials, the\ngeometric oscillations are even under inversion of the applied field, whereas\nthe Bloch oscillations are odd, a property that can be used to distinguish\nthese two co-existing effects."
    },
    {
        "anchor": "Disorder effects in topological insulator nanowires: Three-dimensional topological insulator (TI) nanowires with quantized surface\nsubband spectra are studied as a main component of Majorana bound states (MBS)\ndevices. However, such wires are known to have large concentration $N \\sim\n10^{19}$ cm$^{-3}$ of Coulomb impurities. It is believed that a MBS device can\nfunction only if the amplitude of long-range fluctuations of the random Coulomb\npotential $\\Gamma$ is smaller than the subband gap $\\Delta$. Here we calculate\n$\\Gamma$ for recently experimentally studied large-dielectric-constant\n(Bi$_{1-x}$Sb$_x$)$_2$Te$_{3}$ wires in a small-dielectric-constant environment\n(no superconductor). We show that provided by such a dielectric-constant\ncontrast, the confinement of electric field of impurities within the wire\nallows more distant impurities to contribute into $\\Gamma$, leading to $\\Gamma\n\\sim 3\\Delta$. We also calculate a TI wire resistance as a function of the\nFermi level and carrier concentration due to scattering on Coulomb and neutral\nimpurities, and do not find observable discrete subband-spectrum related\noscillations at $N \\gtrsim 10^{18}$ cm$^{-3}$.",
        "positive": "Braess paradox at the mesoscopic scale: We theoretically demonstrate that the transport inefficiency recently found\nexperimentally for branched-out mesoscopic networks can also be observed in a\nquantum ring of finite width with an attached central horizontal branch. This\nis done by investigating the time evolution of an electron wave packet in such\na system. Our numerical results show that the conductivity of the ring does not\nnecessary improves if one adds an extra channel. This ensures that there exists\na quantum analogue of the Braess Paradox, originating from quantum scattering\nand interference."
    },
    {
        "anchor": "Transient currents of a single molecular junction with a vibrational\n  mode: By using a propagation scheme for current matrices and an auxiliary mode\nexpansion method, we investigate the transient dynamics of a single molecular\njunction coupled with a vibrational mode. Our approach is based on the\nAnderson-Holstein model and the dressed tunneling approximation for the\nelectronic self-energy in the polaronic regime. The time-dependent currents\nafter a sudden switching on the tunneling to leads and an abrupt upward step\nbias pulse are calculated. We show that the strong electron-phonon interaction\ngreatly influences the nonlinear response properties of the system, and gives\nrise to interesting characteristics on the time traces of transient currents.",
        "positive": "Asymmetric nano graphene model applied to graphite-like room-temperature\n  ferromagnetism: Room temperature ferromagnetic materials composed only by light elements like\ncarbon, hydrogen and/or nitrogen, so called carbon magnet, are very attractive\nfor creating new material categories both in science and industry. Recently\nseveral experiments suggest ferromagnetic features at a room temperature,\nespecially in graphite base materials. This paper reveals a mechanism of such\nferromagnetic features by modeling nanometer size asymmetric graphene molecule\nby using both a semi-empirical molecular orbital method and a first principle\ndensity function theory. Asymmetrically dihydrogenated zigzag edge graphene\nmolecule shows that high spin state is more stable in total molecular energy\nthan low spin state. Proton ion irradiation play an important role to create\nsuch asymmetric features. Also, nitrogen contained graphite ferromagnetism is\nexplained by a similar asymmetric molecule model."
    },
    {
        "anchor": "Systematics of electronic and magnetic properties in the transition\n  metal doped Sb$_2$Te$_3$ quantum anomalous Hall platform: The quantum anomalous Hall effect (QAHE) has recently been reported to emerge\nin magnetically-doped topological insulators. Although its general\nphenomenology is well established, the microscopic origin is far from being\nproperly understood and controlled. Here we report on a detailed and systematic\ninvestigation of transition-metal (TM)-doped Sb$_2$Te$_3$. By combining density\nfunctional theory (DFT) calculations with complementary experimental\ntechniques, i.e., scanning tunneling microscopy (STM), resonant photoemission\n(resPES), and x-ray magnetic circular dichroism (XMCD), we provide a complete\nspectroscopic characterization of both electronic and magnetic properties. Our\nresults reveal that the TM dopants not only affect the magnetic state of the\nhost material, but also significantly alter the electronic structure by\ngenerating impurity-derived energy bands. Our findings demonstrate the\nexistence of a delicate interplay between electronic and magnetic properties in\nTM-doped TIs. In particular, we find that the fate of the topological surface\nstates critically depends on the specific character of the TM impurity: while\nV- and Fe-doped Sb$_2$Te$_3$ display resonant impurity states in the vicinity\nof the Dirac point, Cr and Mn impurities leave the energy gap unaffected. The\nsingle-ion magnetic anisotropy energy and easy axis, which control the magnetic\ngap opening and its stability, are also found to be strongly TM\nimpurity-dependent and can vary from in-plane to out-of-plane depending on the\nimpurity and its distance from the surface. Overall, our results provide\ngeneral guidelines for the realization of a robust QAHE in TM-doped\nSb$_2$Te$_3$ in the ferromagnetic state.",
        "positive": "Nonuniversality of the intrinsic inverse spin-Hall effect in diffusive\n  systems: We studied the electric current induced in a two-dimensional electron gas by\nthe spin current, in the presence of Rashba and cubic Dresselhaus spin-orbit\ninteractions. We found out that the factor relating these currents is not\nuniversal, but rather depends on the origin of the spin current. Drastic\ndistinction has been found between two cases: the spin current created by\ndiffusion of an inhomogeneous spin density, and the pure homogeneous spin\ncurrent. We found out that in the former case the ISHE electric current is\nfinite, while it turns to zero in the latter case, if the spin-orbit coupling\nis represented by Rashba interaction."
    },
    {
        "anchor": "Strong coupling of an Er3+ doped YAlO3 crystal to a superconducting\n  resonator: Quantum memories are integral parts of both quantum computers and quantum\ncommunication networks. Naturally, such a memory is embedded into a hybrid\nquantum architecture, which has to meet the requirements of fast gates, long\ncoherence times and long distance communication. Erbium doped crystals are well\nsuited as a microwave quantum memory for superconducting circuits with\nadditional access to the optical telecom C-band around 1.55 {\\mu}m. Here, we\nreport on circuit QED experiments with an Er3+:YAlO3 crystal and demonstrate\nstrong coupling to a superconducting lumped element resonator. The low magnetic\nanisotropy of the host crystal allows for attaining the strong coupling regime\nat relatively low magnetic fields, which are compatible with superconducting\ncircuits. In addition, Ce3+ impurities were detected in the crystal, which\nshowed strong coupling as well.",
        "positive": "Voltage Induced Switching of Nanomagnets in Topological Insulator\n  Magnetoelectric Devices through Ruderman-Kittel-Kasuya-Yosida Interactions: In this letter, we demonstrate switching of nanomagnets through RKKY\ninteractions in topological insulator-based magnetoelectric devices. The\nswitching speed is dependent on the size of the ferromagnets."
    },
    {
        "anchor": "Magnetoplasma excitations of two vertically coupled dots: A classical hydrodynamic approach is used to calculate the magnetoplasma\nexcitations of two vertically coupled electron dots. The electrons are confined\nby different parabolic potentials in which case Kohn's theorem is no longer\nvalid. The equilibrium density profiles of the electrons in both dots are\ncalculated as function of the interdot distance. We find that for unequal\nconfinements of the two dots the electron density in one of the dots becomes\nring-like. The electron densities are then used to obtain the magnetoplasma\nfrequencies. The oscillator strengths are calculated, and we find that other\nthen the center of mass modes can be excited due to the electron-electron\ninteractions.",
        "positive": "Time-reversal odd transport in bilayer graphene: Hall conductivity and\n  Hall viscosity: We consider the time-reversal odd dynamics of the bilayer graphene at low\nenergies in the quantum Hall regime. A generating functional for the effective\naction that captures the electromagnetic response to all orders in momentum and\nfrequency is presented and evaluated to the third order in the space-time\ngradient $\\mathcal O(\\partial^3)$. In addition, we calculate the Hall viscosity\nand derive an explicit relationship with the $q^2$ coefficient of the Hall\nconductivity. It is reminiscent of the Hoyos--Son relation in the Galilean\ninvariant systems, which can be recovered in the limit of large filling factor\n$N$."
    },
    {
        "anchor": "Magnetic-field-induced dimensional crossover in the organic metal\n  $\u03b1$-(BEDT-TTF)$_{2}$KHg(SCN)$_{4}$: The field dependence of interlayer magnetoresistance of the pressurized (to\nthe normal state) layered organic metal $\\alpha\n$-(BEDT-TTF)$_{2}$KHg(SCN)$_{4}$ is investigated. The high\nquasi-two-dimensional anisotropy, when the interlayer hopping time is longer\nthan the electron mean-free time and than the cyclotron period, leads to a\ndimensional crossover and to strong violations of the conventional\nthree-dimensional theory of magnetoresistance. The monotonic field dependence\nis found to change from the conventional behavior at low magnetic fields to an\nanomalous one at high fields. The shape of Landau levels, determined from the\ndamping of magnetic quantum oscillations, changes from Lorentzian to Gaussian.\nThis indicates the change of electron dynamics in the disorder potential from\nthe usual coherent three-dimensional regime to a new regime, which can be\nreferred to as weakly coherent.",
        "positive": "Topological aspects of nonlinear excitonic processes in\n  noncentrosymmetric crystals: We study excitonic processes second order in the electric fields in\nnoncentrosymmetric crystals. We derive formulas for shift current and second\nharmonic generation produced by exciton creation, by using the Floquet\nformalism combined with the Keldysh Green's function method. It is shown that\n(i) the steady dc shift current flows by exciton creation without dissociation\ninto free carriers and (ii) second harmonic generation is enhanced at the\nexciton resonance. The obtained formulas clarify topological aspects of these\nsecond order excitonic processes which are described by Berry connections of\nthe relevant valence and conduction bands."
    },
    {
        "anchor": "Aharonov-Bohm interference in quantum ring exciton: effects of built-in\n  electric fields: We report a comprehensive discussion of quantum interference effects due to\nthe finite structure of excitons in quantum rings and their first experimental\ncorroboration observed in the optical recombinations. Anomalous features that\nappear in the experiments are analyzed according to theoretical models that\ndescribe the modulation of the interference pattern by temperature and built-in\nelectric fields.",
        "positive": "Two-Dimensional Wide-Band-Gap II-V Semiconductors with a Dilated\n  Graphene-like Structure: Since the advent of graphene, two-dimensional (2D) materials become very\nattractive and there is growing interest to explore new 2D beyond graphene.\nHere, through density functional theory (DFT) calculations, we predict 2D\nwide-band-gap II-V semiconductor materials of M$_3$X$_2$ (M=Zn, Cd and X=N, P,\nAs) with a dilated graphene-like honeycomb structure. The structure features\nthat the group-V X atoms form two X-atomic planes symmetrically astride the\ncentering group-IIB M atomic plane. The 2D Zn$_3$N$_2$, Zn$_3$P$_2$, and\nZn$_3$As$_2$ are shown to have direct band gaps of 2.87, 3.81, and 3.55 eV,\nrespectively, and the 2D Cd$_3$N$_2$, Cd$_3$P$_2$, and Cd$_3$As$_2$ exhibit\nindirect band gaps of 2.74, 3.51, and 3.29 eV, respectively. Each of the six 2D\nmaterials is shown to have effective carrier (either hole or electron) masses\ndown to $0.03\\sim 0.05$ $m_0$. The structural stability and feasibility of\nexperimental realization of these 2D materials has been shown in terms of DFT\nphonon spectra and total energy comparison with related existing bulk\nmaterials. On the experimental side, there already are many similar\ntwo-coordinate structures of Zn and other transition metals in various organic\nmaterials, which can be considered to support our DFT prediction. Therefore,\nthese 2D semiconductors can enrich the family of 2D electronic materials and\nmay have promising potential for achieving novel transistors and optoelectronic\ndevices."
    },
    {
        "anchor": "Magneto-mechanical interplay in spin-polarized point contacts: We investigate the interplay between magnetic and structural dynamics in\nferromagnetic atomic point contacts. In particular, we look at the effect of\nthe atomic relaxation on the energy barrier for magnetic domain wall migration\nand, reversely, at the effect of the magnetic state on the mechanical forces\nand structural relaxation. We observe changes of the barrier height due to the\natomic relaxation up to 200%, suggesting a very strong coupling between the\nstructural and the magnetic degrees of freedom. The reverse interplay is weak,\ni.e. the magnetic state has little effect on the structural relaxation at\nequilibrium or under non-equilibrium, current-carrying conditions.",
        "positive": "Nonlocal magnon-polaron transport in yttrium iron garnet: The spin Seebeck effect (SSE) is observed in magnetic insulator|heavy metal\nbilayers as an inverse spin Hall effect voltage under a temperature gradient.\nThe SSE can be detected nonlocally as well, viz. in terms of the voltage in a\nsecond metallic contact (detector) on the magnetic film, spatially separated\nfrom the first contact that is used to apply the temperature bias (injector).\nMagnon-polarons are hybridized lattice and spin waves in magnetic materials,\ngenerated by the magnetoelastic interaction. Kikkawa et al. [Phys. Rev. Lett.\n\\textbf{117}, 207203 (2016)] interpreted a resonant enhancement of the local\nSSE in yttrium iron garnet (YIG) as a function of the magnetic field in terms\nof magnon-polaron formation. Here we report the observation of magnon-polarons\nin \\emph{nonlocal} magnon spin injection/detection devices for various\ninjector-detector spacings and sample temperatures. Unexpectedly, we find that\nthe magnon-polaron resonances can suppress rather than enhance the nonlocal\nSSE. Using finite element modelling we explain our observations as a\ncompetition between the SSE and spin diffusion in YIG. These results give\nunprecedented insights into the magnon-phonon interaction in a key magnetic\nmaterial."
    },
    {
        "anchor": "Electromechanical feedback control of nanoscale superflow: Superfluid $^4$He is a promising material for optomechanical and\nelectromechanical applications due to its low acoustic loss. Some of the more\nintriguing aspects of superfluidity -- the macroscopic coherence, topological\nnature of vorticity, and capability of supporting non-classical flows --\nremain, however, poorly explored resources in opto- and electro-mechanical\nsystems. Here, we present an electromechanical coupling to pure superflow\ninside a nanofluidic Helmholtz resonator with viscously clamped normal fluid.\nThe system is capable of simultaneous measurement of displacement and velocity\nof the Helmholtz mechanical mode weakly driven by incoherent environmental\nnoise. Additionally, we implement feedback capable of inducing self-oscillation\nof the non-classical acoustic mode, damping the motion below the ambient level,\nand tuning of the mode frequency.",
        "positive": "Aharonov-Bohm oscillations of a tunable quantum ring: With an atomic force microscope a ring geometry with self-aligned in-plane\ngates was directly written into a GaAs/AlGaAs-heterostructure. Transport\nmeasurements in the open regime show only one transmitting mode and\nAharonov-Bohm oscillations with more than 50% modulation are observed in the\nconductance. The tuning via in-plane gates allows to study the Aharonov-Bohm\neffect in the whole range from the open ring to the Coulomb-blockade regime."
    },
    {
        "anchor": "Current fluctuations in composite conductors: Beyond the second cumulant: Employing the non-linear $\\sigma$-model we analyze current fluctuations in\ncoherent composite conductors which contain a diffusive element in-between two\ntunnel barriers. For such systems we explicitly evaluate the\nfrequency-dependent third current cumulant which also determines the leading\nCoulomb interaction correction to shot noise. Our predictions can be directly\ntested in future experiments.",
        "positive": "On the emergence of heat waves in the transient thermal grating geometry: The propagation of heat in the transient thermal grating geometry is studied\nbased on phonon Boltzmann transport equation (BTE) in different phonon\ntransport regimes. Our analytical and numerical results show that the phonon\ndispersion relation and temperature play a significant role in the emergence of\nheat wave. For the frequency-independent BTE, the heat wave appears as long as\nthe phonon resistive scattering is not sufficient, while for the\nfrequency-dependent BTE, the heat wave could disappear in the ballistic regime,\ndepending on the grating period and temperature. We predict that the heat wave\ncould appear in the suspended graphene and silicon in extremely low temperature\nbut disappear at room temperature."
    },
    {
        "anchor": "Thermoelectric effect enhanced by the resonant states in graphene: Thermoelectric effects in graphene are considered theoretically with\nparticular attention paid to the role of impurities. Using the T -matrix method\nwe calculate the impurity resonant states and the momentum relaxation time due\nto scattering on impurities. The Boltzmann kinetic equation is used to\ndetermine the thermoelectric coefficients. It is shown that the resonant\nimpurity states near the Fermi level give rise to a resonant enhancement of the\nSeebeck coefficient and of the figure of merit $ZT$ . The Wiedemann-Franz ratio\ndeviates from that known for ordinary metals, where this ratio is constant and\nequal to the Lorentz number. This deviation appears for small chemical\npotentials and in the vicinity of the resonant states. In the limit of a\nconstant relaxation time, this ratio has been calculated analytically for\n$\\mu=0$.",
        "positive": "Thermal and Tunneling Pair Creation of Quasiparticles in Quantum Hall\n  Systems: We make a semiclassical analysis of thermal pair creations of quasiparticles\nat various filling factors in quantum Hall systems. It is argued that the gap\nenergy is reduced considerably by the Coulomb potential made by impurities. It\nis also shown that a tunneling process becomes important at low temperature and\nat strong magnetic field. We fit typical experimental data excellently based on\nour semiclassical results of the gap energy."
    },
    {
        "anchor": "Local and Non-local Shot Noise in Multiwalled Carbon Nanotubes: We have investigated shot noise in multiterminal, diffusive multiwalled\ncarbon nanotubes (MWNTs) at 4.2 K over the frequency f = 600 - 850 MHz.\nQuantitative comparison of our data to semiclassical theory, based on\nnon-equilibrium distribution functions, indicates that a major part of the\nnoise is caused by a non-equilibrium state imposed by the contacts. Our data\nexhibits non-local shot noise across weakly transmitting contacts while a\nlow-impedance contact eliminates such noise almost fully. We obtain F_{tube}<\n0.03 for the intrinsic Fano factor of our MWNTs.",
        "positive": "Magnetostatic bias in multilayer microwires: theory and experiments: The hysteresis curves of multilayer microwires consisting of a soft magnetic\nnucleus, intermediate non-magnetic layers, and an external hard magnetic layer\nare investigated. The magnetostatic interaction between magnetic layers is\nproved to give rise to an antiferromagnetic-like coupling resulting in a\nmagnetostatic bias in the hysteresis curves of the soft nucleus. This\nmagnetostatic biasing effect is investigated in terms of the microwire\ngeometry. The experimental results are interpreted considering an analytical\nmodel taking into account the magnetostatic interaction between the magnetic\nlayers."
    },
    {
        "anchor": "Optical Probing of Electronic Interaction between Graphene and Hexagonal\n  Boron Nitride: Even weak van der Waals (vdW) adhesion between two-dimensional solids may\nperturb their various materials properties owing to their low dimensionality.\nAlthough the electronic structure of graphene has been predicted to be modified\nby the vdW interaction with other materials, its optical characterization has\nnot been successful. In this report, we demonstrate that Raman spectroscopy can\nbe utilized to detect a few % decrease in the Fermi velocity (vF) of graphene\ncaused by the vdW interaction with underlying hexagonal boron nitride (hBN).\nOur study also establishes Raman spectroscopic analysis which enables\nseparation of the effects by the vdW interaction from those by mechanical\nstrain or extra charge carriers. The analysis reveals that spectral features of\ngraphene on hBN are mainly affected by change in vF and mechanical strain, but\nnot by charge doping unlike graphene supported on SiO2 substrates. Graphene on\nhBN was also found to be less susceptible to thermally induced hole doping.",
        "positive": "Confined states and topological phases in two-dimensional\n  quasicrystalline $\u03c0$-flux model: Motivated by topological equivalence between an extended Haldane model and a\nchiral-$\\pi$-flux model on a square lattice, we apply $\\pi$-flux models to\ntwo-dimensional bipartite quasicrystals with rhombus tiles in order to\ninvestigate topological properties in aperiodic systems. Topologically trivial\n$\\pi$-flux models in the Ammann-Beenker tiling lead to massively degenerate\nconfined states whose energies and fractions differ from the zero-flux model.\nThis is different from the $\\pi$-flux models in the Penrose tiling, where\nconfined states only appear at the center of the bands as is the case of a\nzero-flux model. Additionally, Dirac cones appear in a certain $\\pi$-flux model\nof the Ammann-Beenker approximant, which remains even if the size of the\napproximant increases. Nontrivial topological states with nonzero Bott index\nare found when staggered tile-dependent hoppings are introduced in the\n$\\pi$-flux models. This finding suggests a new direction in realizing\nnontrivial topological states without a uniform magnetic field in aperiodic\nsystems."
    },
    {
        "anchor": "Disorder-induced nonlinear Hall effect with time-reversal symmetry: The nonlinear Hall effect has opened the door towards deeper understanding of\ntopological states of matter. It can be observed as the double-frequency Hall\nvoltage response to an ac longitudinal current in the presence of time-reversal\nsymmetry. Disorder plays indispensable roles in various linear Hall effects,\nsuch as the localization in the quantized Hall effects and the extrinsic\nmechanisms of the anomalous, spin, and valley Hall effects. Unlike in the\nlinear Hall effects, disorder enters the nonlinear Hall effect even in the\nleading order. However, the disorder-induced contribution to the nonlinear Hall\neffect has not been addressed. Here, we derive the formulas of the nonlinear\nHall conductivity in the presence of disorder scattering. We apply the formulas\nto calculate the nonlinear Hall response of the tilted 2D Dirac model, which is\nthe symmetry-allowed minimal model for the nonlinear Hall effect and can serve\nas a building block in realistic band structures. More importantly, we\nconstruct the general scaling law of the nonlinear Hall effect, which may help\nin experiments to distinguish disorder-induced contributions to the nonlinear\nHall effect. This work will be instructive for exploring unconventional\nresponses upon breaking discrete or crystal symmetries in emergent physical\nsystems and materials.",
        "positive": "Prediction of confined and controllable Bloch points in nanocubes of\n  chiral magnets: This work predicts that individual Bloch points can be created and stabilized\nby magnetostatic and chiral interactions in nanocuboids, confined in between\ntwo chiral bobbers of opposing polarity. The Bloch point can be moved by an\nexternal magnetic field of moderate strength but only if the field strength is\nenough to overcome a pinning potential that results from intrinsic exchange\nforces and extrinsic surface effects. The Bloch point can be driven by the\nexternal field reversibly, in a direction opposing the field, and it remains\nstable up to moderate field strengths. At a critical field strength the Bloch\npoint escapes through one of the surfaces, leaving behind a collinear\nmagnetization configuration, and upon removing the field a new Bloch point is\nformed. These findings highlight the topological diversity in nanostructures\nand show that a Bloch point, despite its zero-dimensionality, couples to\nexternal fields via a substantial magnetic volume around it. The control of\ntopological point defects has technological implications with regards to\nreversibly movable nanomagnetic textures and their associated emergent\nelectrodynamics."
    },
    {
        "anchor": "Entanglement renormalization for chiral topological phases: We considered the question of applying the multiscale entanglement\nrenormalization ansatz (MERA) to describe chiral topological phases. We defined\na functional for each layer in the MERA, which captures the correlation length.\nWith some algebraic geometry tools, we rigorously proved its monotonicity with\nrespect to adjacent layers, and the existence of a lower bound for chiral\nstates, which shows a trade-off between the bond dimension and the correlation\nlength. Using this theorem, we showed the number of orbitals per cell (which\nroughly corresponds to the bond dimension) should grow with the height.\nConversely, if we restrict the bond dimensions to be constant, then there is an\nupper bound of the height. Specifically, we established a no-go theorem stating\nthat we will not approach a renormalization fixed point in this case.",
        "positive": "Plateau insulator transition in graphene: The quantum Hall effect in a single-layer graphene sample is studied in\nstrong magnetic fields up to 28 T. Our measurements reveal the existence of a\nmetal- insulator transition from filling factor $\\nu=-2$ to $\\nu=0$. The value\nof the universal scaling exponent is found to be $\\kappa=0.57 $ in graphene and\ntherefore in a truly two-dimensional system. This value of $\\kappa$ is in\nagreement with the accepted universal value for the plateau-insulator\ntransitions in standard quasi two-dimensional electron and hole gases."
    },
    {
        "anchor": "Difference frequency generation in topological semimetals: When two lasers are applied to a non-centrosymmetric material, light can be\ngenerated at the difference of the incoming frequencies $\\Delta\\omega$, a\nphenomenon known as difference frequency generation (DFG), well characterized\nin semiconductors. In this work, we derive a general expression for DFG in\nmetals, which we use to show that the DFG in chiral topological semimetals\nunder circular polarized light is quantized in units of $e^3/h^2$ and\nindependent of material parameters, including the scattering time $\\tau$, when\n$\\Delta\\omega \\gg \\tau^{-1}$. In this regime, DFG provides a simpler\nalternative to measure a quantized response in metals compared to previous\nproposals based on single frequency experiments. Our general derivation\nunmasks, in addition, a free-carrier contribution to the circular DFG beyond\nthe semiclassical one. This contribution can be written as a Fermi surface\nintegral, features strong frequency dependence, and oscillates with a $\\pi/2$\nshift with respect to the quantized contribution. We make predictions for the\ncircular DFG of chiral and non-chiral materials using generic effective models,\nand ab-initio calculations for TaAs and RhSi. Our work provides a complete\npicture of the DFG in the length gauge approach, in the clean, non-interacting\nlimit, and highlights a plausible experiment to measure topologically\nquantizated photocurrents in metals.",
        "positive": "Crystalline topological states at a topological insulator junction: We consider an interface between two strong time-reversal invariant\ntopological insulators having surface states with opposite spin chirality, or\nequivalently, opposite mirror Chern number. We show that such an interface\nsupports gapless modes that are protected by mirror symmetry. The interface\nstates are investigated with a continuum model for the Bi2Se3 class of\ntopological insulators that takes into account terms up to third order in the\ncrystal momentum, which ensures that the model has the correct symmetry. The\nmodel parameters are obtained from ab initio calculations. Finally, we consider\nthe effect of rotational mismatch at the interface, which breaks the mirror\nsymmetry and opens a gap in the interface spectrum."
    },
    {
        "anchor": "Transport and drag in undoped electron-hole bilayers: We investigate transport and Coulomb drag properties of semiconductor-based\nelectron-hole bilayer systems. Our calculations are motivated by recent\nexperiments in undoped electron-hole bilayer structures based on GaAs-AlGaAs\ngated double quantum well systems. Our results indicate that the background\ncharged impurity scattering is the most dominant resistive scattering mechanism\nin the high-mobility bilyers. We also find that the drag transresistivity is\nsignificantly enhanced when the electron-hole layer separation is small due to\nthe exchange induced renormalization of the single layer compressibility.",
        "positive": "Hierarchy of Electronic Properties of Chemically Derived and Pristine\n  Graphene Probed by Microwave Imaging: Local electrical imaging using microwave impedance microscope is performed on\ngraphene in different modalities, yielding a rich hierarchy of the local\nconductivity. The low-conductivity graphite oxide and its derivatives show\nsignificant electronic inhomogeneity. For the conductive chemical graphene, the\nresidual defects lead to a systematic reduction of the microwave signals. In\ncontrast, the signals on pristine graphene agree well with a lumped-element\ncircuit model. The local impedance information can also be used to verify the\nelectrical contact between overlapped graphene pieces."
    },
    {
        "anchor": "Non-stationary effects in the system of coupled quantum dots influenced\n  by the Coulomb correlations: We found analytical solution for the time evolution of localized electron\ndensity in a system of two coupled single-level quantum dots (QDs) connected\nwith continuous spectrum states in the presence of Coulomb interaction. This\nsolution takes into account QD electrons correlation functions of all orders\nneglecting any correlations between localized and conduction electron filling\nnumbers.\n  We demonstrated that several time scales with the strongly different\nrelaxation rates appear in the system for a wide range of the Coulomb\ninteraction value. We revealed that specific non monotonic behavior of charge\nrelaxation in QD takes place due to Coulomb correlations.\n  We also found out that besides the usual charge oscillations with the period\ndetermined by the detuning between the energy levels of the QDs a new effect of\nperiod doubling appears in the presence of Coulomb interaction at particular\nrange of the system parameters.",
        "positive": "Simultaneous quantization of edge and bulk Hall conductivity: The edge Hall conductivity is shown to be an integer multiple of $e^2/h$\nwhich is almost surely independent of the choice of the disordered\nconfiguration. Its equality to the bulk Hall conductivity given by the\nKubo-Chern formula follows from K-theoretic arguments. This leads to\nquantization of the Hall conductance for any redistribution of the current in\nthe sample. It is argued that in experiments at most a few percent of the total\ncurrent can be carried by edge states."
    },
    {
        "anchor": "Surface superconductivity in a three-dimensional Cd$_3$As$_2$ semimetal: We experimentally investigate charge transport through a single planar\njunction between Cd$_3$As$_2$ Dirac semimetal and a normal Au lead. For\nnon-superconducting bulk Cd$_3$As$_2$ samples, we observe non-Ohmic $dV/dI(V)$\ncurves, which strongly resemble standard Andreev reflection with well-defined\nsuperconducting gap. Andreev-like behavior is demonstrated for Cd$_3$As$_2$\nsamples with different surface and contact preparation techniques. We connect\nthis behavior with surface superconductivity due to the flat-band formation in\nCd$_3$As$_2$, which has been predicted theoretically. The conclusion on\nsuperconductivity is also supported by the gap suppression by magnetic fields\nor temperature.",
        "positive": "Anisotropic 2D materials for tunable hyperbolic plasmonics: Motivated by the recent emergence of a new class of anisotropic 2D materials,\nwe examine their electromagnetic modes and demonstrate that a broad class of\nthe materials can host highly directional hyperbolic plasmons. Their\npropagation direction can be manipulated on-the-spot by gate doping, enabling\nhyperbolic beams reflection, refraction and bending. The realization of these\nnatural 2D hyperbolic media opens up a new avenue in dynamic control of\nhyperbolic plasmons not possible in the 3D version."
    },
    {
        "anchor": "Magnetic Order in 3D Topological Insulators -- Wishful Thinking or\n  Gateway to Emergent Quantum Effects?: Three-dimensional topological insulators (TIs) are a perfectly tuned\nquantum-mechanical machinery in which counter-propagating and oppositely\nspin-polarized conduction channels balance each other on the surface of the\nmaterial. This topological surface state crosses the bandgap of the TI, and\nlives at the interface between the topological and a trivial material, such as\nvacuum. Despite its balanced perfection, it is rather useless for any practical\napplications. Instead, it takes the breaking of time-reversal symmetry (TRS),\nand the appearance of an exchange gap to unlock hidden quantum states. The\nquantum anomalous Hall effect, which has first been observed in Cr-doped\n(Sb,Bi)$_2$Te$_3$, is an example of such a state in which two edge channels are\nformed at zero field, crossing the magnetic exchange gap. The breaking of TRS\ncan be achieved by magnetic doping of the TI with transition metal or rare\nearth ions, modulation doping to keep the electronically active channel\nimpurity free, or by proximity coupling to a magnetically ordered layer or\nsubstrate, in heterostructures or superlattices. We review the challenges these\napproaches are facing in the famous 3D TI (Sb,Bi)$_2$(Se,Te)$_3$ family, and\ntry to answer the question whether these materials can live up to the hype\nsurrounding them.",
        "positive": "Boron Nitride Nanosheets Improve Sensitivity and Reusability of Surface\n  Enhanced Raman Spectroscopy: Surface enhanced Raman spectroscopy (SERS) is a useful multidisciplinary\nanalytic technique. However, it is still a challenge to produce SERS substrates\nthat are highly sensitive, reproducible, stable, reusable, and scalable. Here,\nwe demonstrate that atomically thin boron nitride (BN) nanosheets have many\nunique and desirable properties to help solve this challenge. The synergic\neffect of the atomic thickness, high flexibility, stronger surface adsorption\ncapability, electrical insulation, impermeability, high thermal and chemical\nstability of BN nanosheets can increase the Raman sensitivity by up to two\norders, and in the meantime attain long-term stability and extraordinary\nreusability not achievable by other materials. These advances will greatly\nfacilitate the wider use of SERS in many fields."
    },
    {
        "anchor": "Dynamical polarizability, screening, and plasmons in one, two, and three\n  dimensional massive Dirac systems: We study the density-density response function of a collection of charged\nmassive Dirac particles and present analytical expressions for the dynamical\npolarization function in one, two and three dimensions. The polarization\nfunction is then used to find the dispersion of the plasmon modes, and\nelectrostatic screening of Coulomb interactions within the random phase\napproximation. We find that for massive Dirac systems, the oscillating screened\npotential decays as $r^{-1}$, $r^{-2}$ and $r^{-3}$ in one, two, and three\ndimensions respectively. However for massless Dirac systems there is no\nelectrostatic screening or Friedel oscillation in one dimension, and the\noscillating screened potential decays as $r^{-3}$ and $r^{-4}$, in two and\nthree dimensions respectively. Our analytical results for the polarization\nfunction will be useful for exploring the physics of massive and massless Dirac\nmaterials in different experimental systems with varying dimensionality.",
        "positive": "Dirac spectrum in gated multilayer black phosphorus nanoribbons: We investigate the effects of a perpendicular electric field applied to\nmultilayer phosphorene nanoribbons with zigzag and armchair edges. Within the\ncontext of the tight-binding model, we explore the electronic properties of\nthese systems giving emphasis to the appearance of Dirac-like spectra, a\ntransition that occurs when the gate density associated with the applied\ndisplacement field is greater than the critical value $n_c$. We show that the\nconfinement properties and the screening effects in such systems play an\nimportant role on the determination of $n_c$, suggesting a scheme to determine\nthe thickness, width and edge orientation of multilayered phosphorene\nnanoribbons. We also explore how this transition affects the electronic\ntransport properties of such systems."
    },
    {
        "anchor": "Nodal Brillouin Zone Boundary from Folding a Chern Insulator: Chern insulator is a building block of many topological quantum matters,\nranging from quantum spin Hall insulators to fractional Chern insulators. Here,\nwe discuss a new type of insulator, which consists of two half filled ordinary\nChern insulators. On the one hand, the bulk energy spectrum is obtained from\nfolding that of either Chern insulator. Such folding gives rise to a nodal\nboundary of the Brillouin zone, at which the band crossing is protected by the\nsymmetries of the two-dimensional lattice that is invariant under combined\ntransformations in the spatial and the spin space. It also provides one a\nnatural platform to explore the non-abelian Berry curvature and the resultant\nquantum phenomena. On the other hand, these two underlying Chern insulators are\ndistinguished from each other by nonsymmorphic operators, which lead to\nintriguing properties absent in conventional Chern insulators. A new degree of\nfreedom, the parity of the nonsymmorphic symmetry, needs to be introduced for\ndescribing the topological pumping, if the edge respects the nonsymmorphic\nsymmetry.",
        "positive": "Generalized Quantum Geometric Tensor in a Non-Hermitian\n  Exciton-Polariton System: In this work, we review different generalizations of the quantum geometric\ntensor (QGT) in two-band non-Hermitian systems and propose a protocol for\nmeasuring them in experiments. We present the generalized QGT components, i.e.\nthe quantum metric and Berry curvature, for a non-Hermitian hybrid photonic\n(exciton-polariton) system and show that the generalized non-Hermitian QGT can\nbe constructed from experimental observables. In particular, we extend the\nexisting method of measuring the QGT that uses the pseudospins in photonic and\nexciton-polariton systems by suggesting a method to construct the left\neigenstates from experiments. We also show that the QGT components have clear\nsignatures in wave-packet dynamics, where the anomalous Hall drift arises from\nboth the non-Hermitian Berry curvature and Berry connection, suggesting that\nboth left and right eigenstates are necessary for defining non-Hermitian band\ngeometries and topologies."
    },
    {
        "anchor": "Enhanced skyrmion motion via strip domain wall: When magnetic skyrmions move under spin orbit torque in magnetic nanowires,\nthey experience a skyrmion Hall effect, which pushes them towards the nanowire\nedge where they risk being annihilated; this puts an upper limit on how fast\nthey can be driven. However, the same magnetic multilayer harboring skyrmions\ncan sustain a N\\'eel-type strip domain wall along the nanowire length,\npotentially keeping the skyrmions separated from the edge. Here we study the\ninterplay between current driven skyrmions and domain walls and find that they\nincrease the annihilation current and allow the skyrmions to move faster. Based\non the Thiele formalism, we confirm that the emergent longitudinal repulsive\nforce and the modified energy landscape linked to the domain wall are\nresponsible for the enhanced skyrmion motion. Furthermore, we identify that the\nlongitudinal repulsive force emerges because of the broken axisymmetry in the\nlocal magnetization in front of the skyrmion. Our study uncovers key aspects in\nthe interplay between two topological magnetic textures from different homotopy\ngroups and may inspire new device concepts.",
        "positive": "Optical transitions, exciton radiative decay, and valley coherence in\n  lead chalcogenide quantum dots: We propose the concept of valley coherence and superradiance in the\nreciprocal space and show that it leads to an $N$-fold decrease of the bright\nexciton radiative lifetime in quantum dots (QDs) of an $N$-valley\nsemiconductor. Next we explain why, despite this, the exciton radiative\nlifetimes in PbX (X = S, Se, Te) QDs, measured from the photoluminescence\ndecay, are in the microsecond range. We also address peculiarities of the\nlight-matter interaction in nanostructures made of narrow-gap materials with\nstrong inter-band coupling."
    },
    {
        "anchor": "The $k\\cdot p$ model: a short overview for beginners: Lecture-notes: introducing and discussing basic kp concepts related to bands\ninteraction at an elementary level to beginners",
        "positive": "Two-parameter scaling theory of transport near a spectral node: We investigate the finite-size scaling behavior of the conductivity in a\ntwo-dimensional Dirac electron gas within a chiral sigma model. Based on the\nfact that the conductivity is a function of system size times scattering rate,\nwe obtain a two-parameter scaling flow toward a finite fixed point. The latter\nis the minimal conductivity of the infinite system. Depending on boundary\nconditions, we also observe unstable fixed points with conductivities much\nlarger than the experimentally observed values, which may account for results\nfound in some numerical simulations. By including a spectral gap we extend our\nscaling approach to describe a metal-insulator transition."
    },
    {
        "anchor": "Quantum spin Hall effect in rutile-based oxide multilayers: Dirac points in two-dimensional electronic structures are a source for\ntopological electronic states due to the $\\pm \\pi$ Berry phase that they\nsustain. Here we show that two rutile multilayers (namely\n(WO$_2$)$_2$/(ZrO$_2$)$_n$ and (PtO$_2$)$_2$/(ZrO$_2$)$_n$, where an active\nbilayer is sandwiched by a thick enough (n=6 is sufficient) band insulating\nsubstrate, show semi-metallic Dirac dispersions with a total of four Dirac\ncones along the $\\Gamma-M$ direction. These become gapped upon the introduction\nof spin-orbit coupling, giving rise to an insulating ground state comprising\nfour edge states. We discuss the origin of the lack of topological protection\nin terms of the valley spin-Chern numbers and the multiplicity of Dirac points.\nWe show with a model Hamiltonian that mirror-symmetry breaking would be capable\nof creating a quantum phase transition to a strong topological insulator, with\na single Kramers pair per edge.",
        "positive": "Knot topology of exceptional point and non-Hermitian no-go theorem: Exceptional points (EPs) are peculiar band singularities and play a vital\nrole in a rich array of unusual optical phenomena and non-Hermitian band\ntheory. In this paper, we provide a topological classification of isolated EPs\nbased on homotopy theory. In particular, the classification indicates that an\n$n$-th order EP in two dimensions is fully characterized by the braid group\nB$_n$, with its eigenenergies tied up into a geometric knot along a closed path\nenclosing the EP. The quantized discriminant invariant of the EP is the writhe\nof the knot. The knot crossing number gives the number of bulk Fermi arcs\nemanating from each EP. Furthermore, we put forward a non-Hermitian no-go\ntheorem, which governs the possible configurations of EPs and their splitting\nrules on a two-dimensional lattice and goes beyond the previous fermion\ndoubling theorem. We present a simple algorithm generating the non-Hermitian\nHamiltonian with a prescribed knot. Our framework constitutes a systematic\ntopological classification of the EPs and paves the way towards exploring the\nintriguing phenomena related to the enigmatic non-Hermitian band degeneracy."
    },
    {
        "anchor": "Ergodic vs diffusive decoherence in mesoscopic devices: We report on the measurement of phase coherence length in a high mobility\ntwo-dimensional electron gas patterned in two different geometries, a wire and\na ring. The phase coherence length is extracted both from the weak localization\ncorrection in long wires and from the amplitude of the Aharonov-Bohm\noscillations in a single ring, in a low temperature regime when decoherence is\ndominated by electronic interactions. We show that these two measurements lead\nto different phase coherence lengths, namely $L_{\\Phi}^\\mathrm{wire}\\propto\nT^{-1/3}$ and $L_{\\Phi}^\\mathrm{ring}\\propto T^{-1/2}$. This difference\nreflects the fact that the electrons winding around the ring necessarily\nexplore the whole sample (ergodic trajectories), while in a long wire the\nelectrons lose their phase coherence before reaching the edges of the sample\n(diffusive regime).",
        "positive": "How long does it take for the Kondo effect to develop?: The time-development of the Kondo effect is theoretically investigated by\nstudying a quantum dot suddenly shifted into the Kondo regime by a change of\nvoltage on a nearby gate. Using time-dependent versions of both the Anderson\nand Kondo Hamiltonians, it is shown that after a time $t$ following the voltage\nshift, the form of the Kondo resonance matches the {\\it time-independent}\nresonance at an effective temperature $T_{eff} = T/\\tanh(\\pi T t/2)$. Relevance\nof the buildup of the Kondo resonance to the transport current through a\nquantum dot is demonstrated."
    },
    {
        "anchor": "Photoconductiviy of 2D Rashba system in the perpendicular AC magnetic\n  field: The response of a 2D electron system to a DC measurement electric field has\nbeen investigated in the case when the system is driven out of the equilibrium\nby the magnetic ultra-high frequency field that leads to combined transitions\ninvolving the spin-orbit interaction. It has been shown that the method of\nnon-equilibrium statistical operator in conjunction ith the method of canonical\ntransformations allows one to build a theory of linear response of a\nnon-equilibrium 2D electron gas to a weak \"measurement\" DC electric field. The\nproposed theory predicts that such perturbation of the electron system with\nhigh (~10^7 cm^2/Vs) mobility leads to a new type of 2D electron gas\nconductivity oscillations controlled by the ratio of the radiation frequency to\nthe cyclotron frequency.",
        "positive": "Spin-Hall Torques Generated by Rare-Earth (Lanthanide) Thin Films: We report an initial experimental survey of spin-Hall torques generated by\nthe rare-earth metals Gd, Dy, Ho, and Lu, along with comparisons to\nfirst-principles calculations of their spin Hall conductivities. Using spin\ntorque ferromagnetic resonance (ST-FMR) measurements and DC-biased ST-FMR, we\nestimate lower bounds for the spin-Hall torque ratio, $\\xi_{SH}$, of $\\approx$\n0.04 for Gd, $\\approx$ 0.05 for Dy, $\\approx$ 0.14 for Ho, and $\\approx$ 0.014\nfor Lu. The variations among these elements are qualitatively consistent with\nresults from first principles (density functional theory, DFT, in the local\ndensity approximation with a Hubbard-U correction). The DFT calculations\nindicate that the spin Hall conductivity is enhanced by the presence of the\npartially-filled $f$ orbitals in Dy and Ho, which suggests a strategy to\nfurther strengthen the contribution of the $f$ orbitals to the spin Hall effect\nby shifting the electron chemical potential."
    },
    {
        "anchor": "Efficient high-harmonic generation in graphene with two-color laser\n  field at orthogonal polarization: High-order frequency mixing in graphene using a two-color radiation field\nconsisting of the fundamental and the second harmonic fields of an ultrashort\nlinearly polarized laser pulse is studied. It is shown that the harmonics\noriginated from the interband transitions are efficiently generated in the case\nof the orthogonally polarized two-color field. In this case, the generated\nhigh-harmonics are stronger than those obtained in the parallel polarization\ncase by more than two orders of magnitude. This is in sharp contrast with the\natomic and semiconductor systems, where parallel polarization case is more\npreferable. The physical origin of this enhancement is also deduced from the\nthree-step semi-classical electron-hole collision model, extended to graphene\nwith pseudo-relativistic energy dispersion. In particular, we discuss the\ninfluence of the many particle Coulomb interaction on the HHG process within\ndynamical Hartree-Fock approximation. Our analysis shows that in all cases we\nhave an overall enhancement of the HHG signal compared with the free-charged\ncarrier model due to the electron-hole attractive interaction.",
        "positive": "Electron Spin Resonance in a Two-Dimensional Fermi Liquid with\n  Spin-Orbit Coupling: Electron spin resonance (ESR) is usually interpreted as a single-particle\nphenomenon protected from the effect of many-body correlations. We show that\nthis is not the case in a two-dimensional Fermi liquid (FL) with spin-orbit\ncoupling (SOC). Depending on whether the magnetic field is below or above some\ncritical value, ESR in such a system probes up to three collective chiral-spin\nmodes, augmented by the presence of the field, or the Larmor mode, augmented\nboth by SOC and FL renormalizations. We argue that ESR can be used as a probe\nnot only for SOC but also for many-body physics."
    },
    {
        "anchor": "Anomalous Exponent of the Spin Correlation Function of a Quantum Hall\n  Edge: The charge and spin correlation functions of partially spin-polarized edge\nelectrons of a quantum Hall bar are studied using effective Hamiltonian and\nbosonization techniques. In the presence of the Coulomb interaction between the\nedges with opposite chirality we find a different crossover behavior in spin\nand charge correlation functions. The crossover of the spin correlation\nfunction in the Coulomb dominated regime is characterized by an anomalous\nexponent, which originates from the finite value of the effective interaction\nfor the spin degree of freedom in the long wavelength limit. The anomalous\nexponent may be determined by measuring nuclear spin relaxation rates in a\nnarrow quantum Hall bar or in a quantum wire in strong magnetic fields.",
        "positive": "Voltage-Gate Assisted Spin-Orbit Torque Magnetic Random Access Memory\n  for High-Density and Low-Power Embedded Application: Voltage-gate assisted spin-orbit torque (VGSOT) writing scheme combines the\nadvantages from voltage control of magnetic anisotropy (VCMA) and spin-orbit\ntorque (SOT) effects, enabling multiple benefits for magnetic random access\nmemory (MRAM) applications. In this work, we give a complete description of\nVGSOT writing properties on perpendicular magnetic tunnel junction (pMTJ)\ndevices, and we propose a detailed methodology for its electrical\ncharacterization. The impact of gate assistance on the SOT switching\ncharacteristics are investigated using electrical pulses down to 400ps. The\nVCMA coefficient ({\\xi}) extracted from current switching scheme is found to be\nthe same as that from the magnetic field switch method, which is in the order\nof 15fJ/Vm for the 80nm to 150nm devices. Moreover, as expected from the pure\nelectronic VCMA effect, {\\xi} is revealed to be independent of the writing\nspeed and gate length. We observe that SOT switching current characteristics\nare modified linearly with gate voltage (V_g), similar as for the magnetic\nproperties. We interpret this linear behavior as the direct modification of\nperpendicular magnetic anisotropy (PMA) and nucleation energy induced by VCMA.\nAt V_g = 1V, the SOT write current is decreased by 25%, corresponding to a 45%\nreduction in total energy down to 30fJ/bit at 400ps speed for the 80nm devices\nused in this study. Further, the device-scaling criteria are proposed, and we\nreveal that VGSOT scheme is of great interest as it can mitigate the complex\nmaterial requirements of achieving high SOT and VCMA parameters for scaled\nMTJs. Finally, how that VGSOT-MRAM can enable high-density arrays close to two\nterminal geometries, with high-speed performance and low-power operation,\nshowing great potential for embedded memories as well as in-memory computing\napplications at advanced technology nodes."
    },
    {
        "anchor": "A Microscopic Explanation of Microwave Spin Pumping: We contend that Microwave Spin Pumping was first predicted and observed -\nalbeit using a different and more sensitive detection mechanism than Inverse\nSpin Hall Effect - in the 1950's. This discovery was the founding step in the\nwidely used analytical tool that is now known as Dynamic Nuclear Polarisation.\nRecognising this hitherto unsung connection between 20th Century Magnetic\nResonance and 21st Century Spintronics not only helps to explain and unify\ncontemporary metallic spin pumping observations: it is also the key to\nunlocking the immense and very sophisticated toolbox of Magnetic Resonance and\nplacing it at the disposal of the future of Spintronics.",
        "positive": "Photoluminescence of nanocrystals embedded in oxide matrices: We used the theory of finite periodic systems to explain the\nphotoluminescence spectra dependence on the average diameter of nanocrystals\nembedded in oxide matrices. Because of the broad matrix band gap, the\nphotoluminescence response is basically determined by isolated nanocrystals and\nsequences of a few of them. With this model we were able to reproduce the shape\nand displacement of the experimentally observed photoluminescence spectra."
    },
    {
        "anchor": "Distinctive signatures of the spin- and momentum-forbidden dark exciton\n  states in the photo-luminescences of strained WSe$_2$ monolayers under\n  thermalization: With the both spin and valley degrees of freedom, the low-lying excitonic\nspectra of photo-excited transition-metal dichalcogenide monolayers (TMDC-MLs)\nare featured by rich fine structures, comprising the intra-valley bright\nexciton states as well as various intra- and inter-valley dark ones. The latter\nstates can be classified as those of the spin- and momentum-forbidden dark\nexcitons according to the violated optical selection rules. Because of the\noptical invisibility, the two types of the dark states are in general hardly\nobserved and even distinguished in conventional spectroscopies although their\nimpacts on the optical and dynamical properties of TMDC-MLs have been well\nnoticed. In this Letter, we present a theoretical and computational\ninvestigation of the exciton fine structures and the temperature-dependent\nphoto-luminescence spectra of strained tungsten diselenide monolayers\n(WSe$_2$-MLs) where the intra-valley spin-forbidden dark exciton lies in the\nlowest exciton states and other momentum-forbidden states are in the higher\nenergies that are tunable by external stress. The numerical computations are\ncarried out by solving the Bethe-Salpeter equation for an exciton in a\nWSe$_2$-ML under the stress-control in the tight-binding scheme established\nfrom the first principle computation in the density functional theory.\nAccording to the numerical computation and supportive model analysis, we reveal\nthe distinctive signatures of the spin- and momentum-forbidden exciton states\nof strained WSe$_2$-MLs in the temperature-dependent photo-luminescences and\npresent the guiding principle to infer the relative energetic locations of the\ntwo types of DX's.",
        "positive": "Ultra-Long Homochiral Graphene Nanoribbons Grown Within h-BN Stacks for\n  High-Performance Electronics: Van der Waals encapsulation of two-dimensional materials within hexagonal\nboron nitride (h-BN) stacks has proven to be a promising way to create\nultrahigh-performance electronic devices. However, contemporary approaches for\nachieving van der Waals encapsulation, which involve artificial layer stacking\nusing mechanical transfer techniques, are difficult to control, prone to\ncontamination, and unscalable. Here, we report on the transfer-free direct\ngrowth of high-quality graphene nanoribbons (GNRs) within h-BN stacks. The\nas-grown embedded GNRs exhibit highly desirable features being ultralong (up to\n0.25 mm), ultranarrow ( < 5 nm), and homochiral with zigzag edges. Our\natomistic simulations reveal that the mechanism underlying the embedded growth\ninvolves ultralow GNR friction when sliding between AA'-stacked h-BN layers.\nUsing the grown structures, we demonstrate the transfer-free fabrication of\nembedded GNR field-effect devices that exhibit excellent performance at room\ntemperature with mobilities of up to 4,600 $cm^{2} V^{-1} s^{-1}$ and on-off\nratios of up to $10^{6}$. This paves the way to the bottom-up fabrication of\nhigh-performance electronic devices based on embedded layered materials."
    },
    {
        "anchor": "Attojoule calorimetry of mesoscopic superconducting loops: We report the first experimental evidence of nontrivial thermal behavior of\nthe simplest mesoscopic system - a superconducting loop. By measuring the\nspecific heat C of an array of 450,000 noninteracting aluminum loops with very\nhigh accuracy of ~20 fJ/K, we show that the loops go through a periodic\nsequence of phase transitions (with period of an integer number of magnetic\nflux quanta) as the magnetic flux threading each loop is increased. The\ntransitions are well described by the Ginzburg-Landau theory and are\naccompanied by discontinuities of C of only several thousands of Boltzmann\nconstants k_B.",
        "positive": "Phonon distributions of a single bath mode coupled to a quantum dot: The properties of an unconventional, single mode phonon bath coupled to a\nquantum dot, are investigated within the rotating wave approximation. The\nelectron current through the dot induces an out of equilibrium bath, with a\nphonon distribution qualitatively different from the thermal one. In selected\ntransport regimes, such a distribution is characterized by a peculiar selective\npopulation of few phonon modes and can exhibit a sub-Poissonian behavior. It is\nshown that such a sub-Poissonian behavior is favored by a double occupancy of\nthe dot. The crossover from a unequilibrated to a conventional thermal bath is\nexplored, and the limitations of the rotating wave approximation are discussed."
    },
    {
        "anchor": "Thermoelectric properties of finite two-dimensional quantum dot arrays\n  with band-like electronic states: The thermal power ($PF=S^2G_e$) depends on the Seebeck coefficient ($S$) and\nelectron conductance ($G_e$). The enhancement of $G_e$ will unavoidably\nsuppress $S$ because they are closely related. As a consequence, the\noptimization of $PF$ is extremely difficult. Here, we theoretically\ninvestigated the thermoelectric properties of two-dimensional quantum dot (QD)\narrays with carriers injected from electrodes. The Lorenz number of 2D QD\narrays in the resonant tunneling procedure satisfies the Wiedemann-Franz law,\nwhich confirms the formation of minibands. When the miniband center is far away\nfrom the Fermi level of the electrodes, the electron transport is in the\nthermionic-assisted tunneling procedure (TATP). In this regime, $G_e$ in\nband-like situation and $S$ in atom-like situation can happen simultaneously.\nWe have demonstrated that the enhancement of $G_e$ with an increasing number of\nelectronic states will not suppress $S$ in the TATP.",
        "positive": "Modeling ultrafast all-optical switching in synthetic ferrimagnets: Based on numerical simulations, we demonstrate thermally induced magnetic\nswitching in synthetic ferrimagnets composed of multilayers of rare-earth and\ntransition metals. Our findings show that deterministic magnetization reversal\noccurs above a certain threshold temperature if the ratio of transition metal\natoms to rare-earth atoms is sufficiently large. Surprisingly, the total\nthickness of the multilayer system has little effect on the occurence of\nswitching. We further provide a simple argument to explain the temperature\ndependence of the reversal process."
    },
    {
        "anchor": "Triangular array of iron-oxide nanoparticles: A simulation study of\n  intra- and inter-particle magnetism: A study of spherical maghemite nanoparticles on a two dimensional triangular\narray was carried out using a stochastic Landau-Lifshitz-Gilbert (sLLG)\napproach. The simulation method was first validated with a triangular array of\nsimple dipoles, where results show the expected phase transition to a\nferromagnetic state at a finite temperature. The ground state exhibited a\ncontinuous degeneracy that was lifted by an order-from-disorder mechanism at\ninfinitesimal temperatures with the appearance of a six-fold planar anisotropy.\nThe nanoparticle array consisted of 7.5 nm diameter maghemite spheres with\nbulk-like superexchange interactions between Fe-ions in the core, and weaker\nexchange between surface Fe-ions and a radial anisotropy. The triangular\nnanoparticle array ordered at the same reduced temperature as the simple dipole\narray, but exhibited different behaviour at low temperatures due to the surface\nanisotropy. We find that the vacancies on the octahedral sites in the\nnanoparticles combine with the surface anisotropy to produce an effective\nrandom temperature-dependent anisotropy for each particle. This leads to a\nreduction in the net magnetization of the nanoparticle array at zero\ntemperature compared to the simple dipole array.",
        "positive": "Coherent trapping in small quantum networks: We consider a three-node fully connected network (Delta network) showing that\na coherent population trapping phenomenon occurs, generalizing results for the\nLambda network known to support a dark state. Transport in such structures\nprovides signatures of detrapping, which can be triggered by external controls.\nIn the presence of an environment it turns out to be sensitive to its\nMarkovianity. Adiabatic modulation of the system's parameters may yield\ncoherent population transfer, analogous to the stimulated Raman adiabatic\npassage phenomenon. Robustness of this protocol against non-adiabatic\ntransitions is studied. Coherent nanostructures where these phenomena are\nrelevant for quantum transport and quantum protocols are suggested."
    },
    {
        "anchor": "Towards Substrate Engineering of Graphene-Silicon Schottky Diode\n  Photodetectors: Graphene-Silicon Schottky diode photodetectors possess beneficial properties\nsuch as high responsivities and detectivities, broad spectral wavelength\noperation and high operating speeds. Various routes and architectures have been\nemployed in the past to fabricate devices. Devices are commonly based on the\nremoval of the silicon-oxide layer on the surface of silicon by wet-etching\nbefore deposition of graphene on top of silicon to form the graphene-silicon\nSchottky junction. In this work, we systematically investigate the influence of\nthe interfacial oxide layer, the fabrication technique employed and the silicon\nsubstrate on the light detection capabilities of graphene-silicon Schottky\ndiode photodetectors. The properties of devices are investigated over a broad\nwavelength range from near-UV to short-/mid-infrared radiation, radiation\nintensities covering over five orders of magnitude as well as the suitability\nof devices for high speed operation. Results show that the interfacial layer,\ndepending on the required application, is in fact beneficial to enhance the\nphotodetection properties of such devices. Further, we demonstrate the\ninfluence of the silicon substrate on the spectral response and operating\nspeed. Fabricated devices operate over a broad spectral wavelength range from\nthe near-UV to the short-/mid-infrared (thermal) wavelength regime, exhibit\nhigh photovoltage responses approaching 10$^6$ V/W and short rise- and\nfall-times of tens of nanoseconds.",
        "positive": "Complete steric exclusion of ions and proton transport through confined\n  monolayer water: It has long been an aspirational goal to create artificial structures that\nallow fast permeation of water but reject even the smallest hydrated ions,\nreplicating the feat achieved by nature in protein channels (e.g., aquaporins).\nDespite recent progress in creating nanoscale pores and capillaries, these\nstructures still remain distinctly larger than protein channels. We report\ncapillaries made by effectively extracting one atomic plane from bulk crystals,\nwhich leaves a two-dimensional slit of a few angstroms in height. Water moves\nthrough these capillaries with little resistance, whereas no permeation could\nbe detected even for such small ions as Na+ and Cl-. Only protons (H+) can\ndiffuse through monolayer water inside the capillaries. These observations\nimprove our understanding of molecular transport at the atomic scale."
    },
    {
        "anchor": "Temperature-Dependent Magnetization Reversal in Exchange Bias\n  NiFe/IrMn/NiFe Structures: We demonstrate the magnetization reversal features in NiFe/IrMn/NiFe\nthin-film structures with 40% and 75% relative content of Ni in Permalloy in\nthe temperature range from 80 K to 300 K. At the descending branches of the\nhysteresis loops, the magnetization reversal sequence of the two ferromagnetic\nlayers is found to depend on the type of NiFe alloy. In the samples with 75%\nrelative content of Ni, the bottom ferromagnetic layer reverses prior to the\ntop one. On the contrary, in the samples with 40% of Ni, the top ferromagnetic\nlayer reverses prior to the bottom one. These tendencies of magnetization\nreversal are preserved in the entire range of temperatures. These distinctions\ncan be explained by the morphological and structural differences of interfaces\nin the samples based on two types of Permalloy.",
        "positive": "Thermionic Emission as a tool to study transport in undoped nFinFETs: Thermally activated sub-threshold transport has been investigated in undoped\ntriple gate MOSFETs. The evolution of the barrier height and of the active\ncross-section area of the channel as a function of gate voltage has been\ndetermined. The results of our experiments and of the Tight Binding simulations\nwe have developed are both in good agreement with previous analytical\ncalculations, confirming the validity of thermionic approach to investigate\ntransport in FETs. This method provides an important tool for the improvement\nof devices characteristics."
    },
    {
        "anchor": "Level crossings and zero-field splitting in the \\{Cr$_8$\\}-cubane\n  spin-cluster by inelastic neutron scattering and magnetization studies: Inelastic neutron scattering in variable magnetic field and high-field\nmagnetization measurements, at the milikelvin temperature range, were performed\nto gain insight into the low-energy magnetic excitation spectrum and the\nfield-induced level crossings in the molecular spin cluster \\{Cr$_8$\\}-cubane.\nThese complementary techniques provide consistent estimates of the lowest\nlevel-crossing field. The overall features of the experimental data are\nexplained using an isotropic Heisenberg model, based on three distinct exchange\ninteractions linking the eight Cr$^{\\text{III}}$ paramagnetic centers (spins $s\n= 3/2$), that is supplemented with a relatively large molecular magnetic\nanisotropy term for the lowest S=1 multiplet. It is noted that the existence of\nthe anisotropy is clearly evident from the magnetic field dependence of the\nexcitations in the INS measurements, while the magnetization measurements are\nnot sensitive to its effects.",
        "positive": "The Casimir-Polder effect for a stack of conductive planes: The Casimir-Polder interaction between an atom and a multilayered system\ncomposed of infinitely thin planes is considered using the zeta-function\nregularization approach with summation of the zero-point energies. As a\nprototype material, each plane is represented by a graphene sheet whose optical\nresponse is described by a constant conductivity or Drude-Lorentz model\nconductivity. Asymptotic expressions for various separations are derived and\ncompared to numerical calculations. We distinguish between large atom/plane\nlimit, where retardation effects are prominent, and small atom/plane limit,\nwhere the typical van der Waals coefficient is found to be dependent on the\nnumber of graphenes and characteristic distances. The calculated energies for\ndifferent atoms and graphene conductivity models brings forward the basic\nscience of the Casimir-Polder effect and suggests ways to manipulate this\ninteraction experimentally."
    },
    {
        "anchor": "Zero-field spin wave turns: Spin-wave computing, a potential successor to CMOS-based technologies, relies\non the efficient manipulation of spin waves for information processing. While\nbasic logic devices like magnon transistors, gates, and adders have been\nexperimentally demonstrated, the challenge for complex magnonic circuits lies\nin steering spin waves through sharp turns. In this study we demonstrate with\nmicromagnetic simulations and Brillouin light scattering microscopy\nexperiments, that dipolar spin waves can propagate through 90-degree turns\nwithout distortion. The key lies in carefully designed in-plane magnetization\nlandscapes, addressing challenges posed by anisotropic dispersion. The\nexperimental realization of the required magnetization landscape is enabled by\nspatial manipulation of the uniaxial anisotropy using corrugated magnonic\nwaveguides. The findings presented in this work should be considered in any\nmagnonic circuit design dealing with anisotropic dispersion and spin wave\nturns.",
        "positive": "Edge magnetoplasmon excitations in a Quantum Dot in high magnetic fields: We investigate the collective magnetoplasmon excitations in a quantum dot\ncontaining finite number of electrons in the high magnetic field limit. We\nconsider the electrons in the lowest Landau level and neglect mixing between\nthe higher Landau levels. The dispersion relation of these edge modes are\nestimated following the energy weighted sum-rule approach. In this finite size\nsystem the edge magnetoplasmon modes have different multipolarities (or angular\nmomemtum l). Their dependence on the magnetic field and on the system size is\ninvestigated. With increasing magnetic field, energy of these collective modes\ndecreases and in the bulk limit they become gapless. We also consider the\nbreathing mode of a dot in the presence of a strong magnetic field, and the\nenergy of this mode approaches the cyclotron frequency $\\hbar \\omega_{c}$."
    },
    {
        "anchor": "Electrochemical Shot-Noise of a Redox Monolayer: Redox monolayers are the base for a wide variety of devices including\nhigh-frequency molecular diodes or biomolecular sensors. We introduce a\nformalism to describe the electrochemical shot-noise of such monolayer,\nconfirmed experimentally at room temperature in liquid. The proposed method,\ncarried out at equilibrium, avoids parasitic capacitance, increases the\nsensitivity and allows to obtain quantitative information such as the\nelectronic coupling (or standard electron transfer rates), its dispersion and\nthe number of molecules. Unlike in solid-state physics, the homogeneity in\nenergy levels and transfer rates in the monolayer yields a Lorentzian spectrum.\nThis first step for shot-noise studies in molecular electrochemical systems\nopens perspectives for quantum transport studies in liquid environment at room\ntemperature as well as highly sensitive measurements for bioelectrochemical\nsensors.",
        "positive": "Topological luminophor Y2O3:Eu3++Ag with high electroluminescence\n  performance: Improving luminescent intensity is a significant technical requirement and\nscientific problem for the luminescent performance of fluorophor materials\nthrough the ages. The process control and luminescence performance still limit\nthe developments of luminescent intensity even through it can be improved\npartly by covering or magnetron sputtering of precious metals on the surface of\nthe fluorophore materials. On the basis of the improvement of luminescence\ncenter radiative transition rate by surface plasma resonance and Y2O3:Eu3+\nmicrosheet phosphors, a fundamental model for topological luminophor\nY2O3:Eu3++Ag was designed referencing the concepts of topological materials in\norder to enhance luminescent performance by composite-luminescence, which\ncomposed of Eu3+centric electroluminescence and surface plasma-enhanced\nphotoluminescence by Ag. The topological luminophor Y2O3:Eu3++Ag was\nsuccessfully synthesized with an asymmetric-discrete Ag nanocrystal topological\nstructure on the surface just via illumination. Experiment results suggest that\nthe luminescence performance of topological luminophor Y2O3:Eu3++Ag increased\nby about 300% compared with that of Y2O3: Eu3+ phosphors on the same\nconditions. The design of a topological luminophor provides a new approach to\nfurther improve the luminescent intensity of phosphors."
    },
    {
        "anchor": "Interfacial Coupling and Electronic Structure of Two-Dimensional Silicon\n  Grown on the Ag(111) Surface at High Temperature: Freestanding silicene, a monolayer of Si arranged in a honeycomb structure,\nhas been predicted to give rise to massless Dirac fermions, akin to graphene.\nHowever, Si structures grown on a supporting substrate can show properties that\nstrongly deviate from the freestanding case. Here, combining scanning tunneling\nmicroscopy/spectroscopy and differential conductance mapping, we show that the\nelectrical properties of the ($\\sqrt{3}\\times\\sqrt{3}$) phase of few-layer Si\ngrown on Ag(111) strongly depend on film thickness, where the electron phase\ncoherence length decreases and the free-electron-like surface state gradually\ndiminishes when approaching the interface. These features are presumably\nattributable to the inelastic inter-band electron-electron scattering\noriginating from the overlap between the surface state, interface state and the\nbulk state of the substrate. We further demonstrate that the intrinsic\nelectronic structure of the as grown ($\\sqrt{3}\\times\\sqrt{3}$) phase is\nidentical to that of the ($\\sqrt{3}\\times\\sqrt{3}$)R$30^{\\circ}$ reconstructed\nAg on Si(111), both of which exhibit the parabolic energy-momentum dispersion\nrelation with comparable electron effective masses. These findings highlight\nthe essential role of interfacial coupling on the properties of two-dimensional\nSi structures grown on supporting substrates, which should be thoroughly\nscrutinized in pursuit of silicene.",
        "positive": "Energy spectrum and broken spin-surface locking in topological insulator\n  quantum dots: We consider the energy spectrum and the spin-parity structure of the\neigenstates for a quantum dot made of a strong topological insulator. Using the\neffective low-energy theory in a finite-length cylinder geometry, numerical\ncalculations show that even at the lowest energy scales, the spin direction in\na topologically protected surface mode is not locked to the surface. We find\n\"zero-momentum\" modes, and subgap states localized near the \"caps\" of the dot.\nBoth the energy spectrum and the spin texture of the eigenstates are basically\nreproduced from an analytical surface Dirac fermion description. Our results\nare compared to microscopic calculations using a tight-binding model for a\nstrong topological insulator in a finite-length nanowire geometry."
    },
    {
        "anchor": "Induced topological order at the boundary of 3D topological\n  superconductors: We present tight-binding models of 3D topological superconductors in class\nDIII that support a variety of winding numbers. We show that gapless Majorana\nsurface states emerge at their boundary in agreement with the bulk-boundary\ncorrespondence. At the presence of a Zeeman field the surface states become\ngapped and the boundary behaves as a 2D superconductor in class D. Importantly,\nthe 2D and 3D winding numbers are in agreement signifying that the topological\norder of the boundary is induced by the order of the 3D bulk. Hence, the\nboundary of a 3D topological superconductor in class DIII can be used for the\nrobust realisation of localised Majorana zero modes.",
        "positive": "Stabilization of molecular hydrogen-bonded chains by carbon nanotubes: We study numerically nonlinear dynamics of several types of molecular systems\ncomposed of hydrogen-bonded chains placed inside carbon nanotubes with open\nedges. We demonstrate that carbon nanotubes provide a stabilization mechanism\nfor quasi-one-dimensional molecular chains via the formation of their secondary\nstructures. In particular, a polypeptide chain (Gly)$_N$ placed inside a carbon\nnanotube can form of a stable helical chain ($3_{10}$, $\\alpha$, $\\pi$ and\n$\\beta$-helix) with parallel chains of hydrogen-bonded peptide groups. A chain\nof hydrogen fluoride molecules can form hydrogen-bonded zigzag chain. We reveal\nthat in such geometries the hydrogen-bonded chains may remain stable even at\n$T=500$~K. Thus, our results suggest that the use of carbon nanotubes with\nencapsulated hydrogen fluoride molecules may support high proton conductivity\noperating at high temperatures."
    },
    {
        "anchor": "Van Hove Singularities and Excited-State Quantum Phase Transitions in\n  Graphene-like Microwave Billiards: We discuss solutions of an algebraic model of the hexagonal lattice\nvibrations, which point out interesting localization properties of the\neigenstates at van Hove singularities (vHs), whose energies correspond to\nExcited-State Quantum Phase Transitions (ESQPT). We show that these states form\nstripes oriented parallel to the zig-zag direction of the lattice, similar to\nthe well-known edge states found at the Dirac point, however the vHs-stripes\nappear in the bulk. We interpret the states as lines of cell-tilting\nvibrations, and inspect their stability in the large lattice-size limit. The\nmodel can be experimentally realized by superconducting 2D microwave resonators\ncontaining triangular lattices of metallic cylinders, which simulate\nfinite-sized graphene flakes. Thus we can assume that the effects discussed\nhere could be experimentally observed.",
        "positive": "High-performance and Low-power Transistors Based on Anisotropic\n  Monolayer $\u03b2$-TeO$_2$: Two-dimensional (2D) semiconductors offer a promising prospect for\nhigh-performance and energy-efficient devices especially in the sub-10 nm\nregime. Inspired by the successful fabrication of 2D $\\beta$-TeO$_2$ and the\nhigh on/off ratio and high air-stability of fabricated field effect transistors\n(FETs) [Nat. Electron. 2021, 4, 277], we provide a comprehensive investigation\nof the electronic structure of monolayer $\\beta$-TeO$_2$ and the device\nperformance of sub-10 nm metal oxide semiconductors FETs (MOSFETs) based on\nthis material. The anisotropic electronic structure of monolayer\n$\\beta$-TeO$_2$ plays a critical role in the anisotropy of transport properties\nfor MOSFETs. We show that the 5.2-nm gate-length n-type MOSFET holds an\nultra-high on-state current exceeding 3700 {\\mu}A/{\\mu}m according to\nInternational Roadmap for Devices and Systems (IRDS) 2020 goals for\nhigh-performance devices, which is benefited by the highly anisotropic electron\neffective mass. Moreover, monolayer $\\beta$-TeO$_2$ MOSFETs can fulfill the\nIRDS 2020 goals for both high-performance and low-power devices in terms of\non-state current, sub-threshold swing, delay time, and power-delay product.\nThis study unveils monolayer $\\beta$-TeO$_2$ as a promising candidate for\nultra-scaled devices in future nanoelectronics."
    },
    {
        "anchor": "Quantum Transport in Disorderd Mesoscopic Ferromagnetic Films: The effect of impurity and domain-wall scattering on the electrical\nconductivity of disordered mesoscopic magnetic thin films is studied by use of\ncomputer simulation. The results indicate a reduction of resistivity due to a\ndomain wall, which is consistent with the explanation in terms of the dephasing\ncaused by domain wall.",
        "positive": "Hybrid light-matter networks of Majorana zero modes: Topological excitations, such as Majorana zero modes, are a promising route\nfor encoding quantum information. Topologically protected gates of Majorana\nqubits, based on their braiding, will require some form of network. Here, we\npropose to build such a network by entangling Majorana matter with light in a\nmicrowave cavity QED setup. Our scheme exploits a light-induced interaction\nwhich is universal to all the Majorana nanoscale circuit platforms. This effect\nstems from a parametric drive of the light-matter coupling in a one-dimensional\nchain of physical Majorana modes. Our setup enables all the basic operations\nneeded in a Majorana quantum computing platform such as fusing, braiding, the\ncrucial T-gate, the read-out and, importantly, the stabilization or correction\nof the physical Majorana modes."
    },
    {
        "anchor": "Spin and charge transport in graphene-based spin transport devices with\n  Co/MgO spin injection and spin detection electrodes: In this review we discuss spin and charge transport properties in\ngraphene-based single-layer and few-layer spin-valve devices. We give an\noverview of challenges and recent advances in the field of device fabrication\nand discuss two of our fabrication methods in more detail which result in\ndistinctly different device performances. In the first class of devices, Co/MgO\nelectrodes are directly deposited onto graphene which results in rough\nMgO-to-Co interfaces and favor the formation of conducting pinholes throughout\nthe MgO layer. We show that the contact resistance area product (R$_c$A) is a\nbenchmark for spin transport properties as it scales with the measured spin\nlifetime in these devices indicating that contact-induced spin dephasing is the\nbottleneck for spin transport even in devices with large R$_c$A values. In a\nsecond class of devices, Co/MgO electrodes are first patterned onto a silicon\nsubstrate. Subsequently, a graphene-hBN heterostructure is directly transferred\nonto these prepatterned electrodes which provides improved interface\nproperties. This is seen by a strong enhancement of both charge and spin\ntransport properties yielding charge carrier mobilities exceeding 20000\ncm$^2$/(Vs) and spin lifetimes up to 3.7 ns at room temperature. We discuss\nseveral shortcomings in the determination of both quantities which complicates\nthe analysis of both extrinsic and intrinsic spin scattering mechanisms.\nFurthermore, we show that contacts can be the origin of a second charge\nneutrality point in gate dependent resistance measurements which is influenced\nby the quantum capacitance of the underlying graphene layer.",
        "positive": "Scrambling of Hartree-Fock Levels as a universal Brownian-Motion Process: We study scrambling of the Hartree-Fock single-particle levels and wave\nfunctions as electrons are added to an almost isolated diffusive or chaotic\nquantum dot with electron-electron interactions. We use the generic framework\nof the induced two-body ensembles where the randomness of the two-body\ninteraction matrix elements is induced by the randomness of the eigenfunctions\nof the chaotic or diffusive single-particle Hamiltonian. After an appropriate\nscaling of the number of added electrons, the scrambling of both the HF levels\nand wave functions is described by a universal function each. These functions\ncan be derived from a parametric random matrix process of the Brownian-motion\ntype. An exception to this universality occurs when an empty level just gets\nfilled, in which case scrambling is delayed by one electron. An explanation of\nthese results is given in terms of a generalized Koopmans' approach."
    },
    {
        "anchor": "Quantum Dynamics of Coupled Bosonic Wells within the Bose-Hubbard\n  Picture: We relate the quantum dynamics of the Bose-Hubbard model (BHM) to the\nsemiclassical nonlinear equations that describe an array of interacting Bose\ncondensates by implementing a standard variational procedure based on the\ncoherent state method. We investigate the dynamics of the two-site BHM from the\npurely quantum viewpoint by recasting first the model within a spin picture and\nusing then the related dynamical algebra. The latter allows us to study\nthoroughly the energy spectrum structure and to interpret quantally the\nclassical symmetries of the two-site dynamics. The energy spectrum is also\nevaluated through various approximations relying on the coherent state\napproach.",
        "positive": "Admittance and Nonlinear Transport in Quantum Wires, Point Contacts, and\n  Resonant Tunneling Barriers: We present a discussion of the admittance (ac-conductance) and nonlinear\nI-V-characteristic for a number of mesoscopic conductors. Our approach is based\non a generalization of the scattering approach which now includes the effects\nof the (long-range) Coulomb interaction. We discuss the admittance of a wire\nwith an impurity and with a nearby gate. We extend a discussion of the\nlow-frequency admittance of a quantum point contact to investigate the effects\nof the gates used to form the contact. We discuss the nonlinear I-V\ncharacteristic of a resonant double barrier structure and discuss the\nadmittance for the double barrier for a large range of frequencies. Our\napproach emphasizes the overall conservation of charge (gauge invariance) and\ncurrent conservation and the resulting sum rules for the admittance matrix and\nnonlinear transport coefficients."
    },
    {
        "anchor": "Non Equilibrium Green's Functions for Dummies: Introduction to the One\n  Particle NEGF equations: Non equilibrium Green's function methods are regularly used to calculate\ncurrent and charge densities in nanoscale (both molecular and semiconductor)\nconductors under bias. This method is mainly used for ballistic conduction but\nmay be extended to include inelastic scattering. In this tutorial paper the\nNEGF equations for the current and charge density matrix are derived and\nexplained in a hopefully clear way.",
        "positive": "Confined magnetoelastic waves in thin waveguides: The characteristics of confined magnetoelastic waves in nanoscale\nferromagnetic magnetostrictive waveguides have been investigated by a\ncombination of analytical and numerical calculations. The presence of both\nmagnetostriction and inverse magnetostriction leads to the coupling between\nconfined spin waves and elastic Lamb waves. Numerical simulations of the\ncoupled system have been used to extract the dispersion relations of the\nmagnetoelastic waves as well as their mode profiles."
    },
    {
        "anchor": "Graphene transparency in weak magnetic fields: We carry out an explicit calculation of the vacuum polarization tensor for an\neffective low-energy model of monolayer graphene in the presence of a weak\nmagnetic field of intensity $B$ perpendicularly aligned to the membrane. By\nexpanding the quasiparticle propagator in the Schwinger proper time\nrepresentation up to order $(eB)^2$, where $e$ is the unit charge, we find an\nexplicitly transverse tensor, consistent with gauge invariance. Furthermore,\nassuming that graphene is radiated with monochromatic light of frequency\n$\\omega$ along the external field direction, from the modified Maxwell's\nequations we derive the intensity of transmitted light and the angle of\npolarization rotation in terms of the longitudinal ($\\sigma_{xx}$) and\ntransverse ($\\sigma_{xy}$) conductivities. Corrections to these quantities,\nboth calculated and measured, are of order $(eB)^2/\\omega^4$. Our findings\ngeneralize and complement previously known results reported in literature\nregarding the light absorption problem in graphene from the experimental and\ntheoretical points of view, with and without external magnetic fields.",
        "positive": "Plasmons in finite spherical ionic systems: The challenging question on possible plasmon type excitations in finite ionic\nsystems is discussed. The related theoretical model is formulated and developed\nin order to describe surface and volume plasmons of ion liquid in finite\nelectrolyte systems. The irradiation of ionic surface plasmon fluctuations is\nstudied in terms of the Lorentz friction of oscillating charges. The\nattenuation of surface plasmons in the ionic sphere is calculated and minimized\nwith respect to the sphere size. Various regimes of approximation for\ndescription of size effect for damping of ionic plasmons are determined and a\ncross-over in damping size-dependence is demonstrated. The most convenient\ndimension of finite electrolyte system for energy and information transfer by\nusage of ionic dipole plasmons is determined. The overall shift of size effect\nto micrometer scale for ions in comparison to nanometer scale for electrons in\nmetals is found and by several orders red shift of plasmonic resonances in ion\nsystems is predicted in a wide range of variation depending of ion system\nparameters. This convenient opportunity of tuning of resonances differs ionic\nplasmons from plasmons in metals where electron concentration was firmly fixed."
    },
    {
        "anchor": "Corner states of light in photonic waveguides: The recently established paradigm of higher-order topological states of\nmatter has shown that not only, as previously thought, edge and surface states\nbut also states localised to corners can have robust and exotic properties.\nHere we report on the experimental realisation of novel corner states made out\nof classical light in three-dimensional photonic structures inscribed in glass\nsamples using femtosecond (fs) laser technology. By creating and analysing\nwaveguide arrays forming two-dimensional breathing kagome lattices in various\nsample geometries, we establish this as a platform for corner states exhibiting\na remarkable degree of flexibility and control. In each sample geometry we\nmeasure eigenmodes that are localised at the corners in a finite frequency\nrange in complete analogy with a theoretical model of the breathing kagome.\nHere, the measurements reveal that light can be \"fractionalised\", corresponding\nto simultaneous localisation to each corner of a triangular sample, even in the\npresence of defects. The fabrication method applied in this work exposes the\nadvantage of using fs-laser writing for producing compact three-dimensional\ndevices thus paving the way for technological applications by simulating novel\nhigher-order states of matter.",
        "positive": "Systematic approach to statistics of conductance and shot-noise in\n  chaotic cavities: Applying random matrix theory to quantum transport in chaotic cavities, we\ndevelop a novel approach to computation of the moments of the conductance and\nshot-noise (including their joint moments) of arbitrary order and at any number\nof open channels. The method is based on the Selberg integral theory combined\nwith the theory of symmetric functions and is applicable equally well for\nsystems with and without time-reversal symmetry. We also compute higher-order\ncumulants and perform their detailed analysis. In particular, we establish an\nexplicit form of the leading asymptotic of the cumulants in the limit of the\nlarge channel numbers. We derive further a general Pfaffian representation for\nthe corresponding distribution functions. The Edgeworth expansion based on the\nfirst four cumulants is found to reproduce fairly accurately the distribution\nfunctions in the bulk even for a small number of channels. As the latter\nincreases, the distributions become Gaussian-like in the bulk but are always\ncharacterized by a power-law dependence near their edges of support. Such\nasymptotics are determined exactly up to linear order in distances from the\nedges, including the corresponding constants."
    },
    {
        "anchor": "Gaussian deformations in graphene ribbons: flowers and confinement: The coupling of geometrical and electronic properties is a promising venue to\nengineer conduction properties in graphene. Confinement added to strain allows\nfor interplay of different transport mechanisms with potential device\napplications. To investigate strain signatures on transport in confined\ngeometries, we focus on graphene nanoribbons (GNR) with circularly symmetric\ndeformations. In particular, we study GNR with an inhomogeneous, out of plane\nGaussian deformation, connected to reservoirs. We observe an enhancement of the\ndensity of states in the deformed region, accompanied with a decrease in the\nconductance, signaling the presence of confined states. The local density of\nstates exhibits a six-fold symmetric structure with an oscillating sub-lattice\noccupation asymmetry, that persist for a wide range of energy and model\nparameters.",
        "positive": "Dark states in spin-polarized transport through triple quantum dot\n  molecules: We study the spin-polarized transport through a triple quantum dot molecule\nweakly coupled to ferromagnetic leads. The analysis is performed by means of\nthe real-time diagrammatic technique including up to the second order of\nperturbation expansion with respect to the tunnel coupling. The emphasis is put\non the impact of dark states on spin-resolved transport characteristics. It is\nshown that the interplay of coherent population trapping and cotunneling\nprocesses results in a highly nontrivial behavior of the tunnel\nmagnetoresistance, which can take negative values. Moreover, a super-Poissonian\nshot noise is found in transport regimes where the current is blocked by the\nformation of dark states, which can be additionally enhanced by spin-dependence\nof tunneling processes, depending on magnetic configuration of the device. The\nmechanisms leading to those effects are thoroughly discussed."
    },
    {
        "anchor": "MnSi-nanostructures obtained from thin films: magnetotransport and Hall\n  effect: We present a comparative study of the (magneto)transport properties,\nincluding Hall effect, of bulk, thin film and nanostructured MnSi. In order to\nset our results in relation to published data we extensively characterize our\nmaterials, this way establishing a comparatively good sample quality. Our\nanalysis reveals that in particular for thin film and nanostructured material,\nthere are extrinsic and intrinsic contributions to the electronic transport\nproperties, which by modeling the data we separate out. Finally, we discuss our\nHall effect data of nanostructured MnSi under consideration of the extrinsic\ncontributions and with respect to the question of the detection of a\ntopological Hall effect in a skyrmionic phase.",
        "positive": "Electron correlations and silicon nanocluster energetics: The first-principle prediction of nanocluster stable structure is often\nhampered by the existence of many isomer configurations with energies close to\nthe ground state. This fact attaches additional importance to many-electron\neffects going beyond density functional theory (DFT), because their\ncontributions may change a subtle energy order of competitive structures. To\nanalyze this problem, we consider, as an example, the energetics of silicon\nnanoclusters passivated by hydrogen Si$_{10}$H$_{2n}$ with $0\\le n\\le 11$, the\nstructure of which varies with passivation from compact to loose-packed,\nsimilar to branching polymers. Our calculations performed by the DFT, hybrid\nfunctionals and Hartree-Fock (H-F) methods, as well as by the GW approximation\n(GWA), confirm a considerable sensitivity of structure prediction and isomer\nenergy ordering to many-electron effects and show some results which may be\nobtained with the methods less computationally demanding than the GWA."
    },
    {
        "anchor": "Strongly enhanced shot noise in chains of quantum dots: We study charge transport through a chain of quantum dots. The dots are fully\ncoherent among each other and weakly coupled to metallic electrodes via the\ndots at the interface, thus modelling a molecular wire. If the non-local\nCoulomb interactions dominate over the inter-dot hopping we find strongly\nenhanced shot noise above the sequential tunneling threshold. The current is\nnot enhanced in the region of enhanced noise, thus rendering the noise\nsuper-Poissonian. In contrast to earlier work this is achieved even in a fully\nsymmetric system. The origin of this novel behavior lies in a competition of\n\"slow\" and \"fast\" transport channels that are formed due to the differing\nnon-local wave functions and total spin of the states participating in\ntransport. This strong enhancement may allow direct experimental detection of\nshot noise in a chain of lateral quantum dots.",
        "positive": "Fractional quantum Hall effect and electron correlations in partially\n  filled first excited Landau level: We present a quantitative study of most prominent incompressible quantum Hall\nstates in the partially filled first excited Landau level (LL1) which have been\nrecently studied experimentally by Choi et al. The pseudopotential describing\nthe electron - electron interaction in LL1 is harmonic at short range. It\nproduces a series of incompressible states which is different from its LL0\ncounterpart. The numerical data indicate that the most prominent states\n$\\nu={5/2}$, 7/3, and 8/3 are not produced by Laughlin correlated electrons,\nbut result from a tendency of electrons to form pairs or larger clusters which\neventually become Laughlin correlated. States with smaller gaps at filling\nfactors 14/5, 16/7, 11/5, 19/7 are Laughlin correlated electron or hole states\nand fit Jain's sequence of filled $\\rm{CF}^4$ levels."
    },
    {
        "anchor": "Magnetic proximity effect induced FMR frequency enhancement in {Py/FeMn}\n  bilayers: Ferromagnetic resonance (FMR) in exchange-coupled ferromagnet-antiferromagnet\n(FM/AFM) bilayers commonly shows a moderate increase in the resonance frequency\nowing to the induced unidirectional anisotropy. Here we report a large FMR\nfrequency enhancement toward the sub-THz range observed in Py/FeMn with\nultrathin AFM FeMn. The effect is connected with a sizable induced magnetic\nmoment in FeMn caused by the magnetic proximity effect from the Py layer. The\nobserved FMR properties are explained as due to the competing intrinsic\nantiferromagnetic order and the ferromagnetic proximity effect in nanometer\nthin FeMn. Our results show that combining materials with strong and weak\nanti/ferromagnetic ordering can potentially close the notoriously difficult\nGHz-THz gap important for high-speed spintronic applications.",
        "positive": "An atomically thin oxide layer on the elemental superconductor Ta(001)\n  surface: Recently the oxygen-reconstructed tantalum surface Ta(001)-p(3$\\times$3)-O\nhas experienced considerable attention due its use as a potential platform for\nMajorana physics in adatom chains. Experimental studies using scanning\ntunneling microscopy and spectroscopy found rich atomic and electronic\nstructures already for the clean Ta(001)-O surface, which we combine here with\n$ab~initio$ methods. We discover two metastable superstructures at the root of\nthe different topographic patterns, discuss its emergence during annealing, and\nidentify the electronic properties. The latter is determined as the sole origin\nfor the contrast reversal seen at positive bias. The observed effects are\nessentially connected to the two distinct oxygen states appearing on the\nsurface in different geometries. The second superstructure was found in\nsimulations by introducing oxygen vacancies, what was also observed in tantalum\npentoxide systems. Additionally we study the charge distribution on the\noxidized surface and underline its importance for the adsorption process of\npolarizable atoms and molecules."
    },
    {
        "anchor": "Effective anisotropy due to the surface of magnetic nanoparticles: Analytical solution has been found for the second-order effective anisotropy\nof magnetic nanoparticles of a cubic shape due to the surface anisotropy (SA)\nof the N\\'eel type. Similarly to the spherical particles, for the simple cubic\nlattice the grand-diagonal directions $\\left(\\pm1,\\pm1,\\pm1\\right)$ are favored\nby the effective cubic anisotropy but the effect is twice as strong. Uniaxial\ncore anisotropy and applied magnetic field cause screening of perturbations\nfrom the surface at the distance of the domain-wall width and reduce the effect\nof SA near the energy minima. However, screening disappears near the uniaxial\nenergy barrier, and the uniform barrier state of larger particles may become\nunstable. For these effects the analytical solution is obtained as well, and\nthe limits of the additive formula with the uniaxial and effective cubic\nanisotropies for the particle are established. Thermally-activated\nmagnetization-switching rates have been computed by the pulse-noise technique\nfor the stochastic Landau-Lifshitz equation for a system of spins.",
        "positive": "Scattering of two-dimensional Dirac fermions on gate-defined oscillating\n  quantum dots: Within an effective Dirac-Weyl theory we solve the scattering problem for\nmassless chiral fermions impinging on a cylindrical time-dependent potential\nbarrier. The set-up we consider can be used to model the electron propagation\nin a monolayer of graphene with harmonically driven quantum dots. For static\nsmall-sized quantum dots scattering resonances enable particle confinement and\ninterference effects may switch forward scattering on and off. An oscillating\ndot may cause inelastic scattering by excitation of states with energies\nshifted by integer multiples of the oscillation frequency, which significantly\nmodifies the scattering characteristics of static dots. Exemplarily the\nscattering efficiency of a potential barrier with zero bias remains finite in\nthe limit of low particle energies and small potential amplitudes. For an\noscillating quantum dot with finite bias, the partial wave resonances at higher\nenergies are smeared out for small frequencies or large oscillation amplitudes,\nthereby dissolving the quasi-bound states at the quantum dot."
    },
    {
        "anchor": "Quantized conductance at the Majorana phase transition in a disordered\n  superconducting wire: Superconducting wires without time-reversal and spin-rotation symmetries can\nbe driven into a topological phase that supports Majorana bound states. Direct\ndetection of these zero-energy states is complicated by the proliferation of\nlow-lying excitations in a disordered multi-mode wire. We show that the phase\ntransition itself is signaled by a quantized thermal conductance and electrical\nshot noise power, irrespective of the degree of disorder. In a ring geometry,\nthe phase transition is signaled by a period doubling of the magnetoconductance\noscillations. These signatures directly follow from the identification of the\nsign of the determinant of the reflection matrix as a topological quantum\nnumber.",
        "positive": "Two-subband quantum Hall effect in parabolic quantum wells: The low-temperature magnetoresistance of parabolic quantum wells displays\npronounced minima between integer filling factors. Concomitantly the Hall\neffect exhibits overshoots and plateau-like features next to well-defined\nordinary quantum Hall plateaus. These effects set in with the occupation of the\nsecond subband. We discuss our observations in the context of single-particle\nLandau fan charts of a two-subband system empirically extended by a density\ndependent subband separation and an enhanced spin-splitting g*."
    },
    {
        "anchor": "Band Connectivity for Topological Quantum Chemistry: Band Structures As\n  A Graph Theory Problem: The conventional theory of solids is well suited to describing band\nstructures locally near isolated points in momentum space, but struggles to\ncapture the full, global picture necessary for understanding topological\nphenomena. In part of a recent paper [B. Bradlyn et al., Nature 547, 298\n(2017)], we have introduced the way to overcome this difficulty by formulating\nthe problem of sewing together many disconnected local \"k-dot-p\" band\nstructures across the Brillouin zone in terms of graph theory. In the current\nmanuscript we give the details of our full theoretical construction. We show\nthat crystal symmetries strongly constrain the allowed connectivities of energy\nbands, and we employ graph-theoretic techniques such as graph connectivity to\nenumerate all the solutions to these constraints. The tools of graph theory\nallow us to identify disconnected groups of bands in these solutions, and so\nidentify topologically distinct insulating phases.",
        "positive": "An Analytic Description of Light Emission in Sonoluminescence: Light emission in sonoluminescence is shown to be a lasing process with a\nwide gain bandwidth. Population inversion of the gas molecules inside the\nbubble is achieved by hydrodynamical pumping. Analytic expressions are derived\nfor the sonoluminescence pulse shape, pulse width, and their codependence on\nthe spectrum and intensity in physically relevant regimes. A detailed\ncomparison with experiments(R. Hiller et al., Phys. Rev. Lett. 80, 1090 (1998);\nM.J. Moran et al., Phys. Rev. Lett. 80}, 4987 (1998); R. Pecha et al., Phys.\nRev. Lett. 81, 717 (1998)) suggests excellent agreement."
    },
    {
        "anchor": "High temperature magnetism and microstructure of semiconducting\n  ferromagnetic alloy (GaSb)$_{1-x}$(MnSb)$_{x}$: We have studied the properties of relatively thick (about 120 nm) magnetic\ncomposite films grown by pulsed laser deposition method using\n(GaSb)$_{0.59}$(MnSb)$_{0.41}$ eutectic compound as a target for sputtering.\nFor the studied films we have observed ferromagnetism and anomalous Hall effect\nabove the room temperature, it manifests the presence of spin-polarized\ncarriers. Electron microscopy, atomic and magnetic force microscopy results\nsuggests that films under study have homogenous columnar structure in the bulk\nwhile MnSb inclusions accumulate near it's surface. This is in good agreement\nwith high mobility values of charge carriers. Based on our data we conclude\nthat room temperature magnetic and magnetotransport properties of the films are\ndefined by MnSb inclusions.",
        "positive": "Electronic and Optical properties of transition metal dichalcogenides\n  under symmetric and asymmetric field-effect doping: Doping via electrostatic gating is a powerful and widely used technique to\ntune the electron densities in layered materials. The microscopic details of\nhow these setups affect the layered material are, however, subtle and call for\ncareful theoretical treatments. Using semiconducting monolayers of transition\nmetal dichalcogenides (TMDs) as prototypical systems affected by electrostatic\ngating, we show that the electronic and optical properties change indeed\ndramatically when the gating geometry is properly taken into account. This\neffect is implemented by a self-consistent calculation of the Coulomb\ninteraction between the charges in different sub-layers within the\ntight-binding approximation. Thereby we consider both, single- and double-sided\ngating. Our results show that, at low doping levels of $10^{13}$ cm$^{-2}$, the\nelectronic bands of monolayer TMDs shift rigidly for both types of gating, and\nsubsequently undergo a Lifshitz transition. When approaching the doping level\nof $10^{14}$ cm$^{-2}$, the band structure changes dramatically, especially in\nthe case of single-sided gating where we find that monolayer \\ce{MoS2} and\n\\ce{WS2} become indirect gap semiconductors. The optical conductivities\ncalculated within linear response theory also show clear signatures of these\ndoping-induced band structure renormalizations. Our numerical results based on\nlight-weighted tight-binding models indicate the importance of electronic\nscreening in doped layered structures, and pave the way for further\nunderstanding gated super-lattice structures formed by mutlilayers with\nextended Moir\\'{e} pattern."
    },
    {
        "anchor": "Diffusive-hydrodynamic transition in the anomalous Hall effect: We have developed a theory of the anomalous Hall effect in two-dimensional\nelectron gas in the case where the time of electron-electron collisions is much\nsmaller than the transport relaxation time. The transition between the\ndiffusion transport regime, when the momentum relaxation length of electrons is\nmuch smaller than the channel width, and the hydrodynamic regime, when the\nmomentum relaxation length exceeds the channel width, has been traced. The\ncontributions of the anomalous velocity, wave packet shifts, and asymmetric\nscattering to the anomalous Hall field and voltage have been calculated. It has\nbeen shown that the anomalous Hall voltage caused by the asymmetric scattering\ncan have a nontrivial coordinate dependence and change its sign depending on\nthe specific scattering mechanism.",
        "positive": "Non-Equilibrium Charge Dynamics in Majorana-Josephson Devices: We investigate the impact of introducing Majorana bound states, formed by a\nproximitized semiconducting nanowire in the topological regime, into a current\nbiased capacitive Josephson junction, thereby adding delocalized states below\nthe superconducting gap. We find that this qualitatively changes the charge\ndynamics of the system, diminishing the role of Bloch oscillations and causing\nsingle-particle tunnelling effects to dominate. We fully characterize the\nresulting charge dynamics and the associated voltage and current signals. Our\nwork reveals a rich landscape of behaviours in both the static and time-varying\ndriving modes. This can be directly attributed to the presence of Majorana\nbound states, which serve as a pathway for charge transport and enable\nnon-equilibrium excitations of the Majorana-Josephson device."
    },
    {
        "anchor": "Localization of magnon modes in a curved magnetic nanowire: Spin waves in magnetic nanowires can be bound by a local bending of the wire.\nThe eigenfrequency of a truly local magnon mode is determined by the curvature:\na general analytical expression is established for any infinitesimally weak\nlocalized curvature of the wire. The interaction of the local mode with spin\nwaves, propagating through the bend, results in scattering features, which is\nwell confirmed by spin-lattice simulations.",
        "positive": "Non-diffusive spin dynamics in a two-dimensional electron gas: We describe measurements of spin dynamics in the two-dimensional electron gas\nin GaAs/GaAlAs quantum wells. Optical techniques, including transient\nspin-grating spectroscopy, are used to probe the relaxation rates of spin\npolarization waves in the wavevector range from zero to $6\\times 10^4$\ncm$^{-1}$. We find that the spin polarization lifetime is maximal at nonzero\nwavevector, in contrast with expectation based on ordinary spin diffusion, but\nin quantitative agreement with recent theories that treat diffusion in the\npresence of spin-orbit coupling."
    },
    {
        "anchor": "Real Hopf Insulator: Establishing the fundamental relation between the homotopy invariants and the\nband topology of Hamiltonians has played a critical role in the recent\ndevelopment of topological phase research. In this work, we establish the\nhomotopy invariant and the related band topology of three-dimensional (3D)\nreal-valued Hamiltonians with two occupied and two unoccupied bands. Such a\nreal Hamiltonian generally appears in $\\mathcal{PT}$ symmetric spinless fermion\nsystems where $\\mathcal{P}$ and $\\mathcal{T}$ indicate the inversion and\ntime-reversal symmetries, respectively. We show that the 3D band topology of\nthe system is characterized by two independent Hopf invariants when the\nlower-dimensional band topology is trivial. Thus, the corresponding 3D band\ninsulator with nonzero Hopf invariants can be called a real Hopf insulator\n(RHI). In sharp contrast to all the other topological insulators discovered up\nto now, the topological invariants of RHI can be defined only when the fixed\nnumber of both the occupied and unoccupied states are simultaneously\nconsidered. Thus, the RHI belongs to the category of delicate topological\ninsulators proposed recently. We show that finite-size systems with slab\ngeometry support surface states with nonzero Chern numbers in a\n$\\mathcal{PT}$-symmetric manner independent of the Fermi level position, and\nestablish the bulk-boundary correspondence. We also discuss the bulk-boundary\ncorrespondence of rotation symmetric RHIs using the returning Thouless pump.",
        "positive": "An `all-carbon' molecular device: We have performed parameter-free calculations of electron transport across a\ncarbon molecular junction consisting of a C$_{60}$ molecule sandwiched between\ntwo semi-infinite metallic carbon nanotubes. It is shown that the Landauer\nconductance of this carbon hybrid system can be tuned within orders of\nmagnitude not only by varying the tube-C$_{60}$ distance, but more importantly\nat fixed distances by i) changing the orientation of the Buckminsterfullerene\nor ii) rotating one of the tubes around its cylinder axis. Furthermore, it is\nexplicitely shown that structural relaxation determines qualitatively the\ntransmission spectrum of such devices."
    },
    {
        "anchor": "Shot noise in Graphene with long range Coulomb interaction and the local\n  Fermi distribution: We calculate the shot noise power in ballistic graphene using the kinetic\nequation approach based on the Keldysh technique. We find that the local energy\ndistribution function obeys Poisson's equation, indicating a mapping into a\ndiffusive metal system. We derive the conductance and noise including the long\nrange Coulomb interaction to first order. We find that the shot noise increases\ndue to interaction, leading to a frequency dependence. Furthermore, we find\nthat the Fano factor at degeneracy is 1/3, the same as without the Coulomb\ninteraction.",
        "positive": "A covering property of Hofstadter's butterfly: Based on a thorough numerical analysis of the spectrum of Harper's operator,\nwhich describes, e.g., an electron on a two-dimensional lattice subjected to a\nmagnetic field perpendicular to the lattice plane, we make the following\nconjecture: For any value of the incommensurability parameter sigma of the\noperator its spectrum can be covered by the bands of the spectrum for every\nrational approximant of sigma after stretching them by factors with a common\nupper bound. We show that this conjecture has the following important\nconsequences: For all irrational values of sigma the spectrum is (i) a zero\nmeasure Cantor set and has (ii) a Hausdorff dimension less or equal to 1/2. We\npropose that our numerical approach may be a guide in finding a rigorous proof\nof these results."
    },
    {
        "anchor": "Biexcitons in Highly Excited CdSe Nanoplatelets: We present the phase diagram of free charges (electrons and holes), excitons,\nand biexcitons in highly excited CdSe nanoplatelets that predicts a crossover\nto a biexciton-dominated region at easily attainable low temperatures or high\nphotoexcitation densities. Our findings extend previous work describing only\nfree charges and excitons by introducing biexcitons into the equation of state,\nwhile keeping the exciton and biexciton binding energies constant in view of\nthe relatively low density of free charges in this material. Our predictions\nare experimentally testable in the near future and offer the prospect of\ncreating a quantum degenerate, and possibly even superfluid, biexciton gas.\nFurthermore, we also provide simple expressions giving analytical insight into\nthe regimes of photoexcitation densities and temperatures in which excitons and\nbiexcitons dominate the response of the nanoplatelets.",
        "positive": "Quantum Dot in 2D Topological Insulator: The Two-channel Kondo Fixed\n  Point: In this work, a quantum dot couples to two helical edge states of a 2D\ntopological insulator through weak tunnelings is studied. We show that if the\nelectron interactions on the edge states are repulsive, with Luttinger liquid\nparameter $ K < 1 $, the system flows to a stable two-channel fixed point at\nlow temperatures. This is in contrast to the case of a quantum dot couples to\ntwo Luttinger liquid leads. In the latter case, a strong electron-electron\nrepulsion is needed, with $ K<1/2 $, to reach the two-channel fixed point. This\ntwo-channel fixed point is described by a boundary Sine-Gordon Hamiltonian with\na $K$ dependent boundary term. The impurity entropy at zero temperature is\nshown to be $ \\ln\\sqrt{2K} $. The impurity specific heat is $C \\propto\nT^{\\frac{2}{K}-2}$ when $ 2/3 < K < 1 $, and $ C \\propto T$ when $ K<2/3$. We\nalso show that the linear conductance across the two helical edges has\nnon-trivial temperature dependence as a result of the renormalization group\nflow."
    },
    {
        "anchor": "Ballistic quantum transport through Ge/Si core/shell nanowires: We study ballistic hole transport through Ge/Si core/shell nanowires at low\ntemperatures. We observe Fabry-P$\\acute{e}$rot interference patterns as well as\nconductance plateaus at integer multiples of 2e$^2$/h at zero magnetic field.\nMagnetic field evolution of these plateaus reveals large effective\nLand$\\acute{e}$ g-factors. Ballistic effects are observed in nanowires with\nsilicon shell thicknesses of 1 - 3 nm, but not in bare germanium wires. These\nfindings inform the future development of spin and topological quantum devices\nwhich rely on ballistic subband-resolved transport.",
        "positive": "Optical switching of resonance fluorescence from a single germanium\n  vacancy color center in diamond: Scalable quantum photonic networks require coherent excitation of quantum\nemitters. However, many solid-state systems can undergo a transition to a dark\nshelving state that inhibits the fluorescence. Here we demonstrate that a\ncontrolled gating using a weak non-resonant laser, the resonant excitation can\nbe recovered and amplified for single germanium vacancies (GeVs). Employing the\ngated resonance excitation, we achieve optically stable resonance fluorescence\nof GeV centers. Our results are pivotal for the deployment of diamond color\ncenters as reliable building blocks for scalable solid state quantum networks."
    },
    {
        "anchor": "Two-particle entanglement in capacitively coupled Mach-Zehnder\n  interferometers: We propose and analyze a mesoscopic device producing on-demand entangled\npairs of electrons. The system consists of two capacitively coupled\nMach-Zehnder interferometers implemented in a quantum Hall structure. A pair of\nelectron wave-packets is injected into the chiral edge states of two (of the\nfour) incoming arms; scattering on the incoming interferometers splits the\nwave-packets into four components of which two interact. The resulting\ninteraction phase associated with this component leads to the entanglement of\nthe state; the latter is scattered at the outgoing beam splitter and analyzed\nin a Bell violation test measuring the presence of particles in the four\noutgoing leads. We study the two-particle case and determine the conditions to\nreach and observe full entanglement. We extend our two-particle analysis to\ninclude the underlying Fermi seas in the quantum Hall device; the change in\nshape of the wave-function, the generation of electron-hole pairs in the\ninteraction regime, and a time delay between the pulses all reduce the degree\nof visible entanglement and the violation of the Bell inequality, effects which\nwe analyze quantitatively. We determine the device settings optimizing the\nentanglement and the Bell test and find that violation is still possible in the\npresence of the Fermi seas, with a maximal Bell parameter reaching ${\\cal B} =\n2.18 > 2$ in our setup.",
        "positive": "Anisotropic Keldysh interaction: We generalize the classic calculations by Rytova and Keldysh of screened\nCoulomb interaction in semiconductor thin films to systems with anisotropic\npermittivity tensor. Explicit asymptotic expressions for electrostatic\npotential energy of interaction in the weakly anisotropic case are found in\nclosed analytical form. The case of strong in-plane anisotropy, however,\nrequires evaluation of the inverse Fourier transform of $1/(k+Ak_x^2+Bk_y^2)$,\nwhich, at present, remains unresolved."
    },
    {
        "anchor": "Transport in chaotic quantum dots: effects of spatial symmetries which\n  interchange the leads: We investigate the effect of spatial symmetries on phase coherent electronic\ntransport through chaotic quantum dots. For systems which have a spatial\nsymmetry that interchanges the source and drain leads, we find in the framework\nof random matrix theory that the density of the transmission eigenvalues is\nindepedent of the number of channels N in the leads. As a consequence, the weak\nlocalization correction to the conductance vanishes in these systems, and the\nshot noise suppression factor F is independent of N. We confirm this prediction\nby means of numerical calculations for stadium billiards with various lead\ngeometries. These calculations also uncover transport signatures of partially\npreserved symmetries.",
        "positive": "Slow relaxations of magnetoresistance in AlGaAs-GaAs quantum well\n  structures quenched in a magnetic field: We observed a slow relaxation of magnetoresistance in response to applied\nmagnetic field in selectively doped p-GaAs-AlGaAs structures with partially\nfilled upper Hubbard band. We have paid a special attention to exclude the\neffects related to temperature fluctuations. Though this effect is important,\nwe have found that the general features of slow relaxation still persist. This\nbehavior is interpreted as related to the properties of the Coulomb glass\nformed by charged centers with account of spin correlations, which are\nsensitive to an external magnetic field. Variation of the magnetic field\nchanges numbers of impurity complexes of different types. As a result, it\neffects the shape and depth of the polaron gap formed at the states belonging\nto the percolation cluster responsible for the conductance. The suggested model\nexplains both the qualitative behavior and the order of magnitude of the slowly\nrelaxing magnetoresistance."
    },
    {
        "anchor": "Plenty of motion at the bottom: Atomically thin liquid gold membrane: The discovery of graphene some ten years ago was the first proof of a\nfree-standing two-dimensional (2D) solid phase. Here, using quantum molecular\ndynamics simulations of nanoscale gold patches suspended in graphene pores, we\npredict the existence of an atomically thin, free-standing 2D liquid phase. The\nliquid phase, enabled by the exceptional planar stability of gold due to\nrelativistic effects, demonstrates extreme fluxionality of metal nanostructures\nand opens possibilities for a variety of nanoscale phenomena.",
        "positive": "Decoupling of the many-body effects from the electron mass in GaAs by\n  means of reduced dimensionality: Determining the (bare) electron mass $m_0$ in crystals is often hindered by\nmany-body effects since Fermi-liquid physics renormalises the band mass, making\nthe observed effective mass $m^*$ depend on density. Here, we use a\none-dimensional (1D) geometry to amplify the effect of interactions, forcing\nthe electrons to form a nonlinear Luttinger liquid with separate holon and\nspinon bands, therefore separating the interaction effects from $m_0$.\nMeasuring the spectral function of gated quantum wires formed in GaAs by means\nof magnetotunnelling spectroscopy and interpreting them using the 1D\nFermi-Hubbard model, we obtain $m_0=(0.0525\\pm0.0015)m_\\textrm{e}$ in this\nmaterial, where $m_\\textrm{e}$ is the free-electron mass. By varying the\ndensity in the wires, we change the interaction parameter $r_\\textrm{s}$ in the\nrange from $\\sim$1-4 and show that $m_0$ remains constant. The determined value\nof $m_0$ is $\\sim 22$% lighter than observed in GaAs in geometries of higher\ndimensionality $D$ ($D>1$), consistent with the quasi-particle picture of a\nFermi liquid that makes electrons heavier in the presence of interactions."
    },
    {
        "anchor": "A physically unclonable function using NV diamond magnetometry and\n  micromagnet arrays: A physically unclonable function (PUF) is an embedded hardware security\nmeasure that provides protection against counterfeiting. Here we present our\nwork on using an array of randomly-magnetized micron-sized ferromagnetic bars\n(micromagnets) as a PUF. We employ a 4 $\\mu$m thick surface layer of\nnitrogen-vacancy (NV) centers in diamond to image the magnetic fields from each\nmicromagnet in the array, after which we extract the magnetic polarity of each\nmicromagnet using image analysis techniques. After evaluating the randomness of\nthe micromagnet array PUF and the sensitivity of the NV readout, we conclude by\ndiscussing the possible future enhancements for improved security and magnetic\nreadout.",
        "positive": "The focusing of electron flow in a bipolar Graphene ribbon with\n  different chiralities: The focusing of electron flow in a symmetric p-n junction (PNJ) of graphene\nribbon with different chiralities is studied. Considering the PNJ with the\nsharp interface, in a armchair ribbon, the electron flow emitting from $(-L,0)$\nin n-region can always be focused perfectly at $(L,0)$ in p-region in the whole\nDirac fermion regime, i.e. in whole regime $E_0<t$ where $E_0$ is the distance\nbetween Dirac-point energy and Fermi energy and $t$ is the nearest hopping\nenergy. For the bipolar ribbon with zigzag edge, however, the incoming electron\nflow in n-region is perfectly converged in p-region only in a very low energy\nregime with $E_0<0.05t$. Moreover, for a smooth PNJ, electrons are\nbackscattered near PNJ, which weakens the focusing effect. But the focusing\npattern still remains the same as that of the sharp PNJ. In addition, quantum\noscillation in charge density occurs due to the interference between forward\nand backward scattering. Finally, in the presence of weak perpendicular\nmagnetic field, charge carriers are deflected in opposite directions in the\np-region and n-region. As a result, the focusing effect is smeared. The lower\nenergy $E_0$, the easier the focusing effect is destroyed. For the high energy\n$E_0$ (e.g. $E_0=0.9t$), however, the focusing effect can still survive in a\nmoderate magnetic field on order of one Tesla."
    },
    {
        "anchor": "Coherent Phonons-Driven Hot Carrier Effect in a Superlattice Solar Cell: Carrier thermalization in a superlattice solar cell made of polar\nsemiconductors is studied theoretically by considering a minimal model where\nelectron-phonon scattering is the principal channel of carrier energy loss.\nImportantly, the effect of an intrinsic quantum mechanical property; the phonon\ncoherence, on carrier thermalization is investigated, within semiclassical\npicture in terms of phonon wave packet. It turns out that coherent longitudinal\noptical (LO) phonons weaken the effective electron-phonon coupling, thus\nsupposedly lowering the carrier energy loss rate in solar cell. The resulting\nthermalization power is indeed significantly reduced by the coherent phonons,\nresulting in enhanced hot carrier effect, particularly for thin enough well\nlayer where carrier confinement is also strong. A recent experiment on\nsuperlattice solar cell prototype is shown to manifest the coherent\nphonons-driven phenomenon. Our results demonstrate the practical implications\nof the fundamental quantum coherence property of phonons in semiconductors for\nimproving superlattice solar cell performance, via hot carrier effect.",
        "positive": "Current facilitation by plasmon resonances between parallel wires of\n  finite length: The current voltage (IV) characteristics for perpendicular transport through\ntwo sequentially coupled wires of finite length is calculated analytically. The\ntransport within a Coulomb blockade step is assisted by plasmon resonances that\nappear as steps in the IV characteristics with positions and heights depending\non inter- and intrawire interactions. In particular, due to the interwire\ninteractions, the peak positions shift to lower voltages in comparison to the\nnoninteracting wires which reflects the facilitation of current by\ninteractions. The interwire interactions are also found to enhance the\nthermally activated current."
    },
    {
        "anchor": "Second harmonic generation from metallic arrays of rectangular holes: The generation process of second harmonic (SH) radiation from holes\nperiodically arranged on a metal surface is investigated. Three main modulating\nfactors affecting the optical response are identified: the near-field\ndistribution at the wavelength of the fundamental harmonic, how SH light\ncouples to the diffraction orders of the lattice, and its propagation\nproperties inside the holes. It is shown that light generated at the second\nharmonic can excite electromagnetic modes otherwise inaccessible in the linear\nregime under normal incidence illumination. It is demonstrated that the\nemission of SH radiation is only allowed along off-normal paths precisely due\nto that symmetry. Two different regimes are studied in the context of\nextraordinary optical transmission, where enhanced linear transmission either\noccurs through localized electromagnetic modes or is aided by surface plasmon\npolaritons (SPPs). While localized resonances in metallic hole arrays have been\npreviously investigated, the role played by SPPs in SH generation has not been\naddressed so far. In general, good agreement is found between our calculations\n(based on the finite difference time domain method) and the experimental\nresults on localized resonances, even though no free fitting parameters were\nused in describing the materials. It is found that SH emission is strongly\nmodulated by enhanced fields at the fundamental wavelength (either localized or\nsurface plasmon modes) on the glass metal interface. This is so in the\ntransmission side but also in reflection, where emission can only be explained\nby an efficient tunneling of SH photons through the holes from the output to\nthe input side. Finally, the existence of a dark SPP at the fundamental field\nis identified through a noninvasive method for the first time, by analyzing the\nefficiency and far-field pattern distribution in transmission at the second\nharmonic.",
        "positive": "One-dimensional ZnO exciton polaritons with negligible thermal\n  broadening at room temperature: Phonon damping is the main source of pure dephasing in the solid state,\nlimiting many fundamental quantum effects to low temperature observations. Here\nwe show how excitons in semiconductors can be totally decoupled from the phonon\nbath, even at room temperature, thanks to their strong interaction with\nphotons. To do so, we investigated ZnO microwires, a new semiconductor\nnanostructure made of large band-gap material where the light can be trapped\nand guided into whispering gallery modes. In this system, the very large\ncoupling regime between exciton and photon results in unusual exciton-polariton\nof one-dimensional character and Rabi splitting as large as 300meV. We find\nthat polariton modes of excitonic fraction up to 75% exhibit no thermal\nbroadening up to room temperature. We show that this remarkable behavior is due\nto the very large Rabi splitting as compared to the LO phonon energy."
    },
    {
        "anchor": "Surface and Bulk Effects of K in Cu$_{1-x}$K$_x$In$_{1-y}$Ga$_y$Se$_2$\n  Solar Cells: Two strategies for enhancing photovoltaic (PV) performance in chalcopyrite\nsolar cells were investigated: Cu1-xKxIn1-yGaySe2 absorbers with low K content\n(K/(K+Cu), or x ~ 0.07) distributed throughout the bulk, and CuIn1-yGaySe2\nabsorbers with KIn1-yGaySe2 grown on their surfaces. For the Ga-free case,\nincreased temperature improved PV performance in the KInSe2 surface absorbers,\nbut not in the bulk x ~ 0.07 absorbers. Growth temperature also increased\nKInSe2 phase fraction, relative to Cu1-xKxInSe2 alloys-evidence that surface\nKInSe2 improved performance more than bulk KInSe2. Surface KIn1-yGaySe2 and\nbulk x ~ 0.07 Cu1-xKxIn1-yGaySe2 films with Ga/(Ga+In), or y of 0.3 and 0.5\nalso had improved efficiency, open-circuit voltage (VOC), and fill factor (FF),\nrelative to CuIn1-yGaySe2 baselines. On the other hand, y ~ 1 absorbers did not\nbenefit from K introduction. Similar to Cu1-xKxInSe2, the formation of\nCu1-xKxGaSe2 alloys was favored at low temperatures and high substrate Na\ncontent, relative to the formation of mixed-phase CuGaSe2 + KGaSe2.\nKIn1-yGaySe2 alloys were grown for the first time, as evidenced by X-ray\ndiffraction and ultraviolet/visible spectroscopy. For all Ga/(Ga+In)\ncompositions, the surface KIn1-yGaySe2 absorbers had superior PV performance in\nbuffered and buffer-free devices. However, the bulk x ~ 0.07 absorbers only\noutperformed the baselines in buffered devices. The data demonstrate that\nKIn1-yGaySe2 passivates the surface of CuIn1-yGaySe2 to increase efficiency,\nVOC, and FF, while bulk Cu1-xKxIn1-yGaySe2 absorbers with x ~ 0.07 enhance\nefficiency, VOC, and FF by some other mechanism.",
        "positive": "Overview: Brownian Motion and Dephasing due to Dynamical Disorder: The motion of a particle under the influence of a dynamical disorder is\ndescribed by the DLD model. One motivation is to understand the motion of an\nelectron inside a metal; Another is to understand quantal Brownian motion. The\noverview is based on a research report for 1996-1998."
    },
    {
        "anchor": "Evidence of ratchet effect in nanowires of a conducting polymer: Ratchet effect, observed in many systems starting from living organism to\nartificially designed device, is a manifestation of motion in asymmetric\npotential. Here we report results of a conductivity study of Polypyrrole\nnanowires, which have been prepared by a simple method to generate a variation\nof doping concentration along the length. This variation gives rise to an\nasymmetric potential profile that hinders the symmetry of the hopping process\nof charges and hence the value of measured resistance of these nanowires become\nsensitive to the direction of current flow. The asymmetry in resistance was\nfound to increase with decreasing nanowire diameter and increasing temperature.\nThe observed phenomena could be explained with the assumption that the spatial\nextension of localized state involved in hopping process reduces as the doping\nconcentration reduces along the length of the nanowires.",
        "positive": "Quantum interference and Klein tunneling in graphene heterojunctions: The observation of quantum conductance oscillations in mesoscopic systems has\ntraditionally required the confinement of the carriers to a phase space of\nreduced dimensionality. While electron optics such as lensing and focusing have\nbeen demonstrated experimentally, building a collimated electron interferometer\nin two unconfined dimensions has remained a challenge due to the difficulty of\ncreating electrostatic barriers that are sharp on the order of the electron\nwavelength. Here, we report the observation of conductance oscillations in\nextremely narrow graphene heterostructures where a resonant cavity is formed\nbetween two electrostatically created bipolar junctions. Analysis of the\noscillations confirms that p-n junctions have a collimating effect on\nballistically transmitted carriers. The phase shift observed in the conductance\nfringes at low magnetic fields is a signature of the perfect transmission of\ncarriers normally incident on the junctions and thus constitutes a direct\nexperimental observation of ``Klein Tunneling.''"
    },
    {
        "anchor": "Fast Reset and Suppressing Spontaneous Emission of a Superconducting\n  Qubit: Spontaneous emission through a coupled cavity can be a significant decay\nchannel for qubits in circuit quantum electrodynamics. We present a circuit\ndesign that effectively eliminates spontaneous emission due to the Purcell\neffect while maintaining strong coupling to a low-Q cavity. Excellent agreement\nover a wide range in frequency is found between measured qubit relaxation times\nand the predictions of a circuit model. Using fast (nanosecond time-scale) flux\nbiasing of the qubit, we demonstrate in situ control of qubit lifetime over a\nfactor of 50. We realize qubit reset with 99.9% fidelity in 120 ns.",
        "positive": "Non-local polarization feedback in a fractional quantum Hall ferromagnet: In a quantum Hall ferromagnet, the spin polarization of the two-dimensional\nelectron system can be dynamically transferred to nuclear spins in its vicinity\nthrough the hyperfine interaction. The resulting nuclear field typically acts\nback locally, modifying the local electronic Zeeman energy. Here we report a\nnon-local effect arising from the interplay between nuclear polarization and\nthe spatial structure of electronic domains in a $\\nu=2/3$ fractional quantum\nHall state. In our experiments, we use a quantum point contact to locally\ncontrol and probe the domain structure of different spin configurations\nemerging at the spin phase transition. Feedback between nuclear and electronic\ndegrees of freedom gives rise to memristive behavior, where electronic\ntransport through the quantum point contact depends on the history of current\nflow. We propose a model for this effect which suggests a novel route to\nstudying edge states in fractional quantum Hall systems and may account for\nso-far unexplained oscillatory electronic-transport features observed in\nprevious studies."
    },
    {
        "anchor": "Photoinduced electronic and spin properties of two-dimensional electron\n  gases with Rashba spin-orbit coupling under perpendicular magnetic fields: We theoretically investigate photoinduced phenomena induced by time-periodic\ndriving fields in two-dimensional electron gases under perpendicular magnetic\nfields with Rashba spin-orbit coupling. Using perturbation theory, we provide\nanalytical results for the Floquet-Landau energy spectrum appearing due to THz\nradiation. By employing the resulting photo-modulated states, we compute the\ndynamical evolution of the spin polarization function for an initially prepared\ncoherent state. We find that the interplay of the magnetic field, Rashba\nspin-orbit interaction and THz radiation can lead to inversion of the spin\npolarization. The dynamics also induces fractional revivals and non-trivial\nbeating patterns in the autocorrelation function due to interference of the\nphoto-modulated quantum states. We also calculate the transverse photo-assisted\nconductivity in the linear response regime using Kubo formalism and analyze the\nimpact of the radiation field and Rashba spin-orbit interaction. In the static\nlimit, we find that our results reduce to well-known expressions of the\nconductivity in non-relativistic and quasi-relativistic (topological insulator\nsurfaces) two-dimensional electron gas thoroughly described in the literature.\nWe discuss the possible experimental detection of our theoretical prediction\nand their relevance for spin-orbit physics at high magnetic fields.",
        "positive": "Step-like dependence of memory function on pulse width in spintronics\n  reservoir computing: Physical reservoir computing is a type of recurrent neural network that\napplies the dynamical response from physical systems to information processing.\nHowever, the relation between computation performance and physical\nparameters/phenomena still remains unclear. This study reports our progress\nregarding the role of current-dependent magnetic damping in the computational\nperformance of reservoir computing. The current-dependent relaxation dynamics\nof a magnetic vortex core results in an asymmetric memory function with respect\nto binary inputs. A fast relaxation caused by a large input leads to a fast\nfading of the input memory, whereas a slow relaxation by a small input enables\nthe reservoir to keep the input memory for a relatively long time. As a result,\na step-like dependence is found for the short-term memory and parity-check\ncapacities on the pulse width of input data, where the capacities remain at 1.5\nfor a certain range of the pulse width, and drop to 1.0 for a long pulse-width\nlimit. Both analytical and numerical analyses clarify that the step-like\nbehavior can be attributed to the current-dependent relaxation time of the\nvortex core to a limit-cycle state. }"
    },
    {
        "anchor": "Decay of Rabi oscillations induced by magnetic dipole interactions in\n  diluted paramagnetic solids: Decay of Rabi oscillations of equivalent spins diluted in diamagnetic solid\nmatrix and coupled by magnetic dipole interactions is studied. It is shown that\nthese interactions result in random shifts of spin transient nutation\nfrequencies and thus lead to the decay of the transient signal. Averaging over\nrandom spatial distribution of spins within the solid and over their spectral\npositions within magnetic resonance line, we obtain analytical expressions for\nthe decay of Rabi oscillations. The rate of the decay in the case when the\nhalf-width of magnetic resonance line exceeds Rabi frequency is found to depend\non the intensity of resonant microwave field and on the spin concentration. The\nresults are compared with the literature data for E1' centers in glassy silica\nand [AlO4] centers in quartz.",
        "positive": "Neutral magic-angle bilayer graphene: Condon instability and chiral\n  resonances: We discuss the full optical response of twisted bilayer graphene at the\nneutrality point close to the magic angle within the continuum model (CM).\nFirstly, we identify three different channels consistent with the underlying\n$D_3$ symmetry, yielding the total, magnetic, and chiral response. Secondly, we\nnumerically calculate the full optical response in the immediate vicinity of\nthe magic angle $\\theta_m$ which provides a direct mapping of the CM onto an\neffective two-band model. We, further, show that the ground-state of the CM in\nthe immediate vicinity of $\\theta_m$ is unstable towards transverse current\nfluctuations, a so-called Condon instability. Thirdly, due to the large\ncounterflow, the acoustic plasmonic excitations with typical wave numbers have\nlarger energies than the optical ones and their energy density may be largely\nenhanced at certain frequencies which we denominate as {\\it chiral resonances}.\nFinally, we discuss symmetry relations for the optical response and their\nconsequences for the chiral response."
    },
    {
        "anchor": "Manipulation of Exciton Dynamics in Single-Layer WSe2 Using a Toroidal\n  Dielectric Metasurface: Recent advances in emerging atomically thin transition metal dichalcogenide\nsemiconductors with strong light-matter interactions and tunable optical\nproperties provide novel approaches for realizing new material functionalities.\nCoupling two-dimensional semiconductors with all-dielectric resonant\nnanostructures represents an especially attractive opportunity for manipulating\noptical properties in both the near-field and far-field regimes. Here, by\nintegrating single-layer WSe2 and titanium oxide (TiO2) dielectric metasurfaces\nwith toroidal resonances, we realized robust exciton emission enhancement over\none order of magnitude at both room and low temperatures. Furthermore, we could\ncontrol exciton dynamics and annihilation by using temperature to tailor the\nspectral overlap of excitonic and toroidal resonances, allowing us to\nselectively enhance the Purcell effect. Our results provide rich physical\ninsight into the strong light-matter interactions in single-layer TMDs coupled\nwith toroidal dielectric metasurfaces, with important implications for\noptoelectronics and photonics applications.",
        "positive": "Polaron relaxation in a quantum dot due to anharmonic coupling within a\n  mean-field approach: We study the electronic relaxation in a quantum dot within the polaron\napproach, by focusing on the {\\it reversible} anharmonic decay of longitudinal\noptical (LO) phonons forming the polaron into longitudinal acoustic (LA)\nphonons. The coherent coupling between the LO and LA phonons is treated within\na mean-field approach. We derive a temperature-dependent inter-level coupling\nparameter, related to the Gr\\\"uneisen parameter and the thermal expansion\ncoefficient, that characterizes an effective decay channel for the electronic\n(or excitonic) states. Within this theory, we obtain a characteristic\nanharmonic decay time of 1ns, 2-3 orders of magnitude longer than previous\npredictions based on the Fermi's Golden Rule. We suggest that coherent\nrelaxation due to carrier-carrier interaction is an efficient alternative to\nthe (too slow) polaron decay."
    },
    {
        "anchor": "Leakage radiation microscopy of surface plasmons launched by a\n  nanodiamond-based tip: Leakage-radiation microscopy of a thin gold film demonstrates the ability of\nan ensemble of fluorescent diamond nanoparticles attached onto the apex of an\noptical tip to serve as an efficient near-field surface-plasmon polariton\nlauncher. The implementation of the nanodiamond-based tip in a near-field\nscanning optical microscope will allow for an accurate control on the launching\nposition, thereby opening the way to scanning plasmonics.",
        "positive": "Resonant transmission of normal electrons through Andreev states in\n  ferromagnets: Giant oscillations of the conductance of a superconductor - ferromagnet -\nsuperconductor Andreev interferometer are predicted. The effect is due to the\nresonant transmission of normal electrons through Andreev levels when the\nvoltage $V$ applied to the ferromagnet is close to $2h_0/e$ ($h_0$ is the\nspin-dependant part of the electron energy). The effect of bias voltage and\nphase difference between the superconductors on the current and the\ndifferential conductance is presented. These efects allow a direct spectroscopy\nof Andreev levels in the ferromagnet."
    },
    {
        "anchor": "Mean-field description of multicomponent exciton-polariton superfluids: This is a review of spin-dependent (polarization) properties of\nmulticomponent exciton-polariton condensates in conditions when\nquasi-equilibrium mean-field Gross-Pitaevskii description can be applied.\nMainly two-component (spin states $\\pm1$) polariton condensates are addressed,\nbut some properties of four-component exciton condensates, having both the\nbright (spin $\\pm1$) and the dark (spin $\\pm2$) components, are discussed.\nChange of polarization state of the condensate and phase transitions in applied\nZeeman field are described. The properties of fractional vortices are given, in\nparticular, I present recent results on the warping of the field around\nhalf-vortices in the presence of longitudinal-transverse splitting of bare\npolariton bands, and discuss the geometrical features of warped half-vortices\n(in the framework of the lemon, monstar, and star classification).",
        "positive": "Controlling the entropy of a single-molecule junction: Single molecules are nanoscale thermodynamic systems with few degrees of\nfreedom. Thus, the knowledge of their entropy can reveal the presence of\nmicroscopic electron transfer dynamics, that are difficult to observe\notherwise. Here, we apply thermocurrent spectroscopy to directly measure the\nentropy of a single free radical molecule in a magnetic field. Our results\nallow us to uncover the presence of a singlet to triplet transition in one of\nthe redox states of the molecule, not detected by conventional charge transport\nmeasurements. This highlights the power of thermoelectric measurements which\ncan be used to determine the difference in configurational entropy between the\nredox states of a nanoscale system involved in conductance without any prior\nassumptions about its structure or microscopic dynamics."
    },
    {
        "anchor": "Graphene Dirac fermions in one-dimensional inhomogeneous field profiles:\n  Transforming magnetic to electric field: We show that the low-energy electronic structure of graphene under a\none-dimensional inhomogeneous magnetic field can be mapped into that of\ngraphene under an electric field or vice versa. As a direct application of this\ntransformation, we find that the carrier velocity in graphene is isotropically\nreduced under magnetic fields periodic along one direction with zero average\nflux. This counterintuitive renormalization has its origin in the pseudospin\nnature of graphene electronic states and is robust against disorder. In\nmagnetic graphene superlattices with a finite average flux, the Landau level\nbandwidth at high fields exhibits an unconventional behavior of decreasing with\nincreasing strength of the average magnetic field due to the linear energy\ndispersion of graphene. As another application of our transformation relation,\nwe show that the transmission probabilities of an electron through a magnetic\nbarrier in graphene can directly be obtained from those through an\nelectrostatic barrier or vice versa.",
        "positive": "Topology of Disconnected Elementary Band Representations: Elementary band representations are the fundamental building blocks of atomic\nlimit band structures. They have the defining property that at partial filling\nthey cannot be both gapped and trivial. Here, we give two examples -- one each\nin a symmorphic and a non-symmorphic space group -- of elementary band\nrepresentations realized with an energy gap. In doing so, we explicitly\nconstruct a counterexample to a claim by Michel and Zak that single-valued\nelementary band representations in non-symmorphic space groups with\ntime-reversal symmetry are connected. For each example, we construct a\ntopological invariant to explicitly demonstrate that the valence bands are\nnon-trivial. We discover a new topological invariant: a movable but unremovable\nDirac cone in the \"Wilson Hamiltonian\" and a bent-Z2 index."
    },
    {
        "anchor": "Optical modes in oxide-apertured micropillar cavities: We present a detailed experimental characterization of the spectral and\nspatial structure of the confined optical modes for oxide-apertured micropillar\ncavities, showing good-quality Hermite-Gaussian profiles, easily mode-matched\nto external fields. We further derive a relation between the frequency\nsplitting of the transverse modes and the expected Purcell factor. Finally, we\ndescribe a technique to retrieve the profile of the confining refractive index\ndistribution from the spatial profiles of the modes.",
        "positive": "Helicity protected ultrahigh mobility Weyl fermions in NbP: Non-centrosymmetric transition metal monopnictides, including TaAs, TaP,\nNbAs, and NbP, are emergent topological Weyl semimetals (WSMs) hosting exotic\nrelativistic Weyl fermions. In this letter, we elucidate the physical origin of\nthe unprecedented charge carrier mobility of NbP, which can reach\n$1\\times10^{7}$ cm $^{2}$V$^{-1}$s$^{-1}$ at 1.5 K. Angle- and\ntemperature-dependent quantum oscillations, supported by density function\ntheory calculations, reveal that NbP has the coexistence of p- and n-type WSM\npockets in the $k_{z}$=1.16$\\pi$/c plane (W1-WSM) and in the $k_{z}$=0 plane\nnear the high symmetry points $\\Sigma$ (W2-WSM), respectively. Uniquely, each\nW2-WSM pocket forms a large dumbbell-shaped Fermi surface (FS) enclosing two\nneighboring Weyl nodes with the opposite chirality. The magneto-transport in\nNbP is dominated by these highly anisotropic W2-WSM pockets, in which Weyl\nfermions are well protected from defect backscattering by real spin\nconservation associated to the chiral nodes. However, with a minimal doping of\n$\\sim$1\\% Cr, the mobility of NbP is degraded by more than two order of\nmagnitude, due to the invalid of helicity protection to magnetic impurities.\nHelicity protected Weyl fermion transport is also manifested in chiral anomaly\ninduced negative magnetoresistance, controlled by the W1-WSM states. In the\nquantum regime below 10 K, the intervalley scattering time by impurities\nbecomes a large constant, producing the sharp and nearly identical conductivity\nenhancement at low magnetic field."
    },
    {
        "anchor": "Yu-Shiba-Rusinov multiplets and clusters of multiorbital adatoms in\n  superconducting substrates: Subgap Green's function approach: We discuss all the characteristics of Yu-Shiba-Rusinov states for clusters of\nimpurities with classical magnetic moments in a superconducting substrate with\ns-wave symmetry. We consider the effect of the multiorbital structure of the\nimpurities and the effect of the crystal field splitting. We solve the problem\nexactly and calculate the subgap Green's function, which has poles at the\nenergies of the Shiba states and defines the local density of states associated\nto their wave functions. For the case of impurities sufficiently separated, we\nderive an effective Hamiltonian to describe the hybridization mediated by the\nsubstrate. We analyze the main features of the spectrum and the spectral\ndensity of the subgap excitations for impurities in dimer configurations with\ndifferent relative orientations of the magnetic moments. We also illustrate how\nthe same formalism applies for the solution of a trimer with frustration in the\norientation of the magnetic moments.",
        "positive": "Phase-Coherent Transport through a Mesoscopic System: A New Probe of\n  Non-Fermi-Liquid Behavior: A novel chiral interferometer is proposed that allows for a direct\nmeasurement of the phase of the transmission coefficient for transport through\na variety of mesoscopic structures in a strong magnetic field. The effects of\nelectron-electron interaction on this phase is investigated with the use of\nfinite-size bosonization techniques combined with perturbation theory\nresummation. New non-Fermi-liquid phenomena are predicted in the FQHE regime\nthat may be used to distinguish experimentally between Luttinger and Fermi\nliquids."
    },
    {
        "anchor": "Effects of polariton squeezing on the emission of an atom embedded in a\n  microcavity: We are interested in the emission characteristics of an atom interacting with\nthe polaritonic excitations of a semiconductor or insulator embedded in a\none-mode cavity. Since polaritons inside of the cavity exhibit intrinsic\nsqueezing, we discuss how the squeezed polariton ground state modifies the\natomic emission and how an indirect evidence of polariton squeezing outside of\nhe cavity may be obtained.",
        "positive": "Hardware-aware $in \\ situ$ Boltzmann machine learning using stochastic\n  magnetic tunnel junctions: One of the big challenges of current electronics is the design and\nimplementation of hardware neural networks that perform fast and\nenergy-efficient machine learning. Spintronics is a promising catalyst for this\nfield with the capabilities of nanosecond operation and compatibility with\nexisting microelectronics. Considering large-scale, viable neuromorphic systems\nhowever, variability of device properties is a serious concern. In this paper,\nwe show an autonomously operating circuit that performs hardware-aware machine\nlearning utilizing probabilistic neurons built with stochastic magnetic tunnel\njunctions. We show that $in \\ situ$ learning of weights and biases in a\nBoltzmann machine can counter device-to-device variations and learn the\nprobability distribution of meaningful operations such as a full adder. This\nscalable autonomously operating learning circuit using spintronics-based\nneurons could be especially of interest for standalone artificial-intelligence\ndevices capable of fast and efficient learning at the edge."
    },
    {
        "anchor": "Narrowing of the flexural phonon spectral line in stressed crystalline\n  two-dimensional materials: We develop the microscopic theory for the attenuation of out-of-plane phonons\nin stressed flexible two-dimensional crystalline materials. We demonstrate that\nthe presence of nonzero tension strongly reduces the relative magnitude of the\nattenuation and, consequently, results in parametrical narrowing of the\nphononspectral line. We predict the specific power-law dependence of the\nspectral-line width on temperature and tension. We speculate that suppression\nof the phonon attenuation by nonzero tension might be responsible for high\nquality factors of mechanical nanoresonators based on flexural two-dimensional\nmaterials.",
        "positive": "Cotunneling and renormalization effects for the single-electron\n  transistor: We study electron transport through a small metallic island in the\nperturbative regime. Using a diagrammatic real-time technique, we calculate the\noccupation of the island as well as the conductance through the transistor at\narbitrary temperature and bias voltage in forth order in the tunneling matrix\nelements, a process referred to as cotunneling. Our formulation does not\nrequire the introduction of a cutoff. At resonance we find significant\nmodifications of previous theories and quantitative agreement with recent\nexperiments. We determine the renormalization of the system parameters and\nextract the arguments of the leading logarithmic terms (which can not be\nderived from usual renormalization group analysis). Furthermore, we perform the\nlow- and high-temperature limits. In the former, we find a behavior\ncharacteristic for the multichannel Kondo model."
    },
    {
        "anchor": "Three-Dimensional Fractional Topological Insulators in Coupled Rashba\n  Layers: We propose a model of three-dimensional topological insulators consisting of\nweakly coupled electron- and hole-gas layers with Rashba spin-orbit interaction\nstacked along a given axis. We show that in the presence of strong\nelectron-electron interactions the system realizes a fractional strong\ntopological insulator, where the rotational symmetry and condensation energy\narguments still allow us to treat the problem as quasi-one-dimensional with\nbosonization techniques. We also show that if Rashba and Dresselhaus spin-orbit\ninteraction terms are equally strong, by doping the system with magnetic\nimpurities, one can bring it into the Weyl semimetal phase.",
        "positive": "Quantum Interference Effects in Electronic Transport through Nanotube\n  Contacts: Quantum interference has dramatic effects on electronic transport through\nnanotube contacts. In optimal configuration the intertube conductance can\napproach that of a perfect nanotube ($4e^2/h$). The maximum conductance\nincreases rapidly with the contact length up to 10 nm, beyond which it exhibits\nlong wavelength oscillations. This is attributed to the resonant cavity-like\ninterference phenomena in the contact region. For two concentric nanotubes\nsymmetry breaking reduces the maximum intertube conductance from $4e^2/h$ to\n$2e^2/h$. The phenomena discussed here can serve as a foundation for building\nnanotube electronic circuits and high speed nanoscale electromechanical\ndevices."
    },
    {
        "anchor": "Direct measurement of the maximum tunnel rate in a radio frequency\n  single electron transistor operated as a microwave mixer: By operating the radio frequency single electron transistor (rf-SET) as a\nmixer we present measurements in which the RC roll-off of the tunnel junctions\nis observed at high frequencies. Our technique makes use of the non-linear\nrf-SET transconductance to mix high frequency gate signals and produce\ndifference-frequency components that fall within the bandwidth of the rf-SET.\nAt gate frequencies >15GHz the induced charge on the rf-SET island is altered\non time-scales faster than the inverse tunnel rate, preventing mixer operation.\nWe suggest the possibility of utilizing this technique to sense high frequency\nsignals beyond the usual rf-SET bandwidth.",
        "positive": "Temperature dependence of ambipolar diffusion in silicon-on-insulator: Spatiotemporal dynamics of electron-hole pairs locally excited in a\nsilicon-on-insulator structure by indirect interband absorption are studied by\nmeasuring differential transmission caused by free-carrier absorption of a\nprobe pulse tuned below the bandgap, with 200-fs temporal and 3-micrometer\nspatial resolution. From sample temperatures of 250 K to 400 K, the ambipolar\ndiffusivity decreases, and is similar to reported values of bulk silicon.\nCooling the sample from 250 K to 90 K, a decrease of ambipolar diffusivity is\nobserved, indicating important influences of defects and residual stress on\ncarrier diffusion. No detectable density dependence of ambipolar diffusivity is\nobserved."
    },
    {
        "anchor": "Spin-precession in an adiabatically rotating electric field: Due to spin-orbit coupling, the adiabatic perturbation of an electron's\norbital motion induced by a revolving external electric field lead to the\nelectron spin-precession. The obtained results describe both transverse and\nlongitudinal dynamics of an effective spin, for conical and figure-8\ntrajectories of a driving electric field, and elucidate the link between the\nquantum-mechanical, geometrical, and classical pictures of spin rotation.\nWithin the limit of adiabatic approximation the derived formulas are valid\nregardless of whether eigenvectors of the total Hamiltonian of the problem are\nexplicitly available or not, and are convenient for approximate calculations.\nThe main expression for the time evolution of the Bloch vector has pure\ngeometric character and is independent of the physical context.",
        "positive": "Engineering spin-orbit coupling for photons and polaritons in\n  microstructures: One of the most fundamental properties of electromagnetism and special\nrelativity is the coupling between the spin of an electron and its orbital\nmotion. This is at the origin of the fine structure in atoms, the spin Hall\neffect in semiconductors, and underlies many intriguing properties of\ntopological insulators, in particular their chiral edge states. Configurations\nwhere neutral particles experience an effective spin-orbit coupling have been\nrecently proposed and realized using ultracold atoms and photons. Here we use\ncoupled micropillars etched out of a semiconductor microcavity to engineer a\nspin-orbit Hamiltonian for photons and polaritons in a microstructure. The\ncoupling between the spin and orbital momentum arises from the polarisation\ndependent confinement and tunnelling of photons between micropillars arranged\nin the form of a hexagonal photonic molecule. Dramatic consequences of the\nspin-orbit coupling are experimentally observed in these structures in the\nwavefunction of polariton condensates, whose helical shape is directly visible\nin the spatially resolved polarisation patterns of the emitted light. The\nstrong optical nonlinearity of polariton systems suggests exciting perspectives\nfor using quantum fluids of polaritons11 for quantum simulation of the\ninterplay between interactions and spin-orbit coupling."
    },
    {
        "anchor": "Theory of charge density wave non-contact friction: A mechanism is proposed to describe the occurrence of distance-dependent\ndissipation peaks in the dynamics of an atomic force microscope tip oscillating\nover a surface characterized by a charge density wave state. The dissipation\nhas its origin in the hysteretic behavior of the tip oscillations occurring at\npositions compatible with a localized phase slip of the charge density wave.\nThis model is supported through static and dynamic numerical simulations of the\ntip surface interaction and is in good qualitative agreement with recently\nperformed experiments on a NbSe$_2$ sample.",
        "positive": "Kondo-resonance, Coulomb blockade, and Andreev transport through a\n  quantum dot: We study resonant tunneling through an interacting quantum dot coupled to\nnormal metallic and superconducting leads. We show that large Coulomb\ninteraction gives rise to novel effects in Andreev transport. Adopting an exact\nrelation for the Green's function, we find that at zero temperature, the linear\nresponse conductance is enhanced due to Kondo-Andreev resonance in the Kondo\nlimit, while it is suppressed in the empty site limit. In the Coulomb blockaded\nregion, on the other hand, the conductance is reduced more than the\ncorresponding conductance with normal leads because large charging energy\nsuppresses Andreev reflection."
    },
    {
        "anchor": "Boundary hopping and the mobility edge in the Anderson model in three\n  dimensions: It is shown, using high-precision numerical simulations, that the mobility\nedge of the 3d Anderson model depends on the boundary hopping term t in the\ninfinite size limit. The critical exponent is independent of it. The\nrenormalized localization length at the critical point is also found to depend\non t but not on the distribution of on-site energies for box and Lorentzian\ndistributions. Implications of results for the description of the transition in\nterms of a local order-parameter are discussed.",
        "positive": "Radiative cascades in charged quantum dots: We measured, for the first time, two photon radiative cascades due to\nsequential recombination of quantum dot confined electron hole pairs in the\npresence of an additional spectator charge carrier. We identified direct, all\noptical cascades involving spin blockaded intermediate states, and indirect\ncascades, in which non radiative relaxation precedes the second recombination.\nOur measurements provide also spin dephasing rates of confined carriers."
    },
    {
        "anchor": "Observation of dressed excitonic states in a single quantum dot: We report the observation of dressed states of a quantum dot. The optically\nexcited exciton and biexciton states of the quantum dot are coupled by a strong\nlaser field and the resulting spectral signatures are measured using\ndifferential transmission of a probe field. We demonstrate that the anisotropic\nelectron-hole exchange interaction induced splitting between the x- and\ny-polarized excitonic states can be completely erased by using the AC-Stark\neffect induced by the coupling field, without causing any appreciable\nbroadening of the spectral lines. We also show that by varying the polarization\nand strength of a resonant coupling field, we can effectively change the\npolarization-axis of the quantum dot.",
        "positive": "Full counting statistics of quantum phase slips: We work out a microscopic theory describing complete statistics of voltage\nfluctuations generated by quantum phase slips (QPS) in superconducting\nnanowires. We evaluate the cumulant generating function and demonstrate that\nshot noise of the voltage as well as the third and all higher voltage cumulants\ndiffer from zero only due to the presence of QPS. In the zero-frequency limit\nvoltage fluctuations in superconducting nanowires are described by Poisson\nstatistics just as in a number of other tunneling-like problems. However, at\nnon-zero frequencies quantum voltage fluctuations in superconducting nanowires\nbecome much more complicated and are not anymore accounted for by Poisson\nstatistics. In the case of short superconducting nanowires we explicitly\nevaluate all finite-frequency voltage cumulants and establish a non-trivial\nrelation between these cumulants and the current-voltage characteristics of our\nsystem."
    },
    {
        "anchor": "Quasi-bound States and Resonant Skew Scattering in Two-Dimensional\n  Materials with a Mexican-Hat Dispersion: Mexican-hat dispersion of band electrons in two-dimensional materials\nattracts a lot of interest, mainly due to the Van Hove singularity of the\ndensity of states near the band edge. In this paper, we show that there is one\nmore feature of such a dispersion, which also leads to nontrivial effects. It\nconsists in the fact that the sign of the effective mass in the momentum space\nnear the central extremum is opposite to the sign of the mass outside this\nregion. For this reason, any localized potential that repels quasiparticles in\nthe outer region attracts quasiparticles in the central region and thereby\ncreates quasi-bound states. We study these states in the case when the\nMexican-hat dispersion is formed due to the hybridization of the inverted\nelectron and hole bands, and the potential is created by a point defect. The\nenergy and width of the resonance of the local density of states corresponding\nto a quasi-bound state are found, and it is shown that, under certain\nconditions, a quasi-bound state can transform into a bound state in a continuum\nof band states. The presence of quasi-bound states leads to nontrivial effects\nin the spin-dependent scattering of electrons. Due to the quasi-bound state,\nthe skew scattering is strongly enhanced for electrons with energy near the\nresonance, and the skewness angle varies over a wide range depending on the\nenergy. In addition, in a certain energy range, a nontrivial effect of\nscattering suppression appears in the direction opposite to the skewness angle.",
        "positive": "Flat band, spin-1 Dirac cone, and Hofstadter diagram in the fermionic\n  square kagome model: We study characteristic band structures of the fermions on a square kagome\nlattice, one of the two-dimensional lattices hosting a corner-sharing network\nof triangles. We show that the band structures of the nearest-neighbor\ntight-binding model exhibit many characteristic features, including a flat band\nwhich is ubiquitous among frustrated lattices. On the flat band, we elucidate\nits origin by using the molecular-orbital representation and also find\nlocalized exact eigenstates called compact localized states. In addition to the\nflat band, we also find two spin-1 Dirac cones with different energies. These\nspin-1 Dirac cones are not described by the simplest effective Dirac\nHamiltonian because the middle band is bended and the energy spectrum is\nparticle-hole asymmetric. We also investigated the Hofstadter problem on a\nsquare kagome lattice in the presence of an external field and find that the\nprofile of the Chern numbers around the modified spin-1 Dirac cones coincides\nwith the conventional one."
    },
    {
        "anchor": "Impact of Many-Body Effects on Landau Levels in Graphene: We present magneto-Raman spectroscopy measurements on suspended graphene to\ninvestigate the charge carrier density-dependent electron-electron interaction\nin the presence of Landau levels. Utilizing gate-tunable magneto-phonon\nresonances, we extract the charge carrier density dependence of the Landau\nlevel transition energies and the associated effective Fermi velocity\n$v_\\mathrm{F}$. In contrast to the logarithmic divergence of $v_\\mathrm{F}$ at\nzero magnetic field, we find a piecewise linear scaling of $v_\\mathrm{F}$ as a\nfunction of charge carrier density, due to a magnetic field-induced suppression\nof the long-range Coulomb interaction. We quantitatively confirm our\nexperimental findings by performing tight-binding calculations on the level of\nthe Hartree-Fock approximation, which also allow us to estimate an excitonic\nbinding energy of $\\approx$ 6 meV contained in the experimentally extracted\nLandau level transitions energies.",
        "positive": "Localization and conductance fluctuations in the integer quantum Hall\n  effect: Real--space renormalization group approach: We consider the network model of the integer quantum Hall effect transition.\nBy generalizing the real--space renormalization group procedure for the\nclassical percolation to the case of quantum percolation, we derive a closed\nrenormalization group (RG) equation for the universal distribution of\nconductance of the quantum Hall sample at the transition. We find an\napproximate solution of the RG equation and use it to calculate the critical\nexponent of the localization length and the central moments of the conductance\ndistribution. The results obtained are compared with the results of recent\nnumerical simulations."
    },
    {
        "anchor": "1/(N-1) expansion for a finite U Anderson model away from half-filling: We apply recently developed 1/(N-1) expansion to a particle-hole asymmetric\nSU(N) Anderson model with finite Coulomb interaction U. To leading order in\n1/(N-1) it describes the Hartree-Fock random phase approximation (HF-RPA), and\nthe higher-order corrections describe systematically the fluctuations beyond\nthe HF-RPA. We show that the next-leading order results of the renormalized\nparameters for the local Fermi-liquid state agree closely with the numerical\nrenormalization group results at N=4. It ensures the reliability of the\nnext-leading order results for N>4, and we examine the N dependence of the\nlocal Fermi-liquid parameters. Our expansion scheme uses the standard Feynman\ndiagrams, and has wide potential applications.",
        "positive": "Vibrational modes and low-temperature thermal properties of graphene and\n  carbon nanotubes: A minimal force-constant model: We present a phenomenological force-constant model developed for the\ndescription of lattice dynamics of sp2 hybridized carbon networks. Within this\nmodel approach, we introduce a new set of parameters to calculate the phonon\ndispersion of graphene by fitting the ab initio dispersion. Vibrational modes\nof carbon nanotubes are obtained by folding the 2D dispersion of graphene and\napplying special corrections for the low-frequency modes. Particular attention\nis paid to the exact dispersion law of the acoustic modes, which determine the\nlow-frequency thermal properties and reveal quantum size effects in carbon\nnanotubes. On the basis of the resulting phonon spectra, we calculate the\nspecific heat and the thermal conductance for several achiral nanotubes of\ndifferent diameter. Through the temperature dependence of the specific heat we\ndemonstrate that phonon spectra of carbon nanotubes show one-dimensional\nbehavior and that the phonon subbands are quantized at low temperatures.\nConsequently, we prove the quantization of the phonon thermal conductance by\nmeans of an analysis based on the Landauer theory of heat transport."
    },
    {
        "anchor": "Tunable caging of excitation in decorated Lieb-ladder geometry with long\n  range connectivity: Controlled Aharonov-Bohm caging of wave train is reported in a quasi-one\ndimensional version of Lieb geometry with next nearest neighbor hopping\nintegral within the tight-binding framework. This longer wavelength fluctuation\nis considered by incorporating periodic, quasi-periodic or fractal kind of\ngeometry inside the skeleton of the original network. This invites exotic\neigenspectrum displaying a distribution of flat band states. Also a subtle\nmodulation of external magnetic flux leads to a comprehensive control over\nthose non-resonant modes. Real space renormalization group method provides us\nan exact analytical prescription for the study of such tunable imprisonment of\nexcitation. The non-trivial tunability of external agent is important as well\nas challenging in the context of experimental perspective.",
        "positive": "Designed Three-Dimensional Freestanding Single-Crystal Carbon\n  Architectures: Single-crystal carbon nanomaterials have led to great advances in\nnanotechnology. The first single-crystal carbon nanomaterial, fullerene, was\nfabricated in a zero-dimensional form. One-dimensional carbon nanotubes and\ntwo-dimensional graphene have since followed and continue to provide further\nimpetus to this field. In this study, we fabricated designed three-dimensional\n(3D) single-crystal carbon architectures by using silicon carbide templates.\nFor this method, a designed 3D SiC structure was transformed into a 3D\nfreestanding single-crystal carbon structure that retained the original SiC\nstructure by performing a simple single-step thermal process. The SiC structure\ninside the 3D carbon structure is self-etched, which results in a 3D\nfreestanding carbon structure. The 3D carbon structure is a single crystal with\nthe same hexagonal close-packed structure as graphene. The size of the carbon\nstructures can be controlled from the nanoscale to the microscale, and arrays\nof these structures can be scaled up to the wafer scale. The 3D freestanding\ncarbon structures were found to be mechanically stable even after repeated\nloading. The relationship between the reversible mechanical deformation of a\ncarbon structure and its electrical conductance was also investigated. Our\nmethod of fabricating designed 3D freestanding single-crystal graphene\narchitectures opens up prospects in the field of single-crystal carbon\nnanomaterials, and paves the way for the development of 3D single-crystal\ncarbon devices."
    },
    {
        "anchor": "How Does the Symmetry of S1 Influence Exciton Transport in Conjugated\n  Polymers?: Many optoelectronic devices based on organic materials require rapid and\nlong-range singlet exciton transport. Key factors that control the transport of\nsinglet excitons includes the electronic structure of the material, disorder\nand exciton-phonon coupling. An important parameter whose influence on exciton\ntransport has not been explored is the symmetry of the singlet electronic state\n(S1). Here, we employ femtosecond transient absorption spectroscopy and\nmicroscopy to reveal the relationship between the symmetry of S1 and exciton\ntransport in highly aligned, near-disorder free, one-dimensional conjugated\npolymers based on polydiacetylene.",
        "positive": "Non-Hermitian skin effect enforced by nonsymmorphic symmetries: Crystal symmetries play an essential role in band structures of non-Hermitian\nHamiltonian. In this paper, we propose a non-Hermitian skin effect (NHSE)\nenforced by nonsymmorphic symmetries. We show that the NHSE inevitably occurs\nif a two-dimensional non-Hermitian system satisfies conditions derived from the\nnonsymmorphic symmetry of the doubled Hermitian Hamiltonian. This NHSE occurs\nin symmetry classes with and without time-reversal symmetry. The NHSE enforced\nby nonsymmorphic symmetries always occurs simultaneously with the closing of\nthe point gap at zero energy. We also show that such a NHSE can occur in\nspecific three-dimensional space groups with nonsymmorphic symmetries."
    },
    {
        "anchor": "Glauber coherence of single electron sources: Recently demonstrated solid state single electron sources generate different\nquantum states depending on their operation condition. For adiabatic and\nnon-adiabatic sources we determine the Glauber correlation function in terms of\nthe Floquet scattering matrix of the source. The correlation function provides\nfull information on the shape of the state, on its time-dependent amplitude and\nphase, which makes the coherence properties of single electron states essential\nfor the production of quantum multi-particle states.",
        "positive": "Electric Control of Multiple Domain Walls in Pt/Co/Pt Nanotrack with\n  Perpendicular Magnetic Anisotropy: Electric control of multiple domain walls (DWs) motion is demonstrated by\nPt/Co/Pt nanotracks with perpendicular magnetic anisotropy. Due to the weak\nmicrostructural disorders with small DW propagation field, the purely\ncurrent-driven DW motion is achieved in the creep regime at current densities\nless than 10^7 A/cm^2 at room temperature. It is confirmed that by use of a\nscanning magneto-optical Kerr effect microscope, several DWs are simultaneously\nand identically displaced by the same distance in the same direction. Utilizing\nsuch DWs motion, we succeed to realize random bits writing and transferring as\na device prototype of four-bit shift registers."
    },
    {
        "anchor": "Ultrafast charge ordering by self-amplified exciton-phonon dynamics in\n  TiSe$_2$: The origin of charge density waves (CDW) in TiSe$_2$ has long been debated,\nmainly due to the difficulties in identifying the timescales of how and when\nthe excitonic pairing and electron-phonon coupling (EPC) come into play.\nWithout a proper time resolution and microscopic mechanism, one has to assume\nsimultaneous appearance of CDW and periodic lattice distortions (PLD). Here, we\naccomplish a complete separation of exciton and PLD dynamics and unravel their\ninterplay in the ultrafast time domain in our real-time time-dependent density\nfunctional theory simulations. We find that laser pulses knock off the exciton\norder and induce a homogeneous bonding-antibonding transition in the initial 20\nfs, then the weakened electronic order triggers ionic movements antiparallel to\nthe original PLD. The EPC comes into play after the initial 20~fs, and the two\nprocesses mutually amplify each other leading to a complete inversion of CDW\nordering. The self-amplified dynamics reproduces the evolution of band\nstructures in excellent agreement with ultrafast photoemission experiment.\nHence we resolve the key processes in the initial dynamics of CDW that help\nelucidate the mechanism underlying the long debated problem.",
        "positive": "Observation of a Dirac point in microwave experiments with a photonic\n  crystal modeling graphene: We present measurements of transmission and reflection spectra of a microwave\nphotonic crystal composed of 874 metallic cylinders arranged in a triangular\nlattice. The spectra show clear evidence of a Dirac point, a characteristic of\na spectrum of relativistic massless fermions. In fact, Dirac points are a\npeculiar property of the electronic band structure of graphene, whose\nproperties consequently can be described by the relativistic Dirac equation. In\nthe vicinity of the Dirac point, the measured reflection spectra resemble those\nobtained by conductance measurements in scanning tunneling microscopy of\ngraphene flakes."
    },
    {
        "anchor": "Metasurface-mediated anisotropic radiative heat transfer between\n  nanoparticles: Metasurfaces, the two-dimensional (2D) counterpart of metamaterials, have\nrecently attracted a great attention due to their amazing properties such as\nnegative refraction, hyperbolic dispersion, manipulation of the evanescent\nspectrum. In this work, we propose a theory model for the near field radiative\nheat transfer (NFRHT) between two nanoparticles in the presence of an\nanisotropic metasurface. Specifically, we set the metasurface as an array of\ngraphene strips (GS) since it is an ideal platform to implement any metasurface\ntopology, ranging from isotropic to hyperbolic propagation. We show that the\nNFRHT between two nanoparticles can not only be significantly amplified when\nthey are placed in proximity of the GS, but also be regulated over several\norders of magnitude. In this configuration, the anisotropic surface plasmon\npolaritons (SPPs) supported by the GS are excited and provide a new channel for\nthe near-field energy transport. We analyze how the conductance between two\nnanoparticles depends on the orientation, the structure parameters and the\nchemical potential of the GS, on the particle-surface or the particle-surface\ndistances by clearly identifying the characteristics of the anisotropic SPPs\nsuch as dispersion relations, propagation length and decay length. Our findings\nprovide a powerful way to regulate the energy transport in the particle\nsystems, meanwhile in turn, open up a way to explore the anisotropic optical\nproperties of the metasurface based on the measured heat transfer properties.",
        "positive": "Power dissipation in spintronic devices: A general perspective: Champions of spintronics often claim that spin based signal processing\ndevices will vastly increase speed and/or reduce power dissipation compared to\ntraditional charge based electronic devices. Yet, not a single spintronic\ndevice exists today that can lend credence to this claim. Here, I show that no\nspintronic device that clones conventional electronic devices, such as field\neffect transistors and bipolar junction transistors, is likely to reduce power\ndissipation significantly. For that to happen, spin-based devices must forsake\nthe transistor paradigm of switching states by physical movement of charges,\nand instead, switch states by flipping spins of stationary charges. An\nembodiment of this approach is the single spin logic idea proposed more than 10\nyears ago. Here, I revisit that idea and present estimates of the switching\nspeed and power dissipation. I show that the Single Spin Switch is far superior\nto the Spin Field Effect Transistor (or any of its clones) in terms of power\ndissipation. I also introduce the notion of matrix element engineering which\nwill allow one to switch devices without raising and lowering energy barriers\nbetween logic states, thereby circumventing the kTln2 limit on energy\ndissipation. Finally, I briefly discuss single spin implementations of\nclassical reversible (adiabatic) logic."
    },
    {
        "anchor": "Torsion, Parity-odd Response and Anomalies in Topological States: We study the response of a class of topological systems to electromagnetic\nand gravitational sources, including torsion and curvature. By using the\ntechnology of anomaly polynomials, we derive the parity-odd response of a\nmassive Dirac fermion in $d=2+1$ and $d=4+1$, which provides a simple model for\na topological insulator. We discuss the covariant anomalies of the\ncorresponding edge states, from a Callan-Harvey anomaly-inflow, as well as a\nHamiltonian spectral flow point of view. We also discuss the applicability of\nour results to other systems such as Weyl semi-metals. Finally, using\ndimensional reduction from $d=4+1$, we derive the effective action for a\n$d=3+1$ time-reversal invariant topological insulator in the presence of\ntorsion and curvature, and discuss its various physical consequences.",
        "positive": "Chiral properties of topological-state loops: The angular momentum quantization of chiral gapless modes confined to a\ncircularly shaped interface between two different topological phases is\ninvestigated. By examining several different setups, we show analytically that\nthe angular momentum of the topological modes exhibits a highly chiral\nbehavior, and can be coupled to spin and/or valley degrees of freedom,\nreflecting the nature of the interface states. The energies and the magnetic\nmoments corresponding to these states can be understood from a semiclassical\npicture. These loops can be viewed as building blocks for artificial magnets\nwith tunable and highly diverse properties."
    },
    {
        "anchor": "Coherent transport in linear arrays of quantum dots: the effects of\n  period doubling and of quasi-periodicity: We evaluate the phase-coherent transport of electrons along linear structures\nof varying length, which are made from two types of potential wells set in\neither a periodic or a Fibonacci quasi-periodic sequence. The array is\ndescribed by a tight-binding Hamiltonian and is reduced to an effective dimer\nby means of a decimation-renormalization method, extended to allow for\nconnection to external metallic leads, and the transmission coefficient is\nevaluated in a T-matrix scattering approach. Parallel behaviors are found for\nthe energy dependence of the density of electron states and of the\ntransmittivity of the array. In particular, we explicitly show that on\nincreasing its length the periodic array undergoes a metal-insulator transition\nnear single occupancy per dot, whereas prominent pseudo-gaps emerge away from\nthe band center in the Fibonacci-ordered array.",
        "positive": "Bilayer graphene as an helical quantum Hall ferromagnet: The two-dimensional electron gas in a bilayer graphene in the Bernal stacking\nsupports a variety of uniform broken-symmetry ground states in Landau level N=0\nat integer filling factors $\\nu \\in [-3,4].$ When an electric potential\ndifference (or bias) is applied between the layers at filling factors $\\nu\n=-1,3$, the ground state evolves from an interlayer coherent state at small\nbias to a state with orbital coherence at higher bias where \\textit{electric}\ndipoles associated with the orbital pseudospins order spontaneously in the\nplane of the layers. In this paper, we show that by further increasing the bias\nat these two filling factors, the two-dimensional electron gas goes first\nthrough a Skyrmion crystal state and then into an helical state where the\npseudospins rotate in space. The pseudospin textures in both the Skyrmion and\nhelical states are due to the presence of a Dzyaloshinskii-Moriya interaction\nin the effective pseudospin Hamiltonian when orbital coherence is present in\nthe ground state. We study in detail the electronic structure of the helical\nand Skyrmion crystal states as well as their collective excitations and then\ncompute their electromagnetic absorption."
    },
    {
        "anchor": "Magnetic breakdown and Klein tunneling in a type-II Weyl semimetal: The band structure of a type-II Weyl semimetal has pairs of electron and hole\npockets that coexist over a range of energies and touch at a topologically\nprotected conical point. We identify signatures of this Weyl point in the\nmagnetic quantum oscillations of the density of states, observable in\nthermodynamic properties. Tunneling between the electron and hole pockets in a\nmagnetic field is the momentum space counterpart of Klein tunneling at a p-n\njunction in real space. This magnetic breakdown happens at a characteristic\nfield that vanishes when the Fermi level approaches the Weyl point.\nTopologically distinct, connected or disconnected, pairs of type-II Weyl cones\ncan be distinguished by the qualitatively different dependence of the quantum\noscillations on the direction of the magnetic field.",
        "positive": "Decay and fusion as two different mechanisms of stability loss for the\n  (C_20)_2 cluster dimer: The thermal stability of the (C_20)_2 cluster dimer consisting of two C_20\nfullerenes is examined using a tight-binding approach. Molecular dynamics\nsimulations of the (C_20)_2 dimer at temperatures T = 2000 - 3500 K show that\nthe finite lifetime \\tau of this metastable system is determined by two\nfundamentally different processes, the decay of one of the C_20 fullerenes and\nthe fusion of two C_20 fullerenes into the C_40 cluster. The activation\nenergies for these processes Ea = 3.4 and 2.7 eV, respectively, as well as\ntheir frequency factors, have been determined by analyzing the dependence of\n\\tau on T."
    },
    {
        "anchor": "Ab-initio methods for spin-transport at the nanoscale level: Recent advances in atomic and nano-scale growth and characterization\ntechniques have led to the production of modern magnetic materials and\nmagneto-devices which reveal a range of new fascinating phenomena. The modeling\nof these is a tough theoretical challenging since one has to describe\naccurately both electronic structure of the constituent materials, and their\ntransport properties. In this paper I review recent advances in modeling\nspin-transport at the atomic scale using first-principles methods, focusing\nboth on the methodological aspects and on the applications. The review, which\nis designed as tutorial for students at postgraduate level, is structured in\nsix main sections: 1) Introduction, 2) General concepts in spin-transport, 3)\nTransport Theory: Linear Response, 4) Transport Theory: Non-equilibrium\nTransport, 5) Results, 6) Conclusion. In addition an overview of the\ncomputational codes available to date is also included.",
        "positive": "Electron interactions, classical integrability, and level statistics in\n  quantum dots: The role of electronic interactions in the level structure of semiconductor\nquantum dots is analyzed in terms of the correspondence to the integrability of\na classical system that models these structures. We find that an otherwise\nsimple system is made strongly non-integrable in the classical regime by the\nintroduction of particle interactions. In particular we present a two-particle\nclassical system contained in a $d$-dimensional billiard with hard walls.\nSimilarly, a corresponding two-dimensional quantum dot problem with three\nparticles is shown to have interesting spectral properties as function of the\ninteraction strength and applied magnetic fields."
    },
    {
        "anchor": "Magneto-optical properties of multilayer graphenes: The magneto-optical absorption properties of graphene multilayers are\ntheoretically studied. It is shown that the spectrum can be decomposed into\nsub-components effectively identical to the monolayer or bilayer graphene,\nallowing us to understand the spectrum systematically as a function of the\nlayer number. Odd-layered graphenes always exhibit absorption peaks which\nshifts in proportion to sqrt(B), with B being the magnetic field, due to the\nexistence of an effective monolayer-like subband. We propose a possibility of\nobserving the monolayer-like spectrum even in a mixture of multilayer graphene\nfilms with various layers numbers.",
        "positive": "Atomistic simulations of the sliding friction of graphene flakes: Using a tight-binding atomistic simulation, we simulate the recent\natomic-force microscopy experiments probing the slipperiness of graphene flakes\nmade slide against a graphite surface. Compared to previous theoretical models,\nwhere the flake was assumed to be geometrically perfect and rigid, while the\nsubstrate is represented by a static periodic potential, our fully-atomistic\nmodel includes quantum mechanics with the chemistry of bond breaking and bond\nformation, and the flexibility of the flake. These realistic features, include\nin particular the crucial role of the flake rotation in determining the static\nfriction, in qualitative agreement with experimental observations."
    },
    {
        "anchor": "Boundary edge networks induced by bulk topology: We introduce an effective edge network theory to characterize the boundary\ntopology of coupled edge states generated from various types of topological\ninsulators. Two examples studied are a two-dimensional second-order topological\ninsulator and three-dimensional topological fullerenes, which involve multi-leg\njunctions. As a consequence of bulk-edge correspondence, these edge networks\ncan faithfully predict properties such as the energy and fractional charge\nrelated to the bound states (edge solitons) in the aforementioned systems,\nincluding several aspects that were previously complicated or obscure.",
        "positive": "Quantum Hall Drag of Exciton Superfluid in Graphene: Excitons are pairs of electrons and holes bound together by the Coulomb\ninteraction. At low temperatures, excitons can form a Bose-Einstein condensate\n(BEC), enabling macroscopic phase coherence and superfluidity. An electronic\ndouble layer (EDL), in which two parallel conducting layers are separated by an\ninsulator, is an ideal platform to realize a stable exciton BEC. In an EDL\nunder strong magnetic fields, electron-like and hole-like quasi-particles from\npartially filled Landau levels (LLs) bind into excitons and condense. However,\nin semiconducting double quantum wells, this magnetic-field-induced exciton BEC\nhas been observed only in sub-Kelvin temperatures due to the relatively strong\ndielectric screening and large separation of the EDL. Here we report exciton\ncondensation in bilayer graphene EDL separated by a few atomic layers of\nhexagonal boron nitride (hBN). Driving current in one graphene layer generates\na quantized Hall voltage in the other layer, signifying coherent superfluid\nexciton transport. Owing to the strong Coulomb coupling across the atomically\nthin dielectric, we find that quantum Hall drag in graphene appears at a\ntemperature an order of magnitude higher than previously observed in GaAs EDL.\nThe wide-range tunability of densities and displacement fields enables\nexploration of a rich phase diagram of BEC across Landau levels with different\nfilling factors and internal quantum degrees of freedom. The observed robust\nexciton superfluidity opens up opportunities to investigate various quantum\nphases of the exciton BEC and design novel electronic devices based on\ndissipationless transport."
    },
    {
        "anchor": "Frequency fluctuations of ferromagnetic resonances at milliKelvin\n  temperatures: Unwanted fluctuations over time, in short, noise, are detrimental to device\nperformance, especially for quantum coherent circuits. Recent efforts have\ndemonstrated routes to utilizing magnon systems for quantum technologies, which\nare based on interfacing single magnons to superconducting qubits. However, the\ncoupling of several components often introduces additional noise to the system,\ndegrading its coherence. Researching the temporal behavior can help to identify\nthe underlying noise sources, which is a vital step in increasing coherence\ntimes and the hybrid device performance. Yet, the frequency noise of the\nferromagnetic resonance (FMR) has so far been unexplored. Here, we investigate\nsuch FMR frequency fluctuations of a YIG sphere down to mK-temperatures, and\nfind them independent of temperature and drive power. This suggests that the\nmeasured frequency noise in YIG is dominated by so far undetermined noise\nsources, which properties are not consistent with the conventional model of\ntwo-level systems, despite their effect on the sample linewidth. Moreover, the\nfunctional form of the FMR frequency noise power spectral density (PSD) cannot\nbe described by a simple power law. By employing time-series analysis, we find\na closed function for the PSD that fits our observations. Our results underline\nthe necessity of coherence improvements to magnon systems for useful\napplications in quantum magnonics.",
        "positive": "Coherent Charge Oscillations in a Bilayer Graphene Double Quantum Dot: The coherent dynamics of a quantum mechanical two-level system passing\nthrough an anti-crossing of two energy levels can give rise to\nLandau-Zener-St\\\"uckelberg-Majorana (LZSM) interference. LZSM interference\nspectroscopy has proven to be a fruitful tool to investigate charge noise and\ncharge decoherence in semiconductor quantum dots (QDs). Recently, bilayer\ngraphene has developed as a promising platform to host highly tunable QDs\npotentially useful for hosting spin and valley qubits. So far, in this system\nno coherent oscillations have been observed and little is known about charge\nnoise in this material. Here, we report coherent charge oscillations and\n$T_2^*$ charge decoherence times in a bilayer graphene double QD. The charge\ndecoherence times are measured independently using LZSM interference and photon\nassisted tunneling. Both techniques yield $T_2^*$ average values in the range\nof 400 to 500 ps. The observation of charge coherence allows to study the\norigin and spectral distribution of charge noise in future experiments."
    },
    {
        "anchor": "Protected Fermionic Zero Modes in Periodic Gauge Fields: It is well-known that macroscopically-normalizable zero-energy wavefunctions\nof spin-$\\frac{1}{2}$ particles in a two-dimensional inhomogeneous magnetic\nfield are spin-polarized and exactly calculable with degeneracy equaling the\nnumber of flux quanta linking the whole system. Extending this argument to\nmassless Dirac fermions subjected to magnetic fields that have \\textit{zero}\nnet flux but are doubly periodic in real space, we show that there exist\n\\textit{only two} Bloch-normalizable zero-energy eigenstates, one for each spin\nflavor. This result is immediately relevant to graphene multilayer systems\nsubjected to doubly-periodic strain fields, which at low energies, enter the\nHamiltonian as periodic pseudo-gauge vector potentials. Furthermore, we explore\nvarious related settings including nonlinearly-dispersing band structure models\nand systems with singly-periodic magnetic fields.",
        "positive": "Evidence for a finite temperature phase transition in a bilayer quantum\n  Hall system: We study the Josephson-like interlayer tunneling signature of the strongly\ncorrelated $\\nu_T = 1$ quantum Hall phase in bilayer two-dimensional electron\nsystems as a function of the layer separation, temperature and interlayer\ncharge imbalance. Our results offer strong evidence that a finite temperature\nphase transition separates the interlayer coherent phase from incoherent phases\nwhich lack strong interlayer correlations. The transition temperature is\ndependent on both the layer spacing and charge imbalance between the layers."
    },
    {
        "anchor": "Lack of near-sightedness principle in non-Hermitian systems: The non-Hermitian skin effect is a phenomenon in which an extensive number of\nstates accumulates at the boundaries of a system. It has been associated to\nnontrivial topology, with nonzero bulk invariants predicting its appearance and\nits position in real space. Here we demonstrate that the non-Hermitian skin\neffect is not a topological phenomenon in general: when translation symmetry is\nbroken by a single non-Hermitian impurity, skin modes are depleted at the\nboundary and accumulate at the impurity site, without changing any bulk\ninvariant. This may occur even for a fully Hermitian bulk.",
        "positive": "Shell filling in closed single-wall carbon nanotube quantum dots: We observe two-fold shell filling in the spectra of closed one-dimensional\nquantum dots formed in single-wall carbon nanotubes. Its signatures include a\nbimodal distribution of addition energies, correlations in the excitation\nspectra for different electron number, and alternation of the spins of the\nadded electrons. This provides a contrast with quantum dots in higher\ndimensions, where such spin pairing is absent. We also see indications of an\nadditional fourfold periodicity indicative of K-K' subband shells. Our results\nsuggest that the absence of shell filling in most isolated nanotube dots\nresults from disorder or nonuniformity."
    },
    {
        "anchor": "Group-velocity slowdown in a double quantum-dot molecule: The slowdown of optical pulses due to quantum-coherence effects is\ninvestigated theoretically for an \"active material\" consisting of InGaAs-based\ndouble quantum-dot molecules. These are designed to exhibit a long lived\ncoherence between two electronic levels, which is an essential part of a\nquantum coherence scheme that makes use of electromagnetically-induced\ntransparency effects to achieve group velocity slowdown. We apply a\nmany-particle approach based on realistic semiconductor parameters that allows\nus to calculate the quantum-dot material dynamics including microscopic carrier\nscattering and polarisation dephasing dynamics. The group-velocity reduction is\ncharacterized in the frequency domain by a quasi-equilibrium slow-down factor\nand in the time domain by the probe-pulse slowdown obtained from a calculation\nof the spatio-temporal material dynamics coupled to the propagating optical\nfield. The group-velocity slowdown in the quantum-dot molecule is shown to be\nsubstantially higher than what is achievable from similar transitions in\ntypical InGaAs-based single quantum dots. The dependences of slowdown and shape\nof the propagating probe pulses on lattice temperature and drive intensities\nare investigated.",
        "positive": "Radiation Pressure Quantization: Kepler's observation of comets tails initiated the research on the radiation\npressure of celestial objects and 250 years later they found new incarnation\nafter the Maxwell's equations were formulated to describe a plethora of\nlight-matter coupling phenomena. Further, quantum mechanics gave birth to the\nphoton drag effect. Here, we predict a novel universal phenomenon which can be\nreferred to as quantization of the radiation pressure. We develop a microscopic\ntheory of this effect which can be applied to a general system containing\nBose-Einstein-condensed particles, which possess an internal structure of\nquantum states. By analyzing the response of the system to an external\nelectromagnetic field we find that such drag results in a flux of particles\nconstituting both the condensate and the excited states. We show that in the\npresence of the condensed phase, the response of the system becomes quantized\nwhich manifests itself in a step-like behavior of the particle flux as a\nfunction of electromagnetic field frequency with the elementary quantum\ndetermined by the internal energy structure of the particles."
    },
    {
        "anchor": "Electron Transfer between Weakly Coupled Concentric Quantum Rings: The electronic structure of the semiconductor double concentric quantum\nnano-ring (DCQR) is studied under the single sub-band effective mass approach.\nWe show that in the weakly coupled DCQR, that has been placed in transverse\nmagnetic field, the electron spatial transition between the rings can occur due\nto electron level anti-crossing. The anti-crossing of the levels with different\nradial quantum numbers provides the conditions when the electron tunneling\nbetween rings becomes possible. Results of numerical simulation for the\nelectron transition are presented for DCQRs of different geometry. In\nparticularly, the system of a QR with a QD located at center of this QR is\nconsidered.",
        "positive": "Theory for entanglement of electrons dressed with circularly polarized\n  light in Graphene and three-dimensional topological insulators: We have formulated a theory for investigating the conditions which are\nrequired to achieve entangled states of electrons on graphene and\nthree-dimensional (3D) topological insulators (TIs). We consider the quantum\nentanglement of spins by calculating the exchange energy. A gap is opened up at\nthe Fermi level between the valence and conduction bands in the absence of\ndoping when graphene as well as 3D TIs are irradiated with circularly-polarized\nlight. This energy band gap is dependent on the intensity and frequency of the\napplied electromagnetic field. The electron-photon coupling also gives rise to\na unique energy dispersion of the dressed states which is different from either\ngraphene or the conventional two-dimensional electron gas (2DEG). In our\ncalculations, we obtained the dynamical polarization function for imaginary\nfrequencies which is then employed to determine the exchange energy. The\npolarization function is obtained with the use of both the energy eigenstates\nand the overlap of pseudo-spin wave functions. We have concluded that while\ndoping has a significant influence on the exchange energy and consequently on\nthe entanglement, the gap of the energy dispersions affects the exchange\nslightly, which could be used as a good technique to tune and control\nentanglement for quantum information purposes."
    },
    {
        "anchor": "Four-wave mixing in Weyl semimetals: Weyl semimetals (WSMs) have unusual optical response originated from unique\ntopological properties of their bulk and surface electron states. Their\nthird-order optical nonlinearity is expected to be very strong, especially at\nlong wavelengths, due to linear dispersion and high Fermi velocity of\nthree-dimensional Weyl fermions. Here we derive the third-order nonlinear\noptical conductivity of WSMs in the long-wavelength limit and calculate the\nintensity of the nonlinear four-wave mixing signal as it is transmitted through\nthe WSM film or propagates away from the surface of the material in the\nreflection geometry. All results are analytic and show the scaling of the\nsignal intensity with variation of all relevant parameters. The nonlinear\ngeneration efficiency turns out to be surprisingly high for a lossy material,\nof the order of several mW per W$^3$ of the incident pump power. Optimal\nconditions for maximizing the nonlinear signal are realized in the vicinity of\nbulk plasma resonance. This indicates that ultrathin WSM films of the order of\nskin depth in thickness could find applications in compact optoelectronic\ndevices.",
        "positive": "Ultrahigh Frequency and Multi-channel Output in Skyrmion Based\n  Nano-oscillator: Spintronic nano-oscillators can generate tunable microwave signals that find\na wide range of applications in the field of telecommunication to modern\nneuromorphic computing systems. Among other spintronic devices, a magnetic\nskyrmion is a promising candidate for the next generation of low-power devices\ndue to its small size and topological stability. In this work, we propose a\nmulti-channel oscillator design based on the synthetic anti-ferromagnetic (SAF)\nskyrmion pair. The mitigation of the skyrmion Hall effect in SAF and the\nassociated decimation of the Magnus force endows the proposed oscillator with\nan ultra-high frequency of 41GHz and a multi-channel frequency output driven by\nthe same current. The ultrahigh operational frequency represents an $\\sim$342\ntimes improvement compared to the monolayer single skyrmion oscillator\nfeaturing a constant uniaxial anisotropy profile. Using micromagnetic\nsimulations, we demonstrate the effectiveness of our proposed multi-channel\noscillator design by introducing multi-channel nanotracks along with multiple\nskyrmions for enhanced frequency operation. The ultrahigh operational frequency\nand multi-channel output are attributed to three key factors: The oscillator\ndesign accounting for a finite spin-flip length of the spacer (such as Ru)\nmaterial, tangential velocity proportionality on input spin current along with\nweak dependence on the radius of rotation of the skyrmion-pair, skyrmion\ninterlocking in the channel enabled by the multi-channel high Ku rings and\nskyrmion-skyrmion repulsion, therefore resulting ultrahigh frequency and\nmulti-channel outputs."
    },
    {
        "anchor": "Non-conventional graphene superlattices as electron band-pass filters: Electron transmission through different gated and gapped graphene\nsuperlattices (GSLs) is studied. Linear, Gaussian, Lorentzian and\nP\\\"oschl-Teller superlattice potential profiles have been assessed. A\nrelativistic description of electrons in graphene as well as the transfer\nmatrix method have been used to obtain the transmission properties. We find\nthat is not possible to have perfect or nearly perfect pass bands in gated\nGSLs. Regardless of the potential profile and the number of barriers there are\nremanent oscillations in the transmission bands. On the contrary, nearly\nperfect pass bands are obtained for gapped GSLs. The Gaussian profile is the\nbest option when the number of barriers is reduced, and there is practically no\ndifference among the profiles for large number of barriers. We also find that\nboth gated and gapped GSLs can work as omnidirectional band-pass filters. In\nthe case of gated Gaussian GSLs the omnidirectional range goes from\n-$50^{\\circ}$ to $50^{\\circ}$ with an energy bandwidth of 55 meV, while for\ngapped Gaussian GSLs the range goes from -$80^{\\circ}$ to $80^{\\circ}$ with a\nbandwidth of 40 meV. Here, it is important that the energy range does not\ninclude remanent oscillations. On the light of these results, the hole states\ninside the barriers of gated GSLs are not beneficial for band-pass filtering.\nSo, the flatness of the pass bands is determined by the superlattice potential\nprofile and the chiral nature of the charge carriers in graphene. Moreover, the\nwidth and the number of electron pass bands can be modulated through the\nsuperlattice structural parameters. We consider that our findings can be useful\nto design electron filters based on non-conventional GSLs.",
        "positive": "Anomalous suppression of the shot noise in a nanoelectromechanical\n  system: In this paper we report a relaxation-induced suppression of the noise for a\nsingle level quantum dot coupled to an oscillator with incoherent dynamics in\nthe sequential tunneling regime. It is shown that relaxation induces\nqualitative changes in the transport properties of the dot, depending on the\nstrength of the electron-phonon coupling and on the applied voltage. In\nparticular, critical thresholds in voltage and relaxation are found such that a\nsuppression below 1/2 of the Fano factor is possible. Additionally, the current\nis either enhanced or suppressed by increasing relaxation, depending on bias\nbeing greater or smaller than the above threshold. These results exist for any\nstrength of the electron-phonon coupling and are confirmed by a four states toy\nmodel."
    },
    {
        "anchor": "Spin-orbit coupling measurement by the scanning gate microscopy: We propose a procedure for extraction of the Fermi surface for a\ntwo-dimensional electron gas with a strong Rashba spin-orbit coupling from\nconductance microscopy. Due to the interplay between the effective spin-orbit\nmagnetic field and the external one within the plane of confinement, the\nbackscattering induced by a charged tip of an atomic force microscope located\nabove the sample, leads to the spin precession, and thus to the spin mixing of\nthe incident and reflected modes. This mixing leads to a characteristic\nangle-dependent beating pattern visible in the conductance maps. We show that\nthe structure of the Fermi level, bearing signatures of the spin-orbit\ncoupling, can be extracted from the Fourier transform of the interference\nfringes in the conductance maps as a function of the magnetic field direction.\nWe propose a simple analytical model which can be used to fit the experimental\ndata in order to obtain the spin-orbit coupling constant.",
        "positive": "Permanent current from non-commutative spin algebra: We show that a spontaneous electric current is induced in a nano-scale\nconducting ring just by putting three ferromagnets. The current is a direct\nconsequence of the non-commutativity of the spin algebra, and is proportional\nto the non-coplanarity (chirality) of the magnetization vectors. The\nspontaneous current gives a natural explanation to the chirality-driven\nanomalous Hall effect."
    },
    {
        "anchor": "Polarization as a topological quantum number in graphene: Graphene, with its quantum Hall topological (Chern) number reflecting the\nmassless Dirac particle, is shown to harbor yet another topological quantum\nnumber. This is obtained by combining Streda's general formula for the\npolarization associated with a second topological number in the Diophantine\nequation for the Hofstadter problem, and the adiabatic continuity, earlier\nshown to exist between the square and honeycomb lattices by Hatsugai et al.\nSpecifically, we can regard, from the adiabatic continuity, graphene as a\n``simulator\" of square lattice with half flux quantum per unit cell, which\nimplies that the polarization topological numbers in graphene in weak magnetic\nfields is 1/2 per Dirac cone for the energy region between the van Hove\nsingularities, signifying a new quantum number characterizing graphene.",
        "positive": "Electron motion in a Holstein molecular chain in an electric field: A charge motion in an electric field in a Holstein molecular chain is modeled\nin the absence of dissipation. It is shown that in a weak electric field a\nHolstein polaron moves uniformly experiencing small oscillations of its shape.\nThese oscillations are associated with the chain's discreteness and caused by\nthe presence of Peierls-Nabarro potential there. The critical value of the\nelectric field intensity at which the moving polaron starts oscillating at\nBloch frequency is found. It is shown that the polaron can demonstrate Bloch\noscillations retaining its shape. It is also shown that a breathing mode of\nBloch oscillations can arise. In all cases the polaron motion along the chain\nis infinite."
    },
    {
        "anchor": "Semi-analytical model of the contact resistance in two-dimensional\n  semiconductors: Contact resistance is a severe performance bottleneck for electronic devices\nbased on two-dimensional layered (2D) semiconductors, whose contacts are\nSchottky rather than Ohmic. Although there is general consensus that the\ninjection mechanism changes from thermionic to tunneling with gate biasing,\nexisting models tend to oversimplify the transport problem, by neglecting the\n2D transport nature and the modulation of the Schottky barrier height, the\nlatter being of particular importance in back-gated devices. In this work, we\ndevelop a semi-analytical model based on Bardeen's transfer Hamiltonian\napproach to describe both effects. Remarkably, our model is able to reproduce\nseveral experimental observations of a metallic behavior in the contact\nresistance, i.e., a decreasing resistance with decreasing temperature,\noccurring at high gate voltage.",
        "positive": "Graphene Transistor as a Probe for Streaming Potential: We explore the dependence of electrical transport in a graphene field effect\ntransistor (GraFET) on the flow of the liquid within the immediate vicinity of\nthat transistor. We find large and reproducible shifts in the charge neutrality\npoint of GraFETs that are dependent on the fluid velocity and the ionic\nconcentration. We show that these shifts are consistent with the variation of\nthe local electrochemical potential of the liquid next to graphene that are\ncaused by the fluid flow (streaming potential). Furthermore, we utilize the\nsensitivity of electrical transport in GraFETs to the parameters of the fluid\nflow to demonstrate graphene-based mass flow and ionic concentration sensing.\nWe successfully detect a flow as small as~70nL/min, and detect a change in the\nionic concentration as small as ~40nM."
    },
    {
        "anchor": "Quantum Oscillations of Gilbert Damping in Ferromagnetic/Graphene\n  Bilayer Systems: We study the spin dynamics of a ferromagnetic insulator on which graphene is\nplaced. We show that the Gilbert damping is enhanced by the proximity exchange\ncoupling at the interface. The modulation of the Gilbert damping constant is\nproportional to the product of the spin-up and spin-down densities of states of\ngraphene. Consequently, the Gilbert damping constant in a strong magnetic field\noscillates as a function of the external magnetic field that originates from\nthe Landau level structure of graphene. We find that a measurement of the\noscillation period enables the strength of the exchange coupling constant to be\ndetermined. The results demonstrate in theory that the ferromagnetic resonance\nmeasurements may be used to detect the spin resolved electronic structure of\nthe adjacent materials, which is critically important for future spin device\nevaluations.",
        "positive": "Decoherence and Full Counting Statistics in a Mach-Zehnder\n  Interferometer: We investigate the Full Counting Statistics of an electrical Mach-Zehnder\ninterferometer penetrated by an Aharonov-Bohm flux, and in the presence of a\nclassical fluctuating potential. Of interest is the suppression of the\nAharonov-Bohm oscillations in the distribution function of the transmitted\ncharge. For a Gaussian fluctuating field we calculate the first three\ncumulants. The fluctuating potential causes a modulation of the conductance\nleading in the third cumulant to a term cubic in voltage and to a contribution\ncorrelating modulation of current and noise. In the high voltage regime we\npresent an approximation of the generating function."
    },
    {
        "anchor": "Liquid Crystal Phases of Quantum Hall Systems: Mean-field calculations for the two dimensional electron gas (2DEG) in a\nlarge magnetic field with a partially filled Landau level with index $N\\geq 2$\nconsistently yield ``stripe-ordered'' charge-density wave ground-states, for\nmuch the same reason that frustrated phase separation leads to stripe ordered\nstates in doped Mott insulators. We have studied the effects of quantum and\nthermal fluctuations about such a state and show that they can lead to a set of\nelectronic liquid crystalline states, particularly a stripe-nematic phase which\nis stable at $T>0$. Recent measurements of the longitudinal resistivity of a\nset of quantum Hall devices have revealed that these systems spontaneously\ndevelop, at low temepratures, a very large anisotropy. We interpret these\nexperiments as evidence for a stripe nematic phase, and propose a general phase\ndiagram for this system.",
        "positive": "Modeling of Negative Capacitance of Ferroelectric Capacitors as a\n  Non-Quasi Static Effect: Pulse-based studies of ferroelectric capacitor systems have been used by\nseveral groups to experimentally probe the mechanisms of apparent negative\ncapacitance. In this paper, the behavior of such systems is modeled through\nSPICE simulation with a delayed-response Preisach model, and the results are\ncompared to available data. It is found that a simple ferroelectric domain\ndelay model can explain much of the observed behavior, capturing the\nqualitatively different effects of bipolar and unipolar switching, as well as\nthe voltage dependence of said switching. The observed behavior and its\nmodeling suggests that the observed negative capacitance is in fact associated\nwith ferroelectric switching, and its presence is highly sensitive to the\nswitching frequency and other details of the ferroelectric system."
    },
    {
        "anchor": "Low-noise conditional operation of singlet-triplet coupled quantum dot\n  qubits: We theoretically study the influence of charge noise on a controlled phase\ngate, implemented using two proximal double quantum dots coupled\nelectrostatically. Using the configuration interaction method, we present a\nfull description of the conditional control scheme and quantitatively calculate\nthe gate error arising from charge fluctuations. Our key finding is that the\nexistence of noise-immune sweet spots depends on not only the energy detuning\nbut also the device geometry. The conditions for sweet spots with minimal\ncharge noise are predicted analytically and verified numerically. Going beyond\nthe simple sweet-spot concept we demonstrate the existence of other optimal\nsituations for fast and low-noise singlet-triplet two-qubit gates.",
        "positive": "Current cross-correlations and waiting time distributions in Andreev\n  transport through Cooper pair splitters based on triple quantum dots: We study the spin-resolved subgap transport in a triple quantum-dot system\ncoupled to one superconducting and two ferromagnetic leads. We examine the\nAndreev processes in the parallel and antiparallel alignments of ferromagnets\nmagnetic moments in both the linear and nonlinear response regimes. The\nemphasis is put on the analysis of the current cross-correlations between the\ncurrents flowing through the left and right arms of the device and relevant\nelectron waiting time distributions. We show that both quantities can give an\nimportant insight into the subgap transport processes and their analysis can\nhelp optimizing the system parameters for achieving the considerable Andreev\ncurrent and efficient Cooper pair splitting. Strong positive values of\ncross-correlations are associated with the presence of tunneling processes\nenhancing the Cooper pair splitting efficiency, while short waiting times for\nelectrons tunneling through distinct ferromagnetic contacts indicate fast\nsplitting of emitted Cooper pairs. In particular, we study two detuning schemes\nand show that antisymmetric shift of side quantum dots energy levels is\nfavorable for efficient Cooper pair splitting. The analysis of spin-resolved\nwaiting time distributions supports the performance enhancement due to the\npresence of ferromagnetic contacts, which is in particular revealed for short\ntimes. Finally, we consider the effect of changing the inter-dot hopping\namplitude and predict that strong inter-dot correlations lead to a reduction of\nAndreev transport properties in low-bias limit."
    },
    {
        "anchor": "Unconventional Superconductivity in Double Quantum Dots: The formation of electron pairs is a prerequisite of superconductivity. The\nfermionic nature of electrons yields four classes of superconducting\ncorrelations with definite symmetry in spin, space and time. Here, we suggest\ndouble quantum dots coupled to conventional s-wave superconductors in the\npresence of inhomogeneous magnetic fields as a model system exhibiting\nunconventional pairing. Due to their small number of degrees of freedom,\ntunable by gate voltages, quantum-dot systems provide an ideal tool to gain\nfundamental insight in unconventional pairing. We propose two detection schemes\nfor unconventional superconductivity, based on either Josephson or Andreev\nspectroscopy.",
        "positive": "Heat Conductance of the Quantum Hall Bulk: The Quantum Hall Effect (QHE) is a prototypical realization of a topological\nstate of matter. It emerges from a subtle interplay between topology,\ninteractions, and disorder. The disorder enables the formation of localized\nstates in the bulk that stabilize the quantum Hall states with respect to the\nmagnetic field and carrier density. Still, the details of the localized states\nand their contribution to transport remain beyond the reach of most\nexperimental techniques. Here, we describe an extensive study of the bulk's\nheat conductance. Using a novel 'multi-terminal' short device (on a scale of\n$10 \\mu m$), we separate the longitudinal thermal conductance, $\\kappa_{xx}T$\n(due to bulk's contribution), from the topological transverse value\n$\\kappa_{xy}T$, by eliminating the contribution of the edge modes. When the\nmagnetic field is tuned away from the conductance plateau center, the localized\nstates in the bulk conduct heat efficiently ($\\kappa_{xx}T \\propto T$), while\nthe bulk remains electrically insulating. Fractional states in the first\nexcited Landau level, such as the $\\nu=7/3$ and $\\nu=5/2$, conduct heat\nthroughout the plateau with a finite $\\kappa_{xx} T$. We propose a theoretical\nmodel that identifies the localized states as the cause of the finite heat\nconductance, agreeing qualitatively with our experimental findings."
    },
    {
        "anchor": "Topological features of ground states and topological solitons in\n  generalized Su-Schrieffer-Heeger models using generalized time-reversal,\n  particle-hole, and chiral symmetries: Topological phases and their topological features are enriched by the\nfundamental time-reversal, particle-hole, and chiral as well as crystalline\nsymmetries. While one-dimensional (1D) generalized Su-Schrieffer-Heeger (SSH)\nsystems show various topological phenomena such as topological solitons and\ntopological charge pumping, it remains unclear how such symmetry protects and\nrelates such topological phenomena. Here we show that the generalized\ntime-reversal, particle-hole, and chiral symmetry operators consistently\nexplain not only the symmetry transformation properties between the ground\nstates but also the topological features of the topological solitons in\nprototypical quasi-1D systems such as the SSH, Rice-Mele, and double-chain\nmodels. As a consequence, we classify generalized essential operators into\nthree groups: Class I and class II operators connect ground states in between\nafter spontaneous symmetry breaking while class III operators give the\ngeneralized particle-hole and chiral symmetries to ground states. Furthermore,\nclass I operators endow the equivalence relation between topological solitons\nwhile class II and III operators do the particle-hole relations. Finally, we\ndemonstrate three distinct types of topological charge pumping and soliton\nchirality from the viewpoint of class I, II, and III operators. We build a\ngeneral framework to explore the topological features of the generalized 1D\nelectronic system, which can be easily applied in various condensed matter\nsystems as well as photonic crystal and cold atomic systems.",
        "positive": "Modeling contact formation between atomic-sized gold tips via molecular\n  dynamics: The formation and rupture of atomic-sized contacts is modelled by means of\nmolecular dynamics simulations. Such nano-contacts are realized in scanning\ntunnelling microscope and mechanically controlled break junction experiments.\nThese instruments routinely measure the conductance across the nano-sized\nelectrodes as they are brought into contact and separated, permitting\nconductance traces to be recorded that are plots of conductance versus the\ndistance between the electrodes. One interesting feature of the conductance\ntraces is that for some metals and geometric configurations a jump in the value\nof the conductance is observed right before contact between the electrodes, a\nphenomenon known as jump-to-contact. This paper considers, from a computational\npoint of view, the dynamics of contact between two gold nano-electrodes.\nRepeated indentation of the two surfaces on each other is performed in two\ncrystallographic orientations of face-centred cubic gold, namely (001) and\n(111). Ultimately, the intention is to identify the structures at the atomic\nlevel at the moment of first contact between the surfaces, since the value of\nthe conductance is related to the minimum cross-section in the contact region.\nConductance values obtained in this way are determined using first principles\nelectronic transport calculations, with atomic configurations taken from the\nmolecular dynamics simulations serving as input structures."
    },
    {
        "anchor": "Reversing non-local transport through a superconductor by\n  electromagnetic excitations: Superconductors connected to normal metallic electrodes at the nanoscale\nprovide a potential source of non-locally entangled electron pairs. Such states\nwould arise from Cooper pairs splitting into two electrons with opposite spins\ntunnelling into different leads. In an actual system the detection of these\nprocesses is hindered by the elastic transmission of individual electrons\nbetween the leads, yielding an opposite contribution to the non-local\nconductance. Here we show that electromagnetic excitations on the\nsuperconductor can play an important role in altering the balance between these\ntwo processes, leading to a dominance of one upon the other depending on the\nspatial symmetry of these excitations. These findings allow to understand some\nintriguing recent experimental results and open the possibility to control\nnon-local transport through a superconductor by an appropriate design of the\nexperimental geometry.",
        "positive": "Spin Torque Dynamics with Noise in Magnetic Nano-System: We investigate the role of equilibrium and nonequilibrium noise in the\nmagnetization dynamics on mono-domain ferromagnets. Starting from a microscopic\nmodel we present a detailed derivation of the spin shot noise correlator. We\ninvestigate the ramifications of the nonequilibrium noise on the spin torque\ndynamics, both in the steady state precessional regime and the spin switching\nregime. In the latter case we apply a generalized Fokker-Planck approach to\nspin switching, which models the switching by an Arrhenius law with an\neffective elevated temperature. We calculate the renormalization of the\neffective temperature due to spin shot noise and show that the nonequilibrium\nnoise leads to the creation of cold and hot spot with respect to the noise\nintensity."
    },
    {
        "anchor": "Graphite superlubricity enabled by triboinduced nanocontacts: Colloidal probe Atomic Force Microscopy allows to explore sliding states of\nvanishing friction, i.e. superlubricity, in mesoscopic graphite contacts.\nSuperlubricity is known to appear upon formation of a triboinduced transfer\nlayer, originated by material transfer of graphene flakes from the graphitic\nsubstrate to the colloidal probe. Previous studies suggest that friction\nvanishes due to crystalline incommensurability at the newly formed interface.\nHowever this picture still lacks several details, such as the roles of the\ntribolayer roughness and of loading conditions. Hereafter we gain deeper\ninsight into the tribological response of micrometric silica beads sliding on\ngraphite under ambient conditions. We show that the tribotransferred flakes\nbehave as lubricious nanoasperities with a twofold role. First, they decrease\nthe silica-graphite true contact area, in fact causing a breakdown of adhesion\nand friction by one order of magnitude. Second, they govern mechanical\ndissipation through the specific energy landscape experienced by the\ntopographically-highest triboinduced nanoasperity. Remarkably, such contact\njunctions can undergo a load-driven atomic-scale transition from continuous\nsuperlubric sliding to dissipative stick-slip, that agrees with the\nsingle-asperity Prandtl-Tomlinson model. Superlubricity in mesoscopic\nsilica-graphite junctions may therefore arise from the load-controlled\ncompetition between interfacial crystalline incommensurability and contact\npinning effects at one dominant nanoasperity.",
        "positive": "Spin Diode Based on Fe/MgO Double Tunnel Junction: We demonstrate a spin diode consisting of a semiconductor free nano-scale\nFe/MgO-based double tunnel junction. The device exhibits a near perfect\nspin-valve effect combined with a strong diode effect. The mechanism consistent\nwith our data is resonant tunneling through discrete states in the middle\nferromagnetic layer sandwiched by tunnel barriers of different spin-dependent\ntransparency. The observed magneto-resistance is record high, ~4000%,\nessentially making the structure an on/off spin-switch. This, combined with the\nstrong diode effect, ~100, offers a new device that should be promising for\nsuch technologies as magnetic random access memory and re-programmable logic."
    },
    {
        "anchor": "Phenomenology of the 0.7 conductance feature: We describe a phenomenological model for the conductance feature near $0.7\n\\times 2e^2/h$ that occurs in quantum point contacts. We focus on the\ntransconductance at finite source-drain bias and contrast our model with the\nresults expected from a single-particle picture. Good agreement is seen in\ncomparing the model with experimental data, taken on ultra-low-disorder GaAs\ninduced electron systems. Although simple, our phenomenology suggests important\nboundary conditions for an underlying microscopic theory.",
        "positive": "Impact of complex adatom-induced interactions on quantum spin Hall\n  phases: Adsorbate engineering offers a seemingly simple approach to tailor spin-orbit\ninteractions in atomically thin materials and thus to unlock the much\nsought-after topological insulating phases in two dimensions. However, the\nobservation of an Anderson topological transition induced by heavy adatoms has\nproved extremely challenging despite substantial experimental efforts. Here, we\npresent a multi-scale approach combining advanced first-principles methods and\naccurate single-electron descriptions of adatom-host interactions using\ngraphene as a prototypical system. Our study reveals a surprisingly complex\nstructure in the interactions mediated by random adatoms, including hitherto\nneglected hopping processes leading to strong valley mixing. We argue that the\nunexpected intervalley scattering strongly impacts the ground state at low\nadatom coverage, which would provide a compelling explanation for the absence\nof a topological gap in recent experimental reports. Our conjecture is\nconfirmed by real-space Chern number calculations and large-scale quantum\ntransport simulations in disordered samples. This resolves an important\ncontroversy and suggests that a detectable topological gap can be achieved by\nengineering the spatial range of spin-orbit interactions."
    },
    {
        "anchor": "Amplitude dependence of image quality in atomically-resolved bimodal\n  atomic microscopy: In bimodal FM-AFM, two flexural modes are excited simultaneously. The total\nvertical oscillation deflection range of the tip is the sum of the peak-to-peak\namplitudes of both flexural modes (sum amplitude). We show atomically resolved\nimages of KBr(100) in ambient conditions in bimodal AFM that display a strong\ncorrelation between image quality and sum amplitude. When the sum amplitude\nbecomes larger than about 200 pm, the signal-to-noise ratio (SNR) is\ndrastically decreased. We propose this is caused by the temporary presence of\none or more water layers in the tip-sample gap. These water layers screen the\nshort range interaction and must be displaced with each oscillation cycle.\nFurther decreasing the sum amplitude, however, causes a decrease in SNR.\nTherefore, the highest SNR in ambient conditions is achieved when the sum\namplitude is slightly less than the thickness of the primary hydration layer.",
        "positive": "Klein-tunneling-enhanced directional coupler for Dirac electron wave in\n  graphene: Using the coupled-mode theory in guided-wave optics and electronics, we\nexplore a directional coupling structure composed of two parallel waveguides\nelectrostatically induced by the split-gate technique in bulk graphene. Our\nresults show that Klein tunneling can greatly enhance the coupling strength of\nthe structure. By adjusting a gate voltage, the probability density of Dirac\nelectron wave function initially in one waveguide can be completely transferred\ninto the other waveguide within several hundred nanometers. Our findings could\nnot only lead to functional coherent coupling devices for quantum-based\nelectronic signal processing and on-chip device integration in graphene, but\nalso shrink the size of the devices to facilitate the fabrication of\ngraphene-based large-scale integrated logic circuits."
    },
    {
        "anchor": "Needle in a haystack: efficiently finding atomically defined quantum\n  dots for electrostatic force microscopy: The ongoing development of single electron, nano and atomic scale\nsemiconductor devices would benefit greatly from a characterization tool\ncapable of detecting single electron charging events with high spatial\nresolution, at low temperature. In this work, we introduce a novel Atomic Force\nMicroscope (AFM) instrument capable of measuring critical device dimensions,\nsurface roughness, electrical surface potential, and ultimately the energy\nlevels of quantum dots and single electron transistors in ultra miniaturized\nsemiconductor devices. Characterization of nanofabricated devices with this\ntype of instrument presents a challenge: finding the device. We therefore also\npresent a process to efficiently find a nanometre size quantum dot buried in a\n$10 \\times 10~\\text{mm}^2$ silicon sample using a combination of optical\npositioning, capacitive sensors and AFM topography in vacuum.",
        "positive": "Spin-orbit interaction in bent carbon nanotubes: resonant spin\n  transitions: We develop an effective tight-binding Hamiltonian for spin-orbit (SO)\ninteraction in bent carbon nanotubes (CNT) for the electrons forming the $\\pi$\nbonds between the nearest neighbor atoms. We account for the bend of the CNT\nand the intrinsic spin-orbit interaction which introduce mixing of $\\pi$ and\n$\\sigma$ bonds between the $p_z$ orbitals along the CNT. The effect contributes\nto the main origin of the SO coupling--the folding of the graphene plane into\nthe nanotube. We discuss the bend-related contribution of the SO coupling for\nresonant single-electron spin and charge transitions in a double quantum dot.\nWe report that although the effect of the bend-related SO coupling is weak for\nthe energy spectra, it produces a pronounced increase of the spin transition\nrates driven by an external electric field. We find that spin-flipping\ntransitions driven by alternate electric fields have usually larger rates when\naccompanied by charge shift from one dot to the other. Spin-flipping transition\nrates are non-monotonic functions of the driving amplitude since they are\nmasked by stronger spin-conserving charge transitions. We demonstrate that the\nfractional resonances--counterparts of multiphoton transitions for atoms in\nstrong laser fields--occurring in electrically controlled nanodevices already\nat moderate ac amplitudes--can be used to maintain the spin-flip transitions."
    },
    {
        "anchor": "Quantum dots investigated with charge detection techniques: The detection of the quantum dot charge state using a quantum point contact\ncharge detector has opened a new exciting route for the investigation of\nquantum dot devices in recent years. In particular, time-resolved charge\ndetection allowed the precise measurement of quantum dot shot noise at\nsub-femtoampere current levels, and the full counting statistics of the\ncurrent. The technique can be applied to different material systems and holds\npromise for the future application in quantum dot based quantum information\nprocessing implementations. We review recent experiments employing this charge\ndetection technique, including the self-interference of individual electrons\nand back-action phenomena.",
        "positive": "Phase driving hole spin qubits: The spin-orbit interaction in spin qubits enables spin-flip transitions,\nresulting in Rabi oscillations when an external microwave field is resonant\nwith the qubit frequency. Here, we introduce an alternative driving mechanism\nof hole spin qubits, where a far-detuned oscillating field couples to the qubit\nphase. Phase driving at radio frequencies, orders of magnitude slower than the\nmicrowave qubit frequency, induces highly non-trivial spin dynamics, violating\nthe Rabi resonance condition. By using a qubit integrated in a silicon fin\nfield-effect transistor (Si FinFET), we demonstrate a controllable suppression\nof resonant Rabi oscillations, and their revivals at tunable sidebands. These\nsidebands enable alternative qubit control schemes using global fields and\nlocal far-detuned pulses, facilitating the design of dense large-scale qubit\narchitectures with local qubit addressability. Phase driving also decouples\nRabi oscillations from noise, an effect due to a gapped Floquet spectrum and\ncan enable Floquet engineering high-fidelity gates in future quantum\nprocessors."
    },
    {
        "anchor": "Molecular Conductance: Chemical Trends of Anchoring Groups: Combining density functional theory calculations for molecular electronic\nstructure with a Green function method for electron transport, we calculate\nfrom first principles the molecular conductance of benzene connected to two Au\nleads through different anchoring atoms -- S, Se, and Te. The relaxed atomic\nstructure of the contact, different lead orientations, and different adsorption\nsites are fully considered. We find that the molecule-lead coupling, electron\ntransfer, and conductance all depend strongly on the adsorption site, lead\norientation, and local contact atomic configuration. For flat contacts the\nconductance decreases as the atomic number of the anchoring atom increases,\nregardless of the adsorption site, lead orientation, or bias. For small bias\nthis chemical trend is, however, dependent on the contact atomic configuration:\nan additional Au atom at the contact with the (111) lead changes the best\nanchoring atom from S to Se although for large bias the original chemical trend\nis recovered.",
        "positive": "Enhanced Dirac node separation in strained Cd3As2 topological semimetal: In topological semimetals, nodes appear at symmetry points in the Brillouin\nzone as a result of band inversion, and yield quasi-relativistic massless\nfermions at low energies. Cd3As2 is a three-dimensional topological semimetal\nthat hosts two Dirac cones responsible for a variety of quantum phenomena. In\nthis work, we demonstrate the strain tuning of the Dirac nodes of Cd3As2\nthrough a combination of magnetooptical infrared spectroscopy and\nhigh-resolution X-ray diffraction studies performed on epitaxial films. In\nthese thin films, we observe a giant enhancement of the node separation in\nmomentum space by close to a factor of 4. A combination of experimental\nmeasurements and theoretical modelling allows relate the origin of this\nenhancement to a strengthening of the topological band inversion driven by\nlattice strain. Our results demonstrate how strain can be used as a knob to\ntune the topological properties of semimetals and to potentially enhance their\nperformance and response for various applications."
    },
    {
        "anchor": "Insulating state and giant non-local response in an InAs/GaSb quantum\n  well in the quantum Hall regime: We present transport measurements performed in InAs/GaSb double quantum\nwells. At the electron-hole crossover tuned by a gate voltage, a strong\nincrease in the longitudinal resistivity is observed with increasing\nperpendicular magnetic field. Concomitantly with a local resistance exceeding\nthe resistance quantum by an order of magnitude, we find a pronounced non-local\nresistance signal of almost similar magnitude. The co-existence of these two\neffects is reconciled in a model of counter-propagating and dissipative quantum\nHall edge channels providing backscattering, shorted by a residual bulk\nconductivity.",
        "positive": "Infinite magnetoresistance of magnetic multilayers: We examine transport properties of a magnetic superlattice with current\nperpendicular to the planes. In the limit that the phase-breaking and spin flip\nscattering lengths are greater than the system size, a multiple-scattering\napproach is used to calculate the 4-probe conductance. We show that by tuning\nthe strength of tunnel barriers placed between the current and voltage probes\ngiant magnetoresistance ratios of arbitrary strength and size are achievable."
    },
    {
        "anchor": "Decoherence of the Kondo Singlet via a Quantum Point Contact Detector: We investigate the effect of the charge state measurement of the Kondo\nsinglet for a quantum dot transistor via a capacitively coupled quantum point\ncontact detector. By employing the variational ansatz for the singlet ground\nstate of the quantum dot combined with the density matrix formulation for the\ncoupled system, we show that the coherent Kondo singlet is destroyed by the\nphase-sensitive as well as the magnitude-sensitive detection in the\ntransmission/reflection coefficients at the quantum point contact. We argue\nthat the phase-sensitive component of the decoherence rate may explain the\nanomalous features observed in a recent experiment by Avinun-Kalish {\\em et\nal.} (Phys. Rev. Lett. {\\bf 92}, 156801 (2004)). We also discuss the\ncorrelations of the shot noise at the quantum point contact detector and the\ndecoherence in the quantum dot.",
        "positive": "Nonlinear helicity anomalies in the cyclotron resonance photoresistance\n  of two-dimensional electron systems: Our studies of the cyclotron resonance (CR) photoresistance in GaAs-based\ntwo-dimensional electron systems (2DES) reveal an anomalously low sensitivity\nto the helicity of the incoming circularly polarized terahertz radiation. We\nfind that this anomaly is strongly intensity dependent, and the ratio of the\nlow-temperature photoresistance signals for the CR-active (CRA) and CR-inactive\n(CRI) polarities of magnetic field increases with lowering power, but,\nnevertheless, remains substantially lower than expected from conventional\ntheory assuming interaction of the plane electromagnetic wave with the uniform\n2DES. Our analysis shows that all data can be well described by the nonlinear\nCR-enhanced electron gas heating in both CRA and CRI regimes. This description,\nhowever, requires a source of anomalous absorption of radiation in the CRI\nregime. It can stem from evanescent electromagnetic fields originating from the\nnear-field diffraction within or in the vicinity of the quantum well hosting\nthe 2DES."
    },
    {
        "anchor": "Interaction of graphene monolayer with ultrashort laser pulse: We study the interaction of graphene with ultrashort few femtosecond long\noptical pulse. For such a short pulse, the electron dynamics is coherent and is\ndescribed within the tight-binding model of graphene. The interaction of\noptical pulse with graphene is determined by strong wave vector dependence of\nthe interband dipole matrix elements, which are singular at the Dirac points of\ngraphene. The electron dynamics in optical pulse is highly irreversible with\nlarge residual population of the conduction band. The residual conduction band\npopulation as a function of the wave vector is nonuniform with a few localized\nspots of high conduction band population. The spots are located near the Dirac\npoints and the number of spots depends on the pulse intensity. The optical\npulse propagating through graphene layer generates finite transferred charge,\nwhich, as a function of pulse intensity, changes its sign. At small pulse\nintensity, the charge is transferred in the direction of the pulse maximum,\nwhile at large pulse intensity, the direction of the charge transfer is\nopposite to the direction of pulse maximum. This property opens unique\npossibility of controlling the direction of the charge transfer by variation of\nthe pulse intensity.",
        "positive": "Chiral sound waves in strained Weyl semimetals: We show that a strained wire of a Weyl semimetal supports a new type of\ngapless excitation, the chiral sound wave (CSW). It is a longitudinal charge\ndensity wave analog to the chiral magnetic wave predicted in the quark-gluon\nplasma but driven by an elastic axial pseudo-magnetic field. It involves the\naxial-axial-axial contribution to the chiral anomaly which couples the chiral\ncharge density to the elastic axial gauge field. The chiral sound is\nunidirectional: it propagates along the elastic magnetic field and not in the\nopposite direction. The CSW may propagate for long distances as it does not\ncouple directly to quickly dissipating electromagnetic plasmons, while its\ndamping is controlled by the slow chirality flip rate. We propose an\nexperimental setup to directly detect the chiral sound, which is excited by\nmechanical vibrations of the crystal lattice in the GHz frequency range. Our\nfindings contribute to a new trend, the chiral acoustics, in strained Weyl\nsemimetals."
    },
    {
        "anchor": "Berry curvature dipole senses topological transition in a moir\u00e9\n  superlattice: Topological aspects of electron wavefunction play a crucial role in\ndetermining the physical properties of materials. Berry curvature and Chern\nnumber are used to define the topological structure of electronic bands. While\nBerry curvature and its effects in materials have been studied, detecting\nchanges in the topological invariant, Chern number, is challenging. In this\nregard, twisted double bilayer graphene (TDBG) has emerged as a promising\nplatform to gain electrical control over the Berry curvature hotspots and the\nvalley Chern numbers of its flat bands. In addition, strain induced breaking of\nthe three-fold rotation (C3) symmetry in TDBG, leads to a non-zero first moment\nof Berry curvature called the Berry curvature dipole (BCD), which can be sensed\nusing nonlinear Hall (NLH) effect. We reveal, using TDBG, that the BCD detects\ntopological transitions in the bands and changes its sign. In TDBG, the\nperpendicular electric field tunes the valley Chern number and the BCD\nsimultaneously allowing us a tunable system to probe the physics of topological\ntransitions. Furthermore, we find hysteresis of longitudinal and NLH responses\nwith electric field that can be attributed to switching of electric\npolarization in moir\\'e systems. Such a hysteretic response holds promise for\nnext-generation Berry curvature-based memory devices. Probing topological\ntransitions, as we show, can be emulated in other 3D topological systems.",
        "positive": "Interplay of Landau quantization and interminivalley scatterings in a\n  weakly coupled moir\u00e9 superlattice: Double layer quantum systems are promising platforms for realizing novel\nquantum phases. Here, we report a study of quantum oscillations (QOs) in a\nweakly coupled double layer system, composed of a large angle twisted double\nbilayer graphene (TDBG). We observe two different QOs at low temperature, one\nwith a periodicity in carrier density (n), i.e. Shubnikov de Haas oscillation\n(SdHO) due to Landau quantization, and the other one in displacement field (D),\nresulting a grid pattern. We quantify the interlayer coupling strength by\nmeasuring the interlayer capacitance from the grid pattern with a capacitance\nmodel, revealing an electron hole asymmetry. At high temperature when SdHO are\nthermal smeared, we observe resistance peaks when LLs from two minivalleys in\nthe moir\\'e Brillion zone are aligned, regardless of carrier density;\neventually, it results in a two fold increase of oscillating frequency in D,\nserving as a smoking gun evidence of the magneto intersubband oscillations\n(MISO) in a double layer system. The temperature dependence of MISO suggests\nelectron-electron interaction between two minivalleys play a crucial rule in\nthe scattering, and the scattering times obtained from MISO thermal damping are\nfound to be correlated with the interlayer coupling strength. Our study reveals\nan intriguing interplay among Landau quantization, moir\\'e band structure, and\nscatterings."
    },
    {
        "anchor": "Thermoelectric transport of mesoscopic conductors coupled to voltage and\n  thermal probes: We investigate basic properties of the thermopower (Seebeck coefficient) of\nphase-coherent conductors under the influence of dephasing and inelastic\nprocesses. Transport across the system is caused by a voltage bias or a thermal\ngradient applied between two terminals. Inelastic scattering is modeled with\nthe aid of an additional probe acting as an ideal potentiometer and\nthermometer. We find that inelastic scattering reduces the conductor's\nthermopower and, more unexpectedly, generates a magnetic-field asymmetry in the\nSeebeck coefficient. The latter effect is shown to be a higher-order effect in\nthe Sommerfeld expansion. We discuss our result using two illustrative\nexamples. First, we consider a generic mesoscopic system described within\nrandom matrix theory and demonstrate that thermopower fluctuations disappear\nquickly as the number of probe modes increases. Second, the asymmetry is\nexplicitly calculated in the quantum limit of a ballistic microjunction. We\nfind that asymmetric scattering strongly enhances the effect and discuss its\ndependence on temperature and Fermi energy.",
        "positive": "Electrostatic detection of Shubnikov-de-Haas oscillations in bilayer\n  graphene by Coulomb resonances in gate-defined quantum dots: A gate-defined quantum dot in bilayer graphene is utilized as a sensitive\nelectrometer for probing the charge density of its environment. Under the\ninfluence of a perpendicular magnetic field, the charge carrier density of the\nchannel region next to the quantum dot oscillates due to the formation of\nLandau levels. This is experimentally observed as oscillations in the\ngate-voltage positions of the Coulomb resonances of the nearby quantum dot.\nFrom the frequency of the oscillations, we extract the charge carrier density\nin the channel and from the amplitude the shift of the quantum dot potential.\nWe compare these experimental results with an electrostatic simulation of the\ndevice and find good agreement."
    },
    {
        "anchor": "Emerging nonequilibrium bound state in spin-current-local-spin\n  scattering: Magnetization reversal is a well-studied problem with obvious applicability\nin computer hard-drives. One can accomplish a magnetization reversal in at\nleast one of two ways: application of a magnetic field, or through a spin\ncurrent. The latter is more amenable to a fully quantum mechanical analysis. We\nformulate and solve the problem whereby a spin current interacts with a\nferromagnetic Heisenberg spin chain, to eventually reverse the magnetization of\nthe chain. Spin-flips are accomplished through both elastic and inelastic\nscattering. A consequence of the inelastic scattering channel, when it is no\nlonger energetically possible, is the occurrence of a new entity: a\nnon-equilibrium bound state (NEBS), which is an emergent property of the\ncoupled local plus itinerant spin system. For certain definite parameter values\nthe itinerant spin lingers near the local spins for some time, before\neventually leaking out as an outwardly diffusing state. This phenomenon results\nin novel spin-flip dynamics and filtering properties for this type of system.",
        "positive": "Spin-Hall Magnetoresistance in Platinum on Yttrium Iron Garnet:\n  Dependence on platinum thickness and in-plane/out-of-plane magnetization: The occurrence of Spin-Hall Magnetoresistance (SMR) in platinum (Pt) on top\nof yttrium iron garnet (YIG) has been investigated, for both in-plane and\nout-of-plane applied magnetic fields and for different Pt thicknesses [3, 4, 8\nand 35nm]. Our experiments show that the SMR signal directly depends on the\nin-plane and out-of-plane magnetization directions of the YIG. This confirms\nthe theoretical description, where the SMR occurs due to the interplay of\nspin-orbit interaction in the Pt and spin-mixing at the YIG/Pt interface.\nAdditionally, the sensitivity of the SMR and spin pumping signals on the YIG/Pt\ninterface conditions is shown by comparing two different deposition techniques\n(e-beam evaporation and dc sputtering)."
    },
    {
        "anchor": "Bag boundaries for quasispinor confinement within nanolanes on a\n  graphene sheet: We revisit the problem of bag boundary conditions within a field-theoretic\napproach to study confinement of massless Dirac quasispinors in monolayer\ngraphene. While no-flux bag boundaries have previously been used to model\nlattice termination sites in graphene nanoribbons, we consider a generalized\nsetting in which the confining boundaries are envisaged as arbitrary straight\nlines drawn across a graphene sheet and the quasispinor currents are allowed to\npartially permeate (leak) through such boundaries. We specifically focus on\nrectangular nanolanes defined as areas confined between a pair of parallel\nlines at arbitrary separation on an unbounded lattice. We show that such\nnanolanes exhibit a considerable range of bandgap tunability depending on their\nwidths and armchair, zigzag or intermediate orientation. The case of\nnanoribbons can be derived as a special limit from the nanolane model. In this\ncase, we clarify certain inconsistencies in previous implementations of no-flux\nbag boundaries and show that the continuum approach reproduces the\ntight-binding bandgaps accurately (within just a few percent in relative\ndeviation) even as the nanoribbon width is decreased to just a couple of\nlattice spacings. This accentuates the proper use of boundary conditions when\nfield-theoretic approaches are applied to graphene systems.",
        "positive": "Charge Sensing in Intrinsic Silicon Quantum Dots: We report charge sensing measurements on a silicon quantum dot (QD) with a\nnearby silicon single electron transistor (SET) acting as an electrometer. The\ndevices are electrostatically formed in bulk silicon using surface gates. We\nshow that as an additional electron is added onto the quantum dot, a charge is\ninduced on the SET of approximately 0.2e. These measurements are performed in\nthe many electron regime, where we can count in excess of 20 charge additions\nonto the quantum dot."
    },
    {
        "anchor": "Phase separation from electron confinement at oxide interfaces: Oxide heterostructures are of great interest both for fundamental and\napplicative reasons. In particular the two-dimensional electron gas at the\nLaAlO$_3$/SrTiO$_3$ or LaTiO$_3$/SrTiO$_3$ interfaces displays many different\nphysical properties and functionalities. However there are clear indications\nthat the interface electronic state is strongly inhomogeneous and therefore it\nis crucially relevant to investigate possible intrinsic electronic mechanisms\nunderlying this inhomogeneity. Here the electrostatic potential confining the\nelectron gas at the interface is calculated self-consistently, finding that the\nelectron confinement at the interface may induce phase separation, to avoid a\nthermodynamically unstable state with a negative compressibility. This provides\na generic robust and intrinsic mechanism for the experimentally observed\ninhomogeneous character of these interfaces.",
        "positive": "Modeling Photocurrent Spectra of\n  In$_{0.91}$Ga$_{0.09}$N/In$_{0.4}$Ga$_{0.6}$N Disk-in-Wire Photodiode on\n  Silicon for $1.3$ $\u03bc$m $-$ $1.55$ $\u03bc$m Operation: This work reports comprehensive theoretical modeling of photocurrent spectra\ngenerated by an In$_{0.91}$Ga$_{0.09}$N/In$_{0.4}$Ga$_{0.6}$N disk-in-wire\nphotodiode. The strain distribution is calculated by valence-force-field (VFF)\nmodel, while a realistic band structure of the InN/InGaN heterostructure is\nincorporated using an eight-band effective bond-orbital model (EBOM) with\nspin-orbit coupling neglected. The electrostatic potential is obtained from\nself-consistent calculation employing the non-equilibrium Green's function\n(NEGF) method. With the strain distribution and band profile determined, a\nmulti-band transfer-matrix method (TMM) is used to calculate the tunneling\ncoefficients of optically-pumped carriers in the absorbing region. The\nphotocurrent spectra contributed by both single-photon absorption (SPA) and\ntwo-photon absorption (TPA) are calculated. The absorption coefficient is\nweighted by the carrier tunneling rate and the photon density-of-state (DOS) in\nthe optical cavity formed in the nanowire region to produce the photocurrent.\nThe calculated photocurrent spectra is in good agreement with experimental\ndata, while physical mechanisms for the observed prominent peaks are identified\nand investigated."
    },
    {
        "anchor": "Fractional Quantum Hall Effect and Wigner Crystal of Two-Flux Composite\n  Fermions: In two-dimensional electron systems confined to GaAs quantum wells, as a\nfunction of either tilting the sample in magnetic field or increasing density,\nwe observe multiple transitions of the fractional quantum Hall states (FQHSs)\nnear filling factors $\\nu=3/4$ and 5/4. The data reveal that these are\nspin-polarization transitions of interacting two-flux composite Fermions, which\nform their own FQHSs at these fillings. The fact that the reentrant integer\nquantum Hall effect near $\\nu=4/5$ always develops following the transition to\nfull spin polarization of the $\\nu=4/5$ FQHS strongly links the reentrant phase\nto a pinned \\emph{ferromagnetic} Wigner crystal of two-flux composite Fermions.",
        "positive": "Electrical conductance of atomic contacts in liquid environments: We present measurements of the electrical conductance $G$ at room temperature\nof mechanically controllable break junctions (MCBJ) fabricated from Au in\ndifferent solvents (octane, DCM, DMSO, and toluene) and compare with\nmeasurements in air and vacuum. In the high conductance regime $G \\agt\nG_0=2e^2/h$, the environment plays a minor role, as proven by the measured\nconductance histograms, which do not depend on the environment. In contrast,\nthe environment significantly affects the electrical properties in the low\nconductance (tunneling) regime {$G << G_0$}. Here, we observe a systematic and\nreproducible lowering of the tunneling barrier height $\\phi$. At shorter\ndistances, a transition to a strongly suppressed apparent barrier height is\nobserved in octane, providing evidence for the layering of solvent molecules at\nsmall inter-electrodes separations. The presented experimental configuration\noffers interesting perspectives for the electrical characterization of single\nmolecules in a controlled environment."
    },
    {
        "anchor": "Conductivity magnetooscillations in 2D electron-impurity system under\n  microwave irradiation: role of magnetoplasmons: It is developed a many-electron approach to explain the recently observed\nconductivity magnetooscillations in very high mobility 2D electron systems\nunder microwave irradiation. For the first time a theory takes into account the\nmicrowave-induced renormalization of the screened impurity potential. As a\nresult this potential has singular, dynamic and non-linear in electric field\nnature. That changes the picture of scattering of electrons at impurities in a\n``clean'' 2D system essentially: for appearence of the rectified dissipative\ncurrent responsible are excitations of 2D magnetoplasmons rather than\none-electron transitions between Landau levels. In a ``dirty'' 2D system the\nrole of electron-electron interaction diminishes, so the collective excitations\ncease to exist, and our results turn into the well-known ones, which were\nobtained in the one-electron approach.",
        "positive": "Generation of spin-triplet Cooper pairs via a canted antiferromagnet: Spinful triplet Cooper pairs can be generated from their singlet counterparts\navailable in a conventional superconductor (S) using two or more noncollinear\nmagnetic moments, typically contributed by different magnets in a multilayered\nheterostructure. Here, we theoretically demonstrate that an S interfaced with a\ncanted antiferromagnet (AF) harbors spinful triplet Cooper pairs capitalizing\non the intrinsic noncollinearity between the two AF sublattice magnetizations.\nAs the AF canting can be controlled by an applied field, our work proposes a\nsimple bilayer structure that admits controllable generation of spin-triplet\nCooper pairs. Employing the Bogoliubov-de Gennes framework, we delineate the\nspatial dependence of the spin-triplet correlations. We further evaluate the\nsuperconducting critical temperature as a function of the AF canting, which\nprovides one experimental observable associated with the emergence of these\ntriplet correlations."
    },
    {
        "anchor": "Analysis of radiation effect on the threshold voltage of flash memory\n  device: Flash memory experiences adverse effects due to radiation. These effects can\nbe raised in terms of doping, feature size, supply voltages, layout, shielding.\nThe the operating point shift of the device forced to enter the\nlogically-undefined region and cause upset and data errors under radiation\nexposure. In this letter, the threshold voltage shift of the floating gate\ntransistor (FGT) is analyzed by a mathematical model.",
        "positive": "Evaluation of bulk-interface contributions to Edelstein\n  magnetoresistance at metal/oxide interfaces: We report a systematic study on Edelstein magnetoresistance (Edelstein MR) in\nCo25Fe75/Cu/Bi2O3 heterostructures with a strong spin-orbit interaction at the\nCu/Bi2O3 interface. We succeed in observing a significant dependence of the\nEdelstein MR on both Cu layer thickness and temperature, and also develop a\ngeneral analytical model considering distinct bulk and interface contributions\non spin relaxation. Our analysis, based on the above model, quantitatively\nillustrates a unique property of the spin transport near the Rashba interface,\nrevealing a prominent role of the spin relaxation process by determining the\nratios of the spin relaxation inside and outside the interface. We further find\nthe characteristic spin transport is unaffected by temperature. Our results\nprovide an essential tool for exploring the transport in a system with\nspin-momentum-locked two-dimensional states."
    },
    {
        "anchor": "Interaction between stimulated current injection and polariton\n  condensate: In this paper, we see a strong effect of the injected current on the light\nemission from the polariton condensate in an n-i-n structure, when we monitor\nthe luminescence intensity under applied bias at various pump powers. We\npresent here three thresholds for nonlinear increase of the intensity. We show\nthat small changes of the incoherent injected current lead to stimulated\nenhancement of the coherent light emission from free carriers. We conclude that\nthe polariton condensate-current system is a highly nonlinear electro-optical\nsystem.",
        "positive": "Precise Wigner-Weyl calculus for the honeycomb lattice: In this paper we propose the precise Wigner-Weyl calculus for the lattice\nmodels defined on the honeycomb lattice. We construct two symbols of operators:\nthe $\\mathscr{B}$-symbol, which is similar to the symbol introduced by F. Buot,\nand the $W$ (or, Weyl) symbol. The latter possesses the set of useful\nproperties. These identities allow us to use it in physical applications. In\nparticular, we derive topological expression for the Hall conductivity through\nthe Wigner transformed Green function. This expression may be used for the\ndescription of quantum Hall effect in the systems with artificial honeycomb\nlattice, when magnetic flux through the lattice cell is of the order of\nelementary quantum of magnetic flux."
    },
    {
        "anchor": "Long-lived memory for mesoscopic quantum bits: We describe a technique to create long-lived quantum memory for quantum bits\nin mesoscopic systems. Specifically we show that electronic spin coherence can\nbe reversibly mapped onto the collective state of the surrounding nuclei. The\ncoherent transfer can be efficient and fast and it can be used, when combined\nwith standard resonance techniques, to reversibly store coherent superpositions\non the time scale of seconds. This method can also allow for ``engineering''\nentangled states of nuclear ensembles and efficiently manipulating the stored\nstates. We investigate the feasibility of this method through a detailed\nanalysis of the coherence properties of the system.",
        "positive": "Two-qubit sweet spots for capacitively coupled exchange-only spin qubits: The implementation of high fidelity two-qubit gates is a bottleneck in the\nprogress towards universal quantum computation in semiconductor quantum dot\nqubits. We study capacitive coupling between two triple quantum dot spin qubits\nencoded in the $S = 1/2$, $S_z = -1/2$ decoherence-free subspace -- the\nexchange-only (EO) spin qubits. We report exact gate sequences for CPHASE and\nCNOT gates, and demonstrate theoretically, the existence of multiple two-qubit\nsweet spots (2QSS) in the parameter space of capacitively coupled EO qubits.\nGate operations have the advantage of being all-electrical, but charge noise\nthat couple to electrical parameters of the qubits cause decoherence. Assuming\nnoise with a 1/f spectrum, two-qubit gate fidelities and times are calculated,\nwhich provide useful information on the noise threshold necessary for\nfault-tolerance. We study two-qubit gates at single and multiple parameter\n2QSS. In particular, for two existing EO implementations -- the resonant\nexchange (RX) and the always-on exchange-only (AEON) qubits -- we compare\ntwo-qubit gate fidelities and times at positions in parameter space where the\n2QSS are simultaneously single-qubit sweet spots (1QSS) for the RX and AEON.\nThese results provide a potential route to the realization of high fidelity\nquantum computation."
    },
    {
        "anchor": "Spin-based quantum computation in multielectron quantum dots: In a quantum computer the hardware and software are intrinsically connected\nbecause the quantum Hamiltonian (or more precisely its time development) is the\ncode that runs the computer. We demonstrate this subtle and crucial\nrelationship by considering the example of electron-spin-based solid state\nquantum computer in semiconductor quantum dots. We show that multielectron\nquantum dots with one valence electron in the outermost shell do not behave\nsimply as an effective single spin system unless special conditions are\nsatisfied. Our work compellingly demonstrates that a delicate synergy between\ntheory and experiment (between software and hardware) is essential for\nconstructing a quantum computer.",
        "positive": "Topological Band Systems and Finite Size Effects: The recent discoveries about topological insulators have been promoting\ntheoretical and experimental research. In this dissertation, the basic concepts\nof topological insulators and the Quantum Hall Effect are reviewed focusing the\ndiscussion on edge states and their band structure. Lattice models with pierced\nmagnetism are described and the Hofstadter model is presented for bounded\nsystems with and without an in-site disorder. An overview of the experimental\nprocedure based on cold atoms in optical lattices with synthetic dimensions is\ngiven. In order to understand to what extent these small systems of cold atoms\nmimic the behaviour of a topological insulator, an analysis of some finite size\neffects is provided and a deduction of the gap opening in the band structure is\npresented using perturbation theory."
    },
    {
        "anchor": "Water Transport through Carbon Nanotubes with the Radial Breathing Mode: Molecular dynamics simulations are performed to investigate the water\npermeation across the single-walled carbon nanotube (SWCNT) with the radial\nbreathing mode (RBM) vibration. It is found that the RBM can play a significant\nrole in breaking hydrogen bonds of the water chain, accordingly increasing the\nnet flux dramatically, and reducing drastically the average number of water\nmolecules inside the tube with the frequency ranging from 5000 to 11000 GHz,\nwhile far away from this frequency region the transport properties of water\nmolecules are almost unaffected by the RBM. This phenomenon can be understood\nas the resonant response of the water molecule chain to the RBM. Our findings\nare expected to be helpful for the design of high-flux nanochannels and the\nunderstanding of biological activities especially the water channelling.",
        "positive": "Demonstrating Entanglement by Testing Bell's Theorem in Majorana Wires: We propose an experiment that would establish the entanglement of Majorana\nzero modes in semiconductor nanowires by testing the Bell and\nClauser-Horne-Shimony-Holt inequalities. Our proposal is viable with realistic\nsystem parameters, simple \"keyboard\" gating, and projective measurement.\nSimulation results indicate entanglement can be demonstrated with moderately\naccurate gate operations. In addition to providing further evidence for the\nexistence of the Majorana bound states, our proposal could be used as an\nexperimental stepping stone to more complicated braiding experiments."
    },
    {
        "anchor": "Suppression of superfluidity by dissipation -- An application to failed\n  superconductor: The ground states of bosons have been classified into superfluid, Mott\ninsulator, and bose glass. Recent experiments in two-dimensional\nsuperconductors strongly suggest the existence of the fourth quantum state of\nCooper pairs, i.e., bose metal or quantum metal, where the resistivity remains\nconstant at lowest temperature. However, its theoretical understanding remains\nunsettled. In this paper, we show theoretically that the bosons in the dilute\nlimit subject to dissipation can lose the superfluidity and remain metallic,\nutilizing the Feynman's picture of superfluidity in the first quantized\nformulation. This result is relevant to the quantum vortices under an external\nmagnetic field in two-dimensional superconductors with the finite resistivity\nof the normal core as the source of dissipation.",
        "positive": "Broadband parametric amplification for multiplexed SiMOS quantum dot\n  signals: Spins in semiconductor quantum dots hold great promise as building blocks of\nquantum processors. Trapping them in SiMOS transistor-like devices eases future\nindustrial scale fabrication. Among the potentially scalable readout solutions,\ngate-based dispersive radiofrequency reflectometry only requires the already\nexisting transistor gates to readout a quantum dot state, relieving the need\nfor additional elements. In this effort towards scalability, traveling-wave\nsuperconducting parametric amplifiers significantly enhance the readout\nsignal-to-noise ratio (SNR) by reducing the noise below typical cryogenic\nlow-noise amplifiers, while offering a broad amplification band, essential to\nmultiplex the readout of multiple resonators. In this work, we demonstrate a\n3GHz gate-based reflectometry readout of electron charge states trapped in\nquantum dots formed in SiMOS multi-gate devices, with SNR enhanced thanks to a\nJosephson traveling-wave parametric amplifier (JTWPA). The broad, tunable 2GHz\namplification bandwidth combined with more than 10dB ON/OFF SNR improvement of\nthe JTWPA enables frequency and time division multiplexed readout of interdot\ntransitions, and noise performance near the quantum limit. In addition, owing\nto a design without superconducting loops and with a metallic ground plane, the\nJTWPA is flux insensitive and shows stable performances up to a magnetic field\nof 1.2T at the quantum dot device, compatible with standard SiMOS spin qubit\nexperiments."
    },
    {
        "anchor": "Suppression of Spin Pumping Between Ni$_{80}$Fe$_{20}$ and Cu by a\n  Graphene Interlayer: We compare ferromagnetic resonance measurements of Permalloy\nNi$_{80}$Fe$_{20}$ (Py) films sputtered onto Cu(111) films with and without a\ngraphene (Gr) interlayer grown by chemical vapor deposition before Py\ndeposition. A two-angle sputtering method ensured that neither Gr nor Py was\ndegraded by the sample preparation process. We find the expected damping\nenhancement from spin pumping for the Py/Cu case and no detectable enhancement\nfor the Py/Gr/Cu case. Since damping is sensitive to effects other than spin\npumping, we used magnetometry to verify that differences in Py magnetostatic\nproperties are not responsible for the difference in damping. We attribute the\nsuppression of spin pumping in Py/Gr/Cu to the large contact resistance of the\nGr/Cu interface.",
        "positive": "Spin-transport in multi-terminal normal metal - ferromagnet systems with\n  non-collinear magnetizations: A theory of spin-transport in hybrid normal metal - ferromagnetic electronic\ncircuits is developed, taking into account non-collinear spin-accumulation.\nSpin-transport through resistive elements is described by 4 conductance\nparameters. Microscopic expression for these conductances are derived in terms\nof scattering matrices and explicitly calculated for simple models. The circuit\ntheory is applied to 2-terminal and 3-terminal devices attached to\nferromagnetic reservoirs."
    },
    {
        "anchor": "General Green's function formalism for transport calculations with\n  spd-Hamiltonians and giant magnetoresistance in Co and Ni based magnetic\n  multilayers: A novel, general Green's function technique for elastic spin-dependent\ntransport calculations is presented, which (i) scales linearly with system size\nand (ii) allows straightforward application to general tight-binding\nHamiltonians (spd in the present work). The method is applied to studies of\nconductance and giant magnetoresistance (GMR) of magnetic multilayers in CPP\n(current perpendicular to planes) geometry in the limit of large coherence\nlength. The magnetic materials considered are Co and Ni, with various\nnon-magnetic materials from the 3d, 4d, and 5d transition metal series.\nRealistic tight-binding models for them have been constructed with the use of\ndensity functional calculations. We have identified three qualitatively\ndifferent cases which depend on whether or not the bands (densities of states)\nof a non-magnetic metal (i) form an almost perfect match with one of spin\nsub-bands of the magnetic metal (as in Cu/Co spin valves); (ii) have almost\npure sp character at the Fermi level (e.g. Ag); (iii) have almost pure d\ncharacter at the Fermi energy (e.g. Pd, Pt). The key parameters which give rise\nto a large GMR ratio turn out to be (i) a strong spin polarization of the\nmagnetic metal, (ii) a large energy offset between the conduction band of the\nnon-magnetic metal and one of spin sub-bands of the magnetic metal, and (iii)\nstrong interband scattering in one of spin sub-bands of a magnetic metal. The\npresent results show that GMR oscillates with variation of the thickness of\neither non-magnetic or magnetic layers, as observed experimentally.",
        "positive": "Spin-Wave Spectrum in Magnetic Nanodot with Continuous Transition\n  between Vortex, Bloch-type Skyrmion and N\u00e9el-type Skyrmion States: We study spin-wave excitations in a circular ferromagnetic nanodot in\ndifferent inhomogeneous, topologically non-trivial magnetization states,\nspecifically, vortex and skyrmion states. Gradual change in the strength of the\nout-of-plane magnetic anisotropy and the Dzyaloshinskii-Moriya exchange\ninteraction leads to continuous phase transitions between different stable\nmagnetic configurations and allows for mapping of dynamic spin modes in and\nbetween the vortex, Bloch-type skyrmion and N\\'eel-type skyrmion states. Our\nstudy elucidates the connections between gyrotropic modes, azimuthal spin waves\nand breathing modes in various stable magnetization states and helps to\nunderstand the rich spin excitation spectrum on the skyrmion background."
    },
    {
        "anchor": "Current Correlations from a Mesoscopic Anyon Collider: Fermions and bosons are fundamental realizations of exchange statistics,\nwhich governs the probability for two particles being close to each other\nspatially. Anyons in the fractional quantum Hall effect are an example for\nexchange statistics intermediate between bosons and fermions. We analyze a\nmesoscopic setup in which two dilute beams of anyons collide with each other,\nand relate the correlations of current fluctuations to the probability of\nparticles excluding each other spatially. While current correlations for\nfermions vanish, negative correlations for anyons are a clear signature of a\nreduced spatial exclusion as compared to fermions.",
        "positive": "On quantum Hall effect: Covariant derivatives, Wilson lines, gauge\n  potentials, lattice Weyl transforms, and Chern numbers: We show that the gauge symmetry of the nonequilibrium quantum transport of\nChern insulator in a uniform electric field is governed by the Wilson line of\nparallel transport operator coupled with the dynamical translation operator.\nThis is dictated by the minimal coupling of derivatives with gauge fields in U\n(1) gauge theory. This parallel transport symmetry consideration leads to the\ninteger quantum Hall effect in electrical conductivity obtained to first-order\ngradient expansion of the nonequilibrium quantum transport equations."
    },
    {
        "anchor": "An ab-initio approach to describe coherent and non-coherent exciton\n  dynamics: The use of ultra-short laser pulses to pump and probe materials activates a\nwealth of processes which involve the coherent and non coherent dynamics of\ninteracting electrons out of equilibrium. Non equilibrium (NEQ) many body\nperturbation theory (MBPT) offers an equation of motion for the density-matrix\nof the system which well describes both coherent and non coherent processes. In\nthe non correlated case there is a clear relation between these two regimes and\nthe matrix elements of the density-matrix. The same is not true for the\ncorrelated case, where the potential binding of electrons and holes in\nexcitonic states need to be considered. In the present work we discuss how\nNEQ-MBPT can be used to describe the dynamics of both coherent and non-coherent\nexcitons in the low density regime. The approach presented is well suited for\nan ab initio implementation.",
        "positive": "Inside the perpendicular spin-torque memristor: Memristors are non-volatile nano-resistors. Their resistance can be tuned by\napplied currents or voltages and set to a large number of levels between two\nlimit values. Thanks to these properties, memristors are ideal building blocks\nfor a number of applications such as multilevel non-volatile memories and\nartificial nano-synapses, which are the focus of this work. A key point towards\nthe development of large scale memristive neuromorphic hardware is to build\nthese neural networks with a memristor technology compatible with the best\ncandidates for the future mainstream non-volatile memories. Here we show the\nfirst experimental achievement of a memristor compatible with Spin-Torque\nMagnetic Random Access Memory. The resistive switching in our spin-torque\nmemristor is linked to the displacement of a magnetic domain wall by\nspin-torques in a perpendicularly magnetized magnetic tunnel junction. We\ndemonstrate that our magnetic synapse has a large number of intermediate\nresistance states, sufficient for neural computation. Moreover, we show that\nengineering the device geometry allows leveraging the most efficient spin\ntorque to displace the magnetic domain wall at low current densities and thus\nto minimize the energy cost of our memristor. Our results pave the way for\nspin-torque based analog magnetic neural computation."
    },
    {
        "anchor": "Role of atomic spin-mechanical coupling in the problem of magnetic\n  biocompass: It is a well established notion that animals can detect the Earth's magnetic\nfield, while the biophysical origin of such magnetoreception is still elusive.\nRecently, a magnetic receptor Drosophila CG8198 (MagR) with a rod-like protein\ncomplex is reported [Qin \\emph{et al}., Nat. Mater. \\textbf{15}, 217 (2016)] to\nact like a compass needle to guide the magnetic orientation of animals. This\nview, however, is challenged [Meister, Elife \\textbf{5}, e17210 (2016)] by\narguing that thermal fluctuations beat the Zeeman coupling of the proteins's\nmagnetic moment with the rather weak geomagnetic field ($\\sim25-65$ $\\mu$T). In\nthis work, we show that the spin-mechanical interaction at the atomic scale\ngives rise to a high blocking temperature which allows a good alignment of\nprotein's magnetic moment with the Earth's magnetic field at room temperature.\nOur results provide a promising route to resolve the debate on the thermal\nbehaviors of MagR, and may stimulate a broad interest on spin-mechanical\ncouplings down to atomistic levels.",
        "positive": "Interacting quantum walkers: Two-body bosonic and fermionic bound states: We investigate the dynamics of bound states of two interacting particles,\neither bosons or fermions, performing a continuous-time quantum walk on a\none-dimensional lattice. We consider the situation where the distance between\nboth particles has a hard bound, and the richer situation where the particles\nare bound by a smooth confining potential. The main emphasis is on the velocity\ncharacterizing the ballistic spreading of these bound states, and on the\nstructure of the asymptotic distribution profile of their center-of-mass\ncoordinate. The latter profile generically exhibits many internal fronts."
    },
    {
        "anchor": "Measurement and control of electron wave packets from a single-electron\n  source: We report an experimental technique to measure and manipulate the\narrival-time and energy distributions of electrons emitted from a semiconductor\nelectron pump, operated as both a single-electron source and a two-electron\nsource. Using an energy-selective detector whose transmission we control on\npicosecond timescales, we can measure directly the electron arrival-time\ndistribution and we determine the upper-bound to the distribution width to be\n30 ps. We study the effects of modifying the shape of the voltage waveform that\ndrives the electron pump, and show that our results can be explained by a\ntunneling model of the emission mechanism. This information was in turn used to\ncontrol the emission-time difference and energy gap between a pair of\nelectrons.",
        "positive": "Self-rotation and synchronization in exciton-polariton condensates: Self-rotation occurs in an exciton-polariton condensate in a two-dimensional\nsemiconductor microcavity pumped by a nonresonant Gaussian laser beam. A wave\npacket of the condensate spontaneously rotates around the center of the pumped\nregion at a constant frequency breaking the rotation symmetry of the system.\nWhen two self-rotating condensates are created with an appropriate distance,\nsynchronization occurs between the dynamics of the self-rotating condensates."
    },
    {
        "anchor": "Kondo Regime of a Quantum Dot Molecule: A Finite-U Slave-Boson Approach: We study the electronic transport in a double quantum dot structure connected\nto leads in the Kondo regime for both series and parallel arrangements. By\napplying a finite-U slave boson technique in the mean field approximation we\nexplore the effect of level degeneracy in the conductance through the system.\nOur results show that for the series connection, as the energy difference of\nthe localized dot levels increases, the tunneling via the Kondo state is\ndestroyed. For the parallel configuration, we find an interesting interplay of\nstate symmetry and conductance. Our results are in good agrement with those\nobtained with other methods, and provide additional insights into the physics\nof the Kondo state in the double dot system.",
        "positive": "Intervalley Polaron in Atomically Thin Transition Metal Dichalcogenides: We study theoretically intervalley coupling in transition-metal\ndichalcogenide monolayers due to electron interaction with short-wavelength\nphonons. We demonstrate that this intervalley polaron coupling results in (i) a\nrenormalization of the conduction band spin splitting and (ii) an increase of\nthe electron effective masses. We also calculate the renormalization of the\ncyclotron energy and the Landau level splitting in the presence of an external\nmagnetic field. An inter-valley magneto-phonon resonance is uncovered. Similar,\nbut much weaker effects are also expected for the valence band holes. These\nresults might help to resolve the discrepancy between ab initio values of the\nelectron effective masses and the ones deduced from magneto-transport\nmeasurements."
    },
    {
        "anchor": "Topological effects and particle-physics analogies beyond the massless\n  Dirac-Weyl fermion in graphene nanorings: Armchair and zigzag edge terminations in planar hexagonal and trigonal\ngraphene nanorings are shown to underlie one-dimensional topological states\nassociated with distinctive energy gaps and patterns (e.g., linear dispersion\nof the energy of an hexagonal ring with an armchair termination versus\nparabolic dispersion for a zigzag terminated one) in the bands of the\ntight-binding spectra as a function of the magnetic field. A relativistic\nDirac-Kronig-Penney model analysis of the tight-binding Aharonov-Bohm behavior\nreveals that the graphene quasiparticle in an armchair hexagonal ring is a\ncondensed-matter realization of an ultrarelativistic fermion with a\nposition-dependent mass term, akin to the zero-energy fermionic solitons with\nfractional charge familiar from quantum field theory and from the theory of\npolyacetylene. The topological origins of the above behavior are highlighted by\ncontrasting it with the case of a trigonal armchair ring, where we find that\nthe quasiparticle excitations behave as familiar Dirac fermions with a constant\nmass. Furthermore, the spectra of a zigzag hexagonal ring correspond to the\nlow-kinetic-energy nonrelativistic regime of a leptonlike massive fermion. A\nonedimensional relativistic Lagrangian formalism coupling a fermionic and a\nscalar bosonic field via a Yukawa interaction, in conjunction with the breaking\nof the Z2 reflectional symmetry of the scalar field, is shown to unify the\nabove dissimilar behaviors.",
        "positive": "Transport of atoms in a quantum conveyor belt: We have performed experiments using a 3D-Bose-Einstein condensate of sodium\natoms in a 1D optical lattice to explore some unusual properties of\nband-structure. In particular, we investigate the loading of a condensate into\na moving lattice and find non-intuitive behavior. We also revisit the behavior\nof atoms, prepared in a single quasimomentum state, in an accelerating lattice.\nWe generalize this study to a cloud whose atoms have a large quasimomentum\nspread, and show that the cloud behaves differently from atoms in a single\nBloch state. Finally, we compare our findings with recent experiments performed\nwith fermions in an optical lattice."
    },
    {
        "anchor": "DC four point resistance of a double barrier quantum pump: We investigate the behavior of the dc voltage drop in a periodically driven\ndouble barrier structure (DBS) sensed by voltages probes that are weakly\ncoupled to the system. We find that the four terminal resistance $R_{4t}$\nmeasured with the probes located outside the DBS results identical to the\nresistance measured in the same structure under a stationary bias voltage\ndifference between left and right reservoirs. This result, valid beyond the\nadiabatic pumping regime, can be taken as an indication of the universal\ncharacter of $R_{4t}$ as a measure of the resistive properties of a sample,\nirrespectively of the mechanism used to induce the transport.",
        "positive": "Evidence for non-linear quasiparticle tunneling between fractional\n  quantum Hall edges: Remarkable nonlinearities in the differential tunneling conductance between\nfractional quantum Hall edge states at a constriction are observed in the\nweak-backscattering regime. In the $\\nu $ = 1/3 state a peak develops as\ntemperature is increased and its width is determined by the fractional charge.\nIn the range $2/3 \\le \\nu \\le 1/3$ this width displays a symmetric behavior\naround $\\nu $ = 1/2. We discuss the consistency of these results with available\ntheoretical predictions for inter-edge quasiparticle tunneling in the\nweak-backscattering regime."
    },
    {
        "anchor": "Sublattice asymmetry and spin-orbit interaction induced out-of-plane\n  spin polarization of photoelectrons: We study theoretically the effect of spin-orbit coupling and sublattice\nasymmetry in graphene on the spin polarization of photoelectrons. We show that\nsublattice asymmetry in graphene not only opens a gap in the band structure but\nin case of finite spin-orbit interaction it also gives rise to an out-of-plane\nspin polarization of electrons close to the Dirac point of the Brillouin zone.\nThis can be detected by measuring the spin polarization of photoelectrons and\ntherefore spin resolved photoemission spectroscopy can reveal the presence of a\nband gap even if it is too small to be observed directly by angle resolved\nphotoemission spectroscopy because of the finite resolution of measurements or\nbecause the sample is $p$-doped. We present analytical and numerical\ncalculations on the energy and linewidth dependence of photoelectron intensity\ndistribution and spin polarization.",
        "positive": "Comparison between Atomic Force Microscopy and Force Feedback Microscopy\n  static force curves: Atomic Force Microscopy (AFM) conventional static force curves and Force\nFeedback Microscopy (FFM) force curves acquired with the same cantilever at the\nsolid/air and solid/liquid interfaces are here compared. The capability of the\nFFM to avoid the jump to contact leads to the complete and direct measurement\nof the interaction force curve, including the attractive short-range van der\nWaals and chemical contributions. Attractive force gradients five times higher\nthan the lever stiffness do not affect the stability of the FFM static feedback\nloop. The feedback loop keeps the total force acting on the AFM tip equal to\nzero, allowing the use of soft cantilevers as force transducers to increase the\ninstrumental sensitivity. The attractive interactions due to the nucleation of\na capillary bridge at the native oxide silicon/air interface or due to a DLVO\ninteraction at the mica/deionized water interface have been measured. This set\nup, suitable for measuring directly and quantitatively interfacial forces, can\nbe exported to a SFA (Surface Force Apparatus)."
    },
    {
        "anchor": "Transport inefficiency in branched-out mesoscopic networks: An analog of\n  the Braess paradox: We present evidence for a counter-intuitive behavior of semiconductor\nmesoscopic networks that is the analog of the Braess paradox encountered in\nclassical networks. A numerical simulation of quantum transport in a two-branch\nmesoscopic network reveals that adding a third branch can paradoxically induce\ntransport inefficiency that manifests itself in a sizable conductance drop of\nthe network. A scanning-probe experiment using a biased tip to modulate the\ntransmission of one branch in the network reveals the occurrence of this\nparadox by mapping the conductance variation as a function of the tip voltage\nand position.",
        "positive": "Time-dependent density-matrix functional theory for trion excitations:\n  application to monolayer MoS2: We study possible optically excited bound states in monolayer MoS2: excitons\nand trions. For this purpose we formulate and apply a generalized\ntime-dependent density-matrix functional approach for bound states of multiple\nexcitations. The approach was used in the cases of three different types of the\nexchange-correlation (XC) kernel: 1) two local kernels: a phenomenological\ncontact and the adiabatic local-density approximation (ALDA) (X and XC); 2)\ngradient-corrected X kernels: GEA, PW91 and PBE; and 3) two long-range (LR)\nkernels: a phenomenological (Coulomb) and Slater kernels. In the case of\nexciton, we find that LDA and its gradient-corrected kernels lead to too weak\nbinding energy comparing to the experimental data, while the LR kernels are\ncapable to reproduce the experimental results. Similarly, in the LR case (as\nwell as in the case of local kernel), one can obtain the experimental value of\nthe trion binding energy by taking into account the screening effects. Our\nresults suggest that similar to the excitons, the LR structure of the XC kernel\nis necessary to describe the trion bound states. Our calculations for the first\ntime confirm theoretically with time-dependent density-functional theory\napproach that in agreement with experimental data the exciton and trion binding\nenergies are of order of hundreds (excitons) and tenth (trions) meVs, which can\nbe used in different technological applications at the room temperature regime.\nThe approach can be straightforwardly extended on the case of bound states and\nnonequilibrium response of systems with larger number of bound electrons and\nholes, including biexcitons."
    },
    {
        "anchor": "Transfer matrix method for optics in graphene layers: A transfer matrix method is developed for optical calculations of\nnon-interacting graphene layers. Within the framework of this method, optical\nproperties such as reflection, transmission and absorption for single-, double-\nand multi-layer graphene are studied. We also apply the method to structures\nconsisting of periodically arranged graphene layers, revealing well-defined\nphotonic band structures and even photonic bandgaps. Finally, we discuss\ngraphene plasmons and introduce a simple way to tune the plasmon dispersion.",
        "positive": "On the multifaceted journey for the invention of epitaxial quantum dots: Epitaxial semiconductor quantum dots have been, in the last 40 years or so,\nat the center of the research effort of a large community. The focus being on\nsemiconductor physics and devices, in view of the broad applications and\npotential, e.g., for efficient temperature insensitive lasers at telecom\nwavelengths, or as artificial atoms for quantum information processing. Our\nmanuscript aims at addressing, with an historical perspective, the specifics of\n(III-V) epitaxial quantum dot early developments (largely for light emitting)\nand subsequent years. We will not only highlight the variety of epitaxial\nstructures and methods, but also, intentionally glancing a didactic approach,\ndiscuss aspects that are, in general, little acknowledged or debated in the\npresent literature. The analyses will also naturally bring us to examine some\nof current challenges, in a field which, despite sensational achievements, is,\nremarkably, still far from being mature in its developments and applications."
    },
    {
        "anchor": "Highly efficient spin current generation by the spin Hall effect in\n  Au$_{1-x}$Pt$_x$: We report very efficient spin current generation by the spin Hall effect in\nthe alloy Au0.25Pt0.75, which, as determined by two different direct spin-orbit\ntorque measurements, exhibits a giant internal spin Hall ratio of > 0.58\n(anti-damping spin-orbit torque efficiency of ~ 0.35 in bilayers with Co), a\nrelatively low resistivity of ~ 83 uOhm cm, an exceptionally large spin Hall\nconductivity of > 7.0x10^5 ohm^-1 m^-1, and a spin diffusion length of 1.7 nm.\nThis work establishes Au0.25Pt0.75 as a milestone spin current generator that\nprovides greater energy efficiency than that yet obtained with other heavy\nmetals or with the topological insulators Bi2Se3 and (Bi,Se)2Te3. Our findings\nshould advance spin-orbit torque-based fundamental research and benefit the\ndevelopment of new fast, efficient spin-orbit torque-driven magnetic memories,\nskyrmion and chiral domain wall devices, and microwave and terahertz emitters.",
        "positive": "Force-gradient sensitive Kelvin probe force microscopy by dissipative\n  electrostatic force modulation: We report a Kelvin probe force microscopy (KPFM) implementation using the\ndissipation signal of a frequency modulation atomic force microscopy that is\ncapable of detecting the gradient of electrostatic force rather than\nelectrostatic force. It features a simple implementation and faster scanning as\nit requires no low frequency modulation. We show that applying a coherent ac\nvoltage with two times the cantilever oscillation frequency induces the\ndissipation signal proportional to the electrostatic force gradient which\ndepends on the effective dc bias voltage including the contact potential\ndifference. We demonstrate the KPFM images of a MoS$_2$ flake taken with the\npresent method is in quantitative agreement with that taken with the frequency\nmodulated Kelvin probe force microscopy technique."
    },
    {
        "anchor": "Electronic entanglement via quantum Hall interferometry in analogy to an\n  optical method: We present an interferometric scheme producing orbital entanglement in a\nquantum Hall system upon electron-hole pair emission via tunneling. The\nproposed setup is an electronic version of the optical interferometer proposed\nby Cabello et al. [Phys. Rev. Lett. 102, 040401 (2009)], and is feasible with\npresent technology. It requires single-channel propagation and a single primary\nsource. We discuss the creation of entanglement and its detection by the\nviolation of a Bell inequality.",
        "positive": "Shape resonances and shell effects in thin-film multiband\n  superconductors: We study analytically the evolution of superconductivity in clean\nquasi-two-dimensional multiband supercon- ductors as the film thickness enters\nthe nanoscale region by mean-field and semiclassical techniques. Tunneling into\nthe substrate and finite lateral size effects, which are important in\nexperiments, are also considered in our model. As a result, it is possible to\ninvestigate the interplay between quantum coherence effects, such as shape\nresonances and shell effects, with the potential to enhance superconductivity,\nand the multiband structure and the coupling to the substrate that tend to\nsuppress it. The case of magnesium diboride, which is the conventional\nsuperconductor with the highest critical temperature, is discussed in detail.\nOnce the effect of the substrate is considered, we still observe quantum size\neffects such as the oscillation of the critical temperature with the thickness\nbut without a significant enhancement of superconductivity. In thin films with\na sufficiently longer superconducting coherence length, it is, however,\npossible to increase the critical temperature above the bulk limit by tuning\nthe film thickness or lateral size."
    },
    {
        "anchor": "Effect of free carriers and impurities on density of states and optical\n  spectra of two-dimensional magneto-excitons: Density of states (DOS) and absorption spectrum of weakly doped, narrow\nquantum wells in high magnetic fields are calculated by realistic exact\ndiagonalization. The systems containing an electron--hole pair with and without\nan additional, second electron are compared. In DOS, the exciton--electron\ninteraction is shown to fill the gaps between Landau levels and to yield\nadditional discrete peaks corresponding to bound trion states. In absorption,\ninteraction with the additional free electron causes no shift or\nrenormalization of main, excitonic peaks. However, it results in additional,\nweaker peaks associated with bound trions in the lowest or higher Landau\nlevels. The calculation is supplemented with experimental photoluminescence and\nphotoluminescence-excitation studies of two-dimensional holes and electrons in\nhigh magnetic fields.",
        "positive": "Electric Dipole Spin Resonance for Heavy Holes in Quantum Dots: We propose and analyze a new method for manipulation of a heavy hole spin in\na quantum dot. Due to spin-orbit coupling between states with different orbital\nmomenta and opposite spin orientations, an applied rf electric field induces\ntransitions between spin-up and spin-down states. This scheme can be used for\ndetection of heavy-hole spin resonance signals, for the control of the spin\ndynamics in two-dimensional systems, and for determining important parameters\nof heavy-holes such as the effective $g$-factor, mass, spin-orbit coupling\nconstants, spin relaxation and decoherence times."
    },
    {
        "anchor": "Spectral maximum in the terahertz photoconductance of a quantum point\n  contact: The disappearance of the giant terahertz photoconductance of a quantum point\ncontact under the increase in the photon energy, which was discovered\nexperimentally (Otteneder et al., Phys. Rev. Applied 10 (2018) 014015) and\nstudied by the numerical calculations of the photon-stimulated transport (O.A.\nTkachenko et al., JETP Lett. 108 (2018) 396), is explained by the momentum\nconservation upon absorption of photons by tunneling electrons and on the base\nof perturbation theory calculations.",
        "positive": "Cavity electromechanics with parametric mechanical driving: Microwave optomechanical circuits have been demonstrated in the past years to\nbe extremely powerfool tools for both, exploring fundamental physics of\nmacroscopic mechanical oscillators as well as being promising candidates for\nnovel on-chip quantum limited microwave devices. In most experiments so far,\nthe mechanical oscillator is either used as a passive device element and its\ndisplacement is detected using the superconducting cavity or manipulated by\nintracavity fields. Here, we explore the possibility to directly and\nparametrically manipulate the mechanical nanobeam resonator of a cavity\nelectromechanical system, which provides additional functionality to the\ntoolbox of microwave optomechanical devices. In addition to using the cavity as\nan interferometer to detect parametrically modulated mechanical displacement\nand squeezed thermomechanical motion, we demonstrate that parametric modulation\nof the nanobeam resonance frequency can realize a phase-sensitive parametric\namplifier for intracavity microwave photons. In contrast to many other\nmicrowave amplification schemes using electromechanical circuits, the presented\ntechnique allows for simultaneous cooling of the mechanical element, which\npotentially enables this type of optomechanical microwave amplifier to be\nquantum-limited."
    },
    {
        "anchor": "A new method to epitaxially grow long-range ordered self-assembled InAs\n  quantum dots on (110) GaAs: We report on a new approach for positioning of self-assembled InAs quantum\ndots on (110) GaAs with nanometer precision. By combining self-assembly of\nquantum dots with molecular beam epitaxy on in-situ cleaved surfaces\n(cleaved-edge overgrowth) we have successfully fabricated arrays of long-range\nordered InAs quantum dots. Both atomic force microscopy and\nmicro-photoluminescence measurements demonstrate the ability to control size,\nposition, and ordering of the quantum dots. Furthermore, single dot\nphotoluminescence investigations confirm the high optical quality of the\nquantum dots fabricated.",
        "positive": "Atomistic investigation of low-field mobility in graphene nanoribbons: We have investigated the main scattering mechanisms affecting mobility in\ngraphene nanoribbons using detailed atomistic simulations. We have considered\ncarrier scattering due to acoustic and optical phonons, edge roughness, single\ndefects, and ionized impurities, and we have defined a methodology based on\nsimulations of statistically meaningful ensembles of nanoribbon segments. Edge\ndisorder heavily affects mobility at room temperature in narrower nanoribbons,\nwhereas charged impurities and phonons are hardly the limiting factors. Results\nare favorably compared to the few experiments available in the literature."
    },
    {
        "anchor": "Origins of transverse voltages generated by applied thermal gradients\n  and applied electric fields in ferrimagnetic-insulator/heavy-metal bilayers: We compare thermal-gradient-driven transverse voltages in\nferrimagnetic-insulator/heavy-metal bilayers (Tm3Fe5O12/W and Tm3Fe5O12/Pt) to\ncorresponding electrically-driven transverse resistances at and above room\ntemperature. We find for Tm3Fe5O12/W that the thermal and electrical effects\ncan be explained by a common spin-current detection mechanism, the physics\nunderlying spin Hall magnetoresistance (SMR). However, for Tm3Fe5O12/Pt the\nratio of the electrically-driven transverse voltages (planar Hall\nsignal/anomalous Hall signal) is much larger than the ratio of corresponding\nthermal-gradient signals, a result which is very different from expectations\nfor a SMR-based mechanism alone. We ascribe this difference to a\nproximity-induced magnetic layer at the Tm3Fe5O12/Pt interface.",
        "positive": "Electronic transport through bilayer graphene flakes: We investigate the electronic transport properties of a bilayer graphene\nflake contacted by two monolayer nanoribbons. Such a finite-size bilayer flake\ncan be built by overlapping two semiinfinite ribbons or by depositing a\nmonolayer flake onto an infinite nanoribbon. These two structures have a\ncomplementary behavior, that we study and analyze by means of a tight-binding\nmethod and a continuum Dirac model. We have found that for certain energy\nranges and geometries, the conductance of these systems oscillates markedly\nbetween zero and the maximum value of the conductance, allowing for the design\nof electromechanical switches. Our understanding of the electronic transmission\nthrough bilayer flakes may provide a way to measure the interlayer hopping in\nbilayer graphene."
    },
    {
        "anchor": "The strong modulation limit of excitons and trions in moir\u00e9 materials: The optical properties of weakly-doped two-dimensional materials are\ndominated by strong exciton and trion absorption and luminescence features. In\nthis article we examine the influence of moir\\'e patterns in semiconductor\nheterobilayers on exciton and trion states in the limit of strong moir\\'e\nmodulation potentials, commenting on similarities and differences compared to\nthe case of excitons and trions in semiconductor quantum dots. We discuss\nstrategies for using optical properties as quantitative probes of moir\\'e\nmaterials, and the prospects for exploiting moir\\'e materials to design unique\nlight emitters.",
        "positive": "Huge field-effect surface charge injection and conductance modulation in\n  metallic thin films by electrochemical gating: The field-effect technique, popular thanks to its application in common\nfield-effect transistors, is here applied to metallic thin films by using as a\ndielectric a novel polymer electrolyte solution. The maximum injected surface\ncharge, determined by a suitable modification of a classic method of\nelectrochemistry called double-step chronocoulometry, reached some units in\n10^15 charges/cm^2. At room temperature, relative variations of resistance up\nto 8%, 1.9% and 1.6% were observed in the case of gold, silver and copper,\nrespectively and, if the films are thick enough (> 25 nm), results can be\nnicely explained within a free-electron model with parallel resistive channels.\nThe huge charge injections achieved make this particular field-effect technique\nvery promising for a vast variety of materials such as unconventional\nsuperconductors, graphene and 2D-like materials."
    },
    {
        "anchor": "Quantitatively analyzing the mechanism of giant circular dichroism in\n  extrinsic plasmonic chiral nanostructures by the interplay of electric and\n  magnetic dipoles: The plasmonic chirality has drawn a lot of attention because of the tunable\ncircular dichroism (CD) and the enhancement for the signal of chiral molecules.\nDifferent mechanisms have been proposed for explaining the plasmonic CD,\nhowever, a quantitative one like ab initio mechanism in chiral molecules is\nstill unavailable. In this work, a mechanism similar to the chiral molecules is\nanalyzed. The giant extrinsic circular dichroism of plasmonic splitting\nrectangle ring is quantitatively investigated theoretically. The interplay of\nelectric and magnetic modes of the meta-structure is proposed to explain the\ngiant CD. The interplay is analyzed both in an analytical coupled\nelectric-magnetic dipoles model and finite element method model. The surface\ncharge distributions show that the circular current yielded in the splitting\nrectangle ring makes it behave like a magneton at some resonant modes, which\ninteract with electric modes and results in a mixing of the two kinds of modes.\nThe strong interplay of the two kinds of modes is mainly responsible for the\ngiant CD.The analysis of the chiral near field of the structure shows potential\napplications in chiral molecule sensing.",
        "positive": "Optimal spin-entangled electron-hole pair pump: A nonperturbative theory is presented for the creation by an oscillating\npotential of spin-entangled electron-hole pairs in the Fermi sea. In the weak\npotential limit, considered earlier by Samuelsson and Buttiker, the\nentanglement production is much less than one bit per cycle. We demonstrate\nthat a strong potential oscillation can produce an average of one Bell pair per\ntwo cycles, making it an efficient source of entangled flying qubits."
    },
    {
        "anchor": "Circular dichroism of emergent chiral stacking orders in\n  quasi-one-dimensional charge density waves: Chirality-driven optical properties in charge density waves are of\nfundamental and practical importance. Here, we investigate the interaction\nbetween circularly polarized light and emergent chiral stacking orders in\nquasi-one-dimensional (quasi-1D) charge-density waves (CDW) with\ndensity-functional theory calculations. In our specific system, self-assembled\nIn nanowires on Si(111) surface, spontaneous mirror symmetry breaking leads to\nsymmetrically distinct four degenerate quasi-1D CDW structures, which exhibit\ngeometrical chirality. Such geometrical chirality may naturally induce\noptically active phenomena even when the quasi-1D CDW structures are stacked\nperpendicular to the CDW chain direction. Indeed, we find that left- and\nright-chiral stacking orders show distinct circular dichroism responses while a\nnonchiral stacking order does no circular dichroism. Such optical responses are\nattributed to the existence of glide mirror symmetry of the CDW stacking\norders. Our findings suggest that the CDW chiral stacking orders can lead to\ndiverse active optical phenomena such as chirality-dependent circular\ndichroism, which can be observed in scanning tunneling luminescence\nmeasurements with circularly polarized light.",
        "positive": "On thresholdless lasing features in high-$\u03b2$ nitride nanobeam\n  cavities: a quantum optical study: Exploring the limits of spontaneous emission coupling is not only one of the\ncentral goals in the development of nanolasers, it is also highly relevant\nregarding future large-scale photonic integration requiring energy-efficient\ncoherent light sources with a small footprint. These studies are accompanied by\na vivid debate on how to prove and interpret lasing in the high-$\\beta$ regime.\nWe investigate close-to-ideal spontaneous emission coupling in GaN nanobeam\nlasers grown on silicon. Due to their high optical quality, such nanobeam\ncavities allow for efficient funneling of spontaneous emission from the quantum\nwell gain material into the laser mode. By performing a comprehensive optical\nand quantum-optical characterization, supported by microscopic modeling of the\nnanolasers, we identify high-$\\beta$ lasing at room temperature and show a\nlasing transition in the absence of a threshold nonlinearity at 156 K. This\npeculiar characteristic is explained in terms of a temperature and excitation\npower dependent interplay between 0D and 2D gain contributions."
    },
    {
        "anchor": "In-plane magnetoelectric response in bilayer graphene: A graphene bilayer shows an unusual magnetoelectric response whose magnitude\nis controlled by the valley-isospin density, making it possible to link\nmagnetoelectric behavior to valleytronics. Complementary to previous studies,\nwe consider the effect of static homogeneous electric and magnetic fields that\nare oriented parallel to the bilayer's plane. Starting from a tight-binding\ndescription and using quasi-degenerate perturbation theory, the low-energy\nHamiltonian is derived including all relevant magnetoelectric terms whose\nprefactors are expressed in terms of tight-binding parameters. We confirm the\nexistence of an expected axion-type pseudoscalar term, which turns out to have\nthe same sign and about twice the magnitude of the previously obtained\nout-of-plane counterpart. Additionally, small anisotropic corrections to the\nmagnetoelectric tensor are found that are fundamentally related to the skew\ninterlayer hopping parameter $\\gamma_4$. We discuss possible ways to identify\nmagnetoelectric effects by distinctive features in the optical conductivity.",
        "positive": "Thermodynamic density of states of two-dimensional GaAs systems near the\n  apparent metal-insulator transition: We perform combined resistivity and compressibility studies of\ntwo-dimensional hole and electron systems which show the apparent\nmetal-insulator transition - a crossover in the sign of dR/dT with changing\ndensity. No thermodynamic anomalies have been detected in the crossover region.\nInstead, despite a ten-fold difference in r_s, the compressibility of both\nelectrons and holes is well described by the theory of nonlinear screening of\nthe random potential. We show that the resistivity exhibits a scaling behavior\nnear the percolation threshold found from analysis of the compressibility.\nNotably, the percolation transition occurs at a much lower density than the\ncrossover."
    },
    {
        "anchor": "Excitons in asymmetric quantum wells: Resonance dielectric response of excitons is studied for the high-quality\nGaAs/InGaAs heterostructures with wide asymmetric quantum wells (QWs). To\nhighlight effects of the QW asymmetry, we have grown and studied several\nheterostructures with nominally square QWs as well as with triangle-like QWs.\nSeveral quantum confined exciton states are experimentally observed as narrow\nexciton resonances with various profiles. A standard approach for the\nphenomenological analysis of the profiles is generalized by introducing of\ndifferent phase shifts for the light waves reflected from the QWs at different\nexciton resonances. Perfect agreement of the phenomenological fit to the\nexperimentally observed exciton spectra for high-quality structures allowed us\nto obtain reliable parameters of the exciton resonances including the exciton\ntransition energies, the radiative broadenings, and the phase shifts. A direct\nnumerical solution of Schr\\\"{o}dinger equation for the heavy-hole excitons in\nasymmetric QWs is used for microscopic modeling of the exciton resonances.\nRemarkable agreement with the experiment is achieved when the effect of indium\nsegregation during the heterostructure growth is taken into account. The\nsegregation results in a modification of the potential profile, in particular,\nin an asymmetry of the nominally square QWs.",
        "positive": "Phonon-Drag Thermopower at High Temperatures: The adiabatic cristal model is offered. It is shown that springy nuclei\noscillations relatively electronic envelops and waves of such oscillations\n(inherent oscillations and waves) may exist in crystals. The analysis of\nexperimental temperature dependencies of resistivity in semiconductors with\nelectron-vibrational centres has shown that inherent oscillations effectively\ninteract with crystalline phonons as well as with electrons and holes, creating\npowerful interaction of electrons and holes with phonons. The experimental\nnarrow peaks of phonon-drag thermoelectric power at Debye temperatures from 77K\nto 700K confirm existence of inherent oscillations waves in crystals. Inherent\noscillations and waves gives rise to strong electron-phonon interaction and\nprobably can bring about superconductivity at temperatures as below so and well\nabove room temperature."
    },
    {
        "anchor": "Josephson Effect in a Coulomb-blockaded SINIS Junction: The problem of Josephson current through Coulomb-blocked nanoscale\nsuperconductor-normal-superconductor structure with tunnel contacts is\nreconsidered. Two different contributions to the phase-biased supercurrent are\nidentified, which are dominant in the limits of weak and strong Coulomb\ninteraction. Full expression for the free energy valid at arbitrary Coulomb\nstrength is found. The current derived from this free energy interpolates\nbetween known results for weak and strong Coulomb interaction as phase bias\nchanges from 0 to pi. In the broad range of Coulomb strength the current-phase\nrelation is substantially non-sinusoidal and qualitatively different from the\ncase of semi-ballistic SNS junctions. Coulomb interaction leads to appearance\nof a local minimum in the current at some intermediate value of phase\ndifference applied to the junction.",
        "positive": "Noise and Counting Statistics of a Single Electron Emitter: Theory: We review the latest progress in understanding the fundamental noise\nproperties of a coherent single electron emitter known as the mesoscopic\ncapacitor. The system consists of a sub-micron cavity connected to a\ntwo-dimensional electron gas via a quantum point contact. When subject to\nperiodic gate voltage modulations, the mesoscopic capacitor absorbs and\nre-emits single electrons at giga-hertz frequencies as it has been demonstrated\nexperimentally. Recent high-frequency noise measurements have moreover allowed\nfor a precise characterization of the device in different operating regimes.\nHere we discuss a simple model of the basic charge transfer processes in the\nmesoscopic capacitor and show how the model is capable of fully reproducing the\nmeasured high-frequency noise spectrum. We extend our analysis to the counting\nstatistics of emitted electrons during a large number of periods which we use\nto discuss the accuracy of the mesoscopic capacitor as a single electron\nsource. Finally, we consider possible applications of the mesoscopic capacitor\nin future experiments and identify novel pathways for further theoretical\nresearch."
    },
    {
        "anchor": "Magnetoexcitons in transition-metal dichalcogenides monolayers,\n  bilayers, and van der Waals heterostructures: We study direct and indirect magnetoexcitons in Rydberg states in monolayers\nand heterostructures of transition-metal dichalcogenices (TMDCs) in an external\nmagnetic field, applied perpendicular to the monolayer or heterostructures. We\ncalculate binding energies of magnetoexcitons for the Rydberg states 1$s$,\n2$s$, 3$s$, and 4$s$ by numerical integration of the Schr\\\"{o}dinger equation\nusing the Rytova-Keldysh potential for direct magnetoexcitons and both the\nRytova-Keldysh and Coulomb potentials for indirect magnetoexcitons. Latter\nallows understanding the role of screening in TMDCs heterostructures. We report\nthe magnetic field energy contribution to the binding energies and diamagnetic\ncoefficients (DMCs) for direct and indirect magnetoexcitons. The tunability of\nthe energy contribution of direct and indirect magnetoexcitons by the magnetic\nfield is demonstrated. It is shown that binding energies and DMCs of indirect\nmagnetoexcitons can be manipulated by the number of hBN layers. Therefore, our\nstudy raises the possibility of controlling the binding energies of direct and\nindirect magnetostrictions in TMDC monolayers, bilayers and heterostructures\nusing magnetic field and opens an additional degree of freedom to tailor the\nbinding energies and DMCs for heterostructures by varying the number of hBN\nsheets between TMDC layers. The calculations of the binding energies and DMCs\nof indirect magnetoexcitons in TMDC heterostructures are novel and can be\ncompared with the experimental results when they will be available.",
        "positive": "Exciton-Plasmon Coupling Mediated Superior Photoresponse in 2D Hybrid\n  Phototransistors: The possibility of creating heterostructure of two-dimensional (2D) materials\nhas emerged as a viable route towards realizing novel optoelectronic devices.\nHowever, the low light absorption due to their small absorption cross section,\nlimits their realistic application. While light-matter interaction mediated by\nstrong exciton-plasmon coupling has been demonstrated to improve absorbance and\nspontaneous emission in a coupled TMDC and metallic nanostructures, the\nfabrication of tunable broadband phototransistor with high quantum yield is\nstill a challenging task. By synthesizing Ag nanoparticles (Ag NPs) capped with\na thin layer of polyvinylpyrrolidone (PVP) through chemical route, we report a\nlithography-free fabrication of a large area broadband superior gate-tunable\nhybrid phototransistor based on monolayer graphene decorated by WS$_2$-Ag NPs\nin a three-terminal device configuration. The fabricated device exhibits\nextremely high photoresponsivity (up to $3.2\\times 10^4$ A/W) which is more\nthan 5 times higher than the bare graphene/WS$_2$ hybrid device, along with a\nlow noise equivalent power (NEP) (~10$^{-13}$ W/Hz$^{0.5}$, considering 1/f\nnoise) and high specific detectivity ~1010 Jones in the wide (325-730 nm)\nwavelength region. The additional PVP capping of Ag NPs helps to suppress the\ndirect charge and heat transfer and most importantly, increases the device\nstability by preventing the degradation of WS$_2$-Ag hybrid system. The\nenhanced optical properties of the hybrid device are explained via dipole\nmediated strong exciton-plasmon coupling, corroborated by COMSOL Multiphysics\nsimulation. Our work demonstrates a strategy towards obtaining an\nenvironment-friendly, scalable, high-performance broadband phototransistor by\ntuning the exciton-plasmon coupling for new generation opto-electronic devices."
    },
    {
        "anchor": "Scanning tunneling microscope characterizations of a circular graphene\n  resonator realized with p-p junctions: Using low-temperature high-magnetic-field scanning tunneling microscopy and\nspectroscopy (STM/STS), we systematically study a graphene quantum dot (GQD)\ndefined by a circular graphene p-p junction. Inside the GQD, we observe a\nseries of quasi-bound states arising from whispering-gallery-mode (WGM)\nconfinement of the circular junction and directly visualize these quasi-bound\nstates down to atomic dimensions. By applying a strong magnetic field, a large\njump in energy of the quasi-bound states, which is about one-half the energy\nspacing between the quasi-bound states, is observed. Such a behavior results\nfrom turning on a {\\pi} Berry phase of massless Dirac fermions in graphene by a\nmagnetic field. Moreover, our experiment demonstrates that a quasi-bound state\nsplits into two peaks with an energy separation of about 26 meV when the Fermi\nlevel crosses the quasi-bound state, indicating that there are strong\nelectron-electron interactions in the GQD.",
        "positive": "Superconducting Quantum Interference Single-Electron Transistor: We propose the concept of a quantized single-electron source based on the\ninterplay between Coulomb blockade and magnetic flux-controllable\nsuperconducting proximity effect. We show that flux dependence of the induced\nenergy gap in the density of states of a nanosized metallic wire can be\nexploited as an efficient tunable energy barrier which enables charge pumping\nconfigurations with enhanced functionalities. This control parameter strongly\naffects the charging landscape of a normal metal island with non-negligible\nCoulombic energy. Under a suitable evolution of a time-dependent magnetic flux\nthe structure behaves likewise a turnstile for single electrons in a fully\nelectrostatic regime."
    },
    {
        "anchor": "Amplified and directional spontaneous emission from arbitrary composite\n  bodies: self-consistent treatment of Purcell effect below threshold: We study amplified spontaneous emission (ASE) from wavelength-scale composite\nbodies--complicated arrangements of active and passive media--demonstrating\nhighly directional and tunable radiation patterns, depending strongly on pump\nconditions, materials, and object shapes. For instance, we show that under\nlarge enough gain, $\\mathcal{PT}$ symmetric dielectric spheres radiate mostly\nalong either active or passive regions, depending on the gain distribution. Our\npredictions are based on a recently proposed fluctuating volume--current (FVC)\nformulation of electromagnetic radiation that can handle inhomogeneities in the\ndielectric and fluctuation statistics of active media, e.g. arising from the\npresence of non-uniform pump or material properties, which we exploit to\ndemonstrate an approach to modelling ASE in regimes where Purcell effect (PE)\nhas a significant impact on the gain, leading to spatial dispersion and/or\nchanges in power requirements. The nonlinear feedback of PE on the active\nmedium, captured by the Maxwell--Bloch equations but often ignored in linear\nformulations of ASE, is introduced into our linear framework by a\nself-consistent renormalization of the (dressed) gain parameters, requiring the\nsolution of a large system of nonlinear equations involving many linear\nscattering calculations.",
        "positive": "Two-Path Solid-State Interferometry Using Ultra-Subwavelength 2D\n  Plasmonic Waves: We report an on-chip solid-state Mach-Zehnder interferometer operating on\ntwo-dimensional (2D) plasmonic waves at microwave frequencies. Two plasmonic\npaths are defined with GaAs/AlGaAs 2D electron gas 80 nm below a metallic gate.\nThe gated 2D plasmonic waves achieve a velocity of ~c/300 (c: free-space light\nspeed). Due to this ultra-subwavelength confinement, the resolution of the 2D\nplasmonic interferometer is two orders of magnitude higher than that of its\nelectromagnetic counterpart at a given frequency. This GHz proof-of-concept at\ncryogenic temperatures can be scaled to the THz IR range for room temperature\noperation, while maintaining the benefits of the ultra-subwavelength\nconfinement."
    },
    {
        "anchor": "Observation of suppressed terahertz absorption in photoexcited graphene: When light is absorbed by a semiconductor, photoexcited charge carriers\nenhance the absorption of far-infrared radiation due to intraband transitions.\nWe observe the opposite behavior in monolayer graphene, a zero-gap\nsemiconductor with linear dispersion. By using time domain terahertz (THz)\nspectroscopy in conjunction with optical pump excitation, we observe a reduced\nabsorption of THz radiation in photoexcited graphene. The measured spectral\nshape of the differential optical conductivity exhibits non-Drude behavior. We\ndiscuss several possible mechanisms that contribute to the observed\nlow-frequency non-equilibrium optical response of graphene.",
        "positive": "Pumping in a mesoscopic ring with Ahronov-Casher effect: We investigate parametric pumping of spin and charge currents in a mesoscopic\nring interrupted by a tunnel barrier in presence of Aharonov-Casher (AC) effect\nand Aharonov-Bohm (AB) flux along the axis of the same ring. Generation of a dc\ncurrent is achieved by tuning the tunnel barrier strength and modulating in\ntime either a radial(transverse) electric field or the magnetic flux. A pure\nspin current is generated by the interplay of breaking spin reversal symmetry,\ndue to AC effect, and time-reversal symmetry breaking, intrinsic in parametric\npumping procedure. We analyze the conditions for operating the AB-AC ring as a\npure spin pump useful in spintronics and discuss generalization of our results\nto Rashba-gate-controlled rings."
    },
    {
        "anchor": "High-temperature excess current and quantum suppression of electronic\n  backscattering in a 1-D system: We consider the electronic current through a one-dimensional conductor in the\nballistic transport regime and show that the quantum oscillations of a weakly\npinned single scattering target results in a temperature- and bias-voltage\nindependent excess current at large bias voltages. This is a genuine effect on\ntransport that derives from an exponential reduction of electronic\nbackscattering in the elastic channel due to quantum delocalization of the\nscatterer and from suppression of low-energy electron backscattering in the\ninelastic channels caused by the Pauli exclusion principle. We show that both\nthe mass of the target and the frequency of its quantum vibrations can be\nmeasured by studying the differential conductance and the excess current. We\napply our analysis to the particular case of a weakly pinned C60 molecule\nencapsulated by a single-wall carbon nanotube and find that the discussed\nphenomena are experimentally observable.",
        "positive": "Time reversal symmetry broken fractional topological phases at zero\n  magnetic field: We extend the coupled-wire construction of quantum Hall phases, and search\nfor fractional topological insulating states in models of weakly coupled wires\nat zero external magnetic field. Focussing on systems beyond double copies of\nfractional quantum Hall states at opposite fields, we find that spin-spin\ninteractions can stabilize a large family of fractional topological phases with\nbroken time reversal invariance. The latter is manifest by spontaneous spin\npolarization, by a finite Hall conductivity, or by both. This suggests the\npossibility that fractional topological insulators may be unstable to\nspontaneous symmetry breaking."
    },
    {
        "anchor": "Imaging Spin Dynamics in Monolayer WS2 by Time-Resolved Kerr Rotation\n  Microscopy: Monolayer transition metal dichalcogenides (TMD) have immense potential for\nfuture spintronic and valleytronic applications due to their two-dimensional\nnature and long spin/valley lifetimes. We investigate the origin of these\nlong-lived states in n-type WS2 using time-resolved Kerr rotation microscopy\nand photoluminescence microscopy with ~1 micron spatial resolution. Comparing\nthe spatial dependence of the Kerr rotation signal and the photoluminescence\nreveals a correlation with neutral exciton emission, which is likely due to the\ntransfer of angular momentum to resident conduction electrons with long\nspin/valley lifetimes. In addition, we observe an unexpected anticorrelation\nbetween the Kerr rotation and trion emission, which provides evidence for the\npresence of long-lived spin/valley-polarized dark trions. We also find that the\nspin/valley polarization in WS2 is robust to magnetic fields up to 700 mT,\nindicative of spins and valleys that are stabilized with strong spin-orbit\nfields.",
        "positive": "Measurement of local optomechanical properties of a direct bandgap 2D\n  semiconductor: Strain engineering is a powerful tool for tuning physical properties of 2D\nmaterials, including monolayer transition metal dichalcogenides (TMD) -- direct\nbandgap semiconductors with strong excitonic response. Here, we demonstrate an\napproach for local characterization of strain-induced modification of excitonic\nphotoluminescence in TMD-based materials. We reversibly stress a monolayer of\nMoSe$_2$ with an AFM tip and perform spatio-spectral mapping of the excitonic\nphotoluminescence in the vicinity of the indentation point. To fully reproduce\nthe experimental data, we introduce the linear dependence of the exciton energy\nand corresponding photoluminescence intensity on the induced strain. Careful\naccount for the optical resolution allows extracting these quantities with good\nagreement with the previous measurements, which involved macroscopic sample\ndeformation. Our approach is a powerful tool for the study of local\noptomechanical properties of 2D direct bandgap semiconductors with strong\nexcitonic response."
    },
    {
        "anchor": "Semiconductor materials stacks for quantum dot spin qubits: In this perspective piece, I benchmark gallium arsenide, silicon, and\ngermanium as material platforms for gate-defined quantum dot spin qubits. I\nfocus on materials stacks, quantum dot architectures, bandstructure properties\nand qualifiers for disorder from electrical transport. This brief note is far\nfrom being exhaustive and should be considered a first introduction to the\nmaterials challenges and opportunities towards a larger spin qubit quantum\nprocessor.",
        "positive": "Triple Andreev dot chains in semiconductor nanowires: Kitaev chain is a theoretical model of a one-dimensional topological\nsuperconductor with Majorana zero modes at the two ends of the chain. With the\ngoal of emulating this model, we build a chain of three quantum dots in a\nsemiconductor nanowire. We observe Andreev bound states in each of the three\ndots and study their magnetic field and gate voltage dependence. Theory\nindicates that triple dot states acquire Majorana polarization when Andreev\nstates in all three dots reach zero energy in a narrow range of magnetic field.\nIn our device Andreev states in one of the dots reach zero energy at a lower\nfield than in other two, placing the Majorana regime out of reach. Devices with\ngreater uniformity or with independent control over\nsuperconductor-semiconductor coupling should can realize the Kitaev chain with\nhigh yield. Due to its overall tunability and design flexibility the quantum\ndot system remains promising for quantum simulation of interesting models and\nin particular for modular topological quantum devices."
    },
    {
        "anchor": "Quantum transport through a conducting bridge: Correlation between\n  surface disorder and bulk disorder: We explore a novel transport phenomenon by studying the effect of surface\ndisorder on electron transport through a finite size conductor with side\ncoupled metallic electrodes. In the strong disorder regime the current\namplitude increases with the increase of the surface disorder strength, while,\nthe amplitude decreases in the weak disorder regime. This behavior is\ncompletely opposite to that of bulk disordered system. In this article we also\ninvestigate the effects of the size of the conductor and the transverse\nmagnetic field on electron transport and see that the transport properties are\nsignificantly influenced by them.",
        "positive": "Determination of the complex microwave photoconductance of a single\n  quantum dot: A small quantum dot containing approximately 20 electrons is realized in a\ntwo-dimensional electron system of an AlGaAs/GaAs heterostructure. Conventional\ntransport and microwave spectroscopy reveal the dot's electronic structure. By\napplying a coherently coupled two-source technique, we are able to determine\nthe complex microwave induced tunnel current. The amplitude of this\nphotoconductance resolves photon-assisted tunneling (PAT) in the non-linear\nregime through the ground state and an excited state as well. The out-of-phase\ncomponent (susceptance) allows to study charge relaxation within the quantum\ndot on a time scale comparable to the microwave beat period."
    },
    {
        "anchor": "Magnetotunnelling in resonant tunnelling structures with spin-orbit\n  interaction: Magnetotunnelling spectroscopy of resonant tunnelling structures provides\ninformation on the nature of the two-dimensional electron gas in the well. We\ndescribe a model based on nonequilibrium Green's functions that allows for a\ncomprehensive study of the density of states, tunnelling currents and current\nspin polarization. The investigated effects include the electron-phonon\ninteraction, interface roughness scattering, Zeeman effect and the Rashba\nspin-orbit interaction. A qualitative agreement with experimental data is found\nregarding the satellite peaks. The spin polarization is predicted to be larger\nthan ten percent for magnetic fields above 2 Tesla and having a structure even\nat the satellite peaks. The Rashba effect is confirmed to be observable as a\nbeating pattern in the density of states but found to be too small to affect\nthe tunnelling current.",
        "positive": "Remote capacitive sensing in two-dimension quantum-dot arrays: We investigate gate-defined quantum dots in silicon on insulator nanowire\nfield-effect transistors fabricated using a foundry-compatible fully-depleted\nsilicon-on-insulator (FD-SOI) process. A series of split gates wrapped over the\nsilicon nanowire naturally produces a $2\\times n$ bilinear array of quantum\ndots along a single nanowire. We begin by studying the capacitive coupling of\nquantum dots within such a 2$\\times$2 array, and then show how such couplings\ncan be extended across two parallel silicon nanowires coupled together by\nshared, electrically isolated, 'floating' electrodes. With one quantum dot\noperating as a single-electron-box sensor, the floating gate serves to enhance\nthe charge sensitivity range, enabling it to detect charge state transitions in\na separate silicon nanowire. By comparing measurements from multiple devices we\nillustrate the impact of the floating gate by quantifying both the charge\nsensitivity decay as a function of dot-sensor separation and configuration\nwithin the dual-nanowire structure."
    },
    {
        "anchor": "Higher-order topological semimetal in acoustic crystals: The notion of higher-order topological insulators has endowed materials with\ntopological states beyond the first order. Particularly, a three-dimensional\n(3D) higher-order topological insulator can host topologically protected 1D\nhinge states, referred to as the second-order topological insulator, or 0D\ncorner states, referred to as the third-order topological insulator. Similarly,\na 3D higher-order topological semimetal can be envisaged if it hosts states on\nthe 1D hinges. Here we report the realization of a second-order topological\nWeyl semimetal in a 3D-printed acoustic crystal, which possesses Weyl points in\n3D momentum space, 2D Fermi arc states on surfaces and 1D gapless states on\nhinges. Like the arc surface states, the hinge states also connect the\nprojections of the Weyl points. Our experimental results evidence the existence\nof the higher-order topological semimetal, which may pave the way towards\ninnovative acoustic devices.",
        "positive": "Theoretical study of the role of the tip in enhancing the sensitivity of\n  differential conductance tunneling spectroscopy on magnetic surfaces: Based on a simple model for spin-polarized scanning tunneling spectroscopy\n(SP-STS) we study how tip magnetization and electronic structure affects the\ndifferential conductance (dI/dV) tunneling spectrum of an Fe(001) surface. We\ntake into account energy dependence of the vacuum decay of electron states, and\ntip electronic structure either using an ideal model or based on ab initio\nelectronic structure calculation. In the STS approach, topographic and magnetic\ncontributions to dI/dV can clearly be distinguished and analyzed separately.\nOur results suggest that the sensitivity of STS on a magnetic sample can be\ntuned and even enhanced by choosing the appropriate magnetic tip and bias\nsetpoint, and the effect is governed by the effective spin-polarization."
    },
    {
        "anchor": "Polarization Induced Switching Effect in Graphene Nanoribbon Edge-Defect\n  Junction: With nonequilibrium Green's function approach combined with density\nfunctional theory, we perform an ab initio calculation to investigate transport\nproperties of graphene nanoribbon junctions self-consistently. Tight-binding\napproximation is applied to model the zigzag graphene nanoribbon (ZGNR)\nelectrodes, and its validity is confirmed by comparison with GAUSSIAN03 PBC\ncalculation of the same system. The origin of abnormal jump points usually\nappearing in the transmission spectrum is explained with the detailed\ntight-binding ZGNR band structure. Transport property of an edge defect ZGNR\njunction is investigated, and the tunable tunneling current can be sensitively\ncontrolled by transverse electric fields.",
        "positive": "Quantum Phase Transition and Dynamically Enhanced Symmetry in Quadruple\n  Quantum Dot System: We propose a system of four quantum dots designed to study the competition\nbetween three types of interactions: Heisenberg, Kondo and Ising. We find a\nrich phase diagram containing two sharp features: a quantum phase transition\n(QPT) between charge-ordered and charge-liquid phases, and a dramatic resonance\nin the charge liquid visible in the conductance. The QPT is of the\nKosterlitz-Thouless type with a discontinuous jump in the conductance at the\ntransition. We connect the resonance phenomenon with the degeneracy of three\nlevels in the isolated quadruple dot and argue that this leads to a Kondo-like\ndynamical enhancement of symmetry from U(1) x Z_2 to U(1) x U(1)."
    },
    {
        "anchor": "Electronic and optical trends in carbon nanotubes under pure bending: The high aspect ratio of carbon nanotubes makes them prone to bending. To\nknow how bending affects the tubes is therefore crucial for tube identification\nand for electrical component design. Very few studies, however, have\ninvestigated tubes under small bending well below the buckling limit, because\nof technical problems due to broken translational symmetry. In this Letter a\ncost-effective and exact modeling of singe-walled nanotubes under such small\nbending is enabled by revised periodic boundary conditions, combined with\ndensity-functional tight-binding. The resulting, bending-induced changes in\nelectronic and optical properties fall in clear chirality-dependent trend\nfamilies. While the correct trends require full structural relaxation, they can\nbe understood by one general argument. To know these trends fills a fundamental\ngap in our understanding of the properties of carbon nanotubes.",
        "positive": "Strong Effects of Weak Localization in Charge Density Wave/Normal Metal\n  Hybrids: Collective transport through a multichannel disordered conductor in contact\nwith charge-density-wave electrodes is theoretically investigated. The\nstatistical distribution function of the threshold potential for charge-density\nwave sliding is calculated by random matrix theory. In the diffusive regime\nweak localization has a strong effect on the sliding motion."
    },
    {
        "anchor": "The Ferroelectric Point Contact: We formulate a scattering theory of polarization and heat transport through a\nballistic ferroelectric point contact. We predict a polarization current under\neither an electric field or a temperature difference that depends strongly on\nthe direction of the ferroelectric order and can be detected by its magnetic\nstray field and associated thermovoltage and Peltier effect.",
        "positive": "Hong-Ou-Mandel characterization of multiply charged Levitons: We review and develop recent results regarding Leviton excitations generated\nin topological states of matter - such as integer and fractional quantum Hall\nedge channels - and carrying a charge multiple of the electronic one. The\npeculiar features associated to these clean and robust emerging excitations can\nbe detected through current correlation measurements. In particular, relevant\ninformation can be extracted from the noise signal in generalized\nHong-Ou-Mandel experiments, where Levitons with different charges collide\nagainst each other at a quantum point contact. We describe this quantity both\nin the framework of the photo-assisted noise formalism and in terms of a very\ninteresting and transparent picture based on wave-packet overlap."
    },
    {
        "anchor": "Using thermal boundary conditions to engineer the quantum state of a\n  bulk magnet: The degree of contact between a system and the external environment can alter\ndramatically its proclivity to quantum mechanical modes of relaxation. We show\nthat controlling the thermal coupling of cubic centimeter-sized crystals of the\nIsing magnet $LiHo_xY_{1-x}F_4$ to a heat bath can be used to tune the system\nbetween a glassy state dominated by thermal excitations over energy barriers\nand a state with the hallmarks of a quantum spin liquid. Application of a\nmagnetic field transverse to the Ising axis introduces both random magnetic\nfields and quantum fluctuations, which can retard and speed the annealing\nprocess, respectively, thereby providing a mechanism for continuous tuning\nbetween the destination states. The non-linear response of the system\nexplicitly demonstrates quantum interference between internal and external\nrelaxation pathways.",
        "positive": "Diamagnetic persistent currents for electrons in ballistic billiards\n  subject to a point flux: We study the persistent current of noninteracting electrons subject to a\npointlike magnetic flux in the simply connected chaotic Robnik-Berry quantum\nbilliard, and also in an annular analog thereof. For the simply connected\nbilliard we find a large diamagnetic contribution to the persistent current at\nsmall flux, which is independent of the flux and is proportional to the number\nof electrons (or equivalently the density since we keep the area fixed). The\nsize of this diamagnetic contribution is much larger than mesoscopic\nfluctuations in the persistent current in the simply connected billiard, and\ncan ultimately be traced to the response of the angular momentum $l=0$ levels\n(neglected in semiclassical expansions) on the unit disk to a pointlike flux at\nits center. The same behavior is observed for the annular billiard when the\ninner radius is much smaller than the outer one, while the usual fluctuating\npersistent current and Anderson-like localization due to boundary scattering\nare seen when the annulus tends to a one-dimensional ring. We explore the\nconditions for the observability of this phenomenon."
    },
    {
        "anchor": "Spin Hall Current and Spin-transfer Torque in Ferromagnetic Metal: We theoretically examine the spin-transfer torque in the presence of\nspin-orbit interaction (SOI) at impurities in a ferromagnetic metal on the\nbasis of linear response theory. We obtained, in addition to the usual\nspin-transfer torque, a new contributioin $\\sim {\\bm j}_{\\rm\nSH}^{\\phantom{\\dagger}} \\cdot \\nabla {\\bm n}$ in the first order in SOI, where\n${\\bm j}_{\\rm SH}^{\\phantom{\\dagger}}$ is the spin Hall current driven by an\nexternal electric field. This is a reaction to inverse spin Hall effect driven\nby spin motive force in a ferromagnet.",
        "positive": "Helicity sensitive terahertz radiation detection by dual-grating-gate\n  high electron mobility transistors: We report on the observation of a radiation helicity sensitive photocurrent\nexcited by terahertz (THz) radiation in dual-grating-gate (DGG)\nInAlAs/InGaAs/InAlAs/InP high electron mobility transistors (HEMT). For a\ncircular polarization the current measured between source and drain contacts\nchanges its sign with the inversion of the radiation helicity. For elliptically\npolarized radiation the total current is described by superposition of the\nStokes parameters with different weights. Moreover, by variation of gate\nvoltages applied to individual gratings the photocurrent can be defined either\nby the Stokes parameter defining the radiation helicity or those for linear\npolarization. We show that artificial non-centrosymmetric microperiodic\nstructures with a two-dimensional electron system excited by THz radiation\nexhibit a dc photocurrent caused by the combined action of a spatially periodic\nin-plane potential and spatially modulated light. The results provide a proof\nof principle for the application of DGG HEMT for all-electric detection of the\nradiation's polarization state."
    },
    {
        "anchor": "Non-linear spin torque, pumping and cooling in\n  superconductor/ferromagnet systems: We study the effects of the coupling between magnetization dynamics and the\nelectronic degrees of freedom in a heterostructure of a metallic nanomagnet\nwith dynamic magnetization coupled with a superconductor containing a steady\nspin-splitting field. We predict how this system exhibits a non-linear spin\ntorque, which can be driven either with a temperature difference or a voltage\nacross the interface. We generalize this notion to arbitrary magnetization\nprecession by deriving a Keldysh action for the interface, describing the\ncoupled charge, heat and spin transport in the presence of a precessing\nmagnetization. We characterize the effect of superconductivity on the\nprecession damping and the anti-damping torques. We also predict the full\nnon-linear characteristic of the Onsager counterparts of the torque, showing up\nvia pumped charge and heat currents. For the latter, we predict a spin-pumping\ncooling effect, where the magnetization dynamics can cool either the nanomagnet\nor the superconductor.",
        "positive": "Theoretical studies of spin-dependent electrical transport through\n  carbon nanotbes: Spin-dependent coherent quantum transport through carbon nanotubes (CNT) is\nstudied theoretically within a tight-binding model and the Green's function\npartitioning technique. End-contacted metal/nanotube/metal systems are modelled\nand next studied in the magnetic context, i.e. either with ferromagnetic\nelectrodes or at external magnetic fields. The former case shows that quite a\nsubstantial giant magnetoresistance (GMR) effect occurs ($\\pm 20%$) for\ndisorder-free CNTs. Anderson-disorder averaged GMR, in turn, is positive and\nreduced down to several percent in the vicinity of the charge neutrality point.\nAt parallel magnetic fields, characteristic Aharonov-Bohm-type oscillations are\nrevealed with pronounced features due to a combined effect of:\nlength-to-perimeter ratio, unintentional electrode-induced doping, Zeeman\nsplitting, and energy-level broadening. In particular, a CNT is predicted to\nlose its ability to serve as a magneto-electrical switch when its length and\nperimeter become comparable. In case of perpendicular geometry, there are\nconductance oscillations approaching asymptotically the upper theoretical limit\nto the conductance, $4 e^2/h$. Moreover in the ballistic transport regime,\ninitially the conductance increases only slightly with the magnetic field or\nremains nearly constant because spin up- and spin down-contributions to the\ntotal magnetoresistance partially compensate each other."
    },
    {
        "anchor": "Ferromagnetism mediated by few electrons in a semimagnetic quantum dot: A (II,Mn)VI diluted magnetic semiconductor quantum dot with an integer number\nof electrons controlled with a gate voltage is considered. We show that a\nsingle conduction band electron is able to induce a spontaneous collective\nmagnetization of the Mn spins, overcoming the short range antiferromagnetic\ninteractions. The carrier mediated ferromagnetism in the dot survives at\ntemperatures above 1 Kelvin, two orders of magnitude larger than the Curie\ntemperature for the same material in bulk. The magnetic behavior of the dot\ndepends dramatically on the parity of the number of injected electrons.",
        "positive": "Ferromagnetism in graphene nanoribbons: split versus oxidative unzipped\n  ribbons: Two types of graphene nanoribbons: (a) potassium-split graphene nanoribbons\n(GNRs), and (b) oxidative unzipped and chemically converted graphene\nnanoribbons (CCGNRs) were investigated for their magnetic properties using the\ncombination of static magnetization and electron spin resonance measurements.\nThe two types of ribbons possess remarkably different magnetic properties.\nWhile the low temperature ferromagnet-like feature is observed in both types of\nribbons, such room temperature feature persists only in potassium-split\nribbons. The GNRs show negative exchange bias, but the CCGNRs exhibit a\n'positive exchange bias'. Electron spin resonance measurements infer that the\ncarbon related defects may responsible for the observed magnetic behaviour in\nboth types of ribbons. Furthermore, proton hyperfine coupling strength has been\nobtained from hyperfine sublevel correlation experiments performed on the GNRs.\nElectron spin resonance provides no indications for the presence of potassium\n(cluster) related signals, emphasizing the intrinsic magnetic nature of the\nribbons. Our combined experimental results may infer the coexistence of\nferromagnetic clusters with anti-ferromagnetic regions leading to disordered\nmagnetic phase. We discuss the origin of the observed contrast in the magnetic\nbehaviours of these two types of ribbons."
    },
    {
        "anchor": "Surface and volume plasmons in metallic nanospheres in semiclassical\n  RPA-type approach; near-field coupling of surface plasmons with semiconductor\n  substrate: The random-phase-approximation semiclassical scheme for description of\nplasmon excitations in large metallic nanospheres, with radius range 10-60 nm,\nis formulated in an all-analytical version. The spectrum of plasmons is\ndetermined including both surface and volume type excitations and their mutual\nconnections. The various channels for damping of surface plasmons are evaluated\nand the relevant resonance shifts are compared with the experimental data for\nmetallic nanoparticles of different size located in dielectric medium or on the\nsemiconductor substrate. The strong enhancement of energy transfer from the\nsurface plasmon oscillations to the substrate semiconductor is explained in the\nregime of a near-field coupling in agreement with recent experimental\nobservations for metallically nanomodified photo-diode systems.",
        "positive": "High Field magnetospectroscopy to probe the 1.4eV Ni color center in\n  diamond: A magneto-optical study of the 1.4 eV Ni color center in boron-free synthetic\ndiamond, grown at high pressure and high temperature, has been performed in\nmagnetic fields up to 56 T. The data is interpreted using the effective spin\nHamiltonian of Nazar\\'e, Nevers and Davies [Phys. Rev. B 43, 14196 (1991)] for\ninterstitial Ni$^{+}$ with the electronic configuration $3d^{9}$ and effective\nspin $S=1/2$. Our results unequivocally demonstrate the trigonal symmetry of\nthe defect which preferentially aligns along the [111] growth direction on the\n(111) face, but reveal the shortcomings of the crystal field model for this\nparticular defect."
    },
    {
        "anchor": "Spintronics: electron spin coherence, entanglement, and transport: Prospect of building spintronic devices in which electron spins store and\ntransport information has attracted strong attention in recent years. Here we\npresent some of our representative theoretical results on three fundamental\naspects of spintronics: spin coherence, spin entanglement, and spin transport.\nIn particular, we discuss our detailed quantitative theory for spin relaxation\nand coherence in electronic materials, resolving in the process a long-standing\npuzzle of why spin relaxation is extremely fast in Al (compared with other\nsimple metals). In the study of spin entanglement, we consider two electrons in\na coupled GaAs double-quantum-dot structure and explore the Hilbert space of\nthe double dot. The specific goal is to critically assess the quantitative\naspects of the proposed spin-based quantum dot quantum computer architecture.\nFurthermore, we discuss our theory of spin-polarized transport across a\nsemiconductor-metal interface. In particular, we study Andreev reflection,\nwhich enables us to quantify the degree of carrier spin polarization and the\nstrength of interfacial scattering.",
        "positive": "Decoherence Effects Break Reciprocity in Matter Transport: The decoherence of quantum states defines the transition between the quantum\nworld and classical physics. Decoherence or, analogously, quantum mechanical\ncollapse events pose fundamental questions regarding the interpretation of\nquantum mechanics and are technologically relevant because they limit the\ncoherent information processing performed by quantum computers. We have\ndiscovered that the transition regime enables a novel type of matter transport.\nApplying this discovery, we present nanoscale devices in which decoherence,\nmodeled by random quantum jumps, produces fundamentally novel phenomena by\ninterrupting the unitary dynamics of electron wave packets. Noncentrosymmetric\nconductors with mesoscopic length scales act as two-terminal rectifiers with\nunique properties. In these devices, the inelastic interaction of itinerant\nelectrons with impurities acting as electron trapping centers leads to a novel\nsteady state characterized by partial charge separation between the two leads,\nor, in closed circuits to the generation of persistent currents. The interface\nbetween the quantum and the classical worlds therefore provides a novel\ntransport regime of value for the realization of a new category of mesoscopic\nelectronic devices."
    },
    {
        "anchor": "Adiabatic theory of SET and RESET transitions: We develop a phenomenological theory of pulse induced phase transformations\nbehind the SET (from high to low resistive state) and RESET (backward)\nprocesses in nonvolatile memory. We show that in modern era devices, both\nevolve in the adiabatic regime with energy deposition time much shorter than\nthat of thermalization. They are however different by the operating modes:\nvoltage source driven for SET and current source driven for RESET. The\ncharacteristic temperatures and transition rates are expressed through material\nand process parameters.",
        "positive": "Observation of undercooling in a levitated nanoscale liquid Au droplet: We investigate melting and undercooling in nanoscale (radius ~100 nm) gold\nparticles that are levitated in a quadrupole ion (Paul) trap in a high vacuum\nenvironment. The particle is heated via laser illumination and probed using two\nmain methods. Firstly, measurements of its mass are used to determine the\nevaporation rate during illumination and infer the temperature of the particle.\nSecondly, direct optical measurements show that the light scattered from the\nparticle is significantly different in its liquid and solid phases. The\nparticle is repeatedly heated across its melting transition, and the dependence\nof heating behavior on particle size is investigated. Undercooling -- the\npersistence of a liquid state below the melting temperature -- is induced via\nmulti-stage laser pulses. The extent of undercooling is explored and compared\nto theoretical predictions."
    },
    {
        "anchor": "Ballistic Spin Resonance: The phenomenon of spin resonance has had far reaching influence since its\ndiscovery nearly 70 years ago. Electron spin resonance (ESR) driven by high\nfrequency magnetic fields has informed our understanding of quantum mechanics,\nand finds application in fields as diverse as medicine and quantum information.\nSpin resonance induced by high frequency electric fields, known as electric\ndipole spin resonance (EDSR), has also been demonstrated recently. EDSR is\nmediated by spin-orbit interaction (SOI), which couples the spin degree of\nfreedom and the momentum vector. Here, we report the observation of a novel\nspin resonance due to SOI that does not require external driving fields.\nBallistic spin resonance (BSR) is driven by an internal spin-orbit field that\nacts upon electrons bouncing at gigaHertz frequencies in narrow channels of\nultra-clean two-dimensional electron gas (2DEG). BSR is manifested in\nelectrical measurements of pure spin currents as a strong suppression of spin\nrelaxation length when the motion of electrons is in resonance with spin\nprecession. These findings point the way to gate-tunable coherent spin\nrotations in ballistic nanostructures without external a.c. fields.",
        "positive": "Domain Patterns in the Microwave-Induced Zero-Resistance State: It has been proposed that the microwave-induced ``zero-resistance''\nphenomenon, observed in a GaAs two-dimensional electron system at low\ntemperatures in moderate magnetic fields, results from a state with multiple\ndomains, in which a large local electric field $\\bE(\\br)$ is oriented in\ndifferent directions. We explore here the questions of what may determine the\ndomain arrangement in a given sample, what do the domains look like in\nrepresentative cases, and what may be the consequences of domain-wall\nlocalization on the macroscopic dc conductance. We consider both effects of\nsample boundaries and effects of disorder, in a simple model, which has a\nconstant Hall conductivity, and is characterized by a Lyapunov functional."
    },
    {
        "anchor": "Chirality-dependent spin current generation in a helimagnet: zero-field\n  probe of chirality: In a magnetic texture, the spin of a conduction electron is forced to be\naligned to the localized moment. As a result, the topology of the magnetic\ntexture affects the electron dynamics in nontrivial ways. A representative\nexample is the topological Hall effect in noncoplanar spin textures with finite\nspin chirality. While propagating in the noncoplanar spin texture, electrons\nacquire Berry phase, and their motion is deflected as if they were in a\nmagnetic field. Here, we report a distinct Berry phase effect in a coplanar\nhelimagnet: the spin moment of the conduction electron is polarized under\nelectric currents depending on the chirality of the helimagnet. The accumulated\nspin polarization works as a source of spin current, and the chirality can be\ndetected by the inverse spin Hall mechanism. The functionality allows us to\nread out the chirality without magnetic fields, and therefore paves the way to\nfuture helimagnet-based spintronics.",
        "positive": "Quasiparticle interference of the Fermi arcs and surface-bulk\n  connectivity of a Weyl semimetal: Weyl semimetals host topologically protected surface states, with arced Fermi\nsurface contours that are predicted to propagate through the bulk when their\nmomentum matches that of the surface projections of the bulk's Weyl nodes. We\nuse spectroscopic mapping with a scanning tunneling microscope to visualize\nquasi-particle scattering and interference at the surface of the Weyl semimetal\nTaAs. Our measurements reveal 10 different scattering wave vectors, which can\nbe understood and precisely reproduced with a theory that takes into account\nthe shape, spin texture, and momentum-dependent propagation of the Fermi arc\nsurface states into the bulk. Our findings provide evidence that Weyl nodes act\nas sinks for electron transport on the surface of these materials."
    },
    {
        "anchor": "Lower limit on the achievable temperature in resonator-based sideband\n  cooling: A resonator can be effectively used as a cooler for another linear oscillator\nwith a much smaller frequency. A huge cooling effect, which could be used to\ncool a mechanical oscillator below the energy of quantum fluctuations, has been\npredicted by several authors. However, here we show that there is a lower limit\nT* on the achievable temperature that was not considered in previous works and\ncan be higher than the quantum limit in realistic experimental realizations. We\nalso point out that the decay rate of the resonator, which previous studies\nstress should be small, must be larger than the decay rate of the cooled\noscillator for effective cooling.",
        "positive": "Isospin Blockade in Transport through Vertical Double Quantum Dots: We study the spectrum and the transport properties of two identical,\nvertically coupled quantum dots in a perpendicular magnetic field. We find\ncorrelation-induced energy crossings in a magnetic field sweep between states\ndiffering only in the vertical degree of freedom. Considering the influence of\na slight asymmetry between the dots caused by the applied source-drain voltage\nin vertical transport experiments these crossings convert to anticrossings\naccompanied by the build-up of charge polarization which is tunable by the\nperpendicular magnetic field. The polarization strongly affects the vertical\ntransport through the double quantum dot and is manifest in an isospin blockade\nand the appearance of negative differential conductances in the magnetic field\nrange where the charge localization occurs."
    },
    {
        "anchor": "Hole maximum density droplets of an antidot in strong magnetic fields: We investigate a quantum antidot in the integer quantum Hall regime (the\nfilling factor is two) by using a Hartree-Fock approach and by transforming the\nelectron antidot into a system which confines holes via an electron-hole\ntransformation. We find that its ground state is the maximum density droplet of\nholes in certain parameter ranges. The competition between electron-electron\ninteractions and the confinement potential governs the properties of the hole\ndroplet such as its spin configuration. The ground-state transitions between\nthe droplets with different spin configurations occur as magnetic field varies.\nFor a bell-shape antidot containing about 300 holes, the features of the\ntransitions are in good agreement with the predictions of a recently proposed\ncapacitive interaction model for antidots as well as recent experimental\nobservations. We show this agreement by obtaining the parameters of the\ncapacitive interaction model from the Hartree-Fock results. An inverse\nparabolic antidot is also studied. Its ground-state transitions, however,\ndisplay different magnetic-field dependence from that of a bell-shape antidot.\nOur study demonstrates that the shape of antidot potential affects its physical\nproperties significantly.",
        "positive": "Cavity-enhanced measurements of defect spins in silicon carbide: The identification of new solid-state defect qubit candidates in widely used\nsemiconductors has the potential to enable the use of nanofabricated devices\nfor enhanced qubit measurement and control operations. In particular, the\nrecent discovery of optically active spin states in silicon carbide thin films\noffers a scalable route for incorporating defect qubits into on-chip photonic\ndevices. Here we demonstrate the use of 3C silicon carbide photonic crystal\ncavities for enhanced excitation of color center defect spin ensembles in order\nto increase measured photoluminescence signal count rates, optically detected\nmagnetic resonance signal intensities, and optical spin initialization rates.\nWe observe up to a factor of 30 increase in the photoluminescence and ODMR\nsignals from Ky5 color centers excited by cavity resonant excitation and\nincrease the rate of ground-state spin initialization by approximately a factor\nof two. Furthermore, we show that the small excitation mode volume and enhanced\nexcitation and collection efficiencies provided by the structures can be used\nto study inhomogeneous broadening in defect qubit ensembles. These results\nhighlight some of the benefits that nanofabricated devices offer for\nengineering the local photonic environment of color center defect qubits to\nenable applications in quantum information and sensing."
    },
    {
        "anchor": "Transition to a supersolid phase in a two-dimensional dilute gas of\n  electron-hole pairs: Using coherent-state formalism (the Keldysh formalism), the article describes\na transition from a homogeneous superfluid state to a supersolid state in a\ntwo-dimensional dilute gas of electron-hole pairs with spatially separated\ncomponents. Such a transition is heralded by the appearance of a roton-type\nminimum in the collective excitation spectrum, which touches the abscissa axis\nas the distance between the layers or the pair density increases. This signals\nthe instability of the system with respect to the appearance of a spatial\nmodulation of the pair density. It has been found that a first-order transition\nto a hexagonal supersolid phase takes place a little earlier. A theory without\nphenomenological constants has been developed for an arbitrary relation between\nthe effective masses of an electron and a hole. A phase diagram for the system\nhas been plotted in the variables \"the chemical potential of pairs - the\ndistance between the layers\". It has been shown that there is a jump in the\naverage density of the condensate during the phase transition. It has been\nestablished that with an increase in the chemical potential, the inhomogeneous\nphase breaks up into high-density regions surrounded by lines at which the\ndensity becomes zero, with these lines forming a continuous network.",
        "positive": "MoS$_2$ flake as a van der Waals homostructure: luminescence properties\n  and optical anisotropy: We investigated multilayer plates made by exfoliation from a high-quality\nMoS$_2$ crystal and reveal that they represent a new object - van der Waals\nhomostructure consisting of a bulk core and a few detached monolayers on its\nsurface. This architecture comprising elements with different electron band\nstructure leads to specific luminescence, when the broad emission band from the\ncore is cut by the absorption peaks of strong exciton resonances in the surface\nmonolayers. The exfoliated flakes exhibit strong optical anisotropy. We have\nobserved a conversion of normally incident light polarization to $15\\%$ in\ntransmission geometry. This background effect is due to fluctuations of the c\naxis relative to the normal, whereas the pronounced resonance contribution is\nexplained by the polarization anisotropy of excitons localized in the stripes\nof dissected surface monolayers."
    },
    {
        "anchor": "Fusion protocol for Majorana modes in coupled quantum dots: In a recent breakthrough experiment [Nature (London) 614, 445 (2023)],\nsignatures of Majorana zero modes have been observed in tunnel spectroscopy for\na minimal Kitaev chain constructed from coupled quantum dots. However, as Ising\nanyons, Majoranas' most fundamental property of non-Abelian statistics is yet\nto be detected. Moreover, the minimal Kitaev chain is qualitatively different\nfrom topological superconductors in that it supports Majoranas only at a sweet\nspot. Therefore, it is not obvious whether non-Abelian characteristics such as\nbraiding and fusion can be demonstrated in this platform with a reasonable\nlevel of robustness. In this work, we theoretically propose a protocol for\ndetecting the Majorana fusion rules in an artificial Kitaev chain consisting of\nfour quantum dots. In contrast with the previous proposals for\nsemiconductor-superconductor hybrid nanowire platforms, here we do not rely on\nmesoscopic superconducting islands, which are difficult to implement in quantum\ndot chains. To show the robustness of the fusion protocol, we discuss the\neffects of three types of realistic imperfections on the fusion outcomes, e.g.,\ndiabatic errors, dephasing errors, and calibration errors. We also propose a\nfermion parity readout scheme using quantum capacitance. Our work will shed\nlight on future experiments on detecting the non-Abelian properties of Majorana\nmodes in a quantum dot chain.",
        "positive": "Zero-index and Topology in 1D Phononic Metamaterials with Negative Mass\n  and Negative Coupling: Phononic metamaterials have attracted extensive attention since they are\nexibly adjustable to control the phonon transmission. In this work, we study a\none-dimensional phononic metamaterial, made of mechanical resonant oscillators\nand chiral couplings. We show that by design, the oscillator mass and\ninter-oscillator coupling, although both are positive naturally, can be either\nsingle negative or double negative effectively within a certain frequency\nrange. At the frequency where the effective mass and coupling are both\ninfinite, a flat band emerges that will induce an extremely high density of\nstates. At the critical point of band degeneracy, a Dirac-like point emerges\nwhere both effective mass and the inverse of effective coupling are\nsimultaneously zero, so that zero index is realized for phonons. Moreover, the\nphononic topological phase transition is observed that the phononic band gap\nswitches between single mass-negative and single coupling-negative regime. As a\nconsequence, a topological interface state is identified, well explained by the\ntheory."
    },
    {
        "anchor": "Impact of spin-orbit coupling on quantum Hall nematic phases: Anisotropic charge transport is observed in a two-dimensional (2D) hole\nsystem in a perpendicular magnetic field at filling factors nu=7/2, nu=11/2,\nand nu=13/2 at low temperature. In stark contrast, the transport at nu=9/2 is\nisotropic for all temperatures. Isotropic hole transport at nu=7/2 is restored\nfor sufficiently low 2D densities or an asymmetric confining potential. The\ndensity and symmetry dependences of the observed anisotropies suggest that\nstrong spin-orbit coupling in the hole system contributes to the unusual\ntransport behavior.",
        "positive": "Polar Coupling Enabled Nonlinear Optical Filtering at\n  MoS$_2$/Ferroelectric Heterointerfaces: Complex oxide heterointerfaces and van der Waals heterostructures present two\nversatile but intrinsically different platforms for exploring emergent quantum\nphenomena and designing new functionalities. The rich opportunity offered by\nthe synergy between these two classes of materials, however, is yet to be\ncharted. Here, we report an unconventional nonlinear optical filtering effect\nresulting from the interfacial polar alignment between monolayer MoS$_2$ and a\nneighboring ferroelectric oxide thin film. The second harmonic generation\nresponse at the heterointerface is either substantially enhanced or almost\nentirely quenched by an underlying ferroelectric domain wall depending on its\nchirality, and can be further tailored by the polar domains. Unlike the\nextensively studied coupling mechanisms driven by charge, spin, and lattice,\nthe interfacial tailoring effect is solely mediated by the polar symmetry, as\nwell explained via our density functional theory calculations, pointing to a\nnew material strategy for the functional design of nanoscale reconfigurable\noptical applications."
    },
    {
        "anchor": "On-chip magnetic cooling of a nanoelectronic device: We demonstrate significant cooling of electrons in a nanostructure below 10\nmK by demagnetisation of thin-film copper on a silicon chip. Our approach\novercomes the typical bottleneck of weak electron-phonon scattering by coupling\nthe electrons directly to a bath of refrigerated nuclei, rather than cooling\nvia phonons in the host lattice. Consequently, weak electron-phonon scattering\nbecomes an advantage. It allows the electrons to be cooled for an\nexperimentally useful period of time to temperatures colder than the dilution\nrefrigerator platform, the incoming electrical connections, and the host\nlattice. There are efforts worldwide to reach sub-millikelvin electron\ntemperatures in nanostructures to study coherent electronic phenomena and\nimprove the operation of nanoelectronic devices. On-chip magnetic cooling is a\npromising approach to meet this challenge. The method can be used to reach low,\nlocal electron temperatures in other nanostructures, obviating the need to\nadapt traditional, large demagnetisation stages. We demonstrate the technique\nby applying it to a nanoelectronic primary thermometer that measures its\ninternal electron temperature. Using an optimised demagnetisation process, we\ndemonstrate cooling of the on-chip electrons from 9 mK to below 5 mK for over\n1000 seconds.",
        "positive": "Aharonov-Bohm Oscillations in Minimally Twisted Bilayer Graphene: We investigate transport in the network of valley Hall states that emerges in\nminimally twisted bilayer graphene under interlayer bias. To this aim, we\nconstruct a scattering theory that captures the network physics. In the absence\nof forward scattering, symmetries constrain the network model to a single\nparameter that interpolates between one-dimensional chiral zigzag modes and\npseudo-Landau levels. Moreover, we show how the coupling of zigzag modes\naffects magnetotransport. In particular, we find that scattering between\nparallel zigzag channels gives rise to Aharonov-Bohm oscillations that are\nrobust against temperature, while coupling between zigzag modes propagating in\ndifferent directions leads to Shubnikov-de Haas oscillations that are smeared\nout at finite temperature."
    },
    {
        "anchor": "Crossover of ballistic, hydrodynamic, and diffusive phonon transport in\n  suspended graphene: Hydrodynamic phonon transport was recently predicted as an important regime\nfor phonon transport in graphitic materials. Many of past studies on\nhydrodynamic phonon transport have focused on the cases where the hydrodynamic\nregime predominates over other regimes such that hydrodynamic features can be\nclearly observed. However, this often requires stringent conditions of\ntemperature and sample size. In many cases, a single regime does not dominate\nother regimes, but all three regimes - ballistic, hydrodynamic, and diffusive\nregimes - exist to some extent. Here we assess the extent of three regimes by\ncomparing momentum destruction rates by three different mechanisms, each of\nwhich represents a different regime: diffuse boundary scattering without\ninternal phonon scattering (ballistic regime), diffuse boundary scattering\ncombined with normal scattering (hydrodynamic regime), and umklapp scattering\n(diffusive regime). We solve the Peierls-Boltzmann equation with an ab initio\nfull scattering matrix using a deviational Monte Carlo method. We sample\ndistribution functions of ballistic and scattered particles separately, and\nthereby compare the momentum destruction rates by the three different\nmechanisms. Using this framework, we discuss a well-known phenomenon of\nballistic-to-hydrodynamic crossover, called phonon Knudsen minimum.",
        "positive": "Weak antilocalization of holes in HgTe quantum wells with a normal\n  energy spectrum: The results of experimental study of interference induced magnetoconductivity\nin narrow HgTe quantum wells of hole-type conductivity with a normal energy\nspectrum are presented. Interpretation of the data is performed with taking\ninto account the strong spin-orbit splitting of the energy spectrum of the\ntwo-dimensional hole subband. It is shown that the phase relaxation time found\nfrom the analysis of the shape of magnetoconductivity curves for the relatively\nlow conductivity when the Fermi level lies in the monotonic part of the energy\nspectrum of the valence band behaves itself analogously to that observed in\nnarrow HgTe quantum wells of electron-type conductivity. It increases in\nmagnitude with the increasing conductivity and decreasing temperature following\nthe $1/T$ law. Such a behavior corresponds to the inelasticity of\nelectron-electron interaction as the main mechanism of the phase relaxation and\nagrees well with the theoretical predictions. For the higher conductivity,\ndespite the fact that the dephasing time remains inversely proportional to the\ntemperature, it strongly decreases with the increasing conductivity. It is\npresumed that a nonmonotonic character of the hole energy spectrum could be the\nreason for such a peculiarity. An additional channel of the inelastic\ninteraction between the carriers in the main and secondary maxima occurs when\nthe Fermi level arrives the secondary maxima in the depth of the valence."
    },
    {
        "anchor": "Weak localization, Aharonov-Bohm oscillations and decoherence in arrays\n  of quantum dots: Combining scattering matrix theory with non-linear $\\sigma$-model and Keldysh\ntechnique we develop a unified theoretical approach enabling one to\nnon-perturbatively study the effect of electron-electron interactions on weak\nlocalization and Aharonov-Bohm oscillations in arbitrary arrays of quantum\ndots. Our model embraces (i) weakly disordered conductors (ii) strongly\ndisordered conductors and (iii) metallic quantum dots. In all these cases at $T\n\\to 0$ the electron decoherence time is found to saturate to a finite value\ndetermined by the universal formula which agrees quantitatively with numerous\nexperimental results. Our analysis provides overwhelming evidence in favor of\nelectron-electron interactions as a universal mechanism for zero temperature\nelectron decoherence in disordered conductors.",
        "positive": "Effect of phonon scattering by surface roughness on the universal\n  thermal conductance: The effect of phonon scattering by surface roughness on the thermal\nconductance in mesoscopic systems at low temperatures is calculated using full\nelasticity theory. The low frequency behavior of the scattering shows novel\npower law dependences arising from the unusual properties of the elastic modes.\nThis leads to new predictions for the low temperature depression of the thermal\nconductance below the ideal universal value. Comparison with the data of Schwab\net al. [Nature 404, 974 (2000)] suggests that surface roughness on a scale of\nthe width of the thermal pathway is important in the experiment."
    },
    {
        "anchor": "Nonlinear response of a driven vibrating nanobeam in the quantum regime: We analytically investigate the nonlinear response of a damped doubly clamped\nnanomechanical beam under static longitudinal compression which is excited to\ntransverse vibrations. Starting from a continuous elasticity model for the\nbeam, we consider the dynamics of the beam close to the Euler buckling\ninstability. There, the fundamental transverse mode dominates and a quantum\nmechanical time-dependent effective single particle Hamiltonian for its\namplitude can be derived. In addition, we include the influence of a\ndissipative Ohmic or super-Ohmic environment. In the rotating frame, a\nMarkovian master equation is derived which includes also the effect of the\ntime-dependent driving in a non-trivial way. The quasienergies of the pure\nsystem show multiple avoided level crossings corresponding to multiphonon\ntransitions in the resonator. Around the resonances, the master equation is\nsolved analytically using Van Vleck perturbation theory. Their lineshapes are\ncalculated resulting in simple expressions. We find the general solution for\nthe multiple multiphonon resonances and, most interestingly, a bath-induced\ntransition from a resonant to an antiresonant behavior of the nonlinear\nresponse.",
        "positive": "Parametric Correlations of Phase Shifts and Statistics of Time Delays in\n  Quantum Chaotic Scattering: Crossover between Unitary and Orthogonal\n  Symmetries: We analyse universal statistical properties of phase shifts and time delays\nfor open chaotic systems in the crossover regime of partly broken time-reversal\ninvariance. In particular, we find that the distribution of the time delay\nshows $\\tau^{-3/2}$ behavior for weakly open systems of any symmetry."
    },
    {
        "anchor": "Over-Bias Light Emission due to Higher Order Quantum Noise of a Tunnel\n  Junction: Understanding tunneling from an atomically sharp tip to a metallic surface\nrequires to account for interactions on a nanoscopic scale. Inelastic tunneling\nof electrons generates emission of photons, whose energies intuitively should\nbe limited by the applied bias voltage. However, experiments by Schull et al.\n[Phys. Rev. Lett. 102, 057401 (2009)] indicate that more complex processes\ninvolving the interaction of electrons with plasmon polaritons lead to photon\nemission characterized by over-bias energies. We propose a model of this\nobservation in analogy to dynamical Coulomb blockade, originally developed for\ntreating the electronic environment in mesoscopic circuits. We explain the\nexperimental finding quantitatively by the correlated tunneling of two\nelectrons interacting with an LRC circuit modeling the local plasmon-polariton\nmode. To explain the over-bias emission, the non-Gaussian statistics of the\ntunneling dynamics of the electrons is essential.",
        "positive": "Exciton storage in a nano-scale Aharonov-Bohm ring with electric field\n  tuning: We study analytically the optical properties of a simple model for an\nelectron-hole pair on a ring subjected to perpendicular magnetic flux and\nin-plane electric field. We show how to tune this excitonic system from\noptically active to optically dark as a function of these external fields. Our\nresults offer a simple mechanism for exciton storage and read-out."
    },
    {
        "anchor": "Switching valley filtered current directions in multi-terminal graphene\n  systems: Valley filtering processes have been explored in different graphene-based\nconfigurations and scenarios to control transport responses. Here we propose\ngraphene multi-terminal set-ups properly designed to obtain valley filtered\ncurrents in a broad range of energy, besides the possibility of controlling\ntheir directions. We explore graphene systems with extended mechanical\nfold-like deformations as an opportunity to enhance valley filtered\ntransmission. The mixing between the electronic confinement effects due to a\nmagnetic field and strain results in a selective drive of the current\ncomponents in the quantum Hall regime. We adopt the mode-matching method within\nthe Green's function formalism, allowing the direct analysis of the strain\neffect on each valley transmission. We estimate a threshold map of confinement\nparameters, characterized by the magnetic, deformation, and set-up lengths, to\noptimize valley filter transport processes and the proper switch of the valley\npolarized current directions.",
        "positive": "Solving NP-hard problems with bistable polaritonic networks: A lattice of locally bistable driven-dissipative cavity polaritons is found\ntheoretically to effectively simulate the Ising model, also enabling an\neffective transverse field. We benchmark the system performance for spin glass\nproblems, and study the scaling of the ground state energy deviation and\nsuccess probability as a function of system size. As particular examples we\nconsider NP-hard problems embedded in the Ising model, namely graph\npartitioning and the knapsack problem. We find that locally bistable polariton\nnetworks act as classical simulators for solving optimization problems, which\ncan potentially present an improvement within the exponential complexity class."
    },
    {
        "anchor": "Universal set of quantum gates for double-dot spin qubits with fixed\n  interdot coupling: We propose a set of universal gate operations for the singlet-triplet qubit\nrealized by two electron spins in a double quantum dot, in the presence of a\nfixed inhomogeneous magnetic field. All gate operations are achieved by\nswitching the potential offset between the two dots with an electrical bias,\nand do not require time-dependent control of the tunnel coupling between the\ndots. We analyze the two-electron dynamics and calculate the effective qubit\nrotation angle as a function of the applied electric bias. We present explicit\ngate sequences for single-qubit rotations about two orthogonal axes, and a CNOT\ngate sequence, completing the universal gate set.",
        "positive": "Molecular Diffusion Replaces Capillary Pumping in Phase-Change Driven\n  Nanopumps: Nano-scale fluid transport has vast applications spanning from water\ndesalination to biotechnology [1,2]. It is possible to pump fluids in\nnano-conduits using pressure gradients [3], thermal methods [4], electric [5,6]\nand magnetic fields [7], and with manipulations of surface chemistry and\nelectric fields [8-10]. Inspired by the capillary-driven phase change heat\ntransfer devices, we present a phase-change driven nanopump operating almost\nisothermally. Meticulous computational experiments on different sized nanopumps\nrevealed efficient operation of the pump despite the reduction in system size\nthat extinguishes capillary pumping by annihilating the liquid meniscus\nstructures. Measuring the density distribution of liquid in cross sections near\nto the evaporating and condensing liquid-vapor interfaces, we discovered that\nphase change induced molecular scale mass diffusion mechanism replaces the\ncapillary pumping in the absence of meniscus structures. Therefore, proposed\npumps can serve as a part of both nanoelectromechanical (NEMS) and\nmicroelectromechanical systems (MEMS) with similar working efficiencies, and\ncan be used for continuous gas separation applications."
    },
    {
        "anchor": "Hedgehog orbital texture in p-type tellurium and the antisymmetric\n  nonreciprocal Hall response: Tellurium is a gyrotropic, p-type Weyl semiconductor with remarkable\nelectronic, optical, and transport properties. It has been argued that some of\nthese properties might stem from Weyl nodes at crossing points in the band\nstructure, and their nontrivial topological textures. However, Weyl nodes in\ntime-reversal invariant semiconductors are split up in energy, rather than in\nmomentum, and located deep below (far above) the top (bottom) of the valence\n(conduction) band, challenging such an interpretation. Here, instead, we use a\n4-band kp Hamiltonian for $p-$type tellurium to show how the k-dependent\nspin-orbit interaction mixes up the top two (Weyl node free) and bottom two\n(Weyl node containing) valence bands, generating a 3D hedgehog orbital magnetic\ntexture at the uppermost valence band, accessible to transport already at the\nlowest doping. Hedgehog textures are important signatures of Weyl fermion\nphysics in general and in the context of condensed matter physics arise form\nthe carriers' wave packet rotation being locked to their propagation\nwavevector. For spatially dispersive media, such an induced hedgehog\ntexture/carrier rotation stabilizes two novel, nonreciprocal and antisymmetric\ncomponents to the Hall transport within different weak-localization\n(antilocalization) relaxation regimes: the anomalous and planar Hall effects,\nusually forbidden by time reversal symmetry. Our AC magnetotransport\nmeasurements on Sn-doped tellurium confirm the theoretical predictions and our\nwork demonstrates how Weyl signatures generally appear in transport on\nenantiomorphic materials with natural optical activity.",
        "positive": "Quantum multifractality in thermal conduction across random interfaces: Self-affine morphology of random interfaces governs their functionalities\nacross tribological, geological, (opto-)electrical and biological applications.\nHowever, the knowledge of how energy carriers or generally classical/quantum\nwaves interact with structural irregularity is still incomplete. In this work,\nwe study vibrational energy transport through random interfaces exhibiting\ndifferent correlation functions on the two-dimensional hexagonal lattice. We\nshow that random interfaces at the atomic scale are Cantor composites populated\non geometrical fractals, thus multifractals, and calculate their quantized\nconductance using atomistic approaches. We obtain a universal scaling law,\nwhich contains self-similarity for mass perturbation, and exponential scaling\nof structural irregularity quantified by fractal dimension. The multifractal\nnature and Cantor-composite picture may also be extendable to charge and photon\ntransport across random interfaces."
    },
    {
        "anchor": "Atomistic modelling of frictional anisotropy of palladium nanoparticles\n  on graphene: This article is a continuation of our previous studies of the frictional\nanisotropy of metal nanoparticles on the surface of a graphene substrate for\nother temperature conditions. The friction force acting on palladium\nnanoparticles on a graphene sheet in various lateral directions is investigated\nusing classical molecular dynamics modelling. Anisotropy is studied at high\nsliding speeds of nanoparticles consisting of 10000 atoms on the surface of\ngraphene. The effect of incommensurability and short-range order of the contact\nsurfaces of nanoparticles, as well as the graphene deformation lead to the\nabsence of an expressed angular dependence of the friction force.",
        "positive": "Strain-tunable magnetic anisotropy in monolayer CrCl$_3$, CrBr$_3$, and\n  CrI$_3$: Recent observation of intrinsic ferromagnetism in two-dimensional (2D)\nCrI$_3$ is associated with the large magnetic anisotropy due to strong\nspin-orbit coupling (SOC) of I. Magnetic anisotropy energy (MAE) defines the\nstability of magnetization in a specific direction with respect to the crystal\nlattice and is an important parameter for nanoscale applications. In this work\nwe apply the density functional theory to study the strain dependence of MAE in\n2D monolayer chromium trihalides CrX$_3$ (with X = Cl, Br, and I). Detailed\ncalculations of their energetics, atomic structures and electronic structures\nunder the influence of a biaxial strain $\\varepsilon$ have been carried out. It\nis found that all three compounds exhibit ferromagnetic ordering at the ground\nstate (with $\\varepsilon$=0) and upon applying a compressive strain, phase\ntransition to antiferromagnetic state occurs. Unlike in CrCl$_3$ and CrBr$_3$,\nthe electronic band gap in CrI$_3$ increases when a tensile strain is applied.\nThe MAE also exhibits a strain dependence in the chromium trihalides: it\nincreases when a compressive strain is applied in CrI$_3$, while an opposite\ntrend is observed in the other two compounds. In particular, the MAE of CrI$_3$\ncan be increased by 47\\% with a compressive strain of $\\varepsilon$ = 5\\%."
    },
    {
        "anchor": "Fluctuating-time and full counting statistics for quantum transport in a\n  system with internal telegraphic noise: Many molecular junctions display stochastic telegraphic switching between two\ndistinct current values, which is therefore an important source of fluctuations\nin nanoscale quantum transport. We investigate electronic fluctuations arising\nvia Markovian master equations; identifying regions of non-renewal behavior due\nto telegraphic switching. Non-renewal behavior is characterized by the\nemergence of correlations between successive first-passage times of detection\nin one of the leads. Our method of including telegraphic switching is general\nfor any source-molecule-drain setup, but we consider three specific cases. In\nthe first, we model stochastic transitions between an Anderson impurity with\nand without an applied magnetic field $B$. The last two scenarios couple the\nelectronic level to a single vibrational mode via the Holstein model. We then\nstochastically switch between two vibrational conformations, with different\nelectron-phonon coupling and vibrational frequency, which corresponds to\ndifferent molecular conformations. Finally, we model the molecule attaching and\ndetaching from an electrode by switching between two different\nmolecule-electrode coupling strengths. We find, for all three cases, that\nincluding the telegraph process in the master equation induces relatively\nstrong positive correlations, with Pearson coefficient $p \\approx 0.5$, between\nsuccessive first-passage times. These correlations only appear, however, when\nthere is telegraphic switching between two significantly different transport\nscenarios, and we show that it arises from the underlying physics of the model.\nWe also find that, in order for correlations to appear, the switching rate\n$\\nu$ must be much smaller than the rate of electron transfer $\\gamma$.",
        "positive": "A quantum model for voltage noise: Theory and Experiments: Although the Fluctuation-Dissipation framework is a first step to get a\nquantum model for electrical noise, the merging of displacement and conduction\ncurrents into the sole current of a series notion like the resistance R(f) does\nnot help in it this task. Used to handle these currents as orthogonal\ncomponents in electromagnetic waves, the usage of the impedance\nZ(jf)=R(f)+jX(f) for the noisy device hides the way it interacts with its\nthermal bath. In contrast to this, the admittance Y(jf) is a parallel notion\ndirectly linked with the aforementioned interaction that has led us to develop\na discrete model for current fluctuations where single electrons randomly\nshuttling between any pair of terminals generate the voltage noise we can\nmeasure between them."
    },
    {
        "anchor": "Green's Function Method for Line Defects and Gapless Modes in\n  Topological Insulators : Beyond Semiclassical Approach: Defects which appear in heterostructure junctions involving topological\ninsulators are sources of gapless modes governing the low energy properties of\nthe systems, as recently elucidated by Teo and Kane [Physical Review B82,\n115120 (2010)]. A standard approach for the calculation of topological\ninvariants associated with defects is to deal with the spatial inhomogeneity\nraised by defects within a semiclassical approximation. In this paper, we\npropose a full quantum formulation for the topological invariants\ncharacterizing line defects in three-dimensional insulators with no symmetry by\nusing the Green's function method. On the basis of the full quantum treatment,\nwe demonstrate the existence of a nontrivial topological invariant in the\ntopological insulator-ferromagnet tri-junction systems, for which a\nsemiclassical approximation fails to describe the topological phase. Also, our\napproach enables us to study effects of electron-electron interactions and\nimpurity scattering on topological insulators with spatial inhomogeneity which\ngives rise to the Axion electrodynamics responses.",
        "positive": "Fingerprints of tilted Dirac cones on the RKKY exchange interaction in\n  8-Pmmn Borophene: We theoretically investigate the indirect signatures of the tilted\nanisotropic Dirac cones on Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange\ninteraction in a two dimensional polymorph of boron atoms. Unlike the case of\nisotropic non-tilted Dirac material-graphene, here we observe that the tilting\nof the Dirac cones exhibits a significant impact on the RKKY exchange\ninteraction in terms of the suppression of oscillation frequency. The reason\ncan be attributed to the behavior of the Fermi level and the corresponding\ndensity of states with respect to the tilting parameter. The direct measurement\nof the period of the RKKY interaction can thus be a possible probe of the tilt\nparameter associated with the tilted Dirac cones. We also obtain the direction\ndependent analytical expressions of the RKKY exchange interaction, in terms of\nMeijer G-function. However, the effects due to tilting of the Dirac cones on\nthe RKKY interaction depend on the spatial alignments of the two magnetic\nimpurities with respect to the direction of tilting."
    },
    {
        "anchor": "Well-width dependence of valley splitting in Si/SiGe quantum wells: The valley splitting in Si two-dimensional electron systems is studied using\nSi/SiGe single quantum wells (QWs) with different well widths. The energy gaps\nfor 4 and 5.3 nm QWs, obtained from the temperature dependence of the\nlongitudinal resistivity at the Landau level filling factor $\\nu=1$, are much\nlarger than those for 10 and 20 nm QWs. This is consistent with the well-width\ndependence of the bare valley splitting estimated from the comparison with the\nZeeman splitting in the Shubnikov-de Haas oscillations.",
        "positive": "Tunable Thermal Conduction in Graphane Nanoribbons: Graphane and graphene are both two-dimensional materials but of different\nbonding configurations, which can result in distinct thermal conduction\nproperties. We simulate thermal conduction in graphane nanoribbons (GANRs)\nusing the nonequilibrium Green's function method. It is found that GANRs have\nlower ballistic thermal conductance and stronger thermal conductance anisotropy\nthan the graphene counterparts. Furthermore, hydrogen vacancies of GANRs\nconsiderably suppress thermal conduction, accompanied by enhanced thermal\nconductance anisotropy. The tunable thermal conduction, realized by controlling\nthe width, edge shape and hydrogen vacancy concentration of GANRs, could be\nuseful for thermal management and thermoelectric applications."
    },
    {
        "anchor": "High-temperature behaviour of supported graphene: electron-phonon\n  coupling and substrate-induced doping: One of the salient features of graphene is the very high carrier mobility\nthat implies tremendous potential for use in electronic devices. Unfortunately,\ntransport measurements find the expected high mobility only in freely suspended\ngraphen. When supported on a surface, graphene shows a strongly reduced\nmobility, and an especially severe reduction for temperatures above 200 K. A\ntemperature-dependent mobility reduction could be explained by scattering of\ncarriers with phonons, but this is expected to be weak for pristine,\nweakly-doped graphene. The mobility reduction has therefore been ascribed to\nthe interaction with confined ripples or substrate phonons. Here we study the\ntemperature-dependent electronic structure of supported graphene by\nangle-resolved photoemission spectroscopy, a technique that can reveal the\norigin of the phenomena observed in transport measurements. We show that the\nelectron-phonon coupling for weakly-doped, supported graphene on a metal\nsurface is indeed extremely weak, reaching the lowest value ever reported for\nany material. However, the temperature-dependent dynamic interaction with the\nsubstrate leads to a complex and dramatic change in the carrier type and\ndensity that is relevant for transport. Using ab initio molecular dynamics\nsimulations, we show that these changes in the electronic structure are mainly\ncaused by fluctuations in the graphene-substrate distance.",
        "positive": "Monte Carlo simulation of spin polarized transport in nanowires and 2-D\n  channels of III-V semiconductors: We simulated spin polarized transport of electrons along III-V nanowires and\ntwo dimensional III-V channels using semi classical Monte Carlo method.\nProperties of spin relaxation length have been investigated in different III-V\nzinc-blende materials at various conditions, such as, temperature, external\nfield etc. Spin dephasing in III-V channels is caused due to D'yakonov-Perel\n(DP) relaxation and due to Elliott-Yafet (EY) relaxation. Spin dephasing length\nin nanowire is found to be greater than that in 2-D channel."
    },
    {
        "anchor": "Microwave spectroscopy on a double quantum dot with an on-chip Josephson\n  oscillator: We present measurements on microwave spectroscopy on a double quantum dot\nwith an on-chip microwave source. The quantum dots are realized in the\ntwo-dimensional electron gas of an AlGaAs/GaAs heterostructure and are weakly\ncoupled in series by a tunnelling barrier forming an 'ionic' molecular state.\nWe employ a Josephson oscillator formed by a long Nb/Al-AlO$_x$/Nb junction as\na microwave source. We find photon-assisted tunnelling sidebands induced by the\nJosephson oscillator, and compare the results with those obtained using an\nexternally operated microwave source.",
        "positive": "Switchable large-gap quantum spin Hall state in two-dimensional\n  MSi$_2$Z$_4$ materials class: Quantum spin Hall (QSH) insulators exhibit spin-polarized conducting edge\nstates that are topologically protected from backscattering and offer unique\nopportunities for addressing fundamental science questions and device\napplications. Finding viable materials that host such topological states,\nhowever, remains a challenge. Here by using in-depth first-principles\ntheoretical modeling, we predict large bandgap QSH insulators in recently\nbottom-up synthesized two-dimensional (2D) MSi$_2$Z$_4$ (M = Mo or W and Z = P\nor As) materials family with $1T^\\prime$ structure. A structural distortion in\nthe $2H$ phase drives a band inversion between the metal (Mo/W) $d$ and $p$\nstates of P/As to realize spinless Dirac cone states without spin-orbit\ncoupling. When spin-orbit coupling is included, a hybridization gap as large as\n$\\sim 204$ meV opens up at the band crossing points, realizing spin-polarized\nconducting edge states with nearly quantized spin Hall conductivity. We also\nshow that the inverted band gap is tunable with a vertical electric field which\ndrives a topological phase transition from the QSH to a trivial insulator with\nRashba-like edge states. Our study identifies 2D MSi$_2$Z$_4$ materials family\nwith $1T^\\prime$ structure as large bandgap, tunable QSH insulators with\nprotected spin-polarized edge states and large spin-Hall conductivity."
    },
    {
        "anchor": "Induced magnetization and power loss for a periodically driven system of\n  ferromagnetic nanoparticles with randomly oriented easy axes: We study the effect of an elliptically polarized magnetic field on a system\nof non-interacting, single-domain ferromagnetic nanoparticles characterized by\na uniform distribution of easy axis directions. Our main goal is to determine\nthe average magnetization of this system and the power loss in it. In order to\ncalculate these quantities analytically, we develop a general perturbation\ntheory for the Landau-Lifshitz-Gilbert (LLG) equation and find its steady-state\nsolution for small magnetic field amplitudes. On this basis, we derive the\nsecond-order expressions for the average magnetization and power loss,\ninvestigate their dependence on the magnetic field frequency, and analyze the\nrole of subharmonic resonances resulting from the nonlinear nature of the LLG\nequation. For arbitrary amplitudes, the frequency dependence of these\nquantities is obtained from the numerical solution of this equation. The impact\nof transitions between different regimes of regular and chaotic dynamics of\nmagnetization, which can be induced in nanoparticles by changing the magnetic\nfield frequency, is examined in detail.",
        "positive": "Optically induced delocalization of electrons bound by attractive\n  potentials: Within the Floquet theory of periodically driven quantum systems, we\ndemonstrate that a circularly polarized off-resonant electromagnetic field can\ndestroy the electron states bound by three-dimensional attractive potentials.\nAs a consequence, the optically induced delocalization of bound electrons\nappears. The effect arises from the changing of topological structure of a\npotential landscape under a circularly polarized off-resonant electromagnetic\nfield which turns simply connected potentials into doubly connected ones.\nPossible manifestations of the effect are discussed for conduction electrons in\ncondensed-matter structures."
    },
    {
        "anchor": "Gradient-index electron optics in graphene pn junctions: We investigate the electron transport in smooth graphene pn junctions,\ngenerated by gradually varying electrostatic potentials. The numerically\ncalculated coherent current flow patterns can be understood largely in terms of\nsemi-classical trajectories, equivalent to the ones obtained for light beams in\na medium with a gradually changing refractive index. In smooth junctions,\nenergetically forbidden regions emerge, which increase reflections and can\ngenerate pronounced interference patterns, for example, whispering gallery\nmodes. The investigated devices do not only demonstrate the feasibility of the\ngradient-index electron optics in graphene pn junctions, such as Luneburg and\nMaxwell lenses, but may have also technological applications, for example, as\nelectron beam splitters, focusers and waveguides. The semi-classical\ntrajectories offer an efficient tool to estimate the current flow paths in such\nnano-electronic devices.",
        "positive": "Thermal radiation in systems of many dipoles: Systems of many nanoparticles or volume-discretized bodies exhibit collective\nradiative properties that could be used for enhanced, guided, or tunable\nthermal radiation. These are commonly treated as assemblies of point dipoles\nwith interactions described by Maxwell's equations and thermal fluctuations\ncorrelated by the fluctuation-dissipation theorem. Here, we unify different\ntheoretical descriptions of these systems and provide a complete derivation of\nmany-dipole thermal radiation, showing that the correct use of the\nfluctuation-dissipation theorem depends on the definitions of fluctuating and\ninduced dipole moments. We formulate a method to calculate the diffusive\nradiative thermal conductivity of arbitrary collections of nanoparticles; this\nallows the comparison of thermal radiation to other heat transfer modes and\nacross different material systems. We calculate the radiative thermal\nconductivity of ordered and disordered arrays of SiC and SiO2 nanoparticles and\nshow that thermal radiation can significantly contribute to thermal transport\nin these systems. We validate our calculations by comparison to the exact\nsolution for a one-dimensional particle chain, and we demonstrate that the\ndipolar approximation significantly underpredicts the exact results at\nseparation distances less than the particle radius."
    },
    {
        "anchor": "Weak localization correction to the FS interface resistance: The classical resistance of a contact between a ferromagnet (F) and a\nsuperconductor (S) acquires an additional contact term as compared to the\ncontact between a ferromagnet and a normal metal. The necessity to match\nspin-polarized current in a ferromagnet to spin-less current in the\nsuperconductor results in the accumulation of non-equilibrium polarization near\nthe F/S interface. In the present work, we show that the weak localization\ncorrection to the classical diffusion coefficient, $\\delta D$, is dependent on\nthe degree of polarization, with majority spins more likely to be reflected\nfrom the interface than minority spins. Taking into account the change in the\nspin polarized particle distribution in the F wire arising from $\\delta D$, we\ncalculate the weak localization correction to the F/S contact resistance.",
        "positive": "Concepts of antiferromagnetic spintronics: Antiferromagnetic spintronics is an emerging research field whose focus is on\nthe electrical and optical control of the antiferromagnetic order parameter and\nits utility in information technology devices. An example of recently\ndiscovered new concepts is the N\\'{e}el spin-orbit torque which allows for the\nantiferromagnetic order parameter to be controlled by an electrical current in\ncommon microelectronic circuits. In this review we discuss the utility of\nantiferromagnets as active and supporting materials for spintronics, the\ninterplay of antiferromagnetic spintronics with other modern research fields in\ncondensed matter physics, and its utility in future \"More than Moore\"\ninformation technologies."
    },
    {
        "anchor": "Network model and four-terminal transport in minimally twisted bilayer\n  graphene: We construct a two-channel scattering model for the triangular network of\nvalley Hall states in interlayer-biased minimally twisted bilayer graphene from\nsymmetry arguments and investigate electronic transport in a four-terminal\nsetup. In the absence of forward scattering, a single phenomenological\nparameter tunes the network between a triplet of chiral zigzag modes and\npseudo-Landau levels. Moreover, the chiral zigzag modes give rise to robust\nAharonov-Bohm resonances in the longitudinal conductance in the presence of a\nperpendicular magnetic field or an in-plane electric field. Interestingly, we\nfind that when both a magnetic field and an in-plane electric field are\napplied, the resonances of different zigzag branches split depending on their\npropagation direction relative to the in-plane electric field. We further\ndemonstrate that while the Hall response vanishes in the chiral zigzag regime,\na finite Hall response is obtained without destroying the Aharonov-Bohm\nresonances in the longitudinal response, by weakly coupling different zigzag\nbranches, which also gives rise to Hofstadter physics at accessible magnetic\nfields.",
        "positive": "Hamiltonian reconstruction via ringdown dynamics: Many experimental techniques aim at determining the Hamiltonian of a given\nsystem. The Hamiltonian describes the system's evolution in the absence of\ndissipation, and is often central to control or interpret an experiment. Here,\nwe theoretically propose and experimentally demonstrate a method for\nHamiltonian reconstruction from measurements over a large area of phase space,\novercoming the main limitation of previous techniques. A crucial ingredient for\nour method is the presence of dissipation, which enables sampling of the\nHamiltonian through ringdown-type measurements. We apply the method to a\ndriven-dissipative system -- a parametric oscillator -- observed in a rotating\nframe, and reconstruct the (quasi-)Hamiltonian of the system. Furthermore, we\ndemonstrate that our method provides direct experimental access to the\nso-called symplectic norm of the stationary states of the system, which is tied\nto the particle- or hole-like nature of excitations of these states. In this\nway, we establish a method to unveil qualitative differences between the\nfluctuations around stabilized minima and maxima of the nonlinear\nout-of-equilibrium stationary states. Our method constitutes a versatile\napproach to characterize a wide class of driven-dissipative systems."
    },
    {
        "anchor": "Unveiling nontrivial fusion rule of Majorana zero mode using a fermionic\n  mode: Fusing Majorana zero modes leads to multiple outcomes, a property being\nunique to non-Abelian anyons. Successful demonstration of this nontrivial\nfusion rule would be a hallmark for the development of topological quantum\ncomputation.Here we show that this can be done by simply attaching a fermionic\nmode to a single Majorana zero mode. Through modulation of the energy level of\nthis fermionic mode as well as its coupling with the Majorana mode in different\nsequences, we show that a zero or integer charge pumping can be realized when\ndifferent fusion loops are chosen. Such fusion loops are intimately related\nwith the nontrivial fusion rule of Majorana modes and are solely determined by\nthe crossings at zero energy in the parameter space. Finally we demonstrate our\nproposal in a nanowire-based topological superconductor coupled to a quantum\ndot. We show that the charge pumping is robust for MZMs in the real system\nirrespective of the initial condition of FM state, contrary to the case for\ntrivial Andreev bound states. This provides a feasible way to distinguish\nMajorana modes from trivial Andreev bound states.",
        "positive": "Plasmon geometric phase and plasmon Hall shift: The collective plasmonic modes of a metal comprise a pattern of charge\ndensity and tightly-bound electric fields that oscillate in lock-step to yield\nenhanced light-matter interaction. Here we show that metals with non-zero Hall\nconductivity host plasmons with a fine internal structure: they are\ncharacterized by a current density configuration that sharply departs from that\nof ordinary zero Hall conductivity metals. This non-trivial internal structure\ndramatically enriches the dynamics of plasmon propagation, enabling plasmon\nwavepackets to acquire geometric phases as they scatter. Strikingly, at\nboundaries these phases accumulate allowing plasmon waves that reflect off to\nexperience a non-reciprocal parallel shift along the boundary displacing the\nincident and reflected plasmon trajectories. This plasmon Hall shift, tunable\nby Hall conductivity as well as plasmon wavelength, displays the chirality of\nthe plasmon's current distribution and can be probed by near-field photonics\ntechniques. Anomalous plasmon dynamics provide a real-space window into the\ninner structure of plasmon bands, as well as new means for directing plasmonic\nbeams."
    },
    {
        "anchor": "Spatial trends of non-collinear exchange coupling mediated by itinerant\n  carriers with different Fermi surfaces: We study the exchange coupling mediated by itinerant carriers with spin-orbit\ninteraction by both analytic and numeric approaches. The mediated exchange\ncoupling is non-collinear and its spatial trends depend on the Fermi surface\ntopology of the itinerant carriers. Taking Rashba interaction as an example,\nthe exchange coupling is similar to the conventional\nRuderman-Kittel-Kasuya-Yosida type in weak coupling. On the other hand, in the\nstrong coupling, the spiral interaction dominates. In addition, inclusion of\nfinite spin relaxation always makes the non-collinear spiral exchange\ninteraction dominant. Potential applications of our findings are explained and\ndiscussed.",
        "positive": "Topology of a dissipative spin: dynamical Chern number, bath induced\n  non-adiabaticity and a quantum dynamo effect: We analyze the topological deformations of a spin-1/2 in an effective\nmagnetic field induced by an ohmic quantum dissipative environment at zero\ntemperature. From Bethe Ansatz results and a variational approach, we confirm\nthat the Chern number is preserved in the delocalized phase for $\\alpha<1$. We\nreport a divergence of the Berry curvature at the equator when $\\alpha_c=1$\nthat appears at the localization Kosterlitz-Thouless quantum phase transition\nin this model. Recent experiments in quantum circuits have engineered\nnon-equilibrium protocols in time to access topological properties at\nequilibrium from the measure of the (quasi-)adiabatic out-of-equilibrium spin\nexpectation values. Applying a numerically exact stochastic Schr\\\"{o}dinger\nequation we find that, for a fixed sweep velocity, the bath induces a crossover\nfrom (quasi-)adiabatic to non-adiabatic dynamical behavior when the spin bath\ncoupling increases. We also investigate the particular regime $H/\\omega_c \\ll\nv/H \\ll 1$, where the dynamical Chern number observable built from\nout-of-equilibrium spin expectation values vanishes at $\\alpha=1/2$. In this\nregime, the mapping to an interacting resonance level model enables us to\ncharacterize the evolution of the dynamical Chern number in the vicinity of\n$\\alpha=1/2$. Then, we provide an intuitive physical explanation of the\nbreakdown of adiabaticity in analogy to the Faraday effect in electromagnetism.\nWe demonstrate that the driving of the spin leads to the production of a large\nnumber of bosonic excitations in the bath, which in return strongly affect the\nspin dynamics. Finally, we quantify the spin-bath entanglement and build an\nanalogy with an effective model at thermal equilibrium."
    },
    {
        "anchor": "Anomalous Entanglement in Chaotic Dirac Billiards: We present analytical and numerical results that demonstrate the presence of\nanomalous entanglement behavior on the Dirac Billiards. We investigate the\nstatistical distribution of the characteristic entangled measures, focusing on\nthe mean, on the variance and on the quantum interference terms. We show a\nquite distinct behavior of the Dirac Billiard compared with the non-relativist\n(Schrodinger) ones. Particularly, we show a very plausible Bell state and a\nsharp amplitude of quantum interference term on entangled electrons left from\nthe Dirac Billiards. The results have remarkable relevance to the novel quantum\ndots build of materials like graphene or topological insulators.",
        "positive": "Nonlinearities and Noise-Signal Relations in Electronic Heat Transport\n  via Molecules: We examine the electronic heat transport phenomena in nanoscale junctions\ncomposed of organic molecules coupled to two metallic reservoirs of different\ntemperatures. The electronic heat flux and its dynamical noise properties are\ncalculated within the scattering (Landauer) formalism with the transmission\nprobability determined by using non-equilibrium Green's functions (NEGF\ntechnique). The method based on Taylor series expansion is used to determine\nnonlinear corrections to the electronic heat flux and its noise power spectral\ndensity with up to the second order terms with respect to the temperature\ndifference. Our results show only limited applicability of ballistic Fourier's\nlaw and fluctuation-dissipation theorem to heat transport in molecular systems.\nWe derived and tested numerically several signal-signal, noise-signal, and\nnoise-noise relations applicable to nanoscale heat flow carried by electrons at\nstrongly non-equilibrium conditions (similar formulas are expected for phonons\nand photons). Importantly, the special treatment proposed by us may be extended\nto higher order terms in order to address a variety of problems related to\nnonlinear thermal and electro-thermal effects which may occur at nanoscale."
    },
    {
        "anchor": "Topolectric circuits: Theory and construction: We highlight a general theory to engineer arbitrary Hermitian tight-binding\nlattice models in electrical LC circuits, where the lattice sites are replaced\nby the electrical nodes, connected to its neighbors and to the ground by\ncapacitors and inductors. In particular, by supplementing each node with $n$\nsubnodes, where the phases of the current and voltage are the $n$ distinct\nroots of \\emph{unity}, one can in principle realize arbitrary hopping amplitude\nbetween the sites or nodes via the \\emph{shift capacitor coupling} between\nthem. This general principle is then implemented to construct a plethora of\ntopological models in electrical circuits, \\emph{topolectric circuits}, where\nthe robust zero-energy topological boundary modes manifest through a large\nboundary impedance, when the circuit is tuned to the resonance frequency. The\nsimplicity of our circuit constructions is based on the fact that the existence\nof the boundary modes relies only on the Clifford algebra of the corresponding\nHermitian matrices entering the Hamiltonian and not on their particular\nrepresentation. This in turn enables us to implement a wide class of\ntopological models through rather simple topolectric circuits with nodes\nconsisting of only two subnodes. We anchor these outcomes from the numerical\ncomputation of the on-resonance impedance in circuit realizations of\nfirst-order ($m=1$), such as Chern and quantum spin Hall insulators, and\nsecond- ($m=2$) and third- ($m=3$) order topological insulators in different\ndimensions, featuring sharp localization on boundaries of codimensionality\n$d_c=m$. Finally, we subscribe to the \\emph{stacked topolectric circuit}\nconstruction to engineer three-dimensional Weyl, nodal-loop, quadrupolar Dirac\nand Weyl semimetals, respectively displaying surface and hinge localized\nimpedance.",
        "positive": "Inelastic carrier lifetime in graphene: We consider hot carrier inelastic scattering due to electron--electron\ninteractions in graphene, as functions of carrier energy and density. We\ncalculate the imaginary part of the zero-temperature quasiparticle self-energy\nfor doped graphene, utlizing the $G_0W$ and random phases approximations. Using\nthe full dynamically screened Coulomb interaction, we obtain the inelastic\nquasiparticle lifetimes and associated mean free paths. The linear dispersion\nof graphene gives lifetime energy dependences that are qualitatively different\nfrom those of parabolic-band semiconductors. We also get good agreement with\ndata from angle-resolved photoemission spectroscopy experiments."
    },
    {
        "anchor": "Multibit memory operation of metal-oxide bi-layer memristors: In this work, we evaluate a multitude of metal-oxide bi-layers and\ndemonstrate the benefits from increased memory stability via multibit memory\noperation. We introduce a programming methodology that allows for operating\nmetal-oxide memristive devices as multibit memory elements with highly packed\nyet clearly discernible memory states. We finally demonstrate a 5.5-bit memory\ncell (47 resistive states) with excellent retention and power consumption\nperformance. This paves the way for neuromorphic and non-volatile memory\napplications.",
        "positive": "Spectroscopy of Valley Splitting in a Silicon/Silicon-Germanium\n  Two-Dimensional Electron Gas: The lifting of the two-fold degeneracy of the conduction valleys in a\nstrained silicon quantum well is critical for spin quantum computing. Here, we\nobtain an accurate measurement of the splitting of the valley states in the\nlow-field region of interest, using the microwave spectroscopy technique of\nelectron valley resonance (EVR). We compare our results with conventional\nmethods, observing a linear magnetic field dependence of the valley splitting,\nand a strong low-field suppression, consistent with recent theory. The\nresonance linewidth shows a marked enhancement above $T\\simeq 300$ mK."
    },
    {
        "anchor": "Fock Space formulation for Nanoscale transport: In this paper we present a general formulation for electronic transport that\ncombines strong correlation effects with broadening and quantum coherence, and\nillustrate it with a simple example (\"spin blockade\") that clearly demonstrates\nall three effects. The standard master equation method for Coulomb blockade\ncaptures the first effect, while a number of different approaches such as the\nnon-equilibrium Green function (NEGF) method are available for handling the\nlast two. But there is a need for a method that captures all three and in this\npaper we propose an approach that appears to fulfill this need. The equations\nlook similar to the NEGF formalism but one basic distinction is that all\nquantities (like the Hamiltonian) appearing in our formalism are defined in\nFock space and as such are matrices of dimension (2^N by 2^N), N being the\nnumber of basis functions describing the one-electron Hilbert space. Similar\nquantities appearing in the NEGF formalism are of dimension (N by N). Other\nimportant differences arise from the fact that in Fock space there is no need\nto include the exclusion principle explicitly and that elastic processes in\none-electron space look like inelastic processes in Fock space. A simple\nnumerical example is presented to show that our approach includes strong\nelectron-electron interaction, broadening due to coupling to contacts and\nquantum coherence effects due to spin polarization in directions other than the\nz-direction. The basic equations for this \"Fock space Green's function\" (FSGF)\nare quite general and should be applicable to more interesting and exotic\ntransport problems involving the entanglement of many-electron states. How\neffective it will be remains to be assessed for different problems, but our\npreliminary results for the Kondo peak look encouraging.",
        "positive": "Greatly enhanced light emission of MoS$_{2}$ using photonic crystal\n  heterojunction: We study the effect of one-dimensional (1D) photonic crystal heterojunction\n(h-PhC) on the light absorption and light emission of monolayer molybdenum\ndisulfide (MoS$_{2}$), and obtained the analytical solution of the light\nabsorption and emission of two-dimensional materials in 1D h-PhC.\nSimultaneously enhancing the light absorption and emission of the medium in\nmultiple frequency ranges is easy as h-PhC has more models of photon\nlocalization than the common photonic crystal. Result shows that h-PhC can\nsimultaneously enhance the light absorption and emission of MoS$_{2}$ and\nenhance the photoluminescence spectrum of MoS$_{2}$ by 2-3 orders of magnitude."
    },
    {
        "anchor": "Multiple Andreev Reflection and Giant Excess Noise in Diffusive\n  Superconductor/Normal-Metal/Superconductor Junctions: We have studied superconductor/normal metal/superconductor (SNS) junctions\nconsisting of short Au or Cu wires between Nb or Al banks. The Nb based\njunctions display inherent electron heating effects induced by the high thermal\nresistance of the NS boundaries. The Al based junctions show in addition\nsubharmonic gap structures in the differential conductance dI/dV and a\npronounced peak in the excess noise at very low voltages V. We suggest that the\nnoise peak is caused by fluctuations of the supercurrent at the onset of\nJosephson coupling between the superconducting banks. At intermediate\ntemperatures where the supercurrent is suppressed a noise contribution ~1/V\nremains, which may be interpreted as shot noise originating from large multiple\ncharges.",
        "positive": "Graphene-mediated interaction between adsorbed impurities: Interaction between adsorbed atoms in graphene is studied using a combination\nof DFT and the path integral formalism. Our results reveal a complex\nnon-monotonic interaction profile. We show that the strength and sign of the\ninteraction are dictated by the arrangement of impurities, as well as the\nsystem doping. These findings can be used to interpret the complex behavior of\nimpurities in experimentally realized systems, as well as other classes of\nimpurities, such as C substitutions in graphene."
    },
    {
        "anchor": "Spin and interaction effects in quantum dots: a Hartree-Fock-Koopmans\n  approach: We use a Hartree-Fock-Koopmans approach to study spin and interaction effects\nin a diffusive or chaotic quantum dot. In particular, we derive the statistics\nof the spacings between successive Coulomb-blockade peaks. We include\nfluctuations of the matrix elements of the two-body screened interaction,\nsurface-charge potential, and confining potential to leading order in the\ninverse Thouless conductance. The calculated peak-spacing distribution is\ncompared with experimental results.",
        "positive": "Real-space Obstruction in Quantum Spin Hall Insulators: The recently introduced classification of two-dimensional insulators in terms\nof topological crystalline invariants has been applied so far to \"obstructed\"\natomic insulators characterized by a mismatch between the centers of the\nelectronic Wannier functions and the ionic positions. We extend this notion to\nquantum spin Hall insulators in which the ground state cannot be described in\nterms of time-reversal symmetric localized Wannier functions. A system\nequivalent to graphene in all its relevant electronic and topological\nproperties except for a real-space obstruction is identified and studied via\nsymmetry analysis as well as with density functional theory. The low-energy\nmodel comprises a local spin-orbit coupling and a non-local symmetry breaking\npotential, which turn out to be the essential ingredients for an obstructed\nquantum spin Hall insulator. An experimental fingerprint of the obstruction is\nthen measured in a large-gap triangular quantum spin Hall material."
    },
    {
        "anchor": "Quantum-dot-like states in molybdenum disulfide nanostructures due to\n  the interplay of local surface wrinkling, strain, and dielectric confinement: The observation of quantum light emission from atomically thin transition\nmetal dichalcogenides has opened a new field of applications for these material\nsystems. The corresponding excited charge-carrier localization has been linked\nto defects and strain, while open questions remain regarding the microscopic\norigin. We demonstrate that the bending rigidity of these materials leads to\nwrinkling of the two-dimensional layer. The resulting strain field facilitates\nstrong carrier localization due to its pronounced influence on the band gap.\nAdditionally, we consider charge carrier confinement due to local changes of\nthe dielectric environment and show that both effects contribute to modified\nelectronic states and optical properties. The interplay of surface wrinkling,\nstrain-induced confinement, and local changes of the dielectric environment is\ndemonstrated for the example of nanobubbles that form when monolayers are\ndeposited on substrates or other two-dimensional materials.",
        "positive": "Andreev Tunneling in Strongly Interacting Quantum Dots: We review recent work on resonant Andreev tunneling through a strongly\ninteracting quantum dot connected to a normal and to a superconducting lead. We\nderive a general expression for the current flowing in the structure and\ndiscuss the linear and non-linear transport in the nonperturbative regime. New\neffects associated to the Kondo resonance combined with the two-particle\ntunneling arise. The Kondo anomaly in the $I-V$ characteristics depends on the\nrelative size of the gap energy and the Kondo temperature."
    },
    {
        "anchor": "Coherent Destruction of Coulomb Blockade Peaks in Molecular Junctions: Coherent electronic transport in single-molecule junctions is investigated in\nthe Coulomb blockade regime. Both the transmission phase and probability are\ncalculated for junctions with various contact symmetries. A dramatic\nsuppression of the Coulomb blockade peaks is predicted for junctions where\nmultiple atomic orbitals of the molecule couple to a single electrode although\nthe charging steps are unaffected.",
        "positive": "Large shift current via in-gap and charge-neutral exciton excitations in\n  BN nanotubes and single BN layer: We perform {\\it ab initio} many-body calculations to investigate the exciton\nshift current in small diameter zigzag BN nanotubes and also single BN sheet,\nusing the GW plus Bethe-Salpeter equation (GW-BSE) method with the newly\ndeveloped efficient algorithms. Our GW-BSE calculations reveal a giant in-gap\npeak in the shift current spectrum in all the studied BN systems due to the\nexcitation of the A exciton. The peak value of the excitonic shift current is\nmore than three times larger than that of the quasiparticle shift current, and\nis attributed to the gigantic enhancement of the optical dipole matrix element\nby the A exciton resonance. The effective exciton shift current conductivity is\nnearly ten times larger than the largest shift conductivity observed in\nferroelectric semiconductors. Importantly, the direction of the shift current\nin the BN nanotubes is found to be independent of the tube chirality ($n,0$)\n(or diameter), contrary to the simple rule of $\nsgn(J_\\text{shift})=\\text{mod}(n,3)$ predicted by previous model Hamiltonian\nstudies. Finally, our {\\it ab initio} calculations also show that the exciton\nexcitation energies decrease significantly with the decreasing diameter due to\nthe curvature-induced orbital rehybridization in small diameter zigzag BN\nnanotubes."
    },
    {
        "anchor": "Phase coherent transport and spin-orbit interaction in GaAs/InSb\n  core/shell nanowires: Low-temperature magnetotransport measurements are performed on GaAs/InSb\ncore-shell nanowires. The nanowires were self-catalyzed grown by molecular beam\nepitaxy. The conductance measurements as a function of back-gate voltage show\nan ambipolar behavior comprising an insulating range in between the transition\nfrom the p-type to the n-type region. Simulations based on a self-consistent\nSchr\\\"odinger--Poisson solver revealed that the ambipolar characteristics\noriginate from a Fermi level dependent occupation of hole and electron states\nwithin the approximately circular quantum well formed in the InSb shell. By\napplying a perpendicular magnetic field with respect to the nanowire axis,\nconductance fluctuations were observed, which are used to extract the\nphase-coherence length. By averaging the magneto-conductance traces at\ndifferent back-gate voltages, weak antilocalization features are resolved.\nRegular flux-periodic conductance oscillations are measured when an axial\nmagnetic field is applied. These oscillations are attributed to closed-loop\nquantized states located in the InSb shell which shift their energetic position\nperiodically with the magnetic flux. Possible reasons for experimentally\nobserved variations in the oscillation patterns are discussed using simulation\nresults.",
        "positive": "Transport through a monolayer-tube junction: sheet-to-tube spin current\n  in silicene: A method is developed to calculate the electron flow between an atomic\nmonolayer sheet and a tube with use of tunneling matrix elements between\nmonolayer sheets and applied to the spin current from monolayer silicene with\nsublattice-staggered current-induced spin polarization to silicene tube.\nCalculated sheet-to-tube spin current exhibits an oscillation as a function of\nthe tube circumferential length since the Fermi points in the tube cross the\nFermi circle in the sheet. It is also shown that the spin current with spin in\nthe out-of-plane direction, which is absent in the sheet-sheet junction\n(including twisted sheets) with the $C_3$ rotational symmetry, appears in an\noscillating form owing to the broken $C_3$ symmetry in the tube-sheet junction."
    },
    {
        "anchor": "Interplay of Rashba spin orbit coupling and disorder in the conductance\n  properties of a four terminal junction device: We report a thorough theoretical investigation on the quantum transport of a\ndisordered four terminal device in the presence of Rashba spin orbit coupling\n(RSOC) in two dimensions. Specifically we compute the behaviour of the\nlongitudinal (charge) conductance, spin Hall conductance and spin Hall\nconductance fluctuation as a function of the strength of disorder and Rashba\nspin orbit interaction using the Landauer Buttiker formalism via Green's\nfunction technique. Our numerical calculations reveal that both the\nconductances diminish with disorder. At smaller values of the RSOC parameter,\nthe longitudinal and spin Hall conductances increase, while both vanish in the\nstrong RSOC limit. The spin current is more drastically affected by both\ndisorder and RSOC than its charge counterpart. The spin Hall conductance\nfluctuation does not show any universality in terms of its value and it depends\non both disorder as well as on the RSOC strength. Thus the spin Hall\nconductance fluctuation has a distinct character compared to the fluctuation in\nthe longitudinal conductance. Further one parameter scaling theory is studied\nto assess the transition to a metallic regime as claimed in literature and we\nfind no confirmation about the emergence of a metallic state induced by RSOC.",
        "positive": "Kinetic theory of surface plasmon polariton in semiconductor nanowires: Based on the semiclassical model Hamiltonian of the surface plasmon polariton\nand the nonequilibrium Green-function approach, we present a microscopic\nkinetic theory to study the influence of the electron scattering on the\ndynamics of the surface plasmon polariton in semiconductor nanowires. The\ndamping of the surface plasmon polariton originates from the resonant\nabsorption by the electrons (Landau damping), and the corresponding damping\nexhibits size-dependent oscillations and distinct temperature dependence\nwithout any scattering. The scattering influences the damping by introducing a\nbroadening and a shifting to the resonance. To demonstrate this, we investigate\nthe damping of the surface plasmon polariton in InAs nanowires in the presence\nof the electron-impurity, electron-phonon and electron-electron Coulomb\nscatterings. The main effect of the electron-impurity and electron-phonon\nscatterings is to introduce a broadening, whereas the electron-electron Coulomb\nscattering can not only cause a broadening, but also introduce a shifting to\nthe resonance. For InAs nanowires under investigation, the broadening due to\nthe electron-phonon scattering dominates. As a result, the scattering has a\npronounced influence on the damping of the surface plasmon polariton: The\nsize-dependent oscillations are smeared out and the temperature dependence is\nalso suppressed in the presence of the scattering. These results demonstrate\nthe the important role of the scattering on the surface plasmon polariton\ndamping in semiconductor nanowires."
    },
    {
        "anchor": "Simulation of light propagation in thin semiconductor films with\n  non-local electron-photon interaction: The propagation of light in layered semiconductor media is described\ntheoretically and simulated numerically within the framework of the\nnon-equilibrium Green's function formalism as used for state-of-the-art\nnanodevice simulations, treating the non-local interaction of leaky photonic\nmodes with the electronic states of thin semiconductor films on a\nnon-equilibrium quantum statistical mechanics level of theory. For a diagonal\nphoton self-energy corresponding to local coupling, the simulation results for\na 500 nm GaAs slab under normal incidence are in excellent agreement with the\npredictions from the conventional transfer matrix method. The deviations of the\nlocal approximation from the result provided by the fully non-local photon\nself-energy for a 100 nm GaAs film are found to be small.",
        "positive": "Two-spin dephasing by electron-phonon interaction in semiconductor\n  double quantum dots: We study electron-phonon interaction induced decoherence between two-electron\nsinglet and triplet states in a semiconductor double quantum dot using a\nspin-boson model. We investigate the onset and time evolution of this\ndephasing, and study its dependence on quantum dot parameters such as dot size\nand double dot separations, as well as the host materials (GaAs and Si). At the\nshort time limit, electron-phonon interaction only causes an incomplete initial\nGaussian decay of the off-diagonal density matrix element in the\nsinglet-triplet Hilbert space. A complete long-time exponential decay due to\nphonon relaxation would eventually dominate over two-spin decoherence. We\nanalyze two-spin decoherence in both symmetric and biased double quantum dots,\nidentifying their difference in electron-phonon coupling and the relevant\nconsequences."
    },
    {
        "anchor": "Graphene Andreev Billiards: We studied the energy levels of graphene based Andreev billiards consisting\nof a superconductor region on top of a monolayer graphene sheet. For the case\nof Andreev retro-reflection we show that the graphene based Andreev billiard\ncan be mapped to the normal metal-superconducting billiards with the same\ngeometry. We also derived a semiclassical quantization rule in graphene based\nAndreev billiards. The exact and the semiclassically obtained spectrum agree\nvery well both for the case of Andreev retro-reflection and specular Andreev\nreflection.",
        "positive": "Reveal the non-local coherent nature from a dissipative Majorana\n  teleportation: The non-local coherent nature of the Majorana devices is one of the key\nfactors for realizing decoherence-free topological qubits. Direct observation\nof this coherent nature could provide a first-step benchmarking scheme to\nvalidate Majorana qubit quality. We propose a simple transport scheme with a\nMajorana island device along with a dissipative environment in the electrodes.\nWe found that the dissipative environment renormalizes the quantum transport in\nsignificant different ways: As reducing temperature, while the conductance for\nMajorana coherent teleportation increases, all other incoherent signals are\nstrongly suppressed due to dissipation. This special conductance scaling\nbehavior is a clear benchmark to reveal the non-local coherent nature of\nMajorana devices."
    },
    {
        "anchor": "Finite-size effects in non-Hermitian topological systems: We systematically investigate the finite-size effects in non-Hermitian\none-dimensional (1D) Su-Schrieffer-Heeger (SSH) and two-dimensional (2D) Chern\ninsulator models. Using a combination of analytical and numerical calculations,\nwe show that the non-Hermitian intra-cell hoppings in the SSH model can modify\nthe localization lengths of bulk and end states, giving rise to a complex\nfinite-size energy gap that exhibits an oscillating exponential decay as the\nchain length grows. However, the imaginary staggered on-site potentials in the\nSSH model only change the end-state energy, leaving the localization lengths of\nthe system unchanged. In this case, the finite-size energy gap can undergo a\ntransition from real values to imaginary values. We observed similar phenomena\nfor the finite-size effect in 2D Chern insulator systems.",
        "positive": "Sub-cycle optical control of current in a semiconductor: from the\n  multiphoton to the tunneling regime: Nonlinear interactions between ultrashort optical waveforms and solids can be\nused to induce and steer electric current on a femtosecond (fs) timescale,\nholding promise for electronic signal processing at PHz frequencies [Nature\n493, 70 (2013)]. So far, this approach has been limited to insulators,\nrequiring extremely strong peak electric fields and intensities. Here, we show\nall-optical generation and control of directly measurable electric current in a\nsemiconductor relevant for high-speed and high-power (opto)electronics, gallium\nnitride (GaN), within an optical cycle and on a timescale shorter than 2 fs, at\nintensities at least an order of magnitude lower than those required for\ndielectrics. Our approach opens the door to PHz electronics and metrology,\napplicable to low-power (non-amplified) laser pulses, and may lead to future\napplications in semiconductor and photonic integrated circuit technologies."
    },
    {
        "anchor": "Line-Node Dirac Semimetal and Topological Insulating Phase in\n  Noncentrosymmetric Pnictides CaAgX (X = P, As): Two noncentrosymmetric ternary pnictides, CaAgP and CaAgAs, are reported as\ntopological line-node semimetals protected solely by mirror-reflection\nsymmetry. The band gap vanishes on a circle in momentum space, and surface\nstates emerge within the circle. Extending this study to spin-orbit coupled\nsystems reveals that, compared with CaAgP, a substantial band gap is induced in\nCaAgAs by large spin-orbit interaction. The resulting states are a topological\ninsulator, in which the Z2 topological invariant is given by 1; 000. To clarify\nthe Z2 topological invariants for time-reversal-invariant systems without\nspatial-inversion symmetry, we introduce an alternative way to calculate the\ninvariants characterizing a line node and topological insulator for\nmirror-reflection-invariant systems.",
        "positive": "Collapse of $\u03c1_{xx}$ ringlike structures in 2DEGs under tilted\n  magnetic fields: In the quantum Hall regime, the longitudinal resistivity $\\rho_{xx}$ plotted\nas a density--magnetic-field ($n_{2D}-B$) diagram displays ringlike structures\ndue to the crossings of two sets of spin split Landau levels from different\nsubbands [e.g., Zhang \\textit{et al.}, Phys. Rev. Lett. \\textbf{95}, 216801\n(2005)]. For tilted magnetic fields, some of these ringlike structures \"shrink\"\nas the tilt angle is increased and fully collapse at $\\theta_c \\approx\n6^\\circ$. Here we theoretically investigate the topology of these structures\nvia a non-interacting model for the 2DEG. We account for the inter Landau-level\ncoupling induced by the tilted magnetic field via perturbation theory. This\ncoupling results in anti-crossings of Landau levels with parallel spins. With\nthe new energy spectrum, we calculate the corresponding $n_{2D}-B$ diagram of\nthe density of states (DOS) near the Fermi level. We argue that the DOS\ndisplays the same topology as $\\rho_{xx}$ in the $n_{2D}-B$ diagram. For the\nring with filling factor $\\nu=4$, we find that the anti-crossings make it\nshrink for increasing tilt angles and collapse at a large enough angle. Using\neffective parameters to fit the $\\theta = 0^\\circ$ data, we find a collapsing\nangle $\\theta_c \\approx 3.6^\\circ$. Despite this factor-of-two discrepancy with\nthe experimental data, our model captures the essential mechanism underlying\nthe ring collapse."
    },
    {
        "anchor": "Unusual ultralow frequency fluctuations in freestanding graphene: Intrinsic ripples in freestanding graphene have been exceedingly difficult to\nstudy. Individual ripple geometry was recently imaged using scanning tunneling\nmicroscopy, but these measurements are limited to static configurations.\nThermally-activated flexural phonon modes should generate dynamic changes in\ncurvature. Here we show how to track the vertical movement of a\none-square-angstrom region of freestanding graphene using scanning tunneling\nmicroscopy, thereby allowing measurement of the out-of-plane time trajectory\nand fluctuations over long time periods. We also present a model from\nelasticity theory to explain the very-low-frequency oscillations. Unexpectedly,\nwe sometimes detect a sudden colossal jump, which we interpret as due to mirror\nbuckling. This innovative technique provides a much needed atomic-scale probe\nfor the time-dependent behavior of intrinsic ripples. The discovery of this\nnovel progenitor represents a fundamental advance in the use of scanning\ntunneling microscopy, which together with the application of a thermal load\nprovides a low-frequency nano-resonator.",
        "positive": "Emergent topological phenomena in thin films of pyrochlore iridates: Two quintessential ingredients governing the topological invariant of a\nsystem are the dimensionality and the symmetry of the system. Due to the recent\ndevelopment of thin film and artificial superstructure growth technique, it is\npossible to control the dimensionality of the system, smoothly between the\ntwo-dimensions (2D) and three-dimensions (3D). In this work we unveil the\ndimensional crossover of emergent topological phenomena in correlated\ntopological materials. In particular, by focusing on the thin film of\npyrochlore iridate antiferromagnets grown along the [111] direction, we\ndemonstrate that it can show giant anomalous Hall conductance, which is\nproportional to the thickness of the film, even though there is no Hall effect\nin 3D bulk material. In addition, we uncover the emergence of a new topological\nphase, whose nontrivial topological properties are hidden in the bulk insulator\nbut manifest only in thin films. This shows that the thin film of topological\nmaterials is a new platform to search for unexplored novel topological\nphenomena."
    },
    {
        "anchor": "Impurity induced current in a Chern insulator: Chern insulators arguably provide the simplest examples of topological\nphases. They are characterized by a topological invariant and can be identified\nby the presence of protected edge states. In this article, we show that a local\nimpurity in a Chern insulator induces a twofold response: bound states that\ncarry a chiral current and a net current circulating around the impurity. This\nis a manifestation of broken time symmetry and persists even for an\ninfinitesimal impurity potential. To illustrate this, we consider a Coulomb\nimpurity in the Haldane model. Working in the low-energy long-wavelength limit,\nwe show that an infinitesimal impurity strength suffices to create bound\nstates. We find analytic wavefunctions for the bound states and show that they\ncarry a circulating current. In contrast, in the case of a trivial analogue,\ngraphene with a gap induced by a sublattice potential, bound states occur but\ncarry no current. In the many body problem of the Haldane model at\nhalf-filling, we use a linear response approach to demonstrate a circulating\ncurrent around the impurity. Impurity textures in insulators are generally\nexpected to decay exponentially; in contrast, this current decays polynomially\nwith distance from the impurity. Going beyond the Haldane model, we consider\nthe case of coexisting trivial and non-trivial masses. We find that the\nimpurity induces a local chiral current as long as time reversal symmetry is\nbroken. However, the decay of this local current bears a signature of the\noverall topology - the current decays polynomially in a non-trivial system and\nexponentially in a trivial system. In all cases, our analytic results agree\nwell with numerical tight-binding simulations.",
        "positive": "The Effective field theory of 2+1 dimensional topological insulator in\n  the presence of Rashba spin-orbit interaction: 2+1 dimensional topological insulator described by the Kane-Mele model in the\npresence of Rashba spin-orbit interaction is considered. The effective action\nof the external fields coupled to electromagnetic and spin degrees of freedom\nis accomplished within this model. The Hamiltonian methods are adopted to\nprovide the coefficients appearing in the action. It is demonstrated\nstraightforwardly that the coefficients of the Chern-Simons terms are given by\nthe first Chern number attained through the related non-Abelian Berry gauge\nfield. The effective theory which we obtain is in accord with the existence of\nthe spin Hall phase where the value of the spin Hall conductivity is very close\nto the quantized one."
    },
    {
        "anchor": "Random-matrix modeling of semi-linear response, the generalized variable\n  range hopping picture, and the conductance of mesoscopic rings: Semi-linear response theory determines the absorption coefficient of a driven\nsystem using a resistor network calculation: Each unperturbed energy level of a\nparticle in a vibrating trap, or of an electron in a mesoscopic ring, is\nregarded as a node ($n$) of the network; The transition rates ($w_{mn}$)\nbetween the nodes are regarded as the elements of a random matrix that\ndescribes the network. If the size-distribution of the connecting elements is\nwide (e.g. log-normal-like rather than Gaussian-like) the result for the\nabsorption coefficient differs enormously from the conventional Kubo prediction\nof linear response theory. We use a generalized variable range hopping scheme\nfor the analysis. In particular we apply this approach to obtain practical\napproximations for the conductance of mesoscopic rings. In this context Mott's\npicture of diffusion and localization is revisited.",
        "positive": "Spin-dependent electronic lenses based on hybrid graphene nanostructures: We study electronic transport in graphene/ferromagnetic insulator hybrid\ndevices. The system comprises an armchair graphene nanoribbon with a\nlens-shaped EuO ferromagnetic insulator layer deposited on top of it. When the\ndevice supports a large number of propagating modes, the proximity exchange\ninteraction of electrons with the magnetic ions of the ferromagnetic insulator\nresults in electrons being spatially localised at different spots depending on\ntheir spin. We found the spin-dependent electron focusing is robust under\nmoderate edge disorder. A spin-polarised electric current can be generated by\nplacing a third contact in the proper place. This opens the possibility to use\nthese effects for fabricating tunable sources of polarized electrons."
    },
    {
        "anchor": "Classical and Quantum Plasmonics in Graphene Nanodisks: the Role of Edge\n  States: Edge states are ubiquitous for many condensed matter systems with\nmulticomponent wave functions. For example, edge states play a crucial role in\ntransport in zigzag graphene nanoribbons. Here, we report microscopic\ncalculations of quantum plasmonics in doped graphene nanodisks with zigzag\nedges. We express the nanodisk conductivity $\\sigma(\\omega)$ as a sum of the\nconventional bulk conductivity $\\sigma_{\\scriptscriptstyle\\text{B}}(\\omega)$,\nand a novel term $\\sigma_{\\scriptscriptstyle\\text{E}}(\\omega)$, corresponding\nto a coupling between the edge and bulk states. We show that the edge states\ngive rise to a red-shift and broadening of the plasmon resonance, and that they\noften significantly impact the absorption efficiency. We further develop\nsimplified models, incorporating nonlocal response within a hydrodynamical\napproach, which allow a semiquantitative description of plasmonics in the\nultrasmall size regime. However, the polarization dependence is only given by\nfully microscopic models. The approach developed here should have many\napplications in other systems supporting edge states.",
        "positive": "Strong coupling between a metallic nanoparticle and a single molecule: We theoretically investigate strong coupling between a single molecule and a\nsingle metallic nanoparticle. A theory suited for the quantum-mechanical\ndescription of surface plasmon polaritons (SPPs) is developed. The coupling\nbetween these SPPs and a single molecule, and the modified molecular dynamics\nin presence of the nanoparticle are described within a combined Drude and\nboundary-element-method approach. Our results show that strong coupling is\npossible for single molecules and metallic nanoparticles, and can be observed\nin fluorescence spectroscopy through the splitting of emission peaks."
    },
    {
        "anchor": "Anomalous Hall effect, magneto-optical properties, and nonlinear optical\n  properties of twisted graphene systems: We study the anomalous Hall effect, magneto-optical properties, and nonlinear\noptical properties of twisted bilayer graphene (TBG) aligned with hexagonal\nboron nitride (hBN) substrate as well as twisted double bilayer graphene\nsystems. We show that non-vanishing valley polarizations in twisted graphene\nsystems would give rise to anomalous Hall effect which can be tuned by in-plane\nmagnetic fields. The valley polarized states are also associated with giant\nFaraday/Kerr rotations in the terahertz frequency regime. Moreover, both\nhBN-aligned TBG and TDBG exhibit colossal nonlinear optical responses by virtue\nof the inversion-symmetry breaking, the small bandwidth, and the small\nexcitation gaps of the systems. Our calculations indicate that in both systems\nthe nonlinear optical conductivities of the shift currents are on the order of\n$10^3\\,\\mu$A/V$^2$; and the second harmonic generation (SHG) susceptibilities\nare on the order of $10^6\\,$pm/V in the terahertz frequency regime. Moreover,\nin TDBG with $AB\\textrm{-}BA$ stacking, we find that a finite orbital\nmagnetization would generate a new component $\\sigma^{x}_{xx} $ of the\nnonlinear photoconductivity tensor; while in $AB$-$AB$ stacked TDBG with\nvertical electric fields, the valley polarization and orbital magnetization\nwould make significant contributions to the $\\sigma^{y}_{xx}$ component of the\nphotoconductivity tensor. These nonlinear photo-conductivities are proportional\nto the orbital magnetizations of the systems, thus they are expected to exhibit\nhysteresis behavior in response to out-of-plane magnetic fields.",
        "positive": "Unconventional magnetisation texture in graphene / cobalt hybrids: Magnetic domain structure and spin-dependent reflectivity measurements on\ncobalt thin films intercalated at the graphene / Ir(111) interface are\ninvestigated using spin-polarised low-energy electron microscopy. We find that\ngraphene-covered cobalt films have surprising magnetic properties. Vectorial\nimaging of magnetic domains reveals an unusually gradual thickness-dependent\nspin reorientation transition, in which magnetisation rotates from\nout-of-the-film plane to the in-plane direction by less than 10$^\\circ$ per\ncobalt monolayer. During this transition, cobalt films have a meandering spin\ntexture, characterised by a complex, three-dimensional, wavy magnetisation\npattern. In addition, spectroscopy measurements indicate that the electronic\nband structure of the unoccupied states is essentially spin-independent already\na few electron-Volts above the vacuum level. These properties strikingly differ\nfrom those of pristine cobalt films and could open new prospects in surface\nmagnetism."
    },
    {
        "anchor": "Non-uniform heat redistribution among multiple channels in the integer\n  quantum Hall regime: Heat transport in multiple quantum-Hall edge channels at Landau-level filling\nfactor nu = 2, 4, and 8 is investigated with a quantum point contact as a heat\ngenerator and a quantum dot as a local thermometer. Heat distribution among the\nchannels remains highly non-uniform, which can be understood with the plasmon\neigenmodes of the multiple channels. The heat transport can be controlled with\nanother quantum point contact as a quantized heat valve, as manifested by\nstepwise increases of heat current at the thermometer. This encourages\ndeveloping integrated heat circuits with quantum-Hall edge channels.",
        "positive": "Dissipative diamagnetism with anomalous coupling and third law: In this work, low temperature thermodynamic behaviour in the context of\ndissipative diamagnetism with anomalous coupling is analyzed. We find that\nfinite dissipation substitutes the zero-coupling result of exponential decay of\nentropy by a power law behaviour at low temperature. For Ohmic bath, entropy\nvanishes linearly with temperature, $T$, in conformity with Nernst's theorem.\nIt is also shown that entropy decays faster in the presence of anomalous\ncoupling than that of the usual coordinate-coordinate coupling. It is observed\nthat velocity-velocity coupling is the most advantageous coupling scheme to\nensure the third law of thermodynamics. It is also revealed that different\nthermodynamic functions are independent of magnetic field at very low\ntemperature for various coupling schemes discussed in this work."
    },
    {
        "anchor": "Two-dimensional negative donors in magnetic fields: A finite-difference solution of the Schroedinger equation for negative donor\ncenters D^- in two dimensions is presented. Our approach is of exact nature and\nallows us to resolve a discrepancy in the literature on the ground state of a\nnegative donor. Detailed calculations of the energies for a number of states\nshow that for field strengths less than \\gamma=0.117 a.u. the donor possesses\none bound state, for 0.117<\\gamma<1.68 a.u. there exist two bound states and\nfor field strengths \\gamma>1.68 a.u. the system possesses three bound states.\nFurther relevant characteristics of negative donors in magnetic fields are\nprovided.",
        "positive": "Free electron nanolaser based on the graphene plasmons: In this paper, a possible way to achieve lasing from THz to extreme UV domain\ndue to stimulated scattering of graphene plasmons on the free electrons is\nconsidered. The analytical-quantitative description of the proposed FEL scheme\nis based on the self-consistent set of the Maxwell--Vlasov equations. We study\nthe downconversion as well as the upconversion. It is shown that the coherent\ndownconversion of infrared radiation to THz one can be achieved using a source\nof very non-relativistic electrons at the resonant coupling with the graphene\nplasmons. Due to the strongly confined graphene plasmons, the upconversion of\nmid-infrared to extreme UV radiation can be achieved with the mildly\nrelativistic electron beams. The latter is a promising mechanism for the\ntabletop short-wavelength free electron nanolaser."
    },
    {
        "anchor": "Full-counting statistics of transient energy current in mesoscopic\n  systems: We investigate the full-counting statistics (FCS) of energy flow carried by\nelectrons in the transient regime. Based on two measurement scheme we formulate\na non-equilibrium Keldysh Green's function theory to compute the generating\nfunction for FCS of energy transport. Specifically, we express the generating\nfunction using the path integral along Keldysh contour and obtain exact\nsolution of the generating function using the Grassmann algebra. With this\nformalism, we calculate the transient energy current and higher order cumulants\nfor both single and double quantum dot (QD) systems in the transient regime. To\nexamine finite bandwidth effect of leads to FCS of energy transport, we have\nused an exact solvable model with a Lorentizian linewidth where all\nnon-equilibrium Green's functions can be solved exactly in the time domain. It\nis found that the transient energy current exhibits damped oscillatory\nbehavior. For the single quantum dot system the frequency of oscillation is\nindependent of bandwidth of the leads while the decay rate of the oscillation\namplitude is determined by the lifetime of resonant state which increases as\nthe bandwidth decreases. At short times, a universal scaling of maximum\namplitude of normalized cumulants is identified for the single QD system. For\nthe double QD system, the damped oscillation of energy current is dominated by\nRabi oscillation with frequency approximately proportional to the coupling\nconstant between two quantum dots. In general, the transient energy current\nincreases when the coupling between two QDs is stronger. However, when the\ninterdot coupling is larger than half of the external bias the transient energy\ncurrent is suppressed significantly. All these results can be understood\nanalytically.",
        "positive": "Multi-terminal far-from-equilibrium thermoelectric nano-devices in the\n  Kondo regime: The quest for good thermoelectric materials and/or high-efficiency\nthermoelectric devices is of primary importance from theoretical and practical\npoints of view. Low-dimensional structures with quantum dots or molecules are\npromising candidates to achieve the goal. Interactions between electrons,\nfar-from-equilibrium conditions and strongly non-linear transport are important\nfactors affecting the usefulness of the devices. This paper analyses the\nthermoelectric power of a two-terminal quantum dot under large thermal $\\Delta\nT$ and voltage $V$ biases as well as the performance of the three-terminal\nsystem as a heat engine. To properly characterise the non-linear effects under\nthese conditions, two different Seebeck coefficients are introduced,\ngeneralizing the linear response expression. The direct calculations of\nthermally induced electric and heat currents show, in agreement with recent\nwork, that the efficiency of the thermoelectric heat engine as measured by the\ndelivered power is maximal far from equilibrium. Moreover, the strong Coulomb\ninteractions between electrons on the quantum dot are found to diminish the\nefficiency at maximum power and the maximal value of the delivered power, both\nin the Kondo regime and outside of it."
    },
    {
        "anchor": "Type-II Dirac surface states in topological crystalline insulators: We study the properties of a family of anti-pervoskite materials, which are\ntopological crystalline insulators with an insulating bulk but a conducting\nsurface. Using ab-initio DFT calculations, we investigate the bulk and surface\ntopology and show that these materials exhibit type-I as well as type-II Dirac\nsurface states protected by reflection symmetry. While type-I Dirac states give\nrise to closed circular Fermi surfaces, type-II Dirac surface states are\ncharacterized by open electron and hole pockets that touch each other. We find\nthat the type-II Dirac states exhibit characteristic van-Hove singularities in\ntheir dispersion, which can serve as an experimental fingerprint. In addition,\nwe study the response of the surface states to magnetic fields.",
        "positive": "Quantum beats of coherent 1s 2s excitons in two dimensional transition\n  metal: Motivated by recent experimental measurement of the intrinsic excitonic\nwave-function in 2D Transition-metal dichalcogenides (TMDs) by angle-resolved\nphotoemission spectroscopy (ARPES), we developed a theoretical study to resolve\nsome characteristics of these excitons and some of the many open issues in\nthese systems. The system is assumed to be embedded in an environment with\naverage dielectric constant, below which electrostatic interactions in the\ncorresponding TMD layer are screened. We adopt the long range approximation,\nwhich gives the electron-hole interaction in the Rytova - Keldysh form. Latter\nallows understanding the role of screening in TMDs structures. The bound state\n1s 2s energy eigenvalues for the twodimensional are reformulated in momentum\nspace leads to an integral form of the Wannier equation. The eigenfunctions are\nthen expanded in terms of spherical harmonics. To evaluate the dynamic of the\nangle resolved photoemission spectrum arising from the dissociation of excitons\ngiven their steady states 1s 2s expressions, we follow the semi perturbative\ntheoretical description developed by previous calculations. We discuss the\ndielectric environment effect on the dispersive features of the spectrum for\ndifferent 1s and 2s exciton distributions. Quantum beat signatures in\nphotoemission intensity demonstrate coherent coupling between 1s and 2s\nexcitons. The beating contribution due to excitonic coherence is also\ndiscussed. The periodic oscillations arising from coherent superposition\nstates, quantum beats, enable exploration of novel coherent phenomena."
    },
    {
        "anchor": "Electronic standing waves on the surface of the topological insulator\n  Bi2Te3: A line defect on a metallic surface induces standing waves in the electronic\nlocal density of states (LDOS). Asymptotically far from the defect, the wave\nnumber of the LDOS oscillations at the Fermi energy is usually equal to the\ndistance between nesting segments of the Fermi contour, and the envelope of the\nLDOS oscillations shows a power-law decay as moving away from the line defect.\nHere, we theoretically analyze the LDOS oscillations close to a line defect on\nthe surface of the topological insulator Bi2Te3, and identify an important\npre-asymptotic contribution with wave number and decay characteristics markedly\ndifferent from the asymptotic contributions. Wave numbers characterizing the\npre-asymptotic LDOS oscillations are in good agreement with recent data from\nscanning tunneling microscopy experiments [Phys. Rev. Lett. 104, 016401\n(2010)].",
        "positive": "Giant optical nonlinearity of Fermi polarons in atomically thin\n  semiconductors: Realizing strong nonlinear optical responses is a long-standing goal of both\nfundamental and technological importance. Recently significant efforts have\nfocused on exploring excitons in solids as a pathway to achieving\nnonlinearities even down to few-photon levels. However, a crucial tradeoff\narises as strong light-matter interactions require large oscillator strength\nand short radiative lifetime of the excitons, which limits their interaction\nstrength and nonlinearity. Here we experimentally demonstrate strong nonlinear\noptical responses by exploiting the coupling between excitons and carriers in\nan atomically thin semiconductor of trilayer tungsten diselenide. By\ncontrolling the electric field and electrostatic doping of the trilayer, we\nobserve the hybridization between intralayer and interlayer excitons along with\nthe formation of Fermi polarons due to the interactions between excitons and\nfree carriers. We find substantial optical nonlinearity can be achieved under\nboth continuous wave and pulsed laser excitation, where the resonance of the\nhole-doped Fermi polaron blueshifts by as much as ~10 meV. Intriguingly, we\nobserve a remarkable asymmetry in the optical nonlinearity between electron and\nhole doping, which is tunable by the applied electric field. We attribute these\nfeatures to the strong interactions between excitons and free charges with\noptically induced valley polarization. Our results establish that atomically\nthin heterostructures are a highly versatile platform for engineering nonlinear\noptical response with applications to classical and quantum optoelectronics,\nand open avenues for exploring many-body physics in hybrid Fermionic-Bosonic\nsystems."
    },
    {
        "anchor": "Generation of Squeezed States of Nanomechanical Resonators by Reservoir\n  Engineering: An experimental demonstration of a non-classical state of a nanomechanical\nresonator is still an outstanding task. In this paper we show how the resonator\ncan be cooled and driven into a squeezed state by a bichromatic microwave\ncoupling to a charge qubit. The stationary oscillator state exhibits a reduced\nnoise in one of the quadrature components by a factor of 0.5 - 0.2. These\nvalues are obtained for a 100 MHz resonator with a Q-value of 10$^4$ to 10$^5$\nand for support temperatures of T $\\approx$ 25 mK. We show that the coupling to\nthe charge qubit can also be used to detect the squeezed state via measurements\nof the excited state population. Furthermore, by extending this measurement\nprocedure a complete quantum state tomography of the resonator state can be\nperformed. This provides a universal tool to detect a large variety of\ndifferent states and to prove the quantum nature of a nanomechanical\noscillator.",
        "positive": "Edge States and Interferometers in the Pfaffian and anti-Pfaffian States: We compute the tunneling current in a double point contact geometry of a\nQuantum Hall system at filling fraction $\\nu=5/2$, as function of voltage and\ntemeprature, in the weak tunneling regime. We quantitatively compare two\npossible candidates for the state at $\\nu=5/2$: the Moore-Read Pfaffian state,\nand its particle-hole conjugate, the anti-Pfaffian. We find that both\npossibilities exhibit the same qualitative behavior, and both have an even-odd\neffect that reflects their non-Abelian nature, but differ quantitatively in\ntheir voltage and temperature dependance."
    },
    {
        "anchor": "Calculation of the Self-energy of Open Quantum Systems: We propose an easy method of calculating the self-energy of semi-infinite\nleads attached to a mesoscopic system.",
        "positive": "Curved-space Dirac description of elastically deformed monolayer\n  graphene is generally incorrect: Undistorted monolayer graphene has energy bands which cross at protected\nDirac points. It elastically deforms and much research has assumed the Dirac\ndescription persists, now in a curved space and coupled to a gauge field\nrelated to lattice strain. We show this is incorrect by using a real space\ngradient expansion to study how the Dirac equation derives from the tight\nbinding model. Generic spatially varying hopping functions give rise to large\nmagnetic fields which spoil the truncation in derivatives. In the perturbative\nregime, the only consistent truncation to Dirac is one with nontrivial gauge\nfield but in flat space. One can instead fine tune the magnetic field to be\nsmall, and we derive the resulting differential condition that the hopping\nfunctions must satisfy to yield a consistent truncation to Dirac in curved\nspace. We consider whether mechanical effects might impose this fine tuning,\nbut find this is not the case for a simple elastic membrane model."
    },
    {
        "anchor": "Exciton-polaritons in transition-metal dichalcogenides and their direct\n  excitation via energy transfer: Excitons, composite electron-hole quasiparticles, are known to play an\nimportant role in optoelectronic phenomena in many semiconducting materials.\nRecent experiments and theory indicate that the band-gap optics of the newly\ndiscovered monolayer transition-metal dichalcogenides (TMDs) is dominated by\ntightly bound valley excitons. The strong interaction of excitons with\nlong-range electromagnetic fields in these 2D systems can significantly affect\ntheir intrinsic properties. Here, we develop a semi-classical framework for\nintrinsic exciton-polaritons in monolayer TMDs that treats their dispersion and\nradiative decay on the same footing and can incorporate effects of the\ndielectric environment. It is demonstrated how both inter- and intra-valley\nlong-range interactions influence the dispersion and decay of the polaritonic\neigenstates. We also show that exciton-polaritons can be efficiently excited\nvia resonance energy transfer from quantum emitters such as quantum dots, which\nmay be useful for various applications.",
        "positive": "Composite Topological Excitations in Ferromagnet-Superconductor\n  Heterostructures: We investigate the formation of a new type of composite topological\nexcitation -- the skyrmion-vortex pair (SVP) -- in hybrid systems consisting of\ncoupled ferromagnetic and superconducting layers. Spin-orbit interaction in the\nsuperconductor mediates a magnetoelectric coupling between the vortex and the\nskyrmion, with a sign (attractive or repulsive) that depends on the topological\nindices of the constituents. We determine the conditions under which a bound\nSVP is formed, and characterize the range and depth of the effective binding\npotential through analytical estimates and numerical simulations. Furthermore,\nwe develop a semiclassical description of the coupled skyrmion-vortex dynamics\nand discuss how SVPs can be controlled by applied spin currents."
    },
    {
        "anchor": "Rectangular Potential Barrier Affected by External Fields, Hydrostatic\n  Pressure and Impurities: In this work the influence of the electric and magnetic fields over a\ntunneling particle in a rectangular potential barrier is shown, we have taken\ninto account the presence of an impurity at the barrier center and the effects\nof a hydrostatic pressure parallel to the barrier height considering the\nBenDaniel-Duke boundary conditions. Given that the particle is moving inside a\nGaAs-AlxGa1-xAs-GaAs heterostructures it is evident a change in the\ntransmission coefficient due to the impurity concentration and the presence of\nthe hydrostatic pressure. The potential due to the presence of the impurity is\napproximate with a second degree polynomial function that resolves the\ndiscontinuity generated by heavily modifying the transmission coefficient.",
        "positive": "Tunable exchange bias effect in magnetic\n  Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$ nanoparticles at temperatures\n  up to 250 K: The exchange bias (EB) effect has been observed in magnetic\nBi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$ nanoparticles. The influence of\nmagnetic field cooling on the exchange bias effect has also been investigated.\nThe magnitude of the exchange bias field ($H_{EB}$) increases with the cooling\nmagnetic field, showing that the strength of the exchange bias effect is\ntunable by the field cooling. The $H_{EB}$ values are also found to be\ndependent on the temperature. This magnetically tunable exchange bias obtained\nat temperatures up to 250 K in Bi$_{0.9}$Gd$_{0.1}$Fe$_{0.9}$Ti$_{0.1}$O$_3$\nnanoparticles may be worthwhile for potential applications."
    },
    {
        "anchor": "Anisotropic ground states of the quantum Hall system with currents: Anisotropic states at half-filled higher Landau levels are investigated in\nthe system with a finite electric current. We study the response of the striped\nHall state and the anisotropic charge density wave (ACDW) state against the\ninjected current using the effective action. Current distributions and a\ncurrent dependence of the total energy are determined for both states. With no\ninjected current, the energy of the ACDW state is lower than that of the\nstriped Hall state. We find that the energy of the ACDW state increases faster\nthan that of the striped Hall state as the injected current increases. Hence,\nthe striped Hall state becomes the lower energy state when the current exceeds\nthe critical value. The critical value is estimated at about 0.04-0.07 nA,\nwhich is much smaller than the current used in the experiments.",
        "positive": "Fully tunable longitudinal spin-photon interactions in Si and Ge quantum\n  dots: Spin qubits in silicon and germanium quantum dots are promising platforms for\nquantum computing, but entangling spin qubits over micrometer distances remains\na critical challenge. Current prototypical architectures maximize transversal\ninteractions between qubits and microwave resonators, where the spin state is\nflipped by nearly resonant photons. However, these interactions cause\nback-action on the qubit, that yield unavoidable residual qubit-qubit couplings\nand significantly affect the gate fidelity. Strikingly, residual couplings\nvanish when spin-photon interactions are longitudinal and photons couple to the\nphase of the qubit. We show that large longitudinal interactions emerge\nnaturally in state-of-the-art hole spin qubits. These interactions are fully\ntunable and can be parametrically modulated by external oscillating electric\nfields. We propose realistic protocols to measure these interactions and to\nimplement fast and high-fidelity two-qubit entangling gates. These protocols\nwork also at high temperatures, paving the way towards the implementation of\nlarge-scale quantum processors."
    },
    {
        "anchor": "Graphene-like quaternary compound SiBCN: a new wide direct band gap\n  semiconductor predicted by a first-principles study: Due to the lack of two-dimensional silicon-based semiconductors and the fact\nthat most of the components and devices are generated on single-crystal silicon\nor silicon-based substrates in modern industry, designing two-dimensional\nsilicon-based semiconductors is highly desired. With the combination of a swarm\nstructure search method and density functional theory in this work, a\nquaternary compound SiBCN with graphene-like structure is found and displays a\nwide direct band gap as expected. The band gap is of ~2.63 eV which is just\nbetween ~2.20 and ~3.39 eV of the highlighted semiconductors SiC and GaN.\nNotably, the further calculation reveals that SiBCN possesses high carrier\nmobility with ~5.14x10^3 and ~13.07x10^3 cm^2V^-1s^-1 for electron and hole,\nrespectively. Furthermore, the ab initio molecular dynamics simulations also\nshow that the graphene-like structure of SiBCN can be well kept even at an\nextremely high temperature of 2000 K. The present work tells that designing\nulticomponent silicides may be a practicable way to search for new\nsilicon-based low-dimensional semiconductors which can match well with the\nprevious Si-based substrates.",
        "positive": "Atomic scale characterization of graphene p-n junctions for\n  electron-optical applications: Graphene p-n junctions offer a potentially powerful approach towards\ncontrolling electron trajectories via collimation and focusing in ballistic\nsolid-state devices. The ability of p-n junctions to control electron\ntrajectories depends crucially on the doping profile and roughness of the\njunction. Here, we use four-probe scanning tunneling microscopy and\nspectroscopy (STM/STS) to characterize two state-of-the-art graphene p-n\njunction geometries at the atomic scale, one with CMOS polySi gates and another\nwith naturally cleaved graphite gates. Using spectroscopic imaging, we\ncharacterize the local doping profile across and along the p-n junctions. We\nfind that realistic junctions exhibit non-ideality both in their geometry as\nwell as in the doping profile across the junction. We show that the geometry of\nthe junction can be improved by using the cleaved edge of van der Waals metals\nsuch as graphite to define the junction. We quantify the geometric roughness\nand doping profiles of junctions experimentally and use these parameters in\nNonequilibrium Green's Function based simulations of focusing and collimation\nin these realistic junctions. We find that for realizing Veselago focusing, it\nis crucial to minimize lateral interface roughness which only natural graphite\ngates achieve, and to reduce junction width, in which both devices under\ninvestigation underperform. We also find that carrier collimation is currently\nlimited by the non-linearity of the doping profile across the junction. Our\nwork provides benchmarks of the current graphene p-n junction quality and\nprovides guidance for future improvements."
    },
    {
        "anchor": "Non-equilibrium molecular dynamics and continuum modelling of transient\n  freezing of atomistic solids: In this work we investigate the transient solidification of a Lennard-Jones\nliquid using non-equilibrium molecular dynamics simulations and continuum heat\ntransfer theory. The simulations are performed in slab-shaped boxes, where a\ncold thermostat placed at the centre of the box drives the solidification of\nthe liquid. Two well-defined solid fronts propagate outwards from the centre\ntowards the ends of the box until solidification is completed. A continuum\nphase change model that accounts for the difference between the solid and the\nliquid densities is formulated to describe the evolution of the temperature and\nthe position of the solidification front. Simulation results for a small and a\nlarge nanoscale system, of sizes $30.27$\\,nm and $60.54$\\,nm, are compared with\nthe predictions of the theoretical model. Following a transient period of\n$\\sim$20-40 ps and a displacement of the solidification front of 1-2.5 nm we\nfind that the simulations and the continuum theory show good agreement. We use\nthis fact to combine the simulation and theoretical approaches to design a\nsimple procedure to calculate the latent heat of the material. We also perform\nsimulations of the homogeneous freezing process, i.e. in the absence of a\ntemperature gradient and at constant temperature, by quenching the liquid at\nsupercooled temperatures. We demonstrate that the solidification rate of\nhomogenous freezing is much faster than the one obtained under a thermal\ngradient for systems of the same size subject to the same thermostat\ntemperature. Our study and conclusions should be of general interest to a wide\nrange of atomistic solids.",
        "positive": "Insulating behavior in ultra-thin bismuth selenide field effect\n  transistors: Ultrathin (~3 quintuple layer) field-effect transistors (FETs) of topological\ninsulator Bi2Se3 are prepared by mechanical exfoliation on 300nm SiO2/Si\nsusbtrates. Temperature- and gate-voltage dependent conductance measurements\nshow that ultrathin Bi2Se3 FETs are n-type, and have a clear OFF state at\nnegative gate voltage, with activated temperature-dependent conductance and\nenergy barriers up to 250 meV."
    },
    {
        "anchor": "Interfacial Fermi Loops from Interfacial Symmetries: We propose a concept of interfacial symmetries such as interfacial\nparticle-hole symmetry and interfacial time-reversal symmetry, which appear in\ninterfaces between two regions related to each other by particle-hole or\ntime-reversal transformations. These symmetries result in novel dispersion of\ninterface states. In particular for the interfacial particle-hole symmetry the\ngap closes along a loop (\"Fermi loop\") at the interface. We numerically\ndemonstrate this for the Fu-Kane-Mele tight-binding model. We show that the\nFermi loop originates from a sign change of a Pfaffian of a product between the\nHamiltonian and a constant matrix.",
        "positive": "Photoassisted tunneling from free-standing GaAs thin films into metallic\n  surfaces: The tunnel photocurrent between a gold surface and a free-standing\nsemiconducting thin film excited from the rear by above bandgap light has been\nmeasured as a function of applied bias, tunnel distance and excitation light\npower. The results are compared with the predictions of a model which includes\nthe bias dependence of the tunnel barrier height and the bias-induced decrease\nof surface recombination velocity. It is found that i) the tunnel photocurrent\nfrom the conduction band dominates that from surface states. ii) At large\ntunnel distance the exponential bias dependence of the current is explained by\nthat of the tunnel barrier height, while at small distance the change of\nsurface recombination velocity is dominant."
    },
    {
        "anchor": "Explanation for the isotropy of the Dirac cone in graphene: It is shown that in the absence of spontaneous symmetry breaking the Dirac\ncones in the system of interacting electrons on honeycomb lattice are isotropic\nat low energies. The effect is due to the $Z_3$ subgroup of the $D_3$ symmetry\ngroup of the dispersion relation of Dirac quasiparticles. Consequences of the\nviolations of the $Z_3$ or the sublattice symmetry are discussed.",
        "positive": "Entangled photon pairs from a quantum dot cascade decay: the effect of\n  time-reordering: Coulomb interactions between confined carriers remove degeneracies in the\nexcitation spectra of quantum dots. This provides a which path information in\nthe cascade decay of biexcitons, thus spoiling the energy-polarization\nentanglement of the emitted photon pairs. We theoretically analyze a strategy\nof color coincidence across generation (AG), recently proposed as an\nalternative to the previous, within generation (WG) approach. We simulate the\nsystem dynamics and compute the correlation functions within the density-matrix\nformalism. This allows to estimate quantities that are accessible by a\npolarization-tomography experiment, and that enter the expression of the\ntwo-photon concurrence. We identify the optimum parameters within the AG\napproach, and the corresponding maximum values of the concurrence."
    },
    {
        "anchor": "Magneto-resistance up to 60 Tesla in Topological Insulator Bi2Te3 Thin\n  Films: We report magneto-transport studies of topological insulator Bi_{2}Te_{3}\nthin films grown by pulsed laser deposition. A non-saturating linear-like\nmagneto-resistance (MR) is observed at low temperatures in the magnetic field\nrange from a few Tesla up to 60 Tesla. We demonstrate that the strong\nlinear-like MR at high field can be well understood as the weak\nantilocalization phenomena described by Hikami-Larkin-Nagaoka theory. Our\nanalysis suggests that in our system, a topological insulator, the elastic\nscattering time can be longer than the spin-orbit scattering time. We briefly\ndiscuss our results in the context of Dirac Fermion physics and 'quantum linear\nmagnetoresistance'.",
        "positive": "Stimulated emission depletion spectroscopy of color centers in hexagonal\n  boron nitride: We demonstrate the use of Stimulated Emission Depletion (STED) spectroscopy\nto map the electron-optical-phonon sideband of the ground state of the\nradiative transition of color centers in hexagonal boron nitride emitting at\n2.0-2.2 eV, with in-plane linear polarization. The measurements are compared to\nPhotoluminescence of Excitation (PLE) spectra, that maps the\nelectron-optical-phonon sideband of the excited state. The main qualitative\ndifference is a red-shift in the longitudinal optical phonon peak associated\nwith $E_{1u}$ symmetry at the zone center. We argue that this is consistent\nwith recent findings for a carbon-based line defect with admixture of\nenergetically similar excited states."
    },
    {
        "anchor": "Low-dissipation edge currents without edge states: We show that bulk free carriers in topologically trivial multi-valley\ninsulators with non-vanishing Berry curvature give rise to low-dissipation edge\ncurrents, which are squeezed within a distance of the order of the valley\ndiffusion length from the edge. This happens even in the absence of edge states\n[topological (gapless) or otherwise], and when the bulk equilibrium carrier\nconcentration is thermally activated across the gap. Physically, the squeezed\nedge current arises from the spatially inhomogeneous orbital magnetization that\ndevelops from valley-density accumulation near the edge. While this current\npossesses neither topology nor symmetry protection and, as a result, is not\nimmune to dissipation, in clean enough devices it can mimic low-loss ballistic\ntransport.",
        "positive": "Photo-magnonics: In the framework of magnonics all-optical femtosecond laser experiments are\nused to study spin waves and their relaxation paths. Magnonic crystal\nstructures based on antidots allow the control over the spin-wave modes. In\nthese two-dimensional magnetic metamaterials with periodicities in the\nwave-length range of dipolar spin waves the spin-wave bands and dispersion are\nmodified. Hence, a specific selection of spin-wave modes excited by laser\npulses is possible. Different to photonics, the modes depend strongly on the\nstrength of the magneto-static potential at around each antidot site - the\ndipolar field. While this may lead to a mode localization, also for filling\nfractions around or below 10%, Bloch states are found in low damping\nferromagnetic metals. In this chapter, an overview of these mechanisms is given\nand the connection to spin-wave band spectra calculated from an analytical\nmodel is established. Namely, the plane-wave method yields flattened bands as\nwell as band gaps at the antidot lattice Brillouin zone boundary."
    },
    {
        "anchor": "Temporal Oscillation of Conductances in Quantum Hall Effect of Bloch\n  Electrons: We study a nonadiabatic effect on the conductances in the quantum Hall effect\nof two-dimensional electrons with a periodic potential. We found that the Hall\nand longitudinal conductances oscillate in time with a very large frequencies\ndue to quantum fluctuation.",
        "positive": "Realization of Pristine and Locally-Tunable One-Dimensional Electron\n  Systems in Carbon Nanotubes: Recent years have seen the development of several experimental systems\ncapable of tuning local parameters of quantum Hamiltonians. Examples include\nultracold atoms, trapped ions, superconducting circuits, and photonic crystals.\nBy design, these systems possess negligible disorder, granting them a high\nlevel of tunability. Conversely, electrons in conventional condensed matter\nsystems exist inside an imperfect host material, subjecting them to\nuncontrollable, random disorder, which often destroys delicate correlated\nphases and precludes local tunability. The realization of a condensed matter\nsystem that is disorder-free and locally-tunable thus remains an outstanding\nchallenge. Here, we demonstrate a new technique for deterministic creation of\nlocally-tunable, ultra-low-disorder electron systems in carbon nanotubes\nsuspended over circuits of unprecedented complexity. Using transport\nexperiments we show that electrons can be localized at any position along the\nnanotube and that the confinement potential can be smoothly moved from location\nto location. Nearly perfect mirror symmetry of transport characteristics about\nthe centre of the nanotube establishes the negligible effects of electronic\ndisorder, thus allowing experiments in precision engineered one-dimensional\npotentials. We further demonstrate the ability to position multiple nanotubes\nat chosen separations, generalizing these devices to coupled one-dimensional\nsystems. These new capabilities open the door to a broad spectrum of new\nexperiments on electronics, mechanics, and spins in one dimension."
    },
    {
        "anchor": "Thermoelectric and thermal rectification properties of quantum dot\n  junctions: The electrical conductance, thermal conductance, thermal power and figure of\nmerit (ZT) of semiconductor quantum dots (QDs) embedded into an insulator\nmatrix connected with metallic electrodes are theoretically investigated in the\nCoulomb blockade regime. The multilevel Anderson model is used to simulate the\nmultiple QDs junction system. The charge and heat currents in the sequential\ntunneling process are calculated by the Keldysh Green function technique. In\nthe linear response regime the ZT values are still very impressive in the small\ntunneling rates case, although the effect of electron Coulomb interaction on ZT\nis significant. In the nonlinear response regime, we have demonstrated that the\nthermal rectification behavior can be observed for the coupled QDs system,\nwhere the very strong asymmetrical coupling between the dots and electrodes,\nlarge energy level separation between dots and strong interdot Coulomb\ninteractions are required.",
        "positive": "Orbital diffusion, polarization and swapping in centrosymmetric metals: We propose a general theory of charge, spin and orbital diffusion based on\nKeldysh formalism. Our findings indicate that the diffusivity of orbital\nangular momentum in metals is much lower than that of spin or charge due to the\nstrong orbital intermixing in crystals. Furthermore, our theory introduces the\nconcept of spin-orbit polarization by which a pure orbital (spin) current\ninduces a longitudinal spin (orbital) current, a process as efficient as spin\npolarization in ferromagnets. Finally, we find that orbital currents undergo\nmomentum swapping, even in the absence of spin-orbit coupling. This theory\nestablishes several key parameters for orbital transport of direct importance\nto experiments."
    },
    {
        "anchor": "Quasiparticle Interference Studies of Quantum Materials: Exotic electronic states are realized in novel quantum materials. This field\nis revolutionized by the topological classification of materials. Such\ncompounds necessarily host unique states on their boundaries. Scanning\ntunneling microscopy studies of these surface states have provided a wealth of\nspectroscopic characterization, with the successful cooperation of ab initio\ncalculations. The method of quasiparticle interference imaging proves to be\nparticularly useful for probing the dispersion relation of the surface bands.\nHerein, how a variety of additional fundamental electronic properties can be\nprobed via this method is reviewed. It is demonstrated how quasiparticle\ninterference measurements entail mesoscopic size quantization and the\nelectronic phase coherence in semiconducting nanowires; helical spin protection\nand energy-momentum fluctuations in a topological insulator; and the structure\nof the Bloch wave function and the relative insusceptibility of topological\nelectronic states to surface potential in a topological Weyl semimetal.",
        "positive": "Numerical reverse engineering of general spin-wave dispersions: Bridge\n  between numerics and analytics using a dynamic-matrix approach: Modern problems in magnetization dynamics require more and more the numerical\ndetermination of the spin-wave spectra and -dispersion in magnetic systems\nwhere analytic theories are not yet available. Micromagnetic simulations can be\nused to compute the spatial profiles and oscillation frequencies of spin-waves\nin magnetic system with almost arbitrary geometry and different magnetic\ninteractions. Although numerical approaches are very versatile, they often do\nnot give the same insight and physical understanding as analytical theories.\nFor example, it is not always possible to decide whether a certain feature\n(such as dispersion asymmetry, for example) is governed by one magnetic\ninteraction or the other. Moreover, since numerical approaches typically yield\nthe normal modes of the system, it is not always feasible to disentangle\nhybridized modes. In this manuscript, we build a bridge between numerics and\nanalytics by presenting a methodology to calculate the individual contributions\nto general spin-wave dispersions in a fully numerical manner. We discuss the\ngeneral form of any spin-wave dispersion in terms of the effective (stiffness)\nfields produced by the modes. Based on a special type of micromagnetic\nsimulations, the numerical dynamic-matrix approach, we show how to calculate\neach stiffness field in the respective dispersion law, separately for each\nmagnetic interaction. In particular, it becomes possible to disentangle\ncontributions of different magnetic interactions to the dispersion asymmetry in\nsystems where non-reciprocity is present. At the same time, dipolar-hybridized\nmodes can be easily disentangled. Since this method is independent of the\ngeometry or the involved magnetic interactions at hand, we believe it is\nattractive for experimental and theoretical studies of magnetic systems where\nthere are no analytics yet, but also to aid the development of new analytical\ntheories."
    },
    {
        "anchor": "Resonances in dissipative optomechanics with nanoparticles: Sorting,\n  speed rectification and transverse cooling: The interaction between dielectric particles and a laser-driven optical\ncavity gives rise to both conservative and dissipative dynamics, which can be\nused to levitate, trap and cool nanoparticles. We analytically and numerically\nstudy a two-mode setup in which the optical potentials along the cavity axis\ncancel, so that the resulting dynamics is almost purely dissipative. For\nappropriate detunings of the laser-drives, this dissipative optomechanical\ndynamics can be used to sort particles according to their size, to rectify\ntheir velocities and to enhance transverse cooling.",
        "positive": "Electron-photon Chern number in cavity-embedded 2D moir\u00e9 materials: We explore theoretically how the topological properties of 2D materials can\nbe manipulated by cavity quantum electromagnetic fields for both resonant and\noff-resonant electron-photon coupling, with a focus on van der Waals moir\\'e\nsuperlattices. We investigate an electron-photon topological Chern number for\nthe cavity-dressed energy minibands that is well defined for any degree of\nhybridization of the electron and photon states. While an off-resonant cavity\nmode can renormalize electronic topological phases that exist without cavity\ncoupling, we show that when the cavity mode is resonant to electronic miniband\ntransitions, new and higher electron-photon Chern numbers can emerge."
    },
    {
        "anchor": "Linear magnetoresistance in topological insulators: Quantum phase\n  coherence effects at high temperatures: In addition to the weak antilocalization cusp observed in the\nmagnetoresistance (MR) of topological insulators at low temperatures and low\nmagnetic fields, we find that the high-field MR in Bi2Te2Se is linear in field.\nAt fields up to B=14T the slope of this linear-like MR is nearly independent of\ntemperature over the range T=7 to 150K. We find that the linear MR arises from\nthe competition between a logarithmic phase coherence component and a quadratic\ncomponent. The quantum phase coherence dominates up to high temperatures, where\nthe coherence length remains longer than the mean free path of electrons.",
        "positive": "Excitation gap of a graphene channel with superconducting boundaries: We calculate the density of states of electron-hole excitations in a\nsuperconductor/normal-metal/superconductor (SNS) junction in graphene, in the\nlong-junction regime that the superconducting gap is much larger than the\nThouless energy. If the normal region is undoped, the excitation spectrum\nconsists of neutral modes that propagate along the boundaries - transporting\nenergy but no charge. These ``Andreev modes'' are a coherent superposition of\nelectron states from the conduction band and hole states from the valence band,\ncoupled by specular Andreev reflection at the superconductor. The lowest\nAndreev mode has an excitation gap, which depends on the superconducting phase\ndifference across the SNS graphene channel. At high doping the excitation gap\nvanishes and the usual gapless density of states of Andreev levels is\nrecovered. We use our results to calculate the superconducting phase dependence\nof the thermal conductance of the graphene channel."
    },
    {
        "anchor": "Large spin current generation by the spin Hall effect in mixed\n  crystalline phase Ta thin films: Manipulation of the magnetization in heavy-metal/ferromagnetic bilayers via\nthe spin-orbit torque requires high spin Hall conductivity of the heavy metal.\nWe measure inverse spin Hall voltage using a co-planar wave-guide based\nbroadband ferromagnetic resonance set-up in Py/Ta system with varying\ncrystalline phase of Ta. We demonstrate a strong correlation between the\nmeasured spin mixing conductance and spin Hall conductivity with the\ncrystalline phase of Ta thin films. We found a large spin Hall conductivity of\n$-2439~(\\hbar/e)~\\Omega^{-1}$cm$^{-1}$ for low-resistivity (68 $\\mu\\Omega-$cm)\nTa film having mixed crystalline phase, which we attribute to an extrinsic\nmechanism of the spin Hall effect.",
        "positive": "STM-induced desorption and lithographic patterning of Cl-Si(100)-(2x1): We investigated STM-induced chlorine desorption and lithographic patterning\nof Cl-terminated Si(100)-(2x1) surfaces at sample temperatures from 4 K to 600\nK. STM lithography has previously focused on hydrogen-based chemistry for donor\ndevice fabrication. Here, to develop halogen-based chemistries for fabricating\nacceptor-based devices, we substituted the hydrogen resist with chlorine.\nLithographic patterning was explored using both field emission patterning to\ndesorb chlorine from large areas as well as atomic precision patterning to\ndesorb chlorine along one to two dimer rows at a time. We varied the\nexperimental parameters for lithographic patterning and found a positive\ncorrelation between pattern line widths and both sample bias voltage and total\nelectron dose. Finally, the use of chlorine, bromine, and iodine as\nlithographic resists to broaden the range of available chemistries for future\ndevice fabrication utilizing halogen-based dopant precursors is discussed."
    },
    {
        "anchor": "Aharonov-Casher and spin Hall effects in two-dimensional mesoscopic ring\n  structures with strong spin-orbit interaction: We study the quantum interference effects induced by the Aharonov-Casher\nphase in asymmetrically confined two-dimensional electron and heavy-hole ring\nstructures systems taking into account the electrically tunable spin-orbit (SO)\ninteraction. We have calculated the non-adiabatic transport properties of\ncharges (heavy-holes and electrons) in two-probe thin ring structures and\ncompare how the form of the SO coupling of the carries affects it. We show that\nboth the SO splitting of the bands and the carrier density can be used to\nmodulate the conductance through the ring. We show that the dependence on\ncarrier density is due to the backscattering from the leads which shows\npronounce resonances when the Fermi energy is close to the eigenenergy of the\nring. We also calculate the spin Hall conductivity and longitudinal\nconductivity in four-probe rings as a function of the carrier density and SO\ninteraction, demonstrating that for heavy-hole carriers both conductivities are\nlarger than for electrons. Finally, we investigate the transport properties of\nmesoscopic rings with spatially inhomogeneous SO coupling. We show that devices\nwith inhomogeneous SO interaction exhibit an electrically controlled\nspin-flipping mechanism.",
        "positive": "Collective properties of indirect excitons in coupled quantum wells in\n  random field: The influence of a random field induced by impurities, boundary\nirregularities etc. on the superfluidity of a quasi-two-dimensional (2D) system\nof spatially indirect excitons in coupled quantum wells is studied. The\ninteraction between excitons is taken into account in the ladder approximation.\nThe random field is allowed to be large compared to the dipole-dipole repulsion\nbetween excitons. The coherent potential approximation (CPA) allows us to\nderive the exciton Green's function for a wide range of the random field, and\nthe CPA results are used in the weak-scattering limit, which results in the\nsecond-order Born approximation. The Green's function of the collective\nexcitations for the cases of (1) equal electron and hole masses and (2) the\n``heavy hole'' limit are derived analytically. For quasi-two-dimensional\nexcitonic systems, the density of the superfluid component and the\nKosterlitz-Thouless temperature of the superfluid phase transition are\nobtained, and are found to decrease as the random field increases. This puts\nconstraints on the experimental efforts to observe excitonic superfluidity."
    },
    {
        "anchor": "Injection terahertz laser using the resonant inter-layer radiative\n  transitions in double-graphene-layer structure: We propose and substantiate the concept of terahertz (THz) laser enabled by\nthe resonant electron radiative transitions between graphene layers (GLs) in\ndouble-GL structures. We estimate the THz gain for TM-mode exhibiting very low\nDrude absorption in GLs and show that the gain can exceed the losses in\nmetal-metal waveguides at the low end of the THz range. The spectrum of the\nemitted photons can be tuned by the applied voltage. A weak temperature\ndependence of the THz gain promotes an effective operation at room temperature.",
        "positive": "Spin and e-e interactions in quantum dots: Leading order corrections to\n  universality and temperature effects: We study the statistics of the spacing between Coulomb blockade conductance\npeaks in quantum dots with large dimensionless conductance g. Our starting\npoint is the ``universal Hamiltonian''--valid in the g->oo limit--which\nincludes the charging energy, the single-electron energies (described by random\nmatrix theory), and the average exchange interaction. We then calculate the\nmagnitude of the most relevant finite g corrections, namely, the effect of\nsurface charge, the ``gate'' effect, and the fluctuation of the residual e-e\ninteraction. The resulting zero-temperature peak spacing distribution has\ncorrections of order Delta/sqrt(g). For typical values of the e-e interaction\n(r_s ~ 1) and simple geometries, theory does indeed predict an asymmetric\ndistribution with a significant even/odd effect. The width of the distribution\nis of order 0.3 Delta, and its dominant feature is a large peak for the odd\ncase, reminiscent of the delta-function in the g->oo limit. We consider finite\ntemperature effects next. Only after their inclusion is good agreement with the\nexperimental results obtained. Even relatively low temperature causes large\nmodifications in the peak spacing distribution: (a) its peak is dominated by\nthe even distribution at kT ~ 0.3 Delta (at lower T a double peak appears); (b)\nit becomes more symmetric; (c) the even/odd effect is considerably weaker; (d)\nthe delta-function is completely washed-out; and (e) fluctuation of the\ncoupling to the leads becomes relevant. Experiments aimed at observing the T=0\npeak spacing distribution should therefore be done at kT<0.1 Delta for typical\nvalues of the e-e interaction."
    },
    {
        "anchor": "Transport properties of a 1000-nm HgTe film: the interplay of surface\n  and bulk carriers: We report on systematic study of transport properties of a 1000-nm HgTe film.\nUnlike to thinner and strained HgTe films, which are known as high-quality\nthree-dimensional (3D) topological insulators, the film under study is much\nthicker than the limit of pseudomorphic growth of HgTe on a CdTe substrate.\nTherefore, it is expected to be fully relaxed and has the band structure of\nbulk HgTe, i.e., a zero gap semiconductor. Nevertheless, since the bands\ninversion the two-dimensional (2D) topological surface states are still\nexpected to exist. To check this claim we studied classical and quantum\ntransport response of the system. We demonstrate that by tuning the top-gate\nvoltage one can change the electron-dominating transport to the hole one. The\nhighest electron mobility is found to be more than $300 \\times 10^3$ cm$^2$/Vs.\nThe system exhibits Shubnikov-de Haas (SdH) oscillations with a complicated\npattern and shows up to 5 independent frequencies in corresponding Fourier\nspectra. They are attributed to the topological surface states,\nVolkov-Pankratov states and spin-degenerate bulk states in the accumulation\nlayer near the gate. The observed peculiarities of the quantum transport are\nthe strong SdH oscillations of the Hall resistance, and the suppressed\noscillatory response of the topological surface states.",
        "positive": "Transport in Fermi Liquids Confined by Rough Walls: I present theoretical calculations of the thermal conductivity of Fermi\nliquid 3He confined to a slab of thickness of order 100nm. The effect of the\nroughness of the confining surfaces is included directly in terms of the\nsurface roughness power spectrum which may be determined experimentally.\nTransport at low temperatures is limited by scattering off rough surfaces and\nevolves into the known high-temperature limit in bulk through an anomalous\nregime in which both inelastic quasiparticle scattering and elastic scattering\noff the rough surface coexist. I show preliminary calculations for the\ncoefficients of thermal conductivity. These studies are applicable in the\ncontext of electrical transport in metal nanowires as well as experiments that\nprobe the superfluid phase diagram of liquid 3He in a slab geometry."
    },
    {
        "anchor": "Periodic instanton method and macroscopic quantum tunneling between two\n  weakly-linked Bose-Einstein condensates: A new method is used to investigate the tunneling between two weakly-linked\nBose-Einstein condensates confined in double-well potential traps. The\nnonlinear interaction between the atoms in each well contributes to a finite\nchemical potential, which, with consideration of periodic instantons, leads to\na remarkably high tunneling frequency. This result can be used to interpret the\nnewly found Macroscopic Quantum Self Trapping (MQST) effect. Also a new kind of\nfirst-order crossover between different regions is predicted.",
        "positive": "Large transverse Hall-like signal in topological Dirac semimetal Cd3As2: Cadmium arsenide ($\\rm Cd_3As_2$) is known for its inverted band structure\nand ultra-high electron mobility. It has been theoretically predicted and also\nconfirmed by ARPES experiments to exhibit a 3D Dirac semimetal phase containing\ndegenerate Weyl nodes. From magneto-transport measurements in high quality\nsingle crystals of $\\rm Cd_3As_2$, a small effective mass $m^* \\approx$ 0.05\n$m_e$ is determined from the Shubnikov-de Haas (SdH) oscillations. In certain\nfield orientations, we find a splitting of the SdH oscillation frequency in the\nFFT spectrum suggesting a possible lifting of the double degeneracy in accord\nwith the helical spin texture at outer and inner Fermi surfaces with opposite\nchirality predicted by our \\textit{ab initio} calculations. Strikingly, a large\nantisymmetric magnetoresistance with respect to the applied magnetic fields is\nuncovered over a wide temperature range in needle crystal of $\\rm Cd_3As_2$\nwith its long axis along [112] crystal direction. It reveals a possible\ncontribution of intrinsic anomalous velocity term in the transport equation\nresulting from a unique 3D Rashba-like spin splitted bands that can be obtained\nfrom band calculations with the inclusion of Cd antisite defects."
    },
    {
        "anchor": "Optimal pumping of orbital entanglement with single particle emitters: We propose a method for the optimal time-controlled generation of entangled\nitinerant particles, using on-demand sources in a conductor in the quantum Hall\nregime. This entanglement pump is realized by applying periodic, tailored\nvoltage pulses to pairs of quantum dots or quantum point contacts. We show that\nthe pump can produce orbital Bell pairs of both electrons and holes at the\noptimal rate of half a pair per pumping cycle. The entanglement can be detected\nby a violation of a Bell inequality formulated in terms of low-frequency\ncurrent cross correlations.",
        "positive": "Electron Spin Excited States Spectroscopy in a Quantum Dot Probed by QPC\n  Back-action: The quantum point contact (QPC) back-action has been found to cause\nnon-thermal-equilibrium excitations to the electron spin states in a quantum\ndot (QD). Here we use back-action as an excitation source to probe the spin\nexcited states spectroscopy for both the odd and even electron numbers under a\nvarying parallel magnetic field. For a single electron, we observed the Zeeman\nsplitting. For two electrons, we observed the splitting of the spin triplet\nstates $|T^{+}>$ and $|T^{0}>$ and found that back-action drives the singlet\nstate $|S>$ overwhelmingly to $|T^{+}>$ other than $|T^{0}>$. All these\ninformation were revealed through the real-time charge counting statistics."
    },
    {
        "anchor": "Electron transport in a ferromagnetic/normal/ferromagnetic tunnel\n  junction based on the surface of a topological insulator: We theoretically study the electron transport properties in a\nferromagnetic/normal/ferromagnetic tunnel junction, which is deposited on the\ntop of a topological surface. The conductance at the parallel (\\textbf{P})\nconfiguration can be much bigger than that at the antiparallel (\\textbf{AP})\nconfiguration. Compared \\textbf{P} with \\textbf{AP} configuration, there exists\na shift of phase which can be tuned by gate voltage. We find that the exchange\nfield weakly affects the conductance of carriers for \\textbf{P} configuration\nbut can dramatically suppress the conductance of carriers for \\textbf{AP}\nconfiguration. This controllable electron transport implies anomalous\nmagnetoresistance in this topological spin valve, which may contribute to the\ndevelopment of spintronics . In addition, we find that there is a\nFabry-Perot-like electron interference.",
        "positive": "Spin-dephasing anisotropy for electrons in a diffusive quasi-1D GaAs\n  wire: We present a numerical study of dephasing of electron spin ensembles in a\ndiffusive quasi-one-dimensional GaAs wire due to the D'yakonov-Perel'\nspin-dephasing mechanism. For widths of the wire below the spin precession\nlength and for equal strength of Rashba and linear Dresselhaus spin-orbit\nfields a strong suppression of spin-dephasing is found. This suppression of\nspin-dephasing shows a strong dependence on the wire orientation with respect\nto the crystal lattice. The relevance for realistic cases is evaluated by\nstudying how this effect degrades for deviating strength of Rashba and linear\nDresselhaus fields, and with the inclusion of the cubic Dresselhaus term."
    },
    {
        "anchor": "Electrical noise spectroscopy of magnons in a quantum Hall ferromagnet: Collective spin-wave excitations-magnons-in a quantum Hall ferromagnet are\npromising quasi-particles for next-generation spintronics devices, including\nplatforms for information transfer. Detection of these charge-neutral\nexcitations relies on the conversion of magnons into electrical signals in the\nform of excess electrons and holes, but if these signals are equal the magnon\ndetection remains elusive. In this work, we overcome this shortcoming by\nmeasuring the electrical noise generated by magnons. We use the symmetry-broken\nquantum Hall ferromagnet of the zeroth Landau level in graphene to launch\nmagnons. Absorption of these magnons creates excess noise above the Zeeman\nenergy and remains finite even when the average electrical signal is zero.\nMoreover, we formulate a theoretical model in which the noise is generated by\nequilibration (partial or full, depending on the bias voltage) between edge\nchannels and propagating magnons. Our model, which agrees with experimental\nobservations, also allows us to pinpoint the regime of ballistic magnon\ntransport in our device.",
        "positive": "Current-induced modulation of interfacial Dzyaloshinskii-Moriya\n  interaction: The Dzyaloshinskii-Moriya (DM) interaction is an antisymmetric exchange\ninteraction that is responsible for the emergence of chiral magnetism. The\norigin of the DM interaction, however, remains to be identified albeit the\nlarge number of studies reported on related effects. It has been recently\nsuggested that the DM interaction is equivalent to an equilibrium spin current\ndensity originating from spin-orbit coupling, an effect referred to as the spin\nDoppler effect. The model predicts that the DM interaction can be controlled by\nspin current injected externally. Here we show that the DM exchange constant\n($D$) in W/CoFeB based heterostructures can be modulated with external current\npassed along the film plane. At higher current, $D$ decreases with increasing\ncurrent, which we infer is partly due to the adiabatic spin transfer torque. At\nlower current, $D$ increases linearly with current regardless of the polarity\nof current flow. The rate of increase in $D$ with the current density agrees\nwith that predicted by the model based on the spin Doppler effect. These\nresults imply that the DM interaction at the HM/FM interface partly originates\nfrom an equilibrium interface spin (polarized) current which can be modulated\nexternally."
    },
    {
        "anchor": "Proposal of an experimental scheme for determination of penetration\n  depth of transverse spin current by a nonlocal spin valve: We theoretically propose an experiment to determine the penetration depth of\na transverse spin current using a nonlocal spin valve with three ferromagnetic\n(F) layers, where the F_1, F_2, and F_3 layers act as the spin injector,\ndetector, and absorber, respectively. We show that the penetration depth can be\nevaluated by measuring the dependence of the spin signal (magnetoresistance) on\nthe thickness of the F_3 layer.",
        "positive": "Electromechanical noise in a diffusive conductor: Electrons moving in a conductor can transfer momentum to the lattice via\ncollisions with impurities and boundaries, giving rise to a fluctuating\nmechanical stress tensor. The root-mean-squared momentum transfer per\nscattering event in a disordered metal (of dimension L greater than the mean\nfree path l and screening length xi) is found to be reduced below the Fermi\nmomentum by a factor of order l/L for shear fluctuations and (xi/L)^2 for\npressure fluctuations. The excitation of an elastic bending mode by the shear\nfluctuations is estimated to fall within current experimental sensitivity for a\nnanomechanical oscillator."
    },
    {
        "anchor": "Automated extraction of capacitive coupling for quantum dot systems: Gate-defined quantum dots (QDs) have appealing attributes as a quantum\ncomputing platform. However, near-term devices possess a range of possible\nimperfections that need to be accounted for during the tuning and operation of\nQD devices. One such problem is the capacitive cross-talk between the metallic\ngates that define and control QD qubits. A way to compensate for the capacitive\ncross-talk and enable targeted control of specific QDs independent of coupling\nis by the use of virtual gates. Here, we demonstrate a reliable automated\ncapacitive coupling identification method that combines machine learning with\ntraditional fitting to take advantage of the desirable properties of each. We\nalso show how the cross-capacitance measurement may be used for the\nidentification of spurious QDs sometimes formed during tuning experimental\ndevices. Our systems can autonomously flag devices with spurious dots near the\noperating regime, which is crucial information for reliable tuning to a regime\nsuitable for qubit operations.",
        "positive": "Quantum Wells in Photovoltaic Cells: The fundamental efficiency limit of a single bandgap solar cell is about 31%\nat one sun with a bandgap of about Eg = 1.35 eV (1), determined by the\ntrade-off of maximising current with a smaller bandgap and voltage with a\nlarger bandgap. Multiple bandgaps can be introduced to absorb the broad solar\nspectrum more efficiently. This can be realised in multi- junction cells, for\nexample, where two or more cells are stacked on top of each other either\nmechanically or monolithically connected by a tunnel junction. An alternative\nor complementary (see section 1.4) approach is the quantum well cell (QWC)."
    },
    {
        "anchor": "Broken symmetry, hyper-fermions, and universal conductance in transport\n  through a fractional quantum Hall edge: We have found solution to a model of tunneling between a multi-channel Fermi\nliquid reservoir and an edge of the principal fractional quantum Hall liquid\n(FQHL) in the strong coupling limit. The solution explains how the absence of\nthe time-reversal symmetry at high energies due to chiral edge propagation\nmakes the universal two-terminal conductance of the FQHL fractionally quantized\nand different from that of a 1D Tomonaga-Luttinger liquid wire, where a similar\nmodel but preserving the time-reversal symmetry predicts unsuppressed\nfree-electron conductance.",
        "positive": "Interband optical conductivity of the [001]-oriented Dirac semimetal\n  Cd3As2: We measured the optical reflectivity of [001]-oriented $n$-doped\nCd$_{3}$As$_{2}$ in a broad frequency range (50 - 22000 cm$^{-1}$) for\ntemperatures from 10 to 300 K. The optical conductivity, $\\sigma(\\omega) =\n\\sigma_{1}(\\omega) + {\\rm i}\\sigma_{2}(\\omega)$, is isotropic within the (001)\nplane; its real part follows a power law, $\\sigma_{1}(\\omega) \\propto\n\\omega^{1.65}$, in a large interval from 2000 to 8000 cm$^{-1}$. This behavior\nis caused by interband transitions between two Dirac bands, which are\neffectively described by a sublinear dispersion relation, $E(k) \\propto \\lvert\nk \\rvert ^{0.6}$. The momentum-averaged Fermi velocity of the carriers in these\nbands is energy dependent and ranges from $1.2 \\times 10^{5}$ to $3 \\times\n10^{5}$ m/s, depending on the distance from the Dirac points. We detect a\ngaplike feature in $\\sigma_{1}(\\omega)$ and associate it with the Fermi level\npositioned around $100$ meV above the Dirac points."
    },
    {
        "anchor": "Laser Controlled Spin Dynamics of Ferromagnetic Thin Film from\n  Femtosecond to Nanosecond Timescale: Laser induced modulation of the magnetization dynamics occurring over various\ntime-scales have been unified here for a Ni80Fe20 thin film excited by\namplified femtosecond laser pulses. The weak correlation between\ndemagnetization time and pump fluence with substantial enhancement in\nremagnetization time is demonstrated using three-temperature model considering\nthe temperatures of electron, spin and lattice. The picosecond magnetization\ndynamics is modeled using the Landau-Lifshitz-Gilbert equation. With increasing\npump fluence the Gilbert damping parameter shows significant enhancement from\nits intrinsic value due to increment in the ratio of electronic temperature to\nCurie temperature within very short time scale. The precessional frequency\nexperiences noticeable red shift with increasing pump fluence. The changes in\nthe local magnetic properties due to accumulation and dissipation of thermal\nenergy within the probed volume are described by the evolution of temporal\nchirp parameter in a comprehensive manner. A unification of ultrafast magnetic\nprocesses and its control over broad timescale would enable the integration of\nvarious magnetic processes in a single device and use one effect to control\nanother.",
        "positive": "Proposal for an on-demand source of polarized electrons into the edges\n  of a topological insulator: We propose a device that allows for the emission of pairs of spin-polarized\nelectrons into the edge-states of a two dimensional topological insulator.\nCharge and spin emission is achieved using a periodically driven quantum dot\nweakly coupled to the edge states of the host topological insulator. We present\ncalculations of the emitted time-dependent charge and spin currents of such a\ndynamical scatterer using the Floquet scattering matrix approach. Experimental\nsignatures of spin-polarized two-particle emission can be found in noise\nmeasurements. Here a new form of noise suppression, named\n$\\mathbb{Z}_2$--antibunching, is introduced. Additionally, we propose a set-up\nin which entanglement of the emitted electrons is generated. This entanglement\nis based on a post-selection procedure and becomes manifest in a violation of a\nClauser-Horne-Shimony-Holt inequality."
    },
    {
        "anchor": "Atomic scale visualization of topological spin textures in the chiral\n  magnet MnGe: Spin polarized scanning tunneling microscopy is used to directly image\ntopological magnetic textures in thin films of MnGe, and to correlate the\nmagnetism with structure probed at the atomic-scale. Our images indicate\nhelical stripe domains, each characterized by a single wavevector Q, and their\nassociated helimagnetic domain walls, in contrast to the 3Q magnetic state seen\nin the bulk. Combining our surface measurements with micromagnetic modeling, we\ndeduce the three-dimensional orientation of the helical wavevectors and gain\ndetailed understanding of the structure of individual domain walls and their\nintersections. We find that three helical domains meet in two distinct ways to\nproduce either a \"target-like\" or a \"pi-like\" topological spin texture, and\ncorrelate these with local strain on the surface. We further show that the\ntarget-like texture can be reversibly manipulated through either\ncurrent/voltage pulsing or applied magnetic field, a promising step toward\nfuture applications.",
        "positive": "Broad-band coherent backscattering spectroscopy of the interplay between\n  order and disorder in 3D opal photonic crystals: We present an investigation of coherent backscattering of light that is\nmultiple scattered by a photonic crystal by using a broad-band technique. The\nresults significantly extend on previous backscattering measurements on\nphotonic crystals by simultaneously accessing a large frequency and angular\nrange. Backscatter cones around the stop gap are successfully modelled with\ndiffusion theory for a random medium. Strong variations of the apparent mean\nfree path and the cone enhancement are observed around the stop band. The\nvariations of the mean free path are described by a semi-empirical three-gap\nmodel including band structure effects on the internal reflection and\npenetration depth. A good match between theory and experiment is obtained\nwithout the need of additional contributions of group velocity or density of\nstates. We argue that the cone enhancement reveals additional information on\ndirectional transport properties that are otherwise averaged out in diffuse\nmultiple scattering."
    },
    {
        "anchor": "Persistent currents in ballistic normal-metal rings: Recent experiments renewed interest in persistent currents in mesoscopic\nnormal-metal rings. We show that in ballistic rings in high magnetic fields the\nZeeman splitting leads to periodic current quenching with period much larger\nthan the period of the persistent current. Simple arguments show that this\neffect might be relevant for diffusive rings as well. Another aim of this paper\nis to discuss fluctuations of the persistent current due to thermal excitation\nof high energy levels. Being observed such fluctuations would witness a\ncoherent state of an electron system at high temperatures when the persistent\ncurrent is exponentially suppressed.",
        "positive": "Designing Small Silicon Quantum Dots with Low Reorganization Energy: A first principles, excited state analysis is carried out to identify ways of\nproducing silicon quantum dots with low excitonic reorganization energy. These\nfocus on the general strategy of either reducing or constraining exciton-phonon\ncoupling, and four approaches are explored. The results can be implemented in\nquantum dot solids to mitigate polaronic effects and increase the lifetime of\ncoherent excitonic superpositions. It is demonstrated that such designs can\nalso be used to alter the shape of the spectral density for reorganization so\nas to reduce the rates of both decoherence and dissipation. The results suggest\nthat it may be possible to design quantum dot solids that support partially\ncoherent exciton transport."
    },
    {
        "anchor": "Andreev and Majorana bound states in single and double quantum dot\n  structures: We present a numerical study of the emergence of Majorana and Andreev bound\nstates in a system composed by two quantum dots, in which one of then is\ncoupled to a conventional superconductor, SC1, and the other connects to a\ntopological superconductor, SC2. By controlling the interdot coupling we can\ndrive the system from a two single (uncoupled) quantum dots to a double\n(coupled) dot system configurations. We employ a recursive Green's function\ntechnique that provides us with numerically exact results for the local density\nof states of the system. We first show that in the uncoupled dot configuration\n(single dot behavior) the Majorana and the Andreev bound states appear in an\nindividual dot in two completely distinct regimes. Therefore, they cannot\ncoexist in the single quantum dot system. We then study the coexistence of\nthese states in the coupled double-dot configuration. In this situation we show\nthat in the trivial phase of the SC2, the Andreev states are bound to an\nindividual quantum dot in the atomic regime (weak interdot coupling) or\nextended over the entire molecule in the molecular regime (strong interdot\ncoupling). More interesting features is actually seen in the topological phase\nof the SC2. In this case, in the atomic limit, the Andreev states appear bound\nto one of the quantum dots while a Majorana zero mode appears in the other one.\nIn the molecular regime, on the other hand, the Andreev bound states take over\nthe entire molecule while the Majorana state remains always bound to one of the\nquantum dots.",
        "positive": "Attosecond magnetization dynamics in non-magnetic materials driven by\n  intense femtosecond lasers: Irradiating solids with ultrashort laser pulses is known to initiate\nfemtosecond timescale magnetization dynamics. However, sub-femtosecond spin\ndynamics have not yet been observed or predicted. Here, we explore ultrafast\nlight-driven spin dynamics in a highly non-resonant strong-field regime.\nThrough state-of-the-art ab-initio calculations, we predict that a non-magnetic\nmaterial can be transiently transformed into a magnetic one via dynamical\nextremely nonlinear spin-flipping processes, which occur on attosecond\ntimescales and are mediated by a combination of multi-photon and spin-orbit\ninteractions. These are non-perturbative non-resonant analogues to the inverse\nFaraday effect that build up from cycle-to-cycle as electrons gain angular\nmomentum. Remarkably, we show that even for linearly polarized driving, where\none does not intuitively expect any magnetic response, the magnetization\ntransiently oscillates as the system interacts with light. This oscillating\nresponse is enabled by transverse anomalous light-driven currents in the solid,\nand typically occurs on timescales of ~500 attoseconds. We further demonstrate\nthat the speed of magnetization can be controlled by tuning the laser\nwavelength and intensity. An experimental set-up capable of measuring these\ndynamics through pump-probe transient absorption spectroscopy is outlined and\nsimulated. Our results pave the way for new regimes of ultrafast manipulation\nof magnetism."
    },
    {
        "anchor": "Phase-coherent caloritronics with ordinary and topological Josephson\n  junctions: We provide a brief and comprehensive overview over recent developments in the\nfield of phase-coherent caloritronics in ordinary and topological Josephson\njunctions. We start from the simple case of a short, one-dimensional\nsuperconductor-normal metal-superconductor (S-N-S) Josephson junction and\nderive the phase-dependent thermal conductance within the Bogoliubov-de Gennes\nformalism. Then, we review the key experimental breakthroughs that have\ntriggered the recent growing interest into phase-coherent heat transport. They\ninclude the realization of thermal interferometers, diffractors, modulators and\nrouters based on superconducting tunnel junctions. Finally, we discuss very\nrecent theoretical findings based on superconductor-topological\ninsulator-superconductor (S-TI-S) Josephson junctions that show interesting\nheat transport properties due to the interplay between topological band\nstructures and superconductivity.",
        "positive": "All-optical control of excitons in semiconductor quantum wells: Applying the Floquet theory, we developed the method to control excitonic\nproperties of semiconductor quantum wells by a high-frequency electromagnetic\nfield. It is demonstrated, particularly, that the field induces the blue shift\nof exciton emission from the quantum wells and narrows width of the\ncorresponding spectral line. As a consequence, the field strongly modifies\noptical properties of the quantum wells and, therefore, can be used to tune\ncharacteristics of the optoelectronic devices based on them."
    },
    {
        "anchor": "Ab initio investigation of Elliott-Yafet electron-phonon mechanism in\n  laser-induced ultrafast demagnetization: The spin-flip (SF) Eliashberg function is calculated from first-principles\nfor ferromagnetic Ni to accurately establish the contribution of Elliott-Yafet\nelectron-phonon SF scattering to Ni's femtosecond laser-driven demagnetization.\nThis is used to compute the SF probability and demagnetization rate for\nlaser-created thermalized as well as non-equilibrium electron distributions.\nIncreased SF probabilities are found for thermalized electrons, but the induced\ndemagnetization rate is extremely small. A larger demagnetization rate is\nobtained for {non-equilibrium} electron distributions, but its contribution is\ntoo small to account for femtosecond demagnetization.",
        "positive": "Nanoscale electronic inhomogeneities in 1T-TaS$_2$: We report a set of scanning tunneling microscopy (STM) and spectroscopy (STS)\nexperiments studying native defects in CVT grown 1T-TaS$_2$. Six different\nsample surfaces from four bulk crystals were investigated. Wide area imaging\nreveals a prevalence of nanometer-scale electronic inhomogeneities due to\nnative defects, with pristine regions interspersed. These inhomogeneities\nappear in typical as-grown crystals and coexist with a well-formed commensurate\ncharge density wave of 1T-TaS$_2$ at low temperatures. Electronic\ninhomogeneities show up both as variations in the apparent height in STM and in\nthe local density of states in STS; the bands can shift by 60 meV and the gap\nvaries by more than 100 meV across inhomogeneities. These inhomogeneities are\npresent in similar concentration across large-scale areas of all samples\nstudied, but do not influence the charge density wave formation on local or\nglobal scales. The commensurate charge density wave exhibits long-range order\nand remains locally intact in the presence of these inhomogeneities."
    },
    {
        "anchor": "Singular Pair Breaking in the Composite Fermi Liquid Description of the\n  Half-Filled Landau Level: Fluctuations of the Chern-Simons gauge field in the composite Fermi liquid\ndescription of the half-filled Landau level are pair breaking in all angular\nmomentum channels. For short-range electron-electron interactions these\nfluctuations are sufficiently strong to drive any T=0 pairing transition first\norder. For Coulomb interactions these fluctuations are weaker and a continuous\ntransition is possible.",
        "positive": "Transport properties of a two-dimensional electron liquid at high\n  magnetic field: The chiral Luttinger liquid model for the edge dynamics of a two-dimensional\nelectron gas in a strong magnetic field is derived from coarse-graining and a\nlowest Landau level projection procedure at arbitrary filling factors $\\nu<1$\n-- without reference to the quantum Hall effect. Based on this model, we\ndevelop a formalism to calculate the Landauer-B\\\"uttiker conductances in\ngeneric experimental set-ups including multiple leads and voltage probes. In\nthe absence of tunneling between the edges the \"ideal\" Hall conductances\n($G_{ij}= \\frac{e^2 \\nu}{h}$ if lead $j$ is immediately upstream of lead $i$,\nand $G_{ij}=0$ otherwise) are recovered. Tunneling of quasiparticles of\nfractional charge $e^*$ between different edges is then included as an\nadditional term in the Hamiltonian. In the limit of weak tunneling we obtain\nexplicit expressions for the corrections to the ideal conductances. As an\nillustration of the formalism we compute the current- and temperature-dependent\nresistance $R_{xx}(I,T)$ of a quantum point contact localized at the center of\na gate-induced constriction in a quantum Hall bar. The exponent $\\alpha$ in the\nlow-current relation $R_{xx}(I,0) \\sim I^{\\alpha -2}$ shows a nontrivial\ndependence on the strength of the inter-edge interaction, and its value changes\nas $e^*V_H$, where $V_H = \\frac{h I}{\\nu e^2}$ is the Hall voltage, falls below\na characteristic crossover energy $\\frac{\\hbar c}{d}$, where $c$ is the edge\nwave velocity and $d$ is the length of the constriction. The consequences of\nthis crossover are discussed vis-a-vis recent experiments in the weak tunneling\nregime."
    },
    {
        "anchor": "Optically driven spin pumping mediating collective magnetization\n  dynamics in a spin valve structure: We demonstrate spin pumping, i.e. the generation of a pure spin current by\nprecessing magnetization, without application of microwave radiation commonly\nused in spin pumping experiments. We use femtosecond laser pulses to\nsimultaneously launch the magnetization precession in each of two ferromagnetic\nlayers of a Galfenol-based spin valve and monitor the temporal evolution of the\nmagnetizations. The spin currents generated by the precession cause a dynamic\ncoupling of the two layers. This coupling has dissipative character and is\nespecially efficient when the precession frequencies in the two layers are in\nresonance, where coupled modes with strongly different decay rates are formed.",
        "positive": "Anomalies in the switching dynamics of C-type antiferromagnets and\n  antiferromagnetic nanowires: Antiferromagnets (AFMs) are widely believed to be superior than ferromagnets\nin spintronics because of their high stability due to the vanishingly small\nstray field. It is thus expected that the order parameter of AFM should always\nalign along the easy-axis of the crystalline anisotropy. In contrast to this\nconventional wisdom, we find that the AFM order parameter switches away from\nthe easy-axis below a critical anisotropy strength when an AFM is properly\ntailored into a nano-structure. The switching time first decreases and then\nincreases with the damping. Above the critical anisotropy, the AFM order\nparameter is stable and precesses under a microwave excitation. However, the\nabsorption peak is not at resonance frequency even for magnetic damping as low\nas 0.01. To resolve these anomalies, we first ascertain the hidden role of\ndipolar interaction that reconstructs the energy landscape of the nano-system\nand propose a model of damped non-linear pendulum to explain the switching\nbehavior. In this framework, the second anomaly appears when an AFM is close to\nthe boundary between underdamped and overdamped phases, where the observed\nabsorption lineshape has small quality factor and thus is not reliable any\nlonger. Our results should be significant to extract the magnetic parameters\nthrough resonance techniques."
    },
    {
        "anchor": "Bias-induced breakdown of electron solids in the second Landau level: Reentrant integer quantum Hall (RIQH) states are believed to be correlated\nelectron solid phases, though their microscopic description remains unclear. As\nbias current increases, longitudinal and Hall resistivities measured for these\nstates exhibit multiple sharp breakdown transitions, a signature unique to RIQH\nstates. A comparison of RIQH breakdown characteristics at multiple voltage\nprobes indicates that these signatures can be ascribed to a phase boundary\nbetween broken-down and unbroken regions, spreading chirally from source and\ndrain contacts as a function of bias current and passing voltage probes one by\none. The chiral sense of the spreading is not set by the chirality of the edge\nstate itself, instead depending on electron- or hole-like character of the RIQH\nstate.",
        "positive": "Luttinger Parameter g for Metallic Carbon Nanotubes and Related Systems: The random phase approximation (RPA) theory is used to derive the Luttinger\nparameter g for metallic carbon nanotubes. The results are consistent with the\nTomonaga-Luttinger models. All metallic carbon nanotubes, regardless if they\nare armchair tubes, zigzag tubes, or chiral tubes, should have the same\nLuttinger parameter g. However, a (10,10) carbon peapod should have a smaller g\nvalue than a (10,10) carbon nanotube. Changing the Fermi level by applying a\ngate voltage has only a second order effect on the g value. RPA theory is a\nvalid approach to calculate plasmon energy in carbon nanotube systems,\nregardless if the ground state is a Luttinger liquid or Fermi liquid. (This\npaper was published in PRB 66, 193405 (2002). However, Eqs. (6), (9), and (19)\nwere misprinted there.)"
    },
    {
        "anchor": "Voltage-time dilemma and stochastic threshold voltage variation in pure\n  silver atomic switches: The formation and dissolution of silver nanowires plays a fundamental role in\na broad range of resistive switching devices, fundamentally relying on the\nelectrochemical metallization phenomenon. It was shown, however, that resistive\nswitching may also appear in pure metallic nanowires lacking any\nsilver-ion-hosting embedding environment, but this pure atomic switching\nmechanism fundamentally differs from the conventional\nelectrochemical-metallization-based resistive switching. To facilitate the\nquantitative description of the former phenomenon, we investigate broad range\nof Ag atomic junctions with a special focus on the frequency-dependence and the\nfundamentally stochastic cycle-to-cycle variation of the switching threshold\nvoltage. These devices are established in an ultra-high purity environment\nwhere electrochemical metallization can be excluded. The measured\ncharacteristics are successfully described by a vibrational pumping model,\nyielding consistent predictions for the weak frequency dependence and the large\nvariance of the switching threshold voltage. We also demonstrate that\nelectrochemical-metallization-based resistive switching and pure atomic\nswitching may appear in the same device structure, and therefore the proper\nunderstanding of the pure atomic switching mechanism has a distinguished\nimportance in silver-based electrochemical metallization cells.",
        "positive": "Insights on magnon topology and valley-polarization in 2D bilayer\n  quantum magnets: The rich and unconventional physics in layered 2D magnets can open new\navenues for topological magnonics and magnon valleytronics. In particular,\ntwo-dimensional (2D) bilayer quantum magnets are gaining increasing attention\ndue to their intriguing stacking-dependent magnetism, controllable ground\nstates, and topological excitations induced by magnetic spin-orbit couplings\n(SOCs). Despite the substantial research on these materials, their topological\nfeatures remain widely unexplored to date. The present study comprehensively\ninvestigates the magnon topology and magnon valley-polarization in honeycomb\nbilayers with collinear magnetic order. We elucidate the separate and combined\neffects of the SOC, magnetic ground-states, stacking order, and inversion\nsymmetry breaking on the topological phases, magnon valley transport, and the\nHall and Nernst effects. The comprehensive analysis suggests clues to determine\nthe SOC's nature and predicts unconventional Hall and Nernst conductivities in\ntopologically trivial phases. We further report on novel bandgap closures in\nlayered antiferromagnets and detail their topological implications. We believe\nthe present study provides important insights into the fundamental physics and\ntechnological potentials of topological 2D magnons."
    },
    {
        "anchor": "Images of edge current in InAs/GaSb quantum wells: Quantum spin Hall devices with edges much longer than several microns do not\ndisplay ballistic transport: that is, their measured conductances are much less\nthan $e^2/h$ per edge. We imaged edge currents in InAs/GaSb quantum wells with\nlong edges and determined an effective edge resistance. Surprisingly, although\nthe effective edge resistance is much greater than $h/e^2$, it is independent\nof temperature up to 30 K within experimental resolution. Known candidate\nscattering mechanisms do not explain our observation of an effective edge\nresistance that is large yet temperature-independent.",
        "positive": "Electron Transport in Magnetic-Field-Induced Quasi-One-Dimensional\n  Electron Systems in Semiconductor Nanowhiskers: Many-body effects on tunneling of electrons in semiconductor nanowhiskers are\ninvestigated in a magnetic quantum limit. We consider the system with which\nbulk and edge states coexist. We show that interaction parameters of edge\nstates are much smaller than those of bulk states and the tunneling conductance\nof edge states hardly depends on temperature and the singular behavior of\ntunneling conductance of bulk states can be observed."
    },
    {
        "anchor": "Characterization of low-temperature microwave loss of thin aluminum\n  oxide formed by plasma oxidation: We report on the characterization of microwave loss of thin aluminum oxide\nfilms at low temperatures using superconducting lumped resonators. The oxide\nfilms are fabricated using plasma oxidation of aluminum and have a thickness of\n5 nm. We measure the dielectric loss versus microwave power for resonators with\nfrequencies in the GHz range at temperatures from 54 to 303 mK. The power and\ntemperature dependence of the loss is consistent with the tunneling two-level\nsystem theory. These results are relevant to understanding decoherence in\nsuperconducting quantum devices. The obtained oxide films are thin and robust,\nmaking them suitable for capacitors in compact microwave resonators.",
        "positive": "AC conductivity of graphene: from tight-binding model to 2+1-dimensional\n  quantum electrodynamics: We consider the relationship between the tight-binding Hamiltonian of the\ntwo-dimensional honeycomb lattice of carbon atoms with nearest neighbor hopping\nonly and the 2+1 dimensional Hamiltonian of quantum electrodynamics which\nfollows in the continuum limit. We pay particular attention to the symmetries\nof the free Dirac fermions including spatial inversion, time reversal, charge\nconjugation and chirality. We illustrate the power of such a mapping by\nconsidering the effect of the possible symmetry breaking which corresponds to\nthe creation of a finite Dirac mass, on various optical properties. In\nparticular, we consider the diagonal AC conductivity with emphasis on how the\nfinite Dirac mass might manifest itself in experiment. The optical sum rules\nfor the diagonal and Hall conductivities are discussed."
    },
    {
        "anchor": "Mode conversion by symmetry breaking of propagating spin waves: We study spin-wave transport in a microstructured Ni81Fe19 waveguide\nexhibiting broken translational symmetry. We observe the conversion of a beam\nprofile composed of symmetric spin-wave width modes with odd numbers of\nantinodes n=1,3,... into a mixed set of symmetric and asymmetric modes. Due to\nthe spatial homogeneity of the exciting field along the used microstrip\nantenna, quantized spin-wave modes with an even number n of antinodes across\nthe stripe's width cannot be directly excited. We show that a break in\ntranslational symmetry may result in a partial conversion of even spin-wave\nwaveguide modes",
        "positive": "A Molecular Platinum Cluster Junction: A Single-Molecule Switch: We present a theoretical study of the electronic transport through\nsingle-molecule junctions incorporating a Pt6 metal cluster bound within an\norganic framework. We show that the insertion of this molecule between a pair\nof electrodes leads to a fully atomically engineered nano-metallic device with\nhigh conductance at the Fermi level and two sequential high on/off switching\nstates. The origin of this property can be traced back to the existence of a\nHOMO which consists of two degenerate and asymmetric orbitals, lying close in\nenergy to the Fermi level of the metallic leads. Their degeneracy is broken\nwhen the molecule is contacted to the leads, giving rise to two resonances\nwhich become pinned close to the Fermi level and display destructive\ninterference."
    },
    {
        "anchor": "Theory of Spin Transport Across Domain-Walls in (Ga,Mn)As: We present results of numerical calculations of domain-wall resistance in the\nferromagnetic semiconductor (Ga,Mn)As. We employ Landauer-Buttiker formalism\nand the tight binding method. Taking into account the full valence band\nstructure we predict the magnitude of the domain-wall resistance without\ndisorder and compare it to experimental values. Next we add disorder to the\nmodel and study numerically both small and large disorder regime.",
        "positive": "Improved in-situ characterization of electrochemical interfaces using\n  metasurface-driven surface-enhanced infrared absorption spectroscopy: Electrocatalysis plays a crucial role in realizing the transition towards\ngreen energy, driving research directions from hydrogen generation to carbon\ndioxide reduction. Understanding electrochemical reactions is crucial to\nimprove their efficiency and to bridge the gap toward a sustainable zero-carbon\nfuture. Surface-enhanced infrared absorption spectroscopy (SEIRAS) is a\nsuitable method for investigating these processes because it can monitor with\nchemical specificity the mechanisms of the reactions. However, it remains\ndifficult to detect many relevant aspects of electrochemical reactions such as\nshort-lived intermediates. Here, we develop and experimentally realize an\nintegrated nanophotonic-electrochemical SEIRAS platform for the in situ\ninvestigation of molecular signal traces emerging during electrochemical\nexperiments. Specifically, we implement a platinum nano-slot metasurface\nfeaturing strongly enhanced electromagnetic near fields and spectrally target\nit at the weak vibrational bending mode of adsorbed CO at ~2033 cm-1.\nCrucially, our platinum nano-slot metasurface provides high molecular\nsensitivity. The resonances can be tuned over a broad range in the mid-infrared\nspectrum. Compared to conventional unstructured platinum layers, our\nnanophotonic-electrochemical platform delivers a substantial improvement of the\nexperimentally detected characteristic absorption signals by a factor of 27,\nenabling the detection of new species with weak signals, fast conversions, or\nlow surface concentrations. By providing a deeper understanding of catalytic\nreactions, we anticipate our nanophotonic-electrochemical platform to open\nexciting perspectives for electrochemical SEIRAS, surface-enhanced Raman\nspectroscopy, and the study of reactions in other fields of chemistry such as\nphotoelectrocatalysis."
    },
    {
        "anchor": "Conductivity of interacting massless Dirac particles in graphene:\n  Collisionless regime: We provide detailed calculation of the a.c. conductivity in the case of\n1/r-Coulomb interacting massless Dirac particles in graphene in the\ncollisionless limit when \\omega >> T. The analysis of the electron self-energy,\ncurrent vertex function and polarization function, which enter into the\ncalculation of physical quantities including the a.c. conductivity, is carried\nout by checking the Ward-Takahashi identities associated with the electrical\ncharge conservation and making sure that they are satisfied at each step. We\nadopt a variant of the dimensional regularization of Veltman and t'Hooft by\ntaking the spatial dimension D=2-\\epsilon, for \\epsilon > 0. The procedure\nadopted here yields a result for the conductivity correction which, while\nexplicitly preserving charge conservation laws, is nevertheless different from\nthe results reported previously in literature.",
        "positive": "Analytic understanding and control of dynamical friction: Recent model simulations discovered unexpected non-monotonic features in the\nwear-free dry phononic friction as a function of the sliding speed. Here we\ndemonstrate that a rather straight- forward application of linear-response\ntheory, appropriate in a regime of weak slider-substrate in- teraction,\npredicts frictional one-phonon singularities which imply a non-trivial\ndependence of the dynamical friction force on the slider speed and/or coupling\nto the substrate. The explicit formula which we derive reproduces very\naccurately the classical atomistic simulations when available. By modifying the\nslider-substrate interaction the analytical understanding obtained provides a\npractical means to tailor and control the speed dependence of friction with\nsubstantial freedom."
    },
    {
        "anchor": "Renormalization of the Coulomb blockade gap due to extended tunneling in\n  nanoscopic junctions: In this work we discuss the combined effects of finite-range\nelectron-electron interaction and finite-range tunneling on the transport\nproperties of ultrasmall tunnel junctions. We show that the Coulomb blockade\nphenomenon is deeply influenced by the interplay between the geometry and the\nscreening properties of the contacts. In particular if the interaction range is\nsmaller than the size of the tunneling region a \"weakly correlated\" regime\nemerges in which the Coulomb blockade gap $\\D$ is significantly reduced. In\nthis regime $\\D$ is not simply given by the conventional charging energy of the\njunction, since it is strongly renormalized by the energy that electrons need\nto tunnel over the extended contact.",
        "positive": "Thermodynamics of energy, charge and spin currents in thermoelectric\n  quantum-dot spin valve: We provide a thermodynamically consistent description of energy, charge and\nspin transfers in a thermoelectric quantum-dot spin valve in the collinear\nconfiguration based on nonequilibrium Green's function and full counting\nstatistics. We use the fluctuation theorem symmetry and the concept of entropy\nproduction to characterize the efficiency with which thermal gradients can\ntransduce charges or spins against their chemical potentials, arbitrary far\nfrom equilibrium. Close to equilibrium, we recover the Onsager reciprocal\nrelations and the connection to linear response notions of performance such as\nthe figure of merit. We also identify regimes where work extraction is more\nefficient far then close from equilibrium."
    },
    {
        "anchor": "Chern band insulators in magnetic field: The effect of a magnetic field on a two-dimensional Chern band insulator is\ndiscussed. It is shown that, unlike the trivial insulator, an anomalous Hall\ninsulator with Chern number $C$ becomes a metal when a magnetic field is\napplied at constant particle density, for any $C>0$. For a time reversal\ninvariant topological insulator with a spin Chern resolved number, $C_\\uparrow=\n- C_\\downarrow=C$, the magnetic field induces a spin polarized spin Hall\ninsulator. We consider also the effect of a superlattice potential and extend\nprevious results for the quantization of the Hall conductance of filled\nHofstadter bands to this problem.",
        "positive": "Magnetic response of metallic nanoparticles: Geometric and weakly\n  relativistic effects: While the large paramagnetic response measured in certain ensembles of\nmetallic nanoparticles has been assigned to orbital effects of conduction\nelectrons, the spin-orbit coupling has been pointed out as a possible origin of\nthe anomalously large diamagnetic response observed in other cases. Such a\nrelativistic effect, arising from the inhomogeneous electrostatic potential\nseen by the conduction electrons, might originate from the host ionic lattice,\nimpurities, or the self-consistent confining potential. Here we theoretically\ninvestigate the effect of the spin-orbit coupling arising from the confining\npotential, quantifying its contribution to the zero-field magnetic\nsusceptibility and gauging it against the ones generated by other\nweakly-relativistic corrections. Two ideal geometries are considered in detail,\nthe sphere and the half-sphere, focusing on the expected increased role of the\nspin-orbit coupling upon a symmetry reduction, and the application of these\nresults to actual metallic nanoparticles is discussed. The matrix elements of\nthe different weakly-relativistic corrections are obtained and incorporated in\na perturbative treatment of the magnetic field, leading to tractable\nsemi-analytical and semiclassical expressions for the case of the sphere, while\na numerical treatment becomes necessary for the half-sphere. The correction to\nthe zero-field susceptibility arising from the spin-orbit coupling in a single\nsphere is quite small, and it is dominated by the weakly-relativistic kinetic\nenergy correction, which in turn remains considerably smaller than the typical\nvalues of the nonrelativistic zero-field susceptibility. Moreover, the\nspin-orbit contribution to the average response for ensembles of nanoparticles\nwith a large size dispersion is shown to vanish. The symmetry reduction in\ngoing from the single sphere to the half-sphere does not translate into a\nsignificant (...)"
    },
    {
        "anchor": "Dipolar spin relaxation of divacancy qubits in silicon carbide: Divacancy spins in silicon carbide implement qubits with outstanding\ncharacteristics and capabilities in an industrial semiconductor host. On the\nother hand, there are still numerous open questions about the physics of\ndivacancy point defects, for instance, spin relaxation has not been thoroughly\nstudied yet. Here, we carry out a theoretical study on environmental spin\ninduced spin relaxation processes of divacancy qubits in 4H-SiC. We reveal all\nthe relevant magnetic field values where the longitudinal spin relaxation time\nT$_1$ drops resonantly due to the coupling to either nuclear spins or electron\nspins. We quantitatively analyze the dependence of the T$_1$ time on the\nconcentration of point defect spins and the applied magnetic field in the most\nrelevant cases and provide an analytical expression. We demonstrate that\ndipolar spin relaxation plays a significant role both in as-grown and ion\nimplanted samples and it often limits the coherence time in 4H-SiC.",
        "positive": "Hydrogenation Dynamics of Twisted Carbon Nanotubes: Carbon Nanotubes (CNTs) are one of the most important materials in\nnanotechnology. In some of their technological applications (electromechanical\noscillators and mechanical actuators for artificial muscles, for instance), it\nis necessary to subject them to large deformations. Although this frequently\nhappens in air, there are only few studies about the interaction of deformed\nCNTs with the atmosphere and the dynamics of these processes has not yet been\naddressed. In this work, we have investigated, through fully atomistic reactive\nmolecular dynamics simulations, the process of hydrogenation of highly twisted\nCNTs. Our results show that hydrogenation effective ratio is directly related\nto the tube twist angle values and can lead to twisted tube fractures with well\ndefined patterns (unzip-like). Our results also show that these fracture\nprocesses can be exploited to controllably produce graphene nanoribbons."
    },
    {
        "anchor": "Electrical conductivity and screening effect of spin-1 chiral fermions\n  scattered by charged impurities: We theoretically study the quantum transport in a three-dimensional spin-1\nchiral fermion system in the presence of coulomb impurities based on the\nself-consistent Born approximation. We find that the flat-band states\nanomalously enhance the screening effect, and the electrical conductivity is\nincreased in the low-energy region. It is also found that reducing the\nscreening length leads to an increase in the forward scattering contribution\nand, thus, an increase in the vertex correction in the high-energy region.",
        "positive": "Anti-chiral edge states in an exciton polariton strip: We present a scheme to obtain anti-chiral edge states in an exciton-polariton\nhoneycomb lattice with strip geometry, where the modes corresponding to both\nedges propagate in the same direction. Under resonant pumping the effect of a\npolariton condensate with nonzero velocity in one linear polarization is\npredicted to tilt the dispersion of polaritons in the other, which results in\nan energy shift between two Dirac cones and the otherwise flat edge states\nbecome tilted. Our simulations show that due to the spatial separation from the\nbulk modes the edge modes are robust against disorder."
    },
    {
        "anchor": "Magnetism on the thermal dynamics of 2D antiferromagnetic membranes: We developed a theoretical scheme of incorporating the magnetoelastic\ncontribution into the thermal elastic dynamics for the thin membranes of 2D\nantiferromagnetic material with restricted geometry. We extended the elastic\nGr\\\"uneisen relation into an effective version which includes the magnetic\ncounterpart to the volume change of internal energy. Based on the specific heat\nand thermal conductivity from the elastic and magnetic origins we predicted the\ndependency of observables, such as effective Gr\\\"uneisen parameter, thermal\nexpansion coefficient, and the damping factor, with respect to a wide range of\ntemperature across the phase transition. Our model of analysis as been\nvalidated by applying to the case of FePS3 flake resonator and the theoretical\npredictions fits well with the reported experiment data.",
        "positive": "Quantum Error Correction for Complex and Majorana Fermion Qubits: We introduce error-correcting codes that can correct for fermion\nparity-violating (quasiparticle poisoning) and parity-conserving errors in\nsystems of complex fermions and of Majorana fermions. After establishing\nproperties of fermion codes, we introduce a generic construction of fermion\ncodes from weakly self-dual classical, binary error-correcting codes. We use\nthis method to construct (i) the shortest fermion code to correct for\nquasiparticle poisoning errors, (ii) translationally-invariant fermion codes\nand (iii) other codes that correct higher-weight errors. We conclude by\ndiscussing a possible physical realizations of one such code in mesoscopic\nsuperconductors hosting Majorana zero modes."
    },
    {
        "anchor": "Energy barriers of Be and B in passing through the C60 fullerene cage: We have studied the potential barriers for the penetration of atomic\nberyllium or boron inside the C60 fullerene by performing ab initio density\nfunctional theory (DFT) calculations with three variants for the exchange and\ncorrelation: B3LYP (hybrid functional), PW91 and PBE. Four principal\ntrajectories to the inner part of C60 for the penetrating atom have been\nconsidered: through the center of six-member-carbon ring (hexagon),\nfive-member-carbon ring (pentagon), and also through the center of the double\nC-C bond (D-bond) and the center of the single C-C bond (S-bond). Averaging\nover the three DFT variants yields the following barriers for beryllium\npenetrating inside a deformable fullerene: 3.2 eV (hexagon), 4.8 eV (S-bond),\n5.3 eV (D-bond), 5.9~eV (pentagon). These barriers correspond to the slow and\nadiabatic penetration of Be, in contrast to the fast (non-adiabatic)\npenetration through the rigid cage of C60 resulting in 5.6 eV (hexagon), 16.3\neV (pentagon), 81.8 eV (S-bond) and 93.4 eV (D-bond). The potential barriers\nfor the boron penetrating inside deformable/rigid C60 are: 3.7/105.4 eV\n(D-bond), 4.0/86.8 eV (S-bond), 4.7/7.8 eV (hexagon), 6.8/14.0 eV (pentagon).\nThe potential barriers for Be and B escaping from the inner part of C$_{60}$\nare higher by the value of 0.84 eV for Be and 0.81 eV for B. The considerable\nreduction of the potential barriers for the deformable fullerene is ascribed to\nthe formation of the Be-C and B-C bonds. We discuss the difference between Be\nand B, compare three variants of DFT, and analyze the role of the dispersion\ninteraction.",
        "positive": "Theory of charge sensing in quantum-dot structures: Charge sensing in quantum-dot structures is studied by an exactly solvable\nreduced model and numerical density-matrix renormalization group methods.\nCharge sensing is characterized by the repeated cycling of the occupation of\ncurrent-carrying states due to the capacitive coupling to trap states which are\nweakly coupled to the leads. In agreement with recent experiments, it results\nin a variety of characteristic behaviors ranging from asymmetric\nCoulomb-blockade peaks to sawtooth- and dome-like structures. Temperature\nintroduces distinct asymmetric smearing of these features and correlations in\nthe conductance provide a fingerprint of charge-sensing behavior."
    },
    {
        "anchor": "Multi-orbital tight binding model for cavity-polariton lattices: In this work we present a tight-binding model that allows to describe with a\nminimal amount of parameters the band structure of exciton-polariton lattices.\nThis model based on $s$ and $p$ non-orthogonal photonic orbitals faithfully\nreproduces experimental results reported for polariton graphene ribbons. We\nanalyze in particular the influence of the non-orthogonality, the\ninter-orbitals interaction and the photonic spin-orbit coupling on the\npolarization and dispersion of bulk bands and edge states.",
        "positive": "Controlled assembly of graphene sheets and nanotubes: fabrication of\n  suspended multi-element all-carbon vibrational structures: We report on the fabrication and operation of a multi-element vibrational\nstructure consisting of two graphene mechanical resonators coupled by a\nnanotube beam. The whole structure is suspended. Each graphene resonator is\nclamped by two metal electrodes. The structure is fabricated using a\ncombination of electron-beam lithography and atomic-force microscopy\nnano-manipulation. This layout allows us to detect the mechanical vibrations\nelectrically. The measured eigenmodes are localized in either one of the\ngraphene resonators. The coupling due to the nanotube is studied by measuring\nthe shift of the resonance frequency of one graphene resonator as a function of\nthe vibration amplitude of the other resonator. Coupled graphene resonators\nhold promise for the study of nonlinear dynamics, the manipulation of\nmechanical states, and quantum non-demolition measurements."
    },
    {
        "anchor": "Effects of variable anisotropic-strain on the emission of neutral\n  excitons confined in epitaxial quantum dots: We study the effect of elastic anisotropic biaxial strain on the light\nemitted by neutral excitons confined in different kinds of semiconductor\nquantum dots (QDs). We find that the light polarization rotates by up to 80\ndegree and the excitonic fine structure splitting varies by several tens of\n$\\mu$eVs as the strain is varied. By means of a continuum model we mainly\nascribe the observed effects to substantial changes of the hole wave function.\nThese results show that strain-fields of a few permill magnitude are suffcient\nto dramatically modify the electronic structure of QDs.",
        "positive": "Ballistic transport of long wavelength phonons and thermal conductivity\n  accumulation in nanograined silicon-germanium alloys: Computationally efficient modeling of the thermal conductivity of materials\nis crucial to thorough experimental planning and theoretical understanding of\nthermal properties. We present a modeling approach in this work that utilizes\nfrequency-dependent effective medium to calculate lattice thermal conductivity\nof nanostructured solids. The method accurately predicts a significant\nreduction in the thermal conductivity of nanostructured Si80Ge20 systems, along\nwith previous reported thermal conductivities in nanowires and\nnanoparticles-in-matrix materials. We use our model to gain insight into the\nrole of long wavelength phonons on the thermal conductivity of nanograined\nsilicon-germanium alloys. Through thermal conductivity accumulation\ncalculations with our modified effective medium model, we show that phonons\nwith wavelengths much greater than the average grain size will not be impacted\nby grain boundary scattering, counter to the traditionally assumed notion that\ngrain boundaries in solids will act as diffusive interfaces that will limit\nlong wavelength phonon transport. This is further supported through a\nmodulation frequency dependent thermal conductivity as measured with\ntime-domain thermoreflectance."
    },
    {
        "anchor": "Interplay between nonlinear spectral shift and nonlinear damping of spin\n  waves in ultrathin YIG waveguides: We use the phase-resolved imaging to directly study the nonlinear\nmodification of the wavelength of spin waves propagating in 100-nm thick,\nin-plane magnetized YIG waveguides. We show that, by using moderate microwave\npowers, one can realize spin waves with large amplitudes corresponding to\nprecession angles in excess of 10 degrees and nonlinear wavelength variation of\nup to 18 percent in this system. We also find that, at large precession angles,\nthe propagation of spin waves is strongly affected by the onset of nonlinear\ndamping, which results in a strong spatial dependence of the wavelength. This\neffect leads to a spatially dependent controllability of the wavelength by the\nmicrowave power. Furthermore, it leads to the saturation of nonlinear spectral\nshift's effects several micrometers away from the excitation point. These\nfindings are important for the development of nonlinear, integrated spin-wave\nsignal processing devices and can be used to optimize their characteristics.",
        "positive": "New polarization rotation and exact TEM wave solutions in topological\n  insulators: In the context of $\\theta$ electrodynamics we find transverse electromagnetic\nwave solutions forbidden in Maxwell electrodynamics. Our results attest to new\nevidence of the topological magnetoelectric effect in topological insulators,\nresulting from a polarization rotation of an external electromagnetic field.\nUnlike Faraday and Kerr rotations, the effect does not rely on a longitudinal\nmagnetic field, the reflected field, or birefringence. The rotation occurs due\nto transversal discontinuities of the topological magnetoelectric parameter in\ncylindrical geometries. The dispersion relation is linear, and birefringence is\nabsent. One solution behaves as an optical fiber confining exact transverse\nelectromagnetic fields with omnidirectional reflectivity. These results may\nopen new possibilities in optics and photonics by utilizing topological\ninsulators to manipulate light."
    },
    {
        "anchor": "Dirac point metamorphosis from third-neighbor couplings in graphene: We study the band structure and the density of states of graphene in the\npresence of a next-to-nearest-neighbor coupling (N2) and a\nthird-nearest-neighbor coupling (N3). We show that for values of N3 larger or\nequal to 1/3 of the value of the nearest-neighbor hopping (NN), extra Dirac\npoints appear in the spectrum. If N3 is exactly equal to 1/3 NN, the new Dirac\npoints are localized at the M points of the Brillouin zone and are hybrid: the\nelectrons have a linear dispersion along the GammaM direction and a quadratic\ndispersion along the perpendicular direction MK. For larger values of N3 the\nnew points have a linear dispersion, and are situated along the MK line. For a\nvalue of N3 equal to 1/2 NN, these points merge with the Dirac cones at the K\npoints, yielding a gapless quadratic dispersion around K, while for larger\nvalues each quadratic point at K splits again into four Dirac points. The\neffects of changing the N2 coupling are not so dramatic. We calculate the\ndensity of states and we show that increasing the N3 coupling lowers the energy\nof the Van Hove singularities, and when N3 is larger than 1/3 NN the Van Hove\nsingularities split in two, giving rise to extra singularities at low energies.",
        "positive": "Colossal non-saturating linear magnetoresistance in two-dimensional\n  electron systems at a GaAs/AlGaAs heterointerface: Engineering devices with a large electrical response to magnetic field is of\nfundamental importance for a range of applications such as magnetic field\nsensing and magnetic read-heads. We show that a colossal non-saturating linear\nmagnetoresistance (NLMR) arises in two-dimensional electron systems hosted in a\nGaAs/AlGaAs heterostructure in the strongly insulating regime. When operated at\nhigh source-drain bias, the magnetoresistance of our devices increases almost\nlinearly with magnetic field reaching nearly 10,000% at 8 Tesla, thus\nsurpassing many known non-magnetic materials that exhibit giant NLMR. The\ntemperature dependence and mobility analysis indicate that the NLMR has a\npurely classical origin, driven by nanoscale inhomogeneities. A large NLMR\ncombined with small device dimensions makes these systems a new and attractive\ncandidate for on-chip magnetic field sensing."
    },
    {
        "anchor": "Excitonic Effects in the Optical Spectra of Graphene Nanoribbons: We present a first-principles calculation of the optical properties of\narmchair-edged graphene nanoribbons (AGNRs) with many-electron effects\nincluded. The reduced dimensionality of the AGNRs gives rise to an enhanced\nelectron-hole binding energy for both bright and dark exciton states (0.8-1.4\neV for GNRs with width w ~ 1.2 nm) and dramatically changes the optical spectra\nowing to a near complete transfer of oscillator strength to the exciton states\nfrom the continuum transitions. The characteristics of the excitons of the\nthree distinct families of AGNRs are compared and discussed. The enhanced\nexcitonic effects found here are expected to be of importance in optoelectronic\napplications of graphene-based nanostructures.",
        "positive": "Unexpectedly High Cross-plane Thermoelectric Performance in Layered\n  Carbon Nitrides: Organic thermoelectric (TE) materials create a brand new perspective to\nsearch for high-efficiency TE materials, due to their small thermal\nconductivity. The overlap of pz orbitals, commonly existing in organic\n{\\pi}-stacking semiconductors, can potentially result in high electronic\nmobility comparable to inorganic electronics. Here we propose a strategy to\nutilize the overlap of pz orbitals to increase the TE efficiency of layered\npolymeric carbon nitride (PCN). Through first-principles calculations and\nclassical molecular dynamics simulations, we find that A-A stacked PCN has\nunexpectedly high cross-plane ZT up to 0.52 at 300 K, which can contribute to\nn-type TE groups. The high ZT originates from its one-dimensional charge\ntransport and small thermal conductivity. The thermal contribution of the\noverlap of pz orbitals is investigated, which noticeably enhances the thermal\ntransport when compared with the thermal conductivity without considering the\noverlap effect. For a better understanding of its TE advantages, we find that\nthe low-dimensional charge transport results from strong pz-overlap\ninteractions and the in-plane electronic confinement, by comparing\n{\\pi}-stacking carbon nitride derivatives and graphite. This study can provide\na guidance to search for high cross-plane TE performance in layered materials."
    },
    {
        "anchor": "Spin Seebeck Effect near the Antiferromagnetic Spin-Flop Transition: We develop a low-temperature, long-wavelength theory for the interfacial spin\nSeebeck effect (SSE) in easy-axis antiferromagnets. The field-induced spin-flop\n(SF) transition of N\\'eel order is associated with a qualitative change in SSE\nbehavior: Below SF, there are two spin carriers with opposite magnetic moments,\nwith the carriers polarized along the field forming a majority magnon band.\nAbove SF, the low-energy, ferromagnetic-like mode has magnetic moment opposite\nthe field. This results in a sign change of the SSE across SF, which agrees\nwith recent measurements on Cr$_2$O$_3$/Pt and Cr$_2$O$_3$/Ta devices [Li\n$\\textit{et al.,}$ $\\textit{Nature}$ $\\textbf{578,}$ 70 (2020)]. In our theory,\nSSE is due to a N\\'eel spin current below SF and a magnetic spin current above\nSF. Using the ratio of the associated N\\'eel to magnetic spin-mixing\nconductances as a single constant fitting parameter, we reproduce the field\ndependence of the experimental data and partially the temperature dependence of\nthe relative SSE jump across SF.",
        "positive": "Boltzmann approach to the longitudinal spin Seebeck effect: We develop a Boltzmann transport theory of coupled magnon-phonon transport in\nferromagnetic insulators. The explicit treatment of the magnon-phonon coupling\nwithin the Boltzmann approach allows us to calculate the low-temperature\nmagnetic-field dependence of the spin-Seebeck voltage. Within the Boltzmann\ntheory we find that this magnetic field dependence shows similar features as\nfound by Flebus et al. [Phys. Rev. B 95, 144420 (2017)] for a strongly coupled\nmagnon phonon system that forms magnon-polarons, and consistent with\nexperimental findings in yttrium iron garnet by Kikkawa et al. [Phys. Rev.\nLett. 117, 207203 (2016)]. In addition to the anomalous magnetic-field\ndependence of the spin Seebeck effect, we also predict a dependence on the\nsystem size."
    },
    {
        "anchor": "Electric signature of magnetic domain-wall dynamics: We study current-induced domain-wall dynamics in a thin ferromagnetic\nnanowire. The domain-wall dynamics is described by simple equations with four\nparameters. We propose the procedure to determine these parameters by\nall-electric measurements of the time-dependent voltage induced by the\ndomain-wall motion. We provide an analytical expression for the time variation\nof this voltage. Furthermore, we show that the measurement of the proposed\neffects is within reach with current experimental techniques.",
        "positive": "The visibility of IQHE at sharp edges: Experimental proposals based on\n  interactions and edge electrostatics: The influence of the incompressible strips on the integer quantized Hall\neffect (IQHE) is investigated, considering a cleaved-edge overgrown (CEO)\nsample as an experimentally realizable sharp edge system. We propose a set of\nexperiments to clarify the distinction between the large-sample limit when bulk\ndisorder defines the IQHE plateau width and the small-sample limit smaller than\nthe disorder correlation length, when self-consistent edge electrostatics\ndefine the IQHE plateau width. The large-sample or bulk QH regime is described\nby the usual localization picture, whereas the small-sample or edge regime is\ndiscussed within the compressible/incompressible strips picture, known as the\nscreening theory of QH edges. Utilizing the unusually sharp edge profiles of\nthe CEO samples, a Hall bar design is proposed to manipulate the edge potential\nprofile from smooth to extremely sharp. By making use of a side-gate\nperpendicular to the two dimensional electron system, it is shown that the\nplateau widths can be changed or even eliminated altogether. Hence, the\nvisibility of IQHE is strongly influenced when adjusting the edge potential\nprofile and/or changing the dc current direction under high currents in the\nnon-linear transport regime. As a second investigation, we consider two\ndifferent types of ohmic contacts, namely highly transmitting (ideal) and\nhighly reflecting (non-ideal) contacts. We show that if the injection contacts\nare non-ideal, however still ohmic, it is possible to measure directly the\nnon-quantized transport taking place at the bulk of the CEO samples. The\nresults of the experiments we propose will clarify the influence of the edge\npotential profile and the quality of the contacts, under quantized Hall\nconditions."
    },
    {
        "anchor": "Observation of anomalous Hanle spin precession lineshapes resulting from\n  interaction with localized states: It has been shown recently that in spin precession experiments, the\ninteraction of spins with localized states can change the response to a\nmagnetic field, leading to a modified, effective spin relaxation time and\nprecession frequency. Here, we show that also the shape of the Hanle curve can\nchange, so that it cannot be fitted with the solutions of the conventional\nBloch equation. We present experimental data that shows such an effect arising\nat low temperatures in epitaxial graphene on silicon carbide with localized\nstates in the carbon buffer layer. We compare the strength of the effect\nbetween materials with different growth methods, epitaxial growth by\nsublimation and by chemical vapor deposition. The presented analysis gives\ninformation about the density of localized states and their coupling to the\ngraphene states, which is inaccessible by charge transport measurements and can\nbe applied to any spin transport channel that is coupled to localized states.",
        "positive": "Semi-inverse method in nonlinear mechanics: application to couple shell-\n  and beam-type oscillations of single-walled carbon nanotubes: We demonstrate the application of the efficient semi-inverse asymptotic\nmethod to resonant interaction of the nonlinear normal modes belonging to\ndifferent branches of the CNT vibration spectrum. Under condition of the 1:1\nresonance of the beam and circumferential flexure modes we obtain the dynamical\nequations, the solutions of which describe the coupled stationary states. The\nlatter are characterized by the non-uniform distribution of the energy along\nthe circumferential coordinate. The non-stationary solutions for obtained\nequations correspond to the slow change of the energy distribution. It is shown\nthat adequate description of considered resonance processes can be achieved in\nthe domain variables. They are the linear combinations of the shell- and\nbeam-type normal modes. Using such variables we have analyzed not only\nnonlinear normal modes but also the limiting phase trajectories describing the\nstrongly non-stationary dynamics. The evolution of the considered resonance\nprocesses with the oscillation amplitude growth is analyzed by the phase\nportrait method and verified by the numerical integration of the respective\ndynamical equations."
    },
    {
        "anchor": "Dipolar interactions enhanced by two-dimensional dielectric screening in\n  few-layer van der Waals structures: We theoretically examined how the dielectric screening of two-dimensional\nlayered materials affects the dipolar interaction between interlayer excitons\nin few-layer van der Waals structures. Our analysis indicates that the dipolar\ninteraction is largely enhanced by two-dimensional dielectric screening at an\ninter-exciton separation of several nanometers or larger. The underlying\nmechanism can be attributed to the induced-charge densities in layered\nmaterials, which give rise to induced-dipole densities at large distances with\ndirections parallel to that of the interlayer exciton. The interaction between\nquadrupolar excitons in trilayer structures are found to be enhanced even\nlarger, with a magnitude one to two orders stronger than that without 2D\ndielectric screening. The strengths of these dipolar and quadrupolar\ninteractions can be further tuned by engineering the dielectric environment.",
        "positive": "Characterization of the Energy Structure and Adiabatic Magnetization\n  Process of V15: The energy structure of the V$_{15}$ is studied using exact diagonalization\nmethods, and the adiabatic changes of the magnetization in the system with the\nsweeping field are investigated. We confirm that the Dzyaloshinskii-Moriya\ninteraction leads to an energy gap which allows the adiabatic change of the\nmagnetization which has been found experimentally by Chiorescu et al., and also\npredict novel dynamics of the magnetization due to this energy level structure."
    },
    {
        "anchor": "Multi-layered atomic relaxation in van der Waals heterostructures: When two-dimensional van der Waals materials are stacked to build\nheterostructures, moir\\'e patterns emerge from twisted interfaces or from\nmismatch in lattice constant of individual layers. Relaxation of the atomic\npositions is a direct, generic consequence of the moir\\'e pattern, with many\nimplications for the physical properties. Moir\\'e driven atomic relaxation may\nbe naively thought to be restricted to the interfacial layers and thus\nirrelevant for multi-layered heterostructures. However, we provide experimental\nevidence for the importance of the three dimensional nature of the relaxation\nin two types of van der Waals heterostructures: First, in multi-layer graphene\ntwisted on graphite at small twist angles ($\\theta\\approx0.14^\\circ$) we\nobserve propagation of relaxation domains even beyond 18 graphene layers.\nSecond, we show how for multi-layer PdTe$_2$ on Bi$_2$Se$_3$ the moir\\'e\nlattice constant depends on the number of PdTe$_2$ layers. Motivated by the\nexperimental findings, we developed a continuum approach to model multi-layered\nrelaxation processes based on the generalized stacking fault energy functional\ngiven by ab-initio simulations. Leveraging the continuum property of the\napproach enables us to access large scale regimes and achieve agreement with\nour experimental data for both systems. Furthermore it is well known that the\nelectronic structure of graphene sensitively depends on local lattice\ndeformations. Therefore we study the impact of multi-layered relaxation on the\nlocal density of states of the twisted graphitic system. We identify measurable\nimplications for the system, experimentally accessible by scanning tunneling\nmicroscopy. Our multi-layered relaxation approach is not restricted to the\ndiscussed systems, and can be used to uncover the impact of an interfacial\ndefect on various layered systems of interest.",
        "positive": "Bolometric detection of Josephson radiation: A Josephson junction (JJ) has been under intensive study ever since 1960's.\nYet even in the present era of building quantum information processing devices\nbased on many JJs, open questions regarding a single junction remain unsolved,\nsuch as quantum phase transitions, coupling of the JJ to an environment and\nimproving coherence of a superconducting qubit. Here we design and build an\nengineered on-chip reservoir that acts as an efficient bolometer for detecting\nthe Josephson radiation under non-equilibrium (biased) conditions. The\nbolometer converts ac Josephson current at microwave frequencies, up to about\n$100\\,$GHz, into a measurable dc temperature rise. The present experiment\ndemonstrates an efficient, wide-band, thermal detection scheme of microwave\nphotons and provides a sensitive detector of Josephson dynamics beyond the\nstandard conductance measurements. Using a circuit model, we capture both the\ncurrent-voltage characteristics and the measured power quantitatively."
    },
    {
        "anchor": "Validity of the Lowest Landau Level Approximation for Rotating Bose\n  Gases: The energy spectrum for an ultracold rotating Bose gas in a harmonic trap is\ncalculated exactly for small systems, allowing the atoms to occupy several\nLandau levels. Two vortex-like states and two strongly correlated states (the\nPfaffian and Laughlin) are considered in detail. In particular, their critical\nrotation frequencies and energy gaps are determined as a function of particle\nnumber, interaction strength, and the number of Landau levels occupied (up to\nthree). For the vortex-like states, the Lowest Landau level (LLL) approximation\nis justified only if the interaction strength decreases with the number of\nparticles; nevertheless, the constant of proportionality increases rapidly with\nthe angular momentum per particle. For the strongly correlated states, however,\nthe interaction strength can increase with particle number without violating\nthe LLL condition. The results suggest that in large systems, the Pfaffian and\nLaughlin states might be stabilized at rotation frequencies below the\ncentrifugal limit for sufficiently large interaction strengths, with energy\ngaps a significant fraction of the trap energy.",
        "positive": "Second Harmonic Generation in Graphene: We report on theoretical study of second harmonic generation in graphene.\nPhenomenological analysis based on symmetry arguments is carried out. It is\ndemontrated, that in ideal graphene samples second harmonic generation is\npossible only if the radiation wave vector or its magnetic field is taken into\naccount. Microscopic theory is developed for the classical regime of radiation\ninteraction with electrons, where photon energy is much smaller than the charge\ncarriers characteristic energy. It is demonstrated, that the emitted radiation\ncan be strongly circularly polarized for the linearly polarized incident wave."
    },
    {
        "anchor": "Stability, Tunneling Characteristics and Thermoelectric Properties of\n  TeSe2 allotropes: The waste heat management becomes very important with increasing energy\ndemand and limited fossil resources. Here, we demonstrate thermoelectric\nperformance of allotropic TeSe2. Based on the first-principle calculations, we\nconfirm the energetic and kinetic stability of five TeSe2 allotropes. We\npredict {\\delta}-TeSe2 as a new direct band gap semiconductor having 1.60 eV\ndirect band gap. All the TeSe2 allotropes exhibit band gap in UV-Vis region.\nThe structural phases are clearly distinguished using simulated scanning tunnel\nmicroscopy. The room temperature Seebeck coefficient is maximum of 4 V/K for\n{\\delta}-TeSe2. We show that room temperature thermoelectric figure of merit\n(ZT) can reach up to 3.1 with p-type doping in {\\delta}-TeSe2. Moreover,\ntemperature and chemical potential tuning extends the thermoelectric\nperformance of TeSe2 allotropes. We strongly believe that our study is\ncompelling from an experimental perspective and holds a key towards fabrication\nof thermoelectric devices based on TeSe2.",
        "positive": "Double quantum dot with integrated charge sensor based on Ge/Si\n  heterostructure nanowires: Coupled electron spins in semiconductor double quantum dots hold promise as\nthe basis for solid-state qubits. To date, most experiments have used III-V\nmaterials, in which coherence is limited by hyperfine interactions. Ge/Si\nheterostructure nanowires seem ideally suited to overcome this limitation: the\npredominance of spin-zero nuclei suppresses the hyperfine interaction and\nchemical synthesis creates a clean and defect-free system with highly\ncontrollable properties. Here we present a top gate-defined double quantum dot\nbased on Ge/Si heterostructure nanowires with fully tunable coupling between\nthe dots and to the leads. We also demonstrate a novel approach to charge\nsensing in a one-dimensional nanostructure by capacitively coupling the double\ndot to a single dot on an adjacent nanowire. The double quantum dot and\nintegrated charge sensor serve as an essential building block required to form\na solid-state spin qubit free of nuclear spin."
    },
    {
        "anchor": "Microwave spectroscopy of Andreev states in InAs nanowire-based hybrid\n  junctions using a flip-chip layout: Josephson junctions based on semiconductor nanowires are potential building\nblocks for electrically tunable qubit structures, e.g. the gatemon or the\nAndreev qubit. However, an actual realization requires the thorough\ninvestigation of the intrinsic excitation spectrum. Here, we demonstrate the\nfabrication of low-loss superconducting microwave circuits that combine high\nquality factors with a well-controlled gate architecture by utilizing a\nflip-chip approach. This platform is then used to perform single-tone and\ntwo-tone experiments on Andreev states in in-situ grown InAs/Al core/half-shell\nnanowires with shadow mask defined Josephson junctions. In gate-controlled and\nflux-biased spectroscopic measurements we find clear signatures of single\nquasiparticle as well as quasiparticle pair transitions between discrete\nAndreev bound states mediated by photon-absorption. Our experimental findings\nare supported by simulations that show that the junction resides in the\nintermediate channel length regime.",
        "positive": "Giant spin orbit interaction due to rotating magnetic fields in graphene\n  nanoribbons: We theoretically study graphene nanoribbons in the presence of spatially\nvarying magnetic fields produced e.g. by nanomagnets. We show both analytically\nand numerically that an exceptionally large Rashba spin orbit interaction (SOI)\nof the order of 10 meV can be produced by the non-uniform magnetic field. As a\nconsequence, helical modes exist in armchair nanoribbons that exhibit nearly\nperfect spin polarization and are robust against boundary defects. This paves\nthe way to realizing spin filter devices in graphene nanoribbons in the\ntemperature regime of a few Kelvins. If a nanoribbon in the helical regime is\nin proximity contact to an s-wave superconductor, the nanoribbon can be tuned\ninto a topological phase sustaining Majorana fermions."
    },
    {
        "anchor": "Second Harmonic Generation of MoSi2N4 Layer: The recently discovered two-dimensional (2D) layered semiconductor MoSi2N4\nhas aroused great interest due to its unique 2D material characteristics. In\nthis Letter, we found that differences in the structural details for MoSi2N4\nmay lead to differences in the intensity of second harmonic generation (SHG)\nand its response to strain. Accordingly, SHG can be used as a simple technique\nto identify the structural details of this system. We further calculated the\nSHG effects of MoSi2N4 derivatives and investigated their strain-regulation\nmechanism, especially including the anomalous SHG responses under strain for\nMoSi2P4 and MoGe2P4, differing from other known 2D materials. The studies may\nhave forward-looking significance for the research of nonlinear optics and\noptoelectronics in this novel 2D material system.",
        "positive": "Semiconductor membranes for electrostatic exciton trapping in optically\n  addressable quantum transport devices: Combining the capabilities of gate defined quantum transport devices in\nGaAs-based heterostructures and of optically addressed self-assembled quantum\ndots could open broad perspectives for new devices and functionalities. For\nexample, interfacing stationary solid-state qubits with photonic quantum states\nwould open a new pathway towards the realization of a quantum network with\nextended quantum processing capacity in each node. While gated devices allow\nvery flexible confinement of electrons or holes, the confinement of excitons\nwithout some element of self-assembly is much harder. To address this\nlimitation, we introduce a technique to realize exciton traps in quantum wells\nvia local electric fields by thinning a heterostructure down to a 220 nm thick\nmembrane. We show that mobilities over $1 \\times 10^{6}$\ncm$^{2}$V$^{-1}$s$^{-1}$ can be retained and that quantum point contacts and\nCoulomb oscillations can be observed on this structure, which implies that the\nthinning does not compromise the heterostructure quality. Furthermore, the\nlocal lowering of the exciton energy via the quantum-confined Stark effect is\nconfirmed, thus forming exciton traps. These results lay the technological\nfoundations for devices like single photon sources, spin photon interfaces and\neventually quantum network nodes in GaAs quantum wells, realized entirely with\na top-down fabrication process."
    },
    {
        "anchor": "Phonon-assisted transport through double-dot Aharonov-Bohm\n  interferometer in the Kondo regime: The effect of electron-phonon coupling on transport through a pair of\nstrongly correlated quantum dots embedded in the Aharonov-Bohm ring is\nconsidered in the mean field slave boson Kotliar-Ruckenstein approach. It is\nshown that coupling with phonons opens transport gap in the region of double\noccupancy. Low-bias conductance and thermopower provide information on\nelectron-phonon coupling strength.",
        "positive": "Strain-driven valley states and phase transitions in Janus VSiGeN4\n  monolayer: The interplay between topology and valley degree of freedom has attracted\nmuch interest because it can realize new phenomena and applications. Here,\nbased on first-principles calculations, we demonstrate intrinsically\nvalley-polarized quantum anomalous Hall effect in monolayer ferrovalley\nmaterial: Janus VSiGeN4, of which the edge states are chiral-spin-valley\nlocking. Besides, a small tensile or compressive strain can drive phase\ntransition in the material from valley-polarized quantum anomalous Hall state\nto half-valley-metal state. With the increase of the strain, the material turns\ninto ferrovalley semiconductor with valley anomalous Hall effect. The origin of\nphase transition is sequent band inversion of V d orbital at K valley.\nMoreover, we find that phase transition causes the sign reversal of Berry\ncurvature and induces different polarized light absorption in different valley\nstates. Our work provides an ideal material platform for practical applications\nand experimental exploration of the interplay between topology, spintronics,\nand valleytronics."
    },
    {
        "anchor": "Proposal for an all-electrical measurement of crossed Andreev reflection\n  in topological insulators: Using a generalized wave matching method we solve the full scattering problem\nfor quantum spin Hall insulator (QSHI) - superconductor (SC) - QSHI junctions.\nWe find that for systems narrow enough so that the bulk states in the SC part\ncouple both edges, the crossed Andreev reflection (CAR) is significant and the\nelectron cotunneling (T) and CAR become spatially separated. We study the\neffectiveness of this separation as a function of the system geometry and the\nlevel of doping in the SC. Moreover, we show that the spatial separation of\nboth effects allows for an all-electrical measurement of CAR and T separately\nin a 5-terminal setup or by using the spin selection of the quantum spin Hall\neffect in an H-bar structure.",
        "positive": "Tunable non-equilibrium Luttinger liquid based on counter-propagating\n  edge channels: We investigate energy transfer between counter-propagating quantum Hall edge\nchannels (ECs) in a two-dimensional electron system at filling factor \\nu=1.\nThe ECs are separated by a thin impenetrable potential barrier and Coulomb\ncoupled, thereby constituting a quasi one-dimensional analogue of a spinless\nLuttinger liquid (LL). We drive one, say hot, EC far from thermal equilibrium\nand measure the energy transfer rate P into the second, cold, EC using a\nquantum point contact as a bolometer. The dependence of P on the drive bias\nindicates breakdown of the momentum conservation, whereas P is almost\nindependent on the length of the region where the ECs interact. Interpreting\nour results in terms of plasmons (collective density excitations), we find that\nthe energy transfer between the ECs occurs via plasmon backscattering at the\nboundaries of the LL. The backscattering probability is determined by the LL\ninteraction parameter and can be tuned by changing the width of the\nelectrostatic potential barrier between the ECs."
    },
    {
        "anchor": "Resonant electronic states and I-V curves of Fe/MgO/Fe(100) tunnel\n  junctions: The bias dependence of the tunnel magnetoresistance (TMR) of Fe/MgO/Fe tunnel\njunctions is investigated theoretically with a fully self-consistent scheme\nthat combines the non-equilibrium Green's functions method with density\nfunctional theory. At voltages smaller than 20 mVolt the I-V characteristics\nand the TMR are dominated by resonant transport through narrow interface states\nin the minority spin-band. In the parallel configuration this contribution is\nquenched by a voltage comparable to the energy width of the interface state,\nwhereas it persists at all voltages in the anti-parallel configuration. At\nhigher bias the transport is mainly determined by the relative positions of the\n$\\Delta_1$ band-edges in the two Fe electrodes, which causes a decrease of the\nTMR.",
        "positive": "Surface plasmons at composite surfaces with diffusive charges: Metal surfaces with disorder or with nanostructure modifications are studied,\nallowing for a localized charge layer (CL) in addition to continuous charges\n(CC) in the bulk, both charges having a compressional or diffusive non-local\nresponse. The notorious problem of \"additional boundary conditions\" is resolved\nwith the help of a Boltzmann equation that involves the scattering between the\ntwo charge types. Depending on the strength of this scattering, the oscillating\ncharges can be dominantly CC or CL; the surface plasmon (SP) resonance acquires\nthen a relatively small linewidth, in agreement with a large set of data. With\na few parameters our model describes a large variety of SP dispersions\ncorresponding to observed data."
    },
    {
        "anchor": "Incommensurate quantum-size oscillations in acene-based molecular wires\n  - effects of quantum fluctuations: Molecular wires of the acene-family can be viewed as a physical realization\nof a two-rung ladder Hamiltonian. For acene-ladders, closed-shell ab-initio\ncalculations and elementary zone-folding arguments predict incommensurate gap\noscillations as a function of the number of repetitive ring units,\n$N_{\\text{R}}$, exhibiting a period of about ten rings. %% Results employing\nopen-shell calculations and a mean-field treatment of interactions suggest\nanti-ferromagnetic correlations that could potentially open a large gap and\nwash out the gap oscillations. % Within the framework of a Hubbard model with\nrepulsive on-site interaction, $U$, we employ a Hartree-Fock analysis and the\ndensity matrix renormalization group to investigate the interplay of gap\noscillations and interactions. % We confirm the persistence of incommensurate\noscillations in acene-type ladder systems for a significant fraction of\nparameter space spanned by $U$ and $N_{\\text{R}}$.",
        "positive": "Coulomb drag in anisotropic systems: a theoretical study on a\n  double-layer phosphorene: We theoretically study the Coulomb drag resistivity in a double-layer\nelectron system with highly anisotropic parabolic band structure using\nBoltzmann transport theory. As an example, we consider a double-layer\nphosphorene on which we apply our formalism. This approach, in principle, can\nbe tuned for other double-layered systems with paraboloidal band structures.\nOur calculations show the rotation of one layer with respect to another layer\ncan be considered a way of controlling the drag resistivity in such systems. As\na result of rotation, the off-diagonal elements of drag resistivity tensor have\nnon-zero values at any temperature. In addition, we show that the anisotropic\ndrag resistivity is very sensitive to the direction of momentum transfer\nbetween two layers due to highly anisotropic inter-layer electron-electron\ninteraction and also the plasmon modes. In particular, the drag anisotropy\nratio, \\r{ho}yy/\\r{ho}xx, can reach up to ~ 3 by changing the temperature.\nFurthermore,our calculations suggest that including the local field correction\nin dielectric function changes the results significantly. Finally, We examine\nthe dependence of drag resistivity and its anisotropy ratio on various\nparameters like inter-layer separation, electron density, short-range\ninteraction and insulating substrate/spacer."
    },
    {
        "anchor": "Green's function technique for a two-electrode mesoscopic system under\n  bias: We present a Green's function technique for studying the nonlinear\nconductance of a nanocontact system with two electrodes at different chemical\npotentials. The retarded Green's function for a single-impurity Anderson model\nwith two reservoirs is obtained in terms of a $5\\times 5$ matrix in which the\neffect of bias is contained. A complete set of basis vectors for the\nsingle-impurity Anderson model has been provided before formulating the Green's\nfunction. Finally, we present a self-consistent method to fix the undetermined\nquantities existing in the matrix elements for the retarded Green's function.",
        "positive": "Kinetic approach to the nuclear-spin polaron formation: Under optical cooling of nuclei, a strongly correlated nuclear-spin polaron\nstate can form in semiconductor nanostructures with localized charge carriers\ndue to the strong hyperfine interaction of the localized electron spin with the\nsurrounding nuclear spins. Here we develop a kinetic-equation formalism\ndescribing the nuclear-spin polaron formation. We present a derivation of the\nkinetic equations for an electron-nuclear spin system coupled to reservoirs of\ndifferent electron and nuclear spin temperatures which generate the exact\nthermodynamic steady state for equal temperatures independent of the system\nsize. We illustrate our approach using the analytical solution of the central\nspin model in the limit of an Ising form of the hyperfine coupling. For\nhomogeneous hyperfine coupling constants, i.e., the box model, the model is\nreduced to an analytically solvable form. Based on the analysis of the\nnuclear-spin distribution function and the electron-nuclear spin correlators,\nwe derive a relation between the electron and nuclear spin temperatures, where\nthe correlated nuclear-spin polaron state is formed. In the limit of large\nnuclear baths, this temperature line coincides with the critical temperature of\nthe mean-field theory for polaron formation. The criteria of the polaron\nformation in a finite-size system are discussed. We demonstrate that the\nsystem's behavior at the transition temperature does not depend on details of\nthe hyperfine-coupling distribution function but only on the effective number\nof coupled bath spins. In addition, the kinetic equations enable the analysis\nof the temporal formation of the nuclear-polaron state, where we find the\nbuild-up process predominated by the nuclear spin-flip dynamics."
    },
    {
        "anchor": "Hyperfine-mediated transitions between a Zeeman split doublet in GaAs\n  quantum dots: The role of the internal field: We consider the hyperfine-mediated transition rate between Zeeman split spin\nstates of the lowest orbital level in a GaAs quantum dot. We separate the\nhyperfine Hamiltonian into a part which is diagonal in the orbital states and\nanother one which mixes different orbitals. The diagonal part gives rise to an\neffective (internal) magnetic field which, in addition to an external magnetic\nfield, determines the Zeeman splitting. Spin-flip transitions in the dots are\ninduced by the orbital mixing part accompanied by an emission of a phonon. We\nevaluate the rate for different regimes of applied magnetic field and\ntemperature. The rates we find are bigger that the spin-orbit related rates\nprovided the external magnetic field is sufficiently low.",
        "positive": "Temperature Dependence of Electric Transport in Few-layer Graphene under\n  Large Charge Doping Induced by Electrochemical Gating: The temperature dependence of electric transport properties of single-layer\nand few-layer graphene at large charge doping is of great interest both for the\nstudy of the scattering processes dominating the conductivity at different\ntemperatures and in view of the theoretically predicted possibility to reach\nthe superconducting state in such extreme conditions. Here we present the\nresults obtained in 3-, 4- and 5-layer graphene devices down to 3.5 K, where a\nlarge surface charge density up to about 6.8x10^14 cm^(-2) has been reached by\nemploying a novel polymer electrolyte solution for the electrochemical gating.\nIn contrast with recent results obtained in single-layer graphene, the\ntemperature dependence of the sheet resistance between 20 K and 280 K shows a\nlow-temperature dominance of a T^2 component - that can be associated with\nelectron-electron scattering - and, at about 100 K, a crossover to the classic\nelectron-phonon regime. Unexpectedly this crossover does not show any\ndependence on the induced charge density, i.e. on the large tuning of the Fermi\nenergy."
    },
    {
        "anchor": "Anisotropic nuclear-spin diffusion in double quantum wells: Nuclear-spin diffusion in double quantum wells (QWs) is examined by using\ndynamic nuclear polarization (DNP) at a Landau level filling factor $\\nu=2/3$\nspin phase transition (SPT). The longitudinal resistance increases during the\nDNP of one of the two QW (the polarization QW) by means of a large applied\ncurrent and starts to decrease just after the termination of the DNP. On the\nother hand, the longitudinal resistance of the other QW (the detection QW)\ncontinuously increases for approximately 2h after the termination of the DNP of\nthe polarization QW. It is therefore concluded that the nuclear spins diffuse\nfrom the polarization QW to the detection QW. The time evolution of the\nlongitudinal resistance of the polarization QW is explained mainly by the\nnuclear-spin diffusion in the in-plane direction. In contrast, that of the\ndetection QW manifests much slower nuclear diffusion in the perpendicular\ndirection through the AlGaAs barrier.",
        "positive": "Angular momentum and topology in semiconducting single-wall carbon\n  nanotubes: Semiconducting single-wall carbon nanotubes are classified into two types by\nmeans of orbital angular momentum of valley state, which is useful to study\ntheir low energy electronic properties in finite-length. The classification is\ngiven by an integer $d$, which is the greatest common divisor of two integers\n$n$ and $m$ specifying the chirality of nanotubes, by analyzing cutting lines.\nFor the case that $d$ is equal to or greater than four, two lowest subbands\nfrom two valleys have different angular momenta with respect to the nanotube\naxis. Reflecting the decoupling of two valleys, discrete energy levels in\nfinite-length nanotubes exhibit nearly fourfold degeneracy and its small lift\nby the spin-orbit interaction. For the case that $d$ is less than or equal to\ntwo, in which two lowest subbands from two valleys have the same angular\nmomentum, discrete levels exhibit lift of fourfold degeneracy reflecting the\ncoupling of two valleys. Especially, two valleys are strongly coupled when the\nchirality is close to the armchair chirality. An effective one-dimensional\nlattice model is derived by extracting states with relevant angular momentum,\nwhich reveals the valley coupling in the eigenstates. A bulk-edge\ncorrespondence, relationship between number of edge states and the winding\nnumber calculated in the corresponding bulk system, is analytically shown by\nusing the argument principle, which enables us to estimate the number of edge\nstates from the bulk property. The number of edge states depends not only on\nthe chirality but also on the shape of boundary."
    },
    {
        "anchor": "Probing Landau levels of strongly interacting massive Dirac electrons in\n  layer-polarized MoS$_2$: Monolayer transition metal dichalcogenides are recently emerged 2D electronic\nsystems with various novel properties, such as spin-valley locking, circular\ndichroism, valley Hall effects, Ising superconductivity. The reduced\ndimensionality and large effective masses further produce unconventional\nmany-body interaction effects. Although recent hole transport measurements in\nWSe$_2$ indicate strong interactions in the valence bands, many-body\ninteraction effects, particularly in the conduction bands, remain elusive to\ndate. Here, for the first time, we perform transport measurements up to a\nmagnetic field of $29$T to study the massive Dirac electron Landau levels (LL)\nin layer-polarized MoS$_2$ samples with mobilities of $22000$cm$^2$/(V$\\cdot$s)\nat $1.5$K and densities of $\\sim10^{12}$cm$^{-2}$. With decreasing the density,\nwe observe LL crossing induced valley ferrimagnet-to-ferromagnet transitions,\nas a result of the interaction enhancement of the g-factor from $5.64$ to\n$21.82$. Near integer ratios of Zeeman-to-cyclotron energies, we discover LL\nanticrossings due to the formation of quantum Hall Ising ferromagnets, the\nvalley polarizations of which appear to be reversible by tuning the density or\nan in-plane magnetic field. Our results provide compelling evidence for\nmany-body interaction effects in the conduction bands of monolayer MoS$_2$ and\nestablish a fertile ground for exploring strongly correlated phenomena of\nmassive Dirac electrons.",
        "positive": "Topological characterization of Landau levels for $2$D massless Dirac\n  fermions in $3$D layered systems: A topological concern is addressed in view of the extensively and intensively\nstudied topological phases of condensed matter. In this realm, the phases with\ntopological order cannot be characterized by symmetry alone. Moreover, the\nrelevant phase transitions do occur without spontaneous symmetry breaking,\nbeyond the scope of Landau's theory. The first realization of such phases is\nthe discovery of the integer quantum Hall effect (QHE), which was followed soon\nby a topological interpretation. Later on, a distinct, half-integer QHE was\nalso found from graphene, which has almost spin degeneracy described by $SU(2)$\nsymmetry. The previous theoretical predictions were realized in this finding.\nIt has been well understood that the anomaly of this half-integer QHE\noriginates from the presence of $2$D massless Dirac fermions around the zero\nenergy with respect to the original Dirac points (DPs). The very characteristic\nlies in that there exists a topologically robust zero-mode LL that is a\nconstant function of the perpendicular magnetic field. More deeply, this\nzero-mode LL is protected by the local chiral symmetry (CS), against CS\npreserving perturbations provided that intervalley scattering between the\ndouble DPs is inhibited, where the CS arises from the global sublattice\nsymmetry in spinless graphene. Since massless Dirac particles are broadly\npresent in condensed matter with various symmetries, not to mention Dirac\nbosonic systems, it is of interest to see how about the situations in other\nsystems with $2$D massless Dirac fermions. We address several notes in a\ntopological viewpoint on the presence of $2$D massless Dirac fermions in $3$D\nlayered systems.In particular, we focus on the zero-mode LL since this LL\nsignifies $2$D massless Dirac fermions."
    },
    {
        "anchor": "Coulomb Blockade from the Shell of an InP-InAs Core-Shell Nanowire with\n  a Triangular Cross Section: We report on growth of InP-InAs core-shell nanowires and demonstration of the\nformation of single quantum structures, which show Coulomb blockade effect,\nover entire lengths of the nanowires. The core-shell nanowires are grown by a\nselective area growth technique via metal-organic vapor phase epitaxy. The\nas-grown core-shell nanowires are found to be of wurtzite crystals. The InP\ncores have a hexagonal cross section, while the InAs shell are grown\npreferentially on specific {1$\\bar{1}$00} facets, leading to the formation of\nthe core-shell nanowires with an overall triangular cross section. The grown\ncore-shell nanowires are transferred on to a Si/SiO$_2$ substrate and then\ncontacted with several narrow metal electrodes. Low-temperature transport\nmeasurements show the Coulomb-blockade effect. We analyze the measured gate\ncapacitance and single electron charging energy of the devices and demonstrate\nthat a quantum structure which shows the Coulomb blockade effect of a\nmany-electron quantum dot is formed over the full length of a single core-shell\nnanowire and consists of the entire InAs shell in the nanowire.",
        "positive": "Universal description of potential energy surface of interlayer\n  interaction in two-dimensional materials by first spatial Fourier harmonics: We propose a hypothesis that the potential energy surface (PES) of interlayer\ninteraction in diverse 2D materials can be universally described by the first\nspatial Fourier harmonics. This statement (checked previously for the\ninteractions between graphene and hexagonal boron nitride layers in different\ncombinations) is verified in the present paper for the case of hydrofluorinated\ngraphene (HFG) bilayer with hydrogen bonding between fluorine and hydrogen at\nthe interlayer interface. The PES for HFG bilayer is obtained through density\nfunctional theory calculations with van der Waals corrections. An analytical\nexpression based on the first Fourier harmonics describing the PES which\ncorresponds to the symmetry of HFG layers is derived. It is found that the\ncalculated PES can be described by the first Fourier harmonics with the\naccuracy of 3\\% relative to the PES corrugation. The shear mode frequency,\nshear modulus and barrier for relative rotation of the layers to incommensurate\nstates of HFG bilayer are estimated. Additionally it is shown that HFG bilayer\nis stable relative to the formation of HF molecules as a result of chemical\nreactions between the layers."
    },
    {
        "anchor": "Eigenvalues and Eigenfunctions of Two Coupled Normal Metal Nano-rings: A general scheme is developed to deal with 1D lattice systems that could be\ntopologically complicated. It is aimed to give a complete study of two coupled\nnormal metal rings. Our method starts with an investigation of the local\nexpressions of the eigenfunctions. By connecting different parts of the system,\nall the eigenvalues and eigenfunctions can be obtained. It is found that there\nis a possibility for the existence of localized states, which is beyond\nprevious expectations.",
        "positive": "Spin Hall Effect in Doped Semiconductor Structures: In this Letter we present a microscopic theory of the extrinsic spin Hall\neffect based on the diagrammatic perturbation theory. Side-jump (SJ) and\nskew-scattering (SS) contributions are explicitly taken into account to\ncalculate the spin Hall conductivity, and we show their effects scale as\n$\\sigma_{xy}^{SJ}/\\sigma_{xy}^{SS} \\sim (\\hbar/\\tau)/\\epsilon_F$, with $\\tau$\nbeing the transport relaxation time. Motivated by recent experimental work we\napply our theory to n- and p-doped 3D and 2D GaAs structures, obtaining\n$\\sigma_s/\\sigma_c \\sim 10^{-3}-10^{-4}$ where $\\sigma_{s(c)}$ is the spin Hall\n(charge) conductivity, which is in reasonable agreement with the recent\nexperimental results of Kato \\textit{et al}. [Science \\textbf{306}, 1910\n(2004)] in n-doped 3D GaAs system."
    },
    {
        "anchor": "Composite fermions in the half-filled lowest Landau level: a macroscopic\n  justification: An effective Hamiltonian for spinless electrons in the lowest Landau level\n(LLL) close to half filling is derived. As opposed to the treatment in standard\nChern-Simons theories (CS) we first project to the LLL and only then apply a\nCS-transformation on the Hamiltonian. The transformed field operators act in\nthe lowest Landau level only {\\it and} have fermionic commutation relations for\nsmall wavenumbers ignoring gauge field fluctuations. When acting on the\nHamiltonian at half filling the {\\it gauge transformation removes the monopole\nterm in the interaction and does not eliminate the magnetic field.",
        "positive": "Collective excitations in Quantum Dot: We investigate different types of collective excitations in a quantum dot\ncontaining finite number of electrons at zero magnetic field. To estimate the\nexcitation energies analytically we follow the energy weighted sum-rule\napproach. We consider the most general multipole excitation with angular\nmomentum l, and the breathing mode excitation (monopole excitation) of a large\nquantum dot, for three different types of effective electron-electron\ninteraction. These are the logarithmic interaction, the short range\npseudopotential and the coulomb interaction. The ground state density of the\nmany-body system is calculated within Thomas-Fermi approximation. The\nanalytical results for the collective excitation energies and their dependence\non the system size and other external parameters are discussed in detail."
    },
    {
        "anchor": "Dipoles and fractional quantum Hall masses: We develop a microscopic formalism to study the fractional quantum Hall\nplateaus at filling factors $\\nu $ away from $1/2\\beta$ $\\beta$ an integer. The\ntheory is in terms of quasiparticles which carry a charge $e^{\\ast}$ equal to\n$1-2\\beta\\nu $ times the charge of the electron. The wave functions obtained\nfollowing our approach are shown to coincide precisely with the form predicted\nby Jain and this holds independently of the interaction potential.\\\nMicroscopically this rigidity originates from the fact that two different\ncharges interacting attractively in their lowest Landau levels form a bound\nstate with a universal wave function. From the expressions of the gaps we\ncompute an effective mass which agrees well with the experiments carried at\n$\\nu=1/2$ and 1/4.",
        "positive": "Quantum transport through a \"charge\" Kondo circuit: effects of weak\n  repulsive interaction in Luttinger Liquid: We investigate theoretically quantum transport through the \"charge\" Kondo\ncircuit consisting of the quantum dot (QD) coupled weakly to an electrode at\ntemperature $T+\\Delta T$ and connected strongly to another electrode at the\nreference temperature $T$ by a single-mode quantum point contact (QPC). To\naccount for the effects of Coulomb interaction in the QD-QPC setup operating in\nthe integer quantum Hall regime we describe the edge current in the quantum\ncircuit by Luttinger model characterized by the Luttinger parameter $g$. It is\nshown that the temperature dependence of both electric conductance $G\\propto\nT^{2/g}$ and thermoelectric coefficient $G_T\\propto T^{1+2/g}$ detours from the\nFermi-liquid (FL) theory predictions. The behaviour of the thermoelectric power\n$S=G_T/G\\propto T$ in a regime of a single-channel Kondo effect is, by\ncontrast, consistent with the FL paradigm. We demonstrate that the interplay\nbetween the mesoscopic Coulomb blockade in QD and weak repulsive interaction in\nthe Luttinger Liquid $g=1-\\alpha$ $(\\alpha \\ll 1)$ results in the enhancement\nof the thermopower. This enhancement is attributed to suppression of the Kondo\ncorrelations in the \"charge\" circuit by the destructive quantum interference\neffects."
    },
    {
        "anchor": "Propagation and attenuation of sound in one-dimensional quantum liquids: At low temperatures, elementary excitations of a one-dimensional quantum\nliquid form a gas that can move as a whole with respect to the center of mass\nof the system. This internal motion attenuates at exponentially long time\nscales. As a result, in a broad range of frequencies the liquid is described by\ntwo-fluid hydrodynamics, and the system supports two sound modes. The physical\nnature of the two sounds depends on whether the particles forming the quantum\nliquid have a spin degree of freedom. For particles with spin, the modes are\nanalogous to the first and second sound modes in superfluid $^4$He, which are\nthe waves of density and entropy, respectively. When dissipative processes are\ntaken into account, we find that at low frequencies the second sound is\ntransformed into heat diffusion, while the first sound mode remains weakly\ndamped and becomes the ordinary sound. In a spinless liquid the entropy and\ndensity oscillations are strongly coupled, and the resulting sound modes are\nhybrids of the first and second sound. As the frequency is lowered and\ndissipation processes become important, the crossover to single-fluid regime\noccurs in two steps. First the hybrid modes transform into predominantly\ndensity and entropy waves, similar to the first and second sound, and then the\ndensity wave transforms to the ordinary sound and the entropy wave becomes a\nheat diffusion mode. Finally, we account for the dissipation due to viscosity\nand intrinsic thermal conductivity of the gas of excitations, which controls\nattenuation of the sound modes at high frequencies.",
        "positive": "Bilayer Graphene Interferometry : Phase Jump and Wave Collimation: We theoretically study the phase of the reflection amplitude of an electron\n(massive Dirac fermion) at a lateral potential step in Bernal-stacked bilayer\ngraphene. The phase shows anomalous jump of $\\pi$, as the electron incidence\nangle (relative to the normal direction to the step) varies to pass $\\pm\n\\pi/4$. The jump is attributed to the Berry phase associated with the\npseudospin-1/2 of the electron. This Berry-phase effect is robust against the\nband gap opening due to the external electric gates generating the step. We\npropose an interferometry setup in which collimated waves can be generated and\ntuned. By using the setup, one can identify both the $\\pi$ jump and the\ncollimation angle."
    },
    {
        "anchor": "Closed and open superconducting microwave waveguide networks as a model\n  for quantum graphs: We report on high-precision measurements that were performed with\nsuperconducting waveguide networks with the geometry of a tetrahedral and a\nhoneycomb graph. They consist of junctions of valency three that connect\nstraight rectangular waveguides of incommensurable lengths. The experiments\nwere performed in the frequency range of a single transversal mode, where the\nassociated Helmholtz equation is effectively one dimensional and waveguide\nnetworks may serve as models of quantum graphs with the joints and waveguides\ncorresponding to the vertices and bonds. The tetrahedral network comprises T\njunctions, while the honeycomb network exclusively consists of Y junctions,\nthat join waveguides with relative angles 90 degree and 120 degree,\nrespectively. We demonstrate that the vertex scattering matrix, which describes\nthe propagation of the modes through the junctions strongly depends on\nfrequency and is non-symmetric at a T junction and thus differs from that of a\nquantum graph with Neumann boundary conditions at the vertices. On the\ncontrary, at a Y junction, similarity can be achieved in a certain frequeny\nrange. We investigate the spectral properties of closed waveguide networks and\nfluctuation properties of the scattering matrix of open ones and find good\nagreement with random matrix theory predictions for the honeycomb waveguide\ngraph.",
        "positive": "Extending the Electron Spin Coherence Time of Atomic Hydrogen by\n  Dynamical Decoupling: We study the electron spin decoherence of encapsulated atomic hydrogen in\noctasilsesquioxane cages induced by the 1H and 29Si nuclear spin bath. By\napplying the Carr-Purcell-Meiboom-Gill (CPMG) pulse sequence we significantly\nsuppress the low-frequency noise due to nuclear spin flip-flops up to the point\nwhere a maximum T2 = 56 us is observed. Moreover, dynamical decoupling with the\nCPMG sequence reveals the existence of two sources of high-frequency noise:\nfirst, a fluctuating magnetic field with the proton Larmor frequency,\nequivalent to classical magnetic field noise imposed by the 1H nuclear spins of\nthe cage organic substituents, and second, decoherence due to entanglement\nbetween the electron and the inner 29Si nuclear spin of the cage."
    },
    {
        "anchor": "Reset and switch protocols at Landauer limit in a graphene buckled\n  ribbon: Heat produced during a reset operation is meant to show a fundamental bound\nknown as Landauer limit, while simple switch operations have an expected\nminimum amount of produced heat equal to zero. However, in both cases,\npresent-day technology realizations dissipate far beyond these theoretical\nlimits. In this paper we present a study based on molecular dynamics\nsimulations, where reset and switch protocols are applied on a graphene buckled\nribbon, employed here as a nano electromechanical switch working at the\nthermodynamic limit.",
        "positive": "Spin Hall Conductance in Disordered Two-Dimensional Electron Systems: We withdraw the paper because the results are wrong."
    },
    {
        "anchor": "Mean-field magnetization relaxation in conducting ferromagnets: Collective ferromagnetic motion in a conducting medium is damped by the\ntransfer of the magnetic moment and energy to the itinerant carriers. We\npresent a calculation of the corresponding magnetization relaxation as a\nlinear-response problem for the carrier dynamics in the effective exchange\nfield of the ferromagnet. In electron systems with little intrinsic spin-orbit\ninteraction, a uniform magnetization motion can be formally eliminated by going\ninto the rotating frame of reference for the spin dynamics. The ferromagnetic\ndamping in this case grows linearly with the spin-flip rate when the latter is\nsmaller than the exchange field and is inversely proportional to the spin-flip\nrate in the opposite limit. These two regimes are analogous to the\n\"spin-pumping\" and the \"breathing Fermi-surface\" damping mechanisms,\nrespectively. In diluted ferromagnetic semiconductors, the hole-mediated\nmagnetization can be efficiently relaxed to the itinerant-carrier degrees of\nfreedom due to the strong spin-orbit interaction in the valence bands.",
        "positive": "Higher-order non-Hermitian skin effect: The non-Hermitian skin effect is a unique feature of non-Hermitian systems,\nin which an extensive number of boundary modes appear under the open boundary\nconditions. Here, we discover higher-order counterparts of the non-Hermitian\nskin effect that exhibit new boundary physics. In two-dimensional systems with\nthe system size $L \\times L$, while the conventional (first-order) skin effect\naccompanies $O\\,( L^{2} )$ skin modes, the second-order skin effect accompanies\n$O\\,( L )$ corner skin modes. This also contrasts with Hermitian second-order\ntopological insulators, in which only $O\\,( 1 )$ corner zero modes appear.\nMoreover, for the third-order skin effect in three dimensions, $O\\,( L )$\ncorner skin modes appear from all $O\\,( L^{3} )$ modes. We demonstrate that the\nhigher-order skin effect originates from intrinsic non-Hermitian topology\nprotected by spatial symmetry. We also show that it accompanies the\nmodification of the non-Bloch band theory in higher dimensions."
    },
    {
        "anchor": "Nanostructure phase and interface engineering via controlled Au\n  self-assembly on GaAs(001) surface: We have investigated the temperature-dependent morphology and composition\nchanges occurring during a controlled self-assembling of thin Au film on the\nGallium arsenide (001) surface utilizing electron microscopy at nano and atomic\nlevels. It has been found that the deposition of 2 ML of Au at a substrate\ntemperature lower than 798 K leads to the formation of pure Au nanoislands. For\nthe deposition at a substrate temperature of about 798 K the nanostructures of\nthe stoichiometric AuGa phase were/had been grown. Gold deposition at higher\nsubstrate temperatures results in the formation of octagonal nanostructures\ncomposed of an AuGa2 alloy. We have proved that the temperature-controlled\nefficiency of Au-induced etching-like of the GaAs substrate follows in a\nlayer-by-layer manner leading to the enrichment of the substrate surface in\ngallium. The excess Ga together with Au forms liquid droplets which, while\ncooling the sample to room temperature, crystallize therein developing\ncrystalline nanostructures of atomically-sharp interfaces with the substrate.\nThe minimal stable cluster of 3 atoms and the activation energy for the surface\ndiffusion Ed=0.816+-0.038eV was determined. We show that by changing the\ntemperature of the self-assembling process one can control the phase, interface\nand the size of the nanostructures formed.",
        "positive": "Simulation of energy barrier distributions using real particle\n  parameters and comparison with experimental obtained results: In this work we compare previously measured energy barriers over the course\nof temperature with the results of simulations of the behaviour of the energy\nbarriers. For the measurements the temperature dependent magnetorelaxation\nmethod (TMRX) was used. For the simulations of the energy barrier distribution\nwe have used the real particles properties such as anisotropy and core size\nvolume of the fractions of two magnetically fractionated ferrofluids. There is\na good agreement between the simulated behaviour and the experimental obtained\nresults. The influence of the particle volume concentration and agglomeration\non the energy barrier distribution has been investigated. Finally the\nsimulations confirm a previously published explanation for an experimentally\nobtained relaxation effect."
    },
    {
        "anchor": "Long tunneling contact as a probe of fractional quantum Hall neutral\n  edge modes: We study the tunneling current between edge states of quantum Hall liquids\nacross a single long contact region, and predict a resonance at a bias voltage\nset by the scale of the edge velocity. For typical devices and edge velocities\nassociated with charged modes, this resonance occurs outside the physically\naccessible bias domain. However, for edge states that are expected to support\nneutral modes, such as the $\\nu={2/3}$, and $\\nu={5/2}$ Pfaffian and\nanti-Pfaffian states, the neutral velocity can be orders of magnitude smaller\nthan the charged mode and if so the resonance would be accessible. Therefore,\nsuch long tunneling contacts can resolve the presence of neutral edge modes in\ncertain quantum Hall liquids.",
        "positive": "Universality of Non-equilibrium Fluctuations in Strongly Correlated\n  Quantum Liquids: Interacting quantum many-body systems constitute a fascinating playground for\nresearchers since they form quantum liquids with correlated ground states and\nlow-lying excitations, which exhibit universal behaviour. In fermionic systems,\nsuch quantum liquids are realized in helium-3 liquid, heavy fermion systems,\nneutron stars and cold gases. Their properties in the linear-response regime\nhave been successfully described by the theory of Fermi liquids. However,\nnon-equilibrium properties beyond this regime have still to be established and\nremain a key issue of many-body physics. Here, we show a precise experimental\ndemonstration of Landau Fermi-liquid theory extended to the non-equilibrium\nregime in a 0-D system. Combining transport and ultra-sensitive current noise\nmeasurements, we have unambiguously identified the SU(2) and SU(4) symmetries\nof quantum liquid in a carbon nanotube tuned in the universal Kondo regime. We\nfind that, while the electronic transport is well described by the free\nquasi-particle picture around equilibrium, a two-particle scattering process\ndue to residual interaction shows up in the non-equilibrium regime. By using\nthe extended Fermi-liquid theory, we obtain the interaction parameter \"Wilson\nratio\" $R=1.9 \\pm 0.1$ for SU(2) and $R=1.35 \\pm 0.1$ for SU(4) as well as the\ncorresponding effective charges, characterizing the quantum liquid behaviour.\nThis result, in perfect agreement with theory, provides a strong quantitative\nexperimental background for further developments of the many-body physics.\nMoreover, we discovered a new scaling law for the effective charge, signalling\nas-yet-unknown universality in the non-equilibrium regime. Our method to\naddress quantum liquids through their non-equilibrium noise paves a new road to\ntackle the exotic nature of quantum liquids out-of-equilibrium in various\nphysical systems."
    },
    {
        "anchor": "Two-dimensional Asymptotic Generalized Brillouin Zone Theory: In this work, we propose a theory on the two-dimensional non-Hermitian skin\neffect by resolving two representative minimal models. Specifically, we show\nthat for any given non-Hermitian Hamiltonian, (i) the corresponding region\ncovered by its open boundary spectrum on the complex energy plane should be\nindependent of the open boundary geometry; and (ii) for any given open boundary\neigenvalue $E_0$ , its corresponding two-dimensional asymptotic generalized\nBrillouin zone is determined by a series of geometry-independent\nBloch/non-Bloch Fermi points and geometry-dependent non-Bloch equal frequency\ncontours that connect them. A corollary of our theory is that most\nsymmetry-protected exceptional semimetals should be robust to variations in OBC\ngeometry. Our theory paves the way to the discussion on the higher dimensional\nnon-Bloch band theory and the corresponding non-Hermitian bulk-boundary\ncorrespondence.",
        "positive": "Quantum Transport in Weyl Semimetal Thin Films in the Presence of\n  Spin-Orbit Coupled Impurities: Topological semimetals have been at the forefront of experimental and\ntheoretical attention in condensed matter physics. Among these, recently\ndiscovered Weyl semimetals have a dispersion described by a three-dimensional\nDirac cone, which is at the root of exotic physics such as the chiral anomaly\nin magnetotransport. In a time reversal symmetric (TRS) Weyl semimetal film,\nthe confinement gap gives the quasiparticles a mass, while TRS is preserved by\nhaving an even number of valleys with opposite masses. The film can be tuned\nthrough a topological phase transition by a gate electric field. In this work,\nwe present a theoretical study of the quantum corrections to the conductivity\nof a topological semimetal thin film, which is governed by the complex\ninterplay of the chiral band structure, mass term, and scalar and spin-orbit\nscattering. We study scalar and spin-orbit scattering mechanisms on the same\nfooting, demonstrating that they have a strong qualitative and quantitative\nimpact on the conductivity correction. We show that, due to the spin structure\nof the matrix Green's functions, terms linear in the extrinsic spin-orbit\nscattering are present in the Bloch and momentum relaxation times, whereas\nprevious works had identified corrections starting from the second order. In\nthe limit of small quasiparticle mass, the terms linear in the impurity\nspin-orbit coupling lead to a potentially observable density dependence in the\nweak antilocalization correction. Moreover, when the mass term is around 30\npercent of the linear Dirac terms, the system is in the unitary symmetry class\nwith zero quantum correction and switching the extrinsic spin-orbit scattering\ndrives the system to the weak antilocalization. We discuss the crossover\nbetween the weak localization and weak antilocalization regimes in terms of the\nsinglet and triplet Cooperon channels, tuning the spin-orbit scattering\nstrength."
    },
    {
        "anchor": "Observation of finite excess noise in the voltage-biased quantum Hall\n  regime as a precursor for breakdown: We performed noise measurements in a two-dimensional electron gas to\ninvestigate the nonequilibrium quantum Hall effect (QHE) state. While excess\nnoise is perfectly suppressed around the zero-biased QHE state reflecting the\ndissipationless electron transport of the QHE state, considerable finite excess\nnoise is observed in the breakdown regime of the QHE. The noise temperature\ndeduced from the excess noise is found to be of the same order as the energy\ngap between the highest occupied Landau level and the lowest empty one.\nMoreover, unexpected finite excess noise is observed at a finite source-drain\nbias voltagesmaller than the onset voltage of the QHE breakdown, which\nindicates finite dissipation in the QHE state and may be related to the\nprebreakdown of the QHE.",
        "positive": "Non-stationary transport properties of boundary states in Kitaev chain: We investigate the role of gap states in processes of perturbation\ntransmission along finite superconducting Kitaev chain. We look at this problem\non the general ground and use the formalism of non-stationary Greens functions,\nwhich contain full information about the non-equilibrium and non stationary\nproperties of the system. We discuss tunneling current and non-stationary\ntransport properties of a finite Kitaev chain with each edge connected to its\nown external lead. It is shown that the tunneling current is always\nexponentially small for long chains. The time dependent behavior of the\ntunneling current after the sudden change of bias voltage in one of the leads\nis also obtained. We investigate the characteristic time of charge transfer\nfrom the state at one end of the chain to the opposite edge state. We obtain\nthat this time always exponentially increases with the growth of the chain\nlength, and the relaxation time to the new equilibrium occupation number for\nthe localized state is very large. Our calculations are completely analytical\nand straightforward, in contrast with many other methods. Obtained results show\nhow quickly the \"second half\" of Majorana state responds after external\nperturbation acts on the \"first half\" and why \"Majorana\" states can hardly be\nused for any practical devices that require signal transmission from one end of\nthe system to the other."
    },
    {
        "anchor": "A Quantum Singlet Pump: We provide provide a detailed study of biasless coherent transport of singlet\nelectron pairs in one-dimensional (1D) channels induced by electron-electron\ninteractions that are time-varying in certain spatially localized regions of\nthe channel. When the time variation is cyclic, the mechanism is analogous to\nthe adiabatic quantum pumping of charge and spin previously studied. However,\nthe presence of interactions that vary only in localized regions of space\nrequires an intrinsically two-body description which is irreducible to the 1D\nsingle particle scattering matrix elements that are sufficient to describe\nquantum pumping of charge and spin. Here we derive a generalized theory for the\npumping of such interacting pairs starting from first principles. We show that\nthe standard description of charge pumping is contained within our more broadly\napplicable expressions. We then apply our general results to a concrete lattice\nmodel and obtain an exact analytical expression for the pumped singlet current.\nWe further demonstrate that such a model can be implemented with a chain of\ncurrently available quantum dots with certain minor modifications that we\nsuggest; we present a detailed numerical feasibility analysis of the\ncharacteristics of such experimentally realizable quantum dots, showing that\nthe requirements for a measurable pumped singlet current are within\nexperimental range.",
        "positive": "Effective capacitance in a single-electron transistor: Starting from the Kubo formula for conductance, we calculate the\nfrequency-dependent response of a single-electron transistor (SET) driven by an\nac signal. Treating tunneling processes within the lowest order approximation,\nvalid for a wide range of parameters, we discover a finite reactive part even\nunder Coulomb blockade due to virtual processes. At low frequencies this can be\ndescribed by an effective capacitance. This effect can be probed with microwave\nreflection measurements in radio-frequency (rf) SET provided that the\ncapacitance of the surroundings does not completely mask that of the SET."
    },
    {
        "anchor": "Signature of resonant modes in radiative heat current noise spectrum: Radiative heat transfer between bodies is often dominated by a narrow\nresonance in the transmission, e.~g. due to a cavity mode or a surface\nexcitation. However, this resonant character is not visible in the average heat\ncurrent. Here, we show that the noise spectrum of heat current can serve as a\ndirect probe of the heat-carrying excitations. Namely, the resonant mode\nproduces a sharp peak in the noise spectrum with a width related to the mode\nlifetime. We demonstrate that heat transfer in realistic superconducting\ncircuits or between two-dimensional metals can realize our predictions.",
        "positive": "Magnetic-field dependence of transport in normal and Andreev billiards:\n  a classical interpretation to the averaged quantum behavior: We perform a comparative study of the quantum and classical transport\nprobabilities of low-energy quasiparticles ballistically traversing normal and\nAndreev two-dimensional open cavities with a Sinai-billiard shape. We focus on\nthe dependence of the transport on the strength of an applied magnetic field\n$B$. With increasing field strength the classical dynamics changes from mixed\nto regular phase space. Averaging out the quantum fluctuations, we find an\nexcellent agreement between the quantum and classical transport coefficients in\nthe complete range of field strengths. This allows an overall description of\nthe non-monotonic behavior of the average magnetoconductance in terms of the\ncorresponding classical trajectories, thus, establishing a basic tool useful in\nthe design and analysis of experiments."
    },
    {
        "anchor": "Magnetic field induced confinement-deconfinement transition in graphene\n  quantum dots: Massless Dirac particles cannot be confined by an electrostatic potential.\nThis is a problem for making graphene quantum dots but confinement can be\nachieved with a magnetic field and here, general conditions for confined and\ndeconfined states are derived. There is a class of potentials for which the\ncharacter of the state can be controlled at will. Then a\nconfinement-deconfinement transition occurs which allows the Klein paradox to\nbe probed experimentally in graphene dots.",
        "positive": "Electric g Tensor Control and Spin Echo of a Hole-Spin Qubit in a\n  Quantum Dot Molecule: The feasibility of high-fidelity single-qubit operations of a hole spin in a\nquantum dot molecule by electric g tensor control is demonstrated. Apart from a\nconstant external magnetic field the proposed scheme allows for an exclusively\nelectric control of the hole spin. Realistic electric gate bias profiles are\nidentified for various qubit operations using process-tomography-based optimal\ncontrol. They are shown to be remarkably robust against decoherence and\ndissipation arising from the interaction of the hole with host-lattice nuclear\nspins and phonons, with a fidelity loss of $\\approx$ 1 percent for gate\noperation times of $\\approx 10$ ns. Spin-echo experiments for the hole spin are\nmodeled to explore dephasing mechanisms and the role of pulse-timing\nimperfections on the gate fidelity loss is discussed."
    },
    {
        "anchor": "Solitons on the edge of a two-dimensional electron system: We present a study of the excitations of the edge of a two-dimensional\nelectron droplet in a magnetic field in terms of a contour dynamics formalism.\nWe find that, beyond the usual linear approximation, the non-linear analysis\nyields soliton solutions which correspond to uniformly rotating shapes. These\nmodes are found from a perturbative treatment of a non-linear eigenvalue\nproblem, and as solutions to a modified Korteweg-de Vries equation resulting\nfrom a local induction approximation to the nonlocal contour dynamics. We\ndiscuss applications to the edge modes in the quantum Hall effect.",
        "positive": "Two-dimensional electron gas in a modulation-doped SrTiO3/Sr(Ti,Zr)O3\n  heterostructure: A two-dimensional electron gas (2DEG) in SrTiO3 is created via modulation\ndoping by interfacing undoped SrTiO3 with a wider-band-gap material,\nSrTi1-xZrxO3, that is doped n-type with La. All layers are grown using hybrid\nmolecular beam epitaxy. Using magnetoresistance measurements, we show that\nelectrons are transferred into the SrTiO3, and a 2DEG is formed. In particular,\nShubnikov-de Haas oscillations are shown to depend only on the perpendicular\nmagnetic field. Experimental Shubnikov-de Haas oscillations are compared with\ncalculations that assume multiple occupied subbands."
    },
    {
        "anchor": "Crossover between Strongly-coupled and Weakly-coupled Exciton\n  Superfluids: In fermionic systems, superconductivity and superfluidity are enabled through\nthe condensation of fermion pairs. The nature of this condensate can be tuned\nby varying the pairing strength, with weak coupling yielding a BCS-like\ncondensate and strong coupling resulting in a BEC-like process. However,\ndemonstration of this cross-over has remained elusive in electronic systems.\nHere we study graphene double-layers separated by an atomically thin insulator.\nUnder applied magnetic field, electrons and holes couple across the barrier to\nform bound magneto-excitons whose pairing strength can be continuously tuned by\nvarying the effective layer separation. Using temperature-dependent Coulomb\ndrag and counter-flow current measurements, we demonstrate the capability to\ntune the magneto-exciton condensate through the entire weak-coupling to\nstrong-coupling phase diagram. Our results establish magneto-exciton\ncondensates in graphene as a model platform to study the crossover between two\nBosonic quantum condensate phases in a solid state system.",
        "positive": "Optomechanical amplification driven by interference of phonon-exciton\n  and phonon-photon couplings: We study theoretically optomechanical damping and amplification spectra for\nvibrations interacting with excitonic polaritons in a zero-dimensional\nmicrocavity. We demonstrate, that the spectra strongly depend on the ratio of\nthe exciton-phonon and the photon-phonon coupling constants. The interference\nbetween these couplings enables a situation when optomechanical gain exists\neither only for a lower polaritonic resonance or only for an upper polaritonic\nresonance. Our results provide insight in the optomechanical interactions in\nvarious multi-mode systems, where several resonant oscillators, such as\nphotons, plasmons, or excitons are coupled to the same vibration mode."
    },
    {
        "anchor": "Dipole-like dynamical nuclear spin polarization around a quantum point\n  contact: We theoretically investigate the dynamical nuclear spin polarization in a\nquantum point contact (QPC) at finite magnetic field. We find that when the QPC\nis tuned to be spin selective, at the conductance of e^2/h, a finite bias\ninduces a dipole-like (spatially anti-symmetric) nuclear polarization: at the\nQPC center the polarization is zero, while, for GaAs parameters, the nuclear\nspins down (up) are induced on the source (drain) side. We predict that the\ndipole-like polarization pattern can be distinguished from a uniform\npolarization due to a qualitatively different response of the QPC conductance\nto the NMR field.",
        "positive": "Significance of nuclear quantum effects in hydrogen bonded molecular\n  chains: In hydrogen bonded systems, nuclear quantum effects such as zero-point motion\nand tunneling can significantly affect their material properties through\nunderlying physical and chemical processes. Presently, direct observation of\nthe influence of nuclear quantum effects on the strength of hydrogen bonds with\nresulting structural and electronic implications remains elusive, leaving\nopportunities for deeper understanding to harness their fascinating properties.\nWe studied hydrogen-bonded one-dimensional quinonediimine molecular networks\nwhich may adopt two isomeric electronic configurations via proton transfer.\nHerein, we demonstrate that concerted proton transfer promotes a delocalization\nof {\\pi}-electrons along the molecular chain, which enhances the cohesive\nenergy between molecular units, increasing the mechanical stability of the\nchain and giving rise to new electronic in-gap states localized at the ends.\nThese findings demonstrate the identification of a new class of isomeric\nhydrogen bonded molecular systems where nuclear quantum effects play a dominant\nrole in establishing their chemical and physical properties. We anticipate that\nthis work will open new research directions towards the control of mechanical\nand electronic properties of low-dimensional molecular materials via concerted\nproton tunneling."
    },
    {
        "anchor": "Spin Hall and spin swapping torques in diffusive ferromagnets: A complete set of the generalized drift-diffusion equations for a coupled\ncharge and spin dynamics in ferromagnets in the presence of extrinsic\nspin-orbit coupling is derived from the quantum kinetic approach, covering\nmajor transport phenomena, such as the spin and anomalous Hall effects, spin\nswapping, spin precession and relaxation processes. We argue that the spin\nswapping effect in ferromagnets is enhanced due to spin polarization, while the\noverall spin texture induced by the interplay of spin-orbital and spin\nprecessional effects displays a complex spatial dependence that can be\nexploited to generate torques and nucleate/propagate domain walls in\ncentrosymmetric geometries without use of external polarizers, as opposed to\nthe conventional understanding of spin-orbit mediated torques.",
        "positive": "Distribution of Oscillator Strengths for Recombination of Localised\n  Excitons in Two Dimensions: We investigate the distribution of oscillator strengths for the recombination\nof excitons in a two dimensional sample, trapped in local minima of the\nconfinement potential: the results are derived from a statistical topographic\nmodel of the potential. The predicted distribution of oscillator strengths is\nvery different from the Porter-Thomas disribution which usually characterises\ndisordered systems, and is notable for the fact that small oscillator strengths\nare extremely rare."
    },
    {
        "anchor": "Universal quantum control of two-electron spin quantum bits using\n  dynamic nuclear polarization: One fundamental requirement for quantum computation is to perform universal\nmanipulations of quantum bits at rates much faster than the qubit's rate of\ndecoherence. Recently, fast gate operations have been demonstrated in logical\nspin qubits composed of two electron spins where the rapid exchange of the two\nelectrons permits electrically controllable rotations around one axis of the\nqubit. However, universal control of the qubit requires arbitrary rotations\naround at least two axes. Here we show that by subjecting each electron spin to\na magnetic field of different magnitude we achieve full quantum control of the\ntwo-electron logical spin qubit with nanosecond operation times. Using a single\ndevice, a magnetic field gradient of several hundred milliTesla is generated\nand sustained using dynamic nuclear polarization of the underlying Ga and As\nnuclei. Universal control of the two-electron qubit is then demonstrated using\nquantum state tomography. The presented technique provides the basis for single\nand potentially multiple qubit operations with gate times that approach the\nthreshold required for quantum error correction.",
        "positive": "Converting Non-Equilibrium Charge Density into Spin Current: The interconversion between charge and spin degrees of freedom is of both\nfundamental and technological relevance in spintronics. While a non-equilibrium\nspin density and a charge current are related by the well known\nRashba-Edelstein effect, here we theoretically model the generation of a\ntime-dependent spin current due to a periodic modulation of the charge density,\nfor example by a gate. By using the Boltzmann transport equation, we show that\nwhen the chemical potential is varied, a spin current is generated in the time\nscale it takes for the system to re-equilibrate in the new chemical potential.\nThe effect is ubiquitous in many systems with spin-momentum locking; we compute\nthe strength of the effect in four examples and propose a simple device scheme\nto measure the spin accumulation resulting from such time-dependent spin\ncurrents. Our findings test fundamental theoretical questions about\ncharge-to-spin conversion mechanisms and provide an all-electrical way to\ngenerate spin currents without the need for charge currents, magnetic materials\nor optical methods."
    },
    {
        "anchor": "Transport across junctions of altermagnets with normal metals and\n  ferromagnets: Altermagnet (AM) is a novel time reversal symmetry broken magnetic phase with\n$d$-wave order which has been experimentally realized recently. We discuss\ntheoretical models of altermagnet based systems on lattice and in continuum. We\nshow equivalence between the lattice and continuum models by mapping the\nrespective parameters. We study (i) altermagnet-normal metal (NM) and (ii)\naltermagnet-ferromagnet (FM) junctions, with the aim to quantify transport\nproperties such as conductivity and magnetoresistance. We find that a spin\ncurrent accompanies charge current when a bias is applied. The\nmagnetoresistance of AM-FM junction switches sign when AM is rotated by\n$90^{\\circ}$ -- a feature unique to the altermagnetic phase.",
        "positive": "Spin-orbit coupling in quasi-one-dimensional Wigner crystals: We study the effect of Rashba spin-orbit coupling (SOC) on the charge and\nspin degrees of freedom of a quasi-one-dimensional (quasi-1D) Wigner crystal.\nAs electrons in a quasi-1D Wigner crystal can move in the transverse direction,\nSOC cannot be gauged away in contrast to the pure 1D case. We show that for\nweak SOC, a partial gap in the spectrum opens at certain ratios between density\nof electrons and the inverse Rashba length. We present how the low-energy\nbranch of charge degrees of freedom deviates due to SOC from its usual linear\ndependence at small wave vectors. In the case of strong SOC, we show that spin\nsector of a Wigner crystal cannot be described by an isotropic\nantiferromagnetic Heisenberg Hamiltonian any more, and that instead the ground\nstate of neighboring electrons is mostly a triplet state. We present a new spin\nsector Hamiltonian and discuss the spectrum of Wigner crystal in this limit."
    },
    {
        "anchor": "Interference effects and Huygens' principle in transverse magnetic\n  focusing of electrons and holes: Interference effects form a fundamental pillar of quantum mechanics. In this\npaper, we examine the interference in spin-orbit coupled transverse magnetic\nfocusing, where a weak magnetic field is used to focus charge carries over\nmesoscopic scales. We determine a semi-classical form for the Green's function\nin a weak magnetic field, for the case of both spin-less and spin-orbit coupled\ncharge carriers. The obtained forms for the Greens' function are independent of\nparticle dispersion and are thus applicable to a wide variety of systems.",
        "positive": "Comment on \"Sticking of Hydrogen on Supported and Suspended Graphene at\n  Low Temperature\": The sticking probability of cold atomic hydrogen on suspended graphene\ncalculated by Lepetit and Jackson [Phys. Rev. Lett. {\\bf 107}, 236102 (2011)]\ndoes not include the effect of fluctuations from low-frequency vibrations of\ngraphene. These fluctuations suppress the sticking probability for low incident\nenergies ($\\lesssim 15$ meV)."
    },
    {
        "anchor": "Topological axion states in magnetic insulator MnBi$_2$Te$_4$ with the\n  quantized magnetoelectric effect: Topological states of quantum matter have attracted great attention in\ncondensed matter physics and materials science. The study of\ntime-reversal-invariant (TRI) topological states in quantum materials has made\ntremendous progress in both theories and experiments. As a great success,\nthousands of TRI topological materials are predicted through sweeping search.\nRicher exotic phenomena are expected to appear in magnetic topological\nmaterials because of varied magnetic configurations, but this study falls much\nbehind due to the complex magnetic structures and transitions. Here, we predict\nthe tetradymite-type compound MnBi$_2$Te$_4$ and its related materials host\ninteresting magnetic topological states. The magnetic ground state of\nMnBi$_2$Te$_4$ is an antiferromagnetic phase which leads to an antiferromagetic\ntopological insulator state with a large topologically non-trivial energy gap\n($\\sim$0.2~eV). It is the parent state for the axion state, which has gapped\nbulk and surface states, and quantized topological magnetoelectric effect. The\nferromagnetic phase of MnBi$_2$Te$_4$ leads to an ideal minimal type-II Weyl\nsemimetal with two Weyl points accompanied by one hole-type and one\nelectron-type Fermi pocket at the Fermi level, which has never been discovered\nelsewhere. We further present a simple and unified continuum model to capture\nthe salient topological features of this kind of materials.",
        "positive": "Seeing Quantum Fractals: This Perspectives article highlights some of the interesting features and\nopen questions presented by recent scanning tunneling microscope (STM)\nexperiments on GaMnAs near the metal-insulator transition."
    },
    {
        "anchor": "Non-Equilibrium First-Order Exciton Mott Transition at Monolayer Lateral\n  Heterojunctions Visualized by Ultrafast Microscopy: Atomically precise lateral heterojunctions based on transition metal\ndichalcogenides provide a new platform for exploring exciton Mott transition in\none-dimension. To investigate the intrinsically non-equilibrium Mott\ntransition, we employed ultrafast microscopy with ~ 200 fs temporal resolution\nto image the transport of different exciton phases in a type II\nWSe2-WS1.16Se0.84 lateral heterostructure. These measurements visualized the\nextremely rapid expansion of a highly non-equilibrium electron-hole (e-h)\nplasma phase with a Fermi velocity up to 3.2*10^6 cm*s-1. An abrupt first-order\nexciton Mott transition at a density of ~ 5*10^12 cm-2 at room temperature was\nrevealed by ultrafast microscopy, which could be disguised as a continuous\ntransition in conventional steady-state measurements. These results point to\nexciting new opportunities for designing atomically thin lateral\nheterojunctions as novel highways of excitons and collective e-h plasma for\nhigh-speed electronic applications.",
        "positive": "Fermi level tuning of one-dimensional giant Rashba system on a\n  semiconductor substrate: Bi/GaSb(110)-(2x1): We fabricated spin-polarized surface electronic states with tunable Fermi\nlevel from semiconductor to low-dimensional metal in the\nBi/GaSb(110)-(2$\\times$1) surface using angle-resolved photoelectron\nspectroscopy (ARPES) and spin-resolved ARPES. The spin-polarized surface band\nof Bi/GaSb(110) exhibits quasi-one-dimensional character with the Rashba\nparameter $\\alpha _{\\rm R}$ of 4.1 and 2.6 eV\\AA \\ at the $\\bar{\\Gamma}$ and\n$\\bar{\\rm Y}$ points of the surface Brillouin zone, respectively. The Fermi\nlevel of the surface electronic state is tuned in situ by element-selective\nAr-ion sputtering on the GaSb substrate. The giant Rashba-type spin splitting\nwith switchable metallic/semiconducting character on semiconductor substrate\nmakes this system a promising candidate for future researches in\nlow-dimensional spintronic phenomena."
    },
    {
        "anchor": "Electronic spectra of commensurate and incommensurate DWNTs in parallel\n  magnetic field: We study the electronic spectra of commensurate and incommensurate\ndouble-wall carbon nanotubes (DWNTs) of finite length. The coupling between\nnanotube shells is taken into account as an intershell electron tunneling.\nSelection rules for the intershell coupling are derived. Due to the finite size\nof the system, these rules do not represent exact conservation of the crystal\nmomentum, but only an approximate one; therefore the coupling between\nlongitudinal momentum states in incommensurate DWNTs becomes possible. The use\nof the selection rules allows a fast and efficient calculation of the\nelectronic spectrum. In the presence of a magnetic field parallel to the DWNT\naxis we find spectrum modulations which depend on the chiralities of the\nshells.",
        "positive": "From mesoscopic magnetism to the anomalous 0.7 conductance plateau: We present a simple phenomenological model which offers a unifying\ninterpretation of the experimental observations on the 0.7 conductance anomaly\nof quantum point contacts. The model utilizes the Landauer-Buttiker formalism\nand involves enhanced spin correlations and thermal depopulation of spin\nsubbands. In particular our model can account for the plateau value 0.7 and the\nunusual temperature and magnetic field dependence. Furthermore it predicts an\nanomalous suppression of shot noise at the 0.7 plateau."
    },
    {
        "anchor": "Magnetoconductivity of type-II Weyl semimetals: Type-II Weyl semimetals are characterized by the tilted linear dispersion in\nthe low-energy excitations, mimicking Weyl fermions but with manifest violation\nof the Lorentz invariance, which has intriguing quantum transport properties.\nThe magnetoconductivity of type-II Weyl semimetals is investigated numerically\nbased on lattice models in parallel electric and magnetic field. We show that\nin the high-field regime, the sign of the magnetoconductivity of an\ninversion-symmetry-breaking type-II Weyl semimetals depends on the direction of\nthe magnetic field, whereas in the weak field regime, positive\nmagnetoconductivity is always obtained regardless of magnetic field direction.\nWe find that the weak localization is sensitive to the spatial extent of\nimpurity potential. In time-reversal symmetry breaking type-II Weyl semimetals,\nthe system displays either positive or negative magnetoconductivity along the\ndirection of band tilting, owing to the associated effect of group velocity,\nBerry curvature and the magnetic field.",
        "positive": "Observation of Spin Hall Effect in Weyl Semimetal WTe2 at Room\n  Temperature: Discovery of topological Weyl semimetals has revealed the opportunities to\nrealize several extraordinary physical phenomena in condensed matter physics.\nSpecifically, these semimetals with strong spin-orbit coupling, broken\ninversion symmetry and novel spin texture are predicted to exhibit a large spin\nHall effect that can efficiently convert the charge current to a spin current.\nHere we report the direct experimental observation of a large spin Hall and\ninverse spin Hall effects in Weyl semimetal WTe2 at room temperature obeying\nOnsager reciprocity relation. We demonstrate the detection of the pure spin\ncurrent generated by spin Hall phenomenon in WTe2 by making van der Waals\nheterostructures with graphene, taking advantage of its long spin coherence\nlength and spin transmission at the heterostructure interface. These\nexperimental findings well supported by ab initio calculations show a large\ncharge-spin conversion efficiency in WTe2; which can pave the way for\nutilization of spin-orbit induced phenomena in spintronic memory and logic\ncircuit architectures."
    },
    {
        "anchor": "Band warping, band non-parabolicity and Dirac points in fundamental\n  lattice and electronic structures: We demonstrate from a fundamental perspective the physical and mathematical\norigins of band warping and band non-parabolicity in electronic and vibrational\nstructures. Remarkably, we find a robust presence and connection with pairs of\ntopologically induced Dirac points in a primitive-rectangular lattice using a\n$p$-type tight-binding approximation. We provide a transparent analysis of\ntwo-dimensional primitive-rectangular and square Bravais lattices whose basic\nimplications generalize to more complex structures. Band warping typically\narises at the onset of a singular transition to a crystal lattice with a larger\nsymmetry group, suddenly allowing the possibility of irreducible\nrepresentations of higher dimensions at special symmetry points in reciprocal\nspace. Band non-parabolicities are altogether different higher-order features,\nalthough they may merge into band warping at the onset of a larger symmetry\ngroup. Quite separately, although still maintaining a clear connection with\nthat merging, band non-parabolicities may produce pairs of conical\nintersections at relatively low-symmetry points. Apparently, such conical\nintersections are robustly maintained by global topology requirements, rather\nthan any local symmetry protection. For two $p$-type tight-binding bands, we\nfind such pairs of conical intersections drifting along the edges of restricted\nBrillouin zones of primitive-rectangular Bravais lattices as lattice constants\nvary relatively, until they merge into degenerate warped bands at high-symmetry\npoints at the onset of a square lattice. The conical intersections that we\nfound appear to have similar topological characteristics as Dirac points\nextensively studied in graphene and other topological insulators, although our\nconical intersections have none of the symmetry complexity and protection\nafforded by the latter more complex structures.",
        "positive": "A Nonlinear HP-Type Complementary Resistive Switch: Resistive Switching (RS) is the change in resistance of a dielectric under\nthe influence of an external current or electric field. This change is\nnon-volatile, and the basis of both the memristor and resistive random access\nmemory. In the latter, high integration densities favor the anti-serial\ncombination of two RS-elements to a single cell, termed the complementary\nresistive switch (CRS). Motivated by the irregular shape of the filament\nprotruding into the device, we suggest a nonlinearity in the\nresistance-interpolation function, and thereby expand the original\nHP-memristor. We numerically simulate and analytically solve this model.\nFurther, the nonlinearity allows for its application to the CRS."
    },
    {
        "anchor": "Characterizing the Quantum Confined Stark Effect in Semiconductor\n  Quantum Dots and Nanorods for Single-Molecule Electrophysiology: We optimized the performance of quantum confined Stark effect QCSE based\nvoltage nanosensors. A high throughput approach for single particle QCSE\ncharacterization was developed and utilized to screen a library of such\nnanosensors. Type II ZnSe CdS seeded nanorods were found to have the best\nperformance among the different nanosensors evaluated in this work. The degree\nof correlation between intensity changes and spectral changes of the excitons\nemission under applied field was characterized. An upper limit for the temporal\nresponse of individual ZnSe CdS nanorods to voltage modulation was\ncharacterized by high throughput, high temporal resolution intensity\nmeasurements using a novel photon counting camera. The measured 3.5 us response\ntime is limited by the voltage modulation electronics and represents about 30\ntimes higher bandwidth than needed for recording an action potential in a\nneuron.",
        "positive": "Oxygen clamps in gold nanowires: We investigate how the insertion of an oxygen atom in an atomically thin gold\nnanowire can affect its rupture. We find, using ab initio total energy density\nfunctional theory calculations, that O atoms when inserted in gold nanowires\nform not only stable but also very strong bonds, in such a way that they can\nextract atoms from a stable tip, serving in this way as a clamp that could be\nused to pull a string of gold atoms."
    },
    {
        "anchor": "A variant transfer matrix method suitable for transport through\n  multi-probe systems: We have developed a variant transfer matrix method that is suitable for\ntransport through multi-probe systems. Using this method, we have numerically\nstudied the quantum spin Hall effect (QSHE) on 2D graphene with both intrinsic\n(Vso) and Rashba (Vr) spin-orbit (SO) couplings. The integer QSHE arises in the\npresence of intrinsic SO interaction and is gradually destroyed by the Rashba\nSO interaction and disorder fluctuation. We have numerically determined the\nphase boundaries separating integer QSHE and spin Hall liquid. We have found\nthat when Vso> 0.2t with t the hopping constant the energy gap needed for the\ninteger QSHE is the largest satisfying |E|<t. For smaller Vso the energy gap\ndecreases linearly. In the presence of Rashba SO interaction or disorders, the\nenergy gap diminishes. With Rashba SO interaction the integer QSHE is robust at\nthe largest energy within the energy gap while at the smallest energy within\nthe energy gap the integer QSHE is insensitive to the disorder.",
        "positive": "Large Tunneling Anisotropic Magneto-Seebeck Effect in a CoPt|MgO|Pt\n  Tunnel Junction: We theoretically investigate the Tunneling Anisotropic Magneto-Seebeck effect\nin a realistically-modeled CoPt|MgO|Pt tunnel junction using coherent transport\ncalculations. For comparison we study the tunneling magneto-Seebeck effect in\nCoPt|MgO|CoPt as well. We find that the magneto-Seebeck ratio of CoPt|MgO|Pt\nexceeds that of CoPt|MgO|CoPt for small barrier thicknesses, reaching 175% at\nroom temperature. This result provides a sharp contrast to the\nmagnetoresistance, which behaves oppositely for all barrier thicknesses and\ndiffers by one order of magnitude between devices. Here the magnetoresistance\nresults from differences in transmission brought upon by changing the tunnel\njunction's magnetization configuration. The magneto-Seebeck effect results from\nvariations in asymmetry of the energy-dependent transmission instead. We report\nthat this difference in origin allows for CoPt|MgO|Pt to possess strong thermal\nmagnetic-transport anisotropy."
    },
    {
        "anchor": "Dynamics of Anderson localization in disordered wires: We consider the dynamics of an electron in an infinite disordered metallic\nwire. We derive exact expressions for the probability of diffusive return to\nthe starting point in a given time. The result is valid for wires with or\nwithout time-reversal symmetry and allows for the possibility of topologically\nprotected conducting channels. In the absence of protected channels, Anderson\nlocalization leads to a nonzero limiting value of the return probability at\nlong times, which is approached as a negative power of time with an exponent\ndepending on the symmetry class. When topologically protected channels are\npresent (in a wire of either unitary or symplectic symmetry), the probability\nof return decays to zero at long time as a power law whose exponent depends on\nthe number of protected channels. Technically, we describe the electron\ndynamics by the one-dimensional supersymmetric non-linear sigma model. We\nderive an exact identity that relates any local dynamical correlation function\nin a disordered wire of unitary, orthogonal, or symplectic symmetry to a\ncertain expectation value in the random matrix ensemble of class AIII, CI, or\nDIII, respectively. The established exact mapping from one- to zero-dimensional\nsigma model is very general and can be used to compute any local observable in\na disordered wire.",
        "positive": "Fine structure of neutral acceptor states of isolated impurity in\n  zinc-blende semiconductors: The properties of neutral acceptor states in zinc-blende semiconductors are\nre-examined in the frame of extended-basis $sp^3d^5s^*$ tight-binding model.\nThe symmetry discrepancy between envelope function theory and atomistic\ncalculations is explained in terms of over symmetric potential in current\nk$\\cdot$p approaches. Spherical harmonics decomposition of microscopic Local\nDensity Of States (LDOS) allows for the direct analysis of the tight-binding\nresults in terms of envelope function. Lifting of degeneracy by strain and\nelectric field and their effect on LDOS is examined. The fine structure of\nmagnetic impurity caused by exchange interaction of hole with impurity\n$d$-shell and its dependence on strain is studied. It is shown that exchange\ninteraction by mixing heavy and light hole makes the ground state more\nisotropic. The results are important in the context of Scanning Tunneling\nMicroscopy (STM) images of subsurface impurities."
    },
    {
        "anchor": "Exact scattering eigenstates, many-body bound states, and nonequilibrium\n  current of an open quantum dot system: We obtain an exact many-body scattering eigenstate in an open quantum dot\nsystem. The scattering state is not in the form of the Bethe eigenstate in the\nsense that the wave-number set of the incoming plane wave is not conserved\nduring the scattering and many-body bound states appear. By using the\nscattering state, we study the average nonequilibrium current through the\nquantum dot under a finite bias voltage. The current-voltage characteristics\nthat we obtained by taking the two-body bound state into account is\nqualitatively similar to several known results.",
        "positive": "Universal spin-induced Time Reversal Symmetry breaking in\n  two-dimensional electron gases with Rashba spin-orbit interaction: We have experimentally studied the spin-induced time reversal symmetry (TRS)\nbreaking as a function of the relative strength of the Zeeman energy (E_Z) and\nthe Rashba spin-orbit interaction energy (E_SOI), in InGaAs-based 2D electron\ngases. We find that the TRS breaking saturates when E_Z becomes comparable to\nE_SOI. Moreover, we show that the spin-induced TRS breaking mechanism is a\nuniversal function of the ratio E_Z/E_SOI, within the experimental accuracy."
    },
    {
        "anchor": "The effects of disorder and interactions on the Anderson transition in\n  doped Graphene: We undertake an exact numerical study of the effects of disorder on the\nAnderson localization of electronic states in graphene. Analyzing the scaling\nbehaviors of inverse participation ratio and geometrically averaged density of\nstates, we find that Anderson metal-insulator transition can be introduced by\nthe presence of quenched random disorder. In contrast with the conventional\npicture of localization, four mobility edges can be observed for the honeycomb\nlattice with specific disorder strength and impurity concentration. Considering\nthe screening effects of interactions on disorder potentials, the experimental\nfindings of the scale enlarges of puddles can be explained by reviewing the\neffects of both interactions and disorder.",
        "positive": "Collective Modes and Skyrmion Excitations in Graphene SU(4) Quantum Hall\n  Ferromagnets: Graphene exhibits quantum Hall ferromagnetism in which an approximate SU(4)\nsymmetry involving spin and valley degrees of freedom is spontaneously broken.\nWe construct a set of integer and fractional quantum Hall states that break the\nSU(4) spin/valley symmetry, and study their neutral and charged excitations.\nSeveral properties of these ferromagnets can be evaluated analytically in the\nSU(4) symmetric limit, including the full collective mode spectrum at integer\nfillings. By constructing explicit wave functions we show that the lowest\nenergy skyrmion states carry charge $\\pm 1$ for {\\em any} integer filling, and\nthat skyrmions are the lowest energy charged excitations for graphene Landau\nlevel index $|n| \\le 3$. We also show that the skyrmion lattice states which\noccur near integer filling factors support four gapless collective mode\nbranches in the presence of full SU(4) symmetry. Comparisons are made with the\nmore familiar SU(2) quantum Hall ferromagnets studied previously."
    },
    {
        "anchor": "Adhesion, Stiffness and Instability in Atomically Thin MoS2 Bubbles: We measured the work of separation of single and few-layer MoS2 membranes\nfrom a SiOx substrate using a mechanical blister test, and found a value of 220\n+- 35 mJ/m^2. Our measurements were also used to determine the 2D Young's\nmodulus of a single MoS2 layer to be 160 +- 40 N/m. We then studied the\ndelamination mechanics of pressurized MoS2 bubles, demonstrating both stable\nand unstable transitions between the bubbles' laminated and delaminated states\nas the bubbles were inflated. When they were deflated, we observed edge pinning\nand a snap-in transition which are not accounted for by the previously reported\nmodels. We attribute this result to adhesion hysteresis and use our results to\nestimate the work of adhesion of our membranes to be 42 +- 20 mJ/m^2.",
        "positive": "Thermal Enhancement of Interference Effects in Quantum Point Contacts: We study an electron interferometer formed with a quantum point contact and a\nscanning probe tip in a two-dimensional electron gas. The images giving the\nconductance as a function of the tip position exhibit fringes spaced by half\nthe Fermi wavelength. For a contact opened at the edges of a quantized\nconductance plateau, the fringes are enhanced as the temperature T increases\nand can persist beyond the thermal length l_T. This unusual effect is explained\nassuming a simplified model: The fringes are mainly given by a contribution\nwhich vanishes when T -> 0 and has a decay characterized by a T-independent\nscale."
    },
    {
        "anchor": "Electron-beam patterning of polymer electrolyte films to make multiple\n  nanoscale gates for nanowire transistors: We report an electron-beam based method for the nanoscale patterning of the\npoly(ethylene oxide)/LiClO$_{4}$ polymer electrolyte. We use the patterned\npolymer electrolyte as a high capacitance gate dielectric in single nanowire\ntransistors and obtain subthreshold swings comparable to conventional\nmetal/oxide wrap-gated nanowire transistors. Patterning eliminates gate/contact\noverlap which reduces parasitic effects and enables multiple, independently\ncontrollable gates. The method's simplicity broadens the scope for using\npolymer electrolyte gating in studies of nanowires and other nanoscale devices.",
        "positive": "Exact analytical solutions for tilted anisotropic Dirac materials. An\n  easy algorithm?: In this article, we obtain the exact solutions for bound states of tilted\nanisotropic Dirac materials under the action of external electric and magnetic\nfields with translational symmetry. In order to solve the eigenvalue equation\nthat arises from the effective Hamiltonian of these materials, we describe an\nalgorithm that allow us to decouple the differential equations that are\nobtained for the spinor components."
    },
    {
        "anchor": "Ultrafast modulation of near-field heat transfer with tunable\n  metamaterials: We propose a mechanism of active near-field heat transfer modulation relying\non externally tunable metamaterials. A large modulation effect is observed and\ncan be explained by the coupling of surface modes, which is dramatically varied\nin the presence of controllable magnetoelectric coupling in metamaterials. We\nfinally discuss how a practical picosecond-scale thermal modulator can be made.\nThis modulator allows manipulating nanoscale heat flux in an ultrafast and\nnoncontact (by optical means) manner.",
        "positive": "Exciton interaction induced spin splitting in MoS$_2$ monolayer: By pumping nonresonantly a MoS$_2$ monolayer at $13$ K under a circularly\npolarized cw laser, we observe exciton energy redshifts that break the\ndegeneracy between B excitons with opposite spin. The energy splitting\nincreases monotonically with the laser power reaching as much as $18$ meV,\nwhile it diminishes with the temperature. The phenomenon can be explained\ntheoretically by considering simultaneously the bandgap renormalization which\ngives rise to the redshift and exciton-exciton Coulomb exchange interaction\nwhich is responsible for the spin-dependent splitting. Our results offer a\nsimple scheme to control the valley degree of freedom in MoS$_2$ monolayer and\nprovide an accessible method in investigating many-body exciton exciton\ninteraction in such materials."
    },
    {
        "anchor": "Scaling analysis of Schottky barriers at metal-embedded semiconducting\n  carbon nanotube interfaces: We present an atomistic self-consistent tight-binding study of the electronic\nand transport properties of metal-semiconducting carbon nanotube interfaces as\na function of the nanotube channel length when the end of the nanotube wire is\nburied inside the electrodes. We show that the lineup of the nanotube band\nstructure relative to the metal Fermi-level depends strongly on the metal work\nfunction but weakly on the details of the interface. We analyze the\nlength-dependent transport characteristics, which predicts a transition from\ntunneling to thermally-activated transport with increasing nanotube channel\nlength.",
        "positive": "Critical behavior of nanocrystalline gadolinium: Evidence for a new\n  universality class: We report on how nanocrystal size affects the critical behavior of the\nrare-earth metal Gd near the ferromagnetic-to-paramagnetic phase transition.\nThe asymptotic critical behavior of the coarse-grained polycrystalline sample\n(with an average crystallite size of $L \\cong \\unit[100]{\\mu m}$) is that of a\n(pure) \\textsl{uniaxial dipolar} ferromagnet, as is the case with\nsingle-crystal Gd, albeit the width of the asymptotic critical region (ACR) is\nreduced. As the grain size approaches $\\sim \\unit[30]{nm}$, the ACR is so\nnarrow that it could not be accessed in the present experiments. Inaccessibly\nnarrow ACR for $L \\sim \\unit[30]{nm}$ and the continuous increase in the width\nof ACR as $L$ decreases from $\\unit[16]{nm}$ to $\\unit[9.5]{nm}$ basically\nreflects a crossover to the \\textsl{random uniaxial dipolar} fixed point caused\nby the quenched random-exchange disorder prevalent at the internal interfaces\n(grain boundaries)."
    },
    {
        "anchor": "Collective excitations of a system of coupled relativistic and\n  non-relativistic two-dimensional electron gases: We study collective excitations of a two-dimensional electron system\nconsisting of two kinds of charge carriers: relativistic or Dirac electrons\nwith linear dispersion and non-relativistic electrons with parabolic\ndispersion. We find that the strength of the interaction between the different\ncharge carriers, i.e., the inter-species interaction, plays a significant role\nin determining the number of plasmon modes as well as their dispersions in\ncertain parameter regimes.",
        "positive": "Engineering ideal helical topological networks in stanene via Zn\n  decoration: The xene family of topological insulators plays a key role in many proposals\nfor topological electronic, spintronic, and valleytronic devices. These\nproposals rely on applying local perturbations, including electric fields and\nproximity magnetism, to induce topological phase transitions in xenes. However,\nthese techniques lack control over the geometry of interfaces between\ntopological regions, a critical aspect of engineering topological devices. We\npropose adatom decoration as a method for engineering atomically precise\ntopological edge modes in xenes. Our first-principles calculations show that\ndecorating stanene with Zn adatoms exclusively on one of two sublattices\ninduces a topological phase transition from the quantum spin Hall (QSH) to\nquantum valley Hall (QVH) phase and confirm the existence of spin-valley\npolarized edge modes propagating at QSH/QVH interfaces. We conclude by\ndiscussing technological applications of these edge modes that are enabled by\nthe atomic precision afforded by recent advances in adatom manipulation\ntechnology."
    },
    {
        "anchor": "Antiferromagnetic Metal Spintronics: Spintronics in ferromagnetic metals is built on a complementary set of\nphenomena in which magnetic configurations influence transport coefficients and\ntransport currents alter magnetic configurations. In this Letter we propose\nthat corresponding effects occur in circuits containing antiferromagnetic\nmetals. The critical current for switching can be smaller in the\nantiferromagnetic case because of the absence of shape anisotropy and because\nspin torques act through the entire volume of an antiferromagnet. Our findings\nsuggest that current-induced order parameter dynamics can be used to coarsen\nthe microstructure of antiferromagnetic thin films.",
        "positive": "Shot noise in resonant tunneling: Role of inelastic scattering: We study the influence of inelastic processes on shot noise and the Fano\nfactor for a one-dimensional double-barrier structure, where resonant tunneling\ntakes place between two terminals. Most studies to date have found, by means of\nvarious approximate or phenomenological methods, that shot noise is insensitive\nto dephasing caused by inelastic scattering. In this paper, we explore the\nstatus of this statement by deriving a general Landaur-B\\\"uttiker-type formula\nthat expresses the current noise and Fano factor in a one-dimensional conductor\nthrough inelastic scattering amplitudes. For a double-barrier structure, exact\nscattering amplitudes are calculated in the presence of a time-dependent\npotential. As an example of dephasing potential, we consider the one induced by\nequilibrium phonons. We calculate transmission coefficients of a double-barrier\nstructure for these two types of phonon-induced dephasing. In the case of\ndiffusive phase relaxation valid for one dimension phonons, the resonant level\nhas a Lorentzian shape. For phonons whith high dimensions logarithmic dephasing\nrealized which leads to an unusual shape of the size-quantized level\ncharacterized by the two energy scales. We further calculate the Fano factor\nfor these types of dephasing, using exact expressions for inelastic\ntransmission and reflection amplitudes. It turned out that when an integer\nnumber of levels fall into the energy window of width eV, where V is the\nvoltage applied to the structure, the Fano factor is really insensitive to\ninelastic processes inside the structure and coincides with the prediction of\nphenomenological models with an accuracy of small corrections depending on\nthese processes. On the contrary, at low voltages, when the eV window is\nsmaller than the level width, this dependence is particularly pronounced and\nthe phenomenological formula does not work."
    },
    {
        "anchor": "Dielectric Hysteresis, Relaxation Dynamics, and Non-volatile Memory\n  Effect in Carbon Nanotube Dispersed Liquid Crystal: The self-organizing properties of nematic liquid crystals (LC) can be used to\ntemplate carbon nanotubes (CNTs) on a macroscopic dimension. The nematic\ndirector field, coupled to the dispersed CNT long-axis, enables controlled\ndirector reorientation using well-established methods of LC alignment\ntechniques, such as patterned-electrode-surface, electric fields, and magnetic\nfields. Electric field induced director rotation of a nematic LC+CNT system is\nof potential interests due to its possible applications as a nano\nelectromechanical system. The relaxation mechanism for a LC+CNT composite, on\nthe removal of the applied field, reveals the intrinsic dynamics of this\nanisotropic system. Dielectric hysteresis and temperature dependence of the\ndielectric constant coherently shows the ferroelectric-type behavior of the\nLC+CNT system in the nematic phase. The strong surface anchoring of LC\nmolecules on CNT walls results in forming local isolated pseudo-nematic domains\nin the isotropic phase. These domains, being anisotropic, respond to external\nfields, but, do not relax back to the original state on switching of the field\noff, showing non-volatile memory effect.",
        "positive": "Magnetic Phases of Bilayer Quantum-Dot Hubbard Model Plaquettes: It has been demonstrated that small plaquettes of quantum dot spin qubits are\ncapable of simulating condensed matter phenomena which arise from the Hubbard\nmodel, such as the collective Coulomb blockade and Nagaoka ferromagnetism.\nMotivated by recent materials developments, we investigate a bilayer\narrangement of quantum dots with four dots in each layer which exhibits a\ncomplex ground state behavior. We find using a generalized Hubbard model with\nlong-range Coulomb interactions, several distinct magnetic phases occur as the\nCoulomb interaction strength is varied, with possible ground states that are\nferromagnetic, antiferromagnetic, or having both one antiferromagnetic and one\nferromagnetic layer. We map out the full phase diagram of the system as it\ndepends on the inter- and intra-layer Coulomb interaction strengths, and find\nthat for a single layer, a similar but simpler effect occurs. We also predict\ninteresting contrasts among electron, hole, and electron-hole bilayer systems\narising from complex correlation physics. Observing the predicted magnetic\nconfiguration in already-existing few-dot semiconductor bilayer structures\ncould prove to be an important assessment of current experimental quantum dot\ndevices, particularly in the context of spin-qubit-based analog quantum\nsimulations."
    },
    {
        "anchor": "Marginal topological properties of graphene: a comparison with\n  topological insulators: The electronic structures of graphene systems and topological insulators have\nclosely-related features, such as quantized Berry phase and zero-energy edge\nstates. The reason for these analogies is that in both systems there are two\nrelevant orbital bands, which generate the pseudo-spin degree of freedom, and,\nless obviously, there is a correspondence between the valley degree of freedom\nin graphene and electron spin in topological insulators. Despite the\nsimilarities, there are also several important distinctions, both for the bulk\ntopological properties and for their implications for the edge states --\nprimarily due to the fundamental difference between valley and spin. In view of\ntheir peculiar band structure features, gapped graphene systems should be\nproperly characterized as marginal topological insulators, distinct from either\nthe trivial insulators or the true topological insulators.",
        "positive": "Encapsulation and Electronic Control of Epitaxial Graphene by\n  Photosensitive Polymers and UV light: Electronic devices using epitaxial graphene on Silicon Carbide require\nencapsulation to avoid uncontrolled doping by impurities deposited in ambient\nconditions. Additionally, interaction of the graphene monolayer with the\nsubstrate causes relatively high level of electron doping in this material,\nwhich is rather difficult to change by electrostatic gating alone.\n  Here we describe one solution to these problems, allowing both encapsulation\nand control of the carrier concentration in a wide range. We describe a novel\nheterostructure based on epitaxial graphene grown on silicon carbide combined\nwith two polymers: a neutral spacer and a photoactive layer that provides\npotent electron acceptors under UV light exposure. Unexposed, the same double\nlayer of polymers works well as capping material, improving the temporal\nstability and uniformity of the doping level of the sample. By UV exposure of\nthis heterostructure we controlled electrical parameters of graphene in a\nnon-invasive, non-volatile, and reversible way, changing the carrier\nconcentration by a factor of 50. The electronic properties of the exposed SiC/\ngraphene/polymer heterostructures remained stable over many days at room\ntemperature, but heating the polymers above the glass transition reversed the\neffect of light.\n  The newly developed photochemical gating has already helped us to improve the\nrobustness (large range of quantizing magnetic field, substantially higher\nopera- tion temperature and significantly enhanced signal-to-noise ratio due to\nsignificantly increased breakdown current) of a graphene resistance standard to\nsuch a level that it starts to compete favorably with mature semiconductor\nheterostructure standards. [2,3]"
    },
    {
        "anchor": "Ultrafast electronic heat dissipation through surface-to-bulk Coulomb\n  coupling in quantum materials: The timescale of electronic cooling is an important parameter controlling the\nperformance of devices based on quantum materials for optoelectronic,\nthermoelectric and thermal management applications. In most conventional\nmaterials, cooling proceeds via the emission of phonons, a relatively slow\nprocess that can bottleneck the carrier relaxation dynamics, thus degrading the\ndevice performance. Here we present the theory of near-field radiative heat\ntransfer, that occurs when a two-dimensional electron system is coupled via the\nnon-retarded Coulomb interaction to a three-dimensional bulk that can behave as\na very efficient electronic heat sink. We apply our theory to study the cooling\ndynamics of surface states of three dimensional topological insulators, and of\ngraphene in proximity to small-gap bulk materials. The ``Coulomb cooling'' we\nintroduce is alternative to the conventional phonon-mediated cooling, can be\nvery efficient and dominate the cooling dynamics under certain circumstances.\nWe show that this cooling mechanism can lead to a sub-picosecond time scale,\nsignificantly faster than the cooling dynamics normally observed in Dirac\nmaterials.",
        "positive": "Few-electron Single and Double Quantum Dots in an InAs Two-Dimensional\n  Electron Gas: Most proof-of-principle experiments for spin qubits have been performed using\nGaAs-based quantum dots because of the excellent control they offer over\ntunneling barriers and the orbital and spin degrees of freedom. Here, we\npresent the first realization of high-quality single and double quantum dots\nhosted in an InAs two-dimensional electron gas (2DEG), demonstrating accurate\ncontrol down to the few-electron regime, where we observe a clear Kondo effect\nand singlet-triplet spin blockade. We measure an electronic $g$-factor of $16$\nand a typical magnitude of the random hyperfine fields on the dots of $\\sim\n0.6\\, \\mathrm{mT}$. We estimate the spin-orbit length in the system to be $\\sim\n5-10\\, \\mu \\mathrm{m}$, which is almost two orders of magnitude longer than\ntypically measured in InAs nanostructures, achieved by a very symmetric design\nof the quantum well. These favorable properties put the InAs 2DEG on the map as\na compelling host for studying fundamental aspects of spin qubits. Furthermore,\nhaving weak spin-orbit coupling in a material with a large Rashba coefficient\npotentially opens up avenues for engineering structures with spin-orbit\ncoupling that can be controlled locally in space and/or time."
    },
    {
        "anchor": "The impact of stochastic incorporation on atomic-precision Si:P arrays: Scanning tunneling microscope lithography can be used to create\nnanoelectronic devices in which dopant atoms are precisely positioned in a Si\nlattice within $\\sim$1 nm of a target position. This exquisite precision is\npromising for realizing various quantum technologies. However, a potentially\nimpactful form of disorder is due to incorporation kinetics, in which the\nnumber of P atoms that incorporate into a single lithographic window is\nmanifestly uncertain. We present experimental results indicating that the\nlikelihood of incorporating into an ideally written three-dimer single-donor\nwindow is $63 \\pm 10\\%$ for room-temperature dosing, and corroborate these\nresults with a model for the incorporation kinetics. Nevertheless, further\nanalysis of this model suggests conditions that might raise the incorporation\nrate to near-deterministic levels. We simulate bias spectroscopy on a chain of\ncomparable dimensions to the array in our yield study, indicating that such an\nexperiment may help confirm the inferred incorporation rate.",
        "positive": "Transport properties of a periodically driven superconducting single\n  electron transistor: We discuss coherent transport of Cooper pairs through a Cooper pair shuttle.\nWe analyze both the DC and AC Josephson effect in the two limiting cases where\nthe charging energy $E_C$ is either much larger or much smaller than the\nJosephson coupling $E_J$. In the limit $E_J \\ll E_C$ we present the detailed\nbehavior of the critical current as a function of the damping rates and the\ndynamical phases. The AC effect in this regime is very sensitive to all\ndynamical scales present in the problem. The effect of fluctuations of the\nexternal periodic driving is discussed as well. In the opposite regime the\nsystem can be mapped onto the quantum kicked rotator, a classically chaotic\nsystem. We investigate the transport properties also in this regime showing\nthat the underlying classical chaotic dynamics emerges as an incoherent\ntransfer of Cooper pairs through the shuttle. For an appropriate choice of the\nparameters the Cooper pair shuttle can exhibit the phenomenon of dynamical\nlocalization. We discuss in details the properties of the localized regime as a\nfunction of the phase difference between the superconducting electrodes and the\ndecoherence due to gate voltage fluctuations. Finally we point how dynamical\nlocalization is reflected in the noise properties of the shuttle."
    },
    {
        "anchor": "Imaging high-speed friction at the nanometer scale: Friction is a complicated phenomenon involving nonlinear dynamics at\ndifferent length and time scales[1, 2]. The microscopic origin of friction is\npoorly understood, due in part to a lack of methods for measuring the force on\na nanometer-scale asperity sliding at velocity of the order of cm/s.[3, 4]\nDespite enormous advance in experimental techniques[5], this combination of\nsmall length scale and high velocity remained illusive. Here we present a\ntechnique for rapidly measuring the frictional forces on a single asperity (an\nAFM tip) over a velocity range from zero to several cm/s. At each image pixel\nwe obtain the velocity dependence of both conservative and dissipative forces,\nrevealing the transition from stick-slip to a smooth sliding friction[1, 6]. We\nexplain measurements on graphite using a modified Prandtl-Tomlinson model that\ntakes into account the damped elastic deformation of the asperity. With its\ngreatly improved force sensitivity and very small sliding amplitude, our method\nenables rapid and detailed surface mapping of the full velocity-dependence of\nfrictional forces with less than 10~nm spatial resolution.",
        "positive": "Bias-free spin-wave phase shifter for magnonic logic: A design of a magnonic phase shifter operating without an external bias\nmagnetic field is proposed. The phase shifter uses a localized collective spin\nwave mode propagating along a domain wall \"waveguide\" in a dipolarly-coupled\nmagnetic dot array existing in a chessboard antiferromagnetic (CAFM) ground\nstate. It is demonstrated numerically that remagnetization of a single magnetic\ndot adjacent to the domain wall waveguide introduces a controllable phase shift\nin the propagating spin wave mode without significant change of the mode\namplitude. It is also demonstrated that a logic XOR gate can be realized in the\nsame system."
    },
    {
        "anchor": "Static friction scaling of physisorbed islands: the key is in the edge: The static friction preventing the free sliding of nanosized rare gas solid\nislands physisorbed on incommensurate crystalline surfaces is not completely\nunderstood. Simulations modeled on Kr/Pb(111) highlights the importance and the\nscaling behavior of the island's edge contribution to static friction.",
        "positive": "Orbital gyrotropic magneto-electric effect and its strain engineering in\n  monolayer Nb$X_2$: Electrical control of the orbital degrees of freedom is an important area of\nresearch in the emerging field of \"orbitronics.\" Orbital {\\it gyrotropic}\nmagneto-electric effect (OGME) is the generation of an orbital magnetization in\na nonmagnetic metal by an applied electric field. Here, we show that strain\ninduces a large GME in the monolayer Nb$X_2$ ($X =$ S, Se) normal to the plane,\nprimarily driven by the orbital moments of the Bloch bands as opposed to the\nconventional spin magnetization, without any need for spin-orbit coupling. The\nkey physics is captured within an effective two-band valley-orbital model and\nit is shown to be driven by three key ingredients: the intrinsic valley orbital\nmoment, broken $C_{3z}$ symmetry, and strain-induced Fermi surface changes. The\neffect can be furthermore switched by changing the strain condition, with\npotential for future device applications."
    },
    {
        "anchor": "Quantum Oscillations in the Chiral Magnetic Conductivity: In strong magnetic field the longitudinal magnetoconductivity in 3D chiral\nmaterials is shown to exhibit a new type of quantum oscillations arising from\nthe chiral magnetic effect (CME). These quantum CME oscillations are predicted\nto dominate over the Shubnikov-de Haas (SdH) ones in chiral materials with an\napproximately conserved chirality of quasiparticles at strong magnetic fields.\nThe phase of quantum CME oscillations differs from the phase of the\nconventional SdH oscillations by $\\pi/2$.",
        "positive": "Direct mechanical mixing in a nanoelectromechanical diode: We observe direct mechanical mixing in nanoelectromechanical transistors\nfabricated in semiconductor materials operating in the radio frequency band of\n10-1000 MHz. The device is made of a mechanically flexible pillar with a length\nof 240 nm and a diameter of 50 nm, placed between two electrodes in an\nimpedance matched coplanar wave guide. We find a non-linear IV-characteristic,\nwhich enables radio frequency mixing of two electromagnetic signals via the\nnanomechanical transistor. Potential applications for this mixer are\nultrasensitive displacement detection or signal processing in communication\nelectronic circuits requiring high-throughput insulation."
    },
    {
        "anchor": "Spin-orbit torques for current parallel and perpendicular to a domain\n  wall: We report field- and current-induced domain wall (DW) depinning experiments\nin Ta/Co20Fe60B20/MgO nanowires through a Hall cross geometry. While purely\nfield-induced depinning shows no angular dependence on in-plane fields, the\neffect of the current depends crucially on the internal DW structure, which we\nmanipulate by an external magnetic in-plane field. We show for the first time\ndepinning measurements for a current sent parallel to the DW and compare its\ndepinning efficiency with the conventional case of current flowing\nperpendicularly to the DW. We find that the maximum efficiency is similar for\nboth current directions within the error bars, which is in line with a\ndominating damping-like spin-orbit torque (SOT) and indicates that no large\nadditional torques arise for currents parallel to the DW. Finally, we find a\nvarying dependence of the maximum depinning efficiency angle for different DWs\nand pinning levels. This emphasizes the importance of our full angular scans\ncompared to previously used measurements for just two field directions\n(parallel and perpendicular to the DW) and shows the sensitivity of the\nspin-orbit torque to the precise DW structure and pinning sites.",
        "positive": "Electron-electron interaction effects in quantum point contacts: We consider interaction effects in quantum point contacts on the first\nquantization plateau, taking into account all non momentum-conserving\nprocesses. We compute low-temperature linear and non-linear conductance, shot\nnoise, and thermopower by perturbation theory, and show that they are\nconsistent with experimental observations on the so-called \"0.7 anomaly\". The\nfull temperature-dependent conductance is obtained from self-consistent\nsecond-order perturbation theory and approaches ~ e^2/h at higher temperatures,\nbut still smaller than the Fermi temperature."
    },
    {
        "anchor": "Magnetopolaronic effects in electron transport through a single-level\n  vibrating quantum dot: Magneto-polaronic effects are considered in electron transport through a\nsingle-level vibrating quantum dot subjected to a transverse (to the current\nflow) magnetic field. It is shown that the effects are most pronounced in the\nregime of sequential electron tunneling, where a polaronic blockade of the\ncurrent at low temperatures and an anomalous temperature dependence of the\nmagnetoconductance are predicted. In contrast, for resonant tunneling of\npolarons the peak conductance is not affected by the magnetic field.",
        "positive": "Quantized Anomalous Hall Effects in Skyrmion Crystal: We theoretically study the quantized anomalous Hall effect (QAHE) in skyrmion\ncrystal (SkX) without external magnetic field. The emergent magnetic field in\nSkX could be gigantic as much as $\\sim4000$T when its lattice constant is\n$\\sim1$nm. The band structure is not flat but has a finite gap in the low\nelectron-density regime. We also study the conditions to realize the QAHE for\nthe skyrmion size, carrier density, disorder strength and temperature.\nComparing the SkX and the system under the corresponding uniform magnetic\nfield, the former is more fragile against the temperature compared with the\nlatter since the gap is reduced by a factor of $\\sim$ 1/5, while they are\nalmost equally robust against the disorder. Therefore, it is expected that the\nQAHE of SkX system is realized even with strong disorder at room temperature\nwhen the electron density of the order of one per a skyrmion."
    },
    {
        "anchor": "Circuit Implementation of a Four-Dimensional Topological Insulator: The classification of topological insulators predicts the existence of\nhigh-dimensional topological phases that cannot occur in real materials, as\nthese are limited to three or fewer spatial dimensions. We use electric\ncircuits to experimentally implement a four-dimensional (4D) topological\nlattice. The lattice dimensionality is established by circuit connections, and\nnot by mapping to a lower-dimensional system. On the lattice's\nthree-dimensional surface, we observe topological surface states that are\nassociated with a nonzero second Chern number but vanishing first Chern\nnumbers. The 4D lattice belongs to symmetry class AI, which refers to\ntime-reversal-invariant and spinless systems with no special spatial symmetry.\nClass AI is topologically trivial in one to three spatial dimensions, so 4D is\nthe lowest possible dimension for achieving a topological insulator in this\nclass. This work paves the way to the use of electric circuits for exploring\nhigh-dimensional topological models.",
        "positive": "Fluctuations of spin transport through chaotic quantum dots with\n  spin-orbit coupling: As devices to control spin currents using the spin-orbit interaction are\nproposed and implemented, it is important to understand the fluctuations that\nspin-orbit coupling can impose on transmission through a quantum dot. Using\nrandom matrix theory, we estimate the typical scale of transmitted charge and\nspin currents when a spin current is injected into a chaotic quantum dot with\nstrong spin-orbit coupling. These results have implications for the functioning\nof the spin transistor proposed by Schliemann, Egues, and Loss. We use a\ndensity matrix formalism appropriate for treating arbitrary input currents and\nindicate its connections to the widely used spin-conductance picture. We\nfurther consider the case of currents entangled between two leads, finding\nlarger fluctuations."
    },
    {
        "anchor": "On Classical Fluctuations of Ballistic Conductance: Universal conductance fluctuations in disordered systems are one of the most\nknown quantum mesoscopic effects. For ballistic cavity with smooth confining\npotential however, one should observe a much larger classical sample-to-sample\nconductance fluctuations. It is shown, how bending of the phase space in case\nof chaotic dynamics leads to additional enhancement of such fluctuations.",
        "positive": "Probing spin dynamics and quantum relaxation in LiY0.998Ho0.002F4 via\n  19F NMR: We report measurements of 19F nuclear spin-lattice relaxation 1/T1 as a\nfunction of temperature and external magnetic field in LiY0.998Ho0.002F4 single\ncrystal, a single-ion magnet exhibiting interesting quantum effects. The 19F\n1/T1 is found to depend on the coupling with the diluted rare-earth (RE)\nmoments. Depending on the temperature range, a fast spin diffusion regime or a\ndiffusion limited regime is encountered. In both cases we find it possible to\nuse the 19F nucleus as a probe of the rare-earth spin dynamics. The results for\n1/T1 show a behavior similar to that observed in molecular nanomagnets, a\nresult which we attribute to the discreteness of the energy levels in both\ncases. At intermediate temperatures the lifetime broadening of the crystal\nfield split RE magnetic levels follows a T3 power law. At low temperature the\nfield dependence of 1/T1 shows peaks in correspondence to the critical magnetic\nfields for energy level crossings (LC). The results can be explained by\ninelastic scattering between the fluorine nuclear spins and the RE magnetic\nlevels. A key result of this study is that the broadening of the levels at LC\nis found to be become extremely small at low temperatures, about 1.7 mT, a\nvalue which is comparable to the weak dipolar fields at the RE lattice\npositions. Thus, unlike the molecular magnets, decoherence effects are strongly\nsuppressed, and it may be possible to measure directly the level repulsions at\navoided level crossings."
    },
    {
        "anchor": "Theory of inversion-$\\mathbb{Z}_{4}$ protected topological chiral hinge\n  states and its applications to layered antiferromagnets: We study positions of chiral hinge states in higher-order topological\ninsulators (HOTIs) with inversion symmetry. First, we exhaust all possible\nconfigurations of the hinge states in the HOTIs in all type-I magnetic space\ngroups with inversion symmetry by studying dependence of the sign of the\nsurface Dirac mass on surface orientations. In particular, in the presence of\nglide symmetry, for particular surface orientations, the surface Dirac mass\nchanges sign by changing the surface terminations. By applying this result to a\nlayered antiferromagnet (AFM), we find a difference in the hinge states between\nthe cases with an even and odd number of layers. In the case of an even number\nof layers, which does not preserve inversion symmetry, positions of hinge\nstates are not inversion symmetric. Nonetheless, these inversion-asymmetric\nhinge states result from the bulk topology. We show that their\ninversion-asymmetric configurations are uniquely determined from the symmetries\nand the topological invariant.",
        "positive": "Load-velocity-temperature relationship in frictional response of\n  microscopic contacts: Frictional properties of interfaces with dynamic chemical bonds have been the\nsubject of intensive experimental investigation and modeling, as it provides\nimportant insights into the molecular origin of the empirical rate and state\nlaws, which have been highly successful in describing friction from nano to\ngeophysical scales. Using previously developed theoretical approaches requires\ntime-consuming simulations that are impractical for many realistic tribological\nsystems. To solve this problem and set a framework for understanding\nmicroscopic mechanisms of friction at interfaces including multiple microscopic\ncontacts, we developed an analytical approach for description of friction\nmediated by dynamical formation and rupture of microscopic interfacial\ncontacts, which allows to calculate frictional properties on the time and\nlength scales that are relevant to tribological experimental conditions. The\nmodel accounts for the presence of various types of contacts at the frictional\ninterface and predicts novel dependencies of friction on sliding velocity,\ntemperature, and normal load, which are amenable to experimental observations.\nOur model predicts the velocity-temperature scaling, which relies on the\ninterplay between the effects of shear and temperature on the rupture of\ninterfacial contacts. The proposed scaling can be used to extrapolate the\nsimulation results to a range of very low sliding velocities used in nanoscale\nfriction experiments, which is still unreachable by simulations. For interfaces\nincluding two types of interfacial contacts with distinct properties, our model\npredicts novel double-peaked dependencies of friction on temperature and\nvelocity. Our work provides a promising avenue for the interpretation of the\nexperimental data on friction at interfaces including microscopic contacts and\nopens new pathways for the rational control of the frictional response."
    },
    {
        "anchor": "Quantum transport in graphene Hall bars: Effects of vacancy disorder: Using the tight-binding model, we investigate the influence of vacancy\ndisorder on electrical transport in graphene Hall bars in the presence of\nquantizing magnetic fields. Disorder, induced by a random distribution of\nmonovacancies, breaks the graphene sublattice symmetry and creates states\nlocalized on the vacancies. These states are observable in the bend resistance,\nas well as in the total DOS. Their energy is proportional to the square root of\nthe magnetic field, while their localization length is proportional to the\ncyclotron radius. At the energies of these localized states, the electron\ncurrent flows around the monovacancies and, as we show, it can follow\nunexpected paths depending on the particular arrangement of vacancies. We study\nhow these localized states change with the vacancy concentration, and what are\nthe effects of including the next nearest neighbor hopping term. Our results\nare also compared with the situation when double vacancies are present in the\nsystem. Double vacancies also induce localized states, but their energy and\nmagnetic field dependences are different. Their localization energy scales\nlinearly with the magnetic field, and their localization length appears not to\ndepend on the field strength.",
        "positive": "Hybrid Quantum Interferometer in Bifurcation Mode as a Latching Quantum\n  Readout: We have developed a new type of magnetometer consisting of a Hybrid Quantum\nInterference Device (HyQUID) that is set in a bi-stable state. We demonstrate\nits operation in a latching mode that can be employed to measure small changes\nin the applied flux. The device can be used to probe the flux state of a\nsuperconducting circuit using straightforward electrical resistance\nmeasurements, making it suitable as a simple qubit readout with low\nback-action."
    },
    {
        "anchor": "Hole spin relaxation in intrinsic and $p$-type bulk GaAs: We investigate hole spin relaxation in intrinsic and $p$-type bulk GaAs from\na fully microscopic kinetic spin Bloch equation approach. In contrast to the\nprevious study on hole spin dynamics, we explicitly include the intraband\ncoherence and the nonpolar hole-optical-phonon interaction, both of which are\ndemonstrated to be of great importance to the hole spin relaxation. The\nrelative contributions of the D'yakonov-Perel' and Elliott-Yafet mechanisms on\nhole spin relaxation are also analyzed. In our calculation, the screening\nconstant, playing an important role in the hole spin relaxation, is treated\nwith the random phase approximation. In intrinsic GaAs, our result shows good\nagreement with the experiment data at room temperature, where the hole spin\nrelaxation is demonstrated to be dominated by the Elliott-Yafet mechanism. We\nalso find that the hole spin relaxation strongly depends on the temperature and\npredict a valley in the density dependence of the hole spin relaxation time at\nlow temperature due to the hole-electron scattering. In $p$-type GaAs, we\npredict a peak in the spin relaxation time against the hole density at low\ntemperature, which originates from the distinct behaviors of the screening in\nthe degenerate and nondegenerate regimes. The competition between the screening\nand the momentum exchange during scattering events can also lead to a valley in\nthe density dependence of the hole spin relaxation time in the low density\nregime. At high temperature, the effect of the screening is suppressed due to\nthe small screening constant. Moreover, we predict a nonmonotonic dependence of\nthe hole spin relaxation time on temperature associated with the screening\ntogether with the hole-phonon scattering. Finally, we find that the\nD'yakonov-Perel' mechanism can markedly contribute to the .... (omitted due to\nthe limit of space)",
        "positive": "Dark-bright excitons mixing in alloyed InGaAs self-assembled quantum\n  dots: Quantum dots are arguably one of the best platforms for optically accessible\nspin based qubits. The paramount demand of extended qubit storage time can be\nmet by using quantum-dot-confined dark exciton: a longlived electron-hole pair\nwith parallel spins. Despite its name the dark exciton reveals weak\nluminescence that can be directly measured. The origins of this optical\nactivity remain largely unexplored. In this work, using the atomistic\ntight-binding method combined with configuration-interaction approach, we\ndemonstrate that atomic-scale randomness strongly affects oscillator strength\nof dark excitons confined in self-assembled cylindrical InGaAs quantum dots\nwith no need for faceting or shape-elongation. We show that this process is\nmediated by two mechanisms: mixing dark and bright configurations by exchange\ninteraction, and equally important appearance of non-vanishing optical\ntransition matrix elements that otherwise correspond to nominally forbidden\ntransitions in a non-alloyed case. The alloy randomness has essential impact on\nboth bright and dark exciton states, including their energy, emission\nintensity, and polarization angle. We conclude that, due to the atomic-scale\nalloy randomness, finding dots with desired dark exciton properties may require\nexploration of a large ensemble, similarly to how dots with low bright exciton\nsplitting are selected for entanglement generation."
    },
    {
        "anchor": "A strain-engineered graphene qubit in a nanobubble: We propose a controllable qubit in a graphene nanobubble with emergent\ntwo-level systems induced by pseudo-magnetic fields. We found that double\nquantum dots can be created by the strain-induced pseudo-magnetic fields of a\nnanobubble, and that their quantum states can be manipulated by either local\ngate potentials or the pseudo-magnetic fields. Graphene qubits clearly exhibit\nan avoided crossing behavior via electrical detuning, with energy splittings of\nabout a few meV. We also show a remarkable tunability of our device design that\nallows for the fine control of the Landau--Zener transition probability through\nstrain engineering of the nanobubble, showing half-and-half splitting at the\navoided crossing point. Further, we demonstrate that the two-level systems in\nthe nanobubble exhibit Rabi oscillations near the avoided crossing point,\nresulting in very fast Rabi cycles of a few ps.",
        "positive": "Magnon Spin Photogalvanic Effect in Collinear Ferromagnets: We propose a spin photogalvanic effect of magnons with broken inversion\nsymmetry. The dc spin photocurrent is generated via the Aharonov-Casher effect,\nwhich includes the Drude, Berry curvature dipole, shift, injection, and\nrectification components with distinct quantum geometric origin. Based on a\nsymmetry classification, we uncover that there exist linearly polarized (LP)\nmagnon spin photocurrent responses in the breathing kagome-lattice ferromagnet\nwith Dzyaloshinskii-Moriya interaction, and the circularly polarized (CP)\nresponses due to the symmetry breaking by applying a uniaxial strain. We\naddress that the topological phase transitions can be characterized by the spin\nphotocurrents. This study presents a deeper insight into the nonlinear\nresponses of light-magnon interactions, and suggests a possible way to generate\nand control the magnon spin current in real materials."
    },
    {
        "anchor": "Quantum Hall effect induced by chiral Landau levels in topological\n  semimetal films: Motivated by recent transport experiments, we theoretically study the quantum\nHall effect in topological semimetal films. Owing to the confinement effect,\nthe bulk subbands originating from the chiral Landau levels establish energy\ngaps that have quantized Hall conductance and can be observed in relatively\nthick films. We find that the quantum Hall state is strongly anisotropic for\ndifferent confinement directions not only due to the presence of the surface\nstates but also because of the bulk chiral Landau levels. As a result, we\nre-examine the quantum Hall effect from the surface Fermi arcs and chiral modes\nin Weyl semimetals and give a more general view into this problem. Besides, we\nalso find that when a topological Dirac semimetal is confined in its rotational\nsymmetry axis, it hosts both quantum Hall and quantum spin Hall states, in\nwhich the helical edge states are protected by the conservation of the spin-$z$\ncomponent.",
        "positive": "Hydrodynamic theory of coupled current and magnetization dynamics in\n  spin-textured antiferromagnets: Antiferromagnets with vanishingly small (or zero) magnetization are\ninteresting candidates for spintronics applications. In the present paper we\npropose two models for description of the current-induced phenomena in\nantiferromagnetic textures. We show that the magnetization that originates from\nrotation or oscillations of antiferromagnetic vector can, via $sd$-exchange\ncoupling, polarize the current and give rise to adiabatic and nonadiabatic spin\ntorques. Due to the Lorentz-type dynamics of antiferromagnetic moments (unlike\nthe Galilenian-like dynamics in ferromagnets), the adiabatic spin torque\naffects the characteristic lengthscale of the moving texture. Nonadiabatic spin\ntorque contributes to the energy pumping and can induce the stable motion of\nantiferromagnetic texture, but, in contrast to ferromagnets, has pure dynamic\norigin. We also consider the current-induced phenomena in artificial\nantiferromagnets where the current maps the staggered magnetization of the\nstructure. In this case the effect of nonadiabatic spin torque is similar to\nthat in ferromagnetic constituents of the structure. In particular, the current\ncan remove degeneracy of the translational antiferromagnetic domains\nindistinguishable in the external magnetic field and thus can set into motion\nthe 180$^\\circ$ domain wall."
    },
    {
        "anchor": "Intrinsic Spin Hall Effect with Spin-Tensor-Momentum Coupling: We derive the spin continuity equation by using the Noether's theorem. A new\ntype of spin-tensor Hall current is found in the continuity equation. The\nspin-tensor Hall current is originating from the coupling of the spin-tensor\nand the momentum. The intrinsic spin Hall effect in the two-dimensional fermion\nmodel with the spin-orbit coupling and spin-tensor-momentum coupling is\nstudied. The total spin Hall conductivity with the presence of the spin-tensor\nHall current is calculated. The numerical results indicate that the total spin\nHall conductivity is enhanced by the contribution of the spin-tensor-momentum\ncoupling. The spin-tensor-momentum coupling may increase the spin transport in\nthe intrinsic spin Hall effect.",
        "positive": "Graphene kirigami as a platform for stretchable and tunable quantum dot\n  arrays: The quantum transport properties of a graphene kirigami similar to those\nstudied in recent experiments are calculated in the regime of elastic,\nreversible deformations. Our results show that, at low electronic densities,\nthe conductance profile of such structures replicates that of a system of\ncoupled quantum dots, characterized by a sequence of minibands and stop-gaps.\nThe conductance and I-V curves have different characteristics in the distinct\nstages of elastic deformation that characterize the elongation of these\nstructures. Notably, the effective coupling between localized states is\nstrongly reduced in the small elongation stage, whereas in the large elongation\nregime the development of strong, localized pseudomagnetic field barriers can\nreinforce the coupling and reestablish resonant tunneling across the kirigami.\nThis provides an interesting example of interplay between geometry and\npseudomagnetic field-induced confinement. The alternating miniband and\nstop-gaps in the transmission lead to I-V characteristics with negative\ndifferential conductance in well defined energy/doping ranges. These effects\nshould be stable in a realistic scenario that includes edge roughness and\nCoulomb interactions, as these are expected to further promote localization of\nstates at low energies in narrow segments of graphene nanostructures."
    },
    {
        "anchor": "Landau-Zener transitions in qubits controlled by electromagnetic fields: We investigate the influence of a dipole interaction with a classical\nradiation field on a qubit during a continuous change of a control parameter.\nIn particular, we explore the non-adiabatic transitions that occur when the\nqubit is swept with linear speed through resonances with the time-dependent\ninteraction. Two classical problems come together in this model: the\nLandau-Zener and the Rabi problem. The probability of Landau-Zener transitions\nnow depends sensitively on the amplitude, the frequency and the phase of the\nRabi interaction. The influence of the static phase turns out to be\nparticularly strong, since this parameter controls the time-reversal symmetry\nof the Hamiltonian. In the limits of large and small frequencies, analytical\nresults obtained within a rotating-wave approximation compare favourably with a\nnumerically exact solution. Some physical realizations of the model are\ndiscussed, both in microwave optics and in magnetic systems.",
        "positive": "Voltage probe model of spin decay in a chaotic quantum dot, with\n  applications to spin-flip noise and entanglement production: The voltage probe model is a model of incoherent scattering in quantum\ntransport. Here we use this model to study the effect of spin-flip scattering\non electrical conduction through a quantum dot with chaotic dynamics. The spin\ndecay rate gamma is quantified by the correlation of spin-up and spin-down\ncurrent fluctuations (spin-flip noise). The resulting decoherence reduces the\nability of the quantum dot to produce spin-entangled electron-hole pairs. For\ngamma greater than a critical value gamma_c, the entanglement production rate\nvanishes identically. The statistical distribution P(gamma_c) of the critical\ndecay rate in an ensemble of chaotic quantum dots is calculated using the\nmethods of random-matrix theory. For small gamma_c this distribution is\nproportional to gamma_c^(-1+beta/2), depending on the presence (beta=1) or\nabsence (beta=2) of time-reversal symmetry. To make contact with experimental\nobservables, we derive a one-to-one relationship between the entanglement\nproduction rate and the spin-resolved shot noise, under the assumption that the\ndensity matrix is isotropic in the spin degrees of freedom. Unlike the Bell\ninequality, this relationship holds for both pure and mixed states. In the\ntunneling regime, the electron-hole pairs are entangled if and only if the\ncorrelator of parallel spin currents is at least twice larger than the\ncorrelator of antiparallel spin currents."
    },
    {
        "anchor": "Multiple gaps in the tight-binding band of a pentagonal lattice: Multiple gaps in the tight-binding band of a pentagonal lattice are found.\nUnlike the Cairo pentagonal lattice this lattice is made of irregular pentagons\nwith arms of different lengths. The tight-binding Hamiltonian is exactly solved\nto obtain analytic expressions of dispersion relations and eigenvectors. Four\ndifferent band-gaps are identified along with two distinct indirect band-gaps\nat the Harrison point. Multiple band-gaps in this model may give rise to exotic\nelectronic properties.",
        "positive": "Trapped fermionic clouds distorted from the trap shape due to many-body\n  effects: We present a general approach for calculating densities and other local\nquantities of trapped Fermi gases, when the cloud shape is distorted with\nrespect to the trap shape due to global energy considerations. Our approach\nprovides a consistent way to explore physics beyond the local density\napproximation, if this is necessary due to the distortion. We illustrate this\nby analyzing in detail experimentally observed distortions in an imbalanced\nFermi mixture in an elongated trap. In particular, we demonstrate in that case\ndramatic deviations from ellipsoidal cloud shapes arising from the competition\nbetween surface and bulk energies."
    },
    {
        "anchor": "Transport properties of spin superfluids: comparing easy-plane ferro-\n  and antiferromagnets: We present a study on spin-superfluid transport based on an atomistic,\nclassical spin model. Easy-plane ferro- as well as antiferromagnets are\nconsidered, which allows for a direct comparison of these two material classes\nbased on the same model assumptions. We find a spin-superfluid transport which\nis robust against variations of the boundary conditions, thermal fluctuations,\nand dissipation modeled via Gilbert damping. Though the spin accumulations is\nsmaller for antiferromagnets the range of the spin-superfluid transport turns\nout to be identical for ferro- and antiferromagnets. Finally, we calculate and\nexplore the role of the driving frequency and especially the critical\nfrequency, where phase slips occur and the spin accumulation breaks down.",
        "positive": "Full counting statistics of energy fluctuations in a driven quantum\n  resonator: We consider the statistics of time-integrated energy fluctuations of a driven\nbosonic resonator (as measured by a QND detector), using the standard Keldysh\nprescription to define higher moments. We find that due to an effective\ncascading of fluctuations, these statistics are surprisingly non-classical: the\nlow-temperature, quantum probability distribution is not equivalent to the\nhigh-temperature classical distribution evaluated at some effective\ntemperature. Moreover, for a sufficiently large drive detuning and low\ntemperatures, the Keldysh-ordered quasi-probability distribution characterizing\nthese fluctuations fails to be positive-definite; this is similar to the full\ncounting statistics of charge in superconducting systems. We argue that this\nindicates a kind of non-classical behaviour akin to that tested by Leggett-Garg\ninequalities."
    },
    {
        "anchor": "Photoluminescence imaging of single photon emitters within nanoscale\n  strain profiles in monolayer WSe$_2$: Local deformation of atomically thin van der Waals materials provides a\npowerful approach to create site-controlled chip-compatible single-photon\nemitters (SPEs). However, the microscopic mechanisms underlying the formation\nof such strain-induced SPEs are still not fully clear, which hinders further\nefforts in their deterministic integration with nanophotonic structures for\ndeveloping practical on-chip sources of quantum light. Here we investigate SPEs\nwith single-photon purity up to 98% created in monolayer WSe$_2$ via\nnanoindentation. Using photoluminescence imaging in combination with atomic\nforce microscopy, we locate single-photon emitting sites on a deep\nsub-wavelength spatial scale and reconstruct the details of the surrounding\nlocal strain potential. The obtained results suggest that the origin of the\nobserved single-photon emission is likely related to strain-induced spectral\nshift of dark excitonic states and their hybridization with localized states of\nindividual defects.",
        "positive": "Quantum trajectory equation for multiple qubits in circuit QED:\n  Generating entanglement by measurement: In this paper we derive an effective master equation and quantum trajectory\nequation for multiple qubits in a single resonator and in the large resonator\ndecay limit. We show that homodyne measurement of the resonator transmission is\na weak measurement of the collective qubit inversion. As an example of this\nresult, we focus on the case of two qubits and show how this measurement can be\nused to generate an entangled state from an initially separable state. This is\nrealized without relying on an entangling Hamiltonian. We show that, for {\\em\ncurrent} experimental values of both the decoherence and measurement rates,\nthis approach can be used to generate highly entangled states. This scheme\ntakes advantage of the fact that one of the Bell states is decoherence-free\nunder Purcell decay."
    },
    {
        "anchor": "Damping-Enhanced Magnon Transmission: The inevitable Gilbert damping in magnetization dynamics is usually regarded\nas detrimental to spin transport. Here we demonstrate in a\nferromagnetic-insulator--normal-metal heterostructure that the strong momentum\ndependence and chirality of the eddy-current-induced damping causes also\nbeneficial scattering properties. Here we show that a potential barrier that\nreflects magnon wave packets becomes transparent in the presence of a metallic\ncap layer, but only in one direction. We formulate the unidirectional\ntransmission in terms of a generalized group velocity with an imaginary\ncomponent and the magnon skin effect. This trick to turn presumably harmful\ndissipation into useful functionalities should be useful for future quantum\nmagnonic devices.",
        "positive": "Real-time milli-Kelvin thermometry in a semiconductor qubit architecture: We report local time-resolved thermometry in a silicon nanowire quantum dot\ndevice designed to host a linear array of spin qubits. Using two alternative\nmeasurement schemes based on rf reflectometry, we are able to probe either\nlocal electron or phonon temperatures with $\\mu$s-scale time resolution and a\nnoise equivalent temperature of $3$ $\\rm mK/\\sqrt{\\rm Hz}$. Following the\napplication of short microwave pulses, causing local periodic heating,\ntime-dependent thermometry can track the dynamics of thermal excitation and\nrelaxation, revealing clearly different characteristic time scales. This work\nopens important prospects to investigate the out-of-equilibrium thermal\nproperties of semiconductor quantum electronic devices operating at very low\ntemperature. In particular, it may provide a powerful handle to understand\nheating effects recently observed in semiconductor spin-qubit systems."
    },
    {
        "anchor": "Kinetic theory of Coulomb drag in two monolayers of graphene: from the\n  Dirac point to the Fermi liquid regime: We theoretically investigate Coulomb drag in a system of two parallel\nmonolayers of graphene. Using a Boltzmann equation approach we study a variety\nof limits ranging from the non-degenerate interaction dominated limit close to\ncharge neutrality all the way to the Fermi liquid regime. In the non-degenerate\nlimit we find that the presence of the passive layer can largely influence the\nconductivity of the active layer despite the absence of drag. This induces a\nnon-trivial temperature behavior of the single layer conductivity and\nfurthermore suggests a promising strategy towards increasing the role of\ninelastic scattering in future experiments. For small but finite chemical\npotential we find that the drag resistivity varies substantially as a function\nof the ratio of inelastic and elastic scattering. We find that an extrapolation\nfrom finite chemical potential to zero chemical potential and to the clean\nsystem is delicate and the order of limits matters. In the Fermi liquid regime\nwe analyze drag as a function of temperature $T$ and the distance $d$ between\nthe layers and compare our results to existing theoretical and experimental\nresults. In addition to the conventional $1/d^4$-dependence with an associated\n$T^2$-behavior we find there is another regime of $1/d^5$-dependence where drag\nvaries in linear-in-$T$ fashion. The relevant parameter separating these two\nregimes is given by $\\bar{d}=T d/v_F$ ($v_F$ is the Fermi velocity), where\n$\\bar{d} \\ll1$ corresponds to $T^2$-behavior, while $\\bar{d}\\gg1$ corresponds\nto $T$-behavior.",
        "positive": "Conductivity of a generic helical liquid: A quantum spin Hall insulator is a two-dimensional state of matter consisting\nof an insulating bulk and one-dimensional helical edge states. While these edge\nstates are topologically protected against elastic backscattering in the\npresence of disorder, interaction-induced inelastic terms may yield a finite\nconductivity. By using a kinetic equation approach, we find the backscattering\nrate $\\tau^{-1}$ and the semiclassical conductivity in the regimes of high\n($\\omega \\gg \\tau^{-1}$) and low ($\\omega \\ll \\tau^{-1}$) frequency. By\ncomparing the two limits, we find that the parametric dependence of\nconductivity is described by the Drude formula for the case of a disordered\nedge. On the other hand, in the clean case where the resistance originates from\numklapp interactions, the conductivity takes a non-Drude form with a parametric\nsuppression of scattering in the dc limit as compared to the ac case. This\nbehavior is due to the peculiarity of umklapp scattering processes involving\nnecessarily the state at the \"Dirac point\". In order to take into account\nLuttinger liquid effects, we complement the kinetic equation analysis by\ntreating interactions exactly in bosonization and calculating conductivity\nusing the Kubo formula. In this way, we obtain the frequency and temperature\ndependence of conductivity over a wide range of parameters. We find the\ntemperature and frequency dependence of the transport scattering time in a\ndisordered system as $\\tau \\sim [\\max{(\\omega,T)}]^{-2K-2}$, for $K>2/3$ and\n$\\tau \\sim [\\max{(\\omega,T)}]^{-8K+2}$ for $K <2/3$."
    },
    {
        "anchor": "Selective probing of photo-induced charge and spin dynamics in the bulk\n  and surface of a topological insulator: Topological insulators possess completely different spin-orbit coupled bulk\nand surface electronic spectra that are each predicted to exhibit exotic\nresponses to light. Here we report time-resolved fundamental and second\nharmonic optical pump-probe measurements on the topological insulator Bi2Se3 to\nindependently measure its photo-induced charge and spin dynamics with bulk and\nsurface selectivity. Our results show that a transient net spin density can be\noptically induced in both the bulk and surface, which may drive spin transport\nin topological insulators. By utilizing a novel rotational anisotropy analysis\nwe are able to separately resolve the spin de-polarization, intraband cooling\nand interband recombination processes following photo-excitation, which reveal\nthat spin and charge degrees of freedom relax on very different time scales\nowing to strong spin-orbit coupling.",
        "positive": "Many-Body Coherence in Quantum Transport: In this study, we propose the concept of harnessing quantum coherence to\ncontrol electron transport in a many-body system. Combining an open quantum\nsystem technique based on Hubbard operators, we show that many-body coherence\ncan eliminate the well-known Coulomb staircase and cause strong negative\ndifferential resistance. To explore the mechanism, we analytically derive the\ncurrent-coherence relationship in the zero electron-phonon coupling limit.\nFurthermore, by incorporating a gate field, we demonstrate the possibility of\nconstructing a coherence-controlled transistor. This development opens up a new\ndirection for exploring quantum electronic devices based on many-body\ncoherence."
    },
    {
        "anchor": "Microscopic model of the doping dependence of line widths in monolayer\n  transition metal dichalcogenides: A fully microscopic model of the doping-dependent exciton and trion line\nwidths in the absorption spectra of monolayer transition metal dichalcogenides\nin the low temperature and low doping regime is explored. The approach is based\non perturbation theory and avoids the use of phenomenological parameters. In\nthe low-doping regime, we find that the trion line width is relatively\ninsensitive to doping levels while the exciton line width increases\nmonotonically with doping. On the other hand, we argue that the trion line\nwidth shows a somewhat stronger temperature dependence. The magnitudes of the\nline widths are likely to be masked by phonon scattering for $T \\geq 20$ K in\nencapsulated samples in the low doping regime. We discuss the breakdown of\nperturbation theory, which should occur at relatively low doping levels and low\ntemperatures. Our work also paves the way towards understanding a variety of\nrelated scattering processes, including impact ionization and Auger scattering\nin clean 2D samples.",
        "positive": "Unified role of Green's function poles and zeros in topological\n  insulators: Green's function zeros, which can emerge only if correlation is strong, have\nbeen for long overlooked and believed to be devoid of any physical meaning,\nunlike Green's function poles. Here, we prove that Green's function zeros\ninstead contribute on the same footing as poles to determine the topological\ncharacter of an insulator. The key to the proof, worked out explicitly in 2D\nbut easily extendable in 3D, is to express the topological invariant in terms\nof a quasiparticle thermal Green's function matrix $G_*(i\\epsilon,\\mathbf{k})=\n1/\\big(i\\epsilon-H_*(\\epsilon,\\mathbf{k})\\big)$, with hermitian\n$H_*(\\epsilon,\\mathbf{k})$, by filtering out the positive definite\nquasiparticle residue. In that way, the topological invariant is easily found\nto reduce to the TKNN formula for quasiparticles described by the\nnon-interacting Hamiltonian $H_*(0,\\mathbf{k})$. Since the poles of the\nquasiparticle Green's function $G_*(\\epsilon,\\mathbf{k})$ on the real frequency\naxis correspond to poles and zeros of the physical-particle Green's function\n$G(\\epsilon,\\mathbf{k})$, both of them equally determine the topological\ncharacter of an insulator."
    },
    {
        "anchor": "Number of equidistant neighbors on honeycomb lattice: A convenient scheme is presented for calculating potential energy of van der\nWaals interacting bilayer graphene and other similar 2D compounds. It is based\non the notion of the existence of two types of local symmetry of carbon atoms\nordering, a 3- and 6-fold one. Potential energy of an atom is expressed as a\nsum of contributions from rings of equidistant atoms on neighboring layer.\nMethods are described to compute the radius of rings of equidistant atoms and\nnumber of atoms they contain. Exact positions of atoms are found as well,\nallowing to apply the introduced method in modelling of anisotropic potentials\nand to be used when twisting between layers is present.",
        "positive": "Physisorption of DNA nucleobases on h-BN and graphene: vdW-corrected DFT\n  calculations: We present a comparative study of DNA nucleobases [guanine (G), adenine (A),\nthymine (T), and cytosine (C)] adsorbed on hexagonal boron nitride\n(\\textit{h}-BN) sheet and graphene, using local, semilocal, and van der Waals\n(vdW) energy-corrected density-functional theory (DFT) calculations.\nIntriguingly, despite the very different electronic properties of BN sheet and\ngraphene, we find rather similar binding energies for the various nucleobase\nmolecules when adsorbed on the two types of sheets. The calculated binding\nenergies of the four nucleobases using the local, semilocal, and DFT+vdW\nschemes are in the range of 0.54 ${\\sim}$ 0.75 eV, 0.06 ${\\sim}$ 0.15 eV, and\n0.93 ${\\sim}$ 1.18 eV, respectively. In particular, the DFT+vdW scheme predicts\nnot only a binding energy predominantly determined by vdW interactions between\nthe base molecules and their substrates decreasing in the order of\nG$>$A$>$T$>$C, but also a very weak hybridization between the molecular levels\nof the nucleobases and the ${\\pi}$-states of the BN sheet or graphene. This\nphysisorption of G, A, T, and C on the BN sheet (graphene) induces a small\ninterfacial dipole, giving rise to an energy shift in the work function by 0.11\n(0.22), 0.09 (0.15), $-$0.05 (0.01), and 0.06 (0.13) eV, respectively."
    },
    {
        "anchor": "Exact master equation and decoherence dynamics of Majorana zero modes\n  under the gate-induced charge fluctuation: In this paper, we derive the exact master equation to investigate the\ndecoherence dynamics of Majorana zero modes in the Kitaev model, a 1D\n$p\\,$-wave spinless topological superconducting chain (TSC), that is disturbed\nby charge fluctuations through gate controls. The exact master equation is\nderived by extending Feynman-Vernon influence functional approach to fermionic\nopen systems involving pairing excitations. We obtain the exact master\nequations for the zero-energy bogoliubon in the TSC, and then transfer it into\nthe master equation for Majorana zero modes. Within this exact master equation\nformalism, we can describe in detail the non-Markovian decoherence dynamics of\nzero-energy bogolibons as well as the Majorana zero modes under local\nperturbations. We find that at zero temperature, there is a zero-energy\nlocalized bound state which is not the original zero-energy bogoliubon or the\noriginal Majorana zero mode but a localized bound state of Majorana zero mode\nafter the charge fluctuation is taken into account. It is this zero-energy\nlocalized bound state that protects Majorana zero modes from decoherence, as a\nlong-time non-Markovain memory effect. However, for the environment at finite\ntemperature, the zero-energy localized bound state cannot be formed when\nMajorana zero modes are locally perturbed, and decoherence is inevitable.",
        "positive": "New topological invariants in non-Hermitian systems: Both theoretical and experimental studies of topological phases in\nnon-Hermitian systems have made a remarkable progress in the last few years of\nresearch. In this article, we review the key concepts pertaining to topological\nphases in non-Hermitian Hamiltonians with relevant examples and realistic model\nsetups. Discussions are devoted to both the adaptations of topological\ninvariants from Hermitian to non-Hermitian systems, as well as origins of new\ntopological invariants in the latter setup. Unique properties such as\nexceptional points and complex energy landscapes lead to new topological\ninvariants including winding number/vorticity defined solely in the complex\nenergy plane, and half-integer winding/Chern numbers. New forms of Kramers\ndegeneracy appear here rendering distinct topological invariants. Modifications\nof adiabatic theory, time-evolution operator, biorthogonal bulk-boundary\ncorrespondence lead to unique features such as topological displacement of\nparticles, `skin-effect', and edge-selective attenuated and amplified\ntopological polarizations without chiral symmetry. Extension and realization of\ntopological ideas in photonic systems are mentioned. We conclude with\ndiscussions on relevant future directions, and highlight potential applications\nof some of these unique topological features of the non-Hermitian Hamiltonians."
    },
    {
        "anchor": "Graphyne on metallic surfaces: an improved graphene: We showed how a structural modification of graphene, which gives a carbon\nallotrope graphyne, can induce an energy gap at the K point of the Brillouin\nzone. Upon adsorption on metallic surfaces, the same mechanism is responsible\nfor the further modification of the energy gap which occurs via the charge\ntransfer mechanism. We performed the calculation based on the density\nfunctional theory with the novel non-local vdW-DF correlation of the adsorption\nof graphyne on Cu(111), Ni(111) and Co(0001) surfaces and showed the dependence\nof the gap change on the charge transfer in the system. The binding of graphyne\nappears to be stronger than of graphene on the same surfaces.",
        "positive": "Negative Domain Wall Contribution to the Resistivity of Microfabricated\n  Fe Wires: The effect of domain walls on electron transport has been investigated in\nmicrofabricated Fe wires (0.65 to 20 $\\mu m$ linewidths) with controlled stripe\ndomains. Magnetoresistance (MR) measurements as a function of domain wall\ndensity, temperature and the angle of the applied field are used to determine\nthe low field MR contributions due to conventional sources in ferromagnetic\nmaterials and that due to the erasure of domain walls. A negative domain wall\ncontribution to the resistivity is found. This result is discussed in light of\na recent theoretical study of the effect of domain walls on quantum transport."
    },
    {
        "anchor": "Layer photovoltaic effect in van der Waals heterostructures: We argue that the layer electric polarization of noncentrosymmetric layered\nheterostructures can be generically controlled by light yielding a layer\nphotovoltaic effect (LPE). The LPE possesses a rich phenomenology and can arise\nfrom myriad distinct mechanisms displaying strong sensitivity to symmetry\n(e.g., point group and time-reversal) as well as the presence/absence of a\nFermi surface. We systematically classify these and unveil how LPE manifests\nfor a range of light polarizations and even for unpolarized light. These\nunusual layer photoresponses can be realized in a range of layered\nheterostructures such as bilayer graphene aligned on hexagonal Boron Nitride\nand manifest sizeable layer polarization susceptibilities in the terahertz\nfrequency range that can be used as novel means of bulk photodetection.",
        "positive": "Nonlinear thermoelectric transport in single-molecule junctions: the\n  effect of electron-phonon interactions: In the present work, we theoretically analyze the steady-state thermoelectric\ntransport through a single-molecule junction with a vibrating bridge. Thermally\ninduced charge current in the system is explored using a nonequilibrium Green's\nfunctions formalism. We study combined effects of Coulomb interactions between\ncharge carriers on the bridge and electron-phonon interactions on the\nthermocurrent beyond the linear response regime. It is shown that\nelectron-vibron interactions may significantly affect both magnitude and\ndirection of the thermocurrent, and vibrational signatures may appear."
    },
    {
        "anchor": "Quantum spill out in few-nanometer metal gaps: Effect on gap plasmons\n  and reflectance from ultrasharp groove arrays: Plasmons in ultranarrow metal gaps are highly sensitive to the electron\ndensity profile at the metal surfaces. Using a fully quantum mechanical\napproach, we study the effects of electron spill-out on gap plasmons and\nreflectance from ultrasharp metal grooves. We demonstrate that the mode index\nof ultranarrow gap plasmons converges to the bulk refractive index in the limit\nof vanishing gap and, thereby, rectify the unphysical divergence found in\nclassical models. Surprisingly, spill-out also significantly increases the\nplasmonic absorption for few-nanometer gaps and lowers the reflectance from\narrays of ultrasharp metal grooves. These findings are explained in terms of\nenhanced gap plasmon absorption taking place inside the gap 1-2 {\\AA} from the\nwalls and delocalization near the groove bottom. Reflectance calculations\ntaking spill-out into account are shown to be in much better agreement with\nmeasurements compared with classical models.",
        "positive": "Photon-assisted resonant Andreev reflections: Yu-Shiba-Rusinov and\n  Majorana states: Photon-assisted tunneling frequently provides detailed information on the\nunderlying charge-transfer process. In particular, the Tien-Gordon approach and\nits extensions predict that the sideband spacing in bias voltage is a direct\nfingerprint of the number of electrons transferred in a single tunneling event.\nHere, we analyze photon-assisted tunneling into subgap states in\nsuperconductors in the limit of small temperatures and bias voltages where\ntunneling is dominated by resonant Andreev processes and does not conform to\nthe predictions of simple Tien-Gordon theory. Our analysis is based on a\nsystematic Keldysh calculation of the subgap conductance and provides a\ndetailed analytical understanding of photon-assisted tunneling into subgap\nstates, in excellent agreement with a recent experiment. We focus on tunneling\nfrom superconducting electrodes and into Yu-Shiba-Rusinov states associated\nwith magnetic impurities or adatoms, but we also explicitly extend our results\nto include normal-metal electrodes or other types of subgap states in\nsuperconductors. In particular, we argue that photon-assisted Andreev\nreflections provide a high-accuracy method to measure small, but nonzero\nenergies of subgap states which can be important for distinguishing\nconventional subgap states from Majorana bound states."
    },
    {
        "anchor": "A compact heat transfer model based on an enhanced Fourier law for\n  analysis of frequency-domain thermoreflectance experiments: A recently developed enhanced Fourier law is applied to the problem of\nextracting thermal properties of materials from frequency-domain\nthermoreflectance (FDTR) experiments. The heat transfer model comprises\ncontributions from two phonon channels; one a high-heat-capacity diffuse\nchannel consisting of phonons of mean free path (MFP) less than a threshold\nvalue, and the other a low-heat-capacity channel consisting of phonons with MFP\nhigher than this value that travel quasi-ballistically over length scales of\ninterest. The diffuse channel is treated using the Fourier law, while the\nquasi-ballistic channel is analyzed using a second-order spherical harmonic\nexpansion of the phonon distribution function. A recent analysis of FDTR\nexperimental data suggested the use of FDTR in deriving large portions of the\nMFP accumulation function; however, it is shown here that the data can\nadequately be explained using our minimum-parameter model, thus highlighting an\nimportant limitation of FDTR experiments in exploring the accumulation function\nof bulk matter.",
        "positive": "Density functional study of the magnetic properties of $Bi_{4}Mn$\n  clusters: Discrepancy between theory and experiment: We have performed collinear and non collinear calculations on neutral Bi4Mn,\nand collinear ones on ionized Bi4Mn with charges +1 and -1 to find out why\ntheoretical calculations will not predict the magnetic state found in the\nexperiment. We have used the density functional theory to find a fit between\nthe theoretical prediction of the magnetic moment with the experimental value.\nOur calculations have consisted in a structure search of local energy minima,\nand then a search of the magnetic lowest energy state for each resulting\nisomer. The geometry optimization found 3 local minima whose fundamental state\nis the doublet spin state, which could not be found in previous theoretical\nworks, but they are higher in energy than the lowest-lying isomer by\napproximately 1.75 eV. This magnetic state could help understand the\nexperiment. Calculations of non-collinear magnetic states for the Bi4Mn do not\nlower the total magnetic moment. We conclude arguing how the 3 isomers with\ndoublet state could actually be the ones measured in the experiment."
    },
    {
        "anchor": "Hermitian zero modes protected by nonnormality: Application of\n  pseudospectra: Recently, it was established that there exists a direct relation between the\nnon-Hermitian skin effects, -strong dependence of spectra on boundary\nconditions for non-Hermitian Hamiltonians-, and boundary zero modes for\nHermitian topological insulators. On the other hand, in terms of the spectral\ntheory, the skin effects can also be interpreted as instability of spectra for\nnonnormal (non-Hermitian) Hamiltonians. Applying the latter interpretation to\nthe former relation, we develop a theory of zero modes with quantum anomaly for\ngeneral Hermitian lattice systems. Our theory is applicable to a wide range of\nsystems: Majorana chains, non-periodic lattices, and long-range hopping\nsystems. We relate exact zero modes and quasi-zero modes of a Hermitian system\nto spectra and pseudospectra of a non-Hermitian system, respectively. These\nzero and quasi-zero modes of a Hermitian system are robust against a class of\nperturbations even if there is no topological protection. The robustness is\nmeasured by nonnormality of the corresponding non-Hermitian system. We also\npresent explicit construction of such zero modes by using a graphical\nrepresentation of lattice systems. Our theory reveals the presence of\nnonnormality-protected zero modes, as well as the usefulness of the\nnonnormality and pseudospectra as tools for topological and/or non-Hermitian\nphysics.",
        "positive": "Identification of dark axisymmetric plasma modes in partially gated\n  two-dimensional electron gas disk: We investigate the dark axisymmetric plasmon spectrum for partially gated\ntwo-dimensional gas of the disk shape. The extension of the central gate spot\nprovides a change in plasmon dispersion from the root to a linear dependence on\nthe wave vector. Intriguingly, the interaction between neighboring modes occurs\nbecause of stepwise change in carrier screening across the circumference of the\ngate. This behavior is unexpected when changing from a fully screened to\nunscreened two-dimensional gas by increasing the dielectric width under the\ngate [A.L.Fetter, Phys.Rev.B 33, 5221 (1986)]. Our results provide the accurate\nidentification of axisymmetric plasmon modes recently observed in experiment\nand, in addition, pave the way for feedback plasmon resonator study."
    },
    {
        "anchor": "Time-dependent transport in open systems based on quantum master\n  equations: Electrons in the active region of a nanostructure constitute an open\nmany-body quantum system, interacting with contacts, phonons, and photons. We\nreview the basic premises of the open system theory, focusing on the common\napproximations that lead to Markovian and non-Markovian master equations for\nthe reduced statistical operator. We highlight recent progress on the use of\nmaster equations in quantum transport, and discuss the limitations and\npotential new directions of this approach.",
        "positive": "Theory of Magnetic Edge States in Chiral Graphene Nanoribbons: Using a model Hamiltonian approach including electron-electron interactions,\nwe systematically investigate the electronic structure and magnetic properties\nof chiral graphene nanoribbons. We show that the presence of magnetic edge\nstates is an intrinsic feature of smooth graphene nanoribbons with chiral\nedges, and discover a number of structure-property relations. Specifically, we\nstudy the dependence of magnetic moments and edge-state energy splittings on\nthe nanoribbon width and chiral angle as well as the role of environmental\nscreening effects. Our results address a recent experimental observation of\nsignatures of magnetic ordering in chiral graphene nanoribbons and provide an\navenue towards tuning their properties via the structural and environmental\ndegrees of freedom."
    },
    {
        "anchor": "Coupled Layer Construction for Synthetic Hall Effects in Driven Systems: Quasiperiodically driven fermionic systems can support topological phases not\nrealized in equilibrium. The fermions are localized in the bulk, but support\nquantized energy currents at the edge. These phases were discovered through an\nabstract classification, and few microscopic models exist. We develop a coupled\nlayer construction for tight-binding models of these phases in $d\\in\\{1,2\\}$\nspatial dimensions, with any number of incommensurate drive frequencies $D$.\nThe models exhibit quantized responses associated with synthetic two- and\nfour-dimensional quantum Hall effects in the steady state. A numerical study of\nthe phase diagram for $(d+D) = (1+2)$ shows: (i) robust topological and trivial\nphases separated by a sharp phase transition; (ii) charge diffusion and a\nhalf-integer energy current between the drives at the transition; and (iii) a\nlong-lived topological energy current which remains present when weak\ninteractions are introduced.",
        "positive": "Emergent Chern-Simons Interactions in 3+1 Dimensions: Parity violating superconductors can support a low-dimension local\ninteraction that becomes, upon condensation, a purely spatial Chern-Simons\nterm. Solutions to the resulting generalized London equations can be obtained\nfrom solutions of the ordinary London equations with a complex penetration\ndepth, and suggest several remarkable physical phenomena. The problem of flux\nexclusion by a sphere brings in an anapole moment, the problem of\ncurrent-carrying wires brings in an azimuthal magnetic field, and the problem\nof vortices brings in currents along the vortices. We demonstrate that\ninteractions of this kind, together with a conceptually related dimensionally\nreduced Chern-Simons interaction, can arise from physically plausible\nmicroscopic interactions."
    },
    {
        "anchor": "Rabi oscillations, Ramsey fringes and spin echoes in an electrical\n  circuit: We present a superconducting tunnel junction circuit which behaves as a\ncontrollable atom, and whose ground and first excited state form an effective\nspin 1/2. By applying microwave pulses, we have performed on this circuit\nexperiments demonstrating the controlled manipulation of the spin : Rabi\nprecession, Ramsey interferences, and spin echoes.",
        "positive": "On-Chip Microwave Fock States and Quantum Homodyne Measurements: We propose a method to couple metastable flux-based qubits to superconductive\nresonators based on a quantum-optical Raman excitation scheme that allows for\nthe deterministic generation of stationary and propagating microwave Fock\nstates and other weak quantum fields. Moreover, we introduce a suitable\nmicrowave quantum homodyne technique, with no optical counterpart, that enables\nthe measurement of relevant field observables, even in the presence of noisy\namplification devices."
    },
    {
        "anchor": "Tunable Berry curvature, valley and spin Hall effect in Bilayer MoS$_2$: The chirality of electronic Bloch bands is responsible for many intriguing\nproperties of layered two-dimensional materials. We show that in bilayers of\ntransition metal dichalcogenides (TMDCs), unlike in few-layer graphene and\nmonolayer TMDCs, both intra-layer and inter-layer couplings give important\ncontributions to the Berry-curvature in the $K$ and $-K$ valleys of the\nBrillouin zone. The inter-layer contribution leads to the stacking dependence\nof the Berry curvature and we point out the differences between the commonly\navailable 3R type and 2H type bilayers. Due to the inter-layer contribution the\nBerry curvature becomes highly tunable in double gated devices. We study the\ndependence of the valley Hall and spin Hall effects on the stacking type and\nexternal electric field. Although the valley and spin Hall conductivities are\nnot quantized, in MoS$_2$ 2H bilayers they may change sign as a function of the\nexternal electric field which is reminiscent of the behaviour of lattice Chern\ninsulators.",
        "positive": "Surface electron mobility over a helium film: The mobility of surface electrons localized over helium films underlying\nsolid substrates has been evaluated by solving the Boltzmann equation in the\ntime relaxation approximation and the force balance equation in which an\neffective mobility is obtained in terms of the dynamical structure factor of\nthe nondegenerate electron liquid. The essential processes of electron\nscattering by gas atoms, ripplons, and film-solid interface roughness are taken\ninto account. The electron mobility dependence on the film thickness and\ntemperature is determined and compared with experimental data available. We\nfind that the interface-roughness scattering is the dominant process for\nexplaining the experimental results. We estimate the extended defect sizes of\nthe underlying substrate within the Gaussian correlated model for interface\nroughness."
    },
    {
        "anchor": "Scanning qubit probe of edge states in a topological insulator: In this work, we propose a novel qubit-based sensor with the ability to\ncharacterize topological edge states in low-dimensional systems. A composite\nsystem is studied, consisting of a qubit coupled to a topologically nontrivial\nSu-Schrieffer-Heeger chain between semi-infinite lead channels. This qubit\nprobe utilizes decoherence dynamics which, under a weak-coupling framework, are\nrelated to the environment's local density of states. Qubit decoherence rate\nmeasurements along a sample therefore provide the means to extract edge state\nprofiles. The environment's influence on the qubit's subspace is captured by an\neffective projective treatment, leading to an analytical decoherence rate\nexpression. We demonstrate that the scanning qubit probe identifies and yields\na complete spatial characterization of the topological edge states within the\ncomposite system.",
        "positive": "Two electrons in a strongly coupled double quantum dot: from an\n  artificial helium atom to a hydrogen molecule: We study the formation of molecular states in a two-electron quantum dot as a\nfunction of the barrier potential dividing the dot. The increasing barrier\npotential drives the two electron system from an artificial helium atom to an\nartificial hydrogen molecule. To study this strongly coupled regime, we\nintroduce variational wavefunctions which describe accurately two electrons in\na single dot, and then study their mixing induced by the barrier. The evolution\nof the singlet-triplet gap with the barrier potential and with an external\nmagnetic field is analyzed."
    },
    {
        "anchor": "Quantum Fluctuations and Long-Range Order in Molecular Magnets: We review our studies of the effect of transverse fields on the\nsusceptibility and magnetization of single crystals of the prototype single\nmolecule magnet (SMM), Mn$_{12}$-acetate, and of a new high-symmetry variant,\nMn$_{12}$-acetate-MeOH. SMM single crystals can exhibit long range\nferromagnetic order associated with intermolecular dipole interactions.\nTransverse fields increase quantum spin fluctuation and quantum tunneling of\nthe magnetization suppressing long range order. However, we have found that\nsuppression of the Curie temperature by a transverse field in Mn$_{12}$-acetate\nis far more rapid than predicted by the Transverse-Field Ising Ferromagnetic\nModel (TFIFM). It appears that solvent disorder in Mn$_{12}$-acetate that\nresults in an intrinsic distribution of small discrete tilts of the molecular\nmagnetic easy axis from the global easy axis of the crystal ($\\approx \\pm\n1^\\circ$) gives rise to a distribution of random-fields that further suppresses\nlong-range order. Semiquantitative agreement with the predictions of a\nRandom-Field Ising Ferromagnet Model is found. Subsequent susceptibility\nstudies we have conducted of the high symmetry Mn$_{12}$ variant,\nMn$_{12}$-acetate-MeOH, with the same spin structure and similar lattice\nconstants but without the same solvent disorder as Mn$_{12}$-acetate, agrees\nwith the TFIFM. An important implication of our studies is that long-range\norder in these two chemically very similar SMMs are described by distinct\nphysical models.",
        "positive": "Helical States in Curved Bilayer Graphene: We study spin effects of quantum wires formed in bilayer graphene by\nelectrostatic confinement. With a proper choice of the confinement direction,\nwe show that in the presence of magnetic field, spin-orbit interaction induced\nby curvature, and intervalley scattering, bound states emerge that are helical.\nThe localization length of these helical states can be modulated by the gate\nvoltage which enables the control of the tunnel coupling between two parallel\nwires. Allowing for proximity effect via an s-wave superconductor, we show that\nthe helical modes give rise to Majorana fermions in bilayer graphene."
    },
    {
        "anchor": "Dephasing in the semiclassical limit is system-dependent: We investigate dephasing in open quantum chaotic systems in the limit of\nlarge system size to Fermi wavelength ratio, $L/\\lambda_F >> 1$. We\nsemiclassically calculate the weak localization correction $g^{wl}$ to the\nconductance for a quantum dot coupled to (i) an external closed dot and (ii) a\ndephasing voltage probe. In addition to the universal algebraic suppression\n$g^{wl} \\propto (1+\\tau_D/\\tau_\\phi)^{-1}$ with the dwell time $\\tau_D$ through\nthe cavity and the dephasing rate $\\tau_\\phi^{-1}$, we find an exponential\nsuppression of weak localization by a factor $\\propto\n\\exp[-\\tilde{\\tau}/\\tau_\\phi]$, with a system-dependent $\\tilde{\\tau}$. In the\ndephasing probe model, $\\tilde{\\tau}$ coincides with the Ehrenfest time,\n$\\tilde{\\tau} \\propto \\ln [L/\\lambda_F]$, for both perfectly and partially\ntransparent dot-lead couplings. In contrast, when dephasing occurs due to the\ncoupling to an external dot, $\\tilde{\\tau} \\propto \\ln [L/\\xi]$ depends on the\ncorrelation length $\\xi$ of the coupling potential instead of $\\lambda_F$.",
        "positive": "Negative exchange interactions in coupled few-electron quantum dots: It has been experimentally shown that negative exchange interactions can\narise in a linear three-dot system when a two-electron double quantum dot is\nexchange coupled to a larger quantum dot containing on the order of one hundred\nelectrons. The origin of this negative exchange can be traced to the larger\nquantum dot exhibiting a spin triplet-like rather than singlet-like ground\nstate. Here, we show using a microscopic model based on the configuration\ninteraction (CI) method that both triplet-like and singlet-like ground states\nare realized depending on the number of electrons. In the case of only four\nelectrons, a full CI calculation reveals that triplet-like ground states occur\nfor sufficiently large dots. These results hold for symmetric and asymmetric\nquantum dots in both Si and GaAs, showing that negative exchange interactions\nare robust in few-electron double quantum dots and do not require large numbers\nof electrons."
    },
    {
        "anchor": "Spatial patterns of dissipative polariton solitons in semiconductor\n  microcavities: Semiconductor microcavities operating in the polaritonic regime are highly\nnon-linear, high speed systems due to the unique half-light, half-matter nature\nof polaritons. Here, we report for the first time the observation of\npropagating multi-soliton polariton patterns consisting of multi-peak\nstructures either along (x) or perpendicular to (y) the direction of\npropagation. Soliton arrays of up to 5 solitons are observed, with the number\nof solitons controlled by the size or power of the triggering laser pulse. The\nbreak-up along the x direction occurs due to interplay of bistability, negative\neffective mass and polariton-polariton scattering, while in the y direction the\nbreak-up results from nonlinear phase-dependent interactions of propagating\nfronts. We show the experimental results are in good agreement with numerical\nmodelling. Our observations are a step towards ultrafast all-optical signal\nprocessing using sequences of solitons as bits of information.",
        "positive": "Spiral vortices in a 2D ferromagnet: We present a study of a new class of exact solutions having a form of spiral\nvortices for an isotropic two-dimensional Heisenberg ferromagnet using a\ncontinuum theory and direct numerical simulations of the spin system on a\nsquare lattice. We find their features issued from the conservation laws and\ndescribe their interaction. Reasons behind the formation of the proper spin\nconfigurations on a square lattice are investigated."
    },
    {
        "anchor": "Monolithic Integrations of Slanted Silicon Nanostructures on 3D\n  Microstructures and Their Application to Surface Enhanced Raman Spectroscopy: We demonstrated fabrication of black silicon with slanted nanocone array on\nboth planar and 3D micro and meso scale structures produced by a\nhigh-throughput lithography-free oblique-angle plasma etching process.\nNanocones with gradual change in height were created on the same piece of\nsilicon. The relation between the slanted angle of nanocones and incident angle\nof directional plasma is experimentally investigated. In order to demonstrate\nthe monolithic integration of nanostructures on micro and meso scale non-planar\nsurfaces, nanocone forest is fabricated on non-planar silicon surfaces in\nvarious morphologies such as silicon atomic force microscopy (AFM) tips and\npyramidal pits. By integrating nanocones on inverse silicon micro-pyramid array\ndevices, we further improved the surface enhanced Raman scattering (SERS)\nenhancement property of this optimized commercial SERS substrate by several\nfolds even when using 66% less noble metal coating. We investigated the length\ngradient dependence and asymmetric properties of SERS effects for slanted\nnanocone with polarized excitation. This versatile and angle-controllable\nnanocone fabrication and monolithic 3D nano-micro-meso integration method\nprovides new dimensions for production and optimization of SERS and other\nnanophotonic sensors.",
        "positive": "Stacking enabled strong coupling of atomic motion to interlayer excitons\n  in van der Waals heterojunction photodiodes: We reveal stacking-induced strong coupling between atomic motion and\ninterlayer excitons through photocurrent measurements of WSe$_2$/MoSe$_2$\nheterojunction photodiodes. Strong coupling manifests as pronounced periodic\nsidebands in the photocurrent spectrum in frequency windows close to the\ninterlayer exciton resonances. The sidebands, which repeat over large swathes\nof the interlayer exciton photocurrent spectrum, occur in energy increments\ncorresponding directly to a prominent vibrational mode of the heterojunction.\nSuch periodic patterns, together with interlayer photoconductance oscillations,\nvividly demonstrate the emergence of extraordinarily strong exciton-phonon\ncoupling - and its impact on interlayer excitations - in stack-engineered van\nder Waals heterostructure devices. Our results establish photocurrent\nspectroscopy as a powerful tool for interrogating vibrational coupling to\ninterlayer excitons and suggest an emerging strategy to control vibronic\nphysics in the solid-state."
    },
    {
        "anchor": "Coexistence of Interfacial Stress and Charge Transfer in Graphene Oxide\n  based Magnetic Nanocomposites: In this paper, we establish the existence of both compressive stress and\ncharge transfer process in hydrothermally synthesized cobalt ferrite-graphene\noxide (CoFe2O4/GO) nanocomposites. Transmission electron microscopy (TEM)\nresults reveal the decoration of CoFe2O4 nanoparticles on GO sheets. Magnetic\nresponse of nanocomposites was confirme from superconducting quantum\ninterference device (SQUID) magnetometer measurement. Optical properties of\nthese nanocomposites were investigated by Raman spectroscopy. Interfacial\ncompressive stress involved in this system is evaluated from observed blue\nshift of characteristic G peak of graphene oxide. Increase in full width\nhalf-maximum ( FWHM) as well as up shift in D and G peaks are clear indicator\nof involvement of charge transfer process between GO sheets and dispersed\nmagnetic nanoparticles. The effect of charge transfer process is quantified in\nterms of shifting of Fermi level of these nanocomposites. This is evaluated\nfrom variation in contact surface potential difference (CPD) using Scanning\nKelvin probe microscopy (SKPM). XRD spectra of CoFe2O4/GO confirm the\npolycrystalline nature of CoFe2O4 nanoparticles. Lattice strain estimated from\nXRD peaks are correlated to the observed Raman shift.",
        "positive": "Two-species percolation and Scaling theory of the metal-insulator\n  transition in two dimensions: Recently, a simple non-interacting-electron model, combining local quantum\ntunneling via quantum point contacts and global classical percolation, has been\nintroduced in order to describe the observed ``metal-insulator transition'' in\ntwo dimensions [1]. Here, based upon that model, a two-species-percolation\nscaling theory is introduced and compared to the experimental data. The two\nspecies in this model are, on one hand, the ``metallic'' point contacts, whose\ncritical energy lies below the Fermi energy, and on the other hand, the\ninsulating quantum point contacts. It is shown that many features of the\nexperiments, such as the exponential dependence of the resistance on\ntemperature on the metallic side, the linear dependence of the exponent on\ndensity, the $e^2/h$ scale of the critical resistance, the quenching of the\nmetallic phase by a parallel magnetic field and the non-monotonic dependence of\nthe critical density on a perpendicular magnetic field, can be naturally\nexplained by the model.\n  Moreover, details such as the nonmonotonic dependence of the resistance on\ntemperature or the inflection point of the resistance vs. parallel magnetic are\nalso a natural consequence of the theory. The calculated parallel field\ndependence of the critical density agrees excellently with experiments, and is\nused to deduce an experimental value of the confining energy in the vertical\ndirection. It is also shown that the resistance on the ``metallic'' side can\ndecrease with decreasing temperature by an arbitrary factor in the degenerate\nregime ($T\\lesssim E_F$)."
    },
    {
        "anchor": "Spatially resolved femtosecond pump-probe study of topological insulator\n  Bi2Se3: Carrier and phonon dynamics in Bi2Se3 crystals are studied by a spatially\nresolved ultrafast pump-probe technique. Pronounced oscillations in\ndifferential reflection are observed with two distinct frequencies, and are\nattributed to coherent optical and acoustic phonons, respectively. The rising\ntime of the signal indicates that the thermalization and energy relaxation of\nhot carriers are both sub-ps in this material. We found that the thermalization\nand relaxation time decreases with the carrier density. The expansion of the\ndifferential reflection profile allows us to estimate an ambipolar carrier\ndiffusion coefficient on the order of 500 square centimeters per second. A\nlong-term slow expansion of the profile shows a thermal diffusion coefficient\nof 1.2 square centimeters per second.",
        "positive": "Transport Theory of Monolayer Transition-Metal Dichalcogenides through\n  Symmetry: We present a theory that elucidates the major momentum and spin relaxation\nprocesses for electrons, holes and hot excitons in monolayer transition-metal\ndichalcogenides. We expand on spin flips induced by flexural phonons and show\nthat the spin relaxation is ultrafast for electrons in free-standing membranes\nwhile being mitigated in supported membranes. This behavior due to interaction\nwith flexural phonons is universal in two-dimensional membranes that respect\nmirror symmetry and it leads to a counterintuitive inverse relation between\nmobility and spin relaxation."
    },
    {
        "anchor": "Deflation algorithm for the Green function of quasi-1D lattices: We derive a method to efficiently compute the Green function of on arbitrary\nHamiltonians defined on semi-infinite and periodic quasi-one-dimensional\nlattices. Computing the Green function is the backbone of quantum transport,\nelectronic structure or linear response computations. Our method constitutes a\n\"deflation optimization\" of a well established algorithm often used in quantum\ntransport that is based on generalized Schur factorizations of the linearized\nquadratic eigenvalue equation for the transfer matrix. Our deflation\noptimization may greatly reduce the number of degrees of freedom that must be\nprocessed in the Schur factorization. Deflation must be supplemented by a\nJordan-block reconstruction of generalized eigenvectors, also developed here in\ndetail. The overhead of deflation plus reconstruction is minimal as compared to\nthe typical reduction in factorization runtime. Furthermore, by avoiding\ninverses of ill-conditioned matrices, the algorithm remains numerically stable.",
        "positive": "Electrically Driven Hot-Carrier Generation and Above-threshold Light\n  Emission in Plasmonic Tunnel Junctions: Above-threshold light emission from plasmonic tunnel junctions, when emitted\nphotons have energies significantly higher than the energy scale of the\nincident electrons, has attracted much recent interest in nano-optics, while\nthe underlying physical mechanism remains elusive. We examine above-threshold\nlight emission in electromigrated tunnel junctions. Our measurements over a\nlarge ensemble of devices demonstrate a giant material dependence of photon\nyield (emitted photons per incident electrons), as large as four orders of\nmagnitude. This dramatic effect cannot be explained only by the radiative field\nenhancement effect due to the localized plasmons in the tunneling gap. Emission\nis well described by a Boltzmann spectrum with an effective temperature\nexceeding 2000 K, coupled to a plasmon-modified photonic density of states. The\neffective temperature is approximately linear in the applied bias, consistent\nwith a suggested theoretical model in which hot carriers are generated by\nnon-radiative decay of electrically excited localized plasmons. Electrically\ndriven hot-carrier generation and the associated non-traditional light emission\ncould open new possibilities for active photochemistry, optoelectronics and\nquantum optics."
    },
    {
        "anchor": "Intrinsic magnetic topological insulators: Introducing magnetism into topological insulators breaks time-reversal\nsymmetry, and the magnetic exchange interaction can open a gap in the otherwise\ngapless topological surface states. This allows various novel topological\nquantum states to be generated, including the quantum anomalous Hall effect\n(QAHE) and axion insulator states. Magnetic doping and magnetic proximity are\nviewed as being useful means of exploring the interaction between topology and\nmagnetism. However, the inhomogeneity of magnetic doping leads to complicated\nmagnetic ordering and small exchange gaps, and consequently the observed QAHE\nappears only at ultralow temperatures. Therefore, intrinsic magnetic\ntopological insulators are highly desired for increasing the QAHE working\ntemperature and for investigating topological quantum phenomena further. The\nrealization and characterization of such systems are essential for both\nfundamental physics and potential technical revolutions. This review summarizes\nrecent research progress in intrinsic magnetic topological insulators, focusing\nmainly on the antiferromagnetic topological insulator MnBi2Te4 and its family\nof materials.",
        "positive": "Non-Born effects in scattering of electrons in a conducting strip with\n  low concentration of impurities: We extend the theory of non-Born effects in resistivity $\\rho$ of clean\nconducting tubes (developed in our previous work arXiv:1810.00426) to\n``strips'' -- quasi-one-dimensional structures in 2D conductors. Here also an\noriginal Van Hove singularity in dependence of $\\rho$ on the position of\nchemical potential $\\varepsilon$ is asymmetrically split in two peaks for\nattracting impurities. However, since amplitudes of scattering at impurities\ndepend on their positions, these peaks are inhomogeneously broadened. Strongest\nbroadening occurs in the left peak, arising, for attracting impurities, due to\nscattering at quasistationary levels. In contrast with the case of tube these\nlevels form not a unique sharp line, but a relatively broad impurity band with\na weak quasi-Van Hove feature on its lower edge. Different parts of\n$\\rho(\\varepsilon)$ are dominated by different groups of impurities: close to\nthe minimum the most effective scatterers, paradoxically are the ``weakest''\nimpurities -- those, located close to nodes of the electronic wave-function, so\nthat the bare scattering matrix elements are suppressed. The quasi-Van Hove\nfeature at left maximum is dominated by strongest impurites, located close to\nantinodes."
    },
    {
        "anchor": "Atomistic potentials and the Cauchy-Born rule for carbon nanotubes: a\n  review: Carbon nanotubes are modeled as point particle configurations in the\nframework of Molecular Mechanics, where interactions are described by means of\nshort range attractive-repulsive potentials. The identification of local energy\nminimizers yields a variational description for the stability of rolled-up\nhexagonal-lattice structures. Optimality of periodic configurations is\npreserved under moderate tension, hence justifying the elastic behavior of\ncarbon nanotubes in the axial traction regime.",
        "positive": "Axion optical induction of antiferromagnetic order: Using circularly-polarized light to control quantum matter is a highly\nintriguing topic in physics, chemistry and biology. Previous studies have\ndemonstrated helicity-dependent optical control of spatial chirality and\nmagnetization $M$. The former is central for asymmetric synthesis in chemistry\nand homochirality in bio-molecules, while the latter is of great interest for\nferromagnetic spintronics. In this paper, we report the surprising observation\nof helicity-dependent optical control of fully-compensated antiferromagnetic\n(AFM) order in 2D even-layered MnBi$_2$Te$_4$, a topological Axion insulator\nwith neither chirality nor $M$. We further demonstrate helicity-dependent\noptical creation of AFM domain walls by double induction beams and the direct\nreversal of AFM domains by ultrafast pulses. The control and reversal of AFM\ndomains and domain walls by light helicity have never been achieved in any\nfully-compensated AFM. To understand this optical control, we study a novel\ntype of circular dichroism (CD) proportional to the AFM order, which only\nappears in reflection but is absent in transmission. We show that the optical\ncontrol and CD both arise from the optical Axion electrodynamics, which can be\nvisualized as a Berry curvature real space dipole. Our Axion induction provides\nthe possibility to optically control a family of $\\mathcal{PT}$-symmetric AFMs\nsuch as Cr$_2$O$_3$, CrI$_3$ and possibly novel states in cuprates. In\nMnBi$_2$Te$_4$, this further opens the door for optical writing of\ndissipationless circuit formed by topological edge states."
    },
    {
        "anchor": "Indirect Interaction of Magnetic Domain Walls: We calculate the electron-mediated exchange interaction between two domain\nwalls in magnetic wires. This corresponds to the equilibrium regime and,\ntherefore, the interaction can be additionally controlled by an electric\ncurrent. The exchange interaction is long ranged and oscillates as a function\nof the distance between the walls. It also depends oscillatory on the\npolarization angle of the walls, having the maximum value for collinear\npolarization.",
        "positive": "Minimum light transmission in graphene in the presence of a magnetic\n  field: We show that, on general theoretical grounds, transmission of light in\ngraphene always presents a non-vanishing minimum value independently of any\nmaterial and physical condition, the transmission coefficient being higher in\nthe presence of a substrate, and getting increasing when QED corrections higher\nthan alpha come into play. Explicit numerical calculations for typical cases\nare carried out when an external magnetic field is applied to the sample,\nshowing that, in epitaxial graphene, a threshold effect exists leading to a non\ntrivial minimum transmission, for a non vanishing light frequency, only for\nfield values larger than a critical one, both in the large and in the\nintermediate chemical potential regime. Such a threshold effect manifests even\nin the maximum Faraday rotation polarization of light, which is substantially\ncontrolled by the applied magnetic field. Instead, more transmission minima in\nsuspended graphene enters in the considered light frequency region for\nincreasing magnetic field, displaying an effective shift of frequency bands\nwhere the sample gets more or less absorptive with a suitable tuning of the\nexternal field. Two transition regions in different magnetic field ranges are\nfound, where the shift effect towards higher frequency values occurs both in\nthe transmission coefficient and in the Faraday rotation angle. Potential\ntechnological application of the results presented are envisaged."
    },
    {
        "anchor": "Casimir induced instabilities at metallic surfaces and interfaces: Surface plasmons subject to a surface distortion split asymmetrically in\nenergy resulting in a net lowering of zero-point energy. This is because\nsurface plasmon eigenvalues are the square of frequencies, a statement\ngenerally true for electromagnetic excitations. We utilize the method based on\nconformal mapping to demonstrate asymmetric splitting under surface\ncorrugations leading to a decrease in zero-point energy of a single corrugated\nmetallic surface contributing to surface reconstructions but too small on its\nown to drive the reconstruction. However, by introducing a second metallic\nsurface more significant lowering of energy is seen sufficient to drive the\ninstability of a mercury thin film.",
        "positive": "Non-Markovian effects at the Fermi-edge singularity in quantum dots: We study electronic transport through a quantum dot in the Fermi-edge\nsingularity regime, placing emphasis on its non-Markovian attributes. These are\nquantified by the behavior of current noise as well as trace-distance-based\nmeasure of non-Markovianity and found to be pronounced at low temperatures\nwhere the interplay of many-electron correlations and quantum coherence present\nin the system leads to significant quantum memory effects and non-Markovian\ndynamics."
    },
    {
        "anchor": "Asymmetric graphene model applied to graphite-like carbon-based\n  ferromagnetism: Several experiments have recently found room-temperature ferromagnetism in\ngraphite-like carbon based materials. This paper offers a model explaining such\nferromagnetism by using an asymmetric nano-graphene. Our first typical model is\nC48H24 graphene molecule, which has three dihydrogenated (-CH2) zigzag edges.\nThere are several multiple spin states competing for stable minimum energy in\nthe same atomic topology. Both molecular orbital and density function theory\nmethods indicate that the quartet state(S=3/2) is more stable than that of\ndoublet (S=1/2), which means that larger saturation magnetization will be\nachieved. We also enhanced this molecule to an infinite length ribbon having\nmany (-CH2) edges. Similar results were obtained where the highest spin state\nwas more stable than lower spin state. In contrast, a nitrogen substituted\n(-NH) molecule C45N3H21 demonstrated opposite results. that is, the lowest spin\nstate(S=1/2) is more stable than that of highest one(S=3/2), which arises from\nthe slight change in atom position.",
        "positive": "Local and Nonlocal Transport Spectroscopy in Planar Josephson Junctions: We report simultaneously acquired local and nonlocal transport spectroscopy\nin a phase-biased planar Josephson junction based on an epitaxial InAs/Al\nhybrid two-dimensional heterostructure. Quantum point contacts at the junction\nends allow measurement of the 2 x 2 matrix of local and nonlocal tunneling\nconductances as a function of magnetic field along the junction, phase\ndifference across the junction, and carrier density. A closing and reopening of\na gap was observed in both the local and nonlocal tunneling spectra as a\nfunction of magnetic field. For particular tunings of junction density, gap\nreopenings were accompanied by zero-bias conductance peaks (ZBCPs) in local\nconductances. End-to-end correlation of gap reopening was strong, while\ncorrelation of local ZBCPs was weak. A simple, disorder-free model of the\ndevice shows comparable conductance matrix behavior associated with a\ntopological phase transition. Phase dependence helps distinguish possible\norigins of the ZBCPs."
    },
    {
        "anchor": "Embedded Topological Insulators: We present a generalization of free fermionic topological insulators that are\ncomposed of topological subsystems of differing dimensionality. We specifically\nfocus on topological subsystems of nonzero co-dimension are embedded within a\ntrivial insulating environment. A general procedure is described to isolate and\nclassify such embedded topological insulators and we present three\nrepresentative examples in varying dimensions and symmetry classes. Moreover,\nwe demonstrate with concrete examples that the presence of periodically\nembedded topological insulators in an otherwise trivially classified system can\nlead to topologically non-trivial physical phenomena on crystalline defects;\nnamely, novel topological surface/edge modes at stacking faults and partial\nedge dislocations.",
        "positive": "Photostrictive two-dimensional materials in the monochalcogenide family: Photostriction is predicted for SnS and SnSe monolayers, two-dimensional\nferroelectrics with rectangular unit cells (the lattice vector $\\mathbf{a}_1$\nis larger than $\\mathbf{a}_2$) and an intrinsic dipole moment parallel to\n$\\mathbf{a}_1$. Photostriction in these two-dimensional materials is found to\nbe induced by a screened electric polarization in the photoexcited electronic\nstate (i.e., a converse piezoelectric effect) that leads to a compression of\n$a_1$ and a comparatively smaller increase of $a_2$ for a reduced unit cell\narea. The structural change documented here is ten times larger than that\nobserved in BiFeO$_3$, making monochalcogenide monolayers an ultimate platform\nfor this effect. This structural modification should be observable under\nexperimentally feasible densities of photexcited carriers on samples that have\nbeen grown already, having a potential usefulness for light-induced, remote\nmechano-opto-electronic applications."
    },
    {
        "anchor": "Perturbation theory for two-dimensional hydrodynamic plasmons: Perturbation theory is an indispensable tool in quantum mechanics and\nelectrodynamics that handles weak effects on particle motion or fields.\nHowever, its extension to plasmons involving complex motion of {\\it both}\nparticles and fields remained challenging. We show that this challenge can be\nmastered if electron motion obeys the laws of hydrodynamics, as recently\nconfirmed in experiments with ultra-clean heterostructures. We present a\nunified approach to evaluate corrections to plasmon spectra induced by carrier\ndrift, magnetic field, Berry curvature, scattering, and viscosity. As a first\napplication, we study the stability of direct current in confined\ntwo-dimensional electron systems against self-excitation of plasmons. We show\nthat arbitrarily weak current in the absence of dissipation is unstable\nprovided the structure lacks mirror symmetry. As a second application, we\nindicate that in extended periodic systems -- plasmonic crystals -- carrier\ndrift induces anomalous Doppler shift, which can be both below and higher than\nits value in uniform systems. Finally, we exactly evaluate the effect of Berry\ncurvature on spectra of edge plasmons and demonstrate the non-reciprocity\ninduced by anomalous velocity.",
        "positive": "Wigner time-delay distribution in chaotic cavities and freezing\n  transition: Using the joint distribution for proper time-delays of a chaotic cavity\nderived by Brouwer, Frahm & Beenakker [Phys. Rev. Lett. {\\bf 78}, 4737 (1997)],\nwe obtain, in the limit of large number of channels $N$, the large deviation\nfunction for the distribution of the Wigner time-delay (the sum of proper\ntimes) by a Coulomb gas method. We show that the existence of a power law tail\noriginates from narrow resonance contributions, related to a (second order)\nfreezing transition in the Coulomb gas."
    },
    {
        "anchor": "Conductance Quantization and Magnetoresistance in Magnetic Point\n  Contacts: We theoretically study the electron transport through a magnetic point\ncontact (PC) with special attention to the effect of an atomic scale domain\nwall (DW). The spin precession of a conduction electron is forbidden in such an\natomic scale DW and the sequence of quantized conductances depends on the\nrelative orientation of magnetizations between left and right electrodes. The\nmagnetoresistance is strongly enhanced for the narrow PC and oscillates with\nthe conductance.",
        "positive": "Mach--Zehnder-like interferometry with graphene nanoribbon networks: We study theoretically electron interference in a Mach--Zehnder-like geometry\nformed by four zigzag graphene nanoribbons (ZGNRs) arranged in parallel pairs,\none on top of the other, such that they form intersection angles of 60$^\\circ$.\nDepending on the interribbon separation, each intersection can be tuned to act\neither as an electron beam splitter or as a mirror, enabling tuneable circuitry\nwith interfering pathways. Based on the mean-field Hubbard model and Green's\nfunction techniques, we evaluate the electron transport properties of such\n8-terminal devices and identify pairs of terminals that are subject to\nself-interference. We further show that the scattering matrix formalism in the\napproximation of independent scattering at the four individual junctions\nprovides accurate results as compared with the Green's function description,\nallowing for a simple interpretation of the interference process between two\ndominant pathways. This enables us to characterize the device sensitivity to\nphase shifts from an external magnetic flux according to the Aharonov--Bohm\neffect as well as from small geometric variations in the two path lengths. The\nproposed devices could find applications as magnetic field sensors and as\ndetectors of phase shifts induced by local scatterers on the different\nsegments, such as adsorbates, impurities or defects. The setup could also be\nused to create and study quantum entanglement."
    },
    {
        "anchor": "Electron-phonon coupling in metallic carbon nanotubes: Dispersionless\n  electron propagation despite dissipation: A recent study [Rosati, Dolcini, and Rossi, Appl. Phys. Lett. 106, 243101\n(2015)] has predicted that, while in semiconducting single-walled carbon\nnanotubes (SWNTs) an electronic wave packet experiences the typical spatial\ndiffusion of conventional materials, in metallic SWNTs its shape remains\nessentially unaltered up to micron distances at room temperature, even in the\npresence of the electron-phonon coupling. Here, by utilizing a Lindblad-based\ndensity-matrix approach enabling us to account for both dissipation and\ndecoherence effects, we test such prediction by analyzing various aspects that\nwere so far unexplored. In particular, accounting for initial nonequilibrium\nexcitations, characterized by an excess energy $E_0$, and including both intra-\nand interband phonon scattering, we show that for realistically high values of\n$E_0$ the electronic diffusion is extremely small and nearly independent of its\nenergetic distribution, in spite of a significant energy-dissipation and\ndecoherence dynamics. Furthermore, we demonstrate that the effect is robust\nwith respect to the variation of the chemical potential. Our results thus\nsuggest that metallic SWNTs are a promising platform to realise quantum\nchannels for the non-dispersive transmission of electronic wave packets.",
        "positive": "Dielectric anomaly in coupled rotor systems: The correlated dynamics of coupled quantum rotors carrying electric dipole\nmoment is theoretically investigated. The energy spectra of coupled rotors as a\nfunction of dipolar interaction energy is analytically solved. The calculated\ndielectric susceptibilities of the system show the peculiar temperature\ndependence different from that of isolated rotors."
    },
    {
        "anchor": "Charge conservation breaking within generalized master equation\n  description of electronic transport through dissipative double quantum dots: We report an observation of charge conservation breaking in a model study of\nelectronic current noise of transport through a dissipative double quantum dot\nwithin generalized master equation formalism. We study the current noise\nthrough a double quantum dot coupled to two electronic leads in the high bias\nlimit and a dissipative heat bath in the weak coupling limit. Our calculations\nare based on the solution of a Markovian generalized master equation.\nZero-frequency component of the current noise calculated within the system,\ni.e., between the two dots, via the quantum regression theorem exhibits\nunphysical negative values. On the other hand, current noise calculated for\ncurrents between the dots and the leads by the counting variable approach shows\nno anomalies and seems physically plausible. We inquire into the origin of this\ndiscrepancy between two nominally equivalent approaches and show that it stems\nfrom the simultaneous presence of the two types of baths, i.e., the electronic\nleads and the dissipative bosonic bath. This finding raises interesting\nquestions concerning conceptual foundations of the theory describing\nmultiple-baths open quantum systems widely encountered in nanoscience.",
        "positive": "Scattering phase shifts in quasi-one-dimension: Scattering of an electron in quasi-one dimensional quantum wires have many\nunusual features, not found in one, two or three dimensions. In this work we\nanalyze the scattering phase shifts due to an impurity in a multi-channel\nquantum wire with special emphasis on negative slopes in the scattering phase\nshift versus incident energy curves and the Wigner delay time. Although at\nfirst sight, the large number of scattering matrix elements show phase shifts\nof different character and nature, it is possible to see some pattern and\nunderstand these features. The behavior of scattering phase shifts in\none-dimension can be seen as a special case of these features observed in\nquasi-one-dimensions. The negative slopes can occur at any arbitrary energy and\nFriedel sum rule is completely violated in quasi-one-dimension at any arbitrary\nenergy and any arbitrary regime. This is in contrast to one, two or three\ndimensions where such negative slopes and violation of Friedel sum rule happen\nonly at low energy where the incident electron feels the potential very\nstrongly (i.e., there is a very well defined regime, the WKB regime, where FSR\nworks very well). There are some novel behavior of scattering phase shifts at\nthe critical energies where $S$-matrix changes dimension."
    },
    {
        "anchor": "Enhanced Weiss oscillations in graphene: The magneto-conductivity of a single graphene layer where the electrons are\ndescribed by the Dirac Hamiltonian weakly modulated by a periodic potential is\ncalculated. It is shown that Weiss oscillations periodic in the inverse\nmagnetic field appear, that are more pronounced and less damped with the\nincrement of temperature as compared with the same oscillations in a typical\ntwo-dimensional electron system with a standard parabolic energy spectrum.",
        "positive": "Establishing a non-Fermi liquid theory for disordered metals near two\n  dimensions: We consider the finkelstein action describing a system of spin polarized or\nspinless electrons near two dimensions, in the presence of disorder as well as\nthe Coulomb interactions.We extend the renormalization group analysis of our\nprevious work and evaluate the metal-insulator transition of the electron gas\nto second order in an (d-2) expansion. We obtain the complete scaling behavior\nof physical observables like the conductivity and the specific heat with\nvarying frequency, temperature and/or electron density."
    },
    {
        "anchor": "Understanding the saturation power of Josephson Parametric Amplifiers\n  made from SQUIDs arrays: We report on the implementation and detailed modelling of a Josephson\nParametric Amplifier (JPA) made from an array of eighty Superconducting QUantum\nInterference Devices (SQUIDs), forming a non-linear quarter-wave resonator.\nThis device was fabricated using a very simple single step fabrication process.\nIt shows a large bandwidth (45 MHz), an operating frequency tunable between 5.9\nGHz and 6.8 GHz and a large input saturation power (-117 dBm) when biased to\nobtain 20 dB of gain. Despite the length of the SQUID array being comparable to\nthe wavelength, we present a model based on an effective non-linear LC series\nresonator that quantitatively describes these figures of merit without fitting\nparameters. Our work illustrates the advantage of using array-based JPA since a\nsingle-SQUID device showing the same bandwidth and resonant frequency would\ndisplay a saturation power 15 dB lower.",
        "positive": "An in-situ tunable radio-frequency quantum point contact: Incorporating a variable capacitance diode into a radio-frequency matching\ncircuit allows us to in-situ tune the resonance frequency of an RF quantum\npoint contact, increasing the versatility of the latter as a fast charge sensor\nof a proximal quantum circuit. The performance of this method is compared in\ndetail to conventional low-frequency charge detection. The approach is also\napplicable to other RF-detection schemes, such as RF-SET circuits."
    },
    {
        "anchor": "Spin Hall Effect: The intrinsic spin Hall effect in semiconductors has developed to a\nremarkably lively and rapidly growing branch of research in the field of\nsemiconductor spintronics. In this article we give a pedagogical overview on\nboth theoretical and experimental accomplishments and challenges. Emphasis is\nput on the the description of the intrinsic mechanisms of spin Hall transport\nin III-V zinc-blende semiconductors, and on the effects of dissipation.",
        "positive": "Magnetomechanical coupling and ferromagnetic resonance in magnetic\n  nanoparticles: We address the theory of the coupled lattice and magnetization dynamics of\nfreely suspended single-domain nanoparticles. Magnetic anisotropy generates\nlow-frequency satellite peaks in the microwave absorption spectrum and a\nblueshift of the ferromagnetic resonance (FMR) frequency. The low-frequency\nresonances are very sharp with maxima exceeding that of the FMR, because their\nmagnetic and mechanical precessions are locked, thereby suppressing Gilbert\ndamping. Magnetic nanoparticles can operate as nearly ideal motors that convert\nelectromagnetic into mechanical energy. The Barnett/Einstein-de Haas effect is\nsignificant even in the absence of a net rotation."
    },
    {
        "anchor": "Valley polarization of exciton-polaritons in monolayer WSe2 in a tunable\n  microcavity: Monolayer transition metal dichalcogenides, known for exhibiting strong\nexcitonic resonances, constitute a very interesting and versatile platform for\ninvestigation of light-matter interactions. In this work we report on a strong\ncoupling regime between excitons in monolayer WSe2 and photons confined in an\nopen, voltage-tunable dielectric microcavity. The tunability of our system\nallows us to extend the exciton-polariton state over a wide energy range and,\nin particular, to bring the excitonic component of the lower polariton mode\ninto resonance with other excitonic transitions in monolayer WSe2. With\nselective excitation of spin-polarized exciton-polaritons we demonstrate the\nvalley polarization when the polaritons from the lower branch come into\nresonance with a bright trion state in monolayer WSe2 and valley depolarization\nwhen they are in resonance with a dark trion state.",
        "positive": "Independent dynamic acousto-mechanical and electrostatic control of\n  individual quantum dots in a LiNbO$_{3}$-GaAs hybrid: We demonstrate tuning of single quantum dot emission lines by the combined\naction of the dynamic acoustic field of a radio frequency surface acoustic wave\nand a static electric field. Both tuning parameters are set all-electrically in\na LiNbO$_{3}$-GaAs hybrid device. The surface acoustic wave is excited directly\non the strong piezoelectric LiNbO$_{3}$ onto which a GaAs-based p-i-n\nphotodiode containing a single layer of quantum dots was epitaxially\ntransferred. We demonstrate dynamic spectral tuning with bandwidths exceeding 3\nmeV of single quantum dot emission lines due to deformation potential coupling.\nThe center energy of the dynamic spectral oscillation can be independently\nprogrammed simply by setting the bias voltage applied to the diode."
    },
    {
        "anchor": "Generation and detection of dissipationless spin current in MgO/Si\n  bilayer: Spintronics is an analogue to electronics where spin of the electron rather\nthan its charge is functionally controlled for devices. The generation and\ndetection of spin current without ferromagnetic or exotic/scarce materials are\ntwo the biggest challenges for spintronics devices. In this study, we report a\nsolution to the two problems of spin current generation and detection in Si.\nUsing non-local measurement, we experimentally demonstrate the generation of\nhelical dissipationless spin current using spin-Hall effect. Contrary to the\ntheoretical prediction, we observe the spin-Hall effect in both n-doped and\np-doped Si. The helical spin current is attributed to the site-inversion\nasymmetry of the diamond cubic lattice of Si and structure inversion asymmetry\nin MgO/Si bilayer. The spin to charge conversion in Si is insignificant due to\nweak spin-orbit coupling. For the efficient detection of spin current, we\nreport spin to charge conversion at the MgO (1nm)/Si (2 um) (p-doped and\nn-doped) thin film interface due to Rashba spin-orbit coupling. We detected the\nspin current at a distance of >100 um, which is an order of magnitude larger\nthan the longest spin diffusion length measured using spin injection\ntechniques. The existence of spin current in Si is verified from coercivity\nreduction in Co/Pd multilayer due to spin-orbit torque generated by spin\ncurrent from Si.",
        "positive": "Size Dependence of Current-Voltage Properties in Coulomb Blockade\n  Networks: We theoretically investigate the current-voltage (I-V) property of\ntwo-dimensional Coulomb blockade (CB) arrays by conducting Monte Carlo\nsimulations. The I-V property can be divided into three regions and we report\nthe dependence of the aspect ratio delta (namely, the lateral size N_{y} over\nthe longitudinal one N_{x}). We show that the average CB threshold obeys a\npower-law decay as a function of delta. Its exponent gamma corresponds to a\nsensitivity of the threshold depending on delta, and is inversely proportional\nto N_{x} (i.e., delta at fixed N_{y}). Further, the power-law exponent zeta,\ncharacterizing the nonlinearity of the I-V property in the intermediate region,\nlogarithmically increases as delta increases. Our simulations describe the\nexperimental result zeta=2.25 obtained by Parthasarathy et al. [Phys. Rev.\nLett. 87 (2001) 186807]. In addition, the asymptotic I-V property of\none-dimensional arrays obtained by Bascones et al. [Phys. Rev. B. 77 (2008)\n245422] is applied to two-dimensional arrays. The asymptotic equation converges\nto the Ohm's law at the large voltage limit, and the combined\ntunneling-resistance is inversely proportional to delta. The extended\nasymptotic equation with the first-order perturbation well describes the\nexperimental result obtained by Kurdak et al. [Phys. Rev. B 57 (1998) R6842].\nBased on our asymptotic equation, we can estimate physical values that it is\nhard to obtain experimentally."
    },
    {
        "anchor": "Optical properties of graphene quantum dots: the role of chiral symmetry: We analyse the electronic and optical properties of graphene quantum dots\n(GQD) using accurate \\textit{ab initio} many-body $GW$ and Bethe-Salpeter\ncalculations. We show that most pristine GQD, including structures with\nirregular shapes, are characterized by dark low energy singlet excitations that\nquench fluorescence. We rationalizqe this property by exploiting the chiral\nsymmetry of the low energy electronic states in graphene. Edge \\textit{sp}$^3$\nfunctionalization is shown to efficiently brighten these low lying excitations\nby distorting the \\textit{sp}$^2$ backbone planar symmetry. Such findings\nreveal an original indirect scenario for the influence of functionalization on\nthe photoluminescence properties.",
        "positive": "Topological states on uneven (Pb,Sn)Se (001) surfaces: The impact of surface morphology on electronic structure of topological\ncrystalline insulators is studied theoretically. As an example, the structure\nof topologically protected electronic states on a (001) (Pb,Sn)Se surface with\nterraces of atomic height is modeled. Within the envelope function model it is\nshown that valley mixing, the phenomenon responsible for the peculiar \"double\nDirac cone\" shape of the surface state dispersion, depends crucially on the\nstructure of the surface. By varying the width and the number of atomic layers\nin the terraces, a comprehensive explanation of recent experimental findings,\ni.e., the emergence of 1D states bound to odd-height atomic step edges as well\nas the collapse of \"double Dirac cone\" structure on a rough surface, is\nachieved. This approach allows us also to determine topological indices\ncharacterizing terraces and their interfaces. In the (001) surface of (Pb,Sn)Se\nthe adjacent terraces turn out to be described by different values of the\nwinding number topological invariant."
    },
    {
        "anchor": "Voltage and dephasing probes: a full counting statistics discussion: Voltage and dephasing probes introduce incoherent inelastic and incoherent\nquasi-elastic scattering into a coherent mesoscopic conductor. We discuss in\ndetail the concepts of voltage and dephasing probes and develop a full counting\nstatistics approach to investigate their effect on the transport statistics.\nThe formalism is applied to several experimentally relevant examples. A\ncomparison of different probe models and with procedures like phase averaging\nover an appropriate phase distribution shows that there is a perfect\nequivalence between the models for the case of one single-channel probe.\nInterestingly, the appropriate phase distribution function is found to be\nuniform. A uniform distribution is provided by a chaotic cavity with a long\ndwell time. The dwell time of a chaotic cavity plays a role similar to the\ncharge response time of a voltage or dephasing probe. For multi-channel or\nmultiple probes the transport statistics of voltage and dephasing probes\ndiffers and the equivalence with phase averaging is similarly lost.",
        "positive": "Boundary States in Graphene Heterojunctions: A new type of states in graphene-based planar heterojunctions has been\nstudied in the envelope wave function approximation. The condition for the\nformation of these states is the intersection between the dispersion curves of\ngraphene and its gap modification. This type of states can also occur in smooth\ngraphene-based heterojunctions."
    },
    {
        "anchor": "Magneto-oscillations on specific heat of graphene monolayer: Measurement of magnetic oscillations on thermodynamic quantities (like\nmagnetization and specific heat), is one of the experimental methods to access\nthe density of states of electronic systems. In the present paper we therefore\ntheoretically explore the oscillatory phenomena on the specific heat of\ngraphenes considering gapped and gapless cases in a quantized magnetic field.\nFurther situations is also considered, as the influence of impurities, Coulomb\ninteraction and phonons. We could then map the magnetic oscillations on the\nspecific heat of graphenes under these constraints and the obtained results are\na good starting point and guide for further experimental works.",
        "positive": "High sensitivity microwave detection using a magnetic tunnel junction in\n  the absence of an external applied magnetic field: In the absence of any external applied magnetic field, we have found that a\nmagnetic tunnel junction (MTJ) can produce a significant output direct voltage\nunder microwave radiation at frequencies, which are far from the ferromagnetic\nresonance condition, and this voltage signal can be increase by at least an\norder of magnitude by applying a direct current bias. The enhancement of the\nmicrowave detection can be explained by the nonlinear resistance/conductance of\nthe MTJs. Our estimation suggests that optimized MTJs should achieve\nsensitivities for non-resonant broadband microwave detection of about 5,000\nmV/mW."
    },
    {
        "anchor": "Ultrafast electron-phonon scattering in antiferromagnetic Dirac\n  semimetals: Topological antiferromagnetic systems, which exhibit anisotropic band\nstructures combined with complex relativistic spin structures in momentum\nspace, have shown strong magnetoresistance effects driven by Dirac fermion\ncharacteristics. While these new antiferromagnets have been studied in\ntransport experiments, very little is known about their spin-dependent\nelectronic dynamics on ultrafast timescales and far-from-equilibrium behavior.\nThis paper investigates theoretically the spin-dependent electronic dynamics\ndue to electron-phonon scattering in a model electronic band structure that\ncorresponds to a Dirac semimetal antiferromagnet. Following a spin conserving\ninstantaneous excitation we obtain a change of the antiferromagnetic spin\npolarization due to the scattering dynamics for the site-resolved spin\nexpectation values. This allows us to identify fingerprints of the anisotropic\nband structure in the carrier dynamics on ultrashort timescales which should be\nobservable in present experimental set-ups.",
        "positive": "Efficient injection of spin-polarized excitons and optical spin\n  orientation of a single Mn2+ ion in a CdSe/ZnSe quantum dot: Circularly polarized optical excitation is used to demonstrate the efficient\ninjection of spin-polarized excitons to individual self-assembled CdSe quantum\ndots in ZnSe barrier. The exciton spin-transfer is studied by means of\npolarization-resolved single dot spectroscopy performed in magnetic field\napplied in Faraday configuration. Detailed analysis of the neutral exciton\nphotoluminescence spectra reveals the presence of exciton spin relaxation\nduring its lifetime in a quantum dot. This process is seen for both nonmagnetic\ndots and those containing single Mn$^{2+}$ ions. Taking this into account we\ndetermine the spin-polarization degree of excitons injected to a dot under\ncircularly polarized below-the-barrier optical excitation at 488 nm. It is\nfound to be close to 40% in the entire range of the applied magnetic field.\nExploiting the established spin-conserving excitation channel we demonstrate\nthe optical spin orientation of a single Mn$^{2+}$ ion embedded in a CdSe/ZnSe\nquantum dot."
    },
    {
        "anchor": "Dynamic current-current susceptibility in 3D Dirac and Weyl semimetals: We study the linear response of doped three dimensional Dirac and Weyl\nsemimetals to vector potentials, by calculating the wave-vector and frequency\ndependent current-current response function analytically. The longitudinal part\nof the dynamic current-current response function is then used to study the\nplasmon dispersion, and the optical conductivity. The transverse response in\nthe static limit yields the orbital magnetic susceptibility. In a Weyl\nsemimetal, along with the current-current response function, all these\nquantities are significantly impacted by the presence of parallel electric and\nmagnetic fields (a finite ${\\bf E}\\cdot{\\bf B}$ term), and can be used to\nexperimentally explore the chiral anomaly.",
        "positive": "Zero field spin polarization in a 2D paramagnetic resonant tunneling\n  diode: We study I-V characteristics of an all-II-VI semiconductor resonant tunneling\ndiode with dilute magnetic impurities in the quantum well layer. Bound magnetic\npolaron states form in the vicinity of potential fluctuations at the well\ninterface while tunneling electrons traverse these interface quantum dots. The\nresulting microscopic magnetic order lifts the degeneracy of the resonant\ntunneling states. Although there is no macroscopic magnetization, the resulting\nresonant tunneling current is highly spin polarized at zero magnetic field due\nto the zero field splitting. Detailed modeling demonstrates that the local spin\npolarization efficiency exceeds 90% without an external magnetic field."
    },
    {
        "anchor": "Spin-dependent coupling between quantum dots and topological quantum\n  wires: Considering Rashba quantum wires with a proximity-induced superconducting gap\nas physical realizations of Majorana fermions and quantum dots, we calculate\nthe overlap of the Majorana wave functions with the local wave functions on the\ndot. We determine the spin-dependent tunneling amplitudes between these two\nlocalized states and show that we can tune into a fully spin polarized\ntunneling regime by changing the distance between dot and Majorana fermion.\nUpon directly applying this to the tunneling model Hamiltonian, we calculate\nthe effective magnetic field on the quantum dot flanked by two Majorana\nfermions. The direction of the induced magnetic field on the dot depends on the\noccupation of the nonlocal fermion formed from the two Majorana end states\nwhich can be used as a readout for such a Majorana qubit.",
        "positive": "Polar Kerr Effect and Time Reversal Symmetry Breaking in Bilayer\n  Graphene: The unique sensitivity of optical response to different types of symmetry\nbreaking can be used to detect and identify spontaneously ordered many-body\nstates in bilayer graphene. We predict a strong response at optical\nfrequencies, sensitive to electronic phenomena at low energies, which arises\nbecause of nonzero inter-band matrix elements of the electric current operator.\nIn particular, the polar Kerr rotation and reflection anisotropy provide\nfingerprints of the quantum anomalous Hall state and the nematic state,\ncharacterized by spontaneously broken time reversal symmetry and lattice\nrotation symmetry, respectively. These optical signatures, which undergo a\nresonant enhancement in the near-infrared regime, lie well within reach of\nexisting experimental techniques."
    },
    {
        "anchor": "Optimal control of magnetization dynamics in ferromagnetic\n  heterostructures by spin--polarized currents: We study the switching-process of the magnetization in a\nferromagnetic-normal-metal multilayer system by a spin polarized electrical\ncurrent via the spin transfer torque. We use a spin drift-diffusion equation\n(SDDE) and the Landau-Lifshitz-Gilbert equation (LLGE) to capture the coupled\ndynamics of the spin density and the magnetization dynamic of the\nheterostructure. Deriving a fully analytic solution of the stationary SDDE we\nobtain an accurate, robust, and fast self-consistent model for the\nspin-distribution and spin transfer torque inside general ferromagnetic/normal\nmetal heterostructures. Using optimal control theory we explore the switching\nand back-switching process of the analyzer magnetization in a seven-layer\nsystem. Starting from a Gaussian, we identify a unified current pulse profile\nwhich accomplishes both processes within a specified switching time.",
        "positive": "Modeling Subsurface Charge Accumulation Images of a Quantum Hall Liquid: Subsurface Charge Accumulation imaging is a cryogenic scanning probe\ntechnique that has recently been used to spatially probe incompressible strips\nformed in a two-dimensional electron system (2DES) at high magnetic fields. In\nthis paper, we present detailed numerical modeling of these data. At a basic\nlevel, the method produces results that agree well with the predictions of\nmodels based on simple circuit elements. Moreover, the modeling method is\nsufficiently advanced to simulate the spatially resolved measurements. By\ncomparing directly the simulations to the experimentally measured data, we can\nextract quantitatively local electronic features of the 2DES. In particular, we\ndeduce the electron density of states inside the incompressible strips and\nelectrical resistance across them."
    },
    {
        "anchor": "Overcoming damping in spin wave propagation: A continuous excitation\n  approach to determine time-dependent dispersion diagrams in 2D magnonic\n  crystals: We propose an alternative micromagnetic approach to determine the spin wave\ndispersion relations in magnonic structures. Characteristic of the method is\nthat a limited area of the system is continuously excited with a spatially\nuniform oscillating field, tuned at a given frequency. After a transitory time,\nthe regime magnetization dynamics is collected and a spatial Fourier analysis\non it determines the frequency vs wave vector relation. Combining several\nsimulations in any predetermined range of frequencies, at any resolution, we\ninvestigate the dispersion relations for different kinds of magnonic crystals:\na dot array, an antidot array, and a bicomponent film. Especially compared to\ntraditional pulse-excitation methods this technique has many advantages. First,\nthe excitation power is concentrated at a single frequency, allowing the\ncorresponding spin waves to propagate with very low attenuation, resulting in a\nhigher k-space resolution. Second, the model allows to include very large wave\nvector components, necessary to describe the high-frequency response of\nnon-quantized spin waves in quasi-continuous systems. Finally, we address some\npossible experimental opportunities with respect to excitation/detection\ntechniques over large distances and the observation of the odd/even symmetry of\nspin waves using Brillouin light scattering.",
        "positive": "Non-linear dynamics of a driven nanomechanical single electron\n  transistor: We analyze the response of a nanomechanical resonator to an external drive\nwhen it is also coupled to a single-electron transistor (SET). The interaction\nbetween the SET electrons and the mechanical resonator depends on the amplitude\nof the mechanical motion leading to a strongly non-linear response to the drive\nwhich is similar to that of a Duffing oscillator. We show that the average\ndynamics of the resonator is well-described by a simple effective model which\nincorporates damping and frequency renormalization terms which are amplitude\ndependent. We also find that for a certain range of parameters the system\ndisplays interesting bistable dynamics in which noise arising from charge\nfluctuations causes the resonator to switch slowly between different dynamical\nstates."
    },
    {
        "anchor": "Type-II topological phase transitions of topological skyrmion phases: We present minimal toy models for topological skyrmion phases of matter,\nwhich generically realize type-II topological phase transitions in effectively\nnon-interacting systems, those which occur without closing of the minimum\ndirect bulk energy gap. We study the bulk-boundary correspondence in detail to\nshow that a non-trivial skyrmion number yields a rich bulk-boundary\ncorrespondence. We observe gapless edge states, which are robust against\ndisorder, due to non-trivial skyrmion number. Edge states corresponds to bands,\nwhich do not traverse the bulk gap, instead yielding gaplessness due to their\noverlap in energy and exponential localization on opposite edges of the system.\nThese gapless boundary modes can occur for total Chern number zero, and\nfurthermore correspond to rich real-space spin textures with strong\npolarization of spin along the real-space edge. By introducing toy models\ngenerically exhibiting type-II topological phase transitions and characterizing\nthe bulk-boundary correspondence due to non-trivial skyrmion number in these\nmodels, we lay the groundwork for understanding consequences of the quantum\nskyrmion Hall effect.",
        "positive": "Friedel oscillations at the Dirac-cone-merging point in anisotropic\n  graphene: We study the Friedel oscillations induced by a localized impurity in\nanisotropic graphene. We focus on the limit when the two inequivalent Dirac\npoints merge. We find that in this limit the Friedel oscillations manifest very\npeculiar features, such as a strong asymmetry and an atypical inverse\nsquare-root decay. Our calculations are performed using both a T-matrix\napproximation and a tight-binding exact diagonalization technique. They allow\nus to obtain numerically the local density of states as a function of energy\nand position, as well as an analytical form of the Friedel oscillations in the\ncontinuum limit. The two techniques yield results that are in excellent\nagreement, confirming the accuracy of such methods to approach this problem."
    },
    {
        "anchor": "Signatures of phonon and defect-assisted tunneling in planar\n  metal-hexagonal boron nitride-graphene junctions: Electron tunneling spectroscopy measurements on van der Waals\nheterostructures consisting of metal and graphene (or graphite) electrodes\nseparated by atomically thin hexagonal boron nitride tunnel barriers are\nreported. The tunneling conductance dI/dV at low voltages is relatively weak,\nwith a strong enhancement reproducibly observed to occur at around |V| ~ 50 mV.\nWhile the weak tunneling at low energies is attributed to the absence of\nsubstantial overlap, in momentum space, of the metal and graphene Fermi\nsurfaces, the enhancement at higher energies signals the onset of inelastic\nprocesses in which phonons in the heterostructure provide the momentum\nnecessary to link the Fermi surfaces. Pronounced peaks in the second derivative\nof the tunnel current, are observed at voltages where known phonon modes in the\ntunnel junction have a high density of states. In addition, features in the\ntunneling conductance attributed to single electron charging of nanometer-scale\ndefects in the boron nitride are also observed in these devices. The small\nelectronic density of states of graphene allows the charging spectra of these\ndefect states to be electrostatically tuned, leading to Coulomb diamonds in the\ntunneling conductance.",
        "positive": "Photon Antibunching in the Photoluminescence Spectra of a Single Carbon\n  Nanotube: We report the first observation of photon antibunching in the\nphotoluminescence from single carbon nanotubes. The emergence of a fast\nluminescence decay component under strong optical excitation indicates that\nAuger processes are partially responsible for inhibiting two-photon generation.\nAdditionally, the presence of exciton localization at low temperatures ensures\nthat nanotubes emit photons predominantly one by one. The fact that multiphoton\nemission probability can be smaller than 5% suggests that carbon nanotubes\ncould be used as a source of single photons for applications in quantum\ncryptography."
    },
    {
        "anchor": "Theory of superdiffusive spin transport in noncollinear magnetic\n  multilayers: Ultrafast demagnetization induced by femtosecond laser pulses in thin\nmetallic layers is caused by the outflow of spin-polarized hot electron\ncurrents describable by the superdiffusive transport model. These\nlaser-generated spin currents can cross the interface into another magnetic\nlayer and give rise to magnetization dynamics in magnetic spin valves with\nnoncollinear magnetizations. To describe ultrafast transport and spin dynamics\nin such nanostructures we develop here the superdiffusive theory for general\nnoncollinear magnetic multilayers. Specifically, we introduce an Al/Ni/Ru/Fe/Ru\nmultilayer system with noncollinear Ni and Fe magnetic moments and analyze how\nthe ultrafast demagnetization and spin-transfer torque depend on the\nnoncollinearity. We employ ab initio calculations to compute the spin- and\nenergy-dependent transmissions of hot electrons at the interfaces of the\nmultilayer. Taking into account multiple electron scattering at interfaces and\nspin mixing in the spacer layer we find that the laser-induced demagnetization\nof the Ni layer and magnetization change of the Fe layer strongly depend on the\nangle between their magnetizations. Similarly, the spin-transfer torques on the\nNi and Fe layers and the total spin momentum absorbed in the Ni and Fe layer\nare found to vary markedly with the amount of noncollinearity.\n  These results suggest that changing the amount of noncollinearity in magnetic\nmultilayers one can efficiently control the hot electron spin transport, which\nmay open a way toward achieving fast, laser-driven spintronic devices.",
        "positive": "Coherence and density dynamics of excitons in a single-layer MoS$_2$\n  reaching the homogeneous limit: We measure the coherent nonlinear response of excitons in a single-layer of\nmolybdenum disulphide embedded in hexagonal boron nitride, forming a\n$h$-BN/MoS$_2$/$h$-BN heterostructure. Using four-wave mixing microscopy and\nimaging, we correlate the exciton homogeneous and inhomogeneous broadenings. We\nfind that the exciton dynamics is governed by microscopic disorder on top of\nthe ideal crystal properties. Analyzing the exciton ultra-fast density dynamics\nusing amplitude and phase of the response, we investigate the relaxation\npathways of the resonantly driven exciton population. The surface protection\nvia encapsulation provides stable monolayer samples with low disorder, avoiding\nsurface contaminations and the resulting exciton broadening and modifications\nof the dynamics. We identify areas localized to a few microns where the optical\nresponse is totally dominated by homogeneous broadening. Across the sample of\ntens of micrometers, weak inhomogeneous broadening and strain effects are\nobserved, attributed to the remaining interaction with the $h$-BN and\nimperfections in the encapsulation process."
    },
    {
        "anchor": "Chiral anomaly of Weyl magnons in stacked honeycomb ferromagnets: Chiral anomaly of Weyl magnons (WMs), featured by nontrivial band crossings\nat paired Weyl nodes (WNs) of opposite chirality, is investigated. It is shown\nthat WMs can be realized in stacked honeycomb ferromagnets. Using the\nAharonov-Casher effect that is about the interaction between magnetic moments\nand electric fields, the magnon motion in honeycomb layers can be quantized\ninto magnonic Landau levels (MLLs). The zeroth MLL is chiral so that\nunidirectional WMs propagate in the perpendicular (to the layer) direction for\na given WN under a magnetic field gradient from one WN to the other and change\ntheir chiralities, resulting in the magnonic chiral anomaly (MCA). A net magnon\ncurrent carrying spin and heat through the zeroth MLL depends linearly on the\nmagnetic field gradient and the electric field gradient in the ballistic\ntransport.",
        "positive": "Topological response of the anomalous Hall effect in MnBi2Te4 due to\n  magnetic canting: Three-dimensional (3D) compensated MnBi2Te4 is antiferromagnetic, but\nundergoes a spin-flop transition at intermediate fields, resulting in a canted\nphase before saturation. In this work, we experimentally show that the\nanomalous Hall effect (AHE) in MnBi2Te4 originates from a topological response\nthat is sensitive to the perpendicular magnetic moment and to its canting\nangle. Synthesis by molecular beam epitaxy allows us to obtain a large-area\nquasi-3D 24-layer MnBi2Te4 with near-perfect compensation that hosts the phase\ndiagram observed in bulk which we utilize to probe the AHE. This AHE is seen to\nexhibit an antiferromagnetic response at low magnetic fields, and a clear\nevolution at intermediate fields through surface and bulk spin-flop transitions\ninto saturation. Throughout this evolution, the AHE is super-linear versus\nmagnetization rather than the expected linear relationship. We reveal that this\ndiscrepancy is related to the canting angle, consistent with the symmetry of\nthe crystal. Our findings suggests that novel topological responses may be\nfound in non-collinear ferromagnetic, and antiferromagnetic phases."
    },
    {
        "anchor": "Non-equilibrium transport through a model quantum dot: Hartree-Fock\n  approximation and beyond: The finite-temperature transport properties of the spinless interacting\nfermion model coupled to non-interacting leads are investigated. Employing the\nunrestricted time-dependent Hartree-Fock (HF) approximation, the transmission\nprobability and the non-linear $I$-$V$ characteristics are calculated, and\ncompared with available analytical results and with numerical data obtained\nfrom a Hubbard-Stratonovich decoupling of the interaction. In the weak\ninteraction regime, the HF approximation reproduces the gross features of the\nexact $I$-$V$ characteristics but fails to account for subtle properties like\nthe particular power law for the reflected current in the interacting resonant\nlevel model.",
        "positive": "Correlation between lasing and transport properties in a quantum\n  dot-resonator system: We study a double quantum dot system coherently coupled to an electromagnetic\nresonator. By suitably biasing the system, a population inversion can be\ncreated between the dot levels. The resulting lasing state exists within a\nnarrow resonance window, where the transport current correlates with the lasing\nstate. It allows probing the lasing state via a current measurement. Moreover,\nthe resulting narrow current peak opens perspective for applications of the\nsetup for high resolution measurements."
    },
    {
        "anchor": "Screening properties and plasmons of Hg(Cd)Te quantum wells: Under certain conditions, Hg(Cd)Te quantum wells (QWs) are known to realize a\ntime-reversal symmetric, two-dimensional topological insulator phase. Its\nlow-energy excitations are well-described by the phenomenological\nBernevig-Hughes-Zhang (BHZ) model that interpolates between Schr\\\"odinger and\nDirac fermion physics. We study the polarization function of this model in\nrandom phase approximation (RPA) in the intrinsic limit and at finite doping.\nWhile the polarization properties in RPA of Dirac and Schr\\\"odinger particles\nare two comprehensively studied problems, our analysis of the BHZ model bridges\nthe gap between these two limits, shedding light on systems with intermediate\nproperties. We gain insight into the screening properties of the system and on\nits characteristic plasma oscillations. Interestingly, we discover two\ndifferent kinds of plasmons that are related to the presence of intra- and\ninterband excitations. Observable signatures of these plasmons are carefully\nanalyzed in a variety of distinct parameter regimes, including the\nexperimentally relevant ones for Hg(Cd)Te QWs. We conclude that the discovered\nplasmons are observable by Raman or electron loss spectroscopy.",
        "positive": "Theory of magnetoelectric photocurrent generated by direct interband\n  transitions in semiconductor quantum well: A linearly polarized light normally incident on a semiconductor quantum well\nwith spin-orbit coupling may generate pure spin current via direct interband\noptical transition. An electric photocurrent can be extracted from the pure\nspin current when an in-plane magnetic field is applied, which has been\nrecently observed in the InGaAs/InAlAs quantum well [Dai et al., Phys. Rev.\nLett. 104, 246601 (2010)]. Here we present a theoretical study of this\nmagnetoelectric photocurrent effect associated with the interband transition.\nBy employing the density matrix formalism, we show that the photoexcited\ncarrier density has an anisotropic distribution in k space, strongly dependent\non the orientation of the electron wavevector and the polarization of the\nlight. This anisotropy provides an intuitive picture of the observed dependence\nof the photocurrent on the magnetic field and the polarization of the light. We\nalso show that the ratio of the pure spin photocurrent to the magnetoelectric\nphotocurrent is approximately equal to the ratio of the kinetic energy to the\nZeeman energy, which enables us to estimate the magnitude of the pure spin\nphotocurrent. The photocurrent density calculated with the help of an\nanisotropic Rashba model and the Kohn-Luttinger model can produce all three\nterms in the fitting formula for measured current, with comparable order of\nmagnitude, but discrepancies are still present and further investigation is\nneeded."
    },
    {
        "anchor": "Shape transition of unstrained flattest single-walled carbon nanotubes\n  under pressure: Single walled carbon nanotube's cross section can be flattened under\nhydrostatic pressure. One example is the cross section of a single walled\ncarbon nanotube successively deforms from the original round shape to oval\nshape, then to peanut-like shape. At the transition point of reversible\ndeformation between convex shape and concave shape, the side wall of nanotube\nis flattest. This flattest tube has many attractive properties. In the present\nwork, an approximate approach is developed to determine the equilibrium shape\nof this unstrained flattest tube and the curvature distribution of this tube.\nOur results are in good agreement with recent numerical results, and can be\napplied to the study of pressure controlled electric properties of single\nwalled carbon nanotubes. The present method can also be used to study other\ndeformed inorganic and organic tube-like structures.",
        "positive": "Magnetoplasmons of the tilted-anisotropic Dirac cone material\n  $\u03b1-$(BEDT-TTF)$_2$I$_3$: We study the collective modes of a low-energy continuum model of the\nquasi-two-dimensional electron liquid in a layer of the organic compound\n$\\alpha-$(BEDT-TTF)$_2$I$_3$ in a perpendicular magnetic field. As testified by\nzero magnetic field transport experiments and \\textit{ab initio} theory, this\nmaterial hosts both massless and massive low-energy carriers, the former being\ndescribed by tilted and anisotropic Dirac cones. The polarizability of these\ncones is anisotropic, and two sets of magnetoplasmon modes occur between any\ntwo cyclotron resonances. We show that the tilt of the cones causes a unique\nintervalley damping effect: the upper hybrid mode of one cone is damped by the\nparticle-hole continuum of the other cone in generic directions. We analyse how\nthe presence of massive carriers affects the response of the system, and\ndemonstrate how doping can tune $\\alpha-$(BEDT-TTF)$_2$I$_3$ between regimes of\nisotropic and anisotropic screening."
    },
    {
        "anchor": "Quantum Nondemolition Measurement of a Kicked Qubit: We propose a quantum nondemolition measurement using a kicked two-state\nsystem (qubit). By tuning the waiting time between kicks to be the qubit\noscillation period, the kicking apparatus performs a nondemolition measurement.\nWhile dephasing is unavoidable, the nondemolition measurement can (1) slow\nrelaxation of diagonal density matrix elements, (2) avoid detector back-action,\nand (3) allow for a large signal-to-noise ratio. Deviations from the ideal\nbehavior are studied by allowing for detuning of the waiting time, as well as\nfinite-time, noisy pulses. The scheme is illustrated with a double-dot qubit\nmeasured by a gate-pulsed quantum point contact.",
        "positive": "Conductance oscillation due to the geometrical resonance in FNS double\n  junctions: We theoretically analyzed the Andreev reflection in ferromagnetic\nmetal/nonmagnetic metal/superconductor double junctions with special attention\nto the electron interference effect in the nonmagnetic metal layer. We showed\nthat the conductance oscillates as a function of the bias voltage due to the\ngeometrical resonance. We found that the exchange field, and therefore the spin\npolarization of the ferromagnetic metal can be determined from the period of\nthe conductance oscillation, which is proportional to the square root of the\nexchange field."
    },
    {
        "anchor": "Electron energy level statistics in graphene quantum dots: Motivated by recent experimental observations of size quantization of\nelectron energy levels in graphene quantum dots \\cite{ponomarenko} we\ninvestigate the level statistics in the simplest tight-binding model for\ndifferent dot shapes by computer simulation. The results are in a reasonable\nagreement with the experiment which confirms qualitatively interpretation of\nobserved level statistics in terms of \"Dirac billiards\" without taking into\naccount many-body effects. It is shown that edge effects are in general\nsufficient to produce the observed level distribution and that even strong bulk\ndisorder does not change the results drastically.",
        "positive": "Polarization and third-order Hall effect in III-V semiconductor\n  heterojunctions: We study Berry connection polarizability (BCP) induced electric polarization\nand third-order Hall (TOH) effect in a two-dimensional electron/hole gas\n(2DEG/2DHG) with Rashba-Dresselhaus (RD) spin-orbit couplings in III-V\nsemiconductor heterostructures. The electric polarization decreases with the\nincrease of the Fermi energy and is responsive to the electric field\norientation in the presence of RD spin-orbit couplings for both systems. We\ndetermine the BCP-induced TOH conductivity ($\\chi_{\\perp}^{\\text{I}}$) along\nwith the TOH conductivity associated with the band velocity\n($\\chi_{\\perp}^{\\text{II}}$). We find that the presence of an infinitesimal\namount of Dresselhaus coupling in addition to the dominant Rashba coupling\nresults in finite TOH responses. These conductivities vanish when the field is\naligned with and/or orthogonal to the symmetry lines $k_x\\pm k_y=0$ in both\nsystems. For typical system parameters in a 2DEG with $k$-linear RD\ninteractions, the magnitude of $\\chi_{\\perp}^{\\text{I}}$ is smaller than that\nof $\\chi_{\\perp}^{\\text{II}}$. On the other hand, when both the SO couplings\nare comparable, $\\chi_{\\perp}^{\\text{I}}$ shows a notable increase in\nmagnitude, owing to the distinctive characteristics of BCP. The TOH\nconductivity of 2DEG remains unchanged when Rashba and Dresselhaus spin-orbit\ncouplings are exchanged. For 2DHG with $k$-cubic RD interactions,\n$\\chi_{\\perp}^{\\text{I},h}$ exhibits a larger magnitude compared to\n$\\chi_{\\perp}^{\\text{II},h}$. Unlike the electron case, the BCP induced\n$\\chi_{\\perp}^{\\text{I},h}$ alters under the exchange of spin-orbit coupling\nparameters, whereas $\\chi_{\\perp}^{\\text{II},h}$ remains the same."
    },
    {
        "anchor": "Role of hexagonal boron nitride in protecting ferromagnetic\n  nanostructures from oxidation: Ferromagnetic contacts are widely used to inject spin polarized currents into\nnon-magnetic materials such as semiconductors or 2-dimensional materials like\ngraphene. In these systems, oxidation of the ferromagnetic materials poses an\nintrinsic limitation on device performance. Here we investigate the role of\nex-situ transferred chemical vapour deposited hexagonal boron nitride (hBN) as\nan oxidation barrier for nanostructured cobalt and permalloy electrodes. The\nchemical state of the ferromagnets was investigated using X-ray photoemission\nelectron microscopy owing to its high sensitivity and lateral resolution. We\nhave compared the oxide thickness formed on ferromagnetic nanostructures\ncovered by hBN to uncovered reference structures. Our results show that hBN\nreduces the oxidation rate of ferromagnetic nanostructures suggesting that it\ncould be used as an ultra-thin protection layer in future spintronic devices.",
        "positive": "Calculated magneto-resistance due to domain walls : the role of impurity\n  scattering: The existing Levy-Zhang approach to constructing the contribution to the\nresistivity of a magnetic domain wall is explored. The model equations are\nintegrated analytically, giving a closed form expression for the resistivity\nwhen the current flows in the wall. The Boltzmann equation is solved\nanalytically and the ratio of the spin up and spin down resistivities is\ncalculated and its dependence on the strength of the Coulomb and exchange\nscattering potentials is elucidated."
    },
    {
        "anchor": "Adiabatic quantum pumping at the Josephson frequency: We analyze theoretically adiabatic quantum pumping through a normal conductor\nthat couples the normal regions of two superconductor/normal\nmetal/superconductor Josephson junctions. By using the phases of the\nsuperconducting order parameter in the superconducting contacts as pumping\nparameters, we demonstrate that a non zero pumped charge can flow through the\ndevice. The device exploits the evolution of the superconducting phases due to\nthe ac Josephson effect, and can therefore be operated at very high frequency,\nresulting in a pumped current as large as a few nanoAmperes. The experimental\nrelevance of our calculations is discussed.",
        "positive": "Copropagating edge states produced by the interaction between electrons\n  and chiral phonons in two-dimensional materials: Unlike the chirality of electrons, the intrinsic chirality of phonons has\nonly surfaced in recent years. Here we report on the effects of the interaction\nbetween electrons and chiral phonons in two-dimensional materials by using a\nnon-perturbative solution. We show that chiral phonons introduce inelastic\n\\textit{Umklapp} processes resulting in copropagating edge states which coexist\nwith a continuum. Transport simulations further reveal the robustness of the\nedge states. Our results hint on the possibility of having a metal embedded\nwith hybrid electron-phonon states of matter."
    },
    {
        "anchor": "Probing the plateau-insulator quantum phase transition in the quantum\n  Hall regime: We report quantum Hall experiments on the plateau-insulator transition in a\nlow mobility In_{.53} Ga_{.47} As/InP heterostructure. The data for the\nlongitudinal resistance \\rho_{xx} follow an exponential law and we extract a\ncritical exponent \\kappa= .55 \\pm .05 which is slightly different from the\nestablished value \\kappa = .42 \\pm .04 for the plateau transitions. Upon\ncorrection for inhomogeneity effects, which cause the critical conductance\n\\sigma_{xx}^* to depend marginally on temperature, our data indicate that the\nplateau-plateau and plateau- insulator transitions are in the same universality\nclass.",
        "positive": "Manipulation of the nuclear spin ensemble in a quantum dot with chirped\n  magnetic resonance pulses: The nuclear spins in nanostructured semiconductors play a central role in\nquantum applications. The nuclear spins represent a useful resource for\ngenerating local magnetic fields but nuclear spin noise represents a major\nsource of dephasing for spin qubits. Controlling the nuclear spins enhances the\nresource while suppressing the noise. NMR techniques are challenging: the group\nIII and V isotopes have large spins with widely different gyromagnetic ratios;\nin strained material there are large atom-dependent quadrupole shifts; and\nnanoscale NMR is hard to detect. We report NMR on 100,000 nuclear spins of a\nquantum dot using chirped radiofrequency pulses. Following polarization, we\ndemonstrate a reversal of the nuclear spin. We can flip the nuclear spin back\nand forth a hundred times.We demonstrate that chirped NMR is a powerful way of\ndetermining the chemical composition, the initial nuclear spin temperatures and\nquadrupole frequency distributions for all the main isotopes. The key\nobservation is a plateau in the NMR signal as a function of sweep rate: we\nachieve inversion at the first quantum transition for all isotopes\nsimultaneously. These experiments represent a generic technique for\nmanipulating nanoscale inhomogeneous nuclear spin ensembles and open the way to\nprobe the coherence of such mesoscopic systems."
    },
    {
        "anchor": "Highly Conducting pi-Conjugated Molecular Junctions Covalently Bonded to\n  Gold Electrodes: We measure electronic conductance through single conjugated molecules bonded\nto Au metal electrodes with direct Au-C covalent bonds using the scanning\ntunneling microscope based break-junction technique. We start with molecules\nterminated with trimethyltin end groups that cleave off in situ resulting in\nformation of a direct covalent sigma bond between the carbon backbone and the\ngold metal electrodes. The molecular carbon backbone used in this study consist\nof a conjugated pi-system that has one terminal methylene group on each end,\nwhich bonds to the electrodes, achieving large electronic coupling of the\nelectrodes to the pi-system. The junctions formed with the prototypical example\nof 1,4-dimethylenebenzene show a conductance approaching one conductance\nquantum (G0 = 2e2/h). Junctions formed with methylene terminated oligophenyls\nwith two to four phenyl units show a hundred-fold increase in conductance\ncompared with junctions formed with amine-linked oligophenyls. The conduction\nmechanism for these longer oligophenyls is tunneling as they exhibit an\nexponential dependence of conductance with oligomer length. In addition,\ndensity functional theory based calculations for the Au-xylylene-Au junction\nshow near-resonant transmission with a cross-over to tunneling for the longer\noligomers.",
        "positive": "Kondo effects in a C_60 single-molecule transistor: We have used the electromigration technique to fabricate a\n  $\\rm{C_{{60}}}$ single-molecule transistor (SMT). We present a full\nexperimental study as a function of temperature, down to 35 mK, and as a\nfunction of magnetic field up to 8 T in a SMT with odd number of electrons,\nwhere the usual spin-1/2 Kondo effect occurs, with good agreement with theory.\nIn the case of even number of electrons, a low temperature magneto-transport\nstudy is provided, which demonstrates a Zeeman splitting of the zero-bias\nanomaly at energies well below the Kondo scale."
    },
    {
        "anchor": "Classification of Exceptional Points and Non-Hermitian Topological\n  Semimetals: Exceptional points are universal level degeneracies induced by\nnon-Hermiticity. Whereas past decades witnessed their new physics, the unified\nunderstanding has yet to be obtained. Here we present the complete\nclassification of generic topologically stable exceptional points according to\ntwo types of complex-energy gaps and fundamental symmetries of charge\nconjugation, parity, and time reversal. This classification reveals unique\nnon-Hermitian gapless structures with no Hermitian analogs and systematically\npredicts unknown non-Hermitian semimetals and nodal superconductors; a\ntopological dumbbell of exceptional points in three dimensions is constructed\nas an illustration. Our work paves the way toward richer phenomena and\nfunctionalities of exceptional points and non-Hermitian topological semimetals.",
        "positive": "Comparative study of theoretical methods for nonequilibrium quantum\n  transport: We present a detailed comparison of three different methods designed to\ntackle nonequilibrium quantum transport, namely the functional renormalization\ngroup (fRG), the time-dependent density matrix renormalization group (tDMRG),\nand the iterative summation of real-time path integrals (ISPI). For the\nnonequilibrium single-impurity Anderson model (including a Zeeman term at the\nimpurity site), we demonstrate that the three methods are in quantitative\nagreement over a wide range of parameters at the particle-hole symmetric point\nas well as in the mixed-valence regime. We further compare these techniques\nwith two quantum Monte Carlo approaches and the time-dependent numerical\nrenormalization group method."
    },
    {
        "anchor": "The saddle-point exciton signature on high harmonic generation in 2D\n  hexagonal nanostructures: The disclosure of basic nonlinear optical properties of graphene-like\nnanostructures with correlated electron-hole nonlinear dynamics over a wide\nrange of frequencies and pump field intensities is of great importance for both\ngraphene fundamental physics and for expected novel applications of 2D\nhexagonal nanostructures in extreme nonlinear optics. In the current paper, the\nnonlinear interaction of 2D hexagonal nanostructures with the bichromatic\ninfrared driving field taking into account many-body Coulomb interaction is\ninvestigated. Numerical investigation in the scope of the Bloch equations\nwithin the Houston basis that take into account $e-e$ and $e-h$ interactions in\nthe Hartree-Fock approximation reveals significant excitonic effects in the\nhigh harmonic generation process in 2D hexagonal nanostructures such as\ngraphene and silicene. It is shown that due to the correlated electron-hole\nnonlinear dynamics around the van Hove singularity, spectral caustics in the\nhigh harmonic generation spectrum are induced near the saddle point excitonic\nresonances.",
        "positive": "Edge-Magnetoplasmon Wave-Packet Revivals in the Quantum Hall Effect: The quantum Hall effect is necessarily accompanied by low-energy excitations\nlocalized at the edge of a two-dimensional electron system. For the case of\nelectrons interacting via the long-range Coulomb interaction, these excitations\nare edge magnetoplasmons. We address the time evolution of localized\nedge-magnetoplasmon wave packets. On short times the wave packets move along\nthe edge with classical E cross B drift. We show that on longer times the wave\npackets can have properties similar to those of the Rydberg wave packets that\nare produced in atoms using short-pulsed lasers. In particular, we show that\nedge-magnetoplasmon wave packets can exhibit periodic revivals in which a\ndispersed wave packet reassembles into a localized one. We propose the study of\nedge-magnetoplasmon wave packets as a tool to investigate dynamical properties\nof integer and fractional quantum-Hall edges. Various scenarios are discussed\nfor preparing the initial wave packet and for detecting it at a later time. We\ncomment on the importance of magnetoplasmon-phonon coupling and on quantum and\nthermal fluctuations."
    },
    {
        "anchor": "High Surface Conductivity of Fermi Arc Electrons in Weyl semimetals: Weyl semimetals (WSMs), a new type of topological condensed matter, are\ncurrently attracting great interest due to their unusual electronic states and\nintriguing transport properties such as chiral anomaly induced negative\nmagnetoresistance, a semi--quantized anomalous Hall effect and the debated\nchiral magnetic effect. These systems are close cousins of topological\ninsulators (TIs) which are known for their disorder tolerant surface states.\nSimilarly, WSMs exhibit unique topologically protected Fermi arcs surface\nstates. Here we analyze electron--phonon scattering, a primary source of\nresistivity in metals at finite temperatures, as a function of the shape of the\nFermi arc where we find that the impact on surface transport is significantly\ndependent on the arc curvature and disappears in the limit of a straight arc.\nNext, we discuss the effect of strong surface disorder on the resistivity by\nnumerically simulating a tight binding model with the presence of quenched\nsurface vacancies using the Coherent Potential Approximation (CPA) and\nKubo--Greenwood formalism. We find that the limit of a straight arc geometry is\nremarkably disorder tolerant, producing surface conductivity that is a factor\nof 50 larger of a comparable set up with surface states of TI. Finally, a\nsimulation of the effects of surface vacancies on TaAs is presented,\nillustrating the disorder tolerance of the topological surface states in a\nrecently discovered WSM material.",
        "positive": "Spin dynamics in semiconductors in the streaming regime: We present results of a cross-disciplinary theoretical research at the\ninterface of spin physics and hot-electron transport. A moderately strong\nelectric field is assumed to provide the streaming regime where each free\ncharge carrier, an electron or a hole, accelerates quasiballistically in the\n\"passive\" region until reaching the optical-phonon energy, then emits an\noptical phonon and starts the next period of acceleration. The inclusion of\nspin degree of freedom into the streaming-regime kinetics gives rise to rich\nand interesting spin-related phenomena. Firstly, in the streaming regime the\nspin relaxation is substantially modified, and the current-induced spin\norientation is remarkably increased. Under short-pulsed photoexcitation at the\nbottom of conduction band the photoelectrons execute a periodic damped motion\nin the energy space with the period equal to the free flight time of an\nelectron in the passive region. If the short optical pulse is circularly\npolarized so that the photocarriers are spin oriented, then the spin energy\ndistribution is oscillating in time as well, which can be detected in the\npump-probe time-resolved experiments. We show that the spin-orbit splitting of\nthe conduction band becomes a source for additional spin oscillations, periodic\nor aperiodic depending on the value of electric field."
    },
    {
        "anchor": "Insertable system for fast turnaround time microwave experiments in a\n  dilution refrigerator: Microwave experiments in dilution refrigerators are a central tool in the\nfield of superconducting quantum circuits and other research areas. This type\nof experiments relied so far on attaching a device to the mixing chamber of a\ndilution refrigerator. The minimum turnaround time in this case is a few days\nas required by cooling down and warming up the entire refrigerator. We\ndeveloped a new approach, in which a suitable sample holder is attached to a\ncold-insertable probe and brought in contact with transmission lines\npermanently mounted inside the cryostat. The total turnaround time is 8 hours\nif the target temperature is 80 mK. The lowest attainable temperature is 30 mK.\nOur system can accommodate up to six transmission lines, with a measurement\nbandwidth tested between DC and 12 GHz. This bandwidth is limited by low pass\ncomponents in the setup; we expect the intrinsic bandwidth to be at least 18\nGHz. We present our setup, discuss the experimental procedure, and give\nexamples of experiments enabled by this system. This new measurement method\nwill have a major impact on systematic ultra-low temperature studies using\nmicrowave signals, including those requiring quantum coherence.",
        "positive": "Dipole coupling of a bilayer graphene quantum dot to a high-impedance\n  microwave resonator: We implement circuit quantum electrodynamics (cQED) with quantum dots in\nbilayer graphene, a maturing material platform for semiconductor qubits that\ncan host long-lived spin and valley states. The presented device combines a\nhigh-impedance ($Z_\\mathrm{r} \\approx 1 \\mathrm{k{\\Omega}}$) superconducting\nmicrowave resonator with a double quantum dot electrostatically defined in a\ngraphene-based van der Waals heterostructure. Electric dipole coupling between\nthe subsystems allows the resonator to sense the electric susceptibility of the\ndouble quantum dot from which we reconstruct its charge stability diagram. We\nachieve sensitive and fast detection with a signal-to-noise ratio of 3.5 within\n1 ${\\mu}\\mathrm{s}$ integration time. The charge-photon interaction is\nquantified in the dispersive and resonant regimes by comparing the\ncoupling-induced change in the resonator response to input-output theory,\nyielding a maximal coupling strength of $g/2{\\pi} = 49.7 \\mathrm{MHz}$. Our\nresults introduce cQED as a probe for quantum dots in van der Waals materials\nand indicate a path toward coherent charge-photon coupling with bilayer\ngraphene quantum dots."
    },
    {
        "anchor": "BCS-BEC crossover in a strongly correlated Fermi gas: We study the BCS-BEC crossover in the strongly correlated regime of an\nultra-cold rotating two component Fermi gas. Strong correlations are shown to\ngenerate an additional long-range interaction which results in a modified\ncrossover region compared to the non-rotating situation. The two-particle\ncorrelation function reveals a smooth crossover between the s-wave paired\nfermionic fractional quantum Hall state and the bosonic Laughlin state.",
        "positive": "Probing Intrinsic Material Conductivity in Two-Terminal Devices: A\n  Resistance-Difference Method: It is generally impossible to separately measure the resistance of the\nfunctional component (i.e., the intrinsic device materials) and the parasitic\ncomponent (i.e., terminals, interfaces and serial loads) in a two-terminal\ndevice. Yet such knowledge is important for understanding device physics and\ndesigning device systems. Here, we consider a case where an electric current,\ntemperature, or magnetic field causes a small but identical relative\nconductivity change of the device materials. We find an exact solution to this\nrelative change by a simple resistance-data analysis of similarly configured\ntwo-terminal devices. The solution is obtainable even if the change is quite\nsmall, say, less than 0.1%. In special cases of small relative changes in\nparasitic resistance, the absolute parasitic resistance is also obtainable. Our\nmethod is especially useful for studying the switching and transport\ncharacteristics of the emergent non-volatile resistance memory."
    },
    {
        "anchor": "Excitation spectroscopy of single quantum dots at tunable positive,\n  neutral and negative charge states: We present a comprehensive study of the optical transitions and selection\nrules of variably charged single self-assembled InAs/GaAs quantum dots. We\napply high resolution polarization sensitive photoluminescence excitation\nspectroscopy to the same quantum dot for three different charge states: neutral\nand negatively or positively charged by one additional electron or hole. From\nthe detailed analysis of the excitation spectra, a full understanding of the\nsingle-carrier energy levels and the interactions between carriers in these\nlevels is extracted for the first time.",
        "positive": "Photoluminescence spectrum of an interacting two-dimensional electron\n  gas at \u03bd=1: We report on the theoretical photoluminescence spectrum of the interacting\ntwo-dimensional electron gas at filling factor one (\\nu=1). We considered a\nmodel similar to the one adopted to study the X-ray spectra of metals and\nsolved it analytically using the bosonization method previously developed for\nthe two-dimensional electron gas at \\nu=1. We calculated the emission spectra\nof the right and the left circularly polarized radiations for the situations\nwhere the distance between the two-dimensional electron gas and the valence\nband hole are smaller and greater than the magnetic length. For the former, we\nshowed that the polarized photoluminescence spectra can be understood as the\nrecombination of the so-called excitonic state with the valence band hole\nwhereas, for the latter, the observed emission spectra can be related to the\nrecombination of a state formed by a spin down electron bound to n spin waves.\nThis state seems to be a good description for the quantum Hall skyrmion."
    },
    {
        "anchor": "An Ising-Glauber Spin Cluster Model for Temperature Dependent\n  Magnetization Noise in SQUIDs: Clusters of interacting two-level-systems (TLS),likely due to $F^+$ centers\nat the metal-insulator interface, are shown to self consistently lead to\n$1/f^{\\alpha }$ magnetization noise in SQUIDs. By introducing a\ncorrelation-function calculation method and without any a priori assumptions on\nthe distribution of fluctuation rates, it is shown why the flux noise is only\nweakly temperature dependent with $\\alpha\\lesssim 1$, while the inductance\nnoise has a huge temperature dependence seen in experiment, even though the\nmechanism producing both spectra is the same. Though both ferromagnetic- RKKY\nand short-range-interactions (SRI) lead to strong flux-inductance-noise\ncross-correlations seen in experiment, the flux noise varies a lot with\ntemperature for SRI. Hence it is unlikely that the TLS's time reversal symmetry\nis broken by the same mechanism which mediates surface ferromagnetism in\nnanoparticles and thin films of the same insulator materials.",
        "positive": "Electrical control of a long-lived spin qubit in a Si/SiGe quantum dot: Nanofabricated quantum bits permit large-scale integration but usually suffer\nfrom short coherence times due to interactions with their solid-state\nenvironment. The outstanding challenge is to engineer the environment so that\nit minimally affects the qubit, but still allows qubit control and scalability.\nHere we demonstrate a long-lived single-electron spin qubit in a Si/SiGe\nquantum dot with all-electrical two-axis control. The spin is driven by\nresonant microwave electric fields in a transverse magnetic field gradient from\na local micromagnet, and the spin state is read out in single-shot mode.\nElectron spin resonance occurs at two closely spaced frequencies, which we\nattribute to two valley states. Thanks to the weak hyperfine coupling in\nsilicon, Ramsey and Hahn echo decay timescales of 1us and 40us, respectively,\nare observed. This is almost two orders of magnitude longer than the intrinsic\ntimescales in III-V quantum dots, while gate operation times are comparable to\nthose achieved in GaAs. This places the single-qubit rotations in the\nfault-tolerant regime and strongly raises the prospects of quantum information\nprocessing based on quantum dots."
    },
    {
        "anchor": "Spin and valley polarization of plasmons in silicene due to external\n  fields: The electronic properties of the novel two dimensional (2D) material silicene\nare strongly influenced by the application of a perpendicular electric field\n$E_z$ and of an exchange field $M$ due to adatoms positioned on the surface or\na ferromagnetic substrate. Within the random phase approximation, we\ninvestigate how electron-electron interactions are affected by these fields and\npresent analytical and numerical results for the dispersion of plasmons, their\nlifetime, and their oscillator strength. We find that the combination of the\nfields $E_z$ and $M$ brings a spin and valley texture to the particle-hole\nexcitation spectrum and allows the formation of spin- and valley-polarized\nplasmons. When the Fermi level lies in the gap of one spin in one valley, the\nintraband region of the corresponding spectrum disappears. For zero $E_z$ and\nfinite $M$ the spin symmetry is broken and spin polarization is possible. The\nlifetime and oscillator strength of the plasmons are shown to depend strongly\non the number of spin and valley type electrons that form the electron-hole\npairs.",
        "positive": "Low-temperature ballistic transport in nanoscale epitaxial graphene\n  cross junctions: We report on the observation of inertial-ballistic transport in nanoscale\ncross junctions fabricated from epitaxial graphene grown on SiC(0001).\nBallistic transport is indicated by a negative bend resistance of R12,43 ~ 170\nohm which is measured in a non-local, four-terminal configuration at 4.2 K and\nwhich vanishes as the temperature is increased above 80 K."
    },
    {
        "anchor": "Magnetotransport properties of a twisted bilayer graphene in the\n  presence of external electric and magnetic field: We extensively investigate the electronic and transport properties of a\ntwisted bilayer graphene when subjected to both an external perpendicular\nelectric field and a magnetic field. Using a basic tight-binding model, we show\nthe flat electronic band properties as well as the density of states (DOS),\nboth without and with the applied electric field. In the presence of an\nelectric field, the degeneracy at the Dirac points is lifted where the\nnon-monotonic behavior of the energy gap exists, especially for twist angles\nbelow 3$^\\circ$. We also study the behavior of the Landau levels (LL) spectra\nfor different twist angles within a very low energy range. These LL spectra get\nmodified under the influence of the external electric field. Moreover, we\ncalculate the dc Hall conductivity ($\\sigma_{xy}$) for a very large system\nusing the Kernel Polynomial Method (KPM). Interestingly, $\\sigma_{xy}$ makes a\ntransition from a half-integer to an integer quantum Hall effect, \\textit{i.e.}\nthe value of $\\sigma_{xy}$ shifts from $\\pm 4(n+1/2) (2e^2/h)$ ($n$ is an\ninteger) to $\\pm 2n (2e^2/h)$ around a small twist angle of\n$\\theta=2.005^\\circ$. At this angle, $\\sigma_{xy}$ acquires a Hall plateau at\nzero Fermi energy. However, the behavior of $\\sigma_{xy}$ remains unaltered\nwhen the system is exposed to the electric field, particularly at the magic\nangle where the bands in both layers can hybridize and strong interlayer\ncoupling plays a crucial role.",
        "positive": "Coupling of bonding and antibonding electron orbitals in double quantum\n  dots by spin-orbit interaction: We perform a systematic exact diagonalization study of spin-orbit coupling\neffects for stationary few-electron states confined in quasi two-dimensional\ndouble quantum dots. We describe the spin-orbit-interaction induced coupling\nbetween bonding and antibonding orbitals and its consequences for\nmagneto-optical absorption spectrum. The spin-orbit coupling for odd electron\nnumbers (one, three) %only weakly perturbs the ground-state wave functions.\n%Nevertheless, %the spin-orbit interaction opens avoided crossings between low\nenergy excited levels of opposite spin orientation and opposite spatial parity.\nFor two-electrons the spin-orbit coupling allows for low-energy optical\ntransitions that are otherwise forbidden by spin and parity selection rules. We\ndemonstrate that the energies of optical transitions can be significantly\nincreased by an in-plane electric field but only for odd electron numbers.\nOccupation of single-electron orbitals and effects of spin-orbit coupling on\nelectron distribution between the dots are also discussed."
    },
    {
        "anchor": "Accessing long timescales in the relaxation dynamics of spins coupled to\n  a conduction-electron system using absorbing boundary conditions: The relaxation time of a classical spin interacting with a large\nconduction-electron system is computed for a weak magnetic field, which\ninitially drives the spin out of equilibrium. We trace the spin and the\nconduction-electron dynamics on a time scale, which exceeds the characteristic\nelectronic scale that is set by the inverse nearest-neighbor hopping by more\nthan five orders of magnitude. This is achieved with a novel construction of\nabsorbing boundary conditions, which employs a generalized Lindblad\nmaster-equation approach to couple the edge sites of the conduction-electron\ntight-binding model to an external bath. The failure of the standard Lindblad\napproach to absorbing boundaries is traced back to artificial excitations\ninitially generated due to the coupling to the bath. This can be cured by\nintroducing Lindblad parameter matrices and by fixing those matrices to\nperfectly suppress initial-state artifacts as well as reflections of physical\nexcitations propagating to the system boundaries. Numerical results are\npresented and discussed for generic one-dimensional models of the electronic\nstructure.",
        "positive": "Scanning tunneling microscopy study of the possible topological surface\n  states in BiTeCl: Recently, the non-centrosymmetric bismuth tellurohalides such as BiTeCl are\nbeing studied as possible candidates of topological insulators. While some\nphotoemission studies showed that BiTeCl is an inversion asymmetric topological\ninsulator, others showed that it is a normal semiconductor with Rashba\nsplitting. Meanwhile, first-principle calculationsfailed to confirm the\nexistence of topological surface states in BiTeCl so far. Therefore, the\ntopological nature of BiTeCl requires further investigation. Here we report low\ntemperature scanning tunneling microscopy study on the surface states of BiTeCl\nsingle crystals. On the tellurium-terminated surfaces with low defect density,\nstrong evidences for topological surface states are found in the quasi-particle\ninterference patterns generated by the scattering of these states, both in the\nanisotropy of the scattering vectors and the fast decay of the interference\nnear step edges. Meanwhile, on samples with much higher defect densities, we\nobserved surface states that behave differently. Our results help to resolve\nthe current controversy on the topological nature of BiTeCl."
    },
    {
        "anchor": "Quantum field theoretical study of an effective spin model in coupled\n  optical cavity arrays: Atoms trapped in microcavities and interacting through the exchange of\nvirtual photons can model an anisotropic Heisenberg spin-1/2 lattice.\n  We do the quantum field theoretical study of such a system using the Abelian\nbosonization method followed by the renormalization group analysis. We present\ninteresting physics due to the presence of exchange anisotropy. An infinite\norder Kosterliz-Thouless-Berezinskii transition is replaced by second order XY\ntransition even an infinitesimal a small anisotropy in exchange coupling is\nintroduced. We predict a quantum phase transition between Mott insulating and\nphotonic superfluid phase due to detuning between the cavity and laser\nfrequency, a large detuning favours the photonic superfluid phase. We also do\nthe analysis of Jaynes and Cumming Hamiltonian to support results of quantum\nfield theoretical study.",
        "positive": "Critique of optical transition theories based on projection and\n  population criteria: Some many-body theories of optical transitions in solids were examined from\nprojection and population criteria. The results showed that state-independent\nprojection methods cannot be applied to electron systems with non-uniform\nenergy spectra. Moreover, neglecting some important terms in a second-order\napproximation leads to invalidation of the population criterion. In addition, a\nvalid theory satisfying these two criteria can be obtained using a proper\nstate-dependent projection operator and Kang-Choi reduction identity, and the\nresult can be interpreted using a diagram, which can model the quantum dynamics\nof electron in solids."
    },
    {
        "anchor": "Orbital magnetization and its effect in antiferromagnets on the\n  distorted fcc lattice: We study the intrinsic orbital magnetization (OM) in antiferromagnets on the\ndistorted face-centered-cubic lattice. The combined lattice distortion and spin\nfrustration induce nontrivial $k$-space Chern invariant, which turns to result\nin profound effects on the OM properties. We derive a specific relation between\nthe OM and the Hall conductivity, according to which it is found that the\nintrinsic OM vanishes when the electron chemical potential lies in the Mott\ngap. The distinct behavior of the intrinsic OM in the metallic and insulating\nregions is shown. The Berry phase effects on the thermoelectric transport is\nalso discussed.",
        "positive": "Formation of quantum dots in the potential fluctuations of InGaAs\n  heterostructures probed by scanning gate microscopy: The disordered potential landscape in an InGaAs/InAlAs two-dimensional\nelectron gas patterned into narrow wires is investigated by means of scanning\ngate microscopy. It is found that scanning a negatively charged tip above\nparticular sites of the wires produces conductance oscillations that are\nperiodic in the tip voltage. These oscillations take the shape of concentric\ncircles whose number and diameter increase for more negative tip voltages until\nfull depletion occurs in the probed region. These observations cannot be\nexplained by charging events in material traps, but are consistent with Coulomb\nblockade in quantum dots forming when the potential fluctuations are raised\nlocally at the Fermi level by the gating action of the tip. This interpretation\nis supported by simple electrostatic simulations in the case of a disorder\npotential induced by ionized dopants. This work represents a local\ninvestigation of the mechanisms responsible for the disorder-induced\nmetal-to-insulator transition observed in macroscopic two-dimensional electron\nsystems at low enough density."
    },
    {
        "anchor": "Entanglement polarization for the topological quadrupole phase: We propose the entanglement dipole polarization to describe the topological\nquadrupole phase. The quadrupole moment can be regarded as a pair of the dipole\nmoment, in which the total dipole moment is canceled. The entanglement\npolarization, we propose, is useful to detect such a constituent dipole\npolarization. We first introduce partitions of sites in the unit cell and\ndivide the system into two subsystems. Then, introducing an entanglement\nHamiltonian by tracing out one of the subsystems partly, we compute the dipole\npolarization of the occupied states associated with the entanglement\nHamiltonian, which is referred to as the entanglement polarization. Although\nthe total dipole polarization is vanishing, those of the subsystems can be\nfinite. The entanglement dipole polarization is quantized by reflection\nsymmetries. We also introduce the entanglement polarization of the edge states,\nwhich reveals that the edge states themselves are gapped and topologically\nnontrivial. Therefore, such edge states yield the zero energy edge states if\nthe system has boundaries. This is the origin of the corner states.",
        "positive": "Isotropic charge screening of the anisotropic black phosphorus revealed\n  by potassium adatoms: Black phosphorus has attracted great research interest due to its numerous\napplications in electronic devices, optoelectronic devices, energy storages and\nso on. Compared with the majority of two-dimensional materials, black\nphosphorus possesses a unique property, i.e. the strong in-plane anisotropy.\nAll the properties reported so far, including its effective mass, electron\nmobility, light absorption, thermal conductivity and so on, have shown great\nanisotropy in the basal plane. This property renders black phosphorus unique\napplications not achievable with other two-dimensional materials. In this work,\nhowever, we discover a remarkable isotropic behavior in the strongly\nanisotropic black phosphorus, i.e. its electrostatic screening of point\ncharges. We use the tip-induced band bending of a scanning tunneling microscope\nto map out the Coulomb field of ionized potassium adatoms on black phosphorus,\nand reveal its isotropic charge screening. This discovery is important for\nunderstanding electron scattering and transport in black phosphorus."
    },
    {
        "anchor": "Evanescent field optical readout of graphene mechanical motion at room\n  temperature: Graphene mechanical resonators have recently attracted considerable attention\nfor use in precision force and mass sensing applications. To date, readout of\ntheir oscillatory motion has typically required cryogenic conditions to achieve\nhigh sensitivity, restricting their range of applications. Here we report the\nfirst demonstration of evanescent optical readout of graphene motion, using a\nscheme which does not require cryogenic conditions and exhibits enhanced\nsensitivity and bandwidth at room temperature. We utilise a high $Q$\nmicrosphere to enable evanescent readout of a 70 $\\mu$m diameter graphene drum\nresonator with a signal-to-noise ratio of greater than 25 dB, corresponding to\na transduction sensitivity of $S_{N}^{1/2} = $ 2.6 $\\times 10^{-13}$ m\n$\\mathrm{Hz}^{-1/2}$. The sensitivity of force measurements using this\nresonator is limited by the thermal noise driving the resonator, corresponding\nto a force sensitivity of $F_{min} = 1.5 \\times 10^{-16}$ N\n${\\mathrm{Hz}}^{-1/2}$ with a bandwidth of 35 kHz at room temperature (T = 300\nK). Measurements on a 30 $\\mu$m graphene drum had sufficient sensitivity to\nresolve the lowest three thermally driven mechanical resonances.",
        "positive": "Current cross-correlations in a quantum Hall collider at filling factor\n  two: We use the non-equilibrium bosonization technique to study the effects of\nCoulomb interactions in mesoscopic electron colliders based on quantum Hall\n(QH) edge states at filing factor $\\nu = 2$. The current cross-correlations and\nFano factor, which carry the information about the exclusion statistics, are\ncalculated. It is shown that both these quantities have a non-analytical\ndependence on the source transparency, which scales as $\\log(1/T_s)$ at small\n$T_s \\ll 1$. This is the consequence of electron-electron interactions in the\noutgoing non-equilibrium states of the collider."
    },
    {
        "anchor": "Phonon Mediated Off-Resonant Quantum Dot-Cavity Coupling: A theoretical model for the phonon-mediated off-resonant coupling between a\nquantum dot and a cavity, under resonant excitation of the quantum dot, is\npresented. We show that the coupling is caused by electron-phonon interaction\nin the quantum dot and is enhanced by the cavity. We analyze recently observed\nresonant quantum dot spectroscopic data by our theoretical model.",
        "positive": "Magnetic field dependence of the electron spin revival amplitude in\n  periodically pulsed quantum dots: Periodic laser pulsing of singly charged semiconductor quantum dots in an\nexternal magnetic field leads to a synchronization of the spin dynamics with\nthe optical excitation. The pumped electron spins partially rephase prior to\neach laser pulse, causing a revival of electron spin polarization with its\nmaximum at the incidence time of a laser pulse. The amplitude of this revival\nis amplified by the frequency focusing of the surrounding nuclear spins. Two\ncomplementary theoretical approaches for simulating up to 20 million laser\npulses are developed and employed that are able to bridge between 11 orders of\nmagnitude in time: a fully quantum mechanical description limited to small\nnuclear bath sizes and a technique based on the classical equations of motion\napplicable for a large number of nuclear spins. We present experimental data of\nthe nonmonotonic revival amplitude as function of the magnetic field applied\nperpendicular to the optical axis. The dependence of the revival amplitude on\nthe external field with a profound minimum at $4\\;$T is reproduced by both of\nour theoretical approaches and is ascribed to the nuclear Zeeman effect. Since\nthe nuclear Larmor precession determines the electronic resonance condition, it\nalso defines the number of electron spin revolutions between pump pulses, the\norientation of the electron spin at the incidence time of a pump pulse, and the\nresulting revival amplitude. The magnetic field of $4\\;$T, for example,\ncorresponds to half a revolution of nuclear spins between two laser pulses."
    },
    {
        "anchor": "Inhomogeneous Josephson junction chains for superinductance optimization: We report a theoretical study of the low-frequency impedance of a Josephson\njunction chain whose parameters vary in space. Our goal is to find the optimal\nspatial profile which maximizes the total inductance of the chain without\nshrinking the low-frequency window where the chain behaves as an inductor. If\nthe spatial modulation is introduced by varying the junction areas, we find\nthat the best result is obtained for a spatially homogeneous chain, reported\nearlier in the literature. An improvement over the homogeneous result can be\nobtained by representing the junctions by SQUIDs with different loop areas, so\nthe inductances can be varied by applying a magnetic field. Still, we find that\nthis improvement becomes less important for longer chains.",
        "positive": "Penetration depth of low-coherence enhanced backscattered light in\n  sub-diffusion regime: The mechanisms of photon propagation in random media in the diffusive\nmultiple scattering regime have been previously studied using diffusion\napproximation. However, similar understanding in the low-order (sub-diffusion)\nscattering regime is not complete due to difficulties in tracking photons that\nundergo very few scatterings events. Recent developments in low-coherence\nenhanced backscattering (LEBS) overcome these difficulties and enable probing\nphotons that travel very short distances and undergo only a few scattering\nevents. In LEBS, enhanced backscattering is observed under illumination with\nspatial coherence length L_sc less than the scattering mean free path l_s. In\norder to understand the mechanisms of photon propagation in LEBS in the\nsubdiffusion regime, it is imperative to develop analytical and numerical\nmodels that describe the statistical properties of photon trajectories. Here we\nderive the probability distribution of penetration depth of LEBS photons and\nreport Monte Carlo numerical simulations to support our analytical results. Our\nresults demonstrate that, surprisingly, the transport of photons that undergo\nlow-order scattering events has only weak dependence on the optical properties\nof the medium (l_s and anisotropy factor g) and strong dependence on the\nspatial coherence length of illumination, L_sc, relative to those in the\ndiffusion regime. More importantly, these low order scattering photons\ntypically penetrate less than l_s into the medium due to low spatial coherence\nlength of illumination and their penetration depth is proportional to the\none-third power of the coherence volume (i.e. [l_s \\pi L_sc^2 ]^1/3)."
    },
    {
        "anchor": "Thermally and field-driven mobility of emergent magnetic charges in\n  square artificial spin ice: Designing and constructing model systems that embody the statistical\nmechanics of frustration is now possible using nanotechnology. We have arranged\nnanomagnets on a two-dimensional square lattice to form an artificial spin ice,\nand studied its fractional excitations, emergent magnetic monopoles, and how\nthey respond to a driving field using X-ray magnetic microscopy. We observe a\nregime in which the monopole drift velocity is linear in field above a critical\nfield for the onset of motion. The temperature dependence of the critical field\ncan be described by introducing an interaction term into the Bean-Livingston\nmodel of field-assisted barrier hopping. By analogy with electrical charge\ndrift motion, we define and measure a monopole mobility that is larger both for\nhigher temperatures and stronger interactions between nanomagnets. The mobility\nin this linear regime is described by a creep model of zero-dimensional charges\nmoving within a network of quasi-one-dimensional objects.",
        "positive": "Realistic Floquet semimetal with exotic topological linkages between\n  arbitrarily many nodal loops: Valence and conduction bands in nodal loop semimetals (NLSMs) touch along\nclosed loops in momentum space. If such loops can proliferate and link\nintricately, NLSMs become exotic topological phases with unconventional\ntopological characteristics and potentially peculiar transport properties. In\nconventional quantum materials or cold atom systems alike, such exotic phases\nnecessarily require non-local hopping and are therefore intrinsically\nunrealistic. In this work, we show how this hurdle can be surmounted through an\nexperimentally feasible periodic driving scheme. In particular, by tuning the\nperiod of a two-step periodic driving or some experimentally accessible\nparameters, we show how to generate arbitrarily many nodal loops that are\nlinked with various levels of complexity. Furthermore, we propose to use both\nthe Berry phase winding and the Alexander polynomial topological invariant to\ncharacterize the fascinating linkages among the nodal loops. This work thus\npresents a class of exotic Floquet topological phase that has hitherto not been\nproposed in any realistic setup."
    },
    {
        "anchor": "Graphene thermal break-down induced by anharmonic bending mode: The abrupt loss of mechanical stability of two-dimensional graphene-type\ncrystals at a certain transition temperature is described. At this temperature,\nthe graphene state with practically zero-speed bending sound and developed\nbending fluctuations becomes energetically favorable. Such phenomenon, akin to\nmelting, is naturally caused by the anharmonicity of crystal oscillations. In\norder to circumvent the known difficulties associated with taking into account\nthe anharmonic effects, we propose an original pseudo-harmonic approximation,\nwithin which we determine the free energy of the anharmonic crystal and find a\nnumerical characteristic for the intensity of bending vibrations at transition\ntemperature. This characteristic is similar to the empiric Lindemann criterion\nfor the melting phenomenon. At the same time, in contrast to the conventional\nLindemann criterion, the found characteristic is explicitly expressed through\nthe graphene bending moduli of the second, third, and fourth orders.",
        "positive": "Photo-Seebeck effect in single-crystalline bismuth telluride topological\n  insulator: Bismuth telluride is a low energy bulk band-gap topological system with\nconducting surface states. Besides its very good thermoelectric properties, it\nalso makes a very good candidate for broadband photodetectors. Here, we report\ntemperature-dependent photo-Seebeck effect in a bulk single crystalline bismuth\ntelluride. On light illumination, an electrically biased sample shows\ndistinguishable contributions in the measured current due to both the Seebeck\neffect and the normal photo-generated carriers within a narrow layer of the\nsample. Detailed experiments are performed to elucidate the distinction between\nthe Seebeck contribution and the photogenerated current. The\ntemperature-dependence of the photocurrent without Seebeck contribution shows a\nsign reversal from negative to positive at a specific temperature depending on\nthe wavelength of photoexcitation light."
    },
    {
        "anchor": "Coupled wire construction of chiral spin liquids: We develop a coupled wire construction of chiral spin liquids. The starting\npoint are individual wires of electrons in the Mott regime that are subject to\na Zeeman field and Rashba spin-orbit coupling. Suitable spin-flip couplings\nbetween the wires yield an Abelian chiral spin liquid state which supports\nspinon excitations above a bulk gap, and chiral edge states. The approach\ngeneralizes to non-Abelian chiral spin liquids at level k with parafermionic\nedge states.",
        "positive": "Diameter-dependent conductance of InAs nanowires: Electrical conductance through InAs nanowires is relevant for electronic\napplications as well as for fundamental quantum experiments. Here we employ\nnominally undoped, slightly tapered InAs nanowires to study the diameter\ndependence of their conductance. Contacting multiple sections of each wire, we\ncan study the diameter dependence within individual wires without the need to\ncompare different nanowire batches. At room temperature we find a\ndiameter-independent conductivity for diameters larger than 40 nm, indicative\nof three-dimensional diffusive transport. For smaller diameters, the resistance\nincreases considerably, in coincidence with a strong suppression of the\nmobility. From an analysis of the effective charge carrier density, we find\nindications for a surface accumulation layer."
    },
    {
        "anchor": "On-chip interference of single photons from an embedded quantum dot and\n  an external laser: In this work, we demonstrate the on-chip two-photon interference between\nsingle photons emitted by a single self-assembled InGaAs quantum dot and an\nexternal laser. The quantum dot is embedded within one arm of an air-clad\ndirectional coupler which acts as a beam-splitter for incoming light. Photons\noriginating from an attenuated external laser are coupled to the second arm of\nthe beam-splitter and then combined with the quantum dot photons, giving rise\nto two-photon quantum interference between dissimilar sources. We verify the\noccurrence of on-chip Hong-Ou-Mandel interference by cross-correlating the\noptical signal from the separate output ports of the directional coupler. This\nexperimental approach allows us to use classical light source (laser) to assess\nin a single step the overall device performance in the quantum regime and probe\nquantum dot photon indistinguishability on application realistic time scales.",
        "positive": "Dephasing of Exchange-coupled Spins in Quantum Dots for Quantum\n  Computing: A spin qubit in semiconductor quantum dots holds promise for quantum\ninformation processing for scalability and long coherence time. An important\nsemiconductor qubit system is a double quantum dot trapping two electrons or\nholes, whose spin states encode either a singlet-triplet qubit or two\nsingle-spin qubits coupled by exchange interaction. In this article, we report\nprogress on spin dephasing of two exchange-coupled spins in a double quantum\ndot. We first discuss the schemes of two-qubit gates and qubit encodings in\ngate-defined quantum dots or donor atoms based on the exchange interaction.\nThen, we report the progress on spin dephasing of a singlet-triplet qubit or a\ntwo-qubit gate. The methods of suppressing spin dephasing are further\ndiscussed. The understanding of spin dephasing may provide insights into the\nrealization of high-fidelity quantum gates for spin-based quantum computing."
    },
    {
        "anchor": "Single photon emitters with polarization and orbital angular momentum\n  locking in monolayer semiconductors: Excitons in monolayer transition metal dichalcogenide are endowed with\nintrinsic\n  valley-orbit coupling between their center-of-mass motion and valley\npseudospin.\n  When trapped in a confinement potential, e.g., generated by strain field, we\nfind\n  that intralayer excitons are valley and orbital\n  angular momentum (OAM) entangled. By tuning trap profile and external\nmagnetic\n  field, one can engineer the exciton states at ground state, and realize a\n  series of valley-OAM entangled states. We further show that the OAM of\nexcitons can be\n  transferred to emitted photons, and these novel\n  exciton states can naturally serve as polarization-OAM locked single photon\n  emitters, which under certain circumstance become polarization-OAM entangled,\n  highly tunable by strain trap and magnetic field. Our proposal\n  demonstrates a novel scheme to generate polarization-OAM locked/entangled\n  photons at nanoscale with high degree of integrability and tunability,\npointing to exciting\n  opportunities for quantum information applications.",
        "positive": "Entanglement between static and flying qubits in an Aharonov-Bohm double\n  electrometer: We consider the phase-coherent transport of electrons passing through an\nAharonov-Bohm ring while interacting with a tunnel charge in a double quantum\ndot (representing a charge qubit) which couples symmetrically to both arms of\nthe ring. For Aharonov-Bohm flux Phi_AB=h/2e we find that electrons can only be\ntransmitted when they flip the charge qubit's pseudospin parity an odd number\nof times. The perfect correlations of the dynamics of the pseudospin and\nindividual electronic transmission and reflection events can be used to\nentangle the charge qubit with an individual passing electron."
    },
    {
        "anchor": "Phase transitions in the boson-fermion resonance model in one dimension: We study 1D fermions with photoassociation or with a narrow Fano-Feshbach\nresonance described by the Boson-Fermion resonance model. Using thebosonization\ntechnique, we derive a low-energy Hamiltonian of the system. We show that at\nlow energy, the order parameters for the Bose Condensation and fermion\nsuperfluidity become identical, while a spin gap and a gap against the\nformation of phase slips are formed. As a result of these gaps, charge density\nwave correlations decay exponentially in contrast with the phases where only\nbosons or only fermions are present. We find a Luther-Emery point where the\nphase slips and the spin excitations can be described in terms of\npseudofermions. This allows us to provide closed form expressions of the\ndensity-density correlations and the spectral functions. The spectral functions\nof the fermions are gapped, whereas the spectral functions of the bosons remain\ngapless. The application of a magnetic field results in a loss of coherence\nbetween the bosons and the fermion and the disappearance of the gap. Changing\nthe detuning has no effect on the gap until either the fermion or the boson\ndensity is reduced to zero. Finally, we discuss the formation of a Mott\ninsulating state in a periodic potential. The relevance of our results for\nexperiments with ultracold atomic gases subject to one-dimensional confinement\nis also discussed.",
        "positive": "Floquet engineering of magnetic topological insulator MnBi$_2$Te$_4$\n  films: Floquet engineering is an important way to manipulate the electronic states\nof condensed matter physics. Recently, the discovery of the magnetic\ntopological insulator MnBi$_2$Te$_4$ and its family provided a valuable\nplatform to study magnetic topological phenomena, such as, the quantum\nanomalous Hall effect, the axion insulator state and the topological\nmagnetoelectric effect. In this work, based on the effective model and\nfirst-principles calculations in combination with the Floquet theory, we reveal\nthat the circularly polarized light (CPL) induces the sign reversal of the\nChern number of odd-septuple-layer (SL) MnBi$_2$Te$_4$ thin films. In contrast,\nthe CPL drives the axion insulator state into the quantum anomalous Hall state\nin even-SL MnBi$_2$Te$_4$ thin films. More interestingly, if the topmost van\nder Waals gap between the surface layer and the below bulk in MnBi$_2$Te$_4$\nfilms is slightly expanded, a high Chern number $|C|=2$ can be realized under\nthe CPL. Our work demonstrates that the light can induce rich magnetic\ntopological phases in MnBi$_2$Te$_4$ films, which might have potential\napplications in optoelectronic devices."
    },
    {
        "anchor": "Topological energy braiding of the non-Bloch bands: The non-Hermitian skin effect, as a unique feature of non-Hermitian systems,\nwill break the topological energy braiding of the Bloch bands in open boundary\nsystems. Going beyond the Bloch band theory, we unveil the energy braiding of\nthe non-Bloch bands by introducing a one-dimensional non-Hermitian\ntight-binding model. We find an entirely new generic class of topological\nnon-Bloch bands such as Hopf link, which is generally generated by the\nnon-Hermitian skin effect. The energy braiding is topologically robust against\nany perturbations without gap closing. Furthermore, non-Bloch topological\ninvariants are proposed based on the generalized Brillouin zone to characterize\nthe topology of these non-Bloch bands. The topological phase transition between\nthe distinct phases occurs with the non-Bloch bands touching at exceptional\npoints. We hope that our work can shed light on the topological energy braiding\nof the non-Bloch bands for non-Hermitian systems.",
        "positive": "Spin transparency for an interface of an ultrathin magnet within the\n  spin dephasing length: We examine a modified drift-diffusion formalism to describe spin transport\nnear an ultrathin magnet whose thickness is similar to or less than the spin\ndephasing length. Most of the previous theories on spin torque assume the\ntransverse component of a injected spin current dephases perfectly thus are\nfully absorbed into the ferromagnet. However, in the state-of-art multilayer\nsystems under consideration of recent studies, the thicknesses of ferromagnets\nare on the order of or less than a nanometer, thus one cannot safely assume the\nspin dephasing to be perfect. To describe the effects of a finite dephasing\nrate, we adopt the concept of transmitted mixing conductance, whose application\nto the drift-diffusion formalism has been limited. For a concise description of\nphysical consequences, we introduce an effective spin transparency.\nInterestingly, for an ultrathin magnet with a finite dephasing rate, the spin\ntransparency can be even enhanced and there arises a non-negligible field-like\nspin-orbit torque even in the absence of the imaginary part of the spin mixing\nconductance. The effective spin transparency provides a simple extension of the\ndrift-diffusion formalism, which is accessible to experimentalists analyzing\ntheir results."
    },
    {
        "anchor": "Demagnetization Borne Microscale Skyrmions: Magnetic systems are an exciting realm of study that is being explored on\nsmaller and smaller scales. One extremely interesting magnetic state that has\ngained momentum in recent years is the skyrmionic state. It is characterized by\na vortex where the edge magnetic moments point opposite to the core. Although\nskyrmions have many possible realizations, in practice, creating them in a lab\nis a difficult task to accomplish. In this work, new methods for skyrmion\ngeneration and customization are suggested. Skyrmionic behavior was numerically\nobserved in minimally customized simulations of spheres, hemisphere,\nellipsoids, and hemi-ellipsoids, for typ- ical Cobalt parameters, in a range\nfrom approximately 40 nm to 120 nm in diameter simply by applying a field.",
        "positive": "Electrical-equivalent van der Waals gap for 2D bilayers: Vertical stacks of two-dimensional (2D) materials, separated by the van der\nWaals gap and held together by the van der Waals forces, are immensely\npromising for a plethora of nanotechnological applications. Charge control in\nthese stacks may be modeled using either a simple electrostatics approach or a\ndetailed atomistic one. In this paper, we compare these approaches for a gated\n2D transition metal dichalcogenide bilayer and show that recently reported\nelectrostatics-based models of this system give large errors in band energy\ncompared to atomistic (Density Functional Theory) simulations. These errors are\ndue to the tails of the ionic potentials that reduce the electrical-equivalent\nvan der Waals gap between the 2D layers, and can be corrected by using the\nreduced gap in the electrostatic model. For a physical van der Waals gap\n(defined as the chalcogen to chalcogen distance) of 3 $\\mathrm{\\AA}$ in a 2D\nbilayer, the electrical-equivalent gap is less than 1 $\\mathrm{\\AA}$. For the\nexample of band-to-band tunneling based ultra low-power transistors, this is\nseen to lead to errors of several hundred millivolts and more in the threshold\nvoltage estimated from electrostatics."
    },
    {
        "anchor": "Tomonaga-Luttinger liquids and Coulomb blockade in multiwall carbon\n  nanotubes under pressure: We report that the conductance of macroscopic multiwall nanotube (MWNT)\nbundles under pressure shows power laws in temperature and voltage, as\ncorresponding to a network of bulk-bulk connected Tomonaga-Luttinger Liquids\n(LL). Contrary to individual MWNT, where the observed power laws are attributed\nto Coulomb blockade, the measured ratio for the end and bulk obtained\nexponents, ~2.4, can only be accounted for by LL theory. At temperatures\ncharacteristic of interband separation, it increases due to thermal population\nof the conducting sheets unoccupied bands.",
        "positive": "The effect of the spin-orbit geometric phase on the spectrum of\n  Aharonov-Bohm oscillations in a semiconductor mesoscopic ring: Taking into account the spin precession caused by the spin-orbit splitting of\nthe conduction band in semiconductor quantum wells, we have calculated the\nFourier spectra of conductance and state-density correlators in a 2D ring, in\norder to investigate the structure of the main peak corresponding to\nAharonov-Bohm oscillations. In narrow rings the peak structure is determined by\nthe competition between the spin-orbit and the Zeeman couplings. The latter\nleads to a peak broadening, and produces the peak splitting in the\nstate-density Fourier spectrum. We have found an oscillation of the peak\nintensity as a function of the spin-orbit coupling constant, and this effect of\nthe quantum interference caused by the spin geometric phase is destroyed with\nincreasing Zeeman coupling."
    },
    {
        "anchor": "Ultrafast single-pulse all-optical switching in synthetic ferrimagnetic\n  Tb/Co/Gd multilayers: In this work, we investigate single-shot all-optical switching (AOS) in\nTb/Co/Gd/Co/Tb multilayers in an attempt to establish AOS in synthetic\nferrimagnets with high perpendicular magnetic anisotropy. In particular, we\nstudy the effect of varying Tb thicknesses to disentangle the role of the two\nrare earth elements. Even though the role of magnetic compensation has been\nconsidered to be crucial, we find that the threshold fluence for switching is\nlargely independent of the Tb content. Moreover, we identify the timescale for\nthe magnetization to cross zero to be within the first ps after laser\nexcitation using time-resolved MOKE. We conclude that the switching is governed\nmostly by interactions between Co and Gd.",
        "positive": "Charge nonconservation of molecular devices in the presence of a\n  nonlocal potential: In the presence of a nonlocal potential in molecular device systems,\ngenerally the charge conservation cannot be satisfied, and in literatures the\nmodifications of the conventional definition of current were given to solve\nthis problem. We demonstrate that, however, the nonconservation is not due to\nthe invalidation of the conventional definition of current, but originates\nrespectively from the improper approximations to electron-electron interactions\nand the inappropriate definition of current using pseudo wave functions in\npseudopotential implementations. In this work, we propose a nonlocal-potential\nformulation of the interactions to fulfill the charge conservation and also\ngive a discussion about the calculation of current when the pseudopotential is\ninvolved. As an example of application of our formulation, we further present\nthe calculated results of a double-barrier model."
    },
    {
        "anchor": "Resonant translational, breathing and twisting modes of pinned\n  transverse magnetic domain walls: We study translational, breathing and twisting resonant modes of transverse\nmagnetic domain walls pinned at notches in ferromagnetic nanostrips. We\ndemonstrate that a mode's sensitivity to notches depends strongly on the\ncharacteristics of that particular resonance. For example, the frequencies of\nmodes involving lateral motion of the wall are the ones which are most\nsensitive to changes in the notch intrusion depth (especially at the narrower,\nmore strongly confined end of the domain wall). In contrast, the breathing\nmode, whose dynamics are concentrated away from the notches is relatively\ninsensitive to changes in the notches' sizes. We also demonstrate a sharp drop\nin the translational mode's frequency towards zero when approaching depinning\nwhich is found, using a harmonic oscillator model, to be consistent with a\nreduction in the local slope of the notch-induced confining potential at its\nedge.",
        "positive": "Nanomechanical characterization of the Kondo charge dynamics in a carbon\n  nanotube: Using the transversal vibration resonance of a suspended carbon nanotube as\ncharge detector for its embedded quantum dot, we investigate the case of strong\nKondo correlations between a quantum dot and its leads. We demonstrate that\neven when large Kondo conductance is carried at odd electron number, the\ncharging behaviour remains similar between odd and even quantum dot occupation.\nWhile the Kondo conductance is caused by higher order processes, a sequential\ntunneling only model can describe the time-averaged charge. The gate potentials\nof maximum current and fastest charge increase display a characteristic\nrelative shift, which is suppressed at increased temperature. These\nobservations agree very well with models for Kondo-correlated quantum dots."
    },
    {
        "anchor": "Nanoscale magnetic field sensing with spin-Hall nano-oscillator devices: In this work, we develop a nanoscale magnetic field sensor based on a\nspin-Hall nano-oscillator (SHNO) device. We fabricate constriction-based SHNO\ndevices using Ni$_{81}$Fe$_{19}$/Au$_{0.25}$Pt$_{0.75}$ bilayer and use them to\ndemonstrate quasi-DC sensing up to kilohertz-scale frequencies under a bias\nfield of 400 Oe in the sample plane. The magnetic field sensing is based on the\nlinear dependence of SHNO oscillation frequency on external magnetic field. The\ndetectivity of the sensor is as low as 0.21 $\\mu$T/$\\sqrt{\\mbox{Hz}}$ at 100\nHz, with an effective sensing area of 0.32 $\\mu$m$^2$, making SHNO devices\nsuitable for scanning probe nanoscale magnetometry.",
        "positive": "Tunable Transient Decay Times in Nonlinear Systems: Application to\n  Magnetic Precession: The dynamical motion of the magnetization plays a key role in the properties\nof magnetic materials. If the magnetization is initially away from the\nequilibrium direction in a magnetic nanoparticle, it will precess at a natural\nfrequency and, with some damping present, will decay to the equilibrium\nposition in a short lifetime. Here we investigate a simple but important\nsituation where a magnetic nanoparticle is driven non-resonantly by an\noscillating magnetic field, not at the natural frequency. We find a surprising\nresult that the lifetime of the transient motion is strongly tunable, by\nfactors of over 10,000, by varying the amplitude of the driving field."
    },
    {
        "anchor": "Nonlinear optical selection rules of excitons in monolayer transition\n  metal dichalcogenides: We propose an analytical approach for calculating the linear and nonlinear\noptical (NLO) responses of monolayer transition metal dichalcogenides (TMDs)\nincluding excitonic effects. An effective Hamiltonian reproducing the trigonal\nwarping (TW) of the energy dispersion, is used to derive analytical expressions\nfor excitonic matrix elements. Based on this approach, we provide an\ninformative diagram, which encompasses all excitonic selection rules. The\ndiagram enables us to identify main transitions for the first-, second- and\nthird-order optical responses. As a case study, we calculate the optical\nconductivity and second/third harmonic generation responses of monolayer MoS2\nand demonstrate that the analytical approach accurately reproduces the spectra\nobtained using the Bethe-Salpeter equation (BSE). Therefore, the analytical\napproach provides an efficient and reliable method for calculating the NLO\nspectra as accurate as the full BSE method. Moreover, it enables us to obtain\nvaluable physical insight into the fundamental transitions responsible for\nindividual resonances, which is not straightforward in the full BSE method.",
        "positive": "Interaction-induced magnetoresistance: From the diffusive to the\n  ballistic regime: We study interaction-induced quantum correction to the conductivity tensor of\nelectrons in two dimensions for arbitrary T tau, where T is the temperature and\ntau the transport mean free time. A general formula is derived, expressing the\ncorrection in terms of classical propagators (\"ballistic diffusons\"). The\nformalism is used to calculate the interaction contribution to the\nmagnetoresistance in a classically strong transverse field and smooth disorder\nin the whole range of temperatures from the diffusive (T tau<<1) to the\nballistic (T tau>1) regime."
    },
    {
        "anchor": "Possibility of adiabatic transport of a Majorana edge state through an\n  extended gapless region: In the context of slow quenching dynamics of a $p$-wave superconducting\nchain, it has been shown that a Majorana edge state can not be adiabatically\ntransported from one topological phase to the other separated by a quantum\ncritical line. On the other hand, the inclusion of a phase factor in the\nhopping term, that breaks the extended time reversal invariance, results in an\nextended gapless region between two topological phases. We show that for a\nfinite chain with an open boundary condition there exists a non-zero\nprobability that an edge Majorana can be adiabatically transported from one\ntopological phase to the other across this gapless region following a slow\nquench of the superconducting term; this happens for an optimum transit time,\nthat is proportional to the system size and diverges for a thermodynamically\nlarge chain. We attribute this phenomenon to the mixing of the Majorana only\nwith low-lying inverted bulk states.",
        "positive": "Low disordered, stable, and shallow germanium quantum wells: a\n  playground for spin and hybrid quantum technology: Buried-channel semiconductor heterostructures are an archetype material\nplatform to fabricate gated semiconductor quantum devices. Sharp confinement\npotential is obtained by positioning the channel near the surface, however\nnearby surface states degrade the electrical properties of the starting\nmaterial. In this paper we demonstrate a two-dimensional hole gas of high\nmobility ($5\\times 10^{5}$ cm$^2$/Vs) in a very shallow strained germanium\nchannel, which is located only 22 nm below the surface. This high mobility\nleads to mean free paths $\\approx6 \\mu m$, setting new benchmarks for holes in\nshallow FET devices. Carriers are confined in an undoped Ge/SiGe\nheterostructure with reduced background contamination, sharp interfaces, and\nhigh uniformity. The top-gate of a dopant-less field effect transistor controls\nthe carrier density in the channel. The high mobility, along with a percolation\ndensity of $1.2\\times 10^{11}\\text{ cm}^{-2}$, light effective mass (0.09\nm$_e$), and high g-factor (up to $7$) highlight the potential of undoped\nGe/SiGe as a low-disorder material platform for hybrid quantum technologies."
    },
    {
        "anchor": "Fractional Quantum Hall Effect at Landau Level Filling nu=4/11: We report low temperature electronic transport results on the fractional\nquantum Hall effect of composite fermions at Landau level filling nu = 4/11 in\na very high mobility and low density sample. Measurements were carried out at\ntemperatures down to 15mK, where an activated magnetoresistance Rxx and a\nquantized Hall resistance Rxy, within 1% of the expected value of h/(4/11)e^2,\nwere observed. The temperature dependence of the Rxx minimum at 4/11 yields an\nactivation energy gap of ~ 7 mK. Developing Hall plateaus were also observed at\nthe neighboring states at nu = 3/8 and 5/13.",
        "positive": "Generalized Clustering Conditions of Jack Polynomials at Negative Jack\n  Parameter $\u03b1$: We present several conjectures on the behavior and clustering properties of\nJack polynomials at \\emph{negative} parameter $\\alpha=-\\frac{k+1}{r-1}$, of\npartitions that violate the $(k,r,N)$ admissibility rule of Feigin \\emph{et.\nal.} [\\onlinecite{feigin2002}]. We find that \"highest weight\" Jack polynomials\nof specific partitions represent the minimum degree polynomials in $N$\nvariables that vanish when $s$ distinct clusters of $k+1$ particles are formed,\nwith $s$ and $k$ positive integers. Explicit counting formulas are conjectured.\nThe generalized clustering conditions are useful in a forthcoming description\nof fractional quantum Hall quasiparticles."
    },
    {
        "anchor": "Coherent control of a nanomechanical two-level system: The Bloch sphere is a generic picture describing a coupled two-level system\nand the coherent dynamics of its superposition states under control of\nelectromagnetic fields. It is commonly employed to visualise a broad variety of\nphenomena ranging from spin ensembles and atoms to quantum dots and\nsuperconducting circuits. The underlying Bloch equations describe the state\nevolution of the two-level system and allow characterising both energy and\nphase relaxation processes in a simple yet powerful manner.\n  Here we demonstrate the realisation of a nanomechanical two-level system\nwhich is driven by radio frequency signals. It allows to extend the above Bloch\nsphere formalism to nanoelectromechanical systems. Our realisation is based on\nthe two orthogonal fundamental flexural modes of a high quality factor\nnanostring resonator which are strongly coupled by a dielectric gradient field.\nFull Bloch sphere control is demonstrated via Rabi, Ramsey and Hahn echo\nexperiments. This allows manipulating the classical superposition state of the\ncoupled modes in amplitude and phase and enables deep insight into the\ndecoherence mechanisms of nanomechanical systems. We have determined the energy\nrelaxation time T1 and phase relaxation times T2 and T2*, and find them all to\nbe equal. This not only indicates that energy relaxation is the dominating\nsource of decoherence, but also demonstrates that reversible dephasing\nprocesses are negligible in such collective mechanical modes. We thus conclude\nthat not only T1 but also T2 can be increased by engineering larger mechanical\nquality factors. After a series of ground-breaking experiments on ground state\ncooling and non-classical signatures of nanomechanical resonators in recent\nyears, this is of particular interest in the context of quantum information\nprocessing.",
        "positive": "Behaviour of three charged particles on a plane under perpendicular\n  magnetic field: We consider the problem of three identical charged particles on a plane under\na perpendicular magnetic field and interacting through Coulomb repulsion. This\nproblem is treated within Taut's framework, in the limit of vanishing center of\nmass vector $\\vec{R} \\to \\vec{0}$, which corresponds to the strong magnetic\nfield limit, occuring for example in the Fractional Quantum Hall Effect. Using\nthe solutions of the biconfluent Heun equation, we compute the eigenstates and\nshow that there is two sets of solutions. The first one corresponds to a system\nof three independent anyons which have their angular momenta fixed by the value\nof the magnetic field and specified by a dimensionless parameter $C \\simeq\n\\frac{l_B}{l_0}$, the ratio of $l_B$, the magnetic length, over $l_0$, the Bohr\nradius. This anyonic character, consistent with quantum mechanics of identical\nparticles in two dimensions, is induced by competing physical forces. The\nsecond one corresponds to the case of the Landau problem when $C \\to 0$.\nFinally we compare these states with the quantum Hall states and find that the\nLaughlin wave functions are special cases of our solutions under certains\nconditions."
    },
    {
        "anchor": "Static polarizability of two-dimensional hole gases: We have calculated the density-density (Lindhard) response function of a\nhomogeneous two-dimensional (2D) hole gas in the static (omega=0) limit. The\nbulk valence-band structure comprising heavy-hole (HH) and light-hole (LH)\nstates is modeled using Luttinger's kdotp approach within the axial\napproximation. We elucidate how, in contrast to the case of conduction\nelectrons, the Lindhard function of 2D holes exhibits unique features\nassociated with (i) the confinement-induced HH-LH energy splitting and (ii) the\nHH-LH mixing arising from the charge carriers' in-plane motion. Implications\nfor the dielectric response and related physical observables are discussed.",
        "positive": "Selected graphenelike zigzag nanoribbons with chemically functionalized\n  edges: Implications for electronic and magnetic properties: It is known that there is a wide class of quasi-two-dimensional graphenelike\nnanomaterials which in many respects can outperform graphene. So, here in\naddition to graphene, the attention is directed to stanene (buckled honeycomb\nstructure) and phosphorene (puckered honeycomb structure). It is shown that,\ndepending on the doping, these materials can have magnetically ordered edges.\nComputed diagrams of magnetic phases illustrate that, on the one hand, n-type\ndoped narrow zigzag nanoribbons of graphene and stanene have\nantiferromagnetically aligned magnetic moments between the edges. On the other\nhand, however, in the case of phosphorene nanoribbons the zigzag edges can have\nferromagnetically aligned magnetic moments for the p-type doping. The edge\nmagnetism critically influences transport properties of the nanoribbons, and if\nadequately controlled can make them attractive for spintronics."
    },
    {
        "anchor": "Ferromagnetic order in dipolar systems with anisotropy: application to\n  magnetic nanoparticle supracrystals: Single domain magnetic nanoparticles (MNP) interacting through dipolar\ninteractions (DDI) in addition to the magnetocrystalline energy may present a\nlow temperature ferromagnetic (SFM) or spin glass (SSG) phase according to the\nunderlying structure and the degree of order of the assembly. We study, from\nMonte Carlo simulations in the framework of the effective one-spin or macrospin\nmodels, the case of a monodisperse assembly of single domain MNP fixed on the\nsites of a perfect lattice with fcc symmetry and randomly distributed easy\naxes. We limit ourselves to the case of a low anisotropy, namely the onset of\nthe disappearance of the dipolar long-range ferromagnetic (FM) phase obtained\nin the absence of anisotropy due to the disorder introduced by the latter.",
        "positive": "Magnetization fluctuations and magnetic aftereffect probed via the\n  anomalous Hall effect: Taking advantage of the anomalous Hall effect, we electrically probe\nlow-frequency magnetization fluctuations at room temperature in a thin\nferromagnetic Pt/Co/AlO$_x$ layer stack with perpendicular magnetic anisotropy.\nWe observe a strong enhancement of the Hall voltage fluctuations within the\nhysteretic region of the magnetization loop. Analyzing both the temporal\nevolution of the anomalous Hall voltage and its frequency-dependent noise power\ndensity, we identify two types of magnetic noise: abrupt changes in the\nmagnetic domain configuration, evident as Barkhausen-like steps in the Hall\nvoltage time trace, yield a noise power density spectrum scaling with frequency\nas $1/f^{\\beta}$ with $\\beta\\approx 1.9$. In contrast, quasi-stationary\nmagnetization configurations are connected with a magnetic noise power density\nwith an exponent $\\beta\\approx 0.9$. The observation of Barkausen steps and\nrelaxation effects shows that the magnetic system is in a non-stationary state\nin the hysteresis region, such that the fluctuation-dissipation theorem cannot\nbe expected to hold. However, the time-dependent change in the Hall voltage for\nconstant magnetic field strength resembles the integrated noise power."
    },
    {
        "anchor": "Gap oscillations and Majorana bound states in magnetic chains on\n  superconducting honeycomb lattices: Magnetic chains on superconducting systems have emerged as a platform for\nrealization of Majorana bound states (MBSs) in condensed matter systems with\npossible applications to topological quantum computation. In this work we study\nthe MBSs formed in magnetic chains on two-dimensional honeycomb materials with\ninduced superconductivity. We establish phase diagrams showing the topological\nregions (where MBSs appear), which are strongly dependent on the spiral angle\nalong the chain of the magnetic moments. In particular, find large regions\nwhere the topological phase is robust even at large values of the local Zeeman\nfield, thus producing topological regions without an upper bound. Moreover, we\nshow that the energy oscillations of the MBSs can show very different behavior\nwith magnetic field strength. In some parameter regimes we find increasing\noscillations amplitudes and decreasing periods, while in the other regimes the\ncomplete opposite behavior is found with increasing magnetic field strength. We\nalso find that the topological phase can become dependent on the chain length,\nparticularly in topological regions with a very high or no upper bound. In\nthese systems we see a very smooth evolution from MBSs localized at chain end\npoints to in-gap Andreev bound states spread over the full chain.",
        "positive": "Bulk-edge correspondence and new topological phases in periodically\n  driven spin-orbit coupled materials in the low frequency limit: We study the topological phase transitions induced in spin-orbit coupled\nmaterials with buckling like silicene, germanene, stanene, etc, by circularly\npolarised light, beyond the high frequency regime, and unearth many new\ntopological phases. These phases are characterised by the spin-resolved\ntopological invariants, $C_0^\\uparrow$, $C_0^\\downarrow$, $C_\\pi^\\uparrow$ and\n$C_\\pi^\\downarrow$, which specify the spin-resolved edge states traversing the\ngaps at zero quasi-energy and the Floquet zone boundaries respectively. We show\nthat for each phase boundary, and independently for each spin sector, the gap\nclosure in the Brillouin zone occurs at a high symmetry point."
    },
    {
        "anchor": "Mechanically activated ionic transport across single-digit carbon\n  nanotubes: Fluid and ionic transport at nanoscale recently highlighted a wealth of\nexotic behaviours. However, the artificial nanofluidic devices are still far\nfrom the advanced functionalities existing in biological systems, such as\nelectrically and mechanically activated transport. Here we focus on the ionic\ntransport through 2 nm-radius individual multiwalled carbon nanotubes (CNT),\nunder the combination of mechanical and electrical forcings. Our findings\nevidence mechanically activated ionic transport under the form of an ionic\nconductance which depends quadratically on the applied pressure. Our\ntheoretical study relates this behaviour with the complex interplay between\nelectrical and mechanical drivings, and shows that the superlubricity of CNT is\na prerequisite to attain mechanically activated transport. The pressure\nsensitivity shares similarities with the response of biological\nmechanosensitive ion channels observed here for the first time in an artificial\nsystem. This paves the way to build new active nanofluidic functionalities\ninspired by the complex biological machinery.",
        "positive": "Multi-slot optical Yagi-Uda antenna for efficient unidirectional\n  radiation to free space: Plasmonic nanoantennas are key elements in nanophotonics capable of directing\nradiation or enhancing the transition rate of a quantum emitter. Slot-type\nmagnetic-dipole nanoantennas, which are complementary structures of typical\nelectric-dipole-type antennas, have received little attention, leaving their\nantenna properties largely unexplored. Here we present a novel\nmagnetic-dipole-fed multi-slot optical Yagi-Uda antenna. By engineering the\nrelative phase of the interacting surface plasmon polaritons between the slot\nelements, we demonstrate that the optical antenna exhibits highly\nunidirectional radiation to free space. The unique features of the slot-based\nmagnetic nanoantenna provide a new possibility of achieving integrated features\nsuch as energy transfer from one waveguide to another by working as a future\noptical via."
    },
    {
        "anchor": "Analytical study of nano-scale logical operations: A complete analytical prescription is given to perform three basic (OR, AND,\nNOT) and two universal (NAND, NOR) logic gates at nano-scale level using simple\ntailor made geometries. Two different geometries, ring-like and chain-like, are\ntaken into account where in each case the bridging conductor is coupled to a\nlocal atomic site through a dangling bond whose site energy can be controlled\nby means of external gate electrode. The main idea is that when injecting\nelectron energy matches with site energy of local atomic site transmission\nprobability drops exactly to zero, whereas the junction exhibits finite\ntransmission for other energies. Utilizing this prescription we perform logical\noperations, and, we strongly believe that the proposed results can be verified\nin laboratory. Finally, we numerically compute two-terminal transmission\nprobability considering general models and the numerical results matches\nexactly well with our analytical findings.",
        "positive": "Giant Hall Switching by Surface-State-Mediated Spin-Orbit Torque in a\n  Hard Ferromagnetic Topological Insulator: Topological insulators (TI) and magnetic topological insulators (MTI) can\napply highly efficient spin-orbit torque (SOT) and manipulate the magnetization\nwith their unique topological surface states with ultra-high efficiency. Here,\nwe demonstrate efficient SOT switching of a hard MTI, V-doped (Bi,Sb)2Te3\n(VBST) with a large coercive field that can prevent the influence of an\nexternal magnetic field. A giant switched anomalous Hall resistance of 9.2\n$k\\Omega$ is realized, among the largest of all SOT systems. The SOT switching\ncurrent density can be reduced to $2.8\\times10^5 A/cm^2$. Moreover, as the\nFermi level is moved away from the Dirac point by both gate and composition\ntuning, VBST exhibits a transition from edge-state-mediated to\nsurface-state-mediated transport, thus enhancing the SOT effective field to\n$1.56\\pm 0.12 T/ (10^6 A/cm^2)$ and the interfacial charge-to-spin conversion\nefficiency to $3.9\\pm 0.3 nm^{-1}$ (nominal spin Hall angle to $23.2\\pm 1.8$).\nThe findings establish VBST as an extraordinary candidate for energy-efficient\nmagnetic memory devices."
    },
    {
        "anchor": "Partial local density of states from scanning gate microscopy: Scanning gate microscopy images from measurements made in the vicinity of\nquantum point contacts were originally interpreted in terms of current flow.\nSome recent work has analytically connected the local density of states to\nconductance changes in cases of perfect transmission, and at least\nqualitatively for a broader range of circumstances. In the present paper, we\nshow analytically that in any time-reversal invariant system there are\nimportant deviations that are highly sensitive to imperfect transmission.\nNevertheless, the unperturbed partial local density of states can be extracted\nfrom a weakly invasive scanning gate microscopy experiment, provided the\nquantum point contact is tuned anywhere on a conductance plateau. A\nperturbative treatment in the reflection coefficient shows just how sensitive\nthis correspondence is to the departure from the quantized conductance value\nand reveals the necessity of local averaging over the tip position. It is also\nshown that the quality of the extracted partial local density of states\ndecreases with increasing tip radius.",
        "positive": "Compressed optimization of device architectures: Note: This preprint has been superseded by arXiv:1806.04318.\n  Recent advances in nanotechnology have enabled researchers to control\nindividual quantum mechanical objects with unprecedented accuracy, opening the\ndoor for both quantum and extreme-scale conventional computing applications. As\nthese devices become larger and more complex, the ability to design them such\nthat they can be simply controlled becomes a daunting and computationally\ninfeasible task. Here, motivated by ideas from compressed sensing, we introduce\na protocol for the Compressed Optimization of Device Architectures (CODA). It\nleads naturally to a metric for benchmarking device performance and optimizing\ndevice designs, and provides a scheme for automating the control of gate\noperations and reducing their complexity. Because CODA is computationally\nefficient, it is readily extensible to large systems. We demonstrate the CODA\nbenchmarking and optimization protocols through simulations of up to eight\nquantum dots in devices that are currently being developed experimentally for\nquantum computation."
    },
    {
        "anchor": "Second Harmonic Generation of cuprous oxide in magnetic fields: Recently Second Harmonic Generation (SHG) for the yellow exciton series in\ncuprous oxide has been demonstrated [J. Mund et al., Phys. Rev. B 98, 085203\n(2018)]. Assuming perfect $O_{\\mathrm{h}}$ symmetry, SHG is forbidden along\ncertain high-symmetry axes. Perturbations can break this symmetry and forbidden\ntransitions may become allowed. We investigate theoretically the effect of\nexternal magnetic fields on the yellow exciton lines of cuprous oxide. We\nidentify two mechanisms by which an applied magnetic field can induce a second\nharmonic signal in a forbidden direction. First of all, a magnetic field by\nitself generally lifts the selection rules. In the Voigt configuration, an\nadditional magneto-Stark electric field appears. This also induces certain SHG\nprocesses differing from those induced by the magnetic field alone.\nComplementary to the manuscript by A. Farenbruch et al. [Phys. Rev. B,\nsubmitted], we perform a full numerical diagonalization of the exciton\nHamiltonian including the complex valence band structure. Numerical results are\ncompared with experimental data.",
        "positive": "Finite-temperature Screening and the Specific Heat of Doped Graphene\n  Sheets: At low energies, electrons in doped graphene sheets are described by a\nmassless Dirac fermion Hamiltonian. In this work we present a semi-analytical\nexpression for the dynamical density-density linear-response function of\nnoninteracting massless Dirac fermions (the so-called \"Lindhard\" function) at\nfinite temperature. This result is crucial to describe finite-temperature\nscreening of interacting massless Dirac fermions within the Random Phase\nApproximation. In particular, we use it to make quantitative predictions for\nthe specific heat and the compressibility of doped graphene sheets. We find\nthat, at low temperatures, the specific heat has the usual normal-Fermi-liquid\nlinear-in-temperature behavior, with a slope that is solely controlled by the\nrenormalized quasiparticle velocity."
    },
    {
        "anchor": "Thermal entanglement and quantum coherence of a single electron in a\n  double quantum dot with Rashba Interaction: In this work, we study the thermal quantum coherence and fidelity in a\nsemiconductor double quantum dot. The device consists of a single electron in a\ndouble quantum dot with Rashba spin-orbit coupling in the presence of an\nexternal magnetic field. In our scenario, the thermal entanglement of the\nsingle electron is driven by the charge and spin qubits, the latter controlled\nby Rashba coupling. Analytical expressions are obtained for thermal concurrence\nand correlated coherence using the density matrix formalism. The main goal of\nthis work is to provide a good understanding of the effects of temperature and\nseveral parameters in quantum coherence. In addition, our findings show that we\ncan use the Rashba coupling to tune in the thermal entanglement, quantum\ncoherence, as well as, the thermal fidelity behavior of the system. Moreover,\nwe focus on the role played by thermal entanglement and correlated coherence\nresponsible for quantum correlations. We observe that the correlated coherence\nis more robust than the thermal entanglement in all cases, so quantum\nalgorithms based only on correlated coherence may be stronger than those based\non entanglement.",
        "positive": "Electrical polarization of nuclear spins in a breakdown regime of\n  quantum Hall effect: We have developed a method for electrical polarization of nuclear spins in\nquantum Hall systems. In a breakdown regime of odd-integer quantum Hall effect\n(QHE), excitation of electrons to the upper Landau subband with opposite spin\npolarity dynamically polarizes nuclear spins through the hyperfine interaction.\nThe polarized nuclear spins in turn accelerate the QHE breakdown, leading to\nhysteretic voltage-current characteristics of the quantum Hall conductor."
    },
    {
        "anchor": "Graphene-based topological insulator with an intrinsic bulk band gap\n  above room temperature: Topological insulators (TIs) represent a new quantum state of matter\ncharacterized by robust gapless states inside the insulating bulk gap. The\nmetallic edge states of a two-dimensional (2D) TI, known as quantum spin Hall\n(QSH) effect, are immune to backscattering and carry fully spin-polarized\ndissipationless currents. However, existing 2D TIs realized in HgTe and\nInAs/GaSb suffer from small bulk gaps (<10 meV) well below room temperature,\nthus limiting their application in electronic and spintronic devices. Here, we\nreport a new 2D TI comprising a graphene layer sandwiched between two Bi2Se3\nslabs that exhibits a large intrinsic bulk band gap of 30 to 50 meV, making it\nviable for room-temperature applications. Distinct from previous strategies for\nenhancing the intrinsic spin-orbit coupling effect of the graphene lattice, the\npresent graphene-based TI operates on a new mechanism of strong inversion\nbetween graphene Dirac bands and Bi2Se3 conduction bands. Strain engineering\nleads to effective control and substantial enhancement of the bulk gap.\nRecently reported synthesis of smooth graphene/Bi2Se3 interfaces demonstrates\nfeasibility of experimental realization of this new 2D TI structure, which\nholds great promise for nanoscale device applications.",
        "positive": "Quantum interference and structure-dependent orbital-filling effects on\n  the thermoelectric properties of quantum dot molecules: The quantum interference and orbital filling effects on the thermoelectric\n(TE) properties of quantum dot molecules with high figure of merit are\nillustrated via the full solution to the Hubbard- Anderson model in the Coulomb\nblockade regime. It is found that under certain condition in the triangular QD\nmolecule (TQDM), destructive quantum interference (QI) can occur, which leads\nto vanishing small electrical conductance, while the Seebeck coefficient is\nmodified dramatically. When TQDM is in the charge localization state due to QI,\nthe Seebeck coefficient is seriously suppressed at low temperature, but highly\nenhanced at high temperature. Meanwhile, the behavior of Lorenz number reveals\nthat it is easier to block charge transport via destructive QI than the\nelectron heat transport at high temperatures. The maximum power factor (PF) in\nTQDM occurs at full-filling condition. Nevertheless, low-filling condition is\npreferred for getting maximum PF in serially coupled triple QDs in general. In\ndouble QDs, the maximum PF can be achieved either with orbital-depletion or\norbital-filling as a result of electron-hole symmetry. Our theoretical work\nprovides a useful guideline for advancing the nanoscale TE technology."
    },
    {
        "anchor": "Response to Comment on: Tunneling in DNA with Spin Orbit coupling: The comment by O. Entin-Wohlman, A. Aharony, and Y. Utsumi, on our paper S.\nVarela, I. Zambrano, B. Berche, V. Mujica, and E. Medina, Phys. Rev. B 101,\n241410(R) (2020) makes a few points related to the validity of our model,\nespecially in the light of the interpretation of Bardarson's theorem: \"in the\npresence of time reversal symmetry and for half-integral spin the transmission\neigenvalues of the two terminal scattering matrix come in (Kramers) degenerate\npairs\". The authors of the comment first propose an ansatz for the wave\nfunction in the spin active region and go on to show that the resulting\ntransmission does not show spin dependence, reasoning that spin dependence\nwould violate Bardarson's assertion. Here we clearly show that the ansatz\npresented assumes spin-momentum independence from the outset and thus just\naddresses the spinless particle problem. We then find the appropriate\neigenfunction contemplating spin-momentum coupling and show that the resulting\nspectrum obeys Bardarson's theorem. Finally we show that the allowed\nwavevectors are the ones assumed in the original paper and thus the original\nconclusions follow. We recognize that the Hamiltonian in our paper written in\nlocal coordinates on a helix was deceptively simple and offer the expressions\nof how it should be written to more overtly convey the physics involved. The\nrelation between spin polarization and torque becomes clear, as described in\nour paper. This response is a very important clarification in relation to the\nimplications of Bardarson's theorem concerning the possibility of spin\npolarization in one dimensional systems in the linear regime.",
        "positive": "Mott scattering at the interface between a metal and a topological\n  insulator: We compute the spin-active scattering matrix and the local spectrum at the\ninterface between a metal and a three-dimensional topological band insulator.\nWe show that there exists a critical incident angle at which complete (100%)\nspin flip reflection occurs and the spin rotation angle jumps by $\\pi$. We\ndiscuss the origin of this phenomena, and systematically study the dependence\nof spin-flip and spin-conserving scattering amplitudes on the interface\ntransparency and metal Fermi surface parameters. The interface spectrum\ncontains a well-defined Dirac cone in the tunneling limit, and smoothly evolves\ninto a continuum of metal induced gap states for good contacts. We also\ninvestigate the complex band structure of Bi$_2$Se$_3$."
    },
    {
        "anchor": "Dynamics of 2D topological quadrupole insulator and Chern insulator\n  induced by real-space topological changes: The dynamics of two-dimensional (2D) topological quadrupole insulator (TQI)\nand Chern insulator (CI) after the real-space configuration is transformed from\na cylinder or Mobius strip to open boundary condition (OBC) and vice versa is\nanalyzed. Similar dynamics of both models are observed, but the quadrupole\ncorner states of the TQI makes the signatures more prominent. After the systems\ntransform from a cylinder or Mobius strip to OBC, the occupation of the corner\nstate of the TQI and the edge state of the CI exhibits steady-state behavior.\nThe steady-state values depend on the ramping rate of the configuration\ntransformation, manifesting a type of quantum memory effect. On the other hand,\noscillatory density ripples from the merging of edge states persist after the\nsystems transform from OBC to a cylinder or Mobius strip. If the final\nconfiguration is a cylinder, the density ripples are along the edges of the\ncylinder. In contrast, the density ripples can traverse the bulk after the\nsystems transform from OBC to a Mobius strip. The transformation of real-space\ntopology thus can be inferred from the dynamical signatures of the topological\nedge states.",
        "positive": "Quantum-limited shot noise in graphene: We calculate the mode-dependent transmission probability of massless Dirac\nfermions through an ideal strip of graphene (length L, width W, no impurities\nor defects), to obtain the conductance and shot noise as a function of Fermi\nenergy. We find that the minimum conductivity of order e^2/h at the Dirac point\n(when the electron and hole excitations are degenerate) is associated with a\nmaximum of the Fano factor (the ratio of noise power and mean current). For\nshort and wide graphene strips the Fano factor at the Dirac point equals 1/3,\nthree times smaller than for a Poisson process. This is the same value as for a\ndisordered metal, which is remarkable since the classical dynamics of the Dirac\nfermions is ballistic."
    },
    {
        "anchor": "Resonant x-ray diffraction from chiral electric-polarization structures: Heterostructures of PbTiO$_3$/SrTiO$_3$ superlattices have shown the\nformation of \"polar vortices\", in which a continuous rotation of ferroelectric\npolarization spontaneously forms. Recently, Shafer {\\it{et al.}} [Proc.\\ Natl.\\\nAcad.\\ Sci.\\ (PNAS) {\\bf{115}}, 915 (2018)] reported strong {\\it{non-magnetic}}\ncircular dichroism (CD) in resonant soft x-ray diffraction at the Ti $L_3$ edge\nfrom such superlattices. The authors ascribe the CD to the chiral rotation of a\npolar vector. However, a polar vector is invisible to the parity-even\nelectric-dipole transition which governs absorption in the soft x-ray region. A\nrealistic, non-magnetic explanation of the observed effect is found in\nTempleton-Templeton scattering. Following this route, the origin of the CD in\nBragg diffraction is shown by us to be the chiral array of charge quadrupole\nmoments that forms in these heterostructures. While there is no charge\nquadrupole moment in the spherically symmetric $3d^0$ valence state of\nTi$^{4+}$, the excited state $2p_{3/2}3d(t_{2g})$ at the Ti $L_3$ resonance is\nknown to have a quadrupole moment. Our expressions for intensities of satellite\nBragg spots in resonance-enhanced diffraction of circularly polarized x-rays,\nincluding their harmonic content, account for all observations reported by\nShafer {\\it{et al.}} We predict both intensities of Bragg spots for the second\nharmonic of a chiral superlattice and circular polarization created from\nunpolarized x-rays, in order that our successful explanation of existing\ndiffraction data can be further scrutinized through renewed experimental\ninvestigations. The increased understanding of chiral dipole arrangements could\nopen the door to switchable optical polarization.",
        "positive": "Electronic properties and quantum transports in functionalized graphene\n  Sierpinski carpet fractals: Recent progress in controllable functionalization of graphene surfaces\nenables the experimental realization of complex functionalized graphene\nnanostructures, such as Sierpinski carpet (SC) fractals. Herein, we model the\nSC fractals formed by hydrogen and fluorine functionalized patterns on graphene\nsurfaces, namely, H-SC and F-SC, respectively. We then reveal their electronic\nproperties and quantum transport features. From calculated results of the total\nand local density of state, we find that states in H-SC and F-SC have two\ncharacteristics: (i) low-energy states inside about |E/t|<1 (with t as the\nnear-neighbor hopping) are localized inside free graphene regions due to the\ninsulating properties of functionalized graphene regions, and (ii) high-energy\nstates in F-SC have two special energy ranges including -2.3<E/t<-1.9 with\nlocalized holes only inside free graphene areas and 3<E/t<3.7 with localized\nelectrons only inside fluorinated graphene areas. The two characteristics are\nfurther verified by the real-space distributions of normalized probability\ndensity. We analyze the fractal dimension of their quantum conductance spectra\nand find that conductance fluctuations in these structures follow the Hausdorff\ndimension. We calculate their optical conductivity and find that several\nadditional conductivity peaks appear in high energy ranges due to the adsorbed\nH or F atoms."
    },
    {
        "anchor": "Second-harmonic voltage responce for the magnetic Weyl semimetal\n  Co$_3$Sn$_2$S$_2$: We experimentally investigate longitudinal and transverse second-harmonic\nvoltage response to ac electrical current for a magnetic Weyl semimetal\nCo$_3$Sn$_2$S$_2$. In contrast to the previously observed Berry-curvature\ninduced non-linear Hall effect for non-magnetic Weyl and Dirac semimetals, the\nsecond-harmonic transverse voltage demonstrates sophisticated interplay of\ndifferent effects for Co$_3$Sn$_2$S$_2$. In high magnetic fields, it is of\nSeebeck-like square-B law, while the low-field behavior is found to be linear\nand sensitive to the direction of sample magnetization. The latter can be\nexpected both for the non-linear Hall effect and for the surface state\ncontribution to the Seebeck effect in Weyl semimetals. Thus, thermoelectric\neffects are significant in Co$_3$Sn$_2$S$_2$, unlike non-magnetic Weyl and\nDirac materials.",
        "positive": "Cooper pair splitting efficiency in the hybrid three-terminal quantum\n  dot: Nanodevices consisting of a quantum dot tunnel coupled to one superconducting\nand two normal electrodes may serve as a source of entangled electrons. As a\nresult of crossed Andreev reflection the Cooper pair of s-wave character may be\nsplit into two electrons and each of them goes into a distinct normal\nelectrode, preserving entanglement. Efficiency of the process depends on the\nspecific system and is tunable by electric means. Our calculations show that in\nthe studied device this efficiency may attain values as large as $80 \\%$."
    },
    {
        "anchor": "Single-Particle Excitations Generated by Voltage Pulses: We analyze properties of excitations due to voltage pulses applied to a 1D\nnoninteracting electron gas, assuming that the integral of the voltage over\ntime is equal to the unit of flux. We show that the average charge transfer due\nto such pulses does not depend on the pulse shape. For pulses with a Lorentzian\nprofile, we prove the single-particle nature of the electron and the hole\nexcitations.",
        "positive": "The quantum group, Harper equation and the structure of Bloch\n  eigenstates on a honeycomb lattice: The tight-binding model of quantum particles on a honeycomb lattice is\ninvestigated in the presence of homogeneous magnetic field. Provided the\nmagnetic flux per unit hexagon is rational of the elementary flux, the\none-particle Hamiltonian is expressed in terms of the generators of the quantum\ngroup $U_q(sl_2)$. Employing the functional representation of the quantum group\n$U_q(sl_2)$ the Harper equation is rewritten as a systems of two coupled\nfunctional equations in the complex plane. For the special values of\nquasi-momentum the entangled system admits solutions in terms of polynomials.\nThe system is shown to exhibit certain symmetry allowing to resolve the\nentanglement, and basic single equation determining the eigenvalues and\neigenstates (polynomials) is obtained. Equations specifying locations of the\nroots of polynomials in the complex plane are found. Employing numerical\nanalysis the roots of polynomials corresponding to different eigenstates are\nsolved out and the diagrams exhibiting the ordered structure of one-particle\neigenstates are depicted."
    },
    {
        "anchor": "Spin and Orbital Splitting in Ferromagnetic Contacted Single Wall Carbon\n  Nanotube Devices: We observed the coulomb blockade phenomena in ferromagnetic contacting single\nwall semiconducting carbon nanotube devices. No obvious Coulomb peaks shift was\nobserved with existing only the Zeeman splitting at 4K. Combining with other\neffects, the ferromagnetic leads prevent the orbital spin states splitting with\nmagnetic field up to 2 Tesla at 4K. With increasing magnetic field further,\nboth positive or negative coulomb peaks shift slopes are observed associating\nwith clockwise and anticlockwise orbital state splitting. The strongly\nsuppressed/enhanced of the conductance has been observed associating with the\nmagnetic field induced orbital states splitting/converging.",
        "positive": "Possible mechanisms of electronic phase separation in oxide interfaces: LaAlO3/SrTiO3 ad LaTiO3/SrTiO3 interfaces are known to host a strongly\ninhomogeneous (nearly) two-dimensional electron gas (2DEG). In this work we\npresent three unconventional electronic mechanisms of electronic phase\nseparation (EPS) in a 2DEG as a possible source of inhomogeneity in oxide\ninterfaces. Common to all three mechanisms is the dependence of some\n(interaction) potential on the 2DEG's density. We first consider a mechanism\nresulting from a sizable density-dependent Rashba spin-orbit coupling. Next, we\npoint out that an EPS may also occur in the case of a density-dependent\nsuperconducting pairing interaction. Finally, we show that the confinement of\nthe 2DEG to the interface by a density-dependent, self-consistent electrostatic\npotential can by itself cause an EPS."
    },
    {
        "anchor": "The honeycomb lattice with multi-orbital structure: topological and\n  quantum anomalous Hall insulators with large gaps: We construct a minimal four-band model for the two-dimensional (2D)\ntopological insulators and quantum anomalous Hall insulators based on the\n$p_x$- and $p_y$-orbital bands in the honeycomb lattice. The multiorbital\nstructure allows the atomic spin-orbit coupling which lifts the degeneracy\nbetween two sets of on-site Kramers doublets $j_z=\\pm\\frac{3}{2}$ and\n$j_z=\\pm\\frac{1}{2}$. Because of the orbital angular momentum structure of\nBloch-wave states at $\\Gamma$ and $K(K^\\prime)$ points, topological gaps are\nequal to the atomic spin-orbit coupling strengths, which are much larger than\nthose based on the mechanism of the $s$-$p$ band inversion. In the weak and\nintermediate regime of spin-orbit coupling strength, topological gaps are the\nglobal gap. The energy spectra and eigen wave functions are solved analytically\nbased on Clifford algebra. The competition among spin-orbit coupling $\\lambda$,\nsublattice asymmetry $m$ and the N\\'eel exchange field $n$ results in band\ncrossings at $\\Gamma$ and $K (K^\\prime)$ points, which leads to various\ntopological band structure transitions. The quantum anomalous Hall state is\nreached under the condition that three gap parameters $\\lambda$, $m$, and $n$\nsatisfy the triangle inequality. Flat bands also naturally arise which allow a\nlocal construction of eigenstates. The above mechanism is related to several\nclasses of solid state semiconducting materials.",
        "positive": "Phononic Crystals in Superfluid Thin-Film Helium: In recent years, nanomechanical oscillators in thin films of superfluid\nhelium have attracted attention in the field of optomechanics due to their\nexceptionally low mechanical dissipation and optical scattering. Mechanical\nexcitations in superfluid thin films - so-called third sound waves - can\ninteract with the optical mode of an optical microresonator by modulation of\nits effective refractive index enabling optomechanical coupling. Strong\nconfinement of third sound modes enhances their intrinsic mechanical\nnon-linearity paving the way for strong phonon-phonon interactions with\napplications in quantum optomechanics. Here, we realize a phononic crystal\ncavity confining third sound modes in a superfluid helium film to length scales\nclose to the third sound wavelength. A few nanometer thick superfluid film is\nself-assembled on top of a silicon nanobeam optical resonator. The periodic\npatterning of the silicon material creates a periodic modulation of the\nsuperfluid film leading to the formation of a phononic band gap. By engineering\nthe geometry of the silicon nanobeam, the phononic band gap allows the\nconfinement of a localized phononic mode."
    },
    {
        "anchor": "Electrical transport between epitaxial manganites and carbon nanotubes: The possibility of performing spintronics at the molecular level may be\nrealized in devices that combine fully spin polarized oxides such as manganites\nwith carbon nanotubes. However, it is not clear whether electrical transport\nbetween such different material systems is viable. Here we show that the room\ntemperature conductance of manganite-nanotube-manganite devices is only half\nthe value recorded in similar palladium-nanotube-palladium devices.\nInterestingly, the former shows a pseudogap in the conductivity below the\nrelatively high temperature of 200 K. Our results suggest the possibility of\nnew spintronics heterostructures that exploit fully spin polarized sources and\ndrains.",
        "positive": "Universality of Bias- and Temperature-induced Dephasing in Ballistic\n  Electronic Interferometers: We performed a transport measurement in a ballistic Aharonov-Bohm ring and a\nFabry-Perot type interferometer. In both cases we found that the interference\nsignal is reversed at a certain bias voltage and that the visibility decays\nexponentially as a function of temperature, being in a strong analogy with\nrecent reports on the electronic Mach-Zehnder interferometers. By analyzing the\ndata including those in the previous works, the energy scales that characterize\nthe dephasing are found to be dominantly dependent on the interferometer size,\nimplying the presence of a universal behavior in ballistic interferometers in\nboth linear and non-linear transport regimes."
    },
    {
        "anchor": "Hot-carrier transport and spin relaxation on the surface of topological\n  insulator: We study the charge and spin transport under high electric field (up to\nseveral kV/cm) on the surface of topological insulator Bi$_2$Se$_3$, where the\nelectron-surface optical phonon scattering dominates except at very low\ntemperature. Due to the spin mixing of conduction and valence bands, the\nelectric field not only accelerates electrons in each band, but also leads to\ninter-band precession. In the presence of the electric field, electrons can\ntransfer from the valence band to the conduction one via the inter-band\nprecession and inter-band electron-phonon scattering. The electron density in\neach band varies with the electric field linearly when the electric field is\nstrong. Due to the spin-momentum locking, a transverse spin polarization, with\nthe magnitude proportional to the momentum scattering time, is induced by the\nelectric field. The induced spin polarization depends on the electric field\nlinearly when the latter is small. Moreover, its magnitude is inversely\nproportional to the temperature and is insensitive to the electron density at\nhigh temperature. Our investigation also reveals that due to the large relative\nstatic dielectric constant, the Coulomb scattering is too weak to establish a\ndrifted Fermi distribution with a unified hot-electron temperature in the\nsteady state under the electric field. After turning off the electric field in\nthe steady state, the hot carriers cool down in a time scale of energy\nrelaxation which is very long (of the order of 100-1000 ps) while the spin\npolarization relaxes in a time scale of momentum scattering which is quite\nshort (of the order of 0.01-0.1 ps).",
        "positive": "Spin-momentum locking from topological quantum chemistry: applications\n  to multifold fermions: In spin-orbit coupled crystals, symmetries can protect multifold degeneracies\nwith large Chern numbers and Brillouin zone spanning topological surface\nstates. In this work, we explore the extent to which the nontrivial topology of\nchiral multifold fermions impacts the spin texture of bulk states. To do so, we\nformulate a definition of spin-momentum locking in terms of reduced density\nmatrices. Using tools from the theory of topological quantum chemistry, we show\nhow the reduced density matrix can be determined from the knowledge of the\nbasis orbitals and band representation forming the multifold fermion. We show\nhow on-site spin orbit coupling, crystal field splitting, and Wyckoff position\nmultiplicity compete to determine the spin texture of states near chiral\nfermions. We compute the spin texture of multifold fermions in several\nrepresentative examples from space groups $P432$ (207) and $P2_13$ (198). We\nshow that the winding number of the spin around the Fermi surface can take many\ndifferent integer values, from zero all the way to $\\pm 7$. Finally, we\nconclude by showing how to apply our theory to real materials using the example\nof PtGa in space group $P2_13$."
    },
    {
        "anchor": "Casimir effect due to a single boundary as a manifestation of the Weyl\n  problem: The Casimir self-energy of a boundary is ultraviolet-divergent. In many cases\nthe divergences can be eliminated by methods such as zeta-function\nregularization or through physical arguments (ultraviolet transparency of the\nboundary would provide a cutoff). Using the example of a massless scalar field\ntheory with a single Dirichlet boundary we explore the relationship between\nsuch approaches, with the goal of better understanding the origin of the\ndivergences. We are guided by the insight due to Dowker and Kennedy (1978) and\nDeutsch and Candelas (1979), that the divergences represent measurable effects\nthat can be interpreted with the aid of the theory of the asymptotic\ndistribution of eigenvalues of the Laplacian discussed by Weyl. In many cases\nthe Casimir self-energy is the sum of cutoff-dependent (Weyl) terms having\ngeometrical origin, and an \"intrinsic\" term that is independent of the cutoff.\nThe Weyl terms make a measurable contribution to the physical situation even\nwhen regularization methods succeed in isolating the intrinsic part.\nRegularization methods fail when the Weyl terms and intrinsic parts of the\nCasimir effect cannot be clearly separated. Specifically, we demonstrate that\nthe Casimir self-energy of a smooth boundary in two dimensions is a sum of two\nWeyl terms (exhibiting quadratic and logarithmic cutoff dependence), a\ngeometrical term that is independent of cutoff, and a non-geometrical intrinsic\nterm. As by-products we resolve the puzzle of the divergent Casimir force on a\nring and correct the sign of the coefficient of linear tension of the Dirichlet\nline predicted in earlier treatments.",
        "positive": "Quantum shape effects and novel thermodynamic behaviors at nanoscale: Thermodynamic properties of confined systems depend on sizes of the\nconfinement domain due to quantum nature of particles. Here we show that shape\nalso enters as a control parameter on thermodynamic state functions. By\nconsidering specially designed confinement domains, we separate the influences\nof quantum size and shape effects from each other and demonstrate how shape\neffects alone modify Helmholtz free energy, entropy and internal energy of a\nconfined system. We propose an overlapped quantum boundary layer method to\nanalytically predict quantum shape effects without even solving Schr\\\"odinger\nequation or invoking any other mathematical tools. Thereby we reduce a\nthermodynamic problem into a simple geometric one and reveal the profound link\nbetween geometry and thermodynamics. We report also a torque due to quantum\nshape effects. Furthermore, we introduce isoformal, shape preserving, process\nwhich opens the possibility of a new generation of thermodynamic cycles\noperating at nanoscale with unique features."
    },
    {
        "anchor": "Interaction-Induced Strong Localization in Quantum Dots: We argue that Coulomb blockade phenomena are a useful probe of the cross-over\nto strong correlation in quantum dots. Through calculations at low density\nusing variational and diffusion quantum Monte Carlo (up to r_s ~ 55), we find\nthat the addition energy shows a clear progression from features associated\nwith shell structure to those caused by commensurability of a Wigner crystal.\nThis cross-over (which occurs near r_s ~ 20 for spin-polarized electrons) is,\nthen, a signature of interaction-driven localization. As the addition energy is\ndirectly measurable in Coulomb blockade conductance experiments, this provides\na direct probe of localization in the low density electron gas.",
        "positive": "Metastable phase in the quantum Hall ferromagnet: Time-dependent capacitance measurements reveal an unstable phase of electrons\nin gallium arsenide quantum well that occurs when two Landau levels with\nopposite spin are brought close to degeneracy by applying a gate voltage. This\nphase emerges below a critical temperature and displays a peculiar\nnon-equilibrium dynamical evolution. The relaxation dynamics is found to follow\na stretched exponential behavior and correlates with hysteresis loops observed\nby sweeping the magnetic field. These experiments indicate that metastable\nrandomly-distributed magnetic domains are involved in the relaxation process in\na way that is equivalently tunable by a change in gate voltage or temperature."
    },
    {
        "anchor": "Properties of graphene deposited on GaN nanowires: influence of nanowire\n  roughness, self-induced nanogating and defects: We present detailed Raman studies of graphene deposited on gallium nitride\nnanowires with different variations in height. Our results show that different\ndensity and height of nanowires being in contact with graphene impact graphene\nproperties like roughness, strain and carrier concentration as well as density\nand type of induced defects. Detailed analysis of Raman spectra of graphene\ndeposited on different nanowire substrates shows that bigger differences in\nnanowires height increase graphene strain, while higher number of nanowires in\ncontact with graphene locally reduce the strain. Moreover, the value of\ngraphene carrier concentration is found to be correlated with the density of\nnanowires in contact with graphene. Analysis of intensity ratios of Raman G, D\nand D' bands enable to trace how nanowire substrate impacts the defect\nconcentration and type. The lowest concentration of defects is observed for\ngraphene deposited on nanowires of the lowest density. Contact between graphene\nand densely arranged nanowires leads to a large density of vacancies. On the\nother hand, grain boundaries are the main type of defects in graphene on rarely\ndistributed nanowires. Our results also show modification of graphene carrier\nconcentration and strain by different types of defects present in graphene.",
        "positive": "Quasiclassical approach and spin-orbit coupling: We discuss the quasiclassical Green function method for a two-dimensional\nelectron gas in the presence of spin-orbit coupling, with emphasis on the\nmeaning of the $\\xi$-integration procedure. As an application of our approach,\nwe demonstrate how the spin-Hall conductivity, in the presence of spin-flip\nscattering, can be easily obtained from the spin-density continuity equation."
    },
    {
        "anchor": "Tellurene-a monolayer of tellurium from first-principles prediction: A two dimensional (2D) Group-VI Te monolayer, tellurene, is predicted by\nusing the first-principles calculations, which consists of planner\nfour-membered and chair-like six-membered rings arranged alternately in a 2D\nlattice. The phonon spectra calculations, combined with ab initio molecular\ndynamics (MD) simulations, demonstrate that tellurene is kinetically very\nstable. The tellurene shows a desirable direct band gap of 1.04 eV and its band\nstructure can be effectively tuned by strain. The effective mass calculations\nimply that tellurene should also exhibit a relatively high carrier mobility,\ne.g. compared with MoS2. The significant direct band gap and the high carrier\nmobility imply that tellurene is a very promising candidate for a new\ngeneration of nanoelectronic devices.",
        "positive": "Magnetic vortex dynamics in a 2D easy plane ferromagnet: In this thesis, we consider the dynamics of vortices in the easy plane\ninsulating ferromagnet in two dimensions. In addition to the quasiparticle\nexcitations, here spin waves or magnons, this magnetic system admits a family\nof vortex solutions carrying two topological invariants, the winding number or\nvorticity, and the polarization. A vortex is approximately described as a\nparticle moving about the system, endowed with an effective mass and acted upon\nby a variety of forces. Classically, the vortex has an inter-vortex potential\nenergy giving a Coulomb-like force (attractive or repulsive depending on the\nrelative vortex vorticity), and a gyrotropic force, behaving as a self-induced\nLorentz force, whose direction depends on both topological indices. Expanding\nsemiclassically about a many-vortex solution, the vortices are quantized by\nconsidering the scattered magnon states, giving a zero point energy correction\nand a many-vortex mass tensor. The vortices cannot be described as independent\nparticles--that is, there are off-diagonal mass terms, such as 1/2 Mij vi vj,\nthat are non-negligible. This thesis examines the full vortex dynamics in\nfurther detail by evaluating the Feynman-Vernon influence functional, which\ndescribes the evolution of the vortex density matrix after the magnon modes\nhave been traced out. In addition to the set of forces already known, we find\nnew damping forces acting both longitudinally and transversely to the vortex\nmotion. The vortex motion within a collective cannot be entirely separated:\nthere are damping forces acting on one vortex due to the motion of another. The\neffective damping forces have memory effects: they depend not only on the\ncurrent motion of the vortex collection but also on the motion history."
    },
    {
        "anchor": "Low-Frequency 1/f Noise in MoS2 Thin-Film Transistors: Comparison of\n  Single and Multilayer Structures: We report on the transport and low-frequency noise measurements of MoS2\nthin-film transistors with \"thin\" (2-3 atomic layers) and \"thick\" (15-18 atomic\nlayers) channels. The back-gated transistors made with the relatively thick\nMoS2 channels have advantages of the higher electron mobility and lower noise\nlevel. The normalized noise spectral density of the low-frequency 1/f noise in\n\"thick\" MoS2 transistors is of the same level as that in graphene. The MoS2\ntransistors with the atomically thin channels have substantially higher noise\nlevels. It was established that, unlike in graphene devices, the noise\ncharacteristics of MoS2 transistors with \"thick\" channels (15-18 atomic planes)\ncould be described by the McWhorter model. Our results indicate that the\nchannel thickness optimization is crucial for practical applications of MoS2\nthin-film transistors.",
        "positive": "Finger-gate manipulated quantum transport in a semiconductor narrow\n  constriction with spin-orbit interactions and Zeeman effect: The authors investigate quantum transport in a narrow constriction fabricated\nby narrow band gap semiconductor materials with spin-orbit (SO) couplings. We\nconsider the Rashba-Dresselhaus (RD) spin-orbit interactions (SOIs) and the\nZeeman effect induced by an in-plane magnetic field along the transport\ndirection. The interplay of the RD-SOI and the Zeeman effect may induce a\nSOI-Zeeman gap and influence the transport properties. We demonstrate that an\nattractive scattering potential may induce electron-like quasi-bound-state\nfeature and manifest the RD-SOI-Zeeman induced Fano line-shape in conductance.\nFurthermore, a repulsive scattering potential may induce hole-like\nquasi-bound-state feature on the subband top of the lower spin branch."
    },
    {
        "anchor": "Quantitative comparison of magnon transport experiments in\n  three-terminal YIG/Pt nanostructures acquired via dc and ac detection\n  techniques: All-electrical generation and detection of pure spin currents is a promising\nway towards controlling the diffusive magnon transport in magnetically ordered\ninsulators. We quantitatively compare two measurement schemes, which allow to\nmeasure the magnon spin transport in a three-terminal device based on a yttrium\niron garnet thin film. We demonstrate that the dc charge current method based\non the current reversal technique and the ac charge current method utilizing\nfirst and second harmonic lock-in detection can both efficiently distinguish\nbetween electrically and thermally injected magnons. In addition, both\nmeasurement schemes allow to investigate the modulation of magnon transport\ninduced by an additional dc charge current applied to the center modulator\nstrip. However, while at low modulator charge current both schemes yield\nidentical results, we find clear differences above a certain threshold current.\nThis difference originates from nonlinear effects of the modulator current on\nthe magnon conductance.",
        "positive": "Large spin relaxation anisotropy and valley-Zeeman spin-orbit coupling\n  in WSe2/Gr/hBN heterostructures: Large spin-orbital proximity effects have been predicted in graphene\ninterfaced with a transition metal dichalcogenide layer. Whereas clear evidence\nfor an enhanced spin-orbit coupling has been found at large carrier densities,\nthe type of spin-orbit coupling and its relaxation mechanism remained unknown.\nWe show for the first time an increased spin-orbit coupling close to the charge\nneutrality point in graphene, where topological states are expected to appear.\nSingle layer graphene encapsulated between the transition metal dichalcogenide\nWSe$_2$ and hBN is found to exhibit exceptional quality with mobilities as high\nas 100000 cm^2/V/s. At the same time clear weak anti-localization indicates\nstrong spin-orbit coupling and a large spin relaxation anisotropy due to the\npresence of a dominating symmetric spin-orbit coupling is found. Doping\ndependent measurements show that the spin relaxation of the in-plane spins is\nlargely dominated by a valley-Zeeman spin-orbit coupling and that the intrinsic\nspin-orbit coupling plays a minor role in spin relaxation. The strong\nspin-valley coupling opens new possibilities in exploring spin and valley\ndegree of freedom in graphene with the realization of new concepts in spin\nmanipulation."
    },
    {
        "anchor": "Ultrafast energy relaxation of quantum dot-generated 2D hot electrons: Through a series of transverse magnetic focusing experiments, we show that\nhot electrons in a two-dimensional electron gas system undergo an ultrafast\nrelaxation when generated by a quantum dot (QD) instead of a quantum point\ncontact (QPC). We find here that QPC hot electrons were well described by the\nnon-interacting Fermi gas model for excitations up to 1.5 meV above the Fermi\nlevel of 7.44 meV, whereas QD hot electrons exhibited an energy loss quadratic\nto the excitation. The energy relaxation was a sizeable fraction of the tested\nexcitations, up to about 55%. With the proposal that the hot electrons are\nrelaxed by the QD immediately after emission, we present a toy model in which a\ncapacitive coupling between the QD and its leads results in a finite, ultrafast\nenergy relaxation.",
        "positive": "Quantum Hall Effect in a Graphene p-n Junction: We report on the fabrication and transport studies of a single-layer graphene\np-n junction. Carrier type and density in two adjacent regions are individually\ncontrolled by electrostatic gating using a local top gate and a global back\ngate. A functionalized Al203 oxide that adheres to graphene and does not\nsignificantly affect its electronic properties is described. Measurements in\nthe quantum Hall regime reveal new plateaus of two-terminal conductance across\nthe junction at 1 and 3/2 times the quantum of conductance, e2/h, consistent\nwith theory."
    },
    {
        "anchor": "Skyrmion magnetic structure of an ordered FePt monolayer deposited on\n  Pt(111): The effect of the Dzyaloshinsky-Moriya interaction on the magnetic structure\nof an ordered FePt monolayer deposited on Pt (111) surface has been\ninvestigated. In the ground state, the pronounced anisotropic geometry of the\nFePt layer with alternating Fe and Pt chains gives rise to a helimagnetic\nstructure with a strong difference in the helicity period along the chains and\nperpendicular to them. In the presence of an external magnetic field, the\nregion of stable Skyrmion magnetic structures in the $B-T$ phase diagram has\nbeen demonstrated via Monte Carlo simulations using the parameters obtained\nwithin first-principles electronic structure calculations. The present study\ndemonstrates clearly that the ratio of the exchange coupling parameters J/D for\na deposited magnetic film - being of central importance for the formation of\nSkyrmions - can be manipulated by growing an overlayer of 2-dimensional (2D)\ncompounds with the atoms carrying spontaneous magnetic moments separated by the\natoms of non-magnetic elements.",
        "positive": "I-band-like non-dispersive inter-shell interaction induced Raman lines\n  in the D band region of double-walled carbon nanotubes: Non-dispersive, inter-layer interaction induced Raman peaks (I bands) -- in\nthe region of the D band -- have been observed recently for bilayer graphene,\nwhen the two layers were rotated with respect to each other. Here, similar\nobservations for double-walled carbon nanotubes (DWCNTs) are theoretically\npredicted. The prediction is based on double resonance theory, involving\nnon-zone-centered phonons, and the effect of disorder is replaced by\ninteraction between the two tubes."
    },
    {
        "anchor": "Symmetry dictated universal helicity redistribution of Dirac fermions in\n  transport: Helicity is a fundamental property of Dirac fermions. Yet, the general rule\nof how it changes in transport is still lacking. We uncover, theoretically, the\nuniversal spinor state transformation and consequently helicity redistribution\nrule in two cases of transport through potentials of electrostatic and mass\ntypes, respectively. The former is dictated by Lorentz boost and its complex\ncounterpart in Klein tunneling regime, which establishes miraculously a unified\nyet latent connection between helicity, Klein tunneling, and Lorentz boost. The\nlatter is governed by an abstract rotation group we construct, which reduces to\nSO(2) when acting on the plane of effective mass and momentum. They generate\ninvariant submanifolds, i.e., leaves, that foliate the Hilbert space of Dirac\nspinors. Our results provide a basis for unified understanding of helicity\ntransport, and may open a new window for exotic helicity-based physics and\napplications in mesoscopic systems.",
        "positive": "Large spin-Hall effect in Si at room temperature: Silicon's weak intrinsic spin-orbit coupling and centrosymmetric crystal\nstructure are a critical bottleneck to the development of Si spintronics,\nbecause they lead to an insignificant spin-Hall effect (spin current\ngeneration) and inverse spin-Hall effect (spin current detection). Here, we\nundertake current, magnetic field, crystallography dependent magnetoresistance\nand magneto thermal transport measurements to study the spin transport behavior\nin freestanding Si thin films. We observe a large spin-Hall magnetoresistance\nin both p-Si and n-Si at room temperature and it is an order of magnitude\nlarger than that of Pt. One explanation of the unexpectedly large and efficient\nspin-Hall effect is spin-phonon coupling instead of spin-orbit coupling. The\nmacroscopic origin of the spin-phonon coupling can be large strain gradients\nthat can exist in the freestanding Si films. This discovery in a light, earth\nabundant and centrosymmetric material opens a new path of strain engineering to\nachieve spin dependent properties in technologically highly-developed\nmaterials."
    },
    {
        "anchor": "Superlattice platform for chiral superconductivity with tuneable and\n  high Chern numbers: Finding concrete realizations for topologically nontrivial chiral\nsuperconductivity has been a long-standing goal in quantum matter research.\nHere we propose a route to a systematic realization of chiral superconductivity\nwith nonzero Chern numbers. This goal can be achieved in a nanomagnet lattice\ndeposited on top of a spin-orbit coupled two-dimensional electron gas (2DEG)\nwith proximity s-wave superconductivity. The proposed structure can be regarded\nas a universal platform for chiral superconductivity supporting a large variety\nof topological phases. The topological state of the system can be electrically\ncontrolled by, for example, tuning the density of the 2DEG.",
        "positive": "Localization Length from Single-Particle Properties in Disordered\n  Electronic Systems: This preprint has been withdrawn as crucial errors have been discovered in\nthe papers it has referred to. It is now superseded by cond-mat/9807391."
    },
    {
        "anchor": "Transport through an impurity tunnel coupled to a Si/SiGe quantum dot: Achieving controllable coupling of dopants in silicon is crucial for\noperating donor-based qubit devices, but it is difficult because of the small\nsize of donor-bound electron wavefunctions. Here we report the characterization\nof a quantum dot coupled to a localized electronic state, and we present\nevidence of controllable coupling between the quantum dot and the localized\nstate. A set of measurements of transport through this device enable the\ndetermination of the most likely location of the localized state, consistent\nwith an electronically active impurity in the quantum well near the edge of the\nquantum dot. The experiments we report are consistent with a gate-voltage\ncontrollable tunnel coupling, which is an important building block for hybrid\ndonor and gate-defined quantum dot devices.",
        "positive": "Self-aligned graphene field-effect transistors with polyethyleneimine\n  doped source/drain access regions: We report a method of fabricating self-aligned, top-gated graphene\nfield-effect transistors (GFETs) employing polyethyleneimine spin-on-doped\nsource/drain access regions, resulting in a 2X reduction of access resistance\nand a 2.5X improvement in device electrical characteristics, over undoped\ndevices. The GFETs on Si/SiO$_2$ substrates have high carrier mobilities of up\nto 6,300 cm$^2$/Vs. Self-aligned spin-on-doping is applicable to GFETs on\narbitrary substrates, as demonstrated by a 3X enhancement in performance for\nGFETs on insulating quartz substrates, which are better suited for radio\nfrequency applications."
    },
    {
        "anchor": "Magnetically Defined Qubits on 3D Topological Insulators: We explore potentials that break time-reversal symmetry to confine the\nsurface states of 3D topological insulators into quantum wires and quantum\ndots. A magnetic domain wall on a ferromagnet insulator cap layer provides\ninterfacial states predicted to show the quantum anomalous Hall effect (QAHE).\nHere we show that confinement can also occur at magnetic domain\nheterostructures, with states extended in the inner domain, as well as\ninterfacial QAHE states at the surrounding domain walls. The proposed geometry\nallows the isolation of the wire and dot from spurious circumventing surface\nstates. For the quantum dots we find that highly spin-polarized quantized QAHE\nstates at the dot edge constitute a promising candidate for quantum computing\nqubits.",
        "positive": "Spin-Wave versus Joule Heating in Spin-Hall-Effect/Spin-Transfer-Torque\n  Driven Cr/Heusler/Pt Waveguides: We present a time-resolved study of the DC-current driven magnetization\ndynamics in a microstructured Cr/Heusler/Pt waveguide by means of Brillouin\nlight scattering. A reduction of the effective spin-wave damping via the\nspin-transfer-torque effect leads to a strong increase in the magnon density.\nThis is accompanied by a decrease of the spin-wave frequencies. By evaluating\nthe time scales of these effects, the origin of this frequency shift can be\nidentified. However, recently, we found that the experimental setup partially\ninfluences the decay of the spin-wave intensity after the current pulse is\nswitched off. Thus, further investigations on the presented effect are needed\nto allow for a more detailed analysis. For this reason, we need to withdraw the\nmanuscript at this point and might publish an updated version later."
    },
    {
        "anchor": "Index-antiguiding in narrow-ridge GaN-based laser diodes investigated by\n  measurements of the current-dependent gain and index spectra and by\n  self-consistent simulation: The threshold current density of narrow (1.5 {\\mu}m) ridge-waveguide InGaN\nmulti-quantum-well laser diodes, as well as the shape of their lateral\nfar-field patterns, strongly depend on the etch depth of the ridge waveguide.\nBoth effects can be attributed to strong index-antiguiding. A value of the\nantiguiding factor R = 10 is experimentally determined near threshold by\nmeasurements of the current-dependent gain and refractive index spectra. The\ndevice performances are simulated self-consistently solving the\nSchr\\\"odinger-Poisson equations and the equations for charge transport and\nwaveguiding. Assuming a carrier-induced index change which matches the\nexperimentally determined antiguiding factor, both the measured high threshold\ncurrent and the shape of the far-field pattern of lasers with shallow ridges\ncan be reproduced theoretically.",
        "positive": "Dissipation in Open Two-Level Systems: Perturbation Theory and Polaron\n  Transformation: We compare standard perturbation theory with the polaron transformation for\nnon-linear transport of electrons through a two-level system. For weak\nelectron-phonon coupling and large bias, there is good agreement between both\napproaches. This regime has recently been explored in experiments in double\nquantum dots."
    },
    {
        "anchor": "Rectifying full-counting statistics in a spin Seebeck engine: We investigate the rectification and negative differential effects of\nfull-counting statistics of conjugate thermal spin transport in a spin Seebeck\nengine. The engine is made by an electron/magnon interface diode driven by a\ntemperature bias, of which the scaled cumulant generating function is\nformulated in the framework of nonequilibrium Green's function. The strongly\nfluctuating interfacial electron density of states induced by quantum dot is\nresponsible for these intriguing properties. This work is relevant for\ndesigning efficient spin caloritronic engine and can broaden our view in\nnonequilibrium thermodynamics and the nonlinear phenomenon in quantum transport\nsystem.",
        "positive": "Effect of contacts on spin lifetime measurements in graphene: Injection, transmission, and detection of spins in a conducting channel are\nthe basic ingredients of spintronic devices. Long spin lifetimes during transit\nare an important ingredient in realizing this technology. An attractive\nplatform for this purpose is graphene, which has high mobilities and low\nspin-orbit coupling. Unfortunately, measured spin lifetimes are orders of\nmagnitude smaller than theoretically expected. A source of spin loss is the\nresistance mismatch between the ferromagnetic electrodes and graphene. While\nthis has been studied numerically, here we provide a closed form expression for\nHanle spin precession which is the standard method of measuring spin lifetimes.\nThis allows for a detailed characterization of the nonlocal spin valve device."
    },
    {
        "anchor": "Carrier Plasmon Induced Nonlinear Band Gap Renormalization in\n  Two-Dimensional Semiconductors: In reduced-dimensional semiconductors, doping-induced carrier plasmons can\nstrongly couple with quasiparticle excitations, leading to a significant band\ngap renormalization. We develop a new plasmon-pole theory that efficiently and\naccurately capture this coupling. Using monolayer molybdenum disulfide (MoS2)\nas a prototype two-dimensional (2D) semiconductor, we reveal an enhanced band\ngap renormalization around 400 meV and an unusual nonlinear evolution of its\nband gap with doping. This 2D prediction significantly differs from the linear\nbehaviors that are common to one-dimensional structures. Our developed approach\nallows for a quantitative understanding of many-body interactions in general\ndoped 2D semiconductors and paves the way for novel band gap engineering\ntechniques.",
        "positive": "Winding vector: how to annihilate two Dirac points with the same charge: The merging or emergence of a pair of Dirac points may be classified\naccording to whether the winding numbers which characterize them are opposite\n($+-$ scenario) or identical ($++$ scenario). From the touching point between\ntwo parabolic bands (one of them can be flat), two Dirac points with the {\\it\nsame} winding number emerge under appropriate distortion (interaction, etc),\nfollowing the $++$ scenario. Under further distortion, these Dirac points merge\nfollowing the $+-$ scenario, that is corresponding to {\\it opposite} winding\nnumbers. This apparent contradiction is solved by the fact that the winding\nnumber is actually defined around a unit vector on the Bloch sphere and that\nthis vector rotates during the motion of the Dirac points. This is shown here\nwithin the simplest two-band lattice model (Mielke) exhibiting a flat band. We\nargue on several examples that the evolution between the two scenarios is\ngeneral."
    },
    {
        "anchor": "On exciton decoherence in quantum dots: The effects resulting due to dressing of an exciton with phonons are analysed\nas the source of unavoidable decoherence of orbital degrees of freedom in\nquantum dots. The dressing with longitudinal optical phonons results in\nenergetic shift of order of a few meV even of the ground state of exciton in a\nstate-of-the-art InAs/GaAs dot and the mediating role of longitudinal\nacoustical phonons is essential in this process. The characteristic time needed\nfor dressing of the exciton with optical phonons is of a picosecond order. That\ntime can be regarded as the lowest limit for decoherence for optically driven\nquantum gates employing self-assembled quantum dot structures.",
        "positive": "Anisotropy of the molecular magnet V$_{15}$ spin Hamiltonian detected by\n  high-field electron spin resonance: The molecular compound K$_6$[V$^{IV}_{15}$As$^{III}_6$O$_{42}$(H$_2$O)]\n$\\cdot$ 8H$_2$O, in short V$_{15}$, has shown important quantum effects such as\ncoherent spin oscillations. The details of the spin quantum dynamics depend on\nthe exact form of the spin Hamiltonian. In this study, we present a precise\nanalysis of the intramolecular interactions in V$_{15}$. To that purpose, we\nperformed high-field electron spin resonance measurements at 120 GHz and\nextracted the resonance fields as a function of crystal orientation and\ntemperature. The data are compared against simulations using exact\ndiagonalization to obtain the parameters of the molecular spin Hamiltonian."
    },
    {
        "anchor": "Correlated charge transport in bilinear tunnel junction arrays: We study theoretically the nature of correlations in space and time of the\ncurrent in a one-dimensional bilinear array of tunnel junctions in the normal\nconduction limit, using the kinetic Monte Carlo (KMC) method. The bilinear\narray consists of two parallel rows of tunnel junctions, capacitively coupled\nin a ladder configuration. The electrostatic potential landscape and the\ncharge-charge interaction length both depend on the circuit capacitances, which\nin turn influence transport and charge correlations in the array. We observe\nthe formation of stationary charge states when only one rail is voltage biased.\nWhen a symmetric bias is applied to both rails, the site at which the positive\nand negative charge carriers recombine can drift throughout the array. We also\ncalculate charge densities and auto- and cross-correlation functions.",
        "positive": "Mode Delocalization in Disordered Photonic Chern Insulator: In disordered two dimensional Chern insulators, a single bulk extended mode\nis predicted to exist per band, up to a critical disorder strength; all the\nother bulk modes are localized. This behavior contrasts strongly with\ntopologically trivial two-dimensional phases, whose modes all become localized\nin the presence of disorder. Using a tight-binding model of a realistic\nphotonic Chern insulator, we show that delocalized bulk eigenstates can be\nobserved in an experimentally realistic setting. This requires the selective\nuse of resonator losses to suppress topological edge states, and acquiring\nsufficiently large ensemble sizes using variable resonator detunings."
    },
    {
        "anchor": "Atomic resolution imaging at 2.5 GHz using near-field microwave\n  microscopy: Atomic resolution imaging is demonstrated using a hybrid scanning\ntunneling/near-field microwave microscope (microwave-STM). The microwave\nchannels of the microscope correspond to the resonant frequency and quality\nfactor of a coaxial microwave resonator, which is built in to the STM scan head\nand coupled to the probe tip. We find that when the tip-sample distance is\nwithin the tunneling regime, we obtain atomic resolution images using the\nmicrowave channels of the microwave-STM. We attribute the atomic contrast in\nthe microwave channels to GHz frequency current through the tip-sample tunnel\njunction. Images of the surfaces of HOPG and Au(111) are presented.",
        "positive": "Energy Spectra for Fractional Quantum Hall States: Fractional quantum Hall states (FQHS) with the filling factor nu = p/q of q <\n21 are examined and their energies are calculated. The classical Coulomb energy\nis evaluated among many electrons; that energy is linearly dependent on 1/nu.\nThe residual binding energies are also evaluated. The electron pair in nearest\nLandau-orbitals is more affected via Coulomb transition than an electron pair\nin non-nearest orbitals. Each nearest electron pair can transfer to some empty\norbital pair, but it cannot transfer to the other empty orbital pair because of\nconservation of momentum. Counting the numbers of the allowed and forbidden\ntransitions, the binding energies are evaluated for filling factors of 126\nfraction numbers. Gathering the classical Coulomb energy and the pair\ntransition energy, we obtain the spectrum of energy versus nu. This energy\nspectrum elucidates the precise confinement of Hall resistance at specific\nfractional filling factors."
    },
    {
        "anchor": "Study Of Surface Spin-Polarized Electron Accumulation In Topological\n  Insulators Using Scanning Tunneling Microscopy: The results of scanning tunneling microscopy experiments using iron-coated\ntungsten tips and current-carrying bismuth selenide ($Bi_2Se_3$) samples are\nreported. Asymmetry in tunneling currents with respect to the change in the\ndirection of bias currents through $Bi_2Se_3$ samples has been observed. It is\nargued that this asymmetry is the manifestation of surface spin-polarized\nelectron accumulation caused by the ninety-degree electron spin-momentum\nlocking in the topologically protected surface current mode. It is demonstrated\nthat the manifestation of surface spin-polarized electron accumulation is\nenhanced by tin doping of $Bi_2Se_3$ samples. Furthermore, the appearance of\nspin-dependent density of states in current carrying $Bi_2Se_3$ samples has\nalso been observed.",
        "positive": "Tunable magnetism on the lateral mesoscale by post-processing of Co/Pt\n  heterostructures: Controlling magnetic properties on the nm-scale is essential for basic\nresearch in micro-magnetism and spin-dependent transport, as well as for\nvarious applications such as magnetic recording, imaging and sensing. This has\nbeen accomplished to a very high degree by means of layered heterostructures in\nthe vertical dimension. Here we present a complementary approach that allows\nfor a controlled tuning of the magnetic properties of Co/Pt heterostructures on\nthe lateral mesoscale. By means of in-situ post-processing of Pt- and Co-based\nnano-stripes prepared by focused electron beam induced deposition (FEBID) we\nare able to locally tune their coercive field and remanent magnetization.\nWhereas single Co-FEBID nano-stripes show no hysteresis, we find hard-magnetic\nbehavior for post-processed Co/Pt nano-stripes with coercive fields up to 850\nOe. We attribute the observed effects to the locally controlled formation of\nthe CoPt L1$_{0}$ phase, whose presence has been revealed by transmission\nelectron microscopy."
    },
    {
        "anchor": "Material Challenges for Colloidal Quantum Nanostructures in Next\n  Generation Displays: The recent technological advancements have greatly improved the quality and\nresolution of displays. Yet, issues like full color gamut representation and\nlong lasting durability of the color emitters require further progression.\nColloidal quantum dots manifest an inherent narrow spectral emission with\noptical stability, combined with various chemical processability options which\nwill allow for their integration in display applications. Apart from their\nnumerous advantages, they also present unique opportunities for the next\ntechnological leaps in the field.",
        "positive": "Enhancement of the thermoelectric properties in bilayer graphene\n  structures induced by Fano resonances: Fano and hybrid resonances of bilayer graphene could be attractive for\nthermoelectric devices. The special profile presented by such resonances could\nsignificantly enhance the Seebeck coefficient and the power factor. In this\nwork, we study the thermoelectric properties of bilayer graphene single and\ndouble barrier structures. The charge carriers are described as massive chiral\nparticles through an effective Dirac-like Hamiltonian. The Hybrid matrix\nmethod, the Landauer-B\\\"{u}ttiker formalism and the Cutler-Mott formula are\nimplemented to obtain the transmission, transport and thermoelectric\nproperties, respectively. The Seebeck coefficient and the power factor are\nanalyzed for gapless and gapped single and double barriers. We find that in the\nenergy range where Fano resonances occur, the Seebeck coefficient attains\nvalues of tens of mV/K and the power factor reaches values of the order nW/K.\nHybrid resonances also sustain high values for the thermoelectric properties,\nhowever not as high as Fano resonances. We also find that despite the Fano and\nhybrid profiles are manifested in the conductance of gapped barrier structures,\nthe Seebeck coefficient and the power factor are systematically reduced as the\nbandgap gets larger. So, our findings indicate that bilayer graphene barrier\nstructures can be used to improve the response of thermoelectric devices."
    },
    {
        "anchor": "Z2 invariant protected bound states in topological insulators: We present an exact solution of a modifed Dirac equation for topological\ninsulator in the presence of a hole or vacancy to demonstrate that vacancies\nmay induce bound states in the band gap of topological insulators. They arise\ndue to the Z_2 classification of time-reversal invariant insulators, thus are\nalso topologically-protected like the edge states in the quantum spin Hall\neffect and the surface states in three-dimensional topological insulators.\nCoexistence of the in-gap bound states and the edge or surface states in\ntopological insulators suggests that imperfections may affect transport\nproperties of topological insulators via additional bound states near the\nsystem boundary.",
        "positive": "Detection of quantum interference without interference: Quantum interference is typically detected through the dependence of the\ninterference signal on certain parameters (path length, Aharonov-Bohm flux,\netc.), which can be varied in a controlled manner. The destruction of\ninterference by a which-path measurement is a paradigmatic manifestation of\nquantum effects. Here we report on a novel measurement protocol that realizes\ntwo objectives: (i) certifying that a measured signal is the result of\ninterference avoiding the need to vary parameters of the underlying\ninterferometer, and (ii) certifying that the interference signal at hand is of\nquantum nature. In particular, it yields a null outcome in the case of\nclassical interference. Our protocol comprises measurements of\ncross-correlations between the readings of which-path weakly coupled detectors\npositioned at the respective interferometer's arms and the current in one of\nthe interferometer's drains. We discuss its implementation with an\nexperimentally available platform: an electronic Mach-Zehnder interferometer\n(MZI) coupled electrostatically to \"detectors\" (quantum point contacts)."
    },
    {
        "anchor": "Design of a 4-electrode optical device for application of vector\n  electric fields to self-assembled quantum dot complexes: Self-assembled InAs quantum dots (QDs) are of great interest as components of\noptoelectronic devices that can operate at the quantum limit. The charge\nconfiguration, interdot coupling, and symmetry of complexes containing multiple\nQDs can all be tuned with applied electric fields, but the magnitude and angle\nof the electric field required to control each of these parameters depends on\nthe orientation of the QD complex. We present a 4-electrode device compatible\nwith optical excitation and emission that allows application of electric fields\nwith arbitrary magnitudes and angles relative to isolated QD complexes. We\ndemonstrate the electric field tunability of this device with numerical\nsimulations.",
        "positive": "Fractional Quantum Hall States in Ultracold Rapidly Rotating Dipolar\n  Fermi Gases: We demonstrate the experimental feasibility of incompressible fractional\nquantum Hall-like states in ultra-cold two dimensional rapidly rotating dipolar\nFermi gases. In particular, we argue that the state of the system at filling\nfraction $\\nu =1/3$ is well-described by the Laughlin wave function and find a\nsubstantial energy gap in the quasiparticle excitation spectrum. Dipolar gases,\ntherefore, appear as natural candidates of systems that allow to realize these\nvery interesting highly correlated states in future experiments."
    },
    {
        "anchor": "Phase diagrams of magnetopolariton gases: The magnetic field effect on phase transitions in electrically neutral\nbosonic systems is much less studied than those in fermionic systems, such as\nsuperconducting or ferromagnetic phase transitions. Nevertheless, composite\nbosons are strongly sensitive to magnetic fields: both their internal structure\nand motion as whole particles may be affected. A joint effort of ten\nlaboratories has been focused on studies of polariton lasers, where\nnon-equilibrium Bose-Einstein condensates of bosonic quasiparticles,\nexciton-polaritons, may appear or disappear under an effect of applied magnetic\nfields. Polariton lasers based on pillar or planar microcavities were excited\nboth optically and electrically. In all cases a pronounced dependence of the\nonset to lasing on the magnetic field has been observed. For the sake of\ncomparison, photon lasing (lasing by an electron-hole plasma) in the presence\nof a magnetic field has been studied on the same samples as polariton lasing.\nThe threshold to photon lasing is essentially governed by the excitonic Mott\ntransition which appears to be sensitive to magnetic fields too. All the\nobserved experimental features are qualitatively described within a uniform\nmodel based on coupled diffusion equations for electrons, holes and excitons\nand the Gross-Pitaevskii equation for exciton-polariton condensates. Our\nresearch sheds more light on the physics of non-equilibrium Bose-Einstein\ncondensates and the results manifest high potentiality of polariton lasers for\nspin-based quantum logic applications.",
        "positive": "Transmission through a quantum dot molecule embedded in an Aharonov-Bohm\n  interferometer: We study theoretically the transmission through a quantum dot molecule\nembedded in the arms of an Aharonov-Bohm four quantum dot ring threaded by a\nmagnetic flux. The tunable molecular coupling provides a transmission pathway\nbetween the interferometer arms in addition to those along the arms. From a\ndecomposition of the transmission in terms of contributions from paths, we show\nthat antiresonances in the transmission arise from the interference of the\nself-energy along different paths and that application of a magnetic flux can\nproduce the suppression of such antiresonances. The occurrence of a period of\ntwice the quantum of flux arises to the opening of transmission pathway through\nthe dot molecule. Two different connections of the device to the leads are\nconsidered and their spectra of conductance are compared as a function of the\ntunable parameters of the model."
    },
    {
        "anchor": "2D condensate of electrons and holes in ultrathin MoTe$_2$ photocells: The electron-hole liquid, which features a macroscopic population of\ncorrelated electrons and holes, may offer a path to room temperature\nsemiconductor devices that harness collective electronic phenomena. We report\non the gas-to-liquid phase transition of electrons and holes in ultrathin\nmolybdenum ditelluride photocells revealed through multi-parameter dynamic\nphotoresponse microscopy (MPDPM). By combining rich visualization with\ncomprehensive analysis of very large data sets acquired through MPDPM, we find\nthat ultrafast laser excitation at a graphene-MoTe$_2$-graphene interface leads\nto the abrupt formation of ring-like spatial patterns in the photocurrent\nresponse as a function of increasing optical power at T = 297 K. These\npatterns, together with extreme sublinear power dependence and picosecond-scale\nphotocurrent dynamics, provide strong evidence for the formation of a\ntwo-dimensional electron-hole condensate.",
        "positive": "Observation of normal-force-independent superlubricity in mesoscopic\n  graphite contacts: We investigate the dependence of friction forces on normal load in\nincommensurate micrometer size contacts between atomically smooth\nsingle-crystal graphite surfaces under ambient conditions. Our experimental\nresults show that these contacts exhibit superlubricity (super-low friction),\nwhich is robust against the application of normal load. The measured friction\ncoefficients are essentially zero and independent of the external normal load\nup to a pressure of 1.67 MPa. The observation of load-independent\nsuperlubricity in micro-scale contacts is a promising result for numerous\npractical applications."
    },
    {
        "anchor": "Performance of the coupled cluster singles and doubles method on\n  two-dimensional quantum dots: An implementation of the coupled-cluster single- and double excitations\n(CCSD) method on two-dimensional quantum dots is presented. Advantages and\nlimitations are studied through comparison with other high accuracy approaches\nfor two to eight confined electrons. The possibility to effectively use a very\nlarge basis set is found to be an important advantage compared to full\nconfiguration interaction implementations. For the two to eight electron ground\nstates, with a confinement strength close to what is used in experiments, the\nerror in the energy introduced by truncating triple excitations and beyond is\nshown to be on the same level or less than the differences in energy given by\ntwo different Quantum Monte Carlo methods. Convergence of the iterative\nsolution of the coupled cluster equations is, for some cases, found for\nsurprisingly weak confinement strengths even when starting from a\nnon-interacting basis. The limit where the missing triple and higher\nexcitations become relevant is investigated through comparison with full\nConfiguration Interaction results.",
        "positive": "Observation of squeezed Chern insulator in an acoustic fractal lattice: Topological insulators are a new phase of matter with the distinctive\ncharacteristics of an insulating bulk and conducting edge states. Recent\ntheories indicate there even exist topological edge states in the\nfractal-dimensional lattices, which are fundamentally different from the\ncurrent studies that rely on the integer dimensions. Here, we propose and\nexperimentally demonstrate the squeezed Chern insulator in a\nfractal-dimensional acoustic lattice. First, through calculating the\ntopological invariant of our topological fractal system, we find the\ntopological phase diagram is squeezed by about 0.54 times, compared with that\nof the original Haldane model. Then by introducing synthetic gauge flux into an\nacoustic fractal lattice, we experimentally observe the one-way edge states\nthat are protected by a robust mobility gap within the squeezed topological\nregimes. Our work demonstrates the first example of acoustic topological\nfractal insulators and provides new directions for the advanced control of\nsound waves."
    },
    {
        "anchor": "Landau levels and Shubnikov-de Haas oscillations in monolayer transition\n  metal dichalcogenide semiconductors: We study the Landau level spectrum using a multi-band\n$\\mathbf{k}\\cdot\\mathbf{p}$ theory in monolayer transition metal dichalcogenide\nsemiconductors. We find that in a wide magnetic field range the Landau levels\ncan be characterized by a harmonic oscillator spectrum and a linear-in-magnetic\nfield term which describes the valley degeneracy breaking. The effect of the\nnon-parabolicity of the band-dispersion on the Landau level spectrum is also\ndiscussed. Motivated by recent magnetotransport experiments, we use the\nself-consistent Born approximation and the Kubo formalism to calculate the\nShubnikov de-Haas oscillations of the longitudinal conductivity. We investigate\nhow the doping level, the spin-splitting of the bands and the broken valley\ndegeneracy of the Landau levels affect the magnetoconductance oscillations.\nMotivated by recent experiments we consider monolayer MoS$_2$ and WSe$_2$ as\nconcrete examples and compare the results of numerical calculations and an\nanalytical formula which is valid in the semiclassical regime. Finally, we\nbriefly analyze the recent experimental results (Reference [18]) using the\ntheoretical approach we have developed.",
        "positive": "Quasi-particle behavior of composite fermions in the half-filled Landau\n  level: We calculate the effect of infrared fluctuations of the Chern-Simons gauge\nfield on the single-particle Green's function of composite fermions in the\nhalf-filled Landau level via higher-dimensional bosonization on a curved Fermi\nsurface. We find that composite fermions remain well-defined quasi-particles,\nwith an effective mass given by the mean-field value, but with anomalously\nlarge damping and a spectral function that contains considerable weight away\nfrom the quasi-particle peak."
    },
    {
        "anchor": "Single crystal growth, structure and electronic properties of metallic\n  delafossite PdRhO_{2}: We report growth of single crystals of the non-magnetic metallic delafossite\nPdRhO_{2}, comparing the results from three different methods. Complete\ncrystallographic data were obtained from single crystal X-ray diffraction, and\nelectronic structure calculations made using the refined structural parameters.\nFocused-ion beam microstructuring was used to prepare a sample for measurements\nof the in- and out-of-plane electrical resistivity, and the large observed\nanisotropy is qualitatively consistent with the cylindrical Fermi surface\npredicted by the calculations.",
        "positive": "Nanoscale control of LaAlO3/SrTiO3 metal-insulator transition using\n  ultra-low-voltage electron-beam lithography: We describe a method to control the insulator-metal transition at the\nLaAlO3/SrTiO3 interface using ultra-low-voltage electron beam lithography\n(ULV-EBL). Compared with previous reports that utilize conductive\natomic-force-microscope lithography (c-AFM), this approach can provide\ncomparable resolution (~10 nm) at write speeds (10 mm/s) that are up to 10,000x\nfaster than c-AFM. The writing technique is non-destructive and the conductive\nstate is reversible via prolonged exposure to air. Transport properties of\nrepresentative devices are measured at milli-Kelvin temperatures, where\nsuperconducting behavior is observed. We also demonstrate the ability to create\nconducting devices on graphene/LaAlO3/SrTiO3 heterostructures. The underlying\nmechanism is believed to be closely related to the same mechanism regulating\nc-AFM-based methods."
    },
    {
        "anchor": "Robust Type-II Weyl Semimetal Phase in Transition Metal Diphosphides\n  XP$_2$ (X = Mo, W): The recently discovered type-II Weyl points appear at the boundary between\nelectron and hole pockets. Type-II Weyl semimetals that host such points are\npredicted to exhibit a new type of chiral anomaly and possess thermodynamic\nproperties very different from their type-I counterparts. In this Letter, we\ndescribe the prediction of a type-II Weyl semimetal phase in the transition\nmetal diphosphides MoP$_2$ and WP$_2$. These materials are characterized by\nrelatively simple band structures with four pairs of type-II Weyl points.\nNeighboring Weyl points have the same chirality, which makes the predicted\ntopological phase robust with respect to small perturbations of the crystalline\nlattice. In addition, this peculiar arrangement of the Weyl points results in\nlong topological Fermi arcs, thus making them readily accessible in\nangle-resolved photoemission spectroscopy.",
        "positive": "Measurement of energy relaxation in quantum Hall edge states utilizing\n  quantum point contacts: We demonstrated a method to probe local electronic states and energy\nrelaxation in quantum Hall edge states utilizing quantum point contacts. We\nevaluated relaxation lengths in two cases; first, with electron tunneling, and\nsecond, only with energy exchange without tunneling between edge states. The\nresults were consistent with previous experiments and validated our method with\nquantum point contacts. We applied this method to measure the energy relaxation\nlength around a hotspot in quantum Hall regimes and revealed the possible\nshort-distance relaxation process to be the relaxation due to energy exchange\nbetween edge states without electron tunneling."
    },
    {
        "anchor": "Influence of shape of quantum dots on their far-infrared absorption: We investigate the effects of the shape of quantum dots on their far-infrared\nabsorption in an external magnetic field by a model calculation. We focus our\nattention on dots with a parabolic confinement potential deviating from the\ncommon circular symmetry, and dots having circular doughnut shape. For a\nconfinement where the generalized Kohn theorem does not hold we are able to\ninterprete the results in terms of a mixture of a center-of-mass mode and\ncollective modes reflecting an excitation of relative motion of the electrons.\nThe calculations are performed within the time-dependent Hartree approximation\nand the results are compared to available experimental results.",
        "positive": "Magnetic Field Probing of an SU(4) Kondo Resonance in a Single Atom\n  Transistor: Semiconductor nano-devices have been scaled to the level that transport can\nbe dominated by a single dopant atom. In the strong coupling case a Kondo\neffect is observed when one electron is bound to the atom. Here, we report on\nthe spin as well as orbital Kondo ground state. We experimentally as well than\ntheoretically show how we can tune a symmetry transition from a SU(4) ground\nstate, a many body state that forms a spin as well as orbital singlet by\nvirtual exchange with the leads, to a pure SU(2) orbital ground state, as a\nfunction of magnetic field. The small size and the s-like orbital symmetry of\nthe ground state of the dopant, make it a model system in which the magnetic\nfield only couples to the spin degree of freedom and allows for observation of\nthis SU(4) to SU(2) transition."
    },
    {
        "anchor": "Observation of magnetic domains in uniaxial magnets via small-angle\n  electron diffraction and Foucault imaging: Observation of magnetic domains is important in understanding the magnetic\nproperties of magnetic materials and devices. In this study, we report that the\nmagnetic domains of M-type hexaferrites with uniaxial anisotropy can be\nvisualized via small-angle electron diffraction and Foucault imaging. The\nposition of the diffraction pattern spots has the same period as that of\nmagnetic domains in a Sc-substituted hexaferrite\n(BaFe$_{12-x-\\delta}$Sc$_x$Mg$_\\delta$O$_{19}$). Conversely, the spots were\nobserved four times longer than the period of magnetic domains in hexaferrite\nwithout substitution (BaFe$_{12}$O$_{19}$), demonstrating the long-range order\nof the Bloch walls. When the specimen was tilted, the magnetic deflection\neffect, as well as the periodic spots of magnetic domains, occurred. Thus, we\nwere able to visualize the magnetic domains with different magnetization\ndirections and domain orientations by selecting deflection spots. The results\nindicate that the technique utilized in this study is useful in observing the\nmagnetic materials with uniaxial anisotropy.",
        "positive": "Landauer Theory, Inelastic Scattering and Electron Transport in\n  Molecular Wires: In this paper we address the topic of inelastic electron scattering in\nmesoscopic quantum transport. For systems where only elastic scattering is\npresent, Landauer theory provides an adequate description of transport that\nrelates the electronic current to single-particle transmission and reflection\nprobabilities. A formalism proposed recently by Bonca and Trugman facilitates\nthe calculation of the one-electron transmission and reflection probabilities\nfor inelastic processes in mesoscopic conductors connected to one-dimensional\nideal leads. Building on their work, we have developed a self-consistent\nprocedure for the evaluation of the non-equilibrium electron distributions in\nideal leads connecting such mesoscopic conductors to electron reservoirs at\nfinite temperatures and voltages. We evaluate the net electronic current\nflowing through the mesoscopic device by utilizing these non-equilibrium\ndistributions. Our approach is a generalization of Landauer theory that takes\naccount of the Pauli exclusion principle for the various competing elastic and\ninelastic processes while satisfying the requirement of particle conservation.\nAs an application we examine the influence of elastic and inelastic scattering\non conduction through a two site molecular wire with longitudinal phonons using\nthe Su-Schrieffer-Heeger model of electron-phonon coupling."
    },
    {
        "anchor": "Band strutures of hybrid graphene quantum dots with magnetic flux: We study the band structures of hybrid graphene quantum dots subject to a\nmagnetic flux and electrostatic potential. The system is consisting of a\ncircular single layer graphene surrounded by an infinite bilayer graphene. By\nsolving the Dirac equation we obtain the solution of the energy spectrum in two\nregions. For the valley $K$, it is found that the magnetic flux strongly acts\nby decreasing the gap and shifting energy levels away from zero radius with\nsome oscillations, which are note observed for null flux case. As for the\nvalley $K'$, the energy levels rapidly increase when the radius increases. A\nnumber of oscillations appeared that is strongly dependent on the values taken\nby the magnetic flux.",
        "positive": "Current crowding mediated large contact noise in graphene field-effect\n  transistors: The impact of the intrinsic time-dependent fluctuations in the electrical\nresistance at the graphene-metal interface or the contact noise, on the\nperformance of graphene field effect transistors, can be as adverse as the\ncontact resistance itself, but remains largely unexplored. Here we have\ninvestigated the contact noise in graphene field effect transistors of varying\ndevice geometry and contact configuration, with carrier mobility ranging from\n5,000 to 80,000$~$cm$^{2}$V$^{-1}$s$^{-1}$. Our phenomenological model for\ncontact noise due to current crowding in purely two dimensional conductors,\nconfirms that the contacts dominate the measured resistance noise in all\ngraphene field effect transistors in the two-probe or invasive four probe\nconfigurations, and surprisingly, also in nearly noninvasive four probe (Hall\nbar) configuration in the high mobility devices. The microscopic origin of\ncontact noise is directly linked to the fluctuating electrostatic environment\nof the metal-channel interface, which could be generic to two dimensional\nmaterial-based electronic devices."
    },
    {
        "anchor": "Spin-Pair Tunneling in Mn$_3$ Single-Molecule Magnet: We report spin-pair tunneling observed in Mn$_3$ single-molecule magnet,\nwhich is a crystal with 2D network of identical exchange coupling. We observed\na series of extra quantum tunnelings by the ac susceptibility measurements, and\ndemonstrated these are concerted tunnelings of two spins taking place from the\nsame initial state to the same final state simultaneously. The resonant field\nof spin-pair tunneling can be expressed as\n$H_z=lD/g\\mu_{0}\\mu_{B}+(n_{\\downarrow}-n_{\\uparrow})JS/2{g\\mu_{0}\\mu_{B}}$,\nand the splitting interval ($|J|S/{g\\mu_{0}\\mu_{B}}$) is half of that of the\nsingle-spin tunneling ($2|J|S/{g\\mu_{0}\\mu_{B}}$), which is analogous to the\nrelationship between the magnetic flux quantum in superconductor ($h/2e$) and\ncommon metal ($h/e$).",
        "positive": "Quantum Electronic Transport through a Precessing Spin: The conductance through a local nuclear spin precessing in a magnetic field\nis studied by using the equations-of-motion approach. The characteristics of\nthe conductance is determined by the tunneling matrix and the position of\nequilibrium chemical potential. We find that the spin flip coupling between the\nelectrons on the spin site and the leads produces the conductance oscillation.\nWhen the spin is precessing in the magnetic field at Larmor frequency\n($\\omega_{L}$), the conductance develops the oscillation with the frequency of\nboth $\\omega_{L}$ and 2$\\omega_{L}$ components, the relative spectrum weight of\nwhich can be tuned by the chemical potential and the spin flip coupling."
    },
    {
        "anchor": "Non-Abelian Geometric Phases and Conductance of Spin-3/2 Holes: Angular momentum $J=3/2$ holes in semiconductor heterostructures are showed\nto accumulate nonabelian geometric phases as a consequence of their motion. We\nprovide a general framework for analyzing such a system and compute conductance\noscillations for a simple ring geometry. We also analyze a figure-8 geometry\nwhich captures intrinsically nonabelian interference effects.",
        "positive": "Quantum Hall effect in polycrystalline graphene: The role of grain\n  boundaries: We use numerical simulations to predict peculiar magnetotransport\nfingerprints in polycrystalline graphene, driven by the presence of grain\nboundaries of varying size and orientation. The formation of Landau levels is\nshown to be restricted by the polycrystalline morphology, requiring the\nmagnetic length to be smaller than the average grain radius. The nature of\nlocalization is also found to be unusual, with strongly localized states at the\ncenter of Landau levels (including the usually highly robust zero-energy state)\nand extended electronic states lying between Landau levels. These extended\nstates percolate along the network of grain boundaries, resulting in a finite\nvalue for the bulk dissipative conductivity and suppression of the quantized\nHall conductance. Such breakdown of the quantum Hall regime provoked by\nextended structural defects is also illustrated through two-terminal\nLandauer-B\\\"uttiker conductance calculations, indicating how a single grain\nboundary induces cross-linking between edge states lying at opposite sides of a\nribbon geometry."
    },
    {
        "anchor": "The thermodynamic spin magnetization of strongly correlated 2d electrons\n  in a silicon inversion layer: A novel method invented to measure the minute thermodynamic spin\nmagnetization of dilute two dimensional fermions is applied to electrons in a\nsilicon inversion layer. Interplay between the ferromagnetic interaction and\ndisorder enhances the low temperature susceptibility up to 7.5 folds compared\nwith the Pauli susceptibility of non-interacting electrons. The magnetization\npeaks in the vicinity of the density where transition to strong localization\ntakes place. At the same density, the susceptibility becomes extremely close to\nthat of free spins (Curie susceptibility), indicating an almost perfect\ncompensation of the kinetic energy toll associated with spin polarization by\nthe energy gained from the ferromagnetic correlation. Yet, the balance favors a\nparamagnetic phase over spontaneous magnetization.",
        "positive": "Modulating near-field thermal transfer through temporal drivings: a\n  quantum many-body theory: The traditional approach to studying near-field thermal transfer is based on\nfluctuational electrodynamics. However, this approach may not be suitable for\nnonequilibrium states due to dynamic drivings. In our work, we introduce a\ntheoretical framework to describe the phenomenon of near-field heat transfer\nbetween two objects when subjected to periodic time modulations. We utilize the\nmachinery of nonequilibrium Green's function to derive general expressions for\nthe DC energy current in Floquet space. Furthermore, we also obtain the energy\ncurrent under the condition of small driving amplitude. The external drivings\ncreate a nonequilibrium state, which gives rise to various effects such as\nheat-transfer enhancement, heat-transfer suppression, and cooling. To\nillustrate these phenomena, we conduct numerical calculations on a system of\nCoulomb-coupled quantum dots, and specifically investigate the scenario of\nperiodically driving electronic reservoir. In our calculations, we employ the\n$G_0W_0$ approximation, which does not require self-consistent iteration and is\nsuitable for weak Coulomb interaction. Our theoretical formalism can be applied\nto study near-field energy transfer between two metallic plates under periodic\ntime modulations."
    },
    {
        "anchor": "Gate defined zero- and one-dimensional confinement in bilayer graphene: We report on the fabrication and measurement of nanoscale devices based on\nbilayer graphene sandwiched between hexagonal boron nitride bottom and top gate\ndielectrics. The top gates are patterned such that constrictions and islands\ncan be electrostatically induced by applying appropriate voltages to the gates.\nThe high quality of the devices becomes apparent from conductance quantization\nin the constrictions at low temperature. The islands exhibit clear Coulomb\nblockade and single-electron transport.",
        "positive": "Electrically-driven amplification of terahertz acoustic waves in\n  graphene: In graphene devices, the electronic drift velocity can easily exceed the\nspeed of sound in the material at moderate current biases. Under this\ncondition, the electronic system can efficiently amplify acoustic phonons,\nleading to the exponential growth of sound waves in the direction of the\ncarrier flow. Here, we demonstrate that such phonon amplification can\nsignificantly modify the electrical properties of graphene devices. We observe\na super-linear growth of the resistivity in the direction of the carrier flow\nwhen the drift velocity exceeds the speed of sound, causing up to a 7 times\nincrease over 8 micrometers. The resistance growth is observable for carrier\ndensities away from the Dirac point and is enhanced at cryogenic temperatures.\nThese observations are explained by a theoretical model for the\nelectrical-amplification of acoustic phonons, which reach frequencies up to 2.2\nterahertz with the nanoscale wavelength set by gate-tunable ~kF transitions\nacross the Fermi surface. These findings offer a route to high-frequency\non-chip sound generation and detection, which can be used to modulate and probe\nelectronic physics in van der Waals heterostructures in the terahertz frequency\nrange."
    },
    {
        "anchor": "Two-probe study of hot carriers in reduced graphene oxide: The energy relaxation of carriers in reduced graphene oxide thin films is\nstudied using optical pump-probe spectroscopy with two probes of different\ncolors. We measure the time difference between peaks of the carrier density at\neach probing energy by measuring a time-resolved differential transmission and\nfind that the carrier density at the lower probing energy peaks later than that\nat the higher probing energy. Also, we find that the peak time for the lower\nprobing energy shifts from about 92 to 37 fs after the higher probing energy\npeak as the carrier density is increased from 1.5E12 to 3E13 per square\ncentimeter, while no noticeable shift is observed in that for the higher\nprobing energy. Assuming the carriers rapidly thermalize after excitation, this\nindicates that the optical phonon emission time decreases from about 50 to\nabout 20 fs and the energy relaxation rate increases from 4 to 10 meV/fs. The\nobserved density dependence is inconsistent with the phonon bottleneck effect.",
        "positive": "Accessing nanotube bands via crossed electric and magnetic fields: We investigate the properties of conduction electrons in single-walled\narmchair carbon nanotubes in the presence of mutually orthogonal electric and\nmagnetic fields transverse to the tube's axis. We find that the fields give\nrise to an asymmetric dispersion in the right- and left-moving electrons along\nthe tube as well as a band-dependent interaction. We predict that such a\nnanotube system would exhibit spin-band-charge separation and a band-dependant\ntunneling density of states. We show that in the quantum dot limit, the fields\nserve to completely tune the quantum states of electrons added to the nanotube.\nFor each of the predicted effects, we provide examples and estimates that are\nrelevant to experiment."
    },
    {
        "anchor": "Magnetization Dynamics, Throughput and Energy Dissipation in a Universal\n  Multiferroic Nanomagnetic Logic Gate with Fan-in and Fan-out: The switching dynamics of a multiferroic nanomagnetic NAND gate with\nfan-in/fan-out is simulated by solving the Landau-Lifshitz-Gilbert (LLG)\nequation while neglecting thermal fluctuation effects. The gate and logic wires\nare implemented with dipole-coupled 2-phase (magnetostrictive/piezoelectric)\nmultiferroic elements that are clocked with electrostatic potentials of ~50 mV\napplied to the piezoelectric layer generating 10 MPa stress in the\nmagnetostrictive layers for switching. We show that a pipeline bit throughput\nrate of ~ 0.5 GHz is achievable with proper magnet layout and sinusoidal\nfour-phase clocking. The gate operation is completed in 2 ns with a latency of\n4 ns. The total (internal + external) energy dissipated for a single gate\noperation at this throughput rate is found to be only ~ 1000 kT in the gate and\n~3000 kT in the 12-magnet array comprising two input and two output wires for\nfan-in and fan-out. This makes it respectively 3 and 5 orders of magnitude more\nenergy-efficient than complementary-metal-oxide-semiconductor-transistor (CMOS)\nbased and spin-transfer-torque-driven nanomagnet based NAND gates. Finally, we\nshow that the dissipation in the external clocking circuit can always be\nreduced asymptotically to zero using increasingly slow adiabatic clocking, such\nas by designing the RC time constant to be 3 orders of magnitude smaller than\nthe clocking period. However, the internal dissipation in the device must\nremain and cannot be eliminated if we want to perform fault-tolerant classical\ncomputing.\n  Keywords: Nanomagnetic logic, multiferroics, straintronics and spintronics,\nLandau-Lifshitz-Gilbert equation.",
        "positive": "Non-equilibrium transport through a vertical quantum dot in the absence\n  of spin-flip energy relaxation: We investigate non-equilibrium transport in the absence of spin-flip energy\nrelaxation in a few-electron quantum dot artificial atom. Novel non-equilibrium\ntunneling processes involving high-spin states which cannot be excited from the\nground state because of spin-blockade, and other processes involving more than\ntwo charge states are observed. These processes cannot be explained by orthodox\nCoulomb blockade theory. The absence of effective spin relaxation induces\nconsiderable fluctuation of the spin, charge, and total energy of the quantum\ndot. Although these features are revealed clearly by pulse excitation\nmeasurements, they are also observed in conventional dc current characteristics\nof quantum dots."
    },
    {
        "anchor": "Approaching transform-limited photons from nanowire quantum dots excited\n  above-band: We demonstrate that, even when employing above-band excitation, photons\nemitted from semiconductor quantum dots can have linewidths that approach their\ntransform-limited values. This is accomplished by using quantum dots embedded\nin bottom-up photonic nanowires, an approach which mitigates several potential\nmechanisms that can result in linewidth broadening: (i) only a single quantum\ndot is present in each device, (ii) dot nucleation proceeds without the\nformation of a wetting layer, and (iii) the sidewalls of the photonic nanowire\nare comprised not of etched facets, but of epitaxially grown crystal planes.\nUsing these structures we achieve linewidths of 2x the transform limit,\nunprecedented for above-band excitation. We also demonstrate a highly nonlinear\ndependence of the linewidth on both excitation power and temperature which can\nbe described by an independent Boson model that considers both deformation and\npiezoelectric exciton-phonon coupling. We find that for sufficiently low\nexcitation powers and temperatures, the observed excess broadening is not\ndominated by phonon dephasing, a surprising result considering the high phonon\noccupation that occurs with above-band excitation.",
        "positive": "Non-equilibrium Thermal Resistance of Interfaces Between III-V Compounds: Interfacial thermal resistance has been often estimated and understood using\nthe Landauer formalism that assumes incident phonons with equilibrium\ndistribution. However, previous studies suggest that phonons are\nout-of-equilibrium near the interface because of the heat flow through the\nleads and the scattering of phonons by the interface. In this paper, we report\na systematic study on how vibrational spectra mismatch affects the degree of\nphonon non-equilibrium near an interface, how fast it is relaxed as the phonons\ndiffuse into a lead, and the overall interfacial thermal resistance from the\nnon-equilibrium phonons. Our discussion is based on the solution of the\nPeierls-Boltzmann transport equation with ab initio inputs for 36 interfaces\nbetween semi-infinite group-III (Al, Ga, In) and group-V (P, As, Sb) compound\nsemiconductor leads. The simulation reveals that the non-equilibrium phonons\ncause significant interfacial thermal resistance for all 36 interfaces, making\nthe overall interfacial thermal resistance two to three times larger than that\npredicted by the Landauer formalism. We observe a clear trend that the degree\nof phonon non-equilibrium near an interface and the interfacial thermal\nresistance from the non-equilibrium phonons increase as the mismatch of the\nDebye temperature of two lead materials increases. This contrasts with Landauer\nformalism's predictions, which show no correlation with the Debye temperature\nmismatch. The relaxation length of the phonon non-equilibrium varies\nsignificantly from 50nm to 1.5um depending on the combination of the lead\nmaterials. The relaxation length is proportional to the phonon mean free path\nof the corresponding lead material but also largely depends on the material in\nthe opposite lead. This suggests the relaxation length cannot be considered an\nintrinsic property of the corresponding lead material."
    },
    {
        "anchor": "Dynamically broken symmetry in periodically gated quantum dots: Charge\n  accumulation and dc-current: Time-dependent electron transport through a quantum dot and double quantum\ndot systems in the presence of polychromatic external periodic quantum dot\nenergy-level modulations is studied within the time evolution operator method\nfor a tight-binding Hamiltonian. Analytical relations for the dc-current\nflowing through the system and the charge accumulated on a quantum dot are\nobtained for the zero-temperature limit. It is shown that in the presence of\nperiodic perturbations the sideband peaks of the transmission are related to\ncombination frequencies of the applied modulations. For a double quantum dot\nsystem under the influence of polychromatic perturbations the quantum pump\neffect is studied in the absence of source-drain and static bias voltages. In\nthe presence of spatial symmetry the charge is pumped through the system due to\nbroken generalized parity symmetry.",
        "positive": "Tuning Spin Transport in a Graphene Antiferromagnetic Insulator: Long-distance spin transport through anti-ferromagnetic insulators (AFMIs) is\na long-standing goal of spintronics research. Unlike conventional spintronics\nsystems, monolayer graphene in quantum Hall regime (QH) offers an unprecedented\ntuneability of spin-polarization and charge carrier density in QH edge states.\nHere, using gate-controlled QH edges as spin-dependent injectors and detectors\nin an all-graphene electrical circuit, for the first time we demonstrate a\nselective tuning of ambipolar spin transport through graphene $\\nu$=0 AFMIs. By\nmodulating polarities of the excitation bias, magnetic fields, and charge\ncarriers that host opposite chiralities, we show that the difference between\nspin chemical potentials of adjacent edge channels in the spin-injector region\nis crucial in tuning spin-transport observed across graphene AFMI. We\ndemonstrate that non-local response vanishes upon reversing directions of the\nco-propagating edge channels when the spin-filters in our devices are no longer\nselective for a particular spin-polarization. Our results establish a versatile\nset of methods to tune pure spin transport via an anti-ferromagnetic media and\nopen a pathway to explore their applications for a broad field of\nantiferromagnetic spintronics research."
    },
    {
        "anchor": "Density of states of a dissipative quantum dot coupled to a quantum wire: We examine the local density of states of an impurity level or a quantum dot\ncoupled to a fractional quantum Hall edge, or to the end of a single\none-dimensional Luttinger-liquid lead. Effects of an Ohmic dissipative bath are\nalso taken into account. Using both analytical and numerical techniques we show\nthat, in general, the density of states exhibits power-law frequency dependence\nnear the Fermi energy. In a substantial region of the parameter space it simply\nreflects the behavior of the tunneling density of states at the end of a\nLuttinger-liquid, and is insensitive either to the value of the dot-lead\ninteraction or to the strength of dissipation; otherwise it depends on these\ncouplings too. This behavior should be contrasted with the thermodynamic\nproperties of the level, in particular, its occupancy, which were previously\nshown to depend on the various interactions in the system only through the\ncorresponding Fermi edge singularity exponent, and thus cannot display any\nLuttinger-liquid specific power-law. Hence, we can construct different models,\nsome with and some without interactions in the wire (but with equal Fermi edge\nsingularity exponents), which would have very different level densities of\nstates, although they all result in the same level population vs. energy\ncurves.",
        "positive": "Electrodynamic properties of graphene and their technological\n  applications: Graphene is a novel two-dimensional material with fascinating electrodynamic\nproperties like the ability to support collective electron oscillations\n(plasmons) accompanied by tight confinement of electromagnetic fields. Our goal\nis to explore light-matter interaction in graphene in the context of plasmonics\nand other technological applications but also to use graphene as a platform for\nstudying many body physics like the interaction between plasmons, phonons and\nother elementary excitations. Plasmons and plasmon-phonon interaction are\nanalyzed within the self-consistent linear response approximation. We\ndemonstrate that electron-phonon interaction leads to large plasmon damping\nwhen plasmon energy exceeds that of the optical phonon but also a peculiar\nmixing of plasmon and optical phonon polarizations. Plasmon-phonon coupling is\nstrongest when these two excitations have similar energy and momentum. We also\nanalyze properties of transverse electric plasmons in bilayer graphene. Finally\nwe show that thermally excited plasmons strongly mediate and enhance the near\nfield radiation transfer between two closely separated graphene sheets. We also\ndemonstrate that graphene can be used as a thermal emitter in the near field\nthermophotovoltaics leading to large efficiencies and power densities. Near\nfield heat transfer is analyzed withing the framework of fluctuational\nelectrodynamics."
    },
    {
        "anchor": "Topological frequency conversion in Weyl semimetals: We theoretically predict a new working principle for optical amplification,\nbased on Weyl semimetals: when a Weyl semimetal is suitably irradiated at two\nfrequencies, electrons close to the Weyl points convert energy between the\nfrequencies through the mechanism of topological frequency conversion from\n[Martin et al, PRX 7 041008 (2017)]. Each electron converts energy at a\nquantized rate given by an integer multiple of Planck's constant multiplied by\nthe product of the two frequencies. In simulations, we show that optimal, but\nfeasible band structures can support topological frequency conversion in the\n\"THz gap\" at intensities down to $ 2{\\rm W}/{\\rm mm^2}$; the gain from the\neffect can exceed the dissipative loss when the frequencies are larger than the\nrelaxation time of the system. Topological frequency conversion provides a new\nparadigm for optical amplification, and further extends Weyl semimetals'\npromise for technological applications.",
        "positive": "Free-electron Model for Mesoscopic Force Fluctuations in Nanowires: When two metal electrodes are separated, a nanometer sized wire (nanowire) is\nformed just before the contact breaks. The electrical conduction measured\nduring this retraction process shows signs of quantized conductance in units of\nG_0=2e^2/h. Recent experiments show that the force acting on the wire during\nseparation fluctuates, which has been interpreted as being due to atomic\nrearrangements. In this report we use a simple free electron model, for two\nsimple geometries, and show that the electronic contribution to the force\nfluctuations is comparable to the experimentally found values, about 2 nN."
    },
    {
        "anchor": "Observation of transition from escape dynamics to underdamped phase\n  diffusion in a Josephson junction: We have investigated the dynamics of underdamped Josephson junctions. In\naddition to the usual crossover between macroscopic quantum tunnelling and\nthermally activated (TA) behaviour we observe in our samples with relatively\nsmall Josephson coupling E_J, for the first time, the transition from TA\nbehaviour to underdamped phase diffusion. Above the crossover temperature the\nthreshold for switching into the finite voltage state becomes extremely sharp.\nWe propose a (T,E_J) phase-diagram with various regimes and show that for a\nproper description of it dissipation and level quantization in a metastable\nwell are crucial.",
        "positive": "Transition absorption as a mechanism of surface photoelectron emission\n  from metals: Transition absorption of electromagnetic field energy by an electron passing\nthrough a boundary between two media with different dielectric permittivities\nis considered both classically and quantum mechanically. It is shown that\ntransition absorption can make a substantial contribution to the process of\nelectron photoemission from metals due to the surface photoelectric effect."
    },
    {
        "anchor": "Random Lasing from Weakly Scattering Media: Universality in the Emission\n  Spectra from Pi-Conjugated Polymer Films: When films of Pi-conjugated polymers are optically excited above a certain\nthreshold intensity, then the emission spectrum acquires a multimode finely\nstructured shape, which depends on the position of the excitation spot. We\ndemonstrate that the power Fourier transform (PFT) of the emission spectrum\nexhibits a certain peak-like structure, which also depends on the excitation\nspot. Our intriguing observation is that averaging the individual PFTs does not\nlead to a structureless curve, but rather yields a series of distinct transform\npeaks. This suggests universality, namely that the underlying random resonators\nthat are responsible for the laser emission from the pi-conjugated polymer film\nare almost identical. We argue that the reason for such an universality is the\nlarge size of a typical resonator, which we determined from the PFT, as\ncompared to the emission wavelength, lambda. This fact is, in turn, a\nconsequence of the large light mean free path, l* approximately 10 lambda in\nthe polymer film. This contrasts previous observations of random lasing in\npowders, where l* approx. lambda. We develop a simple theory that explains the\npresence of peaks in the average PFT and predicts their shape. The results of\nthe theory agree quantitatively with the data.",
        "positive": "Topological classification of crystalline insulators through band\n  structure combinatorics: We present a method for efficiently enumerating all allowed, topologically\ndistinct, electronic band structures within a given crystal structure. The\nalgorithm applies to crystals with broken time-reversal, particle-hole, and\nchiral symmetries in any dimension. The presented results match the\nmathematical structure underlying the topological classification of these\ncrystals in terms of K-theory, and therefore elucidate this abstract\nmathematical framework from a simple combinatorial perspective. Using a\nstraightforward counting procedure, we classify the allowed topological phases\nin any possible two-dimensional crystal in class A. We also show how the same\nprocedure can be used to classify the allowed phases for any three-dimensional\nspace group. Employing these classifications, we study transitions between\ntopological phases within class A that are driven by band inversions at high\nsymmetry points in the first Brillouin zone. This enables us to list all\npossible types of phase transitions within a given crystal structure, and\nidentify whether or not they give rise to intermediate Weyl semimetallic\nphases."
    },
    {
        "anchor": "Transport through graphene double dots: We present Coulomb blockade measurements in a graphene double dot system. The\ncoupling of the dots to the leads and between the dots can be tuned by graphene\nin-plane gates. The coupling is a non-monotonic function of the gate voltage.\nUsing a purely capacitive model, we extract all relevant energy scales of the\ndouble dot system.",
        "positive": "Optical readout of charge and spin in a self-assembled quantum dot in a\n  strong magnetic field: We present a theory and experiment demonstrating optical readout of charge\nand spin in a single InAs/GaAs self-assembled quantum dot. By applying a\nmagnetic field we create the filling factor 2 quantum Hall singlet phase of the\ncharged exciton. Increasing or decreasing the magnetic field leads to\nelectronic spin-flip transitions and increasing spin polarization. The\nincreasing total spin of electrons appears as a manifold of closely spaced\nemission lines, while spin flips appear as discontinuities of emission lines.\nThe number of multiplets and discontinuities measures the number of carriers\nand their spin. We present a complete analysis of the emission spectrum of a\nsingle quantum dot with N=4 electrons and a single hole, calculated and\nmeasured in magnetic fields up to 23 Tesla."
    },
    {
        "anchor": "Stark-Effect Scattering in Rough Quantum Wells: A scattering mechanism stemming from the Stark-shift of energy levels by\nelectric fields in semiconductor quantum wells is identified. This scattering\nmechanism feeds off interface roughness and electric fields, and modifies the\nwell known 'sixth-power' law of electron mobility degradation. This work first\ntreats Stark-effect scattering in rough quantum wells as a perturbation for\nsmall electric fields, and then directly absorbs it into the Hamiltonian for\nlarge fields. The major result is the existence of a window of quantum well\nwidths for which the combined roughness scattering is minimum. Carrier\nscattering and mobility degradation in wide quantum wells are thus expected to\nbe equally severe as in narrow wells due to Stark-effect scattering in electric\nfields.",
        "positive": "Tuning Fano resonances by magnetic forces for electron transport through\n  a quantum wire side-coupled to a quantum ring: We consider electron transport in a quantum wire with a side-coupled quantum\nring in a two-dimensional model that accounts for a finite width of the\nchannels. We use the finite difference technique to solve the scattering\nproblem as well as to determine the ring-localized states of the energy\ncontinuum. The backscattering probability exhibits Fano peaks for magnetic\nfields for which a ring-localized states appear at the Fermi level. We find\nthat the width of the Fano resonances changes at high magnetic field. The width\nis increased (decreased) for resonant states with current circulation that\nproduce the magnetic dipole moment that is parallel (antiparallel) to the\nexternal magnetic field. We indicate that the opposite behavior of Fano\nresonances due to localized states with clockwise and counterclockwise currents\nresults from the magnetic forces which change the strength of their coupling to\nthe channel and modify the lifetime of localized states."
    },
    {
        "anchor": "Elastic deformations and Wigner-Weyl formalism in graphene: We discuss the tight-binding models of solid state physics with the $Z_2$\nsublattice symmetry in the presence of elastic deformations, and their\nimportant particular case -the tight binding model of graphene. In order to\ndescribe the dynamics of electronic quasiparticles we explore Wigner-Weyl\nformalism. It allows to calculate the two-point Green's function in the\npresence of both slowly varying external electromagnetic fields and the\ninhomogeneous modification of the hopping parameters resulted from the elastic\ndeformations. The developed formalism allows us to consider the influence of\nelastic deformations and the variations of magnetic field on the quantum Hall\neffect.",
        "positive": "Readout of parafermionic states by transport measurements: Recent experiments have demonstrated the possibility of inducing\nsuperconducting pairing into counterpropagating fractional quantum Hall edge\nmodes. This paves the way for the realization of localized parafermionic modes,\nnon-Abelian anyons that share fractional charges in a nonlocal way. We show\nthat, for a pair of isolated parafermions, this joint degree of freedom can be\nread by conductance measurements across standard metallic electrodes. We\npropose two complementary setups. We investigate first the transport through a\ngrounded superconductor hosting two interacting parafermions. In the low-energy\nlimit, its conductance peaks reveal their shared fractional charge yielding a\nthree-state telegraph noise for weak quasiparticle poisoning. We then examine\nthe two-terminal electron conductance of a blockaded fractional topological\nsuperconductor, which displays a characteristic $e/3$ periodicity of its\nzero-bias peaks in the deep topological regime, thus signalling the presence of\nparafermionic modes."
    },
    {
        "anchor": "The half-filled Landau level - composite fermions and dipoles: The composite-fermion approach as formulated in the fermion Chern-Simons\ntheory has been very successful in describing the physics of the lowest Landau\nlevel near Landau level filling factor 1/2. Recent work has emphasized the fact\nthat the true quasiparticles at these filling factors are electrically neutral\nand carry an electric dipole moment. In a previous work, we discussed at length\ntwo formulations in terms of dipolar quasiparticles. Here we briefly review one\napproach - termed electron-centered quasiparticles - and show how it can be\nextended from 1/2 to nearby filling factors where the quasiparticles carry both\nan electric dipole moment and an overall charge.",
        "positive": "A new type of optical biosensor from DNA wrapped semiconductor graphene\n  ribbons: Based on a model of the optical biosensors (Science 311, 508 (2006)) by\nwrapping a piece of double-stranded DNA around the surface of single-walled\ncarbon nanotubes (SWCNT), we propose a new design model of this sensor, in\nwhich the SWCNT is replaced by a semiconductor graphene ribbon (SGR). Using a\nsimple theory of exciton in SGRs, we investigated transition of DNA secondary\nstructure from the native, right-handed B form to the alternate, left-handed Z\nform. This structural phase transition of DNA is the working principle of this\noptical biosensor at the sub cellular level from DNA and semiconductor graphene\nribbons."
    },
    {
        "anchor": "Probing the charge of a quantum dot with a nanomechanical resonator: We have used the mechanical motion of a carbon nanotube (CNT) as a probe of\nthe average charge on a quantum dot. Variations of the resonance frequency and\nthe quality factor are determined by the change in average charge on the\nquantum dot during a mechanical oscillation. The average charge, in turn, is\ninfluenced by the gate voltage, the bias voltage, and the tunnel rates of the\nbarriers to the leads. At bias voltages that exceed the broadening due to\ntunnel coupling, the resonance frequency and quality factor show a double dip\nas a function of gate voltage. We find that increasing the current flowing\nthrough the CNT at the Coulomb peak does not increase the damping, but in fact\ndecreases damping. Using a model with energy-dependent tunnel rates, we obtain\nquantitative agreement between the experimental observations and the model. We\ntheoretically compare different contributions to the single-electron induced\nnonlinearity, and show that only one term is significant for both the Duffing\nparameter and the mode coupling parameter. We also present additional\nmeasurements which support the model we develop: Tuning the tunnel barriers of\nthe quantum dot to the leads gives a 200-fold decrease of the quality factor.\nSingle-electron tunneling through an excited state of the CNT quantum dot also\nchanges the average charge on the quantum dot, bringing about a decrease in the\nresonance frequency. In the Fabry-P\\'{e}rot regime, the absence of charge\nquantization results in a spring behaviour without resonance frequency dips,\nwhich could be used, for example, to probe the transition from quantized to\ncontinuous charge with a nanomechanical resonator.",
        "positive": "Sarin and Air Permeation Through a Nanoporous Graphene: Sarin gas is a dangerous chemical warfare agent (CWA). It is a nerve agent\ncapable of bringing a person to death in about 15 minutes. A lethal\nconcentration of sarin molecules in air is about 30 mg/m3. Experimental\nresearch on this gas requires very careful safety protocols for handling and\nstorage. Therefore, theoretical and computational studies on sarin gas are very\nwelcome and might provide important safe guides towards the management of this\nlethal substance. In this work, we investigated the interactions between sarin,\nair and nanoporous graphene, using tools of classical molecular dynamics\nsimulations. Aiming to cast some light in the possible sarin selective\nfiltration by graphene, we designed a bipartite simulation box with a porous\ngraphene nanosheet placed at the middle. Sarin and air molecules were initially\nplaced only on one side of the box so as to create an initial pressure towards\nthe passage of both to the other side. The box dimensions were chosen so that\nthe hole in the graphene was the only possible way through which sarin and air\nmolecules can get to the other side of the box. The number of molecules that\npassed through the hole in graphene was monitored during 10 ns of simulation\nand the results for different temperatures were compared. The results show\nthat, as far as the size of the holes are small, van der Waals forces between\ngraphene and the molecules play a significant role on keeping sarin near\ngraphene, at room temperature."
    },
    {
        "anchor": "Importance of quantum interference in molecular-scale devices: Electron transport is theoretically investigated in a molecular device made\nof anthracene molecule attached to the electrodes by thiol end groups in two\ndifferent configurations (para and meta, respectively). Molecular system is\ndescribed by a simple Huckel-like model (with non-orthogonal basis set of\natomic orbitals), while the coupling to the electrodes is treated through the\nuse of Newns-Anderson chemisorption theory (constant density of states within\nenergy bandwidth). Transport characteristics (current-voltage and\nconductance-voltage) are calculated from the transmission function in the\nstandard Landauer formulation. The essential question of quantum interference\nis discussed in detail. The results have shown a striking variation of\ntransport properties of the device depending on the character of molecular\nbinding to the electrodes.",
        "positive": "Quantum Hall Transitions in Field Induced Spin Density Wave Systems: Field Induced Spin Density Wave (FISDW) systems exhibit coexistence phases\nbetween well defined quantum Hall plateau phases with even integers 2N and 2N'.\nWe show that a disordered coexistence region accounts for the observed peaks in\nthe longitudinal resistivity as the field varies between plateaux. It also\nresults in a random spin mixing which yields two energy split extended states.\nThe longitudinal resistance is expected to show peaks witha temperature (T)\ndependent width proportional to the kappa's power of T. The peak width should\nsaturate below the non-nesting interlayer coupling of order 40 mK"
    },
    {
        "anchor": "Electric-Magnetic Duality and Topological Insulators: We work out the action of the SL(2,Z) electric-magnetic duality group for an\ninsulator with a non-trivial permittivity, permeability and theta-angle. This\ntheory has recently been proposed to be the correct low-energy effective action\nfor topological insulators. As applications, we give manifestly SL(2,Z)\ncovariant expressions for the Faraday rotation at orthogonal incidence at the\ninterface of two such materials, as well as for the induced magnetic and\nelectric charges, slightly clarifying the meaning of expressions previously\nderived in the literature. We also use electric-magnetic duality to find a\ngravitational dual for a strongly coupled version of this theory using the\nAdS/CFT correspondence.",
        "positive": "Crossover from Regular to Chaotic Behavior in the Conductance of\n  Periodic Quantum Chains: The conductance of a waveguide containing finite number of periodically\nplaced identical point-like impurities is investigated. It has been calculated\nas a function of both the impurity strength and the number of impurities using\nthe Landauer-B\\\"uttiker formula. In the case of few impurities the conductance\nis proportional to the number of the open channels $N$ of the empty waveguide\nand shows a regular staircase like behavior with step heights $\\approx 2e^2/h$.\nFor large number of impurities the influence of the band structure of the\ninfinite periodic chain can be observed and the conductance is approximately\nthe number of energy bands (smaller than $N$) times the universal constant\n$2e^2/h$. This lower value is reached exponentially with increasing number of\nimpurities. As the strength of the impurity is increased the system passes from\nintegrable to quantum-chaotic. The conductance, in units of $2e^2/h$, changes\nfrom $N$ corresponding to the empty waveguide to $\\sim N/2 $ corresponding to\nchaotic or disordered system. It turnes out, that the conductance can be\nexpressed as $(1-c/2)N$ where the parameter $0<c<1$ measures the chaoticity of\nthe system."
    },
    {
        "anchor": "Many-body effects in a quasi-one-dimensional electron gas: We have investigated electron transport in a quasi-one dimensional (quasi-1D)\nelectron gas as a function of the confinement potential. At a particular\npotential configuration, and electron concentration, the ground state of a 1D\nquantum wire splits into two rows to form an incipient Wigner lattice. It was\nfound that application of a transverse magnetic field can transform a\ndouble-row electron configuration into a single-row due to magnetic enhancement\nof the confinement potential. The movements of the energy levels have been\nmonitored under varying conditions of confinement potential and in-plane\nmagnetic field. It is also shown that when the confinement is weak, electron\noccupation drives a reordering of the levels such that the normal ground state\npasses through the higher levels. The results show that the levels can be\nmanipulated by utilising their different dependence on spatial confinement and\nelectron concentration, thus enhancing the understanding of many body\ninteractions in mesoscopic 1D quantum wires.",
        "positive": "Observation of Flat Frequency Bands at Open Edges and Antiphase Boundary\n  Seams in Topological Mechanical Metamaterials: Motivated by the recent theoretical studies on a two-dimensional (2D) chiral\nHamiltonian based on the Su-Schrieffer-Heeger chains, we experimentally and\ncomputationally demonstrate that topological flat frequency bands can occur at\nopen edges of 2D planar metamaterials and at antiphase boundary seams of\nring-shaped or tubular metamaterials. Specifically, using mechanical systems\nmade of magnetically coupled spinners, we reveal that the presence of the edge\nor seam bands that are flat in the entire projected reciprocal space follows\nthe predictions based on topological winding numbers. The edge-to-edge distance\nsensitively controls the flatness of the edge bands and the localization of\nexcitations. The analogue of the fractional charge state is also observed.\nPossible realizations of flat bands in a large class of metamaterials,\nincluding photonic crystals and electronic metamaterials, are discussed."
    },
    {
        "anchor": "Cotunneling through quantum dots coupled to magnetic leads: zero-bias\n  anomaly for non-collinear magnetic configurations: Cotunneling transport through quantum dots weakly coupled to non-collinearly\nmagnetized leads is analyzed theoretically by means of the real-time\ndiagrammatic technique. The electric current, dot occupations, and dot spin are\ncalculated in the Coulomb blockade regime and for arbitrary magnetic\nconfiguration of the system. It is shown that an effective exchange field\nexerted on the dot by ferromagnetic leads can significantly modify the\ntransport characteristics in non-collinear magnetic configurations, in\nparticular the zero-bias anomaly found recently for antiparallel configuration.\nFor asymmetric Anderson model, the exchange field gives rise to precession of\nthe dot spin, which leads to a nonmonotonic dependence of the differential\nconductance and tunnel magnetoresistance on the angle between magnetic moments\nof the leads. An enhanced differential conductance and negative TMR are found\nfor certain non-collinear configurations.",
        "positive": "Attractive and driven interaction in quantum dots: mechanisms for\n  geometric pumping: We analyze time-dependent transport through a quantum dot with\nelectron-electron interaction that is statically tunable to both repulsive and\nattractive regimes, or even dynamically driven. Motivated by the recent\nexperimental realization [Hamo et. al, Nature 535, 395 (2016)] of such a system\nin a static double quantum dot we compute the geometric pumping of charge in\nthe limit of weak tunneling, high temperature and slow driving. We analyze the\npumping responses for all pairs of driving parameters (gate voltage, bias\nvoltage, tunnel coupling, electron-electron interaction). We show that the\nresponses are analytically related when these different driving protocols are\ngoverned by the same pumping mechanism, which is characterized by effective\ndriving parameters that differ from the experimental ones. For static\nattractive interaction we find a characteristic pumping resonance despite the\n'attractive Coulomb blockade' that hinders stationary transport. Moreover, we\nidentify a pumping mechanism that is unique to driving of the interaction.\nFinally, although a single-dot model with orbital pseudo-spin describes most of\nthe physics of the mentioned experimental setup, it is crucial to account for\nthe additional (real-) spin degeneracies of the double dot and the associated\nelectron-hole symmetry breaking. This is necessary because the pumping response\nis more sensitive than DC transport measurements and detects this difference\nthrough pronounced qualitative effects."
    },
    {
        "anchor": "Frictionless flow in a binary polariton superfluid: We study the properties of a binary microcavity polariton superfluid\ncoherently injected by two lasers. The crossover from the supersonic to\nsubsonic regime, where motion is frictionless, is described by evaluating the\nBogoliubov spectra. We show that according to the Landau criteria, the coupling\nbetween the two components precludes the existence of superfluidity just for\none component but not for the other. By analysing the drag force exerted on a\ndefect, we give a recipe to experimentally address the crossover from the\nsupersonic to the subsonic regime.",
        "positive": "Correlated breakdown of carbon nanotubes in an ultra-high density\n  aligned array: We demonstrate that in a densely packed aligned array of single walled carbon\nnanotubes, the breakdown of one nanotube leads to a highly correlated breakdown\nof neighboring nanotubes, thereby producing a nano-fissure. We show that the\norigin of the correlation is the electrostatic field of the broken nanotubes\nthat produces locally inhomogeneous current and Joule heating distributions in\nthe neighboring intact nanotubes triggering their breakdowns in the vicinity of\nthe broken nanotubes. Our results suggest that the densely aligned array\nbehaves like a correlated solid."
    },
    {
        "anchor": "Magnetic dynamics with Weyl fermions: Transport of charge and valley degrees of freedom coupled to order-parameter\ndynamics in magnetic Weyl semimetals is studied in the framework of\nnonequilibrium thermodynamics. In addition to the established valley-related\ntransport anomalies that are rooted in band-structure topology, we construct\ndissipative couplings between the three dynamic constituents of the system\ndriven out of equilibrium by electromagnetic perturbations. We show how the\nvalley degree of freedom mediates an effective coupling between the charge and\nmagnetic sectors of the system, through a combination of the chiral anomaly, on\nthe electric side, and the Onsager-paired valley torque and pumping, on the\nmagnetic side. This work compliments previous studies of magnetic Weyl\nsemimetals by a more systematic analysis of collective dissipation. We discuss\nseveral concrete examples of the valley-mediated current-driven magnetic\ninstabilities and charge pumping, and extend the theory to the\nantiferromagnetic case.",
        "positive": "The Edge-State Theory of Integer-Quantum-Hall-Effect to Insulator\n  Transition: Direct transitions, driven by disorder, from several integral quantum Hall\nstates to an insulator have been observed in experiment. This finding is\nenigmatic in light of a theoretical phase diagram, based on rather general\nconsiderations, that predicts a sequence of transitions in which the integer\n$n$ characterizing the Hall conductivity is reduced successively by unity,\neventually going from $n=1$ into an insulator. In this work, we suggest that\nthe direct transition occurs because, in certain parameter regime, the edge\nstates of different Landau levels are strongly coupled and behave as a single\nedge state. It is indicated under what conditions successive transitions may be\nseen."
    },
    {
        "anchor": "Carbon nanotubes: Nonlinear high-Q resonators with strong coupling to\n  single-electron tunneling: Carbon nanotubes (CNTs) are nonlinear high-Q resonators with strong coupling\nto single-electron tunneling. We begin by describing several methods to detect\nthe flexural motion of a CNT resonator. Next, we illustrate how single-electron\ntunneling in quantum dot CNT resonators leads to sharp dips in the mechanical\nresonance frequency and significant damping. We discuss four different\ncontributions to the nonlinear oscillation of a CNT resonator: beam-like\nmechanical nonlinearity, nonlinearity due to gate-induced mechanical tension,\nelectrostatic nonlinearity, and nonlinearity due to single-electron tunneling,\nand provide quantitative estimates of their strengths. Finally, we show how the\nlarge response of the resonance frequency of a CNT resonator to a change in\ngate voltage or tension makes CNT resonators ideally suited for parametric\nexcitation and for studying the coupling between different mechanical modes.",
        "positive": "Enhancement of the electron-phonon scattering induced by intrinsic\n  surface plasmon-phonon polaritons: We investigate light-matter coupling in metallic crystals where plasmons\ncoexist with phonons exhibiting large oscillator strength. We demonstrate\ntheoretically that this coexistence can lead to strong light-matter\ninteractions without external resonators. When the frequencies of plasmons and\nphonons are comparable, hybridization of these collective matter modes occurs\nin the crystal. We show that the coupling of these modes to photonic degrees of\nfreedom gives rise to intrinsic surface plasmon-phonon polaritons, which offer\nthe unique possibility to control the phonon properties by tuning the electron\ndensity and the crystal thickness. In particular, dressed phonons with reduced\nfrequency and large wave vectors arise in the case of quasi-2D crystals, which\nleads to large enhancements of the electron-phonon scattering in the\nvibrational ultrastrong coupling regime. This suggests that photons can play a\nkey role in determining the quantum properties of certain materials. A\nnon-perturbative self-consistent Hamiltonian method is presented that is valid\nfor arbitrarily large coupling strengths."
    },
    {
        "anchor": "Effect of Holstein phonons on the optical conductivity of gapped\n  graphene: We study the optical conductivity of a doped graphene when a sublattice\nsymmetry breaking is occurred in the presence of the electron-phonon\ninteraction. Our study is based on the Kubo formula that is established upon\nthe retarded self-energy. We report new features of both the real and imaginary\nparts of the quasiparticle self-energy in the presence of a gap opening. We\nfind an analytical expression for the renormalized Fermi velocity of massive\nDirac Fermions over broad ranges of electron densities, gap values and the\nelectron-phonon coupling constants. Finally we conclude that the inclusion of\nthe renormalized Fermi energy and the band gap effects are indeed crucial to\nget reasonable feature for the optical conductivity.",
        "positive": "Influence of ZnTe based distributed Bragg reflectors on the yellow range\n  luminescence of self assembled CdTe QDs: The influence of a distributed Bragg reflector composed of ZnTe, MgTe, and\nMgSe superlattices on photoluminescence of self assembled CdTe quantum dots\n(QD) emitting in the yellow spectral range is investigated. In the case of QDs\ngrown on a distributed Bragg reflector the photoluminescence intensity is\nenhanced by more than one order of magnitude, whereas the single QD lines are\nbroadened as compared to the case of QDs grown on a ZnTe buffer. Structural and\nchemical analysis reveal an unintentional formation of a thin ZnSe layer\ninduced by the growth interruption needed for the deposition of the QDs sheet.\nSharp emission lines from individual quantum dots are recovered in the case of\na thicker ZnTe layer grown prior to the QDs. This indicates that growth\ninterruptions might be responsible for the QD emission line broadening."
    },
    {
        "anchor": "Nonequilibrium configuration interaction method for transport in\n  correlated quantum systems: We present a new approach to treat correlations in nonequilibrium quantum\nmany-particle system. The method is based on ideas of configuration interaction\ntheory of exact nonperturbative ground state electronic structure calculations.\nWe use superoperator techniques in Liouville-Fock space and represent the\nnonequilibrium density matrix as a linear combination of all possible\nnonequilibrium quasiparticle excitations built on the appropriate reference\nstate. As an example we consider the electron transport through the system with\nelectron-phonon interaction. The concept of embedding (buffer zones between the\nreservoirs and the correlated quantum system) is used to derive an exact master\nequation for the reduced density matrix. Using approximate (truncated)\nexpansion of the trial density matrix we obtain the linear system of equations\nfor two-quasiparticle amplitudes. Then we compute the steady-state current and\ncompare the result with other approaches. The current conserving property of\nthe method is proved.",
        "positive": "Topological superconductivity in Rashba semiconductors without a Zeeman\n  field: In this manuscript I present new hybrid devices based on multi-wire/channel\nRashba semiconductors, which harbor Majorana fermions (MFs) without a Zeeman\nfield. In contrast, magnetic fluxes, supercurrents or electric fields can be\nemployed, yielding an enhanced device manipulability. The generic topological\nphase diagram for two-nanowire/channel systems exhibits features of quantum\ncriticality and a rich interplay of phases with 0, 1 or 2 MFs per edge. The\nmost prominent and experimentally feasible implementation relies on the already\nexisting platforms of InAs-2DEG on top of a Josephson junction. Appropriate\ndesign of the latter device allows phases with 1 or 2 MFs, both detectable in\nzero-bias anomaly peaks with a single or double unit of conductance."
    },
    {
        "anchor": "Locking and Tracking Magnetic Resonance Spectra of NV- Center for\n  Real-time Magnetometry using a Differential Photon-Rate Meter: We describe a real-time data processing and frequency control method to track\npeaks in optically detected magnetic resonance of nitrogen-vacancy centers in\ndiamond. This procedure allows us to measure magnetic field continuously with\nsensitivity ~6 uT/Hz^{1/2} and to track resonances at sweep rates exceeding 110\nuT/s. We use a custom-built differential photon rate meter and active feedback\ncontrol to \"lock\" the microwave excitation frequency of the magnetic resonance.\nOur scheme covers a broad magnetic field range, limited by the frequency range\nof the microwave generator. This measurement procedure automates the processing\nof voltage pulse outputs from the photon counters, and it provides sensitivity\ncomparable to traditional photon counting methods",
        "positive": "Electrostatically induced phononic crystal: The possibility of realizing an electrostatically induced phononic crystal is\ninvestigated numerically in an acoustic waveguide based on a graphene sheet\nthat is suspended over periodically arrayed electrodes. The application of dc\nvoltage to these electrodes exerts electrostatic force on the graphene and this\nresults in the periodic formation of stress in the waveguide structure in a\nnon-invasive way, unlike the cases with mass loading and air holes. This\nnon-invasive scheme enables a bandgap, namely a phononic crystal, to be created\nin the waveguide that can be used to dynamically tune the acoustic transparency\nin the medium. Our approach will allow the dispersion relation to be locally\nmodified, thus modulating the temporal response of traveling acoustic phonon\nwaves. This novel phonon architecture is promising in terms of realizing the\nadvanced control of phonon dynamics such as waveform and dissipation\nengineering in the device."
    },
    {
        "anchor": "Orbital Kondo effect in carbon nanotubes: Progress in the fabrication of nanometer-scale electronic devices is opening\nnew opportunities to uncover the deepest aspects of the Kondo effect, one of\nthe paradigmatic phenomena in the physics of strongly correlated electrons.\nArtificial single-impurity Kondo systems have been realized in various\nnanostructures, including semiconductor quantum dots, carbon nanotubes and\nindividual molecules. The Kondo effect is usually regarded as a spin-related\nphenomenon, namely the coherent exchange of the spin between a localized state\nand a Fermi sea of electrons. In principle, however, the role of the spin could\nbe replaced by other degrees of freedom, such as an orbital quantum number.\nHere we demonstrate that the unique electronic structure of carbon nanotubes\nenables the observation of a purely orbital Kondo effect. We use a magnetic\nfield to tune spin-polarized states into orbital degeneracy and conclude that\nthe orbital quantum number is conserved during tunneling. When orbital and spin\ndegeneracies are simultaneously present, we observe a strongly enhanced Kondo\neffect, with a multiple splitting of the Kondo resonance at finite field and\npredicted to obey a so-called SU(4) symmetry.",
        "positive": "High cooperativity coupling of electron-spin ensembles to\n  superconducting cavities: Electron spins in solids are promising candidates for quantum memories for\nsuperconducting qubits because they can have long coherence times, large\ncollective couplings, and many quantum bits can be encoded into the spin-waves\nof a single ensemble. We demonstrate the coupling of electron spin ensembles to\na superconducting transmission-line resonator at coupling strengths greatly\nexceeding the cavity decay rate and comparable to spin linewidth. We also use\nthe enhanced coupling afforded by the small cross-section of the transmission\nline to perform broadband spectroscopy of ruby at millikelvin temperatures at\nlow powers. In addition, we observe hyperfine structure in diamond P1 centers\nand time domain saturation-relaxation of the spins."
    },
    {
        "anchor": "Short Ballistic Josephson Coupling in Planar Graphene Junctions with\n  Inhomogeneous Carrier Doping: We report on short ballistic (SB) Josephson coupling in junctions embedded in\na planar heterostructure of graphene. Ballistic Josephson coupling is confirmed\nby the Fabry-Perot-type interference of the junction critical current $I_c$. An\nexceptionally large $I_cR_N$ product close to $2\\Delta_0/e$ ($R_N$;\nnormal-state junction resistance, $\\Delta_0$ ; zero-temperature superconducting\nenergy gap) is an indication of SB strong Josephson coupling. $I_c$ shows a\ntemperature dependence inconsistent with the conventional short-junction-like\nbehavior; $I_c(T)$ curves deviate systematically from the standard\nKulik-Omel'yanchuk prediction. We argue that this feature stems from the planar\nnature of graphene junction, which is susceptible to the effects of\ninhomogeneous carrier doping as well in graphene near the superconducting\ncontacts.",
        "positive": "Random Matrices and Supersymmetry in Disordered Systems: It is described how one comes to the Wigner-Dyson random matrix theory (RMT)\nstarting from a model of a disordered metal. The lectures start with a\nhistorical introduction where basic ideas of the RMT and theory of disordered\nmetals are reviewed. This part is followed by an introduction into\nsupermathematics (mathematics operating with both commuting and anticommuting\nvariables). The main ideas of the supersymmetry method are given and basic\nformulae are derived. As an example, level-level correlations and fluctuations\nof amplitudes of wave functions are discussed. It is shown how one can both\nobtain known formulae of the RMT and go beyond. In the last part some recent\nprogress in the further development of the method and possible perspectives are\ndiscussed."
    },
    {
        "anchor": "Spin relaxation of two-dimensional holes in strained asymmetric SiGe\n  quantum wells: We analyze spin splitting of the two-dimensional hole spectrum in strained\nasymmetric SiGe quantum wells (QWs). Based on the Luttinger Hamiltonian, we\nobtain expressions for the spin-splitting parameters up to the third order in\nthe in-plane hole wavevector. The biaxial strain of SiGe QWs is found to be a\nkey parameter that controls spin splitting. Application to SiGe field-effect\ntransistor structures indicates that typical spin splitting at room temperature\nvaries from a few tenth of meV in the case of Si QW channels to several meV for\nthe Ge counterparts, and can be modified efficiently by gate-controlled\nvariation of the perpendicular confining electric field. The analysis also\nshows that for sufficiently asymmetric QWs, spin relaxation is due mainly to\nthe spin-splitting related D'yakonov-Perel' mechanism. In strained Si QWs, our\nestimation shows that the hole spin relaxation time can be on the order of a\nhundred picoseconds at room temperature, suggesting that such structures are\nsuitable for p-type spin transistor applications as well.",
        "positive": "Side gate tunable Josephson junctions at the LaAlO$_3$/SrTiO$_3$\n  interface: Novel physical phenomena arising at the interface of complex oxide\nheterostructures offer exciting opportunities for the development of future\nelectronic devices. Using the prototypical LaAlO$_3$/SrTiO$_3$ interface as a\nmodel system, we employ a single-step lithographic process to realize gate\ntunable Josephson junctions through a combination of lateral confinement and\nlocal side gating. The action of the side gates is found to be comparable to\nthat of a local back gate, constituting a robust and efficient way to control\nthe properties of the interface at the nanoscale. We demonstrate that the side\ngates enable reliable tuning of both the normal-state resistance and the\ncritical (Josephson) current of the constrictions. The conductance and\nJosephson current show mesoscopic fluctuations as a function of the applied\nside gate voltage, and the analysis of their amplitude enables the extraction\nof the phase coherence and thermal lengths. Finally, we realize a\nsuperconducting quantum interference device in which the critical currents of\neach of the constriction-type Josephson junctions can be controlled\nindependently via the side gates."
    },
    {
        "anchor": "Thermotropic interface and core relaxation dynamics of liquid crystals\n  in silica glass nanochannels: A dielectric spectroscopy study: We report dielectric relaxation spectroscopy experiments on two rod-like\nliquid crystals of the cyanobiphenyl family (5CB and 6CB) confined in tubular\nnanochannels with 7 nm radius and 340 micrometer length in a monolithic,\nmesoporous silica membrane. The measurements were performed on composites for\ntwo distinct regimes of fractional filling: monolayer coverage at the pore\nwalls and complete filling of the pores. For the layer coverage a slow surface\nrelaxation dominates the dielectric properties. For the entirely filled\nchannels the dielectric spectra are governed by two thermally-activated\nrelaxation processes with considerably different relaxation rates: A slow\nrelaxation in the interface layer next to the channel walls and a fast\nrelaxation in the core region of the channel filling. The strengths and\ncharacteristic frequencies of both relaxation processes have been extracted and\nanalysed as a function of temperature. Whereas the temperature dependence of\nthe static capacitance reflects the effective (average) molecular ordering over\nthe pore volume and is well described within a Landau-de Gennes theory, the\nextracted relaxation strengths of the slow and fast relaxation processes\nprovide an access to distinct local molecular ordering mechanisms. The order\nparameter in the core region exhibits a bulk-like behaviour with a strong\nincrease in the nematic ordering just below the paranematic-to-nematic\ntransition temperature T_PN and subsequent saturation during cooling. By\ncontrast, the surface ordering evolves continuously with a kink near T_PN. A\ncomparison of the thermotropic behaviour of the monolayer with the complete\nfilling reveals that the molecular order in the core region of the pore filling\naffects the order of the peripheral molecular layers at the wall.",
        "positive": "Synthetic gauge fields and Weyl point in Time-Reversal Invariant\n  Acoustic Systems: Inspired by the discovery of quantum hall effect and topological insulator,\ntopological properties of classical waves start to draw worldwide attention.\nTopological non-trivial bands characterized by non-zero Chern numbers are\nrealized with external magnetic field induced time reversal symmetry breaking\nor dynamic modulation. Due to the absence of Faraday-like effect, the breaking\nof time reversal symmetry in an acoustic system is commonly realized with\nmoving background fluids, and hence drastically increases the engineering\ncomplexity. Here we show that we can realize effective inversion symmetry\nbreaking and effective gauge field in a reduced two-dimensional system by\nstructurally engineering interlayer couplings, achieving an acoustic analog of\nthe topological Haldane model. We then find and demonstrate unidirectional\nbackscattering immune edge states. We show that the synthetic gauge field is\nclosely related to the Weyl points in the three-dimensional band structure."
    },
    {
        "anchor": "Ultrafast stratified diffusion of water inside carbon nanotubes. Direct\n  experimental evidence with 2D (D-T2) NMR spectroscopy: Water, when confined at the nanoscale acquires extraordinary transport\nproperties. And yet there is no direct experimental evidence of these\nproperties at nanoscale resolution. Here, by using 2D NMR diffusion-relaxation\n(D-T2) and spin-lattice - spin-spin relaxation (T1-T2) spectroscopy, we\nsucceeded to resolve at the nanoscale water diffusion in single and\ndouble-walled carbon nanotubes (SWCNT/DWCNT). In SWCNTs, spectra display the\ncharacteristic shape of uniform water diffusion restricted in one dimension.\nRemarkably, in DWCNTs water is shown to split into two axial components with\nthe inner one acquiring unusual flow properties: high fragility, ultrafast\nself-diffusion coefficient, and \"rigid\" molecular environment, revealing a\nstratified cooperative motion mechanism to underlie fast diffusion in water\nsaturated CNTs.",
        "positive": "Dynamic nuclear polarization induced by hot electrons: A new method for local dynamic nuclear polarization is demonstrated in a\nGaAs/AlGaAs heterostructure at the Landau level filling factor $\\nu=3$. Using a\nnarrow channel sample, where the width varies stepwise along the electron flow,\nwe find that electron cooling (heating) causes the polarization of nuclear\nspins against (toward) the external magnetic field at liquid helium\ntemperatures. The longitudinal nuclear spin relaxation rate varies\nexponentially with inverse temperature."
    },
    {
        "anchor": "Engineered magnetization and exchange stiffness in direct-write Co-Fe\n  nanoelements: Media with engineered magnetization are essential building blocks in\nsuperconductivity, magnetism and magnon spintronics. However, the established\nthin-film and lithographic techniques insufficiently suit the realization of\nplanar components with on-demand-tailored magnetization in the lateral\ndimension. Here, we demonstrate the engineering of the magnetic properties of\nCoFe-based nanodisks fabricated by the mask-less technique of focused electron\nbeam induced deposition (FEBID). The material composition in the nanodisks is\ntuned \\emph{in-situ} via the e-beam waiting time in the FEBID process and their\npost-growth irradiation with Ga ions. The magnetization $M_s$ and exchange\nstiffness $A$ of the disks are deduced from perpendicular ferromagnetic\nresonance measurements. The achieved $M_s$ variation in the broad range from\n$720$ emu/cm$^3$ to $1430$ emu/cm$^3$ continuously bridges the gap between the\n$M_s$ values of such widely used magnonic materials as permalloy and CoFeB. The\npresented approach paves a way towards nanoscale 2D and 3D systems with\ncontrollable and space-varied magnetic properties.",
        "positive": "Interplay Between the Electric Field and the Nonlinear Interaction in\n  Ordered and Disordered Chains: A simple Kronig-Penney model is used to study the effect of nonlinear\ninteractions on the electronic properties of ordered and disordered electrified\nchains. In the case of ordered potentials, we found that the nonlinearity\nsuppresses the Wannier-Stark effect caused by the electric field. In the case\nof disordered potentials, the nonlinearity gives rise to a transition from\nsuperlocalized to weakly localized states."
    },
    {
        "anchor": "Modulation of Majorana-Induced Current Cross-Correlations by Quantum\n  Dots: We study charge transport through a topological superconductor with a pair of\nMajorana end states, coupled to leads via quantum dots with resonant levels.\nThe non-locality of the Majorana bound states opens the possibility of crossed\nAndreev reflection with nonlocal shot noise, due to the injection of an\nelectron into one end of the superconductor followed by the emission of a hole\nat the other end. In the space of energies of the two resonant quantum dot\nlevels, we find a four peaked clover-like pattern for the strength of noise due\nto crossed Andreev reflection, distinct from the single ellipsoidal peak found\nin the absence of Majorana bound states.",
        "positive": "On loss of quantum coherence in an interacting Fermi gas: We clarify the path integral calculation, recently suggested by Golubev and\nZaikin, and show, contrary to their claim, that quasiparticles become fully\ncoherent quantum particles in the $T \\to 0$ limit. The important physical point\nis the inclusion of the recoil of the quasiparticle when interacting with\nfluctuations in the rest of the Fermi gas."
    },
    {
        "anchor": "Across-Layer Sliding Ferroelectricity in Graphene-Based Heterolayers:\n  Asymmetry of Next Neighbor Interlayer Couplings: Although most two-dimensional (2D) materials are non-ferroelectric with\nhighly symmetric lattices, symmetry breaking may take place in their bilayers\nupon certain stacking order, giving rise to so-called sliding ferroelectricity\nwhere the vertical polarizations can be electrically reversed via interlayer\ntranslation. However, it is not supposed to appear in systems like graphene\nbilayer with centro-symmetry at any stacking configuration, and the origin of\nthe recently reported ferroelectricity in graphene bilayer intercalated between\nh-BN (Nature 2020, 588, 71) is still unclear. Here we propose a model of\nacross-layer sliding ferroelectricity that arises from the asymmetry of next\nneighbor interlayer couplings. The vertical polarizations in intercalated\ncentro-symmetric 2D materials like graphene bilayer can be switched via\nmultilayer sliding, and the observed ferroelectric hysteresis can be clarified.\nMoreover, such ferroelectricity can exist in a series of other heterolayers\nwith quasi-degenerate polar states, like graphene bilayer or trilayer on BN\nsubstrate, or even with a molecule layer on surface where each molecule can\nstore 1 bit data independently, resolving the bottleneck issue of sliding\nferroelectricity for high-density data storage.",
        "positive": "The Keldysh action of a multi-terminal time-dependent scatterer: We present a derivation of the Keldysh action of a general multi-channel\ntime-dependent scatterer in the context of the Landauer-B\\\"uttiker approach.\nThe action is a convenient building block in the theory of quantum transport.\nThis action is shown to take a compact form that only involves the scattering\nmatrix and reservoir Green functions. We derive two special cases of the\ngeneral result, one valid when reservoirs are characterized by well-defined\nfilling factors, the other when the scatterer connects two reservoirs. We\nillustrate its use by considering Full Counting Statistics and the Fermi Edge\nSingularity."
    },
    {
        "anchor": "Determination of the phase coherence length of PdCoO$_2$ nanostructures: The two-dimensional layered compound PdCoO$_2$ is one of the best oxide\nconductors, providing an intriguing research arena opened by the long mean free\npath and the very high mobility of ~51000 cm2/Vs. These properties turn\nPdCoO$_2$ into a candidate material for nanoscale quantum devices. By exploring\nuniversal conductance fluctuations originating at nanoscale PdCoO$_2$ Hall-bar\ndevices, we determined the phase coherence length of electron transport in\nc-axis oriented PdCoO$_2$ thin films to equal ~100 nm. The weak temperature\ndependence of the measured phase coherence length suggests that defect\nscattering at twin boundaries in the PdCoO$_2$ thin film governs phase\nbreaking. These results suggest that phase coherent devices can be achieved by\nrealizing the devices smaller than the size of twin domains, via refined\nmicrofabrication and suppression of twin boundaries.",
        "positive": "Large-signal model of the bilayer graphene field-effect transistor\n  targeting radio-frequency applications: theory versus experiment: Bilayer graphene is a promising material for radio-frequency transistors\nbecause its energy gap might result in a better current saturation than the\nmonolayer graphene. Because the great deal of interest in this technology,\nespecially for flexible radio-frequency applications, gaining control of it\nrequires the formulation of appropriate models for the drain current, charge\nand capacitance. In this work we have developed them for a dual-gated bilayer\ngraphene field-effect transistor. A drift-diffusion mechanism for the carrier\ntransport has been considered coupled with an appropriate field-effect model\ntaking into account the electronic properties of the bilayer graphene.\nExtrinsic resistances have been included considering the formation of a\nSchottky barrier at the metal-bilayer graphene interface. The proposed model\nhas been benchmarked against experimental prototype transistors, discussing the\nmain figures of merit targeting radio-frequency applications."
    },
    {
        "anchor": "On the identification of pristine and defected graphene nanoribbons by\n  phonon signatures in the electron transport characteristics: Inspired by recent experiments where electron transport was measured across\ngraphene nanoribbons (GNR) suspended between a metal surface and the tip of a\nscanning tunneling microscope [Koch \\textit{et al}., Nat. Nanotechnol. {\\bf 7},\n713 (2012)], we present detailed first-principles simulations of inelastic\nelectron tunneling spectroscopy (IETS) of long pristine and defected armchair\nand zigzag nanoribbons under a range of charge carrier conditions. For the\narmchair ribbons we find two robust IETS signals around 169 and 196 mV\ncorresponding to the D- and G-modes of Raman spectroscopy as well as additional\nfingerprints due to various types of defects in the edge passivation. For the\nzigzag ribbons we show that the spin state strongly influences the spectrum and\nthus propose IETS as an indirect proof of spin polarization.",
        "positive": "Highly tunable quadruple quantum dot in a narrow bandgap semiconductor\n  InAs nanowire: Quantum dots (QDs) made from semiconductors are among the most promising\nplatforms for the developments of quantum computing and simulation chips, and\nhave advantages over other platforms in high density integration and in\ncompatibility to the standard semiconductor chip fabrication technology.\nHowever, development of a highly tunable semiconductor multiple QD system still\nremains as a major challenge. Here, we demonstrate realization of a highly\ntunable linear quadruple QD (QQD) in a narrow bandgap semiconductor InAs\nnanowire with fine finger gate technique. The QQD is studied by electron\ntransport measurements in the linear response regime. Characteristic\ntwo-dimensional charge stability diagrams containing four groups of resonant\ncurrent lines of different slopes are found for the QQD. It is shown that these\ncurrent lines can be individually assigned as arising from resonant electron\ntransport through the energy levels of different QDs. Benefited from the\nexcellent gate tunability, we also demonstrate tuning of the QQD to regimes\nwhere the energy levels of two QDs, three QDs and all the four QDs are\nenergetically on resonance, respectively, with the fermi level of source and\ndrain contacts. A capacitance network model is developed for the linear QQD and\nthe simulated charge stability diagrams based on the model show good agreements\nwith the experiments. Our work presents a solid experimental evidence that\nnarrow bandgap semiconductor nanowires multiple QDs could be used as a\nversatile platform to achieve integrated qubits for quantum computing and to\nperform quantum simulations for complex many-body systems."
    },
    {
        "anchor": "The onset of nanoscale dissipation in superfluid He-4 at zero\n  temperature: the role of vortex shedding and cavitation: Two-dimensional flow past an infinitely long cylinder of nanoscopic radius in\nsuperfluid He-4 at zero temperature is studied by time-dependent density\nfunctional theory. The calculations reveal two distinct critical phenomena for\nthe onset of dissipation: 1) vortex-antivortex pair shedding from the periphery\nof the moving cylinder and 2) appearance of cavitation in the wake, which\npossesses similar geometry as observed experimentally for fast moving\nmicrometer-scale particles in superfluid He-4. Vortex pairs with the same\ncirculation are occasionally emitted in the form of dimers, which constitute\nthe building blocks for the Benard-von Karman vortex street structure observed\nin classical turbulent fluids and Bose-Einstein condensates. The cavitation\ninduced dissipation mechanism should be common to all superfluids that are\nself-bound and have a finite surface tension, which include the recently\ndiscovered self-bound droplets in ultracold Bose gases.",
        "positive": "Coupling of quantum-dot states via elastic-cotunneling and crossed\n  Andreev reflection in a minimal Kitaev chain: Recently, exciting progress has been made in using the superconducting\nnanowires coupled to gate-defined quantum dots (QDs) to mimic the Kiteav chain\nand realize the Majorana-bound states via a poor man's route. The essential\ningredient is to balance the interdot elastic-cotunneling (ECT) and crossed\nAndreev reflection (CAR). As theoretically proposed, this can be mediated by\nthe Andreev bound states (ABSs) formed in the superconducting nanowires.\nHowever, most of the gate-tuning asymmetric features observed in experiments\ncan not be captured using the current theoretical models. To address this\ninsufficiency, here, we consider a full model that explicitly includes all the\ndetails of both the QD states and the ABSs. Remarkable agreement is found with\nthe recent experimental observations, where our model correctly reveals the\ngate-tuning asymmetry in ECTs and by which the average QD state energy can also\nbe extracted. In contrast, CARs do not depend on the tuning of QD states.\nMoreover, armed with the tunability of ECTs and CARs with QD states, we also\npredict a controllable anisotropic superexchange interaction between electron\nspins in the two separated QDs."
    },
    {
        "anchor": "Schottky barrier lowering due to interface states in 2D heterophase\n  devices: The Schottky barrier of a metal-semiconductor junction is one of the key\nquantities affecting the charge transport in a transistor. The Schottky barrier\nheight depends on several factors, such as work function difference, local\natomic configuration in the interface, and impurity doping. We show that also\nthe presence of interface states at 2D metal-semiconductor junctions can give\nrise to a large renormalization of the effective Schottky barrier determined\nfrom the temperature dependence of the current. We investigate the charge\ntransport in n- and p-doped monolayer MoTe$_2$ 1T'-1H junctions using ab-initio\nquantum transport calculations. The Schottky barriers are extracted both from\nthe projected density of states and the transmission spectrum, and by\nsimulating the IT-characteristic and applying the thermionic emission model. We\nfind interface states originating from the metallic 1T' phase rather than the\nsemiconducting 1H phase in contrast to the phenomenon of Fermi level pinning.\nFurthermore, we find that these interface states mediate large tunneling\ncurrents which dominates the charge transport and can lower the effective\nbarrier to a value of only 55 meV.",
        "positive": "Entanglement and Disentanglement in Circuit QED Architectures: We propose a protocol for creating entanglement within a dissipative circuit\nQED network architecture that consists of two electromagnetic circuits\n(cavities) and two superconducting qubits. The system interacts with a quantum\nenvironment, giving rise to decoherence and dissipation. We discuss the\npreparation of two separate entangled cavity-qubit states via Landau-Zener\nsweeps, after which the cavities interact via a tunable \"quantum switch\" which\nis realized with an ancilla qubit. Moreover, we discuss the decay of the\nresulting entangled two-cavity state due to the influence of the environment,\nwhere we focus on the entanglement decay."
    },
    {
        "anchor": "Spin-symmetric solution of an interacting quantum dot attached to\n  superconducting leads: Andreev states and the $0-\u03c0$ transition: Behavior of Andreev gap states in a quantum dot with Coulomb repulsion\nsymmetrically attached to superconducting leads is studied via the perturbation\nexpansion in the interaction strength. We find the exact asymptotic form of the\nspin-symmetric solution for the Andreev states continuously approaching the\nFermi level. We thereby derive a critical interaction at which the Andreev\nstates at zero temperature merge at the Fermi energy, being the upper bound for\nthe $0-\\pi$ transition. We show that the spin-symmetric solution becomes\ndegenerate beyond this interaction, in the $\\pi$ phase, and the Andreev states\ndo not split unless the degeneracy is lifted. We further demonstrate that the\ndegeneracy of the spin-symmetric state extends also into the $0$ phase in which\nthe solutions with zero and non-zero frequencies of the Andreev states may\ncoexist.",
        "positive": "Negative Differential Resistance in Spin-Crossover Molecular Devices: We demonstrate, based on low-temperature scanning tunneling microscopy (STM)\nand spectroscopy, a pronounced negative differential resistance (NDR) in\nspin-crossover (SCO) molecular devices, where a Fe$^{\\text{II}}$ SCO molecule\nis deposited on surfaces. The STM measurements reveal that the NDR is robust\nwith respect to substrate materials, temperature, and the number of SCO layers.\nThis indicates that the NDR is intrinsically related to the electronic\nstructure of the SCO molecule. Experimental results are supported by density\nfunctional theory (DFT) with non-equilibrium Green's functions (NEGF)\ncalculations and a generic theoretical model. While the DFT+NEGF calculations\nreproduce NDR for a special atomically-sharp STM tip, the effect is attributed\nto the energy-dependent tip density of states rather than the molecule itself.\nWe, therefore, propose a Coulomb blockade model involving three molecular\norbitals with very different spatial localization as suggested by the molecular\nelectronic structure."
    },
    {
        "anchor": "Reading and writing charge on graphene devices: We use a combination of charge writing and scanning gate microscopy to map\nand modify the local charge neutrality point of graphene field-effect devices.\nWe give a demonstration of the technique by writing remote charge in a thin\ndielectric layer over the graphene-metal interface and detecting the resulting\nshift in local charge neutrality point. We perform electrostatic simulations to\ncharacterize the gating effect of a realistic scanning probe tip on a graphene\nbilayer and find a good agreement with the experimental results.",
        "positive": "Electron g-factor of valley states in realistic silicon quantum dots: We theoretically model the spin-orbit interaction in silicon quantum dot\ndevices, relevant for quantum computation and spintronics. Our model is based\non a modified effective mass approach with spin-valley boundary conditions,\nderived from the interface symmetry under presence of perpendicular to the\ninterface electric field. The g-factor renormalization in the two lowest valley\nstates is explained by the interface-induced spin-orbit 2D (3D) interaction,\nfavoring intervalley spin-flip tunneling over intravalley processes. We show\nthat the quantum dot level structure makes only negligible higher order effects\nto the g-factor. We calculate the g-factor as a function of the magnetic field\ndirection, which is sensitive to the interface symmetry. We identify spin-qubit\ndephasing sweet spots at certain directions of the magnetic field, where the\ng-factor renormalization is zeroed: these include perpendicular to the\ninterface magnetic field, and also in-plain directions, the latter being\ndefined by the interface-induced spin-orbit constants. The g-factor dependence\non electric field opens the possibility for fast all-electric manipulation of\nan encoded, few electron spin-qubit, without the need of a nanomagnet or a\nnuclear spin-background. Our approach of an almost fully analytic theory allows\nfor a deeper physical understanding of the importance of spin-orbit coupling to\nsilicon spin qubits."
    },
    {
        "anchor": "Spin wave modes in magnetic nanodisks under in-plane magnetic field: The size dependence of spin wave modes in a circular Permalloy (Py) nanodisk\nunder an in-plane magnetic field is systematically studied by using\nmicromagnetics simulations. We show that as the disk diameter is increased, the\nresonance frequency of the backward mode deceases while that of the uniform\nmode increases. The avoided crossing of resonance frequencies of the uniform\nmode and the backward mode appears in the plot of the size dependence of\nresonance frequencies and the backward mode turns into the so-called \"edge\nmode\" for large nanodisks.",
        "positive": "Non-linear magnetotransport in microwave-illuminated two-dimensional\n  electron systems: We study magnetoresistivity oscillations in a high-mobility two-dimensional\nelectron system subject to both microwave and dc electric fields. First, we\nobserve that the oscillation amplitude is a periodic function of the inverse\nmagnetic field and is strongly suppressed at microwave frequencies near\nhalf-integers of the cyclotron frequency. Second, we obtain a complete set of\nconditions for the differential resistivity extrema and saddle points. These\nfindings indicate the importance of scattering without microwave absorption and\na special role played by microwave-induced scattering events antiparallel to\nthe electric field."
    },
    {
        "anchor": "Phenomenology of current-skyrmion interactions in thin films with\n  perpendicular magnetic anisotropy: We study skyrmions in magnetic thin films with structural inversion asymmetry\nperpendicular to the film plane. We determine the magnetization texture of a\nsingle skyrmion and its dependence on the strength of the Dzyaloshinskii-Moriya\ninteraction relative to the magnetostatic energy. Furthermore, we construct a\nphenomenological model that describes the interaction between the motion of\nskyrmions and electric currents to lowest order in spin-orbit coupling. We\nestimate the experimental verifiable velocities for current-driven motion of\nskyrmion textures based on available results obtained from domain walls\ndynamics.",
        "positive": "Determination of $g$-factor in InAs two-dimensional electron system by\n  capacitance spectroscopy: We determine the effective $g$-factor ($|g^\\ast|$) of a two-dimensional\nelectron gas (2DEG) using a new method based on capacitance spectroscopy. The\ncapacitance-voltage profile of a 2DEG in an InAs/AlGaSb quantum well measured\nin an in-plane magnetic field shows a double-step feature that indicates the\nZeeman splitting of the subband edge. The method allows for simultaneous and\nindependent determination of $|g^\\ast|$ and effective mass $m^\\ast$. Data\nsuggest that the biaxial tensile strain in the InAs layer has considerable\nimpacts on both $m^\\ast$ and $g^\\ast$. Our method provides a means to determine\n$|g^\\ast|$ that is complementary to the commonly used coincidence technique."
    },
    {
        "anchor": "High-frequency nanotube mechanical resonators: We report on a simple method to fabricate high-frequency nanotube mechanical\nresonators reproducibly. We measure resonance frequencies as high as 4.2 GHz\nfor the fundamental eigenmode and 11 GHz for higher order eigenmodes. The\nhigh-frequency resonances are achieved using short suspended nanotubes and by\nintroducing tensile stress in the nanotube. These devices allow us to determine\nthe coefficient of the thermal expansion of an individual nanotube, which is\nnegative and is about -0.7E-5 1/K at room temperature. High-frequency\nresonators made of nanotubes hold promise for mass sensing and experiments in\nthe quantum limit.",
        "positive": "Wiggling skyrmion propagation under parametric pumping: We address the problem of how magnetic skyrmions can propagate along a guided\ndirection by parametric pumping. As evidenced by our micromagnetic simulations,\nskyrmions can hardly be driven by either a static electric field or a static\nmagnetic field alone. Although the magnetic anisotropy can be modified by an\nelectric field, parametric pumping with an oscillating electric field can only\nexcite the breathing modes. On the other hand, a static magnetic field can\nbreak rotational symmetry through the Zeeman interaction, but it cannot serve\nas an energy source for propelling a skyrmion. Here we found that the\ncombination of a perpendicularly oscillating electric field and an in-plane\nstatic magnetic field can drive a skyrmion undergoing a wiggling motion along a\nwell defined trajectory. The most efficient driving occurs when the frequency\nof the oscillating field is close to that of the breathing motion. The physics\nis revealed in a generalized Thiele equation where a net spin current excited\nby the parametric pumping can drive the skyrmion propagation through angular\nmomentum transfer. Compared with other alternative proposals, our results open\nnew possibilities for manipulating skyrmions in both metals and insulators with\nlow-power consumption. The oscillating skyrmion motion can also be a microwave\ngenerator for future spintronic applications such as an nano-tool on a diamond\nNitrogen-Vacancy center."
    },
    {
        "anchor": "Spin instabilities and quantum phase transitions in integral and\n  fractional quantum Hall states: The inter-Landau-level spin excitations of quantum Hall states at filling\nfactors nu=2 and 4/3 are investigated by exact numerical diagonalization for\nthe situation in which the cyclotron (hbar*omega_c) and Zeeman (E_Z) splittings\nare comparable. The relevant quasiparticles and their interactions are studied,\nincluding stable spin wave and skyrmion bound states. For nu=2, a spin\ninstability at a finite value of epsilon=hbar*omega_c-E_Z leads to an abrupt\nparamagnetic to ferromagnetic transition, in agreement with the mean-field\napproximation. However, for nu=4/3 a new and unexpected quantum phase\ntransition is found which involves a gradual change from paramagnetic to\nferromagnetic occupancy of the partially filled Landau level as epsilon is\ndecreased.",
        "positive": "Diagrammatic analysis of the two-state quantum Hall system with chiral\n  invariance: The quantum Hall system in the lowest Landau level with Zeeman term is\nstudied by a two-state model, which has a chiral invariance. Using a\ndiagrammatic analysis, we examine this two-state model with random impurity\nscattering, and find the exact value of the conductivity at the Zeeman energy\n$E = \\Delta$. We further study the conductivity at the another extended state\n$E = E_1$ ($ E_1 > \\Delta$). We find that the values of the conductivities at\n$E = 0$ and $E = E_1$ do not depend upon the value of the Zeeman energy\n$\\Delta$. We discuss also the case where the Zeeman energy $\\Delta$ becomes a\nrandom field."
    },
    {
        "anchor": "Negative differential resistance and effect of defects and deformations\n  in MoS2 armchair nanoribbon MOSFET: In this work we present a study on the negative differential resistance\nbehavior and the impact of various deformations {like ripples, twist, wrap} and\ndefects like vacancies and edge roughness on the electronic properties of\nshort-channel MoS2 armchair nanoribbon MOSFETs. The effect of deformation {3 to\n7 degree twist or wrap and 0.3 to 0.7 Ang rippling amplitude} and defects on a\n10 nm MoS2 ANR FET is evaluated by the density functional tight binding theory\nand the non-equilibrium Green`s function approach. We study the channel density\nof states, transmission spectra and the ID VD characteristics of such devices\nunder the varying conditions, with focus on the negative differential\nresistance behavior. Our results show significant change in the NDR peak to\nvalley ratio and the NDR window with such minor intrinsic deformations,\nespecially with the rippling.",
        "positive": "Quantum geometry induced nonlinear transport in altermagnets: Quantum geometry plays a pivotal role in the second-order response of $\\cal\nPT$-symmetric antiferromagnets. Here we study the nonlinear response of 2D\naltermagnets protected by $C_n\\cal T$ symmetry and show that their leading\nnonlinear response is third-order. Furthermore, we show that the contributions\nfrom the quantum metric and Berry curvature enter separately: the longitudinal\nresponse for all planar altermagnets \\emph{only} has a contribution from the\nquantum metric quadrupole (QMQ), while transverse responses in general have\ncontributions from both the Berry curvature quadrupole (BCQ) and QMQ. We show\nthat for the well-known example of $d$-wave altermagnets the Hall response is\ndominated by the BCQ. Both longitudinal and transverse responses are strongly\ndependent on the crystalline anisotropy. While altermagnets are strictly\ndefined in the limit of vanishing SOC, real altermagnets exhibit weak SOC,\nwhich is essential to observe this response. Specifically, SOC gaps the\nspin-group protected nodal line, generating a response peak that is sharpest\nwhen SOC is weak. Two Dirac nodes also contribute a divergence to the nonlinear\nresponse, whose scaling changes as a function of SOC. Finally, we apply our\nresults to thin films of the 3D altermagnet RuO$_2$. Our work uncovers distinct\nfeatures of altermagnets in nonlinear transport, providing experimental\nsignatures as well as a guide to disentangling the different components of\ntheir quantum geometry."
    },
    {
        "anchor": "Giant dielectric difference in chiral asymmetric bilayers: Twistronics rooted in the twist operation towards bilayer van der Waals\ncrystals is of both theoretical and technological importance. The realize of\nthe correlated electronic behaviors under this operation encourages enormous\neffort to the research on magic-angle systems which possess sensitive response\nto the external field. Here, a giant dielectric difference between 30 plus or\nminus degree twist case is observed in a typical magnetic system 2H-VSe2\nbilayer. It is shown that due to the structural inversion asymmetry in its\nmonolayer, the different stacking of the two cases corresponds to the two kind\nof valley polarized states: interlayer ferrovalley and interlayer\nantiferrovalley. Further investigations reveal that such different dielectric\nresponse between the two states stems from the different Fermi wave vectors\ncoupled to the electric field. More interestingly, we even obtain the selective\ncircularly polarized optical absorption by tuning the interlayer twist. These\nfindings open an appealing route toward functional 2D materials design for\nelectric and optical devices.",
        "positive": "Spectroscopic Visualization of a Robust Electronic Response of\n  Semiconducting Nanowires to Deposition of Superconducting Islands: Following significant progress in the visualization and characterization of\nMajorana end modes in hybrid systems of semiconducting nanowires and\nsuperconducting islands, much attention is devoted to the investigation of the\nelectronic structure at the buried interface between the semiconductor and the\nsuperconductor. The properties of that interface and the structure of the\nelectronic wavefunctions that occupy it determine the functionality and the\ntopological nature of the superconducting state induced therein. Here we study\nthis buried interface by performing spectroscopic mappings of superconducting\naluminum islands epitaxially grown in-situ on indium arsenide nanowires. We\nfind unexpected robustness of the hybrid system as the direct contact with the\naluminum islands does not lead to any change in the chemical potential of the\nnanowires, nor does it induce a significant band bending in their vicinity. We\nattribute this to the presence of surface states bound to the facets of the\nnanowire. Such surface states, that are present also in bare nanowires prior to\naluminum deposition, pin the Fermi-level thus rendering the nanowires resilient\nto surface perturbations. The aluminum islands further display Coulomb blockade\ngaps and peaks that signify the formation of a resistive tunneling barrier at\nthe InAs-Al interface. At low energies we identify a potential energy barrier\nthat further suppresses the transmittance through the interface. A\ncorresponding barrier exists in bare semiconductors between surface states and\nthe accumulation layer, induced to maintain charge neutrality. Our observations\nelucidate the delicate interplay between the resistive nature of the InAs-Al\ninterface and the ability to proximitize superconductivity and tune the\nchemical potential in semiconductor-superconductor hybrid nanowires."
    },
    {
        "anchor": "Is the regime with shot noise suppression by a factor 1/3 achievable in\n  semiconductor devices with mesoscopic dimensions?: We discuss the possibility of diffusive conduction and thus of suppression of\nshot noise by a factor 1/3 in mesoscopic semiconductor devices with\ntwo-dimensional and one-dimensional potential disorder, for which existing\nexperimental results do not provide a conclusive result. On the basis of our\nnumerical analysis, we conclude that it is quite difficult to achieve diffusive\ntransport over a reasonably wide parameter range, unless the device dimensions\nare increased up to the macroscopic scale. In addition, in the case of\none-dimensional disorder, some mechanism capable of mode-mixing has to be\npresent in order to reach or even approach the diffusive regime.",
        "positive": "The Stability and Charge Carriers in Bilayer Silicene: The structure optimization, phonon, and ab initio finite temperature\nmolecular dynamics calculations have been performed to predict that bilayer\nsilicene has stable structure with AB stacking geometry and is more favorable\nenergetically to synthesize than monolayer silicene, a two-dimensional\nhoneycomb lattice with buckled geometry. Marvellously, its electronic bands\nshow that the charge carriers behave like relativistic Dirac fermions with\nlinear energy dispersions near the K points. An insightful analysis has been\npresented to understand the low-energy electronic excitations based on\ntight-binding approximation, and we suggest that the component of sp3\nhybridization in the buckled geometry blocks the interlayer hopping, so the\nlinear dispersion can be preserved."
    },
    {
        "anchor": "Graphene spintronics: the role of ferromagnetic electrodes: We report a first principles study of spin-transport under finite bias\nthrough a graphene-ferromagnet (FM) interface, where FM=Co(111), Ni(111). The\nuse of Co and Ni electrodes achieves spin efficiencies reaching 80% and 60%,\nrespectively. This large spin filtering results from the materials specific\ninteraction between graphene and the FM which destroys the linear dispersion\nrelation of the graphene bands and leads to an opening of spin-dependent energy\ngaps of roughly 0.4-0.5 eV at the K points. The minority spin band gap resides\nhigher in energy than the majority spin band gap located near the Fermi level,\na feature that results in large minority spin dominated currents.",
        "positive": "Purifying single photon emission from giant shell CdSe/CdS quantum dots\n  at room temperature: Giant shell CdSe/CdS quantum dots are bright and flexible emitters, with\nnear-unity quantum yield and suppressed blinking, but their single photon\npurity is reduced by efficient multiexcitonic emission. We report the\nobservation, at the single dot level, of a large blueshift of the\nphotoluminescence biexciton spectrum ($24\\pm5$ nm over a sample of 32 dots) for\npure-phase wurtzite quantum dots. By spectral filtering, we demonstrate a 2.3\ntimes reduction of the biexciton quantum yield relative to the exciton\nemission, while preserving as much as 60% of the exciton single photon\nemission, thus improving the purity from $g_2(0)=0.07\\pm0.01$ to\n$g_2(0)=0.03\\pm0.01$. At larger pump fluency the spectral purification is even\nmore effective with up to a 6.6 times reduction in $g_2(0)$, which is due to\nthe suppression of higher order excitons and shell states experiencing even\nlarger blueshift. Our results indicate the potential for synthesis engineered\ngiant shell quantum dots, with further increased biexciton blueshift, for\nquantum optical applications requiring both high purity and brightness."
    },
    {
        "anchor": "Simple model for frequency response of a resonant tunneling diode caused\n  by potential change of quantum well due to electron charge: The frequency dependence of negative differential conductance (NDC) is an\nimportant property for the resonant-tunneling-diode terahertz source. Among\nseveral phenomena determining the frequency dependence, this paper shows that\nthe effect of potential change of the quantum well due to electron charge can\nbe analyzed with a simple and tractable model based on the tunneling admittance\nand capacitance. The result is identical to that of Feiginov's analysis based\non more fundamental equations, showing a one-to-one correspondence between the\nparameters of the two analyses. Similar to Feiginov's analysis, our analysis\nalso shows that NDC remains finite even at infinitely high frequency. It is\nshown in our model that this result is attributed to neglecting the tunneling\ntime at the emitter barrier. Comprehensive analysis of the frequency dependence\nof NDC will be possible by incorporating the tunneling time into the present\nmodel.",
        "positive": "Interactions and Weak Localization: Perturbation Theory and Beyond: We establish an explicit correspondence between perturbative and\nnonperturbative results in the problem of quantum decoherence in disordered\nconductors. We demonstrate that the dephasing time $\\tau_{\\phi}$ cannot be\nunambiguously extracted from a perturbative calculation. We show that the\neffect of the electron-electron interaction on the magnetoconductance is\ndescribed by the function $A_d(t)\\exp (-f_d(t))$. The dephasing time is\ndetermined by $f_d(t)$, i.e. in order to evaluate $\\tau_{\\phi}$ it is\nsufficient to perform a nonperturbative analysis with an exponential accuracy.\nThe effect of interaction on the pre-exponent $A_d(t)$ is important if one\ncalculates the interaction-dependent part of the weak localization correction\nfor strong magnetic fields. The zero temperature dephasing time drops out of\nthis correction in the first order due to the exact cancellation of the linear\nin time $T$-independent contributions from the exponent and the pre-exponent.\nNonlinear in time $T$-independent contributions do not cancel out already in\nthe first order of the perturbation theory and yield an additional contribution\nto dephasing at all temperatures including T=0."
    },
    {
        "anchor": "Theoretical study of even denominator fractions in graphene: Fermi sea\n  versus paired states of composite fermions: The physics of the state at even denominator fractional fillings of Landau\nlevels depends on the Coulomb pseudopotentials, and produces, in different GaAs\nLandau levels, a composite fermion Fermi sea, a stripe phase, or, possibly, a\npaired composite fermion state. We consider here even denominator fractions in\ngraphene, which has different pseudopotentials as well as a possible four fold\ndegeneracy of each Landau level. We test various composite fermion Fermi sea\nwave functions (fully polarized, SU(2) singlet, SU(4) singlet) as well as the\npaired composite fermion states in the n=0 and $n=1$ Landau levels and predict\nthat (i) the paired states are not favorable, (ii) CF Fermi seas occur in both\nLandau levels, and (iii) an SU(4) singlet composite fermion Fermi sea is\nstabilized in the appropriate limit. The results from detailed microscopic\ncalculations are generally consistent with the predictions of the mean field\nmodel of composite fermions.",
        "positive": "The Nanoscale Free-Electron Model: A brief review of the nanoscale free-electron model of metal nanowires is\npresented. This continuum description of metal nanostructures allows for a\nunified treatment of cohesive and conducting properties. Conductance channels\nact as delocalized chemical bonds whose breaking is responsible for jumps in\nthe conductance and force oscillations. It is argued that surface and\nquantum-size effects are the two dominant factors in the energetics of a\nnanowire, and much of the phenomenology of nanowire stability and structural\ndynamics can be understood based on the interplay of these two competing\nfactors. A linear stability analysis reveals a sequence of ``magic''\nconductance values for which the underlying nanowire geometry is exceptionally\nstable. The stable configurations include Jahn-Teller deformed wires of broken\naxial symmetry. The model naturally explains the experimentally observed shell\nand supershell structures."
    },
    {
        "anchor": "Excited-state optically detected magnetic resonance of spin defects in\n  hexagonal boron nitride: Negatively charged boron vacancy (VB-) centers in hexagonal boron nitride\n(hBN) are promising spin defects in a van der Waals crystal. Understanding the\nspin properties of the excited state (ES) is critical for realizing dynamic\nnuclear polarization. Here, we report zero-field splitting in the ES of DES =\n2160 MHz and an optically detected magnetic resonance (ODMR) contrast of 12% at\ncryogenic temperature. The ES has a g-factor similar to the ground state. The\nES photodynamics is further elucidated by measuring the level anti-crossing of\nthe VB- defects under varying external magnetic fields. In contrast to nitrogen\nvacancy (NV-) centers in diamond, the emission change caused by excited-state\nlevel anti-crossing (ESLAC) is more prominent at cryo-temperature than at room\ntemperature. Our results provide important information for utilizing the spin\ndefects of hBN in quantum technology.",
        "positive": "All-electrical control of donor-bound electron spin qubits in silicon: We propose a method to electrically control electron spins in donor-based\nqubits in silicon. By taking advantage of the hyperfine coupling difference\nbetween a single-donor and a two-donor quantum dot, spin rotation can be driven\nby inducing an electric dipole between them and applying an alternating\nelectric field generated by in-plane gates. These qubits can be coupled with\nexchange interaction controlled by top detuning gates. The qubit device can be\nfabricated deep in the silicon lattice with atomic precision by scanning\ntunneling probe technique. We have combined a large-scale full band atomistic\ntight-binding modeling approach with a time-dependent effective Hamiltonian\ndescription, providing a design with quantitative guidelines."
    },
    {
        "anchor": "Fractional Josephson Effect in Number-Conserving Systems: We study fractional Josephson effect in a particle-number conserving system\nconsisting of a quasi-one-dimensional superconductor coupled to a nanowire or\nan edge carrying $e/m$ fractional charge excitations with $m$ being an odd\ninteger. We show that, due to the topological ground-state degeneracy in the\nsystem, the periodicity of the supercurrent on magnetic flux through the\nsuperconducting loop is non-trivial which provides a possibility to detect\ntopological phases of matter by the $dc$ supercurrent measurement. Using a\nmicroscopic model for the nanowire and quasi-one-dimensional superconductor, we\nderived an effective low-energy theory for the system which takes into account\neffects of quantum phase fluctuations. We discuss the stability of the\nfractional Josephson effect with respect to the quantum phase slips in a\nmesoscopic superconducting ring with a finite charging energy.",
        "positive": "Calibrating the atomic balance by carbon nanoclusters: Carbon atoms are counted at near atomic-level precision using a scanning\ntransmission electron microscope calibrated by carbon nanocluster mass\nstandards. A linear calibration curve governs the working zone from a few\ncarbon atoms up to 34,000 atoms. This linearity enables adequate averaging of\nthe scattering cross sections, imparting the experiment with near atomic-level\nprecision despite the use of a coarse mass reference. An example of this\napproach is provided for thin layers of stacked graphene sheets. Suspended\nsheets with a thickness below 100 nm are visualized, providing quantitative\nmeasurement in a regime inaccessible to optical and scanning probe methods."
    },
    {
        "anchor": "Non-equilibrium dynamics of a system with Quantum Frustration: Using flow equations, equilibrium and non-equilibrium dynamics of a two-level\nsystem are investigated, which couples via non-commuting components to two\nindependent oscillator baths. In equilibrium the two-level energy splitting is\nprotected when the TLS is coupled symmetrically to both bath. A critical\nasymmetry angle separates the localized from the delocalized phase.\n  On the other hand, real-time decoherence of a non-equilibrium initial state\nis for a generic initial state faster for a coupling to two baths than for a\nsingle bath.",
        "positive": "Bipolar Transistor Based on Graphane: Graphane is a semiconductor with an energy gap, obtained from hydrogenation\nof the two-dimensional grapheme sheet. Together with the two-dimensional\ngeometry, unique transport features of graphene, and possibility of doping\ngraphane, p and n regions can be defined so that p-n junctions become feasible\nwith small reverse currents. Our recent analysis has shown that an ideal I-V\ncharacteristic for this type of junctions may be expected. Here, we predict the\nbehavior of bipolar juncrion transistors based on graphane. Profiles of\ncarriers and intrinsic parameters of the graphane transistor are calculated and\ndiscussed."
    },
    {
        "anchor": "Quenching of phonon-induced processes in quantum dots due to\n  electron-hole asymmetries: Differences in the confinement of electrons and holes in quantum dots are\nshown to profoundly impact the magnitude of scattering with acoustic phonons in\nmaterials where crystal deformation shifts the conduction and valence band in\nthe same direction. Using an extensive model that includes the non-Markovian\nnature of the phonon reservoir, we show how the effect may be addressed by\nphotoluminescence excitation spectroscopy of a single quantum dot. We also\ninvestigate the implications for cavity QED, i.e. a coupled quantum dot-cavity\nsystem, and demonstrate that the phonon scattering may be strongly quenched.\nThe quenching is explained by a balancing between the deformation potential\ninteraction strengths and the carrier confinement and depends on the quantum\ndot shape. Numerical examples suggest a route towards engineering the phonon\nscattering.",
        "positive": "Topologically protected wave packets and quantum rings in silicene: We study chiral wave packets moving along the zero-line of a symmetry\nbreaking potential of vertical electric field in buckled silicene using an\natomistic tight-binding approach with initial conditions set by an analytical\nsolution of the Dirac equation. We demonstrate that the wave packet moves with\na constant untrembling velocity and with a presevered shape along the zero\nline. Backscattering by the edge of the crystal is observed that appears with\nthe transition of the packet from $K$ to $K'$ valley or vice versa. We propose\na potential profile with branching of the flip line that splits the wave packet\nand produces interference of the split parts that acts as a quantum ring. The\ntransition time exhibits Aharonov-Bohm oscillations in the external magnetic\nfield that are translated to conductance oscillations when the intervalley\nscattering is present within the ring."
    },
    {
        "anchor": "Observation of acoustic Landau quantization and quantum-Hall-like edge\n  states: Many intriguing phenomena occur for electrons under strong magnetic fields.\nRecently, it was proposed that an appropriate strain texture in graphene can\ninduce a synthetic gauge field, in which the electrons behave like in a real\nmagnetic field. This opened the door to control quantum transport by mechanical\nmeans and to explore unprecedented physics in high-field regime. Such studies\nhave been achieved in molecular and photonic lattices. Here we report the first\nexperimental realization of giant uniform pseudomagnetic field in acoustics by\nintroducing a simple uniaxial deformation to acoustic graphene. Benefited from\nthe controllability of our macroscopic platform, we observe the acoustic Landau\nlevels in frequency-resolved spectroscopy and their spatial localization in\npressure-field distributions. We further visualize the quantum-Hall-like edge\nstates (connected to the zeroth Landau level), which have been elusive before\nowing to the challenge in creating large-area uniform pseudomagnetic fields.\nThese results, highly consistent with our full-wave simulations, establish a\ncomplete framework for artificial structures under constant pseudomagnetic\nfields. Our findings, conceptually novel in acoustics, may offer new\nopportunities to manipulate sound.",
        "positive": "Comparing all-optical switching in synthetic-ferrimagnetic multilayers\n  and alloys: We present an experimental and theoretical investigation of all-optical\nswitching by single femtosecond laser pulses. Our experimental results\ndemonstrate that, unlike rare earth-transition metal ferrimagnetic alloys,\nPt/Co/[Ni/Co]$_N$/Gd can be switched in the absence of a magnetization\ncompensation temperature, indicative for strikingly different switching\nconditions. In order to understand the underlying mechanism, we model the\nlaser-induced magnetization dynamics in Co/Gd bilayers and GdCo alloys on an\nequal footing, using an extension of the microscopic three-temperature model to\nmultiple magnetic sublattices and including exchange scattering. In agreement\nwith our experimental observations, the model shows that Co/Gd bilayers can be\nswitched for an arbitrary thickness of the Co layer, i.e, even far away from\ncompensating the total Co and Gd magnetic moment. We identify the switching\nmechanism in Co/Gd bilayers as a front of reversed Co magnetization that\nnucleates at the Co/Gd interface and propagates through the Co layer driven by\nexchange scattering."
    },
    {
        "anchor": "Solvable multistate model of Landau-Zener transitions in cavity QED: We consider the model of a single optical cavity mode interacting with\ntwo-level systems (spins) driven by a linearly time-dependent field. When this\nfield passes through values at which spin energy level splittings become\ncomparable to spin coupling to the optical mode, a cascade of Landau-Zener (LZ)\ntransitions leads to co-flips of spins in exchange for photons of the cavity.\nWe derive exact transition probabilities between different diabatic states\ninduced by such a sweep of the field.",
        "positive": "Spin filtering by a periodic nanospintronic devices: For a linear chain of diamond-like elements, we show that the Rashba\nspin-orbit interaction (which can be tuned by a perpendicular gate voltage) and\nthe Aharonov-Bohm flux (due to a perpendicular magnetic field) can combine to\nselect only one propagating ballistic mode, for which the electronic spins are\nfully polarized along a direction that can be tuned by the electric and\nmagnetic fields and by the electron energy. All the other modes are evanescent.\nFor a wide range of parameters, this chain can serve as a spin filter."
    },
    {
        "anchor": "Band Tuning of Phosphorene Semiconductor via Floquet Theory: Graphene and phosphorene are monolayer of graphite and phosphorous,\nrespectively. Graphene is completely relativistic (Dirac) fermionic system, but\nphosphorene is pseudorelativistic fermionic system. In phosphorene, electronic\nspectrum of phosphorene has a Dirac like (linear) band in one direction and\nSchrodinger like (parabolic) band in other direction. Conventional Rabi\noscillations are studied by using rotating wave approximation in resonance\ncase. The Floquet theory is an alternative way of study Rabi oscillations in\noff-resonance case and dominating in case of low energy physics. In this\narticle, the nonlinear optical response of graphene and phosphorene studied\nunder intense applied quantized electromagnetic field via Floquet theory. The\nBloch-Siegert shift is observed for graphene and phosphorene. A numerical model\nis applied for justifying the role of anisotropy in phosphorene. Therefore, the\nFloquet theory can be utilized to characterize the different fermionic systems.",
        "positive": "Equilibrium structures and flows of polar and nonpolar liquids and their\n  mixtures in carbon nanotubes with rectangular cross sections: Molecular dynamics (MD) simulations of equilibrium structures and flows of\npolar water, nonpolar argon and methane, and mixtures of water and methane\nconfined by single - walled carbon nanotubes (SWCNTs) with different\nrectangular cross sections have been performed. The results of these\nsimulations show that equilibrium structures and ows of all confined liquids\nsignificantly depend not only on the shape of the SWCNT's rectangular cross\nsections but also on the types of liquids inside SWCNTs."
    },
    {
        "anchor": "Resonant Enhancement of Second Harmonic Generation by Edge States in\n  Transition Metal Dichalcogenide Monolayers: We derive a low-energy theory for edge states in transition metal\ndichalcogenide monolayers for a two-band $\\bm{kp}$-Hamiltonian in case of\nuncoupled valleys. In the absence of spin-orbit interaction at the edge, these\nstates possess a linear dispersion described by a single phenomenological\nparameter characterizing the edge structure. Depending on the sign of the\nparameter, the edge state spectrum can either cross the band gap or lie outside\nof it. In the first case, the presence of edge states leads to resonant\nenhancement of the second harmonic generation at frequencies about the half of\nthe band gap, in agreement with recent experiments. The value of the\nphenomenological boundary parameter is extracted from the resonance frequency\nposition.",
        "positive": "Inversion of Zeeman splitting of exciton states in InGaAs quantum wells: Zeeman splitting of quantum-confined states of excitons in InGaAs quantum\nwells (QWs) is experimentally found to depend strongly on quantization energy.\nMoreover, it changes sign when the quantization energy increases with a\ndecrease in the QW width. In the 87-nm QW, the sign change is observed for the\nexcited quantum-confined states, which are above the ground state only by a few\nmeV. A two-step approach for the numerical solution of the two-particle\nSchroedinger equation, taking into account the Coulomb interaction and\nvalence-band coupling, is used for a theoretical justification of the observed\nphenomenon. The calculated variation of the g-factor convincingly follows the\ndependencies obtained in the experiments."
    },
    {
        "anchor": "Spin Hall effect, Hall effect and spin precession in diffusive normal\n  metals: We study transport in normal metals in an external magnetic field. This\nsystem exhibits an interplay between a transverse spin imbalance (spin Hall\neffect) caused by the spin-orbit interaction, a Hall effect via the Lorentz\nforce, and spin precession due to the Zeeman effect. Diffusion equations for\nspin and charge flow are derived. The spin and charge accumulations are\ncomputed numerically in experimentally relevant thin film geometries. The\nout-of-plane spin Hall potential is suppressed when the Larmor frequency is\nlarger than the spin-flip scattering rate. The in-plane spin Hall potential\nvanishes at zero magnetic field and attains its maximum at a finite magnetic\nfield before spin precession starts to dominate. Spin-injection via\nferromagnetic contacts creates a transverse charge Hall effect that decays in a\nfinite magnetic field due to spin precession.",
        "positive": "Phase locking of a pair of nano ferromagnetic oscillators on a\n  topological insulator: We investigate the magnetization dynamics of a pair of ferromagnetic\ninsulators (FMIs) deposited on the surface of a topological insulator (TI). Due\nto the nonlinear nature of the underlying physics and intrinsic dynamics, the\nFMIs can exhibit oscillatory behaviors even under a constant applied voltage.\nThe motion of the surface electrons of the TI, which obeys relativistic quantum\nmechanics, provides a mechanism of direct coupling between the FMIs. In\nparticular, the spin polarized current of the TI surface electrons can affect\nthe magnetization of the two FMIs, which in turn modulates the electron\ntransport, giving rise to a hybrid relativistic quantum/classical nonlinear\ndynamical system. We find robust phase and anti-phase locking between the\nmagnetization dynamics. As driving the surface electrons of a TI only requires\nextremely low power, our finding suggests that nano FMIs coupled by a spin\npolarized current on the surface of TI have the potential to serve as the\nfundamental building blocks of unconventional, low-power computing paradigms."
    },
    {
        "anchor": "{\\it Ab initio} approach to the lattice softening of an Al slab driven\n  by collective electronic excitations after ultrashort laser pulse irradiation: Recent advances in ultrashort laser pulse techniques have opened up a wide\nvariety of applications in both fundamental physics and industrial fields. In\nthis work, $ab$ $initio$ molecular dynamics simulations based on time-dependent\ndensity functional theory revealed a steady deceleration of lattice distortion\npropagation in an aluminum slab with increasing laser pulse intensity. Analysis\nof the interatomic force revealed a significant reduction in the harmonic terms\nand non-monotonic growth of anharmonicity. This behavior was characterized by\nspatially non-uniform force screening by plasmons, which is missing from\nBorn--Oppenheimer molecular dynamics, and is consistent with the current\ninterpretation of laser-induced periodic structure patterning. This work\nprovides a semi-quantitative criterion for modifying the phonon properties of\nnon-equilibrium systems.",
        "positive": "Strong Interaction between Surface Plasmons and Chiral Molecules: In plasmonic chirality, the phenomenon of circular dichroism for achiral\nnanoparitcles caused by Coulomb interaction between metal nanoparticles (NPs)\nand chiral molecules have been studied. At the same time, under the resonance\ncondition, the dye molecules and metal NPs will produce huge Rabi splitting due\nto strong coupling. If the chiral molecules are at the resonance of the\nplasmon, what will happen for the strong interaction between the plasmon and\nmolecules with chirality introduced? In this paper, we investigate a spherical\ncore-shell model and analyze its spectral phenomena under the excitation of\ncircularly polarized light (CPL). Based on Coulomb interaction between NPs and\nchiral molecules, we will show how the various factors affect the strong\ncoupling. We have obtained three mechanisms for the interaction between\nplasmons and chiral molecules: strong coupling (Rabi splitting up to 243mev),\nenhanced absorption and induced transparency. The interaction between CPL and\nchiral molecules with the opposite chirality to CPL is stronger than that of\nthe same chirality, and the line width of the two peaks is closer than that of\nthe same chirality, which shows that for the Rabi splitting with chirality,\nthere are deeper mechanisms for the interaction. This result will be helpful\nfor further research on the interaction between plasmon and molecules with\nchirality."
    },
    {
        "anchor": "Van der Waals heterostructures with spin-orbit coupling: In this article we review recent work on van der Waals (vdW) systems in which\nat least one of the components has strong spin-orbit coupling. We focus on a\nselection of vdW heterostructures to exemplify the type of interesting\nelectronic properties that can arise in these systems. We first present a\ngeneral effective model to describe the low energy electronic degrees of\nfreedom in these systems. We apply the model to study the case of (vdW) systems\nformed by a graphene sheet and a topological insulator. We discuss the\nelectronic transport properties of such systems and show how they exhibit much\nstronger spin-dependent transport effects than isolated topological insulators.\nWe then consider vdW systems in which the layer with strong spin-orbit coupling\nis a monolayer transition metal dichalcogenide (TMD) and briefly discuss\ngraphene-TMD systems. In the second part of the article we discuss the case in\nwhich the vdW system includes a superconducting layer in addition to the layer\nwith strong spin-orbit coupling. We show in detail how these systems can be\ndesigned to realize odd-frequency superconducting pair correlations. Finally,\nwe discuss twisted graphene-NbSe2 bilayer systems as an example in which the\nstrength of the proximity-induced superconducting pairing in the normal layer,\nand its Ising character, can be tuned via the relative twist angle between the\ntwo layers forming the heterostructure.",
        "positive": "Realization of an N-shaped IVC of nanoscale metallic junctions using the\n  antiferromagnetic transition: We have observed at low temperatures (<8K) hysteretic I(V) characteristics\nfor sub-mkm (~200nm) metallic break-junctions based on the heavy-fermion\ncompound UPd2Al3. Degrading the quality of the contacts by in situ increasing\nthe local residual resistivity or temperature rise reduces the hysteresis. We\ndemonstrate that those hysteretic I(V) curves can be reproduced theoretically\nby assuming the constriction to be in the thermal regime. Our calculations show\nthat such anomalous I(V) curves are due to the sharp increase of \\rho(T) of\nUPd2Al3 near the Neel temperature T_N ~ 14K. From this point of view each metal\nwith similar \\rho(T) should produce similar hysteretic I(V) curves. As example\nwe show calculations for the rare-earth manganite La{0.75}Sr{0.25}MnO3, a\nsystem with colossal magnetoresistance. In this way we demonstrate that\nnano-sized point contacts can be non-linear devices with N-shaped I(V)\ncharacteristics, i. e. with negative differential resistance, that could serve\nlike Esaki tunnel diodes or Gunn diodes as amplifiers, generators, and\nswitching units. Their characteristic response time is estimated to be less\nthan 1ns for the investigated contacts."
    },
    {
        "anchor": "Topological Semimetal Nanostructures: From Properties to Topotronics: Characterized by bulk Dirac or Weyl cones and surface Fermi-arc states,\ntopological semimetals have sparked enormous research interest in recent years.\nThe nanostructures, with large surface-to-volume ratio and easy field-effect\ngating, provide ideal platforms to detect and manipulate the topological\nquantum states. Exotic physical properties originating from these topological\nstates endow topological semimetals attractive for future topological\nelectronics (topotronics). For example, the linear energy dispersion relation\nis promising for broadband infrared photodetectors, the spin-momentum locking\nnature of topological surface states is valuable for spintronics, and the\ntopological superconductivity is highly desirable for fault-tolerant qubits.\nFor real-life applications, topological semimetals in the form of\nnanostructures are necessary in terms of convenient fabrication and\nintegration. Here, we review the recent progresses in topological semimetal\nnanostructures and start with the quantum transport properties. Then\ntopological semimetal-based electronic devices are introduced. Finally, we\ndiscuss several important aspects that should receive great effort in the\nfuture, including controllable synthesis, manipulation of quantum states,\ntopological field effect transistors, spintronic applications, and topological\nquantum computation.",
        "positive": "Barrier and finite size effects on the extension of topological\n  surface-states into magnetic insulators: The interplay between magnetic and topological order can give rise to\nphenomena such as the quantum anomalous Hall effect. The extension of\ntopological surface states into magnetic insulators (MIs) has been proposed as\nan alternative to using intrinsically magnetic topological insulators (TIs).\nHere, we theoretically study how this extension of surface states into a\nmagnetic insulator are influenced both by the interface barrier potential\nseparating a topological insulator and a magnetic insulator and by finite size\neffects in such structures. We find that the the gap in the surface states\ndepends non-monotonically on the barrier strength. A small, but finite, barrier\npotential turns out to be advantageous as it permits the surface states to\npenetrate even further into the MI. Moreover, we find that due to finite size\neffects in thin samples, increasing the spin-splitting in the MI can actually\ndecrease the gap of the surface states, in contrast to the usual expectation\nthat the gap opens as the spin-splitting increases."
    },
    {
        "anchor": "Superior dielectric breakdown strength of graphene and carbon nanotube\n  infused nano oils: Nano oils comprising Graphene nanoflakes and CNTs have been experimentally\nobserved for the first time to exhibit augmented dielectric breakdown strengths\ncompared to the base transformer oils. Variant nano oils comprising different\nGr and CNT samples suspended in two different grades of transformer oils have\nyielded consistent and high degrees of enhancement in the breakdown strength.\nThe apparent counter intuitive phenomenon of enhancing insulating caliber of\nfluids utilizing nanostructures of high electronic conductance has been shown\nto be physically consistent thorough theoretical analysis. The crux mechanism\nhas been pin pointed as efficient charge scavenging leading to hampered\nstreamer growth and development, thereby delaying probability of complete\nionization. The mathematical analysis presented provides a comprehensive\npicture of the mechanisms and physics of the electrohydrodynamics involved in\nthe phenomena of enhanced breakdown strengths. Furthermore, the analysis is\nable to physically explain the various breakdown characteristics observed as\nfunctions of system parameters, such as, nanostructure type, size distribution,\nrelative permittivity, base fluid dielectric properties, nanomaterial\nconcentration and nano oil temperature. The mathematical analyses have been\nextended to propose a physically and dimensionally consistent analytical model\nto predict the enhanced breakdown strengths of such nano oils from involved\nconstituent material properties and characteristics. The model has been\nobserved to accurately predict the augmented insulating property, thereby\nrendering it as an extremely useful tool for efficient design and prediction of\nbreakdown characteristics of nanostructure infused insulating fluids.",
        "positive": "Anisotropic AC conductivity of strained graphene: The density of states and the AC conductivity of graphene under uniform\nstrain are calculated using a new Dirac Hamiltonian that takes into account the\nmain three ingredients that change the electronic properties of strained\ngraphene: the real displacement of the Fermi energy, the reciprocal lattice\nstrain and the changes in the overlap of atomic orbitals. Our simple analytical\nexpressions of the density of states and the AC conductivity generalizes\nprevious expressions only available for uniaxial strain. The results suggest a\nway to measure the Gruneisen parameter that appears in any calculation of\nstrained graphene, as well as the emergence of a sort of Hall effect due to\nshear strain."
    },
    {
        "anchor": "Control and detection of Majorana bound states in quantum dot arrays: We study the low-energy physics of a one-dimensional array of superconducting\nquantum dots realized by proximity coupling a semiconductor nanowire to\nmultiple superconducting islands separated by narrow uncovered regions. The\neffective electrostatic potential inside the quantum dots and the uncovered\nregions can be controlled using potential gates. By performing detailed\nnumerical calculations based on effective tightbinding models, we find that\nmultiple low-energy sub-gap states consisting of partially overlapping Majorana\nbound states emerge generically in the vicinity of the uncovered regions.\nExplicit differential conductance calculations show that a robust zero-bias\nconductance peak is not inconsistent with the presence of such states localized\nthroughout the system, hence the observation of such a peak does not\ndemonstrate the realization of well-separated Majorana zero modes. However, we\nfind that creating effective potential wells in the uncovered regions traps\npairs of nearby partially overlapping Majorana bound states, which become less\nseparated and acquire a finite gap that protects the pair of Majorana zero\nmodes localized at the ends of the system. This behavior persists over a\nsignificant parameter range, suggesting that proximitized quantum dot arrays\ncould provide a platform for highly controllable Majorana devices.",
        "positive": "Non-Hermitian topological phases and exceptional lines in topolectrical\n  circuits: We propose a scheme to realize various non-Hermitian topological phases in a\ntopolectrical (TE) circuit network consisting of resistors, inductors, and\ncapacitors. These phases are characterized by topologically protected\nexceptional points and lines. The positive and negative resistive couplings Rg\nin the circuit provide loss and gain factors which break the Hermiticity of the\ncircuit Laplacian. By controlling Rg, the exceptional lines of the circuit can\nbe modulated, e.g., from open curves to closed ellipses in the Brillouin zone.\nIn practice, the topology of the exceptional lines can be detected by the\nimpedance spectra of the circuit. We also considered finite TE systems with\nopen boundary conditions, the admittance spectrum of which exhibits highly\ntunable zero-admittance states demarcated by boundary points (BPs). The phase\ndiagram of the system shows topological phases which are characterized by the\nnumber of their BPs. The transition between different phases can be controlled\nby varying the circuit parameters and tracked via impedance readout between the\nterminal nodes. Our TE model offers an accessible and tunable means of\nrealizing different topological phases in a non-Hermitian framework, and\ncharacterizing them based on their boundary point and exceptional line\nconfigurations."
    },
    {
        "anchor": "One-dimensional $2^n$-root topological insulators and superconductors: Square-root topology is a recently emerged subfield describing a class of\ninsulators and superconductors whose topological nature is only revealed upon\nsquaring their Hamiltonians, i.e., the finite energy edge states of the\nstarting square-root model inherit their topological features from the\nzero-energy edge states of a known topological insulator/superconductor present\nin the squared model. Focusing on one-dimensional models, we show how this\nconcept can be generalized to $2^n$-root topological insulators and\nsuperconductors, with $n$ any positive integer, whose rules of construction are\nsystematized here. Borrowing from graph theory, we introduce the concept of\narborescence of $2^n$-root topological insulators/superconductors which\nconnects the Hamiltonian of the starting model for any $n$, through a series of\nsquaring operations followed by constant energy shifts, to the Hamiltonian of\nthe known topological insulator/superconductor, identified as the source of its\ntopological features. Our work paves the way for an extension of $2^n$-root\ntopology to higher-dimensional systems.",
        "positive": "Orbital magnetic susceptibility of graphene and MoS2: We calculate the orbital magnetic susceptibility $\\chi_{\\mathrm{orb}}$ for an\n8-band tight-binding model of gapless and gapped graphene using Green's\nfunctions. Analogously, we study $\\chi_{\\mathrm{orb}}$ for a $\\mathrm{MoS_2}$\n12-band model. For both materials, we unravel the character of the processes\ninvolved in the magnetic response by looking at the contribution at each point\nof the Brillouin zone. By this, a clear distinction between intra- and\ninterband excitations is generally possible and we are able to predict\nqualitative features of $\\chi_{\\mathrm{orb}}$ only through the knowledge of the\nband structure. The study is complemented by comparing the magnetic response\nwith that of 2-band lattice Hamiltonians which reduce to the Dirac and\nBernevig-Hughes-Zhang (BHZ) models in the continuum limit."
    },
    {
        "anchor": "Three-dimensional Insight on the Evolution of a Supramolecular\n  Preorganization Complex to Hollow-Structure Carbon Nitride: The supramolecular preorganization approach can be applied to effectively\nfabricate various morphologies of graphitic carbon nitride(g-CN)with improved\nphotocatalytic activity, while a comprehensive understanding for the morphology\nevolution from supramolecular aggregates to g-CNs is lacking. Herein, 3D\ncharacterizations from electron tomography provide a fundamental insight on the\nevolution from rod-like melamine-cyanuric acid(MC)complex to hollow-structure\ng-CN in the thermal polycondensation process. The internal region and a group\nof surfaces of the rod-like complex initially underwent polycondensation, while\nthe other two groups of surfaces with ~100 nm thickness almost unchanged. With\nthe temperature reached to 550 degree C, the hollow-structure g-CN eventually\nformed due to most of the internal matter vanishing, and voids arose in the\npreviously unaffected surfaces(edges),resulting in a porous shell structure.\nQuantitative electron tomography indicates that the key of structure evolution\nis the differentiated condensation polymerization between edges and inner\nregion of the rod-like MC complex, which is ascribed to a higher dense of\nsurfaces and a lower dense of inner matter with loose, defective orignization.",
        "positive": "Franck-Condon blockade in suspended carbon nanotube quantum dots: Understanding the influence of vibrational motion of the atoms on electronic\ntransitions in molecules constitutes a cornerstone of quantum physics, as\nepitomized by the Franck-Condon principle of spectroscopy. Recent advances in\nbuilding molecular-electronics devices and nanoelectromechanical systems open a\nnew arena for studying the interaction between mechanical and electronic\ndegrees of freedom in transport at the single-molecule level. The tunneling of\nelectrons through molecules or suspended quantum dots has been shown to excite\nvibrational modes, or vibrons. Beyond this effect, theory predicts that strong\nelectron-vibron coupling dramatically suppresses the current flow at low\nbiases, a collective behaviour known as Franck-Condon blockade. Here we show\nmeasurements on quantum dots formed in suspended single-wall carbon nanotubes\nrevealing a remarkably large electron-vibron coupling and, due to the high\nquality and unprecedented tunability of our samples, admit a quantitative\nanalysis of vibron-mediated electronic transport in the regime of strong\nelectron-vibron coupling. This allows us to unambiguously demonstrate the\nFranck-Condon blockade in a suspended nanostructure. The large observed\nelectron-vibron coupling could ultimately be a key ingredient for the detection\nof quantized mechanical motion. It also emphasizes the unique potential for\nnanoelectromechanical device applications based on suspended graphene sheets\nand carbon nanotubes."
    },
    {
        "anchor": "Topological monopole's gauge field induced anomalous Hall effect in\n  artificial honeycomb lattice: Vortex magnetic structure in artificial honeycomb lattice provides a unique\nplatform to explore emergent properties due to the additional Berry phase\ncurvature imparted by chiral magnetization to circulating electrons via direct\ninteraction. We argue that while the perpendicularly-aligned magnetic component\nleads to the quantized flux of monopole at the center of the Berry sphere, the\nin-plane vortex circulation of magnetization gives rise to unexpected\nnon-trivial topological Berry phase due to the gauge field transformation. The\nunprecedented effect signifies the importance of vector potential in\nmultiply-connected geometrical systems. Experimental confirmations to proposed\nhypotheses are obtained from Hall resistance measurements on permalloy\nhoneycomb lattice. Investigation of the topological gauge transformation due to\nthe in-plane chirality reveals anomalous quasi-oscillatory behavior in Hall\nresistance $R_{xy}$ as function of perpendicular field. The oscillatory nature\nof $R_{xy}$ is owed to the fluctuation in equilibrium current as a function of\nFermi wave-vector $k_F$, envisaged under the proposed new formulation in this\narticle. Our synergistic approach suggests that artificially tunable\nnanostructured material provides new vista to the exploration of topological\nphenomena of strong fundamental importance.",
        "positive": "Quantum computing of molecular magnet Mn$_{12}$: Quantum computation in molecular magnets is studied by solving the\ntime-dependent Schr\\\"{o}dinger equation numerically. Following Leuenberger and\nLoss (Nature (London) 410, 789(2001)), an external oscillating magnetic field\nis applied to populate and manipulate the spin coherent states in molecular\nmagnet Mn$_{12}$. The conditions to realize parallel recording and reading data\nbases of Grover algorithsm in molecular magnets are discussed in details. It is\nfound that an accurate duration time of magnetic pulse as well as the\namplitudes are required to design the device of quantum computing."
    },
    {
        "anchor": "Co-tunneling current and shot noise in quantum dots: We derive general expressions for the current and shot noise, taking into\naccount non-Markovian memory effects. In generalization of previous approaches\nour theory is valid for arbitrary Coulomb interaction and coupling strength and\nis applicable to quantum dots and more complex systems like molecules. A\ndiagrammatic expansion up to second-order in the coupling strength, taking into\naccount co-tunneling processes, allows for a study of transport in a regime\nrelevant to many experiments. As an example, we consider a single-level quantum\ndot, focusing on the Coulomb-blockade regime. We find super-Poissonian shot\nnoise due to spin-flip co-tunneling processes at an energy scale different from\nthe one expected from first-order calculations, with a sensitive dependence on\nthe coupling strength.",
        "positive": "Universal scaling behavior of the single electron box in the strong\n  tunneling limit: We perform a numerical analysis of recently proposed scaling functions for\nthe single electron box. Specifically, we study the ``magnetic'' susceptibility\nas a function of tunneling conductance and gate charge, and the effective\ncharging energy at zero gate charge as a function of tunneling conductance in\nthe strong tunneling limit. Our Monte Carlo results confirm the accuracy of the\ntheoretical predictions."
    },
    {
        "anchor": "Magnus spin Hall and spin Nernst effects in gapped 2D Rashba systems: We study the Magnus transport in a gapped 2D electron gas with Rashba\nspin-orbit coupling using semiclassical Boltzmann transport formalism. Apart\nfrom its signature in the charge transport coefficients, the inclusion of\nMagnus velocity in the spin current operator enables us to study Magnus spin\ntransport in the system. In particular, we study the roles of mass gap and\nFermi surface topology on the behavior of Magnus Hall and Nernst conductivities\nand their spin counterparts. We find that the Magnus spin Hall conductivity\nvanishes in the limit of zero gap, unlike the universal spin Hall conductivity\n$\\sigma_s=e/(8\\pi)$. The Magnus spin currents with spin polarization\nperpendicular to the applied bias (electrical/thermal) are finite while with\npolarization along the bias vanishes. Each Magnus conductivity displays a\nplateau as Fermi energy sweeps through the gap and has peaks (whose magnitudes\ndecrease with the gap) when the Fermi energy is at the gap edges.",
        "positive": "Barrier-bound States in Flat-band Systems: As the fundamental quantum mechanical theory predicts, it is believed that\nelectronic states can be bound only to potential wells and not to potential\nbarriers in any dimension and their energies should be below the background\npotential. However, with the help of atomic lattice potentials with a flat\nelectron band in momentum space in the background, an atomically thin 1D\npotential barrier can possess barrier-centered bound states above the\nbackground potential. Here we provide a theoretical proof using Green function\npole analysis with Dyson equation that shows the existence of\nbarrier-bound-states whose energy is elevated from the flat band energy nearly\nby the barrier height. The phenomenon is believed to be independently confirmed\nin a system of Pd monolayer on a flat oxide substrate with Stoner\nferromagnetism using spin-polarized STM technique and through comparison with\nreal-space QPI simulations using realistic 2D Pd band structure."
    },
    {
        "anchor": "Theory of Microwave Parametric Down Conversion and Squeezing Using\n  Circuit QED: We study theoretically the parametric down conversion and squeezing of\nmicrowaves using cavity quantum electrodynamics of a superconducting Cooper\npair box (CPB) qubit located inside a transmission line resonator. The\nnon-linear susceptibility \\chi_2 describing three-wave mixing can be tuned by\ndc gate voltage applied to the CPB and vanishes by symmetry at the charge\ndegeneracy point. We show that the coherent coupling of different cavity modes\nthrough the qubit can generate a squeezed state. Based on parameters realized\nin recent successful circuit QED experiments, squeezing of 95% ~ 13dB below the\nvacuum noise level should be readily achievable.",
        "positive": "Cross-section geometry effects in the subband structure and spin-related\n  properties of a HgTe/CdTe nanowire: By means of a multiband effective mass Hamiltonian, a theoretical\ncharacterization of the effect of the geometrical features of the confinement\nprofile --in particular, a longitudinal groove-- on the subbands dispersion and\nspin-related properties of a rectangular HgTe/CdTe nanowire is presented.\nThrough an external electric field applied perpendicular to the wire, the\ninterplay of the induced Rashba spin splitting and these geometrical features\nis investigated. It is found that by exploiting this interplay a rich\ncomplexity of the subband structure arises, permitting the generation and\nmodulation of spin-polarized currents without magnetic fields."
    },
    {
        "anchor": "Anomalous twin boundaries in 2D materials: The high mechanical strength and excellent flexibility of 2D materials such\nas graphene are some of their most important properties [1]. Good flexibility\nis key for exploiting 2D materials in many emerging technologies, such as\nwearable electronics, bioelectronics, protective coatings and composites [1]\nand recently bending has been suggested as a route to tune electronic transport\nbehaviour [2]. For virtually all crystalline materials macroscopic deformation\nis accommodated by the movement of dislocations and through the formation of\ntwinning defects [3]; it is the geometry of the resulting microstructure that\nlargely determines the mechanical and electronic properties. Despite this, the\natomic microstructure of 2D materials after mechanical deformation has not been\nwidely investigated: only by understanding these deformed microstructures can\nthe resulting properties be accurately predicted and controlled. In this paper\nwe describe the different structural features that can form as a result of\nbending in van der Waals (vdW) crystals of 2D materials. We show that twin\nboundaries, an important class of crystal defect, are delocalised by several nm\nand not atomically sharp as has been assumed for over half a century [4]. In\naddition, we demonstrate that different classes of microstructure are present\nin the deformed material and can be predicted from just the atomic structure,\nbend angle, and flake thickness. We anticipate that this new knowledge of the\ndeformation structure for 2D materials will provide foundations for tailoring\ntransport behaviour[2], mechanical properties, liquid-phase [5,6] and\nscotch-tape exfoliation [7,8], and crystal growth.",
        "positive": "Dissipative discrete time crystals: Periodically driven quantum systems host a range of non-equilibrium phenomena\nwhich are unrealizable at equilibrium. Discrete time-translational symmetry in\na periodically driven many-body system can be spontaneously broken to form a\ndiscrete time crystal, a putative quantum phase of matter. We present the\nobservation of discrete time crystalline order in a driven system of\nparamagnetic $P$ -donor impurities in isotopically enriched $^{28}Si$ cooled\nbelow $10$ K. The observations exhibit a stable subharmonic peak at half the\ndrive frequency which remains pinned even in the presence of pulse error, a\nsignature of DTC order. We propose a theoretical model based on the\nparadigmatic central spin model which is in good agreement with experimental\nobservations, and investigate the role of dissipation in the stabilisation of\nthe DTC. Both experiment and theory indicate that the order in this system is\nprimarily a dissipative effect, and which persists in the presence of spin-spin\ninteractions. We present a theoretical phase diagram as a function of\ninteractions and dissipation for the central spin model which is consistent\nwith the experiments. This opens up questions about the interplay of coherent\ninteraction and dissipation for time-translation symmetry breaking in many-body\nFloquet systems."
    },
    {
        "anchor": "Membrane-based Optomechanical Accelerometry: Optomechanical accelerometers promise quantum-limited readout, high detection\nbandwidth, self-calibration, and radiation pressure stabilization. We present a\nsimple, scalable platform that enables these benefits with nano-$g$ sensitivity\nat acoustic frequencies, based on a pair of vertically integrated Si$_3$N$_4$\nmembranes with different stiffnesses, forming an optical cavity. As a\ndemonstration, we integrate an ultrahigh-Q ($>10^7$), millimeter-scale\nSi$_3$N$_4$ trampoline membrane above an unpatterned membrane on the same Si\nchip, forming a finesse $\\mathcal{F}\\approx2$ cavity. Using direct\nphotodetection in transmission, we resolve the relative displacement of the\nmembranes with a shot-noise-limited imprecision of 7 fm/$\\sqrt{\\text{Hz}}$,\nyielding a thermal-noise-limited acceleration sensitivity of 562\nn$g/\\sqrt{\\text{Hz}}$ over a 1 kHz bandwidth centered on the fundamental\ntrampoline resonance (40 kHz). To illustrate the advantage of radiation\npressure stabilization, we cold damp the trampoline to an effective temperature\nof 4 mK and leverage the reduced energy variance to resolve an applied\nstochastic acceleration of 50 n$g/\\sqrt{\\text{Hz}}$ in an integration time of\nminutes. In the future, we envision a small-scale array of these devices\noperating in a cryostat to search for fundamental weak forces such as dark\nmatter.",
        "positive": "Electrometry Using Coherent Exchange Oscillations in a\n  Singlet-Triplet-Qubit: Two level systems that can be reliably controlled and measured hold promise\nin both metrology and as qubits for quantum information science (QIS). When\nprepared in a superposition of two states and allowed to evolve freely, the\nstate of the system precesses with a frequency proportional to the splitting\nbetween the states. In QIS,this precession forms the basis for universal\ncontrol of the qubit,and in metrology the frequency of the precession provides\na sensitive measurement of the splitting. However, on a timescale of the\ncoherence time, $T_2$, the qubit loses its quantum information due to\ninteractions with its noisy environment, causing qubit oscillations to decay\nand setting a limit on the fidelity of quantum control and the precision of\nqubit-based measurements. Understanding how the qubit couples to its\nenvironment and the dynamics of the noise in the environment are therefore key\nto effective QIS experiments and metrology. Here we show measurements of the\nlevel splitting and dephasing due to voltage noise of a GaAs singlet-triplet\nqubit during exchange oscillations. Using free evolution and Hahn echo\nexperiments we probe the low frequency and high frequency environmental\nfluctuations, respectively. The measured fluctuations at high frequencies are\nsmall, allowing the qubit to be used as a charge sensor with a sensitivity of\n$2 \\times 10^{-8} e/\\sqrt{\\mathrm{Hz}}$, two orders of magnitude better than\nthe quantum limit for an RF single electron transistor (RF-SET). We find that\nthe dephasing is due to non-Markovian voltage fluctuations in both regimes and\nexhibits an unexpected temperature dependence. Based on these measurements we\nprovide recommendations for improving $T_2$ in future experiments, allowing for\nhigher fidelity operations and improved charge sensitivity."
    },
    {
        "anchor": "On the theory of cavities with point-like perturbations. Part I: General\n  theory: The theoretical interpretation of measurements of \"wavefunctions\" and spectra\nin electromagnetic cavities excited by antennas is considered. Assuming that\nthe characteristic wavelength of the field inside the cavity is much larger\nthan the radius of the antenna, we describe antennas as \"point-like\nperturbations\". This approach strongly simplifies the problem reducing the\nwhole information on the antenna to four effective constants. In the framework\nof this approach we overcame the divergency of series of the phenomenological\nscattering theory and justify assumptions lying at the heart of \"wavefunction\nmeasurements\". This selfconsistent approach allowed us to go beyond the\none-pole approximation, in particular, to treat the experiments with\ndegenerated states. The central idea of the approach is to introduce\n``renormalized'' Green function, which contains the information on boundary\nreflections and has no singularity inside the cavity.",
        "positive": "Contact effects in spin transport along double-helical molecules: We report on spin transport along double-helical molecular systems by\nconsidering various contact configurations and asymmetries between the two\nhelical strands in the regime of completely coherent charge transport. Our\nresults reveal that no spin polarization appears in two-terminal molecular\ndevices when coupled to one-dimensional electrodes. The same holds in the case\nof finite-width electrodes if there is a \\emph{bottleneck} of one single site\nin the system electrode--molecule--electrode. Then, additional dephasing is\nnecessary to induce spin-filtering effects. In contrast, nonzero spin\npolarization is found in molecular devices with multiple terminals or with two\nfinite-width electrodes, each of them connected to more than one site of the\nmolecule. Then, the magnitude of spin polarization can be enhanced by\nincreasing the asymmetry between the two strands. We point out that the\nspin-filtering effects could emerge in double-helical molecular devices at low\ntemperature without dephasing by a proper choice of the electrode number and\nthe connection between the molecule and the electrodes."
    },
    {
        "anchor": "A pertubative approach to the Kondo effect in magnetic atoms on\n  nonmagnetic substrates: Recent experimental advances in scanning tunneling microscopy make the\nmeasurement of the conductance spectra of isolated and magnetically coupled\natoms on nonmagnetic substrates possible. Notably these spectra are\ncharacterized by a competition between the Kondo effect and spin-flip inelastic\nelectron tunneling. In particular they include Kondo resonances and a\nlogarithmic enhancement of the conductance at voltages corresponding to\nmagnetic excitations, two features that cannot be captured by second order\nperturbation theory in the electron-spin coupling. We have now derived a third\norder analytic expression for the electron-spin self-energy, which can be\nreadily used in combination with the non-equilibrium Green's function scheme\nfor electron transport at finite bias. We demonstrate that our method is\ncapable of quantitative description the competition between Kondo resonances\nand spin-flip inelastic electron tunneling at a computational cost\nsignificantly lower than that of other approaches. The examples of Co and Fe on\nCuN are discussed in detail.",
        "positive": "Optical Hall conductivity in ordinary and graphene QHE systems: We have revealed from a numerical study that the optical Hall conductivity\n$\\sigma_{xy}(\\omega)$ has a characteristic feature even in the ac ($\\sim$ THz)\nregime in that the Hall plateaus are retained both in the ordinary\ntwo-dimensional electron gas and in graphene in the quantum Hall (QHE) regime,\nalthough the plateau height is no longer quantized in ac. In graphene\n$\\sigma_{xy}(\\omega)$ reflects the unusual Landau level structure. The effect\nremains unexpectedly robust against a significant strength of disorder, which\nwe attribute to an effect of localization. We predict the ac quantum Hall\nmeasurements are feasible through the Faraday rotation characterized by the\nfine-structure constant $\\alpha$."
    },
    {
        "anchor": "Exotic electronic states in gradient-strained untwisted graphene\n  bilayers: Many exotic electronic states were discovered in moire superlattices hosted\nin twisted homo-bilayers in the past decade, including unconventional\nsuperconductivity and correlated insulating states. However, it is technically\nchallenging to precisely and orderly stack two or more layers into certain\ntwisting angles. Here, we presented a theoretical strategy that introduces\nmoire superlattices in untwisted homo-bilayers by applying different in-plane\nstrains on the two layers of a graphene homo-bilayer, respectively. Our density\nfunctional theory calculations indicate that the graphene bilayer exhibits\nsubstantial out-of-plane corrugations that form a coloring-triangular structure\nin each moire supercell under gradient in-plane strains. Such structure leads\nto a set of kagome bands, namely one flat-band and, at least, one Dirac band,\ndeveloping along the M-K path after band-folding. For comparison, uniformly\napplied in-plane strain only yields a nearly flat band within path K-G, which\nis originated from local quantum confinement. These findings highlight the\ngradient strain as a route to feasibly fabricate exotic electronic states in\nuntwisted flexible homo-bilayers.",
        "positive": "Electronic Density of States of Atomically Resolved Single-Walled Carbon\n  Nanotubes: Van Hove Singularities and End States: The electronic density of states of atomically resolved single-walled carbon\nnanotubes have been investigated using scanning tunneling microscopy. Peaks in\nthe density of states due to the one-dimensional nanotube band structure have\nbeen characterized and compared with the results of tight-binding calculations.\nIn addition, tunneling spectroscopy measurements recorded along the axis of an\natomically-resolved nanotube exhibit new, low-energy peaks in the density of\nstates near the tube end. Calculations suggest that these features arise from\nthe specific arrangement of carbon atoms that close the nanotube end."
    },
    {
        "anchor": "Electric modulation of the Fermi arc spin transport via three-terminal\n  configuration in the topological semimetal nanowires: Spin momentum locking is a key feature of the topological surface state,\nwhich plays an important role in spintronics. The electrical detection of\ncurrent-induced spin polarization protected by the spin momentum locking in\nnon-magnetic systems provides a new platform for developing spintronics while\nprevious studies were mostly based on magnetic materials. In this study, the\nspin transport measurement of Dirac semimetal Cd3As2 was studied by the\nthree-terminal geometry, and a hysteresis loop signal with high resistance and\nlow resistance state was observed. The hysteresis was reversed by reversing the\ncurrent direction, which illustrates the spin-momentum locking feature of\nCd3As2. Furthermore, we realized the on-off states of the spin signals through\nelectric modulation of the Fermi arc via the three-terminal configuration,\nwhich enables the great potential of Cd3As2 in spin field-effect transistors.",
        "positive": "Strain-induced phase transition in CrI$_{3}$ bilayers: A monolayer of CrI$_3$ is a two-dimensional crystal that in its equilibrium\nconfiguration is a ferromagnetic semiconductor, however, two coupled layers can\nbe ferromagnetic or antiferromagnetic depending on the stacking. We study the\nmagnetic phase diagram upon the strain of the antiferromagnetically coupled\nbilayer with C2/m symmetry. We found that strain may be an efficient tool to\ntune the magnetic phase of the structure. A tensile strain stabilizes the\nantiferromagnetic phase, while a compressive strain turns the system\nferromagnetic. We understood that behavior by looking at the relative\ndisplacement between layers due to the strain. We also study the evolution of\nthe magnetic anisotropy, the magnetic exchange coupling between Cr atoms, and\nhow the Curie temperature is affected by the strain."
    },
    {
        "anchor": "Non local Andreev reflection in a carbon nanotube superconducting\n  quantum interference device: We investigate a superconducting quantum interference device (SQUID) based on\ncarbon nanotubes in a fork geometry [J.-P. Cleuziou {\\it et al.}, Nature\nNanotechnology {\\bf 1}, 53 (2006)], involving tunneling of evanescent\nquasiparticles through a superconductor over a distance comparable to the\nsuperconducting coherence length, with therefore ``non local'' processes\ngeneralizing non local Andreev reflection and elastic cotunneling. Non local\nprocesses induce a reduction of the critical current and modify the\ncurrent-phase relation. We discuss arbitrary interface transparencies. Such\ndevices in fork geometries are candidates for probing the phase coherence of\ncrossed Andreev reflection.",
        "positive": "Cavity-mediated coherent coupling between distant quantum dots: Scalable architectures for quantum information technologies require to\nselectively couple long-distance qubits while suppressing environmental noise\nand cross-talk. In semiconductor materials, the coherent coupling of a single\nspin on a quantum dot to a cavity hosting fermionic modes offers a new solution\nto this technological challenge. Here, we demonstrate coherent coupling between\ntwo spatially separated quantum dots using an electronic cavity design that\ntakes advantage of whispering-gallery modes in a two-dimensional electron gas.\nThe cavity-mediated long-distance coupling effectively minimizes undesirable\ndirect cross-talk between the dots and defines a scalable architecture for\nall-electronic semiconductor-based quantum information processing."
    },
    {
        "anchor": "Anisotropically large anomalous and topological Hall effect in a kagome\n  magnet: Recently, kagome materials have become an engrossing platform to study the\ninterplay among symmetry, magnetism, topology, and electron correlation. The\nlatest works on RMn6Sn6 (R = rare earth metal) compounds have illustrated that\nthis family could be intriguing to investigate various physical phenomena due\nto large spin-orbit coupling and strong magnetic ordering. However, combined\ntransport and spectroscopic studies in RMn6Sn6 materials are still limited.\nHere, we report magnetic, magneto-transport, and angle-resolved photoemission\nspectroscopy measurements of a kagome magnet ErMn6Sn6 that undergoes\nantiferromagnetic (TN = 345 K) to ferrimagnetic (TC = 68 K) phase transitions\nin the presence of field. We observe large anomalous and topological Hall\neffects serving as transport signatures of the nontrivial Berry curvature. The\nisothermal magnetization exhibits strong anisotropic nature and the topological\nHall effect of the compound depends on the critical field of metamagnetic\ntransition. Our spectroscopic results complemented by theoretical calculations\nshow the multi-orbital kagome fermiology. This work provides new insight into\nthe tunability and interplay of topology and magnetism in a kagome magnet.",
        "positive": "Anisotropic Fabry-P\u00e9rot resonant states confined within nano-steps\n  on the topological insulator surface: The peculiar nature of topological surface states, such as absence of\nbackscattering, weak anti-localization, and quantum anomalous Hall effect, has\nbeen demonstrated mainly in bulk and film of topological insulator (TI), using\nsurface sensitive probes and bulk transport probes. However, it is equally\nimportant and experimentally challenging to confine massless Dirac fermions\nwith nano-steps on TI surfaces. This potential structure has similar ground\nwith linearly-dispersed photons in Fabry-P\\'{e}rot resonators, while reserving\nfundamental differences from well-studied Fabry-P\\'{e}rot resonators and\nquantum corrals on noble metal surfaces. In this paper, we study the massless\nDirac fermions confined within steps along the $x$ ($\\Gamma\\mathtt{-}$K) or $y$\n($\\Gamma\\mathtt{-}$M) direction on the TI surface, and the Fabry-P\\'{e}rot-like\nresonances in the electronic local density of states (LDOS) between the steps\nare found. Due to the remarkable warping effect in the topological surface\nstates, the LDOS confined in the step-well running along $\\Gamma$-M direction\nexhibit anisotropic resonance patterns as compared to those in the step-well\nalong $\\Gamma$-K direction, which can be detected by scanning tunneling\nmicroscopy. The transmittance properties and spin orientation of Dirac fermion\nin both cases are also anisotropic in the presence of warping effect."
    },
    {
        "anchor": "New geometries for high spatial resolution hall probes: The Hall response function of symmetric and asymmetric planar Hall effect\ndevices is investigated by scanning a magnetized tip above a sensor surface\nwhile simultaneously recording the topography and the Hall voltage. Hall sensor\ngeometries are tailored using a Focused Ion Beam, in standard symmetric and new\nasymmetric geometries. With this technique we are able to reduce a single\nvoltage probe to a narrow constriction 20 times smaller than the other device\ndimensions. We show that the response function is peaked above the\nconstriction, in agreement with numerical simulations. The results suggest a\nnew way to pattern Hall sensors for enhanced spatial resolution.",
        "positive": "Weak momentum scattering and the conductivity of graphene: Electrical transport in graphene offers a fascinating parallel to spin\ntransport in semiconductors including the spin-Hall effect. In the weak\nmomentum scattering regime the steady-state density matrix contains two\ncontributions, one linear in the carrier number density $n$ and characteristic\nscattering time $\\tau$, the other independent of either. In this paper we take\nthe Liouville equation as our starting point and demonstrate that these two\ncontributions can be identified with pseudospin conservation and\nnon-conservation respectively, and are connected in a non-trivial manner by\nscattering processes. The scattering term has a distinct form, which is\npeculiar to graphene and has important consequences in transport. The\ncontribution linear in $\\tau$ is analogous to the part of the spin density\nmatrix which yields a steady state spin density, while the contribution\nindependent of $\\tau$, is analogous to the part of the spin density matrix\nwhich yields a steady state spin current. Unlike in systems with spin-orbit\ninteractions, the $n$ and $\\tau$-independent part of the conductivity is\nreinforced in the weak momentum scattering regime by scattering between the\nconserved and non-conserved pseudospin distributions."
    },
    {
        "anchor": "Elastic Strain Fields In Lateral Double Ge/Si Quantum Dots: Simulations of the elastic strain fields for double Ge/Si quantum dots\nlocated on the same wetting layer are carried out. The cluster approximation is\nused for the atomistic model based on the Keating potential. The spatial\ndistributions of the strain energy density and electron potential energy are\ncalculated using clusters containing atoms of 150 coordination spheres. It is\nshown that the used cluster boundary conditions are close to the periodic\nboundary conditions.",
        "positive": "Decoherence in qubits due to low-frequency noise: The efficiency of the future devices for quantum information processing is\nlimited mostly by the finite decoherence rates of the qubits. Recently a\nsubstantial progress was achieved in enhancing the time, which a solid-state\nqubit demonstrates a coherent dynamics. This progress is based mostly on a\nsuccessful isolation of the qubits from external decoherence sources. Under\nthese conditions the material-inherent sources of noise start to play a crucial\nrole. In most cases the noise that quantum device demonstrate has 1/f spectrum.\nThis suggests that the environment that destroys the phase coherence of the\nqubit can be thought of as a system of two-state fluctuators, which experience\nrandom hops between their states. In this short review we discuss the current\nstate of the theory of the decoherence due to the qubit interaction with the\nfluctuators. We describe the effect of such an environment on different\nprotocols of the qubit manipulations - free induction and echo signal. It turns\nout that in many important cases the noise produced by the fluctuators is\nnon-Gaussian. Consequently the results of the interaction of the qubit with the\nfluctuators are not determined by the pair correlation function only.\n  We describe the effect of the fluctuators using so-called spin-fluctuator\nmodel. Being quite realistic this model allows one to evaluate the qubit\ndynamics in the presence of one fluctuator exactly. This solution is found, and\nits features, including non-Gaussian effects are analyzed in details. We extend\nthis consideration for the systems of large number of fluctuators, which\ninteract with the qubit and lead to the 1/f noise. We discuss existing\nexperiments on the Josephson qubit manipulation and try to identify\nnon-Gaussian behavior."
    },
    {
        "anchor": "Many-body localized quantum batteries: The collective and quantum behavior of many-body systems may be harnessed to\nachieve fast charging of energy storage devices, which have been recently\ndubbed quantum batteries. In this paper, we present an extensive numerical\nanalysis of energy flow in a quantum battery described by a disordered quantum\nIsing chain Hamiltonian, whose equilibrium phase diagram presents many-body\nlocalized (MBL), Anderson localized (AL), and ergodic phases. We demonstrate\nthat i) the low amount of entanglement of the MBL phase guarantees much better\nwork extraction capabilities than the ergodic phase and ii) interactions\nsuppress temporal energy fluctuations in comparison with those of the\nnon-interacting AL phase. Finally, we show that the statistical distribution of\nvalues of the optimal charging time is a clear-cut diagnostic tool of the MBL\nphase.",
        "positive": "Effect of the long-range interaction in transport through\n  one-dimensional nanoparticle arrays: We analyze the effect of the long-range interaction on the transport\nproperties through ordered and disordered one-dimensional metallic nanoparticle\narrays. We discuss how the threshold voltage, the I-V curves and the voltage\ndrop through the array are modified as compared to the case in which\ninteractions are restricted to charges placed on the same island. We show that\nsome of these modifications are due to finite interactions between charges in\ndifferent nanoparticles while other ones are due to interactions between\ncharges in the islands and those at the electrodes, what produces a\npolarization potential drop through the array. We study the screening of the\ndisorder potential due to charges impurities trapped in the substrate and find\nthat long-range interactions introduce correlations between the disorder\npotentials of neighboring islands."
    },
    {
        "anchor": "Exciton magnetic polaron in CdTe/Cd_{1-x}Mn_{x}Te semimagnetic quantum\n  ring: Magnetically doped nanostructures can significantly enhance the interaction\nbetween the band carriers and the dopant atoms. Motivated by the demonstration\nof the enhanced sp-d exchange interaction in quantum confined structures with\nthe increased stability of the exciton magnetic polaron (EMP), we report the\nquantitative and qualitative analyses of the EMP formation in\nCdTe/Cd_{1-x}Mn_{x}Te diluted magnetic quantum ring (QR). The QR with two\ndifferent configurations: (i) the non-magnetic ring (CdTe) embedded in the\nsemimagnetic Cd_{1-x}Mn_{x}Te matrix, and (ii) magnetically non-uniform quantum\nstructures embedded with Mn2+ ions both in the ring and in the barrier regimes,\nhave been investigated for various mole fractions of the Mn dopants. The larger\npolaron binding energy (EMP) of 23meV is estimated for the 5% molar Mn contents\ncompared to the other quantum confined systems made of CdMnTe. The magnetic\nfield dependence of the MP energy and the corresponding polaron parameters like\nexchange field, localization radius of the MP, and the degree of circular\npolarization induced by the external applied magnetic field at T = 4.2K have\nbeen derived. The obtained results are in excellent agreement with the trend of\nthe significant degradation of EMP in an external magnetic field, and with the\ncontradictory tendencies of EMP for the QR with configuration (i) and (ii), as\nreported from the time-integrated measurements based on selective excitation\nfor the quantum systems made of CdMnTe and other DMS materials.",
        "positive": "Circular-Polarization-Dependent Study of Microwave-Induced Conductivity\n  Oscillations in a Two-Dimensional Electron Gas on Liquid Helium: The polarization dependence of photoconductivity response at\ncyclotron-resonance harmonics in a nondegenerate two-dimensional (2D) electron\nsystem formed on the surface of liquid helium is studied using a setup in which\na circular polarization of opposite directions can be produced. Contrary to the\nresults of similar investigations reported for semiconductor 2D electron\nsystems, for electrons on liquid helium, a strong dependence of the amplitude\nof magnetoconductivity oscillations on the direction of circular polarization\nis observed. This observation is in accordance with theoretical models based on\nphoton-assisted scattering and, therefore, it solves a critical issue in the\ndispute over the origin of microwave-induced conductivity oscillations."
    },
    {
        "anchor": "Hole spin relaxation in $p$-type (111) GaAs quantum wells: Hole spin relaxation in $p$-type (111) GaAs quantum wells is investigated in\nthe case with only the lowest hole subband, which is heavy-hole like in (111)\nGaAs/AlAs and light-hole like in (111) GaAs/InP quantum wells, being relevant.\nThe subband L\\\"{o}wdin perturbation method is applied to obtain the effective\nHamiltonian including the Dresselhaus and Rashba spin-orbit couplings. Under a\nproper gate voltage, the total in-plane effective magnetic field in (111)\nGaAs/AlAs quantum wells can be strongly suppressed in the whole momentum space,\nwhile the one in (111) GaAs/InP quantum wells can be suppressed only on a\nspecial momentum circle. The hole spin relaxation due to the D'yakonov-Perel'\nand Elliott-Yafet mechanisms is calculated by means of the fully microscopic\nkinetic spin Bloch equation approach with all the relevant scatterings\nexplicitly included. For (111) GaAs/AlAs quantum wells, extremely long\nheavy-hole spin relaxation time (upto hundreds of nanoseconds) is predicted. In\naddition, we predict a pronounced peak in the gate-voltage dependence of the\nheavy-hole spin relaxation time due to the D'yakonov-Perel' mechanism. This\npeak origins from the suppression of the unique inhomogeneous broadening in\n(111) GaAs/AlAs quantum wells. Moreover, the Elliott-Yafet mechanism influences\nthe spin relaxation only around the peak area due to the small spin mixing\nbetween the heavy and light holes in quantum wells with small well width. We\nalso show the anisotropy of the spin relaxation. In (111) GaAs/InP quantum\nwells, a mild peak, similar to the case for electrons in (111) GaAs quantum\nwells, is also predicted in the gate-voltage dependence of the light-hole spin\nrelaxation time. The contribution of the Elliott-Yafet mechanism is always\nnegligible in this case.",
        "positive": "Universal conductance fluctuations in Dirac materials in the presence of\n  long-range disorder: We study quantum transport in Dirac materials with a single fermionic Dirac\ncone (strong topological insulators and graphene in the absence of intervalley\ncoupling) in the presence of non-Gaussian long-range disorder. We show, by\ndirectly calculating numerically the conductance fluctuations, that in the\nlimit of very large system size and disorder strength, quantum transport\nbecomes universal. However, a systematic deviation away from universality is\nobtained for realistic system parameters. By comparing our results to existing\nexperimental data on 1/f noise, we suggest that many of the graphene samples\nstudied to date are in a non-universal crossover regime of conductance\nfluctuations."
    },
    {
        "anchor": "Gate-tunable Topological Valley Transport in Bilayer Graphene: Valley pseudospin, the quantum degree of freedom characterizing the\ndegenerate valleys in energy bands, is a distinct feature of two-dimensional\nDirac materials. Similar to spin, the valley pseudospin is spanned by a time\nreversal pair of states, though the two valley pseudospin states transform to\neach other under spatial inversion. The breaking of inversion symmetry induces\nvarious valley-contrasted physical properties; for instance, valley-dependent\ntopological transport is of both scientific and technological interests.\nBilayer graphene (BLG) is a unique system whose intrinsic inversion symmetry\ncan be controllably broken by a perpendicular electric field, offering a rare\npossibility for continuously tunable valley-topological transport. Here, we\nused a perpendicular gate electric field to break the inversion symmetry in\nBLG, and a giant nonlocal response was observed as a result of the topological\ntransport of the valley pseudospin. We further showed that the valley transport\nis fully tunable by external gates, and that the nonlocal signal persists up to\nroom temperature and over long distances. These observations challenge\ncontemporary understanding of topological transport in a gapped system, and the\nrobust topological transport may lead to future valleytronic applications.",
        "positive": "Dynamical projection of atoms to Feshbach molecules at strong coupling: The dynamical atom/molecule projection, recently used to probe fermion\npairing, is fast compared to collective fermion times, but slow on the Feshbach\nresonance width scale. Theory of detuning-induced dynamics of molecules coupled\nto resonantly associating atom pairs, employing a time-dependent many-body\nGreen's function approach, is presented. An exact solution is found, predicting\na 1/3 power law for molecule production efficiency at fast sweep. The results\nfor $s$- and p-wave resonances are obtained and compared. The predicted\nproduction efficiency agrees with experimental observations for both condensed\nand incoherent molecules away from saturation."
    },
    {
        "anchor": "Universal behavior of magnon-mediated spin transport in disordered\n  NM/NM/FI heterostructure: We numerically investigate the magnon-mediated spin transport and scaling\nbehaviors of a nonmagnetic metal/nonmagnetic metal/ferromagnetic insulator\n(NM/NM/FI) heterostructure in the presence of Anderson disorders. For the\ntwo-dimensional (2D) NM/NM/FI system, an enhancement of spin conductance in the\nweak disorder regime is found due to the increasing of the interfacial density\nof states (DOS) at NM/FI interface. As a result, a new scaling regime is\nuncovered in the metallic regime where the spin conductance fluctuation rms(G)\nscales linearly with the average spin conductance <G>, independent of system\nparameters such as Fermi energies and temperatures. The competition between the\ndisorder-enhanced interfacial DOS and disorder-suppressed spin transport\nresults in a non-monotonic dependence of average spin conductance on disorder\nstrength. In the localized regime, the variance of lnG for different system\nparameters follows a universal function that depends linearly on the average of\nlogarithm of spin conductance <lnG>.The distribution of lnG in the localized\nregime is non-Gaussian whose deviation from Gaussian can be characterized by\nthe third and fourth order cumulants of lnG, denoted as k3 and k4,\nrespectively. We find that k3~<-lnG>^3/2 and k4~<lnG>^2. This suggests that the\nspin conductance mediated by magnon in NM/NM/FI hybrid systems belongs to a\ndifferent universality class. For fixed <lnG>, the lnG distribution in the\nlocalized regime for different system parameters is found to collapse onto a\nsingle curve, suggesting the distribution P(lnG;<lnG>) is a universal function\nthat depends only on <lnG>. Furthermore, spin thermopower S in the presence of\ndisorder is studied and the variance of lnS is found to scale linearly with\n<lnS> for different system parameters in the localized regime. Spin conductance\nand spin thermopower for 1D NM/NM/FI are also studied.",
        "positive": "Compact localised states in magnonic Lieb lattices: Lieb lattice is one of the simplest bipartite lattices where compact\nlocalized states (CLS) are observed. This type of localisation is induced by\nthe peculiar topology of the unit cell, where the modes are localized only on\none sublattice due to the destructive interference of partial waves. The CLS\nexist in the absence of defects and are associated with the flat bands in the\ndispersion relation. The Lieb lattices were successfully implemented as optical\nlattices or photonic crystals. This work demonstrates the possibility of\nmagnonic Lieb lattice realization where the flat bands and CLS can be observed\nin the planar structure of sub-micron in-plane sizes. Using forward volume\nconfiguration, we investigated numerically (using the finite element method)\nthe Ga-dopped YIG layer with cylindrical inclusions (without Ga content)\narranged in a Lieb lattice of the period 250 nm. We tailored the structure to\nobserve, for the few lowest magnonic bands, the oscillatory and evanescent spin\nwaves in inclusions and matrix, respectively. Such a design reproduces the Lieb\nlattice of nodes (inclusions) coupled to each other by the matrix with the CLS\nin flat bands."
    },
    {
        "anchor": "Acoustomagnetoelectric effect in two-dimensional materials: Geometric\n  resonances and Weiss oscillations: We study electron transport in two-dimensional materials with parabolic and\nlinear (graphene) dispersions of the carriers in the presence of surface\nacoustic waves and an external magnetic field using semiclassical Boltzmann\nequations approach. We observe an oscillatory behavior of both the longitudinal\nand Hall electric currents as functions of the surface acoustic wave frequency\nat a fixed magnetic field and as functions of the inverse magnetic field at a\nfixed frequency of the acoustic wave. We explain the former by the phenomenon\nof geometric resonances, while we relate the latter to the Weiss-like\noscillations in the presence of the dynamic superlattice created by the\nacoustic wave. Thus we demonstrate the dual nature of the\nacoustomagnetoelectric effect in two-dimensional electron gas.",
        "positive": "Electron-phonon and electron-electron interaction effects in twisted\n  bilayer graphene: By comparing with recently available experimental data from several groups,\nwe critically discuss the manifestation of continuum many body interaction\neffects in twisted bilayer graphene (tBLG) with small twist angles and low\ncarrier densities, which arise naturally within the Dirac cone approximation\nfor the non-interacting band structure. We provide two specific examples of\nsuch continuum many body theories: one involving electron-phonon interaction\nand one involving electron-electron interaction. In both cases, the\nexperimental findings are only partially quantitatively consistent with rather\nclear-cut leading-order theoretical predictions based on well-established\ncontinuum many body theories. We provide a critical discussion, based mainly on\nthe currently available tBLG experimental data, on possible future directions\nfor understanding many body renormalization involving electron-phonon and\nelectron-electron interactions in the system. One definitive conclusion based\non the comparison between theory and experiment is that the leading order\n1-loop perturbative renormalization group theory completely fails to account\nfor the electron-electron interaction effects in the strong-coupling limit of\nflatband moir\\'e tBLG system near the magic twist angle even at low doping\nwhere the Dirac cone approximation should apply. By contrast, approximate\nnonperturbative theoretical results based on Borel-Pad\\'e resummation or $1/N$\nexpansion seems to work well compared with experiments, indicating rather small\ninteraction corrections to Fermi velocity or carrier effective mass. For\nelectron-phonon interactions, however, the leading-order continuum theory works\nwell except when van Hove singularities in the density of states come into\nplay."
    },
    {
        "anchor": "Influence of disorder and a parallel magnetic field on a Quantum Cascade\n  Laser: The luminescence spectra of a quantum cascade laser in a strong magnetic\nfield is influenced significantly by the presence of disorder (charged or\nneutral) in the system. An externally applied magnetic field parallel to the\nelectron plane causes a red shift of the luminescence peak in the absence of\nany disorder potential. Our results indicate that the disorder potential tends\nto cancel that red shift and causes a rapid decrease of the luminescence peak.\nA similar behavior was observed in a recent experiment on QCL in a parallel\nmagnetic field.",
        "positive": "Fluctuation-driven Coulomb drag in interacting quantum dot systems: Coulomb drag between nanoscale conductors is of both fundamental and\npractical interest. Here, we theoretically study drag in a double quantum-dot\n(QD) system consisting of a biased drive QD and an unbiased drag QD coupled via\na direct interdot Coulomb interaction. We demonstrate that the Coulomb drag is\ndriven by the charge fluctuations in the drive QD, and show how the properties\nof the associated quantum noise allow to distinguish it from, e.g., shot-noise\ndriven drag in circuits of weakly interacting quantum conductors. In the\nstrong-interaction regime exhibiting an orbital (\"pseudospin\") Kondo effect,\nthe drag is governed by charge fluctuations induced by pseudospin-flip\ncotunneling processes. The quenching of pseudospin-flip processes by Kondo\ncorrelations are found to suppress the drag at low bias and introduce a\nzero-bias anomaly in the second-order differential transconductance. Finally,\nwe show that the drag is maximized for values of the interdot interaction\nmatching the lead couplings. Our findings are relevant for the understanding of\ndrag in QD systems and provide experimentally testable predictions in different\ntransport regimes."
    },
    {
        "anchor": "Entanglement Distribution Statistic in Andreev Billiards: We investigate statistical aspects of the entanglement production for open\nchaotic mesoscopic billiards in contact with superconducting parts, known as\nAndreev billiards. The complete distributions of concurrence and entanglement\nof formation are obtained by using the Altland-Zirnbauer symmetry classes of\ncircular ensembles of scattering matrices, which complements previous studies\nin chaotic universal billiards belonging to other classes of random matrix\ntheory. Our results show a unique and very peculiar behavior: the realization\nof entanglement in a Andreev billiard always results in non-separable state,\nregardless of the time reversal symmetry. The analytical calculations are\nsupported by a numerical Monte Carlo simulation.",
        "positive": "Intrinsic electron spin relaxation due to the D'yakonov-Perel' mechanism\n  in monolayer MoS$_2$: Intrinsic electron spin relaxation due to the D'yakonov-Perel' mechanism is\nstudied in monolayer Molybdenum Disulphide. An intervalley in-plane spin\nrelaxation channel is revealed due to the opposite effective magnetic fields\nperpendicular to the monolayer Molybdenum Disulphide plane in the two valleys\ntogether with the intervalley electron-phonon scattering. The intervalley\nelectron-phonon scattering is always in the weak scattering limit, which leads\nto a rapid decrease of the in-plane spin relaxation time with increasing\ntemperature. A decrease of the in-plane spin relaxation time with the increase\nof the electron density is also shown."
    },
    {
        "anchor": "Topological Properties of the Chiral Magnetic Effect in Multi-Weyl\n  Semimetals: We compute the chiral magnetic effect (CME) in multi-Weyl semimetals\n(multi-WSMs) based on the chiral kinetic theory. Multi-WSMs are WSMs with\nmultiple monopole charges that have nonlinear and anisotropic dispersion\nrelations near Weyl points, and we need to extend conventional computation of\nCME in WSMs with linear dispersion relations. Topological properties of CME in\nmulti-WSMs are investigated in details for not only static magnetic fields but\nalso time-dependent (dynamic) ones. We propose an experimental setup to measure\nthe multiple monopole charge via the topological nature hidden in the dynamic\nCME.",
        "positive": "Klein tunnelling and Hartman effect in graphene junctions with proximity\n  exchange field: Tunnelling of electrons in graphene-based junctions is studied theoretically.\nGraphene is assumed to be deposited either directly on a ferromagnetic\ninsulator or on a few atomic layers of boron nitride which separate graphene\nfrom a metallic ferromagnetic substrate. Such junctions can be formed by\nappropriate external gating of the corresponding system. To describe low-energy\nelectronic states near the Dirac points, certain effective Hamiltonians\navailable in the relevant literature are used. These Hamiltonians include\nstaggered potential and exchange interaction due to ferromagnetic substrates.\nTunnelling in the systems under consideration is then spin-dependent. The main\nfocus is on Klein tunnelling and also on the group delay and the associated\nHartman effect. The impact of a gap induced in the spectrum at the Dirac points\non tunnelling is analysed in detail."
    },
    {
        "anchor": "Electric Field Switching of Magnon Spin Current in a Compensated\n  Ferrimagnet: Manipulation of directional magnon propagation, known as magnon spin current,\nis essential for developing magnonic memory and logic devices featuring\nnonvolatile functionalities and ultralow power consumption. Magnon spin current\ncan usually be modulated by magnetic field or current-induced spin torques.\nHowever, these approaches may lead to energy dissipation caused by Joule\nheating. Electric-field switching of magnon spin current without charge current\nis highly desired but very challenging to realize. By integrating magnonic and\npiezoelectric materials, we demonstrate manipulation of the magnon spin current\ngenerated by the spin Seebeck effect in the ferrimagnetic insulator Gd3Fe5O12\n(GdIG) film on a piezoelectric substrate. We observe reversible electric-field\nswitching of magnon polarization without applied charge current. Through\nstrain-mediated magnetoelectric coupling, the electric field induces the\nmagnetic compensation transition between two magnetic states of the GdIG,\nresulting in its magnetization reversal and the simultaneous switching of\nmagnon spin current. Our work establishes a prototype material platform that\npave the way for developing magnon logic devices characterized by all electric\nfield reading and writing and reveals the underlying physics principles of\ntheir functions.",
        "positive": "Filtering and imaging of frequency-degenerate spin waves using\n  nanopositioning of a single-spin sensor: Nitrogen-vacancy (NV) magnetometry is a new technique for imaging spin waves\nin magnetic materials. It detects spin waves by their microwave magnetic stray\nfields, which decay evanescently on the scale of the spin-wavelength. Here, we\nuse nanoscale control of a single-NV sensor as a wavelength filter to\ncharacterize frequency-degenerate spin waves excited by a microstrip in a\nthin-film magnetic insulator. With the NV-probe in contact with the magnet, we\nobserve an incoherent mixture of thermal and microwave-driven spin waves. By\nretracting the tip, we progressively suppress the small-wavelength modes until\na single coherent mode emerges from the mixture. In-contact scans at low drive\npower surprisingly show occupation of the entire iso-frequency contour of the\ntwo-dimensional spin-wave dispersion despite our one-dimensional microstrip\ngeometry. Our distance-tunable filter sheds light on the spin-wave band\noccupation under microwave excitation and opens opportunities for imaging\nmagnon condensates and other coherent spin-wave modes."
    },
    {
        "anchor": "Unconventional mass enhancement around the Dirac nodal loop in ZrSiS: The topological properties of fermions arise from their low-energy Dirac-like\nband dispersion and associated chiralities. Initially confined to points,\nextensions of the Dirac dispersion to lines and even loops have now been\nuncovered and semimetals hosting such features have been identified. However,\nexperimental evidence for the enhanced correlation effects predicted to occur\nin these topological semimetals has been lacking. Here, we report a quantum\noscillation study of the nodal loop semimetal ZrSiS in high magnetic fields\nthat reveals significant enhancement in the effective mass of the\nquasiparticles residing near the nodal loop. Above a threshold field, magnetic\nbreakdown occurs across gaps in the loop structure with orbits that enclose\ndifferent windings around its vertices, each winding accompanied by an\nadditional \\pi-Berry phase. The amplitudes of these breakdown orbits exhibit an\nanomalous temperature dependence. These findings demonstrate the emergence of\nnovel, correlation-driven physics in ZrSiS associated with the Dirac-like\nquasiparticles.",
        "positive": "Magnetoresistance and anomalous Hall effect in micro-ribbons of the\n  magnetic Weyl semimetal Co$_3$Sn$_2$S$_2$: Magnetic Weyl semimetals exhibit intriguing transport phenomena due to their\nnon-trivial band structure. Recent experiments in bulk crystals of the\nshandite-type Co$_3$Sn$_2$S$_2$ have shown that this material system is a\nmagnetic Weyl semimetal. To access the length scales relevant for chiral\ntransport, it is mandatory to fabricate microstructures of this fascinating\ncompound. We therefore have cut micro-ribbons (typical size\n$0.3~\\times~3~\\times~50$\\mu$m^3$) from Co$_3$Sn$_2$S$_2$ single crystals using\na focused beam of Ga$^{2+}$-ions and investigated the impact of the sample\ndimensions and possible surface doping on the magnetotransport properties. The\nlarge intrinsic anomalous Hall effect observed in the micro ribbons is\nquantitatively consistent with the one in bulk samples. Our results show that\nfocused ion beam cutting can be used for nano-patterning single crystalline\nCo$_3$Sn$_2$S$_2$, enabling future transport experiments in complex\nmicrostructures of this Weyl semimetal."
    },
    {
        "anchor": "Linear Response and the Thomas-Fermi Approximation in Undoped Graphene: We analyze the range of validity of Thomas Fermi theory for describing charge\ndensity modulations induced by external potentials in neutral graphene. We\ncompare exact results obtained from a tight-binding calculation with those of\nlinear response theory and the Thomas Fermi approximation. For experimentally\ninteresting ranges of size and density amplitudes (electron densities less than\n$\\sim 10 ^{11} cm ^{-2}$, and spatial length scales below $\\sim 20 nm$), linear\nresponse is significantly more accurate than Thomas Fermi theory.",
        "positive": "Deflection of suspended graphene by a transverse electric field: We investigate the electromechanical response of doubly clamped graphene\nnanoribbons to a transverse gate voltage. An analytical model is developed to\npredict the field-induced deformation of graphene nanoribbons as a function of\nfield intensity and graphene geometry. This model is validated thought\natomistic simulations using the combination of a constitutive charge-dipole\nmodel and a pseudo-chemical many-body potential. As a newly observed effect of\nelectric polarization, this field-induced deflection allows the graphene to\noscillate at its natural frequency, which is found to decrease dramatically\nwith increasing graphene size."
    },
    {
        "anchor": "Memristive model of hysteretic field emission from carbon nanotube\n  arrays: Some instances of electron field emitters are characterized by\nfrequency-dependent hysteresis in their current-voltage characteristics. We\nargue that such emitters can be classified as memristive systems and introduce\na general framework to describe their response. As a specific example of our\napproach, we consider field emission from a carbon nanotube array. Our\nexperimental results demonstrate a low-field hysteresis, which is likely caused\nby an electrostatic alignment of some of the nanotubes in the applied field. We\nformulate a memristive model of such phenomenon whose results are in agreement\nwith the experimental results.",
        "positive": "A parametric symmetry breaking transducer: Force detectors rely on resonators to transduce forces into a readable\nsignal. Usually these resonators operate in the linear regime and their signal\nappears amidst a competing background comprising thermal or quantum\nfluctuations as well as readout noise. Here, we demonstrate that a parametric\nsymmetry breaking transduction leads to a novel and robust nonlinear force\ndetection in the presence of noise. The force signal is encoded in the\nfrequency at which the system jumps between two phase states which are\ninherently protected against phase noise. Consequently, the transduction\neffectively decouples from readout noise channels. For a controlled\ndemonstration of the method, we experiment with a macroscopic doubly-clamped\nstring. Our method provides a promising new paradigm for high-precision force\ndetection."
    },
    {
        "anchor": "Magnetoelectric torque and edge currents caused by spin-orbit coupling: Using a tight-biding model, we elaborate that the previously discovered\nout-of-plane polarized helical edge spin current caused by Rashba spin-orbit\ncoupling can be attributed to the fact that in a strip geometry, a positive\nmomentum eigenstate does not always have the same spin polarization at the edge\nas the corresponding negative momentum eigenstate. In addition, in the presence\nof a magnetization pointing perpendicular to the edge, an edge charge current\nis produced, which can be chiral or nonchiral depending on whether the\nmagnetization lies in-plane or out-of-plane. The spin polarization near the\nedge develops a transverse component orthogonal to the magnetization, which is\nantisymmetric between the two edges and tends to cause a noncollinear magnetic\norder between the two edges. If the magnetization only occupies a region near\none edge, or in an irregular shaped quantum dot, this transverse component has\na nonzero average, rendering a gate voltage-induced magnetoelectric torque\nwithout the need of a bias voltage. We also argue that other types of\nspin-orbit coupling that can be obtained from the Rashba type through a unitary\ntransformation, such as the Dresselhaus spin-orbit coupling, will have similar\neffects too.",
        "positive": "Optical Phase Measurement Using a Deterministic Source of Entangled\n  Multi-photon States: Precision measurements of optical phases have many applications in science\nand technology. Entangled multi-photon states have been suggested for\nperforming such measurements with precision that significantly surpasses the\nshot-noise limit. Until recently, such states have been generated mainly using\nspontaneous parametric down-conversion -- a process which is intrinsically\nprobabilistic, counteracting the advantages that the entangled photon states\nmight have. Here, we use a semiconductor quantum dot to generate entangled\nmulti-photon states in a deterministic manner, using periodic timed excitation\nof a confined spin. This way we entangle photons one-by-one at a rate which\nexceeds 300 MHz. We use the resulting multi-photon state to demonstrate\nsuper-resolved optical phase measurement. Our results open up a scalable way\nfor realizing genuine quantum enhanced super-sensitive measurements in the near\nfuture."
    },
    {
        "anchor": "Dynamics of spin-2 Bose condensate driven by external magnetic fields: Dynamic response of the F=2 spinor Bose-Einstein condensate (BEC) under the\ninfluence of external magnetic fields is studied. A general formula is given\nfor the oscillation period to describe population transfer from the initial\npolar state to other spin states. We show that when the frequency and the\nreduced amplitude of the longitudinal magnetic field are related in a specific\nmanner, the population of the initial spin-0 state will be dynamically\nlocalized during time evolution. The effects of external noise and nonlinear\nspin exchange interaction on the dynamics of the spinor BEC are studied. We\nshow that while the external noise may eventually destroy the Rabi oscillations\nand dynamic spin localization, these coherent phenomena are robust against the\nnonlinear atomic interaction.",
        "positive": "Allotropic Ga$_2$Se$_3$/GaSe nanostructures grown by van der Waals\n  epitaxy: Narrow exciton lines and single-photon emission: The ability to emit narrow exciton lines, preferably with a clearly defined\npolarization, is one of the key conditions for the use of nanostructures based\non III-VI monochalcogenides and other layered crystals in quantum technology to\ncreate non-classical light. Currently, the main method of their formation is\nexfoliation followed by strain and defect engineering. A factor limiting the\nuse of epitaxy is the presence of different phases in the grown films. In this\nwork, we show that control over their formation makes it possible to create\nstructures with the desired properties. We propose Ga$_2$Se$_3$/GaSe\nnanostructures by van der Waals epitaxy with a high VI/III flux ratio as a\nsource of narrow exciton lines. Actually, these nanostructures are a\ncombination of allotropes: GaSe and Ga$_2$Se$_3$, consisting of the same atoms\nin different arrangements. The energy position of the narrow lines is\ndetermined by the quantum confinement in Ga$_2$Se$_3$ inclusions of different\nsizes in the GaSe matrix, similar to quantum dots, and their linear\npolarization is due to the ordering of Ga vacancies in a certain crystalline\ndirection in Ga$_2$Se$_3$. Such nanostructures exhibit single-photon emission\nwith second-order correlation function $g^{(2)}(0)\\sim$0.1 at 10 K that makes\nthem promising for quantum technologies."
    },
    {
        "anchor": "Quantum conductance of graphene nanoribbons with edge defects: The conductance of metallic graphene nanoribbons (GNRs) with single defects\nand weak disorder at their edges is investigated in a tight-binding model. We\nfind that a single edge defect will induce quasi-localized states and\nconsequently cause zero-conductance dips. The center energies and breadths of\nsuch dips are strongly dependent on the geometry of GNRs. Armchair GNRs are\nmuch more sensitive to a vacancy than zigzag GNRs, but are less sensitive to a\nweak scatter. More importantly, we find that with a weak disorder, zigzag GNRs\nwill change from metallic to semiconducting due to Anderson localization. But a\nweak disorder only slightly affects the conductance of armchair GNRs. The\ninfluence of edge defects on the conductance will decrease when the widths of\nGNRs increase.",
        "positive": "Optimizing magneto-dipolar interactions for synchronizing vortex based\n  spin-torque nano-oscillators: We report on a theoretical study about the magneto-dipolar coupling and\nsynchronization between two vortex-based spin-torque nano-oscillators. In this\nwork we study the dependence of the coupling efficiency on the relative\nmagnetization parameters of the vortices in the system. For that purpose, we\ncombine micromagnetic simulations, Thiele equation approach, and analytical\nmacro-dipole approximation model to identify the optimized configuration for\nachieving phase-locking between neighboring oscillators. Notably, we compare\nvortices configurations with parallel (P) polarities and with opposite (AP)\npolarities. We demonstrate that the AP core configuration exhibits a coupling\nstrength about three times larger than in the P core configuration."
    },
    {
        "anchor": "Holonomic implementation of CNOT gate on topological Majorana qubits: The CNOT gate is a two-qubit gate which is essential for universal quantum\ncomputation. A well-established approach to implement it within Majorana-based\nqubits relies on subsequent measurement of (joint) Majorana parities. We\npropose an alternative scheme which operates a protected CNOT gate via the\nholonomic control of a handful of system parameters, without requiring any\nmeasurement. We show how the adiabatic tuning of pair-wise couplings between\nMajoranas can robustly lead to the full entanglement of two qubits, insensitive\nwith respect to small variations in the control of the parameters.",
        "positive": "Robust Topological Bound States in the Continuum in a Quantum Hall Bar\n  with an Anti-dot: Bound states in the continuum (BICs) are quantum states with normalizable\nwave functions and energies that lie within the continuous spectrum for which\nextended or dispersive states are also available. These special states, which\nhave shown great applicability in photonic systems for devices such as lasers\nand sensors, are also predicted to exist in electronic low-dimensional\nsolid-state systems. The non-trivial topology of materials is within the known\nmechanisms that prevent the bound states to couple with the extended states. In\nthis work we search for topologically protected BICs in a quantum Hall bar with\nan anti-dot formed by a pore far from the borders of the bar. The bound state\nenergies and wavefunctions are calculated by means of the Recursive S-Matrix\nmethod. The resulting bound state energies coexist with extended states and\nexhibit a pattern complimentary to the Hofstadter butterfly. A\nsymmetry-breaking diagonal disorder was introduced, showing that the BICs with\nenergies far from the Landau levels remain robust. Moreover, the energy\ndifference between consecutive BICs multiplied by the anti-dot perimeter\nfollows the same curve despite disorder. Finally, a BIC-mediated current\nswitching effect was found in a multi-terminal setup, which might permit their\nexperimental detection."
    },
    {
        "anchor": "Elementary excitations of trapped Bose gas in the large-gas-parameter\n  regime: We study the effect of going beyond the Gross-Pitaevskii theory on the\nfrequencies of collective oscillations of a trapped Bose gas in the large gas\nparameter regime. We go beyond the Gross-Pitaevskii regime by including a\nhigher-order term in the interatomic correlation energy. To calculate the\nfrequencies we employ the sum-rule approach of many-body response theory\ncoupled with a variational method for the determination of ground-state\nproperties. We show that going beyond the Gross-Pitaevskii approximation\nintroduces significant corrections to the collective frequencies of the\ncompressional mode.",
        "positive": "Microwave spectroscopy of interacting Andreev spins: Andreev bound states are fermionic states localized in weak links between\nsuperconductors which can be occupied with spinful quasiparticles. Microwave\nexperiments using superconducting circuits with InAs/Al nanowire Josephson\njunctions have recently enabled probing and coherent manipulation of Andreev\nstates but have remained limited to zero or small fields. Here we use a\nflux-tunable superconducting circuit in external magnetic fields up to 1T to\nperform spectroscopy of spin-polarized Andreev states up to ~250 mT, beyond\nwhich the spectrum becomes gapless. We identify singlet and triplet states of\ntwo quasiparticles occupying different Andreev states through their dispersion\nin magnetic field. These states are split by exchange interaction and couple\nvia spin-orbit coupling, analogously to two-electron states in quantum dots. We\nalso show that the magnetic field allows to drive a direct spin-flip transition\nof a single quasiparticle trapped in the junction. Finally, we measure a gate-\nand field-dependent anomalous phase shift of the Andreev spectrum, of magnitude\nup to approximately $0.7\\pi$. Our observations demonstrate new ways to\nmanipulate Andreev states in a magnetic field and reveal spin-polarized triplet\nstates that carry supercurrent."
    },
    {
        "anchor": "Chemical-potential flow equations for graphene with Coulomb interactions: We calculate the chemical potential dependence of the renormalized Fermi\nvelocity and static dielectric function for Dirac quasiparticles in graphene\nnonperturbatively at finite temperature. By reinterpreting the chemical\npotential as a flow parameter in the spirit of the functional renormalization\ngroup (fRG) we obtain a set of flow equations, which describe the change of\nthese functions upon varying the chemical potential. In contrast to the fRG the\ninitial condition of the flow is nontrivial and has to be calculated\nseparately. Our results confirm that the charge carrier density dependence of\nthe Fermi velocity is negligible, validating the comparison of the fRG\ncalculation at zero density of Bauer et al., Phys. Rev. B 92, 121409 (2015)\nwith the experiment of Elias et al., Nat. Phys. 7, 701 (2011).",
        "positive": "Chiral Quasiparticle Tunneling Between Quantum Hall Edges in Proximity\n  with a Superconductor: We study a two-terminal graphene Josephson junction with contacts shaped to\nform a narrow constriction, less than 100nm in length. The contacts are made\nfrom type II superconducting contacts and able to withstand magnetic fields\nhigh enough to reach the quantum Hall (QH) regime in graphene. In this regime,\nthe device conductance is determined by edge states, plus the contribution from\nthe constricted region. In particular, the constriction area can support\nsupercurrents up to fields of ~2.5T. Moreover, enhanced conductance is observed\nthrough a wide range of magnetic fields and gate voltages. This additional\nconductance and the appearance of supercurrent is attributed to the tunneling\nbetween counter-propagating quantum Hall edge states along opposite\nsuperconducting contacts."
    },
    {
        "anchor": "Dynamics of a one-dimensional spinor Bose liquid: a phenomenological\n  approach: The ground state of a spinor Bose liquid is ferromagnetic, while the softest\nexcitation above the ground state is the magnon mode. The dispersion relation\nof the magnon in a one-dimensional liquid is periodic in the wavenumber q with\nthe period 2\\pi n, determined by the density n of the liquid. Dynamic\ncorrelation functions, such as e.g. spin-spin correlation function, exhibit\npower-law singularities at the magnon spectrum, $\\omega\\to\\omega_m(q,n)$.\nWithout using any specific model of the inter-particle interactions, we relate\nthe corresponding exponents to independently measurable quantities\n$\\partial\\omega_m/\\partial q$ and $\\partial\\omega_m/\\partial n$.",
        "positive": "Single-junction quantum-circuit refrigerator: We propose a quantum-circuit refrigerator (QCR) based on photon-assisted\nquasiparticle tunneling through a single\nnormal-metal--insulator--superconductor (NIS) junction. In contrast to previous\nworks with multiple junctions and an additional charge island for the QCR, we\ngalvanically connect the NIS junction to an inductively shunted electrode of a\nsuperconducting microwave resonator making the device immune to low-frequency\ncharge noise. At low characteristic impedance of the resonator and parameters\nrelevant to a recent experiment, we observe that a semiclassical impedance\nmodel of the NIS junction reproduces the bias voltage dependence of the\nQCR-induced damping rate and frequency shift. For high characteristic\nimpedances, we derive a Born--Markov master equation and use it to observe\nsignificant non-linearities in the QCR-induced dissipation and frequency shift.\nWe further demonstrate that in this regime, the QCR can be used to initialize\nthe linear resonator into a non-thermal state even in the absence of any\nmicrowave drive."
    },
    {
        "anchor": "Superballistic electron flow through a point contact in a Ga[Al]As\n  heterostructure: We measure electronic transport through point contacts in the high-mobility\nelectron gas in a Ga[Al]As heterostructure at different temperatures and bulk\nelectron densities. The conductance through all point contacts increases with\nincreasing temperature in a temperature window around $T \\sim 10 K$ for all\ninvestigated electron densities and point contact widths. For high electron\ndensities this conductance exceeds the fundamental ballistic limit (Sharvin\nlimit). These observations are in agreement with a viscous electron transport\nmodel and previous experiments in graphene.",
        "positive": "Collective motions of a quantum gas confined in a harmonic trap: Single-component quantum gas confined in a harmonic potential, but otherwise\nisolated, is considered. From the invariance of the system of the gas under a\ndisplacement-type transformation, it is shown that the center of mass\noscillates along a classical trajectory of a harmonic oscillator. It is also\nshown that this harmonic motion of the center has, in fact, been implied by\nKohn's theorem. If there is no interaction between the atoms of the gas, the\nsystem in a time-independent isotropic potential of frequency $\\nu_c$ is\ninvariant under a squeeze-type unitary transformation, which gives collective\n{\\it radial} breathing motion of frequency $2\\nu_c$ to the gas. The amplitudes\nof the oscillating and breathing motions from the {\\it exact} invariances could\nbe arbitrarily large. For a Fermi system, appearance of $2\\nu_c$ mode of the\nlarge breathing motion indicates that there is no interaction between the\natoms, except for a possible long-range interaction through the\ninverse-square-type potential."
    },
    {
        "anchor": "Narrowband nanomechanical mass measurement using nonlinear response of a\n  graphene membrane: We propose a scheme to measure the mass of a single particle using the\nnonlinear response of a 2D nanoresonator with degenerate eigenmodes. Using\nnumerical and analytical calculations, we show that by driving a square\ngraphene nanoresonator into the nonlinear regime, simultaneous determination of\nthe mass and position of an added particle is possible. Moreover, this scheme\nonly requires measurements in a narrow frequency band near the fundamental\nresonance.",
        "positive": "Electron tunneling spectroscopy of a quantum antidot in the quantum Hall\n  regime: Quantum antidot, a small potential hill introduced into a two-dimensional\nelectron system, presents an attractive tool to study quantum mechanics of\ninteracting electrons.Here, we report experiments on electron resonant\ntunneling via a quantum antidot on the integer i = 1, 2, 3, 4, 5, and 6 quantum\nHall plateaus. Several new features are reported. First, as a function of\nmagnetic field, we observe up to six quasiperiodic resonant tunneling peaks\nwithin the fundamental flux period: when flux h/e is added to the area of the\nantidot there are i peaks on the i-th integer plateau, when i spin-polarized\nLandau levels are occupied. Corresponding back gate voltage data show one peak\nper added charge e on all integer plateaus. Second, we observe tunneling dips\nin four-terminal resistance (\"forward scattering\") on the even i = 2, 4, and 6\nplateaus, when population of both spins is nearly equal. Also, for the first\ntime, we report an internal structure within the h/e period: on the i = 3\nspin-split plateau, two of the three resonant tunneling peaks are higher and/or\ncloser than the third. Puzzlingly, in this regime, when back gate voltage is\nswept, the tunneling peaks are grouped in pairs. These results are attributed\nto the dominance of the electron-electron Coulomb interaction, effectively\nmixing Landau level occupation, and to the self-consistent electrostatics of\nthe antidot."
    },
    {
        "anchor": "Quantum Interference Transport in two-dimensional Semi-Dirac Semimetals: Semi-Dirac semimetals have received enthusiastic research both theoretically\nand experimentally in the recent years. Due to the anisotropic dispersion, its\nphysical properties are highly direction-dependent. In this work we employ the\nFeynman diagrammatic perturbation theory to study the transport properties in\nquantum diffusive regime. The magneto-conductivity with quantum interference\ncorrections is derived, which demonstrate the weak localization effect in the\nsemi-Dirac semimetal. Furthermore, the origin of anomalous Hall conductivity is\nalso clarified, where both the intrinsic and side-jump contributions vanish and\nonly the skew-scattering gives rise to non-zero transverse conductivity. The\nconductance fluctuations in both mesoscopic and quantum diffusive regimes are\ninvestigated in detail. Our work provides theoretical predictions for transport\nexperiments, which can be examined by conductivity measurements at sufficiently\nlow temperature.",
        "positive": "Differentiating Majorana from Andreev Bound States in a Superconducting\n  Circuit: We investigate the low-energy theory of a one-dimensional finite capacitance\ntopological Josephson junction. Charge fluctuations across the junction couple\nto resonant microwave fields and can be used to probe microscopic excitations\nsuch as Majorana and Andreev bound states. This marriage between localized\nmicroscopic degrees of freedom and macroscopic dynamics of the superconducting\nphase, leads to unique spectroscopic patterns which allow us to reveal the\npresence of Majorana fermions among the low-lying excitations."
    },
    {
        "anchor": "Resonant enhancement of the near-field radiative heat transfer in\n  nanoparticles: We numerically study the tuning of the radiative heat transfer between a\nspherical InSb nanoparticle in the vicinity of a flat SiC surface assisted by a\nstatic magnetic field. By changing the value of the applied magnetic field, the\ndielectric function of the nanosphere becomes anisotropic due to the excitation\nof magneto-plasmons. In the dipolar approximation, the plasmon resonance of the\nparticle splits into two additional satellite resonances that shift to higher\nand lower frequencies as the field increases. When one of the particle\nresonances overlaps with the phonon-polariton frequency of the SiC surface, an\nenhancement of the heat transfer of two orders of magnitude is obtained. To\nunderstand the tuning of the radiative heat transfer, we present a detailed\nanalysis of the nature of the modes that can be excited (surface, bulk, and\nhyperbolic).",
        "positive": "Quantum dot coupled to topological insulators: The role of edge states: We investigate a system consisting of one or two topological-insulator leads\nwhich are tunnel coupled to a single dot level. The leads are described by the\none-dimensional Su-Schrieffer-Heeger model. We show that (topological) edge\nstates cause characteristic features in the dot spectral function, the dot\noccupation, and the finite-bias current across the dot. As the kinetic energy\nis quenched in the dot region, local two-particle interactions are of\nparticular relevance there. This motivates us to test whether the\naforementioned edge-state features are robust against such interactions; we\nreport here that they are either robust or even enhanced. We conclude that the\ncharacteristic features can be used to determine if the leads are in their\ntopologically non-trivial or trivial phase."
    },
    {
        "anchor": "From chaos to disorder: Statistics of the eigenfunctions of microwave\n  cavities: We study the statistics of the experimental eigenfunctions of chaotic and\ndisordered microwave billiards in terms of the moments of their spatial\ndistributions, such as the Inverse Participation Ratio (IPR) and\ndensity-density auto-correlation. A path from chaos to disorder is described in\nterms of increasing IPR. In the chaotic, ballistic limit, the data correspond\nwell with universal results from random matrix theory. Deviations from\nuniversal distributions are observed due to disorder induced localization, and\nfor the weakly disordered case the data are well-described by including finite\nconductance and mean free path contributions in the framework of nonlinear\nsigma models of supersymetry.",
        "positive": "Superconducting proximity effect in semiconductor nanowires: We theoretically consider the proximity effect in\nsemiconductor-superconductor hybrid nanostructures, which are being extensively\nstudied in the context of the ongoing search for non-Abelian Majorana fermions\nin solid state systems. Specifically, we consider the dependence on the\nthickness of the semiconductor in the direction normal to the interface, a\nphysical effect that has been uncritically neglected in all prior work on the\nsubject. Quite surprisingly, we find the completely unanticipated result that\nincreasing the semiconductor thickness leads to a drastic suppression of the\ninduced superconducting gap due to proximity-induced interband coupling. As a\nresult, in the limit of strong semiconductor-superconductor coupling, the\nproximity-induced gap becomes much smaller than the bulk superconductor gap and\ndepends weakly on the interface transparency."
    },
    {
        "anchor": "Linear response theory of interacting topological insulators: Chiral surface states in topological insulators are robust against\ninteractions, non-magnetic disorder and localization, yet topology does not\nyield protection in transport. This work presents a theory of interacting\ntopological insulators in an external electric field, starting from the quantum\nLiouville equation for the many-body density matrix. Out of equilibrium,\ntopological insulators acquire a current-induced spin polarization.\nElectron-electron interactions renormalize the non-equilibrium spin\npolarization and charge conductivity, and disorder in turn enhances this\nrenormalization by a factor of two. Topological insulator phenomenology remains\nintact in the presence of interactions out of equilibrium, and an exact\ncorrespondence exists between the mathematical frameworks necessary for the\nunderstanding of the interacting and non-interacting problems.",
        "positive": "Tunable superconducting flux qubits with long coherence times: In this work, we study a series of tunable flux qubits inductively coupled to\na coplanar waveguide resonator fabricated on a sapphire substrate. Each qubit\nincludes an asymmetric superconducting quantum interference device which is\ncontrolled by the application of an external magnetic field and acts as a\ntunable Josephson junction. The tunability of the qubits is typically $\\pm 3.5$\nGHz around their central gap frequency. The measured relaxation times are\nlimited by dielectric losses in the substrate and can attain $T_{1}\\sim 8 \\mu\ns$. The echo dephasing times are limited by flux noise even at optimal points\nand reach $T_{2E}\\sim 4 \\mu s$, almost an order of magnitude longer than state\nof the art for tunable flux qubits."
    },
    {
        "anchor": "Giant and nonreciprocal second harmonic generation from layered\n  antiferromagnetism in bilayer CrI3: Layered antiferromagnetism is the spatial arrangement of ferromagnetic layers\nwith antiferromagnetic interlayer coupling. Recently, the van der Waals magnet,\nchromium triiodide (CrI3), emerged as the first layered antiferromagnetic\ninsulator in its few-layer form, opening up ample opportunities for novel\ndevice functionalities. Here, we discovered an emergent nonreciprocal second\norder nonlinear optical effect in bilayer CrI3. The observed second harmonic\ngeneration (SHG) is giant: several orders of magnitude larger than known\nmagnetization induced SHG and comparable to SHG in the best 2D nonlinear\noptical materials studied so far (e.g. MoS2). We showed that while the parent\nlattice of bilayer CrI3 is centrosymmetric and thus does not contribute to the\nSHG signal, the observed nonreciprocal SHG originates purely from the layered\nantiferromagnetic order, which breaks both spatial inversion and time reversal\nsymmetries. Furthermore, polarization-resolved measurements revealed the\nunderlying C2h symmetry, and thus monoclinic stacking order in CrI3 bilayers,\nproviding crucial structural information for the microscopic origin of layered\nantiferromagnetism. Our results highlight SHG as a highly sensitive probe that\ncan reveal subtle magnetic order and open novel nonlinear and nonreciprocal\noptical device possibilities based on 2D magnets.",
        "positive": "Shubnikov-de Haas oscillations in two-dimensional electron gas under\n  subterahertz radiation: We report on magnetotransport measurements in a two-dimensional (2D) electron\ngas subject to subterahertz radiation in the regime where Shubnikov-de Haas\noscillations (SdHO) and microwave-induced resistance oscillations (MIRO)\ncoexist over a wide magnetic field range, spanning several harmonics of the\ncyclotron resonance. Surprisingly, we find that the SdHO amplitude is modified\nby the radiation in a non-trivial way owing to the oscillatory correction which\nhas the same period and phase as MIRO. This finding challenges our current\nunderstanding of microwave photoresistance in 2D electron gas, calling for\nfuture investigations."
    },
    {
        "anchor": "Unified time-dependent perturbative relations applied to spectroscopy\n  through photo-drag current: We develop and exploit an out-of-equilibrium theory, valid in arbitrary\ndimensions, which does not require initial thermalization. It is perturbative\nwith respect to a weak time-dependent (TD) Hamiltonian term, but is\nnon-perturbative with respect to strong coupling to an electromagnetic\nenvironment, or to Coulomb or superconducting correlations. We derive unifying\nrelations between the current generated by coherent radiation or statistical\nmixture of radiations, superimposed on a dc voltage $V_{dc}$, and the\nout-of-equilibrium dc current which encodes the effects of interactions. Thus\nwe extend fully the lateral band-transmission picture, thus quantum\nsuperposition, to coherent many-body correlated states. This provides methods\nfor a determination of the carrier's charge q free from unknown parameters\nthrough the robustness of the Josephson-like frequency. Similar relations we\nhave derived for noise have allowed, recently, to determine the fractional\ncharge in the Fractional Quantum Hall Effect (FQHE) within the Jain series (M.\nKapfer et al, Science 2018). The present theory allows for breakdown of\ninversion symmetry and for asymmetric rates for emission and absorption of\nradiations. This generates a photo-ratchet effect we exploit to propose a novel\nmethod to measure the charge $q$, as well as spectroscopical analysis of the\nout-of-equilibrium dc current and the third cumulant of non-gaussian\nstatistical radiations. We apply the theory to the Tomonaga-Luttinger Liquid\n(TLL), showing a counterintuitive feature: a lorentzian pulse superimposed on\n$V_{dc}$ can reduce the current compared to its dc value, at the same $V_{dc}$,\nquestioning the terminology \"photo-assisted\". Beyond a charge current, the\ntheory applies to operators such as spin current in the spin Hall effect, or\nvoltage drop across a phase-slip Josephson junction.",
        "positive": "Generalized Hamiltonian for Kekul\u00e9 graphene and the emergence of\n  valley-cooperative Klein tunneling: We introduce a generalized Hamiltonian describing not only all topological\nphases observed experimentally in Kekul\\'e graphene (KekGr) but predicting also\nnew ones. These phases show features like a quadratic band crossing point,\nvalley splitting, or the crossing of conduction bands, typically induced by\nRashba spin-orbit interactions or Zeeman fields. The electrons in KekGr behave\nas Dirac fermions and follow pseudo-relativistic dispersion relations with\nFermi velocities, rest masses, and valley-dependent self-gating. Transitions\nbetween the topological phases can be induced by tuning these parameters. The\nmodel is applied to study the current flow in KekGr $pn$ junctions evidencing a\nnovel cooperative transport phenomenon, where Klein tunneling goes along with a\nvalley flip. These junctions act as perfect filters and polarizers of massive\nDirac fermions, which are the essential devices for valleytronics. The plethora\nof different topological phases in KekGr may also help to establish phenomena\nfrom spintronics."
    },
    {
        "anchor": "A Mechanically Tunable Quantum Dot in a Graphene Break Junction: Graphene quantum dots (QDs) are intensively studied as platforms for the next\ngeneration of quantum electronic devices. Fine tuning of the transport\nproperties in monolayer graphene QDs, in particular with respect to the\nindependent modulation of the tunnel barrier transparencies, remains\nchallenging and is typically addressed using electrostatic gating. We\ninvestigate charge transport in back-gated graphene mechanical break junctions\nand reveal Coulomb blockade physics characteristic of a single, high-quality QD\nwhen a nanogap is opened in a graphene constriction. By mechanically\ncontrolling the distance across the newly-formed graphene nanogap, we achieve\nreversible tunability of the tunnel coupling to the drain electrode by five\norders of magnitude, while keeping the source-QD tunnel coupling constant.\nThese findings indicate that the tunnel coupling asymmetry can be significantly\nmodulated with a mechanical tuning knob and has important implications for the\ndevelopment of future graphene-based devices, including energy converters and\nquantum calorimeters.",
        "positive": "Bistability and oscillatory motion of natural nano-membranes appearing\n  within monolayer graphene on silicon dioxide: The recently found material graphene is a truly two-dimensional crystal and\nexhibits, in addition, an extreme mechanical strength. This in combination with\nthe high electron mobility favours graphene for electromechanical\ninvestigations down to the quantum limit. Here, we show that a monolayer of\ngraphene on SiO2 provides natural, ultra-small membranes of diameters down to 3\nnm, which are caused by the intrinsic rippling of the material. Some of these\nnano-membranes can be switched hysteretically between two vertical positions\nusing the electric field of the tip of a scanning tunnelling microscope (STM).\nThey can also be forced to oscillatory motion by a low frequency ac-field.\nUsing the mechanical constants determined previously, we estimate a high\nresonance frequency up to 0.4 THz. This might be favorable for\nquantum-electromechanics and is prospective for single atom mass spectrometers."
    },
    {
        "anchor": "Unusual superparamagnetic behavior of Co3O4 nanoparticles: We report detailed studies on magnetic properties of Co3O4 nanoparticles of\naverage size 12.5 nm. Temperature and field dependence of magnetization, wait\ntime dependence of magnetic relaxation (aging), memory effects and temperature\ndependence of specific heat have been investigated to understand the magnetic\nbehavior of these particles. We find that the particles show some features\ncharacteristic of nanoparticle magnetism such as bifurcation of field cooled\n(FC) and zero field cooled (ZFC) susceptibilities and a slow relaxation of\nmagnetization. However, strangely, the temperature at which ZFC magnetization\npeaks coincides with the bifurcation temperature and does not shift on\napplication of magnetic fields up to 1 kOe, unlike most other nanoparticle\nsystems. Aging effects in these particles are negligible in both FC and ZFC\nprotocol and memory effects are present only in FC protocol. Our results show\nthat Co3O4 nanoparticles constitute a unique system where superparamagnetic\nblocking starts above the N\\'eel temperature, in the paramagnetic state.",
        "positive": "Formation of the $n=0$ Landau level in hybrid graphene: The minimum of 4-terminal conductance occurring at its charge neutral point\nhas proven to be a robust empirical feature of graphene, persisting with\nchanges to temperature, applied magnetic field, substrate, and layer thickness,\nthough the theoretical mechanisms involved in transport about this point --\nvanishing density of states, conventional band gap opening, and broken symmetry\nquantum Hall mobility gaps -- vary widely depending on the regime. In this\npaper, we report on observations of a regime where the 4-terminal conductance\nminimum ceases to exist: transport in monolayer graphene connected to bilayer\ngraphene during the onset of the quantum Hall effect. As monolayer and bilayer\ngraphene have distinct zero-energy Landau levels that form about the charge\nneutral point, our observations suggest that competitions between the differing\nmany-body orderings of these states as they emerge may underlie this anomalous\nconductance."
    },
    {
        "anchor": "Effective lattice Hamiltonian for monolayer MoS2 : Tailoring electronic\n  structure with perpendicular electric and magnetic fields: We propose an effective lattice Hamiltonian for monolayer MoS$_2$ in order to\ndescribe the low-energy band structure and investigate the effect of\nperpendicular electric and magnetic fields on its electronic structure. We\nderive a tight-binding model based on the hybridization of the $d$ orbitals of\nmolybdenum and $p$ orbitals of sulfur atoms and then introduce a modified\ntwo-band continuum model of monolayer MoS$_2$ by exploiting the\nquasi-degenerate partitioning method. Our theory proves that the low-energy\nexcitations of the system are no longer massive Dirac fermions. It reveals a\ndifference between electron and hole masses and provides trigonal warping\neffects. Furthermore, we predict a valley degeneracy breaking effect in the\nLandau levels. Besides, we also show that applying a gate voltage perpendicular\nto the monolayer modifies the electronic structure including the band gap and\neffective masses.",
        "positive": "Wrinkles of graphene on Ir(111): Macroscopic network ordering and\n  internal multi-lobed structure: The large-scale production of graphene monolayer greatly relies on epitaxial\nsamples which often display stress-relaxation features in the form of wrinkles.\nWrinkles of graphene on Ir(111) are found to exhibit a fairly well ordered\ninterconnecting network which is characterized by low-energy electron\nmicroscopy (LEEM). The high degree of quasi-hexagonal network arrangement for\nthe graphene aligned to the underlying substrate can be well described as a\n(non-Poissonian) Voronoi partition of a plane. The results obtained strongly\nsuggest that the wrinkle network is frustrated at low temperatures, retaining\nthe order inherited from elevated temperatures when the wrinkles interconnect\nin junctions which most often join three wrinkles. Such frustration favors the\nformation of multi-lobed wrinkles which are found in scanning tunneling\nmicroscopy (STM) measurements. The existence of multiple lobes is explained\nwithin a model accounting for the interplay of the van der Waals attraction\nbetween graphene and iridium and bending energy of the wrinkle. The presented\nstudy provides new insights into wrinkling of epitaxial graphene and can be\nexploited to further expedite its application."
    },
    {
        "anchor": "Impact of Channel Mixing on the Visibility of Two-particle\n  Interferometry in Quantum Hall Edge States: We consider a two-particle interferometer, where voltage sources applied to\nohmic contacts inject electronic excitations into a pair of copropagating edge\nchannels. We analyze the impact of channel mixing due to inter-edge tunneling\non the current noise measured at the output of the interferometer. Due to this\nmixing, the noise suppression typically expected for synchronized injecting\nsources is incomplete, thereby reducing the visibility of the interference. We\ninvestigate to which extent the impact of mixing on the noise visibility\ndepends on different shapes of the voltage drives. Furthermore, we compare a\nsimple model involving a single mixing point between the sources and the\nquantum point contact to the more realistic case of a continuous distribution\nof weak mixing points.",
        "positive": "Kerr, Faraday, and Magnetoelectric Effects in MnBi$_2$Te$_4$ Thin Films: The topological magneto-electric effect (TME) is a characteristic property of\ntopological insulators. In this article we use a simplified coupled-Dirac-cone\nelectronic structure model to theoretically evaluate the THz and far infrared\nKerr and Faraday responses of thin films of MnBi$_2$Te$_4$ with up to $N=10$\nseptuple layers with the goal of clarifying the relationship between these\nconvenient magneto-optical observable and the TME. We find that for even $N$\nthe linear Kerr and Faraday responses to an electric field vanish in the\nlow-frequency limit, even though the the magnetoelectric response is large and\napproximately quantized."
    },
    {
        "anchor": "Simultaneous detection of the spin-Hall magnetoresistance and the\n  spin-Seebeck effect in Platinum and Tantalum on Yttrium Iron Garnet: The spin-Seebeck effect (SSE) in platinum (Pt) and tantalum (Ta) on yttrium\niron garnet (YIG) has been investigated by both externally heating the sample\n(using an on-chip Pt heater on top of the device) as well as by current-induced\nheating. For SSE measurements, external heating is the most common method to\nobtain clear signals. Here we show that also by current-induced heating it is\npossible to directly observe the SSE, separate from the also present spin-Hall\nmagnetoresistance (SMR) signal, by using a lock-in detection technique. Using\nthis measurement technique, the presence of additional 2nd order signals at low\napplied magnetic fields and high heating currents is revealed. These signals\nare caused by current-induced magnetic fields (Oersted fields) generated by the\nused AC-current, resulting in dynamic SMR signals.",
        "positive": "Singular electrostatic energy of nanoparticle clusters: The binding of clusters of metal nanoparticles is partly electrostatic. We\naddress difficulties in calculating the electrostatic energy when high charging\nenergies limit the total charge to a single quantum, entailing unequal\npotentials on the particles. We show that the energy at small separation $h$\nhas a strong logarithmic dependence on $h$. We give a general law for the\nstrength of this logarithmic correction in terms of a) the energy at contact\nignoring the charge quantization effects and b) an adjacency matrix specifying\nwhich spheres of the cluster are in contact and which is charged. We verify the\ntheory by comparing the predicted energies for a tetrahedral cluster with an\nexplicit numerical calculation."
    },
    {
        "anchor": "Bridge between Abelian and Non-Abelian Fractional Quantum Hall States: We propose a scheme to construct the most prominent Abelian and non-Abelian\nfractional quantum Hall states from K-component Halperin wave functions. In\norder to account for a one-component quantum Hall system, these SU(K) colors\nare distributed over all particles by an appropriate symmetrization. Numerical\ncalculations corroborate the picture that the proposed scheme allows for a\nunification of both Abelian and non-Abelian trial wave functions in the study\nof one-component quantum Hall systems.",
        "positive": "Negative differential electrical resistance of a rotational organic\n  nanomotor: A robust nanoelectromechanical switch is proposed based upon an asymmetric\npendant moiety anchored to an organic backbone between two C60 fullerenes,\nwhich in turn are connected to gold electrodes. Ab initio density functional\ncalculations are used to demonstrate that an electric field induces rotation of\nthe pendant group, leading to a non-linear current-voltage relation. The\nnon-linearity is strong enough to lead to negative differential resistance at\nmodest source-drain voltages."
    },
    {
        "anchor": "BGO relaxation dynamics probed with heterodyne detected optical\n  transient gratings: We used optical laser pulses to create transient gratings (TGs) with sub-10\n{\\mu}m spatial periodicity in a Bismuth Germanate (310) (Bi4Ge3O12) single\ncrystal at room temperature. The TG launches phonon modes, whose dynamics were\nrevealed via forward diffraction of a third, time-delayed, heterodyne-detected\noptical pulse. Acoustic oscillations have been clearly identified in a\ntime-frequency window not covered by previous spectroscopic studies and their\ncharacteristic dynamic parameters have been measured as a function of\ntransferred momenta magnitude and direction.",
        "positive": "Resonant interaction of molecular vibrations and surface plasmon\n  polaritons: The weak coupling regime: Adjusting the free-electron concentration, the surface plasmon frequency of\nthe semiconductor ZnOGa is tuned into resonance with the molecular vibrations\nof the n-alkane tetracontane. Closed molecular films deposited on the\nsemiconductor's surface in the monolayer regime generate distinct signatures in\ntotal-attenuated-reflection spectra at the frequencies of the symmetric and\nasymmetric stretching vibrations of the CH2 group. Their line shape undergoes\nprofound changes from absorptive to dispersive and even anti-resonance behavior\nwhen moving along the surface- plasmon dispersion by the angel of incidence. We\ndemonstrate that this line shape diversity results from a phase-sensitive\nperturbation of the surface-plasmon-polariton generation at the molecule/metal\ninterface."
    },
    {
        "anchor": "Skyrmion flow in periodically modulated channels: Magnetic skyrmions, topologically stabilized chiral magnetic textures with\nparticle-like properties have so far primarily been studied statically. Here,\nwe experimentally investigate the dynamics of skyrmion ensembles in metallic\nthin film conduits where they behave as quasi-particle fluids. By exploiting\nour access to the full trajectories of all fluid particles by means of\ntime-resolved magneto-optical Kerr microscopy, we demonstrate that boundary\nconditions of skyrmion fluids can be tuned by modulation of the channel\ngeometry. We observe as a function of channel width deviations from classical\nflow profiles even into the no- or partial-slip regime. Unlike conventional\ncolloids, the skyrmion Hall effect can also introduce transversal\nflow-asymmetries and even local motion of single skyrmions against the driving\nforce which we explore with particle-based simulations, demonstrating the\nunique properties of skyrmion liquid flow that uniquely deviates from\npreviously known behavior of other quasi-particles.",
        "positive": "Generation of gigahertz frequency surface acoustic waves in YIG/ZnO\n  heterostructures: We study surface acoustic waves (SAWs) in yttrium iron garnet (YIG)/zinc\noxide (ZnO) heterostructures, comparing the results of a computationally\nlightweight analytical model with time-resolved micro-focused Brillouin light\nscattering data. Interdigital transducers (IDTs), with operational frequencies\nin the gigahertz regime, were fabricated on 50 and 100nm thin films of YIG\nprior to sputter deposition of 830nm and 890nm films of piezoelectric ZnO. We\nfind good agreement between our analytical model and micro-focused Brillouin\nlight scattering data of the IDT frequency response and SAW group velocity,\nwith clear differentiation between the Rayleigh and Sezawa-like modes. This\nwork paves the way for the study of SAW-spin wave (SW) interactions in low SW\ndamping YIG, with the possibility of a method for future energy-efficient SW\nexcitation."
    },
    {
        "anchor": "Influence of the electron-phonon interfacial conductance on the thermal\n  transport at metal/dielectric interfaces: Thermal boundary conductance at a metal-dieletric interface is a quantity of\nprime importance for heat management at the nanoscale. While the boundary\nconductance is usually ascribed to the coupling between metal phonons and\ndielectric phonons, in this work we examine the influence of a direct coupling\nbetween the metal electrons and the dielectric phonons. The effect of electron-\nphonon processes is generally believed to be resistive, and tends to decrease\nthe overall thermal boundary conductance as compared to the phonon-phonon\nconductance {\\sigma}p . Here, we find that the effect of a direct coupling\n{\\sigma}e is to enhance the effective thermal conductance, between the metal\nand the dielectric. Resistive effects turn out to be important only for thin\nfilms of metals having a low electron-phonon coupling strength. Two approaches\nare explored to reach these conclusions. First, we present an analytical\nsolution of the two-temperature model to compute the effective conductance\nwhich account for all the relevant energy channels, as a function of {\\sigma}e\n, {\\sigma}p and the electron-phonon coupling factor G. Second, we use numerical\nresolution to examine the influence of {\\sigma}e on two realistic cases: gold\nfilm on silicon or silica substrates. We point out the implications for the\ninterpretation of time-resolved thermoreflectance experiments.",
        "positive": "Shot Noise in Anyonic Mach-Zehnder Interferometer: We show how shot noise in an electronic Mach-Zehnder interferometer in the\nfractional quantum Hall regime probes the charge and statistics of quantum Hall\nquasiparticles. The dependence of the noise on the magnetic flux through the\ninterferometer allows for a simple way to distinguish Abelian from non-Abelian\nquasiparticle statistics. In the Abelian case, the Fano factor (in units of the\nelectron charge) is always lower than unity. In the non-Abelian case, the\nmaximal Fano factor as a function of the magnetic flux exceeds one."
    },
    {
        "anchor": "Interplay of spin-orbit and hyperfine interactions in dynamical nuclear\n  polarization in semiconductor quantum dots: We theoretically study the interplay of spin-orbit and hyperfine interactions\nin dynamical nuclear polarization in two-electron semiconductor double quantum\ndots near the singlet $(S)$ - triplet $(T_+)$ anticrossing. The goal of the\nscheme under study is to extend the singlet $(S)$ - triplet $(T_0)$ qubit\ndecoherence time $T_2^{*}$ by dynamically transferring the polarization from\nthe electron spins to the nuclear spins. This polarization transfer is achieved\nby cycling the electron spins over the $S-T_+$ anticrossing. Here, we\ninvestigate, both quantitatively and qualitatively, how this hyperfine mediated\ndynamical polarization transfer is influenced by the Rashba and Dresselhaus\nspin-orbit interaction. In addition to $T_2^*$, we determine the singlet return\nprobability $P_s$, a quantity that can be measured in experiments. Our results\nsuggest that the spin-orbit interaction establishes a mechanism that can\npolarize the nuclear spins in the opposite direction compared to hyperfine\nmediated nuclear spin polarization. In materials with relatively strong\nspin-orbit coupling, this interplay of spin-orbit and hyperfine mediated\nnuclear spin polarizations prevents any notable increase of the $S-T_0$ qubit\ndecoherence time $T_2^{*}$.",
        "positive": "Self-consistent study of electron confinement to metallic thin films on\n  solid surfaces: We present a method for density-functional modeling of metallic overlayers\ngrown on metallic supports. It offers a tool to study nanostructures and\ncombines the power of self-consistent pseudopotential calculations with the\nsimplicity of a one-dimensional approach. The model is applied to Pb layers\ngrown on the Cu(111) surface. More specifically, Pb is modeled as stabilized\njellium and the Cu(111) substrate is represented by a one-dimensional\npseudopotential that reproduces experimental positions of both the Cu Fermi\nlevel and the energy gap of the band structure projected along the (111)\ndirection. The model is used to study the quantum well states in the Pb\noverlayer. Their analysis gives the strength of the electron confinement\nbarriers at the interface and at the surface facing the vacuum. Our results and\nanalysis support the interpretation of the quantum well state spectra measured\nby the scanning tunneling spectroscopy."
    },
    {
        "anchor": "Radiative quantum efficiency in an InAs/AlSb intersubband transition: The quantum efficiency of an electroluminescent intersubband emitter based on\nInAs/AlSb has been measured as a function of the magnetic field up to 20T. Two\nseries of oscillations periodic in 1/B are observed, corresponding to the\nelastic and inelastic scattering of electrons of the upper state of the\nradiative transitions. Experimental results are accurately reproduced by a\ncalculation of the excited state lifetime as a function of the applied magnetic\nfield. The interpretation of these data gives an exact measure of the relative\nweight of the scattering mechanisms and allows the extraction of material\nparameters such as the energy dependent electron effective mass and the optical\nphonon energy.",
        "positive": "Chiral kinetic theory of anomalous transport induced by torsion: In Weyl semimetals subjected to torsion, there are two different kinds of\nchirality: i) the (coordinate-space) shape of the twisted crystal is chiral,\nand ii) the momentum space contains chiral quasi-particles. Here we construct a\ngeneral kinetic theory of anomalous transport using the phase space (coordinate\nand momentum spaces combined) Berry curvature induced by torsion in Weyl\nsystems. We describe how torsion generates the chiral chemical potential, and\nthus leads to the Chiral Magnetic Effect (CME) in the presence of a background\nmagnetic field. We propose to measure the CME current induced by the torsion as\na way to detect the anomalous coupling between the coordinate-space and\nmomentum-space chiralities."
    },
    {
        "anchor": "Thermoelectric terahertz photodetectors based on selenium-doped black\n  phosphorus flakes: Chemical doping of bulk black phosphorus is a well-recognized way to reduce\nsurface oxidation and degradation. Here, we report on the fabrication of\nterahertz frequency detectors consisting of an antenna-coupled field-effect\ntransistor (FET) with an active channel of Se-doped black phosphorus. Our\ndevices show a maximum room-temperature hole mobility of 1780 cm2V-1s-1 in a\nSiO2-encapsulated FET. A room-temperature responsivity of 3 V/W was observed,\nwith a noise-equivalent power of 7 nWHz-1/2 at 3.4 THz, comparable with the\nstate-of-the-art room-temperature photodetectors operating at the same\nfrequency. Therefore, the inclusion of Se dopants in the growth process of\nblack phosphorus crystals enables the optimization of the transport and optical\nperformances of FETs in the far-infrared with a high potential for the\ndevelopment of BP-based electro-optical devices. We also demonstrate that the\nflake thickness can be tuned according to the target application. Specifically,\nthicker flakes (>80 nm) are suitable for applications in which high mobility\nand high speed are essential, thinner flakes (<10 nm) are more appropriate for\napplications requiring high on/off ratios, while THz photodetection is optimal\nwith flakes 30-40 nm thick, due to the larger carrier density tunability.",
        "positive": "Energy loss spectroscopy of Buckminster C60 with twisted electrons:\n  Influence of orbital angular momentum transfer on plasmon generation: Recent experimental progress in creating and controlling singular electron\nbeams that carry orbital angular momentum allows for new types of local\nspectroscopies. We theoretically investigate the twisted-electron energy loss\nspectroscopy (EELS) from the C60 fullerene. Of particular interest are the\nstrong multipolar collective excitations and their selective response to the\norbital angular momentum of the impinging electron beam. Based on ab-initio\ncalculations for the collective response we compute EELS signals with twisted\nelectron beams and uncover the interplay between the plasmon polarity and the\namount of angular momentum transfer."
    },
    {
        "anchor": "Spin-flip process through a quantum dot coupled to ferromagnetic\n  electrodes: We study the spin-dependent transport through a quantum dot coupled to two\nferromagnetic electrodes using the equation of motion method for the\nnonequilibrium Green's functions. Our results show that the conductance and the\ndensity of states (DOS) are strongly dependent on the configurations of the\nmagnetic electrodes. In parallel configuration of magnetic electrodes the\nconductance is affected by the spin-flip process and the Coulomb repulsion on\nthe dot. The Kondo peak for spin-dependent transport is splitted into two peaks\nby the spin-flip process. The locations of the two peaks are symmetric about no\nspin-flip peak and the separation of the splitting is dependent on the strength\nof the spin-flip parameter $R$. This effect may be useful to realize the\nspin-filter device.",
        "positive": "Photon and magnetic field controlled electron transport of a\n  multiply-resonant photon-cavity double quantum dot system: We study electron transport through double quantum dots (DQD) coupled to a\ncavity with a single photon mode. The DQD is connected to two electron\nreservoirs, and the total system is under an external perpendicular magnetic\nfield. The DQD system exhibits a complex multi-level energy spectrum. By\nvarying the photon energy, several anti-crossings between photon dressed\nelectron states of the DQD-cavity system are found at low strength of the\nmagnetic field. The anti-crossings are identified as multiple Rabi resonances\narising from the photon exchange between these states. As the results, a dip in\nthe current is seen caused by the multiple Rabi resonances. By increasing the\nstrength of the external magnetic field, a dislocation of the current dip to a\nlower photon energy is found and the current dip can be diminished. The\ninterplay of the strength of the magnetic field and the geometry of the states\nthe DQD system can weaken the multiple Rabi resonances in which the exchange of\nphoton between the anti-crossings is decreased. We can therefore confirm that\nthe electron transport behavior in the DQD-cavity system can be controlled by\nmanipulating the external magnetic field and the photon cavity parameters."
    },
    {
        "anchor": "Renormalization of spin-rotation coupling: We predict the enhancement of the spin-rotation coupling due to the interband\nmixing. The Bloch wavefunctions in the presence of mechanical rotation are\nconstructed with the generalized crystal momentum which includes a gauge\npotential arising from the rotation. Using the eight- band Kane model, the\nrenormalized spin-rotation coupling is explicitly obtained. As a result of the\nrenormalization, the rotational Doppler shift in electron spin resonance and\nthe mechanical torque on an electron spin will be strongly modulated.",
        "positive": "Spin detection at elevated temperatures using a driven double quantum\n  dot: We consider a double quantum dot in the Pauli blockade regime interacting\nwith a nearby single spin. We show that under microwave irradiation the average\nelectron occupations of the dots exhibit resonances that are sensitive to the\nstate of the nearby spin. The system thus acts as a spin meter for the nearby\nspin. We investigate the conditions for a non-demolition read-out of the spin\nand find that the meter works at temperatures comparable to the dot charging\nenergy and sensitivity is mainly limited by the intradot spin relaxation."
    },
    {
        "anchor": "Highly tunable exchange-only singlet-only qubit in a GaAs triple quantum\n  dot: We propose an implementation of a singlet-only spin qubit in a GaAs-based\ntriple quantum dot with a (1,4,1) charge occupation. In the central\nmulti-electron dot, the interplay between Coulomb interaction and an\nout-of-plane magnetic field creates an energy spectrum with a tunable\nsinglet-triplet splitting, which can be exploited to create a six-particle\nsinglet-only qubit with a qubit splitting that can straightforwardly be tuned\nover tens of $\\mu$eV by adjusting the external magnetic field. We confirm the\nfull exchange-based electric control of the qubit and demonstrate its superior\ncoherence properties due to its singlet-only nature.",
        "positive": "Cascade of multi-electron bubble phases in monolayer graphene at high\n  Landau level filling: The phase diagram of an interacting two-dimensional electron system in a high\nmagnetic field is enriched by the varying form of the effective Coulomb\ninteraction, which depends strongly on the Landau level index. While the\nfractional quantum Hall states that dominate in the lower energy Landau levels\nhave been explored experimentally in a variety of two-dimensional systems, much\nless work has been done to explore electron solids owing to their subtle\ntransport signatures and extreme sensitivity to disorder. Here we use chemical\npotential measurements to map the phase diagram of electron solid states in\n$N=2$, $N=3$, and $N=4$ Landau levels in monolayer graphene. Direct comparison\nbetween our data and theoretical calculations reveals a cascade of\ndensity-tuned phase transitions between electron bubble phases up to two, three\nor four electrons per bubble in the N=2, 3 and 4 Landau levels respectively.\nFinite temperature measurements are consistent with melting of the solids for\nT$\\approx$1K."
    },
    {
        "anchor": "Classification of crystalline topological semimetals with an application\n  to Na$_3$Bi: Topological phases can not only be protected by internal symmetries (e.g.,\ntime-reversal symmetry), but also by crystalline symmetries, such as reflection\nor rotation symmetry. Recently a complete topological classification of\nreflection symmetric insulators, superconductors, nodal semimetals, and nodal\nsuperconductors has been established. In this article, after a brief review of\nthe classification of reflection-symmetry-protected semimetals and nodal\nsuperconductors, we discuss an example of a three-dimensional topological Dirac\nsemimetal, which exhibits time-reversal symmetry as well as reflection and\nrotation symmetries. We compute the surface state spectrum of this Dirac\nsemimetal and identify the crystal lattice symmetries that lead to the\nprotection of the surface states. We discuss the implications of our findings\nfor the stability of the Fermi arc surface states of the Dirac material\nNa$_3$Bi. Our analysis suggests that the Fermi arc of Na$_3$Bi is gapped except\nat time-reversal invariant surface momenta, which is in agreement with recent\nphotoemission measurements.",
        "positive": "High-harmonic generation in a quantum electron gas trapped in a\n  nonparabolic and anisotropic well: An effective self-consistent model is derived and used to study the dynamics\nof an electron gas confined in a nonparabolic and anisotropic quantum well.\nThis approach is based on the equations of quantum hydrodynamics, which\nincorporate quantum and nonlinear effects in an approximate fashion. The\neffective model consists of a set of six coupled differential equations\n(dynamical system) for the electric dipole and the size of the electron gas.\nUsing this model we show that: (i) High harmonic generation is related to the\nappearance of chaos in the phase space, as attested by related Poincar\\'e\nsections; (ii) Higher order harmonics can be excited efficiently and with\nrelatively weak driving fields by making use of chirped electromagnetic waves."
    },
    {
        "anchor": "Tunable Circular Photogalvanic and Photovoltaic Effect in 2D Tellurium\n  with Different Chirality: Chirality arises from the asymmetry of matters, where two counterparts are\nthe mirror image of each other. The interaction between circular-polarization\nlight and quantum materials is enhanced in chiral space groups due to the\nstructural chirality. Tellurium (Te) possesses the simplest chiral crystal\nstructure, with Te atoms covalently bonded into a spiral atomic chain (left- or\nright-handed) with a periodicity of three. Here, we investigate the tunable\ncircular photo-electric responses in 2D Te field-effect transistor with\ndifferent chirality, including the longitudinal circular photogalvanic effect\ninduced by the radial spin texture (electron-spin polarization parallel to the\nelectron momentum direction) and the circular photovoltaic induced by the\nchiral crystal structure (helical Te atomic chains). Our work demonstrates the\ncontrollable manipulation of the chirality degree of freedom in materials.",
        "positive": "Phase Diffusion in Single-Walled Carbon Nanotube Josephson Transistors: We investigate electronic transport in Josephson junctions formed by\nsingle-walled carbon nanotubes coupled to superconducting electrodes. We\nobserve enhanced zero-bias conductance (up to 10e^2/h) and pronounced\nsub-harmonic gap structures in differential conductance, which arise from the\nmultiple Andreev reflections at superconductor/nanotube interfaces. The\nvoltage-current characteristics of these junctions display abrupt switching\nfrom the supercurrent branch to resistive branch, with a gate-tunable switching\ncurrent ranging from 50 pA to 2.3 nA. The finite resistance observed on the\nsupercurrent branch and the magnitude of the switching current are in good\nagreement with calculation based on the model of classical phase diffusion."
    },
    {
        "anchor": "Ring-Like Solitons in Plasmonic Fiber Waveguide Composed of\n  Metal-Dielectric Multilayers: We design a plasmonic fiber waveguide (PFW) composed of coaxial cylindrical\nmetal-dielectric multilayers in nanoscale, and constitute the corresponding\ndynamical equations describing the modes of propagation in the PFW with the\nKerr nonlinearity in the dielectric layers. The physics is connected to the\ndiscrete matrix nonlinear Schr\\\"{o}dinger equations, from which the highly\nconfined ring-like solitons in scale of subwavelength are found both for the\nvisible light and the near-infrared light in the self-defocusing condition.\nMoreover, the confinement could be further improved when increasing the\nintensity of the input light due to the cylindrical symmetry of the PFW, which\nmeans both the width and the radius of the ring are reduced.",
        "positive": "Pushing the limit of quantum transport simulations: Simulations of quantum transport in coherent conductors have evolved into\nmature techniques that are used in fields of physics ranging from electrical\nengineering to quantum nanoelectronics and material science. The most efficient\ngeneral-purpose algorithms have a computational cost that scales as $L^{6 \\dots\n7}$ in 3D, which on the one hand is a substantial improvement over older\nalgorithms, but on the other hand still severely restricts the size of the\nsimulation domain, limiting the usefulness of simulations through strong\nfinite-size effects. Here, we present a novel class of algorithms that, for\ncertain systems, allows to directly access the thermodynamic limit. Our\napproach, based on the Green's function formalism for discrete models, targets\nsystems which are mostly invariant by translation, i.e. invariant by\ntranslation up to a finite number of orbitals and/or quasi-1D electrodes and/or\nthe presence of edges or surfaces. Our approach is based on an automatic\ncalculation of the poles and residues of series expansions of the Green's\nfunction in momentum space. This expansion allows to integrate analytically in\none momentum variable. We illustrate our algorithms with several applications:\ndevices with graphene electrodes that consist of half an infinite sheet;\nFriedel oscillation calculations of infinite 2D systems in presence of an\nimpurity; quantum spin Hall physics in presence of an edge; the surface of a\nWeyl semi-metal in presence of impurities and electrodes connected to the\nsurface. In this last example, we study the conduction through the Fermi arcs\nof the topological material and its resilience to the presence of disorder. Our\napproach provides a practical route for simulating 3D bulk systems or surfaces\nas well as other setups that have so far remained elusive."
    },
    {
        "anchor": "Evolution of the bilayer nu = 1 quantum Hall state under charge\n  imbalance: We use high-mobility bilayer hole systems with negligible tunneling to\nexamine how the bilayer nu = 1 quantum Hall state evolves as charge is\ntransferred from one layer to the other at constant total density. We map\nbilayer nu = 1 state stability versus imbalance for five total densities\nspanning the range from strongly interlayer coherent to incoherent. We observe\ncompetition between single-layer correlations and interlayer coherence. Most\nsignificantly, we find that bilayer systems that are incoherent at balance can\ndevelop spontaneous interlayer coherence with imbalance, in agreement with\nrecent theoretical predictions.",
        "positive": "Resistivity scaling in metallic thin films and nanowires due to grain\n  boundary and surface roughness scattering: A modeling approach, based on an analytical solution of the semiclassical\nmulti-subband Boltzmann transport equation, is presented to study resistivity\nscaling in metallic thin films and nanowires due to grain boundary and surface\nroughness scattering. While taking into account the detailed statistical\nproperties of grains, roughness and barrier material as well as the metallic\nband structure and quantum mechanical aspects of scattering and confinement,\nthe model does not rely on phenomenological fitting parameters."
    },
    {
        "anchor": "Excitation Spectrum and Stability from a Filled Landau Level in Rotating\n  Dipolar Fermi Gases: We apply the equation-of-motion method to study the collective excitation\nspectrum from a filled Landau level in rotating dipolar Fermi gases. The\npredicted excitation spectrum of rotating dipolar Fermi gases can exhibit a\nroton-minimum character. This roton character is tunable by varying the dipole\ninteraction strength and confining potential. An increase of the dipole\ninteraction strength makes the roton minimum becoming zero, and the system\nbecomes unstable. We also obtain a condition for the dynamical stability of\nrotating dipolar Fermi gases.",
        "positive": "Shapiro Steps for Skyrmion Motion on a Washboard Potential with\n  Longitudinal and Transverse ac Drives: We numerically study the behavior of two-dimensional skyrmions in the\npresence of a quasi-one-dimensional sinusoidal substrate under the influence of\nexternally applied dc and ac drives. In the overdamped limit, when both dc and\nac drives are aligned in the longitudinal direction parallel to the direction\nof the substrate modulation, the velocity-force curves exhibit classic Shapiro\nstep features when the frequency of the ac drive matches the washboard\nfrequency that is dynamically generated by the motion of the skyrmions over the\nsubstrate, similar to previous observations in superconducting vortex systems.\nIn the case of skyrmions, the additional contribution to the skyrmion motion\nfrom a non-dissipative Magnus force shifts the location of the locking steps to\nhigher dc drives, and we find that the skyrmions move at an angle with respect\nto the direction of the dc drive. For a longitudinal dc drive and a\nperpendicular or transverse ac drive, the overdamped system exhibits no Shapiro\nsteps; however, when a finite Magnus force is present we find pronounced\ntransverse Shapiro steps along with complex two-dimensional periodic orbits of\nthe skyrmions in the phase-locked regimes. Both the longitudinal and transverse\nac drives produce locking steps whose widths oscillate with increasing ac drive\namplitude. We examine the role of collective skyrmion interactions and find\nthat additional fractional locking steps occur for both longitudinal and\ntransverse ac drives. At higher skyrmion densities, the system undergoes a\nseries of dynamical order-disorder transitions, with the skyrmions forming a\nmoving solid on the phase locking steps and a fluctuating dynamical liquid in\nregimes between the steps."
    },
    {
        "anchor": "Hydrodynamic Inverse Faraday Effect in Two Dimensional Electron Liquid: We show that a small conducting object, such as a nanosphere or a nanoring,\nembedded into or placed in the vicinity of the two-dimensional electron liquid\n(2DEL) and subjected to a circularly polarized electromagnetic radiation\ninduces ``twisted'' plasmonic oscillations in the adjacent 2DEL. The\noscillations are rectified due to the hydrodynamic nonlinearities leading to\nthe helicity sensitive circular dc current and to a magnetic moment. This\nhydrodynamic inverse Faraday effect (HIFE) can be observed at room temperature\nin different materials. The HIFE is dramatically enhanced in a periodic array\nof the nanospheres forming a resonant plasmonic coupler. Such a coupler exposed\nto a circularly polarized wave converts the entire 2DEL into a vortex state.\nHence, the twisted plasmonic modes support resonant plasmonic-enhanced\ngate-tunable optical magnetization. Due to the interference of the plasmonic\nand Drude contributions, the resonances have an asymmetric Fano-like shape.\nThese resonances present a signature of the 2DEL properties not affected by\ncontacts and interconnects and, therefore, providing the most accurate\ninformation about the 2DEL properties. In particular, the widths of the\nresonances encode direct information about the momentum relaxation time and\nviscosity of the 2DEL.",
        "positive": "Confined free-electrons in an applied electric field: Discontinuous\n  electron density: We consider free electrons in rectangular quantum dots, with either hard wall\nboundary conditions or anharmonic confinement. In both cases, due to finite\nsize effects, a homogeneous electric field applied along one of the rectangular\naxis is shown to induce abrupt changes in the electron density, parallel and\nperpendicularly to the field direction: the electron density jumps from one\nconfiguration to another. Making use of this property, we propose a purely\nelectrical mechanism to control the magnitude of the effective exchange\ncoupling between two quantum dots. This system has been proposed recently as a\nquantum gate for quantum computation."
    },
    {
        "anchor": "Molecular junctions in the Coulomb blockade regime: rectification and\n  nesting: Quantum transport through single molecules is very sensitive to the strength\nof the molecule-electrode contact. Here, we investigate the behavior of a model\nmolecular junction weakly coupled to external electrodes in the case where\ncharging effects do play an important role (Coulomb blockade regime). As a\nminimal model we consider a molecular junction with two spatially separated\ndonor and acceptor sites. Depending on their mutual coupling to the electrodes,\nthe resulting transport observables show well defined features such as\nrectification effects in the I-V characteristics and nesting of the stability\ndiagrams. To be able to accomplish these results, we have developed a theory\nwhich allows to explore the charging regime via the nonequilibrium Green\nfunction formalism parallel to the widely used master equation technique. Our\nresults, beyond their experimental relevance, offer a transparent framework for\nthe systematic and modular inclusion of a richer physical phenomenology.",
        "positive": "Ab initio theory of negatively charged boron vacancy qubit in hBN: Highly correlated orbitals coupled with phonons in two-dimension are\nidentified for paramagnetic and optically active boron vacancy in hexagonal\nboron nitride by first principles methods which are responsible for recently\nobserved optically detected magnetic resonance signal. We report ab initio\nanalysis of the correlated electronic structure of this center by density\nmatrix renormalization group and Kohn-Sham density functional theory methods.\nBy establishing the nature of the bright and dark states as well as the\nposition of the energy levels, we provide a complete description of the\nmagneto-optical properties and corresponding radiative and non-radiative routes\nwhich are responsible for the optical spin polarization and spin dependent\nluminescence of the defect. Our findings pave the way toward advancing the\nidentification and characterization of room temperature quantum bits in\ntwo-dimensional solids."
    },
    {
        "anchor": "Charge transport in graphene with resonant scatterers: The full counting statistics for the charge transport through an undoped\ngraphene sheet in the presence of strong potential impurities is studied.\nTreating the scattering off the impurity in the s-wave approximation, we\ncalculate the impurity correction to the cumulant generating function. This\ncorrection is universal provided the impurity strength is tuned to a resonant\nvalue. In particular, the conductance of the sample acquires a correction of\n16e^2/(pi^2 h) per resonant impurity.",
        "positive": "Extremal transmission and beating effect of acoustic wave in\n  two-dimensional sonic crystal: The extremal transmission of acoustic wave near the Dirac point in\ntwo-dimensional (2D) sonic crystal (SC), being inversely proportional to the\nthickness of sample, has been demonstrated experimentally for the first time.\nSome unusual beating effects have been observed experimentally when the\nacoustic pulse transport through the 2D SC slabs. Such phenomena are completely\ndifferent from the oscillations of the wave in a slab or cavity originating\nfrom the interface reflection or Fabry-Perot effect. They can be regarded as\nacoustic analogue to Zitterbewegung of relativistic electron. The physical\norigination for the phenomenon has been analyzed."
    },
    {
        "anchor": "Silicite: the layered allotrope of silicon: Based on first-principles calculation we predict two new thermodynamically\nstable layered-phases of silicon, named as silicites, which exhibit strong\ndirectionality in the electronic and structural properties. As compared to\nsilicon crystal, they have wider indirect band gaps but also increased\nabsorption in the visible range making them more interesting for photovoltaic\napplications. These stable phases consist of intriguing stacking of dumbbell\npatterned silicene layers having trigonal structure with $\\sqrt{3} \\times\n\\sqrt{3}$ periodicity of silicene and have cohesive energies smaller but\ncomparable to that of the cubic diamond silicon. Our findings also provide\natomic scale mechanisms for the growth of multilayer silicene as well as\nsilicites.",
        "positive": "Observation of topological surface state in a superconducting material: The discovery of topological insulator phase has ignited massive research\ninterests in novel quantum materials. Topological insulators with\nsuperconductivity further invigorate the importance of materials providing the\nplatform to study the interplay between these two unique states. However, the\ncandidates of such materials are rare. Here, we report a systematic\nangle-resolved photoemission spectroscopy (ARPES) study of a superconducting\nmaterial CaBi2 [Tc = 2 K], corroborated by the first principles calculations.\nOur study reveals the presence of Dirac cones with a topological protection in\nthis system. Systematic topological analysis based on symmetry indicator shows\nthe presence of weak topological indices in this material. Furthermore, our\ntransport measurements show the presence of large magnetoresistance in this\ncompound. Our results indicate that CaBi2 could potentially provide a material\nplatform to study the interplay between superconductivity and topology."
    },
    {
        "anchor": "Measuring the randomness of micro and nanostructure spatial\n  distributions: Effects of Scanning Electron Microscope image processing and\n  analysis: The quantitative characterization of the degree of randomness and aggregation\nof surface micro and nanostructures is critical to evaluate their effects on\ntargeted functionalities. To this end, the methods of Point Pattern Analysis\n(PPA), largely used in ecology and medical imaging, seem to provide a powerful\ntoolset. However, the application of these techniques requires the extraction\nof the point pattern of nanostructures from their microscope images. In this\nwork, we address the issue of the impact that Scanning Electron Microscope\n(SEM) image processing may have on the fundamental metric of PPA, i.e. the\nNearest Neighbour Index (NNI). Using as examples two typical SEM images of\npolymer micro- and nanostructures taken from secondary and backscattered\nelectrons, we report the effects of the a) noise filtering and b) binarization\nthreshold on the value of NNI as well as the impact of the image finite size\neffects. Based on these results, we draw conclusions for the safe choice of SEM\nsettings to provide accurate measurement of nanostructure randomness through\nNNI estimation.",
        "positive": "Helical Fermi arcs and surface states in time-reversal invariant Weyl\n  semimetals: Weyl semimetals are gapless three-dimensional topological materials where two\nbands touch at even number of points in the Brillouin zone. In this work we\nstudy a zincblende lattice model realizing a time-reversal invariant Weyl\nsemimetal. The bulk dynamics is decribed by twelve helical Weyl nodes. Surface\nstates form a peculiar quasi two-dimensional helical metal fundamentally\ndifferent from the Dirac form typical for topological insulators. Allowed\ndirection of velocity and spin of low-energy surface excitations are locked to\nthe cubic symmetry axes. The studied system illustrates general properties of\nsurface states in systems with common crystal symmetries."
    },
    {
        "anchor": "Scaling behavior of the spin pumping effect in ferromagnet/platinum\n  bilayers: We systematically measured the DC voltage V_ISH induced by spin pumping\ntogether with the inverse spin Hall effect in ferromagnet/platinum bilayer\nfilms. In all our samples, comprising ferromagnetic 3d transition metals,\nHeusler compounds, ferrite spinel oxides, and magnetic semiconductors, V_ISH\ninvariably has the same polarity. V_ISH furthermore scales with the\nmagnetization precession cone angle with a universal prefactor, irrespective of\nthe magnetic properties, the charge carrier transport mechanism or type. These\nfindings quantitatively corroborate the present theoretical understanding of\nspin pumping in combination with the inverse spin Hall effect.",
        "positive": "Optical spin Hall effect pattern switching in polariton condensates in\n  organic single-crystal microbelts: Topological polaritons, combining the robustness of the topological protected\nedge states to defects and disorder with the strong nonlinear properties of\npolariton bosons, represent an excellent platform to investigate novel photonic\ntopological phases. In this work, we demonstrated the optical spin Hall effect\n(OSHE) and its symmetry switching in the exciton-polariton regime of pure\nDPAVBi crystals. Benefiting from the photonic Rashba-Dresselhaus spin-orbit\ncoupling in organic crystals, we observed the separation of left- and\nright-circularly-polarized polariton emission in two-dimensional momentum space\nand real space, a signature of the OSHE. Above the lasing threshold, the OSHE\npattern changes due to transverse quantization in the microbelt. This device\nwithout superlattice structure has great potential applications in topological\npolaritonics, such as information transmission, photonic integrated chips and\nquantum information."
    },
    {
        "anchor": "Low-Frequency Electronic Noise in Exfoliated Quasi-1D TaSe3 van Der\n  Waals Nanowires: We report results of investigation of the low-frequency electronic excess\nnoise in quasi-1D nanowires of TaSe3 capped with quasi-2D h-BN layers.\nSemi-metallic TaSe3 is a quasi-1D van der Waals material with exceptionally\nhigh breakdown current density. It was found that TaSe3 nanowires have lower\nlevels of the normalized noise spectral density, compared to carbon nanotubes\nand graphene. The temperature-dependent measurements revealed that the\nlow-frequency electronic 1/f noise becomes the 1/f^2-type as temperature\nincreases to about 400 K, suggesting the onset of electromigration (f is the\nfrequency). Using the Dutta- Horn random fluctuation model of the electronic\nnoise in metals we determined that the noise activation energy for quasi-1D\nTaSe3 nanowires is approximately E_P=1.0 eV. In the framework of the empirical\nnoise model for metallic interconnects, the extracted activation energy,\nrelated to electromigration, is E_A=0.88 eV, consistent with that for Cu and Al\ninterconnects. Our results shed light on the physical mechanism of\nlow-frequency 1/f noise in quasi-1D van der Waals semi-metals and suggest that\nsuch material systems have potential for ultimately downscaled local\ninterconnect applications.",
        "positive": "Experimental Discovery of Topological Surface States - A New Type of 2D\n  Electron Systems (Review Article): Topological Surface States (TSS) represent new types of two dimensional\nelectron systems with novel and unprecedented properties distinct from any\nquantum Hall-like or spin-Hall effects. Their Z$_2$ topological order can be\nrealized at room temperatures without magnetic fields and they can be turned\ninto magnets, exotic superconductors or Kondo insulators leading to worldwide\ninterest and activity in the topic. We review the basic concepts defining such\ntopological matter and the experimental discovery via the key experimental\nprobe that revealed the Z$_2$ topological order in the bulk of these spin-orbit\ninteraction dominated insulators for the first time. This review focuses on the\nkey results that demonstrated the fundamental Z$_2$ topological properties such\nas spin-momentum locking, non-trivial Berry's phases, mirror Chern number,\nabsence of backscattering, bulk-boundary correspondence (topology), protection\nby time-reversal and other discrete (mirror) symmetries and their remarkable\npersistence up to the room temperature elaborating on results first briefly\ndiscussed in an early review by M.Z. Hasan and C.L. Kane [Rev. of Mod. Phys.,\n82, 3045 (2010)]. Additionally, key results on broken symmetry phases such as\nquantum magnetism and superconductivity induced in topological materials are\nbriefly discussed. Topological insulators beyond the Z$_2$ classification such\nas Topological Crystalline Insulators (TCI) are discussed based on their spin\nproperties (mirror Chern invariants). The experimental methodologies detailed\nhere have been used in most of the subsequent studies of Z$_2$ topological\nphysics in almost all bulk topological insulator materials to this date."
    },
    {
        "anchor": "Role of spin-transfer torques on synchronization and resonance phenomena\n  in stochastic magnetic oscillators: A theoretical study on how synchronization and resonance-like phenomena in\nsuperparamagnetic tunnel junctions can be driven by spin-transfer torques is\npresented. We examine the magnetization of a superparamagnetic free layer that\nreverses randomly between two well-defined orientations due to thermal\nfluctuations, acting as a stochastic oscillator. When subject to an external ac\nforcing this system can present stochastic resonance and noise-enhanced\nsynchronization. We focus on the roles of the mutually perpendicular\ndamping-like and field-like torques, showing that the response of the system is\nvery different at low and high-frequencies. We also demonstrate that the\nfield-like torque can increase the efficiency of the current-driven forcing,\nspecially at sub-threshold electric currents. These results can be useful for\npossible low-power, more energy efficient, applications.",
        "positive": "Shot-noise and conductance measurements of transparent superconductor /\n  two-dimensional electron gas junctions: We have measured the conductance and shot-noise of superconductor-normal\nmetal (S-N) junctions between a Niobium (Nb) film and a 2-dimensional electron\ngas (2DEG), formed in an InAs-based semiconductor heterostructure. Adjacent to\nthe junction, the 2DEG is shaped into a submicrometer beam-splitter. The\ncurrent shot-noise measured through one arm of the beam-splitter is found to be\nenhanced due to Andreev reflection. Both noise and conductance measurements\nindicate that the Nb-2DEG interface is of high quality with a transparency\napproaching approx. 60-70 %. The present device can be seen as a\nquasi-ballistic S-N beam-splitter junction."
    },
    {
        "anchor": "Dissipative dynamics of qubits driven by a bichromatic field in the\n  dispersive regime: We study the coherent dynamics of relaxing qubits driven by a bichromatic\nradiation in the dispersive regime, when detuning of the frequency\n$\\omega_{rf}$ of a longitudinal radiofrequency field from the Rabi frequency\n$\\omega_{1}$ in a transverse microwave field is comparable in magnitude to\n$\\omega_{rf}$ and $\\omega_{1}$. We analytically describe this regime beyond the\nrotating wave approximation and find that the dominant feature of dynamics of\nqubits is the shift of the Rabi frequency caused by the dynamical Zeeman and\nBloch-Siegert-like effects. These fundamental effects can be experimentally\nseparated because, unlike the Bloch-Siegert effect, the dynamical Zeeman effect\ndepends on the detuning sign. Our theoretical results are in a good agreement\nwith the experimental data obtained in pulse EPR for the $E'_{1}$ centers in\ncrystalline quartz.",
        "positive": "A semi-classical analysis of Dirac fermions in 2+1 dimensions: We investigate the semiclassical dynamics of massless Dirac fermions in 2+1\ndimensions in the presence of external electromagnetic fields. By generalizing\nthe $\\alpha$ matrices to the spin-$S$ matrices and doing a certain scaling, we\nformulate a $S\\rightarrow\\infty$ limit where the spin and the orbital degrees\nbecome classical. We solve for the classical trajectories for a free particle\non a cylinder and a particle in a constant magnetic field. We compare the\nsemiclassical spectrum, obtained by Bohr-Sommerfeld quantization with the exact\nquantum spectrum for low values of. For the free particle, the semiclassical\nspectrum is exact. For the particle in a constant magnetic field, the\nsemiclassical spectrum reproduces all the qualitative features of the exact\nquantum spectrum at all $S$. The quantitative fit for $S=1/2$ is reasonably\ngood."
    },
    {
        "anchor": "Origin of the emission within the cavity mode of coupled quantum\n  dot-cavity systems: The origin of the emission within the optical mode of a coupled quantum\ndot-micropillar system is investigated. Time-resolved photoluminescence is\nperformed on a large number of deterministically coupled devices in a wide\nrange of temperature and detuning. The emission within the cavity mode is found\nto exhibit the same dynamics as the spectrally closest quantum dot state. Our\nobservations indicate that fast dephasing of the quantum dot state is\nresponsible for the emission within the cavity mode. An explanation for recent\nphoton correlation measurements reported on similar systems is proposed.",
        "positive": "Resonant excitation of twisted spin waves in magnetic vortices using\n  rotating magnetic fields: Twisted spin waves attracted research attentions lately and the orbital\nangular momentum they carry may be utilized in communication and computing\ntechnologies. In this work, we manifest by micromagnetic simulations that\ntwisted spin wave modes naturally exist in thick ferromagnetic disks. The\ntwisted spin waves can be readily stimulated using rotating magnetic field when\nit is tuned to the eigenfrequency of corresponding modes. We analytically\nderive dispersion relation of the twisted spin waves and the results agree well\nwith the numerical studies. Lastly, we demonstrate that the topological charge\nof twisted spin waves can be controlled by the exciting field."
    },
    {
        "anchor": "Two-component nonlinear wave of the Hirota equation: Using the generalized perturbation reduction method the Hirota equation is\ntransformed to the coupled nonlinear Schr\\\"odinger equations for auxiliary\nfunctions. A solution in the form of a two-component vector nonlinear pulse is\nobtained. The components of the pulse oscillate with the sum and difference of\nthe frequencies and the wave numbers. Explicit analytical expressions for the\nshape and parameters of the two-component nonlinear pulse are presented.",
        "positive": "From electrons to baby skyrmions in Chern ferromagnets: A topological\n  mechanism for spin-polaron formation in twisted bilayer graphene: The advent of Moir\\'e materials has galvanized interest in the nature of\ncharge carriers in topological bands. In contrast to conventional materials\nwhere charge carriers are electron-like quasiparticles, topological bands allow\nfor more exotic possibilities where charge is carried by nontrivial topological\ntextures, such as skyrmions. However, the real space description of skyrmions\nis ill-suited to address the limit of small or `baby' skyrmions which consist\nof an electron and a few spin flips. Here, we study the formation of the\nsmallest skyrmions -- spin polarons, formed as bound states of an electron and\na spin flip -- in Chern ferromagnets. We show that, quite generally, there is\nan attraction between an electron and a spin flip that is purely topological in\norigin and of $p$-wave symmetry, which promotes the formation of spin polarons.\nApplying our results to the topological bands of twisted bilayer graphene, we\nidentify a range of parameters where spin polarons are formed and are lower in\nenergy than electrons. In particular, spin polarons are found to be\nenergetically cheaper on doping correlated insulators at integer fillings\ntowards charge neutrality, consistent with the absence of quantum oscillations\nand the rapid onset of flavor polarization (cascade) transition in this regime.\nOur study sets the stage for pairing of spin polarons, helping bridge skyrmion\npairing scenarios and momentum space approaches to superconductivity."
    },
    {
        "anchor": "Polarization-dependent interference between dipole moments of a\n  resonantly excited quantum dot: Resonant photoluminescence excitation (RPLE) spectra of a neutral InGaAs\nquantum dot show an unconventional line-shape that depends on the detection\npolarization. We characterize this phenomenon by performing\npolarization-dependent RPLE measurements and simulating the measured spectra\nwith a 3-level quantum model. This analysis enables us to extract the coherence\nbetween the two exciton states from the measured spectra. The good agreement\nbetween the data and model indicates that the interference between coherent\nscatterings from both fine structure split exciton states is the key to\nunderstanding this phenomenon.",
        "positive": "Rayleigh Edge Waves in Two-Dimensional Crystals with Lorentz Forces --\n  from Skyrmion Crystals to Gyroscopic Media: We investigate, within the framework of linear elasticity theory, edge\nRayleigh waves of a two-dimensional elastic solid with broken time-reversal and\nparity symmetries due to a Berry term. As our prime example, we study the\nelastic edge wave traveling along the boundary of a two-dimensional skyrmion\nlattice hosted inside a thin-film chiral magnet. We find that the direction of\npropagation of the Rayleigh modes is determined not only by the chirality of\nthe thin-film, but also by the Poisson ratio of the crystal. We discover three\nqualitatively different regions distinguished by the chirality of the\nlow-frequency edge waves, and study their properties. To illustrate the\nRayleigh edge waves in real time, we have carried out finite-difference\nsimulations of the model. Apart from skyrmion crystals, our results are also\napplicable to edge waves of gyroelastic media and screened Wigner crystals in\nmagnetic fields. Our work opens a pathway towards controlled manipulation of\nelastic signals along boundaries of crystals with broken time-reversal\nsymmetry."
    },
    {
        "anchor": "Aharonov-Bohm effect in an electron-hole graphene ring system: Aharonov-Bohm oscillations are observed in a graphene quantum ring with a top\ngate covering one arm of the ring. As graphene is a gapless semiconductor this\ngeometry allows to study not only the quantum interference of electrons with\nelectrons or holes with holes but also the unique situation of quantum\ninterference between electrons and holes. The period and amplitude of the\nobserved Aharonov-Bohm oscillations are independent of the sign of the applied\ngate voltage showing the equivalence between unipolar and dipolar interference.",
        "positive": "The 6D quantum Hall effect and 3D topological pumps: Modern technological advances allow for the study of systems with additional\nsynthetic dimensions. Using such approaches, higher-dimensional physics that\nwas previously deemed to be of purely theoretical interest has now become an\nactive field of research. In this work, we derive from first principles using a\nsemiclassical equation of motions approach, the bulk response of a\nsix-dimensional Chern insulator. We find that in such a system a quantized bulk\nresponse appears with a quantization originating from a six-dimensional\ntopological index -- the 3rd Chern number. Alongside this novel six-dimensional\nresponse, we rigorously describe the lower even-dimensional Chern-like\nresponses that can occur due to nonvanishing 1st and 2nd Chern numbers in\nsub-spaces of the six-dimensional space. Last, we propose how to realize such a\nbulk response using three-dimensional topological charge pumps in cold atomic\nsystems."
    },
    {
        "anchor": "Excitonic Tonks-Girardeau and charge-density wave phases in monolayer\n  semiconductors: Excitons in two-dimensional semiconductors provide a novel platform for\nfundamental studies of many-body interactions. In particular, dipolar\ninteractions between spatially indirect excitons may give rise to strongly\ncorrelated phases of matter that so far have been out of reach of experiments.\nHere, we show that excitonic few-body systems in atomically thin\ntransition-metal dichalcogenides undergo a crossover from a Tonks-Girardeau to\na charge-density-wave regime. To this end, we take into account realistic\nsystem parameters and predict the effective exciton-exciton interaction\npotential. We find that the pair correlation function contains key signatures\nof the many-body crossover already at small exciton numbers and show that\nphotoluminescence spectra provide readily accessible experimental fingerprints\nof these strongly correlated quantum many-body states.",
        "positive": "The Shortest Path Across the Mesoscopic System: We study distribution functions (DF) of mesoscopic hopping conductance\nnumerically by searching for the shortest path. We have found that the\ndistributions obtained by choosing randomly the chemical potentials (for a\nfixed impurity configuration), which corresponds to a typical experimental\nsituation, coincide with those obtained when both impurity configuration and\nchemical potential is chosen randomly, in agreement with the ergodicity\nhypothesis. The DFs obtained for one-dimensional systems were found to be quite\nclose to the independent predictions of V.I. Mel'nikov, A.A. Abrikosov and P.\nLee et al. For D=2, the DFs both for narrow system and thin film look similar\n(and close to the 1D case).The distribution function for the conductance of the\nsquare sample is nearly Gaussian as predicted by both Altshuler et al and\nSerota et al."
    },
    {
        "anchor": "Dielectric response and novel electromagnetic modes in three-dimensional\n  Dirac semimetal films: Using the Kubo formalism we have calculated the local dynamic conductivity of\na bulk, i.e., three-dimensional (3D), Dirac semimetal (BDS). We obtain that at\nfrequencies lower than Fermi energy the metallic response in a BDS film\nmanifests in the existence of surface-plasmon polaritons, but at higher\nfrequencies the dielectric response is dominated and it occurs that a BDS film\nbehaves as a dielectric waveguide. At this dielectric regime we predict the\nexistence inside a BDS film of novel electromagnetic modes, a 3D analog of the\ntransverse electric waves in graphene. We also find that the dielectric\nresponse manifests as the wide-angle passband in the mid-infrared (IR)\ntransmission spectrum of light incident on a BDS film, which can be used for\nthe interferenceless omnidirectional mid-IR filtering. The tuning of the Fermi\nlevel of the system allows us to switch between the metallic and the dielectric\nregimes and to change the frequency range of the predicted modes. This makes\nBDSs promising materials for photonics and plasmonics.",
        "positive": "Decoherence by Quantum Telegraph Noise: We investigate the time-evolution of a charge qubit subject to quantum\ntelegraph noise produced by a single electronic defect level. We obtain results\nfor the time-evolution of the coherence that are strikingly different from the\nusual case of a harmonic oscillator bath (Gaussian noise). When the coupling\nstrength crosses a certain temperature-dependent threshold, we observe\ncoherence oscillations in the strong-coupling regime. Moreover, we present the\ntime-evolution of the echo signal in a spin-echo experiment. Our analysis\nrelies on a numerical evaluation of the exact solution for the density matrix\nof the qubit."
    },
    {
        "anchor": "Trigonal warping and anisotropic band splitting in monolayer graphene\n  due to Rashba spin-orbit coupling: We study the electronic band structure of monolayer graphene when Rashba\nspin-orbit coupling is present. We show that if the Rashba spin-orbit coupling\nis stronger than the intrinsic spin-orbit coupling, the low energy bands\nundergo trigonal-warping deformation and that for energies smaller than the\nLifshitz energy, the Fermi circle breaks up into separate parts. The effect is\nvery similar to what happens in bilayer graphene at low energies. We discuss\nthe possible experimental implications, such as threefold increase of the\nminimal conductivity for low electron densities, the wavenumber dependence of\nthe band splitting and the spin polarization structure. Our theoretical\npredictions are in agreement with recent experimental results.",
        "positive": "Nuclear Surface Acoustic Resonance with Spin-Rotation Coupling: We show that, under an appropriate out-of-plane static magnetic field,\nnuclear spins in a thin specimen on a surface acoustic wave (SAW) cavity can be\nresonantly excited and detected through spin-rotation coupling. Since such a\nSAW cavity can have the quality factor as high as $10^{4}$ and the mode volume\nas small as $10^{-2}$ mm$^{3}$ the signal-to-noise ratio in detecting the\nresonance is estimated to be quite high. We argue that detecting nuclear spin\nresonance of a single flake of an atomically-thin layer of two-dimensional\nsemiconductor, which has so far been beyond hope with the conventional\ninductive method, can be a realistic target with the proposed scheme."
    },
    {
        "anchor": "Solvable Models of Magnetic Skyrmions: We give a succinct summary of the recently discovered solvable models of\nmagnetic skyrmions in two dimensions, and of their general solutions. The\nmodels contain the standard Heisenberg term, the most general translation\ninvariant Dzyaloshinskii-Moriya (DM) interaction term and, for each DM term, a\nparticular combination of anisotropy and Zeeman potentials. We argue that\nsimple mathematical features of the explicit solutions help understand general\nqualitative properties of magnetic skyrmion configurations in more generic\nmodels.",
        "positive": "Strain Engineering for Transition Metal Defects in SiC: Transition metal (TM) defects in silicon carbide (SiC) are a promising\nplatform for applications in quantum technology as some of these defects, e.g.\nvanadium (V), allow for optical emission in one of the telecom bands. For other\ndefects it was shown that straining the crystal can lead to beneficial effects\nregarding the emission properties. Motivated by this, we theoretically study\nthe main effects of strain on the electronic level structure and optical\nelectric-dipole transitions of the V defect in SiC. In particular we show how\nstrain can be used to engineer the g-tensor, electronic selection rules, and\nthe hyperfine interaction. Based on these insights we discuss optical Lambda\nsystems and a path forward to initializing the quantum state of strained TM\ndefects in SiC."
    },
    {
        "anchor": "Interface induced manipulation of perpendicular exchange bias in\n  Pt/Co/(Pt, Cr)/CoO thin films: Perpendicular exchange bias has been manipulated by changing ferromagnetic\nfilm thickness and spacer layer in Pt/Co/(Pt, Cr)/CoO thin films. The exchange\nbias characteristics, blocking temperature, magnetization of thin films\nstrongly depend on the spacer layer (Pt, Cr) between ferromagnetic and\nantiferromagnetic layers. While Pt/Co/Pt/CoO thin films show perpendicular\nexchange bias, Pt/Co/Cr/CoO has easy magnetization axis in the film plane. We\nhave also observed very small hysteretic behavior from the hard axis\nmagnetization curve of Pt/Co/Cr/CoO film. This can be attributed to\nmisalignment of the sample or small perpendicular contribution from Pt/Co\nbottom interface. We have also investigated the temperature and spacer layer\ndependent exchange bias properties of the samples by VSM magnetometry. We\nobserved higher HEB and HC for the thicker Co layer in the Pt/Co/Pt/CoO sample.\nIn addition, onset of exchange bias effect starts at much lower temperatures\nfor Pt/Co/Cr/CoO thin film. This clearly shows that Cr spacer layer not only\nremoves the perpendicular exchange bias, but also reduces the exchange\ninteraction between Co and CoO and thus lowers the blocking temperature.",
        "positive": "Magnetotransport signatures of three-dimensional topological insulator\n  nanostructures: We study the magnetotransport properties of patterned 3D topological\ninsulator nanostructures with several leads, such as kinks or Y-junctions, near\nthe Dirac point with analytical as well as numerical techniques. The interplay\nof the nanostructure geometry, the external magnetic field and the\nspin-momentum locking of the topological surface states lead to a richer\nmagnetoconductance phenomenology as compared to straight nanowires. Similar to\nstraight wires, a quantized conductance with perfect transmission across the\nnanostructure can be realized across a kink when the input and output channels\nare pierced by a half-integer magnetic flux quantum. Unlike for straight wires,\nthere is an additional requirement depending on the orientation of the external\nmagnetic field. A right-angle kink shows a unique $\\pi$-periodic\nmagnetoconductance signature as a function of the in-plane angle of the\nmagnetic field. For a Y-junction, the transmission can be perfectly steered to\neither of the two possible output legs by a proper alignment of the external\nmagnetic field. These magnetotransport signatures offer new ways to explore\ntopological surface states and could be relevant for quantum transport\nexperiments on nanostructures which can be realized with existing fabrication\nmethods."
    },
    {
        "anchor": "Lattice Expansion in Seamless Bi layer Graphene Constrictions at High\n  Bias: Our understanding of sp2 carbon nanostructures is still emerging and is\nimportant for the development of high performance all carbon devices. For\nexample, in terms of the structural behavior of graphene or bi-layer graphene\nat high bias, little to nothing is known. To this end we investigated bi-layer\ngraphene constrictions with closed edges (seamless) at high bias using in situ\natomic resolution transmission electron microscopy. We directly observe a\nhighly localized anomalously large lattice expansion inside the constriction.\nBoth the current density and lattice expansion increase as the bi-layer\ngraphene constriction narrows. As the constriction width decreases below 10 nm,\nshortly before failure, the current density rises to 4 \\cdot 109 A cm-2 and the\nconstriction exhibits a lattice expansion with a uniaxial component showing an\nexpansion approaching 5 % and an isotropic component showing an expansion\nexceeding 1 %. The origin of the lattice expansion is hard to fully ascribe to\nthermal expansion. Impact ionization is a process in which charge carriers\ntransfer from bonding states to antibonding states thus weakening bonds. The\naltered character of C-C bonds by impact ionization could explain the\nanomalously large lattice expansion we observe in seamless bi-layer graphene\nconstrictions. Moreover, impact ionization might also contribute to the\nobserved anisotropy in the lattice expansion, although strain is probably the\npredominant factor.",
        "positive": "Study on Transient Spectrum Based on Charge Transfer of Semiconductor\n  Quantum Dots: With the increasing energy crisis and the prevalent concept of green\nsustainability, quantum dot materials have become a hot spot in the academic\nand industrial fields of chemistry. Due to unique, tailor-made photovoltaic\nproperties based on marked quantum-confined effects, it's necessary to identify\nthe QD-based charge transfer process connected with a lifetime of stimulated\nexcitons. Additionally, inorganic nanoparticles with a continuum of electron\nstates contribute to the consistency between electron dynamics and their\nfunction through complexation with QDs. Ultrafast spectroscopy can be widely\nused in this system, the most typical of which is the time-resolved transient\nabsorption spectroscopy, especially on a femtosecond or picosecond timescale.\nIn this paper, we used the ZnSe/CdS core-shell quantum dot as the donor, and\nthe TiO2 film as the metal oxide molecule as the acceptor, through steady-state\nand transient absorption techniques. Within, the electron transfer and related\nprocesses between the two composite systems were explored, and the relationship\nbetween the electron transfer rate constant (kBET) and particle size and QD\ncore size was further studied. Through the research content of this paper, it\nis hoped to provide materials for quantum dot sensitization devices with more\ncontrollable features."
    },
    {
        "anchor": "Manipulating single photon emitter radiative lifetime in\n  transition-metal dichalcogenides through Forster resonance energy transfer to\n  graphene: Structural defects can crucially impact the optical response of monolayer\n(ML) thick materials as they enable trapping sites for excitons. These trapped\nexcitons appear in photoluminescence spectra as new emissions below the free\nbright exciton and it can be exploited for single photon emissions (SPE). In\nthis work we outline criteria, within our frame work, by which single photon\nemission can be detected in two dimensional materials and we explore how these\ncriteria can be fulfilled in atomically thin transition metal dichalcogenides\n(TMD). In particular, we model the effect of defects, in accordance with the\nmost common experimental realisations, on the spatial autocorrelation function\nof the random disorder potential. Moreover, we provide a way to control the\nradiative lifetime of these emissions by a hybride heterostructrue of the ML\nTMD with a graphene sheet and a dielectric spacer that enables the Forster\nresonance energy transfer process. Our work predict that the corresponding SPE\nquenched radiative lifetime will be in the picosecond range, this time scale is\nin good agreement with the recently measured exciton lifetime in this\nheterostructures",
        "positive": "Transduction between electrical energy and the heat in a carbon nanotube\n  using a voltage-controlled doping: High electric conductivity ~100 MegaSiemens/m and Seebeck coefficient >200\nmkV/K of carbon nanotubes (CNT) make them attractive for a variety of\napplications. Unfortunately, a high thermal conductivity ~ 3000 W/(m*K) due to\nthe phonon transport limits their capability for transforming energy between\nthe heat and electricity. Here we show that increasing the charge carrier\nconcentrations not only leads to an increase of both electric conductivity and\nSeebeck coeffcient, but also causes a substantial suppression of the thermal\nconductivity due to intensifying the phonon-electron collisions. A strong\ntransduction effect corresponding to an effective electron temperature change\n~115 K was observed in a CNT device, where the local gate electrodes have\ncontrolled the charge doping in the opposite ends. Transduction between the\nheat and the energy of the electron subsystem corresponds to an impressive\nfigure of merit cold ZT ~ 6 and the transduced power density P ~ 80kW/cm2."
    },
    {
        "anchor": "Van der Waals thin films of WTe2 for natural hyperbolic plasmonic\n  surfaces: A hyperbolic plasmonic surface supports highly directional propagating\npolaritons with extremely large density of states. Such plasmon polaritons have\nbeen realized in artificially structured metasurfaces. However, the upper bound\nof the achievable plasmon wave vector is limited by the structure size, which\ncalls for a natural hyperbolic surface without any structuring. Here, we\nexperimentally demonstrate a natural hyperbolic plasmonic surface based on thin\nfilms of WTe2 in the light wavelength range of 16 to 23 microns by far infrared\nabsorption spectroscopy. The topological transition from the elliptic to the\nhyperbolic regime is further manifested by mapping the iso-frequency contours\nof the plasmon. Moreover, the anisotropy character and plasmon frequency\nexhibit prominent temperature dependence. Our study demonstrates the first\nnatural platform to host 2D hyperbolic plasmons, which opens exotic avenues for\nthe manipulation of plasmon propagation, light-matter interaction and light\nemission in planar photonics.",
        "positive": "High Frequency Domain Wall Oscillations in Ferromagnetic Nanowire with a\n  Nanoscale Dzyaloshinskii Moriya Interaction (DMI) Region: The Dzyaloshinskii Moriya Interaction (DMI) has laid the foundation for many\nnovel chiral structures such as Skyrmions. In most of the studies so far, the\nDMI is present in the whole of the magnetic layer. Here, we report our\ninvestigations on a ferromagnetic nanowire where DMI is confined to a nanoscale\nregion. We observe that the local modulation of magnetic properties causes\noscillation of domain walls under the influence of spin-transfer torque. The\noscillation frequency is tunable within a few GHz, making this observation\npotentially useful for applications in neuromorphic computing."
    },
    {
        "anchor": "Interactions in Chaotic Nanoparticles: Fluctuations in Coulomb Blockade\n  Peak Spacings: We use random matrix models to investigate the ground state energy of\nelectrons confined to a nanoparticle. Our expression for the energy includes\nthe charging effect, the single-particle energies, and the residual screened\ninteractions treated in Hartree-Fock. This model is applicable to chaotic\nquantum dots or nanoparticles--in these systems the single-particle statistics\nfollows random matrix theory at energy scales less than the Thouless energy. We\nfind the distribution of Coulomb blockade peak spacings first for a large dot\nin which the residual interactions can be taken constant: the spacing\nfluctuations are of order the mean level separation Delta. Corrections to this\nlimit are studied using the small parameter 1/(kf L): both the residual\ninteractions and the effect of the changing confinement on the single-particle\nlevels produce fluctuations of order Delta/sqrt(kf L). The distributions we\nfind are significantly more like the experimental results than the simple\nconstant interaction model.",
        "positive": "Theory of Optical Activity in Doped Systems with Application to Twisted\n  Bilayer Graphene: We theoretically study the optical activity in a doped system and derive the\noptical activity tensor from a light wavevector-dependent linear optical\nconductivity. Although the light-matter interaction is introduced through the\nvelocity gauge from a minimal coupling Hamiltonian, we find that the well-known\n``false divergences'' problem can be avoided in practice if the electronic\nstates are described by a finite band effective Hamiltonian, such as a few-band\ntight-binding model. The expression we obtain for the optical activity tensor\nis in good numerical agreement with a recent theory derived for an undoped\ntopologically trivial gapped system. We apply our theory to the optical\nactivity of a gated twisted bilayer graphene, with a detailed discussion of the\ndependence of the results on twist angle, chemical potential, gate voltage, and\nlocation of rotation center forming the twisted bilayer graphene."
    },
    {
        "anchor": "Conductance and Its Variance of Disordered Wires with Symplectic\n  Symmetry in the Metallic Regime: The conductance of disordered wires with symplectic symmetry is studied by a\nrandom-matrix approach. It has been shown that the behavior of the conductance\nin the long-wire limit crucially depends on whether the number of conducting\nchannels is even or odd. We focus on the metallic regime where the wire length\nis much smaller than the localization length, and calculate the\nensemble-averaged conductance and its variance for both the even- and\nodd-channel cases. We find that the weak-antilocalization correction to the\nconductance in the odd-channel case is equivalent to that in the even-channel\ncase. Furthermore, we find that the variance dose not depend on whether the\nnumber of channels is even or odd. These results indicate that in contrast to\nthe long-wire limit, clear even-odd differences cannot be observed in the\nmetallic regime.",
        "positive": "Quantum Interference in Silicon 1D Quasi-Ballistic Junctionless Nanowire\n  Field Effect Transistors: We investigate the low temperature transport in 8 nm diameter Si junctionless\nnanowire field effect transistors fabricated by top down techniques with a\nwrap-around gate and two different activated doping densities. First we extract\nthe intrinsic gate capacitance of the device geometry from a device that shows\nCoulomb blockade at 13 mK with over 500 Coulomb peaks across a gate voltage\nrange of 6 V indicating the formation of a single island in the entire nanowire\nchannel. In two other devices, doped Si:P $4\\times10^{19}\\,\\text{cm}^{-3}$ and\n$2\\times10^{20}\\,\\text{cm}^{-3}$, we observe quantum interference and use the\nextracted gate coupling to determine the dominant energy scale and the\ncorresponding mean-free paths. For the higher doped device the analysis yields\na mean free path of $4\\pm2\\,\\text{nm}$, which is on the order of the average\ndopant spacing and suggests scattering on unactivated or activated dopants. For\nthe device with an activated dopant density of $4\\times10^{19}\\,\\text{cm}^{-3}$\nthe quantum interference effects suggest a mean free path of\n$10\\pm2\\,\\text{nm}$, which is comparable to the nanowire width, and thus\nquasi-ballistic transport. A temperature dependent analysis of Universal\nConductance Fluctuations suggests a coherence length above the nanowire length\nfor temperatures below 1.9 K and decoherence from 1D electron-electron\ninteractions for higher temperatures. The mobility is limited by scattering on\nimpurities rather than the expected surface roughness scattering for nanowires\nwith diameters larger or comparable to the Fermi wavelength. Our measurements\ntherefore provide insight into the performance limitations from dominant\nscattering and dephasing mechanisms in technologically relevant silicon device\ngeometries."
    },
    {
        "anchor": "Flip-chip-based microwave spectroscopy of Andreev bound states in a\n  planar Josephson junction: We demonstrate a flip-chip-based approach to microwave measurements of\nAndreev bound states in a gate-tunable planar Josephson junction using\ninductively-coupled superconducting low-loss resonators. By means of\nelectrostatic gating, we present control of both the density and transmission\nof Andreev bound states. Phase biasing of the device shifted the resonator\nfrequency, consistent with the modulation of supercurrent in the junction.\nTwo-tone spectroscopy measurements revealed an isolated Andreev bound state\nconsistent with an average induced superconducting gap of $184~\\mathrm{\\mu eV}$\nand a gate-tunable transmission approaching $0.98$. Our results represent the\nfeasibility of using the flip-chip technique to address and study Andreev bound\nstates in planar Josephson junctions, and they give a promising path towards\nmicrowave applications with superconductor-semiconductor two-dimensional\nmaterials.",
        "positive": "Large Proximity-Induced Spin Lifetime Anisotropy in Transition Metal\n  Dichalcogenide/Graphene Heterostructures: Van-der-Waals heterostructures have become a paradigm for designing new\nmaterials and devices, in which specific functionalities can be tailored by\ncombining the properties of the individual 2D layers. A single layer of\ntransition metal dichalcogenide (TMD) is an excellent complement to graphene\n(Gr), since the high quality of charge and spin transport in Gr is enriched\nwith the large spin-orbit coupling of the TMD via proximity effect. The\ncontrollable spin-valley coupling makes these heterostructures particularly\nattractive for spintronic and opto-valleytronic applications. In this work, we\nstudy spin precession in a monolayer MoSe2/Gr heterostructure and observe an\nunconventional, dramatic modulation of the spin signal, showing one order of\nmagnitude longer lifetime of out-of-plane spins (40 ps) compared with that of\nin-plane spins (3.5 ps). This demonstration of a large spin lifetime anisotropy\nin TMD/Gr heterostructures, is a direct evidence of induced spin-valley\ncoupling in Gr and provides an accessible route for manipulation of spin\ndynamics in Gr, interfaced with TMDs."
    },
    {
        "anchor": "Impurity states of electrons on the surface of a nanotube in a magnetic\n  field: The localization of electrons in the field of isolated nonmagnetic impurity\natoms on the surface of a nanotube in a magnetic field is considered. A model\nof a Gaussian separable impurity potential capable of localizing an electron at\nany intensity is used. The positions of the local level are found in the regime\nof strong and weak localizations. The positions of the resonances are found,\ntheir widths are estimated. They experience Aharonov-Bohm oscillations when the\nmagnetic flux in the tube changes. It is shown that the positions of the\nresonances experience oscillations similar to the de Haas-van Alphen\noscillations, which are not associated with a magnetic field.",
        "positive": "First-principles study of carbon impurities in\n  CuIn$_{1-x}$Ga$_x$Se$_{2}$, present in nonvacuum synthesis methods: A first-principles study of the structural and electronic properies of carbon\nimpurities in CuIn$_{1-x}$Ga$_x$Se$_{2}$ is presented. Carbon is present in\norganic molecules in the precursor solutions used in nonvacuum growth methods,\nmaking more efficient use of material, time and energy than traditional vacuum\nmethods. The formation energies of several carbon impurities are calculated\nusing the hybrid HSE06 functional. C$_{\\mathrm{Cu}}$ acts as a shallow donor,\nC$_{\\mathrm{In}}$ and interstitial C yield deep donor levels in CuInSe$_{2}$,\nwhile in CuGaSe$_{2}$ C$_{\\mathrm{Ga}}$ and interstitial C act as deep\namphoteric defects. So, if present, these defects reduce the majority carrier\n(hole) concentration by compensating the acceptor levels and become trap states\nfor the photogenerated minority carriers (electrons). However, the formation\nenergies of the calculated carbon impurities are high, even under C-rich growth\nconditions. Therefore, these impurities are not likely to form and will\nprobably be expelled to the intergranular region and out of the absorber layer."
    },
    {
        "anchor": "Cryogenic in-memory computing using tunable chiral edge states: Energy-efficient hardware implementation of machine learning algorithms for\nquantum computation requires nonvolatile and electrically-programmable devices,\nmemristors, working at cryogenic temperatures that enable in-memory computing.\nMagnetic topological insulators are promising candidates due to their tunable\nmagnetic order by electrical currents with high energy efficiency. Here, we\nutilize magnetic topological insulators as memristors (termed magnetic\ntopological memristors) and introduce a chiral edge state-based cryogenic\nin-memory computing scheme. On the one hand, the chiral edge state can be tuned\nfrom left-handed to right-handed chirality through spin-momentum locked\ntopological surface current injection. On the other hand, the chiral edge state\nexhibits giant and bipolar anomalous Hall resistance, which facilitates the\nelectrical readout. The memristive switching and reading of the chiral edge\nstate exhibit high energy efficiency, high stability, and low stochasticity. We\nachieve high accuracy in a proof-of-concept classification task using four\nmagnetic topological memristors. Furthermore, our algorithm-level and\ncircuit-level simulations of large-scale neural networks based on magnetic\ntopological memristors demonstrate a software-level accuracy and lower energy\nconsumption for image recognition and quantum state preparation compared with\nexisting memristor technologies. Our results may inspire further topological\nquantum physics-based novel computing schemes.",
        "positive": "Full-scale Simulation of Electron Transport in Nanoporous Graphene:\n  Probing the Talbot Effect: Designing platforms to control phase-coherence and interference of electron\nwaves is a cornerstone for future quantum electronics, computing or sensing.\nNanoporous graphene (NPG) consisting of linked graphene nanoribbons has\nrecently been fabricated using molecular precursors and bottom-up assembly\n[Moreno et al., Science 360, 199 (2018)] opening an avenue for controlling the\nelectronic current in a two-dimensional material. By simulating electron\ntransport in real-sized NPG samples we predict that electron waves injected\nfrom the tip of a scanning tunneling microscope (STM) behave similarly to\nphotons in coupled waveguides, displaying a Talbot interference pattern. We\nlink the origins of this effect to the band structure of the NPG and further\ndemonstrate how this pattern may be mapped out by a second STM probe. We enable\natomistic parameter-free calculations beyond the 100 nm scale by developing a\nnew multi-scale method where first-principles density functional theory regions\nare seamlessly embedded into a large-scale tight-binding."
    },
    {
        "anchor": "Exchange gap in GdPtBi probed by magneto-optics: We measured the magneto-reflectivity spectra (4 - 90 meV, 0 - 16 T) of the\ntriple-point semimetal GdPtBi and found them to demonstrate two unusual broad\nfeatures emerging in field. The electronic bands of GdPtBi are expected to\nexperience large exchange-mediated shifts, which lends itself to a description\nvia effective Zeeman splittings with a large g factor. Based on this approach,\nalong with an ab initio band structure analysis, we propose a model Hamiltonian\nthat describes our observations well and allows us to estimate the effective g\nfactor, g* = 95. We conclude that we directly observe the exchange-induced\n$\\Gamma_{8}$ band inversion in GdPtBi by means of infrared spectroscopy.",
        "positive": "Enhanced gyration-signal propagation speed in one-dimensional\n  vortex-antivortex lattices and its control by perpendicular bias field: We report on a micromagnetic simulation study of coupled core gyrations in\none-dimensional (1D) alternating vortex-antivortex (V-AV) lattices formed in\nconnected soft-magnetic-disk arrays (round-shaped modulated nanostrips). In the\nV-AV lattices, we found very characteristic standing-wave modes of the coupled\ngyrations as well as efficiently ultrafast gyration-signal propagation between\nvortices through the neighboring antivortices, as originating from their\ncombined strong exchange and dipole interactions. Collective core oscillations\nin the V-AV networks are characterized as unique two-branch magnonic bands that\nare affected by the polarization ordering between the neighboring vortex and\nantivortex and controllable by externally applied perpendicular fields each of\ndifferent field strength and direction. The gyration-signal propagation speed\nis much faster than that for 1D disk arrays composed only of vortex states, and\nthe propagation speed for the parallel polarization ordering is increased,\nremarkably, to more than 1 km/sec by application of perpendicular static\nfields. This work provides a fundamental understanding of the coupled dynamics\nof topological solitons as well as an additional mechanism for ultrafast\ngyration-signal propagation; moreover, it offers an efficient means of\nsignificant propagation-speed enhancement that is suitable for information\ncarrier applications in continuous nanostrips."
    },
    {
        "anchor": "Electrostatically confined monolayer graphene quantum dots with orbital\n  and valley splittings: The electrostatic confinement of massless charge carriers is hampered by\nKlein tunneling. Circumventing this problem in graphene mainly relies on\ncarving out nanostructures or applying electric displacement fields to open a\nband gap in bilayer graphene. So far, these approaches suffer from edge\ndisorder or insufficiently controlled localization of electrons. Here we\nrealize an alternative strategy in monolayer graphene, by combining a\nhomogeneous magnetic field and electrostatic confinement. Using the tip of a\nscanning tunneling microscope, we induce a confining potential in the Landau\ngaps of bulk graphene without the need for physical edges. Gating the localized\nstates towards the Fermi energy leads to regular charging sequences with more\nthan 40 Coulomb peaks exhibiting typical addition energies of 7-20 meV. Orbital\nsplittings of 4-10 meV and a valley splitting of about 3 meV for the first\norbital state can be deduced. These experimental observations are\nquantitatively reproduced by tight binding calculations, which include the\ninteractions of the graphene with the aligned hexagonal boron nitride\nsubstrate. The demonstrated confinement approach appears suitable to create\nquantum dots with well-defined wave function properties beyond the reach of\ntraditional techniques.",
        "positive": "Electric-field-induced Z2 topological phase transition in strained\n  single bilayer Bi(111): For controlling the critical electric fields of the topological phase\ntransition in single bilayer Bi(111), we investigated topological phases in a\nstrained system through first-principles calculations. We found a quadratic\nband touching semimetallic state at tensile strain $\\epsilon=0.5$%. Around this\nstrain, the topological phase can be switched to a trivial insulator by an\ninfinitesimal electric field. The positions at which Dirac cones appear in the\nelectric-field-induced topological phase transition changed for the strain\n$\\epsilon>0.5$% and $\\epsilon<0.5$%. Our results indicate that this topological\nphase transition could be applied to novel spintronic devices."
    },
    {
        "anchor": "Injection of a single electron from static to moving quantum dots: We study the injection mechanism of a single electron from a static quantum\ndot into a moving quantum dot created in a long depleted channel with surface\nacoustic waves (SAWs). We demonstrate that such a process is characterized by\nan activation law with a threshold that depends on the SAW amplitude and the\ndot-channel potential gradient. By increasing sufficiently the SAW modulation\namplitude, we can reach a regime where the transfer is unitary and potentially\nadiabatic. This study points at the relevant regime to use moving dots in\nquantum information protocols.",
        "positive": "Electro-magnetic Aharonov-Bohm effect in a 2-D electron gas ring: We define a mesoscopic ring in a 2-dimensional electron gas (2DEG)\ninterrupted by two tunnel barriers, enabling us to apply a well-defined\npotential difference between the two halves of the ring. The electron\ninterference in the ring is modified using a perpendicular magnetic field and a\nbias voltage. We observe clear Aharonov-Bohm oscillations up to the quantum\nHall regime as a function of both parameters. The electron travel time between\nthe barriers is found to increase with the applied magnetic field. Introducing\na scattering model, we develop a new method to measure the non-equilibrium\nelectron dephasing time, which becomes very short at high voltages and magnetic\nfields. The relevance of electron-electron interactions is discussed."
    },
    {
        "anchor": "A Reconfigurable Gate Architecture for Si/SiGe Quantum Dots: We demonstrate a reconfigurable quantum dot gate architecture that\nincorporates two interchangeable transport channels. One channel is used to\nform quantum dots and the other is used for charge sensing. The quantum dot\ntransport channel can support either a single or a double quantum dot. We\ndemonstrate few-electron occupation in a single quantum dot and extract\ncharging energies as large as 6.6 meV. Magnetospectroscopy is used to measure\nvalley splittings in the range of 35-70 microeV. By energizing two additional\ngates we form a few-electron double quantum dot and demonstrate tunable tunnel\ncoupling at the (1,0) to (0,1) interdot charge transition.",
        "positive": "Collective spontaneous emission from a system of quantum dots: We study the spontaneous emission from a regular lateral array or a randomly\ndistributed ensemble of quantum dots under strong excitation (full inversion)\nconditions. We focus on the similarities and differences between the cases of\nrandom and regular arrangement of the dots and show that there is very little\ndifference between the evolution of luminescence in these two cases, both for\nidentical dots and for a realistically inhomogeneously broadened ensemble. This\nmeans that the enhanced emission or superradiance effect is not due to\naccidental clustering of pairs of dots. Moreover, we point out that observation\nof an enhanced emission under weak excitation does not prove that true\nsuperradiance will develop in a fully inverted system."
    },
    {
        "anchor": "Local Geometric Phase and Quantum State Tomography in a Superconducting\n  Qubit: We investigate quantum state reconstruction of a superconducting qubit\nthreaded by an Aharonov-Bohm flux, with particular attention to the local\ngeometric phase. A state reconstruction scheme is introduced with a proper\naccount of the local geometric phase generated by Faraday's law of induction.\nOur scheme is based on measurement of three complementary quantities, that is,\nthe extra charge and two local currents. Incorporating time-reversal symmetry\nand the Faraday's law, we show that the full density matrix can be\nreconstructed without ambiguity in the choice of gauge. This procedure clearly\ndemonstrates that the quantum Faraday effect plays an essential role in the\ndynamics of a quantum system that involves Aharonov-Bohm flux.",
        "positive": "Heat transfer statistics in extreme-near-field radiation: We investigate the full counting statistics of extreme-near-field radiative\nheat transfer using nonequilibrium Green's function formalism. In the extreme\nnear field, the electron-electron interactions between two metallic bodies\ndominate the heat transfer process. We start from a general tight-binding\nelectron Hamiltonian and obtain a Levitov-Lesovik like scaled cumulant\ngenerating function (SCGF) using random phase approximation to deal with\nelectron-electron interaction. The expressions of heat current and its\nfluctuation (second cumulant) are obtained from the SCGF. The fluctuation\nsymmetry relation of the SCGF is verified. In the linear response limit (small\ntemperature gradient), we express the heat current cumulant by a linear\ncombination of lower order cumulants. The heat current fluctuation is $2k_B\nT^2$ times the thermal conductance with $T$ the average temperature in the\nlinear response limit, and this provides an evaluation of heat current\nfluctuation by measuring the thermal conductance in extreme-near\nfield-radiative heat transfer."
    },
    {
        "anchor": "Quantum Logic Processor: A Mach Zehnder Interferometer based Approach: Quantum Logic Processors can be implemented with Mach Zehnder\nInterferometer(MZI) configurations for the Quantum logic operations and gates.\nIn this paper, its implementation for both optical and electronic system has\nbeen presented. The correspondence between Jones matrices for photon\npolarizations and Pauli spin matrices for electrons gives a representation of\nall the unitary matrices for the quantum gate operations. A novel quantum\ncomputation system based on a Electronic Mach Zehnder Interferometer(MZI) has\nalso been proposed. It uses the electron spin as the primary qubit. Rashba\neffect is used to create Unitary transforms on spin qubits. A mesoscopic Stern\nGerlach apparatus can be used for both spin injection and detection. An\nintertwined nanowire design is used for the MZI. The system can implement all\nsingle and double qubit gates. It can easily be coupled to form an array. Thus\nthe Quantum Logic Processor (QLP) can be built using the system as its\nprototype.",
        "positive": "Fluxonium: single Cooper pair circuit free of charge offsets: The promise of single Cooper pair quantum circuits based on tunnel junctions\nfor metrology and quantum information applications is severely limited by the\ninfluence of \"offset\" charges - random, slowly drifting microscopic charges\ninherent to many solid-state systems. By shunting a small junction with the\nJosephson kinetic inductance of a series array of large capacitance tunnel\njunctions, thereby ensuring that all superconducting islands are connected to\nthe circuit by at least one large junction, we have realized a new\nsuperconducting artificial atom which is totally insensitive to offset charges.\nYet, its energy levels manifest the anharmonic structure associated with single\nCooper pair effects, a useful component for solid state quantum computation."
    },
    {
        "anchor": "Quantized Hall conductance in graphene by nonperturbative\n  magnetic-field-containing relativistic tight-binding approximation method: In this study, we conducted a numerical investigation on the Hall conductance\n($\\sigma_{Hall}$) of graphene based on the magnetic energy band structure\ncalculated using a nonperturbative magnetic-field-containing relativistic\ntight-binding approximation (MFRTB) method. The nonperturbative MFRTB can\nrevisit two types of plateaus for the dependence of $\\sigma_{Hall}$ on Fermi\nenergy. One set is characterized as wide plateaus (WPs). These WPs have filling\nfactors (FFs) of 2, 6, 10, 14, etc. and are known as the half-integer quantum\nHall effect. The width of WPs decreases with increasing FF, which exceeds the\ndecrease expected from the linear dispersion relation of graphene. The other\nset is characterized by narrow plateaus (NPs), which have FFs of 0, 4, 8, 12,\netc. The NPs correspond to the energy gaps caused by the spin-Zeeman effect and\nspin-orbit interaction. Furthermore, it was discovered that the degeneracy of\nthe magnetic energy bands calculated using the nonperturbative MFRTB method\nleads to a quantized $\\sigma_{Hall}$.",
        "positive": "Enhancing the spin transfer torque in magnetic tunnel junctions by ac\n  modulation: The phenomenon of spin transfer torque (STT) has attracted a great deal of\ninterests due to its promising prospects in practical spintronic devices. In\nthis paper, we report a theoretical investigation of STT in a noncollinear\nmagnetic tunnel junction under ac modulation based on the nonequilibrium\nGreen's function formalism, and derive a closed-formulation for predicting the\ntime-averaged STT. Using this formulation, the ac STT of a\ncarbon-nanotube-based magnetic tunnel junction is analyzed. Under ac\nmodulation, the low-bias linear (quadratic) dependence of the in-plane\n(out-of-plane) torque on bias still holds, and the $\\sin\\theta$ dependence on\nthe noncollinear angle is maintained. By photon-assisted tunneling, the\nbias-induced components of the in-plane and out-of-plane torques can be\nenhanced significantly, about 12 and 75 times, respectively. Our analysis\nreveals the condition for achieving optimized STT enhancement and suggests that\nac modulation is a very effective way for electrical manipulation of STT."
    },
    {
        "anchor": "Efficient atomic self-interaction correction scheme for non-equilibrium\n  quantum transport: Density functional theory calculations of electronic transport based on local\nexchange and correlation functionals contain self-interaction errors. These\noriginate from the interaction of an electron with the potential generated by\nitself and may be significant in metal-molecule-metal junctions due to the\nlocalized nature of the molecular orbitals. As a consequence, insulating\nmolecules in weak contact with metallic electrodes erroneously form highly\nconducting junctions, a failure similar to the inability of local functionals\nof describing Mott-Hubbard insulators. Here we present a fully self-consistent\nand still computationally undemanding self-interaction correction scheme that\novercomes these limitations. The method is implemented in the Green's function\nnon-equilibrium transport code Smeagol and applied to the prototypical cases of\nbenzene molecules sandwiched between gold electrodes. The self-interaction\ncorrected Kohn-Sham highest occupied molecular orbital now reproduces closely\nthe negative of the molecular ionization potential and is moved away from the\ngold Fermi energy. This leads to a drastic reduction of the low bias current in\nmuch better agreement with experiments.",
        "positive": "Theory of quasi-ballistic FET: steady-state regime and low-frequency\n  noise: We present the theoretical analysis of steady state regimes and low-frequency\nnoises in quasi-ballistic FETs. The noise analysis is based on the Langevin\napproach, which accounts for the microscopic sources of fluctuations originated\nfrom intrachannel electron scattering. The general formulas for local\nfluctuations of the carrier concentration, velocity and electrostatic potential\nas well, as their distributions along the channel are found as functions of\napplied voltage/current. Two circuit regimes with stabilized current and\nstabilized voltage are considered. The noise intensities for the devices with\ndifferent ballisticity are compared. We suggest that the presented analysis\nmakes better comprehension of physics of electron transport and fluctuations in\nquasi-ballistic FETs, improves their theoretical description and can be useful\nfor device simulation and design."
    },
    {
        "anchor": "The fate of half-metallicity near interfaces: the case of NiMnSb/MgO and\n  NiMnSi/MgO: The electronic and magnetic properties of the interfaces between the\nhalf-metallic Heusler alloys NiMnSb, NiMnSi and MgO have been investigated\nusing first-principles density-functional calculations with projector augmented\nwave potentials generated in the generalized gradient approximation. In the\ncase of the NiMnSb/MgO (100) interface the half-metallicity is lost, whereas\nthe MnSb/MgO contact in the NiMnSb/MgO (100) interface maintains a substantial\ndegree of spin polarization at the Fermi level ($\\sim 60$%). Remarkably, the\nNiMnSi/MgO (111) interface shows 100% spin polarization at the Fermi level,\ndespite considerable distortions at the interface, as well as rather short Si/O\nbonds after full structural optimization. This behavior markedly distinguishes\nNiMnSi/MgO (111) from the corresponding NiMnSb/CdS and NiMnSb/InP interfaces.",
        "positive": "Conductance of a Semiconductor-Superconductor junction in high magnetic\n  field: Conductance $G$ of a 2DEG-Superconductor (S) device in a high magnetic field\nis studied: $G(\\nu)$ is calculated. When the cyclotron diameter in 2DEG is\nlarger than the width of the 2DEG-S surface then $G(\\nu)$ becomes nonmonotonous\nfunction due to the Aharonov--Bohm type interference of quasiparticles at the\nsurface. At certain parameters of the junction the conductance oscillates with\n$\\nu$."
    },
    {
        "anchor": "Fano resonances in optical spectra of semiconductor quantum wells driven\n  by an oscillating field: Optical spectra of semiconductor quantum wells driven by an off-resonant\noscillating field are studied theoretically. Due to the dynamical stabilization\neffect, the field induces the quasi-stationary electron states confined at\nrepulsive scatterers and immersed into the continuum of states of conduction\nelectrons. As a result, the Fano resonances in the spectra of interband optical\ntransitions appear near the energies of the quasi-stationary states.",
        "positive": "Electron correlation in the second Landau level; a competition between\n  many, nearly degenerate quantum phases: At a very low temperature of 9mK, electrons in the 2nd Landau level of an\nextremely high mobility two-dimensional electron system exhibit a very complex\nelectronic behavior. With varying filling factor, quantum liquids of different\norigins compete with several insulating phases leading to an irregular pattern\nin the transport parameters. We observe a fully developed $\\nu=2+2/5$ state\nseparated from the even-denominator $\\nu=2+1/2$ state by an insulating phase\nand a $\\nu=2+2/7$ and $\\nu=2+1/5$ state surrounded by such phases. A developing\nplateau at $\\nu=2+3/8$ points to the existence of other even-denominator\nstates."
    },
    {
        "anchor": "Radio frequency performance projection and stability trade-off of h-BN\n  encapsulated graphene field-effect transistors: Hexagonal boron nitride (h-BN) encapsulation significantly improves carrier\ntransport in graphene. This work investigates the benefit of implementing the\nencapsulation technique in graphene field-effect transistors (GFET) in terms of\ntheir radio frequency (RF) performance. For such a purpose, a drift-diffusion\nself-consistent simulator is prepared to get the GFET electrical\ncharacteristics. Both the mobility and saturation velocity information are\nobtained by means of an ensemble Monte Carlo simulator upon considering the\nrelevant scattering mechanisms that affect carrier transport. RF figures of\nmerit are simulated using an accurate small-signal model that includes\nnon-reciprocal capacitances. Results reveal that the cutoff frequency could\nscale up to the physical limit given by the inverse of the transit time.\nProjected maximum oscillation frequencies, in the order of few THz, are\nexpected to exceed the values demonstrated by InP and Si based RF transistors.\nThe existing trade-off between power gain and stability and the role played by\nthe gate resistance are also studied. High power gain and stability are\nfeasible even if the device is operated far away from current saturation.\nFinally, the benefits of device unilateralization and the exploitation of the\nnegative differential resistance region to get negative-resistance gain are\ndiscussed.",
        "positive": "NMR Tracing of Hyperfine-Mediated Nuclear Spin Diffusion in Fractional\n  Quantum Hall Domain Phases: We present an enhanced diffusion of nuclear spin polarization in fractional\nquantum Hall domain phases at $\\nu = 2/3$. Resistively-detected NMR mediated by\nelectrically driven domain-wall motion is used as a probe of local nuclear\npolarization, manifesting pumping-dependent signal saturation behavior. This\nreveals that a relatively homogeneous polarization profile spreads even to\nplaces distant from pinning centers of the domain walls. We attribute this to\nthe fact that the pumped nuclear polarization near the domain walls rapidly\ndiffuses into the domains where nuclei experience Knight fields on comparable\nlevels. The anomalous enhancement of nuclear diffusion may be interpreted in\nterms of indirect hyperfine-mediated interaction between nuclear spins in the\ndomains."
    },
    {
        "anchor": "Relation between Johnson Noise and heating power in a two-terminal\n  conductor: We consider the Johnson noise of a two-dimensional, two-terminal electrical\nconductor for which the electron system obeys the Wiedemann-Franz law. We\nderive two simple and generic relations between the Johnson Noise temperature\nand the heat flux into the electron system. First, we consider the case where\nthe electron system is heated by Joule heating from a DC current, and we show\nthat there is a universal proportionality coefficient between the Joule power\nand the increase in Johnson noise temperature. Second, we consider the case\nwhere heat flows into the sample from an external source, and we derive a\nsimple relation between the Johnson noise temperature and the heat flux across\nthe boundary of the sample.",
        "positive": "Spin currents in a coherent exciton gas: Spin currents and spin textures are observed in a coherent gas of indirect\nexcitons. Applied magnetic fields bend the spin current trajectories and\ntransform patterns of linear polarization from helical to spiral and patterns\nof circular polarization from four-leaf to bell-like-with-inversion."
    },
    {
        "anchor": "Gauging a quantum heat bath with dissipative Landau-Zener transitions: We calculate the exact Landau-Zener transitions probabilities for a qubit\nwith arbitrary linear coupling to a bath at zero temperature. The final quantum\nstate exhibits a peculiar entanglement between the qubit and the bath. In the\nspecial case of a diagonal coupling, the bath does not influence the transition\nprobability, whatever the speed of the Landau-Zener sweep. It is proposed to\nuse Landau-Zener transitions to determine both the reorganization energy and\nthe integrated spectral density of the bath. Possible applications include\ncircuit QED and molecular nanomagnets.",
        "positive": "Induced spin-orbit coupling in silicon thin films by bismuth doping: We demonstrate an enhancement of the spin-orbit coupling in silicon (Si) thin\nfilms by doping with bismuth (Bi), a heavy metal, using ion implantation.\nQuantum corrections to conductance at low temperature in phosphorous-doped Si\nbefore and after Bi implantation is measured to probe the increase of the\nspin-orbit coupling, and a clear modification of magnetoconductance signals is\nobserved: Bi doping changes magnetoconductance from weak localization to the\ncrossover between weak localization and weak antilocalization. The elastic\ndiffusion length, phase coherence length and spin-orbit coupling length in Si\nwith and without Bi implantation are estimated, and the spin-orbit coupling\nlength after the Bi doping becomes the same order of magnitude (Lso = 54 nm)\nwith the phase coherence length (L{\\phi} = 35 nm) at 2 K. This is an\nexperimental proof that the spin-orbit coupling strength in Si thin film is\ntunable by doping with heavy metals."
    },
    {
        "anchor": "The problem of phase breaking in the electronic conduction in mesoscopic\n  systems: a linear-response theory approach: We study the problem of electronic conduction in mesoscopic systems when the\nelectrons are allowed to interact not only with static impurities, but also\nwith a scatterer (a phase breaker(PB)) that possesses internal degrees of\nfreedom. We first analyze the role of the PB in reducing the coherent\ninterference effects in a one-electron quantum-mechanical system. In the\nmany-electron system we can make a number of quite general statements within\nthe framework of linear-response theory and the random-phase approximation. We\ncannot calculate the conductivity tensor in full generality: we thus resort to\na model, in which that tensor can be expressed entirely in a single-electron\npicture. The resulting zero-temperature conductance can be written in terms of\nthe total transmission coefficient at the Fermi energy, containing an\nadditional trace over the states of the PB.",
        "positive": "Read-out of Quasi-periodic Systems using Qubits: We develop a theoretical scheme to perform a read-out of the properties of a\nquasi-periodic system by coupling it to one or two qubits. We show that the\ndecoherence dynamics of a single qubit coupled via a pure dephasing type term\nto a 1D quasi-periodic system with a potential given by the\nAndr\\'e-Aubry-Harper (AAH) model and its generalized versions (GAAH model) is\nsensitive to the nature of the single particle eigenstates (SPEs). More\nspecifically, we can use the non-markovianity of the qubit dynamics as\nquantified by the backflow of information to clearly distinguish the localized,\ndelocalized, and mixed regimes with a mobility edge of the AAH and GAAH model\nand evidence the transition between them. By attaching two qubits at distinct\nsites of the system, we demonstrate that the transport property of the\nquasi-periodic system is encoded in the scaling of the threshold time to\ndevelop correlations between the qubits with the distance between the qubits.\nThis scaling can also be used to distinguish and infer different regimes of\ntransport such as ballistic, diffusive and no transport engendered by SPEs that\nare delocalized, critical and localized respectively. When there is a mobility\nedge allowing the coexistence of different kinds of SPEs in the spectrum, such\nas the coexistence of localized and delocalized states in the GAAH models, we\nfind that the transport behaviour and the scaling of the threshold time with\nqubit separation is governed by the fastest spreading states."
    },
    {
        "anchor": "Moir\u00e9 magnets: We introduce a general framework to study moir\\'e structures of\ntwo-dimensional Van der Waals magnets using continuum field theory. The\nformalism eliminates quasiperiodicity and allows a full understanding of\nmagnetic structures and their excitations. In particular, we analyze in detail\ntwisted bilayers of N\\'eel antiferromagnets on the honeycomb lattice. A rich\nphase diagram with non-collinear twisted phases is obtained, and spin waves are\nfurther calculated. Direct extensions to zig-zag antiferromagnets and\nferromagnets are also presented. We anticipate the results and formalism\npresented to lead to a broad range of applications to both fundamental research\nand experiments.",
        "positive": "Formation of quantum spin Hall state on Si surface and energy gap\n  scaling with strength of spin orbit coupling: For potential applications in spintronics and quantum computing, it is\ndesirable to place a quantum spin Hall insulator [i.e., a 2D topological\ninsulator (TI)] on a substrate while maintaining a large energy gap. Here, we\ndemonstrate a unique approach to create the large-gap 2D TI state on a\nsemiconductor surface, based on first-principles calculations and effective\nHamiltonian analysis. We show that when heavy elements with strong spin orbit\ncoupling (SOC) such as Bi and Pb atoms are deposited on a patterned H-Si(111)\nsurface into a hexagonal lattice, they exhibit a 2D TI state with a large\nenergy gap of over 0.5 eV. The TI state arises from an intriguing substrate\norbital filtering effect that selects a suitable orbital composition around the\nFermi level, so that the system can be matched onto a four-band effective model\nHamiltonian. Furthermore, it is found that within this model, the SOC gap does\nnot increase monotonically with the increasing strength of SOC. These\ninteresting results may shed new light in future design and fabrication of\nlarge-gap topological quantum states."
    },
    {
        "anchor": "Effect of uniaxial strain on the optical Drude scattering in graphene: Graphene is a mechanically robust 2D material promising for flexible\noptoelectronic applications. However, its electromagnetic properties under\nstrain are experimentally poorly understood. Here we present the far-infrared\ntransmission spectra of large-area chemical-vapor deposited monolayer graphene\non a polyethylene terephthalate substrate subjected to uniaxial strain. The\neffective strain value is calibrated using the Raman spectroscopy and corrected\nfor a relaxation of wrinkles and folds seen directly by atomic-force\nmicroscopy. We find that while the Drude weight and the Fermi level remain\nconstant, the scattering rate increases by more than 10% per 1% of applied\nstrain, showing a high level of reproducibility during strain cycling. As a\nresult, the electronic mobility and optical absorption of graphene at terahertz\nand lower frequencies appear to also be sensitive to strain, which opens\npathways to control these key parameters mechanically. We suggest that such a\nfunctionality can be potentially used in flexible optoelectronic and\nmicroelectromechanical systems based on graphene. By combining our findings\nwith existing theoretical models, we discuss the possible mechanisms of\nstrain-controlled Drude scattering.",
        "positive": "Magnetic anisotropy of critical current in nanowire Josephson junction\n  with spin-orbit interaction: We develop and study theoretically a minimal model of semiconductor nanowire\nJosephson junction that incorporates Zeeman and spin-orbit effects. The DC\nJosephson current is evaluated from the phase-dependent energies of Andreev\nlevels. Upon changing the magnetic field applied, the critical current\noscillates manifesting cusps that signal the $0$-$\\pi$ transition. Without\nspin-orbit interaction, the oscillations and positions of cusps are regular and\ndo not depend on the direction of magnetic field. In the presence of spin-orbit\ninteraction, the magnetic field dependence of the current becomes anisotropic\nand irregular. We investigate this dependence in detail and show that it may be\nused to characterize the strength and direction of spin-orbit interaction in\nexperiments with nanowires."
    },
    {
        "anchor": "Enhanced topological superconductivity in spatially modulated planar\n  Josephson junctions: We propose a semiconductor-superconductor hybrid device for realizing\ntopological superconductivity and Majorana zero modes consisting of a planar\nJosephson junction structure with periodically modulated junction width. By\nperforming a numerical analysis of the effective model describing the\nlow-energy physics of the hybrid structure, we demonstrate that the modulation\nof the junction width results in a substantial enhancement of the topological\ngap and, consequently, of the robustness of the topological superconducting\nphase and associated Majorana zero modes. This enhancement is due to the\nformation of minibands with strongly renormalized effective parameters,\nincluding stronger spin-orbit coupling, generated by the effective periodic\npotential induced by the modulated structure. In addition to a larger\ntopological gap, the proposed device supports a topological superconducting\nphase that covers a significant fraction of the parameter space, including the\nlow Zeeman field regime, in the absence of a superconducting phase difference\nacross the junction. Furthermore, the optimal regime for operating the device\ncan be conveniently accessed by tuning the potential in the junction region\nusing, for example, a top gate.",
        "positive": "Universal Magnetic Properties of sp$^3$-type Defects in Covalently\n  Functionalized Graphene: Using density-functional calculations, we study the effect of sp$^3$-type\ndefects created by different covalent functionalizations on the electronic and\nmagnetic properties of graphene. We find that the induced magnetic properties\nare {\\it universal}, in the sense that they are largely independent on the\nparticular adsorbates considered. When a weakly-polar single covalent bond is\nestablished with the layer, a local spin-moment of 1.0 $\\mu_B$ always appears\nin graphene. This effect is similar to that of H adsorption, which saturates\none $p_z$ orbital in the carbon layer. The magnetic couplings between the\nadsorbates show a strong dependence on the graphene sublattice of\nchemisorption. Molecules adsorbed at the same sublattice couple\nferromagnetically, with an exchange interaction that decays very slowly with\ndistance, while no magnetism is found for adsorbates at opposite sublattices.\nSimilar magnetic properties are obtained if several $p_z$ orbitals are\nsaturated simultaneously by the adsorption of a large molecule. These results\nmight open new routes to engineer the magnetic properties of graphene\nderivatives by chemical means."
    },
    {
        "anchor": "Antiresonances as precursors of decoherence: We show that, in presence of a complex spectrum, antiresonances act as a\nprecursor for dephasing enabling the crossover to a fully decoherent transport\neven within a unitary Hamiltonian description. This general scenario is\nillustrated here by focusing on a quantum dot coupled to a chaotic cavity\ncontaining a finite, but large, number of states using a Hamiltonian\nformulation. For weak coupling to a chaotic cavity with a sufficiently dense\nspectrum, the ensuing complex structure of resonances and antiresonances leads\nto phase randomization under coarse graining in energy. Such phase\ninstabilities and coarse graining are the ingredients for a mechanism producing\ndecoherence and thus irreversibility. For the present simple model one finds a\nconductance that coincides with the one obtained by adding a ficticious voltage\nprobe within the Landauer-Buettiker picture. This sheds new light on how the\nmicroscopic mechanisms that produce phase fluctuations induce decoherence.",
        "positive": "Single-Shot Readout Performance of Two Heterojunction-Bipolar-Transistor\n  Amplification Circuits at Millikelvin Temperatures: High-fidelity single-shot readout of spin qubits requires distinguishing\nstates much faster than the T1 time of the spin state. One approach to\nimproving readout fidelity and bandwidth (BW) is cryogenic amplification, where\nthe signal from the qubit is amplified before noise sources are introduced and\nroom-temperature amplifiers can operate at lower gain and higher BW. We compare\nthe performance of two cryogenic amplification circuits: a current-biased\nheterojunction bipolar transistor circuit (CB-HBT), and an AC-coupled HBT\ncircuit (AC-HBT). Both circuits are mounted on the mixing-chamber stage of a\ndilution refrigerator and are connected to silicon metal oxide semiconductor\n(Si-MOS) quantum dot devices on a printed circuit board (PCB). The power\ndissipated by the CB-HBT ranges from 0.1 to 1 {\\mu}W whereas the power of the\nAC-HBT ranges from 1 to 20 {\\mu}W. Referred to the input, the noise spectral\ndensity is low for both circuits, in the 15 to 30 fA/$\\sqrt{\\textrm{Hz}}$\nrange. The charge sensitivity for the CB-HBT and AC-HBT is 330\n{\\mu}e/$\\sqrt{\\textrm{Hz}}$ and 400 {\\mu}e/$\\sqrt{\\textrm{Hz}}$, respectively.\nFor the single-shot readout performed, less than 10 {\\mu}s is required for both\ncircuits to achieve bit error rates below $10^{-3}$, which is a putative\nthreshold for quantum error correction."
    },
    {
        "anchor": "Towards quantum dot arrays of entangled photon emitters: We show that with a new family of pyramidal site-controlled InGaAsN quantum\ndots it is possible to obtain areas containing as much as 15% of\npolarization-entangled photon emitters - a major improvement if compared to the\nsmall fraction achievable by other quantum dot systems. Entanglement is\nattested by a two-photon polarization state density matrix and the parameters\nobtained from it. Emitters showing fidelities up to 0.721+-0.043 were found.",
        "positive": "Electric Field Tuning of the Surface Band Structure of Topological\n  Insulator Sb2Te3 Thin Films: We measured the response of the surface state spectrum of epitaxial Sb2Te3\nthin films to applied gate electric fields by low temperature scanning\ntunneling microscopy. The gate dependent shift of the Fermi level and the\nscreening effect from bulk carriers vary as a function of film thickness. We\nobserved a gap opening at the Dirac point for films thinner than four quintuple\nlayers, due to the coupling of the top and bottom surfaces. Moreover, the top\nsurface state band gap of the three quintuple layer films was found to be\ntunable by back gate, indicating the possibility of observing a topological\nphase transition in this system. Our results are well explained by an effective\nmodel of 3D topological insulator thin films with structure inversion\nasymmetry, indicating that three quintuple layer Sb2Te3 films are topologically\nnontrivial and belong to the quantum spin Hall insulator class."
    },
    {
        "anchor": "Resonant spin wave excitation in magnetoplasmonic bilayers by short\n  laser pulses: In magnetically ordered solids a static magnetic field can be generated by\nvirtue of the transverse magneto-optical Kerr effect (TMOKE). Moreover, the\nlatter was shown to be dramatically enhanced due to the optical excitation of\nsurface plasmons in nanostructures with relatively small optical losses. In\nthis paper we suggest a new method of resonant optical excitations in a\nprototypical bilayer composed of noble metal (Au) with grating and a\nferromagnet thin film of yttrium iron garnet (YIG) via frequency comb. Based on\nmagnetization dynamics simulations we show that for the frequency comb with the\nparameters, chosen in resonant with spin-wave excitations of YIG, TMOKE is\ndrastically enhanced, hinting towards possible technological applications in\nthe optical control of spintronics systems.",
        "positive": "Controlled nucleation of topological defects in the stripe domain\n  patterns of Lateral multilayers with Perpendicular Magnetic Anisotropy:\n  competition between magnetostatic, exchange and misfit interactions: Magnetic lateral multilayers have been fabricated on weak perpendicular\nmagnetic anisotropy amorphous Nd-Co films in order to perform a systematic\nstudy on the conditions for controlled nucleation of topological defects within\ntheir magnetic stripe domain pattern. A lateral thickness modulation of period\n$w$ is defined on the nanostructured samples that, in turn, induces a lateral\nmodulation of both magnetic stripe domain periods $\\lambda$ and average\nin-plane magnetization component $M_{inplane}$. Depending on lateral multilayer\nperiod and in-plane applied field, thin and thick regions switch independently\nduring in-plane magnetization reversal and domain walls are created within the\nin-plane magnetization configuration coupled to variable angle grain boundaries\nand disclinations within the magnetic stripe domain patterns. This process is\nmainly driven by the competition between rotatable anisotropy (that couples the\nmagnetic stripe pattern to in-plane magnetization) and in-plane shape\nanisotropy induced by the periodic thickness modulation. However, as the\nstructural period $w$ becomes comparable to magnetic stripe period $\\lambda$,\nthe nucleation of topological defects at the interfaces between thin and thick\nregions is hindered by a size effect and stripe domains in the different\nthickness regions become strongly coupled."
    },
    {
        "anchor": "The effect of layer number and substrate on the stability of graphene\n  under MeV proton beam irradiation: The use of graphene electronics in space will depend on the radiation\nhardness of graphene. The damage threshold of graphene samples, subjected to 2\nMeV proton irradiation, was found to increase with layer number and also when\nthe graphene layer was supported by a substrate. The thermal properties of\ngraphene as a function of the number of layers or as influenced by the\nsubstrate argue against a thermal model for the production of damage by the ion\nbeam. We propose a model of intense electronically-stimulated surface\ndesorption of the atoms as the most likely process for this damage mechanism.",
        "positive": "High field magneto-transport in high mobility gated InSb/InAlSb quantum\n  well heterostructures: We present high field magneto-transport data from a range of 30nm wide\nInSb/InAlSb quantum wells. The low temperature carrier mobility of the samples\nstudied ranged from 18.4 to 39.5 m2V-1s-1 with carrier densities between\n1.5x1015 and 3.28x1015 m-2. Room temperature mobilities are reported in excess\nof 6 m2V-1s-1. It is found that the Landau level broadening decreases with\ncarrier density and beating patterns are observed in the magnetoresistance with\nnon-zero node amplitudes in samples with the narrowest broadening despite the\npresence of a large g-factor. The beating is attributed to Rashba splitting\nphenomenon and Rashba coupling parameters are extracted from the difference in\nspin populations for a range of samples and gate biases. The influence of\nLandau level broadening and spin-dependent scattering rates on the observation\nof beating in the Shubnikov-de Haas oscillations is investigated by simulations\nof the magnetoconductance. Data with non-zero beat node amplitudes are\naccompanied by asymmetric peaks in the Fourier transform, which are\nsuccessfully reproduced by introducing a spin-dependent broadening in the\nsimulations. It is found that the low-energy (majority) spin up state suffers\nmore scattering than the high-energy (minority) spin down state and that the\nabsence of beating patterns in the majority of (lower density) samples can be\nattributed to the same effect when the magnitude of the level broadening is\nlarge."
    },
    {
        "anchor": "Electric transport through circular graphene quantum dots: Presence of\n  disorder: The electronic states of an electrostatically confined cylindrical graphene\nquantum dot and the electric transport through this device are studied\ntheoretically within the continuum Dirac-equation approximation and compared\nwith numerical results obtained from a tight-binding lattice description. A\nspectral gap, which may originate from strain effects, additional adsorbed\natoms or substrate-induced sublattice-symmetry breaking, allows for bound and\nscattering states. As long as the diameter of the dot is much larger than the\nlattice constant, the results of the continuum and the lattice model are in\nvery good agreement. We also investigate the influence of a sloping\ndot-potential step, of on-site disorder along the sample edges, of uncorrelated\nshort-range disorder potentials in the bulk, and of random magnetic-fluxes that\nmimic ripple-disorder. The quantum dot's spectral and transport properties\ndepend crucially on the specific type of disorder. In general, the peaks in the\ndensity of bound states are broadened but remain sharp only in the case of edge\ndisorder.",
        "positive": "Magnetoresistance in Disordered Graphene: The Role of Pseudospin and\n  Dimensionality Effects Unraveled: We report a theoretical low-field magnetotransport study unveiling the effect\nof pseudospin in realistic models of weakly disordered graphene-based\nmaterials. Using an efficient Kubo computational method, and simulating the\neffect of charges trapped in the oxide, different magnetoconductance\nfingerprints are numerically obtained in system sizes as large as 0.3\nmicronmeter squared, containing tens of millions of carbon atoms. In\ntwo-dimensional graphene, a strong valley mixing is found to irreparably yield\na positive magnetoconductance (weak localization), whereas crossovers from\npositive to a negative magnetoconductance (weak antilocalization) are obtained\nby reducing disorder strength down to the ballistic limit. In sharp contrast,\ngraphene nanoribbons with lateral size as large as 10nm show no sign of weak\nantilocalization, even for very small disorder strength. Our results\nrationalize the emergence of a complex phase diagram of magnetoconductance\nfingerprints, shedding some new light on the microscopical origin of pseudospin\neffects."
    },
    {
        "anchor": "Nano-Cross-Junction Effect on Phonon Transport in Silicon-Nanowire-Cages: Wave effects of phonons can give rise to controllability of heat conduction\nbeyond that by particle scattering at surfaces and interfaces. In this work, we\npropose a new class of 3D nanostructure: a silicon-nanowire-cage (SiNWC)\nstructure consisting of silicon nanowires (SiNWs) connected by\nnano-cross-junctions (NCJs). We perform equilibrium molecular dynamics (MD)\nsimulations, and find an ultralow value of thermal conductivity of SiNWC, 0.173\nWm-1K-1, which is one order lower than that of SiNWs. By further modal analysis\nand atomistic Green's function calculations, we identify that the large\nreduction is due to significant phonon localization induced by the phonon local\nresonance and hybridization at the junction part in a wide range of phonon\nmodes. This localization effect does not require the cage to be periodic,\nunlike the phononic crystals, and can be realized in structures that are easier\nto synthesize, for instance in a form of randomly oriented SiNWs network.",
        "positive": "Electric field controlled spin- and valley-polarized edge states in\n  silicene with extrinsic Rashba effect: In the presence of extrinsic Rashba spin-orbit coupling, we find that\nsilicene can host a new quantum anomalous Hall state with spin- and\nvalley-polarized edge states, which can be effectively controlled by the\nexchange field and electric field. In this new state, the pair of nontrivial\nedge states reside in one specific valley and have a strong but opposite spin\npolarization. A distinctive feature of this new state is that both of the spin\nand valley index of the edge states can be switched by reversing the electric\nfield. We also present a microscopic mechanism for the origination of the new\nstate. Our findings provide an efficient way to control the topologically\nprotected spin- and valley-polarized edge states, which is crucial for\nspintronics and valleytronics."
    },
    {
        "anchor": "Generating single photons at GHz modulation-speed using electrically\n  controlled quantum dot microlenses: We report on the generation of single-photon pulse trains at a repetition\nrate of up to 1 GHz. We achieve this high speed by modulating the external\nvoltage applied on an electrically contacted quantum dot microlens, which is\noptically excited by a continuous-wave laser. By modulating the\nphotoluminescence of the quantum dot microlens using a square-wave voltage,\nsingle-photon emission is triggered with a response time as short as 270 ps\nbeing 6.5 times faster than the radiative lifetime of 1.75 ns. This large\nreduction in the characteristic emission time is enabled by a rapid capacitive\ngating of emission from the quantum dot placed in the intrinsic region of a\np-i-n-junction biased below the onset of electroluminescence. Here, the rising\nedge of the applied voltage pulses triggers the emission of single photons from\nthe optically excited quantum dot. The non-classical nature of the photon pulse\ntrain generated at GHz-speed is proven by intensity autocorrelation\nmeasurements. Our results combine optical excitation with fast electrical\ngating and thus show promise for the generation of indistinguishable single\nphotons at high rates, exceeding the limitations set by the intrinsic radiative\nlifetime.",
        "positive": "The radial breathing-like mode of the collapsed Single-walled carbon\n  nanotube bundle under hydrostatic pressure: Using the first principles calculations we have studied the vibrational modes\nand Raman spectra of a (10, 10) single-walled carbon nanotube (SWNT) bundle\nunder hydrostatic pressure. Detailed analysis shows that the original radial\nbreathing mode (RBM) of the SWNT bundle disappears after the structural phase\ntransition (SPT). And significantly a RBM-like mode appears at about 509\ncm^{-1}, which could be considered as a fingerprint of the SPT happened in the\nSWNT bundle, and further used to determine the microscopic structure of the\nbundle after the SPT."
    },
    {
        "anchor": "Purely magnetic logic based on polarized spin waves: Spin wave, the precession of magnetic order in magnetic materials, is a\ncollective excitation that carries spin angular momentum. Similar to the\nacoustic or optical waves, the spin wave also possesses the polarization degree\nof freedom. Although such polarization degrees of freedom are frozen in\nferromagnets, they are fully unlocked in antiferromagnets or ferrimagnets. Here\nwe introduce the concept of magnetic gating and demonstrate a spin wave analog\nof the Datta-Das spin transistor in antiferromagnet. Utilizing the interplay\nbetween polarized spin wave and the antiferromagnetic domain walls, we propose\na universal logic gate of pure magnetic nature, which realizes all Boolean\noperations in one single magnetic structure. We further construct a full\nfunctional 4-bit Arithmetic Logic Unit using only sixteen spin wave universal\nlogic gates, operating in a weaving fashion as a Jacquard loom machine. The\nspin wave-based architecture proposed here also sets a model for the future\nenergy efficient non-volatile computing, the distributed processing-in-memory\ncomputing, and the evolvable neuromorphic computing.",
        "positive": "Probing the spin-polarized electronic band structure in monolayer\n  transition metal dichalcogenides by optical spectroscopy: We study the electronic band structure in the K/K' valleys of the Brillouin\nzone of monolayer WSe2 and MoSe2 by optical reflection and photoluminescence\nspectroscopy on dual-gated field-effect devices. Our experiment reveals the\ndistinct spin polarization in the conduction bands of these compounds by a\nsystematic study of the doping dependence of the A and B excitonic resonances.\nElectrons in the highest-energy valence band and the lowest-energy conduction\nband have antiparallel spins in monolayer WSe2, and parallel spins in monolayer\nMoSe2. The spin splitting is determined to be hundreds of meV for the valence\nbands and tens of meV for the conduction bands, which are in good agreement\nwith first principles calculations. These values also suggest that both n- and\np-type WSe2 and MoSe2 can be relevant for spin- and valley-based applications"
    },
    {
        "anchor": "Locking and unlocking of the counterflow transport in nu=1 quantum Hall\n  bilayers by tilting of magnetic field: The counterflow transport in quantum Hall bilayers provided by superfluid\nexcitons is locked at small input currents due to a complete leakage caused by\nthe interlayer tunneling. We show that the counterflow critical current\nI_c^{CF} above which the system unlocks for the counterflow transport can be\ncontrolled by a tilt of magnetic field in the plane perpendicular to the\ncurrent direction. The effect is asymmetric with respect to the tilting angle.\nThe unlocking is accompanied by switching of the systems from the d.c. to the\na.c. Josephson state. Similar switching takes place for the tunneling set-up\nwhen the current flowing through the system exceeds the critical value I_c^T.\nAt zero tilt the relation between the tunnel and counterflow critical currents\nis I_c^T=2 I_c^{CF}. We compare the influence of the in-plane magnetic field\ncomponent B_\\parallel on the critical currents I_c^{CF} and I_c^T. The in-plane\nmagnetic field reduces the tunnel critical current and this reduction is\nsymmetric with respect to the tilting angle. It is shown that the difference\nbetween I_c^{CF} and I_c^T is essential at field |B_\\parallel|\\lesssim \\phi_0/d\n\\lambda_J, where \\phi_0 is the flux quantum, d is the interlayer distance, and\n\\lambda_J is the Josephson length. At larger B_\\parallel the critical currents\nI_c^{CF} and I_c^T almost coincide each other.",
        "positive": "Thermalization Effect in semiconductor Si, and metallic silicide NiSi2,\n  CoSi2 by using Non-Adiabatic Molecular Dynamics Approach: Recently, cold source transistor (CSFET) with steep-slope subthreshold swing\n(SS) < 60 mV/decade has been proposed to overcome Boltzmann tyranny in its\nballistic regime. However the scattering, especially by inelastic scattering\nmay lead serious SS degradation through cold carrier thermalization. In this\nstudy, the electronic excitation/relaxation dynamic process is investigated\ntheoretically by virtue of the state-of-the-art nonadiabatic molecular dynamics\n(NAMD) method, i.e., the mixed quantum-classical NAMD. The mixed\nquantum-classical NAMD considers both carrier decoherence and detailed balance\nto calculate the cold carrier thermalization and transfer processes in\nsemiconductor Si, and metallic silicide (NiSi2 and CoSi2). The dependence of\nthe thermalization factor, relaxation time, scattering time and scattering rate\non energy level are obtained. The thermalization of carrier gradually increases\nfrom low energy to high energy. Partially thermalization from the ground state\nto reach the thermionic current window is realized with sub-100 $fs$ time\nscale. Fully thermalization to entail energy region depends on the barrier\nheight sensitively, i.e., the scattering rate decreases exponentially as the\nenergy of the out-scattering state increase. The scattering rate of NiSi2 and\nCoSi2 is 2 orders of magnitude higher than that of Si, arising from their\nhigher density of states than that in Silicon This study can shed light on the\nmaterial design for low power tunneling FET as well as the emerging CSFET."
    },
    {
        "anchor": "Reducing strain fluctuations in quantum dot devices by gate-layer\n  stacking: Nanofabricated metal gate electrodes are commonly used to confine and control\nelectrons in electrostatically defined quantum dots. However, these same gates\nimpart a complicated strain geometry that affects the confinement potential and\npotentially impairs device functionality. Here we investigate strain-induced\nfluctuations of the potential energy in Si/SiGe heterostructures, caused by (i)\nlattice mismatch, (ii) materials-dependent thermal contraction, and (iii)\ndeposition stress in the metal gates. By simulating different gate geometries,\nranging from simple to realistically complicated, and including features like\noverlapping metal and oxide layers, we can explain most observed strain\nfeatures. In particular, we show that strain-induced potential fluctuations can\nbe suppressed by employing overlapping gates that cover the whole active\nregion, when the oxide layers are thin. These results suggest that strain\neffects should not present a serious challenge to qubit uniformity when\nfollowing simple design rules.",
        "positive": "Effective theory of rotationally faulted multilayer graphene - the local\n  limit: Interlayer coupling in rotationally faulted graphene multilayers breaks the\nlocal sublattice-symmetry of the individual layers. Earlier we have presented a\ntheory of this mechanism, which reduces to an effective Dirac model with\nspace-dependent mass in an important limit. It thus makes a wealth of existing\nknowledge available for the study of rotationally faulted graphene multilayers.\nAgreement of this theory with a recent experiment in a strong magnetic field\nwas demonstrated. Here we explore some of the predictions of this theory for\nthe system in zero magnetic field at large interlayer bias, when it becomes\nlocal in space. We use that theory to illuminate the physics of localization\nand velocity renormalization in twisted graphene bilayers."
    },
    {
        "anchor": "Flat Bands in Slightly Twisted Bilayer Graphene: The bands of graphite are extremely sensitive to topological defects which\nmodify the electronic structure. In this paper we found non-dispersive flat\nbands no farther than 10 meV of the Fermi energy in slightly twisted bilayer\ngraphene as a signature of a transition from a parabolic dispersion of bilayer\ngraphene to the characteristic linear dispersion of graphene. This transition\noccurs for relative rotation angles of layers around $1.5^o$ and is related to\na process of layer decoupling.\n  We have performed ab-initio calculations to develop a tight binding model\nwith an interaction Hamiltonian between layers that includes the $\\pi$ orbitals\nof all atoms and takes into account interactions up to third nearest-neighbors\nwithin a layer.",
        "positive": "A current-voltage characteristic of photoresistance. A plane case: The formation of photo-electron current in the volume of semi-conductor\nmaterial is investigated in this article. A plane case when a material is\nuniformly illuminated by light is considered. The current-voltage\ncharacteristic of a photo resistance is obtained in analytical form."
    },
    {
        "anchor": "Graphene-Based Non-Boolean Logic Circuits: Graphene revealed a number of unique properties beneficial for electronics.\nHowever, graphene does not have an energy band-gap, which presents a serious\nhurdle for its applications in digital logic gates. The efforts to induce a\nband-gap in graphene via quantum confinement or surface functionalization have\nnot resulted in a breakthrough. Here we show that the negative differential\nresistance experimentally observed in graphene field-effect transistors of\n\"conventional\" design allows for construction of viable non-Boolean\ncomputational architectures with the gap-less graphene. The negative\ndifferential resistance - observed under certain biasing schemes - is an\nintrinsic property of graphene resulting from its symmetric band structure. Our\natomistic modeling shows that the negative differential resistance appears not\nonly in the drift-diffusion regime but also in the ballistic regime at the\nnanometer-scale - although the physics changes. The obtained results present a\nconceptual change in graphene research and indicate an alternative route for\ngraphene's applications in information processing.",
        "positive": "Nonlinear chiral refrigerators: We investigate a mesoscopic refrigerator based on chiral quantum Hall edge\nchannels. We discuss a three-terminal cooling device in which charge transport\noccurs between a pair of voltage-biased terminals only. The third terminal,\nwhich is to be cooled, is set as a voltage probe with vanishing particle flux.\nThis largely prevents the generation of direct Joule heating which ensures a\nhigh coefficient of performance. Cooling operation is based on energy-dependent\nquantum transmissions. The latter are implemented with the aid of two tunable\nscattering resonances (quantum dots). To find the optimal performance point and\nthe largest temperature difference created with our refrigerator, it is crucial\nto address the nonlinear regime of transport, accounting for electron-electron\ninteraction effects. Our numerical simulations show that the maximal cooling\npower can be tuned with the quantum dot couplings and energy levels. Further,\nwe provide analytical expressions within a weakly nonlinear scattering-matrix\nformalism which allow us to discuss the conditions for optimal cooling in terms\nof generalized thermopowers. Our results are important for the assessment of\nchiral conductors as promising candidates for efficient quantum refrigerators\nwith low dissipation."
    },
    {
        "anchor": "Low-frequency divergence and quantum geometry of the bulk photovoltaic\n  effect in topological semimetals: We study the low-frequency properties of the bulk photovoltaic effect in\ntopological semimetals. The bulk photovoltaic effect is a nonlinear optical\neffect that generates DC photocurrents under uniform irradiation, allowed by\nnoncentrosymmetry. It is a promising mechanism for a terahertz photodetection\nbased on topological semimetals. Here, we systematically investigate the\nlow-frequency behavior of the second-order optical conductivity in point-node\nsemimetals. Through symmetry and power-counting analysis, we show that Dirac\nand Weyl points with tilted cones show the leading low-frequency divergence. In\nparticular, we find new divergent behaviors of the conductivity of Dirac and\nWeyl points under circularly polarized light, where the conductivity scales as\n$\\omega^{-2}$ and $\\omega^{-1}$ near the gap-closing point in two and three\ndimensions, respectively. We provide a further perspective on the low-frequency\nbulk photovoltaic effect by revealing the complete quantum geometric meaning of\nthe second-order optical conductivity tensor. The bulk photovoltaic effect has\ntwo origins, which are the transition of electron position and the transition\nof electron velocity during the optical excitation, and the resulting\nphotocurrents are respectively called the shift current and the injection\ncurrent. Based on an analysis of two-band models, we show that the injection\ncurrent is controlled by the quantum metric and Berry curvature, whereas the\nshift current is governed by the Christoffel symbols near the gap-closing\npoints in semimetals. Finally, for further demonstrations of our theory beyond\nsimple two-band models, we perform first-principles calculations on magnetic\nDirac semimetal MnGeO$_3$and Weyl semimetal PrGeAl. Our work brings out new\ninsights into the structure of nonlinear optical responses as well as for the\ndesign of semimetal-based terahertz photodetectors.",
        "positive": "Charge-to-spin conversion efficiency in ferromagnetic nanowires by spin\n  torque ferromagnetic resonance: Reconciling lineshape and linewidth analysis\n  methods: Spin orbit torques are of great interest for switching the magnetization\ndirection in nanostructures, moving skyrmions and exciting spin waves. The\nstandard method of determining their efficiency is by spin torque ferromagnetic\nresonance (ST-FMR), a technique that involves analyzing the resonance linewidth\nor lineshape. On microstuctures these two analysis methods are quite\nconsistent. Here we present ST-FMR results on permalloy (Ni$_{80}$Fe$_{20}$)\nnanowires -- with widths varying from $150$ to 800 nm -- that show that the\nstandard model used to analyze the resonance linewidth and lineshape give\ndifferent results; the efficiency appears greatly enhanced in nanowires when\nthe lineshape method is used. A ST-FMR model that properly accounts for the\nsample shape is presented and shows much better consistency between the two\nmethods. Micromagnetic simulations are used to verify the model. These results\nand the more accurate nanowire model presented are of importance for\ncharacterizing and optimizing charge-to-spin conversion efficiencies in\nnanostructures."
    },
    {
        "anchor": "Quantum Andreev effect in 2D HgTe/CdTe quantum well-superconductor\n  systems: The Andreev reflection (AR) in 2D HgTe/CdTe quantum well-superconductor\nhybrid systems is studied. A quantized AR with AR coefficient equal to one is\npredicted, which is due to the multi-Andreev reflection near the interface of\nthe hybrid system. Importantly, this quantized AR is not only universal, i.e.,\nindependent of any system parameters and quality of the coupling of the hybrid\nsystem, it is also robust against disorder as well. As a result of this quantum\nAndreev effect, the conductance exhibits a quantized plateau when the external\nbias is less the superconductor gap.",
        "positive": "Spin relaxation and donor-acceptor recombination of Se$^+$ in 28-silicon: Selenium impurities in silicon are deep double donors and their optical and\nelectronic properties have been recently investigated due to their application\nfor infrared detection. However, a singly-ionised selenium donor (Se$^{+}$)\npossesses an electron spin which makes it a potential candidate as a\nsilicon-based spin qubit, with significant potential advantages compared to the\nmore commonly studied group V donors. Here we study the electron spin\nrelaxation ($T_1$) and coherence ($T_2$) times of Se$^{+}$ in isotopically\npurified 28-silicon, and find them to be up to two orders of magnitude longer\nthan shallow group V donors at temperatures above $\\sim 15$ K. We further study\nthe dynamics of donor-acceptor recombination between selenium and boron,\ndemonstrating that it is possible to control the donor charge state through\noptical excitation of neutral Se$^0$."
    },
    {
        "anchor": "Quantum-interference origin and magnitude of 1/$f$ noise in Dirac nodal\n  line IrO$_2$ nanowires at low temperatures: We present 1/$f$ noise measurements of IrO$_2$ nanowires from 1.7 to 350 K.\nResults reveal that the noise magnitude (represented by Hooge parameter\n$\\gamma$) increases at low temperatures, indicating low-frequency resistance\nnoise from universal conductance fluctuations. The cause of this noise is\ndetermined to be due to oxygen vacancies in the rutile structure of IrO$_2$.\nAdditionally, the number density of these mobile defects can be calculated from\nthe $\\sqrt{T}$ resistance rise caused by the orbital two-channel Kondo effect\nin the Dirac nodal line metal IrO$_2$.",
        "positive": "Condensed Matter Laboratory: new application for quantum simulation: The purpose of this paper is to introduce Condensed-Matter-Laboratory (CML)\napplication for simulating solids and nanostructures and calculating different\nproperties of them by density functional theory and using Green's function\ntheory in tight-binding approximation to calculate phononic and spin dependent\nor independent electronic properties of different systems. Also, it can be used\nfor calculating thermodynamic properties of solids and nanostructures using\nstatistical mechanics. The CML is a cross-platform application with a graphical\nuser interface design that is user-friendly and easy to work with. This\napplication is written in c++ and fortran and has parallel processing ability.\nTo show flexibility of this application some reasons are presented."
    },
    {
        "anchor": "Quasi-particle description for the transport through a small interacting\n  system: We study effects of electron correlation on the transport through a small\ninteracting system connected to reservoirs using an effective Hamiltonian which\ndescribes the free quasi-particles of a Fermi liquid. The effective Hamiltonian\nis defined microscopically with the value of the self-energy at $\\omega=0$.\nSpecifically, we apply the method to a Hubbard chain of finite size $N$ ($=1,\n2, 3, ...$), and calculate the self-energy within the second order in $U$ in\nthe electron-hole symmetric case. When the couplings between the chain and the\nreservoirs on the left and right are small, the conductance for even $N$\ndecreases with increasing $N$ showing a tendency toward a Mott-Hubbard\ninsulator. This is caused by the off-diagonal element of the self-energy, and\nthis behavior is qualitatively different from that in the special case examined\nin the previous work. We also study the effects of the asymmetry in the two\ncouplings. While the perfect transmission due to the Kondo resonance occurs for\nany odd $N$ in the symmetric coupling, the conductance for odd $N$ decreases\nwith increasing $N$ in the case of the asymmetric coupling.",
        "positive": "Phase-separated high-temperature-annealed (Ga,Mn)As: A negative\n  charge-transfer-energy material: The approximate location in the Zaanen-Sawatzky-Allen diagram of the\nphase-separated (Ga,Mn)As material, consisting of MnAs nanoclusters embedded in\nGaAs, is determined on the basis of configuration-interaction (CI)\ncluster-model analysis of their Mn 2p core-level photoemission. The composite\nmaterial is found to belong to the special class of materials with negative\ncharge-transfer energy (delta). As such, its metallic or\ninsulating/semiconducting behavior depends on the strength of the p-d\nhybridization (affected by strain) relative to the (size-dependent)\np-bandwidth. Whereas internal strain in the embedded clusters counteracts gap\nopening, a metal-to-semiconductor transition is expected to occur for\ndecreasing cluster size, associated to the opening of a small gap of p-p type\n(covalent gap). The electronic properties of homogeneous and phase-separated\n(Ga,Mn)As materials are analyzed, with emphasis on the nature of their\nmetal-insulator transitions."
    },
    {
        "anchor": "Valley dynamics probed through charged and neutral exciton emission in\n  monolayer WSe2: Optical interband transitions in monolayer transition metal dichalcogenides\nsuch as WSe2 and MoS2 are governed by chiral selection rules. This allows\nefficient optical initialization of an electron in a specific K-valley in\nmomentum space. Here we probe the valley dynamics in monolayer WSe2 by\nmonitoring the emission and polarization dynamics of the well separated neutral\nexcitons (bound electron hole pairs) and charged excitons (trions) in\nphotoluminescence. The neutral exciton photoluminescence intensity decay time\nis about 4ps, whereas the trion emission occurs over several tens of ps. The\ntrion polarization dynamics shows a partial, fast initial decay within tens of\nps before reaching a stable polarization of about 20%, for which a typical\nvalley polarization decay time larger than 1ns can be inferred. This is a clear\nsignature of stable, optically initialized valley polarization.",
        "positive": "Magnetism in one-dimensional quantum dot arrays: We employ the density functional Kohn-Sham method in the local spin-density\napproximation to study the electronic structure and magnetism of quasi\none-dimensional periodic arrays of few-electron quantum dots. At small values\nof the lattice constant, the single dots overlap, forming a non-magnetic\nquantum wire with nearly homogenous density. As the confinement perpendicular\nto the wire is increased, i.e. as the wire is squeezed to become more\none-dimensional, it undergoes a spin-Peierls transition. Magnetism sets in as\nthe quantum dots are placed further apart. It is determined by the electronic\nshell filling of the individual quantum dots. At larger values of the lattice\nconstant, the band structure for odd numbers of electrons per dot indicates\nthat the array could support spin-polarized transport and therefore act as a\nspin filter."
    },
    {
        "anchor": "The impact of interface modification on the behavior of phenyl alcohols\n  within silica templates: Herein, thermal, dynamical properties, host-guest intermolecular\ninteractions, and wettability of a series of monohydroxy phenyl-substituted\nalcohols (PhAs) infiltrated into native and silanized silica mesopores (d = 4\nnm) were investigated by means of Dielectric and Infrared (IR) Spectroscopy,\nDifferential Scanning Calorimetry as well as the contact angle measurements.\nCalorimetric data showed the occurrence of the two glass transition\ntemperatures, Tg. Importantly, around the one detected at higher temperatures\n(Tg interfacial), strong deviation in the temperature evolution of the\nrelaxation time of the main process was observed for all systems. Moreover, an\nadditional process unrelated to the mobility of interface layer and core\nmolecules was revealed most likely connected to either SAP or \"new\"\nconfinement-induced nanoassociates. Further, IR investigations showed that the\napplied nanoconfinement had little impact on hydrogen bonds' strength, but it\ninfluenced the HBs distribution (including \"new\" population of HB) and the\ndegree of association. Additionally, for the first time, we calculated the\nactivation energy values of the dissociation process for PhAs in mesopores,\nwhich turned out to be lower with respect to those estimated for bulk samples.\nThus, our research clearly showed the impact of the spatial geometrical\nrestriction on the association process in alcohols having significant steric\nhindrance.",
        "positive": "Anisotropic transport for $\u03bd=2/5$ FQH state at intermediate magnetic\n  field: The $\\nu=2/5$ state is spin-unpolarized at weak magnetic field and fully\npolarized at strong field. At intermediate field, a plateau of half the maximal\npolarization is observed. We study this phenomenon in the frame of composite\nfermion theory. Due to the mixing of the composite fermion Landau levels, the\nunidirectional charge/spin density wave state of composite fermions is lower in\nenergy than the Wigner crystal. It means that transport anisotropy, similar to\nthose for electrons in higher Landau levels at half fillings, may take place at\nthis fractional quantum Hall state when the external magnetic field is in an\nappropriate range. When the magnetic field is tilted an angle, the easy\ntransport direction is perpendicular to the direction of the in-plane field.\nVarying the partial filling factor of composite fermion Landau level from 0 to\n1, we find that the energy minimum occurs in the vicinity of one-half."
    },
    {
        "anchor": "Interference of magnetointersubband and phonon-induced resistance\n  oscillations in single GaAs quantum wells with two populated subbands: Low-temperature electron magnetotransport in single GaAs quantum wells with\ntwo populated subbands is studied at large filling factors.\nMagneto-inter-subband (MIS) and acoustic-phonon induced oscillations of the\ndissipative resistance are found to be coexisting but interfering substantially\nwith each other. The experiments show that amplitude of the MIS-oscillations\nenhances significantly by phonons, indicating \"constructive interference\"\nbetween the phonon scattering and the intersubband electron transitions.\nTemperature damping of the quantum oscillations is found to be related to\nbroadening of Landau levels caused by considerable electron-electron\nscattering.",
        "positive": "Localization-induced optical properties of monolayer transition-metal\n  dichalcogenides: Impurities play an important role during recombination processes in\nsemiconductors. Their important role is sharpened in atomically-thin\ntransition-metal dichalcogenides whose two-dimensional character renders\nelectrons and holes highly susceptible to localization caused by remote charged\nimpurities. We study a multitude of phenomena that arise from the interaction\nof localized electrons with excitonic complexes. Emphasis is given to the\namplification of the phonon-assisted recombination of biexcitons when it is\nmediated by localized electrons, showing that this mechanism can explain recent\nphotoluminescence experiments in ML-WSe$_2$. In addition, the magnetic-field\ndependence of this mechanism is analyzed. The results of this work point to (i)\nan intriguing coupling between the longitudinal-optical and homopolar phonon\nmodes that can further elucidate various experimental results, (ii) the physics\nbehind a series of localization-induced optical transitions in tungsten-based\nmaterials, and (iii) the importance of localization centers in facilitating the\ncreation of biexcitons and exciton-exciton annihilation processes."
    },
    {
        "anchor": "Playing graphene nanodrums: force spectroscopy of graphene on Ru(0001): Graphene, a thinnest material in the world, can form moire structures on\ndifferent substrates, including graphite, h-BN, or metal surfaces. In such\nsystems the structure of graphene, i. e. its corrugation, as well as its\nelectronic and elastic properties are defined by the combination of the system\ngeometry and local interaction strength at the interface. The corrugation in\nsuch structures on metals is heavily extracted from diffraction or local probe\nmicroscopy experiments and can be obtained only via comparison with theoretical\ndata, which usually simulate the experimental findings. Here we show that\ngraphene corrugation on metals can be measured directly employing atomic force\nspectroscopy and obtained value coincides with state-of-the-art theoretical\nresults. We also address the elastic reaction of the formed graphene nanodoms\non the indentation process by the scanning tip that is important for the\nmodeling and fabrication of graphene-based nanoresonators on the nanoscale.",
        "positive": "Nonreciprocal Charge and Spin Transport Induced by Non-Hermitian Skin\n  Effect in Mesoscopic Heterojunctions: The pursuit of the non-Hermitian skin effect (NHSE) in various physical\nsystems is of great research interest. Compared with recent progress in\nnon-electronic systems, the implementation of the NHSE in condensed matter\nphysics remains elusive. Here, we show that the NHSE can be engineered in the\nmesoscopic heterojunctions (system plus reservoir) in which electrons in two\nchannels of the system moving towards each other have asymmetric coupling to\nthose of the reservoir. This makes electrons in the system moving forward and\nin the opposite direction have unequal lifetimes, and so gives rise to a\npoint-gap spectral topology. Accordingly, the electron eigenstates exhibit NHSE\nunder the open boundary condition, consistent with the description of the\ngeneralized Brillouin zone. Such a reservoir-engineered NHSE visibly manifests\nitself as the nonreciprocal charge current that can be probed by the standard\ntransport measurements. Further, we generalize the scenario to the\nspin-resolved NHSE, which can be probed by the nonreciprocal spin transport.\nOur work opens a new research avenue for implementing and detecting the NHSE in\nelectronic mesoscopic systems, which will lead to interesting device\napplications."
    },
    {
        "anchor": "Fermion doubling theorems in 2D non-Hermitian systems for Fermi points\n  and exceptional points: The fermion doubling theorem plays a pivotal role in Hermitian topological\nmaterials. It states, for example, that Weyl points must come in pairs in\nthree-dimensional semimetals. Here, we present an extension of the doubling\ntheorem to non-Hermitian lattice Hamiltonians. We focus on two-dimensional\nnon-Hermitian systems without any symmetry constraints, which can host two\ndifferent types of topological point nodes, namely, (i) Fermi points and (ii)\nexceptional points. We show that these two types of protected point nodes obey\ndoubling theorems, which require that the point nodes come in pairs. To prove\nthe doubling theorem for exceptional points, we introduce a generalized winding\nnumber invariant, which we call the discriminant number. Importantly, this\ninvariant is applicable to any two-dimensional non-Hermitian Hamiltonian with\nexceptional points of arbitrary order, and moreover can also be used to\ncharacterize non-defective degeneracy points. Furthermore, we show that a\nsurface of a three-dimensional system can violate the non-Hermitian doubling\ntheorems, which implies unusual bulk physics.",
        "positive": "Distance-dependent sign-reversal in the Casimir-Lifshitz torque: The Casimir-Lifshitz torque between two biaxially polarizable anisotropic\nplanar slabs is shown to exhibit a non-trivial sign-reversal in its rotational\nsense. The critical distance $a_c$ between the slabs that marks this reversal\nis characterized by the frequency $\\omega_c\\!\\sim \\!c/2a_c$ at which the\nin-planar polarizabilities along the two principal axes are equal. The two\nmaterials seek to align their principal axes of polarizabilities in one\ndirection below $a_c$, while above $a_c$ their axes try to align rotated\nperpendicular relative to their previous minimum energy orientation. The\nsign-reversal disappears in the nonretarded limit. Our perturbative result,\nderived for the case when the differences in the relative polarizabilities are\nsmall, matches excellently with the exact theory for uniaxial materials. We\nillustrate our results for black phosphorus and phosphorene."
    },
    {
        "anchor": "Dispersive Drumhead States in Nodal-Line Semimetal Junctions: We consider a smooth interface between a topological nodal-line semimetal and\na topologically trivial insulator (e.g., the vacuum) or another semimetal with\na nodal ring of different radius. Using a low-energy effective Hamiltonian\nincluding only the two crossing bands, we show that these junctions accommodate\na two-dimensional zero-energy level and a set of two-dimensional dispersive\nbands, corresponding to states localized at the interface. We characterize the\nspectrum, identifying the parameter ranges in which these states are present,\nand highlight the role of the nodal radius and the smoothness of the interface.\nWe also suggest material-independent ways to detect and identify these states,\nusing optical conductivity and infrared absorption spectroscopy in magnetic\nfield.",
        "positive": "Extremely confined gap plasmon modes: when nonlocality matters: Historically, the field of plasmonics has been relying on the framework of\nclassical electrodynamics, with the local-response approximation of material\nresponse being applied even when dealing with nanoscale metallic structures.\nHowever, when approaching the atomic-scale confinement of the electromagnetic\nradiation, mesoscopic effects are anticipated to become observable, e.g., those\nassociated with the nonlocal electrodynamic surface response of the electron\ngas. We investigate nonlocal effects in propagating gap surface plasmon modes\nin ultrathin metal--dielectric--metal planar waveguides, exploiting\nmonocrystalline gold flakes separated by atomic-layer-deposited aluminum oxide.\nWe use scanning near-field optical microscopy to directly access the near-field\nof such confined gap plasmon modes and measure their dispersion relation (via\ntheir complex-valued propagation constants). We compare our experimental\nfindings with the predictions of the generalized nonlocal optical response\ntheory to unveil signatures of nonlocal damping, which becomes appreciable for\nsmaller dielectric gaps."
    },
    {
        "anchor": "Spin polarization control by electric means: proposal for a spin diode: A scheme of spin diode is proposed that uses a step-like quantum wire with\nRashba spin-orbit interaction, connected to two leads with different width. It\nis shown that a very large vertical spin-polarized current can be generated\nwhen electrons transmit from the narrow lead to the wide lead, however, it\nvanishes or becomes very weak when the transport direction is reversed. This\ndifference is revealed to arise from the different local density of electron\nstates of the quantum wire, which is dependent on the direction of bias. The\nspin-polarized current in the proposed structure can be generated and\nmanipulated by purely electric means and with strong a robustness against\ndisorder, displaying the feasibility of this structure for a real application.",
        "positive": "General theory of topological Hall effect in systems with chiral spin\n  textures: We present a consistent theory of the topological Hall effect (THE) in 2D\nmagnetic systems with disordered array of chiral spin textures, such as\nmagnetic skyrmions. We focus on the scattering regime when the mean-free path\nof itinerant electrons exceeds the spin texture size, and THE arises from the\nasymmetric carrier scattering on individual chiral spin textures. We calculate\nthe resistivity tensor on the basis of the Boltzmann kinetic equation taking\ninto account the asymmetric scattering on skyrmions via the collision integral.\nOur theory describes both the adiabatic regime, when THE arises from a spin\nHall effect and the non-adiabatic scattering when THE is due to purely charge\ntransverse currents. We analyze the dependence of THE resistivity on a chiral\nspin texture structure,as well as on material parameters. We discuss the\ncrossover between spin and charge regimes of THE driven by the increase of\nskyrmion size, the features of THE due to the variation of the Fermi energy,\nand the exchange interaction strength; we comment on the sign and magnitude of\nTHE"
    },
    {
        "anchor": "Synthetic electric fields and phonon damping in carbon nanotubes and\n  graphene: Smoothly varying lattice strain in graphene affects the Dirac carriers\nthrough a synthetic gauge field. When the lattice strain is time dependent, as\nin connection with phononic excitations, the gauge field becomes time dependent\nand the synthetic vector potential is also associated with an electric field.\nWe show that this synthetic electric field has observable consequences. Joule\nheating associated with the currents driven by the synthetic electric field\ndominates the intrinsic damping, caused by the electron-phonon interaction, of\nmany acoustic phonon modes of graphene and metallic carbon nanotubes when\nincluding the effects of disorder and Coulomb interactions. Several important\nconsequences follow from the observation that by time-reversal symmetry, the\nsynthetic electric field associated with the vector potential has opposite\nsigns for the two valleys. First, this implies that the synthetic electric\nfield drives charge-neutral valley currents and is therefore unaffected by\nscreening. This frequently makes the effects of the synthetic vector potential\nmore relevant than a competing effect of the scalar deformation potential which\nhas a much larger bare coupling constant. Second, valley currents decay by\nelectron-electron scattering (valley Coulomb drag) which causes interesting\ntemperature dependence of the damping rates. While our theory pertains first\nand foremost to metallic systems such as doped graphene and metallic carbon\nnanotubes, the underlying mechanisms should also be relevant for semiconducting\ncarbon nanotubes when they are doped.",
        "positive": "Magnetocrystalline anisotropy controlled local magnetic configurations\n  in (Ga,Mn)As spin-transfer-torque microdevices: The large saturation magnetization in conventional dense moment ferromagnets\noffers flexible means of manipulating the ordered state through demagnetizing\nshape anisotropy fields but these dipolar fields, in turn, limit the\nintegrability of magnetic elements in information storage devices. We show that\nin a (Ga,Mn)As dilute moment ferromagnet, with comparatively weaker magnetic\ndipole interactions, locally tunable magnetocrystalline anisotropy can take the\nrole of the internal field which determines the magnetic configuration.\nExperiments and theoretical modeling are presented for lithographically\npatterned microchannels and the phenomenon is attributed to lattice relaxations\nacross the channels. The utility of locally controlled magnetic anisotropies is\ndemonstrated in current induced switching experiments. We report structure\nsensitive, current induced in-plane magnetization switchings well below the\nCurie temperature at critical current densities 10^5 Acm^-2. The observed\nphenomenology shows signatures of a contribution from domain-wall\nspin-transfer-torque effects."
    },
    {
        "anchor": "Shape-sensitive Pauli blockade in a bent carbon nanotube: Motivated by a recent experiment [F. Pei et al., Nat. Nanotech. 7, 630\n(2012)], we theoretically study the Pauli blockade transport effect in a double\nquantum dot embedded in a bent carbon nanotube. We establish a model for Pauli\nblockade, taking into account the strong g-factor anisotropy that is linked to\nthe local orientation of the nanotube axis in each quantum dot. We provide a\nset of conditions under which our model is approximately mapped to the\nspin-blockade model of Jouravlev and Nazarov [O. N. Jouravlev and Y. V.\nNazarov, Phys. Rev. Lett. 96, 176804 (2006)]. The results we obtain for the\nmagnetic anisotropy of the leakage current, together with their qualitative\ngeometrical explanation, provide a possible interpretation of previously\nunexplained experimental results. Furthermore, we find that in a certain\nparameter range, the leakage current becomes highly sensitive to the shape of\nthe tube, and this sensitivity increases with increasing g-factor anisotropy.\nThis mutual dependence of the electron transport and the tube shape allows for\nmechanical control of the leakage current, and for characterization of the tube\nshape via measuring the leakage current.",
        "positive": "Spaser as Novel Versatile Biomedical Tool: Fluorescence imaging and spectroscopy remain the most powerful tools for\nvisualization with chemical and immunological specificity of labeled\nbiomolecules, viruses, cellular organelles, and living cells in complex\nbiological backgrounds. However, a common drawback of fluorescence labels is\nthat their brightness is limited by optical saturation and photobleaching. As\nan alternative, plasmonic metal nanoparticles are very promising as optical\nlabels with no photobleaching and low optical saturation at realistic exciting\nintensities as was demonstrated in photoacoustic and photothermal sensing,\nimaging, and theranostics. However, plasmonic nanoparticles have wide\nabsorption spectra and are not fluorescent, which limits their spectral\nselectivity and multimodal functionality, respectively. Here we demonstrate\nexperimentally, both in vitro and in vivo, that spaser (surface plasmon\namplification by stimulated emission of radiation) provides unprecedented\nefficiency as a versatile tool in biomedical research and applications. This is\ndue to the unique combination of intense near-monochromatic stimulated emission\nand strongly enhanced absorption, free of optical saturation. Using soluble and\nbiocompatible uranine dye as a gain medium surrounding the gold nanocore as a\nplasmonic resonator, we demonstrate unprecedented spaser stimulated emission\nintensity (\"giant spasing\") and a narrow spectral width (0.8 nm), which are\nmore than ~380-fold and ~30-fold, respectively, better than in quantum dots as\nthe best conventional fluorescent nanoprobes. At the same time, the plasmonic\nspaser nanocore served as excellent photoacoustic and photothermal contrast\nagents for imaging and nanobubble-based theranostics of cancer cells. This\nmakes the spasers, arguably, the best multifunctional, super-contrast,\nlow-toxicity optical probes in biomedical research, especially with\nsingle-pulse excitation."
    },
    {
        "anchor": "Statistics of Spin Fluctuations in Quantum Dots with Ising Exchange: We explore the effect of single-particle level fluctuations on the Stoner\ninstability in a QD with a strong spin-orbit coupling in the framework of the\nuniversal Hamiltonian with the Ising exchange interaction. We reduce the\nproblem to studying the statistics of extrema of a certain Gaussian process and\ndemonstrate that, in spite of the randomness of the single-particle levels, the\nlongitudinal spin susceptibility and all its moments diverge simultaneously at\nthe point of the Stoner instability which is determined by the standard\ncriterion involving the mean level spacing only.",
        "positive": "Geometric Landau-Zener interferometry in a superconducting charge pump: We propose a new type of interferometry, based on geometric phases\naccumulated by a periodically driven two-level system undergoing multiple\nLandau-Zener transitions. As a specific example, we study its implementation in\na superconducting charge pump. We find that interference patterns appear as a\nfunction of the pumping frequency and the phase bias, and clearly manifest\nthemselves in the pumped charge. We also show that the effects described should\npersist in the presence of realistic decoherence."
    },
    {
        "anchor": "Metaplastic and Energy-Efficient Biocompatible Graphene Artificial\n  Synaptic Transistors for Enhanced Accuracy Neuromorphic Computing: CMOS-based computing systems that employ the von Neumann architecture are\nrelatively limited when it comes to parallel data storage and processing. In\ncontrast, the human brain is a living computational signal processing unit that\noperates with extreme parallelism and energy efficiency. Although numerous\nneuromorphic electronic devices have emerged in the last decade, most of them\nare rigid or contain materials that are toxic to biological systems. In this\nwork, we report on biocompatible bilayer graphene-based artificial synaptic\ntransistors (BLAST) capable of mimicking synaptic behavior. The BLAST devices\nleverage a dry ion-selective membrane, enabling long-term potentiation, with\n~50 aJ/m^2 switching energy efficiency, at least an order of magnitude lower\nthan previous reports on two-dimensional material-based artificial synapses.\nThe devices show unique metaplasticity, a useful feature for generalizable deep\nneural networks, and we demonstrate that metaplastic BLASTs outperform ideal\nlinear synapses in classic image classification tasks. With switching energy\nwell below the 1 fJ energy estimated per biological synapse, the proposed\ndevices are powerful candidates for bio-interfaced online learning, bridging\nthe gap between artificial and biological neural networks.",
        "positive": "The Marginal Fermi Liquid - An Exact Derivation Based on Dirac's First\n  Class Constraints Method: Dirac's method for constraints is used for solving the problem of exclusion\nof double occupancy for Correlated Electrons. The constraints are enforced by\nthe pair operator\n$Q(\\vec{x})=\\psi_{\\downarrow}(\\vec{x})\\psi_{\\uparrow}(\\vec{x})$ which\nannihilates the ground state $|\\Psi^0>$. Away from half fillings the operator\n$Q(\\vec{x})$ is replaced by a set of $first$ $class$ Non-Abelian constraints\n$Q^{(-)}_{\\alpha}(\\vec{x})$ restricted to negative energies. The propagator for\na single hole away from half fillings is determined by modified measure which\nis a function of the time duration of the hole propagator. As a result: a) The\nimaginary part of the self energy - is linear in the frequency. At large hole\nconcentrations a Fermi Liquid self energy is obtained. b) For the\nSuperconducting state the constraints generate an asymmetric spectrum\nexcitations between electrons and holes giving rise to an asymmetry tunneling\ndensity of states."
    },
    {
        "anchor": "A THz-Vibration to THz-Radiation Converter Based on Gold Nanoobjects: a\n  Feasibility Study: The estimations done confirm a feasibility of the idea that gold nanobars\n(GNBs) and nanorings (GNRs) irradiated by microwaves could become the terahertz\n(THz) emitters with photon energies within the full width at half maximum of\nlongitudinal acoustic phononic DOS of gold (~13.7-17.5 meV, i.e., 3.3-4.2 THz).\nA scheme of the THz radiation source is suggested based on the domestic\nmicrowave oven irradiating a substrate with multiple deposited GNBs or GNRs.",
        "positive": "Wafer-scale fabrication and room-temperature experiments on\n  graphene-based gates for quantum computation: We have fabricated at wafer scale graphene-based configurations suitable for\nimplementing at room temperature one-qubit quantum gates and a modified\nDeutsch-Jozsa algorithm. Our measurements confirmed the (quasi-)ballistic\nnature of charge carrier propagation through both types of devices, which have\ndimensions smaller than the room-temperature mean-free-path in graphene. As\nsuch, both graphene-based configurations were found to be suitable for quantum\ncomputation. These results are encouraging for demonstrating a miniaturized,\nroom-temperature quantum computer based on graphene."
    },
    {
        "anchor": "Giant spin-orbit splitting in inverted InAs/GaSb double quantum wells: Transport measurements in inverted InAs/GaSb quantum wells reveal a giant\nspin-orbit splitting of the energy bands close to the hybridization gap. The\nsplitting results from the interplay of electron-hole mixing and spin-orbit\ncoupling, and can exceed the hybridization gap. We experimentally investigate\nthe band splitting as a function of top gate voltage for both electron-like and\nhole-like states. Unlike conventional, noninverted two-dimensional electron\ngases, the Fermi energy in InAs/GaSb can cross a single spin-resolved band,\nresulting in full spin-orbit polarization. In the fully polarized regime we\nobserve exotic transport phenomena such as quantum Hall plateaus evolving in\n$e^2/h$ steps and a non-trivial Berry phase.",
        "positive": "Skyrmion Mass from Spin-Phonon Interaction: Inertial mass of a skyrmion arising from spin-phonon interaction is computed\nexactly within a toy model of the magnetoelastic coupling in a ferromagnetic\nfilm. The mass scales as the square of the strength of the magnetoelastic\ncoupling, as the square of the film thickness, and as the first power of the\nlateral size of the skyrmion. For nanometer skyrmions it is in the ballpark of\na few electron masses but may be significantly greater in materials with large\nmagnetostriction. These findings are expected to stand for any complex\nstructure of spin-phonon interaction in real materials. They must be taken into\naccount when addressing the speed of information processing based upon\nskyrmions."
    },
    {
        "anchor": "Bose-Einstein Condensation of Excitons in Bilayer Electron Systems: An ordered state of electrons in solids in which excitons condense was\nproposed many years ago as a theoretical possibility but has, until recently,\nnever been observed. We review recent studies of semiconductor bilayer systems\nthat provide clear evidence for this phenomenon and explain why exciton\ncondensation in the quantum Hall regime, where these experiments were\nperformed, is as likely to occur in electron-electron bilayers as in\nelectron-hole bilayers. In current quantum Hall exciton condensates, disorder\ninduces mobile vortices that flow in response to a supercurrent and limit the\nextremely large bilayer counterflow conductivity.",
        "positive": "Photogalvanic effects in topological insulators: We discuss optical absorption in topological insulators and study possible\nphotoelectric effects theoretically. We found that absorption of circularly\npolarized electromagnetic waves in two-dimensional topological insulators\nresults in electric current in the conducting 1D edge channels, the direction\nof the current being determined by the light polarization. We suggest two ways\nof inducing such a current: due to magnetic dipole electron transitions\nstimulated by irradiation of frequency below the bulk energy gap, and due to\nelectric dipole transitions in the bulk at frequencies larger than the energy\ngap with subsequent capture of the photogenerated carriers on conducting edge\nstates."
    },
    {
        "anchor": "Partial decoherence in mesoscopic systems: The coupling of a mesoscopic system with its environment usually causes total\ndecoherence: at long times the reduced density matrix of the system evolves in\ntime to a limit which is independent of its initial value, losing all the\nquantum information stored in its initial state. Under special circumstances, a\nsubspace of the system's Hilbert space remains coherent, or \"decoherence free\",\nand the reduced density matrix approaches a non-trivial limit which contains\ninformation on its initial quantum state, despite the coupling to the\nenvironment. This situation is called \"partial decoherence\". Here we find the\nconditions for partial decoherence for a mesoscopic system (with $N$ quantum\nstates) which is coupled to an environment. When the Hamiltonian of the system\ncommutes with the total Hamiltonian, one has \"adiabatic decoherence\", which\nyields N-1 time-independent combinations of the reduced density matrix\nelements. In the presence of a magnetic flux, one can measure circulating\ncurrents around loops in the system even at long times, and use them to\nretrieve information on the initial state. For N=2, we demonstrate that partial\ndecoherence can happen only under adiabatic decoherence conditions. However,\nfor $N>2$ we find partial decoherence even when the Hamiltonian of the system\ndoes not commute with the total Hamiltonian, and we obtain the general\nconditions for such non-adiabatic partial decoherence. For an electron moving\non a ring, with $N>2$ single-level quantum dots, non-adiabatic partial\ndecoherence can arise only when the total flux through the ring vanishes (or\nequals an integer number of flux quanta), and therefore there is no asymptotic\ncirculating current.",
        "positive": "Single and multi-particle scattering in Helical liquid with an impurity: We examine the scattering behavior from a single non magnetic impurity in a\nhelical liquid. A helical liquid is a one dimensional system with a pair of\ncounter propagating edge states, which are time reversal partners. In the\nabsence of a magnetic field, time reversal symmetry is conserved and hence\nsingle particle scattering is prohibited. However, multi particle processes are\npossible. We examine the backscattering current and noise, and derive the\neffective scattering charge. A magnetic field enhances the backscattered\ncurrent, but reduces the effective scattering charge. We find that the\nscattering charge can vary between $e$ and $2e$, depending on the strength of\nelectron-electron interactions and the magnetic field."
    },
    {
        "anchor": "Hierarchical nanostructuring approaches for thermoelectric materials\n  with high power factors: The thermoelectric power factor of hierarchically nanostructured materials is\ninvestigated using the nonequilibrium Greens function method for quantum\ntransport, including interactions of electrons with acoustic and optical\nphonons. We describe hierarchical nanostructuring by superlatticelike potential\nbarriers or wells, combined with quantum dot barriers or wells nanoinclusions\nas well as voids in the intermediate region. We show that these structures can\nbe designed in a way that the power factor is not only largely immune to the\npresence of the nanostructure features, but under certain conditions benefits\ncan be achieved as well. Interestingly, we show that these design approaches\nare linked to the energy relaxation of the current flow and whether charge\ncarrier scattering is limited by elastic or inelastic processes. In particular,\nwhen nanostructures form potential barriers, the power factor can be\nsubstantially enhanced under elastic scattering conditions, irrespective of\nnanostructuring density and potential barrier heights. When inelastic\nscattering processes dominate, however, the power factor is inevitably\ndegraded. In the case in which nanostructures form potential wells, despite a\nslight decrease, the power factor is quite resilient under either elastic or\ninelastic scattering processes. These nanostructuring design approaches could\nhelp open the path to the optimization of new generation nanostructured\nthermoelectric materials by not only targeting reductions in thermal\nconductivity, but simultaneous improvements in the power factor as well.",
        "positive": "Anisotropy of Neel \"orange-peel\" coupling in magnetic multilayers: We calculate the energy of the magnetostatic interaction between two\nferromagnetic films with uniform magnetization and correlated interfaces (the\n\"orange-peel\" effect). The \"orange-peel\" coupling is anisotropic: the\ninteraction is ferromagnetic when the films are magnetized in-plane; and it is\nantiferromagnetic when magnetization is out-of-plane. The interaction\nanisotropy can be used to distinguish the \"orange-peel\" effect from the\ninterlayer exchange coupling."
    },
    {
        "anchor": "Imaging coherent transport in graphene (Part II): Probing weak\n  localization: Graphene has opened new avenues of research in quantum transport, with\npotential applications for coherent electronics. Coherent transport depends\nsensitively on scattering from microscopic disorder present in graphene\nsamples: electron waves traveling along different paths interfere, changing the\ntotal conductance. Weak localization is produced by the coherent backscattering\nof waves, while universal conductance fluctuations are created by summing over\nall paths. In this work, we obtain conductance images of weak localization with\na liquid-He-cooled scanning probe microscope, by using the tip to create a\nmovable scatterer in a graphene device. This technique allows us to investigate\ncoherent transport with a probe of size comparable to the electron wavelength.\nImages of magnetoconductance \\textit{vs.} tip position map the effects of\ndisorder by moving a single scatterer, revealing how electron interference is\nmodified by the tip perturbation. The weak localization dip in conductivity at\nB=0 is obtained by averaging magnetoconductance traces at different positions\nof the tip-created scatterer. The width $\\Delta B_{WL}$ of the dip yields an\nestimate of the electron coherence length $L_\\phi$ at fixed charge density.\nThis \"scanning scatterer\" method provides a new way of investigating coherent\ntransport in graphene by directly perturbing the disorder configuration that\ncreates these interferometric effects.",
        "positive": "Field-effect transistors of high-mobility few-layer SnSe$_{2}$: We report the transport properties of mechanically exfoliated few-layer\nSnSe$_{2}$ flakes, whose mobility is found with four probe measurements to be ~\n85 cm$^{2}$V$^{-1}$s$^{-1}$ at 300 K, higher than those of the majority of\nfew-layer transitional metal dichalcogenides (TMDs). The mobility increases\nstrongly with decreased temperature, indicating a phonon limited transport. The\nconductivity of the semiconducting SnSe$_{2}$ shows a metallic behavior, which\nis explained by two competing factors involving the different temperature\ndependence of mobility and carrier density. The Fermi level is found to be 87\nmeV below the conduction band minima (CBM) at 300 K and 12 meV below the CBM at\n78 K, resulting from a heavy n-type doping. Previous studies have found\nSnSe$_{2}$ field-effect transistors (FETs) to be very difficult to turn off. We\nfind the limiting factor to be the flake thickness compared with the maximum\ndepletion width. With fully depleted devices, we are able to achieve a current\non-off ratio of ~10$^{5}$. These results demonstrate the great potential of\nSnSe2 as a two dimensional (2D) semiconducting material and are helpful for our\nunderstanding of other heavily doped 2D materials."
    },
    {
        "anchor": "Subgap tunneling via quantum-interference effect: insulators and charge\n  density waves: A quantum interference effect is discussed for subgap tunneling over a\ndistance comparable to the coherence length, which is a consequence of\n``advanced-advanced'' and ``retarded-retarded'' transmission modes [Altland and\nZirnbauer, Phys. Rev. B 55, 1142 (1997)]. Effects typical of disorder are\nobtained from the interplay between multichannel averaging and higher order\nprocesses in the tunnel amplitudes. Quantum interference effects similar to\nthose occurring in normal tunnel junctions explain magnetoresistance\noscillations of a CDW pierced by nanoholes [Latyshev et al., Phys. Rev. Lett.\n78, 919 (1997)], having periodicity h/2e as a function of the flux enclosed in\nthe nanohole. Subgap tunneling is coupled to the sliding motion by charge\naccumulation in the interrupted chains. The effect is within the same trend as\nrandom matrix theory for normal metal-CDW hybrids [Visscher et al., Phys. Rev.\nB 62, 6873 (2000)]. We suggest that the experiment by Latyshev et al. probes\nweak localization-like properties of evanescent quasiparticles, not an\ninterference effect related to the quantum mechanical ground state.",
        "positive": "Sub-50 mK electronic cooling with large-area superconducting tunnel\n  junctions: In electronic cooling with superconducting tunnel junctions, the cooling\npower is counterbalanced by the interaction with phonons and by the heat flow\nfrom the overheated leads. We study aluminium-based coolers that are equipped\nwith a suspended normal metal and an efficient quasi-particle drain. At\nintermediate temperatures, the phonon bath of the suspended normal metal is\ncooled. At lower temperatures, by adjusting the junction transparency, we\ncontrol the injection current, and thus the superconductor temperature. The\ndevice shows a strong cooling from 150 mK down to about 30 mK, a factor of five\nin temperature. We suggest that spatial non-uniformity in the superconductor\ngap limits the cooling toward lower temperatures."
    },
    {
        "anchor": "A scheme for spin transistor with extremely large on/off current ratio: Quantum wires with periodic local Rashba spin-orbit couplings are proposed\nfor a higher performance of spin field-effect transistor. Fano-Rashba quantum\ninterference due to the spin-dependent modulated structure gives rise to a\nbroad energy range of vanishingly small transmission. Tuning Rashba spin-orbit\ncouplings can provide the on- or off-currents with extremely large on/off\ncurrent ratios even in the presence of a strong disorder.",
        "positive": "Room Temperature Electrically Detected Nuclear Spin Coherence of NV\n  Centers in Diamond: We demonstrate electrical detection of the $^{14}$N nuclear spin coherence of\nNV centers at room temperature. Nuclear spins are candidates for quantum\nmemories in quantum-information devices and quantum sensors, and hence the\nelectrical detection of nuclear spin coherence is essential to develop and\nintegrate such quantum devices. In the present study, we used a pulsed\nelectrically detected electron-nuclear double resonance technique to measure\nthe Rabi oscillations and coherence time ($T_2$) of $^{14}$N nuclear spins in\nNV centers at room temperature. We observed $T_2 \\approx$ 0.9 ms at room\ntemperature. Our results will pave the way for the development of novel\nelectron- and nuclear-spin-based diamond quantum devices."
    },
    {
        "anchor": "Nonlinear Hall effect in Weyl semimetals induced by chiral anomaly: We predict a nonlinear Hall effect in certain Weyl semimetals with broken\ninversion symmetry. When the energy dispersions about pairs of Weyl nodes are\nskewed -- the Weyl cones are \"tilted\" -- the concerted actions of the anomalous\nvelocity and the chiral anomaly give rise to the nonlinear Hall effect. This\nHall conductivity is linear in both electric and magnetic fields, and depends\ncritically on the tilting of the Weyl cones. We also show that this effect does\nnot rely on a finite Berry curvature dipole, in contrast to the intrinsic\nquantum nonlinear Hall effect that was recently observed in type-II Weyl\nsemimetals.",
        "positive": "Colored noise in the fractional Hall effect: duality relations and exact\n  results: We study noise in the problem of tunneling between fractional quantum Hall\nedge states within a four probe geometry. We explore the implications of the\nstrong-weak coupling duality symmetry existent in this problem for relating the\nvarious density-density auto-correlations and cross-correlations between the\nfour terminals. We identify correlations that transform as either ``odd'' or\n``anti-symmetric'', or ``even'' or ``symmetric'' quantities under duality. We\nshow that the low frequency noise is colored, and that the deviations from\nwhite noise are exactly related to the differential conductance. We show\nexplicitly that the relationship between the slope of the low frequency noise\nspectrum and the differential conductance follows from an identity that holds\nto {\\it all} orders in perturbation theory, supporting the results implied by\nthe duality symmetry. This generalizes the results of quantum supression of the\nfinite frequency noise spectrum to Luttinger liquids and fractional statistics\nquasiparticles."
    },
    {
        "anchor": "Influence of random roughness on cantilever curvature sensitivity: In this work we explore the influence of random surface roughness on the\ncantilever sensitivity to respond to curvature changes induced by changes in\nsurface stress. The roughness is characterized by the out-of-plane roughness\namplitude w, the lateral correlation length x, and the roughness or Hurst\nexponent H (0<H<1). The cantilever sensitivity is found to decrease with\nincreasing roughness (decreasing H and/or increasing ratio w/x) or equivalently\nincreasing local surface slope. Finally, analytic expressions of the cantilever\nsensitivity as a function of the parameters w, x, and H are derived in order to\nallow direct implementation in sensing systems.",
        "positive": "Many-body radiative heat pumping: We introduce a local radiative heat-pumping effect between two bodies in a\nmany-body system, obtained by periodically modulating both the temperature and\nthe position of an intermediate object using an external source of energy. We\nshow that the magnitude and the sign of energy flow can be tuned by changing\nthe oscillation amplitude and dephasing of the two parameters. This many-body\neffect paves the way for an efficient and active control of heat fluxes at the\nnanoscale."
    },
    {
        "anchor": "Spin torque and charge resistance of ferromagnetic semiconductor $2\u03c0$\n  and $\u03c0$ domain walls: Charge resistance and spin torque are generated by coherent carrier transport\nthrough ferromagnetic 360 degree domain walls, although they follow\nqualitatively different trends than for 180 degree domain walls. The charge\nresistance of 360 degree domain walls reaches a maximum at an intermediate wall\nthickness, unlike 180 degree domain walls, whose resistance decreases\nmonotonically with wall thickness. The peak amplitude of the spin torque and\nthe optimal thickness of the domain wall to maximize torque for a 360 degree\nwall are more than twice as large as found for a 180 degree domain wall in the\nsame material, producing a larger domain wall velocity for the 360 degree wall\nand suggesting unexpected nonlinearities in magnetoelectronic devices\nincorporating domain wall motion.",
        "positive": "Radiation-induced resistance oscillations in a 2D hole gas: a\n  demonstration of a universal effect: We report on a theoretical insight about the microwave-induced resistance\noscillations and zero resistance states when dealing with p-type semiconductors\nand holes instead of electrons. We consider a high-mobility two-dimensional\nhole gas hosted in a pure Ge/SiGe quantum well. Similarly to electrons we\nobtain radiation-induce resistance oscillations and zero resistance states. We\nanalytically deduce a universal expression for the irradiated\nmagnetoresistance, explaining the origin of the minima positions and their\n$1/4$ cycle phase shift. The outcome is that these phenomena are universal and\nonly depend on radiation and cyclotron frequencies. We also study the\npossibility of having simultaneously two different carriers driven by\nradiation: light and heavy holes. As a result the calculated magnetoresistance\nreveals an interference profile due to the different effective masses of the\ntwo types of carriers."
    },
    {
        "anchor": "Majorana fermions in three dimensions and realization in critical Weyl\n  semimetals: We present two band models for free fermion with charge conjugation symmetry\nin three dimensions. Without time reversal symmetry (TRS), the weak pairing\ngapless $A$-phase is a Majorana fermion $p_x+ip_y$ wave FFLO state while the\nstrong pairing gapped $B$-phase belongs to topologically trivial Class $D$.\nWith TRS, there is a Majorana fermion $B$-phase belonging to Class $DIII$ with\na non-zero Hopf invariant. The TRS $A$-phase is also a Majorana fermion FFLO\nstate with TRS. The surface states of the TRS $B$-phase are either a\nvalley-momentum locked Majorana-Dirac cone or a linear-quadratic mixed cone for\na specific surface. The surface states of the $A$-phase on one surface are\ntopologically nontrivial, either having $\\mathbb{Z}$ or $\\mathbb{Z}_2$\ninvariant depending on whether the system is TRS or not. The edge states of\nthat surface are gapless Majorana modes. The Majorana fermion gapless FFLO\nstates can be realized in critical Weyl semimetals (WSM) in which dual single\nWeyl nodes form dipoles and are nearly annihilated. The gapped $B$-phase\nemerges when Weyl node dipoles are about to be created. The WSM TaAs-family, a\ntype-II WSM series Mo$_x$W$_{1-x}$Te$_2$-family, possible WSM La/LuBi$_{1-x}$\nSb$_x$Te$_3$ and topological crystalline insulators Sn$_{1-x}$Pb$_x$(Te,Se) are\ncandidates to be manipulated into these critical states based on Majorana\nfermion models.",
        "positive": "Spin Manipulation by Giant Valley-Zeeman Spin-Orbit Field in Atom-Thick\n  WSe2: The phenomenon originating from spin-orbit coupling (SOC) provides\nenergy-efficient strategies for spin manipulation and device applications. The\nbroken inversion symmetry interface and resulting electric field induce a\nRashba-type spin-orbit field (SOF), which has been demonstrated to generate\nspin-orbit torque for data storage applications. In this study, we found that\nspin flipping can be achieved by the valley-Zeeman SOF in monolayer WSe2 at\nroom temperature, which manifests as a negative magnetoresistance in the\nvertical spin valve. Quantum transmission calculations based on an effective\nmodel near the K valley of WSe2 confirm the precessional spin transport of\ncarriers under the giant SOF, which is estimated to be 650 T. In particular,\nthe valley-Zeeman SOF-induced spin dynamics was demonstrated to be tunable with\nthe layer number and stacking phase of WSe2 as well as the gate voltage, which\nprovides a novel strategy for spin manipulation and can benefit the development\nof ultralow-power spintronic devices."
    },
    {
        "anchor": "Nitrogen dioxide and ammonia gas molecules interaction studies on\n  phosphorene nanosheet --- a DFT investigation: The adsorption behaviour of hazardous gas molecules, namely nitrogen dioxide\n(NO$_2$) and ammonia (NH$_3$), on phosphorene nanosheet (PNS) was explored by\nmeans of ab initio technique. To improve the structural solidity of pristine\nPNS, we have introduced the passivation of hydrogen and fluorine at the\nterminated edge. The structural solidity of both hydrogen and fluorine\npassivated PNS is verified in terms of formation energy. The main objective of\nthis research work is to probe NO$_2$ and NH$_3$ gases using PNS as a base\nsensing material. The adsorption of various preferential adsorption sites of\nthese gas molecules is studied in accordance with the average HOMO-LUMO gap\nchanges, natural-bond-orbital (NBO) charge transfer, HOMO-LUMO gap, and\nadsorption energy. Notably, the negative value of adsorption energy is found\nupon the adsorption of NO$_2$ and NH$_3$ on PNS and it is in the range of\n$-1.36$ to $-2.45$ eV. The findings of the present research work recommend that\nthe hydrogenated and fluorinated PNS can be effectively used as a chemical\nsensor against NO$_2$ and NH$_3$ molecules.",
        "positive": "First-order spatial coherence of excitons in planar nanostructures: a\n  k-filtering effect: We propose and analyze a k-filtering effect which gives rise to the drastic\ndifference between the actual spatial coherence length of quasi-two-dimensional\n(quasi-2D) excitons or microcavity (MC) polaritons in planar nanostructures and\nthat inferred from far-field optical measurements. The effect originates from\nthe conservation of in-plane wavevector k in the optical decay of the particles\nin outgoing bulk photons. The k-filtering effect explains the large coherence\nlengths recently observed for indirect excitons in coupled quantum wells (QWs),\nbut is less pronounced for MC polaritons at low temperatures, T<10K."
    },
    {
        "anchor": "Modification of band alignment at interface of AlyGa1-ySb/AlxGa1-xAs\n  type-II quantum dots by concentrated sunlight in intermediate band solar\n  cells with separated absorption and depletion regions: We propose a new intermediate band GaAs solar cell comprising an AlxGa1-xAs\nabsorber with built-in GaSb type-II quantum dots (QDs) [a gradual AlxGa1-xAs\nabsorber with built-in AlyGa1-ySb QDs (0<x=y<0.40) as a variant] separated from\nthe depletion region. We study the modification of the band alignment at\ntype-II interface by two-photon absorption of concentrated sunlight. Our\ncalculation shows that photogenerated carriers produce localized exciton-like\nelectron-hole pairs spatially separated at QDs. Local field of such pairs may\nessentially modify potential barrier surrounding QDs, increase recombination\nlifetime of mobile carriers and additional photocurrent generated by twophoton\nabsorption. Concentration of about 300-sun pushes by 15% up the conversion\nefficiency as compared to the efficiency of the reference single junction GaAs\nsolar cell without QDs.",
        "positive": "Prolonging Valley Polarization Lifetime through Gate-Controlled\n  Exciton-to-Trion Conversion in Monolayer Molybdenum Ditelluride: Monolayer 2D semiconductors provide an attractive option for valleytronics\ndue to the valley-addressability by helicity-specific light beam. But the short\nvalley lifetime for excitons have hindered potential valleytronic applications.\nIn this paper, we demonstrate a strategy for prolonging the valley lifetime by\nconverting excitons to trions through effective gate control and by taking\nadvantage of much longer valley lifetime for trions than for excitons. In\ncontinuous-wave experiments, we found the valley polarization increases as gate\nvoltage is tuned away from the charge neutrality, with the degree of valley\npolarization increased from near zero to 38 % for excitons and to 33 % for\ntrions. This is the first successful observation of valley-polarization in\nMoTe2 without a magnetic field. In pump-probe experiments, we found that the\nintervalley scattering process of excitons is significantly suppressed as gate\nvoltage is tuned away from charge neutrality, with scattering time from 0.85 ps\nto ~ 2.17 ps. In contrast, the intervalley scattering rate for trions increases\ndue to increased availability of partner charges for trion spin flipping, with\nscattering time from 1.39 ns down to ~100 ps away from charge neutrality.\nInterestingly, our results show that, despite the accelerated intervalley\nscattering, the trion polarization degree increases due to polarized trion\ngeneration from the exciton-to-trion conversion overtaking the intervalley\ntrion scatterings. Importantly, the efficient exciton-to-trion conversion\nchanged the dominant depolarization mechanisms. As a result, the valley\nlifetime is dramatically improved by 1000 times from excitons to trions at the\ncharge neutrality. Our results shed new light into the depolarization dynamics\nand the interplay of various depolarization channels for excitons and trions\nand provide an effective strategy for prolonging the valley polarization."
    },
    {
        "anchor": "Exciton in phosphorene: Strain, impurity, thickness and heterostructure: Reduced electron screening in two-dimension plays a fundamental role in\ndetermining exciton properties, which dictates optoelectronic and photonic\ndevice performances. Considering the explicit electron-hole interaction within\nthe $GW-$Bethe-Salpeter formalism, we first study the excitonic properties of\npristine phosphorene and investigate the effects of strain and impurity\ncoverage. The calculations reveal strongly bound exciton in these systems with\nanisotropic spatial delocalization. Further, we present a simplified hydrogenic\nmodel with anisotropic exciton mass and effective electron screening as\nparameters, and the corresponding results are in excellent agreement with the\npresent $GW-$BSE calculations. The simplified model is then used to investigate\nexciton renormalization in few-layer and heterostructure phosphorene. The\nchanges in carrier effective mass along with increasing electron screening\nrenormalizes the exciton binding in these systems. We establish that the\npresent model, where the parameters are calculated within computationally less\nexpensive first-principles calculations, can predict exciton properties with\nexcellent accuracy for larger two-dimensional systems, where the many-body\n$GW-$BSE calculations are impossible.",
        "positive": "Contact transparency in mechanically assembled 2D material devices: Two-dimensional atomic crystals (2DACs) can be mechanically assembled with\nprecision for the fabrication of heterostructures, allowing for the combination\nof material building blocks with great flexibility. In addition, while\nconventional nanolithography can be detrimental to most of the 2DACs which are\nnot sufficiently inert, mechanical assembly potentially minimizes the\nnanofabrication processing and preserves the intrinsic physical properties of\nthe 2DACs. In this work we study the interfacial charge transport between\nvarious 2DACs and electrical contacts, by fabricating and characterizing\n2DAC-superconductor junctions through mechanical transfer. Compared to devices\nfabricated with conventional nanolithography, mechanically assembled devices\nshow comparable or better interface transparency. Surface roughness at the\nelectrical contacts is identified to be a major limitation to the interface\nquality."
    },
    {
        "anchor": "Two-color Kerr microscopy of two-dimensional materials with\n  sub-picosecond time resolution: We present a two-color Kerr microscopy system based on two electronically\nsynchronized erbium-fiber laser oscillators with independently tunable emission\nenergies spanning most of the visible spectrum. Combining a spatial resolution\nbelow 2 $\\mu$m and sub-ps time resolution with high sensitivity and cryogenic\nsample temperatures, it is ideally suited for studying spin and valley dynamics\nin a wide range of two-dimensional materials. We illustrate its capabilities by\nstudying a monolayer of the common semiconducting transition metal disulfide\nMoS$_2$.",
        "positive": "Dissipative dynamics of an open quantum battery: Coupling with an external environment inevitably affects the dynamics of a\nquantum system. Here, we consider how charging performances of a quantum\nbattery, modelled as a two level system, are influenced by the presence of an\nOhmic thermal reservoir. The latter is coupled to both longitudinal and\ntransverse spin components of the quantum battery including decoherence and\npure dephasing mechanisms. Charging and discharging dynamics of the quantum\nbattery, subjected to a static driving, are obtained exploiting a proper\nmapping into the so-called spin-boson model. Analytic expressions for the time\nevolution of the energy stored in the weak coupling regime are presented\nrelying on a systematic weak damping expansion. Here, decoherence and pure\ndephasing dissipative coupling are discussed in details. We argue that the\nformer results in better charging performances, showing also interesting\nfeatures reminiscent of the Lamb shift level splitting renormalization induced\nby the presence of the reservoir. Charging stability is also addressed, by\nmonitoring the energy behaviour after the charging protocol has been switched\noff. This study presents a general framework to investigate relaxation effects,\nable to include also non Markovian effects, and it reveals the importance of\ncontrolling and, possibly, engineering system-bath coupling in the realization\nof quantum batteries."
    },
    {
        "anchor": "Electronic transmission in bent quantum wires: Electronic transmission in bent quantum wires modeled by the tight binding\nHamiltonian, and clamped between ideal, semi-infinite leads is studied. The\neffect of `bending' the chain is simulated by introducing a non-zero hopping\nbetween the extremities of the wire. It is seen that the proximity of the two\nends gives rise to Falo line shapes in the transmission spectrum. Transmission\nproperties for both an ordered lattice and a Fibonacci quantum wire are\ndiscussed. In the quasi-periodic Fibonacci chain, the proximity of the two ends\nof the chain closes all the gaps in the spectrum and the spectrum loses it's\nCantor set character.",
        "positive": "Entropy Wave Instability in Dirac and Weyl Semimetals: Hydrodynamic instabilities driven by a direct current are analyzed in 2D and\n3D relativisticlike systems with the Dyakonov-Shur boundary conditions\nsupplemented by a boundary condition for temperature. Besides the conventional\nDyakonov-Shur instability for plasmons, we find an entropy wave instability in\nboth 2D and 3D systems. The entropy wave instability is a manifestation of the\nrelativisticlike nature of electron quasiparticles and a nontrivial role of the\nenergy current in such systems. These two instabilities occur for the opposite\ndirections of fluid flow. While the Dyakonov-Shur instability is characterized\nby the plasma frequency in 3D and the system size in 2D, the frequency of the\nentropy wave instability is tunable by the system size and the flow velocity."
    },
    {
        "anchor": "Observation of Fermi Arc Surface States in a Topological Metal: A New\n  Type of 2D Electron Gas beyond Z2 Topological Insulators: In a topological insulator, it is the electrons on the surface or edge that\ncarry the signature of topology. Recently, a novel topological state has been\nproposed in metals or semimetals (gapless) whose band-structure is similar to\nthat of a three-dimensional analog of graphene. However, to this date the\nsignature of its topology remains an open question. We report the experimental\ndiscovery of a pair of polarized Fermi arc surface state modes in the form of a\nnew type of two-dimensional polarized electron gas on the surfaces of Dirac\nsemimetals. These Fermi arc surface states (FASS) are observed to connect\nacross an even number of bulk band gapless nodes and found to have their spin\nuniquely locked to their momentum. We show that these states are distinctly\ndifferent from the topological surface states (TSS) seen in all known\ntopological insulators. Our observed exotic two-dimensional states not only\nuncover the novel topology of gapless Dirac metals (such as sodium tribismuth\nNa$_3$Bi) but also opens new research frontiers for the utilization of\ntopological Fermi arc electron gases for a wide range of fundamental physics\nand spintronic studies.",
        "positive": "Topological origin of edge states in two-dimensional inversion-symmetric\n  insulators and semimetals: Symmetries play an essential role in identifying and characterizing\ntopological states of matter. Here, we classify topologically two-dimensional\n(2D) insulators and semimetals with vanishing spin-orbit coupling using\ntime-reversal ($\\mathcal{T}$) and inversion ($\\mathcal{I}$) symmetry. This\nallows us to link the presence of edge states in $\\mathcal{I}$ and\n$\\mathcal{T}$ symmetric 2D insulators, which are topologically trivial\naccording to the Altland-Zirnbauer table, to a $\\mathbb{Z}_2$ topological\ninvariant. This invariant is directly related to the quantization of the Zak\nphase. It also predicts the generic presence of edge states in Dirac\nsemimetals, in the absence of chiral symmetry. We then apply our findings to\nbilayer black phosphorus and show the occurrence of a gate-induced topological\nphase transition, where the $\\mathbb{Z}_2$ invariant changes."
    },
    {
        "anchor": "Disorder effects on triple-point fermions: The stability of three-dimensional relativistic semimetals to disorder has\nrecently attracted great attention, but the effect of disorder remains elusive\nfor multifold fermions, that are not present in the framework of quantum field\ntheory. In this paper, we investigate one type of multifold fermions, so-called\ntriple-point fermions (TPFs), which have pseudospin-1 degrees of freedom and\ntopological charges $\\pm2$. Specifically, we consider the effect of disorder on\na minimal, three-band tight-binding model, which realizes the minimal number of\ntwo TPFs. The numerically-obtained, disorder-averaged density of states\nsuggests that, within a finite energy window, the TPFs are robust up to a\ncritical strength of disorder. In the strong disorder regime, the inter-TPF\nscattering is the main mechanism for destroying a single TPF. Moreover, we\nstudy the effects of disorder on the distribution of Fermi arcs and surface\nBerry curvature. We demonstrate that the Fermi arc retains its sharpness at\nweak disorder, but gradually dissolves into the metallic bulk for stronger\ndisorder. In clean limit, the surface Berry curvature exhibits a bipolar\nconfiguration in the surface Brillouin zone. With increasing disorder, the\npositive and negative surface Berry curvature start to merge at the nearby\nmomenta where the Fermi arcs penetrate into bulk.",
        "positive": "Quest for topological superconductivity at superconductor-semiconductor\n  interfaces: We analyze the evidence of Majorana zero modes in nanowires that came from\ntunneling spectroscopy and other experiments, and scout the path to\ntopologically protected states that are of interest for quantum computing. We\nillustrate the importance of the superconductor-semiconductor interface quality\nand sketch out where further progress in materials science of these interfaces\ncan take us. Finally, we discuss the prospects of observing more exotic\nnon-Abelian anyons based on the same materials platform, and how to make\nconnections to high energy physics."
    },
    {
        "anchor": "A vector magnetometer based on a single spin-orbit torque anomalous Hall\n  device: In many applications, the ability to measure the vector information of a\nmagnetic field with high spatial resolution and low cost is essential, but it\nis still a challenge for existing magnetometers composed of multiple sensors.\nHere, we report a single-device based vector magnetometer, which is enabled by\nspin-orbit torque, capable of measuring a vector magnetic field using the\nharmonic Hall resistances of a superparamagnetic ferromagnet (FM)/heavy metal\n(HM) bilayer. Under an ac driving current, the first and second harmonic Hall\nresistances of the FM/HM bilayer show a linear relationship with the vertical\nand longitudinal component (along the current direction) of the magnetic field,\nrespectively. By employing a L-shaped Hall device with two orthogonal arms, we\ncan measure all the three field components simultaneously, so as to detect both\nthe amplitude and direction of magnetic field in a three-dimensional space. As\nproof of concepts, we demonstrate both angular position sensing on the three\ncoordinate planes and vector mapping of magnetic field generated by a permanent\nmagnet, both of which are in good agreement with the simulation results.\nCrosstalk between vertical and longitudinal field components at large field is\ndiscussed using theoretical models.",
        "positive": "Statistics of Impedance and Scattering Matrices in Chaotic Microwave\n  Cavities: Single Channel Case: We discuss a model for studying the statistical properties of the impedance\n($Z$) and scattering ($S$) matrices of open electromagnetic cavities with\nseveral transmission lines or waveguides connected to the cavity. In this\npaper, we mainly discuss the single port case. The generalization to multiple\nports is treated in a companion paper. The model is based on assumed properties\nof chaotic eigenfunctions for the closed system. Analysis of the model\nsuccessfully reproduces features of the random matrix model believed to be\nuniversal, while at the same time incorporating features which are specific to\nindividual systems. Statistical properties of the cavity impedance $Z$ are\nobtained in terms of the radiation impedance (i.e., the impedance seen at a\nport with the cavity walls moved to infinity). Effects of wall absorption are\ndiscussed. Theoretical predictions are tested by direct comparison with\nnumerical solutions for a specific system. (Here the word universal is used to\ndenote high frequency statistical properties that are shared by the members of\nthe general class of systems whose corresponding ray trajectories are chaotic.\nThese universal properties are, by definition, independent of system-specific\ndetails.)"
    },
    {
        "anchor": "Pure spin current devices based on ferromagnetic topological insulators: Two-dimensional topological insulators possess two counter propagating edge\nchannels with op- posite spin direction. Recent experimental progress allowed\nto create ferromagnetic topological insulators realizing a quantum anomalous\nHall (QAH) state. In the QAH state one of the two edge channels disappears due\nto the strong ferromagnetic exchange field. We investigate heterostuctures of\ntopological insulators and ferromagnetic topological insulators by means of\nnumerical transport calculations. We show that spin current flow in such\nheterostructures can be controlled with high fidelity. Specifically, we propose\nspintronic devices that are capable of creating, switching and de- tecting pure\nspin currents using the same technology. In these devices electrical currents\nare directly converted into spin currents, allowing a high conversion\nefficiency. Energy independent transport properties in combination with large\nbulk gaps in some topological insulator materials may allow operation even at\nroom temperature.",
        "positive": "Spin transition in the fractional quantum Hall regime: Effect of extent\n  of the wave function: Using a magnetocapacitance technique, we determine the magnetic field of the\nspin transition, B*, at filling factor nu=2/3 in the 2D electron system in\nGaAs/AlGaAs heterojunctions. The field B* is found to decrease appreciably as\nthe wave function extent controlled by back gate voltage is increased. Our\ncalculations show that the contributions to the shift of B* from the change of\nthe Coulomb energy and the g factor change due to nonparabolicity are\napproximately the same. The observed relative shift of B* is described with no\nfitting parameters."
    },
    {
        "anchor": "Structural dynamics probed by high-coherence electron pulses: Ultrafast measurement technology provides essential contributions to our\nmicroscopic understanding of the properties and functions of solids and\nnanostructures. Atomic-scale vistas with ever-growing spatial and temporal\nresolution are offered by methods based on short pulses of x-rays and\nelectrons. Time-resolved electron diffraction and microscopy are among the most\npowerful approaches to investigate non-equilibrium structural dynamics in\nexcited matter. In this article, we discuss recent advances in ultrafast\nelectron imaging enabled by significant improvements in the coherence of pulsed\nelectron beams. Specifically, we review the development and first application\nof Ultrafast Low-Energy Electron Diffraction (ULEED) for the study of\nstructural dynamics at surfaces, and discuss novel opportunities of Ultrafast\nTransmission Electron Microscopy (UTEM) facilitated by laser-triggered field\nemission sources. These and further developments will render coherent electron\nbeams an essential component in the future of ultrafast nanoscale imaging.",
        "positive": "Low friction and rotational dynamics of crystalline flakes in solid\n  lubrication: Solids at incommensurate contact display low-friction, 'superlubric',\nsliding. For graphene flakes on a graphite surface, superlubric sliding is only\ntemporary due to rotation of the flakes from incommensurate to commensurate\ncontact with the substrate. We examine this rotational channel of friction in a\nprototype geometry of meso- and macroscopic solid lubrication. By molecular\ndynamics simulations and theoretical arguments we find that two surfaces\nlubricated by mobile, rotating graphene flakes exhibit stable superlubric\nsliding as for ideally incommensurate contacts also when they are covered by\nrandomly oriented pinned graphene patches. For commensurate surfaces, we find a\nlow friction state at low temperature where incommensurate states are not\ndestroyed by thermal fluctuations."
    },
    {
        "anchor": "Practical use of waveguides for polarized neutrons studies: We present the use of planar waveguides to produce neutron microbeams in\norder to investigate magnetic micro-structures with a micrometric spatial\nresolution. We report experimental results on such measurements on a polarized\nneutron reflectometer using a nonmagnetic waveguide structure to probe an\namorphous magnetic microwire. The spin-resolved transmission of a neutron\nmicrobeam through a microwire was studied. The one dimensional mapping of the\nneutron precession across the wire was measured.",
        "positive": "Hanle Magnetoresistance in Thin Metal Films with Strong Spin-Orbit\n  Coupling: We report measurements of a new type of magnetoresistance in Pt and Ta thin\nfilms. The spin accumulation created at the surfaces of the film by the spin\nHall effect decreases in a magnetic field because of the Hanle effect,\nresulting in an increase of the electrical resistance as predicted by Dyakonov\n[PRL 99, 126601 (2007)]. The angular dependence of this magnetoresistance\nresembles the recently discovered spin Hall magnetoresistance in Pt/Y3Fe5O12\nbilayers, although the presence of a ferromagnetic insulator is not required.\nWe show that this Hanle magnetoresistance is an alternative, simple way to\nquantitatively study the coupling between charge and spin currents in metals\nwith strong spin-orbit coupling."
    },
    {
        "anchor": "Fluctuation of Conductance Peak Spacings in Large Semiconductor Quantum\n  Dots: Fluctuation of Coulomb blockade peak spacings in large two-dimensional\nsemiconductor quantum dots are studied within a model based on the\nelectrostatics of several electron islands among which there are random\ninductive and capacitive couplings. Each island can accommodate electrons on\nquantum orbitals whose energies depend also on an external magnetic field. In\ncontrast with a single island quantum dot, where the spacing distribution is\nclose to Gaussian, here the distribution has a peak at small spacing value. The\nfluctuations are mainly due to charging effects. The model can explain the\noccasional occurrence of couples or even triples of closely spaced Coulomb\nblockade peaks, as well as the qualitative behavior of peak positions with the\napplied magnetic field.",
        "positive": "Adiabatic amplification of plasmons and demons in 2D systems: We theoretically investigate charged collective modes in a two-dimensional\nconductor with hot electrons where the instantaneous mode frequencies gradually\nincrease or decrease with time. We show that the loss compensation or even\namplification of the modes may occur. We apply our theory to two types of\ncollective modes in graphene, the plasmons and the energy waves, which can be\nprobed in optical pump-probe experiments."
    },
    {
        "anchor": "Cohesion and conductance of disordered metallic point contacts: The cohesion and conductance of a point contact in a two-dimensional metallic\nnanowire are investigated in an independent-electron model with hard-wall\nboundary conditions. All properties of the nanowire are related to the Green's\nfunction of the electronic scattering problem, which is solved exactly via a\nmodified recursive Green's function algorithm. Our results confirm the validity\nof a previous approach based on the WKB approximation for a long constriction,\nbut find an enhancement of cohesion for shorter constrictions. Surprisingly,\nthe cohesion persists even after the last conductance channel has been closed.\nFor disordered nanowires, a statistical analysis yields well-defined peaks in\nthe conductance histograms even when individual conductance traces do not show\nwell-defined plateaus. The shifts of the peaks below integer multiples of\n$2e^2/h$, as well as the peak heights and widths, are found to be in excellent\nagreement with predictions based on random matrix theory, and are similar to\nthose observed experimentally. Thus abrupt changes in the wire geometry are not\nnecessary for reproducing the observed conductance histograms. The effect of\ndisorder on cohesion is found to be quite strong and very sensitive to the\nparticular configuration of impurities at the center of the constriction.",
        "positive": "Low-frequency Raman signature of Ag-intercalated few-layer MoS$_2$: Density functional theory based calculations and experimental analysis on a\nlimited number of real samples are performed to study how the presence of\nsilver intercalated in the van der Waals gap of few-layer MoS$_2$ affects the\nlow-frequency Raman active modes of this material. Silver is found to\npredominantly affect the breathing-like and shear-like vibrational modes of\nMoS$_2$. These modes correspond to quasi-rigid movements of each individual\nlayer with a restoring force (and, in turn, frequency) that is determined by\nmodulations in the weak interlayer interactions. Noticeable red-shifts with\nincreasing Ag concentration are found for all low-frequency modes. This finding\nindicates the potential for low-frequency vibrations as useful gauges for\npractical determination of silver concentration using low-frequency Raman\nspectroscopy. This work also describes a semi-classical linear chain model that\nallows to extrapolate results to a large number of layers. Further,\nfirst-principles calculations show how Raman spectroscopy can be used to\ncharacterize the quality of the two-dimensional interface between MoS$_2$ and a\nsilver substrate."
    },
    {
        "anchor": "Plane polarized-longitudinal Phonons in realistic low dimensional\n  systems: A realistic one-dimensional system has not only longitudinal phonons, but\nalso possible transverse modes, which derive their restoring force from\nlongitudinal interaction. We show that transverse motion results in a quartic\ndisplacement term in transverse direction as the first non-vanishing term in\nthe potential energy. This results in solution of a composite longitudinal\nmotion superimposed by a transverse motion propagating along the length\ndirection identified as a plane polarized phonons. Interestingly, solutions of\nthe quartic nonlinear equation have been expressed accurately, though\napproximately in terms of sinusoidal solutions by modifying the periodicity of\nsin function. The phonons along the transverse direction, now with a weakened\nfrequency compared to the longitudinal has interesting impact- it gives rise to\nnegative Gruneisen parameter with a value of -1 and is responsible for negative\nthermal expansion in the low temperature regime. Similar results of graphene\nsheet based on consideration of transverse (surface ripple like) modes to the\nplanar direction, provides explanation to the observed negative thermal\nexpansion in low temperature regime. The concept of plane polarized phonons\nseems new and interesting. All dynamics of atomic motion, despite involving\nquartc nonlinear equation is expressible in terms of simple harmonic motion.\nThe most important feature of the transverse modes of an open surface or chain\nis their dependence on lateral or longitudinal modes, and as soon as more\nchains or more surfaces are added, bulk interactions are initiated and\nlongitudinal dependence of transverse motion is lost and so also very\ndistinguishing thermodynamic properties.",
        "positive": "Room-temperature Tunable Fano Resonance by Chemical Doping in Few-layer\n  Graphene Synthesized by Chemical Vapor Deposition: A Fano-like phonon resonance is observed in few-layer (~3) graphene at room\ntemperature using infrared Fourier transform spectroscopy. This Fano resonance\nis the manifestation of a strong electron-phonon interaction between the\ndiscrete in-plane lattice vibrational mode and continuum electronic excitations\nin graphene. By employing ammonia chemical doping, we have obtained different\nFano line shapes ranging from anti-resonance in hole-doped graphene to\nphonon-dominated in n-type graphene. The Fano resonance shows the strongest\ninterference feature when the Fermi level is located near the Dirac point. The\ncharged phonon exhibits much-enhanced oscillator strength and experiences a\ncontinuous red shift in frequency as electron density increases. It is\nsuggested that the phonon couples to different electronic transitions as Fermi\nlevel is tuned by chemical doping."
    },
    {
        "anchor": "Assembling topological insulators with lasers: Despite the realizations of spin-orbit (SO) coupling and synthetic gauge\nfields in optical lattices, the associated time-reversal symmetry breaking, and\n1D nature of the observed SO coupling pose challenges to obtain intrinsic $Z_2$\ntopological insulator. We propose here a model optical device for engineering\nintrinsic $Z_2$ topological insulator which can be easily set up with the\nexisting tools. The device is made of a periodic lattice of quantum\nmechanically connected atomic wires (dubbed SO wires) in which the laser\ngenerated SO coupling ($\\alpha_{\\bf k}$, with ${\\bf k}$ being the momentum) is\nreversed in every alternating wires as $\\pm\\alpha_{\\bf k}$. The associated\nsmall Zeeman terms are also automatically reversed in any two adjacent SO\nwires, which allow to effectively restore the global time-reversal (TR)\nsymmetry. Therefore, the two SO wires serve as the TR partner to each other\nwhich is an important ingredient for $Z_2$ topological insulators according to\nthe Kane-Mele model. These properties ensure a non-trivial $Z_2$ invariant\ntopological insulator phase with protected edge states. We also discuss that a\nnon-local current measurement can be used to detect the chiral edge states.",
        "positive": "Photon shot noise: A recent theory is reviewed for the shot noise of coherent radiation\npropagating through a random medium. The Fano factor P/I (the ratio of the\nnoise power and the mean transmitted current) is related to the scattering\nmatrix of the medium. This is the optical analogue of Buttiker's formula for\nelectronic shot noise. Scattering by itself has no effect on the Fano factor,\nwhich remains equal to 1 (as for a Poisson process). Absorption and\namplification both increase the Fano factor above the Poisson value. For strong\nabsorption P/I has the universal limit 1+3f/2 with f the Bose-Einstein function\nat the frequency of the incident radiation. This is the optical analogue of the\none-third reduction factor of electronic shot noise in diffusive conductors. In\nthe amplifying case the Fano factor diverges at the laser threshold, while the\nsignal-to-noise ratio I^2/P reaches a finite, universal limit."
    },
    {
        "anchor": "Electron localization and entanglement in a two-electron quantum dot: Calculations for two electrons in an elliptic quantum dot, using symmetry\nbreaking at the unrestricted Hartree-Fock level and subsequent restoration of\nthe broken parity via projection techniques, show that the electrons can\nlocalize and form a molecular dimer, described by a Heitler-London-type wave\nfunction. The calculated singlet-triplet splitting (J) as a function of the\nmagnetic field (B) agrees with cotunneling measurements. Knowledge of the dot\nshape and of J(B) allows determination of the degree of entanglement in the\nground state of the dot, which is of interest for the implementation of quantum\nlogic gates. The theoretical value agrees with the experimental estimates.",
        "positive": "Quantum suppression of shot noise in field emitters: We have analyzed the shot noise of electron emission under strong applied\nelectric fields within the Landauer-Buttiker scheme. In contrast to the\nprevious studies of vacuum-tube emitters, we show that in new generation\nelectron emitters, scaled down to the nanometer dimensions, shot noise much\nsmaller than the Schottky noise is observable. Carbon nanotube field emitters\nare among possible candidates to observe the effect of shot-noise suppression\ncaused by quantum partitioning."
    },
    {
        "anchor": "Spin liquid mediated RKKY interaction: We propose an RKKY-type interaction that is mediated by a spin liquid. If a\nspin liquid ground state exists such an interaction could leave a fingerprint\nby ordering underlying localized moments such as nuclear spins. This\ninteraction has a unique phenomenology that is distinct from the RKKY\ninteraction found in fermionic systems; most notably the lack of a Fermi\nsurface and absence of the requirement for itinerant electrons, since most spin\nliquids are insulators. As a working example we investigate the two-dimensional\nspin-1/2 kagome antiferromagnet (KAFM), although the treatment remains general\nand can be extended to other spin liquids and dimensions. We find that several\ndifferent nuclear spin orderings minimize the RKKY-type energy induced by the\nKAFM but are unstable due to a zero-energy flat magnon band. Despite this we\nshow that a small magnetic field is able to gap out this magnon spectrum for\nsome of the orderings resulting in an intricate nuclear magnetism.",
        "positive": "Phase transitions in intrinsic magnetic topological insulator with\n  high-frequency pumping: In this work, we investigate the topological phase transitions in an\neffective model for a topological thin film with high-frequency pumping. In\nparticular, our results show that the circularly polarized light can break the\ntime-reversal symmetry and induce the quantum anomalous Hall insulator (QAHI)\nphase. Meanwhile, the bulk magnetic moment can also break the time-reversal\nsymmetry. Therefore, it shows rich phase diagram by tunning the intensity of\nthe light and the thickness of the thin film. Using the parameters fitted by\nexperimental data, we give the topological phase diagram of the Cr-doped\nBi$_{2}$Se$_{3}$ thin film, showing that by modulating the strength of the\npolarized optical field in an experimentally accessible range, there are four\ndifferent phases: the normal insulator phase, the time-reversal-symmetry-broken\nquantum spin Hall insulator phase, and two different QAHI phases with opposite\nChern numbers. Comparing with the non-doped Bi$_{2}$Se$_{3}$, it is found that\nthe interplay between the light and bulk magnetic moment separates the two\ndifferent QAHI phases with opposite Chern numbers. The results show that an\nintrinsic magnetic topological insulator with high-frequency pumping is an\nideal platform for further exploring various topological phenomena with a\nspontaneously broken time-reversal symmetry."
    },
    {
        "anchor": "Band folding, strain, confinement, and surface relaxation effects on the\n  electronic structure of GaAs and GaP: from bulk to nanowires: In this paper we show how to link the electronic structures of two III-V\nsystems, one a direct gap material, GaAs, and the other an indirect gap\nmaterial, GaP, from their bulks right down to the shape of thin nanowires. GaAs\nand GaP bulk and nanowire systems are studied in the zincblende and wurtzite\nstructures both free of strain and subjected to biaxial strains perpendicular\nto the [111]/[0001] direction. We provide an interpretation of the band\nstructure of nanowires, grown along the [111] (zinc-blende structure) and the\n[0001] (wurtzite structure) directions, in terms of the bulk band structures of\nthe corresponding binary compounds. The procedure reveals the origin of the\nvalence and conduction valleys relevant to determine the nature (direct or\nindirect) of the band gaps and the kind (direct and pseudodirect) of the\nvalence to conduction transitions. Thus, by calculating only the bulk bands it\nis possible to describe the behavior of the nanowire bands even for very thin\nnanowires. The effects on the band structures due to biaxial strain are\nanalogously analyzed, providing for bulk GaP the first results in literature.\nThe role of confinement, and surface relaxation, in determining the nanowire\nelectronic structure of thin nanowires are analyzed separately revealing that\nthe change in the nature of the band gap is due mainly to surface relaxation\neffects, not confinement. We show that the change for indirect/direct of the\ngap from the bulk to the 1D systems is mainly due to the competition between\nthe energies of bulk conduction valleys which are differently inuenced by\nconfinement and strain. While the main effect of confinement is to open all\ngaps it is not necessarily the main cause of the direct/indirect change in the\nnature of the electronic gap as instead is usually claimed in the literature.",
        "positive": "Thermal bistability through coupled photonic resonances: We present a scheme for achieving thermal bistability based on the selective\ncoupling of three optical resonances. This approach requires one of the\nresonant frequencies to be temperature dependent, which can occur in materials\nexhibiting strong thermo-optic effects. For illustration, we explore thermal\nbistability in two different passive systems, involving either a periodic array\nof Si ring resonators or parallel GaAs thin films separated by vacuum and\nexchanging heat in the near field. Such a scheme could prove useful for thermal\nmemory devices operating with transition times $\\lesssim$ hundreds of\nmilliseconds."
    },
    {
        "anchor": "Topological superconductivity in nanowires proximate to a diffusive\n  superconductor-magnetic insulator bilayer: We study semiconductor nanowires coupled to a bilayer of a disordered\nsuperconductor and a magnetic insulator, motivated by recent experiments\nreporting possible Majorana-zero-mode signatures in related architectures.\nSpecifically, we pursue a quasiclassical Usadel equation approach that treats\nsuperconductivity in the bilayer self-consistently in the presence of\nspin-orbit scattering, magnetic-impurity scattering, and Zeeman splitting\ninduced by both the magnetic insulator and a supplemental applied field. Within\nthis framework we explore prospects for engineering topological\nsuperconductivity in a nanowire proximate to the bilayer. We find that a\nmagnetic-insulator-induced Zeeman splitting, mediated through the\nsuperconductor alone, cannot induce a topological phase since the destruction\nof superconductivity (i.e., Clogston limit) preempts the required regime in\nwhich the nanowire's Zeeman energy exceeds the induced pairing strength.\nHowever, this Zeeman splitting does reduce the critical applied field needed to\naccess the topological phase transition, with fields antiparallel to the\nmagnetization of the magnetic insulator having an optimal effect. Finally, we\nshow that magnetic-impurity scattering degrades the topological phase, and\nspin-orbit scattering, if present in the superconductor, pushes the Clogston\nlimit to higher fields yet simultaneously increases the critical applied field\nstrength.",
        "positive": "Nonequilibrium Green's Function simulation of Cu2O photocathodes for\n  photoelectrochemical hydrogen production: In this work we present a simulation of the semiconductor electrodes of\nphotoelectrochemical (PEC) water splitting cells based on the nonequilibrium\nGreen's function (NEGF) formalism. While the performance of simple PEC cells\ncan be adequately explained with semi-classical drift-diffusion theory, the\nincreasing interest towards thin film cells and nanostructures in general\nrequires theoretical treatment that can capture the quantum phenomena\ninfluencing the charge carrier dynamics in these devices. Specifically, we\nstudy a p-type Cu2O electrode and examine the influence of the bias voltage,\nreaction kinetics and the thickness of the Cu2O layer on the generated\nphotocurrent. The NEGF equations are solved in a self-consistent manner with\nthe electrostatic potential from Poisson's equation, sunlight induced photon\nscattering and the chemical overpotential required to drive the water splitting\nreaction. We show that the NEGF simulation accurately reproduces experimental\nresults from both voltammetry and impedance spectroscopy measurements, while\nproviding an energy resolved solution of the charge carrier densities and\ncorresponding currents inside the semiconductor electrode at nanoscale."
    },
    {
        "anchor": "Voltage controlled spin precession: A recent experiment reports a non-local spin-signal that shows oscillatory\nbehavior as a function of gate voltage when the contacts are magnetized along\nthe direction of current flow, but not when they are magnetized perpendicular\nto the current, in agreement with the predictions from a simple theory. In this\npaper we first present a straightforward extension of this theory to include\nthe angular spectrum of electrons and the extended injecting and detecting\ncontacts. The results are in good agreement with those from a non-equilibrium\nGreen function (NEGF)- based model with contact parameters adjusted to fit the\nexperimental contact conductances. They also describe certain aspects of the\nexperiment fairly well, but other aspects deserve further investigation.",
        "positive": "Topological Band Theory for Non-Hermitian Hamiltonians: We develop the topological band theory for systems described by non-Hermitian\nHamiltonians, whose energy spectra are generally complex. After generalizing\nthe notion of gapped band structures to the non-Hermitian case, we classify\n\"gapped\" bands in one and two dimensions by explicitly finding their\ntopological invariants. We find nontrivial generalizations of the Chern number\nin two dimensions, and a new classification in one dimension, whose topology is\ndetermined by the energy dispersion rather than the energy eigenstates. We then\nstudy the bulk-edge correspondence and the topological phase transition in two\ndimensions. Different from the Hermitian case, the transition generically\ninvolves an extended intermediate phase with complex-energy band degeneracies\nat isolated \"exceptional points\" in momentum space. We also systematically\nclassify all types of band degeneracies."
    },
    {
        "anchor": "Transport Spectroscopy of a Kondo quantum dot coupled to a finite size\n  grain: We analyse a simple setup in which a quantum dot is strongly connected to a\nmetallic grain or finite size wire and weakly connected to two normal leads.\nThe Kondo screening cloud essentially develops in the strongly coupled grain\nwhereas the two weakly connected reservoirs can be used as transport probes.\nSince the transport channels and the screening channels are almost decoupled,\nsuch a setup allows an easier access to the measure of finite-size Kondo\neffects.",
        "positive": "Complete tunneling of acoustic waves between closely spaced\n  piezoelectric crystals: When two piezoelectric solids are placed in close proximity, acoustic waves\n(phonons) can \"tunnel\" across a vacuum gap transmitting energy between the two\nsolids. Here, we demonstrate analytically that not only is such a phenomenon\npossible, but that a simple resonance condition exists for which complete\ntransmission of the incoming wave is possible, physically corresponding to the\nexcitation of leaky surface waves. This result is derived for an arbitrary\nanisotropic crystal symmetry and orientation. We also show that the complete\ntransmission condition can be related to the surface electric impedance and the\neffective surface permittivity of the piezoelectric material, making it\npossible to be determined experimentally. In addition, we present numerical\nresults for the maximum power transmittance of a slow transverse wave,\ntunneling between identical ZnO crystals, as function of all possible crystal\norientations. The results show a large range of orientations for which complete\ntunneling can be achieved."
    },
    {
        "anchor": "Current-induced cooling phenomenon in a two-dimensional electron gas\n  under a magnetic field: We investigate the spatial distribution of temperature induced by a dc\ncurrent in a two-dimensional electron gas (2DEG) subjected to a perpendicular\nmagnetic field. We numerically calculate the distributions of the electrostatic\npotential phi and the temperature T in a 2DEG enclosed in a square area\nsurrounded by insulated-adiabatic (top and bottom) and isopotential-isothermal\n(left and right) boundaries (with phi_{left} < phi_{right} and T_{left}\n=T_{right}), using a pair of nonlinear Poisson equations (for phi and T) that\nfully take into account thermoelectric and thermomagnetic phenomena, including\nthe Hall, Nernst, Ettingshausen, and Righi-Leduc effects. We find that, in the\nvicinity of the left-bottom corner, the temperature becomes lower than the\nfixed boundary temperature, contrary to the naive expectation that the\ntemperature is raised by the prevalent Joule heating effect. The cooling is\nattributed to the Ettingshausen effect at the bottom adiabatic boundary, which\npumps up the heat away from the bottom boundary. In order to keep the adiabatic\ncondition, downward temperature gradient, hence the cooled area, is developed\nnear the boundary, with the resulting thermal diffusion compensating the upward\nheat current due to the Ettingshausen effect.",
        "positive": "Propagating edge states in strained honeycomb lattices: We investigate the helically-propagating edge states associated with\npseudo-Landau levels in strained honeycomb lattices. We exploit chiral symmetry\nto derive a general criterion for the existence of these propagating edge\nstates in the presence of only nearest-neighbour hoppings and we verify our\ncriterion using numerical simulations of both uni-axially and trigonally\nstrained honeycomb lattices. We show that the propagation of the helical edge\nstate can be controlled by engineering the shape of the edges. Sensitivity to\nchiral-symmetry-breaking next-nearest-neighbour hoppings is assessed. Our\nresult opens up an avenue toward the precise control of edge modes through\nmanipulation of the edge shape."
    },
    {
        "anchor": "Superconducting platinum silicide for electron cooling in silicon: We demonstrate electron cooling in silicon using platinum silicide as a\nsuperconductor contact to selectively remove the highest energy electrons. The\nsuperconducting critical temperature of bulk PtSi is reduced from around 1 K to\n0.79 K using a thin film (10 nm) of PtSi, which enhances cooling performance at\nlower temperatures and enables electron cooling to be demonstrated from 100 mK\nto 50 mK.",
        "positive": "Lateral heterojunctions within monolayer semiconductors: Heterojunctions between three-dimensional (3D) semiconductors with different\nbandgaps are the basis of modern light-emitting diodes, diode lasers, and\nhigh-speed transistors. Creating analogous heterojunctions between different\ntwo-dimensional (2D) semiconductors would enable band engineering within the 2D\nplane and open up new realms in materials science, device physics and\nengineering. Here we demonstrate that seamless high-quality in-plane\nheterojunctions can be grown between the 2D monolayer semiconductors MoSe2 and\nWSe2. The junctions, grown by lateral hetero-epitaxy using physical vapor\ntransport, are visible in an optical microscope and show enhanced\nphotoluminescence. Atomically resolved transmission electron microscopy reveals\nthat their structure is an undistorted honeycomb lattice in which substitution\nof one transition metal by another occurs across the interface. The growth of\nsuch lateral junctions will allow new device functionalities, such as in-plane\ntransistors and diodes, to be integrated within a single atomically thin layer."
    },
    {
        "anchor": "Orbital angular momentum driven intrinsic spin Hall effect: We propose a mechanism of intrinsic spin Hall effect (SHE). In this\nmechanism, local orbital angular momentum (OAM) induces electron position shift\nand couples with the bias electric field to generate orbital Hall effect (OHE).\nSHE then emerges as a concomitant effect of OHE through the atomic spin-orbit\ncoupling. Spin Hall conductivity due to this mechanism is estimated to be\ncomparable to experimental values for heavy metals. This mechanism predicts the\nsign change of the spin Hall conductivity as the spin-orbit polarization\nchanges its sign, and also correlation between the spin Hall conductivity and\nthe splitting of the Rashba-type spin splitting at surfaces.",
        "positive": "Electrically and Magnetically Resonant dc SQUID Metamaterials: We propose a superconducting metamaterial design consisting of meta-atoms\n(MAs) which are each composed of a direct current (dc) superconducting quantum\ninterference device (SQUID) and a superconducting rod. This design provides\nnegative refraction index behavior for a wide range of structure parameters."
    },
    {
        "anchor": "Lasing and transport in a quantum dot-resonator circuit: We study a double quantum dot system coherently coupled to an electromagnetic\nresonator. A current through the dot system can create a population inversion\nin the dot levels and, within a narrow resonance window, a lasing state in the\nresonator. The lasing state correlates with the transport properties. On one\nhand, this allows probing the lasing state via a current measurement. On the\nother hand, the resulting narrow current peak allows resolving small\ndifferences in the dot properties, e.g., a small difference in the Zeeman\nsplittings of the two dots. For realistic situations relaxation processes have\npronounced consequences. Remarkably, they may even enhance the resolution\nbetween different spin states by releasing a trapped population in the\noff-resonant spin channel.",
        "positive": "Enhancement of Rashba spin-orbit coupling by electron-electron\n  interaction: We studied how the electron-electron (e-e) interaction enhances the strength\nof the Rashba spin-orbit coupling (RSOC) and opens the possibility of\ngenerating a spin-polarized output current from an unpolarized electric current\nwithout any magnetic elements. In this regard, we proposed a novel design of a\ngraphene-like junction based on the $e$-$e$ interaction and the $RSOC$. The\nresults showed that the $e$-$e$ interaction with $RSOC$ opens a spin energy gap\nand extremely enhances the $RSOC$ in this spin energy gap. Interestingly, the\njunction produces a large spin-polarized current and could act as a\nhigh-efficiency spin filter device (nearly 100\\% spin polarization) at room\ntemperature even at low Rashba and e-e interaction strengths. However, with an\nappropriate design, we showed that RSOC could strongly weaken the\nspin-polarized current and the spin energy gap, which is solely produced by the\n$e$-$e$ interaction, but a high spin polarization persists in some energy\nranges."
    },
    {
        "anchor": "Gate-induced interlayer asymmetry in ABA-stacked trilayer graphene: We calculate the electronic band structure of ABA-stacked trilayer graphene\nin the presence of external gates, using a self-consistent Hartree\napproximation to take account of screening. In the absence of a gate potential,\nthere are separate pairs of linear and parabolic bands at low energy. A gate\nfield perpendicular to the layers breaks mirror reflection symmetry with\nrespect to the central layer and hybridizes the linear and parabolic low-energy\nbands, leaving a chiral Hamiltonian essentially different from that of\nmonolayer or bilayer graphene. Using the self-consistent Born approximation, we\nfind that the density of states and the minimal conductivity in the presence of\ndisorder generally increase as the gate field increases, in sharp contrast with\nbilayer graphene.",
        "positive": "Cross Feshbach resonance: Feshbach resonance occurs when a pair of free particles is resonantly coupled\nto a molecular bound state. In the field of ultracold quantum gases, atomic\nFeshbach resonances became a usual tool for tailoring atomic interactions\nopening up many new applications in this field. In a semiconductor microcavity,\nthe Feshbach resonance appears when two lower polaritons are coupled to the\nmolecular biexciton state. Here, we demonstrate the existence of a cross\nFeshbach resonance for which a pair of polaritons, lower together with upper,\neffectively couples to the biexciton state. This demonstration is a crucial\nstep towards the efficient generation of entangled photon pairs in a\nsemiconductor microcavity. The existence of a Cross Feshbach resonance\nestablishes the condition to convert a pair of upper and lower polaritons via\nthe biexciton state into two lower polaritons, paving the way for the\ngeneration of momentum and polarization entangled photons."
    },
    {
        "anchor": "Artificial kagome spin ice magnetic phase recognition from the initial\n  magnetization curve: Artificial spin ices (ASIs) are designable arrays of interacting nanomagnets\nthat span a wide range of magnetic phases associated with a number of spin\nlattice models. Here, we demonstrate that the phase of an artificial kagome\nspin ice can be determined from its initial magnetization curve. As a proof of\nconcept, micromagnetic simulations of these curves were performed starting from\nrepresentative microstates of different phases of the system. We show that the\ncurves are characterized by phase-specific features in such a way that a\npattern recognition algorithm predicts the phase of the initial microstate with\ngood reliability. This achievement represents a new strategy to identify phases\nin ASIs, easier and more accessible than magnetic imaging techniques normally\nused for this task.",
        "positive": "Special frequencies in reflection spectra of Bragg multiple quantum well\n  structures: We have studied theoretically optical reflection spectra from the Bragg\nmultiple quantum well structures. We give an analytical explanation of the\npresence of two special frequencies in the spectra at which the reflection\ncoefficient weakly depends on the quantum well number. The influence of the\nexciton nonradiative damping on the reflection spectra has been analyzed. It\nhas been shown that allowance for the dielectric contrast gives rise to the\nthird special frequency at which the contributions to the reflectivity related\nto the dielectric contrast and the exciton resonance mutually compensate one\nanother."
    },
    {
        "anchor": "Observation of non-Abelian topological semimetals and their phase\n  transitions: Topological phases of matter lie at the heart of physics, connecting elegant\nmathematical principles to real materials that are believed to shape future\nelectronic and quantum computing technologies. To date, studies in this\ndiscipline have almost exclusively been restricted to single-gap band topology\nbecause of the Fermi-Dirac filling effect. Here, we theoretically analyze and\nexperimentally confirm a novel class of multi-gap topological phases, which we\nwill refer to as non-Abelian topological semimetals, on kagome geometries.\nThese unprecedented forms of matter depend on the notion of Euler class and\nframe charges which arise due to non-Abelian charge conversion processes when\nband nodes of different gaps are braided along each other in momentum space. We\nidentify such exotic phenomena in acoustic metamaterials and uncover a rich\ntopological phase diagram induced by the creation, braiding and recombination\nof band nodes. Using pump-probe measurements, we verify the non-Abelian charge\nconversion processes where topological charges of nodes are transferred from\none gap to another. Moreover, in such processes, we discover symmetry-enforced\nintermediate phases featuring triply-degenerate band nodes with unique\ndispersions that are directly linked to the multi-gap topological invariants.\nFurthermore, we confirm that edge states can faithfully characterize the\nmulti-gap topological phase diagram. Our study unveils a new regime of\ntopological phases where multi-gap topology and non-Abelian charges of band\nnodes play a crucial role in understanding semimetals with inter-connected\nmultiple bands.",
        "positive": "Disordered Dirac Fermions: Multifractality Termination and Logarithmic\n  Conformal Field Theories: We reexamine in detail the problem of fermions interacting with a non-Abelian\nrandom vector potential. Without resorting to the replica or supersymmetry\napproaches, we show that in the limit of infinite disorder strength the theory\npossesses an exact solution which takes the form of a logarithmic conformal\nfield theory. We show that the proper treatment of the locality conditions in\nthe SU(2) theory leads to the termination of the multifractal spectrum, or in\nother words to the termination of the infinite hierarchies of\nnegative-dimensional operators that were thought to occur. Based on arguments\nof logarithmic degeneracies, we conjecture that such a termination mechanism\nshould be present for general SU(N). Moreover, our results lead to the\nconclusion that the previous replica solution of this problem yields incorrect\nresults."
    },
    {
        "anchor": "AC conductivity of a quantum Hall line junction: We present a microscopic model for calculating the AC conductivity of a\nfinite length line junction made up of two counter or co-propagating single\nmode quantum Hall edges with possibly different filling fractions. The effect\nof density-density interactions and the tunneling conductance (\\sigma), between\nthe two edges, is considered, and exact expressions are derived for the AC\nconductivity as a function of the frequency (\\omega), the length of the line\njunction and other parameters of the system. We reproduce the results of Phys.\nRev. B 78, 085430 (2008) in the DC limit (\\omega \\to 0), and generalize those\nresults for an interacting system. As a function of \\omega, the AC conductivity\nshows significant oscillations if \\sigma is small; the oscillations become less\nprominent as \\sigma increases. A renormalization group analysis shows that the\nsystem may be in a metallic or an insulating phase depending on the strength of\nthe interactions. We discuss the experimental implications of this for the\nbehavior of the AC conductivity at low temperatures.",
        "positive": "Stimulated Raman Adiabatic control of a nuclear spin in diamond: Coherent manipulation of nuclear spins is a highly desirable tool for both\nquantum metrology and quantum computation. However, most of the current\ntechniques to control nuclear spins lack of being fast impairing their\nrobustness against decoherence. Here, based on Stimulated Raman Adiabatic\nPassage, and its modification including shortcuts to adiabaticity, we present a\nfast protocol for the coherent manipulation of nuclear spins. Moreover, we show\nhow to initialise a nuclear spin starting from a thermal state, and how to\nimplement Raman control for performing Ramsey spectroscopy to measure the\ndynamical and geometric phases acquired by nuclear spins."
    },
    {
        "anchor": "Midinfrared Third Harmonic Generation from Macroscopically Aligned\n  Ultralong Single-Wall Carbon Nanotubes: We report the observation of strong third harmonic generation from a\nmacroscopic array of aligned ultralong single-wall carbon nanotubes (SWCNTs)\nwith intense midinfrared radiation. Through power-dependent experiments, we\ndetermined the absolute value of the third-order nonlinear optical\nsusceptibility, $\\chi^{(3)}$, of our SWCNT film to be 5.53 $\\times$ 10$^{-12}$\nesu, three orders of magnitude larger than that of the fused silica reference\nwe used. Taking account of the filling factor of 8.75% for our SWCNT film, we\nestimate a $\\chi^{(3)}$ of 6.32 $\\times$ 10$^{-11}$ esu for a fully dense film.\nFurthermore, through polarization-dependent experiments, we extracted all the\nnonzero elements of the $\\chi^{(3)}$ tensor, determining the magnitude of the\nweaker tensor elements to be $\\sim$1/6 of that of the dominant\n$\\chi^{(3)}_{zzzz}$ component.",
        "positive": "Topological magnetoplasmon: Classical wave fields are real-valued, ensuring the wave states at opposite\nfrequencies and momenta to be inherently identical. Such a particle-hole\nsymmetry can open up new possibilities for topological phenomena in classical\nsystems. Here we show that the historically studied two-dimensional (2D)\nmagnetoplasmon, which bears gapped bulk states and gapless one-way edge states\nnear zero frequency, is topologically analogous to the 2D topological $p+\\Ii p$\nsuperconductor with chiral Majorana edge states and zero modes. We further\npredict a new type of one-way edge magnetoplasmon at the interface of opposite\nmagnetic domains, and demonstrate the existence of zero-frequency modes bounded\nat the peripheries of a hollow disk. These findings can be readily verified in\nexperiment, and can greatly enrich the topological phases in bosonic and\nclassical systems."
    },
    {
        "anchor": "Coupling a nano-particle with isothermal fluctuating hydrodynamics:\n  Coarse-graining from microscopic to mesoscopic dynamics: We derive a coarse-grained description of the dynamics of a nanoparticle\nimmersed in an isothermal simple fluid by performing a systematic coarse\ngraining of the underlying microscopic dynamics. As coarse-grained or relevant\nvariables we select the position of the nanoparticle and the \\emph{total} mass\nand momentum density field of the fluid, which are locally conserved slow\nvariables because they are defined to include the contribution of the\nnanoparticle. The theory of coarse graining based on the Zwanzing projection\noperator leads us to a system of stochastic \\emph{ordinary} differential\nequations (SODEs) that are closed in the relevant variables. We demonstrate\nthat our discrete coarse-grained equations are consistent with a\nPetrov-Galerkin finite-element discretization of a system of formal stochastic\n\\emph{partial} differential equations (SPDEs) which resemble previously-used\nphenomenological models based on fluctuating hydrodynamics. Under suitable\napproximations we obtain \\emph{closed} approximations of the coarse-grained\ndynamics in a manner which gives them a clear physical interpretation, and\nprovides \\emph{explicit} microscopic expressions for all of the coefficients\nappearing in the closure. Our work leads to a model for dilute nanocolloidal\nsuspensions that can be simulated effectively using feasibly short molecular\ndynamics simulations as input to a FEM fluctuating hydrodynamic solver.",
        "positive": "Chromium-Induced Ferromagnetism with Perpendicular Anisotropy in\n  Topological Crystalline Insulator SnTe (111) Thin Films: Topological crystalline insulator (TCI) is a recently-discovered topological\nphase of matter. It possesses multiple Dirac surface states, which are\nprotected by the crystal symmetry. This is in contrast to the time reversal\nsymmetry that is operative in the well-known topological insulators. In the\npresence of a Zeeman field and/or strain, the multiple Dirac surface states are\ngapped. The high-Chern-number quantum anomalous Hall (QAH) state is predicted\nto emerge if the chemical potential resides in all the Zeeman gaps. Here, we\nuse molecular beam epitaxy to grow 12 double layer (DL) pure and Cr-doped SnTe\n(111) thin film on heat-treated SrTiO3 (111) substrate using a quintuple layer\nof insulating (Bi0.2Sb0.8)2Te3 topological insulator as a buffer film. The Hall\ntraces of Cr-doped SnTe film at low temperatures display square hysteresis\nloops indicating long-range ferromagnetic order with perpendicular anisotropy.\nThe Curie temperature of the 12DL Sn0.9Cr0.1Te film is ~ 110 K. Due to the\nchemical potential crossing the bulk valence bands, the anomalous Hall\nresistance of 12DL Sn0.9Cr0.1Te film is substantially lower than the predicted\nquantized value (~1/4 h/e2). It is possible that with systematic tuning the\nchemical potential via chemical doping and electrical gating, the\nhigh-Chern-number QAH state can be realized in the Cr-doped SnTe (111) thin\nfilm."
    },
    {
        "anchor": "Sensing electrons during an adiabatic coherent transport passage: We study the detection of electrons undergoing coherent transfer via\nadiabatic passage (CTAP) in a triple quantum-dot system with a quantum\npoint-contact sensing the change of the middle dot. In the ideal scenario, the\nprotocol amounts to perfect change transfer between the external dots with\nvanishing occupation of the central dot at all times, rendering the measurement\nand its backaction moot. Nevertheless, even with minor corrections to the\nprotocol, a small population builds up in the central dot. We study the\nmeasurement backaction by a Bayesian formalism simulation of an instantaneous\ndetection at the time of maximal occupancy of the dot. We show that the\ninterplay between the measurement backaction and the non-adiabatic dynamics\ninduce a change of the success probability of the protocol, which\nquantitatively agrees with a continuous detection treatment. We introduce a\ncorrelated measurement signal to certify the non-occupancy of the central dot\nfor a successful CTAP protocol, which, in the weak measurement limit, confirms\na vanishing occupation of the central dot. Our proposed correlated-signal\npurports that proper experimental method by which to confirm CTAP.",
        "positive": "Critical currents and self organization in quantum Hall bilayers: We present a theory of the critical interlayer tunneling current in a\ndisordered quantum Hall bilayer at total filling factor one, allowing for the\neffect of static vortices. In agreement with recent experiments [Phys. Rev. B\n80, 165120 (2009); ibid. 78, 075302 (2008)], we find that this critical current\nis proportional to the area of the sample and is comparable in magnitude to\nobserved values. This reflects the formation of a Bean critical state as a\nresult of current injection at the boundary. We predict a crossover to a\ncritical current proportional to the square-root of area as either sample size\nor electron density decreases. We also predict a peak in the critical current\nas the electron density varies at fixed layer separation."
    },
    {
        "anchor": "Stable and manipulable Bloch point: The prediction of magnetic skyrmions being used to change the way we store\nand process data has led to materials with Dzyaloshinskii-Moriya interaction\ncoming into the focus of intensive research. So far, studies have looked mostly\nat magnetic systems composed of materials with single chirality. In a search\nfor potential future spintronic devices, combination of materials with\ndifferent chirality into a single system may represent an important new avenue\nfor research. Using finite element micromagnetic simulations, we study an FeGe\ndisk with two layers of different chirality. We show that for particular\nthicknesses of layers, a stable Bloch point emerges at the interface between\ntwo layers. In addition, we demonstrate that the system undergoes hysteretic\nbehaviour and that two different types of Bloch point exist. These\n`head-to-head' and `tail-to-tail' Bloch point configurations can, with the\napplication of an external magnetic field, be switched between. Finally, by\ninvestigating the time evolution of the magnetisation field, we reveal the\ncreation mechanism of the Bloch point. Our results introduce a stable and\nmanipulable Bloch point to the collection of particle-like state candidates for\nthe development of future spintronic devices.",
        "positive": "Spin singlet-triplet transition in a Si-based two-electron double\n  quantum dot molecule: We report a successful measurement of the magnetic field-induced spin\nsinglet-triplet transition in silicon-based coupled dot systems. Our specific\nexperimental scheme incorporates a lateral gate-controlled Coulomb-blockaded\nstructure in Si to meet the proposed scheme of Loss and DiVincenzo [1], and a\nnon-equilibrium single-electron tunneling technique to probe the fine energy\nsplitting between the spin singlet and triplet, which varies as a function of\napplying magnetic fields and interdot coupling constant. Our results,\nexhibiting the singlet-triplet crossing at a magnetic field for various\ninterdot coupling constants, are in agreement with the theoretical predictions,\nand give the first experimental demonstration of the possible spin swapping\noccurring in the coupled double dot systems with magnetic field. *Electronic\naddress: jungchoi@chungbuk.ac.kr [1] D. Loss and D. P. DiVincenzo, Phys. Rev. A\n57, 120 (1998)."
    },
    {
        "anchor": "Boron Nitride Substrates for High Mobility Chemical Vapor Deposited\n  Graphene: Chemical vapor deposited (CVD) graphene is often presented as a scalable\nsolution to graphene device fabrication, but to date such graphene has\nexhibited lower mobility than that produced by exfoliation. Using a boron\nnitride underlayer, we achieve mobilities as high as 37,000 cm^2/Vs, an order\nof magnitude higher than commonly reported for CVD graphene and better than\nmost exfoliated graphene. This result demonstrates that the barrier to\nscalable, high mobility CVD graphene is not the growth technique but rather the\nchoice of a substrate that minimizes carrier scattering.",
        "positive": "RKKY interaction in gapped or doped graphene: In our previous work (E. Kogan, Phys. Rev. B {\\bf 84}, 115119 (2011)) we\ncalculated RKKY interaction between two magnetic impurities in pristine\ngraphene using the Green's functions (GF) in the coordinate -- imaginary time\nrepresentation. Now we show that the calculations of the GF in this\nrepresentation can be simplified by using the Feynman's trick, which allows to\neasily calculate RKKY interaction in gapped graphene. We also present\ncalculations of the RKKY interaction in gapped or doped graphene using the\ncoordinate -- imaginary frequency representation. Both representations,\ncorresponding to calculation of the bubble diagram in Euclidean space, have an\nimportant advantage over those corresponding to calculation in Minkowskii\nspace, which are very briefly reviewed in the Appendix to the present work. The\nformer, in distinction to the latter, operate only with the convergent\nintegrals from the start to the end of the calculation."
    },
    {
        "anchor": "The Interplay of Charge and Spin in Quantum Dots: The Ising Case: The physics of quantum dots is succinctly depicted by the {\\it Universal\nHamiltonian}, where only zero mode interactions are included. In the case where\nthe latter involve charging and isotropic spin-exchange terms, this would lead\nto a non-Abelian action. Here we address an Ising spin-exchange interaction,\nwhich leads to an Abelian action. The analysis of this simplified yet\nnon-trivial model shed some light on a more general case of charge and spin\nentanglement. We present a calculation of the tunneling density of states and\nof the dynamic magnetic susceptibility. Our results are amenable to\nexperimental study and may allow for an experimental determination of the\nexchange interaction strength.",
        "positive": "Control of Exciton Transport using Quantum Interference: It is shown that quantum interference can be employed to create an exciton\ntransistor. An applied potential gates the quasi-particle motion and also\ndiscriminates between quasi-particles of differing binding energy. When\nimplemented within nanoscale assemblies, such control elements could mediate\nthe flow of energy and information. Quantum interference can also be used to\ndissociate excitons as an alternative to using heterojunctions. A finite\nmolecular setting is employed to exhibit the underlying discrete, two-particle,\nmesoscopic analog to Fano anti-resonance. Selected entanglement measures are\nshown to distinguish regimes of behavior which cannot be resolved from\npopulation dynamics alone."
    },
    {
        "anchor": "Thermally and Molecularly Stimulated Relaxation of Hot Phonons in\n  Suspended Carbon Nanotubes: The high-bias electrical transport properties of suspended metallic\nsingle-walled carbon nanotubes (SWNTs) are investigated at various temperatures\nin vacuum, in various gases and when coated with molecular solids. It is\nrevealed that non-equilibrium optical phonon effects in suspended nanotubes\ndecrease as the ambient temperature increases. Gas molecules surrounding\nsuspended SWNTs assist the relaxation of hot phonons and afford enhanced\ncurrent flow along nanotubes. Molecular solids of carbon dioxide frozen onto\nsuspended SWNTs quench the non-equilibrium phonon effect. The discovery of\nstrong environmental effects on high current transport in nanotubes is\nimportant to high performance nanoelectronics applications of 1D nanowires in\ngeneral.",
        "positive": "A cascade of phase transitions in an orbitally mixed half-filled Landau\n  level: Half-filled Landau levels host an emergent Fermi-liquid which displays an\ninstability towards pairing, culminating in a gapped even-denominator\nfractional quantum Hall ground state. While this pairing may be probed by\ntuning the polarization of carriers in competing orbital and spin degrees of\nfreedom, sufficiently high quality platforms offering such tunability remain\nfew. Here we explore the ground states at filling factor $\\nu$ = 5/2 in\nZnO-based two-dimensional electron systems through a forced intersection of\nopposing spin branches of Landau levels taking quantum numbers $N$ = 1 and 0.\nWe reveal a cascade of phases with distinct magnetotransport features including\na gapped phase polarized in the $N$ = 1 level and a compressible phase in N =\n0, along with an unexpected Fermi-liquid, a second gapped, and a strongly\nanisotropic nematic-like phase at intermediate polarizations when the levels\nare near degeneracy. The phase diagram is produced by analyzing the proximity\nof the intersecting levels and highlights the excellent reproducibility and\ncontrollability ZnO offers for exploring exotic fractionalized electronic\nphases."
    },
    {
        "anchor": "Tunable interplay between light and heavy electrons in twisted trilayer\n  graphene: In strongly interacting systems with multiple energy bands, the interplay\nbetween electrons with different effective masses and the enlarged Hilbert\nspace drives intricate correlated phenomena that do not occur in single-band\nsystems. Recently, magic-angle twisted trilayer graphene (MATTG) has emerged as\na promising tunable platform for such investigations: the system hosts both\nslowly dispersing, \"heavy\" electrons inhabiting its flat bands as well as\ndelocalized \"light\" bands that disperse as free Dirac fermions. Most\nremarkably, superconductivity in twisted trilayer graphene and multilayer\nanalogues with additional dispersive bands exhibits Pauli limit violation and\nspans a wider range of phase space compared to that in twisted bilayer\ngraphene, where the dispersive bands are absent. This suggests that the\ninteractions between different bands may play a fundamental role in stabilizing\ncorrelated phases in twisted graphene multilayers. Here, we elucidate the\ninterplay between the light and heavy electrons in MATTG as a function of\ndoping and magnetic field by performing local compressibility measurements with\na scanning single-electron-transistor microscope. We establish that commonly\nobserved resistive features near moir\\'e band fillings $\\nu$=-2, 1, 2 and 3\nhost a finite population of light Dirac electrons at the Fermi level despite a\ngap opening in the flat band sector. At higher magnetic field and near charge\nneutrality, we discover a new type of phase transition sequence that is robust\nover nearly 10 micrometers but exhibits complex spatial dependence. Mean-field\ncalculations establish that these transitions arise from the competing\npopulation of the two subsystems and that the Dirac sector can be viewed as a\nnew flavor analogous to the spin and valley degrees of freedom.",
        "positive": "Optical Properties of Graphene Nanoflakes: Shape Matters: In recent years there has been significant debate on whether the edge type of\ngraphene nanoflakes (GNF) or graphene quantum dots (GQD) are relevant for their\nelectronic structure, thermal stability and optical properties. Using computer\nsimulations, we have proven that there is a fundamental difference in the\ncalculated absorption spectra between samples of the same shape, similar size\nbut different edge type, namely, armchair or zigzag edges. These can be\nexplained by the presence of electronic structures near the Fermi level which\nare localized on the edges. These features are also evident from the dependence\nof band gap on the GNF size, which shows three very distinct trends for\ndifferent shapes and edge geometries."
    },
    {
        "anchor": "Lasing in planar semiconductor diodes: We present a planar laser diode based on a simple fabrication scheme\ncompatible with virtually any geometry accessible by standard semiconductor\nlithography technique. We show that our lasers exhibit ~1 GHz\n-3dB-modulation-bandwidth already in this prototypical implementation.\nDirections for a significant speed increase are discussed.",
        "positive": "Quantum Hall and Light Responses in a 2D Topological Semimetal: We have recently identified a protected topological semimetal in graphene\nwhich presents a zero-energy edge mode robust to disorder and interactions.\nHere, we address the characteristics of this semimetal and show that the\n$\\mathbb{Z}$ topological invariant of the Hall conductivity associated to the\nlowest energy band can be equivalently measured from the resonant response to\ncircularly polarized light resolved at the Dirac points. The (non-quantized)\nconductivity responses of the intermediate energy bands, including the Fermi\nsurface, also give rise to a $\\mathbb{Z}_2$ invariant. We emphasize on the\nbulk-edge correspondence as a half-topological protected semimetal, i.e. one\nspin-population polarized in the plane is in the insulating phase related to\nthe robust edge mode while the other is in the metallic regime. The quantized\ntransport at the edges is also equivalent to a $\\frac{1}{2}-\\frac{1}{2}$\nconductance for spin polarizations along $z$ direction. We also build a\nparallel between the topological Hall response through the quantized light\nresponse at the Dirac points and a pair of half numbers (half Skyrmions)."
    },
    {
        "anchor": "Comment on `Origin of combination frequencies in quantum magnetic\n  oscillations of two-dimensional multiband metals' by T. Champel [Phys. Rev. B\n  65, 153403 (2002); cond-mat/0110154]: We analyze the applicability of our analytical theory of combination\nharmonics in canonical low-dimensional multi-band Fermi liquids, which was\nrecently criticized by Champel (Phys. Rev. B 65, 153403 (2002)). It is shown\nthat his claim that our analytical theory does not apply at low temperatures\nand in clean samples, is incorrect. We demonstrate that the analytical theory\nof combination harmonics is in excellent agreement with the exact numerical\nresults even at zero temperature and for clean systems, which are the most\nchallenging for an analytical description.",
        "positive": "Three-Dimensional Magnetic Page Memory: The increasing need to store large amounts of information with an\nultra-dense, reliable, low power and low cost memory device is driving\naggressive efforts to improve upon current perpendicular magnetic recording\ntechnology. However, the difficulties in fabricating small grain recording\nmedia while maintaining thermal stability and a high signal-to-noise ratio\nmotivate development of alternative methods, such as the patterning of magnetic\nnano-islands and utilizing energy-assist for future applications. In addition,\nboth from sensor and memory perspective three-dimensional spintronic devices\nare highly desirable to overcome the restrictions on the functionality in the\nplanar structures. Here we demonstrate a three-dimensional magnetic-memory\n(magnetic page memory) based on thermally assisted and stray-field induced\ntransfer of domains in a vertical stack of magnetic nanowires with\nperpendicular anisotropy. Using spin-torque induced domain shifting in such a\ndevice with periodic pinning sites provides additional degrees of freedom by\nallowing lateral information flow to realize truly three-dimensional\nintegration."
    },
    {
        "anchor": "Time-domain quantum interference in graphene: The electron momentum density obtained from the Schwinger-like mechanism is\nevaluated for a graphene sample immersed in a homogeneous time-dependent\nelectric field. Based on the analogy between graphene low-energy electrons and\nquantum electrodynamics (QED), numerical techniques borrowed from strong field\nQED are employed and compared to approximate analytical approaches. It is\ndemonstrated that for some range of experimentally accessible parameters, the\npair production proceeds by sequences of adiabatic evolutions followed by\nnon-adiabatic Landau-Zener transitions, reminiscent of the Kibble-Zurek\nmechanism describing topological defect density in second order phase\ntransitions. For some field configurations, this yields interference patterns\nin momentum space which are explained in terms of the adiabatic-impulse model\nand the Landau-Zener-St\\\"{u}ckelberg interferometry.",
        "positive": "Computational study of exciton generation in suspended carbon nanotube\n  transistors: Optical emission from carbon nanotube transistors (CNTFETs) has recently\nattracted significant attention due to its potential applications. In this\npaper, we use a self-consistent numerical solution of the Boltzmann transport\nequation in the presence of both phonon and exciton scattering to present a\ndetailed study of the operation of a partially suspended CNTFET light emitter,\nwhich has been discussed in a recent experiment. We determine the energy\ndistribution of hot carriers in the CNTFET, and, as reported in the experiment,\nobserve localized generation of excitons near the trench-substrate junction and\nan exponential increase in emission intensity with a linear increase in current\nversus gate voltage. We further provide detailed insight into device operation,\nand propose optimization schemes for efficient exciton generation; a deeper\ntrench increases the generation efficiency, and use of high-k substrate oxides\ncould lead to even larger enhancements."
    },
    {
        "anchor": "Exciton bound by distant ionized donor in two-dimensional GaAs/AlGaAs\n  quantum well: The ground state energy of exciton bound by distant ionized donor impurity in\nquasi-two-dimensional GaAs/AlGaAs semiconductor quantum well (QW) is studied\ntheoretically within the Hartree approach in the effective mass approximation.\nThe influence of the distance between QW plane and ionized donor, as well as of\nthe magnetic field aligned across the QW plane and varying dielectric constant\nof the barrier material on the stability of exciton bound by ionized donor\nimpurity is analyzed and discussed.",
        "positive": "Skyrmion robustness in non-centrosymmetric magnets with axial symmetry:\n  The role of anisotropy and tilted magnetic fields: We investigate the stability of N\\'eel skyrmions against tilted magnetic\nfields, in polar magnets with uniaxial anisotropy ranging from easy-plane to\neasy-axis type. We construct the corresponding phase diagrams and investigate\nthe internal structure of skewed skyrmions with displaced cores. We find that\nmoderate easy-plane anisotropy increases the stability range of N\\'eel\nskyrmions for fields along the symmetry axis, while moderate easy-axis\nanisotropy enhances their robustness against tilted magnetic fields. We stress\nthat the direction, along which the skyrmion cores are shifted, depends on the\nsymmetry of the underlying crystal lattice. The cores of N\\'eel skyrmions,\nrealized in polar magnets with C$_{nv}$ symmetry, are displaced either along or\nopposite to the off-axis (in-plane) component of the magnetic field depending\non the rotation sense of the magnetization, dictated by the sign of the\nDzyaloshinskii constant. The core shift of antiskyrmions, present in chiral\nmagnets with D$_{2d}$ symmetry, depends on the in-plane orientation of the\nmagnetic field and can be parallel, anti-parallel, or perpendicular to it. We\nargue that the role of anisotropy in magnets with axially symmetric crystal\nstructure is different from that in cubic helimagnets. Our results can be\napplied to address recent experiments on polar magnets with C$_{3v}$ symmetry,\nGaV$_4$S$_8$ and GaV$_4$Se$_8$."
    },
    {
        "anchor": "Confined states in graphene quantum blisters: Bilayer graphene samples may exhibit regions where the two layers are locally\ndelaminated forming a so-called quantum blister in the graphene sheet. Electron\nand hole states can be confined in this graphene quantum blisters (GQB) by\napplying a global electrostatic bias. We scrutinize the electronic properties\nof these confined states under the variation of interlayer bias, coupling, and\nblister's size. The spectra display strong anti-crossings due to the coupling\nof the confined states on upper and lower layers inside the blister. These\nspectra are layer localized where the respective confined states reside on\neither layer or equally distributed. For finite angular momentum, this layer\nlocalization can be at the edge of the blister and corresponds to degenerate\nmodes of opposite momenta. Furthermore, the energy levels in GQB exhibit\nelectron-hole symmetry that is sensitive to the electrostatic bias. Finally, we\ndemonstrate that confinement in GQB persists even in the presence of a\nvariation in the inter-layer coupling.",
        "positive": "Excitations and superfluidity in non-equilibrium Bose-Einstein\n  condensates of exciton-polaritons: We present a generic model for the description of non-equilibrium\nBose-Einstein condensates, suited for the modelling of non-resonantly pumped\npolariton condensates in a semiconductor microcavity. The excitation spectrum\nand scattering of the non-equilibrium condensate with a defect are discussed."
    },
    {
        "anchor": "Active Valley-topological Plasmonic Crystal in Metagate-tuned Graphene: A valley plasmonic crystal for graphene surface plasmons (GSPs) is proposed.\nWe demonstrate that a designer metagate, placed within a few nanometers from\ngraphene, can be used to impose a triangular periodic Fermi energy landscape on\nthe latter. For specific metagate geometries and bias voltages, the combined\nmetagate-graphene structure is shown to produce sufficiently strong Bragg\nscattering of GSPs to produce complete propagation bandgaps, and to impart the\nGSPs with nontrivial valley-linked topological properties. Valley-selective\nkink states supported by a domain wall between differently patterned metagates\nare shown to propagate without reflections along sharply curved interfaces\nowing to suppressed inter-valley scattering. Our approach paves the way for\nnon-magnetic dynamically reconfigurable topological nanophotonic devices.",
        "positive": "Quantum Fluctuation of the Quantum Geometric Tensor and its\n  Manifestation as Intrinsic Hall Signatures in Time-Reversal Invariant Systems: In time-reversal invariant systems, all charge Hall effects predicted so far\nare extrinsic effects due to the dependence on the relaxation time. We explore\nintrinsic Hall signatures by studying quantum noise spectrum of the Hall\ncurrent in time-reversal invariant systems, and discover intrinsic thermal Hall\nnoises in both linear and nonlinear regimes. As the band geometric\ncharacteristics, quantum geometric tensor and Berry curvature play critical\nroles in various Hall effects, so are their quantum fluctuations. It is found\nthat the thermal Hall noise in linear order of the electric field is purely\nintrinsic, and the second-order thermal Hall noise has both intrinsic and\nextrinsic contributions. In particular, the intrinsic part of the second-order\nthermal Hall noise is a manifestation of the quantum fluctuation of quantum\ngeometric tensor, which widely exists as long as Berry curvature is nonzero.\nThese intrinsic thermal Hall noises provide direct measurable means to band\ngeometric information, including Berry curvature related quantities and quantum\nfluctuation of quantum geometric tensor."
    },
    {
        "anchor": "Giant spin rotation in the normal metal/quantum spin Hall junction: We study theoretically reflection problem in the junction between a normal\nmetal and an insulator characterized by a parameter $M$, which is a usual\ninsulator for $M>0$ or a quantum spin Hall system for $M<0$. The spin rotation\nangle $\\alpha$ at the reflection is obtained in the plane of $M$ and the\nincident angle $\\theta$ measured from the normal to the interface. The $\\alpha$\nshows rich structures around the quantum critical point M=0 and $\\theta=0$,\ni.e., $\\alpha$ can be as large as $\\sim \\pi$ at an incident angle in the quatum\nspin Hall case $M<0$ because the helical edge modes resonantly enhance the spin\nrotation, which can be used to map the energy dispersion of the helical edge\nmodes. As an experimentally relevant system, we also study spin rotation effect\nin quantum spin Hall/normal metal/quantum spin Hall trilayer junction.",
        "positive": "Challenges on Optical Printing of Colloidal Nanoparticles: While colloidal chemistry provides ways to obtain a great variety of\nnanoparticles, with different shapes, sizes, material composition, and surface\nfunctions, their controlled deposition and combination on arbitrary positions\nof substrates remains a considerable challenge. Over the last ten years,\noptical printing arose as a versatile method to achieve this purpose for\ndifferent kinds of nanoparticles. In this article we review the state of the\nart of optical printing of single nanoparticles, and discuss its strengths,\nlimitations, and future perspectives, by focusing on four main challenges:\nprinting accuracy, resolution, selectivity, and nanoparticles photostability."
    },
    {
        "anchor": "Photoelectronic scoping of adatoms, atomic vacancies, and the outermost\n  layer of a surface: An effective yet simple means disclosed herewith has allowed us to gain the\natomistic, local, and quantitative information of bonds and electrons at sites\nsurrounding undercoordinated atoms, complementing the scanning tunneling\nmicroscopy/spectroscopy and photoelectron spectroscopy (XPS). Examining Rh and\nPt surfaces with and without adatoms and graphite surface with and without\natomic vacancies, we confirmed that: i) bonds between undercoordinated atoms\nbecome shorter and stronger; ii) subjective polarization happens to the valence\nelectrons of defects or adatoms by the densely entrapped bonding electrons,\nwhich in turn screens and splits the crystal field and hence the core band of\nthe specimen.",
        "positive": "Parity (and time-reversal) anomaly in a semiconductor: The physics of a parity anomaly, potentially observable in a narrow-gap\nsemiconductor, is revisited. Fradkin, Dagotto, and Boyanovsky have suggested\nthat a Hall current of anomalous parity can be induced by a Peierls distortion\non a domain wall. I argue that a perturbation inducing the parity anomaly must\nbreak the time reversal symmetry, which rules out the Peierls distortion as a\npotential cause. I list all possible perturbations that can generate the\nanomaly."
    },
    {
        "anchor": "Fundamental efficiency bound for coherent energy transfer in\n  nanophotonics: We derive a unified quantum theory of coherent and incoherent energy transfer\nbetween two atoms (donor and acceptor) valid in arbitrary Markovian\nnanophotonic environments. Our theory predicts a fundamental bound $\\eta_{max}\n= \\frac{\\gamma_a}{\\gamma_d + \\gamma_a}$ for energy transfer efficiency arising\nfrom the spontaneous emission rates $\\gamma_{d}$ and $\\gamma_a$ of the donor\nand acceptor. We propose the control of the acceptor spontaneous emission rate\nas a new design principle for enhancing energy transfer efficiency. We predict\nan experiment using mirrors to enhance the efficiency bound by exploiting the\ndipole orientations of the donor and acceptor. Of fundamental interest, we show\nthat while quantum coherence implies the ultimate efficiency bound has been\nreached, reaching the ultimate efficiency does not require quantum coherence.\nOur work paves the way towards nanophotonic analogues of efficiency enhancing\nenvironments known in quantum biological systems.",
        "positive": "Twist-controlled resonant tunnelling in graphene-boron nitride-graphene\n  heterostructures: Recent developments in the technology of van der Waals heterostructures made\nfrom two-dimensional atomic crystals have already led to the observation of new\nphysical phenomena, such as the metal-insulator transition and Coulomb drag,\nand to the realisation of functional devices, such as tunnel diodes, tunnel\ntransistors and photovoltaic sensors. An unprecedented degree of control of the\nelectronic properties is available not only by means of the selection of\nmaterials in the stack but also through the additional fine-tuning achievable\nby adjusting the built-in strain and relative orientation of the component\nlayers. Here we demonstrate how careful alignment of the crystallographic\norientation of two graphene electrodes, separated by a layer of hexagonal boron\nnitride (hBN) in a transistor device, can achieve resonant tunnelling with\nconservation of electron energy, momentum and, potentially, chirality. We show\nhow the resonance peak and negative differential conductance in the device\ncharacteristics induces a tuneable radio-frequency oscillatory current which\nhas potential for future high frequency technology."
    },
    {
        "anchor": "Interferometric Measurement of Far Infrared Plasmons via Resonant\n  Homodyne Mixing: We present an electrically tunable terahertz two dimensional plasmonic\ninterferometer with an integrated detection element that down converts the\nterahertz fields to a DC signal. The integrated detector utilizes a resonant\nplasmonic homodyne mixing mechanism that measures the component of the plasma\nwaves in-phase with an excitation field functioning as the local oscillator.\nPlasmonic interferometers with two independently tuned paths are studied. These\ndevices demonstrate a means for developing a spectrometer-on-a-chip where the\ntuning of electrical length plays a role analogous to that of physical path\nlength in macroscopic Fourier transform interferometers.",
        "positive": "Fano effect in a Josephson junction with a quantum dot: We theoretically investigate the Fano effect in dc Josephson current at the\nabsolute zero of temperature. The system under consideration is a double-path\nJosephson junction in which one path is through an insulating barrier and the\nother one is through a quantum dot (QD). Here the Kondo temperature is assumed\nto be much smaller than the superconducting gap, and the Coulomb interaction\ninside the QD is treated by the Hartree-Fock approximation. It is shown that\nthe Josephson critical current exhibits an asymmetric resonance against the QD\nenergy level. This behavior is caused by the interference between the two\ntunneling processes between the superconductors; the direct tunneling across\nthe insulating barrier and the resonant one through the QD. Moreover, we find\nthat the Josephson critical current changes its sign around the resonance when\nthe Coulomb interaction is sufficiently strong. Our results suggest that\n0-$\\pi$ transition is induced by the cooperation of the Fano effect and the\nCoulomb interaction inside the QD."
    },
    {
        "anchor": "Spectroscopic properties of large open quantum-chaotic cavities with and\n  without separated time scales: The spectroscopic properties of an open large Bunimovich cavity are studied\nnumerically in the framework of the effective Hamiltonian formalism. The cavity\nis opened by attaching leads to it in four different ways. In some cases,\nshort-lived and long-lived resonance states coexist. The short-lived states\ncause traveling waves in the transmission while the long-lived ones generate\nsuperposed fluctuations. The traveling waves oscillate as a function of energy.\nThey are not localized in the interior of the large chaotic cavity. In other\ncases, the transmission takes place via standing waves with an intensity that\nclosely follows the profile of the resonances. In all considered cases, the\nphase rigidity fluctuates with energy. It is mostly near to its maximum value\nand agrees well with the theoretical value for the two-channel case. As shown\nin the foregoing paper \\cite{1}, all cases are described well by the Poisson\nkernel when the calculation is restricted to an energy region in which the\naverage $S$ matrix is (nearly) constant.",
        "positive": "Dissipation and Tunnelling in Quantum Hall Bilayers: We discuss the interplay between transport and intrinsic dissipation in\nquantum Hall bilayers, within the framework of a simple thought experiment. We\ncompute, for the first time, quantum corrections to the semiclassical dynamics\nof this system. This allows us to re-interpret tunnelling measurements on these\nsystems. We find a strong peak in the zero-temperature tunnelling current that\narises from the decay of Josephson-like oscillations into incoherent charge\nfluctuations. In the presence of an in-plane field, resonances in the\ntunnelling current develop an asymmetric lineshape."
    },
    {
        "anchor": "Confinement and edge effects on atomic collapse in graphene nanoribbons: Atomic collapse in graphene nanoribbons behaves in a fundamentally different\nway as compared to monolayer graphene, due to the presence of multiple energy\nbands and the effect of edges. For armchair nanoribbons we find that bound\nstates gradually transform into atomic collapse states with increasing impurity\ncharge. This is very different in zig-zag nanoribbons where multiple\nquasi-one-dimensional \\emph{bound states} are found that originates from the\nzero energy zig-zag edge states. They are a consequence of the flat band and\nthe electron distribution of these bound states exhibits two peaks. The lowest\nenergy edge state transforms from a bound state into an atomic collapse\nresonance and shows a distinct relocalization from the edge to the impurity\nposition with increasing impurity charge.",
        "positive": "Understanding magnetotransport signatures in networks of connected\n  permalloy nanowires: The change in electrical resistance associated with the application of an\nexternal magnetic field is known as the magnetoresistance (MR). The measured MR\nis quite complex in the class of connected networks of single-domain\nferromagnetic nanowires, known as \"artificial spin ice\", due to the\ngeometrically-induced collective behavior of the nanowire moments. We have\nconducted a thorough experimental study of the MR of a connected honeycomb\nartificial spin ice, and we present a simulation methodology for understanding\nthe detailed behavior of this complex correlated magnetic system. Our results\ndemonstrate that the behavior, even at low magnetic fields, can be\nwell-described only by including significant contributions from the vertices at\nwhich the legs meet, opening the door to new geometrically-induced MR\nphenomena."
    },
    {
        "anchor": "External field induced switching of tunneling current in the coupled\n  quantum dots: We investigated the tunneling current peculiarities in the system of two\ncoupled by means of the external field quantum dots (QDs) weakly connected to\nthe electrodes in the presence of Coulomb correlations. It was found that\ntuning of the external field frequency induces fast multiple tunneling current\nswitching and leads to the negative tunneling conductivity. Special role of\nmulti-electrons states was demonstrated. Moreover we revealed conditions for\nbistable behavior of the tunneling current in the coupled QDs with Coulomb\ncorrelations.",
        "positive": "Modifications of electron states, magnetization and persistent current\n  in a quantum dot by controlled curvature: In this work, we use the thin-layer quantization procedure to study the\nphysical implications due to curvature effects on a quantum dot in the presence\nof an external magnetic field. Among the various physical implications due to\nthe curvature of the system, we can mention the absence of the $m=0$ state is\nthe most relevant one. The absence of it affects the Fermi energy and\nconsequently the thermodynamic properties of the system. In the absence of\nmagnetic fields, we verify that the rotational symmetry in the lateral\nconfinement is preserved in the electronic states of the system and its\ndegeneracy with respect to the harmonicity of the confining potential is\nbroken. In the presence of a magnetic field, however, the energies of the\nelectronic states in a quantum dot with a curvature are greater than those\nobtained for a quantum dot in a flat space, and the profile of degeneracy\nchanges when the field is varied. We show that the curvature of the surface\nmodifies the number of subbands occupied in the Fermi energy. In the study of\nboth magnetization and persistent currents, we observe that Aharonov-Bohm-type\n(AB-type) oscillations are present, whereas de Haas-van Alphen-type (dHvA)\noscillations are not well defined."
    },
    {
        "anchor": "Topological magnon modes on honeycomb lattice with coupling textures: Topological magnon modes are expected to be useful for novel applications\nsuch as robust information propagation, since they are immune to backscattering\nand robust against disorder. Although there are several of theoretical\nproposals for topological magnon modes and growing experimental efforts for\nrealizing them by now, it is still desirable to add complementary insights on\nthis important phenomenon. Here, we propose a new scheme to achieve topological\nmagnon where only nearest-neighbour exchange couplings on honeycomb lattice are\nnecessary. In both ferromagnets and antiferromagnets, tuning exchange couplings\nbetween and inside hexagonal unit cells induces a topological state accompanied\nby a band inversion between p-orbital and d-orbital like magnon modes.\nTopological magnon modes appear at the interface between a topological domain\nand a trivial domain with magnon currents, which counterpropagate depending on\npseudospins originated from orbital angular momenta of magnon modes. This\nmimics the spin-momentum locking phenomenon in the quantum spin Hall effect.",
        "positive": "Interaction between carbon nanotubes and metals: Electronic properties,\n  stability, and sensing: The interactions between carbon nanotubes (CNTs) and metal adatoms as well as\nmetal contacts are studied by means of ab initio electronic structure\ncalculations. We show that the electronic properties of a semiconducting (8,4)\nCNT can be modified by small amounts of Pd adatoms. Such a decoration conserves\nthe piezoelectric properties of the CNT. Besides the electronic influence, the\nstability of a single adatom, which is of big importance for future technology\napplications, is investigated as well. We find only small energy barriers for\nthe diffusion of a Pd adatom on the CNT surface. Thus, single Pd adatoms will\nbe mobile at room temperature. Finally we present results for the interaction\nbetween a metallic (6,0) CNT and metal surfaces. Binding energies and distances\nfor Al, Cu, Pd, Ag, Pt, and Au are discussed and compared, showing remarkable\nagreement between the interaction of single metal atoms and metal surfaces with\nCNTs."
    },
    {
        "anchor": "Spin-pumping and inelastic electron tunneling spectroscopy in\n  topological insulators: We demonstrate that a quantum spin Hall current, spontaneously generated at\nthe edge of a two-dimensional topological insulator, acts as a source of\nspin-pumping for a magnetic impurity with uniaxial anisotropy. One can then\nmanipulate the impurity spin direction by means of an electrical current\nwithout using either magnetic electrodes or an external magnetic field.\nFurthermore we show that the unique properties of the quantum spin Hall\ntopological state have profound effects on the inelastic electron tunneling\nspectrum of the impurity. For low current densities inelastic spin-flip events\ndo not contribute to the conductance. As a consequence the conductance steps,\nnormally appearing at voltages corresponding to the spin excitations, are\ncompletely suppressed. In contrast an intense current leads to spin pumping and\ngenerates a transverse component of the impurity spin. This breaks the\ntopological phase yielding to the conductance steps.",
        "positive": "Piecewise-terminated spherical topological insulator as a virtual\n  breadboard for Majorana circuitry: We consider the surface states of a spherical topological insulator\npiecewise-terminated by superconductivity or ferromagnetism over various\nregions of the spherical surface. Such terminations gap the surface states by\nbreaking U(1) particle-number symmetry or time-reversal symmetry, respectively.\nInterfaces and trijunctions between differently terminated surface regions can\nhost propagating and bound Majorana modes, and the finite size of the spherical\nsystem makes it easily amenable to numerical analysis via exact diagonalization\nof the Bogoliubov-de Gennes Hamiltonian within a truncated Hilbert space.\nCreative termination patterning therefore allows one to prototype a variety of\nMajorana circuits, calculating energy spectra and plotting eigenfunctions over\nthe spherical surface. We develop the computational framework for this\napproach, establishing a virtual breadboard for Majorana circuitry, and apply\nit to circuits of interest, including the Majorana analog of a Mach-Zehnder\ninterferometer."
    },
    {
        "anchor": "Spin Injection from Ferromagnetic Metals into Gallium Nitride: The injection of spin polarized electrons from ferromagnetic metals (Fe and\nCo) into gallium nitride (GaN) via scanning tunneling microscopy (STM) is\ndemonstrated. Electrons from STM tips are injected into the semiconductor. Net\ncircular polarization of the emitted light is observed, which changes sign on\nreversal of the magnetization of the tip. The polarization is found to be in\nqualitative agreement with that expected from considerations based on the\nsplitting of the valence bands due to spin-orbit coupling and the crystal field\nsplitting corresponding to the wurtzite structure, and the magnitude of the\nspin polarization from the ferromagnetic metal. We find a lower bound for the\nspin injection efficiency of 25%, corresponding to a net spin polarization in\nthe semiconductor of 10%. This is the largest reported value for a room\ntemperature measurement of spin injection into semiconductors in air.",
        "positive": "Observation of boundary induced chiral anomaly bulk states and their\n  transport properties: The robust transport of edge modes is perhaps the most useful property of\ntopological materials. The existence of edge modes is guaranteed by the\nbulk-edge correspondence, which states that the number of topological edge\nmodes is determined by the bulk topological invariants. To obtain robust\ntransport on the edge, we need to make volumetric changes to many bulk atoms to\ncontrol the properties of a few edge atoms in a lower dimension. We suggest\nhere that we can do the reverse in some cases: the properties of the edge can\nguarantee chiral transport phenomena in some bulk modes, achieving phenomena\nthat are essentially the same as those observed in topological valley-Hall\nsystems. Specifically, we show that a topologically trivial 2D hexagonal\nphononic crystal slab (waveguide) bounded by hardwall boundaries guarantees the\nexistence of bulk modes with chiral anomaly inside a pseudogap. We\nexperimentally observed robust valley-selected transport, complete valley state\nconversion, and valley focusing of the chiral anomaly bulk states (CABSs) in\nsuch phononic crystal waveguides."
    },
    {
        "anchor": "Adiabatic quantization of Andreev levels: We identify the time $T$ between Andreev reflections as a classical adiabatic\ninvariant in a ballistic chaotic cavity (Lyapunov exponent $\\lambda$), coupled\nto a superconductor by an $N$-mode point contact. Quantization of the\nadiabatically invariant torus in phase space gives a discrete set of periods\n$T_{n}$, which in turn generate a ladder of excited states\n$\\epsilon_{nm}=(m+1/2)\\pi\\hbar/T_{n}$. The largest quantized period is the\nEhrenfest time $T_{0}=\\lambda^{-1}\\ln N$. Projection of the invariant torus\nonto the coordinate plane shows that the wave functions inside the cavity are\nsqueezed to a transverse dimension $W/\\sqrt{N}$, much below the width $W$ of\nthe point contact.",
        "positive": "Dimer Coupling Energies of the Si(001) Surface: The coupling energies between the buckled dimers of the Si(001) surface were\ndetermined through analysis of the anisotropic critical behavior of its\norder-disorder phase transition. Spot profiles in high-resolution low-energy\nelectron diffraction as a function of temperature were analyzed within the\nframework of the anisotropic two-dimensional Ising model. The validity of this\napproach is justified by the large ratio of correlation lengths,\n$\\xi_\\parallel^+/\\xi_\\perp^+ = 5.2$ of the fluctuating $c(4 {\\times} 2)$\ndomains above the critical temperature $T_\\mathrm{c} = (190.6 \\pm 10)$ K. We\nobtain effective couplings $J_\\parallel = (-24.9 \\pm 1.3)$ meV along the dimer\nrows and $J_\\perp = (-0.8 \\pm 0.1)$ meV across the dimer rows, i.e.,\nantiferromagnetic-like coupling of the dimers with $c(4 {\\times} 2)$ symmetry."
    },
    {
        "anchor": "Effective Dresselhaus and Rashba spin-orbit interactions in narrow\n  quantum wells: Rashba and linear Dresselhaus interactions are believed to yield dominant\ncontribution to the spin splitting of two-dimensional electrons in the quantum\nwells based on A$_3$B$_5$ compounds. We show that the interfacial spin-orbit\ninteraction significantly renormalizes the value of the corresponding Rashba\n($\\alpha_{SIA}$) and Dresselhaus ($\\alpha_{BIA}$) parameters. For this purpose,\nwe solve the effective mass equation in a quantum well supplemented by the\noriginal boundary conditions on the atomically sharp interfaces and calculate\nthe interfacial contributions to $\\alpha_{SIA}$ and $\\alpha_{BIA}$. Our results\nexplain a considerable spread in the experimental data on spin-orbit parameters\nin GaAs/AlGaAs quantum wells. We also demonstrated that the non-equivalence of\nthe interfaces leads to the anisotropy of the spin splitting even in quantum\nwells with zero average electric field.",
        "positive": "Tailoring Exciton Dynamics in TMDC Heterobilayers in the Quantum\n  Plasmonic Regime: Control of excitons in transition metal dichalcogenides (TMDCs) and their\nheterostructures is fundamentally interesting for tailoring light-matter\ninteractions and exploring their potential applications in high-efficiency\noptoelectronic and nonlinear photonic devices. While both intra- and interlayer\nexcitons in TMDCs have been heavily studied, their behavior in the quantum\ntunneling regime, in which the TMDC or its heterostructure is optically excited\nand concurrently serves as a tunnel junction barrier, remains unexplored. Here,\nusing the degree of freedom of a metallic probe in an atomic force microscope,\nwe investigated both intralayer and interlayer excitons dynamics in TMDC\nheterobilayers via locally controlled junction current in a finely tuned\nsub-nanometer tip-sample cavity. Our tip-enhanced photoluminescence\nmeasurements reveal a significantly different exciton-quantum plasmon coupling\nfor intralayer and interlayer excitons due to different orientation of the\ndipoles of the respective e-h pairs. Using a steady-state rate equation fit, we\nextracted field gradients, radiative and nonradiative relaxation rates for\nexcitons in the quantum tunneling regime with and without junction current. Our\nresults show that tip-induced radiative (nonradiative) relaxation of intralayer\n(interlayer) excitons becomes dominant in the quantum tunneling regime due to\nthe Purcell effect. These findings have important implications for near-field\nprobing of excitonic materials in the strong-coupling regime."
    },
    {
        "anchor": "Semiclassical theory of current correlations in chaotic\n  dot-superconductor systems: We present a semiclassical theory of current correlations in multiterminal\nchaotic dot-superconductor junctions, valid in the absence of the proximity\neffect in the dot. For a dominating coupling of the dot to the normal terminals\nand a nonperfect dot-superconductor interface, positive cross correlations are\nfound between currents in the normal terminals. This demonstrates that positive\ncross correlations can be described within a semiclassical approach. We show\nthat the semiclassical approach is equivalent to a quantum mechanical Green's\nfunction approach with suppressed proximity effect in the dot.",
        "positive": "Statistical Ensembles and Spectral Correlations in Mesoscopic Systems: Employing different statistical ensembles may lead to qualitatively different\nresults concerning averages of physical observables on the mesoscopic scale.\nHere we discuss differences between the canonical and the grandcanonical\nensembles due to both quenched disorder and thermodynamical effects. We show\nhow these differences are related to spectral correlations of the system at\nhand, and evaluate the conditions (temperature, system's size) when the\nthermodynamic limit is achieved. We demonstrate our approach by evaluating the\nheat capacity, persistent currents and the occupation probability of single\nelectron states, employing a systematic diagrammatic approach."
    },
    {
        "anchor": "Dual current anomalies and quantum transport within extended reservoir\n  simulations: Quantum transport simulations are rapidly evolving and now encompass\nwell-controlled tensor network techniques for many-body limits. One powerful\napproach combines matrix product states with extended reservoirs. In this\nmethod, continuous reservoirs are represented by explicit, discretized\ncounterparts and a chemical potential or temperature drop is maintained by\nexternal relaxation. Currents are strongly influenced by relaxation when it is\nvery weak or strong, resulting in a simulation analog of Kramers' turnover for\nsolution-phase chemical reactions. At intermediate relaxation, the intrinsic\nconductance, that given by the Landauer or Meir-Wingreen expressions, moderates\nthe current. We demonstrate that strong impurity scattering (i.e., a small\nsteady-state current) reveals anomalous transport regimes within this\nmethodology at weak-to-moderate and moderate-to-strong relaxation. The former\nis due to virtual transitions and the latter to unphysical broadening of the\npopulated density of states. Thus, the turnover analog has $five$ standard\ntransport regimes, further constraining the parameters that lead to recovery of\nthe intrinsic conductance. In the worst case, the common strategy of choosing a\nrelaxation strength proportional to the reservoir level spacing can prevent\nconvergence to the continuum limit. This advocates a simulation strategy where\none utilizes the current versus relaxation turnover profiles to identify\nsimulation parameters that most efficiently reproduce the intrinsic physical\nbehavior.",
        "positive": "Competition between fractional quantum Hall liquid and Wigner solid at\n  small fillings: Role of layer thickness and Landau level mixing: What is the fate of the ground state of a two-dimensional electron system\n(2DES) at very low Landau level filling factors ($\\nu$) where interaction\nreigns supreme? An ordered array of electrons, the so-called Wigner crystal,\nhas long been believed to be the answer. It was in fact the search for the\nelusive Wigner crystal that led to the discovery of an unexpected,\nincompressible liquid state, namely the fractional quantum Hall state at\n$\\nu=1/3$. Understanding the competition between the liquid and solid ground\nstates has since remained an active field of fundamental research. Here we\nreport experimental data for a new two-dimensional system where the electrons\nare confined to an AlAs quantum well. The exceptionally high quality of the\nsamples and the large electron effective mass allow us to determine the\nliquid-solid phase diagram for the two-dimensional electrons in a large range\nof filling factors near $\\simeq 1/3$ and $\\simeq 1/5$. The data and their\ncomparison with an available theoretical phase diagram reveal the crucial role\nof Landau level mixing and finite electron layer thickness in determining the\nprevailing ground states."
    },
    {
        "anchor": "The invisible Majorana bound state at the helical edge: The presence of a Majorana bound state in condensed matter systems is often\nassociated to a zero bias peak in conductance measurements. Here, we analyze a\nsystem were this paradigm is violated. A Majorana bound state is always present\nat the interface between a quantum spin Hall system that is magnetically gapped\nand a quantum spin Hall system gapped by proximity induced s-wave\nsuperconductivity. However, the linear conductance could be either zero or\nnonzero and quantized depending on the energy and length scales of the\nbarriers. The transition between the two values is reminiscent of the\ntopological phase transition in proximitized spin-orbit coupled quantum wires\nin the presence of an applied magnetic field. We interpret the behavior of the\nconductance in terms of scattering states at both zero and non-zero energy.",
        "positive": "Noise and Transport Characterization of Single Molecular Break Junctions\n  with Individual Molecule: We studied the noise spectra of molecule-free and molecule-containing\nmechanically controllable break junctions. Both types of junctions revealed\ntypical 1/ f noise characteristics at different distances between the contacts\nwith square dependence of current noise power spectral density on current.\nAdditional Lorentzian-shape (1/ f 2) noise components were recorded only when\nnanoelectrodes were bridged by individual 1,4 benzenediamine molecule. The\ncharacteristic frequency of the revealed 1/ f 2 noise related to a single\nbridging molecule correlates with the lock-in current amplitudes. The recorded\nbehavior of Lorentzian-shape noise component as a function of current is\ninterpreted as the manifestation of a dynamic reconfiguration of molecular\ncoupling to the metal electrodes. We propose a phenomenological model that\ncorrelates the charge transport via a single molecule with the reconfiguration\nof its coupling to the metal electrodes. Experimentally obtained results are in\ngood agreement with theoretical ones and indicate that coupling between the\nmolecule metal electrodes is important aspect that should be taken into\naccount."
    },
    {
        "anchor": "A theoretical investigation on the carrier mobilities of armchair\n  silicene nanoribbons: Armchair silicene nanoribbons with width of 9-39 silicon atoms are\ninvestigated by using self-consistent field crystal orbital method based on\ndensity functional theory. The carrier mobilities obtained from deformation\npotential theory oscillate with respect to the width and the values are a\nfraction of what the graphene nanoribbons have. The buckled structure, hydrogen\nsaturation, edge reconstruction as well as edge roughness decrease the carrier\nmobilities which are explained with the aid of crystal orbitals.",
        "positive": "Mesoscopic conductance fluctuations in graphene: We study fluctuations of the conductance of micron-sized graphene devices as\na function of the Fermi energy and magnetic field. The fluctuations are studied\nin combination with analysis of weak localization which is determined by the\nsame scattering mechanisms. It is shown that the variance of conductance\nfluctuations depends not only on inelastic scattering that controls dephasing\nbut also on elastic scattering. In particular, contrary to its effect on weak\nlocalization, strong intervalley scattering suppresses conductance fluctuations\nin graphene. The correlation energy, however, is independent of the details of\nelastic scattering and can be used to determine the electron temperature of\ngraphene structures."
    },
    {
        "anchor": "Impact of graphene on the polarizability of a neighbour nanoparticle: a\n  dyadic Green's function study: We discuss the renormalization of the polarizability of a nanoparticle in the\npresence of either (i) a continuous graphene sheet or (ii) a plasmonic graphene\ngrating, taking into account retardation effects. Our analysis demonstrates\nthat the excitation of surface plasmon-polaritons in graphene produces a large\nenhancement of the real and imaginary parts of the renormalized polarizability.\nWe show that the imaginary part can be changed by a factor of up to 100\nrelatively to its value in the absence of graphene. We also show that the\nresonance in the case of the grating is narrower than in the continuous sheet.\nIn the case of the grating it is shown that the resonance can be tuned by\nchanging the grating geometric parameters.",
        "positive": "Anomalous Hall effect in 2D Rashba ferromagnet: Skew scattering on rare impurity configurations is shown to dominate the\nanomalous Hall effect in a 2D Rashba ferromagnet. The mechanism originates in\nscattering on rare impurity pairs separated by distances of the order of the\nFermi wave length. Corresponding theoretical description goes beyond the\nconventional non-crossing approximation. The mechanism provides the only\ncontribution to the anomalous Hall conductivity in the most relevant metallic\nregime and strongly modifies previously obtained results for lower energies in\nthe leading order with respect to impurity strength."
    },
    {
        "anchor": "Effect of Edge Roughness on resistance and switching voltage of Magnetic\n  Tunnel Junctions: We investigate the impact of edge roughness on the electrical transport\nproperties of magnetic tunnel junctions using non-equilibrium Greens function\nformalism. We have modeled edge roughness as a stochastic variation in the\ncross-sectional profile of magnetic tunnel junction characterized by the\nstretched exponential decay of the correlation function. The stochastic\nvariation in the shape and size changes the transverse energy mode profile and\ngives rise to the variations in the resistance and switching voltage of the\nmagnetic tunnel junction. We find that the variations are larger as the\nmagnetic tunnel junction size is scaled down due to the quantum confinement\neffect. A model is proposed for the efficient calculation of edge roughness\neffects by approximating the cross-sectional geometry to a circle with the same\ncross-sectional area. Further improvement can be obtained by approximating the\ncross-sectional area to an ellipse with an aspect ratio determined by the first\ntransverse eigenvalue corresponding to the 2D cross section. These results\nwould be useful for reliable design of the spin transfer torque-magnetic random\naccess memory (STT-MRAM) with ultra-small magnetic tunnel junctions.",
        "positive": "Suppressed absolute negative conductance and generation of\n  high-frequency radiation in semiconductor superlattices: We show that space-charge instabilities (electric field domains) in\nsemiconductor superlattices are the attribute of absolute negative conductance\ninduced by small constant and large alternating electric fields. We propose the\nefficient method for suppression of this destructive phenomenon in order to\nobtain a generation at microwave and THz frequencies in devices operating at\nroom temperature. We theoretically proved that an unbiased superlattice with a\nmoderate doping subjected to a microwave pump field provides a strong gain at\nthird, fifth, seventh, etc. harmonics of the pump frequency in the conditions\nof suppressed domains."
    },
    {
        "anchor": "Investigating Atomic Contrast in Atomic Force Microscopy and Kelvin\n  Probe Force Microscopy on Ionic Systems using Functionalized Tips: Noncontact atomic force microscopy (NC-AFM) and Kelvin probe force microscopy\n(KPFM) have become important tools for nanotechnology; however, their contrast\nmechanisms on the atomic scale are not entirely understood. Here we used\nchlorine vacancies in NaCl bilayers on Cu(111) as a model system to investigate\natomic contrast as a function of applied voltage, tip height, and tip\nfunctionalization. We demonstrate that the AFM contrast on the atomic scale\ndecisively depends on both the tip termination and the sample voltage. On the\ncontrary, the local contact potential difference (LCPD) acquired with KPFM\nshowed the same qualitative contrast for all tip terminations investigated,\nwhich resembled the contrast of the electric field of the sample. We find that\nthe AFM contrast stems mainly from electrostatic interactions but its tip\ndependence cannot be explained by the tip dipole alone. With the aid of a\nsimple electrostatic model and by density functional theory we investigate the\nunderlying contrast mechanisms.",
        "positive": "Metal insulator transition in modulated quantum Hall systems: The quantum Hall effect is studied numerically in modulated two-dimensional\nelectron systems in the presence of disorder. Based on the scaling property of\nthe Hall conductivity as well as the localization length, the critical energies\nwhere the states are extended are identified. We find that the critical\nenergies, which are distributed to each of the subbands, combine into one when\nthe disorder becomes strong, in the way depending on the symmetry of the\ndisorder and/or the periodic potential."
    },
    {
        "anchor": "Two-dimensional Dirac fermions in a mass superlattice: We study two-dimensional (2D) Dirac fermions in the presence of a periodic\nmass term alternating between positive and negative values along one direction.\nThis scenario could be realized for a graphene monolayer or for the surface\nstates of topological insulators. The low-energy physics is governed by chiral\nJackiw-Rebbi modes propagating along zero-mass lines, with the energy\ndispersion of the Bloch states given by an anisotropic Dirac cone. By means of\nthe transfer matrix approach, we obtain exact results for a piece-wise constant\nmass superlattice. On top of Bloch states, two different classes of boundary\nand/or interface modes can exist in a finite-size geometry or in a nonuniform\nelectrostatic potential, respectively. We compute the dispersion relation for\nboth types of boundary and interface modes, which originate either from states\nclose to the superlattice Brillouin zone (BZ) center or, via a Lifshitz\ntransition, from states near the BZ boundary. In the presence of a potential\nstep, we predict that the interface modes, the Bloch wave functions, and the\nelectrical conductance will sensitively depend on the step position relative to\nthe mass superlattice.",
        "positive": "Semiclassical Dynamics and Nonlinear Charge Current: Electron conductivity is an important material property that can provide a\nwealth of information about the underlying system. Especially, the response of\nthe conductivity with respect to electromagnetic fields corresponds to various\nnonlinear charge currents, which have distinct symmetry requirements and hence\ncan be used as efficient probes of different systems. To help the\nband-structure engineering of such nonlinear currents, a universal treatment of\nelectron dynamics up to second order expressed in the basis of the unperturbed\nstates are highly useful. In this work, we review the general semiclassical\nframework of the nonlinear charge currents."
    },
    {
        "anchor": "Two-laser dynamic nuclear polarization with semiconductor electrons:\n  feedback, suppressed fluctuations, and bistability near two-photon resonance: We present how optical coherent population trapping (CPT) of the spin of\nlocalized semiconductor electrons stabilizes the surrounding nuclear spin bath\nvia the hyperfine interaction, resulting in a state which is more ordered than\nthe thermal equilibrium state. We find distinct control regimes for different\nsigns of laser detuning and examine the transition from an unpolarized,\nnarrowed state to a polarized state possessing a bistability. The narrowing of\nthe state yields slower electron spin dephasing and self-improving CPT. Our\nanalysis is relevant for a variety of solid state systems where\nhyperfine-induced dephasing is a limitation for using electron spin coherence.",
        "positive": "High mobility two-dimensional hole system on hydrogen-terminated silicon\n  (111) surfaces: We have realized a two-dimensional hole system (2DHS), in which the 2DHS is\ninduced at an atomically flat hydrogen-terminated Si(111) surface by a negative\ngate voltage applied across a vacuum cavity. Hole densities up to\n$7.5\\times10^{11}$ cm$^{-2}$ are obtained, and the peak hole mobility is about\n$10^4$ cm$^2$/Vs at 70 mK. The quantum Hall effect is observed. Shubnikov-de\nHaas oscillations show a beating pattern due to the spin-orbit effects, and the\ninferred zero-field spin splitting can be tuned by the gate voltage."
    },
    {
        "anchor": "Quantum interference in a macroscopic van der Waals conductor: Quantum corrections to charge transport can give rise to an oscillatory\nmagnetoconductance, typically observed in mesoscopic samples with a length\nshorter than or comparable with the phase coherence length. Here, we report the\nobservation of magnetoconductance oscillations periodic in magnetic field with\nan amplitude of the order of $e^2/h$ in macroscopic samples of Highly Oriented\nPyrolytic Graphite (HOPG). The observed effect emerges when all carriers are\nconfined to their lowest Landau levels. We argue that this quantum interference\nphenomenon can be explained by invoking moir\\'e superlattices with a discrete\ndistribution in periodicity. According to our results, when the magnetic length\n$\\ell_B$, the Fermi wave length $\\lambda_F$ and the length scale of\nfluctuations in local chemical potential are comparable in a layered conductor,\nquantum corrections can be detected over centimetric length scales.",
        "positive": "Metallic behavior in Si/SiGe 2D electron systems: We calculate the temperature, density, and parallel magnetic field dependence\nof low temperature electronic resistivity in 2D high-mobility Si/SiGe quantum\nstructures, assuming the conductivity limiting mechanism to be carrier\nscattering by screened random charged Coulombic impurity centers. We obtain\ncomprehensive agreement with existing experimental transport data, compellingly\nestablishing that the observed 2D metallic behavior in low-density Si/SiGe\nsystems arises from the peculiar nature of 2D screening of long-range impurity\ndisorder. In particular, our theory correctly predicts the experimentally\nobserved metallic temperature dependence of 2D resistivity in the fully\nspin-polarized system."
    },
    {
        "anchor": "Topological Properties of Adiabatically Varied Floquet Systems: Energy or quasienergy (QE) band spectra depending on two parameters may have\na nontrivial topological characterization by Chern integers. Band spectra of 1D\nsystems that are spanned by just one parameter, a Bloch phase, are\ntopologically trivial. Recently, an ensemble of 1D Floquet systems, double\nkicked rotors (DKRs) depending on an external parameter, has been studied. It\nwas shown that a QE band spanned by both the Bloch phase and the external\nparameter is characterized by a Chern integer, which determines the change in\nthe mean angular momentum of a state in a band when the external parameter is\nadiabatically varied by a natural period. We show here, under conditions much\nmore general than in previous works, that the ensemble of DKRs for all values\nof the external parameter is fully described by a system having translational\ninvariance on the phase plane. This system can be characterized by a\n\\emph{second} Chern integer which is shown to be connected with the integer\nabove for the DKR ensemble. This connection is expressed by a Diophantine\nequation (DE) which we derive. The DE, involving the number of QE bands and the\ndegeneracy of the QE states of the phase-plane system, limits the values of the\nDKR-ensemble integer. In particular, this integer is generically nonzero,\nshowing the general topological nontriviality of the DKR ensemble.",
        "positive": "Canted Spin Texture and Quantum Spin Hall Effect in WTe2: We report an unconventional quantum spin Hall phase in the monolayer\nT$_\\text{d}$-WTe$_2$, which exhibits hitherto unknown features in other\ntopological materials. The low-symmetry of the structure induces a canted spin\ntexture in the $yz$ plane, which dictates the spin polarization of\ntopologically protected boundary states. Additionally, the spin Hall\nconductivity gets quantized ($2e^2/h$) with a spin quantization axis parallel\nto the canting direction.\n  These findings are based on large-scale quantum simulations of the spin Hall\nconductivity tensor and nonlocal resistances in multi-probe geometries using a\nrealistic tight-binding model elaborated from first-principle methods.\n  The observation of this canted quantum spin Hall effect, related to the\nformation of topological edge states with nontrivial spin polarization, demands\nfor specific experimental design and suggests interesting alternatives for\nmanipulating spin information in topological materials."
    },
    {
        "anchor": "Charge correlations in polaron hopping through molecules: In many organic molecules the strong coupling of excess charges to\nvibrational modes leads to the formation of polarons, i.e., a localized state\nof a charge carrier and a molecular deformation. Incoherent hopping of polarons\nalong the molecule is the dominant mechanism of transport at room temperature.\nWe study the far-from-equilibrium situation where, due to the applied bias, the\ninduced number of charge carriers on the molecule is high enough such that\ncharge correlations become relevant. We develop a diagrammatic theory that\nexactly accounts for all many-particle correlations functions for incoherent\ntransport through a finite system. We compute the transport properties of short\nsequences of DNA by expanding the diagrammatic theory up to second order in the\nhopping parameters. The correlations qualitatively modify the I-V\ncharacteristics as compared to those approaches where correlations are dealt\nwith in a mean-field type approximation only.",
        "positive": "Electrical domain writing and nanoscale potential modulation on\n  LaVO$_3$/SrTiO$_3$: The high-mobility 2DEGs formed at the interfaces between certain insulating\nperovskite oxides have been known to be a novel playground of exotic physical\norders like, superconductivity and ferromagnetism and their inter-coupling.\nThere have been efforts to accomplish even more exotic properties at such\ninterfaces of oxide heterostructures through nano-structuring of the surface.\nIn this paper we report writing and erasing charge domains on such an oxide\nheterostructure LaVO$_3$/SrTiO$_3$ using a conductive AFM cantilever. We have\npatterned these domains in a periodic fashion in order to create artificial\nlattices on the surface. Through kelvin probe microscopy, electrostatic force\nmicroscopy and conductivity mapping of such artificial lattices we found that\nthe domains not only trap charge carriers but also develop a controllable\npotential landscape on the surface which coincides with a modulation of local\nelectrical conductivity. The ability to pattern such nanostructures reversibly\noffers unprecedented opportunities of realizing ultra-high storage density\ndevices in high mobility oxide heterostructures."
    },
    {
        "anchor": "Multi-orbital Non-Crossing Approximation from maximally localized\n  Wannier functions: the Kondo signature of copper phthalocyanine on Ag (100): We have developed a multi-orbital approach to compute the electronic\nstructure of a quantum impurity using the non-crossing approximation. The\ncalculation starts with a mean-field evaluation of the system's electronic\nstructure using a standard quantum chemistry code. Here we use density\nfunctional theory (DFT). We transformed the one-electron structure into an\nimpurity Hamiltonian by using maximally localized Wannier functions (MLWF).\nHence, we have developed a method to study the Kondo effect in systems based on\nan initial one-electron calculation. We have applied our methodology to a\ncopper phthalocyanine molecule chemisorbed on Ag (100), and we have described\nits spectral function for three different cases where the molecule presents a\nsingle spin or two spins with ferro- and anti-ferromagnetic exchange couplings.\nWe find that the use of broken-symmetry mean-field theories such as Kohn-Sham\nDFT cannot deal with the complexity of the spin of open-shell molecules on\nmetal surfaces and extra modeling is needed.",
        "positive": "Quantum Nonlinear Optics in Atomically Thin Materials: We show that a nonlinear optical response associated with a resonant,\natomically thin material can be dramatically enhanced by placing it in front of\na partially reflecting mirror, rendering otherwise weakly nonlinear systems\nsuitable for experiments and applications involving quantum nonlinear optics.\nOur approach exploits the nonlinear response of long-lived polariton resonances\nthat arise at particular distances between the material and the mirror. The\nscheme is entirely based on free-space optics, eliminating the need for\ncavities or complex nanophotonic structures. We analyze a specific\nimplementation based on exciton-polariton resonances in two-dimensional\nsemiconductors and discuss the role of imperfections and loss."
    },
    {
        "anchor": "Tight-binding dispersion of the prismatic pentagonal lattice: Tight-binding Hamiltonian on the prismatic pentagonal lattice is exactly\nsolved to obtain the analytic expressions of dispersion relations and\neigenvectors. This lattice is made of prismatic pentagon which is different\nfrom Cairo pentagon. Six different dispersion relations and total density of\nstates are obtained. Dispersion relations are symmetric about the zero energy\nat a particular point in the parameter space. Although a large gap is found for\nthe Cairo pentagonal lattice, no gap as well as no Dirac cone is found to\nappear in the tight-binding band structure for this prismatic pentagonal\nlattice. Instead, a pair of van Hove singularities has been identified at two\ndifferent energy values in the band structure.",
        "positive": "Electron-electron interactions in a one-dimensional quantum wire spin\n  filter: The combined presence of a Rashba and a Zeeman effect in a ballistic\none-dimensional conductor generates a spin pseudogap and the possibility to\npropagate a beam with well defined spin orientation. Without interactions\ntransmission through a barrier gives a relatively well polarized beam. Using\nrenormalization group arguments, we examine how electron-electron interactions\nmay affect the transmission coefficient and the polarization of the outgoing\nbeam."
    },
    {
        "anchor": "Aharonov-Casher Effect in Wigner Crystal Exchange Interactions: We theoretically study the effects of spin-orbit coupling on spin exchange in\na low-density Wigner crystal. In addition to the familiar antiferromagnetic\nHeisenberg exchange, we find general anisotropic interactions in spin space if\nthe exchange paths allowed by the crystal structure form loops in real space.\nIn particular, it is shown that the two-electron exchange interaction can\nacquire ferromagnetic character.",
        "positive": "Josephson Diode Effect in Andreev Molecules: We propose a new platform for observing the Josephson diode effect: the\nAndreev molecule. This nonlocal electronic state is hosted in circuits made of\ntwo closely spaced Josephson junctions, through the hybridization of the\nAndreev states. The Josephson diode effect occurs at the level of one\nindividual junction while the other one generates the required time-reversal\nand spatial-inversion symmetry breaking. We present a microscopic description\nof this phenomenon based on fermionic Andreev states, focusing on single\nchannels in the short limit, and we compute both supercurrent and energy\nspectra. We demonstrate that the diode efficiency can be tuned by magnetic flux\nand the junctions transmissions, and can reach $45~\\%$. Going further, by\nanalyzing the Andreev spectra, we demonstrate the key role played by the\ncontinuum, which consists of leaky Andreev states and is largely responsible\nfor the critical current asymmetry. On top of proposing an experimentally\naccessible platform, this work elucidates the microscopic origin of the\nJosephson diode effect at the level of the fermionic Andreev states."
    },
    {
        "anchor": "Transport through molecular junctions with a nonequilibrium phonon\n  population: The calculation of the nonlinear conductance of a single-molecule junction is\nrevisited. The self energy on the junction resulting from the electron-phonon\ninteraction has at low temperatures logarithmic singularities (in the real\npart) and discontinuities (in the imaginary one) at the frequencies\ncorresponding to the opening of the inelastic channels. These singularities\ngenerate discontinuities and logarithmic divergences (as a function of the bias\nvoltage) in the low-temperature differential conductance around the inelastic\nthresholds. The self energy also depends on the population of the vibrational\nmodes. The case of a vibrating free junction (not coupled to a thermal bath),\nwhere the phonon population is determined by the bias voltage is examined. We\ncompare the resulting zero-temperature differential conductance with the one\nobtained for equilibrated phonons, and find that the difference is larger the\nlarger is the bare transmission of the junction and the product of the electron\ndwell time on the junction with the phonon frequency.",
        "positive": "Selective damping of plasmons in coupled two-dimensional systems by\n  Coulomb drag: The Coulomb drag is a many-body effect observed in proximized low-dimensional\nsystems. It appears as emergence of voltage in one of them upon passage of bias\ncurrent in another. The magnitude of drag voltage can be strongly affected by\nexchange of plasmonic excitations between the layers; however, the reverse\neffect of Coulomb drag on properties of plasmons has not been studied. Here, we\nstudy the plasmon spectra and damping in parallel two-dimensional systems in\nthe presence of Coulomb drag. We find that Coulomb drag leads to selective\ndamping of one of the two fundamental plasma modes of a coupled bilayer. For\nidentical electron doping of both layers, the drag suppresses the acoustic\nplasma mode; while for symmetric electron-hole doping of the coupled pair, the\ndrag suppresses the optical plasma mode. The selective damping can be observed\nboth for propagating modes in extended bilayers and for localized plasmons in\nbilayers confined by source and drain contacts. The discussed effect may\nprovide access to the strength of Coulomb interaction in 2d electron systems\nfrom various optical and microwave scattering experiments."
    },
    {
        "anchor": "Quantum Hall Effect in Bilayer Graphene: Disorder Effect and Quantum\n  Phase Transition: We numerically study the quantum Hall effect (QHE) in bilayer graphene based\non tight-binding model in the presence of disorder. Two distinct QHE regimes\nare identified in the full energy band separated by a critical region with\nnon-quantized Hall Effect. The Hall conductivity around the band center (Dirac\npoint) shows an anomalous quantization proportional to the valley degeneracy,\nbut the $\\nu=0$ plateau is markedly absent, which is in agreement with\nexperimental observation. In the presence of disorder, the Hall plateaus can be\ndestroyed through the float-up of extended levels toward the band center and\nhigher plateaus disappear first. The central two plateaus around the band\ncenter are most robust against disorder scattering, which is separated by a\nsmall critical region in between near the Dirac point. The longitudinal\nconductance around the Dirac point is shown to be nearly a constant in a range\nof disorder strength, till the last two QHE plateaus completely collapse.",
        "positive": "The role of the band gaps in reconstruction of polar surfaces and\n  interfaces: Density functional theory applied to a simple ionic material, MgO, is used as\na model system to clarify several aspects of electronic driven mechanism to\ncompensate for the diverging electrostatic potential in the polar structures.\nWe demonstrate that in the stoichiometric free standing films, the electronic\nreconstruction is limited by the band gap. This produces a residual electric\nfield in the bulk of the sample which is extremely sensitive to tiny deviations\nin electron transfer between two surfaces of the slab. In heterostructures, the\nband gap is replaced by a new effective energy scale set by the band alignment\nof its component. This changes the reconstruction pathways so that the\nelectronic mechanism can benefit from the smallest energy scale possible."
    },
    {
        "anchor": "The role of Coulomb interaction on the electronic properties of\n  monolayer NiX$_2$ (X = S, Se): A DFT+U+V study: The electronic structure of Nickel dichalcogenides, NiS$_2$ and NiSe$_2$, in\nmonolayer form, is studied employing first-principles methods. We assess the\nimportance of band ordering, covalency and Coulomb interactions in the ground\nstate of these systems. Hybrid functional results are compared with standard\nfunctionals and also with Hubbard-corrected functionals to systematically\naddress the role of electronic interactions and localization. We found that\nmean-field correlation realized by intersite Hubbard interactions are directly\nlinked to the magnitude of the energy band gap, giving compelling evidence for\nthe presence of a charge transfer insulating phase in these materials.",
        "positive": "Coherent probing of excited quantum dot states in an interferometer: Measurements of elastic and inelastic cotunneling currents are presented on a\ntwo-terminal Aharonov--Bohm interferometer with a Coulomb blockaded quantum dot\nembedded in each arm. Coherent current contributions, even in magnetic field,\nare found in the nonlinear regime of inelastic cotunneling at finite bias\nvoltage. The phase of the Aharonov--Bohm oscillations in the current exhibits\nphase jumps of $\\pi$ at the onsets of inelastic processes. We suggest that\nadditional coherent elastic processes occur via the excited state. Our\nmeasurement technique allows the detection of such processes on a background of\nother inelastic current contributions and contains information about the\nexcited state occupation probability and the inelastic relaxation rates."
    },
    {
        "anchor": "Non-Abelian quantized Hall states of electrons at filling factors 12/5\n  and 13/5 in the first excited Landau level: We present results of extensive numerical calculations on the ground state of\nelectrons in the first excited (n=1) Landau level with Coulomb interactions,\nand including non-zero thickness effects, for filling factors 12/5 and 13/5 in\nthe torus geometry. In a region that includes these experimentally-relevant\nvalues, we find that the energy spectrum and the overlaps with the trial states\nsupport the previous hypothesis that the system is in the non-Abelian k = 3\nliquid phase we introduced in a previous paper.",
        "positive": "Ab initio GW electron-electron interaction effects in Quantum Transport: We present an ab initio approach to electronic transport in nanoscale systems\nwhich includes electronic correlations through the GW approximation. With\nrespect to Landauer approaches based on density-functional theory (DFT), we\nintroduce a physical quasiparticle electronic-structure into a non-equilibrium\nGreen's function theory framework. We use an equilibrium non-selfconsistent\n$G^0W^0$ self-energy considering both full non-hermiticity and dynamical\neffects. The method is applied to a real system, a gold mono-atomic chain. With\nrespect to DFT results, the conductance profile is modified and reduced by to\nthe introduction of diffusion and loss-of-coherence effects. The linear\nresponse conductance characteristic appear to be in agreement with experimental\nresults."
    },
    {
        "anchor": "A very low temperature STM for the local spectroscopy of mesoscopic\n  structures: We present the design and operation of a very-low temperature Scanning\nTunneling Microscope (STM) working at $60 mK$ in a dilution refrigerator. The\nSTM features both atomic resolution and micron-sized scanning range at low\ntemperature. This work is the first experimental realization of a local\nspectroscopy of mesoscopic structures at very low temperature. We present\nhigh-resolution current-voltage characteristics of tunnel contacts and the\ndeduced local density of states of hybrid Superconductor-Normal metal systems.",
        "positive": "Multiterminal Quantized Conductance in InSb Nanocrosses: By studying the time-dependent axial and radial growth of InSb nanowires, we\nmap the conditions for the synthesis of single-crystalline InSb nanocrosses by\nmolecular beam epitaxy. Low-temperature electrical measurements of InSb\nnanocross devices with local gate control on individual terminals exhibit\nquantized conductance and are used to probe the spatial distribution of the\nconducting channels. Tuning to a situation where the nanocross junction is\nconnected by few-channel quantum point contacts in the connecting nanowire\nterminals, we show that transport through the junction is ballistic except\nclose to pinch-off. Combined with a new concept for shadow-epitaxy of patterned\nsuperconductors on nanocrosses, the structures reported here show promise for\nthe realization of non-trivial topological states in multi-terminal Josephson\nJunctions."
    },
    {
        "anchor": "Electronic properties of graphyne-$N$ monolayer and its multilayer:\n  even-odd effect and topological nodal line semimetalic phases: We study the electronic structure and topological properties of monolayer and\nABC-stacked multilayer of graphyne-$N$, which are a family of planar carbon\nsheets consisting of $sp$ and $sp_2$-bonding. By using the density-functional\ntheory and the effective continuum model, we find a striking even-odd effect in\nthe dependence of the band structure on $N$ (the number of carbon-carbon triple\nbonds between neighboring benzene rings). Specifically, even-$N$ graphyne\nmonolayer has doubly-degenerate conduction and valence bands near the Fermi\nenergy, and in its ABC multilayer, the band inversion of the doubly-degenerate\nbands leads to a nodal-line semimetal phase with non-trivial $\\mathbb{Z}_2$\nmonopole charge. In contrast, odd-$N$ monolayer has singly-degenerate bands in\nseparate valleys, and its ABC multilayer can have only $\\mathbb{Z}_2$-trivial\nnodal lines. ABC graphynes with larger $N$ tend to be trivial insulators\nbecause of smaller interlayer coupling, while the external pressure induces a\ntopological phase transition from the trivial phase to the nodal line semimetal\nphase.",
        "positive": "Coexistence of New Fermions in Topological Semimetal TaS: We theoretically propose that, the single crystal formed TaS is a new type of\ntopological semimetal, hosting ring-shaped gapless nodal lines and triply\ndegenerate points (TDPs) in the absence of spin-orbit coupling (SOC). In the\npresence of SOC, the each TDP splits into four TDPs along the high symmetric\nline in the momentum space, and one of the nodal ring remains closed due to the\nprotection of the mirror reflection symmetry, while another nodal ring is fully\ngapped and transforms into six pairs ofWeyl points (WPs) carrying opposite\nchirality. The electronic structures of the projected surfaces are also\ndiscussed, the unique Fermi arcs are observed and the chirality remains or\nvanishes depending on the projection directions. On the (010) projected\nsurface, one may observe a Lifshitz transition. The new type of topological\nsemimetal TaS is stable and experimentally achievable, and the coexistence of\ntopological nodal lines, WPs and TDPs states in TaS makes it a potential\ncandidate to study the interplay between different types of topological\nfermions."
    },
    {
        "anchor": "Nano-imaging of the edge-dependent optical polarization anisotropy of\n  black phosphorus: The electronic structure and functionality of 2D materials is highly\nsensitive to structural morphology, opening the possibility for manipulating\nmaterial properties, but also making predictable and reproducible functionality\nchallenging. Black phosphorus (BP), a corrugated orthorhombic 2D material, has\nin-plane optical absorption anisotropy critical for applications such as\ndirectional photonics, plasmonics, and waveguides. Here, we use\npolarization-dependent photoemission electron microscopy to visualize the\nanisotropic optical absorption of BP with 54 nm spatial resolution. We find the\nedges of BP flakes have a shift in their optical polarization anisotropy from\nthe flake interior due to the 1D confinement and symmetry reduction at flake\nedges that alter the electronic charge distributions and transition dipole\nmoments of edge electronic states, confirmed with first-principles\ncalculations. These results uncover previously hidden modification of the\npolarization-dependent absorbance at the edges of BP, highlighting the\nopportunity for selective excitation of edge states of 2D materials with\npolarized light.",
        "positive": "Why graphene conductivity is constant: scaling theory consideration: In the recent paper [arXiv:0802.2216, 15 Feb 2008], Kashuba argued that the\nintrinsic conductivity of graphene independent of temperature originated in\nstrong electron-hole scattering. We propose a much more explicit derivation\nbased on a scaling theory approach. We also give an explanation of a rapid\nincrease in graphene conductivity caused by applied gate voltage."
    },
    {
        "anchor": "Topological quantum wires with balanced gain and loss: We study a one-dimensional topological superconductor, the Kitaev chain,\nunder the influence of a non-Hermitian but $\\mathcal{PT}$-symmetric potential.\nThis potential introduces gain and loss in the system in equal parts. We show\nthat the stability of the topological phase is influenced by the gain/loss\nstrength and explicitly derive the bulk topological invariant in a bipartite\nlattice as well as compute the corresponding phase diagram using analytical and\nnumerical methods. Furthermore we find that the edge state is exponentially\nlocalized near the ends of the wire despite the presence of gain and loss of\nprobability amplitude in that region.",
        "positive": "Easy-plane spin Hall oscillator: Spin Hall oscillators (SHOs) based on bilayers of a ferromagnet (FM) and a\nnon-magnetic heavy metal (HM) are electrically tunable nanoscale microwave\nsignal generators. Achieving high output power in SHOs requires driving\nlarge-amplitude magnetization dynamics by a direct spin Hall current. The\nmaximum possible amplitude of such oscillations with the precession cone angle\nnearing $90^\\circ$ is predicted for FM layers with easy-plane magnetic\nanisotropy and spin Hall current polarization perpendicular to the easy plane.\nWhile many FMs exhibit natural easy-plane anisotropy in the FM film plane, the\nspin Hall current in a HM|FM bilayer is polarized in this plane and thus cannot\ndrive large-amplitude magneto-dynamics. Here we present a new type of SHO\nengineered to have the easy-plane anisotropy oriented normal to the film plane,\nenabling large-amplitude easy-plane dynamics driven by spin Hall current. Our\nexperiments and micromagnetic simulations demonstrate that the desired\neasy-plane anisotropy can be achieved by tuning the magnetic shape anisotropy\nand perpendicular magnetic anisotropy in a nanowire SHO, leading to a\nsignificant enhancement of the generated microwave power. The easy-plane SHO\nexperimentally demonstrated here is an ideal candidate for realization of a\nspintronic spiking neuron. Our results provide a new approach to design of\nhigh-power SHOs for wireless communications, neuromorphic computing, and\nmicrowave assisted magnetic recording."
    },
    {
        "anchor": "Electron-hole collision-limited resistance of gapped graphene: Collisions between electrons and holes can dominate the carrier scattering in\nclean graphene samples in the vicinity of charge neutrality point. While\nelectron-hole limited resistance in pristine gapless graphene is well-studied,\nits evolution with induction of band gap $E_g$ is less explored. Here, we\nderive the functional dependence of electron-hole limited resistance of gapped\ngraphene $\\rho_{eh}$ on the ratio of gap and thermal energy $E_g/kT$. At low\ntemperatures and large band gaps, the resistance grows linearly with $E_g/kT$,\nand possesses a minimum at $E_g \\approx 2.5 kT$. This contrast to the Arrhenius\nactivation-type behaviour for intrinsic semiconductors. Introduction of\nimpurities restores the Arrhenius law for resistivity at low temperatures\nand/or high doping densities. The hallmark of electron-hole collision effects\nin graphene resistivity at charge neutrality is the crossover between\nexponential and power-law resistivity scalings with temperature.",
        "positive": "Modelling of planar germanium hole qubits in electric and magnetic\n  fields: Hole-based spin qubits in strained planar germanium quantum wells have\nreceived considerable attention due to their favourable properties and\nremarkable experimental progress. The sizeable spin-orbit interaction in this\nstructure allows for efficient electric qubit operations. However, it also\ncouples the qubit to electrical noise. In this work we perform simulations of a\nheterostructure hosting these hole spin qubits. We solve the effective mass\nequations for a realistic heterostructure, provide a set of analytical basis\nwave functions, and compute the effective g-factor of the heavy-hole\nground-state. Our investigations reveal a strong impact of highly excited light\nhole states located outside the quantum well on the g-factor. Consequently,\ncontrary to recent predictions, we find that sweet spots in out-of-plane\nmagnetic fields are shifted to impractically large electric fields. However,\nfor magnetic fields close to in-plane alignment, sweet spots at low electric\nfields are recovered. This work will be helpful in understanding and improving\ncoherence of germanium hole spin qubits."
    },
    {
        "anchor": "Tunneling spectroscopy of localized states of $\\mathrm{WS}_2$ barriers\n  in vertical van der Waals heterostructures: In transition metal dichalcogenides, defects have been found to play an\nimportant role, affecting doping, spin-valley relaxation dynamics, and\nassisting in proximity effects of spin-orbit coupling. Here, we study localized\nstates in $\\mathrm{WS}_2$ and how they affect tunneling through van der Waals\nheterostructures of h-BN/graphene/$\\mathrm{WS}_2$/metal. The obtained\nconductance maps as a function of bias and gate voltage reveal single-electron\ntransistor behavior (Coulomb blockade) with a rich set of transport features\nincluding excited states and negative differential resistance regimes. Applying\na perpendicular magnetic field, we observe a shift in the energies of the\nquantum levels and information about the orbital magnetic moment of the\nlocalized states is extracted.",
        "positive": "Tunneling broadening of vibrational sidebands in molecular transistors: Transport through molecular quantum dots coupled to a single vibration mode\nis studied in the case with strong coupling to the leads. We use an expansion\nin the correlation between electrons on the molecule and electrons in the leads\nand show that the tunneling broadening is strongly suppressed by the\ncombination of the Pauli principle and the quantization of the oscillator. As a\nconsequence the first Frank-Condon step is sharper than the higher order ones,\nand its width, when compared to the bare tunneling strength, is reduced by the\noverlap between the groundstates of the displaced and the non-displaced\noscillator."
    },
    {
        "anchor": "Anisotropic magnetoresistance in single electron transport: We study the effect of magnetic anisotropy in a single electron transistor\nwith ferromagnetic electrodes and a non-magnetic island. We identify the\nvariation $\\delta \\mu$ of the chemical potential of the electrodes as a\nfunction of the magnetization orientation as a key quantity that permits to\ntune the electrical properties of the device. Different effects occur depending\non the relative size of $\\delta \\mu$ and the charging energy. We provide\npreliminary quantitative estimates of $\\delta \\mu$ using a very simple toy\nmodel for the electrodes.",
        "positive": "Observation of exciton-exciton interaction mediated valley\n  depolarization in monolayer MoSe$_2$: The valley pseudospin in monolayer transition metal dichalcogenides (TMDs)\nhas been proposed as a new way to manipulate information in various\noptoelectronic devices. This relies on a large valley polarization that remains\nstable over long timescales (hundreds of ns). However, time resolved\nmeasurements report valley lifetimes of only a few ps. This has been attributed\nto mechanisms such as phonon-mediated inter-valley scattering and a precession\nof the valley psedospin through electron-hole exchange. Here we use transient\nspin grating to directly measure the valley depolarization lifetime in\nmonolayer MoSe$_{2}$. We find a fast valley decay rate that scales linearly\nwith the excitation density at different temperatures. This establishes the\npresence of strong exciton-exciton Coulomb exchange interactions enhancing the\nvalley depolarization. Our work highlights the microscopic processes inhibiting\nthe efficient use of the exciton valley pseudospin in monolayer TMDs."
    },
    {
        "anchor": "Non-Hermitian Avalanche Effect: Non-Perturbative Effect Induced by Local\n  Non-Hermitian Perturbation on a Z2 Topological Order: In this paper, based on a non-Hermitian toric-code model, we surprisingly\nfind that the degeneracy of ground states can be changed by a local\nnon-Hermitian perturbation (even in thermodynamic limit). We call it\nnon-Hermitian avalanche effect. As the physics consequences of the\nnon-Hermitian avalanche effect, a correspondence between bulk quasi-particles\nand topologically protected degenerate ground states for Z2 topological order\nis borken down. In addition, the PT symmetry breaking transition of the\ntopologically degenerate ground states subspace can be observed by fidelity\nsusceptibility.",
        "positive": "Theory on the scattering of light and surface plasmon polaritons by\n  arrays of holes and dimples in a metal film: The scattering of light and surface plasmon polaritons (SPPs) by finite\narrays of either holes or dimples in a metal film is treated theoretically. A\nmodal expansion formalism, capable of handling real metals with up to thousands\nof indentations, is presented. Computations based on this method demonstrate\nthat a single hole scatters a significant fraction of incoming light into SPPs.\nIt is also observed that holes and dimples scatter SPPs into light with similar\nefficiencies, provided the depth of the dimple is larger than its radius.\nFinally, it is shown that in arrays the normalized-to-area emittances in the\nout-of-plane and SPP channels present different dependences with the number of\nholes."
    },
    {
        "anchor": "Half quantum spin Hall effect on the surface of weak topological\n  insulators: We investigate interaction effects in three dimensional weak topological\ninsulators (TI) with an even number of Dirac cones on the surface. We find that\nthe surface states can be gapped by a surface charge density wave (CDW) order\nwithout breaking the time-reversal symmetry. In this sense, time reversal\nsymmetry alone can not robustly protect the weak TI state in the presence of\ninteractions. If the translational symmetry is additionally imposed in the\nbulk, a topologically non-trivial weak TI state can be obtained with helical\nedge states on the CDW domain walls. In other words, a CDW domain wall on the\nsurface is topologically equivalent to the edge of a two-dimensional quantum\nspin Hall insulator. Therefore, the surface state of a weak topological\ninsulator with translation symmetry breaking on the surface has a \"half quantum\nspin Hall effect\", in the same way that the surface state of a strong\ntopological insulator with time-reversal symmetry breaking on the surface has a\n\"half quantum Hall effect\". The on-site and nearest neighbor interactions are\ninvestigated in the mean field level and the phase diagram for the surface\nstates of weak topological insulators is obtained.",
        "positive": "Out-of-equilibrium singlet-triplet Kondo effect in a single C_60 quantum\n  dot: We have used an electromigration technique to fabricate a $\\rm{C_{{60}}}$\nsingle-molecule transistor (SMT). Besides describing our electromigration\nprocedure, we focus and present an experimental study of a single molecule\nquantum dot containing an even number of electrons, revealing, for two\ndifferent samples, a clear out-of-equilibrium Kondo effect. Low temperature\nmagneto-transport studies are provided, which demonstrates a Zeeman splitting\nof the finite bias anomaly."
    },
    {
        "anchor": "Light Induced Aggregation of Specific Single Walled Carbon Nanotubes: We report optically induced aggregation and consequent separation of specific\ndiameter of pristine single walled carbon nanotubes (SWNT) from stable\nsolution. Well dispersed solution of pristine SWNTs, without any surfactant or\nfunctionalization, show rapid aggregation by uniform exposure to UV, visible\nand NIR illumination. Optically induced aggregation linearly increases with\nconsequent increase in the intensity of light. Aggregated SWNTs were separated\nfrom the dispersed supernatant and characterized using absorption and Raman\nspectroscopy. Separated SWNTs distinctly show enrichment of specific SWNTs\nunder UV visible and NIR illumination.",
        "positive": "Aharonov-Bohm oscillations in Dirac semimetal Cd3As2 nanowires: Three-dimensional Dirac semimetals, a three-dimensional analogue of graphene,\nare unusual quantum materials with massless Dirac fermions, which can be\nfurther converted to Weyl fermions by breaking time reversal or inversion\nsymmetry. Topological surface states with Fermi arcs are predicted on the\nsurface and have been observed by angle-resolved photoemission spectroscopy\nexperiments. Although the exotic transport properties of the bulk Dirac cones\nhave been demonstrated, it is still a challenge to reveal the surface states\nvia transport measurements due to the highly conductive bulk states. Here, we\nshow Aharonov-Bohm oscillations in individual single-crystal Cd3As2 nanowires\nwith low carrier concentration and large surface-to-volume ratio, providing\ntransport evidence of the surface state in three-dimensional Dirac semimetals.\nMoreover, the quantum transport can be modulated by tuning the Fermi level\nusing a gate voltage, enabling a deeper understanding of rich physics residing\nin Dirac semimetals."
    },
    {
        "anchor": "Weak topological insulator with protected gapless helical states: A workable model for describing dislocation lines introduced into a\nthree-dimensional topological insulator is proposed. We show how fragile\nsurface Dirac cones of a weak topological insulator evolve into protected\ngapless helical modes confined to the vicinity of dislocation line. It is\ndemonstrated that surface Dirac cones of a topological insulator (either strong\nor weak) acquire a finite-size energy gap, when the surface is deformed into a\ncylinder penetrating the otherwise surface-less system. We show that when a\ndislocation with a non-trivial Burgers vector is introduced, the finite-size\nenergy gap play the role of stabilizing the one-dimensional gapless states.",
        "positive": "Disorder-Induced Resistive Anomaly Near Ferromagnetic Phase Transitions: We show that the resistivity rho(T) of disordered ferromagnets near, and\nabove, the Curie temperature T_c generically exhibits a stronger anomaly than\nthe scaling-based Fisher-Langer prediction. Treating transport beyond the\nBoltzmann description, we find that within mean-field theory, d\\rho/dT exhibits\na |T-T_c|^{-1/2} singularity near T_c. Our results, being solely due to\nimpurities, are relevant to ferromagnets with low T_c, such as SrRuO3 or\ndiluted magnetic semiconductors, whose mobility near T_c is limited by\ndisorder."
    },
    {
        "anchor": "Minimal realization of the Orbital Kondo effect in a Quantum Dot with\n  two Leads: We demonstrate theoretically how the Kondo effect may be observed in the\ntransport of spinless electrons through a quantum dot. The role of conduction\nelectron spin is played by a lead index. The Kondo effect takes place if there\nare two close levels in the dot populated by a single electron. For\ntemperatures exceeding the Kondo temperature $T\\gg T_K$ the conductance is\nmaximal if the levels are exactly degenerate. However, at zero temperature the\nconductance is zero at the SU(2) symmetric point, but reaches the unitary limit\n$G = e^2/h$ for some finite value of the level splitting $\\Delta\\eps\\sim T_K$.\nIntroducing the spin-1/2 for electrons and having two degenerate orbital levels\nin the dot allows to observe the SU(4) Kondo effect in a single dot coupled to\ntwo leads.",
        "positive": "Electronic structures and optical properties of realistic transition\n  metal dichalcogenide heterostructures from first principles: We calculate from first principles the electronic structure and optical\nproperties of a number of transition metal dichalcogenide (TMD) bilayer\nheterostructures consisting of MoS2 layers sandwiched with WS2, MoSe2, MoTe2,\nBN, or graphene sheets. Contrary to previous works, the systems are constructed\nin such a way that the unstrained lattice constants of the constituent\nincommensurate monolayers are retained. We find strong interaction between the\n\\Gamma-point states in all TMD/TMD heterostructures, which can lead to an\nindirect gap. On the other hand, states near the K-point remain as in the\nmonolayers. When TMDs are paired with BN or graphene layers, the interaction\naround \\Gamma-point is negligible, and the electronic structure resembles that\nof two independent monolayers. Calculations of optical properties of the\nMoS2/WS2 system show that even when the valence and conduction band edges are\nlocated in different layers, the mixing of optical transitions is minimal, and\nthe optical characteristics of the monolayers are largely retained in these\nheterostructures. The intensity of interlayer transitions is found to be\nnegligibly small, a discouraging result for engineering the optical gap of TMDs\nby heterostructuring."
    },
    {
        "anchor": "Full counting statistics of information content in the presence of\n  Coulomb interaction: We calculate the R\\'enyi entropy of a positive integer order $M$ for a\nreduced density matrix of a single-level quantum dot connected to left and\nright leads. We exploit a $2 \\times 2$ modified Keldysh Green function matrix\nobtained by the discrete Fourier transform of a $2 M \\times 2M$ multi-contour\nKeldysh Green function matrix. A moment generating function of self-information\nis deduced from the analytic continuation of $M$ to the complex plane. We\ncalculate the probability distribution of self-information and find that,\nwithin the Hartree approximation, the on-site Coulomb interaction affects rare\nevents and modifies a bound of the probability distribution. A simple equality,\nfrom which an upper bound of the average, i.e., the entanglement entropy, would\nbe inferred, is presented. For noninteracting electrons, the entanglement\nentropy is expressed with current cumulants of the full-counting statistics of\nelectron transport.",
        "positive": "Adiabaticity in semiclassical nanoelectromechanical systems: We compare the semiclassical description of NEMS within and beyond the\nadiabatic approximation. We consider a NEMS model which contains a single\nphonon (oscillator) mode linearly coupled to an electronic few-level system in\ncontact with external particle reservoirs (leads). Using Feynman-Vernon\ninfluence functional theory, we derive a Langevin equation for the oscillator\ntrajectory that is non-perturbative in the system-leads coupling. A stationary\nelectronic current through the system generates nontrivial dynamical behavior\nof the oscillator, even in the adiabatic regime. The 'backaction' of the\noscillator onto the current is studied as well. For the two simplest cases of\none and two coupled electronic levels, we discuss the differences between the\nadiabatic and the non-adiabatic regime of the oscillator dynamics."
    },
    {
        "anchor": "Equilibration of quantum Hall edge states by an Ohmic contact: Ohmic contacts are crucial elements of electron optics that have not received\na clear theoretical description yet. We propose a model of an Ohmic contact as\na piece of metal of the finite capacitance $C$ attached to a quantum Hall edge.\nIt is shown that charged quantum Hall edge states may have weak coupling to\nneutral excitations in an Ohmic contact. Consequently, despite being a\nreservoir of neutral excitations, an Ohmic contact is not able to efficiently\nequilibrate edge states if its temperature is smaller than $\\hbar\\Omega_c$,\nwhere $\\Omega_c$ is the inverse RC time of the contact. This energy scale for a\nfloating contact may become as large as the single-electron charging energy\n$e^2/ C$.",
        "positive": "Exact time-dependent density functional theory for impurity models: We employ the density matrix renormalization group to construct the exact\ntime-dependent exchange correlation potential for an impurity model with an\napplied transport voltage. Even for short-ranged interaction we find an\ninfinitely long-ranged exchange correlation potential which is built up\n{instantly} after switching on the voltage. Our result demonstrates the\nfundamental difficulties of transport calculations based on time-dependent\ndensity functional theory. While formally the approach works, important\ninformation can be missing in the ground-state functionals and may be hidden in\nthe usually unknown non-equilibrium functionals."
    },
    {
        "anchor": "Ferromagnetic resonance in periodic particle arrays: We report measurements of the ferromagnetic resonance (FMR) spectra of arrays\nof submicron size periodic particle arrays of permalloy produced by\nelectron-beam lithography. In contrast to plane ferromagnetic films, the\nspectra of the arrays show a number of additional resonance peaks, whose\nposition depends strongly on the orientation of the external magnetic field and\nthe interparticle interaction. Time-dependent micromagnetic simulation of the\nac response show that these peaks are associated with coupled exchange and\ndipolar spin wave modes",
        "positive": "Time-Reversal Invariant Parafermions in Interacting Rashba Nanowires: We propose a scheme to generate pairs of time-reversal invariant\nparafermions. Our setup consists of two quantum wires with opposite Rashba spin\norbit interactions coupled to an $s$-wave superconductor, in the presence of\nelectron-electron interactions. The zero-energy bound states localized at the\nwire ends arise from the interplay between two types of proximity induced\nsuperconductivity: the usual intrawire superconductivity and the interwire\nsuperconductivity due to crossed Andreev reflections. If the latter dominates,\nwhich is the case for strong electron-electron interactions, the system\nsupports Kramers pair of parafermions. Moreover, the scheme can be extended to\na two-dimensional sea of time-reversal invariant parafermions."
    },
    {
        "anchor": "Hybrid magnonics for short-wavelength spin waves facilitated by a\n  magnetic heterostructure: Recent research on hybrid magnonics has been restricted by the long magnon\nwavelengths of the ferromagnetic resonance modes. We present an experiment on\nthe hybridization of 250-nm wavelength magnons with microwave photons in a\nmultimode magnonic system consists of a planar cavity and a magnetic bilayer.\nThe coupling between magnon modes in the two magnetic layers, i.e., the uniform\nmode in Permalloy (Py) and the perpendicular standing spin waves (PSSWs) in\nYIG, serves as an effective means for exciting short-wavelength PSSWs, which is\nfurther hybridized with the photon mode of the microwave resonator. The\ndemonstrated magnon-photon coupling approaches the superstrong coupling regime,\nand can even be achieved near zero bias field.",
        "positive": "A dynamic localization of 2D electrons at mesoscopic length scales: We have investigated the local magneto-transport in high-quality 2D electron\nsystems at low carrier densities. The positive magneto-resistance in\nperpendicular magnetic field in the strongly insulating regime has been\nmeasured to evaluate the spatial concentration of localized states within a\nmesoscopic region of the samples. An independent measurement of the electron\ndensity within the same region shows an unexpected correspondence between the\ndensity of electrons in the metallic regime and that of the localized states in\nthe insulating phase. We have argued that this correspondence manifests a rigid\ndistribution of electrons at low densities."
    },
    {
        "anchor": "Achieving quantized transport in Floquet topological insulators via\n  energy filters: Due to photon-assisted transport processes, chiral edge modes induced by\nperiodic driving do not directly mediate quantized transport. Here we show how\nnarrow bandwidth \"energy filters\" can restore quantization by suppressing\nphoton assisted transport through Floquet sidebands. We derive a Floquet\nLandauer type equation to describe transport through such an energy-filtered\nsetup, and show how the filter can be integrated out to yield a sharply\nenergy-dependent renormalized system-lead coupling. We show analytically and\nthrough numerical simulations that a nearly quantized conductance can be\nachieved in both off-resonantly and resonantly induced quasienergy gaps when\nfilters are introduced. The conductance approaches the appropriate quantized\nvalue on each plateau with increasing system and filter size. We introduce a\n\"Floquet distribution function\" and show both analytically and numerically that\nit approaches the equilibrium Fermi-Dirac form when narrow-band filters are\nintroduced, highlighting the mechanism that restores quantized transport.",
        "positive": "Engineered valley-orbit splittings in quantum confined nanostructures in\n  silicon: An important challenge in silicon quantum electronics in the few electron\nregime is the potentially small energy gap between the ground and excited\norbital states in 3D quantum confined nanostructures due to the multiple valley\ndegeneracies of the conduction band present in silicon. Understanding the\n\"valley-orbit\" (VO) gap is essential for silicon qubits, as a large VO gap\nprevents leakage of the qubit states into a higher dimensional Hilbert space.\nThe VO gap varies considerably depending on quantum confinement, and can be\nengineered by external electric fields. In this work we investigate VO\nsplitting experimentally and theoretically in a range of confinement regimes.\nWe report measurements of the VO splitting in silicon quantum dot and donor\ndevices through excited state transport spectroscopy. These results are\nunderpinned by large-scale atomistic tight-binding calculations involving over\n1 million atoms to compute VO splittings as functions of electric fields, donor\ndepths, and surface disorder. The results provide a comprehensive picture of\nthe range of VO splittings that can be achieved through quantum engineering."
    },
    {
        "anchor": "Chiral current circulation and $\\mathcal{PT}$ symmetry in a trimer of\n  oscillators: We present a simple quantum theory of a bosonic trimer in a triangular\nconfiguration, subject to gain and loss in an open quantum systems approach.\nImportantly, the coupling constants between each oscillator are augmented by\ncomplex arguments, which give rise to various asymmetries. In particular, one\nmay tune the complex phases to induce chiral currents, including the special\ncase of completely unidirectional (or one-way) circulation when certain\nconditions are met regarding the coherent and incoherent couplings. When our\ngeneral theory is recast into a specific non-Hermitian Hamiltonian, we find\ninteresting features in the trimer population dynamics close to the exceptional\npoints between phases of broken and unbroken $\\mathcal{PT}$ symmetry. Our\ntheoretical work provides perspectives for the experimental realization of\nchiral transport at the nanoscale in a variety of accessible nanophotonic and\nnanoplasmonic systems, and paves the way for the potential actualization of\nnonreciprocal devices.",
        "positive": "Investigation of indirect excitons in bulk $2H$-MoS$_2$ using\n  transmission electron energy-loss spectroscopy: We have investigated indirect excitons in bulk $2H$-MoS$_2$ using\ntransmission electron energy-loss spectroscopy. The electron energy-loss\nspectra were measured for various momentum transfer values parallel to the\n$\\Gamma$K and $\\Gamma$M directions of the Brillouin zone. The results allowed\nthe identification of the indirect excitons between the valence band\nK$_{\\mathrm{v}}$ and conduction band $\\Lambda_{\\mathrm{c}}$ points, the\n$\\Gamma_{\\mathrm{v}}$ and K$_{\\mathrm{c}}$ points as well as adjacent\nK$_{\\mathrm{v}}$ and K$^{\\prime}_\\textrm{c}$ points. The energy-momentum\ndispersions for the K$_{\\mathrm{v}}$-$\\Lambda_{\\mathrm{c}}$,\n$\\Gamma_{\\mathrm{v}}$-K$_{\\mathrm{c}}$ and\nK$_{\\mathrm{v1}}$-K$^{\\prime}_\\textrm{c}$ excitons along the $\\Gamma$K line are\npresented. The former two transitions exhibit a quadratic dispersion which\nallowed calculating their effective exciton masses based on the effective mass\napproximation. The K$_\\mathrm{v1}$-K$^{\\prime}_\\textrm{c}$ transition follows a\nmore linear dispersion relationship."
    },
    {
        "anchor": "Critical wave functions in disordered graphene: In order to elucidate the presence of non-localized states in doped graphene,\nan scaling analysis of the wave function moments known as inverse participation\nratios is performed. The model used is a tight- binding hamiltonian considering\nnearest and next-nearest neighbors with random substitutional impurities. Our\nfindings indicate the presence of non-normalizable wave functions that follow a\ncritical (power-law) decay, which are between a metallic and insulating\nbehavior. The power-law exponent distribution is robust against the inclusion\nof next-nearest neighbors and on growing the system size.",
        "positive": "Microscopic Origin of the Valley Hall Effect in Transition Metal\n  Dichalcogenides Revealed by Wavelength Dependent Mapping: The band structure of many semiconducting monolayer transition metal\ndichalcogenides (TMDs) possesses two degenerate valleys, with equal and\nopposite Berry curvature. It has been predicted that, when illuminated with\ncircularly polarized light, interband transitions generate an unbalanced\nnon-equilibrium population of electrons and holes in these valleys, resulting\nin a finite Hall voltage at zero magnetic field when a current flows through\nthe system. This is the so-called valley Hall effect that has recently been\nobserved experimentally. Here, we show that this effect is mediated by\nphoto-generated neutral excitons and charged trions, and not by inter-band\ntransitions generating independent electrons and holes. We further demonstrate\nan experimental strategy, based on wavelength dependent spatial mapping of the\nHall voltage, which allows the exciton and trion contributions to the valley\nHall effect to be discriminated in the measurement. These results represent a\nsignificant step forward in our understanding of the microscopic origin of\nphoto-induced valley Hall effect in semiconducting transition metal\ndichalcogenides, and demonstrate experimentally that composite quasi-particles,\nsuch as trions, can also possess a finite Berry curvature."
    },
    {
        "anchor": "Magneto-optical response of graphene: probing substrate interactions: Magneto-optical transitions between Landau levels can provide precise\nspectroscopic information on the electronic structure and excitation spectra of\ngraphene, enabling probes of substrate and many-body effects. We calculate the\nmagneto-optical conductivity of large-size graphene flakes using a\ntight-binding approach. Our method allows us to directly compare the\nmagneto-optical response of an isolated graphene flake with one aligned on\nhexagonal boron nitride giving rise to a periodic superlattice potential. The\nsubstrate interaction induces band gaps away from the Dirac point. In the\npresence of a perpendicular magnetic field Landau-level like structures emerge\nfrom these zero-field band gaps. The energy dependence of these satellite\nstructures is, however, not easily accessible by conventional probes of the\ndensity of states by varying the back-gate voltage. Here we propose the\nmagneto-optical probing of the superlattice perturbed spectrum. Our simulation\nincludes magneto-excitonic effects in first-order perturbation theory. Our\napproach yields a quantitative explanation of recently observed Landau-level\ndependent renormalizations of the Fermi velocity.",
        "positive": "Lorentz violation in Dirac and Weyl semimetals: We propose a correspondence between the description of emergent Lorentz\nsymmetry in condensed-matter systems and the established general effective\nfield theory for Lorentz violation in fundamental theories of spacetime and\nmatter. This correspondence has potential implications in both directions. We\nillustrate the proposal by investigating its consequences for the spectral and\ntransport properties of Dirac and Weyl semimetals. Particular realizations of\nthis framework give rise to Dirac nodal spectra with nodal lines and rings. We\ndemonstrate a bulk-boundary correspondence between bulk topological invariants\nand drumhead surface states of these Dirac nodal semimetals. We calculate their\ntransport coefficients in leading-order perturbation theory, thereby\ncharacterizing the unconventional electromagnetic response due to small\ndeviations from emergent Lorentz invariance. Some prospective future\napplications of the correspondence are outlined."
    },
    {
        "anchor": "Aging effects in critical behavior of Heisenberg anisotropic ultrathin\n  films: We present the results of Monte-Carlo studies of the non-equilibrium\nproperties of ferromagnetic Heisenberg films. Aging effects were observed in\nnon-equilibrium critical behavior. The calculations were carried out for both\nhigh-temperature and low-temperature initial states. The characteristic\ncorrelation time, which diverges at the transition temperature in the\nthermodynamic limit, was obtained as a function of system size and waiting\ntime.",
        "positive": "Quantifying many-body effects by high-resolution Fourier transform\n  scanning tunneling spectroscopy: Many-body phenomena are ubiquitous in solids, as electrons interact with one\nanother and the many excitations arising from lattice, magnetic, and electronic\ndegrees of freedom. These interactions can subtly influence the electronic\nproperties of materials ranging from metals, exotic materials such as graphene,\nand topological insulators, or they can induce new phases of matter, as in\nconventional and unconventional superconductors, heavy fermion systems, and\nother systems of correlated electrons. As no single theoretical approach\ndescribes all such phenomena, the development of versatile methods for\nmeasuring many-body effects is key for understanding these systems. To date,\nangle-resolved photoemission spectroscopy (ARPES) has been the method of choice\nfor accessing this physics by directly imaging momentum resolved electronic\nstructure. Scanning tunneling microscopy/spectroscopy (STM/S), renown for its\nreal-space atomic resolution capability, can also access the electronic\nstructure in momentum space using Fourier transform scanning tunneling\nspectroscopy (FT-STS). Here, we report a high-resolution FT-STS measurement of\nthe Ag(111) surface state, revealing fine structure in the otherwise parabolic\nelectronic dispersion. This deviation is induced by interactions with lattice\nvibrations and has not been previously resolved by any technique. This study\nadvances STM/STS as a method for quantitatively probing many-body interactions.\nCombined with the spatial sensitivity of STM/STS, this technique opens a new\navenue for studying such interactions at the nano-scale."
    },
    {
        "anchor": "Comment on \"Weyl fermions and the anomalous Hall effect in metallic\n  ferromagnets\": We point out that, contrary to an assertion by Chen, Bergman and Burkov\n[Phys. Rev. B 88, 125110 (2013)], the non-quantized part of the intrinsic\nanomalous Hall conductivity can indeed be expressed as a Fermi-surface property\neven when Weyl points are present in the bandstructure.",
        "positive": "Interplay between Nitrogen Dopants and Native Point Defects in Graphene: To understand the interaction between nitrogen dopants and native point\ndefects in graphene, we have studied the energetic stability of N-doped\ngraphene with vacancies and Stone-Wales (SW) defect by performing the density\nfunctional theory calculations. Our results show that N substitution\nenergetically prefers to occur at the carbon atoms near the defects, especially\nfor those sites with larger bond shortening, indicating that the defect-induced\nstrain plays an important role in the stability of N dopants in defective\ngraphene. In the presence of monovacancy, the most stable position for N dopant\nis the pyridinelike configuration, while for other point defects studied (SW\ndefect and divacancies) N prefers a site in the pentagonal ring. The effect of\nnative point defects on N dopants is quite strong: While the N doping is\nendothermic in defect-free graphene, it becomes exothermic for defective\ngraphene. Our results imply that the native point defect and N dopant attract\neach other, i.e., cooperative effect, which means that substitutional N dopants\nwould increase the probability of point defect generation and vice versa. Our\nfindings are supported by recent experimental studies on the N doping of\ngraphene. Furthermore we point out possibilities of aggregation of multiple N\ndopants near native point defects. Finally we make brief comments on the effect\nof Fe adsorption on the stability of N dopant aggregation."
    },
    {
        "anchor": "Conductance Switching of Azobenzene-Based Self-Assembled Monolayers on\n  Cobalt Probed by UHV Conductive-AFM: We report the formation of self-assembled monolayers of a molecular\nphotoswitch (azobenzene-bithiophene derivative, AzBT) on cobalt via a thiol\ncovalent bond. We study the electrical properties of the molecular junctions\nformed with the tip of a conductive atomic force microscope under ultra-high\nvacuum. The statistical analysis of the current-voltage curves shows two\ndistinct states of the molecule conductance, suggesting the coexistence of both\nthe trans and cis azobenzene isomers on the surface. The cis isomer population\n(trans isomer) increases (decreases) upon UV light irradiation. The situation\nis reversed under blue light irradiation. The experiments are confronted to\nfirst-principle calculations performed on the molecular junctions with the\nNon-Equilibrium Green's Function formalism combined with Density Functional\nTheory (NEGF/DFT). The theoretical results consider two different molecular\norientations for each isomer. Whereas the orientation does not affect the\nconductance of the trans isomer, it significantly modulates the conductance of\nthe cis isomer and the resulting conductance ON/OFF ratio of the molecular\njunction. This helps identifying the molecular orientation at the origin of the\nobserved current differences between the trans and cis forms. The ON state is\nassociated to the trans isomer irrespective of its orientation in the junction,\nwhile the OFF state is identified as a cis isomer with its azobenzene moiety\nfolded upward with respect to the bithiophene core. The experimental and\ncalculated ON/OFF conductance ratios have a similar order of magnitude. This\nconductance ratio seems reasonable to make these Co-AzBT molecular junctions a\ngood test-bed to further explore the relationship between the spin-polarized\ncharge transport, the molecule conformation and the molecule-Co spinterface.",
        "positive": "Inductive determination of the optimum tunnel barrier thickness in\n  magnetic tunnelling junction stacks for spin torque memory applications: We use pulsed inductive microwave magnetometry to study the precessional\nmagnetization dynamics of the free layer in CoFeB/MgO/CoFeB based magnetic\ntunnelling junction stacks with varying MgO barrier thickness. From the field\ndependence of the precession frequency we are able to derive the uniaxial\nanisotropy energy and the exchange coupling between the free and the pinned\nlayer. Furthermore the field dependence of the effective damping parameter is\nderived. Below a certain threshold barrier thickness we observe an increased\neffective damping for antiparallel orientation of free and pinned layer which\nwould inhibit reversible low current density spin torque magnetization\nreversal. Such inductive measurements, in combination with wafer probe station\nbased magneto transport experiments, allow a fast determination of the optimum\ntunnel barrier thickness range for spin torque memory applications in a\nlithography free process."
    },
    {
        "anchor": "Non-perturbation theory of electronic dynamic conductivity for\n  two-barrier resonance tunnel nano-structure: The non-perturbation theory of electronic dynamic conductivity for open\ntwo-barrier resonance tunnel structure is established for the first time within\nthe model of rectangular potentials and different effective masses of electrons\nin the elements of nano-structure and the wave function linear over the\nintensity of electromagnetic field. It is proven that the results of the theory\nof dynamic conductivity, developed earlier in weak signal approximation within\nthe perturbation method, qualitatively and quantitatively correlate with the\nobtained results. The advantage of non-perturbation theory is that it can be\nextended to the case of electronic currents interacting with strong\nelectromagnetic fields in open multi-shell resonance tunnel nano-structures, as\nactive elements of quantum cascade lasers and detectors.",
        "positive": "Floquet topological transitions in extended Kane-Mele models with\n  disorder: In this work we use Floquet theory to theoretically study the influence of\ncircularly polarized light on disordered two-dimensional models exhibiting\ntopological transitions. We find circularly polarized light can induce a\ntopological transition in extended Kane-Mele models that include additional\nhopping terms and on-site disorder. The topological transitions are understood\nfrom the Floquet-Bloch band structure of the clean system at high symmetry\npoints in the first Brillouin zone. The light modifies the equilibrium band\nstructure of the clean system in such a way that the smallest gap in the\nBrillouin zone can be shifted from the $M$ points to the $K(K')$ points, the\n$\\Gamma$ point, or even other lower symmetry points. The movement of the\nminimal gap point through the Brillouin zone as a function of laser parameters\nis explained in the high frequency regime through the Magnus expansion. In the\ndisordered model, we compute the Bott index to reveal topological phases and\ntransitions. The disorder can induce transitions from topologically non-trivial\nstates to trivial states or vice versa, both examples of Floquet topological\nAnderson transitions. As a result of the movement of the minimal gap point\nthrough the Brillouin zone as a function of laser parameters, the nature of the\ntopological phases and transitions is laser-parameter dependent--a contrasting\nbehavior to the Kane-Mele model."
    },
    {
        "anchor": "Unconventional Planar Hall Effect in Exchange-Coupled Topological\n  Insulator-Ferromagnetic Insulator Heterostructures: The Dirac electrons occupying the surface states (SSs) of topological\ninsulators (TIs) have been predicted to exhibit many exciting magneto-transport\nphenomena. Here we report on the first experimental observation of an\nunconventional planar Hall effect (PHE) and an electrically gate-tunable\nhysteretic planar magnetoresistance (PMR) in EuS/TI heterostructures, in which\nEuS is a ferromagnetic insulator (FMI) with an in-plane magnetization. In such\nexchange-coupled FMI/TI heterostructures, we find a significant (suppressed)\nPHE when the in-plane magnetic field is parallel (perpendicular) to the\nelectric current. This behavior differs from previous observations of the PHE\nin ferromagnets and semiconductors. Furthermore, as the thickness of the 3D TI\nfilms is reduced into the 2D limit, in which the Dirac SSs develop a\nhybridization gap, we find a suppression of the PHE around the charge neutral\npoint indicating the vital role of Dirac SSs in this phenomenon. To explain our\nfindings, we outline a symmetry argument that excludes linear-Hall mechanisms\nand suggest two possible non-linear Hall mechanisms that can account for all\nthe essential qualitative features in our observations.",
        "positive": "Spin-orbit dynamics of single acceptor atoms in silicon: Two-level quantum systems with strong spin-orbit coupling allow for\nall-electrical qubit control and long-distance qubit coupling via microwave and\nphonon cavities, making them of particular interest for scalable quantum\ninformation technologies. In silicon, a strong spin-orbit coupling exists\nwithin the spin-3/2 system of acceptor atoms and their energy levels and\nproperties are expected to be highly tunable. Here we show the influence of\nlocal symmetry tuning on the acceptor spin-dynamics, measured in the\nsingle-atom regime. Spin-selective tunneling between two coupled boron atoms in\na commercial CMOS transistor is utilised for spin-readout, which allows for the\nprobing of the two-hole spin relaxation mechanisms. A relaxation-hotspot is\nmeasured and explained by the mixing of acceptor heavy and light hole states.\nFurthermore, excited state spectroscopy indicates a magnetic field controlled\nrotation of the quantization axes of the atoms. These observations demonstrate\nthe tunability of the spin-orbit states and dynamics of this spin-3/2 system."
    },
    {
        "anchor": "Dephasing of conduction electrons by magnetic impurities in Cu/Ni and\n  Cu/Cr samples: Influence of spin-glass transition on the superconducting\n  proximity effect: The dependence of the superconducting proximity effect on the amount of\nmagnetic impurities in the normal part of Andreev interferometers has been\nstudied experimentally. The dephasing rates obtained from fitting experimental\ndata to quasiclassical theory of the proximity effect are consistent with the\nspin flip scattering from Cr impurities forming a local moment in the Cu host.\nIn contrast, Ni impurities do not form a local moment in Cu and as a result\nthere is no extra dephasing from Ni as long as Cu/Ni alloy remain paramagnetic.",
        "positive": "Oscillatory Thickness Dependence of the Coercive Field in Magnetic 3D\n  Anti-Dot Arrays: We present studies on magnetic nano-structures with 3D architectures,\nfabricated using electrodeposition in the pores of well-ordered templates\nprepared by self-assembly of polystyrene latex spheres. The coercive field is\nfound to demonstrate an oscillatory dependence on film thickness reflecting the\npatterning transverse to the film plane. Our results demonstrate that 3D\npatterned magnetic materials are prototypes of a new class of geometrical\nmultilayer structures in which the layering is due to local shape effects\nrather then compositional differences."
    },
    {
        "anchor": "Spontaneous and Superfluid Chiral Edge States in Exciton-Polariton\n  Condensates: We present a scheme of interaction-induced topological bandstructures based\non the spin anisotropy of exciton-polaritons in semiconductor microcavities. We\npredict theoretically that this scheme allows the engineering of topological\ngaps, without requiring a magnetic field or strong spin-orbit interaction\n(transverse electric-transverse magnetic splitting). Under non-resonant\npumping, we find that an initially topologically trivial system undergoes a\ntopological transition upon the spontaneous breaking of phase symmetry\nassociated with polariton condensation. Under resonant coherent pumping, we\nfind that it is also possible to engineer a topological dispersion that is\nlinear in wavevector -- a property associated with polariton superfluidity.",
        "positive": "Tunneling Effects on Fine-Structure Splitting in Quantum Dot Molecules: We theoretically study the effects of bias-controlled interdot tunneling in\nvertically coupled quantum dots on the emission properties of spin excitons in\nvarious bias-controlled tunneling regimes. As a main result, for strongly\ncoupled dots we predict substantial reduction of optical fine structure\nsplitting without any drop in the optical oscillator strength. This special\nreduction diminishes the distinguibility of polarized decay paths in cascade\nemission processes suggesting the use of stacked quantum dot molecules as\nentangled photon-pair sources."
    },
    {
        "anchor": "Counter operation in nonlinear micro-electro-mechanical resonators: This paper discusses a logical operation of multi-memories that consist of\ncoupled nonlinear micro-electro-mechanical systems (MEMS) resonators. A MEMS\nresonator shows two coexisting stable states when nonlinear responses appear.\nPrevious studies addressed that a micro- or nano-electrical-mechanical\nresonator can be utilized as a mechanical 1-bit memory or mechanical logic\ngates. The next phase is the development of logic system with coupled\nmulti-resonators. From the viewpoint of application of nonlinear dynamics in\ncoupled MEMS resonators, we show the first experimental success of the\ncontrolling nonlinear behavior as a 2-bit binary counter.",
        "positive": "Charge dynamics in two-electron quantum dots: We investigate charge dynamics in a two-electron double quantum dot. The\nquantum dot is manipulated by using a time-dependent external voltage that\ninduces charge oscillations between the dots. We study the dependence of the\ncharge dynamics on the external magnetic field and on the periodicity of the\nexternal potential. We find that for suitable parameter values, it is possible\nto induce both one-electron and two-electron oscillations between the dots."
    },
    {
        "anchor": "Charge Fractionalization in a Kondo Device: We study nonequilibrium transport through a charge Kondo device realizing the\ntwo-channel Kondo critical point in a recent experiment by Iftikhar et al. By\ncomputing the current and shot noise at low voltages near the critical point,\nwe obtain a universal Fano factor $e^*/e=1/2$. We identify elementary transport\nprocesses as weak scattering of emergent fermions carrying half-integer charge\nquantum numbers. This forms an experimental fingerprint for fractionalization\nin a non-Fermi liquid, which, compared to spin-Kondo devices, could be observed\nat elevated temperatures.",
        "positive": "The Role of the Exchange-Correlation Potential in ab initio Electron\n  Transport Calculations: The effect of the exchange-correlation potential in ab initio electron\ntransport calculations is investigated by constructing optimized effective\npotentials (OEP) using different energy functionals or the electron density\nfrom second-order perturbation theory. We calculate electron transmission\nthrough two atomic chain systems, one with charge transfer and one without.\nDramatic effects are caused by two factors: changes in the energy gap and the\nself-interaction error. The error in conductance caused by the former is about\none order of magnitude while that caused by the latter ranges from several\ntimes to two orders of magnitude, depending on the coupling strength and charge\ntransfer. The implications for accurate quantum transport calculations are\ndiscussed."
    },
    {
        "anchor": "Carbon nanotube as a nanoscale Cherenkov--type light emitter - nanoFEL: A mechanism of stimulated emission of electromagnetic radiation by an\nelectron beam in carbon nanotubes is theoretically considered. Three basic\nproperties of carbon nanotubes, a strong slowing down of surface\nelectromagnetic waves, ballisticity of the electron motion over typical\nnanotube length, and extremely high electron current density reachable in\nnanotubes, allow proposing them as candidates for the development of nano-scale\nChernekov-type emitters, analogous to traveling wave tube and free electron\nlaser. Dispersion equations of the electron beam instability and the threshold\nconditions of the stimulated emission have been derived and analyzed,\ndemonstrating realizability of the nanotube-based nanoFEL at realistic\nparameters of nanotubes and electronic beams.",
        "positive": "Numerical study of quantum Hall effect in two-dimensional multi-band\n  system: single- and multi-layer graphene: The Chern numbers which correspond to quantized Hall conductance\n$\\sigma_{xy}$ were calculated for single- and bi-layer honeycomb lattices. The\nquantization of $\\sigma_{xy}$ occurs in entire energy range. Several large\njumps of Chern numbers appear at van-Hove singularities of energy bands without\nmagnetic fields. The plateauxof $\\sigma_{xy}$ are discussed from semi-classical\nquantization."
    },
    {
        "anchor": "Fabrication of Metal Nanoscale Devices on Insulating Membranes by\n  High-Resolution Atom Ablation: Transmission electron beams (TEBs) have long been used to study and\nmanipulate materials at nanometer scales. In the late 1970's, Cherns\ndemonstrated surface pitting in Au films upon exposure to a 1MeV TEB and\nobserved crystal dislocations in quartz. Soon after, electron beam irradiation\nwas used to drill nanoholes and lines in NaCl crystals, alumina sheets, CaF2\nand MgO. More recent examples include the drilling of nanoholes in silicon,\nstainless steel, and in Si3N4 and SiO2 membranes. In this Letter we demonstrate\na new and highly flexible application of TEB-based fabrication to produce\nintricate metal geometries and fully integrated devices, with sub-10 nm\nfeatures, on silicon nitride membranes. Arbitrary metal patterns may be \"carved\nout\" with sub-nanometer accuracy by ablating evaporated (Al, Ni, Cr, Ag, Au)\nmetal films with the ~ 0.5 nm diameter beam of a high resolution transmission\nelectron microscope. In situ imaging of the ablation action allows for\nreal-time feedback control. Specific examples presented here include nanorings,\nnanowires with tailored curvatures and multi-terminal devices with nanoislands\nor nanoholes between the terminals. Importantly, these nanostructures are\nfabricated at precise locations on a chip and seamlessly integrated into\nlarge-scale circuitry. The combination of high resolution, geometrical control\nand yield make this fabrication method rather unique and highly attractive for\nmany applications including nanoelectronics and molecular translocation.",
        "positive": "Meissner transmon qubit - architecture and characterization: We present a new type of transmon split-junction qubit which can be tuned by\nMeissner screening currents in the adjacent superconducting film electrodes.\nThe best detected relaxation time ($T_1$) was of the order of 50 $\\mu$s and the\ndephasing time ($T_2$) about 40 $\\mu$s. The achieved period of oscillation with\nmagnetic field was much smaller than in usual SQUID-based transmon qubits, thus\na strong effective field amplification has been realized. This Meissner qubit\nallows an efficient coupling to superconducting vortices. We present a\nquantitative analysis of the radiation-free energy relaxation in qubits coupled\nto Abrikosov vortices. The observation of coherent quantum oscillations\nprovides strong evidence that vortices can exist in coherent quantum\nsuperpositions of different position states. According to our suggested model,\nthe wave function collapse is defined by Caldeira-Leggett dissipation\nassociated with viscous motion of the vortex cores."
    },
    {
        "anchor": "Room temperature single photon emission from oxidized tungsten\n  disulphide multilayers: Two dimensional systems offer a unique platform to study light matter\ninteraction at the nanoscale. In this work we report on robust quantum emitters\nfabricated by thermal oxidation of tungsten disulphide multilayers. The\nemitters show robust, optically stable, linearly polarized luminescence at room\ntemperature, can be modeled using a three level system, and exhibit moderate\nbunching. Overall, our results provide important insights into understanding of\ndefect formation and quantum emitter activation in 2D materials.",
        "positive": "Anomalous conductivity, Hall factor, magnetoresistance, and thermopower\n  of accumulation layer in $\\text{SrTiO}_3$: We study the low temperature conductivity of the electron accumulation layer\ninduced by the very strong electric field at the surface of $\\text{SrTiO}_3$\nsample. Due to the strongly nonlinear lattice dielectric response, the\nthree-dimensional density of electrons $n(x)$ in such a layer decays with the\ndistance from the surface $x$ very slowly as $n(x) \\propto 1/x^{12/7}$. We show\nthat when the mobility is limited by the surface scattering the contribution of\nsuch a tail to the conductivity diverges at large $x$ because of growing time\nelectrons need to reach the surface. We explore truncation of this divergence\nby the finite sample width, by the bulk scattering rate, or by the crossover to\nthe bulk linear dielectric response with the dielectric constant $\\kappa$. As a\nresult we arrive at the anomalously large mobility, which depends not only on\nthe rate of the surface scattering, but also on the physics of truncation.\nSimilar anomalous behavior is found for the Hall factor, the magnetoresistance,\nand the thermopower."
    },
    {
        "anchor": "Aspects of electron transport through a quantum dot: The work of the Lublin group on the non-equillibrium transport through the\nquantum dot coupled to external leads (normal or superconducting) and subject\nto external time dependent fields has been reviewed.",
        "positive": "Hybrid magnon-phonon cavity for large-amplitude terahertz spin-wave\n  excitation: Terahertz (THz) spin waves or their quanta, magnons, can be efficiently\nexcited by acoustic phonons because these excitations have similar wavevectors\nin the THz regime. THz acoustic phonons can be produced using photoacoustic\nphenomena but typically have a low population and thus a relatively low\ndisplacement amplitude. The magnetization amplitude and population of the\nacoustically excited THz magnons are thus usually small. Using analytical\ncalculations and dynamical phase-field simulations, we show that a freestanding\nmetal/magnetic-insulator (MI)/dielectric multilayer can be designed to produce\nlarge-amplitude THz spin wave via cavity-enhanced magnon-phonon interaction.\nThe amplitude of the acoustically excited THz spin wave in the freestanding\nmultilayer is predicted to be more than ten times larger than in a\nsubstrate-supported multilayer. Acoustically excited nonlinear magnon-magnon\ninteraction is demonstrated in the freestanding multilayer. The simulations\nalso indicate that the magnon modes can be detected by probing the charge\ncurrent in the metal layer generated via spin-charge conversion across the\nMI/metal interface and the resulting THz radiation. Applications of the\nfreestanding multilayer in THz optoelectronic transduction are computationally\ndemonstrated."
    },
    {
        "anchor": "Theory of optically detected spin noise in nanosystems: Theory of spin noise in low dimensional systems and bulk semiconductors is\nreviewed. Spin noise is usually detected by optical means, continuously\nmeasuring the rotation angle of the polarization plane of the probe beam\npassing through the sample. Spin noise spectra yield rich information about the\nspin properties of the system including, for example, $g$-factors of the charge\ncarriers, spin relaxation times, parameters of the hyperfine interaction,\nspin-orbit interaction constants, frequencies and widths of the optical\nresonances. The review describes basic models of spin noise, methods of its\ntheoretical description, and their relation with the experimental results. We\nalso discuss the relation between the spin noise spectroscopy, the strong and\nweak quantum measurements and the spin flip Raman scattering, and analyze\nsimilar effects including manifestations of the charge, current and valley\npolarization fluctuations in the optical response. Possible directions for\nfurther development of the spin noise spectroscopy are outlined.",
        "positive": "Ultrafast collinear scattering and carrier multiplication in graphene: Graphene is emerging as a viable alternative to conventional optoelectronic,\nplasmonic, and nanophotonic materials. The interaction of light with carriers\ncreates an out-of-equilibrium distribution, which relaxes on an ultrafast\ntimescale to a hot Fermi-Dirac distribution, that subsequently cools via phonon\nemission. Here we combine pump-probe spectroscopy, featuring extreme temporal\nresolution and broad spectral coverage, with a microscopic theory based on the\nquantum Boltzmann equation, to investigate electron-electron collisions in\ngraphene during the very early stages of relaxation. We identify the\nfundamental physical mechanisms controlling the ultrafast dynamics in graphene,\nin particular the significant role of ultrafast collinear scattering, enabling\nAuger processes, including charge multiplication, key to improving photovoltage\ngeneration and photodetectors."
    },
    {
        "anchor": "Giant, anomalous piezo-impedance of silicon-on-insulator: A giant, anomalous piezo-response of fully-depleted silicon-on-insulator\n(FD-SOI) devices under mechanical stress is demonstrated using impedance\nspectroscopy. This piezo-response strongly depends on the measurement\nfrequency, $\\omega$, and consists of both a piezoresistance (PZR) and\npiezocapacitance whose maximum values are $\\pi_R = -1100 \\times 10^{-11}$\nPa$^{-1}$ and $\\pi_C = -900 \\times 10^{-11}$ Pa$^{-1}$ respectively. These\nvalues should be compared with the usual bulk PZR in p-type silicon, $\\pi_R= 70\n\\times 10^{-11}$ Pa$^{-1}$. The observations are well described using models of\nspace charge limited electron and hole currents in the presence of fast\nelectronic traps having stress-dependent capture ($\\omega_c$) and emission\nrates. Under steady-state conditions (i.e. when $\\omega \\ll \\omega_c$) where\nthe impedance spectroscopy measurements yield results that are directly\ncomparable with previously published reports of PZR in depleted, silicon\nnano-objects, the overall piezo-response is just the usual, bulk silicon PZR.\nAnomalous PZR is observed only under non-steady-state conditions when $\\omega\n\\approx \\omega_c$, with a symmetry suggesting that the electro-mechanically\nactive fast traps are native Pb$_0$ interface defects. The observations suggest\nnew functionalities for FD-SOI, and shed light on the debate over the PZR of\ncarrier depleted nano-silicon.",
        "positive": "Coherent Single Photon Emission from Colloidal Lead Halide Perovskite\n  Quantum Dots: Chemically prepared colloidal semiconductor quantum dots have long been\nproposed as scalable and color-tunable single emitters in quantum optics, but\nthey have typically suffered from prohibitively incoherent emission. We now\ndemonstrate that individual colloidal lead halide perovskite quantum dots\n(PQDs) display highly efficient single photon emission with optical coherence\ntimes as long as 80 ps, an appreciable fraction of their 210 ps radiative\nlifetimes. These measurements suggest that PQDs should be explored as building\nblocks in sources of indistinguishable single photons and entangled photon\npairs. Our results present a starting point for the rational design of lead\nhalide perovskite-based quantum emitters with fast emission, wide\nspectral-tunability, scalable production, and which benefit from the\nhybrid-integration with nano-photonic components that has been demonstrated for\ncolloidal materials."
    },
    {
        "anchor": "One-dimensional Hubbard-Luttinger model for carbon nanotubes: A Hubbard-Luttinger model is developed for qualitative description of\none-dimensional motion of interacting Pi-conductivity-electrons in carbon\nsingle-wall nanotubes at low temperatures. The low-lying excitations in\none-dimensional electron gas are described in terms of interacting bosons. The\nBogolyubov transformation allows one to describe the system as an ensemble of\nnon-interacting quasi-bosons. Operators of Fermi-excitations and Green\nfunctions of fermions are introduced. The electric current is derived as a\nfunction of potential difference on the contact between a nanotube and a normal\nmetal. Deviations from Ohm law produced by electron-electron short-range\nrepulsion as well as by the transverse quantization in single-wall nanotubes\nare discussed. The results are compared with experimental data.",
        "positive": "Shape-dependence of near-field heat transfer between a spheroidal\n  nanoparticle and a flat surface: We study the radiative heat transfer between a spheroidal metallic\nnanoparticle and a planar metallic sample for near- and far-field distances. In\nparticular, we investigate the shape dependence of the heat transfer in the\nnear-field regime. In comparison with spherical particles, the heat transfer\ntypically varies by factors between 1/2 and 2 when the particle is deformed\nsuch that its volume is kept constant. These estimates help to quantify the\ndeviation of the actual heat transfer recorded by a near-field scanning thermal\nmicroscope from the value provided by a dipole model which assumes a perfectly\nspherical sensor."
    },
    {
        "anchor": "A first-principles study of bilayer 1T'-WTe2/CrI3: A candidate\n  topological spin filter: The ability to manipulate electronic spin channels in 2D materials is crucial\nfor realizing next-generation spintronics. Spin filters are spintronic\ncomponents that polarize spins using external fields or material properties\nlike magnetism. Recently, topological protection from backscattering has\nemerged as an enticing feature through which to enhance the robustness of 2D\nspin filters. In this work, we propose and then characterize one of the first\n2D topological spin filters: bilayer CrI3/1T'-WTe2 (BLCW). To do so, we use a\ncombination of DFT, maximally localized Wannier functions, and quantum\ntransport simulations to demonstrate that the BLCW satisfies the principal\ncriteria for being a topological spin filter; namely that it is gapless,\nexhibits spin-polarized charge transfer (SPCT) from WTe2 to CrI3 that renders\nthe BLCW metallic, and has a topological boundary which retains the edge\nconductance of monolayer (ML) 1T'-WTe2. We observe that the atomic magnetic\nmoments on Cr from DFT are approximately 3.2 mB/Cr in the BL compared to 2.9\nmB/Cr with small negative ferromagnetic (FM) moments induced on the W atoms in\nfreestanding ML CrI3. Subtracting the charge/spin densities of the constituent\nML's from those of the BLCW further reveals SOC-enhanced SPCT from WTe2 to\nCrI3. We find that the BLCW is topologically trivial by showing that its Chern\nnumber is zero. Lastly, we show that interfacial scattering at the boundary\nbetween the terraced materials does not remove WTe2's edge conductance. This\nevidence indicates that BLCW is gapless, magnetic, and topologically trivial,\nmeaning that a terraced WTe2/CrI3 BL heterostructure in which only a portion of\na WTe2 ML is topped with CrI3 is a promising candidate for a 2D topological\nspin filter. Our results further suggest that 1D chiral edge states may be\nrealized by stacking FM ML's, like CrI3, atop 2D nonmagnetic Weyl semimetals\nlike 1T'-WTe2.",
        "positive": "Ca-intercalated graphite as a hydrogen storage material: stability\n  against decomposition into calcium hydride and graphite: We have used calculations based on density functional theory to investigate\nthe energetics of hydrogen absorption in calcium-intercalated graphites. We\nfocus particularly on the absorption energy and the stability of the\nhydrogenated material with respect to decomposition into graphite and calcium\nhydride, which is essential if this material is to be useful for practical H2\nstorage. The calculations are performed with two commonly used approximations\nfor the exchange-correlation energies. Our calculations confirm earlier\npredictions that the absorption energy is approximately -0.2 to -0.4 eV, which\nis favourable for practical use of Ca-intercalated graphite as a hydrogen\nstorage medium. However, we find that the hydrogenated material is strongly\nunstable against decomposition. Our results therefore explain recent\nexperiments which show that H2 does not remain stable in CaC6 but instead forms\na hydride plus graphite."
    },
    {
        "anchor": "Charge-dipole and dipole-dipole interactions in two-dimensional\n  materials: We derive the explicit analytical form for the charge-dipole and\ndipole-dipole interactions in 2D configuration space. We demonstrate that the\nreduction of dimensionality can alter the charge-dipole and dipole-dipole\ninteractions in 2D case. The asymptotics of these interactions at large\ndistances coincide to the charge-dipole and dipole-dipole interactions in 3D\nconfiguration space.",
        "positive": "Topological Sound: Recently, we witnessed a tremendous effort to conquer the realm of acoustics\nas a possible playground to test with sound waves topologically protected wave\npropagation. Acoustics differ substantially from photonic and electronic\nsystems since longitudinal sound waves lack intrinsic spin polarization and\nbreaking the time-reversal symmetry requires additional complexities that both\nare essential in mimicking the quantum effects leading to topologically robust\nsound propagation. In this article, we review the latest efforts to explore\nwith sound waves topological states of quantum matter in two- and\nthree-dimensional systems where we discuss how spin and valley degrees of\nfreedom appear as highly novel ingredients to tailor the flow of sound in the\nform of one-way edge modes and defect-immune protected acoustic waves. Both\nfrom a theoretical stand point and based on contemporary experimental\nverifications, we summarize the latest advancements of the flourishing research\nfrontier on topological sound."
    },
    {
        "anchor": "Isolated resonances in conductance fluctuations in ballistic billiards: We study the isolated resonances occurring in conductance fluctuations of\nballistic electron systems with a classically mixed phase space. In particular,\nwe calculate the conductance and Wigner-Smith time as well as scattering states\nand eigenstates of the open and closed cosine billiard, respectively. We\ndemonstrate that the observed isolated resonances and their scattering states\ncan be associated with eigenstates of the closed system. They can all be\ncategorized as hierarchical or regular, depending on where in a phase space\nrepresentation the corresponding eigenstates are concentrated.",
        "positive": "Probing the wavefunction of the surface states in Bi$_2$Se$_3$\n  topological insulator: a realistic tight-binding approach: We report on microscopic tight-binding modeling of surface states in\nBi$_2$Se$_3$ three-dimensional topological insulator, based on a sp$^3$\nSlater-Koster Hamiltonian, with parameters calculated from density functional\ntheory. The effect of spin-orbit interaction on the electronic structure of the\nbulk and of a slab with finite thickness is investigated. In particular, a\nphenomenological criterion of band inversion is formulated for both bulk and\nslab, based on the calculated atomic- and orbital-projections of the\nwavefunctions, associated with valence and conduction band extrema at the\ncenter of the Brillouin zone. We carry out a thorough analysis of the\ncalculated bandstructures of slabs with varying thickness, where surface states\nare identified using a quantitative criterion according to their spatial\ndistribution. The thickness-dependent energy gap, attributed to inter-surface\ninteraction, and the emergence of gapless surface states for slabs above a\ncritical thickness are investigated. We map out the transition to the\ninfinite-thickness limit by calculating explicitly the modifications in the\nspatial distribution and spin-character of the surface states wavefunction with\nincreasing the slab thickness. Our numerical analysis shows that the system\nmust be approximately forty quintuple-layers thick to exhibit completely\ndecoupled surface states, localized on the opposite surfaces. These results\nhave implications on the effect of external perturbations on the surface states\nnear the Dirac point."
    },
    {
        "anchor": "Robustness of Charge-Qubit Cluster States to Double Quantum Point\n  Contact Measurement: We theoretically investigate the robustness of cluster states in charge qubit\nsystem based on quantum dot (QD) and double quantum point contact (DQPC). Trap\nstate is modeled by an island structure in DQPC and represents a dynamical\nfluctuation. We found that the dynamical fluctuations affect the cluster states\nmore than static fluctuation caused by QD size fluctuation.",
        "positive": "Nonlinear screening of charge impurities in graphene: It is shown that a ``vacuum polarization'' induced by Coulomb potential in\ngraphene leads to a strong suppression of electric charges even for undoped\ncase (no charge carriers). A standard linear response theory is therefore not\napplicable to describe the screening of charge impurities in graphene. In\nparticular, it overestimates essentially the contributions of charge impurities\ninto the resistivity of graphene."
    },
    {
        "anchor": "Optimized Graphene Electrodes for contacting Graphene Nanoribbons: Atomically precise graphene nanoribbons are a promising emerging class of\ndesigner quantum materials with electronic properties that are tunable by\nchemical design. However, many challenges remain in the device integration of\nthese materials, especially regarding contacting strategies. We report on the\ndevice integration of uniaxially aligned and non-aligned 9-atom wide armchair\ngraphene nanoribbons (9-AGNRs) in a field-effect transistor geometry using\nelectron beam lithography-defined graphene electrodes. This approach yields\ncontrolled electrode geometries and enables higher fabrication throughput\ncompared to previous approaches using an electrical breakdown technique.\nThermal annealing is found to be a crucial step for successful device operation\nresulting in electronic transport characteristics showing a strong gate\ndependence. Raman spectroscopy confirms the integrity of the graphene\nelectrodes after patterning and of the GNRs after device integration. Our\nresults demonstrate the importance of the GNR-graphene electrode interface and\npave the way for GNR device integration with structurally well-defined\nelectrodes.",
        "positive": "Superconducting pi qubit with a ferromagnetic Josephson junction: Solid-state qubits have the potential for the large-scale integration and for\nthe flexibility of layout for quantum computing. However, their short\ndecoherence time due to the coupling to the environment remains an important\nproblem to be overcome. We propose a new superconducting qubit which\nincorporates a spin-electronic device: the qubit consists of a superconducting\nring with a ferromagnetic pi junction which has a metallic contact and a normal\nJosephson junction with an insulating barrier. Thus, a quantum coherent\ntwo-level state is formed without an external magnetic field. This feature and\nthe simple structure of the qubit make it possible to reduce its size leading\nto a long decoherence time."
    },
    {
        "anchor": "Kondo effect in electrostatically defined ZnO quantum dots: Quantum devices such as spin qubits have been extensively investigated in\nelectrostatically confined quantum dots using high-quality semiconductor\nheterostructures like GaAs and Si. Here, we present the first demonstration of\nelectrostatically forming the quantum dots in ZnO heterostructures. Through the\ntransport measurement, we uncover the distinctive signature of the Kondo effect\nindependent of the even-odd electron number parity, which contrasts with the\ntypical behavior of the Kondo effect in GaAs. By analyzing temperature and\nmagnetic field dependences, we find that the absence of the even-odd parity in\nthe Kondo effect is not straightforwardly interpreted by the considerations\ndeveloped for conventional semiconductors. We propose that, based on the unique\nparameters of ZnO, electron correlation likely plays a fundamental role in this\nobservation. Our study not only clarifies the physics of correlated electrons\nin the quantum dot but also holds promise for applications in quantum devices,\nleveraging the unique features of ZnO.",
        "positive": "Complete Coherent Control of Silicon-Vacancies in Diamond Nanopillars\n  Containing Single Defect Centers: Arrays of identical and individually addressable qubits lay the foundation\nfor the creation of scalable quantum hardware such as quantum processors and\nrepeaters. Silicon vacancy centers in diamond (SiV) offer excellent physical\nproperties such as low inhomogeneous broadening, fast photon emission, and a\nlarge Debye-Waller factor, while the possibility for all-optical ultrafast\nmanipulation and techniques to extend the spin coherence times make them very\npromising candidates for qubits. Here, we have developed arrays of nanopillars\ncontaining single SiV centers with high yield, and we demonstrate ultrafast\nall-optical complete coherent control of the state of a single SiV center. The\nhigh quality of the chemical vapor deposition (CVD) grown SiV centers provides\nexcellent spectral stability, which allows us to coherently manipulate and\nquasi-resonantly read out the state of individual SiV centers on picosecond\ntimescales using ultrafast optical pulses. This work opens new opportunities\ntowards the creation of a scalable on-chip diamond platform for quantum\ninformation processing and scalable nanophotonics applications."
    },
    {
        "anchor": "Photocurrent generation with two-dimensional van der Waals\n  semiconductors: Two-dimensional (2D) materials have attracted a great deal of interest in\nrecent years. This family of materials allows for the realization of versatile\nelectronic devices and holds promise for next-generation (opto)electronics.\nTheir electronic properties strongly depend on the number of layers, making\nthem interesting from a fundamental standpoint. For electronic applications,\nsemiconducting 2D materials benefit from sizable mobilities and large on/off\nratios, due to the large modulation achievable via the gate field-effect.\nMoreover, being mechanically strong and flexible, these materials can withstand\nlarge strain (>10\\%) before rupture, making them interesting for strain\nengineering and flexible devices. Even in their single layer form,\nsemiconducting 2D materials have demonstrated efficient light absorption,\nenabling large responsivity in photodetectors. Therefore, semiconducting\nlayered 2D materials are strong candidates for optoelectronic applications,\nespecially for photodetection. Here, we review the state-of-the-art in\nphotodetectors based on semiconducting 2D materials, focusing on the transition\nmetal dichalcogenides, novel van der Waals materials, black phosphorus, and\nheterostructures.",
        "positive": "Symmetries and the conductance of graphene nanoribbons with long-range\n  disorder: We study the conductance of graphene nanoribbons with long-range disorder.\nDue to the absence of intervalley scattering from the disorder potential,\ntime-reversal symmetry (TRS) can be effectively broken even without a magnetic\nfield, depending on the type of ribbon edge. Even though armchair edges\ngenerally mix valleys, we show that metallic armchair nanoribbons possess a\nhidden pseudovalley structure and effectively broken TRS. In contrast,\nsemiconducting armchair nanoribbons inevitably mix valleys and restore TRS. As\na result, in strong disorder metallic armchair ribbons exhibit a perfectly\nconducting channel, but semiconducting armchair ribbons ordinary localization.\nTRS is also effectively broken in zigzag nanoribbons in the absence of valley\nmixing. However, we show that intervalley scattering in zigzag ribbons is\nsignificantly enhanced and TRS is restored even for smooth disorder, if the\nFermi energy is smaller than the potential amplitude. The symmetry properties\nof disordered nanoribbons are also reflected in their conductance in the\ndiffusive regime. In particular, we find suppression of weak localization and\nan enhancement of conductance fluctuations in metallic armchair and zigzag\nribbons without valley mixing. In contrast, semiconducting armchair and zigzag\nribbons with valley mixing exhibit weak localization behavior."
    },
    {
        "anchor": "Spin-orbit induced spin-qubit control in nanowires: We elaborate on a number of issues concerning our recent proposal for\nspin-qubit manipulation in nanowires using the spin-orbit coupling. We discuss\nthe experimental status and describe in further detail the scheme for\nsingle-qubit rotations. We present a derivation of the effective two-qubit\ncoupling which can be extended to higher orders in the Coulomb interaction. The\nanalytic expression for the coupling strength is shown to agree with numerics.",
        "positive": "Cooperative Lifting of Spin Blockade in a Three-Terminal Triple Quantum\n  Dot: We report measurements of multi-path transport through a triple quantum dot\n(TQD) in the few-electron regime using a GaAs three-terminal device with a\nseparate lead attached to each dot. When two paths reside inside the transport\nwindow and are simultaneously spin-blockaded, the leak currents through both\npaths are significantly enhanced. We suggest that the transport processes in\nthe two paths cooperate to lift the spin blockade. Fine structures in transport\nspectra indicate that different kinds of cooperative mechanisms are involved,\ndepending on the details of the three-electron spin states governed by the size\nof exchange splitting relative to nuclear spin fluctuations. Our results\nindicate that a variety of correlation phenomena can be explored in\nthree-terminal TQDs."
    },
    {
        "anchor": "Electron charge and spin delocalization revealed in the optically probed\n  longitudinal and transverse spin dynamics in $n$-GaAs: The evolution of the electron spin dynamics as consequence of carrier\ndelocalization in $n$-type GaAs is investigated by the recently developed\nextended pump-probe Kerr/Faraday rotation spectroscopy. We find that isolated\nelectrons localized on donors demonstrate a prominent difference between the\nlongitudinal and transverse spin relaxation rates in magnetic field, which is\nalmost absent in the metallic phase. The inhomogeneous transverse dephasing\ntime $T_2^*$ of the spin ensemble strongly increases upon electron\ndelocalization as a result of motional narrowing that can be induced by\nincreasing either the donor concentration or the temperature. An unexpected\nrelation between $T_2^*$ and the longitudinal spin relaxation time $T_1$ is\nfound, namely that their product is about constant, as explained by the\nmagnetic field effect on the spin diffusion. We observe a two-stage\nlongitudinal spin relaxation which suggests the establishment of spin\ntemperature in the system of exchange-coupled donor-bound electrons.",
        "positive": "Charge-noise-insensitive gate operations for always-on, exchange-only\n  qubits: We introduce an always-on, exchange-only qubit made up of three localized\nsemiconductor spins that offers a true \"sweet spot\" to fluctuations of the\nquantum dot energy levels. Both single- and two-qubit gate operations can be\nperformed using only exchange pulses while maintaining this sweet spot. We show\nhow to interconvert this qubit to other three-spin encoded qubits as a new\nresource for quantum computation and communication."
    },
    {
        "anchor": "Spin effects in transport through single-molecule magnets in the\n  sequential and cotunneling regimes: We analyze the stationary spin-dependent transport through a single-molecule\nmagnet weakly coupled to external ferromagnetic leads. Using the real-time\ndiagrammatic technique, we calculate the sequential and cotunneling\ncontributions to current, tunnel magnetoresistance and Fano factor in both\nlinear and nonlinear response regimes. We show that the effects of cotunneling\nare predominantly visible in the blockade regime and lead to enhancement of\ntunnel magnetoresistance (TMR) above the Julliere value, which is accompanied\nwith super-Poissonian shot noise due to bunching of inelastic cotunneling\nprocesses through different virtual spin states of the molecule. The effects of\nexternal magnetic field and the role of type and strength of exchange\ninteraction between the LUMO level and the molecule's spin are also considered.\nWhen the exchange coupling is ferromagnetic, we find an enhanced TMR, while in\nthe case of antiferromagnetic coupling we predict a large negative TMR effect.",
        "positive": "Heisenberg-exchange-free nanoskyrmion mosaic: Isotropic Heisenberg exchange naturally appears as the main interaction in\nmagnetism, usually favouring long-range spin-ordered phases. The anisotropic\nDzyaloshinskii-Moriya interaction arises from relativistic corrections and is a\npriori much weaker, even though it may sufficiently compete with the isotropic\none to yield new spin textures. Here, we challenge this well-established\nparadigm, and propose to explore a Heisenberg-exchange-free magnetic world.\nThere, the Dzyaloshinskii-Moriya interaction induces magnetic frustration in\ntwo dimensions, from which the competition with an external magnetic field\nresults in a new mechanism producing skyrmions of nanoscale size. The isolated\nnanoskyrmion can already be stabilized in a few-atom cluster, and may then be\nused as LEGO block to build a large magnetic mosaic. The realization of such\ntopological spin nanotextures in sp- and p-electron compounds or in ultracold\natomic gases would open a new route toward robust and compact magnetic\nmemories."
    },
    {
        "anchor": "Investigating the current distribution of parallel-configured quantum\n  point contacts under quantum Hall conditions: Electric-field-controlled charge transport is a key concept of modern\ncomputers, embodied namely in field effect transistors. The metallic gate\nvoltage controls charge population, thus it is possible to define logical\nelements which are the key to computational processes. Here, we investigate a\nsimilar system defined by metallic gates inducing quasi-one-dimensional\ntransport channels on a high-mobility electron system in the presence of a\nstrong perpendicular magnetic field. Firstly, we solve the three-dimensional\nPoisson equation, self-consistently imposing relevant boundary conditions, and\nuse the output as an initial condition to calculate charge density and\npotential distribution in the plane of a two-dimensional electron system, in\nthe presence of an external magnetic field. Subsequently, we impose an external\ncurrent and obtain the spatial distribution of the transport charges,\nconsidering various magnetic field and gate voltage strengths at sufficiently\nlow (< 10 Kelvin) temperatures. We show that magnetic field breaks the spatial\nsymmetry of the current distribution, whereas voltage applied to metallic gates\ndetermines the scattering processes.",
        "positive": "Superconductor-semiconductor magnetic microswitch: A hybrid superconductor--two-dimensional electron gas microdevice is\npresented. Its working principle is based on the suppression of Andreev\nreflection at the superconductor-semiconductor interface caused by a magnetic\nbarrier generated by a ferromagnetic strip placed on top of the structure.\nDevice switching is predicted with fields up to some mT and working frequencies\nof several GHz, making it promising for applications ranging from microswitches\nand storage cells to magnetic field discriminators."
    },
    {
        "anchor": "Excitation of surface plasmon polariton modes with multiple nitrogen\n  vacancy centers in single nanodiamonds: Nitrogen-vacancy (NV) centers in diamonds are interesting due to their\nremarkable characteristics that are well suited to applications in\nquantum-information processing and magnetic field sensing, as well as\nrepresenting stable fluorescent sources. Multiple NV centers in nanodiamonds\n(NDs) are especially useful as biological fluorophores due to their chemical\nneutrality, brightness and room-temperature photostability. Furthermore, NDs\ncontaining multiple NV centers also have potential in high-precision magnetic\nfield and temperature sensing. Coupling NV centers to propagating surface\nplasmon polariton (SPP) modes gives a base for lab-on-a-chip sensing devices,\nallows enhanced fluorescence emission and collection which can further enhance\nthe precision of NV-based sensors. Here, we investigate coupling of multiple NV\ncenters in individual NDs to the SPP modes supported by silver surfaces\nprotected by thin dielectric layers and by gold V-grooves (VGs) produced via\nthe self-terminated silicon etching. In the first case, we concentrate on\nmonitoring differences in fluorescence spectra obtained from a source ND, which\nis illuminated by a pump laser, and from a scattering ND illuminated only by\nthe fluorescence-excited SPP radiation. In the second case, we observe changes\nin the average NV lifetime when the same ND is characterized outside and inside\na VG. Fluorescence emission from the VG terminations is also observed, which\nconfirms the NV coupling to the VG-supported SPP modes.",
        "positive": "Sideband cooling of nearly degenerate micromechanical oscillators in a\n  multimode optomechanical system: Multimode optomechanical systems are an emerging platform for studying\nfundamental aspects of matter near the quantum ground state and are useful in\nsensitive sensing and measurement applications. We study optomechanical cooling\nin a system where two nearly degenerate mechanical oscillators are coupled to a\nsingle microwave cavity. Due to an optically mediated coupling the two\noscillators hybridize into a bright mode with strong optomechanical cooling\nrate and a dark mode nearly decoupled from the system. We find that at high\ncoupling, sideband cooling of the dark mode is strongly suppressed. Our results\nare relevant to novel optomechanical systems where multiple closely-spaced\nmodes are intrinsically present."
    },
    {
        "anchor": "Measurement of the electronic compressibility of bilayer graphene: We present measurements of the electronic compressibility, $K$, of bilayer\ngraphene in both zero and finite magnetic fields up to 14 T, and as a function\nof both the carrier density and electric field perpendicular to the graphene\nsheet. The low energy hyperbolic band structure of bilayer graphene is clearly\nrevealed in the data, as well as a sizable asymmetry between the conduction and\nvalence bands. A sharp increase in $K^{-1}$ near zero density is observed for\nincreasing electric field strength, signaling the controlled opening of a gap\nbetween these bands. At high magnetic fields, broad Landau level (LL)\noscillations are observed, directly revealing the doubled degeneracy of the\nlowest LL and allowing for a determination of the disorder broadening of the\nlevels.",
        "positive": "Interaction Induced Restoration of Phase Coherence: We study the conductance of a quantum T-junction coupled to two electron\nreservoirs and a quantum dot. In the absence of electron-electron interactions,\nthe conductance $g$ is sensitive to interference between trajectories which\nenter the dot and those which bypass it. We show that including an intra-dot\ncharging interaction has a marked influence-- it can enforce a coherent\nresponse from the dot at temperatures much larger than the single particle\nlevel spacing $\\Delta$. The result is large oscillations of $g$ as a function\nof the voltage applied to a gate capacitively coupled to the dot. Without\ninteractions, the conductance has only a weak interference signature when\n$T>\\Delta$."
    },
    {
        "anchor": "Thermodynamic properties of the 2+1-dimensional Dirac fermions with\n  broken time-reversal symmetry: We study the thermodynamic properties of the two-component $2+1$-dimensional\nmassive Dirac fermions in an external magnetic field. The broken time-reversal\nsymmetry results in the presence of a linear in the magnetic field part of the\nthermodynamic potential, while in the famous problem of Landau diamagnetism the\nleading field dependent term is quadratic in the field. Accordingly, the\nleading term of the explicitly calculated magnetization is anomalous, viz. it\nis independent of the strength of the magnetic field. The St\\v{r}eda formula is\nemployed to describe how the anomalous magnetization is related to the\nanomalous Hall effect.",
        "positive": "A Deformable Model for Magnetic Vortex Pinning: A two-parameter analytical model of the magnetic vortex in a thin disk of\nsoft magnetic material is constructed. The model is capable of describing the\nchange in evolution of net vortex state magnetization and of core position when\nthe vortex core interacts with a magnetic pinning site. The model employs a\npiecewise, physically continuous, magnetization distribution obtained by the\nmerger of two extensively used one-parameter analytical models of the vortex\nstate in a disk. Through comparison to numerical simulations of ideal disks\nwith and without pinning sites, the model is found to accurately predict the\nmagnetization, vortex position, hysteretic transitions, and 2-D displacement of\nthe vortex in the presence of pinning sites. The model will be applicable to\nthe quantitative determination of vortex pinning energies from measurements of\nmagnetization."
    },
    {
        "anchor": "Spin and charge transport induced by gauge fields in a ferromagnet: We present a microscopic theory of spin-dependent motive force (\"spin motive\nforce\") induced by magnetization dynamics in a conducting ferromagnet, by\ntaking account of spin relaxation of conduction electrons. The theory is\ndeveloped by calculating spin and charge transport driven by two kinds of gauge\nfields; one is the ordinary electromagnetic field $A^{\\rm em}_{\\mu}$, and the\nother is the effective gauge field $A^{z}_{\\mu}$ induced by dynamical magnetic\ntexture. The latter acts in the spin channel and gives rise to a spin motive\nforce. It is found that the current induced as a linear response to\n$A^{z}_{\\mu}$ is not gauge-invariant in the presence of spin-flip processes.\nThis fact is intimately related to the non-conservation of spin via Onsager\nreciprocity, so is robust, but indicates a theoretical inconsistency. This\nproblem is resolved by considering the time dependence of spin-relaxation\nsource terms in the \"rotated frame\", as in the previous study on Gilbert\ndamping [J. Phys. Soc. Jpn. {\\bf 76}, 063710 (2007)]. This effect restores the\ngauge invariance while keeping spin non-conservation. It also gives a\ndissipative spin motive force expected as a reciprocal to the dissipative spin\ntorque (\"$\\beta$-term\").",
        "positive": "Cross correlations in mesoscopic charge detection: We study a tunnel contact that acts as charge detector for a single-electron\ntransistor (SET) focusing on correlations between the detector current and the\ncurrent through the SET. This system can be described fully by a Markovian\nmaster equation for the SET, while electron tunneling in the charge monitor\nrepresents a process with a stochastic rate, which can be solved exactly. It\nturns out that current monitoring is possible as long as the detector current\ncorrelates with the currents through either SET barrier. By contrast,\ncorrelations with the effective current according to the Ramo-Shockley theorem\nare not essential. Moreover, we propose the measurement of the SET barrier\ncapacitances."
    },
    {
        "anchor": "Angular X-ray Cross-Correlation Analysis Applied to the Scattering Data\n  in 3D Reciprocal Space from a Single Crystal: We propose an application of the Angular X-ray Cross-Correlation Analysis\n(AXCCA) to the scattered intensity distribution measured in three-dimensional\n(3D) reciprocal space from a single crystalline sample. Contrary to the\nconventional application of AXCCA, when averaging over many two-dimensional\n(2D) diffraction patterns collected from different randomly oriented samples is\nrequired, the proposed approach gives an insight into the structure of a single\nspecimen. This is particularly useful in studies of defect-reach samples that\nare unlikely to have the same structure. Here, we demonstrate an example of a\nqualitative structure determination of a colloidal crystal on the simulated as\nwell as experimentally measured 3D scattered intensity distributions.",
        "positive": "Seeing topological edge and bulk currents in time-of-flight images: Here we provide a general methodology to directly measure the topological\ncurrents emerging in the optical lattice implementation of the Haldane model.\nAlongside the edge currents supported by gapless edge states, transverse\ncurrents can emerge in the bulk of the system whenever the local potential is\nvaried in space, even if it does not cause a phase transition. In optical\nlattice implementations the overall harmonic potential that traps the atoms\nprovides the boundaries of the topological phase that supports the edge\ncurrents, as well as providing the potential gradient across the topological\nphase that gives rise to the bulk current. Both the edge and bulk currents are\nresilient to several experimental parameters such as trapping potential,\ntemperature and disorder. We propose to investigate the properties of these\ncurrents directly from time-of-flight images with both short-time and long-time\nexpansions."
    },
    {
        "anchor": "Coupled qubits as a quantum heat switch: We present a quantum heat switch based on coupled superconducting qubits,\nconnected to two $LC$ resonators that are terminated by resistors providing two\nheat baths. To describe the system we use a standard second order master\nequation with respect to coupling to the baths. We find that this system can\nact as an efficient heat switch controlled by the applied magnetic flux. The\nflux influences the energy level separations of the system, and under some\nconditions, the finite coupling of the qubits enhances the transmitted power\nbetween the two baths, by an order of magnitude under realistic conditions. At\nthe same time, the bandwidth at maximum power of the switch formed of the\ncoupled qubits is narrowed.",
        "positive": "Quantum LC - circuits with diffusive modification of the continuity\n  equation: Proofs are given that the quantum-mechanical description of the LC-circuit\nwith a time dependent external source can be readily established by starting\nfrom a general discretization rule of the electric charge. For this purpose one\nresorts to an arbitrary but integer-dependent real function F(n) instead of n.\nThis results in a nontrivial generalization of the discrete time dependent\nSchrodinger-equation established before via F(n)=n. Such generalization leads\nto site-dependent hopping amplitudes as well as to diffusive modification of\nthe continuity equation. One shows, in particular, that there are firm supports\nconcerning rational multiples of the elementary electric charge."
    },
    {
        "anchor": "Robust integer and fractional helical modes in the quantum Hall effect: Electronic systems harboring one dimensional helical modes, where the spin\nand momentum of the electron are locked, have lately become an important field\nof its own. When coupled to a conventional superconductor, such systems are\nexpected to manifest topological superconductivity, a unique phase that gives\nrise to exotic Majorana zero modes. Even more interesting are fractional\nhelical states which have not been observed before and which open the route for\nthe realization of the generalized para fermions quasiparticles. Possessing non\nabelian exchange statistics, these quasiparticles may serve as building blocks\nin topological quantum computing. Here, we present a new approach to form\nprotected one dimensional helical and fractional helical edge modes in the\nquantum Hall regime. The novel platform is based on a carefully designed double\nquantum well structure in a high mobility GaAs based system. In turn, the\nquantum well hosts two sub bands of 2D electrons, each tuned to the quantum\nHall effect regime. By electrostatic gating of different areas of the\nstructure, counter propagating integer, as well as fractional, edge modes,\nbelonging to Landau levels with opposite spins are formed, rendering the modes\nhelical. We demonstrate that due to spin protection, these helical modes remain\nballistic, without observed mixing for large distances. In addition to the\nformation of helical modes, this new platform can be exploited as a rich\nplayground for an artificial induction of compounded fractional edge modes, as\nwell as construction of interferometers based on chiral edge modes.",
        "positive": "Manipulation of Topological States and Bulk Band Gap Using Natural\n  Heterostructures of a Topological Insulator: We have performed angle-resolved photoemission spectroscopy on\n(PbSe)5(Bi2Se3)3m, which forms a natural multilayer heterostructure consisting\nof a topological insulator (TI) and an ordinary insulator. For m = 2, we\nobserved a gapped Dirac-cone state within the bulk-band gap, suggesting that\nthe topological interface states are effectively encapsulated by block layers;\nfurthermore, it was found that the quantum confinement effect of the band\ndispersions of Bi2Se3 layers enhances the effective bulk-band gap to 0.5 eV,\nthe largest ever observed in TIs. In addition, we found that the system is no\nlonger in the topological phase at m = 1, pointing to a topological phase\ntransition between m = 1 and 2. These results demonstrate that utilization of\nnaturally-occurring heterostructures is a new promising strategy for realizing\nexotic quantum phenomena and device applications of TIs."
    },
    {
        "anchor": "Universal properties of boundary and interface charges in multichannel\n  one-dimensional continuum models: We generalize our recent results for the boundary and interface charges in\none-dimensional single-channel continuum [Phys. Rev. B 104, 155409 (2021)] and\nmultichannel tight-binding [Phys. Rev. B 104, 125447 (2021)] models to the\nrealm of the multichannel continuum systems. Using the technique of boundary\nGreen's functions, we give a rigorous proof that the change in boundary charge\nupon the shift of the system towards the boundary by the distance\n$x_{\\varphi}\\in[0, L]$ is given by a perfectly linear function of $x_{\\varphi}$\nplus an integer-valued topological invariant $I$ -- the so called boundary\ninvariant. For systems with weak potential amplitudes, we additionally develop\nGreen's function-based low-energy theory, allowing one to analytically access\nthe physics of multichannel continuum systems in the low-energy approximation.",
        "positive": "Conductance through quantum wires with Levy-type disorder: universal\n  statistics in anomalous quantum transport: In this letter we study the conductance G through one-dimensional quantum\nwires with disorder configurations characterized by long-tailed distributions\n(Levy-type disorder). We calculate analytically the conductance distribution\nwhich reveals a universal statistics: the distribution of conductances is fully\ndetermined by the exponent \\alpha of the power-law decay of the disorder\ndistribution and the average < ln G >, i.e., all other details of the disorder\nconfigurations are irrelevant. For 0< \\alpha < 1 we found that the fluctuations\nof ln G are not self-averaging and < ln G > scales with the length of the\nsystem as L^\\alpha, in contrast to the predictions of the standard\nscaling-theory of localization where ln G is a self-averaging quantity and < ln\nG > scales linearly with L. Our theoretical results are verified by comparing\nwith numerical simulations of one-dimensional disordered wires."
    },
    {
        "anchor": "Mechanisms for strong anisotropy of in-plane g-factors in hole based\n  quantum point contacts: In-plane hole g-factors measured in quantum point contacts based on p-type\nheterostructures strongly depend on the orientation of the magnetic field with\nrespect to the electric current. This effect, first reported a decade ago and\nconfirmed in a number of publications, has remained an open problem. In this\nwork, we present systematic experimental studies to disentangle different\nmechanisms contributing to the effect and develop the theory which describes it\nsuccessfully. We show that there is a new mechanism for the anisotropy related\nto the existence of an additional $B_+k_-^4\\sigma_+$ effective Zeeman\ninteraction for holes, which is kinematically different from the standard\nsingle Zeeman term $B_-k_-^2\\sigma_+$ considered until now.",
        "positive": "Topological aspects of periodically driven non-Hermitian\n  Su-Schrieffer-Heeger model: A non-Hermitian generalization of the Su-Schrieffer-Heeger model driven by a\nperiodic external potential is investigated, and its topological features are\nexplored. We find that the bi-orthonormal geometric phase acts as a topological\nindex, well capturing the presence/absence of the zero modes. The model is\nobserved to display trivial and non-trivial insulator phases and a\ntopologically non-trivial M${\\\"o}$bius metallic phase. The driving field\namplitude is shown to be a control parameter causing topological phase\ntransitions in this model. While the system displays zero modes in the metallic\nphase apart from the non-trivial insulator phase, the metallic zero modes are\nnot robust, as the ones found in the insulating phase. We further find that\nzero modes' energy converges slowly to zero as a function of the number of\ndimers in the M${\\\"o}$bius metallic phase compared to the non-trivial\ninsulating phase."
    },
    {
        "anchor": "Voltage drop across Josephson junctions for L\u00e9vy noise detection: We propose to characterize L\\'evy-distributed stochastic fluctuations through\nthe measurement of the average voltage drop across a current-biased Josephson\njunction. We show that the noise induced switching process in the Josephson\nwashboard potential can be exploited to reveal and characterize L\\'evy\nfluctuations, also if embedded in a thermal noisy background. The measurement\nof the average voltage drop as a function of the noise intensity allows to\ninfer the value of the stability index that characterizes L\\'evy-distributed\nfluctuations. An analytical estimate of the average velocity in the case of a\nL\\'evy-driven escape process from a metastable state well agrees with the\nnumerical calculation of the average voltage drop across the junction. The best\nperformances are reached at small bias currents and low temperatures,\n\\emph{i.e.}, when both thermally activated and quantum tunneling switching\nprocesses can be neglected. The effects discussed in this work pave the way\ntoward an effective and reliable method to characterize L\\'evy components\neventually present in an unknown noisy signal.",
        "positive": "Quantized Nonlinear Conductance in Ballistic Metals: We introduce a non-linear frequency dependent D+1 terminal conductance that\ncharacterizes a D dimensional Fermi gas, generalizing the Landauer conductance\nin D=1. For a 2D ballistic conductor we show that this conductance is quantized\nand probes the Euler characteristic of the Fermi sea. We critically address the\nroles of electrical contacts and of Fermi liquid interactions, and we propose\nexperiments on 2D Dirac materials such as graphene using a triple point contact\ngeometry."
    },
    {
        "anchor": "Unified Theory of the Anomalous and Topological Hall Effects with Phase\n  Space Berry Curvatures: Hall experiments in chiral magnets are often analyzed as the sum of an\nanomalous Hall effect, dominated by momentum-space Berry curvature, and a\ntopological Hall effect, arising from the real-space Berry curvature in the\npresence of skyrmions, in addition to the ordinary Hall resistivity. This\nraises the questions of how one can incorporate, on an equal footing, the\neffects of the anomalous velocity and the real space winding of the\nmagnetization, and when such a decomposition of the resistivity is justified.\nWe provide definitive answers to these questions by including the effects of\nall phase-space Berry curvatures in a semi-classical approach and by solving\nthe Boltzmann equation in a weak spin-orbit coupling regime when the\nmagnetization texture varies slowly on the scale of the mean free path. We show\nthat the Hall resistivity is then just the sum of the anomalous and topological\ncontributions, with negligible corrections from Berry curvature-independent and\nmixed curvature terms. We also use an exact Kubo formalism to numerically\ninvestigate the opposite limit of infinite mean path, and show that the results\nare similar to the semi-classical results.",
        "positive": "Anamolous conductance plateau in an asymmetrically biased InAs/InAlAs\n  quantum point contact: The appearance and evolution of an anomalous conductance plateau at 0.4 (in\nunits of 2e2/h) in an In0.52Al0.48As/InAs quantum point contact (QPC), in the\npresence of lateral spin-orbit coupling, has been studied at T=4.2K as a\nfunction of the potential asymmetry between the in-plane gates of the QPC. The\nanomalous plateau, a signature of spin polarization in the channel, appears\nonly over an intermediate range (around 3 V) of bias asymmetry. It is quite\nrobust, being observed over a maximum range of nearly 1V of the sweep voltage\ncommon to the two in-plane gates. Our conductance measurements show evidence of\nsurface roughness scattering from the side walls of the QPC. We show that a\nstrong perpendicular magnetic field leads to magnetic confinement in the\nchannel which reduces the importance of scattering from the side walls and\nfavors the onset of near ballistic transport through the QPC."
    },
    {
        "anchor": "Topological staggered field-electric effect with bipartite magnets: We study the interface physics of bipartite magnetic materials deposited on a\ntopological insulator. This comprises antiferromagnets as well as ferrimagnets\nand ferromagnets with multiple magnetic moments per unit cell. If an energy gap\nis induced in the Dirac states on the topological surface, a topological\nmagnetoelectric effect has been predicted. Here, we show that this effect can\nact in opposite directions on the two components of the magnet in certain\nparameter regions. Consequently, an electric field will mainly generate a\nstaggered field rather than a net magnetization in the plane. This is relevant\nfor the current attempts to detect the magnetoelectric effect experimentally,\nas well as for possible applications. We take a field-theoretic approach that\nincludes the quantum fluctuations of both the Dirac fermions on the topological\nsurface as well as the fermions in the surface layer of the magnet in an\nanalytically solvable model. The effective Lagrangian and the Landau-Lifshitz\nequation describing the interfacial magnetization dynamics are derived.",
        "positive": "Dispersion relation, propagation length and mode conversion of surface\n  plasmon polaritons in silver double-nanowire systems: We study the surface plasmon modes in a silver double-nanowire system by\nemploying the eigenmode analysis approach based on the finite element method.\nCalculated dispersion relations, surface charge distributions, field patterns\nand propagation lengths of ten lowest energy plasmon modes in the system are\npresented. These ten modes are categorized into three groups because they are\nfound to originate from the monopole-monopole, dipole-dipole and\nquadrupole-quadrupole hybridizations between the two wires, respectively.\nInterestingly, in addition to the well studied gap mode (mode 1), the other\nmode from group 1 which is a symmetrically coupled charge mode (mode 2) is\nfound to have a larger group velocity and a longer propagation length than mode\n1, suggesting mode 2 to be another potential signal transporter for plasmonic\ncircuits. Scenarios to efficiently excite (inject) group 1 modes in the\ntwo-wire system and also to convert mode 2 (mode 1) to mode 1 (mode 2) are\ndemonstrated by numerical simulations."
    },
    {
        "anchor": "Effective Time Reversal Symmetry Breaking and Energy Spectra of Graphene\n  Armchair Rings: We study the energy spectra and wavefunctions of graphene rings formed from\nmetallic armchair ribbons, near zero energy, to search for properties which may\nbe identified with \"effective broken time reversal symmetry\" (EBTRS).\nAppropriately chosen corner junctions are shown to impose phase shifts in the\nwavefunctions that at low energies have the same effect as effective flux tubes\npassing near the ribbon surface. Closing the ribbon into a ring captures this\nflux and yields properties that may be understood as signatures of EBTRS. These\ninclude a gap in the spectrum around zero energy, which can be removed by the\napplication of real magnetic flux through the ring. Spectra of five and seven\nsided rings are also examined, and it is shown these do not have particle-hole\nsymmetry, which may also be understood as a consequence of EBTRS, and is\nconnected to the curvature induced in the system when such rings are formed.\nEffects of deviations from the ideal geometries on the spectra are also\nexamined.",
        "positive": "Growth Process of Hexagonal Boron Nitride in the Diffusion and\n  Precipitation Method Studied by X-ray Photoelectron Spectroscopy: Submonolayer h-BN was grown on Ni foil in ultra-high vacuum by the diffusion\nand precipitation method and the growth process was studied by x-ray\nphotoelectron spectroscopy. Formation of h-BN started to be observed at 600 C.\nAll through the process, the surface was always slightly B-rich, which is\nconsistent with the fact that B which is soluble in Ni at a high temperature\ncan diffuse in Ni by the conventional bulk diffusion and insoluble N cannot.\nMoreover, both formation and decomposition of h-BN were found to occur at\nelevated temperatures possibly depending on provision of N atoms to the\nsurface. On the Ni surface, decomposition of h-BN was observed at a relatively\nlow temperature of 800 C."
    },
    {
        "anchor": "Encoding information onto the charge and spin state of a paramagnetic\n  atom using MgO tunnelling spintronics: An electrical current that flows across individual atoms or molecules can\ngenerate exotic quantum-based behavior, from memristive effects to Coulomb\nblockade and the promotion of quantum excited states. These fundamental effects\ntypically appear one at a time in model junctions built using atomic tip or\nlateral techniques. So far, however, a viable industrial pathway for such\ndiscrete state devices has been lacking. Here, we demonstrate that a\ncommercialized device platform can serve as this industrial pathway for quantum\ntechnologies. We have studied magnetic tunnel junctions with a MgO barrier\ncontaining C atoms. The paramagnetic localized electrons due to individual C\natoms generate parallel nanotransport paths across the micronic device as\ndeduced from magnetotransport experiments. Coulomb blockade effects linked to\ntunnelling magnetoresistance peaks can be electrically controlled, leading to a\npersistent memory effect. Our results position MgO tunneling spintronics as a\npromising platform to industrially implement quantum technologies.",
        "positive": "Circuit Quantum Simulation of a Tomonaga-Luttinger Liquid with an\n  Impurity: The Tomonaga-Luttinger liquid (TLL) concept is believed to generically\ndescribe the strongly-correlated physics of one-dimensional systems at low\ntemperatures. A hallmark signature in 1D conductors is the quantum phase\ntransition between metallic and insulating states induced by a single impurity.\nHowever, this transition impedes experimental explorations of real-world TLLs.\nFurthermore, its theoretical treatment, explaining the universal energy\nrescaling of the conductance at low temperatures, has so far been achieved\nexactly only for specific interaction strengths. Quantum simulation can provide\na powerful workaround. Here, a hybrid metal-semiconductor dissipative quantum\ncircuit is shown to implement the analogue of a TLL of adjustable electronic\ninteractions comprising a single, fully tunable scattering impurity.\nMeasurements reveal the renormalization group `beta-function' for the\nconductance that completely determines the TLL universal crossover to an\ninsulating state upon cooling. Moreover, the characteristic scaling energy\nlocating at a given temperature the position within this conductance\nrenormalization flow is established over nine decades versus circuit\nparameters, and the out-of-equilibrium regime is explored. With the quantum\nsimulator quality demonstrated from the precise parameter-free validation of\nexisting and novel TLL predictions, quantum simulation is achieved in a strong\nsense, by elucidating interaction regimes which resist theoretical solutions."
    },
    {
        "anchor": "Robust mutual synchronization in long spin Hall nano-oscillator chains: Mutual synchronization of N serially connected spintronic nano-oscillators\nincreases their coherence by a factor $N$ and their output power by $N^2$.\nIncreasing the number of mutually synchronized nano-oscillators in chains is\nhence of great importance for better signal quality and also for emerging\napplications such as oscillator-based neuromorphic computing and Ising machines\nwhere larger N can tackle larger problems. Here we fabricate spin Hall\nnano-oscillator chains of up to 50 serially connected nano-constrictions in\nW/NiFe, W/CoFeB/MgO, and NiFe/Pt stacks and demonstrate robust and complete\nmutual synchronization of up to 21 nano-constrictions, reaching linewidths of\nbelow 200 kHz and quality factors beyond 79,000, while operating at 10 GHz. We\nalso find a square increase in the peak power with the increasing number of\nmutually synchronized oscillators, resulting in a factor of 400 higher peak\npower in long chains compared to individual nano-constrictions. Although chains\nlonger than 21 nano-constrictions also show complete mutual synchronization, it\nis not as robust and their signal quality does not improve as much as they\nprefer to break up into partially synchronized states. The low current and low\nfield operation of these oscillators along with their wide frequency tunability\n(2-28 GHz) with both current and magnetic fields, make them ideal candidates\nfor on-chip GHz-range applications and neuromorphic computing.",
        "positive": "Boosting proximity spin orbit coupling in graphene/WSe$_2$\n  heterostructures via hydrostatic pressure: Van der Waals heterostructures composed of multiple few layer crystals allow\nthe engineering of novel materials with predefined properties. As an example,\ncoupling graphene weakly to materials with large spin orbit coupling (SOC)\nallows to engineer a sizeable SOC in graphene via proximity effects. The\nstrength of the proximity effect depends on the overlap of the atomic orbitals,\ntherefore, changing the interlayer distance via hydrostatic pressure can be\nutilized to enhance the interlayer coupling between the layers. In this work,\nwe report measurements on a graphene/WSe$_2$ heterostructure exposed to\nincreasing hydrostatic pressure. A clear transition from weak localization to\nweak anti-localization is visible as the pressure increases, demonstrating the\nincrease of induced SOC in graphene."
    },
    {
        "anchor": "Dynamic Phase Diagram of an Orthogonal Spin Torque device: Topological\n  Category: The magnetization evolution of the free layer in an orthogonal spin-torque\ndevice is studied based on a macrospin model. The trajectory of magnetization\nvector under various conditions has shown rich nonlinear properties. The phase\ndiagram is obtained in the parameter spaces of current density and the\npolarization distribution (the ratio of in-plane and out-of-plane polarizers).\nThese dynamic phases can be classified according to their nonlinear behaviors\nwhich are topologically different, namely limit point and/or limit cycle. The\ntopological classification is meaningful to design the ultra-fast spin-torque\ndevices under different dynamic conditions towards various applications such as\nmemory and oscillators.",
        "positive": "Phase diagrams for quantum Brownian motion models on two-dimensional\n  Bravais lattices: We study quantum Brownian motion (QBM) models for a particle in a dissipative\nenvironment coupled to a periodic potential. We review QBM for a particle in a\none-dimensional periodic potential and extend the study to that for a particle\nin two-dimensional (2D) periodic potentials of four Bravais lattice types:\nsquare, rectangular, triangular (hexagonal), and centered rectangular. We\nperform perturbative renormalization group analyses to derive the zero\ntemperature flow diagrams and phase boundaries for a particle in these\npotentials, and observe localization behavior dependent on the anisotropy of\nthe lattice parameters."
    },
    {
        "anchor": "Antiferromagnetic ordering in van der Waals two-dimensional magnetic\n  material MnPS3 probed by Raman spectroscopy: Magnetic ordering in the two-dimensional limit has been one of the most\nimportant issues in condensed matter physics for the past several decades. The\nrecent discovery of new magnetic van der Waals materials heralds a much-needed\neasy route for the studies of two-dimensional magnetism: the thickness\ndependence of the magnetic ordering has been examined by using Ising- and\nXXZ-type magnetic van der Waals materials. Here, we investigated the magnetic\nordering of MnPS3, a two-dimensional antiferromagnetic material of\nHeisenberg-type, by Raman spectroscopy from bulk all the way down to bilayer.\nThe phonon modes that involve the vibrations of Mn ions exhibit characteristic\nchanges as the temperature gets lowered through the N\\'eel temperature. In bulk\nMnPS3, the Raman peak at ~155 cm-1 becomes considerably broadened near the\nN\\'eel temperature and upon further cooling is subsequently red-shifted. The\nmeasured peak positions and polarization dependences of the Raman spectra are\nin excellent agreement with our first-principles calculations. In few-layer\nMnPS3, the peak at ~155 cm-1 exhibits the characteristic red-shift at low\ntemperatures down to the bilayer, indicating that the magnetic ordering is\nsurprisingly stable at such a thin limit. Our work sheds light on the hitherto\nunexplored magnetic ordering in the Heisenberg-type antiferromagnetic systems\nin the atomic-layer limit.",
        "positive": "Identifying signatures of photothermal current in a double-gated\n  semiconducting nanotube: The remarkable electrical and optical properties or single-walled carbon\nnanotubes (SWNT) allowed for engineering device prototypes showing great\npotential for applications such as photodectors and solar cells. However, any\npath towards industrial maturity requires a detailed understanding of the\nfundamental mechanisms governing the process of photocurrent generation. Here,\nwe present scanning photocurrent microscopy measurements on a double-gated\nsuspended semiconducting SWNT and show that both photovoltaic and photothermal\nmechanisms are relevant for the interpretation of the photocurrent. We find\nthat the dominant or non-dominant character of one or the other processes\ndepends on the doping profile, and that the magnitude of each contribution is\nstrongly influenced by the series resistance from the band alignment with the\nmetal contacts. These results provide new insight into the interpretation of\nfeatures in scanning photocurrent microscopy and lay the foundation for the\nunderstanding of optoelectronic devices made from SWNTs."
    },
    {
        "anchor": "Polariton interactions in microcavities with atomically thin\n  semiconductor layers: We investigate the interactions between exciton-polaritons in N\ntwo-dimensional semiconductor layers embedded in a planar microcavity. In the\nlimit of low-energy scattering, where we can ignore the composite nature of the\nexcitons, we obtain exact analytical expressions for the spin-triplet and\nspin-singlet interaction strengths, which go beyond the Born approximation\nemployed in previous calculations. Crucially, we find that the strong\nlight-matter coupling enhances the strength of polariton-polariton interactions\ncompared to that of the exciton-exciton interactions, due to the Rabi coupling\nand the small photon-exciton mass ratio. We furthermore obtain the dependence\nof the polariton interactions on the number of layers N, and we highlight the\nimportant role played by the optically dark states that exist in multiple\nlayers. In particular, we predict that the singlet interaction strength is\nstronger than the triplet one for a wide range of parameters in most of the\ncurrently used transition metal dichalcogenides. This has consequences for the\npursuit of polariton condensation and other interaction-driven phenomena in\nthese materials.",
        "positive": "Resolving and Tuning Carrier Capture Rates at a Single Silicon Atom Gap\n  State: We report on tuning the carrier capture events at a single dangling bond (DB)\nmidgap state by varying the substrate temperature, doping type, and doping\nconcentration. All-electronic time-resolved scanning tunneling microscopy\n(TR-STM) is employed to directly measure the carrier capture rates on the\nnanosecond time scale. A characteristic negative differential resistance (NDR)\nfeature is evident in the scanning tunneling microscopy (STM) and scanning\ntunneling spectroscopy (STS) measurements of DBs on both n and p-type doped\nsamples. It is found that a common model accounts for both observations.\nAtom-specific Kelvin probe force microscopy (KPFM) measurements confirm the\nenergetic position of the DB's charge transition levels, corroborating STS\nstudies. It is shown that under different tip-induced fields the DB can be\nsupplied from two distinct reservoirs: the bulk conduction band and/or the\nvalence band. We measure the filling and emptying rates of the DBs in the\nenergy regime where electrons are supplied by the bulk valence band. By adding\npoint charges in the vicinity of a DB, Coulombic interactions are shown to\nshift observed STS and NDR features."
    },
    {
        "anchor": "Optical initialization, readout and dynamics of a Mn spin in a quantum\n  dot: We have investigated the spin preparation efficiency by optical pumping of\nindividual Mn atoms embedded in CdTe/ZnTe quantum dots. Monitoring the time\ndependence of the intensity of the fluorescence during the resonant optical\npumping process in individual quantum dots allows to directly probe the\ndynamics of the initialization of the Mn spin. This technique presents the\nconvenience of including preparation and read-out of the Mn spin in the same\nstep. Our measurements demonstrate that Mn spin initialization, at zero\nmagnetic field, can reach an efficiency of 75% and occurs in the tens of\n\\emph{ns} range when a laser resonantly drives at saturation one of the quantum\ndot transition. We observe that the efficiency of optical pumping changes from\ndot to dot and is affected by a magnetic field of a few tens of mT applied in\nVoigt or Faraday configuration. This is attributed to the local strain\ndistribution at the Mn location which predominantly determines the dynamics of\nthe Mn spin under weak magnetic field. The spectral distribution of the\nspin-flip scattered photons from quantum dots presenting a weak optical pumping\nefficiency reveals a significant spin relaxation for the exciton split in the\nexchange field of the Mn spin.",
        "positive": "Direct and inverse spin Hall effect: Lorentz force and Zeeman energy: It is shown that magnetic forces as the Lorentz force, exerted on electric\ncurrents, and the force {\\mu}Div(B), exerted on electron spins at rest, account\nfor both the transverse spin imbalance typical of spin Hall effect and the\ntransverse charge imbalance associated with pure spin currents (inverse spin\nHall effect). Considering that for stationary currents the laboratory reference\nframe and those for which the spin up and spin down carriers are at rest are\ninertial systems, one can easily find the forces exerted by the lattice on both\nspin sub-bands, as well as the force between sub-bands."
    },
    {
        "anchor": "Thermally driven two-magnet nano-oscillator with large spin-charge\n  conversion: Next-generation spintronic applications require material properties that can\nbe hardly met by one material candidate. Here we demonstrate that by combining\ninsulating and metallic magnets, enhanced spin-charge conversion and\nenergy-efficient thermal spin currents can be realized. We develop a nanowire\ndevice consisting of an yttrium iron garnet and permalloy bi-layer. An\ninterfacial temperature gradient drives the nanowire magnetization into\nauto-oscillations at gigahertz frequencies. Interfacial spin coupling and\nmagnetoresistance of the permalloy layer translate spin dynamics into sizable\nmicrowave signals. The results show prospect for energy-efficient spintronic\ndevices and present an experimental realization of magnon condensation in a\nheterogeneous magnetic system.",
        "positive": "Enhanced Multiple Exciton Generation in Amorphous Silicon Nanoparticles: Multiple exciton generation (MEG) in nanometer-sized hydrogen-passivated\nsilicon nanowires (NWs), and quasi two-dimensional nanofilms strongly depends\non the degree of the core structural disorder as shown by the many-body\nperturbation theory (MBPT) calculations based on the density functional theory\n(DFT) simulations. Working to the second order in the electron-photon coupling\nand in the screened Coulomb interaction we calculate quantum efficiency (QE),\nthe average number of excitons created by a single absorbed photon, in the\n${\\rm Si}_{29}{\\rm H}_{36}$ quantum dots (QDs) with crystalline and amorphous\ncore structures, simple cubic three-dimensional arrays constructed from these\nQDs, crystalline and amorphous NWs, and quasi two-dimensional silicon\nnanofilms, also both crystalline and amorphous. Efficient MEG with QE of 1.3 up\nto 1.8 at the photon energy of about $3E_g$, where $E_g$ is the electronic gap,\nis predicted in these nanoparticles except for the crystalline NW and\ncrystalline film where $QE\\simeq 1.$ MEG in the amorphous nanoparticles is\nenhanced by the electron localization due to structural disorder. Combined with\nthe lower gaps, the nanometer-sized amorphous silicon NWs and films are\npredicted to have effective carrier multiplication within the solar spectrum\nrange."
    },
    {
        "anchor": "Fabrication and characterization of an induced GaAs single hole\n  transistor: We have fabricated and characterized a single hole transistor in an undoped\nAlGaAs-GaAs heterostructure. Our device consists of a p-type quantum dot,\npopulated using an electric field rather than modulation doping. Low\ntemperature transport measurements reveal periodic conductance oscillations due\nto Coulomb blockade. We find that the low frequency charge noise is comparable\nto that in modulation-doped GaAs single electron transistors (SETs), and almost\nan order of magnitude better than in silicon SETs.",
        "positive": "Higgs amplitude mode in ballistic superconducting hybrid junctions: In superconductors (SC), the Higgs amplitude mode is a coherent oscillation\nof the order parameter typically generated by THz laser irradiation. In this\npaper we propose to probe the Higgs mode using electronic transport in\nballistic superconducting hybrid devices. We first confirm the existence of a\nnon-zero amplitude mode in the clean case using the Keldysh-Eilenberger\nformalism. We then investigate two different geometries, respectively a\nnormal-insulating-superconductor (NIS) tunnel junction and a NSN junction with\ntransparent interfaces, the superconductor being irradiated in both situations.\nIn the NIS case, the Higgs manifests itself in the second-order AC current\nresponse which is resonant at the Higgs frequency. In the NSN case, the DC\ndifferential conductance allows to probe the gaps generated by the Higgs mode\nin the Floquet spectrum."
    },
    {
        "anchor": "Bulk-LDOS Correspondence in Topological Insulators: Seeking the criterion for diagnosing topological phases in real materials has\nbeen one of the major tasks in topological physics. Currently, bulk-boundary\ncorrespondence based on spectral measurements of in gap topological boundary\nstates and the fractional corner anomaly derived from the measurement of the\nfractional spectral charge are two main approaches to characterize\ntopologically insulating phases. However, these two methods require a complete\nband-gap with either in-gap states or strict spatial symmetry of the overall\nsample which significantly limits their applications to more generalized cases.\nHere we propose and demonstrate an approach to link the non-trivial\nhierarchical bulk topology to the multidimensional partition of local-density\nof states (LDOS) respectively, denoted as the bulk-LDOS correspondence.\nSpecifically, in a finite-size topologically nontrivial photonic crystal, we\nobserve that the distribution of LDOS is divided into three partitioned regions\nof the sample - the two-dimensional interior bulk area (avoiding edge and\ncorner areas), one-dimensional edge region (avoiding the corner area), and\nzero-dimensional corner sites. In contrast, the LDOS is distributed across the\nentire two-dimensional bulk area across the whole spectrum for the\ntopologically trivial cases. Moreover, we present the universality of this\ncriterion by validating this correspondence in both a higher-order topological\ninsulator without a complete band gap and with disorders. Our findings provide\na general way to distinguish topological insulators and unveil the unexplored\nfeatures of topological directional band-gap materials without in-gap states.",
        "positive": "Femtosecond Thermal and Nonthermal Hot Electron Tunneling inside a\n  Photoexcited Tunnel Junction: Efficient operation of electronic nanodevices at ultrafast speeds requires\nunderstanding and control of the currents generated by femtosecond bursts of\nlight. Ultrafast laser-induced currents in metallic nanojunctions can originate\nfrom photo-assisted hot electron tunneling or lightwave-induced tunneling. Both\nprocesses can drive localized photocurrents inside a scanning tunneling\nmicroscope (STM) on femto- to attosecond time scales, enabling ultrafast STM\nwith atomic spatial resolution. Femtosecond laser excitation of a metallic\nnanojunction, however, also leads to the formation of a transient thermalized\nelectron distribution, but the tunneling of thermalized hot electrons on time\nscales faster than electron-lattice equilibration is not well understood. Here,\nwe investigate ultrafast electronic heating and transient thermionic tunneling\ninside a metallic photoexcited tunnel junction and its role in the generation\nof ultrafast photocurrents in STM. Phase-resolved sampling of broadband THz\npulses via the THz-field-induced modulation of ultrafast photocurrents allows\nus to probe the electronic temperature evolution inside the STM tip, and to\nobserve the competition between instantaneous and delayed tunneling due to\nnonthermal and thermal hot electron distributions in real time. Our results\nreveal the pronounced nonthermal character of photo-induced hot electron\ntunneling, and provide a detailed microscopic understanding of hot electron\ndynamics inside a laser-excited tunnel junction."
    },
    {
        "anchor": "Lithography-free Fabrication of High Quality Substrate-supported and\n  Freestanding Graphene devices: We present a lithography-free technique for fabrication of clean, high\nquality graphene devices. This technique is based on evaporation through hard\nSi shadow masks, and eliminates contaminants introduced by lithographical\nprocesses. We demonstrate that devices fabricated by this technique have\nsignificantly higher mobility values than those by standard electron beam\nlithography. To obtain ultra-high mobility devices, we extend this technique to\nfabricate suspended graphene samples with mobility as high as 120,000 cm^2/Vs.",
        "positive": "Thermodynamics of a generalized graphene-motivated (2+1)-dimensional\n  Gross-Neveu model beyond mean field within the Beth-Uhlenbeck approach: We investigate the thermodynamics at finite density of a generalized $(2 +\n1)$-dimensional Gross-Neveu model of $N$ fermion species with various types of\nfour-fermion interactions. The motivation for considering such a generalized\nschematic model arises from taking the Fierz-transformation of an effective\nCoulomb current-current interaction and certain symmetry breaking interaction\nterms, as considered for graphene-type models in Ref. [16]. We then apply\npath-integral bosonization techniques, based on the large $N$ limit, to derive\nthe thermodynamic potential. This includes the leading order mean-field (saddle\npoint) contribution as well as the next-order contribution of Gaussian\nfluctuations of exciton fields. The main focus of the paper is then the\ninvestigation of the thermodynamic properties of the resulting fermion-exciton\nplasma. In particular, we derive an extended Beth-Uhlenbeck form of the\nthermodynamic potential, discuss the Levinson theorem and the decomposition of\nthe phase of the exciton correlation into a resonant and scattering part."
    },
    {
        "anchor": "Single-particle subband structure of Quantum Cables: We proposed a model of Quantum Cable in analogy to the recently synthesized\ncoaxial nanocable structure [Suenaga et al. Science, 278, 653 (1997); Zhang et\nal. ibid, 281, 973 (1998)], and studied its single-electron subband structure.\nOur results show that the subband spectrum of Quantum Cable is different from\neither double-quantum-wire (DQW) structure in two-dimensional electron gas\n(2DEG) or single quantum cylinder. Besides the double degeneracy of subbands\narisen from the non-abelian mirrow reflection symmetry, interesting\nquasicrossings (accidental degeneracies), anticrossings and bundlings of\nQuantum Cable energy subbands are observed for some structure parameters. In\nthe extreme limit (barrier width tends to infinity), the normal degeneracy of\nsubbands different from the DQW structure is independent on the other structure\nparameters.",
        "positive": "The conductance of the quantum wire touching the gated Aharonov-Bohm\n  ring: We analyse the conductance of the Aharonov - Bohm (AB) one- dimensional\nquantum ring touching a quantum wire. The period of the AB oscillations is\nshown to be dependent strongly on the chemical potential and the Rashba\ncoupling parameter that is in a good agreement with the studies of such a\ndevice prepared on the Si(100) surface."
    },
    {
        "anchor": "Excitonic instability in transition metal dichalcogenides: When transition-metal dichalcogenide monolayers lack inversion symmetry,\ntheir low-energy single particle spectrum can described by tilted massive Dirac\nHamiltonians. The so-called Janus materials fall into that category. Inversion\nsymmetry can also be broken by the application of out-of-plane electric fields,\nor by the mere presence of a substrate. Here we explore the properties of\nexcitons in TMDC monolayers lacking inversion symmetry. We find that exciton\nbinding energies can be larger than the electronic band gap, making such\nmaterials promising candidates to host the elusive exciton insulator phase. We\nalso investigate the excitonic contribution to their optical conductivity and\ndiscuss the associated optical selection rules.",
        "positive": "Telegraph noise and the Fabry-Perot quantum Hall interferometer: We consider signatures of abelian and nonabelian quasiparticle statistics in\nquantum Hall Fabry-Perot interferometers. When quasiparticles enter and exit\nthe interference cell, for instance due to glassy motion in the dopant layer,\nthe anyonic phase can be observed in phase jumps. In the case of the nonabelian\nnu=5/2 state, if the interferometer is small, we argue that free Majorana\nstates in the interference cell are either strongly coupled to one another or\nare strongly coupled to the edge. We analyze the expected phase jumps and in\nparticular suggest that changes in the parity of the Majorana ground state\nshould gives rise to characteristic jumps of pi in the interference phase."
    },
    {
        "anchor": "Observation of symmetry protected zero modes in topolectrical circuits: Higher-order topological insulators are a new class of topological phases of\nmatter, originally conceived for electrons in solids. It has been suggested\nthat $\\mathbb{Z}_N$ Berry phase (Berry phase quantized into $2\\pi/N$) is a\nuseful tool to characterize the symmetry protected topological states, while\nthe experimental evidence is still elusive. Recently, topolectrical circuits\nhave emerged as a simple yet very powerful platform for studying topological\nphysics that are challenging to realize in condensed matter systems. Here, we\npresent the first experimental observation of second-order corner states\ncharacterized by $\\mathbb{Z}_3$ Berry phase in topolectrical circuits. We\ndemonstrate theoretically and experimentally that the localized second-order\ntopological states are protected by a generalized chiral symmetry of tripartite\nlattices, and they are pinned to \"zero energy\". By introducing extra capacitors\nwithin sublattices in the circuit, we are able to examine the robustness of the\nzero modes against both chiral-symmetry conserving and breaking disturbances.\nOur work paves the way for testing exotic topological band theory by\nelectrical-circuit experiments.",
        "positive": "Landau-Zener Tunnelling in a Nonlinear Three-level System: We present a comprehensive analysis of the Landau-Zener tunnelling of a\nnonlinear three-level system in a linearly sweeping external field. We find the\npresence of nonzero tunnelling probability in the adiabatic limit (i.e., very\nslowly sweeping field) even for the situation that the nonlinear term is very\nsmall and the energy levels keep the same topological structure as that of\nlinear case. In particular, the tunnelling is irregular with showing an\nunresolved sensitivity on the sweeping rate. For the case of fast-sweeping\nfields, we derive an analytic expression for the tunnelling probability with\nstationary phase approximation and show that the nonlinearity can dramatically\ninfluence the tunnelling probability when the nonlinear \"internal field\"\nresonate with the external field. We also discuss the asymmetry of the\ntunnelling probability induced by the nonlinearity. Physics behind the above\nphenomena is revealed and possible application of our model to triple-well\ntrapped Bose-Einstein condensate is discussed."
    },
    {
        "anchor": "Impurity Effects in Two-Electron Coupled Quantum Dots: Entanglement\n  Modulation: We present a detailed analysis of the electronic and optical properties of\ntwo-electron quantum dots with a two-dimensional Gaussian confinement\npotential. We study the effects of Coulomb impurities and the possibility of\nmanipulate the entanglement of the electrons by controlling the confinement\npotential parameters. The degree of entanglement becomes highly modulated by\nboth the location and charge screening of the impurity atom, resulting two\nregimes: one of low entanglement and other of high entanglement, with both of\nthem mainly determined by the magnitude of the charge. It is shown that the\nmagnitude of the oscillator strength of the system could provide an indication\nof the presence and characteristics of impurities that could largely influence\nthe degree of entanglement of the system.",
        "positive": "Cold Fermionic Atoms in Two-Dimensional Traps -- Pairing versus Hund's\n  Rule: The microscopic properties of few interacting cold fermionic atoms confined\nin a two-dimensional (2D) harmonic trap are studied by numerical\ndiagonalization. For repulsive interactions, a strong shell structure\ndominates, with Hund's rule acting at its extreme for the mid-shell\nconfigurations. In the attractive case, odd-even oscillations due to pairing\noccur simultaneously with deformations in the internal structure of the ground\nstates, as seen from pair correlation functions."
    },
    {
        "anchor": "Electron-hole interactions in coupled InAs-GaSb quantum dots based on\n  nanowire crystal phase templates: We report growth and characterization of a coupled quantum dot structure that\nutilizes nanowire templates for selective epitaxy of radial heterostructures.\nThe starting point is a zinc blende InAs nanowire with thin segments of\nwurtzite structure. These segments have dual roles: they act as tunnel barriers\nfor electron transport in the InAs core, and they also locally suppress growth\nof a GaSb shell, resulting in coaxial InAs-GaSb quantum dots with integrated\nelectrical probes. The parallel quantum dot structure hosts spatially separated\nelectrons and holes that interact due to the type-II broken gap of InAs-GaSb\nheterojunctions. The Coulomb blockade in the electron and hole transport is\nstudied, and periodic interactions of electrons and holes are observed and can\nbe reproduced by modeling. Distorted Coulomb diamonds indicate voltage-induced\nground-state transitions, possibly a result of changes in the spatial\ndistribution of holes in the thin GaSb shell.",
        "positive": "Parafermion supporting platform based on spin transitions in the\n  fractional quantum Hall effect regime: We propose an experimentally-feasible system based on spin transitions in the\nfractional quantum Hall effect regime where parafermions, high-order\nnon-abelian excitations, can be potentially realized. We provide a\nproof-of-concept experiments showing that in specially designed\nheterostructures spin transitions at a filling factor 2/3 can be induced\nelectrostatically, allowing local control of polarization and on-demand\nformation of helical domain walls with fractionalized charge excitations, a\npre-requisite ingredient for parafermions formation. We also present exact\ndiagonalization numerical studies of domain walls formed between domains with\ndifferent spin polarization in the fractional quantum Hall effect regime and\nshow that they indeed possess electronic and magnetic structure needed for\nparafermion formation when coupled to an s-wave superconductor."
    },
    {
        "anchor": "Patterning graphene nanostripes in substrate-supported functionalized\n  graphene: A promising route to integrated, robust, and superior transistors: It is promising to apply quantum-mechanically confined graphene systems in\nfield-effect transistors. High stability, superior performance, and large-scale\nintegration are the main challenges facing the practical application of\ngraphene transistors. Our understandings of the adatom-graphene interaction\ncombined with recent progress in the nanofabrication technology indicate that\nvery stable and high-quality graphene nanostripes could be integrated in\nsubstrate-supported functionalized (hydrogenated or fluorinated) graphene using\nelectron-beam lithography. We also propose that parallelizing a couple of\ngraphene nanostripes in a transistor should be preferred for practical\napplication, which is also very useful for transistors based on graphene\nnanoribbon.",
        "positive": "Low-Energy Conductivity of Single- and Double-Layer Graphene from the\n  Uncertainty Principle: The minimum conductivity value as well as the linear dependence of\nconductivity on the charge density near the Dirac point in single and\ndoublelayer graphene is derived from the energy-time uncertainty principle\napplied to ballistic charge carriers."
    },
    {
        "anchor": "Monte-Carlo phase diagram of a Hubbard-Peierls model in the search for\n  spin crossover transition in $\u03c0$-conjugated polymers: We present a Monte Carlo study of the finite temperature properties of an\nextended Hubbard-Peierls model describing one dimensional $\\pi$-conjugated\npolymers. The model incorporates electron-phonon and hyperfine interaction and\nit is solved at the mean field level for half filling. In particular we explore\nthe model as a function of the strength of electron-electron and\nelectron-phonon interactions. At low temperature the system presents a\ndiamagnetic to antiferromagnetic transition as the electron-electron\ninteraction strength increases. At the same time by increasing the\nelectron-phonon coupling there is a transition from a homogeneous to a Peierls\ndimerized geometry. As expected such a Peierls dimerized phase disappears at\nfinite temperature as a result of thermal vibrations. More intriguing is the\ninterplay between the electron-phonon and the electron-electron interactions at\nfinite temperature. In particular we demonstrate that for a certain region of\nthe parameter space there is a spin-crossover, where the system transits from a\nlow-spin to a high-spin state as the temperature increases. In close analogy to\nstandard spin-crossover in divalent magnetic molecules such a transition is\nentropy driven. Finally we discuss the role played by the hyperfine interaction\nover the phase diagram.",
        "positive": "Multiple-path interferometer with a single quantum obstacle: We consider the scattering of particles by an obstacle which tunnels\ncoherently between two positions. We show that the obstacle mimics two\nclassical scatterers at fixed positions when the kinetic energy epsilon of the\nincident particles is smaller than the tunnel splitting Delta: If the obstacles\nare arranged in parallel, one observes an interference pattern as in the\nconventional double-slit experiment. If they are arranged in series, the\nobservations conform with a Fabry-Perot interferometer. At larger epsilon\ninelastic processes result in more complex interference phenomena. Interference\ndisappears when epsilon >> Delta, but can be recovered if only the elastic\nscattering channel is detected. We discuss the realization of a quantum\nobstacle in mesoscopic systems."
    },
    {
        "anchor": "Analysis of the conditional average and conditional variance of\n  dissipated energy in the driven spin-boson model: We investigate the conditional average and the conditional variance of\ndissipated energy considering, as a prototypical example, a driven spin-boson\nsystem. We follow a measurement protocol in which the spin is prepared in a\ncertain initial state before undergoing a periodic driving. Subsequently, the\nspin is projected onto a post-selected final state. We compare the conditional\naverage of dissipated energy to the lower bound which directly follows from the\nwell known fluctuation relations. We further report that a special selection of\nthe initial (pre-selected) and final (post-selected) spin states leads to an\nenhanced energy emission with simultaneous noise suppression at driving times\nof order of the relaxation time.",
        "positive": "Auto- and Cross-Correlation-Functions as entanglement quantifiers in\n  semiconductor microcavities: The dynamics of the exciton-photon entanglement, in a semiconductor\nmicrocavity is analyzed. Finding a closed analytical expression for the time\nevolution of the concurrence. Using as model two coupled, quantum oscillators\nwith detuning between them. Supposing that the system is at a temperature\ncloser to zero. And that the quantum state of the system, remains in the one\nexcitation sector of the total Hilbert space. The former theoretical setup,\ndescribes the excitons coupled to the photons in the microcavity accurately,\nfor a system with ultra low density of excitons. We remark in first place, that\nour closed expression for the concurrence dynamics. Enable us to establish a\ngood analytical criterion, to determine the coupling dynamical regime, in which\nthe system is. Even more, we show that our criterion, is in good agreement with\ntypically accepted, experimental signatures for strong, and wake coupling\nregimes. Finally we present theoretical evidence, suggesting that the\nentanglement between the exciton and the photon. Can be measured in\nexperiments, v\\'ia the cross correlation contribution, to the time resolved\nspectra of the system."
    },
    {
        "anchor": "Waveguide-integrated van der Waals heterostructure photodetector at\n  telecom band with high speed and high responsivity: Intensive efforts have been devoted to exploit novel optoelectronic devices\nbased on two-dimensional (2D) transition-metal dichalcogenides (TMDCs) owing to\ntheir strong light-matter interaction and distinctive material properties. In\nparticular, photodetectors featuring both high-speed and high-responsivity\nperformance are of great interest for a vast number of applications such as\nhigh-data-rate interconnects operated at standardized telecom wavelengths. Yet,\nthe intrinsically small carrier mobilities of TMDCs become a bottleneck for\nhigh-speed application use. Here, we present high-performance vertical van der\nWaals heterostructure-based photodetectors integrated on a silicon photonics\nplatform. Our vertical MoTe2/graphene heterostructure design minimizes the\ncarrier transit path length in TMDCs and enables a record-high measured\nbandwidth of at least 24GHz under a moderate bias voltage of -3 volts. Applying\na higher bias or employing thinner MoTe2 flakes boosts the bandwidth even to\n50GHz. Simultaneously, our device reaches a high external responsivity of\n0.2A/W for incident light at 1300nm, benefiting from the integrated waveguide\ndesign. Our studies shed light on performance trade-offs and present design\nguidelines for fast and efficient devices. The combination of 2D\nheterostructures and integrated guided-wave nano photonics defines an\nattractive platform to realize high-performance optoelectronic devices, such as\nphotodetectors, light-emitting devices and electro-optic modulators.",
        "positive": "Evolution of the surface states of the Luttinger semimetal under strain\n  and inversion-symmetry breaking: Dirac, line-node, and Weyl semimetals: The Luttinger model of a quadratic-node semimetal for electrons with the\n$j=\\frac32$ angular momentum under cubic symmetry is the parent,\nhighest-symmetry low-energy model for a variety of topological and strongly\ncorrelated materials, such as HgTe, $\\alpha$-Sn, and iridate compounds.\nPreviously, we have theoretically demonstrated that the Luttinger semimetal\nexhibits surface states. In the present work, we theoretically study the\nevolution of these surface states under symmetry-lowering perturbations:\ncompressive strain and bulk-inversion asymmetry (BIA). This system is quite\nspecial in that each consecutive perturbation creates a new type of a semimetal\nphase, resulting in a sequence of four semimetal phases, where each successive\nphase arises by modification of the nodal structure of the previous phase:\nunder compressive strain, the Luttinger semimetal turns into a Dirac semimetal,\nwhich under the linear-in-momentum BIA term turns into a line-node semimetal,\nwhich under the cubic-in-momentum BIA terms turns into a Weyl semimetal. We\ncalculate the surface states within the generalized Luttinger model for these\nfour semimetal phases within a ``semi-analytical'' approach and fully analyze\nthe corresponding evolution of the surface states. Importantly, for this\nsequence of four semimetal phases, there is a corresponding hierarchy of the\nlow-energy models describing the vicinities of the nodes. We derive most of\nthese models and demonstrate quantitative asymptotic agreement between the\nsurface-state spectra of some of them. This proves that the mechanisms\nresponsible for the surface states are fully contained in the low-energy models\nwithin their validity ranges, once they are supplemented with proper boundary\nconditions, and demonstrates that continuum models are perfectly applicable for\nstudying surface states."
    },
    {
        "anchor": "Electron temperature in electrically isolated Si double quantum dots: Charge-based quantum computation can be attained through reliable control of\nsingle electrons in lead-less quantum systems. Single-charge transitions in\nelectrically-isolated double quantum dots (DQD) realised in phosphorus-doped\nsilicon can be detected via capacitively coupled single-electron tunnelling\ndevices. By means of time-resolved measurements of the detector's conductance,\nwe investigate the dots' occupancy statistics in temperature. We observe a\nsignificant reduction of the effective electron temperature in the DQD as\ncompared to the temperature in the detector's leads. This sets promises to make\nisolated DQDs suitable platforms for long-coherence quantum computation.",
        "positive": "Theory of thermoelectric effect in insulators: We propose a thermopolarization effect with a purely electronic origin, where\nthe electric polarization $P$ is induced by the temperature gradient $\\nabla\nT$. This is observable as a Seebeck effect in a finite-size system where the\nlinear size $L$ is shorter than the Debye length $\\lambda$, which characterizes\nthe screening due to the thermal excitation of free carriers. The dual effect\nis the ac heat current induced by the time derivative of the electric field\n$E$. The Seebeck coefficient $S$ diverges as $\\sim t_{\\mathrm{asym}}/eT$ when\nthe temperature $T$ goes to $0$, where $t_{\\mathrm{asym}}$ represents the\nasymmetry of the conduction band and the valence band and $e$ is the elementary\ncharge."
    },
    {
        "anchor": "Coherent transport in Josephson-Junction rhombi chain with quenched\n  disorder: We consider a chain of Josephson-junction rhombi (proposed originally by\nDoucot and Vidal) in quantum regime. In a regular chain with no disorder in the\nmaximally frustrated case when magnetic flux through each rhombi \\Phi_r is\nequal to one half of superconductive flux quantum \\Phi_0, Josephson current is\ndue to correlated transport of pairs of Cooper pairs, i.e. charge is quantized\nin units of $4e$. Sufficiently strong deviation \\delta\\Phi =|\\Phi_r-\\Phi_0/2| >\n\\delta\\Phi^c from the maximally frustrated point brings the system back to\nusual $2e$-quantized supercurrent. For a regular chain \\delta\\Phi^c was\ncalculated by us previously. Here we present detailed analysis of the effect of\nquenched disorder (random stray charges and random fluxes piercing rhombi) on\nthe pairing effect.",
        "positive": "Non-classical light from superconducting resonators coupled to\n  voltage-biased Josephson junctions: The interplay of the tunneling transfer of charges and the emission and\nabsorption of light can be investigated in a set-up, where a voltage-biased\nJosephson junction is placed in series to a microwave cavity. Here, we\nconcentrate on the emission process and show that due to the inherent\nnonlinearity of the Josephson junction tunneling Cooper-pairs can create a\nvariety of non-classical states of light. Depending on experimental parameters\nand tuning the device can be described by effective Hamiltonians, indicating\nspecific photon creation mechanisms which lead to strongly bunched or\nanti-bunched light emission. We derive explicit analytical expressions for the\nphoton correlation function $g^{(2)}(\\tau=0)$ for these different processes and\ninvestigate their full crossover numerically. Photon distribution functions\nshow squeezing and other interesting non-Poissonian behavior."
    },
    {
        "anchor": "Coherent microwave generation by spintronic feedback oscillator: The transfer of spin angular momentum to a nanomagnet from a spin polarized\ncurrent provides an efficient means of controlling the magnetization direction\nin nanomagnets. A unique consequence of this spin torque is that the\nspontaneous oscillations of the magnetization can be induced by applying a\ncombination of a dc bias current and a magnetic field. Here we experimentally\ndemonstrate a different effect, which can drive a nanomagnet into spontaneous\noscillations without the need of external spin torque injection. For the\ndemonstration of this effect, we use a nano-pillar of magnetic tunnel junction\n(MTJ) powered by a dc current and connected to a coplanar waveguide (CPW) lying\nabove the free layer of the MTJ. Any fluctuation of the free layer\nmagnetization is converted into oscillating voltage via the tunneling\nmagneto-resistance effect and is fed back into the MTJ by the CPW through\ninductive coupling. As a result of this feedback, the magnetization of the free\nlayer can be driven into a continual precession. The combination of MTJ and CPW\nbehaves similar to a laser system and outputs a stable rf power with quality\nfactor exceeding 10,000.",
        "positive": "Nonlocal transport mediated by nonlocal Hikami boxes: Condensation of\n  evanescent quasiparticles injected into the superconducting gap: Evanescent quasiparticles entering a superconductor and propagating over\ndistances larger than the coherence length give rise to intermediate states\ninduced by double Andreev scattering on disorder.The resulting effective\nattractive interaction between evanescent quasiparticles is retarded at the\nextremely slow frequency of the applied bias voltage. The non-BCS\nout-of-equilibrium mesoscopic condensate is compatible with a recent experiment\n[S. Russo et al., Phys. Rev. Lett. 95, 027002 (2005)]. Microscopic theory is\ndiscussed in the random phase approximation."
    },
    {
        "anchor": "Non-Equilibrium Pathways for Excitation of Bulk and Surface Phonons\n  through Anharmonic Coupling: Upon impulsive optical excitation of solid-state materials, the\nnon-equilibrium flow of energy from the excited electronic system to the\nlattice degrees of freedom typically happens in a few picoseconds. Here we\nidentified the surface of thin Bi films grown on Si(001) as an additional\nsubsystem which is excited much slower on a 100 ps timescale that is caused by\ndecoupling due to mismatched phonon dispersions relations of bulk and surface.\nAnharmonic coupling among the phonon systems provides pathways for excitations\nwhich exhibits a 1/T-dependence causing a speed-up of surface excitation at\nhigher temperatures. A quantitative justification is provided by phonon Umklapp\nprocesses from lattice thermal conductivity of the Bi bulk. Three-temperature\nmodel simulations reveal a pronounced non-equilibrium situation up to\nnanoseconds: initially, the surface is colder than the bulk, that situation is\nthen inverted during cooling and the surface feeds energy back into the bulk\nphonon system.",
        "positive": "Multisubband transport and magnetic deflection of Fermi electron\n  trajectories in three terminal junctions and rings: We study the electron transport in three terminal junctions and quantum rings\nlooking for the classical deflection of electron trajectories in presence of\nintersubband scattering. We indicate that although the Aharonov-Bohm\noscillations and the Lorentz force effects co-exist in the low subband\ntransport, for higher Fermi energies a simultaneous observation of the both\neffects is difficult and calls for carefully formed structures. In particular,\nin quantum rings with channels wider than the input lead the Lorentz force is\nwell resolved but the Aharonov-Bohm periodicity is lost in chaotic scattering\nevents. In quantum rings with equal length of the channels and $T$-shaped\njunctions the Aharonov-Bohm oscillations are distinctly periodic but the\nLorentz force effects are not well pronounced. We find that systems with the\nwedge shaped junctions allow for observation of both the periodic Aharonov-Bohm\noscillations and the magnetic deflection."
    },
    {
        "anchor": "Non-abelian topology of nodal-line rings in\n  $\\mathcal{P}\\mathcal{T}$-symmetric systems: Nodal lines inside the momentum space of three-dimensional crystalline solids\nare topologically stabilized by a $\\pi$-flux of Berry phase. Nodal-line rings\nin $\\mathcal{PT}$-symmetric systems with negligible spin-orbit coupling (here\ndescribed as \"nodal class AI\") can carry an additional \"monopole charge\", which\nfurther enhances their stability. Here, we relate two recent theoretical\nadvancements in the study of band topology in nodal class AI. On the one hand,\ncohomology classes of real vector bundles were used to relate the monopole\ncharge of nodal-line rings to their linking with nodal lines formed among the\noccupied and among the unoccupied bands. On the other hand, homotopy studies\nrevealed that the generalization of the Berry-phase quantization to the case of\nmultiple band gaps defines a non-Abelian topological charge, which governs the\npossible deformations of the nodal lines. The present work has three aims.\nFirst, we present how to efficiently wield the recently discovered non-Abelian\ntopological charge. Second, we apply these methods to present an independent\nproof of the relation between the monopole charge and the linking structure,\nincluding all the fragile-topology exceptions. Finally, we show that the\nmonopole charge flips sign when braided along a path with a non-trivial Berry\nphase. This facilitates a new type non-Abelian \"braiding\" of nodal-line rings\ninside the momentum space, that has not been previously reported. The work\nbegins with a brief review of $\\mathcal{PT}$-symmetric band topology, and the\ngeometric arguments employed in our theoretical analysis are supplemented in\nthe appendices with formal mathematical derivations.",
        "positive": "Anyon Condensation and Continuous Topological Phase Transitions in\n  Non-Abelian Fractional Quantum Hall States: We find a series of possible continuous quantum phase transitions between\nfractional quantum Hall (FQH) states at the same filling fraction in\ntwo-component quantum Hall systems. These can be driven by tuning the\ninterlayer tunneling and/or interlayer repulsion. One side of the transition is\nthe Halperin (p,p,p-3) Abelian two-component state while the other side is the\nnon-Abelian Z4 parafermion (Read-Rezayi) state. We predict that the transition\nis a continuous transition in the 3D Ising class. The critical point is\ndescribed by a Z2 gauged Ginzburg-Landau theory. These results have\nimplications for experiments on two-component systems at \\nu = 2/3 and\nsingle-component systems at \\nu = 8/3."
    },
    {
        "anchor": "The spin-orbit interaction as a source of new spectral and transport\n  properties in quasi-one-dimensional systems: We present an exact theoretical study of the effect of the spin-orbit (SO)\ninteraction on the band structure and low temperature transport in long\nquasi-one-dimensional electron systems patterned in two-dimensional electron\ngases in zero and weak magnetic fields. We reveal the manifestations of the SO\ninteraction which cannot in principle be observed in higher dimensional\nsystems.",
        "positive": "Spin-mediated photomechanical coupling of a nanoelectromechanical\n  shuttle: We show that nano-mechanical vibrations in a magnetic shuttle device can be\nstrongly affected by external microwave irradiation through photo-assisted\nelectronic spin-flip transitions. Mechanical consequences of these spin-flips\nare due to a spin-dependent magnetic force, which may lead to a nano-mechanical\ninstability in the device. We derive a criterion for the instability to\nactually occur and analyze different regimes of possible nano-mechanical\noscillations. Possible experimental realizations of the spin-mediated\nphoto-mechanical instability and detection of the device back action are\ndiscussed."
    },
    {
        "anchor": "Current-controlled magnetization dynamics in the spin-flip transistor: The current driven magnetization dynamics of a thin-film, three magnetic\nterminal device (spin-flip transistor) is investigated theoretically. We\nconsider a magnetization configuration in which all magnetizations are in the\ndevice plane, with source-drain magnetizations chosen fixed and antiparallel,\nwhereas the third contact magnetization is allowed to move in a weak anisotropy\nfield that guarantees thermal stability of the equilibrium structure at room\ntemperature. We analyze the magnetization dynamics of the free layer under a dc\nsource-drain bias current within the macrospin model and magneto-electronic\ncircuit theory. A new tunable two-state behavior of the magnetization is found\nand the advantages of this phenomenon and potential applications are discussed.",
        "positive": "Magnetoresistivity Modulated Response in Bichromatic Microwave\n  Irradiated Two Dimensional Electron Systems: We analyze the effect of bichromatic microwave irradiation on the\nmagnetoresistivity of a two dimensional electron system. We follow the model of\nmicrowave driven Larmor orbits in a regime where two different microwave lights\nwith different frequencies are illuminating the sample ($w_{1}$ and $w_{2}$).\nOur calculated results demonstrate that now the electronic orbit centers are\ndriven by the superposition of two harmonic oscillatory movements with the\nfrequencies of the microwave sources. As a result the magnetoresisitivity\nresponse presents modulated pulses in the amplitude with a frequency of\n$\\frac{w_{1}-w_{2}}{2}$, whereas the main response oscillates with\n$\\frac{w_{1}+w_{2}}{2}$."
    },
    {
        "anchor": "Observation of oscillating $g$-factor anisotropy arising from strong\n  crystal lattice anisotropy in GaAs spin-3/2 hole quantum point contacts: Many modern spin-based devices rely on the spin-orbit interaction, which is\nhighly sensitive to the host semiconductor heterostructure and varies\nsubstantially depending on crystal direction, crystal asymmetry (Dresselhaus),\nand quantum confinement asymmetry (Rashba). One-dimensional quantum point\ncontacts are a powerful tool to probe both energy and directional dependence of\nspin-orbit interaction through the effect on the hole $g$-factor. In this work\nwe investigate the role of cubic crystal asymmetry in driving an oscillation in\nthe in-plane hole $g$-factor anisotropy when the quantum point contact is\nrotated with respect to the crystal axes, and we are able to separate\ncontributions to the Zeeman Hamiltonian arising from Rashba and cubic crystal\nasymmetry spin-orbit interactions. The in-plane $g$-factor is found to be\nextremely sensitive to the orientation of the quantum point contact, changing\nby a factor of $5$ when rotated by $45^{\\circ}$. This exceptionally strong\ncrystal lattice anisotropy of the in-plane Zeeman splitting cannot be explained\nwithin axially symmetric theoretical models. Theoretical modelling based on the\ncombined Luttinger, Rashba and Dresselhaus Hamiltonians that we use here\nreveals new spin-orbit contributions to the in-plane hole $g$-factor and\nprovides an excellent agreement with our experimental data.",
        "positive": "Quantum Point Contacts: 1. Quantized conductance\n  2. When 1 mode = 1 atom\n  3. Photons and Cooper pairs\n  4. Thermal analogues\n  5. Shot noise\n  6. Solid-state electron optics\n  7. Ultimate confinement\n  8. Landauer formulas"
    },
    {
        "anchor": "Optical spin transfer and spin-orbit torques in thin film ferromagnets: We study the optically induced torques in thin film ferromagnetic layers\nunder excitation by circularly polarized light. We study cases both with and\nwithout Rashba spin-orbit coupling using a 4-band model. In the absence of\nRashba spin-orbit coupling, we derive an analytic expression for the optical\ntorques, revealing the conditions under which the torque is mostly derived from\noptical spin transfer torque (i.e. when the torque is along the direction of\noptical angular momentum), versus when the torque is derived from the inverse\nFaraday effect (i.e. when the torque is perpendicular to the optical angular\nmomentum). We find the optical spin transfer torque dominates provided that the\nexcitation energy is far away from band edge transitions, and the magnetic\nexchange splitting is much greater than the lifetime broadening. For the case\nwith large Rashba spin-orbit coupling and out-of-plane magnetization, we find\nthe torque is generally perpendicular to the photon angular momentum and is\nascribed to an optical Edelstein effect.",
        "positive": "Quantum anomalous Hall effects controlled by chiral domain walls: We report the interplay between two different topological phases in condensed\nmatter physics, the magnetic chiral domain wall (DW), and the quantum anomalous\nHall (QAH) effect. We show that the chiral DW driven by Dzyaloshinskii-Moriya\ninteraction (DMI) can divide the uniform domain into several zones where the\nneighboring zone possesses opposite quantized Hall conductance. The separated\ndomain with a chiral edge state (CES) can be continuously modified by external\nmagnetic field-induced domain expansion and thermal fluctuation, which gives\nrise to the reconfigurable QAH effect. More interestingly, we show that the\nposition of CES can be tuned by spin current-driven chiral DW motion. Several\ntwo-dimensional magnets with high Curie temperatures and large topological band\ngaps are proposed for realizing these phenomena. Our work thus reveals the\npossibility of chiral DW controllable QAH effects."
    },
    {
        "anchor": "Topological defects in helical magnets: Helical magnets which violated space inversion symmetry have rather peculiar\ntopological defects. In isotropic helical magnets with exchange and\nDzyaloshinskii-Moriya interactions there are only three types of linear\ndefects: $\\pm\\pi$ and $2\\pi$-disclinations. Weak crystal anysotropy suppresses\nlinear defects on large scale. Instead planar defects appear: domain walls that\nseparate domains with different preferential directions of helical wave\nvectors. The appearance of such domain walls in the bulk helical magnets and\nsome of their properties were predicted in the work \\cite{Li 2012}. In a recent\nwork by an international team of experimenters and theorists \\cite{Schoenherr\n2018} the existence of new types of domain walls on crystal faces of helical\nmagnet FeGe was discovered. They have many features predicted by theory\n\\cite{Li 2012}, but display also unexpected properties, one of them is the\npossibility of arbitrary angle between helical wave vectors. Depending on this\nangle the domain walls observed in \\cite{Schoenherr 2018} can be divided in two\nclasses: smooth and zig-zag. This article contains a mini-review of the\nexisting theory and experiment. It also contains new results that explain why\nin a system with continuos orientation of helical wave vectors domain walls are\npossible. We discuss why and at what conditions smooth and zig-zag domain walls\nappear, analyze spin textures associated with helical domain walls and find the\ndependence of their width on angle between helical wave vectors.",
        "positive": "Strong Effects of Interlayer Interaction on Valence-Band Splitting in\n  Transition Metal Dichalcogenides: Understanding the origin of valence band maxima (VBM) splitting in transition\nmetal dichalcogenides (TMDs) is important because it governs the unique spin\nand valley physics in monolayer and multilayer TMDs. In this work, we present\nour systematic study of VBM splitting ($\\Delta$) in atomically thin MoS$_2$ and\nWS$_2$ by employing photocurrent spectroscopy as we change the temperature and\nthe layer numbers. We found that VBM splitting in monolayer MoS$_2$ and WS$_2$\ndepends strongly on temperature, which contradicts the theory that spin-orbit\ncoupling solely determines the VBM splitting in monolayer TMDs. We also found\nthat the rate of change of VBM splitting with respect to temperature\n($m=\\frac{\\partial\\Delta}{\\partial T}$) is the highest for monolayer (-0.14\nmeV/K for MoS$_2$) and the rate decreases as the layer number increases ($m ~\n0$ meV/K for 5 layers MoS$_2$). We performed density functional theory (DFT)\nand the GW with Bethe-Salpeter Equation (GW-BSE) calculations to determine the\nelectronic band structure and optical absorption for a bilayer MoS$_2$ with\ndifferent interlayer separations. Our simulations agree with the experimental\nobservations and demonstrate that the temperature dependence of VBM splitting\nin atomically thin monolayer and multilayer TMDs originates from the changes in\nthe interlayer coupling strength between the neighboring layers. By studying\ntwo different types of TMDs and many different layer thicknesses, we also\ndemonstrate that VBM splitting also depends on the layer numbers and type of\ntransition metals. Our study will help understand the role spin-orbit coupling\nand interlayer interaction play in determining the VBM splitting in quantum\nmaterials and develop next-generation devices based on spin-orbit interactions."
    },
    {
        "anchor": "Bennett clocking of nanomagnetic logic using electrically induced\n  rotation of magnetization in multiferroic single-domain nanomagnets: The authors show that it is possible to rotate the magnetization of a\nmultiferroic (strain-coupled two-layer magnetostrictive-piezoelectric)\nnanomagnet by a large angle with a small electrostatic potential. This can\nimplement Bennett clocking in nanomagnetic logic arrays resulting in\nunidirectional propagation of logic bits from one stage to another. This method\nof Bennett clocking is superior to using spin-transfer torque or local magnetic\nfields for magnetization rotation. For realistic parameters, it is shown that a\npotential of ~ 0.2 V applied to a multiferroic nanomagnet can rotate its\nmagnetization by nearly 900 to implement Bennett clocking.",
        "positive": "Distinguishing Spin Relaxation Mechanisms in Organic Semiconductors: A theory is introduced for spin relaxation and spin diffusion of hopping\ncarriers in a disordered system. For disorder described by a distribution of\nwaiting times between hops (e.g. from multiple traps, site-energy disorder\nand/or positional disorder) the dominant spin relaxation mechanisms in organic\nsemiconductors (hyperfine, hopping-induced spin-orbit, and intra-site spin\nrelaxation) each produce different characteristic spin relaxation and spin\ndiffusion dependences on temperature. The resulting unique experimental\nsignatures predicted by the theory for each mechanism in organic semiconductors\nprovide a prescription for determining the dominant spin relaxation mechanism."
    },
    {
        "anchor": "Revisiting the physical origin and nature of surface states in\n  inverted-band semiconductors: We revisit the problem of surface states in semiconductors with inverted band\nstructures, such as $\\alpha$-Sn and HgTe. We unravel the confusion that arose\nover the past decade regarding the origin of the surface states, their\ntopological nature, and the role of strain. Within a single minimalistic\ndescription, we reconcile different solutions found in the 1980s with the\nresults obtained from modern-day numerical simulations, allowing us to\nunambiguously identify all branches of surface states around the $\\Gamma$-point\nof the Brillouin zone in different regimes. We also show that strain is a\nsmooth \"deformation\" to the surface states, following the usual continuity\nprinciple of physics, and not leading to any drastic change of the physical\nproperties in these materials, in contrast to what has recently been advanced\nin the literature. We consider biaxial in-plane strain that is either tensile\nor compressive, leading to different branches of surface states for topological\ninsulators and Dirac semimetals, respectively. Our model can help in\ninterpreting numerous experiments on topological surface states originating\nfrom inverted-band semiconductors.",
        "positive": "Magic-angle twisted bilayer graphene under orthogonal and in-plane\n  magnetic fields: We investigate the effect of a magnetic field on the band structure of a\nbilayer graphene with a magic twist angle of 1.08{\\deg}. The coupling of\ntight-binding model and Peierls phase allows the calculation of the energy\nbands of periodic two-dimensional systems. For an orthogonal magnetic field,\nthe Landau levels turn out to be dispersive, especially for magnetic lengths\ncomparable or larger than the twisted bilayer cell size. A high in-plane\nmagnetic field modifies the low-energy bands and gap, which we demonstrate to\nbe a direct consequence of the minimal coupling."
    },
    {
        "anchor": "Reconciling edge states with compressible stripes in a ballistic\n  mesoscopic conductor: The well-known Landauer-Buttiker (LB) picture used to explain the quantum\nHall effect uses the concept of (chiral) edge states that carry the current. In\ntheir seminal 1992 article, Chklovskii, Shklovskii and Glazman (CSG) showed\nthat the LB picture does not account for some very basic properties of the gas,\nsuch as its density profile, as it lacks a proper treatment of the\nelectrostatic energy. They showed that, instead, one should consider alternated\nstripes of compressible and incompressible phases. In this letter, we revisit\nthis issue using a full solution of the quantum-electrostatic problem of a\nnarrow ballistic conductor, beyond the CSG approach. We recover the LB channels\nat low field and the CSG compressible/incompressible stripes at high field. Our\ncalculations reveal the existence of a third \"hybrid\" phase at intermediate\nfield. This hybrid phase has well defined LB type edge states, yet possesses a\nLandau level pinned at the Fermi energy as in the CSG picture. We calculate the\nmagneto-conductance which reveals the interplay between the LB and CSG regimes.\nOur results have important implications for the propagation of edge\nmagneto-plasmons.",
        "positive": "Nontrivial relaxation dynamics of excitons in high-quality InGaAs/GaAs\n  quantum wells: Photoluminescence (PL) and reflectivity spectra of a high-quality InGaAs/GaAs\nquantum well structure reveal a series of ultra-narrow peaks attributed to the\nquantum confined exciton states. The intensity of these peaks decreases as a\nfunction of temperature, while the linewidths demonstrate a complex and\npeculiar behavior. At low pumping the widths of all peaks remain quite narrow\n($< 0.1$ meV) in the whole temperature range studied, $4 - 30K$. At the\nstronger pumping, the linewidth first increases and than drops down with the\ntemperature rise. Pump-probe experiments show two characteristic time scales in\nthe exciton decay, $< 10$ps and $15 - 45ns$, respectively. We interpret all\nthese data by an interplay between the exciton recombination within the light\ncone, the exciton relaxation from a non-radiative reservoir to the light cone,\nand the thermal dissociation of the non-radiative excitons. The broadening of\nthe low energy exciton lines is governed by the radiative recombination and\nscattering with reservoir excitons while for the higher energy states the\nlinewidths are also dependent on the acoustic phonon relaxation processes."
    },
    {
        "anchor": "Atomistic Mechanisms of Codoping-Induced p- to n-Type Conversion in\n  Nitrogen-Doped Graphene: It was recently shown that nitrogen-doped graphene (NG) can exhibit both p-\nand n-type characters depending on the C-N bonding nature, which represents a\nsignificant bottleneck for the development of graphene-based electronics. Based\non first-principles calculations, we herein scrutinise the correlations between\natomic and electronic structures of NG, and particularly explore the\nfeasibility of converting p-type NG with pyridinic, pyrrolic, and nitrilic N\ninto n- or bipolar type by introducing an additional dopant atom. Out of the\nnine candidates, B, C, O, F, Al, Si, P, S, and Cl, we find that the B-, Al-,\nand P-codoping can anneal even relatively large vacancy defects in p-type NG.\nIt will be also shown that, while the NG with pyridinic N can be converted into\nn-type via codoping, only the bipolar type conversion can be achieved for the\nNG with nitrilic or pyrrolic N. The amount of work function reduction was up to\n0.64 eV for the pyridinic N next to a monovacancy. The atomistic origin of such\ndiverse type changes is analysed based on Mulliken and crystal orbital\nHamiltonian populations, which provide us with a framework to connect the local\nbonding chemistry with macroscopic electronic structure in doped and/or\ndefective graphene. Moreover, we demonstrate that the proposed codoping scheme\ncan recover the excellent charge transport properties of pristine graphene.\nBoth the type conversion and conductance recovery in codoped NG should have\nsignificant implications for the electronic and energy device applications.",
        "positive": "Weak Localization in Electric-Double-Layer Gated Few-layer Graphene: We induce surface carrier densities up to $\\sim7\\cdot 10^{14}$cm$^{-2}$ in\nfew-layer graphene devices by electric double layer gating with a polymeric\nelectrolyte. In 3-, 4- and 5-layer graphene below 20-30K we observe a\nlogarithmic upturn of resistance that we attribute to weak localization in the\ndiffusive regime. By studying this effect as a function of carrier density and\nwith ab-initio calculations we derive the dependence of transport, intervalley\nand phase coherence scattering lifetimes on total carrier density. We find that\nelectron-electron scattering in the Nyquist regime is the main source of\ndephasing at temperatures lower than 30K in the $\\sim10^{13}$cm$^{-2}$ to\n$\\sim7 \\cdot 10^{14}$cm$^{-2}$ range of carrier densities. With the increase of\ngate voltage, transport elastic scattering is dominated by the competing\neffects due to the increase in both carrier density and charged scattering\ncenters at the surface. We also tune our devices into a crossover regime\nbetween weak and strong localization, indicating that simultaneous tunability\nof both carrier and defect density at the surface of electric double layer\ngated materials is possible."
    },
    {
        "anchor": "Which phase is measured in the mesoscopic Aharonov-Bohm interferometer?: Mesoscopic solid state Aharonov-Bohm interferometers have been used to\nmeasure the \"intrinsic\" phase, $\\alpha_{QD}$, of the resonant quantum\ntransmission amplitude through a quantum dot (QD). For a two-terminal \"closed\"\ninterferometer, which conserves the electron current, Onsager's relations\nrequire that the measured phase shift $\\beta$ only \"jumps\" between 0 and $\\pi$.\nAdditional terminals open the interferometer but then $\\beta$ depends on the\ndetails of the opening. Using a theoretical model, we present quantitative\ncriteria (which can be tested experimentally) for $\\beta$ to be equal to the\ndesired $\\alpha_{QD}$: the \"lossy\" channels near the QD should have both a\nsmall transmission and a small reflection.",
        "positive": "Non-local transport signatures of topological superconductivity in a\n  phase-biased planar Josephson junction: Hybrid Josephson junctions realized on a two-dimensional electron gas are\nconsidered promising candidates for developing topological elements that are\neasily controllable and scalable. Here, we theoretically study the possibility\nof the detection of topological superconductivity via the non-local\nspectroscopy technique. We show that the non-local conductance is related to\nthe system band structure, allowing probe of the gap closing and reopening\nrelated to the topological transition. We demonstrate that the topological\ntransition induces a change in the sign of the non-local conductance at zero\nenergy due to the change in the quasiparticle character of the dispersion at\nzero momentum. Importantly, we find that the tunability of the superconducting\nphase difference via flux in hybrid Josephson junctions systems is strongly\ninfluenced by the strength of the Zeeman interaction, which leads to\nconsiderable modifications in the complete phase diagram that can be measured\nunder realistic experimental conditions."
    },
    {
        "anchor": "Magneto-optical conductivity in the type-I and type-II phases of\n  Weyl/multi-Weyl semimetals: Magneto-optical conductivity is a very widely studied transport coefficient,\nuseful to understand and characterize the behaviour of materials under magnetic\nfields. Using the Kubo formula, we compute the components of the conductivity\ntensor $\\sigma_{\\mu \\nu}$ transverse to a uniform magnetic field $\\mathbf B$,\nfor a single node of a multi-Weyl semimetal (with monopole charge $J$ equal to\ntwo or three). We also include the results for a Weyl semimetal (with $J=1$),\nand identify peaks in the conductivity profile which were not reported in\nearlier studies. In our analysis, we explore how the tilting of the\nWeyl/multi-Weyl cone affects $\\sigma_{\\mu \\nu}$, focussing on both type-I and\ntype-II phases. All these systems have a linear-in-momentum dispersion along\nthe tilting axis, which is chosen to align with $\\mathbf B$. In the type-II\nphases, open Fermi pockets appear as artifacts of the low-energy effective\ncontinuum models, which ignore higher-order momentum terms of the actual\nbandstructures. Hence, we supplement the linear power term with a cubic term,\nwhich closes the Fermi pockets, thus eliminating any need for an ad hoc cutoff\nfor the momentum integrals. Our results reveal that the absorptive parts of\n$\\sigma_{\\mu \\nu}$ display multiple peaks as functions of the frequency, whose\nlocations are determined by an energy scale $\\sim |\\mathbf B|^{J/2} $.",
        "positive": "Acoustoelectric Effect in degenerate Carbon Nanotube: Acoustoelectric Effect $AE$ in degenerate Carbon Nanotube ($CNT$) was\ntheoretically studied for hypersound in the regime $ql >> 1$. The dependence of\nacoustoelectric current $j^{ac}$ on the acoustic wave number $\\vec{q}$ and\nfrequency $\\omega_q$ at $T = 10K$ and scattering angle ($\\theta > 0$) was\nevaluated at various harmonics $n =\\pm 1, 2, ...$ (where $n$ is an integer). In\nthe first harmonics ($n = \\pm 1$), the non-linear dependence of $j^{ac}$ on\n$\\omega_q$ and $\\vec{q}$ were obtained. For $n = \\pm 2$, the numerically\nevaluated $j^{ac}$ qualitatively agreed with an experimentally obtained result."
    },
    {
        "anchor": "Fermi-arcs mediated transport in surface Josephson junctions of Weyl\n  semimetal: This study presents Fermi-arcs mediated transport in a Weyl semimetal thin\nslab, interfacing two $s$-wave superconductors. We present detailed study with\nboth time-reversal and inversion symmetry broken Weyl semimetals under\ngrounding, orbital magnetic fields, and Zeeman fields. An orbital magnetic\nfield induces energy level oscillations, while a Zeeman field give rise to the\nperiodic anomalous oscillations in the Josephson current. These anomalous\noscillations correlate with the separation of Weyl nodes in momentum space,\njunction length, and system symmetries. Additionally, we present an explanation\nby scattering theory modeling the Fermi-arcs as a network model.",
        "positive": "Spatially resolved manipulation of single electrons in quantum dots\n  using a scanned probe: The scanning metallic tip of a scanning force microscope was coupled\ncapacitively to electrons confined in a lithographically defined gate-tunable\nquantum dot at a temperature of 300 mK. Single electrons were made to hop on or\noff the dot by moving the tip or by changing the tip bias voltage owing to the\nCoulomb-blockade effect. Spatial images of conductance resonances map the\ninteraction potential between the tip and individual electronic quantum dot\nstates. Under certain conditions this interaction is found to contain a\ntip-voltage induced and a tip-voltage independent contribution."
    },
    {
        "anchor": "All-electrical Magnon Transport Experiments in Magnetically Ordered\n  Insulators: Angular momentum transport is one of the cornerstones of spintronics. Spin\nangular momentum is not only transported by mobile charge carriers, but also by\nthe quantized excitations of the magnetic lattice in magnetically ordered\nsystems. In this regard, magnetically ordered insulators provide a platform for\nmagnon spin transport experiments without additional contributions from spin\ncurrents carried by mobile electrons. In combination with charge-to-spin\ncurrent conversion processes in conductors with finite spin-orbit coupling it\nis possible to realize all-electrical magnon transport schemes in thin film\nheterostructures. This review provides an insight into such experiments and\nrecent breakthroughs achieved. Special attention is given to charge current\nbased manipulation via an adjacent normal metal of magnon transport in\nmagnetically ordered insulators in terms of spin-transfer torque. Moreover, the\ninfluence of two magnon modes with opposite spin in antiferromagnetic\ninsulators on all-electrical magnon transport experiments is discussed.",
        "positive": "Investigation of the surface properties of different highly aligned\n  N-MWCNT carpets: We investigated the physicochemical surface properties of different highly\naligned nitrogen-doped multi-walled carbon nanotube (N-MWCNT) carpets,\nsynthesized using toluene/pyrazine, toluene/benzylamine and acetonitrile via a\nsublimation-based chemical vapor deposition (SCVD) method at 760{\\deg}C. The\nsurfaces of the N-MWCNT carpets synthesized using toluene/pyrazine and\ntoluene/benzylamine were very hydrophobic. In contrast, we observed a complete\nwetting of the N-MWCNT carpets synthesized using acetonitrile. The difference\nin the wetting behavior of these N-MWCNT carpets is the main focus in this\nstudy and was not investigated before. Here, we show that not only the presence\nor concentration of nitrogen inside the carbon lattice, but especially it's\nkind of incorporation have an important influence on the surface polarity."
    },
    {
        "anchor": "Two-dimensional superconductivity of the Ca-intercalated graphene on\n  SiC: vital role of the interface between monolayer graphene and the substrate: Ca-intercalation has opened a way for superconductivity in graphene on SiC.\nHowever, the atomic and electronic structures being critical for\nsuperconductivity are still under discussion. We find the essential role of the\ninterface between monolayer graphene and the SiC substrate for\nsuperconductivity. In the Ca-intercalation process, at the interface a carbon\nlayer terminating SiC changes to graphene by Ca-termination of SiC (monolayer\ngraphene becomes bilayer) with inducing more carriers than a free-standing\nmodel. Then, Ca is intercalated in-between graphene layers, which shows\nsuperconductivity with the updated critical temperature ($T_{C}$) of up to 5.7\nK. In addition, the relation between $T_{C}$ and the normal-state conductivity\nis unusual, \"dome-shape\". These findings are beyond the simple C6CaC6 model in\nwhich s-wave BCS superconductivity is theoretically predicted. This work\nproposes a general picture of the intercalation-induced superconductivity in\ngraphene on SiC, and shed the light on the potential of superconductivity\ninduced by other intercalants.",
        "positive": "Gate-controlled generation of optical pulse trains using individual\n  carbon nanotubes: We report on optical pulse-train generation from individual air-suspended\ncarbon nanotubes under an application of square-wave gate voltages.\nElectrostatically-induced carrier accummulation quenches photoluminescence,\nwhile a voltage sign reversal purges those carriers, resetting the nanotubes to\nbecome luminescent temporarily. Frequency domain measurements reveal\nphotoluminescence recovery with characteristic frequencies that increase with\nexcitation laser power, showing that photoexcited carriers quench the emission\nin a self-limiting manner. Time-resolved measurements directly confirm the\npresence of an optical pulse train sychronized to the gate voltage signal, and\nflexible control over pulse timing and duration is demonstrated."
    },
    {
        "anchor": "Scattering theory of topological insulators and superconductors: The topological invariant of a topological insulator (or superconductor) is\ngiven by the number of symmetry-protected edge states present at the Fermi\nlevel. Despite this fact, established expressions for the topological invariant\nrequire knowledge of all states below the Fermi energy. Here, we propose a way\nto calculate the topological invariant employing solely its scattering matrix\nat the Fermi level without knowledge of the full spectrum. Since the approach\nbased on scattering matrices requires much less information than the\nHamiltonian-based approaches (surface versus bulk), it is numerically more\nefficient. In particular, is better-suited for studying disordered systems.\nMoreover, it directly connects the topological invariant to transport\nproperties potentially providing a new way to probe topological phases.",
        "positive": "Spin Photovoltaic Effect in Magnetic van der Waals Heterostructures: The development of van der Waals (vdW) crystals and their heterostructures\nhas created a fascinating platform for exploring optoelectronic properties in\nthe two-dimensional (2D) limit. With the recent discovery of 2D magnets, the\ncontrol of the spin degree of freedom can be integrated to realize 2D\nspin-optoelectronics with spontaneous time-reversal symmetry breaking. Here, we\nreport spin photovoltaic effects in vdW heterostructures of atomically thin\nmagnet chromium triiodide (CrI3) sandwiched by graphene contacts. In the\nabsence of a magnetic field, the photocurrent displays a distinct dependence on\nlight helicity, which can be tuned by varying the magnetic states and photon\nenergy. Circular polarization-resolved absorption measurements reveal that\nthese observations originate from magnetic-order-coupled and thus\nhelicity-dependent charge-transfer exciton states. The photocurrent displays\nmultiple plateaus as the magnetic field is swept, which are associated with\ndifferent spin configurations enabled by the layered antiferromagnetism and\nspin-flip transitions in CrI3. Remarkably, giant photo-magnetocurrent is\nobserved, which tends to infinity for a small applied bias. Our results pave\nthe way to explore emergent photo-spintronics by engineering magnetic vdW\nheterostructures."
    },
    {
        "anchor": "Networks of silicon nanowires: a large-scale atomistic electronic\n  structure analysis: Networks of silicon nanowires possess intriguing electronic properties\nsurpassing the predictions based on quantum confinement of individual\nnanowires. Employing large-scale atomistic pseudopotential computations, as yet\nunexplored branched nanostructures are investigated in the subsystem level, as\nwell as in full assembly. The end product is a simple but versatile expression\nfor the bandgap and band edge alignments of multiply-crossing Si nanowires for\nvarious diameters, number of crossings, and wire orientations. Further progress\nalong this line can potentially topple the bottom-up approach for Si nanowire\nnetworks to a top-down design by starting with functionality and leading to an\nenabling structure.",
        "positive": "Frequency stabilization and noise-induced spectral narrowing in\n  resonators with zero dispersion: Mechanical resonators are widely used as precision clocks and sensitive\ndetectors that rely on the stability of their eigenfrequencies. The phase noise\nis determined by different factors ranging from thermal noise and frequency\nnoise of the resonator to noise in the feedback circuitry. Increasing the\nvibration amplitude can mitigate some of these effects but the improvements are\nlimited by nonlinearities that are particularly strong for miniaturized micro-\nand nano-mechanical systems. Here we design a micromechanical resonator with\nnon-monotonic dependence of the frequency of eigenoscillations on energy. Near\nthe extremum, where the dispersion of the eigenfrequency is zero, the system\nregains certain characteristics of a linear resonator, albeit at large\nvibration amplitudes. The spectral peak undergoes counter-intuitive narrowing\nwhen the noise intensity is increased. With the resonator serving as the\nfrequency determining element in a feedback loop, the phase noise at the\nextremum amplitude is three times smaller than the conventional nonlinear\nregime. Zero dispersion phenomena open new opportunities for improving resonant\nsensors and frequency references."
    },
    {
        "anchor": "Spontaneous Skyrmion Conformal Lattice and Transverse Motion During dc\n  and ac Compression: We use atomistic-based simulations to investigate the behavior of\nferromagnetic skyrmions being continuously compressed against a rigid wall\nunder dc and ac drives. The compressed skyrmions can be annihilated close to\nthe wall and form a conformal crystal with both a size and a density gradient,\nmaking it distinct from conformal crystals observed previously for\nsuperconducting vortices and colloidal particles. For both dc and ac driving,\nthe skyrmions can move transverse to the compression direction due to a\ncombination of density and size gradients. Forces in the compression direction\nare converted by the Magnus force into transverse motion. Under ac driving, the\namount of skyrmion annihilation is reduced and we find a skyrmion Magnus\nratchet pump. We also observe shear banding in which skyrmions near the wall\nmove up to twice as fast as skyrmions further from the wall. When we vary the\nmagnitude of the applied drive, we find a critical current above which the\nskyrmions are completely annihilated during a time scale that depends on the\nmagnitude of the drive. By varying the magnetic parameters, we find that the\ntransverse motion is strongly dependent on the skyrmion size. Smaller skyrmions\nare more rigid, which interferes with the size gradient and destroys the\ntransverse motion. We also confirm the role of the size gradient by comparing\nour atomistic simulations with a particle-based model, where we find that the\ntransverse motion is only transient. Our results are relevant for applications\nwhere skyrmions encounter repulsive magnetic walls, domain walls, or\ninterfaces.",
        "positive": "Spin freezing by Anderson localization in one-dimensional semiconductors: One-dimensional quantum wires are considered as prospective elements for spin\ntransport and manipulation in spintronics. We study spin dynamics in\nsemiconductor GaAs-like nanowires with disorder and spin-orbit interaction by\nusing a rotation in the spin subspace gauging away the spin-orbit field. If the\ndisorder is sufficiently strong, the spin density after a relatively short\nrelaxation time reaches a plateau. This effect is a manifestation of the\nAnderson localization and depends in a universal way on the disorder and the\nspin-orbit coupling strength. As a result, at a given disorder, semiconductor\nnanowires can permit a long-term spin polarization tunable with the spin-orbit\ninteractions."
    },
    {
        "anchor": "Microwave Admittance of Gold-Palladium Nanowires with Proximity-Induced\n  Superconductivity: We report quantitative electrical admittance measurements of diffusive\nsuperconductor--normal-metal--superconductor (SNS) junctions at gigahertz\nfrequencies and millikelvin temperatures. The gold-palladium-based SNS\njunctions are arranged into a chain of superconducting quantum interference\ndevices. The chain is coupled strongly to a multimode microwave resonator with\na mode spacing of approximately 0.6 GHz. By measuring the resonance frequencies\nand quality factors of the resonator modes, we extract the dissipative and\nreactive parts of the admittance of the chain. We compare the phase and\ntemperature dependence of the admittance near 1 GHz to theory based on the\ntime-dependent Usadel equations. This comparison allows us to identify\nimportant discrepancies between theory and experiment that are not resolved by\nincluding inelastic scattering or elastic spin-flip scattering in the theory.",
        "positive": "Energetics and Structure of Domain Wall Networks in Minimally Twisted\n  Bilayer Graphene under Strain: The parameters of the triangular domain wall network in bilayer graphene with\na simultaneously twisted and biaxially stretched bottom layer are studied using\nthe two-chain Frenkel-Kontorova model. It is demonstrated that if the graphene\nlayers are free to rotate, they prefer to stay co-aligned upon stretching the\nbottom layer and the regular triangular network of tensile domain walls is\nformed upon the commensurate-incommensurate phase transition. If the angle\nbetween the layers is fixed, the regular triangular network of shear domain\nwalls is observed at zero elongation of the bottom layer. Upon stretching the\nbottom layer, however, the domain walls transform into the tensile ones and the\nsize of the commensurate domains decreases. We also show that the parameters of\nthe isosceles triangular domain wall network in twisted bilayer graphene under\nshear strain can be determined through purely geometrical considerations.\nExperimental analysis of the orientation of domain walls and period of the\ntriangular network would, on the one hand, contribute to understanding of the\ninterlayer interaction of graphene layers, and, on the other hand, serve for\ndetection of relative strains and rotation between the layers. Vice versa\nexternal strains can be used to control the parameters of the triangular domain\nwall network and, therefore, electronic properties of twisted bilayer graphene."
    },
    {
        "anchor": "Principles and simulations of high-resolution STM imaging with flexible\n  tip apex: We present a robust but still efficient simulation approach for\nhigh-resolution scanning tunneling microscopy with a flexible tip apex showing\nsharp submolecular features. The approach takes into account the electronic\nstructure of sample and tip and relaxation of the tip apex. We validate our\nmodel by achieving good agreement with various experimental images which allows\nus to explain the origin of several observed features. Namely, we have found\nthat high-resolution STM mechanism consists of the standard STM imaging,\nconvolving electronic states of the sample and the tip apex orbital structure,\nwith the contrast heavily distorted by the relaxation of the flexible apex\ncaused by interaction with the substrate.",
        "positive": "Singlet and triplet Cooper pair splitting in hybrid superconducting\n  nanowires: In most naturally occurring superconductors, electrons with opposite spins\nare paired up to form Cooper pairs. This includes both conventional $s$-wave\nsuperconductors such as aluminum as well as high-$T_\\text{c}$, $d$-wave\nsuperconductors. Materials with intrinsic $p$-wave superconductivity, hosting\nCooper pairs made of equal-spin electrons, have not been conclusively\nidentified, nor synthesized, despite promising progress. Instead, engineered\nplatforms where $s$-wave superconductors are brought into contact with magnetic\nmaterials have shown convincing signatures of equal-spin pairing. Here, we\ndirectly measure equal-spin pairing between spin-polarized quantum dots. This\npairing is proximity-induced from an $s$-wave superconductor into a\nsemiconducting nanowire with strong spin-orbit interaction. We demonstrate such\npairing by showing that breaking a Cooper pair can result in two electrons with\nequal spin polarization. Our results demonstrate controllable detection of\nsinglet and triplet pairing between the quantum dots. Achieving such triplet\npairing in a sequence of quantum dots will be required for realizing an\nartificial Kitaev chain."
    },
    {
        "anchor": "Quantum spin Hall effect from multi-scale band inversion in twisted\n  bilayer Bi$_2$(Te$_{1-x}$Se$_x$)$_3$: Moir\\'e materials have become one of the most active fields in material\nscience in recent years due to their high tunability, and their unique\nproperties emerge from the Moir\\'e-scale structure modulation. Here, we propose\ntwisted bilayer Bi$_2$(Te$_{1-x}$Se$_x$)$_3$ as a new Moir\\'e material where\nthe Moir\\'e-scale modulation induces a topological phase transition. We show,\nin twisted bilayer Bi$_2$(Te$_{1-x}$Se$_x$)$_3$, a topological insulator domain\nand a normal insulator domain coexist in the Moir\\'e lattice structure, and\nedge states on the domain boundary make nearly flat bands that dominate the\nmaterial properties. The edge states further contribute to a Moir\\'e-scale band\ninversion, resulting in Moir\\'e-scale topological states. There are\ncorresponding Moir\\'e-scale edge states and they are so to speak \"edge state\nfrom edge state\", which is a unique feature of twisted bilayer\nBi$_2$(Te$_{1-x}$Se$_x$)$_3$. Our result not only proposes novel quantum phases\nin twisted bilayer Bi$_2$Te$_3$-family, but also suggests the twisting of\nstacking sensitive topological materials paves an avenue in the search for\nnovel quantum materials and devices.",
        "positive": "Field-induced breakdown of the quantum Hall effect: A numerical analysis is made of the breakdown of the quantum Hall effect\ncaused by the Hall electric field in competition with disorder. It turns out\nthat in the regime of dense impurities, in particular, the number of localized\nstates decreases exponentially with the Hall field, with its dependence on the\nmagnetic and electric field summarized in a simple scaling law. The physical\npicture underlying the scaling law is clarified. This intra-subband process,\nthe competition of the Hall field with disorder, leads to critical breakdown\nfields of magnitude of a few hundred V/cm, consistent with observations, and\naccounts for their magnetic-field dependence \\propto B^{3/2} observed\nexperimentally. Some testable consequences of the scaling law are discussed."
    },
    {
        "anchor": "Deterministic transfer of optical-quality carbon nanotubes for\n  atomically defined technology: When continued device scaling reaches the ultimate limit imposed by atoms,\ntechnology based on atomically precise structures is expected to emerge. Device\nfabrication will then require building blocks with identified atomic\narrangements and assembly of the components without contamination. Here we\nreport on a versatile dry transfer technique for deterministic placement of\noptical-quality carbon nanotubes. Single-crystalline anthracene is used as a\nmedium which readily sublimes by mild heating, leaving behind clean nanotubes\nand thus enabling bright photoluminescence. We are able to position nanotubes\nof a desired chirality with a sub-micron accuracy under in-situ optical\nmonitoring, thereby demonstrating deterministic coupling of a nanotube to a\nphotonic crystal nanobeam cavity. A cross junction structure is also designed\nand constructed by repeating the nanotube transfer, where intertube exciton\ntransfer is observed. Our results represent an important step towards\ndevelopment of devices consisting of atomically precise components and\ninterfaces.",
        "positive": "A Hartree-Fock study of the $\u03bd=0$ quantum Hall state of monolayer\n  graphene with short range interactions: Recent experiments involving tilted graphene samples have shown evidence of a\ncontinuous phase transition in the $\\nu=0$ quantum Hall bulk state. We present\nhere a simple model that supports such a transition. In addition to a long\nrange SU(4) symmetric Coulomb interaction, we include Hubbard on-site and\nnearest neighbor interactions with tunable coupling strengths, and perform a\nself-consistent Hartree-Fock analysis. A large sea of negative energy Landau\nlevels is retained, and is shown to have important qualitative and quantitative\neffects. Phase diagrams are constructed within the space of physically relevant\nparameters, yielding results consistent with experimental observation."
    },
    {
        "anchor": "Ballistic surface channels in fully in situ defined Bi$_4$Te$_3$\n  Josephson junctions with aluminum contacts: In this letter we report on the electrical transport properties of\nBi$_4$Te$_3$ in a Josephson junction geometry using superconducting Al\nelectrodes with a Ti interdiffusion barrier. Bi$_4$Te$_3$ is proposed to be a\ndual topological insulator, for which due to time-reversal and mirror symmetry\nboth a strong topological insulator phase as well as a crystalline topological\nphase co-exist. The formation of a supercurrent through the Bi$_4$Te$_3$ layer\nis explained by a two-step process. First, due to the close proximity of the\nAl/Ti electrodes a superconducting gap is induced within the Bi$_4$Te$_3$ layer\nright below the electrodes. The size of this gap is determined by analysing\nmultiple Andreev reflections (MARs) identified within the devices differential\nresistance at low voltage biases. Second, based on the Andreev reflection and\nreverse Andreev reflection processes a supercurrent establishes in the weak\nlink region in between these two proximity coupled regions. Analyses of the\ntemperature dependency of both the critical current as well as MARs indicate\nmostly ballistic supercurrent contributions in between the proximitized\nBi$_4$Te$_3$ regions even though the material is characterized by a\nsemi-metallic bulk phase. The presence of these ballistic modes gives\nindications on the topological nature of Bi$_4$Te$_3$.",
        "positive": "Superconductivity at metal-antiferromagnetic insulator interfaces: Magnons in antiferromagnetic insulators couple strongly to conduction\nelectrons in adjacent metals. We show that this interfacial tie can lead to\nsuperconductivity in a tri-layer consisting of a metal sandwiched between two\nantiferromagnetic insulators. The critical temperature is closely related to\nthe magnon gap, which can be in the THz range. We estimate the critical\ntemperature in MnF$_2$-Au-MnF$_2$ to be on the order of 1 K. The Umklapp\nscattering at metal-antiferromagnet interfaces leads to a d-wave\nsuperconductive pairing, in contrast to the p-wave superconductivity mediated\nby magnons in ferromagnets."
    },
    {
        "anchor": "Gate-controlled current switch in graphene: We study numerically cross conductances in a four-terminal all-graphene\nsetup. We show that far away from the Dirac point current flows along zigzag\ndirections, giving the possibility to guide the current between terminals using\na tunable pn-junction. The device operates as a gate-controlled current switch,\nand the electronic properties of graphene are crucial for efficient\nperformance.",
        "positive": "Diffusive magnetotransport in a two-dimensional Rashba system: An analytical approach to calculation of the conductivity tensor, $\\sigma$,\nof a two-dimensional (2D) electron system with Rashba spin-orbit interaction\n(SOI) in an orthogonal magnetic field is proposed. The electron momentum\nrelaxation is assumed to be due to electron scattering by a random field of\nshort-range impurities, which is taken into account in the Born approximation.\nAn exact expression for the one-particle Green function of an electron with\nRashba SOI in an arbitrary magnetic field is suggested. This expression allows\nus to obtain analytical formulas for the density of states (DOS) and $\\sigma$\nin the self-consistent Born and ladder approximation, respectively, which hold\ntrue in a wide range of magnetic fields, from the weak ($\\omega_{c}\\tau << 1$)\nup to the quantizing ($\\omega_{c}\\tau\\gtrsim 1$) ones. It is shown that in the\nladder approximation the Rashba SOI has no effect at all on the conductivity\nmagnitude in the whole range of classical (non quantizing) magnetic fields. The\nShubnikov-de Haas (SdH) oscillation period is shown to be related to the total\ncharge carrier concentration by the conventional formula, irrespective of the\nSOI magnitude. A simple equation defining the location of the SdH oscillation\nbeating nodes is obtained. The results are in good agreement with the\nexperimental and recent numerical investigations."
    },
    {
        "anchor": "Topological defects in the edge state structure in a bilayer electron\n  system: We experimentally demonstrate, for the first time, formation of point-like\ntopological defects in the edge state structure in the quantum Hall effect\nregime. By using of a selective population technique, we investigate\nequilibration processes between the edge states in bilayer electron structures\nwith a high tunnelling rate between layers. Unexpected flattening of the I-V\ncurves in perpendicular magnetic field at a specific filling factor combination\nand the recovery of the conventional nonlinear I-V characteristics in tilted\nfields give a strong evidence for the existence of topological defects.",
        "positive": "Density-functional calculations of multivalency-driven formation of\n  Te-based monolayer materials with superior electronic and optical properties: Contemporary science is witnessing a rapid expansion of the two-dimensional\n(2D) materials family, each member possessing intriguing emergent properties of\nfundamental and practical importance. Using the particle-swarm optimization\nmethod in combination with first-principles density functional theory\ncalculations, here wepredict a new category of 2D monolayers named tellurene,\ncomposed of the metalloid element Te, with stable 1T-MoS2-like ( {\\alpha}-Te),\nand metastable tetragonal (\\b{eta}-Te) and 2H-MoS2-like ({\\gamma}-Te)\nstructures. The underlying formation mechanism of such tri-layer arrangements\nis uniquely rooted in the multivalent nature of Te, with the central-layer Te\nbehaving more metal-like (e.g., Mo), and the two outer layers more\nsemiconductor-like (e.g.,S). In particular, the {\\alpha}-Te phase can be\nspontaneously obtained from the magic thicknesses truncated along the [001]\ndirection of the trigonal structure of bulk Te. Furthermore, both the {\\alpha}-\nand \\b{eta}-Te phases possess electron and hole mobilities much higher than\nMoS2, as well as salient optical absorption properties. These findings\neffectively extend the realm of 2D materials to group-VI monolayers, and\nprovide a new and generic formation mechanism for designing 2D materials."
    },
    {
        "anchor": "Self-organized pseudo-graphene on grain boundaries in topological band\n  insulators: Semi-metals are characterized by nodal band structures that give rise to\nexotic electronic properties. The stability of Dirac semi-metals, such as\ngraphene in two spatial dimensions (2D), requires the presence of lattice\nsymmetries, while akin to the surface states of topological band insulators,\nWeyl semi-metals in three spatial dimensions (3D) are protected by band\ntopology. Here we show that in the bulk of topological band insulators,\nself-organized topologically protected semi-metals can emerge along a grain\nboundary, a ubiquitous extended lattice defect in any crystalline material. In\naddition to experimentally accessible electronic transport measurements, these\nstates exhibit valley anomaly in 2D influencing edge spin transport, whereas in\n3D they appear as graphene-like states that may exhibit an odd-integer quantum\nHall effect. The general mechanism underlying these novel semi-metals -- the\nhybridization of spinon modes bound to the grain boundary -- suggests that\ntopological semi-metals can emerge in any topological material where lattice\ndislocations bind localized topological modes.",
        "positive": "Theory of scanning gate microscopy imaging of the supercurrent\n  distribution in a planar Josephson junction: We theoretically investigate the mapping of the supercurrent distribution in\na planar superconductor-normal-superconductor junction in the presence of a\nperpendicular magnetic field via the scanning gate microscopy technique. We\nfind that the distribution of counter-propagating supercurrents aligned in\nJosephson vortices can be mapped by the change of the critical current induced\nby the tip of the scanning probe, if the flux in the junction is set close to\nmaxima of the Fraunhofer pattern. Instead, when the magnetic field drives the\njunction to a supercurrent minimum in the Fraunhofer pattern, the\nsuperconducting phase adapts, and the tip always increases the supercurrent.\nThe perpendicular magnetic field leads to the formation of Josephson vortices,\nwhose extension for highly transparent junctions depends on the current\ncirculation direction. We show that this leads to an asymmetric supercurrent\ndistribution in the junction and that this can be revealed by scanning gate\nmicroscopy. We explain our findings on the basis of numerical calculations for\nboth short- and long-junction limits and provide a phenomenological model for\nthe observed phenomena."
    },
    {
        "anchor": "Gap prediction in hybrid graphene - hexagonal boron nitride nanoflakes\n  using artificial neural networks: The electronic properties graphene nanoflakes (GNFs) with embedded hexagonal\nboron nitride (hBN) domains are investigated by combined {\\it ab initio}\ndensity functional theory calculations and machine learning techniques. The\nenergy gaps of the quasi-0D graphene based systems, defined as the differences\nbetween LUMO and HOMO energies, depend on the sizes of the hBN domains relative\nto the size of the pristine graphene nanoflake, but also on the position of the\nhBN domain. The range of the energy gaps for different configurations is\nincreasing as the hBN domains get larger. We develop two artificial neural\nnetwork (ANN) models able to reproduce the gap energies with high accuracies\nand investigate the tunability of the energy gap, by considering a set of GNFs\nwith embedded rectangular hBN domains. In one ANN model, the input is in\none-to-one correspondence with the atoms in the GNF, while in the second model\nthe inputs account for basic structures in the GNF, allowing potential use in\nup-scaled structures. We perform a statistical analysis over different\nconfigurations of ANNs to optimize the network structure. The trained ANNs\nprovide a correlation between the atomic system configuration and the magnitude\nof the energy gaps, which may be regarded as an efficient tool for optimizing\nthe design of nanostructured graphene based materials for specific electronic\nproperties.",
        "positive": "Transport Properties of Near Surface InAs Two-dimensional\n  Heterostructures: Two-dimensional electron systems (2DESs) confined to the surface of\nnarrowband semiconductors have attracted great interest since they can easily\nintegrate with superconductivity (or ferromagnetism) enabling new possibilities\nin hybrid device architectures and study of exotic states in proximity of\nsuperconductors. In this work, we study indium arsenide heterostructures where\ncombination of clean interface with superconductivity, high mobility and\nspin-orbit coupling can be achieved. The weak antilocalization measurements\nindicate presence of strong spin-orbit coupling at high densities. We study the\nmagnetotransport as a function of top barrier and density and report clear\nobservation of integer quantum Hall states. We report improved electron\nmobility reaching up to 44,000 cm$^{2}$/Vs in undoped heterstructures and well\ndeveloped integer quantum Hall states starting as low as 2.5~T."
    },
    {
        "anchor": "Density Matrix Renormalization Group Study of Incompressible Fractional\n  Quantum Hall States: We develop the Density Matrix Renormalization Group (DMRG) technique for\nnumerically studying incompressible fractional quantum Hall (FQH) states on the\nsphere. We calculate accurate estimates for ground state energies and\nexcitationgaps at FQH filling fractions \\nu=1/3 and \\nu=5/2 for systems that\nare almost twice as large as the largest ever studied by exact diagonalization.\nWe establish, by carefully comparing with existing numerical results on smaller\nsystems, that DMRG is a highly effective numerical tool for studying\nincompressible FQH states.",
        "positive": "Inverse Spin Hall Effect in NiFe / Normal Metal Bilayers: Spin pumping in ferromagnets provides a source of pure spin currents. Via the\ninverse spin Hall effect a spin current is converted into a charge current and\na corresponding detectable DC-voltage. The ratio of injected spin current to\nresulting charge current is given by the spin Hall angle. However, the number\nof experiments more or less equals the number of different values for spin Hall\nangles, even for the most studied normal metal platinum. This publication\nprovides a full study of inverse spin Hall effect and anisotropic\nmagnetoresistance for different NiFe(Py) / normal metal bilayers using a\ncoplanar waveguide structure. Angle and frequency dependent measurements\nstrongly suggest that spin pumping and inverse spin Hall effect can be used to\nquantify spin Hall angles only if certain conditions are met. Ruling out the\nanisotropic magnetoresistance as a parasitic voltage generating effect\nmeasurements of the inverse spin Hall effect in Py/Pt and Py/Au yield spin Hall\nangles of 0.09 and 0.008 respectively. Furthermore, DC-voltages at\nferromagnetic resonance for Py/Pt are studied as a function of temperature and\nthe results are compared to theoretical models."
    },
    {
        "anchor": "Subnanosecond single electron source in the time-domain: We describe here the realization of a single electron source similar to\nsingle photon sources in optics. On-demand single electron injection is\nobtained using a quantum dot connected to the conductor via a tunnel barrier of\nvariable transmission (quantum point contact). Electron emission is triggered\nby a sudden change of the dot potential which brings a single energy level\nabove the Fermi energy in the conductor. A single charge is emitted on an\naverage time ranging from 100 ps to 10 ns ultimately determined by the barrier\ntransparency and the dot charging energy. The average single electron emission\nprocess is recorded with a 0.5 ns time resolution using a real-time fast\nacquisition card. Single electron signals are compared tosimulation based on\nscattering theory approach adapted for finite excitation energies.",
        "positive": "Noise-assisted Thouless pump in elastically deformable molecular\n  junctions: We study a Thouless pump realized with an elastically \\textit{deformable\nquantum dot} whose center of mass follows a non-linear stochastic dynamics. The\ninterplay of noise, non-linear effects, dissipation and interaction with an\nexternal time-dependent driving on the pumped charge is fully analyzed. The\nresults show that the quantum pumping mechanism not only is not destroyed by\nthe force fluctuations, but it becomes stronger when the forcing signal\nfrequency is tuned close to the resonance of the vibrational mode. The\nrobustness of the quantum pump with temperature is also investigated and an\nexponential decay of the pumped charge is found when the coupling to the\nvibrational mode is present. Implications of our results for\nnano-electromechanical systems are also discussed."
    },
    {
        "anchor": "Large excitonic binding energy in GaN based superluminescent light\n  emitting diode on naturally survived sub-10 nm lateral nanowires: We demonstrate a novel method for nanowire formation by natural selection\nduring wet chemical etching in boiling Phosphoric acid. It is observed that\nwire lateral dimensions of sub-10 nm and lengths of 700 nm or more have been\nnaturally formed during the wet etching. The dimension variation is controlled\nthrough etching times wherein the underlying cause is the merging of the nearby\ncrystallographic hexagonal etch pits. The emission processes involving excitons\nare found to be efficient and lead to enhanced emission characteristics. The\nexciton binding energy is augmented by using quantum confinement whereby\nenforcing greater overlap of the electron-hole wave-function. The surviving\nnanowires are nearly defect-free, have large exciton binding energies of around\n45 meV and a small temperature variation of the output electroluminescent\nlight. We have observed superluminescent behaviour of the LEDs formed on these\nnanowires. There is no observable efficiency roll off till current densities of\n400 A/cm2. The present work thus provides an innovative and cost effective\nmanner of device fabrication on the formed nanowires and proves the immediate\nperformance enhancement achievable.",
        "positive": "Tunable double-Weyl Fermion semimetal state in the SrSi$_2$ materials\n  class: We discuss first-principles topological electronic structure of\nnoncentrosymmetric SrSi$_2$ materials class based on the hybrid\nexchange-correlation functional. Topological phase diagram of SrSi$_2$ is\nmapped out as a function of the lattice constant with focus on the semimetal\norder. A tunable double-Weyl Fermion state in Sr$_{1-x}$Ca$_{x}$Si$_2$ and\nSr$_{1-x}$Ba$_{x}$Si$_2$ alloys is identified. Ca doping in SrSi$_2$ is shown\nto yield a double-Weyl semimetal with a large Fermi arc length, while Ba doping\nleads to a transition from the topological semimetal to a gapped insulator\nstate. Our study indicates that SrSi$_2$ materials family could provide an\ninteresting platform for accessing the unique topological properties of Weyl\nsemimetals."
    },
    {
        "anchor": "Topological insulators based on HgTe: The most interesting experimental results obtained in studies of 2D and 3D\ntopological insulators (TIs) based on HgTe quantum wells and films are\nreviewed. In the case of 2D TIs, these include the observation of nonlocal\nballistic and diffusion transport, the magnetic breakdown of 2D TIs, and an\nanomalous temperature dependence of edge-channel resistance. In 3D TIs, a\nrecord-setting high mobility of surface two-dimensional Dirac fermions (DFs)\nhas been attained. This enabled determining all the main TI parameters (the\nbulk gap and the density of DFs on both of its surfaces) and provided\ninformation on the phase of the Shubnikov - de Haas oscillations of DFs, which\nindicates the rigid topological coupling between the fermion spin and momentum.\nProspects for further research are discussed in the conclusion.",
        "positive": "Coherence in magnetic quantum tunneling: Currently, spin tunneling at very low temperatures is assumed to proceed as\nan incoherent sequence of events that take place whenever a bias field h(t)\nthat varies randomly with time t becomes sufficiently small, as in Landau-Zener\ntransitions. We study the behavior of a suitably defined coherence time t_p.\nCoherence effects become significant when t_p >= t_h$, where t_h is the\ncorrelation time for h(t). The theory of tunneling of Prokof'ev and Stamp (PS),\nwhich rests on the assumption that t_p <= t_h, is extended beyond this\nconstraint. It is shown, both analytically and numerically, that t_p >= t_h\nwhen t_h*dh <= h, where dh is the rms deviation of h. Equations that give t_p\nand the tunneling rate as a function of t_h*dh both for t_h*dh>=h, where the\ntheory of PS hold, and for t_h*dh <= h, where it does not, are derived."
    },
    {
        "anchor": "Anisotropic magneto-capacitance in ferromagnetic-plate capacitors: The capacitance of a parallel plate capacitor can depend on applied magnetic\nfield. Previous studies have identified capacitance changes induced via\nclassical Lorentz force or spin-dependent Zeeman effects. Here we measure a\nmagnetization direction dependent capacitance in parallel-plate capacitors\nwhere one plate is a ferromagnetic semiconductor, gallium manganese arsenide.\nThis anisotropic magneto-capacitance is due to the anisotropy in the density of\nstates dependent on the magnetization through the strong spin-orbit\ninteraction.",
        "positive": "Quantum fluctuations stabilize Skyrmion textures: Here we show that the zero point energy associated to the quantum spin\nfluctuations of a non- collinear spin texture produce Casimir-like magnetic\nfields. We study the effect of these Casimir fields on the topologically\nprotected non-collinear spin textures known as skyrmions. We calculate the zero\npoint energy, to the lowest order in the spin wave expansion, in a Heisenberg\nmodel with Dzyalonshinkii-Moriya interactions chosen so that the classical\nground state displays skyrmion textures, that disappear upon application of a\nstrong enough magnetic field. Our calculations show that the Casimir magnetic\nfield contributes a 10 percent of the total Zeeman energy necessary to delete\nthe skyrmion texture with an applied field, and is thereby an observable\neffect."
    },
    {
        "anchor": "Carrier thermal escape in families of InAs/InP self-assembled quantum\n  dots: We investigate the thermal quenching of the multimodal photoluminescence from\nInAs/InP (001) self-assembled quantum dots. The temperature evolution of the\nphotoluminescence spectra of two samples is followed from 10 K to 300 K. We\ndevelop a coupled rate-equation model that includes the effect of carrier\nthermal escape from a quantum dot to the wetting layer and to the InP matrix,\nfollowed by transport, recapture or non-radiative recombination. Our model\nreproduces the temperature dependence of the emission of each family of quantum\ndots with a single set of parameters. We find that the main escape mechanism of\nthe carriers confined in the quantum dots is through thermal emission to the\nwetting layer. The activation energy for this process is found to be close to\none-half the energy difference between that of a given family of quantum dots\nand that of the wetting layer as measured by photoluminescence excitation\nexperiments. This indicates that electron and holes exit the InAs quantum dots\nas correlated pairs.",
        "positive": "Entanglement Entropy of Non-Hermitian Free Fermions: We study the entanglement properties of non-Hermitian free fermionic models\nwith translation symmetry using the correlation matrix technique. Our results\nshow that the entanglement entropy has a logarithmic correction to the area law\nin both one-dimensional and two-dimensional systems. For any one-dimensional\none-band system, we prove that each Fermi point of the system contributes\nexactly 1/2 to the coefficient c of the logarithmic correction. Moreover, this\nrelation between c and Fermi point is verified for more general one-dimensional\nand two-dimensional cases by numerical calculations and finite-size scaling\nanalysis. In addition, we also study the single-particle and density-density\ncorrelation functions."
    },
    {
        "anchor": "Quantifying efficiency of remote excitation for surface enhanced Raman\n  spectroscopy in molecular junctions: Surface-enhanced Raman spectroscopy (SERS) is enabled by local surface\nplasmon resonances (LSPRs) in metallic nanogaps. When SERS is excited by direct\nillumination of the nanogap, the background heating of lattice and electrons\ncan prevent further manipulation of the molecules. To overcome this issue, we\nreport SERS in electromigrated gold molecular junctions excited remotely:\nsurface plasmon polaritons (SPPs) are excited at nearby gratings, propagate to\nthe junction, and couple to the local nanogap plasmon modes. Like direct\nexcitation, remote excitation of the nanogap can generate both SERS emission\nand an open-circuit photovoltage (OCPV). We compare SERS intensity and OCPV in\nboth direct and remote illumination configurations. SERS spectra obtained by\nremote excitation are much more stable than those obtained through direct\nexcitation when photon count rates are comparable. By statistical analysis of\n33 devices, coupling efficiency of remote excitation is calculated to be around\n10%, consistent with the simulated energy flow.",
        "positive": "Transport in partially equilibrated inhomogeneous quantum wires: We study transport properties of weakly interacting one-dimensional electron\nsystems including on an equal footing thermal equilibration due to\nthree-particle collisions and the effects of large-scale inhomogeneities. We\nshow that equilibration in an inhomogeneous quantum wire is characterized by\nthe competition of interaction processes which reduce the electrons total\nmomentum and such which change the number of right- and left-moving electrons.\nWe find that the combined effect of interactions and inhomogeneities can\ndramatically increase the resistance of the wire. In addition, we find that the\ninteractions strongly affect the thermoelectric properties of inhomogeneous\nwires and calculate their thermal conductance, thermopower, and Peltier\ncoefficient."
    },
    {
        "anchor": "Competition between horizontal and vertical polariton lasing in planar\n  microcavities: Planar microcavities filled with active materials containing excitonic\nresonances host radiative exciton-polariton (polariton) modes with in-plane\nwave vectors within the light cone. They also host at least one mode guided in\nthe cavity plane by total internal reflection and which is not radiatively\ncoupled to the vacuum modes except through defects or sample edges. We show\nthat polariton lasing mediated by polariton stimulated scattering can occur\nconcomitantly in both types of modes in a microcavity. By adjusting the\ndetuning between the exciton and the radiative photon mode one can favor\npolariton lasing either in the radiative or in the guided modes. Our results\nsuggest that the competition between these two types of polariton lasing modes\nmay have played a role in many previous observations of polariton lasing and\npolariton Bose Einstein condensation.",
        "positive": "Effect of boron nitride defects and charge inhomogeneity on 1/f noise in\n  encapsulated graphene: Low frequency 1/f noise is investigated in graphene, encapsulated between\nhexagonal boron nitride (hBN) substrate in dual gated geometry. The overall\nnoise magnitude is smaller as compared to graphene on Si/SiO2 substrate. The\nnoise amplitude in the hole doped region is independent of carrier density\nwhile in the electron doped region, a pronounced peak is observed, at Fermi\nenergy, EF ~ 90 meV. The physical mechanism of the anomalous noise peak in the\nelectron doped region is attributed to the impurity states originating from the\nCarbon atom replacing the Nitrogen site in hBN crystal. Furthermore, the noise\nstudy near Dirac point shows characteristic \"M-shape\", which is found to be\nstrongly correlated with the charge inhomogeneity region near Dirac point."
    },
    {
        "anchor": "Crystalline-electromagnetic responses of higher order topological\n  semimetals: Previous work has shown that time-reversal symmetric Weyl semimetals with a\nquadrupolar arrangement of first-order Weyl nodes exhibit a mixed\ncrystalline-electromagnetic response. For systems with higher order Weyl nodes,\nwhich are attached to both surface and hinge Fermi arcs, additional phenomena\nappear on surfaces of codimension $n>1$, such as electromagnetic responses of\nthe hinges. Here we construct a model possessing a quadrupole of higher order\nWeyl nodes to study the interplay between higher order topology and mixed\ncrystalline-electromagnetic responses. We show that the higher order nature of\nthe Weyl nodes yields a dipole of Dirac nodes on certain surfaces, leading to a\nmixed crystalline-electromagnetic \\emph{surface} response that binds charge to\ndislocations and momentum-density to magnetic fields. In addition, we show that\nthe model possesses a bulk quadrupole moment of crystal-momentum that provides\na link between the bulk and surface responses of the system.",
        "positive": "Orbital and spin magnetization of a confined electronic system in the\n  transition between a quantum dot and a ring: In order to understand the orbital and spin magnetization of a confined\nelectronic system we analyze these ground state properties in the transition\nfrom a quantum dot to a quantum ring of finite thickness. The Coulomb\ninteraction between the electrons is treated in the Hartree and Hartree-Fock\napproximations and special care is taken to include also the contributions of\nthe nonlocal current to the summation of the magnetic moments of the occupied\nstates. We identify changes in the many-body structure of the ground state and\nin the magnetization curves versus the magnetic field and other parameters\ncharacterizing the system. We compare the results of two models for quantum\ndots (or rings), one with the electrons moving continuously in the system, and\none with the electrons moving on a lattice."
    },
    {
        "anchor": "Why do Collapsed Carbon Nanotubes Twist?: We study the collapsing and subsequent spontaneous twisting of a carbon\nnanotube by in-situ transmission electron microscopy. A custom-sized nanotube\nis first created in the microscope by selectively extracting shells from a\nparent multi-wall tube. The few-wall, large-diameter daughter nanotube is\ndriven to collapse via mechanical stimulation, after which the ribbon-like\ncollapsed tube spontaneously twists along its long axis. In-situ diffraction\nexperiments fully characterize the uncollapsed and collapsed tubes. From the\nexperimental observations and associated theoretical analysis, the origin of\nthe twisting is determined to be compressive strain due to charge imbalance.",
        "positive": "Realization of Universal Quantum Gates with Spin-Qudits in Colloidal\n  Quantum Dots: We exploit hyperfine interactions in a single Mn-ion confined in a quantum\ndot (QD) to create a qudit, i.e. a multi-level quantum-bit system, with well\ndefined, addressable and robust set of spin states for the realization of\nuniversal quantum gates. We generate and probe an arbitrary superposition of\nstates between selected hyperfine energy level pairs by using electron double\nresonance detected nuclear magnetic resonance (EDNMR). This enables the\nobservation of Rabi oscillations and the experimental realization of NOT and\nSWAP universal quantum gates that are robust against decoherence. Our protocol\nfor cyclical preparation, manipulation and read-out of logic gates offers\nopportunities for integration of qudits in scalable quantum circuit\narchitectures beyond solid state electron spin qubits."
    },
    {
        "anchor": "Hysteresis loops of the magnetoconductance in graphene devices: We report very low temperature magnetoconductance DeltaG measurements on\ngraphene devices with the magnetic field H applied parallel to the carbon\nsheet. The DeltaG(H) signal depends on the gate voltage Vg and its sign is\nrelated with the universal conductance fluctuations. When the magnetic field is\nswept at fast rates, DeltaG displays hysteresis loops evident for different\nsizes and at different transport regimes of the devices. We attribute this to\nthe magnetization reversal of paramagnetic centres in graphene layer, which\nmight originate from defects in our devices.",
        "positive": "Ionized Impurity and Surface Roughness Scattering Rates of Electrons in\n  Semiconductor Structures with One-Dimensional Electron Gas and Broadened\n  Energy Levels: An approach to calculation of the ionized impurity and surface roughness\nscattering rates of electrons in very thin semiconductor quantum wires taking\ninto account the energy level broadening is worked out. It is assumed that all\nthe electrons in the structure are in the electric quantum limit. The screening\nis taken into account while considering the ionized impurity scattering.\nComparison of the surface roughness scat-tering rates calculated using the\nexponential and Gaussian autocorrelation functions is done."
    },
    {
        "anchor": "Photonic Devices Based On Black-Phosphorus and Combined Hybrid 2D\n  nanomaterials: Artificial semiconductor heterostructures played a pivotal role in modern\nelectronic and photonic technologies, providing a highly effective mean for the\nmanipulation and control of carriers, from the visible to the far-infrared.\nDespite the exceptional versatility, they commonly require challenging\nepitaxial growth procedures due to the need of clean and abrupt interfaces,\nwhich proved to be a major obstacle for the realization of room-temperature\n(RT), high-efficiency devices, like source, detectors or modulators. The\ndiscovery of graphene and the related fascinating capabilities have triggered\nan unprecedented interest in devices based on inorganic two-dimensional (2D)\nmaterials. Amongst them black-phosphorus (BP) recently showed an extraordinary\npotential in a variety of applications across micro-electronics and photonics.\nWith an energy gap in-between the gapless graphene and the larger gap\ntransition metal dichalcogenides, BP can form the basis for a new generation of\nhigh-performance photonic devices that could be engineered from \"scratch\" like\ntransparent saturable absorbers, fast photocounductive switch and low noise\nphotodetectors, exploiting its peculiar electrical, thermal and optical\nanisotropy. This paper will review the latest achievements in black\nphosphorus-based THz photonics and discuss future perspectives of this rapidly\ndeveloping research field.",
        "positive": "Probing two topological surface bands of Sb2Te3 by spin-polarized\n  photoemission spectroscopy: Using high resolution spin- and angle-resolved photoemission spectroscopy, we\nmap the electronic structure and spin texture of the surface states of the\ntopological insulator Sb2Te3. In combination with density functional\ncalculations (DFT), we directly show that Sb2Te3 exhibits a partially occupied,\nsingle spin-Dirac cone around the Fermi energy, which is topologically\nprotected. DFT obtains a spin polarization of the occupied Dirac cone states of\n80-90%, which is in reasonable agreement with the experimental data after\ncareful background subtraction. Furthermore, we observe a strongly spin-orbit\nsplit surface band at lower energy. This state is found at 0.8eV below the\nFermi level at the gamma-point, disperses upwards, and disappears at about\n0.4eV below the Fermi level into two different bulk bands. Along the gamma-K\ndirection, the band is located within a spin-orbit gap. According to an\nargument given by Pendry and Gurman in 1975, such a gap must contain a surface\nstate, if it is located away from the high symmetry points of the Brillouin\nzone. Thus, the novel spin-split state is protected by symmetry, too."
    },
    {
        "anchor": "Crystallization in mass-asymmetric electron-hole bilayers: We consider a \\textit{mass-asymmetric} electron and hole bilayer. Electron\nand hole Coulomb correlations and electron and hole quantum effects are treated\non first princles by path integral Monte Carlo methods. For a fixed layer\nseparation we vary the mass ratio $M$ of holes and electrons between 1 and 100\nand analyze the structural changes in the system. While, for the chosen\ndensity, the electrons are in a nearly homogeneous state, the hole arrangement\nchanges from homogeneous to localized, with increasing $M$ which is verified\nfor both, mesoscopic bilayers in a parabolic trap and for a macroscopic system.",
        "positive": "Quantum tunneling of two coupled single-molecular magnets: Two single-molecule magnets are coupled antiferromagnetically to form a\nsupramolecule dimer. We study the coupling effect and tunneling process by\nmeans of the numerical exact diagonalization method, and apply them to the\nrecently synthesized supramoleculer dimer [Mn4]2 The model parameters are\ncalculated for the dimer based on the tunneling process. The absence of\ntunneling at zero field and sweeping rate effect on the step height in the\nhysterisis loops are understood very well in this theory."
    },
    {
        "anchor": "Photon statistics of radiation emitted by two quantum wells embedded in\n  two optically coupled semiconductor microcavities: We study theoretically the photon statistics of the field emitted from two\noptically coupled semiconductor microcavities each containing a quantum well.\nThe emission is determined by the interplay between exciton-photon coupling in\neach quantum well and internal interaction between the two optically coupled\nmicrocavities. A high degree of coherent control and tunability via the quantum\nwell-cavity coupling strength and photon tunneling over the photon statistics\nof the transmitted field can be achieved. We demonstrate that the optical\nproperty of radiation emitted by one quantum well can be controlled by the\nproperties of the second quantum well. This result has the potential to be used\nin quantum information processing. We show that the exciton-photon coupling\ninfluences the polariton resonances in the intensity spectrum of the\ntransmitted field. The results obtained in this investigation has the potential\nto be used for designing efficient controllable all-optical switch and high\nsensitive optical sensor.",
        "positive": "Wave function statistics and multifractality at the spin quantum Hall\n  transition: The statistical properties of wave functions at the critical point of the\nspin quantum Hall transition are studied. The main emphasis is put onto\ndetermination of the spectrum of multifractal exponents $\\Delta_q$ governing\nthe scaling of moments $<|\\psi|^{2q}>\\sim L^{-qd-\\Delta_q}$ with the system\nsize $L$ and the spatial decay of wave function correlations. Two- and\nthree-point correlation functions are calculated analytically by means of\nmapping onto the classical percolation, yielding the values $\\Delta_2=-1/4$ and\n$\\Delta_3=-3/4$. The multifractality spectrum obtained from numerical\nsimulations is given with a good accuracy by the parabolic approximation\n$\\Delta_q\\simeq q(1-q)/8$ but shows detectable deviations. We also study\nstatistics of the two-point conductance $g$, in particular, the spectrum of\nexponents $X_q$ characterizing the scaling of the moments $<g^q >$. Relations\nbetween the spectra of critical exponents of wave functions ($\\Delta_q$),\nconductances ($X_q$), and Green functions at the localization transition with a\ncritical density of states are discussed."
    },
    {
        "anchor": "Chirality relaxation in low-temperature strongly Rashba-coupled systems: We study the relaxation dynamics of non-equilibrium chirality distributions\nof charge carriers in Rashba systems. We find that at low temperature\ninter-Rashba band transitions become suppressed due to the combined effect of\nthe Rashba momentum split and the chiral spin texture of a Rashba system.\nSpecifically, we show that momentum exchange between carriers and the phonon\nbath is effectively absent at temperatures where the momentum of thermal\nphonons is less than twice the Rashba momentum. This allows us to identify\ninter-carrier scattering as the dominant process by which non-equilibrium\nchirality distributions relax. We show that the magnitude of inter-carrier\nscattering is strongly influenced by the opposing spin structure of the Rashba\nbands. Finally, we provide an explicit result for the inter-band relaxation\ntimescale associated with inter-carrier Coulomb scattering. We develop a\ngeneral framework and assess its implications for GeTe, a bulk Rashba\nsemiconductor with a strong Rashba momentum split.",
        "positive": "Quantum Effects in the Mechanical Properties of Suspended Nanomechanical\n  Systems: We explore the quantum aspects of an elastic bar supported at both ends and\nsubject to compression. If strain rather than stress is held fixed, the system\nremains stable beyond the buckling instability, supporting two potential\nminima. The classical equilibrium transverse displacement is analogous to a\nGinsburg-Landau order parameter, with strain playing the role of temperature.\nWe calculate the quantum fluctuations about the classical value as a function\nof strain. Excitation energies and quantum fluctuation amplitudes are compared\nfor silicon beams and carbon nanotubes."
    },
    {
        "anchor": "Bolometric detection of Josephson inductance in a highly resistive\n  environment: The Josephson junction is a building block of quantum circuits. Its behavior,\nwell understood when treated as an isolated entity, is strongly affected by\ncoupling to an electromagnetic environment. In 1983, Schmid predicted that a\nJosephson junction shunted by a resistance exceeding the resistance quantum\n$\\mathbf{\\textit{R}}_\\mathrm{Q} = h/4e^2 \\approx 6.45$ k$\\mathbf{\\Omega}$ for\nCooper pairs would become insulating since the phase fluctuations would destroy\nthe coherent Josephson coupling. However, recent microwave measurements have\nquestioned this interpretation. Here, we insert a small Josephson junction in a\nJohnson-Nyquist-type setup where it is driven by weak current noise arising\nfrom thermal fluctuations. Our heat probe minimally perturbs the junction's\nequilibrium, shedding light on features not visible in charge transport. We\nfind that the Josephson critical current completely vanishes in DC charge\ntransport measurement, and the junction demonstrates Coulomb blockade in\nagreement with the theory. Surprisingly, thermal transport measurements show\nthat the Josephson junction acts as an inductor at high frequencies,\nunambiguously demonstrating that a supercurrent survives despite the Coulomb\nblockade observed in DC measurements. The discrepancy between these two\nmeasurements highlights the difference between the low and the high frequency\nresponse of a junction and calls for further theoretical and experimental\ninputs on the dynamics of Josephson junctions \\textcolor{black}{operating at\nhigh frequencies in highly resistive environments.",
        "positive": "Impurities in a Biased Graphene Bilayer: We study the problem of impurities and mid-gap states in a biased graphene\nbilayer. We show that the properties of the bound states, such as localization\nlengths and binding energies, can be controlled externally by an electric field\neffect. Moreover, the band gap is renormalized and impurity bands are created\nat finite impurity concentrations. Using the coherent potential approximation\nwe calculate the electronic density of states and its dependence on the applied\nbias voltage."
    },
    {
        "anchor": "Surface reconstruction induced anisotropic energy landscape of bismuth\n  monomers and dimers on the Si(001) surface: Spin qubits have attracted tremendous attention in the effort of building\nquantum computers over the years. Natural atomic scale candidates are group-V\ndopants in silicon, not only showing ultra-long lifetimes but also being\ncompatible with current semiconductor technology. Nevertheless, bulk dopants\nare difficult to move with atomic precision, impeding the realization of\ndesired structures for quantum computing. A solution is to place the atom on\nthe surface which opens possibilities for atom level manipulations using\nscanning tunneling microscopy (STM). For this purpose, bismuth appears to be a\ngood candidate. Here, we use ab-initio methods to study theoretically the\nadsorption of bismuth atoms on the Si(001) surface and investigate the\nadsorption sites and the transitions between them. We demonstrate the complex\ninfluence of the dimer row surface reconstruction on the energy landscape seen\nby a bismuth monomer and a dimer on the surface, and find anisotropic\ntransition paths for movement on the surface. From a deposition simulation we\nobtain the expected occupation of adsorption sites. Our work lays the\nfoundation for further application of bismuth atoms as qubits on silicon\nsurfaces.",
        "positive": "Spin Resonance and dc Current Generation in a Quantum Wire: We show that in a quantum wire the spin-orbit interaction leads to a narrow\nspin resonance at low temperatures, even in the absence of an external magnetic\nfield. Resonance absorption by linearly polarized radiation gives a dc spin\ncurrent; resonance absorption by circularly polarized radiation gives a dc\nelectric current or magnetization."
    },
    {
        "anchor": "Spin and charge transport in topological nodal-line semimetals: We study transport properties of topological Weyl nodal-line\nsemimetals(NLSs). Starting from a minimal lattice model with a single nodal\nloop, and by focusing on a normal-metal-NLS-normal-metal junction, we\ninvestigate the dependence of the novel transport behavior on the orientation\nof the nodal loop. When the loop is parallel to the junction interfaces, the\ntransmitted current is found to be nearly fully spin-polarized.\nCorrespondingly, there exists a spin orientation, along which the incident\nelectrons would be totally reflected. An unusual resonance of half transmission\nwith the participation of surface states also occurs for a pair of incident\nelectrons with opposite spin orientations. All these phenomena have been shown\nto originate from the existence of a single forward-propagating mode in the NLS\nof the junction, and argued to survive in more generic multi-band Weyl NLSs.",
        "positive": "Magnetic properties of the $\u03b1$-$T_3$ model: magneto-optical\n  conductivity and the Hofstadter butterfly: The $\\alpha$-$T_3$ model extrapolates between the pseudospin $S=1/2$\nhoneycomb lattice of graphene and the pseudospin $S=1$ dice lattice via\nparameter $\\alpha$. We present calculations of the magnetic properties of this\nhybrid pseudospin model, namely the absorptive magneto-optical conductivity and\nthe Hofstadter butterfly spectra. In the magneto-optics curves, signatures of\nthe hybrid system corollary a doublet structure present in the peaks, resulting\nfrom differing Landau level energies in the $K$ and $K^{\\prime}$ valleys. In\nthe Hofstadter spectra, we detail the evolution of the Hofstadter butterfly as\nit changes its periodicity by a factor of three as we vary between the two\nlimiting cases of the $\\alpha$-$T_3$ model."
    },
    {
        "anchor": "Operating Principles of Vertical Transistors Based on Monolayer\n  Two-Dimensional Semiconductor Heterojunctions: A vertical transistor based on a double gated, atomically thin heterojunction\nis theoretically examined. Both p-type and n-type transistor operations can be\nconveniently achieved by using one of the two gates as the switching gate. The\ntransistor shows excellent saturation of output I-V characteristics due to\ndrain-induced depletion and lack of tunneling barrier layers. The subthreshold\nslope could be below the thermionic limit due to band filtering as the\nswitching mechanism. The atomically thin vertical PN heterojunction can be\nelectrostatically modulated from a type II heterojunction to a broken bandgap\nalignment, which is preferred for maximizing the on-current.",
        "positive": "Spin-wave dynamics in Permalloy/Cobalt magnonic crystals in the presence\n  of a non-magnetic spacer: In this paper, we theoretically study the influence of a non-magnetic spacer\nbetween ferromagnetic dots and ferromagnetic matrix on the frequency dispersion\nof the spin wave excitations in two-dimensional bi-component magnonic crystals.\nBy means of the dynamical matrix method we investigate structures inhomogeneous\nacross the thickness represented by square arrays of Cobalt or Permalloy dots\nin a Permalloy matrix. We show that the introduction of a non-magnetic spacer\nsignificantly modifies the total internal magnetic field especially at the\nedges of the grooves and dots. This permits the manipulation of the magnonic\nband structure of spin waves localized either at the edges of the dots or in\nmatrix material at the edges of grooves. According to the micromagnetic\nsimulations two types of end modes were found. The corresponding frequencies\nare significantly influenced by the end modes localization region. We also show\nthat, with the use of a single ferromagnetic material, it is possible to design\na magnonic crystal preserving properties of bi-component magnonic crystals and\nmagnonic antidot lattices. Finally, the influence of the non-magnetic spacers\non the technologically relevant parameters like group velocity and magnonic\nband width are discussed."
    },
    {
        "anchor": "Enrichment of Armchair Carbon Nanotubes via Density Gradient\n  Ultracentrifugation: Raman Spectroscopy Evidence: We have used resonant Raman scattering spectroscopy to fully analyze the\nrelative abundances of different (n,m) species in single-walled carbon nanotube\nsamples that are metallically enriched by density gradient ultracentrifugation.\nStrikingly, the data clearly show that our density gradient ultracentrifugation\nprocess enriches the metallic fractions in armchair and near-armchair species.\nWe observe that armchair carbon nanotubes constitute more than 50% of each (2n\n+ m) family.",
        "positive": "Valley-Polarized Quantum Transport Generated by Gauge Fields in Graphene: We report on the possibility to simultaneously generate in graphene a {\\it\nbulk valley-polarized dissipative transport} and a {\\it quantum valley Hall\neffect} by combining strain-induced gauge fields and real magnetic fields. Such\nunique phenomenon results from a resonance/anti-resonance effect driven by the\nsuperposition/cancellation of superimposed gauge fields which differently\naffect time reversal symmetry. The onset of a valley-polarized Hall current\nconcomitant to a dissipative valley-polarized current flow in the opposite\nvalley is revealed by a $e^2/h$ Hall conductivity plateau. We employ efficient\nlinear scaling Kubo transport methods combined with a valley projection scheme\nto access valley-dependent conductivities and show that the results are robust\nagainst disorder."
    },
    {
        "anchor": "Equations of Motion and Frequency Dependence of Magnon-Induced Domain\n  Wall Motion: Spin waves can induce domain wall motion in ferromagnets. We derive the\nequations of motion for a transverse domain wall driven by spin waves. Our\ncalculations show that the magnonic spin-transfer torque does not cause\nrotation-induced Walker breakdown. The amplitude of spin waves that are excited\nby a localized microwave field depends on the spatial profile of the field and\nthe excitation frequency. By taking this frequency dependence into account, we\nshow that a simple one-dimensional model may reproduce much of the puzzling\nfrequency dependence observed in early numerical studies.",
        "positive": "Correlated electrons in optically-tunable quantum dots: Building an\n  electron dimer molecule: We observe the low-lying excitations of a molecular dimer formed by two\nelectrons in a GaAs semiconductor quantum dot in which the number of confined\nelectrons is tuned by optical illumination. By employing inelastic light\nscattering we identify the inter-shell excitations in the one-electron regime\nand the distinct spin and charge modes in the interacting few-body\nconfiguration. In the case of two electrons a comparison with\nconfiguration-interaction calculations allows us to link the observed\nexcitations with the breathing mode of the molecular dimer and to determine the\nsinglet-triplet energy splitting."
    },
    {
        "anchor": "Out-of-equilibrium Kondo Effect in a Quantum Dot: Interplay of Magnetic\n  Field and Spin Accumulation: We present a theoretical study of low temperature nonequilibrium transport\nthrough an interacting quantum dot in the presence of Zeeman magnetic field and\ncurrent injection into one of its leads. By using a self-consistent\nrenormalized equation of motion approach, we show that the injection of a\nspin-polarized current leads to a modulation of the Zeeman splitting of the\nKondo peak in the differential conductance. We find that an appropriate amount\nof spin accumulation in the lead can restore the Kondo peak by compensating the\nsplitting due to magnetic field. By contrast when the injected current is\nspin-unpolarized, we establish that both Zeeman-split Kondo peaks are equally\nshifted and the splitting remains unchanged. Our results quantitatively explain\nthe experimental findings reported in KOBAYASHI T. et al., Phys. Rev. Lett.\n104, 036804 (2010). These features could be nicely exploited for the control\nand manipulation of spin in nanoelectronic and spintronic devices.",
        "positive": "Thermal Conductivity of Suspended Few-Layer MoS2: Modifying phonon thermal conductivity in nanomaterials is important not only\nfor fundamental research but also for practical applications. However, the\nexperiments on tailoring the thermal conductivity in nanoscale, especially in\ntwo-dimensional materials, are rare due to technical challenges. In this work,\nwe demonstrate in-situ thermal conduction measurement of MoS2 and find that its\nthermal conductivity can be continuously tuned to a required value from\ncrystalline to amorphous limits. The reduction of thermal conductivity is\nunderstood from phonon-defects scatterings that decrease the phonon\ntransmission coefficient. Beyond a threshold, a sharp drop in thermal\nconductivity is observed, which is believed to be a crystalline-amorphous\ntransition. Our method and results provide guidance for potential applications\nin thermoelectrics, photoelectronics, and energy harvesting where thermal\nmanagement is critical with further integration and miniaturization."
    },
    {
        "anchor": "Transport of fullerene molecules along graphene nanoribbons: We study the motion of C60 fullerene molecules (buckyballs) and short-length\ncarbon nanotubes on graphene nanoribbons. We demonstrate that the nanoribbon\nedge creates an effective potential that keeps the carbon structures on the\nsurface. We reveal that the character of the motion of C60 molecules depends on\ntemperature: for low temperatures (T<150K) the main type of motion is sliding\nalong the surface, but for higher temperatures the sliding is replaced by\nrocking and rolling. Modeling of the buckyball with an included metal ion, such\nas Fe@C60, demonstrates that this molecular complex undergoes a rolling motion\nalong the nanoribbon with the constant velocity under the action of a constant\nelectric field. The similar effect is observed in the presence of the heat\ngradient applied to the nanoribbon, but mobility of carbon structures in this\ncase depends largely on their size and symmetry, such that larger and more\nasymmetric structures demonstrate much lower mobility. Our results suggest that\nboth electorphoresis and thermophoresis can be employed to control the motion\nof carbon molecules and fullerenes and, for example, sort them by their size,\nshape, and possible inclusions.",
        "positive": "Nonrelaxational FMR peak broadening in spatially inhomogeneous films: The modification of magnetic properties in spatially inhomogeneous epitaxial\nfilms of magnetic shape memory alloys in martensitic state with the temperature\nvariation has been studied. The proposed theoretical model is based on Landau\ntheory of martensitic transformation and statistical model of martensitic\nstate. It was shown that that spatial inhomogeneity of the material leads to\nthe dispersion of local martensitic transformation temperatures resulting in\nthe variation of local magnetic anisotropy values. This model allows describing\nthe dramatic ferromagnetic resonance line broadening observed in the\nexperiments in epitaxial films of magnetic shape memory alloys at low\ntemperatures."
    },
    {
        "anchor": "Giant asymmetric proximity-induced spin-orbit coupling in twisted\n  graphene/SnTe heterostructure: We analyze the spin-orbit coupling effects in a three-degree twisted bilayer\nheterostructure made of graphene and an in-plane ferroelectric SnTe, with the\ngoal of transferring the spin-orbit coupling from SnTe to graphene, via the\nproximity effect. Our results indicate that the point-symmetry breaking due to\nthe incompatible mutual symmetry of the twisted monolayers and a strong\nhybridization has a massive impact on the spin splitting in graphene close to\nthe Dirac point, with the spin splitting values greater than 20 meV. The band\nstructure and spin expectation values of graphene close to the Dirac point can\nbe described using a symmetry-free model, triggering different types of\ninteraction with respect to the threefold symmetric graphene/transition-metal\ndichalcogenide heterostructure. We show that the strong hybridization of the\nDirac cone's right movers with the SnTe band gives rise to a large asymmetric\nspin splitting in the momentum space. Furthermore, we discover that the\nferroelectricity-induced Rashba spin-orbit coupling in graphene is the dominant\ncontribution to the overall Rashba field, with the effective in-plane electric\nfield that is almost aligned with the (in-plane) ferroelectricity direction of\nthe SnTe monolayer. We also predict an anisotropy of the in-plane spin\nrelaxation rates. Our results demonstrate that the group-IV monochalcogenides\nMX (M=Sn, Ge; X=S, Se, Te) are a viable alternative to transition-metal\ndichalcogenides for inducing strong spin-orbit coupling in graphene.",
        "positive": "Magneto-spectroscopy of exciton Rydberg states in a CVD grown WSe2\n  monolayer: The results of magneto-optical spectroscopy investigations of excitons in a\nCVD grown monolayer of WSe2 encapsulated in hexagonal boron nitride are\npresented. The emission linewidth for the 1s state is of 4:7 meV, close to the\nnarrowest emissions observed in monolayers exfoliated from bulk material. The\n2s excitonic state is also observed at higher energies in the photoluminescence\nspectrum. Magneto-optical spectroscopy allows for the determination of the\ng-factors and of the spatial extent of the excitonic wave functions associated\nwith these emissions. Our work establishes CVD grown monolayers of transition\nmetal dichalcogenides as a mature technology for optoelectronic applications."
    },
    {
        "anchor": "Positive Magneto-conductivity of Weyl Semimetals in the Ultra-quantum\n  Limit: In this paper, we numerically study the magnetic transport properties of\ndisordered Weyl semimetals (WSM) in the ultra-quantum limit. We find a positive\nmagnetic conductivity for the long-range disorder, although the system tends to\nhave negative magnetic conductivity for the weak short-range disorder.\nRemarkably, for long-range disorder, such a positive magnetic conductivity\ncannot be described by the semiclassical Boltzmann transport theory even in the\nweak disorder limit, and the back-scattering assisted by the high Landau levels\nis always important. Our results have significant implications for the positive\nmagnetic conductivity recently discovered in the WSM systems, and point out two\nphysical mechanisms: (i) the long-range correlated disorder suppresses the\nback-scattering among the zeroth Landau level modes; (ii) with increasing the\nmagnetic field, the back-scattering assisted by the high Landau levels will\nalso be suppressed.",
        "positive": "Cavity quantum electrodynamics with semiconductor quantum dots: The role\n  of phonon-assisted cavity feeding: For a semiconductor quantum dot strongly coupled to a microcavity, we\ntheoretically investigate phonon-assisted transitions from the exciton to a\ncavity photon, where the energy mismatch is compensated by phonon emission or\nabsorption. By means of a Schrieffer-Wolff transformation we derive an\neffective Hamiltonian, which describes the combined effect of exciton-cavity\nand exciton-phonon coupling, and compute the scattering rates within a Fermi\ngolden rule approach. The results of this approach are compared with those of a\nrecently reported description scheme based on the independent Boson model [U.\nHohenester et al., Phys. Rev. B 80, 201311(R) (2009)], and a numerical density\nmatrix approach. All description schemes are shown to give very similar\nresults. We present results for the spontaneous emission lifetime of a quantum\ndot initially populated with a single exciton or biexciton, and for the\nspectral properties of an optically driven dot-cavity system operating in the\nstrong coupling regime. Our results demonstrate that phonon-assisted feeding\nplays a dominant role for strongly coupled dot-cavity systems, when the\ndetuning is of the order of a few millielectron volts."
    },
    {
        "anchor": "In-plane magnetic field-induced spin polarization and transition to\n  insulating behavior in two-dimensional hole systems: Using a novel technique, we make quantitative measurements of the spin\npolarization of dilute (3.4 to 6.8*10^{10} cm^{-2}) GaAs (311)A two-dimensional\nholes as a function of an in-plane magnetic field. As the field is increased\nthe system gradually becomes spin polarized, with the degree of spin\npolarization depending on the orientation of the field relative to the crystal\naxes. Moreover, the behavior of the system turns from metallic to insulating\n\\textit{before} it is fully spin polarized. The minority-spin population at the\ntransition is ~8*10^{9} cm^{-2}, close to the density below which the system\nmakes a transition to an insulating state in the absence of a magnetic field.",
        "positive": "Magnonic band structure in a Co/Pd stripe domain system investigated by\n  Brillouin light scattering and micromagnetic simulations: By combining Brillouin Light Scattering and micromagnetic simulations we\nstudied the spin-wave dynamics of a Co/Pd thin film multilayer, features a\nstripe domain structure at remanence. The periodic up and down domains are\nseparated by cork-screw type domain walls. The existence of these domains\ncauses a scattering of the otherwise bulk and surface spin-wave modes, which\nform mode families, similar to a one dimensional magnonic crystal. The\ndispersion relation and mode profiles of spin waves are measured for\ntransferred wave vector parallel and perpendicular to the domain axis."
    },
    {
        "anchor": "Spin-thermo-electronic oscillator based on inverse giant\n  magnetoresistance: A spin-thermo-electronic valve with the free layer of exchange-spring type\nand inverse magnetoresistance is investigated. The structure has S-shaped\ncurrent-voltage characteristics and can exhibit spontaneous oscillations when\nintegrated with a conventional capacitor within a resonator circuit. The\nfrequency of the oscillations can be controlled from essentially dc to the GHz\nrange by the circuit capacitance.",
        "positive": "Electrical Contacts to Three-Dimensional Arrays of Carbon Nanotubes: We use numerical simulations to investigate the properties of metal contacts\nto three-dimensional arrays of carbon nanotubes (CNTs). For undoped arrays\ntop-contacted with high or low work function metals, electrostatic screening is\nvery strong, resulting in a small Schottky barrier for current injection in the\ntop layer and large Schottky barriers for current injection in the deeper\nlayers. As a consequence, the majority of the current flows through the top\nlayer of the array. Our simulations show that doping of the CNT array can\nalleviate this problem, even without direct contact to each tube in the array;\nhowever, we find that the charge transfer length is unusually long in arrays\nand increases with the number of CNT layers under the contact. We also show\nthat a bottom gate can modulate the contact resistance, but only very weakly.\nThese results are important for the design of electronic and optoelectronic\ndevices based on CNT arrays, because they suggest that increasing the thickness\nof the array does little to improve the device performance unless the film is\nstrongly doped at the contacts and the contact is long, or unless each tube in\nthe array is directly contacted by the metal."
    },
    {
        "anchor": "Dynamic current susceptibility as a probe of Majorana bound states in\n  nanowire-based Josephson junctions: We theoretically study a Josephson junction based on a semiconducting\nnanowire subject to a time-dependent flux bias. We establish a general density\nmatrix approach for the dynamical response of the Majorana junction and\ncalculate the resulting flux-dependent susceptibility using both microscopic\nand effective low-energy descriptions for the nanowire. We find that the\ndiagonal component of the susceptibility, associated with the dynamics of the\nMajorana states populations, dominates over the standard Kubo contribution for\na wide range of experimentally relevant parameters. The diagonal term, thus far\nunexplored in the context of Majorana physics, allows to probe accurately the\npresence of Majorana bound states in the junction.",
        "positive": "Magnetization distribution and domain wall dynamics in nanotube with\n  surface anisotropy: The period of magnetization oscillations that occur near the surface of a\nnanotube or nanowire under the influence of surface magnetic anisotropy is\ndetermined by means of numerical simulation as a function of nanowire geometry\nand material parameters. The hopping mode is observed for stationary movement\nof a head-to-head domain wall along nanowire axis in applied magnetic field.\nThe average speed of the domain wall in the hopping mode is found to be several\ntimes less than the stationary velocity of the wall in the absence of surface\nanisotropy."
    },
    {
        "anchor": "Superfluidity of \"dirty\" indirect excitons in coupled quantum wells: The theory of what happens to a superfluid in a random field, known as the\n``dirty boson'' problem, directly relates to a real experimental system\npresently under study by several groups, namely excitons in coupled\nsemiconductor quantum wells. We consider the case of bosons in two dimensions\nin a random field, when the random field can be large compared to the repulsive\nexciton-exciton interaction energy, but is small compared to the exciton\nbinding energy. The interaction between excitons is taken into account in the\nladder approximation. The coherent potential approximation allows us to derive\nthe exciton Green's function for a wide range of the random field strength, and\nin the weak-scattering limit CPA results in the second-order Born\napproximation. For quasi-two-dimensional excitonic systems, the density of the\nsuperfluid component and the Kosterlitz-Thouless temperature of the superfluid\nphase transition are obtained, and are found to decrease as the random field\nincreases.",
        "positive": "Light-enhanced nonlinear Hall effect: It is well known that a nontrivial Chern number results in quantized Hall\nconductance. What is less known is that, generically, the Hall response can be\ndramatically different from its quantized value in materials with broken\ninversion symmetry. This stems from the leading Hall contribution beyond the\nlinear order, known as the Berry curvature dipole (BCD). While the BCD is in\nprinciple always present, it is typically very small outside of a narrow window\nclose to a topological transition and is thus experimentally elusive without\ncareful tuning of external fields, temperature, or impurities. In this work, we\ntranscend this challenge by devising optical driving and quench protocols that\nenable practical and direct access to large BCD and nonlinear Hall responses.\nVarying the amplitude of an incident circularly polarized laser drives a\ntopological transition between normal and Chern insulator phases, and\nimportantly allows the precise unlocking of nonlinear Hall currents comparable\nto or larger than the linear Hall contributions. This strong BCD engineering is\neven more versatile with our two-parameter quench protocol, as demonstrated in\nour experimental proposal. Our predictions are expected to hold qualitatively\nacross a broad range of Hall materials, thereby paving the way for the\ncontrolled engineering of nonlinear electronic properties in diverse media."
    },
    {
        "anchor": "Forbidden Backscattering and Resistance Dip in the Quantum Limit as a\n  Signature for Topological Insulators: Identifying topological insulators and semimetals often focuses on their\nsurface states, using spectroscopic methods such as angle-resolved\nphotoemission spectroscopy or scanning tunneling microscopy. In contrast,\nstudying the topological properties of topological insulators from their\nbulk-state transport is more accessible in most labs but seldom addressed. We\nshow that, in the quantum limit of a topological insulator, the backscattering\nbetween the only two states on the Fermi surface of the lowest Landau band can\nbe forbidden, at a critical magnetic field. The conductivity is determined\nsolely by the backscattering between the two states, leading to a resistance\ndip that may serve as a signature for topological insulator phases. More\nimportantly, this forbidden backscattering mechanism for the resistance dip is\nirrelevant to details of disorder scattering. Our theory can be applied to\nrevisit the experiments on Pb$_{1-x}$Sn$_x$Se, ZrTe$_5$, and Ag$_2$Te families,\nand will be particularly useful for controversial small-gap materials at the\nboundary between topological and normal insulators.",
        "positive": "Quantum Hall - insulator transitions in lattice models with strong\n  disorder: We report results of numerical studies of the integer quantum Hall effect in\na tight binding model on a two-dimensional square lattice with non-interacting\nelectrons, in the presence of a random potential as well as a uniform magnetic\nfield applied perpendicular to the lattice. We consider field magnitudes such\nthat the area per flux quantum is commensurate with the lattice structure.\nTopological properties of the single electron wave functions are used to\nidentify current carrying states that are responsible for the quantized Hall\nconductance. We study the interplay between the magnetic field and the\ndisorder, and find a universal pattern with which the current carrying states\nare destroyed by increasing disorder strength, and the system driven into an\ninsulating state. We also discuss how to interpolate results of lattice models\nto the continuum limit. The relationship to previous theoretical and\nexperimental studies of quantum Hall-insulator transitions in strongly\ndisordered systems at low magnetic fields is discussed."
    },
    {
        "anchor": "Intrinsic topological phases in Mn$_2$Bi$_2$Te$_5$ tuned by the layer\n  magnetization: The interplay between band topology and magnetic order could generate a\nvariety of time-reversal-breaking gapped topological phases with exotic\ntopological quantization phenomena, such as quantum anomalous Hall (QAH)\ninsulators and axion insulators (AxI). Here by combining analytic models and\nfirst-principles calculations, we predict QAH and AxI phases can be realized in\nthin film of an intrinsic antiferromagnetic van der Waal material\nMn$_2$Bi$_2$Te$_5$. The phase transition between QAH and AxI is tuned by the\nlayer magnetization, which would provide a promising platform for chiral\nsuperconducting phases. We further present a simple and unified continuum model\nthat captures the magnetic topological features, and is generic for\nMn$_2$Bi$_2$Te$_5$ and MnBi$_2$Te$_4$ family materials.",
        "positive": "Transitions between \"$\u03c0$\" and \"0\" states in superconductor --\n  ferromagnet -- superconductor junctions: Experimental and theoretical study of superconductor (S) -- ferromagnet (F)\n-- superconductor junctions showed that in certain range of parameters (e.g.,\nthe length of the ferromagnet $d_F$, the exchange field, $E_{\\rm ex}$) the\nground state of a SFS junction corresponds to superconducting phase difference\n$\\pi$ or 0. The phase diagram of a SFS junction with the respect to $\\pi$ and 0\nstates is investigated in this letter in $E_{\\rm ex}, d_{F}, T$ space. It is\nshown that the phase diagram is very sensitive to the geometry of the system,\nin particular, to the amount of disorder."
    },
    {
        "anchor": "Crossover between fast and slow excitation of magnetization by spin\n  torque: A crossover between two mechanisms destabilizing the magnetization in\nequilibrium by the spin transfer effect is found in a ferromagnetic multilayer\nconsisting of an in-plane magnetized free layer and a perpendicularly\nmagnetized pinned layer, where an in-plane magnetic field is applied, and\nelectric current flows from the pinned to the free layer. A fast transition\nfrom the in-plane to the out-of-plane state occurs in the low-field region,\nwhereas a slow transition with small-amplitude oscillation becomes dominant in\nthe high-field region. On the other hand, only the fast transition mechanism\nappears for the opposite current direction.",
        "positive": "Entanglement entropy and entanglement spectrum of Bi$_{1-x}$Sb$_{x}$\n  (111) bilayers: We investigate topological properties of Bi$_{1-x}$Sb$_{x}$ bilayers in the\n(111) plane using entanglement measures. Electronic structures are studied\nusing multi-orbital tight-binding model, with structural stability confirmed\nthrough first-principles calculations. Topologically non-trivial nature of Bi\nbilayer is proved by the presence of spectral flow in the entanglement\nspectrum. We consider topological phase transitions driven by a composition\nchange $x$, an applied external electric field in pure Bi, and strain in pure\nSb. Composition- and strain-induced phase transitions reveal a finite\ndiscontinuity in the entanglement entropy. However, this quantity remains a\ncontinuous function of electric field strength, but shows a discontinuity in\nthe first derivative. We relate the difference in behavior of the entanglement\nentropy to breaking of the inversion symmetry in the last case."
    },
    {
        "anchor": "Reconfigurable magnonic mode-hybridisation and spectral control in a\n  bicomponent artificial spin ice: Strongly-interacting nanomagnetic arrays are finding increasing use as model\nhost systems for reconfigurable magnonics. The strong inter-element coupling\nallows for stark spectral differences across a broad microstate space due to\nshifts in the dipolar field landscape. While these systems have yielded\nimpressive initial results, developing rapid, scaleable means to access abroad\nrange of spectrally-distinct microstates is an open research problem.We present\na scheme whereby square artificial spin ice is modified by widening a\n'staircase' subset of bars relative to the rest of the array, allowing\npreparation of any ordered vertex state via simple global-field protocols.\nAvailable microstates range from the system ground-state to high-energy\n'monopole' states, with rich and distinct microstate-specific magnon spectra\nobserved. Microstate-dependent mode-hybridisation and anticrossings are\nobserved at both remanence and in-field with dynamic coupling strength tunable\nvia microstate-selection. Experimental coupling strengths are found up to g /\n2$\\pi$ = 0.15 GHz. Microstate control allows fine mode-frequency shifting, gap\ncreation and closing, and active mode number selection.",
        "positive": "Coupled spin states in armchair graphene nanoribbons with asymmetric\n  zigzag edge extensions: Carbon-based magnetic structures promise significantly longer coherence times\nthan traditional magnetic materials, which is of fundamental importance for\nspintronic applications. An elegant way of achieving carbon-based magnetic\nmoments is the design of graphene nanostructures with an imbalanced occupation\nof the two sublattices forming the carbon honeycomb lattice. According to\nLieb's theorem, this induces local magnetic moments that are proportional to\nthe sublattice imbalance. Exact positioning of sublattice imbalanced\nnanostructures in graphene nanomaterials hence offers a route to control\ninteractions between induced local magnetic moments and to obtain graphene\nnanomaterials with magnetically non-trivial ground states. Here, we show that\nsuch sublattice imbalanced nanostructures can be incorporated along a large\nband gap armchair graphene nanoribbon on the basis of asymmetric zigzag edge\nextensions, which is achieved by incorporating specifically designed precursor\nmonomers during the bottom-up fabrication of the graphene nanoribbons. Scanning\ntunneling spectroscopy of an isolated and electronically decoupled zigzag edge\nextension reveals Hubbard-split states in accordance with theoretical\npredictions. Investigation of pairs of such zigzag edge extensions reveals\nferromagnetic, antiferromagnetic or quenching of the magnetic interactions\ndepending on the relative alignment of the asymmetric edge extensions.\nMoreover, a ferromagnetic spin chain is demonstrated for a periodic pattern of\nzigzag edge extensions along the nanoribbon axis. This work opens a route\ntowards the design and fabrication of graphene nanoribbon-based spin chains\nwith complex magnetic ground states."
    },
    {
        "anchor": "Microscopic Theory of Rashba Interaction in Magnetic Metal: Theory of Rashba spin-orbit coupling in magnetic metals is worked out from\nmicroscopic Hamiltonian describing d-orbitals. When structural inversion\nsymmetry is broken, electron hopping between $d$-orbitals generates chiral\nordering of orbital angular momentum, which combines with atomic spin-orbit\ncoupling to result in the Rashba interaction. Rashba parameter characterizing\nthe interaction is band-specific, even reversing its sign from band to band.\nLarge enhancement of the Rashba parameter found in recent experiments is\nattributed to the orbital mixing of 3d magnetic atoms with non-magnetic heavy\nelements as we demonstrate by first-principles and tight-binding calculations.",
        "positive": "Drude weight in systems with open boundary conditions: A many-electron conducting system undergoes free acceleration in response to\na macroscopic field. The Drude weight $D$---also called charge\nstiffness---measures the adiabatic (inverse) inertia of the electrons; the $D$\nformal expression requires periodic boundary conditions. When instead a bounded\nsample is addressed within open boundary conditions, no current flows and a\nconstant (external) field only polarizes the sample: the Faraday cage effect.\nNonetheless a low-frequency field induces forced oscillations: we show here\nthat the low-frequency linear response of the bounded system is dominated by\nthe adiabatic inertia and allows an alternative evaluation of $D$. Simulations\non model one-dimensional systems demonstrate our main message."
    },
    {
        "anchor": "Gate-induced blueshift and quenching of photoluminescence in suspended\n  single-walled carbon nanotubes: Gate-voltage effects on photoluminescence spectra of suspended single-walled\ncarbon nanotubes are investigated. Photoluminescence microscopy and excitation\nspectroscopy are used to identify individual nanotubes and to determine their\nchiralities. Under an application of gate voltage, we observe slight blueshifts\nin the emission energy and strong quenching of photoluminescence. The\nblueshifts are similar for different chiralities investigated, suggesting\nextrinsic mechanisms. In addition, we find that the photoluminescence intensity\nquenches exponentially with gate voltage.",
        "positive": "Optical detection and manipulation of spontaneous gyrotropic electronic\n  order in a transition-metal dichalcogenide semimetal: The observation of chirality is ubiquitous in nature. Contrary to intuition,\nthe population of opposite chiralities is surprisingly asymmetric at\nfundamental levels. Examples range from parity violation in the subatomic weak\nforce to the homochirality in essential biomolecules. The ability to achieve\nchirality-selective synthesis (chiral induction) is of great importance in\nstereochemistry, molecular biology and pharmacology. In condensed matter\nphysics, a crystalline electronic system is geometrically chiral when it lacks\nany mirror plane, space inversion center or roto-inversion axis. Typically, the\ngeometrical chirality is predefined by a material's chiral lattice structure,\nwhich is fixed upon the formation of the crystal. By contrast, a particularly\nunconventional scenario is the gyrotropic order, where chirality spontaneously\nemerges across a phase transition as the electron system breaks the relevant\nsymmetries of an originally achiral lattice. Such a gyrotropic order, proposed\nas the quantum analogue of the cholesteric liquid crystals, has attracted\nsignificant interest. However, to date, a clear observation and manipulation of\nthe gyrotropic order remain challenging. We report the realization of optical\nchiral induction and the observation of a gyrotropically ordered phase in the\ntransition-metal dichalcogenide semimetal $1T$-TiSe$_2$. We show that shining\nmid-infrared circularly polarized light near the critical temperature leads to\nthe preferential formation of one chiral domain. As a result, we are able to\nobserve an out-of-plane circular photogalvanic current, whose direction depends\non the optical induction. Our study provides compelling evidence for the\nspontaneous emergence of chirality in the correlated semimetal TiSe$_2$. Such\nchiral induction provides a new way of optical control over novel orders in\nquantum materials."
    },
    {
        "anchor": "Finite size bath in qubit thermodynamics: We discuss a qubit weakly coupled to a finite-size heat bath (calorimeter)\nfrom the point of view of quantum thermodynamics. The energy deposited to this\nenvironment together with the state of the qubit provides a basis to analyze\nthe heat and work statistics of this closed combined system. We present results\non two representative models, where the bath is composed of two-level systems\nor harmonic oscillators, respectively. Finally, we derive results for an open\nquantum system composed of the above qubit plus finite-size bath, but now the\nlatter is coupled to a practically infinite bath of the same nature of\noscillators or two-level systems.",
        "positive": "Hybridization of sub-gap states in one-dimensional\n  superconductor/semiconductor Coulomb islands: We present measurements of one-dimensional superconductor-semiconductor\nCoulomb islands, fabricated by gate confinement of a two-dimensional InAs\nheterostructure with an epitaxial Al layer. When tuned via electrostatic side\ngates to regimes without sub-gap states, Coulomb blockade reveals Cooper-pair\nmediated transport. When sub-gap states are present, Coulomb peak positions and\nheights oscillate in a correlated way with magnetic field and gate voltage, as\npredicted theoretically, with (anti) crossings in (parallel) transverse\nmagnetic field indicating Rashba-type spin-orbit coupling. Overall results are\nconsistent with a picture of overlapping Majorana zero modes in finite wires."
    },
    {
        "anchor": "Visualization of phase-coherent electron interference in a ballistic\n  graphene Josephson junction: Interference of standing waves in electromagnetic resonators forms the basis\nof many technologies, from telecommunications and spectroscopy to detection of\ngravitational waves. However, unlike the confinement of light waves in vacuum,\nthe interference of electronic waves in solids is complicated by boundary\nproperties of the crystal, notably leading to electron guiding by atomic-scale\npotentials at the edges. Understanding the microscopic role of boundaries on\ncoherent wave interference is an unresolved question due to the challenge of\ndetecting charge flow with submicron resolution. Here we employ Fraunhofer\ninterferometry to achieve real-space imaging of cavity modes in a graphene\nFabry-Perot resonator, embedded between two superconductors to form a Josephson\njunction. By directly visualizing current flow using Fourier methods, our\nmeasurements reveal surprising redistribution of current on and off resonance.\nThese findings provide direct evidence of separate interference conditions for\nedge and bulk currents and reveal the ballistic nature of guided edge states.\nBeyond equilibrium, our measurements show strong modulation of the multiple\nAndreev reflection amplitude on an off resonance, a direct measure of the\ngate-tunable change of cavity transparency. These results demonstrate that,\ncontrary to the common belief, electron interactions with realistic disordered\nedges facilitate electron wave interference and ballistic transport.",
        "positive": "Origin of Rashba-splitting in the quantized subbands at Bi2Se3 surface: We study the band structure of the $\\text{Bi}_2\\text{Se}_3$ topological\ninsulator (111) surface using angle-resolved photoemission spectroscopy. We\nexamine the situation where two sets of quantized subbands exhibiting different\nRashba spin-splitting are created via bending of the conduction (CB) and the\nvalence (VB) bands at the surface. While the CB subbands are strongly Rashba\nspin-split, the VB subbands do not exhibit clear spin-splitting. We find that\nCB and VB experience similar band bending magnitudes, which means, a\nspin-splitting discrepancy due to different surface potential gradients can be\nexcluded. On the other hand, by comparing the experimental band structure to\nfirst principles LMTO band structure calculations, we find that the strongly\nspin-orbit coupled Bi 6$p$ orbitals dominate the orbital character of CB,\nwhereas their admixture to VB is rather small. The spin-splitting discrepancy\nis, therefore, traced back to the difference in spin-orbit coupling between CB\nand VB in the respective subbands' regions."
    },
    {
        "anchor": "Enhanced current rectification in graphene nanoribbons: Effects of\n  geometries and orientations of nanopores: We discuss the possibility of getting rectification operation in graphene\nnanoribbon (GNR). For a system to be a rectifier, it must be physically\nasymmetric and we induce the asymmetry in GNR by introducing nanopores. The\nrectification properties are discussed for differently structured nanopores. We\nfind that shape and orientation of the nanopores are critical and sensitive to\nthe degree of current rectification. As the choice of Fermi energy is crucial\nfor obtaining significant current rectification, explicit dependence of Fermi\nenergy on the degree of current rectification is also studied for a particular\nshape of the nanopore. Finally, the role of nanopore size and different spatial\ndistributions of the electrostatic potential profile across the GNR are\ndiscussed. Given the simplicity of the proposed method and promising results,\nthe present proposition may lead to a new route of getting current\nrectification in different kinds of materials where nanopores can be formed\nselectively.",
        "positive": "Nonlinear spectra of spinons and holons in short GaAs quantum wires: One-dimensional electronic fluids are peculiar conducting systems, where the\nfundamental role of interactions leads to exotic, emergent phenomena, such as\nspin-charge (spinon-holon) separation. The distinct low-energy properties of\nthese 1D metals are successfully described within the theory of linear\nLuttinger liquids, but the challenging task of describing their high-energy\nnonlinear properties has long remained elusive. Recently, novel theoretical\napproaches accounting for nonlinearity have been developed, yet the rich\nphenomenology that they predict remains barely explored experimentally. Here,\nwe probe the nonlinear spectral characteristics of short GaAs quantum wires by\ntunnelling spectroscopy, using an advanced device consisting of 6000 wires. We\nfind evidence for the existence of an inverted (spinon) shadow band in the main\nregion of the particle sector, one of the central predictions of the new\nnonlinear theories. A (holon) band with reduced effective mass is clearly\nvisible in the particle sector at high energies."
    },
    {
        "anchor": "Circuit Theory for SPICE of Spintronic Integrated Circuits: We present a theoretical and a numerical formalism for analysis and design of\nspintronic integrated circuits (SPINICs). The formalism encompasses a\ngeneralized circuit theory for spintronic integrated circuits based on\nnanomagnetic dynamics and spin transport. We propose an extension to the\nModified Nodal Analysis technique for the analysis of spin circuits based on\nthe recently developed spin conduction matrices. We demonstrate the\napplicability of the framework using an example spin logic circuit described\nusing spin Netlists.",
        "positive": "Radius dependent shift of surface plasmon frequency in large metallic\n  nanospheres: theory and experiment: Theoretical description of oscillations of electron liquid in large metallic\nnanospheres (with radius of few tens nm) is formulated within\nrandom-phase-approximation semiclassical scheme. Spectrum of plasmons is\ndetermined including both surface and volume type excitations. It is\ndemonstrated that only surface plasmons of dipole type can be excited by\nhomogeneous dynamical electric field. The Lorentz friction due to irradiation\nof electro-magnetic wave by plasmon oscillations is analyzed with respect to\nthe sphere dimension. The resulting shift of resonance frequency turns out to\nbe strongly sensitive to the sphere radius. The form of e-m response of the\nsystem of metallic nanospheres embedded in the dielectric medium is found. The\ntheoretical predictions are verified by a measurement of extinction of light\ndue to plasmon excitations in nanosphere colloidal water solutions, for Au and\nAg metallic components with radius from 10 to 75 nm. Theoretical predictions\nand experiments clearly agree in the positions of surface plasmon resonances\nand in an emergence of the first volume plasmon resonance in the e-m response\nof the system for limiting big nanosphere radii, when dipole approximation is\nnot exact."
    },
    {
        "anchor": "Magnetomotive Instability and Generation of Mechanical Vibrations in\n  Suspended Semiconducting Carbon Nanotubes: We have theoretically investigated the electromechanical properties of a\nfreely suspended carbon nanotube that is connected to a constant-current source\nand subjected to an external magnetic field. We show that self-excitation of\nmechanical vibrations of the nanotube can occur if the magnetic field $H$\nexceeds a dissipation-dependent critical value $H_{c}$, which we find to be of\nthe order of 10-100 mT for realistic parameters. The instability develops into\na stationary regime characterized by time periodic oscillations in the\nfundamental bending mode amplitude. We find that for nanotubes with large\nquality factors and a magnetic-field strength just above $H_{c}$ the frequency\nof the stationary vibrations is very close to the eigenfrequency of the\nfundamental mode. We also demonstrate that the magnetic field dependence of the\ntime averaged voltage drop across the nanotube has a singularity at $H=H_{c}$.\nWe discuss the possibility of using this phenomenon for the detection of\nnanotube vibrations.",
        "positive": "A primordial theory: We review the twistor approach to the Zhang-Hu theory of the four-dimensional\nQuantum Hall effect. We point out the key role played by the group Spin(4,4),\nas the symmetry group of the boundary. It is argued that this group, which\nignores the square root of minus one used in relativity and quantum mechanics,\nis the focal point of a primordial theory, one where the Cartan concept of\ntriality is paramount, from which the standard theories emerge via a series of\nphase transitions of the Zhang-Hu fluid. An important role will be played by\nthe Jordan cross-product algebras, particularly the exceptional Jordan algebra\nassociated to the split octaves and by the associated Freudenthal phase space.\nThe geometry and Hamiltonian theory of these spaces is examined in detail. A\npossible link to the theory of massive particles is outlined."
    },
    {
        "anchor": "Intrinsic spin orbit torque in a single domain nanomagnet: We present theoretical studies of the intrinsic spin orbit torque (SOT) in a\nsingle domain ferromagnetic layer with Rashba spin-orbit coupling (SOC) using\nthe non-equilibrium Green's function formalism for a model Hamiltonian. We find\nthat, to the first order in SOC, the intrinsic SOT has only the field-like\ntorque symmetry and can be interpreted as the longitudinal spin current induced\nby the charge current and Rashba field. We analyze the results in terms of the\nmaterial related parameters of the electronic structure, such as band filling,\nband width, exchange splitting, as well as the Rashba SOC strength. On the\nbasis of these numerical and analytical results, we discuss the magnitude and\nsign of SOT. Our results show that the different sign of SOT in identical\nferromagnetic layers with different supporting layers, e.g. Co/Pt and Co/Ta,\ncould be attributed to electrostatic doping of the ferromagnetic layer by the\nsupport.",
        "positive": "A theory for magnetic-field effects of nonmagnetic organic\n  semiconducting materials (Revised): A universal mechanism for strong magnetic-field effects of nonmagnetic\norganic semiconductors is presented. A weak magnetic field (less than hundreds\nmT) can substantially change the charge carrier hopping coefficient between two\nneighboring organic molecules when the two hopping states are not too\nsymmetric. Under the illumination of lights or under a high electric field, the\nchange of hopping coefficients leads also to the change of polaron density so\nthat photocurrent, photoluminescence, electroluminescence, magnetoresistance\nand electrical-injection current become sensitive to a weak magnetic field. The\npresent theory can not only explain all observed features, but also provide a\nsolid theoretical basis for the widely used empirical fitting formulas."
    },
    {
        "anchor": "Predicting the chemical stability of monatomic chains: A simple model for evaluating the thermal atomic transfer rates in\nnanosystems [EPL 94, 40002 (2011)] was developed to predict the chemical\nreaction rates of nanosystems with small gas molecules. The accuracy of the\nmodel was verified by MD simulations for molecular adsorption and desorption on\na monatomic chain. By the prediction, a monatomic carbon chain should survive\nfor 120 years in the ambient of 1 atm O2 at room temperature, and it is very\ninvulnerable to N2, H2O, NO2, CO and CO2, while a monatomic gold chain quickly\nruptures in vacuum. It is worth noting that since the model can be easily\napplied via common ab initio calculations, it could be widely used in the\nprediction of chemical stability of nanosystems.",
        "positive": "Semiclassical Mechanism for the Quantum Decay in Open Chaotic Systems: We address the decay in open chaotic quantum systems and calculate\nsemiclassical corrections to the classical exponential decay. We confirm random\nmatrix predictions and, going beyond, calculate Ehrenfest time effects. To\nsupport our results we perform extensive numerical simulations. Within our\napproach we show that certain (previously unnoticed) pairs of interfering,\ncorrelated classical trajectories are of vital importance. They also provide\nthe dynamical mechanism for related phenomena such as photo-ionization and\n-dissociation, for which we compute cross section correlations. Moreover, these\norbits allow us to establish a semiclassical version of the continuity\nequation."
    },
    {
        "anchor": "The Quantum Pinch Effect in Semiconducting Quantum Wires: A Bird's-Eye\n  View: Those who measure success with culmination do not seem to be aware that life\nis a journey not a destination. This spirit is best reflected in the unceasing\nfailures in efforts for solving the problem of controlled thermonuclear fusion\nfor even the simplest pinches for over decades; and the nature keeps us\nchallenging with examples. However, these efforts have permitted researchers\nthe obtention of a dense plasma with a lifetime that, albeit short, is\nsufficient to study the physics of the pinch effect, to create methods of\nplasma diagnostics, and to develop a modern theory of plasma processes. Most\nimportantly, they have impregnated the solid state plasmas, particularly the\nelectron-hole plasmas in semiconductors, which do not suffer from the issues\nrelated with the confinement and which have demonstrated their potential not\nonly for the fundamental physics but also for the device physics. Here, we\nreport on a two-component, cylindrical, quasi-one-dimensional quantum plasma\nsubjected to a {\\em radial} confining harmonic potential and an applied\nmagnetic field in the symmetric gauge. It is demonstrated that such a system as\ncan be realized in semiconducting quantum wires offers an excellent medium for\nobserving the quantum pinch effect at low temperatures. An exact analytical\nsolution of the problem allows us to make significant observations:\nsurprisingly, in contrast to the classical pinch effect, the particle density\nas well as the current density display a {\\em determinable} maximum before\nattaining a minimum at the surface of the quantum wire. The effect will persist\nas long as the equilibrium pair density is sustained. Therefore, the\ntechnological promise that emerges is the route to the precise electronic\ndevices that will control the particle beams at the nanoscale.",
        "positive": "Influence of a single defect on the conductance of a tunnel point\n  contact between a normal metal and a superconductor: We have investigated theoretically the conductance of a Normal-Superconductor\npoint-contact in the tunnel limit and analyzed the quantum interference effects\noriginating from the scattering of quasiparticles by point-like defects.\nAnalytical expressions for the oscillatory dependence of the conductance on the\nposition of the defect are obtained for the defect situated either in the\nnormal metal, or in the superconductor. It is found that the amplitude of\noscillations significantly increases when the applied bias approaches the gap\nenergy of the superconductor. The spatial distribution of the order parameter\nnear the surface in the presence of a defect is also obtained."
    },
    {
        "anchor": "Floquet dynamics in two-dimensional semi-Dirac semimetals and\n  three-dimensional Dirac semimetals: We study the photoresponse of two-dimensional semi-Dirac semimetals and\nthree-dimensional Dirac semimetals to off-resonant circularly polarized light.\nFor two-dimensional semi-Dirac semimetals we find that incident light does not\nopen a gap in the spectrum, in contrast to the case of purely linear\ndispersion. For the three-dimensional case we find that applying a circularly\npolarized light, one can tune from a trivial insulator to three-dimensional\nDirac semimetal with an inverted gap. We propose and show that application of\nlight leads to an intriguing platform for generation, motion and merging of\nthree-dimensional Dirac points.",
        "positive": "Conduction Channels of One-Atom Zinc Contacts: We have determined the transmission coefficients of atomic-sized Zn contacts\nusing a new type of breakjunction which contains a whisker as a central bridge.\nWe find that in the last conductance plateau the transport is unexpectedly\ndominated by a well-transmitting single conduction channel. We explain the\nexperimental findings with the help of a tight-binding model which shows that\nin an one-atom Zn contact the current proceeds through the 4s and 4p orbitals\nof the central atom."
    },
    {
        "anchor": "Effect of the interface resistance in non-local Hanle measurements: We use lateral spin valves with varying interface resistance to measure\nnon-local Hanle effect in order to extract the spin-diffusion length of the\nnon-magnetic channel. A general expression that describes spin injection and\ntransport, taking into account the influence of the interface resistance, is\nused to fit our results. Whereas the fitted spin-diffusion length value is in\nagreement with the one obtained from standard non-local measurements in the\ncase of a finite interface resistance, in the case of transparent contacts a\nclear disagreement is observed. The use of a corrected expression, recently\nproposed to account for the anisotropy of the spin absorption at the\nferromagnetic electrodes, still yields a deviation of the fitted spin-diffusion\nlength which increases for shorter channel distances. This deviation shows how\nsensitive the non-local Hanle fittings are, evidencing the complexity of\nobtaining spin transport information from such type of measurements.",
        "positive": "PT Symmetric Floquet Topological Phase: In this paper, we study the existence of Floquet topological insulators for\nPT symmetric non-Hermitian Hamiltonians. We consider an array of waveguide in\n1D with periodically changing non-Hermitian potential and predict the existence\nof Floquet topological insulators in the system. We also extend the concept of\nFloquet topological phase to a two dimensional non-Hermitian system."
    },
    {
        "anchor": "Observation of exchange Coulomb interactions in the quantum Hall state\n  at nu=3: Coulomb exchange interactions of electrons in the nu=3 quantum Hall state are\ndetermined from two inter-Landau level spin-flip excitations measured by\nresonant inelastic light scattering. The two coupled collective excitations are\nlinked to inter-Landau level spin-flip transitions arising from the N=0 and N=1\nLandau levels. The strong repulsion between the two spin-flip modes in the\nlong-wave limit is clearly manifested in spectra displaying Coulomb exchange\ncontributions that are comparable to the exchange energy for the quantum Hall\nstate at nu=1. Theoretical calculations within the Hartree-Fock approximation\nare in a good agreement with measured energies of spin-flip collective\nexcitations.",
        "positive": "Number Parity effect in the normal state of $SrTiO_3$: We study the recently discovered even-odd effects in the normal state of\nsingle-electron devices manufactured at strontium titanium oxide/lanthanum\naluminum oxide interfaces (STO/LAO). Within the framework of the number\nparity-projected formalism and a phenomenological fermion-boson model we find\nthat, in sharp contrast to conventional superconductors, the crossover\ntemperature $T^*$ for the onset of number parity effect is considerably larger\nthan the superconducting transition temperature $T_c$ due to the existence of a\npairing gap above $T_c$. Furthermore, the finite lifetime of the preformed\npairs reduces by several orders of magnitude the effective number of states\n$N_{\\rm eff}$ available for the unpaired quasiparticle in the odd parity state\nof the Coulomb blockaded STO/LAO island. Our findings are in qualitative\nagreement with the experimental results reported by Levy and coworkers for\nSTO/LAO based single electron devices."
    },
    {
        "anchor": "A Typology for Quantum Hall Liquids: There is a close analogy between the response of a quantum Hall liquid (QHL)\nto a small change in the electron density and the response of a superconductor\nto an externally applied magnetic flux - an analogy which is made concrete in\nthe Chern-Simons Landau-Ginzburg (CSLG) formulation of the problem. As the\nTypes of superconductor are distinguished by this response, so too for QHLs: a\ntypology can be introduced which is, however, richer than that in\nsuperconductors owing to the lack of any time-reversal symmetry relating\npositive and negative fluxes. At the boundary between Type I and Type II\nbehavior, the CSLG action has a \"Bogomol'nyi point,\" where the quasi-holes\n(vortices) are non-interacting - at the microscopic level, this corresponds to\nthe behavior of systems governed by a set of model Hamiltonians which have been\nconstructed to render exact a large class of QHL wavefunctions. All Types of\nQHLs are capable of giving rise to quantized Hall plateaux.",
        "positive": "Valley- and spin-filter in monolayer MoS$_2$: We propose a valley- and spin-filter based on a normal/ferromagnetic/normal\nmolybdenum disulfide (MoS$_2$) junction where the polarizations of the valley\nand the spin can be inverted by reversing the direction of the exchange field\nin the ferromagnetic region. By using a modified Dirac Hamiltonian and the\nscattering formalism, we find that the polarizations can be tuned by applying a\ngate voltage and changing the exchange field in the structure. We further\ndemonstrate that the presence of a topological term ($\\beta$) in the\nHamiltonian results in an enhancement or a reduction of the charge conductance\ndepending on the value of the exchange field."
    },
    {
        "anchor": "Magneto-anisotropic weak antilocalization in near-surface quantum wells: We investigate the effects of an in-plane magnetic field on the weak\nantilocalization signature of near-surface quantum wells lacking bulk and\ninversion symmetry. The measured magnetoconductivity exhibits a strong\nanisotropy with respect to the direction of the in-plane magnetic field. The\ntwo-fold symmetry of the observed magneto-anisotropy originates from the\ncompetition between Rashba and Dresselhaus spin-orbit couplings. The high\nsensitivity of the weak antilocalization to the spin texture produced by the\ncombined Zeeman and spin-orbit fields results in very large anisotropy ratios,\nreaching 100%. Using a semiclassical universal model in quantitative agreement\nwith the experimental data, we uniquely determine the values of the Dresselhaus\nand Rashba parameters as well as the effective in-plane g-factor of the\nelectrons. Understanding these parameters provides new prospects for novel\napplications ranging from spintronics to topological quantum computing.",
        "positive": "Spin-transfer Antiferromagnetic Resonance: Currents can induce spin excitations in antiferromagnets, even when they are\ninsulating. We investigate how spin transfer can cause antiferromagnetic\nresonance in bilayers and trilayers that consist of one antiferromagnetic\ninsulator and one or two metals. An ac voltage applied to the metal generates a\nspin Hall current that drives the magnetic moments in the antiferromagnet. We\nconsider excitation of the macrospin mode and of transverse standing-spin-wave\nmodes. By solving the Landau-Lifshitz-Gilbert equation in the antiferromagnetic\ninsulator and the spin-diffusion equation in the normal metal, we derive\nanalytical expressions for the spin-Hall-magnetoresistance and spin-pumping\ninverse-spin-Hall dc voltages. In bilayers, the two contributions compensate\neach other and cannot easily be distinguished. We present numerical results for\na MnF$_2|$Pt bilayer. Trilayers facilitate separation of the\nspin-Hall-magnetoresistance and spin-pumping voltages, thereby revealing more\ninformation about the spin excitations. We also compute the decay of the pumped\nspin current through the antiferromagnetic layer as a function of frequency and\nthe thickness of the antiferromagnetic layer."
    },
    {
        "anchor": "Thermoelectric signature of individual skyrmions: We experimentally study the thermoelectrical signature of individual\nskyrmions in chiral Pt/Co/Ru multilayers. Using a combination of controlled\nnucleation, single skyrmion annihilation, and magnetic field dependent\nmeasurements the thermoelectric signature of individual skyrmions is\ncharacterized. The observed signature is explained by the anomalous Nernst\neffect of the skyrmions spin structure. Possible topological contributions to\nthe observed thermoelectrical signature are discussed. Such thermoelectrical\ncharacterization allows for non-invasive detection and counting of skyrmions\nand enables fundamental studies of topological thermoelectric effects on the\nnano scale",
        "positive": "Room temperature optical manipulation of nuclear spin polarization in\n  GaAsN: The effect of hyperfine interaction on the room-temperature defect-enabled\nspin filtering effect in GaNAs alloys is investigated both experimentally and\ntheoretically through a master equation approach based on the hyperfine and\nZeeman interaction between electron and nuclear spin of the spin filtering\ndefect. We show that the nuclear spin polarization can be tuned through the\noptically induced spin polarization of conduction band electrons."
    },
    {
        "anchor": "Controllable giant magneto resistance and perfect spin filtering in\n  $\u03b1^{\\prime}$-borophene nanoribbons: By using non-equilibrium Green's function (NEGF) method and tight-binding\n(TB) approximation, we investigated a perfect control on spin transport in a\nzigzag $\\alpha^{\\prime}$-boron nanoribbon ($\\alpha^{\\prime}$-BNR) as the must\nsemi-conducting structure of borophene. It has been found that when an\n$\\alpha^{\\prime}$-BNR is exposed to an out-of-plane exchange magnetic field,\nspin splitting occurs for both spin-up and spin-down states in specific ranges\nof energy. Therefore, the spin polarization of current could be controlled by\nadjusting the energy of incoming electrons by means of an external back-gate\nvoltage. We focus on the edge manipulation of $\\alpha^{\\prime}$-BNR by\nferro-magnetic (FM) or anti-ferromagnetic (AFM) exchange field which leads to\nthe emergence of a giant magneto resistance and a perfect spin filtering. Local\ncurrent provides the best picture of spin distribution of current in the\nnanoribbon. In order to observe the response of the system to the proximity\neffect of magnetic strips, we calculate the magnetic moment of each site. Then,\nwe show that applying a transverse or perpendicular electric field in the\npresence of the exchange magnetic field gives another controlling tool on the\nspin polarization of current in a constant energy. Finally, by simultaneous\neffect of in-plane and out-of-plane exchange magnetic field on the edges of\nnanoribbon, we reach a control on spin rotation in the scattering region. Our\ninvestigation guarantees the $\\alpha^{\\prime}$-BNR as a promising two\ndimensional (2D) structure for spintronic purposes.",
        "positive": "Magnetoresistance of individual ferromagnetic GaAs/(Ga,Mn)As core-shell\n  nanowires: We investigate, angle dependent, the magnetoresistance (MR) of individual\nself-assembled ferromagnetic GaAs/(Ga,Mn)As core-shell nanowires at cryogenic\ntemperatures. The shape of the MR traces and the observed strong anisotropies\nin transport can be ascribed to the interplay of the negative magnetoresistance\neffect and a strong uniaxial anisotropy with the magnetic easy direction\npointing along the wire axis. The magnetoresistance can be well described by a\nquantitative analysis based on the concept of the effective magnetic field,\nusually used to describe ferromagnetic resonance phenomena. The nanowires we\ninvestigate exhibit a uniaxial anisotropy which is approximately 5 times larger\nthan the strain induced anisotropy observed in lithographically prepared\n(Ga,Mn)As stripes."
    },
    {
        "anchor": "Indirect excitons in a potential energy landscape created by a\n  perforated electrode: We report on the principle and realization of an excitonic device: a ramp\nthat directs the transport of indirect excitons down a potential energy\ngradient created by a perforated electrode at constant voltage. The device\nprovides an experimental proof of principle for controlling exciton transport\nwith electrode density gradients. We observed that the exciton transport\ndistance along the ramp increases with increasing exciton density. This effect\nis explained in terms of disorder screening by repulsive exciton-exciton\ninteractions.",
        "positive": "Interference and Interaction in Multiwall Carbon Nanotubes: We report equilibrium electric resistance R and tunneling spectroscopy dI/dV\nmeasurements obtained on single multiwall nanotubes contacted by four metallic\nAu fingers from above. At low temperature quantum interference phenomena\ndominate the magnetoresistance. The phase-coherence and elastic-scattering\nlengths are deduced. Because the latter is of order of the circumference of the\nnanotubes, transport is quasi-ballistic. This result is supported by a dI/dV\nspectrum which is in good agreement with the density-of-states (DOS) due to the\none-dimensional subbands expected for a perfect single-wall tube. As a function\nof temperature T the resistance increases on decreasing T and saturates at\napprox. 1-10 K for all measured nanotubes. R(T) cannot be related to the\nenergy-dependent DOS of graphene but is mainly caused by interaction and\ninterference effects. On a relatively small voltage scale of order 10 meV, a\npseudogap is observed in dI/dV which agrees with Luttinger-Liquid theories for\nnanotubes. Because we have used quantum diffusion based on Fermi-Liquid as well\nas Luttinger-Liquid theory in trying to understand our results, a large\nfraction of this paper is devoted to a careful discussion of all our results."
    },
    {
        "anchor": "Effects of voltage fluctuations on the current correlations in\n  mesoscopic Y-shaped conductors: We study current fluctuations in a phase coherent Y-shaped conductor\nconnected to external leads and voltage probes. The voltage probes are taken to\nhave finite impedances and thus can cause voltage fluctuations in the circuit.\nApplying the Keldysh formulation and a saddle point approximation appropriate\nfor slow fluctuations, we examine at zero temperature the feedback effects on\nthe current fluctuations due to the fluctuating voltages. We consider\nmesoscopic Y-shaped conductors made of tunnel junctions and of diffusive wires.\nUnlike two-terminal conductors, we find that for the Y-shaped conductors the\ncurrent moments in the presence of external impedances cannot be obtained from\nsimple rescaling of the bare moments already in the second moments. As a direct\nconsequence, we find that the cross correlation between the output terminals\ncan become positive due to the impedances in the circuit. We provide formulas\nfor the range of parameters that can cause positive cross correlations.",
        "positive": "Carbon nanotube quantum pumps: Recently nanomechanical devices composed of a long stationary inner carbon\nnanotube and a shorter, slowly-rotating outer tube have been fabricated. In\nthis Letter, we study the possibility of using such devices as adiabatic\nquantum pumps. Using the Brouwer formula, we employ a Green's function\ntechnique to determine the pumped charge from one end of the inner tube to the\nother, driven by the rotation of a chiral outer nanotube. We show that there is\nvirtually no pumping if the chiral angle of the two nanotubes is the same, but\nfor optimal chiralities the pumped charge can be a significant fraction of a\ntheoretical upper bound."
    },
    {
        "anchor": "Shot noise of quantum ring excitons in a planar microcavity: Shot noise of quantum ring (QR) excitons in a p-i-n junction surrounded by a\nmicrocavity is investigated theoretically. Some radiative decay properties of a\nQR exciton in a microcavity can be obtained from the observation of the current\nnoise, which also gives the extra information about one of the tunnel barriers.\nDifferent noise feature between the quantum dot (QD) and QR is pointed out, and\nmay be observed in a suitably designed experiment.",
        "positive": "Microscopic Theory of Polariton Lasing via Vibronically Assisted\n  Scattering: Polariton lasing has recently been observed in strongly coupled crystalline\nanthracene microcavities. A simple model is developed describing the onset of\nthe non-linear threshold based on a master equation including the relevant\nrelaxation processes and employing realistic material parameters. The mechanism\ngoverning the build-up of the polariton population - namely bosonic stimulated\nscattering from the exciton reservoir via a vibronically assisted process - is\ncharacterized and its efficiency calculated on the basis of a microscopic\ntheory. The role of polariton-polariton bimolecular quenching is identified and\ntemperature dependent effects are discussed."
    },
    {
        "anchor": "Conductance and noise signatures of Majorana backscattering: We propose a conductance measurement to detect the backscattering of chiral\nMajorana edge states. Because normal and Andreev processes have equal\nprobability for backscattering of a single chiral Majorana edge state, there is\nqualitative difference from backscattering of a chiral Dirac edge state, giving\nrise to half-integer Hall conductivity and decoupling of fluctuation in\nincoming and outgoing modes. The latter can be detected through thermal noise\nmeasurement. These experimental signatures of Majorana fermions are robust at\nfinite temperature and do not require the size of the backscattering region to\nbe mesoscopic.",
        "positive": "Electrical Control of Dynamic Spin Splitting Induced by Exchange\n  Interaction as Revealed by Time Resolved Kerr Rotation in a Degenerate\n  Spin-Polarized Electron Gas: The manipulation of spin degree of freedom have been demonstrated in spin\npolarized electron plasma in a heterostructure by using exchange-interaction\ninduced dynamic spin splitting rather than the Rashba and Dresselhaus types, as\nrevealed by time resolved Kerr rotation. The measured spin splitting increases\nfrom 0.256meV to 0.559meV as the bias varies from -0.3V to -0.6V. Both the sign\nswitch of Kerr signal and the phase reversal of Larmor precessions have been\nobserved with biases, which all fit into the framework of\nexchange-interaction-induced spin splitting. The electrical control of it may\nprovide a new effective scheme for manipulating spin-selected transport in spin\nFET-like devices."
    },
    {
        "anchor": "An Extended Huckel Theory based Atomistic Model for Graphene\n  Nanoelectronics: An atomistic model based on the spin-restricted extended Huckel theory (EHT)\nis presented for simulating electronic structure and I-V characteristics of\ngraphene devices. The model is applied to zigzag and armchair graphene\nnano-ribbons (GNR) with and without hydrogen passivation, as well as for\nbilayer graphene. Further calculations are presented for electric fields in the\nnano-ribbon width direction and in the bilayer direction to show electronic\nstructure modification. Finally, the EHT Hamiltonian and NEGF (Nonequilibrium\nGreen's function) formalism are used for a paramagnetic zigzag GNR to show\n2e2/h quantum conductance.",
        "positive": "Inter-Layer Screening Length to Electric Field in Thin Graphite Film: Electric conduction in thin graphite film was tuned by two gate electrodes to\nclarify how the gate electric field induces electric carriers in thin graphite.\nThe graphite was sandwiched between two gate electrodes arranged in a top and\nbottom gate configuration. A scan of the top gate voltage generates a\nresistance peak in ambiploar response. The ambipolar peak is shifted by the\nbottom gate voltage, where the shift rate depends on the graphite thickness.\nThe thickness-dependent peak shift was clarified in terms of the inter-layer\nscreening length to the electric field in the double-gated graphite film. The\nscreening length of 1.2 nm was experimentally obtained."
    },
    {
        "anchor": "Enhanced Logic Performance with Semiconducting Bilayer Graphene Channels: Realization of logic circuits in graphene with an energy gap (EG) remains one\nof the main challenges for graphene electronics. We found that large transport\nEGs (>100 meV) can be fulfilled in dual-gated bilayer graphene underneath a\nsimple alumina passivation top gate stack, which directly contacts the graphene\nchannels without an inserted buffer layer. With the presence of EGs, the\nelectrical properties of the graphene transistors are significantly enhanced,\nas manifested by enhanced on/off current ratio, subthreshold slope and current\nsaturation. For the first time, complementary-like semiconducting logic\ngraphene inverters are demonstrated that show a large improvement over their\nmetallic counterparts. This result may open the way for logic applications of\ngap-engineered graphene.",
        "positive": "Back-action noise in strongly interacting systems: the dc SQUID and the\n  interacting quantum point-contact: We study the back-action noise and measurement efficiency (i.e. noise\ntemperature) of a dc SQUID amplifier, and equivalently, a quantum point contact\ndetector formed in a Luttinger liquid. Using a mapping to a dissipative\ntight-binding model, we show that these systems are able to reach the quantum\nlimit even in regimes where several independent transport processes contribute\nto the current. We suggest how this is related to the underlying integrability\nof these systems."
    },
    {
        "anchor": "Electron spin resonance and collective excitations in magic-angle\n  twisted bilayer graphene: In a strongly correlated system, collective excitations contain key\ninformation regarding the electronic order of the underlying ground state. An\nabundance of collective modes in the spin and valley isospin channels of\nmagic-angle graphene moir\\'e bands has been alluded to by a series of recent\nexperiments. However, direct observation of collective excitations has remained\nelusive due to the lack of a spin probe. In this work, we use a\nresistively-detected electron spin resonance technique to look for low-energy\ncollective excitations in magic-angle twisted bilayer graphene. We report\ndirect observation of collective modes in the form of microwave-induced\nresonance near half filling of the moir\\'e flatbands. The frequency-magnetic\nfield dependence of these resonance modes sheds light onto the nature of\nintervalley spin coupling, allowing us to extract parameters such as\nintervalley exchange interaction and spin stiffness. Two independent\nobservations testify that the generation and detection of the microwave\nresonance relies on the strong correlation within the flat moir\\'e energy band.\nFirst, the onset of robust resonance response coincides with the spontaneous\nflavor polarization at half moir\\'e filling, and remains absent in the density\nrange where the underlying Fermi surface is isospin unpolarized. Second, we\nperformed the same resonance measurement on graphene monolayer and bilayer\nsamples, including twisted bilayer with a large twist angle, where flatband\nphysics is absent. We observe no indication of resonance response in these\nsamples across a large range of carrier density, microwave frequency and power.\nA natural explanation is that the resonance response near the magic angle\noriginates from \"Dirac revivals\" and the resulting isospin order.",
        "positive": "Orbital effect on the in-plane critical field in free-standing\n  superconducting nanofilms: The superconductor to normal metal phase transition induced by the in-plane\nmagnetic field is studied in free-standing Pb(111) nanofilms. In the considered\nstructures the energy quantization induced by the confinement leads to the\nthickness-dependent oscillations of the critical field (the so-called 'shape\nresonances'). In this paper we examine the influence of the orbital effect on\nthe in-plane critical magnetic field in nanofilms. We demonstrate that the\norbital term suppresses the critical field and reduces the amplitude of the\nthickness-dependent critical field oscillations. Moreover, due to the orbital\neffect, the slope $H_{c,||}-T_c$ at $T_c(0)$ becomes finite and decreases with\nincreasing film thickness in agreement with recent experiments. The temperature\n$t^*$ at which the superconductor to normal metal phase transition becomes of\nthe first order is also analyzed."
    },
    {
        "anchor": "Hard gap in epitaxial semiconductor-superconductor nanowires: Many present and future applications of superconductivity would benefit from\nelectrostatic control of carrier density and tunneling rates, the hallmark of\nsemiconductor devices. One particularly exciting application is the realization\nof topological superconductivity as a basis for quantum information processing.\nProposals in this direction based on proximity effect in semiconductor\nnanowires are appealing because the key ingredients are currently in hand.\nHowever, previous instances of proximitized semiconductors show significant\ntunneling conductance below the superconducting gap, suggesting a continuum of\nsubgap states---a situation that nullifies topological protection. Here, we\nreport a hard superconducting gap induced by proximity effect in a\nsemiconductor, using epitaxial Al-InAs superconductor-semiconductor nanowires.\nThe hard gap, along with favorable material properties and gate-tunability,\nmakes this new hybrid system attractive for a number of applications, as well\nas fundamental studies of mesoscopic superconductivity.",
        "positive": "Chiral coupling between a ferromagnetic magnon and a superconducting\n  qubit: Chiral coupling at the single-quantum level promises to be a remarkable\npotential for quantum information processing. Here we propose to achieve a\nchiral interaction between a magnon mode in a ferromagnetic sphere and a\nsuperconducting qubit mediated by a one-dimensional coupled-cavity array. When\nthe qubit is coupled to two lattice sites of the array and each one is encoded\nwith a tunable phase, we can acquire a directional qubit-magnon interaction via\nthe quantum interference effect. This work opens up a new route to construct\nchiral devices, which are expected to become a building block in quantum\nmagnonic networks."
    },
    {
        "anchor": "On the Instabilities of the Walker Propagating Domain Wall Solution: A powerful mathematical method for front instability analysis that was\nrecently developed in the field of nonlinear dynamics is applied to the 1+1\n(spatial and time) dimensional Landau-Lifshitz-Gilbert (LLG) equation. From the\nessential spectrum of the LLG equation, it is shown that the famous Walker\nrigid body propagating domain wall (DW) is not stable against the spin wave\nemission. In the low field region only stern spin waves are emitted while both\nstern and bow waves are generated under high fields. By using the properties of\nthe absolute spectrum of the LLG equation, it is concluded that in a high\nenough field, but below the Walker breakdown field, the Walker solution could\nbe convective/absolute unstable if the transverse magnetic anisotropy is larger\nthan a critical value, corresponding to a significant modification of the DW\nprofile and DW propagating speed. Since the Walker solution of 1+1 dimensional\nLLG equation can be realized in experiments, our results could be also used to\ntest the mathematical method in a controlled manner.",
        "positive": "Improving mobility of silicon metal-oxide-semiconductor devices for\n  quantum dots by high vacuum activation annealing: To improve mobility of fabricated silicon metal-oxide-semiconductor (MOS)\nquantum devices, forming gas annealing is a common method used to mitigate the\neffects of disorder at the Si/SiO2 interface. However, the importance of\nactivation annealing is usually ignored. Here, we show that a high vacuum\nenvironment for implantation activation is beneficial for improving mobility\ncompared to nitrogen atmosphere. Low-temperature transport measurements of Hall\nbars show that peak mobility can be improved by a factor of two, reaching 1.5\nm^2/(Vs) using high vacuum annealing during implantation activation. Moreover,\nthe charge stability diagram of a single quantum dot is mapped, with no visible\ndisturbance caused by disorder, suggesting possibility of fabricating\nhigh-quality quantum dots on commercial wafers. Our results may provide\nvaluable insights into device optimization in silicon-based quantum computing."
    },
    {
        "anchor": "Observation of topologically protected compact edge states in\n  flux-dressed graphene photonic lattices: Systems with engineered flatband spectra are a postulate of high-capacity\ntransmission links and a candidate for high-temperature superconductivity.\nHowever, their operation relies on the edge or surface modes susceptible to\nfluctuations and fabrication errors. While the mode robustness can be enhanced\nby a combination of Aharonov-Bohm caging and topological insulation, the design\nof the corresponding flatbands requires approaches beyond the standard\n$k$-vector-based methods. Here, we propose a synthetic-flux probe as a solution\nto this problem and a route to the realization of ultra-stable modes. We prove\nthe concept in a laser-fabricated graphene-like ribbon photonic lattice with\nthe band-flattening flux induced by \"P\" waveguide coupling. The topological\nnon-triviality is witnessed by an integer Zak phase derived from the mean\nchiral displacement. Mode stability is evidenced by excellent mode localization\nand the robustness to fabrication tolerances and variations of the input phase.\nOur results can serve as a basis for the development of multi-flat-band\nmaterials for low-energy electronics.",
        "positive": "A Study of Asymptotic Freedom like Behavior for Topological States of\n  Matter: We present results for asymptotic freedom like behavior for the topological\nstate of the helical spin liquid system with finite proximity induced\nsuperconducting gap. We derive two different quantum\nBerezinskii-Kosterlitz-Thouless (BKT) equations for the two different limit of\nthis model Hamiltonian. The common quantum phase for these two quantum BKT\ntransitions is the helical Luttinger liquid phase where there is no evidence of\nasymptotic freedom. There is no evidence of superconductor-insulator transition\nfor this asymptotic freedom study. We observe the evidance of asymptotic\nfreedom for the two model Hamiltonian, but the character of the asymptotic\nphases are different. We also observe that the Luttinger liquid parameter plays\na significant role to determine the asymptotic freedom but the chemical\npotential has no effect on it."
    },
    {
        "anchor": "Long hold times in a two-junction electron trap: The hold time $\\tau$ of a single-electron trap is shown to increase\nsignificantly due to suppression of environmentally assisted tunneling events.\nUsing two rf-tight radiation shields instead of a single one, we demonstrate\nincrease of $\\tau$ by a factor exceeding $10^3$, up to about 10 hours, for a\ntrap with only two superconductor (S) -- normal-metal (N) tunnel junctions and\nan on-chip resistor $R$ (R-SNS structure). In the normal state, the improved\nshielding made it possible to observe $\\tau\\sim$ 100 s, which is in reasonable\nagreement with the quantum-leakage-limited level expected for the two-electron\ncotunneling process.",
        "positive": "Parity-preserving and magnetic field resilient superconductivity in\n  indium antimonide nanowires with tin shells: We study bottom-up grown semiconductor indium antimonide nanowires that are\ncoated with shells of tin. The shells are uniform in thickness. The interface\nbetween Sn and InSb is abrupt and without interdiffusion. Devices for transport\nare prepared by in-situ shadowing of nanowires using nearby nanowires as well\nas flakes, resulting in etch-free junctions. Tin is found to induce a hard\nsuperconducting gap in the range 600-700 micro-eV. Superconductivity persists\nup to 4 T in magnetic field. A tin island exhibits the coveted two-electron\ncharging effect, a hallmark of charge parity stability. The findings open\navenues for superconducting and topological quantum circuits based on new\nsuperconductor-semiconductor combinations."
    },
    {
        "anchor": "2D Quantum Turbulence in Polariton Condensates: The coexistence of the energy and enstrophy cascades in 2D quantum turbulence\nis one of the important open questions in the studies of quantum fluids. Here,\nwe show that polariton condensates are particularly suitable for the possible\nobservation of scaling on sufficiently large scales. The shape of raw energy\nspectra depends on the procedure of condensate excitation (stirring), but the\nenergy spectra of clustered vortices always exhibit the -5/3 power law. In the\noptimal case, the cascade can be observed over almost 2 decades.",
        "positive": "High Kondo temperature (TK ~ 80 K) in self-assembled InAs quantum dots\n  laterally coupled to nanogap electrodes: We have fabricated single electron tunneling structures by forming nanogap\nmetallic electrodes directly upon single self-assembled InAs quantum dots\n(QDs). The fabricated samples exhibited clear Coulomb blockade effects.\nFurthermore, a clear Kondo effect was observed when strong coupling between the\nelectrodes and the QDs was realized using a large QD with a diameter of ~ 100\nnm. From the temperature dependence of the linear conductance at the Kondo\nvalley, the Kondo temperature TK was determined to be ~ 81 K. This is the\nhighest TK ever reported for artificial quantum nanostructures."
    },
    {
        "anchor": "Spin Seebeck effect and thermal spin galvanic effect in Ni80Fe20/p-Si\n  bilayers: The development of spintronics and spin-caloritronics devices need efficient\ngeneration, detection and manipulation of spin current. The thermal spin\ncurrent from spin-Seebeck effect has been reported to be more energy efficient\nthan the electrical spin injection methods. But, spin detection has been the\none of the bottlenecks since metals with large spin-orbit coupling is an\nessential requirement. In this work, we report an efficient thermal generation\nand interfacial detection of spin current. We measured a spin-Seebeck effect in\nNi80Fe20 (25 nm)/p-Si (50 nm) (polycrystalline) bilayers without heavy metal\nspin detector. The p-Si, having the centosymmetric crystal structure, has\ninsignificant intrinsic spin-orbit coupling leading to negligible spin-charge\nconversion. We report a giant inverse spin-Hall effect, essential for detection\nof spin-Seebeck effect, in the Ni80Fe20/p-Si bilayer structure, which\noriginates from Rashba spin orbit coupling due to structure inversion asymmetry\nat the interface. In addition, the thermal spin pumping in p-Si leads to spin\ncurrent from p-Si to Ni80Fe20 layer due to thermal spin galvanic effect and\nspin-Hall effect causing spin-orbit torques. The thermal spin-orbit torques\nleads to collapse of magnetic hysteresis of 25 nm thick Ni80Fe20 layer. The\nthermal spin-orbit torques can be used for efficient magnetic switching for\nmemory applications. These scientific breakthroughs may give impetus to the\nsilicon spintronics and spin-caloritronics devices.",
        "positive": "Interference in interacting quantum dots with spin: We study spectral and transport properties of interacting quantum dots with\nspin. Two particular model systems are investigated: Lateral multilevel and two\nparallel quantum dots. In both cases different paths through the system can\ngive rise to interference. We demonstrate that this strengthens the multilevel\nKondo effect for which a simple two-stage mechanism is proposed. In parallel\ndots we show under which conditions the peak of an interference-induced orbital\nKondo effect can be split."
    },
    {
        "anchor": "Squeezing of quantum noise of motion in a micromechanical resonator: A pair of conjugate observables, such as the quadrature amplitudes of\nharmonic motion, have fundamental fluctuations which are bound by the\nHeisenberg uncertainty relation. However, in a squeezed quantum state,\nfluctuations of a quantity can be reduced below the standard quantum limit, at\nthe cost of increased fluctuations of the conjugate variable. Here we prepare a\nnearly macroscopic moving body, realized as a micromechanical resonator, in a\nsqueezed quantum state. We obtain squeezing of one quadrature amplitude $1.1\n\\pm 0.4$ dB below the standard quantum limit, thus achieving a long-standing\ngoal of obtaining motional squeezing in a macroscopic object.",
        "positive": "Interplay of charge and heat transport in a nano-junction in the\n  out-of-equilibrium cotunneling regime: We study the charge transport and the heat transfer through a nano-junction\ncomposed of a small metallic grain weakly coupled to two metallic leads. We\nfocus on the cotunneling regime out-of-equilibrium, where the bias voltage and\nthe temperature gradient between the leads strongly drive electron and phonon\ndegrees of freedom in the grain that in turn have a strong feedback on the\ntransport through the grain. We derive and solve coupled kinetic equations for\nelectron and phonon degrees of freedom in the grain. We obtain the heat fluxes\nbetween cotunneling electrons, bosonic electron-hole excitations in the grain,\nand phonons, and self-consistently find the current-voltage characteristics. We\ndemonstrate that the transport in the nano-junction is very sensitive to the\nspectrum of the bosonic modes in the grain."
    },
    {
        "anchor": "A New Paradigm to Half-Metallicity in Graphene Nanoribbons: In contrast to the well recognized transverse-electric-field-induced\nhalf-metallicity in zigzag graphene nanoribbons, here we demonstrate by\nfirst-principles calculations that zigzag graphene nanoribbons sandwiched\nbetween hexagonal boron nitride nanoribbons or sheets can be tuned into\nhalf-metal simply by a bias voltage or a moderate compressive strain. The\nhalf-metallicity is attributed to an enhanced coupling effect of spontaneous\npolarization and asymmetrical exchange correlation along the ribbon width. The\nfindings should open a viable route for efficient spin-resolved band\nengineering in graphene based devices that are compatible with the current\ntechnology of semiconductor industry.",
        "positive": "Low-bias Negative Differential Resistance effect in armchair graphene\n  nanoribbon junctions: Graphene nanoribbons with armchair edges (AGNRs) have bandgaps that can be\nflexibly tuned via the ribbon width. A junction made of a narrower AGNR\nsandwiched between two wider AGNR leads was recently reported to possess two\nperfect transmission channels close to the Fermi level. Here, we report that by\nusing a bias voltage to drive these transmission channels into the gap of the\nwider AGNR lead, we can obtain a negative differential resistance (NDR) effect.\nOwing to the intrinsic properties of the AGNR junctions, the on-set bias\nreaches as low as ~ 0.2 V and the valley current almost vanishes. We further\nshow that such NDR effect is robust against details of the atomic structure of\nthe junction, substrate and whether the junction is made by etching or by\nhydrogenation."
    },
    {
        "anchor": "Visualization of superparamagnetic dynamics in magnetic topological\n  insulators: Quantized Hall conductance is a generic feature of two dimensional electronic\nsystems with broken time reversal symmetry. In the quantum anomalous Hall state\nrecently discovered in magnetic topological insulators, time reversal symmetry\nis believed to be broken by long-range ferromagnetic order, with quantized\nresistance observed even at zero external magnetic field. Here, we use scanning\nnanoSQUID magnetic imaging to provide a direct visualization of the dynamics of\nthe quantum phase transition between the two anomalous Hall plateaus in a\nCr-doped (Bi,Sb)$_2$Te$_3$ thin film. Contrary to naive expectations based upon\nmacroscopic magnetometry, our measurements reveal a superparamagnetic state\nformed by weakly interacting magnetic domains with a characteristic size of few\ntens of nanometers. The magnetic phase transition occurs through random\nreversals of these local moments, which drive the electronic Hall plateau\ntransition. Surprisingly, we find that the electronic system can in turn drive\nthe dynamics of the magnetic system, revealing a subtle interplay between the\ntwo coupled quantum phase transitions.",
        "positive": "Mesoscopic circuits with charge discreteness:quantum transmission lines: We propose a quantum Hamiltonian for a transmission line with charge\ndiscreteness. The periodic line is composed of an inductance and a capacitance\nper cell. In every cell the charge operator satisfies a nonlinear equation of\nmotion because of the discreteness of the charge. In the basis of one-energy\nper site, the spectrum can be calculated explicitly. We consider briefly the\nincorporation of electrical resistance in the line."
    },
    {
        "anchor": "Electronic, thermal, and optical properties of graphene like SiC$_x$\n  structures: Significant effects of Si atom configurations: We investigate the electronic, thermal, and optical characteristics of\ngraphene like SiC$_x$ structure using model calculations based on density\nfunctional theory. The change in the energy bandgap can be tuned by the Si\natomic configuration, rather than the dopants ratio. The effects of the\nconcentration of the Si atoms and the shape of supercell are kept constant, and\nonly the interaction effects of two Si atoms are studied by varying their\npositions. If the Si atoms are at the same sublattice positions, a maximum\nbandgap is obtained leading to an increased Seebeck coefficient and figure of\nmerit. A deviation in the Wiedemann-Franz ratio is also found, and a maximum\nvalue of the Lorenz number is thus discovered. Furthermore, a significant red\nshift of the first peak of the imaginary part of the dielectric function\ntowards the visible range of the electromagnetic radiation is observed. On the\nother hand, if the Si atoms are located at different sublattice positions, a\nsmall bandgap is seen because the symmetry of sublattice remains almost\nunchanged. Consequently, the Seebeck coefficient and the dielectric function\nare only slightly changed compared to pristine graphene. In addition, the\nelectron energy loss function is suppressed in Si-doped graphene. These unique\nvariations of the thermal and the optical properties of Si-doped graphene are\nof importance to understand experiments relevant to optoelectronic\napplications.",
        "positive": "Probing graphene \u03c7(2) using a gold photon sieve: Nonlinear second harmonic optical activity of graphene covering a gold photon\nsieve was determined for different polarizations. The photon sieve consists of\na subwavelength gold nanohole array placed on glass. It combines the benefits\nof efficient light trapping and surface plasmon propagation in order to unravel\ndifferent elements of graphene second-order susceptibility \\chi(2). Those\nelements efficiently contribute to second harmonic generation. In fact, the\ngraphene- coated photon sieve produces a second harmonic intensity at least two\norders of magnitude higher compared with a bare, flat gold layer and an order\nof magnitude coming from the plasmonic effect of the photon sieve; the\nremaining enhancement arises from the graphene layer itself. The measured\nsecond harmonic generation yield, supplemented by semianalytical computations,\nprovides an original method to constrain the graphene \\chi(2) elements. The\nvalues obtained are |d_{31} + d_{33}| < 8.1 x 10^3 pm^2/V and |d_{15}| < 1.4 x\n10^6 pm^2/V for a second harmonic signal at 780 nm. This original method can be\napplied to any kind of 2D materials covering such a plasmonic structure."
    },
    {
        "anchor": "Boosting current-induced molecular dynamics with machine-learning\n  potential: In a current-carrying single-molecular junction (SMJ), a hierarchy of hybrid\nenergy transport processes takes place under a highly nonequilibrium situation,\nincluding energy transfer from electrons to molecular vibrations via\nelectron-vibration interaction, energy redistribution within different\nvibrational modes via anharmonic coupling, and eventual energy transport to\nsurrounding electrodes. A comprehensive understanding of such processes is a\nprerequisite for their potential applications as single-molecular devices. $Ab$\n$initio$ current-induced molecular dynamics (MD) is an ideal approach to\naddress this complicated problem. But the computational cost hinders its usage\nin systematic study of realistic SMJs. Here, we achieve orders of magnitude\nimprovement in the speed of MD simulation by employing machine-learning\npotential with accuracy comparable to density functional theory. Using this\napproach, we show that SMJs with graphene electrodes generate order of\nmagnitude less heating than those with gold electrodes. Our work illustrates\nthe superior heat transport property of graphene as electrodes for SMJs, thanks\nto its better phonon spectral overlap with molecular vibrations.",
        "positive": "Circulating currents and magnetic moments in quantum rings: In circuits containing closed loops the operator for the current is\ndetermined by charge conservation up to an arbitrary divergenceless current. In\nthis work we propose a formula to calculate the magnetically active circulating\ncurrent $I_{\\rm ring}$ flowing along a quantum ring connected to biased leads.\nBy {\\em gedanken experiments} we argue that $I_{\\rm ring}$ can be obtained from\nthe response of the gran-canonical energy of the ring to an external magnetic\nflux. The results agree with those of the conventional approach in the case of\nisolated rings. However, for connected rings $I_{\\rm ring}$ cannot be obtained\nas a linear combination of bond currents."
    },
    {
        "anchor": "Time-Domain Spectroscopy of Mesoscopic Conductors Using Voltage Pulses: The development of single-electron sources has paved the way for a novel type\nof experiments in which individual electrons are emitted into a\nquantum-coherent circuit. In one approach, single-electron excitations are\ngenerated by applying Lorentzian-shaped voltage pulses to a contact. Here, we\npropose to use such voltage pulses for electronic spectroscopy of mesoscopic\ndevices. Specifically, we show how characteristic timescales of a\nquantum-coherent conductor can be extracted from the distribution of waiting\ntimes between charge pulses propagating through a mesoscopic circuit. To\nillustrate our idea, we employ Floquet scattering theory to evaluate the\nelectron waiting times for an electronic Fabry-P\\'erot cavity and a\nMach-Zehnder interferometer. We discuss the perspectives for an experimental\nrealization of our proposal and identify possible avenues for further\ndevelopments.",
        "positive": "Mapping the twist angle and unconventional Landau levels in magic angle\n  graphene: The emergence of flat electronic bands and of the recently discovered\nstrongly correlated and superconducting phases in twisted bilayer graphene\ncrucially depends on the interlayer twist angle upon approaching the magic\nangle $\\theta_M \\approx 1.1\\deg$. Although advanced fabrication methods allow\nalignment of graphene layers with global twist angle control of about\n0.1$\\deg$, little information is currently available on the distribution of the\nlocal twist angles in actual magic angle twisted bilayer graphene (MATBG)\ntransport devices. Here we map the local $\\theta$ variations in hBN\nencapsulated devices with relative precision better than 0.002$\\deg$ and\nspatial resolution of a few moir$\\'e$ periods. Utilizing a scanning\nnanoSQUID-on-tip, we attain tomographic imaging of the Landau levels in the\nquantum Hall state in MATBG, which provides a highly sensitive probe of the\ncharge disorder and of the local band structure determined by the local\n$\\theta$. We find that even state-of-the-art devices, exhibiting high-quality\nglobal MATBG features including superconductivity, display significant\nvariations in the local $\\theta$ with a span close to 0.1$\\deg$. Devices may\neven have substantial areas where no local MATBG behavior is detected, yet\nstill display global MATBG characteristics in transport, highlighting the\nimportance of percolation physics. The derived $\\theta$ maps reveal substantial\ngradients and a network of jumps. We show that the twist angle gradients\ngenerate large unscreened electric fields that drastically change the quantum\nHall state by forming edge states in the bulk of the sample, and may also\nsignificantly affect the phase diagram of correlated and superconducting\nstates. The findings call for exploration of band structure engineering\nutilizing twist-angle gradients and gate-tunable built-in planar electric\nfields for novel correlated phenomena and applications."
    },
    {
        "anchor": "Classification of crystalline topological insulators through K-theory: Topological phases for free fermions in systems with crystal symmetry are\nclassified by the topology of the valence band viewed as a vector bundle over\nthe Brillouin zone. Additional symmetries, such as crystal symmetries which act\nnon-trivially on the Brillouin zone, or time-reversal symmetry, endow the\nvector bundle with extra structure. These vector bundles are classified by a\nsuitable version of K-theory. While relatively easy to define, these K-theory\ngroups are notoriously hard to compute in explicit examples. In this paper we\ndescribe in detail how one can compute these K-theory groups starting with a\ndecomposition of the Brillouin zone in terms of simple submanifolds on which\nthe symmetries act nicely. The main mathematical tool is the Atiyah-Hirzebruch\nspectral sequence associated to such a decomposition, which will not only yield\nthe explicit result for several crystal symmetries, but also sheds light on the\norigin of the topological invariants. This extends results that have appeared\nin the literature so far. We also describe examples in which this approach\nfails to directly yield a conclusive answer, and discuss various open problems\nand directions for future research.",
        "positive": "Spin-current modulation and square-wave transmission through\n  periodically stubbed electron waveguides: Ballistic spin transport through waveguides, with symmetric or asymmetric\ndouble stubs attached to them periodically, is studied systematically in the\npresence of a weak spin-orbit coupling that makes the electrons precess. By an\nappropriate choice of the waveguide length and of the stub parameters injected\nspin-polarized electrons can be blocked completely and the transmission shows a\nperiodic and nearly square-type behavior, with values 1 and 0, with wide gaps\nwhen only one mode is allowed to propagate in the waveguide. A similar behavior\nis possible for a certain range of the stub parameters even when two-modes can\npropagate in the waveguide and the conductance is doubled. Such a structure is\na good candidate for establishing a realistic spin transistor. A further\nmodulation of the spin current can be achieved by inserting defects in a\nfinite-number stub superlattice. Finite-temperature effects on the spin\nconductance are also considered."
    },
    {
        "anchor": "Controlling spin polarization of a quantum dot via a helical edge state: We investigate a Zeeman-split quantum dot (QD) containing a single spin 1/2\nweakly coupled to a helical Luttinger liquid (HLL) within a generalized master\nequation approach. The HLL induces a tunable magnetization direction on the QD\ncontrolled by an applied bias voltage when the quantization axes of the QD and\nthe HLL are noncollinear. The backscattering conductance (BSC) in the HLL is\nfinite and shows a resonance feature when the bias voltage equals the Zeeman\nenergy in magnitude. The observed BSC asymmetry in bias voltage directly\nreflects the quantization axis of the HLL spin.",
        "positive": "Canted phase in double quantum dots: We perform a Hartree-Fock calculation in order to describe the ground state\nof a vertical double quantum dot in the absence of magnetic fields parallel to\nthe growth direction. Intra- and interdot exchange interactions determine the\nsinglet or triplet character of the system as the tunneling is tuned. At finite\nZeeman splittings due to in-plane magnetic fields, we observe the continuous\nquantum phase transition from ferromagnetic to symmetric phase through a canted\nantiferromagnetic state. The latter is obtained even at zero Zeeman energy for\nan odd electron number."
    },
    {
        "anchor": "Acoustically driven storage of light in a quantum well: The strong piezoelectric fields accompanying a surface acoustic wave on a\nsemiconductor quantum well structure are employed to dissociate optically\ngenerated excitons and efficiently trap the created electron hole pairs in the\nmoving lateral potential superlattice of the sound wave. The resulting spatial\nseparation of the photogenerated ambipolar charges leads to an increase of the\nradiative lifetime by orders of magnitude as compared to the unperturbed\nexcitons. External and deliberate screening of the lateral piezoelectric fields\ntriggers radiative recombination after very long storage times at a remote\nlocation on the sample.",
        "positive": "Anomalous conduction and second sound in the Fermi-Pasta-Ulam-Tsingou\n  chain: wave-turbulence approach: One-dimensional particle chains are fundamental models to explain anomalous\nthermal conduction in low-dimensional solids like nanotubes and nanowires. In\nthese systems the thermal energy is carried by phonons, i.e. propagating\nlattice oscillations that interact via nonlinear resonance. The average energy\ntransfer between the phonons is described by the wave kinetic equation (WKE),\nderived directly from the microscopic dynamics. Here, we use the spatially\nnonhomogeneous WKE of the prototypical $\\beta-$ Fermi-Pasta-Ulam-Tsingou (FPUT)\nmodel, equipped with thermostats able to set different temperatures at the two\nends. Our main findings are as follows: (i) The anomalous scaling of the\nconductivity with the system size, in close agreement with the known results\nfrom the microscopic dynamics, is due to a nontrivial interplay between high\nand low wavenumbers. (ii) The high-wavenumber phonons relax to local\nthermodynamic equilibrium transporting energy diffusively, {\\it \\`a la\nFourier}. (iii) The low-wavenumber phonons are nearly noninteracting and\ntransfer energy ballistically; this latter phenomenon is the analogous of the\nsecond sound emission, observed for example in superfluids."
    },
    {
        "anchor": "Spin interferometry with electrons in nanostructures: A road to\n  spintronic devices: The wave nature of electrons in semiconductor nanostructures results in\nspatial interference effects similar to those exhibited by coherent light. The\npresence of spin-orbit coupling renders interference in spin space and in real\nspace interdependent, making it possible to manipulate the electron's spin\nstate by addressing its orbital degree of freedom. This suggests the utility of\nelectronic analogs of optical interferometers as blueprints for new spintronics\ndevices. We demonstrate the usefulness of this concept using the Mach-Zehnder\ninterferometer as an example. Its spin-dependent analog realizes a\nspin-controlled field-effect transistor without magnetic contacts and may be\nused as a quantum logical gate.",
        "positive": "Magnetic-field-induced Stoner transition in a dilute quantum Hall system: In a recent paper [Phys.Rev.B.\\textbf{84}, 161307 (2011)], experimental data\non spin splitting in the integer quantum Hall effect has been reported in a\nhigh mobility dilute 2D electron gas with electron density as low as 0.2\n$\\times$ 10$^{11}$ cm $^{-2}$. In this work, we show that an excellent\n\\emph{quantitative} description of these data can be obtained within the model\nof the magnetic-field-induced Stoner transition in the quantum Hall regime.\nThis provides a powerful tool to probe the non-trivial density dependance of\nelectron-electron interactions in the dilute regime of the 2D electron gas."
    },
    {
        "anchor": "Euler characteristic number of the energy band and the reason for its\n  non-integer values: The topological Euler characteristic number of the energy band proposed in\nour previous work (see Yu-Quan Ma et al., arXiv:1202.2397; EPL 103, 10008\n(2013)) has been recently experimentally observed by X. Tan et al., Phys. Rev.\nLett. \\textbf{122}, 210401 (2019), in which a topological phase transition in a\ntime-reversal-symmetric system simulated by the superconducting circuits is\nwitnessed by the Euler number of the occupied band instead of the vanishing\nChern number. However, we note that there are some confusions about the\nnon-integer behaviors of the Euler number in the topological trivial phase. In\nthis paper, we show that the reason is straightforward because the quantum\nmetric tensor $g_{\\mu \\nu} $ is actually positive semi-definite. In a general\ntwo-dimensional two-band system, we can proved that: (1) If the phase is\ntopological trivial, then the quantum metric must be degenerate (singular)~---\n$\\det {g_{\\mu \\nu} }=0$ in some region of the first Brillouin zone. This leads\nto the invalidity of the Gauss-Bonnet formula and exhibits an ill-defined\n``non-integer Euler number''; (2) If the phase is topological nontrivial with a\nnon-vanishing Berry curvature, then the quantum metric will be a positive\ndefinite Riemann metric in the entire first Brillouin zone. Therefore the Euler\nnumber of the energy band will be guaranteed an even number $\\chi=2(1-g)$ by\nthe Gauss-Bonnet theorem on the closed two-dimensional Bloch energy band\nmanifold with the genus $g$, which provides an effective topological index for\na class of nontrivial topological phases.",
        "positive": "Hilbert space structure of the low energy sector of U(N) quantum Hall\n  ferromagnets and their classical limit: Using the Lieb-Mattis ordering theorem of electronic energy levels, we\nidentify the Hilbert space of the low energy sector of U($N$) quantum\nHall/Heisenberg ferromagnets at filling factor $M$ for $L$ Landau/lattice sites\nwith the carrier space of irreducible representations of U($N$) described by\nrectangular Young tableaux of $M$ rows and $L$ columns, and associated with\nGrassmannian phase spaces U($N$)/U($M$)$\\times$U($N-M$). We embed this\n$N$-component fermion mixture in Fock space through a Schwinger-Jordan (boson\nand fermion) representation of U($N$)-spin operators. We provide different\nrealizations of basis vectors using Young diagrams, Gelfand-Tsetlin patterns\nand Fock states (for an electron/flux occupation number in the\nfermionic/bosonic representation). U($N$)-spin operator matrix elements in the\nGelfand-Tsetlin basis are explicitly given. Coherent state excitations above\nthe ground state are computed and labeled by complex $(N-M)\\times M$ matrix\npoints $Z$ on the Grassmannian phase space. They adopt the form of a U($N$)\ndisplaced/rotated highest-weight vector, or a multinomial Bose-Einstein\ncondensate in the flux occupation number representation. Replacing U($N$)-spin\noperators by their expectation values in a Grassmannian coherent state allows\nfor a semi-classical treatment of the low energy (long wavelength)\nU($N$)-spin-wave coherent excitations (skyrmions) of U($N$) quantum Hall\nferromagnets in terms of Grasmannian nonlinear sigma models."
    },
    {
        "anchor": "Realization of a Hopf insulator in circuit systems: Three-dimensional (3D) two-band Hopf insulators are a paradigmatic example of\ntopological phases beyond the topological classifications based on powerful\nmethods like $K$-theory and symmetry indicators.Since this class of topological\ninsulating phases was theoretically proposed in 2008, they have attracted\nsignificant interest owing to their conceptual novelty, connection to knot\ntheory, and many fascinating physical properties. However, because their\nrealization requires special forms of long-range spin-orbit coupling (SOC),\nthey have not been achieved in any 3D system yet. Here we report the first\nexperimental realization of the long-sought-after Hopf insulator in a 3D\ncircuit system. To implement the Hopf insulator, we construct basic pseudo-spin\nmodules and connection modules that can realize $2\\times2$-matrix elements and\nthen design the circuit network according to a tight-binding Hopf insulator\nHamiltonian constructed by the Hopf map. By simulating the band structure of\nthe designed circuit network and calculating the Hopf invariant, we find that\nthe circuit realizes a Hopf insulator with Hopf invariant equaling $4$.\nExperimentally, we measure the band structure of a printed circuit board and\nfind the observed properties of the bulk bands and topological surface states\n(TSS) are in good agreement with the theoretical predictions, verifying the\nbulk-boundary correspondence of the Hopf insulator. Our scheme brings the\nexperimental study of Hopf insulators to reality and opens the door to the\nimplementation of more unexplored topological phases beyond the known\ntopological classifications.",
        "positive": "Fractionalizing Majorana fermions: non-abelian statistics on the edges\n  of abelian quantum Hall states: We study the non-abelian statistics characterizing systems where\ncounter-propagating gapless modes on the edges of fractional quantum Hall\nstates are gapped by proximity-coupling to superconductors and ferromagnets.\nThe most transparent example is that of a fractional quantum spin Hall state,\nin which electrons of one spin direction occupy a fractional quantum Hall state\nof $\\nu= 1/m$, while electrons of the opposite spin occupy a similar state with\n$\\nu = -1/m$. However, we also propose other examples of such systems, which\nare easier to realize experimentally. We find that each interface between a\nregion on the edge coupled to a superconductor and a region coupled to a\nferromagnet corresponds to a non-abelian anyon of quantum dimension\n$\\sqrt{2m}$. We calculate the unitary transformations that are associated with\nbraiding of these anyons, and show that they are able to realize a richer set\nof non-abelian representations of the braid group than the set realized by\nnon-abelian anyons based on Majorana fermions. We carry out this calculation\nboth explicitly and by applying general considerations. Finally, we show that\ntopological manipulations with these anyons cannot realize universal quantum\ncomputation."
    },
    {
        "anchor": "STEM image analysis based on deep learning: identification of vacancy\n  defects and polymorphs of ${MoS_2}$: Scanning transmission electron microscopy (STEM) is an indispensable tool for\natomic-resolution structural analysis for a wide range of materials. The\nconventional analysis of STEM images is an extensive hands-on process, which\nlimits efficient handling of high-throughput data. Here we apply a fully\nconvolutional network (FCN) for identification of important structural features\nof two-dimensional crystals. ResUNet, a type of FCN, is utilized in identifying\nsulfur vacancies and polymorph types of ${MoS_2}$ from atomic resolution STEM\nimages. Efficient models are achieved based on training with simulated images\nin the presence of different levels of noise, aberrations, and carbon\ncontamination. The accuracy of the FCN models toward extensive experimental\nSTEM images is comparable to that of careful hands-on analysis. Our work\nprovides a guideline on best practices to train a deep learning model for STEM\nimage analysis and demonstrates FCN's application for efficient processing of a\nlarge volume of STEM data.",
        "positive": "Thickness dependence of the anomalous Nernst effect and the Mott\n  relation of Weyl-semimetal Co2MnGa thin films: We report a robust anomalous Nernst effect in Co2MnGa thin films in the\nthickness regime between 20 and 50 nm. The anomalous Nernst coefficient varied\nin the range of -2.0 to -3.0 uV/K at 300 K. We demonstrate that the anomalous\nHall and Nernst coefficients exhibit similar behavior and fulfill the Mott\nrelation. We simultaneously measure all four transport coefficients of the\nlongitudinal resistivity, transversal resistivity, Seebeck coefficient, and\nanomalous Nernst coefficient. We connect the values of the measured and\ncalculated Nernst conductivity by using the remaining three magneto-thermal\ntransport coefficients, where the Mott relation is still valid. The intrinsic\nBerry curvature dominates the transport due to the relation between the\nlongitudinal and transversal transport. Therefore, we conclude that the Mott\nrelationship is applicable to describe the magneto-thermoelectric transport in\nWeyl semimetal Co2MnGa as a function of film thickness."
    },
    {
        "anchor": "Charged impurity scattering and mobility in gated silicon nanowires: We study the effects of charged impurity scattering on the electronic\ntransport properties of <110>-oriented Si nanowires in a gate-all-around\ngeometry, where the impurity potential is screened by the gate, gate oxide and\nconduction band electrons. The electronic structure of the doped nanowires is\ncalculated with a tight-binding method and the transport properties with a\nLandauer-Buttiker Green functions approach and the linearized Boltzmann\ntransport equation (LBTE) in the first Born approximation. Based on our\nnumerical results we argue that: (1) There are large differences between\nPhosphorous (P) and Boron (B) doped systems, acceptors behaving as tunnel\nbarriers for the electrons, while donors give rise to Fano resonances in the\ntransmission. (2) As a consequence, the mobility is much larger in P- than in\nB-doped nanowires at low carrier density, but can be larger in B-doped\nnanowires at high carrier density. (3) The resistance of a single impurity is\nstrongly dependent on its radial position in the nanowire, especially for\nacceptors. (4) As a result of subband structure and screening effects, the\nimpurity-limited mobility can be larger in thin nanowires embedded in HfO2 than\nin bulk Si. Acceptors might, however, strongly hinder the flow of electrons in\nthin nanowires embedded in SiO2. (5) The perturbative LBTE largely fails to\npredict the correct mobilities in quantum-confined nanowires.",
        "positive": "Spectrum of edge states in the $\u03bd=0$ quantum Hall phases in graphene: Edge excitations of the $\\nu=0$ quantum Hall state in monolayer graphene are\nstudied within the mean-field theory with different symmetry-breaking terms.\nThe analytical expressions for the continuum (Dirac) model wave functions are\nobtained for the charge density wave, Kekul\\'e distortion, ferromagnetic, and\n(canted) antiferromagnetic phases. The dispersion equations for each phase and\nboundary type (zigzag and armchair) are derived, numerically solved, and\ncompared to the results of the corresponding effective tight-binding model. The\neffect of the next-to-nearest neighbor hopping parameter on the edge state\nspectrum is studied and revealed to be essential. The criteria for the\nexistence of gapless edge states are established for each phase and edge type."
    },
    {
        "anchor": "Andreev reflection at the edge of a two-dimentional semimetal: We investigate electron transport through the interface between a niobium\nsuperconductor and the edge of a two-dimensional semimetal, realized in a 20~nm\nwide HgTe quantum well. Experimentally, we observe that typical behavior of a\nsingle Andreev contact is complicated by both a pronounced zero-bias resistance\nanomaly and shallow subgap resistance oscillations with $1/n$ periodicity.\nThese results are demonstrated to be independent of the superconducting\nmaterial and should be regarded as specific to a 2D semimetal in a proximity\nwith a superconductor. We interpret these effects to originate from the\nAndreev-like correlated process at the edge of a two-dimensional semimetal.",
        "positive": "Gain/loss induced localization in one-dimensional PT-symmetric\n  tight-binding models: We investigate the properties of PT-symmetric tight-binding models by\nconsidering both bounded and unbounded models. For the bounded case, we obtain\nclosed form expressions for the corresponding energy spectra and we analyze the\nstructure of eigenstates as well as their dependence on the gain/loss contrast\nparameter. For unbounded PT-lattices, we explore their scattering properties\nthrough the development of analytical models. Based on our approach we identify\na mechanism that is responsible to the emergence of localized states that are\nentirely due to the presence of gain and loss. The derived expressions for the\ntransmission and reflection coefficients allow one to better understand the\nrole of PT-symmetry in energy transport problems occurring in such PT-symmetric\ntight-binding settings. Our analytical results are further exemplified via\npertinent examples."
    },
    {
        "anchor": "Edge magnetoplasmons in graphene: Effects of gate screening and\n  dissipation: Magnetoplasmons on graphene edge in quantizing magnetic field are\ninvestigated at different Landau level filling factors. To find the mode\nfrequency, the optical conductivity tensor of disordered graphene in magnetic\nfield is calculated in the self-consistent Born approximation, and the nonlocal\nelectromagnetic problem is solved using the Wiener-Hopf method. Magnetoplasmon\ndispersion relations, velocities and attenuation lengths are studied\nnumerically and analytically with taking into account the screening by metallic\ngate and the energy dissipation in graphene. The magnetoplasmon velocity\ndecreases in the presence of nearby gate and oscillates as a function of the\nfilling factor because of the dissipation induced frequency suppression\noccurring when the Fermi level is located near the centers of Landau levels, in\nagreement with the recent experiments.",
        "positive": "Optical and magnetic measurements of gyroscopically stabilized graphene\n  nanoplatelets levitated in an ion trap: Using optical measurements, we demonstrate that the rotation of micron-scale\ngraphene nanoplatelets levitated in a quadrupole ion trap in high vacuum can be\nfrequency locked to an applied radio frequency (rf) electric field. Over time,\nfrequency locking stabilizes the nanoplatelet so that its axis of rotation is\nnormal to the nanoplatelet and perpendicular to the rf electric field. We\nobserve that residual slow dynamics of the direction of the axis of rotation in\nthe plane normal to the rf electric field are determined by an applied magnetic\nfield. We present a simple model that accurately describes our observations.\nFrom our data and model we can infer both a diamagnetic polarizability and a\nmagnetic moment proportional to the frequency of rotation, which we compare to\ntheoretical values. Our results establish that trapping technologies have\napplications for materials measurements at the nanoscale."
    },
    {
        "anchor": "Observations of Plasmarons in a System of Massive Electrons: Calculations of the single particle density of states (SPDOS) of electron\nliquids have long predicted that there exist two distinct charged excitations:\nthe usual quasiparticle consisting of an electron or hole screened by a\ncorrelation hole, and a \"plasmaron\" consisting of a hole resonantly bound to\nreal plasmons in the Fermi sea(1,2). Using tunneling spectroscopy to measure\nthe SPDOS of a two-dimensional electronic system, we demonstrate the first\ndetection of the plasmaron in a system in which electrons have mass. We monitor\nthe evolution of the plasmaron with applied magnetic field and discover\nunpredicted \"magnetoplasmarons\" which appear in spectra as negative index\nLandau levels. These sharp features corresponding to long-lived quasiparticles\nappear at high energies where SPDOS structure is ordinarily broadened by\nelectron-electron interactions.",
        "positive": "Thermosize potential in semiconductors: A thermosize junction consists of two different sized structures made by the\nsame material. Classical and quantum thermosize effects (CTSE and QTSE), which\nare opposite to each other, induce a thermosize potential in a thermosize\njunction. A semi-analytical method is proposed to calculate thermosize\npotentials in wide ranges of degeneracy and confinement by considering both\nCTSE and QTSE in thermosize junctions made by semiconductors. Dependencies of\nthermosize potential on temperature, size and degeneracy are examined. It is\nshown that a potential difference in millivolts scale can be induced as a\ncombined effect of CTSE and QTSE. The highest potential is obtained in\nnon-degenerate limit where the full analytical solution is obtained. The model\ncan be used to design semiconductor thermosize devices for a possible\nexperimental verification of CTSE and QTSE, which may lead to new nano energy\nconversion devices."
    },
    {
        "anchor": "An exact equilibrium reduced density matrix formulation I: The influence\n  of noise, disorder, and temperature on localization in excitonic systems: An exact method to compute the entire equilibrium reduced density matrix for\nsystems characterized by a system-bath Hamiltonian is presented. The approach\nis based upon a stochastic unraveling of the influence functional that appears\nin the imaginary time path integral formalism of quantum statistical mechanics.\nThis method is then applied to study the effects of thermal noise, static\ndisorder, and temperature on the coherence length in excitonic systems. As\nrepresentative examples of biased and unbiased systems, attention is focused on\nthe well-characterized light harvesting complexes of FMO and LH2, respectively.\nDue to the bias, FMO is completely localized in the site basis at low\ntemperatures, whereas LH2 is completely delocalized. In the latter, the\npresence of static disorder leads to a plateau in the coherence length at low\ntemperature that becomes increasingly pronounced with increasing strength of\nthe disorder. The introduction of noise, however, precludes this effect. In\nbiased systems, it is shown that the environment may increase the coherence\nlength, but only decrease that of unbiased systems. Finally it is emphasized\nthat for typical values of the environmental parameters in light harvesting\nsystems, the system and bath are entangled at equilibrium in the single\nexcitation manifold. That is, the density matrix cannot be described as a\nproduct state as is often assumed, even at room temperature. The reduced\ndensity matrix of LH2 is shown to be in precise agreement with the steady state\nlimit of previous exact quantum dynamics calculations.",
        "positive": "Electric Conductance of Rh Atomic Contacts under Electrochemical\n  Potential Control: The electric conductance of Rh atomic contacts was investigated under the\nelectrochemical potential control. The conductance histogram of Rh atomic\ncontacts varied with the electrochemical potential. When the electrochemical\npotential of the contact was kept at $\\Phi_{0}$= 0.1 V vs. Ag/AgCl (Rh\npotential), the conductance histogram did not show any features. At $\\Phi_{0}$=\n-0.1 V (under potential deposited hydrogen potential), the conductance\nhistogram showed a feature around 2.3 $G_{0}$ ($G_{0}$ =2$e^{2}/h$), which\nagreed with the conductance value of a clean Rh atomic contact, which was\nobserved in ultrahigh vacuum at low temperature. At $\\Phi_{0}$= -0.25 V (over\npotential deposited hydrogen potential), the conductance histogram showed\nfeatures around 0.3 and 1.0 $G_{0}$. The conductance behavior of the Rh atomic\ncontact was discussed by comparing previously reported results of other metals,\nAu, Ag, Cu, Pt, Pd, Ni, Co, and Fe. The conductance behavior of the metal\natomic contacts related with the strength of the interaction between hydrogen\nand metal surface."
    },
    {
        "anchor": "Longitudinal negative magnetoresistance and magneto-transport phenomena\n  in conventional and topological conductors: Recently a large negative longitudinal (parallel to the magnetic field)\nmagnetoresistance was observed in Weyl and Dirac semimetals. It is believed to\nbe related to the chiral anomaly associated with topological electron band\nstructure of these materials. We show that in a certain range of parameters\nsuch a phenomenon can also exist in conventional centrosymmetric and time\nreversal conductors, lacking topological protection of the electron spectrum\nand the chiral anomaly. We also discuss the magnetic field enhancement of the\nlongitudinal components of the thermal conductivity and thermoelectric tensors.",
        "positive": "Spin Hall effect in 2D metallic delafossite PtCoO$_2$ and vicinity\n  topology: The two-dimensional (2D) metal PtCoO$_2$ is renowned for the lowest room\ntemperature resistivity among all oxides, close to that of the top two\nmaterials Ag and Cu. In addition, we theoretically predict a strong intrinsic\nspin Hall effect. This originates from six strongly-tilted Dirac cones that we\nfind in the electronic structure near the Fermi surface, where a gap is opened\nby large spin-orbit coupling (SOC). This is underpinned by rich topological\nproperties; in particular, the phenomenology of a mirror Chern metal is\nrealized not exactly, but very accurately, on account of an approximate\ncrystalline symmetry. We expect that such 'vicinity topology' to be a feature\nof relevance well beyond this material. Our Wilson loop analysis indicates\nfurther elaborate features such as fragile topology. These findings highlight\nPtCoO$_2$ as a promising material for spintronic applications as well as a\nplatform to study the interplay of symmetry and topology."
    },
    {
        "anchor": "Graphene healing mechanisms: A theoretical investigation: Large holes in graphene membranes were recently shown to heal, either at room\ntemperature during a low energy STEM experiment, or by annealing at high\ntemperatures. However, the details of the healing mechanism remain unclear. We\ncarried out fully atomistic reactive molecular dynamics simulations in order to\naddress these mechanisms under different experimental conditions. Our results\nshow that, if a carbon atom source is present, high temperatures can provide\nenough energy for the carbon atoms to overcome the potential energy barrier and\nto produce perfect reconstruction of the graphene hexagonal structure. At room\ntemperature, this perfect healing is only possible if the heat effects of the\nelectron beam from STEM experiment are explicitly taken into account. The\nreconstruction process of a perfect or near perfect graphene structure involves\nthe formation of linear carbon chains, as well as rings containing 5, 6, 7 and\n8 atoms with planar (Stone-Wales) and non-planar (lump like) structures. These\nresults shed light on the healing mechanism of graphene when subjected to\ndifferent experimental conditions. Additionally, the methodology presented here\ncan be useful for investigating the tailoring and manipulations of other\nnano-structures.",
        "positive": "Evolution of shot noise in suspended lithographic gold break junctions\n  with bias and temperature: Shot noise is a powerful tool to probe correlations and microscopic transport\ndetails that conductance measurements alone cannot reveal. Even in atomic-scale\nAu devices that are well described by Landauer-B{\\\"u}ttiker physics,\ncomplications remain such as local heating and electron-phonon interactions. We\nreport systematic rf measurements of shot noise in individual atomic-scale gold\nbreak junctions at multiple temperatures, with most bias voltages well above\nthe energy of the Au optical phonon mode. Motivated by the previous\nexperimental evidence that electron-phonon interactions can modify Fano factors\nand result in kinked features in bias dependence of shot noise, we find that\nthe temperature dependence of shot noise from 4.2~K to 100~K is minimal.\nEnhanced Fano factors near 0.5$~G_0$ and features beyond simply linear bias\ndependence of shot noise near the 1$~G_0$ plateau are observed. Both are\nbelieved to have non-interacting origins and the latter likely results from\nslightly bias-dependent transmittance of the dominant quantum channel."
    },
    {
        "anchor": "Higher-Order Weyl-Exceptional-Ring Semimetals: For first-order topological semimetals, non-Hermitian perturbations can drive\nthe Weyl nodes into Weyl exceptional rings having multiple topological\nstructures and no Hermitian counterparts. Recently, it was discovered that\nhigher-order Weyl semimetals, as a novel class of higher-order topological\nphases, can uniquely exhibit coexisting surface and hinge Fermi arcs. However,\nnon-Hermitian higher-order topological semimetals have not yet been explored.\nHere, we identify a new type of topological semimetals, i.e, a higher-order\ntopological semimetal with Weyl exceptional rings. In such a semimetal, these\nrings are characterized by both a spectral winding number and a Chern number.\nMoreover, the higher-order Weyl-exceptional-ring semimetal supports both\nsurface and hinge Fermi-arc states, which are bounded by the projection of the\nWeyl exceptional rings onto the surface and hinge, respectively. Noticeably,\nthe dissipative terms can cause the coupling of two exceptional rings with\nopposite topological charges, so as to induce topological phase transitions.\nOur studies open new avenues for exploring novel higher-order topological\nsemimetals in non-Hermitian systems.",
        "positive": "The role of background impurities in the single particle relaxation\n  lifetime of a two-dimensional electron gas: We re-examine the quantum tau_q and transport tau_t scattering lifetimes due\nto background impurities in two-dimensional systems. We show that the\nwell-known logarithmic divergence in the quantum lifetime is due to the\nnon-physical assumption of an infinitely thick heterostructure, and demonstrate\nthat the existing non-divergent multiple scattering theory can lead to\nunphysical quantum scattering lifetimes in high quality heterostructures. We\nderive a non-divergent scattering lifetime for finite thickness structures,\nwhich can be used both with lowest order perturbation theory and the multiple\nscattering theory. We calculate the quantum and transport lifetimes for\nelectrons in generic GaAs-AlGaAs heterostructures, and find that the correct\n`rule of thumb' to distinguish the dominant scattering mechanisms in GaAs\nheterostructures should be tau_t/tau_q < 10 for background impurities and\ntau_t/tau_q > 10 for remote impurities. Finally we present the first comparison\nof theoretical results for tau_q and tau_t with experimental data from a GaAs\n2DEG in which only background impurity scattering is present. We obtain\nexcellent agreement between the calculations and experimental data, and are\nable to extract the background impurity density in both the GaAs and AlGaAs\nregions."
    },
    {
        "anchor": "Simultaneous Operations in a Two-Dimensional Array of Singlet-Triplet\n  Qubits: In many physical approaches to quantum computation, error-correction schemes\nassume the ability to form two-dimensional qubit arrays with nearest-neighbor\ncouplings and parallel operations at multiple qubit sites. While semiconductor\nspin qubits exhibit long coherence times relative to their operation speed and\nsingle-qubit fidelities above error correction thresholds, multiqubit\noperations in two-dimensional arrays have been limited by fabrication,\noperation, and readout challenges. We present a two-by-two array of four\nsinglet-triplet qubits in gallium arsenide and show simultaneous coherent\noperations and four-qubit measurements via exchange oscillations and\nfrequency-multiplexed single-shot measurements. A larger multielectron quantum\ndot is fabricated in the center of the array as a tunable interqubit link,\nwhich we utilize to demonstrate coherent spin exchange with selected qubits.\nOur techniques are extensible to other materials, indicating a path towards\nquantum processors with gate-controlled spin qubits.",
        "positive": "Coulomb Blockade and Insulator-to-Metal Quantum Phase Transition: We analyze an interplay between Coulomb blockade and quantum fluctuations in\na coherent conductor (with dimensionless conductance $g \\gtrsim 1$) attached to\nan Ohmic shunt. We demonstrate that at T=0 the system can be either an\ninsulator or a metal depending on whether its total resistance is larger or\nsmaller than $h/e^2\\approx 25.8$ k$\\Omega$. In a metallic phase the Coulomb gap\nis fully suppressed by quantum fluctuations. We briefly discuss possible\nrelation of this effect to recent experiments indicating the presence of a\nmetal-insulator phase transition in 2d disordered systems."
    },
    {
        "anchor": "Majorana boundary modes in Josephson junctions arrays with gapless bulk\n  excitations: The search for Majorana bound states in solid-state physics has been limited\nto materials which display a gap in their bulk spectrum. We show that such\nunpaired states appear in certain quasi-one-dimensional Josephson junctions\narrays with gapless bulk excitations. The bulk modes mediate a coupling between\nMajorana bound states via the Ruderman-Kittel-Yosida-Kasuya mechanism. As a\nconsequence, the lowest energy doublet acquires a finite energy difference. For\nrealistic set of parameters this energy splitting remains much smaller than the\nenergy of the bulk eigenstates even for short chains of length $L \\sim 10$.",
        "positive": "Giant enhancement of third-harmonic generation in graphene-metal\n  heterostructures: Nonlinear nanophotonics leverages engineered nanostructures to funnel light\ninto small volumes and intensify nonlinear optical processes with spectral and\nspatial control. Due to its intrinsically large and electrically tunable\nnonlinear optical response, graphene is an especially promising nanomaterial\nfor nonlinear optoelectronic applications. Here we report on exceptionally\nstrong optical nonlinearities in graphene-insulator-metal heterostructures,\ndemonstrating an enhancement by three orders of magnitude in the third-harmonic\nsignal compared to bare graphene. Furthermore, by increasing the graphene Fermi\nenergy through an external gate voltage, we find that graphene plasmons mediate\nthe optical nonlinearity and modify the third-harmonic signal. Our findings\nshow that graphene-insulator-metal is a promising heterostructure for\noptically-controlled and electrically-tunable nano-optoelectronic components."
    },
    {
        "anchor": "Harnessing transformation optics for understanding electron energy loss\n  and cathodoluminescence: As the continual experimental advances made in Electron energy loss\nspectroscopy (EELS) and cathodoluminescence (CL) open the door to practical\nexploitations of plasmonic effects in metal nanoparticles, there is an\nincreasing need for precise interpretation and guidance of such experiments.\nNumerical simulations are available but lack physical insight, while\ntraditional analytical approaches are rare and limited to studying specific,\nsimple structures. Here, we propose a versatile and efficient method based on\ntransformation optics which can fully characterize and model the EELS problems\nof nanoparticles of complex geometries. Detailed discussions are given on 2D\nand 3D nanoparticle dimers, where the frequency and time domain responses under\nelectron beam excitations are derived.",
        "positive": "Delocalization Transition of Disordered Axion Insulator: The axion insulator is a higher-order topological insulator protected by\ninversion symmetry. We show that under quenched disorder respecting inversion\nsymmetry {\\it on average}, the topology of the axion insulator stays robust,\nand an intermediate metallic phase in which states are delocalized is\nunavoidable at the transition from an axion insulator to a trivial insulator.\nWe derive this conclusion from general arguments, from classical percolation\ntheory, and from the numerical study of a 3D quantum network model simulating a\ndisordered axion insulator through a layer construction. We find the\nlocalization length critical exponent near the delocalization transition to be\n$\\nu=1.42\\pm 0.12$. We further show that this delocalization transition is\nstable even to weak breaking of the average inversion symmetry, up to a\ncritical strength. We also quantitatively map our quantum network model to an\neffective Hamiltonian and we find its low energy k$\\cdot$p expansion."
    },
    {
        "anchor": "Memory effects in black phosphorus field effect transistors: We report the fabrication and the electrical characterization of back-gated\nfield effect transistors with black phosphorus channel. We show that the\nhysteresis of the transfer characteristic, due to intrinsic defects, can be\nexploited to realize non-volatile memories. We demonstrate that gate voltage\npulses allow to trap and store charge inside the defect states, which enable\nmemory devices with endurance over 200 cycles and retention longer than 30\nminutes. We show that the use of a protective poly (methyl methacrylate) layer,\npositioned on top of the black phosphorus channel, does not affect the\nelectrical properties of the device but avoids the degradation caused by the\nexposure to air.",
        "positive": "Noise-compensating pulses for electrostatically controlled silicon spin\n  qubits: We study the performance of SUPCODE---a family of dynamically correcting\npulses designed to cancel simultaneously both Overhauser and charge noise for\nsinglet-triplet spin qubits---adapted to silicon devices with electrostatic\ncontrol. We consider both natural Si and isotope-enriched Si systems, and in\neach case we investigate the behavior of individual gates under static noise\nand perform randomized benchmarking to obtain the average gate error under\nrealistic 1/f noise. We find that in most cases SUPCODE pulses offer roughly an\norder of magnitude reduction in gate error, and especially in the case of\nisotope-enriched Si, SUPCODE yields gate operations of very high fidelity. We\nalso develop a version of SUPCODE that cancels the charge noise only, \"$\\delta\nJ$-SUPCODE\", which is particularly beneficial for isotope-enriched Si devices\nwhere charge noise dominates Overhauser noise, offering a level of error\nreduction comparable to the original SUPCODE while yielding gate times that are\n30% to 50% shorter. Our results show that the SUPCODE noise-compensating pulses\nprovide a fast, simple, and effective approach to error suppression, bringing\ngate errors well below the quantum error correction threshold in principle."
    },
    {
        "anchor": "Low Energy Properties of the Kondo chain in the RKKY regime: We study the Kondo chain in the regime of high spin concentration where the\nlow energy physics is dominated by the Ruderman-Kittel-Kasuya-Yosida (RKKY)\ninteraction. As has been recently shown (A. M. Tsvelik and O. M. Yevtushenko,\nPhys. Rev. Lett 115, 216402 (2015)), this model has two phases with drastically\ndifferent transport properties depending on the anisotropy of the exchange\ninteraction. In particular, the helical symmetry of the fermions is\nspontaneously broken when the anisotropy is of the easy plane type (EP). This\nleads to a parametrical suppression of the localization effects. In the present\npaper we substantially extend the previous theory, in particular, by analyzing\na competition of forward- and backward- scattering, including into the theory\nshort range electron interactions and calculating spin correlation functions.\nWe discuss applicability of our theory and possible experiments which could\nsupport the theoretical findings.",
        "positive": "Closely spaced and separately contacted 2d electron and 2d hole gases by\n  in situ focussed ion implantation: Separately contacted double layers of a 2d electron - 2d hole gases have been\nprepared in GaAs separated by thin AlGaAs barriers with thicknesses down to 15\nnm. The molecular-beam-epitaxial growth was interrupted just before the barrier\nin order to use in situ focussed-ion-beam implantation to pattern contacts\nwhich extend underneath the barrier. The two charge gases form upon biasing the\np- and n-type contacts underneath and above the barrier in forward direction\nand show independent transistor-like behavior."
    },
    {
        "anchor": "Hydrodynamic Equations in Quantum Hall Systems at Large Currents: Hydrodynamic equations (HDEQs) are derived which describe spatio-temporal\nevolutions of the electron temperature and the chemical potential of\ntwo-dimensional systems in strong magnetic fields in states with large diagonal\nresistivity appearing at the breakdown of the quantum Hall effect. The\nderivation is based on microscopic electronic processes consisting of drift\nmotions in a slowly-fluctuating potential and scattering processes due to\nelectron-electron and electron-phonon interactions. In contrast with the usual\nHDEQs, one of the derived HDEQs has a term with an energy flux perpendicular to\nthe electric field due to the drift motions in the magnetic field. As an\nillustration, the current distribution is calculated using the derived HDEQs.",
        "positive": "Strongly coupled magnon-plasmon polaritons in graphene- 2D ferromagnet\n  heterostructures: Magnons and plasmons are two very different types of collective modes, acting\non the spin and charge degrees of freedom, respectively. At first sight, the\nformation of hybrid plasmon-magnon polaritons in heterostructures of plasmonic\nand magnetic systems would face two challenges, the small mutual interaction,\nvia Zeeman coupling of the electromagnetic field of the plasmon with the spins,\nand the energy mismatch, as in most systems plasmons have energies in the eV\nrange, orders of magnitude larger than magnons. Here we show that graphene\nplasmons form polaritons with the magnons of two-dimensional ferrromagnetic\ninsulators, placed up to to half a micron apart, with Rabi couplings in the\nrange of 100 GHz (dramatically larger than cavity QED magnonics). This strong\ncoupling is facilitated both by the small energy of graphene plasmons and the\ncooperative super-radiant nature of the plasmon-magnon coupling afforded by\nphase matching. We show that the Rabi coupling can be modulated both\nelectrically and mechanically and we propose a attenuated total internal\nreflection experiment to implement ferromagnetic resonance experiments on 2D\nferromagnets driven by plasmon excitation."
    },
    {
        "anchor": "Spin Transport in the heterogeneous structure containing Topological\n  Insulator and Diluted Magnetic Semiconductor: In this paper, we discuss spin transport in topological insulator (TI) and\ndiluted magnetic semiconductor (DMS) heterogeneous structures. In DMS / FM\n(Ferromagnetic Metal) heterogeneous structure, the spin injection efficiency\nchanges according to the electric field and Fermi energy were investigated. The\nhigher electric field, the stronger spin injection efficiency, and its velocity\nof increase gets lower and approaches to the equilibrium state. Additionally,\nthe higher interface conductivity, the weaker spin injection efficiency, and\nthe transmission due to Fermi energy of spin up and spin down is different from\neach other. In the same structure, the spin injection efficiency changes\ndepending on the magnetic field, and the spin injection efficiency vibrates\nsensitively according to the magnetic field. In TI / DMS heterogeneous\nstructure, the spin current changes according to magnetic field were\ninvestigated. Here, when the magnetic field is low, the spin current\noscillates, and as the magnetic field increases, the vibration is attenuated.\nIt also decreases with increasing temperature and weakens vibrations. This is\ndue to the competitive effect of the chiral properties of Dirac type\nquasiparticles in the topological insulator and the unique properties of\nexchange interaction between electrons and ions in DMS. This result allows us\nto expect the possibility of spintronic devices with high sensitivity to\nmagnetic field.",
        "positive": "Quantum Point Contacts and Beyond: New Results on Mesoscopic Conductance\n  and Fluctuations: We summarize the main results of a microscopically based kinetic theory,\napplicable to open quantum point contacts (QPCs) driven up to high fields. The\ngoverning role of gauge invariance -- and the many-body sum rules for the\nelectron gas -- lead to stringent constraints on both transport and\nfluctuations. These constraints exert a dominant influence on the observable\nproperties of QPCs and similar open mesoscopic conductors. We illustrate this\nin the context of certain predictions within purely phenomenological models of\nmesoscopic transport."
    },
    {
        "anchor": "Orthogonality Catastrophe and Spontaneous Symmetry Breaking in\n  Double-layer Fermi-liquid-like States: The double-layer electron system with total filling factor $\\nu=1/2$ can be\nregarded as two separate Fermi-liquid-like states with $\\nu=1/4$ when the layer\nseparation is sufficiently large and there is no tunneling. The weak tunneling\nin this state suffers an orthogonality catastrophe and it becomes irrelevant.\nUsing the symmetric and antisymmetric combinations of layer indices as the\npseudospin degrees of freedom, we show that there exists the first order\ntransition from the above pseudospin unpolarized state to the pseudospin\npolarized Fermi-liquid-like state with $\\nu=1/2$ as the tunneling strength\nbecomes sufficiently large.",
        "positive": "Ultrafast switchable spin-orbit coupling for silicon spin qubits via\n  spin valves: Recent experimental breakthroughs, particularly for single-qubit and\ntwo-qubit gates exceeding the error correction threshold, highlight silicon\nspin qubits as leading candidates for fault-tolerant quantum computation. In\nthe existing architecture, intrinsic or synthetic spin-orbit coupling (SOC) is\ncritical in various aspects, including electrical control, addressability,\nscalability, etc. However, the high-fidelity SWAP operation and quantum state\ntransfer (QST) between spin qubits, crucial for qubit-qubit connectivity,\nrequire the switchable nature of SOC which is rarely considered. Here, we\npropose a flexible architecture based on spin valves by electrically changing\nits magnetization orientation within sub-nanoseconds to generate ultrafast\nswitchable SOC. Based on the switchable SOC architecture, both SWAP operation\nof neighbor spin qubits and resonant QST between distant spins can be realized\nwith fidelity exceeding 99% while considering the realistic experimental\nparameters. Benefiting from the compatible processes with the modern\nsemiconductor industry and experimental advances in spin valves and spin\nqubits, our results pave the way for future construction of silicon-based\nquantum chips."
    },
    {
        "anchor": "Enhanced Infrared Photodiodes Based on PbS/PbCl$_x$ Core/Shell\n  Nanocrystals: Improved passivation strategies to address the more complex surface structure\nof large-diameter nanocrystals are critical to the advancement of infrared\nphotodetectors based on colloidal PbS. In this contribution, the performance of\nshort-wave infrared (SWIR) photodiodes fabricated with PbS/PbCl$_x$\n(core/shell) nanocrystals versus their PbS-only (core) counterparts are\ndirectly compared. Despite their inherently similar bulk properties, devices\nusing PbS cores suffer from shunting and inefficient charge extraction, while\ncore/shell-based devices exhibit greater external quantum efficiencies and\nlower dark current densities. To elucidate the implications of the shell\nchemistry on device performance, the thickness-dependent energy level offsets\nand interfacial chemistry of the nanocrystal films with the zinc oxide\nelectron-transport layer are evaluated. The disparate device performance\nbetween the two synthetic methods is attributed to unfavorable interface dipole\nformation and surface defect states, associated with inadequate removal of the\nnative organic ligands in the core-only films. The core/shell system offers a\npromising route to manage the additional nonpolar (100) surface facets of\nlarger nanocrystals that conventional halide ligand treatments fail to\nsufficiently passivate.",
        "positive": "Disorder-induced two-body localised state in interacting quantum walks: We observe the onset of non-ergodicity from ballistic propagation of a\ntwo-body bound state in an interacting discrete-time quantum walk (DTQW) due to\ntime-dependent disorder in the interaction. The effect of the disorder on the\ntwo-body state can be interpreted as Anderson-type localisation in a projected\nDTQW, but without saturation of entanglement entropy. We characterise the\ntwo-body localisation in terms of the rate of growth of entanglement entropy\nand compute the localisation length. We find indications for two distinct\ngrowth laws for the entanglement: a logarithmic law in the delocalised phase\nand a double logarithmic law in the localised phase. We discuss similarities\nwith many-body localisation (MBL)."
    },
    {
        "anchor": "Engineering semiconductor hybrids for sensing: The effect of screening of the coulomb interaction between two layers of\ntwo-dimensional electrons, such as in graphene, by a highly doped\nsemiconducting substrate is investigated. We employ the random-phase\napproximation to calculate the dispersion equation of this hybrid structure in\norder to determine the plasmon excitation spectrum. When an electric current is\npassed through a layer, the low-frequency plasmons in the layer may bifurcate\ninto separate streams due to the current-driving effect. At a critical wave\nvector, determined by the separation between layers and their distance from the\nsurface, their phase velocities may be in opposite directions and a surface\nplasmon instability leads to the emission of radiation. Applications to\ndetectors and other electromagnetic devices exploiting nano-plasmonics are\ndiscussed.",
        "positive": "Molecule-based microelectromechanical sensors: Incorporating functional molecules into sensor devices is an emerging field\nin molecular electronics that aims at exploiting the sensitivity of different\nmolecules to their environment and turning it into an electrical signal. Among\nthe emergent sensors, microelectromechanical systems are promising for their\nextreme sensitivity to mechanical events. However, in order to bring new\nfunctions to these devices, the functionalization of their surface with\nmultifunctional molecules is required. Herein, we present original hybrid\ndevices made of an integrated polymer microelectromechanical resonator\nfunctionalized with switchable magnetic molecules. The change of their\nmechanical properties and geometry induced by the switching of their magnetic\nstate at a molecular level alters the device dynamical behavior, resulting in a\nchange of the resonance frequency. We demonstrate that the device can be\noperated to sense light or thermal excitation. Moreover, thanks to the\ncollective interaction of the switchable molecules, the device behaves as a\nnonvolatile memory. Our results open up broad prospects of new flexible photo\nand thermoactive hybrid devices for molecule based data storage and sensors."
    },
    {
        "anchor": "Weyl semimetals with a boundary at $z=0$ a photoemission study: We consider a Weyl semimetal with two nodes and derive the scattering\nHamiltonian in the presence of a boundary at $z=0$. We compute the\nphotoemission spectrum and demonstrate the presence of the Fermi arcs which\nconnect the two nodes. In the presence of an electric field parallel to the\nscattering surface we observe the one dimensional chiral anomaly.",
        "positive": "Phase Transitions in Systems with Finite Number of Atoms: Properties of nanoparticles have been studied within the framework of Ising\nmodel and the method of random-field interactions: the average magnetic moment\nand position of critical points of the magnetic and the concentration phase\ntransitions depending on their size. It is shown that the Curie temperature is\ninversely proportional to the size of the particle. Critical concentration of\nthe ordered state decreases with increasing of size of nanoparticles until the\npercolation threshold of \"massive\" particles."
    },
    {
        "anchor": "Topological gap solitons in a 1D non-Hermitian lattice: Nonlinear topological photonics is an emerging field aiming at extending the\nfascinating properties of topological states to the realm where interactions\nbetween the system constituents cannot be neglected. Interactions can indeed\ntrigger topological phase transitions, induce symmetry protection and\nrobustness properties for the many-body system. Moreover when coupling to the\nenvironment via drive and dissipation is also considered, novel collective\nphenomena are expected to emerge. Here, we report the nonlinear response of a\npolariton lattice implementing a non-Hermitian version of the\nSu-Schrieffer-Heeger model. We trigger the formation of solitons in the\ntopological gap of the band structure, and show that these solitons demonstrate\nrobust nonlinear properties with respect to defects, because of the underlying\nsub-lattice symmetry. Leveraging on the system non-Hermiticity, we engineer the\ndrive phase pattern and unveil bulk solitons that have no counterpart in\nconservative systems. They are localized on a single sub-lattice with a spatial\nprofile alike a topological edge state. Our results demonstrate a tool to\nstabilize the nonlinear response of driven dissipative topological systems,\nwhich may constitute a powerful resource for nonlinear topological photonics.",
        "positive": "Nonlocal Response of Metallic Nanospheres Probed by Light, Electrons,\n  and Atoms: Inspired by recent measurements on individual metallic nanospheres that can\nnot be explained with traditional classical electrodynamics, we theoretically\ninvestigate the effects of nonlocal response by metallic nanospheres in three\ndistinct settings: atomic spontaneous emission, electron energy loss\nspectroscopy, and light scattering. These constitute two near-field and one\nfar-field measurements, with zero-, one-, and two-dimensional excitation\nsources, respectively. We search for the clearest signatures of hydrodynamic\npressure waves in nanospheres. We employ a linearized hydrodynamic model and\nMie-Lorenz theory is applied for each case. Nonlocal response shows its mark in\nall three configurations, but for the two near-field measurements we predict\nespecially pronounced nonlocal effects that are not exhibited in far-field\nmeasurements. Associated with every multipole order is not only a single\nblueshifted surface plasmon, but also an infinite series of bulk plasmons that\nhas no counterpart in a local-response approximation. We show that these\nincreasingly blueshifted multipole plasmons become spectrally more prominent at\nshorter probe-to-surface separations and for decreasing nanosphere radii. For\nselected metals we predict hydrodynamic multipolar plasmons to be measurable on\nsingle nanospheres."
    },
    {
        "anchor": "Single-electron-parametron-based logic devices: We analyze the operation of the wireless single-electron logic family based\non single-electron-parametron cells. Parameter margins, energy dissipation, and\nthe error probability are calculated using the orthodox theory of\nsingle-electron tunneling. Circuits of this family enable quasi-reversible\ncomputation with energy dissipation per bit much lower than the thermal energy,\nand hence may circumvent one of the main obstacles faced by ultradense\nthree-dimensional integrated digital circuits.",
        "positive": "Field-Effect Control of Metallic Superconducting Systems: Despite metals are believed to be insensitive to field-effect and\nconventional Bardeen-Cooper-Schrieffer (BCS) theories predict the electric\nfield to be ineffective on conventional superconductors, a number of gating\nexperiments showed the possibility of modulating the conductivity of metallic\nthin films and the critical temperature of conventional superconductors. All\nthese experimental features have been explained by simple charge\naccumulation/depletion. In 2018, electric field control of supercurrent in\nconventional metallic superconductors has been demonstrated in a range of\nelectric fields where the induced variation of charge carrier concentration in\nmetals is negligibly small. In fact, no changes of normal state resistance and\nsuperconducting critical temperature were reported. Here, we review the\nexperimental results obtained in the realization of field-effect metallic\nsuperconducting devices exploiting this unexplained phenomenon. We will start\nby presenting the seminal results on superconducting BCS wires and\nnano-constriction Josephson junctions (Dayem bridges) made of different\nmaterials, such as titanium, aluminum and vanadium. Then, we show the mastering\nof the Josephson supercurrent in superconductor-normal metal-superconductor\nproximity transistors suggesting that the presence of induced superconducting\ncorrelations are enough to see this unconventional field-effect. Later, we\npresent the control of the interference pattern in a superconducting quantum\ninterference device indicating the coupling of the electric field with\nthesuperconducting phase. Among the possible applications of the presented\nphenomenology, we conclude this review by proposing some devices that may\nrepresent a breakthrough in superconducting quantum and classical computation."
    },
    {
        "anchor": "First observation of Aharonov-Bohm cages in 2-D normal metal networks: We report on magnetoresistance transport measurements performed on a\nbipartite tiling of rhombus in the GaAs/GaAlAs system. We observe for the first\ntime large amplitude $h/e$ oscillations in this network as compared to the one\nmeasured in square lattices of similar size. These oscillations are the\nsignature of a recently predicted localization phenomenon induced by\nAharonov-Bohm interferences in this peculiar network.",
        "positive": "Laser-beam patterned topological insulating states on thin\n  semiconducting MoS2: Identifying the two-dimensional (2D) topological insulating (TI) state in new\nmaterials and its control are crucial aspects towards the development of\nvoltage-controlled spintronic devices with low power dissipation. Members of\nthe 2D transition metal dichalcogenides (TMDCs) have been recently predicted\nand experimentally reported as a new class of 2D TI materials, but in most\ncases edge conduction seems fragile and limited to the monolayer phase\nfabricated on specified substrates. Here, we realize the controlled patterning\nof the 1T'-phase embedded into the 2H-phase of thin semiconducting\nmolybdenum-disulfide (MoS2) by laser beam irradiation. Integer fractions of the\nquantum of resistance, the dependence on laser-irradiation conditions, magnetic\nfield, and temperature, as well as the bulk gap observation by scanning\ntunneling spectroscopy and theoretical calculations indicate the presence of\nthe quantum spin Hall phase in our patterned 1T' phases."
    },
    {
        "anchor": "Transverse Quantum Confinement in Metal Nanofilms: Optical Spectra: We report optical absorption and photoluminescence spectra of Au, Fe, Co and\nNi polycrystalline nanofilms in the UV-Vis-NIR range, featuring discrete bands\nresulting from transverse quantum confinement. The film thickness ranged from\n1.1 to 15.6 nm, depending on the material. The films were deposited on fused\nsilica substrates by sputtering and thermo-evaporation, with Fe, Co and Ni\nprotected by a SiO2 film deposited on top. The results are interpreted within\nthe particle-in-a-box model, with the box width equal to the mass thickness of\nthe nanofilm. The transverse-quantized energy levels and transition energies\nscale as the inverse square of the film thickness. The calculated values of the\neffective electron mass are 0.93 (Au), 0.027 (Fe), 0.21 (Co) and 0.16 (Ni), in\nunits of the mass of the free electron, being independent on the film\nthickness. The uncertainties in the effective mass values are ca. 2.5%,\ndetermined by the film thickness calibration. The second calculated model\nparameter, the quantum number n of the HOMO, was thickness-independent in Au\n(5) and Fe (6), and increased with the film thickness in Co (from 7 to 9) and\nNi (from 7 to 11). The transitions observed in absorbance all start at the\nlevel n and correspond to {\\Delta}n = +1, +2, +3, etc. The photoluminescence\nbands exhibit large Stokes shifts, shifting to higher energies with the\nincreased excitation energy. The photoluminescence quantum yields grow linearly\nwith the excitation energy, showing evidence of multiple exciton generation. A\nprototype Fe-SnO2 nanofilm photovoltaic cell demonstrated at least 90% quantum\nyield of photoelectrons at 77K.",
        "positive": "Prevalence of two-dimensional photonic topology: The topological characteristics of photonic crystals have been the subject of\nintense research in recent years. Despite this, the basic question of whether\nphotonic band topology is rare or abundant -- i.e., its relative prevalence --\nremains unaddressed. Here, we determine the prevalence of stable, fragile, and\nhigher-order photonic topology in the 11 two-dimensional crystallographic\nsymmetry settings that admit diagnosis of one or more of these phenomena by\nsymmetry analysis. Our determination is performed on the basis of a data set of\n550000 randomly sampled, two-tone photonic crystals, spanning 11 symmetry\nsettings and 5 dielectric contrasts, and examined in both transverse electric\n(TE) and magnetic (TM) polarizations. We report the abundance of nontrivial\nphotonic topology in the presence of time-reversal symmetry and find that\nstable, fragile, and higher-order topology are generally abundant. Below the\nfirst band gap, which is of primary experimental interest, we find that stable\ntopology is more prevalent in the TE polarization than the TM; is only weakly,\nbut monotonically, dependent on dielectric contrast; and that fragile topology\nis near-absent. In the absence of time-reversal symmetry, nontrivial Chern\nphases are also abundant in photonic crystals with 2-, 4-, and 6-fold\nrotational symmetries but comparatively rare in settings with only 3-fold\nsymmetry. Our results elucidate the interplay of symmetry, dielectric contrast,\nelectromagnetic polarization, and time-reversal breaking in engendering\ntopological photonic phases and may inform general design principles for their\nexperimental realization."
    },
    {
        "anchor": "Aluminum Nanoparticles with Hot Spots for Plasmon-Induced Circular\n  Dichroism of Chiral Molecules in the UV Spectral Interval: Plasmonic nanocrystals with hot spots are able to localize optical energy in\nsmall spaces. In such physical systems, near-field interactions between\nmolecules and plasmons can become especially strong. This paper considers the\ncase of a nanoparticle dimer and a chiral biomolecule. In our model, a chiral\nmolecule is placed in the gap between two plasmonic nanoparticles, where the\nelectromagnetic hot spot occurs. Since many important biomolecules have optical\ntransitions in the UV, we consider the case of Aluminum nanoparticles, as they\noffer strong electromagnetic enhancements in the blue and UV spectral\nintervals. Our calculations show that the complex composed of a chiral molecule\nand an Al-dimer exhibits strong CD signals in the plasmonic spectral region. In\ncontrast to the standard Au- and Ag-nanocrystals, the Al system may have a much\nbetter spectral overlap between the typical biomolecule's optical transitions\nand the nanocrystals' plasmonic band. Overall, we found that Al nanocrystals\nused as CD antennas exhibit unique properties as compared to other commonly\nstudied plasmonic and dielectric materials. The plasmonic systems investigated\nin this study can be potentially used for sensing chirality of biomolecules,\nwhich is of interest in applications such as drug development.",
        "positive": "Fanout of 2 Triangle Shape Spin Wave Logic Gates: Having multi-output logic gates saves much energy because the same structure\ncan be used to feed multiple inputs of next stage gates simultaneously. This\npaper proposes novel triangle shape fanout of 2 spin wave Majority and XOR\ngates; the Majority gate is achieved by phase detection, whereas the XOR gate\nis achieved by threshold detection. The proposed logic gates are validated by\nmeans of micromagnetic simulations. Furthermore, the energy and delay are\nestimated for the proposed structures and compared with the state-of-the-art\nspin wave logic gates, and 16nm and 7nm CMOS. The results demonstrate that the\nproposed structures provide energy reduction of 25%-50% in comparison to the\nother 2-output spin-wave devices while having the same delay, and energy\nreduction between 43x and 0.8x when compared to the 16nm and 7nm CMOS while\nhaving delay overhead between 11x and 40x."
    },
    {
        "anchor": "Remote Dipolar Interactions for Objective Density Calibration and Flow\n  Control of Excitonic Fluids: In this paper we suggest a method to observe remote interactions of spatially\nseparated dipolar quantum fluids, and in particular of dipolar excitons in GaAs\nbilayer based devices. The method utilizes the static electric dipole moment of\ntrapped dipolar fluids to induce a local potential change on spatially\nseparated test dipoles. We show that such an interaction can be used for a\nmodel- independent, objective fluid density measurements, an outstanding\nproblem in this field of research, as well as for inter-fluid exciton flow\ncontrol and trapping. For a demonstration of the effects on realistic devices,\nwe use a full two-dimensional hydrodynamical model.",
        "positive": "Moir\u00e9 induced organization of size-selected Pt clusters soft landed on\n  epitaxial graphene: Two-dimensional hexagonal arrays of Pt nanoparticles (1.45 nm diameter) have\nbeen obtained by deposition of preformed and size selected Pt80 nanoparticles\non graphene. This original self-organization is induced, at room temperature,\nby the 2D periodic undulation (the moir\\'e pattern) of graphene epitaxially\ngrown on the Ir(111) surface. By means of complementary techniques (scanning\ntunneling microscopy, grazing incidence X ray scattering), the Pt clusters\nshapes and organization are characterized and the structural evolution during\nannealing is investigated. The soft-landed clusters remain quasi-spherical and\na large proportion appears to be pinned on specific moir\\'e sites. The\nquantitative determination of the proportion of organized clusters reveals that\nthe obtained hexagonal array of the almost spherical nanoparticles is stable up\nto 650 K, which is an indication of a strong cluster-surface interaction."
    },
    {
        "anchor": "Dual Operation of Gate-All-Around Silicon Nanowires at Cryogenic\n  Temperatures: FET and Quantum Dot: As CMOS structures are envisioned to host silicon spin qubits, and for\nco-integrating quantum systems with their classical control blocks, the\ncryogenic behaviour of such structures need to be investigated. In this paper\nwe characterize the electrical properties of Gate-All-Around (GAA) n-MOSFETs Si\nnanowires (NWs) from room temperature down to 1.7 K. We demonstrate that those\ndevices can operate both as transistor and host quantum dots at cryogenic\ntemperature. In the classical regime of the transistor we show improved\nperformances of the devices and in the quantum regime we show systematic\nquantum dots formation in GAA devices.",
        "positive": "Polarimetry in M\u00f6ssbauer spectroscopy with Synchrotron M\u00f6ssbauer\n  Source: We have tested the new experimental techniques in the M\\\"ossbauer\nspectroscopy with Synchrotron M\\\"ossbauer Source by using the polarization\nanalysis of the reflected radiation. In particular we have shown that the\ndichroic components in M\\\"ossbauer spectra create the scattering intensity with\n\"rotated\" polarization. The angular dependence for such component in the\nreflected signal is characterized by the peak near the critical angle of the\ntotal external reflection, and in the case of the collinear antiferromagnetic\ninterlayer ordering the \"magnetic\" maxima on the reflectivity curve are formed\nmainly by this \"rotated\" polarization. The first experiment on M\\\"ossbauer\nreflectivity with selection of the \"rotated\" polarization shows the expected\npeak near the critical angle. The measured M\\\"ossbauer reflectivity spectra of\nthe \"rotated\" polarization near the critical angle are rather different from\nthe M\\\"ossbauer reflectivity spectra, measured without polarization analysis.\nThey contain a smaller number of lines and can simplify the interpretation of\nthe poorly resolved spectra. The enhanced surface sensitivity of the new\ntechnique is discussed."
    },
    {
        "anchor": "Competition between disorder and interaction effects in 3D Weyl\n  semimetals: We investigate the low-energy scaling behavior of an interacting 3D Weyl\nsemimetal in the presence of disorder. In order to achieve a renormalization\ngroup analysis of the theory, we focus on the effects of a\nshort-ranged-correlated disorder potential, checking nevertheless that this\nchoice is not essential to locate the different phases of the Weyl semimetal.\nWe show that there is a line of fixed-points in the renormalization group flow\nof the interacting theory, corresponding to the disorder-driven transition to a\ndiffusive metal phase. Along that boundary, the critical disorder strength\nundergoes a strong increase with respect to the noninteracting theory, as a\nconsequence of the unconventional screening of the Coulomb and disorder-induced\ninteractions. A complementary resolution of the Schwinger-Dyson equations\nallows us to determine the full phase diagram of the system, showing the\nprevalence of a renormalized semimetallic phase in the regime of intermediate\ninteraction strength, and adjacent to the non-Fermi liquid phase characteristic\nof the strong interaction regime of 3D Weyl semimetals.",
        "positive": "Spin current injection by intersubband transitions in quantum wells: We show that a pure spin current can be injected in quantum wells by the\nabsorption of linearly polarized infrared radiation, leading to transitions\nbetween subbands. The magnitude and the direction of the spin current depend on\nthe Dresselhaus and Rashba spin-orbit coupling constants and light frequency\nand, therefore, can be manipulated by changing the light frequency and/or\napplying an external bias across the quantum well. The injected spin current\nshould be observable either as a voltage generated via the anomalous spin-Hall\neffect, or by spatially resolved pump-probe optical spectroscopy."
    },
    {
        "anchor": "Direct observation of water mediated single proton transport between hBN\n  surface defects: Aqueous proton transport at interfaces is ubiquitous and crucial for a number\nof fields, ranging from cellular transport and signaling, to catalysis and\nmembrane science. However, due to their light mass, small size and high\nchemical reactivity, uncovering single proton surface transport at room\ntemperature and in aqueous environment has so far remained out-of-reach of\nconventional atomic-scale surface science techniques, such as STM. Here, we use\nsingle-molecule localization microscopy techniques to resolve optically the\ntransport of individual excess protons at the interface of hexagonal boron\nnitride crystals and aqueous solutions at room temperature. Our label-free\napproach relies on the successive protonation and activation of optically\nactive defects at the surface of the crystal allowing us to resolve interfacial\nproton transport at the single molecule scale with nanometric resolution and\nover micrometer range. Proton trajectories are revealed as a succession of\njumps between proton-binding defects, mediated by interfacial water. We\ndemonstrate unexpected interfacial proton mobility under illumination, limited\nby proton desorption from individual defects. The proposed mechanism is\nsupported by ab initio molecular dynamics simulations of defected and pristine\nhBN/water interface. Our observations provide direct experimental evidence at\nthe single molecule scale that interfacial water provides a preferential\npathway for lateral proton transport. Our findings have fundamental and general\nimplications for water-mediated molecular charge transport at interfaces.",
        "positive": "Pseudo-ballistic transport in 3D topological insulator quantum wires: Quantum conductance fluctuations are investigated in disordered 3D\ntopological insulator quantum wires. Both experiments and theory reveal a new\ntransport regime in a mesoscopic conductor, pseudo-ballistic transport, for\nwhich ballistic properties persist beyond the transport mean free path,\ncharacteristic of diffusive transport. It results in non-universal conductance\nfluctuations due to quasi-1D surface modes, as observed in long and narrow\nBi$_2$Se$_3$ nanoribbons. Spin helical Dirac fermions in quantum wires retain\npseudo-ballistic properties over an unusually broad energy range, due to strong\nquantum confinement and weak momentum scattering."
    },
    {
        "anchor": "Multi-dimensional laser spectroscopy of exciton-polaritons with spatial\n  light modulators: We describe an experimental system that allows one to easily access the\ndispersion curve of exciton-polaritons in a microcavity. Our approach is based\non two spatial light modulators (SLM), one for changing the excitation angles\n(momenta), and the other for tuning the excitation wavelength. We show that\nwith this setup, an arbitrary number of states can be excited accurately and\nthat re-configuration of the excitation scheme can be done at high speed.",
        "positive": "First principles study of Si(335)-Au surface: The structural and electronic properties of gold decorated Si(335) surface\nare studied by means of density-functional calculations. The resulting\nstructural model indicates that the Au atoms substitute some of the Si atoms in\nthe middle of the terrace in the surface layer. Calculated electronic band\nstructure near the Fermi energy features two metallic bands, one coming from\nthe step edge Si atoms and the other one having its origin in hybridization\nbetween the Au and neighboring Si atoms in the middle of the terrace. The\nobtained electronic bands remain in good agreement with photoemission data."
    },
    {
        "anchor": "Manipulating Majorana fermions using supercurrents: Topological insulator edges and spin-orbit-coupled quantum wires in proximity\nto s-wave super- conductors can be tuned through a topological quantum phase\ntransition by a Zeeman field. Here we show that a supercurrent flowing in the\ns-wave superconductor also drives such a transition. We propose to use this new\nmechanism to generate and manipulate Majorana fermions that localize at domain\nwalls between topological and nontopological regions of an edge or wire. In\nquantum wires, this method carries the added benefit that a supercurrent\nreduces the critical Zeeman field at which the topological phase appears.",
        "positive": "Quantum Spin Hall Insulator State in HgTe Quantum Wells: Recent theory predicted that the Quantum Spin Hall Effect, a fundamentally\nnovel quantum state of matter that exists at zero external magnetic field, may\nbe realized in HgTe/(Hg,Cd)Te quantum wells. We have fabricated such sample\nstructures with low density and high mobility in which we can tune, through an\nexternal gate voltage, the carrier conduction from n-type to the p-type,\npassing through an insulating regime. For thin quantum wells with well width d\n< 6.3 nm, the insulating regime shows the conventional behavior of vanishingly\nsmall conductance at low temperature. However, for thicker quantum wells (d >\n6.3 nm), the nominally insulating regime shows a plateau of residual\nconductance close to 2e^2/h. The residual conductance is independent of the\nsample width, indicating that it is caused by edge states. Furthermore, the\nresidual conductance is destroyed by a small external magnetic field. The\nquantum phase transition at the critical thickness, d = 6.3 nm, is also\nindependently determined from the magnetic field induced insulator to metal\ntransition. These observations provide experimental evidence of the quantum\nspin Hall effect."
    },
    {
        "anchor": "$\u03c0$-Radical Formation by Pyrrolic H Abstraction of Phthalocyanine\n  Molecules on Molybdenum Disulfide: For a molecular radical to be stable, the environment needs to be inert.\nFurthermore, an unpaired electron is less likely to react chemically, when it\nis placed in an extended orbital. Here, we use the tip of a scanning tunneling\nmicroscope to abstract one of the pyrrolic hydrogen atoms from phthalocyanine\n(H2Pc) deposited on a single layer of molybdenum disulfide (MoS2) on Au(111).\nWe show the successful dissociation reaction by current-induced three-level\nfluctuations reflecting the inequivalent positions of the remaining H atom in\nthe pyrrole center. Tunneling spectroscopy reveals two narrow resonances inside\nthe semiconducting energy gap of MoS2 with their spatial extent resembling the\nhighest occupied molecular orbital (HOMO) of H2Pc. By comparison to simple\ndensity functional calculations of the isolated molecule, we show that these\ncorrespond to a single occupation of the Coulomb-split highest molecular\norbital of HPc. We conclude that the dangling $\\sigma$ bond after N-H bond\ncleavage is filled by an electron from the delocalized HOMO. The extended\nnature of the HOMO together with the inert nature of the MoS2 layer favor the\nstabilization of this radical state.",
        "positive": "Voltage induced conversion of helical to uniform nuclear spin\n  polarization in a quantum wire: We study the effect of bias voltage on the nuclear spin polarization of a\nballistic wire, which contains electrons and nuclei interacting via hyperfine\ninteraction. In equilibrium, the localized nuclear spins are helically\npolarized due to the electron-mediated Ruderman-Kittel-Kasuya-Yosida (RKKY)\ninteraction. Focusing here on non-equilibrium, we find that an applied bias\nvoltage induces a uniform polarization, from both helically polarized and\nunpolarized spins available for spin flips. Once a macroscopic uniform\npolarization in the nuclei is established, the nuclear spin helix rotates with\nfrequency proportional to the uniform polarization. The uniform nuclear spin\npolarization monotonically increases as a function of both voltage and\ntemperature, reflecting a thermal activation behavior. Our predictions offer\nspecific ways to test experimentally the presence of a nuclear spin helix\npolarization in semiconducting quantum wires."
    },
    {
        "anchor": "Electronic spectral properties of incommensurate twisted trilayer\n  graphene: Multilayered van der Waals structures often lack periodicity, which\ndifficults their modeling. Building on previous work for bilayers, we develop a\ntight-binding based, momentum space formalism capable of describing\nincommensurate multilayered van der Waals structures for arbitrary lattice\nmismatch and/or misalignment between different layers. We demonstrate how the\ndeveloped formalism can be used to model angle-resolved photoemission\nspectroscopy measurements, and scanning tunnelling spectroscopy which can probe\nthe local and total density of states. The general method is then applied to\nincommensurate twisted trilayer graphene structures. It is found that the\ncoupling between the three layers can significantly affect the low energy\nspectral properties, which cannot be simply attributed to the pairwise\nhybridization between the layers.",
        "positive": "Cooling and heating with electron spins: Observation of the spin Peltier\n  effect: The Peltier coefficient describes the amount of heat that is carried by an\nelectrical current when it passes through a material. Connecting two materials\nwith different Peltier coefficients causes a net heat flow towards or away from\nthe interface, resulting in cooling or heating at the interface - the Peltier\neffect. Spintronics describes the transport of charge and angular momentum by\nmaking use of separate spin-up and spin-down channels. Recently, the merger of\nthermoelectricity with spintronics has given rise to a novel and rich research\nfield named spin caloritronics. Here, we report the first direct experimental\nobservation of refrigeration/heating driven by a spin current, a new spin\nthermoelectric effect which we call the spin Peltier effect. The heat flow is\ngenerated by the spin dependency of the Peltier coefficient inside the\nferromagnetic material. We explored the effect in a specifically designed spin\nvalve pillar structure by measuring the temperature using an electrically\nisolated thermocouple. The difference in heat flow between the two magnetic\nconfigurations leads to a change in temperature. With the help of 3-D finite\nelement modeling, we extracted permalloy spin Peltier coefficients in the range\nof -0.9 to -1.3 mV. These results enable magnetic control of heat flow and\nprovide new functionality for future spintronic devices."
    },
    {
        "anchor": "Engineering a spin-fet: spin-orbit phenomena and spin transport induced\n  by a gate electric field: In this work, we show that a gate electric field, applied in the base of the\nfield-effect devices, leads to inducing spin-orbit interactions (Rashba and\nlinear Dresselhauss) and confines the transport electrons in a two-dimensional\nelectron gas. On the basis of these phenomena we solve analytically the Pauli\nequation when the Rashba strength and the linear Dresselhaus one are equal, for\na tuning value of the gate electric field $\\mathcal{E}_g^*$. Using the transfer\nmatrix approach, we provide a joint description of the transport by varying the\nbias electric field, $\\mathcal{E}_b$. We can flip the spin of the incident\nelectrons, or block the spin-down completely. The robustness of this behavior\nis proved when $\\mathcal{E}_g^*$ changes by $\\mathcal{E}_g^* \\pm \\delta\n\\mathcal{E}_g$.",
        "positive": "Current dependence of spin torque switching rate based on Fokker-Planck\n  approach: The spin torque switching rate of an in-plane magnetized system in the\npresence of an applied field is derived by solving the Fokker-Planck equation.\nIt is found that three scaling currents are necessary to describe the current\ndependence of the switching rate in the low-current limit. The dependences of\nthese scaling currents on the applied field strength are also studied."
    },
    {
        "anchor": "Bias and temperature dependence of the 0.7 conductance anomaly in\n  Quantum Point Contacts: The 0.7 (2e^2/h) conductance anomaly is studied in strongly confined, etched\nGaAs/GaAlAs quantum point contacts, by measuring the differential conductance\nas a function of source-drain and gate bias as well as a function of\ntemperature. We investigate in detail how, for a given gate voltage, the\ndifferential conductance depends on the finite bias voltage and find a\nso-called self-gating effect, which we correct for. The 0.7 anomaly at zero\nbias is found to evolve smoothly into a conductance plateau at 0.85 (2e^2/h) at\nfinite bias. Varying the gate voltage the transition between the 1.0 and the\n0.85 (2e^2/h) plateaus occurs for definite bias voltages, which defines a gate\nvoltage dependent energy difference $\\Delta$. This energy difference is\ncompared with the activation temperature T_a extracted from the experimentally\nobserved activated behavior of the 0.7 anomaly at low bias. We find \\Delta =\nk_B T_a which lends support to the idea that the conductance anomaly is due to\ntransmission through two conduction channels, of which the one with its subband\nedge \\Delta below the chemical potential becomes thermally depopulated as the\ntemperature is increased.",
        "positive": "Nonlinear dynamics of topological helicity wave in a frustrated skyrmion\n  string: A skyrmion in frustrated magnetic system has the helicity degree of freedom.\nA skyrmion string is formed in a frustrated layered system, which is well\ndescribed by the $XY$ model owing to the exchange coupling between adjacent\nlayers. We consider a system where the interlayer exchange couplings are\nalternating, where the dimerized $XY$ model is materialized, whose linear limit\nis the Su-Schrieffer-Heeger model. We argue that it is a nonlinear topological\nsystem. We study the quench dynamics of the helicity wave under the initial\ncondition that the helicity of the skyrmion in the bottommost layer is rotated.\nIt yields a good signal to detect whether the system is topological or trivial.\nOur results show that the helicity dynamics of the skyrmion string have a rich\nphysics in the modulated exchange-coupled system."
    },
    {
        "anchor": "Topological protection of Majorana polaritons in a cavity: Cavity embedding is an emerging paradigm for the control of quantum matter,\noffering avenues to manipulate electronic states and potentially drive\ntopological phase transitions. In this work, we address the stability of a\none-dimensional topological superconducting phase to the vacuum quantum\nfluctuations brought by a global cavity mode. By employing a quasi-adiabatic\nanalytical approach completed by density matrix renormalization group\ncalculations, we show that the Majorana end modes evolve into composite\npolaritonic modes while maintaining the topological order intact and robust to\ndisorder. These Majorana polaritons keep their non-abelian exchange properties\nand protect a twofold exponentially degenerate ground state for an open chain.",
        "positive": "Quantum oscillations of the magnetic torque in the nodal-line Dirac\n  semimetal ZrSiS: We report a study of quantum oscillations (QO) in the magnetic torque of the\nnodal-line Dirac semimetal ZrSiS in the magnetic fields up to 35 T and the\ntemperature range from 40 K down to 2 K, enabling high resolution mapping of\nthe Fermi surface (FS) topology in the $k_z=\\pi$ (Z-R-A) plane of the first\nBrillouin zone (FBZ). It is found that the oscillatory part of the measured\nmagnetic torque signal consists of low frequency (LF) contributions\n(frequencies up to 1000 T) and high frequency (HF) contributions (several\nclusters of frequencies from 7-22 kT). Increased resolution and angle-resolved\nmeasurements allow us to show that the high oscillation frequencies originate\nfrom magnetic breakdown (MB) orbits involving clusters of individual $\\alpha$\nhole and $\\beta$ electron pockets from the diamond shaped FS in the Z-R-A\nplane. Analyzing the HF oscillations we have unequivocally shown that the QO\nfrequency from the dog-bone shaped Fermi pocket ($\\beta$ pocket) amounts\n$\\beta=591(15)$ T. Our findings suggest that most of the frequencies in the LF\npart of QO can also be explained by MB orbits when intraband tunneling in the\ndog-bone shaped $\\beta$ electron pocket is taken into account. Our results give\na new understanding of the novel properties of the FS of the nodal-line Dirac\nsemimetal ZrSiS and sister compounds."
    },
    {
        "anchor": "Comment on \"Photon energy and carrier density dependence of spin\n  dynamics in bulk CdTe crystal at room temperature\": We comment on the conclusion by Ma et al. [Appl. Phys. Lett. {\\bf 94}, 241112\n(2009)] that the Elliott-Yafet mechanism is more important than the\nD'yakonov-Perel' mechanism at high carrier density in intrinsic bulk CdTe at\nroom temperature. We point out that the spin relaxation is solely from the\nD'yakonov-Perel' mechanism. The observed peak in the density dependence of spin\nrelaxation time is exactly what we predicted in a recent work [Phys. Rev. B\n{\\bf 79}, 125206 (2009)].",
        "positive": "Estimation of Young's Modulus of Graphene by Raman Spectroscopy: The Young's modulus of graphene is estimated by measuring the strain applied\nby a pressure difference across graphene membranes using Raman spectroscopy.\nThe strain induced on pressurized graphene balloons can be estimated directly\nfrom the peak shift of the Raman G band. By comparing the measured strain with\nnumerical simulation, we obtained the Young's modulus of graphene. The\nestimated Young's modulus values of single- and bi-layer graphene are 2.4\\pm0.4\nTPa and 2.0\\pm0.5 TPa, respectively."
    },
    {
        "anchor": "Correlating spin transport and electrode magnetization in a graphene\n  spin valve: simultaneous magnetic microscopy and non-local measurements: Using simultaneous magnetic force microscopy (MFM) and transport measurements\nof a graphene spin valve, we correlate the non-local spin signal with the\nmagnetization of the device electrodes. The imaged magnetization states\ncorroborate the influence of each electrode within a one-dimensional spin\ntransport model and provide evidence linking domain wall pinning to additional\nfeatures in the transport signal.",
        "positive": "Dynamical properties of a vibrating molecular quantum dot in a Josephson\n  junction: We investigate dynamical transport aspects of a combined\nnanomechanical-superconducting device in which Cooper pair tunneling interfere\nwith the mechanical motion of a vibrating molecular quantum dot embedded in a\nJosephson junction. Six different regimes for the tunneling dynamics are\nidentified with respect to the electron level and the charging energy in the\nquantum dot. In five of those regimes new time-scales are introduced which are\nassociated with the energies of the single electron transitions within the\nquantum dot, while there is one regime where the internal properties of the\nquantum dot are static."
    },
    {
        "anchor": "An opto-electro-mechanical system based on evanescently-coupled optical\n  microbottle and electromechanical resonator: Evanescent coupling between a silica optical microbottle resonator and a GaAs\nelectromechanical resonator is demonstrated. This coupling provides high\noptical sensitivity and efficient piezoelectric controllability of mechanical\nmotion. Opto-electro-mechanical feedback control based on optomechanical\ndetection and electromechanical control is performed in both heating and\ncooling regimes at room temperature. This feedback scheme can be extended to\nthe efficient control of thermal mechanical motion in electromechanical\nresonators with arbitrary structures and materials.",
        "positive": "Quantum graphs and the integer quantum Hall effect: We study the spectral properties of infinite rectangular quantum graphs in\nthe presence of a magnetic field. We study how these properties are affected\nwhen three-dimensionality is considered, in particular, the chaological\nproperties. We then establish the quantization of the Hall transverse\nconductivity for these systems. This quantization is obtained by relating the\ntransverse conductivity to topological invariants. The different integer values\nof the Hall conductivity are explicitly computed for an anisotropic diffusion\nsystem which leads to fractal phase diagrams."
    },
    {
        "anchor": "Ultrashort electron wavepackets via frequency-comb synthesis: Single-electron sources are an essential component of modern quantum\nnanoelectronic devices. Owing to their high accuracy and stability, they have\nbeen successfully employed for metrology applications, studying fundamental\nmatter interactions and more recently for electron quantum optics. They are\ntraditionally driven by state-of-the-art arbitrary waveform generators that are\ncapable of producing single-electron pulses in the sub-100 ps timescale. In\nthis work, we use an alternative approach for generating ultrashort electron\nwavepackets. By combining several harmonics provided by a frequency comb, we\nsynthesise Lorentzian voltage pulses and then use them to generate electron\nwavepackets. Through this technique, we report on the generation and detection\nof an electron wavepacket with temporal duration of 27 ps generated on top of\nthe Fermi sea of a 2-dimensional electron gas - the shortest reported to date.\nElectron pulses this short enable studies on elusive, ultrafast fundamental\nquantum dynamics in nanoelectronic systems and pave the way to implement flying\nelectron qubits by means of Levitons.",
        "positive": "Non-unitary multiorbital superconductivity from competing interactions\n  in Dirac materials: Unconventional superconductors represent one of the most intriguing quantum\nstates of matter. In particular, multiorbital systems have the potential to\nhost exotic non-unitary superconducting states. While the microscopic origin of\nnon-unitarity is not yet fully solved, competing interactions are suggested to\nplay a crucial role in stabilizing such states. The interplay between charge\norder and superconductivity has been a recurring theme in unconventionally\nsuperconducting systems, ranging from cuprate-based superconductors to\ndichalcogenide systems and even to twisted van der Waals materials. Here, we\ndemonstrate that the existence of competing interactions gives rise to a\nnon-unitary superconducting state. We show that the non-unitarity stems from a\ncompeting charge-ordered state whose interplay with superconductivity promotes\na non-trivial multiorbital order. We establish this mechanism both from a\nGinzburg-Landau perspective, and also from a fully microscopic selfconsistent\nsolution of a multiorbital Dirac material. Our results put forward competing\ninteractions as a powerful mechanism for driving non-unitary multiorbital\nsuperconductivity."
    },
    {
        "anchor": "Pairs of Bloch electrons and magnetic translation groups: A product of irreducible representations of magnetic translation group is\nconsidered. It leads to irreducible representations which were previously\nrejected as nonphysical. A very simple example indicates a possible application\nof these representations. In particular, they are important in descriptions of\npairs of electrons in a magnetic field and a periodic potential. The\nperiodicity of some properties with respect to the charge of a particle is\nbriefly discussed.",
        "positive": "Excitonic Bloch-Siegert shift in CsPbI3 perovskite quantum dots: Coherent interaction between matter and periodic light field induces both\noptical Stark effect (OSE) and Bloch-Siegert shift (BSS). Observing the BSS has\nbeen historically challenging, not only because it is weak but it is often\naccompanied by a much stronger OSE. Herein, by controlling the light helicity,\nwe can largely restrict the OSE and BSS to different spin-transitions in CsPbI3\nperovskite quantum dots, achieving room-temperature BSS as strong as 4 meV with\nnear-infrared pulses. The ratio between the BSS and OSE magnitudes is however\nsystematically higher than the prediction by the non-interacting,\nquasi-particle picture. With a model that explicitly accounts for excitonic\neffects, we quantitatively reproduce the experimental observations. This model\ndepicts a unified physical picture of the interplay between the OSE,\nbiexcitonic OSE and BSS in low-dimensional materials displaying strong\nmany-body interactions, forming the basis for the implementation of these\neffects to information processing, optical modulation and Floquet engineering."
    },
    {
        "anchor": "Magneto-transport Effects in Topological Insulator Bi$_2$Se$_3$\n  Nanoribbons: Magneto-resistance (MR) of Bi$_2$Se$_3$ nanoribbons is studied over a broad\nrange of temperature ($T$=300K-2K) and under various magnetic field ($B$)\norientations. The MR is strongly anisotropic with the perpendicular MR much\nlarger than the longitudinal and transverse MRs. The perpendicular MR exhibits\nquadratic $B$-dependence in low fields and becomes linear at high $B$. However,\nwhen $T$ increases, the perpendicular MR becomes linear over the whole magnetic\nfield range (0-9T) up to room temperature. This unusual linear MR is discussed\nin the context of the linear quantum MR of the topological surface-states. We\nalso observe the boundary-scattering effect in MR at low temperatures, which\nindicates that the out-of-plane Fermi momentum is much smaller the in-plane\nFermi momentum, excluding the simple three-dimensional Fermi surface picture.",
        "positive": "Observation of a One-Dimensional Spin-Orbit Gap in a Quantum Wire: Understanding the flow of spins in magnetic layered structures has enabled an\nincrease in data storage density in hard drives over the past decade of more\nthan two orders of magnitude1. Following this remarkable success, the field of\n'spintronics' or spin-based electronics is moving beyond effects based on local\nspin polarisation and is turning its attention to spin-orbit interaction (SOI)\neffects, which hold promise for the production, detection and manipulation of\nspin currents, allowing coherent transmission of information within a device.\nWhile SOI-induced spin transport effects have been observed in two- and\nthree-dimensional samples, these have been subtle and elusive, often detected\nonly indirectly in electrical transport or else with more sophisticated\ntechniques. Here we present the first observation of a predicted 'spin-orbit\ngap' in a one-dimensional sample, where counter-propagating spins, constituting\na spin current, are accompanied by a clear signal in the easily-measured linear\nconductance of the system."
    },
    {
        "anchor": "Linear Algebra with Disordered Sparse Matrices that have Spatial\n  Structure: Theory and Computation: This Ph.D. thesis contains original contributions to several areas within the\ndisciplines of disordered systems, numerical linear algebra, and scientific\ncomputing: (1) Theoretical and numerical study of the errors caused by using\ncertain O(N) algorithms for evaluating matrix functions. (2) Numerical results\non the localization of matrix functions, and on the length scales of\neigenfunctions. (3) A simple model which generalizes Berry's model of\nwavefunctions in chaotic systems to include both localization and\nmultifractality. (4) A proposal of a new sigma model for disordered systems\nwhich does not involve graded matrixes but should reproduce the same results as\nthe supersymmetric sigma model. A detailed derivation of the new sigma model is\nprovided. (5) Proposals for many new O(N) algorithms, and for many O(N log N)\nalgorithms suitable to systems with many length scales. (6) A review of the\nproblems which computing can cause for the physics community, and of the\nphysics community's current efforts to handle those problems. Following this\nreview is a set of recommendations for better managing these problems.",
        "positive": "Tight-Binding Bandstructure of $\u03b2-$ and $\u03b1-$ phase Ga$_2$O$_3$\n  and Al$_2$O$_3$: Rapid design and development of the emergent ultra-wide bandgap\nsemiconductors Ga$_2$O$_3$ and Al$_2$O$_3$ requires a compact model of their\nelectronic structures, accurate over the broad energy range accessed in future\nhigh-field, high-frequency, and high-temperature electronics and visible and\nultraviolet photonics. A minimal tight-binding model is developed to reproduce\nthe first-principles electronic structures of the $\\beta-$ and $\\alpha-$ phases\nof Ga$_2$O$_3$ and Al$_2$O$_3$ throughout their reciprocal spaces. Accurately\nreproducing the bandgap, orbital character, and effective mass and high-energy\nfeatures of the conduction band, this compact model will assist in the\ninvestigation and design of the electrical and optical properties of bulk\nmaterials, devices, and quantum confined heterostructures."
    },
    {
        "anchor": "Anomalous in-gap edge states in two-dimensional pseudospin-1 Dirac\n  insulators: Quantum materials that host a flat band, such as pseudospin-1 lattices and\nmagic-angle twisted bilayer graphene, can exhibit drastically new physical\nphenomena including unconventional superconductivity, orbital ferromagnetism,\nand Chern insulating behaviors. We report a surprising class of electronic\nin-gap edge states in pseudospin-1 materials without the conventional need of\nband-inversion topological phase transitions or introducing magnetism via an\nexternal magnetic type of interactions. In particular, we find that, in\ntwo-dimensional gapped (insulating) Dirac systems of massive spin-1\nquasiparticles, in-gap edge modes can emerge through only an {\\em electrostatic\npotential} applied to a finite domain. Associated with these unconventional\nedge modes are spontaneous formation of pronounced domain-wall spin textures,\nwhich exhibit the feature of out-of-plane spin-angular momentum locking on both\nsides of the domain boundary and are quite robust against boundary deformations\nand impurities despite a lack of an explicit topological origin. The in-gap\nmodes are formally three-component evanescent wave solutions, akin to the\nJackiw-Rebbi type of bound states. Such modes belong to a distinct class due to\nthe following physical reasons: three-component spinor wave function, unusual\nboundary conditions, and a shifted flat band induced by the external scalar\npotential. Not only is the finding of fundamental importance, but it also paves\nthe way for generating highly controllable in-gap edge states with emergent\nspin textures using the traditional semiconductor gate technology. Results are\nvalidated using analytic calculations of a continuum Dirac-Weyl model and\ntight-binding simulations of realistic materials through characterizations of\nlocal density of state spectra and resonant tunneling conductance.",
        "positive": "Growth of PbTe nanowires by Molecular Beam Epitaxy: Advances in quantum technology may come from the discovery of new materials\nsystems that improve the performance or allow for new functionality in\nelectronic devices. Lead telluride (PbTe) is a member of the group IV-VI\nmaterials family that has significant untapped potential for exploration. Due\nto its high electron mobility, strong spin-orbit coupling and ultrahigh\ndielectric constant it can host few-electron quantum dots and ballistic quantum\nwires with opportunities for control of electron spins and other quantum\ndegrees of freedom. Here, we report the fabrication of PbTe nanowires by\nmolecular beam epitaxy. We achieve defect-free single crystalline PbTe with\nlarge aspect ratios up to 50 suitable for quantum devices. Furthermore, by\nfabricating a single nanowire field effect transistor, we attain bipolar\ntransport, extract the bandgap and observe Fabry-Perot oscillations of\nconductance, a signature of quasiballistic transmission."
    },
    {
        "anchor": "Magnetization and spin gap in two-dimensional organic ferrimagnet\n  BIPNNBNO: A magnetization process in two-dimensional ferrimagnet BIPNNBNO is analyzed.\nThe compound consists of ferrimagnetic (1,1/2) chains coupled by two sorts of\nantiferromagnetic interactions. Whereas a behavior of the magnetization curve\nin higher magnetic fields can be understood within a process for the separate\nferrimagnetic chain, an appearance of the singlet plateau at lower fields is an\nexample of non-Lieb-Mattis type ferrimagnetism. By using the exact\ndiagonalization technique for a finite clusters of sizes 4x8 and 4x10 we show\nthat the interchain frustration coupling plays an essential role in\nstabilization of the singlet phase. These results are complemented by an\nanalysis of four cylindrically coupled ferrimagnetic (1,1/2) chains via an\nabelian bosonization technique and an effective theory based on the XXZ\nspin-1/2 Heisenberg model when the interchain interactions are sufficiently\nweak/strong, respectively.",
        "positive": "Optical Shubnikov - de Haas oscillations in 2D electron systems: We report on dynamic Shubnikov - de Haas (SdH) oscillations that are measured\nin the optical response, sub - terahertz transmittance of two-dimensional\nsystems, and reveal two distinct types of oscillation nodes: \"universal\" nodes\nat integer ratios of radiation and cyclotron frequencies and \"tunable\" nodes at\npositions sensitive to all parameters of the structure. The nodes in both real\nand imaginary parts of the measured complex transmittance are analyzed using a\ndynamic version of the static Lifshitz-Kosevich formula. These results\ndemonstrate that the node structure of the dynamic SdH oscillations provides an\nall-optical access to quantization- and interaction-induced renormalization\neffects, in addition to parameters one can obtain from the static SdH\noscillations."
    },
    {
        "anchor": "From semiclassical transport to quantum Hall effect under low-field\n  Landau quantization: The crossover from the semiclassical transport to quantum Hall effect is\nstudied by examining a two-dimensional electron system in an AlGaAs/GaAs\nheterostructure. By probing the magneto-oscillations, it is shown that the\nsemiclassical Shubnikov-de Haas (SdH) formulation can be valid even when the\nminima of the longitudinal resistivity approach zero. The extension of the\napplicable range of the SdH theory could be due to the damping effects\nresulting from disorder and temperature. Moreover, we observed plateau-plateau\ntransition like behavior with such an extension. From our study, it is\nimportant to include the positive magnetoresistance to refine the SdH theory.",
        "positive": "Field-Driven Evolution of Chiral Spin Textures in Thin Nanodisk of the\n  Helimagnets: The magnetic field-driven evolution of chiral spin textures in thin\nhelimagnet nanodisk with varied size are investigated by means of Monte Carlo\nsimulation. It is demonstrated that the complex spin texture may simply be\nregarded as the superposition of the edged state with in plane spin orientation\nperpendicular or parallel to the edge and the bulk state with the features\nsimilar to two-dimensional chiral magnetic films. With the increase of the\nexternal field, the proportion of the parallel spins of the edge state\nincreases, and the spin textures finally transfers into edged magnetic vortex.\nThe arrangement of skyrmions strongly depends on the disk size. In addition,\nthe uniaxial anisotropy and dipolar coupling in certain ranges are able to\nstabilize a special magnetic vortex with Skyrmionic core while the disk size is\ncomparable with the wavelength of helix state."
    },
    {
        "anchor": "Electronic and Spin-Orbit Properties of hBN Encapsulated Bilayer\n  Graphene: Van der Waals (vdW) heterostructures consisting of Bernal bilayer graphene\n(BLG) and hexagonal boron nitride (hBN) are investigated. By performing\nfirst-principles calculations we capture the essential BLG band structure\nfeatures for several stacking and encapsulation scenarios. A low-energy model\nHamiltonian, comprising orbital and spin-orbit coupling (SOC) terms, is\nemployed to reproduce the hBN-modified BLG dispersion, spin splittings, and\nspin expectation values. Most important, the hBN layers open an orbital gap in\nthe BLG spectrum, which can range from zero to tens of meV, depending on the\nprecise stacking arrangement of the individual atoms. Therefore, large local\nband gap variations may arise in experimentally relevant moir\\'{e} structures.\nMoreover, the SOC parameters are small (few to tens of $\\mu$eV), just as in\nbare BLG, but are markedly proximity modified by the hBN layers. Especially\nwhen BLG is encapsulated by monolayers of hBN, such that inversion symmetry is\nrestored, the orbital gap and spin splittings of the bands vanish. In addition,\nwe show that a transverse electric field mainly modifies the potential\ndifference between the graphene layers, which perfectly correlates with the\norbital gap for fields up to about 1~V/nm. Moreover, the layer-resolved Rashba\ncouplings are tunable by $\\sim 5~\\mu$eV per V/nm. Finally, by investigating\ntwisted BLG/hBN structures, with twist angles between 6$^{\\circ}$ --\n20$^{\\circ}$, we find that the global band gap increases linearly with the\ntwist angle. The extrapolated $0^{\\circ}$ band gap is about 23~meV and results\nroughly from the average of the stacking-dependent local band gaps. Our\ninvestigations give new insights into proximity spin physics of hBN/BLG\nheterostructures, which should be useful for interpreting experiments on\nextended as well as confined (quantum dot) systems.",
        "positive": "A new platform for topological quantum phenomena : Topological Insulator\n  states in thermoelectric Heusler-related ternary compounds: Topological insulators (TI) realize a novel state of quantum matter that are\ndistinguished by topological invariants of bulk band structure rather than\nspontaneously broken symmetries. A number of exotic quantum phenomena have been\npredicted to exist in multiply-connected geometries which require an enormous\namount of materials flexibility. We have extended our previous search for TI\nmaterials from binary (Bi2X3 series) to the thermoelectric ternary compounds.\nWe discover that the distorted LuPtSb is the first ternary compound harboring a\n3D topological insulator state. We also show that the half-Heusler LuPtSb-type\nseries is a natural platform that hosts a range of candidate compounds, alloys\nand artificial heterostructures (quantum-wells). We also discovered several\ndifferent paradigms of trivial and non-trivial topological ordering in this\nclass, including a metallic nontrivial topological state in YAuPb. Some of\nthese materials are grown (results will be reported separately)."
    },
    {
        "anchor": "Electroplating of conformal electrodes for vacuum nanogap tunnel\n  junction: In this study, we electroplate Cu electrode on Si substrate to realize a\nlarge-area vacuum nanogap for electron tunneling. We used cathode coating,\ncathode rotation, asymmetric current regime, and electrolyte temperature\nstabilization to obtain the regular geometry of the Cu electrode and reduce its\ninternal tension. Subsequently, internal tension was altered to achieve the\npredefined surface curvature (concave or convex). For 12-mm diameter Ag/Cu\nelectrode, we achieve the curvature of 40 nm/mm from the Ag side. Reduction of\nthe electrode diameter to 3 mm allowed curvature as low as of 2.5 nm/mm. It\nalso allowed fabrication of two conformal electrodes having a nanogap of less\nthan 5 nm wide, over the area of 7 mm2. Such electrodes can be used for\nefficient energy conversion and cooling in the mixed thermionic and\nthermotunneling regime.",
        "positive": "Massless Dirac fermions on a space-time lattice with a topologically\n  protected Dirac cone: The symmetries that protect massless Dirac fermions from a gap opening may\nbecome ineffective if the Dirac equation is discretized in space and time,\neither because of scattering between multiple Dirac cones in the Brillouin zone\n(fermion doubling) or because of singularities at zone boundaries. Here we\nintroduce an implementation of Dirac fermions on a space-time lattice that\nremoves both obstructions. The quasi-energy band structure has a tangent\ndispersion with a single Dirac cone that cannot be gapped without breaking both\ntime-reversal and chiral symmetries. We show that this topological protection\nis absent in the familiar single-cone discretization with a linear sawtooth\ndispersion, as a consequence of the fact that there the time-evolution operator\nis discontinuous at Brillouin zone boundaries."
    },
    {
        "anchor": "Influence of disorder on the perpendicular magnetoresistance of magnetic\n  multilayers: The effect of disorder on the perpendicular magnetoresistance of magnetic\nmultilayers is investigated theoretically. Various kinds of disorder are\nconsidered: (i) interface substitutional disorder and (ii) bulk disorder in the\nvarious layers and in the leads. The calculations are based upon the\nnon-equilibrium Green's function formalism, together with the recursion method\nfor calculating the real-space Green's function.",
        "positive": "Non-Markovian dynamics of a biased qubit coupled to a structured bath: A new analytical approach, beyond rotating wave approximation, based on\nunitary transformations and the non-Markovian master equation for the density\noperator, is applied to treat the biased spin boson model with a Lorentzian\nstructured bath for arbitrary detunings at zero temperature. Compared to zero\nbias, we find that the dynamics demonstrates two more damping oscillation\nfrequencies and one additional relaxation frequency for non-zero bias, where\none of the damping oscillation frequencies is a new effect. Analytical\nexpressions for the non-Markovian dynamics and the corresponding spectrum, the\nlocalized-delocalized transition point, the coherent-incoherent transition\npoint, the analytical ground energy, the renormalized tunneling factor and the\nsusceptibility are determined. The sum rule and the Shiba relation are checked\nin the coherent regime."
    },
    {
        "anchor": "Anomalous Transport in Sketched Nanostructures at the LaAlO3/SrTiO3\n  Interface: The oxide heterostructure LaAlO3/SrTiO3 supports a two-dimensional electron\nliquid with a variety of competing phases including magnetism,\nsuperconductivity and weak antilocalization due to Rashba spin-orbit coupling.\nFurther confinement of this 2D electron liquid to the quasi-one-dimensional\nregime can provide insight into the underlying physics of this system and\nreveal new behavior. Here we describe magnetotransport experiments on narrow\nLaAlO3/SrTiO3 structures created by a conductive atomic force microscope\nlithography technique. Four-terminal local transport measurements on\n~10-nm-wide Hall bar structures yield longitudinal resistances that are\ncomparable to the resistance quantum h/e2 and independent of the channel\nlength. Large nonlocal resistances (as large as 10^4 ohms) are observed in some\nbut not all structures with separations between current and voltage that are\nlarge compared to the 2D mean-free path. The nonlocal transport is strongly\nsuppressed by the onset of superconductivity below ~200 mK. The origin of these\nanomalous transport signatures is not understood, but may arise from coherent\ntransport defined by strong spin-orbit coupling and/or magnetic interactions.",
        "positive": "Spacetime magnetic hopfions: from internal excitations and braiding of\n  skyrmions: Spatial topology endows topological solitons, such as skyrmions and hopfions,\nwith fascinating dynamics. However, the temporal dimension has so far provided\na passive stage on which topological solitons evolve. Here we construct\nspacetime magnetic hopfions: magnetic textures in two spatial dimensions that\nwhen excited by a time-periodic drive develop spacetime topology. We uncover\ntwo complementary construction routes using skyrmions by braiding their center\nof mass position and by controlling their internal low-energy excitations.\nSpacetime magnetic hopfions can be realized in nanopatterned grids to braid\nskyrmions and in frustrated magnets under an applied AC electric field. Their\ntopological invariant, the spacetime Hopf index, can be tuned by the applied\nelectric field as demonstrated by our collective coordinate modeling and\nmicromagnetic simulations. The principles we have introduced to actively\ncontrol spacetime topology are not limited to magnetic solitons, opening\navenues to explore spacetime topology of general order parameters and fields."
    },
    {
        "anchor": "Controlling the direction of topological transport in a non-Hermitian\n  time-reversal symmetric Floquet ladder: We propose a one-dimensional Floquet ladder that possesses two distinct\ntopological transport channels with opposite directionality. The transport\nchannels occur due to a $\\mathbb Z_2$ non-Hermitian Floquet topological phase\nthat is protected by time-reversal symmetry. The signatures of this phase are\ntwo pairs of Kramers degenerate Floquet quasienergy bands that are separated by\nan imaginary gap. We discuss how the Floquet ladder can be implemented in a\nphotonic waveguide lattice and show that the direction of transport in the\nresulting waveguide structure can be externally controlled by focusing two\nlight beams into adjacent waveguides. The relative phase between the two light\nbeams selects which of the two transport channels is predominantly populated,\nwhile the angles of incidence of the two light beams determine which of the\ntransport channels is suppressed by non-Hermitian losses. We identify the\noptimal lattice parameters for the external control of transport and\ndemonstrate the robustness of this mechanism against disorder.",
        "positive": "Deconfined fractional electric charges in graphene at high magnetic\n  fields: The resistance at the charge neutral (Dirac) point was shown by Checkelsky et\nal in Phys. Rev. B 79, 115434 (2009) to diverge upon the application of a\nstrong magnetic field normal to graphene. We argue that this divergence is the\nsignature for a Kekule instability of graphene, which is induced by the\nmagnetic field. We show that the strong magnetic field does not remove the zero\nmodes that bind a fraction of the electron around vortices in the Kekule\ndimerization pattern, and that quenched disorder present in the system makes it\nenergetically possible to separate the fractional charges. These findings,\naltogether, indicate that graphene can sustain deconfined fractionalized\nelectrons."
    },
    {
        "anchor": "Electronic and optical gap renormalization in carbon nanotubes near a\n  metallic surface: Renormalization of quasiparticles and excitons in carbon nanotubes (CNTs)\nnear a metallic surface has been studied within a many-body formalism using an\nembedding approach newly implemented in the GW and Bethe-Salpeter methods. The\nquasiparticle bandgap renormalization in semiconducting CNTs is found to scale\nas -1/(2h_a), with h_a the apparent nanotube height, and it can exceed half an\neV. Also, the binding energy of excitons is reduced dramatically -by as much as\n75%- near the surface. Compensation between quasiparticle and excitonic effects\nresults in small changes in the optical gap. The important role played by the\nnanotube screening response in establishing these effects is emphasized and a\nsimple electrostatic model with no adjustable parameters explains the results\nof state-of-the-art calculations and generalizes them to a large variety of\nCNTs.",
        "positive": "Moir\u00e9 Superstructures in Marginally-Twisted NbSe$_2$ Bilayers: The creation of moir\\'e superlattices in twisted bilayers of two-dimensional\ncrystals has been utilised to engineer quantum material properties in graphene\nand transition metal dichalcogenide (TMD) semiconductors. Here, we examine the\nstructural relaxation and electronic properties in small-angle twisted bilayers\nof metallic NbSe$_2$. Reconstruction appears to be particularly strong for\nmisalignment angles $\\theta_P$ < 2.9$^o$ and $\\theta_{AP}$ < 1.2$^o$ for\nparallel (P) and antiparallel (AP) orientation of monolayers' unit cells,\nrespectively. Multiscale modelling reveals the formation of domains and domain\nwalls with distinct stacking, for which density functional theory (DFT)\ncalculations are used to map the shape of the bilayer Fermi surface and the\nrelative phase of the CDW order in adjacent layers. We find a significant\nmodulation of interlayer coupling across the moir\\'e superstructure and the\nexistence of preferred interlayer orientations of the CDW phase, necessitating\nthe nucleation of CDW discommensurations at superlattice domain walls."
    },
    {
        "anchor": "Mechanical Properties and Fracture Dynamics of Silicene Membranes: As graphene became one of the most important materials today, there is a\nrenewed interest on others similar structures. One example is silicene, the\nsilicon analogue of graphene. It share some the remarkable graphene properties,\nsuch as the Dirac cone, but presents some distinct ones, such as a pronounced\nstructural buckling. We have investigated, through density functional based\ntight-binding (DFTB), as well as reactive molecular dynamics (using ReaxFF),\nthe mechanical properties of suspended single-layer silicene. We calculated the\nelastic constants, analyzed the fracture patterns and edge reconstructions. We\nalso addressed the stress distributions, unbuckling mechanisms and the fracture\ndependence on the temperature. We analysed the differences due to distinct edge\nmorphologies, namely zigzag and armchair.",
        "positive": "Specular electron focusing between gate-defined quantum point contacts\n  in bilayer graphene: We report on multiterminal measurements in a ballistic bilayer graphene (BLG)\nchannel where multiple spin and valley-degenerate quantum point contacts (QPCs)\nare defined by electrostatic gating. By patterning QPCs of different shapes and\nalong different crystallographic directions, we study the effect of size\nquantization and trigonal warping on the transverse electron focusing (TEF)\nspectra. Our TEF spectra show eight clear peaks with comparable amplitude and\nweak signatures of quantum interference at the lowest temperature, indicating\nthat reflections at the gate-defined edges are specular and transport is phase\ncoherent. The temperature dependence of the scattering rate indicates that\nelectron-electron interactions play a dominant role in the charge relaxation\nprocess for electron doping and temperatures below 100 K. The achievement of\nspecular reflection, which is expected to preserve the pseudospin information\nof the electron jets, is promising for the realization of ballistic\ninterconnects for new valleytronic devices."
    },
    {
        "anchor": "Probing topological transitions in HgTe/CdTe quantum wells by\n  magneto-optical measurements: In two-dimensional topological insulators, such as inverted HgTe/CdTe quantum\nwells, helical quantum spin Hall (QSH) states persist even at finite magnetic\nfields below a critical magnetic field $B_\\mathrm{c}$, above which only quantum\nHall (QH) states can be found. Using linear-response theory, we theoretically\ninvestigate the magneto-optical properties of inverted HgTe/CdTe quantum wells,\nboth for infinite two-dimensional and finite-strip geometries, and possible\nsignatures of the transition between the QSH and QH regimes. In the absorption\nspectrum, several peaks arise due to non-equidistant Landau levels in both\nregimes. However, in the QSH regime, we find an additional absorption peak at\nlow energies in the finite-strip geometry. This peak arises due to the presence\nof edge states in this geometry and persists for any Fermi level in the QSH\nregime, while in the QH regime the peak vanishes if the Fermi level is situated\nin the bulk gap. Thus, by sweeping the gate voltage, it is possible to\nexperimentally distinguish between the QSH and QH regimes due to this\nsignature. Moreover, we investigate the effect of spin-orbit coupling and\nfinite temperature on this measurement scheme.",
        "positive": "Laser spectroscopy of individual quantum dots charged with a single hole: We characterize the positively charged exciton (X1+) in single InGaAs quantum\ndots using resonant laser spectroscopy. Three samples with different dopant\nspecies (Be or C as acceptors, Si as a donor) are compared. The p-doped samples\nexhibit larger inhomogeneous broadening (x3) and smaller absorption contrast\n(x10) than the n-doped sample. For X1+ in the Be-doped sample, a dot dependent\nnon-linear Fano effect is observed, demonstrating coupling to degenerate\ncontinuum states. However, for the C-doped sample the X1+ lineshape and\nsaturation broadening follows isolated atomic transition behaviour. This\nC-doped device structure is useful for single hole spin initialization,\nmanipulation, and measurement."
    },
    {
        "anchor": "Transport fluctuation relations in interacting quantum pumps: The understanding of out-of-equilibrium fluctuation relations in small open\nquantum systems has been a focal point of research in recent years. In\nparticular, for systems with adiabatic time-dependent driving, it was shown\nthat the fluctuation relations known from stationary systems do no longer apply\ndue the geometric nature of the pumping current response. However, the precise\nphysical interpretation of the corrected pumping fluctuation relations as well\nas the role of many-body interactions remained unexplored. Here, we study\nquantum systems with many-body interactions subject to slow time-dependent\ndriving, and show that fluctuation relations of the charge current can in\ngeneral not be formulated without taking into account the total energy current\nput into the system through the pumping process. Moreover, we show that this\ncorrection due to the input energy is nonzero only when Coulomb-interactions\nare present. Thus, fluctuation response relations offer an until now unrevealed\nopportunity to probe many-body correlations in quantum systems. We demonstrate\nour general findings at the concrete example of a single-level quantum dot\nmodel, and propose a scheme to measure the interaction-induced discrepancies\nfrom the stationary case.",
        "positive": "Magically strained bilayer graphene with flat bands: Twist bilayer graphenes with magical angle have nearly flat band, which\nbecome strongly correlated electron systems. Herein, we propose another system\nbased on strained bilayer graphene that have flat band at the intrinsic Fermi\nlevel. The top and bottom layers are uniaxially stretched along different\ndirections. When the strength and directions of the strain satisfy certain\ncondition, the periodical lattices of the two layers are commensurate to each\nother. The regions with AA, AB and BA stacking arrange in a triangular lattice.\nWith magical strain, the bands around the intrinsic Fermi level are nearly flat\nand have large gap from the other bands. This system could provide more\nfeasible platform for graphene-based integrated electronic system with\nsuperconductivity."
    },
    {
        "anchor": "Electron-Phonon Coupling in Two-Dimensional Silicene and Germanene: Following the work in graphene, we report a first-principles study of\nelectron-phonon coupling (EPC) in low-buckled (LB) monolayer silicene and\ngermanene. Despite of the similar honeycomb atomic arrangement and linear band\ndispersion, the EPC matrix-element squares of the $\\Gamma$-$E_g$ and K-$A_1$\nmodes in silicene are only about 50% of those in graphene. However, the smaller\nFermi velocity in silicene compensates this reduction by providing a larger\njoint electronic density of states near the Dirac point. We predict that Kohn\nanomalies associated with these two optical modes are significant in silicene.\nIn addition, the EPC-induced frequency shift and linewidth of the Raman-active\n$\\Gamma$-$E_g$ mode in silicene are calculated as a function of doping. The\nresults are comparable to those in graphene, indicating a similar non-adiabatic\ndynamical origin. In contrast, the EPC in germanene is found to be much\nreduced.",
        "positive": "Accurate six-band nearest-neighbor tight-binding model for the pi-bands\n  of bulk graphene and graphene nanoribbons: Accurate modeling of the pi-bands of armchair graphene nanoribbons (AGNRs)\nrequires correctly reproducing asymmetries in the bulk graphene bands as well\nas providing a realistic model for hydrogen passivation of the edge atoms. The\ncommonly used single-pz orbital approach fails on both these counts. To\novercome these failures we introduce a nearest-neighbor, three orbital per atom\np/d tight-binding model for graphene. The parameters of the model are fit to\nfirst-principles density-functional theory (DFT) - based calculations as well\nas to those based on the many-body Green's function and screened-exchange (GW)\nformalism, giving excellent agreement with the ab initio AGNR bands. We employ\nthis model to calculate the current-voltage characteristics of an AGNR MOSFET\nand the conductance of rough-edge AGNRs, finding significant differences versus\nthe single-pz model. These results show that an accurate bandstructure model is\nessential for predicting the performance of graphene-based nanodevices."
    },
    {
        "anchor": "New phenomena in CDW systems at small scales: The electrophysical properties of quasi-one-dimensional conductors with a\ncharge-density wave change qualitatively upon a decrease in their transverse\nsizes. A brief review of various finite-size effects and the present-day\nknowledge of their origin is presented.",
        "positive": "Mesoscopic fluctuations of conductance of a helical edge contaminated by\n  magnetic impurities: Elastic backscattering of electrons moving along the helical edge is\nprohibited by time-reversal symmetry (TRS). We demonstrate, however, that an\nensemble of magnetic impurities may cause TRS-preserving quasi-elastic\nbackscattering, resulting in interference effects in the conductance. The\ncharacteristic energy transferred in a backscattering event is suppressed due\nto the RKKY interaction of localized spins (the suppression is exponential in\nthe total number of magnetic impurities). We predict the statistics of\nconductance fluctuations to differ from those in the conventional case of a\none-dimensional system with quenched disorder."
    },
    {
        "anchor": "Micromagnetic evaluation of the dissipated heat in cylindrical magnetic\n  nanowires: Magnetic nanowires (NW) are promising candidates for heat generation under\nAC-field application due to their large shape anisotropy. They may be used for\ncatalysis, hyperthermia or water purification treatments. In the present work\nwe theoretically evaluate the heat dissipated by a single magnetic nanowire,\noriginated from the domain wall dynamics under the action of an AC-field. We\ncompare the Permalloy NWs (which demagnetize via the transverse wall\npropagation) with the Co fcc NWs whose reversal mode is via a vortex domain\nwall. The average hysteresis loop areas -which are proportional to the Specific\nAbsorption Rate (SAR)- as a function of the field frequency have a pronounced\nmaximum in the range 200MHz-1GHz. This maximum frequency is smaller in\nPermalloy than in Co and depends on the nanowire length. A simple model related\nto the nucleation and propagation time and domain wall velocity (higher for the\nvortex than for the transverse domain wall) is proposed to explain the\nnon-monotonic SAR dependence on the frequency.",
        "positive": "Kubo formula for dc conductivity: generalization to systems with\n  spin-orbit coupling: We revise the Kubo formula for the electric dc conductivity in the presence\nof spin-orbit coupling (SOC). We discover that each velocity operator that\nenters this formula differs from $\\partial H/\\partial \\boldsymbol p$, where $H$\nis the Hamiltonian and $\\boldsymbol p$ is the canonical momentum. Moreover, we\nfind an additional contribution to the Hall dc conductivity from noncommuting\ncoordinates that is missing in the conventional Kubo-Streda formula. This\ncontribution originates from the \"electron-positron\" matrix elements of the\nvelocity and position operators. We argue that the widely used Rashba model\ndoes in fact provide a finite anomalous Hall dc conductivity in the metallic\nregime (in the noncrossing approximation) if SOC-corrections to the velocity\nand position operators are properly taken into account. While we focus on the\nresponse of the charge current to the electric field, linear response theories\nof other SOC-related effects should be modified similarly."
    },
    {
        "anchor": "Majorana fermions in pinned vortices: Exploiting the peculiar properties of proximity-induced superconductivity on\nthe surface of a topological insulator, we propose a device which allows the\ncreation of a Majorana fermion inside the core of a pinned Abrikosov vortex.\nThe relevant Bogolyubov-de Gennes equations are studied analytically. We\ndemonstrate that in this system the zero-energy Majorana fermion state is\nseparated by a large energy gap, of the order of the zero-temperature\nsuperconducting gap $\\Delta$, from a band of single-particle non-topological\nexcitations. In other words, the Majorana fermion remains robust against\nthermal fluctuations, as long as the temperature remains substantially lower\nthan the critical superconducting temperature. Experimentally, the Majorana\nstate may be detected by measuring the tunneling differential conductance at\nthe center of the Abrikosov vortex. In such an experiment, the Majorana state\nmanifests itself as a zero-bias anomaly separated by a gap, of the order of\n$\\Delta$, from the contributions of the nontopological excitations.",
        "positive": "A composite electrodynamic mechanism to reconcile spatiotemporally\n  resolved exciton transport in quantum dot superlattices: Quantum dot (QD) solids are promising optoelectronic materials; further\nadvancing their device functionality depends on understanding their energy\ntransport mechanisms. The commonly invoked near-field F\\\"orster resonance\nenergy transfer (FRET) theory often underestimates the exciton hopping rate in\nQD solids, yet no consensus exists on the underlying cause. In response, we use\ntime-resolved ultrafast stimulated emission depletion (TRUSTED) microscopy, an\nultrafast transformation of stimulated emission depletion (STED) microscopy to\nspatiotemporally resolve exciton diffusion in tellurium-doped\nCdSe-core/CdS-shell QD superlattices. We measure the concomitant time-resolved\nexciton energy decay due to excitons sampling a heterogeneous energetic\nlandscape within the superlattice. The heterogeneity is quantified by\nsingle-particle emission spectroscopy. This powerful multimodal set of\nobservables provides sufficient constraints on a kinetic Monte Carlo simulation\nof exciton transport to elucidate a composite transport mechanism that includes\nboth near-field FRET and previously-neglected far-field emission/reabsorption\ncontributions. Uncovering this mechanism offers a much-needed unified framework\nin which to characterize transport in QD solids and additional principles for\ndevice design."
    },
    {
        "anchor": "Classical electrons in laterally coupled diatomic 2D artificial molecule: Structural properties of a finite number ($N = 2 - 20$) of point charges\n(classical electrons) confined laterally in a two-dimensional two-minima\npotential are calculated as a function of the distance ($d$) between the\nminima. The particles are confined by identical parabolic potentials and repel\neach other through a Coulomb potential. Both ground state and metastable\nelectron configurations are discussed. At zero distance previous results of\nother calculations and experiments are reproduced. Discontinuous transitions\nfrom one configuration to another as a function of $d$ are observed for $N = 6,\n8, 11, 16, 17, 18, 19$.",
        "positive": "Evidence for the formation of nanoprecipitates with magnetically\n  disordered regions in bulk $\\mathrm{Ni}_{50}\\mathrm{Mn}_{45}\\mathrm{In}_{5}$\n  Heusler alloys: Shell ferromagnetism is a new functional property of certain Heusler alloys\nwhich has been recently observed in\n$\\mathrm{Ni}_{50}\\mathrm{Mn}_{45}\\mathrm{In}_{5}$. We report the results of a\ncomparative study of the magnetic microstructure of bulk\n$\\mathrm{Ni}_{50}\\mathrm{Mn}_{45}\\mathrm{In}_{5}$ Heusler alloys using\nmagnetometry, synchrotron x-ray diffraction, and magnetic small-angle neutron\nscattering (SANS). By combining unpolarized and spin-polarized SANS (POLARIS)\nwe demonstrate that a number of important conclusions regarding the mesoscopic\nspin structure can be made. In particular, the analysis of the magnetic neutron\ndata suggests that nanoprecipitates with an effective ferromagnetic component\nform in an antiferromagnetic matrix on field annealing at $700 \\, \\mathrm{K}$.\nThese particles represent sources of perturbation, which seem to give rise to\nmagnetically disordered regions in the vicinity of the particle-matrix\ninterface. Analysis of the spin-flip SANS cross section via the computation of\nthe correlation function yields a value of $\\sim 55 \\, \\mathrm{nm}$ for the\nparticle size and $\\sim 20 \\, \\mathrm{nm}$ for the size of the spin-canted\nregion."
    },
    {
        "anchor": "Electric Field Tunable Band Gap in Commensurate Twisted Bilayer Graphene: Bernal bilayer graphene exhibits a band gap that is tunable through the\ninfrared with an electric field. We show that sublattice odd commensurate\ntwisted bilayer graphene (C-TBG) exhibits a band gap that is tunable through\nthe terahertz with an electric field. We show that from the perspective of\nterahertz optics the sublattice odd and even forms of C-TBG are \"inflated\"\nversions of Bernal and AA stacked bilayer graphene respectively with energy\nscales reduced by a factor of 110 for the 21.79 degree commensurate unit cell.\nThis lower energy scale is accompanied by a correspondingly smaller gate\nvoltage, which means that the strong-field regime is more easily accessible\nthan in the Bernal case. Finally, we show that the interlayer coherence energy\nis a directly accessible experimental quantity through the position of a\npower-law divergence in the optical conductivity.",
        "positive": "Modification of the charge and magnetic order of a low dimensional\n  ferromagnet by molecule-surface bonding: The ability to design and control the spin and charge order of low\ndimensional materials on the molecular scale offers an intriguing pathway\ntowards the miniaturization of spintronic technology towards the nanometer\nscale. In this work, we focus on the adsorption induced modifications of the\nmagnetic and electronic properties of a low dimensional ferromagnetic surface\nalloy after the adsorption of the prototypical organic molecule\nperylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA). For this metal-organic\ninterface, we observe the formation of a localized $\\sigma$-like bond between\nthe functional molecular groups and the surface alloy atoms. This strong\nchemical bonding coincides with a lifting of the characteristic surface alloy\nband structure and a reduction of the magnitude of the local magnetic moments\nof the Dy atoms by 18%. We attribute both findings to a mixing of\nspin-degenerate molecular states with spin-split states of the Dy-Ag surface\nalloy via the sigma-like bonds between PTCDA and the Dy surface alloy atoms.\nOur findings clearly demonstrate the potential of tailored molecule-surface\nsigma-bonds to control not only the electronic but also the magnetic order of\nlow dimensional materials."
    },
    {
        "anchor": "Coherent Branched Flow in a Two-Dimensional Electron Gas: Semiconductor nanostructures based on two dimensional electron gases (2DEGs)\nhave the potential to provide new approaches to sensing, information\nprocessing, and quantum computation. Much is known about electron transport in\n2DEG nanostructures and many remarkable phenomena have been discovered (e.g.\nweak localization, quantum chaos, universal conductance fluctuations)1,2 - yet\na fundamental aspect of these devices, namely how electrons move through them,\nhas never been clarified. Important details about the actual pattern of\nelectron flow are not specified by statistical measures such as the mean free\npath. Scanned probe microscope (SPM) measurements allow spatial investigations\nof nanostructures, and it has recently become possible to directly image\nelectron flow through 2DEG devices using newly developed SPM techniques3-13.\nHere we present SPM images of electron flow from a quantum point contact (QPC)\nwhich show unexpected dynamical channeling - the electron flow forms\npersistent, narrow, branching channels rather than smoothly spreading fans.\nTheoretical study of this flow, including electron scattering by impurities and\ndonor atoms, shows that the channels are not due to deep valleys in the\npotential, but rather are caused by the indirect cumulative effect of small\nangle scattering. Surprisingly, the channels are decorated by interference\nfringes well beyond where the simplest thermal averaging arguments suggest they\nshould be found. These findings may have important implications for 2DEG\nphysics and for the design of future nanostructure devices.",
        "positive": "Spin-filtered Edge States with an Electrically Tunable Gap in a\n  Two-Dimensional Topological Crystalline Insulator: Three-dimensional topological crystalline insulators were recently predicted\nand observed in the SnTe class of IV-VI semiconductors, which host metallic\nsurface states protected by crystal symmetries. In this work, we study thin\nfilms of these materials and expose their potential for device applications. We\ndemonstrate that thin films of SnTe and Pb(1-x)Sn(x)Se(Te) grown along the\n(001) direction are topologically nontrivial in a wide range of film thickness\nand carry conducting spin-filtered edge states that are protected by the (001)\nmirror symmetry via a topological invariant. Application of an electric field\nperpendicular to the film will break the mirror symmetry and generate a band\ngap in these edge states. This functionality motivates us to propose a novel\ntopological transistor device, in which charge and spin transport are maximally\nentangled and simultaneously controlled by an electric field. The high on/off\noperation speed and coupling of spin and charge in such a device may lead to\nelectronic and spintronic applications for topological crystalline insulators."
    },
    {
        "anchor": "Terahertz photoresponse of a quantum Hall edge-channel diode: The Teraherz (THz) photoresponse of a two-dimensional electron gas in the\nquantum Hall regime is investigated. We use a sample structure which is\ntopologically equivalent to a Corbino geometry combined with a cross-gate\ntechnique. This quasi-Corbino geometry allows us to directly investigate the\nTHz-induced transport between adjacent edge-states, thus avoiding bulk effects.\nWe find a pronounced photo voltage at zero applied bias, which rapidly\ndecreases when an external current bias is applied. The photo voltage and its\ndependence on the bias current can be described using the model of an\nilluminated photodiode, resulting from the reconstruction of the Landau bands\nat the sample edge. Using the sample as a detector in a Fourier transform\nspectrometer setup, we find a resonant response from which we extract a reduced\neffective cyclotron mass. The findings support a non-bolometric mechanism of\nthe induced photo voltage and the proposed edge-channel diode model.",
        "positive": "Theory of the Fabry-Perot Quantum Hall Interferometer: We analyze interference phenomena in the quantum-Hall analog of the\nFabry-Perot interferometer, exploring the roles of the Aharonov-Bohm effect,\nCoulomb interactions, and fractional statistics on the oscillations of the\nresistance as one varies the magnetic field B and/or the voltage V_G applied to\na side gate. Coulomb interactions couple the interfering edge mode to localized\nquasiparticle states in the bulk, whose occupation is quantized in integer\nvalues. For the integer quantum Hall effect, if the bulk-edge coupling is\nabsent, the resistance exhibits an Aharonov-Bohm (AB) periodicity, where the\nphase is equal to the number of quanta of magnetic flux enclosed by a specified\ninterferometer area. When bulk-edge coupling is present, the actual area of the\ninterferometer oscillates as function of B and V_G, with a combination of a\nsmooth variation and abrupt jumps due to changes in the number of\nquasi-particles in the bulk of the interferometer. This modulates the\nAharonov-Bohm phase and gives rise to additional periodicities in the\nresistance. In the limit of strong interactions, the amplitude of the AB\noscillations becomes negligible, and one sees only the new \"Coulomb-dominated\"\n(CD) periodicity. In the limits where either the AB or the CD periodicities\ndominate, a color map of resistance will show a series of parallel stripes in\nthe B-V_G plane, but the two cases show different stripe spacings and slopes of\nopposite signs. At intermediate coupling, one sees a superposition of the two\npatterns. We discuss the dependence of the interference intensities on\nparameters including the temperature and the backscattering strengths of the\nindividual constrictions. We also discuss how results are modified in a\nfractional quantized Hall system, and the extent to which the interferometer\nmay demonstrate the fractional statistics of the quasiparticles."
    },
    {
        "anchor": "Topological and non-topological features of generalized\n  Su-Schrieffer-Heeger models: The (one-dimensional) Su-Schrieffer-Heeger Hamiltonian, augmented by\nspin-orbit coupling and longer-range hopping, is studied at half filling for an\neven number of sites. The ground-state phase diagram depends sensitively on the\nsymmetry of the model. Charge-conjugation (particle-hole) symmetry is conserved\nif hopping is only allowed between the two sublattices of even and odd sites.\nIn this case (of BDI symmetry) we find a variety of topologically non-trivial\nphases, characterized by different numbers of edge states (or, equivalently,\ndifferent quantized Zak phases). The transitions between these phases are\nclearly signalled by the entanglement entropy. Charge-conjugation symmetry is\nbroken if hopping within the sublattices is admitted (driving the system into\nthe AI symmetry class). We study specifically next-nearest-neighbor hopping\nwith amplitudes $t_a$ and $t_b$ for the $A$ and $B$ sublattices, respectively.\nFor $t_a=t_b$ parity is conserved, and also the quantized Zak phases remain\nunchanged in the gapped regions of the phase diagram. However, metallic patches\nappear due to the overlap between conduction and valence bands in some regions\nof parameter space. The case of alternating next-nearest neighbor hopping,\n$t_a=-t_b$, is also remarkable, as it breaks both charge-conjugation $C$ and\nparity $P$ but conserves the product $CP$. Both the Zak phase and the\nentanglement spectrum still provide relevant information, in particular about\nthe broken parity. Thus the Zak phase for small values of $t_a$ measures the\ndisparity between bond strengths on $A$ and $B$ sublattices, in close analogy\nto the proportionality between the Zak phase and the polarization in the case\nof the related Aubry-Andr\\'e model.",
        "positive": "3/2 Fractional Quantum Hall Plateau in Confined Two-Dimensional Electron\n  Gas: Even-denominator fractional quantum Hall (FQH) states, such as 5/2 and 7/2,\nhave been well known in a two-dimensional electron gas (2DEG) for decades and\nare still investigated as candidates of non-Abelian statistics. In this paper,\nwe present the observation of a 3/2 FQH plateau in a single-layer 2DEG with\nlateral confinement at a bulk filling factor of 5/3. The 3/2 FQH plateau is\nquantized at (h/e^2 )/(3/2) within 0.02%, and can survive up to 300 mK. This\neven-denominator FQH plateau may imply intriguing edge structure and excitation\nin FQH system with lateral confinement. The observations in this work\ndemonstrate that understanding the effect of the lateral confinement on the\nmany-body system is critical in the pursuit of important theoretical proposals\ninvolving edge physics, such as the demonstration of non-Abelian statistics and\nthe realization of braiding for fault-tolerant quantum computation."
    },
    {
        "anchor": "Renormalization group study of transport through a superconducting\n  junction of multiple one-dimensional quantum wires: We investigate transport properties of a superconducting junction of many ($N\n\\ge 2$) one-dimensional quantum wires. We include the effectofelectron-electron\ninteraction within the one-dimensional quantum wire using a weak interaction\nrenormalization group procedure. Due to the proximity effect, transport across\nthe junction occurs via direct tunneling as well as via the crossed Andreev\nchannel. We find that the fixed point structure of this system is far more rich\nthan the fixed point structure of a normal metal$-$superconductor junction ($N\n= 1$), where we only have two fixed points - the fully insulating fixed point\nor the Andreev fixed point. Even a two wire (N=2)system with a superconducting\njunction i.e. a normalmetal$-$superconductor$-$normal metal structure, has\nnon-trivialfixed points with intermediate transmissions and reflections. We\nalso include electron-electron interaction induced back-scattering in the\nquantum wires in our study and hence obtain non-Luttinger liquid behaviour. It\nis interesting to note that {\\textsl{(a)}} effects due to inclusion of\nelectron-electron interaction induced back-scattering in the wire, and\n{\\textsl{(b)}} competition between the charge transport via the electron and\nhole channels across the junction, give rise to a non-monotonic behavior of\nconductance as a functionof temperature. We also find that transport across the\njunction depends on two independent interaction parameters. The first one is\ndue to the usual correlations coming from Friedel oscillations for spin-full\nelectrons giving rise to the well-known interaction parameter (${{\\alpha =\n(g_2-2g_1)/2 \\pi \\hbar v_F}}$). The second one arises due to the scattering\ninduced by the proximity of the superconductor and is given by(${{\\alpha^\\prime\n= (g_2 + g_1)/2 \\pi \\hbar v_F}}$).",
        "positive": "Interpolation formula for the reflection coefficient distribution of\n  absorbing chaotic cavities in the presence of time reversal symmetry: We propose an interpolation formula for the distribution of the reflection\ncoefficient in the presence of time reversal symmetry for chaotic cavities with\nabsorption. This is done assuming a similar functional form as that when time\nreversal invariance is absent. The interpolation formula reduces to the\nanalytical expressions for the strong and weak absorption limits. Our proposal\nis compared to the quite complicated exact result existing in the literature."
    },
    {
        "anchor": "Zitterbewegung of electrons in carbon nanotubes created by laser pulses: We describe a possibility of creating non-stationary electron wave packets in\nzigzag carbon nanotubes (CNT) illuminated by short laser pulses. After\ndisappearance of the pulse the packet experiences the trembling motion\n(Zitterbewegung, ZB). The band structure of CNT is calculated using the\ntight-binding approximation generalized for the presence of radiation.\nEmploying realistic pulse and CNT parameters we obtain the ZB oscillations with\ninter-band frequencies corresponding to specific pairs of energy bands. A\nchoice of optimal parameters is presented in order to observe the phenomenon of\nZB experimentally. The use of Gaussian wave packets to trigger the electron\nZitterbewegung, as used in the literature, is critically reexamined.",
        "positive": "Effective orbital ordering in multiwell optical lattices with fermionic\n  atoms: We consider the behavior of Fermi atoms on optical superlattices with\ntwo-well structure of each node. Fermions on such lattices serve as an analog\nsimulator of Fermi type Hamiltonian. We derive a mapping between fermion\nquantum ordering in the optical superlattices and the spin-orbital physics\ndeveloped for degenerate $d$-electron compounds. The appropriate effective\nspin-orbital model appears to be the modification of the Kugel-Khomskii\nHamiltonian. We show how different ground states of this Hamiltonian correspond\nto particular spin-pseudospin arrangement patterns of fermions on the lattice.\nThe dependence of fermion arrangement on phases of complex hopping amplitudes\nis illustrated."
    },
    {
        "anchor": "Dramatic increase in the thermal boundary conductance and radiation\n  limit from a Nonequilibrium Landauer Approach: Thermal boundary conductance (TBC) is critical in many thermal and energy\napplications. A decades-old puzzle has been that many of the measured TBCs,\nsuch as those well characterized across Al/Si and ZnO/GaN interfaces,\nsignificantly exceed theoretical results or even the absolute upper limit\ncalled the ``radiation limit\", suggesting the failure of the theory. Here, we\nidentify that for high-transmission interfaces, the commonly assumed phonon\nlocal thermal equilibrium adjacent to the interface fails, and the measurable\nphonon temperatures are not their emission temperature. We hence develop a\n``nonequilibrium Landauer approach\" and define the unique ``dressed\" and\n``intrinsic\" TBCs. Combining our approach even with a simple diffuse mismatch\nmodel (DMM) nearly doubles the theoretical TBCs across the Al/Si and ZnO/GaN\ninterfaces, and the theoretical results agree with experiments for the first\ntime. The radiation limit is also redefined and found to increase over 100\\%\nover the original radiation limit, and it can now well bound all the\nexperimental data.",
        "positive": "Multiterminal transport spectroscopy of subgap states in\n  Coulomb-blockaded superconductors: Subgap states are responsible for the low-bias transport features of hybrid\nsuperconducting--semiconducting devices. Here, we analyze the local and\nnonlocal differential conductance of Coulomb-blockaded multiterminal\nsuperconducting islands that host subgap states with different spatial\nstructures. The emerging patterns of their transport spectroscopy are used to\ncharacterize the possible topological nature of these devices and offer the\npossibility of controlling their transport properties. We develop a\nnext-to-leading order master equation to describe the multiterminal transport\nin superconductors with both strong Coulomb interactions and multiple subgap\nstates, coupled with metallic leads. We show that the nonlocal differential\nconductance characterizes the spatial extension of the subgap states and\nsignals the presence of degenerate bound states with a finite support on\ndifferent parts of the device. Additionally, it displays sharp sign changes as\na function of the induced charge of the superconductor, signaling energy\ncrossings among its lowest excited states."
    },
    {
        "anchor": "Quantum Hall ferromagnetic phases in the Landau level N=0 of a graphene\n  bilayer: In a Bernal-stacked graphene bilayer, an electronic state in Landau level $%\nN=0$ is described by its guiding-center index $X$ (in the Landau gauge) and by\nits valley, spin, and orbital indices $\\xi =\\pm K,\\sigma =\\pm 1,$ and $%\nn=0,1.$ When Coulomb interaction is taken into account, the chiral\ntwo-dimensional electron gas (C2DEG) in this system can support a variety of\nquantum Hall ferromagnetic (QHF)\\ ground states where the spins and/or valley\npseudospins and/or orbital pseudospins collectively align in space. In this\nwork, we give a comprehensive account of the phase diagram of the C2DEG at\ninteger filling factors $\\nu \\in [-3,3] $ in Landau level N=0 when an\nelectrical potential difference $\\Delta_{B}$ between the two layers is varied.\nWe consider states with or without layer, spin, or orbital coherence. For each\nphase, we discuss the behavior of the transport gap as a function of\n$\\Delta_{B},$ the spectrum of collective excitations and the optical absorption\ndue to orbital pseudospin-wave modes. We also study the effect of an external\nin-plane electric field on a coherent state that has both valley and spin\ncoherence and show that it is possible, in such a state, to control the spin\npolarization by varying the strength of the external in-plane electric field.",
        "positive": "Manipulation of Ferromagnets via the Spin-Selective Optical Stark Effect: We investigate the non-resonant all-optical switching of magnetization. We\ntreat the inverse Faraday effect (IFE) theoretically in terms of the\nspin-selective optical Stark effect for linearly or circularly polarized light.\nIn the dilute magnetic semiconductors (Ga,Mn)As, strong laser pulses below the\nband gap induce effective magnetic fields of several teslas in a direction\nwhich depends on the magnetization and light wave vectors. Our theory\ndemonstrates that the polarized light catalyzes the angular momentum transfer\nbetween lattice and the magnetization."
    },
    {
        "anchor": "Tracking electron pathways with magnetic field: Aperiodic Aharonov-Bohm\n  oscillations in coherent transport through a periodic array of quantum dots: We study resonant tunneling through a periodic square array of quantum dots\nsandwiched between modulation-doped quantum wells. If a magnetic field is\napplied parallel to the quantum dot plane, the tunneling current exhibits a\nhighly complex Aharonov-Bohm oscillation pattern due to the interference of\nmultiple pathways traversed by a tunneling electron. Individual pathways\nassociated with conductance beats can be enumerated by sweeping the magnetic\nfield at various tilt angles. Remarkably, Aharonov-Bohm oscillations are\naperiodic unless the magnetic field slope relative to the quantum dot lattice\naxes is a rational number.",
        "positive": "Charge-carrier mobility in hydrogen-terminated diamond field-effect\n  transistors: Diamond field-effect transistors (FETs) have potential applications in power\nelectronics and high-output high-frequency amplifications. In such\napplications, high charge-carrier mobility is desirable for a reduced loss and\nhigh-speed operation. We have recently fabricated diamond FETs with a\nhexagonal-boron-nitride gate dielectric and observed a high mobility above 300\ncm$^{2}$V$^{-1}$s$^{-1}$. In this study, we examine which scattering mechanism\nlimits the mobility of our FETs through theoretical calculations. Our\ncalculations reveal that the dominant carrier scattering is caused by surface\ncharged impurities with the density of $\\approx$1$\\times10^{12}$ cm$^{-2}$, and\nsuggest a possible increase in mobility over 1000 cm$^{2}$V$^{-1}$s$^{-1}$ by\nreducing the impurities."
    },
    {
        "anchor": "Electron energy spectrum and oscillator strengths of quantum transitions\n  in double quantum ring nanostructure driven by electric field: The effect of homogeneous electric field on the energy spectrum, wave\nfunctions of electron and oscillator strengths of intra-band quantum\ntransitions in a double cylindrical quantum ring (GaAs/Al$_{x}$Ga$_{1-x}$As) is\nstudied within the approximations of effective mass and rectangular potentials.\nThe calculations are performed using the method of expansion of quasiparticle\nwave function over a complete set of cylindrical wave functions obtained as\nexact solutions of Schr\\\"odinger equation for an electron in a nanostructure\nwithout electric field. It is shown that the electric field essentially affects\nthe electron localization in the rings of a nanostructure. Herein, the electron\nenergies and oscillator strengths of intra-band quantum transitions\nnon-monotonously depend on the intensity of electric field.",
        "positive": "Mode- and size-dependent Landau-Lifshitz damping in magnetic\n  nanostructures: Evidence for non-local damping: We demonstrate a strong dependence of the effective damping on the nanomagnet\nsize and the particular spin-wave mode that can be explained by the theory of\nintralayer transverse-spin-pumping. The effective Landau-Lifshitz damping is\nmeasured optically in individual, isolated nanomagnets as small as 100 nm. The\nmeasurements are accomplished by use of a novel heterodyne magneto-optical\nmicrowave microscope with unprecedented sensitivity. Experimental data reveal\nmultiple standing spin-wave modes that we identify by use of micromagnetic\nmodeling as having either localized or delocalized character, described\ngenerically as end- and center-modes. The damping parameter of the two modes\ndepends on both the size of the nanomagnet as well as the particular spin-wave\nmode that is excited, with values that are enhanced by as much as 40% relative\nto that measured for an extended film. Contrary to expectations based on the ad\nhoc consideration of lithography-induced edge damage, the damping for the\nend-mode decreases as the size of the nanomagnet decreases. The data agree with\nthe theory for damping caused by the flow of intralayer transverse\nspin-currents driven by the magnetization curvature. These results have serious\nimplications for the performance of nanoscale spintronic devices such as\nspin-torque-transfer magnetic random access memory."
    },
    {
        "anchor": "Double quantum dot in a quantum dash: optical properties: We study the optical properties of highly anisotropic quantum dot structures\n(quantum dashes) characterized by the presence of two trapping centers located\nalong the structure. Such a system can exhibit some of the properties\ncharacteristic for double quantum dots. We show that sub- and super-radiant\nstates can form for certain quantum dash geometries, which is manifested by a\npronounced transfer of intensity between spectral lines, accompanied by the\nappearance of strong electron-hole correlations. We also compare exciton\nabsorption spectra and polarization properties of a system with a single and\ndouble trapping center and show how the geometry of multiple trapping centers\ninfluences the optical properties of the system. We show that for a broad range\nof trapping geometries the relative absorption intensity of the ground state is\nlarger than that of the lowest excited states, contrary to the quantum dash\nsystems characterized by a single trapping center. Thus, optical properties of\nthese structures are determined by fine details of their morphology.",
        "positive": "Electron transport in multiterminal networks of Majorana bound states: We investigate electron transport through multiterminal networks hosting\nMajorana bound states (MBS) in the framework of full counting statistics (FCS).\nIn particular, we apply our general results to T-shaped junctions of two\nMajorana nanowires. When the wires are in the topologically nontrivial regime,\nthree MBS are localized near the outer ends of the wires, while one MBS is\nlocalized near the crossing point, and when the lengths of the wires are finite\nadjacent MBS can overlap. We propose a combination of current and\ncross-correlation measurements to reveal the predicted coupling of four\nMajoranas in a topological T~junction. Interestingly, we show that the\nelementary transport processes at the central lead are different compared to\nthe outer leads, giving rise to characteristic non-local signatures in\nelectronic transport. We find quantitative agreement between our analytical\nmodel and numerical simulations of a tight-binding model. Using the numerical\nsimulations, we discuss the effect of weak disorder on the current and the\ncross-correlation functions."
    },
    {
        "anchor": "Robustness of spin coherence of the exciton bound to neutral donor\n  states in multilayer system: We address the temperature influence on the precessional motion of electron\nspins under transverse magnetic field, studied in a GaAs/AlGaAs triple quantum\nwells, using pump-probe Kerr rotation. In the presence of an applied in-plane\nmagnetic field the TRKR measurements show the robustness of carrier's spin\npolarization against temperature which can be easily traced in an extended\nrange up to 250 K. By tuning the pump-probe wavelength to the exciton bound to\na neutral donor transition, we observed a remarkably long-lasting spin\ncoherence (with dephasing time T2* > 14 ns) limited by the spin hopping process\nand exchange interaction between the donor sites as well as the ensemble spread\nof g-factor. The temperature dependent spin dephasing time revealed a double\nlinear dependence due to the different relaxation mechanisms active at\nrespective temperature ranges. We observed that the increase of sample\ntemperature from 5 K to 250 K, leads to a strong T2* reduction by almost\n98%/97% for the excitation wavelengths of 823/821 nm. Furthermore, we noticed\nthat the temperature increase not only causes the reduction of spin lifetime\nbut can also lead to the variation of electron g-factor. Additionally, the spin\ndynamics was studied through the dependencies on the applied magnetic field and\noptical pump power.",
        "positive": "Electronic model of a volcano-shaped size dependence in CO oxidation by\n  gold nanoparticles: The theoretical model of a volcano-type size dependence of extraordinary\ncatalytic activity of gold nanoparticles in CO oxidation is proposed based on\nthe electronic theory of catalysis, the jellium model of metal clusters and the\nd-band model of formation bonds in transition metals. The kinetics of the\ngeneral mechanism of CO oxidation reaction catalyzed by gold nanoparticles\nthrough dissociative adsorption of oxygen molecules and interaction with CO\nmolecules from the gas-phase is considered by introducing electronic steps into\n3-step mechanism of the reaction, corresponding to transitions between weak and\nstrong chemisorbed states of intermediates. By introducing the exponential\ndependences of the fractions of weak and strong chemisorbed intermediates (O,\nCO2) on the size dependent Fermi level of the metal cluster with respect to\nantibonding energy levels of the intermediates, a volcano-type dependence of\nreaction rate on the size of gold nanoparticles is obtained. The dependence of\nthe reaction rate upon the supports is taken into account by introducing the\nadditional energy term into the Fermi level of the metal catalyst."
    },
    {
        "anchor": "Spin-dependent electron transport along hairpin-like DNA molecules: The chirality-induced spin selectivity (CISS), demonstrated in diverse chiral\nmolecules by numerous experimental and theoretical groups, has been attracting\nextensive and ongoing interest in recent years. As the secondary structure of\nDNA, the charge transfer along DNA hairpins has been widely studied for more\nthan two decades, finding that DNA hairpins exhibit spin-related effects as\nreported in recent experiments. Here, we propose a setup to demonstrate\ndirectly the CISS effect in DNA hairpins contacted by two nonmagnetic leads at\nboth ends of the stem. Our results indicate that DNA hairpins present\npronounced CISS effect and the spin polarization could be enhanced by using\nconducting molecules as the loop. In particular, DNA hairpins show several\nintriguing features, which are different from other chiral molecules. First,\nthe local spin currents can flow circularly and assemble into a number of\nvortex clusters when the electron energy locates in the left/right electronic\nband of the stem. The chirality of vortex clusters in each band is the same and\nwill be reversed by switching the electron energy from the left band to the\nright one, inducing the sign reversal of the spin polarization. Interestingly,\nthe local spin currents can be greater than the corresponding spin component of\nthe source-drain current. Second, both the conductance and the spin\npolarization can increase with molecular length as well as dephasing strength,\ncontrary to the physical intuition that the transmission ability of molecular\nwires should be poorer when suffering from stronger scattering. Third, we\nunveil the optimal contact configuration of efficient electron transport and\nthat of the CISS effect, which are distinct from each other and can be\ncontrolled by dephasing strength. The underlying physical mechanism is\nillustrated.",
        "positive": "The Josephson light-emitting diode: We consider an optical quantum dot where an electron level and a hole level\nare coupled to respective superconducting leads. We find that electrons and\nholes recombine producing photons at discrete energies as well as a continuous\ntail. Further, the spectral lines directly probe the induced superconducting\ncorrelations on the dot. At energies close to the applied bias voltage eV, a\nparameter range exists, where radiation proceeds in pairwise emission of\npolarization correlated photons. At energies close to 2eV, emitted photons are\nassociated with Cooper pair transfer and are reminiscent of Josephson\nradiation. We discuss how to probe the coherence of these photons in a SQUID\ngeometry via single photon interference."
    },
    {
        "anchor": "Interplay between non-Hermiticity and non-Abelian gauge potential in\n  topological photonics: Topological phases in spinless non-Hermitian models have been widely studied\nboth theoretically and experimentally in some artificial materials using\nphotonics, phononics and magnon. In this work, we investigate the interplay\nbetween non-Hermitian loss and gain and non-Abelian gauge potential realized in\na two-component superconducting circuit. In our model, the non-Hermiticity\nalong only gives rise to trivial gain and loss to the states; while the\nnon-Abelian gauge along gives rise to flying butterfly spectra and associated\nedge modes, which in photonics can be directly measured by the intensity of\nphotons at the boundaries. These two terms do not commute, and their interplay\ncan give rise to several intriguing non-Hermitian phases, including the fully\ngapped quantum spin Hall (QSH) phase, gapless QSH phase, trivial gapped phase\nand gapless metallic phase. The bulk-edge correspondence is absent and we find\nthat during the closing of energy gap in the gapped QSH phase, the system\nenters the gapless QSH phase regime which still supports two\ncounter-propagating edge modes. We have also unveiled the intriguing role of\nnon-Hermiticity on the chiral symmetry and time-reversal symmetry of the\nHermitian models, which can be applied to other physical models.",
        "positive": "Chiral Cavity Quantum Electrodynamics: Cavity quantum electrodynamics, which explores the granularity of light by\ncoupling a resonator to a nonlinear emitter, has played a foundational role in\nthe development of modern quantum information science and technology. In\nparallel, the field of condensed matter physics has been revolutionized by the\ndiscovery of underlying topological robustness in the face of disorder, often\narising from the breaking of time-reversal symmetry, as in the case of the\nquantum Hall effect. In this work, we explore for the first time cavity quantum\nelectrodynamics of a transmon qubit in the topological vacuum of a\nHarper-Hofstadter topological lattice. To achieve this, we assemble a square\nlattice of niobium superconducting resonators and break time-reversal symmetry\nby introducing ferrimagnets before coupling the system to a single transmon\nqubit. We spectroscopically resolve the individual bulk and edge modes of this\nlattice, detect vacuum-stimulated Rabi oscillations between the excited\ntransmon and each mode, and thereby measure the synthetic-vacuum-induced Lamb\nshift of the transmon. Finally, we demonstrate the ability to employ the\ntransmon to count individual photons within each mode of the topological band\nstructure. This work opens the field of chiral quantum optics experiment,\nsuggesting new routes to topological many-body physics and offering unique\napproaches to backscatter-resilient quantum communication."
    },
    {
        "anchor": "Theoretical Prediction of Two-Dimensional Functionalized MXene Nitrides\n  as Topological Insulators: Recently, two-dimensional (2D) transition metal carbides and nitrides,\nnamely, MXenes have attracted lots of attention for electronic and energy\nstorage applications. Due to a large spin-orbit coupling (SOC) and the\nexistence of a Dirac-like band at the Fermi energy, it has been theoretically\nproposed that some of the MXenes will be topological insulators (TIs). Up to\nnow, all of the predicted TI MXenes belong to transition metal carbides, whose\ntransition metal atom is W, Mo or Cr. Here, on the basis of first-principles\nand Z2 index calculations, we demonstrate that some of the MXene nitrides can\nalso be TIs. We find that Ti3N2F2 is a 2D TI, whereas Zr3N2F2 is a semimetal\nwith nontrivial band topology and can be turned into a 2D TI when the lattice\nis stretched. We also find that the tensile strain can convert Hf3N2F2\nsemiconductor into a 2D TI. Since Ti is one of the mostly used transition metal\nelement in the synthesized MXenes, we expect that our prediction can advance\nthe future application of MXenes as TI devices.",
        "positive": "Giant thermopower and power factor in magic angle twisted bilayer\n  graphene at low temperature: The in-plane phonon-drag thermopower $S^g$, diffusion thermopower $S^d$ and\nthe power factor $PF$ are theoretically investigated in twisted bilayer\ngraphene (tBLG) as a function of twist angle $\\theta$, temperature $T$ and\nelectron density $n_s$ in the region of low $T$ (1-20 K). As $\\theta$\napproaches magic angle $\\theta_m$, the $S^g$ and $S^d$ are found to be strongly\nenhanced, which is manifestation of great suppression of Fermi velocity\n${\\nu_F}^*$ of electrons in moire flat band near $\\theta_m$. This enhancement\ndecreases with increasing $\\theta$ and $T$. In the Bloch- Gruneisen (BG)\nregime, it is found that $S^g \\sim {\\nu_F}^{* -2}$, $T^3$ and ${n_s}^{-1/2}$.\nAs $T$ increases, the exponent $\\delta$ in $S^g \\sim T^\\delta$, changes from 3\nto nearly zero and a maximum $S^g$ value of $\\sim$ 10 mV/K at $\\sim$ 20 K is\nestimated. $S^g$ is larger (smaller) for smaller $n_s$ in low (high)\ntemperature region. On the other hand, $S^d$, taken to be governed by Mott\nformula, $\\sim {\\nu_F}^{* -1}$, $T$ and ${n_s}^{-1/2}$ and $S^d<<S^g$ for $T >\n\\sim$ 2 K. The power factor $PF$ is also found to be strongly $\\theta$\ndependent and very much enhanced. Consequently, possibility of a giant figure\nof merit is discussed.In tBLG, $\\theta$ acts as a strong tuning parameter of\nboth $S^g$ and $S^d$ and $PF$ in addition to $T$ and $n_s$. Our results are\nqualitatively compared with the measured out-of-plane thermopower in tBLG."
    },
    {
        "anchor": "Taylor series of Landauer conductance: In this paper, we propose a method to calculate the exact Taylor series of\nthe scattering matrix in general multiterminal tight-binding systems to\narbitrary order N, which allows us to find the Taylor expansion of Landauer\nconductance in mesoscopic systems. The method is based on the recursive\nscattering matrix method (RSMM) that permits us to find the scattering matrix\nof a system from the scattering matrices of its subsystems. Following ideas of\nautomatic differentiation, we determine expressions for the sum, product,\ninverse, and diagonalization of a matrix Taylor expansion, and use them into\nthe RSMM to find Taylor series of scattering matrices. The method is validated\nby obtaining the transmission function of atomic chains with site defects and\ngraphene nanoconstrictions. Finally, an analysis of convergence radius and\nerror estimations of these Taylor expansions is presented.",
        "positive": "Neel probability and spin correlations in some nonmagnetic and\n  nondegenerate states of hexanuclear antiferromagnetic ring Fe6: Application\n  of algebraic combinatorics to finite Heisenberg spin systems: The spin correlations \\omega^z_r, r=1,2,3, and the probability p_N$ of\nfinding a system in the Neel state for the antiferromagnetic ring Fe(III)6 (the\nso-called `small ferric wheel') are calculated. States with magnetization M=0,\ntotal spin 0<=S<=15 and labeled by two (out of four) one-dimensional\nirreducible representations (irreps) of the point symmetry group D_6 are taken\ninto account. This choice follows from importance of these irreps in analyzing\nlow-lying states in each S-multiplet. Taking into account the Clebsch--Gordan\ncoefficients for coupling total spins of sublattices (SA=SB=15/2) the global\nNeel probability p*_N can be determined. Dependencies of these quantities on\nstate energy (per bond and in the units of exchange integral J) and the total\nspin S are analyzed. Providing we have determined p_N(S) etc. for other\nantiferromagnetic rings (Fe10, for instance) we could try to approximate\nresults for the largest synthesized ferric wheel Fe18. Since thermodynamic\nproperties of Fe6 have been investigated recently, in the present\nconsiderations they are not discussed, but only used to verify obtained values\nof eigenenergies. Numerical results re calculated with high precision using two\nmain tools: (i) thorough analysis of symmetry properties including methods of\nalgebraic combinatorics and (ii) multiple precision arithmetic library GMP. The\nsystem considered yields more than 45 thousands basic states (the so-called\nIsing configurations), but application of the method proposed reduces this\nproblem to 20-dimensional eigenproblem for the ground state (S=0). The largest\neigenproblem has to be solved for S=4; its dimension is 60. These two facts\n(high precision and small resultant eigenproblems) confirm efficiency and\nusefulness of such an approach, so it is briefly discussed here."
    },
    {
        "anchor": "Non-Hermitian skin modes induced by on-site dissipations and chiral\n  tunneling effect: In this paper, we study the conditions under which on-site dissipations can\ninduce non-Hermitian skin modes in non-Hermitian systems. When the original\nHermitian Hamiltonian has spinless time-reversal symmetry, it is impossible to\nhave skin modes; on the other hand, if the Hermitian Hamiltonian has spinful\ntime-reversal symmetry, skin modes can be induced by on-site dissipations under\ncertain circumstance. As a concrete example, we employ the Rice-Mele model to\nillustrate our results. Furthermore, we predict that the skin modes can be\ndetected by the chiral tunneling effect, that is, the tunneling favors the\ndirection where the skin modes are localized. Our work reveals a no-go theorem\nfor the emergence of skin modes, and paves the way for searching for quantum\nsystems with skin modes and studying their novel physical responses.",
        "positive": "Feedback enhanced Dyakonov-Shur instability in Graphene-FET: Graphene devices are known to have the potential to operate THz signals. In\nparticular, graphene field-effect transistors have been proposed as devices to\nhost plasmonic instabilities in the THz realm; for instance, Dyakonov-Shur\ninstability which relies upon dc excitation. In this work, starting from a\nhydrodynamical description of the charge carriers, we extend the transmission\nline description of graphene field-effect transistors to a scheme with a\npositive feedback loop, also considering the effects of delay, which leads to\nthe transcendental transfer function with terms of the form $e^{as}{\\rm\nsech}^k(s)/s$. Applying the conditions for the excitation of Dyakonov-Shur\ninstability, we report an enhanced voltage gain in the linear regime that is\ncorroborated by our simulations of the nonlinear hydrodynamic model for the\ncharge carriers. This translates to both greater saturation amplitude -- often\nup to 50% increase -- and fastest growth rate of the self-oscillations. Thus,\nwe bring forth a prospective concept for the realization of a THz oscillator\nsuitable for future plasmonic circuitry."
    },
    {
        "anchor": "Wave function description of conductance mapping for quantum Hall\n  electron interferometer: Scanning gate microscopy of quantum point contacts (QPC) in the integer\nquantum Hall regime is considered in terms of the scattering wave functions\nwith a finite-difference implementation of the quantum transmitting boundary\napproach. Conductance ($G$) maps for a clean QPC as well as for a system\nincluding an antidot within the constriction are evaluated. The step-like\nlocally flat $G$ maps for clean QPCs turn into circular resonances that are\nreentrant in external magnetic field when the antidot is introduced to the\nconstriction.\n  The current circulation around the antidot and the spacing of the resonances\nat the magnetic field scale react to the probe approaching the QPC. The\ncalculated $G$ maps with a rigid but soft antidot potential reproduce the\nfeatures detected recently in the electron interferometer [F. Martins et al.\nNature Sci. Rep. 3, 1416 (2013)].",
        "positive": "Structural Evolution and Optoelectronic Applications of Multilayer\n  Silicene: Despite the recent progress on two-dimensional multilayer materials (2DMM)\nwith weak interlayer interactions, the investigation on 2DMM with strong\ninterlayer interactions is far from its sufficiency. Here we report on\nfirst-principles calculations that clarify the structural evolution and\noptoelectronic properties of such a 2DMM, multilayer silicene. With our newly\ndeveloped global optimization algorithm, we discover the existence of rich\ndynamically stable multilayer silicene phases, the stability of which is\nclosely related to the extent of sp3 hybridization that can be evaluated by the\naverage bonds and effective bond angles. The stable Si(111) surface structures\nare obtained when the silicene thickness gets up to four, showing the critical\nthickness for the structural evolution. We also find that the multilayer\nsilicene with pi-bonded surfaces present outstanding optoelectronic properties\nfor the solar cells and optical fiber communications due to the incorporation\nof sp2-type bonds in the sp3-type bonds dominated system. This study is helpful\nto complete the picture of structure and related property evolution of 2DMM\nwith strong interlayer interactions."
    },
    {
        "anchor": "Dipolar coupled core-shell perpendicular shape anisotropy MTJ with\n  enhanced write speed and reduced cross-talk: The concept of Perpendicular Shape-Anisotropy Spin-Transfer-Torque Magnetic\nRandom-Access Memory tackles the downsize scalability limit of conventional\nultrathin magnetic tunnel junctions (MTJ) below sub-20 nm technological nodes.\nThis concept uses a thicker storage layer with a vertical aspect ratio,\nenhancing the thermal stability factor thanks to the favorable contribution of\nthe shape anisotropy. However, the increased aspect ratio comes with an\nincrease in switching time under applied voltage and the cross-over to\nnon-uniform reversal mechanism at higher aspect ratio, limiting the gain in\nscalability. Additionally, the larger volume of the magnetic cell significantly\nincreases the stray field acting on the neighboring devices compared to thin\nMTJs. In this work, we propose the use of a dipolar-coupled core-shell system\nas a storage layer. This improves both bottlenecks, as predicted by\nmicromagnetic simulations for magnetisation reversal, and a macrospin model to\nestimate the stray field in a dense array.",
        "positive": "Dissociation of two-dimensional excitons in monolayer WSe2: Two-dimensional (2D) semiconducting materials are promising building blocks\nfor optoelectronic applications, many of which require efficient dissociation\nof excitons into free electrons and holes. However, the strongly bound excitons\narising from the enhanced Coulomb interaction in these monolayers suppresses\nthe creation of free carriers. Here, we probe and identify the main exciton\ndissociation mechanism through time- and spectrally-resolved photocurrent\nmeasurements in a monolayer WSe2 p-n junction. We find that under static\nin-plane electric field, excitons dissociate at a rate corresponding to the one\npredicted for the tunnel ionization of 2D Wannier-Mott excitons. This study is\nessential for the understanding of the optoelectronic photoresponse in of 2D\nsemiconductors, and offers design rules for the realization of efficient\nphotodetectors, valley-dependent optoelectronics and novel quantum coherent\nphases."
    },
    {
        "anchor": "Enhanced spin-orbit scattering length in narrow Al_xGa_{1-x}N/GaN wires: The magnetotransport in a set of identical parallel AlGaN/GaN quantum wire\nstructures was investigated. The width of the wires was ranging between 1110 nm\nand 340 nm. For all sets of wires clear Shubnikov--de Haas oscillations are\nobserved. We find that the electron concentration and mobility is approximately\nthe same for all wires, confirming that the electron gas in the AlGaN/GaN\nheterostructure is not deteriorated by the fabrication procedure of the wire\nstructures. For the wider quantum wires the weak antilocalization effect is\nclearly observed, indicating the presence of spin-orbit coupling. For narrow\nquantum wires with an effective electrical width below 250 nm the weak\nantilocalization effect is suppressed. By comparing the experimental data to a\ntheoretical model for quasi one-dimensional structures we come to the\nconclusion that the spin-orbit scattering length is enhanced in narrow wires.",
        "positive": "Non-invasive detection of molecular bonds in quantum dots: We performed charge detection on a lateral triple quantum dot with star-like\ngeometry. The setup allows us to interpret the results in terms of two double\ndots with one common dot. One double dot features weak tunnel coupling and can\nbe understood with atom-like electronic states, the other one is strongly\ncoupled forming molecule-like states. In nonlinear measurements we identified\npatterns that can be analyzed in terms of the symmetry of tunneling rates.\nThose patterns strongly depend on the strength of interdot tunnel coupling and\nare completely different for atomic- or molecule-like coupled quantum dots\nallowing the non-invasive detection of molecular bonds."
    },
    {
        "anchor": "Spin-Hall Effect in Two-Dimensional Electron Systems with Rashba\n  Spin-Orbit Coupling and Disorder: Using the four-terminal Landauer-B\\\"{u}ttiker formula and Green's function\napproach, we calculate numerically the spin-Hall conductance in a\ntwo-dimensional junction system with the Rashba spin-orbit (SO) coupling and\ndisorder. We find that the spin-Hall conductance can be much greater or smaller\nthan the universal value $e/8\\pi$, depending on the magnitude of the SO\ncoupling, the electron Fermi energy and the disorder strength. The spin-Hall\nconductance does not vanish with increasing sample size for a wide range of\ndisorder strength. Our numerical calculation reveals that a nonzero SO coupling\ncan induce electron delocalization for disorder strength smaller than a\ncritical value, and the nonvanishing spin-Hall effect appears mainly in the\nmetallic regime.",
        "positive": "Experimental Phase Diagram of a One-Dimensional Topological\n  Superconductor: Topological superconductors can host Majorana quasiparticles which supersede\nthe fermion/boson dichotomy and offer a pathway to fault tolerant quantum\ncomputation. In one-dimensional systems zero-energy Majorana states are bound\nto the ends of the topologically superconducting regions. An experimental\nsignature of a Majorana bound state is a conductance peak at zero source-drain\nvoltage bias in a tunneling experiment. Here, we identify the bulk topological\nphase in a semiconductor nanowire coupled to a conventional superconductor. We\nmap out its phase diagram through the dependence of zero-bias peak on the\nchemical potential and magnetic field. Our findings are consistent with\ncalculations for a finite-length topological nanowire. Knowledge of the phase\ndiagram makes it possible to predictably tune nanowire segments in and out of\nthe topological phase, thus controlling the positions and couplings of multiple\nMajorana bound states. This ability is a prerequisite for Majorana braiding, an\nexperiment in which Majorana quantum states are exchanged in order to both\ndemonstrate their non-abelian character and realize topological quantum bits."
    },
    {
        "anchor": "Temperature dependent transport in suspended graphene: The resistivity of ultra-clean suspended graphene is strongly temperature\ndependent for 5K<T<240K. At T~5K transport is near-ballistic in a device of\n~2um dimension and a mobility ~170,000 cm^2/Vs. At large carrier density,\nn>0.5*10^11 cm^-2, the resistivity increases with increasing T and is linear\nabove 50K, suggesting carrier scattering from acoustic phonons. At T=240K the\nmobility is ~120,000 cm^2/Vs, higher than in any known semiconductor. At the\ncharge neutral point we observe a non-universal conductivity that decreases\nwith decreasing T, consistent with a density inhomogeneity <10^8 cm^-2.",
        "positive": "Quantum percolation in granular metals: Theory of quantum corrections to conductivity of granular metal films is\ndeveloped for the realistic case of large randomly distributed tunnel\nconductances. Quantum fluctuations of intergrain voltages (at energies E much\nbelow bare charging energy scale E_C) suppress the mean conductance \\bar{g}(E)\nmuch stronger than its standard deviation \\sigma(E). At sufficiently low\nenergies E_* any distribution becomes broad, with \\sigma(E_*) ~ \\bar{g}(E_*),\nleading to strong local fluctuations of the tunneling density of states.\nPercolative nature of metal-insulator transition is established by combination\nof analytic and numerical analysis of the matrix renormalization group\nequations."
    },
    {
        "anchor": "A new relation between the hot electron power loss and acoustic phonon\n  limited mobility in Bloch-Gr\u00fcneisen regime: Expressions for the electron power loss F(T) and mobility {\\mu}_p due to\nacoustic phonon scattering are given in the Bloch-Gr\\\"uneisen (BG) regime for\nthree- and two- dimensional electron gas in semiconductors and Dirac-fermions.\nWe obtain a simple relation F(T) {\\mu}_p = {\\eta}ev_s^2, where {\\eta} (~1) is a\nconstant, e is the electron charge and v_s is acoustic phonon velocity. It is\nfound to be independent of temperature and electron concentration. This\nrelation is applied to GaAs heterojucntions and graphene, to obtain {\\mu}_p\nfrom the measured F(T). We propose that, using this relation, the measurements\nof F(T), in BG regime, which depends exclusively upon acoustic phonons\ncoupling, could serve as a tool to determine the low temperature {\\mu}_p, which\nis otherwise difficult to measure due to the contributions from disorders",
        "positive": "Thermal interferometry of anyons in spin liquids: Aharonov-Bohm interferometry is the most direct probe of anyonic statistics\nin the quantum Hall effect. The technique involves oscillations of the electric\ncurrent as a function of the magnetic field and is not applicable to Kitaev\nspin liquids and other systems without charged quasiparticles. Here, we\nestablish a novel protocol, involving heat transport, for revealing fractional\nstatistics even in the absence of charged excitations, as is the case in\nquantum spin liquids. Specifically, we demonstrate that heat transport in\nKitaev spin liquids through two distinct interferometer geometries, Fabry-Perot\nand Mach-Zehnder, exhibits drastically different behaviors. Therefore, we\npropose the use of heat transport interferometry as a probe of anyonic\nstatistics in charge insulators."
    },
    {
        "anchor": "Gaffnian holonomy through the coherent state method: We analyze the effect of exchanging quasiholes described by Gaffnian quantum\nHall trial state wave functions. This exchange is carried out via adiabatic\ntransport using the recently developed coherent state Ansatz. We argue that our\nAnsatz is justified if the Gaffnian parent Hamiltonian has a charge gap, even\nthough it is gapless to neutral excitations, and may therefore properly\ndescribe the adiabatic transport of Gaffnian quasiholes. For nonunitary states\nsuch as the Gaffnian, the result of adiabatic transport cannot agree with the\nmonodromies of the conformal block wave functions, and may or may not lead to\nwell-defined anyon statistics. Using the coherent state Ansatz, we find two\nunitary solutions for the statistics, one of which agrees with the statistics\nof the non-Abelian spin-singlet state by Ardonne and Schoutens.",
        "positive": "Splitting of the monolayer out-of-plane A'1 Raman mode in few-layer WS2: We present Raman measurements of mono- and few-layer WS2. We study the\nmonolayer A'1 mode around 420 cm(-1) and its evolution with the number of\nlayers. We show that with increasing layer number there is an increasing number\nof possible vibrational patterns for the out-of-plane Raman mode: in N-layer\nWS2 there are N Gamma-point phonons evolving from the A'1 monolayer mode. For\nan excitation energy close to resonance with the excitonic transition energy we\nwere able to observe all of these N components, irrespective of their Raman\nactivity. Density functional theory calculations support the experimental\nfindings and make it possible to attribute the modes to their respective\nsymmetries. The findings described here are of general importance for all other\nphonon modes in WS2 and other layered transition metal dichalcogenide systems\nin the few layer regime."
    },
    {
        "anchor": "Topological design of graphene: Topological defects (e.g. pentagons, heptagons and pentagon-heptagon pairs)\nhave been widely observed in large scale graphene and have been recognized to\nplay important roles in tailoring the mechanical and physical properties of\ntwo-dimensional materials in general. Thanks to intensive studies over the past\nfew years, optimizing properties of graphene through topological design has\nbecome a new and promising direction of research. In this chapter, we review\nsome of the recent advances in experimental, computational and theoretical\nstudies on the effects of topological defects on mechanical and physical\nproperties of graphene and applications of topologically designed graphene. The\ndiscussions cover out-of-plane effects, inverse problems of designing\ndistributions of topological defects that make a graphene sheet conform to a\ntargeted three-dimensional surface, grain boundary engineering for graphene\nstrength, curved graphene for toughness enhancement and applications in\nengineering energy materials, multifunctional materials and interactions with\nbiological systems. Despite the rapid developments in experiments and\nsimulations, our understanding on the relations between topological defects and\nmechanical and physical properties of graphene and other 2D materials is still\nin its infancy. The intention here is to draw the attention of the research\ncommunity to some of the open questions in this field.",
        "positive": "Entangled end states with fractionalized spin projection in a\n  time-reversal-invariant topological superconducting wire: We study the ground state and low-energy subgap excitations of a finite wire\nof a time-reversal-invariant topological superconductor (TRITOPS) with\nspin-orbit coupling. We solve the problem analytically for a long chain of a\nspecific one-dimensional lattice model in the electron-hole symmetric\nconfiguration and numerically for other cases of the same model. We present\nresults for the spin density of excitations in long chains with an odd number\nof particles. The total spin projection along the axis of the spin-orbit\ncoupling $S_z= \\pm 1/2$ is distributed with fractions $\\pm 1/4$ localized at\nboth ends, and shows even-odd alternation along the sites of the chain. We\ncalculate the localization length of these excitations and find that it can be\nwell approximated by a simple analytical expression. We show that the energy\n$E$ of the lowest subgap excitations of the finite chain defines tunneling and\nentanglement between end states.We discuss the effect of a Zeeman coupling\n$\\Delta_Z$ on one of the ends of the chain only. For $\\Delta_Z<E$, the energy\ndifference of excitations with opposite spin orientation is $\\Delta_Z/2$,\nconsistent with a spin projection $\\pm 1/4$. We argue that these physical\nfeatures are not model dependent and can be experimentally observed in TRITOPS\nwires under appropriate conditions."
    },
    {
        "anchor": "Chiral edge modes in evolutionary game theory: a kagome network of\n  rock-paper-scissors: We theoretically demonstrate the realization of a chiral edge mode in a\nsystem beyond natural science. Specifically, we elucidate that a kagome network\nof rock-paper-scissors (K-RPS) hosts a chiral edge mode of the population\ndensity which is protected by the non-trivial topology in the bulk. The\nemergence of the chiral edge mode is demonstrated by numerically solving the\nLotka-Volterra (LV) equation. This numerical result can be intuitively\nunderstood in terms of cyclic motion of a single RPS cycle which is analogues\nto the cyclotron motion of fermions. Furthermore, we point out that a\nlinearized LV equation is mathematically equivalent to the Schr\\\"odinger\nequation describing quantum systems. This equivalence allows us to clarify the\ntopological origin of the chiral edge mode in the K-RPS; a non-zero Chern\nnumber of the payoff matrix induces the chiral edge mode of the population\ndensity, which exemplifies the bulk-edge correspondence in two-dimensional\nsystems described by evolutionary game theory.",
        "positive": "Skyrmion bound state and dynamics in an antiferromagnetic bilayer\n  racetrack: We investigate the dynamics of two skyrmions lying in distinct layers of an\nantiferromagnetic bilayer system, consisting of nanostripes with the shape of\nracetracks. The top and bottom nanostripes are separated by a height offset and\nthey are coupled through a ferromagnetic exchange, allowing the interaction\nbetween the skyrmions from both layers. Depending on the distance between the\nskyrmions they attract each other sufficiently to achieve a bound state. We\nalso analyze their dynamics when an electric current is applied in a unique\nlayer and we determine how the bound-state nucleation depends on the current\ndensity and vertical distance between the skyrmions. Finally, we analyzed the\nrobustness of the bound states by considering two situations: 1) a system\nconstituted by clean or homogeneous antiferromagnetic racetracks; 2) a system\nin which randomly distributed magnetic impurities in both layers are included\nin the system."
    },
    {
        "anchor": "Dynamical and Reversible Control of Topological Spin Textures: Recent observations of topological spin textures brought spintronics one step\ncloser to new magnetic memories. Nevertheless, the existence of Skyrmions, as\nwell as their stabilization, require very specific intrinsic magnetic\nproperties which are usually fixed in magnets. Here we address the possibility\nto dynamically control their intrinsic magnetic interactions by varying the\nstrength of a high-frequency laser field. It is shown that drastic changes can\nbe induced in the antiferromagnetic exchange interactions and the latter can\neven be reversed to become ferromagnetic, provided the direct exchange is\nalready non-negligible in equilibrium as predicted, for example, in Si doped\nwith C, Sn, or Pb adatoms. In the presence of Dzyaloshinskii-Moriya\ninteractions, this enables us to tune features of ferromagnetic Skyrmions such\nas their radius, making them easier to stabilize. Alternatively, such\ntopological spin textures can occur in frustrated triangular lattices. Then, we\ndemonstrate that a high-frequency laser field can induce dynamical frustration\nin antiferromagnets, where the degree of frustration can subsequently be tuned\nsuitably to drive the material toward a Skyrmionic phase.",
        "positive": "Scale-Invariant Dissipationless Chiral Transport in Magnetic Topological\n  Insulators beyond the Two-Dimensional Limit: We investigate the quantum anomalous Hall Effect (QAHE) and related chiral\ntransport in the millimeter-size (Cr0.12Bi0.26Sb0.62)2Te3 films. With high\nsample quality and robust magnetism at low temperatures, the quantized Hall\nconductance of e2/h is found to persist even when the film thickness is beyond\nthe two-dimensional (2D) hybridization limit. Meanwhile, the Chern\ninsulator-featured chiral edge conduction is manifested by the non-local\ntransport measurements. In contrast to the 2D hybridized thin film, an\nadditional weakly field-dependent longitudinal resistance is observed in the 10\nquintuple-layer film, suggesting the influence of the film thickness on the\ndissipative edge channel in the QAHE regime. The extension of QAHE into the\nthree-dimensional thickness region addresses the universality of this quantum\ntransport phenomenon and motivates the exploration of new QAHE phases with\ntunable Chern numbers. In addition, the observation of the scale-invariant\ndissipationless chiral propagation on a macroscopic scale makes a major stride\ntowards ideal low-power interconnect applications."
    },
    {
        "anchor": "Bulk Inversion Asymmetry effects on the band structure of zincblende\n  heterostructures in an 8-band Effective Mass Approximation model: We have developed an 8-band Effective Mass Approximation model that describes\nthe zero field spin splitting in the band structure of zincblende\nheterostructures due to bulk inversion asymmetry (BIA). We have verified that\nour finite difference Hamiltonian transforms in almost all situations according\nto the true $D_{2d}$ or $C_{2v}$ symmetry of [001] heterostructures. This makes\nit a computationally efficient tool for the accurate description of the band\nstructure of heterostructures for spintronics. We first compute the band\nstructure for an AlSb/GaSb/AlSb quantum well (QW), which presents only BIA, and\ndelineate its effects. We then use our model to find the band structure of an\nAlSb/InAs/GaSb/AlSb QW and the relative contribution of structural and bulk\ninversion asymmetry to the spin splitting. We clarify statements about the\nimportance of these contributions and conclude that, even for our small gap QW,\nBIA needs to be taken into account for the proper description of the band\nstructure.",
        "positive": "Feasibility of terahertz lasing in optically pumped epitaxial multiple\n  graphene layer structures: A multiple-graphene-layer (MGL) structure with a stack of GLs and a highly\nconducting bottom GL on SiC substrate pumped by optical radiation is considered\nas an active region of terahertz (THz) and far infrared (FIR) lasers with\nexternal metal mirrors. The dynamic conductivity of the MGL structure is\ncalculated as a function of the signal frequency, the number of GLs, and the\noptical pumping intensity. The utilization of optically pumped MGL structures\nmight provide the achievement of lasing with the frequencies of about 1 THz at\nroom temperature due to a high efficiency."
    },
    {
        "anchor": "Macroscale non-local transfer of superconducting signatures to a\n  ferromagnet in a cavity: Cavity spintronics recently heralded non-local magnonic signal transfer\nbetween magnetic samples. Here we show that by including superconductors in the\ncavity, we can make use of these principles to bring composite\nsuperconductor--ferromagnet systems to the macroscale. We analyze how a\nsuperconductor's a.c. conductivity influences the spin dynamics of a spatially\nseparated magnet, and we discuss the potential impact on spintronic\napplications.",
        "positive": "A small mode volume tunable microcavity: development and\n  characterization: We report the realization of a spatial and spectrally tunable air-gap\nFabry-Perot type microcavity of high finesse and cubic-wavelength-scale mode\nvolume. These properties are attractive in the fields of opto-mechanics,\nquantum sensing and foremost cavity quantum electrodymanics. The major design\nfeature is a miniaturized concave mirror with atomically smooth surface and\nradius of curvature as low as 10 micrometer produced by CO2 laser ablation of\nfused silica. We demonstrate excellent mode-matching of a focussed laser beam\nto the microcavity mode and confirm from the frequencies of the resonator modes\nthat the effective optical radius matches the physical radius. With these small\nradii, we demonstrate sub-wavelength beam waists. We also show that the\nmicrocavity is sufficiently rigid for practical applications: in a cryostat at\n4K, the root-mean-square microcavity length fluctuations are below 5 pm."
    },
    {
        "anchor": "Aharonov-Bohm oscillations in p-type GaAs quantum rings: We have explored phase coherent transport of holes in two p-type GaAs quantum\nrings with orbital radii 420 nm and 160 nm fabricated with AFM oxidation\nlithography. Highly visible Aharonov-Bohm (AB) oscillations are measured in\nboth rings, with an amplitude of the oscillations exceeding 10% of the total\nresistance in the case of the ring with a radius of 160 nm. Beside the h/e\noscillations, we resolve the contributions from higher harmonics of the AB\noscillations. The observation of a local resistance minimum at B=0 T in both\nrings is a signature of the destructive interference of the holes' spins. We\nshow that this minimum is related to the minimum in the h/2e oscillations.",
        "positive": "Giant Anisotropic Magneto-Resistance in ferromagnetic atomic contacts: Magneto-resistance is a physical effect of great fundamental and industrial\ninterest since it is the basis for the magnetic field sensors used in computer\nread-heads and Magnetic Random Access Memories. As device dimensions are\nreduced, some important physical length scales for magnetism and electrical\ntransport will soon be attained. Ultimately, there is a strong need to know if\nthe physical phenomena responsible for magneto-resistance still hold at the\natomic scale. Here, we show that the anisotropy of magneto-resistance is\ngreatly enhanced in atomic size constrictions. We explain this physical effect\nby a change in the electronic density of states in the junction when the\nmagnetization is rotated, as supported by our ab-initio calculations. This\nstems from the \"spin-orbit coupling\" mechanism linking the shape of the\norbitals with the spin direction. This sensitively affects the conductance of\natomic contacts which is determined by the overlap of the valence orbitals."
    },
    {
        "anchor": "Excitons in Cu2O -- from Quantum Wells to Bulk Crystals and Additional\n  Boundary Conditions for Rydberg Exciton-Polaritons: We propose a scheme for calculation of optical functions of a semiconductor\nwith Rydberg excitons, for a wide interval of dimensions. We start with\n2-dimensional structure, then going to thin films and ending on 3-dimensional\nbulk crystals. The calculations including the polaritons are performed, the\ncase of large number of polariton branches is discussed and obtained\ntheoretical absorption spectra show good agreement with experimental data.",
        "positive": "Look-alike Landau levels in locally biased twisted bilayer graphene: The large lattice constant of Moire superlattice formed in twisted bilayer\ngraphene for small twist enables observing the Landau levels splitting into\nHofstadter butterflies in energy spectra for moderate magnetic field. This is\nexpected for generic system under homogeneous bias conditions but its\nrobustness against spatial potential fluctuations is left open question. We\nstudy the energy structure of twisted bilayer system in dependence of both, the\nhomogeneous magnetic field and the bias voltage applied exclusively in its\ncentral part. Although the translational symmetry is broken, the energy states\nmainly localized outside the central region may still condense on Landau levels\nand these would split revealing self-similarity feature. Moreover, besides the\ngeneric branch of energy states with zero-mode Landau level at charge\nneutrality point, when both layers are biased with the same voltage, the second\nlook-alike energy branch shifted upwards can be developed by states largely\nlocalized in central region. Otherwise, for counter-biasing of layers, only\ngeneric branch exists but with lowest Landau layers flanked by either,\nhole-like and electron-like states localized at the top or at the bottom layer\nof central biased part of twisted bilayer system."
    },
    {
        "anchor": "Spin Wave Propagation through Antiferromagnet/Ferromagnet Interface: We study the problem of controlling spin waves propagation through an\nantiferromagnet/ferromagnet interface via tuning material parameters. It is\ndone by introducing the degree of sublattice noncompensation of antiferromagnet\n(DSNA), which is a physical characteristic of finite-thickness interfaces. The\nDSNA value can be varied by designing interfaces with a particular disorder or\ncurvilinear geometry. We describe a spin-wave propagation through any designed\nantiferromagnet/ferromagnet interface considering a variable DSNA and\nappropriate boundary conditions. As a result, we calculate the physical\ntransmittance and reflectance of the spin waves as a function of frequency and\nshow how to control them via the exchange parameters tuning.",
        "positive": "Theory of the Magnetic-Field-Induced Insulator in Neutral Graphene: Recent experiments have demonstrated that neutral graphene sheets have an\ninsulating ground state in the presence of an external magnetic field. We\nreport on a $\\pi$-band tight-binding-model Hartree-Fock calculation which\nexamines the competition between distinct candidate insulating ground states.\nWe conclude that for graphene sheets on substrates the ground state is most\nlikely a field-induced spin-density-wave, and that a charge density wave state\nis possible for suspended samples. Neither of these density-wave states support\ngapless edge excitations."
    },
    {
        "anchor": "Weyl points in the multi-terminal Hybrid Superconductor-Semiconductor\n  Nanowire devices: The technology of superconductor-semiconductor nanowire devices has matured\nin the last years in the quest for topological quantum computing. This makes it\nfeasible to make more complex and sophisticated devices. We investigate\nmulti-terminal superconductor-semiconductor wires to access feasibility of\nanother topological phenomenon: Weyl singularities in their spectrum. We have\nfound an abundance of Weyl singularities for devices with intermediate size of\nthe electrodes. We describe their properties and the ways the singularities\nemerge and disappear upon variation of the setup parameters.",
        "positive": "Photoninduced Weyl half-metal phase and spin filter effect from\n  topological Dirac semimetals: Recently discovered Dirac semimetals (DSMs) with two Dirac nodes, such as\nNa$_{3}$Bi and Cd$_{2}$As$_{3}$, are regarded to carry the $\\mathbb{Z}_{2}$\ntopological charge in addition to the chiral charge. Here, we study the Floquet\nphase transition of $\\mathbb{Z}_{2}$ topological DSMs subjected to a beam of\ncircularly polarized light. Due to the resulting interplay of the chiral and\n$\\mathbb{Z}_{2}$ charges, the Weyl nodes are not only chirality-dependent but\nalso spin-dependent, which constrains the behaviors in creation and\nannihilation of the Weyl nodes in pair. Interestingly, we find a novel phase:\nOne spinband is in Weyl semimetal phase while the other spinband is in\ninsulator phase, and we dub it Weyl half-metal (WHM) phase. We further study\nthe spin-dependent transport in a Dirac-Weyl semimetal junction and find a spin\nfilter effect as a fingerprint of existence of the WHM phase. The proposed spin\nfilter effect, based on the WHM bulk band, is highly tunable in a broad\nparameter regime and robust against magnetic disorder, which is expected to\novercome the shortcomings of the previously proposed spin filter based on the\ntopological edge/surface states. Our results offer a unique opportunity to\nexplore the potential applications of topological DSMs in spintronics."
    },
    {
        "anchor": "Multiple layer local oxidation for fabricating semiconductor\n  nanostructures: Coupled semiconductor nanostructures with a high degree of tunability are\nfabricated using local oxidation with a scanning force microscope. Direct\noxidation of the GaAs surface of a Ga[Al]As heterostructure containing a\nshallow two-dimensional electron gas is combined with the local oxidation of a\nthin titanium film evaporated on top. A four-terminal quantum dot and a double\nquantum dot system with integrated charge readout are realized. The structures\nare tunable via in-plane gates formed by isolated regions in the electron gas\nand by mutually isolated regions of the Ti film acting as top gates. Coulomb\nblockade experiments demonstrate the high quality of this fabrication process.",
        "positive": "Hyperfine interaction mediated electric-dipole spin resonance: the role\n  of frequency modulation: The electron spin in a semiconductor quantum dot can be coherently controlled\nby an external electric field, an effect called electric-dipole spin resonance\n(EDSR). Several mechanisms can give rise to the EDSR effect, among which there\nis a hyperfine mechanism, where the spin-electric coupling is mediated by the\nelectron-nucleus hyperfine interaction. Here, we investigate the influence of\nfrequency modulation (FM) on the spin-flip efficiency. Our results reveal that\nFM plays an important role in the hyperfine mechanism. Without FM, the electric\nfield almost cannot flip the electron spin; the spin-flip probability is only\nabout 20%. While under FM, the spin-flip probability can be improved to\napproximately 70%. In particular, we find that the modulation amplitude has a\nlower bound, which is related to the width of the fluctuated hyperfine field."
    },
    {
        "anchor": "Topological central charge from Berry curvature: gravitational anomalies\n  in trial wavefunctions for topological phases: We show that the topological central charge of a topological phase can be\ndirectly accessed from the ground-state wavefunctions for a system on a surface\nas a Berry curvature produced by adiabatic variation of the metric on the\nsurface, at least up to addition of another topological invariant that arises\nin some cases. For trial wavefunctions that are given by conformal blocks\n(chiral correlation functions) in a conformal field theory (CFT), we carry out\nthis calculation analytically, using the hypothesis of generalized screening.\nThe topological central charge is found to be that of the underlying CFT used\nin the construction, as expected. The calculation makes use of the\ngravitational anomaly in the chiral CFT. It is also shown that the Hall\nconductivity can be obtained in an analogous way from the U($1$) gauge anomaly.",
        "positive": "Effective one-band approach for the spin splittings in quantum wells: The spin-orbit interaction of 2D electrons in the quantum wells grown from\nthe III-V semiconductors consists of the two parts with different symmetry: the\nBychkov-Rashba and the Dresselhaus terms. The last term is usually attributed\nto the bulk spin-orbit Hamiltonian which reflects the Td symmetry of the\nzincblende lattice. While it is known that the quantum well interfaces may also\ncontribute to the Dresselhaus term, the exact structure and the relative\nimportance of the interface and the bulk contributions are not well understood\nyet. To compare the bulk contribution with the interface one, we perform\ntight-binding calculations of the spin splittings of the electron levels in\n[100] GaAs/AlGaAs quantum wells and analyze the obtained spin splittings within\nthe one-band effective mass electron Hamiltonian containing the two interface\ncontributions to the Dresselhaus term. We show that the dependencies of the\nspin splittings on the quantum well width and the electric field along the\ngrowth direction are perfectly reproduced by the analytical one-band\ncalculations and the magnitude of the interface contribution to the spin-orbit\ninteraction for sufficiently narrow quantum wells is of the same order as the\ncontribution from the bulk Dresselhaus Hamiltonian."
    },
    {
        "anchor": "A probabilistic model of resistance jumps in memristive devices: Resistance switching memory cells such as electrochemical metallization cells\nand valence change mechanism cells have the potential to revolutionize\ninformation processing and storage. However, the creation of deterministic\nresistance switching devices is a challenging problem that is still open. At\npresent, the modeling of resistance switching cells is dominantly based on\ndeterministic models that fail to capture the cycle-to-cycle variability\nintrinsic to these devices. Herewith we introduce a state probability\ndistribution function and associated integro-differential equation to describe\nthe switching process consisting of a set of stochastic jumps. Numerical and\nanalytical solutions of the equation have been found in two model cases. This\nwork expands the toolbox of models available for resistance switching cells and\nrelated devices, and enables a rigorous description of intrinsic physical\nbehavior not available in other models.",
        "positive": "Pfaffian and fragmented states at nu=5/2 in quantum Hall droplets: When a gas of electrons is confined to two dimensions, application of a\nstrong magnetic field may lead to startling phenomena such as emergence of\nelectron pairing. According to a theory this manifests itself as appearance of\nthe fractional quantum Hall effect with a quantized conductivity at an unusual\nhalf-integer nu=5/2 Landau level filling. Here we show that similar electron\npairing may occur in quantum dots where the gas of electrons is trapped by\nexternal electric potentials into small quantum Hall droplets. However, we also\nfind theoretical and experimental evidence that, depending on the shape of the\nexternal potential, the paired electron state can break down, which leads to a\nfragmentation of charge and spin densities into incompressible domains. The\nfragmentation of the quantum Hall states could be an issue in the proposed\nexperiments that aim to probe for non-abelian quasi-particle characteristics of\nthe nu=5/2 quantum Hall state."
    },
    {
        "anchor": "Proposal for detecting nodal-line semimetal surface-states with resonant\n  spin-flipped reflection: Topological nodal-line semimetals are predicted to exhibit unique\ndrumhead-like surface states (DSS). Yet, a direct detection of such states\nremains a challenge. Here, we propose spin-resolved transport in a junction\nbetween a normal metal and a spin-orbit coupled nodal-line semimetal as the\nmechanism for their detection. Specifically, we find that in such a device, the\nDSS induce resonant spin-flipped reflection. This effect can be probed by both\nvertical spin transport and lateral charge transport between anti-parallel\nmagnetic terminals. In the tunneling limit of the junction, both spin and\ncharge conductances exhibit a resonant peak around zero energy, providing a\nunique evidence of the DSS. This signature is robust to both dispersive DSS and\ninterface disorder. Based on numerical calculations, we show that the scheme\ncan be implemented in the topological semimetal HgCr$_2$Se$_4$.",
        "positive": "Proximity induced room-temperature ferromagnetism in graphene probed\n  with spin currents: The introduction and control of ferromagnetism in graphene opens up a range\nof new directions for fundamental and applied studies. Several approaches have\nbeen pursued so far, such as introduction of defects, functionalization with\nadatoms, and shaping of graphene into nanoribbons with well-defined zigzag\nedges. A more robust and less invasive method utilizes the introduction of an\nexchange interaction by a ferromagnetic insulator in proximity with graphene.\n  Here we present a direct measurement of the exchange interaction in room\ntemperature ferromagnetic graphene. We study the spin transport in exfoliated\ngraphene on a yttrium-iron-garnet substrate where the observed spin precession\nclearly indicates the presence and strength of an exchange field that is an\nunambiguous evidence of induced ferromagnetism. We describe the results with a\nmodified Bloch diffusion equation and extract an average exchange field of the\norder of 0.2 T. Further, we demonstrate that a proximity induced 2D ferromagnet\ncan efficiently modulate a spin current by controlling the direction of the\nexchange field. These results can create a building block for magnetic-gate\ntuneable spin transport in one-atom-thick spintronic devices."
    },
    {
        "anchor": "Chiral 1D Floquet topological insulators beyond rotating wave\n  approximation: We study one-dimensional (1D) Floquet topological insulators with chiral\nsymmetry going beyond the standard rotating wave approximation. The occurrence\nof many anticrossings between Floquet replicas leads to a dramatic extension of\nphase diagram regions with stable topological edge states (TESs). We present an\nexplicit construction of all TESs in terms of a truncated Floquet Hamiltonian\nin frequency space, prove the bulk-boundary correspondence, and analyze the\nstability of the TESs in terms of their localization lengths. We propose\nexperimental tests of our predictions in curved bilayer graphene.",
        "positive": "Two-dimensional non-Hermitian topological phases induced by asymmetric\n  hopping in a one-dimensional superlattice: Non-Hermitian systems can host topological states with novel topological\ninvariants and bulk-edge correspondences that are distinct from conventional\nHermitian systems. Here we show that two unique classes of non-Hermitian 2D\ntopological phases, a 2$\\mathbb{Z}$ non-Hermitian Chern insulator and a\n$\\mathbb{Z}_{2}$ topological semimetal, can be realized by tuning staggered\nasymmetric hopping strengths in a 1D superlattice. These non-Hermitian\ntopological phases support real edge modes due to robust\n$\\mathcal{PT}$-symmetric-like spectra and can coexist in certain parameter\nregime. The proposed phases can be experimentally realized in photonic or\natomic systems and may open an avenue for exploring novel classes of\nnon-Hermitian topological phases with 1D superlattices."
    },
    {
        "anchor": "Stochastic exciton-scattering theory of optical lineshapes: Renormalized\n  many-body contributions: Spectral line-shapes provide a window into the local environment coupled to a\nquantum transition in the condensed phase. In this paper, we build upon a\nstochastic model to account for non-stationary background processes produced by\nbroad-band pulsed laser stimulation. In particular, we consider the\ncontribution of pair-fluctuations arising from the full bosonic many-body\nHamiltonian within a mean-field approximation, treating the coupling to the\nsystem as a stochastic noise term. Using the It{\\^o} transformation, we\nconsider two limiting cases for our model which lead to a connection between\nthe observed spectral fluctuations and the spectral density of the environment.\nIn the first case, we consider a Brownian environment and show that this\nproduces spectral dynamics that relax to form dressed excitonic states and\nrecover an Anderson-Kubo-like form for the spectral correlations. In the second\ncase, we assume that the spectrum is Anderson-Kubo like, and invert to\ndetermine the corresponding background. Using the Jensen inequality, we obtain\nan upper limit for the spectral density for the background. The results\npresented here provide the technical tools for applying the stochastic model to\na broad range of problems.",
        "positive": "Three-dimensional tomographic imaging of the magnetization vector field\n  using Fourier transform holography: In recent years, interest in expanding from 2D to 3D systems has grown in the\nmagnetism community, from exploring new geometries to broadening the knowledge\non the magnetic textures present in thick samples, and with this arise the need\nfor new characterization techniques, in particular tomographic imaging. Here,\nwe present a new tomographic technique based on Fourier transform holography, a\nlensless imaging technique that uses a known reference in the sample to\nretrieve the object of interest from its diffraction pattern in one single step\nof calculation, overcoming the phase problem inherent to reciprocal-space-based\ntechniques. Moreover, by exploiting the phase contrast instead of the\nabsorption contrast, thicker samples can be investigated. We obtain a 3D\nfull-vectorial image of a 800 nm-thick extended Fe/Gd multilayer in a\n5$\\mu$m-diameter circular field of view with a resolution of approximately 80\nnm. The 3D image reveals worm-like domains with magnetization pointing mostly\nout of plane near the surface of the sample but that falls in-plane near the\nsubstrate. Since the FTH setup is fairly simple, it allows modifying the sample\nenvironment. Therefore, this technique could enable in particular a 3D view of\nthe magnetic configuration's response to an external magnetic field."
    },
    {
        "anchor": "Local Symmetry Breaking Drives Picosecond Spin Domain Formation in\n  Polycrystalline Semiconducting Films: Photoinduced spin-charge interconversion in semiconductors with spin-orbit\ncoupling could provide a route to optically addressable spintronics without the\nuse of external magnetic fields. A central question is whether the resulting\nspin-associated charge currents are robust to structural disorder, which is\ninherent to polycrystalline semiconductors that are desirable for device\napplications. Using femtosecond circular polarization-resolved pump-probe\nmicroscopy on polycrystalline halide perovskite thin films, we observe the\nphotoinduced ultrafast formation of spin-polarized positive and, unexpectedly,\nnegative spin domains on the micron scale formed through lateral currents.\nFurther, the polarization of these domains and lateral transport direction is\nswitched upon switching the polarization of the pump helicity. Micron scale\nvariations in the intensity of optical second-harmonic generation and vertical\npiezoresponse suggest that the spin domain formation is driven by the presence\nof strong local inversion symmetry breaking via inter-grain structural\ndisorder. We propose that this leads to spatially varying Rashba-like spin\ntextures that drive spin-momentum locked currents, leading to local spin\naccumulation. Our results establish ultrafast spin domain formation in\npolycrystalline semiconductors as a new optically addressable platform for\nnanoscale spin-device physics.",
        "positive": "A 2x2 quantum dot array with controllable inter-dot tunnel couplings: The interaction between electrons in arrays of electrostatically defined\nquantum dots is naturally described by a Fermi-Hubbard Hamiltonian. Moreover,\nthe high degree of tunability of these systems make them a powerful platform to\nsimulate different regimes of the Hubbard model. However, most quantum dot\narray implementations have been limited to one-dimensional linear arrays. In\nthis letter, we present a square lattice unit cell of 2$\\times$2 quantum dots\ndefined electrostatically in a AlGaAs/GaAs heterostructure using a double-layer\ngate technique. We probe the properties of the array using nearby quantum dots\noperated as charge sensors. We show that we can deterministically and\ndynamically control the charge occupation in each quantum dot in the single- to\nfew-electron regime. Additionally, we achieve simultaneous individual control\nof the nearest-neighbor tunnel couplings over a range 0-40~$\\mu$eV. Finally, we\ndemonstrate fast ($\\sim 1$~$\\mu$s) single-shot readout of the spin state of\nelectrons in the dots, through spin-to-charge conversion via Pauli spin\nblockade. These advances pave the way to analog quantum simulations in two\ndimensions, not previously accessible in quantum dot systems."
    },
    {
        "anchor": "Frequency enhancement and power tunability in tilted polarizer\n  spin-torque nano oscillator: In the absence of an applied magnetic field, a spin-torque nano\noscillator(STNO) with a tilted polarizer is studied using numerical simulation\nof the associated Landau-Lifshitz-Gilbert-Slonczewski equation. We find\nconsiderable enhancement of frequency by tilting the polarizer out-of-plane\nappropriately. Also, we observe improved tunability of frequency of\noscillations from 15 GHz to 75 GHz and increment in the power spectral density\nby current and tilt angle. In addition, our findings and insights pave a simple\nway for nanoscale level microwave generators to be implemented.",
        "positive": "Electrons surfing on a sound wave as a platform for quantum optics with\n  flying electrons: Electrons in a metal are indistinguishable particles that strongly interact\nwith other electrons and their environment. Isolating and detecting a single\nflying electron after propagation to perform quantum optics like experiments at\nthe single electron level is therefore a challenging task. Up to date, only few\nexperiments have been performed in a high mobility two-dimensional electron gas\nwhere the electron propagates almost ballistically. Flying electrons were\ndetected via the current generated by an ensemble of electrons and electron\ncorrelations were encrypted in the current noise. Here we demonstrate the\nexperimental realisation of high efficiency single electron source and single\nelectron detector for a quantum medium where a single electron is propagating\nisolated from the other electrons through a one-dimensional channel. The moving\npotential is excited by a surface acoustic wave, which carries the single\nelectron along the 1D-channel at a speed of 3\\mum/ns. When such a quantum\nchannel is placed between two quantum dots, a single electron can be\ntransported from one quantum dot to the other, which is several micrometres\napart, with a quantum efficiency of emission and detection of 96% and 92%,\nrespectively. Furthermore, the transfer of the electron can be triggered on a\ntimescale shorter than the coherence time T2* of GaAs spin qubits6. Our work\nopens new avenues to study the teleportation of a single electron spin and the\ndistant interaction between spatially separated qubits in a condensed matter\nsystem."
    },
    {
        "anchor": "Thermal rectification through a nonlinear quantum resonator: We present a comprehensive and systematic study of thermal rectification in a\nprototypical low-dimensional quantum system -- a non-linear resonator: we\nidentify necessary conditions to observe thermal rectification and we discuss\nstrategies to maximize it. We focus, in particular, on the case where\nanharmonicity is very strong and the system reduces to a qubit. In the latter\ncase, we derive general upper bounds on rectification which hold in the weak\nsystem-bath coupling regime, and we show how the Lamb shift can be exploited to\nenhance rectification. We then go beyond the weak-coupling regime by employing\ndifferent methods: i) including co-tunneling processes, ii) using the\nnon-equilibrium Green's function formalism and iii) using the Feynman-Vernon\npath integral approach. We find that the strong coupling regime allows us to\nviolate the bounds derived in the weak-coupling regime, providing us with clear\nsignatures of high order coherent processes visible in the thermal\nrectification. In the general case, where many levels participate to the system\ndynamics, we compare the heat rectification calculated with the equation of\nmotion method and with a mean-field approximation. We find that the former\nmethod predicts, for a small or intermediate anharmonicity, a larger\nrectification coefficient.",
        "positive": "Yu-Shiba-Rusinov states in real metals: Theoretical descriptions of Yu-Shiba-Rusinov (YSR) states induced by magnetic\nimpurities inside the gap of a superconductor typically rely on a classical\nspin model or are restricted to spin-1/2 quantum spins. These models fail to\naccount for important aspects of YSR states induced by transition-metal\nimpurities, including the effects of higher quantum spins coupled to several\nconduction-electron channels, crystal or ligand-field effects, and magnetic\nanisotropy. We introduce and explore a zero-bandwidth model, which incorporates\nthese aspects, is readily solved numerically, and analytically tractable in\nseveral limiting cases. The principal simplification of the model is to neglect\nKondo renormalizations of the exchange couplings between impurity spin and\nconduction electrons. Nevertheless, we find excellent correspondence in those\ncases, in which we can compare our results to existing\nnumerical-renormalization-group calculations. We apply the model to obtain and\nunderstand phase diagrams as a function of pairing strength and magnetic\nanisotropy as well as subgap excitation spectra. The single-channel case is\nmost relevant for transition-metal impurities embedded into metallic\ncoordination complexes on superconducting substrates, while the multi-channel\ncase models transition-metal adatoms."
    },
    {
        "anchor": "Ferromagnetic resonance linewidth in coupled layers with easy-plane and\n  perpendicular magnetic anisotropies: Magnetic bilayers with different magnetic anisotropy directions are\ninteresting for spintronic appli- cations as they offer the possibility to\nengineer tilted remnant magnetization states. We investigate the ferromagnetic\nresonance (FMR) linewidth of modes associated with two interlayer exchange-\ncoupled ferromagnetic layers, the first a CoNi multilayer with a perpendicular\nmagnetic anisotropy, and the second a CoFeB layer with an easy-plane\nanisotropy. For antiferromagnetic interlayer ex- change coupling, elevated FMR\nlinewidths are observed below a characteristic field. This is in contrast to\nwhat is found in uncoupled, ferromagnetically coupled and single ferromagnetic\nlayers in which the FMR linewidth increases monotonically with field. We show\nthat the characteristic field at which there is a dramatic increase in FMR\nlinewidth can be understood using a macrospin model with Heisenberg-type\nexchange coupling between the layers.",
        "positive": "Topological p-n Junction: We consider a junction between surface $p$-type and surface $n$-type on an\nideal topological insulator in which carrier type and density in two adjacent\nregions are locally controlled by composition graded doping or electrical\ngating. Such junction setting on topological insulators are fundamental for\npossible device application. A single gapless chiral edge state localized along\nthe junction interface appears in the presence of an external magnetic field,\nand it can be probed by scanning tunneling microscopy and transport\nmeasurements. We propose to realize this topological \\emph{p-n} junction in\n(Bi$_{1-x}$Sb$_x$)$_2$Te$_3$, which has insulating bulk properties and a\ntunable surface state across the Dirac cone."
    },
    {
        "anchor": "Rotational strain in Weyl semimetals: A continuum approach: The coupling of lattice deformations to the low energy electronic excitations\nof Dirac matter involve novel types of electron--phonon couplings as the\ncelebrated elastic gauge fields first analyzed in graphene. In the continuum\nlow energy approach, lattice deformations coupling to the electronic degrees of\nfreedom are characterized by the (symmetric) strain tensor defined in\nelasticity theory. We review these couplings in Weyl semimetals and examine the\ncoupling of electronic excitations to the antisymmetric part of the deformation\ngradient tensor associated to rotational strain. The new couplings, absent in\nthe two dimensional materials, have important physical implications: they give\nrise to new elastic gauge fields, contribute to the deformation potential, tilt\nthe cones and generate new pseudo--Zeeman couplings.",
        "positive": "Robust propagating in-gap modes due to spin-orbit domain walls in\n  graphene: Recently, great experimental efforts towards designing topological electronic\nstates have been invested in layered incommensurate heterostructures which form\nvarious nano- and meso-scale domains. In particular, it has become clear that a\ndelicate interplay of different spin-orbit terms is induced in graphene on\ntransition metal dichalcogenide substrates. We therefore theoretically study\nvarious types of domain walls in spin-orbit coupling in graphene looking for\nrobust one-dimensional propagating electronic states. To do so, we use an\ninterface Chern number and a spectral flow analysis in the low-energy theory\nand contrast our results to the standard arguments based on valley-Chern\nnumbers or Chern numbers in continuum models. Surprisingly, we find that a\nsign-changing domain wall in valley-Zeeman spin-orbit coupling binds two robust\nKramers pairs, within the bulk gap opened due to a simultaneous presence of\nRashba coupling. We also study the robustness to symmetry breaking and lattice\nbackscattering effects in tight-binding models. We show an explicit mapping of\nour valley-Zeeman domain wall to a domain wall in gated spinless bilayer\ngraphene. We discuss the possible spectroscopic and transport signatures of\nvarious types of spin-orbit coupling domain walls in heterostructures."
    },
    {
        "anchor": "Quantum dot detects Majorana modes of both chiralities: A tunneling junction between normal electrode and a topological\nsuperconducting wire, mediated by a quantum dot, is considered theoretically.\nWe show that the presence of the dot in the junction can be advantageous to\nMajorana zero modes identification. Namely, we demonstrate that for the dot\nstrongly coupled to the wire, the Majorana mode from the upper chiral sub-band\n\"leaks\" into the dot, providing supplementary information on Majorana mode\nformation. Thus, both the Zeeman-split dot sub-levels detect Majorana partners\nof a Kramers pair, formed at the wire end. The characteristic three-peak\nstructures in both spin sectors of the spectral density of the dot, distinguish\nfrom the trivial scenario of one Andreev resonance at Fermi energy produced\nexclusively by the dot's spin sub-levels.",
        "positive": "Wafer-scale fabrication of 2D van der Waals heterojunctions for\n  efficient and broadband photodetection: A variety of fabrication methods for van der Waals heterostructures have been\ndemonstrated; however, their wafer-scale deposition remains a challenge. Here\nwe report few-layer van der Waals PtS2/PtSe2 heterojunction photodiodes\nfabricated on a 2\" SiO2/Si substrate that is only limited by the size of work\nchamber of the growth equipment, offering throughputs necessary for practical\napplications. Theoretical simulation results show that the bandgap of PtS2 is\nshrunk to half of its original size in the PtS2/PtSe2 heterostructures, while\nPtSe2 exhibits a limited response to the coupling. Both PtSe2 and PtS2 layers\nin the coupled system are still semiconductors. Dynamic photovoltaic switching\nin the heterojunctions is observed at zero-volt state under laser illuminations\nof 532 to 2200 nm wavelengths. The PtS2/PtSe2 photodiodes show excellent\ncharacteristics in terms of a high photoresponsivity of 361 mAW-1, an external\nquantum efficiency (EQE) of 84%, and a fast response speed (66 ms). The\nwafer-scale production of 2D photodiodes in this work accelerates the\npossibility of 2D materials for practical applications in the next-generation\nenergy-efficient electronics."
    },
    {
        "anchor": "Fast and slow edges in bilayer graphene nanoribbons: Tuning the\n  transition from band- to Mott-insulator: We show that gated bilayer graphene zigzag ribbons possess a fast and a slow\nedge, characterized by edge state velocities that differ due to non-negligible\nnext-nearest-neighbor hopping elements. By applying bosonization and\nrenormalization group methods, we find that the slow edge can acquire a sizable\ninteraction-induced gap, which is tunable via an external gate voltage V_{g}.\nIn contrast to the gate-induced gap in the bulk, the interaction-induced gap\ndepends non-monotonously on the on-site potential V.",
        "positive": "Orbital shift-induced boundary obstructed topological materials with a\n  large energy gap: We propose boundary obstructed topological phases caused by Wannier orbital\nshift between ordinary atomic sites, which, however, cannot be indicated by\nsymmetry eigenvalues at high symmetry momenta (symmetry indicators) in bulk. On\nthe open boundary, Wannier charge centers can shift to different atoms from\nthose in bulk, leading to in-gap surface states, higher-order hinge states or\ncorner states. To demonstrate such orbital-shift-induced boundary obstructed\ntopological insulators, we predict eight material candidates, all of which were\noverlooked in present topological databases. Metallic surface states, hinge\nstates, or corner states cover the large bulk energy gap (for example, more\nthan 1 eV in TlGaTe$_2$) at related boundary, which are ready for experimental\ndetection. Additionally, we find these materials are also fragile topological\ninsulators with hourglass like surface states."
    },
    {
        "anchor": "Topological States in Two-Dimensional Su-Schrieffer-Heeger Models: We study the topological properties of the generalized two-dimensional (2D)\nSu-Schrieffer-Heeger (SSH) models. We show that a pair of Dirac points appear\nin the Brillouin zone (BZ), consisting a semimetallic phase. Interestingly, the\nlocations of these Dirac points are not pinned to any high-symmetry points of\nthe BZ but tunable by model parameters. Moreover, the merging of two Dirac\npoints undergoes a novel topological phase transition, which leads to either a\nweak topological insulator or a nodal-line metallic phase. We demonstrate these\nproperties by constructing two specific models, which we referred as type-I and\ntype-II 2D SSH models. The feasible experimental platforms to realize our\nmodels are also discussed.",
        "positive": "Superfluidity of 4He nanoclusters in confinement: Structure and superfluid response of nanoscale size helium-four clusters\nenclosed in spherical cavities are studied by computer simulations. The curved\nsurface causes the formation of well-defined concentric shells, thus imparting\nto the system a very different structure from that of free standing clusters.\nOn a strongly attractive substrate, superfluidity is only observed at low\ndensity, in the single layer coating the inner surface of the cavity. If the\nsubstrate is very weak (e.g., Li), on the other hand, a superfluid two-shell\nstructure can form, whose physical properties interpolate between two and three\ndimensions. It is shown how experimental signatures of this physical behavior\ncan be detected through measurements of the momentum distribution."
    },
    {
        "anchor": "Quasi-relativistic behavior of cold atoms in light fields: We study the influence of three laser beams on the center of mass motion of\ncold atoms with internal energy levels in a tripod configuration. We show that\nsimilar to electrons in graphene the atomic motion can be equivalent to the\ndynamics of ultra-relativistic two-component Dirac fermions. We propose and\nanalyze an experimental setup for observing such a quasi-relativistic motion of\nultracold atoms. We demonstrate that the atoms can experience negative\nrefraction and focussing by Veselago-type lenses. We also show how the chiral\nnature of the atomic motion manifests itself as an oscillation of the atomic\ninternal state population which depends strongly on the direction of the center\nof mass motion. For certain directions an atom remains in its initial state,\nwhereas for other directions the populations undergo oscillations between a\npair of internal states.",
        "positive": "Dynamics of Quantum Noise in a Tunnel Junction under ac Excitation: We report the first measurement of the \\emph{dynamical response} of shot\nnoise (measured at frequency $\\omega$) of a tunnel junction to an ac excitation\nat frequency $\\omega_0$. The experiment is performed in the quantum regime,\n$\\hbar\\omega\\sim\\hbar\\omega_0\\gg k_BT$ at very low temperature T=35mK and high\nfrequency $\\omega_0/2\\pi=6.2$ GHz. We observe that the noise responds in phase\nwith the excitation, but not adiabatically. The results are in very good\nagreement with a prediction based on a new current-current correlator."
    },
    {
        "anchor": "Brownian dynamics of Dirac fermions in twisted bilayer graphene: Brownian dynamics of Dirac fermions in twisted bilayer graphene is\ninvestigated within the framework of semiclassical relativistic Langevin\nequations. We find that under the influence of orthogonal, commensurate ac\ndrives in the periodic ratchet potential of a substrate, the charge carriers in\nthe system exhibit pronounced random dynamics, tuned by the twist angle, making\ntwisted bilayer graphene distinguishable from monolayer graphene. It is shown\nthat as threshold twist angle matches the optimal angle, deterministic running\nstates appear in the limit of weak thermal noise where the diffusion rate is\nenhanced significantly compared to bare thermal diffusion. Analysis of the real\nspace trajectories and diffusion coefficient illustrates the significant role\nof thermal noise in the random motion of Dirac fermions. In addition, we find\nthat the Brownian particle shows remarkable ratchet effect as a net current.",
        "positive": "Thermoelectric transport in two-dimensional topological insulator state\n  based on HgTe quantum well: The thermoelectric response of HgTe quantum wells in the state of\ntwo-dimensional topological insulator (2D TI) has been studied experimentally.\nAmbipolar thermopower, typical for an electron-hole system, has been observed\nacross the charge neutrality point, where the carrier type changes from\nelectrons to holes according to the resistance measurements. The hole-type\nthermopower is much stronger than the electron-type one. The thermopower\nlinearly increases with temperature. We present a theoretical model which\naccounts for both the edge and bulk contributions to the electrical\nconductivity and thermoelectric effect in a 2D TI, including the effects of\nedge to bulk leakage. The model, contrary to previous theoretical studies,\ndemonstrates that the 2D TI is not expected to show anomalies of thermopower\nnear the band conductivity threshold, which is consistent with our experimental\nresults. Based on the experimental data and theoretical analysis, we conclude\nthat the observed thermopower is mostly of the bulk origin, while the\nresistance is determined by both the edge and bulk transport."
    },
    {
        "anchor": "Interfacial Effects on the Optical Properties of CdTe/CdS Quantum Dots: Using a combination of continuous wave and time-resolved spectroscopy, we\nstudy the effects of interfacial conditions on the radiative lifetimes and\nphotoluminescence intensities of colloidal CdTe/CdS quantum dots (QDs) embedded\nin a three-dimensional nanostructured silicon (NSi) matrix. The NSi matrix was\nthermally oxidized under different conditions to change the interfacial oxide\nthickness. QDs embedded in a NSi matrix with ~0.5 nm of interfacial oxide\nexhibited reduced photoluminescence intensity and nearly five times shorter\nradiative lifetimes (~16 ns) compared to QDs immobilized within completely\noxidized, nanostructured silica (NSiO2) frameworks (~78 ns). Optical absorption\nby the sub-nm oxidized NSi matrix partially lowers QD emission intensities\nwhile non-radiative carrier recombination and phonon assisted transitions\ninfluenced by defect sites within the oxide and NSi are believed to be the\nprimary factors limiting the QD exciton lifetimes in the heterostructures.",
        "positive": "Nonreciprocal electron hydrodynamics under magnetic fields: applications\n  to nonreciprocal surface magnetoplasmons: Recent experiments have elucidated that novel nonequilibrium states inherent\nin the so-called hydrodynamic regime are realized in ultrapure metals with\nsufficiently strong momentum-conserving scattering. In this letter, we\nformulate a theory of electron hydrodynamics with broken inversion symmetry\nunder magnetic fields and find that novel terms emerge in hydrodynamic\nequations which play a crucial role for the realization of the nonreciprocal\nresponses. Specifically, we clarify that there exist a novel type of\nnonreciprocal collective modes dubbed nonreciprocal surface magnetoplasmons\narising from an interplay between magnetic fields and the orbital magnetic\nmoment. We reveal that these nonreciprocal collective modes indeed give rise to\nthe nonreciprocity in magneto-optical responses such as the reflectivity. The\nphysics discussed here will bridge the two important notions of\nmagnetoplasmonics and nonreciprocity in electron hydrodynamic materials with\ninversion symmetry breaking and magnetic fields."
    },
    {
        "anchor": "Higher Order Topological Insulator via Periodic Driving: We theoretically investigate a periodically driven semimetal based on a\nsquare lattice. The possibility of engineering both Floquet Topological\nInsulator featuring Floquet edge states and Floquet higher order topological\ninsulating phase, accommodating topological corner modes has been demonstrated\nstarting from the semimetal phase, based on Floquet Hamiltonian picture.\nTopological phase transition takes place in the bulk quasi-energy spectrum with\nthe variation of the drive amplitude where Chern number changes sign from $+1$\nto $-1$. This can be attributed to broken time-reversal invariance\n($\\mathcal{T}$) due to circularly polarized light. When the discrete four-fold\nrotational symmetry ($\\mathcal{C}_4$) is also broken by adding a Wilson mass\nterm along with broken $\\mathcal{T}$, higher order topological insulator\n(HOTI), hosting in-gap modes at all the corners, can be realized. The Floquet\nquadrupolar moment, calculated with the Floquet states, exhibits a quantized\nvalue of $ 0.5$ (modulo 1) identifying the HOTI phase. We also show the\nemergence of the {\\it{dressed corner modes}} at quasi-energy $\\omega/2$\n(remnants of zero modes in the quasi-static high frequency limit), where\n$\\omega$ is the driving frequency, in the intermediate frequency regime.",
        "positive": "Transport mirages in single-molecule devices: Molecular systems can exhibit a complex, chemically tailorable inner\nstructure which allows for targeting of specific mechanical, electronic and\noptical properties. At the single-molecule level, two major complementary ways\nto explore these properties are molecular quantum-dot structures and scanning\nprobes. This article outlines comprehensive principles of electron-transport\nspectroscopy relevant to both these approaches and presents a new,\nhigh-resolution experiment on a high-spin single-molecule junction exemplifying\nthese principles. Such spectroscopy plays a key role in further advancing our\nunderstanding of molecular and atomic systems, in particular the relaxation of\ntheir spin. In this joint experimental and theoretical analysis, particular\nfocus is put on the crossover between resonant regime [single-electron\ntunneling (SET)] and the off-resonant regime [inelastic electron (co)tunneling\n(IETS)]. We show that the interplay of these two processes leads to unexpected\nmirages of resonances not captured by either of the two pictures alone.\nAlthough this turns out to be important in a large fraction of the possible\nregimes of level positions and bias voltages, it has been given little\nattention in molecular transport studies. Combined with nonequilibrium IETS --\nfour-electron pump-probe excitations -- these mirages provide crucial\ninformation on the relaxation of spin excitations. Our encompassing physical\npicture is supported by a master-equation approach that goes beyond weak\ncoupling. The present work encourages the development of a broader connection\nbetween the fields of molecular quantum-dot and scanning probe spectroscopy."
    },
    {
        "anchor": "Achieving strongly negative scattering asymmetry factor in random media\n  composed of dual-dipolar particles: Understanding radiative transfer in random media like micro/nanoporous and\nparticulate materials, allows people to manipulate the scattering and\nabsorption of radiation, as well as opens new possibilities in applications\nsuch as imaging through turbid media, photovoltaics and radiative cooling. A\nstrong-backscattering phase function, i.e., a negative scattering asymmetry\nparameter $g$, is of great interest which can possibly achieve unusual\nradiative transport phenomena, for instance, Anderson localization of light.\nBased on the multipole expansion of Foldy-Lax equations and quasicrystalline\napproximation (QCA), we have rigorously derived analytical expressions for\neffective propagation constant and scattering phase function for a random\nsystem containing dual-dipolar particles, by taking the effect of structural\ncorrelations into account. Here we demonstrate that by utilizing structural\ncorrelations and the second Kerker condition for a disordered medium composed\nof randomly distributed silicon nanoparticles, a strongly negative scattering\nasymmetry factor ($g\\sim-0.5$) for multiple light scattering can be realized in\nthe near-infrared. As concentration of scattering particles rises, the\nbackscattering is also enhanced. Moreover, we show that in this circumstance,\ntransport mean free path is largely reduced and even smaller than that\npredicted by independent scattering approximation. We further explored the\ndependent scattering effects, including the modification of electric and\nmagnetic dipole excitations and far-field interference effect, both induced by\nthe structural correlations, for volume fraction of particles up to\n$f_v\\sim0.25$. Our results have profound implications in harnessing\nmicro/nanoscale radiative transfer through random media.",
        "positive": "Cotunneling renormalization in carbon nanotube quantum dots: We determine the level-shifts induced by cotunneling in a Coulomb blockaded\ncarbon nanotube quantum dot using leading order quasi-degenerate perturbation\ntheory within a single nanotube quartet. It is demonstrated that otherwise\ndegenerate and equally tunnel-coupled $K$ and $K'$ states are mixed by\ncotunneling and therefore split up in energy except at the\nparticle/hole-symmetric midpoints of the Coulomb diamonds. In the presence of\nan external magnetic field, we show that cotunneling induces a gate-dependent\n$g$-factor renormalization, and we outline different scenarios which might be\nobserved experimentally, depending on the values of both intrinsic $KK'$\nsplitting and spin-orbit coupling."
    },
    {
        "anchor": "Measuring carrier density in parallel conduction layers of quantum Hall\n  systems: An experimental analysis for two parallel conducting layers determines the\nfull resistivity tensor of the parallel layer, at magnetic fields where the\nother layer is in the quantum Hall regime. In heterostructures which exhibit\nparallel conduction in the modulation-doped layer, this analysis quantitatively\ndetermines the charge density in the doping layer and can be used to estimate\nthe mobility. To illustrate one application, experimental data show magnetic\nfreeze-out of parallel conduction in a modulation doped heterojunction. As\nanother example, the carrier density of a minimally populated second subband in\na two-subband quantum well is determined. A simple formula is derived that can\nestimate the carrier density in a highly resistive parallel layer from a single\nHall measurement of the total system.",
        "positive": "Quasiperiodic magnetic chain as a spin filter for arbitrary spin states: We show that a quasiperiodic magnetic chain comprising magnetic atomic sites\nsequenced in Fibonacci pattern can act as a prospective candidate for spin\nfilters for particles with arbitrary spin states. This can be achieved by\ntuning a suitable correlation between the amplitude of the substrate magnetic\nfield and the on-site potential of the magnetic sites, which can be controlled\nby an external gate voltage. Such correlation leads to a spin filtering effect\nin the system, allowing one of the spin components to completely pass through\nthe system while blocking the others over the allowed range of energies. The\nunderlying mechanism behind this phenomena holds true for particles with any\narbitrary spin states S = 1, 3/2, 2, . . ., in addition to the canonical case\nof spin-half particles. Our results open up the interesting possibility of\ndesigning a spin demultiplexer using a simple quasiperiodic magnetic chain\nsystem. Experimental realization of this theoretical study might be possible by\nusing ultracold quantum gases, and can be useful in engineering new spintronic\ndevices."
    },
    {
        "anchor": "Photon noise suppression by a built-in feedback loop: Visionary quantum photonic networks need transform-limited single photons on\ndemand. Resonance fluorescence on a quantum dot provides the access to a\nsolid-state single photon source, where the environment is unfortunately the\nsource of spin and charge noise that leads to fluctuations of the emission\nfrequency and destroys the needed indistinguishability. We demonstrate a\nbuilt-in stabilization approach for the photon stream, which relies solely on\ncharge carrier dynamics of a two-dimensional hole gas inside a micropillar\nstructure. The hole gas is fed by hole tunneling from field-ionized excitons\nand influences the energetic position of the excitonic transition by changing\nthe local electric field at the position of the quantum dot. The standard\ndeviation of the photon noise is suppressed by nearly 50 percent (noise power\nreduction of 6 dB) and it works in the developed micropillar structure for\nfrequencies up to 1 kHz. This built-in feedback loop represents an easy way for\nphoton noise suppression in large arrays of single photon emitters and promises\nto reach higher bandwidth by device optimization.",
        "positive": "Neutrality point of graphene with coplanar charged impurities: The ground-state and the transport properties of graphene subject to the\npotential of in-plane charged impurities are studied. The screening of the\nimpurity potential is shown to be nonlinear, producing a fractal structure of\nelectron and hole puddles. Statistical properties of this density distribution\nas well as the charge compressibility of the system are calculated in the\nleading-log approximation. The conductivity depends logarithmically on\n$\\alpha$, the dimensionless strength of the Coulomb interaction. The theory is\nasymptotically exact when $\\alpha$ is small, which is the case for graphene on\na substrate with a high dielectric constant."
    },
    {
        "anchor": "Unified Description of the Intrinsic Spin-Hall Effects: The intrinsic spin-Hall effects (SHE) in $p$-doped semiconductors [S.\nMurakami et al., Science 301, 1348 (2003)] and two-dimensional electron gases\nwith Rashba spin-orbit coupling [J. Sinova et al., Phys. Rev. Lett. 92, 126603\n(2004)] have been the subject of many theoretical studies, but their driving\nmechanisms have yet to be described in a unified manner. The former effect\narises from the adiabatic topological curvature of momentum space, from which\nholes acquire a spin-dependent anomalous velocity. The SHE in the Rashba\nsystem, on the other hand, results from the momentum-dependent spin dynamics in\nthe presence of an external electric field. The two effects clearly appear to\noriginate from distinct mechanisms. Our motivation for this article is to\naddress this apparent disparity and, in particular, to seek a unifying\ndescription of the effects. In this endeavor, we consider the explicit\ntime-dependence of SHE systems starting with a general spin-orbit model. We\nfind that by performing a gauge transformation of the general model with\nrespect to time, a well-defined gauge field appears in time space which has the\nphysical significance of an effective magnetic field. This magnetic field is\nshown to precisely account for the SHE in the Rashba system in the adiabatic\nlimit. Remarkably, by carefully analyzing the equation of motion of the general\nmodel, this field component is also found to be the origin of the anomalous\nvelocity due to the momentum space curvature. Our study therefore unifies the\ntwo seemingly disparate intrinsic SHEs under a common adiabatic framework.",
        "positive": "Multi-phonon relaxation and generation of quantum states in a nonlinear\n  mechanical oscillator: The dissipative quantum dynamics of an anharmonic oscillator is investigated\ntheoretically in the context of carbon-based nano-mechanical systems. In the\nshort-time limit, it is known that macroscopic superposition states appear for\nsuch oscillators. In the long-time limit, single and multi-phonon dissipation\nlead to decoherence of the non-classical states. However, at zero temperature,\nas a result of two-phonon losses the quantum oscillator eventually evolves into\na non-classical steady state. The relaxation of this state due to thermal\nexcitations and one-phonon losses is numerically and analytically studied. The\npossibility of verifying the occurrence of the non-classical state is\ninvestigated and signatures of the quantum features arising in a ring-down\nsetup are presented. The feasibility of the verification scheme is discussed in\nthe context of quantum nano-mechanical systems."
    },
    {
        "anchor": "Fractional focusing peaks and collective dynamics in two-dimensional\n  Fermi liquids: Carrier transport in materials is often diffusive due to momentum-relaxing\nscattering with phonons and defects. Suppression of momentum-relaxing\nscattering can lead to the ballistic and hydrodynamic transport regimes,\nwherein complex non-Ohmic current flow patterns, including current vortices,\ncan emerge. In the ballistic regime addressed here, transverse magnetic\nfocusing is habitually understood in a familiar single-particle picture of\ncarriers injected from a source, following ballistic cyclotron orbits and\nreaching a detector. We report on a distinctive nonlocal magnetoresistance\nphenomenon exclusive to fermions, in an enclosed mesoscopic geometry wherein\ntransverse focusing magnetoresistance peaks also occur at values of the\ncyclotron diameter that are incommensurate with the distance between the source\nand detector. In low-temperature experiments and simulations using GaAs/AlGaAs\nheterostructures with high electron mobility, we show that the peaks occur\nindependently of the location of the detector, and only depend on the\nsource-drain separation. We reproduce the experimental findings using\nsimulations of ballistic transport in both semiclassical and quantum-coherent\ntransport models. The periodicity of magnetic field at which the peaks occur is\nmatched to the lithographically defined device scale. It is found that, unlike\nin transverse magnetic focusing, the magnetoresistance structure cannot be\nattributed to any set of ordered single-particle trajectories but instead\nrequires accounting for the collective dynamics of the fermion distribution and\nof all particle trajectories. The magnetoresistance is further associated with\ncurrent flow vorticity, a collective phenomenon.",
        "positive": "Transport via classical percolation at quantum Hall plateau transitions: We consider transport properties of disordered two-dimensional electron gases\nunder high perpendicular magnetic field, focusing in particular on the peak\nlongitudinal conductivity $\\sigma_{xx}^\\mathrm{peak}$ at the quantum Hall\nplateau transition. We use a local conductivity model, valid at temperatures\nhigh enough such that quantum tunneling is suppressed, taking into account the\nrandom drift motion of the electrons in the disordered potential landscape and\ninelastic processes provided by electron-phonon scattering. A diagrammatic\nsolution of this problem is proposed, which leads to a rich interplay of\nconduction mechanisms, where classical percolation effects play a prominent\nrole. The scaling function for $\\sigma_{xx}^\\mathrm{peak}$ is derived in the\nhigh temperature limit, which can be used to extract universal critical\nexponents of classical percolation from experimental data."
    },
    {
        "anchor": "Shape tailoring to enhance and tune the properties of graphene\n  nanomechanical resonators: The shape of a nanomechanical resonator profoundly affects its mechanical\nproperties and determines its suitability for various applications, such as\nultra-sensitive mass and force detection. Despite the promise of\ntwo-dimensional nanomechanical systems in such applications, full control over\nthe shape of suspended two-dimensional materials, such as graphene, has not\nbeen achieved. We present an effective, single-step method to shape\npresuspended graphene into nanomechanical resonators with arbitrary geometries\nleading to enhanced properties in comparison to conventional drumheads. Our\ntechnique employs focused ion beam milling and achieves feature sizes ranging\nfrom a few tens of nanometers to several microns, while obtaining near perfect\nyield. We compare the mechanical properties of the shaped devices to unmodified\ndrumheads, and find that low-tension, singlyclamped graphene cantilevers\ndisplay a 20-fold increase in the mechanical quality factor (Q) with a factor\n100 reduction in the mechanical damping. Importantly, we achieve these results\nwhile simultaneously removing mass, which enables state-of-the-art force\nsensitivity for a graphene mechanical resonator at room temperature. Our\napproach opens up a unique, currently inaccessible regime in graphene\nnanomechanics, one characterized by low strain, low frequency, small mass, and\nhigh Q, and facilitates tailoring of non-linearity and damping in mechanical\nstructures composed of graphene and other 2D crystals.",
        "positive": "Eccentric Corbino FET in magnetic field: a highly tunable photodetector: We study gated field effect transistors (FETs) with an eccentric Corbino-disk\ngeometry, such that the drain spans its circumference while the off-center\ninner ring acts as a source. An AC THz potential difference is applied between\nsource and gate while a static source-drain voltage, rectified by the\nnonlinearities of FET electrons, is measured. When a magnetic field is applied\nperpendicular to the device, a strong resonance appears at the cyclotron\nfrequency. The strength of the resonance can be tuned by changing the\neccentricity of the disk. We show that there is an optimum value of the\neccentricity that maximizes the responsivity of the FET."
    },
    {
        "anchor": "The FIR-absorption of short period quantum wires and the transition from\n  one to two dimensions: We investigate the FIR-absorption of short period parallel quantum wires in a\nperpendicular quantizing magnetic field. The external time-dependent electric\nfield is linearly polarized along the wire modulation. The mutual Coulomb\ninteraction of the electrons is treated self-consistently in the ground state\nand in the absorption calculation within the Hartree approximation. We consider\nthe effects of a metal gate grating coupler, with the same or with a different\nperiod as the wire modulation, on the absorption. The evolution of the\nmagnetoplasmon in the nonlocal region where it is split into several Bernstein\nmodes is discussed in the transition from: narrow to broad wires, and isolated\nto overlapping wires. We show that in the case of narrow and not strongly\nmodulated wires the absorption can be directly correlated with the underlying\nelectronic bandstructure.",
        "positive": "Phonon-drag magnetoquantum oscillations in graphene: A theory of low-temperature phonon-drag magnetothermopower $S_{xx}^g$ is\npresented in graphene in a quantizing magnetic field. $S_{xx}^g$ is found to\nexhibit quantum oscillations as a function of magnetic field $B$ and electron\nconcentration $n_e$. Amplitude of the oscillations is found to increase\n(decrease) with increasing $B$ ($n_e$). The behavior of $S_{xx}^g$ is also\ninvestigated as a function of temperature. A large value of $S_{xx}^g $($\\sim$\nfew hundreds of $\\mu $V/K) is predicted. Numerical values of $S_{xx}^g $ are\ncompared with the measured magnetothermopower $S_{xx}$ and the diffusion\ncomponent $S_{xx}^d$ from the modified Girvin-Jonson theory."
    },
    {
        "anchor": "Preparation and tunable mid-IR optical properties of ternary\n  Cd_{1-x}Pb_xS nanocrystals by mechanical alloying: Composition-tunable ternary Cd1-xPbxS nanocrystals (NCs) are very important\nmaterials for remote sensing and detecting in the infrared (IR) wavelength\nregion. They are, however, almost exclusively prepared by wet chemical routes\nwhich leads to surface-capped nanoparticles. The surface capping molecules\ncould move their absorption peak from mid-IR to near IR wavelength region.\nHowever, surface clean Cd1-xPbxS nanocrystals (NCs) would demonstrate intrinsic\noptical spectrum in the mid-IR region. Herein, we present a physical mechanical\nalloying process being applied to prepare tens of grams of surface clean\nCd1-xPbxS nanocrystals within the composition range of x=0.5 to 1. The\nresulting nanocrystals have average sizes smaller than 9 nm, are chemically\nhomogenous, show a continuous lattice expansion with Pb content and a nonlinear\nband gap-composition relationship, demonstrating the ability to continuously\nand precisely tune the band gap energies of ternary Cd1-xPbxS semiconductor\nnanocrystals from mid-IR region (2638 nm) to NIR wavelength region (1059 nm)\nthrough chemical composition.",
        "positive": "Thermal Hall response: violation of gravitational analogues and Einstein\n  relations: The response of solids to temperature gradients is often described in terms\nof a gravitational analogue: the effect of a space-dependent temperature is\nmodeled using a space dependent metric. We investigate the validity of this\napproach in describing the bulk response of quantum Hall states and other\ngapped chiral topological states. To this end, we consider the prototypical\nHaldane model in two different cases of (i) a space-dependent electrostatic\npotential and gravitational potential and (ii) a space-dependent temperature\nand chemical potential imprinted by a weak coupling to non-interacting electron\nbaths and phonons. We find that the thermal analogue is \\textit{invalid}; while\na space dependent gravitational potential induces transverse energy currents\nproportional to the third derivative of the gravitational potential, the\nresponse to an analogous temperature profile vanishes in limit of weak coupling\nto the thermal bath. Similarly, the Einstein relation, the analogy between the\nelectrostatic potential and the internal chemical potential, is not valid in\nsuch a setup."
    },
    {
        "anchor": "Low temperature thermal properties of mesoscopic\n  normal-metal/superconductor heterostructures: Although the electrical transport properties of mesoscopic metallic samples\nhave been investigated extensively over the past two decades, the thermal\nproperties have received far less attention. This may be due in part to the\ndifficulty of performing thermal measurements on sub-micron scale samples. We\nreport here quantitative measurements of the thermal conductance and\nthermopower of a hybrid normal-metal/superconductor heterostructure, which are\nmade possible by the recent development of a local-thermometry technique. As\nwith electrical transport measurements, these thermal measurements reveal\nsignatures of the phase coherent nature of electron transport in these devices.",
        "positive": "Optical pump-probe studies of carrier dynamics in few-layer MoS2: Femtosecond optical pump-probe technique is used to study charge carrier\ndynamics in few-layer MoS2 samples fabricated by mechanical exfoliation. An\nultrafast pump pulse excites carriers and differential reflection of a probe\npulse tuned to an excitonic resonance is detected. We find that the spectrum of\nthe differential reflection signal is similar to the derivative of the\nresonance. The decay time of the signal is in the range of 150 to 400 ps,\nincreasing with the probe wavelength. With a fixed probe wavelength, the signal\nmagnitude is proportional to the pump fluence, while the decay time is\nindependent of it."
    },
    {
        "anchor": "Contact Induced Spin Relaxation in Graphene Spin Valves with Al2O3 and\n  MgO Tunnel Barriers: We investigate spin relaxation in graphene by systematically comparing the\nroles of spin absorption, other contact-induced effects (e.g. fringe fields,\netc.), and bulk spin relaxation for graphene spin valves with MgO barriers,\nAl2O3 barriers, and transparent contacts. We obtain effective spin lifetimes by\nfitting the Hanle spin precession data with two models that include or exclude\nthe effect of spin absorption. Results indicate that additional contact-induced\nspin relaxation other than spin absorption dominates the contact effect. For\ntunneling contacts, we find reasonable agreement between the two models with\nmedian discrepancy of ~20% for MgO and ~10% for Al2O3.",
        "positive": "Magnetic Quantum Oscillations of the Conductivity in Two-dimensional\n  Conductors with Localization: An analytic theory is developed for the diagonal conductivity $\\sigma_{xx}$\nof a 2D conductor which takes account of the localized states in the broaden\nLandau levels. In the low-field region $\\sigma_{xx}$ display the Shubnikov-de\nHaas oscillations which in the limit $\\Omega \\tau\\gg 1$ transforms into the\nsharp peaks ($\\Omega$ is the cyclotron frequency, $\\tau$ is the electron\nscattering time). Between the peaks $\\sigma_{xx}\\to 0$. With the decrease of\ntemperature, $T$, the peaks in $\\sigma_{xx}$ display first a thermal activation\nbehavior $\\sigma_{xx}\\propto \\exp(-\\Delta/T)$, which then crosses over into the\nvariable-range-hopping regime at lower temperatures with $\\sigma_{xx}\\propto\n1/T \\exp(-\\sqrt{T_{0}/T})$ (the prefactor 1/T is absent in the conductance)."
    },
    {
        "anchor": "Switching of Co magnetization driven by antiferromagnetic-ferromagnetic\n  phase transition of FeRh alloy in Co/FeRh bilayers: We show that Co spins in Co/FeRh epitaxial bilayers grown on W(110) switch\nreversibly between the two orthogonal in-plane directions as the FeRh layer\nundergoes temperature driven antiferromagnetic-ferromagnetic (AFM-FM) phase\ntransition. Switching of Co magnetization is characterized by a hysteretic\nbehavior owing to a temperature hysteresis of the AFM-FM transition in FeRh.\nThe spin reorientation of Co is driven by the evolution interfacial exchange\ncoupling to FeRh system across the AFM-FM process. Our results provide a new\nmethod of writing information purely by a local temperature change.",
        "positive": "Skyrmion Formation and Optical Spin-Hall Effect in an Expanding Coherent\n  Cloud of Indirect Excitons: We provide a theoretical description of the polarization pattern and phase\nsingularities experimentally evidenced recently in a condensate of indirect\nexcitons [H. High et al., Nature 483, 584-588 (2012)]. We show that the\naveraging of the electron and hole orbital motion leads to a comparable\nspin-orbit interaction for both type of carriers. We demonstrate that the\ninterplay between a radial coherent flux of bright indirect excitons and the\nDresselhaus spin-orbit interaction results in the formation of spin domains and\nof topological defects similar to Skyrmions. We reproduce qualitatively all the\nfeatures of the experimental data and obtain polarization pattern as in the\noptical spin Hall effect despite the different symmetry of the spin-orbit\ninteractions."
    },
    {
        "anchor": "Interacting Dirac fermions and the rise of Pfaffians in graphene: Fractional Quantum Hall effect (FQHE) is a unique many-body phenomenon, which\nwas discovered in a two-dimensional electron system placed in a strong\nperpendicular magnetic field. It is entirely due to the electron-electron\ninteractions within a given Landau level. For special filling factors of the\nLandau level, a many-particle incompressible state with a finite collective gap\nis formed. Among these states, when the Landau level is half filled, there is a\nspecial FQHE state that is described by the Pfaffian function and the state\nsupports charged excitations that obey non-Abelian statistics. Such a\n$1/2$-FQHE state can be realized only for a special profile of the\nelectron-electron potential. For example, for conventional electron systems,\nthe $1/2$-FQHE state occurs only in the second Landau level, while in a\ngraphene monolayer, no $1/2$-FQHE state can be found in any Landau level.\nAnother type of low-dimensional system is the bilayer graphene, which consists\nof two graphene monolayers coupled through the inter-layer hopping. The system\nis quasi-two-dimensional, which makes it possible to tune the inter-electron\ninteraction potential by applying either the bias voltage or the magnetic field\nthat is applied parallel to the bilayer. It so happens that in the bilayer\ngraphene with AB staking, there is one Landau level per valley where the\n$1/2$-FQHE state can indeed be present. The properties of that $1/2$-FQHE state\nhave a nonmonotonic dependence on the applied magnetic field and this can be\neven more stable than the one discovered in conventional electron systems.",
        "positive": "Topological Localized Modes In Moir\u00e9 Lattices of Bilayer Elastic\n  Plates With Resonators: We investigate the existence of higher order topological localized modes in\nmoir\\'{e} lattices of bilayer elastic plates. Each plate has a hexagonal array\nof discrete resonators and one of the plates is rotated an angle\n($21.78^\\circ$) which results in a periodic moir\\'{e} lattice with the smallest\narea. The two plates are then coupled by inter-layer springs at discrete\nlocations where the top and bottom plate resonators coincide. Dispersion\nanalysis using the plane wave expansion method reveals that a bandgap opens on\nadding the inter-layer springs. The corresponding topological index, namely\nfractional corner mode, for bands below the bandgap predicts the presence of\ncorner localized modes in a finite structure. Numerical simulations of\nfrequency response show localization at all corners, consistent with the\ntheoretical predictions. The considered continuous elastic bilayered moir\\'{e}\nstructures opens opportunities for novel wave phenomena, with potential\napplications in tunable energy localization and vibration isolation."
    },
    {
        "anchor": "Recursive Diagonalization of Quantum Hamiltonians to all order in\n  $\\hbar$: We present a diagonalization method for generic matrix valued Hamiltonians\nbased on a formal expansion in power of $\\hbar $. Considering $\\hbar $ as a\nrunning parameter, a differential equation connecting two diagonalization\nprocesses for two very close values of $\\hbar $ is derived. The integration of\nthis differential equation allows the recursive determination of the series\nexpansion in powers of $\\hbar $ for the diagonalized Hamiltonian. This approach\nresults in effective Hamiltonians with Berry phase corrections of higher order\nin $\\hbar $, and deepens previous works on the semiclassical diagonalization of\nquantum Hamiltonians which led notably to the discovery of the intrinsic spin\nHall effect. As physical applications we consider spinning massless particles\nin isotropic inhomogeneous media and show that both the energy and the velocity\nget quantum corrections of order $\\hbar ^{2}$. We also derive formally to all\norder in $\\hbar $ the energy spectrum and the equations of motion of Bloch\nelectrons in an external electric field.",
        "positive": "Tailoring the dielectric screening in WS$_2$-graphene heterostructures: The environment contributes to the screening of Coulomb interactions in\ntwo-dimensional semiconductors. This can potentially be exploited to tailor\nmaterial properties as well as for sensing applications. Here, we investigate\nthe tuning of the band gap and the exciton binding energy in the\ntwo-dimensional semiconductor WS$_2$ via the external dielectric screening.\nEmbedding WS$_2$ in van der Waals heterostructures with graphene and hBN\nspacers of thicknesses between one and 16 atomic layers, we experimentally\ndetermine both energies as a function of the \\WS-to-graphene interlayer\ndistance. We find that the modification to the band gap as well as the exciton\nbinding energy are well described by a one-over-distance dependence, with a\nsignificant effect remaining at several nm distance, at which the two layers\nare electrically well isolated. This observation is explained by a screening\narising from an image charge induced by the graphene layer. Furthermore, we\nfind that the effectiveness of graphene to screen Coulomb interactions in\nnearby WS$_2$ depends on its doping level and can therefore be controlled via\nthe electric field effect. We determine that, at room temperature, it is\nmodified by approximately 20\\% for charge carrier densities of $2\\times10^{12}$\ncm$^{-2}$."
    },
    {
        "anchor": "Anomalous Cherenkov spin-orbit sound: The Cherenkov effect is a well known phenomenon in the electrodynamics of\nfast charged particles passing through transparent media. If the particle is\nfaster than the light in a given medium, the medium emits a forward light cone.\nThis beautiful phenomenon has an acoustic counterpart where the role of photons\nis played by phonons and the role of the speed of light is played by the sound\nvelocity. In this case the medium emits a forward sound cone. Here, we show\nthat in a system with spin-orbit interactions in addition to this {\\it normal}\nCherenkov sound there appears an {\\it anomalous} Cherenkov sound with forward\nand {\\it backward} sound propagation. Furthermore, we demonstrate that the\ntransition from the normal to anomalous Cherenkov sound happens in a {\\it\nsingular} way at the Cherenkov cone angle. The detection of this acoustic\nsingularities therefore represents an alternative experimental tool for the\nmeasurement of the spin-orbit coupling strength.",
        "positive": "Quantum Noise in the Electromechanical Shuttle: We consider a type of Quantum Electro-Mechanical System, known as the shuttle\nsystem, first proposed by Gorelik et al., [Phys. Rev. Lett., 80, 4526, (1998)].\nWe use a quantum master equation treatment and compare the semi-classical\nsolution to a full quantum simulation to reveal the dynamics, followed by a\ndiscussion of the current noise of the system. The transition between\ntunnelling and shuttling regime can be measured directly in the spectrum of the\nnoise."
    },
    {
        "anchor": "Transport through vertical graphene contacts under intense laser fields: We theoretically study the electronic and transport properties of two\ngraphene layers vertically coupled by an insulating layer under the influence\nof a time-periodic external light field. The non-adiabatic driving induces\nexcitations of electrons and a redistribution of the occupied states which is\nmanifested in the opening of gaps in the quasienergy spectrum of graphene. When\na voltage is applied between the top and bottom graphene layers, the\nphoto-induced nonequilibrium occupation modifies the transport properties of\nthe contact. We investigate the electronic and transport properties of the\ncontact by using the nonequilibrium Green's function formalism. To illustrate\nthe behavior of the differential conductance of the vertical contact under the\nlight illumination, we consider two cases. First, we assume that both the\nbottom and top layers consist of graphene and second we consider a finite mass\nterm in the bottom layer. We obtain that the differential conductance is\nstrongly suppressed due to the opening of gaps in the quasienergy spectrum in\ngraphene. Additionally, the conductance shows features corresponding to the\ntunneling of photoexcited electrons at energies of the van Hove singularity for\nboth the top and bottom layers. In the case of a finite mass term in the bottom\nlayer, the differential conductance can be directly related to the tunneling of\nphotoexcited electrons.",
        "positive": "Dark-bright mixing of interband transitions in symmetric semiconductor\n  quantum dots: In photoluminescence spectra of symmetric [111] grown GaAs/AlGaAs quantum\ndots in longitudinal magnetic fields applied along the growth axis we observe\nin addition to the expected bright states also nominally dark transitions for\nboth charged and neutral excitons. We uncover a strongly non-monotonous, sign\nchanging field dependence of the bright neutral exciton splitting resulting\nfrom the interplay between exchange and Zeeman effects. Our theory shows\nquantitatively that these surprising experimental results are due to\nmagnetic-field-induced \\pm 3/2 heavy-hole mixing, an inherent property of\nsystems with C_3v point-group symmetry."
    },
    {
        "anchor": "Observation of intrinsic inverse spin Hall effect: We report observation of intrinsic inverse spin Hall effect in un-doped GaAs\nmultiple quantum wells with a sample temperature of 10 K. A transient ballistic\npure spin current is injected by a pair of laser pulses through quantum\ninterference. By time-resolving the dynamics of the pure spin current, the\nmomentum relaxation time is deduced, which sets the lower limit of the\nscattering time between electrons and holes. The transverse charge current\ngenerated by the pure spin current via the inverse spin Hall effect is\nsimultaneously resolved. We find that the charge current is generated well\nbefore the first electron-hole scattering event. Generation of the transverse\ncurrent in the scattering-free ballistic transport regime provides unambiguous\nevidence for the intrinsic inverse spin Hall effect.",
        "positive": "Spatially Resolved Sensing in Microfluidics with Multimode Microwave\n  Resonators: The analogy between mechanical and electromagnetic resonators has been a\ncelebrated paradigm of science and engineering. Exploration of this analogy in\nrecent years has resulted in several exciting research directions, including\ncavity optomechanics[1], phononic bandgap materials[2] and phononic\nmetamaterials[3-5]. In these examples, progress in electromagnetic research has\nusually led the way for their mechanical counterparts. Here, we contribute to\nthis analogy from a different perspective by adapting a sensing technique\noriginally developed for mechanical devices to increase the capabilities of\nsensors based on electromagnetic fields. More specifically, multimode resonance\ntechniques, which enable spatial resolution in inertial mass sensing\nexperiments with nanoelectromechanical systems (NEMS), are tailored for use in\nmicrowave resonant sensing, which is commonly employed in microfluidics. We\nshow that the use of higher-order modes of such sensors can provide electrical\nvolume, position and geometric size data. The combination of such spatial\nfeatures implies the potential for image reconstruction when a large number of\nmodes are used. With the analytical and experimental framework presented here,\nwe can move beyond simple counting and achieve the sizing and imaging of\nanalytes with impedance spectroscopy."
    },
    {
        "anchor": "Adsorbate Transport on Graphene by Electromigration: Chemical functionalization of graphene holds promise for various applications\nranging from nanoelectronics to catalysis, drug delivery, and nanoassembly. In\nmany applications it is important to be able to transport adsorbates on\ngraphene in real time. We propose to use electromigration to drive the\nadsorbate transport across the graphene sheet. To assess the efficiency of\nelectromigration, we develop a tight-binding model of electromigration of an\nadsorbate on graphene and obtain simple analytical expressions for different\ncontributions to the electromigration force. Using experimentally accessible\nparameters of realistic graphene-based devices as well as electronic structure\ntheory calculations to parametrize the developed model, we argue that\nelectromigration on graphene can be efficient. As an example, we show that the\ndrift velocity of atomic oxygen covalently bound to graphene can reach ~1 cm/s.",
        "positive": "Quantum point contact as a probe of a topological superconductor: We calculate the conductance of a ballistic point contact to a\nsuperconducting wire, produced by the s-wave proximity effect in a\nsemiconductor with spin-orbit coupling in a parallel magnetic field. The\nconductance G as a function of contact width or Fermi energy shows plateaus at\nhalf-integer multiples of 4e^2/h if the superconductor is in a topologically\nnontrivial phase. In contrast, the plateaus are at the usual integer multiples\nin the topologically trivial phase. Disorder destroys all plateaus except the\nfirst, which remains precisely quantized, consistent with previous results for\na tunnel contact. The advantage of a ballistic contact over a tunnel contact as\na probe of the topological phase is the strongly reduced sensitivity to finite\nvoltage or temperature."
    },
    {
        "anchor": "Origin of Low-Frequency Negative Transconductance Dispersion in p-HEMT: Measurements of low-frequency transconductance dispersion at different\ntemperatures and conductance deep level transient spectroscopic(CDLTS) studies\nof an AlGaAs/InGaAs pseudomorphic HEMT were carried out. The experimental\nresults show the presence of defect states at the AlGaAs/InGaAs\nhetero-interface. A mobility degradation model was developed to explain the low\nfrequency negative transconductance dispersion as well as the apparent\nhole-like peaks observed in the CDLTS spectra. This model incorporates a time\ndependent change in 2DEG mobility due to ionised impurity scattering by the\nremaining charge states at the adjoining AlGaAs/InGaAs hetero-interface.",
        "positive": "Conserved current of nonconserved quantities: We provide a unified semiclassical theory for the conserved current of\nnonconserved quantities, and manifest it in two physical contexts: the spin\ncurrent of Bloch electrons and the charge current of mean-field Bogoliubov\nquasiparticles. Several longstanding problems that limit the playground of the\nconserved spin current of electrons are solved. We reveal that the hitherto\noverlooked torque quadrupole density and Berry phase correction to the torque\ndipole density are essential to assure a circulating spin current with\nvanishing net flow at equilibrium. The band geometric origin of bulk spin\ntransport is ascertained to be the momentum space spin texture and Berry\ncurvature instead of the spin Berry curvature, paving the way for material\nrelated studies. In superconductors the attained conserved charge current\ncorresponds to the quasiparticle charge current renormalized by the condensate\nbackflow. Its circulation at equilibrium gives an orbital magnetization, which\ninvolves the characteristics of superconductivity, such as the Berry curvature\narising from unconventional pairing and an orbital magnetic moment induced by\nthe charge dipole of moving quasiparticles."
    },
    {
        "anchor": "Collective magnetic response of CeO2 nanoparticles: The magnetism of nanoparticles and thin films of wide-bandgap oxides that\ninclude no magnetic cations is an unsolved puzzle. Progress has been hampered\nboth by the irreproducibility of much of the experimental data, and the lack of\nany generally-accepted theoretical explanation. The characteristic signature is\na virtually anhysteretic, temperature-independent magnetization curve which\nsaturates in an applied field that is several orders of magnitude greater than\nthe magnetization. It appears as if a tiny volume fraction, < 0.1%, of the\nsamples is magnetic and that the energy scale of the problem is unusually high\nfor spin magnetism. Here we investigate the effect of dispersing 4 nm CeO2\nnanoparticles with powders of gamma-Al2O3, sugar or latex microspheres. The\nsaturation magnetization, Ms ~ 60 A/m for compact samples, is maximized by 1\nwt% lanthanum doping. Dispersing the CeO2 nanopowder reduces its magnetic\nmoment by up to an order of magnitude. There is a characteristic length scale\nof order 100 nm for the magnetism to appear in CeO2 nanoparticle clusters. The\nphenomenon is explained in terms of a giant orbital paramagnetism that appears\nin coherent mesoscopic domains due to resonant interaction with zero-point\nfluctuations of the vacuum electromagnetic field. The theory explains the\nobserved temperature-independent magnetization curve and its doping and\ndispersion dependence, based on a length scale of 300 nm that corresponds to\nthe wavelength of a maximum in the UV absorption spectrum of the magnetic CeO2\nnanoparticles. The coherent domains occupy roughly ten percent of the sample\nvolume.",
        "positive": "Band splitting and Weyl nodes in trigonal tellurium studied by\n  angle-resolved photoemission spectroscopy and density functional theory: We have performed high-resolution angle-resolved photoemission spectroscopy\n(ARPES) on trigonal tellurium consisting of helical chains in the crystal.\nThrough the band-structure mapping in the three-dimensional Brillouin zone, we\nfound a definitive evidence for the band splitting originating from the chiral\nnature of crystal. A direct comparison of the band dispersion between the ARPES\nresults and the first-principles band-structure calculations suggests the\npresence of Weyl nodes and tiny spin-polarized hole pockets around the H point.\nThe present result opens a pathway toward studying the interplay among crystal\nsymmetry, band structure, and exotic physical properties in chiral crystals."
    },
    {
        "anchor": "Tailoring photon emission patterns in nanostructures: We investigate the photon emission in coupled quantum dots based on symmetry\nconsiderations. With the help of a new theorem we proved, we reveal the origin\nof the various emission patterns, which is the combinative symmetry in the time\ndomain and spectrum domain. We are able to tailor the emission patterns and\nobtain emission spectra with odd harmonics only, even harmonics only, both odd\nand even harmonic components, or even the quenching of all components. These\ninteresting emission patterns can be obtained in experiments by careful design\nof the nanostructures, which are of many applications in optical-electric\nnanodevices.",
        "positive": "Current-driven periodic domain wall creation in ferromagnetic nano-wires: We predict the electrical generation and injection of domain walls into a\nferromagnetic nano-wire without the need of an assisting magnetic field. Our\nanalytical and numerical results show that above a critical current $j_{c}$\ndomain walls are injected into the nano-wire with a period $T \\sim\n(j-j_{c})^{-1/2}$. Importantly, domain walls can be produced periodically even\nin a simple exchange ferromagnet with uniaxial anisotropy, without requiring\nany standard \"twisting\" interaction like Dzyaloshinskii-Moriya or dipole-dipole\ninteractions. We show analytically that this process and the period exponents\nare universal and do not depend on the peculiarities of the microscopic\nHamiltonian. Finally we give a specific proposal for an experimental\nrealization."
    },
    {
        "anchor": "Effects of edge chemistry doping on graphene nanoribbon mobility: Doping of semiconductor is necessary for various device applications.\nExploiting chemistry at its reactive edges was shown to be an effective way to\ndope an atomically thin graphene nanoribbon (GNR) for realizing new devices in\nrecent experiments. The carrier mobility limited by edge doping is studied as a\nfunction of the GNR width, doping density, and carrier density by using ab\ninitio density functional and parameterized tight binding simulations combined\nwith the non-equilibrium Green's function formalism for quantum transport. The\nresults indicate that for GNRs wider than about 4nm, the mobility scales\napproximately linearly with the GNR width, inversely proportional to the edge\ndoping concentration and decreases for an increasing carrier density. For\nnarrower GNRs, dependence of the mobility on the GNR width and carrier density\ncan be qualitatively different.",
        "positive": "Josephson current through interacting double quantum dots with\n  spin-orbit coupling: We study the effect of Rashba spin-orbit interaction on the Josephson current\nthrough a double quantum dot in presence of Coulomb repulsion. In particular,\nwe describe the characteristic effects on the magnetic-field induced\nsinglet-triplet transition in the molecular regime. Exploring the whole\nparameter space, we analyze the effects of the device asymmetry, the\norientation of the applied magnetic field with respect to the spin-orbit\ninteraction, and finite temperatures. We find that at finite temperatures the\northogonal component of the spin-orbit interaction exhibits a similar effect as\nthe Coulomb interaction inducing the occurrence of a {\\pi}-phase at\nparticle-hole symmetry. This provides a new route to the experimental\nobservability of the {\\pi}-phase in multi-level quantum dots."
    },
    {
        "anchor": "Universality in the transport response of molecular wires physisorbed\n  onto graphene electrodes: We analyze the low-voltage transport response of large molecular wires\nbridging graphene electrodes, where the molecules are physisorbed onto the\ngraphene sheets by planar anchor groups. In our study, the sheets are pulled\naway to vary the gap length and the relative atomic positions. The molecular\nwires are also translated in directions parallel and perpendicular to the\nsheets. We show that the energy position of the Breit-Wigner molecular\nresonances is universal for a given molecule, in the sense that it is\nindependent of the details of the graphene edges, gaps lengths or of the\nmolecule positions. We discuss the need to converge carefully the k-sampling to\nprovide reasonable values of the conductance.",
        "positive": "Modeling charge relaxation in graphene quantum dots induced by\n  electron-phonon interaction: We study and compare two analytic models of graphene quantum dots for\ncalculating charge relaxation times due to electron-phonon interaction.\nRecently, charge relaxation processes in graphene quantum dots have been probed\nexperimentally and here we provide a theoretical estimate of relaxations times.\nBy comparing a model with pure edge confinement to a model with electrostatic\nconfinement, we find that the latter features much larger relaxation times.\nInterestingly, relaxation times in electrostatically defined quantum dots are\npredicted to exceed the experimentally observed lower bound of ~100 ns."
    },
    {
        "anchor": "Locality of the anomalous Hall conductivity: The geometrical intrinsic contribution to the anomalous Hall conductivity\n(AHC) of a metal is commonly expressed as a reciprocal-space integral: as such,\nit only addresses unbounded and macroscopically homogeneous samples. Here we\nshow that the geometrical AHC has an equivalent expression as a local property.\nWe define a \"geometrical marker\" which actually probes the AHC in inhomogeneous\nsystems (e.g. heterojunctions), as well as in bounded samples. The marker may\neven include extrinsic contributions of geometrical nature.",
        "positive": "Fidelity of optically induced single-spin rotations in semiconductor\n  quantum dots in the presence of nuclear spins: We examine the influence of nuclear spins on the performance of optically\ninduced rotations of single electron spins in semiconductor quantum dots. We\nconsider Raman type optical transitions between electron spin states and take\ninto account the additional effect of the Overhauser field. We calculate\naverage fidelities of rotations around characteristic axes in the presence of\nnuclear spins analytically with perturbation theory up to second order in the\nOverhauser field. Moreover, we calculate the fidelity using numerical averaging\nover the nuclear field distribution, including arbitrary orders of the\nhyperfine interaction."
    },
    {
        "anchor": "Methane as an effective hydrogen source for single-layer graphene\n  synthesis on Cu foil by plasma enhanced chemical vapor deposition: A single-layer graphene is synthesized on Cu foil in the absence of H2 flow\nby plasma enhanced chemical vapor deposition (PECVD). In lieu of an explicit H2\nflow, hydrogen species are produced during methane decomposition process into\ntheir active species (CHx<4), assisted by the plasma. Notably, the early stage\nof growth depends strongly on the plasma power. The resulting grain size (the\nnucleation density) has a maximum (minimum) at 50 W and saturates when the\nplasma power is higher than 120 W because hydrogen partial pressures are\neffectively tuned by a simple control of the plasma power. Raman spectroscopy\nand transport measurements show that decomposed methane alone can provide\nsufficient amount of hydrogen species for high-quality graphene synthesis by\nPECVD.",
        "positive": "Atomistic $T$-matrix theory of disordered 2D materials: Bound states,\n  spectral properties, quasiparticle scattering, and transport: In this work, we present an atomistic first-principles framework for modeling\nthe low-temperature electronic and transport properties of disordered\ntwo-dimensional (2D) materials with randomly distributed point defects\n(impurities). The method is based on the $T$-matrix formalism in combination\nwith realistic density-functional theory (DFT) descriptions of the defects and\ntheir scattering matrix elements. From the $T$-matrix approximations to the\ndisorder-averaged Green's function (GF) and the collision integral in the\nBoltzmann transport equation, the method allows calculations of, e.g., the\ndensity of states (DOS) including contributions from bound defect states, the\nquasiparticle spectrum and the spectral linewidth (scattering rate), and the\nconductivity/mobility of disordered 2D materials. We demonstrate the method by\nexamining these quantities in monolayers of the archetypal 2D materials\ngraphene and transition metal dichalcogenides (TMDs) contaminated with vacancy\ndefects and substitutional impurity atoms. By comparing the Born and $T$-matrix\napproximations, we also demonstrate a strong breakdown of the Born\napproximation for defects in 2D materials manifested in a pronounced\nrenormalization of, e.g., the scattering rate by the higher-order $T$-matrix\nmethod. As the $T$-matrix approximation is essentially exact for dilute\ndisorder, i.e., low defect concentrations ($c_\\text{dis} \\ll 1$) or density\n($n_\\text{dis}\\ll A_\\text{cell}^{-1}$ where $A_\\text{cell}$ is the unit cell\narea), our first-principles method provides an excellent framework for modeling\nthe properties of disordered 2D materials with defect concentrations relevant\nfor devices."
    },
    {
        "anchor": "The current polarization rectification of the integer quantized Hall\n  effect: We report on our theoretical investigation considering the widths of\nquantized Hall plateaus (QHPs) depending on the density asymmetry induced by\nthe large current within the out-of-linear response regime. We solve the\nSchrodinger equation within the Hartree type mean field approximation using\nThomas Fermi Poisson nonlinear screening theory. We observe that the two\ndimensional electron system splits into compressible and incompressible regions\nfor certain magnetic field intervals, where the Hall resistance is quantized\nand the longitudinal resistance vanishes, if an external current is imposed. We\nfound that the strong current imposed, induces an asymmetry on the IS width\ndepending linearly on the current intensity.",
        "positive": "Uncovering nonperturbative dynamics of the biased sub-Ohmic spin-boson\n  model with variational Matrix Product States: We study the dynamics of the biased sub-Ohmic spin-boson model by means of a\ntime-dependent variational matrix product state (TDVMPS) algorithm. The\nevolution of both the system and the environment is obtained in the weak- and\nthe strong-coupling regimes, respectively characterized by damped spin\noscillations and by a nonequilibrium process where the spin freezes near its\ninitial state, which are explicitly shown to arise from a variety of reactive\nenvironmental quantum dynamics. We also explore the rich phenomenology of the\nintermediate-coupling case, a nonperturbative regime where the system shows a\ncomplex dynamical behavior, combining features of both the weakly and the\nstrongly coupled case in a sequential, time-retarded fashion. Our work\ndemonstrates the potential of TDVMPS methods for exploring otherwise elusive,\nnonperturbative regimes of complex open quantum systems, and points to the\npossibilities of exploiting the qualitative, real-time modification of quantum\nproperties induced by nonequilibrium bath dynamics in ultrafast transient\nprocesses."
    },
    {
        "anchor": "Incidence of Quantum Confinement on Dark Triplet Excitons in Carbon\n  Nanotubes: Photophysics of single-wall carbon nanotubes (SWCNTs) is intensively studied\ndue to their potential application in light harvesting and optoelectronics.\nExcited states of SWCNTs form strongly bound electron-hole pairs, excitons, of\nwhich only singlet excitons participate in application relevant optical\ntransitions. Long-living spin-triplet states hinder applications but they\nemerge as candidates for quantum information storage. Therefore knowledge of\nthe triplet exciton energy structure, in particular in a SWCNT chirality\ndependent manner, is greatly desired. We report the observation of light\nemission from triplet state recombination, i.e. phosphorescence, for several\nSWCNT chiralities using a purpose-built spectrometer. This yields the\nsinglet-triplet gap as a function of SWCNT diameter and it follows predictions\nbased on quantum confinement effects. Saturation under high microwave power (up\nto 10 W) irradiation allows to determine the spin-relaxation time for triplet\nstates. Our study sensitively discriminates whether the lowest optically active\nstate is populated from an excited state on the same nanotube or through\nF\\\"orster exciton energy transfer from a neighboring nanotube.",
        "positive": "Double island Coulomb blockade in (Ga,Mn)As-nanoconstrictions: We report on a systematic study of the Coulomb blockade effects in\nnanofabricated narrow constrictions in thin (Ga,Mn)As films. Different\nlow-temperature transport regimes have been observed for decreasing\nconstriction sizes: the ohmic, the single electron tunnelling (SET) and a\ncompletely insulating regime. In the SET, complex stability diagrams with\nnested Coulomb diamonds and anomalous conductance suppression in the vicinity\nof charge degeneracy points have been observed. We rationalize these\nobservations in the SET with a double ferromagnetic island model coupled to\nferromagnetic leads. Its transport characteristics are analyzed in terms of a\nmodified orthodox theory of Coulomb blockade which takes into account the\nenergy dependence of the density of states in the metallic islands."
    },
    {
        "anchor": "Reproducing topological properties with quasi-Majorana states: Andreev bound states in hybrid superconductor-semiconductor devices can have\nnear-zero energy in the topologically trivial regime as long as the confinement\npotential is sufficiently smooth. These quasi-Majorana states show zero-bias\nconductance features in a topologically trivial phase, mimicking spatially\nseparated topological Majorana states. We show that in addition to the\nsuppressed coupling between the quasi-Majorana states, also the coupling of\nthese states across a tunnel barrier to the outside is exponentially different\nfor increasing magnetic field. As a consequence, quasi-Majorana states mimic\nmost of the proposed Majorana signatures: quantized zero-bias peaks, the $4\\pi$\nJosephson effect, and the tunneling spectrum in presence of a normal quantum\ndot. We identify a quantized conductance dip instead of a peak in the open\nregime as a distinguishing feature of true Majorana states in addition to\nhaving a bulk topological transition. Because braiding schemes rely only on the\nability to couple to individual Majorana states, the exponential control over\ncoupling strengths allows to also use quasi-Majorana states for braiding.\nTherefore, while the appearance of quasi-Majorana states complicates the\nobservation of topological Majorana states, it opens an alternative route\ntowards braiding of non-Abelian anyons and protected quantum computation.",
        "positive": "Thresholdless Coherent Light Scattering from Subband-polaritons in a\n  Strongly-Coupled Microcavity: We study a \"strongly-coupled\" (SC) polariton system formed between the\natom-like intersubband transitions in a semiconductor nanostructure and the THz\noptical modes that are localised at the edges of a gold aperture. The\npolaritons can be excited optically, by incoherent excitation with bandgap\nradiation, and we find that they also coherently scatter the same input laser,\nto give strikingly sharp \"sideband\" (SB) spectral peaks in the backscattered\nspectrum. The SB intensity is a sensitive track of the polariton density and\nthey can be detected down to a quantum noise floor that is more than 2500 times\nlower than the excitation thresholds of comparable quantum cascade laser\ndiodes. Compared with other coherent scattering mechanisms, higher order SB\nscattering events are readily observable, and we speculate that the effect may\nfind utility as a passive all-optical wavelength shifting mechanism in\ntelecommunications systems."
    },
    {
        "anchor": "Surface impedance and topologically protected interface modes in\n  one-dimensional phononic crystals: When semi-infinite phononic crystals (PCs) are in contact, localized modes\nmay exist at their boundary. The central question is generally to predict their\nexistence and to determine their stability. With the rapid expansion of the\nfield of topological insulators, powerful tools have been developed to address\nthese questions. In particular, when applied to one-dimensional systems with\nmirror symmetry, the bulk-boundary correspondence claims that the existence of\ninterface modes is given by a topological invariant computed from the bulk\nproperties of the phononic crystal, which ensures strong stability properties.\nThis one-dimensional bulk-boundary correspondence has been proven in various\nworks. Recent attempts have exploited the notion of surface impedance, relying\non analytical calculations of the transfer matrix. In the present work, the\nmonotonic evolution of surface impedance with frequency is proven for all\none-dimensional phononic crystals with mirror symmetry. This result allows us\nto establish a stronger version of the bulk-boundary correspondence that\nguarantees not only the existence but also the uniqueness of a topologically\nprotected interface state. The method is numerically illustrated in the\nphysically relevant case of PCs with imperfect interfaces, where analytical\ncalculations would be out of reach.",
        "positive": "General analytical solution to exact fermion master equation: The exact fermion master equation previously obtained in [Phys. Rev. B\n\\textbf{78}, 235311 (2008); New J. Phys. \\textbf{12}, 083013 (2010)] describes\nthe dynamics of quantum states of a principal system of fermionic particles\nunder the influences of external fermion reservoirs (e.g. nanoelectronic\nsystems). Here, we present the general solution to this exact fermion master\nequation. The solution is analytically expressed in the most intuitive particle\nnumber representation. It is applicable to an arbitrary number of orbitals in\nthe principal system prepared at arbitrary initial states. We demonstrate the\nusefulness of such general solution with the transient dynamics of\nnanostructured artificial molecules. We show how various initial states can\nlead to distinct transient dynamics, manifesting a multitude of underlying\ntransition pathways."
    },
    {
        "anchor": "Topological states of non-Dirac electrons on triangular lattice: We demonstrate the possibility of topological states for non-Dirac electrons.\nSpecifically it is shown that, because of the $C_{\\rm 3}$ crystal symmetry and\ntime reversal symmetry, $p_x$ and $p_y$ orbits accommodated on triangular\nlattice exhibit a quadratic band touching at $\\Gamma$ point at the Fermi level.\nWhen the atomic spin-orbit coupling (SOC) is taken into account, a gap is\nopened resulting in a quantum spin Hall effect state. As revealed explicitly by\na $k\\cdot p$ model, the topology is associated with a meron structure in the\npseudo spin texture with vorticity two, a mechanism different from honeycomb\nlattice and the band inversion. One possible realization of this scheme is the\n1/3 coverage by Bi atom adapted on the Si[111] surface. First-principle\ncalculations are carried out, and a global gap of $\\sim 0.15$eV is observed.\nWith the Si substrate taking part in realizing the nontrivial topology, the\npresent template is expected to make the integration of topological states into\nexisting electronics and photonics technologies promising.",
        "positive": "Site-Selective Field Emission Source by Femtosecond Laser Pulses and Its\n  Emission Mechanism: Recent experimental and theoretical investigations on asymmetric field\nemission induced by weak femtosecond laser pulses and also its emission\nmechanisms are briefly reviewed. The emission mechanisms are discussed further\nfor a wider range of DC fields and laser power. It appears that firstly\nphoto-assisted field emission from lower-excitation order grows in the higher\nDC fields and secondly our simulations can be applied only for lower laser\npower."
    },
    {
        "anchor": "Fermi-arc metals: We predict a novel metallic state of matter that emerges in a Weyl-semimetal\nsuperstructure with spatially varying Weyl-node positions. In the new state,\nthe Weyl nodes are stretched into extended, anisotropic Fermi surfaces, which\ncan be understood as being built from Fermi arc-like states. This \"Fermi-arc\nmetal\" exhibits the chiral anomaly of the parental Weyl semimetal. However,\nunlike in the parental Weyl semimetal, in the Fermi-arc metal the\n\"ultra-quantum state\", in which the anomalous chiral Landau level is the only\nstate at the Fermi energy, is already reached for a finite energy window at\nzero magnetic field. The dominance of the ultra-quantum state implies a\nuniversal low-field ballistic magnetoconductance and the absence of quantum\noscillations, making the Fermi surface \"invisible\" to de Haas-van Alphen and\nShubnikov-de Haas effects, although it signifies its presence in other response\nproperties.",
        "positive": "Correlation-induced valley topology in buckled graphene superlattices: Flat bands emerging in buckled monolayer graphene superlattices have been\nrecently shown to realize correlated states analogous to those observed in\ntwisted graphene multilayers. Here, we demonstrate the emergence of valley\ntopology driven by competing electronic correlations in buckled graphene\nsuperlattices. We show, both by means of atomistic models and a low-energy\ndescription, that the existence of long-range electronic correlations leads to\na competition between antiferromagnetic and charge density wave instabilities,\nthat can be controlled by means of screening engineering. Interestingly, we\nfind that the emergent charge density wave has a topologically non-trivial\nelectronic structure, leading to a coexistent quantum valley Hall insulating\nstate. In a similar fashion, the antiferromagnetic phase realizes a\nspin-polarized quantum valley-Hall insulating state. Our results put forward\nbuckled graphene superlattices as a new platform to realize interaction-induced\ntopological matter."
    },
    {
        "anchor": "Broadband Quantum Efficiency Enhancement in High Index Nanowires\n  Resonators: Light trapping in sub-wavelength semiconductor nanowires (NWs) offers a\npromising approach to simultaneously reducing material consumption and\nenhancing photovoltaic performance. Nevertheless, the absorption efficiency of\na NW, defined by the ratio of optical absorption cross section to the NW\ndiameter, lingers around 1 in existing NW photonic devices, and the absorption\nenhancement suffers from a narrow spectral width. Here, we show that the\nabsorption efficiency can be significantly improved in NWs with higher\nrefractive indices, by an experimental observation of up to 350% external\nquantum efficiency (EQE) in lead sulfide (PbS) NW resonators, a 3-fold increase\ncompared to Si NWs. Furthermore, broadband absorption enhancement is achieved\nin single tapered NWs, where light of various wavelengths is absorbed at\nsegments with different diameters analogous to a tandem solar cell. Overall,\nthe single NW Schottky junction solar cells benefit from optical resonance,\nnear bandgap open circuit voltage, and long minority carrier diffusion length,\ndemonstrating power conversion efficiency (PCE) comparable to single Si NW\ncoaxial p-n junction cells11, but with much simpler fabrication processes.",
        "positive": "Many-body theory for proton-induced point-defect effects on losses of\n  electron energy and photons in quantum wells: The effects of point defects on the loss of either energies of ballistic\nelectron beams or incident photons are studied by using a many-body theory in a\nmulti-quantum-well system. This includes the defect-induced vertex correction\nto a bare polarization function of electrons within the ladder approximation as\nwell as the intralayer and interlayer screening of defect-electron interactions\nare also taken into account in the random-phase approximation. The numerical\nresults of defect effects on both energy-loss and optical-absorption spectra\nare presented and analyzed for various defect densities, number of quantum\nwells, and wave vectors. The diffusion-reaction equation is employed for\ncalculating distributions of point defects in a layered structure. For\ncompleteness, the production rate for Frenkel-pair defects and their initial\nconcentration are obtained based on atomic-level molecular-dynamics\nsimulations. By combining defect-effect, diffusion-reaction and\nmolecular-dynamics models proposed in this paper with a space-weather forecast\nmodel for the first time, it will be possible to enable specific designing for\nelectronic and optoelectronic quantum devices that will be operated in space\nwith radiation-hardening protection, and therefore, will effectively extend the\nlifetime of these satellite onboard electronic and optoelectronic devices."
    },
    {
        "anchor": "Non-equilibrium electronic structure of interacting single-molecule\n  nanojunctions: vertex corrections and polarization effects for the\n  electron-vibron coupling: We consider the interaction between electrons and molecular vibrations in the\ncontext of electronic transport in nanoscale devices. We present a method based\non non-equilibrium Green's functions to calculate both equilibrium and\nnon-equilibrium electronic properties of a single-molecule junction in the\npresence of electron-vibron interactions. We apply our method to a model system\nconsisting of a single electronic level coupled to a single vibration mode in\nthe molecule, which is in contact with two electron reservoirs. Higher-order\ndiagrams beyond the usual self-consistent Born approximation (SCBA) are\nincluded in the calculations. In this paper we consider the effects of the\ndouble-exchange diagram and the diagram in which the vibron propagator is\nrenormalized by one electron-hole bubble. We study in detail the effects of the\nfirst- and second-order diagrams on the spectral functions for a large set of\nparameters and for different transport regimes (resonant and off-resonant\ncases), both at equilibrium and in the presence of a finite applied bias. We\nalso study the linear response (linear conductance) of the nanojunction for all\nthe different regimes. We find that it is indeed necessary to go beyond the\nSCBA in order to obtain correct results for a wide range of parameters.",
        "positive": "Charge fluctuations in single-electron tunneling oscillations: It has been predicted that in the presence of a sufficiently high-dissipative\nenvironment transport in a small tunnel junction can become extremely regular,\ngiving rise to the phenomenon of single-electron tunneling oscillations. Recent\nprogress in detection of high-frequency current fluctuations and the interest\nin single-electron sources motivate further investigations on the expected\naccuracy of the charge oscillations as a function of the impedance of the\nenvironment. In this paper we study theoretically the charge-fluctuation\nspectrum at finite frequency for the system at hand, and investigate its\nevolution as a function of the external impedance. The evolution and the\ndisappearance of the single-electron oscillations peak is described by\nanalytical and numerical methods."
    },
    {
        "anchor": "Topologically protected defect states in open photonic systems with\n  non-hermitian charge-conjugation and parity-time symmetry: We show that topologically protected defect states can exist in open (leaky\nor lossy) systems even when these systems are topologically trivial in the\nclosed limit. The states appear from within the continuum, thus in absence of a\nband gap, and are generated via exceptional points (a spectral transition that\noccurs in open wave and quantum systems with a generalized time-reversal\nsymmetry), or via a degeneracy induced by charge-conjugation-symmetry (which is\nrelated to the pole transition of Majorana zero modes). We demonstrate these\nfindings for a leaking passive coupled-resonator optical waveguide with\nasymmmetric internal scattering, where the required symmetries (non-hermitian\nversions of time-reversal symmetry, chirality and charge-conjugation) emerge\ndynamically.",
        "positive": "Non-Hermitian Hamiltonian approach to quantum transport in disordered\n  networks with sinks: validity and effectiveness: We investigate the validity of the non-Hermitian Hamiltonian approach in\ndescribing quantum transport in disordered tight-binding networks connected to\nexternal environments, acting as sinks. Usually, non-Hermitian terms are added,\non a phenomenological basis, to such networks to summarize the effects of the\ncoupling to the sinks. Here we consider a paradigmatic model of open quantum\nnetwork for which we derive a non-Hermitian effective model, discussing its\nlimit of validity by a comparison with the analysis of the full Hermitian\nmodel. Specifically, we consider a ring of sites connected to a central\none-dimensional lead. The lead acts as a sink which absorbs the excitation\ninitially present in the ring. The coupling strength to the lead controls the\nopening of the ring system. This model has been widely discussed in literature\nin the context of light-harvesting systems. We analyze the effectiveness of the\nnon-Hermitian description both in absence and in presence of static disorder on\nthe ring. In both cases, the non-Hermitian model is valid when the energy range\ndetermined by the eigenvalues of the ring Hamiltonian is smaller than the\nenergy band in the lead. Under such condition, we show that results about the\ninterplay of opening and disorder, previously obtained within the non-Hermitian\nHamiltonian approach, remain valid when the full Hermitian model in presence of\ndisorder is considered. The results of our analysis can be extended to generic\nnetworks with sinks, leading to the conclusion that the non-Hermitian approach\nis valid when the energy dependence of the coupling to the external\nenvironments is sufficiently smooth in the energy range spanned by the\neigenstates of the network."
    },
    {
        "anchor": "Controlling selection rules for magnon scattering in nanomagnets by\n  spatial symmetry breaking: Nanomagnets are the building blocks of many existing and emergent spintronic\ntechnologies. Magnetization dynamics of nanomagnets is often dominated by\nnonlinear processes, which have been recently shown to have many surprising\nfeatures and far-reaching implications for applications. Here we develop a\ntheoretical framework uncovering the selection rules for multimagnon processes\nand discuss their underlying mechanisms. For its technological relevance, we\nfocus on the degenerate three-magnon process in thin elliptical nanodisks to\nillustrate our findings. We parameterize the selection rules through a set of\nmagnon interaction coefficients which we calculate using micromagnetic\nsimulations. We postulate the selection rules and investigate how they are\naltered by perturbations, that break the symmetry of static magnetization\nconfiguration and spatial spin-wave profiles and that can be realized by\napplying off-symmetry-axis or nonuniform magnetic fields. Our work provides the\nphenomenological understanding into the mechanics of magnon interaction as well\nas the formalism for determining the interaction coefficients from simulations\nand experimental data. Our results serve as a guide to analyze magnon processes\ninherently present in spin-torque devices for boosting their performance or to\nengineer a specific nonlinear response of a nanomagnet used in neuromorphic or\nquantum magnonic application.",
        "positive": "Generation and evolution of spin-, valley- and layer-polarized excited\n  carriers in inversion-symmetric WSe2: Manipulation of spin and valley degrees of freedom is a key step towards\nrealizing novel quantum technologies, for which atomically thin transition\nmetal dichalcogenides (TMDCs) have been established as promising candidates. In\nmonolayer TMDCs, the lack of inversion symmetry gives rise to a spin-valley\ncorrelation of the band structure allowing for valley-selective electronic\nexcitation with circularly polarized light. Here we show that, even in\ncentrosymmetric samples of 2H-WSe2, circularly polarized light can generate\nspin-, valley- and layer-polarized excited states in the conduction band.\nEmploying time- and angle-resolved photoemission spectroscopy (trARPES) with\nspin-selective excitation, the dynamics of valley and layer pseudospins of the\nexcited carriers are investigated. Complementary time-dependent density\nfunctional theory (TDDFT) calculations of the excited state populations reveal\na strong circular dichroism of the spin-, valley- and layer-polarizations and a\npronounced 2D character of the excited states in the K valleys. We observe\nscattering of carriers towards the global minimum of the conduction band on a\nsub-100 femtosecond timescale to states with three-dimensional character\nfacilitating inter-layer charge transfer. Our results establish the optical\ncontrol of coupled spin-, valley- and layer-polarized states in centrosymmetric\nmaterials and suggest the suitability of TMDC multilayer materials for\nvalleytronic and spintronic device concepts."
    },
    {
        "anchor": "Vacancy-Induced Topological Fano Resonance in Kane-Mele Nanoribbons:\n  Design, Control, and Sensing Applications: The concept of topological Fano resonance, characterized by an ultrasharp\nasymmetric line shape, is a promising candidate for robust sensing applications\ndue to its sensitivity to external parameters and immunity to structural\ndisorder. In this study, the vacancy-induced topological Fano resonance in a\nnanoribbon made up of a hexagonal lattice with armchair sides is examined by\nintroducing several on-site vacancies, which are deliberately created at\nregular distances, along a zigzag chain that stretches across the width of the\nribbon. The presence of the on-site vacancies can create localized energy\nstates within the electronic band structure, leading to the formation of an\nimpurity band, which can result in Fano resonance phenomena by forming a\nconductivity channel between the edge modes on both armchair sides of the\nribbon. Consequently, an ultracompact tunable on-chip integrated topological\nFano resonance derived from the graphene-based nanomechanical phononic crystals\nis proposed. The Fano resonance arises from the interference between\ntopologically protected even and odd edge modes at the interface between\ntrivial and nontrivial insulators in a nanoribbon structure governed by the\nKane-Mele model describing the quantum spin Hall effect in hexagonal lattices.\nThe simulation of the topological Fano resonance is performed analytically\nusing the Lippmann-Schwinger scattering formulation. One of the advantages of\nthe present study is that the related calculations are carried out\nanalytically, and in addition to the simplicity and directness, it reproduces\nthe results obtained from the Landauer-B\\\"{u}ttiker formulation very well both\nquantitatively and qualitatively. The findings open up possibilities for the\ndesign of highly sensitive and accurate robust sensors for detecting extremely\ntiny forces, masses, and spatial positions.",
        "positive": "Lasing and Amplification from Two-Dimensional Atom Arrays: We explore the ability of two-dimensional periodic atom arrays to produce\nlight amplification and generate laser emission when gain is introduced through\nexternal optical pumping. Specifically, we predict that lasing can take place\nfor arbitrarily weak atomic scatterers assisted by cooperative interaction\namong atoms in a 2D lattice. We base this conclusion on analytical theory for\nthree-level scatterers, which additionally reveals a rich interplay between\nlattice and atomic resonances. Our results provide a general background to\nunderstand light amplification and lasing in periodic atomic arrays, with\npromising applications in the generation, manipulation, and control of coherent\nphoton states at the nanoscale."
    },
    {
        "anchor": "Optical spectroscopy of molecular junctions: Nonequilibrium Green's\n  functions perspective: We consider optical spectroscopy of molecular junctions from the quantum\ntransport perspective when radiation field is quantized and optical response of\nthe system is simulated as photon flux. Using exact expressions for photon and\nelectronic fluxes derived within the nonequilibrium Green function (NEGF)\nmethodology and utilizing fourth order diagrammatic perturbation theory in\nmolecular coupling to radiation field we perform simulations employing\nrealistic parameters. Results of the simulations are compared to the bare\nperturbation theory (PT) usually employed in studies on nonlinear optical\nspectroscopy to classify optical processes. We show that the bare PT violates\nconservation laws, while flux conserving NEGF formulation mixes optical\nprocesses.",
        "positive": "Electronic Devices Based on Purified Carbon Nanotubes Grown By High\n  Pressure Decomposition of Carbon Monoxide: The excellent properties of transistors, wires, and sensors made from\nsingle-walled carbon nanotubes (SWNTs) make them promising candidates for use\nin advanced nanoelectronic systems. Gas-phase growth procedures such as the\nhigh pressure decomposition of carbon monoxide (HiPCO) method yield large\nquantities of small diameter semiconducting SWNTs, which are ideal for use in\nnanoelectronic circuits. As-grown HiPCO material, however, commonly contains a\nlarge fraction of carbonaceous impurities that degrade properties of SWNT\ndevices. Here we demonstrate a purification, deposition, and fabrication\nprocess that yields devices consisting of metallic and semiconducting nanotubes\nwith electronic characteristics vastly superior to those of circuits made from\nraw HiPCO. Source-drain current measurements on the circuits as a function of\ntemperature and backgate voltage are used to quantify the energy gap of\nsemiconducting nanotubes in a field effect transistor geometry. This work\ndemonstrates significant progress towards the goal of producing complex\nintegrated circuits from bulk-grown SWNT material."
    },
    {
        "anchor": "Strong Superconducting Proximity Effect in Pb-Bi2Te3 Hybrid Structures: Majarona fermions (MFs) were predicted more than seven decades ago but are\nyet to be identified [1]. Recently, much attention has been paid to search for\nMFs in condensed matter systems [2-10]. One of the seaching schemes is to\ncreate MF at the interface between an s-wave superconductor (SC) and a 3D\ntopological insulator (TI) [11-13]. Experimentally, progresses have been\nachieved in the observations of a proximity-effect-induced supercurrent\n[14-16], a perfect Andreev reflection [17] and a conductance peak at the Fermi\nlevel [18]. However, further characterizations are still needed to clarify the\nnature of the SC-TI interface. In this Letter, we report on a strong proximity\neffect in Pb-Bi2Te3 hybrid structures, based on which Josephson junctions and\nsuperconducting quantum interference devices (SQUIDs) can be constructed.\nJosephson devices of this type would provide a test-bed for exploring novel\nphenomena such as MFs in the future.",
        "positive": "Observation and manipulation of a phase separated state in a charge\n  density wave material: The 1T polytype of TaS$_\\textrm{2}$ has been studied extensively as a\nstrongly correlated system. As 1T-TaS$_\\textrm{2}$ is thinned towards the 2D\nlimit, its phase diagram shows significant deviations from that of the bulk\nmaterial. Optoelectronic maps of ultrathin 1T-TaS$_\\textrm{2}$ have indicated\nthe presence of non-equilibrium charge density wave phases within the\nhysteresis region of the nearly commensurate (NC) to commensurate (C)\ntransition. We perform scanning tunneling microscopy on exfoliated ultrathin\nflakes of 1T-TaS$_\\textrm{2}$ within the NC-C hysteresis window, finding\nevidence that the observed non-equilibrium phases consist of intertwined,\nirregularly shaped NC-like and C-like domains. After applying lateral\nelectrical signals to the sample we image changes in the geometric arrangement\nof the different regions. We use a phase separation model to explore the\nrelationship between electronic inhomogeneity present in ultrathin\n1T-TaS$_\\textrm{2}$ and its bulk resistivity. These results demonstrate the\nrole of phase competition morphologies in determining the properties of 2D\nmaterials."
    },
    {
        "anchor": "Quantum Stirring in low dimensional devices: A circulating current can be induced in the Fermi sea by displacing a\nscatterer, or more generally by integrating a quantum pump into a closed\ncircuit. The induced current may have either the same or the opposite sense\nwith respect to the \"pushing\" direction of the pump. We work out explicit\nexpressions for the associated geometric conductance using the Kubo-Dirac\nmonopoles picture, and illuminate the connection with the theory of adiabatic\npassage in multiple path geometry.",
        "positive": "Channel length dependence of the formation of quantum dots in GaN/AlGaN\n  FETs: Quantum dots can be formed in simple GaN/AlGaN field-effect-transistors\n(FETs) by disordered potential induced by impurities and defects. Here, we\ninvestigate the channel length dependence of the formation of quantum dots. We\nobserve decrease of the number of formed quantum dots with decrease of the FET\nchannel length. A few quantum dots are formed in the case with the gate length\nof 0.05~$\\mu $m and we evaluate the dot parameters and the disordered\npotential. We also investigate the effects of a thermal cycle and illumination\nof light, and reveal the change of the disordered potential."
    },
    {
        "anchor": "On the topological surface states of the intrinsic magnetic topological\n  insulator Mn-Bi-Te family: We review recent progress in the electronic structure study of intrinsic\nmagnetic topological insulators (MnBi$_2$Te$_4$)(Bi$_2$Te$_3$)$_n$\n($n=0,1,2,3$) family. Specifically, we focus on the ubiquitously (nearly)\ngapless behavior of the topological surface state Dirac cone observed by\nphotoemission spectroscopy, even though a large Dirac gap is expected because\nof surface ferromagnetic order. The dichotomy between experiment and theory\nconcerning this gap behavior is perhaps the most critical and puzzling question\nin this frontier. We discuss various proposals accounting for the lack of\nmagnetic effect on the topological surface state Dirac cone, which are mainly\ncategorized into two pictures, magnetic reconfiguration, and topological\nsurface state redistribution. Band engineering towards opening a magnetic gap\nof topological surface states provides great opportunities to realize quantized\ntopological transport and axion electrodynamics at higher temperatures.",
        "positive": "Optical tuning and ultrafast dynamics of high-temperature\n  superconducting terahertz metamaterials: Through the integration of semiconductors or complex oxides into metal\nresonators, tunable metamaterials have been achieved by a change of environment\nusing an external stimulus. Metals provide high conductivity to realize a\nstrong resonant response in metamaterials; however, they contribute very little\nto the tunability. The complex conductivity in high-temperature superconducting\nfilms is highly sensitive to external perturbations, which provides new\nopportunities in achieving tunable metamaterials resulting directly from the\nresonant elements. Here we demonstrate ultrafast dynamical tuning of resonance\nin the terahertz (THz) frequency range in YBa_2Cu_3O_7-\\delta (YBCO) split-ring\nresonator arrays excited by near-infrared femtosecond laser pulses. The\nphotoexcitation breaks the superconducting Cooper pairs to create the\nquasiparticle state. This dramatically modifies the imaginary part of the\ncomplex conductivity and consequently the metamaterial resonance in an\nultrafast timescale. We observed resonance switching accompanied with a wide\nrange frequency tuning as a function of photoexcitation fluence, which also\nstrongly depend on the nano-scale thickness of the superconducting films. All\nof our experimental results are well reproduced through calculations using an\nanalytical model, which takes into account the SRR resistance and kinetic\ninductance contributed from the complex conductivity of YBCO films. The\ntheoretical calculations reveal that the increasing SRR resistance upon\nincreasing photoexcitation fluence is responsible for the reduction of\nresonance strength, and both the resistance and kinetic inductance contribute\nto the tuning of resonance frequency."
    },
    {
        "anchor": "Robust operation of a GaAs tunable barrier electron pump: We demonstrate the robust operation of a gallium arsenide tunable-barrier\nsingle-electron pump operating with 1 part-per-million accuracy at a\ntemperature of $1.3$~K and a pumping frequency of $500$~MHz. The accuracy of\ncurrent quantisation is investigated as a function of multiple control\nparameters, and robust plateaus are seen as a function of three control gate\nvoltages and RF drive power. The electron capture is found to be in the\ndecay-cascade, rather than the thermally-broadened regime. The observation of\nrobust plateaus at an elevated temperature which does not require expensive\nrefrigeration is an important step towards validating tunable-barrier pumps as\npractical current standards.",
        "positive": "Optical conductivity of bilayer graphene with and without an asymmetry\n  gap: When a bilayer of graphene is placed in a suitably configured field effect\ndevice, an asymmetry gap can be generated and the carrier concentration made\ndifferent in each layer. This provides a tunable semiconducting gap, and the\nvalence and the conductance band no longer meet at the two Dirac points of the\ngraphene Brillouin zone. We calculate the optical conductivity of such a\nsemiconductor with particular emphasis on the optical spectral weight\nredistribution brought about by changes in gap and chemical potential due to\ncharging. We derive an algebraic formula for arbitrary value of the chemical\npotential for the case of the bilayer conductivity without a gap."
    },
    {
        "anchor": "The importance of chemical potential in the determination of water slip\n  in nanochannels: We investigate the slip properties of water confined in graphite-like\nnano-channels by non-equilibrium molecular dynamics simulations, with the aim\nof identifying and analyze separately the influence of different physical\nquantities on the slip length. In a system under confinement but connected to a\nreservoir of fluid, the chemical potential is the natural control parameter: we\nshow that two nanochannels characterized by the same macroscopic contact angle\n-- but a different microscopic surface potential -- do not exhibit the same\nslip length unless the chemical potential of water in the two channels is\nmatched. Some methodological issues related to the preparation of samples for\nthe comparative analysis in confined geometries are also discussed.",
        "positive": "Effects of Diffusion on Photocurrent Generation in Single-Walled Carbon\n  Nanotube Films: We have studied photocurrent generation in large carbon nanotube (CNT) films\nusing electrodes with different spacings. We observe that the photocurrent\ndepends strongly on the position of illumination, with maximum observed\nresponse occurring upon illumination at the electrode edges. The rate of change\nof the response decays exponentially, with the fastest response occurring for\nsamples with the smallest electrode spacing. We show that the time response is\ndue to charge carrier diffusion in low-mobility CNT films."
    },
    {
        "anchor": "Thermal and quantum fluctuations in chains of ultracold polar molecules: Ultracold polar molecules, in highly anisotropic traps and interacting via a\nrepulsive dipolar potential, may form one-dimensional chains at high densities.\nAccording to classical theory, at low temperatures there exists a critical\nvalue of the density at which a second order phase transition from a linear to\na zigzag chain occurs. We study the effect of thermal and quantum fluctuations\non these self-organized structures using classical and quantum Monte Carlo\nmethods, by means of which we evaluate the pair correlation function and the\nstatic structure factor. Depending on the parameters, these functions exhibit\nproperties typical of a crystalline or of a liquid system. We compare the\nthermal and the quantum results, identifying analogies and differences.\nFinally, we discuss experimental parameter regimes where the effects of quantum\nfluctuations on the linear - zigzag transition can be observed.",
        "positive": "Capillary-Wave Model for the Solidification of Dilute Binary Alloys: Starting from a phase-field description of the isothermal solidification of a\ndilute binary alloy, we establish a model where capillary waves of the\nsolidification front interact with the diffusive concentration field of the\nsolute. The model does not rely on the sharp-interface assumption, and includes\nnon-equilibrium effects, relevant in the rapid-growth regime. In many\napplications it can be evaluated analytically, culminating in the appearance of\nan instability which, interfering with the Mullins-Sekerka instability, is\nsimilar to that, found by Cahn in grain-boundary motion."
    },
    {
        "anchor": "Parity-to-charge conversion in Majorana qubit readout: We study the time-dependent effect of Markovian readout processes on Majorana\nqubits whose parity degrees of freedom are converted into the charge of a\ntunnel-coupled quantum dot. By applying a recently established effective\nLindbladian approximation [1-3], we obtain a completely positive and trace\npreserving Lindblad master equation for the combined dot-qubit dynamics,\ndescribing relaxation and decoherence processes beyond the rotating-wave\napproximation. This approach is applicable to a wide range of weakly coupled\nenvironments representing experimentally relevant readout devices. We study in\ndetail the case of thermal decay in the presence of a generic Ohmic bosonic\nbath, in particular for potential fluctuations in an electromagnetic circuit.\nIn addition, we consider the nonequilibrium measurement environment for a\nparity readout using a quantum point contact capacitively coupled to the dot\ncharge.",
        "positive": "Self-duality triggered dynamical transition: A basic result about the dynamics of spinless quantum systems is that the\nMaryland model exhibits dynamical localization in any dimension. Here we\nimplement mathematical spectral theory and numerical experiments to show that\nthis result does not hold, when the 2-dimensional Maryland model is endowed\nwith spin 1/2 -- hereafter dubbed spin-Maryland (SM) model. Instead, in a\nfamily of SM models, tuning the (effective) Planck constant drives dynamical\nlocalization{delocalization transitions of topological nature. These\ntransitions are triggered by the self-duality, a symmetry generated by some\ntransformation in the parameter -- the inverse Planck constant -- space. This\nprovides significant insights to new dynamical phenomena such as what occur in\nthe spinful quantum kicked rotor."
    },
    {
        "anchor": "Modular Cryogenic Interconnects for Multi-Qubit Devices: We have developed a modular interconnect platform for the control and readout\nof multiple solid-state qubits at cryogenic temperatures. The setup provides 74\nfiltered dc-bias connections, 32 control and readout connections with a\nbandwidth above 5 GHz, and 4 microwave feed lines that allow operation to above\n10 GHz. The incorporation of a radio-frequency (rf) interposer enables the\nplatform to be separated into two printed circuit boards, decoupling the simple\nboard that is bonded to the qubit chip from the multilayer board that\nincorporates expensive connectors and components. This modular approach lifts\nthe burden of duplicating complex interconnect circuits for every prototype\ndevice. We report the performance of this platform at milli-Kelvin\ntemperatures, including signal transmission and crosstalk measurements.",
        "positive": "Realization of a Spin Glass in a two-dimensional van der Waals material: Recent advances in van der Waals (vdW) materials have sparked renewed\ninterest in the impact of dimensionality on magnetic phase transitions. While\nordered magnetic phases have been demonstrated to survive in the\ntwo-dimensional (2D) limit, the quest for a spin-glass with quenched magnetic\ndisorder in lower dimensions has proven elusive. Here we show evidence of a\nspin-glass emerging from randomly distributed Fe atoms in Fe3GeTe2, the first\ntime such a state has been reported in a vdW material. AC magnetic\nsusceptibility displays a strong frequency dependence indicative of slow spin\ndynamics. Additional distinctive phenomena, including ageing, chaos, and memory\neffects, further substantiate the existence of a glassy state. Remarkably, we\nfind that this state persists even in single-unit-cell thick Fe3GeTe2, thereby\nconfirming the existence of a 2D spin-glass. The formation of spin-glass states\nvia intercalation in vdW systems allows for highly tunable spin-glass states\nthat are otherwise difficult to realize."
    },
    {
        "anchor": "Non-Kondo zero bias anomaly in electronic transport through an\n  ultra-small Si quantum dot: We have studied low-temperature single electron transport through ultra-small\nSi quantum dots. We find that at low temperatures Coulomb blockade is partially\nlifted at certain gate voltages. Furthermore, we observed an enhancement of\ndifferential conductance at zero bias. The magnetic field dependence of this\nzero bias anomaly is very different from the one reported in GaAs quantum dots,\ninconsistent with predictions for the Kondo effect.",
        "positive": "Probing barrier transmission in ballistic graphene: We derive the local density of states from itinerant and boundary states\naround transport barriers and edges in graphene and show that the itinerant\nstates lead to mesoscale undulations that could be used to probe their\nscattering properties in equilibrium without the need for lateral transport\nmeasurements. This finding will facilitate vetting of extended structural\ndefects such as grain boundaries or line defects as transport barriers for\nswitchable graphene resonant tunneling transistors. We also show that barriers\ncould exhibit double minima and that the charge density away from highly\nreflective barriers and edges scales as $x^{-2}$."
    },
    {
        "anchor": "Optical signature of cascade transitions between moir\u00e9 interlayer\n  excitons: Cascade transition between energy levels has important applications, such as\nin quantum information protocols and quantum cascade lasers. In two-dimensional\nheterostructure, the moir\\'e superlattice potential can result in multiple\ninterlayer exciton (IX) energy levels. We demonstrate the cascade transitions\nbetween such moir\\'e IXs by performing time- and energy-resolved\nphotoluminescence measurements. We show that the lower-energy moir\\'e IX can be\nexcited to higher-energy ones, facilitating IX population inversion.",
        "positive": "Valley Spin Sum Rule for Dirac Fermions: Topological Argument: We consider a two-dimensional bipartite lattice system. In such a system, the\nBloch band spectrum can have some valley points, around which Dirac fermions\nappear as the low-energy excitations. Each valley point has a valley spin +1 or\n-1. In such a system, there are two topological numbers counting vortices and\nmerons in the Brillouin zone, respectively. These numbers are equivalent, and\nthis fact leads to a sum rule which states that the total sum of the valley\nspins is absent even in a system without time-reversal and parity symmetries.\nWe can see some similarity between the valley spin and chirality in the\nNielsen-Ninomiya no-go theorem in odd-spatial dimensions."
    },
    {
        "anchor": "Inverse-current quantum electro-oscillations in a charge-density wave\n  insulator: Quantum magneto-oscillations have long been a vital subject in condensed\nmatter physics with ubiquitous quantum phenomena and various underlying\nphysical mechanisms. Here, we demonstrate the intrinsic and reproducible\nd.c.-currentdriven quantum electro-oscillations with a periodicity in the\ninverse of current (1/I), in quasi-one-dimensional charge-density-wave (CDW)\ninsulator (TaSe$_4$)$_2$I and TaS$_3$ nanowires. Such oscillations manifest in\nthe nearly infinite Frohlich conductivity region where the CDW depinning occurs\nin a finite electric current, and finally disappear after the oscillation index\nn reaches 1. A systematic investigation on the effect of temperature and\nmagnetic field establishes that the observed electro-oscillations are a\ncoherent quantum phenomenon. A possible mechanism is proposed based on\nzero-phason-assisted resonant tunneling, associated with sliding-driven\ninherent Floquet sidebands. Our results introduce a new member in the quantum\noscillations family, and shed light on plausible routes to explore novel\nphysics and potential applications of coherent density-wave condensates.",
        "positive": "The $\u03c9$-SQUIPT: phase-engineering of Josephson topological\n  materials: Multi-terminal superconducting Josephson junctions based on the proximity\neffect offer the bright opportunity to tailor non trivial quantum states in\nnanoscale weak-links. These structures can realize exotic topologies in\nmultidimensions as, for example, artificial topological superconductors able to\nsupport Majorana bound states, and pave the way to emerging quantum\ntechnologies and future quantum information schemes. Here, we report the first\nrealization of a three-terminal Josephson interferometer based on a proximized\nnanosized weak-link. Our tunneling spectroscopy measurements reveal transitions\nbetween gapped (i.e., insulating) and gapless (i.e., conducting) states, those\nbeing controlled by the phase configuration of the three superconducting leads\nconnected to the junction. We demonstrate the $topological$ nature of these\ntransitions: a gapless state necessarily occurs between two gapped states of\ndifferent topological index, very much like the interface between two\ninsulators of different topology is necessarily conducting. The topological\nnumbers characterizing such gapped states are given by superconducting phase\nwindings over the two loops forming the Josephson interferometer. Since these\ngapped states cannot be transformed to one another continuously withouth\npassing through a gapless condition, these are topologically $protected$. Our\nobservation of the gapless state is pivotal for enabling phase engineering of\nmore sophisticated artificial topological materials realizing Weyl points or\nthe anomalous Josephson effect."
    },
    {
        "anchor": "Nonsingular vortices-skyrmions for odd Landau level fillings in 2d\n  system: Using gradient expansion method the particle density, the energy and the\naction were calculated at the formation of a vortex-skyrmion at high magnetic\nfield. No approximation of single Landau level was used contrary to other\npapers on the subject. Taking into account the nearest Landau levels\nessentially changes the expression for the vortex energy and gives some simple\nphysical interpretation of the main results. The local electron density\ncoincides with the local density of states. It is shown that the formation of a\nvortex skyrmion gives the gain in the thermodynamic energy in the limit of\nalarge magnetic field and a small value of the g-factor. That means a\nspontaneous formation of vortices in this case. The Hopf term in the\nvortex-skyrmion action is calculated and corresponds to the fermionic picture.",
        "positive": "Real Space Renormalization of the Chalker-Coddington Model: We study a number of hierarchical network models related to the\nChalker-Coddington model of quantum percolation. Our aim is to describe the\nphysics of the quantum Hall transition. The hierarchical network models are\nconstructed by combining series and parallel composition of quantum resistors.\nThe localization-delocalization transition occurring in these models is treated\nby real space renormalization techniques. Essentially, the\nlocalization-delocalization transition is due to a competition between two\none-dimensional localization mechanisms."
    },
    {
        "anchor": "Nonlinear Photoluminescence in Atomically Thin Layered WSe2 Arising from\n  Diffusion-Assisted Exciton-Exciton Annihilation: We studied multi-exciton dynamics in monolayer WSe2 using nonlinear\nphotoluminescence (PL) spectroscopy and Monte Carlo simulations. We observed\nstrong nonlinear saturation behavior of exciton PL with increasing excitation\npower density, and long-distance exciton diffusion reaching several\nmicrometers. We demonstrated that the diffusion-assisted exciton-exciton\nannihilation model accounts for the observed nonlinear PL behavior. The\nlong-distance exciton diffusion and subsequent efficient exciton-exciton\nannihilation process determined the unusual multi-exciton dynamics in\natomically thin layered transition metal dichalcogenides.",
        "positive": "Semiclassical description of electronic supershells in simple metal\n  clusters: A semiclassical approach for calculating shell effects, that has been used in\natomic and plasma physics, is applied to describe the electronic supershells in\nmetal clusters. Using the spherical jellium model we give the analytical\nexpression for the oscillating part of the binding energy of electrons as an\nexplicit sum of contributions from supershells with quantum numbers 2n_r+l,\n3n_r+l, 4n_r+l, ... This expression is written in terms of the classical\ncharacteristics of the motion of an electron with the Fermi energy in a\nself-consistent potential. The conditions under which a new supershell appears\nand the relative contribution of this shell are studied as a function of the\ncluster size and form of the potential. Specific calculations are performed for\na square well."
    },
    {
        "anchor": "Non-linear and negative effective diffusivity of optical excitations in\n  moir\u00e9-free heterobilayers: Interlayer exciton diffusion is studied in atomically-reconstructed\nMoSe2/WSe2 heterobilayers with suppressed disorder. Local atomic registry is\nconfirmed by characteristic optical absorption, circularly-polarized\nphotoluminescence, and g-factor measurements. Using transient microscopy we\nobserve propagation properties of interlayer excitons that are independent from\ntrapping at moir\\'e- or disorder-induced local potentials. Confirmed by\ncharacteristic temperature dependence for free particles, linear diffusion\ncoefficients of interlayer excitons at liquid helium temperature and low\nexcitation densities are almost 1000 times higher than in previous\nobservations. We further show that exciton-exciton repulsion and annihilation\ncontribute nearly equally to non-linear propagation by disentangling the two\nprocesses in the experiment and simulations. Finally, we demonstrate effective\nshrinking of the light-emission over time across several 100's of picoseconds\nat the transition from exciton- to the plasma-dominated regimes. Supported by\nmicroscopic calculations for bandgap renormalization to identify Mott\nthreshold, this indicates transient crossing between rapidly expanding,\nshort-lived electron-hole plasma and slower, long-lived exciton populations.",
        "positive": "Specific heat measurement of thin suspended SiN membrane from 8 K to 300\n  K using the 3$\u03c9$-V$\\ddot{o}$lklein method: We present a specific heat measurement technique adapted to thin or very thin\nsuspended membranes from low temperature (8 K) to 300 K. The presented device\nallows the measurement of the heat capacity of a 70 ng silicon nitride membrane\n(50 or 100 nm thick), corresponding to a heat capacity of 1.4x10$^{-10}$ J/K at\n8 K and 5.1x10$^{-8}$ J/K at 300 K. Measurements are performed using the\n3$\\omega$ method coupled to the V$\\ddot{o}$lklein geometry. This configuration\nallows the measurement of both specific heat and thermal conductivity within\nthe same experiment. A transducer (heater/thermometer) is used to create an\noscillation of the heat flux on the membrane; the voltage oscillation appearing\nat the third harmonic which contains the thermal information is measured using\na Wheatstone bridge set-up. The heat capacity measurement is performed by\nmeasuring the variation of the 3$\\omega$ voltage over a wide frequency range\nand by fitting the experimental data using a thermal model adapted to the heat\ntransfer across the membrane. The experimental data are compared to a regular\nDebye model; the specific heat exhibits features commonly seen for glasses at\nlow temperature."
    },
    {
        "anchor": "The Smallest Metallic Nanorods Using Physical Vapor Deposition: We first present a theory of the smallest diameter and then use the theory to\nguide the experimental realization of Cu nanorods of ~20 nm in diameter and Au\nnanorods of ~10 nm in diameter, the smallest well-separated metallic nanorods\never reported using PVD.",
        "positive": "Parallel carbon nanotube quantum dots and their interactions: We present quantum transport measurements of interacting parallel quantum\ndots formed in the strands of a carbon nanotube rope. In this molecular quantum\ndot system, transport is dominated by one quantum dot, while additional\nresonances from parallel side dots appear, which exhibit a weak gate coupling.\nThis differential gating effect provides a tunability of the quantum dot system\nwith only one gate electrode and provides control over the carbon nanotube\nstrand that carries the current. By tuning the system to different states we\nuse quantum transport as a spectroscopic tool to investigate the inter-dot\ncoupling and show a route to distinguish between various side dots. By\ncomparing the experimental data with master equation calculations, we identify\nconditions for the tunneling rates that are required in order to observe\ndifferent manifestations of the inter-dot coupling in the transport spectra."
    },
    {
        "anchor": "Interaction of surface acoustic waves with electronic excitations in\n  graphene: This article reviews the main theoretical and experimental advances regarding\nthe interaction between surface acoustic waves (SAWs) and electronic\nexcitations in graphene. The coupling of the graphene electron gas to the SAW\npiezoelectric field can modify the propagation properties of the SAW, and even\namplify the intensity of SAWs traveling along the graphene layer. Conversely,\nthe periodic electric and strain fields of the SAW can be used to modify the\ngraphene Dirac cone and to couple light into graphene plasmons. Finally, SAWs\ncan generate acousto-electric currents in graphene. These increase linearly\nwith the SAW frequency and power but, in contrast to conventional currents,\nthey depend non-monotonously on the graphene electric conductivity. Most of\nthese functionalities have been reported in graphene transferred to the surface\nof strong piezoelectric insulators. The recent observation of acousto-electric\ncurrents in epitaxial graphene on SiC opens the way to the large-scale\nfabrication of graphene-based acousto-electric devices patterned directly on a\nsemi-insulating wafer.",
        "positive": "Vortices in Atomic Bose-Einstein Condensates: an Introduction: The occurrence of vortices in atomic Bose-Einstein condensates (BEC) enables\na description of their superfluid behaviour. In this article we present a\npedagogical introduction to the vortex physics in trapped atomic BECs. The\nmechanism of the vortex nucleation in an atomic BEC is discussed in detail. We\nalso discuss a recently proposed approach which treats the problem of vortex\nnucleation using a one-particle Schr$\\ddot{o}$dinger equation with non-local\nand chiral boundary conditions."
    },
    {
        "anchor": "Identification of transverse spin currents in noncollinear magnetic\n  structures: We show that the transverse components of spin current in a ferromagnet is\nlinked to an off diagonal spin component of the transmission matrix at\ninterfaces;it has little to do with the mismatch of band structures between\ndissimilar metals. When we take account of this component,not considered in\nprior analyses, we find spin torque comes from a region of at lease 3 nm around\nan interface.",
        "positive": "Density Functional Based Simulations of Proton Permeation of Graphene\n  and Hexagonal Boron Nitride: Using density functional theory, we study proton permeation through graphene\nand hexagonal boron nitride. We consider several factors influencing the\nbarriers for permeation, including structural optimization, the role of the\nsolvent, surface curvature and proton transport through hydrogenated samples.\nFurthermore, we discuss the ground state charge transfer from the membrane to\nthe proton and the strong tendency for bond formation. If the process is\nassumed to be slow we find that none of these effects lead to a satisfactory\nanswer to the observed discrepancies between theory and experiment."
    },
    {
        "anchor": "Scaling approach to tight-binding transport in realistic graphene\n  devices: the case of transverse magnetic focusing: Ultra-clean graphene sheets encapsulated between hexagonal boron nitride\ncrystals host two-dimensional electron systems in which low-temperature\ntransport is solely limited by the sample size. We revisit the theoretical\nproblem of carrying out microscopic calculations of non-local ballistic\ntransport in such micron-scale devices. By employing the Landauer-Buttiker\nscattering theory, we propose a novel scaling approach to tight-binding\nnon-local transport in realistic graphene devices. We test our numerical method\nagainst experimental data on transverse magnetic focusing (TMF), a textbook\nexample of non-local ballistic transport in the presence of a transverse\nmagnetic field. This comparison enables a clear physical interpretation of all\nthe observed features of the TMF signal, including its oscillating sign.",
        "positive": "Electrical transport through single-molecule junctions: from molecular\n  orbitals to conduction channels: We present an atomistic theory of electronic transport through single organic\nmolecules that reproduces the important features of the current-voltage\ncharacteristics observed in recent experiments. We trace these features to\ntheir origin in the electronic structure of the molecules and their local\natomic environment. We demonstrate how conduction channels arise from the\nmolecular orbitals and elucidate which specific properties of the individual\norbitals determine their contribution to the current."
    },
    {
        "anchor": "Polarizability, plasmons, and screening in 1T${^\\prime}$-MoS$_2$ with\n  tilted Dirac bands: In the presence of an external vertical electric field and strain, it is\nevident that 1T${^\\prime}$-MoS$_2$ exhibits tilted Dirac bands which are\nvalley-spin-polarized. Additionally, this material experiences a topological\nphase change between a topological insulator and band insulator for a critical\nvalue of the electric field. Using linear response theory, we calculated the\npolarization function which is in turn employed to obtain the dielectric\nfunction. This latter quantity is subsequently utilized in calculations to\ndetermine the plasmons dispersion relation, their decay rate and impurity\nscreening corresponding to various levels of doping, the critical applied\nvertical electric field strengths and the spin-orbit coupling gap in\n1T${^\\prime}$-MoS$_2$ with tilted Dirac bands.",
        "positive": "Operando Control of Skyrmion Density in a Lorentz Transmission Electron\n  Microscope with Current Pulses: Magnetic skyrmions hold promise for spintronic devices. To explore the\ndynamical properties of skyrmions in devices, a nanoscale method to image spin\ntextures in response to a stimulus is essential. Here, we apply a technique for\noperando electrical current pulsing of chiral magnetic devices in a Lorentz\ntransmission electron microscope. In ferromagnetic multilayers with interfacial\nDzyaloshinskii-Moriya interaction (DMI), we study the creation and annihilation\nof skyrmions localized by point-like pinning sites due to defects. Using a\ncombination of experimental and micromagnetic techniques, we establish a\nthermal contribution for the creation and annihilation of skyrmions in our\nstudy. Our work reveals a mechanism for controlling skyrmion density, which\nenables an examination of skyrmion magnetic field stability as a function of\ndensity. We find that high-density skyrmion states are more stable than\nlow-density states or isolated skyrmions resisting annihilation over a magnetic\nfield range that increases monotonically with density."
    },
    {
        "anchor": "Topological phase transition and quantum spin Hall state in TlBiS$_2$: We have investigated the bulk and surface electronic structures and band\ntopology of TlBiS$_2$ as a function of strain and electric field using\n\\textit{ab-initio} calculations. In its pristine form, TlBiS$_2$ is a normal\ninsulator, which does not support any non-trivial surface states. We show\nhowever that a compressive strain along the (111) direction induces a single\nband inversion with Z$_2$ = (1;000), resulting in a Dirac cone surface state\nwith a large in-plane spin polarization. Our analysis shows that a critical\npoint lies between the normal and topological phases where the dispersion of\nthe 3D bulk Dirac cone at the $\\Gamma$-point becomes nearly linear. The band\ngap in thin films of TlBiS$_2$ can be tuned through an out-of-the-plane\nelectric field to realize a topological phase transition from a trivial\ninsulator to a quantum spin Hall state. An effective $\\mathbf{k \\cdot p}$ model\nHamiltonian is presented to simulate our first-principles results on TlBiS$_2$.",
        "positive": "Observation of magnon-mediated current drag in Pt/yttrium iron\n  garnet/Pt(Ta) trilayers: Pure spin current, a flow of spin angular momentum without flow of any\ncompanying net charge, is generated in two common ways. One makes use of the\nspin Hall effect in normal metals (NM) with strong spin-orbit coupling, such as\nPt or Ta. The other utilizes the collective motion of magnetic moments or spin\nwaves with the quasi-particle excitations called magnons. A popular material\nfor the latter is yttrium iron garnet, a magnetic insulator (MI). Here we\ndemonstrate in NM/MI/NM trilayers that these two types of spin currents are\ninterconvertible across the interfaces, predicated as the magnon-mediated\ncurrent drag phenomenon. The transmitted signal scales linearly with the\ndriving current without a threshold and follows the power-law with n ranging\nfrom 1.5 to 2.5. Our results indicate that the NM/MI/NM trilayer structure can\nserve as a scalable pure spin current valve device which is an essential\ningredient in spintronics."
    },
    {
        "anchor": "Boundary conditions for transition-metal dichalcogenide monolayers in\n  the continuum model: We derive the boundary conditions for MoS$_2$ and similar transition-metal\ndichalcogenide honeycomb (2H polytype) monolayers with the same type of\n$\\mathbf{k}\\!\\cdot\\!\\mathbf{p}$ Hamiltonian within the continuum model around\nthe K points. In an effective 2-band description, the electron-hole symmetry\nbreaking quadratic terms are also taken into account. We model the effect of\nthe edges with a linear edge constraint method that has been applied previously\nto graphene. Focusing mainly on zigzag edges, we find that different\nreconstruction geometries with different edge-atoms can generally be described\nwith one scalar parameter varying between 0 and $2\\pi$. We analyze the edge\nstates and their dispersion relation in MoS$_2$ in particular, and we find good\nagreement with the results of previous density functional theory calculations\nfor various edge types.",
        "positive": "Non-Fermi-Liquid Behavior of Compressible States of Electrons on the\n  Lowest Landau Level: Experiments show that at even denominator fractions (EDFs) ($\\nu=1/2, 3/4,\n3/2$,...) the two-dimensional electron gas in a strong magnetic field becomes\ncompressible, has no energy gap, and demonstrates the presence of an ostensible\nFermi surface. Since this phenomenon results from a minimization of the\ninteraction, rather than the kinetic energy, the EDF states might well exhibit\ndeviations from a conventional Fermi liquid. We show that impurity scattering\nat EDFs and its interference with electron-electron and electron-phonon\ninteractions provide examples of intrinsically non-Fermi-liquid transport."
    },
    {
        "anchor": "Experimental Evidence for Crossed Andreev Reflection: We report on electronic transport properties of mesoscopic\nsuperconductor-ferromagnet spin-valve structures. Two ferromagnetic iron leads\nform planar tunnel contacts to a superconducting aluminum wire, where the\ndistance of the two contacts is of the order of the coherence length of the\naluminum. We observe a negative non-local resistance which can be explained by\ncrossed Andreev reflection, a process where an electron incident from one of\nthe leads gets reflected as a hole into the other, thereby creating a pair of\nspatially separated, entangled particles.",
        "positive": "Nonvolatile Memory Cells Based on MoS2/Graphene Heterostructures: Memory cells are an important building block of digital electronics. We\ncombine here the unique electronic properties of semiconducting monolayer MoS2\nwith the high conductivity of graphene to build a 2D heterostructure capable of\ninformation storage. MoS2 acts as a channel in an intimate contact with\ngraphene electrodes in a field-effect transistor geometry. Our prototypical\nall-2D transistor is further integrated with a multilayer graphene charge\ntrapping layer into a device that can be operated as a nonvolatile memory cell.\nBecause of its band gap and 2D nature, monolayer MoS2 is highly sensitive to\nthe presence of charges in the charge trapping layer, resulting in a factor of\n10000 difference between memory program and erase states. The two-dimensional\nnature of both the contact and the channel can be harnessed for the fabrication\nof flexible nanoelectronic devices with large-scale integration."
    },
    {
        "anchor": "Charge quantization and detector resolution: Charge quantization, or the absence thereof, is a central theme in quantum\ncircuit theory, with dramatic consequences for the predicted circuit dynamics.\nVery recently, the question of whether or not charge should actually be\ndescribed as quantized has enjoyed renewed widespread interest, with however\nseemingly contradictory propositions. Here, we intend to reconcile these\ndifferent approaches, by arguing that ultimately, charge quantization is not an\nintrinsic system property, but instead depends on the spatial resolution of the\ncharge detector. We show that the latter can be directly probed by unique\ngeometric signatures in the correlations of the supercurrent. We illustrate\nthese findings at the example Josephson junction arrays in the superinductor\nregime, where the transported charge appears to be continuous. Finally, we\ncomment on potential consequences of charge quantization beyond superconducting\ncircuits.",
        "positive": "Dynamics of artificial spin ice: continuous honeycomb network: We model the dynamics of magnetization in an artificial analog of spin ice\nspecializing to the case of a honeycomb network of connected magnetic\nnanowires. The inherently dissipative dynamics is mediated by the emission,\npropagation and absorption of domain walls in the links of the lattice. These\ndomain walls carry two natural units of magnetic charge, whereas sites of the\nlattice contain a unit magnetic charge. Magnetostatic Coulomb forces between\nthese charges play a major role in the physics of the system, as does quenched\ndisorder caused by imperfections of the lattice. We identify and describe\ndifferent regimes of magnetization reversal in an applied magnetic field\ndetermined by the orientation of the applied field with respect to the initial\nmagnetization. One of the regimes is characterized by magnetic avalanches with\na 1/n distribution of lengths."
    },
    {
        "anchor": "Electron Localization in the Quantum-Hall Regime: The theory of the insulating state discriminates between insulators and\nmetals by means of a localization tensor, which is finite in insulators and\ndivergent in metals. In absence of time-reversal symmetry, this same tensor\nacquires an offdiagonal imaginary part, proportional to the dc transverse\nconductivity, leading to quantization of the latter in two-dimensional systems.\nI provide evidence that electron localization--in the above sense--is the\ncommon cause for both vanishing of the dc longitudinal conductivity and\nquantization of the transverse one in quantum-Hall fluids.",
        "positive": "Macroscopic quantum-mechanical scattering: In certain conditions a macroscopic quantum-mechanical scattering may occur,\nwhich may lead to a coherent cross-section on a macroscopic scale in a\nmonocrystal. The conditions are satisfied by neutrinos, but not satisfied by\nother projectiles, with a higher cross-section. This may explain Weber-type\nexperiments of neutrino detection by a perfect, stiff sapphire monocrystal. The\noccurrence of coherence domains for quantum-mechanical scattering and classical\ndiffraction is analyzed, and the force exerted upon a macroscopic target is\nestimated. It is concluded that neutrinos exhibit a distinctive feature in this\nrespect, due precisely to their very small cross-section."
    },
    {
        "anchor": "Spectroscopy of electron flows with single- and two-particle emitters: To analyze the state of injected carrier streams of different electron\nsources, we propose to use correlation measurements at a quantum point contact\nwith the different sources connected via chiral edge states to the two inputs.\nIn particular we consider the case of an on-demand single-electron emitter\ncorrelated with the carriers incident from a biased normal reservoir, a contact\nsubject to an alternating voltage and a stochastic single electron emitter. The\ncorrelation can be viewed as a spectroscopic tool to compare the states of\ninjected particles of different sources. If at the quantum point contact the\namplitude profiles of electrons overlap, the noise correlation is suppressed.\nIn the absence of an overlap the noise is roughly the sum of the noise powers\ndue to the electron streams in each input. We show that the electron state\nemitted from a (dc or ac) biased metallic contact is different from a\nLorentzian amplitude electron state emitted by the single electron emitter (a\nquantum capacitor driven with slow harmonic potential), since with these inputs\nthe noise correlation is not suppressed. In contrast, if quantized voltage\npulses are applied to a metallic contact instead of a dc (ac) bias then the\nnoise can be suppressed. We find a noise suppression for multi-electron pulses\nand for the case of stochastic electron emitters for which the appearance of an\nelectron at the quantum point contact is probabilistic.",
        "positive": "Study of magneto-transport properties and quantum oscillations in PbSe\n  single crystals: PbSe is a low-gap semiconductor with excellent infrared photo-detection\nproperties. Here we report our high magnetic field and low temperature\nelectrical properties measurement performed on a moderately doped PbSe single\ncrystals with p-type bulk carrier density of around $1\\times10^{18}$ cm$^{-3}$.\nLongitudinal resistance (R$_{xx}$) and Hall resistance (R$_{xy}$) were\nsimultaneously measured between 0 T--18 T at several temperatures between 0.8\nK--25 K. These transport measurements start showing oscillatory behavior around\nand above 6 T of magnetic field. The quantum oscillation frequency is ~15 T,\ngiving an estimate for the carrier density of each L pocket in the BZ\nparticipating in these oscillations. The effective mass of the free carriers is\nestimated from the temperature dependence of oscillation amplitudes.\nMeasurements as the magnetic fields is rotated reveal the magneto-transport\nproperties of a 3D-like fermi surface. Free carrier scattering rate from the\ntransport data has been estimated which also gave an estimation of Dingle\ntemperature in PbSe. Room temperature optical measurements has been conducted\nand other optical properties has been estimated. The Drude-Lorentz model fit\nhas been performed which show a low frequency phonon mode around 45 cm$^{-1}$\nand bandgap of around 0.2 eV along with other interband electronic transitions.\nSome of the optical and transport results has been compared against other\nmembers of class IV-VI chalcogenides."
    },
    {
        "anchor": "Symmetry-induced even/odd parity in charge and heat pumping: It is shown that the presence of discrete symmetries in Floquet systems\nconnected to metallic reservoirs imprints a definite parity on the charge and\nheat pumping as a function of the reservoir's chemical potential, $\\mu$. In\nparticular, when particle-hole symmetry (PHS) holds, the pumping of charge\n(heat) is an odd (even) function of $\\mu$. Whereas, if only the product of PHS\nand parity symmetry is present, pumping of charge (heat) is even (odd) in\n$\\mu$. Our results also extend to the presence of other unitary symmetries and\nprovide a simple criterion for reversing (or maintaining) the direction of the\nflow. We illustrate our findings using two variants of the Su-Schrieffer-Heeger\nmodel under a time-periodic perturbation.",
        "positive": "Anatomy of open-boundary bulk in multiband non-Hermitian systems: Although the non-Bloch band theory is a milestone in elaborating bulk energy\nbands of non-Hermitian systems under the open-boundary condition (OBC), vital\nissues related to multivalued functions of non-Hermitian energy bands remain\nunsolved. In this paper, we anatomize the bulk properties of one-dimensional\nmultiband non-Hermitian systems under OBC. We put forward the energy-band\nbranches (EBBs) to settle the multivalued functions of non-Hermitian energy\nbands, which become gapped or gapless corresponding to disconnected or\nconnected EBBs in the complex energy plane, where the branch points and branch\ncuts play a crucial role. We clarify the precise significance of the\nnon-Hermitian skin effect, which illustrates the asymptotic behavior of EBB\neigenstates (bulk eigenstates) in the deep bulk and compensates previous\nnon-Bloch band theory. We also obtain a general expression of open-boundary\nGreen's functions based on such EBBs and generalized Brillouin zones, useful\nfor studies on non-Hermitian dynamical evolution."
    },
    {
        "anchor": "Surface plasmon scattering by shallow and deep surface defects: Surface plasmon scattering by 1D indentations and protrusions is examined,\nmainly in the optical regime. The width of the defects is fixed, while its\nheight is varied. Both individual and arrays of defects are considered.\nProtrusions mainly reflect the incident plasmons in the optical range.\nIndentations mainly radiate the incident plasmon out of plane. An indentation\nproduces maximum reflections and out-of-plane radiation at the same wavelength,\nwhen its interaction with the incident surface plasmon is resonant.\nProtrusions, in general, exhibit maximum reflection and radiation at different\nwavelengths. Shallow arrays of either defects produce a photonic band-gap,\nwhose spectral width can be broadened by increasing the defects height or\ndepth. At wavelengths inside the bandgap ridge arrays reflect SPPs better than\ngroove arrays, while groove arrays radiate SPPs better than ridge arrays.",
        "positive": "Plasmon modes in double-layer biased bilayer graphene: We investigate zero-temperature plasmon modes in a double-layer bilayer\ngraphene structure under a perpendicular electrostatic bias. The numerical\nresults demonstrate that there exist two collective modes which are undamped in\nthe long wavelength limit. The finite potential bias decreases remarkably the\nplasmon energy in a wide range of wave-vector and makes plasmon branches become\nLandau damped at a higher wave-vector as compared to unbiased case. We find\nthat the dependence of plasmon dispersions on the system parameters such as the\ninter-layer separation and carrier density is similar in two cases with and\nwithout electrostatic bias."
    },
    {
        "anchor": "Mesoscopic fluctuations of Coulomb drag between quasi-ballistic 1D-wires: Quasiballistic 1D quantum wires are known to have a conductance of the order\nof 2e^2/h, with small sample-to-sample fluctuations. We present a study of the\ntransconductance G_12 of two Coulomb-coupled quasiballistic wires, i.e., we\nconsider the Coulomb drag geometry. We show that the fluctuations in G_12\ndiffer dramatically from those of the diagonal conductance G_ii: the\nfluctuations are large, and can even exceed the mean value, thus implying a\npossible reversal of the induced drag current. We report extensive numerical\nsimulations elucidating the fluctuations, both for correlated and uncorrelated\ndisorder. We also present analytic arguments, which fully account for the\ntrends observed numerically.",
        "positive": "Tailoring spin-orbit torque in diluted magnetic semiconductors: We study the spin orbit torque arising from an intrinsic linear Dresselhaus\nspin-orbit coupling in a single layer III-V diluted magnetic semiconductor. We\ninvestigate the transport properties and spin torque using the linear response\ntheory and we report here : (1) a strong correlation exists between the angular\ndependence of the torque and the anisotropy of the Fermi surface; (2) the spin\norbit torque depends nonlinearly on the exchange coupling. Our findings suggest\nthe possibility to tailor the spin orbit torque magnitude and angular\ndependence by structural design."
    },
    {
        "anchor": "Connecting electron and phonon spectroscopy data to consistently\n  determine quasiparticle-phonon coupling on the surface of topological\n  insulators: Photoemission and phonon spectroscopies have yielded widely varying estimates\nof the electron-phonon coupling constant \\lambda\\ on the surfaces of\ntopological insulators, even for a particular material and technique. We\nconnect the results of these experiments by determining the Dirac fermion\nquasiparticle spectral function using information from measured spectra of a\nstrongly-interacting, low-lying optical surface phonon band. The manifest\nspectral features resulting from the coupling are found to vary on energy\nscales < 1 meV, and are distinct from those traditionally observed in the case\nof acoustic phonons in metals. We explore different means of determining\n\\lambda\\ from the electron perspective and identify definitions that yield\nvalues consistent with phonon spectroscopy.",
        "positive": "Femtosecond photo-switching of interface polaritons in black phosphorus\n  heterostructures: The possibility of hybridizing collective electronic motion with mid-infrared\n(mid-IR) light to form surface polaritons has made van der Waals layered\nmaterials a versatile platform for extreme light confinement and tailored\nnanophotonics. Graphene and its heterostructures have attracted particular\nattention because the absence of an energy gap allows for plasmon polaritons to\nbe continuously tuned. Here, we introduce black phosphorus (BP) as a promising\nnew material in surface polaritonics that features key advantages for ultrafast\nswitching. Unlike graphene, BP is a van der Waals bonded semiconductor, which\nenables high-contrast interband excitation of electron-hole pairs by ultrashort\nnear-infrared (near-IR) pulses. We design a SiO$_2$/BP/SiO$_2$ heterostructure\nin which the surface phonon modes of the SiO$_2$ layers hybridize with surface\nplasmon modes in BP that can be activated by photo-induced interband\nexcitation. Within the Reststrahlen band of SiO$_2$, the hybrid interface\npolariton assumes surface-phonon-like properties, with a well-defined frequency\nand momentum and excellent coherence. During the lifetime of the photogenerated\nelectron-hole plasma, coherent polariton waves can be launched by a broadband\nmid-IR pulse coupled to the tip of a scattering-type scanning near-field\noptical microscopy (s-SNOM) setup. The scattered radiation allows us to trace\nthe new hybrid mode in time, energy, and space. We find that the surface mode\ncan be activated within ~50 fs and disappears within 5 ps, as the electron-hole\npairs in BP recombine. The excellent switching contrast and switching speed,\nthe coherence properties, and the constant wavelength of this transient mode\nmake it a promising candidate for ultrafast nanophotonic devices."
    },
    {
        "anchor": "Majorana states in inhomogeneous spin ladders: We propose an inhomogeneous open spin ladder, related to the Kitaev honeycomb\nmodel, which can be tuned between topological and nontopological phases. In\nextension of Lieb's theorem, we show numerically that the ground state of the\nspin ladder is either vortex free or vortex full. We study the robustness of\nMajorana end states (MES) which emerge at the boundary between sections in\ndifferent topological phases and show that while the MES in the homogeneous\nladder are destroyed by single-body perturbations, in the presence of\ninhomogeneities at least two-body perturbations are required to destabilize\nMES. Furthermore, we prove that x, y, or z inhomogeneous magnetic fields are\nnot able to destroy the topological degeneracy. Finally, we present a\ntrijunction setup where MES can be braided. A network of such spin ladders\nprovides thus a promising platform for realization and manipulation of MES.",
        "positive": "Evidence for pairing states of composite fermions in double-layer\n  graphene: Pairing interaction between fermionic particles leads to composite Bosons\nthat condense at low temperature. Such condensate gives rise to long range\norder and phase coherence in superconductivity, superfluidity, and other exotic\nstates of matter in the quantum limit. In graphene double-layers separated by\nan ultra-thin insulator, strong interlayer Coulomb interaction introduces\nelectron-hole pairing across the two layers, resulting in a unique superfluid\nphase of interlayer excitons. In this work, we report a series of emergent\nfractional quantum Hall ground states in a graphene double-layer structure,\nwhich is compared to an expanded composite fermion model with two-component\ncorrelation. The ground state hierarchy from bulk conductance measurement and\nHall resistance plateau from Coulomb drag measurement provide strong\nexperimental evidence for a sequence of effective integer quantum Hall effect\nstates for the novel two-component composite fermions (CFs), where CFs fill\ninteger number of effective LLs (Lambda-level). Most remarkably, a sequence of\nincompressible states with interlayer correlation are observed at half-filled\nLambda-levels, which represents a new type of order involving pairing states of\nCFs that is unique to graphene double-layer structure and beyond the\nconventional CF model."
    },
    {
        "anchor": "First-principles vs. semi-empirical modeling of global and local\n  electronic transport properties of graphene nanopore-based sensors for DNA\n  sequencing: Using first-principles quantum transport simulations, based on the\nnonequilibrium Green function formalism combined with density functional theory\n(NEGF+DFT), we examine changes in the total and local electronic currents\nwithin the plane of graphene nanoribbon with zigzag edges (ZGNR) hosting a\nnanopore which are induced by inserting a DNA nucleobase into the pore. We find\na sizable change of the zero-bias conductance of two-terminal ZGNR + nanopore\ndevice after the nucleobase is placed into the most probable position\n(according to molecular dynamics trajectories) inside the nanopore of a small\ndiameter \\mbox{$D=1.2$ nm}. Although such effect decreases as the nanopore size\nis increased to \\mbox{$D=1.7$ nm}, the contrast between currents in ZGNR +\nnanopore and ZGNR + nanopore + nucleobase systems can be enhanced by applying a\nsmall bias voltage $V_b \\lesssim 0.1$ V. This is explained microscopically as\nbeing due to DNA nucleobase-induced modification of spatial profile of local\ncurrent density around the edges of ZGNR. We repeat the same analysis using\nNEGF combined with self-consistent charge density functional tight-binding\n(NEGF+SCC-DFTB) or self-consistent extended H\\\"{u}ckel (NEGF+SC-EH)\nsemi-empirical methodologies. The large discrepancy we find between the results\nobtained from NEGF+DFT vs. those obtained from NEGF+SCC-DFTB or NEGF+SC-EH\napproaches could be of great importance when selecting proper computational\nalgorithms for {\\em in silico} design of optimal nanoelectronic sensors for\nrapid DNA sequencing.",
        "positive": "Mesoscopic phase statistics of diffuse ultrasound in dynamic matter: Temporal fluctuations in the phase of waves transmitted through a dynamic,\nstrongly scattering, mesoscopic sample are investigated using ultrasonic waves,\nand compared with theoretical predictions based on circular Gaussian\nstatistics. The fundamental role of phase in Diffusing Acoustic Wave\nSpectroscopy is revealed, and phase statistics are also shown to provide a\nsensitive and accurate way to probe scatterer motions at both short and long\ntime scales."
    },
    {
        "anchor": "Optimising motion-induced spin transfer: In this paper, the spin transfer between two ferromagnetic insulators is\nstudied. There is a narrow gap between the ferromagnetic insulators so that\nthey are weakly interacting with each other. One of the ferromagnetic\ninsulators is moving at a constant speed while the other is at rest; hence, the\nsystem is out of equilibrium. In the presence of the shearing motion, the\ninteraction amplitude is periodically modulated at the Doppler frequency. A\nunitary transformation allows us to regard the periodic modulation of the\ninteraction amplitude as an effective potential, which drives the spin\ntransfer. The amount of the spin current is controlled by the spectral overlap\nand the carrier population difference between the two ferromagnetic media. If\nthe spectra of the two ferromagnets are moderately broadened, the overlap in\nthe spectral domain increases, enlarging the spin current. However, too much\nbroadening spoils the spectral overlap and, hence, the spin current. This\nimplies that there is an optimal condition for maximising the spin transfer.",
        "positive": "Broken-Symmetry Quantum Hall States in Twisted Bilayer Graphene: Twisted bilayer graphene offers a unique bilayer two-dimensional-electron\nsystem where the layer separation is only in sub-nanometer scale. Unlike\nBernal-stacked bilayer, the layer degree of freedom is disentangled from spin\nand valley, providing eight-fold degeneracy in the low energy states. We have\ninvestigated broken-symmetry quantum Hall (QH) states and their transitions due\nto the interplay of the relative strength of valley, spin and layer\npolarizations in twisted bilayer graphene. The energy gaps of the\nbroken-symmetry QH states show an electron-hole asymmetric behaviour, and their\ndependence on the induced displacement field are opposite between even and odd\nfilling factor states. These results strongly suggest that the QH states with\nbroken valley and spin symmetries for individual layer become hybridized via\ninterlayer tunnelling, and the hierarchy of the QH states is sensitive to both\nmagnetic field and displacement field due to charge imbalance between layers."
    },
    {
        "anchor": "Topological invariants to characterize universality of boundary charge\n  in one-dimensionalinsulators beyond symmetry constraints: In the absence of any symmetry constraints we address universal properties of\nthe boundary charge $Q_B$ for a wide class of nearest-neighbor tight-binding\nmodels in one dimension with one orbital per site but generic modulations of\non-site potentials and hoppings. We provide a precise formulation of the\nbulk-boundary correspondence relating the boundary charge of a single band\nuniquely to the Zak phase evaluated in a particular gauge. We reveal the\ntopological nature of $Q_B$ by proving the quantization of a topological index\n$eI=\\Delta Q_B - \\bar{\\rho}$, where $\\Delta Q_B$ is the change of $Q_B$ when\nshifting the lattice by one site towards a boundary and $\\bar{\\rho}$ is the\naverage charge per site. For a single band we find this index to be given by\nthe winding number of the fundamental phase difference of the Bloch wave\nfunction between the two lattice sites defining the boundary of a half-infinite\nsystem. For a given chemical potential we establish a central topological\nconstraint $I\\in\\{-1,0\\}$ related only to charge conservation of particles and\nholes. Our results are shown to be stable against disorder and we propose\ngeneralizations to multi-channel and interacting systems.",
        "positive": "AC transport and full-counting statistics of molecular junctions in the\n  weak electron-vibration coupling regime: The coupling of the charge carriers passing through a molecule bridging two\nbulky conductors with local vibrational modes of the molecule, gives rise to\ndistinct features in the electronic transport properties on one hand, and to\nnonequilibrium features in the vibrations' properties, e.g., their population,\non the other. Here we explore theoretically a generic model for a molecular\njunction biased by an arbitrary dc voltage in the weak-coupling regime. We\nanalyze the signature of the electron-vibration interaction on the\nfull-counting statistics of the current fluctuations (i.e., the cumulant\ngenerating-function of the current correlations), we give a detailed account of\nthe response to an ac field exerted on the junction (on top of the dc bias\nvoltage), we study the nonequilibrium distribution of the vibrational modes and\nthe fluctuations they cause in the displacement of the molecule center of mass.\nThe calculations use the technique of nonequilibrium Green's functions, and\ntreat the electron-vibration coupling in perturbation theory, within the\nrandom-phase approximation when required."
    },
    {
        "anchor": "Lasing in dark and bright modes of a finite-sized plasmonic lattice: Lasing at the nanometre scale promises strong light-matter interactions and\nultrafast operation. Plasmonic resonances supported by metallic nanoparticles\nhave extremely small mode volumes and high field enhancements, making them an\nideal platform for studying nanoscale lasing. At visible frequencies, however,\nthe applicability of plasmon resonances is limited due to strong ohmic and\nradiative losses. Intriguingly, plasmonic nanoparticle arrays support\nnon-radiative dark modes that offer longer life-times but are inaccessible to\nfar-field radiation. Here, we show lasing both in dark and bright modes of an\narray of silver nanoparticles combined with optically pumped dye molecules.\nLinewidths of 0.2 nanometers at visible wavelengths and room temperature are\nobserved. Access to the dark modes is provided by a coherent out-coupling\nmechanism based on the finite size of the array. The results open a route to\nutilize all modes of plasmonic lattices, also the high-Q ones, for studies of\nstrong light-matter interactions, condensation and photon fluids.",
        "positive": "Quantum Dualities and Quantum Anomalous Hall Phases with Arbitrary Large\n  Chern Numbers: Quantum duality is a far reaching concept in contemporary theoretical\nphysics. In the present paper, we reveal the quantum dualities in quantum\nanomalous Hall (QAH) phases through concrete two bands Hamiltonian models. Our\nmodels can realize QAH phases with arbitrary large Chern numbers. In real\nmaterials these models may be realized by stacked $n$ layer systems of $c_1=1$\nQAH insulators. The topological phase transitions that can change the Chern\nnumbers are studied. And we investigate the gapless edge modes of our models in\ndetails, and find a new mechanism for the bulk boundary correspondence."
    },
    {
        "anchor": "Negative differential conductivity and population inversion in the\n  double-dot system connected to three terminals: We examine transport and microwave properties of two coupled quantum dots\ntaken in parallel connection to the common left lead and connected to separate\nleads at their right side. In addition, the area between the left lead and the\ndouble-dot structure is threaded by Aharonov-Bohm magnetic flux. We determine\nthe energies and populations of double-dot levels on the microscopic basis\ntaking into account the interdot Coulomb interaction and show that at large\nlead-to-lead bias the population inversion can be achieved. For the case of\nstrong Coulomb repulsion, this inversion leads to level crossing accompanied by\nthe region of negative differential conductivity in the current-voltage\ncharacteristics, whereas for weaker Coulomb repulsion, the resonant microwave\nabsorption becomes negative at high lead-to-lead voltage.",
        "positive": "Direct observation of quantum confinement of massless Dirac fermions in\n  a topological insulator: Since the discovery of topological insulators (TIs)1,2, the peculiar nature\nof their chiral surface states has been experimentally demonstrated both in\nbulk and in film materials with open boundaries3,4. Closed boundary on a TI\nsurface may intrigue more interesting phenomena such as quantum confinement of\nmassless Dirac fermions (DFs), which is analogous to the quantum corral (QC)\nfor massive free electrons on a metal surface5-10. To date, it keeps a highly\nstringent challenge to realize a true Dirac QC due to the unusual transmitting\npower of a massless fermion. Through heteroepitaxially growing a Bi bilayer on\nthe Bi2Te3 surface with appropriate coverage, here we demonstrate the\nrealization of a true Dirac QC. Specifically, spectacular maps of quantum\ninterference in equilateral triangle-shaped QCs surrounded by Bi bilayers are\ndirectly visualized by using a low-temperature scanning tunneling microscope.\nThe present success is ascribed to a perfect orientation matching between the\nQC boundary and the stationary-phase scattering of massless DFs. In addition,\nthe quasiparticle lifetime of the confined DFs is also systematically measured\nand analyzed."
    },
    {
        "anchor": "Next nearest neighbour coupling with spinor polariton condensates: We report on experimental observation of next-nearest-neighbour coupling\nbetween ballistically expanding spinor exciton-polariton condensates in a\nplanar semiconductor microcavity. All-optical control over the coupling\nstrength between neighbouring condensates is demonstrated through\ndistance-periodic pseudospin screening of their ballistic particle outflow due\nto the inherent splitting of the planar cavity transverse-electric (TE) and\ntransverse-magnetic (TM) modes. By screening the nearest-neighbour coupling we\novercome the conventional spatial coupling hierarchy between condensates. This\noffers a promising route towards creating unconventional non-planar many-body\nHamiltonians using networks of ballistically expanding spinor exciton-polariton\ncondensates.",
        "positive": "Magnetic Photocurrents in Multifold Weyl Fermions: We examine the magneto-optical response of chiral multifold fermions.\nSpecifically, we show that they are ideal candidates for observing the Helical\nMagnetic Effect (HME) previously predicted for simple Weyl fermions. Unlike\nWeyl fermions, the HME is present in multifold fermions even in the simplest\ncase where the low-energy dispersion is linear and spherically symmetric. In\nthis ideal case, we derive an analytical expression for the HME and find it is\nproportional to the circular photogalvanic effect; for realistic parameters and\naccounting for the geometry of the setup, the HME photocurrent could be roughly\nthe same order of magnitude as the circular photogalvanic effect observed in\nmultifold fermions. Additional non-linear and symmetry-breaking terms will ruin\nthe quantization but not hurt the observation of the HME."
    },
    {
        "anchor": "Quantum Scattering and Transport in Classically Chaotic Cavities: An\n  Overview of Past and New Results: We develop a statistical theory that describes quantum-mechanical scattering\nof a particle by a cavity when the geometry is such that the classical dynamics\nis chaotic. This picture is relevant to a variety of physical systems, ranging\nfrom atomic nuclei to mesoscopic systems and microwave cavities; the main\napplication to be discussed in this contribution is to electronic transport\nthrough mesoscopic ballistic structures or quantum dots. The theory describes\nthe regime in which there are two distinct time scales, associated with a\nprompt and an equilibrated response, and is cast in terms of the matrix of\nscattering amplitudes S. We construct the ensemble of S matrices using a\nmaximum-entropy approach which incorporates the requirements of flux\nconservation, causality and ergodicity, and the system-specific average of S\nwhich quantifies the effect of prompt processes. The resulting ensemble, known\nas Poisson's kernel, is meant to describe those situations in which any other\ninformation is irrelevant. The results of this formulation have been compared\nwith the numerical solution of the Schroedinger equation for cavities in which\nthe assumptions of the theory hold. The model has a remarkable predictive\npower: it describes statistical properties of the quantum conductance of\nquantum dots, like its average, its fluctuations, and its full distribution in\nseveral cases. We also discuss situations that have been found recently, in\nwhich the notion of stationarity and ergodicity is not fulfilled, and yet\nPoisson's kernel gives a good description of the data. At the present moment we\nare unable to give an explanation of this fact.",
        "positive": "Wave-packet dynamics at the mobility edge in two- and three-dimensional\n  systems: We study the time evolution of wave packets at the mobility edge of\ndisordered non-interacting electrons in two and three spatial dimensions. The\nresults of numerical calculations are found to agree with the predictions of\nscaling theory. In particular, we find that the $k$-th moment of the\nprobability density $<r^k >(t)$ scales like $t^{k/d}$ in $d$ dimensions. The\nreturn probability $P(r=0,t)$ scales like $t^{-D_2/d}$, with the generalized\ndimension of the participation ratio $D_2$. For long times and short distances\nthe probability density of the wave packet shows power law scaling\n$P(r,t)\\propto t^{-D_2/d}r^{D_2-d}$. The numerical calculations were performed\non network models defined by a unitary time evolution operator providing an\nefficient model for the study of the wave packet dynamics."
    },
    {
        "anchor": "First Principle Noncollinear Transport Calculation and Interfacial\n  Spin-flipping of Cu/Co Multilayers: In this paper the first principle noncollinear transport calculation for\nCu/Co(111) including interfacial spin-flipping was performed. We modeled\nspin-flipping at the interface by assuming a noncollinear magnetic structure\nwith random magnetization orientation which satisfied Gaussian distribution\nalong average magnetization direction. The relationship between spin-dependent\nconductance including interfacial spin-flipping and random magnetization\norientation distribution width was obtained. For certain distribution width,\nour defined spin-flipping ratio coincides with the range of experimental\nspin-flipping probability $P=1-e^{-\\delta}$, where $\\delta=0.25\\pm0.1$. The\nmagnetoresistance in Co/Cu/Co spin valve system including interfacial\nspin-flipping has also been calculated.",
        "positive": "Pseudospin and Quantum Computation in Semiconductor Nanostructures: We review the theoretical aspects of pseudospin quantum computation using\nvertically coupled quantum dots in the quantum Hall regime. We discuss the\nrobustness and addressability of these collective, charge-based qubits. The low\nenergy Hilbert space of a coupled set of qubits yields an effective quantum\nIsing model tunable through external gates. An experimental prediction of an\neven-odd effect in the Coulomb blockade spectra of the coupled quantum dot\nsystem probes the parameter regime necessary for realization of these qubits."
    },
    {
        "anchor": "Electron quantum optics as quantum signal processing: The recent developments of electron quantum optics in quantum Hall edge\nchannels have given us new ways to probe the behavior of electrons in quantum\nconductors. It has brought new quantities called electronic coherences under\nthe spotlight. In this paper, we explore the relations between electron quantum\noptics and signal processing through a global review of the various methods for\naccessing single- and two-electron coherences in electron quantum optics. We\ninterpret electron quantum optics interference experiments as analog signal\nprocessing converting quantum signals into experimentally observable quantities\nsuch as current averages and correlations.\n  This point of view also gives us a procedure to obtain quantum information\nquantities from electron quantum optics coherences. We illustrate these ideas\nby discussing two mode entanglement in electron quantum optics. We also sketch\nhow signal processing ideas may open new perspectives for representing\nelectronic coherences in quantum conductors and understand the properties of\nthe underlying many-body electronic state.",
        "positive": "Sequential multi-photon strategy for semiconductor-based terahertz\n  detectors: A semiconductor-based terahertz-detector strategy, exploiting a\nbound-to-bound-to-continuum architecture, is presented and investigated. In\nparticular, a ladder of equidistant energy levels is employed, whose step is\ntuned to the desired detection frequency and allows for sequential multi-photon\nabsorption. Our theoretical analysis demonstrates that the proposed\nmulti-subband scheme could represent a promising alternative to conventional\nquantum-well infrared photodetectors in the terahertz spectral region."
    },
    {
        "anchor": "Localized basis sets for unbound electrons in nanoelectronics: It is shown how unbound electron wave functions can be expanded in a suitably\nchosen localized basis sets for any desired range of energies. In particular,\nwe focus on the use of gaussian basis sets, commonly used in first-principles\ncodes. The possible usefulness of these basis sets in a first-principles\ndescription of field emission or scanning tunneling microscopy at large bias is\nillustrated by studying a simpler related phenomenon: The lifetime of an\nelectron in a H atom subjected to a strong electric field.",
        "positive": "Graphene-Enhanced Single Ion Detectors for Deterministic Near-Surface\n  Dopant Implantation in Diamond: Colour centre ensembles in diamond have been the subject of intensive\ninvestigation for many applications including single photon sources for quantum\ncommunication, quantum computation with optical inputs and outputs, and\nmagnetic field sensing down to the nanoscale. Some of these applications are\nrealised with a single centre or randomly distributed ensembles in chips, but\nthe most demanding application for a large-scale quantum computer will require\nordered arrays. By configuring an electronic-grade diamond substrate with a\nbiased surface graphene electrode connected to charge-sensitive electronics, it\nis possible to demonstrate deterministic single ion implantation for ions\nstopping between 30 and 130~nm deep from a typical stochastic ion source. An\nimplantation event is signalled by a charge pulse induced by the drift of\nelectron-hole pairs from the ion implantation. The ion implantation site is\nlocalised with an AFM nanostencil or a focused ion beam. This allows the\nconstruction of ordered arrays of single atoms with associated colour centres\nthat paves the way for the fabrication of deterministic colour center networks\nin a monolithic device."
    },
    {
        "anchor": "Plunging in the Dirac sea using graphene quantum dots: The dynamics of low energy charge carriers in a graphene quantum dot\nsubjected to a time-dependent local field is investigated numerically. In\nparticular, we study a configuration where a Coulomb electric field is provided\nby an ion traversing the graphene sample. A Galerkin-like numerical scheme is\nintroduced to solve the massless Dirac equation describing charge carriers\nsubjected to space- and time-dependent electromagnetic potentials and is used\nto evaluate the field induced interband transitions. It is demonstrated that as\nthe ion goes through graphene, electron-hole pairs are generated dynamically\nvia the adiabatic pair creation mechanism around avoided crossings, similar to\nelectron-positron pair generation in low energy heavy ion collisions.",
        "positive": "Magnetic higher-order nodal lines: Nodal lines, as one-dimensional band degeneracies in momentum space, usually\nfeature a linear energy splitting. Here, we propose the concept of magnetic\nhigher-order nodal lines, which are nodal lines with higher-order energy\nsplitting and realized in magnetic systems with broken time reversal symmetry.\nWe provide sufficient symmetry conditions for stabilizing magnetic quadratic\nand cubic nodal lines, based on which concrete lattice models are constructed\nto demonstrate their existence. Unlike its counterpart in nonmagnetic systems,\nthe magnetic quadratic nodal line can exist as the only band degeneracy at the\nFermi level. We show that these nodal lines can be accompanied by torus surface\nstates, which form a surface band that span over the whole surface Brillouin\nzone. Under symmetry breaking, these magnetic nodal lines can be transformed\ninto a variety of interesting topological states, such as three-dimensional\nquantum anomalous Hall insulator, multiple linear nodal lines, and magnetic\ntriple-Weyl semimetal. The three-dimensional quantum anomalous Hall insulator\nfeatures a Hall conductivity $\\sigma_{xy}$ quantized in unit of $e^2/(hd)$\nwhere $d$ is the lattice constant normal to the $x$-$y$ plane. Our work reveals\npreviously unknown topological states, and offers guidance to search for them\nin realistic material systems."
    },
    {
        "anchor": "Singlet-doublet transitions of a quantum dot Josephson junction detected\n  in a transmon circuit: We realize a hybrid superconductor-semiconductor transmon device in which the\nJosephson effect is controlled by a gate-defined quantum dot in an InAs/Al\nnanowire. Microwave spectroscopy of the transmon's transition spectrum allows\nus to probe the ground state parity of the quantum dot as a function of gate\nvoltages, external magnetic flux, and magnetic field applied parallel to the\nnanowire. The measured parity phase diagram is in agreement with that predicted\nby a single-impurity Anderson model with superconducting leads. Through\ncontinuous time monitoring of the circuit we furthermore resolve the\nquasiparticle dynamics of the quantum dot Josephson junction across the phase\nboundaries. Our results can facilitate the realization of semiconductor-based\n$0-\\pi$ qubits and Andreev qubits.",
        "positive": "Mobility versus quality in 2D semiconductor structures: We consider theoretically effects of random charged impurity disorder on the\n{\\it quality} of high-mobility two dimensional (2D) semiconductor structures,\nexplicitly demonstrating that the sample mobility is not necessarily a reliable\nor universal indicator of the sample quality in high-mobility modulation-doped\n2D GaAs structures because, depending on the specific system property of\ninterest, mobility and quality may be controlled by different aspects of the\nunderlying disorder distribution, particularly since these systems are\ndominated by long-range Coulomb disorder from both near and far random quenched\ncharged impurities. We show that in the presence of both channel and remote\ncharged impurity scattering, which is a generic situation in modulation-doped\nhigh-mobility 2D carrier systems, it is quite possible for higher (lower)\nmobility structures to have lower (higher) quality as measured by the\ndisorder-induced single-particle level broadening. In particular, we establish\nthat there is no reason to expect a unique relationship between mobility and\nquality in 2D semiconductor structures as both are independent functionals of\nthe disorder distribution, and are therefore, in principle, independent of each\nother. Using a simple, but reasonably realistic, ``2-impurity'' minimal model\nof the disorder distribution, we provide concrete examples of situations where\nhigher (lower) mobilities correspond to lower (higher) sample qualities. We\ndiscuss experimental implications of our theoretical results and comment on\npossible strategies for future improvement of 2D sample quality."
    },
    {
        "anchor": "Negative Viscosity and Eddy Flow of Imbalanced Electron-Hole Liquid in\n  Graphene: We present a hydrodynamic theory for electron-hole magnetotransport in\ngraphene incorporating carrier-population imbalance, energy, and momentum\nrelaxation processes. We focus on the electric response and find that the\ncarrier and energy imbalance relaxation processes strongly modify the shear\nviscosity, so that an effective viscosity can be negative in the vicinity of\ncharge neutrality. We predict an emergent eddy flow pattern of swirling\ncurrents and explore its manifestation in nonlocal resistivity oscillations in\na strip of graphene driven by a source current.",
        "positive": "Spectrum of $\u03c0$ Electrons in Graphene as an Alternant Macromolecule\n  and Its Specific Features in Quantum Conductance: An exact description of $\\pi$ electrons based on the tight-binding model of\ngraphene as an alternant, plane macromolecule is presented. The model molecule\ncan contain an arbitrary number of benzene rings and has armchair- and\nzigzag-shaped edges. This suggests an instructive alternative to the most\ncommonly used approach, where the reference is made to the honeycomb lattice\nperiodic in its A and B sublattices. Several advantages of the macromolecule\nmodel are demonstrated. The newly derived analytical relations detail our\nunderstanding of $\\pi$ electron nature in achiral graphene ribbons and carbon\ntubes and classify these structures as quantum wires."
    },
    {
        "anchor": "Stability of the maximum density droplet in quantum dots at high\n  magnetic fields: We have measured electron transport through a vertical quantum dot containing\na tunable number of electrons between 0 and 40. Over some region in magnetic\nfield the electrons are spin polarized and occupy successive angular momentum\nstates, i.e. the maximum density droplet (MDD) state. The stability region\nwhere the MDD state is the ground state, decreases for increasing electron\nnumber. The instability of the MDD is accompanied by a redistribution of charge\nwhich increases the area of the electron droplet.",
        "positive": "Superconductivity from spin fluctuations and long-range interactions in\n  magic-angle twisted bilayer graphene: Magic-angle twisted bilayer graphene (MATBG) has been extensively explored\nboth theoretically and experimentally as a suitable platform for a rich and\ntunable phase diagram that includes ferromagnetism, charge order, broken\nsymmetries, and unconventional superconductivity. In this work, we investigate\nthe intricate interplay between long-range electron-electron interactions, spin\nfluctuations, and superconductivity in MATBG. By employing a low-energy model\nfor MATBG that captures the correct shape of the flat bands, we explore the\neffects of short- and long-range interactions on spin fluctuations and their\nimpact on the superconducting (SC) pairing vertex in the Random Phase\nApproximation (RPA). We find that the SC state is notably influenced by the\nstrength of long-range Coulomb interactions. Interestingly, our RPA\ncalculations indicate that there is a regime where the system can traverse from\na magnetic phase to the SC phase by \\emph{increasing} the relative strength of\nlong-range interactions compared to the on-site ones. These findings underscore\nthe relevance of electron-electron interactions in shaping the intriguing\nproperties of MATBG and offer a pathway for designing and controlling its SC\nphase."
    },
    {
        "anchor": "Observation of Planar Hall Effect in Topological Insulator --\n  Bi$_2$Te$_3$: Planar Hall effect (PHE) in topological insulators (TIs) is discussed as an\neffect that stems mostly from conduction due to topologically protected surface\nstates. Although surfaces states play a critical role and are of utmost\nimportance in TIs, our present study reflects the need for considering the bulk\nconduction in understanding PHE in TIs. Here, we demonstrate an enhancement in\nPHE amplitude by three times by doubling the thickness of Bi$_2$Te$_3$ film on\nSi (111). The PHE amplitude reaches $\\approx$~6 n$\\Omega$m in 30 quintuple\nlayer (QL) device as compared to $\\approx$~2 n$\\Omega$m in 14 QL. We find that\nthe PHE amplitude increases with temperature in the 30 QL Bi$_2$Te$_3$ films\ngrown on Si (111) and Al$_2$O$_3$ (0001). Our experiments indicate that the\ncontribution of bulk states to PHE in TIs could be significant.",
        "positive": "Electrically tunable dipolar interactions between layer-hybridized\n  excitons: Transition-metal dichalcogenide bilayers exhibit a rich exciton landscape\nincluding layer-hybridized excitons, i.e. excitons which are of partly intra-\nand interlayer nature. In this work, we study hybrid exciton-exciton\ninteractions in naturally stacked WSe$_2$ homobilayers. In these materials, the\nexciton landscape is electrically tunable such that the low-energy states can\nbe rendered more or less interlayer-like depending on the strength of the\nexternal electric field. Based on a microscopic and material-specific\nmany-particle theory, we reveal two intriguing interaction regimes: a\nlow-dipole regime at small electric fields and a high-dipole regime at larger\nfields, involving interactions between hybrid excitons with a substantially\ndifferent intra- and interlayer composition in the two regimes. While the\nlow-dipole regime is characterized by weak inter-excitonic interactions between\nintralayer-like excitons, the high-dipole regime involves mostly\ninterlayer-like excitons which display a strong dipole-dipole repulsion and\ngive rise to large spectral blue-shifts and a highly anomalous diffusion.\nOverall, our microscopic study sheds light on the remarkable electrical\ntunability of hybrid exciton-exciton interactions in atomically thin\nsemiconductors and can guide future experimental studies in this growing field\nof research."
    },
    {
        "anchor": "Self-Organized Platinum Nanoparticles on Freestanding Graphene: Freestanding graphene membranes were successfully functionalized with\nplatinum nanoparticles (Pt NPs). High-resolution transmission electron\nmicroscopy revealed a homogeneous distribution of single-crystal Pt NPs that\ntend to exhibit a preferred orientation. Unexpectedly, the NPs were also found\nto be partially exposed to the vacuum with the top Pt surface raised above the\ngraphene substrate, as deduced from atomic-scale scanning tunneling microscopy\nimages and detailed molecular dynamics simulations. Local strain accumulation\nduring the growth process is thought to be the origin of the NP\nself-organization. These findings are expected to shape future approaches in\ndeveloping Pt NP catalysts for fuel cells as well as NP-functionalized graphene\nbased high-performance electronics.",
        "positive": "Low Temperature Transport in Undoped Mesoscopic Structures: Using high quality undoped GaAs/AlGaAs heterostructures with optically\npatterned insulation between two layers of gates, it is possible to investigate\nvery low density mesoscopic regions where the number of impurities is well\nquantified. Signature appearances of the scattering length scale arise in\nconfined two dimensional regions, where the zero-bias anomaly (ZBA) is also\nobserved. These results explicitly outline the molecular beam epitaxy growth\nparameters necessary to obtain ultra low density large two dimensional regions\nas well as clean reproducible mesoscopic devices."
    },
    {
        "anchor": "Finite difference method for the arbitrary potential in two dimensions:\n  application to double/triple quantum dots: A finite difference method (FDM) applicable to a two dimensional (2D) quantum\ndot was developed as a non-conventional approach to the theoretical\nunderstandings of quantum devices. This method can be applied to a realistic\npotential with an arbitrary shape. Using this method, the Hamiltonian in a\ntri-diagonal matrix could be obtained from any 2D potential, and the\nHamiltonian could be diagonalized numerically for the eigenvalues. The\nlegitimacy of this method was first checked by comparing the results with a\nfinite round well with the analytic solutions. Two truncated harmonic wells\nwere examined as a realistic model potential for lateral double quantum dots\n(DQDs) and for triple quantum dots (TQDs). The successful applications of the\n2D FDM were observed with the entanglements in the DQDs. The level-splitting\nand anticrossing behaviors of the DQDs could be obtained by varying the\ndistance between the dots and by introducing asymmetry in the well-depths. The\n2D FDM results for linear/triangular TQDs were compared with the tight binding\napproximations.",
        "positive": "Direct observation of strong t-e orbital hybridization and the effects\n  of f orbitals: Recent research has revealed that the Cr family perovskite ReCrO$_3$ exhibits\nintriguing magnetic coupling interactions within Cr pairs, which may not follow\nthe Goodenough-Kanamori (GK) rules due to the t-e hybridization between\nCr$^\\mathrm{III}$ ions. We investigate the complex magnetism involving both t-e\nhybridization and Re-$f$ orbitals in the molecular analogue of perovskite\n[$\\mathrm{Ce_2^{III}Ce^{IV}Cr_8^{III}O_8(O_2CPh)_{18}(HO_2CPh)}$]\n($\\mathrm{Ce_3Cr_8}$) using first-principles method. Our results have shown\nthat distinct from the bulk ReCrO$_3$, the superexchange via Cr-$d$ and O-$p$\norbitals can exhibit a unexpected dominate ferromagnetic (FM) Cr-O-Cr\nsuperexchange interaction in $\\mathrm{Ce_3Cr_8}$ due to the strong t-e\nhybridization originated from the distorted molecular structure. The great\nsensitivity of the t-e hybridization with respect to the molecular structure,\ne.g., the angle of Cr-O-Cr, can lead to a ground state transition from\nferromagnetic to antiferromagnetic state with the changes in the angle of\nCr-O-Cr. The Ce-$f$ orbitals near the Fermi level can reduce this sensitivity\nthrough interacting with the Cr-$d$ orbitals via the virtual charge transfer\nprocess. Our results are strongly supported by a modified superexchange model\nbased on the t-e hybridization theory. These findings complete the theory of\nsuperexchange magnetism involving the t-e hybridization and $f$ orbitals, and\nin the meanwhile introduce a new avenue for fine-tuning the magnetic\ncharacteristics via Tm-d/Re-f interactions at nanoscale."
    },
    {
        "anchor": "Nielsen-Ninomiya Theorem with Bulk Topology: Duality in Floquet and\n  Non-Hermitian Systems: The Nielsen-Ninomiya theorem is a fundamental theorem on the realization of\nchiral fermions in static lattice systems in high-energy and condensed matter\nphysics. Here we extend the theorem in dynamical systems, which include the\noriginal Nielsen-Ninomiya theorem in the static limit. In contrast to the\noriginal theorem, which is a no-go theorem for bulk chiral fermions, the new\ntheorem permits them due to bulk topology intrinsic to dynamical systems. The\ntheorem is based on duality enabling a unified treatment of periodically driven\nsystems and non-Hermitian ones. We also present the extended theorem for\nnon-chiral gapless fermions protected by symmetry. Finally, as an application\nof our theorem and duality, we predict a new type of chiral magnetic effect --\nthe non-Hermitian chiral magnetic skin effect.",
        "positive": "Gate-Defined One-Dimensional Channel and Broken Symmetry States in\n  MoS$_2$ van der Waals Heterostructures: We have realized encapsulated trilayer MoS$_2$ devices with gated graphene\ncontacts. In the bulk, we observe an electron mobility as high as\n7000~cm$^{2}$/(V s) at a density of 3 $\\times$ 10$^{12}$~cm$^{-2}$ at a\ntemperature of 1.9~K. Shubnikov--de Haas oscillations start at magnetic fields\nas low as 0.9~T. The observed 3-fold Landau level degeneracy can be understood\nbased on the valley Zeeman effect. Negatively biased split gate electrodes\nallow us to form a channel that can be completely pinched off for sufficiently\nlarge gate voltages. The measured conductance displays plateau-like features."
    },
    {
        "anchor": "Theory of the dipole-exchange spin wave spectrum in ferromagnetic films\n  with in-plane magnetization revisited: We present a refinement of the widely accepted spin-wave spectrum that\nKalinikos and Slavin computed for magnetic films with an in-plane magnetization\n(1986). The spin wave spectrum that follows from the diagonal approximation in\nthis theory becomes inaccurate for relatively thick films, as has already been\nnoted by Kreisel et al. (2009). Rather than solving an integrodifferential\nequation which follows from the magnetostatic Green's function, as done by\nKalinikos and Slavin, we impose the exchange and magnetostatic boundary\nconditions on bulk spin-wave solutions. This boundary problem has an accurate\nanalytical solution which is quantitatively different from the commonly used\ndiagonal theory for magnetic films.",
        "positive": "THz Superradiance from a GaAs: ErAs Quantum Dot Array at Room\n  Temperature: We report experimental evidence that an ErAs quantum-dot array in a GaAs\nmatrix under 1550 nm pulsed excitation produces cooperative spontaneous\nemission-Dicke superradiance-in the terahertz frequency region at room\ntemperature."
    },
    {
        "anchor": "Non-linear coupling between the two oscillation modes of a dc-SQUID: We make a detailed theoretical description of the two-dimensional nature of a\ndc-SQUID, analyzing the coupling between its two orthogonal phase oscillation\nmodes. While it has been shown that the mode defined as \"longitudinal\" can be\ninitialized, manipulated and measured, so as to encode a quantum bit of\ninformation, the mode defined as \"transverse\" is usually repelled at high\nfrequency and does not interfere in the dynamics. We show that, using typical\nparameters of existing devices, the transverse mode energy can be made of the\norder of the longitudinal one. In this regime, we can observe a strong coupling\nbetween these modes, described by an Hamiltonian providing a wide range of\ninteresting effects, such as conditional quantum operations and entanglement.\nThis coupling also creates an atomic-like structure for the combined two mode\nstates, with a V-like scheme.",
        "positive": "Long-Range Interaction between Charge and Spin Qubits in Quantum Dots: We analyze and give estimates for the long-distance coupling via floating\nmetallic gates between different types of spin qubits in quantum dots made of\ndifferent commonly used materials. In particular, we consider the hybrid, the\nsinglet-triplet, and the spin-$1/2$ qubits, and the pairwise coupling between\neach type of these qubits with another hybrid qubit in GaAs, InAs, Si, and\n$\\mathrm{Si_{0.9}Ge_{0.1}}$. We show that hybrid qubits can be capacitively\ncoupled strongly enough to implement two-qubit gates, as long as the distance\nof the dots from the metallic gates is small enough. Thus, hybrid qubits are\ngood candidates for scalable implementations of quantum computing in\nsemiconducting nanostructures."
    },
    {
        "anchor": "Shape fluctuations and optical transition of He$_{2}^{*}$ excimer\n  tracers in superfluid $^4$He: Metastable He$_{2}^{*}$ excimer molecules have been utilized as tracer\nparticles of the normal component in superfluid $^4$He (He II) which can be\nimaged via laser-induced fluorescence. These excimer molecules form tiny\nbubbles in He II and can bind to quantized vortices at sufficiently low\ntemperatures, thereby allowing for direct visualization of vortex dynamics in\nan inviscid superfluid. However, the\n$a^{3}\\Sigma^+_{u}$${\\rightarrow}$$c^{3}\\Sigma^+_{g}$ optical absorption line,\nwhich is responsible for the fluorescence imaging of the He$_{2}^{*}$\nmolecules, is controlled by fluctuations on the bubble shape, and its exact\nline profile is not known at low temperatures. In this paper, we present a\nbubble model for evaluating the surface fluctuation eigenmodes of the excimers\nin He II. The line profile of the\n$a^{3}\\Sigma^+_{u}{\\rightarrow}c^{3}\\Sigma^+_{g}$ transition is calculated at\ndifferent temperatures by considering both the zero-point and thermal\nfluctuations on the bubble shape. We show that, as the temperature drops from\n2~K to 20 mK, the peak absorption strength is enhanced by a factor of about\nfive, accompanying a blueshift of the peak location by about 2 nm. A\ndouble-peak line profile due to the rotational levels of the molecular core can\nbe resolved. This bubble model also allows us to evaluate the stiffness of the\nHe$_{2}^{*}$ bubbles and hence their diffusion constant in He II due to\nscattering off thermal phonons. Our results will aid the design of future\nexperiments on imaging quantized vortices in He II using He$_{2}^{*}$ tracers.",
        "positive": "Fractional Quantum Hall Layer As A Magical Electromagnetic Medium: At a surface between electromagnetic media the Maxwell equations are\nconsistent with either the usual boundary conditions, or exactly one\nalternative: continuity of E(perpendicular), H(perpendicular), D(parallel),\nB(parallel). These alternative, classically inexplicable conditions applied to\nthe top and bottom surfaces of an FQH layer capture exactly its unique\nlow-frequency properties."
    },
    {
        "anchor": "Nonreciprocal Emergence of Hybridized Magnons in magnetic thin Films: We investigate the transfer and control of nonreciprocity through magnons\nthemselves in permalloy thin films deposited on surface oxide silicon\nsubstrate. Evidences of nonreciprocal emergence of hybridized dipole exchange\nmagnons (spin waves) at two permalloy surfaces are provided by studying magnon\ntransmission and asymmetry, via Brillouin light scattering measurements. The\ndipole dominated spin wave and exchange dominated spin wave are found to be\nlocalized near the top and bottom surfaces, respectively, and traveling along\nopposite directions. The nonreciprocity and the localization are intertwined\nand ca n be tuned by an in plane magnetic field. The effects are well explained\nby the magnetostatic theory and can be quantitatively reproduced by the\nmicromagnetic simulations. Our findings provide a simple and flexible approach\nto nonreciprocal all magnon logi c devices with highly compatible with silicon\nbased integrated circuit technology.",
        "positive": "An Exchange-Coupled Donor Molecule in Silicon: Donors in silicon, conceptually described as hydrogen atom analogues in a\nsemiconductor environment, have become a key ingredient of many\n\"More-than-Moore\" proposals such as quantum information processing [1-5] and\nsingle-dopant electronics [6, 7]. The level of maturity this field has reached\nhas enabled the fabrication and demonstration of transistors that base their\nfunctionality on a single impurity atom [8, 9] allowing the predicted\nsingle-donor energy spectrum to be checked by an electrical transport\nmeasurement. Generalizing the concept, a donor pair may behave as a hydrogen\nmolecule analogue. However, the molecular quantum mechanical solution only\ntakes us so far and a detailed understanding of the electronic structure of\nthese molecular systems is a challenge to be overcome. Here we present a\ncombined experimental-theoretical demonstration of the energy spectrum of a\nstrongly interacting donor pair in the channel of a silicon nanotransistor and\nshow the first observation of measurable two-donor exchange coupling. Moreover,\nthe analysis of the three charge states of the pair shows evidence of a\nsimultaneous enhancement of the binding and charging energies with respect to\nthe single donor spectrum. The measured data are accurately matched by results\nobtained in an effective mass theory incorporating the Bloch states\nmultiplicity in Si, a central cell corrected donor potential and a full\nconfiguration interaction treatment of the 2-electron spectrum. Our data\ndescribe the basic 2-qubit entanglement element in Kane's quantum processing\nscheme [1], namely exchange coupling, implemented here in the range of\nmolecular hybridization."
    },
    {
        "anchor": "Identification of exciton complexes in a charge-tuneable Janus WSeS\n  monolayer: Janus transition-metal dichalcogenide monolayers are fully artificial\nmaterials, where one plane of chalcogen atoms is replaced by chalcogen atoms of\na different type. Theory predicts an in-built out-of-plane electric field,\ngiving rise to long-lived, dipolar excitons, while preserving direct-bandgap\noptical transitions in a uniform potential landscape. Previous Janus studies\nhad broad photoluminescence (>15 meV) spectra obfuscating their excitonic\norigin. Here, we identify the neutral, and negatively charged inter- and\nintravalley exciton transitions in Janus WSeS monolayer with $\\sim 6$ meV\noptical linewidth. We combine a recently developed synthesis technique, with\nthe integration of Janus monolayers into vertical heterostructures, allowing\ndoping control. Further, magneto-optic measurements indicate that monolayer\nWSeS has a direct bandgap at the K points. This work provides the foundation\nfor applications such as nanoscale sensing, which relies on resolving excitonic\nenergy shifts, and photo-voltaic energy harvesting, which requires efficient\ncreation of long-lived excitons and integration into vertical heterostructures.",
        "positive": "Metallic phase of the quantum Hall effect in four-dimensional space: We study the phase diagram of the quantum Hall effect in four-dimensional\n(4D) space. Unlike in 2D, in 4D there exists a metallic as well as an\ninsulating phase, depending on the disorder strength. The critical exponent\n$\\nu\\approx 1.2$ of the diverging localization length at the quantum Hall\ninsulator-to-metal transition differs from the semiclassical value $\\nu=1$ of\n4D Anderson transitions in the presence of time-reversal symmetry. Our\nnumerical analysis is based on a mapping of the 4D Hamiltonian onto a 1D\ndynamical system, providing a route towards the experimental realization of the\n4D quantum Hall effect."
    },
    {
        "anchor": "Spin-Orbit Torque in a Single Ferromagnetic Layer with Large Spin-Orbit\n  Coupling: Spin-orbit torque in heavy metal/ferromagnet heterostructures with broken\nspatial inversion symmetry provides an efficient mechanism for manipulating\nmagnetization using a charge current. Here, we report the presence of a spin\ntorque in a single ferromagnetic layer in both asymmetric MgO/Fe0.8Mn0.2 and\nsymmetric MgO/Fe0.8Mn0.2/MgO structures, which manifests itself in the form of\nan effective field transverse to the charge current. The current to effective\nfield conversion efficiency, which is characterized using both the nonlinear\nmagnetoresistance and second-order planar Hall effect methods, is comparable to\nthe efficiency in typical heavy metal/ferromagnet bilayers. We argue that the\ntorque is caused by spin rotation in the vicinity of the surface via impurity\nscattering in the presence of a strong spin-orbit coupling. Instead of\ncancelling off with each other, the torques from the top and bottom surfaces\nsimply add up, leading to a fairly large net torque, which is readily observed\nexperimentally.",
        "positive": "Electromigration of bivalent functional groups on graphene: Chemical functionalization of graphene holds promise for various applications\nranging from nanoelectronics to catalysis, drug delivery, and nano-assembly. In\nmany of these applications it is critical to assess the rates of\nelectromigration - directed motion of adsorbates along the surface of\ncurrent-carrying graphene due to the electron wind force. In this paper, we\ndevelop an accurate analytical theory of electromigration of bivalent\nfunctional groups (epoxide, amine) on graphene. Specifically, we carefully\nanalyze various factors contributing to the electron wind force, such as\nlattice effects and strong scattering beyond Born approximation, and derive a\nsimple analytical expression for this force. Further, we perform accurate\nelectronic structure theory calculations to parameterize the obtained\nanalytical expression. The obtained results can be generalized to different\nfunctional groups and adsorbates, e.g., alkali atoms on graphene."
    },
    {
        "anchor": "FDTD subcell graphene model beyond the thin-film approximation: A subcell technique for calculation of optical properties of graphene with\nthe finite-difference time-domain (FDTD) method is presented. The technique\ntakes into account the surface conductivity of graphene which allows the\ncorrect calculation of its dispersive response for arbitrarily polarized\nincident waves interacting with the graphene.The developed technique is\nverified for a planar graphene sheet configuration against the exact analytical\nsolution. Based on the same test case scenario, we also show that the subcell\ntechnique demonstrates a superior accuracy and numerical efficiency with\nrespect to the widely used thin-film FDTD approach for modeling graphene. We\nfurther apply our technique to the simulations of a graphene metamaterial\ncontaining periodically spaced graphene strips (graphene strip-grating) and\ndemonstrate good agreement with the available theoretical results.",
        "positive": "Light emission from the layered metal 2H-TaSe$_2$ and its potential\n  applications: Conventional metals, in general, do not exhibit strong photoluminescence.\n2H-TaSe$_2$ is a layered transition metal dichalcogenide that possesses\nmetallic property with charge density wave characteristics. Here we show that\n2H-TaSe$_2$ exhibits a surprisingly strong optical absorption and\nphotoluminescence resulting from inter-band transitions. We use this perfect\ncombination of electrical and optical properties in several optoelectronic\napplications. We show a seven-fold enhancement in the photoluminescence\nintensity of otherwise weakly luminescent multi-layer MoS$_2$ through\nnon-radiative resonant energy transfer from TaSe$_2$ transition dipoles. Using\na combination of scanning photocurrent and time-resolved photoluminescence\nmeasurements, we also show that the hot electrons generated by light absorption\nin TaSe$_2$ have a rather long lifetime unlike conventional metals, making\nTaSe$_2$ an excellent hot electron injector. Finally, we show a vertical\nTaSe$_2$/MoS$_2$/graphene photodetector demonstrating a responsivity of $>10$\nAW$^{-1}$ at $0.1$ MHz - one of the fastest reported photodetectors using\nMoS$_2$."
    },
    {
        "anchor": "Direct band gap and strong Rashba effect in van der Waals\n  heterostructures of InSe and Sb single layers: Van der Waals heterostructures formed by stacking different types of 2D\nmaterials are attracting increasing attention due to new emergent physical\nproperties such as interlayer excitons. Recently synthesized atomically thin\nindium selenide (InSe) and antimony (Sb) individually exhibit interesting\nelectronic properties such as high electron mobility in the former and high\nhole mobility in the latter. In this work, we present a first-principles\ninvestigation on the stability and electronic properties of ultrathin bilayer\nheterostructures composed of InSe and Sb single layers. The calculated\nelectronic band structures reveal a direct band gap semiconducting nature of\nthe InSe/Sb heterostructures independent of stacking pattern. Taking spin-orbit\ncoupling into account, we find a large Rashba spin splitting at the bottom of\nconduction band, which originates from the atomic spin-orbit coupling with the\nsymmetry breaking in the heterostructure. The strength of the Rashba spin\nsplitting can be tuned by applying in-plane biaxial strain or an out-of-plane\nexternal electric field. The presence of large Rashba spin splitting together\nwith a suitable band gap in InSe/Sb bilayer heterostructures make them\npromising candidates for spin field-effect transistor and optoelectronic device\napplications.",
        "positive": "Influence of the heterointerface sharpness on exciton recombination\n  dynamics in an ensemble of (In,Al)As/AlAs quantum dots with indirect band-gap: The dynamics of exciton recombination in an ensemble of indirect band-gap\n(In,Al)As/AlAs quantum dots with type-I band alignment is studied. The lifetime\nof confined excitons which are indirect in momentum-space is mainly influenced\nby the sharpness of the heterointerface between the (In,Al)As quantum dot and\nthe AlAs barrier matrix. Time-resolved photoluminescence experiments and\ntheoretical model calculations reveal a strong dependence of the exciton\nlifetime on the thickness of the interface diffusion layer. The lifetime of\nexcitons with a particular optical transition energy varies because this energy\nis obtained for quantum dots differing in size, shape and composition. The\ndifferent exciton lifetimes, which result in photoluminescence with\nnon-exponential decay obeying a power-law function, can be described by a\nphenomenological distribution function, which allows one to explain the\nphotoluminescence decay with one fitting parameter only."
    },
    {
        "anchor": "Exciton-Plasmon Coupling in Carbon Nanotubes: We study theoretically the interactions of excitonic states with surface\nelectromagnetic modes of small-diameter (~1 nm) semiconducting single-walled\ncarbon nanotubes. We show that these interactions can result in strong\nexciton-surface-plasmon coupling. The exciton absorption lineshapes exhibit the\nline (Rabi) splitting $~0.1-0.3$ eV as the exciton energy is tuned to the\nnearest interband surface plasmon resonance of the nanotube. We expect this\neffect to open a path to new optoelectronic device applications of\nsemiconducting carbon nanotubes.",
        "positive": "Chiral separation and chiral magnetic effects in a slab: The role of\n  boundaries: We study the chiral separation and chiral magnetic effects in a slab of Dirac\nsemimetal of finite thickness, placed in a constant magnetic field\nperpendicular to its surfaces. We utilize the Bogolyubov boundary conditions\nwith a large Dirac mass (band gap) outside the slab. We find that, in a finite\nthickness slab, the axial current density is induced by helicity-correlated\nstanding waves and, as a consequence, is quantized. The quantization is seen in\nits stepped-shape dependence on the fermion chemical potential and a\nsawtooth-shape dependence on the thickness of the slab. In contrast to a naive\nexpectation, there is no chiral charge accumulation anywhere in the bulk or at\nthe boundaries of the semimetal. In the same slab geometry, we also find that a\nnonzero chiral chemical potential induces no electric current, as might have\nbeen expected from the chiral magnetic effect. We argue that this outcome is\nnatural and points to the truly non-static nature of the latter. By taking into\naccount a nonzero electric field of a double layer near the boundaries of the\nslab, we find that the low-energy modes under consideration satisfy the\ncontinuity equation for axial current density without the anomalous term."
    },
    {
        "anchor": "Quasi-ballistic thermal transport across MoS$_2$ thin films: Layered two-dimensional (2D) materials have highly anisotropic thermal\nproperties between the in-plane and cross-plane directions. In general, it is\nthought that cross-plane thermal conductivities ($\\kappa_z$) are low, and\ntherefore c-axis phonon mean free paths (MFPs) are small. Here, we measure\n$\\kappa_z$ across MoS$_2$ films of varying thickness (20 to 240 nm) and uncover\nevidence of very long c-axis phonon MFPs at room temperature in these layered\nsemiconductors. Experimental data obtained using time-domain thermoreflectance\n(TDTR) are in good agreement with first-principles density functional theory\n(DFT). These calculations reveal that ~50% of the heat is carried by phonons\nwith MFP >200 nm, exceeding kinetic theory estimates by nearly two orders of\nmagnitude. Because of quasi-ballistic effects, the $\\kappa_z$ of nanometer thin\nfilms of MoS$_2$ scales with their thickness and the volumetric thermal\nresistance asymptotes to a non-zero value, ~10 m$^{2}$KGW$^{-1}$. This\ncontributes as much as 30% to the total thermal resistance of a 20 nm thick\nfilm, the rest being limited by thermal interface resistance with the SiO$_2$\nsubstrate and top-side aluminum transducer. These findings are essential for\nunderstanding heat flow across nanometer-thin films of MoS$_2$ for\noptoelectronic and thermoelectric applications.",
        "positive": "Population inversion in Landau-quantized graphene: Landau level lasers have the advantage of tunability of the laser frequency\nby means of the external magnetic field. The crucial prerequisite of such a\nlaser is a population inversion between optically coupled Landau levels.\nEfficient carrier-carrier and carrier-phonon scattering generally suppresses\nthis effect in conventional materials. Based on microscopic calculations, we\npredict for the first time the occurrence of a long-lived population inversion\nin Landau-quantized graphene and reveal the underlying many-particle\nmechanisms. To guide the experimental demonstration, we present optimal\nconditions for the observation of a maximal population inversion in terms of\nexperimentally accessible parameters, such as the strength of the magnetic\nfield, pump fluence, temperature, and doping. We reveal that in addition to the\ntunability of the Landau-level laser frequency, also the polarization of the\nemitted light can be tuned via gate voltage controlling the doping of the\nsample."
    },
    {
        "anchor": "Observation of the spin Nernst effect: The observation of the spin Hall effect triggered intense research on pure\nspin current transport. With the spin Hall effect, the spin Seebeck effect, and\nthe spin Peltier effect already observed, our picture of pure spin current\ntransport is almost complete. The only missing piece is the spin Nernst\n(-Ettingshausen) effect, that so far has only been discussed on theoretical\ngrounds. Here, we report the observation of the spin Nernst effect. By applying\na longitudinal temperature gradient, we generate a pure transverse spin current\nin a Pt thin film. For readout, we exploit the\nmagnetization-orientation-dependent spin transfer to an adjacent Yttrium Iron\nGarnet layer, converting the spin Nernst current in Pt into a controlled change\nof the longitudinal thermopower voltage. Our experiments show that the spin\nNernst and the spin Hall effect in Pt are of comparable magnitude, but differ\nin sign, as corroborated by first-principles calculations.",
        "positive": "Giant Rydberg excitons in Cu$_{2}$O probed by photoluminescence\n  excitation spectroscopy: Rydberg excitons are, with their ultrastrong mutual interactions, giant\noptical nonlinearities, and very high sensitivity to external fields, promising\nfor applications in quantum sensing and nonlinear optics at the single-photon\nlevel. To design quantum applications it is necessary to know how Rydberg\nexcitons and other excited states relax to lower-lying exciton states. Here, we\npresent photoluminescence excitation spectroscopy as a method to probe\ntransition probabilities from various excitonic states in cuprous oxide, and we\nshow giant Rydberg excitons at $T=38$ mK with principal quantum numbers up to\n$n=30$, corresponding to a calculated diameter of 3 $\\mu$m."
    },
    {
        "anchor": "Electron-Tunneling-Assisted Non-Abelian Braiding of Rotating Majorana\n  Bound States: It has been argued that fluctuations of fermion parity are harmful for the\ndemonstration of non-Abelian anyonic statistics. Here, we demonstrate a\nstriking exception in which such fluctuations are actively used. We present a\ntheory of coherent electron transport from a tunneling tip into a Corbino\ngeometry Josephson junction where four Majorana bound states (MBSs) rotate.\nWhile the MBSs rotate, electron tunneling happens from the tip to one of the\nMBSs thereby changing the fermion parity of the MBSs. The tunneling events in\ncombination with the rotation allow us to identify a novel braiding operator\nthat does not commute with the braiding cycles in the absence of tunneling,\nrevealing the non-Abelian nature of MBSs. The time-averaged tunneling current\nexhibits resonances as a function of the tip voltage with a period that is a\ndirect consequence of the interference between the non-commuting braiding\noperations. Our work opens up a possibility for utilizing parity non-conserving\nprocesses to control non-Abelian states.",
        "positive": "Monolayer Phosphorene-Metal Interfaces: Recently, phosphorene electronic and optoelectronic prototype devices have\nbeen fabricated with various metal electrodes. We systematically explore for\nthe first time the contact properties of monolayer (ML) phosphorene with a\nseries of commonly used metals (Al, Ag. Cu, Au, Cr, Ni, Ti, and Pd) via both ab\ninitio electronic structure calculations and more reliable quantum transport\nsimulations. Strong interactions are found between all the checked metals, with\nthe energy band structure of ML phosphorene destroyed. In terms of the quantum\ntransport simulations, ML phosphorene forms a n-type Schottky contact with Au,\nCu, Cr, Al, and Ag electrodes, with electron Schottky barrier heights (SBHs) of\n0.30, 0.34, 0.37, 0.51, and 0.52 eV, respectively, and p-type Schottky contact\nwith Ti, Ni, and Pd electrodes, with hole SBHs of 0.30, 0.26, and 0.16 eV,\nrespectively. These results are in good agreement with available experimental\ndata. Our findings not only provide an insight into the ML phosphorene-metal\ninterfaces but also help in ML phosphorene based device design."
    },
    {
        "anchor": "Magnetic properties of carbon nanodisk and nanocone powders: We have investigated the magnetic properties of carbon powders which consist\nof nanodisks, nanocones, and a small fraction of carbon-black particles.\nMagnetization measurements were carried out using a superconducting quantum\ninterference device in magnetic fields $-5<\\mu_{0}H<5\\:\\mathrm{T}$ for\ntemperatures in the range $2\\leq T<350\\:\\mathrm{K}$. Measurements of the\nmagnetization $M$ versus temperature $T$ and magnetic field $\\mu_{0}H$ for\nthese carbon samples show diamagnetism and paramagetism with an additional\nferromagnetic contribution. The ferromagnetic magnetization is in agreement\nwith the calculated magnetization from Fe impurities as determined by the\nparticle-induced x-ray emission method ($<75\\:\\mu\\mathrm{g/g}$). Magnetization\nmeasurements in weak magnetic fields show thermal hysteresis, and for strong\nfields the magnetization $M$ decreases as $M\\sim aT^{-\\alpha}$ with $\\alpha<1$,\nwhich is slower than the Curie law ($\\alpha=1$), when the temperature\nincreases. The magnetization $M$ versus magnetic field $\\mu_{0}H$ shows\nparamagnetic free-spin $S=\\frac{1}{2}$ and $\\frac{3}{2}$ behaviors for\ntemperatures $T=2\\:\\mathrm{K}$ and $15\\leq T\\leq50\\:\\mathrm{K}$, respectively.\nA tendency for localization of electrons was found by electron spin resonance\nwhen the temperature $T$ decreases ($2<T<40\\:\\mathrm{K}$). The magnetic\nproperties in these carbon cone and disk powder samples are more complex than a\nfree-spin model predicts, which is apparently valid only for the temperature\n$T=2\\:\\mathrm{K}$.",
        "positive": "Chiral Metal as a Heisenberg Ferromagnet: The two dimensional surface of an integer quantum hall multilayer is mapped\nonto a Heisenberg spin-chain with ferromagnetic coupling. Using this mapping it\nis shown non-perturbatively that the surface states constitute a very\nanisotropic metal in the infinite size limit. For multilayers of finite size,\ntwo diffusive mesoscopic regimes are identified and the conductance\nfluctuations are calculated perturbatively for both. The Heisenberg spin-chain\nrepresentation is used to study the directed wave problem and the exact result\nis obtained that the mean-square deflection of a directed wave grows as the\nsquare root of the propagation of the distance."
    },
    {
        "anchor": "Disorder-induced tail states in a gapped bilayer graphene: The instanton approach to the in-gap fluctuation states is applied to the\nspectrum of biased bilayer graphene. It is shown that the density of states\nfalls off with energy measured from the band-edge as $\\nu(\\epsilon)\\propto\n\\exp(-|\\epsilon/\\epsilon_t|^{3/2})$, where the characteristic tail energy,\n$\\epsilon_t$, scales with the concentration of impurities, $n_i$, as\n$n_i^{2/3}$. While the bare energy spectrum is characterized by two energies:\nthe bias-induced gap, $V$, and interlayer tunneling, $t_{\\perp}$, the tail,\n$\\epsilon_t$, contains a {\\it single} combination $V^{1/3}t_{\\perp}^{2/3}$. We\nshow that the above expression for $\\nu(\\epsilon)$ in the tail actually applies\nall the way down to the mid-gap.",
        "positive": "Exactly unsolved problems of interacting 1D fermions: Applications of the integrable system techniques to the non-equilibrium\ntransport problems are discussed. We describe one-dimensional electrons\ntunneling through a point-like defect either by the s-d exchange (Kondo)\nmechanism, or via the resonanse level (Anderson) mechanism. These models are\npotential candidates to be solved exactly in the presence of arbitrary external\nbias. We draw attention also to several mesoscopical systems which can be\ntackled by the massless form-factor approach, as perturbations of integrable\nmodels. The basic unperturbed model is the massless sine-Gordon model with the\ninteraction (cosine) term restricted to one point, which is integrable. It is\nbeing perturbed by the second interaction term, which destroys integrability.\nQuasi-exact results can be obtained by making use of the basis of massless\nquasiparticles of the sine-Gordon model."
    },
    {
        "anchor": "Plasmon-emitter interaction using integrated ring grating-nanoantenna\n  structures: Overcoming the diffraction limit to achieve high optical resolution is one of\nthe main challenges in the fields of plasmonics, nanooptics and nanophotonics.\nIn this work, we introduce novel plasmonic structures consisting of\nnanoantennas (nanoprisms, single bowtie nanoantennas and double bowtie\nnanoantennas) integrated in the center of ring diffraction gratings.\nPropagating surface plasmon polaritons (SPPs) are generated by the ring grating\nand coupled with localized surface plasmons (LSPs) at the nanoantennas exciting\nemitters placed in their gap. SPPs are widely used for optical waveguiding but\nprovide low resolution due to their weak spatial confinement. Oppositely, LSPs\nprovide excellent sub-wavelength confinement but induce large losses. The\nphenomenon of SPP-LSP coupling witnessed in our structures allows achieving\nmore precise focusing at the nanoscale, causing an increase in the fluorescence\nemission of the emitters. FDTD simulations as well as experimental fabrication\nand optical characterization results are presented to study plasmon-emitter\ncoupling between an ensemble of dye molecules and our integrated plasmonic\nstructures. A comparison is given to highlight the importance of each structure\non the photoluminescence and radiative decay enhancement of the molecules.",
        "positive": "Photoluminescent properties of the carbon-dimer defect in hexagonal\n  boron-nitride: a many-body finite-size cluster approach: We study the carbon dimer defect in a hexagonal boron-nitride monolayer using\nthe GW and Bethe-Salpeter many-body perturbation theories within a finite size\ncluster approach. While quasiparticle energies converge very slowly with system\nsize due to missing long-range polarization effects, optical excitations\nconverge much faster, with a $1/R^3$ scaling law with respect to cluster\naverage radius. We obtain a luminescence zero-phonon energy of 4.36 eV,\nincluding significant 0.13 eV zero-point vibrational energy and 0.15 eV\nreorganization energy contributions. Inter-layer screening decreases further\nthe emission energy by about 0.3 eV. These results bring support to the recent\nidentification of the substitutional carbon dimer as the likely source of the\nzero-phonon 4.1 eV luminescence line. Finally, the GW quasiparticle energies\nare extrapolated to the infinite h-BN monolayer limit, leading to a predicted\ndefect HOMO-LUMO photoemission gap of 7.6 eV. Comparison with the optical gap\nyields a very large excitonic binding energy of 3 eV for the associated\nlocalized Frenkel exciton."
    },
    {
        "anchor": "Nuclear Polarization in Quantum Point Contacts in an In-Plane Magnetic\n  Field: Nuclear spin polarization is typically generated in GaAs quantum point\ncontacts (QPCs) when an out-of-plane magnetic field gives rise to\nspin-polarized quantum Hall edge states, and a voltage bias drives transitions\nbetween the edge states via electron-nuclear flip-flop scattering. Here, we\nreport a similar effect for QPCs in an in-plane magnetic field, where currents\nare spin polarized but edge states are not formed. The nuclear polarization\ngives rise to hysteresis in the d.c. transport characteristics, with relaxation\ntimescales around 100 seconds. The dependence of anomalous QPC conductance\nfeatures on nuclear polarization provides a useful test of their\nspin-sensitivity.",
        "positive": "Chaotic scattering with direct processes: A generalization of Poisson's\n  kernel for non-unitary scattering matrices: The problem of chaotic scattering in presence of direct processes or prompt\nresponses is mapped via a transformation to the case of scattering in absence\nof such processes for non-unitary scattering matrices, \\tilde S. In the absence\nof prompt responses, \\tilde S is uniformly distributed according to its\ninvariant measure in the space of \\tilde S matrices with zero average, < \\tilde\nS > =0. In the presence of direct processes, the distribution of \\tilde S is\nnon-uniform and it is characterized by the average < \\tilde S > (\\neq 0). In\ncontrast to the case of unitary matrices S, where the invariant measures of S\nfor chaotic scattering with and without direct processes are related through\nthe well known Poisson kernel, here we show that for non-unitary scattering\nmatrices the invariant measures are related by the Poisson kernel squared. Our\nresults are relevant to situations where flux conservation is not satisfied.\nFor example, transport experiments in chaotic systems, where gains or losses\nare present, like microwave chaotic cavities or graphs, and acoustic or elastic\nresonators."
    },
    {
        "anchor": "Non-local transport via edge-states in InAs/GaSb coupled quantum wells: We have investigated low-temperature electronic transport on InAs/GaSb double\nquantum wells, a system which promises to be electrically tunable from a normal\nto a topological insulator. Hall bars of $50\\,\\mu$m in length down to a few\n$\\mu$m gradually develop a pronounced resistance plateau near\ncharge-neutrality, which comes along with distinct non-local transport along\nthe edges. Plateau resistances are found to be above or below the quantized\nvalue expected for helical edge channels. We discuss these results based on the\ninterplay between imperfect edges and residual local bulk conductivity.",
        "positive": "Time-Resolved Open-Circuit Conductive Atomic Force Microscopy for\n  Quantitative Analysis of Nanowire Piezoelectricity and Triboelectricity: Piezoelectric nanowires are promising materials for sensing, actuation and\nenergy harvesting, due to their enhanced properties at the nanoscale. However,\nquantitative characterization of piezoelectricity in nanomaterials is\nchallenging due to practical limitations and the onset of additional\nelectromechanical phenomena, such as the triboelectric and piezotronic effects.\nHere, we present an open-circuit conductive atomic force microscopy (cAFM)\nmethodology for quantitative extraction of the axial piezoelectric coefficients\nof nanowires. We show, both theoretically and experimentally, that the standard\nshort-circuit cAFM mode is inadequate for piezoelectric characterization of\nnanowires, and that such measurements are governed by competing mechanisms. We\nintroduce an alternative open-circuit configuration, and employ time-resolved\nelectromechanical measurements, to extract the piezoelectric coefficients. This\nmethod was applied to GaAs, an important semiconductor, with relatively low\npiezoelectric coefficients. The results obtained for GaAs,~0.4-1 pm/V, are in\ngood agreement with existing knowledge and theory. Our method represents a\nsignificant advance in understanding the coexistence of different\nelectromechanical effects, and in quantitative piezoelectric nanoscale\ncharacterization. The easy implementation will enable better understanding of\nelectromechanics at the nanoscale."
    },
    {
        "anchor": "Moir\u00e9 Commensurability and the Quantum Anomalous Hall Effect in\n  Twisted Bilayer Graphene on Hexagonal Boron Nitride: The quantum anomalous Hall (QAH) effect is sometimes observed in twisted\nbilayer graphene (tBG) when it is nearly aligned with an encapsulating\nhexagonal boron nitride (hBN) layer. We propose that the appearance or absence\nof the QAH effect in individual devices could be related to commensurability\nbetween the graphene/graphene and graphene/hBN moir\\'e patterns. We identify a\nseries of points in the $(\\theta_{\\rm GG},\\theta_{\\rm GBN})$ twist-angle space\nat which the two moir\\'e patterns are commensurate, allowing moir\\'e band\ntheory to be applied, and show that the band Chern numbers are in this case\nsensitive to a rigid in-plane hBN displacement. Given this property, we argue\nthat the QAH effect is likely only when i) the $(\\theta_{\\rm GG},\\theta_{\\rm\nGBN})$ twist-angle-pair is close enough to a commensurate point that the two\nmoir\\'e patterns yield a supermoir\\'e pattern with a sufficiently long length\nscale, and ii) the supermoir\\'e has a percolating topologically non-trivial QAH\nphase. For twist angles far from commensurability, the hBN layer acts as a\nsource of disorder that can destroy the QAH effect. Our proposal can explain a\nnumber of current experimental observations. Further experimental studies that\ncan test this proposal more directly are suggested.",
        "positive": "Entanglement and thermalization in open fermion systems: We numerically study two non-interacting fermion models, a quantum wire model\nand a Chern insulator model, governed by open system Lindblad dynamics. The\nphysical setup consists of a unitarily evolving \"bulk\" coupled via its\nboundaries to two dissipative \"leads\". The open system dynamics is chosen to\ndrive the leads to thermal equilibrium, and by choosing different temperatures\nand chemical potentials for the two leads we may drive the bulk into a\nnon-equilibrium current carrying steady state. We report two main results in\nthis context. First, we show that for an appropriate choice of dynamics of the\nleads, the bulk state is also driven to thermal equilibrium even though the\nopen system dynamics does not act directly on it. Second, we show that the\nsteady state which emerges at late time, even in the presence of currents, is\nlightly entangled in the sense of having small mutual information and\nconditional mutual information for appropriate regions. We also report some\nresults for the rate of approach to the steady state. These results have\nbearing on recent attempts to formulate a numerically tractable method to\ncompute currents in strongly interacting models; specifically, they are\nrelevant for the problem of designing simple leads that can drive a target\nsystem into thermal equilibrium at low temperature."
    },
    {
        "anchor": "Electrostatic interactions in twisted bilayer graphene: The effects of the long range electrostatic interaction in twisted bilayer\ngraphene are described using the Hartree-Fock approximation. The results show a\nsignificant dependence of the band widths and shapes on electron filling, and\nthe existence of broken symmetry phases at many densities, either valley/spin\npolarized, with broken sublattice symmetry, or both.",
        "positive": "Orbital entanglement and electron localization in quantum wires: We study the signatures of disorder in the production of orbital electron\nentanglement in quantum wires. Disordered entanglers suffer the effects of\nlocalization of the electron wave function and random fluctuations in the\nentanglement production. This manifests in the statistics of the concurrence, a\nmeasure of the produced two-qubit entanglement. We calculate the concurrence\ndistribution as a function of the disorder strength within a random-matrix\napproach. We also identify significant constraints on the entanglement\nproduction as a consequence of the breaking/preservation of time-reversal\ninvariance. Additionally, our theoretical results are independently supported\nby simulations of disordered quantum wires based on a tight-binding model."
    },
    {
        "anchor": "Uncovering the Triplet Ground State of Triangular Graphene Nanoflakes\n  Engineered with Atomic Precision on a Metal Surface: Graphene can develop large magnetic moments in custom crafted open-shell\nnanostructures such as triangulene, a triangular piece of graphene with zigzag\nedges. Current methods of engineering graphene nano-systems on surfaces\nsucceeded in producing atomically precise open-shell structures, but\ndemonstration of their net spin remains elusive to date. Here, we fabricate\ntriangulene-like graphene systems and demonstrate that they possess a spin\n$S=1$ ground state. Scanning tunnelling spectroscopy identifies the fingerprint\nof an underscreened $S=1$ Kondo state on \\rev{these} flakes at low\ntemperatures, signaling the dominant ferromagnetic interactions between two\nspins. Combined with simulations based on the meanfield Hubbard model, we show\nthat this $S=1$ $\\pi$-paramagnetism is robust, and can be manipulated to a\n$S=1/2$ state by adding additional H-atoms to the radical sites. \\rev{Our\nresults demonstrate that $\\pi$-paramagnetism of high-spin graphene flakes can\nsurvive on surfaces, opening the door to study the quantum behaviour of\ninteracting $\\pi$-spins in graphene systems.",
        "positive": "Gyrotropy and magneto-spatial dispersion effects at intersubband\n  transitions in quantum wells: Gyrotropic properties of multiple quantum well structures are studied\ntheoretically. Symmetry analysis is performed yielding the gyrotropy tensor\ncomponents for structures grown along [001], [110] and [311] crystallographic\ndirections. Angular dependences of circular dichroism and natural optical\nactivity signals are established. Phenomenological model and microscopic theory\nbased on spin-orbit splitting of size-quantized subbands are developed for\nphoton energies close to the energy of the intersubband optical transition.\nMagneto-spatial dispersion effects arising from the diamagnetic shift of the\nintersubband energy gap linear in the electron momentum are also considered. It\nis demonstrated that the spectral dependence of the gyrotropy and\nmagneto-spatial dispersion constants represents an asymmetrical peak with a\ndegree of asymmetry governed by the mean electron energy. The estimates show\nthat the considered effects are detectable in experiments."
    },
    {
        "anchor": "Photo-induced, non-equilibrium spin and charge polarization in quantum\n  rings: We investigate the spin-dependent dynamical response of a quantum ring with a\nspin-orbit interaction upon the application of linearly polarized, picosecond,\nasymmetric electromagnetic pulses. The oscillations of the generated dipole\nmoment are sensitive to the parity of the occupation number in the ring and to\nthe strength of the spin-orbit coupling. It is shown how the associated\nemission spectrum can be controlled via the pulse strength or a gate voltage.\nIn addition, we inspect how a static magnetic flux can modify the\nnon-equilibrium dynamics. In presence of the spin-orbit interaction and for a\nparamagnetic ring, the applied pulse results in a spin-split, non-equilibrium\nlocal charge density. The resulting temporal spin polarization is directed\nperpendicular to the light-pulse polarization axis and oscillates periodically\nwith the frequency of the spin-split charge density. The spin-averaged\nnon-equilibrium charge density possesses a left-right symmetry with respect to\nthe pulse polarization axis. The calculations presented here are applicable to\nnano-meter rings fabricated in heterojuctions of III-V and II-VI semiconductors\ncontaining several hundreds electrons.",
        "positive": "Direct and indirect exciton mixing in a slightly asymmetric double\n  quantum well: We studied, theoretically, the optical absorption spectra for a slightly\nasymmetric double quantum well (DQW), in the presence of electric and magnetic\nfields. Recent experimental results for a 10.18/3.82/9.61 nm GaAs Al(_{.33}\n)Ga(_{.67})As DQW show clearly the different behavior in the luminescence peaks\nfor the indirect exciton (IX) and left direct exciton (DX) as a function of the\nexternal electric field. We show that the presence of a peak near the (DX)\npeak, attributed to an impurity bound left (DX) in the experimental results,\ncould be a consequence of the non-trivial mixing between excitonic states."
    },
    {
        "anchor": "Many-terminal Majorana island: from Topological to Multi-Channel Kondo\n  Model: We study Kondo screening obtained by coupling Majorana bound states, located\non a topological superconducting island, to interacting electronic reservoirs.\nAt the charge degeneracy points of the island, we formulate an exact mapping\nonto the spin-$1/2$ multi-channel Kondo effect. The coupling to Majorana\nfermions transforms the tunneling terms into effective fermionic bilinear\ncontributions with a Luttinger parameter $K$ in the leads that is effectively\ndoubled. For strong interaction, $K=1/2$, the intermediate fixed point of the\nstandard multi-channel Kondo model is exactly recovered. It evolves with $K$\nand connects to strong coupling in non-interacting case $K=1$, with maximum\nconductance between the leads and robustness against channel asymmetries\nsimilarly to the topological Kondo effect. For a number of leads above four,\nthere exists a window of Luttinger parameters in which a quantum phase\ntransition can occur between the strong coupling topological Kondo state and\nthe partially conducting multi-channel Kondo state.",
        "positive": "Charge-state lifetimes of single molecules on ultrathin insulating films: In scanning tunneling microscopy (STM) experiments of molecules on insulating\nfilms, tunneling through molecular resonances implies transiently charging the\nmolecule. The transition back to the charge ground state by tunneling through\nthe insulating film is crucial, for example, for understanding STM-induced\nelectroluminescence. Here, using STM, we report on the charge-state lifetimes\nof individual molecules adsorbed on NaCl films of different thicknesses on\nCu(111) and Au(111). To that end, we approached the tip to the molecule at\nresonant tunnel conditions up to a regime where charge transport was limited by\ntunneling through the NaCl film. The resulting saturation of tunnel current is\na direct measure of the molecule's charge-state lifetime, thus providing a\nmeans to study charge dynamics and, thereby, exciton dynamics. Comparison of\nanion and cation lifetimes on different substrates reveals the critical role of\nthe level alignment with the insulator's conduction and valence band, and the\nmetal-insulator interface state."
    },
    {
        "anchor": "Wide-band capacitance measurement on a semiconductor double quantum dot\n  for studying tunneling dynamics: We propose and demonstrate wide-band capacitance measurements on a\nsemiconductor double-quantum dot (DQD) to study tunneling dynamics. By applying\nphase-tunable high-frequency signals independently to the DQD and a nearby\nquantum-point-contact charge detector, we perform on-chip lock-in detection of\nthe capacitance associated with the single-electron motion over a wide\nfrequency range from hertz to a few ten gigahertz. Analyzing the phase and the\nfrequency dependence of the signal allows us to extract the characteristic\ntunneling rates. We show that, by applying this technique to the interdot\ntunnel coupling regime, quantum capacitance reflecting the strength of the\nquantum-mechanical coupling can be measured.",
        "positive": "Cu_{2}O as nonmagnetic semiconductor for spin transport in crystalline\n  oxide electronics: We probe spin transport in Cu_{2}O by measuring spin valve effect in\nLa_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co and\nLa_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/La_{0.7}Sr_{0.3}MnO_{3} epitaxial\nheterostructures. In La_{0.7}Sr_{0.3}MnO_{3}/Cu_{2}O/Co systems we find that a\nfraction of out-of-equilibrium spin polarized carrier actually travel across\nthe Cu_{2}O layer up to distances of almost 100 nm at low temperature. The\ncorresponding spin diffusion length dspin is estimated around 40 nm.\nFurthermore, we find that the insertion of a SrTiO_{3} tunneling barrier does\nnot improve spin injection, likely due to the matching of resistances at the\ninterfaces. Our result on dspin may be likely improved, both in terms of\nCu_{2}O crystalline quality and sub-micrometric morphology and in terms of\ndevice geometry, indicating that Cu_{2}O is a potential material for efficient\nspin transport in devices based on crystalline oxides."
    },
    {
        "anchor": "Magnetostatics of Magnetic Skyrmion Crystals: Magnetic skyrmion crystals are topological magnetic textures arising in the\nchiral ferromagnetic materials with Dzyaloshinskii-Moriya interaction. The\nmagnetostatic fields generated by magnetic skyrmion crystals are first studied\nby micromagnetic simulations. For N\\'eel-type skyrmion crystals, the fields\nwill vanish on one side of the crystal plane, which depend on the helicity;\nwhile for Bloch-type skyrmion crystals, the fields will distribute over both\nsides, and are identical for the two helicities. These features and the\nsymmetry relations of the magetostatic fields are understood from the magnetic\nscalar potential and magnetic vector potential of the hybridized triple-Q\nstate. The possibility to construct magnetostatic field at nanoscale by\nstacking chiral ferromagnetic layers with magnetic skyrmion crystals is also\ndiscussed, which may have potential applications to trap and manipulate neutral\natoms with magnetic moments.",
        "positive": "Trigonal warping, pseudodiffusive transport, and finite-system version\n  of the Lifshitz transition in magnetoconductance of bilayer-graphene Corbino\n  disks: Using the transfer matrix in the angular-momentum space we investigate the\nimpact of trigonal warping on magnetotransport and scaling properties of a\nballistic bilayer graphene in the Corbino geometry. Although the conductivity\nat the charge-neutrality point and zero magnetic field exhibits a one-parameter\nscaling, the shot-noise characteristics, quantified by the Fano factor\n$\\mathcal{F}$ and the third charge-transfer cumulant $\\mathcal{R}$, remain\npseudodiffusive. This shows that the pseudodiffusive transport regime in\nbilayer graphene is not related to the universal value of the conductivity but\ncan be identified by higher charge-transfer cumulants. For Corbino disks with\nlarger radii ratios the conductivity is suppressed by the trigonal warping,\nmainly because the symmetry reduction amplifies backscattering for normal modes\ncorresponding to angular-momentum eigenvalues $\\pm{}2\\hbar$. Weak magnetic\nfields enhance the conductivity, reaching the maximal value near the crossover\nfield $B_L=\\frac{4}{3}\\sqrt{3}\\,({\\hbar}/{e})\\,t't_\\perp\\!\\left[{t_0^2a(R_{\\rm\no}-R_{\\rm i})}\\right]^{-1}$, where $t_0$ ($t_\\perp$) is the nearest-neighbor\nintra- (inter-)layer hopping integral, $t'$ is the skew-interlayer hopping\nintegral, and $R_{\\rm o}$ ($R_{\\rm i}$) is the outer (inner) disk radius. For\nmagnetic fields $B\\gtrsim{}B_L$ we observe quasiperiodic conductance\noscillations characterized by the decreasing mean value\n$\\langle\\sigma\\rangle-\\sigma_0\\propto{}B_L/B$, where $\\sigma_0=(8/\\pi)\\,e^2/h$.\nThe conductivity, as well as higher charge-transfer cumulants, show beating\npatterns with an envelope period proportional to $\\sqrt{B/B_L}$. This\nconstitutes a qualitative difference between the high-field ($B\\gg{}B_L$)\nmagnetotransport in the $t'=0$ case (earlier discussed in Ref. [1]) and in the\n$t'\\neq{}0$ case, providing a finite-system analog of the Lifshitz transition."
    },
    {
        "anchor": "Topological Phases in a PT-Symmetric Dissipative Kitaev Chain: We study a topological phase in the dissipative Kitaev chain described by the\nMarkovian quantum master equation. Based on the correspondence between\nLindbladians, which generate the dissipative time-evolution, and non-Hermitian\nmatrices, Lindbladians are classified in terms of non-Hermitian topological\nphases. We find out that the Lindbladian retains PT symmetry which is the\nprominent symmetry of open systems and then all the bulk modes can have a\ncommon lifetime. Moreover, when open boundary conditions are imposed on the\nsystem, the edge modes which break PT symmetry emerge, and one of the edge\nmodes has a zero eigenvalue.",
        "positive": "P-shell carriers assisted dynamic nuclear spin polarization in single\n  quantum dots at zero external magnetic field: Repeated injection of spin polarized carriers in a quantum dot leads to the\npolarization of nuclear spins, a process known as dynamic nuclear spin\npolarization (DNP). Here, we report the first observation of p-shell carrier\nassisted DNP in single QDs at zero external magnetic field. The nuclear field -\nmeasured by using the Overhauser shift of the singly charged exciton state of\nthe QDs - continues to increase, even after the carrier population in the\ns-shell saturates. This is also accompanied by an abrupt increase in nuclear\nspin buildup time as p-shell emission overtakes that of the s-shell. We\nattribute the observation to p-shell electrons strongly altering the nuclear\nspin dynamics in the QD, supported by numerical simulation results based on a\nrate equation model of coupling between electron and nuclear spin system. DNP\nwith p-shell carriers could open up avenues for further control to increase the\ndegree of nuclear spin polarization in QDs."
    },
    {
        "anchor": "Current-Driven Motion of Magnetic Domain Wall with Many Bloch Lines: The current-driven motion of a domain wall (DW) in a ferromagnet with many\nBloch lines (BLs) via the spin transfer torque is studied theoretically. It is\nfound that the motion of BLs changes the current-velocity ($j$-$v$)\ncharacteristic dramatically. Especially, the critical current density to\novercome the pinning force is reduced by the factor of the Gilbert damping\ncoefficient $\\alpha$ even compared with that of a skyrmion. This is in sharp\ncontrast to the case of magnetic field driven motion, where the existence of\nBLs reduces the mobility of the DW.",
        "positive": "Film thickness of Pb islands on the Si(111) surface: We analyze topographic scanning force microscopy images together with Kelvin\nprobe images obtained on Pb islands and on the wetting layer on Si(111) for\nvariable annealing times. Within the wetting layer we observe negatively\ncharged Si-rich areas. We show evidence that these Si-rich areas result from\nislands that have disappeared by coarsening. We argue that the islands are\nlocated on Si-rich areas inside the wetting layer such that the Pb/Si interface\nof the islands is in line with the top of the wetting layer rather than with\nits interface to the substrate. We propose that the Pb island heights are one\natomic layer smaller than previously believed. For the quantum size effect\nbilayer oscillations of the work function observed in this system, we conclude\nthat for film thicknesses below 9 atomic layers large values of the work\nfunction correspond to even numbers of monolayers instead of odd ones. The\natomically precise island height is important to understand ultrafast\n\"explosive\" island growth in this system."
    },
    {
        "anchor": "Tunneling decay in a magnetic field: We provide a semiclassical theory of tunneling decay in a magnetic field and\na three-dimensional potential of a general form. Because of broken\ntime-reversal symmetry, the standard WKB technique has to be modified. The\ndecay rate is found from the analysis of the set of the particle Hamiltonian\ntrajectories in complex phase space and time. In a magnetic field, the\ntunneling particle comes out from the barrier with a finite velocity and behind\nthe boundary of the classically allowed region. The exit location is obtained\nby matching the decaying and outgoing WKB waves at a caustic in complex\nconfiguration space. Different branches of the WKB wave function match on the\nswitching surface in real space, where the slope of the wave function sharply\nchanges. The theory is not limited to tunneling from potential wells which are\nparabolic near the minimum. For parabolic wells, we provide a bounce-type\nformulation in a magnetic field. The theory is applied to specific models which\nare relevant to tunneling from correlated two-dimensional electron systems in a\nmagnetic field parallel to the electron layer.",
        "positive": "Non-linear thermoelectric transport: A class of nano-devices for high\n  efficiency and large power output: Molecular junctions and similar devices described by an energy dependent\ntransmission coefficient can have a high linear response thermoelectric figure\nof merit. Since such devices are inherently non-linear, the full thermodynamic\nefficiency valid for any temperature and chemical potential difference across\nthe leads is calculated. The general features in the energy dependence of the\ntranmission function that lead to high efficiency and also high power output\nare determined. It is shown that the device with the highest efficiency does\nnot necessarily lead to large power output. To illustrate this, we use a model\ncalled the t-stub model representing tunneling through an energy level\nconnected to another energy level. Within this model both high efficiency and\nhigh power output are achievable. Futhermore, by connecting many nanodevices it\nis shown to be possible to scale up the power output without compromising\nefficiency in an (exactly solvable) n-channel model even with tunneling between\nthe devices."
    },
    {
        "anchor": "Single-particle theory of persistent spin helices in two-dimensional\n  electron gas: the general approach for quantum wells with different growth\n  direction: We present a detailed theoretical investigation of persistent spin helices in\ntwo-dimensional electron systems with spin-orbit coupling. For this purpose we\nconsider a single-particle effective mass Hamiltonian with generalized\nlinear-in-k spin-orbit coupling term corresponding to a quantum well grown in\nan arbitrary crystallographic direction, and derive the general condition for\nthe formation of the persistent spin helix. This condition applied for the\nHamiltonians describing quantum wells with different growth directions\nindicates the possibility of existence of the persistent spin helix in a wide\nclass of 2D systems apart from [001] model with equal Rashba and Dresselhaus\nspin-orbit coupling strengths and the [110] Dresselhaus model. In addition, we\nemploy the translation operator formalism for analytical calculation of\nspace-resolved spin density and visualization of the persistent spin helix\npatterns.",
        "positive": "Size effect in ion transport through angstrom-scale slits: It has been an ultimate but seemingly distant goal of nanofluidics to\ncontrollably fabricate capillaries with dimensions approaching the size of\nsmall ions and water molecules. We report ion transport through ultimately\nnarrow slits that are fabricated by effectively removing a single atomic plane\nfrom a bulk crystal. The atomically flat angstrom-scale slits exhibit little\nsurface charge, allowing elucidation of the role of steric effects. We find\nthat ions with hydrated diameters larger than the slit size can still permeate\nthrough, albeit with reduced mobility. The confinement also leads to a notable\nasymmetry between anions and cations of the same diameter. Our results provide\na platform for studying effects of angstrom-scale confinement, which is\nimportant for development of nanofluidics, molecular separation and other\nnanoscale technologies."
    },
    {
        "anchor": "Interface traps in graphene field effect devices: extraction methods and\n  influence on characteristics: We study impact of the near-interfacial oxide traps on the C-V and I-V\ncharacteristics of graphene gated structures. Methods of extraction of\ninterface trap level density in graphene field effect devices from the\ncapacitance-voltage measurements are described and discussed. It has been found\nthat the effects of electron-electron or hole-hole interactions and\nelectron-hole puddles can be mixed in C-V characteristics putting obstacles in\nthe way of uniquely determined extraction of the interface trap density in\ngraphene. Influence of the interface traps on DC and AC capacitance and\nconductance characteristics of graphene field-effect structures is described.\nIt has been shown that variety of widths of resistivity peaks in various\nsamples could be explained by different interface trap capacitance values.",
        "positive": "Quantum Acoustics with Surface Acoustic Waves: It has recently been demonstrated that surface acoustic waves (SAWs) can\ninteract with superconducting qubits at the quantum level. SAW resonators in\nthe GHz frequency range have also been found to have low loss at temperatures\ncompatible with superconducting quantum circuits. These advances open up new\npossibilities to use the phonon degree of freedom to carry quantum information.\nIn this paper, we give a description of the basic SAW components needed to\ndevelop quantum circuits, where propagating or localized SAW-phonons are used\nboth to study basic physics and to manipulate quantum information. Using\nphonons instead of photons offers new possibilities which make these quantum\nacoustic circuits very interesting. We discuss general considerations for SAW\nexperiments at the quantum level and describe experiments both with SAW\nresonators and with interaction between SAWs and a qubit. We also discuss\nseveral potential future developments."
    },
    {
        "anchor": "Radiative Heat Transfer between Neighboring Particles: The near-field interaction between two neighboring particles is known to\nproduce enhanced radiative heat transfer. We advance in the understanding of\nthis phenomenon by including the full electromagnetic particle response, heat\nexchange with the environment, and important radiative corrections both in the\ndistance dependence of the fields and in the particle absorption coefficients.\nWe find that crossed terms of electric and magnetic interactions dominate the\ntransfer rate between gold and SiC particles, whereas radiative corrections\nreduce it by several orders of magnitude even at small separations. Radiation\naway from the dimer can be strongly suppressed or enhanced at low and high\ntemperatures, respectively. These effects must be taken into account for an\naccurate description of radiative heat transfer in nanostructured environments.",
        "positive": "Wave packet dynamics and zitterbewegung of heavy holes in a quantizing\n  magnetic field: In this work we study wave packet dynamics and $zitterbewegung$, an\noscillatory quantum motion, of heavy holes in III-V semiconductor quantum wells\nin presence of a quantizing magnetic field. It is revealed that a Gaussian\nwave-packet describing a heavy hole diffuses asymmetrically along the circular\norbit while performing cyclotron motion. The wave packet splits into two peaks\nwith unequal amplitudes after a certain time depending on spin-orbit coupling\nconstant. This unequal splitting of the wave packet is attributed to the cubic\nRashba interaction for heavy holes. The difference in the peak amplitudes\ndisappears with time. At a certain time the two peaks diffuse almost along the\nentire cyclotron orbit. Then tail and head of the diffused wave packet\ninterfere and as a result a completely randomized pattern of the wave packet is\nobserved. The diffusion rate of the wave packet increases with increase of the\nspin-orbit interaction strength. Also strong spin-orbit coupling expedite the\nsplitting and the randomization of the wave packet. We also study the\n$zitterbewegung$ in various physical observables such as position, charge\ncurrent and spin angular momentum of the heavy hole. The $zitterbewegung$\noscillations are very much sensitive to the initial wave vector of the Gaussian\nwave packet and the strength of the Rashba spin-orbit coupling."
    },
    {
        "anchor": "Hanbury-Brown and Twiss exchange effects in a four-terminal tunnel\n  junction: We investigate the current-current correlations in a four-terminal Al-AlOx-Al\ntunnel junction where shot noise dominates. We demonstrate that\ncross-correlations in the presence of two biasing sources of the Hanbury-Brown\nand Twiss type are much stronger (approximately twice) than an incoherent sum\nof correlations generated by single sources. The difference is due to voltage\nfluctuations of the central island that give rise to current-current\ncorrelations in the four contacts of the junction. Our measurements are in\nclose agreement with results obtained using a simple theoretical model based on\nthe theory of shot noise in multi-terminal conductors, generalized here to\narbitrary contacts.",
        "positive": "High resolution dynamic imaging of the delay- and tilt-free motion of\n  N\u00e9el domain walls in perpendicularly magnetized superlattices: We report on the time-resolved investigation of current- and field-induced\ndomain wall motion in perpendicularly magnetized microwires exhibiting\nasymmetric exchange interaction by means of scanning transmission x-ray\nmicroscopy using a time step of 200 ps. Dynamical domain wall velocities on the\norder of 50-100 m s$^{-1}$ were observed. The improvement in the temporal\nresolution allowed us to observe the absence of incubation times for the motion\nof the domain wall, together with indications for a negligible inertia.\nFurthermore, we observed that, for short current and magnetic field pulses, the\nmagnetic domain walls do not exhibit a tilting during its motion, providing a\nmechanism for the fast, tilt-free, motion of magnetic domain walls."
    },
    {
        "anchor": "Theoretical analysis of injection driven thermal light emitters based on\n  graphene encapsulated by hexagonal boron nitride: We develop the device model for the proposed injection (electrically) driven\nthermal light emitters (IDLEs) based on the vertical Hexagonal Boron Nitride\nLayer/Graphene Layer/ Hexagonal Boron Nitride Layer (hBNL/GL/hBNL)\nheterostructures and analyze their dynamic response. The operation of the IDLEs\nis associated with the light emission of the hot two-dimensional electron-hole\nplasma (2DEHP) generated in the GL by both the lateral injection from the side\ncontacts and the vertical injection through the hBNL (combined injection)\nheating the 2DEHP. The temporal variation of the injection current results in\nthe variation of the carrier effective temperature and their density in the GL\nleading to the modulation of the output light. We determine the mechanisms\nlimiting the IDLE efficiency and the maximum light modulation frequency. A\nlarge difference between the carrier and lattice temperatures the IDLEs with an\neffective heat removal enables a fairly large modulation depth at the\nmodulation frequencies about dozen of GHz in contrast to the standard\nincandescent lamps. We compare the IDLEs with the combined injection under\nconsideration and IDLEs using the carrier Joule heating by lateral current.\n  The obtained results can be used for the IDLE optimization.",
        "positive": "Non-Markovian transients in transport across chiral quantum wires using\n  space-time non-equilibrium Green functions: We study a system of two non-interacting quantum wires with fermions of\nopposite chirality with a point contact junction at the origin across which\ntunneling can take place when an arbitrary time-dependent bias between the\nwires is applied. We obtain the exact dynamical non-equilibrium Green function\nby solving Dyson's equation analytically. Both the space-time dependent two and\nfour-point functions are written down in a closed form in terms of simple\nfunctions of position and time. This allows us to obtain, among other things,\nthe I-V characteristics for an arbitrary time-dependent bias. Our method is a\nsuperior alternative to competing approaches to non-equilibrium as we are able\nto account for transient phenomena as well as the steady state. We study the\napproach to steady state by computing the time evolution of the equal-time\none-particle Green function. Our method can be easily applied to the problem of\na double barrier contact whose internal properties can be adjusted to induce\nresonant tunneling leading to a conductance maximum. We then consider the case\nof a finite bandwidth in the point contact and calculate the non-equilibrium\ntransport properties which exhibit non-Markovian behaviour. When a subsequently\nconstant bias is suddenly switched on, the current shows a transient build up\nbefore approaching its steady state value in contrast to the infinite bandwidth\ncase. This transient property is consistent with numerical simulations of\nlattice systems using time-dependent DMRG (tDMRG) suggesting thereby that this\ntransient build up is merely due to the presence of a short distance cutoff in\nthe problem description and not on the other details."
    },
    {
        "anchor": "Quantum Dragon Solutions for Electron Transport through Nanostructures\n  based on Rectangular Graphs: Electron transport through nanodevices of atoms in a single-layer rectangular\narrangement with free (open) boundary conditions parallel to the direction of\nthe current flow is studied within the single-band tight binding model. The\nLandauer formula gives the electrical conductance to be a function of the\nelectron transmission probability, ${\\cal T}(E)$, as a function of the energy\n$E$ of the incoming electron. A quantum dragon nanodevice is one which has a\nperfectly conducting channel, namely ${\\cal T}(E)=1$ for all energies which are\ntransmitted by the external leads even though there may be arbitrarily strong\nelectron scattering. The rectangular single-layer systems are shown to be able\nto be quantum dragon devices, both for uniform leads and for dimerized leads.\nThe quantum dragon condition requires appropriate lead-device connections and\ncorrelated randomness in the device.",
        "positive": "Yu-Shiba-Rusinov bands in a self-assembled kagome lattice of magnetic\n  molecules: Kagome lattices constitute versatile platforms for studying paradigmatic\ncorrelated phases. While molecular self-assembly of kagome structures on\nmetallic substrates is promising, it is challenging to realize pristine kagome\nproperties because of hybridization with the bulk degrees of freedom and\nmodified electron-electron interactions. We suggest that a superconducting\nsubstrate offers an ideal support for a magnetic kagome lattice. Exchange\ncoupling induces kagome-derived bands at the interface, which are protected\nfrom the bulk by the superconducting energy gap. We realize a magnetic kagome\nlattice on a superconductor by depositing Fe-porphin-chloride molecules on\nPb(111) and using temperature-activated de-chlorination and self-assembly. This\nallows us to control the formation of smaller kagome precursors and long-range\nordered kagome islands. Using scanning tunneling microscopy and spectroscopy at\n1.6 K, we identify Yu-Shiba-Rusinov states inside the superconducting energy\ngap and track their hybridization from the precursors to larger islands, where\nthe kagome lattice induces extended YSR bands. These YSR-derived kagome bands\nare protected inside the superconducting energy gap, motivating further studies\nto resolve possible spin-liquid or Kondo-lattice-type behavior."
    },
    {
        "anchor": "Stroboscopic model of transport through a quantum dot with spin-orbit\n  scattering: We present an open version of the symplectic kicked rotator as a stroboscopic\nmodel of electrical conduction through an open ballistic quantum dot with\nspin-orbit scattering. We demonstrate numerically and analytically that the\nmodel reproduces the universal weak localization and weak anti-localization\npeak in the magnetoconductance, as predicted by random-matrix theory (RMT). We\nalso study the transition from weak localization to weak anti-localization with\nincreasing strength of the spin-orbit scattering, and find agreement with RMT.",
        "positive": "Magnetic Flux Periodicity in Second Order Topological Superconductors: The magnetic flux periodicity of $\\frac{hc}{2e}$ is a well known\nmanifestation of Cooper pairing in typical s-wave superconductors. In this\npaper we theoretically show that the flux periodicity of a two-dimensional\nsecond-order topological superconductor, which features zero-energy Majorana\nmodes localized at the corners of the sample, is $\\frac{hc}{e}$ instead. We\nfurther show that the periodicity changes back to $\\frac{hc}{2e}$ at the\ntransition to a topologically trivial superconductor, where the Majorana modes\nhybridize with the bulk states, demonstrating that the doubling of periodicity\nis a manifestation of the non-trivial topology of the state."
    },
    {
        "anchor": "Symmetry breaking in Laughlin's state on a cylinder: We investigate Laughlin's fractional quantum Hall effect wave function on a\ncylinder. We show that it displays translational symmetry breaking in the axial\ndirection for sufficiently thin cylinders. At filling factor 1/p, the period is\np times the period of the filled lowest Landau level. The proof uses a\nconnection with one-dimensional polymer systems and discrete renewal equations.",
        "positive": "Influence of non-equilibrium phonons on the spin dynamics of a single Cr\n  atom: We analyse the influence of optically generated non-equilibrium phonons on\nthe spin relaxation and effective spin temperature of an individual Cr atom\ninserted in a quantum dot. Using a three pulses pump-probe technique, we show\nthat the spin relaxation measured in resonant optical pumping experiments\nstrongly depends on the optical excitation conditions. We observe for an\nisolated Cr in the dark a heating time shorter than a few hundreds $ns$ after\nan initial high power non-resonant excitation pulse. A cooling time larger than\na few tens of $\\mu s$, independent on the excitation, is obtained in the same\nexperimental conditions. We show that a tunable spin-lattice coupling dependent\non the density of non-equilibrium phonons can explain the observed dynamics.\nLow energy excitation conditions are found where the Cr spin states\nS$_z$=$\\pm$1 can be efficiently populated by a non-resonant optical excitation,\nprepared and read-out by resonant optical pumping and conserved in the dark\nduring a few $\\mu$s."
    },
    {
        "anchor": "Single Spin Transport Spectroscopy - Current Blockade and Spin Decay: We present a theory of a single-electron transistor exchange-coupled to a\nlocalized spin. We show how to gain detailed quantitative knowledge about the\nattached spin such as spin size, exchange coupling strength, Land\\'e g-factor,\nand spin decay time $T_1$ by utilizing a robust blockade phenomenon of DC\nmagnetotransport with accompanying noise enhancement. Our studies are of\nparticular relevance to spin-resolved scanning single-electron transistor\nmicroscopy, electronic transport through nanomagnets, and the effect of\nhyperfine interaction on transport electrons by surrounding nuclear spins.",
        "positive": "Klein tunneling of Weyl magnons: Similar to Weyl semimetals, in magnetic materials, magnon bands can host Weyl\npoints, around which the bosonic excitations are called Weyl magnons. Here, we\ninvestigate the Klein tunneling of Weyl magnons, during the process of which\nWeyl magnons tunnel through a high potential barrier. Specifically, we study\nthe magnetization current carried by Weyl magnons in a quasi-one-dimensional\nmagnetic wire, in the middle of which a gate magnetic field is applied to\ngenerate a potential barrier. The transmission probability is calculated and\nthe Landauer-B\\\"uttiker formalism is used to find the magnetization current.\nVarious types of Weyl magnons are considered, including isotropic, tilted, and\ndouble Weyl magnons. Unlike in Weyl semimetals where fermionic statistics is in\ncharge and the current oscillates with the gate field as a result of\nFabry-P\\'erot resonances, here Bose distribution smears out the oscillations.\nWe find that the tilting of the Weyl cone causes the decrease of the\nmagnetization current from Klein tunneling, while for double Weyl magnons,\nKlein tunneling is absent in the direction of quadratic dispersion, but is\nenhanced in the direction of linear dispersion. Our results show that the\nbehaviour of the current-voltage characteristics of magnons is rather different\nfrom that of electrons due to different statistics, although the\nsingle-particle properties, such as the transmission probabilities, are the\nsame for both Weyl bosons and Weyl fermions."
    },
    {
        "anchor": "Coherent propagation of waves in random media with weak nonlinearity: We develop a diagrammatic theory for transport of waves in disordered media\nwith weak nonlinearity. We first represent the solution of the nonlinear wave\nequation as a nonlinear Born series. From this, we construct nonlinear ladder\nand crossed diagrams for the average wave intensity. Then, we sum up the\ndiagrammatic series completely, i.e. nonperturbatively in the strength of the\nnonlinearity, and thereby obtain integral equations describing both nonlinear\ndiffusive transport and coherent backscattering of the average intensity. As\nmain result, we find that the nonlinearity significantly influences the\nmagnitude of the coherent backscattering effect. Depending on the type of\nnonlinearity, coherent backscattering is either enhanced or suppressed, as\ncompared to the linear case.",
        "positive": "Radiative coupling of A and B excitons in ZnO: Radiation-induced coupling between A and B excitons in ZnO is theoretically\nstudied. Considering the center-of-mass motion of excitons in bulk and thin\nfilm structures, we reveal the eigenmodes of an exciton--radiation coupled\nsystem and the ratio of each excitonic component, which is determined from\ndiagonalization of the self-consistent equation between the polarization and\nthe Maxwell electric field. In particular, in a nano-to-bulk crossover size\nregime, the large interaction volume between multipole-type excitonic waves and\nradiation waves causes radiative coupling between excitons from different\nvalence bands, which leads to an enhancement of the radiative correction. The\nresults presented in this study are in striking contrast with the conventional\nview of the optical response of excitons in ZnO, where A and B excitons are\nindependently assigned to their respective spectral structures. It is also\nclarified that the density of each excitonic component is of a significant\nvalue for attribution of nonlinear optical signals."
    },
    {
        "anchor": "Hole spin qubits in thin curved quantum wells: Hole spin qubits are frontrunner platforms for scalable quantum computers\nbecause of their large spin-orbit interaction which enables ultrafast\nall-electric qubit control at low power. The fastest spin qubits to date are\ndefined in long quantum dots with two tight confinement directions, when the\ndriving field is aligned to the smooth direction. However, in these systems the\nlifetime of the qubit is strongly limited by charge noise, a major issue in\nhole qubits. We propose here a different, scalable qubit design, compatible\nwith planar CMOS technology, where the hole is confined in a curved germanium\nquantum well surrounded by silicon. This design takes full advantage of the\nstrong spin-orbit interaction of holes, and at the same time suppresses charge\nnoise in a wide range of configurations, enabling highly coherent, ultrafast\nqubit gates. While here we focus on a Si/Ge/Si curved quantum well, our design\nis also applicable to different semiconductors. Strikingly, these devices allow\nfor ultrafast operations even in short quantum dots by a transversal electric\nfield. This additional driving mechanism relaxes the demanding design\nconstraints, and opens up a new way to reliably interface spin qubits in a\nsingle quantum dot to microwave photons. By considering state-of-the-art\nhigh-impedance resonators and realistic qubit designs, we estimate interaction\nstrengths of a few hundreds of MHz, largely exceeding the decay rate of spins\nand photons. Reaching such a strong coupling regime in hole spin qubits will be\na significant step towards high-fidelity entangling operations between distant\nqubits, as well as fast single-shot readout, and will pave the way towards the\nimplementation of a large-scale semiconducting quantum processor.",
        "positive": "Effect of Energy Band Gap in Graphene on Negative Refraction through the\n  Veselago Lens and Electron Conductance: A remarkable property of intrinsic graphene is that upon doping, electrons\nand holes travel through the monolayer thick material with constant velocity\nwhich does not depend on energy up to about $0.3$ eV (Dirac fermions), as\nthough the electrons and holes are massless particles and antiparticles which\nmove at the Fermi velocity $v_F$. Consequently, there is Klein tunneling at a\n$p-n$ junction, in which there is no backscattering at normal incidence of\nmassless Dirac fermions. However, this process yielding perfect transmission at\nnormal incidence is expected to be affected when the group velocity of the\ncharge carriers is energy dependent and there is non-zero effective mass for\nthe target particle. We investigate how away from normal incidence the combined\neffect of incident electron energy $\\epsilon$ and band gap parameter $\\Delta$\ncan determine whether a $p-n$ junction would allow focusing of an electron beam\nby behaving like a Veselago lens with negative refractive index. We demonstrate\nthat there is a specific region in $\\epsilon-\\Delta$ space where the index of\nrefraction is negative, i.e., where monolayer graphene behaves as a\nmetamaterial. Outside this region, the refractive index may be positive or\nthere may be no refraction at all. We compute the ballistic conductance across\na $p-n$ junction as a function of $\\Delta$ and $\\epsilon$ and compare our\nresults with those for a single electrostatic potential barrier and multiple\nbarriers."
    },
    {
        "anchor": "Gap dependent mass of photon in photonic topological insulator: By using an analogy with axionic like systems, we study light propagation in\nperiodic photonic topological insulator (PTI). The main result of this paper is\nan explicit expression for the PTI band structure. More specifically, it was\nfound that for nonzero values of the topological phase difference\n$\\gamma=\\theta_2-\\theta_1$ a finite gap $\\delta \\propto\\gamma^2$ opens in the\nspectrum which is equivalent to appearance of nonzero effective photon mass\n$m^{*}(\\delta)\\propto \\frac{\\sqrt{\\delta}}{\\delta +2}$.",
        "positive": "Floquet states and optical conductivity of an irradiated two dimensional\n  topological insulator: We study the topology of the Floquet states and time-averaged optical\nconductivity of the lattice model of a thin topological insulator subject to a\ncircularly polarized light using the extended Kubo formalism. Two driving\nregimes, the off-resonant and on-resonant, and two models for the occupation of\nthe Floquet states, the ideal and mean-energy occupation, are considered. In\nthe ideal occupation, the real part of DC optical Hall conductivity is shown to\nbe quantized while it is not quantized for the mean energy distribution. The\noptical transitions in the Floquet band structure depend strongly on the\noccupation and also the optical weight which consequently affect all components\nof optical conductivity. At high frequency regime, we present an analytical\ncalculation of the effective Hamiltonian and also its phase diagram which\ndepends on the tunneling energy between two surfaces. The topology of the\nsystem shows rich phases when it is irradiated by a weak on-resonant drive\ngiving rise to emergence of anomalous edge states."
    },
    {
        "anchor": "Quasi-flat plasmonic bands in twisted bilayer graphene: The charge susceptibility of twisted bilayer graphene is investigated in the\nDirac cone, respectively random-phase approximation. For small enough twist\nangles $\\theta\\lesssim 2^\\circ$ we find weakly Landau damped interband\nplasmons, i.~e., collective excitonic modes which exist in the undoped\nmaterial, with an almost constant energy dispersion. In this regime, the loss\nfunction can be described as a Fano resonance and we argue that these\nexcitations arise from the interaction of quasi-localised states with the\nincident light field. These predictions can be tested by nano-infrared imaging\nand possible applications include a \"perfect\" lens without the need of\nleft-handed materials.",
        "positive": "Strain effects in phosphorous bound exciton transitions in silicon: Donor spin states in silicon are a promising candidate for quantum\ninformation processing. One possible donor spin readout mechanism is the bound\nexciton transition that can be excited optically and creates an electrical\nsignal when it decays. This transition has been extensively studied in bulk,\nbut in order to scale towards localized spin readout, microfabricated\nstructures are needed for detection. As these electrodes will inevitably cause\nstrain in the silicon lattice, it will be crucial to understand how strain\naffects the exciton transitions. Here we study the phosphorous donor bound\nexciton transitions in silicon using hybrid electro-optical readout with\nmicrofabricated electrodes. We observe a significant zero-field splitting as\nwell mixing of the hole states due to strain. We can model these effects\nassuming the known asymmetry of the hole g-factors and the Pikus-Bir\nHamiltonian describing the strain. In addition, we describe the temperature,\nlaser power and light polarization dependence of the transitions. Importantly,\nthe hole-mixing should not prevent donor electron spin readout and using our\nmeasured parameters and numerical simulations we anticipate that hybrid spin\nreadout in a silicon-on-insulator platform should be possible, allowing\nintegration to silicon photonics platforms."
    },
    {
        "anchor": "$\u03c3_h$ symmetry and electron-phonon interaction in two-dimensional\n  crystalline systems: The coupling of electrons and phonons is governed wisely by the symmetry\nproperties of the crystal structures. In particular, for two-dimensional (2D)\nsystems, it has been suggested that the electrons do not couple to phonons with\npure out-of-plane distortion, as long as there is a $\\sigma_h$ symmetry. We\nshow that such a statement is correct when constituents of the unit-cell layer\nare only located in the $\\sigma_h$ symmetric plane; a prominent example of such\na system is graphene. For those 2D crystals in which atoms are vertically\nlocated away from the horizontal symmetric plane (e.g., 1H transition metal\ndichalcogenides), acoustic flexural modes do not couple to the electrons up to\nlinear order, while optical flexural phonons, which preserve $\\sigma_h$\nsymmetry, do couple with the electrons. Our conclusions are supported by an\nanalytic argument together with numerical calculations using density functional\nperturbation theory.",
        "positive": "Inverse Orbital Hall Effect Discovered from Light-Induced Terahertz\n  Emission: Recent progress in orbitronics reveals the possibility of using orbit current\nas an information carrier. The interconversion between orbit currents and\ncharge currents is crucial for orbit information processing. Although orbit\ncurrents can be created from charge currents via the orbital Hall effect, the\nconversion from orbit currents into charge currents has been observed only in\nvery few systems due to the lack of a reliable orbit current source and the\ndisturbance of the omnipresent inverse spin Hall effect. In this study, we show\nthat ultrafast pulses of orbit current can be generated in Ni layers by\nfemtosecond laser pulses. We demonstrate that, by injecting such orbit current\npulses into nonmagnetic metals, a transient charge current is induced and emits\nterahertz electromagnetic pulses. The nonmagnetic metal layer acts as a\nconverter of the orbit current into the charge current. The discovery of the\ngeneration and conversion of light-induced orbit current opens a new route for\ndeveloping future orbitronic devices."
    },
    {
        "anchor": "Spin field-effect transistor in a quantum spin-Hall device: We discuss the transport properties of a quantum spin-Hall insulator with\nsizable Rashba spin-orbit coupling in a disk geometry. The presence of\ntopologically protected helical edge states allows for the control and\nmanipulation of spin polarized currents: when ferromagnetic leads are coupled\nto the quantum spin-Hall device, the ballistic conductance is modulated by the\nRashba strength. Therefore, by tuning the Rashba interaction via an\nall-electric gating, it is possible to control the spin polarization of\ninjected electrons.",
        "positive": "Ab-intio study of ultrafast charge dynamics in graphene: Monolayer graphene provides an ideal material to explore one of the\nfundamental light-field driven interference effects: Landau-Zener-St\\\"uckelberg\ninterference. However, direct observation of the resulting interference\npatterns in momentum space has not proven possible, with\nLandau-Zener-St\\\"uckelberg interference observed only indirectly through\noptically induced residual currents. Here we show that the transient electron\nmomentum density (EMD), an object that can easily be obtained in experiment,\nprovides an excellent description of momentum resolved charge excitation. We\nemploy state-of-the-art time-dependent density function theory calculations,\ndemonstrating by direct comparison of EMD with conduction band occupancy,\nobtained from projecting the time propagated wavefunction onto the ground\nstate, that the two quantities are in excellent agreement. For even the most\nintense laser pulses we find that the electron dynamics to be almost completely\ndominated by the $\\pi$-band, with transitions to other bands strongly\nsuppressed. Simple model based tight-binding approaches can thus be expected to\nprovide an excellent description for the laser induced electron dynamics in\ngraphene."
    },
    {
        "anchor": "Creating One-dimensional Nanoscale Periodic Ripples in a Continuous\n  Mosaic Graphene Monolayer: In previous studies, it proved difficult to realize periodic graphene ripples\nwith wavelengths of few nanometers. Here we show that one-dimensional periodic\ngraphene ripples with wavelengths from 2 nm to tens of nanometers can be\nimplemented in the intrinsic areas of a continuous mosaic, locally N-doped,\ngraphene monolayer by simultaneously using both the thermal strain engineering\nand the anisotropic surface stress of Cu substrate. Our result indicates that\nthe constraint imposed at the boundaries between the intrinsic and the N-doped\nregions play a vital role in creating these 1D ripples. We also demonstrate\nthat the observed rippling modes are beyond the descriptions of continuum\nmechanics due to the decoupling of graphene bending and tensional deformations.\nScanning tunneling spectroscopy measurements indicate that the nanorippling\ngenerates a periodic electronic superlattice and opens a zero-energy gap of\nabout 130 meV in graphene. This result may pave a facile way for tailoring the\nstructures and electronic properties of graphene.",
        "positive": "A Description of Kitaev's Honeycomb Model with Toric-Code Stabilizers: We present a solution of Kitaev's spin model on the honeycomb lattice and of\nrelated topologically ordered spin models. We employ a Jordan-Wigner type\nfermionization and find that the Hamiltonian takes a BCS type form, allowing\nthe system to be solved by Bogoliubov transformation. Our fermionization does\nnot employ non-physical auxiliary degrees of freedom and the eigenstates we\nobtain are completely explicit in terms of the spin variables. The ground-state\nis obtained as a BCS condensate of fermion pairs over a vacuum state which\ncorresponds to the toric code state with the same vorticity. We show in detail\nhow to calculate all eigenstates and eigenvalues of the model on the torus. In\nparticular, we find that the topological degeneracy on the torus descends\ndirectly from that of the toric code, which now supplies four vacua for the\nfermions, one for each choice of periodic vs. anti-periodic boundary\nconditions. The reduction of the degeneracy in the non-Abelian phase of the\nmodel is seen to be due to the vanishing of one of the corresponding candidate\nBCS ground-states in that phase. This occurs in particular in the fully\nperiodic vortex-free sector. The true ground-state in this sector is exhibited\nand shown to be gapped away from the three partially anti-periodic\nground-states whenever the non-Abelian phase is gapped."
    },
    {
        "anchor": "Synthesis and Magnetic Properties of Ferroelectric GdCrO3 nanoparticles: Homogeneous single phase GdCrO3 nanoparticles are synthesized by a\nmodified-hydrothermal synthesis. The sample shows a compensation temperature at\n128 K, below which the DC magnetization becomes negative and positive at low\ntemperatures due to the competition between the two sublattice magnetization.\nAt N\\'eel temperature (168K), the line width and the intensity show an abrupt\ntransition, revealed from electron paramagnetic resonance spectroscopy.",
        "positive": "Magnetostatic interaction between Bloch Point nanospheres: Three-dimensional topological textures have become a topic of intense\ninterest in recent years. Through analytical calculations, this work determines\nthe magnetostatic field produced by a Bloch Point (BP) singularity confined in\na magnetic nanosphere. It is observed that BPs hosted in a nanosphere generate\nmagnetic fields with quadrupolar nature. This finding is interesting because it\nshows the possibility of obtaining quadrupole magnetic fields with just one\nmagnetic particle, unlike other propositions considering arrays of magnetic\nelements to generate this kind of field. The obtained magnetostatic field\nallows us to determine the interaction between two BPs as a function of the\nrelative orientation of their polarities and the distance between them. It is\nshown that depending on the rotation of one BP related to the other, the\nmagnetostatic interaction varies in strength and character, being attractive or\nrepulsive. The obtained results reveal that the BP interaction has a complex\nbehavior beyond topological charge-mediated interaction."
    },
    {
        "anchor": "Topological superconductivity in tripartite\n  superconductor-ferromagnet-semiconductor nanowires: Motivated by recent experiments searching for Majorana zero modes in\ntripartite semiconductor nanowires with epitaxial superconductor and\nferromagnetic-insulator layers, we explore the emergence of topological\nsuperconductivity in such devices for paradigmatic arrangements of the three\nconstituents. Accounting for the competition between magnetism and\nsuperconductivity, we treat superconductivity self consistently and describe\nthe electronic properties, including the superconducting and ferromagnetic\nproximity effects, within a direct wave-function approach. We conclude that the\nmost viable mechanism for topological superconductivity relies on a\nsuperconductor-semiconductor-ferromagnet arrangement of the constituents, in\nwhich spin splitting and superconductivity are independently induced in the\nsemiconductor by proximity and superconductivity is only weakly affected by the\nferromagnetic insulator.",
        "positive": "Effects of biaxial strain on the electronic structures and band\n  topologies of group-V elemental monolayers: Using first-principles calculations, we systematically investigate the\nelectronic structures and band topologies of four kinds of group-V elemental\n(P, As, Sb and Bi) monolayers with buckled honeycomb structure. It is found\nthat all these monolayers can change from semiconducting to semimetallic under\ncompressive strain. If a tensile strain is however applied, the P, As and Sb\nmonolayers undergo phase transition from topologically trivial to non-trivial\nregime, whereas the topological insulating nature of Bi monolayer remains\nunchanged. With tunability of the band gaps and band topologies, it can be\nexpected that these elemental monolayers could be promising candidates for\nfuture optoelectronic and spintronic applications."
    },
    {
        "anchor": "Dynamic thermal relaxation in metallic films at sub-kelvin temperatures: The performance of low temperature detectors utilizing thermal effects is\ndetermined by their energy relaxation properties. Usually, heat transport\nexperiments in mesoscopic structures are carried out in the steady-state, where\ntemperature gradients do not change in time. Here, we present an experimental\nstudy of dynamic thermal relaxation in a mesoscopic system -- thin metallic\nfilm. We find that the thermal relaxation of hot electrons in copper and silver\nfilms is characterized by several time constants, and that the annealing of the\nfilms changes them. In most cases, two time constants are observed, and we can\nmodel the system by introducing an additional thermal reservoir coupled to the\nfilm electrons. We determine the specific heat of this reservoir and its\ncoupling to the electrons. The experiments point at the importance of grain\nstructure on the thermal relaxation of electrons in metallic films.",
        "positive": "Strain engineered graphene using a nanostructured substrate: II\n  Pseudo-magnetic fields: The strain induced pseudo-magnetic field in supported graphene deposited on\ntop of a nanostructured substrate is investigated by using atomistic\nsimulations. Step, elongated trench, one dimensional barrier, spherical\nbubbles, Gaussian bump and Gaussian depression are considered as support\nstructures for graphene. From the obtained optimum configurations we found very\nstrong induced pseudo-magnetic fields which can reach up to $\\sim$ 1000\\,T due\nto the strain-induced deformations in the supported graphene. Different\nmagnetic confinements with controllable geometries are found by tuning the\npattern of the substrate. The resulting induced magnetic fields for graphene on\ntop of a step, barrier and trench are calculated. In contrast to the step and\ntrench the middle part of graphene on top of a barrier has zero pseudo-magnetic\nfield. This study provides a theoretical background for designing magnetic\nstructures in graphene by nanostructuring substrates. We found that altering\nthe radial symmetry of the deformation, changes the six-fold symmetry of the\ninduced pseudo-magnetic field."
    },
    {
        "anchor": "Orbital Torque: Torque Generation by Orbital Current Injection: We propose a mechanism of torque generation by injection of an orbital\ncurrent, which we call $\\textit{orbital torque}$. In a magnetic bilayer\nconsisting of a nonmagnet (NM) and a ferromagnet (FM), we consider a situation\nwhere the spin-orbit coupling (SOC) is present only in the FM. Although the SOC\nis absent in the NM, the orbital Hall effect can arise in the NM. When the\nresulting orbital Hall current is injected to the FM, the SOC of the FM\nconverts the orbital angular momentum into spin, which exerts torque to the\nmagnetization of the FM. Remarkably, even for small SOC strength comparable to\nthat of $3d$ FMs, the orbital torque can be comparable to the spin torque\ninduced by the spin Hall effect of the NM with strong SOC. This provides a way\nto experimentally probe the OHE and opens a new venue to achieving spin-torque\ndevices based on light elements that exhibit gigantic orbital response.\nExperimental implications are discussed.",
        "positive": "Quantum transport in a resonant tunnel junction coupled to a\n  nanomechanical oscillator: We discuss the quantum transport of electrons through a resonant tunnel\njunction coupled to a nanomechanical oscillator at zero temperature. By using\nthe Green's function technique we calculate the transport properties of\nelectrons through a single dot strongly coupled to a single oscillator. We\nconsider a finite chemical potential difference between the right and left\nleads. In addition to the main resonant peak of electrons on the dot, we find\nsatellite peaks due to the creation of phonons. These satellite peaks become\nsharper and more significant with increasing coupling strength between the\nelectrons and the oscillator. We also consider the energy transferred from the\nelectrons to the oscillator."
    },
    {
        "anchor": "Aging effects in critical behavior of Heisenberg anisotropic ultrathin\n  films: The nonequilibrium behavior of ultrathin multilayer structures Pt/Co/Cu/Co/Pt\nand Co/Cu/Co was studied by the Monte Carlo method for different types of\nmagnetic anisotropy. The results of the calculated two-time autocorrelation\nfunction were pulled from. In the course of the study, the evolution from the\nstructures of their varied original states was considered. An analysis of the\nobtained results clearly indicates the occurrence of aging effects, which\nmanifest themselves in slowing down the correlation processes when the waiting\ntime increases. The results of the dependence of the magnetic characteristics\nof the studied systems on the film thicknesses are obtained. There are\ndifferences between the behavior of bulk systems and multilayer structures when\naging effects are considered. In multilayer structures, the manifestation of\naging effects occurs in a wide range of temperatures $T \\leq T_c$, that is, not\nonly at the critical temperature $T_c$. When studying the transport properties\nof such systems, one can reveal the influence of anisotropy and initial states\non the values of the two-time dependence of the magnetoresistance. When\nstudying the transport properties of such systems, one can reveal the influence\nof anisotropy and initial states on the values of the two-time dependence of\nthe magnetoresistance and the occurrence of aging effects.",
        "positive": "Composite boson many-body theory for Frenkel excitons: We present a many-body theory for Frenkel excitons which takes into account\ntheir composite nature exactly. Our approach is based on four commutators\nsimilar to the ones we previously proposed for Wannier excitons. They allow us\nto calculate any physical quantity dealing with $N$ excitons in terms of \"Pauli\nscatterings\" for carrier exchange in the absence of carrier interaction and\n\"interaction scatterings\" for carrier interaction in the absence of carrier\nexchange. We show that Frenkel excitons have a novel \"transfer assisted\nexchange scattering\", specific to these excitons. It comes from indirect\nCoulomb processes between localized atomic states. These indirect processes,\ncommonly called \"electron-hole exchange\" in the case of Wannier excitons and\nmost often neglected, are crucial for Frenkel excitons, as they are the only\nones responsible for the excitation transfer. We also show that in spite of the\nfact that Frenkel excitons are made of electrons and holes on the same atomic\nsite, so that we could naively see them as elementary particles, they\ndefinitely are composite objects, their composite nature appearing through\nvarious properties, not always easy to guess. The present many-body theory for\nFrenkel excitons is thus going to appear as highly valuable to securely tackle\ntheir many-body physics, as in the case of nonlinear optical effects in organic\nsemiconductors."
    },
    {
        "anchor": "$s$-$d$ model for local and nonlocal spin dynamics in laser-excited\n  magnetic heterostructures: We discuss a joint microscopic theory for the laser-induced magnetization\ndynamics and spin transport in magnetic heterostructures based on the $s$-$d$\ninteraction. Angular momentum transfer is mediated by scattering of itinerant\n$s$ electrons with the localized ($d$ electron) spins. We use the corresponding\nrate equations and focus on a spin one-half $d$ electron system, leading to a\nsimplified analytical expression for the dynamics of the local magnetization\nthat is coupled to an equation for the non-equilibrium spin accumulation of the\n$s$ electrons. We show that this description converges to the microscopic\nthree-temperature model in the limit of a strong $s$-$d$ coupling. The equation\nfor the spin accumulation is used to introduce diffusive spin transport. The\npresented numerical solutions show that during the laser-induced\ndemagnetization in a ferromagnetic metal a short-lived spin accumulation is\ncreated that counteracts the demagnetization process. Moreover, the spin\naccumulation leads to the generation of a spin current at the interface of a\nferromagnetic and non-magnetic metal. Depending on the specific magnetic\nsystem, both local spin dissipation and interfacial spin transport are able to\nenhance the demagnetization rate by providing relaxation channels for the spin\naccumulation that is build up during demagnetization in the ferromagnetic\nmaterial.",
        "positive": "Beat Phenomena in Metal Nanowires, and their Implications for\n  Resonance-Based Elastic Property Measurements: The elastic properties of 1D nanostructures such as nanowires are often\nmeasured experimentally through actuation of the nanowire at its resonance\nfrequency, and then relating the resonance frequency to the elastic stiffness\nusing elementary beam theory. In the present work, we utilize large scale\nmolecular dynamics simulations to report a novel beat phenomenon in [110]\noriented Ag nanowires. The beat phenomenon is found to arise from the asymmetry\nof the lattice spacing in the orthogonal elementary directions of the [110]\nnanowire,i.e., [-110] and [001] directions, which results in two different\nprincipal moments of inertia. Because of this, actuations imposed along any\nother direction are found to decompose into two orthogonal vibrational\ncomponents based on the actuation angle relative to these two elementary\ndirections, with this phenomenon being generalizable to <110> FCC nanowires of\ndifferent materials (Cu, Au, Ni, Pd and Pt).The beat phenomenon is explained\nusing a discrete moment of inertia model based on the hard sphere assumption,\nthe model is utilized to show that surface effects enhance the beat phenomenon,\nwhile the effect is reduced with increasing nanowires cross-sectional size or\naspect ratio.Most importantly, due to the existence of the beat phenomena, we\ndemonstrate that in resonance experiments only a single frequency component is\nexpected to be observed, particularly when the damping ratio is relatively\nlarge or very small.Furthermore, for a large range of actuation angles, the\nlower frequency is more likely to be detected than the higher one,which implies\nthe experimental predictions of Young's modulus obtained from resonance may in\nfact be under predictions. The present study therefore has significant\nimplications for experimental interpretations of Young's modulus as obtained\nvia resonance testing."
    },
    {
        "anchor": "Energy spectrum of semimetallic HgTe quantum wells: Quantum wells (QWs) based on mercury telluride (HgTe) thin films provide a\nlarge scale of unusual physical properties starting from an insulator via a\ntwo-dimensional Dirac semimetal to a three-dimensional topological insulator.\nThese properties result from the dramatic change of the QW band structure with\nthe HgTe film thickness. Although being a key property, these energy dispersion\nrelations cannot be reflected in experiments due to the lack of appropriate\ntools. Here we report an experimental and theoretical study of two HgTe quantum\nwells with inverted energy spectrum in which two-dimensional semimetallic\nstates are realized. Using magneto-optical spectroscopy at sub-THz frequencies\nwe were able to obtain information about electron and hole cyclotron masses at\nall relevant Fermi level positions and different charge densities. The outcome\nis also supported by a Shubnikov-de Haas analysis of capacitance measurements,\nwhich allows obtaining information about the degeneracy of the active modes.\nFrom these data, it is possible to reconstruct electron and hole dispersion\nrelations. Detailed comparative analysis of the energy dispersion relations\nwith theoretical calculations demonstrates a good agreement, reflecting even\nseveral subtle features like band splitting, the second conduction band, and\nthe overlaps between the first conduction and first valence band. Our study\ndemonstrates that the cyclotron resonance experiments can be efficiently used\nto directly obtain the band structures of semimetallic 2D materials.",
        "positive": "Probing Robust Majorana Signatures by Crossed Andreev Reflection with a\n  Quantum Dot: We propose a three-terminal structure to probe robust signatures of Majorana\nzero modes. This structure consists of a quantum dot coupled to the normal\nmetal, s-wave superconducting and Majorana Y-junction leads. The zero-bias\ndifferential conductance at zero temperature of the normal-metal lead peaks at\n$2e^{2}/h$, which will be deflected after Majorana braiding. This quantized\nconductance can entirely arise from the Majorana-induced crossed Andreev\nreflection, protected by the energy gap of the superconducting lead. We find\nthat the effect of thermal broadening is significantly suppressed when the dot\nis on resonance. In the case that the energy level of the quantum dot is much\nlarger than the superconducting gap, tunneling processes are dominated by\nMajorana-induced crossed Andreev reflection. Particularly, a novel kind of\ncrossed Andreev reflection equivalent to the splitting of charge quanta $3e$\noccurs after Majorana braiding."
    },
    {
        "anchor": "Bulk Pumping in 2D Topological Phases: The notion of topological (Thouless) pumping in topological phases is\ntraditionally associated with Laughlin's pump argument for the quantization of\nthe Hall conductance in two-dimensional (2D) quantum Hall systems. It relies on\nmagnetic flux variations that thread the system of interest without penetrating\nits bulk, in the spirit of Aharonov-Bohm effects. Here we explore a different\nparadigm for topological pumping induced, instead, by magnetic flux variations\n$\\delta\\chi$ inserted through the bulk of topological phases. We show that\n$\\delta\\chi$ generically controls the analog of a topological pump, accompanied\nby robust physical phenomena. We demonstrate this concept of bulk pumping in\ntwo paradigmatic types of 2D topological phases: integer and fractional quantum\nHall systems and topological superconductors. We show, in particular, that bulk\npumping provides a unifying connection between seemingly distinct physical\neffects such as density variations described by Streda's formula in quantum\nHall phases, and fractional Josephson currents in topological superconductors.\nWe discuss the generalization of bulk pumping to other types of topological\nphases.",
        "positive": "SQUIPT - Superconducting Quantum Interference Proximity Transistor: We present the realization and characterization of a novel-concept\ninterferometer, the superconducting quantum interference proximity transistor\n(SQUIPT). Its operation relies on the modulation with the magnetic field of the\ndensity of states of a proximized metallic wire embedded in a superconducting\nring. Flux sensitivities down to $\\sim 10^{-5} \\Phi_0$Hz$^{-1/2}$ can be\nachieved even for a non-optimized design, with an intrinsic dissipation ($\\sim\n100$ fW) which is several orders of magnitude smaller than in conventional\nsuperconducting interferometers. Our results are in agreement with the\ntheoretical prediction of the SQUIPT behavior, and suggest that optimization of\nthe device parameters would lead to a large enhancement of sensitivity for the\ndetection of tiny magnetic fields. The features of this setup and their\npotential relevance for applications are further discussed."
    },
    {
        "anchor": "Coulomb blockade in quantum dots under AC pumping: We study conductance through a quantum dot under Coulomb blockade conditions\nin the presence of an external periodic perturbation. The stationary state is\ndetermined by the balance between the heating of the dot electrons by the\nperturbation and cooling. We analyze two cooling mechanisms: electron exchange\nwith the cold contacts and emission of phonons. Together with the usual linear\nOhmic heating of the dot electrons we consider possible effects of dynamic\nlocalization. The combination of the abovementioned factors may result in a\ndrastic change of the shape of the Coulomb blockade peak with respect to the\nusual equilibrium one.",
        "positive": "A controllable valley polarization in Graphene: The electron transport of different conical valleys is investigated in\ngraphene with extended line-defects. Intriguingly, the electron with a definite\nincident angle can be completely modulated into one conical valley by a\nresonator which consists of several paralleling line-defects. The related\nincident angle can be controlled easily by tuning the parameters of the\nresonator. Therefore, a controllable 100% valley polarization, as well as the\ndetection of the valley polarization, can be realized conveniently by tuning\nthe number of line-defects and the distance between two nearest neighbouring\nline-defects. This fascinating finding opens a way to realize the valley\npolarization by line-defects. With the advancement of experimental\ntechnologies, this resonator is promising to be realized and thus plays a key\nrole in graphene valleytronics."
    },
    {
        "anchor": "Optical Conductivity in an effective model for Graphene: Finite\n  temperature corrections: In this article, we investigate the temperature and chemical potential\ndependence of the optical conductivity of graphene, within a field theoretical\nrepresentation in the continuum approximation, arising from an underlying\ntight-binding atomistic model, that includes up to next-to-nearest neighbor\ncoupling. Our calculations allow us to obtain the dependence of the optical\nconductivity on frequency, temperature and finite chemical potential,\ngeneralizing our previously reported calculations at zero temperature, and\nreproducing the universal and experimentally verified value at zero frequency.",
        "positive": "Non-equilibrium current and relaxation dynamics of a charge-fluctuating\n  quantum dot: We study the steady-state current in a minimal model for a quantum dot\ndominated by charge fluctuations and analytically describe the time evolution\ninto this state. The current is driven by a finite bias voltage V across the\ndot, and two different renormalization group methods are used to treat small to\nintermediate local Coulomb interactions. The corresponding flow equations can\nbe solved analytically which allows to identify all microscopic cutoff scales.\nExploring the entire parameter space we find rich non-equilibrium physics which\ncannot be understood by simply considering the bias voltage as an infrared\ncutoff. For the experimentally relevant case of left-right asymmetric\ncouplings, the current generically shows a power-law suppression for large V.\nThe relaxation dynamics towards the steady state features characteristic\noscillations as well as an interplay of exponential and power-law decay."
    },
    {
        "anchor": "Work and heat for two-level systems in dissipative environments: Strong\n  driving and non-Markovian dynamics: Work, moments of work and heat flux are studied for the generic case of a\nstrongly driven twolevel system immersed in a bosonic heat bath in domains of\nparameter space where perturbative treatments fail. This includes particularly\nthe interplay between non-Markovian dynamics and moderate to strong external\ndriving. Exact data are compared with predictions from weak coupling\napproaches. Further, the role of system-bath correlations in the initial\nthermal state and their impact on the heat flux are addressed. The relevance of\nthese results for current experimental activities on solid state devices is\ndiscussed.",
        "positive": "Manipulating Andreev and Majorana Bound States with microwaves: We study the interplay between Andreev (Majorana) bound states that form at\nthe boundary of a (topological) superconductor and a train of microwave pulses.\nWe find that the extra dynamical phase coming from the pulses can shift the\nphase of the Andreev reflection, resulting in the appear- ance of dynamical\nAndreev states. As an application we study the presence of the zero bias peak\nin the differential conductance of a normal-topological superconductor junction\n- the simplest, yet somehow ambiguous, experimental signature for Majorana\nstates. Adding microwave radiation to the measuring electrodes provides an\nunambiguous probe of the Andreev nature of the zero bias peak."
    },
    {
        "anchor": "Coherent field emission image of graphene predicted with a microscopic\n  theory: Electrons in the mono-layer atomic sheet of graphene have a long coherence\nlength of the order of micrometers. We will show that this coherence is\ntransmitted into the vacuum via electric field assisted electron emission from\nthe graphene edge. The emission current density is given analytically. The\nparity of the carbon pi-electrons leads to an image whose center is dark as a\nresult of interference. A dragonfly pattern with a dark body perpendicular to\nthe edge is predicted for the armchair edge whose emission current density is\nvanishing with the mixing angle of the pseudo-spin. The interference pattern\nmay be observed up to temperatures of thousand Kelvin as evidence of coherent\nfield emission. Moreover, this phenomenon leads to a novel coherent electron\nline source that can produce interference patterns of extended objects with\nlinear sizes comparable to the length of the graphene edge.",
        "positive": "Origami-based tunable truss structures for non-volatile mechanical\n  memory operation: Origami has recently received significant interest from the scientific\ncommunity as a building block for constructing metamaterials. However, the\nprimary focus has been placed on their kinematic applications, such as\ndeployable space structures and sandwich core materials, by leveraging the\ncompactness and auxeticity of planar origami platforms. Here, we present\nvolumetric origami cells -- specifically triangulated cylindrical origami (TCO)\n-- with tunable stability and stiffness, and demonstrate their feasibility as\nnon-volatile mechanical memory storage devices. We show that a pair of origami\ncells can develop a double-well potential to store bit information without the\nneed of residual forces. What makes this origami-based approach more appealing\nis the realization of two-bit mechanical memory, in which two pairs of TCO\ncells are interconnected and one pair acts as a control for the other pair.\nUsing TCO-based truss structures, we present an experimental demonstration of\npurely mechanical one- and two-bit memory storage mechanisms."
    },
    {
        "anchor": "Multiple transitions of the spin configuration in quantum dots: Single electron tunneling is studied in a many electron quantum dot in high\nmagnetic fields. For such a system multiple transitions of the spin\nconfiguration are theoretically predicted. With a combination of spin blockade\nand Kondo effect we are able to detect five regions with different spin\nconfigurations. Transitions are induced with changing electron numbers.",
        "positive": "Hartree simulations of coupled quantum Hall edge states in\n  corner-overgrown heterostructures: The electronic states in a corner-overgrown bent GaAs/AlGaAs quantum well\nheterostructure are studied with numerical Hartree simulations. Transmission\nelectron microscope pictures of the junction justify the sharp-corner\nassumption. In a tilted magnetic field both facets of the bent quantum well are\nbrought to a quantum Hall (QH) state, and the corner hosts an unconventional\nhybrid system of two coupled counter-propagating quantum Hall edges and an\nadditional one-dimensional accumulation wire. A subsystems model is introduced,\nwhereby the total hybrid dispersion and wavefunctions are explained in terms of\nthe constituent QH edge- and accumulation wire-subsystem dispersions and\nwavefunctions. At low magnetic fields, orthonormal basis wavefunctions of the\nhybrid system can be accurately estimated by projecting out the lowest bound\nstate of the accumulation wire from the edge state wavefunctions. At high\nmagnetic fields, the coupling between the three subsystems increases as a\nfunction of the applied magnetic field, in contrast to coplanar\nbarrier-junctions of QH systems, leading to large anticrossing gaps between the\nsubsystem dispersions. These results are discussed in terms of previously\nreported experimental data on bent quantum Hall systems."
    },
    {
        "anchor": "Photoinduced electric currents in Bose-Einstein condensates: We calculate a light-induced electric current which can occur from a\nBose-Einstein condensate under the action of an external electromagnetic field\nwith the frequency exceeding the ionization potential of the bosons, taking a\nsystem of indirect excitons as a testbed. We show that the ionization can be\naccompanied by the excitation of collective Bogoliubov modes. As a result, the\ncurrent consists of two principal components: one regular, which has a\ncounterpart in bosonic systems in the normal phase, and the other one specific\nfor condensates since the photoabsorption is mediated by the emission of\nBogoliubov quasiparticles. Surprisingly, the latter component soon becomes\npredominant with the increase of light frequency above the ionization\npotential.",
        "positive": "Interplay between the mesoscopic Stoner and Kondo effects in quantum\n  dots: We consider electrons confined to a quantum dot interacting\nantiferromagnetically with a spin-$\\half$ Kondo impurity. The electrons also\ninteract among themselves ferromagnetically with a dimensionless coupling\n$\\tilde{J}$, where $\\tilde{J}=1$ denotes the bulk Stoner transition. We show\nthat as $\\tilde{J}$ approaches 1 there is a regime with enhanced Kondo\ncorrelations, followed by one where the Kondo effect is destroyed and impurity\nis spin polarized opposite to the dot electrons. The most striking signature of\nthe first, Stoner-enhanced Kondo regime, is that a Zeeman field increases the\nKondo scale, in contrast to the case for noninteracting dot electrons.\nImplications for experiments are discussed."
    },
    {
        "anchor": "Spin-flip Raman scattering of the $\u0393$-X mixed exciton in indirect\n  band-gap (In,Al)As/AlAs quantum dots: The band structure of type-I (In,Al)As/AlAs quantum dots with band gap energy\nexceeding 1.63 eV is indirect in momentum space, leading to long-lived exciton\nstates with potential applications in quantum information. Optical access to\nthese excitons is provided by mixing of the $\\Gamma$- and X-conduction band\nvalleys, from which control of their spin states can be gained. This access is\nused here for studying the exciton spin-level structure by resonant spin-flip\nRaman scattering, allowing us to accurately measure the anisotropic hole and\nisotropic electron $g$ factors. The spin-flip mechanisms for the indirect\nexciton and its constituents as well as the underlying optical selection rules\nare determined. The spin-flip intensity is a reliable measure of the strength\nof $\\Gamma$-X-valley mixing, as evidenced by both experiment and theory.",
        "positive": "Phase measurement of photon-assisted tunneling through a quantum dot: Recent double-slit interference experiments have demonstrated the possibility\nof probing the phase of the complex transmission coefficient of a quantum dot\nvia the Aharonov-Bohm effect. We propose an extension of these experiments: an\nac voltage imposed on the side gate with the concomitant photonic sidebands\nleads to additional structure both in the amplitude and in the phase of the\nAharonov-Bohm signal. Observation of these effects would be a definitive proof\nof coherent absorption and reemission of photons from the ac source."
    },
    {
        "anchor": "Realizing Topological Superconductivity in Tunable Bose-Fermi Mixtures\n  with Transition Metal Dichalcogenide Heterostructures: Heterostructures of two-dimensional transition metal dichalcogenides (TMDs)\nare emerging as a promising platform for investigating exotic correlated states\nof matter. Here, we propose to engineer Bose-Fermi mixtures in these systems by\ncoupling inter-layer excitons to doped charges in a trilayer structure. Their\ninteractions are determined by the inter-layer trion, whose spin-selective\nnature allows excitons to mediate an attractive interaction between charge\ncarriers of only one spin species. Remarkably, we find that this causes the\nsystem to become unstable to topological p+ip superconductivity at low\ntemperatures. We then demonstrate a general mechanism to develop and control\nthis unconventional state by tuning the trion binding energy using a\nsolid-state Feshbach resonance.",
        "positive": "Atomic layer deposition of titanium nitride for quantum circuits: Superconducting thin films with high intrinsic kinetic inductance are of\ngreat importance for photon detectors, achieving strong coupling in hybrid\nsystems, and protected qubits. We report on the performance of titanium nitride\nresonators, patterned on thin films (9-110 nm) grown by atomic layer\ndeposition, with sheet inductances of up to 234 pH/square. For films thicker\nthan 14 nm, quality factors measured in the quantum regime range from 0.4 to\n1.0 million and are likely limited by dielectric two-level systems.\nAdditionally, we show characteristic impedances up to 28 kOhm, with no\nsignificant degradation of the internal quality factor as the impedance\nincreases. These high impedances correspond to an increased single photon\ncoupling strength of 24 times compared to a 50 Ohm resonator, transformative\nfor hybrid quantum systems and quantum sensing."
    },
    {
        "anchor": "Double Nuclear Spin Relaxation in Hybrid Quantum Hall Systems: Recent advances in quantum engineering have given us the ability to design\nhybrid systems with novel properties normally not present in the regime they\noperate in. The coupling of spin ensembles and magnons to microwave resonators\nhas for instance lead to a much richer understanding of collective effects in\nthese systems and their potential quantum applications. We can also hybridize\nelectron and nuclear spin ensembles together in the solid-state regime to\ninvestigate collective effects normally only observed in the atomic, molecular\nand optical world. Here we explore in the solid state regime the dynamics of a\ndouble domain nuclear spin ensemble coupled to the Nambu-Goldstone boson in\nGaAs semiconductors and show it exhibits both collective and individual\nrelaxation (thermalization) on very different time scales. Further the\ncollective relaxation of the nuclear spin ensemble is what one would expect\nfrom superradiant decay. This opens up the possibility for the exploration of\nnovel collective behaviour in solid state systems where the natural energies\nassociated with those spins are much less than the thermal energy.",
        "positive": "Noncommutative Geometry and Deformation Quantization in the Quantum Hall\n  Fluids with Inhomogeneous Magnetic Fields: It is well known that noncommutative geometry naturally emerges in the\nquantum Hall states due to the presence of strong and constant magnetic fields.\nHere, we discuss the underlying noncommutative geometry of quantum Hall fluids\nin which the magnetic fields are spatially inhomogenoeus. We analyze these\ncases by employing symplectic geometry and Fedosov's deformation quantization,\nwhich rely on symplectic connections and Fedosov star-product. Through this\nformalism, we unveil some new features concerning the static limit of the\nHaldane's unimodular metric and the Girvin-MacDonald-Platzman algebra of the\ndensity operators, which plays a central role in the fractional quantum Hall\neffect."
    },
    {
        "anchor": "The Cooper Pair Pump as a Quantized Current Source: A new charge quantization in a phase-polarized Cooper Pair Pump (CPP) is\nproposed, based on the topological properties of its Hamiltonian ground state\nover a three-dimensional parameter space $\\mathbb{P}$. The charge is quantized\nusing a set of path in $\\mathbb{P}$ covering the surface of a torus, and is a\nmultiple of the integer Chern index $c_1$ of this surface. This quantization is\nasymptotic but the pumped charge converges rapidly to the quantized value with\nthe increase in the path frequency. The topological nature of the current makes\nthis CPP implementation an excellent candidate for a metrological current\nstandard.",
        "positive": "Theoretical Study of Electrical Conduction Through a Molecule Connected\n  to Metallic Nanocontacts: We present a theoretical study of electron transport through a molecule\nconnected to two metallic nanocontacts. The system investigated is 1,4\nbenzene-dithiolate (BDT) chemically bonded to two Au contacts. The surface\nchemistry is modeled by representing the tips of the Au contacts as two atomic\nclusters and treating the molecule-cluster complex as a single entity in an\nextended Huckel tight binding scheme. We model the tips using several different\ncluster geometries. An ideal lead is attached to each cluster, and the lead to\nlead transmission is calculated. The role of the molecule-cluster interaction\nin transport is analyzed by using single channel leads. We then extend the\ncalculations to multi-channel leads that are a more realistic model of the\ntip's environment. Using the finite-voltage, finite temperature Landauer\nformula, we calculate the differential conductance for the different systems\nstudied. The similarities and differences between the predictions of the\npresent class of models and recent experimental work are discussed."
    },
    {
        "anchor": "Three-dimensional graphdiyne as a topological nodal-line semimetal: We study the electronic band structure of three-dimensional ABC-stacked\n(rhombohedral) graphdiyne, which is a new planar carbon allotrope recently\nfabricated. Using the first-principles calculation, we show that the system is\na nodal-line semimetal, in which the conduction band and valence band cross at\na closed ring in the momentum space. We derive the minimum tight-binding model\nand the low-energy effective Hamiltonian in a $4\\times 4$ matrix form. The\nnodal line is protected by a non-trivial winding number, and it ensures the\nexistence of the topological surface state in a finite-thickness slab. The\nFermi surface of the doped system exhibits a peculiar, self-intersecting\nhourglass structure, which is quite different from the torus or pipe shape in\nthe previously proposed nodal semimetals. Despite its simple configuration,\nthree-dimensional graphdiyne offers unique electronic properties distinct from\nany other carbon allotropes.",
        "positive": "Chiral filtering in graphene with coupled valleys: We analyze the problem of electronic transmission through different regions\nof a graphene sheet that are characterized by different types of connections\nbetween the Dirac points. These valley symmetry breaking Hamiltonians might\narise from electronic self-interaction mediated by the dielectric environment\nof distinct parts of the substrate on which the graphene sheet is placed. We\nshow that it is possible to have situations in which we can use these regions\nto select or filter states of one desired chirality."
    },
    {
        "anchor": "Role of electrical field in quantum Hall effect of graphene: The ballistic motion of carriers of graphene in an orthogonal electromagnetic\nfield is investigated to explain Hall conductance of graphene under\nexperimental conditions. With the electrical field, all electronic eigen-states\nhave the same expectation value of the velocity operator, or classically, all\ncarriers move in cycloids with the same average velocity. The magnitude of this\nvelocity is just appropriate to generate the quantized Hall conductance which\nis in turn exactly independent of the external field. Electrical field changes\neach Landau level into a bundle of energies, whose overlap in large fields\ndestroys the quantized Hall conductance. As the electrical field tends to the\ncritical point, Landau level expansion occurs. As a result, saturation of the\nHall conductance may be observed.",
        "positive": "Crossover from weak to strong coupling regime in dispersive circuit QED: We study the decoherence of a superconducting qubit due to the dispersive\ncoupling to a damped harmonic oscillator. We go beyond the weak\nqubit-oscillator coupling, which we associate with a phase Purcell effect, and\nenter into a strong coupling regime, with qualitatively different behavior of\nthe dephasing rate. We identify and give a physicaly intuitive discussion of\nboth decoherence mechanisms. Our results can be applied, with small\nadaptations, to a large variety of other physical systems, e. g. trapped ions\nand cavity QED, boosting theoretical and experimental decoherence studies."
    },
    {
        "anchor": "Tunable plasmons in ultrathin metal films: The physics of electrons, photons, and their plasmonic interactions changes\ngreatly when one or more dimensions are reduced down to the nanometer scale.\nFor example, graphene shows unique electrical, optical, and plasmonic\nproperties, which are tunable through gating or chemical doping. Similarly,\nultrathin metal films (UTMFs) down to atomic thickness can possess new quantum\noptical effects, peculiar dielectric properties, and predicted strong plasmons.\nHowever, truly two-dimensional plasmonics in metals has so far elusive because\nof the difficulty in producing large areas of sufficiently thin continuous\nfilms. Thanks to a deposition technique that allows percolation even at 1 nm\nthickness, we demonstrate plasmons in few-nanometer gold UTMFs, with clear\nevidence of new dispersion regimes and large electrical tunability. Resonance\npeaks at 1.5-5 micrometer wavelengths are shifted by hundreds of nanometers and\namplitude-modulated by tens of per cent through gating using relatively low\nvoltages. The results suggest ways to use metals in plasmonic applications,\nsuch as electro-optic modulation, bio-sensing, and smart windows.",
        "positive": "Topological Josephson $\u03c6_0$-junctions: We study the effect of a magnetic field on the current-phase relation of a\ntopological Josephson junction formed by connecting two superconductors through\nthe helical edge states of a quantum spin-Hall insulator. We predict that the\nZeeman effect along the spin quantization axis of the helical edges results in\nan anomalous Josephson relation that allows for a supercurrent to flow in the\nabsence of superconducting phase bias. We relate the associated field-tunable\nphase shift $\\phi_0$ in the Josephson relation of such a $\\phi_0$-junction to\nthe existence of a so-called helical superconductivity, which may result from\nthe interplay of the Zeeman effect and spin-orbit coupling. We analyze the\ndependence of the magneto-supercurrent on the junction length and discuss its\nobservability in suitably designed hybrid structures subject to an in-plane\nmagnetic field."
    },
    {
        "anchor": "High Density, Localized Quantum Emitters in Strained 2D Semiconductors: Two-dimensional chalcogenide semiconductors have recently emerged as a host\nmaterial for quantum emitters of single photons. While several reports on\ndefect and strain-induced single photon emission from 2D chalcogenides exist, a\nbottom-up, lithography-free approach to producing a high density of emitters\nremains elusive. Further, the physical properties of quantum emission in the\ncase of strained 2D semiconductors are far from being understood. Here, we\ndemonstrate a bottom-up, scalable, and lithography-free approach to creating\nlarge areas of localized emitters with high density (~150 emitters/um2) in a\nWSe2 monolayer. We induce strain inside the WSe2 monolayer with high spatial\ndensity by conformally placing the WSe2 monolayer over a uniform array of Pt\nnanoparticles with a size of 10 nm. Cryogenic, time-resolved, and gate-tunable\nluminescence measurements combined with near-field luminescence spectroscopy\nsuggest the formation of localized states in strained regions that emit single\nphotons with a high spatial density. Our approach of using a metal nanoparticle\narray to generate a high density of strained quantum emitters opens a new path\ntowards scalable, tunable, and versatile quantum light sources.",
        "positive": "Critical Resistivity along the Quantum Hall Liquid--Insulator Transition\n  Line: The critical resistivity measured along the quantum Hall liquid--insulator\ntransition line indicates a pronounced peak at a critical filling factor close\nto 1, which marks the crossover from the high to low magnetic field regime in\nthe phase diagram. The origin of this behavior is explained in the framework of\nclassical transport in a puddle network model. The proposed scenario is also\nconsistent with the behavior of the critical Hall resistance along the\ntransition line. In addition, a formula is suggested as a fit for isotherms\n($\\rho_{xx}$ vs. $\\nu$) in the moderately high field regime, which exhibits a\nviolation of duality symmetry as the critical resistivity is evelated from the\n`universal' value $h/e^2$."
    },
    {
        "anchor": "Synchronization of spin torque oscillators through spin Hall\n  magnetoresistance: Spin torque oscillators placed onto a nonmagnetic heavy metal show\nsynchronized auto-oscillations due to the coupling originating from spin Hall\nmagnetoresistance effect. Here, we study a system having two spin torque\noscillators under the effect of the spin Hall torque, and show that switching\nthe external current direction enables us to control the phase difference of\nthe synchronization between in-phase and antiphase.",
        "positive": "Integrating Functional Oxides with Graphene: Graphene-oxide hybrid structures offer the opportunity to combine the\nversatile functionalities of oxides with the excellent electronic transport in\ngraphene. Understanding and controlling how the dielectric environment affects\nthe intrinsic properties of graphene is also critical to fundamental studies\nand technological development of graphene. Here we review our recent effort on\nunderstanding the transport properties of graphene interfaced with\nferroelectric Pb(Zr,Ti)O_3 (PZT) and high-k HfO_2. Graphene field effect\ndevices prepared on high-quality single crystal PZT substrates exhibit up to\ntenfold increases in mobility compared to SiO_2-gated devices. An unusual and\nrobust resistance hysteresis is observed in these samples, which is attributed\nto the complex surface chemistry of the ferroelectric. Surface polar optical\nphonons of oxides in graphene transistors play an important role in the device\nperformance. We review their effects on mobility and the high source-drain bias\nsaturation current of graphene, which are crucial for developing graphene-based\nroom temperature high-speed amplifiers. Oxides also introduce scattering\nsources that limit the low temperature electron mobility in graphene. We\npresent a comprehensive study of the transport and quantum scattering times to\ndifferentiate various scattering scenarios and quantitatively evaluate the\ndensity and distribution of charged impurities and the effect of dielectric\nscreening. Our results can facilitate the design of multifunctional\nnano-devices utilizing graphene-oxide hybrid structures."
    },
    {
        "anchor": "Separation and acceleration of analogues of magnetic monopoles in\n  semiconductor microcavities: Half-integer topological defects in polariton condensates can be regarded as\nmagnetic charges, with respect to built-in effective magnetic fields present in\nmicrocavities. We show how an integer topological defect can be separated into\na pair of half-integer ones, paving the way towards flows of magnetic charges:\nspin currents or magnetricity. We discuss the corresponding experimental\nimplementation within microwires (with half-solitons) and planar microcavities\n(with half-vortices).",
        "positive": "Gate controlled unitary operation on flying spin qubits in quantum Hall\n  edge states: Spin and orbital freedoms of electrons traveling on spin-resolved quantum\nHall edge states (quantum Hall ferromagnets) are maximally entangled. The\nunitary operations on these two freedoms are hence equivalent, which means one\ncan manipulate the spins with non-magnetic methods through the orbitals. If one\ntakes the quantization axis of spins along the magnetization axis, the zenith\nangle is determined by the partition rate of spin-separated edges while the\nazimuth angle is defined as the phase difference between the edges. Utilizing\nthese properties, we have realized electrically controlled unitary operation on\nthe electron spins on the quantum Hall ferromagnets. The zenith angle of the\nspin was controlled through the radius of gyration at a corner by means of\napplying voltage to a thin gate placed at one edge. The subsequent rotation in\nthe azimuth angle was controlled via the distance between the edge channels\nalso by a gate voltage. The combination of the two operations constitutes the\nfirst systematic electric operation on spins in the quantum Hall edge channels."
    },
    {
        "anchor": "Universal optical polarizability for plasmonic nanostructures: We develop an analytical model for calculation of optical spectra for metal\nnanostructures of arbitrary shape supporting localized surface plasmons (LSPs).\nFor plasmonic systems with characteristic size below the diffraction limit, we\nobtain an explicit expression for optical polarizability that describes the\nlineshape of optical spectra solely in terms of the metal dielectric function\nand LSP frequency. The amplitude of the LSP spectral band is determined by the\neffective system volume that, for long-wavelength LSPs, can significantly\nexceed the physical volume of metal nanostructure. Within the quasistatic\napproach, we derive the exact LSP Green's function and establish general\nspectral properties of LSPs, including the distribution and oscillator strength\nof the LSP states. These results can be used to model or interpret the\nexperimental spectra of plasmonic nanostructures and to tune their optical\nproperties for various applications.",
        "positive": "Carbon Nanotube Thermal Transport: Ballistic to Diffusive: We propose to use l_0/(l_0+L) for the energy transmission covering both\nballistic and diffusive regimes, where l_0 is mean free path and L is system\nlength. This formula is applied to heat conduction in carbon nanotubes (CNTs).\nCalculations of thermal conduction show: (1) Thermal conductance at room\ntemperature is proportional to the diameter of CNTs for single-walled CNTs\n(SWCNTs) and to the square of diameter for multi-walled CNTs (MWCNTs). (2)\nInterfaces play an important role in thermal conduction in CNTs due to the\nsymmetry of CNTs vibrational modes. (3) When the phonon mean free path is\ncomparable with the length L of CNTs in ballistic-diffusive regime, thermal\nconductivity \\kappa goes as L^{\\alpha} . The effective exponent \\alpha is\nnumerically found to decrease with increasing temperature and is insensitive to\nthe diameter of SWCNTs for Umklapp scattering process. For short SWCNTs (<0.1\n\\mu m) we find \\alpha \\approx 0.8 at room temperature. These results are\nconsistent with recent experimental findings."
    },
    {
        "anchor": "Tuning plasmon excitations in pure and transition metal-doped arrays of\n  noble metal nanochains: We study the plasmonic properties of coupled noble-metal nanochains in the\ncase of different number of coupled chains and doping by different\ntransition-metal (TM) atoms within the time-dependent density-functional theory\n(TDDFT) approach. We find that as the number of chains in the array increases\nthe plasmon peak shifts from the sub-eV towards the visible range. As doping\nwith TM atoms increases, the visible absorption band broadens, owing to\nformation of additional plasmon peaks. The optical response is very sensitive\nto the type of doped atoms, their number and position; in particular, the\nadditional peaks are most pronounced in the case of weak doping when they\ncorrespond to local plasmon oscillations around the impurity atom. These\neffects have a potential to be used in various modern technologies, from\nsensors to solar cells. Most of the studies of nano-plasmon effects have been\nfocused on alkali- and noble-metal systems with extended s-electron states,\nwhile it was believed that doping with TM atoms with their more localized\ncharge as a rule leads to an attenuation of the plasmon modes. We demonstrate\nthat TM atoms can play a constructive role in plasmon generation in small chain\nsystems, and that plasmonic modes can emerge even in some pure TM nanochains.",
        "positive": "Emergence of Correlations in Alternating Twist Quadrilayer Graphene: Recently, alternating twist multilayer graphene (ATMG) has emerged as a\nfamily of moir\\'e systems that share several fundamental properties with\ntwisted bilayer graphene, and are expected to host similarly strong\nelectron-electron interactions near the magic angle. Here, we study alternating\ntwist quadrilayer graphene (ATQG) samples with twist angles of 1.96{\\deg} and\n1.52{\\deg}, which are slightly removed from the magic angle of 1.68{\\deg}. At\nthe larger angle, we find signatures of correlated insulators only when the\nATQG is hole doped, and no signatures of superconductivity, and for the smaller\nangle we find evidence of superconductivity, while signs of the correlated\ninsulators weaken. Our results provide insight into the twist angle dependence\nof correlated phases in ATMG and shed light on the nature of correlations in\nthe intermediate coupling regime at the edge of the magic angle range where\ndispersion and interaction are of the same order."
    },
    {
        "anchor": "Spin and rotational symmetries in unrestricted Hartree Fock states of\n  quantum dots: Ground state energies are obtained using the unrestricted Hartree Fock method\nfor up to four interacting electrons parabolically confined in a quantum dot\nsubject to a magnetic field. Restoring spin and rotational symmetries we\nrecover Hund first rule. With increasing magnetic field, crossovers between\nground states with different quantum numbers are found for fixed electron\nnumber that are not reproduced by the unrestricted Hartree Fock approximation.\nThese are consistent with the ones obtained with more refined techniques. We\nconfirm the presence of a spin blockade due to a spin mismatch in the ground\nstates of three and four electrons.",
        "positive": "Electronic Conduction in Short DNA Wires: A strict method is used to calculate the current-voltage characteristics of a\ndouble-stranded DNA. A more reliable model considering the electrostatic\npotential drop along an individual DNA molecular wire between the contacts is\nconsidered and the corresponding Green's Function is obtained analytically\nusing Generating Function method, which avoids difficult numerical evaluations.\nThe obtained results indicate that the electrostatic drop along the wire always\nincreases the conductor beyond the threshold than without considering it, which\nis in agreement with recent experiments. The present method can also be used to\ncalculate the current-voltage characteristics for other molecular wires of\narbitrary length."
    },
    {
        "anchor": "NIR Schottky Photodetectors Based on Individual Single-Crystalline GeSe\n  Nanosheet: We have synthesized high-quality, micrometer-sized, single-crystal GeSe\nnanosheets using vapor transport and deposition techniques. Photoresponse is\ninvestigated based on mechanically exfoliated GeSe nanosheet combined with Au\ncontacts under a global laser irradiation scheme. The nonlinearship,\nasymmetric, and unsaturated characteristics of the I-V curves reveal that two\nuneven back-to-back Schottky contacts are formed. First-principles calculations\nindicate that the occurrence of defects-induced in-gap defective states, which\nare responsible for the slow decay of the current in the OFF state and for the\nweak light intensity dependence of photocurrent. The Schottky photodetector\nexhibits a marked photoresponse to NIR light illumination at a wavelength of\n808 nm. The significant photoresponse and good responsitivity suggests its\npotential applications as photodetectors.",
        "positive": "Theory of subcycle time-resolved photoemission: application to terahertz\n  photodressing in graphene: Motivated by recent experimental progress we revisit the theory of pump-probe\ntime- and angle-resolved photoemission spectroscopy (trARPES), which is one of\nthe most powerful techniques to trace transient pump-driven modifications of\nthe electronic properties. The pump-induced dynamics can be described in\ndifferent gauges for the light-matter interaction. Standard minimal coupling\nleads to the velocity gauge, defined by linear coupling to the vector\npotential. In the context of tight-binding (TB) models, the Peierls\nsubstitution is the commonly employed scheme for single-band models.\nMulti-orbital extensions -- including the coupling of the dipole moments to the\nelectric field -- have been introduced and tested recently. In this work, we\nderive the theory of time-resolved photoemission within both gauges from the\nperspective of nonequilibrium Green's functions. This approach naturally\nincorporates the photoelectron continuum, which allows for a direct calculation\nof the observable photocurrent. Following this route we introduce\ngauge-invariant expressions for the time-resolved photoemission signal. The\ntheory is applied to graphene pumped with short terahertz pulses, which we\ntreat within a first-principles TB model. We investigate the gauge invariance\nand discuss typical effects observed in subcycle time-resolved photoemission.\nOur formalism is an ideal starting point for realistic trARPES simulations\nincluding scattering effects."
    },
    {
        "anchor": "Coulomb force mediated heat transfer in the near field - geometric\n  effect: It has been shown recently that the Coulomb part of electromagnetic\ninteractions is more important than transverse propagation waves for the\nnear-field enhancement of heat transfer between metal objects at a distance of\norder nanometers. Here we present a theory focusing solely on the Coulomb\npotential between electrons hopping among tight-binding sites. When the\nrelevant systems are reduced to very small geometry, for example, a single\nsite, the enhancement is much higher compared to a collection of them packed\nwithin a distance of a few angstroms. We credit this to the screening effect.\nThis result may be useful in designing metal-based meta-materials to enhance\nheat transfer much higher.",
        "positive": "A systematic study of structural, electronic and optical properties of\n  atomic scale defects in 2D transition metal dichalcogenides MX$_2$ (M = Mo,W;\n  X = S, Se, Te): In this work, we have systematically studied structural, electronic and\nmagnetic properties of atomic scale defects in 2D transition metal\ndichalcogenides MX$_2$, (M = Mo and W; X = S, Se and Te) by density functional\ntheory. Various types of defects, e.g., X vacancy, X interstitial, M vacancy, M\ninterstitial, MX and XX double vacancies have been considered. It has been\nfound that the X interstitial has the lowest formation energy ($\\sim$ 1 eV) for\nall the systems in the X--rich condition whereas for M--rich condition, X\nvacancy has the lowest formation energy except for \\ce{MTe2} systems. Both\nthese defects have very high equilibrium defect concentrations at growth\ntemperatures (1000K-1200K) reported in literature. A pair of defects, e.g., two\nX vacancies or one M and one X vacancies tend to occupy the nearest possible\ndistance. No trace of magnetism has been found for any one of the defects\nconsidered. Apart from X interstitial, all other defects have defect states\nappearing in the band gap, which can greatly affect the electronic and optical\nproperties of the pristine systems. Our calculated optical properties show that\nthe defect states cause optical transitions at $\\sim$ 1.0 eV, which can be\nbeneficial for light emitting devices. The results of our systematic study are\nexpected to guide the experimental nanoengineering of defects to achieve\nsuitable properties related to band gap modifications and characterization of\ndefect fingerprints via optical absorption measurements."
    },
    {
        "anchor": "Thermal metal in network models of a disordered two-dimensional\n  superconductor: We study the universality class for localization which arises from models of\nnon-interacting quasiparticles in disordered superconductors that have neither\ntime-reversal nor spin-rotation symmetries. Two-dimensional systems in this\ncategory, which is known as class D, can display phases with three different\ntypes of quasiparticle dynamics: metallic, localized, or with a quantized\n(thermal) Hall conductance. Correspondingly, they can show a variety of\ndelocalization transitions. We illustrate this behavior by investigating\nnumerically the phase diagrams of network models with the appropriate symmetry,\nand for the first time show the appearance of the metallic phase.",
        "positive": "Spin Proximity Effects in Graphene/Topological Insulator\n  Heterostructures: Enhancing the spin-orbit interaction in graphene, via proximity effects with\ntopological insulators, could create a novel 2D system that combines nontrivial\nspin textures with high electron mobility. In order to engineer practical\nspintronics applications with such graphene/topological insulator (Gr/TI)\nheterostructures, an understanding of the hybrid spin-dependent properties is\nessential. {However to date, despite the large number of experimental studies\non Gr/TI heterostructures reporting a great variety of remarkable (spin)\ntransport phenomena, little is known about the true nature of the spin texture\nof the interface states as well as their role on the measured properties. Here\nwe use {\\it ab initio} simulations and tight-binding models to determine the\nprecise spin texture of electronic states in graphene interfaced with a\nBi$_2$Se$_3$ topological insulator. Our calculations predict the emergence of a\ngiant spin lifetime anisotropy in the graphene layer, which should be a\nmeasurable hallmark of spin transport in Gr/TI heterostructures, and suggest\nnovel types of spin devices"
    },
    {
        "anchor": "Generalization of spectral bulk-boundary correspondence: The bulk-boundary correspondence in one dimension asserts that the physical\nquantities defined in the bulk and at the edge are connected, as well\nestablished in the argument for electric polarization. Recently, a spectral\nbulk-boundary correspondence (SBBC), an extended version of the conventional\nbulk-boundary correspondence to energy-dependent spectral functions, such as\nGreen's functions, has been proposed in chiral symmetric systems, in which the\nchiral operator anticommutes with the Hamiltonian. In this study, we extend the\nSBBC to a system with impurity scattering and dynamical self-energies,\nregardless of the presence or absence of a gap in the energy spectrum.\nMoreover, the SBBC is observed to hold even in a system without chiral\nsymmetry, which substantially generalizes its concept. The SBBC is demonstrated\nwith concrete models, such as superconducting nanowires and a\nSu-Schrieffer-Heeger model. Its potential applications and certain remaining\nissues are also discussed.",
        "positive": "Nonlinear Dynamics and Chaos in Two Coupled Nanomechanical Resonators: Two elastically coupled nanomechanical resonators driven independently near\ntheir resonance frequencies show intricate nonlinear dynamics. The dynamics\nprovide a scheme for realizing a nanomechanical system with tunable frequency\nand nonlinear properties. For large vibration amplitudes the system develops\nspontaneous oscillations of amplitude modulation that also show period doubling\ntransitions and chaos. The complex nonlinear dynamics are quantitatively\npredicted by a simple theoretical model."
    },
    {
        "anchor": "Analytical approach to the surface plasmon resonance characteristic of\n  metal nanoparticle dimer in dipole-dipole approximation: This theoretical study, deals with the effect of bi-particle interaction on\nthe surface plasmon resonance (SPR) in a dimer which includes two identical\nmetal nanoparticles (NPs). Considering the dipole-dipole interaction in a\nDrude-like model, an appropriate equation is derived for the permittivity of\neach NP. The restoration force related to the classical confinement originating\nfrom the finite size of NPs is considered and an appropriate adjustment\ncoefficient is considered for this term through analyzing experimental data.\nTwo different polarizations are considered for the laser beam electric field\nand it is shown that the orientation of electric field has essential role in\nthe linear optical properties of dimer. Numerical investigation is accomplished\nfor a dimer of gold NPs with two different diameters of 4nm and 20nm. For the\nparallel polarization, dipole-dipole interaction leads to the red-shift of SPR\nwavelength and increase in its peak value while for the perpendicular\npolarization, the absolutely opposite results are derived. For all cases, it is\nshown that SPR wavelength functionality with respect to the geometric factor\n$a/d$ (NP radius to the separation) can be presented by a cubic equation that\nfits better than an exponential one suggested by the earlier studies which\ndemonstrates the dipole-dipole characteristic of the interaction.\nQualitatively, our results are in good agreement with the other experimental\nstudies.",
        "positive": "Physical Vapor Transport Growth of Antiferromagnetic CrCl$_3$ Flakes\n  Down to Monolayer Thickness: The van der Waals magnets CrX$_3$ (X = I, Br, and Cl) exhibit highly tunable\nmagnetic properties and are promising candidates for developing novel\ntwo-dimensional (2D) magnetic devices such as magnetic tunnel junctions and\nspin tunneling transistors. Previous studies of CrCl$_3$ have mainly focused on\nmechanically exfoliated samples. Controlled synthesis of high quality\natomically thin flakes is critical for their technological implementation but\nhas not been achieved to date. Here, we report the growth of large CrCl$_3$\nflakes with well-defined facets down to monolayer thickness (~0.6 nm) via the\nphysical vapor transport technique. Both isolated flakes with well-defined\nfacets and long stripe samples with the trilayer portion exceeding 60 $\\mu$m\nhave been obtained. High-resolution transmission electron microscopy studies\nshow that the CrCl$_3$ flakes are single crystalline in the monoclinic\nstructure, consistent with the Raman results. The room temperature stability of\nthe CrCl$_3$ flakes decreases with decreasing thickness. The tunneling\nmagnetoresistance of graphite/CrCl$_3$/graphite tunnel junctions confirms that\nfew-layer CrCl$_3$ possesses in-plane magnetic anisotropy and N\\'eel\ntemperature of 17 K. Our study paves the path for developing CrCl$_3$-based\nscalable 2D spintronic applications."
    },
    {
        "anchor": "Tilted Dirac Cones in Two-Dimensional Materials: Impact on Electron\n  Transmission and Pseudospin Dynamics: This study is devoted to the profound implications of tilted Dirac cones on\nthe quantum transport properties of two-dimensional (2D) Dirac materials. These\nmaterials, characterized by their linear conic energy dispersions in the\nvicinity of Dirac points, exhibit unique electronic behaviors, including the\nemulation of massless Dirac fermions and the manifestation of relativistic\nphenomena such as Klein tunneling. Expanding beyond the well-studied case of\ngraphene, the manuscript focuses on materials with tilted Dirac cones, where\nthe anisotropic and tilted nature of the cones introduces additional complexity\nand richness to their electronic properties. The investigation begins by\nconsidering a heterojunction of 2D Dirac materials, where electrons undergo\nquantum tunneling between regions with upright and tilted Dirac cones. The role\nof tilt in characterizing the transmission of electrons across these interfaces\nis thoroughly examined, shedding light on the influence of the tilt parameter\non the transmission probability and the fate of the pseudospin of the Dirac\nelectrons, particularly upon a sudden change in the tilting. We also\ninvestigate the probability of reflection and transmission from an intermediate\nslab with arbitrary subcritical tilt, focusing on the behavior of electron\ntransmission across regions with varying Dirac cone tilts. The study\ndemonstrates that for certain thicknesses of the middle slab, the transmission\nprobability is equal to unity, and both reflection and transmission exhibit\nperiodic behavior with respect to the slab thickness.",
        "positive": "Estimation of spin relaxation lengths in spin valves of In and In2O3\n  nanostructures: We report the electrical injection and detection of spin polarized current in\nlateral ferromagnet-nonmagnet-ferromagnet spin valve devices, ferromagnet being\ncobalt and nonmagnet being indium (In) or indium oxide (In2O3) nanostructures.\nThe In nanostructures were grown by depositing pure In on lithographically\npre-patterned structures. In2O3 nanostructures were obtained by oxidation of In\nnanostructures. Spin valve devices were fabricated by depositing micro magnets\nover the nanostructures with connecting nonmagnetic electrodes via two steps of\ne-beam lithography. Clear spin switching behavior was observed in the both\ntypes of spin valve devices measured at 10 K. From the measured spin signal,\nthe spin relaxation length ({\\lambda}N) of In and In2O3 nanostructures were\nestimated to be 449.6 nm and 788.6 nm respectively."
    },
    {
        "anchor": "Nonlinear Seebeck effect of SU($N$) Kondo impurity: We develop a theoretical framework to study the influences of coupling\nasymmetry on the thermoelectrics of a strongly coupled SU($N$) Kondo impurity\nbased on a local Fermi liquid theory. Applying non-equilibrium Keldysh\nformalism, we investigate charge current driven by the voltage bias and\ntemperature gradient in the strong coupling regime of an asymmetrically coupled\nSU($N$) quantum impurity. The thermoelectric characterizations are made via\nnon-linear Seebeck effects. We demonstrate that the beyond particle-hole (PH)\nsymmetric SU($N$) Kondo variants are highly desirable with respect to the\ncorresponding PH symmetric setups in order to have significantly improved\nthermoelectric performance. The greatly enhanced Seebeck coefficients by\ntailoring the coupling asymmetry of beyond PH symmetric SU($N$) Kondo effects\nare explored. Apart from presenting the analytical expressions of asymmetry\ndependent transport coefficients for general SU($N$) Kondo effects, we make a\nclose connection of our findings with the experimentally studied SU(2) and\nSU(4) Kondo effects in quantum dot nano structures. Seebeck effects associated\nwith the theoretically proposed SU(3) Kondo effects are discussed in detail.",
        "positive": "Transmission through a boundary between monolayer and bilayer graphene: The electron transmission between monolayer and bilayer graphene is\ntheoretically studied for zigzag and armchair boundaries within an\neffective-mass scheme. Due to the presence of an evanescent wave in the bilayer\ngraphene, traveling modes are well connected to each other. The transmission\nthrough the boundary is strongly dependent on the incident angle and the\ndependence is opposite between the K and K' points, leading to valley\npolarization of transmitted wave."
    },
    {
        "anchor": "Direct Measurement of the Spin-Orbit Interaction in a Two-Electron InAs\n  Nanowire Quantum Dot: We demonstrate control of the electron number down to the last electron in\ntunable few-electron quantum dots defined in catalytically grown InAs\nnanowires. Using low temperature transport spectroscopy in the Coulomb blockade\nregime we propose a simple method to directly determine the magnitude of the\nspin-orbit interaction in a two-electron artificial atom with strong spin-orbit\ncoupling. Due to a large effective g-factor |g*|=8+/-1 the transition from\nsinglet S to triplet T+ groundstate with increasing magnetic field is dominated\nby the Zeeman energy rather than by orbital effects. We find that the\nspin-orbit coupling mixes the T+ and S states and thus induces an avoided\ncrossing with magnitude $\\Delta_{SO}$=0.25+/-0.05 meV. This allows us to\ncalculate the spin-orbit length $\\lambda_{SO}\\approx$127 nm in such systems\nusing a simple model.",
        "positive": "Passive stabilization of hole spin qubit using optical Stark effect: The extrinsic dephasing of a hole spin confined to a self-assembled quantum\ndot is dominated by charge noise acting on an electric-field dependent\ng-factor. Here we propose the use of the optical Stark effect to reduce the\nsensitivity of the effective hole Zeeman energy to fluctuations in the local\nelectric-field. Calculations using measured quantum dot parameters are\npresented, and demonstrate a factor of 10-100 reduction in the extrinsic\ndephasing. Compared to active stabilization methods, this technique should\nbenefit from reduced experimental complexity."
    },
    {
        "anchor": "Superconductor/Ferromagnet Heterostructures: A Platform for\n  Superconducting Spintronics and Quantum Computation: The interplay between superconductivity and ferromagnetism in the\nsuperconductor/ferromagnet (SC/FM) heterostructures generates many interesting\nphysical phenomena, including spin-triplet superconductivity, superconducting\norder parameter oscillation, and topological superconductivity. The unique\nphysical properties make the SC/FM heterostructures as promising platforms for\nfuture superconducting spintronics and quantum computation applications. In\nthis article, we review important research progress of SC/FM heterostructures\nfrom superconducting spintronics to quantum computation, and it is organized as\nfollows. Firstly, we discuss the progress of spin current carriers in SC/FM\nheterostructures including Bogoliubov quasiparticles, superconducting vortex,\nand spin-triplet Cooper pairs which might be used for long-range spin\ntransport. Then, we will describe the {\\pi} Josephson junctions and its\napplication for constructing {\\pi} qubits. Finally, we will briefly review\nexperimental signatures of Majorana states in the SC/FM heterostructures and\nthe theoretically proposed manipulation, which could be useful to realize\nfault-tolerant topological quantum computing.",
        "positive": "Dissipation in mesoscale superfluids: We investigate the maximum speed at which a driven superfluid can flow\nthrough a narrow constriction with a size on the order of the healing length.\nConsidering dissipation via the thermal nucleation of quantized vortices, we\ncalculate the critical velocity for superfluid $^4$He and ultracold atomtronic\ncircuits, identify fundamental length and velocity scales, and are thus able to\npresent results obtained in widely different temperature and density ranges in\na universal framework. For ultra-narrow channels we predict a drastic reduction\nin the critical velocity as the energy barrier for flow reducing thermally\nactivated phase slip fluctuations is suppressed."
    },
    {
        "anchor": "Coulomb Promotion of Spin-Dependent Tunnelling: We study transport of spin-polarized electrons through a magnetic\nsingle-electron transistor (SET) in the presence of an external magnetic field.\nAssuming the SET to have a nanometer size central island with a single electron\nlevel we find that the interplay on the island between coherent spin-flip\ndynamics and Coulomb interactions can make the Coulomb correlations promote\nrather than suppress the current through the device. We find the criteria for\nthis new phenomenon -- Coulomb promotion of spin-dependent tunnelling -- to\noccur.",
        "positive": "Zitterbewegung Effect in Graphene with Spacially Modulated Potential: The Zitterbewegung (ZB) effect is investigated in graphene with spacially\nmodulated potential near the original Dirac point (ODP) and extra Dirac points\n(EDPs). Our calculations show that to get the large ZB oscillations, the wave\npacket center must be at the angle $\\theta_0=0$ for EDPs located at\nzero-energy, or $\\theta_0=\\pi/2$ for both ODP and EDPs at finite energy\n$\\varepsilon=m\\pi$ ($m$ integer). By varying the parameters ($q_2, \\mathbb{V}$)\nof the periodic potential and the initial momentum ($\\kappa_0, \\theta_0$) of\nGaussian wave packet, it is found that the frequency of the ZB oscillations is\nin the range $[10^{7}~\\text{Hz}, 10^{13}~\\text{Hz}$] depending on what type of\nEDP is generated and the amplitude reaches hundreds of angstroms but their\nattenuation becomes very slow. More analysis of the frequency shows the\npossibilities in experimentally realizing the ZB effect in our system."
    },
    {
        "anchor": "Direct visualization and effects of atomic-scale defects on the\n  optoelectronic properties of hexagonal boron nitride: Hexagonal boron nitride (hBN) is attracting a lot of attention in the last\nyears, thanks to its many remarkable properties. These include the presence of\nsingle-photon emitters with superior optical properties, which make it an ideal\ncandidate for a plethora of photonic technologies. However, despite the large\nnumber of experimental results and theoretical calculations, the structure of\nthe defects responsible for the observed emission is still under debate. In\nthis work, we visualize individual atomic-scale defects in hBN with atomic\nforce microscopy under ambient conditions and observe multiple narrow emission\nlines from optically stable emitters. This direct observation of the structure\nof the defects combined with density functional theory calculations of their\nband structures and electronic properties allows us to associate the existence\nof several single-photon transitions to the observed defects. Our work sheds\nlight on the origin of single-photon emission in hBN that is important for the\nunderstanding and tunability of high-quality emitters in optoelectronics and\nquantum technologies.",
        "positive": "The Role of Spin-Dependent Interface Scattering in Generating\n  Current-Induced Torques in Magnetic Multilayers: We present a calculation of current-induced torques in metallic magnetic\nmultilayers derived from the spin-dependent transmission and reflection\nproperties of the magnetic layers. A scattering formalism is employed to\ncalculate the torques in a magnetic-nonmagnetic-magnetic trilayer, for currents\nperpendicular to the layers, in both the ballistic and diffusive regimes."
    },
    {
        "anchor": "Multi-component plasmons in monolayer MoS$_2$ with circularly polarized\n  optical pumping: By making use of circularly polarized light and electrostatic gating,\nmonolayer molybdenum disulfide (ML-MoS$_2$) can form a platform supporting\nmultiple types of charge carriers. They can be discriminated by their spin,\nvalley index or whether they're electrons or holes. We investigate the\ncollective properties of those charge carriers and are able to identify new\ndistinct plasmon modes. We analyze the corresponding dispersion relation,\nlifetime and oscillator strength, and calculate the phase relation between the\noscillations in the different components of the plasmon modes. All platforms in\nML-MoS$_2$ support a long-wavelength $\\sqrt{q}$ plasmon branch at zero Kelvin.\nIn addition to this, for an $n$-component system, $n-1$ distinct plasmon modes\nappear as acoustic modes with linear dispersion in the long-wavelength limit.\nThese modes correspond to out-of-phase oscillations in the different Fermion\nliquids and have, although being damped, a relatively long lifetime.\nAdditionally, we also find new distinct modes at large wave vector that are\nstronger damped by intra-band processes.",
        "positive": "Device Architecture for Coupling Spin Qubits Via an Intermediate Quantum\n  State: We demonstrate a scalable device architecture that facilitates indirect\nexchange between singlet-triplet spin qubits, mediated by an intermediate\nquantum state. The device comprises five quantum dots, which can be\nindependently loaded and unloaded via tunneling to adjacent reservoirs,\navoiding charge latch-up common in linear dot arrays. In a step towards\nrealizing two-qubit entanglement based on indirect exchange, the architecture\npermits precise control over tunnel rates between the singlet-triplet qubits\nand the intermediate state. We show that by separating qubits by 1 um, the\nresidual capacitive coupling between them is reduced to 7 ueV."
    },
    {
        "anchor": "Measurement of the \u03bd= 1/3 fractional quantum Hall energy gap in\n  suspended graphene: We report on magnetotransport measurements of multi-terminal suspended\ngraphene devices. Fully developed integer quantum Hall states appear in\nmagnetic fields as low as 2 T. At higher fields the formation of longitudinal\nresistance minima and transverse resistance plateaus are seen corresponding to\nfractional quantum Hall states, most strongly for {\\nu}= 1/3. By measuring the\ntemperature dependence of these resistance minima, the energy gap for the 1/3\nfractional state in graphene is determined to be at ~20 K at 14 T.",
        "positive": "On-Chip Single Plasmon Detection: Surface plasmon polaritons (plasmons) have the potential to interface\nelectronic and optical devices. They could prove extremely useful for\nintegrated quantum information processing. Here we demonstrate on-chip\nelectrical detection of single plasmons propagating along gold waveguides. The\nplasmons are excited using the single-photon emission of an optically emitting\nquantum dot. After propagating for several micrometers, the plasmons are\ncoupled to a superconducting detector in the near-field. Correlation\nmeasurements prove that single plasmons are being detected."
    },
    {
        "anchor": "Strong nonlocal tuning of the current-phase relation of a quantum dot\n  based Andreev molecule: Multiple systems hosting Andreev molecular states have been proposed and\nstudied, consisting of closely spaced Josephson junctions modeled as ballistic\nchannels. We show that replacing the ballistic channels in the weak link of the\nJosephson junctions with quantum dots (QD), leads to a very exciting, rich\nphase diagram. It shows a strong nonlocal Josephson effect: as one junction is\ntuned the current-phase relation of the other junction is modified. This\narchitecture hosts $0 - \\pi$ transitions and shows a tunable anomalous\nphase-shift $\\phi_0$ , nonlocally controlled in both cases, without relying on\nspin-orbit interaction or Zeeman fields. In addition significant\nsuperconducting diode effect can also be observed. The presented non-local\ncurrent-phase relation can be used as a signature of the formation of an\nAndreev molecular state, as well as to introduce new ways to tune quantum\narchitectures.",
        "positive": "Impact of Kondo correlations and spin-orbit coupling on spin-polarized\n  transport in carbon nanotube quantum dot: Spin polarized transport through a quantum dot coupled to ferromagnetic\nelectrodes with noncollinear magnetizations is discussed in terms of\nnonequilibrium Green functions formalism in the finite-U slave boson mean field\napproximation. The difference of orientations of the magnetizations of\nelectrodes opens off-diagonal spin-orbital transmission and apart from spin\ncurrents of longitudinal polarization also spin-flip currents appear. We also\nstudy equilibrium pure spin current at zero bias and discuss its dependence on\nmagnetization orientation, spin-orbit coupling strength and gate voltage.\nImpact of these factors on tunneling magnetoresistance (TMR) is also\nundertaken. In general spin-orbit coupling weakens TMR, but it can change its\nsign."
    },
    {
        "anchor": "Giant Magnetoresistance in Bilayer Graphene Nanoflakes: Coherent spin transport through bilayer graphene (BLG) nanoflakes sandwiched\nbetween two electrodes made of single-layer zigzag graphene nanoribbon was\ninvestigated by means of Landauer-Buttiker formalism. Application of a magnetic\nfield only on BLG structure as a channel produces a perfect spin polarization\nin a large energy region. Moreover, the conductance could be strongly modulated\nby magnetization of the zigzag edge of AB-stacked BLG, and the junction,\nentirely made of carbon, produces a giant magnetoresistance (GMR) up to\n$10^6\\%$. Intestinally, GMR and spin polarization could be tuned by varying BLG\nwidth and length. Generally, MR in a AB-stacked BLG strongly increases\n(decreases) with length (width).",
        "positive": "Thermal conductance and noise of Majorana modes along interfaced\n  $\u03bd=5/2$ fractional quantum Hall states: We study transport along interfaced edge segments of fractional quantum Hall\nstates hosting non-Abelian Majorana modes. With an incoherent model approach,\nwe compute, for edge segments based on Pfaffian, anti-Pfaffian, and\nparticle-hole-Pfaffian topological orders, thermal conductances, voltage biased\nnoise, and delta-$T$ noise. We determine how the thermal equilibration of edge\nmodes impacts these observables and identify the temperature scalings of\ntransitions between regimes of differently quantized thermal conductances. In\ncombination with recent experimental data, we use our results to estimate\nthermal and charge equilibration lengths in real devices. We also propose an\nexperimental setup which permits measuring several transport observables for\ninterfaced fractional quantum Hall edges in a single device. It can, e.g., be\nused to rule out edge reconstruction effects. In this context, we further point\nout some subtleties in two-terminal thermal conductance measurements and how to\nremedy them. Our findings are consistent with recent experimental results\npointing towards a particle-hole-Pfaffian topological order at filling\n$\\nu=5/2$ in GaAs/AlGaAs, and provide further means to pin-point the edge\nstructure at this filling and possibly also other exotic fractional quantum\nHall states."
    },
    {
        "anchor": "Analytic model of effective screened Coulomb interactions in a\n  multilayer system: The main objective of the present work is the development of an analytically\ntractable model of screened electron-electron and electron-exciton interactions\nin layered systems composed of two parallel semiconductor quantum wells\nseparated by a dielectric layer. These systems are promising for\nsuperconductivity with excitons-polaritons, and spin manipulation. Polarization\neffects induced by the dielectric mismatch in the nanostructure are taken into\naccount using the image charge method. The obtained analytic expressions are\nused to calculate screened electron-electron and electron-exciton interactions;\nthese are compared to results computed using other recently published models.",
        "positive": "Imaging and tuning polarity at SrTiO3 domain walls: Electrostatic fields tune the ground state of interfaces between complex\noxide materials. Electronic properties, such as conductivity and\nsuperconductivity, can be tuned and then used to create and control circuit\nelements and gate-defined devices. Here we show that naturally occurring twin\nboundaries, with properties that are different from their surrounding bulk, can\ntune the LaAlO3/SrTiO3 interface 2DEG at the nanoscale. In particular, SrTiO3\ndomain boundaries have the unusual distinction of remaining highly mobile down\nto low temperatures, and were recently suggested to be polar. Here we apply\nlocalized pressure to an individual SrTiO3 twin boundary and detect a change in\nLaAlO3/SrTiO3 interface current distribution. Our data directly confirm the\nexistence of polarity at the twin boundaries, and demonstrate that they can\nserve as effective tunable gates. As the location of SrTiO3 domain walls can be\ncontrolled using external field stimuli, our findings suggest a novel approach\nto manipulate SrTiO3-based devices on the nanoscale."
    },
    {
        "anchor": "Delocalized states in three-terminal superconductor-semiconductor\n  nanowire devices: We fabricate three-terminal hybrid devices with a nanowire segment\nproximitized by a superconductor, and with two tunnel probe contacts on either\nside of that segment. We perform simultaneous tunneling measurements on both\nsides. We identify some states as delocalized above-gap states observed on both\nends, and some states as localized near one of the tunnel barriers. Delocalized\nstates can be traced from zero to finite magnetic fields beyond 0.5 T. In the\nparameter regime of delocalized states, we search for correlated subgap\nresonances required by the Majorana zero mode hypothesis. While both sides\nexhibit ubiquitous low-energy features at high fields, no correlation is\ninferred. Simulations using a one-dimensional effective model suggest that\ndelocalized states may belong to lower one-dimensional subbands, while the\nlocalized states originate from higher subbands. To avoid localization in\nhigher subbands, disorder may need to be further reduced to realize Majorana\nzero modes.",
        "positive": "Transformation optics: a time- and frequency-domain analysis of\n  electron-energy loss spectroscopy: Electron energy loss spectroscopy (EELS) and Cathodoluminescence (CL) play a\npivotal role in many of the cutting edge experiments in plasmonics. EELS and CL\nexperiments are usually supported by numerical simulations, which, whilst\naccurate, may not provide as much physical insight as analytical calculations\ndo. Fully analytical solutions to EELS and CL systems in plasmonics are rare\nand difficult to obtain. This paper aims to narrow this gap by introducing a\nnew method based on Transformation optics that allows to calculate the\nquasi-static frequency and time-domain response of plasmonic particles under\nelectron beam excitation."
    },
    {
        "anchor": "Omnidirectional spin-to-charge conversion in graphene/NbSe$_2$ van der\n  Waals heterostructures: The conversion of spin currents polarized in different directions into charge\ncurrents is a keystone for novel spintronic devices. Van der Waals\nheterostructures with tailored symmetry are a very appealing platform for such\na goal. Here, by performing nonlocal spin precession experiments, we\ndemonstrate the spin-to-charge conversion (SCC) of spins oriented in all three\ndirections (x, y, and z). By analyzing the magnitude and temperature dependence\nof the signal in different configurations, we argue that the different SCC\ncomponents measured are likely due to spin-orbit proximity and broken symmetry\nat the twisted graphene/NbSe$_2$ interface. Such efficient omnidirectional SCC\nopens the door to the use of new architectures in spintronic devices, from\nspin-orbit torques that can switch any magnetization to the magnetic state\nreadout of magnetic elements pointing in any direction.",
        "positive": "Stochastic many-body perturbation theory for Moir\u00e9 states in twisted\n  bilayer phosphorene: A new implementation of stochastic many-body perturbation theory for periodic\n2D systems is presented. The method is used to compute quasiparticle\nexcitations in twisted bilayer phosphorene. Excitation energies are studied\nusing stochastic $G_0W_0$ and partially self-consistent $\\bar \\Delta GW_0$\napproaches. The approach is inexpensive; it is used to study twisted systems\nwith unit cells containing $>2,700$ atoms ($>13,500$ valence electrons), which\ncorresponds to a minimum twisting angle of $\\approx 3.1^\\circ$. Twisted\nbilayers exhibit band splitting, increased localization and formation of\nlocalized Moir\\'e impurity states, as documented by band-structure unfolding.\nStructural changes in twisted structures lift band degeneracies. Energies of\nthe impurity states vary with the twisting angle due to an interplay between\nnon-local exchange and polarization effects. The mechanisms of quasiparticle\nenergy (de)stabilization due to twisting are likely applicable to a wide range\nof low-dimensional Moir\\'{e} superstructures."
    },
    {
        "anchor": "Dielectrophoretic assembly of liquid-phase-exfoliated TiS3 nanoribbons\n  for photodetecting applications: Liquid-phase-exfoliation is a technique capable of producing large quantities\nof two-dimensional material in suspension. Despite many efforts in the\noptimization of the exfoliation process itself not much has been done towards\nthe integration of liquid-phase-exfoliated materials in working solid-state\ndevices. In this article, we use dielectrophoresis to direct the assembly of\nliquid-phase-exfoliated TiS3 nanoribbons between two gold electrodes to produce\nphotodetectors working in the visible. Through electrical and optical\nmeasurements we characterize the responsivity of the device and we find values\nas large as 3.8 mA/W, which improve of more than one order of magnitude on the\nstate-of-the-art for devices based on liquid-phase-exfoliated two-dimensional\nmaterials assembled by drop-casting or ink-jet methods.",
        "positive": "Unraveling the electronic structure of narrow atomically-precise chiral\n  graphene nanoribbons: Recent advances in graphene nanoribbon-based research have demonstrated the\ncontrolled synthesis of chiral graphene nanoribbons (cGNR) with atomic\nprecision using strategies of on-surface chemistry. However their electronic\ncharacterization, including typical figures of merit like band gap or frontier\nbands effective masses, has not yet been reported. In this work, we provide a\ndetailed characterization of (3,1)-cGNRs on Au(111). The structure and epitaxy,\nas well as the electronic band structure of the ribbons, are analyzed by means\nof scanning tunneling microscopy and spectroscopy, angle resolved photoemission\nand density functional theory."
    },
    {
        "anchor": "Exploring ideas in topological quantum phenomena: A journey through the\n  SSH model: Geared as an invitation for undergraduates, beginning graduate students, we\npresent a pedagogical introduction to one-dimensional topological phases -- in\nparticular the Su-Schrieffer-Heeger model. In the process, we delve upon ideas\nof entanglement using the correlator method and the von-Neumann density-matrix\nmethod, geometric phase, polarization, transport signatures and the role of\nelectron-electron interactions. Through hands-on numerical experiments, whose\n$\\href{https://github.com/hnoend/SSH_codes}{codes}$ are shared, we try to drive\nhome the message why a program of simulating quantum electronics with\ntopological toy models is the store house for discovering fantastic physics\nideas.",
        "positive": "Magnon spin current induced by triplet Cooper pair supercurrents: At the interface between a ferromagnetic insulator and a superconductor there\nis a coupling between the spins of the two materials. We show that when a\nsupercurrent carried by triplet Cooper pairs flows through the superconductor,\nthe coupling induces a magnon spin current in the adjacent ferromagnetic\ninsulator. The effect is dominated by Cooper pairs polarized in the same\ndirection as the ferromagnetic insulator, so that charge and spin supercurrents\nproduce similar results. Our findings demonstrate a way of converting Cooper\npair supercurrents to magnon spin currents."
    },
    {
        "anchor": "Four kinetic energy formulas for studying the interaction of energetic\n  ions with carbon nanotubes: Three questions should be interesting, for better understanding of the basic\nphysics of damage creation and stopping ions of different types, in the damaged\ntube: 1) Between the mass and charge effects, i.e. potential- independent and\npotential- dependent effects on the damaged tube, Which ones may the cross-\nsection $\\sigma$ effects belong to? 2) One method has calculated number of\nenergetic recoils (both ions and carbon atoms), which hit the metal layer below\nthe damaged tube, to study the stopping of both incident ions and recoil carbon\natoms in it. Another method has calculated the ion- deposited energy\n$E_0-E_{penetrating}$ in the damaged tube, to distinguish between penetrating\nand stopped ions. Which method is better for studying the stopping between two\nones? 3) Why can tens of the graphitic shells easily stop energetic ions with\nenergies up to 10 keV? Which effects on the stopping? In kinetic energy\nformulas, we give answers for discussion.",
        "positive": "Observing the universal screening of a Kondo impurity: The Kondo effect, deriving from a local magnetic impurity mediating\nelectron-electron interactions, constitutes a flourishing basis for\nunderstanding a large variety of intricate many-body problems. Its experimental\nimplementation in tunable circuits has made possible important advances through\nwell-controlled investigations. However, these have mostly concerned transport\nproperties, whereas thermodynamic observations - notably the fundamental\nmeasurement of the spin of the Kondo impurity - remain elusive in test-bed\ncircuits. Here, with a novel combination of a \"charge\" Kondo circuit with a\ncharge sensor, we directly observe the state of the impurity and its\nprogressive screening. We establish the universal renormalization flow from a\nsingle free spin to a screened singlet, the associated reduction in the\nmagnetization, and the relationship between scaling Kondo temperature and\nmicroscopic parameters. In our device, a Kondo pseudospin is realized by two\ndegenerate charge states of a metallic island, which we measure with a\nnon-invasive, capacitively coupled charge sensor. Such pseudospin probe of an\nengineered Kondo system opens the way to the thermodynamic investigation of\nmany exotic quantum states, including the clear observation of Majorana zero\nmodes through their fractional entropy."
    },
    {
        "anchor": "Observation of Weak Localization of Seismic Waves: We report the observation of weak localization of seismic waves in a natural\nenvironment. It emerges as a doubling of the seismic energy around the source\nwithin a spot of width a wavelength, that is several tens of meters in our\ncase. The characteristic time for its onset is the scattering mean free time,\nthat quantifies the internal heterogeneity.",
        "positive": "Gate-Tunable and Thickness-dependent Electronic and Thermoelectric\n  Transport in few-layer MoS2: Over the past few years, there has been a growing interest in layered\ntransition metal dichalcogenides (TMD) such as molybdenum disulfide (MoS2).\nMost studies so far have focused on the electronic and optoelectronic\nproperties of single-layer MoS2, whose band structure features a direct\nbandgap, in sharp contrast to the indirect bandgap of thicker MoS2. In this\npaper, we present a systematic study of the thickness-dependent electrical and\nthermoelectric properties of few-layer MoS2. We observe that the electrical\nconductivity () increases as we reduce the thickness of MoS2 and peaks at about\ntwo layers, with six-time larger conductivity than our thickest sample\n(23-layer MoS2). Using a back-gate voltage, we modulate the Fermi energy () of\nthe sample where an increase in the Seebeck coefficient () is observed with\ndecreasing gate voltage () towards the subthreshold (OFF state) of the device,\nreaching as large as in a four-layer MoS2. While previous reports have focused\non a single-layer MoS2 and measured Seebeck coefficient in the OFF state, which\nhas vanishing electrical conductivity and thermoelectric power factor (), we\nshow that MoS2-based devices in their ON state can have as large as in the\ntwo-layer sample. The increases with decreasing thickness then drops abruptly\nfrom double-layer to single-layer MoS2, a feature we suggest as due to a change\nin the energy dependence of the electron mean-free-path according to our\ntheoretical calculation. Moreover, we show that care must be taken in\nthermoelectric measurements in the OFF state to avoid obtaining erroneously\nlarge Seebeck coefficients when the channel resistance is very high. Our study\npaves the way towards a more comprehensive examination of the thermoelectric\nperformance of two-dimensional (2D) semiconductors."
    },
    {
        "anchor": "Correlated interlayer exciton insulator in double layers of monolayer\n  WSe2 and moir\u00e9 WS2/WSe2: Moir\\'e superlattices in van der Waals heterostructures have emerged as a\npowerful tool for engineering novel quantum phenomena. Here we report the\nobservation of a correlated interlayer exciton insulator in a double-layer\nheterostructure composed of a WSe2 monolayer and a WS2/WSe2 moir\\'e bilayer\nthat are separated by an ultrathin hexagonal boron nitride (hBN). The moir\\'e\nWS2/WSe2 bilayer features a Mott insulator state at hole density p/p0 = 1,\nwhere p0 corresponds to one hole per moir\\'e lattice site. When electrons are\nadded to the Mott insulator in the WS2/WSe2 moir\\'e bilayer and an equal number\nof holes are injected into the WSe2 monolayer, a new interlayer exciton\ninsulator emerges with the holes in the WSe2 monolayer and the electrons in the\ndoped Mott insulator bound together through interlayer Coulomb interactions.\nThe excitonic insulator is stable up to a critical hole density of ~ 0.5p0 in\nthe WSe2 monolayer, beyond which the system becomes metallic. Our study\nhighlights the opportunities for realizing novel quantum phases in double-layer\nmoir\\'e systems due to the interplay between the moir\\'e flat band and strong\ninterlayer electron interactions.",
        "positive": "Optically Induced Nuclear Spin Polarization in the Quantum Hall Regime:\n  The Effect of Electron Spin Polarization through Exciton and Trion\n  Excitations: We study nuclear spin polarization in the quantum Hall regime through the\noptically pumped electron spin polarization in the lowest Landau level. The\nnuclear spin polarization is measured as a nuclear magnetic field $B_N$ by\nmeans of the sensitive resistive detection. We find the dependence of $B_N$ on\nfilling factor unmonotonous. The comprehensive measurements of $B_N$ with the\nhelp of the circularly polarized photoluminescence measurements indicate the\nparticipation of the photo-excited complexes i.e., the exciton and trion\n(charged exciton), in nuclear spin polarization. On the basis of a novel\nestimation method of the equilibrium electron spin polarization, we analyze the\nexperimental data and conclude that the filling factor dependence of $B_N$ is\nunderstood by the effect of electron spin polarization through excitons and\ntrions."
    },
    {
        "anchor": "K-Theory and Pseudospectra for Topological Insulators: We derive formulas and algorithms for Kitaev's invariants in the periodic\ntable for topological insulators and superconductors for finite disordered\nsystems on lattices with boundaries. We find that K-theory arises as an\nobstruction to perturbing approximately compatible observables into compatible\nobservables.\n  We derive formulas in all symmetry classes up to dimension two, and in one\nsymmetry class in dimension three, that can be computed with sparse matrix\nalgorithms. We present algorithms in two symmetry classes in 2D and one in 3D\nand provide illustrative studies regarding how these algorithms can detect the\nscaling properties of phase transitions.",
        "positive": "Kinetics of atomic ordering in metal-doped graphene: Possible stably-ordered substitutional structures based on a graphene-type\ncrystal lattice are considered. A kinetic model of atomic ordering in\nmetal-doped graphene with stoichiometric (1/8, 1/4, 1/2) and nonstoichiometric\ncompositions is developed. Inasmuch as the intrasublattice and intersublattice\n'interchange' ('mixing') energies are competitively different for\ngraphene-based lattice, kinetic curves of the long-range order (LRO) parameters\nmay be nonmonotonic for the structures described by two or three LRO\nparameters."
    },
    {
        "anchor": "Self-Consistent Computation of Spin Torques and Magneto-Resistance in\n  Tunnel Junctions and Magnetic Read-Heads with Metallic Pinhole Defects: A three-dimensional self-consistent spin transport model is developed, which\nincludes both tunnelling transport, as well as metallic transport. Using the\nspin accumulation computed either side of a tunnel barrier, spin torques are\nobtained, and it is shown the model reproduces both damping-like and field-like\nspin-transfer torques, with the expected sinusoidal angular dependence, and\ninverse ferromagnetic layer thickness dependence. An explicit solution to the\ndrift-diffusion model is derived, which allows analysing the effect of both the\nreference and free layer thickness on the spin-transfer torque polarization and\nfield-like coefficient. In particular, when the layers are thin, additional\nspin-dependent scattering contributions due to incomplete absorption of\ntransverse spin components reduce both the damping-like and field-like spin\ntorques. It is shown the model developed here can be used to compute the\nsignal-to-noise ratio in realistic magnetic read-heads, where spin\ntorque-induced fluctuations and instabilities limit the maximum operating\nvoltage. The effect of metallic pinhole defects in the insulator layer is also\nanalysed, which results in a mixture of metallic and tunnelling transport, and\nhighly non-uniform charge and spin currents, requiring the full spin transport\nmodel to compute the resulting magneto-resistance and spin torques. Increasing\nthe area covered by pinholes results in a rapid degradation of the\nmagneto-resistance, following an inverse dependence. Moreover, the spin torque\nangular dependence becomes skewed, and the spin-transfer torque polarization\ndecreases. The same results are obtained when considering tunnel junctions with\na single pinhole defect, but decreasing cross-sectional area, showing that even\na single pinhole defect can significantly degrade the performance of tunnel\njunctions and magnetic read-heads below the 40 nm node.",
        "positive": "Performance of Monolayer Graphene Nanomechanical Resonators with\n  Electrical Readout: The enormous stiffness and low density of graphene make it an ideal material\nfor nanoelectromechanical (NEMS) applications. We demonstrate fabrication and\nelectrical readout of monolayer graphene resonators, and test their response to\nchanges in mass and temperature. The devices show resonances in the MHz range.\nThe strong dependence of the resonant frequency on applied gate voltage can be\nfit to a membrane model, which yields the mass density and built-in strain.\nUpon removal and addition of mass, we observe changes in both the density and\nthe strain, indicating that adsorbates impart tension to the graphene. Upon\ncooling, the frequency increases; the shift rate can be used to measure the\nunusual negative thermal expansion coefficient of graphene. The quality factor\nincreases with decreasing temperature, reaching ~10,000 at 5 K. By establishing\nmany of the basic attributes of monolayer graphene resonators, these studies\nlay the groundwork for applications, including high-sensitivity mass detectors."
    },
    {
        "anchor": "Drude weight, cyclotron resonance, and the Dicke model of graphene\n  cavity QED: The Dicke model of cavity quantum electrodynamics is approximately realized\nin condensed matter when the cyclotron transition of a two-dimensional electron\ngas is nearly resonant with a cavity photon mode. We point out that in the\nstrong coupling limit the Dicke model of cavity cyclotron resonance must be\nsupplemented by a term that is quadratic in the cavity photon field and\nsuppresses the model's transition to a super-radiant state. We develop the\ntheory of graphene cavity cyclotron resonance and show that the quadratic term,\nwhich is absent in graphene's low-energy Dirac model Hamiltonian, is in this\ncase dynamically generated by virtual inter-band transitions.",
        "positive": "Parity anomaly and Landau-level lasing in strained photonic honeycomb\n  lattices: We describe the formation of highly degenerate, Landau-level-like amplified\nstates in a strained photonic honeycomb lattice in which amplification breaks\nthe sublattice symmetry. As a consequence of the parity anomaly, the zeroth\nLandau level is localized on a single sublattice and possesses an enhanced or\nreduced amplification rate. The spectral properties of the higher Landau levels\nare constrained by a generalized time-reversal symmetry. In the setting of\ntwo-dimensional photonic crystal lasers, the anomaly directly affects the mode\nselection and lasing threshold while in three-dimensional photonic lattices it\ncan be probed via beam dynamics."
    },
    {
        "anchor": "Edge-mode velocities and thermal coherence of quantum Hall\n  interferometers: We present comprehensive results on the edge-mode velocities in a quantum\nHall droplet with realistic interaction and confinement at various filling\nfractions. We demonstrate that the charge-mode velocity scales roughly with the\nvalence Landau level filling fraction and the Coulomb energy in the\ncorresponding Landau level. At Landau level filling fraction nu = 5/2, the\nstark difference between the bosonic charge-mode velocity and the fermionic\nneutral-mode velocity can manifest itself in the thermal smearing of the\nnon-Abelian quasiparticle interference. We estimate the dependence of the\ncoherence temperature on the confining potential strength, which may be tunable\nexperimentally to enhance the non-Abelian state.",
        "positive": "Hamiltonian theory of the strongly-coupled limit of the Kondo problem in\n  the overscreened case: By properly generalizing Nozie`res' Fermi liquid theory, we construct an\nHamiltonian approach to the scattering of conduction electrons off a spin-1/2\nimpurity in the ovescreneed Kondo regime, as T -> 0. We derive the S-matrix at\nthe interacting fixed point, and the corresponding phase shifts, together with\nleading energy corrections to the unitary limit. We apply our results to obtain\nthe low-temperature dependence of the 2-channel Kondo conductance, and we\nrelate it to possible transport experiments in a Quantum Dot"
    },
    {
        "anchor": "Spin absorption at ferromagnetic-metal/platinum-oxide interface: We investigate the absorption of a spin current at a\nferromagnetic-metal/Pt-oxide interface by measuring current-induced\nferromagnetic resonance. The spin absorption was characterized by the magnetic\ndamping of the heterostructure. We show that the magnetic damping of a\nNi$_{81}$Fe$_{19}$ film is clearly enhanced by attaching Pt-oxide on the\nNi$_{81}$Fe$_{19}$ film. The damping enhancement is disappeared by inserting an\nultrathin Cu layer between the Ni$_{81}$Fe$_{19}$ and Pt-oxide layers. These\nresults demonstrate an essential role of the direct contact between the\nNi$_{81}$Fe$_{19}$ and Pt-oxide to induce sizable interface spin-orbit\ncoupling. Furthermore, the spin-absorption parameter of the\nNi$_{81}$Fe$_{19}$/Pt-oxide interface is comparable to that of intensively\nstudied heterostructures with strong spin-orbit coupling, such as an oxide\ninterface, topological insulators, metallic junctions with Rashba spin-orbit\ncoupling. This result illustrates strong spin-orbit coupling at the\nferromagnetic-metal/Pt-oxide interface, providing an important piece of\ninformation for quantitative understanding the spin absorption and spin-charge\nconversion at the ferromagnetic-metal/metallic-oxide interface.",
        "positive": "Graphene infrared light emitting diode (GILED): The present Letter proposes a device based on graphene for infrared light\nemission. It is based on a n- and p-doped monolayer graphene (MGs), with Fermi\nenergies $E_F$ and -$E_F$, respectively, sandwiching a bilayer graphene (BG)\nwith bandgap $\\Lambda=2|eV_g-\\Delta|\\geq 2E_F$, where $V_g$ is the gate voltage\nacross the BG and $\\Delta$ the sub-lattice energy difference into each layer of\nthe BG. This device works as simple as tuning the gate voltage to decrease the\nBG bandgap down to $2E_F$; and, once this condition is fulfilled, a current\nflows from the n-doped MG to the p-doped MG. However, when electrons achieve\nthe other side of the device, i.e., into the p-doped MG, their energies ($E_F$)\nare much bigger than the holes energies ($-E_F$), and thus these electrons\ndecay emitting infrared photons."
    },
    {
        "anchor": "High Efficiency Carrier Multiplication in PbSe Nanocrystals:\n  Implications for Solar Energy: We demonstrate for the first time that impact ionization (II) [the inverse of\nAuger recombination (AR)] occurs with very high efficiency in semiconductor\nnanocrystals (NCs). Interband optical excitation of PbSe NCs at low pump\nintensities, for which less than one exciton is initially generated per NC on\naverage, results in the formation of two or more excitons (carrier\nmultiplication) when pump photon energies are more than three times the NC band\ngap energy. Generation of multiexcitons from a single photon absorption event\nis observed to take place on an ultrafast (picosecond) timescale and occurs\nwith up to 100% efficiency depending upon the excess energy of the absorbed\nphoton. Efficient II in NCs can be used to considerably increase the power\nconversion efficiency of NC-based solar cells.",
        "positive": "Generation of energy selective excitations in quantum Hall edge states: We operate an on-demand source of single electrons in high perpendicular\nmagnetic fields up to 30T, corresponding to a filling factor below 1/3. The\ndevice extracts and emits single charges at a tunable energy from and to a\ntwo-dimensional electron gas, brought into well defined integer and fractional\nquantum Hall (QH) states. It can therefore be used for sensitive electrical\ntransport studies, e.g. of excitations and relaxation processes in QH edge\nstates."
    },
    {
        "anchor": "Tuneable superconducting effective gap in graphene-TMDC heterostructures: Growth of graphene on monolayer transition-metal dichalcogenides presents\nopening on band gap and giant spin-orbit coupling which paves the way to\nachieve a useful hybrid structure for electronics and spintronics applications.\nIncrease of the atomic number of transition-metal results in a large SOC, where\neventually a band inversion appears in graphene-$WSe_2$. We consider\nsuperconductor induction by proximity effect to the graphene-TMDC hybrid\nstructure. As a necessity of formalism, we introduce a proper time-reversal and\nparticle-hole symmetry operators, under which the $8 \\times 8$\nDirac-Bogoliubov-de Gennes low-energy effective Hamiltonian is invariant.\nResulting superconducting electron-hole excitations shows that, the essential\ndynamical parameters $\\lambda_I^{A,B}$ and $\\lambda_R$ have significant effect\non superconducting excitations and, specifically, subgap energy. Dependence of\nthe superconducting energy excitation on chemical potential is explored. The\nsignature of spin triplet $p$-wave pairing symmetry in the system is found to\nincrease the subgap superconducting energy, in comparing to $s$-wave symmetry.",
        "positive": "The non-linear terahertz response of hot electrons in low-dimensional\n  semiconductor superlattices: Suppression of the polar-optical phonon\n  scattering: We study the response of low-dimensional semiconductor superlattices to\nstrong terahertz fields on condition of a strong suppression of inelastic\nscattering processes of electrons caused by the polar-optical phonons. For our\nstudy we employ a balance equations approach which allows investigating the\nresponse of the superlattices to strong terahertz fields taking account of both\nthe inelastic and the strongly pronounced elastic scattering of electrons. Our\napproach provides a way to analyze the influence of the Bloch dynamics of\nelectrons in a superlattice miniband side by side with the effects of the\nelectron heating on the magnitude and the frequency dependence of a\nsuperlattice current responsivity in the terahertz frequency band. Our study\nshows that the suppression of the inelastic scattering caused either by a\nreduction of the superlattice dimensionality by lateral quantization or by a\nstrong magnetic field application can give rise to a huge enhancement of the\ncurrent responsivity. This enhancement can be interpreted in terms of the well\npronounced electronic bolometric effect occurring due to the efficient electron\nheating in the low-dimensional superlattices by the incident terahertz fields."
    },
    {
        "anchor": "Parity Effects in Stacked Nanoscopic Quantum Rings: The ground state and the dielectric response of stacked quantum rings are\ninvestigated in the presence of an applied magnetic field along the ring axis.\nFor odd number $N$ of rings and an electric field perpendicular to the axis, a\nlinear Stark effect occurs at distinct values of the magnetic field. At those\nfields energy levels cross in the absence of electric field. For even values of\n$N$ a quadratic Stark effect is expected in all cases, but the induced electric\npolarization is discontinuous at those special magnetic fields. Experimental\nconsequences for related nanostructures are discussed.",
        "positive": "Anyonic interferometry without anyons: How a flux qubit can read out a\n  topological qubit: Proposals to measure non-Abelian anyons in a superconductor by quantum\ninterference of vortices suffer from the predominantly classical dynamics of\nthe normal core of an Abrikosov vortex. We show how to avoid this obstruction\nusing coreless Josephson vortices, for which the quantum dynamics has been\ndemonstrated experimentally. The interferometer is a flux qubit in a Josephson\njunction circuit, which can nondestructively read out a topological qubit\nstored in a pair of anyons --- even though the Josephson vortices themselves\nare not anyons. The flux qubit does not couple to intra-vortex excitations,\nthereby removing the dominant restriction on the operating temperature of\nanyonic interferometry in superconductors."
    },
    {
        "anchor": "Decay of nuclear hyperpolarization in silicon microparticles: We investigate the low-field relaxation of nuclear hyperpolarization in\nundoped and highly doped silicon microparticles at room temperature following\nremoval from high field. For nominally undoped particles, two relaxation time\nscales are identified for ambient fields above 0.2 mT. The slower, T_1s, is\nroughly independent of ambient field; the faster, T_1f, decreases with\nincreasing ambient field. A model in which nuclear spin relaxation occurs at\nthe particle surface via a two-electron mechanism is shown to be in good\nagreement with the experimental data, particularly the field-independence of\nT_1s. For boron-doped particles, a single relaxation time scale is observed.\nThis suggests that for doped particles, mobile carriers and bulk ionized\nacceptor sites, rather than paramagnetic surface states, are the dominant\nrelaxation mechanisms. Relaxation times for the undoped particles are not\naffected by tumbling in a liquid solution.",
        "positive": "Spin orientation by electric current in (110) quantum wells: We develop a theory of spin orientation by electric current in (110)-grown\nsemiconductor quantum wells. The controversy in the factor of two from two\nexisted approaches is resolved by pointing out the importance of energy\nrelaxation in this problem. The limiting cases of fast and slow energy\nrelaxation relative to spin relaxation are considered for asymmetric (110)\nquantum wells. For symmetricly-doped structures the effect of spin orientation\nis shown to exist due to spatial fluctuations of the Rashba spin-orbit\nsplitting. We demonstrate that the spin orientation depends strongly on the\ncorrelation length of these fluctuations as well as on the ratio of the energy\nand spin relaxation rates. The time-resolved kinetics of spin polarization by\nelectric current is also governed by the correlation length being not purely\nexponential at slow energy relaxation. Electrical spin orientation in\ntwo-dimensional topological insulators is calculated and compared with the spin\npolarization induced by the magnetic field."
    },
    {
        "anchor": "Ultra-long relaxation of a Kramers qubit formed in a bilayer graphene\n  quantum dot: The intrinsic valley degree of freedom makes bilayer graphene a unique\nplatform for emerging types of semiconducting qubits. The single-carrier\nquantum dot ground state exhibits a two-fold degeneracy where the two states\nhave opposite spin and valley quantum numbers. By breaking the time-reversal\nsymmetry of this ground state with an out-of-plane magnetic field, a novel type\nof qubit (Kramers qubit), encoded in the two-dimensional spin-valley subspace,\nbecomes accessible. The Kramers qubit is robust against known spin- and\nvalley-mixing mechanisms, as it requires a simultaneous change of both quantum\nnumbers, potentially resulting in long relaxation and coherence times. We\nmeasure the relaxation time of a single carrier in the excited states of a\nbilayer graphene quantum dot at small ($\\sim \\mathrm{mT}$) and zero magnetic\nfields. We demonstrate ultra-long spin-valley relaxation times of the Kramers\nqubit exceeding $30~\\mathrm{s}$, which is about two orders of magnitude longer\nthan the spin relaxation time of $400~\\mathrm{ms}$. The demonstrated\nhigh-fidelity single-shot readout and long relaxation times are the foundation\nfor novel, long-lived semiconductor qubits.",
        "positive": "Quantum Spin Hall and Quantum Anomalous Hall States Realized in Junction\n  Quantum Wells: Both quantum spin Hall and quantum anomalous Hall states are novel states of\nquantum matter with promising applications. We propose junction quantum wells\ncomprising II-VI, III-V or IV semiconductors as a large class of new materials\nrealizing the quantum spin Hall state. Especially, we find that the bulk band\ngap for the quantum spin Hall state can be as large as 0.1 eV. Further more,\nmagnetic doping would induce the ferromagnetism in these junction quantum wells\ndue to band edge singularities in the band-inversion regime and to realize the\nquantum anomalous Hall state."
    },
    {
        "anchor": "Analytic solution of Ando's surface roughness model with finite domain\n  distribution functions: Ando's surface roughness model is applied to metallic nanowires and extended\nbeyond small roughness size and infinite barrier limit approximations for the\nwavefunction overlaps, such as the Prange-Nee approximation. Accurate and fast\nsimulations can still be performed without invoking these overlap\napproximations by averaging over roughness profiles using finite domain\ndistribution functions to obtain an analytic solution for the scattering rates.\nThe simulations indicate that overlap approximations, while predicting a\nresistivity that agrees more or less with our novel approach, poorly estimate\nthe underlying scattering rates. All methods show that a momentum gap between\nleft- and right-moving electrons at the Fermi level, surpassing a critical\nmomentum gap, gives rise to a substantial decrease in resistivity.",
        "positive": "Strong coupling with light enhances the photoisomerization quantum yield\n  of azobenzene: The strong coupling between molecules and photons in resonant cavities offers\na new toolbox to manipulate photochemical reactions. While the quenching of\nphotochemical reactions in the strong coupling regime has been demonstrated\nbefore, their enhancement has proven to be more elusive. By means of a\nstate-of-the-art approach, here we show how the \\iso{trans}{cis}\nphotoisomerization quantum yield of azobenzene embedded in a realistic\nenvironment can be higher in polaritonic conditions than in the cavity-free\ncase. We characterize the mechanism leading to such enhancement and discuss the\nconditions to push the photostationary state towards the unfavoured reaction\nproduct. Our results provide a signature that the control of photochemical\nreactions through strong coupling can be extended from selective quenching to\nimprovement of the quantum yields"
    },
    {
        "anchor": "Localized magnetic states in biased bilayer and trilayer graphene: We study the localized magnetic states of impurity in biased bilayer and\ntrilayer graphene. It is found that the magnetic boundary for bilayer and\ntrilayer graphene presents the mixing features of Dirac and conventional\nfermion. For zero gate bias, as the impurity energy approaches the Dirac point,\nthe impurity magnetization region diminishes for bilayer and trilayer graphene.\nWhen a gate bias is applied, the dependence of impurity magnetic states on the\nimpurity energy exhibits a different behavior for bilayer and trilayer graphene\ndue to the opening of a gap between the valence and the conduction band in the\nbilayer graphene with the gate bias applied. The magnetic moment and the\ncorresponding magnetic transition of the impurity in bilayer graphene are also\ninvestigated.",
        "positive": "Engineering Exchange Coupling in Double Elliptic Quantum Dots: Coupled elliptic quantum dots with different aspect ratios containing up to\ntwo electrons are studied using a model confinement potential in the presence\nof magnetic fields. Single and two particle Schroedinger equations are solved\nusing numerical exact diagonolization to obtain the exchange energy and\nchemical potentials. As the ratio between the confinement strengths in\ndirections perpendicular and parallel to the coupling direction of the double\ndots increases, the exchange energy at zero magnetic field increases, while the\nmagnetic field of the singlet-triplet transition decreases. By investigating\nthe charge stability diagram, we find that as inter-dot detuning increases, the\nabsolute value of the exchange energy increases superlinearly followed by\nsaturation. This behavior is attributed to the electron density differences\nbetween the singlet and triplet states in the assymetric quantum dot systems."
    },
    {
        "anchor": "Transversal electric field effect in multilayer graphene nanoribbon: We study the effect of transversal electric-field (E-field) on the electronic\nproperties of multilayer armchair-graphene-nanoribbon (AGNR). The bandgap in\nmultilayer-AGNRs can be reversibly modulated with the application of E-field.\nAt optimized widths, we obtain a semiconductor (SC) to metallic (M), as well as\nM-SC transition. The AGNR electronic bands undergo vivid transformations due to\nthe E-field, leading to phenomena such as increase in electron velocity, change\nin the sign of the electron effective mass, and the formation of linear\ndispersion with massless Dirac fermions similar to 2D-graphene. These effects\nare very useful and can be utilized for device applications.",
        "positive": "Magnetic field oscillations of the critical current in long ballistic\n  graphene Josephson junctions: We study the Josephson current in long ballistic superconductor-monolayer\ngraphene-superconductor junctions. As a first step, we have developed an\nefficient computational approach to calculate the Josephson current in\ntight-binding systems. This approach can be particularly useful in the long\njunction limit, which has hitherto attracted less theoretical interest but has\nrecently become experimentally relevant. We use this computational approach to\nstudy the dependence of the critical current on the junction geometry, doping\nlevel, and an applied perpendicular magnetic field. In zero magnetic field we\nfind a good qualitative agreement with the recent experiment of Ben Shalom et\nal. (Reference[12]) for the length dependence of the critical current. For\nhighly doped samples our numerical calculations show a broad agreement with the\nresults of the quasiclassical formalism. In this case the critical current\nexhibits Fraunhofer-like oscillations as a function of the magnetic field.\nHowever, for lower doping levels, where the cyclotron orbit becomes comparable\nto the characteristic geometrical length scales of the system, deviations from\nthe results of the quasiclassical formalism appear. We argue that due to the\nexceptional tunability and long mean free path of graphene systems a new regime\ncan be explored where geometrical and dynamical effects are equally important\nto understand the magnetic field dependence of the critical current."
    },
    {
        "anchor": "Spin relaxation of a diffusively moving carrier in a random hyperfine\n  field: Relaxation, <Sz(t)>, of the average spin of a carrier in course of hops over\nsites hosting random hyperfine fields is studied theoretically. In low\ndimensions, d = 1, 2, the decay of average spin with time is non-exponential at\nall times. The origin of the effect is that for d = 1, 2 a typical random-walk\ntrajectory exhibits numerous self-intersections. Multiple visits of the carrier\nto the same site accelerates the relaxation since the corresponding partial\nrotations of spin during these visits add up. Another consequence of\nself-intersections of the random-walk trajectories is that, in all dimensions,\nthe average, <Sz(t)>, becomes sensitive to a weak magnetic field directed along\nz. Our analytical predictions are complemented by the numerical simulations of\n<Sz(t)>.",
        "positive": "Topological Zak Phase in Strongly-Coupled LC Circuits: We show the emergence of topological Bogoliubov bosonic excitations in the\nrelatively strong coupling limit of an LC (inductance-capacitance)\none-dimensional quantum circuit. This dimerized chain model reveals a ${\\cal\nZ}_2$ local symmetry as a result of the counter-rotating wave (pairing) terms.\nThe topology is protected by the sub-lattice symmetry, represented by an\nanti-unitary transformation. We present a methos to measure the winding of the\ntopological Zak phase across the Brillouin zone by a reflection measurement of\n(microwave) light. Our method probes bulk quantities and can be implemented\neven in small systems. We study the robustness of edge modes towards disorder."
    },
    {
        "anchor": "Universal topological quench dynamics: Altland-Zirnbauer tenfold classes: Topological phases of the famous Altland-Zirnbauer (AZ) tenfold classes are\ndefined on the equilibrium ground states. Whether such equilibrium topological\nphases have universal correspondence to far-from-equilibrium quantum dynamics\nis a fundamental issue of both theoretical and experimental importance. Here we\nuncover the universal topological quench dynamics linking to the equilibrium\ntopological phases for the complete AZ tenfold classes, with a general\nframework being established. We show a fundamental result that a\n$d$-dimensional topological phase of the tenfold class, with an integer\ninvariant or $\\mathbb{Z}_{2}$ index defined on high symmetry momenta, is\ngenerically characterized by topology reduced to the highest-order\nband-inversion surfaces located at arbitrary discrete momenta of Brillouin\nzone. Such dimension-reduced topology is further captured by universal\ntopological patterns emerging in far-from-equilibrium quantum dynamics by\nquenching the system from trivial phase to the topological regime, rendering\nthe dynamical hallmark of the equilibrium topological phase. This work\nestablishes a universal dynamical characterization for the complete AZ symmetry\nclasses of topological phases, which has broad applications in theory and\nexperiment.",
        "positive": "Kelvin-Mach wake in a two-dimensional Fermi sea: The dispersion law for plasma oscillations in a two-dimensional electron gas\nin the hydrodynamic approximation interpolates between $\\Omega \\propto\n\\sqrt{q}$ and $\\Omega \\propto q$ dependences as the wave vector $q$ increases.\nAs a result, downstream of a charged impurity in the presence of a uniform\nsupersonic electric current flow, a wake pattern of induced charge density and\npotential is formed whose geometry is controlled by the Mach number $M$. For\n$1<M\\leqslant \\sqrt{2}$ the wake consists of transverse wavefronts confined\nwithin a sector whose angle is given by the classic Mach condition. An\nadditional wake of larger angle resembling the Kelvin ship wake and consistsing\nof both transverse and diverging wavefronts is found outside the Mach sector\nfor $M>\\sqrt{2}$. These wakes also trail an external charge traveling\nsupersonically a fixed distance away from the electron gas."
    },
    {
        "anchor": "Deformed Fermi Surface Theory of Magneto-Acoustic Anomaly in Modulated\n  Quantum Hall Systems Near $/nu=1/2$: We introduce a new generic model of a deformed Composite Fermion-Fermi\nSurface (CF-FS) for the Fractional Quantum Hall Effect near $/nu=1/2$ in the\npresence of a periodic density modulation. Our model permits us to explain\nrecent Surface Acoustic Wave observations of anisotropic anomalies [1,2] in\nsound velocity and attenuation- appearance of peaks and anisotropy - which\noriginate from contributions to the conductivity tensor due to regions of the\nCF-FS which are flattened by the applied modulation. The calculated magnetic\nfield and wave vector dependence of the CF conductivity,velocity shift and\nattenuation agree with experiments.",
        "positive": "Area-Delay-Energy Tradeoffs of Strain-Mediated Multiferroic Devices: Multiferroic devices hold profound promise for ultra-low energy computing in\nbeyond Moore's law era. The magnetization of a magnetostrictive\nshape-anisotropic single-domain nanomagnet strain-coupled with a piezoelectric\nlayer in a multiferroic composite structure can be switched between its two\nstable states (separated by an energy barrier) with a tiny amount of voltage\nvia converse magnetoelectric effect. With appropriate choice of materials, the\nmagnetization can be switched with a few tens of millivolts of voltages in\nsub-nanosecond switching delay while spending a miniscule amount of energy of\n~1 attojoule at room-temperature. Here, we analyze the area-delay-energy\ntrade-offs of these multiferroic devices by solving stochastic\nLandau-Lifshitz-Gilbert equation in the presence of room-temperature thermal\nfluctuations. We particularly put attention on scaling down the lateral area of\nthe magnetostrictive nanomagnet that can increase the device density on a chip.\nWe show that the vertical thickness of the nanomagnet can be increased while\nscaling down the lateral area and keeping the assumption of single-domain limit\nvalid. This has important consequence since it helps to some extent preventing\nthe deterioration of the induced stress-anisotropy energy in the\nmagnetostrictive nanomagnet, which is proportional to the nanomagnet's volume.\nThe results show that if we scale down the lateral area, the switching delay\nincreases while energy dissipation decreases. Avenues available to decrease the\nswitching delay while still reducing the energy dissipation are discussed."
    },
    {
        "anchor": "Effect of magnetic field on the electronic properties of an\n  $\u03b1$-$T_3$ ring: We consider a quantum ring of a certain radius R built from a sheet of the\n$\\alpha$-$T_3$ lattice and solve for its spectral properties in presence of an\nexternal magnetic field. The energy spectrum consists of a conduction band, a\nvalence band and a zero energy flat band, all having a number of discrete\nlevels therein which can be characterized by the angular momentum quantum\nnumber, m. The energy levels in the flat band are infinitely degenerate\nirrespective of the value of $\\alpha$. We reveal a two-fold degeneracy of the\nlevels in the conduction band as well as in the valence band for $\\alpha$ = 0\nand $\\alpha$ = 1. However, the m = 0 level for $\\alpha$ = 1 is an exception.\nCorresponding to an intermediate value of $\\alpha$, namely, 0 <$\\alpha$< 1, the\nenergy levels become nondegenerate. The scenario remains unaltered when the\nring is threaded by a magnetic flux which is an integer multiple of the flux\nquantum. We also calculate the persistent current which exhibits quantum\noscillations as a function of the magnetic field with a period of one flux\nquantum at a particular Dirac point, which is often referred to as a valley.\nThe total current oscillates with a periodicity of one flux quantum for any\nintermediate value of $\\alpha$. We have also explored the effect of a mass term\n(that breaks the sublattice symmetry) in the Hamiltonian. In the absence of a\nmagnetic field, the energy levels in the flat band become dispersive, except\nfor the m = 0 level in the case of $\\alpha$ = 1. In presence of the field, each\nof the flat band levels becomes dispersive for any $\\alpha \\neq$ 0. Finally, we\nalso see the effect of the mass term on the behaviour of the persistent\ncurrent, which shows periodicity of one flux quantum, but the total current\nremains finite for all values of $\\alpha$.",
        "positive": "Near-field heat transfer between a nanoparticle and a rough surface: In this work we focus on the surface roughness correction to the near-field\nradiative heat transfer between a nanoparticle and a material with a rough\nsurface utilizing a direct perturbation theory up to second order in the\nsurface profile. We discuss the different distance regimes for the local\ndensity of states above the rough material and the heat flux analytically and\nnumerically. We show that the heat transfer rate is larger than that\ncorresponding to a flat surface at short distances. At larger distances it can\nbecome smaller due to surface polariton scattering by the rough surface. For\ndistances much smaller than the correlation length of the surface profile, we\nshow that the results converge to a proximity approximation, whereas in the\nopposite limit the rough surface can be replaced by an equivalent surface\nlayer."
    },
    {
        "anchor": "Imaging Inter-Edge State Scattering Centers in the Quantum Hall Regime: We use an atomic force microscope tip as a local gate to study the scattering\nbetween edge channels in a 2D electron gas in the quantum Hall regime. The\nscattering is dominated by individual, microscopic scattering centers, which we\ndirectly image here for the first time. The tip voltage dependence of the\nscattering indicates that tunneling occurs through weak links and localized\nstates.",
        "positive": "Nonadiabatic transitions between adiabatic surfaces: phase diffusion in\n  superconducting atomic point contacts: Motivated by experiments with current biased superconducting atomic point\ncontacts the general problem of nonadiabatic transitions between adiabatic\nsurfaces in presence of strong dissipation is studied. For a single channel\ndevice the supercurrent is determined by the diffusive motion of the\nsuperconducting phase difference on two Andreev levels. These surfaces are\nuncoupled only in the adiabatic limit of low to moderate transmissions, while\nfor high transmissions curve crossings are important. Starting from a general\nmaster equation of the full density matrix an approximate time evolution\nequation for the populations on the adiabatic surfaces in the overdamped limit\nis derived from which the relevant observables can be obtained. Specific\nresults for the case of atomic point contacts are in agreement with\nexperimental observations that cannot be explained by conventional theory."
    },
    {
        "anchor": "Wave attenuation to clock sojourn times: The subject of time in quantum mechanics is of perennial interest especially\nbecause there is no observable for the time taken by a particle to transmit (or\nreflect) from a particular region. Several methods have been proposed based on\nscattering phase shifts and using different quantum clocks, where the time\ntaken is clocked by some external input or indirectly from the phase of the\nscattering amplitudes. In this work we give a general method for calculating\nconditional sojourn times based on wave attenuation. In this approach clock\nmechanism does not couple to the Hamiltonian of the system. For simplicity,\nspecific case of a delta dimer is considered in detail. Our analysis re-affirms\nrecent results based on correcting quantum clocks using optical potential\nmethods, albeit in a much simpler way.",
        "positive": "Quantum Coherent Multielectron Processes in an Atomic Scale Contact: The light emission from a scanning tunneling microscope operated on a Ag(111)\nsurface at 6 K is analyzed from low conductances to values approaching the\nconductance quantum. Optical spectra recorded at a sample voltages V reveal\nemission with photon energies hv> 2eV. A model of electrons interacting\ncoherently via a localized plasmon-polariton mode reproduces the experimental\ndata, in particular the kinks in the spectra at eV and 2eV as well as the\nscaling of the intensity at low and intermediate conductances."
    },
    {
        "anchor": "Transport theory in non-Hermitian systems: Non-Hermitian systems have garnered significant attention due to the\nemergence of novel topology of complex spectra and skin modes. However,\ninvestigating transport phenomena in such systems faces obstacles stemming from\nthe non-unitary nature of time evolution. Here, we establish the continuity\nequation for a general non-Hermitian Hamiltonian in the Schr\\\"odinger picture.\nIt attributes the universal non-conservativity to the anti-commutation\nrelationship between particle number and non-Hermitian terms. Our work derives\na comprehensive current formula for non-Hermitian systems using Green's\nfunction, applicable to both time-dependent and steady-state responses. To\ndemonstrate the validity of our approach, we calculate the local current in\nmodels with one-dimensional and two-dimensional settings, incorporating\nscattering potentials. The spatial distribution of local current highlights the\nwidespread non-Hermitian phenomena, including skin modes, non-reciprocal\nquantum dots, and corner states. Our findings offer valuable insights for\nadvancing theoretical and experimental research in the transport of\nnon-Hermitian systems.",
        "positive": "Superconducting and Insulating Behavior in One-Dimensional Josephson\n  Junction Arrays: Experiments on one-dimensional small capacitance Josephson Junction arrays\nare described. The arrays have a junction capacitance that is much larger than\nthe stray capacitance of the electrodes, which we argue is important for\nobservation of Coulomb blockade. The Josephson energy can be tuned in situ and\nan evolution from Josephson-like to Coulomb blockade behavior is observed. This\nevolution can be described as a superconducting to insulating, quantum phase\ntransition. In the Coulomb blockade state, hysteretic current-voltage\ncharacteristics are described by a dynamic model which is dual to the\nresistively shunted junction model of classical Josephson junctions."
    },
    {
        "anchor": "Programmable quantum Hall bisector: towards a novel resistance standard\n  for quantum metrology: We demonstrate a programmable quantum Hall circuit that implements a novel\niterative voltage bisection scheme and allows obtaining any binary fraction\n$(k/2^n)$ of the fundamental resistance quantum $R_K/2=h/2e^2$. The circuit\nrequires a number $n$ of bisection stages that only scales logarithmically with\nthe precision of the fraction. The value of $k$ can be set to any integer\nbetween 1 and $2^n$ by proper gate configuration. The architecture exploits\ngate-controlled routing, mixing and equilibration of edge modes of robust\nquantum Hall states. The device does not contain {\\em any} internal ohmic\ncontact potentially leading to spurious voltage drops. Our scheme addresses key\ncritical aspects of quantum Hall arrays of resistance standards, which are\ntoday widely studied and used to create custom calibration resistances. The\napproach is demonstrated in a proof-of-principle two-stage bisection circuit\nbuilt on a high-mobility GaAs/AlGaAs heterostructure operating at a temperature\nof $260\\,{\\rm mK}$ and a magnetic field of $4.1\\,{\\rm T}$.",
        "positive": "Level Curvatures and Conductances: A Numerical Study of the Thouless\n  Relation: The Thouless conjecture states that the average conductance of a disordered\nmetallic sample in the diffusive regime can be related to the sensitivity of\nthe sample's spectrum to a change in the boundary conditions. Here we present\nresults of a direct numerical study of the conjecture for the Anderson model.\nThey were obtained by calculating the Landauer-B\\\"uttiker conductance $g_L$ for\na sample connected to perfect leads and the distribution of level curvatures\nfor the same sample in an isolated ring geometry, when the ring is pierced by\nan Aharonov-Bohm flux. In the diffusive regime ($L\\gg l_e$) the average\nconductance $g_L$ is proportional to the mean absolute curvature $< |c| >$: $\ng_L = \\pi <| c | > / \\Delta$, provided the system size $L$ is large enough, so\nthat the contact resistance can be neglected. $l_e$ is the elastic mean free\npath, $\\Delta$ is the mean level spacing. When approaching the ballistic\nregime, the limitation of the conductance due to the contact resistance becomes\nessential and expresses itself in a deviation from the above proportionality.\nHowever, in both regimes and for all system sizes the same proportionality is\nrecovered when the contact resistance is subtracted from the inverse\nconductance, showing that the ``curvatures measure the conductance in the\nbulk''. In the localized regime, the mean logarithm of the absolute curvature\nand the mean logarithm of the Landauer-B\\\"uttiker conductance are proportional."
    },
    {
        "anchor": "Hard-gap spectroscopy in a self-defined mesoscopic InAs/Al nanowire\n  Josephson junction: Superconductor/semiconductor-nanowire hybrid structures can serve as\nversatile building blocks to realize Majorana circuits or superconducting\nqubits based on quantized levels such as Andreev qubits. For all these\napplications it is essential that the superconductor-semiconductor interface is\nas clean as possible. Furthermore, the shape and dimensions of the\nsuperconducting electrodes needs to be precisely controlled. We fabricated\nself-defined InAs/Al core/shell nanowire junctions by a fully in-situ approach,\nwhich meet all these criteria. Transmission electron microscopy measurements\nconfirm the sharp and clean interface between the nanowire and the in-situ\ndeposited Al electrodes which were formed by means of shadow evaporation.\nFurthermore, we report on tunnel spectroscopy, gate and magnetic\nfield-dependent transport measurements. The achievable short junction\nlengths,the observed hard-gap and the magnetic field robustness make this new\nhybrid structure very attractive for applications which rely on a precise\ncontrol of the number of sub-gap states, like Andreev qubits or topological\nsystems.",
        "positive": "Tunable magnetoresistance in spin-orbit coupled graphene junctions: Using the Landauer-B\\\"utikker formalism, we study the graphene\nmagneto-transport in the presence of Rashba spin-orbit interaction (RSOI). We\nshow that the angle resolved transmission probability in the proposed\nstructures can be tuned by the RSOI strength. The transmission spectrum show\nKlein tunneling in the parallel (P) magnetization configuration which can be\nblocked by the RSOI. This effect is also observable for the anti-parallel (AP)\nmagnetization configuration in different incident angle. The numerical results\nshows that the spin-polarized conductance strongly depends on the strength of\nthe RSOI and can be generated by tuning the magnetic exchange field and RSOI\nstrength. This spin-polarized conductance is a sensitive oscillatory function\nof the thickness of the RSO region. Because of the spin-flip effect, the\njunction shows a spin-valve effect with large and negative magnetoresistance\n(MR) and spin-magnetoresistance (SMR) in the presence of RSOI. When the RSOI is\non, the frequency and amplitude of shot-noise and Fano factor's oscillations\nare also increased. These results can provide a way to extending the\napplication of graphene-based junctions in spintronics."
    },
    {
        "anchor": "Drag on Cylinders Moving in Superfluid 3He-B as the Dimension Spans the\n  Coherence Length: Vibrating probes when immersed in a fluid can provide powerful tools for\ncharacterising the surrounding medium. In superfluid 3He-B, a condensate of\nCooper pairs, the dissipation arising from the scattering of quasiparticle\nexcitations from a mechanical oscillator provides the basis of extremely\nsensitive thermometry and bolometry at sub-millikelvin temperatures. The unique\nproperties of the Andreev reflection process in this condensate also assist by\nproviding a significantly enhanced dissipation. While existing models for such\ndamping on an oscillating cylinder have been verified experimentally, they are\nvalid only for flows with scales much greater than the coherence length of 3He,\nwhich is of the order of a hundred nanometres. With our increasing proficiency\nin fabricating nanosized oscillators which can be readily used in this\nsuperfluid there is a pressing need for the development of new models that\naccount for the modification of the flow around these smaller oscillators. Here\nwe report preliminary results on measurements of the damping in superfluid\n3He-B of a range of cylindrical nano-sized oscillators with radii comparable to\nthe coherence length, and outline a model for calculating the associated drag.",
        "positive": "Efficient algorithm for current spectral density calculation in\n  single-electron tunneling and hopping: This write-up describes an efficient numerical method for the Monte Carlo\ncalculation of the spectral density of current in the multi-junction\nsingle-electron devices and hopping structures. In future we plan to expand\nthis write-up into a full-size paper."
    },
    {
        "anchor": "Temporal evolution of resonant transmission under telegraph noise: The environment of a quantum dot, which is connected to two leads, is modeled\nby telegraph noise, i.e. random Markovian jumps of the (spinless) electron\nenergy on the dot between two levels. The temporal evolutions of the charge on\nthe dot and of the currents in the leads are studied using a recently developed\nsingle-particle basis approach, which is particularly convenient for the\naveraging over the histories of the noise. In the steady state limit we recover\nthe Landauer formula. At a very fast jump rate between the two levels, the\nnoise does not affect the transport. As the jump rate decreases, the effective\naverage transmission crosses over from the transmission through a single\n(average) level to an incoherent sum of the transmissions through the two\nlevels. 13 pages, 6 figuresThe transient temporal evolution towards the steady\nstate is dominated by the displacement current at short times, and by the\nLandauer current at long times. It contains oscillating terms, which decay to\nzero faster than for the case without noise. When the average chemical\npotential on the leads equals the dot's \"original\" energy, without the noise,\nthe oscillations disappear completely and the transient evolution becomes\nindependent of the noise.",
        "positive": "A comparative computational study of the electronic properties of planar\n  and buckled silicene: Using full potential density functional calculations within local density\napproximation (LDA), we report our investigation of the structural electronic\nproperties of silicene (the graphene analogue of silicon), the strips of which\nhas been synthesized recently on Ag(110) and Ag(100) surfaces. An assumed\nplanar and an optimized buckled two dimensional (2D) hexagonal structures have\nbeen considered for comparisons of their electronic properties. Planar silicene\nshows a gapless band structure analogous to the band structure of graphene with\ncharge carriers behaving like mass-less Dirac fermions, while the structurally\noptimized buckled silicene shows a small direct energy band gap of about 25 meV\n(at the K point of the hexagonal Brillouin zone) in its electronic structure\nand the charge carriers in this case behave like massive Dirac fermions. The\nactual band gap would be larger than this as LDA is known to underestimate the\ngap. The average Fermi velocity of the Dirac fermions in silicene was estimated\nat about half the value experimentally measured in graphene. These properties\nof silicene are attractive for some of the applications one envisages for\ngraphene. Our finding of a direct band gap in silicene is something new. The\nresults, if verified by experiments, are expected to have huge industrial\nimpact in the silicon-based nano-electronics and nano-optics because of the\npossible compatibility silicene with current silicon-based micro-/nano\ntechnology."
    },
    {
        "anchor": "Unoccupied topological surface state in Bi$_{2}$Te$_{2}$Se: Bias voltage dependent scattering of the topological surface state is studied\nby scanning tunneling microscopy/spectroscopy for a clean surface of the\ntopological insulator Bi$_2$Te$_2$Se. A strong warping of constant energy\ncontours in the unoccupied part of the spectrum is found to lead to a\nspin-selective scattering. The topological surface state persists to higher\nenergies in the unoccupied range far beyond the Dirac point, where it coexists\nwith the bulk conduction band. This finding sheds light on the spin and charge\ndynamics over the wide energy range and opens a way to designing\nopto-spintronic devices.",
        "positive": "Novel Electron-Phonon Relaxation Pathway in Graphite Revealed by\n  Time-Resolved Raman Scattering and Angle-Resolved Photoemission Spectroscopy: Time dynamics of photoexcited electron-hole pairs is important for a number\nof technologies, in particular solar cells. We combined ultrafast pump-probe\nRaman scattering and photoemission to directly follow electron-hole excitations\nas well as the G-phonon in graphite after an excitation by an intense laser\npulse. This phonon is known to couple relatively strongly to electrons.\nCross-correlating effective electronic and phonon temperatures places new\nconstraints on model-based fits. The accepted two-temperature model predicts\nthat G-phonon population should start to increase as soon as excited\nelectron-hole pairs are created and that the rate of increase should not depend\nstrongly on the pump fluence. Instead we found that the increase of the\nG-phonon population occurs with a delay of $\\sim$65 fs. This time-delay is also\nevidenced by the absence of the so-called self-pumping for G phonons. It\ndecreases with increased pump fluence. We show that these observations imply a\nnew relaxation pathway: Instead of hot carriers transferring energy to\nG-phonons directly, the energy is first transferred to optical phonons near the\nzone boundary K-points, which then decay into G-phonons via phonon-phonon\nscattering. Our work demonstrates that phonon-phonon interactions must be\nincluded in any calculations of hot carrier relaxation in optical absorbers\neven when only short timescales are considered."
    },
    {
        "anchor": "Strongly-coupled nanotube electromechanical resonators: Coupling an electromechanical resonator with carbon-nanotube quantum dots is\na significant method to control both the electronic charge and the spin quantum\nstates. By exploiting a novel micro-transfer technique, we fabricate two\nstrongly-coupled and electrically-tunable mechanical resonators on a single\ncarbon nanotube for the first time. The frequency of the two resonators can be\nindividually tuned by the bottom gates, and strong coupling is observed between\nthe electron charge and phonon modes of each resonator. Furthermore, the\nconductance of either resonator can be nonlocally modulated by the phonon modes\nin the other resonator. Strong coupling is observed between the phonon modes of\nthe two resonators, which provides an effective long distance electron-electron\ninteraction. The generation of phonon-mediated-spin entanglement is also\ntheoretically analyzed for the two resonators. This strongly-coupled nanotube\nelectromechanical resonator array provides an experimental platform for future\nstudies of the coherent electron-phonon interaction, the phonon mediated\nlong-distance electron interaction, and entanglement state generation.",
        "positive": "Orbital hall effect: from intrinsic mechanism to experimental evidence: Comparing with the spin of electron, the electronic orbitals, which have been\nlong ignored in non-equilibrium transport, are getting more and more\nattentions, due to the prediction and experimental verification of orbital Hall\neffect (OHE) recently. In this report, the recent advances, including intrinsic\nmechanisms, direct and indirect experimental observations of OHE, are reviewed\ncomprehensively. The orbital current, generated by OHE, shows much more\nfundamental features than spin current in explaining Hall conductivity and\nmanipulating magnetization electronically. Theoretically, in momentum space,\nthe OHE is proposed to originate from electric-field driven non-equilibrium\norbital texture, based on tight-binding model. However, current experimental\nworks still stay on the level to reveal how the OHE behaves after orbital\ncurrent is generated, and the unambiguous experimental evidence to verify the\ngeneration mechanism of OHE is still missing, limiting the interpretation of\nOHE. Angle-resolved photoemission spectroscopy with polarized incident photon,\non the other hand, could be used to identify the orbital textures on energy\nband and reveal the non-equilibrium nature of orbital-momentum locking behind\nOHE, which may help to provide the direct experimental evidence to examine the\nintrinsic mechanism of OHE, and reveal the nature of wave packet with\nnon-vanishing orbital angular momentum."
    },
    {
        "anchor": "Anisotropic Moir\u00e9 Optical Transitions in Twisted Monolayer/bilayer\n  Phosphorene Heterostructures: Moir\\'e superlattices of van der Waals heterostructures provide a powerful\nnew way to engineer the electronic structures of two-dimensional (2D)\nmaterials. Many novel quantum phenomena have emerged in different moir\\'e\nheterostructures, such as correlated insulators, superconductors, and Chern\ninsulators in graphene systems and moir\\'e excitons in transition metal\ndichalcogenide (TMDC) systems. Twisted phosphorene offers another attractive\nsystem to explore moir\\'e physics because phosphorene features an anisotropic\nrectangular lattice, different from the isotropic hexagonal lattice in graphene\nand TMDC. Here we report emerging anisotropic moir\\'e optical transitions in\ntwisted monolayer/bilayer phosphorene. The optical resonances in phosphorene\nmoir\\'e superlattice depend sensitively on the twist angle between the\nmonolayer and bilayer. Surprisingly, even for a twist angle as large as\n19{\\deg} the moir\\'e heterostructure exhibits optical resonances completely\ndifferent from those in the constituent monolayer and bilayer phosphorene. The\nnew moir\\'e optical resonances exhibit strong linear polarization, with the\nprincipal axis lying close to but different from the optical axis of bilayer\nphosphorene. Our ab initio calculations reveal that the {\\Gamma}-point direct\nbandgap and the rectangular lattice of phosphorene, unlike the K-point bandgap\nof hexagonal lattice in graphene and TMDC, give rise to the remarkably strong\nmoir\\'e physics in large-twist-angle phosphorene heterostructures. Our results\nhighlight the exciting opportunities to explore moir\\'e physics in phosphorene\nand other van der Waals heterostructures with different lattice configurations.",
        "positive": "Hybrid metal-dielectric nanocavity for enhanced light-matter\n  interactions: Despite tremendous advances in the fundamentals and applications of cavity\nquantum electrodynamics (CQED), investigations in this field have primarily\nbeen limited to optical cavities composed of purely dielectric materials. Here,\nwe demonstrate a hybrid metal-dielectric nanocavity design and realize it in\nthe InAs/GaAs quantum photonics platform utilizing angled rotational metal\nevaporation. Key features of our nanometallic light-matter interface include:\n(i) order of magnitude reduction in mode volume compared to that of leading\nphotonic crystal CQED systems; (ii) surface-emitting nanoscale cylindrical\ngeometry and therefore good collection efficiency; and finally (iii) strong and\nbroadband spontaneous emission rate enhancement (Purcell factor ~ 8) of single\nphotons. This light-matter interface may play an important role in quantum\ntechnologies."
    },
    {
        "anchor": "Uniformity of the pseudomagnetic field in strained graphene: We present a study on the uniformity of the pseudomagnetic field in graphene\nas a function of the relative orientation between the graphene lattice and\nstraining directions. For this, we strained a regular micron-sized graphene\nhexagon by deforming it symmetrically by displacing three of its edges. By\nsimulations, we found that the pseudomagnetic field is strongest if the strain\nis applied perpendicular to the armchair direction of graphene. For a hexagon\nwith a side length of 1 ${\\rm \\mu}$m, the pseudomagnetic field has a maximum of\n1.2 T for an applied strain of 3.5% and it is uniform (variance $< 1$%) within\na circle with a diameter of $\\sim 520$ nm. This diameter is on the order of the\ntypical diameter of the laser spot in a state-of-the-art confocal Raman\nspectroscopy setup, which suggests that observing the pseudomagnetic field in\nmeasurements of shifted magneto-phonon resonance is feasible.",
        "positive": "Activated Layered Magnetism from Bulk TiN: The novel properties of a uniaxially-expanded TiN bulk arising from\nincreasing the layer spacing from equilibrium are explored using a\nfirst-principles approach. We reveal a novel nonmagnetic-magnetic transition\nfrom a TiN bulk to its monolayer. We also investigate the electronic and\nmagnetic structures of a few TiN atomic layers. We find that the bilayer and\ntrilayer, like the TiN bulk, are nonmagnetic poor metals. On the other hand,\nthe monolayer TiN is found to carry a magnetic moment on its Ti atoms, and\nlikely be a semiconductor. The unpaired electron giving rise to magnetism on Ti\nis primarily in the orbital perpendicular to the layers, and we find it is\nfreed to give rise to magnetism when the layers are slightly separated. We find\ntwo different antiferromagnetic states possible on the monolayer, as well as\none ferromagnetic, with one of the antiferromagnetic being the lowest energy.\nThe exchange couplings between Ti atoms in such a monolayer are calculated to\nbe antiferromagnetic for both the nearest-neighbor and next-nearest-neighbor\nsites. We also analyze the binding nature of both the monolayer and bilayer TiN\nby searching for the predominant binding orbitals."
    },
    {
        "anchor": "Second Euler number in four dimensional synthetic matter: Two-dimensional Euler insulators are novel kind of systems that host\nmulti-gap topological phases, quantified by a quantised first Euler number in\ntheir bulk. Recently, these phases have been experimentally realised in\nsuitable two-dimensional synthetic matter setups. Here we introduce the second\nEuler invariant, a familiar invariant in both differential topology\n(Chern-Gauss-Bonnet theorem) and in four-dimensional Euclidean gravity, whose\nexistence has not been explored in condensed matter systems. Specifically, we\nfirstly define two specific novel models in four dimensions that support a\nnon-zero second Euler number in the bulk together with peculiar gapless\nboundary states. Secondly, we discuss its robustness in general\nspacetime-inversion invariant phases and its role in the classification of\ntopological degenerate real bands through real Grassmannians. In particular, we\nderive from homotopy arguments the minimal Bloch Hamiltonian form from which\nthe tight-binding models of any second Euler phase can be generated.\nConsidering more concretely the gapped Euler phase associated with the tangent\nbundle of the four-sphere, we show that the bulk band structure of the\nnontrivial 4D Euler phase necessarily exhibits triplets of linked nodal\nsurfaces (where the three types of nodal surfaces are formed by the crossing of\nthe three successive pairs of bands within one four-band subspace). Finally, we\nshow how to engineer these new topological phases in a four-dimensional\nultracold atom setup. Our results naturally generalize the second Chern and\nspin Chern numbers to the case of four-dimensional phases that are\ncharacterised by real Hamiltonians and open doors for implementing such\nunexplored higher-dimensional phases in artificial engineered systems, ranging\nfrom ultracold atoms to photonics and electric circuits.",
        "positive": "Bloch oscillations of topological edge modes: Under the action of a weak constant force a wavepacket in periodic potential\nundergoes periodic oscillations in space, returning to the initial position\nafter one oscillation cycle. This wave phenomenon, known as Bloch oscillations\n(BOs), pertains to many physical systems. Can BOs also occur in topological\ninsulators with topologically protected edge states? This question is highly\nnontrivial, because in topological insulators with broken time-reversal\nsymmetry, the edge states propagate unidirectionally without backscattering,\nhence BOs that typically involve stages, where wavepacket moves along and\nagainst the direction of the force, seem to be impossible in such systems when\nforce acts parallel to the edge of the insulator. Here we reveal that BOs still\noccur with topological edge states, but in a nonconventional way: they are\naccompanied not only by oscillations along the edge in the direction of force,\nbut also by oscillations in the direction transverse to that of the force. Full\nBO cycle involves switching between edge states at the opposite edges through\ndelocalized bulk modes. Bloch oscillations of the topological edge states\nrequire to scan the first Brillouin zone twice to complete one cycle, thus they\nhave a period that is two times larger than the period of usual BOs. All these\nunusual properties are in contrast to BOs in non-topological systems."
    },
    {
        "anchor": "Exchange-mediated dynamic screening in the integer quantum Hall regime: We study many-body interaction effects in the spatially-resolved filling\nfactor ($\\nu$) distribution for higher Landau levels (LLs) via self-consistent\nHartree-Fock simulations in the integer quantum Hall (IQH) regime. Our results\nindicate a strong, interaction-induced tendency to avoid the simultaneous\nexistence of partially filled spin-up and spin-down LLs. Rather, we find that\nsuch partially filled LLs consist of coexisting regions of full and empty LLs.\nAt the boundaries between the regions of full and empty LLs, we observe edge\nstripes of nearly constant $\\nu$ close to half-odd filling. This suggests that\nthe exchange interaction induces a behavior similar to a Hund's rule for the\noccupation of the spin split LLs. The screening of the disorder and edge\npotential appears significantly reduced as compared to static Thomas-Fermi\nscreening. Our results are consistent with a local, lateral $\\nu$ dependence of\nthe exchange-enhanced spin splitting. Hence, on quantum-coherent length scales\nas probed here, the electron system of the IQH effect behaves similar to a\nnon-interacting single particle system - not because of the absence, but rather\ndue to the dominance of many-body effects.",
        "positive": "Spin depolarization in the transport of holes across\n  GaMnAs/GaAlAs/p-GaAs: We study the spin polarization of tunneling holes injected from ferromagnetic\nGaMnAs into a p-doped semiconductor through a tunneling barrier. We obtain an\nupper limit to the spin injection rate. We find that spin-orbit interaction\ninteraction in the barrier and in the drain limits severely spin injection.\nSpin depolarization is stronger when the magnetization is parallel to the\ncurrent than when is perpendicular to it."
    },
    {
        "anchor": "Observation of the double quantum spin Hall phase in moir\u00e9 WSe2: Quantum spin Hall (QSH) insulators are a topologically protected phase of\nmatter in two dimensions that can support non-dissipative spin transport. A\nhallmark of the phase is a pair of helical edge states surrounding an\ninsulating bulk. A higher (even) number of helical edge state pairs is usually\nnot possible in real materials because spin mixing would gap out the edge\nstates. Multiple pairs of helical edge states have been proposed in materials\nwith spin conservation symmetry and high spin Chern bands, but remained\nexperimentally elusive. Here, we demonstrate a QSH phase with one and two pairs\nof helical edge states in twisted bilayer WSe2 at moir\\'e hole filling factor\n{\\nu}= 2 and 4, respectively. We observe nearly quantized conductance or\nresistance plateaus of h/({\\nu}e^2 ) at {\\nu} = 2 and 4 while the bulk is\ninsulating. The conductance is nearly independent of out-of-plane magnetic\nfield and decreases under an in-plane magnetic field. We also observe nonlocal\ntransport, which is sensitive only to the in-plane magnetic field. The results\nagree with quantum transport of helical edge states protected by Ising spin\nconservation symmetry and open a promising platform for low-power spintronics.",
        "positive": "Spin liquids from Majorana Zero Modes in a Cooper Box: We propose a path for constructing diverse interacting spin systems from\ntopological nanowires in Cooper Boxes. The wires are grouped into a three-wire\nbuilding block called an 'hexon', consisting of six Majorana zero modes. In the\npresence of a strong charging energy, the hexon becomes a Cooper box equivalent\nto two spin-$1/2$ degrees of freedom. By considering arrays of hexons and\ncontrolling the distances between the various wires, one can tune the\nHamiltonian governing the low-energy spins, thus providing a route for\ncontrollably constructing interacting spin systems in one- and two-dimensions.\nWe explicitly present realizations of the one-dimensional spin-$1/2$ XXZ chain,\nas well as the transverse field Ising model. We propose an experiment capable\nof revealing the nature of critical points in such effective spin systems by\napplying a local gate voltage and measuring the induced charge at a distance.\nTo demonstrate the applicability of this approach to two-dimensions, we provide\na scheme for realizing the topologically ordered Yao-Kivelson spin-liquid\nmodel, which has a collective Majorana edge mode, similar to the B-phase of\nKitaev's honeycomb model."
    },
    {
        "anchor": "Tunneling in ABC trilayer graphene superlattice: We investigate the transport properties of Dirac fermions in ABC trilayer\ngraphene {(ABC-TLG)} superlattices. Based on the transfer matrix method and\nusing the continuity conditions of the system, we calculate the transmission\nprobabilities {and the corresponding conductance}. In the context of two-band\ntunneling, Klein tunneling is observed, but it decreases with an increase in\nthe number of cells. An interlayer bias opens a gap when the number of cells is\nincreased. Furthermore, increasing the barrier/well width and the cell number\nresults in an increase in the number of gaps and oscillations in both two-band\nand six-band cases. Asymmetry is found in the scattered transmission due to the\npresence of the interlayer bias. The conductance decreases when the number of\ncells increases and a gap region is found. Our results indicate that adjusting\nthe number of cells, the width of the barrier/well, and the barrier heights\nmakes it possible to control electron tunneling and the gap number in ABC-TLG.\nThese findings provide valuable insights for the development of electronic\ndevices using graphene materials.",
        "positive": "Dynamics of heat transfer between nano systems: We develop a dynamical theory of heat transfer between two nano systems. In\nparticular, we consider the resonant heat transfer between two nanoparticles\ndue to the coupling of localized surface modes having a finite spectral width.\nWe model the coupled nanosystem by two coupled quantum mechanical oscillators,\neach interacting with its own heat bath, and obtain a master equation for the\ndynamics of heat transfer. The damping rates in the master equation are related\nto the lifetimes of localized plasmons in the nanoparticles. We study the\ndynamics towards the steady state and establish connection with the standard\ntheory of heat transfer in steady state. For strongly coupled nano particles we\npredict Rabi oscillations in the mean occupation number of surface plasmons in\neach nano particle."
    },
    {
        "anchor": "Dual Topological Insulator Device with Disorder Robustness: Two-dimensional Na$_3$Bi is a dual topological insulator protected by\ntime-reversal and mirror symmetry, resulting in a promising platform for\ndevices design. However, in reality, the design of topological devices is\nhindered by a sensitivity against disorder and temperature. We study the\ntopological properties of Na$_3$Bi in the presence of intrinsic defects,\ninvestigating the robustness of the edge states and the resulting transport\nproperties. We apply a recursive Green's function technique enabling the study\nof disordered systems with lengths comparable to experimentally synthesized\nmaterials, in the order of micrometers. We combine our findings to propose a\ntopological insulator device, where intrinsic defects are used to filter the\nresponse of trivial bulk states. This results in a stable conductance\nthroughout a large range of electronic temperatures, and controllable by a\nperpendicular electric field. Our proposal is general, enabling the design of\nvarious dual topological insulators devices.",
        "positive": "Conveyor-mode single-electron shuttling in Si/SiGe for a scalable\n  quantum computing architecture: Small spin-qubit registers defined by single electrons confined in Si/SiGe\nquantum dots operate successfully and connecting these would permit scalable\nquantum computation. Shuttling the qubit carrying electrons between registers\nis a natural choice for high-fidelity coherent links provided the overhead of\ncontrol signals stays moderate. Our proof-of-principle demonstrates shuttling\nof a single electron by a propagating wave-potential in an electrostatically\ndefined 420 nm long Si/SiGe quantum-channel. This conveyor-mode shuttling\napproach requires independent from its length only four sinusoidal control\nsignals. We discuss the tuning of the signal parameters, detect the smoothness\nof the electron motion enabling the mapping of potential disorder and observe a\nhigh single-electron shuttling fidelity of $99.42\\pm0.02\\,\\%$ including a\nreversal of direction. Our shuttling device can be readily embedded in\nindustrial fabrication of Si/SiGe qubit chips and paves the way to solving the\nsignal-fanout problem for a fully scalable semiconductor quantum-computing\narchitecture."
    },
    {
        "anchor": "Anisotropic g factor in InAs self-assembled quantum dots: We investigate the wave functions, spectrum, and g-factor anisotropy of\nlow-energy electrons confined to self-assembled, pyramidal InAs quantum dots\n(QDs) subject to external magnetic and electric fields. We present the\nconstruction of trial wave functions for a pyramidal geometry with hard-wall\nconfinement. We explicitly find the ground and first excited states and show\nthe associated probability distributions and energies. Subsequently, we use\nthese wave functions and 8-band $k\\cdot p$ theory to derive a Hamiltonian\ndescribing the QD states close to the valence band edge. Using a perturbative\napproach, we find an effective conduction band Hamiltonian describing\nlow-energy electronic states in the QD. From this, we further extract the\nmagnetic field dependent eigenenergies and associated g factors. We examine the\ng factors regarding anisotropy and behavior under small electric fields. In\nparticular, we find strong anisotropies, with the specific shape depending\nstrongly on the considered QD level. Our results are in good agreement with\nrecent measurements [Takahashi et al., Phys. Rev. B 87, 161302 (2013)] and\nsupport the possibility to control a spin qubit by means of g-tensor\nmodulation.",
        "positive": "Andreev bound states and current-phase relations in three-dimensional\n  topological insulators: To guide the search for the Majorana fermion, we theoretically study\nsuperconductor/topological/superconductor (S/TI/S) junctions in an\nexperimentally relevant regime. We find that the striking features present in\nthese systems, including the doubled periodicity of the Andreev bound states\n(ABSs) due to tunneling via Majorana states, can still be present at high\nelectron densities. We show that via the inclusion of magnetic layers, this 4pi\nperiodic ABS can still be observed in three-dimensional topological insulators,\nwhere finite angle incidence usually results in the opening of a gap at zero\nenergy and hence results in a 2pi periodic ABS. Furthermore, we study the\nJosephson junction characteristics and find that the gap size can be controlled\nand decreased by tuning the magnetization direction and amplitude. These\nfindings pave the way for designing experiments on S/3DTI/S junctions."
    },
    {
        "anchor": "Axial anomaly and longitudinal magnetoresistance of a generic three\n  dimensional metal: We show that the emergence of the axial anomaly is a universal phenomenon for\na generic three dimensional metal in the presence of parallel electric ($E$)\nand magnetic ($B$) fields. In contrast to the expectations of the classical\ntheory of magnetotransport, this intrinsically quantum mechanical phenomenon\ngives rise to the longitudinal magnetoresistance for any three dimensional\nmetal. However, the emergence of the axial anomaly does not guarantee the\nexistence of negative longitudinal magnetoresistance. We show this through an\nexplicit calculation of the longitudinal magnetoconductivity in the quantum\nlimit using the Boltzmann equation, for both short-range neutral and long-range\nionic impurity scattering processes. We demonstrate that the ionic scattering\ncontributes a large positive magnetoconductivity $\\propto B^2$ in the quantum\nlimit, which can cause a strong negative magnetoresistance for any three\ndimensional or quasi-two dimensional metal. In contrast, the finite range\nneutral impurities and zero range point impurities can lead to both positive\nand negative longitudinal magnetoresistance depending on the underlying band\nstructure. In the presence of both neutral and ionic impurities, the\nlongitudinal magnetoresistance of a generic metal in the quantum limit\ninitially becomes negative, and ultimately becomes positive after passing\nthrough a minimum. We discuss in detail the qualitative agreement between our\ntheory and recent observations of negative longitudinal magnetoresistance in\nWeyl semimetals TaAs and TaP, Dirac semimetals Na$_3$Bi, Bi$_{1-x}$Sb$_x$, and\nZrTe$_5$, and quasi-two dimensional metals PdCoO$_2$,\n$\\alpha$-(BEDT-TTF)$_2$I$_3$ which do not possess any bulk three dimensional\nDirac or Weyl quasiparticles.",
        "positive": "Evidence of magnetoelectronic electromagnon mediated transport in\n  flexoelectronic heterostructures: The superposition of atomic vibrations and flexoelectronic effect gives rise\nto a cross correlation between free charge carriers and temporal magnetic\nmoment of phonons in conducting heterostructures under an applied strain\ngradient. The resulting dynamical coupling is expected to give rise to\nquasiparticle excitations called as magnetoelectronic electromagnon that\ncarries electronic charge and temporal magnetic moment. Here, we report\nexperimental evidence of magnetoelectronic electromagnon in the freestanding\ndegenerately doped p-Si based heterostructure thin film samples. These\nquasiparticle excitations give rise to long-distance (>100um) spin transport;\ndemonstrated using spatially modulated transverse magneto-thermoelectric and\nnon-local resistance measurements. The magnetoelectronic electromagnons are\nnon-reciprocal and give rise to large magnetochiral anisotropy (0.352 A-1T-1)\nthat diminishes at lower temperatures. The superposition of non-reciprocal\nmagnetoelectronic electromagnons gives rise to longitudinal and transverse\nmodulations in charge carrier density, spin density and magnetic moment;\ndemonstrated using the Hall effect and edge dependent magnetoresistance\nmeasurements, which can also be called as inhomogeneous magnetoelectronic\nmultiferroic effect. These quasiparticle excitations are analogues to photons\nwhere time dependent polarization and temporal magnetic moment replaces\nelectric and magnetic field, respectively and most likely topological because\nit manifests topological Nernst effect. Hence, the magnetoelectronic\nelectromagnon can potentially give rise to quantum interference and\nentanglement effects in conducting solid state system at room temperature in\naddition to efficient spin transport."
    },
    {
        "anchor": "Efficient Electrical Control of Thin-Film Black Phosphorus Bandgap: Recently rediscovered black phosphorus is a layered semiconductor with\npromising electronic and photonic properties. Dynamic control of its bandgap\ncan enable novel device applications and allow for the exploration of new\nphysical phenomena. However, theoretical investigations and photoemission\nspectroscopy experiments performed on doped black phosphorus through potassium\nadsorption indicate that in its few-layer form, an exceedingly large electric\nfield in the order of several volts per nanometer is required to effectively\ntune its bandgap, making the direct electrical control unfeasible. Here we\ndemonstrate the tuning of bandgap in intrinsic black phosphorus using an\nelectric field directly and reveal the unique thickness-dependent bandgap\ntuning properties, arising from the strong interlayer electronic-state\ncoupling. Furthermore, leveraging a 10-nm-thick black phosphorus in which the\nfield-induced potential difference across the film dominates over the\ninterlayer coupling, we continuously tune its bandgap from ~300 to below 50\nmilli-electron volts, using a moderate displacement field up to 1.1 volts per\nnanometer. Such dynamic tuning of bandgap may not only extend the operational\nwavelength range of tunable black phosphorus photonic devices, but also pave\nthe way for the investigation of electrically tunable topological insulators\nand topological nodal semimetals.",
        "positive": "Computing with spins and magnets: The possible use of spin and magnets in place of charge and capacitors to\nstore and process information is well known. Magnetic tunnel junctions are\nbeing widely investigated and developed for magnetic random access memories.\nThese are two terminal devices that change their resistance based on switchable\nmagnetization of magnetic materials. They utilize the interaction between\nelectron spin and magnets to read information from the magnets and write onto\nthem. Such advances in memory devices could also translate into a new class of\nlogic devices that offer the advantage of nonvolatile and reconfigurable\ninformation processing over transistors. Logic devices having a transistor-like\ngain and directionality could be used to build integrated circuits without the\nneed for transistor-based amplifiers and clocks at every stage. We review\ndevice characteristics and basic logic gates that compute with spins and\nmagnets from the mesoscopic to the atomic scale, as well as materials,\nintegration, and fabrication challenges and methods."
    },
    {
        "anchor": "Design and Characterization of a Field-Switchable Nanomagnetic Atom\n  Mirror: We present a design for a switchable nanomagnetic atom mirror formed by an\narray of 180{\\deg} domain walls confined within Ni80Fe20 planar nanowires. A\nsimple analytical model is developed which allows the magnetic field produced\nby the domain wall array to be calculated. This model is then used to optimize\nthe geometry of the nanowires so as to maximize the reflectivity of the atom\nmirror. We then describe the fabrication of a nanowire array and characterize\nits magnetic behavior using magneto-optic Kerr effect magnetometry, scanning\nHall probe microscopy and micromagnetic simulations, demonstrating how the\nmobility of the domain walls allow the atom mirror to be switched \"on\" and\n\"off\" in a manner which would be impossible for conventional designs. Finally,\nwe model the reflection of 87Rb atoms from the atom mirror's surface, showing\nthat our design is well suited for investigating interactions between domain\nwalls and cold atoms.",
        "positive": "Quasi-particle tunneling at a constriction in a fractional quantum Hall\n  state: Split-gate constrictions can be used to produce controllable scattering in a\nfractional quantum Hall state and constitute a very versatile model system for\nthe investigation of non-Fermi physics in edge states. Controllable inter-edge\ntunneling can be achieved by tuning the constriction parameters and its\nout-of-equilibrium behavior can be explored as well. Here we review our results\nof tunneling non-linearities at a split-gate constriction in a wide range of\ntemperatures and inter-edge coupling. The results are compared to available\ntheoretical predictions of tunneling characteristics between Luttinger liquids.\nWe show how partial agreement with these theoretical models is obtained in\nselected ranges of temperatures and inter-edge coupling, while striking\ndeviations are obtained especially in the low-coupling, low-temperature\nregimes."
    },
    {
        "anchor": "Analytic form of head-to-head domain walls in thin ferromagnetic\n  cylinders: The one-dimensional problem of a static head-to-head domain wall structure in\na thin soft-magnetic nanowire with circular cross-section is treated within the\nframework of micromagnetic theory. A radius-dependent analytic form of the\ndomain wall profile is derived by decomposing the magnetostatic energy into a\nmonopolar and a dipolar term. We present a model in which the dipolar term of\nthe magnetostatic energy resulting from the transverse magnetization in the\ncenter of the domain wall is calculated with Osborn's formulas for\nhomogeneously magnetized ellipsoids [Phys. Rev. 67, 351 (1945)]. The analytic\nresults agree almost perfectly with simulation data as long as the wire\ndiameter is sufficiently small to prevent inhomogeneities of the magnetization\nalong the cross-section. Owing to the recently demonstrated negligible D\\\"oring\nmass of these walls, our results should also apply to the dynamic case, where\ndomain walls are driven by spin-transfer toque effects and/or an axial magnetic\nfield.",
        "positive": "Spin mixing between subbands and extraordinary Landau levels shift in\n  wide HgTe quantum wells: We present both the experimental and theoretical investigation of a\nnon-trivial electron Landau levels shift in magnetic field in wide ~20 nm HgTe\nquantum wells: Landau levels split under magnetic fields but become degenerate\nagain when magnetic field increases. We reproduced this behavior qualitatively\nwithin an isotropic 6-band Kane model, then using semiclassical calculations we\nshowed this behavior is due to the mixing of the conduction band with total\nspin 3/2 with the next well subband with spin 1/2 which reduces the average\nvertical spin from 3/2 to around 1. This change of the average spin changes the\nBerry phase explaining the evolution of Landau levels under magnetic field."
    },
    {
        "anchor": "Towards r-space Bose-Einstein condensation of photonic crystal exciton\n  polaritons: Coupled states of semiconductor quantum well (QW) excitons and photons in a\ntwo dimensional (2D) periodic lattice of microcavities are analyzed\ntheoretically, revealing allowed bands and forbidden gaps in the energy\nspectrum of exciton polaritons. Photonic crystal exciton polaritons have\nspatially uniform excitonic constituent set by flat QWs, but exhibit periodic\nBloch oscillations in the plane of QWs due to their photonic component. The\nenvelope functions of photonic crystal exciton polaritons can be tailored via\neffective potential of a photonic crystal heterostructure, by using\nquasi-periodic lattices of microcavities. Confined envelope function states of\nlower and upper polaritons and the Bose-Einstein condensation of lower\npolaritons are analyzed here in a photonic crystal heterostructure trap with\nharmonic oscillator potential. This concept is numerically illustrated on\nexample of CdTe/CdMgTe microcavities.",
        "positive": "Spectrum of exciton states in monolayer transition metal\n  dichalcogenides: angular momentum and Landau levels: A four-band exciton Hamiltonian is constructed starting from the\nsingle-particle Dirac Hamiltonian for charge carriers in monolayer transition\nmetal dichalcogenides (TMDs). The angular part of the exciton wave function can\nbe separated from the radial part, in the case of zero center of mass momentum\nexcitons, by exploiting the eigenstates of the total exciton angular momentum\noperator with which the Hamiltonian commutes. We explain why this approach\nfails for excitons with finite center of mass momentum or in the presence of a\nperpendicular magnetic field and present an approximation to resolve this\nissue. We calculate the (binding) energy and average interparticle distance of\ndifferent excited exciton states in different TMDs and compare these with\nresults available in the literature. Remarkably, we find that the intervalley\nexciton ground state in the $\\mp K$ valley has angular momentum $j=\\pm1$, which\nis due to the pseudospin of the separate particles. The exciton mass and the\nexciton Landau levels are calculated and we find that the degeneracy of exciton\nstates with opposite relative angular momentum is altered by a magnetic field."
    },
    {
        "anchor": "Rapidly rotating boson molecules with long or short range repulsion: an\n  exact diagonalization study: The Hamiltonian for a small number, N <= 11, of bosons in a rapidly rotating\nharmonic trap, interacting via a short range (contact potential) or a long\nrange (Coulomb) interaction, is studied via an exact diagonalization in the\nlowest Landau level. Our analysis shows that, for both low and high fractional\nfillings, the bosons localize and form rotating boson molecules (RBMs)\nconsisting of concentric polygonal rings. Focusing on systems with the number\nof trapped atoms sufficiently large to form multi-ring bosonic molecules, we\nfind that, as a function of the rotational frequency and regardless of the type\nof repulsive interaction, the ground-state angular momenta grow in specific\nsteps that coincide with the number of localized bosons on each concentric\nring. Comparison of the conditional probability distributions (CPDs) for both\ninteractions suggests that the degree of crystalline correlations appears to\ndepend more on the fractional filling nu than on the range of the interaction.\nThe RBMs behave as nonrigid rotors, i.e., the concentric rings rotate\nindependently of each other. At filling fractions nu < 1/2, we observe well\ndeveloped crystallinity in the CPDs (two-point correlation functions). For\nlarger filling fractions nu > 1/2, observation of similar molecular patterns\nrequires consideration of even higher-order correlation functions.",
        "positive": "Coulomb interaction-induced Aharonov-Bohm oscillations: We study the Coulomb interaction-induced Aharonov-Bohm (AB) oscillations in\nthe linear response transport through a remote quantum dot which has no tunnel\ncoupling but has Coulomb coupling with the quantum dot embedded in an AB\ninterferometer. We show that the Coulomb interaction-induced AB effect is\ncharacterized by a charge susceptibility of a remote quantum dot in a weak\ninteraction regime. In a strong but finite interaction regime, around the\nparticle-hole symmetric point, there exists the region where the visibility of\nthe induced AB oscillations becomes one although the visibility of the original\nAB oscillations in the interferometer is low."
    },
    {
        "anchor": "Non-Hermitian band theory in all dimensions: uniform spectra and skin\n  effect: The non-Hermitian skin effect is an iconic phenomenon characterized by the\naggregation of eigenstates near the system boundaries in non-Hermitian systems.\nWhile extensively studied in one dimension, understanding the skin effect and\nextending the non-Bloch band theory to higher dimensions encounters a\nformidable challenge, primarily due to infinite lattice geometries or open\nboundary conditions. This work adopts a point-gap perspective and presents a\nunified non-Hermitian band theory that governs skin effects across all spatial\ndimensions. We introduce the concept of uniform spectra and reveal that\nregardless of lattice geometry, their energy spectra are universally given by\nthe uniform spectra, even though their manifestations of skin modes may differ.\nBuilding on the uniform spectra, we demonstrate how to account for the skin\neffect with generic lattice cuts and establish the connections of skin modes\nacross different geometric shapes via momentum-basis transformations. Our\nfindings highlight the pivotal roles point gaps play, offering a unified\nunderstanding of the non-Hermitian skin effect in all dimensions.",
        "positive": "Adsorption of Br$_2$ onto Small Au Nanoclusters: Au nanoclusters grown on SiO$_2$ by physical vapor deposition are exposed to\nBr$_2$ and then measured with 1.5 keV Na$^+$ low energy ion scattering. It is\nfound that the clusters are able to dissociate the molecules which then adsorb\nas individual Br atoms, but Br$_2$ does not stick to the bare substrate nor to\nbulk Au. Adsorption is the first step in any surface chemical reaction, and\nthis result shows how nanoclusters can induce adsorption of species that\notherwise do not stick. Results from the literature indicate that catalysis\ninvolving nanoclusters occurs at the edges and that the edge atoms are\npositively charged. This information in conjunction with the ion scattering\nresults lead to the conclusion that the Br adatoms are negatively charged and\nionically bonded at the edges of the clusters. Br$_2$ is also a known catalytic\npoison and this work shows how its adsorption blocks sites that would otherwise\nbe involved in nanocatalysis."
    },
    {
        "anchor": "Distribution of current fluctuations in a bistable conductor: We measure the full distribution of current fluctuations in a single-electron\ntransistor with a controllable bistability. The conductance switches randomly\nbetween two levels due to the tunneling of single electrons in a separate\nsingle-electron box. The electrical fluctuations are detected over a wide range\nof time scales and excellent agreement with theoretical predictions is found.\nFor long integration times, the distribution of the time-averaged current obeys\nthe large-deviation principle. We formulate and verify a fluctuation relation\nfor the bistable region of the current distribution.",
        "positive": "Mesoscopic transport and quantum chaos: The field of Quantum Chaos, addressing the quantum manifestations of an\nunderlying classically chaotic dynamics, was developed in the early eighties,\nmainly from a theoretical perspective. Few experimental systems were initially\nrecognized to exhibit the versatility of being sensitive, at the same time, to\ntheir classical and quantum dynamics. Rydberg atoms provided the main testing\nground of Quantum Chaos concepts until the early nineties, marked by the\ndevelopment of microwave billiards, ultra-cold atoms in optical lattices, and\nlow-temperature transport in mesoscopic semiconductor structures. The\nmesoscopic regime is attained in small condensed matter systems at sufficiently\nlow temperatures for the electrons to propagate coherently across the sample.\nThe quantum coherence of electrons, together with the ballistic motion\ncharacteristic of ultra-clean microstructures, motivated the proposal of\nmesocopic systems as a very special laboratory for performing measurements and\ntesting the theoretical ideas of Quantum Chaos. Experimental realizations and\nmany important developments, reviewed in this article, followed from such a\nconnection."
    },
    {
        "anchor": "Direct evidence of spin-split one-dimensional metallic surface state on\n  Si(557)-Au: We report unprecedented evidence of a spin split one-dimensional metallic\nsurface state for the system of Si(557)-Au obtained by means of high-resolution\nspin- and angle-resolved photoelectron spectroscopy combined with first\nprinciples calculations. The surface state shows double parabolic energy\ndispersions along the Au chain structure together with a reversal of the spin\npolarization with respect to the time-reversal symmetry point as is\ncharacteristic from the Rashba effect. Moreover, we have observed a\nconsiderably large out-of-plane spin polarization which we attribute to the\nhighly anisotropic wave function of the gold chains.",
        "positive": "Spin correlations in spin blockade: We investigate spin currents and spin-current correlations for double quantum\ndots in the spin blockade regime. By analysing the time evolution of the\ndensity matrix, we obtain the spin resolved currents and derive from a\ngenerating function an expression for the fluctuations and correlations. Both\nthe charge current and the spin current turn out to be generally\nsuper-Poissonian. Moreover, we study the influence of ac fields acting upon the\ntransported electrons. In particular, we focus on fields that cause spin\nrotation or photon-assisted tunnelling."
    },
    {
        "anchor": "On deformation of carbon nanotubes with TersoffCG: a case study: Recently, TersoffCG, a coarse grain potential for graphene based on Tersoff\npotential, has been developed. In this work, we explore this potential,\napplying it to the case study of a single wall carbon nanotube. We performed a\nseries of molecular dynamics simulations of longitudinal tension and\ncompression on armchair carbon nanotubes, comparing two full atomistic models,\ndescribed by means Tersoff and AIREBO potentials, and the coarse grained model\ndescribed by means of TersoffCG. We followed each stage and mode of\ndeformation, finding a good matching between the stress strain curves under\ntension independently from the used potential, with a small difference in the\npre-fracture zone. Conversely, under compression the coarse grain model\npresents a buckling stress almost the double of the full atomistic models, and\na more than double post-buckling stress. With the increase of the nanotube\ndiameter, the capturing of the buckling modes is enhanced, however the stress\noverestimation remains. A decreasing of the three body angular term in the\npotential can be a rough way to recover the buckling stress, with small losses\nin the capturing of the post-buckling behavior. In spite of a good agreement\nunder compression, the fracture behavior of the nanotube is strongly\ninfluenced, suggesting this modification only when no fractures are present.\nThe findings reported in this work underlie the necessity of accurately\nevaluate the use of a coarse grain model when compressive loads are applied to\nthe system during the simulation.",
        "positive": "Topological edge and corner states and fractional corner charges in blue\n  phosphorene: We theoretically study emergent edge and corner states in monolayer blue\nphosphorus (blue phosphorene) using the first-principles calculation and\ntight-binding model. We show that the existence of the Wannier orbitals at\nevery bond center yields edge states both in zigzag and armchair nanoribbons.\nThe properties of the edge states can be well described by a simple effective\nHamiltonian for uncoupled edge orbitals, where the structural relaxation near\nthe boundary significantly affects the edge band structure. For corner states,\nwe examine two types of corner structures consisting of zigzag and armchair\nedges, where we find that multiple corner states emerge in the bulk gap as a\nconsequence of hybridization of edge and corner uncoupled orbitals. In the\narmchair corner, in particular, we demonstrate that corner states appear right\nat the Fermi energy, which leads to the emergence of fractional corner charge\ndue to filling anomaly. Finally, we discuss the relationship between blue\nphosphorene and black phosphorene, and show that two systems share the\nequivalent Wannier orbital positions and similar edge/corner state properties\neven though their atomic structures are totally different."
    },
    {
        "anchor": "On the Bott index of unitary matrices on a finite torus: This article reviews the foundations of the theory of the Bott index of a\npair of unitary matrices in the context of condensed matter theory, as\ndeveloped by Hastings and Loring in J. Math. Phys. (51), 015214, (2010) and\nAnnals of Physics 326 (2011) 1699-1759, providing a novel proof of the equality\nwith the Chern number. The Bott index is defined for a pair of unitary\nmatrices, then extended to a pair of invertible matrices and homotopic\ninvariance of the index is proven. An insulator defined on a lattice on a\n2-torus, that is a rectangular lattice with periodic boundary conditions, is\nconsidered and a pair of quasi-unitary matrices associated to this physical\nsystem are introduced. It is shown that their Bott index is well defined and\nthe connection with the transverse conductance, the Chern number, is\nestablished proving the equality of the two quantities.",
        "positive": "Tuning Negative Differential Resistance in a Molecular Film: We have observed tunable negative differential resistance (NDR) in scanning\ntunneling spectroscopy measurements of a double layer of C60 molecules on a\nmetallic surface. Using a simple model we show that the observed NDR behavior\nis explained by voltage-dependent changes in the tunneling barrier height."
    },
    {
        "anchor": "Optical and electronic properties of two dimensional graphitic silicon\n  carbide: Optical and electronic properties of two dimensional few layers graphitic\nsilicon carbide (GSiC), in particular monolayer and bilayer, are investigated\nby density functional theory and found different from that of graphene and\nsilicene. Monolayer GSiC has direct bandgap while few layers exhibit indirect\nbandgap. The bandgap of monolayer GSiC can be tuned by an in-plane strain.\nProperties of bilayer GSiC are extremely sensitive to the interlayer distance.\nThese predictions promise that monolayer GSiC could be a remarkable candidate\nfor novel type of light-emitting diodes utilizing its unique optical properties\ndistinct from graphene, silicene and few layers GSiC.",
        "positive": "Anomalous Hall Effect in ZrTe5: ZrTe$_5$ has been of recent interest as a potential Dirac/Weyl semimetal\nmaterial. Here, we report the results of experiments performed via in-situ 3D\ndouble-axis rotation to extract the full $4\\pi$ solid angular dependence of the\ntransport properties. A clear anomalous Hall effect (AHE) was detected for\nevery sample, with no magnetic ordering observed in the system to the\nexperimental sensitivity of torque magnetometry. Interestingly, the AHE takes\nlarge values when the magnetic field is rotated in-plane, with the values\nvanishing above $\\sim 60$ K where the negative longitudinal magnetoresistance\n(LMR) also disappears. This suggests a close relation in their origins, which\nwe attribute to Berry curvature generated by the Weyl nodes."
    },
    {
        "anchor": "Structure and stability of trapped atomic boson-fermion mixtures: The structure of binary mixtures of bosonic and fermionic atoms in an\nexternal trapping potential at zero temperature is studied on the basis of a\nmodified Gross-Pitaevskii equation for the bosonic component which\nself-consistently includes the mean-field interaction generated by the\nfermionic cloud. The density of the fermionic component is described within the\nThomas-Fermi approximation. The influence of the boson-boson and the\nboson-fermion s-wave interaction on the density profiles and the stability of\nthe mixture is investigated systematically. Critical particle numbers for the\nmean-field collapse caused either by attractive boson-boson or by attractive\nboson-fermion interactions and for the onset of spatial component separation\nare discussed. It is shown that the interplay between the boson-boson and the\nboson-fermion interaction generates a rich and complex phase diagram. Finally,\nthe specific properties and prospects of the boson-fermion mixtures available\nin present experiments are addressed.",
        "positive": "On Three \"Anomalous\" Measurements of Nonlinear QPC Conductance: Practical mesoscopic devices based on quantum point contacts (QPCs) must\nfunction at operating point involving large internal driving fields.\nExperimental evidence has accumulated to display anomalous nonlinear features\nof QPC response beyond the capacities of accepted tunnelling-based models of\nnonlinear quantum transport. Here we recall the physical setting of three\nanomalous QPC experiments and review how, for two of them, a microscopically\nbased nonequilibrium quantum kinetic description (the correct physical boundary\nconditions being crucial) has already overcome the predictive limitations of\nstandard nonequilibrium mesoscopic models. The third experiment remains a\nsignificant challenge to all theorists."
    },
    {
        "anchor": "Superconducting Spintronic Heat Engine: Heat engines are key devices that convert thermal energy into usable energy.\nStrong thermoelectricity, at the basis of electrical heat engines, is present\nin superconducting spin tunnel barriers at cryogenic temperatures where\nconventional semiconducting or metallic technologies cease to work. Here we\nrealize a superconducting spintronic heat engine consisting of a ferromagnetic\ninsulator/superconductor/insulator/ferromagnet tunnel junction\n(EuS/Al/AlO$_x$/Co). The efficiency of the engine is quantified for bath\ntemperatures ranging from 25 mK up to 800 mK, and at different load\nresistances. Moreover, we show that the sign of the generated thermoelectric\nvoltage can be inverted according to the parallel or anti-parallel orientation\nof the two ferromagnetic layers, EuS and Co. This realizes a thermoelectric\nspin valve controlling the sign and strength of the Seebeck coefficient,\nthereby implementing a thermoelectric memory cell. We propose a theoretical\nmodel that allows describing the experimental data and predicts the engine\nefficiency for different device parameters.",
        "positive": "Quantum transport simulation scheme including strong correlations and\n  its application to organic radicals adsorbed on gold: We present a computational method to quantitatively describe the\nlinear-response conductance of nanoscale devices in the Kondo regime. This\nmethod relies on a projection scheme to extract an Anderson impurity model from\nthe results of density functional theory and non-equilibrium Green's functions\ncalculations. The Anderson impurity model is then solved by continuous time\nquantum Monte Carlo. The developed formalism allows us to separate the\ndifferent contributions to the transport, including coherent or non-coherent\ntransport channels, and also the quantum interference between impurity and\nbackground transmission. We apply the method to a scanning tunneling microscope\nsetup for the 1,3,5-triphenyl-6-oxoverdazyl (TOV) stable radical molecule\nadsorbed on gold. The TOV molecule has one unpaired electron, which when\nbrought in contact with metal electrodes behaves like a prototypical single\nAnderson impurity. We evaluate the Kondo temperature, the finite temperature\nspectral function and transport properties, finding good agreement with\npublished experimental results."
    },
    {
        "anchor": "Experimental parameters, combined dynamics, and nonlinearity of a\n  Magnonic-Opto-Electronic Oscillator (MOEO): We report the construction and characterization of a comprehensive\nmagnonic-opto-electronic oscillator (MOEO) system based on 1550-nm photonics\nand yttirum iron garnet (YIG) magnonics. The system exhibits a rich and\nsynergistic parameter space because of the ability to control individual\nphotonic, electronic, and magnonic components. Taking advantage of the spin\nwave dispersion of YIG, the frequency self-generation as well as the related\nnonlinear processes become sensitive to the external magnetic field. Besides\nbeing known as a narrowband filter and a delay element, the YIG delayline\npossesses spin wave modes that can be controlled to mix with the optoelectronic\nmodes to generate higher-order harmonic beating modes. With the high\nsensitivity and external tunability, the MOEO system may find usefulness in\nsensing applications in magnetism and spintronics beyond optoelectronics and\nphotonics.",
        "positive": "Enhanced photocurrent readout for a quantum dot qubit by bias modulation: We demonstrate coherent control of a quantum dot exciton using photocurrent\ndetection with a sinusoidal reverse bias. Optical control is performed at low\nbias, where tunneling-limited coherence times are long. Following this step,\nthe tunneling rates are increased to remove the long-lived hole, achieving a\nhigh photocurrent signal. For a detection efficiency of 68%, electron and hole\ntunneling times during optical control of 200 ps and 20 ns can be achieved,\ncompared to 120 ps and 7 ns for the constant bias case, respectively."
    },
    {
        "anchor": "Formation of Atomic-Sized Contacts by Electrochemical Methods: Electrochemical methods have recently become an interesting tool for\nfabricating and characterizing nanostructures at room temperature. Simplicity,\nlow cost and reversibility are some of the advantages of this technique that\nallows to work at the nanoscale without requiring sophisticated\ninstrumentation. In our experimental setup, we measure the conductance across a\nnanocontact fabricated either by dissolving a macroscopic gold wire or by\ndepositing gold in between two separated gold electrodes. We have achieved a\nhigh level of control on the electrochemical fabrication of atomic-sized\ncontacts in gold. The use of electrochemistry as a reproducible technique to\nprepare nanocontacts will open several possibilities that are not feasible with\nother methodologies. It involves, also, the possibility of reproducing\nexperiments that today are made by more expensive, complicated or irreversible\nmethods. As example, we show here a comparison of the results when looking for\nshell effects in gold nanocontacts with those obtained by other techniques.",
        "positive": "Incoherent Mollow triplet: A counterpart of the Mollow triplet (luminescence lineshape of a two-level\nsystem under coherent excitation) is obtained for the case of incoherent\nexcitation in a cavity. Its analytical expression, in excellent agreement with\nnumerical results, pinpoints analogies and differences between the conventional\nresonance fluorescence spectrum and its cavity QED analogue under incoherent\nexcitation."
    },
    {
        "anchor": "Quantum feedback at the solid-liquid interface: flow-induced electronic\n  current and its negative contribution to friction: An electronic current driven through a conductor can induce a current in\nanother conductor through the famous Coulomb drag effect. Similar phenomena\nhave been reported at the interface between a moving fluid and a conductor, but\ntheir interpretation has remained elusive. Here, we develop a\nquantum-mechanical theory of the intertwined fluid and electronic flows, taking\nadvantage of the non-equilibrium Keldysh framework. We predict that a globally\nneutral liquid can generate an electronic current in the solid wall along which\nit flows. This hydrodynamic Coulomb drag originates from both the Coulomb\ninteractions between the liquid's charge fluctuations and the solid's charge\ncarriers, and the liquid-electron interaction mediated by the solid's phonons.\nWe derive explicitly the Coulomb drag current in terms of the solid's\nelectronic and phononic properties, as well as the liquid's dielectric\nresponse, a result which quantitatively agrees with recent experiments at the\nliquid-graphene interface. Furthermore, we show that the current generation\ncounteracts momentum transfer from the liquid to the solid, leading to a\nreduction of the hydrodynamic friction coefficient through a quantum feedback\nmechanism. Our results provide a roadmap for controlling nanoscale liquid flows\nat the quantum level, and suggest strategies for designing materials with low\nhydrodynamic friction.",
        "positive": "Electron-hole Hybridization in Bilayer Graphene: Band structure determines the motion of electrons in a solid, giving rise to\nexotic phenomena when properly engineered. Drawing an analogy between electrons\nand photons, artificially designed optical lattices indicate the possibility of\na similar band modulation effect in graphene systems. Yet due to the fermionic\nnature of electrons, modulated electronic systems promise far richer categories\nof behaviors than those found in optical lattices. Here, we uncovered a strong\nmodulation of electronic states in bilayer graphene subject to periodic\npotentials. We observed for the first time the hybridization of electron and\nhole sub-bands, resulting in local band gaps at both primary and secondary\ncharge neutrality points. Such hybridization leads to the formation of flat\nbands, enabling the study of correlated effects in graphene systems. This work\nmay also offer a viable platform to form and continuously tune Majorana zero\nmodes, which is important to the realization of topological quantum\ncomputation."
    },
    {
        "anchor": "Possible dimensionality transition behavior in localized plasmon\n  resonances of confinement-controlled graphene devices: We investigated the dimensionality transition behavior of graphene localized\nplasmon resonances in confinement-controlled graphene devices. We first\ndemonstrated a possibility of dimensionality transition, based on the devices\ncarrier-density dependence, from a two-dimensional plasmon resonance to a\none-dimensional plasmon one. We fabricated optical transparent devices and\nelectrical transport devices on the same optical transparent wafer. These\ndevices allow detailed control and analysis between carrier density and plasmon\nresonance peak positions. The carrier density from square root n\n(two-dimensional) to constant (one-dimensional) is consistent with the\ntheoretical predictions based on the Dirac Fermion carriers in linear-band\nstructure materials.",
        "positive": "Direct Measurements of Magnetic Polarons in Cd$_{1-x}$Mn$_x$Se\n  Nanocrystals from Resonant Photoluminescence: In semiconductors, quantum confinement can greatly enhance the interaction\nbetween band carriers (electrons and holes) and dopant atoms. One manifestation\nof this enhancement is the increased stability of exciton magnetic polarons in\nmagnetically-doped nanostructures. In the limit of very strong 0D confinement\nthat is realized in colloidal semiconductor nanocrystals, a single exciton can\nexert an effective exchange field $B_{\\rm{ex}}$ on the embedded magnetic\ndopants that exceeds several tesla. Here we use the very sensitive method of\nresonant photoluminescence (PL) to directly measure the presence and properties\nof exciton magnetic polarons in colloidal Cd$_{1-x}$Mn$_x$Se nanocrystals.\nDespite small Mn$^{2+}$ concentrations ($x$=0.4-1.6\\%), large polaron binding\nenergies up to $\\sim$26~meV are observed at low temperatures via the\nsubstantial Stokes shift between the pump laser and the resonant PL maximum,\nindicating nearly complete alignment of all Mn$^{2+}$ spins by $B_{\\rm{ex}}$.\nTemperature and magnetic field-dependent studies reveal that $B_{\\rm{ex}}\n\\approx$ 10~T in these nanocrystals, in good agreement with theoretical\nestimates. Further, the emission linewidths provide direct insight into the\nstatistical fluctuations of the Mn$^{2+}$ spins. These resonant PL studies\nprovide detailed insight into collective magnetic phenomena, especially in\nlightly-doped nanocrystals where conventional techniques such as nonresonant PL\nor time-resolved PL provide ambiguous results."
    },
    {
        "anchor": "Dipole coupling of a tunable hole double quantum dot in germanium hut\n  wire to a microwave resonator: The germanium (Ge) hut wire system has strong spin-orbit coupling, a long\ncoherence time due to a very large heavy-light hole splitting, and the\nadvantage of site-controlled large-scale hut wire positioning. These properties\nmake the Ge hut wire a promising candidate for the realization of strong\ncoupling of spin to superconducting resonators and scalability for multiple\nqubit coupling. We have coupled a reflection line resonator to a hole double\nquantum dot (DQD) formed in Ge hut wire. The amplitude and phase responses of\nthe microwave resonator revealed that the charge stability diagrams of the DQD\nare in good agreement with those obtained from transport measurements. The DQD\ninterdot tunneling rate is shown to be tunable from 6.2 GHz to 8.5 GHz, which\ndemonstrates the ability to adjust the frequency detuning between the qubit and\nthe resonator. Furthermore, we achieved a hole-resonator coupling strength of\nup to 15 MHz, with a charge qubit decoherence rate of 0.28 GHz. Meanwhile the\nhole spin-resonator coupling rate was estimated to be 3 MHz. These results\nsuggest that holes of a DQD in a Ge hut wire are dipole coupled to microwave\nphotons, potentially enabling tunable hole spin-photon interactions in Ge with\nan inherent spin-orbit coupling.",
        "positive": "How will freestanding borophene nanoribbons look like? An analysis of\n  their possible structures, magnetism and transport properties: We report a density-functional-theoretic study of the stability and\nelectronic structure of two recently proposed borophene sheets with Pmmn\nsymmetry and nonzero thickness. We then investigate nanoribbons (BNRs) derived\nfrom these nanostructures, with particular attention to technologically\nrelevant properties like magnetism and electronic transport. We consider two\nperpendicular directions for the edges of the stripes as well as different\nlateral widths. We show that the Pmmn8 sheet, with 8 atoms in its unit cell and\ngenerated by two interpenetrating lattices, has a larger binding energy than\nthe Pmmn2 sheet, with only 2 atoms per unit cell. We also use their phonon\nspectra to show that the mechanical stability of the Pmmn8 sheet is superior to\nthat of the Pmmn2 sheet. Nanoribbons derived from Pmmn8 are not only more\nstable than those derived from Pmmn2, but also more interesting from the\ntechnological point of view. We find a rich variety of magnetic solutions,\ndepending on the borophene \"mother structure\", edge orientation, width and, in\nthe case of Pmmn8-derived BNRs, the sublattice of edge atoms. We show that one\ncan build BNRs with magnetic moment in both, one or none of the edges, as well\nas with parallel or antiparallel magnetic coupling between the edges when\nmagnetic; moreover, their electronic character can be semiconducting, metallic\nor half-metallic, creating a perfect spin valve at low bias. These different\nbehaviors are reflected in their densities of states, spin density and\nelectronic transport coefficients, which are analyzed in detail. Our work\nprovides a complete overview of what one may expect if nanoribbons are cut out\nfrom Pmmn sheets with a view to potential technological applications."
    },
    {
        "anchor": "Long-Lived Valley Polarization of Intra-Valley Trions in Monolayer WSe2: We investigate valley dynamics associated with trions in monolayer tungsten\ndiselenide (WSe2) using polarization resolved two-color pump-probe\nspectroscopy. When tuning the pump and probe energy across the trion resonance,\ndistinct trion valley polarization dynamics are observed as a function of\nenergy and attributed to the intra-valley and inter-valley trions in monolayer\nWSe2. We observe no decay of a near-unity valley polarization associated with\nthe intra-valley trions during ~ 25 ps, while the valley polarization of the\ninter-valley trions exhibits a fast decay of ~ 4 ps. Furthermore, we show that\nresonant excitation is a prerequisite for observing the long-lived valley\npolarization associated with the intra-valley trion. The exceptionally robust\nvalley polarization associated with resonantly created intra-valley trions\ndiscovered here may be explored for future valleytronic applications such as\nvalley Hall effects.",
        "positive": "Protection of Edge transport in Quantum Spin Hall samples: Spin-Symmetry\n  Based General Approach and Examples: Understanding possible mechanisms, which can lead to suppression of helical\nedge transport in Quantum Spin Hall (QSH) systems, attracted huge attention\nright after the first experiments revealing the fragility of the ballistic\nconductance. Despite the very intensive research and the abundance of\ntheoretical models, the fully consistent explanation of the experimental\nresults is still lacking. We systematize various theories of helical transport\nwith the help of the spin conservation analysis which allows one to single out\nsetups with the ballistic conductance being robustly protected regardless of\nthe electron backscattering. First, we briefly review different theories of\nedge transport in the QSH samples with and without the spin axial symmetry of\nthe electrons including those theoretical predictions which are not consistent\nwith the spin conservation analysis and, thus, call for a deeper study. Next,\nwe illustrate the general approach by a detailed study of representative\nexamples. One of them addresses the helical edge coupled to an array of\nHeisenberg-interacting magnetic impurities (MIs) and demonstrates that the\nconductance remains ballistic even if the time-reversal symmetry on the edge is\n(locally) broken but the total spin is conserved. Another example focuses on\nthe effects of the space-fluctuating spin-orbit interaction on the QSH edge. It\nreveals weakness of the protection in several cases, including, e.g., the\npresence of either the U(1)-symmetric, though not fully isotropic, MIs or\ngeneric electron-electron interactions."
    },
    {
        "anchor": "Probing Hybridization of a Single Energy Level Coupled to\n  Superconducting Leads: Electron transport through a quantum dot coupled to superconducting leads\nshows a sharp conductance onset when a quantum dot orbital level crosses the\nsuperconducting coherence peak of one lead. We study superconducting single\nelectron transistors in the weak coupling limit by connecting individual gold\nnanoparticles with aluminum junctions formed by electromigration. We show that\nthe transport features close to the conductance onset threshold can be\naccurately described by the quantum dot levels' hybridization with the leads,\nwhich is strongly enhanced by the divergent density of states at the\nsuperconducting gap edge. This highlights the importance of electron\ncotunneling effects in spectroscopies with superconducting probes.",
        "positive": "Using a qubit to measure photon number statistics of a driven, thermal\n  oscillator: We demonstrate theoretically how photon number statistics of a driven, damped\noscillator at finite temperature can be extracted by measuring the dephasing\nspectrum of a two-level system dispersively coupled to the oscillator; we thus\nextend the work of Dykman (1987) and Gambetta et al. (2006). We carefully\nconsider the fidelity of this scheme-- to what extent does the measurement\nreflect the initial number statistics of the mode? We also derive analytic\nresults for the dephasing of a qubit by a driven, thermal mode, and compare\nresults obtained at different levels of approximation. Our results have\nrelevance both to experiments in circuit cavity QED, as well as to\nnano-electromechanical systems."
    },
    {
        "anchor": "Coherence of polaronic transport in layered metals: Layered systems shows anisotropic transport properties. The interlayer\nconductivity show a general temperature dependence for a wide class of\nmaterials. This can be understood if conduction occurs in two different\nchannels activated at different temperatures. We show that the characteristic\ntemperature dependence can be explained using a polaron model for the\ntransport. The results show an intuitive interpretation in terms of coherent\nand incoherent quasi-particles within the layers. Further, we extract results\nfor the magnetoresistance, thermopower, spectral function and optical\nconductivity for the model and discuss application to experiments.",
        "positive": "Two-way photoeffect-like occupancy dynamics in a single (InGa)As quantum\n  dot: We extend optical spin noise spectroscopy on single (InGa)As quantum dots to\nhigh magnetic fields at which the splitting between the two optical active\nZeeman branches of the positively charged quantum dot trion transition is\nsignificantly larger than the homogeneous line width. Under such conditions,\nthe typical theoretical approximations concerning the decoupling of spin and\ncharge dynamics are in general not valid anymore and the Kerr fluctuations show\nsignificantly richer detuning-dependent features in the spectral region between\nthe two Zeeman branches. A comparison of the experimental data with an extended\ntheory suggests that the typical Auger-recombination can be neglected at high\nmagnetic fields in favour of a probe-laser induced photoeffect that shuffles\nnot only the resident hole out of the quantum dot but also activates\nacceptor-bound holes which recharge the empty quantum dot."
    },
    {
        "anchor": "Impurity scattering on the surface of topological insulator thin films: We address the electronic structure of the surface states of topological\ninsulator thin films with embedded local non-magnetic and magnetic impurities.\nUsing the $T$-matrix expansion of the real space Green's function, we derive\nthe local density of electrons states and corresponding spin resolved\ndensities. We show that the effects of the impurities can be tuned by applying\nan electric field between the surface layers. The emerging magnetic states are\nexpected to play an important role both in ferromagnetic mechanism of magnetic\ntopological insulators as well as in its transport properties. In the case of\nmagnetic impurities, we have categorized the possible cases for different\nspin-directions of the impurities as well as the spin-direction in which the\nspin resolved density of electron states is calculated and related this to the\nspin susceptibility of the system.",
        "positive": "Influence of Landau-level mixing on Wigner crystallization in graphene: Graphene, with its massless linearly-dispersing carriers, in the quantum Hall\nregime provides an instructive comparison with conventional two-dimensional\n(2D) systems in which carriers have a nonzero band mass and quadratic\ndispersion. We investigate the influence of Landau level mixing in graphene on\nWigner crystal states in the $n^\\mathrm{th}$ Landau level obtained using single\nLandau level approximation. We show that the Landau level mixing does not\nqualitatively change the phase diagram as a function of partial filling factor\n$\\nu$ in the $n^\\mathrm{th}$ level. We find that the inter-Landau level mixing,\nquantified by relative occupations of the two Landau levels,\n$\\rho_{n+1}/\\rho_{n}$, oscillates around 2% and, in general, remains small ($<\n4%$) irrespective of the Landau level index $n$. Our results show that the\nsingle Landau level approximation is applicable in high Landau levels, even\nthough the energy gap between the adjacent Landau levels vanishes."
    },
    {
        "anchor": "Broken Inversion Symmetry and Interface-induced Spin-polarization for\n  metal-Weyl semimetal stacked interfaces: Weyl semimetal TaAs, a congenial host to the massless Weyl fermions,\nspontaneously lacks the time-reversal and the inversion symmetry and thus\neffectuates topologically stable Weyl nodes, resembling magnetic monopoles in\nmomentum space. Former experimental analysis had revealed that the near-zero\nspin-polarization of bulk TaAs experiences a boost in presence of\npoint-contacts of non-magnetic metals along with the associated phenomena of\ntip-induced superconductivity, providing the impetus to study the large-area\nstacked interfaces of TaAs with Noble metals like Au and Ag. First-principles\ncalculations on these interfacial systems have manifested an increment of the\ninterface-induced spin-polarization and contact-induced transport\nspin-polarization. In contrast to the single interface, for stacked system, the\nbroken inversion symmetry of the system introduces a z-directional\nband-dispersion resulting in an energetically separated series of Weyl cones.\nThe Weyl cones for TaAs/Ag and TaAs/Au stacked interfaces are observed to be of\ntype-I and type-II nature respectively. Thus, the current study demonstrates\nthe designing of two different types of spin-polarized Weyl systems from\nnon-magnetic metal and type I Weyl components.",
        "positive": "Temperature dependence of the magnon spin diffusion length and magnon\n  spin conductivity in the magnetic insulator yttrium iron garnet: We present a systematic study of the temperature dependence of diffusive\nmagnon spin transport, using a non-local device geometry. In our measurements,\nwe detect spin signals arising from electrical and thermal magnon generation,\nand we directly extract the magnon spin diffusion length $\\lambda_m$ for\ntemperatures from 2 to 293 K. Values of $\\lambda_m$ obtained from electrical\nand thermal generation agree within the experimental error, with\n$\\lambda_m=9.6\\pm0.9$ $\\mu$m at room temperature to a minimum of\n$\\lambda_m=5.5\\pm0.7$ $\\mu$m at 30 K. Using a 2D finite element model to fit\nthe data obtained for electrical magnon generation we extract the magnon spin\nconductivity $\\sigma_m$ as a function of temperature, which is reduced from\n$\\sigma_m=5.1\\pm0.2\\times10^5$ S/m at room temperature to\n$\\sigma_m=0.7\\pm0.4\\times10^5$ S/m at 5 K. Finally, we observe an enhancement\nof the signal originating from thermally generated magnons for low\ntemperatures, where a maximum is observed around $T=7$ K. An explanation for\nthis low temperature enhancement is however still missing and requires\nadditional investigations."
    },
    {
        "anchor": "Excitonic structure of the optical conductivity in MoS$_2$ monolayers: We investigate the excitonic spectrum of MoS$_2$ monolayers and calculate its\noptical absorption properties over a wide range of energies. Our approach takes\ninto account the anomalous screening in two dimensions and the presence of a\nsubstrate, both cast by a suitable effective Keldysh potential. We solve the\nBethe-Salpeter equation using as a basis a Slater-Koster tight-binding model\nparameterized to fit ab initio MoS$_2$ band structure calculations. The\nresulting optical conductivity is in good quantitative agreement with existing\nmeasurements up to ultraviolet energies. We establish that the electronic\ncontributions to the C excitons arise not from states in the vicinity of the\n$\\Gamma$ point, but from a set of $k$-points over extended portions of the\nBrillouin zone. Our results reinforce the advantages of approaches based on\neffective models to expeditiously explore the properties and tunability of\nexcitons in TMD systems.",
        "positive": "ARPES signatures of few-layer twistronic graphenes: Diverse emergent correlated electron phenomena have been observed in twisted\ngraphene layers due to electronic interactions with the moir\\'e superlattice\npotential. Many electronic structure predictions have been reported exploring\nthis new field, but with few momentum-resolved electronic structure\nmeasurements to test them. Here we use angle-resolved photoemission\nspectroscopy (ARPES) to study the twist-dependent ($1^\\circ < \\theta <\n8^\\circ$) electronic band structure of few-layer graphenes, including twisted\nbilayer, monolayer-on-bilayer, and double-bilayer graphene (tDBG). Direct\ncomparison is made between experiment and theory, using a hybrid\n$\\textbf{k}\\cdot\\textbf{p}$ model for interlayer coupling and implementing\nphoton-energy-dependent phase shifts for photo-electrons from consecutive\nlayers to simulate ARPES spectra. Quantitative agreement between experiment and\ntheory is found across twist angles, stacking geometries, and back-gate\nvoltages, validating the models and revealing displacement field induced gap\nopenings in twisted graphenes. However, for tDBG at $\\theta=1.5\\pm0.2^\\circ$,\nclose to the predicted magic-angle of $\\theta=1.3^\\circ$, a flat band is found\nnear the Fermi-level with measured bandwidth of $E_w = 31\\pm5$ meV. Analysis of\nthe gap between the flat band and the next valence band shows significant\ndeviations between experiment ($\\Delta_h=46\\pm5$meV) and the theoretical model\n($\\Delta_h=5$meV), indicative of the importance of lattice relaxation in this\nregime."
    },
    {
        "anchor": "Axial Magnetoelectric Effect in Dirac semimetals: We propose a mechanism to generate a static magnetization via {\\em axial\nmagnetoelectric effect} (AMEE). Magnetization ${\\bf M} \\sim {\\bf\nE}_5(\\omega)\\times {\\bf E}_5^{*}(\\omega)$ appears as a result of the transfer\nof the angular momentum of the axial electric field ${\\bf E}_5(t)$ into the\nmagnetic moment in Dirac and Weyl semimetals. We point out similarities and\ndifferences between the proposed AMEE and a conventional inverse Faraday effect\n(IFE). As an example, we estimated the AMEE generated by circularly polarized\nacoustic waves and find it to be on the scale of microgauss for gigahertz\nfrequency sound. In contrast to a conventional IFE, magnetization rises\nlinearly at small frequencies and fixed sound intensity as well as demonstrates\na nonmonotonic peak behavior for the AMEE. The effect provides a way to\ninvestigate unusual axial electromagnetic fields via conventional magnetometry\ntechniques.",
        "positive": "Andreev reflection in monolayer MoS2: Andreev reflection in a monolayer molybdenum disulfide superconducting-normal\n(S/N) hybrid junction is investigated. We find, by using a modified-Dirac\nHamiltonian and the scattering formalism, that the perfect Andreev reflection\nhappens at normal incidence with $p$-doped S and N regions. The probability of\nthe Andreev reflection and the resulting Andreev conductance, in this system,\nare demonstrated to be large in comparison with corresponding gapped graphene\nstructure. We further investigate the effect of a topological term ($\\beta)$ in\nthe Hamiltonian and show that it results in an enhancement of the Andreev\nconductance with $p$-doped S and N regions, while in the corresponding\nstructure with $n$-doped S region it is strongly reducible in comparison. This\neffect can be explained in terms of the dependence of the Andreev reflection\nprobability on the sign of $\\beta$ and the chemical potential in the\nsuperconducting region."
    },
    {
        "anchor": "Constructing oxide interfaces and heterostructures by atomic\n  layer-by-layer laser molecular beam epitaxy: Advancements in nanoscale engineering of oxide interfaces and\nheterostructures have led to discoveries of emergent phenomena and new\nartificial materials. Combining the strengths of reactive molecular-beam\nepitaxy and pulsed-laser deposition, we show here, with examples of\nSr1+xTi1-xO3+delta, Ruddlesden-Popper phase Lan+1NinO3n+1 (n = 4), and\nLaAl1+yO3(1+0.5y)/SrTiO3 interfaces, that atomic layer-by-layer laser\nmolecular-beam epitaxy (ALL-Laser MBE) significantly advances the state of the\nart in constructing oxide materials with atomic layer precision and control\nover stoichiometry. With ALL-Laser MBE we have produced conducting\nLaAlO3/SrTiO3 interfaces at high oxygen pressures that show no evidence of\noxygen vacancies, a capability not accessible by existing techniques. The\ncarrier density of the interfacial two-dimensional electron gas thus obtained\nagrees quantitatively with the electronic reconstruction mechanism.",
        "positive": "Wavelets spectra of magnetization dynamics in geometry driven magnetic\n  thin layers: Squared cobalt thin layers of different thickness and width were investigated\nby numerical simulations. Using zero-valued externally applied magnetic field\n(geometry driven regime) and different initial conditions the magnetization\ndynamics were examined. The wavelet-based spectral analysis was applied.\nTransient states of different types were identified."
    },
    {
        "anchor": "Universality in scattering by large-scale potential fluctuations in\n  two-dimensional conductors: We study electron propagation through a random array of rare, opaque and\nlarge (compared the de Broglie wavelength of electrons) scatterers. It is shown\nthat for any convex scatterer the ratio of the transport to quantum lifetimes\n\\eta=\\tau_{tr}/\\tau_{tot}$ does not depend on the shape of the scatterer but\nonly on whether scattering is specular or diffuse and on the spatial\ndimensionality (D). In particular, for specular scattering, \\eta is a universal\nconstant determined only by the dimensionality of the system: \\eta = 2 for D =\n3 and \\eta = 3/2 for D = 2. The crossover between classical and quantum regimes\nof scattering is discussed.",
        "positive": "Spin orbit interaction and zitterbewegung in symmetric wells: Recently, we have introduced a novel inter-subband-induced spin-orbit (s-o)\ncoupling [Phys. Rev. Lett. 99, 076603 (2007); cond-mat/0607218] arising in\n\\textit{symmetric} wells with at least two subbands. This new s-o coupling\ngives rise to an usual zitterbewegung -- i.e. the semiconductor analog to the\nrelativistic trembling motion of electrons -- with cycloidal motion without\nmagnetic fields. Here we complement these findings by explicitly deriving\nexpressions for the corresponding zitterbewegung in spin space."
    },
    {
        "anchor": "Long-wavelength optical phonon behavior in uniaxial strained graphene:\n  Role of electron-phonon interaction: We derive the frequency shifts and the broadening of $\\Gamma$ point\nlongitudinal optical (LO) and transverse optical (TO) phonon modes, due to\nelectron-phonon interaction, in graphene under uniaxial strain as a function of\nthe electron density and the disorder amount. We show that, in the absence of a\nshear strain component, such interaction gives rise to a lifting of the\ndegeneracy of the LO and TO modes which contributes to the splitting of the G\nRaman band. The anisotropy of the electronic spectrum, induced by the strain,\nresults in a polarization dependence of the LO and TO modes. This dependence is\nin agreement with the experimental results showing a periodic modulation of the\nRaman intensity of the splitted G peak. Moreover, the anomalous behavior of the\nfrequency shift reported in undeformed graphene is found to be robust under\nstrain.",
        "positive": "Mini Volume Collapse as Evidence for a 3-Body Magnetic Polaron in\n  $Sm_{1-x}Eu_xS$: Samarium sulfide (SmS) is a non-magnetic narrow-gap (0.06 eV) semiconductor\nwhich undergoes a transition to a metallic intermediate valence state at 6.5\nkbar. Europium sulfide (EuS) is a ferromagnetic semiconductor with a Curie\ntemperature of 16K and a gap of 1.6 eV. Here we present a study of the lattice\nconstant, magnetic susceptibility, and resistivity of the substitution series\n$Sm_{1-x}Eu_xS$ for 0 < x < 1. We observe a smooth interpolation of magnetic\nand transport behavior across the series, consistent with a virtual crystal\nscenario and Vegard's law. Surprisingly, however, the lattice constant deviates\nbelow Vegard's law in a manner that suggests parametric control of the Sm-Sm\ndistance by the Eu moment in the manner of a magnetic polaron."
    },
    {
        "anchor": "Relaxation Effects in Twisted Bilayer Graphene: a Multi-Scale Approach: We present a multi-scale density functional theory (DFT) informed molecular\ndynamics and tight-binding (TB) approach to capture the interdependent atomic\nand electronic structures of twisted bilayer graphene. We calibrate the flat\nband magic angle to be at $\\theta_{\\rm M} = 1.08^{\\circ}$ by rescaling the\ninterlayer tunneling for different atomic structure relaxation models as a way\nto resolve the indeterminacy of existing atomic and electronic structure models\nwhose predicted magic angles vary widely between $0.9^\\circ \\sim 1.3^\\circ$.\nThe interatomic force fields are built using input from various stacking and\ninterlayer distance dependent DFT total energies including the exact exchange\nand random phase approximation (EXX+RPA). We use a Fermi velocity of\n$\\upsilon_{\\rm F} \\simeq 10^{6}$~m/s for graphene that is enhanced by about\n$\\sim 15\\%$ over the local density approximation (LDA) values. Based on this\natomic and electronic structure model we obtain high-resolution spectral\nfunctions comparable with experimental angle-resolved photoemission spectra\n(ARPES). Our analysis of the interdependence between the atomic and electronic\nstructures indicates that the intralayer elastic parameters compatible with the\nDFT-LDA, which are stiffer by $\\sim$30\\% than widely used reactive empirical\nbond order force fields, can combine with EXX+RPA interlayer potentials to\nyield the magic angle at $\\sim 1.08^{\\circ}$ without further rescaling of the\ninterlayer tunneling.",
        "positive": "Complete $T_c$ suppression and N\u00e9el triplets-mediated exchange in\n  antiferromagnet-superconductor-antiferromagnet trilayers: An antiferromagnetic insulator (AFI) bearing a compensated interface to an\nadjacent conventional superconductor (S) has recently been predicted to\ngenerate N\\'eel triplet Cooper pairs, whose amplitude alternates sign in space.\nHere, we theoretically demonstrate that such N\\'eel triplets enable control of\nthe superconducting critical temperature in an S layer via the angle between\nthe N\\'eel vectors of two enclosing AFI layers. This angle dependence changes\nsign with the number of S monolayers providing a distinct signature of the\nN\\'eel triplets. Furthermore, we show that the latter mediate a similarly\ndistinct exchange interaction between the two AFIs' N\\'eel vectors."
    },
    {
        "anchor": "Interference of electrons in backscattering through a quantum point\n  contact: Scanning gate microscopy is used to locally investigate electron transport in\na high-mobility two-dimensional electron gas formed in a GaAs/AlGaAs\nheterostructure. Using quantum point contacts (QPC) we observe branches caused\nby electron backscattering decorated with interference fringes similar to\nprevious observations by Topinka et al. We investigate the branches at\ndifferent points of a conductance plateau as well as between plateaus, and\ndemonstrate that the most dramatic changes in branch pattern occur at the\nlow-energy side of the conductance plateaus. The branches disappear at magnetic\nfields as low as 50 mT demonstrating the importance of backscattering for the\nobservation of the branching effect. The spacing between the interference\nfringes varies by more than 50% for different branches across scales of\nmicrons. Several scenarios are discussed to explain this observation.",
        "positive": "From stochastic single atomic switch to nanoscale resistive memory\n  device: Solid state ionic conductors are good candidates for the next generation of\nnonvolatile computer memory elements. Such devices have to show reproducible\nresistance switching at reasonable voltage and current values even if scaled\ndown to the nanometer sizes. Here we study the switching characteristics of\nnanoscale junctions created between a tungsten tip and a silver film covered by\na thin ionic conductor layer. Atomic-sized junctions show spectacular current\ninduced switching characteristics, but both the magnitude of the switching\nvoltage and the direction of the switching vary randomly for different\njunctions. In contrast, for somewhat larger junctions with diameters of a few\nnanometers a well defined, reproducible switching behavior is observed which is\nassociated with the formation and destruction of nanoscale channels in the\nionic conductor surface layer. Our results define a low size limit of 3 nm for\nreliable ionic nano-switches, which is well below the resolution of recent\nlithographic techniques."
    },
    {
        "anchor": "Chiral-mediated entanglement in an Aharonov-Bohm ring: We study the orbital entanglement in a biased Aharonov-Bohm ring connected in\na four-terminal setup. We find that the concurrence achieves a maximum when the\nmagnetic flux B coincides with an integer number of a half flux quantum 0 /2.\nWe show that this behavior is a consequence of the existence of degenerate\nstates of the ring having opposite chirality. We also analyze the behavior of\nthe noise as a function of and discuss the reliability of this quantity as\nevidence of entanglement.",
        "positive": "Dynamical photo-induced electronic properties of molecular junctions: Nanoscale molecular-electronic devices and machines are emerging as promising\nfunctional elements, naturally flexible and efficient, for next generation\ntechnologies. A deeper understanding of carrier dynamics in molecular junctions\nis expected to benefit many fields of nanoelectronics and power-devices. We\ndetermine time-resolved charge current flowing at donor- acceptor interface in\nmolecular junctions connected to metallic electrodes by means of quantum\ntransport simulations. The current is induced by the interaction of the donor\nwith a Gaussian-shape femtosecond laser pulse. Effects of the molecular\ninternal coupling, metal- molecule tunneling and light-donor coupling on\nphotocurrent are discussed. We then examine the junction working through the\ntime-resolved donor density of states. Non-equilibrium reorganization of\nhybridized molecular orbitals through the light-donor interaction gives rise to\ntwo phenomena: the dynamical Rabi shift and the appearance of Floquet-like\nstates. Such insights into the dynamical photoelectronic structure of molecules\nare of strong interest for ultrafast spectroscopy, and open avenues toward the\npossibility of analyzing and controlling the internal properties of quantum\nnanodevices with pump-push photocurrent spectroscopy."
    },
    {
        "anchor": "Topological insulator based spin valve devices: evidence for spin\n  polarized transport of spin-momentum-locked topological surface states: Spin-momentum helical locking is one of the most important properties of the\nnontrivial topological surface states (TSS) in 3D topological insulators (TI).\nIt underlies the iconic topological protection (suppressing elastic\nbackscattering) of TSS and is foundational to many exotic physics (eg.,\nmajorana fermions) and device applications (eg., spintronics) predicted for\nTIs. Based on this spin-momentum locking, a current flowing on the surface of a\nTI would be spin-polarized in a characteristic in-plane direction perpendicular\nto the current, and the spin-polarization would reverse when the current\ndirection reverses. Observing such a spin-helical current in transport\nmeasurements is a major goal in TI research and applications. We report\nspin-dependent transport measurements in spin valve devices fabricated from\nexfoliated thin flakes of Bi2Se3 (a prototype 3D TI) with ferromagnetic (FM) Ni\ncontacts. Applying an in-plane magnetic (B) field to polarize the Ni contacts\nalong their easy axis, we observe an asymmetry in the hysteretic\nmagnetoresistance (MR) between opposite B field directions. The polarity of the\nasymmetry in MR can be reversed by reversing the direction of the DC current.\nThe observed asymmetric MR can be understood as a spin-valve effect between the\ncurrent-induced spin polarization on the TI surface (due to\nspin-momentum-locking of TSS) and the spin-polarized ferromagnetic contacts.\nOur results provide a direct transport evidence for the spin helical current in\nTSS.",
        "positive": "Engineering Superposition States and Tailored Probes for Nano-resonators\n  Via Open-Loop Control: We show that a nano-resonator can be prepared in mesoscopic-superposition\nstates merely by monitoring a qubit coupled to the square of the resonators\nposition. This works for thermal initial states, and does not require a\nthird-order nonlinearity. The required coupling can be generated using a simple\nopen-loop control protocol, obtained with optimal control theory. We simulate\nthe complete preparation process, including environmental noise. Our results\nindicate the power of open-loop control for state-engineering and measurement\nin quantum nano-systems."
    },
    {
        "anchor": "Electron polarization function and plasmons in metallic armchair\n  graphene nanoribbons: We calculate the polarization function of Dirac fermions in metallic armchair\ngraphene nanoribbons for an arbitrary temperature and doping. We find that at\nfinite temperatures due to the phase space redistribution among inter-band and\nintra-band electronic transitions in the conduction and valence bands, the full\npolarization function becomes independent of the temperature and the position\nof the chemical potential. As a result, for a given width of nanoribbons there\nexists a single plasmon mode, with the energy dispersion determined by the\ngraphene's fine structure constant. In Coulomb-coupled nanoribbons, this\nplasmon splits into the basic in-phase and out-of-phase plasmon modes, with the\nsplitting energy determined additionally by the inter-ribbon spacing.",
        "positive": "Large tunable intrinsic gap in rhombohedral-stacked tetralayer graphene: In rhombohedral-stacked few-layer graphene, the very flat energy bands near\nthe charge neutrality point are unstable to electronic interactions, giving\nrise to states with spontaneous broken symmetries. Using transport measurements\non suspended rhombohedral-stacked tetralayer graphene, we observe an insulating\nground state with a large interaction-induced gap up to 80 meV. This gapped\nstate can be enhanced by a perpendicular magnetic field, and suppressed by an\ninterlayer potential, carrier density, or a critical temperature of ~ 40 K."
    },
    {
        "anchor": "Topology of one dimensional quantum systems out of equilibrium: We study the topological properties of one dimensional systems undergoing\nunitary time evolution. We show that symmetries possessed both by the initial\nwavefunction and by the Hamiltonian at all times may not be present in the\ntime-dependent wavefunction -- a phenomenon which we dub \"dynamically-induced\nsymmetry breaking\". This leads to the possibility of a time-varying bulk index\nafter quenching within non-interacting gapped topological phases. The\nconsequences are observable experimentally through particle transport\nmeasurements. With reference to the entanglement spectrum, we explain how the\ntopology of the wavefunction can change out of equilibrium, both for\nnon-interacting fermions and for symmetry-protected topological phases\nprotected by antiunitary symmetries.",
        "positive": "Interplay of Dirac nodes and Volkov-Pankratov surface states in\n  compressively strained HgTe: Preceded by the discovery of topological insulators, Dirac and Weyl\nsemimetals have become a pivotal direction of research in contemporary\ncondensed matter physics. While easily accessible from a theoretical viewpoint,\nthese topological semimetals pose a serious challenge in terms of experimental\nsynthesis and analysis to allow for their unambiguous identification. In this\nwork, we report on detailed transport experiments on compressively strained\nHgTe. Due to the superior sample quality in comparison to other topological\nsemimetallic materials, this enables us to resolve the interplay of topological\nsurface states and semimetallic bulk states to an unprecedented degree of\nprecision and complexity. As our gate design allows us to precisely tune the\nFermi level at the Weyl and Dirac points, we identify a magnetotransport regime\ndominated by Weyl/Dirac bulk state conduction for small carrier densities and\nby topological surface state conduction for larger carrier densities. As such,\nsimilar to topological insulators, HgTe provides the archetypical reference for\nthe experimental investigation of topological semimetals."
    },
    {
        "anchor": "Chebyshev Polynomial Method to Landauer-B\u00fcttiker Formula of Quantum\n  Transport in Nanostructures: Landauer-B\\\"uttiker formula describes the electronic quantum transports in\nnanostructures and molecules. It will be numerically demanding for simulations\nof complex or large size systems due to, for example, matrix inversion\ncalculations. Recently, Chebyshev polynomial method has attracted intense\ninterests in numerical simulations of quantum systems due to the high\nefficiency in parallelization, because the only matrix operation it involves is\njust the product of sparse matrices and vectors. Many progresses have been made\non the Chebyshev polynomial representations of physical quantities for isolated\nor bulk quantum structures. Here we present the Chebyshev polynomial method to\nthe typical electronic scattering problem, the Landauer-B\\\"uttiker formula for\nthe conductance of quantum transports in nanostructures. We first describe the\nfull algorithm based on the standard bath kernel polynomial method (KPM). Then,\nwe present two simple butefficient improvements. One of them has a time\nconsumption remarkably less than the direct matrix calculation without KPM.\nSome typical examples are also presented to illustrate the numerical\neffectiveness.",
        "positive": "Quantum Hall conductance of two-terminal graphene devices: Measurement and theory of the two-terminal conductance of monolayer and\nbilayer graphene in the quantum Hall regime are compared. We examine features\nof conductance as a function of gate voltage that allow monolayer, bilayer, and\ngapped samples to be distinguished, including N-shaped distortions of quantum\nHall plateaus and conductance peaks and dips at the charge neutrality point.\nGenerally good agreement is found between measurement and theory. Possible\norigins of discrepancies are discussed."
    },
    {
        "anchor": "Spin torque due to diffusive spin current in magnetic texture: We present a microscopic theory of spin torque due to diffusive spin currents\ninduced by spin accumulation. The obtained expression is a natural extension of\nthe existing one due to 'local' spin currents associated with ordinary electric\ncurrents, and is the reciprocal of the spin motive force which induces charge\naccumulation as studied recently [J. Shibata and H. Kohno, Phys. Rev. B84,\n184408 (2011)]. The result is applied to a domain wall motion in a nonlocal\nspin injection system, and the torque and force due to diffusive spin current\nare evaluated.",
        "positive": "Scale invariance of a diodelike tunnel junction: We measure the current vs voltage (I-V) characteristics of a diodelike tunnel\njunction consisting of a sharp metallic tip placed at a variable distance d\nfrom a planar collector and emitting electrons via electric-field assisted\nemission. All curves collapse onto one single graph when I is plotted as a\nfunction of the single scaling variable Vd^{-\\lambda}, d being varied from a\nfew mm to a few nm, i.e., by about six orders of magnitude. We provide an\nargument that finds the exponent {\\lambda} within the singular behavior\ninherent to the electrostatics of a sharp tip. A simulation of the tunneling\nbarrier for a realistic tip reproduces both the scaling behavior and the small\nbut significant deviations from scaling observed experimentally."
    },
    {
        "anchor": "Nanoscale Skyrmions on a Square Atomic Lattice: Spin-polarized scanning tunneling microscopy has been applied to study\nnon-collinear spin textures of a Mn monolayer on a four-fold symmetric W(001)\nsubstrate revealing a zero-field spin spiral ground state and two different\ntypes of rotational domain walls. With an applied magnetic field of 9 T, we\nobserve a coexistence of the spin spiral and the skyrmion phase, even though a\nprevious theoretical study reported that the phase transition occurs at 18 T.\nThe skyrmions show a roughly hexagonal arrangement despite the square lattice\nsymmetry of the W(001) substrate. Based on a reduced set of energy parameters,\nwe are able to describe the experimental findings and to analyze the\ntopological properties of the rotational domain walls.",
        "positive": "Two-Dimensional Optical Spectroscopy of Excitons in Semiconductor\n  Quantum Wells: Liouville-space pathway analysis: We demonstrate how dynamic correlations of heavy-hole and light-hole excitons\nin semiconductor quantum wells may be investigated by two dimensional\ncorrelation spectroscopy (2DCS). The coherent response to three femtosecond\noptical pulses is predicted to yield cross (off-diagonal) peaks that contain\ndirect signatures of many-body two-exciton correlations. Signals generated at\nvarious phase-matching directions are compared."
    },
    {
        "anchor": "Edge states and integer quantum Hall effect in topological insulator\n  thin films: The integer quantum Hall effect is a topological state of quantum matter in\ntwo dimensions, and has recently been observed in three-dimensional topological\ninsulator thin films. Here we study the Landau levels and edge states of\nsurface Dirac fermions in topological insulators under strong magnetic field.\nWe examine the formation of the quantum plateaux of the Hall conductance and\nfind two different patterns, in one pattern the filling number covers all\nintegers while only odd integers in the other. We focus on the quantum plateau\nclosest to zero energy and demonstrate the breakdown of the quantum spin Hall\neffect resulting from structure inversion asymmetry. The phase diagrams of the\nquantum Hall states are presented as functions of magnetic field, gate voltage\nand chemical potential. This work establishes an intuitive picture of the edge\nstates to understand the integer quantum Hall effect for Dirac electrons in\ntopological insulator thin films.",
        "positive": "Complete Spin and Valley Polarization by Total External Reflection from\n  Potential Barriers in Bilayer Graphene and Monolayer Transition Metal\n  Dichalcogenides: It is shown that potential barriers in bilayer graphene (BLG) and monolayer\ntransition metal dichalcogenides (TMDs) can split a valley unpolarized incident\ncurrent into reflected and transmitted currents with opposite valley\npolarization. Valley asymmetric transmission inevitably occurs because of the\nlow symmetry of the total Hamiltonian and when total external reflection occurs\nthe transmission is 100% valley polarized in BLG and 100% spin and valley\npolarized in TMDs, except for exponentially small corrections. By adjusting the\npotential, 100% polarization can be obtained regardless of the crystallographic\norientation of the barrier. A valley polarizer can be realized by arranging for\na collimated beam of carriers to be incident on a barrier within the range of\nangles for total external reflection. The transmission coefficients of barriers\nwith a relative rotation of $\\pm\\pi/3$ are related by symmetry. This allows two\nbarriers to be used to demonstrate that the current is valley polarized. A\nsoft-walled potential is used to model the barrier and the method used to find\nthe transmission coefficients is explained. In the case of monolayer TMDs, a\n4-band k.p Hamiltonian is used and the k.p parameters are obtained by fitting\nto ab-initio band structures."
    },
    {
        "anchor": "Engineering electron wavefunctions in asymmetrically confined quasi\n  one-dimensional structures: We present results on electron transport in quasi-one dimensional (1D)\nquantum wires in GaAs/AlGaAs heterostructures obtained using an asymmetric\nconfinement potential. The variation of the energy levels of the spatially\nquantized states is followed from strong confinement through weak confinement\nto the onset of two-dimensionality. An anticrossing of the initial ground and\nfirst excited states is found as the asymmetry of the potential is varied\ngiving rise to two anticrossing events which occur on either side of symmetric\nconfinement. We present results analysing this behaviour and showing how it can\nbe affected by the inhomogeneity in background potential. The use of an\nenhanced source-drain voltage to alter the energy levels is shown to be a\nsignificant validation of the analysis by showing the formation of double rows\nof electrons which correlate with the anticrossing.",
        "positive": "Non-perturbative approach to backscattering off a dynamical impurity in\n  1D Fermi systems: We investigate the problem of backscattering off a time-dependent impurity in\na one-dimensional electron gas. By combining the Schwinger-Keldysh method with\nan adiabatic approximation in order to deal with the corresponding out of\nequilibrium Dirac equation, we compute the total energy density (TED) of the\nsystem. We show how the free fermion TED is distorted by the backscattering\namplitude and the geometry of the impurity."
    },
    {
        "anchor": "Coherent Destruction of Tunneling in a Two Electron Double Quantum Dot:\n  Interplay of Coulomb interaction, spin-orbit interaction and AC field: We study a double quantum dot system with two interacting electrons in the\npresence of a time-dependent periodic (AC) electric field and spin-orbit\ninteraction. We focus on the phenomenon of Coherent Destruction of Tunneling\n(CDT) for an initially localized state. Because of the periodicity introduced\nby the AC field we use Floquet theory to find quasi energies with their\ncrossing and anti-crossing points corresponding to CDT . We observe that the AC\nfield rescales the spin orbit and hopping amplitudes in terms of Bessel\nfunctions. The zeros of the Bessel functions are of the form of a ratio of AC\nfield strength to its frequency and quasi energies at these points form\nanti-crossings in our case. We first prepare the system in a triplet state and\nstudy the evolution of its probability in the presence of spin-orbit\ninteraction alone. We observe an oscillatory behavior which indicates spin flip\ntransitions. However when the AC field is turned on the probability\noscillations are highly suppressed at anti-crossing points leading to\nlocalization of initial state and the state retains its memory of spin even in\nthe presence of spin flip interaction.",
        "positive": "Spintronics-compatible approach to solving maximum satisfiability\n  problems with probabilistic computing, invertible logic and parallel\n  tempering: The search of hardware-compatible strategies for solving NP-hard\ncombinatorial optimization problems (COPs) is an important challenge of today s\ncomputing research because of their wide range of applications in real world\noptimization problems. Here, we introduce an unconventional scalable approach\nto face maximum satisfiability problems (Max-SAT) which combines probabilistic\ncomputing with p-bits, parallel tempering, and the concept of invertible logic\ngates. We theoretically show the spintronic implementation of this approach\nbased on a coupled set of Landau-Lifshitz-Gilbert equations, showing a\npotential path for energy efficient and very fast (p-bits exhibiting ns time\nscale switching) architecture for the solution of COPs. The algorithm is\nbenchmarked with hard Max-SAT instances from the 2016 Max-SAT competition\n(e.g., HG-4SAT-V150-C1350-1.cnf which can be described with 2851 p-bits),\nincluding weighted Max-SAT and Max-Cut problems."
    },
    {
        "anchor": "Engineering the speedup of quantum tunneling in Josephson systems via\n  dissipation: We theoretically investigate the escape rate occurring via quantum tunneling\nin a system affected by tailored dissipation. Specifically, we study the\nenvironmental assisted quantum tunneling of the superconducting phase in a\ncurrent-biased Josephson junction. We consider Ohmic resistors inducing\ndissipation both in the phase and in the charge of the quantum circuit. We find\nthat the charge dissipation leads to an enhancement of the quantum escape rate.\nThis effect appears already in the low Ohmic regime and also occurs in the\npresence of phase dissipation that favors localization. Inserting realistic\ncircuit parameters, we address the question of its experimental observability\nand discuss suitable parameter spaces for the observation of the enhanced rate.",
        "positive": "Asymmetric Landau bands due to spin-orbit coupling: We show that the Landau bands obtained in a two-dimensional lateral\nsemiconductor superlattice with spin-orbit coupling (SOC) of the\nRashba/Dresselhaus type, linear in the electron momentum, placed in a tilted\nmagnetic field, do not follow the symmetry of the spatial modulation. Moreover,\nthis phenomenology is found to depend on the relative tilt of magnetic field\nand on the SOC type: a) when only Rashba SOC exists and the magnetic field is\ntilted in the direction of the superlattice b) Dresselhaus SOC exists and the\nmagnetic field is tilted in the direction perpendicular to the superlattice.\nConsequently, measurable properties of the modulated system become anisotropic\nin a tilted magnetic field when the field is conically rotated around the $z$\naxis, at a fixed polar angle, as we demonstrate by calculating the resistivity\nand the magnetization."
    },
    {
        "anchor": "Three-dimensional skyrmionic cocoons in magnetic multilayers: Three-dimensional (3D) topological spin textures emerge as promising\nquasi-particles for encoding information in future spintronic devices. The\nthird dimension provides more malleability regarding their magnetic properties\nas well as more flexibility for potential applications. However, the\nstabilization and characterization of such quasi-particles in easily\nimplementable systems remain a work in progress. Here we observe a new type of\n3D magnetic textures that we called skyrmionic cocoons that sits in the\ninterior of magnetic thin films multilayers and possesses a characteristic\nellipsoidal shape. Interestingly, these cocoons can coexist with more standard\n`tubular' skyrmions going through all the multilayer as evidenced by the\nexistence of two very different contrasts in the MFM images recorded at room\ntemperature. The presence of these novel skyrmionic textures as well as the\nunderstanding of their layer resolved chiral and topological properties have\nbeen investigated by micromagnetic simulations. In order to experimentally\nstabilize the combination of 3D skyrmion tubes and cocoons, we have elaborated\nmetallic multilayers in which the magnetic properties, notably the anisotropy,\nof the magnetic films in the stacks is varied depending on their vertical\nposition. Finally, in complement to the magnetic imaging, we also measure the\nmagneto-resistive response of the multilayers as a function of the magnetic\nfield, and succeed to fit its evolution using the 3D micromagnetic simulations\nas inputs for the magnetic configuration. The excellent agreement that is\nreached brings additional evidence of the presence of skyrmionic cocoons that\nhence can be electrically detected.",
        "positive": "Quantum transport in mesoscopic ring structures: Effects of impurities,\n  long-range hopping and interactions: In the present review we make a comprehensive analysis of our understanding\non electron transport in mesoscopic single-channel rings and multi-channel\ncylinders within a tight-binding framework. A spectacular mesoscopic phenomenon\nwhere a non-decaying current circulates in a small conducting loop is observed\nupon the application of an Aharonov-Bohm flux $\\phi$. To understand its\nbehavior one has to focus attention on the interplay of quantum phase\ncoherence, electron-electron correlation and disorder. This is a highly\nchallenging problem and here we address it for some simple loop geometries with\ntheir detailed energy band structures to get an entire picture at the\nmicroscopic level. The behavior of low-field magnetic response of persistent\ncurrent and its temperature dependence are also discussed."
    },
    {
        "anchor": "Composite topological structure of domain walls in synthetic\n  antiferromagnets: We experimentally study the structure and dynamics of magnetic domains in\nsynthetic antiferromagnets based on Co/Ru/Co films. Dramatic effects arise from\nthe interaction among the topological defects comprising the dual domain walls\nin these structures. Under applied magnetic fields, the dual domain walls\npropagate following the dynamics of bi-meronic (bi-vortex/bi-antivortex)\ntopological defects built in the walls. Application of an external field\ntriggers a rich dynamical response: The propagation depends on mutual\norientation and chirality of bi-vortices and bi-antivortices in the domain\nwalls. For certain configurations, we observe sudden jumps of composite domain\nwalls in increasing field, which are associated with the decay of composite\nskyrmions. These features allow for enhanced control of domain-wall motion in\nsynthetic antiferromagnets with the potential of employing them as information\ncarriers in future logic and storage devices.",
        "positive": "Ratchet effect enhanced by plasmons: Ratchet effect -- a {\\it dc} current induced by the electromagnetic wave\nimpinging on the spatially modulated two-dimensional (2D) electron liquid --\noccurs when the wave amplitude is spatially modulated with the same wave vector\nas the 2D liquid but is shifted in phase. The analysis within the framework of\nthe hydrodynamic model shows that the ratchet current is dramatically enhanced\nin the vicinity of the plasmonic resonances and has nontrivial polarization\ndependence. In particular, for circular polarization, the current component,\nperpendicular to the modulation direction, changes sign with the inversion of\nthe radiation helicity. Remarkably, in the high-mobility structures, this\ncomponent might be much larger than the the current component in the modulation\ndirection. We also discuss the non-resonant regime realized in dirty systems,\nwhere the plasma resonances are suppressed, and demonstrate that the\nnon-resonant ratchet current is controlled by the Maxwell relaxation in the 2D\nliquid."
    },
    {
        "anchor": "Laplacian-Level Quantum Hydrodynamic Theory for Plasmonics: An accurate description of the optical response of subwavelength metallic\nparticles and nanogap structures is a key problem of plasmonics. Quantum\nhydrodynamic theory (QHT) has emerged as a powerful method to calculate the\noptical response of metallic nanoparticles (NPs) since it takes into account\nnonlocality and spill-out effects. Nevertheless, the absorption spectra of\nmetallic NPs obtained with conventional QHT, i.e., incorporating Thomas-Fermi\n(TF) and von Weizs\\\"acker (vW) kinetic energy (KE) contributions, can be\naffected by several spurious resonances at energies higher than the main\nlocalized surface plasmon (LSP). These peaks are not present in reference\ntime-dependent density-functional-theory (TD-DFT) spectra, where, instead, only\na broad shoulder exists. Moreover, we show here that these peaks incorrectly\nreduce the LSP peak intensity and have a strong dependence on the simulation\ndomain size so that a proper calculation of QHT absorption spectra can be\nproblematic. In this article, we introduce a more general QHT method accounting\nfor KE contributions depending on the Laplacian of the electronic density\n($q$), thus, beyond the gradient-only dependence of the TFvW functional. We\nshow that employing a KE functional with a term proportional to $q^2$ results\nin an absorption spectrum free of spurious peaks, with LSP resonance of correct\nintensity and numerically stable Bennett state. Finally, we present a novel\nLaplacian-level KE energy functional that is very accurate for the description\nof the optical properties of NPs with different sizes as well as for dimers.",
        "positive": "Perfect one-dimensional interface states in a twisted stack of\n  three-dimensional topological insulators: We theoretically study the electronic structure of interface states in\ntwisted stacks of three-dimensional topological insulators. When the center of\nthe surface Dirac cone is located at a midpoint of a side of BZ boundary, we\nfind that an array of nearly-independent one-dimensional channels is formed by\nthe interface hybridization of the surface states, even when the moir\\'{e}\npattern itself is isotropic. The two counter-propagating channels have opposite\nspin polarization, and they are robust against scattering by spin-independent\nimpurities. The coupling between the parallel channels can be tuned by the\ntwist angle.The unique 1D states can be understood as effective Landau levels\nwhere the twist angle works as a fictitious magnetic field."
    },
    {
        "anchor": "Acoustic realization of projective mirror Chern insulators: Symmetry plays a key role in classifying topological phases. Recent theory\nshows that in the presence of gauge fields, the algebraic structure of\ncrystalline symmetries needs to be projectively represented, which enables\nunprecedented topological band physics. Here, we report a concrete acoustic\nrealization of mirror Chern insulators by exploiting the concept of projective\nsymmetry. More specifically, we introduce a simple but universal recipe for\nconstructing projective mirror symmetry, and conceive a minimal model for\nachieving the projective symmetry-enriched mirror Chern insulators. Based on\nour selective-excitation measurements, we demonstrate unambiguously the\nprojective mirror eigenvalue-locked topological nature of the bulk states and\nassociated chiral edge states. More importantly, we extract the non-abelian\nBerry curvature and identify the mirror Chern number directly, as conclusive\nexperimental evidence for this exotic topological phase. All experimental\nresults agree well with the theoretical predictions. Our findings will shine\nnew light on the topological systems equipped with gauge fields.",
        "positive": "Berry curvature induced magnetotransport in 3D noncentrosymmetric metals: We study the magnetoelectric and magnetothermal transport properties of\nnoncentrosymmetric metals using semiclassical Boltzmann transport formalism by\nincorporating the effects of Berry curvature and orbital magnetic moment. These\neffects impart quadratic-B dependence to the magnetoelectric and magnetothermal\nconductivities, leading to intriguing phenomena such as planar Hall effect,\nnegative magnetoresistance, planar Nernst effect and negative Seebeck effect.\nThe transport coefficients associated with these effects show the usual\noscillatory behavior with respect to the angle between the applied electric\nfield and magnetic field. The bands of noncentrosymmetric metals are split by\nRashba spin-orbit coupling except at a band touching point. For Fermi energy\nbelow (above) the band touching point, giant (diminished) negative\nmagnetoresistance is observed. This difference in the nature of\nmagnetoresistance is related to the magnitudes of the velocities, Berry\ncurvature and orbital magnetic moment on the respective Fermi surfaces, where\nthe orbital magnetic moment plays the dominant role. The absolute\nmagnetoresistance and planar Hall conductivity show a decreasing (increasing)\ntrend with Rashba coupling parameter for Fermi energy below (above) the band\ntouching point."
    },
    {
        "anchor": "Broadband microwave spectroscopy of semiconductor nanowire-based\n  Cooper-pair transistors: The Cooper-pair transistor (CPT), a small superconducting island enclosed\nbetween two Josephson weak links, is the atomic building block of various\nsuperconducting quantum circuits. Utilizing gate-tunable semiconductor channels\nas weak links, the energy scale associated with the Josephson tunneling can be\nchanged with respect to the charging energy of the island, tuning the extent of\nits charge fluctuations. Here, we directly demonstrate this control by mapping\nthe energy level structure of a CPT made of an indium arsenide nanowire (NW)\nwith a superconducting aluminum shell. We extract the device parameters based\non the exhaustive modeling of the quantum dynamics of the phase-biased nanowire\nCPT and directly measure the even-odd parity occupation ratio as a function of\nthe device temperature, relevant for superconducting and prospective\ntopological qubits.",
        "positive": "A Microscopic Lattice for Two-dimensional Dipolar Excitons: We report a two-dimensional artificial lattice for dipolar excitons confined\nin a GaAs double quantum well. Exploring the regime of large fillings per\nlattice site, we verify that the lattice depth competes with the magnitude of\nexcitons repulsive dipolar interactions to control the degree of localisation\nin the lattice potential. Moreover, we show that dipolar excitons radiate a\nnarrow-band photoluminescence, with a spectral width of a few hundreds of\nmicro-eV at 340 mK, in both localised and delocalised regimes. This makes our\ndevice suitable for explorations of dipolar excitons quasi-condensation in a\nperiodic potential."
    },
    {
        "anchor": "Electronic States and Light Absorption in a Cylindrical Quantum Dot\n  Having Thin Falciform Cross Section: Energy level structure and direct light absorption in a cylindrical quantum\ndot, having thin falciform cross section, are studied within the framework of\nthe adiabatic approximation. An analytical expression for the energy spectrum\nof the particle is obtained. For the one-dimensional fast subsystem, an\noscillatory dependence of the wave function amplitude on the cross section\nparameters is revealed. For treatment of the slow subsystem, parabolic and\nmodified Poschl-Teller effective potentials are used. It is shown that the\nlow-energy levels of the spectrum are equidistant. In the strong quantization\nregime, the absorption coefficient and edge frequencies are calculated.\nSelection rules for the corresponding quantum transitions are obtained.",
        "positive": "Many-body effects in magnetic inelastic electron tunneling spectroscopy: Magnetic inelastic electron tunneling spectroscopy (IETS) shows sharp\nincreases in conductance when a new conductance channel associated to a change\nin magnetic structure is open. Typically, the magnetic moment carried by an\nadsorbate can be changed by collision with a tunneling electron; in this\nprocess the spin of the electron can flip or not. A previous one-electron\ntheory [Phys. Rev. Lett. {\\bf 103}, 176601 (2009)] successfully explained both\nthe conductance thresholds and the magnitude of the conductance variation. The\nelastic spin flip of conduction electrons by a magnetic impurity leads to the\nwell known Kondo effect. In the present work, we compare the theoretical\npredictions for inelastic magnetic tunneling obtained with a one-electron\napproach and with a many-body theory including Kondo-like phenomena. We apply\nour theories to a singlet-triplet transition model system that contains most of\nthe characteristics revealed in magnetic IETS. We use two self-consistent\ntreatments (non-crossing approximation and self-consistent ladder\napproximation). We show that, although the one-electron limit is properly\nrecovered, new intrinsic many-body features appear. In particular, sharp peaks\nappear close to the inelastic thresholds; these are not localized exactly at\nthresholds and could influence the determination of magnetic structures from\nIETS experiments.Analysis of the evolution with temperature reveals that these\nmany-body features involve an energy scale different from that of the usual\nKondo peaks. Indeed, the many-body features perdure at temperatures much larger\nthan the one given by the Kondo energy scale of the system."
    },
    {
        "anchor": "Spin Polarizations at and about the Lowest Filled Landau Level: The spin polarization versus temperature at or near a fully filled lowest\nLandau level is explored for finite-size systems in a periodic rectangular\ngeometry. Our results at $\\nu=1$ which also include the finite-thickness\ncorrection are in good agreement with the experimental results. We also find\nthat the interacting electron system results are in complete agreement with the\nresults of the sigma model, i.e., skyrmions on a torus have a topological\ncharge of $Q \\ge 2$ and the Q=1 solution is like a single spin-flip excitation.\nOur results therefore provide direct evidence for the skyrmionic nature of the\nexcitations at this filling factor.",
        "positive": "Hamiltonian approach to the torsional anomalies and its dimensional\n  ladder: Torsion can cause various anomalies in various dimensions, including the\n$\\left(3+1\\right)$-dimensional $[(3+1)D]$ Nieh-Yan anomaly, the\n$\\left(2+1\\right)$D Hughes-Leigh-Fradkin (HLF) parity anomaly, and the\n$\\left(3+1\\right)$D, $\\left(1+1\\right)$D chiral energy-momentum anomaly. We\nstudy these anomalies from the Hamiltonian approach. We derive the\n$\\left(1+1\\right)$D chiral energy-momentum anomaly from the single-body\nHamiltonian. We then show how other torsional anomalies can be related to the\n$\\left(1+1\\right)$D chiral energy-momentum anomaly in a straightforward way.\nFinally, the Nieh-Yan anomaly and the $\\left(3+1\\right)$D chiral\nenergy-momentum anomaly are obtained from the parity anomaly and the HLF\neffective action, respectively. Hence, we have constructed the dimensional\nladder for the torsional anomalies from the single-body Hamiltonian picture."
    },
    {
        "anchor": "Klein tunneling in carbon nanostructures: a free particle dynamics in\n  disguise: The absence of backscattering in metallic nanotubes as well as perfect Klein\ntunneling in potential barriers in graphene are the prominent electronic\ncharacteristics of carbon nanostructures. We show that the phenomena can be\nexplained by a peculiar supersymmetry generated by a first order Hamiltonian\nand zero order supercharge operators. Like the supersymmetry associated with\nsecond order reflectionless finite-gap systems, it relates here the low-energy\nbehavior of the charge carriers with the free particle dynamics.",
        "positive": "Theory of Interaction Effects in N-S Junctions out of Equilibrium: We consider a normal metal - superconductor (N-S) junction in the regime,\nwhen electrons in the normal metal are driven out of equilibrium. We show that\nthe non-equilibrium fluctuations of the electron density in the N-layer cause\nthe fluctuations of the phase of the order parameter in the S-layer. As a\nresult, the density of states in the superconductor deviates from the BCS form,\nmost notably the density of states in the gap becomes finite. This effect can\nbe viewed as a result of the time reversal symmetry breaking due to the\nnon-equilibrium, and can be described in terms of a low energy collective mode\nof the junction, which couples normal currents in N-layer and supercurrents.\nThis mode is analogous to the Schmid-Sch\\\"{o}n mode. To interpret their\nmeasurements of the tunneling current, Pothier {\\em et. al} [Phys. Rev. Lett.\n{\\bf 79}, 3490 (1997)] had to assume that the energy relaxation rate in the\nnormal metal is surprisingly high. The broadening of the BCS singularity of the\ndensity of states in the S-layer manifest itself similarly to the broadening of\nthe distribution function. Mechanism suggested here can be a possible\nexplanation of this experimental puzzle. We also propose an independent\nexperiment to test our explanation."
    },
    {
        "anchor": "Relation Between Local Temperature Gradients and the Direction of Heat\n  Flow in Quantum Driven Systems: We introduce thermometers to define the local temperature of an electronic\nsystem driven out-of-equilibrium by local ac fields. We discuss the behavior of\nthe local temperature along the sample, showing that it exhibits spatial\nfluctuations following an oscillatory pattern. We show explicitly that the\nlocal temperature is the correct indicator for heat flow.",
        "positive": "Comment on \"Theoretical analysis of the transmission phase shift of a\n  quantum dot in the presence of Kondo correlations\": Recently, A. Jerez, P. Vitushinsky and M. Lavagna [Phys. Rev. Lett. 95,\n127203 (2005)] claimed that the transmission phase through a quantum fot, as\nmeasured via the Aharonov-Bohm interferometer, differs from the phase which\ndetermines the corresponding conductance. Here we show that this claim is wrong\nfor the single level Anderson model, which is usually used to describe the\nquantum dot. So far, there exists no derivation of this claim from any explicit\ntheoretical model."
    },
    {
        "anchor": "Electrical Control of Coherent Spin Rotation of a Single-Spin Qubit: Nitrogen vacancy (NV) centers, optically-active atomic defects in diamond,\nhave attracted tremendous interest for quantum sensing, network, and computing\napplications due to their excellent quantum coherence and remarkable\nversatility in a real, ambient environment. One of the critical challenges to\ndevelop NV-based quantum operation platforms results from the difficulty to\nlocally address the quantum spin states of individual NV spins in a scalable,\nenergy-efficient manner. Here, we report electrical control of the coherent\nspin rotation rate of a single-spin qubit in NV-magnet based hybrid quantum\nsystems. By utilizing electrically generated spin currents, we are able to\nachieve efficient tuning of magnetic damping and the amplitude of the dipole\nfields generated by a micrometer-sized resonant magnet, enabling electrical\ncontrol of the Rabi oscillation frequency of NV spins. Our results highlight\nthe potential of NV centers in designing functional hybrid solid-state systems\nfor next-generation quantum-information technologies. The demonstrated coupling\nbetween the NV centers and the propagating spin waves harbored by a magnetic\ninsulator further points to the possibility to establish macroscale\nentanglement between distant spin qubits.",
        "positive": "Floquet-engineering topological transitions in a twisted transition\n  metal dichalcogenide homobilayer: Motivated by the recent experimental realization of twisted transition metal\ndichalcogenide bilayers, we study a simplified model driven by different forms\nof monochromatic light. As a concrete and representative example we use\nparameters that correspond to a twisted MoTe$_2$ homobilayer. First, we\nconsider irradiation with circularly polarized light in free space and\ndemonstrate that the corresponding Floquet Hamiltonian takes the same form as\nthe static Hamiltonian, only with a constant overall shift in quasi-energy.\nThis is in stark contrast to twisted bilayer graphene, where new terms are\ntypically generated under an analagous drive. Longitudinal light, on the other\nhand, which can be generated from the transverse magnetic mode in a waveguide,\nhas a much more dramatic effect--it renormalizes the tunneling strength between\nthe layers, which effectively permits the tuning of the twist angle {\\em\nin-situ}. We find that, by varying the frequency and amplitude of the drive,\none can induce a topological transition that cannot be obtained with the\ntraditional form of the Floquet drive in free space. Furthermore, we find that\nstrong drives can have a profound effect on the layer pseudospin texture of the\ntwisted system, which coincides with multiple simultaneous band gap closings in\nthe infinite-frequency limit. Surprisingly, these bandgap closings are not\nassociated with topological transitions. For high but finite drive frequencies\nnear $0.7$eV, the infinite-frequency band crossings become band gap minima of\nthe order of $10^{-6}$ eV or smaller."
    },
    {
        "anchor": "Transport properties of a two impurity system: a theoretical approach: A system of two interacting cobalt atoms, at varying distances, was studied\nin a recent scanning tunneling microscope experiment by Bork et. al.[Nature\nPhys. 7, 901 (2011)]. We propose a microscopic model that explains, for all\nexperimentally analyzed interatomic distances, the physics observed in these\nexperiments. Our proposal is based on the two-impurity Anderson model, with the\ninclusion of a two-path geometry for charge transport. This many-body system is\ntreated in the finite-U slave boson mean-field approximation and the\nlogarithmic-discretization embedded-cluster approximation. We physically\ncharacterize the different charge transport regimes of this system at various\ninteratomic distances and show that, as in the experiments, the features\nobserved in the transport properties depend on the presence of two impurities\nbut also on the existence of two conducting channels for electron transport. We\ninterpret the splitting observed in the conductance as the result of the\nhybridization of the two Kondo resonances associated with each impurity.",
        "positive": "Nonadiabatic Van der Pol oscillations in molecular transport: The force exerted by the electrons on the nuclei of a current-carrying\nmolecular junction can be manipulated to engineer nanoscale mechanical systems.\nIn the adiabatic regime a peculiarity of these forces is negative friction,\nresponsible for Van der Pol oscillations of the nuclear coordinates. In this\nwork we study the robustness of the Van der Pol oscillations against\nhigh-frequency bias and gate voltage. For this purpose we go beyond the\nadiabatic approximation and perform full Ehrenfest dynamics simulations. The\nnumerical scheme implements a mixed quantum-classical algorithm for open\nsystems and is capable to deal with arbitrary time-dependent driving fields. We\nfind that the Van der Pol oscillations are extremely stable. The nonadiabatic\nelectron dynamics distorts the trajectory in the momentum-coordinate phase\nspace but preserves the limit cycles in an average sense. We further show that\nhigh-frequency fields change both the oscillation amplitudes and the average\nnuclear positions. By switching the fields off at different times one obtains\ncycles of different amplitudes which attain the limit cycle only after\nconsiderably long times."
    },
    {
        "anchor": "An extensive comparison of anisotropies in MBE grown (Ga,Mn)As material: This paper reports on a detailed magnetotransport investigation of the\nmagnetic anisotropies of (Ga,Mn)As layers produced by various sources\nworldwide. Using anisotropy fingerprints to identify contributions of the\nvarious higher order anisotropy terms, we show that the presence of both a\n[100] and a [110] uniaxial anisotropy in addition to the primary ([100] +\n[010]) anisotropy is common to all medium doped (Ga,Mn)As layers typically used\nin transport measurement, with the amplitude of these uniaxial terms being\ncharacteristic of the individual layers.",
        "positive": "Nanomechanical Resonators and Their Applications in Biological/Chemical\n  Detection: Nanomechanics Principles: Recent advances in nanotechnology have led to the development of\nnano-electro-mechanical systems (NEMS) such as nanomechanical resonators, which\nhave recently received significant attention from the scientific community.\nThis has not only been for their capability for the label-free detection of\nbio/chemical-molecules at single-molecule (or atomic) resolution for future\napplications such as the early diagnostics of diseases such as cancer, but also\nfor their unprecedented ability to detect physical quantities such as molecular\nweight, elastic stiffness, surface stress, and surface elastic stiffness for\nadsorbed molecules on the surface. Most experimental works on resonator-based\nmolecular detection have been based on the principle that molecular adsorption\nonto a resonator surface increases the effective mass, and consequently\ndecreases the resonant frequencies of the nanomechanical resonator. However,\nthis principle is insufficient to provide fundamental insights into\nresonator-based molecular detection at the nanoscale; this is due to recently\nproposed novel nanoscale detection principles including various effects such as\nsurface effects, nonlinear oscillations, coupled resonance, and stiffness\neffects. Therefore, our objective in this review is to overview the current\nattempts to understand the underlying mechanisms in nanoresonator-based\ndetection using physical models coupled to computational simulations and/or\nexperiments. Specifically, we will focus on issues of special relevance to the\ndynamic behavior of nanoresonators and their applications in\nbiological/chemical detection. We additionally provide extensive discussion\nregarding potentially fruitful future research directions coupling experiments\nand simulations in order to develop a fundamental understanding of the basic\nphysical principles that govern NEMS and NEMS-based sensing applications."
    },
    {
        "anchor": "A gauge-invariant and current-continuous microscopic ac quantum\n  transport theory: There had been consensus on what the accurate ac quantum transport theory was\nuntil some recent works challenged the conventional wisdom. Basing on the\nnon-equilibrium Green's function formalism for time-dependent quantum\ntransport, we derive an expression for the dynamic admittance that satisfies\ngauge invariance and current continuity, and clarify the key concept in the\nfield. The validity of our now formalism is verified by first-principles\ncalculation of the transient current through a carbon-nanotube-based device\nunder the time-dependent bias voltage. Moreover, the previously well-accepted\nexpression for dynamic admittance is recovered only when the device is a\nperfect conductor at a specific potential.",
        "positive": "Bright $\\mathrm{\\textit{ab-initio}}$ photoluminescence of NV+ in diamond: The positively charged nitrogen vacancy (NV+) centre in diamond has been\ntraditionally treated as a dark state due to the experimental lack of an\noptical signature. Recent computational studies have shown that it is possible\nfor the NV+ defect to have an excited state transition equivalent to that of\nthe negatively charged (NV-) centre, but no PL predictions have been reported\nso far. We report the first $\\mathrm{\\textit{ab-initio}}$ calculation showing\nthat the NV+ center presents quantum emission, with zero phonon line at 765 nm\nand a non-zero transition dipole moment, approximately 4x smaller than the\ntransition dipole moment of NV-. We calculate the energy levels of the\nmultielectron states under time-dependent density functional theory (singlet\nand triplet E states), and using our recently developed frequency cutoff\nmethod, we predict the full PL spectrum. Our results suggest that this state\ncannot be considered intrinsically 'dark' and charge specific quenching\nmechanisms should be investigated as the cause of the lack of optical activity\nin experimental characterizations."
    },
    {
        "anchor": "Analytical Model for Metamaterials with Quantum Ingredients: We present an analytical model for describing complex dynamics of a hybrid\nsystem consisting of interacting classical and quantum resonant structures.\nClassical structures in our model correspond to plasmonic nano-resonators of\ndifferent geometries, as well as other types of nano- and micro-structures\noptical response of which can be described without invoking quantum-mechanical\ntreatment. Quantum structures are represented by atoms or molecules, or their\naggregates (for example, quantum dots and carbon nanotubes), which can be\naccurately modelled only with the use of quantum approach. Our model is based\non the set of equations that combines well-established density matrix formalism\nappropriate for quantum systems, coupled with harmonic-oscillator equations\nideal for modelling sub-wavelength plasmonic and optical resonators. This model\ncan also be straightforwardly adopted for describing electromagnetic dynamics\nof various hybrid systems outside the photonics realm, such as\nJosephson-junction metamaterials, or SQUID elements coupled with an RF strip\nresonator.",
        "positive": "Spin transport enhancement by controlling the Ag growth in lateral spin\n  valves: The role of the growth conditions in the spin transport properties of silver\n(Ag) have been studied by using lateral spin valve structures. By changing the\ndeposition conditions of Ag from polycrystalline to epitaxial growth, we have\nobserved a considerable enhancement of the spin diffusion length, from\n$\\lambda_{Ag}$ = 449 $\\pm$ 30 to 823 $\\pm$ 59 nm. This study shows that\ndiminishing the grain boundary contribution to the spin relaxation mechanism is\nan effective way to improve the spin diffusion length in metallic\nnanostructures."
    },
    {
        "anchor": "Plasmon wakefields and dispersive properties of metallic nanostructures: We investigate the excitation of electrostatic wakefields in metallic\nnanostructures (nanowires) due to the propagation of a short electron pulse.\nFor that purpose, a dispersive (nonlocal) dielectric response of the system is\nconsidered, accounting for both the finiteness of the system and the quantum\n(Bohm) difraction of the conduction electron band, generalizing the results\nobtained previously in the literature [Phys. Rev. Lett. \\textbf{103}, 097403\n(2009)]. We discuss on the stability conditions of wakefields and show that the\nunderling mechanism can be useful to investigate new sources of radiation in\nthe extreme-ultra-violet (XUV) range.",
        "positive": "Transient transport spectroscopy of an interacting quantum dot\n  proximized by a superconductor: Charge- and heat-currents after a switch: We analyze the time-evolution of a quantum dot which is proximized by a\nlarge-gap superconductor and weakly probed using the charge and heat currents\ninto a wide-band metal electrode. We map out the full time dependence of these\ncurrents after initializing the system by a switch. We find that due to the\nproximity effect there are two simple yet distinct switching procedures which\ninitialize a non-stationary mixture of the gate-voltage dependent eigenstates\nof the proximized quantum dot. We find in particular that the ensuing\ntime-dependent heat current is a sensitive two-particle probe of the interplay\nof strong Coulomb interaction and induced superconducting pairing. The pairing\ncan lead to a suppression of charge and heat current decay which we analyze in\ndetail. The analysis of the results makes crucial use of analytic formulas\nobtained using fermionic duality, a ``dissipative symmetry'' of the master\nequation describing this class of open systems."
    },
    {
        "anchor": "Abrikosov vortex nucleation and its detrimental effect on\n  superconducting spin pumping in Pt/Nb/Ni80Fe20/Nb/Pt proximity structures: We report Abrikosov vortex nucleation in Pt/Nb/Ni80Fe20/Nb/Pt\nproximity-coupled structures under oblique ferromagnetic resonance (FMR) that\nturns out to be detrimental to superconducting spin pumping. By measuring an\nout-of-plane field-angle {\\theta}H dependence and comparison with Pt-absent\ncontrol samples, we show that as {\\theta}H increases, the degree of enhancement\n(suppression) of spin pumping efficiency in the superconducting state for the\nPt-present (Pt-absent) sample diminishes and it reverts to the normal state\nvalue at {\\theta}H = 90{\\deg}. This can be explained in terms of a substantial\nout-of-plane component of the resonance field for the Ni80Fe20 layer (with\nin-plane magnetization anisotropy and high aspect ratio) that approaches the\nupper critical field of the Nb, turning a large fraction of the singlet\nsuperconductor volume into the normal state.",
        "positive": "Adhesion mechanics of graphene on textured substrates: Graphene, the 2D form of carbon, has excellent mechanical, electrical and\nthermal properties and a variety of potential applications including NEMS,\nprotective coatings, transparent electrodes in display devices and biological\napplications. Adhesion plays a key role in many of these applications. In\naddition, it has been proposed that the electronic properties of graphene can\nbe affected by elastic deformation caused by adhesion of graphene to its\nsubstrate. In light of this, we present here a continuum mechanics based\ntheoretical framework to understand the effect of nanoscale morphology of\nsubstrates on adhesion and mechanics of graphene. In the first part, we analyze\nthe adhesion mechanics of graphene on 1 and 2D periodic corrugations. We\ncarried out molecular statics simulations and found the results to be in good\nagreement with our theory. We modeled adhesive interactions surface forces\ndescribed by Lennard-Jones 6-12 potential in both our analysis and simulations\nand in principle can be extended to any other interaction potential. The\nresults show that graphene adheres conformally to substrates with large\ncurvatures. We showed in principal that the theory developed here can be\nextended to substrates of arbitrary shapes that can be represented by a Fourier\nseries. In the second part, we study the mechanics of peeling of graphene\nribbons from 1D sinusoidally textured substrates. In the molecular statics\nsimulations, we observed two key features in the peel mechanics of the ribbons:\nthe ribbons slide over the substrate and undergo adhesion and peeling near the\ncrack front in an oscillatory manner, the frequency of which reveals the\nwavelength of the underlying substrate. Our theory qualitatively captures these\nfeatures of the peel mechanics and is general enough that it can be extended to\nother 2D materials like MoS2, BN etc and different kinds of interaction\npotentials."
    },
    {
        "anchor": "Room Temperature Gate Tunable Non Reciprocal Charge Transport in Lattice\n  Matched InSb/CdTe Heterostructures: The manipulation of symmetry provides an effective way to tailor the physical\norders in solid-state systems. With the breaking of both the inversion and\ntime-reversal symmetries, non-reciprocal magneto-transport may emerge in\nassorted non-magnetic systems to enrich spintronic physics. Here, we report the\nobservation of the uni-directional magneto-resistance (UMR) in the\nlattice-matched InSb/CdTe film up to room temperature. Benefiting from the\nstrong built-in electric field of $0.13 \\mathrm{~V} \\cdot \\mathrm{nm}^{-1}$ in\nthe hetero-junction region, the resulting Rashba-type spin-orbit coupling and\nquantum confinement warrant stable angular-dependent second-order charge\ncurrent with the non-reciprocal coefficient 1-2 orders of magnitude larger than\nmost non-centrosymmetric materials at 298 K. More importantly, this\nheterostructure configuration enables highly-efficient gate tuning of the\nrectification response in which the enhancement of the UMR amplitude by 40% is\nrealized. Our results advocate the narrow-gap semiconductor-based hybrid system\nwith the robust two-dimensional interfacial spin texture as a suitable platform\nfor the pursuit of controllable chiral spin-orbit devices and applications.",
        "positive": "Decoherence-induced conductivity in the discrete 1D Anderson model: A\n  novel approach to even-order generalized Lyapunov exponents: A recently proposed statistical model for the effects of decoherence on\nelectron transport manifests a decoherence-driven transition from\nquantum-coherent localized to ohmic behavior when applied to the\none-dimensional Anderson model. Here we derive the resistivity in the ohmic\ncase and show that the transition to localized behavior occurs when the\ncoherence length surpasses a value which only depends on the second-order\ngeneralized Lyapunov exponent $\\xi^{-1}$. We determine the exact value of\n$\\xi^{-1}$ of an infinite system for arbitrary uncorrelated disorder and\nelectron energy. Likewise all higher even-order generalized Lyapunov exponents\ncan be calculated, as exemplified for fourth order. An approximation for the\nlocalization length (inverse standard Lyapunov exponent) is presented, by\nassuming a log-normal limiting distribution for the dimensionless conductance\n$T$. This approximation works well in the limit of weak disorder, with the\nexception of the band edges and the band center."
    },
    {
        "anchor": "Spin textures in strongly coupled electron spin and magnetic or nuclear\n  spin systems in quantum dots: Controlling electron spins strongly coupled to magnetic and nuclear spins in\nsolid state systems is an important challenege in the field of spintronics and\nquantum computation. We show here that electron droplets with no net spin in\nsemiconductor quantum dots strongly coupled with magnetic ion/nuclear spin\nsystems break down at low temperature and form a non-trivial anti-ferromagnetic\nspatially ordered spin-texture of magneto-polarons. The spatially ordered\ncombined electron-magnetic ion spin-texture, associated with spontaneous\nsymmetry-breaking in the parity of electronic charge density and magnetization\nof magnetic ions, emerge from both ab-initio density functional approach to the\nelectronic system coupled with mean-field approximation for the\nmagnetic/nuclear spin system and fully mircoscopic exact diagonalization of\nsmall systems. The predicted phase diagram determines the critical temperature\nas a function of coupling strength and identifies possible phases of the\nstrongly coupled spin system. This prediction may arrest fluctuations in spin\nsystem and open the way to control, manipulate and prepare magnetic and nuclear\nspin ensembles in semiconductor nanostructures.",
        "positive": "Application of a semiclassical model for the second-quantized\n  many-electron Hamiltonian to nonequilibrium quantum transport: The resonant\n  level model: A semiclassical (SC) approach is developed for nonequilibrium quantum\ntransport in molecular junctions. Following the early work of Miller and White\n[J. Chem. Phys. 84, 5059 (1986)], the many-electron Hamiltonian in second\nquantization is mapped onto a classical model that preserves the fermionic\ncharacter of electrons. The resulting classical electronic Hamiltonian allows\nfor real-time molecular dynamics simulations of the many-body problem from an\nuncorrelated initial state to the steady state. Comparisons with exact results\ngenerated for the resonant level model reveal that a semiclassical treatment of\ntransport provides a quantitative description of the dynamics at all relevant\ntimescales for a wide range of bias and gate potentials, and for different\ntemperatures. The approach opens a door to treating nontrivial quantum\ntransport problems that remain far from the reach of fully quantum\nmethodologies."
    },
    {
        "anchor": "Surface enhanced circular dichroism spectroscopy mediated by non-chiral\n  nanoantennas: We theoretically investigate light matter interactions for chiral molecules\nin the presence of non-chiral nanoantennas. Isotropic nanostructures supporting\noptical-frequency electric or magnetic dipoles are sufficient to locally\nenhance the excitation of a molecule's chiral polarizability and thus its\ncircular dichroism spectrum. However, simultaneous electric and magnetic\ndipoles are necessary to achieve a net, spatially-averaged enhancement. Our\ncontribution provides a theoretical framework to understand chiral light-matter\ninteractions at the nanoscale and sets the necessary and sufficient conditions\nto enhance circular dichroism spectroscopy in the presence of nanoantennas. The\nresults may lead to new, field-enhanced, chiral spectroscopic techniques.",
        "positive": "Quantum master equation descriptions of a nanomechanical resonator\n  coupled to a single-electron transistor: We analyse the quantum dynamics of a nanomechanical resonator coupled to a\nnormal-state single-electron transistor (SET). Starting from a microscopic\ndescription of the system, we derive a master equation for the SET island\ncharge and resonator which is valid in the limit of weak electro-mechanical\ncoupling. Using this master equation we show that, apart from brief transients,\nthe resonator always behaves like a damped harmonic oscillator with a shifted\nfrequency and relaxes into a thermal-like steady state. Although the behaviour\nremains qualitatively the same, we find that the magnitude of the resonator\ndamping rate and frequency shift depend very sensitively on the relative\nmagnitudes of the resonator period and the electron tunnelling time. Maximum\ndamping occurs when the electrical and mechanical time-scales are the same, but\nthe frequency shift is greatest when the resonator moves much more slowly than\nthe island charge. We then derive reduced master equations which describe just\nthe resonator dynamics. By making slightly different approximations, we obtain\ntwo different reduced master equations for the resonator. Apart from minor\ndifferences, the two reduced master equations give rise to a consistent picture\nof the resonator dynamics which matches that obtained from the master equation\nincluding the SET island charge."
    },
    {
        "anchor": "Spiraling Fermi arcs in Weyl materials: In Weyl materials the valence and conduction electron bands touch at an even\nnumber of isolated points in the Brillouin zone. In the vicinity of these\npoints the electron dispersion is linear and may be described by the massless\nDirac equation. This results in nontrivial topology of Berry connection\ncurvature. One of its consequences is the existence of peculiar surface\nelectron states whose Fermi surfaces form arcs connecting projections of the\nWeyl points onto the surface plane. Band bending near the boundary of the\ncrystal also produces surface states. We show that in Weyl materials band\nbending near the crystal surface gives rise to spiral structure of energy\nsurfaces of arc states. The corresponding Fermi surface has the shape of a\nspiral that winds about the projection of the Weyl point onto the surface\nplane. The direction of the winding is determined by the helicity of the Weyl\npoint and the sign of the band bending potential. For close valleys arc state\nmorphology may be understood in terms of avoided crossing of oppositely winding\nspirals.",
        "positive": "Two-Qubit Gates for Resonant Exchange Qubits: A new approach to single-qubit operations using exchange interactions of\nsingle electrons in gate-defined quantum dots has recently been demonstrated:\nthe resonant exchange qubit. We show that two-qubit operations, specifically\nthe CPHASE gate, can be performed between resonant exchange qubits very\nstraightforwardly, using a single exchange pulse. This is in marked contrast to\nthe best known protocols for exchange qubits where such a gate requires many\npulses so that leakage processes arising from the exchange interaction can be\novercome. For resonant exchange qubits a simple two-qubit gate is possible\nbecause in this mode of operation energy conservation suppresses leakage."
    },
    {
        "anchor": "Robust spin transfer torque in antiferromagnetic tunnel junctions: We theoretically study the current-induced spin torque in antiferromagnetic\ntunnel junctions, composed of two semi-infinite antiferromagnetic layers\nseparated by a tunnel barrier, in both clean and disordered regimes. We find\nthat the torque enabling the electrical manipulation of the N\\'eel\nantiferromagnetic order parameter is out of plane $\\sim {\\bf n}\\times{\\bf p}$,\nwhile the torque competing with the antiferromagnetic exchange is in-plane\n$\\sim {\\bf n}\\times({\\bf p}\\times{\\bf n})$. Here, ${\\bf { p}}$ and ${\\bf { n}}$\nare the N\\'eel order parameter direction of the reference and free layers,\nrespectively. Their bias dependence shows similar behavior as in ferromagnetic\ntunnel junctions, the in-plane torque being mostly linear in bias while the\nout-of-plane torque is quadratic. Most importantly, we find that the spin\ntransfer torque in antiferromagnetic tunnel junctions is much more robust\nagainst disorder than in antiferromagnetic metallic spin-valves due to the\ntunneling nature of spin transport.",
        "positive": "Electrical control of the valley Hall effect in bilayer MoS2 transistors: The valley degree of freedom of electrons in solids has been proposed as a\nnew type of information carriers beyond the electronic charge and spin. Recent\nexperimental demonstrations of the optical orientation of the valley\npolarization and generation of the valley current through the valley Hall\neffect in monolayer MoS2 have shown the potential of two-dimensional\nsemiconductor transition metal dichalcogenides for valley based electronic and\noptoelectronic applications. The valley Hall conductivity in monolayer MoS2, a\nnon-centrosymmetric crystal, however, cannot be easily tuned, presenting a\nchallenge for valley-based applications. Here we report the control of the\nvalley Hall effect in bilayer MoS2 transistors through a gate. The inversion\nsymmetry present in bilayer MoS2 was broken by the gate applied electric field\nperpendicular to the plane. The valley polarization near the edges of the\ndevice channels induced by the longitudinal electrical current was imaged by\nuse of Kerr rotation microscopy. The polarization is out-of-plane, has opposite\nsign for the two edges, and is strongly dependent on the gate voltage. The\nobservation is consistent with the symmetry dependent Berry curvature and\nvalley Hall conductivity in bilayer MoS2. Our results are another step towards\ninformation processing based on the valley degree of freedom."
    },
    {
        "anchor": "Probing the dynamics and coherence of a semiconductor hole spin via\n  acoustic phonon-assisted excitation: Spins in semiconductor quantum dots are promising local quantum memories to\ngenerate polarization-encoded photonic cluster states, as proposed in the\npioneering Rudolph-Lindner scheme [1]. However, harnessing the polarization\ndegree of freedom of the optical transitions is hindered by resonant excitation\nschemes that are widely used to obtain high photon indistinguishability. Here\nwe show that acoustic phonon-assisted excitation, a scheme that preserves high\nindistinguishability, also allows to fully exploit the polarization selective\noptical transitions to initialise and measure single spin states. We access the\ncoherence of hole spin systems in a low transverse magnetic field and directly\nmonitor the spin Larmor precession both during the radiative emission process\nof an excited state or in the quantum dot ground state. We report a spin state\ndetection fidelity of $94.7 \\pm 0.2 \\%$ granted by the optical selection rules\nand a $20\\pm5$~ns hole spin coherence time, demonstrating the potential of this\nscheme and system to generate linear cluster states with a dozen of photons",
        "positive": "Contact angle dependence on the fluid-wall dispersive energy: Vapor-liquid menisci of the truncated and shifted Lennard-Jones fluid between\nparallel planar walls are investigated by molecular dynamics simulation.\nThereby, the characteristic energy of the unlike dispersive interaction between\nfluid molecules and wall atoms is systematically varied to determine its\ninfluence on the contact angle. The temperature is varied as well, covering\nmost of the range between the triple point temperature and the critical\ntemperature of the bulk fluid. The transition between obtuse and acute angles\nis found to occur at a temperature-independent magnitude of the fluid-wall\ndispersive interaction energy. On the basis of the present simulation results,\nfluid-wall interaction potentials can be adjusted to contact angle\nmeasurements."
    },
    {
        "anchor": "Electrically-Insulating Flexible Films with Quasi-One-Dimensional\n  van-der-Waals Fillers as Efficient Electromagnetic Shields: We report polymer composite films containing fillers comprised of\nquasi-one-dimensional (1D) van der Waals materials, specifically transition\nmetal trichalcogenides containing 1D structural motifs that enable their\nexfoliation into bundles of atomic threads. These nanostructures are\ncharacterized by extremely large aspect ratios of up to 10^6. The polymer\ncomposites with low loadings of quasi-1D TaSe3 fillers (below 3 vol. %)\nrevealed excellent electromagnetic interference shielding in the X-band GHz and\nEHF sub-THz frequency ranges, while remaining DC electrically insulating. The\nunique electromagnetic shielding characteristics of these films are attributed\nto effective coupling of the electromagnetic waves to the high-aspect-ratio\nelectrically-conductive TaSe3 atomic-thread bundles even when the filler\nconcentration is below the electrical percolation threshold. These novel films\nare promising for high-frequency communication technologies, which require\nelectromagnetic shielding films that are flexible, lightweight, corrosion\nresistant, electrically insulating and inexpensive.",
        "positive": "Non-hermiticity in spintronics: oscillation death in coupled spintronic\n  nano-oscillators through emerging exceptional points: The emergence of exceptional points (EPs) in the parameter space of a\nnon-hermitian (2D) eigenvalue problem is studied in a general sense in\nmathematical physics, and has in the last decade successively reached the scope\nof experiments. In coupled systems, it gives rise to unique physical phenomena,\nwhich enable novel approaches for the development of seminal types of highly\nsensitive sensors. Here, we demonstrate at room temperature the emergence of\nEPs in coupled spintronic nanoscale oscillators and hence exploit the system's\nnon-hermiticity. We describe the observation of amplitude death of\nself-oscillations and other complex dynamics, and develop a linearized\nnon-hermitian model of the coupled spintronic system, which properly describes\nthe main experimental features. Interestingly, these spintronic nanoscale\noscillators are deployment-ready in different applicational technologies, such\nas field, current or rotation sensors, radiofrequeny and wireless devices and,\nmore recently, novel neuromorphic hardware solutions. Their unique and\nversatile properties, notably their large nonlinear behavior, open up\nunprecedented perspectives in experiments as well as in theory on the physics\nof exceptional points. Furthermore, the exploitation of EPs in spintronics\ndevises a new paradigm for ultrasensitive nanoscale sensors and the\nimplementation of complex dynamics in the framework of non-conventional\ncomputing."
    },
    {
        "anchor": "Spin effects in single-electron transport through carbon nanotube\n  quantum dots: We investigate the total spin in an individual single-wall carbon nanotube\nquantum dot with various numbers of electrons in a shell by using the ratio of\nthe saturation currents of the first steps of Coulomb staircases for positive\nand negative biases. The current ratio reflects the total-spin transition that\nis increased or decreased when the dot is connected to strongly asymmetric\ntunnel barriers. Our results indicate that total spin states with and without\nmagnetic fields can be traced by this method.",
        "positive": "Non-equilibrium Green's function based single-band tight-binding model\n  for Fe-MgO-Fe magnetic tunnel junction devices: Motivated by observation of very high tunnel magnetoresistance (TMR) in\nFe-MgO-Fe magnetic tunnel junction devices, we propose a theoretical model for\nthese devices based on a single-band tight-binding approximation. An effort is\nmade to capture the band dispersions over the two dimensional transverse\nBrillouin zone. In the transport direction, spin dependent Hamiltonian is\nprescribed for Delta_1 and Delta_5 bands. Non-equilibrium Green's function\nformalism is then used to calculate transport. Features like voltage dependence\nof TMR are captured quantitatively within this simple model and the trends\nmatch well with the ones predicted by ab-initio methods and experiments."
    },
    {
        "anchor": "Weyl fermions in cylindrical wires: The key feature of Weyl semimetals (WSM) is the presence of topologically\nprotected Dirac cones in a 3D material. We consider the effect of restricting\ngeometry on the spectrum of excitations in WSM using as a model a cylindrical\nWSM wire. For the full manifold of hard boundary conditions, we derive the\ngeneral form of the dispersion equation relating the energy of the excitations\nand their momentum along the wire. We show that only the special class of\nboundary conditions, corresponding to decoupled helicities or, equivalently, to\npinned directions of the electron spin on the surface, support massless\nexcitations. For a general boundary condition, these excitations acquire mass\ninversely proportional to the radius of the wire. This demonstrates that\nboundary phenomena may play a crucial role in formation of excitations in WSM\nbased structures.",
        "positive": "The Intrinsic Magnetization of Antiferromagnetic Textures: Antiferromagnets (AFMs) exhibit intrinsic magnetization when the order\nparameter spatially varies. This intrinsic spin is present even at equilibrium\nand can be interpreted as a twisting of the homogeneous AFM into a state with a\nfinite spin. Because magnetic moments couple directly to external magnetic\nfields, the intrinsic magnetization can alter the dynamics of antiferromagnetic\ntextures under such influence. Starting from the discrete Heisenberg model, we\nderive the continuum limit of the free energy of AFMs in the exchange\napproximation and explicitly rederive that the spatial variation of the\nantiferromagnetic order parameter is associated with an intrinsic magnetization\ndensity. We calculate the magnetization profile of a domain wall and discuss\nhow the intrinsic magnetization reacts to external forces. We show\nconclusively, both analytically and numerically, that a spatially inhomogeneous\nmagnetic field can move and control the position of domain walls in AFMs. By\ncomparing our model to a commonly used alternative parametrization procedure\nfor the continuum fields, we show that the physical interpretations of these\nfields depend critically on the choice of parametrization procedure for the\ndiscrete-to-continuous transition. This can explain why a significant amount of\nrecent studies of the dynamics of AFMs, including effective models that\ndescribe the motion of antiferromagnetic domain walls, have neglected the\nintrinsic spin of the textured order parameter."
    },
    {
        "anchor": "Evolution of non-thermal phonon and electron populations in\n  photo-excited germanium on picosecond timescales: We investigate from first-principles theory and experiment the generation of\nphonons on picosecond timescales and the relaxation of carriers in multiple\nconduction band valleys of photo-excited Ge by inter-valley electron-phonon\nscattering. We provide a full description of the phonon and electron relaxation\ndynamics without adjustable parameters. Simulations of the time-evolution of\nphonon populations, based on first-principles band structure and\nelectron-phonon and phonon-phonon matrix elements, are compared with data from\ntime-resolved x-ray diffuse scattering experiments, performed at the LCLS x-ray\nfree-electron laser facility, which measures the diffuse scattering intensity\nfollowing photo-excitation by a 50 fs near-infrared optical pulse. Comparing\ncalculations and measurements show that the intensity of the non-thermal x-ray\ndiffuse scattering signal, that is observed to grow substantially near the\nL-point of the Brillouin zone over 3-5 ps, is due to phonons generated by\nscattering of carriers between the $\\Delta$ and L valleys. Non-thermal phonon\npopulations throughout the Brillouin zone are observed and simulated from first\nprinciples without adjustable parameters for times up to 10 ps. With inclusion\nof phonon decay through 3-phonon processes, the simulations also account for\nother non-thermal features observed in the x-ray diffuse scattering intensity,\nwhich are due to anharmonic phonon-phonon scattering of the phonons initially\ngenerated by electron-phonon scattering.",
        "positive": "Multiplication of Qubits in a Doubly Resonant Bichromatic Field: Multiplication of spin qubits arises at double resonance in a bichromatic\nfield when the frequency of the radio-frequency (rf) field is close to that of\nthe Rabi oscillation in the microwave field, provided its frequency equals the\nLarmor frequency of the initial qubit. We show that the operational multiphoton\ntransitions of dressed qubits can be selected by the choice of both the\nrotating frame and the rf phase. In order to enhance the precision of dressed\nqubit operations in the strong-field regime, the counter-rotating component of\nthe rf field is taken into account."
    },
    {
        "anchor": "Electron interferometry in quantum Hall regime: Aharonov-Bohm effect of\n  interacting electrons: An apparent h/fe Aharonov-Bohm flux period, where f is an integer, has been\nreported in coherent quantum Hall devices. Such sub-period is not expected for\nnon-interacting electrons and thus is thought to result from interelectron\nCoulomb interaction. Here we report experiments in a Fabry-Perot interferometer\ncomprised of two wide constrictions enclosing an electron island. By carefully\ntuning the constriction front gates, we find a regime where interference\noscillations with period h/2e persist throughout the transition between the\ninteger quantum Hall plateaus 2 and 3, including half-filling. In a large\nquantum Hall sample, a transition between integer plateaus occurs near\nhalf-filling, where the bulk of the sample becomes delocalized and thus\ndissipative bulk current flows between the counterpropagating edges\n(\"backscattering\"). In a quantum Hall constriction, where conductance is due to\nelectron tunneling, a transition between forward- and back-scattering is\nexpected near the half-filling. In our experiment, neither period nor amplitude\nof the oscillations show a discontinuity at half-filling, indicating that only\none interference path exists throughout the transition. We also present\nexperiments and an analysis of the front-gate dependence of the phase of the\noscillations. The results point to a single physical mechanism of the observed\nconductance oscillations: Aharonov-Bohm interference of interacting electrons\nin quantum Hall regime.",
        "positive": "Nuclear magnetic resonance and nuclear spin relaxation in AlAs quantum\n  well probed by ESR: The study of nuclear magnetic resonance and nuclear spin-lattice relaxation\nwas conducted in an asymmetrically doped to $n\\sim1.8\\times10^{11}$ cm$^{-2}$\n16 nm AlAs quantum well grown in the $[001]$-direction. Dynamic polarization of\nnuclear spins due to the hyperfine interaction resulted in the so-called\nOverhauser shift of the two-dimensional conduction electron spin resonance. The\nmaximum shifts achieved in the experiments are several orders of magnitude\nsmaller than in GaAs-based heterostructures indicating that hyperfine\ninteraction is weak. The nuclear spin-lattice relaxation time extracted from\nthe decay of Overhauser shift over time turned out to depend on the filling\nfactor of the two-dimensional electron system. This observation indicates that\nnuclear spin-lattice relaxation is mostly due to the interaction between\nelectron and nuclear spins. Overhauser shift diminishes resonantly when the\nRF-radiation of certain frequencies was applied to the sample. This effect\nserved as an indirect, yet powerful method for nuclear magnetic resonance\ndetection: NMR quadrupole splitting of $^{75}$As nuclei was clearly resolved.\nTheoretical calculations performed describe well these experimental findings."
    },
    {
        "anchor": "Current noise of a superconducting single electron transistor coupled to\n  a resonator: We analyze the current and zero-frequency current noise properties of a\nsuperconducting single electron resonator (SSET) coupled to a resonator,\nfocusing on the regime where the SSET is operated in the vicinity of the\nJosephson quasiparticle resonance. We consider a range of coupling strengths\nand resonator frequencies to reflect the fact that in practice the system can\nbe tuned to quite a high degree with the resonator formed either by a\nnanomechanical oscillator or a superconducting stripline fabricated in close\nproximity to the SSET. For very weak couplings the SSET acts on the resonator\nlike an effective thermal bath. In this regime the current characteristics of\nthe SSET are only weakly modified by the resonator. Using a mean field\napproach, we show that the current noise is nevertheless very sensitive to the\ncorrelations between the resonator and the SSET charge. For stronger couplings,\nthe SSET can drive the resonator into limit cycle states where self-sustained\noscillation occurs and we find that regions of well-defined bistability exist.\nDynamical transitions into and out of the limit cycle state are marked by\nstrong fluctuations in the resonator energy, but these fluctuations are\nsuppressed within the limit cycle state. We find that the current noise of the\nSSET is strongly influenced by the fluctuations in the resonator energy and\nhence should provide a useful indicator of the resonator's dynamics.",
        "positive": "Observation of the quantum Hall effect in epitaxial graphene on\n  SiC(0001) with oxygen adsorption: In this letter we report on transport measurements of epitaxial graphene on\nSiC(0001) with oxygen adsorption. In a $50\\times 50 \\mu\\mathrm{m^2}$ size Hall\nbar we observe the half-integer quantum Hall effect with a transverse\nresistance plateau quantized at filling factor around $\\nu = 2$, an evidence of\nmonolayer graphene. We find low electron concentration of $9\\times 10^{11}\n\\textrm{cm}^{-2}$ and we show that a doping of $10^{13}\\textrm{cm}^{-2}$ which\nis characteristic of intrinsic epitaxial graphene can be restored by vacuum\nannealing. The effect of oxygen adsorption on carrier density is confirmed by\nlocal angle-resolved photoemission spectroscopy measurements. These results are\nimportant for understanding oxygen adsorption on epitaxial graphene and for its\napplication to metrology and mesoscopic physics where a low carrier\nconcentration is required."
    },
    {
        "anchor": "New memory devices based on the proton transfer process: Memory devices operating due to the fast proton transfer (PT) process are\nproposed by means of the first-principles calculations. Writing an information\nis performed using the electrostatic potential of the scanning tunneling\nmicroscopy (STM). Reading an information is based on the effect of the local\nmagnetization induced at the zigzag graphene nanoribbon (Z-GNR) edge -\nsaturated with oxygen or the hydroxy group - and can be realized with the use\nof the giant magnetoresistance (GMR), magnetic tunnel junction (MTJ) or\nspin-transfer torque (STT) devices. The energetic barriers for the hop-forward\nand -backward processes can be tuned by the distance and potential of the STM\ntip. Thus, enabling to tailor the non-volatile logic states. The proposed\nsystem enables very dense packing of the logic cells and could be used in the\nrandom access and flash memory devices.",
        "positive": "An atomistic-based F\u00f6ppl-von K\u00e1rm\u00e1n model for graphene: We deduce a non-linear continuum model of graphene for the case of finite\nout-of-plane displacements and small in-plane deformations. On assuming that\nthe lattice interactions are governed by the Brenner's REBO potential of 2nd\ngeneration and that self-stress is present, we introduce discrete strain\nmeasures accounting for up-to-the-third neighbor interactions. The continuum\nlimit turns out to depend on an average (macroscopic) displacement field and a\nrelative shift displacement of the two Bravais lattices that give rise to the\nhexagonal periodicity. On minimizing the energy with respect to the shift\nvariable, we formally determine a continuum model of F\\\"oppl-von K\\'arm\\'a\ntype, whose constitutive coefficients are given in terms of the atomistic\ninteractions."
    },
    {
        "anchor": "Isotope sensitive measurement of the hole-nuclear spin interaction in\n  quantum dots: Decoherence caused by nuclear field fluctuations is a fundamental obstacle to\nthe realization of quantum information processing using single electron spins.\nAlternative proposals have been made to use spin qubits based on valence band\nholes having weaker hyperfine coupling. However, it was demonstrated recently\nboth theoretically and experimentally that the hole hyperfine interaction is\nnot negligible, although a consistent picture of the mechanism controlling the\nmagnitude of the hole-nuclear coupling is still lacking. Here we address this\nproblem by performing isotope selective measurement of the valence band\nhyperfine coupling in InGaAs/GaAs, InP/GaInP and GaAs/AlGaAs quantum dots.\nContrary to existing models we find that the hole hyperfine constant along the\ngrowth direction of the structure (normalized by the electron hyperfine\nconstant) has opposite signs for different isotopes and ranges from -15% to\n+15%. We attribute such changes in hole hyperfine constants to the competing\npositive contributions of p-symmetry atomic orbitals and the negative\ncontributions of d-orbitals. Furthermore, we find that the d-symmetry\ncontribution leads to a new mechanism for hole-nuclear spin flips which may\nplay an important role in hole spin decoherence. In addition the measured\nhyperfine constants enable a fundamentally new approach for verification of the\ncomputed Bloch wavefunctions in the vicinity of nuclei in semiconductor\nnanostructures.",
        "positive": "Quantum Boltzmann equation for bilayer graphene: A-B stacked bilayer graphene has massive electron and hole-like excitations\nwith zero gap in the nearest-neighbor hopping approximation. In equilibrium,\nthe quasiparticle occupation approximately follows the usual Fermi-Dirac\ndistribution. In this paper we consider perturbing this equilibrium\ndistribution so as to determine DC transport coefficients near charge\nneutrality. We consider the regime $\\beta |\\mu| \\lesssim 1$ (with $\\beta$ the\ninverse temperature and $\\mu$ the chemical potential) where there is not a well\nformed Fermi surface. Starting from the Kadanoff-Baym equations, we obtain the\nquantum Boltzmann equation of the electron and hole distribution functions when\nthe system is weakly perturbed out of equilibrium. The effect of phonons,\ndisorder, and boundary scattering for finite sized systems are incorporated\nthrough a generalized collision integral. The transport coefficients, including\nthe electrical and thermal conductivity, thermopower, and shear viscosity, are\ncalculated in the linear response regime. We also extend the formalism to\ninclude an external magnetic field. We present results from numerical solutions\nof the quantum Boltzmann equation. Finally, we derive a simplified two-fluid\nhydrodynamic model appropriate for this system, which reproduces the salient\nresults of the full numerical calculations."
    },
    {
        "anchor": "Gap formation in helical edge states with magnetic impurities: Helical edge states appear at the surface of two dimensional topological\ninsulators and are characterized by spin up traveling in one direction and the\nspin down traveling in the opposite direction. Such states are protected by\ntime reversal symmetry and no backscattering due to scalar impurities can\noccur. However, magnetic impurities break time reversal symmetry and lead to\nbackscattering. Often their presence is unintentional, but in some cases they\nare introduced into the sample to open up gaps in the spectrum. We investigate\nthe influence of random impurities on helical edge states, specifically how the\ngap behaves in the realistic case of impurities having both a magnetic and a\nscalar component. It turns out that for a fixed magnetic contribution the gap\ncloses when either the scalar component, or Fermi velocity is increased. We\ncompare diagrammatic techniques in the self-consistent Born approximation to\nnumerical calculations which yields good agreement. For experimentally relevant\nparameters we find that even moderate scalar components can be quite\ndetrimental for the gap formation.",
        "positive": "Topological states in multi-orbital HgTe honeycomb lattices: Research on graphene has revealed remarkable phenomena arising in the\nhoneycomb lattice. However, the quantum spin Hall effect predicted at the K\npoint could not be observed in graphene and other honeycomb structures of light\nelements due to an insufficiently strong spin-orbit coupling. Here we show\ntheoretically that 2D honeycomb lattices of HgTe can combine the effects of the\nhoneycomb geometry and strong spin-orbit coupling. The conduction bands,\nexperimentally accessible via doping, can be described by a tight-binding\nlattice model as in graphene, but including multi-orbital degrees of freedom\nand spin-orbit coupling. This results in very large topological gaps (up to 35\nmeV) and a flattened band detached from the others. Owing to this flat band and\nthe sizable Coulomb interaction, honeycomb structures of HgTe constitute a\npromising platform for the observation of a fractional Chern insulator or a\nfractional quantum spin Hall phase."
    },
    {
        "anchor": "Spin-valley resolved photon-assisted tunneling in carbon nanotube double\n  quantum dots: We consider the photon-assisted tunneling (PAT) and the\nLandau-Zener-Stueckelberg (LZS) interference for double quantum dots induced\nelectrostatically along a semiconducting carbon nanotube. An atomistic\ntight-binding approach and the time-dependent configuration interaction method\nare employed for description of the systems of a few confined electrons and\nholes. We reproduce the patterns of the LZS interference recently observed for\nthe quantum double dots describing transport across hole-localized states.\nMoreover, we indicate that for charge configurations for which the ground-state\nis Pauli blocked PAT can be used for resolution of the transitions that involve\nspin-flip or intervalley transitions without the spin-valley conserving\nbackground signal.",
        "positive": "Origins of Nonlocality near the Dirac Point in Graphene: We present an experimental study of nonlocal electrical signals near the\nDirac point in graphene. The in-plane magnetic field dependence of the nonlocal\nsignal confirms the role of spin in this effect, as expected from recent\npredictions of Zeeman spin Hall effect in graphene, but our experiments show\nthat thermo-magneto-electric effects also contribute to nonlocality, and the\neffect is sometimes stronger than that due to spin. Thermal effects are seen to\nbe very sensitive to sample details that do not influence other transport\nparameters."
    },
    {
        "anchor": "Strain effects on the thermal properties of ultra-scaled Si nanowires: The impact of uniaxial and hydrostatic stress on the ballistic thermal\nconductance ($\\kappa_{l}$) and the specific heat ($C_{v}$) of [100] and [110]\nSi nanowires are explored using a Modified Valence Force Field phonon model. An\nanisotropic behavior of $\\kappa_{l}$ and isotropic nature of $C_{v}$ under\nstrain are predicted for the two wire orientations. Compressive (tensile)\nstrain decreases (increases) $C_{v}$. The $C_{v}$ trend with strain is\ncontrolled by the high energy phonon sub-bands. Dominant contribution of the\nlow/mid (low/high) energy bands in [100] ([110]) wire and their variation under\nstrain governs the behavior of $\\kappa_{l}$.",
        "positive": "Anti-vortex state in cross-like nanomagnets: We report on results of computer micromodelling of anti-vortex states in\nasymmetrical cross-like ferromagnetic nanostructures and their practical\nrealization. The arrays of cobalt crosses with 1 mkm branches, 100 nm widths of\nthe branches and 40 nm thicknesses were fabricated using e-beam lithography and\nion etching. Each branch of the cross was tapered at one end and bulbous at the\nother. The stable formation of anti-vortex magnetic states in these\nnanostructures during magnetization reversal was demonstrated experimentally\nusing magnetic force microscopy."
    },
    {
        "anchor": "Quantum Phases in Partially Filled Landau Levels: We compare the energies of different electron solids, such as bubble crystals\nwith triangular and square symmetry and stripe phases, to those of correlated\nquantum liquids in partially filled intermediate Landau levels. Multiple\ntransitions between these phases when varying the filling of the top-most\npartially filled Landau level explain the observed reentrance of the integer\nquantum Hall effect. The phase transitions are identified as first-order. This\nleads to a variety of measurable phenomena such as the phase coexistence\nbetween a Wigner crystal and a two-electron bubble phase in a Landau-level\nfilling-factor range $4.15 < nu < 4.26$, which has recently been observed in\ntransport measurements under micro-wave irradiation.",
        "positive": "Disorder-induced phase transitions in double Weyl semimetals: The double Weyl semimetal (DWSM) is a newly proposed topological material\nthat hosts Weyl points with chiral charge n=2. The disorder effect in DWSM is\ninvestigated by adopting the tight-binding Hamiltonian. Using the transfer\nmatrix method and the noncommutative Kubo formula, we numerically calculate the\nlocalization length and the Hall conductivity in the presence of the on-site\nnonmagnetic disorder or orbital (spin-flip) disorders, and give the\ncorresponding global phase diagrams. For the on-site nonmagnetic disorder, the\nsystem undergoes the DWSM-3D quantum anomalous hall (3D QAH) and normal\ninsulator (NI)-DWSM phase transitions, and evolves into the diffusive metal\n(DM) phase before being localized by strong disorders, which is consistent with\nthe Weyl semimetal. For \\sigma_x orbital disorder, we find that increasing\ndisorder can generate a pair of Weyl nodes at the boundary of the Brillouin\nzone and induce a 3D QAH-DWSM phase transition. Then we investigate the\ncombined effect of orbital disorders for both disordered 3D QAH phase and DWSM\nphase. The disorder-induced transitions can be well understood in terms of an\neffective medium theory based on self-consistent Born approximation."
    },
    {
        "anchor": "Zero Bias Conductance Peak in Dirac Semimetal-Superconductor Devices: Majorana zero modes (MZMs), fundamental building blocks for realizing\ntopological quantum computers, can appear at the interface between a\nsuperconductor and a topological material. One of the experimental signatures\nthat has been widely pursued to confirm the existence of MZMs is the\nobservation of a large, quantized zero-bias conductance peak (ZBCP) in the\ndifferential conductance measurements. In this Letter, we report observation of\nsuch a large ZBCP in junction structures of normal metal (titanium/gold Ti/Au)\n+ Dirac semimetal (cadmium arsenide Cd3As2) + conventional superconductor\n(aluminum Al), with a value close to four times that of the normal state\nconductance. Our detailed analyses suggest that this large ZBCP is most likely\nnot caused by MZMs. We attribute the ZBCP, instead, to the existence of a\nsupercurrent between two far-separated superconducting Al electrodes, which\nshows up as a zero-bias peak because of the circuitry and thermal fluctuations\nof the supercurrent phase, a mechanism conceived by Ivanchenko and Zil'berman\nmore than 50 years ago [JETP 28, 1272 (1969)]. Our results thus call for\nextreme caution when assigning the origin of a large ZBCP to MZMs in a\nmultiterminal semiconductor or topological insulator/semimetal setup. We thus\nprovide criteria for identifying when the ZBCP is definitely not caused by an\nMZM. Furthermore, we present several remarkable experimental results of a\nsupercurrent effect occurring over unusually long distances and clean perfect\nAndreev reflection features.",
        "positive": "Light propagation and magnon-photon coupling in optically dispersive\n  magnetic media: Achieving strong coupling between light and matter excitations in hybrid\nsystems is a benchmark for the implementation of quantum technologies. We\nrecently proposed [arXiv:2110.02984] that strong single-particle coupling\nbetween magnons and light can be realized in a magnetized epsilon-near-zero\n(ENZ) medium, in which magneto-optical effects are enhanced. Here we present a\ndetailed derivation of the magnon-photon coupling Hamiltonian in dispersive\nmedia both for degenerate and non-degenerate optical modes, and show the\nenhancement of the coupling near the ENZ frequency. Moreover, we show that the\ncoupling of magnons to plane-wave non-degenerate Voigt modes vanishes at\nspecific frequencies due to polarization selection rules tuned by dispersion.\nFinally, we present specific results using a Lorentz dispersion model. Our\nresults pave the way for the design of dispersive optomagnonic systems,\nproviding a general theoretical framework for describing engineering ENZ-based\noptomagnonic systems."
    },
    {
        "anchor": "Formation of a \"Cluster Molecule\" (C20)2 and its thermal stability: The possible formation of a \"cluster molecule\" (C20)2 from two single C20\nfullerenes is studied by the tight-binding method. Several (C20)2 isomers in\nwhich C20 fullerenes are bound by strong covalent forces and retain their\nidentity are found; actually, these C20 fullerenes play the role of \"atoms\" in\nthe \"cluster molecule\". The so-called open-[2+2] isomer has a minimum energy.\nIts formation path and thermal stability at T = 2000 - 4000 K are analyzed in\ndetail. This isomer loses its molecular structure due to either the decay of\none of C20 fullerenes or the coalescence of two C20 fullerenes into a C40\ncluster. The energy barriers for the metastable open-[2+2] configuration are\ncalculated to be U = 2 - 5 eV.",
        "positive": "High tunability of the transport properties in macroscopically in-plane\n  modulated two-dimensional system: Gate-controllable two dimensional systems with in-plane modulation of\nproperties could serve as highly tunable effective media. Intuitively, such\nsystems may bring novel functionality provided that the period of the lateral\nmodulation is much less than the relevant scattering lengths (mean free path,\ncoherence length etc.). Our work experimentally demonstrates the opposite,\ndisordered limit of such system, defined in the macroscopically modulated\nmetal-oxide-semiconductor structure. The system consists of parent\ntwo-dimensional gas with periodic array of islands (dots/antidots), filled with\ntwo-dimensional gas of different density, and surrounded by depletion regions\n(shells). Carrier densities of both parent gas and islands are controlled by\ntwo independent gate electrodes, allowing us to explore a rich phase diagram of\nlow-temperature transport properties of this modulated two-dimensional system,\nresembling various transport regimes: insulating, shell-dominated,\ngas-dominated, island-dominated. These regimes can be identified by various\nHall resistance and its magnetic field dependence, temperature dependencies of\nthe resistivity, and Shubnikov-de Haas patterns. We also suggest the\ntheoretical approach for description of such inhomogeneous but periodical\nsystems. Theory based on the classical mean field approach qualitatively\ndescribes our system as theoretical dependencies reproduce the main features of\nthe experimental behavior of the effective Hall concentration from gate\nvoltage. Thus, our work demonstrates feasibility of the macroscopically\ninhomogeneous two-dimensional system as a tunable platform for novel physics\nand proposes the approach for the theoretical description of such systems."
    },
    {
        "anchor": "Heat transfer in the spin-boson model: A comparative study in the\n  incoherent tunneling regime: We study the transfer of heat in the non-equilibrium spin-boson model with an\nOhmic dissipation. In the non-adiabatic limit we derive a formula for the\nthermal conductance based on a rate equation formalism at the level of the\nnon-interacting blip approximation, valid for temperatures $T>T_K$, with $T_K$\nas the Kondo temperature. We evaluate this expression analytically assuming\neither weak or strong couplings, and demonstrate that our results agree with\nexact relations. Far-from-equilibrium situations are further examined, showing\na close correspondence to the linear response limit.",
        "positive": "Non-trivial Flat Bands in Three Dimensions: We report the presence of exactly and nearly flat bands with non-trivial\ntopology in a three-dimensional lattice model. We show that an approximate flat\nband with finite Chern number can be realized in a two-orbital square lattice\nby tuning the nearest-neighbor and next-nearest-neighbor hopping between the\ntwo orbitals. With this, we construct a minimal three-dimensional flat band\nmodel without stacking the two-dimensional layers. Specifically, we demonstrate\nthat a genuine three-dimensional non-trivial insulating phase can be realized\nby allowing only nearest and next-nearest hopping among different orbitals in\nthe third direction. We find both perfect and nearly perfect flat bands in all\nthree planes at some special parameter values. While the nearly flat band\ncarries a finite Chern number, the perfect flat bands have zero Chern number.\nFurther, we find that such a three-dimensional insulator with flat bands\ncarries an additional three-dimensional topological invariant, namely Hopf\ninvariant. Finally, we show that higher Chern models with Hopf invariant can\nalso be constructed with only nearest and next-nearest hopping, but the\nappearance of flat bands along high-symmetric points in the Brillouin zone\nrequires long-range hopping. We close with a discussion on possible\nexperimental platforms to realize the model."
    },
    {
        "anchor": "A fiber-integrated single photon source emitting at telecom wavelengths: Fiber-coupled single photon sources are essential components of\nphotonics-based quantum information processors. Most fiber-coupled single\nphoton sources require careful alignment between fibers and quantum emitters.\nIn this work, we present an alignment-free fiber-integrated single photon\nsource based on an InAs/InP quantum dot emitting at telecom wavelengths. We\ndesigned a nanobeam containing the quantum dots attached to a fiber taper. The\nadiabatic tapered coupler of the nanobeam enables efficient light coupling to\nthe fiber taper. Using a tungsten probe in a focused ion beam system, we\ntransferred the nanobeam to the fiber taper. The observed fiber-coupled single\nphoton emission occurs with a brightness of 1.5% and purity of 86%. This device\nprovides a building block for fiber-optic quantum circuits that have various\napplications, such as quantum communication and distributed quantum computing.",
        "positive": "Resonance Scattering of Waves in Chaotic Systems: This is a brief overview of RMT applications to quantum or wave chaotic\nresonance scattering, focusing mainly on theoretical results obtained via\nnon-perturbative methods starting from mid-nineties."
    },
    {
        "anchor": "Towards on-chip generation, routing and detection of non-classical light: We fabricate an integrated photonic circuit with emitter, waveguide and\ndetector on one chip, based on a hybrid superconductor-semiconductor system. We\ndetect photoluminescence from self-assembled InGaAs quantum dots on-chip using\nNbN superconducting nanowire single photon detectors. Using the fast temporal\nresponse of these detectors we perform time-resolved studies of non-resonantly\nexcited quantum dots. By introducing a temporal filtering to the signal, we are\nable to resonantly excite the quantum dot and detect its resonance uorescence\non-chip with the integrated superconducting single photon detector.",
        "positive": "Interacting Systems for Self-Correcting Low Power Switching: In this paper we first show that dynamic switching schemes can be used to\nreduce energy dissipation below the thermodynamic minimum of NkTlnr (N= number\nof state variables, 1/r=error probability), but only at the expense of the\nerror immunity inherent in thermodynamic processes for which the final state is\ninsensitive to the switching dynamics. It is further shown that, for a system\nwhich has internal feedback, e.g. nanomagnets, such that all N spins act in\nconcert, it should be possible to switch with an energy dissipation of the\norder of kTlnr (considerably less than the thermodynamic limit of NkTlnr),\nwhile retaining an error immunity comparable to thermodynamic switching."
    },
    {
        "anchor": "Observation of spin-wave moir\u00e9 edge and cavity modes in twisted\n  magnetic lattices: We report the experimental observation of the spin-wave moir\\'e edge and\ncavity modes using Brillouin light scattering spectro-microscopy in a\nnanostructured magnetic moir\\'e lattice consisting of two twisted triangle\nantidot lattices based on an yttrium iron garnet thin film. Spin-wave moir\\'e\nedge modes are detected at an optimal twist angle and with a selective\nexcitation frequency. At a given twist angle, the magnetic field acts as an\nadditional degree of freedom for tuning the chiral behavior of the magnon edge\nmodes. Micromagnetic simulations indicate that the edge modes emerge within the\noriginal magnonic band gap and at the intersection between a mini-flatband and\na propagation magnon branch. Our theoretical estimate for the Berry curvature\nof the magnon-magnon coupling suggests a non-trivial topology for the chiral\nedge modes and confirms the key role played by the dipolar interaction. Our\nfindings shed light on the topological nature of the magnon edge mode for\nemergent moir\\'e magnonics.",
        "positive": "Understanding plasmon dispersion in nearly-free-electron metals: the\n  relevance of exact constraints for novel exchange-correlation kernels within\n  time-dependent density functional theory: Small-wavevector excitations in Coulomb-interacting systems can be decomposed\ninto the high-energy collective longitudinal plasmon and the low-energy\nsingle-electron excitations. At the critical wavevector and corresponding\nfrequency where the plasmon branch merges with the single-electron excitation\nregion, the collective energy of the plasmon dissipates into single\nelectron-hole excitations. The jellium model provides a reasonable description\nof the electron-energy-loss spectrum (EELS) of metals close to the\nfree-electron limit. The random phase approximation (RPA) is exact in the\nhigh-density limit but can capture the plasmonic dispersion reasonably even for\ndensities with rs > 1. RPA and all beyond-RPA methods investigated here, result\nin a wrong infinite plasmon lifetime for a wavevector smaller than the critical\none where the plasmon dispersion curve runs into particle-hole excitations.\nExchange-correlation kernel corrections to RPA modify the plasmon dispersion\ncurve. There is however a large difference in the construction and form of the\nkernels investigated earlier. Our current work introduces recent model\nexchange-only and exchange-correlation kernels and discusses the relevance of\nsome exact constraints in the construction of the kernel. We show that, because\nthe plasmon dispersion samples a range of wavevectors smaller than the range\nsampled by the correlation energy, different kernels can make a strong\ndifference for the correlation energy and a weak difference for the plasmon\ndispersion. This work completes our understanding about the plasmon dispersion\nin realistic metals, such as Cs, where a negative plasmon dispersion has been\nobserved. We find only positive plasmon dispersion in jellium at the density\nfor Cs."
    },
    {
        "anchor": "Nonstationary theory of magnetic field induced current for molecular\n  spin nanojunction: For the study of molecular spin junctions, we take into account two types of\ncouplings between the molecule and the metal leads: (i) electron transfer that\ngives rise to net current in the biased junction and (ii) energy transfer\nbetween the molecule and the leads. Using a rotating wave approximation in the\nHeisenberg representation, we derive a set of differential equations for the\nexpectation values of relevant variables: electron and phonon populations and\nmolecular polarization. A magnetic field control method to enhance the charge\ntransfer at spin nanojunctions, which characterizes the molecule feature, is\ndiscussed. An approximate analytical solution of the resulting dynamical\nequation is supported by numerical solution. The magnetic control by charge\ntransfer is described by transient pseudo-fermions of electrons interacting\nwith spins. The rapid adiabatic passage of the energy between the molecule and\nthe leads is taken into account. The current for molecular spin nanojunctions\nis derived.",
        "positive": "Stable single-layer honeycomb like structure of silica: Silica or SiO$_2$, the main constituent of earth's rocks has several 3D\ncomplex crystalline and amorphous phases, but it does not have a graphite like\nlayered structure in 3D. Our theoretical analysis and numerical calculations\nfrom the first-principles predict a single-layer honeycomb like allotrope,\nh$\\alpha$-silica, which can be viewed to be derived from the oxidation of\nsilicene and it has intriguing atomic structure with re-entrant bond angles in\nhexagons. It is a wide band gap semiconductor, which attains remarkable\nelectromechanical properties showing geometrical changes under external\nelectric field. In particular, it is an auxetic metamaterial with negative\nPoisson's ratio and has a high piezoelectric coefficient. While it can form\nstable bilayer and multilayer structures, its nanoribbons can show metallic or\nsemiconducting behavior depending on their chirality. Coverage of dangling Si\norbitals by foreign adatoms can attribute new functionalities to\nh$\\alpha$-silica. In particular, Si$_2$O$_5$, where Si atoms are saturated by\noxygen atoms from top and bottom sides alternatingly can undergo a structural\ntransformation to make silicatene, another stable, single layer structure of\nsilica."
    },
    {
        "anchor": "Photoenhanced spin/valley polarization and tunneling magnetoresistance\n  in ferromagnetic-normal-ferromagnetic silicene junction: We theoretically demonstrate a simple way to significantly enhance the\nspin/valley polarizations and tunnel- ing magnetoresistnace (TMR) in a\nferromagnetic-normal-ferromagnetic (FNF) silicene junction by applying a\ncircularly polarized light in off-resonant regime to the second ferromagnetic\n(FM) region. We show that the fully spin-polarized current can be realized in\ncertain ranges of light intensity. Increasing the incident energy in the\npresence of light will induce a transition of perfect spin polarization from\npositive to negative or vice versa depending on magnetic configuration\n(parallel or anti-parallel) of FNF junction. Additionally, under a circularly\npolarized light, valley polarization is very sensitive to electric field and\nthe perfect valley polarization can be achieved even when staggered electric\nfield is much smaller than exchange field. The most important result we would\nlike to emphasize in this paper is that the perfect spin polarization and 100%\nTMR induced by a circularly polarized light are completely independent of\nbarrier height in normal region. Furthermore, the sign reversal of TMR can be\nobserved when the polarized direction of light is changed. A condition for\nobserving the 100% TMR is also reported. Our results are expected to be\ninformative for real applications of FNF silicene junction, especially in\nspintronics.",
        "positive": "Detection of phonon helicity in nonchiral crystals with Raman scattering: Recently, it has been predicted that the Berry curvature of electrons can\nproduce an angular momentum for phonons. In systems with time-reversal\nsymmetry, the direction of the phonon angular momentum is locked to the phonon\nwave vector. Accordingly, this phenomenon has received the name of ``phonon\nhelicity\". Here, we present a theory to unveil the signatures of such phonon\nhelicity using Raman scattering. We show that the intensity of Raman scattering\nfor circularly polarized light in BaMnSb$_2$ (a prototypical nonchiral Dirac\ninsulator) changes under a reversal of the phonon wave vector, and that the\nphonon helicity can be inferred from that change. We compare our results to\nrecent reports of Raman-based detection of phonon angular momentum in chiral\ncrystals."
    },
    {
        "anchor": "Multiple Cotunneling in Large Quantum Dot Arrays: We investigate the effects of inelastic cotunneling on the electronic\ntransport properties of gold nanoparticle multilayers and thick films at low\napplied bias, inside the Coulomb blockade regime. We find that the zero-bias\nconductance, $g_0(T)$, in all systems exhibits Efros-Shklovskii-type variable\nrange hopping transport. The resulting typical hopping distance, corresponding\nto the number of tunnel junctions participating in cotunneling events, is shown\nto be directly related to the power law exponent in the measured\ncurrent-voltage characteristics. We discuss the implications of these findings\nin light of models on cotunneling and hopping transport in mesoscopic, granular\nconductors.",
        "positive": "Transmission phase shifts of Kondo impurities: We study the coherent properties of transmission through Kondo impurities, by\nconsidering an open Aharonov-Bohm ring with an embedded quantum dot. We develop\na novel many-body scattering theory which enables us to calculate the\nconductance through the dot, the transmission phase shift, and the normalized\nvisibility, in terms of the single-particle T-matrix. For the single-channel\nKondo effect, we find at temperatures much below the Kondo temperature $T_K$\nthat the transmission phase shift is \\pi/2 without any corrections up to order\n(T/T_K)^2. The visibility has the form 1-(\\pi T/T_K)^2. For the non-Fermi\nliquid fixed point of the two channel Kondo, we find that transmission phase\nshift is \\pi/2 despite the fact that a scattering phase shift is not defined.\nAt zero temperature the visibility is 1/2, thus at zero temperature exactly\nhalf of the conductance is carried by single-particle processes. We explain\nthat the spin summation masks the inherent scattering phases of the dot, which\ncan be accessed only via a spin-resolved experiment. In addition, we calculate\nthe effect of magnetic field and channel anisotropy, and generalize to the\nk-channel Kondo case."
    },
    {
        "anchor": "Nondestructive method of thin film dielectric constant measurements by\n  two-wire capacitor: We suggest the nondestructive method for determination of the dielectric\nconstant of substrate-deposited thin films by capacitance measurement with two\nparallel wires placed on top of the film. The exact analytical formula for the\ncapacitance of such system is derived. The functional dependence of the\ncapacitance on dielectric constants of the film, substrate, and environment\nmedia and on the distance between the wires permits to measure the dielectric\nconstant of thin films for the vast set of parameters where previously proposed\napproximate methods are less efficient.",
        "positive": "Coherent time-dependent oscillations and temporal correlations in\n  triangular triple quantum dots: The fluctuation behavior of triple quantum dots (TQDs) has, so far, largely\nfocused on current cumulants in the long-time limit via full counting\nstatistics. Given that (TQDs) are non-trivial open quantum systems with many\ninteresting features, such as Aharonov-Bohm interference and coherent\npopulation blocking, new fluctuating-time statistics, such as the waiting time\ndistribution (WTD), may provide more information than just the current\ncumulants alone. In this paper, we use a Born-Markov master equation to\ncalculate the standard and higher-order WTDs for coherentlycoupled TQDs arrayed\nin triangular ring geometries for several transport regimes. In all cases we\nfind that the WTD displays coherent oscillations that correspond directly to\nindividual time-dependent dot occupation probabilities, a result also reported\nrecently in Ref.[1]. Our analysis, however, goes beyond the single-occupancy\nand single waiting time regimes, investigating waiting time behavior for TQDs\noccupied by multiple electrons and with finite electron-electron interactions.\nWe demonstrate that, in these regimes of higher occupancy, quantum coherent\neffects introduce correlations between successive waiting times, which we can\ntune via an applied magnetic field. We also show that correlations can be used\nto distinguish between TQD configurations that have identical FCS and that dark\nstates can be tuned with Aharonov-Bohm interference for more complicated\nregimes than single-occupancy."
    },
    {
        "anchor": "Strong interface-induced spin-orbit coupling in graphene on WS2: Interfacial interactions allow the electronic properties of graphene to be\nmodified, as recently demonstrated by the appearance of satellite Dirac cones\nin the band structure of graphene on hexagonal boron nitride (hBN) substrates.\nOngoing research strives to explore interfacial interactions in a broader class\nof materials in order to engineer targeted electronic properties. Here we show\nthat at an interface with a tungsten disulfide (WS2) substrate, the strength of\nthe spin-orbit interaction (SOI) in graphene is very strongly enhanced. The\ninduced SOI leads to a pronounced low-temperature weak anti-localization (WAL)\neffect, from which we determine the spin-relaxation time. We find that\nspin-relaxation time in graphene is two-to-three orders of magnitude smaller on\nWS2 than on SiO2 or hBN, and that it is comparable to the intervalley\nscattering time. To interpret our findings we have performed first-principle\nelectronic structure calculations, which both confirm that carriers in\ngraphene-on-WS2 experience a strong SOI and allow us to extract a\nspin-dependent low-energy effective Hamiltonian. Our analysis further shows\nthat the use of WS2 substrates opens a possible new route to access topological\nstates of matter in graphene-based systems.",
        "positive": "Half Metal Transition Driven by Doping Effects in Osmium Double\n  Perovskite: Using the first-principles density functional approach, we investigate\nCa$_2$FeOsO$_6$, a material of double perovskite structure synthesized\nrecently. According to the calculations, Ca$_2$FeOsO$_6$ is a ferrimagnetic\nMott-insulator influenced by the cooperative effect of spin-orbit coupling\n(SOC) and Coulomb interactions of Fe-3$d$ and Os-5$d$ electrons, as well as the\ncrystal field. When Fe is replaced with Ni, the system exhibits half metallic\n(HM) states desirable for spintronic applications. In\n[Ca$_2$Fe$_{1-x}$Ni$_x$OsO$_6$]$_2$, HM ferrimagnetism is observed with\n$\\mu_{\\rm tot}=2\\mu_{\\rm B}$ per unit cell for doping rate $x=0.5$, whereas HM\nantiferromagnetism (HMAFM) with nearly zero spin magnetization in the unit cell\nfor $x=1$, respectively. It is emphasized that half metallicity is retained\neven with SOC effect due to the large exchange-splitting between spin-up and\nspin-down bands close to the Fermi level."
    },
    {
        "anchor": "Strain-induced superfluid transition for atoms on graphene: Bosonic atoms deposited on atomically thin substrates represent a playground\nfor exotic quantum many-body physics due to the highly-tunable, atomic-scale\nnature of the interaction potentials. The ability to engineer strong\ninterparticle interactions can lead to the emergence of complex collective\natomic states of matter, not possible in the context of dilute atomic gases\nconfined in optical lattices. While it is known that the first layer of\nadsorbed helium on graphene is permanently locked into a solid phase, we show\nby a combination of quantum Monte Carlo and mean-field techniques, that simple\nisotropic graphene lattice expansion effectively unlocks a large variety of\ntwo-dimensional ordered commensurate, incommensurate, cluster atomic solid, and\nsuperfluid states for adsorbed atoms. It is especially significant that an\natomically thin superfluid phase of matter emerges under experimentally\nfeasible strain values, with potentially supersolid phases in close proximity\non the phase diagram.",
        "positive": "Valley-selective exciton bistability in a suspended monolayer\n  semiconductor: We demonstrate robust power- and wavelength-dependent optical bistability in\nfully suspended monolayers of WSe2 near the exciton resonance. Bistability has\nbeen achieved under continuous-wave optical excitation at an intensity level of\n10^3 W/cm^2. The observed bistability is originated from a photo-thermal\nmechanism, which provides both optical nonlinearity and passive feedback, two\nessential elements for optical bistability. Under a finite magnetic field, the\nexciton bistability becomes helicity dependent, which enables repeatable\nswitching of light purely by its polarization."
    },
    {
        "anchor": "Quasicrystalline electronic states in 30$^\\circ$ rotated twisted bilayer\n  graphene: The recently realized bilayer graphene system with a twist angle of\n$30^\\circ$ offers a new type of quasicrystal which unites the dodecagonal\nquasicrystalline nature and graphene's relativistic properties. Here, we\nintroduce a concise theoretical framework that fully respects both the\ndodecagonal rotational symmetry and the massless Dirac nature, to describe the\nelectronic states of the system. We find that the electronic spectrum consists\nof resonant states labeled by 12-fold quantized angular momentum, together with\nthe extended relativistic states. The resulting quasi-band structure is\ncomposed of the nearly flat bands with spiky peaks in the density of states,\nwhere the wave functions exhibit characteristic patterns which fit to the\nfractal inflations of the quasicrystal tiling. We also demonstrate that the\n12-fold resonant states appear as spatially-localized states in a finite-size\ngeometry, which is another hallmark of quasicrystal. The theoretical method\nintroduced here is applicable to a broad class of \"extrinsic quasicrystals\"\ncomposed of a pair of two-dimensional crystals overlaid on top of the other\nwith incommensurate configurations.",
        "positive": "Physical solutions of the Kitaev honeycomb model: We investigate the exact solution of the honeycomb model proposed by Kitaev\nand derive an explicit formula for the projector onto the physical subspace.\nThe physical states are simply characterized by the parity of the total\noccupation of the fermionic eigenmodes. We consider a general lattice on a\ntorus and show that the physical fermion parity depends in a nontrivial way on\nthe vortex configuration and the choice of boundary conditions. In the\nvortex-free case with a constant gauge field we are able to obtain an\nanalytical expression of the parity. For a general configuration of the gauge\nfield the parity can be easily evaluated numerically, which allows the exact\ndiagonalization of large spin models. We consider physically relevant\nquantities, as in particular the vortex energies, and show that their true\nvalue and associated states can be substantially different from the one\ncalculated in the unprojected space, even in the thermodynamic limit."
    },
    {
        "anchor": "Inhibited Recombination of Charged Magnetoexcitons: Time-resolved photoluminescence measurements show that the decay time for\ncharged excitons in a GaAs two-dimensional electron gas increases by an order\nof magnitude at high magnetic fields. Unlike neutral excitons, the charged\nexciton center-of-mass is spatially confined in a ``magnetically-adjustable\nquantum dot'' by the cyclotron orbit and the quantum well. The inhibited\nrecombination is explained by a reduced phase coherence volume of the\nmagnetically-confined charged excitons.",
        "positive": "Control of electron-hole pair generation by biharmonic voltage drive of\n  a quantum point contact: A time-dependent electromagnetic field creates electron-hole excitations in a\nFermi sea at low temperature. We show that the electron-hole pairs can be\ngenerated in a controlled way using harmonic and biharmonic time-dependent\nvoltages applied to a quantum contact and obtain the probabilities of the pair\ncreations. For a biharmonic voltage drive, we find that the probability of a\npair creation decreases in the presence of an in-phase second harmonic. This\naccounts for the suppression of the excess noise observed experimentally\n[Gabelli and Reulet, arXiv:1205.3638] proving that dynamic control and\ndetection of elementary excitations in quantum conductors are within the reach\nof the present technology."
    },
    {
        "anchor": "Thermoelectric Transport of Massive Dirac Fermions in Bilayer Graphene: Thermoelectric power (TEP) is measured in bilayer graphene for various\ntemperatures and charge-carrier densities. At low temperatures, measured TEP\nwell follows the semiclassical Mott formula with a hyperbolic dispersion\nrelation. TEP for a high carrier density shows a linear temperature dependence,\nwhich demonstrates a weak electron-phonon interaction in the bilayer graphene.\nFor a low carrier density, a deviation from the Mott relation is observed at\nhigh temperatures and is attributed to the low Fermi temperature in the bilayer\ngraphene. Oscillating TEP and the Nernst effect for varying carrier density,\nobserved in a high magnetic field, are qualitatively explained by the two\ndimensionality of the system.",
        "positive": "Anomalous quantum scattering and transport of electrons with Mexican-hat\n  dispersion induced by electrical potential: We theoretically study the quantum scattering and transport of electrons with\nMexican-hat dispersion through both step and rectangular potential barriers by\nusing the transfer matrix method. Owing to the torus-like iso-energy lines of\nthe Mexican-hat dispersion, we observe the presence of double reflections and\ndouble transmissions in both two different barrier scenarios, i.e., the normal\nreflection (NR), retro-reflection (RR), normal transmission (NT), and specular\ntransmission (ST).For the step potential with electrons incident from the large\nwavevector, the transmission is primarily governed by NT with nearly negligible\nST, while the reflection is dominant by RR (NR) within (outside) the critical\nangle. Additionally, for electrons incident from the small wavevector, the NT\ncan be reduced to zero by adjusting the barrier, resulting in a significant\nenhancement of ST and RR. For the rectangular barrier, the transmission and\nreflection spectra resemble those of the step barrier, but there are two kinds\nof resonant tunneling which can lead to perfect NT or ST. There exists a\nnegative differential conductance (NDC) effect in the conductance spectrum. The\nconductance and the peak-to-valley ratio of the NDC effect can be effectively\ncontrolled by adjusting the height and width of the barrier as well as the\nincident energy. Our results provide a deeper understanding of the electron\nstates governed by the Mexican-hat dispersion."
    },
    {
        "anchor": "Transport spectroscopy of low disorder silicon tunnel barriers with and\n  without Sb implants: We present transport measurements of silicon MOS split gate structures with\nand without Sb implants. We observe classical point contact (PC) behavior that\nis free of any pronounced unintentional resonances at liquid He temperatures.\nThe implanted device has resonances superposed on the point contact transport\nindicative of transport through the Sb donors. We fit the differential\nconductance to a rectangular tunnel barrier model with a linear barrier height\ndependence on source-drain voltage and non-linear dependence on gate bias.\nEffects such as Fowler-Nordheim (FN) tunneling and image charge barrier\nlowering (ICBL) are considered. Barrier heights and widths are estimated for\nthe entire range of relevant biases. The barrier heights at the locations of\nsome of the resonances for the implanted tunnel barrier are between 15-20 meV,\nwhich are consistent with transport through shallow partially hybridized Sb\ndonors. The dependence of width and barrier height on gate voltage is found to\nbe linear over a wide range of gate bias in the split gate geometry but\ndeviates considerably when the barrier becomes large and is not described\ncompletely by standard 1D models such as FN or ICBL effects.",
        "positive": "Transient dynamics in the Anderson-Holstein model with interfacial\n  screening: We study the combined effects of electron-phonon coupling and dot-lead\nrepulsion in the transport properties of the Anderson-Holstein model. We employ\na recently proposed nonperturbative method to calculate the transient response\nof the system. By varying the initial conditions for the time propagation the\ncurrent exhibits transient oscillations of different nature. We are able to\ndisentangle two dynamical processes, namely the local charge rearrangement due\nto the dot-lead contacting and the establishment of the nonequilbrium many-body\nstate due to the application of the external bias. These processes involve\neither Franck-Condon excitations or transitions between the resonant level and\nthe Fermi energy of the leads."
    },
    {
        "anchor": "Electronic spectrum of Kekule patterned graphene considering second\n  neighbor-interactions: The effects of second-neighbor interactions in Kekule patterned graphene\nelectronic properties are studied starting from a tight-binding Hamiltonian.\nThereafter, a low-energy effective Hamiltonian is obtained by projecting the\nhigh energy bands at the Gamma point into the subspace defined by the Kekule\nwave vector. The spectrum of the low energy Hamiltonian is in excellent\nagreement with the one obtained from a numerical diagonalization of the full\ntight-binding Hamiltonian. The main effect of the second-neighbour interaction\nis that a set of bands gains an effective mass and a shift in energy, thus\nlifting the degeneracy of the conduction bands at the Dirac point. This band\nstructure is akin to a spin-one Dirac cone, a result expected for honeycomb\nlattices with a distinction between one third of the atoms in one sublattice.\nFinally, we present a study of Kekule patterned graphene nanoribbons. This\nshows that the previous effects are enhanced as the width decreases. Moreover,\nedge states become dispersive, as expected due to second neighbors interaction,\nbut here the Kek-Y bond texture results in an hybridization of both edge\nstates. The present study shows the importance of second neighbors in realistic\nmodels of Kekule patterned graphene, specially at surfaces.",
        "positive": "Mapping the phase diagram of the quantum anomalous Hall and topological\n  Hall effects in a dual-gated magnetic topological insulator heterostructure: We use magnetotransport in dual-gated magnetic topological insulator\nheterostructures to map out a phase diagram of the topological Hall and quantum\nanomalous Hall effects as a function of the chemical potential (primarily\ndetermined by the back gate voltage) and the asymmetric potential (primarily\ndetermined by the top gate voltage). A theoretical model that includes both\nsurface states and valence band quantum well states allows the evaluation of\nthe variation of the Dzyaloshinskii-Moriya interaction and carrier density with\ngate voltages. The qualitative agreement between experiment and theory provides\nstrong evidence for the existence of a topological Hall effect in the system\nstudied, opening up a new route for understanding and manipulating chiral\nmagnetic spin textures in real space."
    },
    {
        "anchor": "Particle-hole pair states of layered materials: In the paper a theoretical study the both the quantized energies of excitonic\nstates and their wave functions in gapped graphene and in monolayer of MoS2 is\npresented. An integral two-dimensional Schr\\\"odinger equation of the\nelectron-hole pairing for a particles with electron-hole symmetry of reflection\nis analytically solved. The solutions of Schr\\\"odinger equation in momentum\nspace in gapped graphene and in the direct band monolayer of MoS2 by projection\nthe two-dimensional space of momentum on the three-dimensional sphere are\nfound. We analytically solve an integral two-dimensional Schr\\\"odinger equation\nof the electron-hole pairing for particles with electron-hole symmetry of\nreflection and with strong spin-orbit coupling. In monolayer of MoS2 as well as\nin single-layer graphene (SLG) the electron-hole pairing leads to the exciton\ninsulator states. Calculating an integral two-dimensional Schr\\\"odinger\nequation of the electron-hole pairing for bilayer graphene, an exciton\ninsulator states with a gap 3 meV are predicted. The particle-hole symmetry of\nDirac equation of layered materials allows perfect pairing between electron\nFermi sphere and hole Fermi sphere in the valence band and conduction band and\nhence driving the Cooper instability.",
        "positive": "Simulation and optimization of HEMTs: We have developed a simulation system for nanoscale high-electron mobility\ntransistors, in which the self-consistent solution of Poisson and Schr\\\"odinger\nequations is obtained with the finite element method. We solve the exact set of\nnonlinear differential equations to obtain electron wave function, electric\npotential distribution, electron density, Fermi surface energy and current\ndensity distribution in the whole body of the device. For more precision, local\ndependence of carrier mobility on the electric field distribution is\nconsidered. We furthermore compare the simulation to a recent experimental\nmeasurement and observe perfect agreement. We also propose a graded channel\ndesign to improve the transconductance and thereby the threshold frequency of\nthe device."
    },
    {
        "anchor": "Electromagnetic interaction between a metallic nanoparticle and surface\n  in tunnelling proximity modelling and experiment: We simulate the localized surface plasmon resonances of an Au nanoparticle\nwithin tunneling proximity of a Au substrate and demonstrate that the modes may\nbe identified with those responsible for light emission from a scanning\ntunneling microscope. Relative to the modes of an isolated nanoparticle these\nmodes show significant red-shifting, extending further into the infrared with\nincreasing radius, primarily due to a proximity-induced lowering of the\neffective bulk plasmon frequency. Spatial mapping of the field enhancement\nfactor shows an oscillatory variation of the field, absent in the case of a\ndielectric substrate; also the degree of localization of the modes, and thus\nthe resolution achievable electromagnetically, is shown to depend primarily on\nthe nanoparticle radius with only a weak dependence on wavelength.",
        "positive": "The Hierarchy of Excitation Lifetimes in Two-Dimensional Fermi Gases: Momentum-conserving quasiparticle collisions in two-dimensional Fermi gases\ngive rise to a large family of exceptionally long-lived excitation modes. The\nlifetimes of these modes exceed by a factor $(T_F/T)^2\\gg 1$ the conventional\nLandau Fermi-liquid lifetimes $\\tau\\sim T_F/T^2$. The long-lived modes have a\ndistinct angular structure, taking the form of $\\cos m\\theta$ and $\\sin\nm\\theta$ with odd $m$ values for a circular Fermi surface, with relaxation rate\ndependence on $m$ of the form $m^4\\log m$, valid at not-too-large $m$. In\ncontrast, the even-$m$ harmonics feature conventional lifetimes with a weak $m$\ndependence. The long-time dynamics, governed by the long-lived modes, takes the\nform of angular (super)diffusion over the Fermi surface. Altogether, this leads\nto unusual long-time memory effects, defining an intriguing transport regime\nthat lies between the conventional ballistic and hydrodynamic regimes."
    },
    {
        "anchor": "Relaxation Dynamics of Meso-Reservoirs: We study the phenomenology of maximum-entropy meso-reservoirs, where we\nassume that their local thermal equilibrium state changes consistently with the\nheat transferred between the meso-reservoirs. Depending on heat and matter\ncarrying capacities, the chemical potentials and temperatures are allowed to\nvary in time, and using global conservation relations we solve their evolution\nequations. We compare two-terminal transport between bosonic and fermionic\nmeso-reservoirs via systems that tightly couple energy and matter currents and\nsystems that do not. For bosonic reservoirs we observe the temporary formation\nof a Bose-Einstein condensate in one of the meso-reservoirs from an initial\nnonequilibrium setup.",
        "positive": "Discommensuration-enhanced superconductivity in the charge density wave\n  phases of transition-metal dichalcogenides: We introduce a McMillan-Ginzburg-Landau theory to describe the cooperative\ncoexistence of charge-density and superconducting order in two-dimensional\ncrystals. With a free-energy that explicitly accounts for the competition\nbetween commensurate and incommensurate ground states, we are able to map the\ntransition between these phases and monitor the development of\ndiscommensurations in the near-commensurate regime. Attributing the enhancement\nof superconducting order to density-wave fluctuations, we propose a coupling\nscheme that yields a phase diagram in qualitative agreement with experiments in\nconducting transition metal dichalcogenides. The model predicts the development\nof non-uniform superconductivity similar to that arising from a pair-density\nwave, with a spatial texture driven by the underlying charge-density wave\nfluctuations."
    },
    {
        "anchor": "Magnetic control of spin-orbit fields: a first-principles study of\n  Fe/GaAs junctions: The microscopic structure of spin-orbit fields for the technologically\nimportant Fe/GaAs interface is uncovered from first principles. A symmetry\nbased method allows to obtain the spin-orbit fields---both their magnitude and\norientation---for a generic Bloch state, from the electronic band structure for\nany in-plane magnetization orientation. It is demonstrated that the spin-orbit\nfields depend not only on the electric field across the interface, but also\nsurprisingly strongly on the Fe magnetization orientation, opening prospects\nfor their magnetic control. These results give important clues in searching for\nspin-orbit transport and optical phenomena in ferromagnetic/nonmagnetic\nsystems.",
        "positive": "Compressibility enhancement in an almost staggered interacting Harper\n  model: We discuss the compressibility in the almost staggered fermionic Harper model\nwith repulsive interactions in the vicinity of half-filling. It has been shown\nby Kraus et al. [33] that for spinless electrons and nearest neighbors\nelectron-electron interactions the compressibility in the central band is\nenhanced by repulsive interactions. Here we would like to investigate the\nsensitivity of this conclusion to the spin degree of freedom and longer range\ninteractions. We use the Hartree-Fock (HF) approximation, as well as density\nmatrix renormalization group (DMRG) calculation to evaluate the\ncompressibility. In the almost staggered Harper model, the central energy band\nis essentially flat and separated from the other bands by a large gap and\ntherefore, the HF approximation is rather accurate.In both cases the\ncompressibility of the system is enhanced compare to the non-interacting case,\nalthough the enhancement is weaker due to the inclusion of Hubbard and longer\nranged interactions."
    },
    {
        "anchor": "Linear dynamic polarizability and absorption spectrum of an exciton in a\n  quantum ring in a magnetic field: The problem of an electron-hole system interacting through a contact\npotential and moving in a one-dimensional quantum ring threaded by an\nAharonov-Bohm flux is considered, both with respect to the system's energetics\nas well as its optical properties. An exact analytical expression for the\nenergy spectrum is derived using a straightforward method based on boundary\nconditions for wavefunctions and their derivatives along the ring. The optical\nproperties of this exciton system, namely the linear dynamic polarizability and\nabsorption spectrum are investigated demonstrating certain unusual features. It\nis shown, for example, that for special values of the magnetic flux there are\nenergies in the spectrum that correspond to the dark excitonic states.",
        "positive": "Persistence of two-dimensional topological insulator state in wide HgTe\n  quantum well: Our experimental studies of electron transport in wide (14 nm) HgTe quantum\nwells confirm persistence of a two-dimensional topological insulator state\nreported previously for narrower wells, where it was justified theoretically.\nComparison of local and nonlocal resistance measurements indicate edge state\ntransport in the samples of about 1 mm size at temperatures below 1 K.\nTemperature dependence of the resistances suggests an insulating gap of the\norder of a few meV. In samples with sizes smaller than 10 $\\mu$m a\nquasiballistic transport via the edge states is observed."
    },
    {
        "anchor": "Excitonic condensation for the surface states of topological insulator\n  bilayers: We propose a generic topological insulator bilayer (TIB) system to study the\nexcitonic condensation with self-consistent mean-field (SCMF) theory. We show\nthat the TIB system presents the crossover behavior from the\nBardeen-Cooper-Schrieffer (BCS) limit to Bose-Einstein condensation (BEC)\nlimit. Moreover, by comparison with traditional semiconductor systems, we find\nthat for the present system the superfluid property in the BEC phase is more\nsensitive to electron-hole density imbalance and the BCS phase is more robust.\nApplying this TIB model into Bi$_{2}$Se$_{3}$-family material, we find that the\nBEC phase is most probable to be observed in experiment. We also calculate the\ncritical temperature for Bi$_{2}$Se$_{3}$-family TIB system, which is\n$\\mathtt{\\sim}100$ K. More interestingly, we can expect this relative\nhigh-temperature excitonic condensation since our calculated SCMF critical\ntemperature is approximately equal to the Kosterlitz-Thouless transition\ntemperature.",
        "positive": "Fractional Topological Superconductivity and Parafermion Corner States: We consider a system of weakly coupled Rashba nanowires in the strong\nspin-orbit interaction (SOI) regime. The nanowires are arranged into two\ntunnel-coupled layers proximitized by a top and bottom superconductor such that\nthe superconducting phase difference between them is $\\pi$. We show that in\nsuch a system strong electron-electron interactions can stabilize a helical\ntopological superconducting phase hosting Kramers partners of $\\mathbb{Z}_{2m}$\nparafermion edge modes, where $m$ is an odd integer determined by the position\nof the chemical potential. Furthermore, upon turning on a weak in-plane\nmagnetic field, the system is driven into a second-order topological\nsuperconducting phase hosting zero-energy $\\mathbb{Z}_{2m}$ parafermion bound\nstates localized at two opposite corners of a rectangular sample. As a special\ncase, zero-energy Majorana corner states emerge in the non-interacting limit\n$m=1$, where the chemical potential is tuned to the SOI energy of the single\nnanowires."
    },
    {
        "anchor": "Time-dependent transport via a quantum shuttle: We present a theoretical study of time-dependent transport via a quantum\nshuttle within the non-equilibrium Green's function technique. An arbitrary\nvoltage is applied to the tunnel junction and electrons in the leads are\nconsidered to be at zero temperature. The transient and the steady state\nbehavior of the system is considered here in order to explore the quantum\ndynamics of the shuttle device as a function of time and applied bias. The\nproperties of the phonon distribution of the oscillating dot coupled to the\nelectrons are investigated using a non-perturbative approach. We derive a\nrelation for the oscillator momentum charge density correlation function which\nis an interesting physical example for the visualization of shuttling\nphenomenon. We consider the crossover between the tunneling and shuttling\nregimes for different values of the key parameters as a function of applied\nbias and time. We also consider the energy transferred from the electrons to\nthe oscillating dot as a function of time. This will provide useful insight for\nthe design of experiments aimed at studying the quantum behavior of a shuttling\ndevice.",
        "positive": "Asymmetric Schottky Contacts in Bilayer MoS2 Field Effect Transistors: We discuss the high-bias electrical characteristics of back-gated\nfield-effect transistors with CVD-synthesized bilayer MoS2 channel and Ti\nSchottky contacts. We find that oxidized Ti contacts on MoS2 form rectifying\njunctions with ~0.3 to 0.5 eV Schottky barrier height. To explain the\nrectifying output characteristics of the transistors, we propose a model based\non two slightly asymmetric back-to-back Schottky barriers, where the highest\ncurrent arises from image force barrier lowering at the electrically forced\njunction, while the reverse current is due to Schottky-barrier limited\ninjection at the grounded junction. The device achieves a photo responsivity\ngreater than 2.5 AW-1 under 5 mWcm-2 white-LED light. By comparing two- and\nfour-probe measurements, we demonstrate that the hysteresis and persistent\nphotoconductivity exhibited by the transistor are peculiarities of the MoS2\nchannel rather than effects of the Ti/MoS2 interface."
    },
    {
        "anchor": "Spin-dependent transport through quantum-dot Aharonov-Bohm\n  interferometers: We study the influence of spin polarization on the degree of coherence of\nelectron transport through interacting quantum dots. To this end, we identify\ntransport regimes in which the degree of coherence can be related to the\nvisibility of the Aharonov-Bohm oscillations in the current through a\nquantum-dot Aharonov-Bohm interferometer with one normal and one ferromagnetic\nlead. For these regimes, we calculate the visibility and, thus, the degree of\ncoherence, as a function of the degree of spin polarization of the\nferromagnetic lead.",
        "positive": "Magnetic Field Pinning of a Dynamic Electron-Spin-Resonance Line in a\n  GaAs/AlGaAs Heterostructure: Electrically detected electron spin resonance (ESR) is used to study the\nhyperfine interaction of the two-dimensional electrons and the nuclei of the\nhost lattice in a GaAs/AlGaAs heterostructure. Under the microwave and radio-\nfrequency double excitations, we have observed that the ESR line can be pinned\nin a very narrow range of magnetic field - in the vicinity of the nuclear\nmagnetic resonance (NMR) of the nuclei of the GaAs crystal. Our observations\nsuggest that this pinning effect is the result of a competition process between\nthe ESR induced dynamic nuclear polarization and the NMR induced\ndepolarization."
    },
    {
        "anchor": "Electron transfer across a thermal gradient: Charge transfer is a fundamental process that underlies a multitude of\nphenomena in chemistry and biology. Recent advances in observing and\nmanipulating charge and heat transport at the nanoscale, and recently developed\ntechniques for monitoring temperature at high temporal and spatial resolution,\nimply the need for considering electron transfer across thermal gradients.\nHere, a theory is developed for the rate of electron transfer and the\nassociated heat transport between donor-acceptor pairs located at sites of\ndifferent temperatures. To this end, through application of a generalized\nmultidimensional transition state theory, the traditional Arrhenius picture of\nactivation energy as a single point on a free energy surface is replaced with a\nbithermal property that is derived from statistical weighting over all\nconfigurations where the reactant and product states are equienergetic. The\nflow of energy associated with the electron transfer process is also examined,\nleading to relations between the rate of heat exchange among the donor and\nacceptor sites as functions of the temperature difference and the electronic\ndriving bias. In particular, we find that an open electron transfer channel\ncontributes to enhanced heat transport between sites even when they are in\nelectronic equilibrium. The presented results provide a unified theory for\ncharge transport and the associated heat conduction between sites at different\ntemperatures.",
        "positive": "Spin-valley Silin modes in graphene with substrate-induced spin-orbit\n  coupling: In the presence of external magnetic field the Fermi-liquid state supports\noscillatory spin modes known as Silin modes. We predict the existence of the\ngeneralized Silin modes in a multivalley system, monolayer graphene. A gauge-\nand Berry-gauge- invariant kinetic equation for a multivalley Fermi liquid is\ndeveloped and applied to the case of graphene with extrinsic spin-orbit\ncoupling (SOC). The interplay of SOC and Berry curvature allows for the\nexcitation of generalized Silin modes in the spin and valley-staggered-spin\nchannels via an AC electric field. The resonant contributions from these modes\nto the optical conductivity are calculated."
    },
    {
        "anchor": "DMPK Equation for the Edge Transport of Quantum Spin Hall Insulator: Using the random matrix theory, we investigate the ensemble statistics of\nedge transport of a quantum spin Hall insulator with multiple edge states in\nthe presence of quenched disorder. Dorokhov-Mello-Pereyra-Kumar equation\napplicable for such a system is established. It is found that a two-dimensional\nquantum spin Hall insulator is effectively a new type of one-dimensional (1D)\nquantum conductor with the different ensemble statistics from that of the\nordinary 1D quantum conductor or the insulator with an even number of Kramers\nedge pairs. The ensemble statistics provides a physical manifestation of the\nZ2-classification for the time-reversal invariant insulators.",
        "positive": "Chiral Surface Modes in Three-Dimensional Topological Insulators: Where chiral modes should appear is an essential question for the quantum\nanomalous Hall (QAH) effect in three-dimensional topological insulators\n(3DTIs). In this Letter, we show that in a slab of ferromagnetic 3DTI subjected\nto a uniform exchange field normal to its top and bottom surfaces, the QAH\neffect creates a single chiral surface mode delocalized on the side faces. In a\nnonmagnetic 3DTI, analogously, delocalized helical modes consisting of a pair\nof oppositely propagating chiral surface modes are produced by the quantum spin\nHall effect."
    },
    {
        "anchor": "Conductance quantization in mesoscopic graphene: Using a generalized Landauer approach we study the non-linear transport in\nmesoscopic graphene with zig-zag and armchair edges. We find that for clean\nsystems, the low-bias low-temperature conductance, G, of an armchair edge\nsystem in quantized as G/t=4 n e^2/h, whereas for a zig-zag edge the\nquantization changes to G/t t=4(n+1/2)e^2/h, where t is the transmission\nprobability and n is an integer. We also study the effects of a non-zero bias,\ntemperature, and magnetic field on the conductance. The magnetic field\ndependence of the quantization plateaus in these systems is somewhat different\nfrom the one found in the two-dimensional electron gas due to a different\nLandau level quantization.",
        "positive": "Multiple Scattering Theory for Two-dimensional Electron Gases in the\n  Presence of Spin-Orbit Coupling: In order to model the phase-coherent scattering of electrons in\ntwo-dimensional electron gases in the presence of Rashba spin-orbit coupling, a\ngeneral partial-wave expansion is developed for scattering from a cylindrically\nsymmetric potential. The theory is applied to possible electron flow imaging\nexperiments using a moveable scanning probe microscope tip. In such\nexperiments, it is demonstrated theoretically that the Rashba spin-orbit\ncoupling can give rise to spin interference effects, even for unpolarized\nelectrons at nonzero temperature and no magnetic field."
    },
    {
        "anchor": "Quantum transport through pairs of edge states of opposite chirality at\n  electric and magnetic boundaries: We theoretically investigate electrical transport in a quantum Hall system\nhosting bulk and edge current carrying states. Spatially varying magnetic and\nelectric confinement creates pairs of current carrying lines that drift in the\nsame or opposite directions depending on whether confinement is applied by a\nmagnetic split gate or a magnetic strip gate. We study the electronic structure\nthrough calculations of the local density of states and conductivity of the\nchannel as a function of the chirality and wave-function overlap of these\nstates. We demonstrate a shift of the conductivity peaks to high or low\nmagnetic field depending on chirality of pairs of edge states and the effect of\nchirality on backscattering amplitude associated with collisional processes.",
        "positive": "Dissipation without resistance: Imaging impurities at quantum Hall edges: Motivated by the recent experiment by Marguerite et al. [1] on imaging in\ngraphene samples, we investigate theoretically the dissipation induced by\nresonant impurities in the quantum Hall regime. The impurity induced forward\nscattering of electrons at quantum Hall edges leads to an enhanced phonon\nemission, which reaches its maximum when the impurity state is tuned to\nresonance by a scanning tip voltage. Our analysis of the effect of the tip\npotential on the dissipation reveals peculiar thermal rings around the\nimpurities, in consistency with experimental observations. Remarkably, this\nimpurity-induced dissipation reveals non-trivial features that are unique for\nchiral 1D systems such as quantum Hall edges. First, the dissipation is not\naccompanied by the generation of resistance. Second, this type of dissipation\nis highly nonlocal: a single impurity induces heat transfer to phonons along\nthe whole edge."
    },
    {
        "anchor": "Room temperature quantum Hall effect in a gated ferroelectric-graphene\n  heterostructure: The quantum Hall effect is widely used for the investigation of fundamental\nphenomena, ranging from topological phases to composite fermions. In\nparticular, the discovery of a room temperature resistance quantum in graphene\nis significant for compact resistance standards that can operate above\ncryogenic temperatures. However, this requires large magnetic fields that are\naccessible only in a few high magnetic field facilities. Here, we report on the\nquantum Hall effect in graphene encapsulated by the ferroelectric insulator\nCuInP2S6. Electrostatic gating of the graphene channel enables the Fermi energy\nto be tuned so that electrons in the localized states of the insulator are in\nequilibrium with the current-carrying, delocalized states of graphene. Due to\nthe presence of strongly bound states in this hybrid system, a quantum Hall\nplateau can be achieved at room temperature in relatively modest magnetic\nfields. This phenomenon offers the prospect for the controlled manipulation of\nthe quantum Hall effect at room temperature.",
        "positive": "Ferromagnetic resonance in the complex permeability of an Fe$_3$O$_4$\n  nanosuspension at radio and microwave frequencies: The complex permeability of an iron-oxide nanosuspension has been measured as\na function of magnetic field strength at RF and microwave frequencies using a\nloop-gap resonator. The particles were suspended in water and had an 8-nm\ndiameter Fe$_3$O$_4$ core that was coated by Dextran. The real part of the\npermeability increased sharply beyond a frequency-dependent threshold value of\nthe static magnetic field before saturating. Just beyond this threshold field,\nthere was a peak in the imaginary part of the permeability. The permeability\nmeasurements, which exhibited features associated with ferromagnetic resonance,\nwere used to determine the dependence of the microwave absorption on static\nmagnetic field strength. Using the absorption data, the $g$-factor of the\nnanosuspension was found to be $1.86\\pm 0.07$."
    },
    {
        "anchor": "Voltage control of interface rare-earth magnetic moments: The large spin orbit interaction in rare earth atoms implies a strong\ncoupling between their charge and spin degrees of freedom. We formulate the\ncoupling between voltage and the local magnetic moments of rare earth atoms\nwith partially filled 4f shell at the interface between an insulator and a\nmetal. The rare earth-mediated torques allow power-efficient control of\nspintronic devices by electric field-induced ferromagnetic resonance and\nmagnetization switching.",
        "positive": "Excitonic theory of doping-dependent optical response in atomically thin\n  semiconductors: The interaction of optically excited excitons in atomically thin\nsemiconductors with residual doping densities leads to many-body effects which\nare continuously tunable by external gate voltages. Here, we develop a fully\nmicroscopic theory to describe the doping-dependent manipulation of the\nexcitonic properties in atomically thin transition metal dichalcogenides. In\nparticular, we establish a diagonalization approach for the Schr\\\"odinger\nequation which characterizes the interaction of a virtual exciton with the\nFermi sea of dopants. Solving this many-body Schr\\\"odinger equation provides\naccess to trions as well as a continuum of scattering states. The dynamics of\ncoupled excitons, trions, and scattering continua is subsequently described by\nHeisenberg equations of motion including mean-field contributions and\ncorrelation effects due to the interaction of excitons with trions and\nscattering continuum states. Our calculations for optical excitation close to\nthe band edge reveal the influence of doping on the exciton resonances in\ncombination with the simultaneous identification of not only ground-, but also\nexcited-, state trion resonances."
    },
    {
        "anchor": "Dynamic dielectric function and phonon self-energy from electrons\n  strongly correlated with acoustic phonons in 2D Dirac crystals: The unique structure of two-dimensional (2D) Dirac crystals, with electronic\nbands linear in the proximity of the Brillouin-zone boundary and the Fermi\nenergy, creates anomalous situations where small Fermi-energy perturbations are\nknown to critically affect the electron-related lattice properties of the\nsystem. The Fermi-surface nesting (FSN) conditions determining such effects via\nelectron-phonon interaction, require accurate estimates of the crystal's\nresponse function $(\\chi)$ as a function of the phonon wavevector q for any\nvalues of temperature. Numerous analytical estimates of $\\chi(q)$ for 2D Dirac\ncrystals beyond the Thomas-Fermi approximation have been so far carried out\nonly in terms of dielectric response function $\\chi(q,\\omega)$, for photon and\noptical-phonon perturbations, due to relative ease of incorporating a\nq-independent oscillation frequency in their calculation. However, models\naccounting for Dirac-electron interaction with ever-existing acoustic phonons,\nfor which $\\omega$ does depend on q and is therefore dispersive, are essential\nto understand many critical crystal properties. The lack of such models has\noften led to assume that the dielectric response function $\\chi(q)$ in these\nsystems can be understood from free-electron behavior. Here, we show that,\ndifferent from free-electron systems, $\\chi(q)$ calculated from acoustic\nphonons in 2D Dirac crystals using the Lindhard model, exhibits a cuspidal\npoint at the FSN condition. Strong variability of $\\frac{\\partial\\chi}{\\partial\nq}$ persists also at finite temperatures, while $\\chi(q)$ may tend to infinity\nin the dynamic case even where the speed of sound is small, albeit\nnonnegligible, over the Dirac-electron Fermi velocity. The implications of our\nfindings for electron-acoustic phonon interaction and transport properties such\nas the phonon line width derived from the phonon self energy will also be\ndiscussed.",
        "positive": "Band structure of a HgTe-based three-dimensional topological insulator: From the analysis of the cyclotron resonance, we experimentally obtain the\nband structure of the three-dimensional topological insulator based on a HgTe\nthin film. Top gating was used to shift the Fermi level in the film, allowing\nus to detect separate resonance modes corresponding to the surface states at\ntwo opposite film interfaces, the bulk conduction band, and the valence band.\nThe experimental band structure agrees reasonably well with the predictions of\nthe $\\mathbf{k\\cdot p}$ model. Due to the strong hybridization of the surface\nand bulk bands, the dispersion of the surface states is close to parabolic in\nthe broad range of the electron energies."
    },
    {
        "anchor": "Collective Spin Dynamics in the \"Coherence Window\" for Quantum\n  Nanomagnets: The spin coherence phenomena and the possibility of their observation in\nnanomagnetic insulators attract more and more attention in the last several\nyears. Recently it has been shown that in these systems in large transverse\nmagnetic field there can be a fairly narrow \"coherence window\" for phonon and\nnuclear spin-mediated decoherence. What kind of spin dynamics can then be\nexpected in this window in a crystal of magnetic nanomolecules coupled to\nphonons, to nuclear spin bath and it to each other via dipole-dipole\ninteractions? Studying multispin correlations, we determine the region of\nparameters where \"coherent clusters\" of collective spin excitations can appear.\nAlthough two particular systems, namely crystals of $Fe_8$-triazacyclonane and\n$Mn_{12}$-acetate molecules, are used in this work to illustrate the results,\nhere we are not trying to predict an existence of collective coherent dynamics\nin some particular system. Instead, we discuss the way how any crystalline\nsystem of dipole-dipole coupled nanomolecules can be analyzed to decide whether\nthis system is suitable for attempts to observe coherent dynamics. The\npresented analysis can be useful in the search for magnetic systems showing the\nspin coherence phenomena.",
        "positive": "Role of Strain on the Coherent Properties of GaAs Excitons and\n  Biexcitons: Polarization-dependent two-dimensional Fourier-transform spectroscopy (2DFTS)\nis performed on excitons in strained bulk GaAs layers probing the coherent\nresponse for differing amounts of strain. Biaxial tensile strain lifts the\ndegeneracy of heavy-hole (HH) and light-hole (LH) valence states, leading to an\nobserved splitting of the associated excitons at low temperature. Increasing\nthe strain increases the magnitude of the HH/LH exciton peak splitting, induces\nan asymmetry in the off-diagonal coherences, increases the difference in the HH\nand LH exciton homogenous linewidths, and increases the inhomogeneous\nbroadening of both exciton species. All results arise from strain-induced\nvariations in the local electronic environment, which is not uniform along the\ngrowth direction of the thin layers. For cross-linear polarized excitation,\nwherein excitonic signals give way to biexcitonic signals, the high-strain\nsample shows evidence of bound LH, HH, and mixed biexcitons."
    },
    {
        "anchor": "Spintronics on Chiral Objects: Chirality, handedness, is one of the most fundamental intriguing asymmetries\nin nature. By definition, chiral objects cannot be superimposed onto each other\nafter mirror reflection operation. Numerous examples of chiral structures can\nbe found in nature, for example, chiral molecules and chiral magnetic\nnanostructures. Moving electrons are associated with handedness by their own\nspins due to spin-orbit interaction thus exhibiting various emergent phenomena\nas they interact with chiral materials, which otherwise would not be observed\nin achiral systems. This new paradigm allows the potential development of new\nforms of devices or methods by utilizing reciprocal interaction of chiral\nobjects with moving electron spins. This review updates the remarkable\nprogresses in Spintronics on Chiral Objects that have been made over the past\nfew years providing provides an outlook for new opportunities and potential\napplications with new insights.",
        "positive": "Spin-selective electron transfer in quantum dot array: We propose a spin-selective coherent electron transfer in a\nsilicon-quantum-dot array. Oscillating magnetic fields and temporally\ncontrolled gate voltages are utilised to separate the electron wave function\ninto different quantum dots depending on the spin state. We introduce\nnon-adiabatic and adiabatic protocols which offer fast electron transfer and\nthe robustness against the error in the control-field pulse area, respectively.\nWe also study a shortcut-to-adiabaticity protocol which compromises these two\nprotocols. We show that this scheme can be extended to multi-electron systems\nstraightforwardly and used for non-local manipulations of the electrons."
    },
    {
        "anchor": "The limits of rechargeable spin battery: We discuss how the ideal rechargeable energy accumulator can be made, and\nwhat are the limits for solid state energy storage. We show that in theory the\nspin batteries based on heavy fermions can surpass the chemical ones by energy\ncapacitance. The absence of chemical reactions in spin batteries makes them\nmore stable, also they don't need to be heated in cold conditions. We study how\ncarriers statistics and density of states affect energy capacity of the\nbattery. Also, we discuss hypothetical spin batteries based on neutron stars.",
        "positive": "Dynamics Near a Photonic Band-Edge: Strong Coupling Effects Beyond\n  Rotating-Wave Approximation: We study the dynamics of a quantum emitter coupled to a two-dimensional\nphotonic crystal featuring a finite bandwidth with sharp edges and a Van-Hove\nsingularity. We study the effect of strong system-bath coupling and\nnon-Markovianity of the photonic environment using a nonperturbative approach\nbased on the recently introduced NCA dynamical map for open quantum systems. We\nshow that several characteristic features of the dynamics near a photonic\nband-edge such as the freezing of spontaneous emission and the maximum\nlight-matter entanglement, get strongly modified in presence of\ncounter-rotating terms in the system-bath coupling, beyond the rotating-wave\napproximation. Furthermore, by computing the spectral function of the quantum\nemitter we comment on the role played by atom-photon bound-state and show that\nthis acquires a much larger lifetime once the rotating-wave approximation is\nrelaxed."
    },
    {
        "anchor": "Aharonov-Bohm phase as quantum gate in two-electron charge qubits: We analyze the singlet-triplet splitting on a planar array of quantum dots\ncoupled capacitively to a set of external voltage gates. The system is modelled\nusing an extended Hubbard Hamiltonian keeping two excess electrons on the\narray. The voltage dependence of the low-energy singlet and triplet states is\nanalyzed using the Feshbach formalism. The formation of a well decoupled\ntwo-level system in the ground state is shown to rely on the fact of having two\nparticles in the system. Coherent operation of the array is studied with\nrespect to single quantum bit operations. One quantum gate is implemented via\nvoltage controls, while for the necessary second quantum gate, a uniform\nexternal magnetic field is introduced. The Aharonov-Bohm phases on the closed\nloop tunnel connections in the array are used to effectively suppress the\ntunneling, despite a constant tunneling amplitude in the structure. This allows\none to completely stall the qubit in any arbitrary quantum superposition,\nproviding full control of this interesting quantum system.",
        "positive": "Spin-orbit qubit in a semiconductor nanowire: Motion of electrons can influence their spins through a fundamental effect\ncalled spin-orbit interaction. This interaction provides a way to electrically\ncontrol spins and as such lies at the foundation of spintronics. Even at the\nlevel of single electrons, spin-orbit interaction has proven promising for\ncoherent spin rotations. Here we report a spin-orbit quantum bit implemented in\nan InAs nanowire, where spin-orbit interaction is so strong that spin and\nmotion can no longer be separated. In this regime we realize fast qubit\nrotations and universal single qubit control using only electric fields. We\nenhance coherence by dynamically decoupling the qubit from the environment. Our\nqubits are individually addressable: they are hosted in single-electron quantum\ndots, each of which has a different Land\\'e g-factor. The demonstration of a\nnanowire qubit opens ways to harness the advantages of nanowires for use in\nquantum computing. Nanowires can serve as one-dimensional templates for\nscalable qubit registers. Unique to nanowires is the possibility to easily vary\nthe material even during wire growth. Such flexibility can be used to design\nwires with suppressed decoherence and push semiconductor qubit fidelities\ntowards error-correction levels. Furthermore, electrical dots can be integrated\nwith optical dots in p-n junction nanowires. The coherence times achieved here\nare sufficient for the conversion of an electronic qubit into a photon, the\nflying qubit, for long-distance quantum communication."
    },
    {
        "anchor": "Unusual anisotropic magnetoresistance due to magnetization-dependent\n  spin-orbit interactions: One of recent surprising discoveries is the unusual anisotropic\nmagnetoresistance (UAMR) that depends on two magnetization components\nperpendicular to the current differently, in contrast to the conventional\nanisotropic magnetoresistance (AMR) that predicts no change in resistance when\nthe magnetization varies in the plane perpendicular to the current. Using\ndensity functional theory and Boltzmann transport equation calculations for bcc\nFe, hcp Co, and bcc FeCo alloys, we show that UAMR can be accounted by the\nmagnetization-dependent spin-orbit interactions (SOI): Magnetization-dependent\nSOI modifies electron energy bands that, in turn, changes resistance. A\nphenomenological model reveals the intrinsic connection between SOI and\norder-parameters. Such a mechanism is confirmed by the strong biaxial stain\neffect on UAMR. Our findings provide an efficient way of searching and\noptimizing materials with large UAMR, important in the design of\nhigh-performance spintronic devices.",
        "positive": "Spin drift-diffusion for two-subband quantum wells: Controlling the spin dynamics and spin lifetimes is one of the main\nchallenges in spintronics. To this end, the study of the spin diffusion in\ntwo-dimensional electron gases (2DEGs) shows that when the Rashba and\nDresselhaus spin-orbit couplings (SOC) are balanced, a persistent spin helix\nregime arises. There, a striped spin pattern shows a long lifetime, limited\nonly by the cubic Dresselhaus SOC, and its dynamics can be controlled by\nin-plane drift fields. Here, we derive a spin diffusion equation for\nnon-degenerate two-subbands 2DEGs. We show that the intersubband scattering\nrate, which is defined by the overlap of the subband densities, enters as a new\nnob to control the spin dynamics, and can be controlled by electric fields,\nbeing maximum for symmetric quantum wells. We find that for large intersubband\ncouplings the dynamics follow an effective diffusion matrix given by\napproximately half of the subband-averaged matrices. This extra 1/2 factor\narises from Matthiessen's rule summing over the intra- and intersubband\nscattering rates, and leads to a reduced diffusion constant and larger spin\nlifetimes. We illustrate our findings with numerical solutions of the diffusion\nequation with parameters extracted from realistic Schr\\\"odinger-Poisson\ncalculations."
    },
    {
        "anchor": "Trapping of electrons around nanoscale metallic wires embedded in a\n  semiconductor medium: We predict that conduction electrons in a semiconductor film containing a\ncentered square array of metal nanowires normal to its plane are bound in\nquantum states around the central wires, if a positive bias voltage is applied\nbetween the wires at the square vertices and these latter. We obtain and\ndiscuss the eigenenergies and eigenfunctions of two models with different\ndimensions. The results show that the eigenstates can be grouped into different\nshells. The energy differences between the shells is typically a few tens of\nmeV, which corresponds to frequencies of emitted or absorbed photons in a range\nof 3 THz to 20 THz approximately. These energy differences strongly depend on\nthe bias voltage. We calculate the linear response of individual electrons on\nthe ground level of our models to large-wavelength electromagnetic waves whose\nelectric field is in the plane of the semiconductor film. The computed\noscillator strengths are dominated by the transitions to the states in each\nshell whose wave function has a single radial node line normal to the wave\nelectric field. We include the effect of the image charge induced on the\ncentral metal wires and show that it modifies the oscillator strengths so that\ntheir sum deviates from the value given by the Thomas-Reiche-Kuhn rule. We\nreport the linear response, or polarizability, versus photon energy, of the\nstudied models and their absorption spectra. These latter show well-defined\npeaks as expected from the study of the oscillator strengths. We show that the\nposition of these absorption peaks is strongly dependent on the bias voltage so\nthat the frequency of photon absorption or emission in the systems described\nhere is easily tunable. This makes them good candidates for the development of\nnovel infrared devices.",
        "positive": "Disorder-Induced Quantum Phase Transitions in Three-Dimensional\n  Second-Order Topological Insulators: Disorder effects on three-dimensional second-order topological insulators\n(3DSOTIs) are investigated numerically and analytically. The study is based on\na tight-binding Hamiltonian for non-interacting electrons on a cubic lattice\nwith a reflection symmetry that supports a 3DSOTI in the absence of disorder.\nInterestingly, unlike the disorder effects on a topological trivial system that\ncan only be either a diffusive metal (DM) or an Anderson insulator (AI),\ndisorders can sequentially induce four phases of 3DSOTIs, three-dimensional\nfirst-order topologicalinsulators (3DFOTIs), DMs and AIs. At a weak disorder\nwhen the on-site random potential of strength $W$ is below a low critical value\n$W_{c1}$ at which the gap of surface states closes while the bulk sates are\nstill gapped, the system is a disordered 3DSOTI characterized by a constant\ndensity of states and a quantized integer conductance of $e^2/h$ through its\nchiral hinge states. The gap of the bulk states closes at a higher critical\ndisorder $W_{c2}$, and the system is a disordered 3DFOTI in a lower\nintermediate disorder between $W_{c1}$ and $W_{c2}$ in which electron\nconduction is through the topological surface states. The system becomes a DM\nin a higher intermediate disorder between $W_{c2}$ and $W_{c3}$ above which the\nstates at the Fermi level are localized. It undergoes a normal three-dimension\nmetal-to-insulator transition at $W_{c3}$ and becomes the conventional AI for\n$W>W_{c3}$. The self-consistent Born approximation allows one to see how the\ndensity of bulk states and the Dirac mass are modified by the on-site\ndisorders."
    },
    {
        "anchor": "The dielectric genome of van der Waals heterostructures: Vertical stacking of two-dimensional (2D) crystals, such as graphene and\nhexagonal boron nitride, has recently lead to a new class of materials known as\nvan der Waals heterostructures (vdWHs) with unique and highly tunable\nelectronic properties. Abinitio calculations should in principle provide a\npowerful tool for modeling and guiding the design of vdWHs, but in their\ntraditional, form such calculations are only feasible for commensurable\nstructures with a few layers. Here we show that the dielectric properties of\nrealistic, incommensurable vdWHs comprising hundreds of layers can be\ncalculated with ab-initio accuracy using a multi-scale approach where the\ndielectric functions of the individual layers (the dielectric building blocks)\nare coupled simply via their long-range Coulomb interaction. We use the method\nto illustrate the 2D- 3D dielectric transition in multi-layer MoS2 crystals,\nthe hybridization of quantum plasmons in large graphene/hBN heterostructures,\nand to demonstrate the intricate effect of substrate screening on the\nnon-Rydberg exciton series in supported WS2.",
        "positive": "Distinguishing thermal from non-thermal (\"hot\") carries in illuminated\n  molecular junctions: The search for the signature of non-thermal (so-called ``hot'') electrons in\nilluminated plasmonic nanostructures requires a detailed understanding of the\nnon-equilibrium electron distribution under illumination, as well as a careful\ndesign of the experimental system employed to distinguish non-thermal electrons\nfrom thermal ones. Here, we provide a theory for using plasmonic molecular\njunctions to achieve this goal. We show how non-thermal electrons can be\nmeasured directly and separately from the unavoidable thermal response, and\ndiscuss the relevance of our theory to recent experiments."
    },
    {
        "anchor": "Topological Hall signatures of magnetic hopfions: Magnetic hopfions are topologically protected three-dimensional solitons that\nare constituted by a tube which exhibits a topologically nontrivial spin\ntexture in the cross-section profile and is closed to a torus. Here we show\nthat the hopfion's locally uncompensated emergent field leads to a topological\nHall signature, although the topological Hall effect vanishes on the global\nlevel. The topological Hall signature is switchable by magnetic fields or\nelectric currents and occurs independently of the anomalous and conventional\nHall effects. It can therefore be exploited to electrically detect hopfions in\nexperiments and even to distinguish them from other textures like skyrmion\ntubes. Furthermore, it can potentially be utilized in spintronic devices.\nExemplarily, we propose a hopfion-based racetrack data storage device and\nsimulate the electrical detection of the hopfions as carriers of information.",
        "positive": "Pinning and movement of individual nanoscale magnetic skyrmions via\n  defects: An understanding of the pinning of magnetic skyrmions to defects is crucial\nfor the development of future spintronic applications. While pinning is\ndesirable for a precise positioning of magnetic skyrmions it is detrimental\nwhen they are to be moved through a material. We use scanning tunneling\nmicroscopy to study the interaction between atomic scale defects and magnetic\nskyrmions that are only a few nanometers in diameter. The studied pinning\ncenters range from single atom inlayer defects and adatoms to clusters adsorbed\non the surface of our model system. We find very different pinning strengths\nand identify preferred positions of the skyrmion. The interaction between a\ncluster and a skyrmion can be sufficiently strong for the skyrmion to follow\nwhen the cluster is moved across the surface by lateral manipulation with the\nSTM tip."
    },
    {
        "anchor": "Quantum thermoelectric and heat transport in the overscreened Kondo\n  regime: Exact conformal field theory results: We develop a conformal-field theory approach for investigation of the quantum\ncharge-, heat- and thermoelectric- transport through a quantum impurity fine\ntuned to a non-Fermi liquid regime. The non-Fermi-liquid operational mode is\nassociated with the overscreened spin Kondo effect and controlled by the number\nof orbital channels. The universal low-temperature scaling and critical\nexponents for Seebeck and Peltier coefficients are investigated for the\nmultichannel geometry. We derive and analyze the universal dependence of the\nthermoelectric coefficients on the number of orbital channels. We discuss the\nuniversality of Lorenz ratio and power factor beyond the Fermi Liquid paradigm.\nDifferent methods of verifying our findings based on the recent experiments are\nproposed.",
        "positive": "Dynamical creation of gap in the monolayer graphene: The zero gap electronic bands in the monolayer graphene are shown to be\nunstable relative to the dynamic symmetry violation due to the electron-phonon\ninteraction."
    },
    {
        "anchor": "Parallel Quantum Circuit in a Tunnel Junction: The spectrum of 1-state and 2-states per line quantum buses is used to\ndetermine the effective $V_{ab}(N)$ electronic coupling between emitter and\nreceiver states through the bus as a function of the number $N$ of parallel\nlines in the bus. When the calculation of $V_{ab}(N)$ is spectrally difficult,\nan Heisenberg-Rabi time dependent quantum exchange process can be triggered\nthrough the bus by preparing a specific initial non-stationanry state and\nidentifying a target state to capture the effective oscillation frequency\n$\\Omega_{ab}(N)$ between those. For $\\Omega_{ab}(N)$ (for $V_{ab}(N)$), two\ndifferent regimes are observed as a function of $N$: linear and $\\sqrt{N}$ more\nmoderate increases. This state preparation was remplaced by electronically\ncoupling the quantum bus to two semi-infinite electrodes. The native quantum\ntransduction process at work in this tunnel junction is not faithfully\nfollowing the $\\Omega_{ab}(N)$ variations with $N$. Due to normalisation to\nunity of the electronic transparency of the quantum bus and to the low pass\nfilter character of the transduction, large $\\Omega_{ab}(N)$ cannot be followed\nby the tunnel junction. At low coupling and when $N$ is small enough not to\ncompensate the small through line coupling, an $N^2$ power law is preserved for\n$\\Omega_{ab}(N)$. The limitations of the quantum transduction in a tunnel\njunction is pointing how the broadly used concept of electrical contact between\na metallic nanopad and a molecular wire can be better described as a quantum\ntransduction process.",
        "positive": "Strong photon coupling to the quadrupole moment of an electron in solid\n  state: The implementation of circuit quantum electrodynamics allows coupling distant\nqubits by microwave photons hosted in on-chip superconducting resonators.\nTypically, the qubit-photon interaction is realized by coupling the photons to\nthe electric dipole moment of the qubit. A recent proposal suggests storing the\nquantum information in the electric quadrupole moment of an electron in a\ntriple quantum dot. The qubit is expected to have improved coherence since it\nis insensitive to dipolar noise produced by distant voltage fluctuators. Here\nwe experimentally realize a quadrupole qubit in a linear array of three quantum\ndots in a GaAs/AlGaAs heterostructure. A high impedance microwave resonator\ncoupled to the middle dot interacts with the qubit quadrupole moment. We\ndemonstrate strong quadrupole qubit--photon coupling and observe improved\ncoherence properties when operating the qubit in the parameter space where the\ndipole coupling vanishes."
    },
    {
        "anchor": "Intermittent polaron dynamics: Born-Oppenheimer out of equilibrium: We consider the non-equilibrium dynamics of a molecular level interacting\nwith local phonon modes in the case of a strong polaronic shift which prevents\na perturbative treatment of the problem. Instead, we find that in an adiabatic\nregime when the electronic states react faster than the phonon modes it is\npossible to provide a fully non-perturbative treatment of the phonon dynamics\nincluding random noise and dissipation. The result shows intermittent switching\nbetween bistable states of the oscillator with an effective random telegraph\nnoise.",
        "positive": "Collective spin dynamics in magnetic nanomaterials: Magnetic nanomaterials are considered, formed by magnetic nanomolecules with\nhigh spins. The problem of spin reversal in these materials is analyzed, which\nis of interest for the possible use of such materials for quantum information\nprocessing and quantum computing. The fastest spin reversal can be achieved by\ncoupling the spin sample to a resonant electric circuit and by an appropriate\nchoice of the system parameters. A principal point is to choose these\nparameters so that to organize coherent spin motion. Dynamics of collective\nmotion is modelled by computer simulations, which confirm the high level of\ndynamical coherence of molecular spins in the process of spin reversal."
    },
    {
        "anchor": "Type-II Weyl cone transitions in driven semimetals: Periodically driven systems provide tunable platforms to realize interesting\nFloquet topological phases and phase transitions. In electronic systems with\nWeyl dispersions, the band crossings are topologically protected even in the\npresence of time-periodic perturbations. This robustness permits various routes\nto shift and tilt the Weyl spectra in the momentum and energy space using\ncircularly polarized light of sufficient intensity. We show that type-II Weyl\nfermions, in which the Weyl dispersions are tilted with the appearance of\npocket-like Fermi surfaces, can be induced in driven Dirac semimetals and line\nnode semimetals. Under a circularly polarized drive, both semimemtal systems\nimmediately generate Weyl node pairs whose types can be further controlled by\nthe driving amplitude and direction. The resultant phase diagrams demonstrate\nexperimental feasibilities.",
        "positive": "Probing Growth-Induced Anisotropic Thermal Transport in CVD Diamond\n  Membranes by Multi-frequency and Multi-spot-size Time-Domain\n  Thermoreflectance: The maximum output power of GaN-based high-electron mobility transistors is\nlimited by high channel temperature induced by localized self-heating which\ndegrades device performance and reliability. With generated heat fluxes within\nthese devices reaching magnitude close to ten times of that at the sun surface,\nchemical vapor deposition (CVD) diamond is an attractive candidate to aid in\nthe extraction of this heat in order to keep the operating temperatures of\nthese high power electronics as low as possible. Due to the observed\ninhomogeneous structure, CVD diamond membranes exhibit a 3D anisotropic thermal\nconductivity which may result in significantly different cooling performance\nfrom expected in a given application. In this work, time domain\nthermoreflectance (TDTR) is used to measure the thermal properties of an\n11.8-{\\mu}m CVD diamond membrane from its nucleation side. Starting with a spot\nsize diameter larger than the thickness of the membrane, measurements are made\nat various modulation frequencies from 1.2 MHz to 11.6 MHz to tune the heat\npenetration depth, and subsequently the part of diamond sampled by TDTR. We\ndivide the membrane into ten sublayers and assume isotropic thermal\nconductivity in each sublayer. From this, we observe a 2D gradient of the\ndepth-dependent thermal conductivity for this membrane. By measuring the same\nregion with a smaller spot size at multiple frequencies, the in-plane and\ncross-plane thermal conductivity are extracted respectively. Through this use\nof multiple spot sizes and modulation frequencies, the 3D anisotropic thermal\nconductivity of CVD diamond membrane is experimentally obtained by fitting the\nexperimental data to a thermal model. This work provides insight toward an\nimproved understanding of heat conduction inhomogeneity in CVD polycrystalline\ndiamond membrane that is important for applications of thermal management of\nhigh power electronics."
    },
    {
        "anchor": "Extending the Concept of Probability Flux: We develop the Husimi map for visualizing quantum wavefunctions using\ncoherent states as a measurement of the local phase space to produce a vector\nfield related to the probability flux. Adapted from the Husimi projection, the\nHusimi map is complimentary to the usual flux map, since they are identical for\nsmall coherent states. By improving our understanding of the flux operator and\noffering a robust and flexible alternative, we show how the Husimi projection\ncan provide a map to the classical dynamics underlying a quantum wavefunction.\nWe demonstrate its capabilities on bound systems with electromagnetic fields,\nas well as on open systems on and off resonance.",
        "positive": "Zero-field skyrmionic states and in-field edge-skyrmions induced by\n  boundary tuning: When magnetic skyrmions are moved via currents, they do not strictly travel\nalong the path of the current, instead their motion also gains a transverse\ncomponent. This so-called skyrmion Hall effect can be detrimental in potential\nskyrmion devices because it drives skyrmions towards the edge of their hosting\nmaterial where they face potential annihilation. Here we experimentally modify\na skyrmion model system - an atomic Pd/Fe bilayer on Ir(111) - by decorating\nthe film edge with ferromagnetic Co/Fe patches. Employing spin-polarized\nscanning tunneling microscopy, we demonstrate that this ferromagnetic rim\nprevents skyrmion annihilation at the film edge and stabilizes skyrmions and\ntarget states in zero field. Furthermore, in an external magnetic field the\nCo/Fe rim can give rise to skyrmions pinned to the film edge. Spin dynamics\nsimulations reveal how a combination of different attractive and repulsive\nskyrmion-edge interactions can induce such an edge-pinning effect for\nskyrmions."
    },
    {
        "anchor": "Graphene Q-switched, tunable fiber laser: We demonstrate a wideband-tunable Q-switched fiber laser exploiting a\ngraphene saturable absorber. We get ~2us pulses, tunable between 1522 and\n1555nm with up to~40nJ energy. This is a simple and low-cost light source for\nmetrology, environmental sensing and biomedical diagnostics.",
        "positive": "A renormalization group study of persistent current in a quasiperiodic\n  ring: We propose a real-space renormalization group approach for evaluating\npersistent current in a multi-channel quasiperiodic fibonacci tight-binding\nring based on a Green's function formalism. Unlike the traditional methods, the\npresent scheme provides a powerful tool for the theoretical description of\npersistent current with a very high degree of accuracy in large periodic and\nquasiperiodic rings, even in the micron scale range, which emphasizes the merit\nof this work."
    },
    {
        "anchor": "Electron-Hole Interference in an Inverted-Band Semiconductor Bilayer: Electron optics in the solid state promises new functionality in electronics\nthrough the possibility of realizing micrometer-sized interferometers, lenses,\ncollimators and beam splitters that manipulate electrons instead of light.\nUntil now, however, such functionality has been demonstrated exclusively in\none-dimensional devices, such as in nanotubes, and in graphene-based devices\noperating with p-n junctions. In this work, we describe a novel mechanism for\nrealizing electron optics in two dimensions. By studying a two-dimensional\nFabry-P\\'{e}rot interferometer based on a resonant cavity formed in an\nInAs/GaSb double quantum well using p-n junctions, we establish that\nelectron-hole hybridization in band-inverted systems can facilitate coherent\ninterference. With this discovery, we expand the field of electron optics to\nencompass materials that exhibit band inversion and hybridization, with the\npromise to surpass the performance of current state-of-the-art devices.",
        "positive": "Metal-terminated Graphene Nanoribbons: We have investigated structure, electronic, and magnetic properties of\nmetal-terminated zigzag graphene nanoribbons (M-ZGNRs) by first-principles\ncalculations. Two families of metal terminations are studied: (1) 3d-transition\nmetals (TMs) Fe, Co, and Ni and (2) noble metals (NMs) Cu, Ag, and Au. All\nsystems have spin-polarized edge states with antiferromagnetic (AFM) ordering\nbetween two edges, except Co-ZGNRs and Ni-ZGNRs which exhibit negligibly small\nenergy differences between AFM and ferromagnetic states with the given ribbon\nwidth. In the AFM state the TM terminations transform semiconducting ZGNRs into\nmetallic ones while the band gap remains in ZGNR with NM terminations.\nFerromagnetic states of M-ZGNRs with TM terminations show a high degree of spin\npolarization at the Fermi energy. We predict a large magnetoresistance in\nFe-ZGNR junctions with a low, uniform magnetic switching field."
    },
    {
        "anchor": "Temperature dependent screened electronic transport in gapped graphene: We report our theoretical calculations on the temperature and energy\ndependent electrical conductivity of gapped graphene within the framework of\nBoltzmann transport formalism. Since screening effects have known to be of\nvital importance in explaining the conductivity of gapless graphene therefore\nwe first worked out the behaviour of the temperature dependent polarization\nfunction for gapped graphene as a function of wave vector and band gap,\nrespectively. Polarization of gapped graphene has been compared with that of\ngapless graphene, bilayer graphene and 2DEG to see the effects of gap. It is\nfound that the gapped graphene polarization function exhibits a strong\ndependence on temperature, wave vector and band gap and the effect translates\nto the conductivity of gapped graphene. The nature of conductivity in gapped\ngraphene is observed to be non monotonic ranging from good to poor to semi\nconducting. We also find that the conductivity computed as a function of\ntemperature by averaging over quasi-particle energy significantly differs from\nthat computed at Fermi energy, suggesting that a notable contribution to\ntemperature dependent conductivity is made by electrons close to the Fermi\nlevel.",
        "positive": "Theory of current-driven dynamics of spin textures on a surface of\n  topological insulators: Spin-transfer torque is one of the important physical quantities to\nunderstand for successful application of topological insulators to spintronics.\nIn this paper, we present analytical expressions of the spin-transfer torques\non a surface of a magnetic topological insulator by including the higher-order\ncontributions of momentum, $k^2$-term and the hexagonal warping. We obtain six\ndifferent types of the spin-transfer torque including both the field-like and\nthe damping-like torques; the four of them appear only when the higher-order\nmomentum contributions are included. In addition, we discuss the dynamics of\nmagnetic skyrmions driven by the spin-transfer torques on the surface of the\ntopological insulator. Unlike the skyrmion dynamics in conventional metals, we\nfind that the dynamics significantly depends on the internal structure of\nmagnetic textures."
    },
    {
        "anchor": "Reply to Wernsdorfer's post: \"Correspondence on: Quantum interference of\n  tunnel trajectories between states of different spin lenght in a dimeric\n  molecular nanomagnet\": We present here an exact version of our response (dated April 27) to\nWernsdorfer's correspondence submitted to Nature Physics on March 31, 2008.\nAfter consultation with a referee, Nature Physics chose not publish any part of\nthis exchange. We would therefore like to point out that our original study has\nnow been considered favorably by four separate referees chosen by Nature\nPhysics. Unfortunately, Wernsdorfer subsequently posted two further variations\nof his correspondence on this archive (arXiv:0804.1246v1 and\narXiv:0804.1246v2). We note that aspects of the most recent posting (dated\nafter submission of our response) contradict the version submitted to Nature\nPhysics. However, none of the revisions add weight to Wernsdorfer's original\ncorrespondence.",
        "positive": "Model of lateral diffusion in ultrathin layered films: We consider the diffusion of markers in a layered medium, with the lateral\ndiffusion coefficient being the function of hight. We show that the probability\ndensity of the lateral displacements follows one-dimensional Batchelor's\nequation with time-dependent diffusion coefficient governed by the particles'\nredistribution in height. For the film of a finite thickness the resulting mean\nsquared displacement exhibits superdiffusion at short times and crosses over to\nnormal diffusion at long times. The approach is used for description of\nexperimental results on inhomogeneous molecular diffusion in thin liquid films\ndeposited on solid surfaces."
    },
    {
        "anchor": "Free-energy landscapes in magnetic systems from metadynamics: Knowledge of free energy barriers separating different states is critically\nimportant for assessment of long-term stability of information stored in\nmagnetic devices. This information, however, is not directly accessible by\nstandard simulations of microscopic models because of the ubiquitous time-scale\nproblem, related to the fact that the transitions among different free energy\nminima have character of rare events. Here we show that by employing the\nmetadynamics algorithm based on suitably chosen collective variables, namely\nhelicity and circulation, it is possible to reliably recover the free energy\nlandscape. We demonstrate the effectiveness of the new approach on the example\nof vortex nucleation process in magnetic nanodot with lowered spatial symmetry.\nWith the help of reconstructed free energy surfaces (FES) we show the origin of\nthe symmetry broken vortex nucleation, where one polarity of the nucleated\nvortex core is preferred, even though only in-plane magnetic field is present.",
        "positive": "Microscopic theory of photon-induced energy, momentum, and angular\n  momentum transport in the nonequilibrium regime: We set up a general microscopic theory for the transfer of energy, momentum,\nand angular momentum mediated by photons. Using the nonequilibrium Green's\nfunction method, we propose a unified Meir-Wingreen formalism for the energy\nemitted, force experienced, and torque experienced by the objects due to the\nfluctuating electromagnetic field. Our theory does not require the local\nthermal equilibrium that is the central assumption of the conventional theory\nof fluctuational electrodynamics (FE). The obtained formulas are valid for\narbitrary objects as well as the environment without the requirement of\nreciprocity. To show the capability of our microscopic theory, we apply the\ngeneral formulas to transport problems of graphene edges in both equilibrium\nand nonequilibrium situations. We show the local equilibrium energy radiation\nof graphene obeys the well-known $T^4$ law with a converged theoretical\nemissivity of 2.058$\\%$. In the ballistic nonequilibrium situation driven by\nchemical potential biases, we observe nonzero results for force and torque from\nthe graphene edges, which go beyond the predictive ability of the FE theory.\nOur method is general and efficient for large systems, which paves the way for\nstudying more complex transport phenomena in the nonequilibrium regime."
    },
    {
        "anchor": "Coherent transport through a double donor system in silicon: Quantum coherence is of crucial importance for the applicability of donor\nbased quantum computing. In this Letter we describe the observation of the\ninterference of conduction paths induced by two donors in a nano-MOSFET\nresulting in a Fano resonance. This demonstrates the coherent exchange of\nelectrons between two donors. In addition, the phase difference between the two\nconduction paths can be tuned by means of a magnetic field, in full analogy to\nthe Aharonov-Bohm effect.",
        "positive": "Transport through quantum spin Hall insulator/metal junctions in\n  graphene ribbons: Quantum spin Hall insulator/metal interfaces are formed in graphene ribbons\nwith intrinsic spin-orbit coupling by selectively doping two regions creating a\npotential step. For a clean graphene ribbon, the transmission of the\ntopological edge states through a n-n or p-p junction is perfect irrespective\nof the ribbon termination, width, and potential step parameters due to the\northogonality of incoming and outgoing edge channels. This is shown numerically\nfor an arbitrary crystallographic orientation of the ribbon and proven\nanalytically for zigzag and metallic armchair boundary conditions. In\ndisordered ribbons, the orthogonality between left- and right-movers is in\ngeneral destroyed and backscattering sets in. However, transmission approaches\none by increasing the ribbon's width, even in the presence of strong edge\nroughness."
    },
    {
        "anchor": "Correlation-mediated processes for electron-induced switching between\n  Neel states of Fe anti-ferromagnetic chains: The controlled switching between two quasi-stable Neel states in adsorbed\nanti-ferromagnetic Fe chains has recently been achieved by Loth et al [Science\n335, 196 (2012)]. In order to rationalize their data, we evaluate the rate of\ntunneling electron-induced switching between the N\\'eel states. Good agreement\nis found with the experiment permitting us to identify three switching\nmechanisms: (i) low-bias direct electron-induced transitions, (ii)\nintermediate-bias switching via spin-wave-like excitation, and (iii) high-bias\ntransitions mediated by domain wall formation. Spin correlations in the\nanti-ferromagnetic chains are the switching driving force leading to a marked\nchain-size dependence.",
        "positive": "Enhanced Eshelby Twist on Thin Wurtzite InP Nanowires and Measurement of\n  Local Crystal Rotation: We have performed a detailed study of the lattice distortions of InP wurtzite\nnanowires containing an axial screw dislocation. Eshelby predicted that this\nkind of system should show a crystal rotation due to the dislocation induced\ntorque. We have measured the twisting rate and the dislocation Burgers vector\non individual wires, revealing that nanowires with a 10-nm radius have a twist\nup to 100% larger than estimated from elasticity theory. The strain induced by\nthe deformation has a Mexican-hat-like geometry, which may create a tube-like\npotential well for carriers."
    },
    {
        "anchor": "Phonon Heat Conduction in Corrugated Silicon Nanowires Below the Casimir\n  Limit: The thermal conductance of straight and corrugated monocrystalline silicon\nnanowires has been measured between 0.3 K and 5 K. The difference in the\nthermal transport between corrugated nanowires and straight ones demonstrates a\nstrong reduction in the mean free path of the phonons. This averaged mean free\npath is remarkably smaller than the smaller diameter of the nanowire,\nevidencing a phonon thermal transport reduced below the Casimir limit. Monte\nCarlo simulations highlight that this effect can be attributed to significant\nmultiple scattering of ballistic phonons occuring on the corrugated surfaces.\nThis result suggests an original approach to transforming a monocrystalline\nmaterial into a phonon glass.",
        "positive": "Hall Effect Induced by Topologically Trivial Target Skyrmions: Electrons moving through a noncoplanar magnetic texture acquire a Berry\nphase, which can be described as an effective magnetic field. This effect is\nknown as the topological Hall effect and has been observed in topological spin\ntextures. Motivated by recent experimental realizations, here we study the Hall\neffect in a nontopological magnetic texture known as a target skyrmion. We\nstart from a simplified semiclassical picture and show that the Hall signal is\na nonmonotonic function of both the electronic energy and target skyrmion\nradius. That observation carries over to the fully quantum mechanical treatment\nin a Landauer-B\\\"uttiker formalism in a mesoscopic setting. Our conclusion\nchallenges the popular opinion in the community that the Hall effect in such\nstructures necessarily requires a nonzero skyrmion number."
    },
    {
        "anchor": "Finite-size scaling in a 2D disordered electron gas with spectral nodes: We study the DC conductivity of a weakly disordered 2D electron gas with two\nbands and spectral nodes, employing the field theoretical version of the\nKubo--Greenwood conductivity formula. Disorder scattering is treated within the\nstandard perturbation theory by summing up ladder and maximally crossed\ndiagrams. The emergent gapless (diffusion) modes determine the behavior of the\nconductivity on large scales. We find a finite conductivity with an\nintermediate logarithmic finite-size scaling towards smaller conductivities but\ndo not obtain the logarithmically divergence of the weak-localization approach.\nOur results agree with the experimentally observed logarithmic scaling of the\nconductivity in graphene with the formation of a plateau near $e^2/\\pi h$.",
        "positive": "Designing a highly efficient graphene quantum spin heat engine: We design a quantum spin heat engine using spin polarized ballistic modes\ngenerated in a strained graphene monolayer doped with a magnetic impurity. We\nobserve remarkably large efficiency and large thermoelectric figure of merit\nboth for the charge as well as spin variants of the quantum heat engine. This\nsuggests the use of this device as a highly efficient quantum heat engine for\ncharge as well as spin-based transport. Further, a comparison is drawn between\nthe device characteristics of a graphene spin heat engine against a quantum\nspin Hall heat engine. The reason being edge modes because of their origin\nshould give much better performance. In this respect, we observe our\ngraphene-based spin heat engine can almost match the performance\ncharacteristics of a quantum spin Hall heat engine. Finally, we show that a\npure spin current can be transported in our device in absence of any charge\ncurrent."
    },
    {
        "anchor": "Ballistic electron spectroscopy: We demonstrate the feasibility of ballistic electron spectroscopy as a new\ntool for mesoscopic physics. A quantum dot is utilised as an energy-selective\ndetector of non-equilibrium ballistic electrons injected into a two-dimensional\nelectron system. In this paper we use a second quantum dot as the electron\ninjector to evaluate the scheme. We propose an application in the study of\ninteracting 1D and 0D systems.",
        "positive": "Quantum mechanical analysis of nonlinear optical response of interacting\n  graphene nanoflakes: We propose a distant-neighbor quantum-mechanical (DNQM) approach to study the\nlinear and nonlinear optical properties of graphene nanoflakes (GNFs). In\ncontrast to the widely used tight-binding description of the electronic states\nthat considers only the nearest-neighbor coupling between the atoms, our\napproach is more accurate and general, as it captures the electron-core\ninteractions between all atoms in the structure. Therefore, as we demonstrate,\nthe DNQM approach enables the investigation of the optical coupling between two\nclosely separated, but chemically unbound GNFs. We also find that the optical\nresponse of GNFs depends crucially on their shape, size, and symmetry\nproperties. Specifically, increasing the size of nanoflakes is found to shift\ntheir accommodated quantum plasmon oscillations to lower frequency.\nImportantly, we show that by embedding a cavity into GNFs, one can change their\nsymmetry properties, tune their optical properties, or enable otherwise\nforbidden second-harmonic generation processes."
    },
    {
        "anchor": "A Magic Ratio Rule for Beginners: a Chemist's Guide to Quantum\n  Interference in Molecules: This overview will give a glimpse into chemical design principles for\nexploiting quantum interference (QI) effects in molecular-scale devices. Direct\nobservation of room temperature QI in single-molecule junctions has stimulated\ngrowing interest in fabrication of tailor-made molecular electronic devices.\nHerein, we outline a new conceptual advance in the scientific understanding and\ntechnological know-how necessary to control QI effects in single molecules by\nchemical modification. We start by discussing QI from a chemical viewpoint and\nthen describe a new magic ratio rule (MRR), which captures a minimal\ndescription of connectivity-driven charge transport and provides a useful\nstarting point for chemists to design appropriate molecules for molecular\nelectronics with desired functions. The MRR predicts conductance ratios, which\nare solely determined by QI within the core of polycyclic aromatic hydrocarbons\n(PAHs). The manifestations of QI and related quantum circuit rules for\nmaterials discovery are direct consequences of the key concepts of weak\ncoupling, locality, connectivity, mid-gap transport and phase coherence in\nsingle-molecule junctions.",
        "positive": "Time-dependent quantum transport and power-law decay of the transient\n  current in a nano-relay and nano-oscillator: Time-dependent nonequilibrium Green's functions are used to study electron\ntransport properties in a device consisting of two linear chain leads and a\ntime-dependent interleads coupling that is switched on non-adiabatically. We\nderive a numerically exact expression for the particle current and examine its\ncharacteristics as it evolves in time from the transient regime to the\nlong-time steady-state regime. We find that just after switch-on the current\ninitially overshoots the expected long-time steady-state value, oscillates and\ndecays as a power law, and eventually settles to a steady-state value\nconsistent with the value calculated using the Landauer formula. The power-law\nparameters depend on the values of the applied bias voltage, the strength of\nthe couplings, and the speed of the switch-on. In particular, the oscillating\ntransient current decays away longer for lower bias voltages. Furthermore, the\npower-law decay nature of the current suggests an equivalent series\nresistor-inductor-capacitor circuit wherein all of the components have\ntime-dependent properties. Such dynamical resistive, inductive, and capacitive\ninfluences are generic in nano-circuites where dynamical switches are\nincorporated. We also examine the characteristics of the dynamical current in a\nnano-oscillator modeled by introducing a sinusoidally modulated interleads\ncoupling between the two leads. We find that the current does not strictly\nfollow the sinusoidal form of the coupling. In particular, the maximum current\ndoes not occur during times when the leads are exactly aligned. Instead, the\ntimes when the maximum current occurs depend on the values of the bias\npotential, nearest-neighbor coupling, and the interleads coupling."
    },
    {
        "anchor": "Self-induction and magnetic effects in electron transport through a\n  photon cavity: We explore higher order dynamical effects in the transport through a\ntwo-dimensional nanoscale electron system embedded in a three-dimensional\nfar-infrared photon cavity. The nanoscale system is considered to be a short\nquantum wire with a single circular quantum dot defined in a GaAs\nheterostructure. The whole system, the external leads and the central system\nare placed in a constant perpendicular magnetic field. The Coulomb interaction\nof the electrons, the para- and diamagnetic electron-photon interactions are\nall treated by a numerically exact diagonalization using step-wise truncations\nof the appropriate many-body Fock spaces. We focus on the difference in\ntransport properties between a description within an electric dipole\napproximation and a description including all higher order terms in a single\nphoton mode model. We find small effects mostly caused by an electrical\nquadrupole and a magnetic dipole terms that depend strongly on the polarization\nof the cavity field with respect to the transport direction and the photon\nenergy. When the polarization is aligned along the transport direction we find\nindications of a weak self-induction that we analyze and compare to the\nclassical counterpart, and the self-energy contribution of high-order\ninteraction terms to the states the electrons cascade through on their way\nthrough the system. Like expected the electron-photon interaction is well\ndescribed in the dipole approximation when it is augmented by the lowest order\ndiamagnetic part for a nanoscale system in a cavity in an external magnetic\nfield.",
        "positive": "Linear response theory of Josephson junction arrays in a microwave\n  cavity: Recent experiments on Josephson junction arrays (JJAs) in microwave cavities\nhave opened up a new avenue for investigating the properties of these devices\nwhile minimising the amount of external noise coming from the measurement\napparatus itself. These experiments have already shown promise for probing\nmany-body quantum effects in JJAs. In this work, we develop a general\ntheoretical description of such experiments by deriving a quantum phase model\nfor planar JJAs containing quantized vortices. The dynamical susceptibility of\nthis model is calculated for some simple circuits, and signatures of the\ninjection of additional vortices are identified. The effects of decoherence are\nconsidered via a Lindblad master equation."
    },
    {
        "anchor": "The Origin of Antibunching in Resonance Fluorescence: Epitaxial quantum dots have emerged as one of the best single-photon sources,\nnot only for applications in photonic quantum technologies but also for testing\nfundamental properties of quantum optics. One intriguing observation in this\narea is the scattering of photons with subnatural linewidth from a two-level\nsystem under resonant continuous wave excitation. In particular, an open\nquestion is whether these subnatural linewidth photons exhibit simultaneously\nantibunching as an evidence of single-photon emission. Here, we demonstrate\nthat this simultaneous observation of subnatural linewidth and antibunching is\nnot possible with simple resonant excitation. First, we independently confirm\nsingle-photon character and subnatural linewidth by demonstrating antibunching\nin a Hanbury Brown and Twiss type setup and using high-resolution spectroscopy,\nrespectively. However, when filtering the coherently scattered photons with\nfilter bandwidths on the order of the homogeneous linewidth of the excited\nstate of the two-level system, the antibunching dip vanishes in the correlation\nmeasurement. Our experimental work is consistent with recent theoretical\nfindings, that explain antibunching from photon-interferences between the\ncoherent scattering and a weak incoherent signal in a skewed squeezed state.",
        "positive": "Ground state and polarization of an hydrogen-like atom near a Weyl\n  semimetal: In this paper we study the effects of a topological Weyl semimetal (WSM) upon\nthe ground state and polarization of an hydrogen-like atom near its surface.\nThe WSM is assumed to be in the equilibrium state and at the neutrality point,\nsuch that the interaction between the atomic charges and the material is fully\ndescribed (in the non retarded regime) by axion electrodynamics, which is an\nexperimentally observable signature of the anomalous Hall effect in the bulk of\nthe WSM. The atom-WSM interaction provides additional contributions to the\nCasimir-Polder potential thus modifying the energy spectra and wave function,\nwhich now became distance dependent. Using variational methods, we solve the\ncorresponding Schr\\\"{o}dinger equation for the atomic electron. The ground\nstate and the polarization are analyzed as a function of the atom-surface\ndistance, and we directly observe the effects of the nontrivial topology of the\nmaterial by comparing our results with that of a topologically trivial sample.\nWe also study the impact of the medium's permittivity by assuming a hydrogen\natom in vacuum, and a donor impurity in the semiconductors gallium arsenide\n(GaAs) and gallium phosphide (GaP). We found that the topological interaction\nbehaves as an effective-attractive charge so that the electronic cloud tends to\nbe polarized to the interface of materials. Moreover, the loss of wave-function\nnormalization is interpreted as a critical location from below which the bound\nstate is broken."
    },
    {
        "anchor": "Characterization of a microwave frequency resonator via a nearby quantum\n  dot: We present measurements of a hybrid system consisting of a microwave\ntransmission-line resonator and a lateral quantum dot defined on a GaAs\nheterostructure. The two subsystems are separately characterized and their\ninteraction is studied by monitoring the electrical conductance through the\nquantum dot. The presence of a strong microwave field in the resonator is found\nto reduce the resonant conductance through the quantum dot, and is attributed\nto electron heating and modulation of the dot potential. We use this\ninteraction to demonstrate a measurement of the resonator transmission spectrum\nusing the quantum dot.",
        "positive": "Modeling techniques for quantum cascade lasers: Quantum cascade lasers are unipolar semiconductor lasers covering a wide\nrange of the infrared and terahertz spectrum. Lasing action is achieved by\nusing optical intersubband transitions between quantized states in specifically\ndesigned multiple-quantum-well heterostructures. A systematic improvement of\nquantum cascade lasers with respect to operating temperature, efficiency and\nspectral range requires detailed modeling of the underlying physical processes\nin these structures. Moreover, the quantum cascade laser constitutes a\nversatile model device for the development and improvement of simulation\ntechniques in nano- and optoelectronics. This review provides a comprehensive\nsurvey and discussion of the modeling techniques used for the simulation of\nquantum cascade lasers. The main focus is on the modeling of carrier transport\nin the nanostructured gain medium, while the simulation of the optical cavity\nis covered at a more basic level. Specifically, the transfer matrix and finite\ndifference methods for solving the one-dimensional Schr\\\"odinger equation and\nSchr\\\"odinger-Poisson system are discussed, providing the quantized states in\nthe multiple-quantum-well active region. The modeling of the optical cavity is\ncovered with a focus on basic waveguide resonator structures. Furthermore,\nvarious carrier transport simulation methods are discussed, ranging from basic\nempirical approaches to advanced self-consistent techniques. The methods\ninclude empirical rate equation and related Maxwell-Bloch equation approaches,\nself-consistent rate equation and ensemble Monte Carlo methods, as well as\nquantum transport approaches, in particular the density matrix and\nnon-equilibrium Green's function (NEGF) formalism. The derived scattering rates\nand self-energies are generally valid for n-type devices based on\none-dimensional quantum confinement, such as quantum well structures."
    },
    {
        "anchor": "WSe2 light-emitting tunneling transistors with enhanced brightness at\n  room temperature: Monolayers of molybdenum and tungsten dichalcogenides are direct bandgap\nsemiconductors, which makes them promising for opto-electronic applications. In\nparticular, van der Waals heterostructures consisting of monolayers of MoS2\nsandwiched between atomically thin hexagonal boron nitride (hBN) and graphene\nelectrodes allows one to obtain light emitting quantum wells (LEQWs) with\nlow-temperature external quantum efficiency (EQE) of 1%. However, the EQE of\nMoS2 and MoSe2-based LEQWs shows behavior common for many other materials: it\ndecreases fast from cryogenic conditions to room temperature, undermining their\npractical applications. Here we compare MoSe2 and WSe2 LEQWs. We show that the\nEQE of WSe2 devices grows with temperature, with room temperature EQE reaching\n5%, which is 250x more than the previous best performance of MoS2 and MoSe2\nquantum wells in ambient conditions. We attribute such a different temperature\ndependences to the inverted sign of spin-orbit splitting of conduction band\nstates in tungsten and molybdenum dichalcogenides, which makes the\nlowest-energy exciton in WSe2 dark.",
        "positive": "Quantum-metric-enabled exciton condensate in double twisted bilayer\n  graphene: Flat-band systems are a promising platform for realizing exotic collective\nground states with spontaneously broken symmetry because the electron-electron\ninteractions dominate over the kinetic energy. A collective ground state of\nparticular interest is the chased after exciton condensate (EC). However, in\nflat band systems other collective ground states can compete with an EC phase,\nand the conventional treatment of the effect of thermal and quantum\nfluctuations predicts the EC phase should be unstable. Here, using double\ntwisted bilayer graphene (TBLG) heterostructures as an example, we show that\nfor realistic interaction strengths the EC phase is favored with respect to\nother TBLG's phases -- orbital magnetism and superconductivity -- when the\nTBLGs have opposite doping, and that the quantum metric of the Bloch wave\nfunctions stabilizes the EC, reversing the conclusion that would be drawn from\nthe conventional approach in which quantum metric contributions are neglected.\nOur results suggest that the quantum metric plays a critical role in\ndetermining the stability of exciton condensates in double layers formed by\nsystems with flat-bands."
    },
    {
        "anchor": "Optical analogues of quantum chirality: We show that the quantum chirality of charge carriers in graphene can be\nmimicked in optical structures. More precisely, we demonstrate that the\nparticular form of the transmission coefficient at an interface in graphene\nbetween regions with different parameters can be retrieved in optics in either\nisotropic, gyrotropic and electro-optic materials or in complex conjugate\nmaterials. Quantitative analogies are found, at least in some parameter range,\nbetween optical and quantum parameters for which the transmission coefficient\nis similar in the optical and quantum cases, and hence the optical fields and\nquantum wavefunctions propagate in a similar manner.",
        "positive": "Bulk ReSe2: record high refractive index and biaxially anisotropic\n  material for all-dielectric nanophotonics: We show that bulk rhenium diselenide, ReSe2 is characterized by record high\nvalue of the refractive index exceeding 5 in near-infrared frequency range. We\nuse back focal plane reflection spectroscopy to extract the components of the\nReSe2 permittivity tensor and reveal its extreme biaxial anisotropy. We also\ndemonstrate the good agreement between the experimental data and the\npredictions of the density functional theory. The combination of the large\nrefractive index and giant optical anisotropy makes ReSe2 a perspective\nmaterial for all-dielectric nanophotonics in the near-infrared frequency range."
    },
    {
        "anchor": "Hot-carrier transfer across a nanoparticle-molecule junction: The\n  importance of orbital hybridization and level alignment: While direct hot-carrier transfer can increase photo-catalytic activity, it\nis difficult to discern experimentally and competes with several other\nmechanisms. To shed light on these aspects, here, we model from first\nprinciples hot-carrier generation across the interface between plasmonic\nnanoparticles and a CO molecule. The hot-electron transfer probability depends\nnon-monotonically on the nanoparticle-molecule distance and can be effective at\nlong distances, well outside the region of chemisorption; hot-hole transfer on\nthe other hand is limited to shorter distances. These observations can be\nexplained by the energetic alignment between molecular and nanoparticle states\nas well as the excitation frequency. The hybridization of the molecular\norbitals is the key predictor for hot-carrier transfer in these systems,\nemphasizing the need to include the effects of ground state hybridization for\naccurate predictions. Finally, we show a non-trivial dependence of the\nhot-carrier distribution on the excitation energy, which could be exploited\nwhen optimizing photo-catalytic systems.",
        "positive": "Circular photon drag effect in bulk tellurium: The circular photon drag effect is observed in a bulk semiconductor. The\nphotocurrent caused by a transfer of both translational and angular momenta of\nlight to charge carriers is detected in tellurium in the mid-infrared frequency\nrange. Dependencies of the photocurrent on the light polarization and on the\nincidence angle agree with the symmetry analysis of the circular photon drag\neffect. Microscopic models of the effect are developed for both intra- and\ninter-subband optical absorption in the valence band of tellurium. The shift\ncontribution to the circular photon drag current is calculated. An observed\ndecrease of the circular photon drag current with increase of the photon energy\nis explained by the theory for inter-subband optical transitions. Theoretical\nestimates of the circular photon drag current agree with the experimental data."
    },
    {
        "anchor": "Thermal Uhlmann Chern number from the Uhlmann connection for extracting\n  topological properties of mixed states: The Berry phase is a geometric phase of a pure state when the system is\nadiabatically transported along a loop in its parameter space. The concept of\ngeometric phase has been generalized to mixed states by the so called Uhlmann\nphase. However, the Uhlmann phase is constructed from the Uhlmann connection\nthat possesses a well defined global section. This property implies that the\nUhlmann connection is topologically trivial and as a consequence, the\ncorresponding Chern character vanishes. We propose modified Chern character\nwhose integral gives the thermal Uhlmann Chern number, which is related to the\nwinding number of the mapping defined by the Hamiltonian. Therefore, the\nthermal Uhlmann Chern number reflects the topological properties of the\nunderlying Hamiltonian of a mixed state. By including the temperature\ndependence in the volume integral, we also introduce the non-topological\nthermal Uhlmann Chern number which varies with temperature but is not quantized\nat finite temperatures. We illustrate the applications to a two-band model and\na degenerate four-band model.",
        "positive": "Electronic structure of InAs quantum dots with GaAsSb strain reducing\n  layer: Localization of holes and its effect on the optical properties: The electronic structure of InAs quantum dots covered with the GaAs(1-y)Sb(y)\nstrain reducing layer has been studied using the k.p theory. We explain\nprevious experimental observations of the red shift of the photoluminescence\nemission with increasing y and its blue shift with increasing excitation power.\nFor y>0.19 type-II dots are formed with holes localized in the GaAsSb close to\nthe dot base; two segments at opposite sides of the dot, forming molecular-like\nstates, result from the piezoelectric field. We also propose an experiment that\ncould be used to identify the hole localization using a vertical electric\nfield."
    },
    {
        "anchor": "Engineering the hole confinement for CdTe-based quantum dot molecules: We demonstrate an efficient method to engineer the quantum confinement in a\nsystem of two quantum dots grown in a vertical stack. We achieve this by using\nmaterials with a different lattice constant for the growth of the outer and\ninner barriers. We monitor the resulting dot morphology with transmission\nelectron microscopy studies and correlate the results with ensemble quantum dot\nphotoluminescence. Furthermore, we embed the double quantum dots into diode\nstructures and study photoluminescence as a function of bias voltage. We show\nthat in properly engineered structures, it is possible to achieve a resonance\nof the hole states by tuning the energy levels with electric field. At the\nresonance, we observe signatures of a formation of a molecular state,\nhybridized over the two dots.",
        "positive": "Exciton scattering model of carrier multiplication in semiconductor\n  nanocrystals: The effect of carrier multiplication (CM) in semiconductor nanocrystals is\nsystematically treated by employing an exciton scattering approach. Using\nprojection operators, we reduce the Coulomb coupled multi-exciton dynamics to\nscattering dynamics in the space spanning both single- and bi-exciton states.\nWe derive a closed set of equations determining the scattering matrix elements.\nThis allows us to interpret CM dynamics as a series of odd-order interband\nscattering events. Using the time-dependent density matrix formalism, we\nprovide a rigorous description of the CM dynamics induced by a finite-time pump\npulse. Within this approach, both processes of single- and bi-exciton\nphotogeneration and the consequent population relaxation are treated on the\nsame footing. This approach provides a framework for numerical calculations and\nfor comparisons of the quantum efficiencies associated with each process. For\napplications, the limit of weak interband Coulomb coupling is considered.\nFinally, we demonstrate that three previously used theoretical models can be\nrecovered as limiting cases of our exciton scattering model."
    },
    {
        "anchor": "Shot Noise of a Tunnel Junction Displacement Detector: We study quantum-mechanically the frequency-dependent current noise of a\ntunnel-junction coupled to a nanomechanical oscillator. The cases of both DC\nand AC voltage bias are considered, as are the effects of intrinsic oscillator\ndamping. The dynamics of the oscillator can lead to large signatures in the\nshot noise, even if the oscillator-tunnel junction coupling is too weak to\nyield an appreciable signature in the average current. Moreover, the\nmodification of the shot noise by the oscillator cannot be fully explained by a\nsimple classical picture of a fluctuating conductance.",
        "positive": "High-Resolution Tunneling Spectroscopy of Fractional Quantum Hall States: Strong interaction among electrons in two-dimensional systems in the presence\nof high magnetic fields gives rise to fractional quantum Hall (FQH) states that\nhost quasi-particles with fractional charge and statistics. We perform\nhigh-resolution scanning tunneling microscopy and spectroscopy of FQH states in\nultra-clean Bernal-stacked bilayer graphene (BLG) devices. Our experiments show\nthat the formation of FQH states coincides with the appearance of sharp\nexcitations in tunneling experiments that have been predicted to occur for\nelectron fractionalizing into bound states of quasi-particles. From these\nmeasurements and their comparison to theoretical calculations, we find large\nlocal energy gaps that protect quasi-particles of FQH states predicted to host\nnon-abelian anyons, making BLG an ideal setting for the exploration of these\nnovel quasi-particles. STM studies not only provide a way to characterize the\nbulk properties of FQH states in the absence of disorder but also reveal\nprevious undiscovered states in such ultra-clean samples."
    },
    {
        "anchor": "Transport in finite graphene samples: We study the DC transport of finite graphene samples with random gap. Using\nDirac fermions to describe the low-energy physics near the Dirac point, we\nemploy a generalized Drude form for the conductivity. The latter is constant\nfor a vanishing average gap but always decreases with increasing sample size\nfor a nonzero average gap. The asymptotic conductivity of the infinite sample\nis either nonzero if the average gap is smaller than a critical value or zero\notherwise. Our results are in agreement with recent numerical calculations of\nBardarson et al..",
        "positive": "Microwave response of an NS ring coupled to a superconducting resonator: A long phase coherent normal (N) wire between superconductors (S) is\ncharacterized by a dense phase dependent Andreev spectrum . We probe this\nspectrum in a high frequency phase biased configuration, by coupling an NS ring\nto a multimode superconducting resonator. We detect a dc flux and frequency\ndependent response whose dissipative and non dissipative components are related\nby a simple Debye relaxation law with a characteristic time of the order of the\ndiffusion time through the N part of the ring. The flux dependence exhibits\n$h/2e$ periodic oscillations with a large harmonics content at temperatures\nwhere the Josephson current is purely sinusoidal. This is explained considering\nthat the populations of the Andreev levels are frozen on the time-scale of the\nexperiments."
    },
    {
        "anchor": "Introduction to abelian and non-abelian anyons: In this set of lectures, we will start with a brief pedagogical introduction\nto abelian anyons and their properties. This will essentially cover the\nbackground material with an introduction to basic concepts in anyon physics,\nfractional statistics, braid groups and abelian anyons. The next topic that we\nwill study is a specific exactly solvable model, called the toric code model,\nwhose excitations have (mutual) anyon statistics. Then we will go on to discuss\nnon-abelian anyons, where we will use the one dimensional Kitaev model as a\nprototypical example to produce Majorana modes at the edge. We will then\nexplicitly derive the non-abelian unitary matrices under exchange of these\nMajorana modes.",
        "positive": "Strongly Anisotropic Electronic Transport at Landau Level Filling Factor\n  $\u03bd= 9/2$ and $\u03bd= 5/2$ Under Tilted Magnetic Field: We have investigated the influence of an increasing in-plane magnetic field\non the states at half-filling of Landau levels ($\\nu$ = 11/2, 9/2, 7/2, and\n5/2) of a two-dimensional electron system. In the electrically anisotropic\nphase at $\\nu$ = 9/2 and 11/2 an in-plane magnetic field of $\\sim$ 1-2 T\novercomes its initial pinning to the crystal lattice and {\\it reorient} this\nphase. In the initially isotropic phases at $\\nu$ = 5/2 and 7/2 an in-plane\nmagnetic field {\\it induces} a strong electrical anisotropy. In all cases, for\nhigh in-plane fields, the high resistance axis is parallel to the direction of\nthe in-plane field."
    },
    {
        "anchor": "Einstein-de Haas torque as a discrete spectroscopic probe allows\n  nanomechanical measurement of a magnetic resonance: The Einstein-de Haas (EdH) effect is a fundamental, mechanical consequence of\nany temporal change of magnetism in an object. EdH torque results from\nconserving the object's total angular momentum: the angular momenta of all the\nspecimen's magnetic moments, together with its mechanical angular momentum.\nAlthough the EdH effect is usually small and difficult to observe, it increases\nin magnitude with detection frequency. We explore the frequency-dependence of\nEdH torque for a thin film permalloy microstructure by employing a ladder of\nflexural beam modes (with five distinct resonance frequencies spanning from 3\nto 208 MHz) within a nanocavity optomechanical torque sensor via magnetic\nhysteresis curves measured at mechanical resonances. At low DC fields the\ngyrotropic resonance of a magnetic vortex spin texture overlaps the 208 MHz\nmechanical mode. The massive EdH mechanical torques arising from this\nco-resonance yield a fingerprint of vortex core pinning and depinning in the\nsample. The experimental results are discussed in relation to mechanical\ntorques predicted from both macrospin (at high DC magnetic field) and\nfinite-difference solutions to the Landau-Lifshitz-Gilbert (LLG) equation. A\nglobal fit of the LLG solutions to the frequency-dependent data reveals a\nstatistically significant discrepancy between the experimentally observed and\nsimulated torque phase behaviours at spin texture transitions that can be\nreduced through the addition of a time constant to the conversion between\nmagnetic cross-product torque and mechanical torque, constrained by experiment\nto be in the range of 0.5 - 4 ns.",
        "positive": "Hybridization at superconductor-semiconductor interfaces: Hybrid superconductor-semiconductor devices are currently one of the most\npromising platforms for realizing Majorana zero modes. Their topological\nproperties are controlled by the band alignment of the two materials, as well\nas the electrostatic environment, which are currently not well understood.\nHere, we pursue to fill in this gap and address the role of band bending and\nsuperconductor-semiconductor hybridization in such devices by analyzing a gated\nsingle Al-InAs interface using a self-consistent Schrodinger-Poisson approach.\nOur numerical analysis shows that the band bending leads to an interface\nquantum well, which localizes the charge in the system near the\nsuperconductor-semiconductor interface. We investigate the hybrid band\nstructure and analyze its response to varying the gate voltage and thickness of\nthe Al layer. This is done by studying the hybridization degrees of the\nindividual subbands, which determine the induced pairing and effective\n$g$-factors. The numerical results are backed by approximate analytical\nexpressions which further clarify key aspects of the band structure. We find\nthat one can obtain states with strong superconductor-semiconductor\nhybridization at the Fermi energy, but this requires a fine balance of\nparameters, with the most important constraint being on the width of the Al\nlayer. In fact, in the regime of interest, we find an almost periodic\ndependence of the hybridization degree on the Al width, with a period roughly\nequal to the thickness of an Al monolayer. This implies that disorder and shape\nirregularities, present in realistic devices, may play an important role for\naveraging out this sensitivity and, thus, may be necessary for stabilizing the\ntopological phase."
    },
    {
        "anchor": "Self-reset schemes for Magnetic domain wall-based neuron: Spintronic artificial spiking neurons are promising due to their ability to\nclosely mimic the leaky integrate-and-fire (LIF) dynamics of the biological LIF\nspiking neuron. However, the neuron needs to be reset after firing. Few of the\nspintronic neurons that have been proposed in the literature discuss the reset\nprocess in detail. In this article, we discuss the various schemes to achieve\nthis reset in a magnetic domain wall (DW) based spintronic neuron in which the\nposition of the DW represents the membrane potential. In all the spintronic\nneurons studied, the neuron enters a refractory period and is reset when the DW\nreaches a particular position. We show that the self-reset operation in the\nneuron devices consumes energy that can vary from of several pJ to a few fJ,\nwhich highlights the importance of the reset strategy in improving the energy\nefficiency of spintronic artificial spiking neurons.",
        "positive": "Insights on heterogeneity in blinking mechanisms and non-ergodicity\n  using sub-ensemble statistical analysis of single quantum-dots: Photo-luminescence intermittency (blinking) in semiconductor nanocrystals\n(NCs), a phenomenon ubiquitous to single-emitters, is generally considered to\nbe temporally random intensity fluctuations between bright (On) and dark (Off)\nstates. However, individual quantum-dots (QDs) rarely exhibit such telegraphic\nsignal, and yet, the vast majority of single-NC blinking data are analyzed\nusing a single fixed threshold, which generates binary trajectories. Further,\nblinking dynamics can vary dramatically over NCs in the ensemble, and it is\nunclear whether the exponents (m) of single-particle On-/Off-time distributions\n(P(t)-On/Off), which are used to validate mechanistic models of blinking, are\nnarrowly distributed or not. Here, we sub-classify an ensemble based on the\nemissivity of QDs, and subsequently compare the (sub)ensemble behaviors. To\nachieve this, we analyzed a large number (>1000) of intensity trajectories for\na model system, Mn+2 doped ZnCdS QDs, which exhibits diverse blinking dynamics.\nAn intensity histogram dependent thresholding method allowed us to construct\ndistributions of relevant blinking parameters (such as m). Interestingly, we\nfind that single QD P(t)-On/Off s follow either truncated power law or power\nlaw, and their relative proportion vary over sub-populations. Our results\nreveal a remarkable variation in m(On/Off) amongst as well as within\nsub-ensembles, which implies multiple blinking mechanisms being operational\namong various QDs. We further show that the m(On/Off) obtained via cumulative\nsingle-particle P(t)-On/Off is clearly distinct from the weighted mean value of\nall single-particle m(On/Off), an evidence for the lack of ergodicity. Thus,\ninvestigation and analyses of a large number of QDs, albeit for a limited\ntime-span of few decades, is crucial to characterize possible blinking\nmechanisms and heterogeneity therein"
    },
    {
        "anchor": "Magnetization generated by microwave-induced Rashba interaction: We show that a controllable dc magnetization is accumulated in a junction\ncomprising a quantum dot coupled to non-magnetic reservoirs if the junction is\nsubjected to a time-dependent spin-orbit interaction. The latter is induced by\nan ac electric field generated by microwave irradiation of the gated junction.\nThe magnetization is caused by inelastic spin-flip scattering of electrons that\ntunnel through the junction, and depends on the polarization of the electric\nfield: a circularly polarized field leads to the maximal effect, while there is\nno effect in a linearly polarized field. Furthermore, the magnetization\nincreases as a step function (smoothened by temperature) as the microwave\nphoton energy becomes larger than the absolute value of the difference between\nthe single energy level on the quantum dot and the common chemical potential in\nthe leads.",
        "positive": "Vector magnetic field microscopy using nitrogen vacancy centers in\n  diamond: The localized spin triplet ground state of a nitrogen vacancy (NV) center in\ndiamond can be used in atomic-scale detection of local magnetic fields. Here we\npresent a technique using these defects in diamond to image fields around\nmagnetic structures. We extract the local magnetic field vector by probing\nresonant transitions of the four fixed tetrahedral NV orientations. In\ncombination with confocal microscopy techniques, we construct a 2-dimensional\nimage of the local magnetic field vectors. Measurements are done in external\nfields less than 50 G and under ambient conditions."
    },
    {
        "anchor": "Energy relaxation in the spin-polarized disordered electron liquid: The energy relaxation in the spin-polarized disordered electron systems is\nstudied in the diffusive regime. We derived the quantum kinetic equation in\nwhich the kernel of electron-electron collision integral explicitly depends on\nthe electron magnetization. As the consequence, the inelastic scattering rate\nis found to have non-monotonic dependence on the spin polarization of the\nelectron system.",
        "positive": "Single-particle and Interaction Effects on the Cohesion and Transport\n  and Magnetic Properties of Metal Nanowires at Finite Voltages: The single-particle and interaction effects on the cohesion, electronic\ntransport, and some magnetic properties of metallic nanocylinders have been\nstudied at finite voltages by using a generalized mean-field electron model.\nThe electron-electron interactions are treated in the self-consistent Hartree\napproximation. Our results show the single-particle effect is dominant in the\ncohesive force, while the nonzero magnetoconductance and magnetotension\ncoefficients are attributed to the interaction effect. Both single-particle and\ninteraction effects are important to the differential conductance and magnetic\nsusceptibility."
    },
    {
        "anchor": "Probing Graphene's Nonlocality with Singular Metasurfaces: Singular graphene metasurfaces, conductivity gratings realized by\nperiodically suppressing the local doping level of a graphene sheet, have\nrecently been proposed to efficiently harvest THz light and couple it to\nsurface plasmons over broad absorption bands, achieving remarkably high field\nenhancement. However, the large momentum wavevectors thus attained are\nsensitive to the nonlocal behaviour of the underlying electron liquid. Here, we\nextend the theory of singular graphene metasurfaces to account for the full\nnonlocal optical response of graphene and discuss the resulting impact on the\nplasmon resonance spectrum. Finally, we propose a simple local analogue model\nthat is able to reproduce the effect of nonlocality in local-response\ncalculations by introducing a constant conductivity offset, which could prove a\nvaluable tool in the modelling of more complex experimental graphene-based\nplatforms.",
        "positive": "Excitonic effects in the optical properties of 2D materials: An equation\n  of motion approach: We present a unified description of the excitonic properties of four\nmonolayer transition-metal dichalcogenides (TMDC's) using an equation of motion\nmethod for deriving the Bethe-Salpeter equation in momentum space. Our method\nis able to cope with both continuous and tight-binding Hamiltonians, and is\nless computational demanding than the traditional first-principles approach. We\nshow that the role of the exchange energy is essential to obtain a good\ndescription of the binding energy of the excitons. The exchange energy at the\n$\\Gamma-$point is also essential to obtain the correct position of the\nC-exciton peak. Using our model we obtain a good agreement between the Rydberg\nseries measured for WS$_2$. We discuss how the absorption and the Rydberg\nseries depend on the doping. Choosing $r_0$ and the doping we obtain a good\nqualitative agreement between the experimental absorption and our calculations\nfor WS$_2$. We also derive a semi-analytical version of Ellitot's formula for\nTMDC's."
    },
    {
        "anchor": "AC Josephson effect in finite-length nanowire junctions with Majorana\n  modes: It has been predicted that superconducting junctions made with topological\nnanowires hosting Majorana bound states (MBS) exhibit an anomalous\n4\\pi-periodic Josephson effect. Finding an experimental setup with these\nunconventional properties poses, however, a serious challenge: for\nfinite-length wires, the equilibrium supercurrents are always 2\\pi-periodic as\nanticrossings of states with the same fermionic parity are possible. We show,\nhowever, that the anomaly survives in the transient regime of the ac Josephson\neffect. Transients are moreover protected against decay by quasiparticle\npoisoning as a consequence of the quantum Zeno effect, which fixes the parity\nof Majorana qubits. The resulting long-lived ac Josephson transients may be\neffectively used to detect MBS.",
        "positive": "Topological quantization and degeneracy in Josephson-junction arrays: We consider the conductivity quantization in two-dimensional arrays of\nmesoscopic Josephson junctions, and examine the associated degeneracy in\nvarious regimes of the system. The filling factor of the system may be\ncontrolled by the gate voltage as well as the magnetic field, and its\nappropriate values for quantization is obtained by employing the Jain hierarchy\nscheme both in the charge description and in the vortex description. The\nduality between the two descriptions then suggests the possibility that the\nsystem undergoes a change in degeneracy while the quantized conductivity\nremains fixed."
    },
    {
        "anchor": "Parametric generation of spin waves in nano-scaled magnonic conduits: The research feld of magnonics proposes a low-energy wave-logic computation\ntechnology based on spin waves to complement the established CMOS technology\nand provide a basis for emerging unconventional computation architectures.\nHowever, magnetic damping is a limiting factor for all-magnonic logic circuits\nand multi-device networks, ultimately rendering mechanisms to effciently\nmanipulate and amplify spin waves a necessity. In this regard, parallel pumping\nis a versatile tool since it allows to selectively generate and amplify spin\nwaves. While extensively studied in microscopic systems, nano-scaled systems\nare lacking investigation to assess the feasibility and potential future use of\nparallel pumping in magnonics. Here, we investigate a longitudinally magnetized\n100 nm-wide magnonic nano-conduit using space and time-resolved micro-focused\nBrillouin-light-scattering spectroscopy. Employing parallel pumping to generate\nspin waves, we observe that the non-resonant excitation of dipolar spin waves\nis favored over the resonant excitation of short wavelength exchange spin\nwaves. In addition, we utilize this technique to access the effective spin-wave\nrelaxation time of an individual nano-conduit, observing a large relaxation\ntime up to (115.0 +- 7.6) ns. Despite the significant decrease of the pumping\neffciency in the investigated nano-conduit, a reasonably small threshold is\nfound rendering parallel pumping feasible on the nano-scale.",
        "positive": "Kramers barrier crossing as a cooling machine: The achievement of local cooling is a prominent goal in the design of\nfunctional transport nanojunctions. One generic mechanism for local cooling is\ndriving a system through a local uphill potential step. In this paper we\nexamine the manifestation of this mechanism in the context of the Kramers\nbarrier crossing problem. For a particle crossing a barrier, the local\neffective temperature and the local energy exchange with the thermal\nenvironment are calculated, and the coefficient of performance of the ensuing\ncooling process is evaluated."
    },
    {
        "anchor": "Reconfigurable quantum logic gates using Rashba controlled spin\n  polarized currents: A reconfigurable logic gate is proposed in a two-dimensional double quantum\nwire system with a coupling window enabled by a Rashba field. Manipulating the\nspin states of incoming electrons several quantum logic gates (OR, AND, XOR,\nCNOT) can be implemented. The logic gate functionality can be switched by\ntuning the Rashba parameter only. In this context, we investigate suitable\nconfigurations of the device region by embedding a quantum point contact\nlocated in the coupling region to obtain all four logic gates. The ballistic\nspin polarized transmission functions are calculated using an effective mass\nscattering formalism in the framework of a multi-channel, multi-terminal\nsystem. Owing its versatility, the proposed logic gate can be integrated in\nprogrammable architectures, able to implement both classical and quantum\nalgorithms.",
        "positive": "Exact density-functional potentials for time-dependent quasiparticles: We calculate the exact Kohn-Sham potential that describes, within\ntime-dependent density-functional theory, the propagation of an electron\nquasiparticle wavepacket of non-zero crystal momentum added to a ground-state\nmodel semiconductor. The potential is observed to have a highly nonlocal\nfunctional dependence on the charge density, in both space and time, giving\nrise to features entirely lacking in local or adiabatic approximations. The\ndependence of the non-equilibrium part of the Kohn-Sham electric field on the\nlocal current and charge density is identified as a key element of the correct\nKohn-Sham functional."
    },
    {
        "anchor": "Many-body corrections to cyclotron resonance in monolayer and bilayer\n  graphene: Cyclotron resonance in graphene is studied with focus on many-body\ncorrections to the resonance energies, which evade Kohn's theorem. The genuine\nmany-body corrections turn out to derive from vacuum polarization, specific to\ngraphene, which diverges at short wavelengths. Special emphasis is placed on\nthe need for renormalization, which allows one to determine many-body\ncorrections uniquely from one resonance to another. For bilayer graphene, in\nparticular, both intralayer and interlayer coupling strengths undergo infinite\nrenormalization; as a result, the renormalized velocity and interlayer coupling\nstrength run with the magnetic field. A comparison of theory with the\nexperimental data is made for both monolayer and bilayer graphene.",
        "positive": "Atomic size oscillations in conductance histograms for gold nanowires\n  and the influence of work hardening: Nanowires of different nature have been shown to self-assemble as a function\nof stress at the contact between two macroscopic metallic leads. Here we\ndemonstrate for gold wires that the balance between various metastable nanowire\nconfigurations is influenced by the microstructure of the starting materials\nand we discover a new set of periodic structures, which we interpret as due to\nthe atomic discreteness of the contact size for the three principal crystal\norientations."
    },
    {
        "anchor": "Proposal for Electron Quantum Spin Talbot Effect: We propose a spin polarized Talbot effect for an electron beam scattered from\na grating of magnetic nanostructures. Existing periodic magnetic nanostructures\ncan be used in conjunction with electron-beam illumination to create a spin\npolarized replica of the transversely periodic exit surface beam a Talbot\nlength away. Experiments have been proposed to verify the effect in a two\ndimensional electron gas and an atomically flat surface by spin polarized\nscanning probe microscopy. This effect provides a new route to modulate\nelectron spin distributions in two dimensional space.",
        "positive": "Characterising submonolayer deposition via visibility graphs: We use visibility graphs as a tool to analyse the results of kinetic Monte\nCarlo (kMC) simulations of submonolayer deposition in a one-dimensional point\nisland model. We introduce an efficient algorithm for the computation of the\nvisibility graph resulting from a kMC simulation and show that from the\nproperties of the visibility graph one can determine the critical island size,\nthus demonstrating that the visibility graph approach, which implicitly\ncombines size and spatial data, can provide insights into island nucleation and\ngrowth processes."
    },
    {
        "anchor": "Enhancement of the Curie temperature in small particles of weak\n  itinerant ferromagnets: Self consistent renormalization theory of itinerant ferromagnets is used to\ncalculate the Curie temperature of clusters down to approximately 100 atoms in\nsize. In these clusters the electrons responsible for the magnetic properties\nare assumed to be (weakly) itinerant. It is shown that the Curie temperature\ncan be larger than in the bulk. The effect originates from the phenomenon of\nlevel repulsion in chaotic quantum systems, which suppresses spin fluctuations.\nSince the latter destroy the magnetic order the resulting Curie temperature\nincreases, contrary to expectations of the naive Stoner picture. The\ncalculations are done assuming that the energy levels of the cluster are\ndescribed by the Gaussian Orthogonal Ensemble of random matrix theory.",
        "positive": "Comment on ``Fundamental relation between electrical and thermoelectric\n  transport coefficients in the quantum Hall regime'': Paper withdrawn due to errors. Revised version may or may not appear in the\nfuture."
    },
    {
        "anchor": "Proposed ultra wide-band tunable THz RT lasers based on momentum space\n  negative conductivity under electron streaming in hNB-graphene sandwiches: Observations of terahertz loss to gain switching in transmission through\ngates on biased graphene sandwiches are explained by response under electron\nstreaming in graphene. Basing on this consideration the terahertz source is\nproposed consisting of silicon resonator placed on the sandwich with current\nflow in graphene. It should provide tunable by bias emission in wide terahertz\nband. The source is direct terahertz analog of tunable microwave laser\ndemonstrated.",
        "positive": "Surface Ferron Excitations in Ferroelectrics and Their Directional\n  Routing: The duality between the electric and magnetic dipoles inspires recent\ncomparisons between ferronics and magnonics. Here we predict surface\npolarization waves or ``ferrons\" in ferroelectric insulators, taking the\nlong-range dipolar interaction into account. We predict properties that are\nstrikingly different from the magnetic counterpart, \\textit{i.e.} the surface\n``Damon-Eshbach\" magnons in ferromagnets. The dipolar interaction pushes the\nferron branch with locked circular polarization and momentum to the ionic\nplasma frequency. The low-frequency modes are on the other hand in-plane\npolarized normal to their wave vectors. The strong anisotropy of the lower\nbranch renders directional emissions of electric polarization and chiral near\nfields when activated by a focused laser beam, allowing optical routing in\nferroelectric devices."
    },
    {
        "anchor": "Low-energy properties of fractional helical Luttinger liquids: We investigate the low-energy properties of (quasi) helical and fractional\nhelical Luttinger liquids. In particular, we calculate the Drude peak of the\noptical conductivity, the density of states, as well as charge transport\nproperties of the interacting system with and without attached Fermi liquid\nleads at small and large (compared to the gap) frequencies. For fractional\nwires, we find that the low energy tunneling density of states vanishes. The\nconductance of a fractional helical Luttinger liquid is non-integer. It is\nindependent of the Luttinger parameters in the wire, despite the intricate\nmixing of charge and spin degrees of freedom, and only depends on the relative\nlocking of charge and spin degrees of freedom.",
        "positive": "Gate-tunable, normally-on to normally-off memristance transition in\n  patterned LaAlO3/SrTiO3 interfaces: We report gate-tunable memristive switching in patterned LaAlO3/SrTiO3\ninterfaces at cryogenic temperatures. The application of voltages in the order\nof a few volts to the back gate of the device allows controlling and\nswitching-on and -off the inherent memory functionality (memristance). For\nlarge and small gate voltages a simple non-linear resistance characteristic is\nobserved while a pinched hysteresis loop and memristive switching occurs in an\nintermediate voltage range. The memristance is further controlled by the\ndensity of oxygen vacancies, which is tuned by annealing the sample at 300\n{\\deg}C in nitrogen atmosphere. Depending on the annealing time the memristance\nat zero gate voltage can be switched on and off leading to normally-on and\nnormally-off memristors. The presented device offers reversible and\nirreversible control of memristive characteristics by gate voltages and\nannealing, respectively, which may allow to compensate fabrication\nvariabilities of memristors that complicate the realization of large\nmemristor-based neural networks."
    },
    {
        "anchor": "Non-linear Transport Phenomena and Current-induced Hydrodynamics in\n  Ultra-high Mobility Two-dimensional Electron Gas: We report on non-linear transport phenomena at high filling factor and DC\ncurrent-induced electronic hydrodynamics in an ultra-high mobility (mu=20x10^6\ncm^2/Vs) two-dimensional electron gas in a narrow (15 micron wide) GaAs/AlGaAs\nHall bar for DC current densities reaching 0.67 A/m. The various phenomena and\nthe boundaries between the phenomena are captured together in a two-dimensional\ndifferential resistivity map as a function of magnetic field (up to 250 mT) and\nDC current. This map, which resembles a phase diagram, demarcate distinct\nregions dominated by Shubnikov-de Haas (SdH) oscillations (and phase inversion\nof these oscillations) around zero DC current; negative magnetoresistance and a\ndouble-peak feature (both ballistic in origin) around zero field; and Hall\nfield-induced resistance oscillations (HIROs) radiating out from the origin.\nFrom a detailed analysis of the data near zero field, we show that increasing\nthe DC current suppresses the electron-electron scattering length that drives a\ngrowing hydrodynamic contribution to both the differential longitudinal and\ntransverse (Hall) resistivities. Our approach to induce hydrodynamics with DC\ncurrent differs from the more usual approach of changing the temperature. We\nalso find a significant (factor of two to four) difference between the quantum\nlifetime extracted from SdH oscillations, and the quantum lifetime extracted\nfrom HIROs. In addition to observing HIRO peaks up to the seventh order, we\nobserve an unexpected HIRO-like feature close to mid-way between the\nfirst-order and the second-order HIRO maxima at high DC current.",
        "positive": "Ballistic and shift currents in the bulk photovoltaic effect theory: The bulk photovoltaic effect (BPVE) -- generation of electric currents by\nlight in noncentrosymmetric materials in the absence of electric fields and\ngradients -- has been intensively investigated in the end of the last century.\nThe outcomes including all main aspects of this phenomenon were summarized in\nreview and books. A new upsurge of interest to the BPVE occurred recently and\nresulted in a flux of misleading theoretical and experimental publications\ncentered around the so-called shift current. Numerous top-rated recent\npublications ignore the basic principles of charge-transport phenomena and the\nprevious results of joined experimental-theoretical studies. Specifically,\ndominating (or substantial) contributions to the currents caused by asymmetry\nof the momentum distributions of electrons and holes are missed. The widespread\nstarting relation for the shift current, originating from the quadratic\nnonlinear response theory and pretending to be omnipotent, is in fact\nincomplete. It ignores kinetic processes of relaxation and recombination of\nphoto-excited electrons and leads to non-vanishing shift currents in thermal\nequilibrium. The goals of this methodical note is to specify and argue the\nbenchmarks of the BPVE theory and return the studies on the right track in the\ninterest of development of photovoltaic devices."
    },
    {
        "anchor": "Spectroscopy of snake states using a graphene Hall bar: An approach to observe snake states in a graphene Hall bar containing a\npn-junction is proposed. The magnetic field dependence of the bend resistance\nin a ballistic graphene Hall bar structure containing a tilted pn-junction\noscillates as a function of applied magnetic field. We show that each\noscillation is due to a specific snake state that moves along the pn-interface.\nFurthermore depending on the value of the magnetic field and applied potential\nwe can control the lead in which the electrons will end up and hence control\nthe response of the system.",
        "positive": "Semiempirical pseudopotential approach for nitride-based nanostructures\n  and {\\it ab initio} based passivation of free surfaces: We present a semiempirical pseudopotential method based on screened atomic\npseudopotentials and derived from \\textit{ab initio} calculations. This\napproach is motivated by the demand for pseudopotentials able to address\nnanostructures, where \\textit{ab initio} methods are both too costly and\ninsufficiently accurate at the level of the local-density approximation, while\nmesoscopic effective-mass approaches are inapplicable due to the small size of\nthe structures along, at least, one dimension. In this work we improve the\ntraditional pseudopotential method by a two-step process: First, we invert a\nset of self-consistently determined screened {\\it ab initio} potentials in\nwurtzite GaN for a range of unit cell volumes, thus determining\nspherically-symmetric and structurally averaged atomic potentials. Second, we\nadjust the potentials to reproduce observed excitation energies. We find that\nthe adjustment represents a reasonably small perturbation over the potential,\nso that the ensuing potential still reproduces the original wave functions,\nwhile the excitation energies are significantly improved. We furthermore deal\nwith the passivation of the dangling bonds of free surfaces which is relevant\nfor the study of nanowires and colloidal nanoparticles. We present a\nmethodology to derive passivant pseudopotentials from {\\it ab initio}\ncalculations. We apply our pseudopotential approach to the exploration of the\nconfinement effects on the electronic structure of GaN nanowires."
    },
    {
        "anchor": "Zero-energy Andreev bound states in iron-based superconductor Fe(Te,Se): Majorana bound states have been predicted to exist in vortices of topological\nsuperconductors (SC). A realization of the Fu-Kane model, based on a\nthree-dimensional topological insulator brought into proximity to an $s$-wave\nSC, in iron-based SC Fe(Te,Se) has attracted strong interest after pronounced\nzero-energy bias peaks were observed in several experiments. Here, we show\nthat, by taking into account inhomogeneities of the chemical potential or the\npresence of potential impurities on the surface of Fe(Te,Se), the emergence of\nthese zero-energy bias peaks can be explained by trivial Andreev bound states\n(ABSs) whose energies are close to zero. Our numerical simulations reveal that\nthe ABSs behave similarly to Majorana bound states. ABSs are localized only on\nthe, say, top surface and cannot be distinguished from their topological\ncounterparts in transport experiments performed with STM tips. Thus, such ABSs\ndeserve a careful investigation of their own.",
        "positive": "Ultra-dense phosphorus in germanium delta-doped layers: Phosphorus (P) in germanium (Ge) delta-doped layers are fabricated in\nultra-high vacuum by adsorption of phosphine molecules onto an atomically flat\nclean Ge(001) surface followed by thermal incorporation of P into the lattice\nand epitaxial Ge overgrowth by molecular beam epitaxy. Structural and\nelectrical characterizations show that P atoms are confined, with minimal\ndiffusion, into an ultra-narrow 2-nm-wide layer with an electrically-active\nsheet carrier concentration of 4x10^13 cm-2 at 4.2 K. These results open up the\npossibility of ultra-narrow source/drain regions with unprecedented carrier\ndensities for Ge n-channel field effect transistors."
    },
    {
        "anchor": "Resonant optical electron transfer in one-dimensional multiwell\n  structures: We consider coherent single-electron dynamics in the one-dimensional\nnanostructure under resonant electromagnetic pulse. The structure is composed\nof two deep quantum wells positioned at the edges of structure and separated by\na sequence of shallow internal wells. We show that complete electron transfer\nbetween the states localized in the edge wells through one of excited\ndelocalized states can take place at discrete set of times provided that the\npulse frequency matches one of resonant transition frequencies. The transfer\ntime varies from several tens to several hundreds of picoseconds and depends on\nthe structure and pulse parameters. The results obtained in this paper can be\napplied to the developments of the quantum networks used in quantum\ncommunications and/or quantum information processing.",
        "positive": "Radiative properties of multi-carrier bound excitons in GaAs: Excitons in semiconductors can have multiple lifetimes due to spin dependent\noscillator strengths and interference between different recombination pathways.\nIn addition, strain and symmetry effects can further modify lifetimes via the\nremoval of degeneracies. We present a convenient formalism for predicting the\noptical properties of ${k=0}$ excitons with an arbitrary number of charge\ncarriers in different symmetry environments. Using this formalism, we predict\nthree distinct lifetimes for the neutral acceptor bound exciton in GaAs, and\nconfirm this prediction through polarization dependent and time-resolved\nphotoluminescence experiments. We find the acceptor bound-exciton lifetimes to\nbe ${T_o (1,3,3/4)}$ where ${T_o = (0.61 \\pm 0.12) \\text{ns}}$. Furthermore, we\nprovide an estimate of the intra-level and inter-level exciton spin-relaxation\nrates."
    },
    {
        "anchor": "Controllable Spin-Charge Transport in Strained Graphene Nanoribbon\n  Devices: We theoretically investigate the spin-charge transport in two-terminal device\nof graphene nanoribbons in the presence of an uniform uniaxial strain,\nspin-orbit coupling, exchange field and smooth staggered potential. We show\nthat the direction of applied strain can efficiently tune strain-strength\ninduced oscillation of band-gap of armchair graphene nanoribbon (AGNR). It is\nalso found that electronic conductance in both AGNR and zigzag graphene\nnanoribbons (ZGNRs) oscillates with Rashba spin-orbit coupling akin to the\nDatta-Das field effect transistor. Two distinct strain response regimes of\nelectronic conductance as function of spin-orbit couplings (SOC) magnitude are\nfound. In the regime of small strain, conductance of ZGNR presents stronger\nstrain dependence along the longitudinal direction of strain. Whereas for high\nvalues of strain shows larger effect for the transversal direction.\nFurthermore, the local density of states (LDOS) shows that depending on the\nsmoothness of the staggered potential, the edge state of AGNR can either emerge\nor be suppressed. These emerging states can be determined experimentally by\nperforming spatially scanning tunneling microscope or by scanning tunneling\nspectroscopy. Our findings open up new paradigms of manipulation and control of\nstrained graphene based nanostructure for application on novel topological\nquantum devices.",
        "positive": "Surprisingly large anomalous Hall effect and giant negative\n  magnetoresistance in half-topological semimetals: Large intrinsic anomalous Hall effect (AHE) due to the Berry curvature in\nmagnetic topological semimetals is attracting enormous interest due to its\nfundamental importance and technological relevance. Mechanisms resulting in\nlarge intrinsic AHE include diverging Berry curvature in Weyl semimetals,\nanticrossing nodal rings or points of non-trivial bands, and noncollinear spin\nstructures. Here we show that a half-topological semimetal (HTS) state near a\ntopological critical point can provide a new mechanism for driving an\nexceptionally large AHE. We reveal this through a systematic experimental and\ntheoretical study of the antiferromagnetic (AFM) half-Heusler compound TbPdBi.\nWe not only observed an unusual AHE with a surprisingly large anomalous Hall\nangle {\\Theta}H (tan {\\Theta}H ~ 2, the largest among the antiferromagnets) in\nits field-driven ferromagnetic (FM) phase, but also found a distinct Hall\nresistivity peak in the canted AFM phase within a low field range, where its\nisothermal magnetization is nearly linearly dependent on the field. Moreover,\nwe observed a nearly isotropic, giant negative magnetoresistance with a\nmagnitude of ~98%. Our in-depth theoretical modelling demonstrates that these\nexotic transport properties originate from the HTS state. A minimal Berry\ncurvature cancellation between the trivial spin-up and nontrivial spin-down\nbands results not only in an extremely large AHE, but it also enhances the spin\npolarization of the spin-down bands substantially and thus leads to a giant\nnegative magnetoresistance. Our study advances the understanding of the\ninterplay between band topology and magnetism and offers new clues for\nmaterials design for spintronics and other applications."
    },
    {
        "anchor": "Helitronics for classical and unconventional computing: Magnetic textures are promising candidates for unconventional computing due\nto their non-linear dynamics. We propose to investigate the rich variety of\nseemingly trivial lamellar magnetic phases, e.g., helical, spiral, stripy\nphase, or other one-dimensional soliton lattices. These are the natural stray\nfield-free ground states of almost every magnet. The order parameters of these\nphases may be of potential interest for both classical and unconventional\ncomputing, which we refer to as helitronics. For the particular case of a\nchiral magnet and its helical phase, we use micromagnetic simulations to\ndemonstrate the working principles of all-electrical (i) classical binary\nmemory cells and (ii) memristor and neuron cells, based on the orientation of\nthe helical stripes.",
        "positive": "N- and p-type carrier injections into WSe2 with van der Waals contacts\n  of two-dimensional materials: We demonstrated n-type and p-type carrier injections into a transition metal\ndichalcogenide (TMD) WSe2 using van der Waals (vdW) contacts of two-dimensional\n(2D) materials: graphite for an n-type contact and NbSe2 for a p-type contact.\nInstead of conventional methods such as the evaporation of metals on TMD, 2D\nmetals were transferred onto WSe2 in order to form van der Waals contacts. With\nthese contacts, we demonstrated a small Schottky barrier height for both\ncarrier polarities. Our finding reveals the potential of a high-performance vdW\nmetal/semiconductor contact for use in electronics applications."
    },
    {
        "anchor": "Hyperfine-induced dephasing in three-electron spin qubits: We calculate the pure dephasing time of three-electron exchange-only qubits\ndue to interaction with the nuclear hyperfine field. Within the $S=S_z=1/2$\nspin subspace, we derive formulas for the dephasing time in the $(1,1,1)$\ncharge region and in the neighboring charge sectors coupled by tunneling. The\nnuclear field and the tunneling are taken into account in a second order\napproximation. The analytical solutions accurately reproduce the numerical\nevaluation of the full problem, and in comparison with existing experimental\ndata, we find that the dephasing times are longer but on the same timescale as\nfor single spins. Our analysis also applies to the resonant exchange (RX),\nalways-on exchange-only (AEON) and hybrid qubits.",
        "positive": "Thermal antenna behavior for thin films structures: We show that under proper conditions thin films structures behave like\nthermal sources that are able to emit radiation in well defined directions over\na broad spectral band for both polarization states of light. This effect\nresults from the quantization of modes inside the structure as in a Fabry-Perot\nresonator. A theoretical demonstration of this effect is given using the matrix\ntransfer method. This result is similar to the best efficient reported results\nwith gratings but using a completely different physical principle [J. J.\nGreffet et al., Nature 416, 61 (2002)]."
    },
    {
        "anchor": "Microscopic Origin of Charged Impurity Scattering and Flicker Noise in\n  MoS2 field-effect Transistors: Scattering of charge carriers and flicker noise in electrical transport are\nthe central performance limiting factors in electronic devices, but their\nmicroscopic origin in molybdenum disulphide~(MoS$_2$)-based field effect\ntransistors remains poorly understood. Here, we show that both carrier\nscattering and low-frequency $1/f$ noise in mechanically exfoliated ultra-thin\nMoS$_2$ layers are determined by the localized trap states located within the\nMoS$_2$ channel itself. The trap states not only act as Coulomb scattering\ncenters that determine transport in both equilibrium ($eV< k_BT$) and\nnon-equilibrium ($eV>k_BT$) regimes, where $V$ and $T$ are the source drain\nbias and temperature respectively, but also exchange carriers with the channel\nto produce the conductivity noise. The internal origin of the trap states was\nfurther confirmed by studying noise in MoS$_2$ films deposited on crystalline\nboron nitride substrates. Possible origin and nature of the trap states is also\ndiscussed.",
        "positive": "Magneto-transport Subbands Spectroscopy in InAs Nanowires: We report on magneto-transport measurements in InAs nanowires under large\nmagnetic field (up to 55T), providing a direct spectroscopy of the 1D\nelectronic band structure. Large modulations of the magneto-conductance\nmediated by an accurate control of the Fermi energy reveal the Landau\nfragmentation, carrying the fingerprints of the confined InAs material. Our\nnumerical simulations of the magnetic band structure consistently support the\nexperimental results and reveal key parameters of the electronic confinement."
    },
    {
        "anchor": "Polaritonic quantisation in nonlocal polar material: In the Reststrahlen region, between the transverse and longitudinal phonon\nfrequencies, polar dielectric materials respond metallically to light and the\nresulting strong light-matter interactions can lead to the formation of hybrid\nquasiparticles termed surface phonon polaritons. Recent works have demonstrated\nthat when an optical system contains nanoscale polar elements these excitations\ncan acquire a longitudinal field component as a result of the material\ndispersion of the lattice, leading to the formation of secondary quasiparticles\ntermed longitudinal-transverse polaritons. In this work we build on previous\nmacroscopic electromagnetic theories developing a full second-quantised theory\nof longitudinal-transverse polaritons. Beginning from the Hamiltonian of the\nlight-matter system we treat distortion to the lattice introducing an elastic\nfree energy. We then diagonalise the Hamiltonian, demonstrating the equations\nof motion for the polariton are equivalent to the those of macroscopic\nelectromagnetism and quantise the nonlocal operators. Finally we demonstrate\nhow to reconstruct the electromagnetic fields in terms of the polariton states\nand explore polariton induced enhancements of the Purcell factor. These results\ndemonstrate how nonlocality can narrow, enhance and spectrally tune near field\nemission with applications in mid-infrared sensing.",
        "positive": "Line of Dirac Nodes in Hyper-Honeycomb Lattices: We propose a family of free fermion lattice models that have \"Dirac loops\",\nclosed lines of Dirac nodes in momentum space, on which the density of states\nvanishes linearly with energy. Those lattices all possess the planar trigonal\nconnectivity present in graphene, but are three dimensional. We show that their\nhighly anisotropic and multiply-connected Fermi surface leads to quantized Hall\nconductivities in three dimensions for magnetic fields with toroidal geometry.\nIn the presence of spin-orbit coupling, we show that those structures have\ntopological surface states. We discuss the feasibility of realizing the\nstructures as new allotropes of carbon."
    },
    {
        "anchor": "Shape-induced anisotropy in antiferromagnetic nanoparticles: High fraction of the surface atoms considerably enhances the influence of\nsize and shape on the magnetic and electronic properties of nanoparticles.\nShape effects in ferromagnetic nanoparticles are well understood and allow to\nset and control the parameters of a sample that affect its magnetic anisotropy\nduring production. In the present paper we study the shape effects in the other\nwidely used magnetic materials -- antiferromagnets, -- which possess\nvanishingly small or zero macroscopic magnetization. We take into account the\ndifference between the surface and bulk magnetic anisotropy of a nanoparticle\nand show that the effective magnetic anisotropy depends on the particle shape\nand crystallographic orientation of its faces. Corresponding shape-induced\ncontribution to the magnetic anisotropy energy is proportional to the particle\nvolume, depends on magnetostriction, and can cause formation of equilibrium\ndomain structure. Crystallographic orientation of the nanoparticle surface\ndetermines the type of domain structure. The proposed model allows to predict\nthe magnetic properties of antiferromagnetic nanoparticles depending on their\nshape and treatment.",
        "positive": "Mapping of H\u00fcckel Zigzag Carbon Nanotubes onto independent Polyene\n  chains: application to periodic Nanotubes: The electric polarizability and the spread of the total position tensors are\nused to characterize the metallic vs insulator nature of large (finite)\nsystems. Finite clusters are usually treated within the open boundary condition\nformalism. This introduces border effects, which prevents a fast convergence to\nthe thermodynamic limit and which can be eliminated within the formalism of\nperiodic boundary conditions. Recently, we have introduced an original approach\nto periodic boundary conditions, named Clifford Boundary Conditions. It\nconsiders a finite fragment extracted from a periodic system and the\nmodification of its topology into that of a Clifford Torus. The quantity\nrepresenting the position is modified in order to fulfill the system\nperiodicity. In this work, we apply the formalism of Clifford Boundary\nConditions to the case of Carbon Nanotubes, whose treatment results to be\nparticularly simple for the Zigzag geometry. Indeed, we demonstrate that at the\nH\\\"uckel level these nanotubes, either finite or periodic, are formally\nequivalent to a collection of {\\em non-interacting dimerized linear chains},\nthus simplifying their treatment. This equivalence is used to describe some\nnanotube properties as the sum of the contributions of the independent chains\nand to identify the origin of peculiar behaviors (such as the conductivity).\nIndeed, if the number of hexagons along the circumference is a multiple of\nthree a metallic behavior is found, namely a divergence of both the (per\nelectron) polarizability and total position spread of at least one linear\nchain. These results are in agreement with those in the literature from\nTight-Binding calculations."
    },
    {
        "anchor": "Vortex-antivortex pairs induced by curvature in toroidal nanomagnets: We show that the curvature of nanomagnets can be used to induce chiral\ntextures in the magnetization field. Among the phenomena related to the\ninterplay between geometry and magnetic behavior at nanomagnets, an effective\ncurvature-induced chiral interaction has been recently predicted. In this work,\nit is shown that a magnetization configuration consisting of two structures\nwith opposite winding numbers (vortex and antivortex) appear as remanent states\nin hollow toroidal nanomagnets. It is shown that these topological\nconfigurations are a result of a chiral interaction induced by curvature. In\nthis way, the obtained results present a new form to produce stable vortices\nand antivortices by using nanomagnets with variable curvature.",
        "positive": "Classical Nuclear Motion in Quantum Transport: An ab initio quantum-classical mixed scheme for the time evolution of\nelectrode-device-electrode systems is introduced to study nuclear dynamics in\nquantum transport. Two model systems are discussed to illustrate the method.\nOur results provide the first example of current-induced molecular desorption\nas obtained from a full time-dependent approach and suggest the use of ac\nbiases as a way to tailor electromigration. They also show the importance of\nnon-adiabatic effects for ultrafast phenomena in nanodevices."
    },
    {
        "anchor": "Perfect crossed Andreev reflection in Dirac hybrid junctions in the\n  quantum Hall regime: Perfect crossed Andreev reflection (CAR) is striking for high-efficiency\nCooper pair splitting which bears promising applications in quantum\ncommunication. Recent experimental advances have disclosed the way to explore\nCAR in Dirac fermion systems under ultra-strong magnetic fields. We develop a\nscattering approach to study quantum Hall-superconductor-quantum Hall (QH-S-QH)\njunctions formed by a two-dimensional (2D) time-reversal symmetric Dirac\nsemimetal. We propose two different setups of the hybrid junction in the\nquantum limit where only zeroth Landau levels are involved in transport to\nexploit perfect CAR. In both setups, the CAR probability can reach unity\nwithout applying bias voltage and is controllable by the magnetic field\nstrength, junction width, length and doping of the superconductor. CAR\ndominates the nonlocal transport and is directly measurable by the differential\nconductances. We also identify a quantized spin injection per CAR event in one\nof the two setups. Our proposal is experimentally feasible and will be helpful\nfor exploring high-efficiency Cooper pair splitting and spin injection in Dirac\nmaterials.",
        "positive": "Recent advances in hole-spin qubits: In recent years, hole-spin qubits based on semiconductor quantum dots have\nadvanced at a rapid pace. We first review the main potential advantages of\nthese hole-spin qubits with respect to their electron-spin counterparts, and\ngive a general theoretical framework describing them. The basic features of\nspin-orbit coupling and hyperfine interaction in the valence band are\ndiscussed, together with consequences on coherence and spin manipulation. In\nthe second part of the article we provide a survey of experimental\nrealizations, which spans a relatively broad spectrum of devices based on GaAs,\nSi, or Si/Ge heterostructures. We conclude with a brief outlook."
    },
    {
        "anchor": "Twist- and gate-tunable proximity spin-orbit coupling, spin relaxation\n  anisotropy, and charge-to-spin conversion in heterostructures of graphene and\n  transition-metal dichalcogenides: We present a DFT-based investigation of the twist-angle dependent proximity\nspin-orbit coupling (SOC) in graphene/TMDC structures. We find that for\nMo-based TMDCs the proximity valley-Zeeman SOC exhibits a maximum at around\n15--20{\\deg}, and vanishes at 30{\\deg}, while for W-based TMDCs we find an\nalmost linear decrease of proximity valley-Zeeman SOC when twisting from\n0{\\deg} to 30{\\deg}. The induced Rashba SOC is rather insensitive to twisting,\nwhile acquiring a nonzero Rashba phase angle, $\\varphi \\in [-20;40]${\\deg}, for\ntwist angles different from 0{\\deg} and 30{\\deg}. This finding contradicts\nearlier tight-binding predictions that the Rashba angle can be 90{\\deg} in the\nstudied systems. In addition, we study the influence of several tunability\nknobs on the proximity SOC for selected twist angles. By applying a transverse\nelectric field in the limits of $\\pm 2$ V/nm, mainly the Rashba SOC can be\ntuned by about 50\\%. The interlayer distance provides a giant tunability, since\nthe proximity SOC can be increased by a factor of 2--3, when reducing the\ndistance by about 10\\%. Encapsulating graphene between two TMDCs, both twist\nangles are important to control the interference of the individual proximity\nSOCs, allowing to precisely tailor the valley-Zeeman SOC in graphene, while the\nRashba SOC becomes suppressed. Finally, based on our effective Hamiltonians\nwith fitted parameters, we calculate experimentally measurable quantities such\nas spin lifetime anisotropy and charge-to-spin conversion efficiencies. The\nspin lifetime anisotropy can become giant, up to $10^4$, in encapsulated\nstructures. The charge-to-spin conversion, which is due to spin-Hall and\nRashba-Edelstein effects, can lead to twist-tunable non-equilibrium\nspin-density polarizations that are perpendicular and parallel to the applied\ncharge current.",
        "positive": "Thermalisation by a boson bath in a pure state: We consider a quantum system weakly coupled to a large heat bath of harmonic\noscillators. It is well known that such a boson bath initially at thermal\nequilibrium thermalises the system. We show that assuming a priori an\nequilibrium state is not necessary to obtain the thermalisation of the system.\nWe determine the complete Schr\\\"odinger time evolution of the subsystem of\ninterest for an initial pure product state of the composite system consisting\nof the considered system and the bath. We find that the system relaxes into\ncanonical equilibrium for almost all initial pure bath states of\nmacroscopically well-defined energy. The temperature of the system asymptotic\nthermal state is determined by the energy of the initial bath state as the\ncorresponding microcanonical temperature. Moreover, the time evolution of the\nsystem is identical to the one obtained assuming that the boson bath is\ninitially at thermal equilibrium with this temperature. A significant part of\nour approach is applicable to other baths and we identify the bath features\nwhich are requisite for the thermalisation studied."
    },
    {
        "anchor": "Dynamically controllable graphene three-port circulator: A new type of the graphene-based three-port circulator is suggested and\nanalysed. The cross-section of the component presents a three-layer structure\nconsisting of a layer of silicon, of silica and of graphene. In-plane figure\nresembles a common microwave nanostrip circulator with a circular graphene\nresonator and three waveguides symmetrically connected to it. The graphene is\nmagnetized normally to its plane by a DC magnetic field. The numerical\nsimulation demonstrates the isolation of -15 dB and insertion losses of -2 dB\nin 6.98 \\% frequency band with the central frequency 8.23THz.",
        "positive": "Ultrafast Depopulation of a Quantum Dot by LA-phonon-assisted Stimulated\n  Emission: We demonstrate ultrafast incoherent depopulation of a quantum dot from above\nto below the transparency point using LA-phonon-assisted emission stimulated by\na redshifted laser pulse. The QD is turned from a weakly vibronic system into a\nstrongly vibronic one by laser driving which enables the phonon-assisted\nrelaxation between the excitonic components of two dressed states. The\ndepopulation is achieved within a laser pulse-width-limited time of 20 ps and\nexhibits a broad tuning range of a few meV. Our experimental results are well\nreproduced by path-integral calculations."
    },
    {
        "anchor": "In situ observation of stress relaxation in epitaxial graphene: Upon cooling, branched line defects develop in epitaxial graphene grown at\nhigh temperature on Pt(111) and Ir(111). Using atomically resolved scanning\ntunneling microscopy we demonstrate that these defects are wrinkles in the\ngraphene layer, i.e. stripes of partially delaminated graphene. With low energy\nelectron microscopy (LEEM) we investigate the wrinkling phenomenon in situ.\nUpon temperature cycling we observe hysteresis in the appearance and\ndisappearance of the wrinkles. Simultaneously with wrinkle formation a change\nin bright field imaging intensity of adjacent areas and a shift in the moire\nspot positions for micro diffraction of such areas takes place. The stress\nrelieved by wrinkle formation results from the mismatch in thermal expansion\ncoefficients of graphene and the substrate. A simple one-dimensional model\ntaking into account the energies related to strain, delamination and bending of\ngraphene is in qualitative agreement with our observations.",
        "positive": "The importance of the interface for picosecond spin pumping in\n  antiferromagnet-heavy metal heterostructures: Interfaces between heavy metals (HMs) and antiferromagnetic insulators (AFIs)\nhave recently become highly investigated and debated systems in the effort to\ncreate spintronic devices able to function at terahertz frequencies. Such\nheterostructures have great technological potential because AFIs can generate\nsub-picosecond spin currents which the HMs can convert into charge signals. In\nthis work we demonstrate an optically induced picosecond spin transfer at the\ninterface between AFIs and Pt using time-resolved THz emission spectroscopy. We\nselect two antiferromagnets in the same family of fluoride cubic perovskites,\nKCoF3 and KNiF3, whose magnon frequencies at the centre of the Brillouin zone\ndiffer by an order of magnitude. By studying their behaviour with temperature\nwe correlate changes in the spin transfer efficiency across the interface to\nthe opening of a gap in the magnon density of states below the N\\'eel\ntemperature. Our observations are reproduced in a model based on the spin\nexchange between the localized electrons in the antiferromagnet and the free\nelectrons in Pt. These results constitute an important step in the rigorous\ninvestigation and understanding of the physics of AFIs/HMs interfaces on the\nultrafast timescale."
    },
    {
        "anchor": "Tuning inter-dot tunnel coupling of an etched graphene double quantum\n  dot by adjacent metal gates: Graphene double quantum open the possibility to use charge or spin degrees of\nfreedom for storing and manipulating quantum information in this new electronic\nmaterial. However, impurities and edge disorders in etched graphene\nnano-structures hinder the ability to control the inter-dot tunnel coupling,\ntc,the most important property of the artificial molecule. Here we report\nmeasurements of tc in an all-metal-gates-tuned graphene DQD. We find that tc\ncan be controlled continuously about a factor of four by employing a single\ngate. Furthermore, tc, can be changed monotonically about another factor of\nfour as electrons are gate-pumped into the dot one by one. The results suggest\nthat the strength of tunnel coupling in etched DQDs can be varied in a rather\nbroad range and in a controllable manner, which improves the outlook to use\ngraphene as a base material for qubit applications.",
        "positive": "Elementary excitations of single-photon emitters in hexagonal Boron\n  Nitride: Single-photon emitters serve as building blocks for many emerging concepts in\nquantum photonics. The recent identification of bright, tunable, and stable\nemitters in hexagonal boron nitride (hBN) has opened the door to quantum\nplatforms operating across the infrared to ultraviolet spectrum. While it is\nwidely acknowledged that defects are responsible for single-photon emitters in\nhBN, crucial details regarding their origin, electronic levels, and orbital\ninvolvement remain unknown. Here, we employ a combination of resonant inelastic\nX-ray scattering and photoluminescence spectroscopy in defective hBN unveiling\nan elementary excitation at 285 meV that gives rise to a plethora of harmonics\ncorrelated with single-photon emitters. We discuss the importance of N $\\pi^*$\nantibonding orbitals in shaping the electronic states of the emitters. The\ndiscovery of the elementary excitations of hBN provides new fundamental\ninsights into quantum emission in low-dimensional materials, paving the way for\nfuture investigations in other platforms."
    },
    {
        "anchor": "Probing mirror anomaly and classes of Dirac semimetals with circular\n  dichroism: We theoretically investigate the optical activity of three dimensional Dirac\nsemimetals (DSMs) using circular dichroism (CD). We show that DSMs in the\npresence of a magnetic field in any one of the mirror-symmetric planes of the\nmaterials exhibit a notable dichroic behavior. In particular, for different\norientations of the light field with respect to the mirror-symmetric plane, the\nCD in type-II DSMs can detect the presence of mirror anomaly by showing sharply\ndistinct patterns at the mirror-symmetric angle. Interestingly, CD can also\ndistinguish type-II DSMs having only one Dirac point at a time-reversal\ninvariant momentum from type-I DSMs with a pair of Dirac points on the rotation\naxis of the crystals.",
        "positive": "2D transport and screening in topological insulator surface states: We study disorder effects on the surface states of the topological insulator\nBi$_2$Se$_3$ close to the topologically protected crossing point. Close to\ncharge neutrality, local fluctuations in carrier density arising from the\nrandom charged disorder in the environment result in electron and hole puddles\nthat dominate the electronic properties of these materials. By calculating the\npolarizability of the surface state using the random phase approximation, and\ndetermining the characteristics of puddles using the self-consistent\napproximation, we find that band asymmetry plays a crucial role in determining\nexperimentally measured quantities including the conductivity and the puddle\nautocorrelation length."
    },
    {
        "anchor": "Generation of Schr\u00f6dinger cat states through photon-assisted\n  Landau-Zener-St\u00fcckelberg interferometry: Schr\\\"odinger cat states are useful for many applications, ranging from\nquantum information processing to high-precision measurements. In this paper we\npropose a conceptually new method for creating such cat states, based on\nphoton-assisted Landau-Zener-St\\\"uckelberg interferometry in a hybrid system\nconsisting of a qubit coupled to a photon cavity. We show that by initializing\nthe qubit in one of its basis states, performing three consecutive sweeps of\nthe qubit energy splitting across the 1-photon resonance, and finally\nprojecting the qubit to the same basis state, the parity of the photon field\ncan be purified to very high degree; when the initial photon state is a\ncoherent state, the final state will then be very close to a Schr\\\"odinger cat\nstate. We present numerical simulations that confirm that our protocol could\nwork with high fidelity ($\\sim 0.99$) for coherent states of reasonable size\n($|\\alpha|^2 \\sim 10$). Furthermore, we suggest that our protocol can also be\nused to transfer quantum information between the qubit and a superposition of\northogonal cat states in the cavity.",
        "positive": "Non-Hermitian band topology with generalized inversion symmetry: Non-Hermitian skin effects and exceptional points are topological phenomena\ncharacterized by integer winding numbers. In this study, we give methods to\ntheoretically detect skin effects and exceptional points by generalizing\ninversion symmetry. The generalization of inversion symmetry is unique to\nnon-Hermitian systems. We show that parities of the winding numbers can be\ndetermined from energy eigenvalues on the inversion-invariant momenta when\ngeneralized inversion symmetry is present. The simple expressions for the\nwinding numbers allow us to easily analyze skin effects and exceptional points\nin non-Hermitian bands. We also demonstrate the methods for (second-order) skin\neffects and exceptional points by using lattice models."
    },
    {
        "anchor": "Reply to Comment on \"Continuous quantum measurement: inelastic tunneling\n  and lack of current oscillations\": We reply to a comment by Averin and Korotkov\nhttp://uk.arxiv.org/abs/cond-mat/0404549 on Stace and Barrett, PRL 92, 136802\n(2004) http://link.aps.org/abstract/PRL/v92/e136802, showing that their\nspecific criticisms are unfounded, and clarifying some of our results.",
        "positive": "Orbital-free approach for large-scale electrostatic simulations of\n  quantum nanoelectronics devices: The route to reliable quantum nanoelectronic devices hinges on precise\ncontrol of the electrostatic environment. For this reason, accurate methods for\nelectrostatic simulations are essential in the design process. The most\nwidespread methods for this purpose are the Thomas-Fermi approximation, which\nprovides quick approximate results, and the Schr\\\"odinger-Poisson method, which\nbetter takes into account quantum mechanical effects. The mentioned methods\nsuffer from relevant shortcomings: the Thomas-Fermi method fails to take into\naccount quantum confinement effects that are crucial in heterostructures, while\nthe Schr\\\"odinger-Poisson method suffers severe scalability problems. This\npaper outlines the application of an orbital-free approach inspired by density\nfunctional theory. By introducing gradient terms in the kinetic energy\nfunctional, our proposed method incorporates corrections to the electronic\ndensity due to quantum confinement while it preserves the scalability of a\ntheory that can be expressed as a functional minimization problem. This method\noffers a new approach to addressing large-scale electrostatic simulations of\nquantum nanoelectronic devices."
    },
    {
        "anchor": "Decoherence measurements in crystals of molecular magnets: Decoherence processes in crystals of molecular magnets are prototypical for\ninteracting electronic spin systems. We analyze the Landau-Zener dynamics of\nthe archetypical TbPc$_2$ complex diluted in a diamagnetic monocrystal. The\ndependence of the tunneling probability on the field sweep rate is evaluated in\nthe framework of the recently proposed master equation in which the decoherence\nprocesses are described through a phenomenological Lindblad operator. Thus, we\nshowcase low temperature magnetic measurements that complement resonant\ntechniques in determining small tunnel splittings and dephasing times.",
        "positive": "Additional excitonic features and momentum-dark states in ReS2: Unidirectional in-plane structural anisotropy in Rhenium-based transition\nmetal dichalcogenides (TMDs) introduces a new class of 2-D materials,\nexhibiting anisotropic optical properties. In this work, we perform temperature\ndependent, polarization-resolved photoluminescence and reflectance measurements\non several-layer ReS$_{2}$. We discover two additional excitonic resonances\n(X$_{3}$ and X$_{4}$), which can be attributed to splitting of spin degenerate\nstates. Strong in-plane oscillator strength of exciton species X$_{1}$ and\nX$_{2}$ are accompanied by weaker counterparts X$_{3}$ and X$_{4}$ with similar\npolarization orientations. The in-plane anisotropic dielectric function has\nbeen obtained for ReS$_{2}$ which is essential for engineering light matter\ncoupling for polarization sensitive optoelectronic devices. Furthermore, our\ntemperature dependent study revealed the existence of low-lying\nmomentum-forbidden dark states causing an anomalous PL intensity variation at\n30 K, which has been elucidated using a rate equation model involving phonon\nscattering from these states. Our findings of the additional excitonic features\nand the momentum-dark states can shed light on the true nature of the\nelectronic band structure of ReS$_{2}$."
    },
    {
        "anchor": "Theory of Josephson transport through spintronics nano-structure: We study the Josephson transport through ferromagnetic insulators (FIs) by\ntaking into account its band structure explicitly. In the case of the fully\npolarized FIs (FPFIs), we found the formation of a pi-junction and an\natomic-scale 0-pi transition induced by increasing the FI thickness. More\nremarkably, in the Josephson junction through spin-filter materials such as Eu\nchalcogenides, the orbital hybridization between the conduction d and the\nlocalized f electron gives rise to the pi-junction behavior. Such FI-based\npi-junctions can be used to implement highly-coherent solid-state quantum bits.",
        "positive": "Conditions for requiring nonlinear thermoelectric transport theory in\n  nanodevices: In this paper, we examine the conditions under which the nonlinear transport\ntheory is inescapable, when a correlated quantum dot is symmetrically coupled\nto two leads submitted to temperature and voltage biases. By detailed numerical\ncomparisons between nonlinear and linear currents, we show that the claimed\nnonlinear behavior in a temperature gradient for the electric current is not so\ngenuine, and the linear theory made at the operating temperature $\\bar{T}=\n(T_H+T_C)/2$ is unexpectedly robust. This is demonstrated for the single\nimpurity Anderson model, in different regimes: resonant tunneling, Coulomb\nblockade and Kondo regimes."
    },
    {
        "anchor": "Towards a Graphene-Based Quantum Impedance Standard: Precision measurements of the quantum Hall resistance with alternating\ncurrent (ac) in the kHz range were performed on epitaxial graphene in order to\nassess its suitability as a quantum standard of impedance. The quantum Hall\nplateaus measured with alternating current were found to be flat within one\npart in 10^7. This is much better than for plain GaAs quantum Hall devices and\nshows that the magnetic-flux-dependent capacitive ac losses of the graphene\ndevice are less critical. The observed frequency dependence of about\n-8x10^-8/kHz is comparable in absolute value to the positive frequency\ndependence of plain GaAs devices, but the negative sign is attributed to stray\ncapacitances which we believe can be minimized by a careful design of the\ngraphene device. Further improvements thus may lead to a simpler and more\nuser-friendly quantum standard for both resistance and impedance.",
        "positive": "High-Frequency Microstrip Cross Resonators for Circular Polarization EPR\n  Spectroscopy: In this article we discuss the design and implementation of a novel\nmicrostrip resonator which allows for the absolute control of the microwaves\npolarization degree for frequencies up to 30 GHz. The sensor is composed of two\nhalf-wavelength microstrip line resonators, designed to match the 50 Ohms\nimpedance of the lines on a high dielectric constant GaAs substrate. The line\nresonators cross each other perpendicularly through their centers, forming a\ncross. Microstrip feed lines are coupled through small gaps to three arms of\nthe cross to connect the resonator to the excitation ports. The control of the\nrelative magnitude and phase between the two microwave stimuli at the input\nports of each line allows for tuning the degree and type of polarization of the\nmicrowave excitation at the center of the cross resonator. The third (output)\nport is used to measure the transmitted signal, which is crucial to work at low\ntemperatures, where reflections along lengthy coaxial lines mask the signal\nreflected by the resonator. EPR spectra recorded at low temperature in an S=\n5/2 molecular magnet system show that 82%-fidelity circular polarization of the\nmicrowaves is achieved over the central area of the resonator."
    },
    {
        "anchor": "From edge to bulk: Cavity induced displacement of topological non-local\n  qubits: We investigate the ability of selective cavity coupling to a topological\nchain for tailoring the connectivity of Majorana fermions. We show how\ntopological qubits (TQs), associated with non-local Majorana fermion pairing,\ncan be moved from the edge to the bulk of a topological chain through selective\naccess to light-matter interaction with specific physical sites. In particular,\nwe present a comprehensive DMRG study of ground-state features in different\nchain-cavity coupling geometries and validate analytical insights in the strong\ncoupling regime. This new kind of Majorana fermion correlation generation\nprocess comes with new cavity photon features. Moreover, by considering the\ntime evolution after a sudden quench of the cavity-matter coupling strength, we\nshow that the development of high non-trivial matter (Majorana) correlations\nleaves off measurable non-classical photon imprints in the cavity. New ways to\ndynamically generate TQ nonlocal correlations in topological chains of\narbitrary length are thus provided, opening alternative routes to controllable\nlong-range entanglement in hybrid photonic solid-state systems.",
        "positive": "Influence of an embedded quantum dot on the Josephson effect in the\n  topological superconducting junction with Majorana doublets: One Majorana doublet can be realized at each end of the\ntime-reversal-invariant Majorana nanowires. We investigate the Josephson effect\nin the Majorana-doublet-presented junction modified by different inter-doublet\ncoupling manners. It is found that when the Majorana doublets couple indirectly\nvia a non-magnetic quantum dot, only the normal Josephson effects occur, and\nthe fermion parity in the system just affects the current direction and\namplitude. However, in the odd-parity case, applying finite magnetic field on\nthe quantum dot can induce the appearance of the fractional Josephson effect.\nNext, when the direct and indirect couplings between the Majorana doublets\ncoexist, no fractional Josephson effect takes place, regardless of finite\nmagnetic field on the quantum dot. Instead, the $\\pi$-period current has an\nopportunity to appear in some special cases. All the results are clarified by\nanalyzing the influence of the fermion occupation in the quantum dot on the\nparity conservation in the whole system. We ascertain that this work will be\nhelpful for describing the dot-assisted Josephson effect between the Majorana\ndoublets."
    },
    {
        "anchor": "Efficient quantum transport simulation for bulk graphene heterojunctions: The quantum transport formalism based on tight-binding models is known to be\npowerful in dealing with a wide range of open physical systems subject to\nexternal driving forces but is, at the same time, limited by the memory\nrequirement's increasing with the number of atomic sites in the scattering\nregion. Here we demonstrate how to achieve an accurate simulation of quantum\ntransport feasible for experimentally sized bulk graphene heterojunctions at a\nstrongly reduced computational cost. Without free tuning parameters, we show\nexcellent agreement with a recent experiment on Klein backscattering [A. F.\nYoung and P. Kim, Nature Phys. 5, 222 (2009)].",
        "positive": "Size-induced structural phase transition at ~6.0 nm from mixed fcc-hcp\n  to purely fcc structure in monodispersed nickel nanoparticles: We have investigated the core issue of atomic lattices in monodispersed Ni\nnanoparticles (NPs) of sizes 3.8 nm to 10.1 nm using detailed analysis of X-ray\ndiffraction, synchrotron radiation X-ray absorption spectroscopy (XAS) and\nmagnetization data. This has revealed the very remarkable coexistence of atomic\nface-centered cubic (fcc) and hexagonal closed-packed (hcp) lattices in samples\nwith particle size less than or equal to 6.0 nm with the prevalence of only fcc\nphase beyond this. They are also associated with reduced coordination number,\nmodified electronic structure, and surface atom coordination with ligands.\nMagnetization data furthermore reveal coexistence of ferromagnetism and\nsuperparamagnetism at 300 K. Considered to be due to dominant roles of ligands,\nthey are likely to open up far-reaching implications to their future\napplications."
    },
    {
        "anchor": "Magnetic field control of intersubband polaritons in narrow-gap\n  semiconductors: We investigate theoretically the polariton coupling between the light\nconfined in a planar cavity and the intersubband transitions of a\ntwo-dimensional electron gas confined in semiconductor quantum wells in the\npresence of a vertical magnetic field. We show that in heterostructures made of\nnon-parabolic semiconductors, the polaritons do not fit a two-level problem,\nsince the cavity photons couple to a non-degenerate ensemble of intersubband\ntransitions. As a consequence, the stationary polariton eigenstates become very\nsensitive to the vertical magnetic field, which thus plays the role of an\nexternal parameter that controls the regime of light-matter interactions. At\nintermediate field strength we predict that the magneto-polaritons have energy\ndispersions ideally suited to parametric amplification.",
        "positive": "Indirect-to-direct bandgap transition in few-layer $\u03b2$-InSe as\n  probed by photoluminescence spectroscopy: InSe is a promising material for a next-generation of two-dimensional\nelectronic and optical devices, characteristics of which are largely determined\nby the type of band structure, direct or indirect. In general, different\nmethods can be sensitive to different peculiarities of the electronic structure\nleading to different results. In this work, we will focus on the luminescent\nproperties of few-layer $\\beta$-InSe with a thickness of 6 to 75 monolayers\n(ML). Low-temperature micro-photoluminescence ($mu$-PL) studies show a sharp\nincrease in PL intensity in the range of thicknesses from 16 to 20 monolayers,\nwhere, in addition, there is a singularity in the dependence of the work\nfunction on the thickness. Time-resolved photoluminescence spectroscopy (TRPL)\nreveals three characteristic PL decay times that differ from each other by\nabout an order of magnitude. We associate the processes underlying the two\nfaster decays with the recombination of electrons and holes between the band\nextrema, either directly or through the interband relaxation of holes. Their\ncontributions to the total PL intensity increase significantly in the same\nthickness range, 16-20 MLs. On the contrary, the slowest contribution, which we\nattribute mainly to the defect-assisted recombination, prevails at a smaller\nnumber of monolayers and then noticeably decreases. These results indicate the\nindirect-to-direct bandgap transition near 16-20 MLs, which determines the\nrange of applicability of a few-layer $\\beta$-InSe for efficient light\nemitters."
    },
    {
        "anchor": "Probing the local temperature of a 2DEG microdomain with a quantum dot:\n  measurement of electron-phonon interaction: We demonstrate local detection of the electron temperature in a\ntwo-dimensionalmicrodomain using a quantum dot. Our method relies on the\nobservation that a temperature bias across the dot changes the functional form\nof Coulomb-blockade peaks. We apply our results to the investigation of\nelectron-energy relaxation at subkelvin temperatures, find that the energy flux\nfrom electrons into phonons is proportional to the fifth power of temperature,\nand give a measurement of the coupling constant.",
        "positive": "Thermodynamic uncertainty relations for systems with broken time\n  reversal symmetry: the case of superconducting hybrid systems: We derive bounds to the thermodynamic uncertainty relations in the\nlinear-response regime for steady-state transport in two-terminal systems when\ntime reversal symmetry is broken. We find that such bounds are different for\ncharge and heat currents and depend on the details of the system, through the\nOnsager coefficients, and on the ratio between applied voltage and temperature\ndifference. As a function of such a ratio, the bounds can take any positive\nvalues. The bounds are then calculated for a hybrid coherent superconducting\nsystem using the scattering approach, and the concrete case of an Andreev\ninterferometer is explored. Interestingly, we find that the bound on the charge\ncurrent is always smaller than 2 when the system operates as a heat engine,\nwhile the bound on the heat current is always larger than 2 when the system\noperates as a refrigerator."
    },
    {
        "anchor": "Sub-Nanosecond Spin-Transfer Torque in an Ensemble of\n  Superparamagnetic-Like Nanomagnets: Spin currents can exert spin-transfer torques on magnetic systems even in the\nlimit of vanishingly small net magnetization, as is the case for\nantiferromagnets. Here, we experimentally show that a spin-transfer torque is\noperative in a material with weak, short-range magnetic order -- namely, a\nmacroscopic ensemble of superparamagnetic-like Co nanomagnets. We employ\nelement- and time-resolved X-ray ferromagnetic resonance (XFMR) spectroscopy to\ndirectly detect sub-ns dynamics of the Co nanomagnets, excited into precession\nwith cone angle $\\geq$0.003$^{\\circ}$ by an oscillating spin current. XFMR\nmeasurements reveal that as the net moment of the ensemble decreases, the\nstrength of the spin-transfer torque increases relative to those of magnetic\nfield torques. Our findings point to spin-transfer torque as an effective way\nto manipulate the state of nanomagnet ensembles at sub-ns timescales.",
        "positive": "Piezoplasmonics: strain-induced tunability of plasmon resonance in AlAs\n  quantum wells: We demonstrate tuning of two-dimensional (2D) plasmon spectrum in\nmodulation-doped AlAs quantum wells via the application of in-plane uniaxial\nstrain. We show that dramatic change in the plasma spectrum is caused by\nstrain-induced redistribution of charge carriers between anisotropic $X_x$ and\n$X_y$ valleys. Discovered piezoplasmonic effect provides a tool to study the\nband structure of 2D systems. We use piezoplasmonic effect to measure how the\ninter-valley energy splitting depends on the deformation. This dependency\nyields the AlAs deformation potential of $E_2 = (5.6 \\pm 0.3)$~eV."
    },
    {
        "anchor": "Scattering of a Dirac electron on a mass barrier: The interaction of a wave packet (and in particular the wave front) with a\nmass barrier is investigated in one dimension. We discuss the main features of\nthe wave packet that are inherent to two-dimensional wave packets, such as\ncompression during reflection, penetration in the case when the energy is lower\nthan the height of the barrier, waving tails, precursors, and the retardation\nof the reflected and penetrated wave packets. These features depend on the\nwave-packet envelope function which we demonstrate by considering the case of a\nrectangular wave packet with sharp front and trailing edges and a smooth\nGaussian wave packet. The method of Fourier integral for obtaining the\nnonstationary solutions is used.",
        "positive": "Frictional Drag between Two Dilute Two-Dimensional Hole Layers: We report drag measurements on dilute double layer two-dimensional hole\nsystems in the regime of r_s=19~39. We observed a strong enhancement of the\ndrag over the simple Boltzmann calculations of Coulomb interaction, and\ndeviations from the T^2 dependence which cannot be explained by\nphonon-mediated, plasmon-enhanced, or disorder-related processes. We suggest\nthat this deviation results from interaction effects in the dilute regime."
    },
    {
        "anchor": "Anyonic interference and braiding phase in a Mach-Zehnder Interferometer: The fractional quantum Hall states have long been predicted to be a testing\nground of fractional (anyonic) exchange statistics. These topological states\nharbor quasiparticles with fractional charges of both abelian and non-abelian\ncharacters. The quasiparticles' charge is commonly determined by shot noise\nmeasurements (1, 2), and states' statistics can be revealed by appropriately\ninterfering the quasiparticles. While the multipath Fabry-Perot electronic\ninterferometer (FPI) is easier to fabricate, it is often plagued by Coulomb\ninteractions (3), its area breathes with the magnetic field (4), and its bulk's\ncharges tend to fluctuate (5). Recent FPI experiments employing adequate\nscreening allowed an observation of Aharonov-Bohm (AB) interference at bulk\nfilling $\\nu$=1/3 (6). In the current work, we chose to employ an\ninteraction-free, two-path, Mach-Zehnder interferometer (MZI), tuned to bulk\nfilling $\\nu$=2/5. Interfering the outer $\\nu$=1/3 mode (with the inner\n$\\nu$=1/15 mode screening out the bulk), we observed a 'dressed AB'\nperiodicity, with a combined 'bare AB' flux periodicity of three flux-quanta\n(3$\\phi_0$) and the 'braiding phase' 2$\\pi$/3. This unique interference\nresulted with an AB periodicity of a single flux-quantum. Moreover, the\nvisibility of the interference, $v_{e/3}$, deviated markedly from that of the\nelectronic one $\\it{v}_{e}$, agreeing with the theoretically expected\nvisibility, $\\it{v}_{e/3} \\sim {\\it{v}_e}^3$. With the two non-equivalent\ndrains of the MZI, the fractional visibility peaked away from the ubiquitous\ntransmission-half of the MZI. We provide simple theoretical arguments that\nsupport our results. The MZI proves to be a powerful tool that can be used to\nprobe further the statistics of more complex anyonic quasiparticles.",
        "positive": "Helimagnetic thin films: surface reconstruction, surface spin-waves and\n  magnetization: Quantum properties of a helimagnetic thin film of simple cubic lattice with\nHeisenberg spin model are studied using the Green's function method. We find\nthat the spin configuration across the film is strongly non uniform. Using the\nexactly determined spin configuration we calculate the spin-wave spectrum and\nthe layer magnetizations as functions of temperature T. We show the existence\nof surface-localized modes which strongly affect the surface magnetization. We\nalso show that quantum fluctuations cause interesting spin contractions at T =\n0 and give rise to a cross-over between layer magnetizations at low T ."
    },
    {
        "anchor": "Kondo resonance effect on persistent currents through a quantum dot in a\n  mesoscopic ring: The persistent current through a quantum dot inserted in a mesoscopic ring of\nlength L is studied. A cluster representing the dot and its vicinity is exactly\ndiagonalized and embedded into the rest of the ring. The Kondo resonance\nprovides a new channel for the current to flow. It is shown that due to scaling\nproperties, the persistent current at the Kondo regime is enhanced relative to\nthe current flowing either when the dot is at resonance or along a perfect ring\nof same length. In the Kondo regime the current scales as $L^{-1/2}$, unlike\nthe $L^{-1}$ scaling of a perfect ring. We discuss the possibility of detection\nof the Kondo effect by means of a persistent current measurement.",
        "positive": "Polariton Laser in the Bardeen-Cooper-Schrieffer Regime: Microcavity exciton polariton systems can have a wide range of macroscopic\nquantum effects that may be turned into better photonic technologies. Polariton\nBose-Einstein condensation and photon lasing have been widely accepted in the\nlimits of low and high carrier densities, but identification of the expected\nBardeen-Cooper-Schrieffer (BCS) state at intermediate densities remains\nelusive, as the optical-gain mechanism cannot be directly inferred from\nexisting experiments. Here, using a microcavity with strong polarization\nselectivity, we gain direct experimental access to the reservoir absorption in\nthe presence of polariton condensation and lasing, which reveals a fermionic\ngain mechanism underlying the polariton laser. A microscopic many-particle\ntheory shows that this polariton lasing state is consistent with an\nopen-dissipative-pumped system analog of a polaritonic BCS state."
    },
    {
        "anchor": "Hall viscosity, orbital spin, and geometry: paired superfluids and\n  quantum Hall systems: The Hall viscosity, a non-dissipative transport coefficient analogous to Hall\nconductivity, is considered for quantum fluids in gapped or topological phases.\nThe relation to mean orbital spin per particle discovered in previous work by\none of us is elucidated with the help of examples, using the geometry of shear\ntransformations and rotations. For non-interacting particles in a magnetic\nfield, there are several ways to derive the result (even at non-zero\ntemperature), including standard linear response theory. Arguments for the\nquantization, and the robustness of Hall viscosity to small changes in the\nHamiltonian that preserve rotational invariance, are given. Numerical\ncalculations of adiabatic transport are performed to check the predictions for\nquantum Hall systems, with excellent agreement for trial states. The\ncoefficient of k^4 in the static structure factor is also considered, and shown\nto be exactly related to the orbital spin and robust to perturbations in\nrotation invariant systems also.",
        "positive": "Revised theoretical limit of subthreshold swing in field-effect\n  transistors: This letter reports a temperature-dependent limit for the subthreshold swing\nin MOSFETs that deviates from the Boltzmann limit at deep-cryogenic\ntemperatures. Below a critical temperature, the derived limit saturates to a\nvalue that is independent of temperature and proportional to the extent of a\nband tail. Since the saturation is universally observed in different types of\nMOSFETs (regardless of dimension or semiconductor material), the band tail is\nattributed to the finite periodicity of the lattice in a semiconductor volume,\nand to a lesser extent to additional lattice perturbations such as defects or\ndisorder."
    },
    {
        "anchor": "Terahertz Antiferromagnetic Spin Hall Nano-Oscillator: We consider the current-induced dynamics of insulating antiferromagnets in a\nspin Hall geometry. Sufficiently large in-plane currents perpendicular to the\nN\\'{e}el order trigger spontaneous oscillations at frequencies between the\nacoustic and the optical eigenmodes. The direction of the driving current\ndetermines the chirality of the excitation. When the current exceeds a\nthreshold, the combined effect of spin pumping and current-induced torques\nintroduces a dynamic feedback that sustains steady-state oscillations with\namplitudes controllable via the applied current. The ac voltage output is\ncalculated numerically as a function of the dc current input for different\nfeedback strengths. Our findings open a route towards terahertz\nantiferromagnetic spin-torque oscillators.",
        "positive": "$\\mathcal{P}\\mathcal{T}$-symmetric topological phases with Pontryagin\n  index in three spatial dimensions: We report on a certain class of three-dimensional topological insulators and\nsemimetals protected by spinless $\\mathcal{P}\\mathcal{T}$ symmetry, hosting an\ninteger-valued bulk invariant. We show using homotopy arguments that these\nphases host multi-gap topology, providing a realization of a single\n$\\mathbb{Z}$ invariant in three spatial dimensions that is distinct from the\nHopf index. We identify this invariant with the Pontryagin index, which\ndescribes BPST instantons in particle physics contexts and corresponds to a\n3-sphere winding number. We study naturally arising multi-gap linked nodal\nrings, topologically characterized by split-biquaternion charges, which can be\nremoved by non-Abelian braiding of nodal rings, even without closing a gap. We\nadditionally connect the describing winding number in terms of gauge-invariant\ncombinations of non-Abelian Berry connection elements, indicating relations to\nPontryagin characteristic class in four dimensions. These topological\nconfigurations are furthermore related to fully non-degenerate multi-gap phases\nthat are characterized by a pair of winding numbers relating to two isoclinic\nrotations in the case of four bands and can be generalized to an arbitrary\nnumber of bands. From a physical perspective, we also analyze the edge states\ncorresponding to this Pontryagin index as well as their dissolution subject to\nthe gap-closing disorder. Finally, we elaborate on the realization of these\nnovel non-Abelian phases, their edge states and linked nodal structures in\nacoustic metamaterials and trapped-ion experiments."
    },
    {
        "anchor": "Numerical method for hydrodynamic modulation equations describing Bloch\n  oscillations in semiconductor superlattices: We present a finite difference method to solve a new type of nonlocal\nhydrodynamic equations that arise in the theory of spatially inhomogeneous\nBloch oscillations in semiconductor superlattices. The hydrodynamic equations\ndescribe the evolution of the electron density, electric field and the complex\namplitude of the Bloch oscillations for the electron current density and the\nmean energy density. These equations contain averages over the Bloch phase\nwhich are integrals of the unknown electric field and are derived by singular\nperturbation methods. Among the solutions of the hydrodynamic equations, at a\n70 K lattice temperature, there are spatially inhomogeneous Bloch oscillations\ncoexisting with moving electric field domains and Gunn-type oscillations of the\ncurrent. At higher temperature (300 K) only Bloch oscillations remain. These\nnovel solutions are found for restitution coefficients in a narrow interval\nbelow their critical values and disappear for larger values. We use an\nefficient numerical method based on an implicit second-order finite difference\nscheme for both the electric field equation (of drift-diffusion type) and the\nparabolic equation for the complex amplitude. Double integrals appearing in the\nnonlocal hydrodynamic equations are calculated by means of expansions in\nmodified Bessel functions. We use numerical simulations to ascertain the\nconvergence of the method. If the complex amplitude equation is solved using a\nfirst order scheme for restitution coefficients near their critical values, a\nspurious convection arises that annihilates the complex amplitude in the part\nof the superlattice that is closer to the cathode. This numerical artifact\ndisappears if the space step is appropriately reduced or we use the\nsecond-order numerical scheme.",
        "positive": "Optical measurement and modeling of interactions between two hole or two\n  electron spins in coupled InAs quantum dots: Two electron spins in quantum dots coupled through coherent tunneling are\ngenerally acknowledged to approximately obey Heisenberg isotropic exchange.\nThis has not been established for two holes. Here we measure the spectra of two\nholes and of two electrons in two vertically stacked self-assembled InAs\nquantum dots using optical spectroscopy as a function of electric and magnetic\nfields. We find that the exchange is approximately isotropic for both systems,\nbut that significant asymmetric contributions, arising from spin-orbit and\nZeeman interactions combined with spatial asymmetries, are required to explain\nlarge anticrossings and fine-structure energy splittings in the spectra.\nAsymmetric contributions to the isotropic Hamiltonian for electrons are of the\norder of a few percent while those for holes are an order of magnitude larger."
    },
    {
        "anchor": "Formation of the Pd atomic chain in hydrogen atmosphere: The formation of a Pd atomic chain in a hydrogen atmosphere was investigated\nby measurements of conductance and vibrational spectroscopy of a single\nmolecular junction, and the theoretical calculation. While atomic chains were\nnot formed for clean 3d and 4d metals, in the case of Pd (a 4d metal) atomic\nchains could be formed in the presence of hydrogen. Stable atomic chains with\ntwo different atomic configurations were formed when the Pd atomic contact was\nstretched in a H$_{2}$ atmosphere; highly conductive short hydrogen adsorbed\natomic chain and low conductive long hydrogen incorporated atomic chain.",
        "positive": "Fano-Rashba effect in quantum dots: We consider the electronic transport through a Rashba quantum dot coupled to\nferromagnetic leads. We show that the interference of localized electron states\nwith resonant electron states leads to the appearance of the Fano-Rashba\neffect. This effect occurs due to the interference of bound levels of\nspin-polarized electrons with the continuum of electronic states with an\nopposite spin polarization. We investigate this Fano-Rashba effect as a\nfunction of the applied magnetic field and Rashba spin-orbit coupling."
    },
    {
        "anchor": "Photoinduced interfacial chiral modes in threefold topological semimetal: We investigate the chiral electronic modes at the interface between two\nregions of a threefold topological semimetal, which is illuminated by left and\nright handed elliptically polarized waves. The radiation effects on the band\nstructure of semimetal is analyzed by using Floquet theory. Two distinct\nsolutions of the interface modes are found with the chirality depending on the\nphase of the irradiation. We also consider the anomalous Hall response which is\nattributed to the transition between dispersionless flat band and conic bands.",
        "positive": "Strong transient magnetic fields induced by THz-driven plasmons in\n  graphene disks: Strong circularly polarized excitation opens up the possibility to generate\nand control effective magnetic fields in solid state systems, e.g., via the\noptical inverse Faraday effect or the phonon inverse Faraday effect. While\nthese effects rely on material properties that can be tailored only to a\nlimited degree, plasmonic resonances can be fully controlled by choosing proper\ndimensions and carrier concentrations. Plasmon resonances provide new degrees\nof freedom that can be used to tune or enhance the light-induced magnetic field\nin engineered metamaterials. Here we employ graphene disks to demonstrate\nlight-induced transient magnetic fields from a plasmonic circular current with\nextremely high efficiency. The effective magnetic field at the plasmon\nresonance frequency of the graphene disks (3.5 THz) is evidenced by a strong\n(~1{\\deg}) ultrafast Faraday rotation (~ 20 ps). In accordance with reference\nmeasurements and simulations, we estimated the strength of the induced magnetic\nfield to be on the order of 0.7 T under a moderate pump fluence of about 440 nJ\ncm-2."
    },
    {
        "anchor": "Electron-vibron coupling in suspended carbon nanotube quantum dots: Motivated by recent experiments, we investigate the electron-vibron coupling\nin suspended carbon nanotube quantum dots, starting with the electron-phonon\ncoupling of the underlying graphene layer. We show that the coupling strength\ndepends sensitively on the type of vibron and is strongly sample dependent. The\ncoupling strength becomes particularly strong when inhomogeneity-induced\nelectronic quantum dots are located near regions where the vibronic mode is\nassociated with large strain. Specifically, we find that the longitudinal\nstretching mode and the radial breathing mode are coupled via the strong\ndeformation potential, while twist modes couple more weakly via a mechanism\ninvolving modulation of the electronic hopping amplitudes between carbon sites.\nA special case are bending modes: for symmetry reasons, their coupling is only\nquadratic in the vibron coordinate. Our results can explain recent experiments\non suspended carbon nanotube quantum dots which exibit vibrational sidebands\naccompanied by the Franck-Condon blockade with strong electron-vibron coupling.",
        "positive": "Giant Thermoelectric Effect from Transmission Supernodes: We predict an enormous order-dependent quantum enhancement of thermoelectric\neffects in the vicinity of a higher-order `supernode' in the transmission\nspectrum of a nanoscale junction. Single-molecule junctions based on\n3,3'-biphenyl and polyphenyl ether (PPE) are investigated in detail. The\nnonequilibrium thermodynamic efficiency and power output of a thermoelectric\nheat engine based on a 1,3-benzene junction are calculated using many-body\ntheory, and compared to the predictions of the figure-of-merit ZT."
    },
    {
        "anchor": "Spin splitting and even-odd effects in carbon nanotubes: The level spectrum of a single-walled carbon nanotube rope, studied by\ntransport spectroscopy, shows Zeeman splitting in a magnetic field parallel to\nthe tube axis. The pattern of splittings implies that the spin of the ground\nstate alternates by 1/2 as consecutive electrons are added. Other aspects of\nthe Coulomb blockade characteristics, including the current-voltage traces and\npeak heights, also show corresponding even-odd effects.",
        "positive": "Nuclear Spins in Nanostructures: We review recent theoretical and experimental advances toward understanding\nthe effects of nuclear spins in confined nanostructures. These systems, which\ninclude quantum dots, defect centers, and molecular magnets, are particularly\ninteresting for their importance in quantum information processing devices,\nwhich aim to coherently manipulate single electron spins with high precision.\nOn one hand, interactions between confined electron spins and a nuclear-spin\nenvironment provide a decoherence source for the electron, and on the other, a\nstrong effective magnetic field that can be used to execute local coherent\nrotations. A great deal of effort has been directed toward understanding the\ndetails of the relevant decoherence processes and to find new methods to\nmanipulate the coupled electron-nuclear system.\n  A sequence of spectacular new results have provided understanding of\nspin-bath decoherence, nuclear spin diffusion, and preparation of the nuclear\nstate through dynamic polarization and more general manipulation of the\nnuclear-spin density matrix through \"state narrowing\". These results\ndemonstrate the richness of this physical system and promise many new mysteries\nfor the future."
    },
    {
        "anchor": "Dynamical Mean-Field Theory for Molecular Electronics: Electronic\n  Structure and Transport Properties: We present an approach for calculating the electronic structure and transport\nproperties of nanoscopic conductors that takes into account the dynamical\ncorrelations of strongly interacting d- or f-electrons by combining density\nfunctional theory calculations with the dynamical mean-field theory. While the\ndensity functional calculation yields a static mean-field description of the\nweakly interacting electrons, the dynamical mean-field theory explicitly takes\ninto account the dynamical correlations of the strongly interacting d- or\nf-electrons of transition metal atoms. As an example we calculate the\nelectronic structure and conductance of Ni nanocontacts between Cu electrodes.\nWe find that the dynamical correlations of the Ni 3d-electrons give rise to\nquasi-particle resonances at the Fermi-level in the spectral density. The\nquasi-particle resonances in turn lead to Fano lineshapes in the conductance\ncharacteristics of the nanocontacts similar to those measured in recent\nexperiments of magnetic nanocontacts.",
        "positive": "The Simulation of Non-Abelian Statistics of Majorana Fermions in Ising\n  Chain with Z2 Symmetry: In this paper, we numerically study the non-Abelian statistics of the\nzero-energy Majorana fermions on the end of Majorana chain and show its\napplication to quantum computing by mapping it to a spin model with special\nsymmetry. In particular, by using transverse-field Ising model with Z2\nsymmetry, we verify the nontrivial non-Abelian statistics of Majorana fermions.\nNumerical evidence and comparison in both Majorana-representation and\nspin-representation are presented. The degenerate ground states of a symmetry\nprotected spin chain therefore previde a promising platform for topological\nquantum computation."
    },
    {
        "anchor": "Realization and Topological Properties of Third-Order Exceptional Lines\n  Embedded in Exceptional Surfaces: As the counterpart of Hermitian nodal structures, the geometry formed by\nexceptional points (EPs), such as exceptional lines (ELs), entails intriguing\nspectral topology. We report the experimental realization of order-3\nexceptional lines (EL3) that are entirely embedded in order-2 exceptional\nsurfaces (ES2) in a three-dimensional periodic synthetic momentum space. The\nEL3 and the concomitant ES2, together with the topology of the underlying\nspace, prohibit the evaluation of their topology in the eigenvalue manifold by\nprevailing topological characterization methods. We resolve this issue by\ndefining a winding number that associates with the resultants of the\nHamiltonian. This resultant winding number detects EL3 but ignores the ES2,\nallowing the diagnosis of the topological currents carried by the EL3, which\nenables the prediction of their evolution under perturbations. Our results\nexemplify unprecedented topology of higher-order exceptional geometries and may\ninspire new non-Hermitian topological applications.",
        "positive": "Optical properties and carrier dynamics in Co-doped ZnO nanorods: The controlled modification of the electronic properties of ZnO nanorods via\ntransition metal doping is reported. A series of ZnO nanorods were synthesized\nby chemical bath growth with varying Co content from 0 to 20 atomic % in the\ngrowth solution. Optoelectronic behavior was probed using cathodoluminescence,\ntime-resolved luminescence, transient absorbance spectroscopy, and the incident\nphoton-to-current conversion efficiency (IPCE). Analysis indicates the crucial\nrole of surface defects in determining the electronic behavior. Significantly,\nCo-doping extends the light absorption of the nanorods into the visible region,\nincreases the surface defects, shortens the non-radiative lifetimes, while\nleaving the radiative lifetime constant. Furthermore, for 1 atomic % Co-doping\nthe IPCE of the ZnO nanorods is enhanced. These results demonstrate that doping\ncan controllably tune the functional electronic properties of ZnO nanorods for\napplications."
    },
    {
        "anchor": "Coupling Nitrogen Vacancy Centers in Diamond to Superconducting Flux\n  Qubits: We propose a method to achieve coherent coupling between Nitrogen-vacancy\n(NV) centers in diamond and superconducting (SC) flux qubits. The resulting\ncoupling can be used to create a coherent interaction between the spin states\nof distant NV centers mediated by the flux qubit. Furthermore, the magnetic\ncoupling can be used to achieve a coherent transfer of quantum information\nbetween the flux qubit and an ensemble of NV centers. This enables a long-term\nmemory for a SC quantum processor and possibly an interface between SC qubits\nand light.",
        "positive": "Anisotropies in the linear polarization of vacancy photoluminescence in\n  diamond induced by crystal rotations and strong magnetic fields: We study the linear polarization properties of the photoluminescence of the\nneutral and negatively charged nitrogen vacancies and neutral vacancies in\ndiamond crystals as function of their symmetry and their response to strong\nexternal magnetic fields. The linear polarization degree, which exceeds 10% at\nroom temperature, and rotation of the polarization plane of their zero-phonon\nlines significantly depend on the crystal rotation around specific axes\ndemonstrating anisotropic angular evolutions. The sign of the polarization\nplane rotation is changed periodically through the crystal rotation, which\nindicates a switching between electron excited states of orthogonal linear\npolarizations. At external magnetic fields of up to 10 T, the angular\ndependences of the linear polarization degree experience a remarkable phase\nshift. Moreover, the rotation of the linear polarization plane increases\nlinearly with rising magnetic field at 6 K and room temperature, for the\nnegatively charged nitrogen vacancies, which is attributed to magneto-optical\nFaraday rotation."
    },
    {
        "anchor": "Gate Tunable Photovoltaic Effect in MoS2 vertical P-N Homostructures: P-n junctions based on vertically stacked single or few layer transition\nmetal dichalcogenides (TMDCs) have attracted substantial scientific interest.\nDue to the propensity of TMDCs to show exclusively one type of conductivity, n-\nor p-type, heterojunctions of different materials are typically fabricated to\nproduce diode-like current rectification and photovoltaic response. Recently,\nartificial, stable and substitutional doping of MoS2 into n- and p-type has\nbeen demonstrated. MoS2 is an interesting material to use for optoelectronic\napplications due to the potential of low-cost production in large quantities,\nstrong light-matter interactions and chemical stability. Here we report the\ncharacterization of the optoelectronic properties of vertical homojunctions\nmade by stacking few-layer flakes of MoS2:Fe (n-type) and MoS2:Nb (p-type). The\njunctions exhibit a peak external quantum efficiency of 4.7 %, a maximum open\ncircuit voltage of 0.51 V, they are stable in air and their rectification\ncharacteristics and photovoltaic response are in excellent agreement to the\nShockley diode model. The gate-tunability of the maximum output power, the\nideality factor and the shunt resistance indicate that the dark current is\ndominated by trap-assisted recombination and that the photocurrent collection\ndepends strongly on the spatial extent of the space charge region. We\ndemonstrate a response time faster than 80 ms and highlight the potential to\nintegrate such devices into quasi-transparent and flexible optoelectronics.",
        "positive": "Surface and Step Conductivities on Si(111) Surfaces: Four-point measurements using a multi-tip scanning tunneling microscope (STM)\nare carried out in order to determine surface and step conductivities on\nSi(111) surfaces. In a first step, distance-dependent four-point measurements\nin the linear configuration are used in combination with an analytical\nthree-layer model for charge transport to disentangle the 2D surface\nconductivity from non-surface contributions. A termination of the Si(111)\nsurface with either Bi or H results in the two limiting cases of a pure 2D or\n3D conductance, respectively. In order to further disentangle the surface\nconductivity of the step-free surface from the contribution due to atomic\nsteps, a square four-probe configuration is applied as function of the rotation\nangle. In total this combined approach leads to an atomic step conductivity of\n$\\sigma_\\mathrm{step} = (29 \\pm 9)$ $\\mathrm{\\Omega}^{-1} \\mathrm{m}^{-1}$ and\nto a step-free surface conductivity of $\\sigma_\\mathrm{surf} = (9 \\pm 2) \\cdot\n10^{-6}\\,\\mathrm{\\Omega}^{-1}/\\square$ for the Si(111)-(7$\\times$7) surface."
    },
    {
        "anchor": "Weak Localization in Graphene: Theory, Simulations and Experiments: We provide a comprehensive picture of magnetotransport in graphene monolayers\nin the limit of non-quantizing magnetic fields. We discuss the effects of two\ncarrier transport, weak localization, weak anti-localization, and strong\nlocalization for graphene devices of various mobilities, through theory,\nexperiments and numerical simulations. In particular, we observe the weak\nlocalization of the localization length, which allows us to make the connection\nbetween weak and strong localization. It provides a unified framework for both\nlocalizations, which explains the observed experimental features. We compare\nthese results to numerical simulation and find a remarkable agreement between\ntheory, experiment and numerics. Various graphene devices were used in this\nstudy, including graphene on different substrates, such as glass and silicon,\nas well as low and high mobility devices.",
        "positive": "Acoustic mirror Chern insulator with projective parity-time symmetry: In condensed matter physics, symmetry profoundly governs the fundamentals of\ntopological matter. The emergence of new topological phase is typically linked\nto the enrichment of symmetries. Different parity-time symmetry relations\ndistinguish between spinless and spinful physical systems. In spinless systems,\ncreating pseudo-spins can realize fragile topological phase but not break the\ntime-reversal symmetry. Therefore, growing attentions were recently focused on\nthe strong topological phase in spinless systems. Here we break the framework\nof crystallographic symmetry groups by utilizing the projective symmetry gauge\nfield, to realize the Mirror Chern Insulator in a bilayer twisted Hofstadter\nmodel. In experiments, the edge modes were unambiguously observed with\nodd-shaped boundaries, confirming the strong topological features.The clockwise\nand anti-clockwise edge states with opposite group velocities were completely\nseparated via an energy drain. In addition, we demonstrate that MCI has robust\ntopological whispering gallery modes. Our work establishes a strong foundation\nfor investigating exotic topological effects arising from the interplays\nbetween artificial gauge fields and wave systems. The clockwise and\nanti-clockwise edge states with opposite group velocities were completely\nseparated via an energy drain. In addition, we demonstrate that MCI has robust\ntopological whispering gallery modes. Our work establishes a strong foundation\nfor investigating exotic topological effects arising from the interplays\nbetween artificial gauge fields and wave systems."
    },
    {
        "anchor": "Geometric Origin of Intrinsic Spin Hall Effect in an Inhomogeneous\n  Electric Field: In recent years, the spin Hall effect has received great attention because of\nits potential application in spintronics and quantum information processing and\nstorage. However, this effect is usually studied under the external homogeneous\nelectric field. Understanding how the inhomogeneous electric field affects the\nspin Hall effect is still lacking. Here, we investigate a two-dimensional\ntwo-band time-reversal symmetric system and give an expression for the\nintrinsic spin Hall conductivity in the presence of the inhomogeneous electric\nfield, which is shown to be expressed through gauge-invariant geometric\nquantities. On the other hand, when people get physical intuition on transport\nphenomena from the wave packet, one issue appears. It is shown that the\nconductivity obtained from the conventional wave packet approach cannot be\nfully consistent with the one predicted by the Kubo-Greenwood formula. Here, we\nattempt to solve this problem.",
        "positive": "Numerical study of the quantum valley Hall effect: Under more consideration, it seems that bulk valley current mediated nonlocal\nresistance is inconsistent with Landau-Buttiker formalism. We believe\nLandau-Buttiker formalism is right and the declared bulk valley current\nmediated nonlocal resistance is questionable and the experimental signal should\nbe attributed to other origins."
    },
    {
        "anchor": "Electrically-Detected ESR in Silicon Nanostructures Inserted in\n  Microcavities: We present the first findings of the new electrically-detected electron spin\nresonance technique (EDESR), which reveal the point defects in the ultra-narrow\nsilicon quantum wells (Si-QW) confined by the superconductor delta-barriers.\nThis technique allows the ESR identification without application of an external\ncavity, as well as a high frequency source and recorder, and with measuring the\nonly response of the magnetoresistance, with internal GHz Josephson emission\nwithin frameworks of the normal-mode coupling (NMC) caused by the microcavities\nembedded in the Si-QW plane.",
        "positive": "Classification of Crystalline Topological Insulators and Superconductors\n  with Point Group Symmetries: Crystalline topological phases have recently attracted a lot of experimental\nand theoretical attention. Key advances include the complete elementary band\nrepresentation analyses of crystalline matter by symmetry indicators and the\ndiscovery of higher-order hinge and corner states. However, current\nclassification schemes of such phases are either implicit or limited in scope.\nWe present a new scheme for the explicit classification of crystalline\ntopological insulators and superconductors. These phases are protected by\ncrystallographic point group symmetries and are characterized by bulk\ntopological invariants. The classification paradigm generalizes the Clifford\nalgebra extension process of each Altland-Zirnbauer symmetry class and utilizes\nalgebras which incorporate the point group symmetry. Explicit results for all\npoint group symmetries of three-dimensional crystals are presented as well as\nfor all symmorphic layer groups of two-dimensional crystals. We discuss future\nextensions for treatment of magnetic crystals and defected or\nhigher-dimensional systems as well as weak and fragile invariants."
    },
    {
        "anchor": "What is novel in quantum transport for mesoscopics?: The understanding of mesoscopic transport has now attained an ultimate\nsimplicity. Indeed, orthodox quantum kinetics would seem to say little about\nmesoscopics that has not been revealed - nearly effortlessly - by more popular\nmeans. Such is far from the case, however. The fact that kinetic theory remains\nvery much in charge is best appreciated through the physics of a quantum point\ncontact. While discretization of its conductance is viewed as the exclusive\nresult of coherent, single-electron-wave transmission, this does not begin to\naddress the paramount feature of all metallic conduction: dissipation. A\nperfect quantum point contact still has finite resistance, so its ballistic\ncarriers must dissipate the energy gained from the applied field. How do they\nmanage that? The key is in standard many-body quantum theory, and its\nconservation principles.",
        "positive": "Ar+-sputtered Ge (001) surface nanostructuring at high implant\n  temperature: Ion sputtering induced nanoscale pattern formation on Ge (001) surface by 500\neV Ar+ bombardment has been investigated for a wide range of ion incidence\nangles at temperature of 300 deg.C. A fourfold symmetric topography forms in\nthe angular regime 0 - 65 deg. Above 65 deg, they show a remarkable transition\ninto highly regular one-dimensional (1D) asymmetric pattern, known as\nperpendicular mode ripples. In order to understand growth dynamics of both kind\nof patterns, we have investigated their temporal evolution as a function of ion\nfluence in a wide range from 1*10^{17} to 1*10^{20} ions cm-2. In addition, we\nstudy the effect of substrate rotation on Ge surface morphology in whole\nangular range. The four-fold symmetric patterns effect does not found to alter\ntheir symmetry, while the ripples degenerate into hole structure with a weak\nfourfold symmetric pattern. The origin of square topographies and their\nsymmetry independency on ion incident angle in the range 0 to 65 deg can be\nattributed to the growth process due to biased diffusion of vacancies arising\nfrom Ehrlich-Schwoebel barrier. Whereas, the ripple formation at grazing\nincidence angles indicates the dominance of curvature dependent surface\ninstability induced by the incident ion direction."
    },
    {
        "anchor": "A nu=2/5 Paired Wavefunction: We construct a wavefunction, generalizing the well known Moore-Read Pfaffian,\nthat describes spinless electrons at filling fraction nu=2/5 (or bosons at\nfilling fraction nu=2/3) as the ground state of a very simple three body\npotential. We find, analogous to the Pfaffian, that when quasiholes are added\nthere is a ground state degeneracy which can be identified as zero-modes of the\nquasiholes. The zero-modes are identified as having semionic statistics. We\nwrite this wavefunction as a correlator of the Virasoro minimal model conformal\nfield theory M(5,3). Since this model is non-unitary, we conclude that this\nwavefunction is a quantum critical state. Nonetheless, we find that the\noverlaps of this wavefunction with exact diagonalizations in the lowest and\nfirst excited Landau level are very high, suggesting that this wavefunction may\nhave experimental relevance for some transition that may occur in that regime.",
        "positive": "Interactions and Disorder in Multi-Channel Quantum Wires: Recent experiments have revealed that the temperature dependence of the\nconductance of quasi-ballistic quantum wires bears clear features of the\nLuttinger-liquid state. In this paper, the conductance of an N-channel quantum\nwire is calculated within the model of N coupled Luttinger liquids and under\nthe assumption of weak disorder. It is shown that as the number of channels\nincreases, a crossover from the Luttinger-liquid to the Fermi-liquid behavior\noccurs. This crossover manifests itself in the 1/N decrease of the scaling\nexponent of the temperature dependence. An exact expression for the scaling\nexponent for the case of N coupled Luttinger chains is obtained, and the large\nN limit is studied for the case of a quantum wire. The case of N=2 for\nelectrons with spin is analyzed in detail, and a qualitative agreement with the\nexperiment is achieved."
    },
    {
        "anchor": "Spin Currents in Metallic Nanostructures; Explicit Calculations: In ultrathin ferromagnets deposited on metallic substrates, excitation of\nprecessional motion of the spins produces a spin current in the substrate that\ntransports angular momentum out of the film. This phenomenon is referred to as\nspin pumping, and is a source of damping of the spin motion. Spin pumping\nenters importantly in the description of spin dynamics in other nanoscale and\nsubnanoscale systems as well. In this paper, we present an approach based on\nthe Kubo formalism that allows the explicit calculation of this spin current\nand its spatial variation. We use the formalism to explore features of the spin\ncurrent generated by spin motions in a simple model system.",
        "positive": "Tunable Electron Interactions and Fractional Quantum Hall States in\n  Graphene: The recent discovery of fractional quantum Hall states in graphene raises the\nquestion of whether the physics of graphene and its bilayer offers any\nadvantages over GaAs-based materials in exploring strongly-correlated states of\ntwo-dimensional electrons. Here we propose a method to continuously tune the\neffective electron interactions in graphene and its bilayer by the dielectric\nenvironment of the sample. Using this method, the charge gaps of prominent FQH\nstates, including \\nu=1/3 or \\nu=5/2 states, can be increased several times, or\nreduced all the way to zero. The tunability of the interactions can be used to\nrealize and stabilize various strongly correlated phases in the FQH regime, and\nto explore the transitions between them."
    },
    {
        "anchor": "Electrical signature of individual magnetic skyrmions in multilayered\n  systems: Magnetic skyrmions are topologically protected whirling spin textures that\ncan be stabilized in magnetic materials in which a chiral interaction is\npresent. Their limited size together with their robustness against the external\nperturbations promote them as the ultimate magnetic storage bit in a novel\ngeneration of memory and logic devices. Despite many examples of the signature\nof magnetic skyrmions in the electrical signal, only low temperature\nmeasurements, mainly in magnetic materials with B20 crystal structure, have\ndemonstrated the skyrmions contribution to the electrical transport properties.\nUsing the combination of Magnetic Force Microscopy (MFM) and Hall resistivity\nmeasurements, we demonstrate the electrical detection of sub-100 nm skyrmions\nin multilayered thin film at room temperature (RT). We furthermore analyse the\nroom temperature Hall signal of a single skyrmion which contribution is mainly\ndominated by anomalous Hall effect.",
        "positive": "The addition spectrum of interacting electrons: Parametric dependence: The addition spectrum of a disordered stadium is studied for up to 120\nelectrons using the self consistent Hartree-Fock approximation for different\nvalues of the dimensionless conductance and in the presence and absence of a\nneutralizing background. In all cases a Gaussian distribution of the addition\nspectrum is reached for $r_s \\leq 1$. An empirical scaling for the distribution\nwidth in the presence of a neutralizing background is tested and seems to\ndescribe rather well its dependence on the dimensionless conductance."
    },
    {
        "anchor": "Topological delocalization of two-dimensional massless Dirac fermions: The beta function of a two-dimensional massless Dirac Hamiltonian subject to\na random scalar potential, which e.g., underlies the theoretical description of\ngraphene, is computed numerically. Although it belongs to, from a symmetry\nstandpoint, the two-dimensional symplectic class, the beta function\nmonotonically increases with decreasing $g$. We also provide an argument based\non the spectral flows under twisting boundary conditions, which shows that none\nof states of the massless Dirac Hamiltonian can be localized.",
        "positive": "Theory of single spin inelastic tunneling spectroscopy: Recent work shows that inelastic electron scanning tunneling microscope (STM)\nprobes the elementary spin excitations of a single and a few magnetic atoms in\na thin insulating layer. Here I show that this new type of spectroscopy is\ndescribed using a phenomenological spin-assisted tunneling Hamiltonian. Within\nthis formalism, the inelastic $dI/dV$ lineshape is related to the spin spectral\nweight of the probed magnetic atom. This accounts for the spin selection rules\nobserved experimentally. The theory agrees well with existing STM experiments\nfor single Fe and Mn atoms as well as linear chains a few Mn atoms. The\nmagnetic anisotropy in the inelastic $dI/dV$ and the marked odd-even $N$\neffects are accounted for by the theory."
    },
    {
        "anchor": "Moir\u00e9 excitons: from programmable quantum emitter arrays to spin-orbit\n  coupled artificial lattices: Highly uniform and ordered nanodot arrays are crucial for high performance\nquantum optoelectronics including new semiconductor lasers and single photon\nemitters, and for synthesizing artificial lattices of interacting\nquasiparticles towards quantum information processing and simulation of\nmany-body physics. Van der Waals heterostructures of 2D semiconductors are\nnaturally endowed with an ordered nanoscale landscape, i.e. the moir\\'e pattern\nthat laterally modulates electronic and topographic structures. Here we find\nthese moir\\'e effects realize superstructures of nanodot confinements for\nlong-lived interlayer excitons, which can be either electrically or strain\ntuned from perfect arrays of quantum emitters to excitonic superlattices with\ngiant spin-orbit coupling (SOC). Besides the wide range tuning of emission\nwavelength, the electric field can also invert the spin optical selection rule\nof the emitter arrays. This unprecedented control arises from the gauge\nstructure imprinted on exciton wavefunctions by the moir\\'e, which underlies\nthe SOC when hopping couples nanodots into superlattices. We show that the\nmoir\\'e hosts complex-hopping honeycomb superlattices, where exciton bands\nfeature a Dirac node and two Weyl nodes, connected by spin-momentum locked\ntopological edge modes.",
        "positive": "Thermal insulation and heat guiding using nanopatterned MoS2: In the modern electronics overheating is one of the major reasons for device\nfailure. Overheating causes irreversible damage to circuit components and can\nalso lead to fire, explosions, and injuries. Accordingly, in the advent of 2D\nmaterial-based electronics, an understanding of their thermal properties in\naddition to their electric ones is crucial to enable efficient transfer of\nexcess heat away from the electronic components. In this work we propose\nstructures based on free-standing, few-layer, nanopatterned MoS2 that insulate\nand guide heat in the in-plane direction. We arrive at these designs via a\nthorough study of the in-plane thermal conductivity as a function of thickness,\nporosity, and temperature in both pristine and nanopatterned MoS2 membranes.\nTwo-laser Raman thermometry was employed to measure the thermal conductivities\nof a set of free-standing MoS2 flakes with diameters greater than 20 um and\nthicknesses from 5 to 40 nm, resulting in values from 30 to 85 W/mK,\nrespectively. After nanopatterning a square lattice of 100-nm diameter holes\nwith a focused ion beam we have obtained a greater than 10-fold reduction of\nthe thermal conductivities for the period of 500 nm and values below 1 W/mK for\nthe period of 300 nm. The results were supported by equilibrium molecular\ndynamic simulations for both pristine and nanopatterned MoS2. The selective\npatterning of certain areas results in extremely large difference in thermal\nconductivities within the same material. Exploitation of this effect enabled\nfor the first time thermal insulation and heat guiding in the few-layer MoS2.\nThe patterned regions act as high thermal resistors: we obtained a thermal\nresistance of 4x10-6 m2K/W with only four patterned lattice periods of 300 nm,\nhighlighting the significant potential of MoS2 for thermal management\napplications."
    },
    {
        "anchor": "Second-Order Topological Insulator in van der Waals Heterostructures of\n  CoBr$_2$/Pt$_2$HgSe$_3$/CoBr$_2$: Second-order topological insulator, which has (d-2)-dimensional topological\nhinge or corner states, has been observed in three-dimensional materials, but\nhas yet not been observed in two-dimensional system. In this Letter, we\ntheoretically propose the realization of second-order topological insulator in\nthe van der Waals heterostructure of CoBr$_2$/Pt$_2$HgSe$_3$/CoBr$_2$.\nPt$_2$HgSe$_3$ is a large gap $\\mathbb{Z}_2$ topological insulator. With\nin-plane exchange field from neighboring CoBr$_2$, a large band gap above 70\nmeV opens up at the edge. The corner states, which are robust against edge\ndisorders and irregular shapes, are confirmed in the nanoflake. We further show\nthat the second-order topological states can also be realized in the\nheterostructure of jacutingaite family $\\mathbb{Z}_2$ topological insulators.\nWe believe that our work will be beneficial for the experimental realization of\nsecond-order topological insulators in van der Waals layered materials.",
        "positive": "Micro-Hall Magnetometry Studies of Thermally Assisted and Pure Quantum\n  Tunneling in Single Molecule Magnet Mn12-Acetate: We have studied the crossover between thermally assisted and pure quantum\ntunneling in single crystals of high spin (S=10) uniaxial single molecule\nmagnet Mn12-acetate using micro-Hall effect magnetometry. Magnetic hysteresis\nexperiments have been used toinvestigate the energy levels that determine the\nmagnetization reversal as a function of magnetic field and temperature. These\nexperiments demonstrate that the crossover occurs in a narrow (~0.1 K) or broad\n(~1 K) temperature interval depending on the magnitude and direction of the\napplied field. For low external fields applied parallel to the easy axis, the\nenergy levels that dominate the tunneling shift abruptly with temperature. In\nthe presence of a transverse field and/or large longitudinal field these energy\nlevels change with temperature more gradually. A comparison of our experimental\nresults with model calculations of this crossover suggest that there are\nadditional mechanisms that enhance the tunneling rate of low lying energy\nlevels and broaden the crossover for small transverse fields."
    },
    {
        "anchor": "Excitation Gap of Fractal Quantum Hall States in Graphene: In the presence of a magnetic field and an external periodic potential, the\nLandau level spectrum of a two-dimensional electron gas exhibits a fractal\npattern in the energy spectrum which is described as the Hofstadter's\nbutterfly. In this work, we develop a Hartree-Fock theory to deal with the\nelectron-electron interaction in the Hofstadter's butterfly state in a\nfinite-size graphene with periodic boundary conditions, in which we include\nboth spin and valley degrees of freedom. We then treat the butterfly state as\nan electron crystal so that we could obtain the order parameters of the crystal\nin the momentum space and also in an infinite sample. The excitation gaps\nobtained in the infinite sample is comparable to those in the finite-size\nstudy, and agree with a recent experimental observation.",
        "positive": "Absorption of Transverse Spin Current in Ferromagnetic NiCu: Dominance\n  of Bulk Dephasing over Spin-Flip Scattering: In ferromagnetic metals, transverse spin currents are thought to be absorbed\nvia dephasing -- i.e., destructive interference of spins precessing about the\nstrong exchange field. Yet, due to the ultrashort coherence length of\n$\\approx$1 nm in typical ferromagnetic thin films, it is difficult to\ndistinguish dephasing in the bulk from spin-flip scattering at the interface.\nHere, to assess which mechanism dominates, we examine transverse spin-current\nabsorption in ferromagnetic NiCu alloy films with reduced exchange fields. We\nobserve that the coherence length increases with decreasing Curie temperature,\nas weaker dephasing in the film bulk slows down spin absorption. Moreover,\nnonmagnetic Cu impurities do not diminish the efficiency of spin-transfer\ntorque from the absorbed spin current. Our findings affirm that transverse spin\ncurrent is predominantly absorbed by dephasing inside the nanometer-thick\nferromagnetic metals, even with high impurity contents."
    },
    {
        "anchor": "Merged Four Dirac Points at the Critical Interlayer Distance in\n  Commensurately Twisted Bilayer Graphene: the Origin of the Zero Velocity: We study the commensurately-tilted bilayer graphene in the tight-binding\nmodel with changing the interlayer distance, which can be tuned by pressure. We\nfind that at the commensurately-tilted bilayer graphene with moderate rotating\nangles, when the energy gap at K point is not negligible, the other Dirac\npoints within the upper two bands move along the $\\Gamma$-K-M line in the\nbilayer Brillouzone, when the interlayer distance is changed. The velocity at K\npoint becomes zero due to the merging of the four Dirac points within upper two\nbands. This mechanism of zero velocity at K point is expected to be the origin\nof the magic angle with flat band at ambient pressure, at which the upper two\nbands are almost degenerate and the band gap at K can be neglected.",
        "positive": "Theoretical Perspectives on Spintronics and Spin-Polarized Transport: Selected problems of fundamental importance for spintronics and\nspin-polarized transport are reviewed, some of them with a special emphasis on\ntheir applications in quantum computing and coherent control of quantum\ndynamics. The role of the solid-state environment in the decoherence of\nelectron spins is discussed. In particular, the limiting effect of the\nspin-orbit interaction on spin relaxation of conduction electrons is carefully\nexamined in the light of recent theoretical and experimental progress. Most of\nthe proposed spintronic devices involve spin-polarized transport across\ninterfaces in various hybrid structures. The specific example discussed here,\nof a magnetic semiconductor/superconductor interface, displays many intricacies\nwhich a complex spin-dependent interface introduces in the spin-polarized\ntransport. It is proposed that pairs of entangled electrons in a superconductor\n(Cooper pairs) can be transfered to a non-superconducting region, and\nconsequently separated for a transport study of the spin entanglement. Several\nimportant theoretical proposals for quantum computing are based on electronic\nand nuclear spin entanglement in a solid. Physical requirements for these\nproposals to be useful are discussed and some alternative views are presented.\nFinally, a recent discovery of optical control of nuclear spins in\nsemiconductors is reviewed and placed in the context of a long-standing search\nfor electronic control of nuclear dynamics."
    },
    {
        "anchor": "Exact analytic formula for conductance predicting a tunable\n  Sommerfeld-Arrhenius thermal transition within a single-step tunneling\n  mechanism in molecular junctions subject to mechanical stretching: We show that the conductance $G$ of molecular tunnel junctions wherein the\ncharge transport is dominated by a single energy level can be expressed in\nclosed analytic form which is exact and valid at arbitrary temperature $T$ and\nmodel parameter values. On this basis, we show that the single-step tunneling\nmechanism is compatible with a continuous thermal transition from a weakly\n$T$-dependent $G$ at low $T$ (Sommerfeld regime) to a nearly exponential\n$1/T$-dependent $G$ at high $T$ (Arrhenius-like regime). We predict that this\nSommerfeld-Arrhenius transition can be observed in real molecular junctions %\n(e.g., based on perylene diimide) and can be continuously tuned, e.g., via\nmechanical stretching.",
        "positive": "Thermometry based on Coulomb-coupled quantum dots: A theoretical proposal that Coulomb-coupled quantum dots can be used as\nquantum probes to determine the temperature of a sample (i.e., an electronic\nreservoir) is proposed. Through the regulation of the positive or negative\nvoltage bias in the thermometer, we are able to judge whether the temperature\nof the sample is higher or lower than that of the reference heat reservoir in\nthe measure environment and to determine the precise temperature of the sample\nby using a particularly simple temperature-voltage bias relationship in the\nreversible condition. One outstanding characteristic of the thermometer is that\nwhen the sample is at low temperatures, a small temperature change will lead to\na large voltage bias change. It means that the proposed thermometer has a high\nsensitivity when low-temperature samples are measured."
    },
    {
        "anchor": "Quantum anomalous Hall insulator of composite fermions in twisted\n  bilayer graphene: Abstract We theoretically study the realization of quantum anomalous Hall\ninsulator (QAHI) of composite fermions (CFs) in the twisted bilayer graphene\n(TBG) system. We show that the moir\\'e pattern in TBG is not only able to\nprovide a commensurate moir\\'e superlattice, but also a tunable effective\nperiodic potential necessary for the realization, without the need of imposing\nan additional superstructure as in the conventional GaAs system. These make the\nTBG an ideal platform for realizing the QAHI of CFs. We establish the phase\ndiagram with respect to tunable experimental parameters based on the Dirac CF\ntheory. We find that the topological property of the system depends critically\non the orbital magnetic susceptibility of CFs, which is not specified in the\npristine Dirac CF theory. The experimental realization of QAHI of CFs would be\nhelpful for unveiling the magnetic property of CFs and clarifying the issue.",
        "positive": "Super-fermion representation of the Lindblad master equation for the\n  electron transport problem: We discuss the use of super-fermion formalism to represent and solve quantum\nkinetic equations for the electron transport problem. Starting with the\nLindblad master equation for the molecule connected to two metal electrodes, we\nconvert the problem of finding the nonequilibrium steady state to the many-body\nproblem with non-Hermitian Liouvillian in super-Fock space. We transform the\nLiouvillian to the normal ordered form, introduce nonequilibrium quasiparticles\nby a set of canonical nonunitary transformations and develop general many-body\ntheory for the electron transport through the interacting region. The approach\nis applied to the electron transport through a single level. We consider a\nminimal basis hydrogen atom attached to two metal leads in Coulomb blockade\nregime (out of equilibrium Anderson model) within the nonequilibrium\nHartree-Fock approximation as an example of the system with electron\ninteraction. Our approach agrees with exact results given by the Landauer\ntheory for the considered models."
    },
    {
        "anchor": "Ferromagnetic resonance of a two-dimensional array of nanomagnets:\n  Effects of surface anisotropy and dipolar interactions: We develop an analytical approach for studying the FMR frequency shift due to\ndipolar interactions and surface effects in two-dimensional arrays of\nnanomagnets with (effective) uniaxial anisotropy along the magnetic field. For\nthis we build a general formalism on the basis of perturbation theory that\napplies to dilute assemblies but which goes beyond the point-dipole\napproximation as it takes account of the size and shape of the nano-elements,\nin addition to their separation and spatial arrangement. The contribution to\nthe frequency shift due to the shape and size of the nano-elements has been\nobtained in terms of their aspect ratio, their separation and the lattice\ngeometry. We have also varied the size of the array itself and compared the\nresults with a semi-analytical model and reached an agreement that improves as\nthe size of the array increases. We find that the red-shift of the\nferromagnetic resonance due to dipolar interactions decreases for smaller\narrays. Surface effects may induce either a blue-shift or a red-shift of the\nFMR frequency, depending on the crystal and magnetic properties of the\nnano-elements themselves. In particular, some configurations of the\nnano-elements assemblies may lead to a full compensation between surface\neffects and dipole interactions.",
        "positive": "Orbital effect of magnetic field on the Majorana phase diagram: Studies of Majorana bound states in semiconducting nanowires frequently\nneglect the orbital effect of magnetic field. Systematically studying its role\nleads us to several conclusions for designing Majoranas in this system.\nSpecifically, we show that for experimentally relevant parameter values orbital\neffect of magnetic field has a stronger impact on the dispersion relation than\nthe Zeeman effect. While Majoranas do not require a presence of only one\ndispersion subband, we observe that the size of the Majoranas becomes\nunpractically large, and the band gap unpractically small when more than one\nsubband is filled. Since the orbital effect of magnetic field breaks several\nsymmetries of the Hamiltonian, it leads to the appearance of large regions in\nparameter space with no band gap whenever the magnetic field is not aligned\nwith the wire axis. The reflection symmetry of the Hamiltonian with respect to\nthe plane perpendicular to the wire axis guarantees that the wire stays gapped\nin the topologically nontrivial region as long as the field is aligned with the\nwire."
    },
    {
        "anchor": "Fermi liquid to Luttinger liquid transition at the edge of a\n  two-dimensional electron gas: We present experimental results on the tunneling into the edge of a two\ndimensional electron gas (2DEG) obtained with a GaAs/AlGaAs cleaved edge\novergrown structure in a strong perpendicular magnetic field. While the 2DEG\nexhibits typical fractional quantum Hall features of a very high mobility\nsample, we observe the onset of a non-linear current-voltage characteristic in\nthe vicinity of nu=1. For filling factor nu<1 the system is consistent with a\nnon-Fermi liquid behavior, such as a Luttinger liquid, whereas for nu>1 we\nobserve an Ohmic tunneling resistance between the edge and a three dimensional\ncontact, typical for a Fermi liquid. Hence, at the edge, there is a transition\nfrom a Luttinger liquid to a Fermi liquid. Finally, we show that the Luttinger\nliquid exponent at a given filling factor is not universal but depends on\nsample parameters.",
        "positive": "Diffusion Limited Aggregation with modified local rules: Results from a modified Diffusion Limited Aggregation (DLA) model are\npresented. The modifications of the classical DLA model are in the attachment\nto the cluster rules and in the scheme of particle generation/killing. In the\nclassical DLA model if a particle reaches the growing cluster it sticks to it\nimmediately and irreversibly and then the next particle is released. We will\nabandon this original prerequisite, and by changing the sticking probability to\nthe cluster we will change the diffusion regime towards more kinetic one. For a\ngrowing cluster consisting of only one type of particles this variation in the\nsticking probability is (more or less) a rude violation of the hypothesis for\ndiffusion limitation in the DLA model. Since in a lot of experiments different\ntypes of particles are used with different sticking probabilities (e.g.\ndifferent regimes of attachment), we develop a modified DLA model with two\ntypes of particles. The second modification we introduce at that point is a\nscheme for particle generation/killing we call \"second chance\" - when a\nparticle is killed after reaching a given limiting distance from the cluster,\nit is killed and then returned to the point it was originally generated. Thus\nthe model is capable to produce a great variety of growing patterns (fractals,\nspirals) by changing only a single parameter and we are able to construct a\nmorphological diagram of our generalized DLA model with two different types of\nparticles."
    },
    {
        "anchor": "Anomalous non-Hermitian skin effect: the topological inequivalence of\n  skin modes versus point gap: Non-Hermitian skin effect, the localization of an extensive number of\neigenstates at the ends of the system, has greatly expanded the frontier of\nphysical laws. It has long been believed that the present of skin modes is\nequivalent to the topologically nontrivial point gap of complex eigenvalues\nunder periodic boundary conditions, and vice versa. However, we find that this\nconcomitance can be broken, i.e., the skin modes can be present or absent\nwhereas the point gap is topologically trivial or nontrivial, respectively,\nnamed anomalous non-Hermitian skin effect. This anomalous phenomenon arises\nwhen the unidirectional hopping amplitudes leading to the decoupling-like\nbehaviors among subsystems are emergence. The emergence of the anomalous\nnon-Hermitian skin effect is accompanied by the mutations of the open boundary\nenergy spectrum, whose structure exhibits the multifold exceptional point and\ncan not be recovered by continuum bands. Moreover, an experimental setup using\ncircuits is proposed to simulate this novel quantum effect. Our results reveal\nthe topologically inequivalent between skin modes and point gap. This new\neffect not only can give a deeper understanding of non-Bloch theory and the\ncritical phenomenon in non-Hermitian systems, but may also inspire new\napplications such as in the sensors field.",
        "positive": "Statics and Dynamics of Skyrmions Interacting with Pinning: A Review: Magnetic skyrmions are topologically stable nanoscale particle-like objects\nthat were discovered in 2009. Since that time, intense research interest has\nled to the identification of numerous compounds that support skyrmions over a\nrange of conditions spanning cryogenic to room temperatures. Skyrmions can be\nset into motion under various types of driving, and the combination of their\nsize, stability, and dynamics makes them ideal candidates for numerous\napplications. Skyrmions represent a new class of system in which the energy\nscales of the skyrmion-skyrmion interactions, sample disorder, temperature, and\ndrive can compete. A growing body of work indicates that the static and dynamic\nstates of skyrmions can be influenced strongly by pinning or disorder in the\nsample; thus, an understanding of such effects is essential for the eventual\nuse of skyrmions in applications. In this article we review the current state\nof knowledge regarding individual skyrmions and skyrmion assemblies interacting\nwith quenched disorder or pinning. We outline the microscopic mechanisms for\nskyrmion pinning, including the repulsive and attractive interactions that can\narise from impurities, grain boundaries, or nanostructures. This is followed by\ndescriptions of depinning phenomena, sliding states over disorder, the effect\nof pinning on the skyrmion Hall angle, the competition between thermal and\npinning effects, the control of skyrmion motion using ordered potential\nlandscapes such as one- or two-dimensional periodic asymmetric substrates, the\ncreation of skyrmion diodes, and skyrmion ratchet effects. We highlight the\ndistinctions arising from internal modes and the strong gyroscopic or Magnus\nforces that cause the dynamical states of skyrmions to differ from those of\nother systems with pinning. We also discuss future directions and open\nquestions related to the pinning and dynamics in skyrmion systems."
    },
    {
        "anchor": "Composition law for the Cole-Cole relaxation and ensuing evolution\n  equations: Physically natural assumption says that the any relaxation process taking\nplace in the time interval $[t_{0},t_{2}]$, $t_{2} > t_{0}\\ge 0$ may be\nrepresented as a composition of processes taking place during time intervals\n$[t_{0}, t_{1}]$ and $[t_{1},t_{2}]$ where $t_{1}$ is an arbitrary instant of\ntime such that $t_{0} \\leq t_{1} \\leq t_{2}$. For the Debye relaxation such a\ncomposition is realized by usual multiplication which claim is not valid any\nlonger for more advanced models of relaxation processes. We investigate the\ncomposition law required to be satisfied by the Cole-Cole relaxation and find\nits explicit form given by an integro-differential relation playing the role of\nthe time evolution equation. The latter leads to differential equations\ninvolving fractional derivatives, either of the Caputo or the Riemann-Liouville\nsenses, which are equivalent to the special case of the fractional\nFokker-Planck equation satisfied by the Mittag-Leffler function known to\ndescribe the Cole-Cole relaxation in the time domain.",
        "positive": "Stochastic dynamics for a single vibrational mode in molecular junctions: We propose a very accurate computational scheme for the dynamics of a\nclassical oscillator coupled to a molecular junction driven by a finite bias,\nincluding the finite mass effect. We focus on two minimal models for the\nmolecular junction: Anderson-Holstein (AH) and two-site Su-Schrieffer-Heeger\n(SSH) models. As concerns the oscillator dynamics, we are able to recover a\nLangevin equation confirming what found by other authors with different\napproaches and assessing that quantum effects come from the electronic\nsubsystem only. Solving numerically the stochastic equation, we study the\nposition and velocity distribution probabilities of the oscillator and the\nelectronic transport properties at arbitrary values of electron-oscillator\ninteraction, gate and bias voltages. The range of validity of the adiabatic\napproximation is established in a systematic way by analyzing the behaviour of\nthe kinetic energy of the oscillator. Due to the dynamical fluctuations, at\nintermediate bias voltages, the velocity distributions deviate from a gaussian\nshape and the average kinetic energy shows a non monotonic behaviour. In this\nsame regime of parameters, the dynamical effects favour the conduction far from\nelectronic resonances where small currents are observed in the infinite mass\napproximation. These effects are enhanced in the two-site SSH model due to the\npresence of the intermolecular hopping t. Remarkably, for sufficiently large\nhopping with respect to tunneling on the molecule, small interaction strengths\nand at intermediate bias (non gaussian regime), we point out a correspondence\nbetween the minima of the kinetic energy and the maxima of the dynamical\nconductance."
    },
    {
        "anchor": "Quantized Thermoelectric Hall Effect Induces Giant Power Factor in a\n  Topological Semimetal: Thermoelectrics are promising by directly generating electricity from waste\nheat. However, (sub-)room-temperature thermoelectrics have been a long-standing\nchallenge due to vanishing electronic entropy at low temperatures. Topological\nmaterials offer a new avenue for energy harvesting applications. Recent\ntheories predicted that topological semimetals at the quantum limit can lead to\na large, non-saturating thermopower and a quantized thermoelectric Hall\nconductivity approaching a universal value. Here, we experimentally demonstrate\nthe non-saturating thermopower and quantized thermoelectric Hall effect in the\ntopological Weyl semimetal (WSM) tantalum phosphide (TaP). An ultrahigh\nlongitudinal thermopower Sxx= 1.1x10^3 muV/K and giant power factor ~525\nmuW/cm/K^2 are observed at ~40K, which is largely attributed to the quantized\nthermoelectric Hall effect. Our work highlights the unique quantized\nthermoelectric Hall effect realized in a WSM toward low-temperature energy\nharvesting applications.",
        "positive": "Topological Andreev bands in three-terminal Josephson junctions: We study the emergent band topology of subgap Andreev bound states in the\nthree-terminal Josephson junctions. We scrutinize the symmetry constraints of\nthe scattering matrix in the normal region connecting superconducting leads\nthat enable the topological nodal points in the spectrum of Andreev states.\nWhen the scattering matrix possesses time-reversal symmetry, the gap closing\noccurs at special stationary points that are topologically trivial as they\ncarry vanishing Berry fluxes. In contrast, for the time-reversal broken case we\nfind topological monopoles of the Berry curvature and corresponding phase\ntransition between states with different Chern numbers. The latter is\ncontrolled by the structure of the scattering matrix that can be tuned by a\nmagnetic flux piercing through the junction area in a three-terminal geometry.\nThe topological regime of the system can be identified by nonlocal conductance\nquantization that we compute explicitly for a particular parametrization of the\nscattering matrix in the case where each reservoir is connected by a single\nchannel."
    },
    {
        "anchor": "Graphene: A Pseudochiral Fermi Liquid: Doped graphene sheets are pseudochiral two-dimensional Fermi liquids with\nabnormal electron-electron interaction physics. We address graphene's Fermi\nliquid properties quantitatively using a microscopic random-phase-approximation\ntheory and comment on the importance of using exchange-correlation potentials\nbased on the properties of a chiral two-dimensional electron gas in\ndensity-functional-theory applications to graphene nanostructures.",
        "positive": "Synchronization of spin-torque driven nanooscillators for point contacts\n  on a quasi-1D nanowire: Micromagnetic simulations: In this paper we present detailed numerical simulation studies on the\nsynchronization of two spin-torque nanooscillators (STNO) in the quasi-1D\ngeometry: magnetization oscillations are induced in a thin NiFe nanostripe by a\nspin polarized current injected via square-shaped CoFe nanomagnets on the top\nof this stripe. In a sufficiently large out-of-plane field, a propagating\noscillation mode appears in such a system. Due to the absence of the\ngeometrically caused wave decay in 1D systems, this mode is expected to enable\na long-distance synchronization between STNOs. Indeed, our simulations predict\nthat synchronization of two STNOs on a nanowire is possible up to the\nintercontact distance 3 mkm (for the nanowire width 50 nm). However, we have\nalso found several qualitatively new features of the synchronization behaviour\nfor this system, which make the achievement of a stable synchronization in this\ngeometry to a highly non-trivial task. In particular, there exist a minimal\ndistance between the nanocontacts, below which a synchronization of STNOs can\nnot be achieved. Further, when the current value in the first contact is kept\nconstant, the amplitude of synchronized oscillations depends non-monotonously\non the current value in the second contact. Finally, for one and the same\ncurrents values through the contacts there might exist several synchronized\nstates (with different frequencies), depending on the initial conditions."
    },
    {
        "anchor": "Thermoelectric properties of the bismuth telluride nanowires in the\n  constant-relaxation-time approximation: Electronic structure of bismuth telluride nanowires with the growth\ndirections [110] and [015] is studied in the framework of anisotropic effective\nmass method using the parabolic band approximation. The components of the\nelectron and hole effective mass tensor for six valleys are calculated for both\ngrowth directions. For a square nanowire, in the temperature range from 77 K to\n500 K, the dependence of the Seebeck coefficient, the electron thermal and\nelectrical conductivity as well as the figure of merit ZT on the nanowire\nthickness and on the excess hole concentration are investigated in the\nconstant-relaxation-time approximation. The carrier confinement is shown to\nplay essential role for square nanowires with thickness less than 30 nm. The\nconfinement decreases both the carrier concentration and the thermal\nconductivity but increases the maximum value of Seebeck coefficient in contrast\nto the excess holes (impurities). The confinement effect is stronger for the\ndirection [015] than for the direction [110] due to the carrier mass difference\nfor these directions. The carrier confinement increases maximum value of ZT and\nshifts it towards high temperatures. For the p-type bismuth telluride nanowires\nwith growth direction [110], the maximum value of the figure of merit is equal\nto 1.3, 1.6, and 2.8, correspondingly, at temperatures 310 K, 390 K, 480 K and\nthe nanowire thicknesses 30 nm, 15 nm, and 7 nm. At the room temperature, the\nfigure of merit equals 1.2, 1.3, and 1.7, respectively.",
        "positive": "Modeling inelastic phonon scattering in atomic- and molecular-wire\n  junctions: Computationally inexpensive approximations describing electron-phonon\nscattering in molecular-scale conductors are derived from the non-equilibrium\nGreen's function method. The accuracy is demonstrated with a first principles\ncalculation on an atomic gold wire. Quantitative agreement between the full\nnon-equilibrium Green's function calculation and the newly derived expressions\nis obtained while simplifying the computational burden by several orders of\nmagnitude. In addition, analytical models provide intuitive understanding of\nthe conductance including non-equilibrium heating and provide a convenient way\nof parameterizing the physics. This is exemplified by fitting the expressions\nto the experimentally observed conductances through both an atomic gold wire\nand a hydrogen molecule."
    },
    {
        "anchor": "Robustness of the Spin-Chern number: The Spin-Chern ($C_s$) was originally introduced on finite samples by\nimposing spin boundary conditions at the edges. This definition lead to\nconfusing and contradictory statements. On one hand the original paper by Sheng\nand collaborators revealed robust properties of $C_s$ against disorder and\ncertain deformations of the model and, on the other hand, several people\npointed out that $C_s$ can change sign under special deformations that keep the\nbulk Hamiltonian gap open. Because of the later findings, the Spin-Chern number\nwas dismissed as a true bulk topological invariant and now is viewed as\nsomething that describes the edge where the spin boundary conditions are\nimposed. In this paper, we define the Spin-Chern number directly in the\nthermodynamic limit, without using any boundary conditions. We demonstrate its\nquantization in the presence of strong disorder and we argue that $C_s$ is a\ntrue bulk topological invariant whose robustness against disorder and smooth\ndeformations of the Hamiltonian have important physical consequences. The\nproperties of the Spin-Chern number remain valid even when the time reversal\ninvariance is broken.",
        "positive": "Fabrication and characterisation of ambipolar devices on an undoped\n  AlGaAs/GaAs heterostructure: We have fabricated AlGaAs/GaAs heterostructure devices in which the\nconduction channel can be populated with either electrons or holes simply by\nchanging the polarity of a gate bias. The heterostructures are entirely\nundoped, and carriers are instead induced electrostatically. We use these\ndevices to perform a direct comparison of the scattering mechanisms of\ntwo-dimensional (2D) electrons\n($\\mu_\\textrm{peak}=4\\times10^6\\textrm{cm}^2/\\textrm{Vs}$) and holes\n($\\mu_\\textrm{peak}=0.8\\times10^6\\textrm{cm}^2/\\textrm{Vs}$) in the same\nconduction channel with nominally identical disorder potentials. We find\nsignificant discrepancies between electron and hole scattering, with the hole\nmobility being considerably lower than expected from simple theory."
    },
    {
        "anchor": "Reply to Comment on \"Berry phase correction to electron density of\n  states in solids\": The Comment by Duval et al. [PRL 96, 099701 (2006)] addresses an important,\nbut not the main, result of our Letter [PRL 95, 137204 (2005)]. It does not\ncontradict our results in substance, and the only objection is really on the\nstyle of approach.",
        "positive": "Probing fractional topological insulators with magnetic edge\n  perturbations: We discuss detection strategies for fractional topological insulators (FTIs)\nrealizing time-reversal invariant analogues of fractional quantum Hall systems\nin the Laughlin universality class. Focusing on transport measurements, we\nstudy the effect of magnetic perturbations on the edge modes. We find that the\nmodes show unexpected robustness against magnetic backscattering for moderate\ncouplings and edge interactions, allowing for various phase transitions\nsignaling the FTI phase. We also describe protocols for extracting the\nuniversal integer m characterizing the phase and the edge interaction parameter\nfrom the conductance of setups with magnets and a quantum point contact."
    },
    {
        "anchor": "Theoretical basis for the unification of the integer and the fractional\n  quantum Hall effects: This paper intends to provide a theoretical basis for the unification of the\ninteger and the fractional quantum Hall effects. Guided by concepts and\ntheories of quantum mechanics and with the solution of the Pauli equation in a\nmagnetic field under the symmetric gauge, wave functions, energy levels of\nsingle electrons, and the expectation value of electron's spatial scope are\npresented. After the quotation of non-interaction dilute gas system, the\nproduct of single electron's wave functions is used to construct wave functions\nof the N electron gas system in magnetic field. Then the expectation value of\nthe system's motion area and the electron's surface density are obtained. In\nthis way, the unification explaination of the integer and the fractional\nquantum Hall effects is formulated without the help of the concept of\nfractional charge.",
        "positive": "Optical and electronic properties of low-density InAs/InP quantum\n  dot-like structures devoted to single-photon emitters at telecom wavelengths: Due to their band-structure and optical properties, InAs/InP quantum dots\n(QDs) constitute a promising system for single-photon generation at third\ntelecom window of silica fibers and for applications in quantum communication\nnetworks. However, obtaining the necessary low in-plane density of emitters\nremains a challenge. Such structures are also still less explored than their\nInAs/GaAs counterparts regarding optical properties of confined carriers. Here,\nwe report on the growth via metal-organic vapor phase epitaxy and investigation\nof low-density InAs/InP QD-like structures, emitting in the range of 1.2-1.7\n${\\mu}$m, which includes the S, C, and L bands of the third optical window. We\nobserve multiple photoluminescence (PL) peaks originating from flat QDs with\nheight of small integer numbers of material monolayers. Temperature-dependent\nPL reveals redistribution of carriers between families of QDs. Via\ntime-resolved PL, we obtain radiative lifetimes nearly independent of emission\nenergy in contrast to previous reports on InAs/InP QDs, which we attribute to\nstrongly height-dependent electron-hole correlations. Additionally, we observe\nneutral and charged exciton emission from spatially isolated emitters. Using\nthe 8-band k${\\cdot}$p model and configuration-interaction method, we\nsuccessfully reproduce energies of emission lines, the dispersion of exciton\nlifetimes, carrier activation energies, as well as the biexciton binding\nenergy, which allows for a detailed and comprehensive analysis of the\nunderlying physics."
    },
    {
        "anchor": "Bulk inversion asymmetry induced magnetogyrotropic reflection from\n  quantum wells: Bulk inversion asymmetry (BIA) of III-V and II-VI semiconductor quantum wells\nis demonstrated by reflection experiments in magnetic field oriented in the\nstructure plane. The linear in the magnetic field contribution to the\nreflection coefficients is measured at oblique incidence of $s$ and $p$\npolarized light in vicinity of exciton resonances. We demonstrate that this\ncontribution to the reflection is caused by magnetogyrotropy of quantum wells,\ni.e. by the terms in the optical response which are linear in both the magnetic\nfield strength and light wavevector. Theory of magnetogyrotropic effects in\nlight reflection is developed with account for linear in momentum BIA induced\nterms in the electron and hole effective Hamiltonians. Theoretical estimates\nagree with the experimental findings. We have found the electron BIA splitting\nconstant in both GaAs and CdTe based quantum wells is about three times smaller\nthan that for heavy holes.",
        "positive": "Tailoring the exchange bias effect by in-plane magnetic anisotropy: We report an unusual, non-monotonous dependence of the exchange bias on the\nthickness of the ferromagnetic layer in a ferromagnet/antiferromagnet bilayer\nsystem. We show that in epitaxial CoO/Fe(110) bilayers, the evolution of the Fe\nmagnetic anisotropy, which drives the thickness-induced in-plane\nspin-reorientation process, controls the interfacial CoO spin directions in the\n0-90 degrees range and, consequently, drastically modifies the magnitude of the\nhysteresis loop shift and its dependence on the thickness of the Fe layer. Our\nresults present a new recipe for tailoring the exchange bias and\nantiferromagnetic spin structure by utilizing the spin-reorientation process\nthat occurs in a ferromagnetic layer adjacent to an antiferromagnetic layer."
    },
    {
        "anchor": "Role of electronic excitations in magneto-Raman spectra of graphene: We investigate the signature of the low-energy electronic excitations in the\nRaman spectrum of monolayer and bilayer graphenes. The dominant contribution to\nthe Raman spectra is due to the interband electron-hole pairs, which belong to\nthe irreducible representation A$_2$ of the point group C$_{6v}$ of the\ngraphene lattice, and are characterised by crossed polarisation of incoming and\noutgoing photons. At high magnetic fields, this is manifested by the excitation\nof electron-hole (e-h) inter-Landau-level transitions with selection rule\n$n^-\\to n^+$. Weaker Raman-active inter-Landau-level modes also exist. One of\nthose has a selection rule similar to the infrared absorption process,\n$n^-\\to(n\\pm1)^+$, but the created e-h excitation belongs to the irreducible\nrepresentation E$_2$ (rather than E$_1$) and couples to the optical phonon\nmode, thus undergoing an anticrossing with the optical phonon G-line in Raman\nin strong magnetic field. The fine structure of acquired by the G-line due to\nsuch anticrossing depends on the carrier density, inhomogeneity of doping, and\npresence of inhomogeneous strain in the sample.",
        "positive": "Designer quantum matter in van der Waals heterostructures: Van der Waals materials can be easily combined in lateral and vertical\nheterostructures, providing an outstanding platform to engineer elusive quantum\nstates of matter. However, a critical problem in material science is to\nestablish tangible links between real materials properties and terms that can\nbe cooked up on the model Hamiltonian level to realize different exotic\nphenomena. Our review aims to do precisely this: we first discuss, in a way\naccessible to the materials community, what ingredients need to be included in\nthe hybrid quantum materials recipe, and second, we elaborate on the specific\nmaterials that would possess the necessary qualities. We will review the\nwell-established procedures for realizing 2D topological superconductors,\nquantum spin-liquids and flat bands systems, emphasizing the connection between\nwell-known model Hamiltonians and real compounds. We will use the most recent\nexperimental results to illustrate the power of the designer approach."
    },
    {
        "anchor": "Transconductance fluctuations as a probe for interaction induced quantum\n  Hall states in graphene: Transport measurements normally provide a macroscopic, averaged view of the\nsample, so that disorder prevents the observation of fragile interaction\ninduced states. Here, we demonstrate that transconductance fluctuations in a\ngraphene field effect transistor reflect charge localization phenomena on the\nnanometer scale due to the formation of a dot network which forms near\nincompressible quantum states. These fluctuations give access to fragile\nbroken-symmetry and fractional quantum Hall states even though these states\nremain hidden in conventional magnetotransport quantities.",
        "positive": "Photogalvanic effects in HgTe quantum wells: We report on the observation of the terahertz radiation induced circular\n(CPGE) and linear (LPGE) photogalvanic effects in HgTe quantum wells. The\ncurrent response is well described by the phenomenological theory of CPGE and\nLPGE."
    },
    {
        "anchor": "Fluorine Intercalated Graphene: Formation of a 2D Spin Lattice through\n  Pseudoatomization: A suspended layer made up of ferromagnetically ordered spins could be created\nbetween two mono/multilayer graphene through intercalation. Stability and\nelectronic structure studies show that, when fluorine molecules are\nintercalated between two mono/multilayer graphene, their bonds get stretched\nenough ($\\sim$ 1.9$-$2.0 {\\AA}) to weaken their molecular singlet eigenstate.\nGeometrically, these stretched molecules form a pseudoatomized fluorine layer\nby maintaining a van der Waals separation of $\\sim$ 2.6 {\\AA} from the adjacent\ncarbon layers. As there is a significant charge transfer from the adjacent\ncarbon layers to the fluorine layers, a mixture of triplet and doublet states\nstabilize to induce local spin-moments at each fluorine sites and in turn form\na suspended 2D spin lattice. The spins of this lattice align ferromagnetically\nwith nearest neighbour coupling strength as large as $\\sim$ 100 meV. Our finite\ntemperature \\textit {ab initio} molecular dynamics study reveals that the\nintercalated system can be stabilized up to a temperature of 100 K with an\naverage magnetic moment of $\\sim$ 0.6 $\\mu_{B}$/F. However, if the graphene\nlayers can be held fixed, the room temperature stability of such a system is\nfeasible.",
        "positive": "Tuning of electron transport through a moebius strip: shot noise: We explore electron transport through a moebius strip attached to two\nmetallic electrodes by the use of Green's function technique. A parametric\napproach is used based on the tight-binding model to characterize the electron\ntransport through such a bridge system and it is observed that the transport\nproperties are significantly affected by (a) the transverse hopping strength\nbetween the two channels and (b) the strip-to-electrode coupling strength. In\nthis context we also describe the noise power of the current fluctuations that\nprovides a key information about the electron correlation which is obtained by\ncalculating the Fano factor ($F$). The knowledge of this current fluctuations\ngives important ideas for fabrication of efficient electronic devices."
    },
    {
        "anchor": "Realization of quasicrystalline quadrupole topological insulators in\n  electrical circuits: Quadrupole topological insulators are a new class of topological insulators\nwith quantized quadrupole moments, which support protected gapless corner\nstates. The experimental demonstrations of quadrupole-topological insulators\nwere reported in a series of artificial materials, such as photonic crystals,\nacoustic crystals, and electrical circuits. In all these cases, the underlying\nstructures have discrete translational symmetry and thus are periodic. Here we\nexperimentally realize two-dimensional aperiodic-quasicrystalline\nquadrupole-topological insulators by constructing them in electrical circuits,\nand observe the spectrally and spatially localized corner modes. In\nmeasurement, the modes appear as topological boundary resonances in the corner\nimpedance spectra. Additionally, we demonstrate the robustness of corner modes\non the circuit. Our circuit design may be extended to study topological phases\nin higher-dimensional aperiodic structures.",
        "positive": "An on-chip platform for multi-degree-of-freedom control of\n  two-dimensional quantum and nonlinear materials: Two-dimensional materials (2DM) and their derived heterostructures have\nelectrical and optical properties that are widely tunable via several\napproaches, most notably electrostatic gating and interfacial engineering such\nas twisting. While electrostatic gating is simple and has been ubiquitously\nemployed on 2DM, being able to tailor the interfacial properties in a similar\nreal-time manner represents the next leap in our ability to modulate the\nunderlying physics and build exotic devices with 2DM. However, all existing\napproaches rely on external machinery such as scanning microscopes, which often\nlimit their scope of applications, and there is currently no means of tuning a\n2D interface that has the same accessibility and scalability as electrostatic\ngating. Here, we demonstrate the first on-chip platform designed for 2D\nmaterials with in situ tunable interfacial properties, utilizing a\nmicroelectromechanical system (MEMS). Each compact, cost-effective, and\nversatile device is a standalone micromachine that allows voltage-controlled\napproaching, twisting, and pressurizing of 2DM with high accuracy. As a\ndemonstration, we engineer synthetic topological singularities, known as\nmerons, in the nonlinear optical susceptibility of twisted hexagonal boron\nnitride (h-BN), via simultaneous control of twist angle and interlayer\nseparation. The chirality of the resulting moire pattern further induces a\nstrong circular dichroism in the second-harmonic generation. A potential\napplication of this topological nonlinear susceptibility is to create\nintegrated classical and quantum light sources that have widely and real-time\ntunable polarization. Our invention pushes the boundary of available\ntechnologies for manipulating low-dimensional quantum materials, which in turn\nopens up the gateway for designing future hybrid 2D-3D devices for\ncondensed-matter physics, quantum optics, and beyond."
    },
    {
        "anchor": "Floquet engineering in the presence of optically excited carriers: Floquet engineering provides an optical means to manipulate electronic\nbandstructures, however, carriers excited by the pump field can lead to an\neffective heating, and can obscure measurement of the band changes. A recent\ndemonstration of the effects of Floquet engineering on a coherent ensemble of\nexcitons in monolayer WS$_2$ proved particularly sensitive to non-adiabatic\neffects, while still being able to accurately resolve bandstructure changes.\nHere, we drive an AC-Stark effect in monolayer WS$_2$ using pulses with\nconstant fluence but varying pulse duration (from 25-235~fs). With shorter pump\npulses, the corresponding increase in peak intensity introduces additional\ncarriers via two-photon absorption, leading to additional decoherence and peak\nbroadening (which makes it difficult to resolve the AC-Stark shift). We use\nmultidimensional coherent spectroscopy to create a coherent ensemble of\nexcitons in monolayer WS$_2$ and measure the evolution of the coherence\nthroughout the duration of the Floquet pump pulse. Changes to the amplitude of\nthe macroscopic coherence quantifies the additional broadening. At the same\ntime, the evolution of the average phase allows the instantaneous changes to\nthe bandstructure to be quantified, and is not impacted by the additional\nbroadening. This approach to measuring the evolution of Floquet-Bloch states\ndemonstrates a means to quantify effective heating and non-adiabaticity caused\nby excited carriers, while at the same time resolving the coherent evolution of\nthe bandstructure.",
        "positive": "Optical properties in a two-dimensional quantum ring: Confinement\n  potential and Aharonov-Bohm effect: Optical properties of a two-dimensional quantum ring with pseudopotential in\nthe presence of an external magnetic field and magnetic flux have been\ntheoretically investigated. Our results show that both of the pseudopotential\nand magnetic field can affect the third nonlinear susceptibility and oscillator\nstrength. In addition, we found that the oscillator strength and the absolute\nvalue of the resonant peak of the linear, non-linear and total absorption\ncoefficient vary periodically with magnetic flux, while the resonant peak value\nof the linear, non-linear and total refractive index changes decreases as\nmagnetic flux increases."
    },
    {
        "anchor": "Acoustically regulated optical emission dynamics from quantum dot-like\n  emission centers in GaN/InGaN nanowire heterostructures: We report on experimental studies of the effects induced by surface acoustic\nwaves on the optical emission dynamics of GaN/InGaN nanowire quantum dots. We\nemploy stroboscopic optical excitation with either time-integrated or\ntime-resolved photoluminescence detection. In the absence of the acoustic wave,\nthe emission spectra reveal signatures originated from the recombination of\nneutral exciton and biexciton confined in the probed nanowire quantum dot. When\nthe nanowire is perturbed by the propagating acoustic wave, the embedded\nquantum dot is periodically strained and its excitonic transitions are\nmodulated by the acousto-mechanical coupling. Depending on the recombination\nlifetime of the involved optical transitions, we can resolve acoustically\ndriven radiative processes over time scales defined by the acoustic cycle. At\nhigh acoustic amplitudes, we also observe distortions in the transmitted\nacoustic waveform, which are reflected in the time-dependent spectral response\nof our sensor quantum dot. In addition, the correlated intensity oscillations\nobserved during temporal decay of the exciton and biexciton emission suggest an\neffect of the acoustic piezoelectric fields on the quantum dot charge\npopulation. The present results are relevant for the dynamic spectral and\ntemporal control of photon emission in III-nitride semiconductor\nheterostructures.",
        "positive": "Optical manipulation of layer-valley coherence via strong exciton-photon\n  coupling in microcavities: Coherent control and manipulation of quantum degrees of freedom such as spins\nforms the basis of emerging quantum technologies. In this context, the robust\nvalley degree of freedom and the associated valley pseudospin found in\ntwo-dimensional transition metal dichalcogenides is a highly attractive\nplatform. Valley polarization and coherent superposition of valley states have\nbeen observed in these systems even up to room temperature. Control of valley\ncoherence is an important building block for the implementation of valley\nqubit. Large magnetic fields or high-power lasers have been used in the past to\ndemonstrate the control (initialization and rotation) of the valley coherent\nstates. Here we demonstrate control of layer-valley coherence via strong\ncoupling of valley excitons in bilayer WS2 to microcavity photons by exploiting\nthe pseudomagnetic field arising in optical cavities owing to the TE-TM\nsplitting. The use of photonic structures to generate pseudomagnetic fields\nwhich can be used to manipulate exciton-polaritons presents an attractive\napproach to control optical responses without the need for large magnets or\nhigh intensity optical pump powers."
    },
    {
        "anchor": "Shot Noise of Cotunneling Current: We study the noise of the cotunneling current through one or several\ntunnel-coupled quantum dots in the Coulomb blockade regime. The various regimes\nof weak and strong, elastic and inelastic cotunneling are analyzed for\nquantum-dot systems (QDS) with few-level, nearly-degenerate, and continuous\nelectronic spectra. In the case of weak cotunneling we prove a non-equilibrium\nfluctuation-dissipation theorem, which leads to a universal expression for the\nnoise-to-current ratio (Fano factor). The noise of strong inelastic cotunneling\ncan be super-Poissonian due to switching between QDS states carrying currents\nof different strengths. The transport through a double-dot (DD) system shows an\nAharonov-Bohm effect both in noise and current. In the case of cotunneling\nthrough a QDS with a continuous energy spectrum the Fano factor is very close\nto one.",
        "positive": "Long ranged interactions in carbon atomic chains: Based on first-principles calculations we revealed fundamental properties of\ninfinite and finite size monatomic chains of carbon atoms in equilibrium and\nunder an applied strain. Distributions of bond lengths and magnetic moments at\natomic sites exhibit interesting even-odd disparity depending on the number of\ncarbon atoms in the chain and on the type of saturation of carbon atoms at both\nends. It was shown that, the $\\pi$-bands of carbon atomic chains behave as a\none dimensional free electron system. A local perturbation created by a small\ndisplacement of the single carbon atom at the center of a long chain induces\noscillations of atomic forces and charge density, which are carried to long\ndistances over the chain. These long ranged oscillations are identified as\nFriedel oscillations showing $1/r$ decay rate in one dimensional systems."
    },
    {
        "anchor": "Magnetic induction dependence of the dispersion of magnetoplasmon in a\n  two-dimensional electron gas with finite layer thickness: Magnetic induction dependence of the dispersion of longitudinal\nmagnetoplasmon in a two-dimensional electron gas with finite layer thickness\nunder a static uniform magnetic field normal to the layer plane is calculated\nusing the self-consistent linear response approximation. Two longitudinal\nmagnetoplasmon modes are obtained. The calculated dispersion agrees with the\nexperiment by Batke {\\it et al.} [Phys. Rev. B {\\bf 34}, 6951 (1986)].",
        "positive": "Magneto-spectroscopy of excited states in charge-tunable GaAs/AlGaAs\n  [111] quantum dots: We present a combined experimental and theoretical study of highly charged\nand excited electron-hole complexes in strain-free (111) GaAs/AlGaAs quantum\ndots grown by droplet epitaxy. We address the complexes with one of the charge\ncarriers residing in the excited state, namely, the ``hot'' trions X$^{-*}$ and\nX$^{+*}$, and the doubly negatively charged exciton X$^{2-}$. Our\nmagneto-photoluminescence experiments performed on single quantum dots in the\nFaraday geometry uncover characteristic emission patterns for each excited\nelectron-hole complex, which are very different from the photoluminescence\nspectra observed in (001)-grown quantum dots. We present a detailed theory of\nthe fine structure and magneto-photoluminescence spectra of X$^{-*}$, X$^{+*}$\nand X$^{2-}$ complexes, governed by the interplay between the electron-hole\nCoulomb exchange interaction and the heavy-hole mixing, characteristic for\nthese quantum dots with a trigonal symmetry. Comparison between experiment and\ntheory of the magneto-photoluminescence allows for precise charge state\nidentification, as well as extraction of electron-hole exchange interaction\nconstants and $g$-factors for the charge carriers occupying excited states."
    },
    {
        "anchor": "Effect of interface geometry on electron tunnelling in Al/Al$_2$O$_3$/Al\n  junctions: We investigate how different interface geometries of an Al/Al$_2$O$_3$\njunction, a common component of modern tunnel devices, affect electron\ntransport through the tunnel barrier. We study six distinct Al/Al$_2$O$_3$\ninterfaces which differ in stacking sequences of the metal and the oxide\nsurface atoms and the oxide termination. To construct model potential barrier\nprofiles for each examined geometry, we rely on first-principles\ndensity-functional theory (DFT) calculations for the barrier heights and the\nshapes of the interface regions as well as on experimental data for the barrier\nwidths. We show that even tiny variations in the atomic arrangement at the\ninterface cause significant changes in the tunnel barrier parameters and,\nconsequently, in electron transport properties. Especially, we obtain that\nvariations in the crucial barrier heights and widths can be as large as 2 eV\nand 5 \\AA, respectively. Finally, to gain information about the average\nproperties of the measured junction, we fit the conductance calculated within\nthe WKB approximation to the experimental data and interpret the fit parameters\nwith the help of the DFT results.",
        "positive": "Quantum Anomalous Hall effect in graphene coupled to skyrmions: Skyrmions are topologically protected spin textures, characterized by a\ntopological winding number N , that occur spontaneously in some magnetic\nmaterials. Recent experiments have demonstrated the capability to grow graphene\non top Fe/Ir, a system that exhibits a two dimensional Skyrmion lattice. Here\nwe show that a weak exchange coupling between the Dirac electrons in graphene\nand a two dimensional Skyrmion lattice with $N = \\pm 1$ drives graphene into a\nquantum anomalous Hall phase, with a band-gap in bulk, a Chern number ${\\cal\nC}=2N$ and chiral edge states with perfect quantization of conductance $G =\n2N\\frac{e^2}{h}$ . Our findings imply that the topological properties of the\nSkyrmion lattice can be imprinted in the Dirac electrons of graphene."
    },
    {
        "anchor": "Quantum Computing with Acceptor Spins in Silicon: The states of a boron acceptor near a Si/SiO2 interface, which bind two\nlow-energy Kramers pairs, have exceptional properties for encoding quantum\ninformation and, with the aid of strain, both heavy hole and light hole-based\nspin qubits can be designed. Whereas a light-hole spin qubit was introduced\nrecently [Phys. Rev. Lett. 116, 246801 (2016)], here we present analytical and\nnumerical results proving that a heavy-hole spin qubit can be reliably\ninitialised, rotated and entangled by electrical means alone. This is due to\nstrong Rashba-like spin-orbit interaction terms enabled by the interface\ninversion asymmetry. Single qubit rotations rely on electric-dipole spin\nresonance (EDSR), which is strongly enhanced by interface-induced spin-orbit\nterms. Entanglement can be accomplished by Coulomb exchange, coupling to a\nresonator, or spin-orbit induced dipole-dipole interactions. By analysing the\nqubit sensitivity to charge noise, we demonstrate that interface-induced\nspin-orbit terms are responsible for sweet spots in the dephasing time T2* as a\nfunction of the top gate electric field, which are close to maxima in the EDSR\nstrength, where the EDSR gate has high fidelity. We show that both qubits can\nbe described using the same starting Hamiltonian, and by comparing their\nproperties we show that the complex interplay of bulk and interface-induced\nspin-orbit terms allows a high degree of electrical control and makes acceptors\npotential candidates for scalable quantum computation in Si.",
        "positive": "Terahertz Strong-Field Physics without a Strong External Terahertz Field: Traditionally, strong-field physics explores phenomena in matter (atoms,\nmolecules, and solids) driven by an extremely strong laser field\nnonperturbatively. However, even in the complete absence of an external\nelectromagnetic field, strong-field phenomena can arise when matter strongly\ncouples with the zero-point field of the quantum vacuum state, i.e.,\nfluctuating electromagnetic waves whose expectation value is zero. Some of the\nmost striking examples of this occur in a cavity setting, in which an ensemble\nof two-level atoms resonantly interacts with a single photonic mode of vacuum\nfields, producing vacuum Rabi splitting. In particular, the nature of the\nmatter-vacuum-field coupled system fundamentally changes when the coupling rate\n(equal to one half of the vacuum Rabi splitting) becomes comparable to, or\nlarger than, the resonance frequency. In this so-called ultrastrong coupling\nregime, a non-negligible number of photons exist in the ground state of the\ncoupled system. Furthermore, the coupling rate can be cooperatively enhanced\n(via so-called Dicke cooperativity) when the matter is comprised of a large\nnumber of identical two-level particles, and a quantum phase transition is\npredicted to occur as the coupling rate reaches a critical value. Low-energy\nelectronic or magnetic transitions in many-body condensed matter systems with\nlarge dipole moments are ideally suited for searching for these predicted\nphenomena. Here, we discuss two condensed matter systems that have shown\ncooperative ultrastrong interactions in the terahertz frequency range: a\nLandau-quantized two-dimensional electron gas interacting with\nhigh-quality-factor cavity photons, and an Er$^{3+}$ spin ensemble interacting\nwith Fe$^{3+}$ magnons in ErFeO$_3$."
    },
    {
        "anchor": "Disorder-induced topological superconductivity in a spherical\n  quantum-Hall--superconductor hybrid: Quantum-Hall--Superconductor hybrids have been predicted to exhibit various\ntypes of topological order, providing possible platforms for intrinsically\nfault-tolerant quantum computing. In this paper, we develop a formulation to\nconstruct this hybrid system on a sphere, a useful geometry for identifying\ntopologically ordered states due to its compact and contractible nature. As a\npreliminary step using this framework, we investigate disorder effects on the\nRashba-coupled quantum Hall system combined with the type-II superconductor. By\ndiagonalizing the BdG Hamiltonian projected into a Rashba-coupled Landau level,\nwe demonstrate the emergence of a topological superconducting phase resulting\nfrom disorders and proximity-induced pairing. Distinctive gapless modes appear\nin the real-space entanglement spectrum, which is consistent with topological\nsuperconductivity.",
        "positive": "Influence of polarization and self-polarization charges on impurity\n  binding energy in spherical quantum dot with parabolic confinement: We present a general formulation of the ground state binding energy of a\nshallow hydrogenic impurity in spherical quantum dot with parabolic\nconfinement, considering the effects of polarization and self energy. The\nvariational approach within the effective mass approximation is employed here.\nThe binding energy of an on-center impurity is computed for a $\\mathrm{GaAs}$/\n$\\mathrm{{Al}_{x}{Ga}_{1-x}As}$ quantum dot as a function of the dot size with\nthe dot barrier as parameter. The influence of polarization and self energy are\nalso treated separately. Results indicate that the binding energy increases due\nto the presence of polarization charge, while decreases due to the self energy\nof the carrier. An overall enhancement in impurity binding energy, especially\nfor small dots is noted."
    },
    {
        "anchor": "Large-Range Frequency Tuning of a Narrow-Linewidth Quantum Emitter: A hybrid system of a semiconductor quantum dot single photon source and a\nrubidium quantum memory represents a promising architecture for future photonic\nquantum repeaters. One of the key challenges lies in matching the emission\nfrequency of quantum dots with the transition frequency of rubidium atoms while\npreserving the relevant emission properties. Here, we demonstrate the\nbidirectional frequency-tuning of the emission from a narrow-linewidth\n(close-to-transform-limited) quantum dot. The frequency tuning is based on a\npiezoelectric strain-amplification device, which can apply significant stress\nto thick bulk samples. The induced strain shifts the emission frequency of the\nquantum dot over a total range of $1.15\\ \\text{THz}$, about three orders of\nmagnitude larger than its linewidth. Throughout the whole tuning process, both\nthe spectral properties of the quantum dot and its single-photon emission\ncharacteristics are preserved. Our results show that external stress can be\nused as a promising tool for reversible frequency tuning of high-quality\nquantum dots and pave the wave towards the realisation of a quantum dot --\nrubidium atoms interface for quantum networking.",
        "positive": "Amplification of spin-filtering effect by magnetic field in GaAsN alloys: We have found that intensity $I$ and circular polarization degree $\\rho$ of\nthe edge photoluminescence, excited in GaAsN alloys by circularly polarized\nlight at room temperature, grow substantially in the longitudinal magnetic\nfield $B$ of the order of 1\\,kG. This increase depends on the intensity of\npumping and, in the region of weak or moderate intensities, may reach a twofold\nvalue. In two-charge-state model, which considers spin-dependent recombination\nof spin-oriented free electrons on deep paramagnetic centers, we included the\nmagnetic-field suppression of spin relaxation of the electrons bound on\ncenters. The model describes qualitatively the rise of $\\rho$ and $I$ in a\nmagnetic field under different pump intensities. Experimental dependences\n$\\rho(B)$ and $I(B)$ are shifted with respect to zero of the magnetic field by\na value of $\\sim$170\\,Gauss, while the direction of the shift reverses with\nchange of the sign of circular polarization of pumping. As a possible cause of\nthe discovered shift we consider the Overhauser field, arising due to the\nhyperfine interaction of an electron bound on a center with nuclei of the\ncrystal lattice in the vicinity of the center."
    },
    {
        "anchor": "Transmission in graphene-topological insulator heterostructures: We investigate scattering of the topological surface state of a\nthree-dimensional time-reversal invariant topological insulator when graphene\nis deposited on the topological-insulator surface. Specifically, we consider\nthe (111) surface of a Bi$_2$Se$_3$-like topological insulator. We present a\nlow-energy model for the bulk graphene-topological insulator heterostructure\nand we calculate the transmission probability at zigzag and armchair edges of\nthe deposited graphene, and the conductance through graphene nanoribbon\nbarriers and show that its features can be understood from antiresonances in\nthe transmission probability.",
        "positive": "Quantum Size Effects on the Chemical Sensing Performance of\n  Two-Dimensional Semiconductors: We investigate the role of quantum confinement on the performance of gas\nsensors based on two-dimensional InAs membranes. Pd-decorated InAs membranes\nconfigured as H2 sensors are shown to exhibit strong thickness dependence, with\n~100x enhancement in the sensor response as the thickness is reduced from 48 to\n8 nm. Through detailed experiments and modeling, the thickness scaling trend is\nattributed to the quantization of electrons which favorably alters both the\nposition and the transport properties of charge carriers; thus making them more\nsusceptible to surface phenomena."
    },
    {
        "anchor": "Spin Orbit Coupling and Spin Waves in Ultrathin Ferromagnets: The Spin\n  Wave Rashba Effect: We present theoretical studies of the influence of spin orbit coupling on the\nspin wave excitations of the Fe monolayer and bilayer on the W(110) surface.\nThe Dzyaloshinskii-Moriya interaction is active in such films, by virtue of the\nabsence of reflection symmetry in the plane of the film. When the magnetization\nis in plane, this leads to a linear term in the spin wave dispersion relation\nfor propagation across the magnetization. The dispersion relation thus assumes\na form similar to that of an energy band of an electron trapped on a\nsemiconductor surfaces with Rashba coupling active. We also show SPEELS\nresponse functions that illustrate the role of spin orbit coupling in such\nmeasurements. In addition to the modifications of the dispersion relations for\nspin waves, the presence of spin orbit coupling in the W substrate leads to a\nsubstantial increase in the linewidth of the spin wave modes. The formalism we\nhave developed applies to a wide range of systems, and the particular system\nexplored in the numerical calculations provides us with an illustration of\nphenomena which will be present in other ultrathin ferromagnet/substrate\ncombinations.",
        "positive": "Signature of a topological phase transition in long SN junctions in the\n  spin-polarized density of states: We investigate the spin texture of Andreev bound states and Majorana states\nin long SN junctions. We show that measuring the spin-polarized density of\nstates (SPDOS) allows one to identify the topological transition. In\nparticular, we find that its total component parallel to the wire is non-zero\nin the topological phase for the lowest-energy state, while vanishing in the\ntrivial one. Also, the component parallel to the Zeeman field is symmetric\nbetween positive and negative energies in the topological phase and asymmetric\nin the trivial phase. Moreover the SPDOS exhibits a moderate accumulation close\nto the SN boundary which changes sign when crossing the topological transition.\nWe propose that these signatures may allow one to unambiguously test the\nformation of a topological phase via spin-resolved transport and STM\nmeasurements."
    },
    {
        "anchor": "Full Counting Statistics with Spin-sensitive Detectors reveals\n  Spin-singlets: We study the full counting statistics of electric current to several drain\nterminals with spin-dependent entrance conductances. We show that the\nstatistics of charge transfers can be interpreted in terms of single electrons\nand spin-singlet pairs coming from the source. If the source contains transport\nchannels of high transparency, a significant fraction of electrons comes in\nspin-singlet pairs.",
        "positive": "Spin Susceptibility of Interacting Two-dimensional Electrons with\n  Anisotropic Effective Mass: We report measurements of the spin susceptibility in dilute (rs up to 10)\nAlAs two-dimensional (2D) electrons occupying a single conduction-band valley\nwith an anisotropic in-plane Fermi contour, characterized by longitudinal and\ntransverse effective masses, ml and mt. As the density is decreased, the spin\nsusceptibility is significantly enhanced over its band value, reflecting the\nrole of interaction. Yet the enhancement is suppressed compared to the results\nof quantum Monte Carlo based calculations that take the finite thickness of the\nelectron layer into account but assume an isotropic effective mass equal to\nsqrt(ml.mt). Proper treatment of an interacting 2D system with an anisotropic\neffective mass therefore remains a theoretical challenge."
    },
    {
        "anchor": "Particle-hole symmetry and composite fermions in fractional quantum Hall\n  states: We study fractional quantum Hall states at filling fractions in the Jain\nsequences using the framework of composite Dirac fermions. Synthesizing\nprevious work, we write down an effective field theory consistent with all\nsymmetry requirements, including Galilean invariance and particle-hole\nsymmetry. Employing a Fermi liquid description, we demonstrate the appearance\nof the Girvin--Macdonlald--Platzman algebra and compute the dispersion relation\nof neutral excitations and various response functions. Our results satisfy\nrequirements of particle-hole symmetry. We show that while the dispersion\nrelation obtained from the HLR theory is particle-hole symmetric, correlation\nfunctions obtained from HLR are not. The results of the Dirac theory are shown\nto be consistent with the Haldane bound on the projected structure factor,\nwhile those of the HLR theory violate it.",
        "positive": "Coulomb staircase in an asymmetrically coupled quantum dot: We investigate the Coulomb blockade in quantum dots asymmetrically coupled to\nthe leads for an arbitrary voltage bias focusing on the regime where electrons\ndo not thermalise during their dwell time in the dot. By solving the quantum\nkinetic equation, we show that the current-voltage characteristics are\ncrucially dependent on the ratio of the Fermi energy to charging energy on the\ndot. In the standard regime when the Fermi energy is large, there is a Coulomb\nstaircase which is practically the same as in the thermalised regime. In the\nopposite case of the large charging energy, we identify a new regime in which\nonly one step is left in the staircase, and we anticipate experimental\nconfirmation of this finding."
    },
    {
        "anchor": "Exploring the parameter space of disc shaped silver nanoparticles for\n  thin film silicon photovoltaics: We numerically simulate, using finite-difference time-domain, the optical\nproperties of silver nano discs deposited on the front surface of silicon solar\ncells. We explore the effect of each of the parameters of such a system, in\norder to draw some general design rules for the subsequent fabrication of such\nstructures.",
        "positive": "Non-Markovian electron dynamics in nanostructures coupled to dissipative\n  contacts: In quasiballistic semiconductor nanostructures, carrier exchange between the\nactive region and dissipative contacts is the mechanism that governs\nrelaxation. In this paper, we present a theoretical treatment of transient\nquantum transport in quasiballistic semiconductor nanostructures, which is\nbased on the open system theory and valid on timescales much longer than the\ncharacteristic relaxation time in the contacts. The approach relies on a model\ninteraction between the current-limiting active region and the contacts, given\nin the scattering-state basis. We derive a non-Markovian master equation for\nthe irreversible evolution of the active region's many-body statistical\noperator by coarse-graining the exact dynamical map over the contact relaxation\ntime. In order to obtain the response quantities of a nanostructure under bias,\nsuch as the potential and the charge and current densities, the non-Markovian\nmaster equation must be solved numerically together with the Schr\\\"{o}dinger,\nPoisson, and continuity equations. We discuss how to numerically solve this\ncoupled system of equations and illustrate the approach on the example of a\nsilicon nin diode."
    },
    {
        "anchor": "Theory of the spin Hall effect, and its inverse, in a ferromagnetic\n  metal near the Curie temperature: We give a theory of the inverse spin Hall effect (ISHE) in ferromagnetic\nmetals based on skew scattering via collective spin fluctuations. This extends\nKondo's theory of the anomalous Hall effect (AHE) to include short-range\nspin-spin correlations. We find a relation between the ISHE and the four-spin\ncorrelations near the Curie temperature TC. Such four-spin correlations do not\ncontribute to the AHE, which relates to the three-spin correlations. Thus our\ntheory shows an essential difference between the AHE and ISHE, providing an\nessential complement to Kondo's classic theory of the AHE in metals. We note\nthe relation to skew-scattering mechanisms based on impurity scattering. Our\ntheory can be compared to recent experimental results byWei et al. [Nat.\nCommun. 3, 1058 (2012)] for the ISHE in ferromagnetic alloys.",
        "positive": "Unveiling a Pump-Induced Magnon Mode via its Strong Interaction with\n  Walker Modes: We observe a power-dependent anticrossing of Walker spin-wave modes under\nmicrowave pumping when a ferrimagnet is placed in a microwave waveguide that\ndoes not support any discrete photon mode. We interpret this unexpected\nanticrossing as the generation of a pump-induced magnon mode that couples\nstrongly to the Walker modes of the ferrimagnet. This anticrossing inherits an\nexcellent tunability from the pump, which allows us to control the anticrossing\nvia the pump power, frequency, and waveform. Further, we realize a remarkable\nfunctionality of this anticrossing, namely, a microwave frequency comb, in\nterms of the nonlinear interaction that mixes the pump and probe frequencies.\nSuch a frequency comb originates from the magnetic dynamics and thereby does\nnot suffer from the charge noise. The unveiled hybrid magnonics driven away\nfrom its equilibrium enriches the utilization of anticrossing for coherent\ninformation processing."
    },
    {
        "anchor": "Phonon-assisted thermoelectric effects in a two-level molecule: Thermoelectric properties of a two-level molecule attached to the metallic\nelectrodes are analyzed using the equation of motion technique within the Green\nfunction formalism. Results show that the electrical conductance is strongly\ndependent on the electron and phonon temperatures and the electron-phonon\ncoupling strength. In addition, it is observed that the thermal conductance\npeaks in the electron-hole symmetry points are vanished in the presence of the\nstrong electron-phonon interaction. It is also found that the figure of merit\nis strongly suppressed in the strong electron-phonon interaction. The violation\nof the Wiedemann-Franz law is also observed coming from the Coulomb\ninteractions.",
        "positive": "Direct observation of corner states in second-order topological photonic\n  crystal slabs: Recently, higher-order topological phases that do not obey the usual\nbulk-edge correspondence principle have been introduced in electronic\ninsulators and brought into classical systems, featuring with in-gap\ncorner/hinge states. So far, second-order topological insulators have been\nrealized in mechanical metamaterials, microwave circuit, topolectrical circuit\nand acoustic metamaterials. Here, using near-field scanning measurements, we\nshow the direct observation of corner states in second-order topological\nphotonic crystal (PC) slabs consisting of periodic dielectric rods on a perfect\nelectric conductor (PEC). Based on the generalized two-dimensional (2D)\nSu-Schrieffer-Heeger (SSH) model, we show that the emergence of corner states\nroots in the nonzero edge dipolar polarization instead of the nonzero bulk\nquadrupole polarization. We demonstrate the topological transition of 2D Zak\nphases of PC slabs by tuning intra-cell distances between two neighboring rods.\nWe also directly observe in-gap 1D edge states and 0D corner states in the\nmicrowave regime. Our work presents that the PC slab is a powerful platform to\ndirectly observe topological states, and paves the way to study higher-order\nphotonic topological insulators."
    },
    {
        "anchor": "Chiral symmetry and bulk--boundary correspondence in periodically driven\n  one-dimensional systems: Over the past few years, topological insulators have taken center stage in\nsolid state physics. The desire to tune the topological invariants of the bulk\nand thus control the number of edge states has steered theorists and\nexperimentalists towards periodically driving parameters of these systems. In\nsuch periodically driven setups, by varying the drive sequence the effective\n(Floquet) Hamiltonian can be engineered to be topological: then, the principle\nof bulk--boundary correspondence guarantees the existence of robust edge\nstates. It has also been realized, however, that periodically driven systems\ncan host edge states not predicted by the Floquet Hamiltonian. The exploration\nof such edge states, and the corresponding topological phases unique to\nperiodically driven systems, has only recently begun. We contribute to this\ngoal by identifying the bulk topological invariants of periodically driven\none-dimensional lattice Hamiltonians with chiral symmetry. We find simple\nclosed expressions for these invariants, as winding numbers of blocks of the\nunitary operator corresponding to a part of the time evolution, and ways to\ntune these invariants using sublattice shifts. We illustrate our ideas on the\nperiodically driven Su-Schrieffer-Heeger model, which we map to a discrete time\nquantum walk, allowing theoretical results about either of these systems to be\napplied to the other. Our work helps interpret the results of recent\nsimulations where a large number of Floquet Majorana fermions in periodically\ndriven superconductors have been found, and of recent experiments on discrete\ntime quantum walks.",
        "positive": "Phonon-mediated negative differential conductance in molecular quantum\n  dots: Transport through a single molecular conductor is considered, showing\nnegative differential conductance behavior associated with phonon-mediated\nelectron tunneling processes. This theoretical work is motivated by a recent\nexperiment by Leroy et al. using a carbon nanotube contacted by an STM tip\n[Nature {\\bf 432}, 371 (2004)], where negative differential conductance of the\nbreathing mode phonon side peaks could be observed. A peculiarity of this\nsystem is that the tunneling couplings which inject electrons and those which\ncollect them on the substrate are highly asymmetrical. A quantum dot model is\nused, coupling a single electronic level to a local phonon, forming polaron\nlevels. A \"half-shuttle\" mechanism is also introduced. A quantum kinetic\nformulation allows to derive rate equations. Assuming asymmetric tunneling\nrates, and in the absence of the half-shuttle coupling, negative differential\nconductance is obtained for a wide range of parameters. A detailed explanation\nof this phenomenon is provided, showing that NDC is maximal for intermediate\nelectron-phonon coupling. In addition, in absence of a gate, the \"floating\"\nlevel results in two distinct lengths for the current plateaus, related to the\ncapacitive couplings at the two junctions. It is shown that the \"half-shuttle\"\nmechanism tends to reinforce the negative differential regions, but it cannot\ntrigger this behavior on its own."
    },
    {
        "anchor": "Space, matter and topology: An old branch of mathematics, Topology, has opened the road to the discovery\nof new phases of matter. A hidden topology in the energy spectrum is the key\nfor novel conducting/insulating properties of topological matter.",
        "positive": "Breakdown of continuum mechanics for nanometer-wavelength rippling of\n  graphene: Understanding how the mechanical behavior of materials deviates at the\nnanoscale from the macroscopically established concepts is a key challenge of\nparticular importance for graphene, given the complex interplay between its\nnanoscale morphology and electronic properties. In this work, the (sub-)\nnanometer wavelength periodic rippling of suspended graphene nanomembranes has\nbeen realized by thermal strain-engineering and investigated using Scanning\nTunneling Microscopy. This allows us to explore the rippling of a crystalline\nmembrane with wavelengths comparable to its lattice constant. The observed\nnanorippling mode violates the predictions of the continuum model, and\nevidences the breakdown of the plate idealization of the graphene monolayer.\nNevertheless, microscopic simulations based on a quantum mechanical description\nof the chemical binding accurately describe the observed rippling mode and\nelucidate the origin of the continuum model breakdown. Spatially resolved\ntunneling spectroscopy measurements indicate a substantial influence of the\nnanoripples on the local electronic structure of graphene and reveal the\nformation of one-dimensional electronic superlattices."
    },
    {
        "anchor": "Delicate Topology of Luttinger Semimetal: Recent advances in delicate topology have expanded the classification of\ntopological bands, but its presence in solid-state materials remains elusive.\nHere we show that delicate topology naturally emerges in the Luttinger-Kohn\nmodel that describes many semiconductors and semimetals. In particular, the\nLuttinger semimetal is found to be a quantum critical point leading to a\nquantized jump of an integer-valued delicate topological invariant. Away from\nthis criticality, we have identified new types of electronic insulators and\nsemimetals with intertwined stable and delicate topologies. They all carry\ngapless surface states that transform anomalously under rotation symmetry. Our\nwork provides a starting point for exploring delicate topological phenomena in\nquantum materials.",
        "positive": "Defective transport properties of three-terminal carbon nanotube\n  junctions: We investigate the transport properties of three terminal carbon based\nnanojunctions within the scattering matrix approach. The stability of such\njunctions is subordinated to the presence of nonhexagonal arrangements in the\nmolecular network. Such \"defective\" arrangements do influence the resulting\nquantum transport observables, as a consequence of the possibility of acting as\npinning centers of the correspondent wavefunction. By investigating a fairly\nwide class of junctions we have found regular mutual dependencies between such\nlocalized states at the carbon network and a strikingly behavior of the\nconductance. In particular, we have shown that Fano resonances emerge as a\nnatural result of the interference between defective states and the extended\ncontinuum background. As a consequence, the currents through the junctions\nhitting these resonant states might experience variations on a relevant scale\nwith current modulations of up to 75%."
    },
    {
        "anchor": "Bose-Einstein condensation of polaritons in graphene in a high magnetic\n  field: The Bose-Einstein condensation (BEC) of magnetoexcitonic polaritons in a\ngraphene layer embedded in a optical microcavity in a high magnetic field $B$\nis predicted. The essential property of this system (in contrast, e.g., to a\nquantum well embedded in a cavity) is stronger influence of magnetic field and\nweaker influence of disorder. A two-dimensional (2D) magnetoexcitonic\npolaritons gas is considered in a planar harmonic electric field potential\napplied to excitons or a parabolic shape of the optical cavity causing the\ntrapping of microcavity photons. It is shown that the effective polariton mass\n$M_{\\rm eff}$ increases with magnetic field as $B^{1/2}$. The BEC critical\ntemperature $T_{c}^{(0)}$ decreases as $B^{-1/4}$ and increases with the spring\nconstant of the parabolic trap. The Rabi splitting related to the creation of a\nmagnetoexciton in a high magnetic field in graphene is obtained.",
        "positive": "Quantum Sticking of Atoms on Membranes: A continuum model for low-energy physisorption on a membrane under tension is\nproposed and studied with variational mean-field theory. A discontinuous change\nin the energy-dependent sticking coefficient is predicted under certain\nconditions. This singularity is a result of the bosonic orthogonality\ncatastrophe of the vibrational states of the membrane. The energy-dependent\nsticking coefficient is predicted to have exponential scaling in 1/E above the\nsingularity. The application of this model to the quantum sticking of cold\nhydrogen to suspended graphene is discussed. The model predicts that a beam of\natomic hydrogen can be completely reflected by suspended graphene at ultralow\nenergies."
    },
    {
        "anchor": "Polarization Dependence of Raman Spectra in Strained Graphene: The polarization dependences of the G, D, and 2D (G$'$) bands in Raman\nspectra at graphene bulk and edge are examined theoretically. The 2D and D\nbands have different selection rules at bulk and edge. At bulk, the 2D band\nintensity is maximum when the polarization of the scattered light is parallel\nto that of incident light, whereas the D band intensity does not have a\npolarization dependence. At edge, the 2D and D bands exhibit a selection rule\nsimilar to that of the G band proposed in a previous paper. We suggest that a\nconstraint equation on the axial velocity caused by the graphene edge is\nessential for the dependence of the G band on the crystallographic orientation\nobserved in the bulk of strained graphene. This is indicative of that the\npseudospin and valleyspin in the bulk of graphene can not be completely free\nfrom the effect of surrounding edge. The status of the experiments on the G and\nD bands at the graphene edge is mentioned.",
        "positive": "Cavity-resonant excitation for efficient single photon generation: We present an efficiently pumped single photon source based on single quantum\ndots (QD) embedded in photonic crystal nanocavities. Resonant excitation of a\nQD via a higher order cavity mode results in a 100$\\times$ reduced optical\npower at the saturation onset of the photoluminescence, compared with\nexcitation at the same frequency, after the cavity mode is detuned.\nFurthermore, we demonstrate that this excitation scheme leads to selective\nexcitation of QDs coupled to the cavity by comparing photoluminescence and\nauto-correlation spectra for the same excitation wavelength with and without\nthe cavity mode. This provides much cleaner conditions for single photon\ngeneration."
    },
    {
        "anchor": "Magnetic-field-driven topological transitions in non-centrally-symmetric\n  energy spectrum of 2D electron gas with Rashba-Dresselhaus spin-orbit\n  interaction: Spin orbit interaction (SOI) having a complicated energy spectrum with a\nconical point and four critical points are promising candidates to observe\nelectron topological transitions. In the present paper we have investigated the\nevolution of the electron spectrum and isoenergetic contours under the\ninfluence of parallel magnetic field. General formulas for energies of critical\npoints for arbitrary values of SOI constants and magnetic field are found. The\nexistence of critical magnetic fields at which a number of critical points is\nchanged has been predicted. The magnetic field driving topological Lifshitz\ntransitions in the geometry of isoenergetic contours have been studied. Van\nHove's singularities in the electron density of states are calculated. The\nobtained results can be used for theoretical investigations of different\nelectron characteristics of such 2D systems.",
        "positive": "The overlooked role of band-gap parameter in characterization of Landau\n  levels in a gapped phase semi-Dirac system: the monolayer phosphorene case: Two-dimensional gapped semi-Dirac (GSD) materials are systems with a finite\nband gap that their charge carriers behave relativistically in one direction\nand Schr\\\"odinger-like in the other. In the present work, we show that besides\nthe two well-known energy bands features (curvature and chirality), the\nband-gap parameter also play a crucial role in the index- and magnetic\nfield-dependence of the Landau levels (LLs) in a GSD system. We take the\nmonolayer phosphorene as a GSD representative example to explicitly provide\nphysical insights into the role of this parameter in determining the index- and\nmagnetic field-dependence of LLs. We derive an effective one-dimensional\nSchr\\\"odinger equation for charge carriers in the presence of a perpendicular\nmagnetic field and argue that the form of its effective potential is clearly\nsensitive to a dimensionless band-gap that is tunable by structural parameters.\nThe theoretical magnitude of this effective gap and its interplay with oval\nshape $k$-space cyclotron orbits resolve the seeming contradiction in\ndetermining the type of the quantum Hall effect in the pristine monolayer\nphosphorene. Our results strongly confirm that the dependence of LLs on the\nmagnetic field in this GSD material is as conventional two-dimensional\nsemiconductor electron gases up to a very high field regime. Using the\nstrain-induced gap modification scheme, we show the field dependence of the LLs\ncontinuously evolves into $B^{2/3}$ behavior, which holds for a gapless\nsemi-Dirac system. The highlighted role of the band-gap parameter may affect\nthe consequences of the band anisotropy in the physical properties of a GSD\nmaterial, including magnetotransport, optical conductivity, dielectric\nfunction, and thermoelectric performance."
    },
    {
        "anchor": "Nexus and Dirac lines in topological materials: We consider the $Z_2$ topology of the Dirac lines, i.e., lines of band\ncontacts, on an example of graphite. Four lines --- three with topological\ncharge $N_1=1$ each and one with $N_1=-1$ --- merge together near the H-point\nand annihilate due to summation law $1+1+1-1=0$. The merging point is similar\nto the real-space nexus, an analog of the Dirac monopole at which the $Z_2$\nstrings terminate.",
        "positive": "Collective modes in interacting two-dimensional tomographic Fermi\n  liquids: We develop an analytically solvable model for interacting two-dimensional\nFermi liquids with separate collisional relaxation rates for parity-odd and\nparity-even Fermi surface deformations. Such a disparity of collisional\nlifetimes exists whenever scattering is restricted to inversion-symmetric Fermi\nsurfaces, and should thus be a generic feature of two-dimensional Fermi\nliquids. It implies an additional unanticipated \"tomographic\" transport regime\n(in between the standard collisionless and hydrodynamic regimes) in which\neven-parity modes are overdamped while odd-parity modes are collisionless. We\nderive expressions for both the longitudinal and the transverse conductivity\nand discuss the collective mode spectrum along the\ncollisionless-tomographic-hydrodynamic crossover. Longitudinal modes cross over\nfrom zero sound in the collisionless regime to hydrodynamic first sound in the\ntomographic and hydrodynamic regime, where odd-parity damping appears as a\nsubleading correction to the lifetime. In charged Fermi liquids with long-range\nCoulomb coupling, these modes reduce to plasmons with a strongly suppressed\nodd-parity correction to the damping. The transverse response, by contrast, has\na specific tomographic transport regime with two imaginary odd-parity modes,\none of which requires a finite repulsive interaction, distinct from both the\nshear sound in the collisionless regime and an overdamped diffusive current\nmode in the hydrodynamic limit. Our work demonstrates that there are deep\nmany-body aspects of interacting Fermi liquids, which are often thought to be\nwell understood theoretically, remaining unexplored."
    },
    {
        "anchor": "Giant orbital Hall effect and orbital-to-spin conversion in 3d, 5d, and\n  4f metallic heterostructures: The orbital Hall effect provides an alternative means to the spin Hall effect\nto convert a charge current into a flow of angular momentum. Recently,\ncompelling signatures of orbital Hall effects have been identified in 3d\ntransition metals. Here, we report a systematic study of the generation,\ntransmission, and conversion of orbital currents in heterostructures comprising\n3d, 5d, and 4f metals. We show that the orbital Hall conductivity of Cr reaches\ngiant values of the order of 5*10^5 Ohm^{-1} m^{-1} and that Pt presents a\nstrong orbital Hall effect in addition to the spin Hall effect. Measurements\nperformed as a function of thickness of nonmagnetic Cr, Mn, and Pt layers and\nferromagnetic Co and Ni layers reveal how the orbital and spin currents compete\nor assist each other in determining the spin-orbit torques acting on the\nmagnetic layer. We further show how this interplay can be drastically modulated\nby introducing 4 f spacers between the nonmagnetic and magnetic layers. Gd and\nTb act as very efficient orbital-to-spin current converters, boosting the\nspin-orbit torques generated by Cr by a factor of 4 and reversing the sign of\nthe torques generated by Pt. To interpret our results, we present a generalized\ndrift-diffusion model that includes both spin and orbital Hall effects and\ndescribes their interconversion mediated by spin-orbit coupling.",
        "positive": "Conductance of Quantum Impurity Models from Quantum Monte Carlo: The conductance of two Anderson impurity models, one with two-fold and\nanother with four-fold degeneracy, representing two types of quantum dots, is\ncalculated using a world-line quantum Monte Carlo (QMC) method. Extrapolation\nof the imaginary time QMC data to zero frequency yields the linear conductance,\nwhich is then compared to numerical renormalization group results in order to\nassess its accuracy. We find that the method gives excellent results at low\ntemperature (T<Tk) throughout the mixed valence and Kondo regimes, but it is\nunreliable for higher temperature."
    },
    {
        "anchor": "Tunneling Aharonov-Bohm interferometer on helical edge states: We discuss transport through interferometer formed by helical edge states\ntunnel-coupled to metallic leads. We focus on the experimentally relevant case\nof relatively high temperature as compared to the level spacing and discuss a\nresponse of the setup to the external magnetic flux $\\phi$ (measured in units\nof flux quantum) piercing the area encompassed by edge states. We demonstrate\nthat tunneling conductance of the interferometer is structureless in ballistic\ncase but shows a sharp antiresonances, as a function of magnetic flux $\\phi$ -\nwith the period 1/2 - in the presence of magnetic impurity. We interpret the\nresonance behavior as a coherent enhancement of backward scattering off\nmagnetic impurity at integer and half-integer values of flux, which is\naccompanied by suppression of the effective scattering at other values of flux.\nBoth enhancement and suppression are due to the interference of processes with\nmultiple returns to magnetic impurity after a number of clockwise and\ncounterclockwise revolutions around setup. This phenomenon is similar to the\nwell-known weak-localization-induced enhancement of backscattering in\ndisordered systems. The quantum correction to the tunneling conductance is\nshown to be proportional to flux-dependent \"ballistic Cooperon\". The obtained\nresults can be used for flux-tunable control of the magnetic disorder in\nAharonov-Bohm interferometers built on helical edge states.",
        "positive": "Tunable Schottky barrier and high responsivity in graphene/Si-nanotip\n  optoelectronic device: We demonstrate tunable Schottky barrier height and record photo-responsivity\nin a new-concept device made of a single-layer CVD graphene transferred onto a\nmatrix of nanotips patterned on n-type Si wafer. The original layout, where\nnano-sized graphene/Si heterojunctions alternate to graphene areas exposed to\nthe electric field of the Si substrate, which acts both as diode cathode and\ntransistor gate, results in a two-terminal barristor with single-bias control\nof the Schottky barrier. The nanotip patterning favors light absorption, and\nthe enhancement of the electric field at the tip apex improves photo-charge\nseparation and enables internal gain by impact ionization. These features\nrender the device a photodetector with responsivity (3 A/W for white LED light\nat 3 mW/cm2 intensity) almost an order of magnitude higher than commercial\nphotodiodes. We extensively characterize the voltage and the temperature\ndependence of the device parameters and prove that the multi-junction approach\ndoes not add extra-inhomogeneity to the Schottky barrier height distribution.\nThis work represents a significant advance in the realization of graphene/Si\nSchottky devices for optoelectronic applications."
    },
    {
        "anchor": "Pure spin current transport in gallium doped zinc oxide: We study the flow of a pure spin current through zinc oxide by measuring the\nspin Hall magnetoresistance (SMR) in thin film trilayer samples consisting of\nbismuth-substituted yttrium iron garnet (Bi:YIG), gallium-doped zinc oxide\n(Ga:ZnO), and platinum. We investigate the dependence of the SMR magnitude on\nthe thickness of the Ga:ZnO interlayer and compare to a Bi:YIG/Pt bilayer. We\nfind that the SMR magnitude is reduced by almost one order of magnitude upon\ninserting a Ga:ZnO interlayer, and continuously decreases with increasing\ninterlayer thickness. Nevertheless, the SMR stays finite even for a\n$12\\;\\mathrm{nm}$ thick Ga:ZnO interlayer. These results show that a pure spin\ncurrent indeed can propagate through a several nm-thick degenerately doped zinc\noxide layer. We also observe differences in both the temperature and the field\ndependence of the SMR when comparing tri- and bilayers. Finally, we compare our\ndata to predictions of a model based on spin diffusion. This shows that\ninterface resistances play a crucial role for the SMR magnitude in these\ntrilayer structures.",
        "positive": "Giant spin-torque diode sensitivity at low input power in the absence of\n  bias magnetic field: Microwave detectors based on the spin-transfer torque diode effect are among\nthe key emerging spintronic devices. By utilizing the spin of electrons in\naddition to charge, they have the potential to overcome the theoretical\nperformance limits of their semiconductor (Schottky) counterparts, which cannot\noperate at low input power. Here, we demonstrate nanoscale microwave detectors\nexhibiting record-high detection sensitivity of 75400 mV mW$^{-1}$ at room\ntemperature, without any external bias fields, for input microwave power down\nto 10 nW. This sensitivity is 20x and 6x larger than state-of-the-art Schottky\ndiode detectors (3800 mV mW$^{-1}$) and existing spintronic diodes with >1000\nOe magnetic bias (12000 mV mW$^{-1}$), respectively. Micromagnetic simulations\nsupported by microwave emission measurements reveal the essential role of the\ninjection locking to achieve this sensitivity performance. The results enable\ndramatic improvements in the design of low input power microwave detectors,\nwith wide-ranging applications in telecommunications, radars, and smart\nnetworks."
    },
    {
        "anchor": "Observation of multiple flat bands and topological Dirac states in a new\n  titanium based slightly distorted kagome metal YbTi3Bi4: Kagome lattices have emerged as an ideal platform for exploring various\nexotic quantum phenomena such as correlated topological phases, frustrated\nlattice geometry, unconventional charge density wave orders, Chern quantum\nphases, superconductivity, etc. In particular, the vanadium based nonmagnetic\nkagome metals AV3Sb5 (A= K, Rb, and Cs) have seen a flurry of research interest\ndue to the discovery of multiple competing orders. Here, we report the\ndiscovery of a new Ti based kagome metal YbTi3Bi4 and employ angle-resolved\nphotoemission spectroscopy (ARPES), magnetotransport in combination with\ndensity functional theory calculations to investigate its electronic structure.\nWe reveal spectroscopic evidence of multiple flat bands arising from the kagome\nlattice of Ti with predominant Ti 3d character. Through our calculations of the\nZ2 indices, we have identified that the system exhibits topological\nnontriviality with surface Dirac cones at the Gamma point and a quasi\ntwo-dimensional Dirac state at the K point which is further confirmed by our\nARPES measured band dispersion. These results establish YbTi3Bi4 as a novel\nplatform for exploring the intersection of nontrivial topology, and electron\ncorrelation effects in this newly discovered Ti based kagome lattice.",
        "positive": "Properties and dynamics of meron topological spin textures in the\n  two-dimensional magnet CrCl3: Merons are nontrivial topological spin textures highly relevant for many\nphenomena in solid state physics. Despite their importance, direct observation\nof such vortex quasiparticles is scarce and has been limited to a few complex\nmaterials. Here we show the emergence of merons and antimerons in recently\ndiscovered two-dimensional (2D) CrCl3 at zero magnetic field. We show their\nentire evolution from pair creation, their diffusion over metastable domain\nwalls, and collision leading to large magnetic monodomains. Both quasiparticles\nare stabilized spontaneously during cooling at regions where in-plane magnetic\nfrustration takes place. Their dynamics is determined by the interplay between\nthe strong in-plane dipolar interactions and the weak out-of-plane magnetic\nanisotropy stabilising a vortex core within a radius of 8-10 nm. Our results\npush the boundary to what is currently known about non-trivial spin structures\nin 2D magnets and open exciting opportunities to control magnetic domains via\ntopological quasiparticles."
    },
    {
        "anchor": "Intersubband scattering in n-GaAs/AlGaAs wide quantum wells: Slow magnetooscilations of the conductivity are observed in a 75 nm wide\nquantum well at heating of the two-dimensional electrons by a high-intensity\nsurface acoustic wave. These magnetooscillations are caused by intersubband\nelastic scattering between the symmetric and asymmetric subbands formed due to\nan electrostatic barrier in the center of the quantum well. The tunneling\nsplitting between these subbands as well as the intersubband scattering rate\nare determined.",
        "positive": "Inverse design of reconfigurable piezoelectric topological phononic\n  plates: We present a methodology to perform inverse analysis on reconfigurable\ntopological insulators for flexural waves in plate-like structures. First the\nunit cell topology of a phononic plate is designed, which offers two-fold\ndegeneracy in the band structure by topology optimization. In the second step,\npiezoelectric patches bonded over the substrate plate are connected to an\nexternal circuit and used appropriately to break space inversion symmetry. The\nspace inversion symmetry breaking opens a topological band gap by mimicking\nquantum valley Hall effect. Numerical simulations demonstrate that the\ntopologically protected edge state exhibits wave propagation without\nbackscattering and is immune to disorders. Predominantly, the proposed idea\nenables real-time reconfigurability of the topological interfaces in waveguide\napplications."
    },
    {
        "anchor": "High-Throughput Calculations of Thermal Conductivity in Nanoporous\n  Materials: The Case of Half-Heusler Compounds: Achieving low thermal conductivity and good electrical properties is a\ncrucial condition for thermal energy harvesting materials. Nanostructuring\noffers a very powerful tool to address both requirements: in nanostructured\nmaterials, boundaries preferentially scatter phonons compared to electrons. The\nsearch for low-thermal-conductivity nanostructures is typically limited to\nmaterials with simple crystal structures, such as silicon, because of the\ncomplexity arising from modeling branch- and wave vector- dependent nanoscale\nheat transport. Using the phonon mean-free-path (MFP) dependent Boltzmann\ntransport equation, a model that overcomes this limitation, we compute thermal\ntransport in 75 nanoporous half-Heusler compounds for different pore sizes. We\ndemonstrate that the optimization of thermal transport in nanostructures should\ntake into account both bulk thermal properties and geometry-dependent phonon\nsuppression, two aspects that are typically engineered separately. In fact, our\nwork predicts that, given a set of bulk materials and a system geometry, the\nordering of the thermal conductivity of the nanostructure does not necessarily\nalign with that of the bulk: We show that what dictates thermal transport is\nthe interplay between the bulk MFP distribution and the nanostructuring length\nscale of the material. Finally, we derive a thermal transport model that\nenables fast systems screening within large bulk material repositories and a\ngiven geometry. Our study motivates the need for a holistic approach to\nengineering thermal transport and provides a method for high-throughput\nmaterials discovery.",
        "positive": "Thin films of a three-dimensional topological insulator in a strong\n  magnetic field: a microscopic study: The response of thin films of Bi$_2$Se$_3$ to a strong perpendicular magnetic\nfield is investigated by performing magnetic bandstructure calculations for a\nrealistic multi-band tight-binding model. Several crucial features of Landau\nquantization in a realistic three-dimensional topological insulator are\nrevealed. The $n=0$ Landau level is absent in ultra-thin films, in agreement\nwith experiment. In films with a crossover thickness of five quintuple layers,\nthere is a signature of the $n=0$ level, whose overall trend as a function of\nmagnetic field matches the established low-energy effective-model result.\nImportantly, we find a field-dependent splitting and a strong spin-polarization\nof the $n=0$ level which can be measured experimentally at reasonable field\nstrengths. Our calculations show mixing between the surface and bulk Landau\nlevels which causes the character of levels to evolve with magnetic field."
    },
    {
        "anchor": "Scanning gate microscopy mapping of edge current and branched electron\n  flow in a transition metal dichalcogenide nanoribbon and quantum point\n  contact: We study scanning gate microscopy (SGM) conductance mapping of a\n$\\mathrm{MoS}_2$ zigzag ribbon exploiting tight-binding and continuum models.\nWe show that, even though the edge modes of a pristine nanoribbon are robust to\nbackscattering on the potential induced by the tip, the conductance mapping\nreveals presence of both the edge modes and the quantized spin- and\nvalley-current carrying modes. By inspecting the electron flow from a split\ngate quantum point contact (QPC) we find that the mapped current flow allows to\ndetermine the nature of the quantization in the QPC as spin-orbit coupling\nstrength affects the number of branches in which the current exits the\nconstriction. The radial conductance oscillation fringes found in the\nconductance mapping reveal the presence of two possible wavevectors for the\ncharge carriers that correspond to spin and valley opposite modes. Finally, we\nshow that disorder induced valley mixing leads to a beating pattern in the\nradial fringes.",
        "positive": "Topological Phase Transitions of Generalized Brillouin Zone: It has been known that the bulk-boundary correspondence (BBC) of the\nnon-Hermitian skin effect is characterized by the topology of the complex\neigenvalue spectra, while the topology of the wave function gives rise to\nHermitian BBC with conventional boundary modes. In this work, we go beyond the\nknown description of the non-Hermitian topological phase by discovering a new\ntype of BBC that appears in generalized boundary conditions. The generalized\nBrillouin zone (GBZ) possesses non-trivial topological structures in the\nintermediate boundary condition between open and periodic boundary conditions.\nUnlike the conventional BBC, the topological phase transition is characterized\nby the generalized momentum touching of GBZ, which manifests as exceptional\npoints. As a realization of our proposal, we suggest the non-reciprocal\nKuramoto oscillator lattice, where the phase slips accompany the exceptional\npoints as a signature of such topological phase transition. Our work\nestablishes an understanding of non-Hermitian topological matter by\ncomplementing the non-Hermitian BBC as a general foundation of the\nnon-Hermitian topological systems."
    },
    {
        "anchor": "Fundamental Limits to Moore's Law: The theoretical and practical aspects of the fundamental, ultimate, physical\nlimits to scaling, or Moore-s law, is presented.",
        "positive": "Anomalous spin Hall angle of a metallic ferromagnet determined by a\n  multiterminal spin injection/detection device: We report on the determination of the anomalous spin Hall angle in the\nferromagnetic metal alloy cobalt-iron (Co$_{25}$Fe$_{75}$, CoFe). This is\naccomplished by measuring the spin injection/detection efficiency in a\nmultiterminal device with nanowires of platinum (Pt) and CoFe deposited onto\nthe magnetic insulator yttrium iron garnet (Y$_3$Fe$_5$O$_{12}$, YIG). Applying\na spin-resistor model to our multiterminal spin transport data, we determine\nthe magnon conductivity in YIG, the spin conductance at the YIG/CoFe interface\nand finally the anomalous spin Hall angle of CoFe as a function of its spin\ndiffusion length in a single device. Our experiments clearly reveal a negative\nanomalous spin Hall angle of the ferromagnetic metal CoFe, but a vanishing\nordinary spin Hall angle. This is in contrast to the results reported for the\nferromagnetic metals Co and permalloy."
    },
    {
        "anchor": "Time reversal of pseudo-spin 1/2 degrees of freedom: We show that pseudo-spin 1/2 degrees of freedom can be categorized in two\ntypes according to their behavior under time reversal. One type exhibits the\nproperties of ordinary spin whose three Cartesian components are all odd under\ntime reversal. For the second type, only one of the components is odd while the\nother two are even. We discuss several physical examples for this second type\nof pseudo-spin and highlight observable consequences that can be used to\ndistinguish it from ordinary spin.",
        "positive": "Quantum superposition of a single microwave photon in two different\n  \"colour\" states: The ability to coherently couple arbitrary harmonic oscillators in a\nfully-controlled way is an important tool to process quantum information.\nCoupling between quantum harmonic oscillators has previously been demonstrated\nin several physical systems by use of a two-level system as a mediating\nelement. Direct interaction at the quantum level has only recently been\nrealized by use of resonant coupling between trapped ions. Here we implement a\ntunable direct coupling between the microwave harmonics of a superconducting\nresonator by use of parametric frequency conversion. We accomplish this by\ncoupling the mode currents of two harmonics through a superconducting quantum\ninterference device (SQUID) and modulating its flux at the difference (~ 7 GHz)\nof the harmonic frequencies. We deterministically prepare a single-photon Fock\nstate and coherently manipulate it between multiple modes, effectively\ncontrolling it in a superposition of two different \"colours\". This parametric\ninteraction can be described as a beam-splitter-like operation that couples\ndifferent frequency modes. As such, it could be used to implement linear\noptical quantum computing protocols on-chip."
    },
    {
        "anchor": "Engineering ultrafast spin currents and terahertz transients by magnetic\n  heterostructures: In spin-based electronics, information is encoded by the spin state of\nelectron bunches. Processing this information requires the controlled transport\nof spin angular momentum through a solid, preferably at frequencies reaching\nthe so far unexplored terahertz (THz) regime. Here, we demonstrate, by\nexperiment and theory, that the temporal shape of femtosecond spin-current\nbursts can be manipulated by using specifically designed magnetic\nheterostructures. A laser pulse is employed to drive spins from a ferromagnetic\nFe thin film into a nonmagnetic cap layer that has either low (Ru) or high (Au)\nelectron mobility. The resulting transient spin current is detected by means of\nan ultrafast, contactless amperemeter based on the inverse spin Hall effect\nthat converts the spin flow into a THz electromagnetic pulse. We find that the\nRu cap layer yields a considerably longer spin-current pulse because electrons\nare injected in Ru d states that have a much smaller mobility than Au sp\nstates. Thus, spin current pulses and the resulting THz transients can be\nshaped by tailoring magnetic heterostructures, which opens the door for\nengineering high-speed spintronic devices as well as broadband THz emitters in\nparticular covering the elusive range from 5 to 10THz.",
        "positive": "Effect of spatial dispersion on the spectrum of inter-edge\n  magnetoplasmons in the two-dimensional heterogeneous system: The present paper is devoted to the theoretical study of the spectrum of\nlow-frequency electronic density oscillations running along the boundary of two\ncontacting two-dimensional electronic systems in the perpendicular magnetic\nfield. For the first time, such waves were predicted in the Institute of\nRadio-engineering and Electronics of RAS (V.A. Volkov, S.A. Mikhailov, 1992),\nstudied experimentally in the papers of foreign investigations and called\ninter-edge magnetoplasmons (IEMP). When the two-dimensional system is finite\nand has the half-plane shape, the internal boundary becomes external and these\nplasmons go over into the well-known edge magnetoplasmons. The existing theory\nof edge and inter-edge magnetoplasmons is built with the neglect of spatial\ndispersion of the conductivity. Here we attempt to derive and analyze the IEMP\ndispersion equation involving spatial dispersion of conductivity. The inner\nboundary is assumed to be a straight line at which the electron concentration\nchanges weakly but stepwise. The jump of the diagonal conductivity is\nconsidered small compared with that of the Hall magnetoconductivity. The IEMP\nfrequency is small compared with the cyclotron frequency. The IEMP frequency as\na function of wavevector oscillates with the period determined by a ratio of\nelectron cyclotron radius to the plasmon wavelength. For long wavelengths, the\nIEMP dispersion curve coincides with the known result."
    },
    {
        "anchor": "Systematic motion of magnetic domain walls in notched nanowires under\n  ultra-short current pulses: The precise manipulation of transverse magnetic domain walls in\nfinite/infinite nanowires with artificial defects under the influence of very\nshort spin-polarized current pulses is investigated. We show that for a\nclassical $3d$ ferromagnet material like Nickel, the exact positioning of the\ndomain walls at room temperature is possible only for pulses with very short\nrise and fall time that move the domain wall reliably to nearest neighboring\npinning position. The influence of the shape of the current pulse and of the\ntransient effects on the phase diagram current-pulse length are discussed. We\nshow that large transient effects appear even when $\\alpha$=$\\beta$, below a\ncritical value, due to the domain wall distortion caused by the current pulse\nshape and the presence of the notches. The transient effects can oppose or\namplify the spin-transfer torque (STT), depending on the ratio $\\beta/\\alpha$.\nThis enlarges the physical comprehension of the DW motion under STT and opens\nthe route to the DW displacement in both directions with unipolar currents.",
        "positive": "Approximate Solutions of a Kinetic Theory for Graphene: The effective mass approximation is analysed in a nonperturbative kinetic\ntheory approach to strong field excitations in graphene [1,2]. This problem is\nhighly actual for the investigation of quantum radiation from graphene [3],\nwhere the collision integrals in the photon kinetic equation are rather\ncomplicated functionals of the distribution functions of the charge carriers.\nThese functions are needed in the explicit analytical definition as solutions\nof the kinetic equations for the electron-hole excitations. In the present work\nit is shown that the suggested approach is rather effective in a certain range\nof parameters for the pulse of an external electromagnetic field. For example,\nthe applicability condition of the approximation in the case of a harmonic\nfield is $\\hbar \\omega^2 / (\\sqrt{2} e E_0 v_F) < 1$, were $v_F$ is the Fermi\nvelocity. In the standard massive quantum electrodynamics the usability of the\nanalogical approximation is very narrow."
    },
    {
        "anchor": "Internal structure of nanoparticles of Al generated by laser ablation in\n  liquid ethanol: Al NPs are synthesized by laser ablation of a bulk Al target immersed into\nliquid ethanol saturated with hydrogen at atmospheric pressure. The\nnanoparticles possess a well-distinguished core-shell structure. High\nResolution Transmission Electron Microscopy shows several layers inside the Al\nnanoparticle: oxide layer, amorphous Al, single crystal Al, and a cavity in the\ncenter. Formation of the cavity is attributed to the sharp increase of hydrogen\ndissolution in Al upon its melting and its eventual release after the\nsolidification.",
        "positive": "Phonon Renormalization in Reconstructed MoS$_2$ Moir\u00e9 Superlattices: In moir\\'e crystals formed by stacking van der Waals (vdW) materials,\nsurprisingly diverse correlated electronic phases and optical properties can be\nrealized by a subtle change in the twist angle. Here, we discover that phonon\nspectra are also renormalized in MoS$_2$ twisted bilayers, adding a new\nperspective to moir\\'e physics. Over a range of small twist angles, the phonon\nspectra evolve rapidly due to ultra-strong coupling between different phonon\nmodes and atomic reconstructions of the moir\\'e pattern. We develop a new\nlow-energy continuum model for phonons that overcomes the outstanding challenge\nof calculating properties of large moir\\'e supercells and successfully captures\nessential experimental observations. Remarkably, simple optical spectroscopy\nexperiments can provide information on strain and lattice distortions in\nmoir\\'e crystals with nanometer-size supercells. The newly developed theory\npromotes a comprehensive and unified understanding of structural, optical, and\nelectronic properties of moir\\'e superlattices."
    },
    {
        "anchor": "Valley current filtering and reversal by parallel side contacted\n  armchair nanotubes: The intertube conductance $G$ of the parallel side contacted armchair\nnanotubes is calculated by Landauer's formula as a function of the Fermi level\n$E$. When the intertube difference in the dope strength is large enough, a\nresonant peak dominant over the others appears in the $E$-$G$ curve. The\noverlap length and the interlayer configuration do not influence the resonant\nenergy. The intervalley transmission at the resonant peak works as a reverser\nand a filter of the valley current.",
        "positive": "Novel Theory for Topological Structure of Vortices in BEC: By making use of the $\\phi $-mapping topological current theory, a novel\nexpression of $\\nabla \\times \\vec{V}$ in BEC is obtained, which reveals the\ninner topological structure of vortex lines characterized by Hopf indices and\nBrouwer degrees. This expression is just that formula Landau and Feynman\nexpected to find out long time ago. In the case of superconductivity, the\ndecomposition theory of U(1) gauge potential in terms of the condensate wave\nfunction gives a rigorous proof of London assumption, and shows that each\nvortex line should carry a quantized flux. The $\\phi $-mapping topological\ncurrent theory of $\\nabla \\times \\vec{V}$ can also gives a precise bifurcation\ntheory of vortex lines in BEC."
    },
    {
        "anchor": "Plasmonic Hot Spots in Triangular Tapered Graphene Microcrystals: Recently, plasmons in graphene have been observed experimentally using\nscattering scanning near-field optical microscopy. In this paper, we develop a\nsimplified analytical approach to describe the behavior in triangular samples.\nReplacing Coulomb interaction by a short-range one reduces the problem to a\nHelmholtz equation, amenable to analytical treatment. We demonstrate that even\nwith our simplifications, the system still exhibits the key features seen in\nthe experiment.",
        "positive": "Tuning the nonlinear dispersive coupling of nanomechanical string\n  resonators: We investigate nonlinear dispersive mode coupling between the flexural in-\nand out-of-plane modes of two doubly clamped, nanomechanical silicon nitride\nstring resonators. As the amplitude of one mode transitions from the linear\nresponse regime into the nonlinear regime, we find a frequency shift of two\nother modes. The resonators are strongly elastically coupled via a shared\nclamping point and can be tuned in and out of resonance dielectrically, giving\nrise to multimode avoided crossings. When the modes start hybridizing, their\npolarization changes. This affects the nonlinear dispersive coupling in a\nnon-trivial way. We propose a theoretical model to describe the dependence of\nthe dispersive coupling on the mode hybridization."
    },
    {
        "anchor": "Dynamics of energy transport and entropy production in ac-driven quantum\n  electron systems: We analyze the time-resolved energy transport and the entropy production in\nac-driven quantum coherent electron systems coupled to multiple reservoirs at\nfinite temperature. At slow driving we formulate the first and second laws of\nthermodynamics valid at each instant of time. We identify heat fluxes flowing\nthough the different pieces of the device and emphasize the importance of the\nenergy stored in the contact and central regions for the second law of\nthermodynamics to be instantaneously satisfied. In addition, we discuss\nconservative and dissipative contributions to the heat flux and to the entropy\nproduction as a function of time. We illustrate these ideas with a simple model\ncorresponding to a driven level coupled to two reservoirs with different\nchemical potentials.",
        "positive": "Thermoelectric characterization of the Kondo resonance in nanowire\n  quantum dots: We experimentally verify hitherto untested theoretical predictions about the\nthermoelectric properties of Kondo correlated quantum dots (QDs). The specific\nconditions required for this study are obtained by using QDs epitaxially grown\nin nanowires, combined with a recently developed method for controlling and\nmeasuring temperature differences at the nanoscale. This makes it possible to\nobtain data of very high quality both below and above the Kondo temperature,\nand allows a quantitative comparison with theoretical predictions.\nSpecifically, we verify that Kondo correlations can induce a polarity change of\nthe thermoelectric current, which can be reversed either by increasing the\ntemperature or by applying a magnetic field."
    },
    {
        "anchor": "Universal Majorana thermoelectric noise: Thermoelectric phenomena resulting from an interplay between particle flows\ninduced by electric fields and temperature inhomogeneities are extremely\ninsightful as a tool providing substantial knowledge about the microscopic\nstructure of a given system. Tuning, e.g., parameters of a nanoscopic system\ncoupled via tunneling mechanisms to two contacts one may achieve various\nsituations where the electric current induced by an external bias voltage\ncompetes with the electric current excited by the temperature difference of the\ntwo contacts. Even more exciting physics emerges when the system's electronic\ndegrees freedom split to form Majorana fermions which make the thermoelectric\ndynamics universal. Here we propose revealing this unique universal signatures\nof Majorana fermions in strongly nonequilibrium quantum dots via noise of the\nthermoelectric transport beyond linear response. It is demonstrated that\nwhereas mean thermoelectric quantities are only universal at large bias\nvoltages, the noise of the electric current excited by an external bias voltage\nand the temperature difference of the contacts is universal at any bias\nvoltage. We provide truly universal, i.e. independent of the system's\nparameters, thermoelectric ratios between nonlinear response coefficients of\nthe noise and mean current at large bias voltages where experiments may easily\nbe performed to uniquely detect these truly universal Majorana thermoelectric\nsignatures.",
        "positive": "Anomalous thermoelectric properties of a Floquet topological insulator\n  with spin momentum non-orthogonality: The spin momentum non-orthogonality in 3D topological insulators leads to\nmodification of the spin texture and brings in an out-of-plane spin\npolarization component. Apart from spin texture, the anomalous thermoelectric\nproperties of these materials are worth studying. In this paper, we have\npointed out that the off resonant light used to irradiate the surface states,\ninduces a gap, which becomes momentum dependent due to the presence of\nnon-orthogonal terms in the Hamiltonian. Importantly, to maintain the off\nresonant condition of light, the momentum value should satisfy a bound.\nFurthermore, the momentum dependent gap causes a topological transition at\nhigher value of momentum, which is important to analyse the unusual double peak\nstructure of the Nernst and electrical conductivities."
    },
    {
        "anchor": "SU(2) instantons with boundary jumps and spin tunneling in magnetic\n  molecules: Coherent state path integrals are shown in general to contain instantons with\njumps at the boundaries, i.e., with boundary points lying outside classical\nparameter or phase space. As an example, the magnetic molecule Fe_8 is studied\nusing a realistic Hamiltonian, and instanons with jumps are shown to dominate\nbeyond a certain external magnetic field. An approximate formula is found for\nthe fields where ground state tunneling is quenched in this molecule.",
        "positive": "Temperature dependence of spin-model parameters in antiferromagnets: The temperature dependence of mesoscopic spin-model parameters is derived in\ntwo-sublattice antiferromagnetically aligned systems based on Green's function\ntheory. It is found that transversal spin correlations decrease the anisotropy\nterms while increasing the Heisenberg and Dzyaloshinsky--Moriya exchange\ninteractions and the latter's contribution to the anisotropy. The obtained\ntemperature dependences show quantitative agreement with the results for\nferromagnets, and they also agree well with numerical atomistic simulations\nwhich treat the spin correlations without approximations. Possible applications\nof the results in multiscale modelling are discussed."
    },
    {
        "anchor": "Transmissions in Graphene through Double Barriers and Periodic Potential: Transmission of Dirac fermions through a chip of graphene under the effect of\nmagnetic field and a time vibrating double barrier with frequency $w$ is\ninvestigated. Quantum interference within the oscillating barrier has an\nimportant effect on quasi-particles tunneling. A combination of both a time\ndependent potential and a magnetic field generate physical states whose energy\nis double quantified by the pair of integers $(n, l)$ with high degeneracy. The\nlarge number of modes that exist in the energy spectrum presents a colossal\ndifficulty in numerical computations. Thus we were obliged to make a truncation\nand limit ourselves to the central $(n = 0)$ and two adjacent side band ($n=\\pm\n1$).",
        "positive": "Anomalous dissipation mechanism and Hall quantization limit in\n  polycrystalline graphene grown by chemical vapor deposition: We report on the observation of strong backscattering of charge carriers in\nthe quantum Hall regime of polycrystalline graphene grown by chemical vapor\ndeposition, which alters the accuracy of the Hall resistance quantization. The\ntemperature and magnetic field dependence of the longitudinal conductivity\nexhibits unexpectedly smooth power law behaviors, which are incompatible with a\ndescription in terms of variable range hopping or thermal activation, but\nrather suggest the existence of extended or poorly localized states at energies\nbetween Landau levels. Such states could be caused by the high density of line\ndefects (grain boundaries and wrinkles) that cross the Hall bars, as revealed\nby structural characterizations. Numerical calculations confirm that\nquasi-one-dimensional extended non-chiral states can form along such line\ndefects and short-circuit the Hall bar chiral edge states."
    },
    {
        "anchor": "Non-Abelian BF theory for 2+1 dimensional topological states of matter: We present a field theoretical analysis of the 2+1 dimensional BF model with\nboundary in the Abelian and the non-Abelian case based on the Symanzik's\nseparability condition. In both cases on the edges we obtain Ka\\v{c}--Moody\nalgebras with opposite chiralities reflecting the time reversal invariance of\nthe theory. While the Abelian case presents an apparent arbitrariness in the\nvalue of the central charge, the physics on the boundary of the non-Abelian\ntheory is completely determined by time reversal and gauge symmetry. The\ndiscussion of the non-Abelian BF model shows that time reversal symmetry on the\nboundary implies the existence of counter-propagating chiral currents.",
        "positive": "Features of phonon scattering by a spherical pore: molecular dynamics\n  insight: There is still a gap in understanding phonons scattering by geometrical\ndefects at the nanoscale, and it remains a significant challenge for heat\ntransfer management in nanoscale devices and systems. In this study, we aim to\nexplore the characteristics of phonon scattering by a single pore to gain\ninsights into thermal transport in nanostructures. The paper outlines a\nmethodology for assessing the spatial distribution of the magnitude of the\nradial, azimuthal, and polar components of the velocity of scattered phonons by\na spherical pore. We demonstrated that the size parameter, commonly employed in\nelectromagnetic wave scattering theory, is vital in determining the scattering\nregime. Specifically, we show that calculated scattering efficiency has the\nsame pattern as one commonly obtained in classical wave scattering theory.\nHowever, we found that crystallographic directions are pivotal in shaping the\nscattering patterns, especially in the regions where scattering patterns are\ndefined by the Mie resonances. This observation holds significance in\nunderstanding the influence of phonon coherence on thermal transport in\nnanostructured materials."
    },
    {
        "anchor": "Observation of inter-Landau-level quantum coherence in semiconductor\n  quantum wells: Using three-pulse four-wave-mixing femtosecond spectroscopy, we excite a\nnon-radiative coherence between the discrete Landau levels of an undoped\nquantum well and study its dynamics. We observe quantum beats that reflect the\ntime evolution of the coherence between the two lowest Landau level\nmagnetoexcitons. We interpret our observations using a many-body theory and\nfind that the inter Landau level coherence decays with a new time constant,\nsubstantially longer than the corresponding interband magnetoexciton dephasing\ntimes. Our results indicate a new intraband excitation dynamics that cannot be\ndescribed in terms of uncorrelated interband excitations.",
        "positive": "Magnetic structures on locally inverted interlayer coupling region of\n  bilayer magnetic system: We investigate the magnetic structures in a bilayer magnetic system with the\nlocally inverted interlayer coupling region using Monte Carlo simulation.\nStabilization of multiple magnetic structures including the magnetic skyrmion\nis possible in the locally inverted interlayer coupling region. Various factors\nsuch as the region area, anisotropy, interlayer coupling strength, and exchange\ncoupling strength affects the properties of the structures including its size\nand chirality. We obtain conditions for their stabilization and for the\nmagnetic structural transitions. Dzyaloshinskii-Moriya interaction (DMI) and\nthe dipolar interaction play a prominent role as they enhance the formation and\nthe stability of structures significantly. An asymmetric feature can arise from\nthe broken inversion symmetry in the structure formation, and it gives an\ninterfacial DMI, which stabilizes the skyrmion. It is realized that the dipole\ninteraction also acts as an effective interfacial DMI in the system."
    },
    {
        "anchor": "Competing \u03bd= 5/2 fractional quantum Hall states in confined geometry: Some theories predict that the filling factor 5/2 fractional quantum Hall\nstate can exhibit non-Abelian statistics, which makes it a candidate for\nfault-tolerant topological quantum computation. Although the non-Abelian\nPfaffian state and its particle-hole conjugate, the anti-Pfaffian state, are\nthe most plausible wave functions for the 5/2 state, there are a number of\nalternatives with either Abelian or non-Abelian statistics. Recent experiments\nsuggest that the tunneling exponents are more consistent with an Abelian state\nrather than a non-Abelian state. Here, we present edge-current-tunneling\nexperiments in geometrically confined quantum point contacts, which indicate\nthat Abelian and non-Abelian states compete at filling factor 5/2. Our results\nare consistent with a transition from an Abelian state to a non-Abelian state\nin a single quantum point contact when the confinement is tuned. Our\nobservation suggests that there is an intrinsic non-Abelian 5/2 ground state,\nbut that the appropriate confinement is necessary to maintain it. This\nobservation is important not only for understanding the physics of the 5/2\nstate, but also for the design of future topological quantum computation\ndevices.",
        "positive": "Quantum Hall Effects: These lecture notes yield an introduction to quantum Hall effects both for\nnon-relativistic electrons in conventional 2D electron gases (such as in\nsemiconductor heterostructures) and relativistic electrons in graphene. After a\nbrief historical overview in chapter 1, we discuss in detail the kinetic-energy\nquantisation of non-relativistic and the relativistic electrons in a strong\nmagnetic field (chapter 2). Chapter 3 is devoted to the transport\ncharacteristics of the integer quantum Hall effect, and the basic aspects of\nthe fractional quantum Hall effect are described in chapter 4. In chapter 5, we\nbriefly discuss several multicomponent quantum Hall systems, namely the quantum\nHall ferromagnetism, bilayer systems and graphene that may be viewed as a\nfour-component system."
    },
    {
        "anchor": "Skyrmion-number dependence of spin-transfer torque on magnetic bubbles: We theoretically study the skyrmion-number dependence of spin-transfer torque\nacting on magnetic bubbles. The skymrion number of magnetic bubbles can take\nany integer value depending on the magnetic profile on its circumference and\nthe size of the bubble. We find that the transverse motion of a bubble with\nrespect to the charge current is greatly suppressed as the absolute value of\nskyrmion number departs from unity, whereas the longitudinal motion is less\nsensitive.",
        "positive": "Modelling ultra-fast nanoparticle melting with the Maxwell-Cattaneo\n  equation: The role of thermal relaxation in nanoparticle melting is studied using a\nmathematical model based on the Maxwell--Cattaneo equation for heat conduction.\nThe model is formulated in terms of a two-phase Stefan problem. We consider the\ncases of the temperature profile being continuous or having a jump across the\nsolid-liquid interface. The jump conditions are derived from the\nsharp-interface limit of a phase-field model that accounts for variations in\nthe thermal properties between the solid and liquid. The Stefan problem is\nsolved using asymptotic and numerical methods. The analysis reveals that the\nFourier-based solution can be recovered from the classical limit of zero\nrelaxation time when either boundary condition is used. However, only the jump\ncondition avoids the onset of unphysical `supersonic' melting, where the speed\nof the melt front exceeds the finite speed of heat propagation. These results\nconclusively demonstrate that the jump condition, not the continuity condition,\nis the most suitable for use in models of phase change based on the\nMaxwell--Cattaneo equation. Numerical investigations show that thermal\nrelaxation can increase the time required to melt a nanoparticle by more than a\nfactor of ten. Thus, thermal relaxation is an important process to include in\nmodels of nanoparticle melting and is expected to be relevant in other rapid\nphase-change processes."
    },
    {
        "anchor": "Linear-response magnetoresistance effects in chiral systems: The chirality-induced spin selectivity (CISS) effect enables the detection of\nchirality as electrical charge signals. It is often studied using a\ntwo-terminal circuit geometry where a ferromagnet is connected to a chiral\ncomponent, and a change of electrical resistance is reported upon magnetization\nreversal. This is however not expected in the linear response regime because of\ncompensating reciprocal processes, limiting the interpretation of experimental\nresults. Here we show that magnetoresistance effects can indeed appear even in\nthe linear response regime, either by changing the magnitude or the direction\nof the magnetization or an applied magnetic field. We illustrate this in a\nspin-valve device and in a chiral thin film as the CISS-induced Hanle\nmagnetoresistance (CHMR) effect. This effect helps to distinguish\nspin-transport-related effects from other effects, and can thereby provide\nfurther insight into the origin of CISS.",
        "positive": "Effect of screening on shot noise in diffusive mesoscopic conductors: Shot noise in diffusive mesoscopic conductors, at finite observation\nfrequencies $\\omega $ (comparable to the reciprocal Thouless time\n$\\tau_T^{-1}$), is analyzed with an account of screening. At low frequencies,\nthe well-known result $S_I(\\omega)=2eI/3$ is recovered. This result is valid at\narbitrary $\\omega \\tau_T$ for wide conductors longer than the screening length.\nHowever, at least for two very different systems, namely, wide and short\nconductors, and thin conductors over a close ground plane, noise approaches a\ndifferent fundamental level, $S_I(\\omega) = eI$, at $\\omega \\tau _T\\gg 1$."
    },
    {
        "anchor": "Influence of Disorder on Electron-Hole Pair Condensation in Graphene\n  Bilayers: Graphene bilayers can condense into a state with spontaneous interlayer phase\ncoherence that supports dissipationless counterflow supercurrents. Here we\naddress the influence of disorder on the graphene bilayer mean-field and\nKosterlitz-Thouless critical temperatures and report on a simple criteria for\nthe survival of pair condensation.",
        "positive": "Modified spin-orbit couplings in uniaxially strained graphene: Intrinsic and Rashba spin-orbit interactions in strained graphene is studied\nwithin the tight-binding (TB) approach. Dependence of Slater-Koster (SK)\nparameters of graphene on strain are extracted by fitting the \\emph{ab initio}\nband structure to the TB results. A generalized low-energy effective\nHamiltonian in the presence of spin-orbit couplings is proposed for strained\ngraphene subjected to an external perpendicular electric field. Dependence of\nthe modified Rashba strength and other parameters of effective Hamiltonian on\nthe strain and electric field are calculated. In order to analyze the influence\nof the applied strain on the electronic properties of the graphene, one must\ntake into account the lattice deformation, modifications of the hopping\namplitudes and shift of the Dirac points. We find that using the strain it is\npossible to control the strength of Rashba and intrinsic spin-orbit couplings\nas well as energy gap at the shifted Dirac points. Meanwhile, the strain\nslightly modifies the topology of low-energy dispersion around the Dirac\npoints. We describe the SOCs induced energy splitting as a function of strain."
    },
    {
        "anchor": "Phonon mediated drag in double layer two dimensional electron systems: Experiments studying phonon mediated drag in the double layer two dimensional\nelectron gas system are reported. Detailed measurements of the dependence of\ndrag on temperature, layer spacing, density ratio, and matched density are\ndiscussed. Comparisons are made to theoretical results [M. C. Bonsager et al.,\nPhys. Rev. B 57, 7085 (1998)] which propose the existence of a new coupled\nelectron-phonon collective mode. The layer spacing and density dependence at\nmatched densities for samples with layer spacings below 2600 A do not support\nthe existence of this mode, showing behavior expected for independent electron\nand phonon systems. The magnitude of the drag, however, suggests the alternate\nlimit; one in which electrons and phonons are strongly coupled. The results for\nstill larger layer spacing show significant discrepancies with the behavior\nexpected for either limit.",
        "positive": "Strong Charge Fluctuations in the Single-Electron Box: A Quantum Monte\n  Carlo Analysis: We study strong electron tunneling in the single-electron box, a small\nmetallic island coupled to an electrode by a tunnel junction, by means of\nquantum Monte Carlo simulations. We obtain results, at arbitrary tunneling\nstrength, for the free energy of this system and the average charge on the\nisland as a function of an external bias voltage. In much of the parameter\nrange an extrapolation to the ground state is possible. Our results for the\neffective charging energy for strong tunneling are compared to earlier -- in\npart controversial -- theoretical predictions and Monte Carlo simulations."
    },
    {
        "anchor": "Two-Dimensional Spectroscopy of Two-Dimensional Materials: In this work we provide an exact and efficient numerical approach to simulate\nmulti-time correlation functions in the Mahan-Nozi\\`{e}res-De Dominicis model,\nwhich crudely mimics the spectral properties of doped two-dimensional\nsemiconductors such as monolayer transition metal dichalcogenides. We apply\nthis approach to study the coherent two-dimensional electronic spectra of the\nmodel. We show that several experimentally observed phenomena, such as peak\nasymmetry and coherent oscillations in the waiting-time dependence of the\ntrion-exciton cross peaks of the two-dimensional rephasing spectrum, emerge\nnaturally in our approach. Additional features are also present which find no\ncorrespondence with experimentally expected behavior. We trace these features\nto the infinite hole mass property of the model. We use this understanding to\nconstruct an efficient approach which filters out configurations associated\nwith the lack of exciton recoil, enabling the connection to previous work and\nproviding a route to the construction of realistic two-dimensional spectra over\na broad doping range in two-dimensional semiconductors.",
        "positive": "Experimental observation of thermal fluctuations in single\n  superconducting Pb nanoparticles through tunneling measurements: An important question in the physics of superconducting nanostructures is the\nrole of thermal fluctuations on superconductivity in the zero-dimensional\nlimit. Here, we probe the evolution of superconductivity as a function of\ntemperature and particle size in single, isolated Pb nanoparticles. Accurate\ndetermination of the size and shape of each nanoparticle makes our system a\ngood model to quantitatively compare the experimental findings with theoretical\npredictions. In particular, we study the role of thermal fluctuations (TF) on\nthe tunneling density of states (DOS) and the superconducting energy gap (D) in\nthese nanoparticles. For the smallest particles, h < 13nm, we clearly observe a\nfinite energy gap beyond Tc giving rise to a \"critical region\". We show\nexplicitly through quantitative theoretical calculations that these deviations\nfrom mean-field predictions are caused by TF. Moreover, for T << Tc, where TF\nare negligible, and typical sizes below 20 nm, we show that D gradually\ndecreases with reduction in particle size. This result is described by a\ntheoretical model that includes finite size effects and zero temperature\nleading order corrections to the mean field formalism."
    },
    {
        "anchor": "Examining the validity of the two-dimensional conical model to describe\n  the three-dimensional ZrTe5: Understanding the low-energy excitation state in three-dimensional layered\ncompound ZrTe5 remains a challenging problem in the study of novel topological\nmaterials. Recently, a two-dimensional conical model was proposed to explain\nthe experimental optical spectroscopy in the 3D ZrTe5, Martino et al. [Phys.\nRev. Lett. 122, 217402 (2019)]. Motivated by this work, in this paper, we\nperform a systematic theoretical study on the optical conductivity of this\nmodel in both cases without and with an external magnetic field to further\ndemonstrate the validity of this model and to recover new physics.We find that\nthere exist completely different characteristics for optical conductivity along\ndifferent directions, due to anisotropic low-energy excitations in this\ntwo-dimensional conical model. Specifically, for the interband optical\nconductivity, we find asymptotic dependence on the optical frequency as\nRe(\\sigma_x)\\sim\\omega^{1/2} and Re(\\sigma_z)\\sim{\\omega}^{3/2}, which are\nuniversal both in the gapped insulator phase and Weyl semimetal phase. For the\nmagneto-optical conductivity, on the contrary, Re(\\sigma^B_{x/z}) shows\ndistinct signatures in the gapped insulator phase and Weyl semimetal phase,\nwhich can help distinguish the two phases. Our results, to be verified in\nfuture experiments, could provide more insights into the understanding of the\ntopological nature of ZrTe5.",
        "positive": "Tunable optical Aharonov-Bohm effect in a semiconductor quantum ring: By applying an electric field perpendicular to a semiconductor quantum ring\nwe show that it is possible to modify the single particle wave function between\nquantum dot (QD)-like to ring-like. The constraints on the geometrical\nparameters of the quantum ring to realize such a transition are derived. With\nsuch a perpendicular electric field we are able to tune the Aharanov-Bohm (AB)\neffect for both single particles and for excitons. The tunability is in both\nthe strength of the AB-effect as well as in its periodicity. We also\ninvestigate the strain induce potential inside the self assembled quantum ring\nand the effect of the strain on the AB effect."
    },
    {
        "anchor": "Resonant and inelastic Andreev tunneling observed on a carbon nanotube\n  quantum dot: We report the observation of two fundamental sub-gap transport processes\nthrough a quantum dot (QD) with a superconducting contact. The device consists\nof a carbon nanotube contacted by a Nb superconducting and a normal metal\ncontact. First, we find a single resonance with position, shape and amplitude\nconsistent with the theoretically predicted resonant Andreev tunneling (AT)\nthrough a single QD level. Second, we observe a series of discrete replicas of\nresonant AT at a separation of $\\sim145\\,\\mu$eV, with a gate, bias and\ntemperature dependence characteristic for boson-assisted, inelastic AT, in\nwhich energy is exchanged between a bosonic bath and the electrons. The\nmagnetic field dependence of the replica's amplitudes and energies suggest that\ntwo different bosons couple to the tunnel process.",
        "positive": "Nonlocal Anomalous Hall Effect: The anomalous Hall effect is deemed to be a unique transport property of\nferromagnetic metals, caused by the concerted action of spin polarization and\nspin-orbit coupling. Nevertheless, recent experiments have shown that the\neffect also occurs in a nonmagnetic metal (Pt) in contact with a magnetic\ninsulator (yttrium iron garnet (YIG)), even when precautions are taken to\nensure there is no induced magnetization in the metal. We propose a theory of\nthis effect based on the combined action of spin-dependent scattering from the\nmagnetic interface and the spin Hall effect in the bulk of the metal. At\nvariance with previous theories, we predict the effect to be of first order in\nthe spin-orbit coupling, just as the conventional anomalous Hall effect -- the\nonly difference being the spatial separation of the spin orbit interaction and\nthe magnetization. For this reason we name this effect \\textit{nonlocal\nanomalous Hall effect} and predict that its sign will be determined by the sign\nof the spin Hall angle in the metal. The AH conductivity that we calculate from\nour theory is in good agreement with the measured values in Pt/YIG structures."
    },
    {
        "anchor": "Controllable excitation of quasi-linear and bullet modes in a spin-Hall\n  nano-oscillator: We experimentally demonstrate that both quasi-linear and nonlinear\nself-localized bullet modes of magnetization auto-oscillation can be excited by\ndc current in the nano-gap spin Hall nano-oscillator, by utilizing the geometry\nwith an extended gap. The quasi-linear mode is stable at low driving currents,\nwhile the bullet mode is additionally excited at larger currents, and becomes\nincreasingly dominant with increasing current. Time-resolved measurements show\nthat the formation of the bullet mode is delayed relative to the quasi-linear\nmode by up to 100 nanoseconds, demonstrating that the mechanisms of the\nformation of these modes are fundamentally different. We discuss the\nrelationship between the observed behaviors and the formation of an unstable\nnonlinear magnon condensate.",
        "positive": "Nucleation and growth of metal whiskers: The existence of metal whiskers is attributed to the energy gain due to\nelectrostatic polarization of needle shaped metal filaments in the electric\nfield induced by surface imperfections: contaminations, oxide states, etc. A\nproposed theory provides closed form expressions for the whisker nucleation and\ngrowth rates, explains the range of whisker parameters and effects of external\nbiasing. It predicts a well controlled whisker growth on any metal surface via\ngenerating surface plasmon polariton excitations."
    },
    {
        "anchor": "Ab Initio calculation of field emission from metal surfaces with\n  atomic--scale defects: In this work we combine density functional theory and quantum transport\ncalculations to study the influence of atomic--scale defects on the work\nfunction and field emission characteristics of metal surfaces. We develop a\ngeneral methodology for the calculation of the field emitted current density\nfrom nano-featured surfaces, which is then used to study specific defects on a\nCu(111) surface. Our results show that the inclusion of a defect can\nsignificantly locally enhance the field emitted current density. However, this\nincrease is attributed solely to the decrease of the work function due to the\ndefect, with the effective field enhancement being minute. Finally, the\nFowler--Nordheim equation is found to be valid when the modified value for the\nwork function is used, with only an approximately constant factor separating\nthe computed currents from those predicted by the Fowler--Nordheim equation.",
        "positive": "Superfluid Spin Transport through Easy-Plane Ferromagnetic Insulators: Superfluid spin transport $-$ dissipationless transport of spin $-$ is\ntheoretically studied in a ferromagnetic insulator with easy-plane anisotropy.\nWe consider an open geometry where spin current is injected into the\nferromagnet from one side by a metallic reservoir with a nonequilibrium spin\naccumulation, and ejected into another metallic reservoir located downstream.\nSpin transport through the device is studied using a combination of\nmagnetoelectric circuit theory, Landau-Lifshitz-Gilbert phenomenology, and\nmicroscopic linear-response theory. We discuss how spin superfluidity can be\nprobed using a magnetically-mediated electron-drag experiment."
    },
    {
        "anchor": "Dynamics of the polarization of a pinned domain wall in a magnetic\n  nanowire: We consider the dynamics of polarization of a single domain wall in a\nmagnetic nanowire, which is strongly pinned by impurities. In this case the\nequation of motion for the polarization parameter does not include any other\ndynamical variables and is nonlinear due to magnetic anisotropy. We calculated\nnumerically the magnetization dynamics for different choices of parameters\nunder short current pulses inducing polarization switching. Our results show\nthat the switching is most effective for very rapid current pulses. Damping\nalso enhances the switching probability.",
        "positive": "Thermoelectric effects of quantum dot arrays embedded in nanowires: The thermoelectric properties of quantum dot arrays (QDAs) embedded in\nnanowires connected to electrodes are studied theoretically in the Coulomb\nblockade regime. A Hurbbard-Anderson model is used to simulate the electronic\ncontribution to thermoelectric proper- ties of a QDA junction system. The\nelectrical conductance, Seebeck coefficient, and electron thermal conductance\nare calculated by both the Keldysh Green function method and the mean-field\napproach. The phonon thermal conductivities are calculated by using the\nequation of phonon radiative transfer method. In the Coulomb blockade regime\nthe electron thermal conductance is much smaller than the phonon thermal\nconductance. Therefore, the optimal figure of merit (ZT) can be enhanced by\nincreasing thermal power and decreasing phonon thermal conductance\nsimultaneously. We found that it is possible to obtain ZT value of InGaAs/GaAs\nQDAs embedded in nanowires larger than one at room temperature."
    },
    {
        "anchor": "Elementary excitations in the hybrid Bose-Fermi system induced by\n  circularly polarized light in a two-dimensional gas of charge carriers with\n  different masses: We developed a theory describing elementary excitations in the Bose-Fermi\nsystem induced by circularly polarized light in a two-dimensional (2D) gas of\ncharge carriers with different masses. In such a hybrid system, the Fermi\nsubsystem is a degenerate Fermi gas, whereas the Bose subsystem is a condensate\nof the light-induced composite bosons consisting of two fermions (electrons or\nholes) with different effective masses. The interaction of the single-particle\nexcitations and the collective excitations (plasmons) in the Fermi subsystem\nwith the Bogoliubov collective modes (bogolons) in the Bose subsystem is\nanalyzed. The renormalization and damping (lifetime) of the excitations are\ncalculated, and the possibility of their experimental observation is discussed.\nThe developed theory can be applied to describe 2D condensed-matter structures\ncontaining charge carriers with different effective masses, including\ntransition metal dichalcogenide monolayers and semiconductor quantum wells.",
        "positive": "Semiconductor quantum well irradiated by a two-mode electromagnetic\n  field as a terahertz emitter: We study theoretically the nonlinear optical properties of a semiconductor\nquantum well (QW) irradiated by a two-mode electromagnetic wave consisting of a\nstrong resonant dressing field and a weak off-resonant driving field. In the\nconsidered strongly coupled electron-field system, the dressing field opens\ndynamic Stark gaps in the electron energy spectrum of the QW, whereas the\ndriving field induces electron oscillations in the QW plane. Since the gapped\nelectron spectrum restricts the amplitude of the oscillations, the emission of\na frequency comb from the QW appears. Therefore, the doubly-driven QW operates\nas a nonlinear optical element which can be used, particularly, for optically\ncontrolled generation of terahertz radiation."
    },
    {
        "anchor": "Implementation of three-qubit Toffoli gate in a single step: Single-step implementations of multi-qubit gates are generally believed to\nprovide a simpler design, a faster operation, and a lower decoherence. For\ncoupled three qubits interacting with a photon field, a realizable scheme for a\nsingle-step Toffoli gate is investigated. We find that the three qubit system\ncan be described by four effective modified Jaynes-Cummings models in the\nstates of two control qubits. Within the rotating wave approximation, the\nmodified Jaynes-Cummings models are shown to be reduced to the conventional\nJaynes-Cummings models with renormalized couplings between qubits and photon\nfields. A single-step Toffoli gate is shown to be realizable with tuning the\nfour characteristic oscillation periods that satisfy a commensurate condition.\nPossible values of system parameters are estimated for single-step Toffli gate.\nFrom numerical calculation, further, our single-step Toffoli gate operation\nerrors are discussed due to imperfections in system parameters, which shows\nthat a Toffoli gate with high fidelity can be obtained by adjusting pairs of\nthe photon-qubit and the qubit-qubit coupling strengthes. In addition, a\ndecoherence effect on the Toffoli gate operation is discussed due to a thermal\nreservoir.",
        "positive": "Electrical spin driving by $g$-matrix modulation in spin-orbit qubits: In a semiconductor spin qubit with sizable spin-orbit coupling, coherent spin\nrotations can be driven by a resonant gate-voltage modulation. Recently, we\nhave exploited this opportunity in the experimental demonstration of a hole\nspin qubit in a silicon device. Here we investigate the underlying physical\nmechanisms by measuring the full angular dependence of the Rabi frequency as\nwell as the gate-voltage dependence and anisotropy of the hole $g$-factors. We\nshow that a $g$-matrix formalism can simultaneously capture and discriminate\nthe contributions of two mechanisms so far independently discussed in the\nliterature: one associated with the modulation of the $g$ factors, and\nmeasurable by Zeeman energy spectroscopy, the other not. Our approach has a\ngeneral validity and can be applied to the analysis of other types of\nspin-orbit qubits."
    },
    {
        "anchor": "Tunneling transport through multi-electrons states in coupled quantum\n  dots with Coulomb correlations: We investigated the peculiarities of non-equilibrium charge configurations in\nthe system of two strongly coupled quantum dots (QDs) weakly connected to the\nreservoirs in the presence of Coulomb correlations. We revealed that total\nelectron occupation demonstrates in some cases significant decreasing with\nincreasing of applied bias - contrary to the situation when Coulomb\ncorrelations are absent and found well pronounced ranges of system parameters\nwhere negative tunneling conductivity appears due to the Coulomb correlations.",
        "positive": "Impact of local stacking on the graphene-impurity interaction: theory\n  and experiments: We investigate the graphene-impurity interaction problem by combining\nexperimental - scanning tunneling microscopy (STM) and spectroscopy (STS) - and\ntheoretical - Anderson impurity model and density functional theory (DFT)\ncalculations - techniques. We use graphene on the SiC(000-1)(2x2)_C\nreconstruction as a model system. The SiC substrate reconstruction is based on\nsilicon adatoms. Graphene mainly interacts with the dangling bonds of these\nadatoms which act as impurities. Graphene grown on SiC(000-1)(2x2)_C shows\ndomains with various orientations relative to the substrate so that very\ndifferent local graphene/Si adatom stacking configurations can be probed on a\ngiven grain. The position and width of the adatom (impurity) state can be\nanalyzed by STM/STS and related to its local environment owing to the high bias\nelectronic transparency of graphene. The experimental results are compared to\nAnderson's model predictions and complemented by DFT calculations for some\nspecific local environments. We conclude that the adatom resonance shows a\nsmaller width and a larger shift toward the Dirac point for an adatom at the\ncenter of a graphene hexagon than for an adatom just on top of a C graphene\natom."
    },
    {
        "anchor": "Quantitative study of electronic whispering gallery modes in\n  electrostatic-potential induced circular graphene junctions: Electronic Whispering Gallery Modes (EWGMs) have been recently observed in\nseveral circular graphene junctions, pn and pp0, created in scanning tunnelling\nmicroscope experiments. By computing the local density of states within the\nDirac-Weyl formalism for massless fermions we demonstrate that the EWGMs may\nreally be emerged in any type of the electrostatic potential induced circular\ngraphene junctions, including uni-junctions (e.g. np- or pp0-junctions) as well\nas bipolar-junctions (e.g. pnp-heterojunctions). Surprisingly, quantitative\nanalyses show that for all the EWGMs identified (regardless of junction types)\nthe quality (Q) factors seem to be smaller than 100, very small compared to\nthose in ordinary optical whispering gallery modes microresonators, while the\ncorresponding mode radii may tunably be in nanometer-scale. Our theoretical\nresults are in good agreement with existent experimental data, putting a\nquestion to the application potential of the EWGMs identified.",
        "positive": "Circularly polarized electroluminescence from silicon nanostructures\n  heavily doped with boron: The circularly polarized electroluminescence (CPEL) from silicon\nnanostructures which are the p-type ultra-narrow silicon quantum well (Si-QW)\nconfined by {\\delta}-barriers heavily doped with boron, 5 10^21 cm^-3, is under\nstudy as a function of temperature and excitation levels. The CPEL dependences\non the forward current and temperature show the circularly polarized light\nemission which appears to be caused by the exciton recombination through the\nnegative-U dipole boron centers at the Si-QW {\\delta}-barriers interface."
    },
    {
        "anchor": "Shot noise of spin current in ferromagnet-normal-metal systems: We propose a three-terminal spin-valve setup, to determine experimentally the\nspin-dependent shot noise, which carries information on the spin-relaxation\nprocesses. Based on a spin-dependent Boltzmann-Langevin approach, we show that\nthe spin Fano factor, defined as the spin shot noise to the mean charge\ncurrent, strongly depends on the spin-flip scattering rate in the normal wire.\nWhile in the parallel configuration the spin Fano factor always decreases below\nits unpolarized value with increasing spin injection, for the antiparallel case\nit varies nonmonotonically. We also show that in contrast to the charge current\nFano factor, which varies appreciable only in the antiparallel case, the spin\nFano factor allows for a more sensitive determination of the spin-flip\nscattering rate.",
        "positive": "Electronic transport in two dimensional graphene: We provide a broad review of fundamental electronic properties of\ntwo-dimensional graphene with the emphasis on density and temperature dependent\ncarrier transport in doped or gated graphene structures. A salient feature of\nour review is a critical comparison between carrier transport in graphene and\nin two-dimensional semiconductor systems (e.g. heterostructures, quantum wells,\ninversion layers) so that the unique features of graphene electronic properties\narising from its gap- less, massless, chiral Dirac spectrum are highlighted.\nExperiment and theory as well as quantum and semi-classical transport are\ndiscussed in a synergistic manner in order to provide a unified and\ncomprehensive perspective. Although the emphasis of the review is on those\naspects of graphene transport where reasonable consensus exists in the\nliterature, open questions are discussed as well. Various physical mechanisms\ncontrolling transport are described in depth including long- range charged\nimpurity scattering, screening, short-range defect scattering, phonon\nscattering, many-body effects, Klein tunneling, minimum conductivity at the\nDirac point, electron-hole puddle formation, p-n junctions, localization,\npercolation, quantum-classical crossover, midgap states, quantum Hall effects,\nand other phenomena."
    },
    {
        "anchor": "Space charge limited conduction with exponential trap distribution in\n  reduced graphene oxide sheets: We elucidate on the low mobility and charge traps of the chemically reduced\ngraphene oxide (RGO) sheets by measuring and analyzing temperature dependent\ncurrent-voltage characteristics. The RGO sheets were assembled between source\nand drain electrodes via dielectrophoresis. At low bias voltage the conduction\nis Ohmic while at high bias voltage and low temperatures the conduction becomes\nspace charge limited with an exponential distribution of traps. We estimate an\naverage trap density of 1.75x10^16 cm^-3. Quantitative information about charge\ntraps will help develop optimization strategies of passivating defects in order\nto fabricate high quality solution processed graphene devices.",
        "positive": "Theoretical insights on the importance of anchoring vs molecular\n  geometry in magnetic molecules acting as junctions: The anchoring of the molecule to an electrode is known to be a key factor in\nsingle-molecule spintronics experiments. Likewise, a relaxation down to the\nmost stable geometry is a critical step in theoretical simulations of transport\nthrough single-molecule junctions. Herein we present a set of calculations\ndesigned to analyze and compare the effect of different anchoring points and\nthe effect of perturbations in the molecular geometry and interelectrode\ndistance. As model system we chose the [V($\\alpha$-C$_3$S$_5$)$_3$]$^{2-}$\ncomplex connecting two Au(111) electrodes in a slightly compressed geometry. In\nour calculations, the attachment happens through an S-Au bond, a common\nanchoring strategy in molecular spintronics experiments. Our results confirm\nthat small alterations in the molecular geometry have important effects in the\nconductance. We were able to compare these effects with the ones arising from\nchanging the anchoring position with a constant molecular geometry.\nUnexpectedly, we demonstrate that the anchoring position has only a lesser\nrelevance in the spintronic behavior of the device, as long as all other\nparameters are kept frozen. As a consequence, we predict that for\nexperimentalists aiming for reproducibility, the molecular design of rigid\nlinkers is more relevant than the design of univocal anchoring positions."
    },
    {
        "anchor": "Nuclear-induced time evolution of entanglement of two-electron spins in\n  anisotropically coupled quantum dot: We study the time evolution of entanglement of two spins in anisotropically\ncoupled quantum dot interacting with the unpolarized nuclear spins environment.\nWe assume that the exchange coupling strength in the z-direction $J_z$ is\ndifferent from the lateral one $J_l$. We observe that the entanglement decays\nas a result of the coupling to the nuclear environment and reaches a saturation\nvalue, which depends on the value of the exchange interaction difference $J=\\|\nJ_l-J_z\\|$ between the two spins and the strength of the applied external\nmagnetic field. We find that the entanglement exhibits a critical behavior\ncontrolled by the competition between the exchange interaction $J$ and the\nexternal magnetic field. The entanglement shows a quasi-symmetric behavior\nabove and below a critical value of the exchange interaction. It becomes more\nsymmetric as the external magnetic field increases. The entanglement reaches a\nlarge saturation value, close to unity, when the exchange interaction is far\nabove or below its critical value and a small one as it closely approaches the\ncritical value. Furthermore, we find that the decay rate profile of\nentanglement is linear when the exchange interaction is much higher or lower\nthan the critical value but converts to a power law and finally to a Gaussian\nas the critical value is approached from both directions. The dynamics of\nentanglement is found to be independent of the exchange interaction for\nisotropically coupled quantum dot.",
        "positive": "Stimulated and spontaneous optical generation of electron spin coherence\n  in charged GaAs quantum dots: We report on the coherent optical excitation of electron spin polarization in\nthe ground state of charged GaAs quantum dots via an intermediate charged\nexciton (trion) state. Coherent optical fields are used for the creation and\ndetection of the Raman spin coherence between the spin ground states of the\ncharged quantum dot. The measured spin decoherence time, which is likely\nlimited by the nature of the spin ensemble, approaches 10 ns at zero field. We\nalso show that the Raman spin coherence in the quantum beats is caused not only\nby the usual stimulated Raman interaction but also by simultaneous spontaneous\nradiative decay of either excited trion state to a coherent combination of the\ntwo spin states."
    },
    {
        "anchor": "Cavity magnomechanics with surface acoustic waves: Magnons, namely spin waves, are collective spin excitations in ferromagnets,\nand their control through coupling with other excitations is a key technology\nfor future hybrid spintronic devices. Although strong coupling has been\ndemonstrated with microwave photonic structures, an alternative approach\npermitting high density integration and minimized electromagnetic crosstalk is\nrequired. Here we report a planar cavity magnomechanical system, where the\ncavity of surface acoustic waves enhances the spatial and spectral power\ndensity to thus implement magnon-phonon coupling at room temperature.\nExcitation of spin-wave resonance involves significant acoustic power\nabsorption, whereas the collective spin motion reversely exerts a back-action\nforce on the cavity dynamics. The cavity frequency and quality-factor are\nsignificantly modified by the back-action effect, and the resultant\ncooperativity exceeds unity, suggesting coherent interaction between magnons\nand phonons. The demonstration of a chip-scale magnomechanical system paves the\nway to the development of novel spin-acoustic technologies for classical and\nquantum applications.",
        "positive": "Hyperfine interaction dominated dynamics of nuclear spins in\n  self-assembled quantum dots: We measure the dynamics of nuclear spins in a self-assembled quantum dot at a\nmagnetic field of 5 Tesla and identify two distinct mechanisms responsible for\nthe decay of the Overhauser field. We attribute a temperature-independent decay\nwhich lasts ~100 seconds to intra-dot diffusion induced by hyperfine-mediated\nindirect nuclear spin interaction. In addition, we observe a gate-voltage and\ntemperature dependent decay stemming from co-tunneling mediated nuclear spin\nflip processes. By adjusting the gate-voltage and lowering the electron\ntemperature to ~200 milliKelvin, we prolong the corresponding decay time to ~30\nhours. Our measurements indicate possibilities for exploring quantum dynamics\nof the central spin model using a single self-assembled quantum dot."
    },
    {
        "anchor": "Edge-Insensitive Magnetism and Half Metallicity in Graphene Nanoribbons: Realizing magnetism in graphene/carbon nanostructures is a decade-long\nchallenge. The magnetic edge state and half metallicity in zigzag graphene\nnanoribbons are particularly promising [Y.-W. Son, et al., Nature 444, 347\n(2006)]. However, its experimental realization has been hindered by the\nstringent requirement of the mono-hydrogenated zigzag edge. Using\nfirst-principle calculations, we predict that free-carrier doping can overcome\nthis challenge and realize ferromagnetism and half-metallicity in narrow\ngraphene nanoribbons of general types of edge structures. This magnetism exists\nwithin the density range of gate-doping experiments (~1013 cm-2) and has large\nspin polarization energy up to 17 meV per carrier, which induces a Zeeman\nsplitting equivalent to an external magnetic field of a few hundred Tesla.\nFinally, we trace the formation mechanics of this edge-insensitive magnetism to\nthe quantum confinement of the electronic state near the band edge and reveal\nthe scaling law of magnetism versus the ribbon width. Our findings suggest that\ncombining doping with quantum confinement could be a general tool to realize\ntransition-metal-free magnetism in light-element nanostructures.",
        "positive": "Photoinduced pseudospin effects in silicene beyond the off resonant\n  condition: We study the photoinduced manipulation of charge carriers in monolayer\nsilicene subject to intense electromagnetic terahertz radiation. Considering\nthe Dirac cone approximation and going beyond the off resonant condition for\nlarge frequencies of the radiation field, where only virtual photon processes\nare allowed, we present the exact zero-momentum pseudospin polarization and\nnumerical results for the quasienergy band structure and time-averaged density\nof states. We find that resonant processes, due to real photon emission and\nabsorbtion processes, induce a band inversion that qualitatively modifies the\nquasienergy spectrum. These band structure changes manifest themselves as an\ninversion of the averaged pseudospin polarization. Through the analysis of the\ntime-averaged density of states we find that effective photoinduced gap\nmanipulation can only be achieved in the intermediate and strong\nmatter-radiation coupling regime where the off resonant approximation breaks\ndown."
    },
    {
        "anchor": "Broadened Yu-Shiba-Rusinov states in dirty superconducting films and\n  heterostructures: The interplay of a potential and magnetic disorder in superconductors remains\nan active field of research for decades. Within the framework of the Usadel\nequation, we study the local density of states near a solitary classical\nmagnetic impurity in a dirty superconducting film. We find that a potential\ndisorder results in broadening of the delta-function in the local density of\nstates at the Yu-Shiba-Rusinov (YSR) energy. This broadening is proportional to\nthe square root of a normal-state spreading resistance of the film. We\ndemonstrate that mesoscopic fluctuations caused by a potential disorder affect\ncrucially a profile of the local density of states in the vicinity of the YSR\nenergy. In addition, we demonstrate that a scanning-tunneling-microscopy tip\ncan mask an YSR feature in the local density of states. Also, we study the\nlocal density of states near a chain of magnetic impurities situated in the\nnormal region of a dirty superconductor/normal-metal junction. We find a\nresonance in the local density of states near the YSR energy. The energy scale\nof the resonant peak is controlled by the square root of the film resistance\nper square in the normal state.",
        "positive": "Evolution of Majorona zero-energy edge states in a $T^2 = -1$ symmetry\n  protected 1D topological superconductor with dominant spin-orbit coupling: We consider a 1D topological superconductor (TSC) constructed by coupling a\npair of Kitaev's Majorana chains with opposite spin configurations. Such a 1D\nlattice model is known to be protected by a $T^2 = -1$ time-reversal symmetry.\nFurthermore, we consider a modeled Rashba spin-orbit coupling on such a system\nof $T^2=-1$ time-reversal symmetric TSC. The Rashba spin-orbit coupling\ntogether with the chemical potential engineered the phase transitions of the\nedge states in the system and consequently the number of Majorona's zero-energy\nedge modes (MZM's) emerging at the edge of the coupled chains. Correspondingly,\nthe topological nature of the system is described by a phase diagram consisting\nof three different phases. The three phases are characterized by a topological\nwinding number, $\\mathcal{W}=1$, $2$ (with one and two MZM's: topological\nphases) and $\\mathcal{W}=0$ (devoid of any MZM: trivial insulating phase)."
    },
    {
        "anchor": "Sequential tunneling and shot noise in\n  ferromagnet/normal-metal/ferromagnet double tunnel junctions: The tunneling through a ferromagnet/normal metal/ferromagnet double junction\nin the Coulomb blockade regime is studied, assuming that the spin relaxation\ntime of electron in the central metallic island is sufficiently large. Using\nthe master equation, the current, the tunnel magnetoresistance (TMR), and the\ncurrent noise spectrum have been calculated for devices of different\nparameters. It was shown that the interplay between spin and charge\ncorrelations strongly depends on the asymmetry of measured device. The charge\ncorrelation makes both the chemical potential shift, which describes the spin\naccumulation in the central island, and the TMR oscillated with the same period\nas the Coulomb staircase in current-voltage characteristics. This effect is\nsmeared by the temperature. The spin correlation may cause an enhancement of\nnoise at finite frequencies, while the zero frequency noise is still always\nsub-poissonian. The gate voltage causes an oscillation of not only conductance,\nbut also TMR and noise.",
        "positive": "Nonequilibrium plasmons with gain in graphene: Graphene supports strongly confined transverse-magnetic sheet plasmons whose\nspectral characteristics depend on the energetic distribution of Dirac\nparticles. The question arises whether plasmons can become amplified when\ngraphene is pumped into a state of inversion. In establishing a theory for the\ndynamic non-equilibrium polarizability, we are able to determine the exact\ncomplex-frequency plasmon dispersion of photo-inverted graphene and study the\nimpact of doping, collision loss, and temperature on the plasmon gain. We\ncalculate the spontaneous emission spectra and carrier recombination rates\nself-consistently and compare the results with approximations based on Fermi's\ngolden rule. Our results show that amplification of plasmons is possible under\nrealistic conditions but inevitably competes with ultrafast spontaneous\nemission, which for intrinsic graphene, is a factor 5 faster than previously\nestimated. This work casts new light on the nature of non-equilibrium plasmons\nand may aid the experimental realization of active plasmonic devices based on\ngraphene."
    },
    {
        "anchor": "Theory of a Magnetically-Controlled Quantum-Dot Spin Transistor: We examine transport through a quantum dot coupled to three ferromagnetic\nleads in the regime of weak tunnel coupling. A finite source-drain voltage\ngenerates a nonequilibrium spin on the otherwise non-magnetic quantum dot. This\nspin accumulation leads to magnetoresistance. A ferromagnetic but current-free\nbase electrode influences the quantum-dot spin via incoherent spin-flip\nprocesses and coherent spin precession. As the dot spin determines the\nconductance of the device, this allows for a purely magnetic transistor-like\noperation. We analyze the effect of both types of processes on the electric\ncurrent in different geometries.",
        "positive": "Light-induced emergent phenomena in 2D materials and topological\n  materials: Light-matter interaction in 2D and topological materials provides a\nfascinating control knob for inducing emergent, non-equilibrium properties and\nachieving new functionalities in the ultrafast time scale (from fs to ps). Over\nthe past decade, intriguing light-induced phenomena, e.g., Bloch-Floquet states\nand photo-induced phase transitions, have been reported experimentally, but\nmany still await experimental realization. In this Review, we discuss recent\nprogress on the light-induced phenomena, in which the light field could act as\na time-periodic field to drive Floquet states, induce structural and\ntopological phase transitions in quantum materials, couple with spin and\nvarious pseudospins, and induce nonlinear optical responses that are affected\nby the geometric phase. Perspectives on the opportunities of proposed\nlight-induced phenomena as well as open experimental challenges are also\ndiscussed."
    },
    {
        "anchor": "Excitation spectrum of Andreev billiards with a mixed phase space: We present a semiclassical theory for the excitation spectrum of a ballistic\nquantum dot weakly coupled to a superconductor, for the generic situation that\nthe classical motion gives rise to a phase space containing islands of\nregularity in a chaotic sea. The density of low-energy excitations is\ndetermined by quantum energy scales that are related in a simple way to the\nmorphology of the mixed phase space. An exact quantum mechanical computation\nfor the annular billiard shows good agreement with the semiclassical\npredictions, in particular for the reduction of the excitation gap when the\ncoupling to the regular regions is maximal.",
        "positive": "Mapping the magnonic landscape in patterned magnetic structures: We report the development of a hybrid numerical / analytical model capable of\nmapping the spatially-varying distributions of the local ferromagnetic\nresonance (FMR) frequency and dynamic magnetic susceptibility in a wide class\nof patterned and compositionally modulated magnetic structures. Starting from\nthe numerically simulated static micromagnetic state, the magnetization is\ndeliberately deflected orthogonally to its equilibrium orientation, and the\nmagnetic fields generated in response to this deflection are evaluated using\nmicromagnetic software. This allows us to calculate the elements of the\neffective demagnetizing tensor, which are then used within a linear analytical\nformalism to map the local FMR frequency and dynamic magnetic susceptibility.\nTo illustrate the typical results that one can obtain using this model, we\nanalyze three micromagnetic systems boasting non-uniformity in either one or\ntwo dimensions, and successfully explain the spin-wave emission observed in\neach case, demonstrating the ubiquitous nature of the Schl\\\"omann excitation\nmechanism underpinning the observations. Finally, the developed model of local\nFMR frequency could be used to explain how spin waves could be confined and\nsteered using magnetic non-uniformities of various origins, rendering it a\npowerful tool for the mapping of the graded magnonic index in magnonics."
    },
    {
        "anchor": "Topological flat bands in strained graphene: substrate engineering and\n  optical control: The discovery of correlated phases in twisted moir\\'e superlattices\naccelerated the search for low-dimensional materials with exotic properties. A\npromising approach uses engineered substrates to strain the material. However,\ndesigning substrates for tailored properties is hindered by the incomplete\nunderstanding of the relationship between substrate's shapes and electronic\nproperties of the deposited materials. By analyzing effective models of\ngraphene under periodic deformations with generic crystalline profiles, we\nidentify strong $C_{2z}$ symmetry breaking as the critical substrate geometric\nfeature for emerging energy gaps and quasi-flat bands. We find continuous\nstrain profiles producing connected pseudo-magnetic field landscapes are\nimportant for band topology. We show that the resultant electronic and\ntopological properties from a substrate can be controlled with circularly\npolarized light, which also offers unique signatures for identifying the band\ntopology imprinted by strain. Our results can guide experiments on strain\nengineering for exploring interesting transport and topological phenomena.",
        "positive": "Manifestly non-Gaussian fluctuations in superconductor-normal metal\n  tunnel nanostructures: We propose a mesoscopic setup which exhibits strong and manifestly\nnon-Gaussian fluctuations of energy and temperature when suitably driven out of\nequilibrium. The setup consists of a normal metal island (N) coupled by tunnel\njunctions (I) to two superconducting leads (S), forming a SINIS structure, and\nis biased near the threshold voltage for quasiparticle tunneling,\n$eV\\approx2\\Delta$. The fluctuations can be measured by monitoring the\ntime-dependent electric current through the system, which makes the setup\nsuitable for the realization of feedback schemes which allow to stabilize the\ntemperature to the desired value."
    },
    {
        "anchor": "Instabilities in the optical response of a semiconductor quantum dot -\n  metal nanoparticle heterodimer: self - oscillations and chaos: We theoretically investigate the nonlinear optical response of a heterodimer\ncomprising a semiconductor quantum dot strongly coupled to a metal\nnanoparticle. The quantum dot is considered as a three-level ladder system with\nground, one-exciton, and bi-exction states. As compared to the case of a\ntwo-level quantum dot model, adding the third (bi-exciton) state produces\nfascinating effects in the optical response of the hybrid system. Specifically,\nwe demonstrate that the system may exhibit picosecond and sub-picosecond\nself-oscillations and quasi-chaotic behaviour under {\\it single}-frequency\ncontinuous wave excitation. An isolated semiconductor quantum dot does not show\nsuch features. The effects originate from competing one-exciton and bi-exciton\ntransitions in the semiconductor quantum dot, triggered by the self-action of\nthe quantum dot via the metal nanoparticle. The key parameter that governs the\nphenomena mentioned is the ratio of the self-action strength and the bi-exciton\nshift. The self-oscillation regime can be achieved in practice, in particular,\nin a heterodimer comprised of a closely spaced ZnS/ZnSe core-shell quantum dot\nand a spherical silver nanoparticle. The results may have applications in\nnanodevices for generating trains of ultrashort optical pulses.",
        "positive": "Going beyond k.p theory: a general method for obtaining effective\n  Hamiltonians in both high and low symmetry situations: We provide a method for the generation of effective continuum Hamiltonians\nthat goes beyond the well known k.p method in being equally effective in both\nhigh, and low (or no) symmetry situations. Our approach is based on a\nsurprising exact map of the two-centre tight-binding method onto a compact\ncontinuum Hamiltonian, with a precise condition given for the hermiticity of\nthe latter object. We apply this method to a broad range of low dimensional\nsystems of both high and low symmetry: graphene, graphdiyne, {\\gamma}-graphyne,\n6,6,12-graphyne, twist bilayer graphene, and partial dislocation networks in\nBernal stacked bilayer graphene. For the single layer systems the method yields\nHamiltonians for the ideal lattices, as well as a systematic theory for\ncorrections due to deformation. In the case of bilayer graphene we provide a\ncompact expression for an effective field capable of describing any stacking\ndeformation of the bilayer; twist bilayer graphene, as well as the partial\ndislocation network in AB stacked graphene, emerge as special cases of this\nfield. For the latter system we find (i) charge pooling on the mosaic of AB and\nAC segments near the Dirac point and (ii) localized current carrying states on\nthe partials with the current density characterized by both intralayer and\ninterlayer components."
    },
    {
        "anchor": "Current noise enhancement: channel mixing and possible nonequilibrium\n  phonon backaction in atomic-scale Au junctions: We report measurements of the bias dependence of the Fano factor in ensembles\nof atomic-scale Au junctions at 77 K. Previous measurements of shot noise at\nroom temperature and low biases have found good agreement of the Fano factor\nwith the expectations of the Landauer- B\\\"uttiker formalism, while enhanced\nFano factors have been observed at biases of hundreds of mV [R. Chen et al.,\nSci. Rep. 4, 4221 (2014)]. We find even stronger enhancement of shot noise at\n77 K with an \"excess\" Fano factor up to ten times the low bias value. We\ndiscuss the observed ensemble Fano factor bias dependence in terms of candidate\nmodels. The results are most consistent with either a bias-dependent channel\nmixing picture or a model incorporating noise enhancement due to\ncurrent-driven, nonequilibrium phonon populations, though a complete\ntheoretical treatment of the latter in the ensemble average limit is needed.",
        "positive": "Exciton-Polariton Topological Insulator with an Array of Magnetic Dots: Recently there have been several proposals on exciton-polariton topological\ninsulators, most requiring strong external magnetic fields induced by bulky\nsuperconducting coils. We propose an alternate design for a polariton\ntopological insulator, where excitons are in a proximity of an additional layer\nof a ferromagnetic material with a predefined magnetic moment located between\nthe pillars of the cavity. Our design supports a variety of topological phases\nand transitions between Chern numbers $\\pm 2$ and $\\pm 1$ by varying either the\nmagnetic moment of the ferromagnetic material or the spin-orbit coupling\nbetween different spin projections, thus enabling compact polariton devices\nharnessing switchable topological edge modes."
    },
    {
        "anchor": "Configuration interaction in delta-doped heterostructures: We analyze the tunnel coupling between an impurity state located in a\n$\\delta$-layer and the 2D delocalized states in the quantum well (QW) located\nat a few nanometers from the $\\delta$ -- layer. The problem is formulated in\nterms of Anderson-Fano model as configuration interaction between the carrier\nbound state at the impurity and the continuum of delocalized states in the QW.\nAn effect of this interaction on the interband optical transitions in the QW is\nanalyzed. The results are discussed regarding the series of experiments on the\nGaAs structures with a $\\delta$-Mn layer.",
        "positive": "Fabry-Perot interferometry in Weyl semi-metals: We show that the electrical transport across a minimal model for a\ntime-reversal symmetry(TRS) breaking Weyl semi-metal (WSM) involving two Weyl\nnodes can be interpreted as an interferometer in momentum space. The\ninterference phase depends on the distance between the Weyl nodes ($\\vec{\\delta\nk}$) and is {\\it anisotropic}. It is further shown that a minimal inversion\nsymmetry broken model for a WSM with four Weyl nodes effectively mimics a\nsituation corresponding to having two copies of the interferometer due to the\npresence of an orbital pseudo-spin domain wall in momentum space. We point out\nthat the value of the $\\delta k$ and consequently the interference phase can be\ntuned by driving the WSMs resulting in oscillations in the two terminal\nconductance measured in the direction of splitting of the Weyl nodes."
    },
    {
        "anchor": "Microwave Experiments Simulating Quantum Search and Directed Transport\n  in Artificial Graphene: A series of quantum search algorithms have been proposed recently providing\nan algebraic speedup compared to classical search algorithms from $N$ to\n$\\sqrt{N}$, where $N$ is the number of items in the search space. In\nparticular, devising searches on regular lattices has become popular in\nextending Grover's original algorithm to spatial searching. Working in a\ntight-binding setup, it could be demonstrated, theoretically, that a search is\npossible in the physically relevant dimensions 2 and 3 if the lattice spectrum\npossesses Dirac points. We present here a proof of principle experiment\nimplementing wave search algorithms and directed wave transport in a graphene\nlattice arrangement. The idea is based on bringing localized search states into\nresonance with an extended lattice state in an energy region of low spectral\ndensity---namely, at or near the Dirac point. The experiment is implemented\nusing classical waves in a microwave setup containing weakly coupled dielectric\nresonators placed in a honeycomb arrangement, i.e., artificial graphene.\nFurthermore, we investigate the scaling behavior experimentally using linear\nchains.",
        "positive": "Polaron contributions to the biexciton binding energies in\n  self-assembled quantum dots: The contribution to the biexciton binding energy in quantum dots resulting\nfrom the interaction with longitudinal optical phonons is estimated by\nperforming the configuration--interaction calculation of the few-particle\nstates in a simple model of the confining potential and including the phonon\ncorrections by means of a perturbation theory. It is found that the polaron\ncontribution tends to compensate the Coulomb-related biexciton shift (binding\nenergy) and reduces its value by several to even 30%, depending on the material\nparameters of the system."
    },
    {
        "anchor": "Magnon-Mediated Dzyaloshinskii-Moriya Torque in Homogeneous Ferromagnets: In thin magnetic layers with structural inversion asymmetry and spin-orbit\ncoupling, a Dzyaloshinskii-Moriya interaction arises at the interface. When a\nspin wave current ${\\bf j}_m$ flows in a system with a homogeneous\nmagnetization {\\bf m}, this interaction produces an effective field-like torque\non the form ${\\bf T}_{\\rm FL}\\propto{\\bf m}\\times({\\bf z}\\times{\\bf j}_m)$ as\nwell as a damping-like torque, ${\\bf T}_{\\rm DL}\\propto{\\bf m}\\times[({\\bf\nz}\\times{\\bf j}_m)\\times{\\bf m}]$ in the presence of spin-wave relaxation\n(${\\bf z}$ is normal to the interface). These torques mediated by the magnon\nflow can reorient the time-averaged magnetization direction and display a\nnumber of similarities with the torques arising from the electron flow in a\nmagnetic two dimensional electron gas with Rashba spin-orbit coupling. This\nmagnon-mediated spin-orbit torque can be efficient in the case of magnons\ndriven by a thermal gradient.",
        "positive": "$\u03c0-0$ Transition in Superconductor-Ferromagnetic-Superconductor\n  Junctions: Superconductor-Ferromagnetic-Superconductor (SFS) Josephson junctions are\nknown to exhibit a transition between $\\pi$ and 0 states. In this note we find\nthe $\\pi-0$ phase diagram of an SFS junction depending on the transparency of\nan intermediate insulating layer (I). We show that in general, the Josephson\ncritical current is nonzero at the $\\pi-0$ transition temperature.\nContributions to the current from the two spin channels nearly compensate each\nother and the first harmonic of the Josephson current as a function of phase\ndifference is suppressed. However, higher harmonics give a nonzero contribution\nto the supercurrent."
    },
    {
        "anchor": "Wiedemann-Franz law in graphene: We analyze a well-known experimental work [J. Crossno et al., Science 351,\n1058 (2016)] which reported on the failure of the Wiedemann-Franz law in\ngraphene at $T\\sim 10$-$100\\,\\mathrm{K}$, attributing this failure to the\nnon-Fermi liquid nature of the Dirac fluid associated with undoped intrinsic\ngraphene. In spite of serious theoretical efforts, the reported observations\nremain unexplained. Our detailed quantitative analysis based on Fermi liquid\nconsiderations, which apply to extrinsic doped graphene, establishes that one\npossible explanation for the reported observations is the opening of a gap at\nthe Dirac point, induced perhaps by the boron nitride substrate. We suggest\nthat more experiments are necessary to resolve the issue, and we believe that\nthe experiment may not actually have anything to do with Dirac fluid\nhydrodynamics, but relates to finite-temperature low-density bipolar diffusive\ntransport by electrons and holes in the presence of short- and long-range\ndisorder, and phonons.",
        "positive": "Coulomb oscillations of the Fano-Kondo effect and zero bias anomalies in\n  the double dot meso-transistor: We investigate theoretically the transport properties of the side-coupled\ndouble quantum dots in connection with the experimental study of Sasaki {\\it et\nal.} Phys.Rev.Lett.{\\bf 103}, 266806 (2009). The novelty of the set-up consists\nin connecting the Kondo dot directly to the leads, while the side dot provides\nan interference path which affects the Kondo correlations. We analyze the\noscillations of the source-drain current due to the periodical Coulomb blockade\nof the many-level side-dot at the variation of the gate potential applied on\nit. The Fano profile of these oscillations may be controlled by the\ntemperature, gate potential and interdot coupling. The non-equilibrium\nconductance of the double dot system exhibits zero bias anomaly which, besides\nthe usual enhancement, may show also a suppression (a dip-like aspect) which\noccurs around the Fano {\\it zero}. In the same region, the weak temperature\ndependence of the conductance indicates the suppression of the Kondo effect.\nScaling properties of the non-equilibrium conductance in the Fano-Kondo regime\nare discussed. Since the SIAM Kondo temperature is no longer the proper scaling\nparameter, we look for an alternative specific to the double-dot. The extended\nAnderson model, Keldysh formalism and equation of motion technique are used."
    },
    {
        "anchor": "Charge transfer through molecular junctions within Redfield theory:\n  subtleties and pitfalls: Charge transfer through nanoscale junctions connecting metallic leads with\nquantum dots or single molecules is often described within an open system\nformulation in terms of Redfield theory. Under non-equilibrium conditions, the\nusually invoked rotating wave approximation is not justified which may lead to\nunphysical steady state solutions with e.g. negative populations. In this work\nwe explore subtleties and constraints of the approach and thus clarify its\napplicability in numerical calculations. General findings are illustrated for\nan analytically solvable case of a molecule with two electronic states.",
        "positive": "Quantum advantage in a molecular spintronic engine that harvests thermal\n  fluctuation energy: Recent theory and experiments have showcased how to harness quantum mechanics\nto assemble heat/information engines with efficiencies that surpass the\nclassical Carnot limit. So far, this has required atomic engines that are\ndriven by cumbersome external electromagnetic sources. Here, using molecular\nspintronics, we propose an implementation that is both electronic and\nautonomous. Our spintronic quantum engine heuristically deploys several known\nquantum assets by having a chain of spin qubits formed by the paramagnetic Co\ncenters of phthalocyanine (Pc) molecules electronically interact with\nelectron-spin selecting Fe/C60 interfaces. Density functional calculations\nreveal that transport fluctuations across the interface can stabilize spin\ncoherence on the Co paramagnetic centers, which host spin flip processes.\nAcross vertical molecular nanodevices, we measure enduring dc current\ngeneration, output power above room temperature, two quantum thermodynamical\nsignatures of the engine's processes, and a record 89% spin polarization of\ncurrent across the Fe/C60 interface. It is crucially this electron spin\nselection that forces, through demonic feedback and control, charge current to\nflow against the built-in potential barrier. Further research into spintronic\nquantum engines, insight into the quantum information processes within\nspintronic technologies, and retooling the spintronic-based information\ntechnology chain, could help accelerate the transition to clean energy."
    }
]